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Sample records for high-bandwidth photon-counting detectors

  1. High-Bandwidth Photon-Counting Detectors with Enhanced Near-Infrared Response Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Long-range optical telecommunications (LROT) impose challenging requirements on detector array sensitivity at 1064nm and arrays timing bandwidth. Large photonic...

  2. 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

  3. 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.

  4. 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.

  5. 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.)

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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,...

  12. 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.

  13. 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

  14. 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...

  15. 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).

  16. 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...

  17. 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...

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. High-Bandwidth Photon-Counting Detectors with Enhanced Near-Infrared Response Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Laser optical communications offer the potential to dramatically increase the link bandwidth and decrease the emitter power in long-range space communications....

  4. 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...

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  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. 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.

  13. 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.

  14. 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.

  15. 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...

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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...

  3. 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.

  4. 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.

  5. 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)

  6. 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)

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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 (...

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

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

    Science.gov (United States)

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

    In recent years EAG has implemented a variety of high-resolution, large format, photon-counting MCP detectors in space instrumentation for satellite FUSE, GALEX, IMAGE, SOHO, HST-COS, rocket, and shuttle payloads. Our scheme of choice has been delay line readouts encoding photon event position centroids, by determination of the difference in arrival time of the event charge at the two ends of a distributed resistive-capacitive (RC) delay line. Our most commonly used delay line configuration is the cross delay line (XDL). In its simplest form the delay-line encoding electronics consists of a fast amplifier for each end of the delay line, followed by time-to-digital converters (TDC's). We have achieved resolutions of 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

  17. 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...

  18. 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

  19. 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

  20. 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...

  1. 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.

  2. 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

  3. 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.

  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. 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.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  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. 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)

  16. 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.

  17. 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.

  18. Two-dimensional photon counting imaging detector based on PCB delay line anode

    Science.gov (United States)

    Zhu, Bingli; Bai, Yonglin; Lei, Fanpu; Bai, Xiaohong; Wang, Bo; Qin, Junjun; Cao, Weiwei; Gou, Yongsheng

    2016-11-01

    Delay line anode detector has high spatial resolution and high count rate. It has been an important technical means for single photon imaging from near earth space to deep space. A two dimensional delay line anode is designed using multilayer circuit board technology. A complete set of PCB delay line anode single photon detection system is established. The spatial resolution of the detector is theoretically analyzed. Moreover, the signal transmission characteristic of PCB delay line and the dark count rate of the detector are tested. Theoretical analysis and experimental results show that the detector spatial resolution is about 100um and the overall dark count rate is 4counts/cm2 at 2.3KV.

  19. Fast Readout for Large Area Photon-Counting Infrared Detectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Many NASA space and Earth programs in the infrared range 1060-1550 nm are limited by the detector performance that require long exposure time due to their low...

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Characterization of Photon-Counting Detector Responsivity for Non-Linear Two-Photon Absorption Process

    Science.gov (United States)

    Sburlan, S. E.; Farr, W. H.

    2011-01-01

    Sub-band absorption at 1550 nm has been demonstrated and characterized on silicon Geiger mode detectors which normally would be expected to have no response at this wavelength. We compare responsivity measurements to singlephoton absorption for wavelengths slightly above the bandgap wavelength of silicon (approx. 1100 microns). One application for this low efficiency sub-band absorption is in deep space optical communication systems where it is desirable to track a 1030 nm uplink beacon on the same flight terminal detector array that monitors a 1550 nm downlink signal for pointingcontrol. The currently observed absorption at 1550 nm provides 60-70 dB of isolation compared to the response at 1064 nm, which is desirable to avoid saturation of the detector by scattered light from the downlink laser.

  7. Characterization of Photon-Counting Detector Responsivity for Non-Linear Two-Photon Absorption Process

    Science.gov (United States)

    Sburlan, S. E.; Farr, W. H.

    2011-01-01

    Sub-band absorption at 1550 nm has been demonstrated and characterized on silicon Geiger mode detectors which normally would be expected to have no response at this wavelength. We compare responsivity measurements to singlephoton absorption for wavelengths slightly above the bandgap wavelength of silicon (approx. 1100 microns). One application for this low efficiency sub-band absorption is in deep space optical communication systems where it is desirable to track a 1030 nm uplink beacon on the same flight terminal detector array that monitors a 1550 nm downlink signal for pointingcontrol. The currently observed absorption at 1550 nm provides 60-70 dB of isolation compared to the response at 1064 nm, which is desirable to avoid saturation of the detector by scattered light from the downlink laser.

  8. 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.

  9. Signal-to-noise ratio of Geiger-mode avalanche photodiode single-photon counting detectors

    Science.gov (United States)

    Kolb, Kimberly

    2014-08-01

    Geiger-mode avalanche photodiodes (GM-APDs) use the avalanche mechanism of semiconductors to amplify signals in individual pixels. With proper thresholding, a pixel will be either "on" (avalanching) or "off." This discrete detection scheme eliminates read noise, which makes these devices capable of counting single photons. Using these detectors for imaging applications requires a well-developed and comprehensive expression for the expected signal-to-noise ratio (SNR). This paper derives the expected SNR of a GM-APD detector in gated operation based on gate length, number of samples, signal flux, dark count rate, photon detection efficiency, and afterpulsing probability. To verify the theoretical results, carrier-level Monte Carlo simulation results are compared to the derived equations and found to be in good agreement.

  10. 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.

  11. 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.

  12. 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.

  13. Evaluation of a photon counting Medipix3RX CZT spectral x-ray detector

    Science.gov (United States)

    Jorgensen, Steven M.; Vercnocke, Andrew J.; Rundle, David S.; Butler, Philip H.; McCollough, Cynthia H.; Ritman, Erik L.

    2016-10-01

    We assessed the performance of a cadmium zinc telluride (CZT)-based Medipix3RX x-ray detector as a candidate for micro-computed tomography (micro-CT) imaging. This technology was developed at CERN for the Large Hadron Collider. It features an array of 128 by 128, 110 micrometer square pixels, each with eight simultaneous threshold counters, five of which utilize real-time charge summing, significantly reducing the charge sharing between contiguous pixels. Pixel response curves were created by imaging a range of x-ray intensities by varying x-ray tube current and by varying the exposure time with fixed x-ray current. Photon energy-related assessments were made by flooding the detector with the tin foil filtered emission of an I-125 radioisotope brachytherapy seed and sweeping the energy threshold of each of the four charge-summed counters of each pixel in 1 keV steps. Long term stability assessments were made by repeating exposures over the course of one hour. The high properly-functioning pixel yield (99%), long term stability (linear regression of whole-chip response over one hour of acquisitions: y = -0.0038x + 2284; standard deviation: 3.7 counts) and energy resolution (2.5 keV FWHM (single pixel), 3.7 keV FWHM across the full image) make this device suitable for spectral micro-CT. The charge summing performance effectively reduced the measurement corruption caused by charge sharing which, when unaccounted for, shifts the photon energy assignment to lower energies, degrading both count and energy accuracy. Effective charge summing greatly improves the potential for calibrated, energy-specific material decomposition and K edge difference imaging approaches.

  14. Evaluation of a photon counting Medipix3RX CZT spectral x-ray detector

    Science.gov (United States)

    Jorgensen, Steven M.; Vercnocke, Andrew J.; Rundle, David S.; Butler, Philip H.; McCollough, Cynthia H.; Ritman, Erik L.

    2016-01-01

    We assessed the performance of a cadmium zinc telluride (CZT)-based Medipix3RX x-ray detector as a candidate for micro-computed tomography (micro-CT) imaging. This technology was developed at CERN for the Large Hadron Collider. It features an array of 128 by 128, 110 micrometer square pixels, each with eight simultaneous threshold counters, five of which utilize real-time charge summing, significantly reducing the charge sharing between contiguous pixels. Pixel response curves were created by imaging a range of x-ray intensities by varying x-ray tube current and by varying the exposure time with fixed x-ray current. Photon energy-related assessments were made by flooding the detector with the tin foil filtered emission of an I-125 radioisotope brachytherapy seed and sweeping the energy threshold of each of the four charge-summed counters of each pixel in 1 keV steps. Long term stability assessments were made by repeating exposures over the course of one hour. The high properly-functioning pixel yield (99%), long term stability (linear regression of whole-chip response over one hour of acquisitions: y = −0.0038x + 2284; standard deviation: 3.7 counts) and energy resolution (2.5 keV FWHM (single pixel), 3.7 keV FWHM across the full image) make this device suitable for spectral micro-CT. The charge summing performance effectively reduced the measurement corruption caused by charge sharing which, when unaccounted for, shifts the photon energy assignment to lower energies, degrading both count and energy accuracy. Effective charge summing greatly improves the potential for calibrated, energy-specific material decomposition and K edge difference imaging approaches.

  15. 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.)

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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).

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

    Science.gov (United States)

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

    2013-01-01

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

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  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. 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.

  12. Picosecond time-resolved laser pump/X-ray probe experiments using a gated single-photon-counting area detector

    DEFF Research Database (Denmark)

    Ejdrup, T.; Lemke, H.T.; Haldrup, Martin Kristoffer

    2009-01-01

    . The capability of the gated PILATUS detector to selectively detect the signal from a given X-ray pulse in 24 bunch mode at the APS storage ring is demonstrated. A test experiment performed on polycrystalline organic thin films of [alpha]-perylene illustrates the possibility of reaching an X-ray pulse duration......The recent developments in X-ray detectors have opened new possibilities in the area of time-resolved pump/probe X-ray experiments; this article presents the novel use of a PILATUS detector to achieve X-ray pulse duration limited time-resolution at the Advanced Photon Source (APS), USA...... limited time-resolution of 60 ps using the gated PILATUS detector. This is the first demonstration of X-ray pulse duration limited data recorded using an area detector without the use of a mechanical chopper array at the beamline....

  13. Photon counts statistics of squeezed and multi-mode thermal states of light on multiplexed on-off detectors

    CERN Document Server

    Chrapkiewicz, Radosław

    2015-01-01

    Photon number resolving detectors can be highly useful for studying the statistics of multi-photon quantum states of light. In this work we study the counts statistics of different states of light measured on multiplexed on-off detectors. We put special emphasis on artificial nonclassical features of the statistics obtained. We show new ways to derive analytical formulas for counts statistics and their moments. Using our approach we are the first to derive statistics moments for multi-mode thermal states measured on multiplexed on-off detectors. We use them to determine empirical Mandel parameters and recently proposed subbinomial parameters suitable for tests of nonclassicality of the measured states. Additionally, we investigate subpoissonian and superbunching properties of the two-mode squeezed state measured on a pair of multiplexed detectors and we present results of the Fano factor and second-order correlation function for these states.

  14. 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.

  15. X-ray photon-counting detector based on a micro-channel plate for pulsar navigation

    Institute of Scientific and Technical Information of China (English)

    Baomei Chen; Baosheng Zhao; Huijun Hu; Qiurong Yan; Lizhi Sheng

    2011-01-01

    The pulse time of arrival (TOA) is a determining parameter for accurate timing and positioning in X-ray pulsar navigation. The pulse TOA can be calculated by comparing the measured arrival time with the predicted arrival time of the X-ray pulse for pulsar. In this study, in order to research the measurement of pulse arrival time, an experimental system is set up. The experimental system comprises a simulator of the X-ray pulsar, an X-ray detector, a time-measurement system, and a data-processing system. An X-ray detector base is proposed on the basis of the micro-channel plate (MCP), which is sensitive to soft X-ray in the 1-10 keV band. The MCP-based detector, the structure and principle of the experimental system, and results of the pulse profile are described in detail. In addition, a discussion of the effects of different X-ray pulse periods and the quantum efficiency of the detector on pulse-profile signal-to-noise ratio (SNR) is presented. Experimental results reveal that the SNR of the measured pulse profile becomes enhanced as the quantum efficiency of the detector increases. The SNR of the pulse profile is higher when the period of the pulse is smaller at the same integral.%@@ The pulse time of arrival (TOA) is a determining parameter for accurate timing and positioning in X-ray pulsar navigation.The pulse TOA can be calculated by comparing the measured arrival time with the predicted arrival time of the X-ray pulse for pulsar.In this study, in order to research the measurement of pulse arrival time, an experimental system is set up.The experimental system comprises a simulator of the X-ray pulsar, an X-ray detector, a time-measurement system, and a data-processing system.An X-ray detector base is proposed on the basis of the micro-channel plate (MCP), which is sensitive to soft X-ray in the 1-10 keV band.The MCP-based detector, the structure and principle of the experimental system,and results of the pulse profile are described in detail.In addition, a

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  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. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. 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.

  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. 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

  13. 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

  14. 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

  15. 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...

  16. 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...

  17. 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...

  18. 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.

  19. Amplitude distributions of dark counts and photon counts in NbN superconducting single-photon detectors integrated with the HEMT readout

    Science.gov (United States)

    Kitaygorsky, J.; Słysz, W.; Shouten, R.; Dorenbos, S.; Reiger, E.; Zwiller, V.; Sobolewski, Roman

    2017-01-01

    We present a new operation regime of NbN superconducting single-photon detectors (SSPDs) by integrating them with a low-noise cryogenic high-electron-mobility transistor and a high-load resistor. The integrated sensors are designed to get a better understanding of the origin of dark counts triggered by the detector, as our scheme allows us to distinguish the origin of dark pulses from the actual photon pulses in SSPDs. The presented approach is based on a statistical analysis of amplitude distributions of recorded trains of the SSPD photoresponse transients. It also enables to obtain information on energy of the incident photons, as well as demonstrates some photon-number-resolving capability of meander-type SSPDs.

  20. Investigation of quad-energy high-rate photon counting for X-ray computed tomography using a cadmium telluride detector.

    Science.gov (United States)

    Matsukiyo, Hiroshi; Sato, Eiichi; Oda, Yasuyuki; Yamaguchi, Satoshi; Sato, Yuichi; Hagiwara, Osahiko; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya

    2017-09-10

    To obtain four kinds of tomograms at four different X-ray energy ranges simultaneously, we have constructed a quad-energy (QE) X-ray photon counter with a cadmium telluride (CdTe) detector and four sets of comparators and microcomputers (MCs). X-ray photons are detected using the CdTe detector, and the event pulses produced using amplifiers are sent to four comparators simultaneously to regulate four threshold energies of 20, 33, 50 and 65keV. Using this counter, the energy ranges are 20-33, 33-50, 50-65 and 65-100keV; the maximum energy corresponds to the tube voltage. We performed QE computed tomography (QE-CT) at a tube voltage of 100kV. Using a 0.5-mm-diam lead pinhole, four tomograms were obtained simultaneously at four energy ranges. K-edge CT using iodine and gadolinium media was carried out utilizing two energy ranges of 33-50 and 50-65keV, respectively. At a tube voltage of 100kV and a current of 60 μA, the count rate was 15.2 kilocounts per second (kcps), and the minimum count rates after penetrating objects in QE-CT were regulated to approximately 2 kcps by the tube current. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Investigation of dual-energy X-ray photon counting using a cadmium telluride detector with dual-energy selection electronics

    Science.gov (United States)

    Sato, Eiichi; Kosuge, Yoshiyuki; Yamanome, Hayato; Mikata, Akiko; Miura, Tatsuya; Oda, Yasuyuki; Ishii, Tomotaka; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Watanabe, Manabu; Kusachi, Shinya

    2017-01-01

    To obtain two kinds of tomograms at two different X-ray energy ranges simultaneously, we have developed a dual-energy X-ray photon counter with a cadmium telluride (CdTe) detector and two energy-selecting devices (ESDs). The ESD consists of two comparators and a microcomputer (MC). X-ray photons are detected using the CdTe detector, and the event pulses from a shaping amplifier are sent to two ESDs simultaneously to determine two energy ranges. X-ray photons in the two ranges are counted using the MCs, and the logical pulses from the MCs are input to frequency-to-voltage converters (FVCs). The outputs from the two FVCs are input to a personal computer through an analog-to-digital converter to carry out dual-energy computed tomography. The tube voltage and current were 80 kV and 8.5 μA, respectively. Two tomograms were obtained simultaneously with two energy ranges. K-edge CT using iodine and gadolinium media was carried out utilizing two energy ranges of 33-45 and 50-65 keV, respectively. The maximum count rate was 6.8 kilocounts per second with energies ranging from 10 to 80 keV, and the exposure time for tomography was 9.8 min.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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。

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  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. 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.

  5. 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...

  6. 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.

  7. High-Bandwidth Hybrid Sensor (HYSENS) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — ATA has demonstrated the primary innovation of combining a precision MEMS gyro (BAE SiRRS01) with a high bandwidth angular rate sensor, ATA's ARS-14 resulting in a...

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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%.

  14. 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.

  15. 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.

  16. 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.

  17. 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...

  18. 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.

  19. 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

  20. Modulator-Based, High Bandwidth Optical Links for HEP Experiments

    CERN Document Server

    Underwood, D G; Fernando, W S; Stanek, R W

    2012-01-01

    As a concern with the reliability, bandwidth and mass of future optical links in LHC experiments, we are investigating CW lasers and light modulators as an alternative to VCSELs. These links will be particularly useful if they utilize light modulators which are very small, low power, high bandwidth, and are very radiation hard. We have constructed a test system with 3 such links, each operating at 10 Gb/s. We present the quality of these links (jitter, rise and fall time, BER) and eye mask margins (10GbE) for 3 different types of modulators: LiNbO3-based, InP-based, and Si-based. We present the results of radiation hardness measurements with up to ~1012 protons/cm2 and ~65 krad total ionizing dose (TID), confirming no single event effects (SEE) at 10 Gb/s with either of the 3 types of modulators. These optical links will be an integral part of intelligent tracking systems at various scales from coupled sensors through intra-module and off detector communication. We have used a Si-based photonic transceiver to...

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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...

  12. 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...

  13. 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.

  14. 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.

  15. 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.

  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. 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...

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. 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.

  5. 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.)

  6. 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.

  7. Soft X-ray and extreme ultraviolet photon-counting imaging detector with curved surface micro-channel plate and induced charge position-sensitive anode%使用曲面微通道板和感应电荷位置灵敏阳极的软 X 射线-极紫外光子计数成像探测器研究

    Institute of Scientific and Technical Information of China (English)

    尼启良

    2015-01-01

    本项目对我国空间探测的极紫外( EUV)波段大视场相机所需求的球面光子计数成像探测器的关键技术进行了研究。首先,建立了光阴极材料次级电子产出模型,利用该模型计算了软X射线-EUV波段常用的光电阴极材料—碱卤化物的次级电子产出,分析了微通道板( MCP)的次级电子产出。建立了测量MCP量子探测效率的装置,并推导出MCP量子探测效率的计算公式,测量了MCP在软X射线-EUV波段的量子效率以及MCP量子效率随掠入射角的变化。其次,建立了球面实芯微通道板的制备装置,利用高温热成型方法制备出曲率半径为150 mm球面MCP,利用光刻技术制备出有效直径为48 mm的楔条形感应电荷位置灵敏阳极,在此基础上集成了一套使用球面MCP和感应电荷位置灵敏阳极的两维光子计数成像探测器。再次,研制出包括快速前端模拟电路与后续数字电路的成像读出电路,编制了能矫正图像畸变的图像实时采集和处理软件。最后,建立了MCP探测器空间分辨率、图像线性的检测装置,对研制出的探测器性能进行了检测,检测结果表明:探测器的各项技术指标完全满足要求。%The research on key techniques of wide field extreme ultraviolet ( EUV ) spherical micro-channel plate( MCP) photon-counting imaging detector which will be used in space probe in China have been done. Firstly, the secondary electron yield model of photocathode material was built, and the secondary yield of alka-li halide and MCP in soft X-ray and EUV band were calculated using the model.The measurement equipment of MCP′s quantum detection efficiency also was set up.The calculated fomula of MCP′s quantum efficiency was introduced, and MCP′s quantum efficiency vs.wavelength and incidence angle in soft X-ray and EUV re-gion were measured.secondly, the instrument of solid core spherical MCP fabrication was

  8. 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.

