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Sample records for direct photon-counting scintillation

  1. Screening Method of New Inorganic Scintillators for Photon Counting

    Science.gov (United States)

    Pritchard, Megan

    2004-10-01

    Inorganic scintillators play an important role in detection and visualization of ionizing radiation. A scintillator with both high light yield and fast response has yet to be found. These methods are useful in detector applications for homeland security and nuclear non-proliferation. New scintillators are necessary to improve radiation detectors for detection of fissile materials specifically when shielded. At ORNL, several new inorganic scintillators including various versions of ZnO, and SnO2 are being evaluated to determine light yield and decay times. Crystals are grown here, doped or painted with metals such as Al, Cd, Sn or Ga and measured. The photons emitted from a scintillator from a single incident alpha or neutron can be counted and graphed, allowing the luminosity and decay constants to be determined. The promising samples are also being evaluated for exact luminosity through spectroscopy.

  2. Screening Method of Inorganic Scintillators for Photon Counting

    Science.gov (United States)

    Pritchard, M.

    2004-10-01

    Inorganic scintillators play an important role in detection and visualization of ionizing radiation. A scintillator with both high light yield and fast response has yet to be found. These methods are useful in detector applications for homeland security and nuclear non-proliferation. New scintillators are necessary to improve radiation detectors for detection of fissile materials specifically when shielded. At ORNL, several new inorganic scintillators including various versions of ZnO, and SnO2 are being evaluated to determine light yield and decay times. Crystals are grown here, doped or painted with metals such as Al, Cd, Sn or Ga and measured. The photons emitted from a scintillator from a single incident alpha or neutron can be counted and graphed, allowing the luminosity and decay constants to be determined

  3. Characterizing time decay of bibenzyl scintillator using time correlated single photon counting

    Energy Technology Data Exchange (ETDEWEB)

    Hatarik, R.; Bernstein, L. A.; Caggiano, J. A.; Carman, M. L.; Schneider, D. H. G.; Zaitseva, N. P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Wiedeking, M. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); iThemba LABS, P.O. Box 722, 7129 Somerset West (South Africa)

    2012-10-15

    The time decay of several scintillation materials has been measured using the time correlated single photon counting method and a new organic crystal with a highly suppressed delayed light has been identified. Results comparing the light decay of the bibenzyl crystal with a xylene based detector, which is currently installed at National Ignition Facility will be presented.

  4. Scintillation induced response in passively-quenched Si-based single photon counting avalanche diode arrays.

    Science.gov (United States)

    Spanoudaki, Virginia Ch; Levin, Craig S

    2011-01-17

    An optical electrical model which studies the response of Si-based single photon counting arrays, specifically silicon photomultipliers (SiPMs), to scintillation light has been developed and validated with analytically derived and experimental data. The scintillator-photodetector response in terms of relative pulse height, 10%-90% rise/decay times to light stimuli of different rise times (ranging from 0.1 to 5 ns) and decay times (ranging from 1 to 50 ns), as well as for different decay times of the photodetector are compared in theory and simulation. A measured detector response is used as a reference to further validate the model and the results show a mean deviation of simulated over measured values of 1%.

  5. 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.

  6. Comparison of Image Uniformity with Photon Counting and Conventional Scintillation Single-Photon Emission Computed Tomography System: A Monte Carlo Simulation Study

    Directory of Open Access Journals (Sweden)

    Ho Chul Kim

    2017-06-01

    Full Text Available 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 99mTc 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.

  7. 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.

  8. Direct charge sharing observation in single-photon-counting pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Pellegrini, G. [Centro Nacional de Microelectronica, IMB-CNM (CSIC), Barcelona 08193 (Spain)]. E-mail: Giulio.Pellegrini@cnm.es; Maiorino, M. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Blanchot, G. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Chmeissani, M. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Garcia, J. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Lozano, M. [Centro Nacional de Microelectronica, IMB-CNM (CSIC), Barcelona 08193 (Spain); Martinez, R. [Centro Nacional de Microelectronica, IMB-CNM (CSIC), Barcelona 08193 (Spain); Puigdengoles, C. [IFAE - Institut de Fisica d' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Ullan, M. [Centro Nacional de Microelectronica, IMB-CNM (CSIC), Barcelona 08193 (Spain)

    2007-04-01

    In photon-counting imaging devices, charge sharing can limit the detector spatial resolution and contrast, as multiple counts can be induced in adjacent pixels as a result of the spread of the charge cloud generated from a single X-ray photon of high energy in the detector bulk. Although debated for a long time, the full impact of charge sharing has not been completely assessed. In this work, the importance of charge sharing in pixellated CdTe and silicon detectors is studied by exposing imaging devices to different low activity sources. These devices are made of Si and CdTe pixel detector bump-bonded to Medipix2 single-photon-counting chips with a 55 {mu}m pixel pitch. We will show how charge sharing affects the spatial detector resolution depending on incident particle type (alpha, beta and gamma), detector bias voltage and read-out chip threshold. This study will give an insight on the impact on the design and operation of pixel detectors coupled to photon-counting devices for imaging applications.

  9. Direct charge sharing observation in single-photon-counting pixel detector

    Science.gov (United States)

    Pellegrini, G.; Maiorino, M.; Blanchot, G.; Chmeissani, M.; Garcia, J.; Lozano, M.; Martinez, R.; Puigdengoles, C.; Ullan, M.

    2007-04-01

    In photon-counting imaging devices, charge sharing can limit the detector spatial resolution and contrast, as multiple counts can be induced in adjacent pixels as a result of the spread of the charge cloud generated from a single X-ray photon of high energy in the detector bulk. Although debated for a long time, the full impact of charge sharing has not been completely assessed. In this work, the importance of charge sharing in pixellated CdTe and silicon detectors is studied by exposing imaging devices to different low activity sources. These devices are made of Si and CdTe pixel detector bump-bonded to Medipix2 single-photon-counting chips with a 55 μm pixel pitch. We will show how charge sharing affects the spatial detector resolution depending on incident particle type (alpha, beta and gamma), detector bias voltage and read-out chip threshold. This study will give an insight on the impact on the design and operation of pixel detectors coupled to photon-counting devices for imaging applications.

  10. Photon counting digital holography

    Science.gov (United States)

    Demoli, Nazif; Skenderović, Hrvoje; Stipčević, Mario; Pavičić, Mladen

    2016-05-01

    Digital holography uses electronic sensors for hologram recording and numerical method for hologram reconstruction enabling thus the development of advanced holography applications. However, in some cases, the useful information is concealed in a very wide dynamic range of illumination intensities and successful recording requires an appropriate dynamic range of the sensor. An effective solution to this problem is the use of a photon-counting detector. Such detectors possess counting rates of the order of tens to hundreds of millions counts per second, but conditions of recording holograms have to be investigated in greater detail. Here, we summarize our main findings on this problem. First, conditions for optimum recording of digital holograms for detecting a signal significantly below detector's noise are analyzed in terms of the most important holographic measures. Second, for time-averaged digital holograms, optimum recordings were investigated for exposures shorter than the vibration cycle. In both cases, these conditions are studied by simulations and experiments.

  11. Photon counting detector for the personal radiography inspection system "SIBSCAN"

    Science.gov (United States)

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

    2017-02-01

    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.

  12. Photon counts modulation in optical time domain reflectometry

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Bo; Wang Jing-Jing; Zhang Guo-Feng; Xiao Lian-Tuan; Jia Suo-Tang

    2011-01-01

    The quantum fluctuation of photon counting limits the field application of optical time domain reflection. A method of photon counts modulation optics time domain reflection with single photon detection at 1.55 un is presented. The influence of quantum fluctuation can be effectively controlled by demodulation technology since quantum fluctuation shows a uniform distribution in the frequency domain. Combined with the changing of the integration time of the lock-in amplifier, the signal to noise ratio is significantly enhanced. Accordingly the signal to noise improvement ratio reaches 31.7 dB compared with the direct photon counting measurement.

  13. Photon counting compressive depth mapping

    CERN Document Server

    Howland, Gregory A; Ware, Matthew R; Howell, John C

    2013-01-01

    We demonstrate a compressed sensing, photon counting lidar system based on the single-pixel camera. Our technique recovers both depth and intensity maps from a single under-sampled set of incoherent, linear projections of a scene of interest at ultra-low light levels around 0.5 picowatts. Only two-dimensional reconstructions are required to image a three-dimensional scene. We demonstrate intensity imaging and depth mapping at 256 x 256 pixel transverse resolution with acquisition times as short as 3 seconds. We also show novelty filtering, reconstructing only the difference between two instances of a scene. Finally, we acquire 32 x 32 pixel real-time video for three-dimensional object tracking at 14 frames-per-second.

  14. Calibrating photon counts from a single image

    CERN Document Server

    Heintzmann, Rainer; Nieuwenhuizen, Robert P J; Lidke, Keith A; Rieger, Bernd

    2016-01-01

    Most image capturing devices do not directly report the number of detected photons, but a value proportional to the photoelectron charge produced in a photomultiplier tube or collected in a camera pixel. In order to establish the photon count, the gain of the device must be measured, typically by recording tens of calibration images and exploiting the linear relationship between mean intensity and its variance [vanVliet1998]. Here we propose and evaluate a method that obtains the gain from a single acquired image by quantifying out-of-band information. As noise is not limited to the cut-off frequency of the optical transfer function (OTF), estimation of the out-of-band energy relative to the total energy enables computation of the gain. We show on simulation and experimental data that this much simpler procedure, which can be retroactively applied to any image, is comparable in precision to traditional gain calibration procedures.

  15. Photon-counting spaceborne altimeter simulator

    Science.gov (United States)

    Blazej, Josef

    2004-11-01

    We are presenting of a photon counting laser altimeter simulator. The simulator is designed to be a theoretical and numerical complement for a Technology Demonstrator of the space born laser altimeter for planetary studies built on our university. The European Space Agency has nominated the photon counting altimeter as one of the attractive devices for planetary research. The device should provide altimetry in the range 400 to 1400 km with one meter range resolution under rough conditions - Sun illumination, radiation, etc. The general altimeter concept expects the photon counting principle laser radar. According to this concept, the simulator is based on photon counting radar simulation, which has been enhanced to handle planetary surface roughness, vertical terrain profile and its reflectivity. The simulator is useful complement for any photon counting altimeter both for altimeter design and for measured data analysis. Our simulator enables to model the orbital motion, range, terrain profile, reflectivity, and their influence on the over all energy budget and the ultimate signal to noise ratio acceptable for the altimetry. The simulator can be adopted for various air or space born application.

  16. Comparison of single-photon counting and charge-integrating detectors for X-ray high-resolution imaging of small biological objects

    Science.gov (United States)

    Frallicciardi, Paola Maria; Jakubek, Jan; Vavrik, Daniel; Dammer, Jiri

    2009-08-01

    This work presents a direct comparison of two pixel detectors: a charge-integrating flat panel imager coupled to a CsI:Tl scintillator and a hybrid silicon detector of Medipix2 type, working in a single-photon counting mode. The comparison concerns image quality in terms of system-spatial resolution, signal-to-noise ratio and contrast in imaging of small biological objects. It will be shown that, at photon energies below 40 keV and for low attenuating biological objects, single-photon counting detectors are more appropriate for small-animal imaging than flat panel devices right due to better spatial resolution, signal-to-noise ratio and contrast.

  17. 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.

  18. Musculoskeletal imaging with a prototype photon-counting detector

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, M.; Uffmann, M.; Kainberger, F. [Medical University of Vienna, Department of Radiology, Vienna (Austria); Homolka, P. [Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Vienna (Austria); Chmeissani, M. [Institute for High Energy Physics, Medigal Imaging, Barcelona (Spain); Pretterklieber, M. [Medical University of Vienna, Center for Anatomy and Cell Biology, Vienna (Austria)

    2012-01-15

    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 x 256 pixels with a pixel pitch of 55 {mu}m. A monolithic image of 11.2 cm x 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 {mu}Gy) 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 {mu}Gy, 6.70 at 12 {mu}Gy, 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. (orig.)

  19. High resolution cross strip anodes for photon counting detectors

    Science.gov (United States)

    Siegmund, O. H. W.; Tremsin, A. S.; Vallerga, J. V.; Abiad, R.; Hull, J.

    2003-05-01

    A new photon counting, imaging readout for microchannel plate sensors, the cross strip (XS) anode, has been investigated. Charge centroiding of signals detected on two orthogonal layers of sense strip sets are used to derive photon locations. The XS anode spatial resolution (<3 μm FWHM) exceeds the spatial resolution of most direct charge sensing anodes, and does so at low gain (<2×10 6). The image linearity and fidelity are high enough to resolve and map 7 μm MCP pores, offering new possibilities for astronomical and other applications.

  20. Characterization of APDs for single photon counting

    Energy Technology Data Exchange (ETDEWEB)

    Buglak, Wladimir; Hannen, Volker; Joehren, Raphael; Surholt, Martin; Vollbrecht, Jonas; Weinheimer, Christian [Muenster Univ. (Germany). Inst. fuer Kernphysik; Noertershaeuser, Wilfried [Mainz Univ. (Germany). Inst. fuer Kernchemie; GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Sanchez, Rodolfo [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany)

    2013-07-01

    For the SPECTRAP experiment at GSI, Germany, a detector system with single-photon counting capability operating in the wavelength region from 300 nm up to 1100 nm has been developed at the University of Muenster. The detector system utilises a silicon avalanche photo diode (APD) cooled to liquid nitrogen temperatures and operated near the breakdown voltage to obtain high gain values. While the current setup uses a 2 x 2 mm{sup 2} APD (type RMD S0223), it would be advantageous to have a larger active area for easier adjustment of the experiment optics. On the other hand a larger active area is accompanied by increased thermal noise which might harm the photon counting performance of the device. The characterization of a 8 x 8 mm{sup 2} APD (RMD S0814) is the subject of this poster. Furthermore a signal analysis software was developed to supress noise signals, e.g. caused by microphonic effects. The software processes signal waveforms recorded by a Flash ADC and should allow for a lower trigger threshold and thus higher detection efficiency.

  1. 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

  2. Photon counting techniques with silicon avalanche photodiodes.

    Science.gov (United States)

    Dautet, H; Deschamps, P; Dion, B; Macgregor, A D; Macsween, D; McIntyre, R J; Trottier, C; Webb, P P

    1993-07-20

    The properties of avalanche photodiodes and associated electronics required for photon counting in the Geiger and the sub-Geiger modes are reviewed. When the Geiger mode is used, there are significant improvements reported in overall photon detection efficiencies (approaching 70% at 633 nm), and a timing jitter (under 200 ps) is achieved with passive quenching at high overvoltages (20-30 V). The results obtained by using an active-mode fast quench circuit capable of switching overvoltages as high as 15 V (giving photon detection efficiencies in the 50% range) with a dead time of less than 50 ns are reported. Larger diodes (up to 1 mm in diameter) that are usable in the Geiger mode and that have quantum efficiencies over 80% in the 500-800-nm range are also reported.

  3. Microtomography with photon counting detectors: improving the quality of tomographic reconstruction by voxel-space oversampling

    Science.gov (United States)

    Dudak, J.; Zemlicka, J.; Karch, J.; Hermanova, Z.; Kvacek, J.; Krejci, F.

    2017-01-01

    Photon counting detectors Timepix are known for their unique properties enabling X-ray imaging with extremely high contrast-to-noise ratio. Their applicability has been recently further improved since a dedicated technique for assembling large area Timepix detector arrays was introduced. Despite the fact that the sensitive area of Timepix detectors has been significantly increased, the pixel pitch is kept unchanged (55 microns). This value is much larger compared to widely used and popular X-ray imaging cameras utilizing scintillation crystals and CCD-based read-out. On the other hand, photon counting detectors provide steeper point-spread function. Therefore, with given effective pixel size of an acquired radiography, Timepix detectors provide higher spatial resolution than X-ray cameras with scintillation-based devices unless the image is affected by penumbral blur. In this paper we take an advance of steep PSF of photon counting detectors and test the possibility to improve the quality of computed tomography reconstruction using finer sampling of reconstructed voxel space. The achieved results are presented in comparison with data acquired under the same conditions using a commercially available state-of-the-art CCD X-ray camera.

  4. Feasibility of Amorphous Selenium Based Photon Counting Detectors for Digital Breast Tomosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J.; O' Connor, P.; Lehnert, J., De Geronimo, G., Dolazza, E., Tousignant, O., Laperriere, L., Greenspan, J., Zhao, W.

    2009-02-27

    Amorphous selenium (a-Se) has been incorporated successfully in direct conversion flat panel x-ray detectors, and has demonstrated superior image quality in screening mammography and digital breast tomosynthesis (DBT) under energy integration mode. The present work explores the potential of a-Se for photon counting detectors in DBT. We investigated major factors contributing to the variation in the charge collected by a pixel upon absorption of each x-ray photon. These factors included x-ray photon interaction, detector geometry, charge transport, and the pulse shaping and noise properties of the photon counting readout circuit. Experimental measurements were performed on a linear array test structure constructed by evaporating an a-Se layer onto an array of 100 {mu}m pitch strip electrodes, which are connected to a 32 channel low noise photon counting integrated circuit. The measured pulse height spectrum (PHS) under polychromatic xray exposure was interpreted quantitatively using the factors identified. Based on the understanding of a-Se photon counting performance, design parameters were proposed for a 2D detector with high quantum efficiency and count rate that could meet the requirements of photon counting detector for DBT.

  5. Energy response calibration of photon-counting detectors using x-ray fluorescence: a feasibility study.

    Science.gov (United States)

    Cho, H-M; Ding, H; Ziemer, B P; Molloi, S

    2014-12-07

    Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using x-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for x-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm(2) in detection area. The angular dependence of x-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded x-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of x-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of x-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic x-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the x-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory.

  6. 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...

  7. 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

  8. High Count Rate Single Photon Counting Detector Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An optical communications receiver requires efficient and high-rate photon-counting capability so that the information from every photon, received at the aperture,...

  9. 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.

  10. 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.

  11. Performance limits of a single photon counting pixel system

    Energy Technology Data Exchange (ETDEWEB)

    Chmeissani, M.; Mikulec, B. E-mail: bettina.mikulec@cern.ch

    2001-03-11

    X-ray imaging using hybrid pixel detectors in single photon counting mode is a relatively recent and exciting development. The photon counting mode implies that each pixel has a threshold in energy above which a hit is recorded. Sharing of charge between adjacent pixels would therefore lead to a loss of registered hits and for medical imaging applications to a higher patient dose. This explains why the demand for high spatial resolution and consequently small pixel sizes (<100 {mu}m) motivates the Medipix2 collaboration to study the effects of charge sharing between pixels on system performance. Two different simulation codes are used to simulate the energy loss inside the detector and the charge transport towards the pixel electrodes. The largest contribution to the lateral spreading of charge comes from diffusion and can result in a considerable loss of detection efficiency in photon counting systems for small pixel sizes.

  12. Correction of ultraviolet single photon counting image distortion

    Institute of Scientific and Technical Information of China (English)

    Xinghua Zhang; Baosheng Zhao; Zhenhua Miao; Wei Li; Xiangping Zhu; Yong'an Liu; Wei Zou

    2008-01-01

    Single photon counting imaging technology has been widely used in space environment detection, astronomy observation, nuclear physics, and ultraweak bioluminescence. However, the distortion of the single photon counting image will badly affect the measurement results. Therefore, the correction of distortion for single photon counting image is very significant. Ultraviolet single photon imaging system with wedge and strip anode is introduced and the influence factor leading to image distortion is analyzed. To correct original distorted image, three different image correction methods, namely, the physical correction, the global correction, and the local correction, are applied. In addition, two parameters, i.e, the position index and the linearity index, are defined to evaluate the performance of the three methods. The results suggest that the correction methods can improve the quality of the initial image without losing gray information of each counting light spot. And the local correction can provide the best visual inspections and performance evaluation among the three methods.

  13. 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...

  14. Photon counting modules using RCA silicon avalanche photodiodes

    Science.gov (United States)

    Lightstone, Alexander W.; Macgregor, Andrew D.; Macsween, Darlene E.; Mcintyre, Robert J.; Trottier, Claude; Webb, Paul P.

    1989-01-01

    Avalanche photodiodes (APD) are excellent small area, solid state detectors for photon counting. Performance possibilities include: photon detection efficiency in excess of 50 percent; wavelength response from 400 to 1000 nm; count rate to 10 (exp 7) counts per sec; afterpulsing at negligible levels; timing resolution better than 1 ns. Unfortunately, these performance levels are not simultaneously available in a single detector amplifier configuration. By considering theoretical performance predictions and previous and new measurements of APD performance, the anticipated performance of a range of proposed APD-based photon counting modules is derived.

  15. Negative Avalanche Feedback Detectors for Photon-Counting Optical Communications

    Science.gov (United States)

    Farr, William H.

    2009-01-01

    Negative Avalanche Feedback photon counting detectors with near-infrared spectral sensitivity offer an alternative to conventional Geiger mode avalanche photodiode or phototube detectors for free space communications links at 1 and 1.55 microns. These devices demonstrate linear mode photon counting without requiring any external reset circuitry and may even be operated at room temperature. We have now characterized the detection efficiency, dark count rate, after-pulsing, and single photon jitter for three variants of this new detector class, as well as operated these uniquely simple to use devices in actual photon starved free space optical communications links.

  16. Negative Avalanche Feedback Detectors for Photon-Counting Optical Communications

    Science.gov (United States)

    Farr, William H.

    2009-01-01

    Negative Avalanche Feedback photon counting detectors with near-infrared spectral sensitivity offer an alternative to conventional Geiger mode avalanche photodiode or phototube detectors for free space communications links at 1 and 1.55 microns. These devices demonstrate linear mode photon counting without requiring any external reset circuitry and may even be operated at room temperature. We have now characterized the detection efficiency, dark count rate, after-pulsing, and single photon jitter for three variants of this new detector class, as well as operated these uniquely simple to use devices in actual photon starved free space optical communications links.

  17. 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...

  18. Multimode model for projective photon-counting measurements

    DEFF Research Database (Denmark)

    Tualle-Brouri, Rosa; Ourjoumtsev, Alexei; Dantan, Aurélien

    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...

  19. Towards a Graphene-Based Low Intensity Photon Counting Photodetector.

    Science.gov (United States)

    Williams, Jamie O D; Alexander-Webber, Jack A; Lapington, Jon S; Roy, Mervyn; Hutchinson, Ian B; Sagade, Abhay A; Martin, Marie-Blandine; Braeuninger-Weimer, Philipp; Cabrero-Vilatela, Andrea; Wang, Ruizhi; De Luca, Andrea; Udrea, Florin; Hofmann, Stephan

    2016-08-23

    Graphene is a highly promising material in the development of new photodetector technologies, in particular due its tunable optoelectronic properties, high mobilities and fast relaxation times coupled to its atomic thinness and other unique electrical, thermal and mechanical properties. Optoelectronic applications and graphene-based photodetector technology are still in their infancy, but with a range of device integration and manufacturing approaches emerging this field is progressing quickly. In this review we explore the potential of graphene in the context of existing single photon counting technologies by comparing their performance to simulations of graphene-based single photon counting and low photon intensity photodetection technologies operating in the visible, terahertz and X-ray energy regimes. We highlight the theoretical predictions and current graphene manufacturing processes for these detectors. We show initial experimental implementations and discuss the key challenges and next steps in the development of these technologies.

  20. Towards a Graphene-Based Low Intensity Photon Counting Photodetector

    Directory of Open Access Journals (Sweden)

    Jamie O. D. Williams

    2016-08-01

    Full Text Available Graphene is a highly promising material in the development of new photodetector technologies, in particular due its tunable optoelectronic properties, high mobilities and fast relaxation times coupled to its atomic thinness and other unique electrical, thermal and mechanical properties. Optoelectronic applications and graphene-based photodetector technology are still in their infancy, but with a range of device integration and manufacturing approaches emerging this field is progressing quickly. In this review we explore the potential of graphene in the context of existing single photon counting technologies by comparing their performance to simulations of graphene-based single photon counting and low photon intensity photodetection technologies operating in the visible, terahertz and X-ray energy regimes. We highlight the theoretical predictions and current graphene manufacturing processes for these detectors. We show initial experimental implementations and discuss the key challenges and next steps in the development of these technologies.

  1. Nano-optomechanical measurement in the photon counting regime

    CERN Document Server

    de Lépinay, Laure Mercier; Rohr, Sven; Gloppe, Arnaud; Kuhn, Aurélien; Verlot, Pierre; Dupont-Ferrier, Eva; Besga, Benjamin; Arcizet, Olivier

    2015-01-01

    Optically measuring in the photon counting regime is a recurrent challenge in modern physics and a guarantee to develop weakly invasive probes. Here we investigate this idea on a hybrid nano-optomechanical system composed of a nanowire hybridized to a single Nitrogen-Vacancy (NV) defect. The vibrations of the nanoresonator grant a spatial degree of freedom to the quantum emitter and the photon emission event can now vary in space and time. We investigate how the nanomotion is encoded on the detected photon statistics and explore their spatio-temporal correlation properties. This allows a quantitative measurement of the vibrations of the nanomechanical oscillator at unprecedentedly low light intensities in the photon counting regime when less than one photon is detected per oscillation period, where standard detectors are dark-noise-limited. These results have implications for probing weakly interacting nanoresonators, for low temperature experiments and for investigating single moving markers.

  2. Probing the Conformations of Single Molecule via Photon Counting Statistics

    CERN Document Server

    Peng, Yonggang; Yang, Chuanlu; Zheng, Yujun

    2014-01-01

    We suggest an approach to detect the conformation of single molecule by using the photon counting statistics. The generalized Smoluchoswki equation is employed to describe the dynamical process of conformational change of single molecule. The resonant trajectories of the emission photon numbers $$ and the Mandel's $Q$ parameter, in the space of conformational coordinates $\\bm{\\mathcal{X}}$ and frequency $\\omega_L$ of external field ($\\bm{\\mathcal{X}}-\\omega_L$ space), can be used to rebuild the conformation of the single molecule. As an example, we consider Thioflavin T molecule. It demonstrates that the results of conformations extracted by employing the photon counting statistics is excellent agreement with the results of {\\it ab initio} computation.

  3. Optical phase estimation via coherent state and displaced photon counting

    CERN Document Server

    Izumi, Shuro; Wakui, Kentaro; Fujiwara, Mikio; Ema, Kazuhiro; Sasaki, Masahide

    2016-01-01

    We consider the phase sensing via weak optical coherent state at quantum limit precision. A new detection scheme for the phase estimation is proposed which is inspired by the suboptimal quantum measurement in coherent optical communication. We theoretically analyze a performance of our detection scheme, which we call the displaced-photon counting, for phase sensing in terms of the Fisher information and show that the displaced-photon counting outperforms the static homodyne and heterodyne detections in wide range of the target phase. The proof-of-principle experiment is performed with linear optics and a superconducting nanowire single photon detector. The result shows that our scheme overcomes the limit of the ideal homodyne measurement even under practical imperfections.

  4. Optical encryption using photon-counting polarimetric imaging.

    Science.gov (United States)

    Maluenda, David; Carnicer, Artur; Martínez-Herrero, Rosario; Juvells, Ignasi; Javidi, Bahram

    2015-01-26

    We present a polarimetric-based optical encoder for image encryption and verification. A system for generating random polarized vector keys based on a Mach-Zehnder configuration combined with translucent liquid crystal displays in each path of the interferometer is developed. Polarization information of the encrypted signal is retrieved by taking advantage of the information provided by the Stokes parameters. Moreover, photon-counting model is used in the encryption process which provides data sparseness and nonlinear transformation to enhance security. An authorized user with access to the polarization keys and the optical design variables can retrieve and validate the photon-counting plain-text. Optical experimental results demonstrate the feasibility of the encryption method.

  5. Photon-counting techniques with silicon avalanche photodiodes

    Science.gov (United States)

    Dautet, Henri; Deschamps, P.; Dion, Bruno; MacGregor, Andrew D.; MacSween, D.; McIntyre, Robert J.; Trottier, C.; Webb, Paul P.

    1993-05-01

    Silicon avalanche photodiodes (APD) have been used for photon counting for a number of years. This paper reviews their properties and the associated electronics required for photon counting in the Geiger mode. Significant improvements are reported in overall photon detection efficiencies (approaching 75% at 633 nm), and timing jitter (under 200 ps) achieved at high over-voltages (20 - 30 V). Results obtained using an active-mode fast quench circuit capable of switching over-voltages as high as 20 V (giving photon detection efficiencies in the 50% range), are reported with a dead-time of less than 50 ns. Larger diodes (up to 1 mm diameter), usable in the Geiger mode, which have quantum efficiencies over 80% in the 500 - 800 nm range also are reported.

  6. High quantum efficiency S-20 photocathodes for photon counting applications

    CERN Document Server

    Orlov, Dmitry A; Pinto, Serge Duarte; Glazenborg, Rene; Kernen, Emilie

    2016-01-01

    Based on conventional S-20 processes, a new series of high quantum efficiency (QE) photocathodes has been developed that can be specifically tuned for use in the ultraviolet, blue or green regions of the spectrum. The QE values exceed 30% at maximum response, and the dark count rate is found to be as low as 30 Hz/cm2 at room temperature. This combination of properties along with a fast temporal response makes these photocathodes ideal for application in photon counting detectors.

  7. Experimental reconstruction of photon statistics without photon counting.

    Science.gov (United States)

    Zambra, Guido; Andreoni, Alessandra; Bondani, Maria; Gramegna, Marco; Genovese, Marco; Brida, Giorgio; Rossi, Andrea; Paris, Matteo G A

    2005-08-05

    Experimental reconstructions of photon number distributions of both continuous-wave and pulsed light beams are reported. Our scheme is based on on/off avalanche photo-detection assisted by maximum-likelihood estimation and does not involve photon counting. Reconstructions of the distribution for both semiclassical and quantum states of light are reported for single-mode as well as for multi-mode beams.

  8. 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.

  9. Performance limits of a single photon counting pixel system

    Science.gov (United States)

    Chmeissani, M.; Mikulec, B.

    2001-03-01

    X-ray imaging using hybrid pixel detectors in single photon counting mode is a relatively recent and exciting development. The photon counting mode implies that each pixel has a threshold in energy above which a hit is recorded. Sharing of charge between adjacent pixels would therefore lead to a loss of registered hits and for medical imaging applications to a higher patient dose. This explains why the demand for high spatial resolution and consequently small pixel sizes (<100 μm) motivates the Medipix2 collaboration to study the effects of charge sharing between pixels on system performance. Two different simulation codes are used to simulate the energy loss inside the detector and the charge transport towards the pixel electrodes. The largest contribution to the lateral spreading of charge comes from diffusion and can result in a considerable loss of detection efficiency in photon counting systems for small pixel sizes. The Medipix2 collaboration consists of groups from Barcelona, Cagliari, CEA/Leti DEIN, CERN, Freiburg, Glasgow, Mitthögskolan, Napoli, NIKHEF, MRC lab Cambridge, Pisa, Prague and Sassari.

  10. Avalanche photodiode photon counting receivers for space-borne lidars

    Science.gov (United States)

    Sun, Xiaoli; Davidson, Frederic M.

    1991-01-01

    Avalanche photodiodes (APD) are studied for uses as photon counting detectors in spaceborne lidars. Non-breakdown APD photon counters, in which the APD's are biased below the breakdown point, are shown to outperform: (1) conventional APD photon counters biased above the breakdown point; (2) conventional APD photon counters biased above the breakdown point; and (3) APD's in analog mode when the received optical signal is extremely weak. Non-breakdown APD photon counters were shown experimentally to achieve an effective photon counting quantum efficiency of 5.0 percent at lambda = 820 nm with a dead time of 15 ns and a dark count rate of 7000/s which agreed with the theoretically predicted values. The interarrival times of the counts followed an exponential distribution and the counting statistics appeared to follow a Poisson distribution with no after pulsing. It is predicted that the effective photon counting quantum efficiency can be improved to 18.7 percent at lambda = 820 nm and 1.46 percent at lambda = 1060 nm with a dead time of a few nanoseconds by using more advanced commercially available electronic components.

  11. Investigation of the LabPET™ detector and electronics for photon-counting CT imaging

    Science.gov (United States)

    Bérard, Philippe; Riendeau, Joel; Pepin, Catherine M.; Rouleau, Daniel; Cadorette, Jules; Fontaine, Réjean; Lecomte, Roger

    2007-02-01

    The development of new molecular probes targeting receptors with high specificity in selected cells and tissues highlights the importance of obtaining the anatomical context in Positron Emission Tomography (PET) imaging. This can be achieved using another imaging modality, such as X-ray Computed Tomography (CT) or Magnetic Resonance Imaging (MRI), but the anatomic and molecular images obtained sequentially with different scanners must subsequently be co-registered and are subjected to motion artifacts. Conventional CT imaging also contributes a significant dose, which may compromise the benefits of longitudinal molecular imaging studies in the same subject. To overcome these difficulties, we have investigated the use of the LabPET™ detector and electronics as a multi-modal detection system. Based on fast light emitting inorganic scintillators individually coupled to avalanche photodiodes and parallel, low-noise, fast digital processing electronics, the proposed detector front-end is suitable for coincidence detection of annihilation radiation (511 keV) in PET and for ultra-fast low-energy X-ray photon counting in CT. This combined detection system enables concurrent PET/CT imaging while potentially achieving superior image contrast sensitivity for a given dose in CT photon-counting mode. Anatomical images with millimeter spatial resolution and sufficient tissue contrast for anatomical localization in small animals have been obtained with doses in the mGy range. The CT performance for dual-modality imaging of small animals was analyzed in terms of spatial resolution, noise and image contrast sensitivity as a function of dose.

  12. High quantum efficiency S-20 photocathodes in photon counting detectors

    Science.gov (United States)

    Orlov, D. A.; DeFazio, J.; Duarte Pinto, S.; Glazenborg, R.; Kernen, E.

    2016-04-01

    Based on conventional S-20 processes, a new series of high quantum efficiency (QE) photocathodes has been developed that can be specifically tuned for use in the ultraviolet, blue or green regions of the spectrum. The QE values exceed 30% at maximum response, and the dark count rate is found to be as low as 30 Hz/cm2 at room temperature. This combination of properties along with a fast temporal response makes these photocathodes ideal for application in photon counting detectors, which is demonstrated with an MCP photomultiplier tube for single and multi-photoelectron detection.

  13. Mode-resolved Photon Counting via Cascaded Quantum Frequency Conversion

    CERN Document Server

    Huang, Yu-Ping

    2012-01-01

    Resources for the manipulation and measurements of high-dimensional photonic signals are crucial for implementing qu$d$it-based applications. Here we propose potentially high-performance, chip-compatible devices for such purposes by exploiting quantum-frequency conversion in nonlinear optical media. Specifically, by using sum-frequency generation in a $\\chi^{(2)}$ waveguide we show how mode-resolved photon counting can be accomplished for telecom-band photonic signals subtending multiple temporal modes. Our method is generally applicable to any nonlinear medium with arbitrary dispersion property.

  14. Improved photon counting efficiency calibration using superconducting single photon detectors

    Science.gov (United States)

    Gan, Haiyong; Xu, Nan; Li, Jianwei; Sun, Ruoduan; Feng, Guojin; Wang, Yanfei; Ma, Chong; Lin, Yandong; Zhang, Labao; Kang, Lin; Chen, Jian; Wu, Peiheng

    2015-10-01

    The quantum efficiency of photon counters can be measured with standard uncertainty below 1% level using correlated photon pairs generated through spontaneous parametric down-conversion process. Normally a laser in UV, blue or green wavelength range with sufficient photon energy is applied to produce energy and momentum conserved photon pairs in two channels with desired wavelengths for calibration. One channel is used as the heralding trigger, and the other is used for the calibration of the detector under test. A superconducting nanowire single photon detector with advantages such as high photon counting speed (optical spectroscopy, super resolution microscopy, deep space observation, and so on.

  15. Ghosting phenomena in single photon counting imagers with Vernier anode.

    Science.gov (United States)

    Yang, Hao; Zhao, Baosheng; Qiurong, Yan; Liu, Yong'an; Hu, Huijun

    2011-02-01

    We provide the ghosting theory of two-dimensional Vernier anode based imagers. The single photon counting detection system based on Vernier anode is constructed. The ghosting, which occurs during the decoding of two-dimensional Vernier anode, and its possible solutions are described in detail. On the basis of the discussion of the decoding algorithm, the ghosting theoretical model is established. Phase conditions on which imaging ghosting can be avoided and the probability distribution function are proposed; the root causes of ghosting of two-dimensional Vernier anode are also discussed.

  16. 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.

  17. Single Photon Counting Detectors for Low Light Level Imaging Applications

    Science.gov (United States)

    Kolb, Kimberly

    2015-10-01

    This dissertation presents the current state-of-the-art of semiconductor-based photon counting detector technologies. HgCdTe linear-mode avalanche photodiodes (LM-APDs), silicon Geiger-mode avalanche photodiodes (GM-APDs), and electron-multiplying CCDs (EMCCDs) are compared via their present and future performance in various astronomy applications. LM-APDs are studied in theory, based on work done at the University of Hawaii. EMCCDs are studied in theory and experimentally, with a device at NASA's Jet Propulsion Lab. The emphasis of the research is on GM-APD imaging arrays, developed at MIT Lincoln Laboratory and tested at the RIT Center for Detectors. The GM-APD research includes a theoretical analysis of SNR and various performance metrics, including dark count rate, afterpulsing, photon detection efficiency, and intrapixel sensitivity. The effects of radiation damage on the GM-APD were also characterized by introducing a cumulative dose of 50 krad(Si) via 60 MeV protons. Extensive development of Monte Carlo simulations and practical observation simulations was completed, including simulated astronomical imaging and adaptive optics wavefront sensing. Based on theoretical models and experimental testing, both the current state-of-the-art performance and projected future performance of each detector are compared for various applications. LM-APD performance is currently not competitive with other photon counting technologies, and are left out of the application-based comparisons. In the current state-of-the-art, EMCCDs in photon counting mode out-perform GM-APDs for long exposure scenarios, though GM-APDs are better for short exposure scenarios (fast readout) due to clock-induced-charge (CIC) in EMCCDs. In the long term, small improvements in GM-APD dark current will make them superior in both long and short exposure scenarios for extremely low flux. The efficiency of GM-APDs will likely always be less than EMCCDs, however, which is particularly disadvantageous for

  18. Near UV imager with an MCP-based photon counting detector

    Science.gov (United States)

    Ambily, S.; Mathew, Joice; Sarpotdar, Mayuresh; Sreejith, A. G.; Nirmal, K.; Prakash, Ajin; Safonova, Margarita; Murthy, Jayant

    2016-07-01

    We are developing a compact UV Imager using light weight components, that can be own on a small CubeSat or a balloon platform. The system has a lens-based optics that can provide an aberration-free image over a wide field of view. The backend instrument is a photon counting detector with off-the-shelf MCP, CMOS sensor and electronics. We are using a Z-stack MCP with a compact high voltage power supply and a phosphor screen anode, which is read out by a CMOS sensor and the associated electronics. The instrument can be used to observe solar system objects and detect bright transients from the upper atmosphere with the help of CubeSats or high altitude balloons. We have designed the imager to be capable of working in direct frame transfer mode as well in the photon-counting mode for single photon event detection. The identification and centroiding of each photon event are done using an FPGA-based data acquisition and real-time processing system.

  19. Advanced time-correlated single photon counting techniques

    CERN Document Server

    Becker, Wolfgang

    2005-01-01

    Time-correlated single photon counting (TCSPC) is a remarkable technique for recording low-level light signals with extremely high precision and picosecond-time resolution. TCSPC has developed from an intrinsically time-consuming and one-dimensional technique into a fast, multi-dimensional technique to record light signals. So this reference and text describes how advanced TCSPC techniques work and demonstrates their application to time-resolved laser scanning microscopy, single molecule spectroscopy, photon correlation experiments, and diffuse optical tomography of biological tissue. It gives practical hints about constructing suitable optical systems, choosing and using detectors, detector safety, preamplifiers, and using the control features and optimising the operating conditions of TCSPC devices. Advanced TCSPC Techniques is an indispensable tool for everyone in research and development who is confronted with the task of recording low-intensity light signals in the picosecond and nanosecond range.

  20. 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.

  1. OPTIMA A Photon Counting High-Speed Photometer

    CERN Document Server

    Straubmeier, C; Schrey, F

    2001-01-01

    OPTIMA is a small, versatile high-speed photometer which is primarily intended for time resolved observations of young high energy pulsars at optical wavelengths. The detector system consists of eight fiber fed photon counters based on avalanche photodiodes, a GPS timing receiver, an integrating CCD camera to ensure the correct pointing of the telescope and a computerized control unit. Since January 1999 OPTIMA proves its scientific potential by measuring a very detailed lightcurve of the Crab Pulsar as well as by observing cataclysmic variable stars on very short timescales. In this article we describe the design of the detector system focussing on the photon counting units and the software control which correlates the detected photons with the GPS timing signal.

  2. Design and construction of a photon counting system

    Science.gov (United States)

    Pérez, F. R.; Del Valle, C.; Reyes, L.; Tobón, J.; Barrero, C.; Velásquez, A.

    2007-03-01

    This article describes the design and implementation of a photon counting system, which is made using low cost electronic devices. The system is connected to a spectrometer in order to study events related to low levels of luminance intensity. It uses a photo-multiplier tube (PMT) for photon detection. The counting photon system is conformed by 5 stages, which are: the detector, a pre-amplifier, a pulse comparator, a pulses counter and a communications interface in a PC. Data acquisition is done through the serial port. The system allows the detection of radiation coming from signals whose counting rates are several thousands pulses per second. As an application of the system, the Raman Stokes spectrum of the polystyrene as well as the fluorescence band of an organic pigment on a poly-vinyl matrix is showed.

  3. Photon counting phosphorescence lifetime imaging with TimepixCam

    Science.gov (United States)

    Hirvonen, Liisa M.; Fisher-Levine, Merlin; Suhling, Klaus; Nomerotski, Andrei

    2017-01-01

    TimepixCam is a novel fast optical imager based on an optimized silicon pixel sensor with a thin entrance window and read out by a Timepix Application Specific Integrated Circuit. The 256 × 256 pixel sensor has a time resolution of 15 ns at a sustained frame rate of 10 Hz. We used this sensor in combination with an image intensifier for wide-field time-correlated single photon counting imaging. We have characterised the photon detection capabilities of this detector system and employed it on a wide-field epifluorescence microscope to map phosphorescence decays of various iridium complexes with lifetimes of about 1 μs in 200 μm diameter polystyrene beads.

  4. Quantum-enhanced microscopy with binary-outcome photon counting

    Science.gov (United States)

    Jin, G. R.; Yang, W.; Sun, C. P.

    2017-01-01

    Polarized light microscopy using path-entangled N -photon states (i.e., the N00N states) has been demonstrated to surpass the shot-noise limit at very low light illumination. However, the microscopy images suffer from divergence of phase sensitivity, which inevitably reduces the image quality. Here we show that due to experimental imperfections, such a singularity also takes place in the microscopy that uses twin-Fock states of light for illumination. We propose two schemes to completely eliminate this singularity: (i) locking the phase shift sensed by the beams at the optimal working point using a spatially dependent offset phase; (ii) a combination of two binary-outcome photon counting measurements, one with a fixed offset phase and the other without any offset phase. Our observations remain valid for any kind of binary-outcome measurement and may open the way for quantum-enhanced microscopy with high N photon states.

  5. Imaging by photon counting with 256x256 pixel matrix

    Science.gov (United States)

    Tlustos, Lukas; Campbell, Michael; Heijne, Erik H. M.; Llopart, Xavier

    2004-09-01

    Using 0.25µm standard CMOS we have developed 2-D semiconductor matrix detectors with sophisticated functionality integrated inside each pixel of a hybrid sensor module. One of these sensor modules is a matrix of 256x256 square 55µm pixels intended for X-ray imaging. This device is called 'Medipix2' and features a fast amplifier and two-level discrimination for signals between 1000 and 100000 equivalent electrons, with overall signal noise ~150 e- rms. Signal polarity and comparator thresholds are programmable. A maximum count rate of nearly 1 MHz per pixel can be achieved, which corresponds to an average flux of 3x10exp10 photons per cm2. The selected signals can be accumulated in each pixel in a 13-bit register. The serial readout takes 5-10 ms. A parallel readout of ~300 µs could also be used. Housekeeping functions such as local dark current compensation, test pulse generation, silencing of noisy pixels and threshold tuning in each pixel contribute to the homogeneous response over a large sensor area. The sensor material can be adapted to the energy of the X-rays. Best results have been obtained with high-resistivity silicon detectors, but also CdTe and GaAs detectors have been used. The lowest detectable X-ray energy was about 4 keV. Background measurements have been made, as well as measurements of the uniformity of imaging by photon counting. Very low photon count rates are feasible and noise-free at room temperature. The readout matrix can be used also with visible photons if an energy or charge intensifier structure is interposed such as a gaseous amplification layer or a microchannel plate or acceleration field in vacuum.

  6. Novel photon-counting low-dose computed tomography using a multi-pixel photon counter

    Science.gov (United States)

    Morita, H.; Oshima, T.; Kataoka, J.; Arimoto, M.; Nitta, H.

    2017-06-01

    X-ray computed tomography (CT) is widely used in diagnostic imaging. Owing to a strong radiation exposure associated with this method, numerous proposals have been made for reducing the radiation dose. In addition, conventional CT does not provide information on the energy associated with each X-ray photon because intensity is rather high, typically amounts to 10 7 - 9 cps /mm2 . Here, we propose a novel, low-dose photon-counting CT system based on a multi-pixel photon counter (MPPC) and a high-speed scintillator. To demonstrate high signal-to-noise ratio utilizing the internal gain and the fast time response of the MPPC, we compared CT images acquired under the same conditions among a photodiode (PD), an avalanche photodiode and a MPPC. In particular, the images' contrast-to-noise ratio (CNR) acquired using the MPPC improved 12.6-fold compared with the images acquired in conventional CT using a PD. We also performed energy-resolved imaging by adopting 4 energy thresholds of 20, 40, 60, and 80 keV. We confirmed a substantial improvement of the imaging contrast as well as a reduction in the beam hardening for the CT images. We conclude that the proposed MPPC-based detector is likely to be a promising device for use in future CT scanners.

  7. 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.

  8. Prospects of photon counting lidar for savanna ecosystem structural studies

    Science.gov (United States)

    Gwenzi, D.; Lefsky, M. A.

    2014-11-01

    Discrete return and waveform lidar have demonstrated a capability to measure vegetation height and the associated structural attributes such as aboveground biomass and carbon storage. Since discrete return lidar (DRL) is mainly suitable for small scale studies and the only existing spaceborne lidar sensor (ICESat-GLAS) has been decommissioned, the current question is what the future holds in terms of large scale lidar remote sensing studies. The earliest planned future spaceborne lidar mission is ICESat-2, which will use a photon counting technique. To pre-validate the capability of this mission for studying three dimensional vegetation structure in savannas, we assessed the potential of the measurement approach to estimate canopy height in a typical savanna landscape. We used data from the Multiple Altimeter Beam Experimental Lidar (MABEL), an airborne photon counting lidar sensor developed by NASA Goddard. MABEL fires laser pulses in the green (532 nm) and near infrared (1064 nm) bands at a nominal repetition rate of 10 kHz and records the travel time of individual photons that are reflected back to the sensor. The photons' time of arrival and the instrument's GPS positions and Inertial Measurement Unit (IMU) orientation are used to calculate the distance the light travelled and hence the elevation of the surface below. A few transects flown over the Tejon ranch conservancy in Kern County, California, USA were used for this work. For each transect we extracted the data from one near infrared channel that had the highest number of photons. We segmented each transect into 50 m, 25 m and 10 m long blocks and aggregated the photons in each block into a histogram based on their elevation values. We then used an expansion window algorithm to identify cut off points where the cumulative density of photons from the highest elevation resembles the canopy top and likewise where such cumulative density from the lowest elevation resembles mean ground elevation. These cut off

  9. Two-dimensional photon counting imaging detector based on a Vernier position sensitive anode readout

    Institute of Scientific and Technical Information of China (English)

    鄢秋荣; 赵宝升; 刘永安; 杨颢; 盛立志; 韦永林

    2011-01-01

    A two-dimensional photon counting imaging detector based on a Vernier position sensitive anode is reported. The decode principle and design of a two-dimensional Vernier anode are introduced in detail. A photon counting imaging system was built based on a

  10. 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.

  11. Photon counting spectroscopic CT with dynamic beam attenuator

    CERN Document Server

    Atak, Haluk

    2016-01-01

    Purpose: Photon counting (PC) computed tomography (CT) can provide material selective CT imaging at lowest patient dose but it suffers from suboptimal count rate. A dynamic beam attenuator (DBA) can help with count rate by modulating x-ray beam intensity such that the low attenuating areas of the patient receive lower exposure, and detector behind these areas is not overexposed. However, DBA may harden the beam and cause artifacts and errors. This work investigates positive and negative effects of using DBA in PCCT. Methods: A simple PCCT with single energy bin, spectroscopic PCCT with 2 and 5 energy bins, and conventional energy integrating CT with and without DBA were simulated and investigated using 120kVp tube voltage and 14mGy air dose. The DBAs were modeled as made from soft tissue (ST) equivalent material, iron (Fe), and holmium (Ho) K-edge material. A cylindrical CT phantom and chest phantom with iodine and CaCO3 contrast elements were used. Image artifacts and quantification errors in general and mat...

