WorldWideScience

Sample records for counting x-ray detectors

  1. 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).

  2. 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.

  3. 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.

  4. 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.

  5. 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...

  6. An automatic attenuator device for x-ray detectors at high counting rate

    Science.gov (United States)

    Alvarez, J.; Paiser, E.; Capitan, M. J.

    2002-07-01

    In this article we describe an attenuator device for reducing/controlling the pulse detector counting losses at a high counting rate. The electronics are based on a direct measure of the detector dead time from the analog output signal at the end of the detection chain. Taking into account this parameter the attenuator device decides to reduce/enhance the number of photons that arrive at the detector by inserting/extracting the necessary number of attenuation foils in the x-ray beam path. In that way the number of events in the incoming signal are reduced and the "apparent dynamic range" of the detector is increased.

  7. 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)

  8. 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)

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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 (...

  14. 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.

  15. Characterization of the imaging performance of the simultaneously counting and integrating X-ray detector CIX

    Energy Technology Data Exchange (ETDEWEB)

    Fink, Johannes

    2010-01-15

    The CIX detector is a direct converting hybrid pixel detector designed for medical X-ray imaging applications. Its de ning feature is the simultaneous operation of a photon counter as well as an integrator in every pixel cell. This novel approach o ers a dynamic range of more than five orders of magnitude, as well as the ability to directly obtain the average photon energy from the measured data. Several CIX 0.2 ASICs have been successfully connected to CdTe, CdZnTe and Si sensors. These detector modules were tested with respect to the imaging performance of the simultaneously counting and integrating concept under X-ray irradiation. Apart from a characterization of the intrinsic benefits of the CIX concept, the sensor performance was also investigated. Here, the two parallel signal processing concepts offer valuable insights into material related effects like polarization and temporal response. The impact of interpixel coupling effects like charge-sharing, Compton scattering and X-ray fluorescence was evaluated through simulations and measurements. (orig.)

  16. 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.

  17. 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.

  18. 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.

  19. 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.

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

    OpenAIRE

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

    2011-01-01

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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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...

  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. 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....

  12. 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.

  13. 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.

  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. Semiconductor X-ray detectors

    CERN Document Server

    Lowe, Barrie Glyn

    2014-01-01

    Identifying and measuring the elemental x-rays released when materials are examined with particles (electrons, protons, alpha particles, etc.) or photons (x-rays and gamma rays) is still considered to be the primary analytical technique for routine and non-destructive materials analysis. The Lithium Drifted Silicon (Si(Li)) X-Ray Detector, with its good resolution and peak to background, pioneered this type of analysis on electron microscopes, x-ray fluorescence instruments, and radioactive source- and accelerator-based excitation systems. Although rapid progress in Silicon Drift Detectors (SDDs), Charge Coupled Devices (CCDs), and Compound Semiconductor Detectors, including renewed interest in alternative materials such as CdZnTe and diamond, has made the Si(Li) X-Ray Detector nearly obsolete, the device serves as a useful benchmark and still is used in special instances where its large, sensitive depth is essential. Semiconductor X-Ray Detectors focuses on the history and development of Si(Li) X-Ray Detect...

  17. 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

  18. 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.

  19. 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

  20. 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...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-06-15

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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. Avalanche Photodiodes as Fast X-ray Detectors.

    Science.gov (United States)

    Kishimoto, S

    1998-05-01

    An avalanche photodiode (APD) detector provides a sub-nanosecond time resolution and an output rate of more than 10(8) counts s(-1) of synchrotron X-rays. Moreover, the APD has the advantage of low noise. A review of recent developments of detectors using APD devices designed for X-ray experiments is presented in this paper. One of the detectors has an excellent time response of 100 ps resolution and a narrow width on its response function, 1.4 ns at 10(-5) maximum. The other consists of a stack of four diodes and has a transmission structure. The stacked detector improved the efficiency for X-rays, e.g. 55% at 16.53 keV. The output rates reached more than 10(8) counts s(-1) per device.

  12. 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.

  13. X-ray sensitivity measurements on CVD diamond film detectors

    Energy Technology Data Exchange (ETDEWEB)

    Foulon, F.; Pochet, T. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Electronique et d`Instrumentation Nucleaire; Gheeraert, E. [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France)

    1993-12-31

    Microwave chemical vapor deposited (CVD) diamond films have been used to fabricate radiation detectors. The polycrystalline diamond films have a resistivity of 10{sup 12} ohm.cm and carrier mobility and lifetime of about 280 cm{sup 2}/V.s and 530 ps. The detector response to laser pulses (355, 532 and 1064 nm), X-ray flux (15-50 keV) and alpha particles ({sup 241}Am, 5.49 MeV) has been investigated. The response speed of the detector is in the 100 ps range. A sensitivity of about 3 x 10{sup -10} A/V.Gy.s was measured under 50 keV X-ray flux. The detector current response to X-ray flux is almost linear. It is also shown that CVD diamond detectors can be used for alpha particle counting. (authors). 9 figs., 25 refs.

  14. X-Ray Detector Simulations - Oral Presentation

    Energy Technology Data Exchange (ETDEWEB)

    Tina, Adrienne [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-20

    The free-electron laser at LCLS produces X-Rays that are used in several facilities. This light source is so bright and quick that we are capable of producing movies of objects like proteins. But making these movies would not be possible without a device that can detect the X-Rays and produce images. We need X-Ray cameras. The challenges LCLS faces include the X-Rays’ high repetition rate of 120 Hz, short pulses that can reach 200 femto-seconds, and extreme peak brightness. We need detectors that are compatible with this light source, but before they can be used in the facilities, they must first be characterized. My project was to do just that, by making a computer simulation program. My presentation discusses the individual detectors I simulated, the details of my program, and how my project will help determine which detector is most useful for a specific experiment.

  15. 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

  16. Neutron and X-ray Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Carini, Gabriella [SLAC National Accelerator Lab., Menlo Park, CA (United States); Denes, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gruener, Sol [Cornell Univ., Ithaca, NY (United States); Lessner, Elianne [Dept. of Energy (DOE), Washington DC (United States). Office of Science Office of Basic Energy Sciences

    2012-08-01

    The Basic Energy Sciences (BES) X-ray and neutron user facilities attract more than 12,000 researchers each year to perform cutting-edge science at these state-of-the-art sources. While impressive breakthroughs in X-ray and neutron sources give us the powerful illumination needed to peer into the nano- to mesoscale world, a stumbling block continues to be the distinct lag in detector development, which is slowing progress toward data collection and analysis. Urgently needed detector improvements would reveal chemical composition and bonding in 3-D and in real time, allow researchers to watch “movies” of essential life processes as they happen, and make much more efficient use of every X-ray and neutron produced by the source The immense scientific potential that will come from better detectors has triggered worldwide activity in this area. Europe in particular has made impressive strides, outpacing the United States on several fronts. Maintaining a vital U.S. leadership in this key research endeavor will require targeted investments in detector R&D and infrastructure. To clarify the gap between detector development and source advances, and to identify opportunities to maximize the scientific impact of BES user facilities, a workshop on Neutron and X-ray Detectors was held August 1-3, 2012, in Gaithersburg, Maryland. Participants from universities, national laboratories, and commercial organizations from the United States and around the globe participated in plenary sessions, breakout groups, and joint open-discussion summary sessions. Sources have become immensely more powerful and are now brighter (more particles focused onto the sample per second) and more precise (higher spatial, spectral, and temporal resolution). To fully utilize these source advances, detectors must become faster, more efficient, and more discriminating. In supporting the mission of today’s cutting-edge neutron and X-ray sources, the workshop identified six detector research challenges

  17. Neutron and X-ray Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Carini, Gabriella [SLAC National Accelerator Lab., Menlo Park, CA (United States); Denes, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gruener, Sol [Cornell Univ., Ithaca, NY (United States); Lessner, Elianne [Dept. of Energy (DOE), Washington DC (United States). Office of Science Office of Basic Energy Sciences

    2012-08-01

    The Basic Energy Sciences (BES) X-ray and neutron user facilities attract more than 12,000 researchers each year to perform cutting-edge science at these state-of-the-art sources. While impressive breakthroughs in X-ray and neutron sources give us the powerful illumination needed to peer into the nano- to mesoscale world, a stumbling block continues to be the distinct lag in detector development, which is slowing progress toward data collection and analysis. Urgently needed detector improvements would reveal chemical composition and bonding in 3-D and in real time, allow researchers to watch “movies” of essential life processes as they happen, and make much more efficient use of every X-ray and neutron produced by the source The immense scientific potential that will come from better detectors has triggered worldwide activity in this area. Europe in particular has made impressive strides, outpacing the United States on several fronts. Maintaining a vital U.S. leadership in this key research endeavor will require targeted investments in detector R&D and infrastructure. To clarify the gap between detector development and source advances, and to identify opportunities to maximize the scientific impact of BES user facilities, a workshop on Neutron and X-ray Detectors was held August 1-3, 2012, in Gaithersburg, Maryland. Participants from universities, national laboratories, and commercial organizations from the United States and around the globe participated in plenary sessions, breakout groups, and joint open-discussion summary sessions. Sources have become immensely more powerful and are now brighter (more particles focused onto the sample per second) and more precise (higher spatial, spectral, and temporal resolution). To fully utilize these source advances, detectors must become faster, more efficient, and more discriminating. In supporting the mission of today’s cutting-edge neutron and X-ray sources, the workshop identified six detector research challenges

  18. 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.

  19. Zero-dark-counting X-ray photon detection using a YAP(Ce)-MPPC detector and its application to computed tomography using gadolinium contrast media

    Science.gov (United States)

    Kami, Syouta; Sato, Eiichi; Kogita, Hayato; Numahata, Wataru; Hamaya, Tatsuki; Nihei, Shinichi; Arakawa, Yumeka; Oda, Yasuyuki; Kodama, Hajime; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sato, Shigehiro; Ogawa, Akira

    2014-07-01

    To measure X-ray spectra and to perform photon-counting computed tomography (PC-CT) with high count rates, we developed a zero-dark-counting spectrometer using a short-decay-time scintillator. A method exploiting a YAP(Ce) [cerium-doped yttrium aluminum perovskite] single crystal scintillator with a decay time of 30 ns and an MPPC (multipixel photon counter) has been developed to count X-ray photons. The photocurrent from the MPPC was amplified by a high-speed current-voltage amplifier, and the event pulse was sent to a multichannel analyzer (MCA) to measure X-ray spectra. The MPPC was driven under pre-Geiger mode at a bias voltage of the MPPC of 70.7 V and a temperature of 23 °C. The PC-CT was accomplished by repeated linear scans and rotations of an object, and projection curves of the object were obtained by the linear scan at a tube current of 1.0 mA. The exposure time for obtaining a tomogram was 10 min at a scan step of 0.5 mm and a rotation step of 1.0°. At a tube voltage of 100 kV, the maximum count rate was 200 kcps. In the PC-CT using gadolinium media, we observed image-contrast variations with changes in lower-level discrimination voltage of the event pulse using a comparator.

  20. 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

  1. The pin pixel detector--X-ray imaging

    CERN Document Server

    Bateman, J E; Derbyshire, G E; Duxbury, D M; Marsh, A S; Simmons, J E; Stephenson, R

    2002-01-01

    The development and testing of a soft X-ray gas pixel detector, which uses connector pins for the anodes is reported. Based on a commercial 100 pin connector block, a prototype detector of aperture 25.4 mm centre dot 25.4 mm can be economically fabricated. The individual pin anodes all show the expected characteristics of small gas detectors capable of counting rates reaching 1 MHz per pin. A 2-dimensional resistive divide readout system has been developed to permit the imaging properties of the detector to be explored in advance of true pixel readout electronics.

  2. 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

  3. 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

  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. Burst Detector X-Ray IIR

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-02-01

    The Burst Detector X-Ray (BDX) instrument for the Block IIR series of Global Positioning System satellites is described. The BDX instrument can locate and characterize exoatmospheric nuclear detonations by using four sensors consisting of sets of filters over silicon diodes to detect x rays of various energies from the burst. On the BDX-IIR, a fifth sensor with a response spanning those of the other sensors confirms coincidences among the four main channels. The mechanical and electronic features of the BDX-IIR and its sensors are described. The calibrations and the system tests used in flight are presented. The commands for the BDX-IIR are given. The messages sent from the BDX-IIR are described in detail.

  6. A Monte Carlo study of x-ray fluorescence in x-ray detectors.

    Science.gov (United States)

    Boone, J M; Seibert, J A; Sabol, J M; Tecotzky, M

    1999-06-01

    Advances in digital x-ray detector systems have led to a renewed interest in the performance of x-ray phosphors and other detector materials. Indirect flat panel x-ray detector and charged coupled device (CCD) systems require a more technologically challenging geometry, whereby the x-ray beam is incident on the front side of the scintillator, and the light produced must diffuse to the back surface of the screen to reach the photoreceptor. Direct detector systems based on selenium have also enjoyed a growing interest, both commercially and academically. Monte Carlo simulation techniques were used to study the x-ray scattering (Rayleigh and Compton) and the more prevalent x-ray fluorescence properties of seven different x-ray detector materials, Gd2O2S, CsI, Se, BaFBr, YTaO4, CaWO4, and ThO2. The redistribution of x-ray energy, back towards the x-ray source, in a forward direction through the detector, and lateral reabsorption in the detector was computed under monoenergetic conditions (1 keV to 130 keV by 1 keV intervals) with five detector thicknesses, 30, 60, 90, 120, and 150 mg/cm2 (Se was studied from 30 to 1000 mg/cm2). The radial distribution (related to the point spread function) of reabsorbed x-ray energy was also determined. Representative results are as follows: At 55 keV, more (31.3%) of the incident x-ray energy escaped from a 90 mg/cm2Gd2O2S detector than was absorbed (27.9%). Approximately 1% of the total absorbed energy was reabsorbed greater than 0.5 mm from the primary interaction, for 90 mg/cm2 CsI exposed at 100 kVp. The ratio of reabsorbed secondary (fluorescence + scatter) radiation to the primary radiation absorbed in the detectors (90 mg/cm2) (S/P) was determined as 10%, 16%, 2%, 12%, 3%, 3%, and 0.3% for a 100 kVp tungsten anode x-ray spectrum, for the Gd2O2S, CsI, Se, BaFBr, YTaO4, CaWO4, and ThO2 detectors, respectively. The results indicate significant x-ray fluorescent escape and reabsorption in common x-ray detectors. These findings

  7. HIgh Rate X-ray Fluorescence Detector

    Energy Technology Data Exchange (ETDEWEB)

    Grudberg, Peter Matthew [XIA LLC

    2013-04-30

    The purpose of this project was to develop a compact, modular multi-channel x-ray detector with integrated electronics. This detector, based upon emerging silicon drift detector (SDD) technology, will be capable of high data rate operation superior to the current state of the art offered by high purity germanium (HPGe) detectors, without the need for liquid nitrogen. In addition, by integrating the processing electronics inside the detector housing, the detector performance will be much less affected by the typically noisy electrical environment of a synchrotron hutch, and will also be much more compact than current systems, which can include a detector involving a large LN2 dewar and multiple racks of electronics. The combined detector/processor system is designed to match or exceed the performance and features of currently available detector systems, at a lower cost and with more ease of use due to the small size of the detector. In addition, the detector system is designed to be modular, so a small system might just have one detector module, while a larger system can have many you can start with one detector module, and add more as needs grow and budget allows. The modular nature also serves to simplify repair. In large part, we were successful in achieving our goals. We did develop a very high performance, large area multi-channel SDD detector, packaged with all associated electronics, which is easy to use and requires minimal external support (a simple power supply module and a closed-loop water cooling system). However, we did fall short of some of our stated goals. We had intended to base the detector on modular, large-area detectors from Ketek GmbH in Munich, Germany; however, these were not available in a suitable time frame for this project, so we worked instead with pnDetector GmbH (also located in Munich). They were able to provide a front-end detector module with six 100 m^2 SDD detectors (two monolithic arrays of three elements each) along with

  8. 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

  9. CMOS APS detector characterization for quantitative X-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Endrizzi, Marco, E-mail: m.endrizzi@ucl.ac.uk [Dipartimento di Fisica, Università di Siena, Via Roma 56, 53100 Siena (Italy); Istituto Nazionale di Fisica Nucleare INFN, sezione di Pisa, 56127 Pisa (Italy); Oliva, Piernicola [Dipartimento di Chimica e Farmacia, Università di Sassari, via Piandanna 4, 07100 Sassari (Italy); Istituto Nazionale di Fisica Nucleare INFN, Sezione di Cagliari, 09042 Cagliari (Italy); Golosio, Bruno [Sezione di Matematica, Fisica e Ingegneria dell' Informazione, Università di Sassari, via Piandanna 4, 07100 Sassari (Italy); Istituto Nazionale di Fisica Nucleare INFN, Sezione di Cagliari, 09042 Cagliari (Italy); Delogu, Pasquale [Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Istituto Nazionale di Fisica Nucleare INFN, sezione di Pisa, 56127 Pisa (Italy)

    2013-03-01

    An X-ray Imaging detector based on CMOS Active Pixel Sensor and structured scintillator is characterized for quantitative X-ray imaging in the energy range 11–30 keV. Linearity, dark noise, spatial resolution and flat-field correction are the characteristics of the detector subject of investigation. The detector response, in terms of mean Analog-to-Digital Unit and noise, is modeled as a function of the energy and intensity of the X-rays. The model is directly tested using monochromatic X-ray beams and it is also indirectly validated by means of polychromatic X-ray-tube spectra. Such a characterization is suitable for quantitative X-ray imaging and the model can be used in simulation studies that take into account the actual performance of the detector.

  10. 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.

  11. A gas microstrip wide angle X-ray detector for application in synchrotron radiation experiments

    CERN Document Server

    Bateman, J E; Derbyshire, G E; Duxbury, D M; Lipp, J; Mir, J A; Simmons, J E; Spill, E J; Stephenson, R; Dobson, B R; Farrow, R C; Helsby, W I; Mutikainen, R; Suni, I

    2002-01-01

    The Gas Microstrip Detector has counting rate capabilities several orders of magnitude higher than conventional wire proportional counters while providing the same (or better) energy resolution for X-rays. In addition the geometric flexibility provided by the lithographic process combined with the self-supporting properties of the substrate offers many exciting possibilities for X-ray detectors, particularly for the demanding experiments carried out on Synchrotron Radiation Sources. Using experience obtained in designing detectors for Particle Physics we have developed a detector for Wide Angle X-ray Scattering studies. The detector has a fan geometry which makes possible a gas detector with high detection efficiency, sub-millimetre spatial resolution and good energy resolution over a wide range of X-ray energy. The detector is described together with results of experiments carried out at the Daresbury Laboratory Synchrotron Radiation Source.

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

    Energy Technology Data Exchange (ETDEWEB)

    Durst, Juergen

    2008-07-22

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

  13. New Detector Development for X-ray Astronomy Project

    Data.gov (United States)

    National Aeronautics and Space Administration — "We propose to continue our detector development program in X-ray astronomy. Under our current grant we are developing a new type of active pixel detector. The...

  14. DUVEX: An X-ray counting system based on YAG:Ce scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Andre, J.-M., E-mail: jean-michel.andre1@upmc.fr [Laboratoire de Chimie Physique - Matiere et Rayonnement, UPMC, CNRS UMR 7614, 11 rue Pierre et Marie Curie, F-75231 Paris Cedex 05 (France); Le Guen, K.; Jonnard, P. [Laboratoire de Chimie Physique - Matiere et Rayonnement, UPMC, CNRS UMR 7614, 11 rue Pierre et Marie Curie, F-75231 Paris Cedex 05 (France); Menesguen, Y. [CEA, LIST, Laboratoire National Henri Becquerel, F-91191 Gif-sur-Yvette (France)

    2011-12-11

    A detector system, called DUVEX, has been developed for the soft-x-ray and extreme ultraviolet domain. It consists of a YAG:Ce scintillator coupled to a photomultiplier module working under vacuum in counting mode. The design and the performances of this detector in terms of yield, absolute efficiency, response and noise are reported. Spectra in the soft x-ray range of different elements (W, Ag, Al, Mg, Cu, N, C and B) obtained in WDS mode using this detector are presented. DUVEX appears as a competitive detection tool in terms of cost and easiness of implementation.

  15. Application of SOI Area Detectors to Synchrotron Radiation X-ray Experiments

    CERN Document Server

    Hashimoto, Ryo; Kumai, Reiji; Kishimoto, Shunji

    2015-01-01

    Application of new detectors using Silicon-On-Insulator (SOI) technology has been started in the Photon Factory, KEK. This project has two purposes. The first purpose is to develop a pulse-counting-type X-ray detector which can be used in synchrotron soft X-ray experiments. The second one is to apply the SOI area detector developed by RIKEN, SOPHIAS, to X-ray diffraction and small-angle scattering experiments in Photon Factory. In this paper, we introduce the current status of our project.

  16. X-ray imaging with the PILATUS 100k detector

    DEFF Research Database (Denmark)

    Bech, Martin; Bunk, O.; David, C.;

    2008-01-01

    We report on the application of the PILATUS 100K pixel detector for medical imaging. Experimental results are presented in the form of X-ray radiographs using standard X-ray absorption contrast and a recently developed phase contrast imaging method. The results obtained with the PILATUS detector...... are compared to results obtained with a conventional X-ray imaging system consisting of an X-ray scintillation screen, lens optics, and a charge coupled device. Finally, the results for both systems are discussed more quantitatively based on an image power spectrum analysis. Udgivelsesdato: April...

  17. Pulse pile-up in hard X-ray detector systems. [for solar X-rays

    Science.gov (United States)

    Datlowe, D. W.

    1975-01-01

    When pulse-height spectra are measured by a nuclear detection system at high counting rates, the probability that two or more pulses will arrive within the resolving time of the system is significant. This phenomenon, pulse pile-up, distorts the pulse-height spectrum and must be considered in the interpretation of spectra taken at high counting rates. A computational technique for the simulation of pile-up is developed. The model is examined in the three regimes where (1) the time between pulses is long compared to the detector-system resolving time, (2) the time between pulses is comparable to the resolving time, and (3) many pulses occur within the resolving time. The technique is used to model the solar hard X-ray experiment on the OSO-7 satellite; comparison of the model with data taken during three large flares shows excellent agreement. The paper also describes rule-of-thumb tests for pile-up and identifies the important detector design factors for minimizing pile-up, i.e., thick entrance windows and short resolving times in the system electronics.

  18. The color of X-rays: Spectral X-ray computed tomography using energy sensitive pixel detectors

    NARCIS (Netherlands)

    Schioppa, E.J.

    2014-01-01

    Energy sensitive X-ray imaging detectors are produced by connecting a semiconductor sensor to a spectroscopic pixel readout chip. In this thesis, the applicability of such detectors to X-ray Computed Tomography (CT) is studied. A prototype Medipix based silicon detector is calibrated using X-ray flu

  19. Kinetic Inductance Detectors for X-Ray Spectroscopy

    Science.gov (United States)

    Cecil, T.; Miceli, A.; Gades, L.; Datesman, A.; Quaranta, O.; Yefremenko, V.; Novosad, V.; Mazin, B.

    The lack of efficient x-ray detectors is often the main factor limiting the effective use of ever more powerful synchrotron light sources. Spectroscopic X-ray detectors are used for a wide variety of synchrotron experiments including X-ray micro/nano-probes and X-ray absorption spectroscopy for biology and geophysical applications. The current state-of-art spectroscopic X-ray detectors are semiconductor devices, and their energy resolutions are approaching their theoretical limit of about 100 eV at 6 keV. We describe a detector research and development program to develop the next-generation of high-resolution spectroscopic X-ray detectors using superconducting Kinetic Inductance Detectors (KIDs). With a required energy per charge carrier four orders of magnitude smaller than that of Si, superconducting detectors offer up to two orders of magnitude increase in energy resolution. In addition, KIDs can be optimized for detection of photons ranging in energy from hard X-ray to IR.

  20. 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.

  1. 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.

  2. Filtered fluorescer x-ray detector

    Energy Technology Data Exchange (ETDEWEB)

    Bruns, H.C.; Emig, J.A.; Thoe, R.S.; Springer, P.T.; Hernandez, J.A.

    1995-04-01

    Recently, an instrument capable of measuring x-rays between 8 and 90 keV was conceived to help understand conditions pertaining to pulsed power research. This resulted in the development of a versatile device that would incrementally detect x-rays emitted at predetermined energy bands over this range. To accomplish this, an array of well characterized filter-fluorescer combinations were produced which would allow fluoresced x-rays to be observed by time resolved electro-optical devices. As many as sixteen channels could be utilized with each channel having a corresponding background channel. Upon completion of the device, a three week series of experiments was then successfully carried out.

  3. High-resolution detectors for soft X-ray spectroscopy

    OpenAIRE

    Soman, Matthew

    2014-01-01

    Resonant Inelastic X-ray Scattering (RIXS) is a modern soft X-ray spectroscopy technique used to investigate the structure of and excitations in materials. It requires high resolution spectrometers and a brilliant, tunable, X-ray source and therefore is carried out at spectrometers such as SAXES at the Swiss Light Source Light, a synchrotron at the Paul Scherrer Institut.\\ud \\ud SAXES uses a grating to disperse X-rays scattered from a sample across a position sensitive detector, a Charge-Coup...

  4. 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.

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

    Directory of Open Access Journals (Sweden)

    Pacella D

    2015-01-01

    Full Text Available 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 detectors, together with the most relevant imaging quality parameters, shows differences between, and advantages of these new C-MOS imagers. X-ray energy-resolved imaging is very attractive not only for the increase of contrast but even for the capability of detecting the nature and composition of the material or tissue to be investigated. Since the X-ray absorption coefficients of the different parts or organs of the patient (object are strongly dependent on the X-ray photon energy, this multienergy ("colored" X-ray imaging could increase enormously the probing capabilities. While dual-energy imaging is now a reality in medical practice, multienergy is still in its early stage, but a promising research activity. Based on this new technique of color X-ray imaging, the entire scheme of source–object–detector could be revised in the future, optimizing spectrum and detector to the nature and composition of the target to be investigated. In this view, a transition to a set of monoenergetic X-ray lines, suitably chosen in energy and intensity, could be envisaged, instead of the present continuous spectra. Keywords: X-ray detectors, X-ray medical imaging, C-MOS imagers, dual and multienergy CT

  6. 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

  7. Cascaded-systems analysis of sandwich x-ray detectors

    Science.gov (United States)

    Kim, D. W.; Kim, J.; Yun, S.; Youn, H.; Kim, H. K.

    2016-12-01

    Active sandwich-like multilayer detectors have been developed, and their potential for motion-artifact-free dual-energy x-ray imaging at a single exposure has been demonstrated in the material decomposition context. Since the sandwich detector uses the x-ray beam transmittance through the front layer, direct x-ray interaction within photodiodes in the front layer is unavoidable, and which can increase noise in the front detector images. Similar direct x-ray interaction can also occur in the rear detector layer. To obtain a better contrast performance, an additional filter layer can be placed between the two detector layers. However, this filter layer can increase adversely noise in images obtained from the rear detector layer by reducing the number of x-ray photons reaching it. A theoretical model, which can describe the signal-to-noise performance of the sandwich detector as functions of various design parameters, has been developed by using a linear cascaded-systems theory. From the cascaded-systems analysis, the direct x-ray interaction increases noise at the high spatial frequencies where the number of secondary quanta lessens. The intermediate filter layer enhances the contribution of additive electronic noise in the overall noise performance of the rear detector layer. The detailed cascaded-systems analysis on the x-ray sandwich detectors are reported in comparisons with the measured noise-power spectra and detective quantum efficiencies. The developed model will be useful for a better design and practical use of a sandwich detector for single-shot dual-energy imaging.

  8. X-ray characterization of CMOS imaging detector with high resolution for fluoroscopic imaging application

    Science.gov (United States)

    Cha, Bo Kyung; Kim, Cho Rong; Jeon, Seongchae; Kim, Ryun Kyung; Seo, Chang-Woo; Yang, Keedong; Heo, Duchang; Lee, Tae-Bum; Shin, Min-Seok; Kim, Jong-Boo; Kwon, Oh-Kyung

    2013-12-01

    This paper introduces complementary metal-oxide semiconductor (CMOS) active pixel sensor (APS)-based X-ray imaging detectors with high spatial resolution for medical imaging application. In this study, our proposed X-ray CMOS imaging sensor has been fabricated by using a 0.35 μm 1 Poly 4 Metal CMOS process. The pixel size is 100 μm×100 μm and the pixel array format is 24×96 pixels, which provide a field-of-view (FOV) of 9.6 mm×2.4 mm. The 14.3-bit extend counting analog-to digital converter (ADC) with built-in binning mode was used to reduce the area and simultaneously improve the image resolution. Both thallium-doped CsI (CsI:Tl) and Gd2O2S:Tb scintillator screens were used as converters for incident X-rays to visible light photons. The optical property and X-ray imaging characterization such as X-ray to light response as a function of incident X-ray exposure dose, spatial resolution and X-ray images of objects were measured under different X-ray energy conditions. The measured results suggest that our developed CMOS-based X-ray imaging detector has the potential for fluoroscopic imaging and cone-beam computed tomography (CBCT) imaging applications.

  9. Expectation Maximization for Hard X-ray Count Modulation Profiles

    CERN Document Server

    Benvenuto, Federico; Piana, Michele; Massone, Anna Maria

    2013-01-01

    This paper is concerned with the image reconstruction problem when the measured data are solar hard X-ray modulation profiles obtained from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)} instrument. Our goal is to demonstrate that a statistical iterative method classically applied to the image deconvolution problem is very effective when utilized for the analysis of count modulation profiles in solar hard X-ray imaging based on Rotating Modulation Collimators. The algorithm described in this paper solves the maximum likelihood problem iteratively and encoding a positivity constraint into the iterative optimization scheme. The result is therefore a classical Expectation Maximization method this time applied not to an image deconvolution problem but to image reconstruction from count modulation profiles. The technical reason that makes our implementation particularly effective in this application is the use of a very reliable stopping rule which is able to regularize the solution providing, ...

  10. Performance of detectors for x-ray crystallography

    Science.gov (United States)

    Stanton, Martin J.; Phillips, Walter C.

    1993-12-01

    The performance of a detector can be characterized by its efficiency for measuring individual x-rays or for measuring Bragg peak intensities. The performance for detecting individual x- rays or for measuring Bragg peak intensities. The performance for detecting individual x-rays is well modeled by the DQE. The performance for measuring Bragg peak intensities in the presence of an x-ray background can be modeled by an expanded definition of the DQE which allows inclusion of experimental constraints, the XDCE. These constraints include the observation that by increasing the crystal-to-detector distance and using a larger detector, Bragg peaks can be better resolved and the x-ray background reduced. Calculation of the XDCE for a detector consisting of a fiberoptic taper with a phosphor x-ray convertor deposited on the large end and a CCD bonded to the small end demonstrate the need to make the detector area relatively large, possibly at the expense of a decrease in the DQE.

  11. X-ray and gamma ray astronomy detectors

    Science.gov (United States)

    Decher, Rudolf; Ramsey, Brian D.; Austin, Robert

    1994-01-01

    X-ray and gamma ray astronomy was made possible by the advent of space flight. Discovery and early observations of celestial x-rays and gamma rays, dating back almost 40 years, were first done with high altitude rockets, followed by Earth-orbiting satellites> once it became possible to carry detectors above the Earth's atmosphere, a new view of the universe in the high-energy part of the electromagnetic spectrum evolved. Many of the detector concepts used for x-ray and gamma ray astronomy were derived from radiation measuring instruments used in atomic physics, nuclear physics, and other fields. However, these instruments, when used in x-ray and gamma ray astronomy, have to meet unique and demanding requirements related to their operation in space and the need to detect and measure extremely weak radiation fluxes from celestial x-ray and gamma ray sources. Their design for x-ray and gamma ray astronomy has, therefore, become a rather specialized and rapidly advancing field in which improved sensitivity, higher energy and spatial resolution, wider spectral coverage, and enhanced imaging capabilities are all sought. This text is intended as an introduction to x-ray and gamma ray astronomy instruments. It provides an overview of detector design and technology and is aimed at scientists, engineers, and technical personnel and managers associated with this field. The discussion is limited to basic principles and design concepts and provides examples of applications in past, present, and future space flight missions.

  12. Silicon Drift Detector for Soft x-ray Spectrometer in Fusion Plasmas

    Institute of Scientific and Technical Information of China (English)

    LI Mei; JU Hong-jun

    2008-01-01

    Silicon drift detector(SDD) is used in the soft x-ray pulse height analyzer(PHA) to measure soft x-ray emissions in fusion plasmas. SDD has the virtues of high count rates and high energy resolution, and the good performances at work temperature of about -10 ℃ achieved by single stage peltier element. The performance and first experimental results from SDD system are presented.

  13. 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.

  14. Accurate determination of segmented X-ray detector geometry.

    Science.gov (United States)

    Yefanov, Oleksandr; Mariani, Valerio; Gati, Cornelius; White, Thomas A; Chapman, Henry N; Barty, Anton

    2015-11-02

    Recent advances in X-ray detector technology have resulted in the introduction of segmented detectors composed of many small detector modules tiled together to cover a large detection area. Due to mechanical tolerances and the desire to be able to change the module layout to suit the needs of different experiments, the pixels on each module might not align perfectly on a regular grid. Several detectors are designed to permit detector sub-regions (or modules) to be moved relative to each other for different experiments. Accurate determination of the location of detector elements relative to the beam-sample interaction point is critical for many types of experiment, including X-ray crystallography, coherent diffractive imaging (CDI), small angle X-ray scattering (SAXS) and spectroscopy. For detectors with moveable modules, the relative positions of pixels are no longer fixed, necessitating the development of a simple procedure to calibrate detector geometry after reconfiguration. We describe a simple and robust method for determining the geometry of segmented X-ray detectors using measurements obtained by serial crystallography. By comparing the location of observed Bragg peaks to the spot locations predicted from the crystal indexing procedure, the position, rotation and distance of each module relative to the interaction region can be refined. We show that the refined detector geometry greatly improves the results of experiments.

  15. Accurate determination of segmented X-ray detector geometry

    Science.gov (United States)

    Yefanov, Oleksandr; Mariani, Valerio; Gati, Cornelius; White, Thomas A.; Chapman, Henry N.; Barty, Anton

    2015-01-01

    Recent advances in X-ray detector technology have resulted in the introduction of segmented detectors composed of many small detector modules tiled together to cover a large detection area. Due to mechanical tolerances and the desire to be able to change the module layout to suit the needs of different experiments, the pixels on each module might not align perfectly on a regular grid. Several detectors are designed to permit detector sub-regions (or modules) to be moved relative to each other for different experiments. Accurate determination of the location of detector elements relative to the beam-sample interaction point is critical for many types of experiment, including X-ray crystallography, coherent diffractive imaging (CDI), small angle X-ray scattering (SAXS) and spectroscopy. For detectors with moveable modules, the relative positions of pixels are no longer fixed, necessitating the development of a simple procedure to calibrate detector geometry after reconfiguration. We describe a simple and robust method for determining the geometry of segmented X-ray detectors using measurements obtained by serial crystallography. By comparing the location of observed Bragg peaks to the spot locations predicted from the crystal indexing procedure, the position, rotation and distance of each module relative to the interaction region can be refined. We show that the refined detector geometry greatly improves the results of experiments. PMID:26561117

  16. 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.

  17. Thermal detectors as single photon X-ray spectrometers

    Science.gov (United States)

    Moseley, S. H.; Kelley, R. L.; Mather, J. C.; Mushotzky, R. F.; Szymkowiak, A. E.; Mccammon, D.

    1985-01-01

    In a thermal detector employed for X-ray spectroscopy applications, the energy of an X-ray is converted to heat in a small mass, and the energy of that X-ray inferred from the size of the temperature rise. The present investigation is concerned with the possibility to make an extremely low heat capacity calorimeter which can be employed as a thermal detector. Several types of calorimeters were fabricated and tested at temperatures as low as approximately 0.05 K. The obtained devices make use of thermistors constructed of melt-doped silicon, nuclear transmutation doped (NTD) germanium, and ion-implanted silicon with a variety of materials for the support and electrical leads. The utility of these microcalorimeters as X-ray spectrometers could be verified.

  18. Improved x-ray spectroscopy with room temperature CZT detectors.

    Science.gov (United States)

    Fritz, Shannon G; Shikhaliev, Polad M; Matthews, Kenneth L

    2011-09-07

    Compact, room temperature x-ray spectroscopy detectors are of interest in many areas including diagnostic x-ray imaging, radiation protection and dosimetry. Room temperature cadmium zinc telluride (CZT) semiconductor detectors are promising candidates for these applications. One of the major problems for CZT detectors is low-energy tailing of the energy spectrum due to hole trapping. Spectral post-correction methods to correct the tailing effect do not work well for a number of reasons; thus it is advisable to eliminate the hole trapping effect in CZT using physical methods rather than correcting an already deteriorated energy spectrum. One method is using a CZT detector with an electrode configuration which modifies the electric field in the CZT volume to decrease low-energy tailing. Another method is to irradiate the CZT surface at a tilted angle, which modifies depth of interaction to decrease low-energy tailing. Neither method alone, however, eliminates the tailing effect. In this work, we have investigated the combination of modified electric field and tilted angle irradiation in a single detector to further decrease spectral tailing. A planar CZT detector with 10 × 10 × 3 mm³ size and CZT detector with 5 × 5 × 5 mm³ size and cap-shaped electrode were used in this study. The cap-shaped electrode (referred to as CAPture technology) modifies the electric field distribution in the CZT volume and decreases the spectral tailing effect. The detectors were investigated at 90° (normal) and 30° (tilted angle) irradiation modes. Two isotope sources with 59.6 and 122 keV photon energies were used for gamma-ray spectroscopy experiments. X-ray spectroscopy was performed using collimated beams at 60, 80 and 120 kVp tube voltages, in both normal and tilted angle irradiation. Measured x-ray spectra were corrected for K x-ray escape fractions that were calculated using Monte Carlo methods. The x-ray spectra measured with tilted angle CAPture detector at 60, 80 and 120

  19. Technological aspects of GEM detector design and assembling for soft x-ray application

    Science.gov (United States)

    Kowalska-Strzeciwilk, E.; Chernyshova, M.

    2016-09-01

    Various types of Micro Pattern Gas Detectors (MPGDs) found applications as tracking detectors in high energy particle physics experiments and as well as imaging detectors, especially for soft X-rays. These detectors offer several advantages like high count rate capability, good spatial and energy resolution, low cost and possibility of constructing large area detectors with very small dead area. Construction, like the triple Gas Electron Multiplier (GEM) detector has become a standard detector, which is widely used for different imaging applications. Some examples of such applications are: monitoring the impurity in plasma, imaging system for mapping of some parameters like pigment distributions using X-ray fluorescence technique[1], proton range radiography system for quality assurance in hadron therapy. Measuring of the Soft X-Ray (SXR) radiation of magnetic fusion plasma is a standard way of accessing valuable information, for example, about particle transport and MHD. The paper is focused on the design of GEM based soft Xray radiation detecting system which is under development. It is dedicated to study soft X-ray emission of plasma radiation with focus on tungsten emission lines energy region. The paper presents the designing, construction and assembling of a prototype of two triple-GEM detectors for soft-X ray application on the WEST device.

