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Sample records for direct photon-counting scintillation

  1. Direct photon-counting scintillation detector readout using an SSPM

    International Nuclear Information System (INIS)

    Stapels, Christopher J.; Squillante, Michael R.; Lawrence, William G.; Augustine, Frank L.; Christian, James F.

    2007-01-01

    Gamma-ray detector technologies, capable of providing adequate energy information, use photomultiplier tubes (PMTs) or silicon avalanche photodiodes to detect the light pulse from a scintillation crystal. A new approach to detect the light from scintillation materials is to use an array of small photon counting detectors, or a 'detector-on-a-chip' based on a novel 'Solid-state Photomultiplier' (SSPM) concept. A CMOS SSPM coupled to a scintillation crystal uses an array of CMOS Geiger photodiode (GPD) pixels to collect light and produce a signal proportional to the energy of the radiation. Each pixel acts as a binary photon detector, but the summed output is an analog representation of the total photon intensity. We have successfully fabricated arrays of GPD pixels in a CMOS environment, which makes possible the production of miniaturized arrays integrated with the detector electronics in a small silicon chip. This detector technology allows for a substantial cost reduction while preserving the energy resolution needed for radiological measurements. In this work, we compare designs for the SSPM detector. One pixel design achieves maximum detection efficiency (DE) for 632-nm photons approaching 30% with a room temperature dark count rate (DCR) of less than 1 kHz for a 30-μm-diameter pixel. We characterize after pulsing and optical cross talk and discuss their effects on the performance of the SSPM. For 30-μm diameter, passively quenched CMOS GPD pixels, modeling suggests that a pixel spacing of approximately 90 μm optimizes the SSPM performance with respect to DE and cross talk

  2. Measurement of scintillation decay curves by a single photon counting technique

    International Nuclear Information System (INIS)

    Noguchi, Tsutomu

    1978-01-01

    An improved apparatus suitable for the measurement of spectroscopic scintillation decay curves has been developed by combination of a single photon counting technique and a delayed coincidence method. The time resolution of the apparatus is improved up to 1.16 nsec (FWHM), which is obtained from the resolution function of the system for very weak Cherenkov light flashes. Systematic measurement of scintillation decay curves is made for liquid and crystal scintillators including PPO-toluene, PBD-xylene, PPO-POPOP-toluene, anthracene and stilbene. (auth.)

  3. Comparison of image uniformity with photon counting and conventional scintillation single-photon emission computed tomography system: A Monte Carlo simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ho Chul; Lee, Young Jin [Dept. of Radiological Science, Eulji University, Seongnam (Korea, Republic of); Kim, Hee Joung; Kim, Kyuseok; Lee, Min Hee [Yonsei University, Wonju (Korea, Republic of)

    2017-06-15

    To avoid imaging artifacts and interpretation mistakes, an improvement of the uniformity in gamma camera systems is a very important point. We can expect excellent uniformity using cadmium zinc telluride (CZT) photon counting detector (PCD) because of the direct conversion of the gamma rays energy into electrons. In addition, the uniformity performance such as integral uniformity (IU), differential uniformity (DU), scatter fraction (SF), and contrast-to-noise ratio (CNR) varies according to the energy window setting. In this study, we compared a PCD and conventional scintillation detector with respect to the energy windows (5%, 10%, 15%, and 20%) using a {sup 99m}Tc gamma source with a Geant4 Application for Tomography Emission simulation tool. The gamma camera systems used in this work are a CZT PCD and NaI(Tl) conventional scintillation detector with a 1-mm thickness. According to the results, although the IU and DU results were improved with the energy window, the SF and CNR results deteriorated with the energy window. In particular, the uniformity for the PCD was higher than that of the conventional scintillation detector in all cases. In conclusion, our results demonstrated that the uniformity of the CZT PCD was higher than that of the conventional scintillation detector.

  4. Imaging performance comparison between a LaBr3: Ce scintillator based and a CdTe semiconductor based photon counting compact gamma camera.

    Science.gov (United States)

    Russo, P; Mettivier, G; Pani, R; Pellegrini, R; Cinti, M N; Bennati, P

    2009-04-01

    The authors report on the performance of two small field of view, compact gamma cameras working in single photon counting in planar imaging tests at 122 and 140 keV. The first camera is based on a LaBr3: Ce scintillator continuous crystal (49 x 49 x 5 mm3) assembled with a flat panel multianode photomultiplier tube with parallel readout. The second one belongs to the class of semiconductor hybrid pixel detectors, specifically, a CdTe pixel detector (14 x 14 x 1 mm3) with 256 x 256 square pixels and a pitch of 55 microm, read out by a CMOS single photon counting integrated circuit of the Medipix2 series. The scintillation camera was operated with selectable energy window while the CdTe camera was operated with a single low-energy detection threshold of about 20 keV, i.e., without energy discrimination. The detectors were coupled to pinhole or parallel-hole high-resolution collimators. The evaluation of their overall performance in basic imaging tasks is presented through measurements of their detection efficiency, intrinsic spatial resolution, noise, image SNR, and contrast recovery. The scintillation and CdTe cameras showed, respectively, detection efficiencies at 122 keV of 83% and 45%, intrinsic spatial resolutions of 0.9 mm and 75 microm, and total background noises of 40.5 and 1.6 cps. Imaging tests with high-resolution parallel-hole and pinhole collimators are also reported.

  5. Photon-counting image sensors

    CERN Document Server

    Teranishi, Nobukazu; Theuwissen, Albert; Stoppa, David; Charbon, Edoardo

    2017-01-01

    The field of photon-counting image sensors is advancing rapidly with the development of various solid-state image sensor technologies including single photon avalanche detectors (SPADs) and deep-sub-electron read noise CMOS image sensor pixels. This foundational platform technology will enable opportunities for new imaging modalities and instrumentation for science and industry, as well as new consumer applications. Papers discussing various photon-counting image sensor technologies and selected new applications are presented in this all-invited Special Issue.

  6. Photon counting and fluctuation of molecular movement

    International Nuclear Information System (INIS)

    Inohara, Koichi

    1978-01-01

    The direct measurement of the fluctuation of molecular motions, which provides with useful information on the molecular movement, was conducted by introducing photon counting method. The utilization of photon counting makes it possible to treat the molecular system consisting of a small number of molecules like a radioisotope in the detection of a small number of atoms, which are significant in biological systems. This method is based on counting the number of photons of the definite polarization emitted in a definite time interval from the fluorescent molecules excited by pulsed light, which are bound to the marked large molecules found in a definite spatial region. Using the probability of finding a number of molecules oriented in a definite direction in the definite spatial region, the probability of counting a number of photons in a definite time interval can be calculated. Thus the measurable count rate of photons can be related with the fluctuation of molecular movement. The measurement was carried out under the condition, in which the probability of the simultaneous arrival of more than two photons at a detector is less than 1/100. As the experimental results, the resolving power of photon-counting apparatus, the frequency distribution of the number of photons of some definite polarization counted for 1 nanosecond are shown. In the solution, the variance of the number of molecules of 500 on the average is 1200, which was estimated from the experimental data by assuming normal distribution. This departure from the Poisson distribution means that a certain correlation does exist in molecular movement. In solid solution, no significant deviation was observed. The correlation existing in molecular movement can be expressed in terms of the fluctuation of the number of molecules. (Nakai, Y.)

  7. Energy Calibration of a Silicon-Strip Detector for Photon-Counting Spectral CT by Direct Usage of the X-ray Tube Spectrum

    Science.gov (United States)

    Liu, Xuejin; Chen, Han; Bornefalk, Hans; Danielsson, Mats; Karlsson, Staffan; Persson, Mats; Xu, Cheng; Huber, Ben

    2015-02-01

    The variation among energy thresholds in a multibin detector for photon-counting spectral CT can lead to ring artefacts in the reconstructed images. Calibration of the energy thresholds can be used to achieve homogeneous threshold settings or to develop compensation methods to reduce the artefacts. We have developed an energy-calibration method for the different comparator thresholds employed in a photon-counting silicon-strip detector. In our case, this corresponds to specifying the linear relation between the threshold positions in units of mV and the actual deposited photon energies in units of keV. This relation is determined by gain and offset values that differ for different detector channels due to variations in the manufacturing process. Typically, the calibration is accomplished by correlating the peak positions of obtained pulse-height spectra to known photon energies, e.g. with the aid of mono-energetic x rays from synchrotron radiation, radioactive isotopes or fluorescence materials. Instead of mono-energetic x rays, the calibration method presented in this paper makes use of a broad x-ray spectrum provided by commercial x-ray tubes. Gain and offset as the calibration parameters are obtained by a regression analysis that adjusts a simulated spectrum of deposited energies to a measured pulse-height spectrum. Besides the basic photon interactions such as Rayleigh scattering, Compton scattering and photo-electric absorption, the simulation takes into account the effect of pulse pileup, charge sharing and the electronic noise of the detector channels. We verify the method for different detector channels with the aid of a table-top setup, where we find the uncertainty of the keV-value of a calibrated threshold to be between 0.1 and 0.2 keV.

  8. Photon counting detector for the personal radiography inspection system “SIBSCAN”

    Energy Technology Data Exchange (ETDEWEB)

    Babichev, E.A.; Baru, S.E. [Budker Institute of Nuclear Physics, Lavrentiev ave. 11, Novosibirsk 630090 (Russian Federation); Grigoriev, D.N. [Budker Institute of Nuclear Physics, Lavrentiev ave. 11, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova st. 2, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20 Prospekt K. Marksa, Novosibirsk 630073 (Russian Federation); Leonov, V.V. [Budker Institute of Nuclear Physics, Lavrentiev ave. 11, Novosibirsk 630090 (Russian Federation); Oleynikov, V.P. [Budker Institute of Nuclear Physics, Lavrentiev ave. 11, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova st. 2, Novosibirsk 630090 (Russian Federation); Porosev, V.V., E-mail: porosev@inp.nsk.su [Budker Institute of Nuclear Physics, Lavrentiev ave. 11, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova st. 2, Novosibirsk 630090 (Russian Federation); Savinov, G.A. [Budker Institute of Nuclear Physics, Lavrentiev ave. 11, Novosibirsk 630090 (Russian Federation)

    2017-02-11

    X-ray detectors operating in the energy integrating mode are successfully used in many different applications. Nevertheless the direct photon counting detectors, having the superior parameters in comparison with the integrating ones, are rarely used yet. One of the reasons for this is the low value of the electrical signal generated by a detected photon. Silicon photomultiplier (SiPM) based scintillation counters have a high detection efficiency, high electronic gain and compact dimensions. This makes them a very attractive candidate to replace routinely used detectors in many fields. More than 10 years ago the digital scanning radiography system based on multistrip ionization chamber (MIC) was suggested at Budker Institute of Nuclear Physics. The detector demonstrates excellent radiation resistance and parameter stability after 5 year operations and an imaging of up to 1000 persons per day. Currently, the installations operate at several Russian airports and at subway stations in some cities. At the present time we design a new detector operating in the photon counting mode, having superior parameters than the gas one, based on scintillator – SiPM assemblies. This detector has close to zero noise, higher quantum efficiency and a count rate capability of more than 5 MHz per channel (20% losses), which leads to better image quality and improved detection capability. The suggested detector technology could be expanded to medical applications.

  9. Photon counting detector for the personal radiography inspection system “SIBSCAN”

    International Nuclear Information System (INIS)

    Babichev, E.A.; Baru, S.E.; Grigoriev, D.N.; Leonov, V.V.; Oleynikov, V.P.; Porosev, V.V.; Savinov, G.A.

    2017-01-01

    X-ray detectors operating in the energy integrating mode are successfully used in many different applications. Nevertheless the direct photon counting detectors, having the superior parameters in comparison with the integrating ones, are rarely used yet. One of the reasons for this is the low value of the electrical signal generated by a detected photon. Silicon photomultiplier (SiPM) based scintillation counters have a high detection efficiency, high electronic gain and compact dimensions. This makes them a very attractive candidate to replace routinely used detectors in many fields. More than 10 years ago the digital scanning radiography system based on multistrip ionization chamber (MIC) was suggested at Budker Institute of Nuclear Physics. The detector demonstrates excellent radiation resistance and parameter stability after 5 year operations and an imaging of up to 1000 persons per day. Currently, the installations operate at several Russian airports and at subway stations in some cities. At the present time we design a new detector operating in the photon counting mode, having superior parameters than the gas one, based on scintillator – SiPM assemblies. This detector has close to zero noise, higher quantum efficiency and a count rate capability of more than 5 MHz per channel (20% losses), which leads to better image quality and improved detection capability. The suggested detector technology could be expanded to medical applications.

  10. Photon counting with small pore microchannel plates

    International Nuclear Information System (INIS)

    Martindale, A.; Lapington, J.S.; Fraser, G.W.

    2007-01-01

    We describe the operation of microchannel plates (MCPs) with 3.2μm diameter channels as photon counting detectors of soft X-rays. Gain and temporal resolution measurements are compared with theoretical scaling laws for channel diameter. A minimum pulse width of 264ps is observed for a two stage multiplier at a total bias voltage of ∼1930V

  11. Reduction of CMOS Image Sensor Read Noise to Enable Photon Counting.

    Science.gov (United States)

    Guidash, Michael; Ma, Jiaju; Vogelsang, Thomas; Endsley, Jay

    2016-04-09

    Recent activity in photon counting CMOS image sensors (CIS) has been directed to reduction of read noise. Many approaches and methods have been reported. This work is focused on providing sub 1 e(-) read noise by design and operation of the binary and small signal readout of photon counting CIS. Compensation of transfer gate feed-through was used to provide substantially reduced CDS time and source follower (SF) bandwidth. SF read noise was reduced by a factor of 3 with this method. This method can be applied broadly to CIS devices to reduce the read noise for small signals to enable use as a photon counting sensor.

  12. Musculoskeletal imaging with a prototype photon-counting detector.

    Science.gov (United States)

    Gruber, M; Homolka, P; Chmeissani, M; Uffmann, M; Pretterklieber, M; Kainberger, F

    2012-01-01

    To test a digital imaging X-ray device based on the direct capture of X-ray photons with pixel detectors, which are coupled with photon-counting readout electronics. The chip consists of a matrix of 256 × 256 pixels with a pixel pitch of 55 μm. A monolithic image of 11.2 cm × 7 cm was obtained by the consecutive displacement approach. Images of embalmed anatomical specimens of eight human hands were obtained at four different dose levels (skin dose 2.4, 6, 12, 25 μGy) with the new detector, as well as with a flat-panel detector. The overall rating scores for the evaluated anatomical regions ranged from 5.23 at the lowest dose level, 6.32 at approximately 6 μGy, 6.70 at 12 μGy, to 6.99 at the highest dose level with the photon-counting system. The corresponding rating scores for the flat-panel detector were 3.84, 5.39, 6.64, and 7.34. When images obtained at the same dose were compared, the new system outperformed the conventional DR system at the two lowest dose levels. At the higher dose levels, there were no significant differences between the two systems. The photon-counting detector has great potential to obtain musculoskeletal images of excellent quality at very low dose levels.

  13. Photon Counting Using Edge-Detection Algorithm

    Science.gov (United States)

    Gin, Jonathan W.; Nguyen, Danh H.; Farr, William H.

    2010-01-01

    New applications such as high-datarate, photon-starved, free-space optical communications require photon counting at flux rates into gigaphoton-per-second regimes coupled with subnanosecond timing accuracy. Current single-photon detectors that are capable of handling such operating conditions are designed in an array format and produce output pulses that span multiple sample times. In order to discern one pulse from another and not to overcount the number of incoming photons, a detection algorithm must be applied to the sampled detector output pulses. As flux rates increase, the ability to implement such a detection algorithm becomes difficult within a digital processor that may reside within a field-programmable gate array (FPGA). Systems have been developed and implemented to both characterize gigahertz bandwidth single-photon detectors, as well as process photon count signals at rates into gigaphotons per second in order to implement communications links at SCPPM (serial concatenated pulse position modulation) encoded data rates exceeding 100 megabits per second with efficiencies greater than two bits per detected photon. A hardware edge-detection algorithm and corresponding signal combining and deserialization hardware were developed to meet these requirements at sample rates up to 10 GHz. The photon discriminator deserializer hardware board accepts four inputs, which allows for the ability to take inputs from a quadphoton counting detector, to support requirements for optical tracking with a reduced number of hardware components. The four inputs are hardware leading-edge detected independently. After leading-edge detection, the resultant samples are ORed together prior to deserialization. The deserialization is performed to reduce the rate at which data is passed to a digital signal processor, perhaps residing within an FPGA. The hardware implements four separate analog inputs that are connected through RF connectors. Each analog input is fed to a high-speed 1

  14. Advanced photon counting applications, methods, instrumentation

    CERN Document Server

    Kapusta, Peter; Erdmann, Rainer

    2015-01-01

    This volume focuses on Time-Correlated Single Photon Counting (TCSPC), a powerful tool allowing luminescence lifetime measurements to be made with high temporal resolution, even on single molecules. Combining spectrum and lifetime provides a "fingerprint" for identifying such molecules in the presence of a background. Used together with confocal detection, this permits single-molecule spectroscopy and microscopy in addition to ensemble measurements, opening up an enormous range of hot life science applications such as fluorescence lifetime imaging (FLIM) and measurement of Förster Resonant Energy Transfer (FRET) for the investigation of protein folding and interaction. Several technology-related chapters present both the basics and current state-of-the-art, in particular of TCSPC electronics, photon detectors and lasers. The remaining chapters cover a broad range of applications and methodologies for experiments and data analysis, including the life sciences, defect centers in diamonds, super-resolution micr...

  15. The intensity detection of single-photon detectors based on photon counting probability density statistics

    International Nuclear Information System (INIS)

    Zhang Zijing; Song Jie; Zhao Yuan; Wu Long

    2017-01-01

    Single-photon detectors possess the ultra-high sensitivity, but they cannot directly respond to signal intensity. Conventional methods adopt sampling gates with fixed width and count the triggered number of sampling gates, which is capable of obtaining photon counting probability to estimate the echo signal intensity. In this paper, we not only count the number of triggered sampling gates, but also record the triggered time position of photon counting pulses. The photon counting probability density distribution is obtained through the statistics of a series of the triggered time positions. Then Minimum Variance Unbiased Estimation (MVUE) method is used to estimate the echo signal intensity. Compared with conventional methods, this method can improve the estimation accuracy of echo signal intensity due to the acquisition of more detected information. Finally, a proof-of-principle laboratory system is established. The estimation accuracy of echo signal intensity is discussed and a high accuracy intensity image is acquired under low-light level environments. (paper)

  16. Characterization of photon-counting multislit breast tomosynthesis.

    Science.gov (United States)

    Berggren, Karl; Cederström, Björn; Lundqvist, Mats; Fredenberg, Erik

    2018-02-01

    It has been shown that breast tomosynthesis may improve sensitivity and specificity compared to two-dimensional mammography, resulting in increased detection-rate of cancers or lowered call-back rates. The purpose of this study is to characterize a spectral photon-counting multislit breast tomosynthesis system that is able to do single-scan spectral imaging with multiple collimated x-ray beams. The system differs in many aspects compared to conventional tomosynthesis using energy-integrating flat-panel detectors. The investigated system was a prototype consisting of a dual-threshold photon-counting detector with 21 collimated line detectors scanning across the compressed breast. A review of the system is done in terms of detector, acquisition geometry, and reconstruction methods. Three reconstruction methods were used, simple back-projection, filtered back-projection and an iterative algebraic reconstruction technique. The image quality was evaluated by measuring the modulation transfer-function (MTF), normalized noise-power spectrum, detective quantum-efficiency (DQE), and artifact spread-function (ASF) on reconstructed spectral tomosynthesis images for a total-energy bin (defined by a low-energy threshold calibrated to remove electronic noise) and for a high-energy bin (with a threshold calibrated to split the spectrum in roughly equal parts). Acquisition was performed using a 29 kVp W/Al x-ray spectrum at a 0.24 mGy exposure. The difference in MTF between the two energy bins was negligible, that is, there was no energy dependence on resolution. The MTF dropped to 50% at 1.5 lp/mm to 2.3 lp/mm in the scan direction and 2.4 lp/mm to 3.3 lp/mm in the slit direction, depending on the reconstruction method. The full width at half maximum of the ASF was found to range from 13.8 mm to 18.0 mm for the different reconstruction methods. The zero-frequency DQE of the system was found to be 0.72. The fraction of counts in the high-energy bin was measured to be 59% of the

  17. Si-strip photon counting detectors for contrast-enhanced spectral mammography

    Science.gov (United States)

    Chen, Buxin; Reiser, Ingrid; Wessel, Jan C.; Malakhov, Nail; Wawrzyniak, Gregor; Hartsough, Neal E.; Gandhi, Thulasi; Chen, Chin-Tu; Iwanczyk, Jan S.; Barber, William C.

    2015-08-01

    We report on the development of silicon strip detectors for energy-resolved clinical mammography. Typically, X-ray integrating detectors based on scintillating cesium iodide CsI(Tl) or amorphous selenium (a-Se) are used in most commercial systems. Recently, mammography instrumentation has been introduced based on photon counting Si strip detectors. The required performance for mammography in terms of the output count rate, spatial resolution, and dynamic range must be obtained with sufficient field of view for the application, thus requiring the tiling of pixel arrays and particular scanning techniques. Room temperature Si strip detector, operating as direct conversion x-ray sensors, can provide the required speed when connected to application specific integrated circuits (ASICs) operating at fast peaking times with multiple fixed thresholds per pixel, provided that the sensors are designed for rapid signal formation across the X-ray energy ranges of the application. We present our methods and results from the optimization of Si-strip detectors for contrast enhanced spectral mammography. We describe the method being developed for quantifying iodine contrast using the energy-resolved detector with fixed thresholds. We demonstrate the feasibility of the method by scanning an iodine phantom with clinically relevant contrast levels.

  18. Photon counting arrays for AO wavefront sensors

    CERN Document Server

    Vallerga, J; McPhate, J; Mikulec, Bettina; Clark, Allan G; Siegmund, O; CERN. Geneva

    2005-01-01

    Future wavefront sensors for AO on large telescopes will require a large number of pixels and must operate at high frame rates. Unfortunately for CCDs, there is a readout noise penalty for operating faster, and this noise can add up rather quickly when considering the number of pixels required for the extended shape of a sodium laser guide star observed with a large telescope. Imaging photon counting detectors have zero readout noise and many pixels, but have suffered in the past with low QE at the longer wavelengths (>500 nm). Recent developments in GaAs photocathode technology, CMOS ASIC readouts and FPGA processing electronics have resulted in noiseless WFS detector designs that are competitive with silicon array detectors, though at ~40% the QE of CCDs. We review noiseless array detectors and compare their centroiding performance with CCDs using the best available characteristics of each. We show that for sub-aperture binning of 6x6 and greater that noiseless detectors have a smaller centroid error at flu...

  19. Quantum Biometrics with Retinal Photon Counting

    Science.gov (United States)

    Loulakis, M.; Blatsios, G.; Vrettou, C. S.; Kominis, I. K.

    2017-10-01

    It is known that the eye's scotopic photodetectors, rhodopsin molecules, and their associated phototransduction mechanism leading to light perception, are efficient single-photon counters. We here use the photon-counting principles of human rod vision to propose a secure quantum biometric identification based on the quantum-statistical properties of retinal photon detection. The photon path along the human eye until its detection by rod cells is modeled as a filter having a specific transmission coefficient. Precisely determining its value from the photodetection statistics registered by the conscious observer is a quantum parameter estimation problem that leads to a quantum secure identification method. The probabilities for false-positive and false-negative identification of this biometric technique can readily approach 10-10 and 10-4, respectively. The security of the biometric method can be further quantified by the physics of quantum measurements. An impostor must be able to perform quantum thermometry and quantum magnetometry with energy resolution better than 10-9ℏ , in order to foil the device by noninvasively monitoring the biometric activity of a user.

  20. Real-time computational photon-counting LiDAR

    Science.gov (United States)

    Edgar, Matthew; Johnson, Steven; Phillips, David; Padgett, Miles

    2018-03-01

    The availability of compact, low-cost, and high-speed MEMS-based spatial light modulators has generated widespread interest in alternative sampling strategies for imaging systems utilizing single-pixel detectors. The development of compressed sensing schemes for real-time computational imaging may have promising commercial applications for high-performance detectors, where the availability of focal plane arrays is expensive or otherwise limited. We discuss the research and development of a prototype light detection and ranging (LiDAR) system via direct time of flight, which utilizes a single high-sensitivity photon-counting detector and fast-timing electronics to recover millimeter accuracy three-dimensional images in real time. The development of low-cost real time computational LiDAR systems could have importance for applications in security, defense, and autonomous vehicles.

  1. Cascaded systems analysis of photon counting detectors.

    Science.gov (United States)

    Xu, J; Zbijewski, W; Gang, G; Stayman, J W; Taguchi, K; Lundqvist, M; Fredenberg, E; Carrino, J A; Siewerdsen, J H

    2014-10-01

    Photon counting detectors (PCDs) are an emerging technology with applications in spectral and low-dose radiographic and tomographic imaging. This paper develops an analytical model of PCD imaging performance, including the system gain, modulation transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). A cascaded systems analysis model describing the propagation of quanta through the imaging chain was developed. The model was validated in comparison to the physical performance of a silicon-strip PCD implemented on an experimental imaging bench. The signal response, MTF, and NPS were measured and compared to theory as a function of exposure conditions (70 kVp, 1-7 mA), detector threshold, and readout mode (i.e., the option for coincidence detection). The model sheds new light on the dependence of spatial resolution, charge sharing, and additive noise effects on threshold selection and was used to investigate the factors governing PCD performance, including the fundamental advantages and limitations of PCDs in comparison to energy-integrating detectors (EIDs) in the linear regime for which pulse pileup can be ignored. The detector exhibited highly linear mean signal response across the system operating range and agreed well with theoretical prediction, as did the system MTF and NPS. The DQE analyzed as a function of kilovolt (peak), exposure, detector threshold, and readout mode revealed important considerations for system optimization. The model also demonstrated the important implications of false counts from both additive electronic noise and charge sharing and highlighted the system design and operational parameters that most affect detector performance in the presence of such factors: for example, increasing the detector threshold from 0 to 100 (arbitrary units of pulse height threshold roughly equivalent to 0.5 and 6 keV energy threshold, respectively), increased the f50 (spatial-frequency at which the MTF falls to a value of

  2. Cascaded systems analysis of photon counting detectors

    International Nuclear Information System (INIS)

    Xu, J.; Zbijewski, W.; Gang, G.; Stayman, J. W.; Taguchi, K.; Carrino, J. A.; Lundqvist, M.; Fredenberg, E.; Siewerdsen, J. H.

    2014-01-01

    Purpose: Photon counting detectors (PCDs) are an emerging technology with applications in spectral and low-dose radiographic and tomographic imaging. This paper develops an analytical model of PCD imaging performance, including the system gain, modulation transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). Methods: A cascaded systems analysis model describing the propagation of quanta through the imaging chain was developed. The model was validated in comparison to the physical performance of a silicon-strip PCD implemented on an experimental imaging bench. The signal response, MTF, and NPS were measured and compared to theory as a function of exposure conditions (70 kVp, 1–7 mA), detector threshold, and readout mode (i.e., the option for coincidence detection). The model sheds new light on the dependence of spatial resolution, charge sharing, and additive noise effects on threshold selection and was used to investigate the factors governing PCD performance, including the fundamental advantages and limitations of PCDs in comparison to energy-integrating detectors (EIDs) in the linear regime for which pulse pileup can be ignored. Results: The detector exhibited highly linear mean signal response across the system operating range and agreed well with theoretical prediction, as did the system MTF and NPS. The DQE analyzed as a function of kilovolt (peak), exposure, detector threshold, and readout mode revealed important considerations for system optimization. The model also demonstrated the important implications of false counts from both additive electronic noise and charge sharing and highlighted the system design and operational parameters that most affect detector performance in the presence of such factors: for example, increasing the detector threshold from 0 to 100 (arbitrary units of pulse height threshold roughly equivalent to 0.5 and 6 keV energy threshold, respectively), increased the f 50 (spatial-frequency at

  3. Cascaded systems analysis of photon counting detectors

    Energy Technology Data Exchange (ETDEWEB)

    Xu, J.; Zbijewski, W.; Gang, G.; Stayman, J. W. [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Taguchi, K.; Carrino, J. A. [Russell H. Morgan Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Lundqvist, M.; Fredenberg, E. [Philips Healthcare, Solna 171 41 (Sweden); Siewerdsen, J. H., E-mail: jeff.siewerdsen@jhu.edu [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Russell H. Morgan Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States)

    2014-10-15

    Purpose: Photon counting detectors (PCDs) are an emerging technology with applications in spectral and low-dose radiographic and tomographic imaging. This paper develops an analytical model of PCD imaging performance, including the system gain, modulation transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). Methods: A cascaded systems analysis model describing the propagation of quanta through the imaging chain was developed. The model was validated in comparison to the physical performance of a silicon-strip PCD implemented on an experimental imaging bench. The signal response, MTF, and NPS were measured and compared to theory as a function of exposure conditions (70 kVp, 1–7 mA), detector threshold, and readout mode (i.e., the option for coincidence detection). The model sheds new light on the dependence of spatial resolution, charge sharing, and additive noise effects on threshold selection and was used to investigate the factors governing PCD performance, including the fundamental advantages and limitations of PCDs in comparison to energy-integrating detectors (EIDs) in the linear regime for which pulse pileup can be ignored. Results: The detector exhibited highly linear mean signal response across the system operating range and agreed well with theoretical prediction, as did the system MTF and NPS. The DQE analyzed as a function of kilovolt (peak), exposure, detector threshold, and readout mode revealed important considerations for system optimization. The model also demonstrated the important implications of false counts from both additive electronic noise and charge sharing and highlighted the system design and operational parameters that most affect detector performance in the presence of such factors: for example, increasing the detector threshold from 0 to 100 (arbitrary units of pulse height threshold roughly equivalent to 0.5 and 6 keV energy threshold, respectively), increased the f{sub 50} (spatial

  4. Characterization of a new computer-ready photon counting system

    Science.gov (United States)

    Andor, Gyorgy

    1998-08-01

    The photon-counting system seems to be the best solution for extremely low optical power measurements. The Hamamatsu HC135 photon counting module has a built-in high-voltage power supply amplifier, discriminator, micro-controller with an RS232 serial output. It requires only a +5V supply voltage and an IBM PC or compatible computer to run. The system is supplied with an application software. This talk is about the testing of the device.

  5. Three-dimensional passive sensing photon counting for object classification

    Science.gov (United States)

    Yeom, Seokwon; Javidi, Bahram; Watson, Edward

    2007-04-01

    In this keynote address, we address three-dimensional (3D) distortion-tolerant object recognition using photon-counting integral imaging (II). A photon-counting linear discriminant analysis (LDA) is discussed for classification of photon-limited images. We develop a compact distortion-tolerant recognition system based on the multiple-perspective imaging of II. Experimental and simulation results have shown that a low level of photons is sufficient to classify out-of-plane rotated objects.

  6. Multiple-Event, Single-Photon Counting Imaging Sensor

    Science.gov (United States)

    Zheng, Xinyu; Cunningham, Thomas J.; Sun, Chao; Wang, Kang L.

    2011-01-01

    The single-photon counting imaging sensor is typically an array of silicon Geiger-mode avalanche photodiodes that are monolithically integrated with CMOS (complementary metal oxide semiconductor) readout, signal processing, and addressing circuits located in each pixel and the peripheral area of the chip. The major problem is its single-event method for photon count number registration. A single-event single-photon counting imaging array only allows registration of up to one photon count in each of its pixels during a frame time, i.e., the interval between two successive pixel reset operations. Since the frame time can t be too short, this will lead to very low dynamic range and make the sensor merely useful for very low flux environments. The second problem of the prior technique is a limited fill factor resulting from consumption of chip area by the monolithically integrated CMOS readout in pixels. The resulting low photon collection efficiency will substantially ruin any benefit gained from the very sensitive single-photon counting detection. The single-photon counting imaging sensor developed in this work has a novel multiple-event architecture, which allows each of its pixels to register as more than one million (or more) photon-counting events during a frame time. Because of a consequently boosted dynamic range, the imaging array of the invention is capable of performing single-photon counting under ultra-low light through high-flux environments. On the other hand, since the multiple-event architecture is implemented in a hybrid structure, back-illumination and close-to-unity fill factor can be realized, and maximized quantum efficiency can also be achieved in the detector array.

  7. Tutorial on X-ray photon counting detector characterization.

    Science.gov (United States)

    Ren, Liqiang; Zheng, Bin; Liu, Hong

    2018-01-01

    Recent advances in photon counting detection technology have led to significant research interest in X-ray imaging. As a tutorial level review, this paper covers a wide range of aspects related to X-ray photon counting detector characterization. The tutorial begins with a detailed description of the working principle and operating modes of a pixelated X-ray photon counting detector with basic architecture and detection mechanism. Currently available methods and techniques for charactering major aspects including energy response, noise floor, energy resolution, count rate performance (detector efficiency), and charge sharing effect of photon counting detectors are comprehensively reviewed. Other characterization aspects such as point spread function (PSF), line spread function (LSF), contrast transfer function (CTF), modulation transfer function (MTF), noise power spectrum (NPS), detective quantum efficiency (DQE), bias voltage, radiation damage, and polarization effect are also remarked. A cadmium telluride (CdTe) pixelated photon counting detector is employed for part of the characterization demonstration and the results are presented. This review can serve as a tutorial for X-ray imaging researchers and investigators to understand, operate, characterize, and optimize photon counting detectors for a variety of applications.

  8. ON THE USE OF SHOT NOISE FOR PHOTON COUNTING

    Energy Technology Data Exchange (ETDEWEB)

    Zmuidzinas, Jonas, E-mail: jonas@caltech.edu [Division of Physics, Mathematics, and Astronomy, California Institute Institute of Technology, Pasadena, CA 91125 (United States)

    2015-11-01

    Lieu et al. have recently claimed that it is possible to substantially improve the sensitivity of radio-astronomical observations. In essence, their proposal is to make use of the intensity of the photon shot noise as a measure of the photon arrival rate. Lieu et al. provide a detailed quantum-mechanical calculation of a proposed measurement scheme that uses two detectors and conclude that this scheme avoids the sensitivity degradation that is associated with photon bunching. If correct, this result could have a profound impact on radio astronomy. Here I present a detailed analysis of the sensitivity attainable using shot-noise measurement schemes that use either one or two detectors, and demonstrate that neither scheme can avoid the photon bunching penalty. I perform both semiclassical and fully quantum calculations of the sensitivity, obtaining consistent results, and provide a formal proof of the equivalence of these two approaches. These direct calculations are furthermore shown to be consistent with an indirect argument based on a correlation method that establishes an independent limit to the sensitivity of shot-noise measurement schemes. Furthermore, these calculations are directly applicable to the regime of interest identified by Lieu et al. Collectively, these results conclusively demonstrate that the photon-bunching sensitivity penalty applies to shot-noise measurement schemes just as it does to ordinary photon counting, in contradiction to the fundamental claim made by Lieu et al. The source of this contradiction is traced to a logical fallacy in their argument.

  9. Estimation of atomic interaction parameters by photon counting

    DEFF Research Database (Denmark)

    Kiilerich, Alexander Holm; Mølmer, Klaus

    2014-01-01

    Detection of radiation signals is at the heart of precision metrology and sensing. In this article we show how the fluctuations in photon counting signals can be exploited to optimally extract information about the physical parameters that govern the dynamics of the emitter. For a simple two......-level emitter subject to photon counting, we show that the Fisher information and the Cram\\'er- Rao sensitivity bound based on the full detection record can be evaluated from the waiting time distribution in the fluorescence signal which can, in turn, be calculated for both perfect and imperfect detectors...

  10. Optimization of time-correlated single photon counting spectrometer

    International Nuclear Information System (INIS)

    Zhang Xiufeng; Du Haiying; Sun Jinsheng

    2011-01-01

    The paper proposes a performance improving scheme for the conventional time-correlated single photon counting spectrometer and develops a high speed data acquisition card based on PCI bus and FPGA technologies. The card is used to replace the multi-channel analyzer to improve the capability and decrease the volume of the spectrometer. The process of operation is introduced along with the integration of the spectrometer system. Many standard samples are measured. The experimental results show that the sensitivity of the spectrometer is single photon counting, and the time resolution of fluorescence lifetime measurement can be picosecond level. The instrument could measure the time-resolved spectroscopy. (authors)

  11. Fast pulse discriminator for photon counting at high photon densities

    International Nuclear Information System (INIS)

    Benoit, R.; Pedrini, A.

    1977-03-01

    A fast tunnel diode discriminator for photon counting up to 200MHz count frequency is described. The tunnel diode is operated on its apparent I.V. characteristics displayed when the diode is driven into its oscillating region. The pulse shaper-discriminator is completely D.C. coupled in order to avoid base-line shift at high pulse rates

  12. The Goddard Integral Field Spectrograph at Apache Point Observatory: Current Status and Progress Towards Photon Counting

    Science.gov (United States)

    McElwain, Michael W.; Grady, Carol A.; Bally, John; Brinkmann, Jonathan V.; Bubeck, James; Gong, Qian; Hilton, George M.; Ketzeback, William F.; Lindler, Don; Llop Sayson, Jorge; Malatesta, Michael A.; Norton, Timothy; Rauscher, Bernard J.; Rothe, Johannes; Straka, Lorrie; Wilkins, Ashlee N.; Wisniewski, John P.; Woodgate, Bruce E.; York, Donald G.

    2015-01-01

    We present the current status and progress towards photon counting with the Goddard Integral Field Spectrograph (GIFS), a new instrument at the Apache Point Observatory's ARC 3.5m telescope. GIFS is a visible light imager and integral field spectrograph operating from 400-1000 nm over a 2.8' x 2.8' and 14' x 14' field of view, respectively. As an IFS, GIFS obtains over 1000 spectra simultaneously and its data reduction pipeline reconstructs them into an image cube that has 32 x 32 spatial elements and more than 200 spectral channels. The IFS mode can be applied to a wide variety of science programs including exoplanet transit spectroscopy, protostellar jets, the galactic interstellar medium probed by background quasars, Lyman-alpha emission line objects, and spectral imaging of galactic winds. An electron-multiplying CCD (EMCCD) detector enables photon counting in the high spectral resolution mode to be demonstrated at the ARC 3.5m in early 2015. The EMCCD work builds upon successful operational and characterization tests that have been conducted in the IFS laboratory at NASA Goddard. GIFS sets out to demonstrate an IFS photon-counting capability on-sky in preparation for future exoplanet direct imaging missions such as the AFTA-Coronagraph, Exo-C, and ATLAST mission concepts. This work is supported by the NASA APRA program under RTOP 10-APRA10-0103.

  13. Direct measurement of tritium in urine by liquid scintillation method

    International Nuclear Information System (INIS)

    Zhang Caihong; Wen Qinghua; Chen Kefei; Li Huaixin

    1999-01-01

    The author introduces the method for direct measurement of tritium concentration in urine using liquid scintillation. Effects of sampling containers, store patterns and storage time are studied. Meanwhile, results of two methods are compared with direct measurement method and oxidation distillation method. The results shows that direct measurement method is a economic and simple method, which can meet the need of determination of urine tritium for NPP workers. There is no significant difference compared with the data obtained by oxidation distillation method

  14. 15 Mcps photon-counting X-ray computed tomography system using a ZnO-MPPC detector and its application to gadolinium imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Eiichi, E-mail: dresato@iwate-med.ac.jp [Department of Physics, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba, Iwate 028-3694 (Japan); Sugimura, Shigeaki [Tokyo Denpa Co. Ltd., 82-5 Ueno, Ichinohe, Iwate 028-5321 (Japan); Endo, Haruyuki [Iwate Industrial Research Insutitute 3, 3-35-2 Shinden, Iioka, Morioka, Iwate 020-0852 (Japan); Oda, Yasuyuki [Department of Physics, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba, Iwate 028-3694 (Japan); Abudurexiti, Abulajiang [Faculty of Software and Information Science, Iwate Prefectural University, 152-52 Sugo, Takizawa, Iwate 020-0193 (Japan); Hagiwara, Osahiko; Osawa, Akihiro; Matsukiyo, Hiroshi; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya [3rd Department of Surgery, Toho University School of Medicine, 2-17-6 Ohashi, Meguro-ku, Tokyo 153-8515 (Japan); Sato, Shigehiro [Department of Microbiology, School of Medicine, Iwate Medical University, 19-1 Uchimaru, Morioka, Iwate 020-0023 (Japan); Ogawa, Akira [Department of Neurosurgery, School of Medicine, Iwate Medical University, 19-1 Uchimaru, Morioka, Iwate 020-0023 (Japan); Onagawa, Jun [Department of Electronics, Faculty of Engineering, Tohoku Gakuin University, 1-13-1 Chuo, Tagajo, Miyagi 985-8537 (Japan)

    2012-01-15

    15 Mcps photon-counting X-ray computed tomography (CT) system is a first-generation type and consists of an X-ray generator, a turntable, a translation stage, a two-stage controller, a detector consisting of a 2 mm-thick zinc-oxide (ZnO) single-crystal scintillator and an MPPC (multipixel photon counter) module, a counter card (CC), and a personal computer (PC). High-speed photon counting was carried out using the detector in the X-ray CT system. The maximum count rate was 15 Mcps (mega counts per second) at a tube voltage of 100 kV and a tube current of 1.95 mA. Tomography is accomplished by repeated translations and rotations of an object, and projection curves of the object are obtained by the translation. The pulses of the event signal from the module are counted by the CC in conjunction with the PC. The minimum exposure time for obtaining a tomogram was 15 min, and photon-counting CT was accomplished using gadolinium-based contrast media. - Highlights: Black-Right-Pointing-Pointer We developed a first-generation 15 Mcps photon-counting X-ray computed tomography (CT) system. Black-Right-Pointing-Pointer High-speed photon counting was carried out using a zinc-oxide (ZnO) single-crystal scintillator and an MPPC (multipixel photon counter) module in the X-ray CT system. Black-Right-Pointing-Pointer Tomography is accomplished by repeated translations and rotations of an object. Black-Right-Pointing-Pointer The minimum exposure time for obtaining a tomogram was 15 min. Black-Right-Pointing-Pointer The photon-counting CT was accomplished using gadolinium-based contrast media.

  15. Photon-counting multifactor optical encryption and authentication

    International Nuclear Information System (INIS)

    Pérez-Cabré, E; Millán, M S; Mohammed, E A; Saadon, H L

    2015-01-01

    The multifactor optical encryption authentication method [Opt. Lett., 31 721-3 (2006)] reinforces optical security by allowing the simultaneous authentication of up to four factors. In this work, the photon-counting imaging technique is applied to the multifactor encrypted function so that a sparse phase-only distribution is generated for the encrypted data. The integration of both techniques permits an increased capacity for signal hiding with simultaneous data reduction for better fulfilling the general requirements of protection, storage and transmission. Cryptanalysis of the proposed method is carried out in terms of chosen-plaintext and chosen-ciphertext attacks. Although the multifactor authentication process is not substantially altered by those attacks, its integration with the photon-counting imaging technique prevents from possible partial disclosure of any encrypted factor, thus increasing the security level of the overall process. Numerical experiments and results are provided and discussed. (paper)

  16. Conditionally Teleported States Using Optical Squeezers and Photon Counting

    Institute of Scientific and Technical Information of China (English)

    FAN Hong-Yi; FAN Yue; CHENG Hai-Ling

    2002-01-01

    By virtue of the neat expression of the two-mode squeezing operator in the Einstein,Podolsky and Rosen entangled state representation,we provide a new approach for discussing the teleportation scheme using optical squeezers and photon counting devices.We derive the explicit form of the teleported states,so that the conditional property of teleportation and teleportation fidelity of this protocol can be scen more clcarly.The derivation is concise.

  17. An area efficient readout architecture for photon counting color imaging

    International Nuclear Information System (INIS)

    Lundgren, Jan; O'Nils, Mattias; Oelmann, Bengt; Norlin, Boerje; Abdalla, Suliman

    2007-01-01

    The introduction of several energy levels, namely color imaging, in photon counting X-ray image sensors is a trade-off between circuit complexity and spatial resolution. In this paper, we propose a pixel architecture that has full resolution for the intensity and uses sub-sampling for the energy spectrum. The results show that this sub-sampling pixel architecture produces images with an image quality which is, on average, 2.4 dB (PSNR) higher than those for a single energy range architecture and with half the circuit complexity of that for a full sampling architecture

  18. Scintillators

    International Nuclear Information System (INIS)

    Cusano, D.A.; Holub, F.F.; Prochazka, S.

    1979-01-01

    Scintillator bodies comprising phosphor materials and having high optical translucency with low light absorption, and methods of making the scintillator bodies, are described. Fabrication methods include (a) a hot-pressing process, (b) cold-pressing followed by sintering, (c) controlled cooling from a melt, and (d) hot-forging. The scintillator bodies that result are easily machined to desired shapes and sizes. Suitable phosphors include BaFCl:Eu, LaOBr:Tb, CsI:Tl, CaWO 4 and CdWO 4 . (U.K.)

  19. Ultrafast photon counting applied to resonant scanning STED microscopy.

    Science.gov (United States)

    Wu, Xundong; Toro, Ligia; Stefani, Enrico; Wu, Yong

    2015-01-01

    To take full advantage of fast resonant scanning in super-resolution stimulated emission depletion (STED) microscopy, we have developed an ultrafast photon counting system based on a multigiga sample per second analogue-to-digital conversion chip that delivers an unprecedented 450 MHz pixel clock (2.2 ns pixel dwell time in each scan). The system achieves a large field of view (∼50 × 50 μm) with fast scanning that reduces photobleaching, and advances the time-gated continuous wave STED technology to the usage of resonant scanning with hardware-based time-gating. The assembled system provides superb signal-to-noise ratio and highly linear quantification of light that result in superior image quality. Also, the system design allows great flexibility in processing photon signals to further improve the dynamic range. In conclusion, we have constructed a frontier photon counting image acquisition system with ultrafast readout rate, excellent counting linearity, and with the capacity of realizing resonant-scanning continuous wave STED microscopy with online time-gated detection. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

  20. Novel Photon-Counting Detectors for Free-Space Communication

    Science.gov (United States)

    Krainak, Michael A.; Yang, Guan; Sun, Xiaoli; Lu, Wei; Merritt, Scott; Beck, Jeff

    2016-01-01

    We present performance data for novel photon counting detectors for free space optical communication. NASA GSFC is testing the performance of three novel photon counting detectors 1) a 2x8 mercury cadmium telluride avalanche array made by DRS Inc. 2) a commercial 2880 silicon avalanche photodiode array and 3) a prototype resonant cavity silicon avalanche photodiode array. We will present and compare dark count, photon detection efficiency, wavelength response and communication performance data for these detectors. We discuss system wavelength trades and architectures for optimizing overall communication link sensitivity, data rate and cost performance. The HgCdTe APD array has photon detection efficiencies of greater than 50 were routinely demonstrated across 5 arrays, with one array reaching a maximum PDE of 70. High resolution pixel-surface spot scans were performed and the junction diameters of the diodes were measured. The junction diameter was decreased from 31 m to 25 m resulting in a 2x increase in e-APD gain from 470 on the 2010 array to 1100 on the array delivered to NASA GSFC. Mean single photon SNRs of over 12 were demonstrated at excess noise factors of 1.2-1.3.The commercial silicon APD array has a fast output with rise times of 300ps and pulse widths of 600ps. Received and filtered signals from the entire array are multiplexed onto this single fast output. The prototype resonant cavity silicon APD array is being developed for use at 1 micron wavelength.

  1. Characterization of energy response for photon-counting detectors using x-ray fluorescence

    International Nuclear Information System (INIS)

    Ding, Huanjun; Cho, Hyo-Min; Molloi, Sabee; Barber, William C.; Iwanczyk, Jan S.

    2014-01-01

    Purpose: To investigate the feasibility of characterizing a Si strip photon-counting detector using x-ray fluorescence. Methods: X-ray fluorescence was generated by using a pencil beam from a tungsten anode x-ray tube with 2 mm Al filtration. Spectra were acquired at 90° from the primary beam direction with an energy-resolved photon-counting detector based on an edge illuminated Si strip detector. The distances from the source to target and the target to detector were approximately 19 and 11 cm, respectively. Four different materials, containing silver (Ag), iodine (I), barium (Ba), and gadolinium (Gd), were placed in small plastic containers with a diameter of approximately 0.7 cm for x-ray fluorescence measurements. Linear regression analysis was performed to derive the gain and offset values for the correlation between the measured fluorescence peak center and the known fluorescence energies. The energy resolutions and charge-sharing fractions were also obtained from analytical fittings of the recorded fluorescence spectra. An analytical model, which employed four parameters that can be determined from the fluorescence calibration, was used to estimate the detector response function. Results: Strong fluorescence signals of all four target materials were recorded with the investigated geometry for the Si strip detector. The average gain and offset of all pixels for detector energy calibration were determined to be 6.95 mV/keV and −66.33 mV, respectively. The detector’s energy resolution remained at approximately 2.7 keV for low energies, and increased slightly at 45 keV. The average charge-sharing fraction was estimated to be 36% within the investigated energy range of 20–45 keV. The simulated detector output based on the proposed response function agreed well with the experimental measurement. Conclusions: The performance of a spectral imaging system using energy-resolved photon-counting detectors is very dependent on the energy calibration of the

  2. Polychromatic Iterative Statistical Material Image Reconstruction for Photon-Counting Computed Tomography

    Directory of Open Access Journals (Sweden)

    Thomas Weidinger

    2016-01-01

    Full Text Available This work proposes a dedicated statistical algorithm to perform a direct reconstruction of material-decomposed images from data acquired with photon-counting detectors (PCDs in computed tomography. It is based on local approximations (surrogates of the negative logarithmic Poisson probability function. Exploiting the convexity of this function allows for parallel updates of all image pixels. Parallel updates can compensate for the rather slow convergence that is intrinsic to statistical algorithms. We investigate the accuracy of the algorithm for ideal photon-counting detectors. Complementarily, we apply the algorithm to simulation data of a realistic PCD with its spectral resolution limited by K-escape, charge sharing, and pulse-pileup. For data from both an ideal and realistic PCD, the proposed algorithm is able to correct beam-hardening artifacts and quantitatively determine the material fractions of the chosen basis materials. Via regularization we were able to achieve a reduction of image noise for the realistic PCD that is up to 90% lower compared to material images form a linear, image-based material decomposition using FBP images. Additionally, we find a dependence of the algorithms convergence speed on the threshold selection within the PCD.

  3. Maturing CCD Photon-Counting Technology for Space Flight

    Science.gov (United States)

    Mallik, Udayan; Lyon, Richard; Petrone, Peter; McElwain, Michael; Benford, Dominic; Clampin, Mark; Hicks, Brian

    2015-01-01

    This paper discusses charge blooming and starlight saturation - two potential technical problems - when using an Electron Multiplying Charge Coupled Device (EMCCD) type detector in a high-contrast instrument for imaging exoplanets. These problems especially affect an interferometric type coronagraph - coronagraphs that do not use a mask to physically block starlight in the science channel of the instrument. These problems are presented using images taken with a commercial Princeton Instrument EMCCD camera in the Goddard Space Flight Center's (GSFC), Interferometric Coronagraph facility. In addition, this paper discusses techniques to overcome such problems. This paper also discusses the development and architecture of a Field Programmable Gate Array and Digital-to-Analog Converter based shaped clock controller for a photon-counting EMCCD camera. The discussion contained here will inform high-contrast imaging groups in their work with EMCCD detectors.

  4. Low photon count based digital holography for quadratic phase cryptography.

    Science.gov (United States)

    Muniraj, Inbarasan; Guo, Changliang; Malallah, Ra'ed; Ryle, James P; Healy, John J; Lee, Byung-Geun; Sheridan, John T

    2017-07-15

    Recently, the vulnerability of the linear canonical transform-based double random phase encryption system to attack has been demonstrated. To alleviate this, we present for the first time, to the best of our knowledge, a method for securing a two-dimensional scene using a quadratic phase encoding system operating in the photon-counted imaging (PCI) regime. Position-phase-shifting digital holography is applied to record the photon-limited encrypted complex samples. The reconstruction of the complex wavefront involves four sparse (undersampled) dataset intensity measurements (interferograms) at two different positions. Computer simulations validate that the photon-limited sparse-encrypted data has adequate information to authenticate the original data set. Finally, security analysis, employing iterative phase retrieval attacks, has been performed.

  5. Development and flight testing of UV optimized Photon Counting CCDs

    Science.gov (United States)

    Hamden, Erika T.

    2018-06-01

    I will discuss the latest results from the Hamden UV/Vis Detector Lab and our ongoing work using a UV optimized EMCCD in flight. Our lab is currently testing efficiency and performance of delta-doped, anti-reflection coated EMCCDs, in collaboration with JPL. The lab has been set-up to test quantum efficiency, dark current, clock-induced-charge, and read noise. I will describe our improvements to our circuit boards for lower noise, updates from a new, more flexible NUVU controller, and the integration of an EMCCD in the FIREBall-2 UV spectrograph. I will also briefly describe future plans to conduct radiation testing on delta-doped EMCCDs (both warm, unbiased and cold, biased configurations) thus summer and longer term plans for testing newer photon counting CCDs as I move the HUVD Lab to the University of Arizona in the Fall of 2018.

  6. Advanced time-correlated single photon counting applications

    CERN Document Server

    Becker, Wolfgang

    2015-01-01

    This book is an attempt to bridge the gap between the instrumental principles of multi-dimensional time-correlated single photon counting (TCSPC) and typical applications of the technique. Written by an originator of the technique and by sucessful users, it covers the basic principles of the technique, its interaction with optical imaging methods and its application to a wide range of experimental tasks in life sciences and clinical research. The book is recommended for all users of time-resolved detection techniques in biology, bio-chemistry, spectroscopy of live systems, live cell microscopy, clinical imaging, spectroscopy of single molecules, and other applications that require the detection of low-level light signals at single-photon sensitivity and picosecond time resolution.

  7. Multimode model for projective photon-counting measurements

    International Nuclear Information System (INIS)

    Tualle-Brouri, Rosa; Ourjoumtsev, Alexei; Dantan, Aurelien; Grangier, Philippe; Wubs, Martijn; Soerensen, Anders S.

    2009-01-01

    We present a general model to account for the multimode nature of the quantum electromagnetic field in projective photon-counting measurements. We focus on photon-subtraction experiments, where non-Gaussian states are produced conditionally. These are useful states for continuous-variable quantum-information processing. We present a general method called mode reduction that reduces the multimode model to an effective two-mode problem. We apply this method to a multimode model describing broadband parametric down-conversion, thereby improving the analysis of existing experimental results. The main improvement is that spatial and frequency filters before the photon detector are taken into account explicitly. We find excellent agreement with previously published experimental results, using fewer free parameters than before, and discuss the implications of our analysis for the optimized production of states with negative Wigner functions.

  8. Ultra-fast photon counting with a passive quenching silicon photomultiplier in the charge integration regime

    Science.gov (United States)

    Zhang, Guoqing; Lina, Liu

    2018-02-01

    An ultra-fast photon counting method is proposed based on the charge integration of output electrical pulses of passive quenching silicon photomultipliers (SiPMs). The results of the numerical analysis with actual parameters of SiPMs show that the maximum photon counting rate of a state-of-art passive quenching SiPM can reach ~THz levels which is much larger than that of the existing photon counting devices. The experimental procedure is proposed based on this method. This photon counting regime of SiPMs is promising in many fields such as large dynamic light power detection.

  9. In situ detection of warfarin using time-correlated single-photon counting

    Energy Technology Data Exchange (ETDEWEB)

    Rosengren, Annika M.; Karlsson, Bjoern C.G. [Bioorganic and Biophysical Chemistry Laboratory, School of Natural Sciences, Linnaeus University, SE-391 82 Kalmar (Sweden); Naeslund, Inga; Andersson, Per Ola [Swedish Defence Research Agency, FOI, CBRN Defence and Security, SE-901 82 Umea (Sweden); Nicholls, Ian A., E-mail: ian.a.nicholls@bioorg.uu.se [Bioorganic and Biophysical Chemistry Laboratory, School of Natural Sciences, Linnaeus University, SE-391 82 Kalmar (Sweden); Department of Biochemistry and Organic Chemistry Laboratory, Uppsala University, SE-751 23 Uppsala (Sweden)

    2011-04-01

    Highlights: {yields} Direct in situ measurement of specific isomeric forms of the anticoagulant warfarin. {yields} TCSPC spectroscopy in conjunction with synthetic Sudlow I binding site receptors. {yields} Development of sensor principle for use in clinical and environmental monitoring. -- Abstract: Here we report on a novel method for the direct in situ measurement of specific isomeric forms of the anticoagulant warfarin using time correlated single-photon counting (TCSPC) spectroscopy in conjunction with synthetic Sudlow I binding site receptors. The method is highly robust over the clinically significant concentration range, and demonstrates the potential of the binding site mimics in conjunction with the spectroscopic strategy employed here for the determination of this important pharmaceutical in clinical or even environmental samples.

  10. In situ detection of warfarin using time-correlated single-photon counting

    International Nuclear Information System (INIS)

    Rosengren, Annika M.; Karlsson, Bjoern C.G.; Naeslund, Inga; Andersson, Per Ola; Nicholls, Ian A.

    2011-01-01

    Highlights: → Direct in situ measurement of specific isomeric forms of the anticoagulant warfarin. → TCSPC spectroscopy in conjunction with synthetic Sudlow I binding site receptors. → Development of sensor principle for use in clinical and environmental monitoring. -- Abstract: Here we report on a novel method for the direct in situ measurement of specific isomeric forms of the anticoagulant warfarin using time correlated single-photon counting (TCSPC) spectroscopy in conjunction with synthetic Sudlow I binding site receptors. The method is highly robust over the clinically significant concentration range, and demonstrates the potential of the binding site mimics in conjunction with the spectroscopic strategy employed here for the determination of this important pharmaceutical in clinical or even environmental samples.

  11. High resolution micro-CT of low attenuating organic materials using large area photon-counting detector

    International Nuclear Information System (INIS)

    Kumpová, I.; Jandejsek, I.; Jakůbek, J.; Vopálenský, M.; Vavřík, D.; Fíla, T.; Koudelka, P.; Kytýř, D.; Zlámal, P.; Gantar, A.

    2016-01-01

    To overcome certain limitations of contemporary materials used for bone tissue engineering, such as inflammatory response after implantation, a whole new class of materials based on polysaccharide compounds is being developed. Here, nanoparticulate bioactive glass reinforced gelan-gum (GG-BAG) has recently been proposed for the production of bone scaffolds. This material offers promising biocompatibility properties, including bioactivity and biodegradability, with the possibility of producing scaffolds with directly controlled microgeometry. However, to utilize such a scaffold with application-optimized properties, large sets of complex numerical simulations using the real microgeometry of the material have to be carried out during the development process. Because the GG-BAG is a material with intrinsically very low attenuation to X-rays, its radiographical imaging, including tomographical scanning and reconstructions, with resolution required by numerical simulations might be a very challenging task. In this paper, we present a study on X-ray imaging of GG-BAG samples. High-resolution volumetric images of investigated specimens were generated on the basis of micro-CT measurements using a large area flat-panel detector and a large area photon-counting detector. The photon-counting detector was composed of a 010× 1 matrix of Timepix edgeless silicon pixelated detectors with tiling based on overlaying rows (i.e. assembled so that no gap is present between individual rows of detectors). We compare the results from both detectors with the scanning electron microscopy on selected slices in transversal plane. It has been shown that the photon counting detector can provide approx. 3× better resolution of the details in low-attenuating materials than the integrating flat panel detectors. We demonstrate that employment of a large area photon counting detector is a good choice for imaging of low attenuating materials with the resolution sufficient for numerical

  12. High resolution micro-CT of low attenuating organic materials using large area photon-counting detector

    Science.gov (United States)

    Kumpová, I.; Vavřík, D.; Fíla, T.; Koudelka, P.; Jandejsek, I.; Jakůbek, J.; Kytýř, D.; Zlámal, P.; Vopálenský, M.; Gantar, A.

    2016-02-01

    To overcome certain limitations of contemporary materials used for bone tissue engineering, such as inflammatory response after implantation, a whole new class of materials based on polysaccharide compounds is being developed. Here, nanoparticulate bioactive glass reinforced gelan-gum (GG-BAG) has recently been proposed for the production of bone scaffolds. This material offers promising biocompatibility properties, including bioactivity and biodegradability, with the possibility of producing scaffolds with directly controlled microgeometry. However, to utilize such a scaffold with application-optimized properties, large sets of complex numerical simulations using the real microgeometry of the material have to be carried out during the development process. Because the GG-BAG is a material with intrinsically very low attenuation to X-rays, its radiographical imaging, including tomographical scanning and reconstructions, with resolution required by numerical simulations might be a very challenging task. In this paper, we present a study on X-ray imaging of GG-BAG samples. High-resolution volumetric images of investigated specimens were generated on the basis of micro-CT measurements using a large area flat-panel detector and a large area photon-counting detector. The photon-counting detector was composed of a 010× 1 matrix of Timepix edgeless silicon pixelated detectors with tiling based on overlaying rows (i.e. assembled so that no gap is present between individual rows of detectors). We compare the results from both detectors with the scanning electron microscopy on selected slices in transversal plane. It has been shown that the photon counting detector can provide approx. 3× better resolution of the details in low-attenuating materials than the integrating flat panel detectors. We demonstrate that employment of a large area photon counting detector is a good choice for imaging of low attenuating materials with the resolution sufficient for numerical simulations.

  13. Development of a single-photon-counting camera with use of a triple-stacked micro-channel plate.

    Science.gov (United States)

    Yasuda, Naruomi; Suzuki, Hitoshi; Katafuchi, Tetsuro

    2016-01-01

    At the quantum-mechanical level, all substances (not merely electromagnetic waves such as light and X-rays) exhibit wave–particle duality. Whereas students of radiation science can easily understand the wave nature of electromagnetic waves, the particle (photon) nature may elude them. Therefore, to assist students in understanding the wave–particle duality of electromagnetic waves, we have developed a photon-counting camera that captures single photons in two-dimensional images. As an image intensifier, this camera has a triple-stacked micro-channel plate (MCP) with an amplification factor of 10(6). The ultra-low light of a single photon entering the camera is first converted to an electron through the photoelectric effect on the photocathode. The electron is intensified by the triple-stacked MCP and then converted to a visible light distribution, which is measured by a high-sensitivity complementary metal oxide semiconductor image sensor. Because it detects individual photons, the photon-counting camera is expected to provide students with a complete understanding of the particle nature of electromagnetic waves. Moreover, it measures ultra-weak light that cannot be detected by ordinary low-sensitivity cameras. Therefore, it is suitable for experimental research on scintillator luminescence, biophoton detection, and similar topics.

  14. Photon counting altimeter and lidar for air and spaceborne applications

    Science.gov (United States)

    Vacek, Michael; Michalek, Vojtech; Peca, Marek; Prochazka, Ivan; Blazej, Josef; Kodet, Jan

    2011-06-01

    We are presenting the concept and preliminary design of modular multipurpose device for space segment: single photon counting laser altimeter, atmospheric lidar, laser transponder and one way laser ranging receiver. For all the mentioned purposes, the same compact configuration of the device is appropriate. Overall estimated device weight should not exceed 5 kg with the power consumption below 10 W. The device will consists of three main parts, namely, receiver, transmitter and control and processing unit. As a transmitter a commercial solid state laser at 532 nm wavelength with 10 mW power will be used. The transmitter optics will have a diameter at most of 50 mm. The laser pulse width will be of hundreds of picoseconds order. For the laser altimeter and atmospheric lidar application, the repetition rate of 10 kHz is planned in order to obtain sufficient number of data for a distance value computing. The receiver device will be composed of active quenched Single Photon Avalanche Diode module, tiny optics, and narrow-band optical filter. The core part of the control and processing unit including high precision timing unit is implemented using single FPGA chip. The preliminary device concept includes considerations on energy balance, and statistical algorithms to meet all the mentioned purposes. Recently, the bread board version of the device is under construction in our labs. The concept, construction, and timing results will be presented.

  15. A simulator for airborne laser swath mapping via photon counting

    Science.gov (United States)

    Slatton, K. C.; Carter, W. E.; Shrestha, R.

    2005-06-01

    Commercially marketed airborne laser swath mapping (ALSM) instruments currently use laser rangers with sufficient energy per pulse to work with return signals of thousands of photons per shot. The resulting high signal to noise level virtually eliminates spurious range values caused by noise, such as background solar radiation and sensor thermal noise. However, the high signal level approach requires laser repetition rates of hundreds of thousands of pulses per second to obtain contiguous coverage of the terrain at sub-meter spatial resolution, and with currently available technology, affords little scalability for significantly downsizing the hardware, or reducing the costs. A photon-counting ALSM sensor has been designed by the University of Florida and Sigma Space, Inc. for improved topographic mapping with lower power requirements and weight than traditional ALSM sensors. Major elements of the sensor design are presented along with preliminary simulation results. The simulator is being developed so that data phenomenology and target detection potential can be investigated before the system is completed. Early simulations suggest that precise estimates of terrain elevation and target detection will be possible with the sensor design.

  16. Single photon counting fluorescence lifetime detection of pericellular oxygen concentrations.

    Science.gov (United States)

    Hosny, Neveen A; Lee, David A; Knight, Martin M

    2012-01-01

    Fluorescence lifetime imaging microscopy offers a non-invasive method for quantifying local oxygen concentrations. However, existing methods are either invasive, require custom-made systems, or show limited spatial resolution. Therefore, these methods are unsuitable for investigation of pericellular oxygen concentrations. This study describes an adaptation of commercially available equipment which has been optimized for quantitative extracellular oxygen detection with high lifetime accuracy and spatial resolution while avoiding systematic photon pile-up. The oxygen sensitive fluorescent dye, tris(2,2'-bipyridyl)ruthenium(II) chloride hexahydrate [Ru(bipy)(3)](2+), was excited using a two-photon excitation laser. Lifetime was measured using a Becker & Hickl time-correlated single photon counting, which will be referred to as a TCSPC card. [Ru(bipy)(3)](2+) characterization studies quantified the influences of temperature, pH, cellular culture media and oxygen on the fluorescence lifetime measurements. This provided a precisely calibrated and accurate system for quantification of pericellular oxygen concentration based on measured lifetimes. Using this technique, quantification of oxygen concentrations around isolated viable chondrocytes, seeded in three-dimensional agarose gel, revealed a subpopulation of cells that exhibited significant spatial oxygen gradients such that oxygen concentration reduced with increasing proximity to the cell. This technique provides a powerful tool for quantifying spatial oxygen gradients within three-dimensional cellular models.

  17. Development and characterisation of a visible light photon counting imaging detector system

    CERN Document Server

    Barnstedt, J

    2002-01-01

    We report on the development of a visible light photon counting imaging detector system. The detector concept is based on standard 25 mm diameter microchannel plate image intensifiers made by Proxitronic in Bensheim (Germany). Modifications applied to these image intensifiers are the use of three microchannel plates instead of two and a high resistance ceramics plate used instead of the standard phosphor output screen. A wedge and strip anode mounted directly behind the high resistance ceramics plate was used as a read out device. This wedge and strip anode picks up the image charge of electron clouds emerging from the microchannel plates. The charge pulses are fed into four charge amplifiers and subsequently into a digital position decoding electronics, achieving a position resolution of up to 1024x1024 pixels. Mounting the anode outside the detector tube is a new approach and has the great advantage of avoiding electrical feedthroughs from the anode so that the standard image intensifier fabrication process...

  18. Ralicon anodes for image photon counting fabricated by electron beam lithography

    International Nuclear Information System (INIS)

    Burton, W.M.

    1982-01-01

    The Anger wedge and strip anode event location system developed for microchannel plate image photon detectors at the Space Sciences Laboratory of the University of California, Berkeley, has been extended in the present work by the use of electron beam lithography (EBL). This method of fabrication can be used to produce optical patterns for the subsequent manufacture of anodes by conventional photo-etching methods and has also enabled anodes to be produced directly by EBL microfabrication techniques. Computer-aided design methods have been used to develop several types of RALICON (Readout Anodes of Lithographic Construction) for use in photon counting microchannel plate imaging detectors. These anodes are suitable for linear, two dimensional or radial position measurements and they incorporate novel design features made possible by the EBL fabrication technique which significantly extend their application relative to published wedge-strip anode designs. (author)

  19. 15Mcps photon-counting X-ray computed tomography system using a ZnO-MPPC detector and its application to gadolinium imaging.

    Science.gov (United States)

    Sato, Eiichi; Sugimura, Shigeaki; Endo, Haruyuki; Oda, Yasuyuki; Abudurexiti, Abulajiang; Hagiwara, Osahiko; Osawa, Akihiro; Matsukiyo, Hiroshi; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2012-01-01

    15Mcps photon-counting X-ray computed tomography (CT) system is a first-generation type and consists of an X-ray generator, a turntable, a translation stage, a two-stage controller, a detector consisting of a 2mm-thick zinc-oxide (ZnO) single-crystal scintillator and an MPPC (multipixel photon counter) module, a counter card (CC), and a personal computer (PC). High-speed photon counting was carried out using the detector in the X-ray CT system. The maximum count rate was 15Mcps (mega counts per second) at a tube voltage of 100kV and a tube current of 1.95mA. Tomography is accomplished by repeated translations and rotations of an object, and projection curves of the object are obtained by the translation. The pulses of the event signal from the module are counted by the CC in conjunction with the PC. The minimum exposure time for obtaining a tomogram was 15min, and photon-counting CT was accomplished using gadolinium-based contrast media. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. A Near-Infrared Photon Counting Camera for High Sensitivity Astronomical Observation, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation is a Near Infrared Photon-Counting Sensor (NIRPCS), an imaging device with sufficient sensitivity to capture the spectral signatures, in the...

  1. The multichannel system of synchronous photon counting of range 50 ns - 100 ms

    Energy Technology Data Exchange (ETDEWEB)

    Dmitriev, S M [and others

    1996-12-31

    A new type of the multichannel system of synchronous photon counting is designed. The recording past of the analyzer is described and the whole measurement process is considered. Frequency of the master generator is 75 MHz. 1 ref.; 2 figs.

  2. A Near-Infrared Photon Counting Camera for High Sensitivity Astronomical Observation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation is a Near Infrared Photon-Counting Sensor (NIRPCS), an imaging device with sufficient sensitivity to capture the spectral signatures, in the...

  3. The performance of photon counting imaging with a Geiger mode silicon avalanche photodiode

    International Nuclear Information System (INIS)

    Qu, Hui-Ming; Zhang, Yi-Fan; Ji, Zhong-Jie; Chen, Qian

    2013-01-01

    In principle, photon counting imaging can detect a photon. With the development of low-level-light image intensifier techniques and low-level-light detection devices, photon counting imaging can now detect photon images under extremely low illumination. Based on a Geiger mode silicon avalanche photodiode single photon counter, an experimental system for photon counting imaging was built through two-dimensional scanning of a SPAD (single photon avalanche diode) detector. The feasibility of the imaging platform was validated experimentally. Two images with different characteristics, namely, the USAF 1951 resolution test panel and the image of Lena, were chosen to evaluate the imaging performance of the experimental system. The results were compared and analysed. The imaging properties under various illumination and scanning steps were studied. The lowest illumination limit of the SPAD photon counting imaging was determined. (letter)

  4. Coherence modulation at the photon-counting level: A new scheme for secure communication

    International Nuclear Information System (INIS)

    Rhodes, William T; Boughanmi, Abdellatif; Moreno, Yezid Torres

    2016-01-01

    When operated at the photon-counting level, coherence modulation can provide quantifiably secure binary signal transmission between two entities, security being based on the nonclonability of photons. (paper)

  5. Highly Sensitive Photon Counting Detectors for Deep Space Optical Communications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — A new type of a photon-counting photodetector is proposed to advance the state-of the-art in deep space optical communications technology. The proposed detector...

  6. Neutron radiography imaging with 2-dimensional photon counting method and its problems

    International Nuclear Information System (INIS)

    Ikeda, Y.; Kobayashi, H.; Niwa, T.; Kataoka, T.

    1988-01-01

    A ultra sensitive neutron imaging system has been deviced with a 2-dimensional photon counting camara (ARGUS 100). The imaging system is composed by a 2-dimensional single photon counting tube and a low background vidicon followed with an image processing unit and frame memories. By using the imaging system, electronic neutron radiography (NTV) has been possible under the neutron flux less than 3 x 10 4 n/cm 2 ·s. (author)

  7. Photon-counting hexagonal pixel array CdTe detector: Spatial resolution characteristics for image-guided interventional applications.