  12. 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...

  13. Development of Data Acquisition Methods for an FPGA-Based Photon Counting Detector

    Science.gov (United States)

    Ambily, S.; Sarpotdar, Mayuresh; Mathew, Joice; Sreejith, A. G.; Nirmal, K.; Prakash, Ajin; Safonova, Margarita; Murthy, Jayant

    MCP-based detectors are widely used in the ultraviolet (UV) region due to their low noise levels, high sensitivity and good spatial and temporal resolution. We have developed a compact near-UV (NUV) detector for high-altitude balloon and space flights, using off-the-shelf MCP, CMOS sensor, and optics. The detector is designed to be capable of working in the direct frame transfer mode as well in the photon counting mode for single photon event detection. The identification and centroiding of each photon event are done using an FPGA-based data acquisition and real-time processing system. In this paper, we discuss various algorithms and methods used in both operating modes, as well as their implementation on the hardware.

  14. On the Single-Photon-Counting (SPC) modes of imaging using an XFEL source

    Science.gov (United States)

    Wang, Zhehui

    2015-12-01

    The requirements to achieve high detection efficiency (above 50%) and gigahertz (GHz) frame rate for the proposed 42-keV X-ray free-electron laser (XFEL) at Los Alamos are summarized. Direct detection scenarios using C (diamond), Si, Ge and GaAs semiconductor sensors are analyzed. Single-photon counting (SPC) mode and weak SPC mode using Si can potentially meet the efficiency and frame rate requirements and be useful to both photoelectric absorption and Compton physics as the photon energy increases. Multilayer three-dimensional (3D) detector architecture, as a possible means to realize SPC modes, is compared with the widely used two-dimensional (2D) hybrid planar electrode structure and 3D deeply entrenched electrode architecture. Demonstration of thin film cameras less than 100-μm thick with onboard thin ASICs could be an initial step to realize multilayer 3D detectors and SPC modes for XFELs.

  15. On the Single-Photon-Counting (SPC) modes of imaging using an XFEL source

    CERN Document Server

    Wang, Zhehui

    2015-01-01

    The requirements to achieve high detection efficiency (above 50\\%) and gigahertz (GHz) frame rate for the proposed 42-keV X-ray free-electron laser (XFEL) at Los Alamos are summarized. Direct detection scenarios using C (diamond), Si, Ge and GaAs semiconductor sensors are analyzed. Single-photon counting (SPC) mode and weak SPC mode using Si can potentially meet the efficiency and frame rate requirements and be useful to both photoelectric absorption and Compton physics as the photon energy increases. Multilayer three-dimensional (3D) detector architecture, as a possible means to realize SPC modes, is compared with the widely used two-dimensional (2D) hybrid planar electrode structure and 3D deeply entrenched electrode architecture. Demonstration of thin film cameras less than 100-$\\mu$m thick with onboard thin ASICs could be an initial step to realize multilayer 3D detectors and SPC modes for XFELs.

  16. Dark-count-less photon-counting x-ray computed tomography system using a YAP-MPPC detector

    Science.gov (United States)

    Sato, Eiichi; Sato, Yuich; Abudurexiti, Abulajiang; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

    2012-10-01

    A high-sensitive X-ray computed tomography (CT) system is useful for decreasing absorbed dose for patients, and a dark-count-less photon-counting CT system was developed. X-ray photons are detected using a YAP(Ce) [cerium-doped yttrium aluminum perovskite] single crystal scintillator and an MPPC (multipixel photon counter). Photocurrents are amplified by a high-speed current-voltage amplifier, and smooth event pulses from an integrator are sent to a high-speed comparator. Then, logical pulses are produced from the comparator and are counted by a counter card. Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan. The image contrast of gadolinium medium slightly fell with increase in lower-level voltage (Vl) of the comparator. The dark count rate was 0 cps, and the count rate for the CT was approximately 250 kcps.

  17. Direct Coupling of SiPMs to Scintillator Tiles for Imaging Calorimetry and Triggering

    CERN Document Server

    Simon, Frank; Joram, Christian

    2010-01-01

    The recent availability of blue sensitive silicon photomultipliers allows the direct readout of blue emitting plastic scintillator tiles without the use of a wavelength shifting fiber. Such directly read out tiles, without light guides, are attractive for the use in highly granular calorimeters that use large numbers of individual cells and in other applications where very compact designs are needed. However, the total signal amplitude and the uniformity of the response can be problematic in such cases. We have developed a scanning setup to investigate the response of scintillator tiles with SiPM readout in detail. It was used to develop optimized scintillator tile geometries for highly granular hadronic calorimetry at future colliders and to investigate the feasibility of a SiPM readout for the trigger of the ATLAS ALFA luminosity detectors. We report on results obtained with specialized scintillator tile geometries, discuss first results obtained with directly coupled SiPM readout of the ATLAS ALFA trigger ...

  18. SWAD: inherent photon counting performance of amorphous selenium multi-well avalanche detector

    Science.gov (United States)

    Stavro, Jann; Goldan, Amir H.; Zhao, Wei

    2016-03-01

    Photon counting detectors (PCDs) have the potential to improve x-ray imaging, however they are still hindered by several performance limitations and high production cost. By using amorphous Selenium (a-Se) the cost of PCDs can be significantly reduced compared to crystalline materials and enable large area detector fabrication. To overcome the problem of low carrier mobility and low charge conversion gain in a-Se, we are developing a novel direct conversion a- Se field-Shaping multi-Well Avalanche Detector (SWAD). SWAD circumvents the charge transport limitation by using a Frisch grid built within the readout circuit, reducing charge collection time to ~200 ns. Field shaping permits depth independent avalanche gain in wells, resulting in total conversion gain that is comparable to Si and CdTe. In the present work we investigate the effects of charge sharing and energy loss to understand the inherent photon counting performance for SWAD at x-ray energies used in breast imaging applications (20-50keV). The energy deposition profile for each interacting x-ray was determined with Monte Carlo simulation. For the energy ranges we are interested in, photoelectric interaction dominates, with a k-fluorescence yield of approximately 60%. Using a monoenergetic 45 keV beam incident on a target pixel in 400um of a-Se, our results show that only 20.42 % and 22.4 % of primary interacting photons have kfluorescence emissions which escape the target pixel for 100um and 85um pixel sizes respectively, demonstrating SWAD's potential for high spatial resolution applications.

  19. Improvement in the energy resolving capabilities of photon counting detectors

    Science.gov (United States)

    Kang, D.; Lim, K. T.; Park, K.; Cho, G.

    2016-12-01

    Patterned pixel array was proposed to increase the number of energy bins in a single pixel of photon counting detectors without adding more comparators and counters. The pixels were grouped into four different types and each pixel has a common threshold and a specific threshold assigned to each pixel type. The common threshold in every pixel records the total number of incident photons regardless of its pixel type and the specific thresholds classify incident photon energies. The patterned pixel array was evaluated with the pinhole gamma camera system based on the XRI-UNO detector flip-chip bonded with a 1mm thick CdTe sensor. The experimental data was acquired with time-over-threshold mode to avoid the charge sharing problem. The shared total charges created by one photon can be found by summing all pixels within the cluster. To correct the different response to the same energy of photon, the energy calibration of the time-over-threshold value was perfomed independently depending on the cluster size. The time-over-threshold values were separated into two energy bins since we assumed that each pixel has two thresholds. Although each pixel has only two thresholds, five images from different energy windows were obtained by sharing the spectal information from four adjacent pixels. Thus, degradation of the spatial resolution in the image occured in each energy window. The image of the entire energy, however, was not degraded since all four different types of pixels have a common threshold just above the noise level. In addition, the number of steps for the threshold scan method can be drastically reduced with the increased number of effective thresholds in a single pixel.

  20. Mcps-range photon-counting X-ray computed tomography system utilizing an oscillating linear-YAP(Ce) photon detector

    Science.gov (United States)

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

    2011-07-01

    High-speed X-ray photon counting is useful for discriminating photon energy, and the counting can be used for constructing an X-ray computed tomography (CT) system. A photon-counting X-ray CT system consists of an X-ray generator, a turntable, an oscillation linear detector, a two-stage controller, a multipixel photon counter (MPPC) module, a 1.0 mm-thick crystal (scintillator) of YAP(Ce) (cerium-doped yttrium aluminum perovskite), a counter card (CC), and a personal computer (PC). Tomography is accomplished by repeating the linear scanning and the rotation of an object, and projection curves of the object are obtained by the linear scanning using the detector consisting of an MPPC module, the YAP(Ce), and a scan stage. The pulses of the event signal from the module are counted by the CC in conjunction with the PC. Because the lower level of the photon energy was roughly determined by a comparator in the module, the average photon energy of the X-ray spectra increased with increase in the lower-level voltage of the comparator at a constant tube voltage. The maximum count rate was approximately 3 Mcps (mega counts per second), and photon-counting CT was carried out.

  1. A Directional Gamma-Ray Detector Based on Scintillator Plates

    CERN Document Server

    Hanna, D; Boyle, P; MacLeod, A M L

    2015-01-01

    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.

  2. Absolute optical responsivity down to the photon counting level with a photomultiplier tube

    Science.gov (United States)

    Tanabe, M.; Niwa, K.; Kinoshita, K.

    2017-04-01

    A novel method is presented for evaluation of the absolute optical responsivity of a photomultiplier tube (PMT) at optical powers down to the photon counting level under visible light. This method is based on a combination of the calibrated responsivity and nonlinearity corrections using a silicon photodiode and a PMT. The evaluation results with the PMT enable accurate determination of the absolute optical responsivity over a wide power range of 10-11 W to 10-16 W under visible light. This method provides validation of both the photon counting efficiency of a PMT and of accurate optical measurement with attenuators at the photon counting level.

  3. Indirect-detection single-photon-counting x-ray detector for breast tomosynthesis

    Science.gov (United States)

    Jiang, Hao; Kaercher, Joerg; Durst, Roger

    2016-03-01

    X-ray mammography is a crucial screening tool for early identification of breast cancer. However, the overlap of anatomical features present in projection images often complicates the task of correctly identifying suspicious masses. As a result, there has been increasing interest in acquisition of volumetric information through digital breast tomosynthesis (DBT) which, compared to mammography, offers the advantage of depth information. Since DBT requires acquisition of many projection images, it is desirable that the noise in each projection image be dominated by the statistical noise of the incident x-ray quanta and not by the additive noise of the imaging system (referred to as quantum-limited imaging) and that the cumulative dose be as low as possible (e.g., no more than for a mammogram). Unfortunately, the electronic noise (~2000 electrons) present in current DBT systems based on active matrix, flat-panel imagers (AMFPIs) is still relatively high compared with modest x-ray gain of the a-Se and CsI:Tl x-ray converters often used. To overcome the modest signal-to-noise ratio (SNR) limitations of current DBT systems, we have developed a large-area x-ray imaging detector with the combination of an extremely low noise (~20 electrons) active-pixel CMOS and a specially designed high resolution scintillator. The high sensitivity and low noise of such system provides better SNR by at least an order of magnitude than current state-of-art AMFPI systems and enables x-ray indirect-detection single photon counting (SPC) at mammographic energies with the potential of dose reduction.

  4. Turn-key Near-Infrared Photon-Counting Detector Module for LIDAR Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Based on the prototype photon counter developed during Phase I, we will deliver a next-generation photon counting detector optimized for LIDAR applications within...

  5. Image-based spectral distortion correction for photon-counting x-ray detectors

    OpenAIRE

    Ding, Huanjun; Molloi, Sabee

    2012-01-01

    Purpose: To investigate the feasibility of using an image-based method to correct for distortions induced by various artifacts in the x-ray spectrum recorded with photon-counting detectors for their application in breast computed tomography (CT).

  6. A Near-Infrared Photon Counting Camera for High Sensitivity Astronomical Observation Project

    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...

  7. High-Sensitivity Semiconductor Photocathodes for Space-Born UV Photon-Counting and Imaging Project

    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...

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

    Science.gov (United States)

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

    2013-10-01

    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.

  9. Photon Counting and Super Homodyne Detection of Weak QPSK Signals for Quantum Key Distribution

    CERN Document Server

    XU, Q; Agnolini, S; Gallion, P; Mendieta, F J

    2006-01-01

    We compare the principles and experimental results of two different QPSK signal detection configurations, photon counting and super homodyning, for applications in fiber-optic Quantum Key Distribution (QKD) systems operating at telecom wavelength, using the BB84 protocol.

  10. Turn-key Near-Infrared Photon-Counting Detector Module for LIDAR Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to design and deliver a turn-key photon counting detector module for near-infrared wavelengths, based on large-area InGaAs/InP avalanche photodiodes...

  11. Highly Sensitive Photon Counting Detectors for Deep Space Optical Communications Project

    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...

  12. Gluing Lidar Signals Detected in Analog-to-Digital and Photon Counting Modes

    Science.gov (United States)

    Feng, Chang-Zhong; Liu, Bing-Yi; Liu, Jin-Tao; Wu, Song-Hua

    2016-06-01

    Lidar is one of the most effective tools for atmospheric remote sensing. For a ground-based lidar system, the backscattered light usually has large dynamic range. Photon-counting mode has the capability to measure weak signal from high altitude, while Analog-to-Digital mode with better linearity is good at measuring strong signal at low altitude. In some lidar systems, atmospheric return signal is measured in both Analog-to-Digital and Photon Counting modes and combined into an entire profile by using a gluing algorithm. A method for gluing atmospheric return signal is developed and tested. For the Photon Counting signal, the saturation characteristics are analyzed to calculate the coefficients for correction. Then the Analog-to-Digital and Photon Counting signals are glued by a weighted average process. Results show the glued signal is reliable at both low and high altitudes.

  13. 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

  14. Multi-channel photon counting three-dimensional imaging laser radar system using fiber array coupled Geiger-mode avalanche photodiode

    Science.gov (United States)

    Shu, Rong; Huang, Genghua; Hou, Libing; He, Zhiping; Hu, Yihua

    2012-09-01

    Photon counting laser radar is the most sensitive and efficiency detection method of direct-detection laser radar. With the use of Geiger-mode avalanche photodiode (APD) or other single photon detectors, every laser photon could be sufficiently used for ranging and three-dimensional imaging. The average energy of received laser signal could be as low as a single photon, or even less than one. This feature of photon counting laser radar enables ranging under conditions of long range, low laser pulse energy, and multi-pixel detection, while receiver size, mass, power, and complexity of laser radar are reduced. In this paper, a latest multi-channel photon counting 3D imaging laser radar system using fiber array coupled Geiger-mode avalanche photodiode (APD) is introduced. Detection model based on Poisson statistics of a photon counting laser radar is discussed. A laser radar system, working under daylight condition with ultra-low signal level (less than single photon per pulse), has been designed and analyzed with the detection model and photon counting three-dimensional imaging theory. A passively Q-switched microchip laser is used to transmit short sub-nanosecond laser pulses at 532nm. The output laser is divided into 1×8 laser spots, which correspond to 8 Geiger-mode avalanche photodiodes coupled by a 1×8-pixel fiber array. A FPGA based time-to-digital converter (TDC), which is designed by delay line interpolation technology, is used for multi-hit signal acquisition. The algorithm of photon counting three-dimensional imaging is developed for signal photon events extraction and noise filter. Three-dimensional images under daylight conditions were acquired and analyzed. The results show that system could operate at strong solar background. The ranging accuracy of the system is 6.3cm (σ) while received laser pulse signal level is only 0.04 photoelectrons on average. The advantages and feasibility of photon counting laser radar working at daylight have been

  15. GPS scintillation effects associated with polar cap patches and substorm auroral activity: direct comparison

    Directory of Open Access Journals (Sweden)

    Jin Yaqi

    2014-01-01

    Full Text Available We directly compare the relative GPS scintillation levels associated with regions of enhanced plasma irregularities called auroral arcs, polar cap patches, and auroral blobs that frequently occur in the polar ionosphere. On January 13, 2013 from Ny-Ålesund, several polar cap patches were observed to exit the polar cap into the auroral oval, and were then termed auroral blobs. This gave us an unprecedented opportunity to compare the relative scintillation levels associated with these three phenomena. The blobs were associated with the strongest phase scintillation (σϕ, followed by patches and arcs, with σϕ up to 0.6, 0.5, and 0.1 rad, respectively. Our observations indicate that most patches in the nightside polar cap have produced significant scintillations, but not all of them. Since the blobs are formed after patches merged into auroral regions, in space weather predictions of GPS scintillations, it will be important to enable predictions of patches exiting the polar cap.

  16. Geant4 simulation of optical photon transport in scintillator tile with direct readout by silicon photomultiplier

    Science.gov (United States)

    Korpachev, S.; Chadeeva, M.

    2017-01-01

    The direct coupling of silicon photomultiplier to the scintillator tile is considered to be the main option for active elements of the highly granular hadron calorimeter developed for future linear collider experiments. In this study, the response of the scintillator-SiPM system to minimum ionising particles was simulated using the optical photon transport functionality available in the Geant4 package. The uniformity of response for both flat tile and tile with dimple was estimated from the simulations and compared to the experimental results obtained in the previous studies.

  17. Metabolic imaging in microregions of tumors and normal tissues with bioluminescence and photon counting

    Energy Technology Data Exchange (ETDEWEB)

    Mueller-Klieser, W.; Walenta, S.; Paschen, W.; Kallinowski, F.; Vaupel, P.

    1988-08-03

    A method has been developed for metabolic imaging on a microscopic level in tumors, tumor spheroids, and normal tissues. The technique makes it possible to determine the spatial distribution of glucose, lactate, and ATP in absolute terms at similar locations within tissues or cell aggregates. The substrate distributions are registered in serial cryostat sections from tissue cryobiopsies or from frozen spheroids with the use of bioluminescence reactions. The light emission is measured directly by a special imaging photon counting system enabling on-line image analysis. The technique has been applied to human breast cancer xenografts, to spheroids originating from a human colon adenocarcinoma, and to skeletal rat muscle. Preliminary data obtained indicate that heterogeneities in the substrate distributions measured are much more pronounced in tumors than in normal tissue. There was no obvious correlation among the three quantities measured at similar locations within the tissues. The distribution of ATP corresponded well with the histological structure of larger spheroids; values were low in the necrotic center and high in the viable rim of these cell aggregates.

  18. Photon-counting chirped amplitude modulation lidar using a smart premixing method.

    Science.gov (United States)

    Zhang, Zijing; Zhang, Jianlong; Wu, Long; Zhang, Yong; Zhao, Yuan; Su, Jianzhong

    2013-11-01

    We proposed a new premixing method for photon-counting chirped amplitude modulation lidar (PCCAML). Earlier studies used the counting results of the returned signal detected by a Geiger mode avalanche photodiode detector (Gm-APD) to mix with the reference signal, called the postmixing method. We use an alternative method known as the premixing method, in which the reference signal is used to directly modulate the sampling gate width of the Gm-APD, and the mixing of the returned signal and the reference signal is completed before the Gm-APD. This premixing method is more flexible and may perform better than the postmixing method in terms of signal-to-noise ratio by cutting down a separated mixer commonly used in the postmixing lidar system. Furthermore, this premixing method lowers the demand for the sampling frequency of the Gm-APD. It allows the use of a much wider modulation bandwidth to improve the range accuracy and resolution. To the best of our knowledge, this is the first report to use the premixing method in the PCCAML system, which will benefit future lidar applications.

  19. First results of a cryogenic optical photon-counting imaging spectrometer using a DROID array

    Science.gov (United States)

    Hijmering, R. A.; Verhoeve, P.; Martin, D. D. E.; Venn, R.; van Dordrecht, A.; Groot, P. J.

    2010-02-01

    Context. We present the first system test in which we demonstrate the concept of using an array of Distributed Read Out Imaging Devices (DROIDs) for optical photon detection. Aims: After the successful S-Cam 3 detector, the next step in the development of a cryogenic optical photon counting imaging spectrometer under the S-Cam project is to increase the field of view using DROIDs. With this modification the field of view of the camera has been increased by a factor of five in a given area while keeping the number of readout channels the same. Methods: The test has been performed using the flexible S-Cam 3 system and exchanging the 10 × 12 Superconducting Tunnel Junction array for a 3 × 20 DROID array. The extra data reduction needed with DROIDs is performed offline. Results: We show that, although the responsivity (number of tunnelled quasiparticles per unit of absorbed photon energy, e-/eV) of the current array is too low for direct astronomical applications, the imaging quality is already good enough for pattern detection and will improve further with increasing responsivity. Conclusions: The obtained knowledge can be used to optimise the system for the use of DROIDs.

  20. First results of a cryogenic optical photon counting imaging spectrometer using a DROID array

    CERN Document Server

    Hijmering, R A; Martin, D D E; Venn, R; van Dordrecht, A; Groot, P J

    2009-01-01

    Context. In this paper we present the first system test in which we demonstrate the concept of using an array of Distributed Read Out Imaging Devices (DROIDs) for optical photon detection. Aims. After the successful S-Cam 3 detector the next step in the development of a cryogenic optical photon counting imaging spectrometer under the S-Cam project is to increase the field of view using DROIDs. With this modification the field of view of the camera has been increased by a factor of 5 in area, while keeping the number of readout channels the same. Methods. The test has been performed using the flexible S-Cam 3 system and exchanging the 10x12 Superconducting Tunnel Junction array for a 3x20 DROID array. The extra data reduction needed with DROIDs is performed offline. Results. We show that, although the responsivity (number of tunnelled quasiparticles per unit of absorbed photon energy, e- /eV) of the current array is too low for direct astronomical applications, the imaging quality is already good enough for pa...

  1. 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

    2016-06-21

    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.

  2. Characterization of a photon counting EMCCD for space-based high contrast imaging spectroscopy of extrasolar planets

    CERN Document Server

    Wilkins, Ashlee N; Norton, Timothy J; Rauscher, Bernard J; Rothe, Johannes F; Malatesta, Michael; Hilton, George M; Bubeck, James R; Grady, Carol A; Lindler, Don J

    2014-01-01

    We present the progress of characterization of a low-noise, photon counting Electron Multiplying Charged Coupled Device (EMCCD) operating in optical wavelengths and demonstrate possible solutions to the problems of Clock-Induced Charge (CIC) and other trapped charge through sub-bandgap illumination. Such a detector will be vital to the feasibility of future space-based direct imaging and spectroscopy missions for exoplanet characterization, and is scheduled to fly on-board the AFTA-WFIRST mission. The 512$\\times$512 EMCCD is an e2v detector housed and clocked by a N\\"uv\\"u Cameras controller. Through a multiplication gain register, this detector produces as many as 5000 electrons for a single, incident-photon-induced photoelectron produced in the detector, enabling single photon counting operation with read noise and dark current orders of magnitude below that of standard CCDs. With the extremely high contrasts (Earth-to-Sun flux ratio is $\\sim$ 10$^{-10}$) and extremely faint targets (an Earth analog would m...

  3. Optimization of the uniformity of light yield from scintillator tiles read out directly by silicon photomultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Bobchenko, B.; Chadeeva, M. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Moscow Engineering Physics Institute, Moscow (Russian Federation); Danilov, M. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Moscow Engineering Physics Institute, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny (Russian Federation); Mironov, D., E-mail: dima.mironov@itep.ru [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Moscow Engineering Physics Institute, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny (Russian Federation); Rusinov, V.; Tarkovskiy, E. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Moscow Engineering Physics Institute, Moscow (Russian Federation)

    2015-07-01

    The scintillator tiles with direct readout by silicon photomultipliers (SiPM) have been studied. The SiPM is placed inside the dimple machined in the center of the big face of 30×30×3 mm{sup 3} tile. The different dimple geometries were studied. The tiles with the optimal dimple design show the uniformity of response comparable to the tiles with fiber readout. The direct-readout approach provides a reasonable way for the construction of supermultichannel calorimeters.

  4. 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

    2016-07-20

    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.

  5. Measurements of the direction of the solar wind using interplanetary scintillation

    Directory of Open Access Journals (Sweden)

    P. J. Moran

    Full Text Available EISCAT observations of the interplanetary scintillation of a single source were made over an extended period of time, during which the orientation of the baselines between the two observing sites changed significantly. Assuming that maximum correlation between the scintillations observed at the two sites occurs when the projected baseline is parallel to the direction of plasma flow, this technique can be used to make a unique determination of the direction of the solar wind. In the past it has usually been assumed that the plasma flow is radial, but measurements of eleven sources using this technique have indicated conclusively that in at least six cases observed at mid or high heliocentric latitude there is a significant non-radial component directed in four cases towards the heliocentric equator and in two cases towards the pole.

    Key words. Solar physics · Astrophysics · Astronomy · Magnetic fields · Space plasma physics · Charged particle motion and acceleration

  6. Photoionization of Trapped Carriers in Avalanche Photodiodes to Reduce Afterpulsing During Geiger-Mode Photon Counting

    Science.gov (United States)

    Krainak, Michael A.

    2005-01-01

    We reduced the afterpulsing probability by a factor of five in a Geiger-mode photon-counting InGaAs avalanche photodiode by using sub-band-gap (lambda = 1.95 micron) laser diode illumination, which we believe photoionizes the trapped carriers.

  7. Calibration of photon counting imaging microchannel plate detectors for EUV astronomy

    Science.gov (United States)

    Siegmund, O. H. W.; Vallerga, J.; Jelinsky, P.

    1986-01-01

    The calibration of photon counting imaging detectors for satellite based EUV astronomy is a complex process designed to ensure the validity of the data received 'in orbit'. The methods developed to accomplish calibration of microchannel plate detectors for the Extreme Ultraviolet Explorer are described and illustrated. The characterization of these detectors can be subdivided into three categories: stabilization, performance tests, and environmental tests.

  8. Fluorescence lifetime imaging by time-correlated single-photon counting

    NARCIS (Netherlands)

    Becker, W.; Bergmann, A.; Hink, M.A.; Konig, K.; Benndorf, K.; Biskup, C.

    2004-01-01

    We present a time-correlated single photon counting (TCPSC) technique that allows time-resolved multi-wavelength imaging in conjunction with a laser scanning microscope and a pulsed excitation source. The technique is based on a four-dimensional histogramming process that records the photon density

  9. 6 Mcps photon-counting X-ray computed tomography system using a 25 mm/s-scan linear LSO-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); 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; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya [The 3rd Department of Surgery, Toho University School of Medicine, 2-17-6 Ohashi, Meguro-ku, Tokyo, Iwate 153-8515 (Japan); Sugimura, Shigeaki [Tokyo Denpa Co. Ltd., 82-5 Ueno, Ichinohe, Iwate 028-5321 (Japan); Endo, Haruyuki [Iwate Industrial Research Institute, 3-35-2 Shinden, Iioka, Morioka, Iwate 020-0852 (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)

    2011-12-15

    6 Mcps photon counting was carried out using a detector consisting of a 1.0 mm-thick LSO [Lu{sub 2}(SiO{sub 4})O] single-crystal scintillator and an MPPC (multipixel photon counter) module in an X-ray computed tomography (CT) system. The maximum count rate was 6 Mcps (mega counts per second) at a tube voltage of 100 kV and a tube current of 0.91 mA. Next, a photon-counting X-ray CT system consists of an X-ray generator, a turntable, a scan stage, a two-stage controller, the LSO-MPPC detector, a counter card (CC), and a personal computer (PC). Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan with a scan velocity of 25 mm/s. The pulses of the event signal from the module are counted by the CC in conjunction with the PC. The exposure time for obtaining a tomogram was 600 s at a scan step of 0.5 mm and a rotation step of 1.0{sup o}, and photon-counting CT was accomplished using gadolinium-based contrast media. - Highlights: > 6 Mcps photon counting X-ray CT performed by repeated linear scans and rotations of an object. > Detector consists of an LSO scintillator and an MPPC (multipixel photon counter) module. > Projection curves of the object obtained by the linear scan with a velocity of 25 mm/s. > Exposure time was 600 s. CT was carried out using gadolinium-based contrast media.

  10. 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

  11. Light Pulses to Photomultipliers from Extended Scintillators

    CERN Document Server

    Boemi, D; CERN. Geneva; Costa, S; Insolia, A; Panebianco, S; Potenza, R; Randazzo, N; Reito, S; Romanski, J; Russo, G V; Tuvé, C

    1994-01-01

    Light pulses received by photomultipliers coupled to scintillators are investigated in the cases of long scintillator slats or rods as well as large disc-shaped ones and compared with pulses from point-like scintillators. Results of experimental tests for the disc-shaped configuration performed with the single photon counting technique are presented and compared with numerical calculations. The calculations were done describing light pulse shape by means of a quite new general analytical method based on virtual light paths and images from geometrical optics. The associated electric pulses from the photomultipliers are then discussed and their dependence from source-photocathode distance are put in light.

  12. 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.

  13. 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

  14. Relative scintillation efficiency of liquid xenon in the XENON10 direct dark matter search

    Science.gov (United States)

    Manzur, Angel

    There is almost universal agreement that most of the mass in the Universe consists of dark matter. Many lines of reasoning suggest that the dark matter consists of a weakly interactive massive particle (WIMP) with mass ranging from 10 GeV/c 2 to a few TeV/c 2 . Today, numerous experiments aim for direct or indirect dark matter detection. XENON10 is a direct detection experiment using a xenon dual phase time projection chamber. Particles interacting with xenon will create a scintillation signal ( S 1) and ionization. The charge produced is extracted into the gas phase and converted into a proportional scintillation light ( S 2), with an external electric field. The dominant background, b particles and g rays, will undergo an electron recoil (ER) interaction, while WIMPs and neutrons will undergo a nuclear recoil (NR) interaction. Event-by-event discrimination of background signals is based on log 10 ( S 2/ S 1) NR review the requirements for a dark matter search. In particular I discuss the XENON10 detector, deployment, operation, calibrations, analysis and WIMP-nucleon cross- section limits. Finally, I present our latest results for the relative scintillation efficiency ([Special characters omitted.] ) for nuclear recoils in liquid xenon, which was the biggest source of uncertainty in the XENON10 limit. This quantity is essential to determine the nuclear energy scale and to determine the WIMP-nucleon cross sections.

  15. CLARO-CMOS, an ASIC for single photon counting with Ma-PMTs, MCPs and SiPMs

    Science.gov (United States)

    Carniti, P.; Cibinetto, G.; Cotta Ramusino, A.; Giachero, A.; Gotti, C.; Maino, M.; Malaguti, R.; Pessina, G.

    2013-01-01

    An ASIC named CLARO-CMOS was designed for fast photon counting with MaPMTs, MCPs and SiPMs. The prototype was realized in a .35 μm CMOS technology and has four channels, each with a fast amplifier and a discriminator. The main features of the design are the high speed of operation and the low power dissipation, below 1 mW per channel. This paper focuses on the use of the CLARO for SiPM readout. The ASIC was tested with several SiPMs of various sizes, connected to the input of the chip both directly and through a coaxial cable about one meter long. In the latter case the ASIC is still fully functional although the speed of response is affected by the cable capacitance. The threshold could be set just above the single photoelectron level, and with 1 ×1 mm2 SiPMs the discrete photoelectron peaks could be well resolved.

  16. Spectral lesion characterization on a photon-counting mammography system

    Science.gov (United States)

    Erhard, Klaus; Fredenberg, Erik; Homann, Hanno; Roessl, Ewald

    2014-03-01

    Spectral X-ray imaging allows to differentiate between two given tissue types, provided their spectral absorption characteristics differ measurably. In mammography, this method is used clinically to determine a decomposition of the breast into adipose and glandular tissue compartments, from which the glandular tissue fraction and, hence, the volumetric breast density (VBD) can be computed. Another potential application of this technique is the characterization of lesions by spectral mammography. In particular, round lesions are relatively easily detected by experienced radiologists, but are often difficult to characterize. Here, a method is described that aims at discriminating cystic from solid lesions directly on a spectral mammogram, obtained with a calibrated spectral mammography system and using a hypothesis-testing algorithm based on a maximum likelihood approach. The method includes a parametric model describing the lesion shape, compression height variations and breast composition. With the maximum likelihood algorithm, the model parameters are estimated separately under the cyst and solid hypothesis. The resulting ratio of the maximum likelihood values is used for the final tissue characterization. Initial results using simulations and phantom measurements are presented.

  17. VHF scintillations, orientation of the anisotropy of F-region irregularities and direction of plasma convection in the polar cap

    Directory of Open Access Journals (Sweden)

    E. D. Tereshchenko

    2008-06-01

    Full Text Available Scintillation data recorded at the polar cap station Barentsburg are shown to occasionally exhibit two or more peaks in the latitudinal profiles of the amplitude dispersion. Comparison with concurrent SuperDARN radar convection maps indicates that multiple peaks occur when Barentsburg is located within the area of strong changes in the plasma flow direction. When parameters of the ionospheric irregularities are inferred from the scintillation data, the orientation of the irregularity anisotropy in a plane perpendicular to the magnetic field is found to coincide well with the E×B flow direction, individually for each peak of the scintillation data. The differences were found to be mostly less than 20° for a data set comprised of 104 events. The conclusion is made that analysis of scintillation data allows one to infer the direction of plasma flow with a certain degree of detail.

  18. Prompt directional detection of galactic supernova by combining large liquid scintillator neutrino detectors

    CERN Document Server

    Fischer, V; Lasserre, T; Volpe, C; Cribier, M; Durero, M; Gaffiot, J; Houdy, T; Letourneau, A; Mention, G; Pequignot, M; Sibille, V; Vivier, M

    2015-01-01

    Core-collapse supernovae produce an intense burst of electron antineutrinos in the few-tens-of-MeV range. Several Large Liquid Scintillator-based Detectors (LLSD) are currently operated worldwide, being very effective for low energy antineutrino detection through the Inverse Beta Decay (IBD) process. In this article, we develop a procedure for the prompt extraction of the supernova location by revisiting the details of IBD kinematics over the broad energy range of supernova neutrinos. Combining all current scintillator-based detector, we show that one can locate a canonical supernova at 10 kpc with an accuracy of 45 degrees (68% C.L.). After the addition of the next generation of scintillator-based detectors, the accuracy could reach 12 degrees (68% C.L.), therefore reaching the performances of the large water Cerenkov neutrino detectors. We also discuss a possible improvement of the SuperNova Early Warning System (SNEWS) inter-experiment network with the implementation of a directionality information in each...

  19. Discerning Aggregation in Homogeneous Ensembles: A General Description of Photon Counting Spectroscopy in Diffusing Systems

    CERN Document Server

    Ren, H; Altan-Bonnet, G; Libchaber, A; Ren, Hai-cang; Goddard, Noel L.; Altan-Bonnet, Gregoire; Libchaber, Albert

    2004-01-01

    In order to discern aggregation in solutions, we present a quantum mechanical analog of the photon statistics from fluorescent molecules diffusing through a focused beam. A generating functional is developed to fully describe the experimental physical system as well as the statistics. Histograms of the measured time delay between photon counts are fit by an analytical solution describing the static as well as diffusing regimes. To determine empirical fitting parameters, fluorescence correlation spectroscopy is used in parallel to the photon counting. For expedient analysis, we find that the distribution's deviation from a single Poisson shows a difference between two single fluor moments or a double fluor aggregate of the same total intensities. Initial studies were performed on fixed-state aggregates limited to dimerization. However preliminary results on reactive species suggest that the method can be used to characterize any aggregating system.

  20. 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.

  1. 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...

  2. Three dimensional object recognition with photon counting imagery in the presence of noise.

    Science.gov (United States)

    DaneshPanah, Mehdi; Javidi, Bahram; Watson, Edward A

    2010-12-06

    Three dimensional (3D) imaging systems have been recently suggested for passive sensing and recognition of objects in photon-starved environments where only a few photons are emitted or reflected from the object. In this paradigm, it is important to make optimal use of limited information carried by photons. We present a statistical framework for 3D passive object recognition in presence of noise. Since in quantum-limited regime, detector dark noise is present, our approach takes into account the effect of noise on information bearing photons. The model is tested when background noise and dark noise sources are present for identifying a target in a 3D scene. It is shown that reliable object recognition is possible in photon-counting domain. The results suggest that with proper translation of physical characteristics of the imaging system into the information processing algorithms, photon-counting imagery can be used for object classification.

  3. 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.

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

    Science.gov (United States)

    Luo, Guang; Xiao, Guangyu

    2014-10-30

    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.

  5. Two-dimensional photon counting imaging detector based on a Vernier position sensitive anode readout

    Institute of Scientific and Technical Information of China (English)

    YAN Qiu-Rong; ZHAO Bao-Sheng; LIU Yong-An; YANG Hao; SHENG Li-Zhi; WEI Yong-Lin

    2011-01-01

    A two-dimensional photon counting imaging detector based on a Vernier position sensitive anode is reported. The decode principle and design of a two-dimensionai Vernier anode axe introduced in detail. A photon counting imaging system was built based on a Vernier anode. The image of very weak optical radiation can be reconstructed by image processing in a period of integration time. The resolution is superior to 100 μm according to the resolution test. The detector may realize the imaging of very weak particle flow of high- energy photons, electrons and ions, so it can be used for high-energy physics, deep space exploration, spectral measurement and bio-luminescence detection.

  6. Single-shot x-ray phase imaging with grating interferometry and photon-counting detectors.

    Science.gov (United States)

    Wang, Zhili; Gao, Kun; Wang, Dajiang; Wu, Zhao; Chen, Heng; Wang, Shenghao; Wu, Ziyu

    2014-02-15

    In this Letter, we present a single-shot approach to quantitatively retrieve x-ray absorption and phase shift in grating interferometry. The proposed approach makes use of the energy-resolving capability of x-ray photon-counting detectors. The retrieval method is derived and presented and is tested based on numerical simulations, including photon shot noise. The good agreement between retrieval results and theoretical values confirms the feasibility of the presented approach.

  7. Simultaneous x-ray fluorescence and K-edge CT imaging with photon-counting detectors

    Science.gov (United States)

    Li, Liang; Li, Ruizhe; Zhang, Siyuan; Chen, Zhiqiang

    2016-10-01

    Rapid development of the X-ray phonon-counting detection technology brings tremendous research and application opportunities. In addition to improvements in conventional X-ray imaging performance such as radiation dose utilization and beam hardening correction, photon-counting detectors allows significantly more efficient X-ray fluorescence (XRF) and K-edge imaging, and promises a great potential of X-ray functional, cellular and molecular imaging. XRF is the characteristic emission of secondary X-ray photons from a material excited by initial X-rays. The phenomenon is widely used for chemical and elemental analysis. K-edge imaging identifies a material based on its chemically-specific absorption discontinuity over X-ray photon energy. In this paper, we try to combine XRF and K-edge signals from the contrast agents (e.g., iodine, gadolinium, gold nanoparticles) to simultaneously realize XFCT and K-edge CT imaging for superior image performance. As a prerequisite for this dual-modality imaging, the accurate energy calibration of multi-energy-bin photon-counting detectors is critically important. With the measured XRF data of different materials, we characterize the energy response function of a CZT detector for energy calibration and spectrum reconstruction, which can effectively improve the energy resolution and decrease the inconsistence of the photon counting detectors. Then, a simultaneous K-edge and X-ray fluorescence CT imaging (SKYFI) experimental setup is designed which includes a cone-beam X-ray tube, two separate photon counting detector arrays, a pin-hole collimator and a rotation stage. With a phantom containing gold nanoparticles the two types of XFCT and K-edge CT datasets are collected simultaneously. Then, XFCT and K-edge CT images are synergistically reconstructed in a same framework. Simulation results are presented and quantitative analyzed and compared with the separate XFCT and K-edge CT results.

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

    OpenAIRE

    Hirvonen, Liisa Maija; Barber, Matthew; 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, w...

  9. Development of photodetectors for recording lidar signals in the photon counting and analog modes

    Science.gov (United States)

    Slesar, A. S.; Chaikovskii, A. P.; Denisov, S. V.; Korol, M. M.; Osipenko, F. P.; Balin, Yu. S.; Kokhanenko, G. P.; Penner, I. E.; Novoselov, M. M.

    2015-11-01

    A number of unified photodetector modules providing for recording lidar signals in the wavelength range from 0.26 to 1.6 μm in the modes of analog signals and photon counting are developed on the basis of photomultiplier tubes and avalanche photodiodes. The software is created for control of the photodetector modules, as well as the test bench for measuring their characteristics is designed.

  10. Optimised data-gluing method for mixed analog/photon-counting lidar signals

    OpenAIRE

    Lange, Diego; Kumar, Dhiraj; Rocadenbosch Burillo, Francisco; Sicard, Michaël; Comerón Tejero, Adolfo

    2011-01-01

    In atmospheric LIDAR (Light Detection and Ranging) remote sensing, the dynamic range of the return power signals can span up to five orders of magnitude. Modern acquisition systems such as those based on LicelTM transient recorders combine a dual acquisition mode in which the return signal is recorded simultaneously in both analog (analog-to-digital (AD) conversion) and photon-counting (PC) modes. Although both data records can be analyzed separately, their combination obtained th...

  11. Comparison of spectral CT imaging methods based a photon-counting detector: Experimental study

    Science.gov (United States)

    Lee, Youngjin; Lee, Seungwan; Kim, Hee-Joung

    2016-04-01

    Photon-counting detectors allow spectral computed tomography (CT) imaging using energy-resolved information from a polychromatic X-ray spectrum. The spectral CT images based on the photon-counting detectors are dependent on the energy ranges defined by energy bins for image acquisition. In this study, K-edge and energy weighting imaging methods were experimentally implemented by using a spectral CT system with a cadmium zinc telluride (CZT)-based photon-counting detector. The spectral CT images were obtained by various energy bins and compared in terms of CNR improvement for investigating the effect of energy bins and the efficiency of the spectral CT imaging methods. The results showed that the spectral CT image quality was improved by using the particular energy bins, which were optimized for each spectral CT imaging method and target material. The CNR improvement was different for the spectral CT imaging methods and target materials. It can be concluded that an appropriate selection of imaging method for each target material and the optimization of energy bin can maximize the quality of spectral CT images.

  12. Improving material decomposition by spectral optimization of photon counting computed tomography

    Science.gov (United States)

    Polster, C.; Hahn, K.; Gutjahr, R.; Schöck, F.; Kappler, S.; Dietrich, O.; Flohr, T. G.

    2016-03-01

    Photon counting detectors in computed tomography facilitate measurements of spectral distributions of detected X-ray quanta in discrete energy bins. Along with the dependency on wavelength and atomic number of the mass attenuation coefficient, this information allows for reconstruction of CT images of different material bases. Decomposition of two materials is considered standard in today's dual-energy techniques. With photon-counting detectors the decomposition of more than two materials becomes achievable. Efficient detection of CT-typical X-ray spectra is a hard requirement in a clinical environment. This is fulfilled by only a few sensor materials such as CdTe or CdZnTe. In contrast to energy integrating CT-detectors, the pixel dimensions must be reduced to avoid pulse pile-up problems at clinically relevant count rates. However, reducing pixel sizes leads to increased K-escape and charge sharing effects. As a consequence, the correlation between incident and detected X-ray energy is reduced. This degradation is quantified by the detector response function. The goal of this study is to improve the achievable material decomposition by adapting the incident X-ray spectrum with respect to the properties (i.e. the detector response function) of a photon counting detector. A significant improvement of a material decomposition equivalent metric is achievable when using specific materials as X-ray pre-filtration (K-edge filtering) while maintaining the applied patient dose and image quality.

  13. Comparison of spectral CT imaging methods based a photon-counting detector: Experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngjin [Department of Radiological Science, College of Health Science, Eulji University, 553 Sangseong-daero, Seongnam, Gyeonggi-do 461-713 (Korea, Republic of); Lee, Seungwan, E-mail: slee1@konyang.ac.kr [Department of Radiological Science, College of Medical Science, Konyang University, 158 Gwanjeodong-ro, Daejeon 302-812 (Korea, Republic of); Kim, Hee-Joung [Department of Radiological Science, College of Health Science, Yonsei University, 1 Yonseidae-gil, Wonju, Kangwon-do 220-710 (Korea, Republic of)

    2016-04-11

    Photon-counting detectors allow spectral computed tomography (CT) imaging using energy-resolved information from a polychromatic X-ray spectrum. The spectral CT images based on the photon-counting detectors are dependent on the energy ranges defined by energy bins for image acquisition. In this study, K-edge and energy weighting imaging methods were experimentally implemented by using a spectral CT system with a cadmium zinc telluride (CZT)-based photon-counting detector. The spectral CT images were obtained by various energy bins and compared in terms of CNR improvement for investigating the effect of energy bins and the efficiency of the spectral CT imaging methods. The results showed that the spectral CT image quality was improved by using the particular energy bins, which were optimized for each spectral CT imaging method and target material. The CNR improvement was different for the spectral CT imaging methods and target materials. It can be concluded that an appropriate selection of imaging method for each target material and the optimization of energy bin can maximize the quality of spectral CT images.

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

    Directory of Open Access Journals (Sweden)

    Shouleh Nikzad

    2016-06-01

    Full Text Available 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.

  15. 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.

  16. 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.

  17. 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.

  18. ChromAIX: Fast photon-counting ASIC for Spectral Computed Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Steadman, Roger, E-mail: roger.steadman@philips.com [Philips Research Europe, Weisshausstrasse 2, 52066 Aachen (Germany); Herrmann, Christoph; Muelhens, Oliver [Philips Research Europe, Weisshausstrasse 2, 52066 Aachen (Germany); Maeding, Dale G. [Innovative Design, under contract with Aeroflex Colorado Springs (United States)

    2011-08-21

    X-ray attenuation properties of matter (i.e. human body in medical Computed Tomography) are energy and material dependent. This dependency is largely neglected in conventional CT techniques, which require the introduction of correction algorithms in order to prevent image artefacts. The exploitation of the inherent energy information contained in the X-ray spectrum allows distinguishing the two main physical causes of energy-dependent attenuation (photo-electric effect and Compton effect). Currently a number of methods exist that allow assessing the energy-dependent attenuation in conventional systems. These methods consist of using two distinct spectra (kVp switching or dual source) or of discriminating low and high energy photons by means of stacking two detectors. Further improvements can be achieved by transitioning to direct-conversion technologies and counting-mode detection, which inherently exhibits a better signal-to-noise ratio. Further including energy discrimination enables new applications, which are not feasible with dual-energy techniques, e.g. the possibility to discriminate K-edge features (contrast agents, e.g. gadolinium) from other contributions to the X-ray attenuation of a human body. The capability of providing energy-resolved information with two or more independent measurements is referred to as Spectral CT. A new proprietary photon-counting ASIC (ChromAIX) has been developed to provide high count-rate capabilities while offering energy discrimination. ChromAIX consists of a pixel array with an isotropic pitch of 300 {mu}m. Each pixel contains independent discriminators that enable the possibility to discretize the incoming photons into a number of energy levels. Extensive electrical characterization has been carried out to assess the performance in terms of count-rate performance and noise. Observed rates exceed 10 Mcps/pixel (Poissonian, mean incoming rates >27 Mcps). The energy resolution is better than 4.1 keV FWHM and has been shown to

  19. ChromAIX: Fast photon-counting ASIC for Spectral Computed Tomography

    Science.gov (United States)

    Steadman, Roger; Herrmann, Christoph; Mülhens, Oliver; Maeding, Dale G.