  9. Pixel detectors

    CERN Document Server

    Passmore, M S

    2001-01-01

    positions on the detector. The loss of secondary electrons follows the profile of the detector and increases with higher energy ions. studies of the spatial resolution predict a value of 5.3 lp/mm. The image noise in photon counting systems is investigated theoretically and experimentally and is shown to be given by Poisson statistics. The rate capability of the LAD1 was measured to be 250 kHz per pixel. Theoretical and experimental studies of the difference in contrast for ideal charge integrating and photon counting imaging systems were carried out. It is shown that the contrast differs and that for the conventional definition (contrast = (background - signal)/background) the photon counting device will, in some cases, always give a better contrast than the integrating system. Simulations in MEDICI are combined with analytical calculations to investigate charge collection efficiencies (CCE) in semiconductor detectors. Different pixel sizes and biasing conditions are considered. The results show charge shari...

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Network Bandwidth Utilization Forecast Model on High Bandwidth Network

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Wucherl; Sim, Alex

    2014-07-07

    With the increasing number of geographically distributed scientific collaborations and the scale of the data size growth, it has become more challenging for users to achieve the best possible network performance on a shared network. We have developed a forecast model to predict expected bandwidth utilization for high-bandwidth wide area network. The forecast model can improve the efficiency of resource utilization and scheduling data movements on high-bandwidth network to accommodate ever increasing data volume for large-scale scientific data applications. Univariate model is developed with STL and ARIMA on SNMP path utilization data. Compared with traditional approach such as Box-Jenkins methodology, our forecast model reduces computation time by 83.2percent. It also shows resilience against abrupt network usage change. The accuracy of the forecast model is within the standard deviation of the monitored measurements.

  17. 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.

  18. 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

  19. Imaging by photon counting with 256 x 256 pixel matrix

    CERN Document Server

    Tlustos, Lukas; Heijne, Erik H M; Llopart-Cudie, Xavier

    2004-01-01

    Using 0.25 mum 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 256 multiplied by 256 square 55mum 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 similar to 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 3 multiplied by 10exp10 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 similar to 300 mus 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 t...

  20. 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.

  1. 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.

  2. 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.

  3. VISA IB Ultra-High Bandwidth, High Gain SASE FEL

    CERN Document Server

    Andonian, Gerard; Murokh, Alex; Pellegrini, Claudio; Reiche, Sven; Rosenzweig, J B; Travish, Gil

    2004-01-01

    The results of a high energy-spread SASE FEL experiment, the intermediary experiment linking the VISA I and VISA II projects, are presented. A highly chirped beam (~1.7%) was transported without correction of longitudinal aberrations in the ATF dogleg, and injected into the VISA undulator. The output FEL radiation displayed an uncharacteristicly large bandwidth (~11%) with extremely stable lasing and measured energy of about 2 microJoules. Start-to-end simulations reproduce key features of the measured results and provide an insight into the mechanisms giving rise to such a high bandwidth. These analyses are described as they relate to important considerations for the VISA II experiment.

  4. 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

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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...

  11. 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...

  12. 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.

  13. 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...

  14. 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.

  15. 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.

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

    Science.gov (United States)

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

    2014-01-01

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

  17. Simple High-Bandwidth Sideband Locking with Heterodyne Readout

    CERN Document Server

    Reinhardt, Christoph; Sankey, Jack C

    2016-01-01

    We present a robust sideband laser locking technique that is ideally suited for applications requiring low probe power and heterodyne readout. By feeding back to a high-bandwidth voltage controlled oscillator, we lock a first-order phase-modulation sideband to a table-top high-finesse Fabry-Perot cavity, achieving a feedback bandwidth of 3.5 MHz with a single integrator, limited fundamentally by the signal delay. The directly measured transfer function of the closed feedback loop agrees with a model assuming ideal system components, and from this we suggest a modified design that should realistically achieve a bandwidth exceeding 6 MHz with a near-causally limited feedback gain of $4\\times 10^7$ at 1 kHz. The off-resonance optical carrier is used for alignment-free heterodyne readout, alleviating the need for a second laser or additional optical modulators.

  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

    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.

  19. Engineering the CernVM-Filesystem as a High Bandwidth Distributed Filesystem for Auxiliary Physics Data

    Science.gov (United States)

    Dykstra, D.; Bockelman, B.; Blomer, J.; Herner, K.; Levshina, T.; Slyz, M.

    2015-12-01

    A common use pattern in the computing models of particle physics experiments is running many distributed applications that read from a shared set of data files. We refer to this data is auxiliary data, to distinguish it from (a) event data from the detector (which tends to be different for every job), and (b) conditions data about the detector (which tends to be the same for each job in a batch of jobs). Relatively speaking, conditions data also tends to be relatively small per job where both event data and auxiliary data are larger per job. Unlike event data, auxiliary data comes from a limited working set of shared files. Since there is spatial locality of the auxiliary data access, the use case appears to be identical to that of the CernVM- Filesystem (CVMFS). However, we show that distributing auxiliary data through CVMFS causes the existing CVMFS infrastructure to perform poorly. We utilize a CVMFS client feature called "alien cache" to cache data on existing local high-bandwidth data servers that were engineered for storing event data. This cache is shared between the worker nodes at a site and replaces caching CVMFS files on both the worker node local disks and on the site's local squids. We have tested this alien cache with the dCache NFSv4.1 interface, Lustre, and the Hadoop Distributed File System (HDFS) FUSE interface, and measured performance. In addition, we use high-bandwidth data servers at central sites to perform the CVMFS Stratum 1 function instead of the low-bandwidth web servers deployed for the CVMFS software distribution function. We have tested this using the dCache HTTP interface. As a result, we have a design for an end-to-end high-bandwidth distributed caching read-only filesystem, using existing client software already widely deployed to grid worker nodes and existing file servers already widely installed at grid sites. Files are published in a central place and are soon available on demand throughout the grid and cached locally on the

  20. Engineering the CernVM-Filesystem as a High Bandwidth Distributed Filesystem for Auxiliary Physics Data

    Energy Technology Data Exchange (ETDEWEB)

    Dykstra, D. [Fermilab; Bockelman, B. [Nebraska U.; Blomer, J. [CERN; Herner, K. [Fermilab; Levshina, T. [Fermilab; Slyz, M. [Fermilab

    2015-12-23

    A common use pattern in the computing models of particle physics experiments is running many distributed applications that read from a shared set of data files. We refer to this data is auxiliary data, to distinguish it from (a) event data from the detector (which tends to be different for every job), and (b) conditions data about the detector (which tends to be the same for each job in a batch of jobs). Relatively speaking, conditions data also tends to be relatively small per job where both event data and auxiliary data are larger per job. Unlike event data, auxiliary data comes from a limited working set of shared files. Since there is spatial locality of the auxiliary data access, the use case appears to be identical to that of the CernVM- Filesystem (CVMFS). However, we show that distributing auxiliary data through CVMFS causes the existing CVMFS infrastructure to perform poorly. We utilize a CVMFS client feature called 'alien cache' to cache data on existing local high-bandwidth data servers that were engineered for storing event data. This cache is shared between the worker nodes at a site and replaces caching CVMFS files on both the worker node local disks and on the site's local squids. We have tested this alien cache with the dCache NFSv4.1 interface, Lustre, and the Hadoop Distributed File System (HDFS) FUSE interface, and measured performance. In addition, we use high-bandwidth data servers at central sites to perform the CVMFS Stratum 1 function instead of the low-bandwidth web servers deployed for the CVMFS software distribution function. We have tested this using the dCache HTTP interface. As a result, we have a design for an end-to-end high-bandwidth distributed caching read-only filesystem, using existing client software already widely deployed to grid worker nodes and existing file servers already widely installed at grid sites. Files are published in a central place and are soon available on demand throughout the grid and cached

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Managing high-bandwidth real-time data storage

    Energy Technology Data Exchange (ETDEWEB)

    Bigelow, David D. [Los Alamos National Laboratory; Brandt, Scott A [Los Alamos National Laboratory; Bent, John M [Los Alamos National Laboratory; Chen, Hsing-Bung [Los Alamos National Laboratory

    2009-09-23

    There exist certain systems which generate real-time data at high bandwidth, but do not necessarily require the long-term retention of that data in normal conditions. In some cases, the data may not actually be useful, and in others, there may be too much data to permanently retain in long-term storage whether it is useful or not. However, certain portions of the data may be identified as being vitally important from time to time, and must therefore be retained for further analysis or permanent storage without interrupting the ongoing collection of new data. We have developed a system, Mahanaxar, intended to address this problem. It provides quality of service guarantees for incoming real-time data streams and simultaneous access to already-recorded data on a best-effort basis utilizing any spare bandwidth. It has built in mechanisms for reliability and indexing, can scale upwards to meet increasing bandwidth requirements, and handles both small and large data elements equally well. We will show that a prototype version of this system provides better performance than a flat file (traditional filesystem) based version, particularly with regard to quality of service guarantees and hard real-time requirements.

  8. Ultra-high bandwidth quantum secured data transmission

    Science.gov (United States)

    Dynes, James F.; Tam, Winci W.-S.; Plews, Alan; Fröhlich, Bernd; Sharpe, Andrew W.; Lucamarini, Marco; Yuan, Zhiliang; Radig, Christian; Straw, Andrew; Edwards, Tim; Shields, Andrew J.

    2016-10-01

    Quantum key distribution (QKD) provides an attractive means for securing communications in optical fibre networks. However, deployment of the technology has been hampered by the frequent need for dedicated dark fibres to segregate the very weak quantum signals from conventional traffic. Up until now the coexistence of QKD with data has been limited to bandwidths that are orders of magnitude below those commonly employed in fibre optic communication networks. Using an optimised wavelength divisional multiplexing scheme, we transport QKD and the prevalent 100 Gb/s data format in the forward direction over the same fibre for the first time. We show a full quantum encryption system operating with a bandwidth of 200 Gb/s over a 100 km fibre. Exploring the ultimate limits of the technology by experimental measurements of the Raman noise, we demonstrate it is feasible to combine QKD with 10 Tb/s of data over a 50 km link. These results suggest it will be possible to integrate QKD and other quantum photonic technologies into high bandwidth data communication infrastructures, thereby allowing their widespread deployment.

  9. Ultra-high bandwidth quantum secured data transmission

    Science.gov (United States)

    Dynes, James F.; Tam, Winci W-S.; Plews, Alan; Fröhlich, Bernd; Sharpe, Andrew W.; Lucamarini, Marco; Yuan, Zhiliang; Radig, Christian; Straw, Andrew; Edwards, Tim; Shields, Andrew J.

    2016-01-01

    Quantum key distribution (QKD) provides an attractive means for securing communications in optical fibre networks. However, deployment of the technology has been hampered by the frequent need for dedicated dark fibres to segregate the very weak quantum signals from conventional traffic. Up until now the coexistence of QKD with data has been limited to bandwidths that are orders of magnitude below those commonly employed in fibre optic communication networks. Using an optimised wavelength divisional multiplexing scheme, we transport QKD and the prevalent 100 Gb/s data format in the forward direction over the same fibre for the first time. We show a full quantum encryption system operating with a bandwidth of 200 Gb/s over a 100 km fibre. Exploring the ultimate limits of the technology by experimental measurements of the Raman noise, we demonstrate it is feasible to combine QKD with 10 Tb/s of data over a 50 km link. These results suggest it will be possible to integrate QKD and other quantum photonic technologies into high bandwidth data communication infrastructures, thereby allowing their widespread deployment. PMID:27734921

  10. 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

  11. Very High Gain and Low Noise Near Infrared Single Photon Counting Detectors and Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Amplification Technologies Inc ("ATI") proposes to develop the enabling material and device technology for the design of ultra low noise, high gain and low...

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

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will focus on fabricating and optimizing a photodetector that utilizes the emerging technology of internal discrete amplification to create...

  13. High Performance Negative Feedback Near Infrared Single Photon Counting Detectors & Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Amplification Technologies Inc ("ATI") proposes to develop the enabling material and device technology for the design of ultra low noise, high gain and...

  14. High Performance Negative Feedback Near Infrared Single Photon Counting Detectors & Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Amplification Technologies Inc ("ATI") proposes to develop the enabling material and device technology for the design of ultra low noise, high gain and high speed...

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Extremelly High Bandwidth Rad Hard Data Acquisition System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advancements in sensors/detectors are needed to support future NASA mission concepts including polarimetry, large format imaging arrays, and high-sensitivity...

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  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. 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.

  19. 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.

  20. 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.

  1. 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).

  2. 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.

  3. Ultra-low Noise, High Bandwidth, 1550nm HgCdTe APD Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To meet the demands of future high-capacity free space optical communications links, a high bandwidth, near infrared (NIR), single photon sensitive optoelectronic...

  4. 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.

  5. 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.

  6. 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 ...

  7. 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.

  8. 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).

  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. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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).

  18. 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.

  19. 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.

  20. 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 ...

  1. 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.

  2. Level-1 Data Driver Card - A high bandwidth radiation tolerant aggregator board for detectors

    CERN Document Server

    Gkountoumis, Panagiotis; The ATLAS collaboration

    2017-01-01

    The Level-1 Data Driver Card (L1DDC) was designed for the needs of the future upgrades of the innermost stations of the ATLAS end-cap muon spectrometer. The L1DDC is a high speed aggregator board capable of communicating with multiple front-end electronic boards. It collects the Level-1 data along with monitoring data and transmits them to a network interface through bidirectional and/or unidirectional fiber links at 4.8 Gbps each. In addition, the L1DDC board distributes trigger, time and configuration data coming from the network interface to the front-end boards. The L1DDC is fully compatible with the Phase II upgrade where the trigger rate is expected to reach the 1 MHz. Three different types of L1DDC boards will be fabricated handling up to 10.080 Gbps of user data. It consist of custom made radiation tolerant ASICs: the GigaBit Transceiver (GBTx), the FEAST DC-DC converter, the Slow Control Adapter (SCA), and the Versatile Tranceivers (VTRX) and transmitters (VTTX). The overall scheme of the data acquis...

  3. Development of HEROICs: High-Sensitivity, High-Dynamic Range Detector Systems for Ultraviolet Astronomy Project

    Data.gov (United States)

    National Aeronautics and Space Administration — "We propose a four-year program for the fabrication and characterization of high dynamic range, low background photon counting detectors that will support the next...

  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. 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

  6. 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

  7. 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.

  8. High Bandwidth Rotary Fast Tool Servos and a Hybrid Rotary/Linear Electromagnetic Actuator

    Energy Technology Data Exchange (ETDEWEB)

    Montesanti, Richard Clement [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2005-09-01

    This thesis describes the development of two high bandwidth short-stroke rotary fast tool servos and the hybrid rotary/linear electromagnetic actuator developed for one of them. Design insights, trade-o® methodologies, and analytical tools are developed for precision mechanical systems, power and signal electronic systems, control systems, normal-stress electromagnetic actuators, and the dynamics of the combined systems.

  9. 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

  10. 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.

  11. 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.

  12. HgCdTe Infrared Avalanche Photodiode Single Photon Detector Arrays for the LIST and Other Decadal Missions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop a HgCdTe avalanche photodiode (APD)  SWIR/IR linear mode photon counting (LMPC) array detector system in support of the LIST lidar. Provide a new type...

  13. Use of Feedback to Maximize Photon Count Rate in XRF Spectroscopy

    CERN Document Server

    Lucas, Benjamin A

    2016-01-01

    The effective bandwidth of an energy dispersive x-ray fluorescence spectroscopy system is limited by the timing of incident photons. When multiple photons strike the detector within the processing time of the detector photon pile-up occurs and the signal received by the detector during this interval must be ignored. In conventional ED-XRF systems the probability of a photon being incident upon the detector is uniform over time, and thus pile-up follows Poisson statistics. In this paper we present a mathematical treatment of the relationship between photon timing statistics and the count rate of an XRF system. We show that it is possible to increase the maximum count rates by applying feedback from the detector to the x-ray source to alter the timing statistics of photon emission. Monte-Carlo simulations, show that this technique can increase the maximum count rate of an XRF spectroscopy system by a factor of 2.94 under certain circumstances.

  14. 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.

  15. 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.

  16. Bullet: high bandwidth data dissemination using an overlay mesh

    OpenAIRE

    Kostic, D.; Rodriguez, A.; J. Albrecht; Vahdat, A.

    2003-01-01

    In recent years, overlay networks have become an effective alternative to IP multicast for efficient point to multipoint communication across the Internet. Typically, nodes self-organize with the goal of forming an efficient overlay tree, one that meets performance targets without placing undue burden on the underlying network. In this paper, we target high-bandwidth data distribution from a single source to a large number of receivers. Applications include large-file transfers and real-time ...

  17. Knee implant imaging at 3 Tesla using high-bandwidth radiofrequency pulses.

    Science.gov (United States)

    Bachschmidt, Theresa J; Sutter, Reto; Jakob, Peter M; Pfirrmann, Christian W A; Nittka, Mathias

    2015-06-01

    To investigate the impact of high-bandwidth radiofrequency (RF) pulses used in turbo spin echo (TSE) sequences or combined with slice encoding for metal artifact correction (SEMAC) on artifact reduction at 3 Tesla in the knee in the presence of metal. Local transmit/receive coils feature increased maximum B1 amplitude, reduced SAR exposition and thus enable the application of high-bandwidth RF pulses. Susceptibility-induced through-plane distortion scales inversely with the RF bandwidth and the view angle, hence blurring, increases for higher RF bandwidths, when SEMAC is used. These effects were assessed for a phantom containing a total knee arthroplasty. TSE and SEMAC sequences with conventional and high RF bandwidths and different contrasts were tested on eight patients with different types of implants. To realize scan times of 7 to 9 min, SEMAC was always applied with eight slice-encoding steps and distortion was rated by two radiologists. A local transmit/receive knee coil enables the use of an RF bandwidth of 4 kHz compared with 850 Hz in conventional sequences. Phantom scans confirm the relation of RF bandwidth and through-plane distortion, which can be reduced up to 79%, and demonstrate the increased blurring for high-bandwidth RF pulses. In average, artifacts in this RF mode are rated hardly visible for patients with joint arthroplasties, when eight SEMAC slice-encoding steps are applied, and for patients with titanium fixtures, when TSE is used. The application of high-bandwidth RF pulses by local transmit coils substantially reduces through-plane distortion artifacts at 3 Tesla. © 2014 Wiley Periodicals, Inc.

  18. 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.