    Science.gov (United States)

    Vedantham, Srinivasan; Shrestha, Suman; Karellas, Andrew; Shi, Linxi; Gounis, Matthew J; Bellazzini, Ronaldo; Spandre, Gloria; Brez, Alessandro; Minuti, Massimo

    2016-05-01

    High-resolution, photon-counting, energy-resolved detector with fast-framing capability can facilitate simultaneous acquisition of precontrast and postcontrast images for subtraction angiography without pixel registration artifacts and can facilitate high-resolution real-time imaging during image-guided interventions. Hence, this study was conducted to determine the spatial resolution characteristics of a hexagonal pixel array photon-counting cadmium telluride (CdTe) detector. A 650 μm thick CdTe Schottky photon-counting detector capable of concurrently acquiring up to two energy-windowed images was operated in a single energy-window mode to include photons of 10 keV or higher. The detector had hexagonal pixels with apothem of 30 μm resulting in pixel pitch of 60 and 51.96 μm along the two orthogonal directions. The detector was characterized at IEC-RQA5 spectral conditions. Linear response of the detector was determined over the air kerma rate relevant to image-guided interventional procedures ranging from 1.3 nGy/frame to 91.4 μGy/frame. Presampled modulation transfer was determined using a tungsten edge test device. The edge-spread function and the finely sampled line spread function accounted for hexagonal sampling, from which the presampled modulation transfer function (MTF) was determined. Since detectors with hexagonal pixels require resampling to square pixels for distortion-free display, the optimal square pixel size was determined by minimizing the root-mean-squared-error of the aperture functions for the square and hexagonal pixels up to the Nyquist limit. At Nyquist frequencies of 8.33 and 9.62 cycles/mm along the apothem and orthogonal to the apothem directions, the modulation factors were 0.397 and 0.228, respectively. For the corresponding axis, the limiting resolution defined as 10% MTF occurred at 13.3 and 12 cycles/mm, respectively. Evaluation of the aperture functions yielded an optimal square pixel size of 54 μm. After resampling to 54

  8. Photon-counting hexagonal pixel array CdTe detector: Spatial resolution characteristics for image-guided interventional applications

    Energy Technology Data Exchange (ETDEWEB)

    Vedantham, Srinivasan; Shrestha, Suman; Karellas, Andrew, E-mail: andrew.karellas@umassmed.edu; Shi, Linxi; Gounis, Matthew J. [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 (United States); Bellazzini, Ronaldo; Spandre, Gloria; Brez, Alessandro; Minuti, Massimo [Istituto Nazionale di Fisica Nucleare (INFN), Pisa 56127, Italy and Pixirad Imaging Counters s.r.l., L. Pontecorvo 3, Pisa 56127 (Italy)

    2016-05-15

    Purpose: High-resolution, photon-counting, energy-resolved detector with fast-framing capability can facilitate simultaneous acquisition of precontrast and postcontrast images for subtraction angiography without pixel registration artifacts and can facilitate high-resolution real-time imaging during image-guided interventions. Hence, this study was conducted to determine the spatial resolution characteristics of a hexagonal pixel array photon-counting cadmium telluride (CdTe) detector. Methods: A 650 μm thick CdTe Schottky photon-counting detector capable of concurrently acquiring up to two energy-windowed images was operated in a single energy-window mode to include photons of 10 keV or higher. The detector had hexagonal pixels with apothem of 30 μm resulting in pixel pitch of 60 and 51.96 μm along the two orthogonal directions. The detector was characterized at IEC-RQA5 spectral conditions. Linear response of the detector was determined over the air kerma rate relevant to image-guided interventional procedures ranging from 1.3 nGy/frame to 91.4 μGy/frame. Presampled modulation transfer was determined using a tungsten edge test device. The edge-spread function and the finely sampled line spread function accounted for hexagonal sampling, from which the presampled modulation transfer function (MTF) was determined. Since detectors with hexagonal pixels require resampling to square pixels for distortion-free display, the optimal square pixel size was determined by minimizing the root-mean-squared-error of the aperture functions for the square and hexagonal pixels up to the Nyquist limit. Results: At Nyquist frequencies of 8.33 and 9.62 cycles/mm along the apothem and orthogonal to the apothem directions, the modulation factors were 0.397 and 0.228, respectively. For the corresponding axis, the limiting resolution defined as 10% MTF occurred at 13.3 and 12 cycles/mm, respectively. Evaluation of the aperture functions yielded an optimal square pixel size of 54

  9. A directional gamma-ray detector based on scintillator plates

    Energy Technology Data Exchange (ETDEWEB)

    Hanna, D., E-mail: hanna@physics.mcgill.ca; Sagnières, L.; Boyle, P.J.; MacLeod, A.M.L.

    2015-10-11

    A simple device for determining the azimuthal location of a source of gamma radiation, using ideas from astrophysical gamma-ray burst detection, is described. A compact and robust detector built from eight identical modules, each comprising a plate of CsI(Tl) scintillator coupled to a photomultiplier tube, can locate a point source of gamma rays with degree-scale precision by comparing the count rates in the different modules. Sensitivity to uniform environmental background is minimal.

  10. HgCdTe APD-based linear-mode photon counting components and ladar receivers

    Science.gov (United States)

    Jack, Michael; Wehner, Justin; Edwards, John; Chapman, George; Hall, Donald N. B.; Jacobson, Shane M.

    2011-05-01

    Linear mode photon counting (LMPC) provides significant advantages in comparison with Geiger Mode (GM) Photon Counting including absence of after-pulsing, nanosecond pulse to pulse temporal resolution and robust operation in the present of high density obscurants or variable reflectivity objects. For this reason Raytheon has developed and previously reported on unique linear mode photon counting components and modules based on combining advanced APDs and advanced high gain circuits. By using HgCdTe APDs we enable Poisson number preserving photon counting. A metric of photon counting technology is dark count rate and detection probability. In this paper we report on a performance breakthrough resulting from improvement in design, process and readout operation enabling >10x reduction in dark counts rate to ~10,000 cps and >104x reduction in surface dark current enabling long 10 ms integration times. Our analysis of key dark current contributors suggest that substantial further reduction in DCR to ~ 1/sec or less can be achieved by optimizing wavelength, operating voltage and temperature.

  11. Direct current stabilization of scintillation counters used for uranium prospecting

    International Nuclear Information System (INIS)

    Fraser, H.J.

    1976-01-01

    A simple system for stabilizing a scintillation counter is described which uses a dc light source (a green light emitting diode) to illuminate the photo-cathode of the photomultiplier used to detect γ-induced light pulses from the scintillator. Basically, the photomultiplier anode current due to the light emitting diode light is held constant by an automatic control loop acting on the eht voltage to keep the gain of the photomultiplier tube constant. However, because the temperature coefficient of the scintillator does not in general match that of the light emitting diode, further compensation is required to achieve constant γ pulse gain. This is provided by adding to the control circuit a current derived from the light emitting diode voltage which is an excellent measure of temperature; the use of this technique results in gain constancy to within +-1% in the 10-50 0 C ambient temperature range. Noise and countrate limitations are discussed and it is concluded that the system is generally applicable to uranium prospecting equipment. (Auth.)

  12. Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials

    Science.gov (United States)

    Nikzad, Shouleh; Hoenk, Michael; Jewell, April D.; Hennessy, John J.; Carver, Alexander G.; Jones, Todd J.; Goodsall, Timothy M.; Hamden, Erika T.; Suvarna, Puneet; Bulmer, J.; Shahedipour-Sandvik, F.; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L. Douglas

    2016-01-01

    Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100–300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness. PMID:27338399

  13. Reconfigurable Computing As an Enabling Technology for Single-Photon-Counting Laser Altimetry

    Science.gov (United States)

    Powell, Wesley; Hicks, Edward; Pinchinat, Maxime; Dabney, Philip; McGarry, Jan; Murray, Paul

    2003-01-01

    Single-photon-counting laser altimetry is a new measurement technique offering significant advantages in vertical resolution, reducing instrument size, mass, and power, and reducing laser complexity as compared to analog or threshold detection laser altimetry techniques. However, these improvements come at the cost of a dramatically increased requirement for onboard real-time data processing. Reconfigurable computing has been shown to offer considerable performance advantages in performing this processing. These advantages have been demonstrated on the Multi-KiloHertz Micro-Laser Altimeter (MMLA), an aircraft based single-photon-counting laser altimeter developed by NASA Goddard Space Flight Center with several potential spaceflight applications. This paper describes how reconfigurable computing technology was employed to perform MMLA data processing in real-time under realistic operating constraints, along with the results observed. This paper also expands on these prior results to identify concepts for using reconfigurable computing to enable spaceflight single-photon-counting laser altimeter instruments.

  14. Conversion of Beckman DK-2A spectrophotometer into an automatic single-photon counting fluorescence spectrophotometer

    International Nuclear Information System (INIS)

    Chikkur, G.C.; Lagare, M.T.; Umakantha, N.

    1981-01-01

    Details of how a DK-2A spectrophotometer can be modified into an automatic single-photon counting fluorescence spectrophotometer for recording a low intensity spectrum, are reported. The single-photon count-rate converted into a DC voltage is applied at the appropriate stage in the sample channel amplifier circuit of a DK-2A to get the pen deflection proportional to the count-rate. A high intensity spectrum may be recorded in the usual way by merely turning the shaft of the mirror motor by 180 degrees. (author)

  15. A new microcalorimeter concept for photon counting X-ray spectroscopy

    International Nuclear Information System (INIS)

    Silver, E.H.; Labov, S.E.

    1989-01-01

    We present an innovative approach for performing photon counting X-ray spectroscopy with cryogenic microcalorimeters. The detector concept takes advantage of the temperature dependence of the dielectric constant in ferroelectric materials. A dielectric calorimeter has many potential advantages over traditional resistive devices, particularly in the reduction of Johnson noise. This makes the energy resolution for photon counting spectroscopy limited only to the noise produced by the intrinsic temperature fluctuations of the device. The detector concept is presented and its predicted performance is compared with resistive calorimeters. Calculations have shown that practical instruments operating with an energy resolution less than 20 eV may be possible at 300 mK. (orig.)

  16. Universal continuous-variable quantum computation: Requirement of optical nonlinearity for photon counting

    International Nuclear Information System (INIS)

    Bartlett, Stephen D.; Sanders, Barry C.

    2002-01-01

    Although universal continuous-variable quantum computation cannot be achieved via linear optics (including squeezing), homodyne detection, and feed-forward, inclusion of ideal photon-counting measurements overcomes this obstacle. These measurements are sometimes described by arrays of beam splitters to distribute the photons across several modes. We show that such a scheme cannot be used to implement ideal photon counting and that such measurements necessarily involve nonlinear evolution. However, this requirement of nonlinearity can be moved ''off-line,'' thereby permitting universal continuous-variable quantum computation with linear optics

  17. Single Photon Counting Performance and Noise Analysis of CMOS SPAD-Based Image Sensors

    Science.gov (United States)

    Dutton, Neale A. W.; Gyongy, Istvan; Parmesan, Luca; Henderson, Robert K.

    2016-01-01

    SPAD-based solid state CMOS image sensors utilising analogue integrators have attained deep sub-electron read noise (DSERN) permitting single photon counting (SPC) imaging. A new method is proposed to determine the read noise in DSERN image sensors by evaluating the peak separation and width (PSW) of single photon peaks in a photon counting histogram (PCH). The technique is used to identify and analyse cumulative noise in analogue integrating SPC SPAD-based pixels. The DSERN of our SPAD image sensor is exploited to confirm recent multi-photon threshold quanta image sensor (QIS) theory. Finally, various single and multiple photon spatio-temporal oversampling techniques are reviewed. PMID:27447643

  18. Scintillator structures

    International Nuclear Information System (INIS)

    Cusano, D.A.; Prener, J.S.

    1978-01-01

    Distributed phosphor scintillator structures providing superior optical coupling to photoelectrically responsive devices together with methods for fabricating said scintillator structures are disclosed. In accordance with one embodiment of the invention relating to scintillator structures, the phosphor is distributed in a 'layered' fashion with certain layers being optically transparent so that the visible wavelength output of the scintillator is better directed to detecting devices. In accordance with another embodiment of the invention relating to scintillator structures, the phosphor is distributed throughout a transparent matrix in a continuous fashion whereby emitted light is more readily transmitted to a photodetector. Methods for fabricating said distributed phosphor scintillator structures are also disclosed. (Auth.)

  19. Characterization of Sphinx1 ASIC X-ray detector using photon counting and charge integration

    Science.gov (United States)

    Habib, A.; Arques, M.; Moro, J.-L.; Accensi, M.; Stanchina, S.; Dupont, B.; Rohr, P.; Sicard, G.; Tchagaspanian, M.; Verger, L.

    2018-01-01

    Sphinx1 is a novel pixel architecture adapted for X-ray imaging, it detects radiation by photon counting and charge integration. In photon counting mode, each photon is compensated by one or more counter-charges typically consisting of 100 electrons (e-) each. The number of counter-charges required gives a measure of the incoming photon energy, thus allowing spectrometric detection. Pixels can also detect radiation by integrating the charges deposited by all incoming photons during one image frame and converting this analog value into a digital response with a 100 electrons least significant bit (LSB), based on the counter-charge concept. A proof of concept test chip measuring 5 mm × 5 mm, with 200 μm × 200 μm pixels has been produced and characterized. This paper provides details on the architecture and the counter-charge design; it also describes the two modes of operation: photon counting and charge integration. The first performance measurements for this test chip are presented. Noise was found to be ~80 e-rms in photon counting mode with a power consumption of only 0.9 μW/pixel for the static analog part and 0.3 μW/pixel for the static digital part.

  20. Developments of directional detectors with NaI(Tl)/BGO scintillators

    International Nuclear Information System (INIS)

    Shirakawa, Y.

    2004-01-01

    This paper describes directional gamma ray detectors with different types of scintillators. The detectors, which positively increase directional sensitivity to incident gamma rays, have been developed to measure directions, energies and counts of gamma rays, and to search for radioactive materials such as orphan radioisotopes or contaminations. Experimental results have shown that proposed directional detectors have a potential for practical use in real fields and will contribute to radiation protection and safety

  1. TU-EF-207-02: Spectral Mammography Based on Photon Counting Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Molloi, S. [University of California (United States)

    2015-06-15

    Breast imaging technology is advancing on several fronts. In digital mammography, the major technological trend has been on optimization of approaches for performing combined mammography and tomosynthesis using the same system. In parallel, photon-counting slot-scan mammography is now in clinical use and more efforts are directed towards further development of this approach for spectral imaging. Spectral imaging refers to simultaneous acquisition of two or more energy-windowed images. Depending on the detector and associated electronics, there are a number of ways this can be accomplished. Spectral mammography using photon-counting detectors can suppress electronic noise and importantly, it enables decomposition of the image into various material compositions of interest facilitating quantitative imaging. Spectral imaging can be particularly important in intravenously injected contrast mammography and eventually tomosynthesis. The various approaches and applications of spectral mammography are discussed. Digital breast tomosynthesis relies on the mechanical movement of the x-ray tube to acquire a number of projections in a predefined arc, typically from 9 to 25 projections over a scan angle of +/−7.5 to 25 degrees depending on the particular system. The mechanical x-ray tube motion requires relatively long acquisition time, typically between 3.7 to 25 seconds depending on the system. Moreover, mechanical scanning may have an effect on the spatial resolution due to internal x-ray filament or external mechanical vibrations. New x-ray source arrays have been developed and they are aimed at replacing the scanned x-ray tube for improved acquisition time and potentially for higher spatial resolution. The potential advantages and challenges of this approach are described. Combination of digital mammography and tomosynthesis in a single system places increased demands on certain functional aspects of the detector and overall performance, particularly in the tomosynthesis

  2. TU-EF-207-02: Spectral Mammography Based on Photon Counting Detectors

    International Nuclear Information System (INIS)

    Molloi, S.

    2015-01-01

    Breast imaging technology is advancing on several fronts. In digital mammography, the major technological trend has been on optimization of approaches for performing combined mammography and tomosynthesis using the same system. In parallel, photon-counting slot-scan mammography is now in clinical use and more efforts are directed towards further development of this approach for spectral imaging. Spectral imaging refers to simultaneous acquisition of two or more energy-windowed images. Depending on the detector and associated electronics, there are a number of ways this can be accomplished. Spectral mammography using photon-counting detectors can suppress electronic noise and importantly, it enables decomposition of the image into various material compositions of interest facilitating quantitative imaging. Spectral imaging can be particularly important in intravenously injected contrast mammography and eventually tomosynthesis. The various approaches and applications of spectral mammography are discussed. Digital breast tomosynthesis relies on the mechanical movement of the x-ray tube to acquire a number of projections in a predefined arc, typically from 9 to 25 projections over a scan angle of +/−7.5 to 25 degrees depending on the particular system. The mechanical x-ray tube motion requires relatively long acquisition time, typically between 3.7 to 25 seconds depending on the system. Moreover, mechanical scanning may have an effect on the spatial resolution due to internal x-ray filament or external mechanical vibrations. New x-ray source arrays have been developed and they are aimed at replacing the scanned x-ray tube for improved acquisition time and potentially for higher spatial resolution. The potential advantages and challenges of this approach are described. Combination of digital mammography and tomosynthesis in a single system places increased demands on certain functional aspects of the detector and overall performance, particularly in the tomosynthesis

  3. Time-correlated single-photon counting study of multiple photoluminescence lifetime components of silicon nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Diamare, D., E-mail: d.diamare@ee.ucl.ac.uk [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London, WC1E 7JE (United Kingdom); Wojdak, M. [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London, WC1E 7JE (United Kingdom); Lettieri, S. [Institute for Superconductors and Innovative Materials, National Council of Research (CNR-SPIN), Via Cintia 80126, Naples (Italy); Department of Physical Sciences, University of Naples “Federico II”, Via Cintia 80126, Naples (Italy); Kenyon, A.J. [Department of Electronic and Electrical Engineering, University College London, Torrington Place, London, WC1E 7JE (United Kingdom)

    2013-04-15

    We report time-resolved photoluminescence measurements of thin films of silica containing silicon nanoclusters (Si NCs), produced by PECVD and annealed at temperatures between 700 °C and 1150 °C. While the near infrared emission of Si NCs has long been studied, visible light emission has only recently attracted interest due to its very short decay times and its recently-reported redshift with decreasing NCs size. We analyse the PL decay dynamics in the range 450–700 nm with picosecond time resolution using Time Correlated Single Photon Counting. In the resultant multi-exponential decays two dominant components can clearly be distinguished: a very short component, in the range of hundreds of picoseconds, and a nanosecond component. In this wavelength range we do not detect the microsecond component generally associated with excitonic recombination. We associate the nanosecond component to defect relaxation: it decreases in intensity in the sample annealed at higher temperature, suggesting that the contribution from defects decreases with increasing temperature. The origin of the very fast PL component (ps time region) is also discussed. We show that it is consistent with the Auger recombination times of multiple excitons. Further work needs to be done in order to assess the contribution of the Auger-controlled recombinations to the defect-assisted mechanism of photoluminescence. -- Highlights: ► We report time-resolved PL measurements of Si-Ncs embedded in SiO{sub 2} matrix. ► Net decrease of PL with increasing the annealing temperature has been observed. ► Lifetime distribution analysis revealed a multiexponential decay with ns and ps components. ► Ps components are consistent with the lifetime range of the Auger recombination times. ► No evidence for a fast direct transition at the Brillouin zone centre.

  4. Increasing the collection efficiency of time-correlated single-photon counting with single-photon avalanche diodes using immersion lenses.

    Science.gov (United States)

    Pichette, Charles; Giudice, Andrea; Thibault, Simon; Bérubé-Lauzière, Yves

    2016-11-20

    Single-photon avalanche diodes (SPADs) achieving high timing resolution (≈20-50  ps) developed for time-correlated single-photon counting (TCSPC) generally have very small photosensitive areas (25-100 μm in diameter). This limits the achievable photon counting rate and signal-to-noise ratio and may lead to long counting times. This is detrimental in applications requiring several measurements, such as fluorescence lifetime imaging (FLIM) microscopy, which requires scanning, and time-domain diffuse optical tomography (TD-DOT). We show in this work that the use of an immersion lens directly affixed onto the photosensitive area of the SPAD helps alleviate this problem by allowing more light to be concentrated onto the detector. Following careful optical design and simulations, our experimental results show that it is actually possible to achieve the predicted theoretical increase in the photon counting rate (we achieve a factor of ≈4 here). This work is of high relevance in high timing resolution TCSPC with small photosensitive area detectors and should find widespread interest in FLIM and TD-DOT with SPADs.

  5. Investigation of photon counting pixel detectors for X-ray spectroscopy and imaging

    Energy Technology Data Exchange (ETDEWEB)

    Talla, Patrick Takoukam

    2011-04-07

    The Medipix2 and Medipix3 detectors are hybrid pixelated photon counting detectors with a pixel pitch of 55 {mu}m. The sensor material used in this thesis was silicon. Because of their small pixel size they suffer from charge sharing i.e. an incoming photon can be registered by more than one pixel. In order to correct for charge sharing due to lateral diffusion of charge carriers, the Medipix3 detector was developed: with its Charge Summing Mode, the charge collected in a cluster of 2 x 2 pixel is added up and attributed to only one pixel whose counter is incremented. The adjustable threshold of the detectors allows to count the photons and to gain information on their energy. The main purposes of the thesis are to investigate spectral and imaging properties of pixelated photon counting detectors from the Medipix family such as Medipix2 and Medipix3. The investigations are based on simulations and measurements. In order to investigate the spectral properties of the detectors measurements were performed using fluorescence lines of materials such as molybdenum, silver but also some radioactive sources such as Am-241 or Cd-109. From the measured data, parameters like the threshold dispersion and the gain variation from pixel-to-pixel were extracted and used as input in the Monte Carlo code ROSI to model the responses of the detector to monoenergetic photons. The measured data are well described by the simulations for Medipix2 and for Medipix3 operating in Charge Summing Mode. Due to charge sharing and due to the energy dependence of attenuation processes in silicon and to Compton scattering the incoming and the measured spectrum differ substantially from each other. Since the responses to monoenergetic photons are known, a deconvolution was performed to determine the true incoming spectrum. Several direct and iterative methods were successfully applied on measured and simulated data of an X-ray tube and radioactive sources. The knowledge of the X-ray spectrum is

  6. Investigation of photon counting pixel detectors for X-ray spectroscopy and imaging

    International Nuclear Information System (INIS)

    Talla, Patrick Takoukam

    2011-01-01

    The Medipix2 and Medipix3 detectors are hybrid pixelated photon counting detectors with a pixel pitch of 55 μm. The sensor material used in this thesis was silicon. Because of their small pixel size they suffer from charge sharing i.e. an incoming photon can be registered by more than one pixel. In order to correct for charge sharing due to lateral diffusion of charge carriers, the Medipix3 detector was developed: with its Charge Summing Mode, the charge collected in a cluster of 2 x 2 pixel is added up and attributed to only one pixel whose counter is incremented. The adjustable threshold of the detectors allows to count the photons and to gain information on their energy. The main purposes of the thesis are to investigate spectral and imaging properties of pixelated photon counting detectors from the Medipix family such as Medipix2 and Medipix3. The investigations are based on simulations and measurements. In order to investigate the spectral properties of the detectors measurements were performed using fluorescence lines of materials such as molybdenum, silver but also some radioactive sources such as Am-241 or Cd-109. From the measured data, parameters like the threshold dispersion and the gain variation from pixel-to-pixel were extracted and used as input in the Monte Carlo code ROSI to model the responses of the detector to monoenergetic photons. The measured data are well described by the simulations for Medipix2 and for Medipix3 operating in Charge Summing Mode. Due to charge sharing and due to the energy dependence of attenuation processes in silicon and to Compton scattering the incoming and the measured spectrum differ substantially from each other. Since the responses to monoenergetic photons are known, a deconvolution was performed to determine the true incoming spectrum. Several direct and iterative methods were successfully applied on measured and simulated data of an X-ray tube and radioactive sources. The knowledge of the X-ray spectrum is

  7. Technical Note: Comparison of first- and second-generation photon-counting slit-scanning tomosynthesis systems.

    Science.gov (United States)

    Berggren, Karl; Cederström, Björn; Lundqvist, Mats; Fredenberg, Erik

    2018-02-01

    Digital breast tomosynthesis (DBT) is an emerging tool for breast-cancer screening and diagnostics. The purpose of this study is to present a second-generation photon-counting slit-scanning DBT system and compare it to the first-generation system in terms of geometry and image quality. The study presents the first image-quality measurements on the second-generation system. The geometry of the new system is based on a combined rotational and linear motion, in contrast to a purely rotational scan motion in the first generation. In addition, the calibration routines have been updated. Image quality was measured in the center of the image field in terms of in-slice modulation transfer function (MTF), artifact spread function (ASF), and in-slice detective quantum efficiency (DQE). Images were acquired using a W/Al 29 kVp spectrum at 13 mAs with 2 mm Al additional filtration and reconstructed using simple back-projection. The in-slice 50% MTF was improved in the chest-mammilla direction, going from 3.2 to 3.5 lp/mm, and the zero-frequency DQE increased from 0.71 to 0.77. The MTF and ASF were otherwise found to be on par for the two systems. The new system has reduced in-slice variation of the tomographic angle. The new geometry is less curved, which reduces in-slice tomographic-angle variation, and increases the maximum compression height, making the system accessible for a larger population. The improvements in MTF and DQE were attributed to the updated calibration procedures. We conclude that the second-generation system maintains the key features of the photon-counting system while maintaining or improving image quality and improving the maximum compression height. © 2017 American Association of Physicists in Medicine.

  8. Photon Counting System for High-Sensitivity Detection of Bioluminescence at Optical Fiber End.

    Science.gov (United States)

    Iinuma, Masataka; Kadoya, Yutaka; Kuroda, Akio

    2016-01-01

    The technique of photon counting is widely used for various fields and also applicable to a high-sensitivity detection of luminescence. Thanks to recent development of single photon detectors with avalanche photodiodes (APDs), the photon counting system with an optical fiber has become powerful for a detection of bioluminescence at an optical fiber end, because it allows us to fully use the merits of compactness, simple operation, highly quantum efficiency of the APD detectors. This optical fiber-based system also has a possibility of improving the sensitivity to a local detection of Adenosine triphosphate (ATP) by high-sensitivity detection of the bioluminescence. In this chapter, we are introducing a basic concept of the optical fiber-based system and explaining how to construct and use this system.

  9. Photon-counting digital radiography using high-pressure xenon filled detectors

    CERN Document Server

    Li, Maozhen; Johns, P C

    2001-01-01

    Digital radiography overcomes many of the limitations of the traditional screen/film system. Further enhancements in the digital radiography image are possible if the X-ray image receptor could measure the energy of individual photons instead of simply integrating their energy, as is the case at present. A prototype photon counting scanned projection radiography system has been constructed, which combines a Gas Electron Multiplier (GEM) and a Gas Microstrip Detector (GMD) using Xe : CH sub 4 (90 : 10) at high pressure. With the gain contribution from the GEM, the GMD can be operated at lower and safer voltages making the imaging system more reliable. Good energy resolution, and spatial resolution comparable to that of screen/film, have been demonstrated for the GEM/GMD hybrid imaging system in photon counting mode for X-ray spectra up to 50 kV.

  10. A high-throughput, multi-channel photon-counting detector with picosecond timing

    CERN Document Server

    Lapington, J S; Miller, G M; Ashton, T J R; Jarron, P; Despeisse, M; Powolny, F; Howorth, J; Milnes, J

    2009-01-01

    High-throughput photon counting with high time resolution is a niche application area where vacuum tubes can still outperform solid-state devices. Applications in the life sciences utilizing time-resolved spectroscopies, particularly in the growing field of proteomics, will benefit greatly from performance enhancements in event timing and detector throughput. The HiContent project is a collaboration between the University of Leicester Space Research Centre, the Microelectronics Group at CERN, Photek Ltd., and end-users at the Gray Cancer Institute and the University of Manchester. The goal is to develop a detector system specifically designed for optical proteomics, capable of high content (multi-parametric) analysis at high throughput. The HiContent detector system is being developed to exploit this niche market. It combines multi-channel, high time resolution photon counting in a single miniaturized detector system with integrated electronics. The combination of enabling technologies; small pore microchanne...

  11. Ultrafast time measurements by time-correlated single photon counting coupled with superconducting single photon detector

    Energy Technology Data Exchange (ETDEWEB)

    Shcheslavskiy, V., E-mail: vis@becker-hickl.de; Becker, W. [Becker & Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin (Germany); Morozov, P.; Divochiy, A. [Scontel, Rossolimo St., 5/22-1, Moscow 119021 (Russian Federation); Vakhtomin, Yu. [Scontel, Rossolimo St., 5/22-1, Moscow 119021 (Russian Federation); Moscow State Pedagogical University, 1/1 M. Pirogovskaya St., Moscow 119991 (Russian Federation); Smirnov, K. [Scontel, Rossolimo St., 5/22-1, Moscow 119021 (Russian Federation); Moscow State Pedagogical University, 1/1 M. Pirogovskaya St., Moscow 119991 (Russian Federation); National Research University Higher School of Economics, 20 Myasnitskaya St., Moscow 101000 (Russian Federation)

    2016-05-15

    Time resolution is one of the main characteristics of the single photon detectors besides quantum efficiency and dark count rate. We demonstrate here an ultrafast time-correlated single photon counting (TCSPC) setup consisting of a newly developed single photon counting board SPC-150NX and a superconducting NbN single photon detector with a sensitive area of 7 × 7 μm. The combination delivers a record instrument response function with a full width at half maximum of 17.8 ps and system quantum efficiency ∼15% at wavelength of 1560 nm. A calculation of the root mean square value of the timing jitter for channels with counts more than 1% of the peak value yielded about 7.6 ps. The setup has also good timing stability of the detector–TCSPC board.

  12. Spectroscopic micro-tomography of metallic-organic composites by means of photon-counting detectors

    Czech Academy of Sciences Publication Activity Database

    Pichotka, Martin; Jakůbek, Jan; Vavřík, Daniel

    2015-01-01

    Roč. 10, č. 12 (2015), C12033 ISSN 1748-0221 R&D Projects: GA MŠk(CZ) LO1219 Keywords : micro-tomography * photon-counting detectors * metallic-organic composites Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.310, year: 2015 http://iopscience.iop.org/article/10.1088/1748-0221/10/12/C12033/pdf

  13. Modeling the frequency-dependent detective quantum efficiency of photon-counting x-ray detectors.

    Science.gov (United States)

    Stierstorfer, Karl

    2018-01-01

    To find a simple model for the frequency-dependent detective quantum efficiency (DQE) of photon-counting detectors in the low flux limit. Formula for the spatial cross-talk, the noise power spectrum and the DQE of a photon-counting detector working at a given threshold are derived. Parameters are probabilities for types of events like single counts in the central pixel, double counts in the central pixel and a neighboring pixel or single count in a neighboring pixel only. These probabilities can be derived in a simple model by extensive use of Monte Carlo techniques: The Monte Carlo x-ray propagation program MOCASSIM is used to simulate the energy deposition from the x-rays in the detector material. A simple charge cloud model using Gaussian clouds of fixed width is used for the propagation of the electric charge generated by the primary interactions. Both stages are combined in a Monte Carlo simulation randomizing the location of impact which finally produces the required probabilities. The parameters of the charge cloud model are fitted to the spectral response to a polychromatic spectrum measured with our prototype detector. Based on the Monte Carlo model, the DQE of photon-counting detectors as a function of spatial frequency is calculated for various pixel sizes, photon energies, and thresholds. The frequency-dependent DQE of a photon-counting detector in the low flux limit can be described with an equation containing only a small set of probabilities as input. Estimates for the probabilities can be derived from a simple model of the detector physics. © 2017 American Association of Physicists in Medicine.

  14. Controversy among giants: Young's experiment and loss of fringe visibility at low photon-count levels

    Science.gov (United States)

    Rhodes, William T.

    2011-09-01

    An ideal beam splitter model for an absorber presented by Leonhardt in his book Measuring the Quantum State of Light (Cambridge University Press, 1997) has intriguing implications for the simple Young's fringe experiment in the photon-counting regime. Specifically, it suggests that different results will be obtained depending on whether the light forming the fringes is attenuated at the source or at the slits.

  15. A multispectral photon-counting double random phase encoding scheme for image authentication.

    Science.gov (United States)

    Yi, Faliu; Moon, Inkyu; Lee, Yeon H

    2014-05-20

    In this paper, we propose a new method for color image-based authentication that combines multispectral photon-counting imaging (MPCI) and double random phase encoding (DRPE) schemes. The sparsely distributed information from MPCI and the stationary white noise signal from DRPE make intruder attacks difficult. In this authentication method, the original multispectral RGB color image is down-sampled into a Bayer image. The three types of color samples (red, green and blue color) in the Bayer image are encrypted with DRPE and the amplitude part of the resulting image is photon counted. The corresponding phase information that has nonzero amplitude after photon counting is then kept for decryption. Experimental results show that the retrieved images from the proposed method do not visually resemble their original counterparts. Nevertheless, the original color image can be efficiently verified with statistical nonlinear correlations. Our experimental results also show that different interpolation algorithms applied to Bayer images result in different verification effects for multispectral RGB color images.

  16. Update on Linear Mode Photon Counting with the HgCdTe Linear Mode Avalanche Photodiode

    Science.gov (United States)

    Beck, Jeffrey D.; Kinch, Mike; Sun, Xiaoli

    2014-01-01

    The behavior of the gain-voltage characteristic of the mid-wavelength infrared cutoff HgCdTe linear mode avalanche photodiode (e-APD) is discussed both experimentally and theoretically as a function of the width of the multiplication region. Data are shown that demonstrate a strong dependence of the gain at a given bias voltage on the width of the n- gain region. Geometrical and fundamental theoretical models are examined to explain this behavior. The geometrical model takes into account the gain-dependent optical fill factor of the cylindrical APD. The theoretical model is based on the ballistic ionization model being developed for the HgCdTe APD. It is concluded that the fundamental theoretical explanation is the dominant effect. A model is developed that combines both the geometrical and fundamental effects. The model also takes into account the effect of the varying multiplication width in the low bias region of the gain-voltage curve. It is concluded that the lower than expected gain seen in the first 2 × 8 HgCdTe linear mode photon counting APD arrays, and higher excess noise factor, was very likely due to the larger than typical multiplication region length in the photon counting APD pixel design. The implications of these effects on device photon counting performance are discussed.

  17. A Multispectral Photon-Counting Double Random Phase Encoding Scheme for Image Authentication

    Directory of Open Access Journals (Sweden)

    Faliu Yi

    2014-05-01

    Full Text Available In this paper, we propose a new method for color image-based authentication that combines multispectral photon-counting imaging (MPCI and double random phase encoding (DRPE schemes. The sparsely distributed information from MPCI and the stationary white noise signal from DRPE make intruder attacks difficult. In this authentication method, the original multispectral RGB color image is down-sampled into a Bayer image. The three types of color samples (red, green and blue color in the Bayer image are encrypted with DRPE and the amplitude part of the resulting image is photon counted. The corresponding phase information that has nonzero amplitude after photon counting is then kept for decryption. Experimental results show that the retrieved images from the proposed method do not visually resemble their original counterparts. Nevertheless, the original color image can be efficiently verified with statistical nonlinear correlations. Our experimental results also show that different interpolation algorithms applied to Bayer images result in different verification effects for multispectral RGB color images.

  18. Development of new photon-counting detectors for single-molecule fluorescence microscopy

    Science.gov (United States)

    Michalet, X.; Colyer, R. A.; Scalia, G.; Ingargiola, A.; Lin, R.; Millaud, J. E.; Weiss, S.; Siegmund, Oswald H. W.; Tremsin, Anton S.; Vallerga, John V.; Cheng, A.; Levi, M.; Aharoni, D.; Arisaka, K.; Villa, F.; Guerrieri, F.; Panzeri, F.; Rech, I.; Gulinatti, A.; Zappa, F.; Ghioni, M.; Cova, S.

    2013-01-01

    Two optical configurations are commonly used in single-molecule fluorescence microscopy: point-like excitation and detection to study freely diffusing molecules, and wide field illumination and detection to study surface immobilized or slowly diffusing molecules. Both approaches have common features, but also differ in significant aspects. In particular, they use different detectors, which share some requirements but also have major technical differences. Currently, two types of detectors best fulfil the needs of each approach: single-photon-counting avalanche diodes (SPADs) for point-like detection, and electron-multiplying charge-coupled devices (EMCCDs) for wide field detection. However, there is room for improvements in both cases. The first configuration suffers from low throughput owing to the analysis of data from a single location. The second, on the other hand, is limited to relatively low frame rates and loses the benefit of single-photon-counting approaches. During the past few years, new developments in point-like and wide field detectors have started addressing some of these issues. Here, we describe our recent progresses towards increasing the throughput of single-molecule fluorescence spectroscopy in solution using parallel arrays of SPADs. We also discuss our development of large area photon-counting cameras achieving subnanosecond resolution for fluorescence lifetime imaging applications at the single-molecule level. PMID:23267185

  19. New approach to the dosimetry of ionizing radiations by fluorescence measurement, according to the single photon counting technique, correlated in time at the nanosecond scale

    International Nuclear Information System (INIS)

    Sohier, Till

    2011-01-01

    This research thesis reports the first fundamental study of the dosimetry of charged and gamma radiations by measurement of fluorescence resolved in time at a nanosecond scale, in organic matter. This method allows an in-depth and real-time analysis of the deposited dose, while taking ionisation as well as excitation processes into account. The author describes mechanisms of interaction and deposition of energy on dense matter, reports the detailed study of the ion-matter interaction, and the interaction of secondary electrons produced within traces. He addresses mechanisms of energy relaxation, and more particularly the study or organic scintillators. Then, he presents the adopted experimental approach: experimental observation with a statistic reconstitution of the curve representing the intensity of the emitted fluorescence in time and with a nanosecond resolution by using a scintillating sensor for time correlated single photon counting (TCSPC). The next part reports the development of an experimental multi-modal platform for dosimetry by TCSPC aimed at the measurement of fluorescence decays under pulsed excitation (nanosecond pulsed ion beams) and continuous flow excitation (non pulsed beams and radioactive sources). Experimental results are then presented for fluorescence measurements, and compared with measurements obtained by using an ionization chamber under the same irradiation conditions: dose deposited by hellions and carbon ions within polyvinyl toluene and polyethylene terephthalate, use of scintillating optic fibers under gamma irradiation of Caesium 137 and Cobalt 60. A new experimental approach is finally presented to perform dosimetry measurements while experimentally ignoring luminescence produced by Cerenkov effect [fr

  20. Quantitative spectral K-edge imaging in preclinical photon-counting x-ray computed tomography.

    Science.gov (United States)

    de Vries, Anke; Roessl, Ewald; Kneepkens, Esther; Thran, Axel; Brendel, Bernhard; Martens, Gerhard; Proska, Roland; Nicolay, Klaas; Grüll, Holger

    2015-04-01

    The objective of this study was to investigate the feasibility and the accuracy of spectral computed tomography (spectral CT) to determine the tissue concentrations and localization of high-attenuation, iodine-based contrast agents in mice. Iodine tissue concentrations determined with spectral CT are compared with concentrations measured with single-photon emission computed tomography (SPECT) and inductively coupled plasma mass spectrometry (ICP-MS). All animal procedures were performed according to the US National Institutes of Health principles of laboratory animal care and were approved by the ethical review committee of Maastricht, The Netherlands. Healthy Swiss mice (n = 4) were injected with an iodinated emulsion radiolabeled with indium as multimodal contrast agent for CT and SPECT. The CT and SPECT scans were acquired using a dedicated small-animal SPECT/CT system. Subsequently, scans were performed with a preclinical spectral CT scanner equipped with a photon-counting detector and 6 energy threshold levels. Quantitative data analysis of SPECT and spectral CT scans were obtained using 3-dimensional volumes-of-interest drawing methods. The ICP-MS on dissected organs was performed to determine iodine uptake per organ and was compared with the amounts determined from spectral CT and SPECT. Iodine concentrations obtained with image-processed spectral CT data correlated well with data obtained either with noninvasive SPECT imaging (slope = 0.96, r = 0.75) or with ICP-MS (slope = 0.99, r = 0.89) in tissue samples. This preclinical proof-of-concept study shows the in vivo quantification of iodine concentrations in tissues using spectral CT. Our multimodal imaging approach with spectral CT and SPECT using radiolabeled iodinated emulsions together with ICP-based quantification allows a direct comparison of all methods. Benchmarked against ICP-MS data, spectral CT in the present implementation shows a slight underestimation of organ iodine concentrations compared

  1. High-Sensitivity Semiconductor Photocathodes for Space-Born UV Photon-Counting and Imaging, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Many UV photon-counting and imaging applications, including space-borne astronomy, missile tracking and guidance, UV spectroscopy for chemical/biological...

  2. Optimization of a photon rejecter to separate electronic noise in a photon-counting detector

    International Nuclear Information System (INIS)

    Cho, Hyo-Min; Choi, Yu-Na; Lee, Seung-Wan; Lee, Young-Jin; Ryu, Hyun-Ju; Kim, Hee-Joung

    2012-01-01

    Photon-counting-based X-ray imaging technology provides the capability to count individual photons and to characterize photon energies. The cadmium telluride (CdTe)-based photon-counting detector is limited in capability, however, under a high X-ray flux. A photon rejecter composed of aluminum, for example, can reduce this limitation by modulating the incident number of photons. In addition to this function, the optimal photon rejecter can separate electronic noise, which degrades image quality. The aim of this work was to optimize a photon rejecter for high-quality image acquisition by removing electronic noise from the actual pulse signal. The images and spectra were acquired using a micro-focus X-ray source with a CdTe-based photon-counting detector. We acquired data with various types of photon-rejecter materials composed of aluminum (Al) and iodine at three different tube voltages (50, 70, and 90 kVp). A phantom composed of high-atomic-number materials was imaged to evaluate the efficiency of the photon rejecter. Photon rejecters composed of 1-mm Al, 10-mm Al, and a combination of 10-mm Al and iodine provided optimum capability at 50, 70, and 90 kVp, respectively. Each optimal combination of photon-rejecter material and voltage effectively separated electronic noise from the actual pulse signal and gave the highest contrast-to-noise ratio for materials on the image. These optimized types of photon rejecters can effectively discriminate electronic noise and improve image quality at different tube voltages.

  3. A Burst-Mode Photon-Counting Receiver with Automatic Channel Estimation and Bit Rate Detection

    Science.gov (United States)

    2016-02-24

    Grein, M.E., Elgin, L.E., Robinson, B.S., Kachelmyer, A.L., Caplan , D.O., Stevens, M.L., Carney, J.J., Hamilton, S.A., and Boroson, D.M., “Demonstration...Robinson, B.S., Kerman, A.J., Dauler, E.A., Barron, R.J., Caplan , D.O., Stevens, M.L., Carney, J.J., Hamilton, S.A., Yang, J.K.W., and Berggren, K.K., “781...Mbit/s photon-counting optical communications using a superconducting nanowire detector,” Optics Letters, v. 31 no. 4 444-446 (2006). [14] Caplan

  4. Macintosh/LabVIEW based control and data acquisition system for a single photon counting fluorometer

    Science.gov (United States)

    Stryjewski, Wieslaw J.

    1991-08-01

    A flexible software system has been developed for controlling fluorescence decay measurements using the virtual instrument approach offered by LabVIEW. The time-correlated single photon counting instrument operates under computer control in both manual and automatic mode. Implementation time was short and the equipment is now easier to use, reducing the training time required for new investigators. It is not difficult to customize the front panel or adapt the program to a different instrument. We found LabVIEW much more convenient to use for this application than traditional, textual computer languages.

  5. Single-photon counting in the 1550-nm wavelength region for quantum cryptography

    International Nuclear Information System (INIS)

    Park, Chul-Woo; Park, Jun-Bum; Park, Young-Soo; Lee, Seung-Hun; Shin, Hyun-Jun; Bae, Byung-Seong; Moon, Sung; Han, Sang-Kook

    2006-01-01

    In this paper, we report the measured performance of an InGaAs avalanche photodiode (APD) Module fabricated for single-photon counting. We measured the dark current noise, the after-pulse noise, and the quantum efficiency of the single- photon detector for different temperatures. We then examined our single-photon source and detection system by measuring the coincident probability. From our measurement, we observed that the after-pulse effect of the APD at temperatures below 105 .deg. C caused cascade noise build-up on the succeeding electrical signals.

  6. Imaging of small children with a prototype for photon counting tomosynthesis

    Science.gov (United States)

    del Risco Norrlid, Lilián; Fredenberg, Erik; Hemmendorff, Magnus; Jackowski, Christian; Danielsson, Mats

    2009-02-01

    We present data on a first prototype for photon counting tomosynthesis imaging of small children, which we call photoncounting tomosynthesis (PCT). A photon counting detector can completely eliminate electronic noise, which makes it ideal for tomosynthesis because of the low dose in each projection. Another advantage is that the detector allows for energy sensitivity in later versions, which will further lower the radiation dose. In-plane resolution is high and has been measured to be 5 lp/mm, at least 4 times better than in CT, while the depth resolution was significantly lower than typical CT resolution. The image SNR decreased from 30 to 10 for a detail of 10 mm depth in increasing thickness of PMMA from 10 to 80 mm. The air kerma measured for PCT was 5.2 mGy, which leads to an organ dose to the brain of approximately 0.7 mGy. This dose is 96 % lower than a typical CT dose. PCT can be appealing for pediatric imaging since young children have an increased sensitivity to radiation induced cancers. We have acquired post mortem images of a newborn with the new device and with a state-of-the-art CT and compared the diagnostic information and dose levels of the two modalities. The results are promising but more work is needed to provide input to a next generation prototype that would be suitable for clinical trials.

  7. The Dosepix detector—an energy-resolving photon-counting pixel detector for spectrometric measurements

    CERN Document Server

    Zang, A; Ballabriga, R; Bisello, F; Campbell, M; Celi, J C; Fauler, A; Fiederle, M; Jensch, M; Kochanski, N; Llopart, X; Michel, N; Mollenhauer, U; Ritter, I; Tennert, F; Wölfel, S; Wong, W; Michel, T

    2015-01-01

    The Dosepix detector is a hybrid photon-counting pixel detector based on ideas of the Medipix and Timepix detector family. 1 mm thick cadmium telluride and 300 μm thick silicon were used as sensor material. The pixel matrix of the Dosepix consists of 16 x 16 square pixels with 12 rows of (200 μm)2 and 4 rows of (55 μm)2 sensitive area for the silicon sensor layer and 16 rows of pixels with 220 μm pixel pitch for CdTe. Besides digital energy integration and photon-counting mode, a novel concept of energy binning is included in the pixel electronics, allowing energy-resolved measurements in 16 energy bins within one acquisition. The possibilities of this detector concept range from applications in personal dosimetry and energy-resolved imaging to quality assurance of medical X-ray sources by analysis of the emitted photon spectrum. In this contribution the Dosepix detector, its response to X-rays as well as spectrum measurements with Si and CdTe sensor layer are presented. Furthermore, a first evaluation wa...

  8. Photon-counting 1.0 GHz-phase-modulation fluorometer

    Energy Technology Data Exchange (ETDEWEB)

    Mizuno, T.; Nakao, S.; Mizutani, Y.; Iwata, T., E-mail: iwata@tokushima-u.ac.jp [Division of Energy System, Institute of Technology and Science, Tokushima University, 2-1 Minami-Jyosanjima, Tokushima 770-8506 (Japan)

    2015-04-15

    We have constructed an improved version of a photon-counting phase-modulation fluorometer (PC-PMF) with a maximum modulation frequency of 1.0 GHz, where a phase domain measurement is conducted with a time-correlated single-photon-counting electronics. While the basic concept of the PC-PMF has been reported previously by one of the authors, little attention has been paid to its significance, other than its weak fluorescence measurement capability. Recently, we have recognized the importance of the PC-PMF and its potential for fluorescence lifetime measurements. One important aspect of the PC-PMF is that it enables us to perform high-speed measurements that exceed the frequency bandwidths of the photomultiplier tubes that are commonly used as fluorescence detectors. We describe the advantages of the PC-PMF and demonstrate its usefulness based on fundamental performance tests. In our new version of the PC-PMF, we have used a laser diode (LD) as an excitation light source rather than the light-emitting diode that was used in the primary version. We have also designed a simple and stable LD driver to modulate the device. Additionally, we have obtained a sinusoidal histogram waveform that has multiple cycles within a time span to be measured, which is indispensable for precise phase measurements. With focus on the fluorescence intensity and the resolution time, we have compared the performance of the PC-PMF with that of a conventional PMF using the analogue light detection method.

  9. Fast imaging by photon counting application to long-baseline optical stellar interferometry

    International Nuclear Information System (INIS)

    Morel, Sebastien

    1998-01-01

    Image acquisition by photon counting in the visible spectrum with a high precision on photo-events dating is especially useful for ground-based observations. In the first part of this thesis, and after a review of several techniques for photon acquisition and processing, I introduce a new type of photon counting camera, noticeable for its high temporal resolution and its high maximum counting rate: the DELTA (Detector Enhancement by Linear-projections on Three Axes) camera. I describe the concept of this camera, and the engineering solutions (optics, electronics, computing) that could be used for its construction. The second part of my work regards fringe detection and tracking in ground-based and long- baseline optical stellar interferometry. After a statistical approach of the issue, I describe methods introducing a priori information in the data, in order to have a better detection efficiency. One of the proposed methods, using a priori information on the atmospheric piston, requires a precise photo-event dating, and therefore uses methods described in the first part. (author) [fr

  10. Polarimetric, Two-Color, Photon-Counting Laser Altimeter Measurements of Forest Canopy Structure

    Science.gov (United States)

    Harding, David J.; Dabney, Philip W.; Valett, Susan

    2011-01-01

    Laser altimeter measurements of forest stands with distinct structures and compositions have been acquired at 532 nm (green) and 1064 nm (near-infrared) wavelengths and parallel and perpendicular polarization states using the Slope Imaging Multi-polarization Photon Counting Lidar (SIMPL). The micropulse, single photon ranging measurement approach employed by SIMPL provides canopy structure measurements with high vertical and spatial resolution. Using a height distribution analysis method adapted from conventional, 1064 nm, full-waveform lidar remote sensing, the sensitivity of two parameters commonly used for above-ground biomass estimation are compared as a function of wavelength. The results for the height of median energy (HOME) and canopy cover are for the most part very similar, indicating biomass estimations using lidars operating at green and near-infrared wavelengths will yield comparable estimates. The expected detection of increasing depolarization with depth into the canopies due to volume multiple-scattering was not observed, possibly due to the small laser footprint and the small detector field of view used in the SIMPL instrument. The results of this work provide pathfinder information for NASA's ICESat-2 mission that will employ a 532 nm, micropulse, photon counting laser altimeter.

  11. The Slope Imaging Multi-Polarization Photon-Counting Lidar: Development and Performance Results

    Science.gov (United States)

    Dabney, Phillip

    2010-01-01

    The Slope Imaging Multi-polarization Photon-counting Lidar is an airborne instrument developed to demonstrate laser altimetry measurement methods that will enable more efficient observations of topography and surface properties from space. The instrument was developed through the NASA Earth Science Technology Office Instrument Incubator Program with a focus on cryosphere remote sensing. The SIMPL transmitter is an 11 KHz, 1064 nm, plane-polarized micropulse laser transmitter that is frequency doubled to 532 nm and split into four push-broom beams. The receiver employs single-photon, polarimetric ranging at 532 and 1064 nm using Single Photon Counting Modules in order to achieve simultaneous sampling of surface elevation, slope, roughness and depolarizing scattering properties, the latter used to differentiate surface types. Data acquired over ice-covered Lake Erie in February, 2009 are documenting SIMPL s measurement performance and capabilities, demonstrating differentiation of open water and several ice cover types. ICESat-2 will employ several of the technologies advanced by SIMPL, including micropulse, single photon ranging in a multi-beam, push-broom configuration operating at 532 nm.

  12. Range walk error correction and modeling on Pseudo-random photon counting system

    Science.gov (United States)

    Shen, Shanshan; Chen, Qian; He, Weiji

    2017-08-01

    Signal to noise ratio and depth accuracy are modeled for the pseudo-random ranging system with two random processes. The theoretical results, developed herein, capture the effects of code length and signal energy fluctuation are shown to agree with Monte Carlo simulation measurements. First, the SNR is developed as a function of the code length. Using Geiger-mode avalanche photodiodes (GMAPDs), longer code length is proven to reduce the noise effect and improve SNR. Second, the Cramer-Rao lower bound on range accuracy is derived to justify that longer code length can bring better range accuracy. Combined with the SNR model and CRLB model, it is manifested that the range accuracy can be improved by increasing the code length to reduce the noise-induced error. Third, the Cramer-Rao lower bound on range accuracy is shown to converge to the previously published theories and introduce the Gauss range walk model to range accuracy. Experimental tests also converge to the presented boundary model in this paper. It has been proven that depth error caused by the fluctuation of the number of detected photon counts in the laser echo pulse leads to the depth drift of Time Point Spread Function (TPSF). Finally, numerical fitting function is used to determine the relationship between the depth error and the photon counting ratio. Depth error due to different echo energy is calibrated so that the corrected depth accuracy is improved to 1cm.

  13. Photon-counting 1.0 GHz-phase-modulation fluorometer

    International Nuclear Information System (INIS)

    Mizuno, T.; Nakao, S.; Mizutani, Y.; Iwata, T.

    2015-01-01

    We have constructed an improved version of a photon-counting phase-modulation fluorometer (PC-PMF) with a maximum modulation frequency of 1.0 GHz, where a phase domain measurement is conducted with a time-correlated single-photon-counting electronics. While the basic concept of the PC-PMF has been reported previously by one of the authors, little attention has been paid to its significance, other than its weak fluorescence measurement capability. Recently, we have recognized the importance of the PC-PMF and its potential for fluorescence lifetime measurements. One important aspect of the PC-PMF is that it enables us to perform high-speed measurements that exceed the frequency bandwidths of the photomultiplier tubes that are commonly used as fluorescence detectors. We describe the advantages of the PC-PMF and demonstrate its usefulness based on fundamental performance tests. In our new version of the PC-PMF, we have used a laser diode (LD) as an excitation light source rather than the light-emitting diode that was used in the primary version. We have also designed a simple and stable LD driver to modulate the device. Additionally, we have obtained a sinusoidal histogram waveform that has multiple cycles within a time span to be measured, which is indispensable for precise phase measurements. With focus on the fluorescence intensity and the resolution time, we have compared the performance of the PC-PMF with that of a conventional PMF using the analogue light detection method

  14. Dual-contrast agent photon-counting computed tomography of the heart: initial experience.

    Science.gov (United States)

    Symons, Rolf; Cork, Tyler E; Lakshmanan, Manu N; Evers, Robert; Davies-Venn, Cynthia; Rice, Kelly A; Thomas, Marvin L; Liu, Chia-Ying; Kappler, Steffen; Ulzheimer, Stefan; Sandfort, Veit; Bluemke, David A; Pourmorteza, Amir

    2017-08-01

    To determine the feasibility of dual-contrast agent imaging of the heart using photon-counting detector (PCD) computed tomography (CT) to simultaneously assess both first-pass and late enhancement of the myocardium. An occlusion-reperfusion canine model of myocardial infarction was used. Gadolinium-based contrast was injected 10 min prior to PCD CT. Iodinated contrast was infused immediately prior to PCD CT, thus capturing late gadolinium enhancement as well as first-pass iodine enhancement. Gadolinium and iodine maps were calculated using a linear material decomposition technique and compared to single-energy (conventional) images. PCD images were compared to in vivo and ex vivo magnetic resonance imaging (MRI) and histology. For infarct versus remote myocardium, contrast-to-noise ratio (CNR) was maximal on late enhancement gadolinium maps (CNR 9.0 ± 0.8, 6.6 ± 0.7, and 0.4 ± 0.4, p contrast agent cardiac imaging is feasible with photon-counting detector CT. These initial proof-of-concept results may provide incentives to develop new k-edge contrast agents, to investigate possible interactions between multiple simultaneously administered contrast agents, and to ultimately bring them to clinical practice.

  15. Photon counting microstrip X-ray detectors with GaAs sensors

    Science.gov (United States)

    Ruat, M.; Andrä, M.; Bergamaschi, A.; Barten, R.; Brückner, M.; Dinapoli, R.; Fröjdh, E.; Greiffenberg, D.; Lopez-Cuenca, C.; Lozinskaya, A. D.; Mezza, D.; Mozzanica, A.; Novikov, V. A.; Ramilli, M.; Redford, S.; Ruder, C.; Schmitt, B.; Shi, X.; Thattil, D.; Tinti, G.; Tolbanov, O. P.; Tyazhev, A.; Vetter, S.; Zarubin, A. N.; Zhang, J.

    2018-01-01

    High-Z sensors are increasingly used to overcome the poor efficiency of Si sensors above 15 keV, and further extend the energy range of synchrotron and FEL experiments. Detector-grade GaAs sensors of 500 μm thickness offer 98% absorption efficiency at 30 keV and 50% at 50 keV . In this work we assess the usability of GaAs sensors in combination with the MYTHEN photon-counting microstrip readout chip developed at PSI. Different strip length and pitch are compared, and the detector performance is evaluated in regard of the sensor material properties. Despite increased leakage current and noise, photon-counting strips mounted with GaAs sensors can be used with photons of energy as low as 5 keV, and exhibit excellent linearity with energy. The charge sharing is doubled as compared to silicon strips, due to the high diffusion coefficient of electrons in GaAs.

  16. Analysis of the factors that affect photon counts in Compton scattering

    International Nuclear Information System (INIS)

    Luo, Guang; Xiao, Guangyu

    2015-01-01

    Compton scattering has been applied in a variety of fields. The factors that affect Compton scattering have been studied extensively in the literature. However, the factors that affect the measured photon counts in Compton scattering are rarely considered. In this paper, we make a detailed discussion on those factors. First, Compton scattering experiments of some alloy series and powder mixture series are explored. Second, the electron density is researched in terms of atom and lattice constants. Third, the factor of attenuation coefficient is discussed. And then, the active degree of electrons is discussed based on the DFT theory. Lastly, the conclusions are made, that the factors affecting Compton scattering photon counts include mainly electron number density, attenuation coefficient and active degree of electrons. - Highlights: • Compton scattering experiments of some alloy series and powder mixture series are explored. • The influence of electron density is researched in terms of atom and lattice constants. • The influence of attenuation coefficient is discussed. • The active degree of electrons is discussed detailedly based on DFT theory

  17. Detector Motion Method to Increase Spatial Resolution in Photon-Counting Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Daehee; Park, Kyeongjin; Lim, Kyung Taek; Cho, Gyuseong [Korea Advanced Institute of Science and Technology, Daejon (Korea, Republic of)

    2017-03-15

    Medical imaging requires high spatial resolution of an image to identify fine lesions. Photoncounting detectors in medical imaging have recently been rapidly replacing energy-integrating detectors due to the former's high spatial resolution, high efficiency and low noise. Spatial resolution in a photon counting image is determined by the pixel size. Therefore, the smaller the pixel size, the higher the spatial resolution that can be obtained in an image. However, detector redesigning is required to reduce pixel size, and an expensive fine process is required to integrate a signal processing unit with reduced pixel size. Furthermore, as the pixel size decreases, charge sharing severely deteriorates spatial resolution. To increase spatial resolution, we propose a detector motion method using a large pixel detector that is less affected by charge sharing. To verify the proposed method, we utilized a UNO-XRI photon-counting detector (1-mm CdTe, Timepix chip) at the maximum X-ray tube voltage of 80 kVp. A similar spatial resolution of a 55-μm-pixel image was achieved by application of the proposed method to a 110-μm-pixel detector with a higher signal-to-noise ratio. The proposed method could be a way to increase spatial resolution without a pixel redesign when pixels severely suffer from charge sharing as pixel size is reduced.

  18. A study of pile-up in integrated time-correlated single photon counting systems.

    Science.gov (United States)

    Arlt, Jochen; Tyndall, David; Rae, Bruce R; Li, David D-U; Richardson, Justin A; Henderson, Robert K

    2013-10-01

    Recent demonstration of highly integrated, solid-state, time-correlated single photon counting (TCSPC) systems in CMOS technology is set to provide significant increases in performance over existing bulky, expensive hardware. Arrays of single photon single photon avalanche diode (SPAD) detectors, timing channels, and signal processing can be integrated on a single silicon chip with a degree of parallelism and computational speed that is unattainable by discrete photomultiplier tube and photon counting card solutions. New multi-channel, multi-detector TCSPC sensor architectures with greatly enhanced throughput due to minimal detector transit (dead) time or timing channel dead time are now feasible. In this paper, we study the potential for future integrated, solid-state TCSPC sensors to exceed the photon pile-up limit through analytic formula and simulation. The results are validated using a 10% fill factor SPAD array and an 8-channel, 52 ps resolution time-to-digital conversion architecture with embedded lifetime estimation. It is demonstrated that pile-up insensitive acquisition is attainable at greater than 10 times the pulse repetition rate providing over 60 dB of extended dynamic range to the TCSPC technique. Our results predict future CMOS TCSPC sensors capable of live-cell transient observations in confocal scanning microscopy, improved resolution of near-infrared optical tomography systems, and fluorescence lifetime activated cell sorting.

  19. The effect of event shape on centroiding in photon counting detectors

    International Nuclear Information System (INIS)

    Kawakami, Hajime; Bone, David; Fordham, John; Michel, Raul

    1994-01-01

    High resolution, CCD readout, photon counting detectors employ simple centroiding algorithms for defining the spatial position of each detected event. The accuracy of centroiding is very dependent upon a number of parameters including the profile, energy and width of the intensified event. In this paper, we provide an analysis of how the characteristics of an intensified event change as the input count rate increases and the consequent effect on centroiding. The changes in these parameters are applied in particular to the MIC photon counting detector developed at UCL for ground and space based astronomical applications. This detector has a maximum format of 3072x2304 pixels permitting its use in the highest resolution applications. Individual events, at light level from 5 to 1000k events/s over the detector area, were analysed. It was found that both the asymmetry and width of event profiles were strongly dependent upon the energy of the intensified event. The variation in profile then affected the centroiding accuracy leading to loss of resolution. These inaccuracies have been quantified for two different 3 CCD pixel centroiding algorithms and one 2 pixel algorithm. The results show that a maximum error of less than 0.05 CCD pixel occurs with the 3 pixel algorithms and 0.1 CCD pixel for the 2 pixel algorithm. An improvement is proposed by utilising straight pore MCPs in the intensifier and a 70 μm air gap in front of the CCD. ((orig.))

  20. WE-FG-207A-04: Performance Characteristics of Photon-Counting Breast CT

    Energy Technology Data Exchange (ETDEWEB)

    Kalender, W. [University of Erlangen (Germany)

    2016-06-15

    investigating dedicated breast CT. The development of large-area flat-panel detectors with field-of-view sufficient to image the entire breast in each projection enabled development of flat-panel cone-beam breast CT. More recently, the availability of complimentary metal-oxide semiconductor (CMOS) detectors with lower system noise and finer pixel pitch, combined with the development of x-ray tubes with focal spot dimensions similar to mammography systems, has shown improved spatial resolution and could improve visualization of microcalcifications. These technological developments promise clinical translation of low-dose cone-beam breast CT. Dedicated photon-counting breast CT (pcBCT) systems represent a novel detector design, which provide high spatial resolution (∼ 100µm) and low mean glandular dose (MGD). The CdTe-based direct conversion detector technology was previously evaluated and confirmed by simulations and basic experiments on laboratory setups [Kalender et al., Eur Radiol 22: 1–8, 2012]. Measurements of dose, technical image quality parameters, and surgical specimens on a pcBCT scanner have been completed. Comparative evaluation of surgical specimens showed that pcBCT outperformed mammography and digital breast tomosynthesis with respect to 3D spatial resolution, detectability of calcifications, and soft tissue delineation. Major barriers to widespread clinical use of BCT relate to radiation dose, imaging of microcalcifications, and adequate coverage of breast tissue near the chest wall. Adequate chest wall coverage is also technically challenging but recent progress in x-ray tube, detector and table design now enables full breast coverage in the majority of patients. At this time, BCT has been deemed to be suitable for diagnostic imaging but not yet for screening. The mean glandular dose (MGD) from BCT has been reported to be between 5.7 to 27.8 mGy, and this range is comparable to, and within the range of, the MGD of 2.6 to 31.6 mGy in diagnostic mammography

  1. A directional fast neutron detector using scintillating fibers and an intensified CCD camera system

    International Nuclear Information System (INIS)

    Holslin, Daniel; Armstrong, A.W.; Hagan, William; Shreve, David; Smith, Scott

    1994-01-01

    We have been developing and testing a scintillating fiber detector (SFD) for use as a fast neutron sensor which can discriminate against neutrons entering at angles non-parallel to the fiber axis (''directionality''). The detector/convertor component is a fiber bundle constructed of plastic scintillating fibers each measuring 10 cm long and either 0.3 mm or 0.5 mm in diameter. Extensive Monte Carlo simulations were made to optimize the bundle response to a range of fast neutron energies and to intense fluxes of high energy gamma-rays. The bundle is coupled to a set of gamma-ray insenitive electro-optic intensifiers whose output is viewed by a CCD camera directly coupled to the intensifiers. Two types of CCD cameras were utilized: 1) a standard, interline RS-170 camera with electronic shuttering and 2) a high-speed (up to 850 frame/s) field-transfer camera. Measurements of the neutron detection efficiency and directionality were made using 14 MeV neutrons, and the response to gamma-rays was performed using intense fluxes from radioisotopic sources (up to 20 R/h). Recently, the detector was constructed and tested using a large 10 cm by 10 cm square fiber bundle coupled to a 10 cm diameter GEN I intensifier tube. We present a description of the various detector systems and report the results of experimental tests. ((orig.))

  2. Photon Counting Energy Dispersive Detector Arrays for X-ray Imaging.

    Science.gov (United States)

    Iwanczyk, Jan S; Nygård, Einar; Meirav, Oded; Arenson, Jerry; Barber, William C; Hartsough, Neal E; Malakhov, Nail; Wessel, Jan C

    2009-01-01

    The development of an innovative detector technology for photon-counting in X-ray imaging is reported. This new generation of detectors, based on pixellated cadmium telluride (CdTe) and cadmium zinc telluride (CZT) detector arrays electrically connected to application specific integrated circuits (ASICs) for readout, will produce fast and highly efficient photon-counting and energy-dispersive X-ray imaging. There are a number of applications that can greatly benefit from these novel imagers including mammography, planar radiography, and computed tomography (CT). Systems based on this new detector technology can provide compositional analysis of tissue through spectroscopic X-ray imaging, significantly improve overall image quality, and may significantly reduce X-ray dose to the patient. A very high X-ray flux is utilized in many of these applications. For example, CT scanners can produce ~100 Mphotons/mm(2)/s in the unattenuated beam. High flux is required in order to collect sufficient photon statistics in the measurement of the transmitted flux (attenuated beam) during the very short time frame of a CT scan. This high count rate combined with a need for high detection efficiency requires the development of detector structures that can provide a response signal much faster than the transit time of carriers over the whole detector thickness. We have developed CdTe and CZT detector array structures which are 3 mm thick with 16×16 pixels and a 1 mm pixel pitch. These structures, in the two different implementations presented here, utilize either a small pixel effect or a drift phenomenon. An energy resolution of 4.75% at 122 keV has been obtained with a 30 ns peaking time using discrete electronics and a (57)Co source. An output rate of 6×10(6) counts per second per individual pixel has been obtained with our ASIC readout electronics and a clinical CT X-ray tube. Additionally, the first clinical CT images, taken with several of our prototype photon-counting and

  3. Sensitivity of photon-counting based K-edge imaging in X-ray computed tomography.

    Science.gov (United States)

    Roessl, Ewald; Brendel, Bernhard; Engel, Klaus-Jürgen; Schlomka, Jens-Peter; Thran, Axel; Proksa, Roland

    2011-09-01

    The feasibility of K-edge imaging using energy-resolved, photon-counting transmission measurements in X-ray computed tomography (CT) has been demonstrated by simulations and experiments. The method is based on probing the discontinuities of the attenuation coefficient of heavy elements above and below the K-edge energy by using energy-sensitive, photon counting X-ray detectors. In this paper, we investigate the dependence of the sensitivity of K-edge imaging on the atomic number Z of the contrast material, on the object diameter D , on the spectral response of the X-ray detector and on the X-ray tube voltage. We assume a photon-counting detector equipped with six adjustable energy thresholds. Physical effects leading to a degradation of the energy resolution of the detector are taken into account using the concept of a spectral response function R(E,U) for which we assume four different models. As a validation of our analytical considerations and in order to investigate the influence of elliptically shaped phantoms, we provide CT simulations of an anthropomorphic Forbild-Abdomen phantom containing a gold-contrast agent. The dependence on the values of the energy thresholds is taken into account by optimizing the achievable signal-to-noise ratios (SNR) with respect to the threshold values. We find that for a given X-ray spectrum and object size the SNR in the heavy element's basis material image peaks for a certain atomic number Z. The dependence of the SNR in the high- Z basis-material image on the object diameter is the natural, exponential decrease with particularly deteriorating effects in the case where the attenuation from the object itself causes a total signal loss below the K-edge. The influence of the energy-response of the detector is very important. We observed that the optimal SNR values obtained with an ideal detector and with a CdTe pixel detector whose response, showing significant tailing, has been determined at a synchrotron differ by factors of

  4. Photon-counting-based diffraction phase microscopy combined with single-pixel imaging

    Science.gov (United States)

    Shibuya, Kyuki; Araki, Hiroyuki; Iwata, Tetsuo

    2018-04-01

    We propose a photon-counting (PC)-based quantitative-phase imaging (QPI) method for use in diffraction phase microscopy (DPM) that is combined with a single-pixel imaging (SPI) scheme (PC-SPI-DPM). This combination of DPM with the SPI scheme overcomes a low optical throughput problem that has occasionally prevented us from obtaining quantitative-phase images in DPM through use of a high-sensitivity single-channel photodetector such as a photomultiplier tube (PMT). The introduction of a PMT allowed us to perform PC with ease and thus solved a dynamic range problem that was inherent to SPI. As a proof-of-principle experiment, we performed a comparison study of analogue-based SPI-DPM and PC-SPI-DPM for a 125-nm-thick indium tin oxide (ITO) layer coated on a silica glass substrate. We discuss the basic performance of the method and potential future modifications of the proposed system.

  5. Characterization of spectrometric photon-counting X-ray detectors at different pitches

    Science.gov (United States)

    Jurdit, M.; Brambilla, A.; Moulin, V.; Ouvrier-Buffet, P.; Radisson, P.; Verger, L.

    2017-09-01

    There is growing interest in energy-sensitive photon-counting detectors based on high flux X-ray imaging. Their potential applications include medical imaging, non-destructive testing and security. Innovative detectors of this type will need to count individual photons and sort them into selected energy bins, at several million counts per second and per mm2. Cd(Zn)Te detector grade materials with a thickness of 1.5 to 3 mm and pitches from 800 μm down to 200 μm were assembled onto interposer boards. These devices were tested using in-house-developed full-digital fast readout electronics. The 16-channel demonstrators, with 256 energy bins, were experimentally characterized by determining spectral resolution, count rate, and charge sharing, which becomes challenging at low pitch. Charge sharing correction was found to efficiently correct X-ray spectra up to 40 × 106 incident photons.s-1.mm-2.

  6. Gating circuit for single photon-counting fluorescence lifetime instruments using high repetition pulsed light sources

    International Nuclear Information System (INIS)

    Laws, W.R.; Potter, D.W.; Sutherland, J.C.

    1984-01-01

    We have constructed a circuit that permits conventional timing electronics to be used in single photon-counting fluorimeters with high repetition rate excitation sources (synchrotrons and mode-locked lasers). Most commercial time-to-amplitude and time-to-digital converters introduce errors when processing very short time intervals and when subjected to high-frequency signals. This circuit reduces the frequency of signals representing the pulsed light source (stops) to the rate of detected fluorescence events (starts). Precise timing between the start/stop pair is accomplished by using the second stop pulse after a start pulse. Important features of our design are that the circuit is insensitive to the simultaneous occurrence of start and stop signals and that the reduction in the stop frequency allows the start/stop time interval to be placed in linear regions of the response functions of commercial timing electronics

  7. Linear Mode HgCdTe Avalanche Photodiodes for Photon Counting Applications

    Science.gov (United States)

    Sullivan, William, III; Beck, Jeffrey; Scritchfield, Richard; Skokan, Mark; Mitra, Pradip; Sun, Xiaoli; Abshire, James; Carpenter, Darren; Lane, Barry

    2015-01-01

    An overview of recent improvements in the understanding and maturity of linear mode photon counting with HgCdTe electron-initiated avalanche photodiodes is presented. The first HgCdTe LMPC 2x8 format array fabricated in 2011 with 64 micron pitch was a remarkable success in terms of demonstrating a high single photon signal to noise ratio of 13.7 with an excess noise factor of 1.3-1.4, a 7 ns minimum time between events, and a broad spectral response extending from 0.4 micron to 4.2 micron. The main limitations were a greater than 10x higher false event rate than expected of greater than 1 MHz, a 5-7x lower than expected APD gain, and a photon detection efficiency of only 50% when greater than 60% was expected. This paper discusses the reasons behind these limitations and the implementation of their mitigations with new results.