    2011-08-01

    X-ray attenuation properties of matter (i.e. human body in medical Computed Tomography) are energy and material dependent. This dependency is largely neglected in conventional CT techniques, which require the introduction of correction algorithms in order to prevent image artefacts. The exploitation of the inherent energy information contained in the X-ray spectrum allows distinguishing the two main physical causes of energy-dependent attenuation (photo-electric effect and Compton effect). Currently a number of methods exist that allow assessing the energy-dependent attenuation in conventional systems. These methods consist of using two distinct spectra (kVp switching or dual source) or of discriminating low and high energy photons by means of stacking two detectors. Further improvements can be achieved by transitioning to direct-conversion technologies and counting-mode detection, which inherently exhibits a better signal-to-noise ratio. Further including energy discrimination enables new applications, which are not feasible with dual-energy techniques, e.g. the possibility to discriminate K-edge features (contrast agents, e.g. gadolinium) from other contributions to the X-ray attenuation of a human body. The capability of providing energy-resolved information with two or more independent measurements is referred to as Spectral CT.A new proprietary photon-counting ASIC (ChromAIX) has been developed to provide high count-rate capabilities while offering energy discrimination. ChromAIX consists of a pixel array with an isotropic pitch of 300 μm. Each pixel contains independent discriminators that enable the possibility to discretize the incoming photons into a number of energy levels. Extensive electrical characterization has been carried out to assess the performance in terms of count-rate performance and noise. Observed rates exceed 10 Mcps/pixel (Poissonian, mean incoming rates >27 Mcps). The energy resolution is better than 4.1 keV FWHM and has been shown to be

  20. Uncertainty evaluation in tritium activity assay in water by using direct liquid scintillation spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Mingote, Raquel Maia; Rocha, Zildete [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Servico de Quimica e Radioquimica]. E-mails: mingote@cdtn.br; rochaz@cdtn.br

    2007-07-01

    Tritium-labeled water is often applied to studies in environmental science, hydrology, biology, oil resources and other research areas. In most cases, the tritium activity is determined by using direct liquid scintillation spectrometry without tritium enrichment. A comprehensive uncertainty quantification is so important as accuracy and precision for analysing the results. This paper presents a discussion about the uncertainty propagation law and the partial derivatives method in the tritium assay. It also includes the relations between the tritium activity results and several input parameters. (author)

  1. K-edge imaging in x-ray computed tomography using multi-bin photon counting detectors.

    Science.gov (United States)

    Roessl, E; Proksa, R

    2007-08-07

    After passage through matter, the energy spectrum of a polychromatic beam of x-rays contains valuable information about the elemental composition of the absorber. Conventional x-ray systems or x-ray computed tomography (CT) systems, equipped with scintillator detectors operated in the integrating mode, are largely insensitive to this type of spectral information, since the detector output is proportional to the energy fluence integrated over the whole spectrum. The main purpose of this paper is to investigate to which extent energy-sensitive photon counting devices, operated in the pulse-mode, are capable of revealing quantitative information about the elemental composition of the absorber. We focus on the detection of element-specific, K-edge discontinuities of the photo-electric cross-section. To be specific, we address the question of measuring and imaging the local density of a gadolinium-based contrast agent, in the framework of a generalized dual-energy pre-processing. Our results are very promising and seem to open up new possibilities for the imaging of the distribution of elements with a high atomic number Z in the human body using x-ray attenuation measurements. To demonstrate the usefulness of the detection and the appropriate processing of the spectral information, we present simulated images of an artherosclerotic coronary vessel filled with gadolinium-based contrast agent. While conventional systems, equipped with integrating detectors, often fail to differentiate between contrast filled lumen and artherosclerotic plaque, the use of an energy-selective detection system based on the counting of individual photons reveals a strong contrast between plaque and contrast agent.

  2. Direct detection of sub-GeV dark matter with scintillating targets

    Science.gov (United States)

    Derenzo, Stephen; Essig, Rouven; Massari, Andrea; Soto, Adrián; Yu, Tien-Tien

    2017-07-01

    We suggest a novel experimental concept for detecting MeV-to-GeV-mass dark matter, in which the dark matter scatters off electrons in a scintillating target and produces a signal of one or a few photons. New large-area photodetectors are needed to measure the photon signal with negligible dark counts, which could be constructed from transition edge sensor (TES) or microwave kinetic inductance detector (MKID) technology. Alternatively, detecting two photons in coincidence may allow the use of conventional photodetectors like photomultiplier tubes. We describe why scintillators may have distinct advantages over other experiments searching for a low ionization signal from sub-GeV dark matter, as there are fewer potential sources of spurious backgrounds. We discuss various target choices, but focus on calculating the expected dark matter-electron scattering rates in three scintillating crystals: sodium iodide (NaI), cesium iodide (CsI), and gallium arsenide (GaAs). Among these, GaAs has the lowest band gap (1.52 eV) compared to NaI (5.9 eV) or CsI (6.4 eV), which in principle allows it to probe dark matter masses as low as ˜0.5 MeV , compared to ˜1.5 MeV with NaI or CsI. We compare these scattering rates with those expected in silicon (Si) and germanium (Ge). The proposed experimental concept presents an important complementary path to existing efforts, and its potential advantages may make it the most sensitive direct-detection probe of dark matter down to MeV masses.

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

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hyo-Min; Choi, Yu-Na; Lee, Seung-Wan; Lee, Young-Jin; Ryu, Hyun-Ju; Kim, Hee-Joung [Yonsei University, Wonju (Korea, Republic of)

    2012-12-15

    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.

  4. Photon counting for quantum key distribution with Peltier cooled InGaAs/InP APD's

    CERN Document Server

    Stucki, D; Stefanov, A; Zbinden, H; Rarity, J G; Wall, T; Stucki, Damien; Ribordy, Gr\\'{e}goire; Stefanov, Andr\\'{e}; Zbinden, Hugo; Rarity, John G.; Wall, Tom

    2001-01-01

    The performance of three types of InGaAs/InP avalanche photodiodes is investigated for photon counting at 1550 nm in the temperature range of thermoelectric cooling. The best one yields a dark count probability of $% 2.8\\cdot 10^{-5}$ per gate (2.4 ns) at a detection efficiency of 10% and a temperature of -60C. The afterpulse probability and the timing jitter are also studied. The results obtained are compared with those of other papers and applied to the simulation of a quantum key distribution system. An error rate of 10% would be obtained after 54 kilometers.

  5. Dear-Mama: A photon counting X-ray imaging project for medical applications

    Science.gov (United States)

    Blanchot, G.; Chmeissani, M.; Díaz, A.; Díaz, F.; Fernández, J.; García, E.; García, J.; Kainberger, F.; Lozano, M.; Maiorino, M.; Martínez, R.; Montagne, J. P.; Moreno, I.; Pellegrini, G.; Puigdengoles, C.; Sentís, M.; Teres, L.; Tortajada, M.; Ullán, M.

    2006-12-01

    Dear-Mama ( Detection of Early Markers in Mammography) is an EU funded project devoted to develop an X-ray Medical imaging device based on room temperature solid-state pixel detector coupled to photon counting readout electronics via bump bonding. The technology being used leads to signal-to-noise ratio enhancement and thus the ability to detect low contrast anomalies such as micro-calcifications. The Dear-Mama machine is currently being evaluated and preliminary results show an excellent MTF response. Dear-Mama consortium is made up from six European institutions, the project runs from December 2001 to March 2006.

  6. Dear-Mama: A photon counting X-ray imaging project for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Blanchot, G. [Institute De Fisica D' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Chmeissani, M. [Institute De Fisica D' Altes Energies, UAB Campus, 08193 Bellaterra (Spain)]. E-mail: mokhtar@ifae.es; Diaz, A. [Sedecal SA, C/ Pelaya 9, Pol. Ind. Rio de Janeiro, 28110 Algete (Spain); Diaz, F. [Sedecal SA, C/ Pelaya 9, Pol. Ind. Rio de Janeiro, 28110 Algete (Spain); Fernandez, J. [UDIAT, Corporacion Sanitaria Parc Tauli, s/n. 08208-Sabadell (Spain); Garcia, E. [Sedecal SA, C/ Pelaya 9, Pol. Ind. Rio de Janeiro, 28110 Algete (Spain); Garcia, J. [Institute De Fisica D' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Kainberger, F. [Medical University of Vienna AKH, A-1090 Vienna (Austria); Lozano, M. [CNM-CSIC, UAB Campus, 08193 Bellaterra (Spain); Maiorino, M. [Institute De Fisica D' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Martinez, R. [CNM-CSIC, UAB Campus, 08193 Bellaterra (Spain); Montagne, J.P. [Hopital D' enfants Armand Trousseau, 75571 Paris Cedex (France); Moreno, I. [Sedecal SA, C/ Pelaya 9, Pol. Ind. Rio de Janeiro, 28110 Algete (Spain); Pellegrini, G. [CNM-CSIC, UAB Campus, 08193 Bellaterra (Spain); Puigdengoles, C. [Institute De Fisica D' Altes Energies, UAB Campus, 08193 Bellaterra (Spain); Sentis, M. [UDIAT, Corporacion Sanitaria Parc Tauli, s/n. 08208-Sabadell (Spain); Teres, L. [CNM-CSIC, UAB Campus, 08193 Bellaterra (Spain); Tortajada, M. [UDIAT, Corporacion Sanitaria Parc Tauli, s/n. 08208-Sabadell (Spain); Ullan, M. [CNM-CSIC, UAB Campus, 08193 Bellaterra (Spain)

    2006-12-10

    Dear-Mama (Detection of Early Markers in Mammography) is an EU funded project devoted to develop an X-ray Medical imaging device based on room temperature solid-state pixel detector coupled to photon counting readout electronics via bump bonding. The technology being used leads to signal-to-noise ratio enhancement and thus the ability to detect low contrast anomalies such as micro-calcifications. The Dear-Mama machine is currently being evaluated and preliminary results show an excellent MTF response. Dear-Mama consortium is made up from six European institutions, the project runs from December 2001 to March 2006.

  7. Detection probabilities for photon-counting avalanche photodiodes applied to a laser radar system.

    Science.gov (United States)

    Henriksson, Markus

    2005-08-20

    Arrays of photon-counting avalanche photodiodes with time-resolved readout can improve the performance of three-dimensional laser radars. A comparison of the detection and false-alarm probabilities for detectors in linear mode and in Geiger mode is shown. With low background radiation their performance is comparable. It is shown that in both cases it will be necessary to process several laser shots of the same scene to improve detection and reduce the false-alarm rate. Additional calculations show that the linear mode detector is much better at detecting targets behind semitransparent obscurations such as vegetation and camouflage nets.

  8. Maximum-likelihood reconstruction of photon returns from simultaneous analog and photon-counting lidar measurements

    CERN Document Server

    Veberic, Darko

    2011-01-01

    We present a novel method for combining the analog and photon-counting measurements of lidar transient recorders into reconstructed photon returns. The method takes into account the statistical properties of the two measurement modes and estimates the most likely number of arriving photons and the most likely values of acquisition parameters describing the two measurement modes. It extends and improves the standard combining ("gluing") methods and does not rely on any ad hoc definitions of the overlap region nor on any ackground subtraction methods.

  9. Photon-counting chip-interleaved iterative PIC detector over atmospheric turbulence channels

    Institute of Scientific and Technical Information of China (English)

    Xiaolin Zhou; Yandong Yang; Yufeng Shao; Jun Liu

    2012-01-01

    A photon-counting-based iterative parallel interference cancellation (PIC) scheme for free-space optical communications in the presence of multiple-access interference,shot noise,background radiation,and turbulence fading is designed.An efficient chip-level iterative equivalent noise estimation algorithm is also derived.Simulation results show that the proposed scheme can achieve a single-user performance,bound with the fast convergence property.More importantly,it can eliminate the bit-error rate floor of the conventional optical code-division multiple-access system with the aid of a relatively short spreading code length.

  10. Relationship between Scattered Photon Counts and Concentrations of Some Saline Solutions in Compton Scattering

    Institute of Scientific and Technical Information of China (English)

    LUO Guang; ZHOU Shang-Qi; HAN Zhong; CHEN Shuang-Kou

    2007-01-01

    Compton scattering saline solution was researched.Firstly according to the Compton scattering theory the linear relationship between the concentration and the scattered photon counts was obtained.And then it was proved by Compton scattering experiments for some solutions.According to those experiments, it was found that the slope was decreased when the atomic number of the cation was increased for alkali metal chloride solutions and alkaline-earth metal chloride solutions.Based on those relationships,a new method was promoted with which to measure the concentration of saline solution untouched the measured solution.

  11. Longitudinal Bunch Pattern Measurements through Single Photon Counting at SPEAR3

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongyi (Jack); /UC, San Diego

    2012-09-07

    The Stanford Synchrotron Radiation Lightsource (SSRL), a division of SLAC National Accelerator Laboratory, is a synchrotron light source that provides x-rays for experimental use. As electrons are bent in the storage ring, they emit electromagnetic radiation. There are 372 different buckets which electrons can be loaded into. Different filling patterns produce different types of x-rays. What is the bunch pattern at a given time? Which filling pattern is better? Are there any flaws to the current injection system? These questions can be answered with this single photon counting experiment.

  12. 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.

  13. Method to simulate the object tracking with photon-counting laser ranging system

    Science.gov (United States)

    Du, Xian; Xing, JiChuan; Huang, Hao

    2015-11-01

    We provide a new method to simulate the process of tracking the noncooperative object that moves beyond visual range with a photon-counting laser ranging system. Based on fundamentals of photon-counting laser ranging techniques and parameters of the experimental prototype, we generate echo events according to their probability. Then, we accumulate the echo data in a certain period of time and accurately extract the object's trajectory with mean-shift and random sample consensus algorithms. Depending on the trajectory during the accumulation period, we predict the relative movement of the object in succeeding cycles by using self-tuning α-β filtering and carefully pick out photon echo signals and apply the polynomial fitting to them to compute the trajectory of the object. The simulation shows that the error between the theoretical trajectory and the extracted trajectory is decreasing all the time, which suggests that we can track the object precisely as the time goes by. The simulation in this paper provides a new way for applications like satellite orientation, identification, troubleshooting, etc.

  14. Photon counting range-intensity image strategy in low-light level environments.

    Science.gov (United States)

    Zhang, Zijing; Xu, Yuannan; Wu, Long; Zhang, Yong; Zhao, Yuan; Su, Jianzhong

    2014-04-15

    We present a photon counting range-intensity image strategy based on a single-photon detector in low-light level environments. In this Letter, a composite modulation method over the pulse sequence was used for the first time, to the best of our knowledge, which combined pulse-position modulation and pulse-intensity modulation. This composite modulation method could obtain range and intensity of the detected target at the same time. Besides, angle-angle information could be provided from the scanner or detector array. Thus, a range-intensity image of the target became feasible. For demonstrating this photon counting range-intensity image strategy, a proof-of-principle laboratory system was established. In low-light level environments, a range-intensity image of multiple similar targets was obtained successfully with the range accuracy of centimeter level and intensity error of 1%. Compared with the range image, a range-intensity image could better reorganize and identify similar targets.

  15. MABEL photon-counting laser altimetry data in Alaska for ICESat-2 simulations and development

    Science.gov (United States)

    Brunt, Kelly M.; Neumann, Thomas A.; Amundson, Jason M.; Kavanaugh, Jeffrey L.; Moussavi, Mahsa S.; Walsh, Kaitlin M.; Cook, William B.; Markus, Thorsten

    2016-08-01

    Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) is scheduled to launch in late 2017 and will carry the Advanced Topographic Laser Altimeter System (ATLAS), which is a photon-counting laser altimeter and represents a new approach to satellite determination of surface elevation. Given the new technology of ATLAS, an airborne instrument, the Multiple Altimeter Beam Experimental Lidar (MABEL), was developed to provide data needed for satellite-algorithm development and ICESat-2 error analysis. MABEL was deployed out of Fairbanks, Alaska, in July 2014 to provide a test dataset for algorithm development in summer conditions with water-saturated snow and ice surfaces. Here we compare MABEL lidar data to in situ observations in Southeast Alaska to assess instrument performance in summer conditions and in the presence of glacier surface melt ponds and a wet snowpack. Results indicate the following: (1) based on MABEL and in situ data comparisons, the ATLAS 90 m beam-spacing strategy will provide a valid assessment of across-track slope that is consistent with shallow slopes (< 1°) of an ice-sheet interior over 50 to 150 m length scales; (2) the dense along-track sampling strategy of photon counting systems can provide crevasse detail; and (3) MABEL 532 nm wavelength light may sample both the surface and subsurface of shallow (approximately 2 m deep) supraglacial melt ponds. The data associated with crevasses and melt ponds indicate the potential ICESat-2 will have for the study of mountain and other small glaciers.

  16. 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...

  17. 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.

  18. Sea-Ice Freeboard Retrieval Using Digital Photon-Counting Laser Altimetry

    Science.gov (United States)

    Farrell, Sinead L.; Brunt, Kelly M.; Ruth, Julia M.; Kuhn, John M.; Connor, Laurence N.; Walsh, Kaitlin M.

    2015-01-01

    Airborne and spaceborne altimeters provide measurements of sea-ice elevation, from which sea-ice freeboard and thickness may be derived. Observations of the Arctic ice pack by satellite altimeters indicate a significant decline in ice thickness, and volume, over the last decade. NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2) is a next-generation laser altimeter designed to continue key sea-ice observations through the end of this decade. An airborne simulator for ICESat-2, the Multiple Altimeter Beam Experimental Lidar (MABEL), has been deployed to gather pre-launch data for mission development. We present an analysis of MABEL data gathered over sea ice in the Greenland Sea and assess the capabilities of photon-counting techniques for sea-ice freeboard retrieval. We compare freeboard estimates in the marginal ice zone derived from MABEL photon-counting data with coincident data collected by a conventional airborne laser altimeter. We find that freeboard estimates agree to within 0.03m in the areas where sea-ice floes were interspersed with wide leads, and to within 0.07m elsewhere. MABEL data may also be used to infer sea-ice thickness, and when compared with coincident but independent ice thickness estimates, MABEL ice thicknesses agreed to within 0.65m or better.

  19. 32-channel single photon counting module for ultrasensitive detection of DNA sequences

    Science.gov (United States)

    Gudkov, Georgiy; Dhulla, Vinit; Borodin, Anatoly; Gavrilov, Dmitri; Stepukhovich, Andrey; Tsupryk, Andrey; Gorbovitski, Boris; Gorfinkel, Vera

    2006-10-01

    We continue our work on the design and implementation of multi-channel single photon detection systems for highly sensitive detection of ultra-weak fluorescence signals, for high-performance, multi-lane DNA sequencing instruments. A fiberized, 32-channel single photon detection (SPD) module based on single photon avalanche diode (SPAD), model C30902S-DTC, from Perkin Elmer Optoelectronics (PKI) has been designed and implemented. Unavailability of high performance, large area SPAD arrays and our desire to design high performance photon counting systems drives us to use individual diodes. Slight modifications in our quenching circuit has doubled the linear range of our system from 1MHz to 2MHz, which is the upper limit for these devices and the maximum saturation count rate has increased to 14 MHz. The detector module comprises of a single board computer PC-104 that enables data visualization, recording, processing, and transfer. Very low dark count (300-1000 counts/s), robust, efficient, simple data collection and processing, ease of connectivity to any other application demanding similar requirements and similar performance results to the best commercially available single photon counting module (SPCM from PKI) are some of the features of this system.

  20. Time transfer capability of standard small form factor pluggable laser modules based on photon counting approach

    Science.gov (United States)

    Trojanek, Pavel; Prochazka, Ivan; Blazej, Josef

    2017-05-01

    We are reporting on timing parameters of commonly used standard Small Form Factor Pluggable (SFP) laser modules using single photon counting method. Photon counting is a promising approach for laser time transfer via optical fiber communication hardware. The sub-picosecond precision and stability may be achieved. We have performed several experiments with the aim to measure main parameters of the modules, such as time delay precision, time stability and temperature stability, all being critical for optical time transfer applications. Two standard 16 and 10 Gbit/s at 850 nm SFP modules were examined. The ultimate precision of possible time transfer of 800 fs for averaging times of hours was achieved. The modules together with their driving circuits exhibited very good temperature stability. The temperature drift as low as 300+/-200 fs/K was measured. The achieved timing parameters will enable to use the standard SFP modules for a new method of two way time transfer where the time differences between two distant time scales are measured in parallel to data transfer on existing optical data links without any communication interference.

  1. 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.

  2. Design and performance of a fiber array coupled multi-channel photon counting, 3D imaging, airborne lidar system

    Science.gov (United States)

    Huang, Genghua; Shu, Rong; Hou, Libing; Li, Ming

    2014-06-01

    Photon counting lidar has an ultra-high sensitivity which can be hundreds even thousands of times higher than the linear detection lidar. It can significantly increase the system's capability of detection rang and imaging density, saving size and power consumings in airborne or space-borne applications. Based on Geiger-mode Si avalanche photodiodes (Si-APD), a prototype photon counting lidar which used 8 APDs coupled with a 1×8-pixel fiber array has been made in June, 2011. The experiments with static objects showed that the photon counting lidar could operate in strong solar background with 0.04 receiving photoelectrons on average. Limited by less counting times in moving platforms, the probability of detection and the 3D imaging density would be lower than that in static platforms. In this paper, a latest fiber array coupled multi-channel photon counting, 3D imaging, airborne lidar system is introduced. The correlation range receiver algorithm of photon counting 3D imaging is improved for airborne signal photon events extraction and noise filter. The 3D imaging experiments in the helicopter shows that the false alarm rate is less than 6×10-7, and the correct rate is better than 99.9% with 4 received photoelectrons and 0.7MHz system noise on average.

  3. 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

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

    Science.gov (United States)

    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.

    2015-07-01

    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 6×1012 1 MeV neq/cm2 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.

  5. Vision 20/20: Single photon counting x-ray detectors in medical imaging.

    Science.gov (United States)

    Taguchi, Katsuyuki; Iwanczyk, Jan S

    2013-10-01

    Photon counting detectors (PCDs) with energy discrimination capabilities have been developed for medical x-ray computed tomography (CT) and x-ray (XR) imaging. Using detection mechanisms that are completely different from the current energy integrating detectors and measuring the material information of the object to be imaged, these PCDs have the potential not only to improve the current CT and XR images, such as dose reduction, but also to open revolutionary novel applications such as molecular CT and XR imaging. The performance of PCDs is not flawless, however, and it seems extremely challenging to develop PCDs with close to ideal characteristics. In this paper, the authors offer our vision for the future of PCD-CT and PCD-XR with the review of the current status and the prediction of (1) detector technologies, (2) imaging technologies, (3) system technologies, and (4) potential clinical benefits with PCDs.

  6. 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.; Bradford, M.

    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.

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

    Science.gov (United States)

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

    2016-09-01

    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.

  8. Experimental Study on Coherence Time of a Light Field with Single Photon Counting

    Institute of Scientific and Technical Information of China (English)

    LI Yuan; ZHANG Yu-Chi; ZHANG Peng-Fei; GUO Yan-Qiang; LI Gang; WANG Jun-Min; ZHANG Tian-Cai

    2009-01-01

    The second-order degree of coherence of pseudo-thermal light and coherence time are experimentally studied via the Hanbruy-Brown-Twiss (HBT) scheme. The system consists of two non-photon-number-resolving single-photon-counting modules (SPCMs) operating in the Geiger mode. We investigate the coherence time of the incident beam for different spot sizes on a ground glass and speeds of a rotating ground glass. The corresponding coherence time can be obtained from Gaussian fitting for the measured second-order degree of coherence. The results show that the coherence time of measured pseudo-thermal fight depends on the spot sizes and the rotating speeds of the ground glass. The maximum value of the second-order degree of coherence is reduced as the rotating speed decreases. This result can be well explained by the model of mixed thermal and coherent fields with different ratios.

  9. 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.

  10. Absolute calibration of an EMCCD camera by quantum correlation, linking photon counting to the analog regime.

    Science.gov (United States)

    Avella, A; Ruo-Berchera, I; Degiovanni, I P; Brida, G; Genovese, M

    2016-04-15

    We show how the same setup and procedure, exploiting spatially multimode quantum correlations, allows the absolute calibration of an electron-multiplying charge-coupled (EMCCD) camera from the analog regime down to the single-photon-counting level, just by adjusting the brightness of the quantum source. At the single-photon level, an EMCCD can be operated as an on-off detector, where quantum efficiency depends on the discriminating threshold. We develop a simple model to explain the connection of the two different regimes demonstrating that the efficiency estimated in the analog (bright) regime allows us to accurately predict the detector behavior in the photocounting regime and vice versa. This work establishes a bridge between two regions of the optical measurements that up to now have been based on completely different standards, detectors, and measurement techniques.

  11. Photon counting chirped amplitude modulation lidar using an asymmetric triangular wave modulation

    Science.gov (United States)

    Zhang, Zijing; Cen, Longzhu; Zhang, Jiandong; Ma, Kun; Wang, Feng; Zhao, Yuan

    2016-11-01

    We propose a novel strategy of asymmetric triangular-wave modulation for photon-counting chirped amplitude modulation (PCCAM) lidar. Earlier studies use the symmetric triangle wave modulation, by which the velocity can be detected only when the Doppler shift caused by a moving target is greater than Full Width Half Maximum (FWHM) of Intermediate Frequency (IF). We use an alternative method known as the asymmetric triangular wave modulation method, in which the modulation rates of the up-ramp and the down-ramp are different. This new method avoids the overlapping of the up-ramp and the down-ramp IF peaks, and breaks the limit of the FWHM of IF peak to improve the velocity measuring sensitivity (also called the minimum detectable velocity). Finally, a proof-of-principle experiment is carried out in the laboratory. The experimental results agree well with the theoretical results and show the improvement of the minimum detectable velocity.

  12. FROST: a low-noise high-rate photon counting ASIC for X-ray applications

    Energy Technology Data Exchange (ETDEWEB)

    Prest, M. E-mail: prest@ts.infn.it; Vallazza, E.; Chiavacci, M.; Mariani, R.; Motto, S.; Neri, M.; Scantamburlo, N.; Arfelli, F.; Conighi, A.; Longo, R.; Olivo, A.; Pani, S.; Poropat, P.; Rashevsky, A.; Rigon, L.; Tromba, G.; Castelli, E

    2001-04-01

    FRONTier RADiography is an R and D project to assess the feasibility of digital mammography with Synchrotron Radiation at the ELETTRA Light Source in Trieste. In order to reach an acceptable time duration of the exam, a fast- and low-noise photon counting ASIC has been developed in collaboration with Aurelia Microelettronica, called Frontrad ReadOut SysTem. It is a multichannel counting system, each channel being made of a low-noise charge-sensitive preamplifier optimized for X-ray energy range (10-100 keV), a CR-RC{sup 2} shaper, a discriminator and a 16-bit counter. In order to set the discriminator threshold, a set of a global 6-bit DAC and a local (per channel) 3-bit DAC has been implemented within the ASIC. We report on the measurements done with the 8-channel prototype chip and the comparison with the simulation results.

  13. 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.

  14. Observer-model optimization of X-ray system in photon-counting breast imaging

    Science.gov (United States)

    Cederström, Björn; Fredenberg, Erik; Lundqvist, Mats; Ericson, Tove; Åslund, Magnus

    2011-08-01

    An ideal-observer model is applied to optimize the design of an X-ray tube intended for use in a multi-slit scanning photon-counting mammography system. The design is such that the anode and the heel effect are reversed and the projected focal spot is smallest at the chest wall. Using linear systems theory, detectability and dose efficiency for a 0.1-mm disk are calculated for different focal spot sizes and anode angles. It is shown that the image acquisition time can be reduced by about 25% with spatial resolution and dose efficiency improved near the chest wall and worsened further away. The image quality is significantly more homogeneous than for the conventional anode orientation, both with respect to noise and detectability of a small object. With the tube rotated 90∘, dose efficiency can be improved by 20% for a fixed image acquisition time.

  15. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

    Manolopoulos, S.; Bates, R.; Campbell, M.; Snoeys, W.; Heijne, E.; Pernigotti, E.; Raine, C.; Smith, K. E-mail: k.smith@physics.gla.ac.uk; Watt, J.; O' Shea, V.; Ludwig, J.; Schwarz, C

    1999-09-11

    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)

  17. Improvement of range accuracy of photon counting chirped AM ladar using phase postprocessing.

    Science.gov (United States)

    Zhang, Zijing; Zhao, Yuan; Zhang, Yong; Wu, Long; Su, Jianzhong

    2013-04-10

    The photon counting detection of Geiger mode avalanche photodiode is discrete due to its dead time, therefore the intermediate frequency (IF) spectrum is also discrete after the mixing and fast Fourier transform processing. When the peak of the IF spectrum is in the interval of the discrete IF spectrum, it limits the range accuracy without obtaining the exact position of the desired target in the interval. In this paper, the phase postprocessing method is proposed, which extracts not only the frequency of the IF signal, but also the phase of the IF signal that was not exploited before. The theoretical analysis demonstrates significant improvements in the range accuracy of the ladar and the simulation verifies the validity of the method.

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

    Energy Technology Data Exchange (ETDEWEB)

    Andreotti, M.; Baldini, W.; Calabrese, R. [Università degli Studi di Ferrara and INFN Sezione di Ferrara (Italy); Carniti, P.; Cassina, L. [Università degli Studi di Milano Bicocca and INFN Sezione di Milano Bicocca (Italy); Cotta Ramusino, A. [Università degli Studi di Ferrara and INFN Sezione di Ferrara (Italy); Fiorini, M., E-mail: fiorini@fe.infn.it [Università degli Studi di Ferrara and INFN Sezione di Ferrara (Italy); Giachero, A.; Gotti, C. [Università degli Studi di Milano Bicocca and INFN Sezione di Milano Bicocca (Italy); Luppi, E. [Università degli Studi di Ferrara and INFN Sezione di Ferrara (Italy); Maino, M. [Università degli Studi di Milano Bicocca and INFN Sezione di Milano Bicocca (Italy); Malaguti, R. [Università degli Studi di Ferrara and INFN Sezione di Ferrara (Italy); Pessina, G. [Università degli Studi di Milano Bicocca and INFN Sezione di Milano Bicocca (Italy); Tomassetti, L. [Università degli Studi di Ferrara and INFN Sezione di Ferrara (Italy)

    2015-07-01

    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{sup 12} 1 MeV n{sub eq}/cm{sup 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.

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

    Science.gov (United States)

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

    2016-06-01

    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.

  20. Continuously scanning time-correlated single-photon-counting single-pixel 3-D lidar

    Science.gov (United States)

    Henriksson, Markus; Larsson, Håkan; Grönwall, Christina; Tolt, Gustav

    2017-03-01

    Time-correlated single-photon-counting (TCSPC) lidar provides very high resolution range measurements. This makes the technology interesting for three-dimensional imaging of complex scenes with targets behind foliage or other obscurations. TCSPC is a statistical method that demands integration of multiple measurements toward the same area to resolve objects at different distances within the instantaneous field-of-view. Point-by-point scanning will demand significant overhead for the movement, increasing the measurement time. Here, the effect of continuously scanning the scene row-by-row is investigated and signal processing methods to transform this into low-noise point clouds are described. The methods are illustrated using measurements of a characterization target and an oak and hazel copse. Steps between different surfaces of less than 5 cm in range are resolved as two surfaces.

  1. 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.

  2. Development of low read noise high conversion gain CMOS image sensor for photon counting level imaging

    Science.gov (United States)

    Seo, Min-Woong; Kawahito, Shoji; Kagawa, Keiichiro; Yasutomi, Keita

    2016-05-01

    A CMOS image sensor with deep sub-electron read noise and high pixel conversion gain has been developed. Its performance is recognized through image outputs from an area image sensor, confirming the capability of photoelectroncounting- level imaging. To achieve high conversion gain, the proposed pixel has special structures to reduce the parasitic capacitances around FD node. As a result, the pixel conversion gain is increased due to the optimized FD node capacitance, and the noise performance is also improved by removing two noise sources from power supply. For the first time, high contrast images from the reset-gate-less CMOS image sensor, with less than 0.3e- rms noise level, have been generated at an extremely low light level of a few electrons per pixel. In addition, the photon-counting capability of the developed CMOS imager is demonstrated by a measurement, photoelectron-counting histogram (PCH).

  3. A dynamic attenuator improves spectral imaging with energy-discriminating, photon counting detectors.

    Science.gov (United States)

    Hsieh, Scott S; Pelc, Norbert J

    2015-03-01

    Energy-discriminating, photon counting (EDPC) detectors have high potential in spectral imaging applications but exhibit degraded performance when the incident count rate approaches or exceeds the characteristic count rate of the detector. In order to reduce the requirements on the detector, we explore the strategy of modulating the X-ray flux field using a recently proposed dynamic, piecewise-linear attenuator. A previous paper studied this modulation for photon counting detectors but did not explore the impact on spectral applications. In this work, we modeled detection with a bipolar triangular pulse shape (Taguchi et al., 2011) and estimated the Cramer-Rao lower bound (CRLB) of the variance of material selective and equivalent monoenergetic images, assuming deterministic errors at high flux could be corrected. We compared different materials for the dynamic attenuator and found that rare earth elements, such as erbium, outperformed previously proposed materials such as iron in spectral imaging. The redistribution of flux reduces the variance or dose, consistent with previous studies on benefits with conventional detectors. Numerical simulations based on DICOM datasets were used to assess the impact of the dynamic attenuator for detectors with several different characteristic count rates. The dynamic attenuator reduced the peak incident count rate by a factor of 4 in the thorax and 44 in the pelvis, and a 10 Mcps/mm (2) EDPC detector with dynamic attenuator provided generally superior image quality to a 100 Mcps/mm (2) detector with reference bowtie filter for the same dose. The improvement is more pronounced in the material images.

  4. 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.

  5. Optimization of Shielded Scintillator for Neutron Detection

    Science.gov (United States)

    Belancourt, Patrick; Morrison, John; Akli, Kramer; Freeman, Richard; High Energy Density Physics Team

    2011-10-01

    The High Energy Density Physics group is interested in the basic science of creating a neutron and gamma ray source. The neutrons and gamma rays are produced by accelerating ions via a laser into a target and creating fusion neutrons and gamma rays. A scintillator and photomultiplier tube will be used to detect these neutrons. Neutrons and photons produce ionizing radiation in the scintillator which then activates metastable states. These metastable states have both short and long decay rates. The initial photon count is orders of magnitude higher than the neutron count and poses problems for accurately detecting the neutrons due to the long decay state that is activated by the photons. The effects of adding lead shielding on the temporal response and signal level of the neutron detector will be studied in an effort to minimize the photon count without significant reduction to the temporal resolution of the detector. MCNP5 will be used to find the temporal response and energy deposition into the scintillator by adding lead shielding. Results from the simulations will be shown. Optimization of our scintillator neutron detection system is needed to resolve the neutron energies and neutron count of a novel neutron and gamma ray source.

  6. Novel approaches to address spectral distortions in photon counting x-ray CT using artificial neural networks

    Science.gov (United States)

    Touch, M.; Clark, D. P.; Barber, W.; Badea, C. T.

    2016-04-01

    Spectral CT using a photon-counting x-ray detector (PCXD) can potentially increase accuracy of measuring tissue composition. However, PCXD spectral measurements suffer from distortion due to charge sharing, pulse pileup, and Kescape energy loss. This study proposes two novel artificial neural network (ANN)-based algorithms: one to model and compensate for the distortion, and another one to directly correct for the distortion. The ANN-based distortion model was obtained by training to learn the distortion from a set of projections with a calibration scan. The ANN distortion was then applied in the forward statistical model to compensate for distortion in the projection decomposition. ANN was also used to learn to correct distortions directly in projections. The resulting corrected projections were used for reconstructing the image, denoising via joint bilateral filtration, and decomposition into three-material basis functions: Compton scattering, the photoelectric effect, and iodine. The ANN-based distortion model proved to be more robust to noise and worked better compared to using an imperfect parametric distortion model. In the presence of noise, the mean relative errors in iodine concentration estimation were 11.82% (ANN distortion model) and 16.72% (parametric model). With distortion correction, the mean relative error in iodine concentration estimation was improved by 50% over direct decomposition from distorted data. With our joint bilateral filtration, the resulting material image quality and iodine detectability as defined by the contrast-to-noise ratio were greatly enhanced allowing iodine concentrations as low as 2 mg/ml to be detected. Future work will be dedicated to experimental evaluation of our ANN-based methods using 3D-printed phantoms.

  7. 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.

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

    Science.gov (United States)

    Kalender, W

    2016-06-01

    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. In

  9. Comparative investigation of the detective quantum efficiency of direct and indirect conversion detector technologies in dedicated breast CT.

    Science.gov (United States)

    Kuttig, Jan D; Steiding, Christian; Kolditz, Daniel; Hupfer, Martin; Karolczak, Marek; Kalender, Willi A

    2015-06-01

    To investigate the dose saving potential of direct-converting CdTe photon-counting detector technology for dedicated breast CT. We analyzed the modulation transfer function (MTF), the noise power spectrum (NPS) and the detective quantum efficiency (DQE) of two detector technologies, suitable for breast CT (BCT): a flat-panel energy-integrating detector with a 70 μm and a 208 μm thick gadolinium oxysulfide (GOS) and a 150 μm thick cesium iodide (CsI) scintillator and a photon-counting detector with a 1000 μm thick CdTe sensor. The measurements for GOS scintillator thicknesses of 70 μm and 208 μm delivered 10% pre-sampled MTF values of 6.6 mm(-1) and 3.2 mm(-1), and DQE(0) values of 23% and 61%. The 10% pre-sampled MTF value for the 150 μm thick CsI scintillator 6.9 mm(-1), and the DQE(0) value was 49%. The CdTe sensor reached a 10% pre-sampled MTF value of 8.5 mm(-1) and a DQE(0) value of 85%. The photon-counting CdTe detector technology allows for significant dose reduction compared to the energy-integrating scintillation detector technology used in BCT today. Our comparative evaluation indicates that a high potential dose saving may be possible for BCT by using CdTe detectors, without loss of spatial resolution. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  10. Photon-counting Brillouin optical time-domain reflectometry based on up-conversion detector and fiber Fabry-Perot scanning interferometer

    CERN Document Server

    Xia, Haiyun; Shentu, Guoliang; Wang, Chong; Qiu, Jiawei; Xia, Xiuxiu; Chen, Chao; Zheng, Mingyang; Xie, Xiuping; Zhang, Qiang; Dou, Xiankang; Pan, Jianwei

    2015-01-01

    A direct-detection Brillouin optical time-domain reflectometry (BOTDR) is proposed and demonstrated by using an up-conversion single-photon detector and a fiber Fabry-Perot scanning interferometer (FFP-SI). Taking advantage of high signal-to-noise ratio of the detector and high spectrum resolution of the FFP-SI, the Brillouin spectrum along a polarization maintaining fiber (PMF) is recorded on a multiscaler with a small data size directly. In contrast with conventional BOTDR adopting coherent detection, photon-counting BOTDR is simpler in structure and easier in data processing. In the demonstration experiment, characteristic parameters of the Brillouin spectrum including its power, spectral width and frequency center are analyzed simultaneously along a 10 km PMF at different temperature and stain conditions.

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

    Science.gov (United States)

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

    2014-09-21

    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

  12. 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

  13. ERICA: an energy resolving photon counting readout ASIC for X-ray in-line cameras

    Science.gov (United States)

    Macias-Montero, J.-G.; Sarraj, M.; Chmeissani, M.; Moore, T.; Casanova, R.; Martinez, R.; Puigdengoles, C.; Prats, X.; Kolstein, M.

    2016-12-01

    We present ERICA (Energy Resolving Inline X-ray Camera) a photon-counting readout ASIC, with 6 energy bins. The ASIC is composed of a matrix of 8 × 20 pixels controlled by a global digital controller and biased with 7 independent digital to analog converters (DACs) and a band-gap current reference. The pixel analog front-end includes a charge sensitive amplifier with 16 mV/ke- gain and dynamic range of 45 ke-. ERICA has programmable pulse width, an adjustable constant current feedback resistor, a linear test pulse generator, and six discriminators with 6-bit local threshold adjustment. The pixel digital back-end includes the digital controller, 8 counters of 8-bit depth, half-full buffer flag for any of the 8 counters, a 74-bit shadow/shift register, a 74-bit configuration latch, and charge sharing compensation processing to perform the energy classification and counting operations of every detected photon in 1 μ s. The pixel size is 330 μm × 330 μm and its average consumption is 150 μW. Implemented in TSMC 0.25 μm CMOS process, the ASIC pixel's equivalent noise charge (ENC) is 90 e- RMS connected to a 1 mm thickness matching CdTe detector biased at -300 V with a total leakage current of 20 nA.

  14. A space- and time-resolved single photon counting detector for fluorescence microscopy and spectroscopy

    Science.gov (United States)

    Michalet, X.; Siegmund, O. H. W.; Vallerga, J. V.; Jelinsky, P.; Millaud, J. E.; Weiss, S.

    2006-02-01

    We have recently developed a wide-field photon-counting detector having high-temporal and high-spatial resolutions and capable of high-throughput (the H33D detector). Its design is based on a 25 mm diameter multi-alkali photocathode producing one photo electron per detected photon, which are then multiplied up to 10 7 times by a 3-microchannel plate stack. The resulting electron cloud is proximity focused on a cross delay line anode, which allows determining the incident photon position with high accuracy. The imaging and fluorescence lifetime measurement performances of the H33D detector installed on a standard epifluorescence microscope will be presented. We compare them to those of standard single-molecule detectors such as single-photon avalanche photodiode (SPAD) or electron-multiplying camera using model samples (fluorescent beads, quantum dots and live cells). Finally, we discuss the design and applications of future generation of H33D detectors for single-molecule imaging and high-throughput study of biomolecular interactions.

  15. Spectral prior image constrained compressed sensing (spectral PICCS) for photon-counting computed tomography

    Science.gov (United States)

    Yu, Zhicong; Leng, Shuai; Li, Zhoubo; McCollough, Cynthia H.

    2016-09-01

    Photon-counting computed tomography (PCCT) is an emerging imaging technique that enables multi-energy imaging with only a single scan acquisition. To enable multi-energy imaging, the detected photons corresponding to the full x-ray spectrum are divided into several subgroups of bin data that correspond to narrower energy windows. Consequently, noise in each energy bin increases compared to the full-spectrum data. This work proposes an iterative reconstruction algorithm for noise suppression in the narrower energy bins used in PCCT imaging. The algorithm is based on the framework of prior image constrained compressed sensing (PICCS) and is called spectral PICCS; it uses the full-spectrum image reconstructed using conventional filtered back-projection as the prior image. The spectral PICCS algorithm is implemented using a constrained optimization scheme with adaptive iterative step sizes such that only two tuning parameters are required in most cases. The algorithm was first evaluated using computer simulations, and then validated by both physical phantoms and in vivo swine studies using a research PCCT system. Results from both computer-simulation and experimental studies showed substantial image noise reduction in narrow energy bins (43-73%) without sacrificing CT number accuracy or spatial resolution.

  16. CLARO-CMOS, a very low power ASIC for fast photon counting with pixellated photodetectors

    Science.gov (United States)

    Carniti, P.; De Matteis, M.; Giachero, A.; Gotti, C.; Maino, M.; Pessina, G.

    2012-11-01

    The CLARO-CMOS is an application specific integrated circuit (ASIC) designed for fast photon counting with pixellated photodetectors such as multi-anode photomultiplier tubes (Ma-PMT), micro-channel plates (MCP), and silicon photomultipliers (SiPM). The first prototype has four channels, each with a charge sensitive amplifier with settable gain and a discriminator with settable threshold, providing fast hit information for each channel independently. The design was realized in a long-established, stable and inexpensive 0.35 μm CMOS technology, and provides outstanding performance in terms of speed and power dissipation. The prototype consumes less than 1 mW per channel at low rate, and less than 2 mW at an event rate of 10 MHz per channel. The recovery time after each pulse is less than 25 ns for input signals within a factor of 10 above threshold. Input referred RMS noise is about 7.7 ke- (1.2 fC) with an input capacitance of 3.3 pF. With this value of input capacitance a timing resolution down to 10 ps RMS was measured for pulser signals of a few million electrons, corresponding to the single photon response for these detectors.

  17. CLARO-CMOS, a very low power ASIC for fast photon counting with pixellated photodetectors

    CERN Document Server

    Carniti, Paolo

    2012-01-01

    The CLARO-CMOS is an application specific integrated circuit (ASIC) designed for fast photon counting with pixellated photodetectors such as multi-anode photomultiplier tubes (Ma-PMT), micro-channel plates (MCP), and silicon photomultipliers (SiPM). The first prototype has four channels, each with a charge sensitive amplifier with settable gain and a discriminator with settable threshold, providing fast hit information for each channel independently. The design was realized in a long-established, stable and inexpensive 0.35 um CMOS technology, and provides outstanding performance in terms of speed and power dissipation. The prototype consumes less than 1 mW per channel at low rate, and less than 2 mW at an event rate of 10 MHz per channel. The recovery time after each pulse is less than 25 ns for input signals within a factor of 10 above threshold. Input referred RMS noise is about 7.7 ke^- (1.2 fC) with an input capacitance of 3.3 pF. Thanks to the low noise and high speed, a timing resolution down to 10 ps ...

  18. Evaluation of models of spectral distortions in photon-counting detectors for computed tomography.

    Science.gov (United States)

    Cammin, Jochen; Kappler, Steffen; Weidinger, Thomas; Taguchi, Katsuyuki

    2016-04-01

    A semi-analytical model describing spectral distortions in photon-counting detectors (PCDs) for clinical computed tomography was evaluated using simulated data. The distortions were due to count rate-independent spectral response effects and count rate-dependent pulse-pileup effects and the model predicted both the mean count rates and the spectral shape. The model parameters were calculated using calibration data. The model was evaluated by comparing the predicted x-ray spectra to Monte Carlo simulations of a PCD at various count rates. The data-model agreement expressed as weighted coefficient of variation [Formula: see text] was better than [Formula: see text] for dead time losses up to 28% and [Formula: see text] or smaller for dead time losses up to 69%. The accuracy of the model was also tested for the purpose of material decomposition by estimating material thicknesses from simulated projection data. The estimated attenuator thicknesses generally agreed with the true values within one standard deviation of the statistical uncertainty obtained from multiple noise realizations.

  19. 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.

  20. Photon efficiency optimization in time-correlated single photon counting technique for fluorescence lifetime imaging systems.

    Science.gov (United States)

    Turgeman, Lior; Fixler, Dror

    2013-06-01

    In time-correlated single photon counting (TCSPC) systems, the maximum signal throughput is limited by the occurrence of pile-up and other effects. In many biological applications that exhibit high levels of fluorescence intensity (FI), pile-up-related distortions yield serious distortions in the fluorescence lifetime (FLT) calculation as well as significant decrease in the signal-to-noise ratio (SNR). Recent developments that allow the use of high-repetition-rate light sources (in the range of 50-100 MHz) in fluorescence lifetime imaging (FLIM) experiments enable minimization of pile-up-related distortions. However, modern TCSPC configurations that use high-repetition-rate excitation sources for FLIM suffer from dead-time-related distortions that cause unpredictable distortions of the FI signal. In this study, the loss of SNR is described by F- value as it is typically done in FLIM systems. This F-value describes the relation of the relative standard deviation in the estimated FLT to the relative standard deviation in FI measurements. Optimization of the F-value allows minimization of signal distortion, as well as shortening of the acquisition time for certain samples. We applied this method for Fluorescein, Rhodamine B, and Erythrosine fluorescent solutions that have different FLT values (4 ns, 1.67 ns, and 140 ps, respectively).

  1. Count rate performance of a silicon-strip detector for photon-counting spectral CT

    Science.gov (United States)

    Liu, X.; Grönberg, F.; Sjölin, M.; Karlsson, S.; Danielsson, M.

    2016-08-01

    A silicon-strip detector is developed for spectral computed tomography. The detector operates in photon-counting mode and allows pulse-height discrimination with 8 adjustable energy bins. In this work, we evaluate the count-rate performance of the detector in a clinical CT environment. The output counts of the detector are measured for x-ray tube currents up to 500 mA at 120 kV tube voltage, which produces a maximum photon flux of 485 Mphotons/s/mm2 for the unattenuated beam. The corresponding maximum count-rate loss of the detector is around 30% and there are no saturation effects. A near linear relationship between the input and output count rates can be observed up to 90 Mcps/mm2, at which point only 3% of the input counts are lost. This means that the loss in the diagnostically relevant count-rate region is negligible. A semi-nonparalyzable dead-time model is used to describe the count-rate performance of the detector, which shows a good agreement with the measured data. The nonparalyzable dead time τn for 150 evaluated detector elements is estimated to be 20.2±5.2 ns.

  2. 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Taguchi, K. [Johns Hopkins University (United States)

    2015-06-15

    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.

  4. 32-channel time-correlated-single-photon-counting system for high-throughput lifetime imaging

    Science.gov (United States)

    Peronio, P.; Labanca, I.; Acconcia, G.; Ruggeri, A.; Lavdas, A. A.; Hicks, A. A.; Pramstaller, P. P.; Ghioni, M.; Rech, I.

    2017-08-01

    Time-Correlated Single Photon Counting (TCSPC) is a very efficient technique for measuring weak and fast optical signals, but it is mainly limited by the relatively "long" measurement time. Multichannel systems have been developed in recent years aiming to overcome this limitation by managing several detectors or TCSPC devices in parallel. Nevertheless, if we look at state-of-the-art systems, there is still a strong trade-off between the parallelism level and performance: the higher the number of channels, the poorer the performance. In 2013, we presented a complete and compact 32 × 1 TCSPC system, composed of an array of 32 single-photon avalanche diodes connected to 32 time-to-amplitude converters, which showed that it was possible to overcome the existing trade-off. In this paper, we present an evolution of the previous work that is conceived for high-throughput fluorescence lifetime imaging microscopy. This application can be addressed by the new system thanks to a centralized logic, fast data management and an interface to a microscope. The new conceived hardware structure is presented, as well as the firmware developed to manage the operation of the module. Finally, preliminary results, obtained from the practical application of the technology, are shown to validate the developed system.