  19. Automatic high-bandwidth calibration and reconstruction of arbitrarily sampled parallel MRI.

    Directory of Open Access Journals (Sweden)

    Jan Aelterman

    Full Text Available Today, many MRI reconstruction techniques exist for undersampled MRI data. Regularization-based techniques inspired by compressed sensing allow for the reconstruction of undersampled data that would lead to an ill-posed reconstruction problem. Parallel imaging enables the reconstruction of MRI images from undersampled multi-coil data that leads to a well-posed reconstruction problem. Autocalibrating pMRI techniques encompass pMRI techniques where no explicit knowledge of the coil sensivities is required. A first purpose of this paper is to derive a novel autocalibration approach for pMRI that allows for the estimation and use of smooth, but high-bandwidth coil profiles instead of a compactly supported kernel. These high-bandwidth models adhere more accurately to the physics of an antenna system. The second purpose of this paper is to demonstrate the feasibility of a parameter-free reconstruction algorithm that combines autocalibrating pMRI and compressed sensing. Therefore, we present several techniques for automatic parameter estimation in MRI reconstruction. Experiments show that a higher reconstruction accuracy can be had using high-bandwidth coil models and that the automatic parameter choices yield an acceptable result.

  20. Continuous-wave near-photon counting spectral imaging detector in the mid-infrared by upconversion

    DEFF Research Database (Denmark)

    Dam, Jeppe Seidelin; Tidemand-Lichtenberg, Peter; Pedersen, Christian

    2013-01-01

    Low noise upconversion of IR images by three-wave mixing, can be performed with high efficiency when mixing the object radiation with a powerful laser field inside a highly non-linear crystal such as periodically poled Lithium Niobate. Since IR cameras are expensive and have high levels of intrin......Low noise upconversion of IR images by three-wave mixing, can be performed with high efficiency when mixing the object radiation with a powerful laser field inside a highly non-linear crystal such as periodically poled Lithium Niobate. Since IR cameras are expensive and have high levels...... high-end IR cameras have read noise of hundreds of electrons. The dark noise for infrared cameras based on semiconductor materials is also substantially higher than for silicon cameras, typical values being millions of electrons per pixel per second for cryogenically cooled cameras whereas peltier...... cooled CCD cameras have dark noise measured in fractions of electrons per pixel per second. An ideal solution thus suggest the combination of an efficient low noise image wavelength conversion system combined with low noise silicon based cameras for low noise imaging in the IR region. We discuss image...

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Designing and implementing Multibeam Smart Antennas for high bandwidth UAV communications using FPGAs

    Science.gov (United States)

    Porcello, J. C.

    Requirements for high bandwidth UAV communications are often necessary in order to move large amounts of mission information to/from Users in real-time. The focus of this paper is antenna beamforming for point-to-point, high bandwidth UAV communications in order to optimize transmit and receive power and support high data throughput communications. Specifically, this paper looks at the design and implementation of Multibeam Smart Antennas to implement antenna beamforming in an aerospace communications environment. The Smart Antenna is contrasted against Fast Fourier Transform (FFT) based beamforming in order to quantify the increase in both computational load and FPGA resources required for multibeam adaptive signal processing in the Smart Antenna. The paper begins with an overall discussion of Smart Antenna design and general beamforming issues in high bandwidth communications. Important design considerations such as processing complexity in a constrained Size, Weight and Power (SWaP) environment are discussed. The focus of the paper is with respect to design and implementation of digital beamforming wideband communications waveforms using FPGAs. A Multibeam Time Delay element is introduced based on Lagrange Interpolation. Design data for Multibeam Smart Antennas in FPGAs is provided in the paper as well as reference circuits for implementation. Finally, an example Multibeam Smart Antenna design is provided based on a Xilinx Virtex-7 FPGA. The Multibeam Smart Antenna example design illustrates the concepts discussed in the paper and provides design insight into Multibeam Smart Antenna implementation from the point of view of implementation complexity, required hardware, and overall system performance gain.

  7. An ASIC for fast single photon counting in the LHCb RICH upgrade

    Science.gov (United States)

    Gotti, C.

    2017-03-01

    The LHCb experiment will be upgraded during the second LHC long shutdown (years 2019–2020) to operate at higher luminosity. The new triggerless architecture of LHCb requires data from the entire detector to be read out at 40 MHz. The basic element of the front-end electronics of the Ring Imaging Cherenkov (RICH) detector upgrade is the "Elementary Cell" (EC), a readout system for multianode photomultiplier tubes designed to minimise parasitic capacitance at the anodes, to obtain a fast readout with low noise and low crosstalk. At the heart of the EC is the CLARO, an 8 channel, low power and radiation hard front-end ASIC designed in 0.35 μm CMOS technology. Each channel compares the charge signals from the photomultiplier anodes with a programmable threshold, and gives a digital pulse at the output when the threshold is exceeded. Baseline recovery occurs in less than 25 ns for typical single photon signals. In the LHCb RICH upgrade environment, the chips will have to withstand radiation up to a total ionising dose of 2 kGy (200 krad) and neutron and hadron fluences up to 03×112 cm‑2 and following irradiation, the chips have been shown to tolerate such doses with a margin of safety.

  8. Synchrotron beam test of a photon counting pixel prototype based on Double-SOI technology

    Science.gov (United States)

    Zhou, Y.; Lu, Y.; Hashimoto, R.; Nishimura, R.; Kishimoto, S.; Arai, Y.; Ouyang, Q.

    2017-01-01

    The overall noise performances and first synchrotron beam measurement results of CPIXETEG3b, the first counting type Silicon-On-Insulator (SOI) pixel sensor prototype without crosstalk issue, are reported. The prototype includes a 64 × 64 pixel matrix with 50 μm pitch size. Each pixel consists of an N-in-P charge collection diode, a charge sensitive preamplifier, a shaper, a discriminator with thresholds adjustable by an in-pixel 4-bit DAC, and a 6-bit counter. The study was performed using the beam line 14A at KEK Photon Factory (KEK-PF) . The homogeneous response of the prototype, including charging-sharing effects between pixels were studied. 16 keV and 8 keV monochromatic small size (~ 10 μm diameter) X-ray beams were used for the charge sharing study, and a flat-field was added for homogenous response investigation. The overall detector homogeneity and the influence of basic detector parameters on charge sharing between pixels has been investigated.

  9. APEnet+: high bandwidth 3D torus direct network for petaflops scale commodity clusters

    Science.gov (United States)

    Ammendola, R.; Biagioni, A.; Frezza, O.; Lo Cicero, F.; Lonardo, A.; Paolucci, P. S.; Rossetti, D.; Salamon, A.; Salina, G.; Simula, F.; Tosoratto, L.; Vicini, P.

    2011-12-01

    We describe herein the APElink+ board, a PCIe interconnect adapter featuring the latest advances in wire speed and interface technology plus hardware support for a RDMA programming model and experimental acceleration of GPU networking; this design allows us to build a low latency, high bandwidth PC cluster, the APEnet+ network, the new generation of our cost-effective, tens-of-thousands-scalable cluster network architecture. Some test results and characterization of data transmission of a complete testbench, based on a commercial development card mounting an Altera® FPGA, are provided.

  10. APEnet+: high bandwidth 3D torus direct network for petaflops scale commodity clusters

    CERN Document Server

    Ammendola, Roberto; Frezza, Ottorino; Cicero, Francesca Lo; Lonardo, Alessandro; Paolucci, Pier Stanislao; Rossetti, Davide; Salamon, Andrea; Salina, Gaetano; Simula, Francesco; Tosoratto, Laura; Vicini, Piero

    2011-01-01

    We describe herein the APElink+ board, a PCIe interconnect adapter featuring the latest advances in wire speed and interface technology plus hardware support for a RDMA programming model and experimental acceleration of GPU networking; this design allows us to build a low latency, high bandwidth PC cluster, the APEnet+ network, the new generation of our cost-effective, tens-of-thousands-scalable cluster network architecture. Some test results and characterization of data transmission of a complete testbench, based on a commercial development card mounting an Altera FPGA, are provided.

  11. Applied Techniques for High Bandwidth Data Transfers across Wide Area Networks

    Institute of Scientific and Technical Information of China (English)

    JasonLee; BillAllcock; 等

    2001-01-01

    Large distributed systems such as Computational/Data Grids require large amounts of data to be co-located with the computing facilities for processing.From our work develogpin a scalable distributed network cache.we have gained experience with techniques necessary to achieve high data throughput over high bandwidth Wide Area Networks(WAN).In this paper,we discuss several hardware and software dsign techniques,and then describe their application to an implementation of an enhanced FTP protocol called GridFTP,We describe results from the Supercomputing 2000 conference.

  12. The HOTWAXS detector

    Energy Technology Data Exchange (ETDEWEB)

    Bateman, J.E.; Derbyshire, G.E. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom); Diakun, G. [Science and Technology Facilities Council, Daresbury Laboratory, Keckwick Lane, Daresbury, Warrington WA4 4AD (United Kingdom); Duxbury, D.M. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom)], E-mail: d.m.duxbury@rl.ac.uk; Fairclough, J.P.A. [Department of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF (United Kingdom); Harvey, I.; Helsby, W.I. [Science and Technology Facilities Council, Daresbury Laboratory, Keckwick Lane, Daresbury, Warrington WA4 4AD (United Kingdom); Lipp, J.D.; Marsh, A.S.; Salisbury, J. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom); Sankar, G. [Royal Institution of GB, 21 Albemarle Street, London W1S 4BS (United Kingdom); Spill, E.J.; Stephenson, R. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom); Terrill, N.J. [Diamond Light Source LTD, Harwell Science and Innovation Campus, Diamond House, Chilton, Didcot, Oxfordshire OX11 0DE (United Kingdom)

    2007-10-11

    The development and testing of the HOTWAXS position-sensitive X-ray detector for Synchrotron Radiation Sources is described. Funded from a facility development grant, the aim of the project was to produce a high counting rate, parallax-free photon counting detector to be used in the combined studies of X-ray absorption fine structure and X-ray diffraction (XAFS/XRD), and also in the technique of small angle and wide angle X-ray scattering (SAXS/WAXS). The detector system is described together with results of experiments carried out at the Daresbury Laboratory Synchrotron Radiation Source.

  13. 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.

  14. High-Voltage Clock Driver for Photon-Counting CCD Characterization

    Science.gov (United States)

    Baker, Robert

    2013-01-01

    A document discusses the CCD97 from e2v technologies as it is being evaluated at Goddard Space Flight Center's Detector Characterization Laboratory (DCL) for possible use in ultra-low background noise space astronomy applications, such as Terrestrial Planet Finder Coronagraph (TPF-C). The CCD97 includes a photoncounting mode where the equivalent output noise is less than one electron. Use of this mode requires a clock signal at a voltage level greater than the level achievable by the existing CCD (charge-coupled-device) electronics. A high-voltage waveform generator has been developed in code 660/601 to support the CCD97 evaluation. The unit generates required clock waveforms at voltage levels from -20 to +50 V. It deals with standard and arbitrary waveforms and supports pixel rates from 50 to 500 kHz. The system is designed to interface with existing Leach CCD electronics.

  15. Waveguide-Coupled Superconducting Nanowire Single-Photon Detectors

    Science.gov (United States)

    Beyer, Andrew D.; Briggs, Ryan M.; Marsili, Francesco; Cohen, Justin D.; Meenehan, Sean M.; Painter, Oskar J.; Shaw, Matthew D.

    2015-01-01

    We have demonstrated WSi-based superconducting nanowire single-photon detectors coupled to SiNx waveguides with integrated ring resonators. This photonics platform enables the implementation of robust and efficient photon-counting detectors with fine spectral resolution near 1550 nm.

  16. Plasma Sensor for High Bandwidth Mass-Flow Measurements at High Mach Numbers with RF Link Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposal is aimed at the development of a miniature high bandwidth (1 MHz class) plasma sensor for flow measurements at high enthalpies. This device uses a...

  17. High-Bandwidth Tactical-Network Data Analysis in a High-Performance-Computing (HPC) Environment: Device Status Data

    Science.gov (United States)

    2015-09-01

    5.1.1 Basic Components The Hydra data processing framework provides an object - oriented hierarchy for organizing data processing within an HPC...ARL-CR-0780 ● SEP 2015 US Army Research Laboratory High-Bandwidth Tactical-Network Data Analysis in a High-Performance-Computing...ARL-CR-0780 ● SEP 2015 US Army Research Laboratory High-Bandwidth Tactical-Network Data Analysis in a High-Performance-Computing (HPC

  18. Three-Axis Attitude Estimation With a High-Bandwidth Angular Rate Sensor

    Science.gov (United States)

    Bayard, David S.; Green, Joseph J.

    2013-01-01

    A continuing challenge for modern instrument pointing control systems is to meet the increasingly stringent pointing performance requirements imposed by emerging advanced scientific, defense, and civilian payloads. Instruments such as adaptive optics telescopes, space interferometers, and optical communications make unprecedented demands on precision pointing capabilities. A cost-effective method was developed for increasing the pointing performance for this class of NASA applications. The solution was to develop an attitude estimator that fuses star tracker and gyro measurements with a high-bandwidth angular rotation sensor (ARS). An ARS is a rate sensor whose bandwidth extends well beyond that of the gyro, typically up to 1,000 Hz or higher. The most promising ARS sensor technology is based on a magnetohydrodynamic concept, and has recently become available commercially. The key idea is that the sensor fusion of the star tracker, gyro, and ARS provides a high-bandwidth attitude estimate suitable for supporting pointing control with a fast-steering mirror or other type of tip/tilt correction for increased performance. The ARS is relatively inexpensive and can be bolted directly next to the gyro and star tracker on the spacecraft bus. The high-bandwidth attitude estimator fuses an ARS sensor with a standard three-axis suite comprised of a gyro and star tracker. The estimation architecture is based on a dual-complementary filter (DCF) structure. The DCF takes a frequency- weighted combination of the sensors such that each sensor is most heavily weighted in a frequency region where it has the lowest noise. An important property of the DCF is that it avoids the need to model disturbance torques in the filter mechanization. This is important because the disturbance torques are generally not known in applications. This property represents an advantage over the prior art because it overcomes a weakness of the Kalman filter that arises when fusing more than one rate

  19. 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

  20. 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

  1. Photon-counting single-molecule spectroscopy for studying conformational dynamics and macromolecular interactions

    Energy Technology Data Exchange (ETDEWEB)

    Laurence, Ted Alfred

    2002-07-30

    Single-molecule methods have the potential to provide information about conformational dynamics and molecular interactions that cannot be obtained by other methods. Removal of ensemble averaging provides several benefits, including the ability to detect heterogeneous populations and the ability to observe asynchronous reactions. Single-molecule diffusion methodologies using fluorescence resonance energy transfer (FRET) are developed to monitor conformational dynamics while minimizing perturbations introduced by interactions between molecules and surfaces. These methods are used to perform studies of the folding of Chymotrypsin Inhibitor 2, a small, single-domain protein, and of single-stranded DNA (ssDNA) homopolymers. Confocal microscopy is used in combination with sensitive detectors to detect bursts of photons from fluorescently labeled biomolecules as they diffuse through the focal volume. These bursts are analyzed to extract fluorescence resonance energy transfer (FRET) efficiency. Advances in data acquisition and analysis techniques that are providing a more complete picture of the accessible molecular information are discussed. Photon Arrival-time Interval Distribution (PAID) analysis is a new method for monitoring macromolecular interactions by fluorescence detection with simultaneous determination of coincidence, brightness, diffusion time, and occupancy (proportional to concentration) of fluorescently-labeled molecules undergoing diffusion in a confocal detection volume. This method is based on recording the time of arrival of all detected photons, and then plotting the two-dimensional histogram of photon pairs, where one axis is the time interval between each pair of photons 1 and 2, and the second axis is the number of other photons detected in the time interval between photons 1 and 2. PAID is related to Fluorescence Correlation Spectroscopy (FCS) by a collapse of this histogram onto the time interval axis. PAID extends auto- and cross-correlation FCS

  2. Photon-counting single-molecule spectroscopy for studying conformational dynamics and macromolecular interactions

    Energy Technology Data Exchange (ETDEWEB)

    Laurence, Ted Alfred [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    Single-molecule methods have the potential to provide information about conformational dynamics and molecular interactions that cannot be obtained by other methods. Removal of ensemble averaging provides several benefits, including the ability to detect heterogeneous populations and the ability to observe asynchronous reactions. Single-molecule diffusion methodologies using fluorescence resonance energy transfer (FRET) are developed to monitor conformational dynamics while minimizing perturbations introduced by interactions between molecules and surfaces. These methods are used to perform studies of the folding of Chymotrypsin Inhibitor 2, a small, single-domain protein, and of single-stranded DNA (ssDNA) homopolymers. Confocal microscopy is used in combination with sensitive detectors to detect bursts of photons from fluorescently labeled biomolecules as they diffuse through the focal volume. These bursts are analyzed to extract fluorescence resonance energy transfer (FRET) efficiency. Advances in data acquisition and analysis techniques that are providing a more complete picture of the accessible molecular information are discussed. Photon Arrival-time Interval Distribution (PAID) analysis is a new method for monitoring macromolecular interactions by fluorescence detection with simultaneous determination of coincidence, brightness, diffusion time, and occupancy (proportional to concentration) of fluorescently-labeled molecules undergoing diffusion in a confocal detection volume. This method is based on recording the time of arrival of all detected photons, and then plotting the two-dimensional histogram of photon pairs, where one axis is the time interval between each pair of photons 1 and 2, and the second axis is the number of other photons detected in the time interval between photons 1 and 2. PAID is related to Fluorescence Correlation Spectroscopy (FCS) by a collapse of this histogram onto the time interval axis. PAID extends auto- and cross-correlation FCS

  3. High Bandwidth Pickup Design for Bunch Arrival-time Monitors for Free-Electron Laser

    CERN Document Server

    Angelovski, Aleksandar; Hansli, Matthias; Penirschke, Andreas; Schnepp, Sascha M; Bousonville, Michael; Schlarb, Holger; Bock, Marie Kristin; Weiland, Thomas; Jakoby, Rolf

    2012-01-01

    In this paper, we present the design and realization of high bandwidth pickup electrodes with a cutoff frequency above 40 GHz. The proposed cone-shaped pickups are part of a bunch arrival-time monitor (BAM) designed for high (> 500 pC) and low (20 pC) bunch charge operation mode providing for a time resolution of less than 10 fs for both operation modes. The proposed design has a fast voltage response, low ringing, and a resonance-free spectrum. For assessing the influence of manufacturing tolerances on the performance of the pickups, an extensive tolerance study has been performed via numerical simulations. A non-hermetic model of the pickups was built for measurement and validation purposes. The measurement and simulation results are in good agreement and demonstrate the capability of the proposed pickup system to meet the given specifications.

  4. High bandwidth pickup design for bunch arrival-time monitors for free-electron laser

    Directory of Open Access Journals (Sweden)

    Aleksandar Angelovski

    2012-11-01

    Full Text Available In this paper, we present the design and realization of high bandwidth pickup electrodes with a cutoff frequency above 40 GHz. The proposed cone-shaped pickups are part of a bunch arrival-time monitor designed for high (>500  pC and low (20 pC bunch charge operation mode providing for a time resolution of less than 10 fs for both operation modes. The proposed design has a fast voltage response, low ringing, and a resonance-free spectrum. For assessing the influence of manufacturing tolerances on the performance of the pickups, an extensive tolerance study has been performed via numerical simulations. A nonhermetic model of the pickups was built for measurement and validation purposes. The measurement and simulation results are in good agreement and demonstrate the capability of the proposed pickup system to meet the given specifications.