  8. High energy X-ray photon counting imaging using linear accelerator and silicon strip detectors

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Y., E-mail: cycjty@sophie.q.t.u-tokyo.ac.jp [Department of Bioengineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Shimazoe, K.; Yan, X. [Department of Nuclear Engineering and Management, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Ueda, O.; Ishikura, T. [Fuji Electric Co., Ltd., Fuji, Hino, Tokyo 191-8502 (Japan); Fujiwara, T. [National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Uesaka, M.; Ohno, M. [Nuclear Professional School, the University of Tokyo, 2-22 Shirakata-shirane, Tokai, Ibaraki 319-1188 (Japan); Tomita, H. [Department of Quantum Engineering, Nagoya University, Furo, Chikusa, Nagoya 464-8603 (Japan); Yoshihara, Y. [Department of Nuclear Engineering and Management, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Takahashi, H. [Department of Bioengineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Nuclear Engineering and Management, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2016-09-11

    A photon counting imaging detector system for high energy X-rays is developed for on-site non-destructive testing of thick objects. One-dimensional silicon strip (1 mm pitch) detectors are stacked to form a two-dimensional edge-on module. Each detector is connected to a 48-channel application specific integrated circuit (ASIC). The threshold-triggered events are recorded by a field programmable gate array based counter in each channel. The detector prototype is tested using 950 kV linear accelerator X-rays. The fast CR shaper (300 ns pulse width) of the ASIC makes it possible to deal with the high instant count rate during the 2 μs beam pulse. The preliminary imaging results of several metal and concrete samples are demonstrated.

  9. High energy X-ray photon counting imaging using linear accelerator and silicon strip detectors

    International Nuclear Information System (INIS)

    Tian, Y.; Shimazoe, K.; Yan, X.; Ueda, O.; Ishikura, T.; Fujiwara, T.; Uesaka, M.; Ohno, M.; Tomita, H.; Yoshihara, Y.; Takahashi, H.

    2016-01-01

    A photon counting imaging detector system for high energy X-rays is developed for on-site non-destructive testing of thick objects. One-dimensional silicon strip (1 mm pitch) detectors are stacked to form a two-dimensional edge-on module. Each detector is connected to a 48-channel application specific integrated circuit (ASIC). The threshold-triggered events are recorded by a field programmable gate array based counter in each channel. The detector prototype is tested using 950 kV linear accelerator X-rays. The fast CR shaper (300 ns pulse width) of the ASIC makes it possible to deal with the high instant count rate during the 2 μs beam pulse. The preliminary imaging results of several metal and concrete samples are demonstrated.

  10. Mu-Spec - A High Performance Ultra-Compact Photon Counting spectrometer for Space Submillimeter Astronomy

    Science.gov (United States)

    Moseley, H.; Hsieh, W.-T.; Stevenson, T.; Wollack, E.; Brown, A.; Benford, D.; Sadleir; U-Yen, I.; Ehsan, N.; Zmuidzinas, J.; hide

    2011-01-01

    We have designed and are testing elements of a fully integrated submillimeter spectrometer based on superconducting microstrip technology. The instrument can offer resolving power R approximately 1500, and its high frequency cutoff is set by the gap of available high performance superconductors. All functions of the spectrometer are integrated - light is coupled to the microstrip circuit with a planar antenna, the spectra discrimination is achieved using a synthetic grating, orders are separated using planar filter, and detected using photon counting MKID detector. This spectrometer promises to revolutionize submillimeter spectroscopy from space. It replaces instruments with the scale of 1m with a spectrometer on a 10 cm Si wafer. The reduction in mass and volume promises a much higher performance system within available resource in a space mission. We will describe the system and the performance of the components that have been fabricated and tested.

  11. X-ray imaging with photon counting hybrid semiconductor pixel detectors

    CERN Document Server

    Manolopoulos, S; Campbell, M; Snoeys, W; Heijne, Erik H M; Pernigotti, E; Raine, C; Smith, K; Watt, J; O'Shea, V; Ludwig, J; Schwarz, C

    1999-01-01

    Semiconductor pixel detectors, originally developed for particle physics experiments, have been studied as X-ray imaging devices. The performance of devices using the OMEGA 3 read-out chip bump-bonded to pixellated silicon semiconductor detectors is characterised in terms of their signal-to-noise ratio when exposed to 60 kVp X-rays. Although parts of the devices achieve values of this ratio compatible with the noise being photon statistics limited, this is not found to hold for the whole pixel matrix, resulting in the global signal-to-noise ratio being compromised. First results are presented of X-ray images taken with a gallium arsenide pixel detector bump-bonded to a new read-out chip, (MEDIPIX), which is a single photon counting read-out chip incorporating a 15-bit counter in every pixel. (author)

  12. Performance and capacity analysis of Poisson photon-counting based Iter-PIC OCDMA systems.

    Science.gov (United States)

    Li, Lingbin; Zhou, Xiaolin; Zhang, Rong; Zhang, Dingchen; Hanzo, Lajos

    2013-11-04

    In this paper, an iterative parallel interference cancellation (Iter-PIC) technique is developed for optical code-division multiple-access (OCDMA) systems relying on shot-noise limited Poisson photon-counting reception. The novel semi-analytical tool of extrinsic information transfer (EXIT) charts is used for analysing both the bit error rate (BER) performance as well as the channel capacity of these systems and the results are verified by Monte Carlo simulations. The proposed Iter-PIC OCDMA system is capable of achieving two orders of magnitude BER improvements and a 0.1 nats of capacity improvement over the conventional chip-level OCDMA systems at a coding rate of 1/10.

  13. Irradiation of the CLARO-CMOS chip, a fast ASIC for single-photon counting

    International Nuclear Information System (INIS)

    Andreotti, M.; Baldini, W.; Calabrese, R.; Carniti, P.; Cassina, L.; Cotta Ramusino, A.; Fiorini, M.; Giachero, A.; Gotti, C.; Luppi, E.; Maino, M.; Malaguti, R.; Pessina, G.; Tomassetti, L.

    2015-01-01

    The CLARO-CMOS is a prototype ASIC that allows fast photon counting with low power consumption, built in AMS 0.35 μm CMOS technology. It is intended to be used as a front-end readout for the upgraded LHCb RICH detectors. In this environment, assuming 10 years of operation at the nominal luminosity expected after the upgrade, the ASIC must withstand a total fluence of about 6×10 12 1 MeV n eq /cm 2 and a total ionising dose of 400 krad. Long term stability of the electronics front-end is essential and the effects of radiation damage on the CLARO-CMOS performance must be carefully studied. This paper describes results of multi-step irradiation tests with protons up to the dose of ~8 Mrad, including measurement of single event effects during irradiation and chip performance evaluation before and after each irradiation step

  14. Photon counting imaging and centroiding with an electron-bombarded CCD using single molecule localisation software

    International Nuclear Information System (INIS)

    Hirvonen, Liisa M.; Barber, Matthew J.; Suhling, Klaus

    2016-01-01

    Photon event centroiding in photon counting imaging and single-molecule localisation in super-resolution fluorescence microscopy share many traits. Although photon event centroiding has traditionally been performed with simple single-iteration algorithms, we recently reported that iterative fitting algorithms originally developed for single-molecule localisation fluorescence microscopy work very well when applied to centroiding photon events imaged with an MCP-intensified CMOS camera. Here, we have applied these algorithms for centroiding of photon events from an electron-bombarded CCD (EBCCD). We find that centroiding algorithms based on iterative fitting of the photon events yield excellent results and allow fitting of overlapping photon events, a feature not reported before and an important aspect to facilitate an increased count rate and shorter acquisition times.

  15. Radiation-Resistant Photon-Counting Detector Package Providing Sub-ps Stability for Laser Time Transfer in Space

    Science.gov (United States)

    Prochzaka, Ivan; Kodat, Jan; Blazej, Josef; Sun, Xiaoli (Editor)

    2015-01-01

    We are reporting on a design, construction and performance of photon-counting detector packages based on silicon avalanche photodiodes. These photon-counting devices have been optimized for extremely high stability of their detection delay. The detectors have been designed for future applications in fundamental metrology and optical time transfer in space. The detectors have been qualified for operation in space missions. The exceptional radiation tolerance of the detection chip itself and of all critical components of a detector package has been verified in a series of experiments.

  16. Evaluation of a hybrid photon counting pixel detector for X-ray polarimetry

    International Nuclear Information System (INIS)

    Michel, T.; Durst, J.

    2008-01-01

    It has already been shown in literature that X-ray sensitive CCDs can be used to measure the degree of linear polarization of X-rays using the effect that photoelectrons are emitted with a non-isotropic angular distribution in respect to the orientation of the electric field vector of impinging photons. Up to now hybrid semiconductor pixel detectors like the Timepix-detector have never been used for X-ray polarimetry. The main reason for this is that the pixel pitch is large compared to CCDs which results in a much smaller analyzing power. On the other hand, the active thickness of the sensor layer can be larger than in CCDs leading to an increased efficiency. Therefore hybrid photon counting pixel detectors may be used for imaging and polarimetry at higher photon energies. For irradiation with polarized X-ray photons we were able to measure an asymmetry between vertical and horizontal double hit events in neighboring pixels of the hybrid photon counting Timepix-detector at room temperature. For the specific spectrum used in our experiment an average polarization asymmetry of (0.96±0.02)% was measured. Additionally, the Timepix-detector with its spectroscopic time-over-threshold-mode was used to measure the dependence of the polarization asymmetry on energy deposition in the detector. Polarization asymmetries between 0.2% at 29 keV and 3.4% at 78 keV energy deposition were determined. The results can be reproduced with our EGS4-based Monte-Carlo simulation

  17. A high-throughput, multi-channel photon-counting detector with picosecond timing

    Science.gov (United States)

    Lapington, J. S.; Fraser, G. W.; Miller, G. M.; Ashton, T. J. R.; Jarron, P.; Despeisse, M.; Powolny, F.; Howorth, J.; Milnes, J.

    2009-06-01

    High-throughput photon counting with high time resolution is a niche application area where vacuum tubes can still outperform solid-state devices. Applications in the life sciences utilizing time-resolved spectroscopies, particularly in the growing field of proteomics, will benefit greatly from performance enhancements in event timing and detector throughput. The HiContent project is a collaboration between the University of Leicester Space Research Centre, the Microelectronics Group at CERN, Photek Ltd., and end-users at the Gray Cancer Institute and the University of Manchester. The goal is to develop a detector system specifically designed for optical proteomics, capable of high content (multi-parametric) analysis at high throughput. The HiContent detector system is being developed to exploit this niche market. It combines multi-channel, high time resolution photon counting in a single miniaturized detector system with integrated electronics. The combination of enabling technologies; small pore microchannel plate devices with very high time resolution, and high-speed multi-channel ASIC electronics developed for the LHC at CERN, provides the necessary building blocks for a high-throughput detector system with up to 1024 parallel counting channels and 20 ps time resolution. We describe the detector and electronic design, discuss the current status of the HiContent project and present the results from a 64-channel prototype system. In the absence of an operational detector, we present measurements of the electronics performance using a pulse generator to simulate detector events. Event timing results from the NINO high-speed front-end ASIC captured using a fast digital oscilloscope are compared with data taken with the proposed electronic configuration which uses the multi-channel HPTDC timing ASIC.

  18. A high-throughput, multi-channel photon-counting detector with picosecond timing

    International Nuclear Information System (INIS)

    Lapington, J.S.; Fraser, G.W.; Miller, G.M.; Ashton, T.J.R.; Jarron, P.; Despeisse, M.; Powolny, F.; Howorth, J.; Milnes, J.

    2009-01-01

    High-throughput photon counting with high time resolution is a niche application area where vacuum tubes can still outperform solid-state devices. Applications in the life sciences utilizing time-resolved spectroscopies, particularly in the growing field of proteomics, will benefit greatly from performance enhancements in event timing and detector throughput. The HiContent project is a collaboration between the University of Leicester Space Research Centre, the Microelectronics Group at CERN, Photek Ltd., and end-users at the Gray Cancer Institute and the University of Manchester. The goal is to develop a detector system specifically designed for optical proteomics, capable of high content (multi-parametric) analysis at high throughput. The HiContent detector system is being developed to exploit this niche market. It combines multi-channel, high time resolution photon counting in a single miniaturized detector system with integrated electronics. The combination of enabling technologies; small pore microchannel plate devices with very high time resolution, and high-speed multi-channel ASIC electronics developed for the LHC at CERN, provides the necessary building blocks for a high-throughput detector system with up to 1024 parallel counting channels and 20 ps time resolution. We describe the detector and electronic design, discuss the current status of the HiContent project and present the results from a 64-channel prototype system. In the absence of an operational detector, we present measurements of the electronics performance using a pulse generator to simulate detector events. Event timing results from the NINO high-speed front-end ASIC captured using a fast digital oscilloscope are compared with data taken with the proposed electronic configuration which uses the multi-channel HPTDC timing ASIC.

  19. A burst-mode photon counting receiver with automatic channel estimation and bit rate detection

    Science.gov (United States)

    Rao, Hemonth G.; DeVoe, Catherine E.; Fletcher, Andrew S.; Gaschits, Igor D.; Hakimi, Farhad; Hamilton, Scott A.; Hardy, Nicholas D.; Ingwersen, John G.; Kaminsky, Richard D.; Moores, John D.; Scheinbart, Marvin S.; Yarnall, Timothy M.

    2016-04-01

    We demonstrate a multi-rate burst-mode photon-counting receiver for undersea communication at data rates up to 10.416 Mb/s over a 30-foot water channel. To the best of our knowledge, this is the first demonstration of burst-mode photon-counting communication. With added attenuation, the maximum link loss is 97.1 dB at λ=517 nm. In clear ocean water, this equates to link distances up to 148 meters. For λ=470 nm, the achievable link distance in clear ocean water is 450 meters. The receiver incorporates soft-decision forward error correction (FEC) based on a product code of an inner LDPC code and an outer BCH code. The FEC supports multiple code rates to achieve error-free performance. We have selected a burst-mode receiver architecture to provide robust performance with respect to unpredictable channel obstructions. The receiver is capable of on-the-fly data rate detection and adapts to changing levels of signal and background light. The receiver updates its phase alignment and channel estimates every 1.6 ms, allowing for rapid changes in water quality as well as motion between transmitter and receiver. We demonstrate on-the-fly rate detection, channel BER within 0.2 dB of theory across all data rates, and error-free performance within 1.82 dB of soft-decision capacity across all tested code rates. All signal processing is done in FPGAs and runs continuously in real time.

  20. An optimized method for the reconstruction of the direction of air showers for scintillator arrays

    Energy Technology Data Exchange (ETDEWEB)

    Krawczynski, H.; Prahl, J.; Arqueros, F.; Bradbury, S.; Cortina, J.; Deckers, T.; Eckmann, R.; Feigl, E.; Fernandez, J.; Fonseca, V.; Funk, B.; Gebauer, J.; Gonzalez, J.C.; Haustein, V.; Heinzelmann, G.; Holl, I.; Kirstein, O.; Kornmeyer, H.; Krennrich, F.; Lindner, A.; Lorenz, E.; Magnussen, N.; Martinez, S.; Merck, M.; Meyer, H.; Mirzoyan, R.; Moeller, H.; Moralejo, A.; Mueller, N.; Padilla, L.; Petry, D.; Plaga, R.; Prosch, C.; Rauterberg, G.; Rhode, W.; Samorski, M.; Sanchez, J.A.; Schmele, D.; Sooth, R.N.; Stamm, W.; Westerhoff, S.; Wiebel-Sooth, B.; Willmer, M. [Hamburg Univ. (Germany). 2. Inst. fuer Experimentalphys.]|[Universidad Complutense, Facultad de Ciencias Fisicas, Ciudad Universitaria, E-28040 Madrid (Spain)]|[Max Planck Institut fuer Physik, Foehringer Ring 6, D-80805 Muenchen (Germany)]|[Universitaet Kiel, Institut fuer Kernphysik, Olshausenstr. 40, D-24118 Kiel (Germany)]|[Universitaet Wuppertal, Fachbereich Physik, Gaussstr.20, D-42097 Wuppertal (Germany)

    1996-12-11

    An optimized method is presented for the reconstruction of air shower directions for scintillator arrays. The method takes into account that both the expectation value and the spread of the measured arrival times not only depend on the distance of a counter from the shower axis, but also on the number of particles registered in that counter. It also takes into account that the distributions of the measured arrival times are not Gaussian. For showers recorded with the HEGRA scintillator array above the threshold energy of E{sub thres}= 20 TeV the mean angular resolution obtained with this method is left angle {sigma}{sup {theta}}{sub 63%} right angle =1.0 {sup circle}, and above a threshold E{sub thres}= 50 TeV it is left angle {sigma}{sup {theta}}{sub 63%} right angle =0.6 {sup circle}. Comparing the new procedure with the HEGRA standard procedure the angular resolution has improved on average by a factor of 1.33. The mis-pointing has been determined with an accuracy of 0.15 {sup circle}. The method is developed using experimental data. (orig.).

  1. Clinical dosimetry with plastic scintillators - Almost energy independent, direct absorbed dose reading with high resolution

    Energy Technology Data Exchange (ETDEWEB)

    Quast, U; Fluehs, D [Department of Radiotherapy, Essen (Germany). Div. of Clinical Radiation Physics; Fluehs, D; Kolanoski, H [Dortmund Univ. (Germany). Inst. fuer Physik

    1996-08-01

    Clinical dosimetry is still far behind the goal to measure any spatial or temporal distribution of absorbed dose fast and precise without disturbing the physical situation by the dosimetry procedure. NE 102A plastic scintillators overcome this border. These tissue substituting dosemeter probes open a wide range of new clinical applications of dosimetry. This versatile new dosimetry system enables fast measurement of the absorbed dose to water in water also in regions with a steep dose gradient, close to interfaces, or in partly shielded regions. It allows direct reading dosimetry in the energy range of all clinically used external photon and electron beams, or around all branchytherapy sources. Thin detector arrays permit fast and high resolution measurements in quality assurance, such as in-vivo dosimetry or even afterloading dose monitoring. A main field of application is the dosimetric treatment planning, the individual optimization of brachytherapy applicators. Thus, plastic scintillator dosemeters cover optimally all difficult fields of clinical dosimetry. An overview about its characteristics and applications is given here. 20 refs, 1 fig.

  2. An optimized method for the reconstruction of the direction of air showers for scintillator arrays

    International Nuclear Information System (INIS)

    Krawczynski, H.; Prahl, J.; Arqueros, F.; Bradbury, S.; Cortina, J.; Deckers, T.; Eckmann, R.; Feigl, E.; Fernandez, J.; Fonseca, V.; Funk, B.; Gebauer, J.; Gonzalez, J.C.; Haustein, V.; Heinzelmann, G.; Holl, I.; Kirstein, O.; Kornmeyer, H.; Krennrich, F.; Lindner, A.; Lorenz, E.; Magnussen, N.; Martinez, S.; Merck, M.; Meyer, H.; Mirzoyan, R.; Moeller, H.; Moralejo, A.; Mueller, N.; Padilla, L.; Petry, D.; Plaga, R.; Prosch, C.; Rauterberg, G.; Rhode, W.; Samorski, M.; Sanchez, J.A.; Schmele, D.; Sooth, R.N.; Stamm, W.; Westerhoff, S.; Wiebel-Sooth, B.; Willmer, M.

    1996-01-01

    An optimized method is presented for the reconstruction of air shower directions for scintillator arrays. The method takes into account that both the expectation value and the spread of the measured arrival times not only depend on the distance of a counter from the shower axis, but also on the number of particles registered in that counter. It also takes into account that the distributions of the measured arrival times are not Gaussian. For showers recorded with the HEGRA scintillator array above the threshold energy of E thres = 20 TeV the mean angular resolution obtained with this method is left angle σ θ 63% right angle =1.0 circle , and above a threshold E thres = 50 TeV it is left angle σ θ 63% right angle =0.6 circle . Comparing the new procedure with the HEGRA standard procedure the angular resolution has improved on average by a factor of 1.33. The mis-pointing has been determined with an accuracy of 0.15 circle . The method is developed using experimental data. (orig.)

  3. A direct measurement of the invisible width of the Z from single photon counting

    Science.gov (United States)

    Buskulic, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Minard, M.-N.; Pietrzyk, B.; Ariztizabal, F.; Comas, P.; Crespo, J. M.; Delfino, M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Gaitan, V.; Garrido, Ll.; Mattison, T.; Pacheco, A.; Padilla, C.; Pasual, A.; Creanza, D.; de Palma, M.; Farilla, A.; Iaselli, G.; Maggi, G.; Natali, S.; Nuzzo, S.; Quattromini, M.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Chai, Y.; Hu, H.; Huang, D.; Huang, X.; Lin, J.; Wang, T.; Xie, Y.; Xu, D.; Xu, R.; Zhang, J.; Zhang, L.; Zhao, W.; Blucher, E.; Bonvicini, G.; Boudreau, J.; Casper, D.; Drevermann, H.; Forty, R. W.; Ganis, G.; Gay, C.; Hagelberg, R.; Harvey, J.; Hilgart, J.; Jacobsen, R.; Jost, B.; Knobloch, J.; Lehraus, I.; Lohse, T.; Maggi, M.; Markou, C.; Martinez, M.; Mato, P.; Meinhard, H.; Minten, A.; Miotto, A.; Miquel, R.; Moser, H.-G.; Palazzi, P.; Pater, J. R.; Perlas, J. A.; Pusztaszeri, J.-F.; Ranjard, F.; Redlinger, G.; Rolandi, L.; Rothberg, J.; Ruan, T.; Saich, M.; Schlatter, D.; Schmelling, M.; Sefkow, F.; Tejessy, W.; Tomalin, I. R.; Veenhof, R.; Wachsmuth, H.; Wasserbaech, S.; Wiedenmann, W.; Wildish, T.; Witzeling, W.; Wotschack, J.; Atjaltouni, Z.; Badaud, F.; Bardadin-Otwinowska, M.; El Fellous, R.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Prulhière, F.; Saadi, F.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Møllerud, R.; Nilsson, B. S.; Kyriakis, A.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Badier, J.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Fouque, G.; Orteu, S.; Rougé, A.; Rumpf, M.; Tanaka, R.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Veitch, E.; Focardi, E.; Moneta, L.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Ikeda, M.; Levinthal, D.; Antonelli, A.; Baldini, R.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Cerutti, F.; Chiarella, V.; D'Ettorre-Piazzoli, B.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Picchi, P.; Colrain, P.; Ten Have, I.; Lynch, J. G.; Maitland, W.; Morton, W. T.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Smith, M. G.; Thompson, A. S.; Turnbull, R. M.; Brandl, B.; Braun, O.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Maumary, Y.; Putzer, A.; Rensch, B.; Stahl, A.; Tittel, K.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Cattaneo, M.; Colling, D. J.; Dornan, P. J.; Greene, A. M.; Hassard, J. F.; Lieske, N. M.; Moutoussi, A.; Nash, J.; Patton, S.; Payne, D. G.; Phillips, M. J.; San Martin, G.; Sedgbeer, J. K.; Wright, A. G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Vogl, R.; Bowdery, C. K.; Brodbeck, T. J.; Finch, A. J.; Foster, F.; Hughes, G.; Jackson, D.; Keemer, N. R.; Nuttall, M.; Petl, A.; Sloan, T.; Snow, S. W.; Whelan, E. P.; Kleinknecht, K.; Raab, J.; Renk, B.; Sander, H.-G.; Schmidt, H.; Steeg, F.; Walther, S. M.; Wanke, R.; Wolf, B.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Carr, J.; Coyle, P.; Drinkard, J.; Etienne, F.; Nicod, D.; Papalexiou, S.; Payre, P.; Roos, L.; Rousseau, D.; Schwemling, P.; Talby, M.; Adlung, S.; Assmann, R.; Bauer, C.; Blum, W.; Brown, D.; Cattaneo, P.; Dehning, B.; Dietl, H.; Dydak, F.; Frank, M.; Halley, A. W.; Jakobs, K.; Lauber, J.; Lütjens, G.; Lutz, G.; Männer, W.; Richter, R.; Schröder, J.; Schwarz, A. S.; Settles, R.; Seywerd, H.; Stielin, U.; Stiegler, U.; St. Denis, R.; Wolf, G.; Alemany, R.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jaffe, D. E.; Janot, P.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Schune, M.-H.; Veillet, J.-J.; Videau, I.; Zhang, Z.; Abbaneo, D.; Bagliesi, G.; Batignani, G.; Bottigli, U.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; dell'Orso, R.; Ferrante, I.; Fidecaro, F.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Mannelli, E. B.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Sanguinetti, G.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Valassi, A.; Vannini, C.; Venturi, A.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Gao, Y.; Green, M. G.; March, P. V.; Mir, Ll. M.; Medcalf, T.; Quazi, I. S.; Strong, J. A.; West, L. R.; Botteril, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Norton, P. R.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Duarte, H.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Rosowsky, A.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Si Mohand, D.; Vallage, B.; Johnson, R. P.; Litke, A. M.; Taylor, G.; Wear, J.; Ashman, J. G.; Babbage, W.; Booth, C. N.; Buttar, C.; Cartwright, S.; Combley, F.; Dawson, I.; Thompson, L. F.; Barberio, E.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Lutters, G.; Rivera, F.; Schäfer, U.; Smolik, L.; Bosisio, L.; della Marina, R.; Giannini, G.; Gobbo, B.; Ragusa, F.; Bellatoni, L.; Chen, W.; Conway, J. S.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; Grahl, J.; Harton, J. L.; Hayes, O. J.; Nachtman, J. M.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Scott, I.; Sharma, V.; Shi, Z. H.; Turk, J. D.; Walsh, A. M.; Weber, F. V.; Sau, Lan, Wu; Wu, X.; Zheng, M.; Zobernig, G.

    1993-09-01

    The ALEPH detector at LEP is used to study single photon events in e+e- collisions at the Z resonance. In a total data sample of 15.7 pb-1 taken in 1990 and 1991 scanning the resonance, 400 events were recorded where each has a single deposition of more than 1.5 GeV measured in the polar angular region cosθγ < 0.74 of the electromagnetic calorimeter. It is shown that this number of events cab be accounted for by known processes. After subtraction of background events, the invisible width of the Z is determined to be 45 +/- 34(stat.) +/- 34(syst.) MeV. Using Z. resonance parameters derived by ALEPH, the corresponding number oflight neutrino generations is found to be 2.68 +/- 0.20(stat.) +/- 0.20(syst.). Supported by the US Department of Energy, contract DE-ACO2-76ER00881.

  4. Photon counting and energy discriminating X-ray detectors. Benefits and applications

    International Nuclear Information System (INIS)

    Walter, David; Zscherpel, Uwe; Ewert, Uwe

    2016-01-01

    Since a few years the direct detection of X-ray photons into electrical signals is possible by usage of highly absorbing photo conducting materials (e.g. CdTe) as detection layer of an underlying CMOS semiconductor X-ray detector. Even NDT energies up to 400 keV are possible today, as well. The image sharpness and absorption efficiency is improved by the replacement of the unsharp scintillation layer (as used at indirect detecting detectors) by a photo conducting layer of much higher thickness. If the read-out speed is high enough (ca. 50 - 100 ns dead time) single X-ray photons can be counted and their energy measured. Read-out noise and dark image correction can be avoided. By setting energy thresholds selected energy ranges of the X-ray spectrum can be detected or suppressed. This allows material discrimination by dual-energy techniques or the reduction of image contributions of scattered radiation, which results in an enhanced contrast sensitivity. To use these advantages in an effective way, a special calibration procedure has to be developed, which considers also time dependent processes in the detection layer. This contribution presents some of these new properties of direct detecting digital detector arrays (DDAs) and shows first results on testing fiber reinforced composites as well as first approaches to dual energy imaging.

  5. Improving the resolution in soft X-ray emission spectrometers through photon-counting using an Electron Multiplying CCD

    International Nuclear Information System (INIS)

    Hall, D J; Soman, M; Tutt, J; Murray, N; Holland, A; Schmitt, T; Raabe, J; Strocov, V N; Schmitt, B

    2012-01-01

    In 2007, a study of back-illuminated Charge-Coupled Devices (CCDs) for soft X-ray photon detection demonstrated the improvements that could be brought over more traditional micro-channel plate detectors for X-ray spectrometers based on diffraction gratings and position sensitive detectors. Whilst the spatial resolution was reported to be improved dramatically, an intrinsic limit of approximately 25 micrometers was found due to the spreading of the charge cloud generated in the CCD across several pixels. To overcome this resolution limit, it is necessary to move away from the current integrated imaging methods and consider a photon-counting approach, recording the photon interaction locations to the sub-pixel level. To make use of photon-counting techniques it is important that the individual events are separable. To maintain the throughput of the spectrometer for high intensity lines, higher frame rates and therefore higher readout speeds are required. With CCD based systems, the increased noise at high readout speeds can limit the photon-counting performance. The Electron-Multiplying CCD shares a similar architecture with the standard CCD but incorporates a g ain register . This novel addition allows controllable gain to be applied to the signal before the read noise is introduced, therefore allowing individual events to be resolved above the noise even at much higher readout rates. In the past, the EM-CCD has only been available with imaging areas too small to be practical in soft X-ray emission spectrometers. The current drive for large area Electron-Multiplying CCDs is opening this technology to new photon-counting applications, requiring in-depth analysis of the processes and techniques involved. Early results indicate that through the introduction of photon-counting techniques the resolution in such systems can be dramatically improved.

  6. Development of superconducting tunnel junction as photon counting detector in astronomy

    International Nuclear Information System (INIS)

    Jorel, C.

    2004-12-01

    This work describes the development of S/Al-AlOx-Al/S Superconducting Tunnel Junctions (STJ) to count photons for astronomical applications in the near-infrared. The incoming light energy is converted into excited charges in a superconducting layer (S, either Nb or Ta) with a population proportional to the deposited energy. The photon energy can thus be evaluated by integrating the tunnel current induced in a voltage biased junction at a very low temperature (100 mK). The performance of STJ for light detection is discussed in the first chapter and compared with the best performances obtained with other techniques based on either superconductors. At the beginning of the thesis, a previous manufacturing process made it possible to obtain good quality Nb based junctions and preliminary results for photon counting. The objective of the thesis was to replace Nb as absorber with Ta, an intrinsically more sensitive material, and secondly to develop a new and more efficient manufacturing process. We first focused on the optimization of the Tantalum thin film quality. Structural analysis showed that these films can be grown epitaxially by magnetron sputtering onto an R-plane sapphire substrate heated to 600 Celsius degrees and covered by a thin Nb buffer layer. Electrical transport measurement from room to low temperatures gave excellent Relative Resistive Ratios of about 50 corresponding to mean free path of the order of 100 nm. Then, we conceived an original manufacturing process batch on 3 inch diameter sapphire substrate with five mask levels. These masks made it possible to produce single pixel STJ of different sizes (from 25*25 to 50*50 square microns) and shapes. We also produced multiple junctions onto a common absorber as well as 9-pixel arrays. Thanks to the development of this process we obtained a very large percentage of quality junctions (>90%) with excellent measured normal resistances of a few micro-ohm cm 2 and low leakage currents of the order of one n

  7. Development of low-dose photon-counting contrast-enhanced tomosynthesis with spectral imaging.

    Science.gov (United States)

    Schmitzberger, Florian F; Fallenberg, Eva Maria; Lawaczeck, Rüdiger; Hemmendorff, Magnus; Moa, Elin; Danielsson, Mats; Bick, Ulrich; Diekmann, Susanne; Pöllinger, Alexander; Engelken, Florian J; Diekmann, Felix

    2011-05-01

    To demonstrate the feasibility of low-dose photon-counting tomosynthesis in combination with a contrast agent (contrast material-enhanced tomographic mammography) for the differentiation of breast cancer. All studies were approved by the institutional review board, and all patients provided written informed consent. A phantom model with wells of iodinated contrast material (3 mg of iodine per milliliter) 1, 2, 5, 10, and 15 mm in diameter was assessed. Nine patients with malignant lesions and one with a high-risk lesion (atypical papilloma) were included (all women; mean age, 60.7 years). A multislit photon-counting tomosynthesis system was utilized (spectral imaging) to produce both low- and high-energy tomographic data (below and above the k edge of iodine, respectively) in a single scan, which allowed for dual-energy visualization of iodine. Images were obtained prior to contrast material administration and 120 and 480 seconds after contrast material administration. Four readers independently assessed the images along with conventional mammograms, ultrasonographic images, and magnetic resonance images. Glandular dose was estimated. Contrast agent was visible in the phantom model with simulated spherical tumor diameters as small as 5 mm. The average glandular dose was measured as 0.42 mGy per complete spectral imaging tomosynthesis scan of one breast. Because there were three time points (prior to contrast medium administration and 120 and 480 seconds after contrast medium administration), this resulted in a total dose of 1.26 mGy for the whole procedure in the breast with the abnormality. Seven of 10 cases were categorized as Breast Imaging Reporting and Data System score of 4 or higher by all four readers when reviewing spectral images in combination with mammograms. One lesion near the chest wall was not captured on the spectral image because of a positioning problem. The use of contrast-enhanced tomographic mammography has been demonstrated successfully in

  8. Quantitative material decomposition using spectral computed tomography with an energy-resolved photon-counting detector

    International Nuclear Information System (INIS)

    Lee, Seungwan; Choi, Yu-Na; Kim, Hee-Joung

    2014-01-01

    Dual-energy computed tomography (CT) techniques have been used to decompose materials and characterize tissues according to their physical and chemical compositions. However, these techniques are hampered by the limitations of conventional x-ray detectors operated in charge integrating mode. Energy-resolved photon-counting detectors provide spectral information from polychromatic x-rays using multiple energy thresholds. These detectors allow simultaneous acquisition of data in different energy ranges without spectral overlap, resulting in more efficient material decomposition and quantification for dual-energy CT. In this study, a pre-reconstruction dual-energy CT technique based on volume conservation was proposed for three-material decomposition. The technique was combined with iterative reconstruction algorithms by using a ray-driven projector in order to improve the quality of decomposition images and reduce radiation dose. A spectral CT system equipped with a CZT-based photon-counting detector was used to implement the proposed dual-energy CT technique. We obtained dual-energy images of calibration and three-material phantoms consisting of low atomic number materials from the optimal energy bins determined by Monte Carlo simulations. The material decomposition process was accomplished by both the proposed and post-reconstruction dual-energy CT techniques. Linear regression and normalized root-mean-square error (NRMSE) analyses were performed to evaluate the quantitative accuracy of decomposition images. The calibration accuracy of the proposed dual-energy CT technique was higher than that of the post-reconstruction dual-energy CT technique, with fitted slopes of 0.97–1.01 and NRMSEs of 0.20–4.50% for all basis materials. In the three-material phantom study, the proposed dual-energy CT technique decreased the NRMSEs of measured volume fractions by factors of 0.17–0.28 compared to the post-reconstruction dual-energy CT technique. It was concluded that the

  9. Modelling and simulation of pixelated photon counting X-ray detectors for imaging; Modellierung und Simulation physikalischer Eigenschaften photonenzaehlender Roentgenpixeldetektoren fuer die Bildgebung

    Energy Technology Data Exchange (ETDEWEB)

    Durst, Juergen

    2008-07-22

    First of all the physics processes generating the energy deposition in the sensor volume are investigated. The spatial resolution limits of photon interactions and the range of secondary electrons are discussed. The signatures in the energy deposition spectrum in pixelated detectors with direct conversion layers are described. The energy deposition for single events can be generated by the Monte-Carlo-Simulation package ROSI. The basic interactions of photons with matter are evaluated, resulting in the ability to use ROSI as a basis for the simulation of photon counting pixel detectors with direct conversion. In the context of this thesis a detector class is developed to simulate the response of hybrid photon counting pixel detectors using high-Z sensor materials like Cadmium Telluride (CdTe) or Gallium Arsenide (GaAs) in addition to silicon. To enable the realisation of such a simulation, the relevant physics processes and properties have to be implemented: processes in the sensor layer (provided by EGS4/LSCAT in ROSI), generation of charge carriers as electron hole pairs, diffusion and repulsion of charge carriers during drift and lifetime. Furthermore, several noise contributions of the electronics can be taken into account. The result is a detector class which allows the simulation of photon counting detectors. In this thesis the multiplicity framework is developed, including a formula to calculate or measure the zero frequency detective quantum efficiency (DQE). To enable the measurement of the multiplicity of detected events a cluster analysis program was developed. Random and systematic errors introduced by the cluster analysis are discussed. It is also shown that the cluster analysis method can be used to determine the averaged multiplicity with high accuracy. The method is applied to experimental data. As an example using the implemented detector class, the discriminator threshold dependency of the DQE and modulation transfer function is investigated in

  10. Measurement of effective detective quantum efficiency for a photon counting scanning mammography system and comparison with two flat panel full-field digital mammography systems

    Science.gov (United States)

    Wood, Tim J.; Moore, Craig S.; Saunderson, John R.; Beavis, Andrew W.

    2018-01-01

    Effective detective quantum efficiency (eDQE) describes the resolution and noise properties of an imaging system along with scatter and primary transmission, all measured under clinically appropriate conditions. Effective dose efficiency (eDE) is the eDQE normalised to mean glandular dose and has been proposed as a useful metric for the optimisation of clinical imaging systems. The aim of this study was to develop a methodology for measuring eDQE and eDE on a Philips microdose mammography (MDM) L30 photon counting scanning system, and to compare performance with two conventional flat panel systems. A custom made lead-blocker was manufactured to enable the accurate determination of dose measurements, and modulation transfer functions were determined free-in-air at heights of 2, 4 and 6 cm above the breast support platform. eDQE were calculated for a Philips MDM L30, Hologic Dimensions and Siemens Inspiration digital mammography system for 2, 4 and 6 cm thick poly(methyl methacrylate) (PMMA). The beam qualities (target/filter and kilovoltage) assessed were those selected by the automatic exposure control, and anti-scatter grids were used where available. Measurements of eDQE demonstrate significant differences in performance between the slit- and scan-directions for the photon counting imaging system. MTF has been shown to be the limiting factor in the scan-direction, which results in a rapid fall in eDQE at mid-to-high spatial frequencies. A comparison with two flat panel mammography systems demonstrates that this may limit image quality for small details, such as micro-calcifications, which correlates with a more conventional image quality assessment with the CDMAM phantom. eDE has shown the scanning photon counting system offers superior performance for low spatial frequencies, which will be important for the detection of large low contrast masses. Both eDQE and eDE are proposed as useful metrics that should enable optimisation of the Philips MDM L30.

  11. Plastic scintillation dosimetry: Optimal selection of scintillating fibers and scintillators

    International Nuclear Information System (INIS)

    Archambault, Louis; Arsenault, Jean; Gingras, Luc; Sam Beddar, A.; Roy, Rene; Beaulieu, Luc

    2005-01-01

    Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for four commercial models of scintillating fibers (BCF-12, BCF-60, SCSF-78, SCSF-3HF) and two models of plastic scintillators (BC-400, BC-408). The emission spectra of all six scintillators were obtained by using an optical spectrum analyzer and they were compared with theoretical behavior. For scintillation in the blue region, the signal intensity of a singly clad scintillating fiber (BCF-12) was 120% of that of the plastic scintillator (BC-400). For the multiclad fiber (SCSF-78), the signal reached 144% of that of the plastic scintillator. The intensity of the green scintillating fibers was lower than that of the plastic scintillator: 47% for the singly clad fiber (BCF-60) and 77% for the multiclad fiber (SCSF-3HF). The collected light was studied as a function of the scintillator length and radius for a cylindrical probe. We found that symmetric detectors with nearly the same spatial resolution in each direction (2 mm in diameter by 3 mm in length) could be made with a signal equivalent to those of the more commonly used asymmetric scintillators. With augmentation of the signal-to-noise ratio in consideration, this paper presents a series of comparisons that should provide insight into selection of a scintillator type and volume for development of a medical dosimeter

  12. An x-ray-based capsule for colorectal cancer screening incorporating single photon counting technology

    Science.gov (United States)

    Lifshitz, Ronen; Kimchy, Yoav; Gelbard, Nir; Leibushor, Avi; Golan, Oleg; Elgali, Avner; Hassoon, Salah; Kaplan, Max; Smirnov, Michael; Shpigelman, Boaz; Bar-Ilan, Omer; Rubin, Daniel; Ovadia, Alex

    2017-03-01

    An ingestible capsule for colorectal cancer screening, based on ionizing-radiation imaging, has been developed and is in advanced stages of system stabilization and clinical evaluation. The imaging principle allows future patients using this technology to avoid bowel cleansing, and to continue the normal life routine during procedure. The Check-Cap capsule, or C-Scan ® Cap, imaging principle is essentially based on reconstructing scattered radiation, while both radiation source and radiation detectors reside within the capsule. The radiation source is a custom-made radioisotope encased in a small canister, collimated into rotating beams. While traveling along the human colon, irradiation occurs from within the capsule towards the colon wall. Scattering of radiation occurs both inside and outside the colon segment; some of this radiation is scattered back and detected by sensors onboard the capsule. During procedure, the patient receives small amounts of contrast agent as an addition to his/her normal diet. The presence of contrast agent inside the colon dictates the dominant physical processes to become Compton Scattering and X-Ray Fluorescence (XRF), which differ mainly by the energy of scattered photons. The detector readout electronics incorporates low-noise Single Photon Counting channels, allowing separation between the products of these different physical processes. Separating between radiation energies essentially allows estimation of the distance from the capsule to the colon wall, hence structural imaging of the intraluminal surface. This allows imaging of structural protrusions into the colon volume, especially focusing on adenomas that may develop into colorectal cancer.

  13. CLARO: an ASIC for high rate single photon counting with multi-anode photomultipliers

    Science.gov (United States)

    Baszczyk, M.; Carniti, P.; Cassina, L.; Cotta Ramusino, A.; Dorosz, P.; Fiorini, M.; Gotti, C.; Kucewicz, W.; Malaguti, R.; Pessina, G.

    2017-08-01

    The CLARO is a radiation-hard 8-channel ASIC designed for single photon counting with multi-anode photomultiplier tubes. Each channel outputs a digital pulse when the input signal from the photomultiplier crosses a configurable threshold. The fast return to baseline, typically within 25 ns, and below 50 ns in all conditions, allows to count up to 107 hits/s on each channel, with a power consumption of about 1 mW per channel. The ASIC presented here is a much improved version of the first 4-channel prototype. The threshold can be precisely set in a wide range, between 30 ke- (5 fC) and 16 Me- (2.6 pC). The noise of the amplifier with a 10 pF input capacitance is 3.5 ke- (0.6 fC) RMS. All settings are stored in a 128-bit configuration and status register, protected against soft errors with triple modular redundancy. The paper describes the design of the ASIC at transistor-level, and demonstrates its performance on the test bench.

  14. Systematic implementation of spectral CT with a photon counting detector for liquid security inspection

    Science.gov (United States)

    Xu, Xiaofei; Xing, Yuxiang; Wang, Sen; Zhang, Li

    2018-06-01

    X-ray liquid security inspection system plays an important role in homeland security, while the conventional dual-energy CT (DECT) system may have a big deviation in extracting the atomic number and the electron density of materials in various conditions. Photon counting detectors (PCDs) have the capability of discriminating the incident photons of different energy. The technique becomes more and more mature in nowadays. In this work, we explore the performance of a multi-energy CT imaging system with a PCD for liquid security inspection in material discrimination. We used a maximum-likelihood (ML) decomposition method with scatter correction based on a cross-energy response model (CERM) for PCDs so that to improve the accuracy of atomic number and electronic density imaging. Experimental study was carried to examine the effectiveness and robustness of the proposed system. Our results show that the concentration of different solutions in physical phantoms can be reconstructed accurately, which could improve the material identification compared to current available dual-energy liquid security inspection systems. The CERM-base decomposition and reconstruction method can be easily used to different applications such as medical diagnosis.

  15. On the performance of bioanalytical fluorescence correlation spectroscopy measurements in a multiparameter photon-counting microscope

    Energy Technology Data Exchange (ETDEWEB)

    Mazouchi, Amir; Liu Baoxu; Bahram, Abdullah [Department of Physics, Institute for Optical Sciences, University of Toronto, Toronto (Canada); Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6 (Canada); Gradinaru, Claudiu C., E-mail: claudiu.gradinaru@utoronto.ca [Department of Physics, Institute for Optical Sciences, University of Toronto, Toronto (Canada); Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Rd. N., Mississauga, ON, L5L 1C6 (Canada)

    2011-02-28

    Fluorescence correlation spectroscopy (FCS) data acquisition and analysis routines were developed and implemented in a home-built, multiparameter photon-counting microscope. Laser excitation conditions were investigated for two representative fluorescent probes, Rhodamine110 and enhanced green fluorescent protein (EGFP). Reliable local concentrations and diffusion constants were obtained by fitting measured FCS curves, provided that the excitation intensity did not exceed 20% of the saturation level for each fluorophore. Accurate results were obtained from FCS measurements for sample concentrations varying from pM to {mu}M range, as well as for conditions of high background signals. These experimental constraints were found to be determined by characteristics of the detection system and by the saturation behavior of the fluorescent probes. These factors actually limit the average number of photons that can be collected from a single fluorophore passing through the detection volume. The versatility of our setup and the data analysis capabilities were tested by measuring the mobility of EGFP in the nucleus of Drosophila cells under conditions of high concentration and molecular crowding. As a bioanalytical application, we studied by FCS the binding affinity of a novel peptide-based drug to the cancer-regulating STAT3 protein and corroborated the results with fluorescence polarization analysis derived from the same photon data.

  16. Preliminary characterization of a single photon counting detection system for CT application

    International Nuclear Information System (INIS)

    Belcari, N.; Bisogni, M.G.; Carpentieri, C.; Del Guerra, A.; Delogu, P.; Panetta, D.; Quattrocchi, M.; Rosso, V.; Stefanini, A.

    2007-01-01

    The aim of this work is to evaluate the capability of a single photon counting acquisition system based on the Medipix2 read-out chip for Computed Tomography (CT) applications in Small Animal Imaging. We used a micro-focus X-ray source with a W anode. The detection system is based on the Medipix2 read-out chip, bump-bonded to a 1 mm thick silicon pixel detector. The read-out chip geometry is a matrix of 256x256 cells, 55 μmx55 μm each. This system in planar radiography shows a good detection efficiency (about 70%) at the anode voltage of 30 kV and a good spatial resolution (MTF=10% at 16.8 lp/mm). Starting from these planar performances we have characterized the system for the tomography applications with phantoms. We will present the results obtained as a function of magnification with two different background medium compositions. The effect of the reconstruction algorithm on image quality will be also discussed

  17. Characterization of spectrometric photon-counting X-ray detectors at different pitches

    International Nuclear Information System (INIS)

    Jurdit, M.; Moulin, V.; Ouvrier-Buffet, P.; Verger, L.; Brambilla, A.; Radisson, P.

    2017-01-01

    There is growing interest in energy-sensitive photon-counting detectors based on high flux X-ray imaging. Their potential applications include medical imaging, non-destructive testing and security. Innovative detectors of this type will need to count individual photons and sort them into selected energy bins, at several million counts per second and per mm 2 . Cd(Zn)Te detector grade materials with a thickness of 1.5 to 3 mm and pitches from 800 μm down to 200 μm were assembled onto interposer boards. These devices were tested using in-house-developed full-digital fast readout electronics. The 16-channel demonstrators, with 256 energy bins, were experimentally characterized by determining spectral resolution, count rate, and charge sharing, which becomes challenging at low pitch. Charge sharing correction was found to efficiently correct X-ray spectra up to 40 × 10 6 incident photons.s −1 .mm −2 .

  18. Preliminary evaluation of a novel energy-resolved photon-counting gamma ray detector.

    Science.gov (United States)

    Meng, L-J; Tan, J W; Spartiotis, K; Schulman, T

    2009-06-11

    In this paper, we present the design and preliminary performance evaluation of a novel energy-resolved photon-counting (ERPC) detector for gamma ray imaging applications. The prototype ERPC detector has an active area of 4.4 cm × 4.4 cm, which is pixelated into 128 × 128 square pixels with a pitch size of 350 µm × 350µm. The current detector consists of multiple detector hybrids, each with a CdTe crystal of 1.1 cm × 2.2 cm × 1 mm, bump-bonded onto a custom-designed application-specific integrated circuit (ASIC). The ERPC ASIC has 2048 readout channels arranged in a 32 × 64 array. Each channel is equipped with pre- and shaping-amplifiers, a discriminator, peak/hold circuitry and an analog-to-digital converter (ADC) for digitizing the signal amplitude. In order to compensate for the pixel-to-pixel variation, two 8-bit digital-to-analog converters (DACs) are implemented into each channel for tuning the gain and offset. The ERPC detector is designed to offer a high spatial resolution, a wide dynamic range of 12-200 keV and a good energy resolution of 3-4 keV. The hybrid detector configuration provides a flexible detection area that can be easily tailored for different imaging applications. The intrinsic performance of a prototype ERPC detector was evaluated with various gamma ray sources, and the results are presented.

  19. Initial results from a prototype whole-body photon-counting computed tomography system.

    Science.gov (United States)

    Yu, Z; Leng, S; Jorgensen, S M; Li, Z; Gutjahr, R; Chen, B; Duan, X; Halaweish, A F; Yu, L; Ritman, E L; McCollough, C H

    X-ray computed tomography (CT) with energy-discriminating capabilities presents exciting opportunities for increased dose efficiency and improved material decomposition analyses. However, due to constraints imposed by the inability of photon-counting detectors (PCD) to respond accurately at high photon flux, to date there has been no clinical application of PCD-CT. Recently, our lab installed a research prototype system consisting of two x-ray sources and two corresponding detectors, one using an energy-integrating detector (EID) and the other using a PCD. In this work, we report the first third-party evaluation of this prototype CT system using both phantoms and a cadaver head. The phantom studies demonstrated several promising characteristics of the PCD sub-system, including improved longitudinal spatial resolution and reduced beam hardening artifacts, relative to the EID sub-system. More importantly, we found that the PCD sub-system offers excellent pulse pileup control in cases of x-ray flux up to 550 mA at 140 kV, which corresponds to approximately 2.5×10 11 photons per cm 2 per second. In an anthropomorphic phantom and a cadaver head, the PCD sub-system provided image quality comparable to the EID sub-system for the same dose level. Our results demonstrate the potential of the prototype system to produce clinically-acceptable images in vivo .

  20. Maximum Likelihood Time-of-Arrival Estimation of Optical Pulses via Photon-Counting Photodetectors

    Science.gov (United States)

    Erkmen, Baris I.; Moision, Bruce E.

    2010-01-01

    Many optical imaging, ranging, and communications systems rely on the estimation of the arrival time of an optical pulse. Recently, such systems have been increasingly employing photon-counting photodetector technology, which changes the statistics of the observed photocurrent. This requires time-of-arrival estimators to be developed and their performances characterized. The statistics of the output of an ideal photodetector, which are well modeled as a Poisson point process, were considered. An analytical model was developed for the mean-square error of the maximum likelihood (ML) estimator, demonstrating two phenomena that cause deviations from the minimum achievable error at low signal power. An approximation was derived to the threshold at which the ML estimator essentially fails to provide better than a random guess of the pulse arrival time. Comparing the analytic model performance predictions to those obtained via simulations, it was verified that the model accurately predicts the ML performance over all regimes considered. There is little prior art that attempts to understand the fundamental limitations to time-of-arrival estimation from Poisson statistics. This work establishes both a simple mathematical description of the error behavior, and the associated physical processes that yield this behavior. Previous work on mean-square error characterization for ML estimators has predominantly focused on additive Gaussian noise. This work demonstrates that the discrete nature of the Poisson noise process leads to a distinctly different error behavior.

  1. On Approaching the Ultimate Limits of Communication Using a Photon-Counting Detector

    Science.gov (United States)

    Erkmen, Baris I.; Moision, Bruce E.; Dolinar, Samuel J.; Birnbaum, Kevin M.; Divsalar, Dariush

    2012-01-01

    Coherent states achieve the Holevo capacity of a pure-loss channel when paired with an optimal measurement, but a physical realization of this measurement scheme is as of yet unknown, and it is also likely to be of high complexity. In this paper, we focus on the photon-counting measurement and study the photon and dimensional efficiencies attainable with modulations over classical- and nonclassical-state alphabets. We analyze two binary modulation architectures that improve upon the dimensional versus photon efficiency tradeoff achievable with the state-of-the-art coherent-state on-off keying modulation. We show that at high photon efficiency these architectures achieve an efficiency tradeoff that differs from the best possible tradeoff--determined by the Holevo capacity--by only a constant factor. The first architecture we analyze is a coherent-state transmitter that relies on feedback from the receiver to control the transmitted energy. The second architecture uses a single-photon number-state source.

  2. Approaching the Ultimate Limits of Communication Efficiency with a Photon-Counting Detector

    Science.gov (United States)

    Erkmen, Baris; Moision, Bruce; Dolinar, Samuel J.; Birnbaum, Kevin M.; Divsalar, Dariush

    2012-01-01

    Coherent states achieve the Holevo capacity of a pure-loss channel when paired with an optimal measurement, but a physical realization of this measurement is as of yet unknown, and it is also likely to be of high complexity. In this paper, we focus on the photon-counting measurement and study the photon and dimensional efficiencies attainable with modulations over classical- and nonclassical-state alphabets. We first review the state-of-the-art coherent on-off-keying (OOK) with a photoncounting measurement, illustrating its asymptotic inefficiency relative to the Holevo limit. We show that a commonly made Poisson approximation in thermal noise leads to unbounded photon information efficiencies, violating the conjectured Holevo limit. We analyze two binary-modulation architectures that improve upon the dimensional versus photon efficiency tradeoff achievable with conventional OOK. We show that at high photon efficiency these architectures achieve an efficiency tradeoff that differs from the best possible tradeoff--determined by the Holevo capacity--by only a constant factor. The first architecture we analyze is a coherent-state transmitter that relies on feedback from the receiver to control the transmitted energy. The second architecture uses a single-photon number-state source.

  3. X-ray Imaging Using a Hybrid Photon Counting GaAs Pixel Detector

    CERN Document Server

    Schwarz, C; Göppert, R; Heijne, Erik H M; Ludwig, J; Meddeler, G; Mikulec, B; Pernigotti, E; Rogalla, M; Runge, K; Smith, K M; Snoeys, W; Söldner-Rembold, S; Watt, J

    1999-01-01

    The performance of hybrid GaAs pixel detectors as X-ray imaging sensors were investigated at room temperature. These hybrids consist of 300 mu-m thick GaAs pixel detectors, flip-chip bonded to a CMOS Single Photon Counting Chip (PCC). This chip consists of a matrix of 64 x 64 identical square pixels (170 mu-m x 170 mu-m) and covers a total area of 1.2 cm**2. The electronics in each cell comprises a preamplifier, a discriminator with a 3-bit threshold adjust and a 15-bit counter. The detector is realized by an array of Schottky diodes processed on semi-insulating LEC-GaAs bulk material. An IV-charcteristic and a detector bias voltage scan showed that the detector can be operated with voltages around 200 V. Images of various objects were taken by using a standard X-ray tube for dental diagnostics. The signal to noise ratio (SNR) was also determined. The applications of these imaging systems range from medical applications like digital mammography or dental X-ray diagnostics to non destructive material testing (...

  4. Note: Space qualified photon counting detector for laser time transfer with picosecond precision and stability.

    Science.gov (United States)

    Prochazka, Ivan; Kodet, Jan; Blazej, Josef

    2016-05-01

    The laser time transfer link is under construction for the European Space Agency in the frame of Atomic Clock Ensemble in Space. We have developed and tested the flying unit of the photon counting detector optimized for this space mission. The results are summarized in this Note. An extreme challenge was to build a detector package, which is rugged, small and which provides long term detection delay stability on picosecond level. The device passed successfully all the tests required for space missions on the low Earth orbits. The detector is extremely rugged and compact. Its long term detection delay stability is excellent, it is better than ±1 ps/day, in a sense of time deviation it is better than 0.5 ps for averaging times of 2000 s to several hours. The device is capable to operate in a temperature range of -55 °C up to +60 °C, the change of the detection delay with temperature is +0.5 ps/K. The device is ready for integration into the space structure now.

  5. Distributed plastic optical fibre measurement of pH using a photon counting OTDR

    International Nuclear Information System (INIS)

    Saunders, C; Scully, P J

    2005-01-01

    Distributed measurement of pH was demonstrated at a sensitised region 4m from the distal end of a 20m length of plastic optical fibre. The cladding was removed from the fibre over 150mm and the bare core was exposed to an aqueous solution of methyl red at three values of pH, between 2.89 and 9.70. The optical fibre was interrogated at 648nm using a Luciol photon counting optical time domain reflectometer, and demonstrated that the sensing region was attenuated as a function of pH. The attenuation varied from 16.3 dB at pH 2.89 to 8.6 dB at pH 9.70; this range equated to -1.13 ± 0.04 dB/pH. It is thus possible to determine both the position to ± 12mm and pH to an estimated ± 0.5pH at the sensing region

  6. Photon counting with a FDIRC Cherenkov prototype readout by SiPM arrays

    Energy Technology Data Exchange (ETDEWEB)

    Marrocchesi, P.S., E-mail: marrocchesi@pi.infn.it [Department of Physical Sciences, Earth and Environment, Via Roma 56, I-53100 Siena (Italy); INFN Sezione di Pisa, Largo Bruno Pontecorvo 3, I-56127 Pisa (Italy); Bagliesi, M.G. [Department of Physical Sciences, Earth and Environment, Via Roma 56, I-53100 Siena (Italy); Basti, A. [Department of Physics, University of Pisa, Largo Bruno Pontecorvo 3, I-56127 Pisa (Italy); INFN Sezione di Pisa, Largo Bruno Pontecorvo 3, I-56127 Pisa (Italy); Bigongiari, G.; Bonechi, S.; Brogi, P. [Department of Physical Sciences, Earth and Environment, Via Roma 56, I-53100 Siena (Italy); INFN Sezione di Pisa, Largo Bruno Pontecorvo 3, I-56127 Pisa (Italy); Checchia, C.; Collazuol, G. [Department of Physics and Astronomy, University of Padova, Padova, Italy, and INFN-Padova, 35131 Padova (Italy); Maestro, P. [Department of Physical Sciences, Earth and Environment, Via Roma 56, I-53100 Siena (Italy); INFN Sezione di Pisa, Largo Bruno Pontecorvo 3, I-56127 Pisa (Italy); Morsani, F. [INFN Sezione di Pisa, Largo Bruno Pontecorvo 3, I-56127 Pisa (Italy); Piemonte, C. [Fondazione Bruno Kessler (FBK), I-38122 Trento (Italy); Stolzi, F.; Suh, J.E; Sulaj, A. [Department of Physical Sciences, Earth and Environment, Via Roma 56, I-53100 Siena (Italy); INFN Sezione di Pisa, Largo Bruno Pontecorvo 3, I-56127 Pisa (Italy)

    2017-02-11

    A prototype of a Focused Internal Reflection Cherenkov, equipped with 16 arrays of NUV-SiPM, was tested at CERN SPS in March 2015 with beams of relativistic ions at 13, 19 and 30 GeV/n obtained from fragmentation of an Ar primary beam. The detector, designed to identify cosmic nuclei, features a Fused Silica radiator bar optically connected to a cylindrical mirror of the same material and an imaging focal plane of dimensions ∼4 cm×3 cm covered with a total of 1024 SiPM photosensors. Thanks to the outstanding performance of the SiPM arrays, the detector could be operated in photon counting mode as a fully digital device. The Cherenkov pattern was recorded together with the total number of detected photoelectrons increasing as Z{sup 2} as a function of the atomic number Z of the beam particle. In this paper, we report on the characterization and test of the SiPM arrays and the performance of the Cherenkov prototype for the charge identification of the beam particles.

  7. TU-G-207-01: CT Imaging Using Energy-Sensitive Photon-Counting Detectors

    International Nuclear Information System (INIS)

    Taguchi, K.

    2015-01-01

    Last few years has witnessed the development of novel of X-ray imaging modalities, such as spectral CT, phase contrast CT, and X-ray acoustic/fluorescence/luminescence imaging. This symposium will present the recent advances of these emerging X-ray imaging modalities and update the attendees with knowledge in various related topics, including X-ray photon-counting detectors, X-ray physics underlying the emerging applications beyond the traditional X-ray imaging, image reconstruction for the novel modalities, characterization and evaluation of the systems, and their practical implications. In addition, the concept and practical aspects of X-ray activatable targeted nanoparticles for molecular X-ray imaging will be discussed in the context of X-ray fluorescence and luminescence CT. Learning Objectives: Present background knowledge of various emerging X-ray imaging techniques, such as spectral CT, phase contrast CT and X-ray fluorescence/luminescence CT. Discuss the practical need, technical aspects and current status of the emerging X-ray imaging modalities. Describe utility and future impact of the new generation of X-ray imaging applications

  8. Characterisation of a single photon counting pixel system for imaging of low-contrast objects

    CERN Document Server

    Mikulec, B; Dipasquale, G; Schwarz, C; Watt, J

    2001-01-01

    In the framework of the Medipix collaboration the PCC, a single photon counting pixel chip, has been developed with the aim of improving the contrast resolution in medical imaging applications. The PCC consists of a matrix of 64x64 square pixels with 170 mm side length, each pixel comprising a 15 bit counter and a pulse height discriminator. The chip has been bump bonded to equally segmented 200 mm thick SI-LEC GaAs detectors showing a very high absorption energy for X-rays used in diagnostics. An absolute calibration of the system with a radioactive source and a synchrotron beam are described resulting in the value of the test input capacitance of ~24.7 fF. Using this value a full characterisation of the system from electrical measurements is presented. The entire system can reach a minimum threshold of ~2100 e- with ~250e- rms noise. One of the characteristics of the PCC is the possibility to adjust the thresholds of all pixels on a pixel-by-pixel basis with 3-bit precision. The threshold distribution after...

  9. Material decomposition and virtual non-contrast imaging in photon counting computed tomography: an animal study

    Science.gov (United States)

    Gutjahr, R.; Polster, C.; Kappler, S.; Pietsch, H.; Jost, G.; Hahn, K.; Schöck, F.; Sedlmair, M.; Allmendinger, T.; Schmidt, B.; Krauss, B.; Flohr, T. G.

    2016-03-01

    The energy resolving capabilities of Photon Counting Detectors (PCD) in Computed Tomography (CT) facilitate energy-sensitive measurements. The provided image-information can be processed with Dual Energy and Multi Energy algorithms. A research PCD-CT firstly allows acquiring images with a close to clinical configuration of both the X-ray tube and the CT-detector. In this study, two algorithms (Material Decomposition and Virtual Non-Contrast-imaging (VNC)) are applied on a data set acquired from an anesthetized rabbit scanned using the PCD-CT system. Two contrast agents (CA) are applied: A gadolinium (Gd) based CA used to enhance contrasts for vascular imaging, and xenon (Xe) and air as a CA used to evaluate local ventilation of the animal's lung. Four different images are generated: a) A VNC image, suppressing any traces of the injected Gd imitating a native scan, b) a VNC image with a Gd-image as an overlay, where contrast enhancements in the vascular system are highlighted using colored labels, c) another VNC image with a Xe-image as an overlay, and d) a 3D rendered image of the animal's lung, filled with Xe, indicating local ventilation characteristics. All images are generated from two images based on energy bin information. It is shown that a modified version of a commercially available dual energy software framework is capable of providing images with diagnostic value obtained from the research PCD-CT system.

  10. K-edge energy-based calibration method for photon counting detectors

    Science.gov (United States)

    Ge, Yongshuai; Ji, Xu; Zhang, Ran; Li, Ke; Chen, Guang-Hong

    2018-01-01

    In recent years, potential applications of energy-resolved photon counting detectors (PCDs) in the x-ray medical imaging field have been actively investigated. Unlike conventional x-ray energy integration detectors, PCDs count the number of incident x-ray photons within certain energy windows. For PCDs, the interactions between x-ray photons and photoconductor generate electronic voltage pulse signals. The pulse height of each signal is proportional to the energy of the incident photons. By comparing the pulse height with the preset energy threshold values, x-ray photons with specific energies are recorded and sorted into different energy bins. To quantitatively understand the meaning of the energy threshold values, and thus to assign an absolute energy value to each energy bin, energy calibration is needed to establish the quantitative relationship between the threshold values and the corresponding effective photon energies. In practice, the energy calibration is not always easy, due to the lack of well-calibrated energy references for the working energy range of the PCDs. In this paper, a new method was developed to use the precise knowledge of the characteristic K-edge energy of materials to perform energy calibration. The proposed method was demonstrated using experimental data acquired from three K-edge materials (viz., iodine, gadolinium, and gold) on two different PCDs (Hydra and Flite, XCounter, Sweden). Finally, the proposed energy calibration method was further validated using a radioactive isotope (Am-241) with a known decay energy spectrum.

  11. A simulation study of high-resolution x-ray computed tomography imaging using irregular sampling with a photon-counting detector

    International Nuclear Information System (INIS)

    Lee, Seungwan; Choi, Yu-Na; Kim, Hee-Joung

    2013-01-01

    The purpose of this study was to improve the spatial resolution for the x-ray computed tomography (CT) imaging with a photon-counting detector using an irregular sampling method. The geometric shift-model of detector was proposed to produce the irregular sampling pattern and increase the number of samplings in the radial direction. The conventional micro-x-ray CT system and the novel system with the geometric shift-model of detector were simulated using analytic and Monte Carlo simulations. The projections were reconstructed using filtered back-projection (FBP), algebraic reconstruction technique (ART), and total variation (TV) minimization algorithms, and the reconstructed images were compared in terms of normalized root-mean-square error (NRMSE), full-width at half-maximum (FWHM), and coefficient-of-variation (COV). The results showed that the image quality improved in the novel system with the geometric shift-model of detector, and the NRMSE, FWHM, and COV were lower for the images reconstructed using the TV minimization technique in the novel system with the geometric shift-model of detector. The irregular sampling method produced by the geometric shift-model of detector can improve the spatial resolution and reduce artifacts and noise for reconstructed images obtained from an x-ray CT system with a photon-counting detector. -- Highlights: • We proposed a novel sampling method based on a spiral pattern to improve the spatial resolution. • The novel sampling method increased the number of samplings in the radial direction. • The spatial resolution was improved by the novel sampling method

  12. Automated and angular time-synchronized directional gamma-ray scintillation sensor

    International Nuclear Information System (INIS)

    Kronenberg, S.; Brucker, G.J.

    1998-01-01

    The authors' previous research resulted in directional sensors for gamma rays and X rays that have a 4π solid angle of acceptance and, at the same time, a high angular resolution that is limited only by their ability to measure small angles. Angular resolution of ∼1 s of arc was achieved. These sensors are capable of operating and accurately detecting high and very low intensity radiation patterns. Such a system can also be used to image broad area sources and their scattering patterns. The principle of operation and design of directional sensors used in this study was described elsewhere; however, for convenience, a part of that text is repeated here. It was shown analytically that the angular distribution of radiation incident on the sensor is proportional to the first derivative of the scan data, that is, of the events' count rate versus orientation of the detector. The previously published results were obtained with a annual operating system. The detector assembly was set at a specific angle, and a pulse rate count was made. This was repeated at numerous other angles of orientation, a time-consuming and labor-intensive process. Recently, the authors automated this system, which is based on the detection of scintillations. The detector, which consists of a stack of plates of Lucite, plastic scintillator, and lead foils, rotates by means of a motor in front of a stationary photomultiplier tube (PMT). One revolution per second was chosen for the motor. At time zero, a trigger indicates that a revolution has started. The angle of orientation of the detector in the laboratory system is proportional to the time during one revolution. The process repeats itself a desired number of times. The trigger signal initiates a scan of a multichannel scalar (MCS). The detector assembly is allowed to rotate in the radiation field, and the MCS scans are repeated in an accumulated mode of operation until enough events are collected for the location of the radiation source to be

  13. Time-over-threshold readout to enhance the high flux capabilities of single-photon-counting detectors

    International Nuclear Information System (INIS)

    Bergamaschi, Anna; Dinapoli, Roberto; Greiffenberg, Dominic; Henrich, Beat; Johnson, Ian; Mozzanica, Aldo; Radicci, Valeria; Schmitt, Bernd; Shi, Xintian; Stoppani, Laura

    2011-01-01

    The MYTHEN photon-counting ASIC operated in time-over-threshold mode shows an innovative approach towards the development of a detector operating with very high photon intensities while maintaining the single-photon sensitivity for synchrotron radiation experiments. The MYTHEN single-photon-counting (SPC) detector has been characterized using the time-over-threshold (ToT) readout method, i.e. measuring the time that the signal produced by the detected X-rays remains above the comparator threshold. In the following it is shown that the ToT readout preserves the sensitivity, dynamic range and capability of background suppression of the SPC mode, while enhancing the count-rate capability, which is the main limitation of state-of-the-art SPC systems

  14. Time-over-threshold readout to enhance the high flux capabilities of single-photon-counting detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bergamaschi, Anna, E-mail: anna.bergamaschi@psi.ch; Dinapoli, Roberto; Greiffenberg, Dominic; Henrich, Beat; Johnson, Ian; Mozzanica, Aldo; Radicci, Valeria; Schmitt, Bernd; Shi, Xintian; Stoppani, Laura [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

    2011-11-01

    The MYTHEN photon-counting ASIC operated in time-over-threshold mode shows an innovative approach towards the development of a detector operating with very high photon intensities while maintaining the single-photon sensitivity for synchrotron radiation experiments. The MYTHEN single-photon-counting (SPC) detector has been characterized using the time-over-threshold (ToT) readout method, i.e. measuring the time that the signal produced by the detected X-rays remains above the comparator threshold. In the following it is shown that the ToT readout preserves the sensitivity, dynamic range and capability of background suppression of the SPC mode, while enhancing the count-rate capability, which is the main limitation of state-of-the-art SPC systems.

  15. Power distribution and substrate noise coupling investigations on the behavioral level for photon counting imaging readout circuits

    International Nuclear Information System (INIS)

    Lundgren, Jan; Abdalla, Suliman; O'Nils, Mattias; Oelmann, Bengt

    2007-01-01

    In modern mixed-signal system design, there are increasing problems associated with noise coupling caused by switching digital parts to sensitive analog parts. As a consequence, there is a growing necessity to understand these problems. In order to avoid costly design iterations, noise coupling simulations should be initiated as early as possible in the design chain. The problems associated with on-chip noise coupling have been discovered in photon counting pixel detector readout systems, where the level of integration of analog and digital circuits is very high on a very small area, and it would appear that these problems will continue to increase for future system designs in this field. This paper deals with the functionality of utilizing behavioral level models for simulating noise coupling in these readout systems. The methods and models are described and simulation results are shown for a photon counting pixel detector readout system

  16. Evaluation of mixed-signal noise effects in photon-counting X-ray image sensor readout circuits

    International Nuclear Information System (INIS)

    Lundgren, Jan; Abdalla, Suliman; O'Nils, Mattias; Oelmann, Bengt

    2006-01-01

    In readout electronics for photon-counting pixel detectors, the tight integration between analog and digital blocks causes the readout electronics to be sensitive to on-chip noise coupling. This noise coupling can result in faulty luminance values in grayscale X-ray images, or as color distortions in a color X-ray imaging system. An exploration of simulating noise coupling in readout circuits is presented which enables the discovery of sensitive blocks at as early a stage as possible, in order to avoid costly design iterations. The photon-counting readout system has been simulated for noise coupling in order to highlight the existing problems of noise coupling in X-ray imaging systems. The simulation results suggest that on-chip noise coupling should be considered and simulated in future readout electronics systems for X-ray detectors

  17. Spectral CT of the extremities with a silicon strip photon counting detector

    Science.gov (United States)

    Sisniega, A.; Zbijewski, W.; Stayman, J. W.; Xu, J.; Taguchi, K.; Siewerdsen, J. H.

    2015-03-01

    Purpose: Photon counting x-ray detectors (PCXDs) are an important emerging technology for spectral imaging and material differentiation with numerous potential applications in diagnostic imaging. We report development of a Si-strip PCXD system originally developed for mammography with potential application to spectral CT of musculoskeletal extremities, including challenges associated with sparse sampling, spectral calibration, and optimization for higher energy x-ray beams. Methods: A bench-top CT system was developed incorporating a Si-strip PCXD, fixed anode x-ray source, and rotational and translational motions to execute complex acquisition trajectories. Trajectories involving rotation and translation combined with iterative reconstruction were investigated, including single and multiple axial scans and longitudinal helical scans. The system was calibrated to provide accurate spectral separation in dual-energy three-material decomposition of soft-tissue, bone, and iodine. Image quality and decomposition accuracy were assessed in experiments using a phantom with pairs of bone and iodine inserts (3, 5, 15 and 20 mm) and an anthropomorphic wrist. Results: The designed trajectories improved the sampling distribution from 56% minimum sampling of voxels to 75%. Use of iterative reconstruction (viz., penalized likelihood with edge preserving regularization) in combination with such trajectories resulted in a very low level of artifacts in images of the wrist. For large bone or iodine inserts (>5 mm diameter), the error in the estimated material concentration was errors of 20-40% were observed and motivate improved methods for spectral calibration and optimization of the edge-preserving regularizer. Conclusion: Use of PCXDs for three-material decomposition in joint imaging proved feasible through a combination of rotation-translation acquisition trajectories and iterative reconstruction with optimized regularization.

  18. 8-Channel acquisition system for Time-Correlated Single-Photon Counting.