  20. A gas microstrip X-ray detector for soft energy fluorescence EXAFS

    CERN Document Server

    Smith, A D; Derbyshire, G E; Duxbury, D M; Lipp, J; Spill, E J; Stephenson, R

    2001-01-01

    Gas microstrip detectors have been previously developed by the particle physics community, where their robustness, compactness and high counting speed have been recognised. These features are particularly attractive to synchrotron radiation use. In this paper, we describe a gas microstrip detector employing multi-element readout and specifically developed for high count rate fluorescence EXAFS at soft X-ray energies below 4 keV.

  1. Anisotropic imaging performance in indirect x-ray imaging detectors.

    Science.gov (United States)

    Badano, Aldo; Kyprianou, Iacovos S; Sempau, Josep

    2006-08-01

    We report on the variability in imaging system performance due to oblique x-ray incidence, and the associated transport of quanta (both x rays and optical photons) through the phosphor, in columnar indirect digital detectors. The analysis uses MANTIS, a combined x-ray, electron, and optical Monte Carlo transport code freely available. We describe the main features of the simulation method and provide some validation of the phosphor screen models considered in this work. We report x-ray and electron three-dimensional energy deposition distributions and point-response functions (PRFs), including optical spread in columnar phosphor screens of thickness 100 and 500 microm, for 19, 39, 59, and 79 keV monoenergetic x-ray beams incident at 0 degrees, 10 degrees, and 15 degrees. In addition, we present pulse-height spectra for the same phosphor thickness, x-ray energies, and angles of incidence. Our results suggest that the PRF due to the phosphor blur is highly nonsymmetrical, and that the resolution properties of a columnar screen in a tomographic, or tomosynthetic imaging system varies significantly with the angle of x-ray incidence. Moreover, we find that the noise due to the variability in the number of light photons detected per primary x-ray interaction, summarized in the information or Swank factor, is somewhat independent of thickness and incidence angle of the x-ray beam. Our results also suggest that the anisotropy in the PRF is not less in screens with absorptive backings, while the noise introduced by variations in the gain and optical transport is larger. Predictions from MANTIS, after additional validation, can provide the needed understanding of the extent of such variations, and eventually, lead to the incorporation of the changes in imaging performance with incidence angle into the reconstruction algorithms for volumetric x-ray imaging systems.

  2. Low-energy X-ray detection with an in-vacuum PILATUS detector

    Science.gov (United States)

    Marchal, Julien; Luethi, Benjamin; Ursachi, Catalin; Mykhaylyk, Vitaliy; Wagner, Armin

    2011-11-01

    The feasibility of using PILATUS single-X-ray-photon counting detectors for long-wavelength macromolecular crystallography was investigated by carrying out a series of experiments at Diamond Light Source. A water-cooled PILATUS 100k detector was tested in vacuum with monochromatic 3 keV X-rays on the Diamond test beamline B16. Effects of detector cooling on noise performance, energy calibration and threshold trimming were investigated. When detecting 3 keV X-rays, the electronic noise of the analogue output of pixel preamplifiers forces the threshold to be set at a higher level than the 50% energy level recommended to minimize charge-sharing effects. The influence of threshold settings at low X-ray energy was studied by characterizing the detector response to a collimated beam of 3 keV X-rays scanned across several pixels. The relationship between maximum count rate and minimum energy threshold was investigated separately for various detector gain settings.

  3. X-ray Characterization of a Multichannel Smart-Pixel Array Detector

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Steve; Haji-Sheikh, Michael; Huntington, Andrew; Kline, David; Lee, Adam; Li, Yuelin; Rhee, Jehyuk; Tarpley, Mary; Walko, Donald A.; Westberg, Gregg; Williams, George; Zou, Haifeng; Landahl, Eric

    2016-01-01

    The Voxtel VX-798 is a prototype X-ray pixel array detector (PAD) featuring a silicon sensor photodiode array of 48 x 48 pixels, each 130 mu m x 130 mu m x 520 mu m thick, coupled to a CMOS readout application specific integrated circuit (ASIC). The first synchrotron X-ray characterization of this detector is presented, and its ability to selectively count individual X-rays within two independent arrival time windows, a programmable energy range, and localized to a single pixel is demonstrated. During our first trial run at Argonne National Laboratory's Advance Photon Source, the detector achieved a 60 ns gating time and 700 eV full width at half-maximum energy resolution in agreement with design parameters. Each pixel of the PAD holds two independent digital counters, and the discriminator for X-ray energy features both an upper and lower threshold to window the energy of interest discarding unwanted background. This smart-pixel technology allows energy and time resolution to be set and optimized in software. It is found that the detector linearity follows an isolated dead-time model, implying that megahertz count rates should be possible in each pixel. Measurement of the line and point spread functions showed negligible spatial blurring. When combined with the timing structure of the synchrotron storage ring, it is demonstrated that the area detector can perform both picosecond time-resolved X-ray diffraction and fluorescence spectroscopy measurements.

  4. Artefacts of X-ray area detectors caused by diffraction

    CERN Document Server

    Gollwitzer, Christian

    2013-01-01

    When an X-ray area detector based on a single crystalline material, for instance a state of the art hybrid-pixel detector, is illuminated from a point source by monochromatic radiation, a pattern of lines appears, which overlays the detected image. These lines can easily be found by scattering experiments with smooth patterns such as small angle X-ray scattering. The origin of this effect is Bragg reflection in the absorber of the detector. We present experimental images over a photon energy range from 3.4 keV to 10 keV together with a theoretical analysis. The patterns can be exploited to check the alignment of the detector surface to the direct beam, and of individual detector modules to each other for modular detectors, as well as for energy calibration of the radiation.

  5. [Flat-panel detectors in X-ray systems].

    Science.gov (United States)

    Spahn, M; Heer, V; Freytag, R

    2003-05-01

    For all application segments X-ray systems with flat-panel detectors increasingly enter the market. In digital radiography,mammography and cardiologic angiography flat-panel detectors are already well established while they are made ready for market introduction in general angiography and fluoroscopy. Two flat-panel detector technologies are available. One technology is based on an indirect conversion process of X-rays while the other one uses a direct conversion method. For radiography and dynamic applications the indirect method provides substantial advantages, while the direct method has some benefits for mammography. In radiography and mammography flat-panel detectors lead to clear improvements with respect to workflow, image quality and dose reduction potentials. These improvements are fostered by the immediate availability of the image, the large dynamic range and the high sensitivity to X-rays. New applications and the use of complex image processing algorithms have the potential to enlarge the present diagnostic range of applications. Up to now, image intensifiers are still the well-established technology for angiography and fluoroscopy. Nevertheless flat-panel detectors begin to enter this field, especially in cardiologic angiography. Characteristics of flat-panel detectors such as the availability of distortion-free images, the excellent contrast resolution, the large dynamic range, the high sensitivity to X-rays and the usability in magnetic fields provide the basis for improved and new diagnostic and interventional methods.

  6. 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.

  7. Study of X-ray Imaging of GEM Detector

    Institute of Scientific and Technical Information of China (English)

    LI; Xiao-mei; HU; Shou-yang; JIAN; Si-yu; ZHOU; Jing; LI; Xing-long; LIANG; Hao; ZHOU; Shu-hua

    2015-01-01

    A 10cm×10cm GEM detector made by 3GEM foils was used in the X-ray imaging experiment.2-D strips readout mode was used and each dimension has 256channels with a pitch of 400micrometer.APV25front-end readout chip was introduced in the detector,and the backplane connectors were improved in order to adapt the electronics with GEM detector.Since each

  8. A multiple CCD X-ray detector and its first operation with synchrotron radiation X-ray beam

    CERN Document Server

    Suzuki, M; Kumasaka, T; Sato, K; Toyokawa, H; Aries, I F; Jerram, P A; Ueki, T

    1999-01-01

    A 4x4 array structure of 16 identical CCD X-ray detector modules, called the multiple CCD X-ray detector system (MCCDX), was submitted to its first synchrotron radiation experiment at the protein crystallography station of the RIKEN beamline (BL45XU) at the SPring-8 facility. An X-ray diffraction pattern of cholesterol powder was specifically taken in order to investigate the overall system performance.

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

    Science.gov (United States)

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

    2017-03-01

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

  10. X-Ray and Gamma-Ray Radiation Detector

    DEFF Research Database (Denmark)

    2015-01-01

    Disclosed is a semiconductor radiation detector for detecting X-ray and / or gamma-ray radiation. The detector comprises a converter element for converting incident X-ray and gamma-ray photons into electron-hole pairs, at least one cathode, a plurality of detector electrodes arranged with a pitch...... (P) along a first axis, a plurality of drift electrodes, a readout circuitry being configured to read out signals from the plurality of detector electrodes and a processing unit connected to the readout circuitry and being configured to detect an event in the converter element. The readout circuitry...... is further configured to read out signals from the plurality of drift electrodes, and the processing unit is further configured to estimate a location of the event along the first axis by processing signals obtained from both the detector electrodes and the drift electrodes, the location of the event along...

  11. 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...

  12. 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.

  13. X-ray Peltier cooled detectors for X-ray fluorescence analysis

    Energy Technology Data Exchange (ETDEWEB)

    Loupilov, A. E-mail: bsi@bsi.lv; Sokolov, A.; Gostilo, V

    2001-06-01

    The recent results on development of X-ray Si(Li), Si-planar and CdTe p-i-n detectors cooled by Peltier coolers for fabrication of laboratory and portable XRF analysers for different applications are discussed. Low detection limits of XRF analysers are provided by increasing of detectors sensitive surface; improvement of their spectrometrical characteristics; decreasing of front-end-electronics noise level; Peltier coolers and vacuum chambers cooling modes optimization. Solution of all mentioned tasks allowed to develop Peltier cooled detectors with the following performances: (1.) Si(Li) detectors: S=20 mm{sup 2}, thickness=3.5 mm, 175 eV (5.9 keV), 430 eV (59.6 keV); S=100 mm{sup 2}; thickness=4.5 mm, 270 eV (5.9 keV), 485 eV (59.6 keV). (2.) Si-planar detector: S=10 mm{sup 2}, thickness=0.4 mm, 230 eV (5.9 keV), 460 eV (59.6 keV). (3.) CdTe p-i-n detectors: S=16 mm{sup 2}, thickness=0.5 mm, 350 eV (5.9 keV), 585 eV (59.6 keV). S=16 mm{sup 2}, thickness=1.2 mm, 310 eV (5.9 keV), 600 eV (59.6 keV). Advantages and disadvantages of all types of detectors for X-ray fluorescence analysis are compared. Spectra are presented. Application of different XRF analysers based on developed detectors in medicine, environmental science, industry, cryminalistics and history of art are demonstrated.

  14. A new method for determining the sensitivity of X-ray imaging observations and the X-ray number counts

    CERN Document Server

    Georgakakis, A; Laird, E S; Aird, J; Trichas, M

    2008-01-01

    We present a new method for determining the sensitivity of X-ray imaging observations, which correctly accounts for the observational biases that affect the probability of detecting a source of a given X-ray flux, without the need to perform a large number of time consuming simulations. We use this new technique to estimate the X-ray source counts in different spectral bands (0.5-2, 0.5-10, 2-10 and 5-10keV) by combining deep pencil-beam and shallow wide-area Chandra observations. The sample has a total of 6295 unique sources over an area of $\\rm 11.8deg^2$ and is the largest used to date to determine the X-ray number counts. We determine, for the first time, the break flux in the 5-10 keV band, in the case of a double power-law source count distribution. We also find an upturn in the 0.5-2keV counts at fluxes below about 6e-17erg/s/cm2. We show that this can be explained by the emergence of normal star-forming galaxies which dominate the X-ray population at faint fluxes. The fraction of the diffuse X-ray bac...

  15. CCD sensors in synchrotron X-ray detectors

    Science.gov (United States)

    Strauss, M. G.; Naday, I.; Sherman, I. S.; Kraimer, M. R.; Westbrook, E. M.; Zaluzec, N. J.

    1988-04-01

    The intense photon flux from advanced synchrotron light sources, such as the 7-GeV synchrotron being designed at Argonne, require integrating-type detectors. Charge-coupled devices (CCDs) are well suited as synchrotron X-ray detectors. When irradiated indirectly via a phosphor followed by reducing optics, diffraction patterns of 100 cm 2 can be imaged on a 2 cm 2 CCD. With a conversion efficiency of ˜ 1 CCD electron/X-ray photon, a peak saturation capacity of > 10 6 X-rays can be obtained. A programmable CCD controller operating at a clock frequency of 20 MHz has been developed. The readout rate is 5 × 10 6 pixels/s and the shift rate in the parallel registers is 10 6 lines/s. The test detector was evaluated in two experiments. In protein crystallography diffraction patterns have been obtained from a lysozyme crystal using a conventional rotating anode X-ray generator. Based on these results we expect to obtain at a synchrotron diffraction images at a rate of ˜ 1 frame/s or a complete 3-dimensional data set from a single crystal in ˜ 2 min. In electron energy-loss spectroscopy (EELS), the CCD was used in a parallel detection mode which is similar to the mode array detectors are used in dispersive EXAFS. With a beam current corresponding to 3 × 10 9 electron/s on the detector, a series of 64 spectra were recorded on the CCD in a continuous sequence without interruption due to readout. The frame-to-frame pixel signal fluctuations had σ = 0.4% from which DQE = 0.4 was obtained, where the detector conversion efficiency was 2.6 CCD electrons/X-ray photon. These multiple frame series also showed the time-resolved modulation of the electron microscope optics by stray magnetic fields.

  16. Unfolding X-ray spectra using a flat panel detector.

    Science.gov (United States)

    Gallardo, Sergio; Juste, Belén; Pozuelo, Fausto; Ródenas, José; Querol, Andrea; Verdú, Gumersindo

    2013-01-01

    It is difficult to measure the energy spectrum of X-ray tubes due to the pile up effect produced by the high fluence of photons. Using attenuating materials, appropriate detector devices and the Monte Carlo method, primary X-ray spectrum of these devices can be estimated. In this work, a flat panel detector with a PMMA wedge has been used to obtain a dose curve corresponding to certain working conditions of a radiodiagnostic X-ray tube. The relation between the dose curve recorded by the flat panel and the primary X-ray spectrum is defined by a response function. Normally this function can be approximated by a matrix, which can be obtained by means of the Monte Carlo method. Knowing the measured dose curve and the response matrix, the primary X-ray spectrum can be unfolded. However, there are some problems that strongly affect the applicability of this method: i.e. technical features of the flat panel and inherent characteristics of the involved radiation physics (ill-posed problem). Both aspects are analyzed in this work, concluding that the proposed method can be applied with an acceptable accuracy for spectra without characteristic lines, for instance, tungsten anode in the 50-70 kVp range.

  17. Slow scan sit detector for x-ray diffraction studies using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Milch, J R

    1978-10-18

    A TV-type x-ray detector using a SIT vidicon has been used for biological diffraction studies at the EMBL outstation at DESY, Hamburg, Germany. The detector converts the two-dimensional diffraction pattern to a charge pattern on the vidicon target, which is read out in the slow-scan mode. This detector has high DOE, no count-rate limit, and is simple and inexpensive to construct. Radiation from the storage ring DORIS was used to study the structure of live muscle at various phases of contraction. Typically the count-rate on the detector was 10/sup 6/ x-rays/sec and a total exposure of a few seconds was needed to record the weak diffraction from muscle. This compares with usual exposure times of several hours using a rotating anode generator and film.

  18. Small pixel CZT detector for hard X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Matthew David, E-mail: Matt.Wilson@stfc.ac.uk [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Oxfordshire OX11 0QX (United Kingdom); Cernik, Robert [Henry Moseley X-ray Imaging Facility, School of Materials, University of Manchester (United Kingdom); Chen, Henry [Redlen Technologies, Saanichton, British Columbia (Canada); Hansson, Conny [Henry Moseley X-ray Imaging Facility, School of Materials, University of Manchester (United Kingdom); Iniewski, Kris [Redlen Technologies, Saanichton, British Columbia (Canada); Jones, Lawrence L.; Seller, Paul; Veale, Matthew C. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Oxfordshire OX11 0QX (United Kingdom)

    2011-10-01

    A new small pixel cadmium zinc telluride (CZT) detector has been developed for hard X-ray spectroscopy. The X-ray performance of four detectors is presented and the detectors are analysed in terms of the energy resolution of each pixel. The detectors were made from CZT crystals grown by the travelling heater method (THM) bonded to a 20x20 application specific integrated circuit (ASIC) and data acquisition (DAQ) system. The detectors had an array of 20x20 pixels on a 250 {mu}m pitch, with each pixel gold-stud bonded to an energy resolving circuit in the ASIC. The DAQ system digitised the ASIC output with 14 bit resolution, performing offset corrections and data storage to disc in real time at up to 40,000 frames per second. The detector geometry and ASIC design was optimised for X-ray spectroscopy up to 150 keV and made use of the small pixel effect to preferentially measure the electron signal. A {sup 241}Am source was used to measure the spectroscopic performance and uniformity of the detectors. The average energy resolution (FWHM at 59.54 keV) of each pixel ranged from 1.09{+-}0.46 to 1.50{+-}0.57 keV across the four detectors. The detectors showed good spectral performance and uniform response over almost all pixels in the 20x20 array. A large area 80x80 pixel detector will be built that will utilise the scalable design of the ASIC and the large areas of monolithic spectroscopic grade THM grown CZT that are now available. The large area detector will have the same performance as that demonstrated here.

  19. Small pixel CZT detector for hard X-ray spectroscopy

    Science.gov (United States)

    Wilson, Matthew David; Cernik, Robert; Chen, Henry; Hansson, Conny; Iniewski, Kris; Jones, Lawrence L.; Seller, Paul; Veale, Matthew C.

    2011-10-01

    A new small pixel cadmium zinc telluride (CZT) detector has been developed for hard X-ray spectroscopy. The X-ray performance of four detectors is presented and the detectors are analysed in terms of the energy resolution of each pixel. The detectors were made from CZT crystals grown by the travelling heater method (THM) bonded to a 20×20 application specific integrated circuit (ASIC) and data acquisition (DAQ) system. The detectors had an array of 20×20 pixels on a 250 μm pitch, with each pixel gold-stud bonded to an energy resolving circuit in the ASIC. The DAQ system digitised the ASIC output with 14 bit resolution, performing offset corrections and data storage to disc in real time at up to 40,000 frames per second. The detector geometry and ASIC design was optimised for X-ray spectroscopy up to 150 keV and made use of the small pixel effect to preferentially measure the electron signal. A 241Am source was used to measure the spectroscopic performance and uniformity of the detectors. The average energy resolution (FWHM at 59.54 keV) of each pixel ranged from 1.09±0.46 to 1.50±0.57 keV across the four detectors. The detectors showed good spectral performance and uniform response over almost all pixels in the 20×20 array. A large area 80×80 pixel detector will be built that will utilise the scalable design of the ASIC and the large areas of monolithic spectroscopic grade THM grown CZT that are now available. The large area detector will have the same performance as that demonstrated here.

  20. A carbon nanotube based x-ray detector

    Science.gov (United States)

    Boucher, Richard A.; Bauch, Jürgen; Wünsche, Dietmar; Lackner, Gerhard; Majumder, Anindya

    2016-11-01

    X-ray detectors based on metal-oxide semiconductor field effect transistors couple instantaneous measurement with high accuracy. However, they only have a limited measurement lifetime because they undergo permanent degradation due to x-ray beam exposure. A field effect transistor based on carbon nanotubes (CNTs), however, overcomes this drawback of permanent degradation, because it can be reset into its starting state after being exposed to the x-ray beam. In this work the CNTs were deposited using a dielectrophoresis method on SiO2 coated p-type (boron-doped) Si substrates. For the prepared devices a best gate voltage shift of 244 V Gy-1 and a source-drain current sensitivity of 382 nA Gy-1 were achieved. These values are larger than those reached by the currently used MOSFET based devices.

  1. Low-noise multichannel ASIC for high count rate X-ray diffractometry applications

    Energy Technology Data Exchange (ETDEWEB)

    Szczygiel, R. [AGH University of Science and Technology, Department of Measurement and Instrumentation, al. Mickiewicza 30, Krakow (Poland)], E-mail: robert.szczygiel@agh.edu.pl; Grybos, P.; Maj, P. [AGH University of Science and Technology, Department of Measurement and Instrumentation, al. Mickiewicza 30, Krakow (Poland); Tsukiyama, A.; Matsushita, K.; Taguchi, T. [Rigaku Corporation, 3-9-12 Matsubara-cho, Akishima-shi, Tokyo (Japan)

    2009-08-01

    RG64 is a 64-channel ASIC designed for the silicon strip detector readout and optimized for high count rate X-ray imaging applications. In this paper we report on the test results referring to the RG64 noise level, channel uniformity and the operation with a high rate of input signals. The parameters of the RG64-based diffractometry system are compared with the ones based on the scintillation counter. Diffractometry measurement results with silicon strip detectors of different strip lengths and strip pitch are also presented.

  2. Analytic model of energy-absorption response functions in compound X-ray detector materials.

    Science.gov (United States)

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

    2013-10-01

    The absorbed energy distribution (AED) in X-ray imaging detectors is an important factor that affects both energy resolution and image quality through the Swank factor and detective quantum efficiency. In the diagnostic energy range (20-140 keV), escape of characteristic photons following photoelectric absorption and Compton scatter photons are primary sources of absorbed-energy dispersion in X-ray detectors. In this paper, we describe the development of an analytic model of the AED in compound X-ray detector materials, based on the cascaded-systems approach, that includes the effects of escape and reabsorption of characteristic and Compton-scatter photons. We derive analytic expressions for both semi-infinite slab and pixel geometries and validate our approach by Monte Carlo simulations. The analytic model provides the energy-dependent X-ray response function of arbitrary compound materials without time-consuming Monte Carlo simulations. We believe this model will be useful for correcting spectral distortion artifacts commonly observed in photon-counting applications and optimal design and development of novel X-ray detectors.

  3. A novel compact Tokamak Hard X-ray diagnostic detector

    Institute of Scientific and Technical Information of China (English)

    曹靖; 蒋春雨; 赵艳凤; 杨青巍; 阴泽杰

    2015-01-01

    A compact X-ray detector based on the lutetium yttrium oxyorthosilicate scintillator (LYSO) and silicon photomultiplier (SiPM) has been designed and fabricated for the hard X-ray diagnosis on the HL 2A and HL 2M Tokamak devices. The LYSO scintillator and SiPM in small dimensions were combined in a heat shrink tube package, making the detector compact and integrative. The Monte Carlo particle transport simulation tool, Geant4, was utilized for the design of the detector for the hard X-ray from 10 keV to 200 keV and the best structure scheme was presented. Finally, the detector was used to measure the photon spectrum of a 137Cs gamma source with a pre-amplifier and a multichannel amplitude analyzer. The measured spectrum is consistent with the theoretic spectrum, it has shown that the energy resolution of the detector is less than 14.8%at an energy of 662 keV.

  4. Energy calibration of the pixels of spectral X-ray detectors.

    Science.gov (United States)

    Panta, Raj Kumar; Walsh, Michael F; Bell, Stephen T; Anderson, Nigel G; Butler, Anthony P; Butler, Philip H

    2015-03-01

    The energy information acquired using spectral X-ray detectors allows noninvasive identification and characterization of chemical components of a material. To achieve this, it is important that the energy response of the detector is calibrated. The established techniques for energy calibration are not practical for routine use in pre-clinical or clinical research environment. This is due to the requirements of using monochromatic radiation sources such as synchrotron, radio-isotopes, and prohibitively long time needed to set up the equipment and make measurements. To address these limitations, we have developed an automated technique for calibrating the energy response of the pixels in a spectral X-ray detector that runs with minimal user intervention. This technique uses the X-ray tube voltage (kVp) as a reference energy, which is stepped through an energy range of interest. This technique locates the energy threshold where a pixel transitions from not-counting (off) to counting (on). Similarly, we have developed a technique for calibrating the energy response of individual pixels using X-ray fluorescence generated by metallic targets directly irradiated with polychromatic X-rays, and additionally γ-rays from (241)Am. This technique was used to measure the energy response of individual pixels in CdTe-Medipix3RX by characterizing noise performance, threshold dispersion, gain variation and spectral resolution. The comparison of these two techniques shows the energy difference of 1 keV at 59.5 keV which is less than the spectral resolution of the detector (full-width at half-maximum of 8 keV at 59.5 keV). Both techniques can be used as quality control tools in a pre-clinical multi-energy CT scanner using spectral X-ray detectors.

  5. Development of a stacked detector system for the x-ray range and its possible applications

    Science.gov (United States)

    Maier, Daniel; Limousin, Olivier; Meuris, Aline; Pürckhauer, Sabina; Santangelo, Andrea; Schanz, Thomas; Tenzer, Christoph

    2014-07-01

    We have constructed a stacked detector system operating in the X-ray range from 0.5 keV to 250 keV that consists of a Si-based 64×64 DePFET-Matrix in front of a CdTe hybrid detector called Caliste-64. The setup is operated under laboratory conditions that approximate the expected environment of a space-borne observatory. The DePFET detector is an active pixel matrix that provides high count-rate capabilities with a near Fanolimited spectral resolution at energies up to 15 keV. The Caliste-64 hard X-ray camera consists of a 1mm thick CdTe crystal combined with very compact integrated readout electronics, constituting a high performance spectro-imager with event-triggered time-tagging capability in the energy range between 2 keV and 200 keV. In this combined geometry the DePFET detector works as the Low Energy Detector (LED) while the Caliste-64 - as the High Energy Detector (HED) - detects predominantly the high energetic photons that have passed the LED. In addition to the individual optimization of both detectors, we use the setup to test and optimize the performance of the combined detector system. Side-effects like X-ray fluorescence photons, electrical crosstalk, and mutual heating have negative impacts on the data quality and will be investigated. Besides the primary application as a combined imaging detector system with high sensitivity across a broad energy range, additional applications become feasible. Via the analysis of coincident events in both detectors we can estimate the capabilities of the setup to be used as a Compton camera and as an X-ray polarimeter - both desirable functionalities for use in the lab as well as for future X-ray missions.

  6. Recent developments in X-ray imaging detectors

    CERN Document Server

    Moy, J P

    2000-01-01

    The replacement of the radiographic film in medical imaging has been the driving force in X-ray imaging developments. It requires a approx 40 cm wide detector to cover all examinations, an equivalent noise level of 1-5 X-ray quanta per pixel, and spatial resolution in the range 100-150 mu m. The need for entirely electronic imaging equipments has fostered the development of many X-ray detectors, most of them based on an array of amorphous silicon pixels, which is the only technology capable to achieve such large areas. Essentially, two concepts have been implemented: - intermediate conversion of X-rays to light by a scintillator, detected by an array of light sensitive pixels, comprising a photodiode and a switching device, either a TFT or a diode. - conversion into electron-hole pairs in a photoconductor, collected by an array of electrodes and switches. In both cases, charge amplifiers read the generated charges line by line. Scintillator and photoconductor-based systems are now close to production. They ac...

  7. HEXITEC: A Next Generation Hard X-ray Detector for Solar Observations

    Science.gov (United States)

    Ryan, Daniel; Christe, Steven; Shih, Albert; Inglis, Andrew R.; Gregory, Kyle; Baumgartner, Wayne H.; Gaskin, Jessica; Wilson-Hodge, Colleen; Seller, Paul; Wilson, Matthew; Veale, Matthew C.; Panessa, Marco

    2016-05-01

    There is an increasing demand in solar physics for high resolution X-ray spectroscopic imaging. Such observations would present ground-breaking opportunities to study the poorly understood high energy processes in the solar corona such as solar flares, coronal heating, etc. However, such observations require a new breed of solid-state detectors sensititve to high energy X-rays with fine independent pixels to subsample the point spread function (PSF) of the X-ray optics. They must also be capable of handling very high count rates as photon fluxes from solar flares often cause pileup in current detectors. The Rutherford Appleton Laboratory (RAL) has recently developed a new Cadmium Telluride (CdTe) detector system, dubbed HEXITEC (High Energy X-ray Imaging Technology). It is an 80x80 array of 250 micron independent pixels sensitive in the 4--80 keV band and capable of a high full frame readout rate of 10 kHz. HEXITEC provides the smallest independently read out pixels currently available, and are well matched to the few arcsecond PSF produced by the current and next generation hard X-ray focusing optics. NASA's Goddard and Marshall Space Flight Centers are collaborating with RAL to develop these detectors for use on future space-borne hard X-ray focusing telescopes. In this poster we show the latest results on HEXITEC's imaging capability, high read out rate, and energy sensitivity and reveal it to be ideal for such future instruments. The potential observations obtained by combining HEXITEC with the next generation of X-ray focusing optics could to revolutionize our understanding of high energy processes in the solar corona.

  8. CZT Detector Development for Hard X-ray Astronomy

    Science.gov (United States)

    Garson, Alfred, III; Li, Q.; Beilicke, M.; Bose, R.; Burger, A.; Dowkonnt, P.; Groza, M.; Simburger, G.; Krawczynski, H.

    2008-05-01

    Cadmium Zinc Telluride (CZT) has proven itself as an excellent material for detection of hard X-rays. Advances in crystal growth have increased the quality and size of available single CZT crystals. We report on our ongoing development and characterization of CZT detector systems. With our dedicated class-100 cleanroom, we fabricate detectors using CZT crystals from different manufactures. Using photolithography and e-beam evaporation, we can produce detectors with different contact designs (pixellated, strip, monolithic, steering grid), contact dimensions (down to 50 microns), and contact materials (In, Ti, Au, etc.) . In addition, we develop ASIC readouts for various CZT detector applications, including our characterization of the detectors. We measure I-V and C-V curves for the detectors as well as their spectroscopic performance. We compare measured results with those from detailed modelling and simulations. The CZT detector systems can then be optimized for applications such as X-ray imaging and polarimetry with satellite or balloon-borne instruments.

  9. Superconducting tunnel junction detectors for soft x-ray astrophysics

    Science.gov (United States)

    Verhoeve, P.; Hijmering, R. A.; Martin, D. D. E.; Jerjen, I.; Peacock, A.; Venn, R.

    2006-06-01

    The requirement on energy resolution for detectors in future X-ray satelite missions such as XEUS (X-ray Evolving Universe Spectroscopy mission) is 80%. In addition, the requirements for field of view and angular resolution demand a detector array of typically 150x150 micron sized pixels in a 30x30 pixel format. DROIDs (Distributed Read Out Imaging Devices), consisting of a superconducting absorber strip with superconducting tunnel junctions (STJs) as read-out devices on either end, can fulfill these requirements. The amplitudes of the two signals from the STJs provide information on the absorption position and the energy of the incoming photon in the absorber. In this paper we present the development status of Ta/Al 1-D DROIDs, as well as the the short term development program that should result in a full size XEUS array.

  10. 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.

  11. Large area x-ray detectors for cargo radiography

    Science.gov (United States)

    Bueno, C.; Albagli, D.; Bendahan, J.; Castleberry, D.; Gordon, C.; Hopkins, F.; Ross, W.

    2007-04-01

    Large area x-ray detectors based on phosphors coupled to flat panel amorphous silicon diode technology offer significant advances for cargo radiologic imaging. Flat panel area detectors provide large object coverage offering high throughput inspections to meet the high flow rate of container commerce. These detectors provide excellent spatial resolution when needed, and enhanced SNR through low noise electronics. If the resolution is reduced through pixel binning, further advances in SNR are achievable. Extended exposure imaging and frame averaging enables improved x-ray penetration of ultra-thick objects, or "select-your-own" contrast sensitivity at a rate many times faster than LDAs. The areal coverage of flat panel technology provides inherent volumetric imaging with the appropriate scanning methods. Flat panel area detectors have flexible designs in terms of electronic control, scintillator selection, pixel pitch, and frame rates. Their cost is becoming more competitive as production ramps up for the healthcare, nondestructive testing (NDT), and homeland protection industries. Typically used medical and industrial polycrystalline phosphor materials such as Gd2O2S:Tb (GOS) can be applied to megavolt applications if the phosphor layer is sufficiently thick to enhance x-ray absorption, and if a metal radiator is used to augment the quantum detection efficiency and reduce x-ray scatter. Phosphor layers ranging from 0.2-mm to 1-mm can be "sandwiched" between amorphous silicon flat panel diode arrays and metal radiators. Metal plates consisting of W, Pb or Cu, with thicknesses ranging from 0.25-mm to well over 1-mm can be used by covering the entire area of the phosphor plate. In some combinations of high density metal and phosphor layers, the metal plate provides an intensification of 25% in signal due to electron emission from the plate and subsequent excitation within the phosphor material. This further improves the SNR of the system.

  12. The color of X-rays Spectral X-ray computed tomography using energy sensitive pixel detectors

    CERN Document Server

    Schioppa, Enrico Junior

    Energy sensitive X-ray imaging detectors are produced by connecting a semiconductor sensor to a spectroscopic pixel readout chip. In this thesis, the applicability of such detectors to X-ray Computed Tomography (CT) is studied. A prototype Medipix based silicon detector is calibrated using X-ray fluorescence. The charge transport properties of the sensor are characterized using a high energy beam of charged particles at the Super Proton Synchrotron (SPS) at the European Center for Nuclear Research (CERN). Monochromatic X-rays at the European Synchrotron Radiation Facility (ESRF) are used to determined the energy response function. These data are used to implement a physics-based CT projection operator that accounts for the transmission of the source spectrum through the sample and detector effects. Based on this projection operator, an iterative spectral CT reconstruction algorithm is developed by extending an Ordered Subset Expectation Maximization (OSEM) method. Subsequently, a maximum likelihood based algo...

  13. A new detector system for low energy X-ray fluorescence coupled with soft X-ray microscopy: First tests and characterization

    Science.gov (United States)

    Gianoncelli, Alessandra; Bufon, Jernej; Ahangarianabhari, Mahdi; Altissimo, Matteo; Bellutti, Pierluigi; Bertuccio, Giuseppe; Borghes, Roberto; Carrato, Sergio; Cautero, Giuseppe; Fabiani, Sergio; Giacomini, Gabriele; Giuressi, Dario; Kourousias, George; Menk, Ralf Hendrik; Picciotto, Antonino; Piemonte, Claudio; Rachevski, Alexandre; Rashevskaya, Irina; Stolfa, Andrea; Vacchi, Andrea; Zampa, Gianluigi; Zampa, Nicola; Zorzi, Nicola

    2016-04-01

    The last decades have witnessed substantial efforts in the development of several detector technologies for X-ray fluorescence (XRF) applications. In spite of the increasing trend towards performing, cost-effective and reliable XRF systems, detectors for soft X-ray spectroscopy still remain a challenge, requiring further study, engineering and customization in order to yield effective and efficient systems. In this paper we report on the development, first characterization and tests of a novel multielement detector system based on low leakage current silicon drift detectors (SDD) coupled to ultra low noise custom CMOS preamplifiers for synchrotron-based low energy XRF. This new system exhibits the potential for improving the count rate by at least an order of magnitude resulting in ten-fold shorter dwell time at an energy resolution similar to that of single element silicon drift detectors.

  14. A new detector system for low energy X-ray fluorescence coupled with soft X-ray microscopy: First tests and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Gianoncelli, Alessandra, E-mail: alessandra.gianoncelli@elettra.eu [Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale SS14, km 163.5, Basovizza 34149 (Italy); Bufon, Jernej [INFN Trieste, Padriciano 99, Trieste 34149 (Italy); Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale SS14, km 163.5, Basovizza 34149 (Italy); University of Trieste, Piazzale Europa 1, Trieste 34127 (Italy); Ahangarianabhari, Mahdi [Politecnico di Milano, Via Anzani 42, Como 22100 (Italy); INFN Milano, Via Celoria 16, Milano 20133 (Italy); Altissimo, Matteo [Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale SS14, km 163.5, Basovizza 34149 (Italy); Bellutti, Pierluigi [Fondazione Bruno Kessler, Via Sommarive 18, Trento 38123 (Italy); Bertuccio, Giuseppe [Politecnico di Milano, Via Anzani 42, Como 22100 (Italy); INFN Milano, Via Celoria 16, Milano 20133 (Italy); Borghes, Roberto [Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale SS14, km 163.5, Basovizza 34149 (Italy); Carrato, Sergio [University of Trieste, Piazzale Europa 1, Trieste 34127 (Italy); Cautero, Giuseppe [Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale SS14, km 163.5, Basovizza 34149 (Italy); INFN Trieste, Padriciano 99, Trieste 34149 (Italy); Fabiani, Sergio [INFN Trieste, Padriciano 99, Trieste 34149 (Italy); Giacomini, Gabriele [Fondazione Bruno Kessler, Via Sommarive 18, Trento 38123 (Italy); Giuressi, Dario [Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale SS14, km 163.5, Basovizza 34149 (Italy); INFN Trieste, Padriciano 99, Trieste 34149 (Italy); Kourousias, George [Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale SS14, km 163.5, Basovizza 34149 (Italy); Menk, Ralf Hendrik [Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale SS14, km 163.5, Basovizza 34149 (Italy); INFN Trieste, Padriciano 99, Trieste 34149 (Italy); Picciotto, Antonino; Piemonte, Claudio [Fondazione Bruno Kessler, Via Sommarive 18, Trento 38123 (Italy); Rachevski, Alexandre [INFN Trieste, Padriciano 99, Trieste 34149 (Italy); and others

    2016-04-21

    The last decades have witnessed substantial efforts in the development of several detector technologies for X-ray fluorescence (XRF) applications. In spite of the increasing trend towards performing, cost-effective and reliable XRF systems, detectors for soft X-ray spectroscopy still remain a challenge, requiring further study, engineering and customization in order to yield effective and efficient systems. In this paper we report on the development, first characterization and tests of a novel multielement detector system based on low leakage current silicon drift detectors (SDD) coupled to ultra low noise custom CMOS preamplifiers for synchrotron-based low energy XRF. This new system exhibits the potential for improving the count rate by at least an order of magnitude resulting in ten-fold shorter dwell time at an energy resolution similar to that of single element silicon drift detectors.