  5. Pickup design for high bandwidth bunch arrival-time monitors in free-electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Angelovski, Aleksandar; Penirschke, Andreas; Jakoby, Rolf [TU Darmstadt (Germany). Institut fuer Mikrowellentechnik und Photonik; Kuhl, Alexander; Schnepp, Sascha [TU Darmstadt (Germany). Graduate School of Computational Engineering; Bock, Marie Kristin; Bousonville, Michael; Schlarb, Holger [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Weiland, Thomas [TU Darmstadt (Germany). Institut fuer Theorie Elektromagnetischer Felder

    2012-07-01

    The increased demands for low bunch charge operation mode in the free-electron lasers (FELs) require an upgrade of the existing synchronization equipment. As a part of the laser-based synchronization system, the bunch arrival-time monitors (BAMs) should have a sub-10 femtosecond precision for high and low bunch charge operation. In order to fulfill the resolution demands for both modes of operation, the bandwidth of such a BAM should be increased up to a cutoff frequency of 40 GHz. In this talk, we present the design and the realization of high bandwidth cone-shaped pickup electrodes as a part of the BAM for the FEL in Hamburg (FLASH) and the European X-ray free-electron laser (European XFEL). The proposed pickup was simulated with CST STUDIO SUITE, and a non-hermetic model was built up for radio frequency (rf) measurements.

  6. High bandwidth all-optical 3×3 switch based on multimode interference structures

    Science.gov (United States)

    Le, Duy-Tien; Truong, Cao-Dung; Le, Trung-Thanh

    2017-03-01

    A high bandwidth all-optical 3×3 switch based on general interference multimode interference (GI-MMI) structure is proposed in this study. Two 3×3 multimode interference couplers are cascaded to realize an all-optical switch operating at both wavelengths of 1550 nm and 1310 nm. Two nonlinear directional couplers at two outer-arms of the structure are used as all-optical phase shifters to achieve all switching states and to control the switching states. Analytical expressions for switching operation using the transfer matrix method are presented. The beam propagation method (BPM) is used to design and optimize the whole structure. The optimal design of the all-optical phase shifters and 3×3 MMI couplers are carried out to reduce the switching power and loss.

  7. Novel high bandwidth wall shear stress sensor for ultrasonic cleaning applications

    Science.gov (United States)

    Gonzalez-Avila, S. Roberto; Prabowo, Firdaus; Ohl, Claus-Dieter

    2010-11-01

    Ultrasonic cleaning is due to the action of cavitation bubbles. The details of the cleaning mechanisms are not revealed or confirmed experimentally, yet several studies suggest that the wall shear stresses generated are very high, i.e. of the order of several thousand Pascal. Ultrasonic cleaning applications span a wide range from semiconductor manufacturing, to low pressure membrane cleaning, and the in the medical field cleaning of surgical instruments. We have developed a novel sensor to monitor and quantify cleaning activity which is (1) very sturdy, (2) has a high bandwidth of several megahertz, (3) is cheap in manufacturing costs, and (4) of very small size. We analyze the sensor signal by comparing its response time correlated to single laser induced cavitation bubbles using high-speed photography. Additionally, we will present first measurements in ultrasonic cleaning bathes using again high-speed photography. A preliminary discussion on the working mechanism of the sensor will be presented.

  8. Applied techniques for high bandwidth data transfers across wide area networks

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jason; Gunter, Dan; Tierney, Brian; Allcock, Bill; Bester, Joe; Bresnahan, John; Tuecke, Steve

    2001-04-30

    Large distributed systems such as Computational/Data Grids require large amounts of data to be co-located with the computing facilities for processing. Ensuring that the data is there in time for the computation in today's Internet is a massive problem. From our work developing a scalable distributed network cache, we have gained experience with techniques necessary to achieve high data throughput over high bandwidth Wide Area Networks (WAN). In this paper, we discuss several hardware and software design techniques and issues, and then describe their application to an implementation of an enhanced FTP protocol called GridFTP. We also describe results from two applications using these techniques, which were obtained at the Supercomputing 2000 conference.

  9. 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.

  10. 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...

  11. X-ray imaging detectors for synchrotron and XFEL sources

    OpenAIRE

    Takaki Hatsui; Heinz Graafsma

    2015-01-01

    Current trends for X-ray imaging detectors based on hybrid and monolithic detector technologies are reviewed. Hybrid detectors with photon-counting pixels have proven to be very powerful tools at synchrotrons. Recent developments continue to improve their performance, especially for higher spatial resolution at higher count rates with higher frame rates. Recent developments for X-ray free-electron laser (XFEL) experiments provide high-frame-rate integrating detectors with both high sensitivit...

  12. 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

  13. Detectors for the future of X-ray imaging.

    Science.gov (United States)

    Aslund, M; Fredenberg, E; Telman, M; Danielsson, M

    2010-01-01

    In recent decades, developments in detectors for X-ray imaging have improved dose efficiency. This has been accomplished with for example, structured scintillators such as columnar CsI, or with direct detectors where the X rays are converted to electric charge carriers in a semiconductor. Scattered radiation remains a major noise source, and fairly inefficient anti-scatter grids are still a gold standard. Hence, any future development should include improved scatter rejection. In recent years, photon-counting detectors have generated significant interest by several companies as well as academic research groups. This method eliminates electronic noise, which is an advantage in low-dose applications. Moreover, energy-sensitive photon-counting detectors allow for further improvements by optimising the signal-to-quantum-noise ratio, anatomical background subtraction or quantitative analysis of object constituents. This paper reviews state-of-the-art photon-counting detectors, scatter control and their application in diagnostic X-ray medical imaging. In particular, spectral imaging with photon-counting detectors, pitfalls such as charge sharing and high rates and various proposals for mitigation are discussed.

  14. Enhancing the Linear Dynamic Range in Multi-Channel Single Photon Detector beyond 7OD

    Science.gov (United States)

    Gudkov, Dmytro; Gudkov, George; Gorbovitski, Boris; Gorfinkel, Vera

    2015-01-01

    We present design, implementation, and characterization of a single photon detector based on 32-channel PMT sensor [model H7260-20, Hamamatsu]. The developed high speed electronics enables the photon counting with linear dynamic range (LDR) up to 108count/s per detector's channel. The experimental characterization and Monte-Carlo simulations showed that in the single photon counting mode the LDR of the PMT sensor is limited by (i) “photon” pulse width (current pulse) of 900ps and (ii) substantial decrease of amplitudes of current pulses for count rates exceeding 108 count/s. The multi-channel architecture of the detector and the developed firm/software allow further expansion of the dynamic range of the device by 32-fold by using appropriate beam shaping. The developed single photon counting detector was tested for the detection of fluorescence labeled microbeads in capillary flow. PMID:27087788

  15. Photostatistics Reconstruction via Loop Detector Signatures

    CERN Document Server

    Webb, J G; 10.1364/OE.17.011799

    2009-01-01

    Photon-number resolving detectors are a fundamental building-block of optical quantum information processing protocols. A loop detector, combined with appropriate statistical processing, can be used to convert a binary on/off photon counter into a photon-number-resolving detector. Here we describe the idea of a signature of photon-counts, which may be used to more robustly reconstruct the photon number distribution of a quantum state. The methodology is applied experimentally in a 9-port loop detector operating at a telecommunications wavelength and compared directly to the approach whereby only the number of photon-counts is used to reconstruct the input distribution. The signature approach is shown to be more robust against calibration errors, exhibit reduced statistical uncertainty, and reduced reliance on a-priori assumptions about the input state.

  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. Controllable high bandwidth storage of optical information in a Bose-Einstein Condensate

    Science.gov (United States)

    Jayaseelan, Maitreyi; Schultz, Justin T.; Murphree, Joseph D.; Hansen, Azure; Bigelow, Nicholas P.

    2016-05-01

    The storage and retrieval of optical information has been of interest for a variety of applications including quantum information processing, quantum networks and quantum memories. Several schemes have been investigated and realized with weak, narrowband pulses, including techniques using EIT in solid state systems and both hot and cold atomic vapors. In contrast, we investigate the storage and manipulation of strong, high bandwidth pulses in a Bose-Einstein Condensate (BEC) of ultracold 87 Rb atoms. As a storage medium for optical pulses, BECs offer long storage times and preserve the coherence properties of the input information, suppressing unwanted thermal decoherence effects. We present numerical simulations of nanosecond pulses addressing a three-level lambda system on the D2 line of 87 Rb. The signal pulse is stored as a localized spin excitation in the condensate and can be moved or retrieved by reapplication of successive control pulses. The relative Rabi frequencies and areas of the pulses and the local atomic density in the condensate determine the storage location and readout of the signal pulse. Extending this scheme to use beams with a variety of spatial modes such as Hermite- and Laguerre-Gaussian modes offers an expanded alphabet for information storage.

  18. International distance education and the transition from ISDN to high-bandwidth Internet connectivity.

    Science.gov (United States)

    Vincent, Dale S; Berg, Benjamin W; Chitpatima, Suwicha; Hudson, Donald

    2002-12-01

    The Thailand Hawaii Assessment of Interactive Healthcare Initiative (THAI-HI) is an international distance-education project between two teaching hospitals in Honolulu and Bangkok that uses videoconferencing over three ISDN lines. A 'morning report' format is used to discuss clinical cases primarily covering infectious disease and critical-care topics. An audience response system is used at both sites to add interactivity. From July 2001 to May 2002, 816 health-care providers attended 20 clinical conferences. Audiences rated the conferences as highly relevant and as having high training value. Since the ISDN connection is expensive, we plan to convert the telecommunications to a high-bandwidth Internet connection. The Honolulu site will use a 45 Mbit/s commercial connection to the Hawaii Intranetwork Consortium, which links to the Abilene Network on the US mainland. The Bangkok hospital will use a 155 Mbit/s wireless optical connection to UNINET Thailand, which has a 45 Mbit/s circuit to Abilene.

  19. Mahanaxar: quality of service guarantees in high-bandwidth, real-time streaming data storage

    Energy Technology Data Exchange (ETDEWEB)

    Bigelow, David [Los Alamos National Laboratory; Bent, John [Los Alamos National Laboratory; Chen, Hsing-Bung [Los Alamos National Laboratory; Brandt, Scott [UCSC

    2010-04-05

    Large radio telescopes, cyber-security systems monitoring real-time network traffic, and others have specialized data storage needs: guaranteed capture of an ultra-high-bandwidth data stream, retention of the data long enough to determine what is 'interesting,' retention of interesting data indefinitely, and concurrent read/write access to determine what data is interesting, without interrupting the ongoing capture of incoming data. Mahanaxar addresses this problem. Mahanaxar guarantees streaming real-time data capture at (nearly) the full rate of the raw device, allows concurrent read and write access to the device on a best-effort basis without interrupting the data capture, and retains data as long as possible given the available storage. It has built in mechanisms for reliability and indexing, can scale to meet arbitrary bandwidth requirements, and handles both small and large data elements equally well. Results from our prototype implementation shows that Mahanaxar provides both better guarantees and better performance than traditional file systems.

  20. High-gain, high-bandwidth, rail-to-rail, constant-gm CMOS operational amplifier

    Science.gov (United States)

    Huang, Hong-Yi; Wang, Bo-Ruei

    2013-01-01

    This study presents a high-gain, high-bandwidth, constant-gm , rail-to-rail operational amplifier (op-amp). The constant transconductance is improved with a source-to-bulk bias control of an input pair. A source degeneration scheme is also adapted to the output stage for receiving wide input range without degradation of the gain. Additionally, several compensation schemes are employed to enhance the stability. A test chip is fabricated in a 0.18 µm complementary metal-oxide semiconductor process. The active area of the op-amp is 181 × 173 µm2 and it consumes a power of 2.41 mW at a supply voltage of 1.8 V. The op-amp achieves a dc gain of 94.3 dB and a bandwidth of 45 MHz when the output capacitive load is connected to an effective load of 42.5 pF. A class-AB output stage combining a slew rate (SR) boost circuit provides a sinking current of 6 mA and an SR of 17 V/µs.

  1. Low latency, high bandwidth data communications between compute nodes in a parallel computer

    Science.gov (United States)

    Archer, Charles J.; Blocksome, Michael A.; Ratterman, Joseph D.; Smith, Brian E.

    2010-11-02

    Methods, parallel computers, and computer program products are disclosed for low latency, high bandwidth data communications between compute nodes in a parallel computer. Embodiments include receiving, by an origin direct memory access (`DMA`) engine of an origin compute node, data for transfer to a target compute node; sending, by the origin DMA engine of the origin compute node to a target DMA engine on the target compute node, a request to send (`RTS`) message; transferring, by the origin DMA engine, a predetermined portion of the data to the target compute node using memory FIFO operation; determining, by the origin DMA engine whether an acknowledgement of the RTS message has been received from the target DMA engine; if the an acknowledgement of the RTS message has not been received, transferring, by the origin DMA engine, another predetermined portion of the data to the target compute node using a memory FIFO operation; and if the acknowledgement of the RTS message has been received by the origin DMA engine, transferring, by the origin DMA engine, any remaining portion of the data to the target compute node using a direct put operation.

  2. Pixel-level Analog-To-Digital Converters for Hybrid Pixel Detectors with energy sensitivity

    NARCIS (Netherlands)

    San Segundo Bello, David; Nauta, Bram; Visschers, Jan

    2000-01-01

    Single-photon counting hybrid pixel detectors have shown to be a valid alternative to other types of X-ray imaging devices due to their high sensitivity, low noise, linear behavior and wide dynamic range. One important advantage of these devices is the fact that detector and readout electronics are

  3. Design of pixel-level ADCs for energy-sensitive hybrid pixel detectors

    NARCIS (Netherlands)

    San Segundo Bello, David; Nauta, Bram; Visschers, Jan

    2000-01-01

    Single-photon counting hybrid pixel detectors have shown to be a valid alternative to other types of X-ray imaging devices due to their high sensitivity, low noise, linear behavior and wide dynamic range. One important advantage of these devices is the fact that detector and readout electronics are

  4. Performance Evaluation of a High Bandwidth Liquid Fuel Modulation Valve for Active Combustion Control

    Science.gov (United States)

    Saus, Joseph R.; DeLaat, John C.; Chang, Clarence T.; Vrnak, Daniel R.

    2012-01-01

    At the NASA Glenn Research Center, a characterization rig was designed and constructed for the purpose of evaluating high bandwidth liquid fuel modulation devices to determine their suitability for active combustion control research. Incorporated into the rig s design are features that approximate conditions similar to those that would be encountered by a candidate device if it were installed on an actual combustion research rig. The characterized dynamic performance measures obtained through testing in the rig are planned to be accurate indicators of expected performance in an actual combustion testing environment. To evaluate how well the characterization rig predicts fuel modulator dynamic performance, characterization rig data was compared with performance data for a fuel modulator candidate when the candidate was in operation during combustion testing. Specifically, the nominal and off-nominal performance data for a magnetostrictive-actuated proportional fuel modulation valve is described. Valve performance data were collected with the characterization rig configured to emulate two different combustion rig fuel feed systems. Fuel mass flows and pressures, fuel feed line lengths, and fuel injector orifice size was approximated in the characterization rig. Valve performance data were also collected with the valve modulating the fuel into the two combustor rigs. Comparison of the predicted and actual valve performance data show that when the valve is operated near its design condition the characterization rig can appropriately predict the installed performance of the valve. Improvements to the characterization rig and accompanying modeling activities are underway to more accurately predict performance, especially for the devices under development to modulate fuel into the much smaller fuel injectors anticipated in future lean-burning low-emissions aircraft engine combustors.

  5. Design, analysis and testing of a parallel-kinematic high-bandwidth XY nanopositioning stage

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chun-Xia; Gu, Guo-Ying; Yang, Mei-Ju; Zhu, Li-Min, E-mail: zhulm@sjtu.edu.cn [State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2013-12-15

    This paper presents the design, analysis, and testing of a parallel-kinematic high-bandwidth XY nanopositioning stage driven by piezoelectric stack actuators. The stage is designed with two kinematic chains. In each kinematic chain, the end-effector of the stage is connected to the base by two symmetrically distributed flexure modules, respectively. Each flexure module comprises a fixed-fixed beam and a parallelogram flexure serving as two orthogonal prismatic joints. With the purpose to achieve high resonance frequencies of the stage, a novel center-thickened beam which has large stiffness is proposed to act as the fixed-fixed beam. The center-thickened beam also contributes to reducing cross-coupling and restricting parasitic motion. To decouple the motion in two axes totally, a symmetric configuration is adopted for the parallelogram flexures. Based on the analytical models established in static and dynamic analysis, the dimensions of the stage are optimized in order to maximize the first resonance frequency. Then finite element analysis is utilized to validate the design and a prototype of the stage is fabricated for performance tests. According to the results of static and dynamic tests, the resonance frequencies of the developed stage are over 13.6 kHz and the workspace is 11.2 μm × 11.6 μm with the cross-coupling between two axes less than 0.52%. It is clearly demonstrated that the developed stage has high resonance frequencies, a relatively large travel range, and nearly decoupled performance between two axes. For high-speed tracking performance tests, an inversion-based feedforward controller is implemented for the stage to compensate for the positioning errors caused by mechanical vibration. The experimental results show that good tracking performance at high speed is achieved, which validates the effectiveness of the developed stage.

  6. 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

  7. Hybrid photon detectors

    CERN Document Server

    D'Ambrosio, C

    2003-01-01

    Hybrid photon detectors detect light via vacuum photocathodes and accelerate the emitted photoelectrons by an electric field towards inversely polarized silicon anodes, where they are absorbed, thus producing electron-hole pairs. These, in turn, are collected and generate electronic signals on their ohmic contacts. This review first describes the characteristic properties of the main components of hybrid photon detectors: light entrance windows, photocathodes, and silicon anodes. Then, essential relations describing the trajectories of photoelectrons in electric and magnetic fields and their backscattering from the silicon anodes are derived. Depending on their anode configurations, three families of hybrid photon detectors are presented: hybrid photomultiplier tubes with single anodes for photon counting with high sensitivity and for gamma spectroscopy; multi-anode photon detector tubes with anodes subdivided into square or hexagonal pads for position-sensitive photon detection; imaging silicon pixel array t...

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 2Kx2K resolution element photon counting MCP sensor with >200 kHz event rate capability

    CERN Document Server

    Vallerga, J V

    2000-01-01

    Siegmund Scientific undertook a NASA Small Business Innovative Research (SBIR) contract to develop a versatile, high-performance photon (or particle) counting detector combining recent technical advances in all aspects of Microchannel Plate (MCP) detector development in a low cost, commercially viable package that can support a variety of applications. The detector concept consists of a set of MCPs whose output electron pulses are read out with a crossed delay line (XDL) anode and associated high-speed event encoding electronics. The delay line anode allows high-resolution photon event centroiding at very high event rates and can be scaled to large formats (>40 mm) while maintaining good linearity and high temporal stability. The optimal sensitivity wavelength range is determined by the choice of opaque photocathodes. Specific achievements included: spatial resolution of 200 000 events s sup - sup 1; local rates of >100 events s sup - sup 1 per resolution element; event timing of <1 ns; and low background ...