  5. Low-dose lung cancer screening with photon-counting CT: a feasibility study

    Science.gov (United States)

    Symons, Rolf; Cork, Tyler E.; Sahbaee, Pooyan; Fuld, Matthew K.; Kappler, Steffen; Folio, Les R.; Bluemke, David A.; Pourmorteza, Amir

    2017-01-01

    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. Radiation dose-matched EID and PCD scans of the COPDGene 2 phantom 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). EID and PCD images were compared for quantitative Hounsfield unit (HU) accuracy, noise levels, and contrast-to-noise ratios (CNR) for detection of ground-glass nodules (GGN) and emphysema. The PCD HU accuracy was better than EID for water at all scan parameters. PCD HU stability for lung, GGN and emphysema regions were superior to EID and PCD attenuation values were more reproducible than EID for all scan parameters (all P  lung, GGN and emphysema ROIs changed significantly for EID with decreasing dose (all P  lung, ground-glass, and emphysema-equivalent foams at lower radiation dose settings with better reproducibility than EID. Additionally, PCD showed up to 10% less noise, and 11% 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.

  6. A novel micro-pulse laser active imaging method based on photon counting scheme

    Science.gov (United States)

    Liu, Chenghao; Yin, Wenye; Miao, Zhuang; He, Wei-ji; Chen, Qian; Gu, Guo-Hua

    2013-12-01

    We present the use and characterization of a Single Photon Detector (SPD) for active micro-pulse laser imaging. Laser active imaging technology obtains the two dimensional (2D) intensity information of objects by using the active continuous or pulsed laser illumination and an image sensor array. The Maximum range of laser active imaging is limited by the performance of image sensor, whose noise can seriously lower the obtainable SNR and degrade the quality of the reconstructed image. This paper presents a photon counting scheme based micro-pulse laser active imaging method that utilizes the SPD as the receiver and the micro-pulsed laser as the source. In this case, SPD was used to detect the laser echo. By using repeated multi-cycle detection strategies, every detected photon event is treated as an independent measurement of laser echo and thus the intensity information of objects is acquired with the response possibility estimation of laser echo. We chose a Geiger-Mode Avalanche Photodiodes (GM-APD) based approach, extending the methods of micro-pulse laser active imaging. In our implement, the number of TTL pulses output from the GM-APD within the duration of the pixel dwell time was recorder by a LabView pre-programmed instrument and then the laser echo response possibility of GM-APD was established by Full Waveform Analysis algorithm. This approach combined remote imaging with single photon sensitivity and laser active imaging.

  7. High-speed readout solution for single-photon counting ASICs

    Science.gov (United States)

    Kmon, P.; Szczygiel, R.; Maj, P.; Grybos, P.; Kleczek, R.

    2016-02-01

    We report on the analysis, simulations and measurements of both noise and high-count rate performance of a single photon counting integrated circuit called UFXC32k designed for hybrid pixel detectors for various applications in X-ray imaging. The dimensions of the UFCX32k designed in CMOS 130 nm technology are 9.63 mm × 20.15 mm. The integrated circuit core is a matrix of 128 × 256 squared readout pixels with a pitch of 75 μm. Each readout pixel contains a charge sensitive amplifier (CSA), a shaper, two discriminators and two 14-bit ripple counters. The UFXC32k was bump-bonded to a silicon pixel detector with the thickness of 320 μm and characterized with the X-ray radiation source. The CSA feedback based on the Krummenacher circuit determines both the count rate performance and the noise of the readout front-end electronics. For the default setting of the CSA feedback, the measured front-end electronics dead time is 232 ns (paralyzable model) and the equivalent noise charge (ENC) is equal to 123 el. rms. For the high count rate setting of the CSA feedback, the dead time is only 101 ns and the ENC is equal to 163 el. rms.

  8. Antimonide-based Geiger-mode avalanche photodiodes for SWIR and MWIR photon counting

    Science.gov (United States)

    Duerr, Erik K.; Manfra, Michael J.; Diagne, Mohamed A.; Bailey, Robert J.; Zayhowski, John J.; Donnelly, Joseph P.; Connors, Michael K.; Grzesik, Michael J.; Turner, George W.

    2010-04-01

    At MIT Lincoln Laboratory, avalanche photodiodes (APDs) have been developed for both 2-μm and 3.4-μm detection using the antimonide material system. These bulk, lattice-matched detectors operate in Geiger mode at temperatures up to 160 K. The 2-μm APDs use a separate-absorber-multiplier design with an InGaAsSb absorber and electron-initiated avalanching in the multiplier. These APDs have exhibited normalized avalanche probability (product of avalanche probability and photo-carrier-injection probability) of 0.4 and dark count rates of ~150 kHz at 77 K for a 30-μm-diameter device. A 1000- element imaging array of the 2-μm detectors has been demonstrated, which operate in a 5 kg dewar with an integrated Stirling-cycle cooler. The APD array is interfaced with a CMOS readout circuit, which provides photon time-of-arrival information for each pixel, allowing the focal plane array to be used in a photon-counting laser radar system. The 3.4-μm APDs use an InAsSb absorber and hole-initiated avalanching and have shown dark count rates of ~500 kHz at 77 K but normalized avalanche probability of < 1%. Research is ongoing to determine the cause of the low avalanche probability and improve the device performance.

  9. Photon-counting X-ray imaging at kilohertz frame rates

    CERN Document Server

    Ponchut, Cyril; Rigal, J M; Papillon, E; Vallerga, J; LaMarra, D; Mikulec, B

    2007-01-01

    A kilohertz frame rate readout system for Medipix2 chips is being developed at European Synchrotron Radiation Facility (ESRF). This work was initiated with the aim of meeting the growing demand for fast and noise-free X-ray bidimensional detection particularly on synchrotron beamlines. Medipix2 is a photon-counting readout ASIC of 256×256 pixels with 55 μm pitch developed in the framework of the Medipix collaboration managed by CERN. The ESRF readout system is based on a custom interface board named Parallel Readout Image Acquisition for Medipix (PRIAM) a fast PCI interface and a Linux PC. The PRIAM board implementing fast FIFOs and a programmable gate array can read up to five Medipix2 circuits simultaneously in less than 0.3 ms using the 32-bit parallel readout port of Medipix2 and 100 MHz clock frequency. This paper describes the architecture of the PRIAM board, reports on the first test results, and mentions some of the targeted applications.

  10. 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 (...

  11. 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.

  12. Development of a high-performance multichannel system for time-correlated single photon counting

    Science.gov (United States)

    Peronio, P.; Cominelli, A.; Acconcia, G.; Rech, I.; Ghioni, M.

    2017-05-01

    Time-Correlated Single Photon Counting (TCSPC) is one of the most effective techniques for measuring weak and fast optical signals. It outperforms traditional "analog" techniques due to its high sensitivity along with high temporal resolution. Despite those significant advantages, a main drawback still exists, which is related to the long acquisition time needed to perform a measurement. In past years many TCSPC systems have been developed with higher and higher number of channels, aimed to dealing with that limitation. Nevertheless, modern systems suffer from a strong trade-off between parallelism level and performance: the higher the number of channels the poorer the performance. In this work we present the design of a 32x32 TCSPC system meant for overtaking the existing trade-off. To this aim different technologies has been employed, to get the best performance both from detectors and sensing circuits. The exploitation of different technologies will be enabled by Through Silicon Vias (TSVs) which will be investigated as a possible solution for connecting the detectors to the sensing circuits. When dealing with a high number of channels, the count rate is inevitably set by the affordable throughput to the external PC. We targeted a throughput of 10Gb/s, which is beyond the state of the art, and designed the number of TCSPC channels accordingly. A dynamic-routing logic will connect the detectors to the lower number of acquisition chains.

  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. Table-top phase-contrast imaging employing photon-counting detectors towards mammographic applications

    Science.gov (United States)

    Palma, K. D.; Pichotka, M.; Hasn, S.; Granja, C.

    2017-02-01

    In mammography the difficult task to detect microcalcifications (≈ 100 μm) and low contrast structures in the breast has been a topic of interest from its beginnings. The possibility to improve the image quality requires the effort to employ novel X-ray imaging techniques, such as phase-contrast, and high resolution detectors. Phase-contrast techniques are promising tools for medical diagnosis because they provide additional and complementary information to traditional absorption-based X-ray imaging methods. In this work a Hamamatsu microfocus X-ray source with tungsten anode and a photon counting detector (Timepix operated in Medipix mode) was used. A significant improvement in the detection of phase-effects using Medipix detector was observed in comparison to an standard flat-panel detector. An optimization of geometrical parameters reveals the dependency on the X-ray propagation path and the small angle deviation. The quantification of these effects was achieved taking into account the image noise, contrast, spatial resolution of the phase-enhancement, absorbed dose, and energy dependence.

  15. Optimizing ZnS/6LiF scintillators for wavelength-shifting-fiber neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Crow, Lowell [ORNL; Funk, Loren L [ORNL; Hannan, Bruce W [ORNL; Hodges, Jason P [ORNL; Riedel, Richard A [ORNL; Wang, Cai-Lin [ORNL

    2016-01-01

    In this paper we compare the performance of grooved and flat ZnS/6LiF scintillators in a wavelength shifting-fiber (WLSF) detector. Flat ZnS/6LiF scintillators with the thickness L=0.2-0.8 mm were characterized using photon counting and pulse-height analysis and compared to a grooved scintillator of approximately 0.8 mm thick. While a grooved scintillator considerably increases the apparent thickness of the scintillator to neutrons for a given coating thickness, we find that the flat scintillators perform better than the grooved scintillators in terms of both light yield and neutron detection efficiency. The flat 0.8-mm-thick scintillator has the highest light output, and it is 52% higher compared with a grooved scintillator of same thickness. The lower light output of the grooved scintillator as compared to the flat scintillator is consistent with the greater scintillator-WLSF separation and the much larger average emission angle of the grooved scintillator. We also find that the average light cone width, or photon travel-length as measured using time-of-flight powder diffraction of diamond and vanadium, decreases with increasing L in the range of L=0.6-0.8 mm. This result contrasts with the traditional Swank diffusion model for micro-composite scintillators, and could be explained by a decrease in photon diffusion-coefficient or an increase in micro-particle content in the flat scintillator matrix for the thicker scintillators.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seungwan, E-mail: lswan@yonsei.ac.kr; Choi, Yu-Na; Kim, Hee-Joung, E-mail: hjk1@yonsei.ac.kr

    2013-10-21

    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.

  17. Effect of x-ray incident direction and scintillator layer design on image quality of indirect-conversion flat-panel detector with GOS phosphor

    Science.gov (United States)

    Sato, K.; Nariyuki, F.; Nomura, H.; Takasu, A.; Fukui, S.; Nakatsu, M.; Okada, Y.; Nabeta, T.; Hosoi, Y.

    2011-03-01

    In this study, we characterized the image quality of two types of indirect-conversion flat-panel detectors: an X-ray incident-side photo-detection system (IS) and an X-ray penetration-side photo-detection system (PS). These detectors consist of a Gd2O2S:Tb (GOS) scintillator coupled with a photodiode thin film transistor (PD-TFT) array on a glass substrate. The detectors have different X-ray incident directions, glass substrates, and scintillators. We also characterized the effects of layered scintillator structures on the image quality by using a single-layered scintillator containing large phosphor grains and a double-layered scintillator consisting of a layer of large phosphor grains and a layer of small phosphor grains. The IS system consistently demonstrated a higher MTF than the PS system for a scintillator of the same thickness. Moreover, the IS system showed a higher DQE than the PS system when a thick scintillator was used. While the double-layered scintillators were useful for improving the MTF in both systems, a thick single-layered scintillator was preferable for obtaining a high DQE when the IS system was applied. These results indicate that an IS system can efficiently utilize the light emitted from the phosphor at the far side of the PD without the occurrence of blurring. The use of IS systems makes it possible to increase the thickness of the scintillator layer for improving the sensitivity without reducing the MTF, which increases the DQE. The DQE of the IS system was 1.2 times that of the PS system, despite the absorption of X-rays at the glass substrate before entering the phosphor.

  18. Spectral X-Ray CT Image Reconstruction with a Combination of Energy-Integrating and Photon-Counting Detectors.

    Directory of Open Access Journals (Sweden)

    Qingsong Yang

    Full Text Available The purpose of this paper is to develop an algorithm for hybrid spectral computed tomography (CT which combines energy-integrating and photon-counting detectors. While the energy-integrating scan is global, the photon-counting scan can have a local field of view (FOV. The algorithm synthesizes both spectral data and energy-integrating data. Low rank and sparsity prior is used for spectral CT reconstruction. An initial estimation is obtained from the projection data based on physical principles of x-ray interaction with the matter, which provides a more accurate Taylor expansion than previous work and can guarantee the convergence of the algorithm. Numerical simulation with clinical CT images are performed. The proposed algorithm produces very good spectral features outside the FOV when no K-edge material exists. Exterior reconstruction of K-edge material can be partially achieved.

  19. Spectral X-Ray CT Image Reconstruction with a Combination of Energy-Integrating and Photon-Counting Detectors.

    Science.gov (United States)

    Yang, Qingsong; Cong, Wenxiang; Xi, Yan; Wang, Ge

    2016-01-01

    The purpose of this paper is to develop an algorithm for hybrid spectral computed tomography (CT) which combines energy-integrating and photon-counting detectors. While the energy-integrating scan is global, the photon-counting scan can have a local field of view (FOV). The algorithm synthesizes both spectral data and energy-integrating data. Low rank and sparsity prior is used for spectral CT reconstruction. An initial estimation is obtained from the projection data based on physical principles of x-ray interaction with the matter, which provides a more accurate Taylor expansion than previous work and can guarantee the convergence of the algorithm. Numerical simulation with clinical CT images are performed. The proposed algorithm produces very good spectral features outside the FOV when no K-edge material exists. Exterior reconstruction of K-edge material can be partially achieved.

  20. Double-random-phase encryption with photon counting for image authentication using only the amplitude of the encrypted image.

    Science.gov (United States)

    Wang, Yong; Markman, Adam; Quan, Chenggen; Javidi, Bahram

    2016-11-01

    We present a photon-counting double-random-phase encryption technique that only requires the photon-limited amplitude of the encrypted image for decryption. The double-random-phase encryption is used to encrypt an image, generating a complex image. Photon counting is applied to the amplitude of the encrypted image, generating a sparse noise-like image; however, the phase information is not retained. By not using the phase information, the encryption process is simplified, allowing for intensity detection and also less information to be recorded. Using a phase numerically generated from the correct encryption keys together with the photon-limited amplitude of the encrypted image, we are able to decrypt the image. Moreover, nonlinear correlation algorithms can be used to authenticate the decrypted image. Both amplitude-based and full-phase encryption using the proposed method are investigated. Preliminary computational results and performance evaluation are presented.

  1. Multi-Material Decomposition using Low-Current X-Ray and a Photon-Counting CZT Detector.

    Science.gov (United States)

    Kim, Sangtaek; Hernandez, Andrew; Alhassen, Fares; Pivovaroff, Michael; Cho, Hyo-Min; Gould, Robert G; Seo, Youngho

    2011-01-01

    We developed and evaluated an x-ray photon-counting imaging system using an energy-resolving cadmium zinc telluride (CZT) detector coupled with application specific integrated circuit (ASIC) readouts. This x-ray imaging system can be used to identify different materials inside the object. The CZT detector has a large active area (5×5 array of 25 CZT modules, each with 16×16 pixels, cover a total area of 200 mm × 200 mm), high stopping efficiency for x-ray photons (~ 100 % at 60 keV and 5 mm thickness). We explored the performance of this system by applying different energy windows around the absorption edges of target materials, silver and indium, in order to distinguish one material from another. The photon-counting CZT-based x-ray imaging system was able to distinguish between the materials, demonstrating its capability as a radiation-spectroscopic decomposition system.

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

    Science.gov (United States)

    Lee, Daehee; Park, Kyungjin; Lim, Kyung Taek; Cho, Gyuseong

    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 μm2 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.

  3. Depth imaging in highly scattering underwater environments using time-correlated single-photon counting

    Science.gov (United States)

    Maccarone, Aurora; McCarthy, Aongus; Halimi, Abderrahim; Tobin, Rachael; Wallace, Andy M.; Petillot, Yvan; McLaughlin, Steve; Buller, Gerald S.

    2016-10-01

    This paper presents an optical depth imaging system optimized for highly scattering environments such as underwater. The system is based on the time-correlated single-photon counting (TCSPC) technique and the time-of-flight approach. Laboratory-based measurements demonstrate the potential of underwater depth imaging, with specific attention given to environments with a high level of scattering. The optical system comprised a monostatic transceiver unit, a fiber-coupled supercontinuum laser source with a wavelength tunable acousto-optic filter (AOTF), and a fiber-coupled single-element silicon single-photon avalanche diode (SPAD) detector. In the optical system, the transmit and receive channels in the transceiver unit were overlapped in a coaxial optical configuration. The targets were placed in a 1.75 meter long tank, and raster scanned using two galvo-mirrors. Laboratory-based experiments demonstrate depth profiling performed with up to nine attenuation lengths between the transceiver and target. All of the measurements were taken with an average laser power of less than 1mW. Initially, the data was processed using a straightforward pixel-wise cross-correlation of the return timing signal with the system instrumental timing response. More advanced algorithms were then used to process these cross-correlation results. These results illustrate the potential for the reconstruction of images in highly scattering environments, and to permit the investigation of much shorter acquisition time scans. These algorithms take advantage of the data sparseness under the Discrete Cosine Transform (DCT) and the correlation between adjacent pixels, to restore the depth and reflectivity images.

  4. Arterial wall perfusion measured with photon counting spectral x-ray CT

    Science.gov (United States)

    Jorgensen, Steven M.; Korinek, Mark J.; Vercnocke, Andrew J.; Anderson, Jill L.; Halaweish, Ahmed; Leng, Shuai; McCollough, Cynthia H.; Ritman, Erik L.

    2016-10-01

    Early atherosclerosis changes perfusion of the arterial wall due to localized proliferation of the vasa vasorum. When contrast agent passes through the artery, some enters the vasa vasorum and increases radiopacity of the arterial wall. Technical challenges to detecting changes in vasa vasorum density include the thin arterial wall, partial volume averaging at the arterial lumen/wall interface and calcification within the wall. We used a photon-counting spectral CT scanner to study carotid arteries of anesthetized pigs and micro-CT of these arteries to quantify vasa vasorum density. The left carotid artery wall was injected with autologous blood to stimulate vasa vasorum angiogenesis. The scans were performed at 25-120 keV; the tube-current-time product was 550 mAs. A 60 mL bolus of iodine contrast agent was injected into the femoral vein at 5mL/s. Two seconds post injection, an axial scan was acquired at every 3 s over 60 s (i.e., 20 time points). Each time point acquired 28 contiguous transaxial slices with reconstructed voxels 0.16 x 0.16 x 1 mm3. Regions-of-interest in the outer 2/3 of the arterial wall and in the middle 2/3 of the lumen were drawn and their enhancements plotted versus time. Lumenal CT values peaked several seconds after injection and then returned towards baseline. Arterial wall CT values peaked concurrent to the lumen. The peak arterial wall enhancement in the left carotid arterial wall correlated with increased vasa vasorum density observed in micro-CT images of the isolated arteries.

  5. A high resolution laser ranging system based on time-correlated single-photon counting technology

    Science.gov (United States)

    Yang, Yixin; Wang, Huanqin; Huang, Zhe; Cao, Yangyang; Gui, Huaqiao

    2014-12-01

    Laser ranging has become an important method for both distance measurements and acquisition of threedimensional (3D) images. In this paper, a laser ranging system based on Time-Correlated Single-Photon Counting technology (TCSPC) is developed. A Geiger-mode avalanche photodiode (G-APD), which has the ability of detecting single-photon events, is used to capture the weak light scattered from the long-range target. In order to improve the ranging resolution of TCSPC based measurement system, a high repetition frequency of subnanosecond narrow pulse generator circuit based on the avalanche effect of RF-BJT is designed and applied as the light source. Moreover, some optimized optical light designs have been done to improve the system signal to noise rate (SNR), including using a special aspherical lens as projecting lens, adopting a telephoto camera lens with small view angle and short depth of field before detector. Experimental tests for evaluation of the laser raging system performance are described. As a means of echo signal analysis, three different algorithms have been introduced, in which the cross-correlation algorithm was demonstrated to be the most effective algorithm to determining the round trip time to a target, even based on histograms with a significant amount of background noise photons. It was found that centimeter ranging resolution can be achieved thanks to the use of Time-to-Digital Converter (TDC) with picosecond resolution and the Cross-Correlation algorithm. The proposed laser ranging system has advantages of high range resolution, short response time and simple structure, which was potential applications for 3D object recognition, computer vision, reverse engineering and virtual reality.

  6. Scalable time-correlated photon counting system with multiple independent input channels.

    Science.gov (United States)

    Wahl, Michael; Rahn, Hans-Jürgen; Röhlicke, Tino; Kell, Gerald; Nettels, Daniel; Hillger, Frank; Schuler, Ben; Erdmann, Rainer

    2008-12-01

    Time-correlated single photon counting continues to gain importance in a wide range of applications. Most prominently, it is used for time-resolved fluorescence measurements with sensitivity down to the single molecule level. While the primary goal of the method used to be the determination of fluorescence lifetimes upon optical excitation by short light pulses, recent modifications and refinements of instrumentation and methodology allow for the recovery of much more information from the detected photons, and enable entirely new applications. This is achieved most successfully by continuously recording individually detected photons with their arrival time and detection channel information (time tagging), thus avoiding premature data reduction and concomitant loss of information. An important property of the instrumentation used is the number of detection channels and the way they interrelate. Here we present a new instrument architecture that allows scalability in terms of the number of input channels while all channels are synchronized to picoseconds of relative timing and yet operate independent of each other. This is achieved by means of a modular design with independent crystal-locked time digitizers and a central processing unit for sorting and processing of the timing data. The modules communicate through high speed serial links supporting the full throughput rate of the time digitizers. Event processing is implemented in programmable logic, permitting classical histogramming, as well as time tagging of individual photons and their temporally ordered streaming to the host computer. Based on the time-ordered event data, any algorithms and methods for the analysis of fluorescence dynamics can be implemented not only in postprocessing but also in real time. Results from recently emerging single molecule applications are presented to demonstrate the capabilities of the instrument.

  7. Detective quantum efficiency of photon-counting x-ray detectors.

    Science.gov (United States)

    Tanguay, Jesse; Yun, Seungman; Kim, Ho Kyung; Cunningham, Ian A

    2015-01-01

    Single-photon-counting (SPC) x-ray imaging has the potential to improve image quality and enable novel energy-dependent imaging methods. Similar to conventional detectors, optimizing image SPC quality will require systems that produce the highest possible detective quantum efficiency (DQE). This paper builds on the cascaded-systems analysis (CSA) framework to develop a comprehensive description of the DQE of SPC detectors that implement adaptive binning. The DQE of SPC systems can be described using the CSA approach by propagating the probability density function (PDF) of the number of image-forming quanta through simple quantum processes. New relationships are developed to describe PDF transfer through serial and parallel cascades to accommodate scatter reabsorption. Results are applied to hypothetical silicon and selenium-based flat-panel SPC detectors including the effects of reabsorption of characteristic/scatter photons from photoelectric and Compton interactions, stochastic conversion of x-ray energy to secondary quanta, depth-dependent charge collection, and electronic noise. Results are compared with a Monte Carlo study. Depth-dependent collection efficiency can result in substantial broadening of photopeaks that in turn may result in reduced DQE at lower x-ray energies (20-45 keV). Double-counting interaction events caused by reabsorption of characteristic/scatter photons may result in falsely inflated image signal-to-noise ratio and potential overestimation of the DQE. The CSA approach is extended to describe signal and noise propagation through photoelectric and Compton interactions in SPC detectors, including the effects of escape and reabsorption of emission/scatter photons. High-performance SPC systems can be achieved but only for certain combinations of secondary conversion gain, depth-dependent collection efficiency, electronic noise, and reabsorption characteristics.

  8. Detective quantum efficiency of photon-counting x-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Tanguay, Jesse, E-mail: jessetan@mail.ubc.ca [Robarts Research Institute, Western University, London, Ontario N6A 5C1, Canadaand Department of Medical Biophysics, Western University, London, Ontario, N6A 3K7 (Canada); Yun, Seungman [Biomedical Engineering Program, Western University, London, Ontario, N6A 3K7, Canadaand School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-73 (Korea, Republic of); Kim, Ho Kyung [School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-73 (Korea, Republic of); Cunningham, Ian A. [Robarts Research Institute, Western University, London, Ontario N6A 5C1 (Canada); Department of Medical Biophysics, Western University, London, Ontario, N6A 3K7 (Canada); Biomedical Engineering Program, Western University, London, Ontario, N6A 3K7 (Canada)

    2015-01-15

    Purpose: Single-photon-counting (SPC) x-ray imaging has the potential to improve image quality and enable novel energy-dependent imaging methods. Similar to conventional detectors, optimizing image SPC quality will require systems that produce the highest possible detective quantum efficiency (DQE). This paper builds on the cascaded-systems analysis (CSA) framework to develop a comprehensive description of the DQE of SPC detectors that implement adaptive binning. Methods: The DQE of SPC systems can be described using the CSA approach by propagating the probability density function (PDF) of the number of image-forming quanta through simple quantum processes. New relationships are developed to describe PDF transfer through serial and parallel cascades to accommodate scatter reabsorption. Results are applied to hypothetical silicon and selenium-based flat-panel SPC detectors including the effects of reabsorption of characteristic/scatter photons from photoelectric and Compton interactions, stochastic conversion of x-ray energy to secondary quanta, depth-dependent charge collection, and electronic noise. Results are compared with a Monte Carlo study. Results: Depth-dependent collection efficiency can result in substantial broadening of photopeaks that in turn may result in reduced DQE at lower x-ray energies (20–45 keV). Double-counting interaction events caused by reabsorption of characteristic/scatter photons may result in falsely inflated image signal-to-noise ratio and potential overestimation of the DQE. Conclusions: The CSA approach is extended to describe signal and noise propagation through photoelectric and Compton interactions in SPC detectors, including the effects of escape and reabsorption of emission/scatter photons. High-performance SPC systems can be achieved but only for certain combinations of secondary conversion gain, depth-dependent collection efficiency, electronic noise, and reabsorption characteristics.

  9. Photon counting CT of the liver with dual-contrast enhancement

    Science.gov (United States)

    Muenzel, Daniela; Proksa, Roland; Daerr, Heiner; Fingerle, Alexander A.; Pfeiffer, Franz; Rummeny, Ernst J.; Noël, Peter B.

    2016-03-01

    The diagnostic quality of photon counting computed tomography (PCCT) is one the unexplored areas in medical imaging; at the same time, it seems to offer the opportunity as a fast and highly sensitive diagnostic tool. Today, conventional computed tomography (CT) is the standard imaging technique for diagnostic evaluation of the parenchyma of the liver. However, considerations on radiation dose are still an important factor in CT liver imaging, especially with regard to multi-phase contrast enhanced CT. In this work we report on a feasibility study for multi-contrast PCCT for simultaneous liver imaging at different contrast phases. PCCT images of the liver were simulated for a contrast-enhanced examination performed with two different contrast agents (CA), iodine (CA 1) and gadolinium (CA 2). PCCT image acquisition was performed at the time point with portal venous contrast distribution of CA 1 and arterial contrast phase for CA 2. Therefore, a contrast injection protocol was planned with sequential injection of CA 1 and CA 2 to provide a time dependent difference in contrast distribution of both CAs in the vessels and parenchyma of the liver. Native, arterial, and portal venous contrast enhanced images have been calculated based on the spectral separation of PCCT. In simulated PCCT images, we were able to differentiate between the tissue enhancement of CA 1 and CA 2. The distribution of both CA within the parenchyma of the liver was illustrated with perfusion maps for CA 1 and CA 2. In addition, virtual noncontrast enhanced image were calculated. In conclusion, multi-phase PCCT imaging of the liver based on a single scan is a novel approach for spectral PCCT imaging, offering detailed contrast information in a single scan volume and a significant reduction of radiation dose.

  10. Ultra-compact 32-channel system for time-correlated single-photon counting measurements

    Science.gov (United States)

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

    2013-05-01

    Modern Time-Correlated Single-Photon Counting applications require to detect spectral and temporal fluorescence data simultaneously and from different areas of the analyzed sample. These rising quests have led the development of multichannel systems able to perform high count rate and high performance analysis. In this work we describe a new 32-channel TCSPC system designed to be used in modern setups. The presented module consists of four independent 8-channel TCSPC boards, each of them including two 4-channel Time-Amplitude Converter arrays. These TAC arrays are built-in 0.35 μm Si-Ge BiCMOS technology and are characterized by low crosstalk, high resolution, high conversion rate and variable full-scale range. The 8-channel TCSPC board implements an 8-channel ADC to sample the TAC outputs, an FPGA to record and organize the measurement results and a USB 2.0 interface to enable real-time data transmission to and from an external PC. Experimental results demonstrate that the acquisition system ensures high performance TCSPC measurements, in particular: high conversion rate (5 MHz), good time resolution (down to 30 psFWHM with the full scale range set to 11 ns) and low differential non-linearity (rms value lower than 0.15% of the time bin width). We design the module to be very compact and, thanks to the reduced dimensions of the 8-channel TCSPC board (95×40 mm), the whole system can be enclosed in a small aluminum case (160×125×30 mm).

  11. The Solid State X-ray Image Intensifier (SSXII) in Single Photon Counting (SPC) mode.

    Science.gov (United States)

    Kuhls-Gilcrist, Andrew; Jain, Amit; Bednarek, Daniel R; Rudin, Stephen

    2010-03-22

    The new Solid State X-Ray Image Intensifier (SSXII) has the unique ability to operate in single photon counting (SPC) mode, with improved resolution, as well as in traditional energy integrating (EI) mode. The SSXII utilizes an electron-multiplying CCD (EMCCD), with an effective pixel size of 32μm, which enables variable signal amplification (up to a factor of 2000) prior to digital readout, providing very high-sensitivity capabilities. The presampled MTF was measured in both imaging modes using the standard angulated-slit method. A measured detector entrance exposure of 24μR per frame was used to provide approximately 0.8 interaction events per pixel in the 10μm-wide slit area. For demonstration purposes, a simple thresholding technique was used to localize events in SPC mode and a number of such frames were summed to provide an image with the same total exposure used for acquiring the EI image. The MTF for SPC mode, using a threshold level of 15% of the maximum 12-bit signal and 95% of the expected events, and for EI mode (in parentheses) was 0.67 (0.20), 0.37 (0.07), 0.20 (0.03), and 0.11 (0.01) at 2.5, 5, 7.5, and 10 cycles/mm, respectively. Increasing the threshold level resulted in a corresponding increase in the measured SPC MTF and a lower number of detected events, indicating a tradeoff between resolution and count efficiency is required. The SSXII in SPC mode was shown to provide substantial improvements in resolution relative to traditional EI mode, which should benefit applications that have demanding spatial resolution requirements, such as mammography.

  12. Dual energy CT kidney stone differentiation in photon counting computed tomography

    Science.gov (United States)

    Gutjahr, R.; Polster, C.; Henning, A.; Kappler, S.; Leng, S.; McCollough, C. H.; Sedlmair, M. U.; Schmidt, B.; Krauss, B.; Flohr, T. G.

    2017-03-01

    This study evaluates the capabilities of a whole-body photon counting CT system to differentiate between four common kidney stone materials, namely uric acid (UA), calcium oxalate monohydrate (COM), cystine (CYS), and apatite (APA) ex vivo. Two different x-ray spectra (120 kV and 140 kV) were applied and two acquisition modes were investigated. The macro-mode generates two energy threshold based image-volumes and two energy bin based image-volumes. In the chesspattern-mode four energy thresholds are applied. A virtual low energy image, as well as a virtual high energy image are derived from initial threshold-based images, while considering their statistically correlated nature. The energy bin based images of the macro-mode, as well as the virtual low and high energy image of the chesspattern-mode serve as input for our dual energy evaluation. The dual energy ratio of the individually segmented kidney stones were utilized to quantify the discriminability of the different materials. The dual energy ratios of the two acquisition modes showed high correlation for both applied spectra. Wilcoxon-rank sum tests and the evaluation of the area under the receiver operating characteristics curves suggest that the UA kidney stones are best differentiable from all other materials (AUC = 1.0), followed by CYS (AUC ≍ 0.9 compared against COM and APA). COM and APA, however, are hardly distinguishable (AUC between 0.63 and 0.76). The results hold true for the measurements of both spectra and both acquisition modes.

  13. 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.

  14. SU-E-I-77: A Noise Reduction Technique for Energy-Resolved Photon-Counting Detectors

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-06-01

    Purpose: Finding the optimal energy threshold setting for an energy-resolved photon-counting detector has an important impact on the maximization of contrast-to-noise-ratio (CNR). We introduce a noise reduction method to enhance CNR by reducing the noise in each energy bin without altering the average gray levels in the projection and image domains. Methods: We simulated a four bin energy-resolved photon-counting detector based on Si with a 10 mm depth of interaction. TASMIP algorithm was used to simulate a spectrum of 65 kVp with 2.7 mm Al filter. A 13 mm PMMA phantom with hydroxyapatite and iodine at different concentrations (100, 200 and 300 mg/ml for HA, and 2, 4, and 8 mg/ml for Iodine) was used. Projection-based and Image-based energy weighting methods were used to generate weighted images. A reference low noise image was used for noise reduction purposes. A Gaussian-like weighting function which computes the similarity between pixels of interest was calculated from the reference image and implemented on a pixel by pixel basis for the noisy images. Results: CNR improvement compared to different methods (Charge-Integrated, Photon-Counting and Energy-Weighting) and after noise reduction was highly task-dependent. The CNR improvement with respect to the Charge-Integrated CNR for hydroxyapatite and iodine were 1.8 and 1.5, respectively. In each of the energy bins, the noise was reduced by approximately factor of two without altering their respective average gray levels. Conclusion: The proposed noise reduction technique for energy-resolved photon-counting detectors can significantly reduce image noise. This technique can be used as a compliment to the current energy-weighting methods in CNR optimization.

  15. Visualization of the Light-Emitting Region from Cavitation in Circular Orifice Flows by the Photon Counting Method

    OpenAIRE

    田部井, 勝稲; 白井, 紘行; 高草木, 文雄

    1993-01-01

    Emission experiments on cavitation bubbles in water were performed with circular orifice flows. The region emitting faint light due to the bubbles was visualized with the combined method of photon counting and computerized tomography. Emission data obtained from outer-side observation were inverted into internal intensity distributions by means of the modified Abel transformation in which the light-quenching effect by cavitation bubbles was taken into account. It was observed that, under the ...

  16. Energy Calibration of a CdTe Photon Counting Spectral Detector with Consideration of its Non-Convergent Behavior

    Directory of Open Access Journals (Sweden)

    Jeong Seok Lee

    2016-04-01

    Full Text Available Fast and accurate energy calibration of photon counting spectral detectors (PCSDs is essential for their biomedical applications to identify and characterize bio-components or contrast agents in tissues. Using the x-ray tube voltage as a reference for energy calibration is known to be an efficient method, but there has been no consideration in the energy calibration of non-convergent behavior of PCSDs. We observed that a single pixel mode (SPM CdTe PCSD based on Medipix-2 shows some non-convergent behaviors in turning off the detector elements when a high enough threshold is applied to the comparator that produces a binary photon count pulse. More specifically, the detector elements are supposed to stop producing photon count pulses once the threshold reaches a point of the highest photon energy determined by the tube voltage. However, as the x-ray exposure time increases, the threshold giving 50% of off pixels also increases without converging to a point. We established a method to take account of the non-convergent behavior in the energy calibration. With the threshold-to-photon energy mapping function established by the proposed method, we could better identify iodine component in a phantom consisting of iodine and other components.

  17. A hybrid Monte Carlo model for the energy response functions of X-ray photon counting detectors

    Science.gov (United States)

    Wu, Dufan; Xu, Xiaofei; Zhang, Li; Wang, Sen

    2016-09-01

    In photon counting computed tomography (CT), it is vital to know the energy response functions of the detector for noise estimation and system optimization. Empirical methods lack flexibility and Monte Carlo simulations require too much knowledge of the detector. In this paper, we proposed a hybrid Monte Carlo model for the energy response functions of photon counting detectors in X-ray medical applications. GEANT4 was used to model the energy deposition of X-rays in the detector. Then numerical models were used to describe the process of charge sharing, anti-charge sharing and spectral broadening, which were too complicated to be included in the Monte Carlo model. Several free parameters were introduced in the numerical models, and they could be calibrated from experimental measurements such as X-ray fluorescence from metal elements. The method was used to model the energy response function of an XCounter Flite X1 photon counting detector. The parameters of the model were calibrated with fluorescence measurements. The model was further tested against measured spectrums of a VJ X-ray source to validate its feasibility and accuracy.

  18. A hybrid Monte Carlo model for the energy response functions of X-ray photon counting detectors

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Dufan; Xu, Xiaofei [Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Zhang, Li, E-mail: zli@mail.tsinghua.edu.cn [Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Wang, Sen [Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2016-09-11

    In photon counting computed tomography (CT), it is vital to know the energy response functions of the detector for noise estimation and system optimization. Empirical methods lack flexibility and Monte Carlo simulations require too much knowledge of the detector. In this paper, we proposed a hybrid Monte Carlo model for the energy response functions of photon counting detectors in X-ray medical applications. GEANT4 was used to model the energy deposition of X-rays in the detector. Then numerical models were used to describe the process of charge sharing, anti-charge sharing and spectral broadening, which were too complicated to be included in the Monte Carlo model. Several free parameters were introduced in the numerical models, and they could be calibrated from experimental measurements such as X-ray fluorescence from metal elements. The method was used to model the energy response function of an XCounter Flite X1 photon counting detector. The parameters of the model were calibrated with fluorescence measurements. The model was further tested against measured spectrums of a VJ X-ray source to validate its feasibility and accuracy.

  19. Evaluation of a photon-counting hybrid pixel detector array with a synchrotron X-ray source

    Science.gov (United States)

    Ponchut, C.; Visschers, J. L.; Fornaini, A.; Graafsma, H.; Maiorino, M.; Mettivier, G.; Calvet, D.

    2002-05-01

    A photon-counting hybrid pixel detector (Medipix-1) has been characterized using a synchrotron X-ray source. The detector consists of a readout ASIC with 64×64 independent photon-counting cells of 170×170 μm 2 pitch, bump-bonded to a 300 μm thick silicon sensor, read out by a PCIbus-based electronics, and a graphical user interface (GUI) software. The intensity and the energy tunability of the X-ray source allow characterization of the detector in the time, space, and energy domains. The system can be read out on external trigger at a frame rate of 100 Hz with 3 ms exposure time per frame. The detector response is tested up to more than 7×10 5 detected events/pixel/s. The point-spread response shows beam reveals no loss in sensitivity between adjacent pixels as could result from charge sharing in the silicon sensor. Photons down to 6 keV can be detected after equalization of the thresholds of individual pixels. The obtained results demonstrate the advantages of photon-counting hybrid pixel detectors and particularly of the Medipix-1 chip for a wide range of X-ray imaging applications, including those using synchrotron X-ray beams.

  20. Development and analysis of a photon-counting three-dimensional imaging laser detection and ranging (LADAR) system.

    Science.gov (United States)

    Oh, Min Seok; Kong, Hong Jin; Kim, Tae Hoon; Jo, Sung Eun; Kim, Byung Wook; Park, Dong Jo

    2011-05-01

    In this paper, a photon-counting three-dimensional imaging laser detection and ranging (LADAR) system that uses a Geiger-mode avalanche photodiode (GAPD) of relatively short dead time (45 ns) is described. A passively Q-switched microchip laser is used as a laser source and a compact peripheral component interconnect system, which includes a time-to-digital converter (TDC), is set up for fast signal processing. The combination of a GAPD with short dead time and a TDC with a multistop function enables the system to operate in a single-hit or a multihit mode during the acquisition of time-of-flight data. The software for the three-dimensional visualization and an algorithm for the removal of noise are developed. For the photon-counting LADAR system, we establish a theoretical model of target-detection and false-alarm probabilities in both the single-hit and multihit modes with a Poisson statistic; this model provides the prediction of the performance of the system and a technique for the acquisition of a noise image with a GAPD. Both the noise image and the three-dimensional image of a scene acquired by the photon-counting LADAR system during the day are presented.

  1. Development of CdTe pixel detectors combined with an aluminum Schottky diode sensor and photon-counting ASICs

    Science.gov (United States)

    Toyokawa, H.; Saji, C.; Kawase, M.; Wu, S.; Furukawa, Y.; Kajiwara, K.; Sato, M.; Hirono, T.; Shiro, A.; Shobu, T.; Suenaga, A.; Ikeda, H.

    2017-01-01

    We have been developing CdTe pixel detectors combined with a Schottky diode sensor and photon-counting ASICs. The hybrid pixel detector was designed with a pixel size of 200 μ m by 200 μm and an area of 19 mm by 20 mm or 38.2 mm by 40.2 mm. The photon-counting ASIC, SP8-04F10K, has a preamplifier, a shaper, 3-level window-type discriminators and a 24-bits counter in each pixel. The single-chip detector with 100 by 95 pixels successfully operated with a photon-counting mode selecting X-ray energy with the window comparator and stable operation was realized at 20 degrees C. We have performed a feasibility study for a white X-ray microbeam experiment. Laue diffraction patterns were measured during the scan of the irradiated position in a silicon steel sample. The grain boundaries were identified by using the differentials between adjacent images at each position.

  2. Direct Detection of sub-GeV Dark Matter with Scintillating Targets

    CERN Document Server

    Derenzo, Stephen; Massari, Andrea; Soto, Adrían; Yu, Tien-Tien

    2016-01-01

    We describe a novel search for MeV-to-GeV-mass dark matter, in which the dark matter scatters off electrons in a scintillating target. The excitation and subsequent de-excitation of the electron produces one or more photons, which could be detected with an array of cryogenic low-noise photodetectors, such as transition edge sensors (TES) or microwave kinetic inductance devices (MKID). Scintillators may have distinct advantages over other experiments searching for a low ionization signal from sub-GeV DM. First, the detection of one or a few photons may be technologically easier. Second, since no electric field is required to detect the photons, there may be far fewer dark counts mimicking a DM signal. We discuss various target choices, but focus on calculating the expected dark matter-electron scattering rates in three scintillating crystals, sodium iodide (NaI), cesium iodide (CsI), and gallium arsenide (GaAs). Among these, GaAs has the lowest band gap (1.52 eV) compared to NaI (5.9 eV) or CsI (6.4 eV), allow...

  3. Optical Design Considerations for Efficient Light Collection from Liquid Scintillation Counters

    Energy Technology Data Exchange (ETDEWEB)

    Bernacki, Bruce E.; Douglas, Matthew; Erchinger, Jennifer L.; Fuller, Erin S.; Keillor, Martin E.; Morley, Shannon M.; Mullen, Crystal A.; Orrell, John L.; Panisko, Mark E.; Warren, Glen A.; Wright, Michael E.

    2015-01-01

    Liquid scintillation counters measure charged particle-emitting radioactive isotopes and are used for environmental studies, nuclear chemistry, and life science. Alpha and beta emissions arising from the material under study interact with the scintillation cocktail to produce light. The prototypical liquid scintillation counter employs low-level photon-counting detectors to measure the arrival of the scintillation light produced as a result of the dissolved material under study interacting with the scintillation cocktail. For reliable operation the counting instrument must convey the scintillation light to the detectors efficiently and predictably. Current best practices employ the use of two or more detectors for coincidence processing to discriminate true scintillation events from background events due to instrumental effects such as photomultiplier tube dark rates, tube flashing, or other light emission not generated in the scintillation cocktail vial. In low background liquid scintillation counters additional attention is paid to shielding the scintillation cocktail from naturally occurring radioactive material (NORM) present in the laboratory and within the instruments construction materials. Low background design is generally at odds with optimal light collection. This study presents the evolution of a light collection design for liquid scintillation counting in a low background shield. The basic approach to achieve both good light collection and a low background measurement is described. The baseline signals arising from the scintillation vial are modeled and methods to efficiently collect scintillation light are presented as part of the development of a customized low-background, high sensitivity liquid scintillation counting system.

  4. 18k Channels single photon counting readout circuit for hybrid pixel detector

    Science.gov (United States)

    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.

  5. 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.

  6. Light pulses to photomultiplier tubes from extended scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Albergo, S. [Catania Univ. (Italy). Ist. di Fisica; Boemi, D. [CSFNeSM, I-95129 Catania (Italy); Caccia, Z. [Catania Univ. (Italy). Ist. di Fisica; Costa, S. [Catania Univ. (Italy). Ist. di Fisica; Insolia, A. [Catania Univ. (Italy). Ist. di Fisica; Panebianco, S. [Catania Univ. (Italy). Ist. di Fisica; Potenza, R. [Catania Univ. (Italy). Ist. di Fisica; Randazzo, N. [Catania Univ. (Italy). Ist. di Fisica; Reito, S. [Catania Univ. (Italy). Ist. di Fisica; Romanski, J. [The Svedberg Laboratory, University of Uppsala, S751-21 Uppsala (Sweden); Russo, G.V. [Catania Univ. (Italy). Ist. di Fisica; Tuve, C. [Catania Univ. (Italy). Ist. di Fisica

    1995-08-15

    Light pulses seen by photomultiplier tubes (PMTs) after propagation within long scintillator slats or rods, or large disc-shaped scintillators are investigated and compared with those from point-like scintillators. Results of experimental tests for the disc-shaped configuration, performed with the single photon counting technique, are presented and compared with numerical calculations. These calculations were performed describing the light pulse shape by means of a new, quite general analytical method based on the geometrical optics concepts of virtual light paths and images. The associated electric pulses produced by the PMTs coupled to the scintillators are then discussed with particular emphasis on their dependence on the distance between light source and photocathode. (orig.).

  7. Uniformity Studies of Scintillator Tiles directly coupled to SiPMs for Imaging Calorimetry

    CERN Document Server

    Simon, Frank

    2010-01-01

    We present a novel geometry of scintillator tiles developed for fiberless coupling to silicon photomultipliers (SiPMs) for applications in highly granular calorimeters. A high degree of uniformity of the tile response over the full active area was achieved by a drilled slit at the coupling position of the photon sensor with 2 mm, 4 mm and 5.5 mm in height, width and depth. Detailed measurements of the response to penetrating electrons were performed for tiles with a lateral size of 3 x 3 cm^2 and thicknesses of 5 mm and 3 mm.

  8. Single-photon counting for the 1300-1600-nm range by use of peltier-cooled and passively quenched InGaAs avalanche photodiodes.

    Science.gov (United States)

    Rarity, J G; Wall, T E; Ridley, K D; Owens, P C; Tapster, P R

    2000-12-20

    We evaluate the performance of various commercially available InGaAs/InP avalanche photodiodes for photon counting in the infrared at temperatures that can be reached by Peltier cooling. We find that dark count rates are high, and this can partially saturate devices before optimum performance is achieved. At low temperatures the dark count rate rises because of a strong contribution from correlated afterpulses. We discuss ways of suppressing these afterpulses for different photon-counting applications.

  9. An innovative method to reduce count loss from pulse pile-up in a photon-counting pixel for high flux X-ray applications

    Science.gov (United States)

    Lee, D.; Lim, K.; Park, K.; Lee, C.; Alexander, S.; Cho, G.

    2017-03-01

    In this study, an innovative fast X-ray photon-counting pixel for high X-ray flux applications is proposed. A computed tomography system typically uses X-ray fluxes up to 108 photons/mm2/sec at the detector and thus a fast read-out is required in order to process individual X-ray photons. Otherwise, pulse pile-up can occur at the output of the signal processing unit. These superimposed signals can distort the number of incident X-ray photons leading to count loss. To minimize such losses, a cross detection method was implemented in the photon-counting pixel. A maximum count rate under X-ray tube voltage of 90 kV was acquired which reflect electrical test results of the proposed photon counting pixel. A maximum count of 780 kcps was achieved with a conventional photon-counting pixel at the pulse processing time of 500 ns, which is the time for a pulse to return to the baseline from the initial rise. In contrast, the maximum count of about 8.1 Mcps was achieved with the proposed photon-counting pixel. From these results, it was clear that the maximum count rate was increased by approximately a factor 10 times by adopting the cross detection method. Therefore, it is an innovative method to reduce count loss from pulse pile-up in a photon-counting pixel while maintaining the pulse processing time.

  10. Contrast optimization in X-ray radiography with single photon counting imagers of Medipix type

    Science.gov (United States)

    Jandejsek, I.; Dammer, J.; Jakubek, J.; Vavrik, D.; Zemlicka, J.

    2012-12-01

    Systematical measurement and optimization of the image contrast in the terms of the signal to noise ratio (SNR) reached by two detector systems Medipix2 (Si sensor) and Flat Panel (Scintillator + CMOS) is the aim of this work. The measurement is carried out with micro-focus X-ray source and aluminum step phantom specimen of various thicknesses. The SNR is computed from measured image data for various combination of aluminum thicknesses and in dependence on tube voltage and acquisition time. On the basis of the results, the comparison of two detector systems is done and the illustrative SNR optimization process for a hypothetical and real samples is demonstrated.

  11. 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.

    2016-02-01

    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

  12. 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

  13. 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.