  15. Quality control measurements for digital x-ray detectors.

    Science.gov (United States)

    Marshall, N W; Mackenzie, A; Honey, I D

    2011-02-21

    This paper describes a digital radiography (DR) quality control protocol for DR detectors from the forthcoming report from the Institute of Physics and Engineering in Medicine (IPEM). The protocol was applied to a group of six identical caesium iodide (CsI) digital x-ray detectors to assess reproducibility of methods, while four further detectors were assessed to examine the wider applicability. Twelve images with minimal spatial frequency processing are required, from which the detector response, lag, modulation transfer function (MTF), normalized noise power spectrum (NNPS) and threshold contrast-detail (c-d) detectability are calculated. The x-ray spectrum used was 70 kV and 1 mm added copper filtration, with a target detector air kerma of 2.5 µGy for the NNPS and c-d results. In order to compare detector performance with previous imaging technology, c-d data from four screen/film systems were also acquired, at a target optical density of 1.5 and an average detector air kerma of 2.56 µGy. The DR detector images were typically acquired in 20 min, with a further 45 min required for image transfer and analysis. The average spatial frequency for the 50% point of the MTF for six identical detectors was 1.29 mm(-1) ± 0.05 (3.9% coefficient of variation (cov)). The air kerma set for the six systems was 2.57 µGy ± 0.13 (5.0% cov) and the NNPS at this air kerma was 1.42 × 10(-5) mm(2) (6.5% cov). The detective quantum efficiency (DQE) measured for the six identical detectors was 0.60 at 0.5 mm(-1), with a maximum cov of 10% at 2.9 mm(-1), while the average DQE was 0.56 at 0.5 mm(-1) for three CsI detectors from three different manufacturers. Comparable c-d performance was found for these detectors (5.9% cov) with an average threshold contrast of 0.46% for 11 mm circular discs. The average threshold contrast for the S/F systems was 0.70% at 11 mm, indicating superior imaging performance for the digital systems. The protocol was found to be quick, reproducible and

  16. High resolution, multiple-energy linear sweep detector for x-ray imaging

    Science.gov (United States)

    Perez-Mendez, V.; Goodman, C.A.

    1996-08-20

    Apparatus is disclosed for generating plural electrical signals in a single scan in response to incident X-rays received from an object. Each electrical signal represents an image of the object at a different range of energies of the incident X-rays. The apparatus comprises a first X-ray detector, a second X-ray detector stacked upstream of the first X-ray detector, and an X-ray absorber stacked upstream of the first X-ray detector. The X-ray absorber provides an energy-dependent absorption of the incident X-rays before they are incident at the first X-ray detector, but provides no absorption of the incident X-rays before they are incident at the second X-ray detector. The first X-ray detector includes a linear array of first pixels, each of which produces an electrical output in response to the incident X-rays in a first range of energies. The first X-ray detector also includes a circuit that generates a first electrical signal in response to the electrical output of each of the first pixels. The second X-ray detector includes a linear array of second pixels, each of which produces an electrical output in response to the incident X-rays in a second range of energies, broader than the first range of energies. The second X-ray detector also includes a circuit that generates a second electrical signal in response to the electrical output of each of the second pixels. 12 figs.

  17. Polarization in CdTe radiation detectors at high X-ray photon fluxes (Conference Presentation)

    Science.gov (United States)

    Franc, Jan; Dědič, Václav; Pekárek, Jakub; Belas, Eduard; Touš, Jan

    2016-09-01

    In this contribution we show an improvement of a spectroscopic response of CZT X-ray detector operating at high fluxes of X-ray tube by simultaneous infrared light illumination with a wavelength of 1200 nm. CZT detectors usually suffer from a polarization effect while their internal electric field can be strongly deformed due to a trapping of photogenerated holes. We describe a mechanism of an optically induced depolarization peaking at photon energy of about 1 eV ( 1240 nm) due to an optical transition of electrons from the valence band to the deep level. The depolarization effect is accompanied by a decrease of the detector current which results in a lower noise entering the preamplifier of detector readout circuit. We have observed that it is possible to restore originally distorted X-ray spectra using additional 1200 nm LED illumination with a photon flux of 10^16 cm^-2s^-1 at approximately two times higher X-ray flux than without LED. The number of detected counts was in the range of 10^5-10^6mm^2s^-1. The restoration of the spectrum by continuous infrared light is accompanied by decrease of dark current. We explain this effect by light induced changes of profile of the electric filed that leads to decrease of the electron current injected from the cathode.

  18. A silicon strip detector coupled to the RX64 ASIC for X-ray diagnostic imaging

    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, L.M.; Prino, F. E-mail: prino@to.infn.it; Ramello, L.; Sitta, M.; Swientek, K.; Taibi, A.; Tuffanelli, A.; Wheadon, R.; Wiacek, P

    2003-11-21

    First results from a silicon microstrip detector with 100 {mu}m pitch coupled to the RX64 ASIC are presented. The system is capable of single photon counting in digital X-ray imaging, with possible applications to dual energy mammography and angiography. The main features of the detecting system are low noise, good spatial resolution and high counting rate capability. The energy resolution and the conversion efficiency of the system are discussed, based on results obtained with fluorescence X-ray sources and quasi-monochromatic X-ray beams in the 8-36 keV energy range, with strips being either orthogonal or parallel to the incoming X-rays. We present also preliminary imaging results obtained with a plexiglass phantom with tiny cylindrical cavities filled with iodate solution, simulating patient vessels; in this case the X-ray beam has two components, respectively below and above the iodine K-edge at 33.17 keV.

  19. 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.

  20. 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.

  1. Measurements of Si Hybrid CMOS X-Ray Detector Characteristics

    CERN Document Server

    Bongiorno, Stephen D; Burrows, David N; Cook, Robert; Bai, Yibin; Farris, Mark

    2009-01-01

    The development of Hybrid CMOS Detectors (HCDs) for X-Ray telescope focal planes will place them in con- tention with CCDs on future satellite missions due to their faster frame rates, flexible readout scenarios, lower power consumption, and inherent radiation hardness. CCDs have been used with great success on the current generation of X-Ray telescopes (e.g. Chandra, XMM, Suzaku, and Swift). However their bucket-brigade read-out architecture, which transfers charge across the chip with discrete component readout electronics, results in clockrate limited readout speeds that cause pileup (saturation) of bright sources and an inherent susceptibility to radiation induced displacement damage that limits mission lifetime. In contrast, HCDs read pixels with low power, on-chip multiplexer electronics in a random access fashion. Faster frame rates achieved with multi-output readout design will allow the next generation's larger effective area telescopes to observe bright sources free of pileup. Radiation damaged latt...

  2. Matrix-addressed x-ray detector arrays

    Science.gov (United States)

    Street, Robert A.; Apte, Raj B.; Boyce, James B.; Ho, Jackson; Lau, Rachel; Lemmi, Francesco; Lu, Jeng-Ping; Mulato, Marcelo; Ready, Steve E.; Van Schuylenbergh, Koenraad

    2000-11-01

    Amorphous silicon (a-Si:H) technology has created a successful manufacturing business for large area active matrix arrays, of which liquid crystal displays (AMLCD) are the best known, and image sensors are an emerging technology for medical x-ray imaging. The large area, flat plate, format is the key feature of the technology that sets it apart from other digital imaging approaches. The principal requirements for medical imaging are sensitivity and high dynamic range. A-Si:H detectors have already proved to perform at least as well as x-ray film for radiographic applications and comparable to image intensifiers for fluoroscopy. There are several approaches to improving the performance of the image sensors is order to achieve higher sensitivity and higher spatial resolution. This paper describes some of these approaches.

  3. First tests of a Medipix-1 pixel detector for X-ray dynamic defectoscopy

    CERN Document Server

    Vavrik, D; Visschers, J; Pospísil, S; Ponchut, C; Zemankova, J

    2002-01-01

    Recent theoretical damage material models describe the dynamic development of voids and microcracks in materials under plastic deformation. For these models, experimental verification is needed. We propose direct and non-destructive observation of the propagation of material damage by measuring changes in transmission of X-rays penetrating a stressed material, using a photon-counting X-ray imager. The present contribution aims to demonstrate the applicability of silicon and gallium-arsenide devices for X-ray transmission measurements with a specimen of high-ductile aluminium alloy under study. The first experiments to determine the resolution and the sensitivity of the proposed method with the Medipix-1 pixel detector are presented.

  4. (55)Fe X-ray Response of HgCdTe NIR Detector Arrays

    Science.gov (United States)

    Fox, Ori; Rauscher, Bernard J.

    2008-01-01

    Conversion gain is a fundamental parameter in detector characteristics that is used to measure many identifying detector properties, including read noise, dark current, and quantum efficiency (QE). Charge coupling effects, such as inter-pixel capacitance, attenuate photon shot noise and result in an overestimation of of conversion gain when implementing the photon transfer technique. The (55)Fe X-ray technique is a direct and simple method by which to measure the conversion gain by comparing the observed instrumental counts (ADU) to the known charge (e-) liberated by a single X-ray photon. Here we present the calibrated pair production energy for 1.7 micron HgCdTe infrared detectors.

  5. Investigating the effect of characteristic x-rays in cadmium zinc telluride detectors under breast computerized tomography operating conditions.

    Science.gov (United States)

    Glick, Stephen J; Didier, Clay

    2013-10-14

    A number of research groups have been investigating the use of dedicated breast computerized tomography (CT). Preliminary results have been encouraging, suggesting an improved visualization of masses on breast CT as compared to conventional mammography. Nonetheless, there are many challenges to overcome before breast CT can become a routine clinical reality. One potential improvement over current breast CT prototypes would be the use of photon counting detectors with cadmium zinc telluride (CZT) (or CdTe) semiconductor material. These detectors can operate at room temperature and provide high detection efficiency and the capability of multi-energy imaging; however, one factor in particular that limits image quality is the emission of characteristic x-rays. In this study, the degradative effects of characteristic x-rays are examined when using a CZT detector under breast CT operating conditions. Monte Carlo simulation software was used to evaluate the effect of characteristic x-rays and the detector element size on spatial and spectral resolution for a CZT detector used under breast CT operating conditions. In particular, lower kVp spectra and thinner CZT thicknesses were studied than that typically used with CZT based conventional CT detectors. In addition, the effect of characteristic x-rays on the accuracy of material decomposition in spectral CT imaging was explored. It was observed that when imaging with 50-60 kVp spectra, the x-ray transmission through CZT was very low for all detector thicknesses studied (0.5-3.0 mm), thus retaining dose efficiency. As expected, characteristic x-ray escape from the detector element of x-ray interaction increased with decreasing detector element size, approaching a 50% escape fraction for a 100 μm size detector element. The detector point spread function was observed to have only minor degradation with detector element size greater than 200 μm and lower kV settings. Characteristic x-rays produced increasing distortion

  6. Energy-discriminating X-ray computed tomography system utilizing a cadmium telluride detector

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Eiichi, E-mail: eiichisato@hotmail.co [Department of Physics, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba 028-3694 (Japan); Abderyim, Purkhet [Department of Physics, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba 028-3694 (Japan); Enomoto, Toshiyuki; Watanabe, Manabu [The 3rd Department of Surgery, Toho University School of Medicine, 2-17-6 Ohashi, Meguro-ku, Tokyo 153-8515 (Japan); Hitomi, Keitaro [Department of Electronics and Intelligent Systems, Tohoku Institute of Technology, 35-1 Yagiyama Kasumi-cho, Taihaku-ku, Sendai 982-8577 (Japan); Takahasi, Kiyomi; Sato, Shigehiro [Department of Microbiology, School of Medicine, Iwate Medical University, 19-1 Uchimaru, Morioka 020-8505 (Japan); Ogawae, Akira [Department of Neurosurgery, School of Medicine, Iwate Medical University, 19-1 Uchimaru, Morioka 020-8505 (Japan); Onagawa, Jun [Department of Electronics, Faculty of Engineering, Tohoku Gakuin University, 1-13-1 Chuo, Tagajo 985-8537 (Japan)

    2010-07-21

    An energy-discriminating K-edge X-ray computed tomography (CT) system is useful for increasing contrast resolution of a target region utilizing contrast media and for reducing the absorbed dose for patients. The CT system is of the first-generation type with a cadmium telluride (CdTe) detector, and a projection curve is obtained by translation scanning using the CdTe detector in conjunction with an x-stage. An object is rotated by the rotation step angle using a turntable between the translation scans. Thus, CT is carried out by repeating the translation scanning and the rotation of an object. Penetrating X-ray photons from the object are detected by the CdTe detector, and event signals of X-ray photons are produced using charge-sensitive and shaping amplifiers. Both the photon energy and the energy width are selected by use of a multi-channel analyzer, and the number of photons is counted by a counter card. Demonstration of enhanced iodine K-edge X-ray CT was carried out by selecting photons with energies just beyond the iodine K-edge energy of 33.2 keV.

  7. Photoelectric X-ray Polarimetry with Gas Pixel Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bellazzini, Ronaldo; Brez, Alessandro [INFN Pisa Largo B. Pontecorvo 3, I-56127 Pisa (Italy); Costa, Enrico [INAF/IASF Rome Via del Fosso del Cavaliere 100, I-00133 Rome (Italy); Minuti, Massimo [INFN Pisa Largo B. Pontecorvo 3, I-56127 Pisa (Italy); Muleri, Fabio [INAF/IASF Rome Via del Fosso del Cavaliere 100, I-00133 Rome (Italy); Pinchera, Michele [INFN Pisa Largo B. Pontecorvo 3, I-56127 Pisa (Italy); Rubini, Alda; Soffitta, Paolo [INAF/IASF Rome Via del Fosso del Cavaliere 100, I-00133 Rome (Italy); Spandre, Gloria, E-mail: Gloria.Spandre@pi.infn.it [INFN Pisa Largo B. Pontecorvo 3, I-56127 Pisa (Italy)

    2013-08-21

    The Gas Pixel Detector, recently developed and continuously improved by Pisa-INFN in collaboration with IASF-Roma (INAF), can visualize the tracks produced within a low Z gas by photoelectrons of few keV. By reconstructing the impact point and the original direction of the photoelectrons, the GPD can measure the polarization plane of X-Ray photons, while preserving the information on the absorption point, the energy and the time of arrival of individual photons. Applied to X-ray Astrophysics, in the focus of grazing incidence telescopes, it can perform angular and energy resolved polarimetry with a large improvement of sensitivity, when compared with the conventional techniques of Bragg diffraction at 45° and Compton scattering around 90°. This configuration has been the basis of POLARIX and HXMT, two pathfinder missions, and was included in the baseline design of IXO, the very large X-ray telescope under study by NASA, ESA and JAXA. We have recently improved the design of this low energy polarimeter (2–10 keV) by modifying the geometry of the absorption cell to minimize any systematic effect that could leave a residual polarization signal for non-polarized source. We will report on the testing of this new concept.

  8. Feasibility Study of Gas Electron Multiplier Detector as an X-Ray Image Sensor

    CERN Document Server

    Shin, Sukyoung; Lee, Soonhyouk

    2015-01-01

    For its ease manufacturing, flexible geometry, and cheap manufacturing cost, the gas electron multiplier (GEM) detector can be used as an x-ray image sensor. For this purpose, we acquired relative detection efficiencies and suggested a method to increase the detection efficiency in order to study the possibility of GEM detector as an x-ray image sensor. The GEM detector system is composed of GEM foils, the instrument system, the gas system, and the negative power supply. The instrument system consists of the A225 charge sensitive preamp, A206 discriminator, and MCA8000D multichannel analyzer. For the gas system, Argon gas was mixed with CO2 to the ratio of 8:2, and for the negative 2,000 volts, the 3106D power supply was used. The CsI-coated GEM foil was used to increase the detection efficiency. Fe-55 was used as an x-ray source and the relative efficiency was acquired by using the ratio of GEM detector to the CdTe detector. The total count method and the energy spectrum method were used to calculate the rel...

  9. Energy Calibration of the Pixels of Spectral X-ray Detectors

    CERN Document Server

    Panta, Raj Kumar; Bell, Stephen T; Anderson, Nigel G; Butler, Anthony P; Butler, Philip H

    2015-01-01

    The energy information acquired using spectral X-ray detectors allows noninvasive identification and characterization of chemical components of a material. To achieve this, it is important that the energy response of the detector is calibrated. The established techniques for energy calibration are not practical for routine use in pre-clinical or clinical research environment. This is due to the requirements of using monochromatic radiation sources such as synchrotron, radio-isotopes, and prohibitively long time needed to set up the equipment and make measurements. To address these limitations, we have developed an automated technique for calibrating the energy response of the pixels in a spectral X-ray detector that runs with minimal user intervention. This technique uses the X-ray tube voltage (kVp) as a reference energy, which is stepped through an energy range of interest. This technique locates the energy threshold where a pixel transitions from not-counting (off) to counting (on). Similarly, we have deve...

  10. Computational modelling of semiconducting X-ray detectors

    CERN Document Server

    Fowler, R F; Greenough, C S

    2002-01-01

    The design of high-performance semiconductor detectors is dominated by requirements on position and energy resolution and speed of operation. We investigate the contribution that three-dimensional transient device modelling can make to understanding these and the potential for its use in the design cycle. Simulations are performed using the EVEREST software to solve the drift-diffusion equations. Extra functionality has been added to allow the generation of electron-hole pairs by, for example, the absorption of an X-ray. Careful time integration can measure the time of arrival of the charge packet at the collecting well. By time integrating the current arriving in the collecting well the spatial distribution of charge can be determined. A simple analytic theory is developed and compared with simulations of a large pixel detector. Comparisons with simulations of a two pixel device show that the analytic approximation is reasonable if the X-ray is absorbed beyond 100 mu m from the well, but events closer show a...

  11. Hybrid Pixel Detectors for gamma/X-ray imaging

    Science.gov (United States)

    Hatzistratis, D.; Theodoratos, G.; Zografos, V.; Kazas, I.; Loukas, D.; Lambropoulos, C. P.

    2015-09-01

    Hybrid pixel detectors are made by direct converting high-Z semi-insulating single crystalline material coupled to complementary-metal-oxide semiconductor (CMOS) readout electronics. They are attractive because direct conversion exterminates all the problems of spatial localization related to light diffusion, energy resolution, is far superior from the combination of scintillation crystals and photomultipliers and lithography can be used to pattern electrodes with very fine pitch. We are developing 2-D pixel CMOS ASICs, connect them to pixilated CdTe crystals with the flip chip and bump bonding method and characterize the hybrids. We have designed a series of circuits, whose latest member consists of a 50×25 pixel array with 400um pitch and an embedded controller. In every pixel a full spectroscopic channel with time tagging information has been implemented. The detectors are targeting Compton scatter imaging and they can be used for coded aperture imaging too. Hybridization using CMOS can overcome the limit put on pixel circuit complexity by the use of thin film transistors (TFT) in large flat panels. Hybrid active pixel sensors are used in dental imaging and other applications (e.g. industrial CT etc.). Thus X-ray imaging can benefit from the work done on dynamic range enhancement methods developed initially for visible and infrared CMOS pixel sensors. A 2-D CMOS ASIC with 100um pixel pitch to demonstrate the feasibility of such methods in the context of X-ray imaging has been designed.

  12. Simulation of medical irradiation and X-ray detector signals

    Energy Technology Data Exchange (ETDEWEB)

    Kreisler, Bjoern

    2010-02-08

    This thesis aims for an improved understanding of medical irradiation. Two major parts are investigated: the beam shaping components of a medical linear accelerator, i.e. the source of the radiation, and the signal generation inside semiconductor sensors, i.e. the detection of the radiation. The direct measurement of the spatial and spectral particle distribution in the irradiation beam is not possible with state of the art detectors due to the high particle flux. The development of new advanced detectors is the goal of the first part of this thesis. The focus is set on the signal generation inside the sensor volume of a semiconductor detector. Incoming particles interact with the sensor material and generate clouds of electron hole pairs. These pairs get separated by an applied bias voltage. The motion of the charge clouds is simulated with a finite element programme taking into account the drift and diffusion. Mirror charges are induced on the electrodes which move due to the motion of the charge cloud. The motion of the induced mirror charges leads to the signal that is detected. The transient calculation of the signals is based on Ramo's theorem. The efficient adjoint formulation of the induction solution is adjusted to doped materials, as for example the electric bias field and hence the motion of the charge cloud is changing with the doping level. The effect of the doping of the material on the signal shape is shown together with influences of different voltages and pixel geometries. Smaller pixels and higher bias voltages can lead to shorter signals which is preferable for high flux measurements. Possible count rate improvements are limited by electric break through, high dark current across the sensor layer and charge sharing. Another option to shorten the signals is the use of steering grid electrodes which modify the electric and the weighting field. This results in shorter signals and thus in a higher possible rate. The detailed Monte

  13. Imaging at soft X-ray wavelengths with high-gain microchannel plate detector systems

    Science.gov (United States)

    Timothy, J. Gethyn

    1986-01-01

    Multianode microchannel array (MAMA) detector systems with formats of 256 x 1024 pixels and active areas of 6 x 26 mm are now under evaluation at visible, UV and soft X-ray wavelengths. Very-large-format versions of the MAMA detectors with formats of 2048 x 2048 pixels and active areas of 52 x 52 mm are under development for use in the NASA Goddard Space Telescope Imaging Spectrograph (STIS). Open-structure versions of these detectors with Cs I photocathodes can provide a high-resolution imaging capability at EUV and soft X-ray wavelengths and can deliver a maximum count rate from each array in excess of 10 to the 6th counts/s. In addition, these detector systems have the unique capability to determine the arrival time of a detected photon to an accuracy of 100 ns or better. The construction, mode of operation, and performance characteristics of the MAMA detectors are described, and the program for the development of the very-large-format detectors is outlined.

  14. Promising X-ray fluorescence tests for superconducting tunneljunction detector

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Stephan; Robinson, Arthur L.

    2001-05-15

    Scientists in the Physical Biosciences Division of the Ernest Orlando Berkeley National Laboratory (Berkeley Lab) studying transition metals in proteins with fluorescence-detected L-edge absorption spectroscopy have found the measurements to be extremely challenging. The difficulty is that the metal centers are present in very dilute concentrations so that their weak fluorescence is often obscured by strong background signals carbon and oxygen. To solve this problem, the Berkeley group has been working with researchers from the Advanced Detector Group at the Lawrence Livermore National Laboratory on an energy-dispersive superconducting tunnel junction x-ray detector. These devices in principle have the energy resolution needed to reveal the metal signal. The most recent results with the latest version of the detector on Beamline 4.0.1-2 at the Advanced Light Source (ALS) illustrate the promise of the cryogenic detector strategy not only for this application but also for spectroscopy of other types of dilute samples. Transition-metal complexes are key elements in many biologically important processes that are catalyzed by proteins (enzymes), photosynthesis being a prime example. The changes in that occur in electronic structure throughout a catalytic cycle are the subject of much research aimed at understanding the mechanisms of these processes. L-edge x-ray spectroscopy offers several advantages relative to the more common K-edge techniques, since it involves allowed transitions to the d-orbitals associated with metal-ligand bonding. It also has a rich multiplet structure interpretable by theory and higher spectral resolution.

  15. Geometry calibration between X-ray source and detector for tomosynthesis with a portable X-ray system.

    Science.gov (United States)

    Sato, Kohei; Ohnishi, Takashi; Sekine, Masashi; Haneishi, Hideaki

    2017-05-01

    Tomosynthesis is attracting attention as a low-dose tomography technology compared with X-ray CT. However, conventional tomosynthesis imaging devices are large and stationary. Furthermore, there is a limitation in the working range of the X-ray source during image acquisition. We have previously proposed the use of a portable X-ray device for tomosynthesis that can be used for ward rounds and emergency medicine. The weight of this device can be reduced by using a flat panel detector (FPD), and flexibility is realized by the free placement of the X-ray source and FPD. Tomosynthesis using a portable X-ray device requires calibration of the geometry between the X-ray source and detector at each image acquisition. We propose a method for geometry calibration and demonstrate tomosynthesis image reconstruction by this method. An image processing-based calibration method using an asymmetric and multilayered calibration object (AMCO) is presented. Since the AMCO is always attached to the X-ray source housing for geometry calibration, the additional setting of a calibration object or marker around or on the patients is not required. The AMCO's multilayer structure improves the calibration accuracy, especially in the out-of-plane direction. Two experiments were conducted. The first was performed to evaluate the calibration accuracy using an XY positioning stage and a gonio stage. As a result, an accuracy of approximately 1 mm was achieved both in the in-plane and out-of-plane directions. An angular accuracy of approximately [Formula: see text] was confirmed. The second experiment was conducted to evaluate the reconstructed image using a foot model phantom. Only the sagittal plane could be clearly observed with the proposed method. We proposed a tomosynthesis imaging system using a portable X-ray device. From the experimental results, the proposed method could provide sufficient calibration accuracy and a clear sagittal plane of the reconstructed tomosynthesis image.

  16. Fast signal processing of a yttrium-aluminum-perovskite:Ce detector for synchrotron x-ray experiments

    Science.gov (United States)

    Harada, Masaaki; Sakurai, Kenji; Saitoh, Kazuhiro; Kishimoto, Shunji

    2001-11-01

    An amplifier has been developed to form narrow pulses of less than 100 ns for a YAP:Ce scintillator, which appears promising as a detector for high-counting rate x-ray measurements. The performance of the detector system has been evaluated with monochromatic 8, 16.5, and 25 keV synchrotron x-ray photons at the Photon Factory. The whole deadtime obtained was 84 ns, which is around 3.5 times the decay time of the scintillation (25 ns), indicating that the present system is almost optimum. It has been found that the counting loss for 1 M counts/s is only 8%-9%, and that the detector can count extremely strong photons up to 5 M counts/s.

  17. X-ray detectors at the Linac Coherent Light Source.

    Science.gov (United States)

    Blaj, Gabriel; Caragiulo, Pietro; Carini, Gabriella; Carron, Sebastian; Dragone, Angelo; Freytag, Dietrich; Haller, Gunther; Hart, Philip; Hasi, Jasmine; Herbst, Ryan; Herrmann, Sven; Kenney, Chris; Markovic, Bojan; Nishimura, Kurtis; Osier, Shawn; Pines, Jack; Reese, Benjamin; Segal, Julie; Tomada, Astrid; Weaver, Matt

    2015-05-01

    Free-electron lasers (FELs) present new challenges for camera development compared with conventional light sources. At SLAC a variety of technologies are being used to match the demands of the Linac Coherent Light Source (LCLS) and to support a wide range of scientific applications. In this paper an overview of X-ray detector design requirements at FELs is presented and the various cameras in use at SLAC are described for the benefit of users planning experiments or analysts looking at data. Features and operation of the CSPAD camera, which is currently deployed at LCLS, are discussed, and the ePix family, a new generation of cameras under development at SLAC, is introduced.

  18. The Al sub x Ga sub 1 sub - sub x As X-ray imaging detector

    CERN Document Server

    Pozela, K; Dileenas, A; Jasutis, V; Dapkus, L; Jucienee, V

    2001-01-01

    An X-ray imaging detector based on the graded-gap Al sub x Ga sub 1 sub - sub x As structures with the CCD camera as an image read-out tool is investigated. High X-ray - light conversion efficiency and X-ray image spatial resolution better than 20 line/mm are obtained.

  19. Highly multiplexible thermal kinetic inductance detectors for x-ray imaging spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ulbricht, Gerhard, E-mail: ulbricht@physics.ucsb.edu; Mazin, Benjamin A.; Szypryt, Paul; Walter, Alex B.; Bockstiegel, Clint [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Bumble, Bruce [NASA Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91125 (United States)

    2015-06-22

    For X-ray imaging spectroscopy, high spatial resolution over a large field of view is often as important as high energy resolution, but current X-ray detectors do not provide both in the same device. Thermal Kinetic Inductance Detectors (TKIDs) are being developed as they offer a feasible way to combine the energy resolution of transition edge sensors with pixel counts approaching CCDs and thus promise significant improvements for many X-ray spectroscopy applications. TKIDs are a variation of Microwave Kinetic Inductance Detectors (MKIDs) and share their multiplexibility: working MKID arrays with 2024 pixels have recently been demonstrated and much bigger arrays are under development. In this work, we present a TKID prototype, which is able to achieve an energy resolution of 75 eV at 5.9 keV, even though its general design still has to be optimized. We further describe TKID fabrication, characterization, multiplexing, and working principle and demonstrate the necessity of a data fitting algorithm in order to extract photon energies. With further design optimizations, we expect to be able to improve our TKID energy resolution to less than 10 eV at 5.9 keV.

  20. Highly Multiplexible Thermal Kinetic Inductance Detectors for X-Ray Imaging Spectroscopy

    CERN Document Server

    Ulbricht, Gerhard; Szypryt, Paul; Walter, Alex B; Bockstiegel, Clint; Bumble, Bruce

    2015-01-01

    For X-ray imaging spectroscopy, high spatial resolution over a large field of view is often as important as high energy resolution, but current X-ray detectors do not provide both in the same device. Thermal Kinetic Inductance Detectors (TKIDs) are being developed as they offer a feasible way to combine the energy resolution of transition edge sensors with pixel counts approaching CCDs and thus promise significant improvements for many X-ray spectroscopy applications. TKIDs are a variation of Microwave Kinetic Inductance Detectors (MKIDs) and share their multiplexibility: working MKID arrays with 2024 pixels have recently been demonstrated and much bigger arrays are under development. In this work, we present our first working TKID prototypes which are able to achieve an energy resolution of 75 eV at 5.9 keV, even though their general design still has to be optimized. We further describe TKID fabrication, characterization, multiplexing and working principle and demonstrate the necessity of a data fitting algo...

  1. Design and experimental study of a two-dimensional position sensitive X-ray detector

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A prototype of a two-dimensional position sensitive X-ray detector was designed and constructed for small angle X-ray scattering experiments at BSFR (Beijing Synchrotron Radiation Facility). The detector is based on MWPC with cathode strip readout, and has a sensitive area of 200 mmx200 mm. The spatial resolution (FWHM) of about 210 μm along the anode wire direction was obtained from the 55Fe X-ray test of the detector.

  2. A vacuum photoemission detector for X-ray tomography on the ITER facility

    NARCIS (Netherlands)

    Barykov, IA; Gott, YV; Stepanenko, MM

    2004-01-01

    A vacuum photoemission detector designed for plasma tornography in X rays on the ITER facility is described. Such detectors allow X rays to be detected in the presence of intense neutron and gamma-photon fluxes. The results of tests of a prototype of this detector on a Co-60 source of gamma rays, it

  3. X-ray detector for automatic exposure control using ionization chamber filled with xenon gas

    CERN Document Server

    Nakagawa, A; Yoshida, T

    2003-01-01

    This report refers to our newly developed X-ray detector for reliable automatic X-ray exposure control, which is to be widely used for X-ray diagnoses in various clinical fields. This new detector utilizes an ionization chamber filled with xenon gas, in contrast to conventional X-ray detectors which use ionization chambers filled with air. Use of xenon gas ensures higher sensitivity and thinner design of the detector. The xenon gas is completely sealed in the chamber, so that the influence of the changes in ambient environments is minimized. (author)

  4. A technique for the absolute measurement of the W-value for X-rays in counting gases

    Energy Technology Data Exchange (ETDEWEB)

    Vinagre, F.L.R. E-mail: fleonor@saturno.fis.uc.pt; Conde, C.A.N

    2000-08-11

    A technique was developed for the absolute measurement of the W-value (the mean energy for the production of an electron-ion pair) for low-energy X-rays in a wide range of gases at atmospheric pressures, with a standard uncertainty better than 1%. This technique is based on the absolute measurement of the primary ionization charge produced by X-ray photons from a constant intensity monoenergetic X-ray source, e.g. a long lifetime radioactive source. The ionization charge is calibrated by the number of X-ray photons absorbed in the gas, counted with a photon detector. For this purpose, a hybrid detector system was tested and its use in W-value measurements was investigated. The technique was applied to pure xenon at 825 Torr with 5.9 keV X-rays and a W-value of 21.61{sub -0.10}{sup +0.14} eV was obtained for a 68% confidence level. The required corrections and the different factors contributing to the accuracy of the results are discussed. The advantages and limitations of this technique are explored and future developments are discussed.

  5. Development of gas microstrip detectors for digital x-ray imaging and radiation dosimetry

    CERN Document Server

    Dixit, M S; Dubeau, J; Gobbi, D G; Johns, P C; Karlen, Dean A; Oakham, F G; Waker, A J

    1998-01-01

    Our recent work in the application of gas microstrip detector (GMD) technology to the fields of digital X-ray imaging and radiation dosimetry Is described. The GMD can measure the position and the energy of individual photons at the high counting rates encountered in X-ray imaging. GMD-based imaging systems have high detective quantum efficiency and permit improvement of image quality and contrast using display windowing and measured energy information. Results are presented on the performance of a prototype GMD imaging system operated with a xenon/methane 90/10 gas mixture at 1 atm. Results are also presented on the performance of a GMD filled with tissue equivalent gases for applications in the field of radiation dosimetry in mixed neutron and gamma fields. The results show that the GMD can be used for dosimetric discrimination between different types of radiation in mixed-field environments.

  6. Replacement of monochromator and proportional gas counter by mercuric iodide detector in X-ray powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Nissenbaum, J.; Levi, A.; Burger, A.; Schieber, M. (Hebrew Univ., Jerusalem (Israel). School of Applied Science and Technology)

    1983-02-01

    Low resolution and therefore low-cost mercuric iodide detectors have successfully been applied to replace the combination of a graphite monochromator and a proportional gas radiation counter used in X-ray diffractometers. The mercuric iodide detector requires a lower DC bias of only 200 V rather than the 1500 V bias needed for the proportional gas counter. The much better stopping power of HgI/sub 2/ allows higher counting efficiency and therefore a better signal-to-noise ratio. Results are shown for X-ray powder diffractions of polycrystalline cubic silicon and tetragonal HgI/sub 2/.

  7. Novel X-ray Communication Based XNAV Augmentation Method Using X-ray Detectors

    Directory of Open Access Journals (Sweden)

    Shibin Song

    2015-09-01

    Full Text Available The further development of X-ray pulsar-based NAVigation (XNAV is hindered by its lack of accuracy, so accuracy improvement has become a critical issue for XNAV. In this paper, an XNAV augmentation method which utilizes both pulsar observation and X-ray ranging observation for navigation filtering is proposed to deal with this issue. As a newly emerged concept, X-ray communication (XCOM shows great potential in space exploration. X-ray ranging, derived from XCOM, could achieve high accuracy in range measurement, which could provide accurate information for XNAV. For the proposed method, the measurement models of pulsar observation and range measurement observation are established, and a Kalman filtering algorithm based on the observations and orbit dynamics is proposed to estimate the position and velocity of a spacecraft. A performance comparison of the proposed method with the traditional pulsar observation method is conducted by numerical experiments. Besides, the parameters that influence the performance of the proposed method, such as the pulsar observation time, the SNR of the ranging signal, etc., are analyzed and evaluated by numerical experiments.

  8. Novel X-ray Communication Based XNAV Augmentation Method Using X-ray Detectors.

    Science.gov (United States)

    Song, Shibin; Xu, Luping; Zhang, Hua; Bai, Yuanjie

    2015-09-03

    The further development of X-ray pulsar-based NAVigation (XNAV) is hindered by its lack of accuracy, so accuracy improvement has become a critical issue for XNAV. In this paper, an XNAV augmentation method which utilizes both pulsar observation and X-ray ranging observation for navigation filtering is proposed to deal with this issue. As a newly emerged concept, X-ray communication (XCOM) shows great potential in space exploration. X-ray ranging, derived from XCOM, could achieve high accuracy in range measurement, which could provide accurate information for XNAV. For the proposed method, the measurement models of pulsar observation and range measurement observation are established, and a Kalman filtering algorithm based on the observations and orbit dynamics is proposed to estimate the position and velocity of a spacecraft. A performance comparison of the proposed method with the traditional pulsar observation method is conducted by numerical experiments. Besides, the parameters that influence the performance of the proposed method, such as the pulsar observation time, the SNR of the ranging signal, etc., are analyzed and evaluated by numerical experiments.

  9. Hard X-ray Detector (HXD) on Board Suzaku

    CERN Document Server

    Takahashi, T; Endo, M; Endo, Y; Ezoe, Y; Fukazawa, Y; Hamaya, M; Hirakuri, S; Hong, S; Horii, M; Inoue, H; Isobe, N; Itoh, T; Iyomoto, N; Kamae, T; Kasama, D; Kataoka, J; Kato, H; Kawaharada, M; Kawano, N; Kawashima, K; Kawasoe, S; Kishishita, T; Kitaguchi, T; Kobayashi, Y; Kokubun, M; Kotoku, J; Kouda, M; Kubota, A; Kuroda, Y; Madejski, G; Makishima, K; Masukawa, K; Matsumoto, Y; Mitani, T; Miyawaki, R; Mizuno, T; Mori, K; Mori, M; Murashima, M; Murakami, T; Nakazawa, K; Niko, H; Nomachi, M; Okada, Y; Ohno, M; Oonuki, K; Ota, N; Ozawa, H; Sato, G; Shinoda, S; Sugiho, M; Suzuki, M; Taguchi, K; Takahashi, H; Takahashi, I; Takeda, S; Tamura, K; Tamura, T; Tanaka, T; Tanihata, C; Tashiro, M; Terada, Y; Tominaga, S; Uchiyama, Y; Watanabe, S; Yamaoka, K; Yanagida, T; Yonetoku, D

    2006-01-01

    The Hard X-ray Detector (HXD) on board Suzaku covers a wide energy range from 10 keV to 600 keV by combination of silicon PIN diodes and GSO scintillators. The HXD is designed to achieve an extremely low in-orbit back ground based on a combination of new techniques, including the concept of well-type active shield counter. With an effective area of 142 cm^2 at 20 keV and 273 cm2 at 150 keV, the background level at the sea level reached ~1x10^{-5} cts s^{-1} cm^{-2} keV^{-1} at 30 keV for the PI N diodes, and ~2x10^{-5} cts s^{-1} cm^{-2} keV^{-1} at 100 keV, and ~7x10^{-6} cts s^{-1} cm^{-2} keV^{-1} at 200 keV for the phoswich counter. Tight active shielding of the HXD results in a large array of guard counters surrounding the main detector parts. These anti-coincidence counters, made of ~4 cm thick BGO crystals, have a large effective area for sub-MeV to MeV gamma-rays. They work as an excellent gamma-ray burst monitor with limited angular resolution (~5 degree). The on-board signal-processing system and th...

  10. Temporal artifacts in flat dynamic x-ray detectors

    Science.gov (United States)

    Overdick, Michael; Solf, Torsten; Wischmann, Hans-Aloys

    2001-06-01

    Flat X-ray detectors based on CsI:Tl scintillators and amorphous silicon photodiodes are known to exhibit temporal artefacts (ghost images) which decay over time. Previously, these temporal artefacts have been attributed mainly to residual signals from the amorphous silicon photodiodes. More detailed experiments presented here show that a second class of effects, the so-called gain effects, also contributes significantly to the observed temporal artefacts. Both the residual signals and the photodiode gain effect have been characterized under various exposure conditions in the study presented here. The results of the experiments quantitatively show the decay of the temporal artefacts. Additionally, the influence of the detector's reset light on both effects in the photodiode has been studied in detail. The data from the measurements is interpreted based on a simple trapping model which suggests a strong link between the photodiode residual signals and the photodiode gain effect. For the residual signal effect a possible correction scheme is described. Furthermore, the relevance of the remaining temporal artefacts for the applications is briefly discussed for both the photodiode residual signals and the photodiode gain effect.