  15. Silicon Photonics for All-Optical Processing and High-Bandwidth-Density Interconnects

    Science.gov (United States)

    Ophir, Noam

    The first chapter of the thesis provides motivation for the integration of silicon photonic modules into compute systems and surveys some of the recent developments in the field. The second chapter then proceeds to detail a technical case study of silicon photonic microring-based WDM links' scalability and power efficiency for these chip I/O applications which could be developed in the intermediate future. The analysis, initiated originally for a workshop on optical and electrical board and rack level interconnects, looks into a detailed model of the optical power budget for such a link capturing both single-channel aspects as well as WDM-operation-related considerations which are unique for a microring physical characteristics. The third chapter, while continuing on the theme silicon photonic high bandwidth density links, proceeds to detail the first experimental demonstration and characterization of an on-chip spatial division multiplexing (SDM) scheme based on microrings for the multiplexing and demultiplexing functionalities. In the context of more forward looking optical network-on-chip environments, SDM-enabled WDM photonic interconnects can potentially achieve superior bandwidth densities per waveguide compared to WDM-only photonic interconnects. The microring-based implementation allows dynamic tuning of the multiplexing and demultiplexing characteristic of the system which allows operation on WDM grid as well device tuning to combat intra-channel crosstalk. The characterization focuses on the first reported power penalty measurements for on-chip silicon photonic SDM link showing minimal penalties achievable with 3 spatial modes concurrently operating on a single waveguide with 10-Gb/s data carried by each mode. The fourth, fifth, and sixth chapters shift in topic from the application of silicon photonics to communication links to the evolving use of silicon waveguides for nonlinear all-optical processing. Chapter four primarily introduces and motivates

  16. Scalable multiplexed detector system for high-rate telecom-band single-photon detection.

    Science.gov (United States)

    Brida, G; Degiovanni, I P; Piacentini, F; Schettini, V; Polyakov, S V; Migdall, A

    2009-11-01

    We present an actively multiplexed photon-counting detection system at telecom wavelengths that overcomes the difficulties of photon-counting at high rates. We find that for gated detectors, the heretofore unconsidered deadtime associated with the detector gate is a critical parameter, that limits the overall scalability of the scheme to just a few detectors. We propose and implement a new scheme that overcomes this problem and restores full scalability that allows an order of magnitude improvement with systems with as few as 4 detectors. When using just two multiplexed detectors, our experimental results show a 5x improvement over a single detector and a greater than 2x improvement over multiplexed schemes that do not consider gate deadtime.

  17. High-bandwidth squeezed light at 1550 nm from a compact monolithic PPKTP cavity

    CERN Document Server

    Ast, Stefan; Schnabel, Roman

    2013-01-01

    We report the generation of squeezed vacuum states of light at 1550 nm with a broadband quantum noise reduction of up to 4.8 dB ranging from 5 MHz to 1.2 GHz sideband frequency. We used a custom-designed 2.6 mm long biconvex periodically-poled potassium titanyl phosphate (PPKTP) crystal. It featured reflectively coated end surfaces, 2.26 GHz of linewidth and generated the squeezing via optical parametric amplification. Two homodyne detectors with different quantum efficiencies and bandwidths were used to characterize the non-classical noise suppression. We measured squeezing values of up to 4.8 dB from 5 to 100 MHz and up to 3 dB from 100 MHz to 1.2 GHz. The squeezed vacuum measurements were limited by detection loss. We propose an improved detection scheme to measure up to 10 dB squeezing over 1 GHz. Our results of GHz bandwidth squeezed light generation provide new prospects for high-speed quantum key distribution.

  18. 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.

  19. High-bandwidth Modulation of H2/Syngas Fuel to Control Combustion Dynamics in Micro-Mixing Lean Premix Systems

    Energy Technology Data Exchange (ETDEWEB)

    Jeff Melzak; Tim Lieuwen; Adel Mansour

    2012-01-31

    The goal of this program was to develop and demonstrate fuel injection technologies that will facilitate the development of cost-effective turbine engines for Integrated Gasification Combined Cycle (IGCC) power plants, while improving efficiency and reducing emissions. The program involved developing a next-generation multi-point injector with enhanced stability performance for lean premix turbine systems that burn hydrogen (H2) or synthesis gas (syngas) fuels. A previously developed injector that demonstrated superior emissions performance was improved to enhance static flame stability through zone staging and pilot sheltering. In addition, piezo valve technology was implemented to investigate the potential for enhanced dynamic stability through high-bandwidth modulation of the fuel supply. Prototype injector and valve hardware were tested in an atmospheric combustion facility. The program was successful in meeting its objectives. Specifically, the following was accomplished: Demonstrated improvement of lean operability of the Parker multi-point injector through staging of fuel flow and primary zone sheltering; Developed a piezo valve capable of proportional and high-bandwidth modulation of gaseous fuel flow at frequencies as high as 500 Hz; The valve was shown to be capable of effecting changes to flame dynamics, heat release, and acoustic signature of an atmospheric combustor. The latter achievement indicates the viability of the Parker piezo valve technology for use in future adaptively controlled systems for the mitigation of combustion instabilities, particularly for attenuating combustion dynamics under ultra-lean conditions.

  20. High-voltage integrated active quenching circuit for single photon count rate up to 80 Mcounts/s.

    Science.gov (United States)

    Acconcia, Giulia; Rech, Ivan; Gulinatti, Angelo; Ghioni, Massimo

    2016-08-01

    Single photon avalanche diodes (SPADs) have been subject to a fast improvement in recent years. In particular, custom technologies specifically developed to fabricate SPAD devices give the designer the freedom to pursue the best detector performance required by applications. A significant breakthrough in this field is represented by the recent introduction of a red enhanced SPAD (RE-SPAD) technology, capable of attaining a good photon detection efficiency in the near infrared range (e.g. 40% at a wavelength of 800 nm) while maintaining a remarkable timing resolution of about 100ps full width at half maximum. Being planar, the RE-SPAD custom technology opened the way to the development of SPAD arrays particularly suited for demanding applications in the field of life sciences. However, to achieve such excellent performance custom SPAD detectors must be operated with an external active quenching circuit (AQC) designed on purpose. Next steps toward the development of compact and practical multichannel systems will require a new generation of monolithically integrated AQC arrays. In this paper we present a new, fully integrated AQC fabricated in a high-voltage 0.18 µm CMOS technology able to provide quenching pulses up to 50 Volts with fast leading and trailing edges. Although specifically designed for optimal operation of RE-SPAD devices, the new AQC is quite versatile: it can be used with any SPAD detector, regardless its fabrication technology, reaching remarkable count rates up to 80 Mcounts/s and generating a photon detection pulse with a timing jitter as low as 119 ps full width at half maximum. The compact design of our circuit has been specifically laid out to make this IC a suitable building block for monolithically integrated AQC arrays.

  1. 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.

  2. 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.

  3. Photon counting with photon number resolution through superconducting nanowires coupled to a multi-channel TDC in FPGA

    Science.gov (United States)

    Lusardi, N.; Los, J. W. N.; Gourgues, R. B. M.; Bulgarini, G.; Geraci, A.

    2017-03-01

    The paper presents a system for measuring photon statistics and photon timing in the few-photon regime down to the single-photon level. The measurement system is based on superconducting nanowire single photon detectors and a time-to-digital converter implemented into a programmable device. The combination of these devices gives high performance to the system in terms of resolution and adaptability to the actual experimental conditions. As a case of application, we present the measurement of photon statistics for coherent light states. In this measurement, we make use of 8th order single photon correlations to reconstruct with high fidelity the statistics of a coherent state with average photon number up to 4. The processing is performed by means of a tapped-delay-line time-to-digital converter architecture that also hosts an asynchronous-correlated-digital-counter implemented in a field programmable gate array device and specifically designed for performance optimization in multi-channel usage.

  4. The solid state detector technology for picosecond laser ranging

    Science.gov (United States)

    Prochazka, Ivan

    1993-01-01

    We developed an all solid state laser ranging detector technology, which makes the goal of millimeter accuracy achievable. Our design and construction philosophy is to combine the techniques of single photon ranging, ultrashort laser pulses, and fast fixed threshold discrimination while avoiding any analog signal processing within the laser ranging chain. The all solid state laser ranging detector package consists of the START detector and the STOP solid state photon counting module. Both the detectors are working in an optically triggered avalanche switching regime. The optical signal is triggering an avalanche current buildup which results in the generation of a uniform, fast risetime output pulse.

  5. High-Bandwidth Atomic Force Microscopy Reveals A Mechanical spike Accompanying the Action Potential in mammalian Nerve Terminals

    Science.gov (United States)

    Salzberg, Brian M.

    2008-03-01

    Information transfer from neuron to neuron within nervous systems occurs when the action potential arrives at a nerve terminal and initiates the release of a chemical messenger (neurotransmitter). In the mammalian neurohypophysis (posterior pituitary), large and rapid changes in light scattering accompany secretion of transmitter-like neuropeptides. In the mouse, these intrinsic optical signals are intimately related to the arrival of the action potential (E-wave) and the release of arginine vasopressin and oxytocin (S-wave). We have used a high bandwidth (20 kHz) atomic force microscope (AFM) to demonstrate that these light scattering signals are associated with changes in nerve terminal volume, detected as nanometer-scale movements of a cantilever positioned on top of the neurohypophysis. The most rapid mechanical response, the ``spike'', has duration comparable to that of the action potential (˜2 ms) and probably reflects an increase in terminal volume due to H2O movement associated with Na^+-influx. Elementary calculations suggest that two H2O molecules accompanying each Na^+-ion could account for the ˜0.5-1.0 å increase in the diameter of each terminal during the action potential. Distinguishable from the mechanical ``spike'', a slower mechanical event, the ``dip'', represents a decrease in nerve terminal volume, depends upon Ca^2+-entry, as well as on intra-terminal Ca^2+-transients, and appears to monitor events associated with secretion. A simple hypothesis is that this ``dip'' reflects the extrusion of the dense core granule that comprises the secretory products. These dynamic high bandwidth AFM recordings are the first to monitor mechanical events in nervous systems and may provide novel insights into the mechanism(s) by which excitation is coupled to secretion at nerve terminals.

  6. Prospects and fundamental limitations of room temperature, non-avalanche, semiconductor photon-counting sensors (Conference Presentation)

    Science.gov (United States)

    Ma, Jiaju; Zhang, Yang; Wang, Xiaoxin; Ying, Lei; Masoodian, Saleh; Wang, Zhiyuan; Starkey, Dakota A.; Deng, Wei; Kumar, Rahul; Wu, Yang; Ghetmiri, Seyed Amir; Yu, Zongfu; Yu, Shui-Qing; Salamo, Gregory J.; Fossum, Eric R.; Liu, Jifeng

    2017-05-01

    This research investigates the fundamental limits and trade-space of quantum semiconductor photodetectors using the Schrödinger equation and the laws of thermodynamics.We envision that, to optimize the metrics of single photon detection, it is critical to maximize the optical absorption in the minimal volume and minimize the carrier transit process simultaneously. Integration of photon management with quantum charge transport/redistribution upon optical excitation can be engineered to maximize the quantum efficiency (QE) and data rate and minimize timing jitter at the same time. Due to the ultra-low capacitance of these quantum devices, even a single photoelectron transfer can induce a notable change in the voltage, enabling non-avalanche single photon detection at room temperature as has been recently demonstrated in Si quanta image sensors (QIS). In this research, uniform III-V quantum dots (QDs) and Si QIS are used as model systems to test the theory experimentally. Based on the fundamental understanding, we also propose proof-of-concept, photon-managed quantum capacitance photodetectors. Built upon the concepts of QIS and single electron transistor (SET), this novel device structure provides a model system to synergistically test the fundamental limits and tradespace predicted by the theory for semiconductor detectors. This project is sponsored under DARPA/ARO's DETECT Program: Fundamental Limits of Quantum Semiconductor Photodetectors.

  7. 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

  8. A multi-channel high time resolution detector for high content imaging

    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

    Medical imaging has long benefited from advances in photon counting detectors arising from space and particle physics. We describe a microchannel plate-based detector system for high content (multi-parametric) analysis, specifically designed to provide a step change in performance and throughput for measurements in imaged live cells and tissue for the ‘omics’. The detector system integrates multi-channel, high time resolution, photon counting capability into a single miniaturized detector with integrated ASIC electronics, comprising a fast, low power amplifier discriminator and TDC for every channel of the discrete pixel electronic readout, and achieving a pixel density improvement of order two magnitudes compared with current comparable devices. The device combines high performance, easy reconfigurability, and economy within a compact footprint. We present simulations and preliminary measurements in the context of our ultimate goals of 20 ps time resolution with multi-channel parallel analysis (1024 chan...

  9. Development of a high-speed single-photon pixellated detector for visible wavelengths

    CERN Document Server

    Mac Raighne, Aaron; Mathot, Serge; McPhate, Jason; Vallerga, John; Jarron, Pierre; Brownlee, Colin; O’Shea, Val

    2009-01-01

    We present the development of a high-speed, single-photon counting, Hybrid Photo Detector (HPD). The HPD consists of a vacuum tube, containing the detector assembly, sealed with a transparent optical input window. Photons incident on the photocathode eject a photoelectron into a large electric field, which accelerates the incident electron onto a silicon detector. The silicon detector is bump bonded to a Medipix readout chip. This set-up allows for the detection and readout of low incident photon intensities at rates that are otherwise unattainable with current camera technology. Reported is the fabrication of the camera that brings together a range of sophisticated design and fabrication techniques and the expected theoretical imaging performance. Applications to cellular and molecular microscopy are also described in which single-photon-counting abilities at high frame rates are crucial

  10. 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.

  11. 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

  12. ATLAS ITk Pixel detector

    CERN Document Server

    Gemme, Claudia; The ATLAS collaboration

    2016-01-01

    The high luminosity upgrade of the LHC (HL-LHC) in 2026 will provide new challenge to the ATLAS tracker. The current inner detector will be replaced with a whole silicon tracker which will consist of a five barrel layer Pixel detector surrounded by a four barrel layer Strip detector. The expected high radiation level are requiring the development of upgraded silicon sensors as well as new a front-end chip. The dense tracking environment will require finer granularity detectors. The data rates will require new technologies for high bandwidth data transmission and handling. The current status of the HL-LHC ATLA Pixel detector developments as well as the various layout options will be reviewed.

  13. Electro-optic prism-pair setup for efficient high bandwidth isochronous CEP phase shift or group delay generation

    Science.gov (United States)

    Gobert, Olivier; Mennerat, Gabriel; Cornaggia, Christian; Lupinski, Dominique; Perdrix, Michel; Guillaumet, Delphine; Lepetit, Fabien; Oksenhendler, Thomas; Comte, Michel

    2016-05-01

    We report the experimental demonstration of an electro-optic prism pair pure carrier-envelope phase (CEP) shifter at low voltage (shift of 1 rad for a voltage of 90 V, applied to a crystal of 5 mm aperture). Validating our mathematical model, the experiments prove that this set-up which uses two rubidium titanyl phosphate (RTP) crystals, can be used either as an efficient high bandwidth CEP shifter without modifying the group delay of an ultrashort pulse (isochronous CEP shifter) or alternatively as a group delay generator with quasi-constant CEP (Pure Group Delay generator). These two configurations which correspond to specific geometries are characterized by spectral interferometry with a 800 nm mode-locked Ti:sapphire laser. The results are in very good agreement with the model. In the pure group delay mode, a group delay of 2.3 fs is obtained at 1000 V/cm without significant CEP shift. In the isochronous mode, a shift of 5.5 rad at 1000 V/cm is generated without significant delay. The applied voltage is also lowered by a factor of nearly three in this configuration, compared to the case of an RTP rectangular slab of the same total length.

  14. Semiconductor radiation detector with internal gain

    Energy Technology Data Exchange (ETDEWEB)

    Iwanczyk, Jan (Los Angeles, CA); Patt, Bradley E. (Sherman Oaks, CA); Vilkelis, Gintas (Westlake Village, CA)

    2003-04-01

    An avalanche drift photodetector (ADP) incorporates extremely low capacitance of a silicon drift photodetector (SDP) and internal gain that mitigates the surface leakage current noise of an avalanche photodetector (APD). The ADP can be coupled with scintillators such as CsI(Tl), NaI(Tl), LSO or others to form large volume scintillation type gamma ray detectors for gamma ray spectroscopy, photon counting, gamma ray counting, etc. Arrays of the ADPs can be used to replace the photomultiplier tubes (PMTs) used in conjunction with scintillation crystals in conventional gamma cameras for nuclear medical imaging.

  15. X-ray imaging detectors for synchrotron and XFEL sources

    Directory of Open Access Journals (Sweden)

    Takaki Hatsui

    2015-05-01

    Full Text Available Current trends for X-ray imaging detectors based on hybrid and monolithic detector technologies are reviewed. Hybrid detectors with photon-counting pixels have proven to be very powerful tools at synchrotrons. Recent developments continue to improve their performance, especially for higher spatial resolution at higher count rates with higher frame rates. Recent developments for X-ray free-electron laser (XFEL experiments provide high-frame-rate integrating detectors with both high sensitivity and high peak signal. Similar performance improvements are sought in monolithic detectors. The monolithic approach also offers a lower noise floor, which is required for the detection of soft X-ray photons. The link between technology development and detector performance is described briefly in the context of potential future capabilities for X-ray imaging detectors.

  16. X-ray imaging detectors for synchrotron and XFEL sources.

    Science.gov (United States)

    Hatsui, Takaki; Graafsma, Heinz

    2015-05-01

    Current trends for X-ray imaging detectors based on hybrid and monolithic detector technologies are reviewed. Hybrid detectors with photon-counting pixels have proven to be very powerful tools at synchrotrons. Recent developments continue to improve their performance, especially for higher spatial resolution at higher count rates with higher frame rates. Recent developments for X-ray free-electron laser (XFEL) experiments provide high-frame-rate integrating detectors with both high sensitivity and high peak signal. Similar performance improvements are sought in monolithic detectors. The monolithic approach also offers a lower noise floor, which is required for the detection of soft X-ray photons. The link between technology development and detector performance is described briefly in the context of potential future capabilities for X-ray imaging detectors.

  17. Ultraviolet imaging detectors for the GOLD mission

    Science.gov (United States)

    Siegmund, O. H. W.; McPhate, J.; Curtis, T.; Jelinsky, S.; Vallerga, J. V.; Hull, J.; Tedesco, J.

    2016-07-01

    The GOLD mission is a NASA Explorer class ultraviolet Earth observing spectroscopy instrument that will be flown on a telecommunications satellite in geostationary orbit in 2018. Microchannel plate detectors operating in the 132 nm to 162 nm FUV bandpass with 2D imaging cross delay line readouts and electronics have been built for each of the two spectrometer channels for GOLD. The detectors are "open face" with CsI photocathodes, providing 30% efficiency at 130.4 nm and 15% efficiency at 160.8 nm. These detectors with their position encoding electronics provide 600 x 500 FWHM resolution elements and are photon counting, with event handling rates of > 200 KHz. The operational details of the detectors and their performance are discussed.

  18. Sources, instrumentation and detectors for protein crystallography

    CERN Document Server

    Nave, C

    2001-01-01

    Some of the requirements for protein crystallography experiments on a synchrotron are described. Although data from different types of crystal are often collected without changing the X-ray beam properties, there are benefits if the incident beam is matched to a particular crystal and its diffraction pattern. These benefits are described with some examples. Radiation damage and other effects impose limits on the dose and dose rate on a protein crystal if the maximum amount of data is to be obtained. These limitations have possible consequences for the X-ray source required. Presently available commercial detector systems provide excellent data for protein crystallography but do not quite reach the specifications of the 'ideal' detector. In order to collect the most accurate data (e.g. for very weak anomalous scattering applications) detectors that produce near photon counting statistics over a wide dynamic range are required. It is possible that developments in 'pixel' detectors will allow these demanding exp...

  19. Charge-sharing observations with a CdTe pixel detector irradiated with a{sup 57}Co source

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-07-01

    Charge sharing is a limiting factor of detector spatial resolution and contrast in photon counting imaging devices because 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 this topic has been debated for a long time, the full impact of charge sharing has not been completely assessed. In this work, we look at the importance of charge sharing in CdTe pixel detectors by exposing such a device to a low-activity (37 kBq){sup 57}Co source, whose main emission line is at 122 keV.The detectors used are 1 mm thick with a pixel pitch of 55 {mu}m. These detectors are bump-bonded to Medipix2 photon-counting chips. This study gives an insight of the impact on the design and operation of pixel detectors coupled to photon-counting devices for imaging applications.