  14. 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 advantages over "frame driven" recording devices for some important applications. For example we have built open face and sealed tube cross delay line detectors used for biological fluorescence lifetime imaging, observation of flare stars, orbital satellites and space debris with the GALEX satellite, and time resolved imaging of the Crab 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

  15. Fast identification of substance by measuring two Raman peaks with dual strip silicon photomultipliers and gated photon counting technique.

    Science.gov (United States)

    Zhang, Guoqing; Hu, Xiaobo; Cheng, Yue; Zhang, Chunling; Liu, Lina; Yang, Ru; Liang, Kun; Han, Dejun

    2011-08-20

    In this report, we use carbon tetrachloride as an example to demonstrate that substance can be quickly identified through the measurement of the two Raman peaks simply by an integrated module of dual strip silicon photomultipliers operating at room temperature in conjunction with a gated photon counting technique. Both the peak positions and the relative intensity ratio of the two Raman peaks are used to identify the substance with a reduced false acceptance rate. A complete Raman spectrum of the substance can also be measured by using this method combined with a scanning monochromator. © 2011 Optical Society of America

  16. Study of the response and photon-counting resolution of silicon photomultipliers using a generic simulation framework

    CERN Document Server

    Eckert, P; Schultz-Coulon, H.C

    2012-01-01

    which enables detailed modelling of the SiPM response using basic SiPM parameters and geometry as an input. Depending on the specified SiPM properties which can be determined from basic characterisation measurements, the simulation generates the signal charge and pulse shape for arbitrary incident light pulse distributions. The simulation has been validated in the whole dynamic range for a Hamamatsu S10362-11-100C MPPC and was used to study the effect of different noise sources like optical cross-talk and after-pulsing on the response curve and the photon-counting resolution.

  17. Silicon Detector Arrays with Absolute Quantum Efficiency over 50% in the Far Ultraviolet for Single Photon Counting Applications

    CERN Document Server

    Nikzad, Shouleh; Greer, Frank; Jones, Todd; Jacquot, Blake; Monacos, Steve; Blacksberg, J; Hamden, Erika; Schiminovich, David; Martin, Chris; Morrissey, Patrick

    2011-01-01

    We have used Molecular Beam Epitaxy (MBE)-based delta doping technology to demonstrate near 100% internal quantum efficiency (QE) on silicon electron-multiplied Charge Coupled Devices (EMCCDs) for single photon counting detection applications. Furthermore, we have used precision techniques for depositing antireflection (AR) coatings by employing Atomic Layer Deposition (ALD) and demonstrated over 50% external QE in the far and near-ultraviolet in megapixel arrays. We have demonstrated that other device parameters such as dark current are unchanged after these processes. In this paper, we report on these results and briefly discuss the techniques and processes employed.

  18. Design of a control system for ultrafast x-ray camera working in a single photon counting mode

    Science.gov (United States)

    Zoladz, Miroslaw; Rauza, Jacek; Kasinski, Krzysztof; Maj, Piotr; Grybos, Pawel

    2015-09-01

    Prototype of Ultra-Fast X-Ray Camera Controller working in a single photon counting mode and based on ASIC has been presented in this paper. An ASIC architecture has been discussed with special attention to digital part. We present the Custom Soft Processor as an ASIC control sequences generator. The Processor allows for dynamic program downloading and generating control sequences with up to 80MHz clock rate (preliminary results). Assembler with a very simple syntax has been defined to speed up Processor programs development. Discriminators threshold dispersion correction has been performed to confirm proper Camera Controller operation.

  19. Large-aperture germanium detector package for picosecond photon counting in the 0.5-1.6-microm range.

    Science.gov (United States)

    Prochazka, I; Hamal, K; Greene, B; Kunimori, H

    1996-09-01

    We report the design, construction, and parameters of a detector package based on a germanium avalanche photodiode operated in the Geiger mode cooled to 77 K. The new design of the active quenching circuit, proper diode structure, and cryogenic cooling setup permitted us to increase the detector's active area to 0.1-mm diameter while maintaining an acceptable dark-count rate, timing resolution, and photon-counting sensitivity at 1.54 microm. The active-area size and the compact design of the detector package permitted its application in satellite laser ranging at 0.532- and 1.543-microm wavelengths, yielding subcentimeter ranging precision.

  20. Multi-Material Decomposition using Low-Current X-Ray and a Photon-Counting CZT Detector

    OpenAIRE

    Kim, Sangtaek; Hernandez, Andrew; Alhassen, Fares; Pivovaroff, Michael; Cho, Hyo-Min; Gould, Robert G.; Seo, Youngho

    2011-01-01

    We developed and evaluated an x-ray photon-counting imaging system using an energy-resolving cadmium zinc telluride (CZT) detector coupled with application specific integrated circuit (ASIC) readouts. This x-ray imaging system can be used to identify different materials inside the object. The CZT detector has a large active area (5×5 array of 25 CZT modules, each with 16×16 pixels, cover a total area of 200 mm × 200 mm), high stopping efficiency for x-ray photons (~ 100 % at 60 keV and 5 mm t...

  1. 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

  2. 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.)

  3. Photon counting imaging with an electron-bombarded CCD: Towards a parallel-processing photoelectronic time-to-amplitude converter

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, Liisa M.; Jiggins, Stephen; Sergent, Nicolas; Zanda, Gianmarco; Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom)

    2014-12-15

    We have used an electron-bombarded CCD for optical photon counting imaging. The photon event pulse height distribution was found to be linearly dependent on the gain voltage. We propose on this basis that a gain voltage sweep during exposure in an electron-bombarded sensor would allow photon arrival time determination with sub-frame exposure time resolution. This effectively uses an electron-bombarded sensor as a parallel-processing photoelectronic time-to-amplitude converter, or a two-dimensional photon counting streak camera. Several applications that require timing of photon arrival, including Fluorescence Lifetime Imaging Microscopy, may benefit from such an approach. A simulation of a voltage sweep performed with experimental data collected with different acceleration voltages validates the principle of this approach. Moreover, photon event centroiding was performed and a hybrid 50% Gaussian/Centre of Gravity + 50% Hyperbolic cosine centroiding algorithm was found to yield the lowest fixed pattern noise. Finally, the camera was mounted on a fluorescence microscope to image F-actin filaments stained with the fluorescent dye Alexa 488 in fixed cells.

  4. Grating-based interferometry and hybrid photon counting detectors: Towards a new era in X-ray medical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gkoumas, Spyridon, E-mail: spyridon.gkoumas@psi.ch [Swiss Light Source, Paul Scherrer Institut, Villigen 5232 (Switzerland); Wang, Zhentian; Abis, Matteo; Arboleda, Carolina [Swiss Light Source, Paul Scherrer Institut, Villigen 5232 (Switzerland); Institute for Biomedical Engineering,University and ETH Zurich, Zurich 8092 (Switzerland); Tudosie, George; Donath, Tilman; Brönnimann, Christian; Schulze-Briese, Clemens [Dectris Ltd., Neuenhoferstrasse 107, Baden 5400 (Switzerland); Stampanoni, Marco [Swiss Light Source, Paul Scherrer Institut, Villigen 5232 (Switzerland); Institute for Biomedical Engineering,University and ETH Zurich, Zurich 8092 (Switzerland)

    2016-02-11

    Progress in X-ray medical imaging and advances in detector developments have always been closely related. Similarly, a strong connection exists between innovations in synchrotron imaging and their implementation on table-top X-ray tube setups. The transfer of phase-based imaging to X-ray tubes can provide table-top setups with improved contrast between areas of low attenuation differences, by exploiting the unit decrement of the real part of the refractive index. Medical imaging is a potential application for such a system. Originally developed for synchrotron experiments, the novel generation of hybrid photon counting detectors is becoming increasingly popular due to their unique characteristics, such as small pixel size, negligible dark noise, fast counting and adjustable energy thresholds. Furthermore, novel room temperature semiconductor materials such as Cd(Zn)Te can provide higher quantum efficiency. In the first part of this article we review phase-contrast techniques and recent research towards medical applications. In the second part we present results and evaluate the potential of combining a table-top Talbot grating interferometry system with latest generation hybrid photon counting detectors.

  5. Evaluation of a photon-counting hybrid pixel detector array with a synchrotron X-ray source

    CERN Document Server

    Ponchut, C; Fornaini, A; Graafsma, H; Maiorino, M; Mettivier, G; Calvet, D

    2002-01-01

    A photon-counting hybrid pixel detector (Medipix-1) has been characterized using a synchrotron X-ray source. The detector consists of a readout ASIC with 64x64 independent photon-counting cells of 170x170 mu m sup 2 pitch, bump-bonded to a 300 mu m thick silicon sensor, read out by a PCIbus-based electronics, and a graphical user interface (GUI) software. The intensity and the energy tunability of the X-ray source allow characterization of the detector in the time, space, and energy domains. The system can be read out on external trigger at a frame rate of 100 Hz with 3 ms exposure time per frame. The detector response is tested up to more than 7x10 sup 5 detected events/pixel/s. The point-spread response shows <2% crosstalk between neighboring pixels. Fine scanning of the detector surface with a 10 mu m beam reveals no loss in sensitivity between adjacent pixels as could result from charge sharing in the silicon sensor. Photons down to 6 keV can be detected after equalization of the thresholds of individu...

  6. 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.

  7. Projection-based energy weighting on photon-counting X-ray images in digital subtraction mammography: a feasibility study

    Science.gov (United States)

    Choi, Sung-Hoon; Lee, Seung-Wan; Choi, Yu-Na; Lee, Young-Jin; Kim, Hee-Joung

    2014-03-01

    In digital subtraction mammography where subtracts the one image (with contrast medium) from the other (anatomical background) for observing the tumor structure, tumors which include more blood vessels than normal tissue could be distinguished through the enhancement of contrast-to-noise ratio (CNR). In order to improve CNR, we adopted projection-based energy weighting for iodine solutions with four different concentrations embedded in a breast phantom (50% adipose and 50% glandular tissues). In this study, a Monte Carlo simulation was used to simulate a 40 mm thickness breast phantom, which has 15 and 30 mg/cm3 iodine solutions with two different thicknesses, and an energy resolving photon-counting system. The input energy spectrum was simulated in a range of 20 to 45 keV in order to reject electronic noise and include 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 conventional integrating images. Consequently, the CNR of images from the digital subtraction mammography could be improved by the projection-based energy weighting with photon-counting detectors.

  8. 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.

  9. Digital filter based on the Fisher linear discriminant to reduce dead-time paralysis in photon counting

    Science.gov (United States)

    Sullivan, Shane Z.; Schmitt, Paul D.; DeWalt, Emma L.; Muir, Ryan D.; Simpson, Garth J.

    2013-03-01

    Photon counting represents the Poisson limit in signal to noise, but can often be complicated in imaging applications by detector paralysis, arising from the finite rise / fall time of the detector upon photon absorption. We present here an approach for reducing dead-time by generating a deconvolution digital filter based on optimizing the Fisher linear discriminant. In brief, two classes are defined, one in which a photon event is initiated at the origin of the digital filter, and one in the photon event is non-coincident with the filter origin. Linear discriminant analysis (LDA) is then performed to optimize the digital filter that best resolves the coincident and non-coincident training set data.1 Once trained, implementation of the filter can be performed quickly, significantly reducing dead-time issues and measurement bias in photon counting applications. Experimental demonstration of the LDA-filter approach was performed in fluorescence microscopy measurements using a highly convolved impulse response with considerable ringing. Analysis of the counts supports the capabilities of the filter in recovering deconvolved impulse responses under the conditions considered in the study. Potential additional applications and possible limitations are also considered.

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

    Science.gov (United States)

    Acciavatti, Raymond J; Maidment, Andrew D A

    2010-12-01

    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. 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. 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) > or = NPS(EI) and hence DQE(PC) function given as zero or unity everywhere. In analyzing the model detector with Gaussian blurring

  11. Semiconductor quantum dot scintillation under gamma-ray irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Letant, S E; Wang, T

    2006-08-23

    We recently demonstrated the ability of semiconductor quantum dots to convert alpha radiation into visible photons. In this letter, we report on the scintillation of quantum dots under gamma-ray irradiation, and compare the energy resolution of the 59 keV line of Americium 241 obtained with our quantum dot-glass nanocomposite material to that of a standard sodium iodide scintillator. A factor 2 improvement is demonstrated experimentally and interpreted theoretically using a combination of energy-loss and photon transport models. These results demonstrate the potential of quantum dots for room-temperature gamma-ray detection, which has applications in medical imaging, environmental monitoring, as well as security and defense. Present technology in gamma radiation detection suffers from flexibility and scalability issues. For example, bulk Germanium provides fine energy resolution (0.2% energy resolution at 1.33 MeV) but requires operation at liquid nitrogen temperature. On the other hand, Cadmium-Zinc-Telluride is a good room temperature detector ( 1% at 662 keV) but the size of the crystals that can be grown is limited to a few centimeters in each direction. Finally, the most commonly used scintillator, Sodium Iodide (NaI), can be grown as large crystals but suffers from a lack of energy resolution (7% energy resolution at 662 keV). Recent advancements in nanotechnology6-10 have provided the possibility of controlling materials synthesis at the molecular level. Both morphology and chemical composition can now be manipulated, leading to radically new material properties due to a combination of quantum confinement and surface to volume ratio effects. One of the main consequences of reducing the size of semiconductors down to nanometer dimensions is to increase the energy band gap, leading to visible luminescence, which suggests that these materials could be used as scintillators. The visible band gap of quantum dots would also ensure both efficient photon counting

  12. The effect of photon energy weighting on X-ray imaging based on a photon counting detector

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yu-Na; Lee, Seung-Wan; Cho, Hyo-Min; Ryu, Hyun-Ju; Lee, Young-Jin; Kim, Hee-Joung [Yonsei University, Wonju (Korea, Republic of)

    2011-11-15

    Development of photon counting detectors with the ability of energy discrimination would provide additional information. These detectors could improve the contrast-to-noise ratio (CNR) by using photon energy weighting with energy-dependent weighting factors. The purpose of this study was to evaluate the effect of photon energy weighting using GEANT4 Application for Tomographic Emission (GATE) version 6.0. The photon energy weighting depends on the X-ray attenuation coefficient of contrast elements and background materials. In this study, we simulated a photon counting X-ray imaging system. We designed a cadmium telluride (CdTe) photon counting detector (model PID-350, AJAT, Finland), the micro focus X-ray source (model L8601-01, Hamamatsu, Japan) and two phantoms with GATE. In the first case, we were concerned with calcifications in breast tissue or soft tissue. We defined a cubic phantom made of poly (methyl methacrylate) (PMMA) material with a thickness of 40 mm including four CaCO{sub 3} contrast elements with different thickness of 1.0, 3.0, 5.0, and 7.0 mm. In the second case, we designed a second phantom for contrast enhanced digital mammography (CEDM). We defined two cylindrical phantoms made of PMMA with thicknesses of 30 and 40 mm, including four iodine contrast elements with different thicknesses of 0.3, 0.5, 1.0, and 1.5 mm. The effect of photon energy weighting was investigated in terms of the CNR. In all cases, photon energy weighting improve the CNR. The CNR improvements for CaCO{sub 3} with thicknesses of 1.0, 3.0, 5.0, and 7.0 mm were 1.41, 1.32, 1.43, and 1.56, respectively. For the second phantom with a thickness of 30 mm, the CNR improvements of iodine contrast elements with thicknesses of 1.0, 3.0, 5.0, and 7.0 mm were 1.01, 1.03, 1.09, and 1.13, respectively, and for the second phantom with a thicknesses of 40 mm, the CNR improvements of iodine contrast elements with thickness of 1.0, 3.0, 5.0, and 7.0 mm were 1.05, 1.07, 1.16, and 1

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

    Science.gov (United States)

    Gimenez, E. N.; Astromskas, V.; Horswell, I.; Omar, D.; Spiers, J.; Tartoni, N.

    2016-07-01

    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- 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.

  14. Nanoscale optical thermometry using a time-correlated single-photon counting in an illumination-collection mode

    Science.gov (United States)

    Seto, Daichi; Nikka, Ren; Nishio, Shogo; Taguchi, Yoshihiro; Saiki, Toshiharu; Nagasaka, Yuji

    2017-01-01

    A nanoscale thermometry method called fluorescence near-field optics thermal nanoscopy (Fluor-NOTN) has been developed using near-field fluorescence imaging. This method can detect local temperature distributions with a nanoscale spatial resolution by measuring the fluorescence lifetimes of Cd/Se quantum dots (QDs) as a temperature probe. To increase the sensitivity of Fluor-NOTN, time-correlated single-photon counting (TCSPC) was introduced with a triple-tapered fusion-spliced near-field (TFN) optical fiber probe. This highly sensitive technique for measuring the fluorescence lifetime of QDs enabled the detection of low-level light signals with a picosecond time resolution at high-precision in an illumination-collection mode for Fluor-NOTN. The feasibility of this proposed method was experimentally verified by measuring the temperature dependence of the fluorescence lifetimes of the QDs by Fluor-NOTN using TCSPC with a TFN optical fiber probe with an aperture of 70 nm.

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

    CERN Document Server

    Mallick, M B; Ravindranath, S V G

    2002-01-01

    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 chi R sup 2 , weighted residuals and autocorrelation function. Performance is compared with two commercial software packages and found to be satisfactory.

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

    Science.gov (United States)

    Wei, Wei; Zhang, Jie; Ning, Zhe; Lu, Yunpeng; Fan, Lei; Li, Huaishen; Jiang, Xiaoshan; Lan, Allan K.; Ouyang, Qun; Wang, Zheng; Zhu, Kejun; Chen, Yuanbo; Liu, Peng

    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- rms after bump bonding and a threshold dispersion of 55 e- rms after calibration.

  17. High-speed single photon counting read out electronics for a digital detection system for clinical synchrotron radiation mammography

    Science.gov (United States)

    Bergamaschi, A.; Arfelli, F.; Dreossi, D.; Longo, R.; Olivo, A.; Pani, S.; Rigon, L.; Vallazza, E.; Venanzi, C.; Castelli, E.

    2004-02-01

    The SYRMEP beam line is currently in the upgrading phase for mammographic examinations on patients at Elettra in Trieste. At the same time, a digital detection system, suitable for in -vivo breast imaging, is under development; it consists of a silicon laminar detector array operating in single photon counting mode. The duration of a clinical examination should not exceed a few seconds. Fast read out electronics is therefore necessary with the aim of avoiding losses in image contrast in presence of high counting rates. A custom ASIC working with 100% efficiency for rates up to 100 kHz per pixel has been designed and tested, and other solutions based on commercially available ASICs are currently under test. Several detector prototypes have been assembled, and images of mammographic test objects have been acquired. Image quality, efficiency and contrast losses have been evaluated in all cases as a function of the counting rate.

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

    Science.gov (United States)

    Hirvonen, Liisa M.; Becker, Wolfgang; Milnes, James; Conneely, Thomas; Smietana, Stefan; Le Marois, Alix; Jagutzki, Ottmar; Suhling, Klaus

    2016-08-01

    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.

  19. 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.

  20. 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.

  1. Spectral performance of a whole-body research photon counting detector CT: quantitative accuracy in derived image sets

    Science.gov (United States)

    Leng, Shuai; Zhou, Wei; Yu, Zhicong; Halaweish, Ahmed; Krauss, Bernhard; Schmidt, Bernhard; Yu, Lifeng; Kappler, Steffen; McCollough, Cynthia

    2017-09-01

    Photon-counting computed tomography (PCCT) uses a photon counting detector to count individual photons and allocate them to specific energy bins by comparing photon energy to preset thresholds. This enables simultaneous multi-energy CT with a single source and detector. Phantom studies were performed to assess the spectral performance of a research PCCT scanner by assessing the accuracy of derived images sets. Specifically, we assessed the accuracy of iodine quantification in iodine map images and of CT number accuracy in virtual monoenergetic images (VMI). Vials containing iodine with five known concentrations were scanned on the PCCT scanner after being placed in phantoms representing the attenuation of different size patients. For comparison, the same vials and phantoms were also scanned on 2nd and 3rd generation dual-source, dual-energy scanners. After material decomposition, iodine maps were generated, from which iodine concentration was measured for each vial and phantom size and compared with the known concentration. Additionally, VMIs were generated and CT number accuracy was compared to the reference standard, which was calculated based on known iodine concentration and attenuation coefficients at each keV obtained from the U.S. National Institute of Standards and Technology (NIST). Results showed accurate iodine quantification (root mean square error of 0.5 mgI/cc) and accurate CT number of VMIs (percentage error of 8.9%) using the PCCT scanner. The overall performance of the PCCT scanner, in terms of iodine quantification and VMI CT number accuracy, was comparable to that of EID-based dual-source, dual-energy scanners.

  2. Discrimination between normal breast tissue and tumor tissue using CdTe series detector developed for photon-counting mammography

    Science.gov (United States)

    Okamoto, Chizuru; Ihori, Akiko; Yamakawa, Tsutomu; Yamamoto, Shuichiro; Okada, Masahiro; Kato, Misa; Nakajima, Ai; Kodera, Yoshie

    2016-03-01

    We propose a new mammography system using a cadmium telluride (CdTe) series photon-counting detector, having high absorption efficiency over a wide energy range. In a previous study, we showed that the use of high X-ray energy in digital mammography is useful from the viewpoint of exposure dose and image quality. In addition, the CdTe series detector can acquire X-ray spectrum information following transmission through a subject. This study focused on the tissue composition identified using spectral information obtained by a new photon-counting detector. Normal breast tissue consists entirely of adipose and glandular tissues. However, it is very difficult to find tumor tissue in the region of glandular tissue via a conventional mammogram, especially in dense breast because the attenuation coefficients of glandular tissue and tumor tissue are very close. As a fundamental examination, we considered a simulation phantom and showed the difference between normal breast tissue and tumor tissue of various thicknesses in a three-dimensional (3D) scatter plot. We were able to discriminate between both types of tissues. In addition, there was a tendency for the distribution to depend on the thickness of the tumor tissue. Thinner tumor tissues were shown to be closer in appearance to normal breast tissue. This study also demonstrated that the difference between these tissues could be made obvious by using a CdTe series detector. We believe that this differentiation is important, and therefore, expect this technology to be applied to new tumor detection systems in the future.

  3. Estimation of mammary gland composition using CdTe series detector developed for photon-counting mammography

    Science.gov (United States)

    Ihori, Akiko; Okamoto, Chizuru; Yamakawa, Tsutomu; Yamamoto, Shuichiro; Okada, Masahiro; Nakajima, Ai; Kato, Misa; Kodera, Yoshie

    2016-03-01

    Energy resolved photon-counting mammography is a new technology, which counts the number of photons that passes through an object, and presents it as a pixel value in an image of the object. Silicon semiconductor detectors are currently used in commercial mammography. However, the disadvantage of silicon is the low absorption efficiency for high X-ray energies. A cadmium telluride (CdTe) series detector has a high absorption efficiency over a wide energy range. In this study, we proposed a method to estimate the composition of the mammary gland using a CdTe series detector as a photon-counting detector. The fact that the detection rate of breast cancer in mammography is affected by mammary gland composition is now widely accepted. Assessment of composition of the mammary gland has important implications. An important advantage of our proposed technique is its ability to discriminate photons using three energy bins. We designed the CdTe series detector system using the MATLAB simulation software. The phantom contains nine regions with the ratio of glandular tissue and adipose varying in increments of 10%. The attenuation coefficient for each bin's energy was calculated from the number of input and output photons possessed by each. The evaluation results obtained by plotting the attenuation coefficient μ in a three-dimensional (3D) scatter plot show that the plots had a regular composition order congruent with that of the mammary gland. Consequently, we believe that our proposed method can be used to estimate the composition of the mammary gland.

  4. Measurements of the wavelength dependence and other properties of stellar scintillation at Mauna Kea, Hawaii.

    Science.gov (United States)

    Dainty, J C; Levine, B M; Brames, B J; O'Donnell, K A

    1982-04-01

    The variance of intensity of stellar scintillation has been measured as a function of wavelength using photon counting and on-line digital analysis techniques. The experimental data are consistent with that predicted by the theory of Tatarski. Measurements of the temporal correlation function of intensity and the higher moments of the probability density function of scintillation are also described. Time scales in the 1.7-10-msec range were observed, and the observed higher moments were consistently lower than those predicted by a log normal distribution. All the measurements were made at Mauna Kea Observatory, Hawaii.

  5. 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 measurement of Mn-54 and Zn-65 by liquid scintillation coincidence counting results in low detection efficiencies. The activity obtained from the extrapolation of efficiency data can therefore become problematic if curvature is present...

  6. 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.

  7. On the analogy between pulse-pile-up in energy-sensitive, photon-counting detectors and level-crossing of shot noise

    Science.gov (United States)

    Roessl, Ewald; Bartels, Matthias; Daerr, Heiner; Proksa, Roland

    2016-03-01

    Shot noise processes are omnipresent in physics and many of their properties have been extensively studied in the past, including the particular problem of level crossing of shot noise. Energy-sensitive, photon-counting detectors using comparators to discriminate pulse-heights are currently heavily investigated for medical applications, e.g. for x-ray computed tomography and x-ray mammography. Surprisingly, no mention of the close relation between the two topics can be found in the literature on photon-counting detectors. In this paper, we point out the close analogy between level crossing of shot noise and the problem of determining count rates of photon- counting detectors subject to pulse pile-up. The latter is very relevant for obtaining precise forward models for photon-counting detectors operated under conditions of very high x-ray flux employed in clinical x-ray computed tomography. Although several attempts have been made to provide reasonably accurate, approximative models for the registered number of counts in x-ray detectors under conditions of high flux and arbitrary x-ray spectra, see, e.g., no exact, analytic solution is given in the literature for general continuous pulse shapes. In this paper we present such a solution for arbitrary response functions, x-ray spectra and continuous pulse shapes based on a result from the theory of level crossing. We briefly outline the theory of level crossing including the famous Rice theorem and translate from the language of level crossing to the language of photon-counting detection.

  8. Dual adaptive statistical approach for quantitative noise reduction in photon-counting medical imaging: application to nuclear medicine images.

    Science.gov (United States)

    Hannequin, Pascal Paul

    2015-06-07

    Noise reduction in photon-counting images remains challenging, especially at low count levels. We have developed an original procedure which associates two complementary filters using a Wiener-derived approach. This approach combines two statistically adaptive filters into a dual-weighted (DW) filter. The first one, a statistically weighted adaptive (SWA) filter, replaces the central pixel of a sliding window with a statistically weighted sum of its neighbors. The second one, a statistical and heuristic noise extraction (extended) (SHINE-Ext) filter, performs a discrete cosine transformation (DCT) using sliding blocks. Each block is reconstructed using its significant components which are selected using tests derived from multiple linear regression (MLR). The two filters are weighted according to Wiener theory. This approach has been validated using a numerical phantom and a real planar Jaszczak phantom. It has also been illustrated using planar bone scintigraphy and myocardial single-photon emission computed tomography (SPECT) data. Performances of filters have been tested using mean normalized absolute error (MNAE) between the filtered images and the reference noiseless or high-count images.Results show that the proposed filters quantitatively decrease the MNAE in the images and then increase the signal-to-noise Ratio (SNR). This allows one to work with lower count images. The SHINE-Ext filter is well suited to high-size images and low-variance areas. DW filtering is efficient for low-size images and in high-variance areas. The relative proportion of eliminated noise generally decreases when count level increases. In practice, SHINE filtering alone is recommended when pixel spacing is less than one-quarter of the effective resolution of the system and/or the size of the objects of interest. It can also be used when the practical interest of high frequencies is low. In any case, DW filtering will be preferable.The proposed filters have been applied to nuclear

  9. Acousto-optic multiphoton laser scanning microscopy and multiphoton photon counting spectroscopy: Applications and implications for optical neurobiology

    Science.gov (United States)

    Iyer, Vijay

    Multiphoton excitation of molecular probes has become an important tool in experimental neurobiology owing to the intrinsic optical sectioning and low light scattering it affords. Using molecular functional indicators, multiphoton excitation allows physiological signals within single neurons to be observed from within living brain tissue. Ideally, it would be possible to record from multiple sites located throughout the elaborately branching dendritic arbors, in order to study the correlations of structure and function both within and across experiments. However, existing multiphoton microscope systems based on scanning mirrors do not allow optical recordings to be obtained from more than a handful of sites simultaneously at the high rates required to capture the fast physiological signals of interest (>100Hz for Ca2+ signals, >1kHz for membrane potential transients). In order to overcome this limitation, two-dimensional acousto-optic deflection was employed, to allow an ultrafast laser beam suited for multiphoton excitation to be rapidly repositioned with low latency (˜15mus). This supports a random-access scanning mode in which the beam can repeatedly visit a succession of user-selected sites of interest within the microscope's field-of-view at high rates, with minimal sacrifice of pixel dwell time. This technique of acousto-optic multiphoton laser scanning microscope (AO-MPLSM) was demonstrated to allow the spatial profile of signals arising in response to physiological stimulation to be rapidly mapped. Means to compensate or avoid problems of dispersion which have hampered AO-MPLSM in the past are presented, with the latter being implemented. Separately, the combination of photon counting detection with multiphoton excitation, termed generally multiphoton photon counting spectroscopy (MP-PCS), was also considered, with particular emphasis on the technique of fluorescence correlation spectroscopy (FCS). MP-PCS was shown to allow information about molecular

  10. On reachable energy resolution of SiPM based scintillation counters for X-ray detection

    Science.gov (United States)

    Kuper, K. E.; Oleynikov, V. P.; Porosev, V. V.; Savinov, G. A.; Drozdowski, W.

    2017-01-01

    Presently, silicon photomultipliers (SiPMs) are very attractive devices to replace photomultipliers for light detection in many different fields. For example, they could be used in detectors of photons with energies of 20-150 keV for medical and nondestructive testing applications. The small size and high electron gain of SiPMs make them very attractive candidates for pixelated X-ray detectors operating in a photon counting mode. In this research we evaluated the detector performance that can be reached with up-to-date Lu-based scintillators. Application of LYSO:Ce and LFS-3 scintillators provides high count rate capability because of a short scintillator decay time of ~ 40 ns but enables reaching just a moderate energy resolution. Meanwhile, with a LuYAG:Pr scintillator of quite low non-proportionality one can attain much better energy resolution at a reduced rate.

  11. A real-time noise filtering strategy for photon counting 3D imaging lidar.

    Science.gov (United States)

    Zhang, Zijing; Zhao, Yuan; Zhang, Yong; Wu, Long; Su, Jianzhong

    2013-04-22

    For a direct-detection 3D imaging lidar, the use of Geiger mode avalanche photodiode (Gm-APD) could greatly enhance the detection sensitivity of the lidar system since each range measurement requires a single detected photon. Furthermore, Gm-APD offers significant advantages in reducing the size, mass, power and complexity of the system. However the inevitable noise, including the background noise, the dark count noise and so on, remains a significant challenge to obtain a clear 3D image of the target of interest. This paper presents a smart strategy, which can filter out false alarms in the stage of acquisition of raw time of flight (TOF) data and obtain a clear 3D image in real time. As a result, a clear 3D image is taken from the experimental system despite the background noise of the sunny day.

  12. Performance of a compact position-sensitive photon counting detector with image charge coupling to an air-side anode

    Science.gov (United States)

    Jagutzki, O.; Czasch, A.; Schössler, S.

    2013-05-01

    We discuss a novel micro-channel plate (MCP) photomultiplier with resistive screen (RS-PMT) as a detection device for space- and time-correlated single photon counting, illustrated by several applications. The photomultiplier tube resembles a standard image intensifier device. However, the rear phosphor screen is replaced by a ceramic "window" with resistive coating. The MCP output is transferred through the ceramic plate to the read-out electrode (on the air side) via capacity-coupling of the image charge. This design allows for an easy reconfiguration of the read-out electrode (e.g. pixel, charge-sharing, cross-strip, delay-line) without breaking the vacuum for optimizing the detector performance towards a certain task. It also eases the design and manufacturing process of such a multi-purpose photomultiplier tube. Temporal and spatial resolutions well below 100 ps and 100 microns, respectively, have been reported at event rates as high as 1 MHz, for up to 40 mm effective detection diameter. In this paper we will discuss several applications like wide-field fluorescence microscopy and dual γ/fast-neutron radiography for air cargo screening and conclude with an outlook on large-area detectors for thermal neutrons based on MCPs.

  13. 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.

  14. Medipix3: A 64 k pixel detector readout chip working in single photon counting mode with improved spectrometric performance

    CERN Document Server

    Ballabriga, R; Wong, W; Heijne, E; Campbell, M; Llopart, X

    2011-01-01

    Medipix3 is a 256 x 256 channel hybrid pixel detector readout chip working in a single photon counting mode with a new inter-pixel architecture, which aims to improve the energy resolution in pixelated detectors by mitigating the effects of charge sharing between channels. Charges are summed in all 2 x 2 pixel clusters on the chip and a given hit is allocated locally to the pixel summing circuit with the biggest total charge on an event-by-event basis. Each pixel contains also two 12-bit binary counters with programmable depth and overflow control. The chip is configurable such that either the dimensions of each detector pixel match those of one readout pixel or detector pixels are four times greater in area than the readout pixels. In the latter case, event-by-event summing is still possible between the larger pixels. Each pixel has around 1600 transistors and the analog static power consumption is below 15 mu W in the charge summing mode and 9 mu W in the single pixel mode. The chip has been built in an 8-m...

  15. Soft X-ray detection and photon counting spectroscopy with commercial 4H-SiC Schottky photodiodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, S., E-mail: Shifan.Zhao@sussex.ac.uk; Gohil, T.; Lioliou, G.; Barnett, A.M.

    2016-09-11

    The results of electrical characterisation and X-ray detection measurements of two different active area (0.06 mm{sup 2} and 0.5 mm{sup 2}) commercial 4H-SiC Schottky photodiodes at room temperature are reported. The devices exhibited low dark currents (less than 10 pA) even at a high electric field strengths (403 kV/cm for 0.06 mm{sup 2} diodes; 227 kV/cm for 0.5 mm{sup 2} diodes). The results of the X-ray measurements indicate that the diodes can be used as photon counting spectroscopic X-ray detectors with modest energy resolutions: FWHM at 5.9 keV of 1.8 keV and 3.3 keV, for the 0.06 mm{sup 2} and 0.5 mm{sup 2} devices, respectively. Noise analysis of the photodiodes coupled to a custom low noise charge sensitive preamplifier is also presented.

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

    Science.gov (United States)

    Peronio, P.; Acconcia, G.; Rech, I.; Ghioni, M.

    2015-11-01

    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.

  17. A high-resolution imaging technique using a whole-body, research photon counting detector CT system

    Science.gov (United States)

    Leng, S.; Yu, Z.; Halaweish, A.; Kappler, S.; Hahn, K.; Henning, A.; Li, Z.; Lane, J.; Levin, D. L.; Jorgensen, S.; Ritman, E.; McCollough, C.

    2016-03-01

    A high-resolution (HR) data collection mode has been introduced to a whole-body, research photon-counting-detector CT system installed in our laboratory. In this mode, 64 rows of 0.45 mm x 0.45 mm detector pixels were used, which corresponded to a pixel size of 0.25 mm x 0.25 mm at the iso-center. Spatial resolution of this HR mode was quantified by measuring the MTF from a scan of a 50 micron wire phantom. An anthropomorphic lung phantom, cadaveric swine lung, temporal bone and heart specimens were scanned using the HR mode, and image quality was subjectively assessed by two experienced radiologists. High spatial resolution of the HR mode was evidenced by the MTF measurement, with 15 lp/cm and 20 lp/cm at 10% and 2% modulation. Images from anthropomorphic phantom and cadaveric specimens showed clear delineation of small structures, such as lung vessels, lung nodules, temporal bone structures, and coronary arteries. Temporal bone images showed critical anatomy (i.e. stapes superstructure) that was clearly visible in the PCD system. These results demonstrated the potential application of this imaging mode in lung, temporal bone, and vascular imaging. Other clinical applications that require high spatial resolution, such as musculoskeletal imaging, may also benefit from this high resolution mode.

  18. Fast and precise algorithms for calculating offset correction in single photon counting ASICs built in deep sub-micron technologies

    Science.gov (United States)

    Maj, P.

    2014-07-01

    An important trend in the design of readout electronics working in the single photon counting mode for hybrid pixel detectors is to minimize the single pixel area without sacrificing its functionality. This is the reason why many digital and analog blocks are made with the smallest, or next to smallest, transistors possible. This causes a problem with matching among the whole pixel matrix which is acceptable by designers and, of course, it should be corrected with the use of dedicated circuitry, which, by the same rule of minimizing devices, suffers from the mismatch. Therefore, the output of such a correction circuit, controlled by an ultra-small area DAC, is not only a non-linear function, but it is also often non-monotonic. As long as it can be used for proper correction of the DC operation points inside each pixel, it is acceptable, but the time required for correction plays an important role for both chip verification and the design of a big, multi-chip system. Therefore, we present two algorithms: a precise one and a fast one. The first algorithm is based on the noise hits profiles obtained during so called threshold scan procedures. The fast correction procedure is based on the trim DACs scan and it takes less than a minute in a SPC detector systems consisting of several thousands of pixels.

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

    CERN Document Server

    Sottile, G; Agnetta, G; Belluso, M; Billotta, S; Biondo, B; Bonanno, G; Catalano, O; Giarrusso, S; Grillo, A; Impiombato, D; La Rosa, G; Maccarone, M C; Mangano, A; Marano, D; Mineo, T; Segreto, A; Strazzeri, E; Timpanaro, M C; 10.1016/j.nuclphysbps.2013.05.040

    2013-01-01

    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.

  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. Method to improve the signal-to-noise ratio of photon-counting chirped amplitude modulation ladar.

    Science.gov (United States)

    Zhang, Zijing; Wu, Long; Zhang, Yong; Zhao, Yuan

    2013-01-10

    Photon-counting chirped amplitude modulation (PCCAM) ladar employs Geiger mode avalanche photodiode as a detector. After the detector corresponding to the echo signal is reflected from an object or target, the modulation depth (MD) of the detection outputs has some certain loss relative to that of the transmitting signal. The signal-to-noise ratio (SNR) of PCCAM ladar is mainly determined by the MD of detection outputs of the echo signal. There is a proper echo signal intensity that can decrease the MD loss and improve the SNR of the ladar receiver. In this paper, an improved PCCAM ladar system is presented, which employs an echo signal intensity optimization strategy with an iris diaphragm under different signal and noise intensities. The improved system is demonstrated with the background noise of a sunny day and the echo signal intensity from 0.1 to 10 counts/ns. The experimental results show that it can effectively improve the SNR of the ladar receiver compared with the typical PCCAM ladar system. © 2013 Optical Society of America

  2. The detective quantum efficiency of photon-counting x-ray detectors using cascaded-systems analyses

    Energy Technology Data Exchange (ETDEWEB)

    Tanguay, Jesse [Robarts Research Institute and Department of Medical Biophysics, Western University, London, Ontario N6A 5C1 (Canada); Yun, Seungman [Biomedical Engineering Program, Western University, London, Ontario N6A 5C1 (Canada); School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Kim, Ho Kyung [School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Cunningham, Ian A. [Robarts Research Institute, Department of Medical Biophysics, and Biomedical Engineering Program, Western University, London, Ontario N6A 5C1 (Canada)

    2013-04-15

    Purpose: Single-photon counting (SPC) x-ray imaging has the potential to improve image quality and enable new advanced energy-dependent methods. The purpose of this study is to extend cascaded-systems analyses (CSA) to the description of image quality and the detective quantum efficiency (DQE) of SPC systems. Methods: Point-process theory is used to develop a method of propagating the mean signal and Wiener noise-power spectrum through a thresholding stage (required to identify x-ray interaction events). The new transfer relationships are used to describe the zero-frequency DQE of a hypothetical SPC detector including the effects of stochastic conversion of incident photons to secondary quanta, secondary quantum sinks, additive noise, and threshold level. Theoretical results are compared with Monte Carlo calculations assuming the same detector model. Results: Under certain conditions, the CSA approach can be applied to SPC systems with the additional requirement of propagating the probability density function describing the total number of image-forming quanta through each stage of a cascaded model. Theoretical results including DQE show excellent agreement with Monte Carlo calculations under all conditions considered. Conclusions: Application of the CSA method shows that false counts due to additive electronic noise results in both a nonlinear image signal and increased image noise. There is a window of allowable threshold values to achieve a high DQE that depends on conversion gain, secondary quantum sinks, and additive noise.

  3. The detective quantum efficiency of photon-counting x-ray detectors using cascaded-systems analyses.

    Science.gov (United States)

    Tanguay, Jesse; Yun, Seungman; Kim, Ho Kyung; Cunningham, Ian A

    2013-04-01

    Single-photon counting (SPC) x-ray imaging has the potential to improve image quality and enable new advanced energy-dependent methods. The purpose of this study is to extend cascaded-systems analyses (CSA) to the description of image quality and the detective quantum efficiency (DQE) of SPC systems. Point-process theory is used to develop a method of propagating the mean signal and Wiener noise-power spectrum through a thresholding stage (required to identify x-ray interaction events). The new transfer relationships are used to describe the zero-frequency DQE of a hypothetical SPC detector including the effects of stochastic conversion of incident photons to secondary quanta, secondary quantum sinks, additive noise, and threshold level. Theoretical results are compared with Monte Carlo calculations assuming the same detector model. Under certain conditions, the CSA approach can be applied to SPC systems with the additional requirement of propagating the probability density function describing the total number of image-forming quanta through each stage of a cascaded model. Theoretical results including DQE show excellent agreement with Monte Carlo calculations under all conditions considered. Application of the CSA method shows that false counts due to additive electronic noise results in both a nonlinear image signal and increased image noise. There is a window of allowable threshold values to achieve a high DQE that depends on conversion gain, secondary quantum sinks, and additive noise.

  4. Soft X-ray detection and photon counting spectroscopy with commercial 4H-SiC Schottky photodiodes

    Science.gov (United States)

    Zhao, S.; Gohil, T.; Lioliou, G.; Barnett, A. M.

    2016-09-01

    The results of electrical characterisation and X-ray detection measurements of two different active area (0.06 mm2 and 0.5 mm2) commercial 4H-SiC Schottky photodiodes at room temperature are reported. The devices exhibited low dark currents (less than 10 pA) even at a high electric field strengths (403 kV/cm for 0.06 mm2 diodes; 227 kV/cm for 0.5 mm2 diodes). The results of the X-ray measurements indicate that the diodes can be used as photon counting spectroscopic X-ray detectors with modest energy resolutions: FWHM at 5.9 keV of 1.8 keV and 3.3 keV, for the 0.06 mm2 and 0.5 mm2 devices, respectively. Noise analysis of the photodiodes coupled to a custom low noise charge sensitive preamplifier is also presented.

  5. Analysis of a random modulation single photon counting differential absorption lidar system for space-borne atmospheric CO2 sensing.

    Science.gov (United States)

    Ai, X; Pérez-Serrano, A; Quatrevalet, M; Nock, R W; Dahnoun, N; Ehret, G; Esquivias, I; Rarity, J G

    2016-09-05

    The ability to observe the Earth's carbon cycles from space provides scientists an important tool to analyze climate change. Current proposed systems are mainly based on pulsed integrated path differential absorption lidar, in which two high energy pulses at different wavelengths interrogate the atmosphere sequentially for its transmission properties and are back-scattered by the ground. In this work an alternative approach based on random modulation single photon counting is proposed and analyzed; this system can take advantage of a less power demanding semiconductor laser in intensity modulated continuous wave operation, benefiting from a better efficiency, reliability and radiation hardness. Our approach is validated via numerical simulations considering current technological readiness, demonstrating its potential to obtain a 1.5 ppm retrieval precision for 50 km averaging with 2.5 W average power in a space-borne scenario. A major limiting factor is the ambient shot noise, if ultra-narrow band filtering technology could be applied, 0.5 ppm retrieval precision would be attainable.

  6. 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...

  7. Low-Afterglow, High-Refractive-Index Liquid Scintillators for Fast-Neutron Spectrometry and Imaging Applications

    CERN Document Server

    Lauck, Ronald; Bromberger, Benjamin; Dangendorf, Volker; Goldberg, Mark B; Mor, Ilan; Tittelmeier, Kai; Vartsky, David

    2009-01-01

    For ion and neutron spectrometry and imaging applications at a high intensity pulsed laser facility, fast liquid scintillators with very low afterglow are required. Furthermore, neutron imaging with fiber (or liquid-core) capillary arrays calls for scintillation materials with high refractive index. To this end, we have examined various combinations of established mixtures of fluors and solvents, that were enriched alternatively with nitrogen or oxygen. Dissolved molecular oxygen is known to be a highly effective quenching agent, that efficiently suppresses the population of the triplet states in the fluor, which are primarily responsible for the afterglow. For measuring the glow curves of scintillators, we have employed the time-correlated single photon counting (TCSPC) technique, characterized by high dynamic range of several orders of magnitude in light intensity. In this paper we outline the application for the fast scintillators, briefly present the scintillation mechanism in liquids, describe our specif...

  8. MABEL Photon-Counting Laser Altimetry Data for ICESat-2 Simulations and Development

    Science.gov (United States)

    Brunt, K. M.; Neumann, T.; Walsh, K. M.; Markus, T.

    2013-12-01

    Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) is scheduled to launch in 2016 and will carry the Advanced Topographic Laser Altimeter System (ATLAS), which represents a new approach to space-borne determination of surface elevation. Given the new technology of ATLAS, an airborne instrument, the Multiple Altimeter Beam Experimental Lidar (MABEL), was developed to provide data needed for 1) algorithm development and 2) to simulate key elements of this new sampling strategy. Instrument precision is critical to satellite algorithm development. We present precision estimates for MABEL surface elevations associated with 2011-2012 surveys. The greatest changes in elevation in Greenland and Antarctica are happening along the margins of the ice sheets where the surface frequently has significant slopes. For this reason the ICESat-2 mission utilizes pairs of laser altimeter beams that are perpendicular to the flight direction in order to extract slope information in addition to elevation. We present local slopes as determined by MABEL and compare them to those determined by the Airborne Topographic Mapper (ATM) over the same flight lines on the Greenland Ice Sheet. Results from MABEL suggest that 1) MABEL precision is within the design goals aimed at algorithm development and 2) ICESat-2 beam geometry is appropriate for the determination of slope on ~90 m spatial scales, a measurement that will be fundamental to deconvolving the effects of surface slope from the ice-sheet surface change derived from ICESat-2.

  9. 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)

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

    Science.gov (United States)

    Schlosser, D. M.; Huth, M.; Hartmann, R.; Abboud, A.; Send, S.; Conka-Nurdan, T.; Shokr, M.; Pietsch, U.; Strüder, L.

    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 57Co source.

  11. Magnetic iron oxide nanoparticles for the collection and direct measurement of adsorbed alpha-emitting radionuclides from environmental waters by liquid scintillation analysis

    Energy Technology Data Exchange (ETDEWEB)

    O' Hara, Matthew J.; Addleman, R. Shane

    2017-01-01

    Radioactive contamination in the environment, be it from accidental or intentional release, can create an urgent need to assess water and food supplies, the environment, and monitor human health. Alpha-emitting radionuclides represent the most ionizing, and therefore the most damaging, form of radiation when internalized. Additionally, because of its ease of energy attenuation in solids or liquids, alpha emissions cannot be reliably monitored using non-destructive means. In the event of such an emergency, rapid and efficient methods will be needed to screen scores of samples (food, water, and human excreta) within a short time window. Unfortunately, the assay of alpha-emitting radionuclides using traditional radioanalytical methods is typically labor intensive and time consuming. The creation of analytical counting sources typically requires a series of chemical treatment steps to achieve well performing counting sources. In an effort to devise radioanalytical methods that are fast, require little labor, and minimize the use of toxic or corrosive agents, researchers at PNNL have evaluated magnetite (Fe3O4) nanoparticles as extracting agents for alpha-emitting radionuclides from chemically unmodified aqueous systems. It is demonstrated that bare magnetic nanoparticles exhibit high affinity for representative α-emitting radionuclides (241Am and 210Po) from representative aqueous matrices: river and ground water. Furthermore, use of the magnetic properties of these materials to concentrate the sorbed analyte from the bulk aqueous solution has been demonstrated. The nanoparticle concentrate can be either directly dispensed into scintillation cocktail, or first dissolved and then added to scintillation cocktail as a solution for alpha emission assay by liquid scintillation analysis. Despite the extreme quench caused by the metal oxide suspensions, the authors have demonstrated that quench correction features available on modern liquid scintillation analyzers can be

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

    Science.gov (United States)

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

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hyo-Min; Ding, Huanjun; Molloi, Sabee, E-mail: symolloi@uci.edu [Department of Radiological Sciences, University of California, Irvine, California 92697 (United States); Barber, William C.; Iwanczyk, Jan S. [DxRay Inc., Northridge, California 91324 (United States)

    2014-09-15

    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. A{sup 109}Cd 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/mm{sup 2}) has been obtained (1 million cps per 100 × 100 μm pixel). The electrical noise floor was less than 4 keV. The

  14. Spatio-energetic cross-talks in photon counting detectors: detector model and correlated Poisson data generator

    Science.gov (United States)

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

    2016-03-01

    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 two pixels. This is called double-counting with charge sharing. The output of individual PCD pixel is Poisson distributed integer counts; however, the outputs of adjacent pixels are correlated due to double-counting. Major problems are the lack of detector noise model for the spatio-energetic crosstalk and the lack of an efficient simulation tool. Monte Carlo simulation can accurately simulate these phenomena and produce noisy data; however, it is not computationally efficient. In this study, we developed a new detector model and implemented into an efficient software simulator which uses a Poisson random number generator to produce correlated noisy integer counts. The detector model takes the following effects into account effects: (1) detection efficiency and incomplete charge collection; (2) photoelectric effect with total absorption; (3) photoelectric effect with fluorescence x-ray emission and re-absorption; (4) photoelectric effect with fluorescence x-ray emission which leaves PCD completely; and (5) electric noise. The model produced total detector spectrum similar to previous MC simulation data. The model can be used to predict spectrum and correlation with various different settings. The simulated noisy data demonstrated the expected performance: (a) data were integers; (b) the mean and covariance matrix was close to the target values; (c) noisy data generation was very efficient

  15. Reduction of metal artifact in single photon-counting computed tomography by spectral-driven iterative reconstruction technique.