    Science.gov (United States)

    Antonioli, S; Miari, L; Cuccato, A; Crotti, M; Rech, I; Ghioni, M

    2013-06-01

    Nowadays, an increasing number of applications require high-performance analytical instruments capable to detect the temporal trend of weak and fast light signals with picosecond time resolution. The Time-Correlated Single-Photon Counting (TCSPC) technique is currently one of the preferable solutions when such critical optical signals have to be analyzed and it is fully exploited in biomedical and chemical research fields, as well as in security and space applications. Recent progress in the field of single-photon detector arrays is pushing research towards the development of high performance multichannel TCSPC systems, opening the way to modern time-resolved multi-dimensional optical analysis. In this paper we describe a new 8-channel high-performance TCSPC acquisition system, designed to be compact and versatile, to be used in modern TCSPC measurement setups. We designed a novel integrated circuit including a multichannel Time-to-Amplitude Converter with variable full-scale range, a D∕A converter, and a parallel adder stage. The latter is used to adapt each converter output to the input dynamic range of a commercial 8-channel Analog-to-Digital Converter, while the integrated DAC implements the dithering technique with as small as possible area occupation. The use of this monolithic circuit made the design of a scalable system of very small dimensions (95 × 40 mm) and low power consumption (6 W) possible. Data acquired from the TCSPC measurement are digitally processed and stored inside an FPGA (Field-Programmable Gate Array), while a USB transceiver allows real-time transmission of up to eight TCSPC histograms to a remote PC. Eventually, the experimental results demonstrate that the acquisition system performs TCSPC measurements with high conversion rate (up to 5 MHz/channel), extremely low differential nonlinearity (<0.04 peak-to-peak of the time bin width), high time resolution (down to 20 ps Full-Width Half-Maximum), and very low crosstalk between channels.

  19. Contrast-enhanced spectral mammography with a photon-counting detector.

    Science.gov (United States)

    Fredenberg, Erik; Hemmendorff, Magnus; Cederström, Björn; Aslund, Magnus; Danielsson, Mats

    2010-05-01

    Spectral imaging is a method in medical x-ray imaging to extract information about the object constituents by the material-specific energy dependence of x-ray attenuation. The authors have investigated a photon-counting spectral imaging system with two energy bins for contrast-enhanced mammography. System optimization and the potential benefit compared to conventional non-energy-resolved absorption imaging was studied. A framework for system characterization was set up that included quantum and anatomical noise and a theoretical model of the system was benchmarked to phantom measurements. Optimal combination of the energy-resolved images corresponded approximately to minimization of the anatomical noise, which is commonly referred to as energy subtraction. In that case, an ideal-observer detectability index could be improved close to 50% compared to absorption imaging in the phantom study. Optimization with respect to the signal-to-quantum-noise ratio, commonly referred to as energy weighting, yielded only a minute improvement. In a simulation of a clinically more realistic case, spectral imaging was predicted to perform approximately 30% better than absorption imaging for an average glandularity breast with an average level of anatomical noise. For dense breast tissue and a high level of anatomical noise, however, a rise in detectability by a factor of 6 was predicted. Another approximately 70%-90% improvement was found to be within reach for an optimized system. Contrast-enhanced spectral mammography is feasible and beneficial with the current system, and there is room for additional improvements. Inclusion of anatomical noise is essential for optimizing spectral imaging systems.

  20. Contrast-enhanced spectral mammography with a photon-counting detector

    Energy Technology Data Exchange (ETDEWEB)

    Fredenberg, Erik; Hemmendorff, Magnus; Cederstroem, Bjoern; Aaslund, Magnus; Danielsson, Mats [Department of Physics, Royal Institute of Technology, AlbaNova, SE-106 91 Stockholm (Sweden); Sectra Mamea AB, Smidesvaegen 5, SE-171 41 Solna (Sweden); Department of Physics, Royal Institute of Technology, AlbaNova, SE-106 91 Stockholm (Sweden); Sectra Mamea AB, Smidesvaegen 5, SE-171 41 Solna (Sweden); Department of Physics, Royal Institute of Technology, AlbaNova, SE-106 91 Stockholm (Sweden)

    2010-05-15

    Purpose: Spectral imaging is a method in medical x-ray imaging to extract information about the object constituents by the material-specific energy dependence of x-ray attenuation. The authors have investigated a photon-counting spectral imaging system with two energy bins for contrast-enhanced mammography. System optimization and the potential benefit compared to conventional non-energy-resolved absorption imaging was studied. Methods: A framework for system characterization was set up that included quantum and anatomical noise and a theoretical model of the system was benchmarked to phantom measurements. Results: Optimal combination of the energy-resolved images corresponded approximately to minimization of the anatomical noise, which is commonly referred to as energy subtraction. In that case, an ideal-observer detectability index could be improved close to 50% compared to absorption imaging in the phantom study. Optimization with respect to the signal-to-quantum-noise ratio, commonly referred to as energy weighting, yielded only a minute improvement. In a simulation of a clinically more realistic case, spectral imaging was predicted to perform approximately 30% better than absorption imaging for an average glandularity breast with an average level of anatomical noise. For dense breast tissue and a high level of anatomical noise, however, a rise in detectability by a factor of 6 was predicted. Another {approx}70%-90% improvement was found to be within reach for an optimized system. Conclusions: Contrast-enhanced spectral mammography is feasible and beneficial with the current system, and there is room for additional improvements. Inclusion of anatomical noise is essential for optimizing spectral imaging systems.

  1. Performance of in-pixel circuits for photon counting arrays (PCAs) based on polycrystalline silicon TFTs

    International Nuclear Information System (INIS)

    Liang, Albert K; Koniczek, Martin; Antonuk, Larry E; El-Mohri, Youcef; Zhao, Qihua; Street, Robert A; Lu, Jeng Ping

    2016-01-01

    Photon counting arrays (PCAs), defined as pixelated imagers which measure the absorbed energy of x-ray photons individually and record this information digitally, are of increasing clinical interest. A number of PCA prototypes with a 1 mm pixel-to-pixel pitch have recently been fabricated with polycrystalline silicon (poly-Si)—a thin-film technology capable of creating monolithic imagers of a size commensurate with human anatomy. In this study, analog and digital simulation frameworks were developed to provide insight into the influence of individual poly-Si transistors on pixel circuit performance—information that is not readily available through empirical means. The simulation frameworks were used to characterize the circuit designs employed in the prototypes. The analog framework, which determines the noise produced by individual transistors, was used to estimate energy resolution, as well as to identify which transistors contribute the most noise. The digital framework, which analyzes how well circuits function in the presence of significant variations in transistor properties, was used to estimate how fast a circuit can produce an output (referred to as output count rate). In addition, an algorithm was developed and used to estimate the minimum pixel pitch that could be achieved for the pixel circuits of the current prototypes. The simulation frameworks predict that the analog component of the PCA prototypes could have energy resolution as low as 8.9% full width at half maximum (FWHM) at 70 keV; and the digital components should work well even in the presence of significant thin-film transistor (TFT) variations, with the fastest component having output count rates as high as 3 MHz. Finally, based on conceivable improvements in the underlying fabrication process, the algorithm predicts that the 1 mm pitch of the current PCA prototypes could be reduced significantly, potentially to between ∼240 and 290 μm. (paper)

  2. Clinical experience of photon counting breast tomosynthesis: comparison with traditional mammography

    International Nuclear Information System (INIS)

    Svane, Gunilla; Azavedo, Edward; Lindman, Karin; Urech, Mattias; Nilsson, Jonas; Weber, Niclas; Lindqvist, Lars; Ullberg, Christer

    2011-01-01

    Background: In two-dimensional mammography, a well-known problem is over- and underlying tissue which can either obstruct a lesion or create a false-positive result. Tomosynthesis, with an ability to layer the tissue in the image, has the potential to resolve these issues. Purpose: To compare the diagnostic quality, sensitivity and specificity of a single tomosynthesis mammography image and a traditional two-view set of two-dimensional mammograms and to assess the comfort of the two techniques. Material and Methods: One hundred and forty-four women, mainly chosen because of suspicious features on standard mammograms (76 malignant), had a single tomosynthesis image taken of one breast using a novel photon counting system. On average, the dose of the tomosynthesis images was 0.63 times that of the two-view images and the compression force during the procedure was halved. The resulting images were viewed by two radiologists and assessed both individually and comparing the two techniques. Results: In 56% of the cases the radiologists rated the diagnostic quality of the lesion details higher in the tomosynthesis images than in the conventional images (and in 91% equal or higher), which means there is a statistically significant preference for the tomosynthesis technique. This included the calcifications which were rated as having better quality in 41% of the cases. While sensitivity was slightly higher for traditional mammography the specificity was higher for tomosynthesis. However, neither of these two differences was large enough to be statistically significant. Conclusion: The overall accuracy of the two techniques was virtually equal despite the radiologist's very limited experience with tomosynthesis images and vast experience with two-dimensional mammography. As the diagnostic quality of the lesion details in the tomosynthesis images was valued considerably higher this factor should improve with experience. The patients also favored the tomosynthesis examination

  3. A unified statistical framework for material decomposition using multienergy photon counting x-ray detectors

    International Nuclear Information System (INIS)

    Choi, Jiyoung; Kang, Dong-Goo; Kang, Sunghoon; Sung, Younghun; Ye, Jong Chul

    2013-01-01

    Purpose: Material decomposition using multienergy photon counting x-ray detectors (PCXD) has been an active research area over the past few years. Even with some success, the problem of optimal energy selection and three material decomposition including malignant tissue is still on going research topic, and more systematic studies are required. This paper aims to address this in a unified statistical framework in a mammographic environment.Methods: A unified statistical framework for energy level optimization and decomposition of three materials is proposed. In particular, an energy level optimization algorithm is derived using the theory of the minimum variance unbiased estimator, and an iterative algorithm is proposed for material composition as well as system parameter estimation under the unified statistical estimation framework. To verify the performance of the proposed algorithm, the authors performed simulation studies as well as real experiments using physical breast phantom and ex vivo breast specimen. Quantitative comparisons using various performance measures were conducted, and qualitative performance evaluations for ex vivo breast specimen were also performed by comparing the ground-truth malignant tissue areas identified by radiologists.Results: Both simulation and real experiments confirmed that the optimized energy bins by the proposed method allow better material decomposition quality. Moreover, for the specimen thickness estimation errors up to 2 mm, the proposed method provides good reconstruction results in both simulation and real ex vivo breast phantom experiments compared to existing methods.Conclusions: The proposed statistical framework of PCXD has been successfully applied for the energy optimization and decomposition of three material in a mammographic environment. Experimental results using the physical breast phantom and ex vivo specimen support the practicality of the proposed algorithm

  4. Renal stone characterization using high resolution imaging mode on a photon counting detector CT system

    Science.gov (United States)

    Ferrero, A.; Gutjahr, R.; Henning, A.; Kappler, S.; Halaweish, A.; Abdurakhimova, D.; Peterson, Z.; Montoya, J.; Leng, S.; McCollough, C.

    2017-03-01

    In addition to the standard-resolution (SR) acquisition mode, a high-resolution (HR) mode is available on a research photon-counting-detector (PCD) whole-body CT system. In the HR mode each detector consists of a 2x2 array of 0.225 mm x 0.225 mm subpixel elements. This is in contrast to the SR mode that consists of a 4x4 array of the same subelements, and results in 0.25 mm isotropic resolution at iso-center for the HR mode. In this study, we quantified ex vivo the capabilities of the HR mode to characterize renal stones in terms of morphology and mineral composition. Forty pure stones - 10 uric acid (UA), 10 cystine (CYS), 10 calcium oxalate monohydrate (COM) and 10 apatite (APA) - and 14 mixed stones were placed in a 20 cm water phantom and scanned in HR mode, at radiation dose matched to that of routine dual-energy stone exams. Data from micro CT provided a reference for the quantification of morphology and mineral composition of the mixed stones. The area under the ROC curve was 1.0 for discriminating UA from CYS, 0.89 for CYS vs COM and 0.84 for COM vs APA. The root mean square error (RMSE) of the percent UA in mixed stones was 11.0% with a medium-sharp kernel and 15.6% with the sharpest kernel. The HR showed qualitatively accurate characterization of stone morphology relative to micro CT.

  5. Energy-correction photon counting pixel for photon energy extraction under pulse pile-up

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Daehee; Park, Kyungjin; Lim, Kyung Taek; Cho, Gyuseong, E-mail: gscho@kaist.ac.kr

    2017-06-01

    A photon counting detector (PCD) has been proposed as an alternative solution to an energy-integrating detector (EID) in medical imaging field due to its high resolution, high efficiency, and low noise. The PCD has expanded to variety of fields such as spectral CT, k-edge imaging, and material decomposition owing to its capability to count and measure the number and the energy of an incident photon, respectively. Nonetheless, pulse pile-up, which is a superimposition of pulses at the output of a charge sensitive amplifier (CSA) in each PC pixel, occurs frequently as the X-ray flux increases due to the finite pulse processing time (PPT) in CSAs. Pulse pile-up induces not only a count loss but also distortion in the measured X-ray spectrum from each PC pixel and thus it is a main constraint on the use of PCDs in high flux X-ray applications. To minimize these effects, an energy-correction PC (ECPC) pixel is proposed to resolve pulse pile-up without cutting off the PPT by adding an energy correction logic (ECL) via a cross detection method (CDM). The ECPC pixel with a size of 200×200 µm{sup 2} was fabricated by using a 6-metal 1-poly 0.18 µm CMOS process with a static power consumption of 7.2 μW/pixel. The maximum count rate of the ECPC pixel was extended by approximately three times higher than that of a conventional PC pixel with a PPT of 500 nsec. The X-ray spectrum of 90 kVp, filtered by 3 mm Al filter, was measured as the X-ray current was increased using the CdTe and the ECPC pixel. As a result, the ECPC pixel dramatically reduced the energy spectrum distortion at 2 Mphotons/pixel/s when compared to that of the ERCP pixel with the same 500 nsec PPT.

  6. Initial steps toward the realization of large area arrays of single photon counting pixels based on polycrystalline silicon TFTs

    Science.gov (United States)

    Liang, Albert K.; Koniczek, Martin; Antonuk, Larry E.; El-Mohri, Youcef; Zhao, Qihua; Jiang, Hao; Street, Robert A.; Lu, Jeng Ping

    2014-03-01

    The thin-film semiconductor processing methods that enabled creation of inexpensive liquid crystal displays based on amorphous silicon transistors for cell phones and televisions, as well as desktop, laptop and mobile computers, also facilitated the development of devices that have become ubiquitous in medical x-ray imaging environments. These devices, called active matrix flat-panel imagers (AMFPIs), measure the integrated signal generated by incident X rays and offer detection areas as large as ~43×43 cm2. In recent years, there has been growing interest in medical x-ray imagers that record information from X ray photons on an individual basis. However, such photon counting devices have generally been based on crystalline silicon, a material not inherently suited to the cost-effective manufacture of monolithic devices of a size comparable to that of AMFPIs. Motivated by these considerations, we have developed an initial set of small area prototype arrays using thin-film processing methods and polycrystalline silicon transistors. These prototypes were developed in the spirit of exploring the possibility of creating large area arrays offering single photon counting capabilities and, to our knowledge, are the first photon counting arrays fabricated using thin film techniques. In this paper, the architecture of the prototype pixels is presented and considerations that influenced the design of the pixel circuits, including amplifier noise, TFT performance variations, and minimum feature size, are discussed.

  7. Evaluation of the charge-sharing effects on spot intensity in XRD setup using photon-counting pixel detectors

    International Nuclear Information System (INIS)

    Nilsson, H.-E.; Mattsson, C.G.; Norlin, B.; Froejdh, C.; Bethke, K.; Vries, R. de

    2006-01-01

    In this study, we examine how charge loss due to charge sharing in photon-counting pixels detectors affects the recording of spot intensity in an X-ray diffraction (XRD) setup. In the photon-counting configuration, the charge from photons that are absorbed at the boarder of a pixel will be shared between two pixels. If the threshold is high enough, these photons will not be counted whereas if it is low enough, they will be counted twice. In an XRD setup, the intensity and position of various spots should be recorded. Thus, the intensity measure will be affected by the setting of the threshold. In this study, we used a system level Monte Carlo simulator to evaluate the variations in the intensity signals for different threshold settings and spot sizes. The simulated setup included an 8keV mono-chromatic source (providing a Gaussian shaped spot) and the MEDIPIX2 photon-counting pixel detector (55 μm x 55 μm pixel size with 300μm silicon) at various detector biases. Our study shows that the charge-sharing distortion can be compensated by numerical post processing and that high resolution in both charge distribution and position can be achieved

  8. Direct measurement of radioactive carbon in Vietnamese vodkas by Liquid Scintillation Counter

    International Nuclear Information System (INIS)

    Hattori, Takamitsu

    2014-01-01

    From the view point of applying to laboratory exercise of radioactivity measurement by a Liquid Scintillation Counter (LSC), Vietnamese vodkas have specific features as measurement samples, for example, they are colorless, have high ethanol content, and only very few organic materials are included. Investigation was made to make sure that the Vietnamese vodkas are appropriate or not as a measurement sample for the LSC exercise. Direct measurements of 14 C without any chemical pre-treatment were made on both radioactive concentrations and specific activities of three kinds of Vietnamese vodka and also pure ethanol reagent. The LSC measurements reveal that estimated 14 C concentration is proportional to ethanol content in samples and that specific activity of 14 C shows good agreement among the Vietnamese vodkas and pure ethanol, as well as the reference value of 0.25 Bq/g of Carbon. Thus the conclusion is derived that the Vietnamese vodkas can be applied with high accuracy to the LSC exercise as measurement samples. (author)

  9. Seeing the invisible: direct visualization of therapeutic radiation beams using air scintillation.

    Science.gov (United States)

    Fahimian, Benjamin; Ceballos, Andrew; Türkcan, Silvan; Kapp, Daniel S; Pratx, Guillem

    2014-01-01

    To assess whether air scintillation produced during standard radiation treatments can be visualized and used to monitor a beam in a nonperturbing manner. Air scintillation is caused by the excitation of nitrogen gas by ionizing radiation. This weak emission occurs predominantly in the 300-430 nm range. An electron-multiplication charge-coupled device camera, outfitted with an f/0.95 lens, was used to capture air scintillation produced by kilovoltage photon beams and megavoltage electron beams used in radiation therapy. The treatment rooms were prepared to block background light and a short-pass filter was utilized to block light above 440 nm. Air scintillation from an orthovoltage unit (50 kVp, 30 mA) was visualized with a relatively short exposure time (10 s) and showed an inverse falloff (r(2) = 0.89). Electron beams were also imaged. For a fixed exposure time (100 s), air scintillation was proportional to dose rate (r(2) = 0.9998). As energy increased, the divergence of the electron beam decreased and the penumbra improved. By irradiating a transparent phantom, the authors also showed that Cherenkov luminescence did not interfere with the detection of air scintillation. In a final illustration of the capabilities of this new technique, the authors visualized air scintillation produced during a total skin irradiation treatment. Air scintillation can be measured to monitor a radiation beam in an inexpensive and nonperturbing manner. This physical phenomenon could be useful for dosimetry of therapeutic radiation beams or for online detection of gross errors during fractionated treatments.

  10. Seeing the invisible: Direct visualization of therapeutic radiation beams using air scintillation

    Energy Technology Data Exchange (ETDEWEB)

    Fahimian, Benjamin; Türkcan, Silvan; Kapp, Daniel S.; Pratx, Guillem, E-mail: pratx@stanford.edu [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305 (United States); Ceballos, Andrew [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

    2014-01-15

    Purpose: To assess whether air scintillation produced during standard radiation treatments can be visualized and used to monitor a beam in a nonperturbing manner. Methods: Air scintillation is caused by the excitation of nitrogen gas by ionizing radiation. This weak emission occurs predominantly in the 300–430 nm range. An electron-multiplication charge-coupled device camera, outfitted with an f/0.95 lens, was used to capture air scintillation produced by kilovoltage photon beams and megavoltage electron beams used in radiation therapy. The treatment rooms were prepared to block background light and a short-pass filter was utilized to block light above 440 nm. Results: Air scintillation from an orthovoltage unit (50 kVp, 30 mA) was visualized with a relatively short exposure time (10 s) and showed an inverse falloff (r{sup 2} = 0.89). Electron beams were also imaged. For a fixed exposure time (100 s), air scintillation was proportional to dose rate (r{sup 2} = 0.9998). As energy increased, the divergence of the electron beam decreased and the penumbra improved. By irradiating a transparent phantom, the authors also showed that Cherenkov luminescence did not interfere with the detection of air scintillation. In a final illustration of the capabilities of this new technique, the authors visualized air scintillation produced during a total skin irradiation treatment. Conclusions: Air scintillation can be measured to monitor a radiation beam in an inexpensive and nonperturbing manner. This physical phenomenon could be useful for dosimetry of therapeutic radiation beams or for online detection of gross errors during fractionated treatments.

  11. Spectral and spatial resolution properties of photon counting X-ray detectors like the Medipix-Detector

    International Nuclear Information System (INIS)

    Korn, A.

    2007-01-01

    The Medipix detector is a hybrid photon counting X-ray detector, consisting of an ASIC and a semiconducting layer as the sensor. This makes the Medipix a direct converting detector. A special feature of the Medipix is a signal processing circuit in every single pixel. This circuit amplifies the input signal triggered by a photon and then transforms the pulse into a digital signal. This early stage digitalisation is one of the main advantages of the detector, since no dark currents are integrated into the signal. Furthermore, the energy information of each single photon is partly preserved. The high number of pixels lends the detector a wide dynamic range, starting from single counts up to a rate of 1010 photons per cm2 and second. Apart from the many advantages, there are still some problems with the detector. Some effects lead to a deterioration of the energy resolution as well as the spatial resolution. The main reasons for this are two effects occuring in the detector, charge sharing and backscattering inside the detector. This study investigates the influence of those two effects on both the energy and spatial resolution. The physical causes of these effects are delineated and their impact on the detector output is examined. In contrast to high energy photon detectors, the repulsion of the charge carriers drifting inside the sensor must not be neglected in a detailed model of X-ray detectors with an energy range of 5 keV-200 keV. For the simulation of the Medipix using Monte Carlo simulations, the software ROSI was augmented. The added features allow a detailed simulation of the charge distribution, using the relevant physical effects that alter the distribution width during the drift towards the sensor electrodes as well further influences on the detector output, including electronical noise, threshold noise or the geometry of the detector. The measured energy and spatial resolution of several different models of Medipix is compared to the simulated

  12. Quantitative contrast-enhanced spectral mammography based on photon-counting detectors: A feasibility study.

    Science.gov (United States)

    Ding, Huanjun; Molloi, Sabee

    2017-08-01

    To investigate the feasibility of accurate quantification of iodine mass thickness in contrast-enhanced spectral mammography. A computer simulation model was developed to evaluate the performance of a photon-counting spectral mammography system in the application of contrast-enhanced spectral mammography. A figure-of-merit (FOM), which was defined as the decomposed iodine signal-to-noise ratio (SNR) with respect to the square root of the mean glandular dose (MGD), was chosen to optimize the imaging parameters, in terms of beam energy, splitting energy, and prefiltrations for breasts of various thicknesses and densities. Experimental phantom studies were also performed using a beam energy of 40 kVp and a splitting energy of 34 keV with 3 mm Al prefiltration. A two-step calibration method was investigated to quantify the iodine mass thickness, and was validated using phantoms composed of a mixture of glandular and adipose materials, for various breast thicknesses and densities. Finally, the traditional dual-energy log-weighted subtraction method was also studied as a comparison. The measured iodine signal from both methods was compared to the known value to characterize the quantification accuracy and precision. The optimal imaging parameters, which lead to the highest FOM, were found at a beam energy between 42 and 46 kVp with a splitting energy at 34 keV. The optimal tube voltage decreased as the breast thickness or the Al prefiltration increased. The proposed quantification method was able to measure iodine mass thickness on phantoms of various thicknesses and densities with high accuracy. The root-mean-square (RMS) error for cm-scale lesion phantoms was estimated to be 0.20 mg/cm 2 . The precision of the technique, characterized by the standard deviation of the measurements, was estimated to be 0.18 mg/cm 2 . The traditional weighted subtraction method also predicted a linear correlation between the measured signal and the known iodine mass thickness. However

  13. EIGER: Next generation single photon counting detector for X-ray applications

    Energy Technology Data Exchange (ETDEWEB)

    Dinapoli, Roberto, E-mail: roberto.dinapoli@psi.ch [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Bergamaschi, Anna; Henrich, Beat; Horisberger, Roland; Johnson, Ian; Mozzanica, Aldo; Schmid, Elmar; Schmitt, Bernd; Schreiber, Akos; Shi, Xintian; Theidel, Gerd [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland)

    2011-09-11

    EIGER is an advanced family of single photon counting hybrid pixel detectors, primarily aimed at diffraction experiments at synchrotrons. Optimization of maximal functionality and minimal pixel size (using a 0.25{mu}m process and conserving the radiation tolerant design) has resulted in 75x75{mu}m{sup 2} pixels. Every pixel comprises a preamplifier, shaper, discriminator (with a 6 bit DAC for threshold trimming), a configurable 4/8/12 bit counter with double buffering, as well as readout, control and test circuitry. A novel feature of this chip is its double buffered counter, meaning a next frame can be acquired while the previous one is being readout. An array of 256x256 pixels fits on a {approx}2x2cm{sup 2} chip and a sensor of {approx}8x4cm{sup 2} will be equipped with eight readout chips to form a module containing 0.5 Mpixel. Several modules can then be tiled to form larger area detectors. Detectors up to 4x8 modules (16 Mpixel) are planned. To achieve frame rates of up to 24 kHz the readout architecture is highly parallel, and the chip readout happens in parallel on 32 readout lines with a 100 MHz Double Data Rate clock. Several chips and singles (i.e. a single chip bump-bonded to a single chip silicon sensor) were tested both with a lab X-ray source and at Swiss Light Source (SLS) beamlines. These tests demonstrate the full functionality of the chip and provide a first assessment of its performance. High resolution X-ray images and 'high speed movies' were produced, even without threshold trimming, at the target system frame rates (up to {approx}24kHz in 4 bit mode). In parallel, dedicated hardware, firmware and software had to be developed to comply with the enormous data rate the chip is capable of delivering. Details of the chip design and tests will be given, as well as highlights of both test and final readout systems.

  14. 18k Channels single photon counting readout circuit for hybrid pixel detector

    International Nuclear Information System (INIS)

    Maj, P.; Grybos, P.; Szczygiel, R.; Zoladz, M.; Sakumura, T.; Tsuji, Y.

    2013-01-01

    We have performed measurements of an integrated circuit named PXD18k designed for hybrid pixel semiconductor detectors used in X-ray imaging applications. The PXD18k integrated circuit, fabricated in CMOS 180 nm technology, has dimensions of 9.64 mm×20 mm and contains approximately 26 million transistors. The core of the IC is a matrix of 96×192 pixels with 100 μm×100 μm pixel size. Each pixel works in a single photon counting mode. A single pixel contains two charge sensitive amplifiers with Krummenacher feedback scheme, two shapers, two discriminators (with independent thresholds A and B) and two 16-bit ripple counters. The data are read out via eight low voltage differential signaling (LVDS) outputs with 100 Mbps rate. The power consumption is dominated by analog blocks and it is about 23 μW/pixel. The effective peaking time at the discriminator input is 30 ns and is mainly determined by the time constants of the charge sensitive amplifier (CSA). The gain is equal to 42.5 μV/e − and the equivalent noise charge is 168 e − rms (with bump-bonded silicon pixel detector). Thanks to the use of trim DACs in each pixel, the effective threshold spread at the discriminator input is only 1.79 mV. The dead time of the front end electronics for a standard setting is 172 ns (paralyzable model). In the standard readout mode (when the data collection time is separated from the time necessary to readout data from the chip) the PXD18k IC works with two energy thresholds per pixel. The PXD18k can also be operated in the continuous readout mode (with a zero dead time) where one can select the number of bits readout from each pixel to optimize the PXD18k frame rate. For example, for reading out 16 bits/pixel the frame rate is 2.7 kHz and for 4 bits/pixel it rises to 7.1 kHz.

  15. 18k Channels single photon counting readout circuit for hybrid pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Maj, P., E-mail: piotr.maj@agh.edu.pl [AGH University of Science and Technology, Department of Measurements and Electronics, Al. Mickiewicza 30, 30-059 Krakow (Poland); Grybos, P.; Szczygiel, R.; Zoladz, M. [AGH University of Science and Technology, Department of Measurements and Electronics, Al. Mickiewicza 30, 30-059 Krakow (Poland); Sakumura, T.; Tsuji, Y. [X-ray Analysis Division, Rigaku Corporation, Matsubara, Akishima, Tokyo 196-8666 (Japan)

    2013-01-01

    We have performed measurements of an integrated circuit named PXD18k designed for hybrid pixel semiconductor detectors used in X-ray imaging applications. The PXD18k integrated circuit, fabricated in CMOS 180 nm technology, has dimensions of 9.64 mm Multiplication-Sign 20 mm and contains approximately 26 million transistors. The core of the IC is a matrix of 96 Multiplication-Sign 192 pixels with 100 {mu}m Multiplication-Sign 100 {mu}m pixel size. Each pixel works in a single photon counting mode. A single pixel contains two charge sensitive amplifiers with Krummenacher feedback scheme, two shapers, two discriminators (with independent thresholds A and B) and two 16-bit ripple counters. The data are read out via eight low voltage differential signaling (LVDS) outputs with 100 Mbps rate. The power consumption is dominated by analog blocks and it is about 23 {mu}W/pixel. The effective peaking time at the discriminator input is 30 ns and is mainly determined by the time constants of the charge sensitive amplifier (CSA). The gain is equal to 42.5 {mu}V/e{sup -} and the equivalent noise charge is 168 e{sup -} rms (with bump-bonded silicon pixel detector). Thanks to the use of trim DACs in each pixel, the effective threshold spread at the discriminator input is only 1.79 mV. The dead time of the front end electronics for a standard setting is 172 ns (paralyzable model). In the standard readout mode (when the data collection time is separated from the time necessary to readout data from the chip) the PXD18k IC works with two energy thresholds per pixel. The PXD18k can also be operated in the continuous readout mode (with a zero dead time) where one can select the number of bits readout from each pixel to optimize the PXD18k frame rate. For example, for reading out 16 bits/pixel the frame rate is 2.7 kHz and for 4 bits/pixel it rises to 7.1 kHz.

  16. Advanced Photon Counting Imaging Detectors with 100ps Timing for Astronomical and Space Sensing Applications

    Science.gov (United States)

    Siegmund, O.; Vallerga, J.; Welsh, B.; Rabin, M.; Bloch, J.

    In recent years EAG has implemented a variety of high-resolution, large format, photon-counting MCP detectors in space instrumentation for satellite FUSE, GALEX, IMAGE, SOHO, HST-COS, rocket, and shuttle payloads. Our scheme of choice has been delay line readouts encoding photon event position centroids, by determination of the difference in arrival time of the event charge at the two ends of a distributed resistive-capacitive (RC) delay line. Our most commonly used delay line configuration is the cross delay line (XDL). In its simplest form the delay-line encoding electronics consists of a fast amplifier for each end of the delay line, followed by time-to-digital converters (TDC's). We have achieved resolutions of Pulsar with a telescope as small as 1m. Although microchannel plate delay line detectors meet many of the imaging and timing demands of various applications, they have limitations. The relatively high gain (107) reduces lifetime and local counting rate, and the fixed delay (10's of ns) makes multiple simultaneous event recording problematic. To overcome these limitations we have begun development of cross strip readout anodes for microchannel plate detectors. The cross strip (XS) anode is a coarse (~0.5 mm) multi-layer metal and ceramic pattern of crossed fingers on an alumina substrate. The charge cloud is matched to the anode period so that it is collected on several neighboring fingers to ensure an accurate event charge centroid can be determined. Each finger of the anode is connected to a low noise charge sensitive amplifier and followed by subsequent A/D conversion of individual strip charge values and a hardware centroid determination of better than 1/100 of a strip are possible. Recently we have commissioned a full 32 x 32 mm XS open face laboratory detector and demonstrated excellent resolution (Los Alamos National Laboratory, NASA and NSF we are developing high rate (>107 Hz) XS encoding electronics that will encode temporally simultaneous

  17. Microcalcification detectability using a bench-top prototype photon-counting breast CT based on a Si strip detector.

    Science.gov (United States)

    Cho, Hyo-Min; Ding, Huanjun; Barber, William C; Iwanczyk, Jan S; Molloi, Sabee

    2015-07-01

    To investigate the feasibility of detecting breast microcalcification (μCa) with a dedicated breast computed tomography (CT) system based on energy-resolved photon-counting silicon (Si) strip detectors. The proposed photon-counting breast CT system and a bench-top prototype photon-counting breast CT system were simulated using a simulation package written in matlab to determine the smallest detectable μCa. A 14 cm diameter cylindrical phantom made of breast tissue with 20% glandularity was used to simulate an average-sized breast. Five different size groups of calcium carbonate grains, from 100 to 180 μm in diameter, were simulated inside of the cylindrical phantom. The images were acquired with a mean glandular dose (MGD) in the range of 0.7-8 mGy. A total of 400 images was used to perform a reader study. Another simulation study was performed using a 1.6 cm diameter cylindrical phantom to validate the experimental results from a bench-top prototype breast CT system. In the experimental study, a bench-top prototype CT system was constructed using a tungsten anode x-ray source and a single line 256-pixels Si strip photon-counting detector with a pixel pitch of 100 μm. Calcium carbonate grains, with diameter in the range of 105-215 μm, were embedded in a cylindrical plastic resin phantom to simulate μCas. The physical phantoms were imaged at 65 kVp with an entrance exposure in the range of 0.6-8 mGy. A total of 500 images was used to perform another reader study. The images were displayed in random order to three blinded observers, who were asked to give a 4-point confidence rating on each image regarding the presence of μCa. The μCa detectability for each image was evaluated by using the average area under the receiver operating characteristic curve (AUC) across the readers. The simulation results using a 14 cm diameter breast phantom showed that the proposed photon-counting breast CT system can achieve high detection accuracy with an average AUC greater

  18. Evaluation of conventional imaging performance in a research whole-body CT system with a photon-counting detector array

    International Nuclear Information System (INIS)

    Yu, Zhicong; Leng, Shuai; Li, Zhoubo; Chen, Baiyu; Yu, Lifeng; McCollough, Cynthia H; Jorgensen, Steven M; Ritman, Erik L; Gutjahr, Ralf; Kappler, Steffen; Halaweish, Ahmed F

    2016-01-01

    This study evaluated the conventional imaging performance of a research whole-body photon-counting CT system and investigated its feasibility for imaging using clinically realistic levels of x-ray photon flux. This research system was built on the platform of a 2nd generation dual-source CT system: one source coupled to an energy integrating detector (EID) and the other coupled to a photon-counting detector (PCD). Phantom studies were conducted to measure CT number accuracy and uniformity for water, CT number energy dependency for high-Z materials, spatial resolution, noise, and contrast-to-noise ratio. The results from the EID and PCD subsystems were compared. The impact of high photon flux, such as pulse pile-up, was assessed by studying the noise-to-tube-current relationship using a neonate water phantom and high x-ray photon flux. Finally, clinical feasibility of the PCD subsystem was investigated using anthropomorphic phantoms, a cadaveric head, and a whole-body cadaver, which were scanned at dose levels equivalent to or higher than those used clinically. Phantom measurements demonstrated that the PCD subsystem provided comparable image quality to the EID subsystem, except that the PCD subsystem provided slightly better longitudinal spatial resolution and about 25% improvement in contrast-to-noise ratio for iodine. The impact of high photon flux was found to be negligible for the PCD subsystem: only subtle high-flux effects were noticed for tube currents higher than 300 mA in images of the neonate water phantom. Results of the anthropomorphic phantom and cadaver scans demonstrated comparable image quality between the EID and PCD subsystems. There were no noticeable ring, streaking, or cupping/capping artifacts in the PCD images. In addition, the PCD subsystem provided spectral information. Our experiments demonstrated that the research whole-body photon-counting CT system is capable of providing clinical image quality at clinically realistic levels of x

  19. Evaluation of conventional imaging performance in a research whole-body CT system with a photon-counting detector array.

    Science.gov (United States)

    Yu, Zhicong; Leng, Shuai; Jorgensen, Steven M; Li, Zhoubo; Gutjahr, Ralf; Chen, Baiyu; Halaweish, Ahmed F; Kappler, Steffen; Yu, Lifeng; Ritman, Erik L; McCollough, Cynthia H

    2016-02-21

    This study evaluated the conventional imaging performance of a research whole-body photon-counting CT system and investigated its feasibility for imaging using clinically realistic levels of x-ray photon flux. This research system was built on the platform of a 2nd generation dual-source CT system: one source coupled to an energy integrating detector (EID) and the other coupled to a photon-counting detector (PCD). Phantom studies were conducted to measure CT number accuracy and uniformity for water, CT number energy dependency for high-Z materials, spatial resolution, noise, and contrast-to-noise ratio. The results from the EID and PCD subsystems were compared. The impact of high photon flux, such as pulse pile-up, was assessed by studying the noise-to-tube-current relationship using a neonate water phantom and high x-ray photon flux. Finally, clinical feasibility of the PCD subsystem was investigated using anthropomorphic phantoms, a cadaveric head, and a whole-body cadaver, which were scanned at dose levels equivalent to or higher than those used clinically. Phantom measurements demonstrated that the PCD subsystem provided comparable image quality to the EID subsystem, except that the PCD subsystem provided slightly better longitudinal spatial resolution and about 25% improvement in contrast-to-noise ratio for iodine. The impact of high photon flux was found to be negligible for the PCD subsystem: only subtle high-flux effects were noticed for tube currents higher than 300 mA in images of the neonate water phantom. Results of the anthropomorphic phantom and cadaver scans demonstrated comparable image quality between the EID and PCD subsystems. There were no noticeable ring, streaking, or cupping/capping artifacts in the PCD images. In addition, the PCD subsystem provided spectral information. Our experiments demonstrated that the research whole-body photon-counting CT system is capable of providing clinical image quality at clinically realistic levels of x

  20. Photon-Counting Kinetic Inductance Detectors (KID) for Far/Mid-Infrared Space Spectroscopy with the Origins Space Telescope (OST)

    Science.gov (United States)

    Noroozian, Omid; Barrentine, Emily M.; Stevenson, Thomas R.; Brown, Ari D.; Moseley, Samuel Harvey; Wollack, Edward; Pontoppidan, Klaus Martin; U-Yen, Konpop; Mikula, Vilem

    2018-01-01

    Photon-counting detectors are highly desirable for reaching the ~ 10-20 W/√Hz power sensitivity permitted by the Origins Space Telescope (OST). We are developing unique Kinetic Inductance Detectors (KIDs) with photon counting capability in the far/mid-IR. Combined with an on-chip far-IR spectrometer onboard OST these detectors will enable a new data set for exploring galaxy evolution and the growth of structure in the Universe. Mid-IR spectroscopic surveys using these detectors will enable mapping the composition of key volatiles in planet-forming material around protoplanetary disks and their evolution into solar systems. While these OST science objectives represent a well-organized community agreement they are impossible to reach without a significant leap forward in detector technology, and the OST is likely not to be recommended if a path to suitable detectors does not exist.To reach the required sensitivity we are experimenting with superconducting resonators made from thin aluminum films on single-crystal silicon substrates. Under the right conditions, small-volume inductors made from these films can become ultra-sensitive to single photons >90 GHz. Understanding the physics of these superconductor-dielectric systems is critical to performance. We achieved a very high quality factor of 0.5 x 106 for a 10-nm Al resonator at n ~ 1 microwave photon drive power, by far the highest value for such thin films in the literature. We measured a residual electron density of detector when illuminated with randomly arriving photon events. Our results show that photon counting with >95% efficiency at 0.5 - 1.0 THz is achievable.We report on these developments and discuss plans to test in our facility through funding from our recently awarded ROSES-APRA grant and Roman Technology Fellowship award.

  1. WE-DE-207B-01: Optimization for Contrast-Enhanced Spectral Mammography Based On Photon-Counting Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Ding, H; Molloi, S [University of California, Irvine, CA (United States)

    2016-06-15

    Purpose: To investigate the feasibility of optimizing the imaging parameters for contrast-enhanced spectral mammography based on Si strip photon-counting detectors. Methods: A computer simulation model using polyenergetic spectra from a tungsten anode x-ray tube and a Si-based photon-counting detector was evaluated for contrast-enhanced spectral mammography. The simulation traces the emission of photons from the x-ray source, attenuation through the breast and subsequent absorption in the detector. The breast was modeled as a mixture of adipose and mammary gland tissues with a breast density of 30%. A 4 mm iodine signal with a concentration of 4 mg/ml was used to simulate the enhancement of a lesion. Quantum efficiency of the detector was calculated based on the effective attenuation length in the Si strips. The figure-of-merit (FOM), which was defined as the decomposed iodine signal-to-noise ratio (SNR) with respect to the square root of the mean glandular dose (MGD), was chosen to optimize the imaging parameters, in terms of beam energy, splitting energy, and pre-filtrations for breast of various thicknesses and densities. Results: The optimal imaging parameters, which lead to the highest FOM, were found at a beam energy of 45 kVp with a splitting energy at 34 keV for an averaged breast thickness of 4 cm with a standard 0.75 mm Al pre-filtration. The optimal tube voltage varied slightly from 46 to 44 kVp as the breast thickness increases from 2 to 8 cm. The optimal tube voltage decreased to 42 kVp when the Al pre-filtration was increased to 3 mm. Conclusion: This simulation study predicted the optimal imaging parameters for application of photon-counting spectral mammography to contrast-enhanced imaging. The simulation results laid the ground work for future phantom and clinical studies. Grant funding from Philips Medical Systems.

  2. Front-illuminated versus back-illuminated photon-counting CCD-based gamma camera: important consequences for spatial resolution and energy resolution

    International Nuclear Information System (INIS)

    Heemskerk, Jan W T; Westra, Albert H; Linotte, Peter M; Ligtvoet, Kees M; Zbijewski, Wojciech; Beekman, Freek J

    2007-01-01

    Charge-coupled devices (CCDs) coupled to scintillation crystals can be used for high-resolution imaging with x-rays and gamma rays. When the CCD images can be read out fast enough, the energy and interaction position of individual gamma quanta can be estimated by a real-time image analysis of the scintillation light flashes ('photon-counting mode'). The electron-multiplying CCD (EMCCD) is well suited for fast read out, since even at high frame rates it has extremely low read-out noise. Back-illuminated (BI) EMCCDs have much higher quantum efficiency than front-illuminated (FI) EMCCDs. Here we compare the spatial and energy resolution of gamma cameras based on FI and BI EMCCDs. The CCDs are coupled to a 1000 μm thick columnar CsI(Tl) crystal for the purpose of Tc-99m and I-125 imaging. Intrinsic spatial resolutions of 44 μm for I-125 and 49 μm for Tc-99m were obtained when using a BI EMCCD, which is an improvement by a factor of about 1.2-2 over the FI EMCCD. Furthermore, in the energy spectrum of the BI EMCCD, the I-125 signal could be clearly separated from the background noise, which was not the case for the FI EMCCD. The energy resolution of a BI EMCCD for Tc-99m was estimated to be approximately 36 keV, full width at half maximum, at 141 keV. The excellent results for the BI EMCCD encouraged us to investigate the cooling requirements for our setup. We have found that for the BI EMCCD, the spatial and energy resolution, as well as image noise, remained stable over a range of temperatures from -50 deg. C to -15 deg. C. This is a significant advantage over the FI EMCCD, which suffered from loss of spatial and especially energy resolution at temperatures as low as -40 deg. C. We conclude that the use of BI EMCCDs may significantly improve the imaging capabilities and the cost efficiency of CCD-based high-resolution gamma cameras. (note)

  3. Mode-Selective Photon Counting Via Quantum Frequency Conversion Using Spectrally-Engineered Pump Pulses

    Science.gov (United States)

    Manurkar, Paritosh

    phase of each spectral frequency from an optical frequency comb. The latter is generated using a cascaded configuration of phase and amplitude modulators. We characterize the mode selectivity using classical signals by arranging the six TMs into two orthogonal signal sets. Furthermore, we also demonstrate that mode selectivity is preserved if we use sub-photon signals (weak coherent light). Thus, this work supports the idea that QFC has the basic properties needed for advanced multi-dimensional quantum measurements given that we have demonstrated for the first time the ability to move to high dimensions (d=4), measure coherent superposition modes, and measure sub-photon signal levels. In addition to mode-selective photon counting, we also experimentally demonstrate a method of reshaping optical pulses based on QFC. Such a method has the potential to serve as the interface between quantum memories and the existing fiber infrastructure. At the same time, it can be employed in all-optical systems for optical signal regeneration.

  4. Spatio-energetic cross talk in photon counting detectors: Detector model and correlated Poisson data generator.

    Science.gov (United States)

    Taguchi, Katsuyuki; Polster, Christoph; Lee, Okkyun; Stierstorfer, Karl; Kappler, Steffen

    2016-12-01

    An x-ray photon interacts with photon counting detectors (PCDs) and generates an electron charge cloud or multiple clouds. The clouds (thus, the photon energy) may be split between two adjacent PCD pixels when the interaction occurs near pixel boundaries, producing a count at both of the pixels. This is called double-counting with charge sharing. (A photoelectric effect with K-shell fluorescence x-ray emission would result in double-counting as well). As a result, PCD data are spatially and energetically correlated, although the output of individual PCD pixels is Poisson distributed. Major problems include the lack of a detector noise model for the spatio-energetic cross talk and lack of a computationally efficient simulation tool for generating correlated Poisson data. A Monte Carlo (MC) simulation can accurately simulate these phenomena and produce noisy data; however, it is not computationally efficient. In this study, the authors developed a new detector model and implemented it in an efficient software simulator that uses a Poisson random number generator to produce correlated noisy integer counts. The detector model takes the following effects into account: (1) detection efficiency; (2) incomplete charge collection and ballistic effect; (3) interaction with PCDs via photoelectric effect (with or without K-shell fluorescence x-ray emission, which may escape from the PCDs or be reabsorbed); and (4) electronic noise. The correlation was modeled by using these two simplifying assumptions: energy conservation and mutual exclusiveness. The mutual exclusiveness is that no more than two pixels measure energy from one photon. The effect of model parameters has been studied and results were compared with MC simulations. The agreement, with respect to the spectrum, was evaluated using the reduced χ 2 statistics or a weighted sum of squared errors, χ red 2 (≥1), where χ red 2 =1 indicates a perfect fit. The model produced spectra with flat field irradiation that

  5. Cascaded systems analysis of charge sharing in cadmium telluride photon-counting x-ray detectors.

    Science.gov (United States)

    Tanguay, Jesse; Cunningham, Ian A

    2018-05-01

    Single-photon-counting (SPC) and spectroscopic x-ray detectors are under development in academic and industry laboratories for medical imaging applications. The spatial resolution of SPC and spectroscopic x-ray detectors is an important design criterion. The purpose of this article was to extend the cascaded systems approach to include a description of the spatial resolution of SPC and spectroscopic x-ray imaging detectors. A cascaded systems approach was used to model reabsorption of characteristic x rays, Coulomb repulsion, and diffusion in SPC and spectroscopic x-ray detectors. In addition to reabsorption, diffusion, and Coulomb repulsion, the model accounted for x-ray conversion to electron-hole (e-h) pairs, integration of e-h pairs in detector elements, electronic noise, and energy thresholding. The probability density function (PDF) describing the number of e-h pairs was propagated through each stage of the model and was used to derive new theoretical expressions for the large-area gain and modulation transfer function (MTF) of CdTe SPC x-ray detectors, and the energy bin sensitivity functions and MTFs of CdTe spectroscopic detectors. Theoretical predictions were compared with the results of MATLAB-based Monte Carlo (MC) simulations and published data. Comparisons were also made with the MTF of energy-integrating systems. Under general radiographic conditions, reabsorption, diffusion, and Coulomb repulsion together artificially inflate count rates by 20% to 50%. For thicker converters (e.g. 1000 μm) and larger detector elements (e.g. 500 μm pixel pitch) these processes result in modest inflation (i.e. ∼10%) in apparent count rates. Our theoretical and MC analyses predict that SPC MTFs will be degraded relative to those of energy-integrating systems for fluoroscopic, general radiographic, and CT imaging conditions. In most cases, this degradation is modest (i.e., ∼10% at the Nyquist frequency). However, for thicker converters, the SPC MTF can be degraded

  6. Fluorescence detection of single molecules using pulsed near-field optical excitation and time correlated photon counting

    International Nuclear Information System (INIS)

    Ambrose, W.P.; Goodwin, P.M.; Martin, J.C.; Keller, R.A.

    1994-01-01

    Pulsed excitation, time correlated single photon counting and time gated detection are used in near-field optical microscopy to enhance fluorescence images and measure the fluorescence lifetimes of single molecules of Rhodamine 6G on silica surfaces. Time gated detection is used to reject prompt scattered background and to improve the image signal to noise ratio. The excited state lifetime of a single Rhodamine 6G molecule is found to depend on the position of the near-field probe. We attribute the lifetime variations to spontaneous emission rate alterations by the fluorescence reflected from and quenching by the aluminum coated probe

  7. Feasibility of using single photon counting X-ray for lung tumor position estimation based on 4D-CT

    Energy Technology Data Exchange (ETDEWEB)

    Aschenbrenner, Katharina P.; Hesser, Juergen W. [Heidelberg Univ., Mannheim (Germany). Dept. of Experimental Radiation Oncology; Heidelberg Univ. (Germany). IWR; Guthier, Christian V. [Heidelberg Univ., Mannheim (Germany). Dept. of Experimental Radiation Oncology; Lyatskaya, Yulia [Brigham and Women' s Center, Boston, MA (United States); Harvard Medical School, Boston, MA (United States); Boda-Heggemann, Judit; Wenz, Frederik [Heidelberg Univ., Mannheim (Germany). Dept. of Radiation Oncology

    2017-10-01

    In stereotactic body radiation therapy of lung tumors, reliable position estimation of the tumor is necessary in order to minimize normal tissue complication rate. While kV X-ray imaging is frequently used, continuous application during radiotherapy sessions is often not possible due to concerns about the additional dose. Thus, ultra low-dose (ULD) kV X-ray imaging based on a single photon counting detector is suggested. This paper addresses the lower limit of photons to locate the tumor reliably with an accuracy in the range of state-of-the-art methods, i.e. a few millimeters. 18 patient cases with four dimensional CT (4D-CT), which serves as a-priori information, are included in the study. ULD cone beam projections are simulated from the 4D-CTs including Poisson noise. The projections from the breathing phases which correspond to different tumor positions are compared to the ULD projection by means of Poisson log-likelihood (PML) and correlation coefficient (CC), and template matching under these metrics. The results indicate that in full thorax imaging five photons per pixel suffice for a standard deviation in tumor positions of less than half a breathing phase. Around 50 photons per pixel are needed to achieve this accuracy with the field of view restricted to the tumor region. Compared to CC, PML tends to perform better for low photon counts and shifts in patient setup. Template matching only improves the position estimation in high photon counts. The quality of the reconstruction is independent of the projection angle. The accuracy of the proposed ULD single photon counting system is in the range of a few millimeters and therefore comparable to state-of-the-art tumor tracking methods. At the same time, a reduction in photons per pixel by three to four orders of magnitude relative to commercial systems with flatpanel detectors can be achieved. This enables continuous kV image-based position estimation during all fractions since the additional dose to the

  8. Feasibility of using single photon counting X-ray for lung tumor position estimation based on 4D-CT.

    Science.gov (United States)

    Aschenbrenner, Katharina P; Guthier, Christian V; Lyatskaya, Yulia; Boda-Heggemann, Judit; Wenz, Frederik; Hesser, Jürgen W

    2017-09-01

    In stereotactic body radiation therapy of lung tumors, reliable position estimation of the tumor is necessary in order to minimize normal tissue complication rate. While kV X-ray imaging is frequently used, continuous application during radiotherapy sessions is often not possible due to concerns about the additional dose. Thus, ultra low-dose (ULD) kV X-ray imaging based on a single photon counting detector is suggested. This paper addresses the lower limit of photons to locate the tumor reliably with an accuracy in the range of state-of-the-art methods, i.e. a few millimeters. 18 patient cases with four dimensional CT (4D-CT), which serves as a-priori information, are included in the study. ULD cone beam projections are simulated from the 4D-CTs including Poisson noise. The projections from the breathing phases which correspond to different tumor positions are compared to the ULD projection by means of Poisson log-likelihood (PML) and correlation coefficient (CC), and template matching under these metrics. The results indicate that in full thorax imaging five photons per pixel suffice for a standard deviation in tumor positions of less than half a breathing phase. Around 50 photons per pixel are needed to achieve this accuracy with the field of view restricted to the tumor region. Compared to CC, PML tends to perform better for low photon counts and shifts in patient setup. Template matching only improves the position estimation in high photon counts. The quality of the reconstruction is independent of the projection angle. The accuracy of the proposed ULD single photon counting system is in the range of a few millimeters and therefore comparable to state-of-the-art tumor tracking methods. At the same time, a reduction in photons per pixel by three to four orders of magnitude relative to commercial systems with flatpanel detectors can be achieved. This enables continuous kV image-based position estimation during all fractions since the additional dose to the

  9. Discrimination Voltage and Overdrive Bias Dependent Performance Evaluation of Passively Quenched SiC Single-Photon-Counting Avalanche Photodiodes

    International Nuclear Information System (INIS)

    Liu Fei; Yang Sen; Zhou Dong; Lu Hai; Zhang Rong; Zheng You-Dou

    2015-01-01

    In many critical civil and emerging military applications, low-level UV detection, sometimes at single photon level, is highly desired. In this work, a mesa-type 4H-SiC UV avalanche photodiode (APD) is designed and fabricated, which exhibits low leakage current and high avalanche gain. When studied by using a passive quenching circuit, the APD exhibits self-quenching characteristics due to its high differential resistance in the avalanche region. The single photon detection efficiency and dark count rate of the APD are evaluated as functions of discrimination voltage and over-drive voltage. The optimized operation conditions of the single photon counting APD are discussed. (paper)

  10. Feasibility of using single photon counting X-ray for lung tumor position estimation based on 4D-CT

    International Nuclear Information System (INIS)

    Aschenbrenner, Katharina P.; Hesser, Juergen W.; Boda-Heggemann, Judit; Wenz, Frederik

    2017-01-01

    In stereotactic body radiation therapy of lung tumors, reliable position estimation of the tumor is necessary in order to minimize normal tissue complication rate. While kV X-ray imaging is frequently used, continuous application during radiotherapy sessions is often not possible due to concerns about the additional dose. Thus, ultra low-dose (ULD) kV X-ray imaging based on a single photon counting detector is suggested. This paper addresses the lower limit of photons to locate the tumor reliably with an accuracy in the range of state-of-the-art methods, i.e. a few millimeters. 18 patient cases with four dimensional CT (4D-CT), which serves as a-priori information, are included in the study. ULD cone beam projections are simulated from the 4D-CTs including Poisson noise. The projections from the breathing phases which correspond to different tumor positions are compared to the ULD projection by means of Poisson log-likelihood (PML) and correlation coefficient (CC), and template matching under these metrics. The results indicate that in full thorax imaging five photons per pixel suffice for a standard deviation in tumor positions of less than half a breathing phase. Around 50 photons per pixel are needed to achieve this accuracy with the field of view restricted to the tumor region. Compared to CC, PML tends to perform better for low photon counts and shifts in patient setup. Template matching only improves the position estimation in high photon counts. The quality of the reconstruction is independent of the projection angle. The accuracy of the proposed ULD single photon counting system is in the range of a few millimeters and therefore comparable to state-of-the-art tumor tracking methods. At the same time, a reduction in photons per pixel by three to four orders of magnitude relative to commercial systems with flatpanel detectors can be achieved. This enables continuous kV image-based position estimation during all fractions since the additional dose to the

  11. Secondary scintillation yield from GEM and THGEM gaseous electron multipliers for direct dark matter search

    Science.gov (United States)

    Monteiro, C. M. B.; Fernandes, L. M. P.; Veloso, J. F. C. A.; Oliveira, C. A. B.; dos Santos, J. M. F.

    2012-07-01

    The search for alternatives to PMTs as photosensors in optical TPCs for rare event detection has significantly increased in the last few years. In particular, in view of the next generation large volume detectors, the use of photosensors with lower natural radioactivity, such as large area APDs or GM-APDs, with the additional possibility of sparse surface coverage, triggered the intense study of secondary scintillation production in micropattern electron multipliers, such as GEMs and THGEMs, as alternatives to the commonly used uniform electric field region between two parallel meshes. The much higher scintillation output obtained from the electron avalanches in such microstructures presents an advantage in those situations. The accurate knowledge of the amount of such scintillation is important for correct detector simulation and optimization. It will also serve as a benchmark for software tools developed and/or under development for the calculation of the amount of such scintillation.The secondary scintillation yield, or electroluminescence yield, in the electron avalanches of GEMs and THGEMs operating in gaseous xenon and argon has been determined for different gas pressures. At 1 bar, THGEMs deliver electroluminescence yields that are more than one order of magnitude higher when compared to those achieved in GEMs and two orders of magnitude when compared to those achieved in a uniform field gap. The THGEM electroluminescence yield presents a faster decrease with pressure when comparing to the GEM electroluminescence yield, reaching similar values to what is achieved in GEMs for xenon pressures of 2.5 bar, but still one order of magnitude higher than that produced in a uniform field gap. Another exception is the GEM operating in argon, which presents an electroluminescence yield similar to that produced in a uniform electric field gap, while the THGEM achieves yields that are more than one order of magnitude higher.

  12. Low-Noise Free-Running High-Rate Photon-Counting for Space Communication and Ranging

    Science.gov (United States)

    Lu, Wei; Krainak, Michael A.; Yang, Guan; Sun, Xiaoli; Merritt, Scott

    2016-01-01

    We present performance data for low-noise free-running high-rate photon counting method for space optical communication and ranging. NASA GSFC is testing the performance of two types of novel photon-counting detectors 1) a 2x8 mercury cadmium telluride (HgCdTe) avalanche array made by DRS Inc., and a 2) a commercial 2880-element silicon avalanche photodiode (APD) array. We successfully measured real-time communication performance using both the 2 detected-photon threshold and logic AND-gate coincidence methods. Use of these methods allows mitigation of dark count, after-pulsing and background noise effects without using other method of Time Gating The HgCdTe APD array routinely demonstrated very high photon detection efficiencies (50) at near infrared wavelength. The commercial silicon APD array exhibited a fast output with rise times of 300 ps and pulse widths of 600 ps. On-chip individually filtered signals from the entire array were multiplexed onto a single fast output. NASA GSFC has tested both detectors for their potential application for space communications and ranging. We developed and compare their performances using both the 2 detected photon threshold and coincidence methods.

  13. Technical feasibility proof for high-resolution low-dose photon-counting CT of the breast

    Energy Technology Data Exchange (ETDEWEB)

    Kalender, Willi A.; Kolditz, Daniel; Lueck, Ferdinand [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); CT Imaging GmbH, Erlangen (Germany); Steiding, Christian [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); CT Imaging GmbH, Erlangen (Germany); University Hospital of Erlangen, Institute of Radiology, Erlangen (Germany); Ruth, Veikko; Roessler, Ann-Christin [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); Wenkel, Evelyn [University Hospital of Erlangen, Institute of Radiology, Erlangen (Germany)

    2017-03-15

    X-ray computed tomography (CT) has been proposed and evaluated multiple times as a potentially alternative method for breast imaging. All efforts shown so far have been criticized and partly disapproved because of their limited spatial resolution and higher patient dose when compared to mammography. Our concept for a dedicated breast CT (BCT) scanner therefore aimed at novel apparatus and detector design to provide high spatial resolution of about 100 μm and average glandular dose (AGD) levels of 5 mGy or below. Photon-counting technology was considered as a solution to reach these goals. The complete concept was previously evaluated and confirmed by simulations and basic experiments on laboratory setups. We here present measurements of dose, technical image quality parameters and surgical specimen results on such a scanner. For comparison purposes, the specimens were also imaged with digital mammography (DM) and breast tomosynthesis (BT) apparatus. Results show that photon-counting BCT (pcBCT) at 5 mGy AGD offers sufficiently high 3D spatial resolution for reliable detectability of calcifications and soft tissue delineation. (orig.)

  14. Development of a Schottky CdTe Medipix3RX hybrid photon counting detector with spatial and energy resolving capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Gimenez, E.N., E-mail: Eva.Gimenez@diamond.ac.uk [Diamond Light Source, Harwell Campus, Oxforshire OX11 0DE (United Kingdom); Astromskas, V. [University of Surrey (United Kingdom); Horswell, I.; Omar, D.; Spiers, J.; Tartoni, N. [Diamond Light Source, Harwell Campus, Oxforshire OX11 0DE (United Kingdom)

    2016-07-11

    A multichip CdTe-Medipix3RX detector system was developed in order to bring the advantages of photon-counting detectors to applications in the hard X-ray range of energies. The detector head consisted of 2×2 Medipix3RX ASICs bump-bonded to a 28 mm×28 mm e{sup −} collection Schottky contact CdTe sensor. Schottky CdTe sensors undergo performance degrading polarization which increases with temperature, flux and the longer the HV is applied. Keeping the temperature stable and periodically refreshing the high voltage bias supply was used to minimize the polarization and achieve a stable and reproducible detector response. This leads to good quality images and successful results on the energy resolving capabilities of the system. - Highlights: • A high atomic number (CdTe sensor based) photon-counting detector was developed. • Polarization effects affected the image were minimized by regularly refreshing the bias voltage and stabilizing the temperature. • Good spatial resolution and image quality was achieved following this procedure.

  15. X-ray imaging with sub-micron resolution using large-area photon counting detectors Timepix

    Science.gov (United States)

    Dudak, J.; Karch, J.; Holcova, K.; Zemlicka, J.

    2017-12-01

    As X-ray micro-CT became a popular tool for scientific purposes a number of commercially available CT systems have emerged on the market. Micro-CT systems have, therefore, become widely accessible and the number of research laboratories using them constantly increases. However, even when CT scans with spatial resolution of several micrometers can be performed routinely, data acquisition with sub-micron precision remains a complicated task. Issues come mostly from prolongation of the scan time inevitably connected with the use of nano-focus X-ray sources. Long exposure time increases the noise level in the CT projections. Furthermore, considering the sub-micron resolution even effects like source-spot drift, rotation stage wobble or thermal expansion become significant and can negatively affect the data. The use of dark-current free photon counting detectors as X-ray cameras for such applications can limit the issue of increased image noise in the data, however the mechanical stability of the whole system still remains a problem and has to be considered. In this work we evaluate the performance of a micro-CT system equipped with nano-focus X-ray tube and a large area photon counting detector Timepix for scans with effective pixel size bellow one micrometer.

  16. Microcomputed tomography with a second generation photon-counting x-ray detector: contrast analysis and material separation

    Science.gov (United States)

    Wang, X.; Meier, D.; Oya, P.; Maehlum, G. E.; Wagenaar, D. J.; Tsui, B. M. W.; Patt, B. E.; Frey, E. C.

    2010-04-01

    The overall aim of this work was to evaluate the potential for improving in vivo small animal microCT through the use of an energy resolved photon-counting detector. To this end, we developed and evaluated a prototype microCT system based on a second-generation photon-counting x-ray detector which simultaneously counted photons with energies above six energy thresholds. First, we developed a threshold tuning procedure to reduce the dependence of detector uniformity and to reduce ring artifacts. Next, we evaluated the system in terms of the contrast-to-noise ratio in different energy windows for different target materials. These differences provided the possibility to weight the data acquired in different windows in order to optimize the contrast-to-noise ratio. We also explored the ability of the system to use data from different energy windows to aid in distinguishing various materials. We found that the energy discrimination capability provided the possibility for improved contrast-to-noise ratios and allowed separation of more than two materials, e.g., bone, soft-tissue and one or more contrast materials having K-absorption edges in the energy ranges of interest.

  17. A comparative analysis of OTF, NPS, and DQE in energy integrating and photon counting digital x-ray detectors

    International Nuclear Information System (INIS)

    Acciavatti, Raymond J.; Maidment, Andrew D. A.

    2010-01-01

    Purpose: One of the benefits of photon counting (PC) detectors over energy integrating (EI) detectors is the absence of many additive noise sources, such as electronic noise and secondary quantum noise. The purpose of this work is to demonstrate that thresholding voltage gains to detect individual x rays actually generates an unexpected source of white noise in photon counters. Methods: To distinguish the two detector types, their point spread function (PSF) is interpreted differently. The PSF of the energy integrating detector is treated as a weighting function for counting x rays, while the PSF of the photon counting detector is interpreted as a probability. Although this model ignores some subtleties of real imaging systems, such as scatter and the energy-dependent amplification of secondary quanta in indirect-converting detectors, it is useful for demonstrating fundamental differences between the two detector types. From first principles, the optical transfer function (OTF) is calculated as the continuous Fourier transform of the PSF, the noise power spectra (NPS) is determined by the discrete space Fourier transform (DSFT) of the autocovariance of signal intensity, and the detective quantum efficiency (DQE) is found from combined knowledge of the OTF and NPS. To illustrate the calculation of the transfer functions, the PSF is modeled as the convolution of a Gaussian with the product of rect functions. The Gaussian reflects the blurring of the x-ray converter, while the rect functions model the sampling of the detector. Results: The transfer functions are first calculated assuming outside noise sources such as electronic noise and secondary quantum noise are negligible. It is demonstrated that while OTF is the same for two detector types possessing an equivalent PSF, a frequency-independent (i.e., ''white'') difference in their NPS exists such that NPS PC ≥NPS EI and hence DQE PC ≤DQE EI . The necessary and sufficient condition for equality is that the PSF

  18. ChromAIX2: A large area, high count-rate energy-resolving photon counting ASIC for a Spectral CT Prototype

    Science.gov (United States)

    Steadman, Roger; Herrmann, Christoph; Livne, Amir

    2017-08-01

    Spectral CT based on energy-resolving photon counting detectors is expected to deliver additional diagnostic value at a lower dose than current state-of-the-art CT [1]. The capability of simultaneously providing a number of spectrally distinct measurements not only allows distinguishing between photo-electric and Compton interactions but also discriminating contrast agents that exhibit a K-edge discontinuity in the absorption spectrum, referred to as K-edge Imaging [2]. Such detectors are based on direct converting sensors (e.g. CdTe or CdZnTe) and high-rate photon counting electronics. To support the development of Spectral CT and show the feasibility of obtaining rates exceeding 10 Mcps/pixel (Poissonian observed count-rate), the ChromAIX ASIC has been previously reported showing 13.5 Mcps/pixel (150 Mcps/mm2 incident) [3]. The ChromAIX has been improved to offer the possibility of a large area coverage detector, and increased overall performance. The new ASIC is called ChromAIX2, and delivers count-rates exceeding 15 Mcps/pixel with an rms-noise performance of approximately 260 e-. It has an isotropic pixel pitch of 500 μm in an array of 22×32 pixels and is tile-able on three of its sides. The pixel topology consists of a two stage amplifier (CSA and Shaper) and a number of test features allowing to thoroughly characterize the ASIC without a sensor. A total of 5 independent thresholds are also available within each pixel, allowing to acquire 5 spectrally distinct measurements simultaneously. The ASIC also incorporates a baseline restorer to eliminate excess currents induced by the sensor (e.g. dark current and low frequency drifts) which would otherwise cause an energy estimation error. In this paper we report on the inherent electrical performance of the ChromAXI2 as well as measurements obtained with CZT (CdZnTe)/CdTe sensors and X-rays and radioactive sources.

  19. High Flux Energy-Resolved Photon-Counting X-Ray Imaging Arrays with CdTe and CdZnTe for Clinical CT

    International Nuclear Information System (INIS)

    Barber, William C.; Hartsough, Neal E.; Gandhi, Thulasidharan; Iwanczyk, Jan S.; Wessel, Jan C.; Nygard, Einar; Malakhov, Nail; Wawrzyniak, Gregor; Dorholt, Ole; Danielsen, Roar

    2013-06-01

    We have fabricated fast room-temperature energy dispersive photon counting x-ray imaging arrays using pixellated cadmium zinc (CdTe) and cadmium zinc telluride (CdZnTe) semiconductors. We have also fabricated fast application specific integrated circuits (ASICs) with a two dimensional (2D) array of inputs for readout from the CdZnTe sensors. The new CdTe and CdZnTe sensors have a 2D array of pixels with a 0.5 mm pitch and can be tiled in 2D. The new 2D ASICs have four energy discriminators per pixel with a linear energy response across the entire dynamic range for clinical CT. The ASICs can also be tiled in 2D and are designed to fit within the active area of the 2D sensors. We have measured several important performance parameters including; an output count rate (OCR) in excess of 20 million counts per second per square mm, an energy resolution of 7 keV full width at half maximum (FWHM) across the entire dynamic range, and a noise floor less than 20 keV. This is achieved by directly interconnecting the ASIC inputs to the pixels of the CdTE and CdZnTe sensors incurring very little additional capacitance. We present a comparison of the performance of the CdTe and CdZnTe sensors including the OCR, FWHM energy resolution, and noise floor. (authors)

  20. Scintillator structure

    International Nuclear Information System (INIS)

    Cusano, D.A.; Prener, J.S.

    1979-01-01

    A scintillator structure comprises at least one layer of transparent fused quartz with a phosphor coating on one or both sides adjacent to at least one transparent layer of epoxy resin which directs light from the phosphor to a detector. The phosphor layer may be formed from a powder optionally with a binder, a single crystal or a melt, or by evaporation or sintering. A plurality of multiple layers may be used or the structure tilted for greater absorption. The structure may be surrounded by another such structure optionally operating in cascade with the first. Many phosphors are specified. A scintillator structure comprises phosphor particles dispersed in epoxy resin or copoly imide-silicone and cast in a multi-compartment box with long sides transparent to X-rays and dividers opaque to X-rays. (UK)

  1. Absolute dose calibration of an X-ray system and dead time investigations of photon-counting techniques

    CERN Document Server

    Carpentieri, C; Ludwig, J; Ashfaq, A; Fiederle, M

    2002-01-01

    High precision concerning the dose calibration of X-ray sources is required when counting and integrating methods are compared. The dose calibration for a dental X-ray tube was executed with special dose calibration equipment (dosimeter) as function of exposure time and rate. Results were compared with a benchmark spectrum and agree within +-1.5%. Dead time investigations with the Medipix1 photon-counting chip (PCC) have been performed by rate variations. Two different types of dead time, paralysable and non-paralysable will be discussed. The dead time depends on settings of the front-end electronics and is a function of signal height, which might lead to systematic defects of systems. Dead time losses in excess of 30% have been found for the PCC at 200 kHz absorbed photons per pixel.

  2. Development of windows based software to analyze fluorescence decay with time-correlated single photon counting (TCSPC) setup

    International Nuclear Information System (INIS)

    Mallick, M.B.; Ravindranath, S.V.G.; Das, N.C.

    2002-07-01

    A VUV spectroscopic facility for studies in photophysics and photochemistry is being set up at INDUS-I synchrotron source, CAT, Indore. For this purpose, a data acquisition system based on time-correlated single photon counting method is being developed for fluorescence lifetime measurement. To estimate fluorescence lifetime from the data collected with this sytem, a Windows based program has been developed using Visual Basic 5.0. It uses instrument response function (IRF) and observed decay curve and estimates parameters of single exponential decay by least square analysis and Marquardt method as convergence mechanism. Estimation of parameters was performed using data collected with a commercial setup. Goodness of fit was judged by evaluating χR 2 , weighted residuals and autocorrelation function. Performance is compared with two commercial software packages and found to be satisfactory. (author)

  3. Picosecond wide-field time-correlated single photon counting fluorescence microscopy with a delay line anode detector

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, Liisa M.; Le Marois, Alix; Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Becker, Wolfgang; Smietana, Stefan [Becker & Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin (Germany); Milnes, James; Conneely, Thomas [Photek Ltd., 26 Castleham Rd, Saint Leonards-on-Sea TN38 9NS (United Kingdom); Jagutzki, Ottmar [Institut für Kernphysik, Max-von-Laue-Str. 1, 60438 Frankfurt (Germany)

    2016-08-15

    We perform wide-field time-correlated single photon counting-based fluorescence lifetime imaging (FLIM) with a crossed delay line anode image intensifier, where the pulse propagation time yields the photon position. This microchannel plate-based detector was read out with conventional fast timing electronics and mounted on a fluorescence microscope with total internal reflection (TIR) illumination. The picosecond time resolution of this detection system combines low illumination intensity of microwatts with wide-field data collection. This is ideal for fluorescence lifetime imaging of cell membranes using TIR. We show that fluorescence lifetime images of living HeLa cells stained with membrane dye di-4-ANEPPDHQ exhibit a reduced lifetime near the coverslip in TIR compared to epifluorescence FLIM.