  11. Cooled CdZnTe detectors for X-ray astronomy

    CERN Document Server

    Bale, G; Seller, P; Lowe, B

    1999-01-01

    Recent results combining thermoelectrically cooled CdZnTe detectors with a low-noise Pentafet preamplifier are presented. Cooling between -30 deg. C and -40 deg. C reduces the leakage current of the detectors and allows the use of a pulsed reset preamplifier and long shaping times, significantly improving the energy resolution. Mn K subalpha X-rays at 5.9 keV have been observed with a resolution of less than 280 eV FWHM and a peak to background of more than 200:1. The Fano factor of the material has been estimated at 0.11+-0.012 at -40 deg. C. The detector requirement for X-ray astronomy will be a photon-counting imaging spectrometer. A 16x16 element, bump bonded pixel detector is described and results from a prototype silicon array presented. The detector is constructed with ASIC amplifiers with a system noise of <25 electrons rms and should give an energy resolution comparable to the Pentafet results presented here.

  12. Performance and limitations of high granularity single photon processing X-ray imaging detectors

    CERN Document Server

    Tlustos, L

    2005-01-01

    Progress in CMOS technology and in fine pitch bump bonding has made possible the development of single photon counting detectors for X-ray imaging with pixel pitches on the order of 50 µm giving a spatial resolution which is comparable to conventional CCD and flat panel detectors. This thesis studies the interaction of X-ray photons in the energy range of 5 keV to 70 keV with various sensor materials as well as the response of the Medipix2 readout system to both monochromatic and wide spectrum X-ray sources. Single photon processing offers the potential for spectroscopic imaging. However, this thesis demonstrates using simulations and measurements that the charge deposition and collection within the semiconductor sensor impose fundamental limits on the achievable energy resolution. In particular the discussion of charge during collection in the sensor and the generation of fluorescence photons in heavier sensor materials contribute to the appearance of a low energy tail on the detected spectrum of an incomin...

  13. Advances in the development of encapsulants for mercuric iodide X-ray detectors

    OpenAIRE

    Iwanczyk, J. S.; Wang, Y.J.; Bradley, J. G.; Albee, A. L.; Schnepple, W. F.

    1990-01-01

    Advances in the development of protective impermeable encapsulants with high transparency to ultra-low-energy X-rays for use on HgI_2 X-ray detectors are reported. Various X-ray fluorescence spectra from coated detectors are presented. The X-ray absorption in the encapsulants has been analyzed using characteristic radiation from various elements. Results suggest that low-energy cutoffs for the detectors are not determined solely by the encapsulating coatings presently employed but are also in...

  14. A large area position sensitive X-ray detector for astrophysical observations

    NARCIS (Netherlands)

    Mels, W.A.; Lowes, P.; Buurmans, H.B.; Brinkman, A.C.; Naber, A.P.; Rook, A.

    1988-01-01

    A large area position sensitive X-ray detector has been developed for use in the coded mask imaging X-ray spectrometer (COMIS) aboard the USSR research module KVANT. The module was launched on March 31, 1987. The detector, having a sensitive area of 256 × 256 mm2, is a sealed multiwire proportional

  15. Simulation of one-dimensionally polarized X-ray semiconductor detectors

    NARCIS (Netherlands)

    Engel, K.J.; Herrmann, C.

    2011-01-01

    Abstract: A pixelated X-ray semiconductor detector (=“direct converter”) is studied which contains an inhomogeneous electric field parallel to the depth axis caused by different concentrations of p- or n-doping. The X-ray energy deposition and charge movement within the detector is modeled in Monte-

  16. Tritium measurement in water using bremsstrahlung X-rays and a silicon drift detector

    Energy Technology Data Exchange (ETDEWEB)

    Niemes, Simon [Karlsruhe Institut of Technology, Institute for Technical Physics - Tritium Laboratory, Karlsruhe (Germany)

    2013-07-01

    Applications like future fusion plants or scientific experiments like KATRIN need a closed tritium infrastructure to cycle and handle tritium safely. At some process stages tritiated water (HTO) is generated, making measuring the tritium content in HTO vital for process control, accountancy and safety. There are several methods used to measure HTO, primarily Liquid Scintillation Counting (LSC). A new technique promising fast, in-line and wasteless measurement compared to LSC is the Beta Induced X-ray Spectroscopy (BIXS). The principle of BIXS is detecting the bremsstrahlung spectrum from the decelerated decay electrons in water and calibrate it to known concentrations. A novel approach utilizing a Silicon Drift Detector (SDD) to measure the emitted X-ray spectrum has several advantages over other detector types like scintillation counters. A SDD is a semiconductor detector with very low noise and good energy resolution, suitable for detecting the low intensity, low energy signal from BIXS. In this talk an overview of the experimental setup and detector is given, and first results are presented.

  17. Preliminary Results for LP VPE X-Ray Detectors

    OpenAIRE

    Adams, R; Bates, R.; Da Via, C.; Johnson, N.P.; O'Shea, V.; Pickford, A.; Raine, C.; Smith, K.

    1997-01-01

    Thick epitaxial layers have been grown using Low Pressure Vapour Phase Epitaxy techniques with low free carrier concentrations . This type of material is attractive as a medium for X-ray detection, because of its high conversion efficiency for X-rays in the medically interesting energy range.

  18. Low-energy shelf response in thin energy-dispersive X-ray detectors from Compton scattering of hard X-rays

    Science.gov (United States)

    Michel-Hart, N.; Elam, W. T.

    2017-08-01

    Silicon drift detectors have been successfully employed in both soft and hard X-ray spectroscopy. The response function to incident radiation at soft X-ray levels has been well studied and modeled, but less research has been published on response functions for these detectors to hard X-ray input spectra above 20 keV. When used with hard X-ray sources a significant low energy, non-peak response exists which can adversely affect detection limits for lighter elements in, for example, X-ray fluorescence spectroscopy. We present a numerical model that explains the non-peak response function of silicon drift detectors to hard X-rays based on incoherent Compton scattering within the detector volume. Experimental results are presented and numerically compared to model results.

  19. HEXITEC: A next generation hard X-ray Detector for Solar Observations

    Science.gov (United States)

    Panessa, M.; Christe, S.; Shih, A.; Gaskin, J.; Wilson, M. D.; Seller, P.; Baumgartner, W.; Inglis, A. R.

    2015-12-01

    High angular resolution HXR optics require detectors with a large number of fine pixels in order to adequately sample the telescope point spread function (PSF) over the entire field of view. Recent developments at the Rutherford Appleton Laboratory (RAL) have resulted in a new hard X-ray (HXR) detector system with the smallest independent pixels currently available, 250 microns. This matches perfectly with the best angular resolution currently achievable by HXR focusing optics which is about 5 arcsec (FWHM). For a SMEX mission with a 15 meter focal length each pixel would cover an angular size of about 3 arcsec thereby subsampling the PSF. Dubbed HEXITEC, for High Energy X-Ray Imaging Technology, this Application Specific Integrated Circuit (ASIC), can be bonded to 1- or 2- mm-thick Cadmium Telluride (CdTe) or Cadmium-Zinc-Telluride (CZT) which provide high efficiency in the HXR region, good energy resolution, low background, low power, and low sensitivity to radiation damage. For solar observations, the ability to handle high counting rates is also extremely desirable. This ASIC can read each pixel 10,000 times per second. The NASA Marshall Space Flight Center (MSFC) and the Goddard Space Flight Center (GSFC) has been working with RAL over the past few years to develop these detectors to be used with HXR focusing telescopes. We present recent progress on this development effort and its capabilities as applied to solar observations.

  20. Shimming with permanent magnets for the x-ray detector in a hybrid x-ray/ MR system.

    Science.gov (United States)

    Wen, Zhifei; Fahrig, Rebecca; Williams, Scott T; Pelc, Norbert J

    2008-09-01

    In this x-ray/MR hybrid system an x-ray flat panel detector is placed under the patient cradle, close to the MR volume of interest (VOI), where the magnetic field strength is approximately 0.5 T. Immersed in this strong field, several electronic components inside the detector become magnetized and create an additional magnetic field that is superimposed on the original field of the MR scanner. Even after linear shimming, the field homogeneity of the MR scanner remains disrupted by the detector. The authors characterize the field due to the detector with the field of two magnetic dipoles and further show that two sets of permanent magnets (NdFeB) can withstand the main magnetic field and compensate for the nonlinear components of the additional field. The ideal number of magnets and their locations are calculated based on a field map measured with the detector in place. Experimental results demonstrate great promise for this technique, which may be useful in many settings where devices with magnetic components need to be placed inside or close to an MR scanner.

  1. A new X-ray detector for magnetic circular dichroism experiments

    CERN Document Server

    Bateman, J E; Dudzik, E; Laan, G V D; Lipp, J D; Smith, A D; Stephenson, R

    2001-01-01

    X-ray magnetic circular dichroism (XMCD) studies of magnetic 3d transition metal samples require the recording of high quality absorption scans in high magnetic fields using circularly polarised soft X-rays of energies in the range 0.5-1 keV. A Gas Microstrip Detector is described which permits the option of using the X-ray fluorescence signal instead of the usual electron yield signal.

  2. 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.

  3. 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.

  4. Multi-energy x-ray detectors to improve air-cargo security

    Science.gov (United States)

    Paulus, Caroline; Moulin, Vincent; Perion, Didier; Radisson, Patrick; Verger, Loïck

    2017-05-01

    X-ray based systems have been used for decades to screen luggage or cargo to detect illicit material. The advent of energy-sensitive photon-counting x-ray detectors mainly based on Cd(Zn)Te semi-conductor technology enables to improve discrimination between materials compared to single or dual energy technology. The presented work is part of the EUROSKY European project to develop a Single European Secure Air-Cargo Space. "Cargo" context implies the presence of relatively heavy objects and with potentially high atomic number. All the study is conducted on simulations with three different detectors: a typical dual energy sandwich detector, a realistic model of the commercial ME100 multi-energy detector marketed by MULTIX, and a ME100 "Cargo": a not yet existing modified multi-energy version of the ME100 more suited to air freight cargo inspection. Firstly, a comparison on simulated measurements shows the performances improvement of the new multi-energy detectors compared to the current dual-energy one. The relative performances are evaluated according to different criteria of separability or contrast-to-noise ratio and the impact of different parameters is studied (influence of channel number, type of materials and tube voltage). Secondly, performances of multi-energy detectors for overlaps processing in a dual-view system is accessed: the case of orthogonal projections has been studied, one giving dimensional values, the other one providing spectral data to assess effective atomic number. A method of overlap correction has been proposed and extended to multi-layer objects case. Therefore, Calibration and processing based on bi-material decomposition have been adapted for this purpose.

  5. MeV X-ray imaging using plastic scintillating fiber area detectors: a simulation study.

    Science.gov (United States)

    Tang, Shi-Biao; Ma, Qingli; Yin, Zejie; Zhu, Daming

    2008-02-01

    Due to their low cost, flexibility, and convenience for long distance data transfer, plastic scintillating fibers (PSFs) have been increasingly used in building detectors or sensors for detecting various radiations and imaging. In this work, the possibility of using PSF coupled with charge-coupled devices (CCD) to build area detectors for X-ray imaging is studied using a Monte Carlo simulation. The focus is on X-ray imaging with energy from a few 100 keV to about 20 MeV. It is found that the efficiency of PSF in detecting X-ray in this energy range is low. The performance can be improved by coating a PSF with X-ray absorption layers and the MTF of the system is presented. It seems possible to build such area detectors with PSFs for imaging hard X-rays under certain environment.

  6. Relative calibration of energy thresholds on multi-bin spectral x-ray detectors

    Science.gov (United States)

    Sjölin, M.; Danielsson, M.

    2016-12-01

    Accurate and reliable energy calibration of spectral x-ray detectors used in medical imaging is essential for avoiding ring artifacts in the reconstructed images (computed tomography) and for performing accurate material basis decomposition. A simple and accurate method for relative calibration of the energy thresholds on a multi-bin spectral x-ray detector is presented. The method obtains the linear relations between all energy thresholds in a channel by scanning the thresholds with respect to each other during x-ray illumination. The method does not rely on a model of the detector's response function and does not require any identifiable features in the x-ray spectrum. Applying the same method, the offset between the thresholds can be determined also without external stimuli by utilizing the electronic noise as a source. The simplicity and accuracy of the method makes it suitable for implementation in clinical multi-bin spectral x-ray imaging systems.

  7. Study on data acquisition circuit used in SSPA linear array detector X-ray detection

    CERN Document Server

    Wei Biao; Che Zhen Ping

    2002-01-01

    After SSPA used as X-ray array detector is developed, the authors take a research on the data acquisition circuit applied to the detector. The experiment designed has verified the feasibility of application of this array detector and its data acquisition circuit to X-ray computed tomography (X-CT). The preliminary test results indicate that the method of the X-ray detection is feasible for industry X-CT nondestructive testing, which brings about advantage for detecting and measuring with high resolution, good efficiency and low cost

  8. Sensitive X-ray detectors made of methylammonium lead tribromide perovskite single crystals

    NARCIS (Netherlands)

    Wei, Haotong; Fang, Yanjun; Mulligan, Padhraic; Chuirazzi, William; Fang, Hong-Hua; Wang, Congcong; Ecker, Benjamin R.; Gao, Yongli; Loi, Maria Antonietta; Cao, Lei; Huang, Jinsong

    2016-01-01

    The large mobilities and carrier lifetimes of hybrid perovskite single crystals and the high atomic numbers of Pb, I and Br make them ideal for X-ray and gamma-ray detection. Here, we report a sensitive X-ray detector made of methylammonium lead bromide perovskite single crystals. A record-high mobi

  9. Sensitive X-ray detectors made of methylammonium lead tribromide perovskite single crystals

    NARCIS (Netherlands)

    Wei, Haotong; Fang, Yanjun; Mulligan, Padhraic; Chuirazzi, William; Fang, Hong-Hua; Wang, Congcong; Ecker, Benjamin R.; Gao, Yongli; Loi, Maria Antonietta; Cao, Lei; Huang, Jinsong

    2016-01-01

    The large mobilities and carrier lifetimes of hybrid perovskite single crystals and the high atomic numbers of Pb, I and Br make them ideal for X-ray and gamma-ray detection. Here, we report a sensitive X-ray detector made of methylammonium lead bromide perovskite single crystals. A record-high mobi

  10. Optomechanical design of a high-precision detector robot arm system for x-ray nano-diffraction with x-ray nanoprobe

    Science.gov (United States)

    Shu, D.; Kalbfleisch, S.; Kearney, S.; Anton, J.; Chu, Y. S.

    2014-03-01

    Collaboration between Argonne National Laboratory and Brookhaven National Laboratory has created a design for the high-precision detector robot arm system that will be used in the x-ray nano-diffraction experimental station at the Hard X-ray Nanoprobe (HXN) beamline for the NSLS-II project. The robot arm system is designed for positioning and manipulating an x-ray detector in three-dimensional space for nano-diffraction data acquisition with the HXN x-ray microscope. It consists of the following major component groups: a granite base with air-bearing support, a 2-D horizontal base stage, a vertical axis goniometer, a 2-D vertical plane robot arm, a 3-D fast scanning stages group, and a 2-D x-ray pixel detector. The design specifications and unique optomechanical structure of this novel high-precision detector robot arm system will be presented in this paper.

  11. Imaging properties of small-pixel spectroscopic x-ray detectors based on cadmium telluride sensors.

    Science.gov (United States)

    Koenig, Thomas; Schulze, Julia; Zuber, Marcus; Rink, Kristian; Butzer, Jochen; Hamann, Elias; Cecilia, Angelica; Zwerger, Andreas; Fauler, Alex; Fiederle, Michael; Oelfke, Uwe

    2012-11-07

    Spectroscopic x-ray imaging by means of photon counting detectors has received growing interest during the past years. Critical to the image quality of such devices is their pixel pitch and the sensor material employed. This paper describes the imaging properties of Medipix2 MXR multi-chip assemblies bump bonded to 1 mm thick CdTe sensors. Two systems were investigated with pixel pitches of 110 and 165 μm, which are in the order of the mean free path lengths of the characteristic x-rays produced in their sensors. Peak widths were found to be almost constant across the energy range of 10 to 60 keV, with values of 2.3 and 2.2 keV (FWHM) for the two pixel pitches. The average number of pixels responding to a single incoming photon are about 1.85 and 1.45 at 60 keV, amounting to detective quantum efficiencies of 0.77 and 0.84 at a spatial frequency of zero. Energy selective CT acquisitions are presented, and the two pixel pitches' abilities to discriminate between iodine and gadolinium contrast agents are examined. It is shown that the choice of the pixel pitch translates into a minimum contrast agent concentration for which material discrimination is still possible. We finally investigate saturation effects at high x-ray fluxes and conclude with the finding that higher maximum count rates come at the cost of a reduced energy resolution.

  12. Performance of the micro-PIC gaseous area detector in small-angle X-ray scattering experiments.

    Science.gov (United States)

    Hattori, Kaori; Tsuchiya, Ken'ichi; Ito, Kazuki; Okada, Yoko; Fujii, Kotaro; Kubo, Hidetoshi; Miuchi, Kentaro; Takata, Masaki; Tanimori, Toru; Uekusa, Hidehiro

    2009-03-01

    The application of a two-dimensional photon-counting detector based on a micro-pixel gas chamber (micro-PIC) to high-resolution small-angle X-ray scattering (SAXS), and its performance, are reported. The micro-PIC is a micro-pattern gaseous detector fabricated by printed circuit board technology. This article describes the performance of the micro-PIC in SAXS experiments at SPring-8. A dynamic range of >10(5) was obtained for X-ray scattering from a polystyrene sphere solution. A maximum counting rate of up to 5 MHz was observed with good linearity and without saturation. For a diffraction pattern of collagen, weak peaks were observed in the high-angle region in one accumulation of photons.

  13. A CCD area detector for X-ray diffraction under high pressure for rotating anode source

    Indian Academy of Sciences (India)

    Amar Sinha; Alka B Garg; V Vijayakumar; B K Godwal; S K Sikka

    2000-04-01

    Details of a two-dimensional X-ray area detector developed using a charge coupled device, a image intensifier and a fibre optic taper are given. The detector system is especially optimized for angle dispersive X-ray diffraction set up using rotating anode generator as X-ray source. The performance of this detector was tested by successfully carrying out powder X-ray diffraction measurements on various materials such as intermetallics AuIn2, AuGa2, high material Pd and low scatterer adamantane (C10H16) at ambient conditions. Its utility for quick detection of phase transitions at high pressures with diamond anvil cell is demonstrated by reproducing the known pressure induced structural transitions in RbI, KI and a new structural phase transition in AuGa2 above 10 GPa. Various softwares have also been developed to analyze data from this detector.

  14. Basis material decomposition method for material discrimination with a new spectrometric X-ray imaging detector

    Science.gov (United States)

    Brambilla, A.; Gorecki, A.; Potop, A.; Paulus, C.; Verger, L.

    2017-08-01

    Energy sensitive photon counting X-ray detectors provide energy dependent information which can be exploited for material identification. The attenuation of an X-ray beam as a function of energy depends on the effective atomic number Zeff and the density. However, the measured attenuation is degraded by the imperfections of the detector response such as charge sharing or pile-up. These imperfections lead to non-linearities that limit the benefits of energy resolved imaging. This work aims to implement a basis material decomposition method which overcomes these problems. Basis material decomposition is based on the fact that the attenuation of any material or complex object can be accurately reproduced by a combination of equivalent thicknesses of basis materials. Our method is based on a calibration phase to learn the response of the detector for different combinations of thicknesses of the basis materials. The decomposition algorithm finds the thicknesses of basis material whose spectrum is closest to the measurement, using a maximum likelihood criterion assuming a Poisson law distribution of photon counts for each energy bin. The method was used with a ME100 linear array spectrometric X-ray imager to decompose different plastic materials on a Polyethylene and Polyvinyl Chloride base. The resulting equivalent thicknesses were used to estimate the effective atomic number Zeff. The results are in good agreement with the theoretical Zeff, regardless of the plastic sample thickness. The linear behaviour of the equivalent lengths makes it possible to process overlapped materials. Moreover, the method was tested with a 3 materials base by adding gadolinium, whose K-edge is not taken into account by the other two materials. The proposed method has the advantage that it can be used with any number of energy channels, taking full advantage of the high energy resolution of the ME100 detector. Although in principle two channels are sufficient, experimental measurements show

  15. Evaluation of controlled-drift detectors in X-ray spectroscopic imaging applications.

    Science.gov (United States)

    Castoldi, Andrea; Guazzoni, Chiara; Ozkan, Cigdem; Vedani, Giorgio; Hartmann, Robert; Bjeoumikhov, Aniouar

    2009-06-01

    A detector that looks promising for advanced imaging modalities--such as X-ray absorption contrast imaging, X-ray fluorescence imaging, and diffraction-enhanced imaging--is the controlled-drift detector (CDD). The CDD is a novel two-dimensional X-ray imager with energy resolving capability of spectroscopic quality. It is built on a fully depleted silicon wafer and features fast readout while being operated at or near room temperature. The use of CDDs in the aforementioned applications allows translating these techniques from synchrotron-based experiments to laboratory-size experiments using polychromatic X-ray generators. We have built a dedicated and versatile detection module based on a 36 mm2 CDD chip featuring pixels of 180 x 180 microm 2, and we evaluated the system performance in different X-ray imaging applications both with synchrotron-based experiments and in the laboratory environment.

  16. Effects of characteristic x rays on the noise power spectra and detective quantum efficiency of photoconductive x-ray detectors.

    Science.gov (United States)

    Zhao, W; Ji, W G; Rowlands, J A

    2001-10-01

    The effects of K fluorescence on the imaging performance of photoconductor-based x-ray imaging systems are investigated. A cascaded linear systems model was developed, where a parallel cascaded process was implemented to take into account the effect of K-fluorescence reabsorption on the modulation transfer function (MTF), noise power spectrum (NPS), and the spatial frequency dependent detective quantum efficiency [DQE(f)] of an imaging system. The investigation was focused on amorphous selenium (a-Se), which is the most highly developed photoconductor material for x-ray imaging. The results were compared to those obtained with Monte Carlo simulation using the same imaging condition and detector parameters, so that the validity of the cascaded linear system model could be confirmed. Our results revealed that K-fluorescence reabsorption in a-Se is responsible for a 18% drop in NPS at high spatial frequencies with an incident x-ray photon energy of E=20 keV (which is just above the K edge of 12.5 keV). When E increases to 60 keV, the effects of K-fluorescence reabsorption on NPS decrease to approximately 12% at high spatial frequencies. Because the high frequency drop is present in both MTF and NPS, the effect of K fluorescence on DQE(f) is minimal, especially for E that is much higher than the K edge. We also applied the cascaded linear system model to a newly developed compound photoconductor, lead iodide (PbI2), and found that at 60 keV there is a high frequency drop in NPS of 19%. The calculated NPS were compared to previously published measurements of PbI2 detectors.

  17. Energy resolution of a silicon detector with the RX64 ASIC designed for X-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-12-11

    Results from a silicon microstrip detector coupled to the RX64 ASIC are presented. The system is capable of single photon counting in digital X-ray imaging, with foreseen applications to dual energy mammography and angiography. The main features of the detecting system are low noise (operation with threshold as low as {approx}4 keV is possible), good spatial resolution (a pixel of 100 {mu}mx300 {mu}m when oriented edge-on) and good counting rate capability (up to one million counts per channel with a maximum rate of about 200 kHz per channel). The energy resolution of the system, as obtained with several fluorescence X-ray lines, is described.

  18. Calibration of a time-resolved hard-x-ray detector using radioactive sources

    Science.gov (United States)

    Stoeckl, C.; Theobald, W.; Regan, S. P.; Romanofsky, M. H.

    2016-11-01

    A four-channel, time-resolved, hard x-ray detector (HXRD) has been operating at the Laboratory for Laser Energetics for more than a decade. The slope temperature of the hot-electron population in direct-drive inertial confinement fusion experiments is inferred by recording the hard x-ray radiation generated in the interaction of the electrons with the target. Measuring the energy deposited by hot electrons requires an absolute calibration of the hard x-ray detector. A novel method to obtain an absolute calibration of the HXRD using single photons from radioactive sources was developed, which uses a thermoelectrically cooled, low-noise, charge-sensitive amplifier.

  19. 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...

  20. 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.

  1. The use of CdTe detectors for dental X-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Marcus Aurelio P. dos; Fragoso, Maria da Conceicao F.; Oliveira, Mercia L.; Lima, Ricardo de A.; Hazin, Clovis A. [Centro Regional de Ciencias Nucleares (CRCN/CNEN-PE), Recife, PE (Brazil)]. E-mails: masantos@cnen.gov.br; mariacc05@yahoo.com.br; mercial@cnen.gov.br; ralima@cnen.gov.br; chazin@cnen.gov.br

    2007-07-01

    he cadmium telluride (CdTe) semiconductor detector provides high detection efficiency for use in the diagnostic x-rays energy range, because of the high atomic number and high density of the crystal. Moreover, it has the great advantage of working at room temperature, in contrast to the germanium detector, which operates in liquid nitrogen temperature. The CdTe detector has been utilized in diagnostic x-ray spectroscopy, but only scarce information about its use in dental X-ray beams has been published. In this way, a portable 3x3x1 mm{sup 3} CdTe solid state detector (XR-100T CdTe by Amptek, Inc.) with tungsten pinhole collimators, alignment device and associated software was utilized in this work for measuring the photon spectra in the dental x-ray kVp range. A single-phase dental unit with adjustable kVp and mA was employed and the x-ray spectra were experimentally determined at 50, 60 and 70 kVp with 0.5 mA tube current. The pulse height distribution obtained with this detector, however, does not represent the 'true' photon spectra. For this reason, a stripping procedure was implemented to correct the distribution in order to determine the real photon spectra. The x-ray spectra obtained with the CdTe detector were compared with the ones measured with a high-purity germanium detector (EGP200-13-TR by Eurisys Mesures). The reasonable agreement between the results obtained with both detectors for the 50 to 70 keV range show that CdTe detectors can be utilized for dental x-ray spectrometry. (author)

  2. Evaluation of the energy dependence of a zinc oxide nanofilm X-ray detector

    Energy Technology Data Exchange (ETDEWEB)

    Valenca, C.P.V., E-mail: claudia.cpvv@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife (Brazil); Silveira, M.A.L.; Macedo, M.A., E-mail: odecamm@gmail.com [Universidade Federal de Sergipe (UFSE), Sao Cristovao, SE (Brazil); Santos, L.A.P, E-mail: lasantos@scients.com.br [Centro Regional de Ciencias Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2015-07-01

    International organizations of human health and radiation protection have recommended certain care for using of the X-ray as a diagnosis tool to avoid any type of radiological accident or overdose to the patient. This can be done assessing the parameters of the X-ray equipment and there are various types of detectors available for that: ionizing chamber, electronic semiconductor devices, etc. These detectors must be calibrated so that they can be used for any energy range and such a procedure is correlated with what is called the energy dependence of the detector. In accordance with the stated requirements of IEC 61267, the standard radiation quality beams and irradiation conditions (RQRs) are the tools and techniques for calibrating diagnostic X-Ray instruments and detectors. The purpose of this work is to evaluate the behavior of the energy dependence of a detector fabricated from a zinc oxide (ZnO) nanofilm. A Pantak industrial X-ray equipment was used to generate the RQR radiation quality beams and test three ZnO detector samples. A 6430 sub-femto-ammeter, Keithley, was used to bias the ZnO detector and simultaneously perform the output readings. The results showed that the ZnO device has some increase in its sensitivity to the ionizing radiation as the X-ray effective energy decreases unlike other types of semiconductor electronic devices typically used as an X-ray detector. We can conclude that the ZnO device can be used as a diagnostic X-ray detector with an appropriate calibration. (author)

  3. Characterization of a spectroscopic detector for application in x-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Dooraghi, A. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fix, B. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Smith, J. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brown, W. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Azevedo, S. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Martz, H. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-04-21

    Recent advances in cadmium telluride (CdTe) energy-discriminating pixelated detectors have enabled the possibility of Multi-Spectral X-ray Computed Tomography (MSXCT) to incorporate spectroscopic information into CT. MultiX ME 100 V2 is a CdTe-based spectroscopic x-ray detector array capable of recording energies from 20 to 160 keV in 1.1 keV energy bin increments. Hardware and software have been designed to perform radiographic and computed tomography tasks with this spectroscopic detector. Energy calibration is examined using the end-point energy of a bremsstrahlung spectrum and radioisotope spectral lines. When measuring the spectrum from Am-241 across 500 detector elements, the standard deviation of the peak-location and FWHM measurements are ±0.4 and ±0.6 keV, respectively. As these values are within the energy bin size (1.1 keV), detector elements are consistent with each other. The count rate is characterized, using a nonparalyzable model with a dead time of 64 ± 5 ns. This is consistent with the manufacturer’s quoted per detector-element linear-deviation at 2 Mpps (million photons per sec) of 8.9% (typical) and 12% (max). When comparing measured and simulated spectra, a low-energy tail is visible in the measured data due to the spectral response of the detector. If no valid photon detections are expected in the low-energy tail, then a background subtraction may be applied to allow for a possible first-order correction. If photons are expected in the low-energy tail, a detailed model must be implemented. A radiograph of an aluminum step wedge with a maximum height of about 20 mm shows an underestimation of attenuation by about 10% at 60 keV. This error is due to partial energy deposition from higher-energy (> 60 keV) photons into a lower-energy (~60 keV) bin, reducing the apparent attenuation. A radiograph of a PTFE cylinder taken using a bremsstrahlung spectrum from an x-ray voltage of 100 kV filtered by 1.3 mm Cu is reconstructed using Abel inversion

  4. Influence of backscattering on the spatial resolution of semiconductor X-ray detectors

    Science.gov (United States)

    Hoheisel, M.; Korn, A.; Giersch, J.

    2005-07-01

    Pixelated X-ray detectors using semiconductor layers or scintillators as absorbers are widely used in high-energy physics, medical diagnosis, or non-destructive testing. Their good spatial resolution performance makes them particularly suitable for applications where fine details have to be resolved. Intrinsic limitations of the spatial resolution have been studied in previous simulations. These simulations focused on interactions inside the conversion layer. Transmitted photons were treated as a loss. In this work, we also implemented the structure behind the conversion layer to investigate the impact of backscattering inside the detector setup. We performed Monte Carlo simulations with the program ROSI ( Roentgen Simulation) which is based on the well-established EGS4 algorithm. Line-spread functions of different fully implemented detectors were simulated. In order to characterize the detectors' spatial resolution, the modulation transfer functions (MTF) were calculated. The additional broadening of the line-spread function by carrier transport has been ignored in this work. We investigated two different detector types: a directly absorbing pixel detector where a semiconductor slab is bump-bonded to a readout ASIC such as the Medipix-2 setup with Si or GaAs as an absorbing semiconductor layer, and flat-panel detectors with a Se or a CsI converter. We found a significant degradation of the MTF compared to the case without backscattering. At energies above the K-edge of the backscattering material the spatial resolution drops and can account for the observed low-frequency drop of the MTF. Ignoring this backscatter effect might lead to misinterpretations of the charge sharing effect in counting pixel detectors.

  5. Wire transfer function analysis for castellated dual-energy x-ray detectors.

    Science.gov (United States)

    Chan, Jer Wang; Evans, James Paul Owain; Yong, Yen San; Monteith, Andrew

    2004-12-10

    An investigation into the spatial resolving power of a castellated linear dual-energy x-ray detector array is reported. The detector was developed for use in aviation security screening applications. Experiments employing different gauges of lead wire are used to plot a wire transfer function. A numerical simulation is developed to predict and underpin the empirical results. The suitable processing of the castellated detector signals helps to maintain spatial resolving power while affording a 50% reduction in x-ray sensing elements. This encouraging result has formed the basis for an ongoing investigation into materials discrimination capability of the castellated detector array.

  6. Place of HgI/sub 2/ energy-dispersive x-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Dabrowski, A.J.; Huth, G.C.; Iwanczyk, J.S.; Kusmiss, J.H.; Barton, J.S.; Szymczyk, J.M.; Schnepple, W.F.; Lynn, R.

    1982-01-01

    After a review of solid-state conduction counters, in general, and of the history of mercuric iodide, in particular, the theory of operation of solid-state energy-dispersive HgI/sub 2/ detectors is dicusssed. The main factors which limit energy resolution in solid-state compound detectors are considered, including statistical fluctuations in charge generation, the window effect, trapping, inhomogeneities in the detector material, and electronic noise. Potential applications of room-temperature HgI/sub 2/ x-ray detectors are listed, and general considerations are discussed for x-ray fluorescence analysis with HgI/sub 2/. Directions of current investigations are given. (LEW)

  7. 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.

  8. Versatile, reprogrammable area pixel array detector for time-resolved synchrotron x-ray applications

    Energy Technology Data Exchange (ETDEWEB)

    Gruner, Sol [Cornell Univ., Ithaca, NY (United States)

    2010-05-01

    The final technical report for DOE grant DE-SC0004079 is presented. The goal of the grant was to perform research, development and application of novel imaging x-ray detectors so as to effectively utilize the high intensity and brightness of the national synchrotron radiation facilities to enable previously unfeasible time-resolved x-ray research. The report summarizes the development of the resultant imaging x-ray detectors. Two types of detector platforms were developed: The first is a detector platform (called a Mixed-Mode Pixel Array Detector, or MM-PAD) that can image continuously at over a thousand images per second while maintaining high efficiency for wide dynamic range signals ranging from 1 to hundreds of millions of x-rays per pixel per image. Research on an even higher dynamic range variant is also described. The second detector platform (called the Keck Pixel Array Detector) is capable of acquiring a burst of x-ray images at a rate of millions of images per second.

  9. Integration of flat panel X-ray detector for high resolution diagnostic medical imaging

    Science.gov (United States)

    Kim, Min-Woo; Yun, Min-Seok; Kim, Yoon-Suk; Oh, Kyung-Min; Shin, Jung-Wook; Nam, Kyung-Tae; Nam, Sang-Hee

    2011-05-01

    In these days, flat panel X-ray image detectors have shown their potential for replacing traditional screen-film systems. To detect the X-ray photon energy, there are two main methods known as a direct method and an indirect method. The X-rays are converted immediately into electrical signal with the direct method. The indirect method has two conversion steps: the scintillator absorbs the X-rays and converts them to visible light. And then the visible light is converted to electrical signal (e.g. by photodiodes). In this work, the flat panel digital X-ray image detector based on direct method with a high atomic number material was designed and evaluated. The high atomic number material for X-ray conversion is deposited by a rubbing method with about 300 μm. The rubbing method is similar to the screen printing method. It consists of two elements: the screen and the squeegee. The method uses a proper stiff bar stretched tightly over a frame made of wood or metal. Proper tension is essential for proper laminated structure. The detector prototype has 139 μm pixel pitch, total 1280×1536 pixels and 86% fill factor. Twelve readout ICs are installed on digital X-ray detector and simultaneously operated to reach short readout time. The electronics integrated: the preamplifier to amplify generated signal, the Analog to Digital converter and the source of bias voltage (1 V/μm). The system board and interface use an NI-camera program. Finally, we achieved images from this flat panel X-ray image detector.

  10. The PASERO Project: parallel and serial readout systems for gas proportional synchrotron radiation X-ray detectors

    CERN Document Server

    Koch, M H J; Briquet-Laugier, F; Epstein, A; Sheldon, S; Beloeuvre, E; Gabriel, A; Hervé, C; Kocsis, M; Koschuch, A; Laggner, P; Leingartner, W; Raad-Iseli, C D; Reimann, T; Golding, F; Torki, K

    2001-01-01

    A project aiming at producing more efficient position sensitive gas proportional detectors and readout systems is presented. An area detector with reduced electrode spacing and a spatial resolution of 0.5 mm and two time to digital convertors (TDC) based on ASICs were produced. The first TDC, intended for use with linear detectors, relies on time to space conversion, whereas the second one, for area detectors, uses a ring oscillator with a phase locked loop. A parallel readout system for multi-anode detectors aiming at a maximum count rate extensively uses RISC microcontrollers. An electronic simulator of linear detectors built for test purposes and a mechanical chopper used for attenuation of the X-ray beam are also briefly described.

  11. Directly-deposited blocking filters for high-performance silicon x-ray detectors

    Science.gov (United States)

    Bautz, M.; Kissel, S.; Masterson, R.; Ryu, K.; Suntharalingam, V.

    2016-07-01

    Silicon X-ray detectors often require blocking filters to mitigate noise and out-of-band signal from UV and visible backgrounds. Such filters must be thin to minimize X-ray absorption, so direct deposition of filter material on the detector entrance surface is an attractive approach to fabrication of robust filters. On the other hand, the soft (E X-ray spectral resolution of the detector is sensitive to the charge collection efficiency in the immediate vicinity of its entrance surface, so it is important that any filter layer is deposited without disturbing the electric field distribution there. We have successfully deposited aluminum blocking filters, ranging in thickness from 70 to 220nm, on back-illuminated CCD X-ray detectors passivated by means of molecular beam epitaxy. Here we report measurements showing that directly deposited filters have little or no effect on soft X-ray spectral resolution. We also find that in applications requiring very large optical density (> OD 6) care must be taken to prevent light from entering the sides and mounting surfaces of the detector. Our methods have been used to deposit filters on the detectors of the REXIS instrument scheduled to fly on OSIRIS-ReX later this year.

  12. Compensational scintillation detector with a flat energy response for flash X-ray measurements

    Science.gov (United States)

    Chen, Liang; Ouyang, Xiaoping; Liu, Bin; Liu, Jinliang; Quan, Lin; Zhang, Zhongbing

    2013-01-01

    To measure the intensity of flash X-ray sources directly, a novel scintillation detector with a fast time response and flat energy response is developed by combining film scintillators of doped ZnO crystal and fast organic scintillator together. Through compensation design, the dual-scintillator detector (DSD) achieved a flat energy response to X-rays from tens of keV to several MeV, and sub-nanosecond time response by coupling to ultrafast photo-electronic devices. A prototype detector was fabricated according to the theoretical design; it employed ZnO:In and EJ228 with thicknesses of 0.3 mm and 0.1 mm, respectively. The energy response of this detector was tested on monoenergetic X-ray and γ-ray sources. The detector performs very well with a sensitivity fluctuation below 5% for 8 discrete energy points within the 40-250 keV energy region and for other energies of 662 keV and 1.25 MeV as well, showing good accordance with the theoretical design. Additionally, the detector works properly for the application to the flash X-ray radiation field absolute intensity measurement. This DSD may be very useful for the diagnosis of time-resolved dynamic physical processes of flash X-ray sources without knowing the exact energy spectrum.