    Directory of Open Access Journals (Sweden)

    Radin A Nasirudin

    Full Text Available The exciting prospect of Spectral CT (SCT using photon-counting detectors (PCD will lead to new techniques in computed tomography (CT that take advantage of the additional spectral information provided. We introduce a method to reduce metal artifact in X-ray tomography by incorporating knowledge obtained from SCT into a statistical iterative reconstruction scheme. We call our method Spectral-driven Iterative Reconstruction (SPIR.The proposed algorithm consists of two main components: material decomposition and penalized maximum likelihood iterative reconstruction. In this study, the spectral data acquisitions with an energy-resolving PCD were simulated using a Monte-Carlo simulator based on EGSnrc C++ class library. A jaw phantom with a dental implant made of gold was used as an object in this study. A total of three dental implant shapes were simulated separately to test the influence of prior knowledge on the overall performance of the algorithm. The generated projection data was first decomposed into three basis functions: photoelectric absorption, Compton scattering and attenuation of gold. A pseudo-monochromatic sinogram was calculated and used as input in the reconstruction, while the spatial information of the gold implant was used as a prior. The results from the algorithm were assessed and benchmarked with state-of-the-art reconstruction methods.Decomposition results illustrate that gold implant of any shape can be distinguished from other components of the phantom. Additionally, the result from the penalized maximum likelihood iterative reconstruction shows that artifacts are significantly reduced in SPIR reconstructed slices in comparison to other known techniques, while at the same time details around the implant are preserved. Quantitatively, the SPIR algorithm best reflects the true attenuation value in comparison to other algorithms.It is demonstrated that the combination of the additional information from Spectral CT and

  16. Optimized design of a TOF laser range finder based on time-correlated single-photon counting

    Science.gov (United States)

    Wang, Huanqin; Yang, Yixin; Huang, Zhe; Cao, YangYang; Gui, Huaqiao

    2014-11-01

    A time-of-flight (TOF) laser range finder based on time-correlated single photon counting (TCSPC) has been developed. By using a Geiger-mode avalanche photodiode (G-APD) with the ability of detecting single-photon events and Time-to-Digital Converter (TDC) with picosecond resolution, a good linearity with 4.5 cm range precision can be achieved in the range of 1-10 m. This paper highlights a significant advance in improving the key parameters of this system, including the range precision and measurement dynamic range. In our experiments, it was found that both of the precision and the measurement dynamic range were limited by the signal to noise rate (SNR) and the inherent jitter of system. The range precision can be improved by enhancing the SNR of system. However, when the SNR is high enough, the main factors affecting the range precision will turn into the inherent jitter, which makes the range precision can not be improved infinitely. Moreover, the inherent jitter generated by pulsed laser and the signal processing module has been measured, and its influence on the system performance has also been discussed. Taking all of these factors into account, some optimized designs have been proposed to improve range precision and dynamic range simultaneously. The final experiment results show that, after all of these optimization designs, the range precision of system is better than 1.2 cm and the measurement dynamic range is enlarged to 54 m when the sampling time is as short as 1 ms, which is sufficient for many applications of 3D object recognition, computer vision, reverse engineering and virtual reality.

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

    Science.gov (United States)

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

    2015-12-01

    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: ṡ processing the signal with the possibility of total charge reconstruction (by connecting with the adjacent pixels), ṡ a comparison of certain pixel amplitude to its 8 neighbours, ṡ 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), ṡ 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 together

  18. Comparison of quantitative k-edge empirical estimators using an energy-resolved photon-counting detector

    Science.gov (United States)

    Zimmerman, Kevin C.; Gilat Schmidt, Taly

    2016-03-01

    Using an energy-resolving photon counting detector, the amount of k-edge material in the x-ray path can be estimated using a process known as material decomposition. However, non-ideal effects within the detector make it difficult to accurately perform this decomposition. This work evaluated the k-edge material decomposition accuracy of two empirical estimators. A neural network estimator and a linearized maximum likelihood estimator with error look-up tables (A-table method) were evaluated through simulations and experiments. Each estimator was trained on system-specific calibration data rather than specific modeling of non-ideal detector effects or the x-ray source spectrum. Projections through a step-wedge calibration phantom consisting of different path lengths through PMMA, aluminum, and a k-edge material was used to train the estimators. The estimators were tested by decomposing data acquired through different path lengths of the basis materials. The estimators had similar performance in the chest phantom simulations with gadolinium. They estimated four of the five densities of gadolinium with less than 2mg/mL bias. The neural networks estimates demonstrated lower bias but higher variance than the A-table estimates in the iodine contrast agent simulations. The neural networks had an experimental variance lower than the CRLB indicating it is a biased estimator. In the experimental study, the k-edge material contribution was estimated with less than 14% bias for the neural network estimator and less than 41% bias for the A-table method.

  19. Photon counting performance measurements of transfer electron InGaAsP photocathode hybrid photomultiplier tubes at 1064 nm wavelength

    Science.gov (United States)

    Sun, Xiaoli; Krainak, Michael A.; Hasselbrack, William B.; La Rue, Ross A.

    2007-05-01

    We report the test results of a hybrid photomultiplier tube (HPMT) with a transfer electron (TE) InGaAsP photocathode and GaAs Schottky avalanche photodiode (APD) anode. Unlike Geiger mode InGaAsP APDs, these HPMTs (also known as intensified photodiode (IPD), vacuum APD, or hybrid photodetector) operate in linear mode without the need for quenching and gating. Their greatest advantages are wide dynamic range, high speed, large photosensitive area, and potential for photon counting and analog detection dual mode operation. The photon detection efficiency we measured was 25% at 1064 nm wavelength with a dark count rate of 60,000/s at -22 degrees Celsius. The output pulse width in response to a single photon detection is about 0.9 ns. The maximum count rate was 90 Mcts/s and was limited solely by the speed of the discriminator used in the measurement (10 ns dead time). The spectral response of these devices extended from 900 to 1300 nm. We also measured the HPMT response to 60 ps laser pulses. The average output pulse amplitude increased monotonically with the input pulse energy, which suggested that we can resolve photon number in an incident pulse. The jitter of the HPMT output was found to be about 0.5 ns standard deviation and depended on bias voltage applied to the TE photocathode. To our knowledge, these HPMTs are the most sensitive non gating photon detectors at 1064 nm wavelength, and they will have many applications in laser altimeters, atmospheric lidars, and free space laser communication systems.

  20. Calibration of a single-photon counting detectors without the need of input photon flux calibration (Conference Presentation)

    Science.gov (United States)

    Gerrits, Thomas

    2017-05-01

    Calibration of fiber-coupled single-photon detectors usually requires knowledge of the input photon flux inside the fiber and/or knowledge of the linearity of a reference power meter. Many approaches have been presented in the past to accurately measure the photon detection probability of a single photon detector [1-6]. Under certain assumptions, one can utilize waveguide-coupled single photon detectors and a series of photon-counting measurements and a single-photon source to calibrate the detection efficiency of a single photon detector without the need of a reference power meter and the knowledge of the incoming photon flux. Here, this method is presented. Furthermore, if a reference detector is used, the detection efficiency of all evanescently coupled waveguide detectors can be measured, and the measurement outcome does not depend on splicing or fiber connection losses within in the setup, i.e., the measurement is setup-independent. In addition, the method, when using a reference detector, can be utilized to measure and distinguish between the absorption of a waveguide-coupled single photon detector and its internal detection efficiency. [1] A. J. Miller et al, Opt. Express 19, 9102-9110 (2011) [2] I. Muller et al., Metrologia 51, S329 (2014). [3] A. L. Migdall, Instrumentation and Measurement, IEEE Transactions on 50, 478-481 (2001). [4] S. V. Polyakov, A. L. Migdall, Optics Express 15, 1390-1407 (2007). [5] A. Avella et al., Optics Express 19, 23249-23257 (2011). [6] T. Lunghi et al., Opt. Express 22, 18078-18092 (2014)

  1. X-ray machine for general radiology and mammography based on room temperature solid state detector coupled to photon-counting electronics. Evaluation of results

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Bayo, J.; Sentis, M.; Tortajada, M.; Ganau, S.; Tortajada, L. [UDIAT CD Sabadell, Barcelona (Spain); Chmeissani, M.; Blanchot, G.; Garcia, J.; Maiorino, M.; Puigdengoles, C. [Centre Inst. de Fisica d' altes energies, UAB Campus Bellaterra, Barcelona (Spain); Lozano, M.; Martinez, R.; Pellegrini, G.; Ullan, M. [CNM-CSIC UAB, Campus Bellaterra, Barcelona (Spain); Kainberger, F. [Univ. of Vienna, (Austria); Montage, J.P. [Hopital d' enfant Armand Trousseau, Paris (France)

    2007-06-15

    Dear-Mama (detection of early markers in mammography) is an EU-funded project (FP5) to develop an X-ray medical imaging device based on a room temperature solid-state pixel detector coupled to photon-counting readout electronics via bump bonding. The technology used allows signal-to-noise enhancing and thus enables detection of low-contrast anomalies such as micro-calcifications. In this paper we present the results of the preliminary clinical evaluation. (orig.)

  2. A fundamental method to determine the signal-to-noise ratio (SNR) and detective quantum efficiency (DQE) for a photon counting pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Michel, T. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany)]. E-mail: thilo.michel@physik.uni-erlangen.de; Anton, G. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Boehnel, M. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Durst, J. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Firsching, M. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Korn, A. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Kreisler, B. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Loehr, A. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Nachtrab, F. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Niederloehner, D. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Sukowski, F. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany); Takoukam Talla, P. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Strasse 1, 91058 Erlangen (Germany)

    2006-12-01

    We outline in this paper that the noise of a photon counting pixel detector depends on the detection efficiency and the average multiplicity of counts per interacting photon. We give a simple expression for the signal-to-noise ratio (SNR) and zero-frequency detective quantum efficiency (DQE). We describe a method to determine the DQE from measured data and to optimize the DQE as a function of energy threshold.

  3. Characterization of Heavy Oxide Inorganic Scintillator Crystals for Direct Detection of Fast Neutrons Based on Inelastic Scattering

    Science.gov (United States)

    2015-03-01

    emission of additional gamma photons that likewise cause scintillation [4]. The specific goals of this research are to:  explore the physics of fast ...reaction products are registered; also in the sense that, in the case of fast neutrons, moderation is normally required before the absorption event...various other forms of radiation, fast neutrons are the crux of the overall study, and every effort should be made to test with them. 39 LIST OF

  4. 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.

  5. 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

  6. Upgrade of the POLDI diffractometer with a ZnS(Ag)/6LiF scintillation detector read out with WLS fibers coupled to SiPMs

    OpenAIRE

    Mosset, J. -B.; Stoykov, A.; Davydov, V.; Hildebrandt, M.; Van Swygenhoven, H.; W. Wagner

    2013-01-01

    A thermal neutron detector based on ZnS(Ag)/6LiF scintillator, wavelength-shifting fibers (WLS) and silicon photomultipliers (SiPM) is under development at the Paul Scherrer Institute (PSI) for upgrading the POLDI instrument, a pulse-overlap diffractometer. The design of the detector is outlined, and the measurements performed on a single channel prototype are presented. An innovative signal processing system based on a photon counting approach is under development. Its principle of operation...

  7. Bolometric calibration of a superfluid $^3$He detector for Dark Matter search: direct measurement of the scintillated energy fraction for neutron, electron and muon events

    CERN Document Server

    Winkelmann, C B; Collin, E; Elbs, J; Godfrin, H; Krusius, M; Bunkov, Yu.M.

    2006-01-01

    We report on the calibration of a superfluid $^3$He bolometer developed for the search of non-baryonic Dark Matter. Precise thermometry is achieved by the direct measurement of thermal excitations using Vibrating Wire Resonators (VWRs). The heating pulses for calibration were produced by the direct quantum process of quasiparticle generation by other VWRs present. The bolometric calibration factor is analyzed as a function of temperature and excitation level of the sensing VWR. The calibration is compared to bolometric measurements of the nuclear neutron capture reaction and heat depositions by cosmic muons and low energy electrons. The comparison allows a quantitative estimation of the ultra-violet scintillation rate of irradiated helium, demonstrating the possibility of efficient electron recoil event rejection.

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

    Energy Technology Data Exchange (ETDEWEB)

    Fiorini, M., E-mail: fiorini@fe.infn.it [Università degli Studi di Ferrara and INFN Sezione di Ferrara (Italy); Andreotti, M.; Baldini, W.; Calabrese, R. [Università degli Studi di Ferrara and INFN Sezione di Ferrara (Italy); Carniti, P.; Cassina, L. [Università degli Studi di Milano Bicocca and INFN Sezione di Milano Bicocca (Italy); Cotta Ramusino, A. [Università degli Studi di Ferrara and INFN Sezione di Ferrara (Italy); Giachero, A.; Gotti, C. [Università degli Studi di Milano Bicocca and INFN Sezione di Milano Bicocca (Italy); Luppi, E. [Università degli Studi di Ferrara and INFN Sezione di Ferrara (Italy); Maino, M. [Università degli Studi di Milano Bicocca and INFN Sezione di Milano Bicocca (Italy); Malaguti, R. [Università degli Studi di Ferrara and INFN Sezione di Ferrara (Italy); Pessina, G. [Università degli Studi di Milano Bicocca and INFN Sezione di Milano Bicocca (Italy); Tomassetti, L. [Università degli Studi di Ferrara and INFN Sezione di Ferrara (Italy)

    2014-12-01

    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{sup 12} 1 MeV n{sub eq}/cm{sup 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{sup 14} cm{sup −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.

  9. Detecting liquid threats with x-ray diffraction imaging (XDi) using a hybrid approach to navigate trade-offs between photon count statistics and spatial resolution

    Science.gov (United States)

    Skatter, Sondre; Fritsch, Sebastian; Schlomka, Jens-Peter

    2016-05-01

    The performance limits were explored for an X-ray Diffraction based explosives detection system for baggage scanning. This XDi system offers 4D imaging that comprises three spatial dimensions with voxel sizes in the order of ~(0.5cm)3, and one spectral dimension for material discrimination. Because only a very small number of photons are observed for an individual voxel, material discrimination cannot work reliably at the voxel level. Therefore, an initial 3D reconstruction is performed, which allows the identification of objects of interest. Combining all the measured photons that scattered within an object, more reliable spectra are determined on the object-level. As a case study we looked at two liquid materials, one threat and one innocuous, with very similar spectral characteristics, but with 15% difference in electron density. Simulations showed that Poisson statistics alone reduce the material discrimination performance to undesirable levels when the photon counts drop to 250. When additional, uncontrolled variation sources are considered, the photon count plays a less dominant role in detection performance, but limits the performance also for photon counts of 500 and higher. Experimental data confirmed the presence of such non-Poisson variation sources also in the XDi prototype system, which suggests that the present system can still be improved without necessarily increasing the photon flux, but by better controlling and accounting for these variation sources. When the classification algorithm was allowed to use spectral differences in the experimental data, the discrimination between the two materials improved significantly, proving the potential of X-ray diffraction also for liquid materials.

  10. Development and calibration of a real-time airborne radioactivity monitor using direct gamma-ray spectrometry with two scintillation detectors.

    Science.gov (United States)

    Casanovas, R; Morant, J J; Salvadó, M

    2014-07-01

    The implementation of in-situ gamma-ray spectrometry in an automatic real-time environmental radiation surveillance network can help to identify and characterize abnormal radioactivity increases quickly. For this reason, a Real-time Airborne Radioactivity Monitor using direct gamma-ray spectrometry with two scintillation detectors (RARM-D2) was developed. The two scintillation detectors in the RARM-D2 are strategically shielded with Pb to permit the separate measurement of the airborne isotopes with respect to the deposited isotopes.In this paper, we describe the main aspects of the development and calibration of the RARM-D2 when using NaI(Tl) or LaBr3(Ce) detectors. The calibration of the monitor was performed experimentally with the exception of the efficiency curve, which was set using Monte Carlo (MC) simulations with the EGS5 code system. Prior to setting the efficiency curve, the effect of the radioactive source term size on the efficiency calculations was studied for the gamma-rays from (137)Cs. Finally, to study the measurement capabilities of the RARM-D2, the minimum detectable activity concentrations for (131)I and (137)Cs were calculated for typical spectra at different integration times.

  11. A neural network-based method for spectral distortion correction in photon counting x-ray CT

    Science.gov (United States)

    Touch, Mengheng; Clark, Darin P.; Barber, William; Badea, Cristian T.

    2016-08-01

    Spectral CT using a photon counting x-ray detector (PCXD) shows great potential for measuring material composition based on energy dependent x-ray attenuation. Spectral CT is especially suited for imaging with K-edge contrast agents to address the otherwise limited contrast in soft tissues. We have developed a micro-CT system based on a PCXD. This system enables both 4 energy bins acquisition, as well as full-spectrum mode in which the energy thresholds of the PCXD are swept to sample the full energy spectrum for each detector element and projection angle. Measurements provided by the PCXD, however, are distorted due to undesirable physical effects in the detector and can be very noisy due to photon starvation in narrow energy bins. To address spectral distortions, we propose and demonstrate a novel artificial neural network (ANN)-based spectral distortion correction mechanism, which learns to undo the distortion in spectral CT, resulting in improved material decomposition accuracy. To address noise, post-reconstruction denoising based on bilateral filtration, which jointly enforces intensity gradient sparsity between spectral samples, is used to further improve the robustness of ANN training and material decomposition accuracy. Our ANN-based distortion correction method is calibrated using 3D-printed phantoms and a model of our spectral CT system. To enable realistic simulations and validation of our method, we first modeled the spectral distortions using experimental data acquired from 109Cd and 133Ba radioactive sources measured with our PCXD. Next, we trained an ANN to learn the relationship between the distorted spectral CT projections and the ideal, distortion-free projections in a calibration step. This required knowledge of the ground truth, distortion-free spectral CT projections, which were obtained by simulating a spectral CT scan of the digital version of a 3D-printed phantom. Once the training was completed, the trained ANN was used to perform

  12. 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

  13. 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

    2017-07-06

    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

  14. 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).

  15. 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).

  16. 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.

  17. A photon-counting spatial-diversity-and-multiplexing MIMO scheme for Poisson atmospheric channels relying on Q-ary PPM.

    Science.gov (United States)

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

    2012-11-19

    A novel Photon-Counting Spatial-Diversity-and-Multiplexing (PC-SDM) scheme is proposed for high-speed Free-Space Optical (FSO) transmission over shot-noise limited Poisson channels experiencing turbulence-induced fading. In particular, Iterative Parallel Interference Cancellation (Iter-PIC) aided Q-ary Pulse Position Modulation (Q-PPM) is employed. Simulation results demonstrate that our proposed scheme exhibits a high integrity and a high throughput, while mitigating the effects of multi-stream interference and background radiation noise.

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

    Science.gov (United States)

    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.

    2014-12-01

    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 6×1012 1 MeV neq /cm2 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 1014 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.

  19. Trimming the threshold dispersion below 10 e-rms in a large area readout IC working in a single photon counting mode

    Science.gov (United States)

    Kmon, P.; Maj, P.; Gryboś, P.; Szczygieł, R.

    2016-01-01

    We present a new method of an in-pixel threshold dispersion correction implemented in a prototype readout integrated circuit (IC) operating in a single photon counting mode. The new threshold correction method was implemented in a readout IC of area 9.6× 14.9 mm2 containing 23552 square pixels with the pitch of 75 μm designed and fabricated in CMOS 130 nm technology. Each pixel of the IC consists of a charge sensitive amplifier, a shaper, two discriminators, two 14-bit counters and a low-area trim DACs for threshold correction. The user can either control the range of the trim DAC globally for all the pixels in the integrated circuit or modify the trim DACs characteristics locally in each pixel independently. Using a simulation tool based on the Monte-Carlo methods, we estimated how much we could improve the offset trimming by increasing the number of bits in the trim DACs or implementing additional bits in a pixel to modify the characteristics of the trim DACs. The measurements of our IC prototype show that it is possible to reduce the effective threshold dispersion in large-area single-photon counting chips below 10 electrons rms.

  20. 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.

  1. Chromatic X-Ray imaging with a fine pitch CdTe sensor coupled to a large area photon counting pixel ASIC

    CERN Document Server

    Bellazzini, R; Brez, A; Minuti, M; Pinchera, M; Mozzo, P

    2012-01-01

    An innovative X-ray imaging sensor with intrinsic digital characteristics is presented. It is based on Chromatic Photon Counting technology. The detector is able to count individually the incident X-ray photons and to separate them according to their energy (two 'color' images per exposure). The energy selection occurs in real time and at radiographic imaging speed (GHz global counting rate). Photon counting, color mode and a very high spatial resolution (more than 10 l.p./mm at MTF50) allow to obtain an optimal ratio between image quality and absorbed dose. The individual block of the imaging system is a two-side buttable semiconductor radiation detector made of a thin pixellated CdTe crystal (the sensor) coupled to a large area VLSI CMOS pixel ASIC. 1, 2, 4, 8 tile units have been built. The 8 tiles unit has 25cm x 2.5cm sensitive area. Results and images obtained from in depth testing of several configurations of the system are presented. The X-Ray imaging system is the technological platform of PIXIRAD Im...

  2. Optimization of K-edge imaging for vulnerable plaques using gold nanoparticles and energy resolved photon counting detectors: a simulation study.

    Science.gov (United States)

    Alivov, Yahya; Baturin, Pavlo; Le, Huy Q; Ducote, Justin; Molloi, Sabee

    2014-01-06

    We investigated the effect of different imaging parameters, such as dose, beam energy, energy resolution and the number of energy bins, on the image quality of K-edge spectral computed tomography (CT) of gold nanoparticles (GNP) accumulated in an atherosclerotic plaque. A maximum likelihood technique was employed to estimate the concentration of GNP, which served as a targeted intravenous contrast material intended to detect the degree of the plaque's inflammation. The simulation studies used a single-slice parallel beam CT geometry with an x-ray beam energy ranging between 50 and 140 kVp. The synthetic phantoms included small (3 cm in diameter) cylinder and chest (33 × 24 cm(2)) phantoms, where both phantoms contained tissue, calcium and gold. In the simulation studies, GNP quantification and background (calcium and tissue) suppression tasks were pursued. The x-ray detection sensor was represented by an energy resolved photon counting detector (e.g., CdZnTe) with adjustable energy bins. Both ideal and more realistic (12% full width at half maximum (FWHM) energy resolution) implementations of the photon counting detector were simulated. The simulations were performed for the CdZnTe detector with a pixel pitch of 0.5-1 mm, which corresponds to a performance without significant charge sharing and cross-talk effects. The Rose model was employed to estimate the minimum detectable concentration of GNPs. A figure of merit (FOM) was used to optimize the x-ray beam energy (kVp) to achieve the highest signal-to-noise ratio with respect to the patient dose. As a result, the successful identification of gold and background suppression was demonstrated. The highest FOM was observed at the 125 kVp x-ray beam energy. The minimum detectable GNP concentration was determined to be approximately 1.06 µmol mL(-1) (0.21 mg mL(-1)) for an ideal detector and about 2.5 µmol mL(-1) (0.49 mg mL(-1)) for a more realistic (12% FWHM) detector. The studies show the optimal

  3. Finding four decay components in Li glass and three decay components in CeBr{sub 3} scintillation light pulses in the temperature range from −30 °C to +50 °C by iterative subtraction of composite decays

    Energy Technology Data Exchange (ETDEWEB)

    Pausch, Johannes, E-mail: j.pausch15@imperial.ac.uk; Scherwinski, Falko; Stein, Jürgen

    2016-01-21

    Basic photon count statistics are considered in order to point out problems in the evaluation of decay times of scintillator light pulses. Furthermore, numerical aspects and problems are discussed for two numerical evaluation methods, the least squares fit of exponential decays and the iterative subtraction. Both are then applied to find four decay components in Li glass scintillator pulses and three decay components in CeBr{sub 3} scintillator pulses. Their temperature dependence and relative intensities in the range between −30 °C and +50 °C are presented.

  4. Experimental comparison of high-density scintillators for EMCCD-based gamma ray imaging.

    Science.gov (United States)

    Heemskerk, Jan W T; Kreuger, Rob; Goorden, Marlies C; Korevaar, Marc A N; Salvador, Samuel; Seeley, Zachary M; Cherepy, Nerine J; van der Kolk, Erik; Payne, Stephen A; Dorenbos, Pieter; Beekman, Freek J

    2012-07-21

    Detection of x-rays and gamma rays with high spatial resolution can be achieved with scintillators that are optically coupled to electron-multiplying charge-coupled devices (EMCCDs). These can be operated at typical frame rates of 50 Hz with low noise. In such a set-up, scintillation light within each frame is integrated after which the frame is analyzed for the presence of scintillation events. This method allows for the use of scintillator materials with relatively long decay times of a few milliseconds, not previously considered for use in photon-counting gamma cameras, opening up an unexplored range of dense scintillators. In this paper, we test CdWO₄ and transparent polycrystalline ceramics of Lu₂O₃:Eu and (Gd,Lu)₂O₃:Eu as alternatives to currently used CsI:Tl in order to improve the performance of EMCCD-based gamma cameras. The tested scintillators were selected for their significantly larger cross-sections at 140 keV ((99m)Tc) compared to CsI:Tl combined with moderate to good light yield. A performance comparison based on gamma camera spatial and energy resolution was done with all tested scintillators having equal (66%) interaction probability at 140 keV. CdWO₄, Lu₂O₃:Eu and (Gd,Lu)₂O₃:Eu all result in a significantly improved spatial resolution over CsI:Tl, albeit at the cost of reduced energy resolution. Lu₂O₃:Eu transparent ceramic gives the best spatial resolution: 65 µm full-width-at-half-maximum (FWHM) compared to 147 µm FWHM for CsI:Tl. In conclusion, these 'slow' dense scintillators open up new possibilities for improving the spatial resolution of EMCCD-based scintillation cameras.

  5. Combined scintillation detector for gamma dose rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Viererbl, L.; Novakova, O.; Jursova, L. (Tesla, Premysleni (Czechoslovakia). Vyzkumny Ustav Pristroju Jaderne Techniky)

    1990-01-01

    The specifications are described of a newly developed scintillation detector, essentially consisting of a plastic scintillator completed with inorganic scintillators ZnS(Ag) and NaI(Tl). The gamma dose rate is derived from the photomultiplier anode current. The composition and sizes of the scintillators and the capsule are selected so as to minimise the energy dependence errors and directional dependence errors of the detector response over a wide range of energies and/or angles. (author).

  6. Ultra-fast time-correlated single photon counting avalanche photodiodes for time-domain non-contact fluorescence diffuse optical tomography

    Science.gov (United States)

    Robichaud, Vincent; Lapointe, Éric; Bérubé-Lauzière, Yves

    2007-06-01

    Recent advances in the design and fabrication of avalanche photodiodes (APDs) and quenching circuits for timecorrelated single photon counting (TCSPC) have made available detectors with timing resolutions comparable to microchannel plate photomultiplier tubes (MCP-PMTs). The latter, were until recently the best TCSPC detectors in terms of temporal resolution (standard electronics fabrication processes in a near future. This will contribute to further decrease their price and ease their integration in complex multi-channel detection systems, as required in diuse optical imaging (DOI) and tomography (DOT). We present, to our knowledge for the first time, results which demonstrate that, despite their small sensitive area, TCSPC APDs can be used in time-domain (TD) DOT and more generally in TD DOI. With appropriate optical design of the detection channel, our experiments show that it is possible to obtain comparable measurements with APDs as with PMTs.

  7. 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.

  8. First detective quantum efficiency measurement of 500 {mu}m silicon hybrid pixel sensor with photon counting readout for X-ray medical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Surre, Benjamin [Laboratoire de Biophysique medicale, University of Auvergne, Clermont-Ferrand (France)]. E-mail: Benjamin.surre@u-clermontl.fr; Caria, Mario [Laboratoire de Biophysique medicale, University of Auvergne, Clermont-Ferrand (France); Chaput, Julien [Laboratoire de Biophysique medicale, University of Auvergne, Clermont-Ferrand (France); Hassoun, Thierry [Laboratoire de Biophysique medicale, University of Auvergne, Clermont-Ferrand (France); Laverroux, Fabien [Laboratoire de Biophysique medicale, University of Auvergne, Clermont-Ferrand (France); Sarry, Laurent [Equipe de Recherche en Signal et Imagerie Medicale, EA3295, Clermont-Ferrand (France)

    2005-07-01

    We report the performances of a 500 {mu}m pixellated silicon sensor bonded to the photon counting chip Medipix2 [1]. In order to perform an absolute characterization of our detector, we measured both the pre-sampling MTF and NPS with respect to the International standard IEC-62220-1. From those data we have been able to extract the Detective Quantum Efficiency (DQE) and hence to assess the suitability of our detector for X-ray medical imaging purpose. Due to poor absorption of the Si at 70 kV the DQE peaked at 0.06 for null frequency. Nevertheless, these results are very promising since thicker Si or more absorbing material such as GaAs will soon be available.

  9. Algorithm for Detection of Ground and Canopy Cover in Micropulse Photon-Counting Lidar Altimeter Data in Preparation for the ICESat-2 Mission

    Science.gov (United States)

    Herzfeld, Ute Christina; McDonald, Brian W.; Neumann, Thomas Allen; Wallin, Bruce F.; Neumann, Thomas A.; Markus, Thorsten; Brenner, Anita; Field, Christopher

    2014-01-01

    NASA's Ice, Cloud and Land Elevation Satellite-II (ICESat-2) mission is a decadal survey mission (2016 launch). The mission objectives are to measure land ice elevation, sea ice freeboard, and changes in these variables, as well as to collect measurements over vegetation to facilitate canopy height determination. Two innovative components will characterize the ICESat-2 lidar: 1) collection of elevation data by a multibeam system and 2) application of micropulse lidar (photon-counting) technology. A photon-counting altimeter yields clouds of discrete points, resulting from returns of individual photons, and hence new data analysis techniques are required for elevation determination and association of the returned points to reflectors of interest. The objective of this paper is to derive an algorithm that allows detection of ground under dense canopy and identification of ground and canopy levels in simulated ICESat-2 data, based on airborne observations with a Sigma Space micropulse lidar. The mathematical algorithm uses spatial statistical and discrete mathematical concepts, including radial basis functions, density measures, geometrical anisotropy, eigenvectors, and geostatistical classification parameters and hyperparameters. Validation shows that ground and canopy elevation, and hence canopy height, can be expected to be observable with high accuracy by ICESat-2 for all expected beam energies considered for instrument design (93.01%-99.57% correctly selected points for a beam with expected return of 0.93 mean signals per shot (msp), and 72.85%-98.68% for 0.48 msp). The algorithm derived here is generally applicable for elevation determination from photoncounting lidar altimeter data collected over forested areas, land ice, sea ice, and land surfaces, as well as for cloud detection.

  10. 时间相关单光子计数光谱仪的优化%Optimization of time-correlated single photon counting spectrometer

    Institute of Scientific and Technical Information of China (English)

    张秀峰; 杜海英; 孙进生

    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 in-troduced 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.%分析了原有时间相关单光子计数光谱仪存在的不足,提出了改进方案.研制了高速数据采集系统,采用PCI总线技术、FPGA技术,开发了高速光谱数据采集卡,取代了原有的多道分析仪,数据采集速度达到20MB/s,比原有仪器提高了约200倍;改善了仪器的性能、减小了体积.介绍了光谱仪系统的集成和工作流程,并对仪器的性能进行分析,通过多种标准样品的试验数据分析和对比,光谱仪系统具有最高的灵敏度-单光子计数,测得荧光寿命可达到ps量级,而且可以测得时间分辨光谱.

  11. Monte-Carlo simulation of a compact gamma-ray detector using wavelength-shifting fibers coupled to a YAP scintillation crystal

    Institute of Scientific and Technical Information of China (English)

    ZHU Jie; MA Hong-Guang; MA Wen-Yan; ZENG Hui; WANG Zhao-Min; XU Zi-Zong

    2008-01-01

    The production and transportation of fluorescent light produced in wavelength-shifting fibers (WSFs) coupled to YAP scintillation crystal is simulated using the GEANT4 codes.An advantage of the wavelength-shifting fiber readout technique over a direct readout with a position-sensitive photo-sensor is the reduced requirement for position sensitive photomultiplier tube photocathode area.With this gamma-ray detector,the gamma camera is small and flexible and has larger effective field of view and low cost.Simulation results show that a) a mean 12 of photons per 59.5 keV gamma ray interaction is produced in the WSF located nearest to the incident gamma ray,and a spatial resolution of 3.6 mm FWHM is obtained,b)a mean 27 of photons per 140 keV gamma ray interaction is produced and a spatial resolution of 3.1 mm FWHM is obtained.Results demonstrate the feasibility of this concept of a compact gamma-ray detector based on wavelength-shifting fibers readout.However,since the very low photoelectron levels,it is very important to use a photon counting device with good single photo-electron response to readout the WSFs.

  12. Accurate measurement of the rise and decay times of fast scintillators with solid state photon counters

    Science.gov (United States)

    Seifert, S.; Steenbergen, J. H. L.; van Dam, H. T.; Schaart, D. R.

    2012-09-01

    In this work we present a measurement setup for the determination of scintillation pulse shapes of fast scintillators. It is based on a time-correlated single photon counting approach that utilizes the correlation between 511 keV annihilation photons to produce start and stop signals in two separate crystals. The measurement is potentially cost-effective and simple to set up while maintaining an excellent system timing resolution of 125 ps. As a proof-of-concept the scintillation photon arrival time histograms were recorded for two well-known, fast scintillators: LYSO:Ce and LaBr3:5%Ce. The scintillation pulse shapes were modeled as a linear combination of exponentially distributed charge transfer and photon emission processes. Correcting for the system timing resolution, the exponential time constants were extracted from the recorded histograms. A decay time of 43 ns and a rise time of 72 ps were determined for LYSO:Ce thus demonstrating the capability of the system to accurately measure very fast rise times. In the case of LaBr3:5%Ce two processes were observed to contribute to the rising edge of the scintillation pulse. The faster component (270 ps) contributes with 72% to the rising edge of the scintillation pulse while the second, slower component (2.0 ns) contributes with 27%. The decay of the LaBr3:5%Ce scintillation pulse was measured to be 15.4 ns with a small contribution (2%) of a component with a larger time constant (130 ns).

  13. Scintillator materials for calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Weber, M.J. [Lawrence Berkeley Lab., CA (United States). Life Sciences Div.

    1994-09-01

    Requirements for fast, dense scintillator materials for calorimetry in high energy physics and approaches to satisfying these requirements are reviewed with respect to possible hosts and luminescent species. Special attention is given to cerium-activated crystals, core-valence luminescence, and glass scintillators. The present state of the art, limitations, and suggestions for possible new scintillator materials are presented.

  14. 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)

  15. 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...

  16. 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...

  17. Size-dependent scanning parameters (kVp and mAs) for photon-counting spectral CT system in pediatric imaging: simulation study.

    Science.gov (United States)

    Chen, Han; Danielsson, Mats; Xu, Cheng

    2016-06-07

    We are developing a photon-counting spectral CT detector with a small pixel size of [Formula: see text] mm(2), offering a potential advantage for better visualization of small structures in pediatric patients. The purpose of this study is to determine the patient size dependent scanning parameters (kVp and mAs) for pediatric CT in two imaging cases: adipose imaging and iodinated blood imaging. Cylindrical soft-tissue phantoms of diameters between 10-25 cm were used to mimic patients of different ages from 0 to 15 y. For adipose imaging, a 5 mm diameter adipose sphere was assumed as an imaging target, while in the case of iodinated imaging, an iodinated blood sphere of 1 mm in diameter was assumed. By applying the geometry of a commercial CT scanner (GE Lightspeed VCT), simulations were carried out to calculate the detectability index, [Formula: see text], with tube potentials varying from 40 to 140 kVp. The optimal kVp for each phantom in each imaging case was determined such that the dose-normalized detectability index, [Formula: see text]dose, is maximized. With the assumption that the detectability index in pediatric imaging is required the same as in typical adult imaging, the value of mAs at optimal kVp for each phantom was selected to achieve a reference detectability index that was obtained by scanning an adult phantom (30 cm in diameter) in a typical adult CT procedure (120 kVp and 200 mAs) using a modeled energy-integrating system. For adipose imaging, the optimal kVps are 50, 60, 80, and 120 kVp, respectively, for phantoms of 10, 15, 20, and 25 cm in diameter. The corresponding mAs values required to achieve the reference detectability index are only 9%, 23%, 24%, and 54% of the mAs that is used for adult patients at 120 kVp, for 10, 15, 20, and 25 cm diameter phantoms, respectively. In the case of iodinated imaging, a tube potential of 60 kVp was found optimal for all phantoms investigated, and the mAs values required to achieve the reference

  18. Size-dependent scanning parameters (kVp and mAs) for photon-counting spectral CT system in pediatric imaging: simulation study

    Science.gov (United States)

    Chen, Han; Danielsson, Mats; Xu, Cheng

    2016-06-01

    We are developing a photon-counting spectral CT detector with a small pixel size of 0.4× 0.5 mm2, offering a potential advantage for better visualization of small structures in pediatric patients. The purpose of this study is to determine the patient size dependent scanning parameters (kVp and mAs) for pediatric CT in two imaging cases: adipose imaging and iodinated blood imaging. Cylindrical soft-tissue phantoms of diameters between 10-25 cm were used to mimic patients of different ages from 0 to 15 y. For adipose imaging, a 5 mm diameter adipose sphere was assumed as an imaging target, while in the case of iodinated imaging, an iodinated blood sphere of 1 mm in diameter was assumed. By applying the geometry of a commercial CT scanner (GE Lightspeed VCT), simulations were carried out to calculate the detectability index, {{d}\\prime 2} , with tube potentials varying from 40 to 140 kVp. The optimal kVp for each phantom in each imaging case was determined such that the dose-normalized detectability index, {{d}\\prime 2}/ dose, is maximized. With the assumption that the detectability index in pediatric imaging is required the same as in typical adult imaging, the value of mAs at optimal kVp for each phantom was selected to achieve a reference detectability index that was obtained by scanning an adult phantom (30 cm in diameter) in a typical adult CT procedure (120 kVp and 200 mAs) using a modeled energy-integrating system. For adipose imaging, the optimal kVps are 50, 60, 80, and 120 kVp, respectively, for phantoms of 10, 15, 20, and 25 cm in diameter. The corresponding mAs values required to achieve the reference detectability index are only 9%, 23%, 24%, and 54% of the mAs that is used for adult patients at 120 kVp, for 10, 15, 20, and 25 cm diameter phantoms, respectively. In the case of iodinated imaging, a tube potential of 60 kVp was found optimal for all phantoms investigated, and the mAs values required to achieve the reference detectability

  19. An Algorithm for Detection of Ground and Canopy Cover in Micropulse Photon-Counting Lidar Altimeter Data in Preparation of the ICESat-2 Mission

    Science.gov (United States)

    Herzfeld, Ute C.; McDonald, Brian W.; Wallins, Bruce F.; Markus, Thorsten; Neumann, Thomas A.; Brenner, Anita

    2012-01-01

    The Ice, Cloud and Land Elevation Satellite-II (ICESat-2) mission has been selected by NASA as a Decadal Survey mission, to be launched in 2016. Mission objectives are to measure land ice elevation, sea ice freeboard/ thickness and changes in these variables and to collect measurements over vegetation that will facilitate determination of canopy height, with an accuracy that will allow prediction of future environmental changes and estimation of sea-level rise. The importance of the ICESat-2 project in estimation of biomass and carbon levels has increased substantially, following the recent cancellation of all other planned NASA missions with vegetation-surveying lidars. Two innovative components will characterize the ICESat-2 lidar: (1) Collection of elevation data by a multi-beam system and (2) application of micropulse lidar (photon counting) technology. A micropulse photon-counting altimeter yields clouds of discrete points, which result from returns of individual photons, and hence new data analysis techniques are required for elevation determination and association of returned points to reflectors of interest including canopy and ground in forested areas. The objective of this paper is to derive and validate an algorithm that allows detection of ground under dense canopy and identification of ground and canopy levels in simulated ICESat-2-type data. Data are based on airborne observations with a Sigma Space micropulse lidar and vary with respect to signal strength, noise levels, photon sampling options and other properties. A mathematical algorithm is developed, using spatial statistical and discrete mathematical concepts, including radial basis functions, density measures, geometrical anisotropy, eigenvectors and geostatistical classification parameters and hyperparameters. Validation shows that the algorithm works very well and that ground and canopy elevation, and hence canopy height, can be expected to be observable with a high accuracy during the ICESat

  20. 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

  1. Direct observation of avalanche scintillations in a THGEM-based two-phase Ar avalanche detector using Geiger-mode APD

    CERN Document Server

    Bondar, A; Grebenuk, A; Sokolov, A; Akimov, D; Alexandrov, I; Breskin, A

    2010-01-01

    A novel concept of optical signal recording in two-phase avalanche detectors, with Geiger-mode Avalanche Photodiodes (G-APD) is described. Avalanche-scintillation photons were measured in a thick Gas Electron Multiplier (THGEM) in view of potential applications in rare-event experiments. The effective detection of avalanche scintillations in THGEM holes has been demonstrated in two-phase Ar with a bare G-APD without wavelength shifter, i.e. insensitive to VUV emission of Ar. At gas-avalanche gain of 400 and under \\pm 70^\\circ viewing-angle, the G-APD yielded 640 photoelectrons (pe) per 60 keV X-ray converted in liquid Ar; this corresponds to 0.7 pe per initial (prior to multiplication) electron. The avalanche-scintillation light yield measured by the G-APD was about 0.7 pe per avalanche electron, extrapolated to 4pi acceptance. The avalanche scintillations observed occurred presumably in the near infrared (NIR) where G-APDs may have high sensitivity. The measured scintillation yield is similar to that observe...

  2. Characterization of the scintillation anisotropy in crystalline stilbene scintillator detectors

    CERN Document Server

    Schuster, Patricia

    2016-01-01

    This paper reports a series of measurements that characterize the directional dependence of the scintillation response of crystalline melt-grown and solution-grown stilbene to incident DT and DD neutrons. These measurements give the amplitude and pulse shape dependence on the proton recoil direction over one hemisphere of the crystal, confirming and extending previous results in the literature for melt-grown stilbene and providing the first measurements for solution-grown stilbene. In similar measurements of liquid and plastic detectors, no directional dependence was observed, confirming the hypothesis that the anisotropy in stilbene and other organic crystal scintillators is a result of internal effects due to the molecular or crystal structure and not an external effect on the measurement system.

  3. 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.

  4. Time-resolved non-contact fluorescence diffuse optical tomography measurements with ultra-fast time-correlated single photon counting avalanche photodiodes

    Science.gov (United States)

    Bérubé-Lauzière, Yves; Robichaud, Vincent; Lapointe, Éric

    2007-07-01

    The design and fabrication of time-correlated single photon counting (TCSPC) avalanche photodiodes (APDs) and associated quenching circuits have made significant progresses in recent years. APDs with temporal resolutions comparable to microchannel plate photomultiplier tubes (MCP-PMTs) are now available. MCP-PMTs were until these progresses the best TCSPC detectors with timing resolutions down to 30ps. APDs can now achieve these resolutions at a fraction of the cost. Work is under way to make the manufacturing of TCSPC APDs compatible with standard electronics fabrication practices. This should allow to further reduce their cost and render them easier to integrate in complex multi-channel TCSPC electronics, as needed in diffuse optical tomography (DOT) systems. Even if their sensitive area is much smaller than that of the ubiquitous PMT used in TCSPC, we show that with appropriate selection of optical components, TCSPC APDs can be used in time-domain DOT. To support this, we present experimental data and calculations clearly demonstrating that comparable measurements can be obtained with APDs and PMTs. We are, to our knowledge, the first group using APDs in TD DOT, in particular in non-contact TD fluorescence DOT.

  5. Cross strip anode readouts for large format, photon counting microchannel plate detectors: developing flight qualified prototypes of the detector and electronics

    Science.gov (United States)

    Vallerga, John; Raffanti, Rick; Cooney, Michael; Cumming, Harley; Varner, Gary; Seljak, Andrej

    2014-07-01

    Photon counting microchannel plate (MCP) imagers have been the detector of choice for most UV astronomical missions over the last two decades (e.g. EUVE, FUSE, COS on Hubble etc.). Over this duration, improvements in the MCP laboratory readout technology have resulted in better spatial resolution (x10), temporal resolution (x1000) and output event rate (x100), all the while operating at lower gain (x 10) resulting in lower high voltage requirements and longer MCP lifetimes. One such technology is the parallel cross strip (PXS) readout. Laboratory versions of PXS electronics have demonstrated count rates on the order of 2 MHz, and temporal resolution of ~ 1ns. In 2012 our group at U.C. Berkeley, along with our partners at the U. Hawaii, received a Strategic Astrophysics Technology grant to raise the TRL of the PXS detector and electronics from 4 to 6 by replacing most of the high powered electronics with application specific integrated circuits (ASICs) which will lower the power, mass and volume requirements of the PXS detector. We were also tasked to design and fabricate a "standard" 50mm square active area MCP detector incorporating these electronics that can be environmentally qualified for flight (temperature, vacuum, vibration). The first ASICs designed for this program have been fabricated and are undergoing testing. We present the latest progress on these ASIC designs and performance and show imaging results from the new 50 x 50 mm XS detector.

  6. Estimation of basis line-integrals in a spectral distortion-modeled photon counting detector using low-order polynomial approximation of x-ray transmittance.

    Science.gov (United States)

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

    2016-10-26

    Photon counting detector (PCD)-based computed tomography exploits spectral information from a transmitted x-ray spectrum to estimate basis line-integrals. The recorded spectrum, however, is distorted and deviates from the transmitted spectrum due to spectral response effect (SRE). Therefore, the SRE needs to be compensated for when estimating basis lineintegrals. One approach is to incorporate the SRE model with an incident spectrum into the PCD measurement model and the other approach is to perform a calibration process that inherently includes both the SRE and the incident spectrum. A maximum likelihood estimator can be used to the former approach, which guarantees asymptotic optimality; however, a heavy computational burden is a concern. Calibration-based estimators are a form of the latter approach. They can be very efficient; however, a heuristic calibration process needs to be addressed. In this paper, we propose a computationally efficient three-step estimator for the former approach using a low-order polynomial approximation of x-ray transmittance. The low-order polynomial approximation can change the original non-linear estimation method to a two-step linearized approach followed by an iterative bias correction step. We show that the calibration process is required only for the bias correction step and prove that it converges to the unbiased solution under practical assumptions. Extensive simulation studies validate the proposed method and show that the estimation results are comparable to those of the ML estimator while the computational time is reduced substantially.

  7. A Ring Artifact Correction Method: Validation by Micro-CT Imaging with Flat-Panel Detectors and a 2D Photon-Counting Detector

    Directory of Open Access Journals (Sweden)

    Mohamed Elsayed Eldib

    2017-01-01

    Full Text Available We introduce an efficient ring artifact correction method for a cone-beam computed tomography (CT. In the first step, we correct the defective pixels whose values are close to zero or saturated in the projection domain. In the second step, we compute the mean value at each detector element along the view angle in the sinogram to obtain the one-dimensional (1D mean vector, and we then compute the 1D correction vector by taking inverse of the mean vector. We multiply the correction vector with the sinogram row by row over all view angles. In the third step, we apply a Gaussian filter on the difference image between the original CT image and the corrected CT image obtained in the previous step. The filtered difference image is added to the corrected CT image to compensate the possible contrast anomaly that may appear due to the contrast change in the sinogram after removing stripe artifacts. We applied the proposed method to the projection data acquired by two flat-panel detectors (FPDs and a silicon-based photon-counting X-ray detector (PCXD. Micro-CT imaging experiments of phantoms and a small animal have shown that the proposed method can greatly reduce ring artifacts regardless of detector types. Despite the great reduction of ring artifacts, the proposed method does not compromise the original spatial resolution and contrast.