  20. Charge-sharing observations with a CdTe pixel detector irradiated with a 57Co source

    Science.gov (United States)

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

    2006-07-01

    Charge sharing is a limiting factor of detector spatial resolution and contrast in photon counting imaging devices because 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 this topic has been debated for a long time, the full impact of charge sharing has not been completely assessed. In this work, we look at the importance of charge sharing in CdTe pixel detectors by exposing such a device to a low-activity (37 kBq) 57Co source, whose main emission line is at 122 keV.The detectors used are 1 mm thick with a pixel pitch of 55 μm. These detectors are bump-bonded to Medipix2 photon-counting chips. This study gives an insight of the impact on the design and operation of pixel detectors coupled to photon-counting devices for imaging applications.

  1. Analysis of the possibility of analog detectors calibration by exploiting stimulated parametric down conversion.

    Science.gov (United States)

    Brida, Giorgio; Chekhova, Maria; Genovese, Marco; Ruo-Berchera, Ivano

    2008-08-18

    Spontaneous parametric down conversion (SPDC) has been largely exploited as a tool for absolute calibration of photon-counting detectors, i.e detectors registering very small photon fluxes. In [J. Opt. Soc. Am. B 23, 2185 (2006)] we derived a method for absolute calibration of analog detectors using SPDC emission at higher photon fluxes, where the beam is seen as a continuum by the detector. Nevertheless intrinsic limitations appear when high-gain regime of SPDC is required to reach even larger photon fluxes. Here we show that stimulated parametric down conversion allow one to avoid this limitation, since stimulated photon fluxes are increased by the presence of the seed beam.

  2. Material reconstruction for spectral computed tomography with detector response function

    Science.gov (United States)

    Liu, Jiulong; Gao, Hao

    2016-11-01

    Different from conventional computed tomography (CT), spectral CT using energy-resolved photon-counting detectors is able to provide the unprecedented material compositions. However accurate spectral CT needs to account for the detector response function (DRF), which is often distorted by factors such as pulse pileup and charge-sharing. In this work, we propose material reconstruction methods for spectral CT with DRF. The simulation results suggest that the proposed methods reconstructed more accurate material compositions than the conventional method without DRF. Moreover, the proposed linearized method with linear data fidelity from spectral resampling had improved reconstruction quality from the nonlinear method directly based on nonlinear data fidelity.

  3. Single-step absorption and phase retrieval with polychromatic x rays using a spectral detector.

    Science.gov (United States)

    Gürsoy, Doğa; Das, Mini

    2013-05-01

    In this Letter, we present a single-step method to simultaneously retrieve x-ray absorption and phase images valid for a broad range of imaging energies and material properties. Our method relies on the availability of spectrally resolved intensity measurements, which is now possible using semiconductor x-ray photon counting detectors. The retrieval method is derived and presented, with results showing good agreement.

  4. 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...

  5. Comparison of allocation algorithms for unambiguous registration of hits in presence of charge sharing in pixel detectors

    Science.gov (United States)

    Otfinowski, P.; Maj, P.; Deptuch, G.; Fahim, F.; Hoff, J.

    2017-01-01

    Charge sharing is the fractional collection of the charge cloud generated in a detector by two or more adjacent pixels. It may lead to excessive or inefficient registration of hits comparing to the number of impinging photons depending on how discrimination thresholds are set in typical photon counting pixel detector. The problems are particularly exposed for fine pixel sizes and/or for thick planar detectors. Presence of charge sharing is one of the limiting factors that discourages decreasing sizes of pixels in photon counting mode X-ray radiation imaging systems. Currently, a few different approaches tackling with the charge sharing problem exist (e.g. Medipix3RX, PIXIE, miniVIPIC or PIX45). The general idea is, first, to reconstruct the entire signal from adjacent pixels and, secondly, to allocate the hit to a single pixel. This paper focuses on the latter part of the process, i.e. on a comparison of how different hit allocation algorithms affect the spatial accuracy and false registration vs. missed hit probability. Different hit allocation algorithms were simulated, including standard photon counting (no full signal reconstruction) and the C8P1 algorithm. Also, a novel approach, based on a detection of patterns, with significantly limited analog signal processing, was proposed and characterized.

  6. CZT strip detectors for imaging and spectroscopy: Collimated beam and ASIC readout experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kurczynski, P. [Univ. of Maryland, College Park, MD (United States); Krizmanic, J.F.; Parsons, A. [Goddard Space Flight Center, Greenbelt, MD (United States)

    1996-12-31

    We report the status of ongoing investigations into Cadmium Zinc Telluride (CZT) strip detectors for application in hard x-ray astronomy. We have instrumented a nine strip by nine strip region of a two sided strip detector made in our detector fabrication facility. In order to measure the position resolution of our detectors, we have implemented a collimated beam that concentrates radiation to a spot size less than the strip width of our detector. We have also performed charge collection studies as a function of incident photon energy and bias voltage with a single sided, 100{mu}m pitch CZT strip detector wire bonded to an SVX ASIC charge amplifier. The detectors exhibited excellent strip uniformity in terms of photon count rate and spectroscopic information.

  7. 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.

  8. Energy-resolved X-ray detectors: the future of diagnostic imaging

    OpenAIRE

    Pacella D

    2015-01-01

    Danilo Pacella ENEA-Frascati, Rome, Italy Abstract: This paper presents recent progress in the field of X-ray detectors, which could play a role in medical imaging in the near future, with special attention to the new generation of complementary metal-oxide semiconductor (C-MOS) imagers, working in photon counting, that opened the way to the energy-resolved X-ray imaging. A brief description of the detectors used so far in medical imaging (photographic films, imaging plates, flat panel detec...

  9. A Sealed, UHV Compatible, Soft X-ray Detector Utilizing Gas Electron Multipliers

    Energy Technology Data Exchange (ETDEWEB)

    Schaknowski, N.A.; Smith, G.

    2009-10-25

    An advanced soft X-ray detector has been designed and fabricated for use in synchrotron experiments that utilize X-ray absorption spectroscopy in the study a wide range of materials properties. Fluorescence X-rays, in particular C{sub K} at 277eV, are converted in a low pressure gas medium, and charge multiplication occurs in two gas electron multipliers, fabricated in-house from glass reinforced laminate, to enable single photon counting. The detector satisfies a number of demanding characteristics often required in synchrotron environments, such as UHV compatibility compactness, long-term stability, and energy resolving capability.

  10. 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.

  11. Single software platform used for high speed data transfer implementation in a 65k pixel camera working in single photon counting mode

    Science.gov (United States)

    Maj, P.; Kasiński, K.; Gryboś, P.; Szczygieł, R.; Kozioł, A.

    2015-12-01

    Integrated circuits designed for specific applications generally use non-standard communication methods. Hybrid pixel detector readout electronics produces a huge amount of data as a result of number of frames per seconds. The data needs to be transmitted to a higher level system without limiting the ASIC's capabilities. Nowadays, the Camera Link interface is still one of the fastest communication methods, allowing transmission speeds up to 800 MB/s. In order to communicate between a higher level system and the ASIC with a dedicated protocol, an FPGA with dedicated code is required. The configuration data is received from the PC and written to the ASIC. At the same time, the same FPGA should be able to transmit the data from the ASIC to the PC at the very high speed. The camera should be an embedded system enabling autonomous operation and self-monitoring. In the presented solution, at least three different hardware platforms are used—FPGA, microprocessor with real-time operating system and the PC with end-user software. We present the use of a single software platform for high speed data transfer from 65k pixel camera to the personal computer.

  12. A readout for large arrays of microwave kinetic inductance detectors.

    Science.gov (United States)

    McHugh, Sean; Mazin, Benjamin A; Serfass, Bruno; Meeker, Seth; O'Brien, Kieran; Duan, Ran; Raffanti, Rick; Werthimer, Dan

    2012-04-01

    Microwave kinetic inductance detectors (MKIDs) are superconducting detectors capable of counting single photons and measuring their energy in the UV, optical, and near-IR. MKIDs feature intrinsic frequency domain multiplexing (FDM) at microwave frequencies, allowing the construction and readout of large arrays. Due to the microwave FDM, MKIDs do not require the complex cryogenic multiplexing electronics used for similar detectors, such as transition edge sensors, but instead transfer this complexity to room temperature electronics where they present a formidable signal processing challenge. In this paper, we describe the first successful effort to build a readout for a photon counting optical/near-IR astronomical instrument, the ARray Camera for Optical to Near-infrared Spectrophotometry. This readout is based on open source hardware developed by the Collaboration for Astronomy Signal Processing and Electronics Research. Designed principally for radio telescope backends, it is flexible enough to be used for a variety of signal processing applications.

  13. Signal variations in high granularity Si pixel detectors

    CERN Document Server

    Tlustos, L; Heijne, Erik H M; Llopart-Cudie, Xavier

    2004-01-01

    Fixed pattern noise is one of the limiting factors of image quality and degrades the achievable spatial resolution. In the case of silicon sensors non-uniformities due to doping inhomogeneities can be limited by operating the sensor in strong overdepletion. For high granularity photon counting pixel detectors an additional high frequency interpixel signal variation is an important factor for the achievable signal to noise ratio (SNR). It is common practice to apply flatfield corrections to increase the SNR of the detector system. For the case of direct conversion detectors it can be shown that the Poisson limit can be reached for floodfield irradiation. However when used for imaging with spectral X-ray sources flatfield corrections are less effective. This is partly a consequence of charge sharing between adjacent pixels, which gives rise to an effective energy spectrum seen by the readout, which is different from the spectral content of the incident beam. In this paper we present simulations and measurements...

  14. A readout for large arrays of Microwave Kinetic Inductance Detectors

    CERN Document Server

    McHugh, Sean; Serfass, Bruno; Meeker, Seth; O'Brien, Kieran; Duan, Ran; Raffanti, Rick; Werthimer, Dan

    2012-01-01

    Microwave Kinetic Inductance Detectors (MKIDs) are superconducting detectors capable of counting single photons and measuring their energy in the UV, optical, and near-IR. MKIDs feature intrinsic frequency domain multiplexing (FDM) at microwave frequencies, allowing the construction and readout of large arrays. Due to the microwave FDM, MKIDs do not require the complex cryogenic multiplexing electronics used for similar detectors, such as Transition Edge Sensors (TESs), but instead transfer this complexity to room temperature electronics where they present a formidable signal processing challenge. In this paper we describe the first successful effort to build a readout for a photon counting optical/near-IR astronomical instrument, the ARray Camera for Optical to Near-infrared Spectrophotometry (ARCONS). This readout is based on open source hardware developed by the Collaboration for Astronomy Signal Processing and Electronics Research (CASPER). Designed principally for radio telescope backends, it is flexible...

  15. Upgrade of ATLAS ITk Pixel Detector

    CERN Document Server

    Huegging, Fabian; The ATLAS collaboration

    2017-01-01

    The high luminosity upgrade of the LHC (HL-LHC) in 2026 will provide new challenges to the ATLAS tracker. The current inner detector will be replaced with an entirely-silicon inner tracker (ITk) which will consist of a five barrel layer Pixel detector surrounded by a four barrel layer Strip detector. The expected high radiation levels are requiring the development of upgraded silicon sensors as well as new a front-end chip. The dense tracking environment will require finer granularity detectors and low mass global and local support structures. The data rates will require new technologies for high bandwidth data transmission and handling. The current status of the ITk ATLAS Pixel detector developments as well as different layout options will be reviewed.

  16. Coherent detection of weak signals with superconducting nanowire single photon detector at the telecommunication wavelength

    Science.gov (United States)

    Shcherbatenko, M.; Lobanov, Y.; Semenov, A.; Kovalyuk, V.; Korneev, A.; Ozhegov, R.; Kaurova, N.; Voronov, B.; Goltsman, G.

    2017-05-01

    Achievement of the ultimate sensitivity along with a high spectral resolution is one of the frequently addressed problems, as the complication of the applied and fundamental scientific tasks being explored is growing up gradually. In our work, we have investigated performance of a superconducting nanowire photon-counting detector operating in the coherent mode for detection of weak signals at the telecommunication wavelength. Quantum-noise limited sensitivity of the detector was ensured by the nature of the photon-counting detection and restricted by the quantum efficiency of the detector only. Spectral resolution given by the heterodyne technique and was defined by the linewidth and stability of the Local Oscillator (LO). Response bandwidth was found to coincide with the detector's pulse width, which, in turn, could be controlled by the nanowire length. In addition, the system noise bandwidth was shown to be governed by the electronics/lab equipment, and the detector noise bandwidth is predicted to depend on its jitter. As have been demonstrated, a very small amount of the LO power (of the order of a few picowatts down to hundreds of femtowatts) was required for sufficient detection of the test signal, and eventual optimization could lead to further reduction of the LO power required, which would perfectly suit for the foreseen development of receiver matrices and the need for detection of ultra-low signals at a level of less-than-one-photon per second.

  17. VSiPMT a new photon detector

    Science.gov (United States)

    Di Capua, F.; Barbarino, G.; Barbato, F. C. T.; Campajola, L.; de Asmundis, R.; De Rosa, G.; Migliozzi, P.; Mollo, C. M.; Vivolo, D.

    2016-04-01

    Photon detection is a key factor to study many physical processes in several areas of fundamental physics research. Focusing the attention on photodetectors for particle astrophysics, the future experiments aimed at the study of very high-energy or extremely rare phenomena (e.g. dark matter, proton decay, neutrinos from astrophysical sources) will require additional improvements in linearity, gain, quantum efficiency and single photon counting capability. To meet the requirements of these class of experiments, we propose a new design for a modern hybrid photodetector: the VSiPMT (Vacuum Silicon PhotoMultiplier Tube). The idea is to replace the classical dynode chain of a PMT with a SiPM, which therefore acts as an electron detector and amplifier. The aim is to match the large sensitive area of a photocathode with the performances of the SiPM technology.

  18. VSiPMT a new photon detector

    Directory of Open Access Journals (Sweden)

    Di Capua F.

    2016-01-01

    Full Text Available Photon detection is a key factor to study many physical processes in several areas of fundamental physics research. Focusing the attention on photodetectors for particle astrophysics, the future experiments aimed at the study of very high-energy or extremely rare phenomena (e.g. dark matter, proton decay, neutrinos from astrophysical sources will require additional improvements in linearity, gain, quantum efficiency and single photon counting capability. To meet the requirements of these class of experiments, we propose a new design for a modern hybrid photodetector: the VSiPMT (Vacuum Silicon PhotoMultiplier Tube. The idea is to replace the classical dynode chain of a PMT with a SiPM, which therefore acts as an electron detector and amplifier. The aim is to match the large sensitive area of a photocathode with the performances of the SiPM technology.

  19. On the detection performance of semi-insulating GaAs detectors coupled to multichannel ASIC DX64 for X-ray imaging applications

    Energy Technology Data Exchange (ETDEWEB)

    Zat' ko, Bohumir [Institute of Electrical Engineering, Slovak Academy of Sciences, Dubravska cesta 9, SK-841 04 Bratislava (Slovakia)], E-mail: elekbzat@savba.sk; Dubecky, Frantisek [Institute of Electrical Engineering, Slovak Academy of Sciences, Dubravska cesta 9, SK-841 04 Bratislava (Slovakia); Scepko, Pavol [T and N System, Ltd., Severna 5, SK-974 01 Banska Bystrica (Slovakia); Grybos, Pawel [Department of Measurement and Instrumentation, AGH University of Science and Technology, Al. Mickiewicza 30, PL-30 059 Krakow (Poland); Mudron, Jan [MTC, a. s., Kuzmanyho 11, SK-031 01 Liptovsky Mikulas (Slovakia); Maj, Piotr; Szczygiel, Robert [Department of Measurement and Instrumentation, AGH University of Science and Technology, Al. Mickiewicza 30, PL-30 059 Krakow (Poland); Frollo, Ivan [Institute of Measurement Science, Slovak Academy of Sciences, Dubravska cesta 9, SK-841 04 Bratislava (Slovakia)

    2008-06-11

    Detectors based on semi-insulating (SI) GaAs show high detection efficiency and satisfactory energy resolution for modern X-ray digital imaging applications. This work deals with the performance of SI GaAs-based detectors coupled by wire bonding to the input of multichannel readout chip DX64 (technology CMOS 0.35 {mu}m). Detectors have circular Ti/Pt/Au multilayer Schottky blocking contacts with different diameters (0.75, 0.50, 0.30 and 0.20 mm). First results of operation of the used readout system in the single-photon counting regime are given.

  20. 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.

  1. 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.

  2. The Partition Noise Research of MCP Photon Counting Imager Detector Based on Vernier Anode%基于Vernier阳极微通道板光子计数探测器分割噪声

    Institute of Scientific and Technical Information of China (English)

    邢妍; 陈波; 金方圆; 王海峰; 张宏吉; 何玲平

    2016-01-01

    为消除微通道板光子计数探测器系统中电子噪声的干扰,研究了探测器分割噪声的来源,并提出利用COMSOL软件仿真计算分割噪声的方法.利用有限元方法对基于Vernier阳极探测器的成像过程进行三维建模,实现了一组5×5针孔阵列的模拟成像,计算出Vernier阳极分割噪声所产生的电子云质心位置的偏移量,验证了Vernier阳极探测器成像编码的正确性与仿真研究分割噪声的可行性.通过分析不同参量的阳极面板,利用数值拟合方法,得到电子云质心偏移量与阳极面板设计参量之间的关系.在固定面板参量的前提下,可以通过提高微通道板增益来有效降低分割噪声对质心位置偏移影响.

  3. Single photon source characterization with a superconducting single photon detector

    CERN Document Server

    Hadfield, R H; Miller, A J; Mirin, R P; Nam, S W; Schwall, R E; Stevens, M J; Gruber, Steven S.; Hadfield, Robert H.; Miller, Aaron J.; Mirin, Richard P.; Nam, Sae Woo; Schwall, Robert E.; Stevens, Martin J.

    2005-01-01

    Superconducting single photon detectors (SSPD) based on nanopatterned niobium nitride wires offer single photon counting at fast rates, low jitter, and low dark counts, from visible wavelengths well into the infrared. We demonstrate the first use of an SSPD, packaged in a commercial cryocooler, for single photon source characterization. The source is an optically pumped, microcavity-coupled InGaAs quantum dot, emitting single photons on demand at 902 nm. The SSPD replaces the second silicon Avalanche Photodiode (APD) in a Hanbury-Brown Twiss interferometer measurement of the source second-order correlation function, g (2) (tau). The detection efficiency of the superconducting detector system is >2 % (coupling losses included). The SSPD system electronics jitter is 170 ps, versus 550 ps for the APD unit, allowing the source spontaneous emission lifetime to be measured with improved resolution.