  4. Wide-field time-correlated single photon counting (TCSPC) microscopy with time resolution below the frame exposure time

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, Liisa M. [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Petrášek, Zdeněk [Max Planck Institute of Biochemistry, Department of Cellular and Molecular Biophysics, Am Klopferspitz 18, D-82152 Martinsried (Germany); Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom)

    2015-07-01

    Fast frame rate CMOS cameras in combination with photon counting intensifiers can be used for fluorescence imaging with single photon sensitivity at kHz frame rates. We show here how the phosphor decay of the image intensifier can be exploited for accurate timing of photon arrival well below the camera exposure time. This is achieved by taking ratios of the intensity of the photon events in two subsequent frames, and effectively allows wide-field TCSPC. This technique was used for measuring decays of ruthenium compound Ru(dpp) with lifetimes as low as 1 μs with 18.5 μs frame exposure time, including in living HeLa cells, using around 0.1 μW excitation power. We speculate that by using an image intensifier with a faster phosphor decay to match a higher camera frame rate, photon arrival time measurements on the nanosecond time scale could well be possible.

  5. Chip-interleaved optical code division multiple access relying on a photon-counting iterative successive interference canceller for free-space optical channels.

    Science.gov (United States)

    Zhou, Xiaolin; Zheng, Xiaowei; Zhang, Rong; Hanzo, Lajos

    2013-07-01

    In this paper, we design a novel Poisson photon-counting based iterative successive interference cancellation (SIC) scheme for transmission over free-space optical (FSO) channels in the presence of both multiple access interference (MAI) as well as Gamma-Gamma atmospheric turbulence fading, shot-noise and background light. Our simulation results demonstrate that the proposed scheme exhibits a strong MAI suppression capability. Importantly, an order of magnitude of BER improvements may be achieved compared to the conventional chip-level optical code-division multiple-access (OCDMA) photon-counting detector.

  6. A High-Speed, Event-Driven, Active Pixel Sensor Readout for Photon-Counting Microchannel Plate Detectors

    Science.gov (United States)

    Kimble, Randy A.; Pain, Bedabrata; Norton, Timothy J.; Haas, J. Patrick; Oegerle, William R. (Technical Monitor)

    2002-01-01

    Silicon array readouts for microchannel plate intensifiers offer several attractive features. In this class of detector, the electron cloud output of the MCP intensifier is converted to visible light by a phosphor; that light is then fiber-optically coupled to the silicon array. In photon-counting mode, the resulting light splashes on the silicon array are recognized and centroided to fractional pixel accuracy by off-chip electronics. This process can result in very high (MCP-limited) spatial resolution while operating at a modest MCP gain (desirable for dynamic range and long term stability). The principal limitation of intensified CCD systems of this type is their severely limited local dynamic range, as accurate photon counting is achieved only if there are not overlapping event splashes within the frame time of the device. This problem can be ameliorated somewhat by processing events only in pre-selected windows of interest of by using an addressable charge injection device (CID) for the readout array. We are currently pursuing the development of an intriguing alternative readout concept based on using an event-driven CMOS Active Pixel Sensor. APS technology permits the incorporation of discriminator circuitry within each pixel. When coupled with suitable CMOS logic outside the array area, the discriminator circuitry can be used to trigger the readout of small sub-array windows only when and where an event splash has been detected, completely eliminating the local dynamic range problem, while achieving a high global count rate capability and maintaining high spatial resolution. We elaborate on this concept and present our progress toward implementing an event-driven APS readout.

  7. Detection of the scintillation light emitted from direct-bandgap compound semiconductors by a Si avalanche photodiode at 150 mK

    International Nuclear Information System (INIS)

    Yasumune, Takashi; Takayama, Nobuyasu; Maehata, Keisuke; Ishibashi, Kenji; Umeno, Takahiro

    2008-01-01

    In this work, the direct-bandgap compound semiconductor materials are irradiated by α particles emitted from 241 Am for the detection of scintillation light at the temperature of 150 mK. For the irradiation experiment, two disk shaped samples were fabricated from an epoxy resin mixed with the powder of PbI 2 and CuI, respectively. Each disk-samples was cooled down to 150 mK by a compact liquid helium-free dilution refrigerator. A Si avalanche photodiode (APD) was employed for detecting the scintillation light emitted from the disk-sample inside the refrigerator. The detection signal current of Si APD was converted into the voltage pulses by a charge sensitive preamplifier. The voltage pulses of the scintillation light emitted from the direct-bandgap semiconductors were observed at the temperature of 150 mK. (author)

  8. Functioning of the Cartogam portable gamma camera in a photon counting mode (this development is performed at CEA in the framework of the B01-05 common interest program between CEA and COGEMA

    International Nuclear Information System (INIS)

    Gal, O.; Dessus, B.; Laine, F.; Jean, F.; Leveque, C.

    2001-01-01

    The CARTOGAM portable gamma camera, which is particularly compact (15 Kg in mass, including the shield, 8 cm in diameter), has been developed for gamma imaging applications in nuclear facilities. The detector is composed of a CsI(Tl) scintillator, an image intensifier and a CCD matrix. The ordinary mode for image acquisition with such a detector is an integrating mode: signal accumulated in the CCD pixels is read at the end of the exposure time, or even periodically with a summation in a PC memory. The main sources of noise in that mode are the photo-cathode thermo-electronic emission and the CCD leaking pixels. We have developed an alternative acquisition mode based on a morphological processing of the elementary images at the video frequency (25 images/s). In that mode, gamma events are individually identified and the noise due to isolated thermo-electrons or white pixels is (almost) completely removed, thus leading to an important gain in camera sensitivity. We present here experimental results obtained in this photon counting mode concerning SNR, spatial resolution, saturation limit in dose rate, sensitivity and comparison with the integrating mode. We present also a short analysis of the problem of measuring the SNR in practice in such images. (author)

  9. Feasibility of photon-counting K-edge imaging in X-ray and computed tomographic systems: Monte Carlo simulation studies

    International Nuclear Information System (INIS)

    Lee, Seung-Wan; Choi, Yu-Na; Cho, Hyo-Min; Lee, Young-Jin; Ryu, Hyun-Ju; Kim, Hee-Joung

    2011-01-01

    Conventional X-ray systems and X-ray computed tomography (CT) systems, which use detectors operated in the integrating mode, are not able to reflect spectral information because the detector output is proportional to the energy fluence integrated over the whole spectrum. Photon-counting detectors have been considered as alternative devices. These detectors can measure the photon energy deposited by each event and improve the image quality. In this study, we investigated the feasibility of K-edge imaging using a photon-counting detector and evaluated the capability of material decomposition in X-ray images. The geometries of X-ray imaging systems equipped with cadmium telluride (CdTe) detectors and phantoms consisting of different materials were designed using Geant4 Application for Tomographic Emission (GATE) version 6.0. To observe the effect of a discontinuity in the attenuation due to the K-edge of a high atomic number material, we chose the energy windows to be one below and one above the K-edge absorption energy of the target material. The contrast-to-noise ratios (CNRs) of the target materials were increased at selective energy levels above the K-edge absorption energy because the attenuation is more dramatically increased at energies above the K-edge absorption energy of the material than at energies below that. The CNRs for the target materials in the K-edge image were proportional to the material concentration. The results of this study show that K-edge imaging can be carried out in conventional X-ray systems and X-ray CT systems using CdTe photon-counting detectors and that the target materials can be separated from background materials by using K-edge imaging. The photon-counting detector has potential to provide improved image quality, and this study will be used as a basis for future studies on photon-counting X-ray imaging.

  10. TU-FG-209-03: Exploring the Maximum Count Rate Capabilities of Photon Counting Arrays Based On Polycrystalline Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Liang, A K; Koniczek, M; Antonuk, L E; El-Mohri, Y; Zhao, Q [University of Michigan, Ann Arbor, MI (United States)

    2016-06-15

    Purpose: Photon counting arrays (PCAs) offer several advantages over conventional, fluence-integrating x-ray imagers, such as improved contrast by means of energy windowing. For that reason, we are exploring the feasibility and performance of PCA pixel circuitry based on polycrystalline silicon. This material, unlike the crystalline silicon commonly used in photon counting detectors, lends itself toward the economic manufacture of radiation tolerant, monolithic large area (e.g., ∼43×43 cm2) devices. In this presentation, exploration of maximum count rate, a critical performance parameter for such devices, is reported. Methods: Count rate performance for a variety of pixel circuit designs was explored through detailed circuit simulations over a wide range of parameters (including pixel pitch and operating conditions) with the additional goal of preserving good energy resolution. The count rate simulations assume input events corresponding to a 72 kVp x-ray spectrum with 20 mm Al filtration interacting with a CZT detector at various input flux rates. Output count rates are determined at various photon energy threshold levels, and the percentage of counts lost (e.g., due to deadtime or pile-up) is calculated from the ratio of output to input counts. The energy resolution simulations involve thermal and flicker noise originating from each circuit element in a design. Results: Circuit designs compatible with pixel pitches ranging from 250 to 1000 µm that allow count rates over a megacount per second per pixel appear feasible. Such rates are expected to be suitable for radiographic and fluoroscopic imaging. Results for the analog front-end circuitry of the pixels show that acceptable energy resolution can also be achieved. Conclusion: PCAs created using polycrystalline silicon have the potential to offer monolithic large-area detectors with count rate performance comparable to those of crystalline silicon detectors. Further improvement through detailed circuit

  11. Scintillation scanner

    International Nuclear Information System (INIS)

    Mehrbrodt, A.W.; Mog, W.F.; Brunnett, C.J.

    1977-01-01

    A scintillation scanner having a visual image producing means coupled through a lost motion connection to the boom which supports the scintillation detector is described. The lost motion connection is adjustable to compensate for such delays as may occur between sensing and recording scintillations. 13 claims, 5 figures

  12. Detectors for proton counting. Si-APD and scintillation detectors

    International Nuclear Information System (INIS)

    Kishimoto, Shunji

    2008-01-01

    Increased intensity of synchrotron radiation requests users to prepare photon pulse detectors having higher counting rates. As detectors for photon counting, silicon-avalanche photodiode (Si-APD) and scintillation detectors were chosen for the fifth series of detectors. Principle of photon detection by pulse and need of amplification function of the detector were described. Structure and working principle, high counting rate measurement system, bunch of electrons vs. counting rate, application example of NMR time spectroscopy measurement and comments for users were described for the Si-APD detector. Structure of scintillator and photomultiplier tube, characteristics of scintillator and performance of detector were shown for the NaI detector. Future development of photon pulse detectors was discussed. (T. Tanaka)

  13. AURORA on MEGSAT 1 a photon counting observatory for the Earth UV night-sky background and Aurora emission

    CERN Document Server

    Monfardini, A; Stalio, R; Mahne, N; Battiston, R; Menichelli, M; Mazzinghi, P

    2001-01-01

    A low-mass, low-cost photon-counting scientific payload has been developed and launched on a commercial microsatellite in order to study the near-UV night-sky background emission with a telescope nicknamed 'Notte' and the Aurora emission with 'Alba'. AURORA, this is the name of the experiment, will determine, with the 'Notte' channel, the overall night-side photon background in the 300-400 nm spectral range, together with a particular 2 sup + N sub 2 line (lambda sub c =337 nm). The 'Alba' channel, on the other hand, will study the Aurora emissions in four different spectral bands (FWHM=8.4-9.6 nm) centered on: 367 nm (continuum evaluation), 391 nm (1 sup - N sup + sub 2), 535 nm (continuum evaluation), 560 nm (OI). The instrument has been launched on the 26 September, 2000 from the Baikonur cosmodrome on a modified SS18 Dnepr-1 'Satan' rocket. The satellite orbit is nearly circular (h sub a sub p sub o sub g sub e sub e =648 km, e=0.0022), and the inclination of the orbital plane is 64.56 deg. An overview of...

  14. AURORA on MEGSAT 1: a photon counting observatory for the Earth UV night-sky background and Aurora emission

    International Nuclear Information System (INIS)

    Monfardini, A.; Trampus, P.; Stalio, R.; Mahne, N.; Battiston, R.; Menichelli, M.; Mazzinghi, P.

    2001-01-01

    A low-mass, low-cost photon-counting scientific payload has been developed and launched on a commercial microsatellite in order to study the near-UV night-sky background emission with a telescope nicknamed 'Notte' and the Aurora emission with 'Alba'. AURORA, this is the name of the experiment, will determine, with the 'Notte' channel, the overall night-side photon background in the 300-400 nm spectral range, together with a particular 2 + N 2 line (λ c =337 nm). The 'Alba' channel, on the other hand, will study the Aurora emissions in four different spectral bands (FWHM=8.4-9.6 nm) centered on: 367 nm (continuum evaluation), 391 nm (1 - N + 2 ), 535 nm (continuum evaluation), 560 nm (OI). The instrument has been launched on the 26 September, 2000 from the Baikonur cosmodrome on a modified SS18 Dnepr-1 'Satan' rocket. The satellite orbit is nearly circular (h apogee =648 km, e=0.0022), and the inclination of the orbital plane is 64.56 deg. An overview of the techniques adopted is given in this paper

  15. Performance of a single photon counting microstrip detector for strip pitches down to 10 μm

    International Nuclear Information System (INIS)

    Bergamaschi, A.; Broennimann, Ch.; Dinapoli, R.; Eikenberry, E.; Gozzo, F.; Henrich, B.; Kobas, M.; Kraft, P.; Patterson, B.; Schmitt, B.

    2008-01-01

    The MYTHEN detector is a one-dimensional microstrip detector with single photon counting readout optimized for time resolved powder diffraction experiments at the Swiss Light Source (SLS). The system has been successfully tested for many different synchrotron radiation applications including phase contrast and tomographic imaging, small angle scattering, diffraction and time resolved pump and probe experiments for X-ray energies down to 5 keV and counting rate up to 3 MHz. The frontend electronics is designed in order to be coupled to 50 μm pitch microstrip sensors but some interest in enhancing the spatial resolution is arising for imaging and powder diffraction experiments. A test structure with strip pitches in the range 10-50 μm has been tested and the gain and noise on the readout electronics have been measured for the different strip pitches, observing no large difference down to 25 μm. Moreover, the effect of the charge sharing between neighboring strips on the spatial resolution has been quantified by measuring the Point Spread Function (PSF) of the system for the different pitches

  16. Contrast-enhanced spectral mammography based on a photon-counting detector: quantitative accuracy and radiation dose

    Science.gov (United States)

    Lee, Seungwan; Kang, Sooncheol; Eom, Jisoo

    2017-03-01

    Contrast-enhanced mammography has been used to demonstrate functional information about a breast tumor by injecting contrast agents. However, a conventional technique with a single exposure degrades the efficiency of tumor detection due to structure overlapping. Dual-energy techniques with energy-integrating detectors (EIDs) also cause an increase of radiation dose and an inaccuracy of material decomposition due to the limitations of EIDs. On the other hands, spectral mammography with photon-counting detectors (PCDs) is able to resolve the issues induced by the conventional technique and EIDs using their energy-discrimination capabilities. In this study, the contrast-enhanced spectral mammography based on a PCD was implemented by using a polychromatic dual-energy model, and the proposed technique was compared with the dual-energy technique with an EID in terms of quantitative accuracy and radiation dose. The results showed that the proposed technique improved the quantitative accuracy as well as reduced radiation dose comparing to the dual-energy technique with an EID. The quantitative accuracy of the contrast-enhanced spectral mammography based on a PCD was slightly improved as a function of radiation dose. Therefore, the contrast-enhanced spectral mammography based on a PCD is able to provide useful information for detecting breast tumors and improving diagnostic accuracy.

  17. Improving the counting efficiency in time-correlated single photon counting experiments by dead-time optimization

    Energy Technology Data Exchange (ETDEWEB)

    Peronio, P.; Acconcia, G.; Rech, I.; Ghioni, M. [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2015-11-15

    Time-Correlated Single Photon Counting (TCSPC) has been long recognized as the most sensitive method for fluorescence lifetime measurements, but often requiring “long” data acquisition times. This drawback is related to the limited counting capability of the TCSPC technique, due to pile-up and counting loss effects. In recent years, multi-module TCSPC systems have been introduced to overcome this issue. Splitting the light into several detectors connected to independent TCSPC modules proportionally increases the counting capability. Of course, multi-module operation also increases the system cost and can cause space and power supply problems. In this paper, we propose an alternative approach based on a new detector and processing electronics designed to reduce the overall system dead time, thus enabling efficient photon collection at high excitation rate. We present a fast active quenching circuit for single-photon avalanche diodes which features a minimum dead time of 12.4 ns. We also introduce a new Time-to-Amplitude Converter (TAC) able to attain extra-short dead time thanks to the combination of a scalable array of monolithically integrated TACs and a sequential router. The fast TAC (F-TAC) makes it possible to operate the system towards the upper limit of detector count rate capability (∼80 Mcps) with reduced pile-up losses, addressing one of the historic criticisms of TCSPC. Preliminary measurements on the F-TAC are presented and discussed.

  18. High-performance integrated pick-up circuit for SPAD arrays in time-correlated single photon counting

    Science.gov (United States)

    Acconcia, Giulia; Cominelli, Alessandro; Peronio, Pietro; Rech, Ivan; Ghioni, Massimo

    2017-05-01

    The analysis of optical signals by means of Single Photon Avalanche Diodes (SPADs) has been subject to a widespread interest in recent years. The development of multichannel high-performance Time Correlated Single Photon Counting (TCSPC) acquisition systems has undergone a fast trend. Concerning the detector performance, best in class results have been obtained resorting to custom technologies leading also to a strong dependence of the detector timing jitter from the threshold used to determine the onset of the photogenerated current flow. In this scenario, the avalanche current pick-up circuit plays a key role in determining the timing performance of the TCSPC acquisition system, especially with a large array of SPAD detectors because of electrical crosstalk issues. We developed a new current pick-up circuit based on a transimpedance amplifier structure able to extract the timing information from a 50-μm-diameter custom technology SPAD with a state-of-art timing jitter as low as 32ps and suitable to be exploited with SPAD arrays. In this paper we discuss the key features of this structure and we present a new version of the pick-up circuit that also provides quenching capabilities in order to minimize the number of interconnections required, an aspect that becomes more and more crucial in densely integrated systems.

  19. HEPS-BPIX, a single photon counting pixel detector with a high frame rate for the HEPS project

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Wei, E-mail: weiw@ihep.ac.cn [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); State Key Laboratory of Particle Detection and Electronics, Beijing 100049 (China); Zhang, Jie; Ning, Zhe; Lu, Yunpeng; Fan, Lei; Li, Huaishen; Jiang, Xiaoshan; Lan, Allan K.; Ouyang, Qun; Wang, Zheng; Zhu, Kejun; Chen, Yuanbo [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); State Key Laboratory of Particle Detection and Electronics, Beijing 100049 (China); Liu, Peng [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2016-11-01

    China's next generation light source, named the High Energy Photon Source (HEPS), is currently under construction. HEPS-BPIX (HEPS-Beijing PIXel) is a dedicated pixel readout chip that operates in single photon counting mode for X-ray applications in HEPS. Designed using CMOS 0.13 µm technology, the chip contains a matrix of 104×72 pixels. Each pixel measures 150 µm×150 µm and has a counting depth of 20 bits. A bump-bonded prototyping detector module with a 300-µm thick silicon sensor was tested in the beamline of Beijing Synchrotron Radiation Facility. A fast stream of X-ray images was demonstrated, and a frame rate of 1.2 kHz was proven, with a negligible dead time. The test results showed an equivalent noise charge of 115 e{sup −} rms after bump bonding and a threshold dispersion of 55 e{sup −} rms after calibration.

  20. UVSiPM: A light detector instrument based on a SiPM sensor working in single photon counting

    Energy Technology Data Exchange (ETDEWEB)

    Sottile, G.; Russo, F.; Agnetta, G. [Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, IASF-Pa/INAF, Palermo (Italy); Belluso, M.; Billotta, S. [Osservatorio Astrofisico di Catania, OACT/INAF, Catania (Italy); Biondo, B. [Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, IASF-Pa/INAF, Palermo (Italy); Bonanno, G. [Osservatorio Astrofisico di Catania, OACT/INAF, Catania (Italy); Catalano, O.; Giarrusso, S. [Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, IASF-Pa/INAF, Palermo (Italy); Grillo, A. [Osservatorio Astrofisico di Catania, OACT/INAF, Catania (Italy); Impiombato, D.; La Rosa, G.; Maccarone, M.C.; Mangano, A. [Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, IASF-Pa/INAF, Palermo (Italy); Marano, D. [Osservatorio Astrofisico di Catania, OACT/INAF, Catania (Italy); Mineo, T.; Segreto, A.; Strazzeri, E. [Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, IASF-Pa/INAF, Palermo (Italy); Timpanaro, M.C. [Osservatorio Astrofisico di Catania, OACT/INAF, Catania (Italy)

    2013-06-15

    UVSiPM is a light detector designed to measure the intensity of electromagnetic radiation in the 320–900 nm wavelength range. It has been developed in the framework of the ASTRI project whose main goal is the design and construction of an end-to-end Small Size class Telescope prototype for the Cherenkov Telescope Array. The UVSiPM instrument is composed by a multipixel Silicon Photo-Multiplier detector unit coupled to an electronic chain working in single photon counting mode with 10 nanosecond double pulse resolution, and by a disk emulator interface card for computer connection. The detector unit of UVSiPM is of the same kind as the ones forming the camera at the focal plane of the ASTRI prototype. Eventually, the UVSiPM instrument can be equipped with a collimator to regulate its angular aperture. UVSiPM, with its peculiar characteristics, will permit to perform several measurements both in lab and on field, allowing the absolute calibration of the ASTRI prototype.

  1. Performance of a single photon counting microstrip detector for strip pitches down to 10 μm

    Science.gov (United States)

    Bergamaschi, A.; Broennimann, Ch.; Dinapoli, R.; Eikenberry, E.; Gozzo, F.; Henrich, B.; Kobas, M.; Kraft, P.; Patterson, B.; Schmitt, B.

    2008-06-01

    The MYTHEN detector is a one-dimensional microstrip detector with single photon counting readout optimized for time resolved powder diffraction experiments at the Swiss Light Source (SLS). The system has been successfully tested for many different synchrotron radiation applications including phase contrast and tomographic imaging, small angle scattering, diffraction and time resolved pump and probe experiments for X-ray energies down to 5 keV and counting rate up to 3 MHz. The frontend electronics is designed in order to be coupled to 50 μm pitch microstrip sensors but some interest in enhancing the spatial resolution is arising for imaging and powder diffraction experiments. A test structure with strip pitches in the range 10-50 μm has been tested and the gain and noise on the readout electronics have been measured for the different strip pitches, observing no large difference down to 25 μm. Moreover, the effect of the charge sharing between neighboring strips on the spatial resolution has been quantified by measuring the Point Spread Function (PSF) of the system for the different pitches.

  2. Near-Infrared Photon-Counting Camera for High-Sensitivity Observations

    Science.gov (United States)

    Jurkovic, Michael

    2012-01-01

    The dark current of a transferred-electron photocathode with an InGaAs absorber, responsive over the 0.9-to-1.7- micron range, must be reduced to an ultralow level suitable for low signal spectral astrophysical measurements by lowering the temperature of the sensor incorporating the cathode. However, photocathode quantum efficiency (QE) is known to reduce to zero at such low temperatures. Moreover, it has not been demonstrated that the target dark current can be reached at any temperature using existing photocathodes. Changes in the transferred-electron photocathode epistructure (with an In- GaAs absorber lattice-matched to InP and exhibiting responsivity over the 0.9- to-1.7- m range) and fabrication processes were developed and implemented that resulted in a demonstrated >13x reduction in dark current at -40 C while retaining >95% of the approximately equal to 25% saturated room-temperature QE. Further testing at lower temperature is needed to confirm a >25 C predicted reduction in cooling required to achieve an ultralow dark-current target suitable for faint spectral astronomical observations that are not otherwise possible. This reduction in dark current makes it possible to increase the integration time of the imaging sensor, thus enabling a much higher near-infrared (NIR) sensitivity than is possible with current technology. As a result, extremely faint phenomena and NIR signals emitted from distant celestial objects can be now observed and imaged (such as the dynamics of redshifting galaxies, and spectral measurements on extra-solar planets in search of water and bio-markers) that were not previously possible. In addition, the enhanced NIR sensitivity also directly benefits other NIR imaging applications, including drug and bomb detection, stand-off detection of improvised explosive devices (IED's), Raman spectroscopy and microscopy for life/physical science applications, and semiconductor product defect detection.

  3. Simulation results for PLATO: a prototype hybrid X-ray photon counting detector with a low energy threshold for fusion plasma diagnostics

    International Nuclear Information System (INIS)

    Habib, A.; Menouni, M.; Pangaud, P.; Morel, C.; Fenzi, C.; Colledani, G.; Moureau, G.; Escarguel, A.

    2017-01-01

    PLATO is a prototype hybrid X-ray photon counting detector that has been designed to meet the specifications for plasma diagnostics for the WEST tokamak platform (Tungsten (W) Environment in Steady-state Tokamak) in southern France, with potential perspectives for ITER. PLATO represents a customized solution that fulfills high sensitivity, low dispersion and high photon counting rate. The PLATO prototype matrix is composed of 16 × 18 pixels with a 70 μm pixel pitch. New techniques have been used in analog sensitive blocks to minimize noise coupling through supply rails and substrate, and to suppress threshold dispersion across the matrix. The PLATO ASIC is designed in CMOS 0.13 μm technology and was submitted for a fabrication run in June 2016. The chip is designed to be bump-bonded to a silicon sensor. This paper presents pixel architecture as well as simulation results while highlighting novel solutions.

  4. Characteristic performance evaluation of a photon counting Si strip detector for low dose spectral breast CT imaging

    Science.gov (United States)

    Cho, Hyo-Min; Barber, William C.; Ding, Huanjun; Iwanczyk, Jan S.; Molloi, Sabee

    2014-01-01

    Purpose: The possible clinical applications which can be performed using a newly developed detector depend on the detector's characteristic performance in a number of metrics including the dynamic range, resolution, uniformity, and stability. The authors have evaluated a prototype energy resolved fast photon counting x-ray detector based on a silicon (Si) strip sensor used in an edge-on geometry with an application specific integrated circuit to record the number of x-rays and their energies at high flux and fast frame rates. The investigated detector was integrated with a dedicated breast spectral computed tomography (CT) system to make use of the detector's high spatial and energy resolution and low noise performance under conditions suitable for clinical breast imaging. The aim of this article is to investigate the intrinsic characteristics of the detector, in terms of maximum output count rate, spatial and energy resolution, and noise performance of the imaging system. Methods: The maximum output count rate was obtained with a 50 W x-ray tube with a maximum continuous output of 50 kVp at 1.0 mA. A109Cd source, with a characteristic x-ray peak at 22 keV from Ag, was used to measure the energy resolution of the detector. The axial plane modulation transfer function (MTF) was measured using a 67 μm diameter tungsten wire. The two-dimensional (2D) noise power spectrum (NPS) was measured using flat field images and noise equivalent quanta (NEQ) were calculated using the MTF and NPS results. The image quality parameters were studied as a function of various radiation doses and reconstruction filters. The one-dimensional (1D) NPS was used to investigate the effect of electronic noise elimination by varying the minimum energy threshold. Results: A maximum output count rate of 100 million counts per second per square millimeter (cps/mm2) has been obtained (1 million cps per 100 × 100 μm pixel). The electrical noise floor was less than 4 keV. The energy resolution

  5. Smart dosimetry by pattern recognition using a single photon counting detector system in time over threshold mode

    International Nuclear Information System (INIS)

    Reza, S; Wong, W S; Fröjdh, E; Norlin, B; Fröjdh, C; Thungström, G; Thim, J

    2012-01-01

    The function of a dosimeter is to determine the absorbed dose of radiation, for those cases in which, generally, the particular type of radiation is already known. Lately, a number of applications have emerged in which all kinds of radiation are absorbed and are sorted by pattern recognition, such as the Medipix2 application in [1]. This form of smart dosimetry enables measurements where not only the total dosage is measured, but also the contributions of different types of radiation impacting upon the detector surface. Furthermore, the use of a photon counting system, where the energy deposition can be measured in each individual pixel, ensures measurements with a high degree of accuracy in relation to the pattern recognition. In this article a Timepix [2] detector system has been used in the creation of a smart dosimeter for Alpha, Beta and Gamma radiation. When a radioactive particle hits the detector surface it generates charge clusters and those impacting upon the detector surface are read out and image processing algorithms are then used to classify each charge cluster. The individual clusters are calculated and as a result, the dosage for each type of radiation is given. In some cases, several particles can impact in roughly the same place, forming overlapping clusters. In order to handle this problem, a cluster separation method has been added to the pattern recognition algorithm. When the clusters have been separated, they are classified by shape and sorted into the correct type of radiation. The algorithms and methods used in this dosimeter have been developed so as to be simple and computationally effective, in order to enable implementation on a portable device.

  6. Testing multistage gain and offset trimming in a single photon counting IC with a charge sharing elimination algorithm

    International Nuclear Information System (INIS)

    Krzyżanowska, A.; Gryboś, P.; Szczygieł, R.; Maj, P.

    2015-01-01

    Designing a hybrid pixel detector readout electronics operating in a single photon counting mode is a very challenging process, where many main parameters are optimized in parallel (e.g. gain, noise, and threshold dispersion). Additional requirements for a smaller pixel size with extended functionality push designers to use new deep sub-micron technologies. Minimizing the channel size is possible, however, with a decreased pixel size, the charge sharing effect becomes a more important issue. To overcome this problem, we designed an integrated circuit prototype produced in CMOS 40 nm technology, which has an extended functionality of a single pixel. A C8P1 algorithm for the charge sharing effect compensation was implemented. In the algorithm's first stage the charge is rebuilt in a signal rebuilt hub fed by the CSA (charge sensitive amplifier) outputs from four neighbouring pixels. Then, the pixel with the biggest amount of charge is chosen, after a comparison with all the adjacent ones. In order to process the data in such a complicated way, a certain architecture of a single channel was proposed, which allows for: ⋅ processing the signal with the possibility of total charge reconstruction (by connecting with the adjacent pixels), ⋅ a comparison of certain pixel amplitude to its 8 neighbours, ⋅ the extended testability of each block inside the channel to measure CSA gain dispersion, shaper gain dispersion, threshold dispersion (including the simultaneous generation of different pulse amplitudes from different pixels), ⋅ trimming all the necessary blocks for proper operation. We present a solution for multistage gain and offset trimming implemented in the IC prototype. It allows for minimization of the total charge extraction errors, minimization of threshold dispersion in the pixel matrix and minimization of errors of comparison of certain pixel pulse amplitudes with all its neighbours. The detailed architecture of a single channel is presented

  7. A fast and high-sensitive dual-wavelength diffuse optical tomography system using digital lock-in photon-counting technique

    Science.gov (United States)

    Chen, Weiting; Yi, Xi; Zhao, Huijuan; Gao, Feng

    2014-09-01

    We presented a novel dual-wavelength diffuse optical imaging system which can perform 2-D or 3-D imaging fast and high-sensitively for monitoring the dynamic change of optical parameters. A newly proposed lock-in photon-counting detection method was adopted for week optical signal collection, which brought in excellent property as well as simplified geometry. Fundamental principles of the lock-in photon-counting detection were elaborately demonstrated, and the feasibility was strictly verified by the linearity experiment. Systemic performance of the prototype set up was experimentally accessed, including stray light rejection and inherent interference. Results showed that the system possessed superior anti-interference capability (under 0.58% in darkroom) compared with traditional photon-counting detection, and the crosstalk between two wavelengths was lower than 2.28%. For comprehensive assessment, 2-D phantom experiments towards relatively large dimension model (diameter of 4cm) were conducted. Different absorption targets were imaged to investigate detection sensitivity. Reconstruction image under all conditions was exciting, with a desirable SNR. Study on image quality v.s. integration time put forward a new method for accessing higher SNR with the sacrifice of measuring speed. In summary, the newly developed system showed great potential in promoting detection sensitivity as well as measuring speed. This will make substantial progress in dynamically tracking the blood concentration distribution in many clinical areas, such as small animal disease modeling, human brain activity research and thick tissues (for example, breast) diagnosis.

  8. Direct and indirect signal detection of 122 keV photons with a novel detector combining a pnCCD and a CsI(Tl) scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Schlosser, D.M., E-mail: dieter.schlosser@pnsensor.de [PNSensor GmbH, Sckellstraße 3, 81667 München (Germany); Huth, M.; Hartmann, R. [PNSensor GmbH, Sckellstraße 3, 81667 München (Germany); Abboud, A.; Send, S. [Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen (Germany); Conka-Nurdan, T. [Türkisch-Deutsche Universität, Sakinkaya Cad. 86, Beykoz, 34820 Istanbul (Turkey); Shokr, M.; Pietsch, U. [Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen (Germany); Strüder, L. [PNSensor GmbH, Sckellstraße 3, 81667 München (Germany); Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen (Germany)

    2016-01-01

    By combining a low noise fully depleted pnCCD detector with a CsI(Tl) scintillator, an energy-dispersive area detector can be realized with a high quantum efficiency (QE) in the range from below 1 keV to above 100 keV. In direct detection mode the pnCCD exhibits a relative energy resolution of 1% at 122 keV and spatial resolution of less than 75 µm, the pixel size of the pnCCD. In the indirect detection mode, i.e. conversion of the incoming X-rays in the scintillator, the measured energy resolution was about 9–13% at 122 keV, depending on the depth of interaction in the scintillator, while the position resolution, extracted with the help of simulations, was 30 µm only. We show simulated data for incident photons of 122 keV and compare the various interaction processes and relevant physical parameters to experimental results obtained with a radioactive {sup 57}Co source. - Highlights: • Position and energy resolving pnCCD+CsI(Tl) detector for energies from 1-150 keV • Detection in the pnCCD (122keV): 1% energy and <75µm spatial resolution • Detection in the scintillator (122keV): 9-12% energy and ~30µm spatial resolution.

  9. EXCALIBUR: a small-pixel photon counting area detector for coherent X-ray diffraction - Front-end design, fabrication and characterisation

    Science.gov (United States)

    Marchal, J.; Horswell, I.; Willis, B.; Plackett, R.; Gimenez, E. N.; Spiers, J.; Ballard, D.; Booker, P.; Thompson, J. A.; Gibbons, P.; Burge, S. R.; Nicholls, T.; Lipp, J.; Tartoni, N.

    2013-03-01

    Coherent X-ray diffraction experiments on synchrotron X-ray beamlines require detectors with high spatial resolution and large detection area. The read-out chip developed by the MEDIPIX3 collaboration offers a small pixel size of 55 microns resulting in a very high spatial resolution when coupled to a direct X-ray conversion segmented silicon sensor. MEDIPIX3 assemblies present also the advantages of hybrid pixel detectors working in single photon counting mode: noiseless imaging, large dynamic range, extremely high frame rate. The EXCALIBUR detector is under development for the X-ray Coherence and Imaging Beamline I13 of the Diamond Light Source. This new detector consists of three modules, each with 16 MEDIPIX3 chips which can be read-out at 100 frames per second in continuous mode or 1000 frames per second in burst mode. In each module, the sensor is a large single silicon die covering 2 rows of 8 individual MEDIPIX3 read-out chips and provides a continuous active detection region within a module. Each module includes 1 million solder bumps connecting the 55 microns pixels of the silicon sensor to the 55 microns pixels of the 16 MEDIPIX3 read-out chips. The detection area of the 3-module EXCALIBUR detector is 115 mm × 100 mm with a small 6.8 mm wide inactive region between modules. Each detector module is connected to 2 FPGA read-out boards via a flexi-rigid circuit to allow a fully parallel read-out of the 16 MEDIPIX3 chips. The 6 FPGA read-out boards used in the EXCALIBUR detector are interfaced to 6 computing nodes via 10Gbit/s fibre-optic links to maintain the very high frame-rate capability. The standard suite of EPICS control software is used to operate the detector and to integrate it with the Diamond Light Source beamline software environment. This article describes the design, fabrication and characterisation of the MEDIPIX3-based modules composing the EXCALIBUR detector.

  10. EXCALIBUR: a small-pixel photon counting area detector for coherent X-ray diffraction - Front-end design, fabrication and characterisation

    International Nuclear Information System (INIS)

    Marchal, J; Horswell, I; Willis, B; Plackett, R; Gimenez, E N; Spiers, J; Thompson, J A; Gibbons, P; Tartoni, N; Ballard, D; Booker, P; Burge, S R; Nicholls, T; Lipp, J

    2013-01-01

    Coherent X-ray diffraction experiments on synchrotron X-ray beamlines require detectors with high spatial resolution and large detection area. The read-out chip developed by the MEDIPIX3 collaboration offers a small pixel size of 55 microns resulting in a very high spatial resolution when coupled to a direct X-ray conversion segmented silicon sensor. MEDIPIX3 assemblies present also the advantages of hybrid pixel detectors working in single photon counting mode: noiseless imaging, large dynamic range, extremely high frame rate. The EXCALIBUR detector is under development for the X-ray Coherence and Imaging Beamline I13 of the Diamond Light Source. This new detector consists of three modules, each with 16 MEDIPIX3 chips which can be read-out at 100 frames per second in continuous mode or 1000 frames per second in burst mode. In each module, the sensor is a large single silicon die covering 2 rows of 8 individual MEDIPIX3 read-out chips and provides a continuous active detection region within a module. Each module includes 1 million solder bumps connecting the 55 microns pixels of the silicon sensor to the 55 microns pixels of the 16 MEDIPIX3 read-out chips. The detection area of the 3-module EXCALIBUR detector is 115 mm × 100 mm with a small 6.8 mm wide inactive region between modules. Each detector module is connected to 2 FPGA read-out boards via a flexi-rigid circuit to allow a fully parallel read-out of the 16 MEDIPIX3 chips. The 6 FPGA read-out boards used in the EXCALIBUR detector are interfaced to 6 computing nodes via 10Gbit/s fibre-optic links to maintain the very high frame-rate capability. The standard suite of EPICS control software is used to operate the detector and to integrate it with the Diamond Light Source beamline software environment. This article describes the design, fabrication and characterisation of the MEDIPIX3-based modules composing the EXCALIBUR detector.

  11. Scintillation Counters

    Science.gov (United States)

    Bell, Zane W.

    Scintillators find wide use in radiation detection as the detecting medium for gamma/X-rays, and charged and neutral particles. Since the first notice in 1895 by Roentgen of the production of light by X-rays on a barium platinocyanide screen, and Thomas Edison's work over the following 2 years resulting in the discovery of calcium tungstate as a superior fluoroscopy screen, much research and experimentation have been undertaken to discover and elucidate the properties of new scintillators. Scintillators with high density and high atomic number are prized for the detection of gamma rays above 1 MeV; lower atomic number, lower-density materials find use for detecting beta particles and heavy charged particles; hydrogenous scintillators find use in fast-neutron detection; and boron-, lithium-, and gadolinium-containing scintillators are used for slow-neutron detection. This chapter provides the practitioner with an overview of the general characteristics of scintillators, including the variation of probability of interaction with density and atomic number, the characteristics of the light pulse, a list and characteristics of commonly available scintillators and their approximate cost, and recommendations regarding the choice of material for a few specific applications. This chapter does not pretend to present an exhaustive list of scintillators and applications.

  12. TH-CD-207B-07: Noise Modeling of Single Photon Avalanche Diode (SPAD) for Photon Counting CT Applications

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Z; Zheng, X; Deen, J; Peng, H [McMaster University, Hamilton, ON (Canada); Xing, L [Stanford University School of Medicine, Stanford, CA (United States)

    2016-06-15

    Purpose: Silicon photomultiplier (SiPM) has recently emerged as a promising photodetector for biomedical imaging applications. Due to its high multiplication gain (comparable to PMT), fast timing, low cost and compactness, it is considered a good candidate for photon counting CT. Dark noise is a limiting factor which impacts both energy resolution and detection dynamic range. Our goal is to develop a comprehensive model for noise sources for SiPM sensors. Methods: The physical parameters used in this work were based upon a test SPAD fabricated in 130nm CMOS process. The SPAD uses an n+/p-well junction, which is isolated from the p-substrate by a deep n-well junction. Inter-avalanche time measurement was used to record the time interval between two adjacent avalanche pulses. After collecting 1×106 counts, the histogram was obtained and multiple exponential fitting process was used to extract the lifetime associated with the traps within the bandgap. Results: At room temperature, the breakdown voltage of the SPAD is ∼11.4V and shows a temperature coefficient of 7.7mV/°C. The dark noise of SPAD increases with both the excess biasing voltage and temperature. The primary dark counts from the model were validated against the measurement results. A maximum relative error of 8.7% is observed at 20 °C with an excess voltage of 0.5V. The probabilities of after-pulsing are found to be dependent of both temperature and excess voltage. With 0.5V excess voltage, the after-pulsing probability is 63.5% at - 30 °C and drops to ∼6.6% at 40 °C. Conclusion: A comprehensive noise model for SPAD sensor was proposed. The model takes into account of static, dynamic and statistical behavior of SPADs. We believe that this is the first SPAD circuit simulation model that includes the band-to-band tunneling dark noise contribution and temporal dependence of the after-pulsing probability.

  13. Every photon counts: improving low, mid, and high-spatial frequency errors on astronomical optics and materials with MRF

    Science.gov (United States)

    Maloney, Chris; Lormeau, Jean Pierre; Dumas, Paul

    2016-07-01

    Many astronomical sensing applications operate in low-light conditions; for these applications every photon counts. Controlling mid-spatial frequencies and surface roughness on astronomical optics are critical for mitigating scattering effects such as flare and energy loss. By improving these two frequency regimes higher contrast images can be collected with improved efficiency. Classically, Magnetorheological Finishing (MRF) has offered an optical fabrication technique to correct low order errors as well has quilting/print-through errors left over in light-weighted optics from conventional polishing techniques. MRF is a deterministic, sub-aperture polishing process that has been used to improve figure on an ever expanding assortment of optical geometries, such as planos, spheres, on and off axis aspheres, primary mirrors and freeform optics. Precision optics are routinely manufactured by this technology with sizes ranging from 5-2,000mm in diameter. MRF can be used for form corrections; turning a sphere into an asphere or free form, but more commonly for figure corrections achieving figure errors as low as 1nm RMS while using careful metrology setups. Recent advancements in MRF technology have improved the polishing performance expected for astronomical optics in low, mid and high spatial frequency regimes. Deterministic figure correction with MRF is compatible with most materials, including some recent examples on Silicon Carbide and RSA905 Aluminum. MRF also has the ability to produce `perfectly-bad' compensating surfaces, which may be used to compensate for measured or modeled optical deformation from sources such as gravity or mounting. In addition, recent advances in MRF technology allow for corrections of mid-spatial wavelengths as small as 1mm simultaneously with form error correction. Efficient midspatial frequency corrections make use of optimized process conditions including raster polishing in combination with a small tool size. Furthermore, a novel MRF

  14. Scintillation camera

    International Nuclear Information System (INIS)

    Zioni, J.; Klein, Y.; Inbar, D.

    1975-01-01

    The scintillation camera is to make pictures of the density distribution of radiation fields created by the injection or administration radioactive medicaments into the body of the patient. It contains a scintillation crystal, several photomultipliers and computer circuits to obtain an analytical function at the exits of the photomultiplier which is dependent on the position of the scintillations at the time in the crystal. The scintillation crystal is flat and spatially corresponds to the production site of radiation. The photomultipliers form a pattern whose basic form consists of at least three photomultipliers. They are assigned to at least two crossing parallel series groups where a vertical running reference axis in the crystal plane belongs to each series group. The computer circuits are each assigned to a reference axis. Each series of a series group assigned to one of the reference axes in the computer circuit has an adder to produce a scintillation dependent series signal. Furthermore, the projection of the scintillation on this reference axis is calculated. A series signal is used for this which originates from a series chosen from two neighbouring photomultiplier series of this group. The scintillation must have appeared between these chosen series. They are termed as basic series. The photomultiplier can be arranged hexagonally or rectangularly. (GG/LH) [de

  15. Timing performance of ZnO:Ga nanopowder composite scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Turtos, Rosana M. [Universita degli Studi di Milano-Bicocca, Milano (Italy); Gundacker, Stefan; Lucchini, Marco T.; Lecoq, Paul; Auffray, Etiennette [CERN, Geneva (Switzerland); Prochazkova, Lenka; Cuba, Vaclav [Czech Technical University, Faculty of Nuclear Sciences and Physical Engineering, Prague (Czech Republic); Buresova, Hana [Nuvia a.s, Kralupy nad Vltavou (Czech Republic); Mrazek, Jan [Institute of Photonics and Electronics AS CR, Prague (Czech Republic); Nikl, Martin [Institute of Physics of the AS CR, Prague (Czech Republic)

    2016-11-15

    The implementation of nanocrystal-based composite scintillators as a new generation of ultrafast particle detectors is explored using ZnO:Ga nanopowder. Samples are characterized with a spectral-time resolved photon counting system and pulsed X-rays, followed by coincidence time resolution (CTR) measurements under 511 keV gamma excitation. Results are comparable to CTR values obtained using bulk inorganic scintillators. Bringing the ZnO:Ga nanocrystal's timing performance to radiation detectors could pave the research path towards sub-20 ps time resolution as shown in this contribution. However, an efficiency boost when placing nanopowders in a transparent host constitutes the main challenge in order to benefit from sub-nanosecond recombination times. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Radiation hardness tests and characterization of the CLARO-CMOS, a low power and fast single-photon counting ASIC in 0.35 micron CMOS technology

    International Nuclear Information System (INIS)

    Fiorini, M.; Andreotti, M.; Baldini, W.; Calabrese, R.; Carniti, P.; Cassina, L.; Cotta Ramusino, A.; Giachero, A.; Gotti, C.; Luppi, E.; Maino, M.; Malaguti, R.; Pessina, G.; Tomassetti, L.

    2014-01-01

    The CLARO-CMOS is a prototype ASIC that allows fast photon counting with 5 ns peaking time, a recovery time to baseline smaller than 25 ns, and a power consumption of less than 1 mW per channel. This chip is capable of single-photon counting with multi-anode photomultipliers and finds applications also in the read-out of silicon photomultipliers and microchannel plates. The prototype is realized in AMS 0.35 micron CMOS technology. In the LHCb RICH environment, assuming 10 years of operation at the nominal luminosity expected after the upgrade in Long Shutdown 2 (LS2), the ASIC must withstand a total fluence of about 6×10 12 1 MeV n eq /cm 2 and a total ionizing dose of 400 krad. A systematic evaluation of the radiation effects on the CLARO-CMOS performance is therefore crucial to ensure long term stability of the electronics front-end. The results of multi-step irradiation tests with neutrons and X-rays up to the fluence of 10 14 cm −2 and a dose of 4 Mrad, respectively, are presented, including measurement of single event effects during irradiation and chip performance evaluation before and after each irradiation step. - Highlights: • CLARO chip capable of single-photon counting with 5 ns peaking time. • Chip irradiated up to very high neutron, proton and X-rays fluences, as expected for upgraded LHCb RICH detectors. • No significant performance degradation is observed after irradiation

  17. Ideal-observer detectability in photon-counting differential phase-contrast imaging using a linear-systems approach

    International Nuclear Information System (INIS)

    Fredenberg, Erik; Danielsson, Mats; Stayman, J. Webster; Siewerdsen, Jeffrey H.; Åslund, Magnus

    2012-01-01

    Purpose: To provide a cascaded-systems framework based on the noise-power spectrum (NPS), modulation transfer function (MTF), and noise-equivalent number of quanta (NEQ) for quantitative evaluation of differential phase-contrast imaging (Talbot interferometry) in relation to conventional absorption contrast under equal-dose, equal-geometry, and, to some extent, equal-photon-economy constraints. The focus is a geometry for photon-counting mammography. Methods: Phase-contrast imaging is a promising technology that may emerge as an alternative or adjunct to conventional absorption contrast. In particular, phase contrast may increase the signal-difference-to-noise ratio compared to absorption contrast because the difference in phase shift between soft-tissue structures is often substantially larger than the absorption difference. We have developed a comprehensive cascaded-systems framework to investigate Talbot interferometry, which is a technique for differential phase-contrast imaging. Analytical expressions for the MTF and NPS were derived to calculate the NEQ and a task-specific ideal-observer detectability index under assumptions of linearity and shift invariance. Talbot interferometry was compared to absorption contrast at equal dose, and using either a plane wave or a spherical wave in a conceivable mammography geometry. The impact of source size and spectrum bandwidth was included in the framework, and the trade-off with photon economy was investigated in some detail. Wave-propagation simulations were used to verify the analytical expressions and to generate example images. Results: Talbot interferometry inherently detects the differential of the phase, which led to a maximum in NEQ at high spatial frequencies, whereas the absorption-contrast NEQ decreased monotonically with frequency. Further, phase contrast detects differences in density rather than atomic number, and the optimal imaging energy was found to be a factor of 1.7 higher than for absorption

  18. Ideal-observer detectability in photon-counting differential phase-contrast imaging using a linear-systems approach

    Energy Technology Data Exchange (ETDEWEB)

    Fredenberg, Erik; Danielsson, Mats; Stayman, J. Webster; Siewerdsen, Jeffrey H.; Aslund, Magnus [Research and Development, Philips Women' s Healthcare, Smidesvaegen 5, SE-171 41 Solna, Sweden and Department of Physics, Royal Institute of Technology, AlbaNova, SE-106 91 Stockholm (Sweden); Department of Physics, Royal Institute of Technology, AlbaNova, SE-106 91 Stockholm (Sweden); Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Department of Biomedical Engineering and Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21205 (United States); Research and Development, Philips Women' s Healthcare, Smidesvaegen 5, SE-171 41 Solna (Sweden)

    2012-09-15

    Purpose: To provide a cascaded-systems framework based on the noise-power spectrum (NPS), modulation transfer function (MTF), and noise-equivalent number of quanta (NEQ) for quantitative evaluation of differential phase-contrast imaging (Talbot interferometry) in relation to conventional absorption contrast under equal-dose, equal-geometry, and, to some extent, equal-photon-economy constraints. The focus is a geometry for photon-counting mammography. Methods: Phase-contrast imaging is a promising technology that may emerge as an alternative or adjunct to conventional absorption contrast. In particular, phase contrast may increase the signal-difference-to-noise ratio compared to absorption contrast because the difference in phase shift between soft-tissue structures is often substantially larger than the absorption difference. We have developed a comprehensive cascaded-systems framework to investigate Talbot interferometry, which is a technique for differential phase-contrast imaging. Analytical expressions for the MTF and NPS were derived to calculate the NEQ and a task-specific ideal-observer detectability index under assumptions of linearity and shift invariance. Talbot interferometry was compared to absorption contrast at equal dose, and using either a plane wave or a spherical wave in a conceivable mammography geometry. The impact of source size and spectrum bandwidth was included in the framework, and the trade-off with photon economy was investigated in some detail. Wave-propagation simulations were used to verify the analytical expressions and to generate example images. Results: Talbot interferometry inherently detects the differential of the phase, which led to a maximum in NEQ at high spatial frequencies, whereas the absorption-contrast NEQ decreased monotonically with frequency. Further, phase contrast detects differences in density rather than atomic number, and the optimal imaging energy was found to be a factor of 1.7 higher than for absorption

  19. Photon Counting Computed Tomography With Dedicated Sharp Convolution Kernels: Tapping the Potential of a New Technology for Stent Imaging.

    Science.gov (United States)

    von Spiczak, Jochen; Mannil, Manoj; Peters, Benjamin; Hickethier, Tilman; Baer, Matthias; Henning, André; Schmidt, Bernhard; Flohr, Thomas; Manka, Robert; Maintz, David; Alkadhi, Hatem

    2018-05-23

    The aims of this study were to assess the value of a dedicated sharp convolution kernel for photon counting detector (PCD) computed tomography (CT) for coronary stent imaging and to evaluate to which extent iterative reconstructions can compensate for potential increases in image noise. For this in vitro study, a phantom simulating coronary artery stenting was prepared. Eighteen different coronary stents were expanded in plastic tubes of 3 mm diameter. Tubes were filled with diluted contrast agent, sealed, and immersed in oil calibrated to an attenuation of -100 HU simulating epicardial fat. The phantom was scanned in a modified second generation 128-slice dual-source CT scanner (SOMATOM Definition Flash, Siemens Healthcare, Erlangen, Germany) equipped with both a conventional energy integrating detector and PCD. Image data were acquired using the PCD part of the scanner with 48 × 0.25 mm slices, a tube voltage of 100 kVp, and tube current-time product of 100 mAs. Images were reconstructed using a conventional convolution kernel for stent imaging with filtered back-projection (B46) and with sinogram-affirmed iterative reconstruction (SAFIRE) at level 3 (I463). For comparison, a dedicated sharp convolution kernel with filtered back-projection (D70) and SAFIRE level 3 (Q703) and level 5 (Q705) was used. The D70 and Q70 kernels were specifically designed for coronary stent imaging with PCD CT by optimizing the image modulation transfer function and the separation of contrast edges. Two independent, blinded readers evaluated subjective image quality (Likert scale 0-3, where 3 = excellent), in-stent diameter difference, in-stent attenuation difference, mathematically defined image sharpness, and noise of each reconstruction. Interreader reliability was calculated using Goodman and Kruskal's γ and intraclass correlation coefficients (ICCs). Differences in image quality were evaluated using a Wilcoxon signed-rank test. Differences in in-stent diameter difference, in

  20. Plastic scintillator

    International Nuclear Information System (INIS)

    Andreeshchev, E.A.; Kilin, S.F.; Kavyrzina, K.A.

    1978-01-01

    A plastic scintillator for ionizing radiation detectors with high time resolution is suggested. To decrease the scintillation pulse width and to maintain a high light yield, the 4 1 , 4 5 -dibromo-2 1 , 2 5 , 5 1 , 5 5 -tetramethyl-n-quinquiphenyl (Br 2 Me 4 Ph) in combination with n-terphenyl (Ph 3 ) or 2, 5-diphenyloxadiazol-1, 3, 4 (PPD) is used as a luminescent addition. Taking into consideration the results of a special study, it is shown, that the following ratio of ingradients is the optimum one: 3-4 mass% Ph 3 or 4-7 mas% PPD + 2-5 mass% Br 2 Me 4 Ph + + polymeric base. The suggested scintillator on the basis of polystyrene has the light yield of 0.23-0.26 arbitrary units and the scintillation pulse duration at half-height is 0.74-0.84 ns

  1. Near-field reflection backscattering apertureless optical microscopy: Application to spectroscopy experiments on opaque samples, comparison between lock-in and digital photon counting detection techniques

    International Nuclear Information System (INIS)

    Diziain, S.; Bijeon, J.-L.; Adam, P.-M.; Lamy de la Chapelle, M.; Thomas, B.; Deturche, R.; Royer, P.

    2007-01-01

    An apertureless scanning near-field optical microscope (ASNOM) in reflection backscattering configuration is designed to conduct spectroscopic experiments on opaque samples constituted of latex beads. The ASNOM proposed takes advantage of the depth-discrimination properties of confocal microscopes to efficiently extract the near-field optical signal. Given their importance in a spectroscopic experiment, we systematically compare the lock-in and synchronous photon counting detection methods. Some results of Rayleigh's scattering in the near field of the test samples are used to illustrate the possibilities of this technique for reflection backscattering spectroscopy

  2. High Throughput, High Yield Fabrication of High Quantum Efficiency Back-Illuminated Photon Counting, Far UV, UV, and Visible Detector Arrays

    Science.gov (United States)

    Nikzad, Shouleh; Hoenk, M. E.; Carver, A. G.; Jones, T. J.; Greer, F.; Hamden, E.; Goodsall, T.

    2013-01-01

    In this paper we discuss the high throughput end-to-end post fabrication processing of high performance delta-doped and superlattice-doped silicon imagers for UV, visible, and NIR applications. As an example, we present our results on far ultraviolet and ultraviolet quantum efficiency (QE) in a photon counting, detector array. We have improved the QE by nearly an order of magnitude over microchannel plates (MCPs) that are the state-of-the-art UV detectors for many NASA space missions as well as defense applications. These achievements are made possible by precision interface band engineering of Molecular Beam Epitaxy (MBE) and Atomic Layer Deposition (ALD).

  3. Effects of calibration methods on quantitative material decomposition in photon-counting spectral computed tomography using a maximum a posteriori estimator.

    Science.gov (United States)

    Curtis, Tyler E; Roeder, Ryan K

    2017-10-01

    Advances in photon-counting detectors have enabled quantitative material decomposition using multi-energy or spectral computed tomography (CT). Supervised methods for material decomposition utilize an estimated attenuation for each material of interest at each photon energy level, which must be calibrated based upon calculated or measured values for known compositions. Measurements using a calibration phantom can advantageously account for system-specific noise, but the effect of calibration methods on the material basis matrix and subsequent quantitative material decomposition has not been experimentally investigated. Therefore, the objective of this study was to investigate the influence of the range and number of contrast agent concentrations within a modular calibration phantom on the accuracy of quantitative material decomposition in the image domain. Gadolinium was chosen as a model contrast agent in imaging phantoms, which also contained bone tissue and water as negative controls. The maximum gadolinium concentration (30, 60, and 90 mM) and total number of concentrations (2, 4, and 7) were independently varied to systematically investigate effects of the material basis matrix and scaling factor calibration on the quantitative (root mean squared error, RMSE) and spatial (sensitivity and specificity) accuracy of material decomposition. Images of calibration and sample phantoms were acquired using a commercially available photon-counting spectral micro-CT system with five energy bins selected to normalize photon counts and leverage the contrast agent k-edge. Material decomposition of gadolinium, calcium, and water was performed for each calibration method using a maximum a posteriori estimator. Both the quantitative and spatial accuracy of material decomposition were most improved by using an increased maximum gadolinium concentration (range) in the basis matrix calibration; the effects of using a greater number of concentrations were relatively small in

  4. Near-field reflection backscattering apertureless optical microscopy: Application to spectroscopy experiments on opaque samples, comparison between lock-in and digital photon counting detection techniques

    Energy Technology Data Exchange (ETDEWEB)

    Diziain, S. [Institut Charles Delaunay, CNRS FRE 2848, Laboratoire de Nanotechnologie et d' Instrumentation Optique, Universite de technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes cedex (France); Bijeon, J.-L. [Institut Charles Delaunay, CNRS FRE 2848, Laboratoire de Nanotechnologie et d' Instrumentation Optique, Universite de technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes cedex (France)]. E-mail: bijeon@utt.fr; Adam, P.-M. [Institut Charles Delaunay, CNRS FRE 2848, Laboratoire de Nanotechnologie et d' Instrumentation Optique, Universite de technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes cedex (France); Lamy de la Chapelle, M. [Institut Charles Delaunay, CNRS FRE 2848, Laboratoire de Nanotechnologie et d' Instrumentation Optique, Universite de technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes cedex (France); Thomas, B. [Institut Charles Delaunay, CNRS FRE 2848, Laboratoire de Nanotechnologie et d' Instrumentation Optique, Universite de technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes cedex (France); Deturche, R. [Institut Charles Delaunay, CNRS FRE 2848, Laboratoire de Nanotechnologie et d' Instrumentation Optique, Universite de technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes cedex (France); Royer, P. [Institut Charles Delaunay, CNRS FRE 2848, Laboratoire de Nanotechnologie et d' Instrumentation Optique, Universite de technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes cedex (France)

    2007-01-15

    An apertureless scanning near-field optical microscope (ASNOM) in reflection backscattering configuration is designed to conduct spectroscopic experiments on opaque samples constituted of latex beads. The ASNOM proposed takes advantage of the depth-discrimination properties of confocal microscopes to efficiently extract the near-field optical signal. Given their importance in a spectroscopic experiment, we systematically compare the lock-in and synchronous photon counting detection methods. Some results of Rayleigh's scattering in the near field of the test samples are used to illustrate the possibilities of this technique for reflection backscattering spectroscopy.

  5. Cryogenic scintillators for rare events detection in the Edelweiss and EURECA experiments

    International Nuclear Information System (INIS)

    Verdier, M.A.

    2010-10-01

    The riddle of the dark matter in astrophysics could be solved by the detection of WIMPs (Weakly Interactive Massive Particles), particles that are predicted by supersymmetry. The direct detection of WIMPs requires a large mass of detectors, able to identify these particles in the background of natural radioactivity and cosmic rays. This thesis takes place within the framework of the EDELWEISS and the future EURECA experiments. These experiments use a technology based on two channel cryogenic detectors (bolometers), working at a few tens of mK. They are composed of crystals in which the energy deposited by particle interactions will produce a temperature increase (phonon signal), and where the ionization of the crystals results in either a charge or photon signal, depending on their nature. In order to broaden the range of targets for scintillating bolometers, we have built a setup to study the scintillation of crystals cooled down to 3 K. It is based on a cryostat with a compact optical geometry allowing enhanced light collection. Thanks to an individual photon counting technique and a statistical treatment of data, it allows us to measure the evolution of the the light yields and the decay time components between room temperature and 3 K. Thus this thesis presents the results obtained at 3 K on two well known room temperature crystals: BGO (Bi 4 Ge 3 O 12 ) and BaF 2 . We also study the luminescence properties of titanium sapphire (Ti:Al 2 O 3 ), under VUV excitation cooled down to 8 K. (author)

  6. Theoretical analysis of the effect of charge-sharing on the Detective Quantum Efficiency of single-photon counting segmented silicon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Marchal, J [Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom)], E-mail: julien.marchal@diamond.ac.uk

    2010-01-15

    A detector cascaded model is proposed to describe charge-sharing effect in single-photon counting segmented silicon detectors. Linear system theory is applied to this cascaded model in order to derive detector performance parameters such as large-area gain, presampling Modulation Transfer Function (MTF), Noise Power Spectrum (NPS) and Detective Quantum Efficiency (DQE) as a function of energy detection threshold. This theory is used to model one-dimensional detectors (i.e. strip detectors) where X-ray-generated charge can be shared between two sampling elements, but the concepts developed in this article can be generalized to two-dimensional arrays of detecting elements (i.e. pixels detectors). The zero-frequency DQE derived from this model is consistent with expressions reported in the literature using a different method. The ability of this model to simulate the effect of charge sharing on image quality in the spatial frequency domain is demonstrated by applying it to a hypothetical one-dimensional single-photon counting detector illuminated with a typical mammography spectrum.

  7. Fast-ICCD photography and gated photon counting measurements of blackbody emission from particulates generated in the KrF-laser ablation of BN and YBCO

    Energy Technology Data Exchange (ETDEWEB)

    Geohegan, D.B.

    1992-11-01

    Fast intensified CCD photography and gated photon counting following KrF-laser irradiation of YBCO and BN targets reveals the first observations of very weak emission from slow-moving ejecta up to 2 cm from the target and times extending to {approx}1.5 ms. Time-of-flight velocities inferred from the emission measurements indicate velocities (v {approximately} (0.45--1.2) {times} 10{sup 4} cm s{sup {minus}1}) comparable to those measured for the large particles which often accompany the pulsed laser deposition process. Gated photon counting is employed to obtain temporally resolved spectra of this weak emission. The spectral shape is characteristic of blackbody emission, which shifts to longer wavelengths as the particles cool during flight in vacuum. Estimates of the temperature of the particles are made based on the emissivity of a perfect blackbody and range from 2200 K to 3200 K for both BN and YBCO when irradiated at ({Phi}{sub 248} = 3.5 J cm{sup {minus}2} and 1.5 J cm{sup {minus}2}, respectively. The temperature decrease of the particles in vacuum is compared to a radiative cooling model which gives estimates of the initial surface temperature and radii of the particles.

  8. Precise material identification method based on a photon counting technique with correction of the beam hardening effect in X-ray spectra

    International Nuclear Information System (INIS)

    Kimoto, Natsumi; Hayashi, Hiroaki; Asahara, Takashi; Mihara, Yoshiki; Kanazawa, Yuki; Yamakawa, Tsutomu; Yamamoto, Shuichiro; Yamasaki, Masashi; Okada, Masahiro

    2017-01-01

    The aim of our study is to develop a novel material identification method based on a photon counting technique, in which the incident and penetrating X-ray spectra are analyzed. Dividing a 40 kV X-ray spectra into two energy regions, the corresponding linear attenuation coefficients are derived. We can identify the materials precisely using the relationship between atomic number and linear attenuation coefficient through the correction of the beam hardening effect of the X-ray spectra. - Highlights: • We propose a precise material identification method to be used as a photon counting system. • Beam hardening correction is important, even when the analysis is applied to the short energy regions in the X-ray spectrum. • Experiments using a single probe-type CdTe detector were performed, and Monte Carlo simulation was also carried out. • We described the applicability of our method for clinical diagnostic X-ray imaging in the near future.

  9. Method for determining the irradiation dose deposited in a scintillator by ionising radiation and associated device - WO 2013060745 A1

    International Nuclear Information System (INIS)

    2013-01-01

    The invention relates to a method for determining an irradiation dose deposited in a scintillator (5) by ionising radiation, said method comprising the steps of: irradiating the scintillator (5) for a pre-determined time; detecting an instant at which the scintillator (5) is excited, using a first photodetector (11); subsequently, detecting an instant at which a scintillation photon is received, using a second photodetector (14) operating in single photon counting mode; identifying each sequence formed by the detection of an excitation instant by the first photodetector (11) and the detection of a reception instant by the second photodetector (14) at a coincidence event; counting the number of coincidence events; and obtaining the irradiation dose deposited during the irradiation time as a function of the number of coincidence events counted and a pre-determined proportionality factor. (authors)

  10. Two-dimensional diced scintillator array for innovative, fine-resolution gamma camera

    International Nuclear Information System (INIS)

    Fujita, T.; Kataoka, J.; Nishiyama, T.; Ohsuka, S.; Nakamura, S.; Yamamoto, S.

    2014-01-01

    We are developing a technique to fabricate fine spatial resolution (FWHM<0.5mm) and cost-effective photon counting detectors, by using silicon photomultipliers (SiPMs) coupled with a finely pixelated scintillator plate. Unlike traditional X-ray imagers that use a micro-columnar CsI(Tl) plate, we can pixelate various scintillation crystal plates more than 1 mm thick, and easily develop large-area, fine-pitch scintillator arrays with high precision. Coupling a fine pitch scintillator array with a SiPM array results in a compact, fast-response detector that is ideal for X-ray, gamma-ray, and charged particle detection as used in autoradiography, gamma cameras, and photon counting CTs. As the first step, we fabricated a 2-D, cerium-doped Gd 3 Al 2 Ga 3 O 12 (Ce:GAGG) scintillator array of 0.25 mm pitch, by using a dicing saw to cut micro-grooves 50μm wide into a 1.0 mm thick Ce:GAGG plate. The scintillator plate is optically coupled with a 3.0×3.0mm pixel 4×4 SiPM array and read-out via the resistive charge-division network. Even when using this simple system as a gamma camera, we obtained excellent spatial resolution of 0.48 mm (FWHM) for 122 keV gamma-rays. We will present our plans to further improve the signal-to-noise ratio in the image, and also discuss a variety of possible applications in the near future

  11. Position-Sensitive Organic Scintillation Detectors for Nuclear Material Accountancy

    International Nuclear Information System (INIS)

    Hausladen, P.; Newby, J.; Blackston, M.

    2015-01-01

    Recent years have seen renewed interest in fast organic scintillators with pulse shape properties that enable neutron-gamma discrimination, in part because of the present shortage of He3, but primarily because of the diagnostic value of timing and pulse height information available from such scintillators. Effort at Oak Ridge National Laboratory (ORNL) associated with fast organic scintillators has concentrated on development of position-sensitive fast-neutron detectors for imaging applications. Two aspects of this effort are of interest. First, the development has revisited the fundamental limitations on pulseshape measurement imposed by photon counting statistics, properties of the scintillator, and properties of photomultiplier amplification. This idealized limit can then be used to evaluate the performance of the detector combined with data acquisition and analysis such as free-running digitizers with embedded algorithms. Second, the development of position sensitive detectors has enabled a new generation of fast-neutron imaging instruments and techniques with sufficient resolution to give new capabilities relevant to safeguards. Toward this end, ORNL has built and demonstrated a number of passive and active fast-neutron imagers, including a proof-of-concept passive imager capable of resolving individual fuel pins in an assembly via their neutron emanations. This presentation will describe the performance and construction of position-sensing fast-neutron detectors and present results of imaging measurements. (author)

  12. Low-noise low-jitter 32-pixels CMOS single-photon avalanche diodes array for single-photon counting from 300 nm to 900 nm

    Energy Technology Data Exchange (ETDEWEB)

    Scarcella, Carmelo; Tosi, Alberto, E-mail: alberto.tosi@polimi.it; Villa, Federica; Tisa, Simone; Zappa, Franco [Politecnico di Milano, Dipartimento di Elettronica, Informazione e Bioingegneria, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy)

    2013-12-15

    We developed a single-photon counting multichannel detection system, based on a monolithic linear array of 32 CMOS SPADs (Complementary Metal-Oxide-Semiconductor Single-Photon Avalanche Diodes). All channels achieve a timing resolution of 100 ps (full-width at half maximum) and a photon detection efficiency of 50% at 400 nm. Dark count rate is very low even at room temperature, being about 125 counts/s for 50 μm active area diameter SPADs. Detection performance and microelectronic compactness of this CMOS SPAD array make it the best candidate for ultra-compact time-resolved spectrometers with single-photon sensitivity from 300 nm to 900 nm.

  13. Liquid scintillation solutions

    International Nuclear Information System (INIS)

    Long, E.C.

    1976-01-01

    The liquid scintillation solution described includes a mixture of: a liquid scintillation solvent, a primary scintillation solute, a secondary scintillation solute, a variety of appreciably different surfactants, and a dissolving and transparency agent. The dissolving and transparency agent is tetrahydrofuran, a cyclic ether. The scintillation solvent is toluene. The primary scintillation solute is PPO, and the secondary scintillation solute is dimethyl POPOP. The variety of appreciably different surfactants is composed of isooctylphenol-polyethoxyethanol and sodium dihexyl sulphosuccinate [fr

  14. Dose optimization for dual-energy contrast-enhanced digital mammography based on an energy-resolved photon-counting detector: A Monte Carlo simulation study

    International Nuclear Information System (INIS)

    Lee, Youngjin; Lee, Seungwan; Kang, Sooncheol; Eom, Jisoo

    2017-01-01

    Dual-energy contrast-enhanced digital mammography (CEDM) has been used to decompose breast images and improve diagnostic accuracy for tumor detection. However, this technique causes an increase of radiation dose and an inaccuracy in material decomposition due to the limitations of conventional X-ray detectors. In this study, we simulated the dual-energy CEDM with an energy-resolved photon-counting detector (ERPCD) for reducing radiation dose and improving the quantitative accuracy of material decomposition images. The ERPCD-based dual-energy CEDM was compared to the conventional dual-energy CEDM in terms of radiation dose and quantitative accuracy. The correlation between radiation dose and image quality was also evaluated for optimizing the ERPCD-based dual-energy CEDM technique. The results showed that the material decomposition errors of the ERPCD-based dual-energy CEDM were 0.56–0.67 times lower than those of the conventional dual-energy CEDM. The imaging performance of the proposed technique was optimized at the radiation dose of 1.09 mGy, which is a half of the MGD for a single view mammogram. It can be concluded that the ERPCD-based dual-energy CEDM with an optimal exposure level is able to improve the quality of material decomposition images as well as reduce radiation dose. - Highlights: • Dual-energy mammography based on a photon-counting detector was simulated. • Radiation dose and image quality were evaluated for optimizing the proposed technique. • The proposed technique reduced radiation dose as well as improved image quality. • The proposed technique was optimized at the radiation dose of 1.09 mGy.

  15. A rod-like plastic scintillation detector for use in gamma-ray dosimetry and attempts to attain uniform response

    International Nuclear Information System (INIS)

    Yamashita, Mikio; Kawada, Yasushi; Avundukluoglu, M.A.

    1989-01-01

    The paper describes experiments made in an effort to develop scintillation dosimeters with emphasis on some attempts to attain a uniform response over the whole length of scintillators. A new method is proposed for measuring absorbed dose rate in plastic scintillators, using the photon-counting technique for measuring the total amount of luminescence from the scintillator exposed to gamma-rays. If a rod plastic scintillator and lucite light guides with well-polished and non-coated surfaces are surrounded by non-reflective material with a definite air gap between them, the scintillation light is transmitted to the PMTs only by the inner total reflection from the surface; a good uniformity of response could be expected if it were not for light attenuation in the transmission through the medium. With a diffusion reflector in non-optical contact with the scintillator surface, the scintillation light which otherwise would escape from the surface is partly reflected back into the scintillator. This effect is examined quantitatively. Measurements show that the presence of the diffusion reflector permits the uniformity of response to be improved considerably; a uniformity within 20 % is obtained. (N.K.)

  16. Radiation damage in plastic scintillators

    International Nuclear Information System (INIS)

    Majewski, S.

    1990-01-01

    Results of radiation damage studies in plastic scintillators are reviewed and critically analyzed from the point of view of applications of plastic scintillators in calorimetric detectors for the SSC. Damage to transmission and to fluorescent yield in different conditions is discussed. New directions in R ampersand D are outlined. Several examples are given of the most recent data on the new scintillating materials made with old and new plastics and fluors, which are exhibiting significantly improved radiation resistance. With a present rate of a vigorous R D programme, the survival limits in the vicinity of 100 MRad seem to be feasible within a couple of years

  17. Scintillating camera

    International Nuclear Information System (INIS)

    Vlasbloem, H.