  13. Charge Summing in Spectroscopic X-Ray Detectors With High-Z Sensors

    CERN Document Server

    Koenig, Thomas; Cecilia, Angelica; Ballabriga, Rafael; Baumbach, Tilo; Llopart, Xavier; Fiederle, Michael; Zuber, Marcus; Hamann, Elias; Fauler, Alex; Campbell, Michael

    2013-01-01

    The spectroscopic performance of photon counting detectors is limited by the effects of charge sharing between neighboring pixels and the emission of characteristic X-rays. For these reasons, an event can be either missed or counted more than once. These effects become more and more of a concern when pixel pitches are reduced, and for the technology available so far, this meant that there would always be a trade-off between a high spatial and a high spectral resolution. In this work, we present first measurements obtained with the new Medipix3RX ASIC, which features a network of charge summing circuits establishing a communication between pixels which helps to mitigate these effects. Combined with cadmium telluride sensors, we show that this new technology is successful at improving a detector's spectroscopic capabilities even at pixel pitches as small as 55 mu m. At this pitch, we measure an energy response function similar to that observed for a pixel pitch of 165 mu m in the absence of a charge summing cir...

  14. Comparison of natural and synthetic diamond X-ray detectors.

    Science.gov (United States)

    Lansley, S P; Betzel, G T; Metcalfe, P; Reinisch, L; Meyer, J

    2010-12-01

    Diamond detectors are particularly well suited for dosimetry applications in radiotherapy for reasons including near-tissue equivalence and high-spatial resolution resulting from small sensitive volumes. However, these detectors have not become commonplace due to high cost and poor availability arising from the need for high-quality diamond. We have fabricated relatively cheap detectors from commercially-available synthetic diamond fabricated using chemical vapour deposition. Here, we present a comparison of one of these detectors with the only commercially-available diamond-based detector (which uses a natural diamond crystal). Parameters such as the energy dependence and linearity of charge with dose were investigated at orthovoltage energies (50-250 kV), and dose-rate dependence of charge at linear accelerator energy (6 MV). The energy dependence of a synthetic diamond detector was similar to that of the natural diamond detector, albeit with slightly less variation across the energy range. Both detectors displayed a linear response with dose (at 100 kV) over the limited dose range used. The sensitivity of the synthetic diamond detector was 302 nC/Gy, compared to 294 nC/Gy measured for the natural diamond detector; however, this was obtained with a bias of 246.50 V compared to a bias of 61.75 V used for the natural diamond detector. The natural diamond detector exhibited a greater dependency on dose-rate than the synthetic diamond detector. Overall, the synthetic diamond detector performed well in comparison to the natural diamond detector.

  15. Methods for characterizing x-ray detectors for use at the National Ignition Facility.

    Science.gov (United States)

    Khan, S F; Benedetti, L R; Hargrove, D R; Glenn, S M; Simanovskaia, N; Holder, J P; Barrios, M A; Hahn, D; Nagel, S R; Bell, P M; Bradley, D K

    2012-10-01

    Gated and streaked x-ray detectors generally require corrections in order to counteract instrumental effects in the data. The method of correcting for gain variations in gated cameras fielded at National Ignition Facility (NIF) is described. Four techniques for characterizing the gated x-ray detectors are described. The current principal method of characterizing x-ray instruments is the production of controlled x-ray emission by laser-generated plasmas as a dedicated shot at the NIF. A recently commissioned pulsed x-ray source has the potential to replace the other characterization systems. This x-ray source features a pulsed power source consisting of a Marx generator, capacitor bank that is charged in series and discharged in parallel, producing up to 300 kV. The pulsed x-ray source initially suffered from a large jitter (∼60 ns), but the recent addition of a pulsed laser to trigger the spark gap has reduced the jitter to ∼5 ns. Initial results show that this tool is a promising alternative to the other flat fielding techniques.

  16. A cooled avalanche photodiode detector for X-ray magnetic diffraction experiments

    CERN Document Server

    Kishimoto, S; Ito, M

    2001-01-01

    A cooled avalanche photodiode (APD) detector was developed for X-ray magnetic diffraction experiments. A stack of four silicon APDs was cooled down to 243 K by a thermoelectric cooler. The energy widths of 0.89 and 1.55 keV (FWHM) were obtained for 8.05 keV X-rays at 1x10 sup 6 s sup - sup 1 and for 16.53 keV X-rays at 2x10 sup 6 s sup - sup 1 , respectively. Test measurements of X-ray magnetic diffraction were executed using a terbium single crystal and white synchrotron radiation. A peak width of (1 0 3) reflection (5.4 keV) was roughly three times wider than that with a high-purity germanium detector.

  17. Hard X-ray Detector Calibrations for the FOXSI Sounding Rocket

    Science.gov (United States)

    Lopez, A.; Glesener, L.; Buitrago Casas, J. C.; Han, R.; Ishikawa, S. N.; Christe, S.; Krucker, S.

    2015-12-01

    In the study of high-energy solar flares, detailed X-ray images and spectra of the Sun are required. The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket experiment is used to test direct-focusing X-ray telescopes and Double-sided Silicon Strip Detectors (DSSD) for solar flare study and to further understand coronal heating. The measurement of active region differential emission measures, flare temperatures, and possible quiet-Sun emission requires a precisely calibrated spectral response. This poster describes recent updates in the calibration of FOXSI's DSSDs based on new calibration tests that were performed after the second flight. The gain for each strip was recalculated using additional radioactive sources. Additionally, the varying strip sensitivity across the detectors was investigated and based on these measurements, the flight images were flatfielded. These improvements lead to more precise X-ray data for future FOXSI flights and show promise for these new technologies in imaging the Sun.

  18. X-ray position detector and implementation in a mirror pointing servo system

    Science.gov (United States)

    Rabedeau, Thomas A.; Van Campen, Douglas G.; Stefan, Peter M.

    2016-04-05

    An X-ray beam position and stability detector is provided having a first metal blade collinear with a second metal blade, where an edge of the first metal blade is opposite an edge of the second metal blade, where the first metal blade edge and the second metal blade edge are disposed along a centerline with respect to each other, where the metal blades are capable of photoelectron emission when exposed to an x-ray beam, a metal coating on the metal blades that is capable of enhancing the photoelectron emission, or suppressing energy-resonant contaminants, or enhancing the photoelectron emission and suppressing energy-resonant contaminants, a background shielding element having an electrode capable of suppressing photoelectron emission from spurious x-rays not contained in an x-ray beam of interest, and a photoelectron emission detector having an amplifier capable of detecting the photoelectron emission as a current signal.

  19. Note: application of a pixel-array area detector to simultaneous single crystal X-ray diffraction and X-ray absorption spectroscopy measurements.

    Science.gov (United States)

    Sun, Cheng-Jun; Zhang, Bangmin; Brewe, Dale L; Chen, Jing-Sheng; Chow, G M; Venkatesan, T; Heald, Steve M

    2014-04-01

    X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) are two main x-ray techniques in synchrotron radiation facilities. In this Note, we present an experimental setup capable of performing simultaneous XRD and XAS measurements by the application of a pixel-array area detector. For XRD, the momentum transfer in specular diffraction was measured by scanning the X-ray energy with fixed incoming and outgoing x-ray angles. By selecting a small fixed region of the detector to collect the XRD signal, the rest of the area was available for collecting the x-ray fluorescence for XAS measurements. The simultaneous measurement of XRD and X-ray absorption near edge structure for Pr0.67Sr0.33MnO3 film was demonstrated as a proof of principle for future time-resolved pump-probe measurements. A static sample makes it easy to maintain an accurate overlap of the X-ray spot and laser pump beam.

  20. On-orbit calibration of soft X-ray detector on Chang'E-2 satellite

    Science.gov (United States)

    Xiao, Hong; Peng, Wen-Xi; Wang, Huan-Yu; Cui, Xing-Zhu; Guo, Dong-Ya

    2015-10-01

    The X-ray spectrometer is one of the satellite payloads on the Chang'E-2 satellite. The soft X-ray detector is one of the devices on the X-ray spectrometer, designed to detect the major rock-forming elements within the 0.5-10 keV range on the lunar surface. In this paper, energy linearity and energy resolution calibration is done using a weak 55Fe source. Temperature and time effects are found not to give a large error. The total uncertainty of calibration is estimated to be within 5% after correction. Supported by National Science Foundation of Ministry of Education

  1. On-orbit calibration of soft X-ray detector on Chang'E-2 satellite

    CERN Document Server

    Xiao, Hong; Wang, Huanyu; Cui, Xingzhu; Guo, Dongya

    2015-01-01

    X-ray spectrometer is one of the satellite payloads on Chang'E-2 satellite. The soft X-ray detector is one of the device on X-ray spectrometer which is designed to detect the major rock-forming elements within 0.5-10keV range on lunar surface. In this paper, energy linearity and energy resolution calibration is done using a weak Fe55 source, while temperature and time effect is considered not take big error. The total uncertainty is estimated to be within 5% after correction.

  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. A setup for soft proton irradiation of X-ray detectors for future astronomical space missions

    OpenAIRE

    Sebastian DieboldKepler Center for Astro and Particle Physics - University of Tübingen; Philipp Azzarello(ISDC Data Centre for Astrophysics - University of Geneva); Ettore Del Monte(INAF/IASF Istituto di Astrofisica Spaziale e Fisica Cosmica - Rome); Marco Feroci(IAPS-INAF, Roma, Italy); Josef Jochum(Kepler Center for Astro and Particle Physics - University of Tübingen); Eckhard Kendziorra(Kepler Center for Astro and Particle Physics - University of Tübingen); Emanuele Perinati(Kepler Center for Astro and Particle Physics - University of Tübingen); Alexandre Rachevski(INFN Istituto Nazionale di Fisica Nucleare - Sezione di Trieste); Andrea Santangelo(Kepler Center for Astro and Particle Physics - University of Tübingen); Christoph Tenzer(Kepler Center for Astro and Particle Physics - University of Tübingen); Andrea Vacchi(INFN - Sezione di Trieste, Trieste, Italy); Gianluigi Zampa(INFN Istituto Nazionale di Fisica Nucleare - Sezione di Trieste); Nicola Zampa(INFN Istituto Nazionale di Fisica Nucleare - Sezione di Trieste)

    2013-01-01

    Protons that are trapped in the Earth's magnetic field are one of the main threats to astronomical X-ray observatories. Soft protons, in the range from tens of keV up to a few MeV, impinging on silicon X-ray detectors can lead to a significant degradation of the detector performance. Especially in low earth orbits an enhancement of the soft proton flux has been found. A setup to irradiate detectors with soft protons has been constructed at the Van-de-Graaff accelerator of th...

  5. Theoretical consideration of the energy resolution in planar HPGe detectors for low energy X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Samedov, Victor V. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31, Kashirskoye Shosse, 115409, Moscow, (Russian Federation)

    2015-07-01

    In this work, theoretical consideration of the processes in planar High Purity Ge (HPGe) detectors for low energy X-rays using the random stochastic processes formalism was carried out. Using the random stochastic processes formalism, the generating function of the processes of X-rays registration in a planar HPGe detector was derived. The power serial expansions of the detector amplitude and the variance in terms of the inverse bias voltage were derived. The coefficients of these expansions allow determining the Fano factor, electron mobility lifetime product, nonuniformity of the trap density, and other characteristics of the semiconductor material. (authors)

  6. Pixel sensitivity variations in a CdTe-Medipix2 detector using poly-energetic x-rays

    CERN Document Server

    Aamir, R; Greiffenberg, D; Lansley, S P; Butler, A P H; Zainon, R; Fauler, A; Fiederle, M

    2011-01-01

    We have a 1-mm-thick cadmium telluride (CdTe) sensor bump-bonded to a Medipix2 readout chip. This detector has been characterized using a poly-energetic x-ray beam. Open beam images (i.e. without an attenuating specimen between the x-ray source and the detector) have been acquired at room temperature using the MARS-CT system. Profiles of various rows and columns were analyzed for one hundred, 35-ms exposures taken with a bias voltage of -300 V (operating in electron collection mode). A region of increased sensitivity is observed around the edges of the detector. A reasonably periodic, repeatable variation in pixel sensitivity is observed. Some small regions with very low sensitivity and others with zero signals are also observed. Surrounding these regions are circular rings of pixels with higher counts. At higher flux (higher tube current in the x-ray source) there is evidence of saturation of the detector assembly. In this paper we present our understanding of the origin of these features and demonstrate the...

  7. Simulations of an X-Ray Detector Using Geant4

    Science.gov (United States)

    Ertley, Camden; McConnell, Mark; Bloser, Peter; Legere, Jason; Connor, Taylor; Ryan, James

    2009-10-01

    NASA's Black Hole Finder Probe mission has two proposed concepts. CASTER, one of the proposed concepts, is a scintillator based Coded Aperture Survey Telescope for Energetic Radiation. This paper focuses on the development of a simulation that accurately models the proposed CASTER detector. The current detector design consists of a Lanthanum Bromide (LaBr3) scintillator directly coupled to a multianode photomultiplier tube (MAPMT). This detector should be optimized to give the best energy and position resolution. The simulation is based on the Geant4 toolkit, a set of detector simulation tools developed at CERN. Geant4 was chosen because it accurately models radiation devices and detectors, while allowing the simulation of transport and boundary conditions of optical photons. The results of the simulation were compared with data taken in the lab with a ^57Co and an ^241Am source. Once validated, the simulations will be used to optimize the final detector design.

  8. High-energy X-ray diffraction using the Pixium 4700 flat-panel detector.

    Science.gov (United States)

    Daniels, J E; Drakopoulos, M

    2009-07-01

    The Pixium 4700 detector represents a significant step forward in detector technology for high-energy X-ray diffraction. The detector design is based on digital flat-panel technology, combining an amorphous Si panel with a CsI scintillator. The detector has a useful pixel array of 1910 x 2480 pixels with a pixel size of 154 microm x 154 microm, and thus it covers an effective area of 294 mm x 379 mm. Designed for medical imaging, the detector has good efficiency at high X-ray energies. Furthermore, it is capable of acquiring sequences of images at 7.5 frames per second in full image mode, and up to 60 frames per second in binned region of interest modes. Here, the basic properties of this detector applied to high-energy X-ray diffraction are presented. Quantitative comparisons with a widespread high-energy detector, the MAR345 image plate scanner, are shown. Other properties of the Pixium 4700 detector, including a narrow point-spread function and distortion-free image, allows for the acquisition of high-quality diffraction data at high X-ray energies. In addition, high frame rates and shutterless operation open new experimental possibilities. Also provided are the necessary data for the correction of images collected using the Pixium 4700 for diffraction purposes.

  9. Study on temperature coefficient of CdTe detector used for X-rays detection

    CERN Document Server

    Guo, Si-Ming; Zhang, Jian; Li, Xu-Fang; Liu, Cong-Zhan; Zhang, Shuai; Li, Cheng-Ze; Huo, Bin-Bin; Liao, Zhen-Yu

    2016-01-01

    The temperature of the working environment is a key factor in determining the properties of semiconductor detectors, and it affects the absolute accuracy and stability of the standard detector. In order to determine the temperature coefficient of CdTe detector used for X-rays detection, a precise temperature control system was designed. In this experiment, detectors and radiographic source were set inside the thermostat with temperature of 0-40 Celsius degree, so that the temperature can be regulated for the test of the temperature coefficient of CdTe detector. Studies had shown that, with the increase of the temperature, the energy resolution and detection efficiency of the CdTe detector would deteriorate, and under 10 Celsius degree the detectors have better performance with the 8 keV X-rays.

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

    Science.gov (United States)

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

    2012-12-01

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

  11. Two-dimensional imaging detectors for structural biology with X-ray lasers.

    Science.gov (United States)

    Denes, Peter

    2014-07-17

    Our ability to harness the advances in microelectronics over the past decade(s) for X-ray detection has resulted in significant improvements in the state of the art. Biology with X-ray free-electron lasers present daunting detector challenges: all of the photons arrive at the same time, and individual high peak power pulses must be read out shot-by-shot. Direct X-ray detection in silicon pixel detectors--monolithic or hybrid--are the standard for XFELs today. For structural biology, improvements are needed for today's 10-100 Hz XFELs, and further improvements are required for tomorrow's 10+ kHz XFELs. This article will discuss detector challenges, why they arise and ways to overcome them, along with the current state of the art. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  12. Development of an X-ray pixel detector with multi-port charge-coupled device for X-ray free-electron laser experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kameshima, Takashi [JASRI, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Ono, Shun; Kudo, Togo; Ozaki, Kyosuke; Kirihara, Yoichi; Kobayashi, Kazuo; Inubushi, Yuichi [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Yabashi, Makina; Hatsui, Takaki, E-mail: hatsui@spring8.or.jp [JASRI, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Horigome, Toshio [Institute for Molecular Science, Myodaiji, Okazaki 444-8585 (Japan); Holland, Andrew; Holland, Karen [XCam, Ltd, 2 Stone Circle Road, Round Spinney Industrial Estate, Northampton NN3 8RF (United Kingdom); Burt, David [e2v, 106 Waterhouse Lane, Chelmsford, Essex CM1 2QU (United Kingdom); Murao, Hajime [Meisei Electric Co. Ltd, Naganuma 2223, Isesaki, Gunma 372-8585 (Japan)

    2014-03-15

    This paper presents development of an X-ray pixel detector with a multi-port charge-coupled device (MPCCD) for X-ray Free-Electron laser experiments. The fabrication process of the CCD was selected based on the X-ray radiation hardness against the estimated annual dose of 1.6 × 10{sup 14} photon/mm{sup 2}. The sensor device was optimized by maximizing the full well capacity as high as 5 Me- within 50 μm square pixels while keeping the single photon detection capability for X-ray photons higher than 6 keV and a readout speed of 60 frames/s. The system development also included a detector system for the MPCCD sensor. This paper summarizes the performance, calibration methods, and operation status.

  13. Measurement of 238U muonic x-rays with a germanium detector setup

    Energy Technology Data Exchange (ETDEWEB)

    Esch, Ernst I [Los Alamos National Laboratory; Jason, Andrew [Los Alamos National Laboratory; Miyadera, Haruo [Los Alamos National Laboratory; Hoteling, Nathan J [Los Alamos National Laboratory; Heffner, Robert H [Los Alamos National Laboratory; Adelmann, Andreas [PAUL SCHERRER INSTITUT; Stocki, Trevor [HEALTH CANADA; Mitchell, Lee [NAVAL RESEARCH LAB

    2009-01-01

    In the field of nuclear non-proliferation muon interactions with materials are of great interest. This paper describes an experiment conducted at the Paul Scherrer Institut (PSI) in Switzerland where a muon beam is stopped in a uranium target. The muons produce characteristic muonic x-rays. Muons will penetrate shielding easily and the produced characteristic x-rays can be used for positive isotope identification. Furthermore, the x-rays for uranium isotopes lie in the energy range of 6-7 MeV, which allows them to have an almost optimal mean free path in heavy shielding such as lead or steel. A measurement was conducted at PSI to prove the feasibility of detecting muonic x-rays from a large sample of depleted uranium (several kilograms) with a germanium detector. In this paper, the experimental setup and analysis of the measurement itself is presented.

  14. Development of a fast multi-line x-ray CT detector for NDT

    Science.gov (United States)

    Hofmann, T.; Nachtrab, F.; Schlechter, T.; Neubauer, H.; Mühlbauer, J.; Schröpfer, S.; Ernst, J.; Firsching, M.; Schweiger, T.; Oberst, M.; Meyer, A.; Uhlmann, N.

    2015-04-01

    Typical X-ray detectors for non-destructive testing (NDT) are line detectors or area detectors, like e.g. flat panel detectors. Multi-line detectors are currently only available in medical Computed Tomography (CT) scanners. Compared to flat panel detectors, line and multi-line detectors can achieve much higher frame rates. This allows time-resolved 3D CT scans of an object under investigation. Also, an improved image quality can be achieved due to reduced scattered radiation from object and detector themselves. Another benefit of line and multi-line detectors is that very wide detectors can be assembled easily, while flat panel detectors are usually limited to an imaging field with a size of approx. 40 × 40 cm2 at maximum. The big disadvantage of line detectors is the limited number of object slices that can be scanned simultaneously. This leads to long scan times for large objects. Volume scans with a multi-line detector are much faster, but with almost similar image quality. Due to the promising properties of multi-line detectors their application outside of medical CT would also be very interesting for NDT. However, medical CT multi-line detectors are optimized for the scanning of human bodies. Many non-medical applications require higher spatial resolutions and/or higher X-ray energies. For those non-medical applications we are developing a fast multi-line X-ray detector.In the scope of this work, we present the current state of the development of the novel detector, which includes several outstanding properties like an adjustable curved design for variable focus-detector-distances, conserving nearly uniform perpendicular irradiation over the entire detector width. Basis of the detector is a specifically designed, radiation hard CMOS imaging sensor with a pixel pitch of 200 μ m. Each pixel has an automatic in-pixel gain adjustment, which allows for both: a very high sensitivity and a wide dynamic range. The final detector is planned to have 256 lines of

  15. Hard x-ray response of pixellated CdZnTe detectors

    Science.gov (United States)

    Abbene, L.; Del Sordo, S.; Caroli, E.; Gerardi, G.; Raso, G.; Caccia, S.; Bertuccio, G.

    2009-06-01

    In recent years, the development of cadmium zinc telluride (CdZnTe) detectors for x-ray and gamma ray spectrometry has grown rapidly. The good room temperature performance and the high spatial resolution of pixellated CdZnTe detectors make them very attractive in space-borne x-ray astronomy, mainly as focal plane detectors for the new generation of hard x-ray focusing telescopes. In this work, we investigated on the spectroscopic performance of two pixellated CdZnTe detectors coupled with a custom low noise and low power readout application specific integrated circuit (ASIC). The detectors (10×10×1 and 10×10×2 mm3 single crystals) have an anode layout based on an array of 256 pixels with a geometric pitch of 0.5 mm. The ASIC, fabricated in 0.8 μm BiCMOS technology, is equipped with eight independent channels (preamplifier and shaper) and characterized by low power consumption (0.5 mW/channel) and low noise (150-500 electrons rms). The spectroscopic results point out the good energy resolution of both detectors at room temperature [5.8% full width at half maximum (FWHM) at 59.5 keV for the 1 mm thick detector; 5.5% FWHM at 59.5 keV for the 2 mm thick detector) and low tailing in the measured spectra, confirming the single charge carrier sensing properties of the CdZnTe detectors equipped with a pixellated anode layout. Temperature measurements show optimum performance of the system (detector and electronics) at T =10 °C and performance degradation at lower temperatures. The detectors and the ASIC were developed by our collaboration as two small focal plane detector prototypes for hard x-ray multilayer telescopes operating in the 20-70 keV energy range.

  16. Photovoltaic x-ray detectors based on the GaAs epitaxial structures

    CERN Document Server

    Akhmadullin, R A; Dvoryankina, G G; Dikaev, Y M; Ermakov, M G; Ermakova, O N; Krikunov, A I; Kudryashov, A A; Petrov, A G; Telegin, A A

    2002-01-01

    The new photovoltaic detector of the X-ray radiation is proposed on the basis of the GaAs epitaxial structures, which operates with high efficiency of the charge carriers collection without shift voltage and at the room temperature. The structures are grown by the method of the gas-phase epitaxy on the n sup + -type highly-alloyed substrates. The range of sensitivity to the X-ray radiation is within the range of effective energies from 8 up to 120 keV. The detector maximum response in the current short circuit mode is determined

  17. Spectral x-ray computed tomography scanner using a cadmium telluride detector

    Science.gov (United States)

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

    2016-10-01

    To obtain four tomograms with four different photon energy ranges simultaneously, we have developed a quad-energy Xray photon counter with a cadmium telluride (CdTe) detector and four sets of comparators and frequency-voltage converters (FVCs). X-ray photons are detected using the CdTe detector, and the event pulses from a shaping amplifier are sent to four comparators simultaneously to regulate four threshold energies of 20, 35, 50 and 65 keV. Using this counter, the energy ranges are 20-100, 35-100, 50-100 and 65-100 keV; the maximum energy corresponds to the tube voltage. Xray photons in the four ranges are counted using the comparators, and the logical pulses from the comparators are input to the FVCs. The outputs from the four FVCs are input to a personal computer through an analog-digital converter (ADC) to carry out quad-energy imaging. To observe contrast variations with changes in the threshold energy, we performed spectral computed tomography utilizing the quad-energy photon counter at a tube voltage of 100 kV and a current of 8.0 μA. In the spectral CT, four tomograms were obtained simultaneously with four energy ranges. The image contrast varied with changes in the threshold energy, and the exposure time for tomography was 9.8 min.

  18. Fundamental x-ray interaction limits in diagnostic imaging detectors: spatial resolution.

    Science.gov (United States)

    Hajdok, G; Battista, J J; Cunningham, I A

    2008-07-01

    The practice of diagnostic x-ray imaging has been transformed with the emergence of digital detector technology. Although digital systems offer many practical advantages over conventional film-based systems, their spatial resolution performance can be a limitation. The authors present a Monte Carlo study to determine fundamental resolution limits caused by x-ray interactions in four converter materials: Amorphous silicon (a-Si), amorphous selenium, cesium iodide, and lead iodide. The "x-ray interaction" modulation transfer function (MTF) was determined for each material and compared in terms of the 50% MTF spatial frequency and Wagner's effective aperture for incident photon energies between 10 and 150 keV and various converter thicknesses. Several conclusions can be drawn from their Monte Carlo study. (i) In low-Z (a-Si) converters, reabsorption of Compton scatter x rays limits spatial resolution with a sharp MTF drop at very low spatial frequencies (x rays plays a dominant role, resulting in a mid-frequency (1-5 cycles/mm) MTF drop. (ii) Coherent scatter plays a minor role in the x-ray interaction MTF. (iii) The spread of energy due to secondary electron (e.g., photoelectrons) transport is significant only at very high spatial frequencies. (iv) Unlike the spread of optical light in phosphors, the spread of absorbed energy from x-ray interactions does not significantly degrade spatial resolution as converter thickness is increased. (v) The effective aperture results reported here represent fundamental spatial resolution limits of the materials tested and serve as target benchmarks for the design and development of future digital x-ray detectors.

  19. Optimizing detector geometry for trace element mapping by X-ray fluorescence.

    Science.gov (United States)

    Sun, Yue; Gleber, Sophie-Charlotte; Jacobsen, Chris; Kirz, Janos; Vogt, Stefan

    2015-05-01

    Trace metals play critical roles in a variety of systems, ranging from cells to photovoltaics. X-Ray Fluorescence (XRF) microscopy using X-ray excitation provides one of the highest sensitivities available for imaging the distribution of trace metals at sub-100 nm resolution. With the growing availability and increasing performance of synchrotron light source based instruments and X-ray nanofocusing optics, and with improvements in energy-dispersive XRF detectors, what are the factors that limit trace element detectability? To address this question, we describe an analytical model for the total signal incident on XRF detectors with various geometries, including the spectral response of energy dispersive detectors. This model agrees well with experimentally recorded X-ray fluorescence spectra, and involves much shorter calculation times than with Monte Carlo simulations. With such a model, one can estimate the signal when a trace element is illuminated with an X-ray beam, and when just the surrounding non-fluorescent material is illuminated. From this signal difference, a contrast parameter can be calculated and this can in turn be used to calculate the signal-to-noise ratio (S/N) for detecting a certain elemental concentration. We apply this model to the detection of trace amounts of zinc in biological materials, and to the detection of small quantities of arsenic in semiconductors. We conclude that increased detector collection solid angle is (nearly) always advantageous even when considering the scattered signal. However, given the choice between a smaller detector at 90° to the beam versus a larger detector at 180° (in a backscatter-like geometry), the 90° detector is better for trace element detection in thick samples, while the larger detector in 180° geometry is better suited to trace element detection in thin samples.

  20. Deep hard X-ray source counts from a fluctuation analysis of ASCA SIS images

    CERN Document Server

    Gendreau, K C; Fabian, A C

    1997-01-01

    An analysis of the spatial fluctuations in 15 deep ASCA SIS0 images has been conducted in order to probe the 2-10 keV X-ray source counts down to a flux limit 2E-14 erg/cm2/s. Special care has been taken in modelling the fluctuations in terms of the sensitivity maps of every one of the 16 regions (5.6 x 5.6 arcmin2 each) in which the SIS0 has been divided, by means of raytracing simulations with improved optical constants in the X-ray telescope. The very extended `side lobes' (extending up to a couple of degrees) exhibited by these sensitivity maps make our analysis sensitive to both faint on-axis sources and brighter off-axis ones, the former being dominant. The source counts in the range (2-12)E-14 erg/cm2/s are found to be close to a euclidean form which extrapolates well to previous results from higher fluxes and in reasonable agreement with some recent ASCA surveys. However, our results disagree with the deep survey counts by Georgantopoulos et al. (1997). The possibility that the source counts flatten t...

  1. Time-resolved and position-resolved X-ray spectrometry with a pixelated detector

    Energy Technology Data Exchange (ETDEWEB)

    Sievers, Peter

    2012-12-07

    The aim of the work presented here was to measure X-ray spectra with a pixelated detector. Due to effects in the sensor the spectrum cannot be measured directly and has to be calculated by a deconvolution of the measured data. In the scope of this work the deconvolution of the measured spectra could be enhanced considerably by - amongst other things - the introduction of the Bayesian deconvolution method. Those improvements opened the possibilities for further measurements. For the measurements the detectors of the Medipix family have been used. They are nowadays used for a wide range of applications and scientific research. Their main advantage is the very high position resolution gained by a pixel pitch of 55 μm and a high number of 65536 pixels. The Timepix detector has, in particular, two special possibilities of measurement: the ToA mode and the ToT mode. In ToA mode the arrival time of an impinging photon is measured and in ToT mode the amount of deposited charge is measured. The most common method of operation is counting the number of impinging photons that release a charge higher than a preset threshold in each pixel. As this released charge is proportional to the energy deposition of the impinging photon, one can perform energy-sensitive measurements. To perform the deconvolution of the measured energy distribution there is a need of an energy response matrix describing the detector response on radiation. For some detectors it is possible to obtain an analytic model of the response functions. Due to the high discrepancy between the impinging spectrum and the measured spectrum in case of detectors of the Medipix family, there is so far no analytic model. Thus, the detector response has to be simulated. As I could improve the precision of the measurement quite extensively, I also intended to tune the simulation with more accurate and appropriate models to gain the same level of accuracy. The results of measurement and simulation have then been compared and

  2. Superconducting single X-ray photon detector based on W0.8Si0.2

    CERN Document Server

    Zhang, X; Schilling, A

    2016-01-01

    We fabricated a superconducting single X-ray photon detector based on W0.8Si0.2, and we characterized its basic detection performance for keV-photons at different temperatures. The detector has a critical temperature of 4.97 K, and it is able to be operated up to 4.8 K, just below the critical temperature. The detector starts to react to X-ray photons at relatively low bias currents, less than 1% of Ic at T = 1.8 K, and it shows a saturated count rate dependence on bias current at all temperatures, indicating that the optimum internal quantum efficiency can always be reached. Dark counts are negligible up to the highest investigated bias currents (99% of Ic) and operating temperature (4.8 K). The latching effect affects the detector performance at all temperatures due to the fast recovery of the bias current; however, further modifications of the device geometry are expected to reduce the tendency for latching.

  3. Superconducting single X-ray photon detector based on W0.8Si0.2

    Directory of Open Access Journals (Sweden)

    Xiaofu Zhang

    2016-11-01

    Full Text Available We fabricated a superconducting single X-ray photon detector based on W0.8Si0.2, and we characterized its basic detection performance for keV-photons at different temperatures. The detector has a critical temperature of 4.97 K, and it is able to be operated up to 4.8 K, just below the critical temperature. The detector starts to react to X-ray photons at relatively low bias currents, less than 1% of Ic at T = 1.8 K, and it shows a saturated count rate dependence on bias current at all temperatures, indicating that the optimum internal quantum efficiency can always be reached. Dark counts are negligible up to the highest investigated bias currents (99% of Ic and operating temperature (4.8 K. The latching effect affects the detector performance at all temperatures due to the fast recovery of the bias current; however, further modifications of the device geometry are expected to reduce the tendency for latching.

  4. Bismuth Passivation Technique for High-Resolution X-Ray Detectors

    Science.gov (United States)

    Chervenak, James; Hess, Larry

    2013-01-01

    The Athena-plus team requires X-ray sensors with energy resolution of better than one part in 3,000 at 6 keV X-rays. While bismuth is an excellent material for high X-ray stopping power and low heat capacity (for large signal when an X-ray is stopped by the absorber), oxidation of the bismuth surface can lead to electron traps and other effects that degrade the energy resolution. Bismuth oxide reduction and nitride passivation techniques analogous to those used in indium passivation are being applied in a new technique. The technique will enable improved energy resolution and resistance to aging in bismuth-absorber-coupled X-ray sensors. Elemental bismuth is lithographically integrated into X-ray detector circuits. It encounters several steps where the Bi oxidizes. The technology discussed here will remove oxide from the surface of the Bi and replace it with nitridized surface. Removal of the native oxide and passivating to prevent the growth of the oxide will improve detector performance and insulate the detector against future degradation from oxide growth. Placing the Bi coated sensor in a vacuum system, a reduction chemistry in a plasma (nitrogen/hydrogen (N2/H2) + argon) is used to remove the oxide and promote nitridization of the cleaned Bi surface. Once passivated, the Bi will perform as a better X-ray thermalizer since energy will not be trapped in the bismuth oxides on the surface. A simple additional step, which can be added at various stages of the current fabrication process, can then be applied to encapsulate the Bi film. After plasma passivation, the Bi can be capped with a non-diffusive layer of metal or dielectric. A non-superconducting layer is required such as tungsten or tungsten nitride (WNx).

  5. The cluster charge identification in the GEM detector for fusion plasma imaging by soft X-ray diagnostics

    Science.gov (United States)

    Czarski, T.; Chernyshova, M.; Malinowski, K.; Pozniak, K. T.; Kasprowicz, G.; Kolasinski, P.; Krawczyk, R.; Wojenski, A.; Zabolotny, W.

    2016-11-01

    The measurement system based on gas electron multiplier detector is developed for soft X-ray diagnostics of tokamak plasmas. The multi-channel setup is designed for estimation of the energy and the position distribution of an X-ray source. The focal measuring issue is the charge cluster identification by its value and position estimation. The fast and accurate mode of the serial data acquisition is applied for the dynamic plasma diagnostics. The charge clusters are counted in the space determined by 2D position, charge value, and time intervals. Radiation source characteristics are presented by histograms for a selected range of position, time intervals, and cluster charge values corresponding to the energy spectra.

  6. The cluster charge identification in the GEM detector for fusion plasma imaging by soft X-ray diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Czarski, T., E-mail: tomasz.czarski@ifpilm.pl; Chernyshova, M.; Malinowski, K. [Institute of Plasma Physics and Laser Microfusion, Hery 23, 01-497 Warsaw (Poland); Pozniak, K. T.; Kasprowicz, G.; Kolasinski, P.; Krawczyk, R.; Wojenski, A.; Zabolotny, W. [Warsaw University of Technology, Nowowiejska 15/19, 00-665 Warsaw (Poland)

    2016-11-15

    The measurement system based on gas electron multiplier detector is developed for soft X-ray diagnostics of tokamak plasmas. The multi-channel setup is designed for estimation of the energy and the position distribution of an X-ray source. The focal measuring issue is the charge cluster identification by its value and position estimation. The fast and accurate mode of the serial data acquisition is applied for the dynamic plasma diagnostics. The charge clusters are counted in the space determined by 2D position, charge value, and time intervals. Radiation source characteristics are presented by histograms for a selected range of position, time intervals, and cluster charge values corresponding to the energy spectra.

  7. On the use of CCD area detectors for high-resolution specular X-ray reflectivity.

    Science.gov (United States)

    Fenter, P; Catalano, J G; Park, C; Zhang, Z

    2006-07-01

    The use and application of charge coupled device (CCD) area detectors for high-resolution specular X-ray reflectivity is discussed. Direct comparison of high-resolution specular X-ray reflectivity data measured with CCD area detectors and traditional X-ray scintillator ('point') detectors demonstrates that the use of CCD detectors leads to a substantial (approximately 30-fold) reduction in data acquisition rates because of the elimination of the need to scan the sample to distinguish signal from background. The angular resolution with a CCD detector is also improved by a factor of approximately 3. The ability to probe the large dynamic range inherent to high-resolution X-ray reflectivity data in the specular reflection geometry was demonstrated with measurements of the orthoclase (001)- and alpha-Al2O3 (012)-water interfaces, with measured reflectivity signals varying by a factor of approximately 10(6) without the use of any beam attenuators. Statistical errors in the reflectivity signal are also derived and directly compared with the repeatability of the measurements.

  8. Towards hybrid pixel detectors for energy-dispersive or soft X-ray photon science.

    Science.gov (United States)

    Jungmann-Smith, J H; Bergamaschi, A; Brückner, M; Cartier, S; Dinapoli, R; Greiffenberg, D; Huthwelker, T; Maliakal, D; Mayilyan, D; Medjoubi, K; Mezza, D; Mozzanica, A; Ramilli, M; Ruder, Ch; Schädler, L; Schmitt, B; Shi, X; Tinti, G

    2016-03-01

    JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional hybrid pixel detector for photon science applications at free-electron lasers and synchrotron light sources. The JUNGFRAU 0.4 prototype presented here is specifically geared towards low-noise performance and hence soft X-ray detection. The design, geometry and readout architecture of JUNGFRAU 0.4 correspond to those of other JUNGFRAU pixel detectors, which are charge-integrating detectors with 75 µm × 75 µm pixels. Main characteristics of JUNGFRAU 0.4 are its fixed gain and r.m.s. noise of as low as 27 e(-) electronic noise charge (X-ray irradiation from an X-ray tube and a synchrotron light source are successfully demonstrated with an r.m.s. energy resolution of 20% (no mask) and 14% (with the mask) at 1.2 keV and of 5% at 13.3 keV. The performance evaluation of the JUNGFRAU 0.4 prototype suggests that this detection system could be the starting point for a future detector development effort for either applications in the soft X-ray energy regime or for an energy-dispersive detection system.