  4. Calibration of the Super-Kamiokande Detector

    CERN Document Server

    Abe, K; Iida, T; Iyogi, K; Kameda, J; Kishimoto, Y; Koshio, Y; Marti, Ll; Miura, M; Moriyama, S; Nakahata, M; Nakano, Y; Nakayama, S; Obayashi, Y; Sekiya, H; Shiozawa, M; Suzuki, Y; Takeda, A; Takenaga, Y; Tanaka, H; Tomura, T; Ueno, K; Wendell, R A; Yokozawa, T; Irvine, T J; Kaji, H; Kajita, T; Kaneyuki, K; Lee, K P; Nishimura, Y; Okumura, K; McLachlan, T; Labarga, L; Kearns, E; Raaf, J L; Stone, J L; Sulak, L R; Berkman, S; Tanaka, H A; Tobayama, S; Goldhaber, M; Bays, K; Carminati, G; Kropp, W R; Mine, S; Renshaw, A; Smy, M B; Sobel, H W; Ganezer, K S; Hill, J; Keig, W E; Jang, J S; Kim, J Y; Lim, I T; Hong, N; Akiri, T; Albert, J B; Himmel, A; Scholberg, K; Walter, C W; Wongjirad, T; Ishizuka, T; Tasaka, S; Learned, J G; Matsuno, S; Smith, S N; Hasegawa, T; Ishida, T; Ishii, T; Kobayashi, T; Nakadaira, T; Nakamura, K; Nishikawa, K; Oyama, Y; Sakashita, K; Sekiguchi, T; Tsukamoto, T; Suzuki, A T; Takeuchi, Y; Huang, K; Ieki, K; Ikeda, M; Kikawa, T; Kubo, H; Minamino, A; Murakami, A; Nakaya, T; Otani, M; Suzuki, K; Takahashi, S; Fukuda, Y; Choi, K; Itow, Y; Mitsuka, G; Miyake, M; Mijakowski, P; Tacik, R; Hignight, J; Imber, J; Jung, C K; Taylor, I; Yanagisawa, C; Idehara, Y; Ishino, H; Kibayashi, A; Mori, T; Sakuda, M; Yamaguchi, R; Yano, T; Kuno, Y; Kim, S B; Yang, B S; Okazawa, H; Choi, Y; Nishijima, K; Koshiba, M; Totsuka, Y; Yokoyama, M; Martens, K; Vagins, M R; Martin, J F; de Perio, P; Konaka, A; Wilking, M J; Chen, S; Heng, Y; Sui, H; Yang, Z; Zhang, H; Zhenwei, Y; Connolly, K; Dziomba, M; Wilkes, R J

    2013-01-01

    Procedures and results on hardware level detector calibration in Super-Kamiokande (SK) are presented in this paper. In particular, we report improvements made in our calibration methods for the experimental phase IV in which new readout electronics have been operating since 2008. The topics are separated into two parts. The first part describes the determination of constants needed to interpret the digitized output of our electronics so that we can obtain physical numbers such as photon counts and their arrival times for each photomultiplier tube (PMT). In this context, we developed an in-situ procedure to determine high-voltage settings for PMTs in large detectors like SK, as well as a new method for measuring PMT quantum efficiency and gain in such a detector. The second part describes the modeling of the detector in our Monte Carlo simulation, including in particular the optical properties of its water target and their variability over time. Detailed studies on the water quality are also presented. As a re...

  5. X-ray imaging with a silicon microstrip detector coupled to the RX64 ASIC

    Energy Technology Data Exchange (ETDEWEB)

    Baldazzi, G.; Bollini, D.; Cabal Rodriguez, A.E.; Dabrowski, W.; Diaz Garcia, A.; Gambaccini, M.; Giubellino, P.; Gombia, M.; Grybos, P.; Idzik, M.; Marzari-Chiesa, A.; Montano Zetina, L.M.; Prino, F.; Ramello, L. E-mail: ramello@to.infn.it; Sitta, M.; Swientek, K.; Taibi, A.; Tuffanelli, A.; Wheadon, R.; Wiacek, P

    2003-08-21

    A single photon counting X-ray imaging system, with possible applications to dual energy mammography and angiography, is presented. A silicon microstrip detector with 100 {mu}m pitch strips is coupled to RX64 ASICs, each of them including 64 channels of preamplifier, shaper, discriminator and scaler. The system has low noise, good spatial resolution and high counting rate capability. Results on energy resolution have been obtained with a fluorescence source and quasi-monochromatic X-rays beams. Preliminary images obtained with an angiographic phantom are presented.

  6. 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.

  7. 32 Bin Near-Infrared Time-Multiplexing Detector with Attojoule Single-Shot Energy Resolution

    CERN Document Server

    Eraerds, Patrick; Pomarico, Enrico; Sanguinetti, Bruno; Thew, Rob; Zbinden, Hugo

    2010-01-01

    We present two implementations of photon counting time-multiplexing detectors for near-infrared wavelengths, based on Peltier cooled InGaAs/InP avalanche photo diodes (APDs). A first implementation is motivated by practical considerations using only commercially available components. It features 16 bins, pulse repetition rates of up to 22 kHz and a large range of applicable pulse widths of up to 100 ns. A second implementation is based on rapid gating detectors, permitting deadtimes below 10 ns. This allows one to realize a high dynamic-range 32 bin detector, able to process pulse repetition rates of up to 6 MHz for pulse width of up to 200 ps. Analysis of the detector response at 16.5% detection efficiency, reveals a single-shot energy resolution on the attojoule level.

  8. 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.

  9. Versatile Wideband Balanced Detector for Quantum Optical Homodyne Tomography

    CERN Document Server

    Kumar, Ranjeet; MacRae, Andrew; Cairns, E; Huntington, E H; Lvovsky, A I

    2011-01-01

    We present a comprehensive theory and an easy to follow method for the design and construction of a wideband homodyne detector for time-domain quantum measurements. We show how one can evaluate the performance of a detector in a specific time-domain experiment based on electronic spectral characteristic of that detector. We then present and characterize a high-performance detector constructed using inexpensive, commercially available components such as low-noise high-speed operational amplifiers and high-bandwidth photodiodes. Our detector shows linear behavior up to a level of over 13 dB clearance between shot noise and electronic noise, in the range from DC to 100 MHz. The detector can be used for measuring quantum optical field quadratures both in the continuous-wave and pulsed regimes with pulse repetition rates up to about 250 MHz.

  10. Applications of pixellated GaAs X-ray detectors in a synchrotron radiation beam

    CERN Document Server

    Watt, J; Campbell, M; Mathieson, K; Mikulec, B; O'Shea, V; Passmore, M S; Schwarz, C; Smith, K M; Whitehill, C

    2001-01-01

    Hybrid semiconductor pixel detectors are being investigated as imaging devices for radiography and synchrotron radiation beam applications. Based on previous work in the CERN RD19 and the UK IMPACT collaborations, a photon counting GaAs pixel detector (PCD) has been used in an X-ray powder diffraction experiment. The device consists of a 200 mu m thick SI-LEC GaAs detector patterned in a 64*64 array of 170 mu m pitch square pixels, bump-bonded to readout electronics operating in single photon counting mode. Intensity peaks in the powder diffraction pattern of KNbO/sub 3/ have been resolved and compared with results using the standard scintillator, and a PCD predecessor (the Omega 3). The PCD shows improved speed, dynamic range, 2-D information and comparable spatial resolution to the standard scintillator based systems. It also overcomes the severe dead time limitations of the Omega 3 by using a shutter based acquisition mode. A brief demonstration of the possibilities of the system for dental radiography and...

  11. Applications of pixellated GaAs X-ray detectors in a synchrotron radiation beam

    Energy Technology Data Exchange (ETDEWEB)

    Watt, J. E-mail: j.watt@physics.gla.ac.uk; Bates, R.; Campbell, M.; Mathieson, K.; Mikulec, B.; O' Shea, V.; Passmore, M-S.; Schwarz, C.; Smith, K.M.; Whitehill, C

    2001-03-11

    Hybrid semiconductor pixel detectors are being investigated as imaging devices for radiography and synchrotron radiation beam applications. Based on previous work in the CERN RD19 and the UK IMPACT collaborations, a photon counting GaAs pixel detector (PCD) has been used in an X-ray powder diffraction experiment. The device consists of a 200 {mu}m thick SI-LEC GaAs detector patterned in a 64x64 array of 170 {mu}m pitch square pixels, bump-bonded to readout electronics operating in single photon counting mode. Intensity peaks in the powder diffraction pattern of KNbO{sub 3} have been resolved and compared with results using the standard scintillator, and a PCD predecessor (the {omega}3). The PCD shows improved speed, dynamic range, 2-D information and comparable spatial resolution to the standard scintillator based systems. It also overcomes the severe dead time limitations of the {omega}3 by using a shutter based acquisition mode. A brief demonstration of the possibilities of the system for dental radiography and image processing are given, showing a marked reduction in patient dose and dead time compared with film.

  12. Photon-statistics-based classical ghost imaging with one single detector.

    Science.gov (United States)

    Kuhn, Simone; Hartmann, Sébastien; Elsäßer, Wolfgang

    2016-06-15

    We demonstrate a novel ghost imaging (GI) scheme based on one single-photon-counting detector with subsequent photon statistics analysis. The key idea is that instead of measuring correlations between the object and reference beams such as in standard GI schemes, the light of the two beams is superimposed. The photon statistics analysis of this mixed light allows us to determine the photon number distribution as well as to calculate the central second-order correlation coefficient. The image information is obtained as a function of the spatial resolution of the reference beam. The performance of this photon-statistics-based GI system with one single detector (PS-GI) is investigated in terms of visibility and resolution. Finally, the knowledge of the complete photon statistics allows easy access to higher correlation coefficients such that we are able to perform here third- and fourth-order GI. The PS-GI concept can be seen as a complement to already existing GI technologies thus enabling a broader dissemination of GI as a superior metrology technique, paving the road for new applications in particular with advanced photon counting detectors.

  13. Submillisecond X-ray photon correlation spectroscopy from a pixel array detector with fast dual gating and no readout dead-time.

    Science.gov (United States)

    Zhang, Qingteng; Dufresne, Eric M; Grybos, Pawel; Kmon, Piotr; Maj, Piotr; Narayanan, Suresh; Deptuch, Grzegorz W; Szczygiel, Robert; Sandy, Alec

    2016-05-01

    Small-angle scattering X-ray photon correlation spectroscopy (XPCS) studies were performed using a novel photon-counting pixel array detector with dual counters for each pixel. Each counter can be read out independently from the other to ensure there is no readout dead-time between the neighboring frames. A maximum frame rate of 11.8 kHz was achieved. Results on test samples show good agreement with simple diffusion. The potential of extending the time resolution of XPCS beyond the limit set by the detector frame rate using dual counters is also discussed.

  14. Submillisecond X-ray photon correlation spectroscopy from a pixel array detector with fast dual gating and no readout dead-time

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qingteng; Dufresne, Eric M.; Grybos, Pawel; Kmon, Piotr; Maj, Piotr; Narayanan, Suresh; Deptuch, Grzegorz W.; Szczygiel, Robert; Sandy, Alec

    2016-04-19

    Small-angle scattering X-ray photon correlation spectroscopy (XPCS) studies were performed using a novel photon-counting pixel array detector with dual counters for each pixel. Each counter can be read out independently from the other to ensure there is no readout dead-time between the neighboring frames. A maximum frame rate of 11.8 kHz was achieved. Results on test samples show good agreement with simple diffusion. The potential of extending the time resolution of XPCS beyond the limit set by the detector frame rate using dual counters is also discussed.

  15. 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...

  16. 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

  17. Imaging characteristics of the Extreme Ultraviolet Explorer microchannel plate detectors

    Science.gov (United States)

    Vallerga, J. V.; Kaplan, G. C.; Siegmund, O. H. W.; Lampton, M.; Malina, R. F.

    1989-01-01

    The Extreme Ultraviolet Explorer (EUVE) satellite will conduct an all-sky survey over the wavelength range from 70 A to 760 A using four grazing-incidence telescopes and seven microchannel-plate (MCP) detectors. The imaging photon-counting MCP detectors have active areas of 19.6 cm2. Photon arrival position is determined using a wedge-and-strip anode and associated pulse-encoding electronics. The imaging characteristics of the EUVE flight detectors are presented including image distortion, flat-field response, and spatial differential nonlinearity. Also included is a detailed discussion of image distortions due to the detector mechanical assembly, the wedge-and-strip anode, and the electronics. Model predictions of these distortions are compared to preflight calibration images which show distortions less than 1.3 percent rms of the detector diameter of 50 mm before correction. The plans for correcting these residual detector image distortions to less than 0.1 percent rms are also presented.

  18. Study of timing performance of Silicon Photomultiplier and application for a Cherenkov detector

    CERN Document Server

    Ahmed, G S M; Marton, J; Suzuki, K

    2010-01-01

    Silicon photomultipliers are very versatile photo detectors due to their high photon detection efficiency, fast response, single photon counting capability, high amplification, and their insensitivity to magnetic fields. At our institute we are studying the performance of these photo detectors at various operating conditions. On the basis of the experience in the laboratory we built a prototype of a timing Cherenkov detector consisting of a quartz radiator with two $3\\times 3$ mm$^2$ MPPCs S10362-33-100C from Hamamatsu Photonics as photodetectors. The MPPC sensors were operated with Peltier cooling to minimize thermal noise and to avoid gain drifts. The test measurements at the DA$\\Phi$NE Beam-Test Facility (BTF) at the Laboratori Nazionali di Frascati (LNF) with pulsed 490 MeV electrons and the results on timing performance with Cherenkov photons are presented.

  19. Development of the EUV detector for the BepiColombo mission

    Science.gov (United States)

    Yoshioka, K.; Hikosaka, K.; Murakami, G.; Yoshikawa, I.; Yamazaki, A.; Nozawa, H.

    An ultraviolet spectrometer, PHEBUS (Probing of Hermean Exosphere by Ultraviolet Spectroscopy) that is loaded onto the Mercury Planetary Orbiter in the BepiColombo mission is under development. The instrument, basically consisting of two spectrophotometers (EUV: 50 150 nm, FUV: 145 330 nm) and one scanning mirror, aims at measuring emission lines from molecules, atoms and ions present in the tenuous atmosphere of Mercury. The detectors employ microchannel plates as 2-D photon-counting devices. In order to enhance the quantum detection efficiencies, the surface of the top microchannel plates of EUV detector is covered with photocathode. This method enables us to identify weak atmospheric signatures such as neon (73.5 nm) and argon (104.8 nm), which could not be detected with conventional detector systems. This paper presents measurements of the performance characteristics of potassium bromide and esium iodide photocathodes, which have been evaluated for use in the EUV channel.

  20. The effect of magnetic field on the intrinsic detection efficiency of superconducting single-photon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Renema, J. J.; Rengelink, R. J.; Komen, I.; Wang, Q.; Kes, P.; Aarts, J.; Exter, M. P. van; Dood, M. J. A. de [Huygens-Kamerlingh Onnes Lab, Leiden University, Niels Bohrweg 2, 2333 CA Leiden (Netherlands); Gaudio, R.; Hoog, K. P. M. op ' t; Zhou, Z.; Fiore, A. [COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Sahin, D. [COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Centre for Quantum Photonics, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Driessen, E. F. C. [Univ. Grenoble Alpes, INAC-SPSMS, 38000 Grenoble (France); CEA, INAC-SPSMS, 38000 Grenoble (France)

    2015-03-02

    We experimentally investigate the effect of a magnetic field on photon detection in superconducting single-photon detectors (SSPDs). At low fields, the effect of a magnetic field is through the direct modification of the quasiparticle density of states of the superconductor, and magnetic field and bias current are interchangeable, as is expected for homogeneous dirty-limit superconductors. At the field where a first vortex enters the detector, the effect of the magnetic field is reduced, up until the point where the critical current of the detector starts to be determined by flux flow. From this field on, increasing the magnetic field does not alter the detection of photons anymore, whereas it does still change the rate of dark counts. This result points at an intrinsic difference in dark and photon counts, and also shows that no enhancement of the intrinsic detection efficiency of a straight SSPD wire is achievable in a magnetic field.

  1. Free-space-coupled superconducting nanowire single-photon detectors for infrared optical communications.

    Science.gov (United States)

    Bellei, Francesco; Cartwright, Alyssa P; McCaughan, Adam N; Dane, Andrew E; Najafi, Faraz; Zhao, Qingyuan; Berggren, Karl K

    2016-02-22

    This paper describes the construction of a cryostat and an optical system with a free-space coupling efficiency of 56.5% ± 3.4% to a superconducting nanowire single-photon detector (SNSPD) for infrared quantum communication and spectrum analysis. A 1K pot decreases the base temperature to T = 1.7 K from the 2.9 K reached by the cold head cooled by a pulse-tube cryocooler. The minimum spot size coupled to the detector chip was 6.6 ± 0.11 µm starting from a fiber source at wavelength, λ = 1.55 µm. We demonstrated photon counting on a detector with an 8 × 7.3 µm2 area. We measured a dark count rate of 95 ± 3.35 kcps and a system detection efficiency of 1.64% ± 0.13%. We explain the key steps that are required to improve further the coupling efficiency.

  2. ASICs in nanometer and 3D technologies for readout of hybrid pixel detectors

    Science.gov (United States)

    Maj, Piotr; Grybos, Pawel; Kmon, Piotr; Szczygiel, Robert

    2013-07-01

    Hybrid pixel detectors working in a single photon counting mode are very attractive solutions for material science and medical X-ray imaging applications. Readout electronics of these detectors has to match the geometry of pixel detectors with an area of readout channel of 100 μm × 100 μm (or even less) and very small power consumption (a few tens of μW). New solutions of readout ASICs are going into directions of better spatial resolutions, higher data throughput and more advanced functionality. We report on the design and measurement results of two pixel prototype ASICs in nanometer technology and 3D technology which offer fast signal processing, low noise performance and advanced functionality per single readout pixel cell.

  3. The ATLAS tracker Pixel detector for HL-LHC

    CERN Document Server

    Gemme, Claudia; The ATLAS collaboration

    2017-01-01

    The high luminosity upgrade of the LHC (HL-LHC) in 2026 will provide new challenges to the ATLAS tracker. The current Inner Detector will be replaced with a whole silicon tracker which will consist of a five barrel layer Pixel detector surrounded by a four barrel layer Strip detector. The expected high radiation levels are requiring the development of upgraded silicon sensors as well as new a front-end chip. The dense tracking environment will require finer granularity detectors. The data rates will require new technologies for high bandwidth data transmission and handling. The current status of the HL-LHC ATLAS Pixel detector developments as well as the various layout options are reviewed.

  4. Saturation effects in heterodyne detection with Geiger-mode InGaAs avalanche photodiode detector arrays.

    Science.gov (United States)

    Luu, Jane X; Jiang, Leaf A

    2006-06-01

    We report, to the best of our knowledge, the first demonstration of heterodyne detection of a glint target using an InGaAs avalanche photodiode detector (APD) array in the Geiger mode. Due to the finite number of pixels, all such photon-counting arrays necessarily suffer from saturation effects. At large photon fluxes, saturation of the APD degrades the Doppler frequency resolution and the signal-to-noise ratio (SNR). We derive analytical expressions for the Doppler resolution and SNR, taking saturation effects into account. The optimal local oscillator power can be obtained numerically from the SNR expression.