    1976-01-01

    The invention relates to a scintillating camera and in particular to an apparatus for determining the position coordinates of a light pulse emitting point on the anode of an image intensifier tube which forms part of a scintillating camera, comprising at least three photomultipliers which are positioned to receive light emitted by the anode screen on their photocathodes, circuit means for processing the output voltages of the photomultipliers to derive voltages that are representative of the position coordinates; a pulse-height discriminator circuit adapted to be fed with the sum voltage of the output voltages of the photomultipliers for gating the output of the processing circuit when the amplitude of the sum voltage of the output voltages of the photomultipliers lies in a predetermined amplitude range, and means for compensating the distortion introduced in the image on the anode screen

  18. Scintillating fibres

    International Nuclear Information System (INIS)

    Nahnhauer, R.

    1990-01-01

    In the search for new detector techniques, scintillating fibre technology has already gained a firm foothold, and is a strong contender for the extreme experimental conditions of tomorrow's machines. Organized by a group from the Institute of High Energy Physics, Berlin-Zeuthen, a workshop held from 3-5 September in the nearby village of Blossin brought together experts from East and West, and from science and industry

  19. Scintillating fibres

    Energy Technology Data Exchange (ETDEWEB)

    Nahnhauer, R. [IHEP Zeuthen (Germany)

    1990-11-15

    In the search for new detector techniques, scintillating fibre technology has already gained a firm foothold, and is a strong contender for the extreme experimental conditions of tomorrow's machines. Organized by a group from the Institute of High Energy Physics, Berlin-Zeuthen, a workshop held from 3-5 September in the nearby village of Blossin brought together experts from East and West, and from science and industry.

  20. The quest for the ideal inorganic scintillator

    International Nuclear Information System (INIS)

    Derenzo, S.E.; Weber, M.J.; Bourret-Courchesne, E.; Klintenberg, M.K.

    2002-01-01

    The past half century has witnessed the discovery of many new inorganic scintillator materials and numerous advances in our understanding of the basic physical processes governing the transformation of ionizing radiation into scintillation light. Whereas scintillators are available with a good combination of physical properties, none provides the desired combination of stopping power, light output, and decay time. A review of the numerous scintillation mechanisms of known inorganic scintillators reveals why none of them is both bright and fast. The mechanisms of radiative recombination in wide-bandgap direct semiconductors, however, remain relatively unexploited for scintillators. We describe how suitably doped semiconductor scintillators could provide a combination of high light output, short decay time, and linearity of response that approach fundamental limits

  1. Uranium-scintillator device

    International Nuclear Information System (INIS)

    Smith, S.D.

    1979-01-01

    The calorimeter subgroup of the 1977 ISABELLE Summer Workshop strongly recommended investigation of the uranium-scintillator device because of its several attractive features: (1) increased resolution for hadronic energy, (2) fast time response, (3) high density (i.e., 16 cm of calorimeter per interaction length), and, in comparison with uranium--liquid argon detectors, (4) ease of construction, (5) simple electronics, and (6) lower cost. The AFM group at the CERN ISR became interested in such a calorimeter for substantially the same reasons, and in the fall of 1977 carried out tests on a uranium-scintillator (U-Sc) calorimeter with the same uranium plates used in their 1974 studies of the uranium--liquid argon (U-LA) calorimeter. The chief disadvantage of the scintillator test was that the uranium plates were too small to fully contain the hadronic showers. However, since the scintillator and liquid argon tests were made with the plates, direct comparison of the two types of devices could be made

  2. FoCuS-point: software for STED fluorescence correlation and time-gated single photon counting

    DEFF Research Database (Denmark)

    Waithe, Dominic; Clausen, Mathias P; Sezgin, Erdinc

    2016-01-01

    to be established quickly and efficiently. AVAILABILITY AND IMPLEMENTATION: FoCuS-point is written in python and is available through the github repository: https://github.com/dwaithe/FCS_point_correlator. Furthermore, compiled versions of the code are available as executables which can be run directly in Linux...

  3. Development of superconducting tunnel junction as photon counting detector in astronomy; Developpement de jonctions supraconductrices a effet tunnel pour le comptage de photons en astronomie

    Energy Technology Data Exchange (ETDEWEB)

    Jorel, C

    2004-12-15

    This work describes the development of S/Al-AlOx-Al/S Superconducting Tunnel Junctions (STJ) to count photons for astronomical applications in the near-infrared. The incoming light energy is converted into excited charges in a superconducting layer (S, either Nb or Ta) with a population proportional to the deposited energy. The photon energy can thus be evaluated by integrating the tunnel current induced in a voltage biased junction at a very low temperature (100 mK). The performance of STJ for light detection is discussed in the first chapter and compared with the best performances obtained with other techniques based on either superconductors. At the beginning of the thesis, a previous manufacturing process made it possible to obtain good quality Nb based junctions and preliminary results for photon counting. The objective of the thesis was to replace Nb as absorber with Ta, an intrinsically more sensitive material, and secondly to develop a new and more efficient manufacturing process. We first focused on the optimization of the Tantalum thin film quality. Structural analysis showed that these films can be grown epitaxially by magnetron sputtering onto an R-plane sapphire substrate heated to 600 Celsius degrees and covered by a thin Nb buffer layer. Electrical transport measurement from room to low temperatures gave excellent Relative Resistive Ratios of about 50 corresponding to mean free path of the order of 100 nm. Then, we conceived an original manufacturing process batch on 3 inch diameter sapphire substrate with five mask levels. These masks made it possible to produce single pixel STJ of different sizes (from 25*25 to 50*50 square microns) and shapes. We also produced multiple junctions onto a common absorber as well as 9-pixel arrays. Thanks to the development of this process we obtained a very large percentage of quality junctions (>90%) with excellent measured normal resistances of a few micro-ohm cm{sup 2} and low leakage currents of the order of one

  4. SU-C-206-01: Impact of Charge Sharing Effect On Sub-Pitch Resolution for CZT-Based Photon Counting CT Systems

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, X; Cheng, Z; Deen, J; Peng, H [McMaster University, Hamilton, Ontario (Canada); Xing, L [Stanford University School of Medicine, Stanford, CA (United States)

    2016-06-15

    Purposes: Photon counting CT is a new imaging technology that can provide tissue composition information such as calcium/iodine content quantification. Cadmium zinc telluride CZT is considered a good candidate the photon counting CT due to its relatively high atomic number and band gap. One potential challenge is the degradation of both spatial and energy resolution as the fine electrode pitch is deployed (<50 µm). We investigated the extent of charge sharing effect as functions of gap width, bias voltage and depth-of-interaction (DOI). Methods: The initial electron cloud size and diffusion process were modeled analytically. The valid range of charge sharing effect refers to the range over which both signals of adjacent electrodes are above the triggering threshold (10% of the amplitude of 60keV X-ray photons). The intensity ratios of output in three regions (I1/I2/I3: left pixel, gap area and right pixel) were calculated. With Gaussian white noises modeled (a SNR of 5 based upon the preliminary experiments), the sub-pitch resolution as a function of the spatial position in-between two pixels was studied. Results: The valid range of charge sharing increases linearly with depth-of-interaction (DOI) but decreases with gap width and bias voltage. For a 1.5mm thickness CZT detector (pitch: 50µm, bias: 400 V), the range increase from ∼90µm up to ∼110µm. Such an increase can be attributed to a longer travel distance and the associated electron cloud broadening. The achievable sub-pitch resolution is in the range of ∼10–30µm. Conclusion: The preliminary results demonstrate that sub-pixel spatial resolution can be achieved using the ratio of amplitudes of two neighboring pixels. Such ratio may also be used to correct charge loss and help improve energy resolution of a CZT detector. The impact of characteristic X-rays hitting adjacent pixels (i.e., multiple interaction) on charge sharing is currently being investigated.

  5. Dose optimization for dual-energy contrast-enhanced digital mammography based on an energy-resolved photon-counting detector: A Monte Carlo simulation study

    Science.gov (United States)

    Lee, Youngjin; Lee, Seungwan; Kang, Sooncheol; Eom, Jisoo

    2017-03-01

    Dual-energy contrast-enhanced digital mammography (CEDM) has been used to decompose breast images and improve diagnostic accuracy for tumor detection. However, this technique causes an increase of radiation dose and an inaccuracy in material decomposition due to the limitations of conventional X-ray detectors. In this study, we simulated the dual-energy CEDM with an energy-resolved photon-counting detector (ERPCD) for reducing radiation dose and improving the quantitative accuracy of material decomposition images. The ERPCD-based dual-energy CEDM was compared to the conventional dual-energy CEDM in terms of radiation dose and quantitative accuracy. The correlation between radiation dose and image quality was also evaluated for optimizing the ERPCD-based dual-energy CEDM technique. The results showed that the material decomposition errors of the ERPCD-based dual-energy CEDM were 0.56-0.67 times lower than those of the conventional dual-energy CEDM. The imaging performance of the proposed technique was optimized at the radiation dose of 1.09 mGy, which is a half of the MGD for a single view mammogram. It can be concluded that the ERPCD-based dual-energy CEDM with an optimal exposure level is able to improve the quality of material decomposition images as well as reduce radiation dose.

  6. Characterisation of Al{sub 0.52}In{sub 0.48}P mesa p-i-n photodiodes for X-ray photon counting spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Butera, S., E-mail: S.Butera@sussex.ac.uk; Lioliou, G.; Barnett, A. M. [Semiconductor Materials and Device Laboratory, School of Engineering and Informatics, University of Sussex, Brighton BN1 9QT (United Kingdom); Krysa, A. B. [EPSRC National Centre for III-V Technologies, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2016-07-14

    Results characterising the performance of thin (2 μm i-layer) Al{sub 0.52}In{sub 0.48}P p{sup +}-i-n{sup +} mesa photodiodes for X-ray photon counting spectroscopy are reported at room temperature. Two 200 μm diameter and two 400 μm diameter Al{sub 0.52}In{sub 0.48}P p{sup +}-i-n{sup +} mesa photodiodes were studied. Dark current results as a function of applied reverse bias are shown; dark current densities <3 nA/cm{sup 2} were observed at 30 V (150 kV/cm) for all the devices analysed. Capacitance measurements as a function of applied reverse bias are also reported. X-ray spectra were collected using 10 μs shaping time, with the device illuminated by an {sup 55}Fe radioisotope X-ray source. Experimental results showed that the best energy resolution (FWHM) achieved at 5.9 keV was 930 eV for the 200 μm Al{sub 0.52}In{sub 0.48}P diameter devices, when reverse biased at 15 V. System noise analysis was also carried out, and the different noise contributions were computed.

  7. Characterization of a mammographic system based on single photon counting pixel arrays coupled to GaAs x-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Amendolia, S. R.; Bisogni, M. G.; Delogu, P.; Fantacci, M. E.; Paternoster, G.; Rosso, V.; Stefanini, A. [Str. Dip. di Matematica e Fisica dell' Universita di Sassari, Via Vienna 2, I-07100, Sassari (Italy) and Istituto Nazionale di Fisica Nucleare INFN Sezione di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa (Italy); Dip. di Fisica ' ' E. Fermi' ' , Universita di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa (Italy) and Istituto Nazionale di Fisica Nucleare INFN Sezione di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa (Italy); Dip. di Fisica ' ' E. Fermi' ' , Universita di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa (Italy); Dip. di Fisica ' ' E. Fermi' ' , Universita di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa (Italy) and Istituto Nazionale di Fisica Nucleare INFN Sezione di Pisa, Largo B. Pontecorvo 3, I-56127, Pisa (Italy)

    2009-04-15

    The authors report on the imaging capabilities of a mammographic system demonstrator based on GaAs pixel detectors operating in single photon counting (SPC) mode. The system imaging performances have been assessed by means of the transfer functions: The modulation transfer function (MTF), the normalized noise power spectrum, and the detective quantum efficiency (DQE) have been measured following the guidelines of the IEC 62220-1-2 protocol. The transfer function analysis has shown the high spatial resolution capabilities of the GaAs detectors. The MTF calculated at the Nyquist frequency (2.94 cycles/mm) is indeed 60%. The DQE, measured with a standard mammographic beam setup (Mo/Mo, 28 kVp, with 4 mm Al added filter) and calculated at zero frequency, is 46%. Aiming to further improve the system's image quality, the authors investigate the DQE limiting factors and show that they are mainly related to system engineering. For example, the authors show that optimization of the image equalization procedure increases the DQE(0) up to 74%, which is better than the DQE(0) of most clinical mammographic systems. The authors show how the high detection efficiency of GaAs detectors and the noise discrimination associated with the SPC technology allow optimizing the image quality in mammography. In conclusion, the authors propose technological solutions to exploit to the utmost the potentiality of GaAs detectors coupled to SPC electronics.

  8. Limits on Achievable Dimensional and Photon Efficiencies with Intensity-Modulation and Photon-Counting Due to Non-Ideal Photon-Counter Behavior

    Science.gov (United States)

    Moision, Bruce; Erkmen, Baris I.; Farr, William; Dolinar, Samuel J.; Birnbaum, Kevin M.

    2012-01-01

    An ideal intensity-modulated photon-counting channel can achieve unbounded photon information efficiencies (PIEs). However, a number of limitations of a physical system limit the practically achievable PIE. In this paper, we discuss several of these limitations and illustrate their impact on the channel. We show that, for the Poisson channel, noise does not strictly bound PIE, although there is an effective limit, as the dimensional information efficiency goes as e[overline] e PIE beyond a threshold PIE. Since the Holevo limit is bounded in the presence of noise, this illustrates that the Poisson approximation is invalid at large PIE for any number of noise modes. We show that a finite transmitter extinction ratio bounds the achievable PIE to a maximum that is logarithmic in the extinction ratio. We show how detector jitter limits the ability to mitigate noise in the PPM signaling framework. We illustrate a method to model detector blocking when the number of detectors is large, and illustrate mitigation of blocking with spatial spreading and altering. Finally, we illustrate the design of a high photon efficiency system using state-of-the-art photo-detectors and taking all these effects into account.

  9. Material decomposition through weighted imaged subtraction in dual-energy spectral mammography with an energy-resolved photon-counting detector using Monte Carlo Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Eom, Ji Soo; Kang, Soon Cheol; Lee, Seung Wan [Konyang University, Daejeon (Korea, Republic of)

    2017-09-15

    Mammography is commonly used for screening early breast cancer. However, mammographic images, which depend on the physical properties of breast components, are limited to provide information about whether a lesion is malignant or benign. Although a dual-energy subtraction technique decomposes a certain material from a mixture, it increases radiation dose and degrades the accuracy of material decomposition. In this study, we simulated a breast phantom using attenuation characteristics, and we proposed a technique to enable the accurate material decomposition by applying weighting factors for the dual-energy mammography based on a photon-counting detector using a Monte Carlo simulation tool. We also evaluated the contrast and noise of simulated breast images for validating the proposed technique. As a result, the contrast for a malignant tumor in the dual-energy weighted subtraction technique was 0.98 and 1.06 times similar than those in the general mammography and dual-energy subtraction techniques, respectively. However the contrast between malignant and benign tumors dramatically increased 13.54 times due to the low contrast of a benign tumor. Therefore, the proposed technique can increase the material decomposition accuracy for malignant tumor and improve the diagnostic accuracy of mammography.

  10. Simultaneous resolution of spectral and temporal properties of UV and visible fluorescence using single-photon counting with a position-sensitive detector

    International Nuclear Information System (INIS)

    Kelly, L.A.; Trunk, J.G.; Polewski, K.; Sutherland, J.C.

    1995-01-01

    A new fluorescence spectrometer has been assembled at the U9B beamline of the National Synchrotron Light Source to allow simultaneous multiwavelength and time-resolved fluorescence detection, as well as spatial imaging of the sample fluorescence. The spectrometer employs monochromatized, tunable UV and visible excitation light from a synchrotron bending magnet and an imaging spectrograph equipped with a single-photon sensitive emission detector. The detector is comprised of microchannel plates in series, with a resistive anode for encoding the position of the photon-derived current. The centroid position of the photon-induced electron cascade is derived in a position analyzer from the four signals measured at the corners of the resistive anode. Spectral information is obtained by dispersing the fluorescence spectrum across one dimension of the detector photocathode. Timing information is obtained by monitoring the voltage divider circuit at the last MCP detector. The signal from the MCP is used as a ''start'' signal to perform a time-correlated single photon counting experiment. The analog signal representing the position, and hence wavelength, is digitized concomitantly with the start/stop time difference and stored in the two-dimensional histogramming memory of a multiparameter analyzer

  11. Characterization of the Photon Counting CHASE Jr., Chip Built in a 40-nm CMOS Process With a Charge Sharing Correction Algorithm Using a Collimated X-Ray Beam

    Energy Technology Data Exchange (ETDEWEB)

    Krzyżanowska, A. [AGH-UST, Cracow; Deptuch, G. W. [Fermilab; Maj, P. [AGH-UST, Cracow; Gryboś, P. [AGH-UST, Cracow; Szczygieł, R. [AGH-UST, Cracow

    2017-08-01

    This paper presents the detailed characterization of a single photon counting chip, named CHASE Jr., built in a CMOS 40-nm process, operating with synchrotron radiation. The chip utilizes an on-chip implementation of the C8P1 algorithm. The algorithm eliminates the charge sharing related uncertainties, namely, the dependence of the number of registered photons on the discriminator’s threshold, set for monochromatic irradiation, and errors in the assignment of an event to a certain pixel. The article presents a short description of the algorithm as well as the architecture of the CHASE Jr., chip. The analog and digital functionalities, allowing for proper operation of the C8P1 algorithm are described, namely, an offset correction for two discriminators independently, two-stage gain correction, and different operation modes of the digital blocks. The results of tests of the C8P1 operation are presented for the chip bump bonded to a silicon sensor and exposed to the 3.5- μm -wide pencil beam of 8-keV photons of synchrotron radiation. It was studied how sensitive the algorithm performance is to the chip settings, as well as the uniformity of parameters of the analog front-end blocks. Presented results prove that the C8P1 algorithm enables counting all photons hitting the detector in between readout channels and retrieving the actual photon energy.

  12. Measurements of Ultra-Fast single photon counting chip with energy window and 75 μm pixel pitch with Si and CdTe detectors

    International Nuclear Information System (INIS)

    Maj, P.; Grybos, P.; Kasinski, K.; Koziol, A.; Krzyzanowska, A.; Kmon, P.; Szczygiel, R.; Zoladz, M.

    2017-01-01

    Single photon counting pixel detectors become increasingly popular in various 2-D X-ray imaging techniques and scientific experiments mainly in solid state physics, material science and medicine. This paper presents architecture and measurement results of the UFXC32k chip designed in a CMOS 130 nm process. The chip consists of about 50 million transistors and has an area of 9.64 mm × 20.15 mm. The core of the IC is a matrix of 128 × 256 pixels of 75 μm pitch. Each pixel contains a CSA, a shaper with tunable gain, two discriminators with correction circuits and two 14-bit ripple counters operating in a normal mode (with energy window), a long counter mode (one 28-bit counter) and a zero-dead time mode. Gain and noise performance were verified with X-ray radiation and with the chip connected to Si (320 μm thick) and CdTe (750 μ m thick) sensors.

  13. Fabrication and characterization of a 32 x 32 array digital Si-PIN X-ray detector for a single photon counting image sensor

    International Nuclear Information System (INIS)

    Seo, Jungho; Kim, Jinyoung; Lim, Hyunwoo; Park, Jingoo; Lee, Songjun; Kim, Bonghoe; Jeon, Sungchae; Huh, Young

    2010-01-01

    A Si-PIN X-ray detector for digital x-ray imaging with single photon counting capability has been fabricated and characterized. It consists of an array of 32 x 32 pixels with an area of 80 x 80 μm 2 . An extrinsic gettering process was performed to reduce the leakage current by removing the impurities and defects from the X-ray detector's Si substrate. Multiple guard-rings (MGRs) and metal filed plates (MFPs) techniques were adopted to reduce the leakage current and to improve the breakdown performance. The simulation verified that the breakdown voltage was improved with the MGRs and that the leakage current was significantly reduced with the MFPs. The electrical properties, such as the leakage current and the breakdown voltage, of the Si-PIN X-ray detector were characterized. The extrinsic gettering process played a significant role in reducing the leakage current, and a leakage current lower than 60 pA could be achieved at 100 V dc .

  14. Greenberger-Horne-Zeilinger-type and W-type entangled coherent states: Generation and Bell-type inequality tests without photon counting

    International Nuclear Information System (INIS)

    Jeong, Hyunseok; Nguyen Ba An

    2006-01-01

    We study Greenberger-Horne-Zeilinger-type (GHZ-type) and W-type three-mode entangled coherent states. Both types of entangled coherent states violate Mermin's version of the Bell inequality with threshold photon detection (i.e., without photon counting). Such an experiment can be performed using linear optics elements and threshold detectors with significant Bell violations for GHZ-type entangled coherent states. However, to demonstrate Bell-type inequality violations for W-type entangled coherent states, additional nonlinear interactions are needed. We also propose an optical scheme to generate W-type entangled coherent states in free-traveling optical fields. The required resources for the generation are a single-photon source, a coherent state source, beam splitters, phase shifters, photodetectors, and Kerr nonlinearities. Our scheme does not necessarily require strong Kerr nonlinear interactions; i.e., weak nonlinearities can be used for the generation of the W-type entangled coherent states. Furthermore, it is also robust against inefficiencies of the single-photon source and the photon detectors

  15. Influence of pulse-height discrimination threshold for photon counting on the accuracy of singlet oxygen luminescence measurement

    International Nuclear Information System (INIS)

    Lin, Huiyun; Chen, Defu; Wang, Min; Lin, Juqiang; Li, Buhong; Xie, Shusen

    2011-01-01

    Direct measurement of near-infrared (NIR) luminescence around 1270 nm is the golden standard of singlet oxygen ( 1 O 2 ) identification. In this study, the influence of pulse-height discrimination threshold on measurement accuracy of the 1 O 2 luminescence that is generated from the photoirradiation of meso-tetra (N-methyl-4-pyridyl) morphine tetra-tosylate (TMPyP) in aqueous solution was investigated by using our custom-developed detection system. Our results indicate that the discrimination threshold has a significant influence on the absolute 1 O 2 luminescence counts, and the optimal threshold for our detection system is found to be about − 41.2 mV for signal discrimination. After optimization, the derived triplet-state and 1 O 2 lifetimes of TMPyP in aqueous solution are found to be 1.73 ± 0.03 and 3.70 ± 0.04 µs, respectively, and the accuracy of measurement was further independently demonstrated using the laser flash photolysis technique

  16. Liquid scintillation solution

    International Nuclear Information System (INIS)

    Long, E.C.

    1977-01-01

    A liquid scintillation solution is described which includes (1) a scintillation solvent (toluene and xylene), (2) a primary scintillation solute (PPO and Butyl PBD), (3) a secondary scintillation solute (POPOP and Dimethyl POPOP), (4) a plurality of substantially different surfactants and (5) a filter dissolving and/or transparentizing agent. 8 claims

  17. Scintillator structure

    International Nuclear Information System (INIS)

    Cusano, D.A.; Swank, R.K.; White, P.J.

    1978-01-01

    Scintillator structures are described in which the phosphor is embedded or suspended in an optically transparent matrix which is selected or adjusted to have an index of refraction which is approximately equal to that of the phosphor at the wavelength of the light emitted by the phosphor. The matrix may be glass, copoly 2-vinyl naphthalene/vinyl toluene or a liquid e.g. Br-naphthalene and optionally CH 3 I, the ratio of components being adjusted to give the desired refractive index. The polymer may be made in situ or a mixture of phosphor and polymer formed e.g. by freeze drying a solution and pulverizing, and then heating. Specified dyes may be used for converting the emitted light to other wavelengths. (author)

  18. Modular scintillation camera

    International Nuclear Information System (INIS)

    Barrett, H. H.

    1985-01-01

    Improved optical coupling modules to be used in coded-aperture-type radiographic imaging systems. In a first system, a rotating slit coded-aperture is employed between the radioactive object and the module. The module consists of one pair of side-by-side photomultipliers receiving light rays from a scintillation crystal exposed to the object via the coded-aperture. The light rays are guided to the photomultipliers by a mask having a central transverse transparent window, or by a cylindrical lens, the mask or lens being mounted in a light-conveying quartz block assembly providing internal reflections at opposite faces of the assembly. This generates output signals from the photomultipliers which can be utilized to compute one-dimensional coordinate values for restoring the image of the radioactive object on a display screen. In another form of optical coupling module, usable with other types of coded-apertures, four square photomultipliers form a substantially square block and receive light rays from scintillations from a scintillation crystal exposed to the radioactive object via the coded-aperture. The light rays are guided to the photomultipliers by a square mask or a centrally transparent square lens configuration mounted in a light-conveying assembly formed by internally reflecting quartz blocks, the optical rays being directed to the respective photomultipliers so as to generate resultant output signals which can be utilized to compute image coordinate values for two-dimensional representation of the radioactive object being examined

  19. Direct activity determination of Mn-54 and Zn-65 by a non-extrapolation liquid scintillation method

    CSIR Research Space (South Africa)

    Simpson, BRS

    2004-02-01

    Full Text Available . The simple decay scheme exhibited by these radionuclides, with the emission of an energetic gamma ray, allows the absolute activity to be determined from 4pie-gamma data by direct calculation without the need for efficiency extrapolation. The method, which...

  20. Directionally solidified Eu doped CaF.sub.2./sub./Li.sub.3./sub.AlF.sub.6./sub. eutectic scintillator for neutron detection

    Czech Academy of Sciences Publication Activity Database

    Kamada, K.; Hishinuma, K.; Kurosawa, S.; Shoji, Y.; Pejchal, Jan; Ohashi, Y.; Yokota, Y.; Yoshikawa, A.

    2015-01-01

    Roč. 50, Dec (2015), 71-75 ISSN 0925-3467 Institutional support: RVO:68378271 Keywords : scintillator * eutectic * micro-pulling down Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2015

  1. Optimization of a dual-energy contrast-enhanced technique for a photon-counting digital breast tomosynthesis system: I. A theoretical model

    International Nuclear Information System (INIS)

    Carton, Ann-Katherine; Ullberg, Christer; Lindman, Karin; Acciavatti, Raymond; Francke, Tom; Maidment, Andrew D. A.

    2010-01-01

    Purpose: Dual-energy (DE) iodine contrast-enhanced x-ray imaging of the breast has been shown to identify cancers that would otherwise be mammographically occult. In this article, theoretical modeling was performed to obtain optimally enhanced iodine images for a photon-counting digital breast tomosynthesis (DBT) system using a DE acquisition technique. Methods: In the system examined, the breast is scanned with a multislit prepatient collimator aligned with a multidetector camera. Each detector collects a projection image at a unique angle during the scan. Low-energy (LE) and high-energy (HE) projection images are acquired simultaneously in a single scan by covering alternate collimator slits with Sn and Cu filters, respectively. Sn filters ranging from 0.08 to 0.22 mm thickness and Cu filters from 0.11 to 0.27 mm thickness were investigated. A tube voltage of 49 kV was selected. Tomographic images, hereafter referred to as DBT images, were reconstructed using a shift-and-add algorithm. Iodine-enhanced DBT images were acquired by performing a weighted logarithmic subtraction of the HE and LE DBT images. The DE technique was evaluated for 20-80 mm thick breasts. Weighting factors, w t , that optimally cancel breast tissue were computed. Signal-difference-to-noise ratios (SDNRs) between iodine-enhanced and nonenhanced breast tissue normalized to the square root of the mean glandular dose (MGD) were computed as a function of the fraction of the MGD allocated to the HE images. Peak SDNR/√(MGD) and optimal dose allocations were identified. SDNR/√(MGD) and dose allocations were computed for several practical feasible system configurations (i.e., determined by the number of collimator slits covered by Sn and Cu). A practical system configuration and Sn-Cu filter pair that accounts for the trade-off between SDNR, tube-output, and MGD were selected. Results: w t depends on the Sn-Cu filter combination used, as well as on the breast thickness; to optimally cancel 0

  2. Femtosecond Photon-Counting Receiver

    Science.gov (United States)

    Krainak, Michael A.; Rambo, Timothy M.; Yang, Guangning; Lu, Wei; Numata, Kenji

    2016-01-01

    An optical correlation receiver is described that provides ultra-precise distance and/or time/pulse-width measurements even for weak (single photons) and short (femtosecond) optical signals. A new type of optical correlation receiver uses a fourth-order (intensity) interferometer to provide micron distance measurements even for weak (single photons) and short (femtosecond) optical signals. The optical correlator uses a low-noise-integrating detector that can resolve photon number. The correlation (range as a function of path delay) is calculated from the variance of the photon number of the difference of the optical signals on the two detectors. Our preliminary proof-of principle data (using a short-pulse diode laser transmitter) demonstrates tens of microns precision.

  3. Industrial X-ray imaging based on scintillators and CMOS APS array: direct X-ray irradiation effects

    International Nuclear Information System (INIS)

    Kim, Kwang Hyun; Jeon, Sung Chae; Kim, Young Soo; Cho, Gyuseong

    2005-01-01

    To see the effects of the direct X-ray in a Lanex screen-coupled CMOS APS imager, we measured modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). These measurements were performed under the condition of non-destructive test (NDT). By increasing the cumulative exposure on the imager, the MTF was degraded, and also leading to the DQE degradation. Each parameter changed by the exposure is described in detail

  4. MO-FG-CAMPUS-IeP1-02: Dose Reduction in Contrast-Enhanced Digital Mammography Using a Photon-Counting Detector

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S; Kang, S; Eom, J [Konyang University, Daejeon (Korea, Republic of)

    2016-06-15

    Purpose: Photon-counting detectors (PCDs) allow multi-energy X-ray imaging without additional exposures and spectral overlap. This capability results in the improvement of accuracy of material decomposition for dual-energy X-ray imaging and the reduction of radiation dose. In this study, the PCD-based contrast-enhanced dual-energy mammography (CEDM) was compared with the conventional CDEM in terms of radiation dose, image quality and accuracy of material decomposition. Methods: A dual-energy model was designed by using Beer-Lambert’s law and rational inverse fitting function for decomposing materials from a polychromatic X-ray source. A cadmium zinc telluride (CZT)-based PCD, which has five energy thresholds, and iodine solutions included in a 3D half-cylindrical phantom, which composed of 50% glandular and 50% adipose tissues, were simulated by using a Monte Carlo simulation tool. The low- and high-energy images were obtained in accordance with the clinical exposure conditions for the conventional CDEM. Energy bins of 20–33 and 34–50 keV were defined from X-ray energy spectra simulated at 50 kVp with different dose levels for implementing the PCD-based CDEM. The dual-energy mammographic techniques were compared by means of absorbed dose, noise property and normalized root-mean-square error (NRMSE). Results: Comparing to the conventional CEDM, the iodine solutions were clearly decomposed for the PCD-based CEDM. Although the radiation dose for the PCD-based CDEM was lower than that for the conventional CEDM, the PCD-based CDEM improved the noise property and accuracy of decomposition images. Conclusion: This study demonstrates that the PCD-based CDEM allows the quantitative material decomposition, and reduces radiation dose in comparison with the conventional CDEM. Therefore, the PCD-based CDEM is able to provide useful information for detecting breast tumor and enhancing diagnostic accuracy in mammography.

  5. WE-DE-207B-04: Quantitative Contrast-Enhanced Spectral Mammography Based On Photon-Counting Detectors: A Feasibility Study

    Energy Technology Data Exchange (ETDEWEB)

    Ding, H; Zhou, B; Beidokhti, D; Molloi, S [University of California, Irvine, CA (United States)

    2016-06-15

    Purpose: To investigate the feasibility of accurate quantification of iodine mass thickness in contrast-enhanced spectral mammography. Methods: Experimental phantom studies were performed on a spectral mammography system based on Si strip photon-counting detectors. Dual-energy images were acquired using 40 kVp and a splitting energy of 34 keV with 3 mm Al pre-filtration. The initial calibration was done with glandular and adipose tissue equivalent phantoms of uniform thicknesses and iodine disk phantoms of various concentrations. A secondary calibration was carried out using the iodine signal obtained from the dual-energy decomposed images and the known background phantom thicknesses and densities. The iodine signal quantification method was validated using phantoms composed of a mixture of glandular and adipose materials, for various breast thicknesses and densities. Finally, the traditional dual-energy weighted subtraction method was also studied as a comparison. The measured iodine signal from both methods was compared to the known iodine concentrations of the disk phantoms to characterize the quantification accuracy. Results: There was good agreement between the iodine mass thicknesses measured using the proposed method and the known values. The root-mean-square (RMS) error was estimated to be 0.2 mg/cm2. The traditional weighted subtraction method also predicted a linear correlation between the measured signal and the known iodine mass thickness. However, the correlation slope and offset values were strongly dependent on the total breast thickness and density. Conclusion: The results of the current study suggest that iodine mass thickness can be accurately quantified with contrast-enhanced spectral mammography. The quantitative information can potentially improve the differentiation between benign and malignant legions. Grant funding from Philips Medical Systems.

  6. WE-DE-207B-04: Quantitative Contrast-Enhanced Spectral Mammography Based On Photon-Counting Detectors: A Feasibility Study

    International Nuclear Information System (INIS)

    Ding, H; Zhou, B; Beidokhti, D; Molloi, S

    2016-01-01

    Purpose: To investigate the feasibility of accurate quantification of iodine mass thickness in contrast-enhanced spectral mammography. Methods: Experimental phantom studies were performed on a spectral mammography system based on Si strip photon-counting detectors. Dual-energy images were acquired using 40 kVp and a splitting energy of 34 keV with 3 mm Al pre-filtration. The initial calibration was done with glandular and adipose tissue equivalent phantoms of uniform thicknesses and iodine disk phantoms of various concentrations. A secondary calibration was carried out using the iodine signal obtained from the dual-energy decomposed images and the known background phantom thicknesses and densities. The iodine signal quantification method was validated using phantoms composed of a mixture of glandular and adipose materials, for various breast thicknesses and densities. Finally, the traditional dual-energy weighted subtraction method was also studied as a comparison. The measured iodine signal from both methods was compared to the known iodine concentrations of the disk phantoms to characterize the quantification accuracy. Results: There was good agreement between the iodine mass thicknesses measured using the proposed method and the known values. The root-mean-square (RMS) error was estimated to be 0.2 mg/cm2. The traditional weighted subtraction method also predicted a linear correlation between the measured signal and the known iodine mass thickness. However, the correlation slope and offset values were strongly dependent on the total breast thickness and density. Conclusion: The results of the current study suggest that iodine mass thickness can be accurately quantified with contrast-enhanced spectral mammography. The quantitative information can potentially improve the differentiation between benign and malignant legions. Grant funding from Philips Medical Systems.

  7. A feasibility study of projection-based energy weighting based on a photon-counting detector in contrast-enhanced digital subtraction mammography: a simulation study

    International Nuclear Information System (INIS)

    Choi, Sunghoon; Lee, Seungwan; Choi, Yuna; Kim, Heejoung

    2014-01-01

    Contrast media, such as iodine and gadolinium, are generally used in digital subtraction mammography to enhance the contrast between target and background materials. In digital subtraction mammography, where one image (with contrast medium) is subtracted from another (anatomical background) to facilitate visualization of the tumor structure, tumors can be more easily distinguished after the injection of a contrast medium. In order to have more an effective method to increase the contrast-to-noise ratio (CNR), we applied a projection-based energy-weighting method. The purpose of this study is to demonstrate the feasibility of using the projection-based energy-weighting method in digital subtraction mammography. Unlike some other previous studies, we applied the projection-based energy-weighting method to more practical mammography conditions by using the Monte Carlo method to simulate four different iodine solutions embedded in a breast phantom comprised of 50% adipose and 50% glandular tissues. We also considered an optimal tube voltage and anode/filter combination in digital iodine contrast media mammography in order to maximize the figure-of-merit (FOM). The simulated source energy was from 20 to 45 keV to prevent electronic noise and include the k-edge energy of iodine (33.2 keV). The results showed that the projection-based energy-weighting improved the CNR by factors of 1.05 - 1.86 compared to the conventionally integrated images. Consequently, the CNR of digital subtraction mammography images can be improved by using projection-based energy-weighting with photon-counting detectors.

  8. A feasibility study of projection-based energy weighting based on a photon-counting detector in contrast-enhanced digital subtraction mammography: a simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Sunghoon; Lee, Seungwan; Choi, Yuna; Kim, Heejoung [Yonsei University, Wonju (Korea, Republic of)

    2014-06-15

    Contrast media, such as iodine and gadolinium, are generally used in digital subtraction mammography to enhance the contrast between target and background materials. In digital subtraction mammography, where one image (with contrast medium) is subtracted from another (anatomical background) to facilitate visualization of the tumor structure, tumors can be more easily distinguished after the injection of a contrast medium. In order to have more an effective method to increase the contrast-to-noise ratio (CNR), we applied a projection-based energy-weighting method. The purpose of this study is to demonstrate the feasibility of using the projection-based energy-weighting method in digital subtraction mammography. Unlike some other previous studies, we applied the projection-based energy-weighting method to more practical mammography conditions by using the Monte Carlo method to simulate four different iodine solutions embedded in a breast phantom comprised of 50% adipose and 50% glandular tissues. We also considered an optimal tube voltage and anode/filter combination in digital iodine contrast media mammography in order to maximize the figure-of-merit (FOM). The simulated source energy was from 20 to 45 keV to prevent electronic noise and include the k-edge energy of iodine (33.2 keV). The results showed that the projection-based energy-weighting improved the CNR by factors of 1.05 - 1.86 compared to the conventionally integrated images. Consequently, the CNR of digital subtraction mammography images can be improved by using projection-based energy-weighting with photon-counting detectors.

  9. High efficiency scintillation detectors

    International Nuclear Information System (INIS)

    Noakes, J.E.

    1976-01-01

    A scintillation counter consisting of a scintillation detector, usually a crystal scintillator optically coupled to a photomultiplier tube which converts photons to electrical pulses is described. The photomultiplier pulses are measured to provide information on impinging radiation. In inorganic crystal scintillation detectors to achieve maximum density, optical transparency and uniform activation, it has been necessary heretofore to prepare the scintillator as a single crystal. Crystal pieces fail to give a single composite response. Means are provided herein for obtaining such a response with crystal pieces, such means comprising the combination of crystal pieces and liquid or solid organic scintillator matrices having a cyclic molecular structure favorable to fluorescence. 8 claims, 6 drawing figures

  10. Scintillation counting apparatus

    International Nuclear Information System (INIS)

    Noakes, J.E.

    1978-01-01

    Apparatus is described for the accurate measurement of radiation by means of scintillation counters and in particular for the liquid scintillation counting of both soft beta radiation and gamma radiation. Full constructional and operating details are given. (UK)

  11. Direct Measurement of Tritium in Biological Materials with the Liquid Scintillation Counter; Determination quantitative directe du tritium dans les substances biologiques, au moyen de compteurs a scintillations a liquides; Neposredstvennoe izmerenie kolichestva tritiya v biologicheskikh materialakh pri pomoshchi zhidkogo stsintillyatsionnogo schetchika; Determinacion cuantitativa directa del tritio en sustancias biologicas mediante contadores de centelleador liquido

    Energy Technology Data Exchange (ETDEWEB)

    Halvorsen, K [Institutt for Atomenergi, Kjeller, Lillestroem (Norway)

    1962-01-15

    Procedures for measurement of tritium in animal tissues and isolated tissue fractions have been reported in the literature. In all the work reported, however, a liquid scintillation coincidence spectrometer has been used for the counting of the samples. In this work a single phototube liquid scintillation counter was used for the measurements. Investigation centred primarily on the direct dissolution of animal tissue in Hyamine 10-X and the suspension counting of lyophilized tissue in scintillating gels. Different tissues, such as liver, intestine, blood and skin, can be dissolved directly in Hyamine and measured with an efficiency of 10-15%. The techniques of quenching correction and certain phosphorescence phenomena as they affect the counting in a single phototube counting system are discussed. The sensitivity of the method, although somewhat less than that of the coincidence-counting arrangement, seems to be sufficient for many applications. The work reported was carried out on tissue samples from mice previously injected with tritium- labelled thymidine. When a dose of approximately 1 {mu}c tritiated thymidine per g of body weight was injected into the mice, the metabolic fate of the thymidine incorporated into deoxyribonucleic acid (DNA) of the various tissues could be followed for a period of one month. (author) [French] Diverses techniques de determination du tritium dans les tissus animaux et fractions isolees de tissus animaux ont deja ete decrites. Mais toutes comportent l'emploi d'un spectrometre de coincidences a scintillations a liquides pour le comptage des echantillons. Pour faire cette determination, l'auteur s'est servi d'un seul phototube-compteur a scintillations a liquides. Il a etudie surtout la dissolution directe de tissu animal dans de l'hyamine 10-X, et le comptage de tissus lyophilises en suspension dans des gels a scintillations. Certains tissus, tels que le foie, l'intestin, le sang et la peau, peuvent Etre dissous directement dans l

  12. Liquid scintillation solution

    International Nuclear Information System (INIS)

    Long, E.C.

    1976-01-01

    The invention deals with a liquid scintillation solution which contains 1) a scintillation solvent (toluol), 2) a primary scintillation solute (PPO), 3) a secondary scintillation solute (dimethyl POPOP), 4) several surfactants (iso-octyl-phenol polyethoxy-ethanol and sodium di-hexyl sulfosuccinate) essentially different from one another and 5) a filter resolution and/or transparent-making agent (cyclic ether, especially tetrahydrofuran). (HP) [de

  13. Spectral and spatial resolution properties of photon counting X-ray detectors like the Medipix-Detector; Spektrale und bildgebende Eigenschaften photonenzaehlender Roentgendetektoren am Beispiel des Medipix-Detektors

    Energy Technology Data Exchange (ETDEWEB)

    Korn, A.

    2007-05-14

    The Medipix detector is a hybrid photon counting X-ray detector, consisting of an ASIC and a semiconducting layer as the sensor. This makes the Medipix a direct converting detector. A special feature of the Medipix is a signal processing circuit in every single pixel. This circuit amplifies the input signal triggered by a photon and then transforms the pulse into a digital signal. This early stage digitalisation is one of the main advantages of the detector, since no dark currents are integrated into the signal. Furthermore, the energy information of each single photon is partly preserved. The high number of pixels lends the detector a wide dynamic range, starting from single counts up to a rate of 1010 photons per cm2 and second. Apart from the many advantages, there are still some problems with the detector. Some effects lead to a deterioration of the energy resolution as well as the spatial resolution. The main reasons for this are two effects occuring in the detector, charge sharing and backscattering inside the detector. This study investigates the influence of those two effects on both the energy and spatial resolution. The physical causes of these effects are delineated and their impact on the detector output is examined. In contrast to high energy photon detectors, the repulsion of the charge carriers drifting inside the sensor must not be neglected in a detailed model of X-ray detectors with an energy range of 5 keV-200 keV. For the simulation of the Medipix using Monte Carlo simulations, the software ROSI was augmented. The added features allow a detailed simulation of the charge distribution, using the relevant physical effects that alter the distribution width during the drift towards the sensor electrodes as well further influences on the detector output, including electronical noise, threshold noise or the geometry of the detector. The measured energy and spatial resolution of several different models of Medipix is compared to the simulated

  14. Cerenkov counting and Cerenkov-scintillation counting with high refractive index organic liquids using a liquid scintillation counter

    Energy Technology Data Exchange (ETDEWEB)

    Wiebe, L I; Helus, F; Maier-Borst, W [Deutsches Krebsforschungszentrum, Heidelberg (Germany, F.R.). Inst. fuer Nuklearmedizin

    1978-06-01

    /sup 18/F and /sup 14/C radioactivity was measured in methyl salicylate (MS), a high refractive index hybrid Cherenkov-scintillation generating medium, using a liquid scintillation counter. At concentrations of up to 21.4%, in MS, dimethyl sulfoxide (DMSO) quenched /sup 14/C fluorescence, and with a 10-fold excess of DMSO over MS, /sup 18/F count rates were reduced below that for DMSO alone, probably as a result of concentration-independent self-quenching due to 'dark-complex' formation. DMSO in lower concentrations did not reduce the counting efficiency of /sup 18/F in MS. Nitrobenzene was a concentration-dependent quencher for both /sup 14/C and /sup 18/F in MS. Chlorobenzene (CB) and DMSO were both found to be weak Cherenkov generators with /sup 18/F. Counting efficiencies for /sup 18/F in MS, CB, and DMSO were 50.3, 7.8 and 4.3% respectively in the coincidence counting mode, and 58.1, 13.0 and 6.8% in the singles mode. /sup 14/C efficiencies were 14.4 and 22.3% for coincidence and singles respectively, and 15.3 and 42.0% using a modern counter designed for coincidence and single photon counting. The high /sup 14/C and /sup 18/F counting efficiency in MS are discussed with respect to excitation mechanism, on the basis of quench and channels ratios changes observed. It is proposed that MS functions as an efficient Cherenkov-scintillation generator for high-energy beta emitters such as /sup 18/F, and as a low-efficiency scintillator for weak beta emitting radionuclides such as /sup 14/C.

  15. Cerenkov counting and Cerenkov-scintillation counting with high refractive index organic liquids using a liquid scintillation counter

    International Nuclear Information System (INIS)

    Wiebe, L.I.; Helus, F.; Maier-Borst, W.

    1978-01-01

    18 F and 14 C radioactivity was measured in methyl salicylate (MS), a high refractive index hybrid Cherenkov-scintillation generating medium, using a liquid scintillation counter. At concentrations of up to 21.4%, in MS, dimethyl sulfoxide (DMSO) quenched 14 C fluorescence, and with a 10-fold excess of DMSO over MS, 18 F count rates were reduced below that for DMSO alone, probably as a result of concentration-independent self-quenching due to 'dark-complex' formation. DMSO in lower concentrations did not reduce the counting efficiency of 18 F in MS. Nitrobenzene was a concentration-dependent quencher for both 14 C and 18 F in MS. Chlorobenzene (CB) and DMSO were both found to be weak Cherenkov generators with 18 F. Counting efficiencies for 18 F in MS, CB, and DMSO were 50.3, 7.8 and 4.3% respectively in the coincidence counting mode, and 58.1, 13.0 and 6.8% in the singles mode. 14 C efficiencies were 14.4 and 22.3% for coincidence and singles respectively, and 15.3 and 42.0% using a modern counter designed for coincidence and single photon counting. The high 14 C and 18 F counting efficiency in MS are discussed with respect to excitation mechanism, on the basis of quench and channels ratios changes observed. It is proposed that MS functions as an efficient Cherenkov-scintillation generator for high-energy beta emitters such as 18 F, and as a low-efficiency scintillator for weak beta emitting radionuclides such as 14 C. (author)

  16. Scintillator manufacture at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Mellott, K.; Bross, A.; Pla-Dalmau, A.

    1998-08-01

    A decade of research into plastic scintillation materials at Fermilab is reviewed. Early work with plastic optical fiber fabrication is revisited and recent experiments with large-scale commercial methods for production of bulk scintillator are discussed. Costs for various forms of scintillator are examined and new development goals including cost reduction methods and quality improvement techniques are suggested.

  17. WORKSHOP: Scintillating fibre detectors

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    Scintillating fibre detector development and technology for the proposed US Superconducting Supercollider, SSC, was the subject of a recent workshop at Fermilab, with participation from the high energy physics community and from industry. Sessions covered the current status of fibre technology and fibre detectors, new detector applications, fluorescent materials and scintillation compositions, radiation damage effects, amplification and imaging structures, and scintillation fibre fabrication techniques

  18. Liquid scintillation measurement. I

    International Nuclear Information System (INIS)

    Rexa, R.; Tykva, R.

    1983-01-01

    The individual components of scintillation solutions and their tasks are listed. Explained briefly is the scintillation process in a liquid scintillator. Factors are discussed which influence this process as are methods applied to supress their influence. They include: ionization quenching, quenching by dilution and concentration, chemical, colour, phase and photon quenching and single-photon events causing an undesirable backgorund. (M.D.)

  19. Scintillation response of organic and inorganic scintillators

    CERN Document Server

    Papadopoulos, L M

    1999-01-01

    A method to evaluate the scintillation response of organic and inorganic scintillators to different heavy ionizing particles is suggested. A function describing the rate of the energy consumed as fluorescence emission is derived, i.e., the differential response with respect to time. This function is then integrated for each ion and scintillator (anthracene, stilbene and CsI(Tl)) to determine scintillation response. The resulting scintillation responses are compared to the previously reported measured responses. Agreement to within 2.5% is observed when these data are normalized to each other. In addition, conclusions regarding the quenching parameter kB dependence on the type of the particle and the computed values of kB for certain ions are included. (author)

  20. WE-FG-207B-07: Feasibility of Low Dose Lung Cancer Screening with a Whole-Body Photon Counting CT: First Human Results

    International Nuclear Information System (INIS)

    Symons, R; Cork, T; Folio, L; Bluemke, D; Pourmorteza, A

    2016-01-01

    Purpose: To evaluate the feasibility of using a whole-body photon counting detector (PCD) CT scanner for low dose lung cancer screening compared to a conventional energy integrating detector (EID) system. Methods: Radiation dose-matched EID and PCD scans of the COPDGene 2 phantom and 2 human volunteers were acquired. Phantom images were acquired at different radiation dose levels (CTDIvol: 3.0, 1.5, and 0.75 mGy) and different tube voltages (120, 100, and 80 kVp), while human images were acquired at vendor recommended low-dose lung cancer screening settings. EID and PCD images were compared for quantitative Hounsfield unit accuracy, noise levels, and contrast-to-noise ratios (CNR) for detection of ground-glass nodules (GGNs) and emphysema. Results: The PCD Hounsfield unit accuracy was better for water at all scan parameters, and for lung, GGN and emphysema equivalent regions of interest (ROIs) at 1.5 and 0.75 mGy. PCD attenuation accuracy was more consistent for all scan parameters (all P<0.01), while Hounsfield units for lung, GGN and emphysema ROIs changed significantly for EID with decreasing dose (all P<0.001). PCD showed lower noise levels at the lowest dose setting at 120, 100 and 80 kVp (15.2±0.3 vs 15.8±0.2, P=0.03; 16.1±0.3 vs 18.0±0.4, P=0.003; and 16.1±0.3 vs 17.9±0.3, P=0.001, respectively), resulting in superior CNR for the detection of GGNs and emphysema at 100 and 80 kVp. Significantly lower PCD noise levels were confirmed in volunteer images. Conclusion: PCD provided better Hounsfield unit accuracy for lung, ground-glass, and emphysema-equivalent foams at 1.5 and 0.75 mGy with less variability than EID. Additionally, PCD showed less noise, and higher CNR at 0.75 mGy for both 100 and 80 kVp. PCD technology may help reduce radiation exposure in lung cancer screening while maintaining diagnostic quality.

  1. WE-FG-207B-07: Feasibility of Low Dose Lung Cancer Screening with a Whole-Body Photon Counting CT: First Human Results

    Energy Technology Data Exchange (ETDEWEB)

    Symons, R; Cork, T; Folio, L; Bluemke, D; Pourmorteza, A [National Institutes of Health Clinical Center, Bethesda, MD (United States)

    2016-06-15

    Purpose: To evaluate the feasibility of using a whole-body photon counting detector (PCD) CT scanner for low dose lung cancer screening compared to a conventional energy integrating detector (EID) system. Methods: Radiation dose-matched EID and PCD scans of the COPDGene 2 phantom and 2 human volunteers were acquired. Phantom images were acquired at different radiation dose levels (CTDIvol: 3.0, 1.5, and 0.75 mGy) and different tube voltages (120, 100, and 80 kVp), while human images were acquired at vendor recommended low-dose lung cancer screening settings. EID and PCD images were compared for quantitative Hounsfield unit accuracy, noise levels, and contrast-to-noise ratios (CNR) for detection of ground-glass nodules (GGNs) and emphysema. Results: The PCD Hounsfield unit accuracy was better for water at all scan parameters, and for lung, GGN and emphysema equivalent regions of interest (ROIs) at 1.5 and 0.75 mGy. PCD attenuation accuracy was more consistent for all scan parameters (all P<0.01), while Hounsfield units for lung, GGN and emphysema ROIs changed significantly for EID with decreasing dose (all P<0.001). PCD showed lower noise levels at the lowest dose setting at 120, 100 and 80 kVp (15.2±0.3 vs 15.8±0.2, P=0.03; 16.1±0.3 vs 18.0±0.4, P=0.003; and 16.1±0.3 vs 17.9±0.3, P=0.001, respectively), resulting in superior CNR for the detection of GGNs and emphysema at 100 and 80 kVp. Significantly lower PCD noise levels were confirmed in volunteer images. Conclusion: PCD provided better Hounsfield unit accuracy for lung, ground-glass, and emphysema-equivalent foams at 1.5 and 0.75 mGy with less variability than EID. Additionally, PCD showed less noise, and higher CNR at 0.75 mGy for both 100 and 80 kVp. PCD technology may help reduce radiation exposure in lung cancer screening while maintaining diagnostic quality.

  2. A Monte Carlo simulation study of an improved K-edge log-subtraction X-ray imaging using a photon counting CdTe detector

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngjin, E-mail: radioyoungj@gmail.com [Department of Radiological Science, Eulji University, 553, Sanseong-daero, Sujeong-gu, Seongnam-si, Gyeonggi-do (Korea, Republic of); Lee, Amy Candy [Department of Mathematics and Statistics, McGill University (Canada); Kim, Hee-Joung [Department of Radiological Science and Radiation Convergence Engineering, Yonsei University (Korea, Republic of)

    2016-09-11

    Recently, significant effort has been spent on the development of photons counting detector (PCD) based on a CdTe for applications in X-ray imaging system. The motivation of developing PCDs is higher image quality. Especially, the K-edge subtraction (KES) imaging technique using a PCD is able to improve image quality and useful for increasing the contrast resolution of a target material by utilizing contrast agent. Based on above-mentioned technique, we presented an idea for an improved K-edge log-subtraction (KELS) imaging technique. The KELS imaging technique based on the PCDs can be realized by using different subtraction energy width of the energy window. In this study, the effects of the KELS imaging technique and subtraction energy width of the energy window was investigated with respect to the contrast, standard deviation, and CNR with a Monte Carlo simulation. We simulated the PCD X-ray imaging system based on a CdTe and polymethylmethacrylate (PMMA) phantom which consists of the various iodine contrast agents. To acquired KELS images, images of the phantom using above and below the iodine contrast agent K-edge absorption energy (33.2 keV) have been acquired at different energy range. According to the results, the contrast and standard deviation were decreased, when subtraction energy width of the energy window is increased. Also, the CNR using a KELS imaging technique is higher than that of the images acquired by using whole energy range. Especially, the maximum differences of CNR between whole energy range and KELS images using a 1, 2, and 3 mm diameter iodine contrast agent were acquired 11.33, 8.73, and 8.29 times, respectively. Additionally, the optimum subtraction energy width of the energy window can be acquired at 5, 4, and 3 keV for the 1, 2, and 3 mm diameter iodine contrast agent, respectively. In conclusion, we successfully established an improved KELS imaging technique and optimized subtraction energy width of the energy window, and based on

  3. Measurement of light emission in scintillation vials

    International Nuclear Information System (INIS)

    Duran Ramiro, M. Teresa; Garcia-Torano, Eduardo

    2005-01-01

    The efficiency and energy resolution of liquid scintillation counting (LSC) systems are strongly dependent on the optical characteristics of scintillators, vials, and reflectors. This article presents the results of measurements of the light-emission profile of scintillation vials. Two measurement techniques, autoradiographs and direct measurements with a photomultiplier tube, have been used to obtain light-emission distribution for standard vials of glass, etched glass and polyethylene. Results obtained with both techniques are in good agreement. For the first time, the effect of the meniscus in terms of light contribution has been numerically estimated. These results can help design LSC systems that are more efficient in terms of light collection

  4. Geophysical analysis of coherent satellite scintillation data

    Science.gov (United States)

    Fremouw, E. J.; Lansinger, J. M.; Miller, D. A.

    1981-11-01

    In May of 1976, Air Force Satellite P76-5 was launched with the Defense Nuclear Agency's Wideband beacon, DNA-002, as its sole payload. Several researchers have employed the resulting data in studies of ionospheric structure and its effect on transionospheric radio communications. In the present work, recordings of amplitude and phase scintillation imposed on Wideband's VHF and UHF signals by the ionosphere have been used to study medium-scale structures in the auroral-zone F layer. Results include quantitative identification of a very close relationship between scintillation and solar/geomagnetic activity, together with lack of a seasonal variation in scintillation activity in the Alaskan sector. A surprisingly high correlation (90%) was found between monthly means of phase-scintillation index, on the one hand, and sunspot number and 10-cm solar radio flux, on the other. The high-latitude scintillation boundary was found to be very similar to the soft-electron precipitation boundary, including similarity in expansion rates with increasing magnetic activity. Interestingly, it is systematically shifted poleward of the precipitation boundary on the day side of the earth and equatorward on the night side. Taken together, the results of this research disclose a rather direct relationship between scintillation and soft-electron precipitation, with plasma convection likely playing an important role in generation of the scintillation-producing irregularities.

  5. Scintillator material. Szintillatormaterial

    Energy Technology Data Exchange (ETDEWEB)

    Siegmund, M; Bendig, J; Regenstein, W

    1987-11-25

    A scintillator material for detection and quantitative determination of ionizing radiation is discussed consisting of an acridone dissolved in a fluid or solid medium. Solvent mixtures with at least one protogenic component or polymers and copolymers are used. The scintillator material is distinguished by an excellent stability at high energy doses.

  6. A helical scintillating fiber hodoscope

    CERN Document Server

    Altmeier, M; Bisplinghoff, J; Bissel, T; Bollmann, R; Busch, M; Büsser, K; Colberg, T; Demiroers, L; Diehl, O; Dohrmann, F; Engelhardt, H P; Eversheim, P D; Felden, O; Gebel, R; Glende, M; Greiff, J; Gross, A; Gross-Hardt, R; Hinterberger, F; Jahn, R; Jeske, M; Jonas, E; Krause, H; Lahr, U; Langkau, R; Lindemann, T; Lindlein, J; Maier, R; Maschuw, R; Mayer-Kuckuck, T; Meinerzhagen, A; Naehle, O; Pfuff, M; Prasuhn, D; Rohdjess, H; Rosendaal, D; Von Rossen, P; Sanz, B; Schirm, N; Schulz-Rojahn, M; Schwarz, V; Scobel, W; Thomas, S; Trelle, H J; Weise, E; Wellinghausen, A; Wiedmann, W; Woller, K; Ziegler, R

    1999-01-01

    A novel scintillating fiber hodoscope in helically cylindric geometry has been developed for detection of low multiplicity events of fast protons and other light charged particles in the internal target experiment EDDA at the Cooler Synchrotron COSY. The hodoscope consists of 640 scintillating fibers (2.5 mm diameter), arranged in four layers surrounding the COSY beam pipe. The fibers are helically wound in opposing directions and read out individually using 16-channel photomultipliers connected to a modified commercial encoding system. The detector covers an angular range of 9 deg. <= THETA<=72 deg. and 0 deg. <=phi (cursive,open) Greek<=360 deg. in the lab frame. The detector length is 590 mm, the inner diameter 161 mm. Geometry and granularity of the hodoscope afford a position resolution of about 1.3 mm. The detector design took into consideration a maximum of reliability and a minimum of maintenance. An LED array may be used for monitoring purposes. (author)

  7. Design and test of a high resolution plastic scintillating fiber detector with intensified CCD readout

    International Nuclear Information System (INIS)

    Rebourgeard, P.

    1991-01-01

    We present the design of a particle detector involving a coherent array of 100 000 plastic scintillating microfibers, with an individual core diameter around 50 micrometers, and an intensified bidimensional CCD array. We investigate both theoretically and experimentally the use of polystyrene based scintillators in optical multimodal fibers. The isotropic excitation of modes and the characteristics of energy transfers between the polystyrene matrix and the added fluorescent dyes are of particular interest. An experimental approach is proposed and applied to the development of a new binary scintillator. In order to study the transmission of the signal from the interaction area to the output face, we specify the loss factors, the resolution and the signal to noise ratio within the fiber array. The low light level at the output face of the detector leads us to use image intensifiers in photon counting mode. This requires a detailed analysis of resolutions, gain, noise and detectivity concepts. We propose to describe these strongly correlated notions by the moment generation formalism. Thus, a previous modelisation of the photoelectronic devices allows us to evaluate the performance of the readout chain. A complete detector has been assembled and tested on a high energy hadron beam; the measurements are in good agreement with the modelisation [fr

  8. Performance study of Philips digital silicon photomultiplier coupled to scintillating crystals

    CERN Document Server

    Liu, Z.; Auffray, E.; Lecoq, P.; Paganoni, M.

    2016-01-01

    Silicon photomultipliers (SiPMs) and scintillators are often arranged in the shape of arrays in Positron Emission Tomography (PET) systems. Digital SiPMs provide signal readout in single photon avalanche diode (SPAD) level. From the photon count rate measurement of each SPAD cell of digital SiPM, we found that the output scintillating photons distribute in an area larger than the scintillator physical coupling area. Taking advantage of the possibility to enable/disable individual cells of the digital SiPM, a group of Lutetium-yttrium oxyorthosilicate (LYSO) crystals with different dimensions coupled to a digital SiPM was used to study the influence of using different SiPM active area on the number of photons detected, energy resolution and coincidence time resolution (CTR). For the same crystal coupled to the digital SiPM, the larger the active area of digital SiPM, the higher the number of photons detected. The larger active area of the digital SiPM also results in a better energy resolution after saturation...

  9. Cryogenic scintillation properties of n-type GaAs for the direct detection of MeV/c2 dark matter

    Science.gov (United States)

    Derenzo, S.; Bourret, E.; Hanrahan, S.; Bizarri, G.

    2018-03-01

    This paper is the first report of n-type GaAs as a cryogenic scintillation radiation detector for the detection of electron recoils from interacting dark matter (DM) particles in the poorly explored MeV/c2 mass range. Seven GaAs samples from two commercial suppliers and with different silicon and boron concentrations were studied for their low temperature optical and scintillation properties. All samples are n-type even at low temperatures and exhibit emission between silicon donors and boron acceptors that peaks at 1.33 eV (930 nm). The lowest excitation band peaks at 1.44 eV (860 nm), and the overlap between the emission and excitation bands is small. The X-ray excited luminosities range from 7 to 43 photons/keV. Thermally stimulated luminescence measurements show that n-type GaAs does not accumulate metastable radiative states that could cause afterglow. Further development and use with cryogenic photodetectors promises a remarkable combination of large target size, ultra-low backgrounds, and a sensitivity to electron recoils of a few eV that would be produced by DM particles as light as a few MeV/c2.

  10. A gamma-ray discriminating neutron scintillator

    International Nuclear Information System (INIS)

    Eschbach, P.A.; Miller, S.D.; Cole, M.C.

    1994-01-01

    A neutron scintillator has been developed at Pacific Northwest Laboratory which responds directly to as little as 10 mrem/hour dose equivalent rate fast neutron fields. The scintillator is composed of CaF 2 :Eu or of NaI grains within a silicone rubber or polystyrene matrix, respectively. Neutrons colliding with the plastic matrix provide knockon protons, which in turn deposit energy within the grains of phosphor to produce pulses of light. Neutron interactions are discriminated from gamma-ray events on the basis of pulse height. Unlike NE-213 liquid scintillators, this solid scintillator requires no pulseshape discrimination and therefore requires less hardware. Neutron events are anywhere from two to three times larger than the gamma-ray exposures are compared to 0.7 MeV gamma-ray exposures. The CaF 2 :Eu/silicone rubber scintillator is nearly optically transparent, and can be made into a very sizable detector (4 cm x 1.5 cm) without degrading pulse height. This CaF 2 :Eu scintillator has been observed to have an absolute efficiency of 0.1% when exposed to 5-MeV accelerator-generated neutrons (where the absolute efficiency is the ratio of observed neutron events divided by the number of fast neutrons striking the detector)

  11. Methods for the continuous production of plastic scintillator materials

    Science.gov (United States)

    Bross, Alan; Pla-Dalmau, Anna; Mellott, Kerry

    1999-10-19

    Methods for producing plastic scintillating material employing either two major steps (tumble-mix) or a single major step (inline-coloring or inline-doping). Using the two step method, the polymer pellets are mixed with silicone oil, and the mixture is then tumble mixed with the dopants necessary to yield the proper response from the scintillator material. The mixture is then placed in a compounder and compounded in an inert gas atmosphere. The resultant scintillator material is then extruded and pelletized or formed. When only a single step is employed, the polymer pellets and dopants are metered into an inline-coloring extruding system. The mixture is then processed under a inert gas atmosphere, usually argon or nitrogen, to form plastic scintillator material in the form of either scintillator pellets, for subsequent processing, or as material in the direct formation of the final scintillator shape or form.

  12. Liquid-helium scintillation detection with germanium photodiodes

    International Nuclear Information System (INIS)

    Luke, P.N.; Haller, E.E.; Steiner, H.M.

    1982-05-01

    Special high-purity germanium photodiodes have been developed for the direct detection of vacuum ultraviolet scintillations in liquid helium. The photodiodes are immersed in the liquid helium, and scintillations are detected through one of the bare sides of the photodiodes. Test results with scintillation photons produced by 5.3-MeV α particles are presented. The use of these photodiodes as liquid-helium scintillation detectors may offer substantial improvements over the alternate detection method requiring the use of wavelength shifters and photomultiplier tubes

  13. Investigations of X-ray response of single wire anode Ar-N2 flow type gas scintillation proportional counters

    International Nuclear Information System (INIS)

    Garg, S.P.; Sharma, R.C.

    1984-01-01

    The X-ray response of single wire anode gas scintillation proportional counters of two different geometries operated with argon+nitrogen gases in continuous flow has been investigated with wire anodes of diameters 25 μm to 1.7 mm. An energy resolution of 19% is obtained for 5.9 keV X-rays entering the counter perpendicular to the anode in pill-box geometry with 25 μm diameter anode. With cylindrical geometry counters energy obtained at 5.9 keV are 18%, 24% and 33% for 50 μm, 0.5 mm and 1.7 mm diameter anodes respectively. An analysis of the observed resolution shows that the contribution from photon counting statistics to the relative variance of scintillation pulses even for X-rays in Ar-N 2 single wire anode gas scintillation proportional counters is small and is not a limiting factor. The energy resolution with thicker anodes, where the contribution from the variance of the charge multiplication factor also has been minimised, is found to deteriorate mainly by the interaction in the scintillation production region. Comments are made on the possibility of improvement in energy resolution by suppression of pulses due to such interactions with the help of the pulse risetime discrimination technique. (orig.)

  14. Liquid scintillation alpha spectrometry techniques

    International Nuclear Information System (INIS)

    McKlveen, J.W.; McDowell, W.J.

    1984-01-01

    Accurate, quantitative determinations of alpha emitting nuclides by conventional plate counting methods are difficult, because of sample self-absorption problems in counting and because of non-reproducible losses in conventional sample separation methods. Liquid scintillation alpha spectrometry offers an attractive alternative with no sample self-absorption or geometry problems and with 100% counting efficiency. Sample preparation may include extraction of the alpha emitter of interest by a specific organic phase-soluble compound directly into the liquid scintillation counting medium. Detection electronics use energy and pulse-shape discrimination, to yield alpha spectra without beta and gamma background interference. Specific procedures have been developed for gross alpha, uranium, plutonium, thorium and colonium assay. Possibilities for a large number of other applications exist. Accuracy and reproducibility are typically in the 1% range. Backgrounds of the order of 0.01 cpm are readily achievable. The paper will present an overview of liquid scintillation alpha counting techniques and some of the results achieved for specific applications. (orig.)

  15. Some history of liquid scintillator development at Los Alamos

    International Nuclear Information System (INIS)

    Ott, D.G.

    1979-01-01

    The early developments in liquid scintillation counting made at Los Alamos Scientific Laboratory are reviewed. Most of the work was under the direction of F.N. Hayes and included counter development and applications as well as synthesis and chemistry of liquid scintillators

  16. WE-FG-207B-01: BEST IN PHYSICS (IMAGING): Abdominal CT with Three K-Edge Contrast Materials Using a Whole-Body Photon-Counting Scanner: Initial Results of a Large Animal Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Lakshmanan, M; Symons, R; Cork, T; Davies-Venn, C; Rice, K; Malayeri, A; Sandfort, V; Bluemke, D; Pourmorteza, A [National Institutes of Health Clinical Center, Bethesda, MD (United States)

    2016-06-15

    Purpose: To demonstrate the feasibility of in vivo three-material decomposition techniques using photon-counting CT (PCCT) with possible advantage of resolving arterial and venous flow of an organ simultaneously. Methods: Abdominal PCCT scans were acquired using a prototype whole-body PCCT with four energy thresholds (25/50/75/90keV) in a canine. Bismuth subsalicylate (60 mg) was administered orally one day prior to scanning. Immediately prior to CT scan, gadoteric acid (60 ml, Dotarem, Guerbet) was intravenously injected, followed in ten minutes by a 20mL injection of iodinated contrast (iopamidol 370 mg/mL, Bracco). Scans were acquired every ∼20 seconds, starting from the time of iodine injection. Linear material decomposition was performed using the least mean squares method to create concentration maps of iodine, gadolinium, and bismuth. The method was calibrated to vials with known concentrations of materials placed next to the animal. The accuracy of this method was tested on vials with known concentrations. Results: The material decomposition algorithm’s accuracy was confirmed to be within ±4mM in the test vials. In the animal, we could estimate the concentration of gadolinium in delayed-enhanced phase (10 minutes post-injection) in the abdomen. We could follow the wash-in and wash-out of iodine in arterial, venous, and excretory flow of the kidneys (20s, 80s, and 120s post-iodine injection) while gadolinium was present in the delayed-enhanced phase. Bismuth, which was used as a contrast agent for the gastro-intestinal tract, was easily differentiable from the other two contrast agents in the small intestine. Conclusion: This study shows the feasibility of using photon-counting CT with four energy thresholds to differentiate three k-edge contrast agents in vivo. This can potentially reduce radiation dose to patients by combining arterial and venous phases into a single acquisition.

  17. Phosphor scintillator structure

    International Nuclear Information System (INIS)

    Cusano, D.A.; Prener, J.S.

    1980-01-01

    A method of fabricating scintillators is described in which the phosphor is distributed within the structure in such a way as to enhance the escape of the visible wavelength radiation that would otherwise be dissipated within the scintillator body. Two embodiments of the present invention are disclosed: one in which the phosphor is distributed in a layered structure and another in which the phosphor is dispersed throughout a transparent matrix. (U.K.)

  18. Scintillating properties of frozen new liquid scintillators

    CERN Document Server

    Britvich, G I; Golovkin, S V; Martellotti, G; Medvedkov, A M; Penso, G; Soloviev, A S; Vasilchenko, V G

    1999-01-01

    The light emission from scintillators which are liquid at room temperature was studied in the interval between $+20$~$^{\\circ}$C and $-120$~$^{\\circ}$C, where the phase transition from liquid to solid takes place. The light yield measured at $-120$~$^{\\circ}$C is about twice as much as that observed at $+20$~$^{\\circ}$C. By cooling the scintillator from $+20$~$^{\\circ}$C to $-120$~$^{\\circ}$C and then heating it from $-120$~$^{\\circ}$C to $+20$~$^{\\circ}$C, the light yield varies in steps at well defined temperatures, which are different for the cooling and heating processes. These hysteresis phenomena appear to be related to the solvent rather than to the dopant. The decay time of scintillation light was measured at $+20$~$^{\\circ}$C and $-120$~$^{\\circ}$C. Whilst at room temperature most of the light is emitted with a decay time of 6--8 ns, at $-120$~$^{\\circ}$C a slower component, with a decay time of 25--35 ns, becomes important.

  19. Applications of low level liquid scintillation counting

    International Nuclear Information System (INIS)

    Noakes, J.E.

    1983-01-01

    Low level liquid scintillation counting is reviewed in terms of its present use and capabilities for measuring low activity samples. New areas of application of the method are discussed with special interest directed to the food industry and environmental monitoring. Advantages offered in the use of a low background liquid scintillation counter for the nuclear power industry and nuclear navy are discussed. Attention is drawn to the need for commercial development of such instrumentation to enable wider use of the method. A user clientele is suggested as is the required technology to create such a counter

  20. Neutron energy response measurement of scintillation detectors

    International Nuclear Information System (INIS)

    Yang Hongqiong; Peng Taiping; Yang Jianlun; Tang Zhengyuan; Yang Gaozhao; Li Linbo; Hu Mengchun; Wang Zhentong; Zhang Jianhua; Li Zhongbao; Wang Lizong

    2004-01-01

    Neutron sensitivities of detectors composed of plastic scintillator ST401, ST1422, ST1423 and phyotomultiplier tube in primary energy range of fission neutron are calibrated by direct current. The energy response curve of the detectors is obtained in this experiment. The experimental result has been compared with the theoretical calculation and they are in agreement within measuring uncertainty. (authors)

  1. Scintillation counting: an extrapolation into the future

    International Nuclear Information System (INIS)

    Ross, H.H.