  8. Weighted singular value decomposition (wSVD) to improve the radiation dose efficiency of grating-based x-ray phase contrast imaging with a photon counting detector

    Science.gov (United States)

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

    2017-03-01

    The noise performance of grating-based differential phase contrast (DPC) imaging system is strongly dependent on the fringe visibility of the grating interferometer. Since the grating interferometer system is usually designed to be operated at a specific energy, deviation from that energy may lead to visibility loss and increased noise. By incorporating an energy-discriminating photon counting detector (PCD) into the system, photons with energies close to the operation energy of the interferometer can be selected, which offers the possibility of contrast-tonoise ratio (CNR) improvement. In our previous work, a singular value decomposition (SVD)-based rank one approximation method was developed to improve the CNR of DPC imaging. However, as the noise level and energy sensitivity of the interferometer may vary significantly from one energy bin to another, the signal and noise may not be separated well using the previously proposed method, therefore the full potential of the SVD method may not be achieved. This work presents a weighted SVD-based method, which maintains the noise reduction capability regardless of the similarity in the noise level across energy bins. The optimal weighting scheme was theoretically derived, and experimental phantom studies were performed to validate the theory and demonstrate the improved radiation dose efficiency of the proposed weighted SVD method.

  9. CLARO-CMOS: a fast, low power and radiation-hard front-end ASIC for single-photon counting in 0.35 micron CMOS technology

    Science.gov (United States)

    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 designed for fast photon counting with multi-anode photomultiplier tubes (MaPMT). The CLARO features a 5 ns peaking time, a recovery time to baseline smaller than 25 ns, and a power consumption of less than 1 mW per channel. The chip was designed in 0.35 μm CMOS technology, and was tested for radiation hardness with neutrons up to 1014 1 MeV neq/cm2, X-rays up to 40 kGy and protons up to 76 kGy. Its capability to read out single photons at high rate from a Hamamatsu R11265 MaPMT, the baseline photon detector for the LHCb RICH upgrade, was demonstrated both with test bench measurements and with actual signals from a R11265 MaPMT. The presented results allowed CLARO to be chosen as the front-end readout chip in the upgraded LHCb RICH detector.

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

    Science.gov (United States)

    Amendolia, S R; Bisogni, M G; Delogu, P; Fantacci, M E; Paternoster, G; Rosso, V; Stefanini, A

    2009-04-01

    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.

  11. 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.

  12. Development of Photon-Counting Laser-Light- Scattering Method for Size- and Density-Measurements of Nano-Particles Forme d in Processing Plasmas

    Science.gov (United States)

    Maeda, S.; Sakamoto, K.; Fukuzawa, T.; Shiratani, M.; Watanabe, Y.

    1998-10-01

    A high sensitive photon-counting laser-light-scattering (PCLLS) method for detection of nano-particles formed in processing plasmas is developed to get information on nucleation and subsequent initial growth of particles. Two different methods are employed to deduce particle-size and -density from time evolution of LLS intensity after turning off the discharge. In one method, size of particles is deduced from their diffusion after turning off the discharge and their density is obtained using the size and absolute LLS intensity.^1. In the other method, density of particles is deduced from their coagulation after turning off the discharge and their size is obtained using the density and absolute LLS intensity. Results obtained by both the methods agree fairly well with each other. Using the developed method, we demonstrate detection of small particles down to a few nm in size and find the corresponding particle density is above 10^10 cm-3 even in low pressure silane rf discharges of low rf power, which are commonly used to deposit high quality a-Si:H films^1M. Shiratani and Y. Watanabe, Rev. Laser Eng. Vol. 26, No. 6 (1998) in press.

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

    Science.gov (United States)

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

    2017-03-01

    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.

  14. A Ring Artifact Correction Method: Validation by Micro-CT Imaging with Flat-Panel Detectors and a 2D Photon-Counting Detector

    Science.gov (United States)

    Eldib, Mohamed Elsayed; Hegazy, Mohamed; Mun, Yang Ji; Cho, Myung Hye; Cho, Min Hyoung; Lee, Soo Yeol

    2017-01-01

    We introduce an efficient ring artifact correction method for a cone-beam computed tomography (CT). In the first step, we correct the defective pixels whose values are close to zero or saturated in the projection domain. In the second step, we compute the mean value at each detector element along the view angle in the sinogram to obtain the one-dimensional (1D) mean vector, and we then compute the 1D correction vector by taking inverse of the mean vector. We multiply the correction vector with the sinogram row by row over all view angles. In the third step, we apply a Gaussian filter on the difference image between the original CT image and the corrected CT image obtained in the previous step. The filtered difference image is added to the corrected CT image to compensate the possible contrast anomaly that may appear due to the contrast change in the sinogram after removing stripe artifacts. We applied the proposed method to the projection data acquired by two flat-panel detectors (FPDs) and a silicon-based photon-counting X-ray detector (PCXD). Micro-CT imaging experiments of phantoms and a small animal have shown that the proposed method can greatly reduce ring artifacts regardless of detector types. Despite the great reduction of ring artifacts, the proposed method does not compromise the original spatial resolution and contrast. PMID:28146088

  15. A New Columnar CsI(Tl) Scintillator for iQID detectors.

    Science.gov (United States)

    Han, Ling; Miller, Brian W; Barber, H Bradford; Nagarkar, Vivek V; Furenlid, Lars R

    2014-09-12

    A 1650 μm thick columnar CsI(Tl) scintillator for upgrading iQID detectors, which is a high-resolution photon-counting gamma-ray and x-ray detector recently developed at the Center for Gamma-Ray Imaging (CGRI), has been studied in terms of sensitivity, spatial resolution and depth-of-interaction effects. To facilitate these studies, a new frame-parsing algorithm for processing raw event data is also proposed that has more degrees of freedom in data processing and can discriminate against a special kind of noise present in some low-cost intensifiers. The results show that in comparison with a 450 μm-thickness columnar CsI(Tl) scintillator, the 1650 μm thick CsI(Tl) scintillator provides more than twice the sensitivity at the expense of some spatial resolution degradation. The depth-of-interaction study also shows that event size and amplitude vary with scintillator thickness, which can assist in future detector simulations and 3D-interaction-position estimation.

  16. Subnanosecond Scintillation Detector

    Science.gov (United States)

    Hoenk, Michael (Inventor); Hennessy, John (Inventor); Hitlin, David (Inventor)

    2017-01-01

    A scintillation detector, including a scintillator that emits scintillation; a semiconductor photodetector having a surface area for receiving the scintillation, wherein the surface area has a passivation layer configured to provide a peak quantum efficiency greater than 40% for a first component of the scintillation, and the semiconductor photodetector has built in gain through avalanche multiplication; a coating on the surface area, wherein the coating acts as a bandpass filter that transmits light within a range of wavelengths corresponding to the first component of the scintillation and suppresses transmission of light with wavelengths outside said range of wavelengths; and wherein the surface area, the passivation layer, and the coating are controlled to increase the temporal resolution of the semiconductor photodetector.

  17. Digital signal processing for a thermal neutron detector using ZnS(Ag):6LiF scintillating layers read out with WLS fibers and SiPMs

    OpenAIRE

    Mosset, J. -B.; Stoykov, A.; Greuter, U.; Hildebrandt, M.; Schlumpf, N.

    2015-01-01

    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):6LiF 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^4 filter. The performances of the detector with these filters are presented. A full analog signal processing using a CR-RC^4 filter has been emulated digitally. The dete...

  18. Digital signal processing for a thermal neutron detector using ZnS(Ag):6LiF scintillating layers read out with WLS fibers and SiPMs

    Science.gov (United States)

    Mosset, J.-B.; Stoykov, A.; Greuter, U.; Hildebrandt, M.; Schlumpf, N.

    2016-07-01

    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):6LiF 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-RC4 filter. The performances of the detector with these filters are presented. A full analog signal processing using a CR-RC4 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.

  19. Digital signal processing for a thermal neutron detector using ZnS(Ag):6LiF scintillating layers read out with WLS fibers and SiPMs

    CERN Document Server

    Mosset, J -B; Greuter, U; Hildebrandt, M; Schlumpf, N

    2015-01-01

    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):6LiF 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^4 filter. The performances of the detector with these filters are presented. A full analog signal processing using a CR-RC^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.

  20. A cascaded model of spectral distortions due to spectral response effects and pulse pileup effects in a photon-counting x-ray detector for CT

    Energy Technology Data Exchange (ETDEWEB)

    Cammin, Jochen, E-mail: jcammin1@jhmi.edu, E-mail: ktaguchi@jhmi.edu; Taguchi, Katsuyuki, E-mail: jcammin1@jhmi.edu, E-mail: ktaguchi@jhmi.edu [Division of Medical Imaging Physics, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287 (United States); Xu, Jennifer [Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland 21287 (United States); Barber, William C.; Iwanczyk, Jan S.; Hartsough, Neal E. [DxRay, Inc., Northridge, California 91324 (United States)

    2014-04-15

    Purpose: Energy discriminating, photon-counting detectors (PCDs) are an emerging technology for computed tomography (CT) with various potential benefits for clinical CT. The photon energies measured by PCDs can be distorted due to the interactions of a photon with the detector and the interaction of multiple coincident photons. These effects result in distorted recorded x-ray spectra which may lead to artifacts in reconstructed CT images and inaccuracies in tissue identification. Model-based compensation techniques have the potential to account for the distortion effects. This approach requires only a small number of parameters and is applicable to a wide range of spectra and count rates, but it needs an accurate model of the spectral distortions occurring in PCDs. The purpose of this study was to develop a model of those spectral distortions and to evaluate the model using a PCD (model DXMCT-1; DxRay, Inc., Northridge, CA) and various x-ray spectra in a wide range of count rates. Methods: The authors hypothesize that the complex phenomena of spectral distortions can be modeled by: (1) separating them into count-rate independent factors that we call the spectral response effects (SRE), and count-rate dependent factors that we call the pulse pileup effects (PPE), (2) developing separate models for SRE and PPE, and (3) cascading the SRE and PPE models into a combined SRE+PPE model that describes PCD distortions at both low and high count rates. The SRE model describes the probability distribution of the recorded spectrum, with a photo peak and a continuum tail, given the incident photon energy. Model parameters were obtained from calibration measurements with three radioisotopes and then interpolated linearly for other energies. The PPE model used was developed in the authors’ previous work [K. Taguchi et al., “Modeling the performance of a photon counting x-ray detector for CT: Energy response and pulse pileup effects,” Med. Phys. 38(2), 1089–1102 (2011

  1. Fast photon counting imaging system based on MCP%基于MCP的快速光子计数成像系统的设计方案

    Institute of Scientific and Technical Information of China (English)

    李梅

    2012-01-01

    通常基于MCP的阳极探测系统获得图像的速度受到噪声和信号处理速度的限制,影响了图像的时间分辨率和空间分辨率.介绍了一种快速光子计数成像探测器,使用的阳极结构避免了需要高信噪比的信号测量电路,及模拟信号到数字信号的转换,缩短了电子信号处理的时间,能有效提高图像质量.阳极面板依据格雷码编码方式划分区域,因此从微通道板出来的电子云在位敏阳极上的质心位星,由成对电极上的电荷比较值来确定,省略了由模拟信号变为数字信号的过程.所以对比较器的要求较高,要有高的运算速度,前端电子学具有高速、低噪、线性的特性.在此对快速先子计数成像系统提出了整体设计方案,并得到初步的实验结果,证实方案可行.%The image acquisition speed of positive pole detection system with MCP is usually limited by noise and signal processing speed, which reduce the time resolution and space resolution. A fast photon counting imaging system is introduced in this paper. The anode structure used in the detector avoids the demand of the signal detection circuit which requires high signal to noise ratio and analogue to digital conversion, curtails the time of signal processing* and improves the image quality effectively. The anode panel is divided according to the coding mode of Gray code, so the centroid position of electronic cloud on the position sensitive anode, coming form MCP, is determined by charge comparing values on pairs of electrodes. It omits the converting process of analogue signal to digital signal. Therefore, it requires very high-speed comparators. The front-end electronics has the characteristics of high-speed, low-noise and linear response. A design scheme of the fast photon counting imaging system is put forward in the article. The preliminary experiment results have been achieved. It confirms that the scheme is feasible.

  2. Detective quantum efficiency for photon-counting hybrid pixel detectors in the tender X-ray domain: application to Medipix3RX.

    Science.gov (United States)

    Rinkel, Jean; Magalhães, Debora; Wagner, Franz; Meneau, Florian; Cesar Vicentin, Flavio

    2016-01-01

    Synchrotron-radiation-based X-ray imaging techniques using tender X-rays are facing a growing demand, in particular to probe the K absorption edges of low-Z elements. Here, a mathematical model has been developed for estimating the detective quantum efficiency (DQE) at zero spatial frequency in the tender X-ray energy range for photon-counting detectors by taking into account the influence of electronic noise. The experiments were carried out with a Medipix3RX ASIC bump-bonded to a 300 µm silicon sensor at the Soft X-ray Spectroscopy beamline (D04A-SXS) of the Brazilian Synchrotron Light Laboratory (LNLS, Campinas, Brazil). The results show that Medipix3RX can be used to develop new imaging modalities in the tender X-ray range for energies down to 2 keV. The efficiency and optimal DQE depend on the energy and flux of the photons. The optimal DQE values were found in the 7.9-8.6 keV photon energy range. The DQE deterioration for higher energies due to the lower absorption efficiency of the sensor and for lower energies due to the electronic noise has been quantified. The DQE for 3 keV photons and 1 × 10(4) photons pixel(-1) s(-1) is similar to that obtained with 19 keV photons. Based on our model, the use of Medipix3RX could be extended down to 2 keV which is crucial for coming applications in imaging techniques at modern synchrotron sources.

  3. Imaging performance of phase-contrast breast computed tomography with synchrotron radiation and a CdTe photon-counting detector.

    Science.gov (United States)

    Sarno, A; Mettivier, G; Golosio, B; Oliva, P; Spandre, G; Di Lillo, F; Fedon, C; Longo, R; Russo, P

    2016-05-01

    Within the SYRMA-CT collaboration based at the ELETTRA synchrotron radiation (SR) facility the authors investigated the imaging performance of the phase-contrast computed tomography (CT) system dedicated to monochromatic in vivo 3D imaging of the female breast, for breast cancer diagnosis. Test objects were imaged at 38keV using monochromatic SR and a high-resolution CdTe photon-counting detector. Signal and noise performance were evaluated using modulation transfer function (MTF) and noise power spectrum. The analysis was performed on the images obtained with the application of a phase retrieval algorithm as well as on those obtained without phase retrieval. The contrast to noise ratio (CNR) and the capability of detecting test microcalcification clusters and soft masses were investigated. For a voxel size of (60μm)(3), images without phase retrieval showed higher spatial resolution (6.7mm(-1) at 10% MTF) than corresponding images with phase retrieval (2.5mm(-1)). Phase retrieval produced a reduction of the noise level and an increase of the CNR by more than one order of magnitude, compared to raw phase-contrast images. Microcalcifications with a diameter down to 130μm could be detected in both types of images. The investigation on test objects indicates that breast CT with a monochromatic SR source is technically feasible in terms of spatial resolution, image noise and contrast, for in vivo 3D imaging with a dose comparable to that of two-view mammography. Images obtained with the phase retrieval algorithm showed the best performance in the trade-off between spatial resolution and image noise. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  4. A feasibility study of projection-based energy weighting based on a photon-counting detector in contrast-enhanced digital subtraction mammography: A simulation study

    Science.gov (United States)

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

    2014-06-01

    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.

  5. Nonproportionality of inorganic scintillators

    NARCIS (Netherlands)

    Khodyuk, I.V.

    2013-01-01

    A scintillator is a transparent material that emits a flash of light when it absorbs a γ-ray photon or an energetic particle. Scintillation crystals are widely used as spectroscopic detectors of ionizing radiation in nuclear science, space exploration, medical imaging, homeland security, etc. This t

  6. Anticoincidence scintillation counter

    CERN Multimedia

    1966-01-01

    This anticoincidence scintillation counter will be mounted in a hydrogen target vessel to be used in a measurement of the .beta. parameter in the .LAMBDA0. decay. The geometry of the counter optimizes light collection in the central part where a scintillation disk of variable thickness can be fitted.

  7. 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)

  8. A helical scintillating fiber hodoscope

    Energy Technology Data Exchange (ETDEWEB)

    Altmeier, M.; Bauer, F.; Bisplinghoff, J.; Bissel, T.; Bollmann, R.; Busch, M.; Buesser, 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.; Rossen, P. von; 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

    1999-07-21

    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)

  9. 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

  10. Time and position sensitive single photon detector for scintillator read-out

    Science.gov (United States)

    Schössler, S.; Bromberger, B.; Brandis, M.; Schmidt, L. Ph H.; Tittelmeier, K.; Czasch, A.; Dangendorf, V.; Jagutzki, O.

    2012-02-01

    We have developed a photon counting detector system for combined neutron and γ radiography which can determine position, time and intensity of a secondary photon flash created by a high-energy particle or photon within a scintillator screen. The system is based on a micro-channel plate photomultiplier concept utilizing image charge coupling to a position- and time-sensitive read-out anode placed outside the vacuum tube in air, aided by a standard photomultiplier and very fast pulse-height analyzing electronics. Due to the low dead time of all system components it can cope with the high throughput demands of a proposed combined fast neutron and dual discrete energy γ radiography method (FNDDER). We show tests with different types of delay-line read-out anodes and present a novel pulse-height-to-time converter circuit with its potential to discriminate γ energies for the projected FNDDER devices for an automated cargo container inspection system (ACCIS).

  11. Time and position sensitive single photon detector for scintillator read-out

    CERN Document Server

    Schössler, Sven; Brandis, Michal; Schmidt, Lothar Ph H; Tittelmeier, Kai; Czasch, Achim; Dangendorf, Volker; Jagutzki, Ottmar

    2012-01-01

    We have developed a photon counting detector system for combined neutron and gamma radiography which can determine position, time and intensity of a secondary photon flash created by a high-energy particle or photon within a scintillator screen. The system is based on a micro-channel plate photomultiplier concept utilizing image charge coupling to a position- and time-sensitive read-out anode placed outside the vacuum tube in air, aided by a standard photomultiplier and very fast pulse-height analyzing electronics. Due to the low dead time of all system components it can cope with the high throughput demands of a proposed combined fast neutron and dual discrete energy gamma radiography method (FNDDER). We show tests with different types of delay-line read-out anodes and present a novel pulse-height-to-time converter circuit with its potential to discriminate gamma energies for the projected FNDDER devices for an automated cargo container inspection system (ACCIS).

  12. Measurements of proportional scintillation in liquid xenon using thin wires

    CERN Document Server

    Aprile, E; Goetzke, L W; Fernandez, A J Melgarejo; Messina, M; Naganoma, J; Plante, G; Rizzo, A; Shagin, P; Wall, R

    2014-01-01

    Proportional scintillation in liquid xenon has a promising application in the field of direct dark matter detection, potentially allowing for simpler, more sensitive detectors. However, knowledge of the basic properties of the phenomenon as well as guidelines for its practical use are currently limited. We report here on measurements of proportional scintillation light emitted in liquid xenon around thin wires. The maximum proportional scintillation gain of $287^{+97}_{-75}$ photons per drift electron was obtained using 10 $\\mu$m diameter gold plated tungsten wire. The thresholds for electron multiplication and proportional scintillation are measured as $725^{+48}_{-139}$ and $412^{+10}_{-133}$ kV/cm, respectively. The threshold for proportional scintillation is in good agreement with a previously published result, while the electron multiplication threshold represents a novel measurement. A complete set of parameters for the practical use of the electron multiplication and proportional scintillation processe...

  13. Properties of Quantum-Dot-Doped Liquid Scintillators

    Science.gov (United States)

    Coy, Christopher

    2014-03-01

    Novel scintillators based on semiconducting nanocrystals called quantum dots have unique optical and chemical properties that make them interesting for future neutrino experiments especially those searching for neutrino-less double beta decay. In this talk, we report the results of laboratory-scale measurements for three candidate quantum-dot-doped scintillators. We focus on the key properties required for large-scale neutrino experiments, which are the emission spectrum, the attenuation length and the stability. I would like to follow the talk by Andrey Elagin on directionality in scintillators and precede Athena Ierokomos' talk on light yield in scintillators.

  14. A Monte Carlo simulation study of an improved K-edge log-subtraction X-ray imaging using a photon counting CdTe detector

    Science.gov (United States)

    Lee, Youngjin; Lee, Amy Candy; Kim, Hee-Joung

    2016-09-01

    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

  15. Photon-counting imaging system based on compressive sensing%基于压缩传感的光子计数成像系统

    Institute of Scientific and Technical Information of China (English)

    杜克铭; 蒋远大; 陈颖; 王迪; 王超; 孙志斌; 翟光杰

    2012-01-01

    Based on compressive sensing, a new photon-counting imaging system was proposed. Using single-photon counter as the detector, this point-type detector was used to detect ultralow light and obtain the two-dimensional image while the plane-type detector was not very developed. By performing simulation on the computer, the feasibility of the system was verified. The effects of the single-photon counter' s dark count rate, quantum efficiency and measurement noise on the quality of the obtained image were discussed. And compressive sensing theory was introduced. In order to obtain a better image and faster computing speed, a new image reconstruction algorithm, SpaRSA-DWT, was proposed. The experiment results show that SpaRSA-DWT needs less measurement and iteration times compared with the typical IWT algorithm, and is more robust to noise.%提出了一种基于压缩传感理论的光子计数成像系统.该系统以单光子计数器作为探测元件,以期在面元探测技术不甚成熟的现状下用点探测器进行极弱光探测.通过计算机模拟计算,验证了压缩传感理论结合单光子计数器应用于极弱光成像的可行性,讨论了单光子计数器的暗计数率、量子效率和测量噪声对成像质量的影响.介绍了压缩传感理论,为了获得更好的图像质量和更快的计算速度,提出了SpaRSA-DWT稀疏重建算法,并与传统的IWT算法进行对比.给出了两种算法下,迭代次数、测量数、噪声功率分别与获得图像信噪比的关系曲线,证明了SpaRSA-DWT算法的优越性.

  16. A high-resolution photon-counting breast CT system with tensor-framelet based iterative image reconstruction for radiation dose reduction

    Science.gov (United States)

    Ding, Huanjun; Gao, Hao; Zhao, Bo; Cho, Hyo-Min; Molloi, Sabee

    2014-10-01

    Both computer simulations and experimental phantom studies were carried out to investigate the radiation dose reduction with tensor framelet based iterative image reconstruction (TFIR) for a dedicated high-resolution spectral breast computed tomography (CT) based on a silicon strip photon-counting detector. The simulation was performed with a 10 cm-diameter water phantom including three contrast materials (polyethylene, 8 mg ml-1 iodine and B-100 bone-equivalent plastic). In the experimental study, the data were acquired with a 1.3 cm-diameter polymethylmethacrylate (PMMA) phantom containing iodine in three concentrations (8, 16 and 32 mg ml-1) at various radiation doses (1.2, 2.4 and 3.6 mGy) and then CT images were reconstructed using the filtered-back-projection (FBP) technique and the TFIR technique, respectively. The image quality between these two techniques was evaluated by the quantitative analysis on contrast-to-noise ratio (CNR) and spatial resolution that was evaluated using the task-based modulation transfer function (MTF). Both the simulation and experimental results indicated that the task-based MTF obtained from TFIR reconstruction with one-third of the radiation dose was comparable to that from the FBP reconstruction for low contrast target. For high contrast target, the TFIR was substantially superior to the FBP reconstruction in terms of spatial resolution. In addition, TFIR was able to achieve a factor of 1.6-1.8 increase in CNR, depending on the target contrast level. This study demonstrates that the TFIR can reduce the required radiation dose by a factor of two-thirds for a CT image reconstruction compared to the FBP technique. It achieves much better CNR and spatial resolution for high contrast target in addition to retaining similar spatial resolution for low contrast target. This TFIR technique has been implemented with a graphic processing unit system and it takes approximately 10 s to reconstruct a single-slice CT image

  17. 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

  18. SR study of scintillators

    CERN Document Server

    Mikhailin, V V

    2000-01-01

    The technique and the models developed recently in Synchrotron Radiation (SR) Laboratory of Moscow University for the investigation of energy transfer processes in insulators can be applied for a detailed study of scintillator's properties. The experiments with SR in VUV and XUV regions allow to separate various processes and stages of energy transfer and help to indicate the dominating process on each stage. Thus, we can find the way to improve the properties, essential for the particular application of the scintillator: conversion efficiency, decay time, afterglow, radiation hardness, etc. The results of such a study can be used for the testing procedures in scintillator production.

  19. Scintillation Monitoring Using Asymmetry Index

    Science.gov (United States)

    Shaikh, Muhammad Mubasshir; Mahrous, Ayman; Abdallah, Amr; Notarpietro, Riccardo

    Variation in electron density can have significant effect on GNSS signals in terms of propagation delay. Ionospheric scintillation can be caused by rapid change of such delay, specifically, when they last for a longer period of time. Ionospheric irregularities that account for scintillation may vary significantly in spatial range and drift with the background plasma at speeds of 45 to 130 m/sec. These patchy irregularities may occur several times during night, e.g. in equatorial region, with the patches move through the ray paths of the GNSS satellite signals. These irregularities are often characterized as either ‘large scale’ (which can be as large as several hundred km in East-West direction and many times that in the North-South direction) or ‘small scale’ (which can be as small as 1m). These small scale irregularities are regarded as the main cause of scintillation [1,2]. In normal solar activity conditions, the mid-latitude ionosphere is not much disturbed. However, during severe magnetic storms, the aurora oval extends towards the equator and the equator anomaly region may stretched towards poles extending the scintillation phenomena more typically associated with those regions into mid-latitudes. In such stormy conditions, the predicted TEC may deviate largely from the true value of the TEC both at low and mid-latitudes due to which GNSS applications may be strongly degraded. This work is an attempt to analyze ionospheric scintillation (S4 index) using ionospheric asymmetry index [3]. The asymmetry index is based on trans-ionospheric propagation between GPS and LEO satellites in a radio occultation (RO) scenario, using background ionospheric data provided by MIDAS [4]. We attempted to simulate one of the recent geomagnetic storms (NOAA scale G4) occurred over low/mid-latitudes. The storm started on 26 September 2011 at UT 18:00 and lasted until early hours of 27 September 2011. The scintillation data for the storm was taken from an ionospheric

  20. 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...

  1. Properties and applications of photon counting and energy resolved X-ray matrix detectors; Eigenschaften und Einsatzgebiete photonenzaehlender und energieaufloesender Roentgenmatrixdetektoren

    Energy Technology Data Exchange (ETDEWEB)

    Walter, David; Zscherpel, Uwe; Ewert, Uwe [BAM Bundesanstalt fuer Materialforschung und -pruefung, Berlin (Germany); Ullberg, Christer; Weber, Niclas; Urech, Mattias [XCounter AB, Danderyd (Sweden); Pantsar, Tuomas; Perez-Fuster, Katya [Ajat Oy Ltd., Espoo (Finland)

    2015-07-01

    The use of highly absorbing photoconductor materials (e.g. CdTe) for the production of matrix X-ray detectors allows for a number of years, the direct conversion of X-rays into evaluable electrical signals, for the NDT energy to 300 keV too. The conventional scintillator is omitted, resulting in a reduction of image blurring and an increase in efficiency due to the much larger absorption thicknesses result. Also can be at a sufficiently fast readout speed (50 - 100 ns dead time) count single photons and determine their energy. Thus, the readout noise and the dark image correction omitted. Furthermore, one can detect or hide selectively certain areas of the X-ray energy spectrum by defining energy threshold values. This feature allows one the one hand, the discrimination of materials through the dual energy technology and on the other hand, the reduction of the detected scattered radiation, thereby increasing the contrast sensitivity. In order to use these advantages efficiently, a special calibration procedure is required, which must take into account time-dependent processes in the detector layer. Presented here are the properties of this new generation of X-ray detectors matrix compared to traditional indirect converting detectors based on reference measurements on fiber composite components and thick-walled steel tubes (up to 35 mm). Further possible applications in NDT are discussed with regard to the material discrimination especially within fiber composites (eg CFRP and GFRP).(Contains PowerPoint slides). [German] Der Einsatz von hochabsorbierenden Photoleitermaterialien (z.B. CdTe) zur Herstellung von Roentgen-Matrixdetektoren ermoeglicht seit einigen Jahren die direkte Konvertierung von Roentgenstrahlen in auswertbare elektrische Signale, auch fuer den ZfP-Energiebereich bis 300 keV. Die herkoemmliche Szintillatorschicht entfaellt, was eine Verringerung der Bildunschaerfe und eine Effizienzsteigerung aufgrund der deutlich groesseren Absorptionsdicken zur

  2. 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.

  3. Current trends in scintillator detectors and materials

    CERN Document Server

    Moses, W W

    2002-01-01

    The last decade has seen a renaissance in inorganic scintillator development for gamma ray detection. Lead tungstate (PbWO sub 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 sub 2 SiO sub 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 sub 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.

  4. An Experiment to Demonstrate Cherenkov / Scintillation Signal Separation

    CERN Document Server

    Caravaca, J; Land, B J; Wallig, J; Yeh, M; Gann, G D Orebi

    2016-01-01

    The ability to separately identify the Cherenkov and scintillation light components produced in scintillating mediums holds the potential for a major breakthrough in neutrino detection technology, allowing development of a large, low-threshold, directional detector with a broad physics program. The CHESS (CHErenkov / Scintillation Separation) experiment employs an innovative detector design with an array of small, fast photomultiplier tubes and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in a scintillating medium based on photon hit time and detected photoelectron density. This paper describes the physical properties and calibration of CHESS along with first results. The ability to reconstruct Cherenkov rings is demonstrated in a water target, and a time precision of 338 +/- 12 ps FWHM is achieved. Monte Carlo based predictions for the ring imaging sensitivity with a liquid scintillator target predict an efficiency for identifying Cherenkov hits of 94 +/- 1% and 81 +/- 1...

  5. Optimization of light collection from crystal scintillators for cryogenic experiments

    Energy Technology Data Exchange (ETDEWEB)

    Danevich, F.A., E-mail: danevich@kinr.kiev.ua [Institute for Nuclear Research, MSP 03680, Kyiv (Ukraine); Kobychev, R.V. [Institute for Nuclear Research, MSP 03680, Kyiv (Ukraine); National Technical University of Ukraine “Kyiv Polytechnic Institute”, 03056 Kyiv (Ukraine); Kobychev, V.V. [Institute for Nuclear Research, MSP 03680, Kyiv (Ukraine); Kyungpook National University, Daegu 702-701 (Korea, Republic of); Kraus, H. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Mikhailik, V.B. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Diamond Light Source, Harwell Science Campus, Didcot, OX11 0DE (United Kingdom); Mokina, V.M. [Institute for Nuclear Research, MSP 03680, Kyiv (Ukraine)

    2014-04-21

    High light collection efficiency is an important requirement in any application of scintillation detectors. The purpose of this study is to investigate the possibility for improving this parameter in cryogenic scintillation bolometers, which can be considered as promising detectors in experiments investigating neutrinoless double beta decay and dark matter. Energy resolutions and relative pulse amplitudes of scintillation detectors using ZnWO{sub 4} scintillation crystals of different shapes (cylinder ∅ 20×20 mm and hexagonal prism with diagonal 20 mm and height 20 mm), reflector materials and shapes, optical contact and surface properties (polished and diffused) were measured at room temperature. Propagation of optical photons in these experimental conditions was simulated using Geant4 and ZEMAX codes. The results of the simulations are found to be in good agreement with each other and with direct measurements of the crystals. This could be applied to optimize the geometry of scintillation detectors used in the cryogenic experiments.

  6. 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.

  7. 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.

  8. 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...

  9. Sub-aquatic response of a scintillator, fibre optic and silicon photomultiplier based radiation sensor

    Science.gov (United States)

    Jackson, Sarah F.; Monk, Stephen D.; Stanley, Steven J.; Lennox, Kathryn

    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®’ 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® to a highly controlled dose rate (ranging from 0 Sv h-1 to 320 Sv h-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.

  10. Preparation and performance study of a novel liquid scintillator with mixed solvent as the matrix

    Science.gov (United States)

    Zheng, Zhanlong; Zhu, Jiayi; Luo, Xuan; Xu, Yewei; Zhang, Qianfeng; Zhang, Xing; Bi, Yutie; Zhang, Lin

    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. 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.

  12. Ionization and scintillation of nuclear recoils in gaseous xenon

    CERN Document Server

    Renner, J; Goldschmidt, A; Matis, H S; Miller, T; Nakajima, Y; Nygren, D; Oliveira, C A B; Shuman, D; Álvarez, V; Borges, F I G; Cárcel, S; Castel, J; Cebrián, S; Cervera, A; Conde, C A N; Dafni, T; Dias, T H V T; Díaz, J; Esteve, R; Evtoukhovitch, P; Fernandes, L M P; Ferrario, P; Ferreira, A L; Freitas, E D C; Gil, A; Gómez, H; Gómez-Cadenas, J J; González-Díaz, D; Gutiérrez, R M; Hauptman, J; Morata, J A Hernando; Herrera, D C; Iguaz, F J; Irastorza, I G; Jinete, M A; Labarga, L; Laing, A; Liubarsky, I; Lopes, J A M; Lorca, D; Losada, M; Luzón, G; Marí, A; Martín-Albo, J; Martínez, A; Moiseenko, A; Monrabal, F; Monserrate, M; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Muñoz; da Luz, H Natal; Navarro, G; Nebot-Guinot, M; Palma, R; Pérez, J; Aparicio, J L Pérez; Ripoll, L; Rodríguez, A; Rodríguez, J; Santos, F P; Santos, J M F dos; Seguí, L; Serra, L; Simón, A; Sofka, C; Sorel, M; Toledo, J F; Tomás, A; Torrent, J; Tsamalaidze, Z; Veloso, J F C A; Villar, J A; Webb, R C; White, J; Yahlali, N

    2014-01-01

    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 $\\alpha$-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.

  13. 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.

  14. The application of a photon-counting camera in very sensitive, bioluminescence-enhanced detection systems for protein blotting. Ultrasensitive detection systems for protein blotting and DNA hybridization, II.

    Science.gov (United States)

    Hauber, R; Miska, W; Schleinkofer, L; Geiger, R

    1988-03-01

    A relatively simple, very sensitive bioluminescence-enhanced detection system for protein blots was described recently. This method utilizes antibodies conjugated with alkaline phosphatase. Alkaline phosphatase releases D-luciferin (Photinus pyralis) from D-luciferin-O-phosphate. Liberated D-luciferin reacts with luciferase, ATP and oxygen with light emission. The light produced is measured with a very sensitive photon counting camera (Argus 100), permitting visualization and localization of the alkaline phosphatase-conjugated antibodies on nitrocellulose sheets. Under non-optimized conditions the limit of detection is at present 5 to 500 fg of protein (rabbit immunoglobulin G), corresponding to 30 to 3 amol. The method is therefore 10(5) times more sensitive than other used at present.

  15. Non-destructive imaging of fragments of historical beeswax seals using high-contrast X-ray micro-radiography and micro-tomography with large area photon-counting detector array.

    Science.gov (United States)

    Karch, Jakub; Bartl, Benjamin; Dudak, Jan; Zemlicka, Jan; Krejci, Frantisek

    2016-12-01

    Historical beeswax seals are unique cultural heritage objects. Unfortunately, a number of historical sealing waxes show a porous structure with a strong tendency to stratification and embrittlement, which makes these objects extremely prone to mechanical damage. The understanding of beeswax degradation processes therefore plays an important role in the preservation and consequent treatment of these objects. Conventional methods applied for the investigation of beeswax materials (e.g. gas chromatography) are of a destructive nature or bring only limited information about the sample surface (microscopic techniques). Considering practical limitations of conventional methods and ethical difficulties connected with the sampling of the historical material, radiation imaging methods such as X-ray micro-tomography presents a promising non-destructive tool for the onward scientific research in this field. In this contribution, we present the application of high-contrast X-ray micro-radiography and micro-tomography for the investigation of beeswax seal fragments. The method is based on the application of the large area photon-counting detector recently developed at our institute. The detector combines the advantages of single-photon counting technology with a large field of view. The method, consequently, enables imaging of relatively large objects with high geometrical magnification. In the reconstructed micro-tomographies of investigated historical beeswax seals, we are able to reveal morphological structures such as stratification, micro-cavities and micro-fractures with spatial resolution down to 5μm non-destructively and with high imaging quality. The presented work therefore demonstrates that a combination of state-of-the-art hybrid pixel semiconductor detectors and currently available micro-focus x-ray sources makes it possible to apply X-ray micro-radiography and micro-tomography as a valuable non-destructive tool for volumetric beeswax seal morphological studies

  16. Measurement of Scintillation and Ionization Yield and Scintillation Pulse Shape from Nuclear Recoils in Liquid Argon

    CERN Document Server

    Cao, H; Avetisyan, R; Back, H O; Cocco, A G; DeJongh, F; Fiorillo, G; Galbiati, C; Grandi, L; Guardincerri, Y; Kendziora, C; Lippincott, W H; Love, C; Lyons, S; Manenti, L; Martoff, C J; Meng, Y; Montanari, D; Mosteiro, P; Olvitt, D; Pordes, S; Qian, H; Rossi, B; Saldanha, R; Sangiorgio, S; Siegl, K; Strauss, S Y; Tan, W; Tatarowicz, J; Walker, S; Wang, H; Watson, A W; Westerdale, S; Yoo, J

    2014-01-01

    We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase Liquid Argon Time Projection Chamber (LAr-TPC) to a low energy pulsed narrowband neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We report measurements of the scintillation and ionization yields for nuclear recoils with energies from 10.3 to 57.2 keV and for applied electric fields from 0 to 1000 V/cm. We also report the observation of an anti-correlation between scintillation and ionization from nuclear recoils, which is similar to the anti-correlation between scintillation and ionization from electron recoils. A comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field yielded a first evidence of sensitivity to direct...

  17. Liquid Scintillation Counting

    OpenAIRE

    Carlsson, Sten

    1993-01-01

    In liquid scintillation counting (LSC) we use the process of luminescense to detect ionising radiation emit$ed from a radionuclide. Luminescense is emission of visible light of nonthermal origin. 1t was early found that certain organic molecules have luminescent properties and such molecules are used in LSC. Today LSC is the mostwidespread method to detect pure beta-ernitters like tritium and carbon-14. 1t has unique properties in its efficient counting geometry, deteetability and the lack of...

  18. Li-containing scintillating bolometers for low background physics

    CERN Document Server

    Pattavina, L

    2013-01-01

    We present the performances of Li-based compounds used as scintillating bolometer for rare decay studies such as double-beta decay and direct dark matter investigations. The compounds are tested in a dilution refrigerator installed in the underground laboratory of Laboratori Nazionali del Gran Sasso (Italy). Low temperature scintillating properties are investigated by means of different radioactive sources, and the radio-purity level for internal contaminations are estimated for possible employment for next generation experiments.

  19. Li-containing scintillating bolometers for low background physics

    Directory of Open Access Journals (Sweden)

    Pattavina L.

    2014-01-01

    Full Text Available We present the performances of Li-based compounds used as scintillating bolometer for rare decay studies such as double-beta decay and direct dark matter investigations. The compounds are tested in a dilution refrigerator installed in the underground laboratory of Laboratori Nazionali del Gran Sasso (Italy. Low temperature scintillating properties are investigated by means of different radioactive sources, and the radio-purity level for internal contaminations are estimated for possible employment for next generation experiments.

  20. Structural Origins of Scintillation: Metal Organic Frameworks as a Nanolaboratory

    Science.gov (United States)

    2016-06-01

    orientation of scintillating groups has a direct effect upon the observed spectral and timing characteristics. A 2-dimensional layered MOF based...states and to elucidate the factors that contribute to favorable scintillation properties such as high luminosity, low self-absorption, and fast timing ...exhibit wavelength-dependent emission characteristics, longer emission decay time constants, and radioluminescence spectra that are red-shifted relative to

  1. PLASTIC SCINTILLATOR FOR RADIATION DOSIMETRY.

    Science.gov (United States)

    Kim, Yewon; Yoo, Hyunjun; Kim, Chankyu; Lim, Kyung Taek; Moon, Myungkook; Kim, Jongyul; Cho, Gyuseong

    2016-09-01

    Inorganic scintillators, composed of high-atomic-number materials such as the CsI(Tl) scintillator, are commonly used in commercially available a silicon diode and a scintillator embedded indirect-type electronic personal dosimeters because the light yield of the inorganic scintillator is higher than that of an organic scintillator. However, when it comes to tissue-equivalent dose measurements, a plastic scintillator such as polyvinyl toluene (PVT) is a more appropriate material than an inorganic scintillator because of the mass energy absorption coefficient. To verify the difference in the absorbed doses for each scintillator, absorbed doses from the energy spectrum and the calculated absorbed dose were compared. From the results, the absorbed dose of the plastic scintillator was almost the same as that of the tissue for the overall photon energy. However, in the case of CsI, it was similar to that of the tissue only for a photon energy from 500 to 4000 keV. Thus, the values and tendency of the mass energy absorption coefficient of the PVT are much more similar to those of human tissue than those of the CsI. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Scintillating balloon-enabled fiber-optic system for radionuclide imaging of atherosclerotic plaques.

    Science.gov (United States)

    Zaman, Raiyan T; Kosuge, Hisanori; Carpenter, Colin; Sun, Conroy; McConnell, Michael V; Xing, Lei

    2015-05-01

    Atherosclerosis underlies coronary artery disease, the leading cause of death in the United States and worldwide. Detection of coronary plaque inflammation remains challenging. In this study, we developed a scintillating balloon-enabled fiber-optic radionuclide imaging (SBRI) system to improve the sensitivity and resolution of plaque imaging using (18)F-FDG, a marker of vascular inflammation, and tested it in a murine model. The fiber-optic system uses a Complementary Metal-Oxide Silicon (CMOS) camera with a distal ferrule terminated with a wide-angle lens. The novelty of this system is a scintillating balloon in the front of the wide-angle lens to image light from the decay of (18)F-FDG emission signal. To identify the optimal scintillating materials with respect to resolution, we calculated the modulation transfer function of yttrium-aluminum-garnet doped with cerium, anthracene, and calcium fluoride doped with europium (CaF2:Eu) phosphors using an edge pattern and a thin-line optical phantom. The scintillating balloon was then fabricated from 10 mL of silicone RTV catalyst mixed with 1 mL of base and 50 mg of CaF2:Eu per mL. The addition of a lutetium oxyorthosilicate scintillating crystal (500 μm thick) to the balloon was also investigated. The SBRI system was tested in a murine atherosclerosis model: carotid-ligated mice (n = 5) were injected with (18)F-FDG, followed by ex vivo imaging of the macrophage-rich carotid plaques and nonligated controls. Confirmatory imaging of carotid plaques and controls was also performed by an external optical imaging system and autoradiography. Analyses of the different phosphors showed that CaF2:Eu enabled the best resolution of 1.2 μm. The SBRI system detected almost a 4-fold-higher radioluminescence signal from the ligated left carotid artery than the nonligated right carotid: 1.63 × 10(2) ± 4.01 × 10(1) vs. 4.21 × 10(1) ± 2.09 × 10(0) (photon counts), P = 0.006. We found no significant benefit to adding a

  3. Scintillation mechanism in stoichiometric cerium compounds

    Energy Technology Data Exchange (ETDEWEB)

    Wojtowicz, A.J.; Lempicki, A.; Berman, E. [Boston Univ., MA (United States). Dept. of Chemistry

    1992-12-31

    These materials constitute a new class of scintillator media, with high speed and high light output. This is illustrated using CeF{sub 3}, and CeP{sub 5}O{sub l4}. While speed, being limited by a radiative lifetime of an allowed d-f transition on the Ce{sup +3} ion, cannot be improved (without loss of the light output), the light output in both cases falls significantly below the estimated theoretical limit. To explain this we propose a mechanism of scintillation process, in which transfer of excitation energy from the lattice to the d-f electronic structure of Ce{sup +3} ions is absent and the light output of the scintillator is limited to the excitation energy directly intercepted by Ce ions. The efficiency depends, therefore, on the competition for holes between Ce{sup +3} ions and anions, determining the share of the total energy deposited by a high energy particle, which can be transformed into scintillation photons. The mechanism requires that the Ce ion has a stable 4+ charge state. Ionization of Ce{sup +3} is followed by capturing of an electron and creation of the Ce bound exciton. In the next step the energy of the bound exciton is transferred to the d-f structure of the Ce ion and, in the final step, a scintillation photon is emitted. The relatively high light output characteristic of these materials is due to the high concentration of Ce ions. The reasons for the lack of efficient energy transfer from the lattice may reside in large relaxation energies of lattice excitations. We use this model to discuss potential improvements in the light output of CeF{sub 3}.

  4. GPS Scintillation Analysis.

    Science.gov (United States)

    2007-11-02

    Rev. 2-89) Prescribed by ANSI Std. Z39-1 298-102 TABLE OF CONTENTS 1. INTRODUCTION 1 2. GPS COMPARISON WITH ALL-SKY IMAGES OVER AGUA VERDE...Depletions from 1 October 1994 2 3. GPS data from Agua Verde, Chile on the night of 1 October 1994 3 4. PL-SCINDA display of GPS ionospheric...comparison of GPS measurements with GOES8 L-band scintillation data, are discussed. 2. GPS COMPARISON WITH ALL-SKY IMAGES OVER AGUA VERDE, CHILE As

  5. Scintillating fiber detector

    CERN Document Server

    Vozak, Matous

    2016-01-01

    NA61 is one of the physics experiments at CERN dedicated to study hadron states coming from interactions of SPS beams with various targets. To determine the position of a secondary beam, three proportional chambers are placed along the beamline. However, these chambers tend to have slow response. In order to obtain more precise time information, use of another detector is being considered. Fast response and compact size is making scintillation fiber (SciFi) with silicon photomultiplier (Si-PM) read out a good candidate. This report is focused on analysing data from SciFi collected in a test beam at the beginning of July 2016.

  6. 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.

  7. Development of Radiation Hard Scintillators

    CERN Document Server

    Tiras, Emrah; Bilki, Burak; Winn, David; Onel, Yasar

    2016-01-01

    Modern high-energy physics experiments are in ever increasing need for radiation hard scintillators and detectors. In this regard, we have studied various radiation-hard scintillating materials such as Polyethylene Naphthalate (PEN), Polyethylene Terephthalate (PET), our prototype material Scintillator X (SX) and Eljen (EJ). Scintillation and transmission properties of these scintillators are studied using stimulated emission from a 334 nm wavelength UV laser with PMT before and after certain amount of radiation exposure. Recovery from radiation damage is studied over time. While the primary goal of this study is geared for LHC detector upgrades, these new technologies could easily be used for future experiments such as the FCC and ILC. Here we discuss the physics motivation, recent developments and laboratory measurements of these materials.

  8. Multiple-return single-photon counting of light in flight and sensing of non-line-of-sight objects at shortwave infrared wavelengths.

    Science.gov (United States)

    Laurenzis, Martin; Klein, Jonathan; Bacher, Emmanuel; Metzger, Nicolas

    2015-10-15

    Time-of-flight sensing with single-photon sensitivity enables new approaches for the localization of objects outside a sensor's field of view by analyzing backscattered photons. In this Letter, the authors have studied the application of Geiger-mode avalanche photodiode arrays and eye-safe infrared lasers, and provide experimental data of the direct visualization of backscattering light in flight, and direct vision and indirect vision of targets in line-of-sight and non-line-of-sight configurations at shortwave infrared wavelengths.

  9. Semiconductor High-Energy Radiation Scintillation Detector

    CERN Document Server

    Kastalsky, A; Spivak, B

    2006-01-01

    We propose a new scintillation-type detector in which high-energy radiation produces 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. The most important advantage of the proposed detector is its fast response time, about 1 ns, essentially limited only by the recombi...

  10. Use of silicon photodiode optically connected to scintillator in measurement of gamma dose rates

    Energy Technology Data Exchange (ETDEWEB)

    Gilar, O. (Tesla, Premysleni (Czechoslovakia). Vyzkumny Ustav Pristroju Jaderne Techniky); Petr, I. (Ceske Vysoke Uceni Technicke, Prague (Czechoslovakia). Fakulta Jaderna a Fysikalne Inzenyrska)

    1984-06-01

    Contributing to the signal which is produced in the photodiode by direct interaction with radiation may also be light photons produced by scintillation in the scintillator which is in optical contact with the photodiode. The scintillator/photodiode combination may increase sensitivity in comparison with the photodiode alone. The energy dependence of the detector will change according to the scintillator material and size. The configuration is described of a detector with CsI(Tl) scintillator. The detector is suitable for medium and large dose rates, the limiting factor for measuring small dose rates is the intensity of the photodiode dark current and its temperature dependence. A higher sensitivity of the designed detector configuration may be achieved by selecting a scintillator with a more suitable emission spectrum or by technological modifications of the photodiode.