  9. Large area high-resolution CCD-based X-ray detector for macromolecular crystallography

    CERN Document Server

    Pokric, M; Jorden, A R; Cox, M P; Marshall, A; Long, P G; Moon, K; Jerram, P A; Pool, P; Nave, C; Derbyshire, G E; Helliwell, J R

    2002-01-01

    An X-ray detector system for macromolecular crystallography based on a large area charge-coupled device (CCD) sensor has been developed as part of a large research and development programme for advanced X-ray sensor technology, funded by industry and the Particle Physics and Astronomy Research Council (PPARC) in the UK. The prototype detector consists of two large area three-sides buttable charge-coupled devices (CCD 46-62 EEV), where the single CCD area is 55.3 mmx41.5 mm. Overall detector imaging area is easily extendable to 85 mmx110 mm. The detector consists of an optically coupled X-ray sensitive phosphor, skewed fibre-optic studs and CCDs. The crystallographic measurement requirements at synchrotron sources are met through a high spatial resolution (2048x1536 pixel array), high dynamic range (approx 10 sup 5), a fast readout (approx 1 s), low noise (<10e sup -) and much reduced parallax error. Additionally, the prototype detector system has been optimised by increasing its efficiency at low X-ray ene...

  10. An InGrid based Low Energy X-ray Detector

    CERN Document Server

    Krieger, Christoph; Kaminski, Jochen; Lupberger, Michael; Vafeiadis, Theodoros

    2014-01-01

    An X-ray detector based on the combination of an integrated Micromegas stage with a pixel chip has been built in order to be installed at the CERN Axion Solar Telescope. Due to its high granularity and spatial resolution this detector allows for a topological background suppression along with a detection threshold below $1\\,\\text{keV}$. Tests at the CAST Detector Lab show the detector's ability to detect X-ray photons down to an energy as low as $277\\,\\text{eV}$. The first background data taken after the installation at the CAST experiment underline the detector's performance with an average background rate of $5\\times10^{-5}\\,/\\text{keV}/\\text{cm}^2/\\text{s}$ between 2 and $10\\,\\text{keV}$ when using a lead shielding.

  11. Investigation of GEM-Micromegas Detector on X-ray Beam of Synchrotron Radiation

    CERN Document Server

    Zhang, YuLian; Hu, BiTao; Fan, ShengNan; Wang, Bo; Liu, Mei; Zhang, Jian; Liu, RongGuang; Chang, GuangCai; Liu, Peng; Ouyang, Qun; Chen, YuanBo; Yi, FuTing

    2013-01-01

    To solve the discharge of the standard Bulk Micromegas and GEM detector, the GEM-Micromegas detector was developed in Institute of High Energy Physics. Taking into account the advantages of the two detectors, one GEM foil was set as a preamplifier on the mesh of Micromegas in the structure and the GEM preamplification decreased the working voltage of Micromegas to reduce the effect of the discharge significantly. In the paper, the performance of detector in X-ray beam was studied at 1W2B laboratory of Beijing Synchrotron Radiation Facility. Finally, the result of the energy resolution under various X-ray energies was given in different working gases. It indicated that the GEM-Micromegas detector had the energy response capability in all the energy range and it could work better than the standard Bulk-Micromegas.

  12. A new solid-conversion gas detector for high energy X-ray industrial computed tomography

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ri-feng; CHEN Wei-min; DUAN Xiao-jiao

    2011-01-01

    A new type of solid-conversion gas detector is investigated for high energy X-ray industrial computed tomography(H ECT).The conversion efficiency is calculated by using the EGSnrc Monte Carlo code on the Linux platform to simulate the transport process of photons and electrons in the detector.The simulation results show that the conversion efficiency could be more than 65%,if the X-ray beam width is less than about 0.2 mm,and a tungsten slab with 0.2 mum thickness and 30 mm length is employed as a radiation conversion medium.Meanwhile the results indicate that this new detector has higher conversion efficiency as well as less volume.Theoretically this new kind of detector could take place of the traditional scintillation detector for HECT.

  13. X-ray micro-beam characterization of a small pixel spectroscopic CdTe detector

    Science.gov (United States)

    Veale, M. C.; Bell, S. J.; Seller, P.; Wilson, M. D.; Kachkanov, V.

    2012-07-01

    A small pixel, spectroscopic, CdTe detector has been developed at the Rutherford Appleton Laboratory (RAL) for X-ray imaging applications. The detector consists of 80 × 80 pixels on a 250 μm pitch with 50 μm inter-pixel spacing. Measurements with an 241Am γ-source demonstrated that 96% of all pixels have a FWHM of better than 1 keV while the majority of the remaining pixels have FWHM of less than 4 keV. Using the Diamond Light Source synchrotron, a 10 μm collimated beam of monochromatic 20 keV X-rays has been used to map the spatial variation in the detector response and the effects of charge sharing corrections on detector efficiency and resolution. The mapping measurements revealed the presence of inclusions in the detector and quantified their effect on the spectroscopic resolution of pixels.

  14. An X-ray scanner prototype based on a novel hybrid gaseous detector

    CERN Document Server

    Iacobaeus, C; Lund-Jensen, B; Peskov, Vladimir

    2007-01-01

    We have developed a prototype of a new type of hybrid X-ray detector. It contains a thin wall (few μm) edge- illuminated lead glass capillary plate (acting as a converter of X-rays photons to primary electrons) combined with a microgap parallel-plate avalanche chamber operating in various gas mixtures at 1 atm. The operation of these converters was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident angles varying from 0° to 90°. The detection efficiency, depending on the geometry, photon's energy, incident angle and the mode of operation, was between a few and 40%. The position resolution achieved was 50 μm in digital form and was practically independent of the photon's energy or gas mixture. The developed detector may open new possibilities for medical imaging, for example in mammography, portal imaging, radiography (including security devices), crystallography and many other applications.

  15. Fundamental x-ray interaction limits in diagnostic imaging detectors: frequency-dependent Swank noise.

    Science.gov (United States)

    Hajdok, G; Battista, J J; Cunningham, I A

    2008-07-01

    A frequency-dependent x-ray Swank factor based on the "x-ray interaction" modulation transfer function and normalized noise power spectrum is determined from a Monte Carlo analysis. This factor was calculated in four converter materials: amorphous silicon (a-Si), amorphous selenium (a-Se), cesium iodide (CsI), and lead iodide (PbI2) for incident photon energies between 10 and 150 keV and various converter thicknesses. When scaled by the quantum efficiency, the x-ray Swank factor describes the best possible detective quantum efficiency (DQE) a detector can have. As such, this x-ray interaction DQE provides a target performance benchmark. It is expressed as a function of (Fourier-based) spatial frequency and takes into consideration signal and noise correlations introduced by reabsorption of Compton scatter and photoelectric characteristic emissions. It is shown that the x-ray Swank factor is largely insensitive to converter thickness for quantum efficiency values greater than 0.5. Thus, while most of the tabulated values correspond to thick converters with a quantum efficiency of 0.99, they are appropriate to use for many detectors in current use. A simple expression for the x-ray interaction DQE of digital detectors (including noise aliasing) is derived in terms of the quantum efficiency, x-ray Swank factor, detector element size, and fill factor. Good agreement is shown with DQE curves published by other investigators for each converter material, and the conditions required to achieve this ideal performance are discussed. For high-resolution imaging applications, the x-ray Swank factor indicates: (i) a-Si should only be used at low-energy (e.g., mammography); (ii) a-Se has the most promise for any application below 100 keV; and (iii) while quantum efficiency may be increased at energies just above the K edge in CsI and PbI2, this benefit is offset by a substantial drop in the x-ray Swank factor, particularly at high spatial frequencies.

  16. Analysis of the charge collection process in solid state X-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kimmel, Nils

    2009-02-12

    Physics with X-rays spans from observing large scales in X-ray astronomy down to small scales in material structure analyses with synchrotron radiation. Both fields of research require imaging detectors featuring spectroscopic resolution for X-rays in an energy range of 0.1 keV to 20.0 keV. Originally driven by the need for an imaging spectrometer on ESA's X-ray astronomy satellite mission XMM-Newton, X-ray pnCCDs were developed at the semiconductor laboratory of the Max-Planck-Institute. The pnCCD is a pixel array detector made of silicon. It is sensitive over a wide band from near infrared- over optical- and UV-radiation up to X-rays. This thesis describes the dynamics of signal electrons from the moment after their generation until their collection in the potential minima of the pixel structure. Experimentally, a pinhole array was used to scan the pnCCD surface with high spatial resolution. Numerical simulations were used as a tool for the modeling of the electrical conditions inside the pnCCD. The results predicted by the simulations were compared with the measurements. Both, experiment and simulation, helped to establish a model for the signal charge dynamics in the energy range from 0.7 keV to 5.5 keV. More generally, the presented work has enhanced the understanding of the detector system on the basis of a physical model. The developed experimental and theoretical methods can be applied to any type of array detector which is based on the full depletion of a semiconductor substrate material. (orig.)

  17. Development of edgeless TSV X-ray detectors

    Science.gov (United States)

    Sarajlić, M.; Zhang, J.; Pennicard, D.; Smoljanin, S.; Fritzsch, T.; Wilke, M.; Zoschke, K.; Graafsma, H.

    2016-02-01

    We report about the activity and progress on the development of TSV edgeless detectors at DESY. One part of the development is Through Silicon Via (TSV) technology for the Medipix3RX readout chip (ROC). TSV technology is a concept of connecting readout chips to readout electronics. Instead of wire-bonding which introduces a large dead area, TSV enables connection through the ROC itself. By replacing wire-bonding with TSV, the dead space between detector modules will be reduced from around 7 mm to only 1.6 mm. The thickness of the wafer will be 200 μ m, with a via diameter of 60 μ m. Inside of the via, a 5 μ m thick copper layer will be used as a conducting layer. On the back side of the chip a Redistribution Layer (RDL) will be deposited. For the RDL structure, 5 μ m thick copper with 40 μ m wide conductive lines will be used. Bump bonding of the sensor plus ROC assembly to ceramic readout board will be optimized in terms of material and bonding temperature. The second part of the project is the development of the edgeless sensor units using active edge sensor technology. Active edge sensors have been simulated with Synopsys TCAD for different polarities including p-on-n, p-on-p, n-on-p and n-on-n with p-spray or p-stop for different thicknesses from 150 μ m to 500 μ m. Results show that the bending of the electric field close to the active edge is leading to image distortion on the sensor edge. In addition, the current design of active-edge sensors shows very poor radiation hardness. We are currently working on the development of a radiation hard active-edge sensor with optimized imaging quality. The final goal of this development is to make Large Area Medipix Detector (LAMBDA) with TSV edgeless units.

  18. High-speed X-ray imaging pixel array detector for synchrotron bunch isolation

    Energy Technology Data Exchange (ETDEWEB)

    Philipp, Hugh T., E-mail: htp2@cornell.edu; Tate, Mark W.; Purohit, Prafull; Shanks, Katherine S.; Weiss, Joel T. [Cornell University, Ithaca, NY 14853 (United States); Gruner, Sol M. [Cornell University, Ithaca, NY 14853 (United States); Cornell University, Ithaca, NY 14853 (United States)

    2016-01-28

    A high-speed pixel array detector for time-resolved X-ray imaging at synchrotrons has been developed. The ability to isolate single synchrotron bunches makes it ideal for time-resolved dynamical studies. A wide-dynamic-range imaging X-ray detector designed for recording successive frames at rates up to 10 MHz is described. X-ray imaging with frame rates of up to 6.5 MHz have been experimentally verified. The pixel design allows for up to 8–12 frames to be stored internally at high speed before readout, which occurs at a 1 kHz frame rate. An additional mode of operation allows the integration capacitors to be re-addressed repeatedly before readout which can enhance the signal-to-noise ratio of cyclical processes. This detector, along with modern storage ring sources which provide short (10–100 ps) and intense X-ray pulses at megahertz rates, opens new avenues for the study of rapid structural changes in materials. The detector consists of hybridized modules, each of which is comprised of a 500 µm-thick silicon X-ray sensor solder bump-bonded, pixel by pixel, to an application-specific integrated circuit. The format of each module is 128 × 128 pixels with a pixel pitch of 150 µm. In the prototype detector described here, the three-side buttable modules are tiled in a 3 × 2 array with a full format of 256 × 384 pixels. The characteristics, operation, testing and application of the detector are detailed.

  19. X-ray light valve (XLV): a novel detectors' technology for digital mammography

    Science.gov (United States)

    Marcovici, Sorin; Sukhovatkin, Vlad; Oakham, Peter

    2014-03-01

    A novel method, based on X-ray Light Valve (XLV) technology, is proposed for making good image quality yet inexpensive flat panel detectors for digital mammography. The digital mammography markets, particularly in the developing countries, demand quality machines at substantially lower prices than the ones available today. Continuous pressure is applied on x-ray detectors' manufacturers to reduce the flat panel detectors' prices. XLV presents a unique opportunity to achieve the needed price - performance characteristics for direct conversion, x-ray detectors. The XLV based detectors combine the proven, superior, spatial resolution of a-Se with the simplicity and low cost of liquid crystals and optical scanning. The x-ray quanta absorbed by a 200 μm a-Se produce electron - hole pairs that move under an electric field to the top and bottom of a-Se layer. This 2D charge distribution creates at the interface with the liquid crystals a continuous (analog) charge image corresponding to the impinging radiation's information. Under the influence of local electrical charges next to them, the liquid crystals twist proportionally to the charges and vary their light reflectivity. A scanning light source illuminates the liquid crystals while an associated, pixilated photo-detector, having a 42 μm pixel size, captures the light reflected by the liquid crystals and converts it in16 bit words that are transmitted to the machine for image processing and display. The paper will describe a novel XLV, 25 cm x 30 cm, flat panel detector structure and its underlying physics as well as its preliminary performance measured on several engineering prototypes. In particular, the paper will present the results of measuring XLV detectors' DQE, MTF, dynamic range, low contrast resolution and dynamic behavior. Finally, the paper will introduce the new, low cost, XLV detector based, digital mammography machine under development at XLV Diagnostics Inc.

  20. Superconducting X-ray detectors based on Nb absorbers and Nb/Al tunnel junctions

    NARCIS (Netherlands)

    Hamster, Arnout Willem

    1999-01-01

    This thesis describes the research and development of STJs based on Nb/Al technology for application as X-ray detectors in astrophysics conducted by the Low Temperature division of the University of Twente in collaboration with the Stichting Ruimteonderzoek Nederland (SRON). Three topics have been i

  1. Design and Implementation of High-speed X-ray Nondestructive Detector

    Institute of Scientific and Technical Information of China (English)

    MENG Xian-yi; MIAO Chang-yun; WANG Wei; SUN Xue

    2008-01-01

    A high-speed X-ray nondestructive detector is designed in this paper. The principle of X-ray nondestructive detection is analyzed, and a general system scheme of the high-speed X-ray nondestructive detector is proposed. The Virtex-4 series Fx12 FPGA chip is used to design its hardware circuit, the PowerPC405 embedded system is developed, the high-speed image processing algorithm is applied to compile its processing software, and TCP/IP protocol is employed to compile the correspondence software, to realize high-speed X-ray signal gathering, processing and transmission. The experimental result indicated that the detector can be applied to the long-distance and on-line nondestructive detection of product line with Steel Wire Ropes in correlative industry field, such as mines, ports and wharfs. The running rate of the conveyer belt could achieve 6m/s when the survey width of the detector is 1.6 m.

  2. Edgeless silicon sensors for Medipix-based large-area X-ray imaging detectors

    NARCIS (Netherlands)

    Bosma, M.J.; Visser, J.; Evrard, O.; de Moor, P.; de Munck, K.; Sabuncuoglu Tezcan, D.; Koffeman, E.N.

    2011-01-01

    Some X-ray imaging applications demand sensitive areas exceeding the active area of a single sensor. This requires a seamless tessellation of multiple detector modules with edgeless sensors. Our research is aimed at minimising the insensitive periphery that isolates the active area from the edge. Re

  3. A liquid-helium cooled large-area silicon PIN photodiode x-ray detector

    CERN Document Server

    Inoue, Y; Hara, H; Minowa, M; Shimokoshi, F; Inoue, Yoshizumi; Moriyama, Shigetaka; Hara, Hideyuki; Minowa, Makoto; Shimokoshi, Fumio

    1995-01-01

    An x-ray detector using a liquid-helium cooled large-area silicon PIN photodiode has been developed along with a tailor-made charge sensitive preamplifier whose first-stage JFET has been cooled. The operating temperature of the JFET has been varied separately and optimized. The x- and \\gamma-ray energy spectra for an \

  4. Recent developments in a CdTe-based x-ray detector for digital radiography

    Science.gov (United States)

    Glasser, Francis; Martin, Jean-Luc; Thevenin, Bernard; Schermesser, Patrick; Pantigny, Philippe; Laurent, Jean Yves; Rambaud, Philippe; Pitault, Bernard; Paltrier, Sylvain

    1997-05-01

    The performance of a new CdTe based x-ray detector devoted to digital radiography are presented. The detectors consist of a 6 cm2 CdTe 2D-array connected to CMOS readout circuit by indium bumps. The final image has 400 X 600 pixels with a 50 micron pitch. This solid-state detector presents the advantages of direct conversion, i.e. high stopping power with high spatial resolution and a significantly higher signal than commercially available scintillator/photodetector systems. The experimental results show excellent linearity, spatial resolution and detective quantum efficiency. The MTF was measured by the angled-slit method: 20 to 30 percent at 10 1p/mm depending on the incident x-ray energy. The measured DQE is about 0.8 at 40 KeV and 100 (mu) Gray dose. Our simulation shows that these experimental results do not reach the theoretical limit. Further improvements are in progress. The first industrial application will be dental radiography due to the small size and the excellent performances. We also tested the detector with x-rays form 20 KeV to 1.25 MeV. Of course the CdTe thickness should then be adapted to the incident x-ray energy.

  5. Superconducting X-ray detectors based on Nb absorbers and Nb/Al tunnel junctions

    NARCIS (Netherlands)

    Hamster, A.W.

    1999-01-01

    This thesis describes the research and development of STJs based on Nb/Al technology for application as X-ray detectors in astrophysics conducted by the Low Temperature division of the University of Twente in collaboration with the Stichting Ruimteonderzoek Nederland (SRON). Three topics have been

  6. Development of CZT detectors for x-ray and gamma-ray astronomy

    Science.gov (United States)

    Lee, Kuen; Martin, J. W.; Garson, A., III; Guo, Q.; Matteson, J.; Groza, M.; Beilicke, M.; Burger, A.; de Geronimo, G.; Krawczynski, H.

    2011-09-01

    Cadmium Zinc Telluride (CZT) is the detector material of choice for the detection of X-rays in the 10 keV-1MeV energy band with excellent spatial and energy resolutions and without cryogenic cooling. In this contribution, we report on recent results of the CZT detector development program and several astrophysical experiments which make use of CZT detectors. In the first part of the paper, we discuss the performance of pixel and cross-strip CZT detectors read out with an ASIC developed at the Brookhaven National Laboratory. Our pixel detectors achieve some of the best energy resolutions reported in the literature. Cross-strip detectors are found to give an inferior performance and we investigate the reason for this performance difference. We also present results from a precision measurement of the effect of a steering grid on multi-pixel events obtained with a 200 micrometer collimator. In the second part of the paper, we describe the design and performance of the hard X-ray polarimeter X-Calibur. The polarimeter uses a 14 cm long scintillator scatterer, surrounded by an assembly of 32 2-5 mm thick CZT detectors. We discuss the sensitivity of the polarimeter to measure the linear polarization of 10 keV-80 keV X-rays on short and long balloon flights and results from testing the polarimeter in the laboratory.

  7. Sensitive X-ray detectors made of methylammonium lead tribromide perovskite single crystals

    Science.gov (United States)

    Wei, Haotong; Fang, Yanjun; Mulligan, Padhraic; Chuirazzi, William; Fang, Hong-Hua; Wang, Congcong; Ecker, Benjamin R.; Gao, Yongli; Loi, Maria Antonietta; Cao, Lei; Huang, Jinsong

    2016-05-01

    The large mobilities and carrier lifetimes of hybrid perovskite single crystals and the high atomic numbers of Pb, I and Br make them ideal for X-ray and gamma-ray detection. Here, we report a sensitive X-ray detector made of methylammonium lead bromide perovskite single crystals. A record-high mobility-lifetime product of 1.2 × 10-2 cm2 V-1 and an extremely small surface charge recombination velocity of 64 cm s-1 are realized by reducing the bulk defects and passivating surface traps. Single-crystal devices with a thickness of 2-3 mm show 16.4% detection efficiency at near zero bias under irradiation with continuum X-ray energy up to 50 keV. The lowest detectable X-ray dose rate is 0.5 μGyair s-1 with a sensitivity of 80 μC Gy-1air cm-2, which is four times higher than the sensitivity achieved with α-Se X-ray detectors. This allows the radiation dose applied to a human body to be reduced for many medical and security check applications.

  8. A High Position Resolution X-ray Detector: an Edge on Illuminated Capillary Plate Combined with a Gas Amplification Structure

    CERN Document Server

    Iacobaeus, C; Lund-Jensen, B; Ostling, J; Pavlopoulos, P; Peskov, Vladimir; Tokanai, F

    2006-01-01

    We have developed and successfully tested a prototype of a new type of high position resolution hybrid X-ray detector. It contains a thin wall lead glass capillary plate converter of X-rays combined with a microgap parallel-plate avalanche chamber filled with gas at 1 atm. The operation of these converters was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident angles varying from 0-90 degree. The detection efficiency, depending on the geometry, photon energy, incident angle and the mode of operation, was between 5-30 percent in a single step mode and up to 50 percent in a multi-layered combination. Depending on the capillary geometry, the position resolution achieved was between 0.050-0.250 mm in digital form and was practically independent of the photon energy or gas mixture. The usual lead glass capillary plates operated without noticeable charging up effects at counting rates of 50 Hz/mm2, and hydrogen treated capillaries up to 10E5 Hz/mm2. The developed detector may open new possibil...

  9. Yoneda-XAFS with Area X-Ray Detectors

    Science.gov (United States)

    Gasse, J.-C.; Lützenkirchen-Hecht, D.; Wagner, R.; Frahm, R.

    2016-05-01

    ReflXAFS is a well-known, surface sensitive method to investigate the structure of e.g. thin films. By a proper choice of incident and exit angles the Yoneda-peak, a distinct intensity maximum in the diffuse scattering, becomes visible. For multilayered samples, several Yoneda-peaks related to surface and interface regions may be observed. It is possible to utilize these peaks to measure the fine structure of an element inside the related surface and interface regions of a multi-layered sample. We will show that the use of 2D-area detectors allow the simultaneous measurement of the entire scattering pattern for each energy in an EXAFS spectrum, providing access to detailed in-situ structure information of the surface and interface regions in multilayered samples.

  10. Use of mercuric iodide X-ray detectors with alpha backscattering spectrometers for space applications

    Science.gov (United States)

    Iwanczyk, J. S.; Wang, Y. J.; Dorri, N.; Dabrowski, A. J.; Economou, T. E.

    1991-01-01

    The authors present X-ray fluorescence (XRF) spectra of different extraterrestrial samples taken with a mercuric iodide (HgI2) spectrometer inserted into an alpha backscattering instrument identical to that used in the Soviet Phobos mission. The results obtained with the HgI2 ambient temperature detector are compared with those obtained using an Si(Li) cryogenically cooled detector. Efforts to design an optimized instrument for space application are also described. The results presented indicate that the energy resolution and sensitivity of HgI2 detectors are adequate to meet the performance needs of a number of proposed space applications, particularly those in which cooled silicon X-ray detectors are impractical or even not usable, such as for the target science programs on geoscience opportunities for lunar surface, Mars surface, and other comet and planetary missions being planned by NASA and ESA.

  11. Bio-medical X-ray imaging with spectroscopic pixel detectors

    CERN Document Server

    Butler, A P H; Tipples, R; Cook, N; Watts, R; Meyer, J; Bell, A J; Melzer, T R; Butler, P H

    2008-01-01

    The aim of this study is to review the clinical potential of spectroscopic X-ray detectors and to undertake a feasibility study using a novel detector in a clinical hospital setting. Detectors currently in development, such as Medipix-3, will have multiple energy thresholds allowing for routine use of spectroscopic bio-medical imaging. We have coined the term MARS (Medipix All Resolution System) for bio-medical images that provide spatial, temporal, and energy information. The full clinical significance of spectroscopic X-ray imaging is difficult to predict but insights can be gained by examining both image reconstruction artifacts and the current uses of dual-energy techniques. This paper reviews the known uses of energy information in vascular imaging and mammography, clinically important fields. It then presents initial results from using Medipix-2, to image human tissues within a clinical radiology department. Detectors currently in development, such as Medipix-3, will have multiple energy thresholds allo...

  12. Pixel readout ASIC for an APD based 2D X-ray hybrid pixel detector with sub-nanosecond resolution

    Energy Technology Data Exchange (ETDEWEB)

    Thil, Ch., E-mail: christophe.thil@ziti.uni-heidelberg.d [Heidelberg University, Institute of Computer Engineering, B6, 26, 68161 Mannheim (Germany); Baron, A.Q.R. [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Fajardo, P. [ESRF, Polygone Scientifique Louis Neel, 6, rue Jules Horowitz, 38000 Grenoble (France); Fischer, P. [Heidelberg University, Institute of Computer Engineering, B6, 26, 68161 Mannheim (Germany); Graafsma, H. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Rueffer, R. [ESRF, Polygone Scientifique Louis Neel, 6, rue Jules Horowitz, 38000 Grenoble (France)

    2011-02-01

    The fast response and the short recovery time of avalanche photodiodes (APDs) in linear mode make those devices ideal for direct X-ray detection in applications requiring high time resolution or counting rate. In order to provide position sensitivity, the XNAP project aims at creating a hybrid pixel detector with nanosecond time resolution based on a monolithic APD sensor array with 32 x32 pixels covering about 1 cm{sup 2} active area. The readout is implemented in a pixelated front-end ASIC suited for the readout of such arrays, matched to pixels of 280{mu}mx280{mu}m size. Every single channel features a fast transimpedance amplifier, a discriminator with locally adjustable threshold and two counters with high dynamic range and counting speed able to accumulate X-ray hits with no readout dead time. Additionally, the detector can be operated in list mode by time-stamping every single event with sub-nanosecond resolution. In a first phase of the project, a 4x4 pixel test module is built to validate the conceptual design of the detector. The XNAP project is briefly presented and the performance of the readout ASIC is discussed.

  13. High-resolution imaging X-ray detector. [using microchannel plates and electronic readout for spaceborne telescope

    Science.gov (United States)

    Kellogg, E.; Henry, P.; Murray, S.; Van Speybroeck, L.; Bjorkholm, P.

    1976-01-01

    The paper describes an X-ray detector using microchannel plates as a photocathode surface and imaging photoelectron multiplier, and a crossed wire grid as a two-dimensional position-sensitive detector. The position resolution is 10 microns. The crossed wire grid consists of 100-micron-diam wires on 200-micron centers. Position sensing is accomplished by electronic interpolation to 1/20 of the wire spacing. The quantum efficiency of the microchannel plates varies from 29% at 0.28 keV to 5% at 3 keV. This detector will provide second-of-arc X-ray imaging in the focal plane of the 342.9-cm focal length grazing-incidence telescope being prepared for the HEAO-B observatory. By addition of suitable photocathodes, it can be used for single-photon imaging light detection in the UV, visible, and near-IR-ranges. In all cases, it gives a very low dark counting rate, allows timing of individual events to 1 microsec or less, and can handle counting rates up to 10,000 per sec.

  14. High density processing electronics for superconducting tunnel junction x-ray detector arrays

    Energy Technology Data Exchange (ETDEWEB)

    Warburton, W.K., E-mail: bill@xia.com [XIA LLC, 31057 Genstar Road, Hayward, CA 94544 (United States); Harris, J.T. [XIA LLC, 31057 Genstar Road, Hayward, CA 94544 (United States); Friedrich, S. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States)

    2015-06-01

    Superconducting tunnel junctions (STJs) are excellent soft x-ray (100–2000 eV) detectors, particularly for synchrotron applications, because of their ability to obtain energy resolutions below 10 eV at count rates approaching 10 kcps. In order to achieve useful solid detection angles with these very small detectors, they are typically deployed in large arrays – currently with 100+ elements, but with 1000 elements being contemplated. In this paper we review a 5-year effort to develop compact, computer controlled low-noise processing electronics for STJ detector arrays, focusing on the major issues encountered and our solutions to them. Of particular interest are our preamplifier design, which can set the STJ operating points under computer control and achieve 2.7 eV energy resolution; our low noise power supply, which produces only 2 nV/√Hz noise at the preamplifier's critical cascode node; our digital processing card that digitizes and digitally processes 32 channels; and an STJ I–V curve scanning algorithm that computes noise as a function of offset voltage, allowing an optimum operating point to be easily selected. With 32 preamplifiers laid out on a custom 3U EuroCard, and the 32 channel digital card in a 3U PXI card format, electronics for a 128 channel array occupy only two small chassis, each the size of a National Instruments 5-slot PXI crate, and allow full array control with simple extensions of existing beam line data collection packages.

  15. Modeling and design of X-rays bidimensional detectors; Modelagem e projeto de detectores bidimensionais para radiacao-X

    Energy Technology Data Exchange (ETDEWEB)

    Quisbert, Elmer Paz Alcon

    2000-03-01

    In this work has been developed the scintillating fiber optic and semiconductor devices based 2-D detector design, modeling and performance evaluation using Monte Carlo methods, for high X-ray energy range (10-140 kV) radiography and tomography applications. These processes allowed us, also, the imaging system parameters and components optimization and appropriate detector design. The model estimated the detectors performance parameters (DQE, MTF and SNR), and radiation risk (in terms of mean absorbed dose in the patient) and to show up how the sequence of physical processes in X-ray detection influence the performance of this imaging PFOC detectors. In this way, the modeling of the detector includes the statistics of the spatial distribution of absorbed X-rays and of X-ray to light conversion, its transmission, and the light quanta conversion into electrons. Also contributions to noise from the detection system chain is included, mainly the CCD detector ambient noise. Performance prediction, based on calculation taken from simulations, illustrates how such detectors meet the exacting requirements of some medical and industrial applications. Also, it is envisaged that our modeling procedure of the imaging system will be suitable not only for investigating how the system components should be best designed but for CT and RD system performance prediction. The powerful techniques would enable us to give advice for future development, in this field, in search of more dose-efficient imaging systems. (author)

  16. A novel wafer-scale CMOS APS X-ray detector for breast cancer diagnosis using X-ray diffraction studies

    Science.gov (United States)

    Konstantinidis, A.; Zheng, Y.; Philip, D.; Vinnicombe, S.; Speller, R.

    2012-12-01

    The current study uses a novel large area (12.8 cm × 13.1 cm) complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) X-ray detector, named Dynamic range Adjustable for Medical Imaging Technology (DynAMITe), for breast cancer diagnosis. The detector consists of two geometrically superimposed grids: a) 2560 × 2624 fine-pitch grid of pixels (50 μm pitch), named Sub-Pixels (SP camera), for low intrinsic noise and high spatial resolution and b) 1280 × 1312 large-pitch grid of pixels (100 μm pitch), named Pixels (P camera), for high dynamic range. X-ray performance characterization measurements show that the detective quantum efficiency (DQE) of the SP camera is in the range 0.7-0.75 at low spatial frequencies using a tungsten (W) anode X-ray source at 28 kV. Hence, the detector is suitable for mammography. Furthermore, we used the SP camera to combine mammograms with angle dispersive X-ray diffraction (ADXRD) measurements in order to apply the X-ray biopsy concept in one examination. The results show that ADXRD technique indicates the presence of cancer in suspicious areas on the mammogram. Hence, it could be used to determine the region affected by cancer and assist in planning surgery. This study is the proof of concept that mammography and ADXRD can be combined in one examination.

  17. An X-ray imaging device based on a GEM detector with delay-line readout

    Science.gov (United States)

    Zhou, Yi; Li, Cheng; Sun, Yong-Jie; Shao, Ming

    2010-01-01

    An X-ray imaging device based on a triple-GEM (Gas Electron Multiplier) detector, a fast delay-line circuit with 700 MHz cut-off frequency and two dimensional readout strips with 150 μm width on the top and 250 μm width on the bottom, is designed and tested. The localization information is derived from the propagation time of the induced signals on the readout strips. This device has a good spatial resolution of 150 μm and works stably at an intensity of 105 Hz/mm2 with 8 keV X-rays.

  18. X-ray inspection of composite materials for aircraft structures using detectors of Medipix type

    Science.gov (United States)

    Jandejsek, I.; Jakubek, J.; Jakubek, M.; Prucha, P.; Krejci, F.; Soukup, P.; Turecek, D.; Vavrik, D.; Zemlicka, J.

    2014-05-01

    This work presents an overview of promising X-ray imaging techniques employed for non-destructive defectoscopy inspections of composite materials intended for the Aircraft industry. The major emphasis is placed on non-tomographic imaging techniques which do not require demanding spatial and time measurement conditions. Imaging methods for defects visualisation, delamination detection and porosity measurement of various composite materials such as carbon fibre reinforced polymers and honeycomb sendwiches are proposed. We make use of the new large area WidePix X-ray imaging camera assembled from up to 100 edgeless Medipix type detectors which is highly suitable for this type of measurements.

  19. X-ray detectors for diffraction studies and their use with synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Milch, J.

    1976-02-01

    All techniques for X-ray diffraction studies on biological materials exhibit certain limitations. The characteristics of several X-ray detection systems, namely film, multiwire proportional counter and image intensified TV, are discussed and compared for application to specific biological studies. For the high count-rate situation existing at a synchrotron, it is shown that film is a good choice, but that the image intensified TV exhibits significant advantages. The details of such a system now being used at Princeton with a low intensity source are given and current results presented.

  20. Employing a Cerenkov detector for the thickness measurement of X-rays in a scattering background

    Institute of Scientific and Technical Information of China (English)

    LI Shu-Wei; KANG Ke-Jun; WANG Yi; LI Jin; LI Yuan-Jing; ZHANG Qing-Jun

    2010-01-01

    The variation in environmental scattering background is a major source of systematic errors in X-ray inspection and measurement systems.As the energy of these photons consisting of environmental scattering background is much lower generally,the Cerenkov detectors having the detection threshold are likely insensitive to them and able to exclude their influence.A thickness measurement experiment is designed to verify the idea by employing a Cerenkov detector and an ionizing chamber for comparison.Furthermore,it is also found that the application of the Cerenkov detectors is helpful to exclude another systematic error from the variation of low energy components in the spectrum incident on the detector volume.

  1. Development of an X-ray detector using photodiodes; Desarrollo de un detector de rayos X usando fotodiodos

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez G, J.; Azorin V, J. C.; Sosa A, M. A.; Ceron, P., E-mail: gonzalezgj2012@licifug.ugto.mx [Universidad de Guanajuato, Division de Ciencias e Ingenierias, Loma del Bosque No. 103, Col. Lomas del Campestre, 37150 Leon, Guanajuato (Mexico)

    2016-10-15

    Currently the radiation detectors for medical applications are very high value in the market and are difficult to access as training material. In the Sciences and Engineering Division of the Guanajuato University (Mexico) investigations are carried out related to ionizing radiations, especially with X-rays. To overcome the lack of materials has had to resort to borrowing equipment from other institutions, so its use and availability are intermittent. For these reasons is proposed to design and implement an X-ray detector for the use of the work group and the University. This work aims to build an X-ray semiconductor detector using inexpensive and affordable materials, is also proposed the use of a photodiode sensor and an Arduino analog-digital card and a LCD display showing the data. (Author)

  2. Operation of an InGrid based X-ray detector at the CAST experiment

    Energy Technology Data Exchange (ETDEWEB)

    Krieger, Christoph; Desch, Klaus; Kaminski, Jochen; Lupberger, Michael [Physikalisches Institut, Universitaet Bonn, Nussallee 12, 53115 Bonn (Germany)

    2015-07-01

    The CERN Axion Solar Telescope (CAST) is searching for axions and other new particles emerging from the Sun and coupling to photons. Those particles are converted into soft X-ray photons in a high magnetic field. To enhance sensitivity for physics beyond the Standard Model it is necessary to cope with weak couplings and low energies, thus requiring an efficient background discrimination as well as a detection threshold below 1 keV. Both requirements are fulfilled by an X-ray detector based on the combination of a Micromegas gas amplification stage with a highly integrated pixel chip (InGrid) which allows to make full use of the Micromegas structure's granularity. The necessary precision in fabrication is achieved by the use of photolithographic postprocessing techniques. The high spatial resolution allows for a topological suppression of background events originating from cosmic rays as well as for the low detection threshold as single electrons can be detected. After the detector's energy threshold was evaluated at an X-ray generator to be low enough to allow for the detection of the carbon K{sub α} line at 277 eV, the detector was mounted at one of CAST's X-ray telescopes and installed along with the necessary infrastructure in 2014. The data taken during the CAST run 2014 is being analysed. Background studies and rates are presented as a first result.

  3. 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...

  4. 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.

  5. Deconvolving the temporal response of photoelectric x-ray detectors for the diagnosis of pulsed radiations.

    Science.gov (United States)

    Zou, Shiyang; Song, Peng; Guo, Liang; Pei, Wenbing

    2013-09-01

    Based on the conjugate gradient method, a simple algorithm is presented for deconvolving the temporal response of photoelectric x-ray detectors (XRDs) to reconstruct the resolved time-dependent x-ray fluxes. With this algorithm, we have studied the impact of temporal response of XRD on the radiation diagnosis of hohlraum heated by a short intense laser pulse. It is found that the limiting temporal response of XRD not only postpones the rising edge and peak position of x-ray pulses but also smoothes the possible fluctuations of radiation fluxes. Without a proper consideration of the temporal response of XRD, the measured radiation flux can be largely misinterpreted for radiation pulses of a hohlraum heated by short or shaped laser pulses.

  6. Study of Scintillator thickness optimization of lens-coupled X-ray imaging detectors

    Science.gov (United States)

    Xie, H.; Du, G.; Deng, B.; Chen, R.; Xiao, T.

    2016-03-01

    Lens-coupled X-ray in-direct imaging detectors are very popular for high-resolution X-ray imaging at the third generation synchrotron radiation facilities. This imaging system consists of a scintilator producing a visible-light image of X-ray beam, a microscope objective, a mirror reflecting at 90° and a CCD camera. When the thickness of the scintillator is matched with the numerical aperture (NA) of the microscope objective, the image quality of experimental results will be improved obviously. This paper used an imaging system at BL13W beamline of Shanghai Synchrotron Radiation Facility (SSRF) to study the matching relation between the scintillator thickness and the NA of the microscope objective with a real sample. By use of the matching relation between the scintillator thickness and the NA of the microscope objective, the optimal imaging results have been obtained.