    1983-01-01

    Progress in scintillation counting is intimately related to advances in a variety of other disciplines such as photochemistry, photophysics, and instrumentation. And while there is steady progress in the understanding of luminescent phenomena, there is a virtual explosion in the application of semiconductor technology to detectors, counting systems, and data processing. The exponential growth of this technology has had, and will continue to have, a profound effect on the art of scintillation spectroscopy. This paper will review key events in technology that have had an impact on the development of scintillation science (solid and liquid) and will attempt to extrapolate future directions based on existing and projected capability in associated fields. Along the way there have been occasional pitfalls and several false starts; these too will be discussed as a reminder that if you want the future to be different than the past, study the past

  2. Current trends in scintillator detectors and materials

    International Nuclear Information System (INIS)

    Moses, W.W.

    2002-01-01

    The last decade has seen a renaissance in inorganic scintillator development for gamma ray detection. Lead tungstate (PbWO 4 ) has been developed for high-energy physics experiments, and possesses exceptionally high density and radiation hardness, albeit with low luminous efficiency. Lutetium orthosilicate or LSO (Lu 2 SiO 5 :Ce) possesses a unique combination of high luminous efficiency, high density, and reasonably short decay time, and is now incorporated in commercial positron emission tomography cameras. There have been advances in understanding the fundamental mechanisms that limit energy resolution, and several recently discovered materials (such as LaBr 3 :Ce) possess energy resolution that approaches that of direct solid state detectors. Finally, there are indications that a neglected class of scintillator materials that exhibit near band-edge fluorescence could provide scintillators with sub-nanosecond decay times and high luminescent efficiency

  3. Optics study of liquid scintillation counting systems

    International Nuclear Information System (INIS)

    Duran Ramiro, M. T.; Garcia-Torano, E.

    2005-01-01

    Optics is a key issue in the development of any liquid scintillation counting (LSC) system. Light emission in the scintillating solution, transmission through the vial and reflector design are some aspects that need to be considered in detail. This paper describes measurements and calculations carried out to optimise these factors for the design of a new family of LSC counters. Measurements of the light distribution emitted by a scintillation vial were done by autoradiographs of cylindrical vials made of various materials and results were compared to those obtained by direct measurements of the light distribution made by scanning the vial with a photomultiplier tube. Calculations were also carried out to study the light transmission in the vial and the optimal design of the reflector for a system with one photomultiplier tube. (Author)

  4. Inorganic liquid scintillator

    International Nuclear Information System (INIS)

    Pavlicek, Z.; Barta, C.; Jursova, L.

    1986-01-01

    An inorganic liquid scintillator is designed which contains 1 to 30 wt.% of an inorganic molecular compound as the basic active component; the compound contains a cation with an atomic number higher than 47 and a halogen anion. The basic inorganic component is dissolved in water or in an organic solvent in form of non-dissociated molecules or self-complexes in which the bond is preserved between the cation and anion components. The light yield from these scintillators ranges between 70 and 150% of the light yield of a standard organic scintillator based on toluene. They are advantageous in that that they allow to increase the water content in the sample to up to 100%. (M.D.)

  5. Physics of scintillation detectors

    International Nuclear Information System (INIS)

    Novotny, R.

    1991-01-01

    The general concept of a radiation detector is based on three fundamental principles: sensitivity of the device to the radiation of interest which requires a large cross-section in the detector material, detector response function to the physical properties of the radiation. As an example, a scintillation detector for charged particles should allow to identify the charge of the particle, its kinetic energy and the time of impact combined with optimum resolutions. Optimum conversion of the detector response (like luminescence of a scintillator) into electronical signals for further processing. The following article will concentrate on the various aspects of the first two listed principles as far as they appear to be relevant for photon and charged particle detection using organic and inorganic scintillation detectors. (orig.)

  6. Scintillator plate calorimetry

    International Nuclear Information System (INIS)

    Price, L.E.

    1990-01-01

    Calorimetry using scintillator plates or tiles alternated with sheets of (usually heavy) passive absorber has been proven over multiple generations of collider detectors. Recent detectors including UA1, CDF, and ZEUS have shown good results from such calorimeters. The advantages offered by scintillator calorimetry for the SSC environment, in particular, are speed (<10 nsec), excellent energy resolution, low noise, and ease of achieving compensation and hence linearity. On the negative side of the ledger can be placed the historical sensitivity of plastic scintillators to radiation damage, the possibility of nonuniform response because of light attenuation, and the presence of cracks for light collection via wavelength shifting plastic (traditionally in sheet form). This approach to calorimetry is being investigated for SSC use by a collaboration of Ames Laboratory/Iowa State University, Argonne National Laboratory, Bicron Corporation, Florida State University, Louisiana State University, University of Mississippi, Oak Ridge National Laboratory, Virginia Polytechnic Institute and State University, Westinghouse Electric Corporation, and University of Wisconsin

  7. Scintillation proximity assay

    International Nuclear Information System (INIS)

    Hart, H.

    1980-01-01

    In a method of immunological assay two different classes of particles which interact at short distances to produce characteristic detectable signals are employed in a modification of the usual latex fixation test. In one embodiment an aqueous suspension of antigen coated tritiated latex particles (LH) and antigen coated polystyrene scintillant particles (L*) is employed to assay antibody in the aqueous medium. The amount of (LH) (L*) dimer formation and higher order aggregation induced and therefore the concentration of antibody (or antigen) present which caused the aggregation can be determined by using standard liquid scintillation counting equipment. (author)

  8. Microfluidic Scintillation Detectors

    CERN Multimedia

    Microfluidic scintillation detectors are devices of recent introduction for the detection of high energy particles, developed within the EP-DT group at CERN. Most of the interest for such technology comes from the use of liquid scintillators, which entails the possibility of changing the active material in the detector, leading to an increased radiation resistance. This feature, together with the high spatial resolution and low thickness deriving from the microfabrication techniques used to manufacture such devices, is desirable not only in instrumentation for high energy physics experiments but also in medical detectors such as beam monitors for hadron therapy.

  9. Preparation and performance study of a novel liquid scintillator with mixed solvent as the matrix

    International Nuclear Information System (INIS)

    Zheng, Zhanlong; Zhu, Jiayi; Luo, Xuan; Xu, Yewei; Zhang, Qianfeng; Zhang, Xing; Bi, Yutie; Zhang, Lin

    2017-01-01

    A novel liquid scintillator with the mixed solvent as the matrix was prepared for obtaining a good comprehensive performance. In this ternary liquid scintillator, the combination of 20% pseudocumene (PC) and 80% linear-alkyl benzene (LAB) by volume was chosen as the mixed solvent, and 2,5-diphenyloxazole (PPO) and 1,4-bis(2-Methylstyryl) benzene (bis-MSB) were as the primary fluor and wavelength shifter, respectively. The optimum prescription was obtained with regard to the light yield. Some characterizations based on the optimal formulation were conducted. The fluorescence emission spectra and wavelength-dependent optical attenuation length of the sample were measured by the fluorescence spectrophotometer and an UV–Vis spectrometer, respectively. The light yield was characterized by adopting the home-made optical platform device. The decay time was tested by adopting the time-correlated single photon counting (TCSPC) technique featured in high dynamic range of several orders of magnitude in light intensity. The experimental test results showed that the sample had a fairly good comprehensive performance.

  10. Preparation and performance study of a novel liquid scintillator with mixed solvent as the matrix

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Zhanlong [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, Mianyang 621010 (China); Zhu, Jiayi [Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, Mianyang 621010 (China); Luo, Xuan, E-mail: luox76@gmail.com [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Xu, Yewei [School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Zhang, Qianfeng [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, Mianyang 621010 (China); Zhang, Xing [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Bi, Yutie, E-mail: biyutie@sina.com [Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, Mianyang 621010 (China); Zhang, Lin [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology and Research Center of Laser Fusion, Mianyang 621010 (China)

    2017-04-01

    A novel liquid scintillator with the mixed solvent as the matrix was prepared for obtaining a good comprehensive performance. In this ternary liquid scintillator, the combination of 20% pseudocumene (PC) and 80% linear-alkyl benzene (LAB) by volume was chosen as the mixed solvent, and 2,5-diphenyloxazole (PPO) and 1,4-bis(2-Methylstyryl) benzene (bis-MSB) were as the primary fluor and wavelength shifter, respectively. The optimum prescription was obtained with regard to the light yield. Some characterizations based on the optimal formulation were conducted. The fluorescence emission spectra and wavelength-dependent optical attenuation length of the sample were measured by the fluorescence spectrophotometer and an UV–Vis spectrometer, respectively. The light yield was characterized by adopting the home-made optical platform device. The decay time was tested by adopting the time-correlated single photon counting (TCSPC) technique featured in high dynamic range of several orders of magnitude in light intensity. The experimental test results showed that the sample had a fairly good comprehensive performance.

  11. Liquid scintillation, counting, and compositions

    International Nuclear Information System (INIS)

    Sena, E.A.; Tolbert, B.M.; Sutula, C.L.

    1975-01-01

    The emissions of radioactive isotopes in both aqueous and organic samples can be measured by liquid scintillation counting in micellar systems. The micellar systems are made up of scintillation solvent, scintillation solute and a mixture of surfactants, preferably at least one of which is relatively oil-soluble water-insoluble and another which is relatively water-soluble oil-insoluble

  12. Scintillation properties of acrylate based plastic scintillator by photoploymerization method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Hwan [Dept. of Radiological Science, Cheongju University, Cheongju (Korea, Republic of); Lee, Joo Il [Dept. of of Radiology, Daegu Health College, Daegu (Korea, Republic of)

    2016-12-15

    In this study, we prepared and characterized a acrylate based UV-curable plastic scintillator. It was used co-polymers TMPTA, DHPA and Ultima GoldTM LLT organic scintillator. The emission spectrum of the plastic scintillator was located in the range of 380⁓520 nm, peaking at 423 nm. And the scintillator is more than 50% transparent in the range of 400⁓ 800 nm. The emission spectrum is well match to the quantum efficiency of photo-multiplier tube and the fast decay time of the scintillation is 12 ns, approximately. This scintillation material provides the possibility of combining 3D printing technology, and then the applications of the plastic scintillator may be expected in human dosimetry etc.

  13. Polysiloxane scintillator composition

    Science.gov (United States)

    Walker, J.K.

    1992-05-05

    A plastic scintillator useful for detecting ionizing radiation comprising a matrix which comprises an optically transparent polysiloxane having incorporated therein at least one ionizing radiation-hard fluor capable of converting electromagnetic energy produced in the polysiloxane upon absorption of ionizing radiation to detectable light.

  14. WORKSHOP: Scintillating crystals

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1992-12-15

    Scintillating crystals are one of the big spinoff success stories of particle physics, and from 22-26 September an international workshop in Chamonix in the French Alps looked at the increasing role of these materials in pure and applied science and in industry.

  15. Radiopharmaceuticals for bone scintillators

    International Nuclear Information System (INIS)

    Rey, A.M.

    1994-01-01

    One of the diagnostic techniques used in nuclear medicine is the bone scintiscanning with labelled compounds for obtain skeletal images. The main sections in this work are: (1) bone composition and anatomy;(2)skeletal radiopharmaceutical development;(3)physical properties of radionuclides;(4)biological behaviour and chemical structures;(5)radiopharmaceuticals production for skeletal scintillation;(6)kits;(7)dosimetry and toxicity.tabs

  16. WORKSHOP: Scintillating crystals

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    Scintillating crystals are one of the big spinoff success stories of particle physics, and from 22-26 September an international workshop in Chamonix in the French Alps looked at the increasing role of these materials in pure and applied science and in industry

  17. Economical stabilized scintillation detector

    International Nuclear Information System (INIS)

    Anshakov, O.M.; Chudakov, V.A.; Gurinovich, V.I.

    1983-01-01

    An economical scintillation detector with the stabilization system of an integral type is described. Power consumed by the photomultiplier high-voltage power source is 40 mW, energy resolution is not worse than 9%. The given detector is used in a reference detector of a digital radioisotope densimeter for light media which is successfully operating for several years

  18. Thallium bromide photodetectors for scintillation detection

    CERN Document Server

    Hitomi, K; Shoji, T; Hiratate, Y; Ishibashi, H; Ishii, M

    2000-01-01

    A wide bandgap compound semiconductor, TlBr, has been investigated as a blue sensitive photodetector material for scintillation detection. The TlBr photodetectors have been fabricated from the TlBr crystals grown by the TMZ method using materials purified by many pass zone refining. The performance of the photodetectors has been evaluated by measuring their leakage current, quantum efficiency, spatial uniformity, direct X-ray detection and scintillation detection characteristics. The photodetectors have shown high quantum efficiency for the blue wavelength region and high spatial uniformity for their optical response. In addition, good direct X-ray detection characteristics with an energy resolution of 4.5 keV FWHM for 22 keV X-rays from a sup 1 sup 0 sup 9 Cd radioactive source have been obtained. Detection of blue scintillation from GSO and LSO scintillators irradiated with a sup 2 sup 2 Na radioactive source has been done successfully by using the photodetectors at room temperature. A clear full-energy pea...

  19. Application of time-correlated single photon counting and stroboscopic detection methods with an evanescent-wave fibre-optic sensor for fluorescence-lifetime-based pH measurements

    International Nuclear Information System (INIS)

    Henning, Paul E; Geissinger, Peter

    2012-01-01

    Quasi-distributed optical fibre sensor arrays containing luminescent sensor molecules can be read out spatially resolved utilizing optical time-of-flight detection (OTOFD) methods, which employ pulsed laser interrogation of the luminosensors and time-resolved detection of the sensor signals. In many cases, sensing is based on a change in sensor luminescence intensity; however, sensing based on luminescence lifetime changes is preferable because it reduces the need for field calibration. Because in OTOFD detection is time-resolved, luminescence-lifetime information is already available through the signal pulses, although in practise applications were restricted to sensors with long luminescence lifetimes (hundreds of ns). To implement lifetime-based sensing in crossed-optical-fibre-sensor arrays for sensor molecules with lifetimes less than 10 ns, two time-domain methods, time-correlated single photon counting and stroboscopic detection, were used to record the pH-dependent emission of a fluorescein derivative covalently attached to a highly-porous polymer. A two-term nonexponential decay function yielded both a good fit for experimental lifetime data during reconvolution and a pH response that matches Henderson–Hasselbalch behaviour, yielding a sensor accuracy of 0.02 pH units. Moreover, strong agreement was obtained for the two lifetime determination methods and with intensity-based measurements taken previously. (paper)

  20. Performance of molded plastic scintillators

    International Nuclear Information System (INIS)

    Gen, N.S.; Leman, V.E.; Solomonov, V.M.

    1989-01-01

    The performance of molded plastic scintillators is studied. The plastic scintillators studied were formed by transfer molding and intrusion from a scintillation composition consisting of polystyrene and a standard system of luminescent additives: 2 mass % of paraterphenyl + 0.06 mass % 1,4-di-/2-[5-phenyloxazoyly]/benzene and a plasticizer. The combined effect of mechanical load and temperature was studied. The effect of radiation on molded plastic scintillators was studied using gamma radiation from a 60 Co source. The studies show that the main operating characteristics of molded plastic scintillators are on a par with those of polymerized plastic scintillators. At the same time, molded plastic scintillators are superior in thermal stability at temperatures below the glass transition temperature and with respect to their working temperature range

  1. The Optimum Condition For Determination Of Radioactivity Of Pest Insects Labelled with P-32 By Using Liquid scintillation Counter

    International Nuclear Information System (INIS)

    Yarianto, S.; Susilo, Budi; Sutrisno, Singgih

    2002-01-01

    Tracer technique is needed in the control programe of pest insects especially for determining of its direction and dispersal. Radioisotopes of P-32 is frecuently used for labeling of pest insects. Liquid Scintillation Counter can be used effectively for measuring radioactivity of pest insects labelled by P-32. Optilnization of liquid compositions that consist of solvents. primary scintillation PPO and secondary scintillation POPOP were determined by examination of their compositions. Based on the research result obtained, composition of scintillator which had the highest efficiency. consists of P-Xylene solvent. primary scintillation PPO (5 g/l ) and secondary scintillation POPOP (0.5 g/l)

  2. Characterization of the PILATUS photon-counting pixel detector for X-ray energies from 1.75 keV to 60 keV

    International Nuclear Information System (INIS)

    Donath, T; Brandstetter, S; Commichau, S; Hofer, P; Lüthi, B; Schneebeli, M; Schulze-Briese, C; Cibik, L; Krumrey, M; Marggraf, S; Müller, P; Wernecke, J

    2013-01-01

    The PILATUS detector module was characterized in the PTB laboratory at BESSY II comparing modules with 320 μm thick and newly developed 450 μm and 1000 μm thick silicon sensors. Measurements were carried out over a wide energy range, in-vacuum from 1.75 keV to 8.8 keV and in air from 8 keV to 60 keV. The quantum efficiency (QE) was measured as a function of energy and the spatial resolution was measured at several photon energies both in terms of the modulation transfer function (MTF) from edge profile measurements and by directly measuring the point spread function (PSF) of a single pixel in a raster scan with a pinhole beam. Independent of the sensor thickness, the measured MTF and PSF come close to those for an ideal pixel detector with the pixel size of the PILATUS detector (172 × 172 μm 2 ). The measured QE follows the values predicted by calculation. Thicker sensors significantly enhance the QE of the PILATUS detectors for energies above 10 keV without impairing the spatial resolution and noise-free detection. In-vacuum operation of the PILATUS detector is possible at energies as low as 1.75 keV.

  3. Characterization of the PILATUS photon-counting pixel detector for X-ray energies from 1.75 keV to 60 keV

    Science.gov (United States)

    Donath, T.; Brandstetter, S.; Cibik, L.; Commichau, S.; Hofer, P.; Krumrey, M.; Lüthi, B.; Marggraf, S.; Müller, P.; Schneebeli, M.; Schulze-Briese, C.; Wernecke, J.

    2013-03-01

    The PILATUS detector module was characterized in the PTB laboratory at BESSY II comparing modules with 320 μm thick and newly developed 450 μm and 1000 μm thick silicon sensors. Measurements were carried out over a wide energy range, in-vacuum from 1.75 keV to 8.8 keV and in air from 8 keV to 60 keV. The quantum efficiency (QE) was measured as a function of energy and the spatial resolution was measured at several photon energies both in terms of the modulation transfer function (MTF) from edge profile measurements and by directly measuring the point spread function (PSF) of a single pixel in a raster scan with a pinhole beam. Independent of the sensor thickness, the measured MTF and PSF come close to those for an ideal pixel detector with the pixel size of the PILATUS detector (172 × 172 μm2). The measured QE follows the values predicted by calculation. Thicker sensors significantly enhance the QE of the PILATUS detectors for energies above 10 keV without impairing the spatial resolution and noise-free detection. In-vacuum operation of the PILATUS detector is possible at energies as low as 1.75 keV.

  4. Design and Prototyping of a High Granularity Scintillator Calorimeter

    International Nuclear Information System (INIS)

    Zutshi, Vishnu

    2016-01-01

    A novel approach for constructing fine-granularity scintillator calorimeters, based on the concept of an Integrated Readout Layer (IRL) was developed. The IRL consists of a printed circuit board inside the detector which supports the directly-coupled scintillator tiles, connects to the surface-mount SiPMs and carries the necessary front-end electronics and signal/bias traces. Prototype IRLs using this concept were designed, prototyped and successfully exposed to test beams. Concepts and implementations of an IRL carried out with funds associated with this contract promise to result in the next generation of scintillator calorimeters.

  5. Ionization and scintillation of nuclear recoils in gaseous xenon

    Energy Technology Data Exchange (ETDEWEB)

    Renner, J., E-mail: jrenner@lbl.gov [Lawrence Berkeley National Laboratory (LBNL), 1 Cyclotron Road, Berkeley, CA 94720 (United States); Department of Physics, University of California, Berkeley, CA 94720 (United States); Gehman, V.M.; Goldschmidt, A.; Matis, H.S.; Miller, T.; Nakajima, Y.; Nygren, D.; Oliveira, C.A.B.; Shuman, D. [Lawrence Berkeley National Laboratory (LBNL), 1 Cyclotron Road, Berkeley, CA 94720 (United States); Álvarez, V. [Instituto de Física Corpuscular (IFIC), CSIC & Universitat de València, Calle Catedrático José Beltrán, 2, 46980 Paterna, Valencia (Spain); Borges, F.I.G. [Departamento de Fisica, Universidade de Coimbra, Rua Larga, 3004-516 Coimbra (Portugal); Cárcel, S. [Instituto de Física Corpuscular (IFIC), CSIC & Universitat de València, Calle Catedrático José Beltrán, 2, 46980 Paterna, Valencia (Spain); Castel, J.; Cebrián, S. [Laboratorio de Física Nuclear y Astropartículas, Universidad de Zaragoza, Calle Pedro Cerbuna 12, 50009 Zaragoza (Spain); Cervera, A. [Instituto de Física Corpuscular (IFIC), CSIC & Universitat de València, Calle Catedrático José Beltrán, 2, 46980 Paterna, Valencia (Spain); Conde, C.A.N. [Departamento de Fisica, Universidade de Coimbra, Rua Larga, 3004-516 Coimbra (Portugal); and others

    2015-09-01

    Ionization and scintillation produced by nuclear recoils in gaseous xenon at approximately 14 bar have been simultaneously observed in an electroluminescent time projection chamber. Neutrons from radioisotope α-Be neutron sources were used to induce xenon nuclear recoils, and the observed recoil spectra were compared to a detailed Monte Carlo employing estimated ionization and scintillation yields for nuclear recoils. The ability to discriminate between electronic and nuclear recoils using the ratio of ionization to primary scintillation is demonstrated. These results encourage further investigation on the use of xenon in the gas phase as a detector medium in dark matter direct detection experiments.

  6. An integrated photosensor readout for gas proportional scintillation counters

    International Nuclear Information System (INIS)

    Lopes, J.A.M.; Santos, J.M.F. dos; Conde, C.A.N.

    1996-01-01

    A xenon gas proportional scintillation counter has been instrumented with a novel photosensor that replaces the photomultiplier tube normally used to detect the VUV secondary scintillation light. In this implementation, the collection grid of a planar gas proportional scintillation counter also functions as a multiwire proportional chamber to amplify and detect the photoelectrons emitted by a reflective CsI photocathode in direct contact with the xenon gas. This integrated concept combines greater simplicity, compactness, and ruggedness (no optical window is used) with low power consumption. An energy resolution of 12% was obtained for 59.6 keV x-rays

  7. Design and Prototyping of a High Granularity Scintillator Calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Zutshi, Vishnu [Northern Illinois Univ., DeKalb, IL (United States). Dept. of Physics

    2016-03-27

    A novel approach for constructing fine-granularity scintillator calorimeters, based on the concept of an Integrated Readout Layer (IRL) was developed. The IRL consists of a printed circuit board inside the detector which supports the directly-coupled scintillator tiles, connects to the surface-mount SiPMs and carries the necessary front-end electronics and signal/bias traces. Prototype IRLs using this concept were designed, prototyped and successfully exposed to test beams. Concepts and implementations of an IRL carried out with funds associated with this contract promise to result in the next generation of scintillator calorimeters.

  8. Alpha scintillation radon counting

    International Nuclear Information System (INIS)

    Lucas, H.F. Jr.

    1977-01-01

    Radon counting chambers which utilize the alpha-scintillation properties of silver activated zinc sulfide are simple to construct, have a high efficiency, and, with proper design, may be relatively insensitive to variations in the pressure or purity of the counter filling. Chambers which were constructed from glass, metal, or plastic in a wide variety of shapes and sizes were evaluated for the accuracy and the precision of the radon counting. The principles affecting the alpha-scintillation radon counting chamber design and an analytic system suitable for a large scale study of the 222 Rn and 226 Ra content of either air or other environmental samples are described. Particular note is taken of those factors which affect the accuracy and the precision of the method for monitoring radioactivity around uranium mines

  9. Scintillator detector array

    International Nuclear Information System (INIS)

    Cusano, D.A.; Dibianca, F.A.

    1981-01-01

    This patent application relates to a scintillator detector array for use in computerized tomography and comprises a housing including a plurality of chambers, the said housing having a front wall transmissive to x-rays and side walls opaque to x-rays, such as of tungsten and tantalum, a liquid scintillation medium including a soluble fluor, the solvent for the fluor being disposed in the chambers. The solvent comprises either an intrinsically high Z solvent or a solvent which has dissolved therein a high Z compound e.g. iodo or bromonaphthalene; or toluene, xylene or trimethylbenzene with a lead or tin alkyl dissolved therein. Also disposed about the chambers are a plurality of photoelectric devices. (author)

  10. DETECTORS: scintillating fibres

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    In the continual search for improved detection techniques, new materials are continually proving profitable. A good example is scintillating plastic fibres - tiny transparent threads sometimes finer than a human hair which transmit light. The narrowness and flexibility of these fibres was a major breakthrough for endoscopy - non-invasive techniques for viewing the otherwise inaccessible in surgery or machine inspection. In a more sophisticated form, these fibres find ready application in communications technology, where the goal is to transmit information rather than electrical power, replacing conventional and unwieldy current-carrying wire conductors. In particle physics, fibres have long been used to take the tiny scintillations produced when high energy particles hit fluorescent materials and 'conduct' them to photosensitive detectors some distance away

  11. A gamma scintillation spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Symbalisty, S

    1952-07-01

    A scintillation type gamma ray spectrometer employing coincidence counting, designed and built at the Physics Department of the University of Western Ontario is described. The spectrometer is composed of two anthracene and photomultiplier radiation detectors, two pulse analyzing channels, a coincidence stage, three scalers and a high voltage stabilized supply. A preliminary experiment to test the operation of the spectrometer was performed and the results of this test are presented. (author)

  12. Semiconductor high-energy radiation scintillation detector

    International Nuclear Information System (INIS)

    Kastalsky, A.; Luryi, S.; Spivak, B.

    2006-01-01

    We propose a new scintillation-type detector in which high-energy radiation generates electron-hole pairs in a direct-gap semiconductor material that subsequently recombine producing infrared light to be registered by a photo-detector. The key issue is how to make the semiconductor essentially transparent to its own infrared light, so that photons generated deep inside the semiconductor could reach its surface without tangible attenuation. We discuss two ways to accomplish this, one based on doping the semiconductor with shallow impurities of one polarity type, preferably donors, the other by heterostructure bandgap engineering. The proposed semiconductor scintillator combines the best properties of currently existing radiation detectors and can be used for both simple radiation monitoring, like a Geiger counter, and for high-resolution spectrography of the high-energy radiation. An important advantage of the proposed detector is its fast response time, about 1 ns, essentially limited only by the recombination time of minority carriers. Notably, the fast response comes without any degradation in brightness. When the scintillator is implemented in a qualified semiconductor material (such as InP or GaAs), the photo-detector and associated circuits can be epitaxially integrated on the scintillator slab and the structure can be stacked-up to achieve virtually any desired absorption capability

  13. Development of NaI(Tl) scintillating films for imaging soft x-rays

    International Nuclear Information System (INIS)

    Shepherd, J.A.

    1993-01-01

    Thin film NaI(Tl) scintillators, of areas of up to 130 cm 2 , have been fabricated and characterized for use on soft x-ray imaging photomultiplier tubes. Relevant parameters of photon-counting imaging detectors are defined and used to predict the performance of several materials, including CsI(Na), CsI(Tl), CaF 2 (Eu), Lu 2 (SiO 4 )O:Ce, and NaI(Tl), as thin film scintillators on fiber optic substrates. Also, x-ray imaging methodologies are compared. The NaI(Tl) films were vapor-deposited onto quartz and fiber optic substrates using a powder flash deposition technique. When compared to single crystal NaI(Tl), the films were found to have equally high light yield but lower energy resolution. Light yield optimization was studied in detail including the effects of substrate temperature, activator concentration in the evaporant, and boat temperature. Spatial resolution as well as parallax errors are discussed and measured for film thicknesses up to 61 μm. A technique is described that can substantially increase the light collection of high index films on fiber optic disks. The light collection was improved by 20% by coating the disk with potassium silicate before the NaI(Tl) deposition. Large area films, up to 130 cm 2 , had a spatial uniformity of response within ±1.5% for count rate and ±3.5% for light yield, and their spatial resolution exceeded 16.6 lp mm -1 when deposited onto fiber optic substrates. The 8-keV x-ray detection efficiency of the microchannel plate imaging photomultiplier tube coupled to a NaI(Tl) film scintillator is predicted to be 88%. Other uses for the films are also described

  14. Sub-aquatic response of a scintillator, fibre optic and silicon photomultiplier based radiation sensor

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Sarah F., E-mail: s.f.jackson@lancaster.ac.uk [Engineering Department, Lancaster University, Lancaster (United Kingdom); Monk, Stephen D., E-mail: s.monk@lancaster.ac.uk [Engineering Department, Lancaster University, Lancaster (United Kingdom); Stanley, Steven J., E-mail: steven.j.stanley@nnl.co.uk [National Nuclear Laboratory, A709 Springfields, Preston (United Kingdom); Lennox, Kathryn, E-mail: kathryn.lennox@nnl.co.uk [National Nuclear Laboratory, A709 Springfields, Preston (United Kingdom)

    2014-07-01

    We describe an attempt at the utilisation of two low level light sensors to improve on the design of a dose monitoring system, specifically for underwater applications with consideration for the effects of water attenuation. The gamma radiation ‘RadLine{sup ®}’ detector consists of an inorganic scintillating crystal coupled to a fibre optic cable which transports scintillation photons, up to hundreds of metres, to an optical sensor. Analysed here are two contemporary technologies; SensL's MiniSL a silicon photomultiplier (SiPM) and a Sens-Tech photon counting photomultiplier tube (PMT). A clinical radiotherapy linear accelerator (linac) is implemented as test beam, subjecting the RadLine{sup ®} to a highly controlled dose rate (ranging from 0 Sv h{sup −1} to 320 Sv h{sup −1}), averaging at 2 MeV in energy. The RadLine's underwater dose monitoring capabilities are tested with the aid of epoxy resin ‘solid water’ phantom blocks, used as a substitute for water. Our results show that the MiniSL SiPM is unsuitable for this application due to extremely high background noise levels, however the Sens-Tech PMT performs satisfactorily and the detected dose rate due to the effects of water attenuation compares strongly with MCNP simulation data and NIST database values. We conclude that the PMT shows promise for its ultimate use in the First Generation Magnox Storage Pond (FGMSP) on the Sellafield site. - Highlights: • RadLine{sup ®} consists of a scintillating crystal coupled to a fibre optic cable and photon detector. • Here the dose monitoring system is trialled with SiPM and PMT type photon detectors. • A clinical linear accelerator (linac) is used as a test beam. • Sub-aquatic response is compared to Monte Carlo simulations and the NIST database.

  15. Study of the correlation of scintillation decay and emission wavelength

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Yamaji, Akihiro; Kawaguchi, Noriaki; Kamada, Kei; Totsuka, Daisuke; Fukuda, Kentaro; Yamanoi, Kohei; Nishi, Ryosuke; Kurosawa, Shunsuke; Shimizu, Toshihiko; Sarukura, Nobuhiko

    2013-01-01

    In photoluminescence which directly excites the emission center of phosphor material is known to have a correlation between the emission wavelength and the decay time based on quantum mechanics. In scintillation phenomenon, host lattice of the material is first excited by ionizing radiation and then the excitation energy is transferred to emission centers. For the first time, we investigated the correlation between the scintillation decay and the emission wavelength by using pulse X-ray equipped streak camera system which could observe time and wavelength resolved scintillation phenomenon. Investigated materials were Ce 3+ , Pr 3+ and Nd 3+ doped oxides and fluorides which all showed 5d-4f transition based emission. As a result, we obtained the relation that τ (scintillation decay time) was proportional to the λ 2.15 (emission wavelength). -- Highlights: ► The correlation between emission wavelength and scintillation decay time is investigated. ► Photoluminescence decay times are also evaluated and compared with scintillation decay times. ► It is proved the relaxation process in emission center is dominant even in scintillation decay

  16. Liquid scintillation counting of chlorophyll

    International Nuclear Information System (INIS)

    Fric, F.; Horickova, B.; Haspel-Horvatovic, E.

    1975-01-01

    A precise and reproducible method of liquid scintillation counting was worked out for measuring the radioactivity of 14 C-labelled chlorophyll a and chlorophyll b solutions without previous bleaching. The spurious count rate caused by luminescence of the scintillant-chlorophyll system is eliminated by using a suitable scintillant and by measuring the radioactivity at 4 to 8 0 C after an appropriate time of dark adaptation. Bleaching of the chlorophyll solutions is necessary only for measuring of very low radioactivity. (author)

  17. Scintillating Optical Fiber Imagers for biology

    International Nuclear Information System (INIS)

    Mastrippolito, R.

    1990-01-01

    S.O.F.I (Scintillating Optical Fiber Imager) is a detector developed to replace the autoradiographic films used in molecular biology for the location of radiolabelled ( 32 P) DNA molecules in blotting experiments. It analyses samples on a 25 x 25 cm 2 square area still 25 times faster than autoradiographic films, with a 1.75 and 3 mm resolution for two orthogonal directions. This device performs numerised images with a dynamic upper than 100 which allows the direct quantitation of the analysed samples. First, this thesis describes the S.O.F.I. development (Scintillating Optical Fibers, coding of these fibers and specific electronic for the treatment of the Multi-Anode Photo-Multiplier signals) and experiments made in collaboration with molecular biology laboratories. In a second place, we prove the feasibility of an automatic DNA sequencer issued from S.O.F.I [fr

  18. Impact of anti-charge sharing on the zero-frequency detective quantum efficiency of CdTe-based photon counting detector system: cascaded systems analysis and experimental validation

    Science.gov (United States)

    Ji, Xu; Zhang, Ran; Chen, Guang-Hong; Li, Ke

    2018-05-01

    Inter-pixel communication and anti-charge sharing (ACS) technologies have been introduced to photon counting detector (PCD) systems to address the undesirable charge sharing problem. In addition to improving the energy resolution of PCD, ACS may also influence other aspects of PCD performance such as detector multiplicity (i.e. the number of pixels triggered by each interacted photon) and detective quantum efficiency (DQE). In this work, a theoretical model was developed to address how ACS impacts the multiplicity and zero-frequency DQE [DQE(0)] of PCD systems. The work focused on cadmium telluride (CdTe)-based PCD that often involves the generation and transport of K-fluorescence photons. Under the parallel cascaded systems analysis framework, the theory takes both photoelectric and scattering effects into account, and it also considers both the reabsorption and escape of photons. In a new theoretical treatment of ACS, it was considered as a modified version of the conventional single pixel (i.e. non-ACS) mode, but with reduced charge spreading distance and K-fluorescence travel distance. The proposed theoretical model does not require prior knowledge of the detailed ACS implementation method for each specific PCD, and its parameters can be experimentally determined using a radioisotope without invoking any Monte-Carlo simulation. After determining the model parameters, independent validation experiments were performed using a diagnostic x-ray tube and four different polychromatic beams (from 50 to 120 kVp). Both the theoretical and experimental results demonstrate that ACS increased the first and second moments of multiplicity for a majority of the x-ray energy and threshold levels tested, except when the threshold level was much lower than the x-ray energy level. However, ACS always improved DQE(0) at all energy and threshold levels tested.

  19. Neutron crosstalk between liquid scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Verbeke, J.M., E-mail: verbeke2@llnl.gov; Prasad, M.K., E-mail: prasad1@llnl.gov; Snyderman, N.J., E-mail: snyderman1@llnl.gov

    2015-09-11

    A method is proposed to quantify the fractions of neutrons scattering between liquid scintillators. Using a spontaneous fission source, this method can be utilized to quickly characterize an array of liquid scintillators in terms of crosstalk. The point model theory due to Feynman is corrected to account for these multiple scatterings. Using spectral information measured by the liquid scintillators, fractions of multiple scattering can be estimated, and mass reconstruction of fissile materials under investigation can be improved. Monte Carlo simulations of mono-energetic neutron sources were performed to estimate neutron crosstalk. A californium source in an array of liquid scintillators was modeled to illustrate the improvement of the mass reconstruction.

  20. Neutron crosstalk between liquid scintillators

    International Nuclear Information System (INIS)

    Verbeke, J.M.; Prasad, M.K.; Snyderman, N.J.

    2015-01-01

    A method is proposed to quantify the fractions of neutrons scattering between liquid scintillators. Using a spontaneous fission source, this method can be utilized to quickly characterize an array of liquid scintillators in terms of crosstalk. The point model theory due to Feynman is corrected to account for these multiple scatterings. Using spectral information measured by the liquid scintillators, fractions of multiple scattering can be estimated, and mass reconstruction of fissile materials under investigation can be improved. Monte Carlo simulations of mono-energetic neutron sources were performed to estimate neutron crosstalk. A californium source in an array of liquid scintillators was modeled to illustrate the improvement of the mass reconstruction

  1. Characterization of a fiber-taper charge-coupled device system for plastic scintillation dosimetry and comparison with the traditional lens system

    International Nuclear Information System (INIS)

    Gagnon, Louis-Philippe; Beddar, Sam; Beaulieu, Luc

    2015-01-01

    Purpose: To compare the signal-to-noise ratio (SNR), dose sensitivity and stability, and reproducibility of a lens-less charge-coupled device (CCD) photon-counting system with those of a traditional CCD + lens photon-counting system for plastic scintillation detectors (PSDs). Methods: The PSD used in this study was made from a 1-mm diameter, 2-mm long BCF60 scintillating fiber (emission peak at 530 nm) coupled to a 2.6-m Eska GH-4001 clear plastic fiber. This PSD was coupled to either a fiber-taper-based photon-counting system (FTS) or a lens-based photon-counting system (LS). In the FTS, the fiber-taper was attached to a 2048 × 2048 pixel, uncooled Alta 4020 polychromatic CCD camera. The LS consisted of a 1600 × 1200 pixel Alta 2020 polychromatic CCD camera (cooled to −18 °C) with a 50-mm lens with f/# = 1. Dose measurements were made under the same conditions for each system (isocentric setup; depth of 1.5 cm in solid water using a 10 × 10 cm 2 field size and 6-MV photon beam). The performance of each system was determined and compared, using the chromatic Čerenkov removal method to account for the stem effects produced in the clear plastic fiber. Results: The FTS increased the light collected by a factor of 4 compared with the LS, for the same dose measurements. This gain was possible because the FTS was not limited by the optical aberration that comes with a lens system. Despite a 45 °C operating temperature difference between the systems, the SNR was 1.8–1.9 times higher in the FTS than in the LS, for blue and green channels respectively. Low-dose measurements of 1.0 and 0.5 cGy were obtained with an accuracy of 3.4% and 5.6%, respectively, in the FTS, compared with 5.8% and 15.9% in the LS. The FTS provided excellent dose measurement stability as a function of integration time, with at most a 1% difference at 5 cGy. Under the same conditions, the LS system produced a measurement difference between 2 and 3%. Conclusion: Our results showed that

  2. Scintillating-fibre calorimetry

    International Nuclear Information System (INIS)

    Livan, M.; Vercesi, V.; Wigmans, R.

    1995-01-01

    In the past decade, calorimetry based on scintillating plastic fibres as active elements was developed from a conceptual idea to a mature detector technology, which is nowadays widely applied in particle physics experiments. This development and the performance characteristics of representative calorimeters, both for the detection of electromagnetic and hadronic showers, are reviewed. We also discuss new information on shower development processes in dense matter and its application to calorimetric principles that has emerged from some very thorough studies that were performed in the framework of this development. (orig.)

  3. Hybrid scintillators for neutron discrimination

    Science.gov (United States)

    Feng, Patrick L; Cordaro, Joseph G; Anstey, Mitchell R; Morales, Alfredo M

    2015-05-12

    A composition capable of producing a unique scintillation response to neutrons and gamma rays, comprising (i) at least one surfactant; (ii) a polar hydrogen-bonding solvent; and (iii) at least one luminophore. A method including combining at least one surfactant, a polar hydrogen-bonding solvent and at least one luminophore in a scintillation cell under vacuum or an inert atmosphere.

  4. Liquid scintillation in medical diagnosis

    International Nuclear Information System (INIS)

    Painter, K.

    1976-01-01

    With the tremendous increase in the application of radioassay, particularly radioimmunoassay, in the clinical laboratory liquid scintillation counting became an indispensable tool in diagnostic medicine. Few publications, however, have concerned themselves with problem areas which occur with the method in the clinical laboratory. The purpose of this presentation is to summarize our experiences with the liquid scintillation technique in the clinical situation

  5. A user's guide to scintillation

    International Nuclear Information System (INIS)

    Hewish, A.

    1989-01-01

    During the past four decades scintillation methods have been used for remote-sensing distant plasmas and for providing high angular resolution in radioastronomy. This brief review illustrates some of the techniques employed and explains the underlying theory in simple physical terms; it is not intended to be a complete survey of all applications of scintillation. (author)

  6. Laser Beam Scintillation with Applications

    CERN Document Server

    Andrews, Larry C; Young, Cynthia

    2001-01-01

    Renewed interest in laser communication systems has sparked development of useful new analytic models. This book discusses optical scintillation and its impact on system performance in free-space optical communication and laser radar applications, with a detailed look at propagation phenomena and the role of scintillation on system behavior. Intended for practicing engineers, scientists, and students.

  7. Scintillation light transport and detection

    International Nuclear Information System (INIS)

    Gabriel, T.A.; Lillie, R.A.

    1986-08-01

    The MORSE neutron gamma-ray transport code has been modified to allow for the transport of scintillation light. This modified code is used to analyze the light collection characteristics of a large liquid scintillator module (18 x 18 x 350 cm 3 )

  8. Extruding plastic scintillator at Fermilab

    International Nuclear Information System (INIS)

    Pla-Dalmau, Anna; Bross, Alain D.; Rykalin, Viktor V.

    2003-01-01

    An understanding of the costs involved in the production of plastic scintillators and the development of a less expensive material have become necessary with the prospects of building very large plastic scintillation detectors. Several factors contribute to the high cost of plastic scintillating sheets, but the principal reason is the labor-intensive nature of the manufacturing process. In order to significantly lower the costs, the current casting procedures had to be abandoned. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. This concept was tested and high quality extruded plastic scintillator was produced. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. This paper will discuss the characteristics of extruded plastic scintillator and its raw materials, the different manufacturing techniques and the current R andD program at Fermilab

  9. Scintillation properties of GSO

    International Nuclear Information System (INIS)

    Melcher, C.L.; Schweitzer, J.S.; Utsu, T.; Akiyama, S.

    1990-01-01

    The timing properties of Gd 2 SiO 5 :Ce (GSO) single crystal scintillators have previously been evaluated for positron emission tomography applications. The measured time resolution, however, was worse than expected from calculations based on photoelectron yield and a 60 nanosecond exponential decay constant, leading us to further investigate GSO's basic properties. With a time-correlated-single-photon technique, the authors have found two decay components, one of 56 ns and one of 600 ns, the latter containing 10--15% of the total scintillation output. This may explain the difference between the experimental and theoretical time resolutions and confirms a previous hypothesis of a long decay component. In addition, the authors have found that each component's decay constant strongly depends on the cerium concentration. The primary component varies from ∼ 20 ns to ∼ 190 ns and the secondary component varies from ∼ 70 ns to ∼ 1200 ns as the cerium concentration is varied from 5.0 mol% to 0.1 mol%

  10. Development of High-Resolution Scintillator Systems

    International Nuclear Information System (INIS)

    Larry A. Franks; Warnick J. Kernan

    2007-01-01

    Mercuric iodide (HgI2) is a well known material for the direct detection of gamma-rays; however, the largest volume achievable is limited by the thickness of the detector which needs to be a small fraction of the average trapping length for electrons. We report results of using HgI2 crystals to fabricate photocells used in the readout of scintillators. The optical spectral response and efficiency of these photocells were measured and will be reported. Nuclear response from an HgI2 photocell that was optically matched to a cerium-activated scintillator is presented and discussed. Further improvements can be expected by optimizing the transparent contact technology

  11. Scintillating plate calorimeter optical design

    International Nuclear Information System (INIS)

    McNeil, R.; Fazely, A.; Gunasingha, R.; Imlay, R.; Lim, J.

    1990-01-01

    A major technical challenge facing the builder of a general purpose detector for the SSC is to achieve an optimum design for the calorimeter. Because of its fast response and good energy resolution, scintillating plate sampling calorimeters should be considered as a possible technology option. The work of the Scintillating Plate Calorimeter Collaboration is focused on compensating plate calorimeters. Based on experimental and simulation studies, it is expected that a sampling calorimeter with alternating layers of high-Z absorber (Pb, W, DU, etc.) and plastic scintillator can be made compensating (e/h = 1.00) by suitable choice of the ratio of absorber/scintillator thickness. Two conceptual designs have been pursued by this subsystem collaboration. One is based on lead as the absorber, with read/out of the scintillator plates via wavelength shifter fibers. The other design is based on depleted uranium as the absorber with wavelength shifter (WLS) plate readout. Progress on designs for the optical readout of a compensating scintillator plate calorimeter are presented. These designs include readout of the scintillator plates via wavelength shifter plates or fiber readout. Results from radiation damage studies of the optical components are presented

  12. Radiation damage studies on new liquid scintillators and liquid-core scintillating fibers

    International Nuclear Information System (INIS)

    Golovkin, S.V.

    1994-01-01

    The radiation resistant of some new liquid scintillation and capillaries filled with liquid scintillators has been presented. It was found that scintillation efficiency of the scintillator based on 1-methyl naphthalene with a new R39 only by 10% at the dose of 190 Mrad and the radiation resistance of thin liquid-core scintillating was decreased fibers exceeded 60 Mrad. 35 refs

  13. Scintillators and other particle optical detectors

    International Nuclear Information System (INIS)

    Chipaux, R.

    2011-01-01

    The author reports and comments his researcher career in the field of particle optical detectors. He addresses the cases of organic scintillators (scintillating fibers, liquid scintillators), inorganic scintillators (crystals for electromagnetic calorimetry, crystals for solar neutrino spectroscopy), and Cherenkov Effect detectors. He also reports his works on Cd Te detectors and their modelling

  14. Externally mounted radioactivity detector for MWD employing radial inline scintillator and photomultiplier tube

    International Nuclear Information System (INIS)

    Meisner, J.E.; Mumby, E.S.; Groeschel, V.E.

    1991-01-01

    Improved radioactivity well logging may be achieved by mounting a scintillator and photomultiplier tube in a single case interfacing with a hole extending through a drill collar at the lower end of a drill string so that measurements can be made while drilling. Radioactive sources (when required for well logging) are mounted in cavities which open to the exterior of the drill collar. Light from the scintillator is coupled directly to the aligned photomultiplier tube both of which are mounted in a case extending radially within the drill collar and sealingly engaging an electronics housing within the drill collar and the drill collar wall surrounding the hole. The scintillator is of greater diameter than the photomultiplier tube. A frustoconical light pipe connects the scintillator and the photomultiplier tube, channeling scintillation in the crystal to the photomultiplier to provide an amplified detection capability over that for a scintillator having the same diameter as the photomultiplier tube. (author)

  15. Experimental research of plastic scintillation detector loaded 6Li neutron energy response

    International Nuclear Information System (INIS)

    Wang Lizong; Zhang Chuanfei; Peng Taiping; Guo Cun; Yang Hongqiong; Zhang Jianhua

    2005-01-01

    A new plastic scintillator, plastic scintillator loaded 6 Li, is brought forward and developed in this paper in order to increase low energy neutron sensitivity. Neutron sensitivity of several plastic scintillation detectors loaded 6 Li new developed in neutron energy range 0.2 MeV-5.0 MeV are calibrated by direct current at serial accelerator. Energy response curves of the detectors are obtained in this experiment. It is shown that this new plastic scintillation detector can increase low energy neutron sensitivity in experimental results. (authors)

  16. Scintillation 1024-channel hodoscope

    International Nuclear Information System (INIS)

    Kotov, I.V.; Krasnokutskij, R.N.; Kurbakov, V.I.; Shchukin, A.V.

    1993-01-01

    Flow diagram of voltage divider for photomultiplier used in scintillation multichannel hodoscope is described. The suggested diagram of the divider allows to optimize potential distribution at the innput chamber (photocathode - modulator - first dynode) and in the tail segment of the divider (the nineth dynode-anode). Adjustment of high voltage is conducted using multirotational potentiometer switched in series with the divider. Amplifier-limiter with 80 mkA threshold set at voltage comparator is placed at divide plate. Threshold of its sensitivity constitutes 80 mkA. Hodoscope supply system consists of supply sources of comparators (+-6V) four sources of auxiliary supply sources of the last dynodes of photomultipliers and high-voltage source. Current consumption constitutes 25 A by - 6V, 23 A by + 6 V for the whole hodoscope and up to 200 mA from high-voltage source for one plane. Additional charging sources have constant consumption equal to ∼ 20 mA

  17. Encapsulated scintillation detector

    International Nuclear Information System (INIS)

    Toepke, I.L.

    1982-01-01

    A scintillation detector crystal is encapsulated in a hermetically sealed housing having a glass window. The window may be mounted in a ring by a compression seal formed during cooling of the ring and window after heating. The window may be chemically bonded to the ring with or without a compression seal. The ring is welded to the housing along thin weld flanges to reduce the amount of weld heat which must be applied. A thin section is provided to resist the flow of welding heat to the seal between the ring and the window thereby forming a thermal barrier. The thin section may be provided by a groove cut partially through the wall of the ring. A layer of PTFE between the tubular body and the crystal minimizes friction created by thermal expansion. Spring washers urge the crystal towards the window. (author)

  18. Scintillation counter, segmented shield

    International Nuclear Information System (INIS)

    Olson, R.E.; Thumim, A.D.

    1975-01-01

    A scintillation counter, particularly for counting gamma ray photons, includes a massive lead radiation shield surrounding a sample-receiving zone. The shield is disassembleable into a plurality of segments to allow facile installation and removal of a photomultiplier tube assembly, the segments being so constructed as to prevent straight-line access of external radiation through the shield into radiation-responsive areas. Provisions are made for accurately aligning the photomultiplier tube with respect to one or more sample-transmitting bores extending through the shield to the sample receiving zone. A sample elevator, used in transporting samples into the zone, is designed to provide a maximum gamma-receiving aspect to maximize the gamma detecting efficiency. (U.S.)

  19. Properties of scintillator solutes

    International Nuclear Information System (INIS)

    Fluornoy, J.M.

    1998-06-01

    This special report summarizes measurements of the spectroscopic and other properties of the solutes that were used in the preparation of several new liquid scintillators developed at EG and G/Energy Measurements/Santa Barbara Operations (the precursor to Bechtel Nevada/Special Technologies Laboratory) on the radiation-to-light converter program. The data on the individual compounds are presented in a form similar to that used by Prof. Isadore Berlman in his classic handbook of fluorescence spectra. The temporal properties and relative efficiencies of the new scintillators are presented in Table 1, and the efficiencies as a function of wavelength are presented graphically in Figure 1. In addition, there is a descriptive glossary of the abbreviations used herein. Figure 2 illustrates the basic structures of some of the compounds and of the four solvents reported in this summary. The emission spectra generally exhibit more structure than the absorption spectra, with the result that the peak emission wavelength for a given compound may lie several nm away from the wavelength, λ avg , at the geometric center of the emission spectrum. Therefore, the author has chosen to list absorption peaks, λ max , and emission λ avg values in Figures 3--30, as being most illustrative of the differences between the compounds. The compounds, BHTP, BTPB, ADBT, and DPTPB were all developed on this program. P-terphenyl, PBD, and TPB are commercially available blue emitters. C-480 and the other longer-wavelength emitters are laser dyes available commercially from Exciton Corporation. 1 ref., 30 figs

  20. Sub-nanosecond plastic scintillators

    International Nuclear Information System (INIS)

    Lyons, P.B.; Caldwell, S.E.; Hocker, L.P.; Crandall, D.G.; Zagarino, P.A.; Cheng, J.; Tirsell, G.; Hurlbut, C.R.

    1977-01-01

    Quenched plastic scintillators have been developed that yield much faster short decay components and greatly reduced long decay components compared to conventional plastic scintillators. The plastics are produced through the addition of selected quench agents to NE111 plastic scintillator that result in reduced total light output. Eight different agents have been studied. Benzophenone and piperidine are two of the most effective quench agents. Data are presented both for short and long decay components. The plastics are expected to make significant contributions in areas of plasma diagnostics

  1. Sub-nanosecond plastic scintillators

    International Nuclear Information System (INIS)

    Lyons, P.B.; Caldwell, S.E.; Hocker, L.P.; Crandall, D.G.; Zagarino, P.A.; Cheng, J.; Tirsell, G.; Hurlbut, C.R.

    1976-01-01

    Quenched plastic scintillators have been developed that yield much faster short decay components and greatly reduced long decay components compared to conventional plastic scintillators. The plastics are produced through the addition of selected quench agents to NE111 plastic scintillator that result in reduced total light output. Eight different agents have been studied. Benzophenone and piperidine are two of the most effective quench agents. Data are presented both for short and long decay components. The plastics are expected to make significant contributions in areas of plasma diagnostics

  2. Applications of liquid scintillation tubes

    International Nuclear Information System (INIS)

    Broga, D.W.

    1977-01-01

    A new cocktail containing device for liquid scintillation counting, the scintillation tube, consists of a two-layered plastic bag which is heatsealed after the cocktail and sample have been placed in it. It is then placed in a carrying vial and counted in a conventional liquid scintillation counter. These tubes have proved to be a practical and economical alternative to vials. Some of their advantages are elimination of absorption problems, transparency, lower background and higher counting efficiency, low breakage danger and savings in waste disposal costs. Two applications for which the tubes are particularly suitable are the counting of laboratory swipes and urine analysis. (author)

  3. Scintillation counter with MRS APD light readout

    International Nuclear Information System (INIS)

    Akindinov, A.; Bondarenko, G.; Golovin, V.; Grigoriev, E.; Grishuk, Yu.; Mal'kevich, D.; Martemiyanov, A.; Ryabinin, M.; Smirnitskiy, A.; Voloshin, K.

    2005-01-01

    START, a high-efficiency and low-noise scintillation detector for ionizing particles, was developed for the purpose of creating a high-granular system for triggering cosmic muons. Scintillation light in START is detected by MRS APDs (Avalanche Photo-Diodes with Metal-Resistance-Semiconductor Structure), operated in the Geiger mode, which have 1mm 2 sensitive areas. START is assembled from a 15x15x1cm 3 scintillating plastic plate, two MRS APDs and two pieces of wavelength-shifting optical fiber stacked in circular coils inside the plastic. The front-end electronic card is mounted directly on the detector. Tests with START have confirmed its operational consistency, over 99% efficiency of MIP registration and good homogeneity. START demonstrates a low intrinsic noise of about 10 -2 Hz. If these detectors are to be mass-produced, the cost of a mosaic array of STARTs is estimated at a moderate level of 2-3kUSD/m 2

  4. Calorimeter detector consisting of a KMgF3 scintillator and parallel-plate avalanche chamber

    International Nuclear Information System (INIS)

    Buzulutskov, A.F.; Turchanovich, L.K.; Vasil'chenko, V.G.

    1989-01-01

    Scintillations of a KMgF 3 crystal have been detected in the parallel-plate avalanche chamber with a TEA gaseous photocathode, the scintillation signal is shown to be much higher than the direct ionization one. The characteristic properties of the calorimeters on the basis of such structure with electrical and optical readout are discussed. 10 refs.; 4 figs

  5. Temperature dependence of plastic scintillators

    Science.gov (United States)

    Peralta, L.

    2018-03-01

    Plastic scintillator detectors have been studied as dosimeters, since they provide a cost-effective alternative to conventional ionization chambers. Several articles have reported undesired response dependencies on beam energy and temperature, which provides the motivation to determine appropriate correction factors. In this work, we studied the light yield temperature dependency of four plastic scintillators, BCF-10, BCF-60, BC-404, RP-200A and two clear fibers, BCF-98 and SK-80. Measurements were made using a 50 kVp X-ray beam to produce the scintillation and/or radioluminescence signal. The 0 to 40 °C temperature range was scanned for each scintillator, and temperature coefficients were obtained.

  6. Photon statistics in scintillation crystals

    Science.gov (United States)

    Bora, Vaibhav Joga Singh

    Scintillation based gamma-ray detectors are widely used in medical imaging, high-energy physics, astronomy and national security. Scintillation gamma-ray detectors are eld-tested, relatively inexpensive, and have good detection eciency. Semi-conductor detectors are gaining popularity because of their superior capability to resolve gamma-ray energies. However, they are relatively hard to manufacture and therefore, at this time, not available in as large formats and much more expensive than scintillation gamma-ray detectors. Scintillation gamma-ray detectors consist of: a scintillator, a material that emits optical (scintillation) photons when it interacts with ionization radiation, and an optical detector that detects the emitted scintillation photons and converts them into an electrical signal. Compared to semiconductor gamma-ray detectors, scintillation gamma-ray detectors have relatively poor capability to resolve gamma-ray energies. This is in large part attributed to the "statistical limit" on the number of scintillation photons. The origin of this statistical limit is the assumption that scintillation photons are either Poisson distributed or super-Poisson distributed. This statistical limit is often dened by the Fano factor. The Fano factor of an integer-valued random process is dened as the ratio of its variance to its mean. Therefore, a Poisson process has a Fano factor of one. The classical theory of light limits the Fano factor of the number of photons to a value greater than or equal to one (Poisson case). However, the quantum theory of light allows for Fano factors to be less than one. We used two methods to look at the correlations between two detectors looking at same scintillation pulse to estimate the Fano factor of the scintillation photons. The relationship between the Fano factor and the correlation between the integral of the two signals detected was analytically derived, and the Fano factor was estimated using the measurements for SrI2:Eu, YAP

  7. Radiation Damage in Scintillating Crystals

    CERN Document Server

    Zhu Ren Yuan

    1998-01-01

    Crystal Calorimetry in future high energy physics experiments faces a new challenge to maintain its precision in a hostile radiation environment. This paper discusses the effects of radiation damage in scintillating crystals, and concludes that the predominant radiation damage effect in crystal scintillators is the radiation induced absorption, or color center formation, not the loss of the scintillation light yield. The importance of maintaining crystal's light response uniformity and the feasibility to build a precision crystal calorimeter under radiation are elaborated. The mechanism of the radiation damage in scintillating crystals is also discussed. While the damage in alkali halides is found to be caused by the oxygen or hydroxyl contamination, it is the structure defects, such as oxygen vacancies, cause damage in oxides. Material analysis methods used to reach these conclusions are presented in details.

  8. Alkali metal hafnium oxide scintillators

    Science.gov (United States)

    Bourret-Courchesne, Edith; Derenzo, Stephen E.; Taylor, Scott Edward

    2018-05-08

    The present invention provides for a composition comprising an inorganic scintillator comprising an alkali metal hafnate, optionally cerium-doped, having the formula A2HfO3:Ce; wherein A is an alkali metal having a valence of 1, such as Li or Na; and the molar percent of cerium is 0% to 100%. The alkali metal hafnate are scintillators and produce a bright luminescence upon irradiation by a suitable radiation.

  9. Performance study of Philips digital silicon photomultiplier coupled to scintillating crystals

    International Nuclear Information System (INIS)

    Liu, Z.; Pizzichemi, M.; Paganoni, M.; Auffray, E.; Lecoq, P.

    2016-01-01

    Silicon photomultipliers (SiPMs) and scintillators are often arranged in the shape of arrays in Positron Emission Tomography (PET) systems. Digital SiPMs provide signal readout in single photon avalanche diode (SPAD) level. From the photon count rate measurement of each SPAD cell of digital SiPM, we found that the output scintillating photons distribute in an area larger than the scintillator physical coupling area. Taking advantage of the possibility to enable/disable individual cells of the digital SiPM, a group of Lutetium-yttrium oxyorthosilicate (LYSO) crystals with different dimensions coupled to a digital SiPM was used to study the influence of using different SiPM active area on the number of photons detected, energy resolution and coincidence time resolution (CTR). For the same crystal coupled to the digital SiPM, the larger the active area of digital SiPM, the higher the number of photons detected. The larger active area of the digital SiPM also results in a better energy resolution after saturation correction. The best energy resolution full width half maximum (FWHM) obtained for the 2×2×5mm 3 , 2×2×10 mm 3 , 2×2×15mm 3 , 2×2×20mm 3 LYSO crystals was 10.7%, 11.6%, 12.1%, 12.5%, respectively. For crystals with different cross sections coupled to the digital SiPM, we found that the larger the cross section of coupling area, the more photons were detected and thus a better energy resolution was obtained. The CTR of crystals fully wrapped with Teflon or without wrapping was measured by positioning two identical crystals facing each other. A larger area of digital SiPM improves the CTR and the CTR reaches the plateau when the active area is larger than 2.2×2.2mm 2 with both two configurations of wrapping. The best CTR value for the 2×2×5mm 3 , 2×2×10mm 3 , 2×2×15mm 3 , 2×2×20mm 3 LYSO crystals was 128.9 ps, 148.4 ps, 171.6 ps, 177.9 ps, respectively. The measurements performed lead us to conclude that optimising the coupling between crystal

  10. Ionospheric Scintillation Effects on GPS

    Science.gov (United States)

    Steenburgh, R. A.; Smithtro, C.; Groves, K.

    2007-12-01

    . Ionospheric scintillation of Global Positioning System (GPS) signals threatens navigation and military operations by degrading performance or making GPS unavailable. Scintillation is particularly active, although not limited to, a belt encircling the earth within 20 degrees of the geomagnetic equator. As GPS applications and users increases, so does the potential for detrimental impacts from scintillation. We examined amplitude scintillation data spanning seven years from Ascension Island, U.K.; Ancon, Peru; and Antofagasta, Chile in the Atlantic/Americas longitudinal sector at as well as data from Parepare, Indonesia; Marak Parak, Malaysia; Pontianak, Indonesia; Guam; and Diego Garcia, U.K.; in the Pacific longitudinal sector. From these data, we calculate percent probability of occurrence of scintillation at various intensities described by the S4 index. Additionally, we determine Dilution of Precision at one minute resolution. We examine diurnal, seasonal and solar cycle characteristics and make spatial comparisons. In general, activity was greatest during the equinoxes and solar maximum, although scintillation at Antofagasta, Chile was higher during 1998 rather than at solar maximum.

  11. Irregular ionization and scintillation of the ionosphere in equator region

    International Nuclear Information System (INIS)

    Shinno, Kenji

    1974-01-01

    The latest studies on the scintillation in satellite communication and its related irregularities of ionosphere are reviewed. They were made clear by means of spread-F, the direct measurement with scientific satellites, VHF radar observation, and radio wave propagation in equator region. The fundamental occurrence mechanism may be instability of plasma caused by the interaction of movement of neutral atmosphere and magnetic field. Comparison of the main characteristics of scintillation, namely the dependence on region, solar activity, season, local time, geomagnetic activity, movement in ionosphere, scattering source, frequency and transmission mode, was made and the correlation among spread-F, TEP and scintillation was summarized. The latest principal studies were the observations made by Intelsat and by ATS. Scintillation of Syncom-3 and Intelsat-II-F2 and spread-F by ionosphere observation were compared by Huang. It is reasonable to consider that the occurrence of scintillation is caused by the irregularities in ionosphere which are particular in equator region, because of the similar characteristics of spread-F and VHF propagation in the equator region. These three phenomena may occur in relation to the irregularities of ionosphere. Interpretation of spread-F and the abnormal propagation wave across the equator are given. The study using VHF radar and the movement of irregular ionization by the direct observation with artificial satellites are reviewd. (Iwakiri, K.)

  12. Influence of SrF_2-doping in AlN ceramics on scintillation and dosimeter properties

    International Nuclear Information System (INIS)

    Kojima, Kaori; Okada, Go; Fukuda, Kentaro; Yanagida, Takayuki

    2016-01-01

    In this study, we synthesized undoped AlN and SrF_2-doped AlN (AlN-SrF_2) ceramics by Spark Plasma Sintering (SPS), and we characterized their optical, scintillation and dosimeter properties. The prepared undoped AlN ceramic had gray color and visually non-transparent whereas, with an addition of SrF_2, the transparency improved and became translucent. The measured in-line transmittance was approximately 0.2% at wavelengths longer than 500 nm. While the addition of SrF_2 decreased the scintillation intensity, the decay time was significantly fastened, which is a great advantage for fast photon counting-based measurements. Both the thermally-stimulated luminescence (TSL) and optically-stimulated luminescence (OSL) showed good linear response from the milli-gray range to over 10 Gy. The sensitivity seems to decrease by an addition of SrF_2 as it suppresses structural defect centers which are responsible for dosimeter properties. However, the main TSL glow peak position shifts to higher temperature with the addition of SrF_2, which indicates that inclusion of SrF_2 improves the TSL signal stability. - Highlights: • We synthesized undoped and SrF_2-doped AlN ceramics by Spark Plasma Sintering. • We evaluated scintillator and dosimeter properties of undoped and SrF_2-doped AlN. • By doping with SrF_2, the decay time is shortened. • By doping with SrF_2, the stability of TSL and OSL is improved.

  13. Scintillation counter based radiation dosimeter

    International Nuclear Information System (INIS)

    Shin, Jeong Hyun

    2009-02-01

    The average human exposure per year is about 240mrem which is come from Radon and human body and terrestrial and cosmic radiation and man-made source. Specially radiation exposure through air from environmental radiation sources is 80mrem/yr(= 0.01mR/hr) which come from Terrestrial and cosmic radiation. Radiation dose is defined as energy deposit/mass. There are two major methods to detect radiation. First method is the energy integration using Air equivalent material like GM counter wall material. Second method is the spectrum to dose conversion method using NaI(Tl), HPGe. These two methods are using generally to detect radiation. But these methods are expensive. So we need new radiation detection method. The research purpose is the development of economical environmental radiation dosimeter. This system consists of Plastic/Inorganic scintillator and Si photo-diode based detector and counting based circuitry. So count rate(cps) can be convert to air exposure rate(R/hr). There are three major advantages in this system. First advantages is no high voltage power supply like GM counter. Second advantage is simple electronics. Simple electronics system can be achieved by Air-equivalent scintillation detector with Al filter for the same detection efficiency vs E curve. From former two advantages, we can know the most important advantages of the this system. Third advantage is economical system. The price of typical GM counter is about $1000. But the price of our system is below $100 because of plastic scintillator and simple electronics. The role of scintillation material is emitting scintillation which is the flash of light produced in certain materials when they absorb ionizing radiation. Plastic scintillator is organic scintillator which is kind of hydrocarbons. The special point are cheap price, large size production(∼ton), moderate light output, fast light emission(ns). And the role of Al filter is equalizing counting efficiency of air and scintillator for

  14. Marine radioactivity measurements with liquid scintillation spectrometers

    International Nuclear Information System (INIS)

    Liong Wee Kwong, L.; Povinec, P.P.

    1999-01-01

    Liquid Scintillation Spectrometry (LSS) has now become the most widespread method for quantitative analytical measurement of low levels of β-emitting radionuclides like 3 H and 14 C. The high efficiency resulting from the latest development in LSS makes this technique not only appropriate but also enables direct measurement in environmental samples without excessive preparation. The introduction of several new cocktails based on solvents with a high flashpoint containing surfactants and having a high degree of aqueous sample compatibility has also contributed to the simplification of procedures

  15. Digital signal processing for a thermal neutron detector using ZnS(Ag):{sup 6}LiF scintillating layers read out with WLS fibers and SiPMs

    Energy Technology Data Exchange (ETDEWEB)

    Mosset, J.-B., E-mail: jean-baptiste.mosset@psi.ch; Stoykov, A.; Greuter, U.; Hildebrandt, M.; Schlumpf, N.

    2016-07-11

    We present a digital signal processing system based on a photon counting approach which we developed for a thermal neutron detector consisting of ZnS(Ag):{sup 6}LiF scintillating layers read out with WLS fibers and SiPMs. Three digital filters have been evaluated: a moving sum, a moving sum after differentiation and a digital CR-RC{sup 4} filter. The performances of the detector with these filters are presented. A full analog signal processing using a CR-RC{sup 4} filter has been emulated digitally. The detector performance obtained with this analog approach is compared with the one obtained with the best performing digital approach. - Highlights: • Application of digital signal processing for a SiPM-based ZnS:6LiF neutron detector. • Optimisation of detector performances with 3 different digital filters. • Comparison with detector performances with a full analog signal processing.

  16. Neutrons detection by scintillation; Detection de neutrons par scintillations

    Energy Technology Data Exchange (ETDEWEB)

    Giraudon, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-01-15

    The absence of charge of neutrons and their elevated penetration power make difficult their detection. Techniques vary otherwise with the energy of the particle. The author proposes the realization of a scintillation detector with a big volume of liquid scintillator and containing boron for the detection of slowing-down neutrons in the domain of intermediate energies from 1 to 10{sup 5} eV about. (M.B.) [French] L'absence de charge du neutron et son pouvoir de penetration eleve rendent difficile sa detection. Les techniques par ailleurs varient avec l'energie de cette particule. L'auteur propose la realisation d'un detecteur a scintillations comprenant un grand volume de scintillateur liquide et contenant du bore pour la detection des neutrons en ralentissement dans le domaine des energies intermediaires de 1 a 10{sup 5} eV environ. (M.B.)

  17. Cherenkov and scintillation light separation in organic liquid scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Caravaca, J.; Descamps, F.B.; Land, B.J.; Orebi Gann, G.D. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Yeh, M. [Brookhaven National Laboratory, Upton, NY (United States)

    2017-12-15

    The CHErenkov/Scintillation Separation experiment (CHESS) has been used to demonstrate the separation of Cherenkov and scintillation light in both linear alkylbenzene (LAB) and LAB with 2 g/L of PPO as a fluor (LAB/PPO). This is the first successful demonstration of Cherenkov light detection from the more challenging LAB/PPO cocktail and improves on previous results for LAB. A time resolution of 338 ± 12 ps FWHM results in an efficiency for identifying Cherenkov photons in LAB/PPO of 70 ± 3% and 63 ± 8% for time- and charge-based separation, respectively, with scintillation contamination of 36 ± 5% and 38 ± 4. LAB/PPO data is consistent with a rise time of τ{sub r} = 0.72 ± 0.33 ns. (orig.)

  18. Cherenkov and scintillation light separation in organic liquid scintillators

    International Nuclear Information System (INIS)

    Caravaca, J.; Descamps, F.B.; Land, B.J.; Orebi Gann, G.D.; Yeh, M.

    2017-01-01

    The CHErenkov/Scintillation Separation experiment (CHESS) has been used to demonstrate the separation of Cherenkov and scintillation light in both linear alkylbenzene (LAB) and LAB with 2 g/L of PPO as a fluor (LAB/PPO). This is the first successful demonstration of Cherenkov light detection from the more challenging LAB/PPO cocktail and improves on previous results for LAB. A time resolution of 338 ± 12 ps FWHM results in an efficiency for identifying Cherenkov photons in LAB/PPO of 70 ± 3% and 63 ± 8% for time- and charge-based separation, respectively, with scintillation contamination of 36 ± 5% and 38 ± 4. LAB/PPO data is consistent with a rise time of τ r = 0.72 ± 0.33 ns. (orig.)

  19. Neutrons detection by scintillation; Detection de neutrons par scintillations

    Energy Technology Data Exchange (ETDEWEB)

    Giraudon, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-01-15

    The absence of charge of neutrons and their elevated penetration power make difficult their detection. Techniques vary otherwise with the energy of the particle. The author proposes the realization of a scintillation detector with a big volume of liquid scintillator and containing boron for the detection of slowing-down neutrons in the domain of intermediate energies from 1 to 10{sup 5} eV about. (M.B.) [French] L'absence de charge du neutron et son pouvoir de penetration eleve rendent difficile sa detection. Les techniques par ailleurs varient avec l'energie de cette particule. L'auteur propose la realisation d'un detecteur a scintillations comprenant un grand volume de scintillateur liquide et contenant du bore pour la detection des neutrons en ralentissement dans le domaine des energies intermediaires de 1 a 10{sup 5} eV environ. (M.B.)

  20. Interstellar Scintillation and Scattering of Micro-arc-second AGN

    Directory of Open Access Journals (Sweden)

    David L. Jauncey

    2016-11-01

    Full Text Available The discovery of the first quasar 3C 273 led directly to the discovery of their variability at optical and radio wavelengths. We review the radio variability observations, in particular the variability found at frequencies below 1 GHz, as well as those exhibiting intra-day variability (IDV at cm wavelengths. Observations have shown that IDV arises principally from scintillation caused by scattering in the ionized interstellar medium of our Galaxy. The sensitivity of interstellar scintillation towards source angular sizes has provided a powerful tool for studying the most compact components of radio-loud AGN at microarcsecond and milliarcsecond scale resolution.

  1. Performance of a highly segmented scintillating fibres electromagnetic calorimeter

    International Nuclear Information System (INIS)

    Asmone, A.; Bertino, M.; Bini, C.; De Zorzi, G.; Diambrini Palazzi, G.; Di Cosimo, G.; Di Domenico, A.; Garufi, F.; Gauzzi, P.; Zanello, D.

    1993-01-01

    A prototype of scintillating fibres electromagnetic calorimeter has been constructed and tested with 2, 4 and 8 GeV electron beams at the CERN PS. The calorimeter modules consist of a Bi-Pb-Sn alloy and scintillating fibres. The fibres are parallel to the modules longer axis, and nearly parallel to the incident electrons direction. The calorimeter has two different segmentation regions of 24x24 mm 2 and 8x24 mm 2 cross area respectively. Results on energy and impact point space resolution are obtained and compared for the two different granularities. (orig.)