  5. Advances in X-ray detectors for clinical and preclinical Computed Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Panetta, Daniele

    2016-02-11

    Computed tomography (CT) is a non-invasive X-ray diagnostic technique that allows reconstructing cross sections of a patient's body, providing detailed information about structure and anatomy of organs and, in some extent, also about their functionality. Since the development of the first CT scanner for clinical use in the ‘70s, several improvements especially in solid-state X-ray detector technology with growing detection efficiency and fast response have led to the current configuration of modern ultra-fast, low dose whole body CT scanners. Such developments brought great advantages in the clinical settings in terms of image quality, dose effectiveness, imaging throughput, but also extending considerably the field of clinical application that were initially foreseen. Parallel to the roadmap of clinical CT technology, dedicated systems for high-resolution preclinical CT (or micro-CT) have seen a considerable growth in the last two decades, taking advantage of the modern technology of high granularity flat-panel X-ray detectors (FPD). This article aims at reviewing the milestones of the evolution of X-ray detector technology that have traced the roadmap of development of CT and micro-CT. An outlook of the current and future trends on energy resolved clinical and preclinical CT with photon counting detectors will be also given. - Highlights: • Evolution of X-ray detectors has marked the roadmap of CT technology development. • Digital flat-panel detectors have lead to the introduction of the CBCT concept. • CBCT systems with resolution below 0.1 mm are widely used in the preclinical field. • Photon-counting spectral imaging is foreseen to dominate the future of CT roadmap.

  6. Single-Photon-Sensitive HgCdTe Avalanche Photodiode Detector

    Science.gov (United States)

    Huntington, Andrew

    2013-01-01

    The purpose of this program was to develop single-photon-sensitive short-wavelength infrared (SWIR) and mid-wavelength infrared (MWIR) avalanche photodiode (APD) receivers based on linear-mode HgCdTe APDs, for application by NASA in light detection and ranging (lidar) sensors. Linear-mode photon-counting APDs are desired for lidar because they have a shorter pixel dead time than Geiger APDs, and can detect sequential pulse returns from multiple objects that are closely spaced in range. Linear-mode APDs can also measure photon number, which Geiger APDs cannot, adding an extra dimension to lidar scene data for multi-photon returns. High-gain APDs with low multiplication noise are required for efficient linear-mode detection of single photons because of APD gain statistics -- a low-excess-noise APD will generate detectible current pulses from single photon input at a much higher rate of occurrence than will a noisy APD operated at the same average gain. MWIR and LWIR electron-avalanche HgCdTe APDs have been shown to operate in linear mode at high average avalanche gain (M > 1000) without excess multiplication noise (F = 1), and are therefore very good candidates for linear-mode photon counting. However, detectors fashioned from these narrow-bandgap alloys require aggressive cooling to control thermal dark current. Wider-bandgap SWIR HgCdTe APDs were investigated in this program as a strategy to reduce detector cooling requirements.

  7. CIX - A Detector for Spectral Enhanced X-ray Imaging by Simultaneous Counting and Integrating

    CERN Document Server

    Krüger, H; Kraft, E; Wermes, N; Fischer, P; Peric, I; Herrmann, C; Overdick, M; Rütten, W

    2008-01-01

    A hybrid pixel detector based on the concept of simultaneous charge integration and photon counting will be presented. The second generation of a counting and integrating X-ray prototype CMOS chip (CIX) has been operated with different direct converting sensor materials (CdZnTe and CdTe) bump bonded to its 8x8 pixel matrix. Photon counting devices give excellent results for low to medium X-ray fluxes but saturate at high rates while charge integration allows the detection of very high fluxes but is limited at low rates by the finite signal to noise ratio. The combination of both signal processing concepts therefore extends the resolvable dynamic range of the X-ray detector. In addition, for a large region of the dynamic range, where counter and integrator operate simultaneously, the mean energy of the detected X-ray spectrum can be calculated. This spectral information can be used to enhance the contrast of the X-ray image. The advantages of the counting and integrating signal processing concept and the perfo...

  8. Adaptive Depth Imaging with Single-Photon Detectors

    CERN Document Server

    He, Weiji; Lin, Jie; Shen, Shanshan; Chen, Qian; Gu, Guohua; Zhou, Beibei; Zhang, Ping

    2016-01-01

    For active optical imaging, the use of single-photon detectors could greatly improve the detection sensitivity of the system. However in low light-level, traditional maximum-likelihood based imaging method needs long acquisition time to capture clear three-dimensional (3D) image. To tackle this problem, we present a novel imaging method for depth estimate, which can obtain the accurate depth image in a short acquisition time. We exploit the temporal correlations of signal and avoid building the photon-count histogram of the maximum likelihood depth estimate. Our method can efficiently distinguish signal from noise and adaptively change the dwell time of each pixel. The experiment results demonstrate that we can fast obtain the accurate depth image despite the existence of strong background noise.

  9. Projection x-ray imaging with photon energy weighting: experimental evaluation with a prototype detector.

    Science.gov (United States)

    Shikhaliev, Polad M

    2009-08-21

    The signal-to-noise ratio (SNR) in x-ray imaging can be increased using a photon counting detector which could allow for rejecting electronics noise and for weighting x-ray photons according to their energies. This approach, however, was not feasible for a long time because photon counting x-ray detectors with very high count rates, good energy resolution and a large number of small pixels were required. These problems have been addressed with the advent of new detector materials, fast readout electronics and powerful computers. In this work, we report on the experimental evaluation of projection x-ray imaging with a photon counting cadmium-zinc-telluride (CZT) detector with energy resolving capabilities. The detector included two rows of pixels with 128 pixels per row with 0.9 x 0.9 mm(2) pixel size, and a 2 Mcount pixel(-1) s(-1) count rate. The x-ray tube operated at 120 kVp tube voltage with 2 mm Al-equivalent inherent filtration. The x-ray spectrum was split into five regions, and five independent x-ray images were acquired at a time. These five quasi-monochromatic x-ray images were used for x-ray energy weighting and material decomposition. A tissue-equivalent phantom was used including contrast elements simulating adipose, calcifications, iodine and air. X-ray energy weighting improved the SNR of calcifications and iodine by a factor of 1.32 and 1.36, respectively, as compared to charge integrating. Material decomposition was performed by dual energy subtraction. The low- and high-energy images were generated in the energy ranges of 25-60 keV and 60-120 keV, respectively, by combining five monochromatic image data into two. X-ray energy weighting was applied to low- and high-energy images prior to subtraction, and this improved the SNR of calcifications and iodine in dual energy subtracted images by a factor of 1.34 and 1.25, respectively, as compared to charge integrating. The detector energy resolution, spatial resolution, linearity, count rate, noise and

  10. CZT detector in multienergy x-ray imaging with different pixel sizes and pitches: Monte Carlo simulation studies

    Science.gov (United States)

    Choi, Yu-Na; Kim, Hee-Joung; Cho, Hyo-Min; Lee, Chang-Lae; Park, Hye-Suk; Kim, Dae-Hong; Lee, Seung-Wan; Ryu, Hyun-Ju

    2011-03-01

    A photon counting detector based on semiconductor materials is a very promising approach for x-ray imaging. Cadmium zinc telluride (CZT) semiconductor has a high atomic number which results in higher absorption coefficients for x-rays. However, the CZT detectors exhibit several problems with hole trapping and charge sharing. Charge sharing occurs due to diffusion of charge and characteristic x-ray escape and scattered x-rays in the detectors. In this study, we evaluated the effect of interaction with CZT detector using Monte Carlo simulations. To demonstrate the effectiveness of CZT detector in clinical application, we reported confirmation of CNR improvement in K-edge images, and material decomposition using energy selective windows. X-ray energy spectrum acquired at 120 kVp tube voltage and 2 mm Al filtration and 10 cm added water phantom in the x-ray beam. Geant4 Application for Tomographic Emission (GATE) version 6.0 was used for a CZT crystal with size of 10x10 mm2 and thickness of 4 mm. The detector pixel with sizes of 0.09x0.09, 0.45x0.45, and 0.90x0.90 mm2 were simulated. For all pixel sizes, the x-ray spectra of the simulations were distorted towards the lower energy region. Because the characteristic x-rays add counts in the range of 20-40 keV. The magnitude of this deterioration is substantial for small pixel sizes. However, we demonstrated that the distortion of spectrum does not greatly affect the x-ray imaging. The GATE simulation model and these results may be used as a basis of development of energy-resolved photon counting x-ray detector. We believe that the CZT detector may enhance the detectability of multi-energy x-ray imaging.

  11. Simulation and Analysis of Router Buffer Requirements in High Bandwidth-Delay Networks%高带宽延迟网络中路由器缓存需求的仿真分析

    Institute of Scientific and Technical Information of China (English)

    王建新; 李春泉; 黄家玮

    2009-01-01

    In order to meet the requirement for router buffer size in high bandwidth-delay networks, five typical buffer-sizing methods based on the TCP model are analyzed via the NS2 simulation, and the effects of various high-speed TCP protocols and active queue management (AQM) mechanisms on the buffer-sizing methods in high bandwidth-delay networks are discussed in detail. Simulated results show that: (1) the buffer-sizing methods based on different assumptions adapt to different network environments; (2) the validity of the existing cache mechanisms depends on the ratio of the bandwidth-delay product to the flow number; and (3) when high-speed TCP protocols and AQM mechanisms are used in high bandwidth-delay networks, the buffer size is greatly reduced.%文中针对当今高带宽延迟网络下路由器缓存大小的需求问题,通过NS2仿真实验,对基于TCP协议模型的5种典型的缓存设置方法展开研究,着重分析了在高带宽延迟网络下各种高速TCP协议和主动队列管理(AQM)机制对各种缓存设置方法的影响.仿真实验表明:基于不同假设前提的缓存设置方法适应于不同的网络负载环境;缓存机制的选择取决于网络带宽延迟乘积与流数的比值;在高带宽延迟网络下,当采用高速TCP协议和AQM机制时,缓存需求可以大大减小.

  12. 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.

  13. Preliminary test of an imaging probe for nuclear medicine using hybrid pixel detectors

    CERN Document Server

    Bertolucci, Ennio; Mettivier, G; Montesi, M C; Russo, P

    2002-01-01

    We are investigating the feasibility of an intraoperative imaging probe for lymphoscintigraphy with Tc-99m tracer, for sentinel node radioguided surgery, using the Medipix series of hybrid detectors coupled to a collimator. These detectors are pixelated semiconductor detectors bump-bonded to the Medipix1 photon counting read-out chip (64x64 pixel, 170 mu m pitch) or to the Medipix2 chip (256x256 pixel, 55 mu m pitch), developed by the European Medipix collaboration. The pixel detector we plan to use in the final version of the probe is a semi-insulating GaAs detector or a 1-2 mm thick CdZnTe detector. For the preliminary tests presented here, we used 300-mu m thick silicon detectors, hybridized via bump-bonding to the Medipix1 chip. We used a tungsten parallel-hole collimator (7 mm thick, matrix array of 64x64 100 mu m circular holes with 170 mu m pitch), and a 22, 60 and 122 keV point-like (1 mm diameter) radioactive sources, placed at various distances from the detector. These tests were conducted in order ...

  14. Impact of detector geometry for compressive fan beam snapshot coherent scatter imaging

    Science.gov (United States)

    Hassan, Mehadi; Holmgren, Andrew; Greenberg, Joel A.; Odinaka, Ikenna; Brady, David

    2016-05-01

    Previous realizations of coded-aperture X-ray diffraction tomography (XRDT) techniques based on pencil beams image one line through an object via a single measurement but require raster scanning the object in multiple dimensions. Fan beam approaches are able to image the spatial extent of the object while retaining the ability to do material identification. Building on these approaches we present our system concept and geometry of combining a fan beam with energy sensitive/photon counting detectors and a coded aperture to capture both spatial and spectral information about an object at each voxel. Using our system we image slices via snapshot measurements for four different detector configurations and compare their results.

  15. High Precision Stokes Polarimetry for Scattering Light using Wide Dynamic Range Intensity Detector

    Directory of Open Access Journals (Sweden)

    Shibata Shuhei

    2015-01-01

    Full Text Available This paper proposes a Stokes polarimetry for scattering light from a sample surface. To achieve a high accuracy measurement two approaches of an intensity detector and analysis algorism of a Stokes parameter were proposed. The dynamic range of this detector can achieve up to 1010 by combination of change of neutral-density (ND filters having different density and photon counting units. Stokes parameters can be measured by dual rotating of a retarder and an analyzer. The algorism of dual rotating polarimeter can be calibrated small linear diattenuation and linear retardance error of the retarder. This system can measured Stokes parameters from −20° to 70° of its scattering angle. It is possible to measure Stokes parameters of scattering of dust and scratch of optical device with high precision. This paper shows accuracy of this system, checking the polarization change of scattering angle and influence of beam size.

  16. Optically sensitive Medipix2 detector for adaptive optics wavefront sensing

    CERN Document Server

    Vallerga, John; Tremsina, Anton; Siegmund, Oswald; Mikulec, Bettina; Clark, Allan G; CERN. Geneva

    2005-01-01

    A new hybrid optical detector is described that has many of the attributes desired for the next generation adaptive optics (AO) wavefront sensors. The detector consists of a proximity focused microchannel plate (MCP) read out by multi-pixel application specific integrated circuit (ASIC) chips developed at CERN ("Medipix2") with individual pixels that amplify, discriminate and count input events. The detector has 256 x 256 pixels, zero readout noise (photon counting), can be read out at 1 kHz frame rates and is abutable on 3 sides. The Medipix2 readout chips can be electronically shuttered down to a temporal window of a few microseconds with an accuracy of 10 ns. When used in a Shack-Hartmann style wavefront sensor, a detector with 4 Medipix chips should be able to centroid approximately 5000 spots using 7 x 7 pixel sub-apertures resulting in very linear, off-null error correction terms. The quantum efficiency depends on the optical photocathode chosen for the bandpass of interest.

  17. Imaging with polycrystalline mercuric iodide detectors using VLSI readout

    Energy Technology Data Exchange (ETDEWEB)

    Turchetta, R.; Dulinski, W.; Husson, D.; Riester, J.L.; Schieber, M.; Zuck, A.; Melekhov, L.; Saado, Y.; Hermon, H.; Nissenbaum, J

    1999-06-01

    Potentially low cost and large area polycrystalline mercuric iodide room-temperature radiation detectors, with thickness of 100-600 {mu}m have been successfully tested with dedicated low-noise, low-power mixed signal VLSI electronics which can be used for compact, imaging solutions. The detectors are fabricated by depositing HgI{sub 2} directly on an insulating substrate having electrodes in the form of microstrips and pixels with an upper continuous electrode. The deposition is made either by direct evaporation or by screen printing HgI{sub 2} mixed with glue such as Poly-Vinyl-Butiral. The properties of these first-generation detectors are quite uniform from one detector to another. Also for each single detector the response is quite uniform and no charge loss in the inter-electrode space have been detected. Because of the low cost and of the polycrystallinity, detectors can be potentially fabricated in any size and shape, using standard ceramic technology equipment, which is an attractive feature where low cost and large area applications are needed. The detectors which act as radiation counters have been tested with a beta source as well as in a high-energy beam of 100 GeV muons at CERN, connected to VLSI, low noise electronics. Charge collection efficiency and uniformity have been studied. The charge is efficiently collected even in the space between strips indicating that fill factors of 100% could be reached in imaging applications with direct detection of radiation. Single photon counting capability is reached with VLSI electronics. These results show the potential of this material for applications demanding position sensitive, radiation resistant, room-temperature operating radiation detectors, where position resolution is essential, as it can be found in some applications in high-energy physics, nuclear medicine and astrophysics.

  18. A micron resolution optical scanner for characterization of silicon detectors

    Science.gov (United States)

    Shukla, R. A.; Dugad, S. R.; Garde, C. S.; Gopal, A. V.; Gupta, S. K.; Prabhu, S. S.

    2014-02-01

    The emergence of high position resolution (˜10 μm) silicon detectors in recent times have highlighted the urgent need for the development of new automated optical scanners of micron level resolution suited for characterizing microscopic features of these detectors. More specifically, for the newly developed silicon photo-multipliers (SiPM) that are compact, possessing excellent photon detection efficiency with gain comparable to photo-multiplier tube. In a short time, since their invention the SiPMs are already being widely used in several high-energy physics and astrophysics experiments as the photon readout element. The SiPM is a high quantum efficiency, multi-pixel photon counting detector with fast timing and high gain. The presence of a wide variety of photo sensitive silicon detectors with high spatial resolution requires their performance evaluation to be carried out by photon beams of very compact spot size. We have designed a high resolution optical scanner that provides a monochromatic focused beam on a target plane. The transverse size of the beam was measured by the knife-edge method to be 1.7 μm at 1 - σ level. Since the beam size was an order of magnitude smaller than the typical feature size of silicon detectors, this optical scanner can be used for selective excitation of these detectors. The design and operational details of the optical scanner, high precision programmed movement of target plane (0.1 μm) integrated with general purpose data acquisition system developed for recording static and transient response photo sensitive silicon detector are reported in this paper. Entire functionality of scanner is validated by using it for selective excitation of individual pixels in a SiPM and identifying response of active and dead regions within SiPM. Results from these studies are presented in this paper.

  19. A micron resolution optical scanner for characterization of silicon detectors.

    Science.gov (United States)

    Shukla, R A; Dugad, S R; Garde, C S; Gopal, A V; Gupta, S K; Prabhu, S S

    2014-02-01

    The emergence of high position resolution (∼10 μm) silicon detectors in recent times have highlighted the urgent need for the development of new automated optical scanners of micron level resolution suited for characterizing microscopic features of these detectors. More specifically, for the newly developed silicon photo-multipliers (SiPM) that are compact, possessing excellent photon detection efficiency with gain comparable to photo-multiplier tube. In a short time, since their invention the SiPMs are already being widely used in several high-energy physics and astrophysics experiments as the photon readout element. The SiPM is a high quantum efficiency, multi-pixel photon counting detector with fast timing and high gain. The presence of a wide variety of photo sensitive silicon detectors with high spatial resolution requires their performance evaluation to be carried out by photon beams of very compact spot size. We have designed a high resolution optical scanner that provides a monochromatic focused beam on a target plane. The transverse size of the beam was measured by the knife-edge method to be 1.7 μm at 1 - σ level. Since the beam size was an order of magnitude smaller than the typical feature size of silicon detectors, this optical scanner can be used for selective excitation of these detectors. The design and operational details of the optical scanner, high precision programmed movement of target plane (0.1 μm) integrated with general purpose data acquisition system developed for recording static and transient response photo sensitive silicon detector are reported in this paper. Entire functionality of scanner is validated by using it for selective excitation of individual pixels in a SiPM and identifying response of active and dead regions within SiPM. Results from these studies are presented in this paper.

  20. Simulating the Counting Mechanism of PILATUS2 and PILATUS3 Detectors for Improved Count Rate Corrections

    Science.gov (United States)

    Trueb, P.; Sobott, B. A.; Schnyder, R.; Loeliger, T.; Schneebeli, M.; Kobas, M.; Rassool, R. P.; Peake, D. J.; Broennimann, C.

    2013-03-01

    PILATUS systems are well established as X-ray detectors at most synchrotrons. Their single photon counting capability ensures precise measurements, but introduces a short dead time after each hit, which becomes significant for photon rates above a million per second and pixel. The resulting loss in the number of counted photons can be corrected for by applying corresponding rate correction factors. This article presents a Monte-Carlo simulation, which computes the correction factors taking into account the detector settings as well as the time structure of the X-ray beam at the synchrotron. For the PILATUS2 detector series the simulation shows good agreement with experimentally determined correction factors for various detector settings at different synchrotrons. The application of more accurate rate correction factors will improve the X-ray data quality at high photon fluxes. Furthermore we report on the simulation of the rate correction factors for the new PILATUS3 systems. The successor of the PILATUS2 detector avoids the paralysation of the counter, and allows for measurements up to a rate of ten million photons per second and pixel. For fast detector settings the simulation is capable of reproducing the data within one to two percent at an incoming photon rate of one million per second and pixel.