  7. Development of an X-ray imaging system with SOI pixel detectors

    Science.gov (United States)

    Nishimura, Ryutaro; Arai, Yasuo; Miyoshi, Toshinobu; Hirano, Keiichi; Kishimoto, Shunji; Hashimoto, Ryo

    2016-09-01

    An X-ray imaging system employing pixel sensors in silicon-on-insulator technology is currently under development. The system consists of an SOI pixel detector (INTPIX4) and a DAQ system based on a multi-purpose readout board (SEABAS2). To correct a bottleneck in the total throughput of the DAQ of the first prototype, parallel processing of the data taking and storing processes and a FIFO buffer were implemented for the new DAQ release. Due to these upgrades, the DAQ throughput was improved from 6 Hz (41 Mbps) to 90 Hz (613 Mbps). The first X-ray imaging system with the new DAQ software release was tested using 33.3 keV and 9.5 keV mono X-rays for three-dimensional computerized tomography. The results of these tests are presented.

  8. Metal screen-film detector MTF at megavoltage x-ray energies.

    Science.gov (United States)

    Droege, R T; Bjärngard, B E

    1979-01-01

    The MTF of metal screen film detectors used in radiation treatment verification has been measured at 4 and 8 MV x-ray energies. The results show that lead screens provide better resolution than copper screens, and a single-emulsion film offers considerable advantage over the traditional double-emulsion film. A rear lead screen was found to seriously degrade the resolution properties of a front lead screen single-emulsion film detector. The detector MTF was found to be energy dependent. In general, both the low and the high spatial frequency response decreased with increasing x-ray energy. This, in part, accounts for the noticeable image quality difference between 4 and 8 MV radiographs.

  9. Discriminating cosmic muons and X-rays based on rise time using a GEM detector

    Science.gov (United States)

    Wu, Hui-Yin; Zhao, Sheng-Ying; Wang, Xiao-Dong; Zhang, Xian-Ming; Qi, Hui-Rong; Zhang, Wei; Wu, Ke-Yan; Hu, Bi-Tao; Zhang, Yi

    2016-08-01

    Gas electron multiplier (GEM) detectors have been used in cosmic muon scattering tomography and neutron imaging over the last decade. In this work, a triple GEM device with an effective readout area of 10 cm × 10 cm is developed, and a method of discriminating between cosmic muons and X-rays based on rise time is tested. The energy resolution of the GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. Analysis of the complete signal-cycles allows us to get the rise time and pulse heights. The experiment result indicates that cosmic muons and X-rays can be discriminated with an appropriate rise time threshold. Supported by National Natural Science Foundation of China (11135002, 11275235, 11405077, 11575073)

  10. Silicon strip detectors for two-dimensional soft X-ray imaging at normal incidence

    Energy Technology Data Exchange (ETDEWEB)

    Rato Mendes, P. E-mail: rato@lip.pt; Abreu, M.C.; 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, L.M.; Prino, F.; Ramello, L.; Rodrigues, S.; Sitta, M.; Sousa, P.; Swientek, K.; Taibi, A.; Tuffanelli, A.; Wheadon, R.; Wiacek, P

    2003-08-21

    A simple prototype system for static two-dimensional soft X-ray imaging using silicon microstrip detectors irradiated at normal incidence is presented. Radiation sensors consist of single-sided silicon detectors made from 300 {mu}m thick wafers, read by RX64 ASICs. Data acquisition and control is performed by a Windows PC workstation running dedicated LabVIEW routines, connected to the sensors through a PCI-DIO-96 interface. Two-dimensional images are obtained by scanning a lead collimator with a thin slit perpendicular to the strip axis, along the whole detector size; the several strip profiles (slices) taken at each position are then put together to form a planar image. Preliminary results are presented, illustrating the high-resolution imaging capabilities of the system with soft X-rays.

  11. Matching X-ray beam and detector properties to protein crystals of different perfection

    Energy Technology Data Exchange (ETDEWEB)

    Nave, Colin, E-mail: colin.nave@diamond.ac.uk [Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom)

    2014-03-18

    Expressions are given to match X-ray data collection facilities to the intrinsic diffraction properties of crystals with different degrees of perfection. An analysis is given of the effect of different beam and detector parameters on the sharpness of recorded diffraction features for macromolecular crystals of different quality. The crystal quality parameters include crystal strain, crystal or mosaic block size and mosaic block misorientation. Calculations are given for instrument parameters such as angular resolution of the detector, beam divergence and wavelength bandpass to be matched to the intrinsic diffraction properties from these crystals with the aim of obtaining the best possible data out of each crystal. Examples are given using typical crystal imperfections obtained from the literature for both room-temperature and cryo-cooled crystals. Possible implications for the choice of X-ray source, beamline design, detector specifications, instrument set-up and data processing are discussed, together with the limitations of the approach.

  12. Assembly and test of the gas pixel detector for X-ray polarimetry

    Science.gov (United States)

    Li, H.; Feng, H.; Muleri, F.; Bellazzini, R.; Minuti, M.; Soffitta, P.; Brez, A.; Spandre, G.; Pinchera, M.; Sgró, C.; Baldini, L.; She, R.; Costa, E.

    2015-12-01

    The gas pixel detector (GPD) dedicated for photoelectric X-ray polarimetry is selected as the focal plane detector for the ESA medium-class mission concept X-ray Imaging and Polarimetry Explorer (XIPE). Here we show the design, assembly, and preliminary test results of a small GPD for the purpose of gas mixture optimization needed for the phase A study of XIPE. The detector is assembled in house at Tsinghua University following a design by the INFN-Pisa group. The improved detector design results in a good uniformity for the electric field. Filled with pure dimethyl ether (DME) at 0.8 atm, the measured energy resolution is 18% at 6 keV and inversely scales with the square root of the X-ray energy. The measured modulation factor is well consistent with that from simulation, up to ~0.6 above 6 keV. The residual modulation is found to be 0.30 ± 0.15 % at 6 keV for the whole sensitive area, which can be translated into a systematic error of less than 1% for polarization measurement at a confidence level of 99%. The position resolution of the detector is about 80 μm in FWHM, consistent with previous studies and sufficient for XIPE requirements.

  13. Development of an X-ray imaging system with SOI pixel detectors

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Ryutaro, E-mail: ryunishi@post.kek.jp [School of High Energy Accelerator Science, SOKENDAI (The Graduate University for Advanced Studies), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Arai, Yasuo; Miyoshi, Toshinobu [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK-IPNS), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Hirano, Keiichi; Kishimoto, Shunji; Hashimoto, Ryo [Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK-IMSS), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan)

    2016-09-21

    An X-ray imaging system employing pixel sensors in silicon-on-insulator technology is currently under development. The system consists of an SOI pixel detector (INTPIX4) and a DAQ system based on a multi-purpose readout board (SEABAS2). To correct a bottleneck in the total throughput of the DAQ of the first prototype, parallel processing of the data taking and storing processes and a FIFO buffer were implemented for the new DAQ release. Due to these upgrades, the DAQ throughput was improved from 6 Hz (41 Mbps) to 90 Hz (613 Mbps). The first X-ray imaging system with the new DAQ software release was tested using 33.3 keV and 9.5 keV mono X-rays for three-dimensional computerized tomography. The results of these tests are presented. - Highlights: • The X-ray imaging system employing the SOI pixel sensor is currently under development. • The DAQ of the first prototype has the bottleneck in the total throughput. • The new DAQ release solve the bottleneck by parallel processing and FIFO buffer. • The new DAQ release was tested using 33.3 keV and 9.5 keV mono X-rays.

  14. In-Orbit Performance of the Hard X-ray Detector on board Suzaku

    CERN Document Server

    Kokubun, M; Takahashi, T; Murakami, T; Tashiro, M; Fukazawa, Y; Kamae, T; Madejski, G M; Nakazawa, K; Yamaoka, K; Terada, Y; Yonetoku, D; Watanabe, S; Tamagawa, T; Mizuno, T; Kubota, A; Isobe, N; Takahashi, I; Sato, G; Takahashi, H; Hong, S; Kawaharada, M; Kawano, N; Mitani, T; Murashima, M; Suzuki, M; Abe, K; Miyawaki, R; Ohno, M; Tanaka, T; Yanagida, T; Itoh, T; Ohnuki, K; Tamura, K; Endo, Y; Hirakuri, S; Hiruta, T; Kitaguchi, T; Kishishita, T; Sugita, S; Takeda, S; Enoto, T; Hirasawa, A; Katsuta, J; Matsumura, S; Onda, K; Sato, M; Ushio, M; Ishikawa, S; Murase, K; Odaka, H; Yaji, Y; Yamada, S; Yamasaki, T; Yuasa, T

    2006-01-01

    The in-orbit performance and calibration of the Hard X-ray Detector (HXD) on board the X-ray astronomy satellite Suzaku are described. Its basic performances, including a wide energy bandpass of 10-600 keV, energy resolutions of ~4 keV (FWHM) at 40 keV and ~11% at 511 keV, and a high background rejection efficiency, have been confirmed by extensive in-orbit calibrations. The long-term gains of PIN-Si diodes have been stable within 1% for half a year, and those of scintillators have decreased by 5-20%. The residual non-X-ray background of the HXD is the lowest among past non-imaging hard X-ray instruments in energy ranges of 15-70 and 150-500 keV. We provide accurate calibrations of energy responses, angular responses, timing accuracy of the HXD, and relative normalizations to the X-ray CCD cameras using multiple observations of the Crab Nebula.

  15. The hard X-ray response of the XIS-CCD for Astro-E: qualification of the X-ray CCD detector

    CERN Document Server

    Nishiuchi, M; Awaki, H; Tsuru, T; Sakano, M; Hamaguchi, K; Murakami, H; Tsunemi, H; Hayashida, K; Kitamoto, S; Miyata, E; Dotani, T; Ozaki, M; Bautz, M; Doty, J; Kissel, S; Foster, R; Ricker, G

    1999-01-01

    We report on the hard X-ray response of the CCD detector for the X-ray imaging spectrometer (XIS), to be launched on the next Japanese X-ray Astronomical Satellite, ASTRO-E, in February 2000. XIS is prepared by an international team, comprised of MIT (USA), ISAS, Osaka University and Kyoto University (JAPAN). We have evaluated the X-ray response of the XIS in its high-energy band (1.5-10 keV). Data from the fluorescent line emission of Al, Cl, Ti, Ni, Fe, Zn, Se were used to construct the response function of the CCD detectors. Details of the response function - including the energy-scale, linearity, energy resolution, quantum efficiency -, are given as a function of incident X-ray energy. We find that the tail component of high-energy photopeaks are produced by events with incomplete charge collection. We also conclude that the size of the charge clouds can be estimated using the shapes of the tail components.

  16. Performance Evaluation of a Modular Detector Unit for X-Ray Computed Tomography

    Directory of Open Access Journals (Sweden)

    Guangshu Hu

    2013-04-01

    Full Text Available A research prototype CT scanner is currently under development in our lab. One of the key components in this project is the CT detector. This paper describes the design and performance evaluation of the modular CT detector unit for our proposed scanner. It consists of a Photodiode Array Assembly which captures irradiating X-ray photons and converts the energy into electrical current, and a mini Data Acquisition System which performs current integration and converts the analog signal into digital samples. The detector unit can be easily tiled together to form a CT detector. Experiments were conducted to characterize the detector performance both at the single unit level and system level. The noise level, linearity and uniformity of the proposed detector unit were reported and initial imaging studies were also presented which demonstrated the potential application of the proposed detector unit in actual CT scanners.

  17. Energy-windowed, pixellated X-ray diffraction using the Pixirad CdTe detector

    Science.gov (United States)

    O'Flynn, D.; Bellazzini, R.; Minuti, M.; Brez, A.; Pinchera, M.; Spandre, G.; Moss, R.; Speller, R. D.

    2017-01-01

    X-ray diffraction (XRD) is a powerful tool for material identification. In order to interpret XRD data, knowledge is required of the scattering angles and energies of X-rays which interact with the sample. By using a pixellated, energy-resolving detector, this knowledge can be gained when using a spectrum of unfiltered X-rays, and without the need to collimate the scattered radiation. Here we present results of XRD measurements taken with the Pixirad detector and a laboratory-based X-ray source. The cadmium telluride sensor allows energy windows to be selected, and the 62 μm pixel pitch enables accurate spatial information to be preserved for XRD measurements, in addition to the ability to take high resolution radiographic images. Diffraction data are presented for a variety of samples to demonstrate the capability of the technique for materials discrimination in laboratory, security and pharmaceutical environments. Distinct diffraction patterns were obtained, from which details on the molecular structures of the items under study were determined.

  18. Trends in hard X-ray fluorescence mapping: environmental applications in the age of fast detectors.

    Science.gov (United States)

    Lombi, E; de Jonge, M D; Donner, E; Ryan, C G; Paterson, D

    2011-06-01

    Environmental samples are extremely diverse but share a tendency for heterogeneity and complexity. This heterogeneity poses methodological challenges when investigating biogeochemical processes. In recent years, the development of analytical tools capable of probing element distribution and speciation at the microscale have allowed this challenge to be addressed. Of these available tools, laterally resolved synchrotron techniques such as X-ray fluorescence mapping are key methods for the in situ investigation of micronutrients and inorganic contaminants in environmental samples. This article demonstrates how recent advances in X-ray fluorescence detector technology are bringing new possibilities to environmental research. Fast detectors are helping to circumvent major issues such as X-ray beam damage of hydrated samples, as dwell times during scanning are reduced. They are also helping to reduce temporal beamtime requirements, making particularly time-consuming techniques such as micro X-ray fluorescence (μXRF) tomography increasingly feasible. This article focuses on μXRF mapping of nutrients and metalloids in environmental samples, and suggests that the current divide between mapping and speciation techniques will be increasingly blurred by the development of combined approaches.

  19. A Large Area Detector proposed for the Large Observatory for X-ray Timing (LOFT)

    CERN Document Server

    Zane, S; Kennedy, T; Feroci, M; Herder, J -W Den; Ahangarianabhari, M; Argan, A; Azzarello, P; Baldazzi, G; Barret, D; Bertuccio, G; Bodini, P; Bozzo, E; Cadoux, F; Cais, P; Campana, R; Coker, J; Cros, A; Del Monte, E; De Rosa, A; Di Cosimo, S; Donnarumma, I; Evangelista, Y; Favre, Y; Feldman, C; Fraser, G; Fuschino, F; Grassi, M; Hailey, M R; Hudec, R; Labanti, C; Macera, D; Malcovati, P; Marisaldi, M; Martindale, A; Mineo, T; Muleri, F; Nowak, M; Orlandini, M; Pacciani, L; Perinati, E; Petracek, V; Pohl, M; Rachevski, A; Smith, P; Santangelo, A; Seyler, J -Y; Schmid, C; Soffitta, P; Suchy, S; Tenzer, C; Uttley, P; Vacchi, A; Zampa, G; Zampa, N; Wilms, J; Winter, B

    2012-01-01

    The Large Observatory for X-ray Timing (LOFT) is one of the four candidate ESA M3 missions considered for launch in the 2022 time-frame. It is specifically designed to perform fast X-ray timing and probe the status of the matter near black holes and neutron stars. The LOFT scientific payload is composed of a Large Area Detector (LAD) and a Wide Field Monitor (WFM). The LAD is a 10 m2-class pointed instrument with 20 times the collecting area of the best past timing missions (such as RXTE) over the 2-30 keV range, which holds the capability to revolutionize studies of X-ray variability down to the millisecond time scales. Its ground-breaking characteristic is a low mass per unit surface, enabling an effective area of ~10 m^2 (@10 keV) at a reasonable weight. The development of such large but light experiment, with low mass and power per unit area, is now made possible by the recent advancements in the field of large-area silicon detectors - able to time tag an X-ray photon with an accuracy <10 {\\mu}s and an...

  20. A new type of cylindrical a-Si:H X-ray detector

    Energy Technology Data Exchange (ETDEWEB)

    Link, D.; Keppner, H.; Chabloz, P.; Shah, A. [Univ. de Neuchatel (Switzerland). Lab. de Microtechnique; Germond, J.F.; Haefliger, J.M. [Hopital Communal, La Chaux-de-Fonds (Switzerland). Service de Radio-oncologie; Pochon, Y.; Frosio, G. [Ecole d`Ingenieurs du Canton de Neuchatel, Le Locle (Switzerland)

    1996-12-31

    The present paper describes a new type of cylindrical X-ray detector based on thick amorphous silicon diodes. The authors report on the successful development of these detectors that have diameters as small as 3mm. The effect of silane dilution is hydrogen on deposition rate, powder formation, layer adhesion and detector performance is discussed. A set of deposition parameters is presented, that allows a reasonable compromise between the mentioned effects. First prototypes of this type of dosimeter have been characterized with the radiation from a {sup 60}Co source in a hospital. The corresponding results and interpretation are given in this paper.

  1. An alignment method for the ATLAS end-cap TRT detector using a narrow monochromatic X-ray beam

    CERN Document Server

    Åkesson, T; Dixon, N; Dolgoshein, B A; Eerola, Paule Anna Mari; Farthouat, Philippe; Fedin, O; Froidevaux, Daniel; Gavrilenko, I; Hajduk, Z; Hauviller, Claude; Ivanov, V; Ivochkin, V G; Jelamkov, A; Konovalov, S V; Lichard, P; Lundberg, B; Muraviev, S; Nadtochy, A; Nevski, P; Peshekhonov, V D; Platonov, Yu P; Price, M; Romaniouk, A; Shchegelskii, V; Shmeleva, A; Smirnov, A; Smirnov, S; Sosnovtsev, V V

    2001-01-01

    The end-cap transition radiation tracker (TRT), consisting of 36 modules (wheels), is being constructed as a part of the ATLAS Inner Detector at the CERN LHC. This paper describes a method for determining the wire positions inside the straw proportional tubes (SPT), which are the basic building blocks of the ATLAS TRT, with an accuracy of better than 10 mu m. The procedure involves moving a narrow monochromatic X-ray beam across the straw and measuring the counting rate as a function of the position of the X-ray beam in the straw. To achieve this goal, a beam directing device (BDD), providing the possibility to direct the X-ray beam in a chosen direction within some solid angle and supplying an accurate angular measurement system, has been constructed. The results of the wire position measurements performed using this BDD on a full-scale mechanical prototype end-cap wheel of the TRT are presented in this paper. (11 refs).

  2. Counting and integrating microelectronics development for direct conversion X-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kraft, E.

    2008-02-15

    A novel signal processing concept for X-ray imaging with directly converting pixelated semiconductor sensors is presented. The novelty of this approach compared to existing concepts is the combination of charge integration and photon counting in every single pixel. Simultaneous operation of both signal processing chains extends the dynamic range beyond the limits of the individual schemes and allows determination of the mean photon energy. Medical applications such as X-ray computed tomography can benefit from this additional spectral information through improved contrast and the ability to determine the hardening of the tube spectrum due to attenuation by the scanned object. A prototype chip in 0.35-micrometer technology has been successfully tested. The pixel electronics are designed using a low-swing differential current mode logic. Key element is a configurable feedback circuit for the charge sensitive amplifier which provides continuous reset, leakage current compensation and replicates the input signal for the integrator. The thesis focusses on the electronic characterization of a second generation prototype chip and gives a detailed discussion of the circuit design. (orig.)

  3. Assembly and Test of the Gas Pixel Detector for X-ray Polarimetry

    CERN Document Server

    Li, H; Muleri, F; Bellazzini, R; Minuti, M; Soffitta, P; Brez, A; Spandre, G; Pinchera, M; Sgro, C; Baldini, L; She, R; Costa, E

    2015-01-01

    The gas pixel detector (GPD) dedicated for photoelectric X-ray polarimetry is selected as the focal plane detector for the ESA medium-class mission concept X-ray Imaging and Polarimetry Explorer (XIPE). Here we show the design, assembly, and preliminary test results of a small GPD for the purpose of gas mixture optimization needed for the phase A study of XIPE. The detector is assembled in house at Tsinghua University following a design by the INFN-Pisa group. The improved detector design results in a good uniformity for the electric field. Filled with pure dimethyl ether (DME) at 0.8 atm, the measured energy resolution is 18% at 6 keV and inversely scales with the square root of the X-ray energy. The measured modulation factor is well consistent with that from simulation, up to ~0.6 above 6 keV. The residual modulation is found to be 0.30% +/- 0.15% at 6 keV for the whole sensitive area, which can be translated into a systematic error of less than 1% for polarization measurement at a confidence level of 99%....

  4. Implementation of digital multiplexing for high resolution X-ray detector arrays.

    Science.gov (United States)

    Sharma, P; Swetadri Vasan, S N; Titus, A H; Cartwright, A N; Bednarek, D R; Rudin, S

    2012-01-01

    We describe and demonstrate for the first time the use of the novel Multiple Module Multiplexer (MMMIC) for a 2×2 array of new electron multiplying charge coupled device (EMCCD) based x-ray detectors. It is highly desirable for x-ray imaging systems to have larger fields of view (FOV) extensible in two directions yet to still be capable of doing high resolution imaging over regions-of-interest (ROI). The MMMIC achieves these goals by acquiring and multiplexing data from an array of imaging modules thereby enabling a larger FOV, and at the same time allowing high resolution ROI imaging through selection of a subset of modules in the array. MMMIC also supports different binning modes. This paper describes how a specific two stage configuration connecting three identical MMMICs is used to acquire and multiplex data from a 2×2 array of EMCCD based detectors. The first stage contains two MMMICs wherein each MMMIC is getting data from two EMCCD detectors. The multiplexed data from these MMMICs is then forwarded to the second stage MMMIC in the similar fashion. The second stage that has only one MMMIC gives the final 12 bit multiplexed data from four modules. This data is then sent over a high speed Camera Link interface to the image processing computer. X-ray images taken through the 2×2 array of EMCCD based detectors using this two stage configuration of MMMICs are shown successfully demonstrating the concept.

  5. Evaluation and development of X-ray detectors for dosimetry; Evaluierung und Entwicklung von Roentgendetektoren fuer die Dosimetrie

    Energy Technology Data Exchange (ETDEWEB)

    Boehnel, Michael

    2012-03-28

    This thesis presents the development and evaluation of a new personal dosemeter, based on the technology of energy-resolving pixelated photon-counting X-ray detectors. The basis of the development is a detailed study of the Timepix detector. The main focus is on the investigation of the energy resolving properties of the Timepix detector in counting mode and in the spectroscopic time-over-threshold mode. The approach for the production of fluorescence radiation for the detector calibration, necessary for the experiments, is presented. By using Monte Carlo simulations the spectral distribution of the resulting fluorescence spectra in dependence on the fluorescence material, the used primary X-ray radiation and the arrangement of the laboratory setup is discussed. Besides the actual fluorescence lines, the simulated calibration spectra also contain the background of scattered primary X-ray photons and fluorescence radiation contributions from parts of the experimental setup. Furthermore, the simulated spectra exhibit the corrected intensity conditions of the fluorescence emissions of the K- and L-shell. These calibration spectra permit a better match of measurements and simulations than the simplified fluorescence spectra used so far. For the detector calibration in counting mode, accelerated energy calibration methods are introduced. From measuring energy deposition spectra, the energy resolution of single pixels and the energy resolution of the complete detector could be determined by the application of a global energy calibration. It was shown that the influence of the threshold dispersion broadens the energy resolution of the single pixels, depending on the given energy deposition. The resulting energy resolution of the whole pixel matrix is thereby reduced. The negative effect of the threshold dispersion can be eliminated by the application of a single-pixel calibration. The relative energy resolution of the Timepix detector operated in the counting mode can

  6. 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

  7. The high resolution X-ray imaging detector planes for the MIRAX mission

    Science.gov (United States)

    Rodrigues, B. H. G.; Grindlay, J. E.; Allen, B.; Hong, J.; Barthelmy, S.; Braga, J.; D'Amico, F.; Rothschild, R. E.

    2013-09-01

    The MIRAX X-ray observatory, the first Brazilian-led astrophysics space mission, is designed to perform an unprecedented wide-field, wide-band hard X-ray (5-200 keV) survey of Galactic X-ray transient sources. In the current configuration, MIRAX will carry a set of four coded-masks telescopes with high spatial resolution Cadmium Zinc Telluride (CZT) detector planes, each one consisting of an array of 64 closely tiled CZT pixelated detectors. Taken together, the four telescopes will have a total detection area of 959 cm2, a large field of view (60° × 60° FWHM), high angular resolution for this energy range (6 arcmin) and very good spectral resolution ( ~ 2 keV @ 60 keV). A stratospheric balloon-borne prototype of one of the MIRAX telescopes has been developed, tested and flown by the Harvard-Smithsonian Center for Astrophysics (CfA) as part of the ProtoEXIST program. In this paper we show results of validation and calibration tests with individual CZT detectors of the ProtoEXIST second generation experiment (P2). Each one of 64 detector units of the P2 detector plane consists of an ASIC, developed by Caltech for the NuSTAR telescope, hybridized to a CZT crystal with 0.6 mm pixel size. The performance of each detector was evaluated using radioactive sources in the laboratory. The calibration results show that the P2 detectors have average energy resolution of ~ 2.1 keV @ 60 keV and 2.3 @ 122 keV. P2 was also successfully tested on near-space environment on a balloon flight, demonstrating the detector unit readiness for integration on a space mission telescope, as well as satisfying all MIRAX mission requirements.

  8. Elemental mapping in a contemporary miniature by full-field X-ray fluorescence imaging with gaseous detector vs. scanning X-ray fluorescence imaging with polycapillary optics

    Science.gov (United States)

    Silva, A. L. M.; Cirino, S.; Carvalho, M. L.; Manso, M.; Pessanha, S.; Azevedo, C. D. R.; Carramate, L. F. N. D.; Santos, J. P.; Guerra, M.; Veloso, J. F. C. A.

    2017-03-01

    Energy dispersive X-ray imaging can be used in several research fields and industrial applications. Elemental mapping through energy dispersive X-ray imaging technique has become a promising method to obtain positional distribution of specific elements in a non-destructive way. To obtain the elemental distribution of a sample it is necessary to use instruments capable of providing a precise positioning together with a good energy resolution. Polycapillary beams together with silicon drift chamber detectors are used in several commercial systems and are considered state-of-the-art spectrometers, however they are usually very costly. A new concept of large energy dispersive X-ray imaging systems based on gaseous radiation detectors emerged in the last years enabling a promising 2D elemental detection at a very reduced price. The main goal of this work is to analyze a contemporary Indian miniature with both X-ray fluorescence imaging systems, the one based on a gaseous detector 2D-THCOBRA and the state-of-the-art spectrometer M4 Tornado, from Bruker. The performance of both systems is compared and evaluated in the context of the sample's analysis.

  9. Performance characteristics needed for protein crystal diffraction x-ray detectors.

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, E. M.

    1999-09-21

    During the 1990's, macromolecular crystallography became progressively more dependent on synchrotrons X-ray sources for diffraction data collection. Detectors of this diffraction data at synchrotrons beamlines have evolved over the decade, from film to image phosphor plates, and then to CCD systems. These changes have been driven by the data quality and quantity improvements each newer detector technology provided. The improvements have been significant. It is likely that newer detector technologies will be adopted at synchrotron beamlines for crystallographic diffraction data collection in the future, but these technologies will have to compete with existing CCD detector systems which are already excellent and are getting incrementally better in terms of size, speed, efficiency, and resolving power. Detector development for this application at synchrotrons must concentrate on making systems which are bigger and faster than CCDs and which can capture weak data more efficiently. And there is a need for excellent detectors which are less expensive than CCD systems.

  10. Heavy metallic oxide nanoparticles for enhanced sensitivity in semiconducting polymer x-ray detectors.

    Science.gov (United States)

    Intaniwet, A; Mills, C A; Shkunov, M; Sellin, P J; Keddie, J L

    2012-06-15

    Semiconducting polymers have previously been used as the transduction material in x-ray dosimeters, but these devices have a rather low detection sensitivity because of the low x-ray attenuation efficiency of the organic active layer. Here, we demonstrate a way to overcome this limitation through the introduction of high density nanoparticles having a high atomic number (Z) to increase the x-ray attenuation. Specifically, bismuth oxide (Bi(2)O(3)) nanoparticles (Z = 83 for Bi) are added to a poly(triarylamine) (PTAA) semiconducting polymer in the active layer of an x-ray detector. Scanning electron microscopy (SEM) reveals that the Bi(2)O(3) nanoparticles are reasonably distributed in the PTAA active layer. The reverse bias dc current-voltage characteristics for PTAA-Bi(2)O(3) diodes (with indium tin oxide (ITO) and Al contacts) have similar leakage currents to ITO/PTAA/Al diodes. Upon irradiation with 17.5 keV x-ray beams, a PTAA device containing 60 wt% Bi(2)O(3) nanoparticles demonstrates a sensitivity increase of approximately 2.5 times compared to the plain PTAA sensor. These results indicate that the addition of high-Z nanoparticles improves the performance of the dosimeters by increasing the x-ray stopping power of the active volume of the diode. Because the Bi(2)O(3) has a high density, it can be used very efficiently, achieving a high weight fraction with a low volume fraction of nanoparticles. The mechanical flexibility of the polymer is not sacrificed when the inorganic nanoparticles are incorporated.

  11. Investigation of GEM-Micromegas detector on X-ray beam of synchrotron radiation

    Science.gov (United States)

    Zhang, Yu-Lian; Qi, Hui-Rong; Hu, Bi-Tao; Fan, Sheng-Nan; Wang, Bo; Liu, Mei; Zhang, Jian; Liu, Rong-Guang; Chang, Guang-Cai; Liu, Peng; Ouyang, Qun; Chen, Yuan-Bo; Yi, Fu-Ting

    2014-04-01

    To reduce the discharge of the standard bulk Micromegas and GEM detectors, a GEM-Micromegas detector was developed at the Institute of High Energy Physics. Taking into account the advantages of the two detectors, one GEM foil was set as a preamplifier on the mesh of Micromegas in the structure and the GEM preamplification decreased the working voltage of Micromegas to significantly reduce the effect of the discharge. At the same gain, the spark probability of the GEM-Micromegas detector can be reduced to a factor 0.01 compared to the standard Micromegas detector, and an even higher gain could be obtained. This paper describes the performance of the X-ray beam detector that was studied at 1W2B Laboratory of Beijing Synchrotron Radiation Facility. Finally, the result of the energy resolution under various X-ray energies was given in different working gases. This indicates that the GEM-Micromegas detector has an energy response capability in an energy range from 6 keV to 20 keV and it could work better than the standard bulk-Micromegas.

  12. A setup for soft proton irradiation of X-ray detectors for future astronomical space missions

    CERN Document Server

    Diebold, Sebastian; Del Monte, Ettore; Feroci, Marco; Jochum, Josef; Kendziorra, Eckhard; Perinati, Emanuele; Rachevski, Alexandre; Santangelo, Andrea; Tenzer, Christoph; Vacchi, Andrea; Zampa, Gianluigi; Zampa, Nicola

    2013-01-01

    Protons that are trapped in the Earth's magnetic field are one of the main threats to astronomical X-ray observatories. Soft protons, in the range from tens of keV up to a few MeV, impinging on silicon X-ray detectors can lead to a significant degradation of the detector performance. Especially in low earth orbits an enhancement of the soft proton flux has been found. A setup to irradiate detectors with soft protons has been constructed at the Van-de-Graaff accelerator of the Physikalisches Institut of the University of T\\"ubingen. Key advantages are a high flux uniformity over a large area, to enable irradiations of large detectors, and a monitoring system for the applied fluence, the beam uniformity, and the spectrum, that allows testing of detector prototypes in early development phases, when readout electronics are not yet available. Two irradiation campaigns have been performed so far with this setup. The irradiated detectors are silicon drift detectors, designated for the use on-board the LOFT space mis...

  13. The simulation of charge sharing in semiconductor X-ray pixel detectors

    CERN Document Server

    Mathieson, K; O'Shea, V; Passmore, M S; Rahman, M; Smith, K M; Watt, J; Whitehill, C

    2002-01-01

    Two simulation packages were used to model the sharing of charge, due to the scattering and diffusion of carriers, between adjacent pixel elements in semiconductors X-ray detectors. The X-ray interaction and the consequent multiple scattering was modelled with the aid of the Monte Carlo package, MCNP. The resultant deposited charge distribution was then used to create the charge cloud profile in the finite element semiconductor simulation code MEDICI. The analysis of the current pulses induced on pixel electrodes for varying photon energies was performed for a GaAs pixel detector. For a pixel pitch of 25 mu m, the charge lost to a neighbouring pixel was observed to be constant, at 0.6%, through the energies simulated. Ultimately, a fundamental limit on the pixel element size for imaging and spectroscopic devices may be set due to these key physical principles.

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

    Science.gov (United States)

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

    2011-08-01

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

  15. Interconnect and bonding techniques for pixelated X-ray and gamma-ray detectors

    Science.gov (United States)

    Schneider, A.; Veale, M. C.; Duarte, D. D.; Bell, S. J.; Wilson, M. D.; Lipp, J. D.; Seller, P.

    2015-02-01

    In the last decade, the Detector Development Group at the Technology Department of the Science and Technology Facilities Council (STFC), U.K., established a variety of fabrication and bonding techniques to build pixelated X-ray and γ-ray detector systems such as the spectroscopic X-ray imaging detector HEXITEC [1]. The fabrication and bonding of such devices comprises a range of processes including material surface preparation, photolithography, stencil printing, flip-chip and wire bonding of detectors to application-specific integrated circuits (ASIC). This paper presents interconnect and bonding techniques used in the fabrication chain for pixelated detectors assembled at STFC. For this purpose, detector dies (~ 20× 20 mm2) of high quality, single crystal semiconductors, such as cadmium zinc telluride (CZT) are cut to the required thickness (up to 5mm). The die surfaces are lapped and polished to a mirror-finish and then individually processed by electroless gold deposition combined with photolithography to form 74× 74 arrays of 200 μ m × 200 μ m pixels with 250 μ m pitch. Owing to a lack of availability of CZT wafers, lithography is commonly carried out on individual detector dies which represents a significant technical challenge as the edge of the pixel array and the surrounding guard band lies close to the physical edge of the crystal. Further, such detector dies are flip-chip bonded to readout ASIC using low-temperature curing silver-loaded epoxy so that the stress between the bonded detector die and the ASIC is minimized. In addition, this reduces crystalline modifications of the detector die that occur at temperature greater than 150\\r{ }C and have adverse effects on the detector performance. To allow smaller pitch detectors to be bonded, STFC has also developed a compression cold-weld indium bump bonding technique utilising bumps formed by a photolithographic lift-off technique.

  16. CdTe Focal Plane Detector for Hard X-Ray Focusing Optics

    Science.gov (United States)

    Seller, Paul; Wilson, Matthew D.; Veale, Matthew C.; Schneider, Andreas; Gaskin, Jessica; Wilson-Hodge, Colleen; Christe, Steven; Shih, Albert Y.; Inglis, Andrew; Panessa, Marco

    2015-01-01

    The demand for higher resolution x-ray optics (a few arcseconds or better) in the areas of astrophysics and solar science has, in turn, driven the development of complementary detectors. These detectors should have fine pixels, necessary to appropriately oversample the optics at a given focal length, and an energy response also matched to that of the optics. Rutherford Appleton Laboratory have developed a 3-side buttable, 20 millimeter x 20 millimeter CdTe-based detector with 250 micrometer square pixels (80 x 80 pixels) which achieves 1 kiloelectronvolt FWHM (Full-Width Half-Maximum) @ 60 kiloelectronvolts and gives full spectroscopy between 5 kiloelectronvolts and 200 kiloelectronvolts. An added advantage of these detectors is that they have a full-frame readout rate of 10 kilohertz. Working with NASA Goddard Space Flight Center and Marshall Space Flight Center, 4 of these 1 millimeter-thick CdTe detectors are tiled into a 2 x 2 array for use at the focal plane of a balloon-borne hard-x-ray telescope, and a similar configuration could be suitable for astrophysics and solar space-based missions. This effort encompasses the fabrication and testing of flight-suitable front-end electronics and calibration of the assembled detector arrays. We explain the operation of the pixelated ASIC readout and measurements, front-end electronics development, preliminary X-ray imaging and spectral performance, and plans for full calibration of the detector assemblies. Work done in conjunction with the NASA Centers is funded through the NASA Science Mission Directorate Astrophysics Research and Analysis Program.

  17. Transmission properties of barite mortar using X-ray spectra measured with Cd Te detector

    Energy Technology Data Exchange (ETDEWEB)

    Santos, J. C.; Mariano, L.; Costa, P. R. [Universidade de Sao Paulo, Instituto de Fisica, Rua do Matao Travessa R. 187, Cidade Universitaria, 05508-090 Sao Paulo (Brazil); Tomal, A., E-mail: josilene@usp.br [Universidade Federal de Goias, Instituto de Fisica, Campus Samambaia, 74001-970 Goiania (Brazil)

    2014-08-15

    Current methods for calculating X-ray shielding barriers do not take into account spectral distribution of the beam transmitted by the protective material. This consideration is important in dose estimations for radiation workers and general public in diagnostic radiology facilities. The aim of the present study was to estimate barite mortar attenuation curves using X-ray spectra weighted by a workload distribution. These curves were described in units of ambient dose equivalent (H (10)), since it is the radiation quantity adopted by IAEA for dose assessment in medical environment. Attenuation curves were determined using the optimized model for shielding evaluation presented by Costa and Caldas (2002). Workload distribution presented by Simpkin (1996), measured primary spectra and mass attenuation coefficients of barite mortar were used as input data in this model. X-ray beams in diagnostic energy range were generated by an industrial X-ray tube with 3 mm of aluminum additional filtration. Primary experimental spectra were measured by a Cd Te detector and corrected by the response function of detector by means of a stripping procedure. Air kerma measurements were performed using an ionization chamber for normalization purpose of the spectra. The corrected spectra presented good agreement with spectra generated by a semi-empirical model. The variation of the ambient dose equivalent as a function of barite mortar thickness was calculated. Using these data, it was estimated the optimized thickness of protective barrier needed for shielding a particular area in an X-ray imaging facility. The results obtained for primary protective barriers exhibit qualitative agreement with those presented in literature. (Author)

  18. The High Resolution X-Ray Imaging Detector Planes for the MIRAX Mission

    CERN Document Server

    Rodrigues, Barbara H G; Allen, Branden; Hong, Jaesub; Barthelmy, Scott; Braga, Joao; D'Amico, Flavio; Rothschild, Richard E

    2013-01-01

    The MIRAX X-ray observatory, the first Brazilian-led astrophysics space mission, is designed to perform an unprecedented wide-field, wide-band hard X-ray (5-200 keV) survey of Galactic X-ray transient sources. In the current configuration, MIRAX will carry a set of four coded-mask telescopes with high spatial resolution Cadmium Zinc Telluride (CZT) detector planes, each one consisting of an array of 64 closely tiled CZT pixelated detectors. Taken together, the four telescopes will have a total detection area of 959 cm^2, a large field of view (60x60 degrees FWHM), high angular resolution for this energy range (6 arcmin) and very good spectral resolution (~2 keV @ 60 keV). A stratospheric balloon-borne prototype of one of the MIRAX telescopes has been developed, tested and flown by the Harvard-Smithsonian Center for Astrophysics (CfA) as part of the ProtoEXIST program. In this paper we show results of validation and calibration tests with individual CZT detectors of the ProtoEXIST second generation experiment ...