  11. Fracture-resistant lanthanide scintillators

    Science.gov (United States)

    Doty, F. Patrick

    2011-01-04

    Lanthanide halide alloys have recently enabled scintillating gamma ray spectrometers comparable to room temperature semiconductors (lanthanide alloy substitution, while preserving scintillation, have been demonstrated. Isovalent alloys having nominal compositions of comprising Al, Ga, Sc, Y, and In dopants as well as aliovalent alloys comprising Ca, Sr, Zr, Hf, Zn, and Pb dopants were prepared. All of these alloys exhibit bright fluorescence under UV excitation, with varying shifts in the spectral peaks and intensities relative to pure CeBr.sub.3. Further, these alloys scintillate when coupled to a photomultiplier tube (PMT) and exposed to .sup.137Cs gamma rays.

  12. Scintillation counter with MRS APD light readout

    CERN Document Server

    INSPIRE-00061314; Malkevich, D.; Martemyanov, A.; Ryabinin, M.; Smirnitsky, A.; Voloshin, K.; Bondarenko, G.; Golovin, V.; Grigoriev, E.

    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 1 mm^2 sensitive areas. START is assembled from a 15 x 15 x 1 cm^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 2-3 kUSD/m^2.

  13. Development of a reference liquid scintillation cocktail

    CSIR Research Space (South Africa)

    Van Wyn Gaardt, WM

    2006-02-01

    Full Text Available of a scintillator dissolved in an organic solvent. The so-called scintillator solute is a material which emits a weak light flash or scintillation upon interaction with a certain quanta of radiation – the intensity of this scintillation being a... to prepare preliminary liquid scintillation cocktails. Figure 3: Maximum deviations observed between repeat measurements of the same source, displayed in red for Ultima Gold, green for XP, yellow for XI and blue for XPI. Figure 4: The counting...

  14. Measurement of scintillation and ionization yield and scintillation pulse shape from nuclear recoils in liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Cao, H.; Alexander, T.; Aprahamian, A.; Avetisyan, R.; Back, H. O.; Cocco, A. G.; DeJongh, F.; Fiorillo, G.; Galbiati, C.; Grandi, L.; Guardincerri, Y.; Kendziora, C.; Lippincott, W. H.; Love, C.; Lyons, S.; Manenti, L.; Martoff, C. J.; Meng, Y.; Montanari, D.; Mosteiro, P.; Olvitt, D.; Pordes, S.; Qian, H.; Rossi, B.; Saldanha, R.; Sangiorgio, S.; Siegl, K.; Strauss, S. Y.; Tan, W.; Tatarowicz, J.; Walker, S.; Wang, H.; Watson, A. W.; Westerdale, S.; Yoo, J.

    2015-05-01

    We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0 to 970 V / cm . For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V / cm . We also report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from 83 m Kr internal conversion electrons is comparable to that from 207 Bi conversion electrons, we obtained the numbers of excitons ( N ex ) and ion pairs ( N i ) and their ratio ( N ex / N i ) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.

  15. 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

  16. Radar measurement of ionospheric scintillation in the polar region

    Science.gov (United States)

    Knepp, Dennis L.

    2015-10-01

    This paper considers several estimators that use radar data to measure the S4 scintillation index that characterizes the severity of amplitude scintillation that may occur during RF propagation through ionospheric irregularities. S4 is defined to be the standard deviation of the fluctuations in received power normalized by division by the mean power. Estimates of S4 are based on radar returns obtained during track of targets which may themselves have intrinsic radar cross-section fluctuations. Key to this work is the consideration of thresholding, which is used in many radars to remove (from further processing) signals whose SNR is considered too low. We consider several estimators here. The "direct" estimator attempts to estimate S4 through the direct calculation of the mean and standard deviation of the SNR from a number of radar returns. The maximum likelihood (ML) estimator uses multiple hypothesis testing and the assumption of Nakagami-m statistics to estimate the scintillation index that best fits the radar returns from some number of pulses. The ML estimator has perfect knowledge of the number of radar returns that are below the threshold. The direct estimator is accurate for the case where there is no threshold and there are many returns or samples from which to estimate S4. However, the direct estimator is flawed (especially for strong scintillation) if deep fades that fall below the radar threshold are ignored. The modified ML estimator here is based on the ML technique but is useful if the count of missed returns is unavailable. We apply the modified ML estimator to several years of radar tracks of large calibration satellites to obtain the statistics of UHF scintillation as viewed from the early warning radar at Thule, Greenland. One-way S4 was measured from 5000 low Earth orbit tracks during the 3 year period after solar maximum in May 2000. The data are analyzed to quantify the exceedance or the level of scintillation experienced at various

  17. 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.

  18. A PET detector prototype based on digital SiPMs and GAGG scintillators.

    Science.gov (United States)

    Schneider, Florian R; Shimazoe, Kenji; Somlai-Schweiger, Ian; Ziegler, Sibylle I

    2015-02-21

    Silicon Photomultipliers (SiPM) are interesting light sensors for Positron Emission Tomography (PET). The detector signal of analog SiPMs is the total charge of all fired cells. Energy and time information have to be determined with dedicated readout electronics. Philips Digital Photon Counting has developed a SiPM with added electronics on cell level delivering a digital value of the time stamp and number of fired cells. These so called Digital Photon Counters (DPC) are fully digital devices. In this study, the feasibility of using DPCs in combination with LYSO (Lutetium Yttrium Oxyorthosilicate) and GAGG (Gadolinium Aluminum Gallium Garnet) scintillators for PET is tested. Each DPC module has 64 channels with 3.2 × 3.8775 mm(2), comprising 3200 cells each. GAGG is a recently developed scintillator (Zeff = 54, 6.63 g cm(-3), 520 nm peak emission, 46 000 photons MeV(-1), 88 ns (92%) and 230 ns (8%) decay times, non-hygroscopic, chemically and mechanically stable). Individual crystals of 2 × 2 × 6 mm(3) were coupled onto each DPC pixel. LYSO coupled to the DPC results in a coincidence time resolution (CTR) of 171 ps FWHM and an energy resolution of 12.6% FWHM at 511 keV. Using GAGG, coincidence timing is 310 ps FWHM and energy resolution is 8.5% FWHM. A PET detector prototype with 2 DPCs equipped with a GAGG array matching the pixel size (3.2 × 3.8775 × 8 mm(3)) was assembled. To emulate a ring of 10 modules, objects are rotated in the field of view. CTR of the PET is 619 ps and energy resolution is 9.2% FWHM. The iterative MLEM reconstruction is based on system matrices calculated with an analytical detector response function model. A phantom with rods of different diameters filled with (18)F was used for tomographic tests.

  19. A PET detector prototype based on digital SiPMs and GAGG scintillators

    Science.gov (United States)

    Schneider, Florian R.; Shimazoe, Kenji; Somlai-Schweiger, Ian; Ziegler, Sibylle I.

    2015-02-01

    Silicon Photomultipliers (SiPM) are interesting light sensors for Positron Emission Tomography (PET). The detector signal of analog SiPMs is the total charge of all fired cells. Energy and time information have to be determined with dedicated readout electronics. Philips Digital Photon Counting has developed a SiPM with added electronics on cell level delivering a digital value of the time stamp and number of fired cells. These so called Digital Photon Counters (DPC) are fully digital devices. In this study, the feasibility of using DPCs in combination with LYSO (Lutetium Yttrium Oxyorthosilicate) and GAGG (Gadolinium Aluminum Gallium Garnet) scintillators for PET is tested. Each DPC module has 64 channels with 3.2 × 3.8775 mm2, comprising 3200 cells each. GAGG is a recently developed scintillator (Zeff = 54, 6.63 g cm-3, 520 nm peak emission, 46 000 photons MeV-1, 88 ns (92%) and 230 ns (8%) decay times, non-hygroscopic, chemically and mechanically stable). Individual crystals of 2 × 2 × 6 mm3 were coupled onto each DPC pixel. LYSO coupled to the DPC results in a coincidence time resolution (CTR) of 171 ps FWHM and an energy resolution of 12.6% FWHM at 511 keV. Using GAGG, coincidence timing is 310 ps FWHM and energy resolution is 8.5% FWHM. A PET detector prototype with 2 DPCs equipped with a GAGG array matching the pixel size (3.2 × 3.8775 × 8 mm3) was assembled. To emulate a ring of 10 modules, objects are rotated in the field of view. CTR of the PET is 619 ps and energy resolution is 9.2% FWHM. The iterative MLEM reconstruction is based on system matrices calculated with an analytical detector response function model. A phantom with rods of different diameters filled with 18F was used for tomographic tests.

  20. The theory and practice of scintillation counting

    CERN Document Server

    Birks, John Bettely

    1964-01-01

    The Theory and Practice of Scintillation Counting is a comprehensive account of the theory and practice of scintillation counting. This text covers the study of the scintillation process, which is concerned with the interactions of radiation and matter; the design of the scintillation counter; and the wide range of applications of scintillation counters in pure and applied science. The book is easy to read despite the complex nature of the subject it attempts to discuss. It is organized such that the first five chapters illustrate the fundamental concepts of scintillation counting. Chapters 6

  1. The Quanta Image Sensor: Every Photon Counts

    Directory of Open Access Journals (Sweden)

    Eric R. Fossum

    2016-08-01

    Full Text Available The Quanta Image Sensor (QIS was conceived when contemplating shrinking pixel sizes and storage capacities, and the steady increase in digital processing power. In the single-bit QIS, the output of each field is a binary bit plane, where each bit represents the presence or absence of at least one photoelectron in a photodetector. A series of bit planes is generated through high-speed readout, and a kernel or “cubicle” of bits (x, y, t is used to create a single output image pixel. The size of the cubicle can be adjusted post-acquisition to optimize image quality. The specialized sub-diffraction-limit photodetectors in the QIS are referred to as “jots” and a QIS may have a gigajot or more, read out at 1000 fps, for a data rate exceeding 1 Tb/s. Basically, we are trying to count photons as they arrive at the sensor. This paper reviews the QIS concept and its imaging characteristics. Recent progress towards realizing the QIS for commercial and scientific purposes is discussed. This includes implementation of a pump-gate jot device in a 65 nm CIS BSI process yielding read noise as low as 0.22 e− r.m.s. and conversion gain as high as 420 µV/e−, power efficient readout electronics, currently as low as 0.4 pJ/b in the same process, creating high dynamic range images from jot data, and understanding the imaging characteristics of single-bit and multi-bit QIS devices. The QIS represents a possible major paradigm shift in image capture.

  2. RULLI/a Photon Counting Imager

    Energy Technology Data Exchange (ETDEWEB)

    Albright, K.L.; Smith, R.C.; Ho, C.; Wilson, S.K.; Bradley, J.; Bird, A.; Casperson, D.E.; Hindman, M.; Whitaker, R.; Theiler, J.; Scarlett, R.; Priedhorsky, W.C.

    1998-10-19

    The Remote Low Light Imaging (RULLI) system responds to individual photons using a modification to conventional image intensifier technology and fast timing electronics. Each photon received at the detector is resolved in three dimensions (X, Y, and time). The accumulation of photons over time allows the system to image with very low light levels, such as starlight illumination. Using a low power pulsed laser and very fine time discrimination, three dimensional imaging has been accomplished with a vertical resolution of five cm.

  3. What Is the Best Method to Fit Time-Resolved Data? A Comparison of the Residual Minimization and the Maximum Likelihood Techniques As Applied to Experimental Time-Correlated, Single-Photon Counting Data.

    Science.gov (United States)

    Santra, Kalyan; Zhan, Jinchun; Song, Xueyu; Smith, Emily A; Vaswani, Namrata; Petrich, Jacob W

    2016-03-10

    The need for measuring fluorescence lifetimes of species in subdiffraction-limited volumes in, for example, stimulated emission depletion (STED) microscopy, entails the dual challenge of probing a small number of fluorophores and fitting the concomitant sparse data set to the appropriate excited-state decay function. This need has stimulated a further investigation into the relative merits of two fitting techniques commonly referred to as "residual minimization" (RM) and "maximum likelihood" (ML). Fluorescence decays of the well-characterized standard, rose bengal in methanol at room temperature (530 ± 10 ps), were acquired in a set of five experiments in which the total number of "photon counts" was approximately 20, 200, 1000, 3000, and 6000 and there were about 2-200 counts at the maxima of the respective decays. Each set of experiments was repeated 50 times to generate the appropriate statistics. Each of the 250 data sets was analyzed by ML and two different RM methods (differing in the weighting of residuals) using in-house routines and compared with a frequently used commercial RM routine. Convolution with a real instrument response function was always included in the fitting. While RM using Pearson's weighting of residuals can recover the correct mean result with a total number of counts of 1000 or more, ML distinguishes itself by yielding, in all cases, the same mean lifetime within 2% of the accepted value. For 200 total counts and greater, ML always provides a standard deviation of <10% of the mean lifetime, and even at 20 total counts there is only 20% error in the mean lifetime. The robustness of ML advocates its use for sparse data sets such as those acquired in some subdiffraction-limited microscopies, such as STED, and, more importantly, provides greater motivation for exploiting the time-resolved capacities of this technique to acquire and analyze fluorescence lifetime data.

  4. Cherenkov and Scintillation Light Separation in Organic Liquid Scintillators

    CERN Document Server

    Caravaca, J; Land, B J; Yeh, M; Gann, G D Orebi

    2016-01-01

    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 2g/L of PPO as a fluor (LAB/PPO). This is the first such demonstration for 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 0.75 +/- 0.25 ns.

  5. Molecular origins of scintillation in organic scintillators (Conference Presentation)

    Science.gov (United States)

    Feng, Patrick; Mengesha, Wondwosen; Myllenbeck, Nicholas

    2016-09-01

    Organic-based scintillators are indispensable materials for radiation detection owing to their high sensitivity to fast neutrons, low cost, and tailorable properties. There has been a recent resurgence of interest in organic scintillators due to exciting discoveries related to neutron discrimination and gamma-ray spectroscopy, which represent capabilities previously thought not possible in these materials. I will discuss our development of crystalline and polymer-based scintillators for these applications. Structure-property relationships related to intermolecular interactions and host-guest electronic exchange will be discussed in the context of energy-transfer pathways relevant to scintillation. An emphasis will be placed on the rational design of these materials, as guided by first principles and DFT calculations. Two related topics will be discussed: 1) Incorporation of organometallic triplet-harvesting additives to plastic scintillator matrices to confer a 'two-state' (singlet and triplet) luminescence signature to different types of ionizing radiation. This approach relies upon energetic and spatial overlap between the donor and acceptor excited states for efficient electronic exchange. Key considerations also include synthetic modification of the luminescence spectra and kinetics, as well as the addition of secondary additives to increase the recombination efficiency. 2) Design of organotin-containing plastic scintillators as a route towards gamma-ray spectroscopy. Organometallic compounds were selected on the basis of distance-dependent quenching relationships, phase compatibility with the polymer matrix, and the gamma-ray cross sections. This approach is guided by molecular modeling and radiation transport modeling to achieve the highest possible detection sensitivity luminescence intensity.

  6. 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.

  7. Room-temperature semiconductors and scintillators for planetary instruments

    CERN Document Server

    Schweitzer, J S

    1999-01-01

    Room temperature semiconductors introduce some exciting potential for use in instruments designed for planetary measurements. It is important, however, to consider carefully the different types of measurement environments. In some cases room temperature semiconductors provide significant advantages over scintillators, while in some cases scintillators still have advantages over room temperature semiconductors. A number of instrumentation applications for detecting X-rays and gamma rays are considered. By focusing on the physical properties of both types of detectors, it is possible to better understand how each type of detector can best be used for measurements from satellites and directly on planetary bodies.

  8. 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...

  9. Radiopure Metal-Loaded Liquid Scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Rosero, Richard [Brookhaven National Lab. (BNL), Upton, NY (United States). Chemistry Dept.; Yeh, Minfang [Brookhaven National Lab. (BNL), Upton, NY (United States). Chemistry Dept.

    2015-03-18

    Metal-loaded liquid scintillator plays a key role in particle and nuclear physics experiments. The applications of metal ions in various neutrino experiments and the purification methods for different scintillator components are discussed in this paper.

  10. New halide scintillators for gamma ray detection

    NARCIS (Netherlands)

    Alekhin, M. S.

    2013-01-01

    Scintillators are used for the detection of ionizing radiation. Despite decades of intensive search and numerous compounds discovered, there is still a need for materials with improved properties. Recently, several new scintillators with excellent light yield, energy resolution, and proportionality

  11. 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.

  12. Ionospheric precursors to scintillation activity

    Directory of Open Access Journals (Sweden)

    Paul S.J. Spencer

    2014-03-01

    Full Text Available Ionospheric scintillation is the rapid fluctuation of both phase and amplitude of trans-ionospheric radio waves due to small scale electron density irregularities in the ionosphere. Prediction of the occurrence of scintillation at L band frequencies is needed to mitigate the disruption of space-based communication and navigation systems. The purpose of this paper is to present a method of using tomographic inversions of the ionospheric electron density obtained from ground-based GPS data to infer the location and strength of the post-sunset plasma drift vortex. This vortex is related to the pre-reversal enhancement in the eastwards electric field which has been correlated to the subsequent occurrence of scintillation.

  13. Scintillation detectors in computerized tomography

    Energy Technology Data Exchange (ETDEWEB)

    Gilar, O.; Pavlicek, Z.; Jursova, L. (Tesla, Premysleni (Czechoslovakia). Vyzkumny Ustav Pristroju Jaderne Techniky)

    1984-07-01

    A new scintillator, Bi/sub 4/Ge/sub 3/O/sub 12/ (BGO), was tested for use in the detection part of computerized tomographs. In comparison with the NaI(Tl) scintillator it has a three-fold mass stopping power and allows the detection of medium and high energy gamma radiation with a higher detection efficiency, i.e., for the same detection efficiency its size is much smaller. Some other mechanical, physical and optical parameters of the BGO scintillator are given. BGO is prospective for use in high energy spectrometry and may replace NaI(Tl) wherever the following parameters are significant: crystal size, detection efficiency for gamma radiation, and good spatial resolution.

  14. Impact of geometry on light collection efficiency of scintillation detectors for cryogenic rare event searches

    Energy Technology Data Exchange (ETDEWEB)

    Danevich, F.A.; Kobychev, V.V. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Kobychev, R.V. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); National Technical University of Ukraine “Kyiv Polytechnic Institute”, 03056 Kyiv (Ukraine); Kraus, H. [Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Mikhailik, V.B., E-mail: vmikhai@hotmail.com [Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Diamond Light Source, Didcot OX11 0DE (United Kingdom); Mokina, V.M. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Solsky, I.M. [Scientific Research Company CARAT, 79031 Lviv (Ukraine)

    2014-10-01

    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{sub 4} crystal scintillators. A comparison of simulated and measured values of light output shows good agreement.

  15. Study of micro pixel photon counters for a high granularity scintillator-based hadron calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    D' Ascenzo, N. [Hamburg Univ. (Germany)]|[Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Eggemann, A.; Garutti, E. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2007-11-15

    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.)

  16. Characterization of liquid scintillation detectors

    CERN Document Server

    Schmidt, D; Böttger, R; Klein, H; Lebreton, L; Neumann, S; Nolte, R; Pichenot, G

    2002-01-01

    Five scintillation detectors of different scintillator size and type were characterized. The pulse height scale was calibrated in terms of electron light output units using photon sources. The response functions for time-of-flight (TOF)-selected monoenergetic neutrons were experimentally determined and also simulated with the NRESP code over a wide energy range. A comparison of the measured and calculated response functions allows individual characteristics of the detectors to be determined and the response matrix to be reliably derived. Various applications are discussed.

  17. 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.

  18. 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.

  19. 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.

  20. Growth and scintillation properties of 3 in. diameter Ce doped Gd3Ga3Al2O12 scintillation single crystal

    Science.gov (United States)

    Kamada, Kei; Shoji, Yasuhiro; Kochurikhin, Vladimir V.; Okumura, Satoshi; Yamamoto, Seiichi; Nagura, Aya; Yeom, Jung Yeol; Kurosawa, Shunsuke; Yokota, Yuui; Ohashi, Yuji; Nikl, Martin; Yoshikawa, Akira

    2016-10-01

    The 3 in. size Ce1%:Gd3Al2Ga3O12 single crystals were prepared by the Czochralski (Cz) method. Optical constants were measured. Chemical composition analysis and uniformity of scintillation decay and light yield along growth direction were evaluated. The timing resolution measurement for a pair of 3 mm×3 mm×3 mm size Ce:GAGG scintillator crystals was performed using Si-PMs.

  1. 基于时间相关单光子计数的离线式g-STED超分辨显微术%Super Resolution Microscopy of Offline g-STED Microscopy Based on Time-Correlated Single Photon Counting

    Institute of Scientific and Technical Information of China (English)

    郝翔; 匡翠方; 顾兆泰; 李帅; 刘旭

    2013-01-01

    提出了一种离线式基于时间门的荧光受激发射损耗(g-STED)显微方法.基于在强光照条件下荧光寿命缩短的理论模型,在常规STED架构基础上,使用时间相关单光子记数(TCSPC)算法获取图像的荧光寿命信息,离线设置合理的时间门阈值,丢弃短寿命信号数据,对荧光信号有效点扩展函数(PSF)进行压缩,达到超分辨显微的目的.与传统STED显微术相比,此方法所需光功率大幅度降低,减少了荧光漂白及光毒性;离线式处理则同时增加了时间门设置的灵活性.在实验中,使用45 rnW的连续STED光,最终获取了约80 nm的图像空间分辨率.进一步对时间门的设置对获取图像信号的分辨率和信噪比的影响进行了讨论.%The offline time-gated stimulated emission depletion (g-STED) microscopy, which is based on time-correlated single photon counting (TCSPC) algorithm, is proposed. As STED beam can eliminate the ratio of spontaneous fluorescent emission while reducing the fluorescence lifetime, the lifetime of fluorescent signals in the center of excitation focal spot and that in the surrounding doughnut area which are overlap by the STED focal spot are significant different. Based on this principle, in a general continuous wave STED (CW-STED), the fluorescent lifetimes of the whole imaging region are calculated by TCSPC, and the signals with shorter lifetime are discarded after all data recorded. The effective point spread function (PSF) of each fluorescent labels are shrinked in order to enhance the resolution. Compared with traditional ones, this offline g-STED not only decreases the incident intensity of laser to avoid the risk of fluorescence photobleaching and optical toxicity, but also increases the flexibility of time-gate manipulation. A spatial resolution of 80 nm is obtained in the experiment when only 45 mW STED beam is introduced. The potential influences of time-gate selection to the resolution and signal-to-noise ratio

  2. A 1.5k x 1.5k class photon counting HgCdTe linear avalanche photo-diode array for low background space astronomy in the 1-5micron infrared

    Science.gov (United States)

    Hall, Donald

    Under a current award, NASA NNX 13AC13G "EXTENDING THE ASTRONOMICAL APPLICATION OF PHOTON COUNTING HgCdTe LINEAR AVALANCHE PHOTODIODE ARRAYS TO LOW BACKGROUND SPACE OBSERVATIONS" UH has used Selex SAPHIRA 320 x 256 MOVPE L-APD HgCdTe arrays developed for Adaptive Optics (AO) wavefront (WF) sensing to investigate the potential of this technology for low background space astronomy applications. After suppressing readout integrated circuit (ROIC) glow, we have placed upper limits on gain normalized dark current of 0.01 e-/sec at up to 8 volts avalanche bias, corresponding to avalanche gain of 5, and have operated with avalanche gains of up to several hundred at higher bias. We have also demonstrated detection of individual photon events. The proposed investigation would scale the format to 1536 x 1536 at 12um (the largest achievable in a standard reticule without requiring stitching) while incorporating reference pixels required at these low dark current levels. The primary objective is to develop, produce and characterize a 1.5k x 1.5k at 12um pitch MOVPE HgCdTe L-APD array, with nearly 30 times the pixel count of the 320 x 256 SAPHIRA, optimized for low background space astronomy. This will involve: 1) Selex design of a 1.5k x 1.5k at 12um pitch ROIC optimized for low background operation, silicon wafer fabrication at the German XFab foundry in 0.35 um 3V3 process and dicing/test at Selex, 2) provision by GL Scientific of a 3-side close-buttable carrier building from the heritage of the HAWAII xRG family, 3) Selex development and fabrication of 1.5k x 1.5k at 12 um pitch MOVPE HgCdTe L-APD detector arrays optimized for low background applications, 4) hybridization, packaging into a sensor chip assembly (SCA) with initial characterization by Selex and, 5) comprehensive characterization of low background performance, both in the laboratory and at ground based telescopes, by UH. The ultimate goal is to produce and eventually market a large format array, the L

  3. Vernier型光子计数探测器阳极电容仿真与试验研究∗%Simulation and exp eriment for electro de capacitance based on Vernier ano de photon counting detector

    Institute of Scientific and Technical Information of China (English)

    邢妍; 陈波; 王海峰; 张宏吉; 何玲平; 金方圆

    2015-01-01

    According to the principle of Vernier anode photon counting detector, in this paper we discuss a decoding algorithm of calculating centroid location and interelectrode capacitance between electrodes, which has a close relationship with preamplifier circuit noise. Based on the Poisson’s equation, the theoretical model of Vernier anode is established. The method of calculating the irregular shape uniplanar self-capacitance and interelectrode capacitance between electrodes using ANSYS finite element analysis is introduced. In addition, a Vernier anode plate is manufactured with picosecond laser micromachining process on a 1.5 mm thick quartz substrate with gold film as conductors. The Vernier anode pattern has a pitch of 9.9 mm, an active area of 19.8 mm × 19.8 mm, insulation channel depth of 10 µm, and insulation channel width of 30 µm. Comparing the simulated capacitances with the measured capacitances, the validity of the three-dimensional finite-element method is proved. A simulation study on the effects of substrate permittivity, insulation channel width and depth on capacitance change is carried out. The simulation result provides a basis for structure design of Vernier anodes.%根据Vernier型光子技术探测器的工作原理,论述了电子云质心解码与阳极面板形成的微小极间电容和电路前端噪声有着密切的关系;根据泊松方程,建立了Vernier阳极的数学模型。利用有限元软件ANSYS计算出同面多电极不规则图形的电容值与极间电容值,解决了如何计算不规则形状电容值的问题;利用皮秒激光器在镀有金膜的石英基底上刻蚀出与仿真参数一致的Vernier型阳极,并测量其电容值。将测量电容值与仿真值进行比较,验证了建立模型的正确性,优化了Vernier阳极的设计参数。

  4. Improved contrast and spatial resolution with Single Photon Counting (SPC) for an area x-ray imager, the newly developed high-resolution Micro-Angiographic Fluoroscopic (MAF) detector.

    Science.gov (United States)

    Jain, Amit; Kuhls-Gilcrist, Andrew; Bednarek, Daniel R; Rudin, Stephen

    2009-12-31

    Although in radiological imaging, the prevailing mode of acquisition is the integration of the energy deposited by all x-rays absorbed in the imaging detector, much improvement in image spatial and contrast resolution could be achieved if each individual x-ray photon were detected and counted separately. In this work we compare the conventional energy integration (EI) mode with the new single photon counting (SPC) mode for a recently developed high-resolution Micro-Angiographic Fluoroscopic (MAF) detector, which is uniquely capable of both modes of operation. The MAF has 1024×1024 pixels of 35 microns effective size and is capable of real-time imaging at 30 fps. The large variable gain of its light image intensifier (LII) provides quantum limited operation with essentially no additive instrumentation noise and enables the MAF to operate in both EI and the very sensitive low-exposure SPC modes. We used high LII gain with very low exposure (SPC mode and higher exposure per frame with lower gain for EI mode. Multiple signal-thresholded frames were summed in SPC mode to provide an integrated frame with the same total exposure as EI mode. A heavily K-edge filtered x-ray beam (average energy of 31 keV) was used to provide a nearly monochromatic spectrum. The MTF measured using a standard slit method showed a dramatic improvement for the SPC mode over the EI mode at all frequencies. Images of a line pair phantom also showed improved spatial resolution with 12 lp/mm visible in SPC mode compared to only 8 lp/mm in EI mode. In SPC mode, images of human distal and middle phalanges showed the trabecular structures of the bone with far better contrast and detail. These improvements with the SPC mode should be advantageous for clinical applications where high resolution and/or high contrast are essential such as in mammography and extremity imaging as well as for dual modality applications, which combine nuclear medicine and x-ray imaging using a single detector.

  5. 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.

  6. Extruded plastic scintillator for MINERvA

    Energy Technology Data Exchange (ETDEWEB)

    Pla-Dalmau, Anna; Bross, Alan D.; /Fermilab; Rykalin, Victor V.; Wood, Brian M.; /NICADD, DeKalb

    2005-11-01

    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.

  7. New Scintillation Detectors for PET

    NARCIS (Netherlands)

    Shah, K.S.

    2010-01-01

    The focus of this thesis is on new detection technologies that can be used in advancing nuclear medicine modalities, particularly positron emission tomography (PET). Several detection technologies are covered in this thesis. First, new Ce3+ doped rare earth trihalide scintillators that can be used

  8. New Scintillation Detectors for PET

    NARCIS (Netherlands)

    Shah, K.S.

    2010-01-01

    The focus of this thesis is on new detection technologies that can be used in advancing nuclear medicine modalities, particularly positron emission tomography (PET). Several detection technologies are covered in this thesis. First, new Ce3+ doped rare earth trihalide scintillators that can be used i

  9. Complex Dynamics of Equatorial Scintillation

    Science.gov (United States)

    Piersanti, Mirko; Materassi, Massimo; Forte, Biagio; Cicone, Antonio

    2017-04-01

    Radio power scintillation, namely highly irregular fluctuations of the power of trans-ionospheric GNSS signals, is the effect of ionospheric plasma turbulence. The scintillation patterns on radio signals crossing the medium inherit the ionospheric turbulence characteristics of inter-scale coupling, local randomness and large time variability. On this basis, the remote sensing of local features of the turbulent plasma is feasible by studying radio scintillation induced by the ionosphere. The distinctive character of intermittent turbulent media depends on the fluctuations on the space- and time-scale statistical properties of the medium. Hence, assessing how the signal fluctuation properties vary under different Helio-Geophysical conditions will help to understand the corresponding dynamics of the turbulent medium crossed by the signal. Data analysis tools, provided by complex system science, appear to be best fitting to study the response of a turbulent medium, as the Earth's equatorial ionosphere, to the non-linear forcing exerted by the Solar Wind (SW). In particular we used the Adaptive Local Iterative Filtering, the Wavelet analysis and the Information theory data analysis tool. We have analysed the radio scintillation and ionospheric fluctuation data at low latitude focusing on the time and space multi-scale variability and on the causal relationship between forcing factors from the SW environment and the ionospheric response.

  10. Recent progress of MPPC-based scintillation detectors in high precision X-ray and gamma-ray imaging

    Science.gov (United States)

    Kataoka, J.; Kishimoto, A.; Fujita, T.; Nishiyama, T.; Kurei, Y.; Tsujikawa, T.; Oshima, T.; Taya, T.; Iwamoto, Y.; Ogata, H.; Okochi, H.; Ohsuka, S.; Ikeda, H.; Yamamoto, S.

    2015-06-01

    The multi-pixel photon counter (MPPC) is a promising light sensor for various applications, not only in physics experiments but also in nuclear medicine, industry, and even high-energy astrophysics. In this paper, we present the current status and most recent progress of the MPPC-based scintillation detectors, such as (1) a high-precision X-ray and gamma-ray spectral image sensor, (2) next-generation PET detectors with MRI, TOF, and DOI measurement capabilities, and (3) a compact gamma camera for environmental radiation surveys. We first present a new method of fabricating a Ce:GAGG scintillator plate (1 or 2 mm thick) with ultra-fine resolution (0.2 mm/pixel), cut using a dicing saw to create 50 μm wide micro-grooves. When the plate is optically coupled with a large-area MPPC array, excellent spatial resolution of 0.48 mm (FWHM) and energy resolution of 14% (FWHM) are obtained for 122 keV gamma rays. Hence, the detector can act as a convenient "multi-color" imaging device that can potentially be used for future SPECT and photon-counting CT. We then show a prototype system for a high-resolution MPPC-based PET scanner that can realize ≃1 mm (FWHM) spatial resolution, even under a strong magnetic field of 4.7 T. We develop a front-end ASIC intended for future TOF-PET scanner with a 16-channel readout that achieves a coincidence time resolution of 489 ps (FWHM). A novel design for a module with DOI-measurement capability for gamma rays is also presented by measuring the pulse height ratio of double-sided MPPCs coupled at both ends of scintillation crystal block. Finally, we present the concept of a two-plane Compton camera consisting of Ce:GAGG scintillator arrays coupled with thin MPPC arrays. As a result of the thin and compact features of the MPPC device, the camera not only achieves a small size (14×14×15 cm3) and light weight (1.9 kg) but also excellent sensitivity, compared to the conventional PMT-based pinhole camera used in Fukushima. Finally, we briefly

  11. Investigation of behavior of scintillator detector of Alborz observatory array using Monte Carlo method with Geant4 code

    Directory of Open Access Journals (Sweden)

    M. Abbasian Motlagh

    2014-04-01

    Full Text Available For their appropriate temporal resolution, scintillator detectors are used in the Alborz observatory. In this work, the behavior of the scintillation detectors for the passage of electrons with different energies and directions were studied using the simulation code GEANT4. Pulse shapes of scintillation light, and such characteristics as the total number of photons, the rise time and the falling time for the optical pulses were computed for the passage of electrons with energies of 10, 100 and 1000 MeV. Variations of the characteristics of optical pulse of scintillation with incident angle and the location of electrons were also investigated

  12. 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.

  13. The balloon-borne electron telescope with scintillating fibers (BETS)

    CERN Document Server

    Torii, S; Tateyama, N; Yoshida, K; Ouchi, Y; Yamagami, T; Saitô, Y; Murakami, H; Kobayashi, T; Komori, Y; Kasahara, K; Yuda, T; Nishimura, J

    2000-01-01

    we describe a new detector system developed for high-altitude balloon flights to observe the cosmic-ray electrons above 10 GeV. The balloon borne electron telescope with Scintillating (BETS) fibers instrument is an imaging calorimeter which is capable of selecting electrons against the large background of protons. The calorimeter is composed of a sandwich of scintillating optical-fiber belts and lead plates with a combination of three plastic scintillators for the shower trigger. The total thickness of lead is 40 mm (~7.1 r.l.) and the number of fiber belts is nine. In each belt, alternating layers are oriented in orthogonal (x and y) directions. Two sets of an intensified CCD camera are adopted for read-out of the scintillating fibers in the x and y direction, respectively. The accelerator beam tests were carried out to study the performance of detector for electrons in 1996 and for protons in 1997 at CERN-SPS. The instrument was successfully flown aboard high-altitude balloon in 1997 and 1998. It is demonst...

  14. Optical and scintillation characteristics of Gd2YAl2Ga3O12:Ce and Lu2YAl2Ga3O12:Ce single crystals

    Science.gov (United States)

    Chewpraditkul, Warut; Sakthong, Ongsa; Pattanaboonmee, Nakarin; Chewpraditkul, Weerapong; Szczesniak, Tomasz; Swiderski, Lukasz; Moszynski, Marek; Kamada, Kei; Yoshikawa, Akira; Nikl, Martin

    2017-06-01

    The optical and scintillation characteristics of Gd2YAl2Ga3O12:Ce and Lu2YAl2Ga3O12:Ce single crystals are investigated. At 662 keV γ-rays, light yield (LY) of 37,900 ph/MeV and energy resolution of 7.0% obtained for Gd2YAl2Ga3O12:Ce are superior to those of 18,900 ph/MeV and 11.5% obtained for Lu2YAl2Ga3O12:Ce. Scintillation decays are measured using the time-correlated single photon counting technique. A fast component decay time of 45 ns with relative intensity of 88% obtained for Lu2YAl2Ga3O12:Ce is superior to that of 50 ns (65%) for Gd2YAl2Ga3O12:Ce. The linear attenuation coefficient at 662 keV γ-rays is also determined and discussed.

  15. LHCb Upgrade: Scintillating Fibre Tracker

    Science.gov (United States)

    Tobin, Mark

    2016-07-01

    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.

  16. LHCb Upgrade: Scintillating Fibre Tracker

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, Mark, E-mail: Mark.Tobin@epfl.ch

    2016-07-11

    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.

  17. 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.

  18. Methods of Fabricating Scintillators with Radioisotopes for Beta Battery Applications

    Science.gov (United States)

    Rensing, Noa M.; Squillante, Michael R.; Tieman, Timothy C.; Higgins, William; Shiriwadkar, Urmila

    2013-01-01

    Technology has been developed for a class of self-contained, long-duration power sources called beta batteries, which harvest the energy contained in the radioactive emissions from beta decay isotopes. The new battery is a significant improvement over the conventional phosphor/solar cell concept for converting this energy in three ways. First, the thin phosphor is replaced with a thick scintillator that is transparent to its own emissions. By using a scintillator sufficiently thick to completely stop all the beta particles, efficiency is greatly improved. Second, since the energy of the beta particles is absorbed in the scintillator, the semiconductor photodetector is shielded from radiation damage that presently limits the performance and lifetime of traditional phosphor converters. Finally, instead of a thin film of beta-emitting material, the isotopes are incorporated into the entire volume of the thick scintillator crystal allowing more activity to be included in the converter without self-absorption. There is no chemical difference between radioactive and stable strontium beta emitters such as Sr-90, so the beta emitter can be uniformly distributed throughout a strontium based scintillator crystal. When beta emitter material is applied as a foil or thin film to the surface of a solar cell or even to the surface of a scintillator, much of the radiation escapes due to the geometry, and some is absorbed within the layer itself, leading to inefficient harvesting of the energy. In contrast, if the emitting atoms are incorporated within the scintillator, the geometry allows for the capture and efficient conversion of the energy of particles emitted in any direction. Any gamma rays associated with secondary decays or Bremsstrahlung photons may also be absorbed within the scintillator, and converted to lower energy photons, which will in turn be captured by the photocell or photodiode. Some energy will be lost in this two-stage conversion process (high-energy particle

  19. Measurement of neutron dose with an organic liquid scintillator coupled with a spectrum weight function

    Energy Technology Data Exchange (ETDEWEB)

    Kim, E.; Endo, A.; Yamaguchi, Y.; Yoshizawa, M.; Nakamura, T.; Shiomi, T

    2002-07-01

    A dose evaluation method for neutrons in the energy range of a few MeV to 100 MeV has been developed using a spectrum weight function (G-function), which is applied to an organic liquid scintillator of 12.7 cm in diameter and 12.7 cm in length. The G-function that converts the pulse height spectrum of the scintillator into the ambient dose equivalent, H*(10), was calculated by an unfolding method using successive approximation of the response function of the scintillator and the ambient dose equivalent per unit neutron fluence (H*(10) conversion coefficients) of ICRP 74. To verify the response function of the scintillator and the value of H*(10) evaluated by the G-function, pulse height spectra of the scintillator were measured in some different neutron fields, which have continuous energy, monoenergetic and quasi-monoenergetic spectra. Values of H*(10) estimated using the G-function and pulse height spectra of the scintillator were compared with those calculated using neutron energy spectra. These doses agreed with each other. From the results, it was concluded that H*(10) can be evaluated directly from the pulse height spectrum of the scintillator by applying the G-function proposed in this study. (author)

  20. 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...

  1. Measurement of actinides in environmental samples by Photo-Electron Rejecting Alpha Liquid Scintillation

    Energy Technology Data Exchange (ETDEWEB)

    Cadieux, J.R. [Westinghouse Savannah River Co., Aiken, SC (United States); Clark, S. [Savannah River Ecology Lab., Univ. of Georgia (United States); Fjeld, R.A.; Reboul, S.; Sowder, A. [Clemson Univ., SC (United States). Dept. of Environmental Systems Engineering

    1994-05-01

    This work describes the adaptation of extractive scintillation with a Photo-Electron Rejecting Alpha Liquid Scintillation (PERALS) (ORDELA, Inc.) spectrometer to the analysis of actinides in environmental samples from the Savannah River Site (SRS). Environmental quality assurance standards and actual water samples were treated by one of two methods; either a two step direct extraction, or for more complex samples, pretreatment by an extraction chromatographic separation prior to measurement of the alpha activity by PERALS.

  2. Characterization of a new plastic scintillation material and comparison with liquid BC-501A scintillator

    OpenAIRE

    Poleshchuk, Oleksii

    2015-01-01

    In this work the capability of various scintillation materials to discriminate gamma rays and neutrons were studied. Also such basic properties of scintillators as light emission spectrum and light output were determined. The studied materials were BC-501A liquid scintillator and a plastic scintillator provided by CEA. An experimental setup consisting of detector shielding, analog and digital electronics and data acquisition system was built to study the neutron-gamma discrimination propertie...

  3. Scintillation in the Circinus Galaxy water megamasers

    CERN Document Server

    McCallum, J N

    2004-01-01

    We present observations of the 22 GHz water vapor megamasers in the Circinus galaxy made with the Tidbinbilla 70m telescope. These observations confirm the rapid variability seen earlier by Greenhill et al (1997). We show that this rapid variability can be explained by interstellar scintillation, based on what is now known of the interstellar scintillation seen in a significant number of flat spectrum AGN. The observed variability cannot be fully described by a simple model of either weak or diffractive scintillation.

  4. General optical scintillation in turbulent atmosphere

    Institute of Scientific and Technical Information of China (English)

    Ruizhong Rao

    2008-01-01

    A general expression of the scintillation index is proposed for optical wave propagating in turbulent atmosphere under arbitrary fluctuation conditions. The expression depends on extreme behaviors of the scintillation indices under both weak and strong fluctuations. The maximum scintillation index in the onset region and the corresponding Rytov index can be evaluated from the general expression. Plane and spherical waves in the cases of zero and non-zero turbulence inner scale are given as examples for illustration of the general behaviors of scintillation indices.

  5. High-symmetry organic scintillator systems

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. High-symmetry organic scintillator systems

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Patrick L.

    2017-09-05

    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.

  7. 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.

  8. A hadron calorimeter with scintillators parallel to the beam

    Science.gov (United States)

    Abramov, V.; Goncharov, P.; Gorin, A.; Gurzhiev, A.; Dyshkant, A.; Evdokimov, V.; Kolosov, V.; Korablev, A.; Korneev, Yu.; Kostritskii, A.; Krinitsyn, A.; Kryshkin, V.; Podstavkov, V.; Polyakov, V.; Shtannikov, A.; Tereschenko, S.; Turchanovich, L.; Zaichenko, A.

    1997-02-01

    A hadron calorimeter in which scintillators are arranged nearly parallel to the incident particle direction and light is collected by optical fibres with WLS, has been built. The iron absorber plates are of the tapered shape to fit a barrel structure of the collider geometry. The performance of the calorimeter studied with hadron beam is presented as a function of tilt angle without and with electromagnetic calorimeter in front of the hadron one.

  9. A hadron calorimeter with scintillators parallel to the beam

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, V.; Goncharov, P.; Gorin, A.; Gurzhiev, A.; Dyshkant, A.; Evdokimov, V.; Kolosov, V.; Korablev, A.; Korneev, Yu.; Kostritskii, A.; Krinitsyn, A.; Kryshkin, V.; Podstavkov, V.; Polyakov, V.; Shtannikov, A.; Tereschenko, S.; Turchanovich, L.; Zaichenko, A. [Institut Fiziki Vysokikh Ehnergij, Protvino (Russian Federation)

    1997-08-11

    A hadron calorimeter in which scintillators are arranged nearly parallel to the incident particle direction and light is collected by optical fibres with WLS, has been built. The iron absorber plates are of the tapered shape to fit a barrel structure of the collider geometry. The performance of the calorimeter studied with hadron beam is presented as a function of tilt angle without and with electromagnetic calorimeter in front of the hadron one. (orig.).

  10. Study of Scintillator thickness optimization of lens-coupled X-ray imaging detectors

    Science.gov (United States)

    Xie, H.; Du, G.; Deng, B.; Chen, R.; Xiao, T.

    2016-03-01

    Lens-coupled X-ray in-direct imaging detectors are very popular for high-resolution X-ray imaging at the third generation synchrotron radiation facilities. This imaging system consists of a scintilator producing a visible-light image of X-ray beam, a microscope objective, a mirror reflecting at 90° and a CCD camera. When the thickness of the scintillator is matched with the numerical aperture (NA) of the microscope objective, the image quality of experimental results will be improved obviously. This paper used an imaging system at BL13W beamline of Shanghai Synchrotron Radiation Facility (SSRF) to study the matching relation between the scintillator thickness and the NA of the microscope objective with a real sample. By use of the matching relation between the scintillator thickness and the NA of the microscope objective, the optimal imaging results have been obtained.

  11. 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...

  12. Photodetectors for scintillator proportionality measurement

    Energy Technology Data Exchange (ETDEWEB)

    Moses, William W. [Lawrence Berkeley National Laboratory (United States)], E-mail: wwmoses@lbl.gov; Choong, Woon-Seng [Lawrence Berkeley National Laboratory (United States); Hull, Giulia; Payne, Steve; Cherepy, Nerine; Valentine, John D. [Lawrence Livermore National Laboratory (United States)

    2009-10-21

    We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high ({approx}50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.

  13. Photodetectors for Scintillator Proportionality Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Moses, William W.; Choong, Woon-Seng; Hull, Giulia; Payne, Steve; Cherepy, Nerine; Valentine, J.D.

    2010-10-18

    We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high ({approx}50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.

  14. Performance and characteristics of a new scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Czirr, J.B. [Mission Support Incorporated, Provo, Utah (United States); MacGillivray, G.M. [Nray Services Inc., RP no. 1 Black Bay Road, Petawawa, Ont. K8H2W8 (Canada); MacGillivray, R.R. [Nray Services Inc., RP no. 1 Black Bay Road, Petawawa, Ont. K8H2W8 (Canada); Seddon, P.J. [Nray Services Inc., RP no. 1 Black Bay Road, Petawawa, Ont. K8H2W8 (Canada)

    1999-11-03

    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.

  15. 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.

  16. 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.

  17. Countering beam divergence effects with focused segmented scintillators for high DQE megavoltage active matrix imagers

    Science.gov (United States)

    Liu, Langechuan; Antonuk, Larry E.; Zhao, Qihua; El-Mohri, Youcef; Jiang, Hao

    2012-08-01

    The imaging performance of active matrix flat-panel imagers designed for megavoltage imaging (MV AMFPIs) is severely constrained by relatively low x-ray detection efficiency, which leads to a detective quantum efficiency (DQE) of only ∼1%. Previous theoretical and empirical studies by our group have demonstrated the potential for addressing this constraint through the utilization of thick, two-dimensional, segmented scintillators with optically isolated crystals. However, this strategy is constrained by the degradation of high-frequency DQE resulting from spatial resolution loss at locations away from the central beam axis due to oblique incidence of radiation. To address this challenge, segmented scintillators constructed so that the crystals are individually focused toward the radiation source are proposed and theoretically investigated. The study was performed using Monte Carlo simulations of radiation transport to examine the modulation transfer function and DQE of focused segmented scintillators with thicknesses ranging from 5 to 60 mm. The results demonstrate that, independent of scintillator thickness, the introduction of focusing largely restores spatial resolution and DQE performance otherwise lost in thick, unfocused segmented scintillators. For the case of a 60 mm thick BGO scintillator and at a location 20 cm off the central beam axis, use of focusing improves DQE by up to a factor of ∼130 at non-zero spatial frequencies. The results also indicate relatively robust tolerance of such scintillators to positional displacements, of up to 10 cm in the source-to-detector direction and 2 cm in the lateral direction, from their optimal focusing position, which could potentially enhance practical clinical use of focused segmented scintillators in MV AMFPIs.

  18. 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.

  19. Development of a wavelength-separated type scintillator with optical fiber (SOF) dosimeter to compensate for the Cerenkov radiation effect.

    Science.gov (United States)

    Ishikawa, Masayori; Nagase, Naomi; Matsuura, Taeko; Hiratsuka, Junichi; Suzuki, Ryusuke; Miyamoto, Naoki; Sutherland, Kenneth Lee; Fujita, Katsuhisa; Shirato, Hiroki

    2015-03-01

    The scintillator with optical fiber (SOF) dosimeter consists of a miniature scintillator mounted on the tip of an optical fiber. The scintillator of the current SOF dosimeter is a 1-mm diameter hemisphere. For a scintillation dosimeter coupled with an optical fiber, measurement accuracy is influenced by signals due to Cerenkov radiation in the optical fiber. We have implemented a spectral filtering technique for compensating for the Cerenkov radiation effect specifically for our plastic scintillator-based dosimeter, using a wavelength-separated counting method. A dichroic mirror was used for separating input light signals. Individual signal counting was performed for high- and low-wavelength light signals. To confirm the accuracy, measurements with various amounts of Cerenkov radiation were performed by changing the incident direction while keeping the Ir-192 source-to-dosimeter distance constant, resulting in a fluctuation of Optical fiber bending was also addressed; no bending effect was observed for our wavelength-separated SOF dosimeter.

  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.

    2017-06-01

    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.