  2. Optical characteristics of the thin-film scintillator detector

    International Nuclear Information System (INIS)

    Muga, L.; Burnsed, D.

    1976-01-01

    A study of the thin-film detector (TFD) was made in which various light guide and scintillator film support configurations were tested for efficiency of light coupling. Masking of selected portions of the photomultiplier (PM) tube face revealed the extent to which emitted light was received at the exposed PM surfaces. By blocking off selected areas of the scintillator film surface from direct view of the PM tube faces, a measure of the light-guiding efficiency of the film and its support could be estimated. The picture that emerges is that, as the light which is initially trapped in the thin film spreads radially outward from the ion entrance/exit point, it is scattered out of the film by minute imperfections. Optimum signals were obtained by a configuration in which the thin scintillator film was supported on a thin rectangular Celluloid frame inserted within a highly polished metal cylindrical sleeve

  3. ATLAS Rewards Russian Supplier for Scintillating Tile Production

    CERN Multimedia

    2001-01-01

    At a ceremony held at CERN on 30 July, the ATLAS collaboration awarded Russian firm SIA Luch from Podolsk in the Moscow region an ATLAS Suppliers Award. This follows delivery by the company of the final batch of scintillating tiles for the collaboration's Tile Calorimeter some six months ahead of schedule.   Representatives of Russian firm Luch Podolsk received the ATLAS Suppliers Award in the collaboration's Tile Calorimeter instrumentation plant at CERN on 30 July. In front of one Tile Calorimeter module instrumented by scintillating tiles are (left to right) IHEP physicists Evgueni Startchenko and Andrei Karioukhine, Luch Podolsk representatives Igor Karetnikov and Yuri Zaitsev, Tile Calorimeter Project Leader Rupert Leitner, ATLAS spokesperson Peter Jenni, and CERN Tile Calorimeter group leader Ana Henriques-Correia. Scintillating tiles form the active part of the ATLAS hadronic Tile Calorimeter, which will measure the energy and direction of particles produced in LHC collisions. They are emb...

  4. Scintillation-Hardened GPS Receiver

    Science.gov (United States)

    Stephens, Donald R.

    2015-01-01

    CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

  5. Development of radiation hard scintillators

    International Nuclear Information System (INIS)

    Markley, F.; Woods, D.; Pla-Dalmau, A.; Foster, G.; Blackburn, R.

    1992-05-01

    Substantial improvements have been made in the radiation hardness of plastic scintillators. Cylinders of scintillating materials 2.2 cm in diameter and 1 cm thick have been exposed to 10 Mrads of gamma rays at a dose rate of 1 Mrad/h in a nitrogen atmosphere. One of the formulations tested showed an immediate decrease in pulse height of only 4% and has remained stable for 12 days while annealing in air. By comparison a commercial PVT scintillator showed an immediate decrease of 58% and after 43 days of annealing in air it improved to a 14% loss. The formulated sample consisted of 70 parts by weight of Dow polystyrene, 30 pbw of pentaphenyltrimethyltrisiloxane (Dow Corning DC 705 oil), 2 pbw of p-terphenyl, 0.2 pbw of tetraphenylbutadiene, and 0.5 pbw of UVASIL299LM from Ferro

  6. Nanophosphor composite scintillator with a liquid matrix

    Science.gov (United States)

    McKigney, Edward Allen; Burrell, Anthony Keiran; Bennett, Bryan L.; Cooke, David Wayne; Ott, Kevin Curtis; Bacrania, Minesh Kantilal; Del Sesto, Rico Emilio; Gilbertson, Robert David; Muenchausen, Ross Edward; McCleskey, Thomas Mark

    2010-03-16

    An improved nanophosphor scintillator liquid comprises nanophosphor particles in a liquid matrix. The nanophosphor particles are optionally surface modified with an organic ligand. The surface modified nanophosphor particle is essentially surface charge neutral, thereby preventing agglomeration of the nanophosphor particles during dispersion in a liquid scintillator matrix. The improved nanophosphor scintillator liquid may be used in any conventional liquid scintillator application, including in a radiation detector.

  7. Improvements to well scintillation counters

    International Nuclear Information System (INIS)

    Farukhi, M.R.; Mataraza, G.A.; Wimer, O.D.

    1977-01-01

    This invention relates to the field of ionising radiation detection. It concerns in particular scintillation detectors of the type that is commonly used in conjunction with a photomultiplier tube and that is used for monitoring radiation, for instance in the clinical measurements of isotopes. This invention enables well scintillation counters to be made, characterised by a high efficiency in measuring the thindown rate of radio-pharmaceutical solutions and to resolve the distribution of energy emanating from the radioactive source. It particularly consists in improving the uniformity of the luminous efficiency, the quality of the resolution and the efficiency whilst improving the reception of light [fr

  8. Magnetic fields and scintillator performance

    International Nuclear Information System (INIS)

    Green, D.; Ronzhin, A.; Hagopian, V.

    1995-06-01

    Experimental data have shown that the light output of a scintillator depends on the magnitude of the externally applied magnetic fields, and that this variation can affect the calorimeter calibration and possibly resolution. The goal of the measurements presented here is to study the light yield of scintillators in high magnetic fields in conditions that are similar to those anticipated for the LHC CMS detector. Two independent measurements were performed, the first at Fermilab and the second at the National High Magnetic Field Laboratory at Florida State University

  9. Development of scintillating fiber tracker

    International Nuclear Information System (INIS)

    Ishikawa, Shuzo; Kawai, Toshihide; Kozaki, Tetsuo

    1995-01-01

    In order to use thin scintillating fiber (diameter 500 micron) as a particle tracking detector, we have developed a method to construct precise multi-layer scintillating fiber sheets. We have also developed dedicated machines for this purpose. This paper presents the details of the method and the machines. Using these machines, we have produced fiber sheets for CERN WA95/CHORUS, which intend to detect a neutrino oscillation in the νμ-ντ channel using Hybrid Emulsion Set-up. Fiber Trackers are used as a vertex detector which support the neutrino event location in the nuclear emulsion target. (author)

  10. Study of micro pixel photon counters for a high granularity scintillator-based hadron calorimeter

    International Nuclear Information System (INIS)

    D'Ascenzo, N.; Eggemann, A.; Garutti, E.

    2007-11-01

    A new Geiger mode avalanche photodiode, the Micro Pixel Photon Counter (MPPC), was recently released by Hamamatsu. It has a high photo-detection efficiency in the 420 nm spectral region. This product can represent an elegant candidate for the design of a high granularity scintillator based hadron calorimeter for the International Linear Collider. In fact, the direct readout of the blue scintillation photons with a MPPC is a feasible techological solution. The readout of a plastic scintillator by a MPPC, both mediated by the traditional wavelength shifting fiber, and directly coupled, has been systematically studied. (orig.)

  11. Time resolution research in liquid scintillating detection

    International Nuclear Information System (INIS)

    He Hongkun; Shi Haoshan

    2006-01-01

    The signal processing design method is introduced into liquid scintillating detection system design. By analyzing the signal of liquid scintillating detection, improving time resolution is propitious to upgrade efficiency of detecting. The scheme of realization and satisfactory experiment data is demonstrated. Besides other types of liquid scintillating detection is the same, just using more high speed data signal processing techniques and elements. (authors)

  12. Composite scintillators for detection of ionizing radiation

    Science.gov (United States)

    Dai, Sheng [Knoxville, TN; Stephan, Andrew Curtis [Knoxville, TN; Brown, Suree S [Knoxville, TN; Wallace, Steven A [Knoxville, TN; Rondinone, Adam J [Knoxville, TN

    2010-12-28

    Applicant's present invention is a composite scintillator having enhanced transparency for detecting ionizing radiation comprising a material having optical transparency wherein said material comprises nano-sized objects having a size in at least one dimension that is less than the wavelength of light emitted by the composite scintillator wherein the composite scintillator is designed to have selected properties suitable for a particular application.

  13. Photonic crystal scintillators and methods of manufacture

    Science.gov (United States)

    Torres, Ricardo D.; Sexton, Lindsay T.; Fuentes, Roderick E.; Cortes-Concepcion, Jose

    2015-08-11

    Photonic crystal scintillators and their methods of manufacture are provided. Exemplary methods of manufacture include using a highly-ordered porous anodic alumina membrane as a pattern transfer mask for either the etching of underlying material or for the deposition of additional material onto the surface of a scintillator. Exemplary detectors utilizing such photonic crystal scintillators are also provided.

  14. Impact of geometry on light collection efficiency of scintillation detectors for cryogenic rare event searches

    International Nuclear Information System (INIS)

    Danevich, F.A.; Kobychev, V.V.; Kobychev, R.V.; Kraus, H.; Mikhailik, V.B.; Mokina, V.M.; Solsky, I.M.

    2014-01-01

    Simulations of photon propagation in scintillation detectors were performed with the aim to find the optimal scintillator geometry, surface treatment, and shape of external reflector in order to achieve maximum light collection efficiency for detector configurations that avoid direct optical coupling, a situation that is commonly found in cryogenic scintillating bolometers in experimental searches for double beta decay and dark matter. To evaluate the light collection efficiency of various geometrical configurations we used the ZEMAX ray-tracing software. It was found that scintillators in the shape of a triangular prism with an external mirror shaped as truncated cone gives the highest light collection efficiency. The results of the simulations were confirmed by carrying out measurements of the light collection efficiencies of CaWO 4 crystal scintillators. A comparison of simulated and measured values of light output shows good agreement

  15. BC404 scintillators as gamma locators studied via Geant4 simulations

    Science.gov (United States)

    Cortés, M. L.; Hoischen, R.; Eisenhauer, K.; Gerl, J.; Pietralla, N.

    2014-05-01

    In many applications in industry and academia, an accurate determination of the direction from where gamma rays are emitted is either needed or desirable. Ion-beam therapy treatments, the search for orphan sources, and homeland security applications are examples of fields that can benefit from directional sensitivity to gamma-radiation. Scintillation detectors are a good option for these types of applications as they have relatively low cost, are easy to handle and can be produced in a large range of different sizes. In this work a Geant4 simulation was developed to study the directional sensitivity of different BC404 scintillator geometries and arrangements. The simulation includes all the physical processes relevant for gamma detection in a scintillator. In particular, the creation and propagation of optical photons inside the scintillator was included. A simplified photomultiplier tube model was also simulated. The physical principle exploited is the angular dependence of the shape of the energy spectrum obtained from thin scintillator layers when irradiated from different angles. After an experimental confirmation of the working principle of the device and a check of the simulation, the possibilities and limitations of directional sensitivity to gamma radiation using scintillator layers was tested. For this purpose, point-like sources of typical energies expected in ion-beam therapy were used. Optimal scintillator thicknesses for different energies were determined and the setup efficiencies calculated. The use of arrays of scintillators to reconstruct the direction of incoming gamma rays was also studied. For this case, a spherical source emitting Bremsstrahlung radiation was used together with a setup consisting of scintillator layers. The capability of this setup to identify the center of the extended source was studied together with its angular resolution.

  16. Synthesis of plastic scintillation microspheres: Evaluation of scintillators

    International Nuclear Information System (INIS)

    Santiago, L.M.; Bagán, H.; Tarancón, A.; Garcia, J.F.

    2013-01-01

    The use of plastic scintillation microspheres (PSm) appear to be an alternative to liquid scintillation for the quantification of alpha and beta emitters because it does not generate mixed wastes after the measurement (organic and radioactive). In addition to routine radionuclide determinations, PSm can be used for further applications, e.g. for usage in a continuous monitoring equipment, for measurements of samples with a high salt concentration and for an extractive scintillation support which permits the separation, pre-concentration and measurement of the radionuclides without additional steps of elution and sample preparation. However, only a few manufacturers provide PSm, and the low number of regular suppliers reduces its availability and restricts the compositions and sizes available. In this article, a synthesis method based on the extraction/evaporation methodology has been developed and successfully used for the synthesis of plastic scintillation microspheres. Seven different compositions of plastic scintillation microspheres have been synthesised; PSm1 with polystyrene, PSm2 with 2,5-Diphenyloxazol(PPO), PSm3 with p-terphenyl (pT), PSm4 with PPO and 1,4-bis(5-phenyloxazol-2-yl) (POPOP), PSm5 pT and (1,4-bis [2-methylstyryl] benzene) (Bis-MSB), PSm6 with PPO, POPOP and naphthalene and PSm7 with pT, Bis-MSB and naphthalene. The synthesised plastic scintillation microspheres have been characterised in terms of their morphology, detection capabilities and alpha/beta separation capacity. The microspheres had a median diameter of approximately 130 μm. Maximum detection efficiency values were obtained for the PSm4 composition as follows 1.18% for 3 H, 51.2% for 14 C, 180.6% for 90 Sr/ 90 Y and 76.7% for 241 Am. Values of the SQP(E) parameter were approximately 790 for PSm4 and PSm5. These values show that the synthesised PSm exhibit good scintillation properties and that the spectra are at channel numbers higher than in commercial PSm. Finally, the addition

  17. Cherenkov and scintillation light separation on the CheSS experiment

    Science.gov (United States)

    Caravaca, Javier; Land, Benjamin; Descamps, Freija; Orebi Gann, Gabriel D.

    2016-09-01

    Separation of the scintillation and Cherenkov light produced in liquid scintillators enables outstanding capabilities for future particle detectors, the most relevant being: particle directionality information in a low energy threshold detector and improved particle identification. The CheSS experiment uses an array of small, fast photomultipliers (PMTs) and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in liquid scintillator using two techniques: based on the photon density and using the photon hit time information. A charged particle ionizing a scintillation medium produces a prompt Cherenkov cone and late isotropic scintillation light, typically delayed by several ns. The fast response of our PMTs and DAQ provides a precision well below the ns level, making possible the time separation. Furthermore, the usage of the new developed water-based liquid scintillators (WbLS) enhances the separation since it allows tuning of the Cherenkov/Scintillation ratio. Latest results on the separation for pure liquid scintillators and WbLS will be presented.

  18. Shock-resistant scintillation detector

    International Nuclear Information System (INIS)

    Novak, W.P.

    1979-01-01

    A unique scintillation detector unit is disclosed which employs a special light transfer and reflector means that encases and protects the scintillator crystal against high g forces. The light transfer means comprises a flexible silicon rubber optical material bonded between the crystal and the optical window and having an axial thickness sufficient to allow the scintillator to move axially inside the container under high g forces without destroying the bonds. The reflector means comprises a soft elastic silicone rubber sleeve having a multiplicity of closely arranged tapered protrusions radiating toward and engaging the periphery of the scintillator crystal to cushion shocks effectively and having a reflective material, such as aluminum oxide powder, in the spaces between the protrusions. The reflector means provides improved shock absorption because of the uniform support and cushioning action of the protrusions and also provides the detector with high efficiency. The silicon rubber composition is specially compounded to include a large amount of aluminum oxide which enables the rubber to function effectively as a light reflector

  19. Scintillating ribbon x-ray detector

    International Nuclear Information System (INIS)

    Kinchen, B.E.; Rogers, A.

    1995-01-01

    A patent in the early 1970's by Aerojet Corporation in Sacramento, CA put forth the idea of using an array of scintillating fibers for x-ray detection and imaging. In about 1975, Pratt and Whitney Aircraft in East Hartford, CT designed and manufactured an imaging system based on the patent. The device was 1.75 in thick in the direction of the x-ray beam and about 4 in. by 4 in. square. The device was used with a 8 MeV x-ray source to image and measure internal clearances within operating aircraft, gas turbines engines. There are significant advantages of fiber optic detectors in x-ray detection. However, the advantages are often outweighed by the disadvantages. Two of the advantages of scintillating fiber optic x-ray detectors are: (1) high limiting spatial frequency -- between 20 and 25 lp/mm; and (2) excellent x-ray stopping power -- they can be made thick and retain spatial resolution. In traditional fiber optic detectors the x-rays are oriented parallel to the long axis of the fiber. For the scintillating ribbon x-ray sensor, the x-rays are oriented normal to the fiber long axis. This ribbon sensor technique has a number of advantages over the two current radiographic techniques digital x-radiography and x-ray film: The main advantage the ribbon has is size and shape. It can be as thin as 0.05 in., virtually any width or length, and flexible. Once positioned in a given location, 20 to 100 square inches of the object being inspected can be imaged with a single x-ray beam sweep. It is clear that conventional digital cameras do not lend themselves to placement between walls of aircraft structures or similar items requiring x-ray inspections. A prototype scintillating ribbon x-ray sensor has been fabricated and tested by Synergistic Detector Designs. Images were acquired on corrosion test panels of aluminum fabricated by Iowa State University

  20. Extruded plastic scintillator for MINERvA

    International Nuclear Information System (INIS)

    Pla-Dalmau, Anna; Bross, Alan D.; FermilabRykalin, Victor V.; Wood, Brian M.; NICADD, DeKalb

    2005-01-01

    An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. A new experiment at Fermilab is pursuing the use of extruded plastic scintillator. A new plastic scintillator strip is being tested and its properties characterized. The initial results are presented here

  1. Development of in-situ radon sensor using plastic scintillator

    International Nuclear Information System (INIS)

    Shitashima, Kiminori

    2009-01-01

    Underwater in-situ radon measurement is important scientific priority for oceanography, especially for survey and monitoring of submarine groundwater discharge (SDG). The high sensitivity and lightweight underwater in-situ radon sensor using NaI(Tl) doped plastic scintillator was developed for application to SDG research. Because NaI(Tl) doped plastic scintillator contacts seawater directly, the plastic scintillator can expect high sensitivity in comparison with NaI(Tl) crystal sealed in a container. In order to improve condensation efficiency of scintillation, the plastic scintillator was processed in funnel form and coated by light-resistant paint. This sensor consists of plastic scintillator, photomultiplier tube, preamplifier unit, high-voltage power supply, data logger and lithium-ion battery, and all parts are stored in a pressure housing (200φx300L). The newly developed underwater in-situ radon sensor was tested at hydrothermal area (underwater hot springs) that the hydrothermal fluid containing high concentration of radon is discharged into seawater. The sensor was operated by a diver, and sensitivity tests and mapping survey for estimation of radon diffusion were carried out. The signals of the radon sensor ranged from 20 to 65 mV, and these signals corresponded with radon concentration of 2 to 12 becquerels per liter. The sensor was able to detect radon to 20 m above the hydrothermal point (seafloor). Since the sensor is small and light-weight, measurement, monitoring and mapping can perform automatically by installing the sensor to an AUV (autonomous underwater vehicle). Furthermore, underwater in-situ radon sensor is expected an application to earthquake prediction and volcanic activity monitoring as well as oceanography and hydrology. (author)

  2. Scintillators for positron emission tomography

    International Nuclear Information System (INIS)

    Moses, W.W.; Derenzo, S.E.

    1995-09-01

    Like most applications that utilize scintillators for gamma detection, Positron Emission Tomography (PET) desires materials with high light output, short decay time, and excellent stopping power that are also inexpensive, mechanically rugged, and chemically inert. Realizing that this ''ultimate'' scintillator may not exist, this paper evaluates the relative importance of these qualities and describes their impact on the imaging performance of PET. The most important PET scintillator quality is the ability to absorb 511 keV photons in a small volume, which affects the spatial resolution of the camera. The dominant factor is a short attenuation length (≤ 1.5 cm is required), although a high photoelectric fraction is also important (> 30% is desired). The next most important quality is a short decay time, which affects both the dead time and the coincidence timing resolution. Detection rates for single 511 keV photons can be extremely high, so decay times ≤ 500 ns are essential to avoid dead time losses. In addition, positron annihilations are identified by time coincidence so ≤5 ns fwhm coincidence pair timing resolution is required to identify events with narrow coincidence windows, reducing contamination due to accidental coincidences. Current trends in PET cameras are toward septaless, ''fully-3D'' cameras, which have significantly higher count rates than conventional 2-D cameras and so place higher demands on scintillator decay time. Light output affects energy resolution, and thus the ability of the camera to identify and reject events where the initial 511 keV photon has undergone Compton scatter in the patient. The scatter to true event fraction is much higher in fully-3D cameras than in 2-D cameras, so future PET cameras would benefit from scintillators with a 511 keV energy resolution < 10--12% fwhm

  3. Energy resolution of scintillation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Moszyński, M., E-mail: M.Moszynski@ncbj.gov.pl; Syntfeld-Każuch, A.; Swiderski, L.; Grodzicka, M.; Iwanowska, J.; Sibczyński, P.; Szczęśniak, T.

    2016-01-01

    According to current knowledge, the non-proportionality of the light yield of scintillators appears to be a fundamental limitation of energy resolution. A good energy resolution is of great importance for most applications of scintillation detectors. Thus, its limitations are discussed below; which arise from the non-proportional response of scintillators to gamma rays and electrons, being of crucial importance to the intrinsic energy resolution of crystals. The important influence of Landau fluctuations and the scattering of secondary electrons (δ-rays) on intrinsic resolution is pointed out here. The study on undoped NaI and CsI at liquid nitrogen temperature with a light readout by avalanche photodiodes strongly suggests that the non-proportionality of many crystals is not their intrinsic property and may be improved by selective co-doping. Finally, several observations that have been collected in the last 15 years on the influence of the slow components of light pulses on energy resolution suggest that more complex processes are taking place in the scintillators. This was observed with CsI(Tl), CsI(Na), ZnSe(Te), and undoped NaI at liquid nitrogen temperature and, finally, for NaI(Tl) at temperatures reduced below 0 °C. A common conclusion of these observations is that the highest energy resolution, and particularly intrinsic resolution measured with the scintillators, characterized by two or more components of the light pulse decay, is obtainable when the spectrometry equipment integrates the whole light of the components. In contrast, the slow components observed in many other crystals degrade the intrinsic resolution. In the limiting case, afterglow could also be considered as a very slow component that spoils the energy resolution. The aim of this work is to summarize all of the above observations by looking for their origin.

  4. Development of Omnidirectional Gamma-imager with Stacked Scintillators

    International Nuclear Information System (INIS)

    Takahashi, Tone; Kawarabayashi, Jun; Tomita, Hideki; Iguchi, Tetsuo; Takada, Eiji

    2013-06-01

    In the severe accident at nuclear power plant, a rapid measurement of radioactive fallout is required. So we have developed a Compton imager with high efficiency and omni-directional sensitivity. Three dimensional position resolutions were evaluated about several kinds of scintillators. The all-directional imaging was demonstrated by the simulation of detection of 137 Cs point source. Imaging quality with angle resolution of 28 deg. and detection efficiency of 1.1% was estimated. (authors)

  5. A new liquid xenon scintillation detector for positron emission tomography

    International Nuclear Information System (INIS)

    Chepel, V.Yu.

    1993-01-01

    A new positron-sensitive detector of annihilation photons filled with liquid xenon is proposed for positron emission tomography. Simultaneous detection of both liquid xenon scintillation and ionization current produces a time resolution of < 1 ns and a position resolution in the tangential direction of the tomograph ring is ∼ 1 mm and in the radial direction is ∼ 5 mm. The advantages of a tomograph with new detectors are discussed. New algorithms of Compton scattering can be used. (author)

  6. Data process of liquid scintillation counting

    International Nuclear Information System (INIS)

    Ishikawa, Hiroaki; Kuwajima, Susumu.

    1975-01-01

    The use of liquid scintillation counting system has been significantly spread because automatic sample changers and printers have recently come to be incorporated. However, the system will be systematized completely if automatic data processing and the sample preparation of radioactive materials to be measured are realized. Dry or wet oxidation method is applied to the sample preparation when radioactive materials are hard to dissolve into scintillator solution. Since these several years, the automatic sample combustion system, in which the dry oxidation is automated, has been rapidly spread and serves greatly to labor saving. Since the printers generally indicate only counted number, data processing system has been developed, and speeded up calculating process, which automatically corrects quenching of samples for obtaining the final radioactivity required. The data processing system is roughly divided into on-line and off-line systems according to whether computers are connected directly or indirectly, while its hardware is classified to input, calculating and output devices. Also, the calculation to determine sample activity by external standard method is explained. (Wakatsuki, Y.)

  7. Collimator trans-axial tomographic scintillation camera

    International Nuclear Information System (INIS)

    Jaszczak, Ronald J.

    1979-01-01

    An improved collimator is provided for a scintillation camera system that employs a detector head for transaxial tomographic scanning. One object of this invention is to significantly reduce the time required to obtain statistically significant data in radioisotope scanning using a scintillation camera. Another is to increase the rate of acceptance of radioactive events to contribute to the positional information obtainable from a radiation source of known strength without sacrificing spatial resolution. A further object is to reduce the necessary scanning time without degrading the images obtained. The collimator described has apertures defined by septa of different radiation transparency. The septa are aligned to provide greater radiation shielding from gamma radiation travelling within planes perpendicular to the cranial-caudal axis and less radiation shielding from gamma radiation travelling within other planes. Septa may also define apertures such that the collimator provides high spatial resolution of gamma rays traveling within planes perpendicular to the cranial-caudal axis and directed at the detector and high radiation sensitivity to gamma radiation travelling other planes and indicated at the detector. (LL)

  8. Liquid Scintillation Detectors for High Energy Neutrinos

    International Nuclear Information System (INIS)

    Smith, Stefanie N.; Learned, John G.

    2010-01-01

    Large open volume (not segmented) liquid scintillation detectors have been generally dedicated to low energy neutrino measurements, in the MeV energy region. We describe the potential employment of large detectors (>1 kiloton) for studies of higher energy neutrino interactions, such as cosmic rays and long-baseline experiments. When considering the physics potential of new large instruments the possibility of doing useful measurements with higher energy neutrino interactions has been overlooked. Here we take into account Fermat's principle, which states that the first light to reach each PMT will follow the shortest path between that PMT and the point of origin. We describe the geometry of this process, and the resulting wavefront, which we are calling the 'Fermat surface', and discuss methods of using this surface to extract directional track information and particle identification. This capability may be demonstrated in the new long-baseline neutrino beam from Jaeri accelerator to the KamLAND detector in Japan. Other exciting applications include the use of Hanohano as a movable long-baseline detector in this same beam, and LENA in Europe for future long-baseline neutrino beams from CERN. Also, this methodology opens up the question as to whether a large liquid scintillator detector should be given consideration for use in a future long-baseline experiment from Fermilab to the DUSEL underground laboratory at Homestake.

  9. High Efficiency, Low Cost Scintillators for PET

    International Nuclear Information System (INIS)

    Kanai Shah

    2007-01-01

    Inorganic scintillation detectors coupled to PMTs are an important element of medical imaging applications such as positron emission tomography (PET). Performance as well as cost of these systems is limited by the properties of the scintillation detectors available at present. The Phase I project was aimed at demonstrating the feasibility of producing high performance scintillators using a low cost fabrication approach. Samples of these scintillators were produced and their performance was evaluated. Overall, the Phase I effort was very successful. The Phase II project will be aimed at advancing the new scintillation technology for PET. Large samples of the new scintillators will be produced and their performance will be evaluated. PET modules based on the new scintillators will also be built and characterized

  10. Silicon photomultipliers for scintillating trackers

    Energy Technology Data Exchange (ETDEWEB)

    Rabaioli, S., E-mail: simone.rabaioli@gmail.com [Universita degli Studi dell' Insubria, Via Valleggio, 11 - 22100 Como (Italy); Berra, A.; Bolognini, D. [Universita degli Studi dell' Insubria, Via Valleggio, 11 - 22100 Como (Italy); INFN sezione di Milano Bicocca (Italy); Bonvicini, V. [INFN sezione di Trieste (Italy); Bosisio, L. [Universita degli Studi di Trieste and INFN sezione di Trieste (Italy); Ciano, S.; Iugovaz, D. [INFN sezione di Trieste (Italy); Lietti, D. [Universita degli Studi dell' Insubria, Via Valleggio, 11 - 22100 Como (Italy); INFN sezione di Milano Bicocca (Italy); Penzo, A. [INFN sezione di Trieste (Italy); Prest, M. [Universita degli Studi dell' Insubria, Via Valleggio, 11 - 22100 Como (Italy); INFN sezione di Milano Bicocca (Italy); Rashevskaya, I.; Reia, S. [INFN sezione di Trieste (Italy); Stoppani, L. [Universita degli Studi dell' Insubria, Via Valleggio, 11 - 22100 Como (Italy); Vallazza, E. [INFN sezione di Trieste (Italy)

    2012-12-11

    In recent years, silicon photomultipliers (SiPMs) have been proposed as a new kind of readout device for scintillating detectors in many experiments. A SiPM consists of a matrix of parallel-connected pixels, which are independent photon counters working in Geiger mode with very high gain ({approx}10{sup 6}). This contribution presents the use of an array of eight SiPMs (manufactured by FBK-irst) for the readout of a scintillating bar tracker (a small size prototype of the Electron Muon Ranger detector for the MICE experiment). The performances of the SiPMs in terms of signal to noise ratio, efficiency and time resolution will be compared to the ones of a multi-anode photomultiplier tube (MAPMT) connected to the same bars. Both the SiPMs and the MAPMT are interfaced to a VME system through a 64 channel MAROC ASIC.

  11. Silicon photomultipliers for scintillating trackers

    Science.gov (United States)

    Rabaioli, S.; Berra, A.; Bolognini, D.; Bonvicini, V.; Bosisio, L.; Ciano, S.; Iugovaz, D.; Lietti, D.; Penzo, A.; Prest, M.; Rashevskaya, I.; Reia, S.; Stoppani, L.; Vallazza, E.

    2012-12-01

    In recent years, silicon photomultipliers (SiPMs) have been proposed as a new kind of readout device for scintillating detectors in many experiments. A SiPM consists of a matrix of parallel-connected pixels, which are independent photon counters working in Geiger mode with very high gain (∼106). This contribution presents the use of an array of eight SiPMs (manufactured by FBK-irst) for the readout of a scintillating bar tracker (a small size prototype of the Electron Muon Ranger detector for the MICE experiment). The performances of the SiPMs in terms of signal to noise ratio, efficiency and time resolution will be compared to the ones of a multi-anode photomultiplier tube (MAPMT) connected to the same bars. Both the SiPMs and the MAPMT are interfaced to a VME system through a 64 channel MAROC ASIC.

  12. LHCb Upgrade: Scintillating Fibre Tracker

    International Nuclear Information System (INIS)

    Tobin, Mark

    2016-01-01

    The LHCb detector will be upgraded during the Long Shutdown 2 (LS2) of the LHC in order to cope with higher instantaneous luminosities and to read out the data at 40 MHz using a trigger-less read-out system. All front-end electronics will be replaced and several sub-detectors must be redesigned to cope with higher occupancy. The current tracking detectors downstream of the LHCb dipole magnet will be replaced by the Scintillating Fibre (SciFi) Tracker. The SciFi Tracker will use scintillating fibres read out by Silicon Photomultipliers (SiPMs). State-of-the-art multi-channel SiPM arrays are being developed to read out the fibres and a custom ASIC will be used to digitise the signals from the SiPMs. The evolution of the design since the Technical Design Report in 2014 and the latest R & D results are presented.

  13. Studies of novel plastic scintillators

    International Nuclear Information System (INIS)

    McInally, I.D.

    1979-08-01

    The general aim of this study was to synthesize fluorescent compounds which are capable of polymerisation, to prepare polymers and co-polymers from these compounds and to study the photophysical properties of these materials. In this way it is hoped to produce plastic scintillators exhibiting improved energy transfer efficiency. Materials studied included POS(2-phenyl-5-(p vinyl) phenyloxazole) vinyl naphthalene, methyl anthracene terminated poly vinyl toluene) and derivatives of BuPBD. (author)

  14. New scintillating media based on liquid crystals for particle detectors

    International Nuclear Information System (INIS)

    Barnik, M.I.; Yudin, S.G.; Vasil'chenko, V.G.; Golovkin, S.V.; Medvedkov, A.M.; Solovjev, A.S.

    2000-01-01

    The study results of optical, photoluminiscent and scintillation properties of a liquid crystal 4-pentyl-4'-cyanobiphenyl are presented. The scintillation light output of this liquid crystal is about 35% of crystal anthracene, its main decay time constants are 4 and 14 ns, and the maximum of light emission spectrum is about 400 nm. The light output of a dissolution of green emitting light scintillation dopant R6 in the liquid crystal is about 120% of crystal anthracene. The light output of the frozen dissolution measured at -112 deg. C is about 2.5 times higher as observed at +20 deg. C. In the uniaxially oriented liquid crystal, the predominant intensity direction of emitted light is pointed perpendicular to the liquid crystal director and an appreciable part of the emitted light is elliptically polarized. The possibility to use scintillation properties of liquid crystals is considered both for the improvement of existing particle detector characteristics and for the creation of new gated particle detectors

  15. New scintillating media based on liquid crystals for particle detectors

    CERN Document Server

    Barnik, M I; Vasilchenko, V G; Golovkin, S V; Medvedkov, A M; Soloviev, A S

    2000-01-01

    The study results of optical, photoluminiscent and scintillation properties of a liquid crystal 4-pentyl-4'-cyanobiphenyl are presented. The scintillation light output of this liquid crystal is about 35% of crystal anthracene, its main decay time constants are 4 and 14 ns, and the maximum of light emission spectrum is about 400 nm. The light output of a dissolution of green emitting light scintillation dopant R6 in the liquid crystal is about 120% of crystal anthracene. The light output of the frozen dissolution measured at -112 deg. C is about 2.5 times higher as observed at +20 deg. C. In the uniaxially oriented liquid crystal, the predominant intensity direction of emitted light is pointed perpendicular to the liquid crystal director and an appreciable part of the emitted light is elliptically polarized. The possibility to use scintillation properties of liquid crystals is considered both for the improvement of existing particle detector characteristics and for the creation of new gated particle detectors.

  16. Collimated trans-axial tomographic scintillation camera

    International Nuclear Information System (INIS)

    1980-01-01

    The principal problem in trans-axial tomographic radioisotope scanning is the length of time required to obtain meaningful data. Patient movement and radioisotope migration during the scanning period can cause distortion of the image. The object of this invention is to reduce the scanning time without degrading the images obtained. A system is described in which a scintillation camera detector is moved to an orbit about the cranial-caudal axis relative to the patient. A collimator is used in which lead septa are arranged so as to admit gamma rays travelling perpendicular to this axis with high spatial resolution and those travelling in the direction of the axis with low spatial resolution, thus increasing the rate of acceptance of radioactive events to contribute to the positional information obtainable without sacrificing spatial resolution. (author)

  17. Charged particle scintillation mass spectrometer

    International Nuclear Information System (INIS)

    Baranov, P.S.; Zhuravlev, E.E.; Nafikov, A.A.; Osadchi , A.I.; Raevskij, V.G.; Smirnov, P.A.; Cherepnya, S.N.; Yanulis, Yu.P.

    1982-01-01

    A scintillation mass-spectrometer for charged particle identification by the measured values of time-of-flight and energy operating on line with the D-116 computer is described. Original time detectors with 100x100x2 mm 3 and 200x2 mm 2 scintillators located on the 1- or 2 m path length are used in the spectrometer. The 200x200x200 mm 3 scintillation unit is used as a E-counter. Time-of-flight spectra of the detected particles on the 2 m path length obtained in spectrometer test in the beam of charged particles escaping from the carbon target at the angle of 130 deg under 1.2 GeV bremsstrahlung beam of the ''Pakhra'' PIAS synchrotron are presented. Proton and deuteron energy spectra as well as mass spectrum of all the particles detected by the spectrometer are given. Mass resolution obtained on the 2 m path length for π-mesons is +-25%, for protons is +-5%, for deuterons is +-3%

  18. Ionospheric scintillation monitoring and modelling

    Directory of Open Access Journals (Sweden)

    Mariusz Pozoga

    2009-06-01

    Full Text Available

    This paper presents a review of the ionospheric scintillation monitoring and modelling by the European groups

    involved in COST 296. Several of these groups have organized scintillation measurement campaigns at low and

    high latitudes. Some characteristic results obtained from the measured data are presented. The paper also addresses the modeling activities: four models, based on phase screen techniques, with different options and application domains are detailed. Finally some new trends for research topics are given. This includes the wavelet analysis, the high latitudes analysis, the construction of scintillation maps and the mitigation techniques.


  19. Characterization of scintillator-based detectors for few-ten-keV high-spatial-resolution x-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Jakob C., E-mail: jakob.larsson@biox.kth.se; Lundström, Ulf; Hertz, Hans M. [Biomedical and X-ray Physics, Department of Applied Physics, KTH Royal Institute of Technology/Albanova, Stockholm 10691 (Sweden)

    2016-06-15

    Purpose: High-spatial-resolution x-ray imaging in the few-ten-keV range is becoming increasingly important in several applications, such as small-animal imaging and phase-contrast imaging. The detector properties critically influence the quality of such imaging. Here the authors present a quantitative comparison of scintillator-based detectors for this energy range and at high spatial frequencies. Methods: The authors determine the modulation transfer function, noise power spectrum (NPS), and detective quantum efficiency for Gadox, needle CsI, and structured CsI scintillators of different thicknesses and at different photon energies. An extended analysis of the NPS allows for direct measurements of the scintillator effective absorption efficiency and effective light yield as well as providing an alternative method to assess the underlying factors behind the detector properties. Results: There is a substantial difference in performance between the scintillators depending on the imaging task but in general, the CsI based scintillators perform better than the Gadox scintillators. At low energies (16 keV), a thin needle CsI scintillator has the best performance at all frequencies. At higher energies (28–38 keV), the thicker needle CsI scintillators and the structured CsI scintillator all have very good performance. The needle CsI scintillators have higher absorption efficiencies but the structured CsI scintillator has higher resolution. Conclusions: The choice of scintillator is greatly dependent on the imaging task. The presented comparison and methodology will assist the imaging scientist in optimizing their high-resolution few-ten-keV imaging system for best performance.

  20. Multi element high resolution scintillator structure

    International Nuclear Information System (INIS)

    Cusano, D.A.

    1980-01-01

    A gamma camera scintillator structure, suitable for detecting high energy gamma photons which, in a single scintillator camera, would require a comparatively thick scintillator crystal, so resulting in unacceptable dispersion of light photons, comprises a collimator array of a high Z material with elongated, parallel wall channels with the scintillator material being disposed in one end of the channels so as to form an integrated collimator/scintillator structure. The collimator channel walls are preferably coated with light reflective material and further light reflective surfaces being translucent to gamma photons, may be provided in each channel. The scintillators may be single crystals or preferably comprise a phosphor dispersed in a thermosetting translucent matrix as disclosed in GB2012800A. The light detectors of the assembled camera may be photomultiplier tubes charge coupled devices or charge injection devices. (author)

  1. 4 GHz ionospheric scintillations observed at Taipei

    International Nuclear Information System (INIS)

    Huang, Y.N.; Jeng, B.S.

    1978-01-01

    In a study of ionospheric scintillations 3950 MHz beacon signals from geostationary communication satellites Intelsat-IV-F8 and Intelsat-IV-F1 were recorded on a strip chart and magnetic tape at the Taipei Earth Station. While the strip charts were used to monitor the occurrence of the scintillation, the magnetic tape output was digitized and processed by a computerized system to yield a detailed analysis of scintillation events. It was found that diurnal variations were similar to the diurnal patterns of sporadic E at greater than 5 MHz and VHF band ionospheric scintillations during daytime as reported by Huang (1978). Eight typical scintillation events were selected for the calculation of the scintillation index, S4, and other parameters. The mean S4 index for the 8 events was found to be 0.15. Numerical and graphic results are presented for the cumulative amplitude distributions, message reliability, autocorrelation functions and power spectra

  2. A Review of Ionospheric Scintillation Models.

    Science.gov (United States)

    Priyadarshi, S

    This is a general review of the existing climatological models of ionospheric radio scintillation for high and equatorial latitudes. Trans-ionospheric communication of radio waves from transmitter to user is affected by the ionosphere which is highly variable and dynamic in both time and space. Scintillation is the term given to irregular amplitude and phase fluctuations of the received signals and related to the electron density irregularities in the ionosphere. Key sources of ionospheric irregularities are plasma instabilities; every irregularities model is based on the theory of radio wave propagation in random media. It is important to understand scintillation phenomena and the approach of different theories. Therefore, we have briefly discussed the theories that are used to interpret ionospheric scintillation data. The global morphology of ionospheric scintillation is also discussed briefly. The most important (in our opinion) analytical and physical models of scintillation are reviewed here.

  3. Morphology of auroral zone radio wave scintillation

    International Nuclear Information System (INIS)

    Rino, C.L.; Matthews, S.J.

    1980-01-01

    This paper describes the morphology of midnight sector and morning sector auroral zone scintillation observations made over a two-year period using the Wideband satelite, which is in a sun-synchronous, low-altitude orbit. No definitive seasonal variation was found. The nighttime data showed the highest scintillation ocurrence levels, but significant amounts of morning scintillation were observed. For the most part the scintillation activity followed the general pattern of local magnetic activity. The most prominent feature in the nightime data is a localized amplitude and phase scintillation enhancement at the point where the propagation vector lies within an L shell. A geometrical effect due to a dynamic slab of sheetlike structures in the F region is hypothesized as the source of his enhancement. The data have been sorted by magnetic activity, proximity to local midnight, and season. The general features of the data are in agreement with the accepted morphology of auroral zone scintillation

  4. Patient restraining device for the pinhole collimator and gamma scintillation camera

    International Nuclear Information System (INIS)

    Kay, T.D.

    1977-01-01

    A patient restraining device for use with the pinhole collimator of a conventional Gamma Scintillation Camera, the restraining device being made of an adapter ring and a patient holder. The adapter ring is secured directly to the pinhole collimator while the holder is adjustably mounted on the adapter. The adapter ring is so designed to accommodate a variety of holders so as to enable the scanning of many different areas of a patient's anatomy by the scintillation camera

  5. Surface coatings as xenon diffusion barriers on plastic scintillators : Improving Nuclear-Test-Ban Treaty verification

    OpenAIRE

    Bläckberg, Lisa

    2011-01-01

    This thesis investigates the ability of transparent surface coatings to reduce xenon diffusion into plastic scintillators. The motivation for the work is improved radioxenon monitoring equipment, used with in the framework of the verification regime of the Comprehensive Nuclear-Test-Ban Treaty. A large part of the equipment used in this context incorporates plastic scintillators which are in direct contact with the radioactive gas to be detected. One problem with such setup is that radioxenon...

  6. Scintillation properties of quantum-dot doped styrene based plastic scintillators

    International Nuclear Information System (INIS)

    Park, J.M.; Kim, H.J.; Hwang, Y.S.; Kim, D.H.; Park, H.W.

    2014-01-01

    We fabricated quantum-dot doped plastic scintillators in order to control the emission wavelength. We studied the characterization of the quantum-dots (CdSe/ZnS) and PPO (2, 5-diphenyloxazole) doped styrene based plastic scintillators. PPO is usually used as a dopant to enhance the scintillation properties of organic scintillators with a maximum emission wavelength of 380 nm. In order to study the scintillation properties of the quantum-dots doped plastic scintillators, the samples were irradiated with X-ray, photon, and 45 MeV proton beams. We observed that only PPO doped plastic scintillators shows a luminescence peak around 380 nm. However, both the quantum-dots and PPO doped plastic scintillators shows luminescence peaks around 380 nm and 520 nm. Addition of quantum-dots had shifted the luminescence spectrum from 380 nm (PPO) toward the region of 520 nm (Quantum-dots). Emissions with wavelength controllable plastic scintillators can be matched to various kinds of photosensors such as photomultiplier tubes, photo-diodes, avalanche photo-diodes, and CCDs, etc. Also quantum-dots doped plastic scintillator, which is irradiated 45 MeV proton beams, shows that the light yield of quantum-dots doped plastic scintillator is increases as quantum-dots doping concentration increases at 520 nm. And also the plastic scintillators were irradiated with Cs-137 γ-ray for measuring fluorescence decay time. -- Highlights: • Quantum-dot doped plastic scintillator is grown by the thermal polymerization method. • Quantum-dot doped plastic scintillators can control the emission wavelength to match with photo-sensor. • Quantum-dots and PPO doped plastic scintillators emitted luminescence peaks around 380 nm and 520 nm. • We observed the energy transfer from PPO to quantum-dot in the quantum-dot doped plastic scintillator

  7. Scintillation properties of quantum-dot doped styrene based plastic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.M.; Kim, H.J., E-mail: hongjooknu@gmail.com; Hwang, Y.S.; Kim, D.H.; Park, H.W.

    2014-02-15

    We fabricated quantum-dot doped plastic scintillators in order to control the emission wavelength. We studied the characterization of the quantum-dots (CdSe/ZnS) and PPO (2, 5-diphenyloxazole) doped styrene based plastic scintillators. PPO is usually used as a dopant to enhance the scintillation properties of organic scintillators with a maximum emission wavelength of 380 nm. In order to study the scintillation properties of the quantum-dots doped plastic scintillators, the samples were irradiated with X-ray, photon, and 45 MeV proton beams. We observed that only PPO doped plastic scintillators shows a luminescence peak around 380 nm. However, both the quantum-dots and PPO doped plastic scintillators shows luminescence peaks around 380 nm and 520 nm. Addition of quantum-dots had shifted the luminescence spectrum from 380 nm (PPO) toward the region of 520 nm (Quantum-dots). Emissions with wavelength controllable plastic scintillators can be matched to various kinds of photosensors such as photomultiplier tubes, photo-diodes, avalanche photo-diodes, and CCDs, etc. Also quantum-dots doped plastic scintillator, which is irradiated 45 MeV proton beams, shows that the light yield of quantum-dots doped plastic scintillator is increases as quantum-dots doping concentration increases at 520 nm. And also the plastic scintillators were irradiated with Cs-137 γ-ray for measuring fluorescence decay time. -- Highlights: • Quantum-dot doped plastic scintillator is grown by the thermal polymerization method. • Quantum-dot doped plastic scintillators can control the emission wavelength to match with photo-sensor. • Quantum-dots and PPO doped plastic scintillators emitted luminescence peaks around 380 nm and 520 nm. • We observed the energy transfer from PPO to quantum-dot in the quantum-dot doped plastic scintillator.

  8. Measurements of energy resolution with hemispheric scintillators

    International Nuclear Information System (INIS)

    Mendonca, A.C.S.; Binns, D.A.C.; Tauhata, L.; Poledna, R.

    1980-01-01

    The hemispheric configuration is used for plastic scintillators type NE 102 with the aiming to optimize the light collect. Scintillators at this configuration, with radii of 3,81 cm and 2,54 cm, are showing improvement about 16-17% in the energy resolution, on cilyndric scintillators with the same volume, for gamma rays of 511-1275 KeV. (E.G.) [pt

  9. Random wave fields and scintillated beams

    CSIR Research Space (South Africa)

    Roux, FS

    2009-01-01

    Full Text Available F. Stef Roux CSIR National Laser Centre PO Box 395, Pretoria 0001, South Africa CSIR National Laser Centre – p.1/29 Contents . Scintillated beams and adaptive optics . Detecting a vortex — Shack-Hartmann . Remove optical vortices . Random vortex... beam. CSIR National Laser Centre – p.3/29 Weak scintillation If the scintillation is weak the resulting phase function of the optical beam is still continuous. Such a weakly scintillated beam can be corrected by an adaptive optical system. CSIR National...

  10. High-symmetry organic scintillator systems

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Patrick L.

    2018-03-13

    An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based on the pulse shapes of the output signals.

  11. Designing an optimally proportional inorganic scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jai, E-mail: jai.singh@cdu.edu.au [School of Engineering and IT, B-Purple-12, Faculty of EHSE, Charles Darwin University, NT 0909 (Australia); Koblov, Alexander [School of Engineering and IT, B-Purple-12, Faculty of EHSE, Charles Darwin University, NT 0909 (Australia)

    2012-09-01

    The nonproportionality observed in the light yield of inorganic scintillators is studied theoretically as a function of the rates of bimolecular and Auger quenching processes occurring within the electron track initiated by a gamma- or X-ray photon incident on a scintillator. Assuming a cylindrical track, the influence of the track radius and concentration of excitations created within the track on the scintillator light yield is also studied. Analysing the calculated light yield a guideline for inventing an optimally proportional scintillator with optimal energy resolution is presented.

  12. Designing an optimally proportional inorganic scintillator

    International Nuclear Information System (INIS)

    Singh, Jai; Koblov, Alexander

    2012-01-01

    The nonproportionality observed in the light yield of inorganic scintillators is studied theoretically as a function of the rates of bimolecular and Auger quenching processes occurring within the electron track initiated by a gamma- or X-ray photon incident on a scintillator. Assuming a cylindrical track, the influence of the track radius and concentration of excitations created within the track on the scintillator light yield is also studied. Analysing the calculated light yield a guideline for inventing an optimally proportional scintillator with optimal energy resolution is presented.

  13. High-symmetry organic scintillator systems

    Science.gov (United States)

    Feng, Patrick L.

    2017-07-18

    An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based on the pulse shapes of the output signals.

  14. Some adsorption characteristics of polysterene base scintillators

    International Nuclear Information System (INIS)

    Seredenko, T.N.; Ehkkerman, V.M.; Solomonov, V.M.; Gen, N.S.

    1980-01-01

    It is necessary to account for the adsorption on the surface of a scintillator when measuring nuclide activity in solutions by submerging into these solutions plastic scintillators. Dependences of 144 Ce, 90 Y, 137 Cs adsorption on specific activities (α) and pH value of solution were investigated. It is shown that K-α ratio is described by the equation K=Casup(p), where K is the specific surface activity of the polystyrene scintillator. Values of C and p are presented for investigated nuclides. The criterion estimating the possibility for repeated usage of scintillator are considered

  15. Design of Fluorescent Compounds for Scintillation Detection

    Energy Technology Data Exchange (ETDEWEB)

    Pla-Dalmau, Anna [Northern Illinois U.

    1990-01-01

    Plastic scintillation detectors for high energy physics applications require the development of new fluorescent compounds to meet the demands set by the future generation of particle accelerators such as the Superconducting Supercollider (SSe). Plastic scintillators are commonly based on a polymer matrix doped with two fluorescent compounds: the primary dopant and the wavelength shifter. Their main characteristics are fast response time and high quantum efficiency. The exposure to larger radiation doses and demands for larger light output questions their survivability in the future experiments. A new type of plastic scintillator - intrinsic scintillator - has been suggested. It uses a single dopant as primary and wavelength shifter, and should be less susceptible to radiation damage....

  16. Waveshifters and Scintillators for Ionizing Radiation Detection

    International Nuclear Information System (INIS)

    Baumgaugh, B.; Bishop, J.; Karmgard, D.; Marchant, J.; McKenna, M.; Ruchti, R.; Vigneault, M.; Hernandez, L.; Hurlbut, C.

    2007-01-01

    Scintillation and waveshifter materials have been developed for the detection of ionizing radiation in an STTR program between Ludlum Measurements, Inc. and the University of Notre Dame. Several new waveshifter materials have been developed which are comparable in efficiency and faster in fluorescence decay than the standard material Y11 (K27) used in particle physics for several decades. Additionally, new scintillation materials useful for fiber tracking have been developed which have been compared to 3HF. Lastly, work was done on developing liquid scintillators and paint-on scintillators and waveshifters for high radiation environments

  17. High-symmetry organic scintillator systems

    Science.gov (United States)

    Feng, Patrick L.

    2018-02-06

    An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based on the pulse shapes of the output signals.

  18. Liquid scintillation: Sample preparation and counting atypical emissions

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Liquid scintillation sample preparation has the most published information but the least amount of definitive technical direction because the chemical and physical nature of the samples from biological investigations varies widely. This chapter discusses the following related topics: Aqueous Samples; Tissue Solubilizers; Absorption of 14 CO 2 ; Sample Combustion Methods; Heterogeneous Systems; Sample Preparation Problems (colored samples, chemiluminescence, photoluminescence, static electricity); Counting Various Types of Emitters; Counting Atypical Emissions. 2 refs., 2 figs

  19. BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET

    Science.gov (United States)

    Brunner, S. E.; Schaart, D. R.

    2017-06-01

    Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times (CRT) between 325 ps and 400 ps FWHM have recently been developed. Before the introduction of L(Y)SO:Ce, BGO was used in many PET systems. In addition to a lower price, BGO offers a superior attenuation coefficient and a higher photoelectric fraction than L(Y)SO:Ce. However, BGO is generally considered an inferior TOF-PET scintillator. In recent years, TOF-PET detectors based on the Cherenkov effect have been proposed. However, the low Cherenkov photon yield in the order of  ˜10 photons per event complicates energy discrimination-a severe disadvantage in clinical PET. The optical characteristics of BGO, in particular its high transparency down to 310 nm and its high refractive index of  ˜2.15, are expected to make it a good Cherenkov radiator. Here, we study the feasibility of combining event timing based on Cherenkov emission with energy discrimination based on scintillation in BGO, as a potential approach towards a cost-effective TOF-PET detector. Rise time measurements were performed using a time-correlated single photon counting (TCSPC) setup implemented on a digital photon counter (DPC) array, revealing a prompt luminescent component likely to be due to Cherenkov emission. Coincidence timing measurements were performed using BGO crystals with a cross-section of 3 mm  ×  3 mm and five different lengths between 3 mm and 20 mm, coupled to DPC arrays. Non-Gaussian coincidence spectra with a FWHM of 200 ps were obtained with the 27 mm3 BGO cubes, while FWHM values as good as 330 ps were achieved with the 20 mm long crystals. The FWHM value was found to improve with decreasing temperature, while the FWTM value showed the opposite trend.

  20. BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET.

    Science.gov (United States)

    Brunner, S E; Schaart, D R

    2017-06-07

    Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times (CRT) between 325 ps and 400 ps FWHM have recently been developed. Before the introduction of L(Y)SO:Ce, BGO was used in many PET systems. In addition to a lower price, BGO offers a superior attenuation coefficient and a higher photoelectric fraction than L(Y)SO:Ce. However, BGO is generally considered an inferior TOF-PET scintillator. In recent years, TOF-PET detectors based on the Cherenkov effect have been proposed. However, the low Cherenkov photon yield in the order of  ∼10 photons per event complicates energy discrimination-a severe disadvantage in clinical PET. The optical characteristics of BGO, in particular its high transparency down to 310 nm and its high refractive index of  ∼2.15, are expected to make it a good Cherenkov radiator. Here, we study the feasibility of combining event timing based on Cherenkov emission with energy discrimination based on scintillation in BGO, as a potential approach towards a cost-effective TOF-PET detector. Rise time measurements were performed using a time-correlated single photon counting (TCSPC) setup implemented on a digital photon counter (DPC) array, revealing a prompt luminescent component likely to be due to Cherenkov emission. Coincidence timing measurements were performed using BGO crystals with a cross-section of 3 mm  ×  3 mm and five different lengths between 3 mm and 20 mm, coupled to DPC arrays. Non-Gaussian coincidence spectra with a FWHM of 200 ps were obtained with the 27 mm 3 BGO cubes, while FWHM values as good as 330 ps were achieved with the 20 mm long crystals. The FWHM value was found to improve with decreasing temperature, while the FWTM value showed the opposite

  1. Basic performance of Mg co-doped new scintillator used for TOF-DOI-PET systems

    International Nuclear Information System (INIS)

    Kobayashi, Takahiro; Yamamoto, Seiichi; Okumura, Satoshi; Yeom, Jung Yeol; Kamada, Kei; Yoshikawa, Akira

    2017-01-01

    Phoswich depth-of-interaction (DOI) detectors utilizing multiple scintillators with different decay time are a useful device for developing a high spatial resolution, high sensitivity PET scanner. However, in order to apply pulse shape discrimination (PSD), there are not many combinations of scintillators for which phoswich technique can be implemented. Ce doped Gd_3Ga_3Al_2O_1_2 (GFAG) is a recently developed scintillator with a fast decay time. This scintillator is similar to Ce doped Gd_3Al_2Ga_3O_1_2 (GAGG), which is a promising scintillator for PET detector with high light yield. By stacking these scintillators, it may be possible to realize a high spatial resolution and high timing resolution phoswich DOI detector. Such phoswich DOI detector may be applied to time-of-flight (TOF) systems with high timing performance. Therefore, in this study, we tested the basic performance of the new scintillator –GFAG for use in a TOF phoswich detector. The measured decay time of a GFAG element of 2.9 mmx2.9 mmx10 mm in dimension, which was optically coupled to a photomultiplier tube (PMT), was faster (66 ns) than that of same sized GAGG (103 ns). The energy resolution of the GFAG element was 5.7% FWHM which was slightly worse than that of GAGG with 4.9% FWHM for 662 keV gamma photons without saturation correction. Then we assembled the GFAG and the GAGG crystals in the depth direction to form a 20 mm long phoswich element (GFAG/GAGG). By pulse shape analysis, the two types of scintillators were clearly resolved. Measured timing resolution of a pair of opposing GFAG/GAGG phoswich scintillator coupled to Silicon Photomultipliers (Si-PM) was good with coincidence resolving time of 466 ps FWHM. These results indicate that the GFAG combined with GAGG can be a candidate for TOF-DOI-PET systems.

  2. Low-latitude scintillation occurrences around the equatorial anomaly crest over Indonesia

    Directory of Open Access Journals (Sweden)

    P. Abadi

    2014-01-01

    Full Text Available We investigated low-latitude ionospheric scintillation in Indonesia using two GPS receivers installed at Bandung (107.6° E, 6.9° S; magnetic latitude 17.5° S and Pontianak (109.3° E, 0.02° S; magnetic latitude 8.9° S. This study aimed to characterise climatological and directional ionospheric scintillation occurrences, which are useful not only for the physics of ionospheric irregularities but also for practical use in GNSS (global navigation satellite system-based navigation. We used the deployed instrument's amplitude scintillation (S4 index data from 2009, 2010, and 2011; the yearly SSN (sunspot-smoothed numbers were 3.1, 16.5, and 55.9, respectively. In summary, (1 scintillation occurrences in the post-sunset period (18:00–01:00 LT during equinox months (plasma bubble season at the two sites can be ascribed to the plasma bubble; (2 using directional analyses of the two sites, we found that the distribution of scintillation occurrences is generally concentrated between the two sites, indicating the average location of the EIA (equatorial ionisation anomaly crest; (3 scintillation occurrence enhancements for the two sites in field-aligned directions are herein reported for the first time by ground-based observation in a low-latitude region; (4 distribution of scintillation occurrences at Pontianak are concentrated in the southern sky, especially in the southwest direction, which is very likely associated with the plasma bubble tilted westward with increasing latitude; and (5 scintillation occurrence in the post-midnight period in the non-plasma-bubble season is the most intriguing variable occurring between the two sites (i.e. post-midnight scintillations are observed more at Bandung than Pontianak. Most of the post-midnight scintillations observed at Bandung are concentrated in the northern sky, with low elevation angles. This might be due to the amplitude of irregularities in certain directions, which may be effectively enhanced by

  3. Advantages of GSO Scintillator in Imaging and Law Level Gamma-ray Spectroscopy

    CERN Document Server

    Sharaf, J

    2002-01-01

    The single GSO crystal is an excellent scintillation material featuring a high light yield and short decay time for gamma-ray detection. Its performance characteristics were investigated and directly compared to those of BGO. For this purpose, the two scintillators are cut into small crystals of approximately 4*4*10 mm sup 3 and mounted on a PMT. Energy resolution, detection efficiency and counting precision have been measured for various photon energies. In addition to this spectroscopic characterization, the imaging performance of GSO was studied using a scanning rig. The modulation transfer function was calculated and the spatial resolution evaluated by measurements of the detector's point spread function. It is shown that there exists some source intensity for which the two scintillators yield identical precision for identical count time. Below this intensity, the GSO is superior to the BGO detector. The presented properties of GSO suggest potential applications of this scintillator in gamma-ray spectrosc...

  4. A theoretical model evaluating the angular distribution of luminescence emission in X-ray scintillating screens

    International Nuclear Information System (INIS)

    Kandarakis, I.; Cavouras, D.; Nikolopoulos, D.; Episkopakis, A.; Kalivas, N.; Liaparinos, P.; Valais, I.; Kagadis, G.; Kourkoutas, K.; Sianoudis, I.; Dimitropoulos, N.; Nomicos, C.; Panayiotakis, G.

    2006-01-01

    The aim of this study was to examine the angular distribution of the light emitted from radiation-excited scintillators in medical imaging detectors. This distribution diverges from Lambert's cosine law and affects the light emission efficiency of scintillators, hence it also affects the dose burden to the patient. In the present study, the angular distribution was theoretically modeled and was used to fit experimental data on various scintillator materials. Results of calculations revealed that the angular distribution is more directional than that predicted by Lambert's law. Divergence from this law is more pronounced for high values of light attenuation coefficient and thick scintillator layers (screens). This type of divergence reduces light emission efficiency and hence it increases the incident X-ray flux required for a given level of image brightness

  5. Collimator changer for scintillation camera

    International Nuclear Information System (INIS)

    Jupa, E.C.; Meeder, R.L.; Richter, E.K.

    1976-01-01

    A collimator changing assembly mounted on the support structure of a scintillation camera is described. A vertical support column positioned proximate the detector support column with a plurality of support arms mounted thereon in a rotatable cantilevered manner at separate vertical positions. Each support arm is adapted to carry one of the plurality of collimators which are interchangeably mountable on the underside of the detector and to transport the collimator between a store position remote from the detector and a change position underneath said detector

  6. New shaper of scintillation signals

    International Nuclear Information System (INIS)

    Brovchenko, V.G.

    2001-01-01

    Summation of the exponential shape pulse (abrupt front, exponential fall-off) with the pulse, proportional to its integral (the integration time constant is equal to the exponent fall-off constant), results in the pulse, the apex whereof is horizontal (parallel to the base line). Such a pulse is suitable for registration through standard analog-to-digital converters of the consecutive binary approximation, The described scheme is accomplished for verification of the basic principle of the shaper action. The parameters of the scheme are approximated to those ones, necessary for processing scintillation signals NaI(Tl) [ru

  7. Scintillating fibre tracking neutron detector

    International Nuclear Information System (INIS)

    Karlsson, Joakim.

    1995-04-01

    A detector for measurements of collimated fluxes of neutrons in the energy range 2-20 MeV is proposed. It utilizes (n.p) elastic scattering in scintillating optical fibres placed in successive orthogonal layers perpendicular to the neutron flux. A test module has been designed, constructed and tested with respect to separation of neutron and gamma events. The pulse height measurements show the feasibility to discriminate between neutron, gamma and background events. Application to measurements of fusion neutrons is considered. 18 refs, 22 figs, 4 tabs

  8. Pulsar scintillation patterns and strangelets

    Energy Technology Data Exchange (ETDEWEB)

    Pérez-García, M. Ángeles, E-mail: mperezga@usal.es [Department of Fundamental Physics and IUFFyM, University of Salamanca, Plaza de la Merced s/n, 37008 Salamanca (Spain); Silk, Joseph, E-mail: silk@iap.fr [Institut d' Astrophysique, UMR 7095, CNRS, Université Pierre et Marie Curie, 98bis Blvd Arago, 75014 Paris (France); Department of Physics and Astronomy, Johns Hopkins University, Homewood Campus, Baltimore MD 21218 (United States); Beecroft Institute of Particle Astrophysics and Cosmology, Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Pen, Ue-Li, E-mail: pen@cita.utoronto.ca [Canadian Institute for Theoretical Astrophysics, University of Toronto, 0N M5S 3H8 (Canada)

    2013-12-18

    We propose that interstellar extreme scattering events, usually observed as pulsar scintillations, may be caused by a coherent agent rather than the usually assumed turbulence of H{sub 2} clouds. We find that the penetration of a flux of ionizing, positively charged strangelets or quark nuggets into a dense interstellar hydrogen cloud may produce ionization trails. Depending on the specific nature and energy of the incoming droplets, diffusive propagation or even capture in the cloud are possible. As a result, enhanced electron densities may form and constitute a lens-like scattering screen for radio pulsars and possibly for quasars.

  9. Large surface scintillators as base of impact point detectors and their application in Space Weather

    Science.gov (United States)

    Ayuso, Sindulfo; Medina, José; Gómez-Herrero, Raul; José Blanco, Juan; García-Tejedor, Ignacio; García-Población, Oscar; Díaz-Romeral, Gonzalo

    2016-04-01

    The use of a pile of two 100 cm x 100 cm x 5 cm BC-400 organic scintillators is proposed as ground-based cosmic ray detector able to provide directional information on the incident muons. The challenge is to get in real time the muon impact point on the scintillator and its arrival direction using as few Photomultiplier Tubes (PMTs) as possible. The instrument is based on the dependence of attenuation of light with the traversed distance in each scintillator. For the time being, four photomultiplier tubes gather the light through the lateral faces (100 cm x 5 cm) of the scintillator. Several experiments have already been carried out. The results show how data contain information about the muon trajectory through the scintillator. This information can be extracted using the pulse heights collected by the PMTs working in coincidence mode. Reliability and accuracy of results strongly depend on the number of PMTs used and mainly on their appropriate geometrical arrangement with regard to the scintillator. In order to determine the optimal position and the minimum number of PMTs required, a Montecarlo simulation code has been developed. Preliminary experimental and simulation results are presented and the potential of the system for space weather monitoring is discussed.

  10. Mounting LHCb hadron calorimeter scintillating tiles

    CERN Multimedia

    Maximilien Brice

    2004-01-01

    Scintillating tiles are carefully mounted in the hadronic calorimeter for the LHCb detector. These calorimeters measure the energy of particles that interact via the strong force, called hadrons. The detectors are made in a sandwich-like structure where these scintillator tiles are placed between metal sheets.

  11. Lower bounds on scintillation detector timing performance

    International Nuclear Information System (INIS)

    Clinthorne, N.H.; Rogers, W.L.; Hero, A.O. III.; Petrick, N.A.

    1990-01-01

    Fundamental method-independent limits on the timing performance of scintillation detectors are useful for identifying regimes in which either present timing methods are nearly optimal or where a considerable performance gain might be realized using better pulse processing techniques. Several types of lower bounds on mean-squared timing error (MSE) performance have been developed and applied to scintillation detectors. The simple Cramer-Rao (CR) bound can be useful in determining the limiting MSE for scintillators having a relatively high rate of photon problction such as BaF 2 and NaI(Tl); however, it tends to overestimate the achievalbe performance for scintillators with lower rates such as BGO. For this reason, alternative bounds have been developed using rate-distortion theory or by assuming that the conversion of energy to scintillation light must pass through excited states which have exponential lifetime densities. The bounds are functions of the mean scintillation pulse shape, the scintillation intensity, and photodetector characteristics; they are simple to evaluate and can be used to conveniently assess the limiting timing performance of scintillation detectors. (orig.)

  12. Scintillation device of X-ray detection

    International Nuclear Information System (INIS)

    Polack, F.; Bigler, E.

    1985-01-01

    The detection device comprises a screen made of microtubes transparent to the light emitted by a scintillator material in the microtube channels. The scintillator material optical index is greater than the microtube material index, so as to constitute optical fiber, with index rise, guiding the light toward the outside [fr

  13. Status of timing with plastic scintillation detectors

    International Nuclear Information System (INIS)

    Moszynski, M.; Bengtson, B.

    1979-01-01

    Timing properties of scintillators and photomultipliers as well as theoretical and experimental studies of time resolution of scintillation counters are reviewed. Predictions of the theory of the scintillation pulse generation processes are compared with the data on the light pulse shape from small samples, in which the light pulse shape depends only on the composition of the scintillator. For larger samples the influence of the light collection process and the self-absorption process on the light pulse shape are discussed. The data on rise times, fwhm's, decay times and light yield of several commercial scintillators used in timing are collected. The next part of the paper deals with the properties of photomultipliers. The sources of time uncertainties in photomultipliers as a spread of the initial velocity of photoelectrons, emission of photoelectrons under different angles and from different points at the photocathode, the time spread and the gain dispersion introduced by electron photomultiplier are reviewed. The experimental data on the time jitter, single electron response and photoelectron yield of some fast photomultipliers are collected. As the time resolution of the timing systems with scintillation counters depends also on time pick-off units, a short presentation of the timing methods is given. The discussion of timing theories is followed by a review of experimental studies of the time resolution of scintillation counters. The paper is ended by an analysis of prospects on further progress of the subnanosecond timing with scintillation counters. (Auth.)

  14. Current status of liquid scintillation counting

    International Nuclear Information System (INIS)

    Klingler, G.W.

    1981-01-01

    Scintillation counting of alpha particles has been used since the turn of the century. The advent of pulse shape discrimination has made this method of detection accurate and reliable. The history, concepts and development of scintillation counting and pulse shape discrimination are discussed. A brief look at the ongoing work in the consolidation of components now used for pulse shape discrimination is included

  15. Some possible improvements in scintillation calorimeters

    International Nuclear Information System (INIS)

    Lorenz, E.

    1985-03-01

    Two ideas for improvements of scintillation calorimeters will be presented: a) improved readout of scintillating, totally active electromagnetic calorimeters with combinations of silicon photodiodes and fluorescent panel collectors, b) use of time structure analysis on calorimetry, both for higher rate applications and improved resolution for hadron calorimeters. (orig.)

  16. Performance and characteristics of a new scintillator

    CERN Document Server

    Czirr, J B; MacGillivray, R R; Seddon, P J

    1999-01-01

    A new class of scintillators for neutron imaging, based upon lithium gadolinium borate, is described. These scintillators offer the ability to tailor their response to the neutron spectrum by varying the relative absorption of neutrons by the key constituents (lithium, gadolinium and boron). The isotopic compositions of each constituent can be varied in order to change the spectral response.

  17. Development of scintillation materials for PET scanners

    CERN Document Server

    Korzhik, Mikhail; Annenkov, Alexander N; Borissevitch, Andrei; Dossovitski, Alexei; Missevitch, Oleg; Lecoq, Paul

    2007-01-01

    The growing demand on PET methodology for a variety of applications ranging from clinical use to fundamental studies triggers research and development of PET scanners providing better spatial resolution and sensitivity. These efforts are primarily focused on the development of advanced PET detector solutions and on the developments of new scintillation materials as well. However Lu containing scintillation materials introduced in the last century such as LSO, LYSO, LuAP, LuYAP crystals still remain the best PET species in spite of the recent developments of bright, fast but relatively low density lanthanum bromide scintillators. At the same time Lu based materials have several drawbacks which are high temperature of crystallization and relatively high cost compared to alkali-halide scintillation materials. Here we describe recent results in the development of new scintillation materials for PET application.

  18. Detector construction for a scintillation camera

    International Nuclear Information System (INIS)

    Ashe, J.B.

    1977-01-01

    An improved transducer construction for a scintillation camera in which a light conducting element is equipped with a layer of moisture impervious material is described. A scintillation crystal is thereafter positioned in optical communication with the moisture impervious layer and the remaining surfaces of the scintillation crystal are encompassed by a moisture shield. Affixing the moisture impervious layer to the light conducting element prior to attachment of the scintillation crystal reduces the requirement for mechanical strength in the moisture impervious layer and thereby allows a layer of reduced thickness to be utilized. Preferably, photodetectors are also positioned in optical communication with the light conducting element prior to positioning the scintillation crystal in contact with the impervious layer. 13 claims, 4 figures

  19. Liquid mixtures for scintillation counters

    International Nuclear Information System (INIS)

    Kauffmann, J.M.

    1975-01-01

    Liquid scintillators contain emulsifiers or combinations of these which can be used over a wide temperature range for a multitude of aqueous samples. These emulsifiers are block-polymerides with a nonhygroscopic center part of the chain of oxypropylene combinations recieved by addition of propylene oxide to both hydroxyl groups of a propylene-glycol nucleus and both ends of the center part of the chain terminating in hygroscopic poly(oxyethylene) groups. The length of the nonhygroscopic center part of the chain varies from about 800 to 3,000 or 4,000 in molecular weight. The hygroscopic poly(oxyethylene) end groups have a controlled length constituting about 10 to 80wt.% of the finished molecule. The most useful members of this group of co-polymerides possess a length of their poly(oxypropylene) chains corresponding to a value of y of about 15 to 56 and a length of their poly(oxyethylene)chains corresponding to values of x and z between 1 and 35 . All known fluorines can be used. With the scintillators the radioimmunoassay can also be carried through. (DG/PB) [de

  20. Inorganic-organic rubbery scintillators

    CERN Document Server

    Gektin, A V; Pogorelova, N; Neicheva, S; Sysoeva, E; Gavrilyuk, V

    2002-01-01

    Spectral-kinetic luminescence properties of films, containing homogeneously dispersed scintillation particles of CsI, CsI:Tl, CsI:Na, and NaI:Tl in optically transparent organosiloxane matrix, are presented. Material is flexible and rubbery and in consequence the detectors of convenient shapes can be produced. It is found that luminescence spectra of the received films are identical whereas decay times are much shorter compared to the same ones of the corresponding single crystals. Layers with pure CsI demonstrate only the fast UV emission (307 nm, 10 ns) without blue microsecond afterglow typical for crystals. The films containing NaI:Tl are non-hygroscopic and preserve scintillation properties for a long time in humid atmosphere unlike single crystals. Organosiloxane layers with CsI:Tl particles provide high light output with good energy resolution for sup 5 sup 5 Fe, sup 1 sup 0 sup 9 Cd, sup 2 sup 4 sup 1 Am sources, and are capable of detecting both X-rays and alpha-, beta-particles.