  19. 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.

  20. Modelling of the small pixel effect in gallium arsenide X-ray imaging detectors

    CERN Document Server

    Sellin, P J

    1999-01-01

    A Monte Carlo simulation has been carried out to investigate the small pixel effect in highly pixellated X-ray imaging detectors fabricated from semi-insulating gallium arsenide. The presence of highly non-uniform weighting fields in detectors with a small pixel geometry causes the majority of the induced signal to be generated when the moving charges are close to the pixellated contacts. The response of GaAs X-ray imaging detectors is further complicated by the presence of charge trapping, particularly of electrons. In this work detectors are modelled with a pixel pitch of 40 and 150 mu m, and with thicknesses of 300 and 500 mu m. Pulses induced in devices with 40 mu m pixels are due almost totally to the movement of the lightly-trapped holes and can exhibit significantly higher charge collection efficiencies than detectors with large electrodes, in which electron trapping is significant. Details of the charge collection efficiencies as a function of interaction depth in the detector and of the incident phot...

  1. An evaluation of semiconductor and ionization chamber detectors for diagnostic x-ray dosimetry measurements.

    Science.gov (United States)

    Martin, C J

    2007-08-07

    Dosemeters for performance testing of x-ray equipment may utilize semiconductor technology or ionization chambers (ICs). Semiconductor dosemeters incorporate several elements into the detectors from which compensation for variations in response with photon energy is derived. The design of the detectors influences their response with angle and this is different from that of ICs. The responses of semiconductor detectors (SDs) and ICs to x-ray beams with a variety of radiation qualities have been measured in order to assess differences in response. Measurements have been made with experimental arrangements simulating use of the detectors in performance testing of digital radiography and fluoroscopy equipment. Results show that differences in photon energy responses between the detectors are small, but because ICs are sensitive to radiation incident from all angles, they record more scattered radiation than SDs. Implications of differences in detector responses are discussed and recommendations made about their use. SDs are more appropriate for measurements of image receptor doses and are recommended for setting up automatic exposure control devices for digital radiography. ICs are suitable for assessment of patient entrance surface dose rate measurements. Correction factors that could be applied to allow comparisons between measurements with different dosemeters are proposed.

  2. Comparison of CCD, CMOS and Hybrid Pixel x-ray detectors: detection principle and data quality

    Science.gov (United States)

    Allé, P.; Wenger, E.; Dahaoui, S.; Schaniel, D.; Lecomte, C.

    2016-06-01

    We compare, from a crystallographic point of view, the data quality obtained using laboratory x-ray diffractometers equipped with a Molybdenum micro-source using different detector types: CCD, CMOS and XPAD hybrid pixel. First we give an overview of the working principle of these different detector types with a focus on their principal differences and their impact on the data quality. Then, using the example of an organic crystal, a comparison between the detector systems concerning the raw data statistics, the refinement agreement factors, the deformation electron density maps, and the residual density after multipolar refinement is presented. It is found that the data quality obtained with the XPAD detector is the best, even though the detection efficiency at the Mo energy (17.5 keV) is only 37% due to the Si-sensor layer thickness of 300 μm. Finally, we discuss the latest x-ray detector developments with an emphasis on the sensor material, where replacing Si by another material such as GaAs would yield detection efficiencies close to 100%, up to energies of 40 keV for hybrid pixel detectors.

  3. X-ray Shield for High Energy Gamma Spectrometry using a n-type HPGe Detector

    Energy Technology Data Exchange (ETDEWEB)

    Byun, Jong In; Yun, Ju Yong [University of Science and Technology, Daejeon (Korea, Republic of); Row, Jeong Hwan; Lee, Ji Yun [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2009-04-15

    In the last several decades HPGe detectors have been used popularly because of good energy resolution and high efficiency. And HPGe detectors to measure low energy gamma rays also have been developed by several companies. The detectors are generally called as a n-type HPGe detector or LEGe. The commercial n-type HPGe detectors have the front window made from carbonate or beryllium to increase the detection efficiency for low energy photons. For that reason, cascade coincidence summing effects by X- and Gamma rays can be produced. In order to use the n-type HPGe detector for high energy gamma rays, therefore, we should eliminate incidence of X-rays or correct the effects. The correction for X- and Gamma rays might be so complicate and difficult. On the other hand, the summing effects can be terminated by additional X-ray shields at the end cap. In this study, we optimized the thickness of shielding material selected for the purpose. This paper demonstrates the optimization process and the shield' s applicability for detection efficiency calibration and radioactivity analysis.

  4. Design and development of hard x-ray imaging detector using scintillator and Si photomultiplier

    Science.gov (United States)

    Goyal, S. K.; Naik, Amisha P.; Mithun, N. P. S.; Vadawale, S. V.; Acharya, Y. B.; Patel, A. R.; Ladiya, T.; Devashrayee, Niranjan M.

    2016-07-01

    There are various astrophysical phenomena which are of great importance and interest such as stellar explosions, Gamma ray bursts etc. There is also a growing interest in exploring the celestial sources in hard X-rays. High sensitive instruments are essential to perform the detailed studies of these cosmic accelerators and explosions. Hard X-ray imaging detectors having high absorption efficiency and mm spatial resolution are the key requirements to locate the generation of these astrophysical phenomenon. We hereby present a detector module which consists of a single CsI scintillation detector of size 15 x 15 x 3 mm3. The photon readout is done using an array of Silicon Photomultipliers (SiPMs). SiPM is a new development in the field of photon detection and can be described as 2D array of small (hundreds of μm2) avalanche photodiodes. We have achieved a spatial resolution of 0.5 mm with our initial setup. By using the array of these detector modules, we can build the detector with a large sensitive area with a very high spatial resolution. This paper presents the experimental details for single detector module using CsI (Tl) scintillator and SiPM and also presents the preliminary results of energy and position measurement. The GEANT4 simulation has also been carried out for the same geometry.

  5. First examination of CASCADE-X-ray-detector and measurement of neutron-mirrorneutron-oscillation; Erste Untersuchungen zum CASCADE-Roentgendetektor und Messung zur Neutron-Spiegelneutron-Oszillation

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, B.

    2007-02-07

    The detection of X-radiation is of utmost importance for both fundamental physics and medical diagnostics. This work investigates whether or not the CASCADE detector working principle, first developed for the detection of neutrons, can be adapted for the detection of X-rays. This modular detector concept combines the use of a solid neutron or X-ray converter with the advantages of a counting gas detector. Thus, it gives the possibility to optimize efficiency, dynamics and spatial resolution independently. Firstly, it is necessary to find a suitable converter material that allows for the best possible detector efficiency. In order to do so, a mathematical model of the complete detector system was developed that yields the total efficiency for any given material. Respecting technical constraints, gold and gadolinium showed to be favorable choices. Based on these theoretical considerations a prototype of a CASCADE X-ray detector was built, and measurements for the determination of this detector's efficiency were conducted. In the second part of this work a CASCADE neutron detector was used to conduct the first measurement the neutron-mirrorneutron oscillation time. Mirrormatter was proposed in 1956 by Lee and Yang to allow for symmetry in the description of the universe despite the existence of parity violation. By using neutrons it was possible to determine a lower limit for the oscillation time in this work. (orig.)

  6. High Dynamic Range X-ray Detector Pixel Architectures Utilizing Charge Removal

    CERN Document Server

    Weiss, Joel T; Philipp, Hugh T; Becker, Julian; Chamberlain, Darol; Purohit, Prafull; Tate, Mark W; Gruner, Sol M

    2016-01-01

    Several charge integrating CMOS pixel front-ends utilizing charge removal techniques have been fabricated to extend dynamic range for x-ray diffraction applications at synchrotron sources and x-ray free electron lasers (XFELs). The pixels described herein build on the Mixed Mode Pixel Array Detector (MM-PAD) framework, developed previously by our group to perform high dynamic range imaging. These new pixels boast several orders of magnitude improvement in maximum flux over the MM-PAD, which is capable of measuring a sustained flux in excess of 10$^{8}$ x-rays/pixel/second while maintaining sensitivity to smaller signals, down to single x-rays. To extend dynamic range, charge is removed from the integration node of the front-end amplifier without interrupting integration. The number of times this process occurs is recorded by a digital counter in the pixel. The parameter limiting full well is thereby shifted from the size of an integration capacitor to the depth of a digital counter. The result is similar to t...

  7. Hohlraum Target Alignment from X-ray Detector Images using Starburst Design Patterns

    Energy Technology Data Exchange (ETDEWEB)

    Leach, R R; Conder, A; Edwards, O; Kroll, J; Kozioziemski, B; Mapoles, E; McGuigan, D; Wilhelmsen, K

    2010-12-14

    National Ignition Facility (NIF) is a high-energy laser facility comprised of 192 laser beams focused with enough power and precision on a hydrogen-filled spherical, cryogenic target to initiate a fusion reaction. The target container, or hohlraum, must be accurately aligned to an x-ray imaging system to allow careful monitoring of the frozen fuel layer in the target. To achieve alignment, x-ray images are acquired through starburst-shaped windows cut into opposite sides of the hohlraum. When the hohlraum is in alignment, the starburst pattern pairs match nearly exactly and allow a clear view of the ice layer formation on the edge of the target capsule. During the alignment process, x-ray image analysis is applied to determine the direction and magnitude of adjustment required. X-ray detector and source are moved in concert during the alignment process. The automated pointing alignment system described here is both accurate and efficient. In this paper, we describe the control and associated image processing that enables automation of the starburst pointing alignment.

  8. Dual-exposure technique for extending the dynamic range of x-ray flat panel detectors.

    Science.gov (United States)

    Sisniega, A; Abella, M; Desco, M; Vaquero, J J

    2014-01-20

    This work presents an approach to extend the dynamic range of x-ray flat panel detectors by combining two acquisitions of the same sample taken with two different x-ray photon flux levels and the same beam spectral configuration. In order to combine both datasets, the response of detector pixels was modelled in terms of mean and variance using a linear model. The model was extended to take into account the effect of pixel saturation. We estimated a joint probability density function (j-pdf) of the pixel values by assuming that each dataset follows an independent Gaussian distribution. This j-pdf was used for estimating the final pixel value of the high-dynamic-range dataset using a maximum likelihood method. The suitability of the pixel model for the representation of the detector signal was assessed using experimental data from a small-animal cone-beam micro-CT scanner equipped with a flat panel detector. The potential extension in dynamic range offered by our method was investigated for generic flat panel detectors using analytical expressions and simulations. The performance of the proposed dual-exposure approach in realistic imaging environments was compared with that of a regular single-exposure technique using experimental data from two different phantoms. Image quality was assessed in terms of signal-to-noise ratio, contrast, and analysis of profiles drawn on the images. The dynamic range, measured as the ratio between the exposure for saturation and the exposure equivalent to instrumentation noise, was increased from 76.9 to 166.7 when using our method. Dual-exposure results showed higher contrast-to-noise ratio and contrast resolution than the single-exposure acquisitions for the same x-ray dose. In addition, image artifacts were reduced in the combined dataset. This technique to extend the dynamic range of the detector without increasing the dose is particularly suited to image samples that contain both low and high attenuation regions.

  9. Computer simulation of the CSPAD, ePix10k, and RayonixMX170HS X-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Tina, Adrienne

    2015-08-21

    The invention of free-electron lasers (FELs) has opened a door to an entirely new level of scientific research. The Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory is an X-ray FEL that houses several instruments, each with its own unique X-ray applications. This light source is revolutionary in that while its properties allow for a whole new range of scientific opportunities, it also poses numerous challenges. For example, the intensity of a focused X-ray beam is enough to damage a sample in one mere pulse; however, the pulse speed and extreme brightness of the source together are enough to obtain enough information about that sample, so that no further measurements are necessary. An important device in the radiation detection process, particularly for X-ray imaging, is the detector. The power of the LCLS X-rays has instigated a need for better performing detectors. The research conducted for this project consisted of the study of X-ray detectors to imitate their behaviors in a computer program. The analysis of the Rayonix MX170-HS, CSPAD, and ePix10k in particular helped to understand their properties. This program simulated the interaction of X-ray photons with these detectors to discern the patterns of their responses. A scientist’s selection process of a detector for a specific experiment is simplified from the characterization of the detectors in the program.

  10. Organic semiconducting single crystals as next generation of low-cost, room-temperature electrical X-ray detectors.

    Science.gov (United States)

    Fraboni, Beatrice; Ciavatti, Andrea; Merlo, Francesco; Pasquini, Luca; Cavallini, Anna; Quaranta, Alberto; Bonfiglio, Annalisa; Fraleoni-Morgera, Alessandro

    2012-05-02

    Direct, solid-state X-ray detectors based on organic single crystals are shown to operate at room temperature, in air, and at voltages as low as a few volts, delivering a stable and reproducible linear response to increasing X-ray dose rates, with notable radiation hardness and resistance to aging. All-organic and optically transparent devices are reported.

  11. HEAO 1 A-2 low-energy detector X-ray spectra of the Cygnus Loop

    Science.gov (United States)

    Leahy, D. A.; Fink, R.; Nousek, J.

    1990-01-01

    The Cygnus Loop supernova remnant was observed by the A-2 low-energy detector (LED) proportional counters on the HEAO 1 satellite. Recent improvements to the non-X-ray background rejection and detector response simulation have allowed production of the most accurate spectra of the Cygnus Loop to date. Three separate regions of the Cygnus Loop were observed. Single-temperature, Raymond-Smith models are inadequate to describe the spectra, but two component model fits are good. Temperature, column density, and emission measure variations across the Cygnus Loop are found. These results are interpreted and compared with previous work.

  12. Compton polarimeter as a focal plane detector for hard X-ray telescope: sensitivity estimation with Geant4 simulations

    Science.gov (United States)

    Chattopadhyay, T.; Vadawale, S. V.; Pendharkar, J.

    2013-04-01

    X-ray polarimetry can be an important tool for investigating various physical processes as well as their geometries at the celestial X-ray sources. However, X-ray polarimetry has not progressed much compared to the spectroscopy, timing and imaging mainly due to the extremely photon-hungry nature of X-ray polarimetry leading to severely limited sensitivity of X-ray polarimeters. The great improvement in sensitivity in spectroscopy and imaging was possible due to focusing X-ray optics which is effective only at the soft X-ray energy range. Similar improvement in sensitivity of polarisation measurement at soft X-ray range is expected in near future with the advent of GEM based photoelectric polarimeters. However, at energies >10 keV, even spectroscopic and imaging sensitivities of X-ray detector are limited due to lack of focusing optics. Thus hard X-ray polarimetry so far has been largely unexplored area. On the other hand, typically the polarisation degree is expected to increase at higher energies as the radiation from non-thermal processes is dominant fraction. So polarisation measurement in hard X-ray can yield significant insights into such processes. With the recent availability of hard X-ray optics (e.g. with upcoming NuSTAR, Astro-H missions) which can focus X-rays from 5 KeV to 80 KeV, sensitivity of X-ray detectors in hard X-ray range is expected to improve significantly. In this context we explore feasibility of a focal plane hard X-ray polarimeter based on Compton scattering having a thin plastic scatterer surrounded by cylindrical array scintillator detectors. We have carried out detailed Geant4 simulation to estimate the modulation factor for 100 % polarized beam as well as polarimetric efficiency of this configuration. We have also validated these results with a semi-analytical approach. Here we present the initial results of polarisation sensitivities of such focal plane Compton polarimeter coupled with the reflection efficiency of present era hard X-ray

  13. Possible use of CdTe detectors in kVp monitoring of diagnostic x-ray tubes

    OpenAIRE

    Krmar, M.; Bucalović, N.; Baucal, M.; Jovančević, N.

    2010-01-01

    It has been suggested that kVp of diagnostic X-ray devices (or maximal energy of x-ray photon spectra) should be monitored routinely; however a standardized noninvasive technique has yet to be developed and proposed. It is well known that the integral number of Compton scattered photons and the intensities of fluorescent x-ray lines registered after irradiation of some material by an x-ray beam are a function of the maximal beam energy. CdTe detectors have sufficient energy resolution to dist...

  14. Time-resolved and position-resolved X-ray spectrometry with a pixelated detector

    Energy Technology Data Exchange (ETDEWEB)

    Sievers, Peter

    2012-12-07

    The aim of the work presented here was to measure X-ray spectra with a pixelated detector. Due to effects in the sensor the spectrum cannot be measured directly and has to be calculated by a deconvolution of the measured data. In the scope of this work the deconvolution of the measured spectra could be enhanced considerably by - amongst other things - the introduction of the Bayesian deconvolution method. Those improvements opened the possibilities for further measurements. For the measurements the detectors of the Medipix family have been used. They are nowadays used for a wide range of applications and scientific research. Their main advantage is the very high position resolution gained by a pixel pitch of 55 μm and a high number of 65536 pixels. The Timepix detector has, in particular, two special possibilities of measurement: the ToA mode and the ToT mode. In ToA mode the arrival time of an impinging photon is measured and in ToT mode the amount of deposited charge is measured. The most common method of operation is counting the number of impinging photons that release a charge higher than a preset threshold in each pixel. As this released charge is proportional to the energy deposition of the impinging photon, one can perform energy-sensitive measurements. To perform the deconvolution of the measured energy distribution there is a need of an energy response matrix describing the detector response on radiation. For some detectors it is possible to obtain an analytic model of the response functions. Due to the high discrepancy between the impinging spectrum and the measured spectrum in case of detectors of the Medipix family, there is so far no analytic model. Thus, the detector response has to be simulated. As I could improve the precision of the measurement quite extensively, I also intended to tune the simulation with more accurate and appropriate models to gain the same level of accuracy. The results of measurement and simulation have then been compared and

  15. Spectrum reconstruction method based on the detector response model calibrated by x-ray fluorescence

    Science.gov (United States)

    Li, Ruizhe; Li, Liang; Chen, Zhiqiang

    2017-02-01

    Accurate estimation of distortion-free spectra is important but difficult in various applications, especially for spectral computed tomography. Two key problems must be solved to reconstruct the incident spectrum. One is the acquisition of the detector energy response. It can be calculated by Monte Carlo simulation, which requires detailed modeling of the detector system and a high computational power. It can also be acquired by establishing a parametric response model and be calibrated using monochromatic x-ray sources, such as synchrotron sources or radioactive isotopes. However, these monochromatic sources are difficult to obtain. Inspired by x-ray fluorescence (XRF) spectrum modeling, we propose a feasible method to obtain the detector energy response based on an optimized parametric model for CdZnTe or CdTe detectors. The other key problem is the reconstruction of the incident spectrum with the detector response. Directly obtaining an accurate solution from noisy data is difficult because the reconstruction problem is severely ill-posed. Different from the existing spectrum stripping method, a maximum likelihood-expectation maximization iterative algorithm is developed based on the Poisson noise model of the system. Simulation and experiment results show that our method is effective for spectrum reconstruction and markedly increases the accuracy of XRF spectra compared with the spectrum stripping method. The applicability of the proposed method is discussed, and promising results are presented.

  16. Fast scintillation detectors for high-energy X-ray region

    Science.gov (United States)

    Kishimoto, Shunji; Nishikido, Fumihiko; Haruki, Rie; Shibuya, Kengo; Koshimizu, Masanori

    2012-03-01

    We have developed fast scintillation detectors for nuclear resonant scattering experiments using synchrotron radiation and a nuclear excited level existing in >30 keV. A fast x-ray detector using an organic-inorganic perovskite scintillator of phenethylamine lead bromide (PhE-PbBr4) had a dominant light emission with a fast decay time of 9.9 ns. An x-ray detector equipped with a 0.9-mm-thick PhE-PbBr4 crystal (size: ˜8 × 7 mm2) was used to detect nuclear resonant scattering in 61Ni (the first excited level: 67.41 keV; half-life: 5.3 ns). We could successfully record the decaying gamma rays emitted from 61Ni with a relatively high detection efficiency of 24%. A lead-doped plastic scintillator (NE142, Pb ˜5 wt% doped) had been known to have a faster decay time of 1.7 ns. Following a test of a single NE142 detector, a four-channel NE142 detector was fabricated and successfully applied to the synchrotron-radiation based Mössbauer spectroscopy experiment on 61Ni.

  17. Improvement of the detector resolution in X-ray spectrometry by using the maximum entropy method

    Science.gov (United States)

    Fernández, Jorge E.; Scot, Viviana; Giulio, Eugenio Di; Sabbatucci, Lorenzo

    2015-11-01

    In every X-ray spectroscopy measurement the influence of the detection system causes loss of information. Different mechanisms contribute to form the so-called detector response function (DRF): the detector efficiency, the escape of photons as a consequence of photoelectric or scattering interactions, the spectrum smearing due to the energy resolution, and, in solid states detectors (SSD), the charge collection artifacts. To recover the original spectrum, it is necessary to remove the detector influence by solving the so-called inverse problem. The maximum entropy unfolding technique solves this problem by imposing a set of constraints, taking advantage of the known a priori information and preserving the positive-defined character of the X-ray spectrum. This method has been included in the tool UMESTRAT (Unfolding Maximum Entropy STRATegy), which adopts a semi-automatic strategy to solve the unfolding problem based on a suitable combination of the codes MAXED and GRAVEL, developed at PTB. In the past UMESTRAT proved the capability to resolve characteristic peaks which were revealed as overlapped by a Si SSD, giving good qualitative results. In order to obtain quantitative results, UMESTRAT has been modified to include the additional constraint of the total number of photons of the spectrum, which can be easily determined by inverting the diagonal efficiency matrix. The features of the improved code are illustrated with some examples of unfolding from three commonly used SSD like Si, Ge, and CdTe. The quantitative unfolding can be considered as a software improvement of the detector resolution.

  18. Improvement of an X-ray imaging detector based on a scintillating guides screen

    CERN Document Server

    Badel, X; Linnros, J; Kleimann, P; Froejdh, C; Petersson, C S

    2002-01-01

    An X-ray imaging detector has been developed for dental applications. The principle of this detector is based on application of a silicon charge coupled device covered by a scintillating wave-guide screen. Previous studies of such a detector showed promising results concerning the spatial resolution but low performance in terms of signal to noise ratio (SNR) and sensitivity. Recent results confirm the wave-guiding properties of the matrix and show improvement of the detector in terms of response uniformity, sensitivity and SNR. The present study is focussed on the fabrication of the scintillating screen where the principal idea is to fill a matrix of Si pores with a CsI scintillator. The photoluminescence technique was used to prove the wave-guiding property of the matrix and to inspect the filling uniformity of the pores. The final detector was characterized by X-ray evaluation in terms of spatial resolution, light output and SNR. A sensor with a spatial resolution of 9 LP/mm and a SNR over 50 has been achie...

  19. FOXSI: Properties of optics and detectors for hard-X rays

    Science.gov (United States)

    Camilo Buitrago-Casas, Juan; Glesener, Lindsay; Christe, Steven; Krucker, Sam; Ishikawa, Shin-nosuke; Foster, Natalie

    2015-04-01

    The Focusing Optics X-ray Solar Imager (FOXSI) is a state-of-the-art direct focusing X-ray telescope designed to observe the Sun. This experiment completed its second flight onboard a sounding rocket last December 11, 2014 from the White Sands Missile Range in New Mexico. The optics use a set of iridium-coated nickel/cobalt mirrors made using a replication technique based on an electroformed perfect polished surface. Since this technique creates full shells that no need to be co-aligned with other segments, an angular resolution of up to ~5 arcsec is gotten. The FOXSI focal plane consists of seven double-sided strip detectors. Five Silicon and 2 CdTe detectors were used during the second flight.We present on various properties of Wolter-I optics that are applicable to solar HXR observation, including ray-tracing simulations of the single-bounce (“ghost ray”) patterns from sources outside the field of view and angular resolution for different source angles and effective area measurements of the FOXSI optics. We also present the detectors calibration results, paying attention to energy resolution (~0.5 keV), energy thresholds (~4-15 keV for Silicon and ~4-20 keV for CdTe detectors), and spatial coherence of these values over the entire detector.

  20. Development of a TES-Based Anti-Coincidence Detector for Future X-Ray Observations

    Science.gov (United States)

    Bailey, Catherine N.; Adams, J. S.; Bandler, S. R.; Eckart, M. E.; Ewin, A. J.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Sadleir, J. E.; Smith, S. J.; Sultana, M.

    2012-01-01

    Microcalorimeters onboard future x-ray observatories require an anticoincidence detector to remove environmental backgrounds. In order to most effectively integrate this anti-coincidence detector with the main microcalorimeter array, both instruments should use similar read-out technology. The detectors used in the Cryogenic Dark Matter Search (CDMS) use a phonon measurement technique that is well suited for an anti-coincidence detector with a microcalorimeter array using SQUID readout. This technique works by using a transition-edge sensor (TES) connected to superconducting collection fins to measure the athermal phonon signal produced when an event occurs in the substrate crystal. Energy from the event propagates through the crystal to the superconducting collection fins, creating quasiparticles, which are then trapped as they enter the TES where they produce a signal. We are currently developing a prototype anti-coincidence detector for future x-ray missions and have recently fabricated test devices with Mo/Au TESs and Al collection fins. We present results from the first tests of these devices which indicate a proof of concept that quasiparticle trapping is occurring in these materials.

  1. Modeling of photocurrent and lag signals in amorphous selenium x-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Siddiquee, Sinchita; Kabir, M. Z., E-mail: kabir@encs.concordia.ca [Department of Electrical and Computer Engineering, Concordia University, 1455 Blvd. de Maisonneuve West, Montreal, Quebec H3G 1M8 (Canada)

    2015-07-15

    A mathematical model for transient photocurrent and lag signal in x-ray imaging detectors has been developed by considering charge carrier trapping and detrapping in the energy distributed defect states under exponentially distributed carrier generation across the photoconductor. The model for the transient and steady-state carrier distributions and hence the photocurrent has been developed by solving the carrier continuity equation for both holes and electrons. The residual (commonly known as lag signal) current is modeled by solving the trapping rate equations considering the thermal release and trap filling effects. The model is applied to amorphous selenium (a-Se) detectors for both chest radiography and mammography. The authors analyze the dependence of the residual current on various factors, such as x-ray exposure, applied electric field, and temperature. The electron trapping and detrapping mostly determines the residual current in a-Se detectors. The lag signal is more prominent in chest radiographic detector than in mammographic detectors. The model calculations are compared with the published experimental data and show a very good agreement.

  2. A double area detector system for simultaneous small and wide-angle X-ray scattering

    CERN Document Server

    Pokric, B; Ryan, A J; Fairclough, P; Dobson, B R; Derbyshire, G E; Helsby, W; Long, G; Moon, K

    2002-01-01

    A novel area detector has been designed for material science SR studies, capable of simultaneously collecting the diffraction data in two angular regimes. The detector for collecting wide-angle X-ray scattering (WAXS) data consists of four taper-coupled CCDs arranged as a 2x2 mosaic with a central aperture about 40 mm in diameter, so permitting the inclusion of a distant on-axis CCD detector for small-angle X-ray scattering (SAXS). The distance of the SAXS detector from the sample can be varied over the range 0.27 m to about 2 m. The overall aperture of WAXS detector is approximately 200x200 mm sup 2 allowing the measurement of the diffraction patterns from 5 deg. to 45 deg. with an average angular resolution of 0.05 deg. The parallax error for large angles is substantially reduced as the individual WAXS CCDs are tilted towards the specimen location. Both WAXS and SAXS diffraction data are simultaneously collected at 30 MB/s data rate, which is equivalent to 6 complete frames per second. Each pixel value is d...

  3. A digital X-ray imaging system based on silicon strip detectors working in edge-on configuration

    Energy Technology Data Exchange (ETDEWEB)

    Bolanos, L. [CEADEN, Calle 30 502 e/ 5ta y 7ma Avenida, Playa, Ciudad Habana (Cuba); Boscardin, M. [IRST, Fondazione Bruno Kessler, Via Sommarive 18, Povo, 38100 Trento (Italy); Cabal, A.E. [CEADEN, Calle 30 502 e/ 5ta y 7ma Avenida, Playa, Ciudad Habana (Cuba); Diaz, M. [InSTEC, Ave. Salvador Allende esq. Luaces, Quinta de los Molinos, Ciudad Habana (Cuba); Grybos, P.; Maj, P. [Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, Department of Measurement and Instrumentation, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland); Prino, F. [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Via P. Giuria 1, 10125 Torino (Italy); Ramello, L. [Dipartimento di Scienze e Tecnologie Avanzate, Universita del Piemonte Orientale, Via T. Michel 11, 15100 Alessandria (Italy)], E-mail: luciano.ramello@mfn.unipmn.it; Szczygiel, R. [Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, Department of Measurement and Instrumentation, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland)

    2009-09-21

    We present the energy resolution and imaging performance of a digital X-ray imaging system based on a 512-strip silicon strip detector (SSD) working in the edge-on configuration. The SSDs tested in the system are 300 {mu}m thick with 1 or 2-cm-long strips and 100 {mu}m pitch. To ensure a very small dead area of the SSD working in edge-on configuration, the detector is cut perpendicular to the strips at a distance of only 20 {mu}m from the end of the strips. The 512-strip silicon detector is read out by eight 64-channel integrated circuits called DEDIX [Grybos et al., IEEE Trans. Nucl. Sci. NS-54 (2007) 1207]. The DEDIX IC operates in a single photon counting mode with two independent amplitude discriminators per channel. The readout electronic channel connected to a detector with effective input capacitance of about 2 pF has an average equivalent noise charge (ENC) of about 163 el. rms and is able to count 1 Mcps of average rate of input pulses. The system consisting of 512 channels has an excellent channel-to-channel uniformity-the effective threshold spread calculated to the charge-sensitive amplifier inputs is 12 el. rms (at one sigma level). With this system a few test images of a phantom have been taken in the 10-30 keV energy range.

  4. Serial data acquisition for the X-ray plasma diagnostics with selected GEM detector structures

    Science.gov (United States)

    Czarski, T.; Chernyshova, M.; Pozniak, K. T.; Kasprowicz, G.; Zabolotny, W.; Kolasinski, P.; Krawczyk, R.; Wojenski, A.; Zienkiewicz, P.

    2015-10-01

    The measurement system based on GEM—Gas Electron Multiplier detector is developed for X-ray diagnostics of magnetic confinement tokamak plasmas. The paper is focused on the measurement subject and describes the fundamental data processing to obtain reliable characteristics (histograms) useful for physicists. The required data processing have two steps: 1—processing in the time domain, i.e. events selections for bunches of coinciding clusters, 2—processing in the planar space domain, i.e. cluster identification for the given detector structure. So, it is the software part of the project between the electronic hardware and physics applications. The whole project is original and it was developed by the paper authors. The previous version based on 1-D GEM detector was applied for the high-resolution X-ray crystal spectrometer KX1 in the JET tokamak. The current version considers 2-D detector structures for the new data acquisition system. The fast and accurate mode of data acquisition implemented in the hardware in real time can be applied for the dynamic plasma diagnostics. Several detector structures with single-pixel sensors and multi-pixel (directional) sensors are considered for two-dimensional X-ray imaging. Final data processing is presented by histograms for selected range of position, time interval and cluster charge values. Exemplary radiation source properties are measured by the basic cumulative characteristics: the cluster position distribution and cluster charge value distribution corresponding to the energy spectra. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics

  5. Design and performance of a 2-D multi-wire position sensitive X-ray detector

    Indian Academy of Sciences (India)

    S S Desai; J N Joshi; A M Shaikh

    2002-10-01

    A 2-D multi-wire position sensitive detector for X-ray diffraction and small angle X-ray scattering studies is described. The detector has an active area of 100 mm × 100 mm and consists of an anode plane with 10 m SS wires at 3 mm spacing and a pair of orthogonal cathode readout planes with 25 m SS wires placed at 1.5 mm spacing. The position information is obtained using charge division method and recorded using a laboratory built data acquisition system. The resolution and gas gain was measured for 5.9 keV X-rays (55Fe-source) as a function of the anode wire voltage and gas pressure. It was observed that the proportional region of the PSD at 100 kPa pressure extended up to a high voltage value of around 1.5 kV and it shifted to high values up to 2 kV for gas pressure of 300 kPa. The energy resolution improved from 18% (FWHM) to 12% with increase in pressure. The spatial resolution of the PSD also showed improvement, with a value of 1.2 mm × 1.4 mm at 300 kPa gas pressure. A maximum gain of 5 × 104 is obtained.

  6. 3D Medipix2 detector characterization with a micro-focused X-ray beam

    Science.gov (United States)

    Gimenez, E. N.; Maneuski, D.; Mac Raighne, A.; Parkes, C.; Bates, R.; O'Shea, V.; Fleta, C.; Pellegrini, G.; Lozano, M.; Alianelli, L.; Sawhney, K. J. S.; Marchal, J.; Tartoni, N.

    2011-05-01

    Three-dimensional (3D) photodiode detectors offer advantages over standard planar photodiodes in a wide range of applications. The main advantage of these sensors for X-ray imaging is their reduced charge sharing between adjacent pixels, which could improve spatial and spectral resolution. However, a drawback of 3D sensors structures is the loss of detection efficiency due to the presence in the pixel structure of heavily doped electrode columns which are insensitive to X-ray. In this work two types of 3D silicon detectors: n-type wafer with hole collecting readout-columns (N-TYPE) and p-type wafer with electron collecting readout-columns (P-TYPE), bump-bounded to a Medipix2 read-out chip were characterized with a 14.5 keV micro-focused X-ray beam from a synchrotron. Measurements of the detection efficiency and the charge sharing were performed at different bias voltages and Medipix2 energy thresholds and compared with those of a standard planar silicon sensor.

  7. X-ray spectroscopy with a multi-anode sawtooth silicon drift detector the diffusion process

    CERN Document Server

    Sonsky, J; Sarro, P M; Eijk, C W

    2002-01-01

    The position sensitive detection of low-energy X-rays can be realized by means of a multi-anode linear silicon drift detector (SDD). However, a severe worsening of the spectroscopic quality of the detector is observed due to the lateral broadening of the X-ray generated electron cloud during drift. Recently, we have proved experimentally that electron confinement can be achieved by means of sawtooth-shaped p sup + strips; the sawtooth concept. This paper will present room temperature X-ray spectroscopy measurements clearly demonstrating the improvement of spectroscopic quality of the sawtooth SDD as compared with a traditional linear SDD. Using a sawtooth SDD we have measured an energy resolution of 1.4 keV FWHM at the 13.9 keV peak of sup 2 sup 4 sup 1 Am at room temperature and a substantial reduction of the number of split events is also observed. The calculation of the influence of diffusion on the quality of the pulse height spectrum will also be given.

  8. Alternative Optimizations of X-ray TES Arrays: Soft X-rays, High Count Rates, and Mixed-Pixel Arrays

    Science.gov (United States)

    Kilbourne, C. A.; Bandler, S. R.; Brown, A.-D.; Chervenak, J. A.; Figueroa-Feliciano, E.; Finkbeiner, F. M.; Iyomoto, N.; Kelley, R. L.; Porter, F. S.; Smith, S. J.

    2007-01-01

    We are developing arrays of superconducting transition-edge sensors (TES) for imaging spectroscopy telescopes such as the XMS on Constellation-X. While our primary focus has been on arrays that meet the XMS requirements (of which, foremost, is an energy resolution of 2.5 eV at 6 keV and a bandpass from approx. 0.3 keV to 12 keV), we have also investigated other optimizations that might be used to extend the XMS capabilities. In one of these optimizations, improved resolution below 1 keV is achieved by reducing the heat capacity. Such pixels can be based on our XMS-style TES's with the separate absorbers omitted. These pixels can added to an array with broadband response either as a separate array or interspersed, depending on other factors that include telescope design and science requirements. In one version of this approach, we have designed and fabricated a composite array of low-energy and broad-band pixels to provide high spectral resolving power over a broader energy bandpass than could be obtained with a single TES design. The array consists of alternating pixels with and without overhanging absorbers. To explore optimizations for higher count rates, we are also optimizing the design and operating temperature of pixels that are coupled to a solid substrate. We will present the performance of these variations and discuss other optimizations that could be used to enhance the XMS or enable other astrophysics experiments.

  9. Investigation of chemical vapour deposition diamond detectors by X- ray micro-beam induced current and X-ray micro-beam induced luminescence techniques

    CERN Document Server

    Olivero, P; Vittone, E; Fizzotti, F; Paolini, C; Lo Giudice, A; Barrett, R; Tucoulou, R

    2004-01-01

    Tracking detectors have become an important ingredient in high-energy physics experiments. In order to survive the harsh detection environment of the Large Hadron Collider (LHC), trackers need to have special properties. They must be radiation hard, provide fast collection of charge, be as thin as possible and remove heat from readout electronics. The unique properties of diamond allow it to fulfill these requirements. In this work we present an investigation of the charge transport and luminescence properties of "detector grade" artificial chemical vapour deposition (CVD) diamond devices developed within the CERN RD42 collaboration, performed by means of X-ray micro-beam induced current collection (XBICC) and X-ray micro- beam induced luminescence (XBIL) techniques. XBICC technique allows quantitative estimates of the transport parameters of the material to be evaluated and mapped with micrometric spatial resolution. In particular, the high resolution and sensitivity of the technique has allowed a quantitati...

  10. Development of TES-based detectors array for the X-ray Integral Field Unit (X-IFU) on the future x-ray observatory ATHENA

    CERN Document Server

    Gottardi, Luciano; Barret, Didier; Bruijn, Marcel P; Hartog, Roland H den; Herder, Jan-Willem den; Hoevers, Henk F C; Kiviranta, Mikko; van der Kuur, Jan; van der Linden, Anton J; Jackson, Brian D; Jambunathan, Madu; Ridder, Marcel L

    2016-01-01

    We are developing transition-edge sensor (TES)-based microcalorimeters for the X-ray Integral Field Unit (XIFU) of the future European X-Ray Observatory Athena. The microcalorimeters are based on TiAu TESs coupled to 250{\\mu}m squared, AuBi absorbers. We designed and fabricated devices with different contact geometries between the absorber and the TES to optimise the detector performance and with different wiring topology to mitigate the self-magnetic field. The design is tailored to optimise the performance under Frequency Domain Multiplexing. In this paper we review the main design feature of the pixels array and we report on the performance of the 18 channels, 2-5MHz frequency domain multiplexer that will be used to characterised the detector array.

  11. Characterizing X-ray detectors for prototype digital breast tomosynthesis systems

    Science.gov (United States)

    Kim, Y.-s.; Park, H.-s.; Park, S.-J.; Choi, S.; Lee, H.; Lee, D.; Choi, Y.-W.; Kim, H.-J.

    2016-03-01

    The digital breast tomosynthesis (DBT) system is a newly developed 3-D imaging technique that overcomes the tissue superposition problems of conventional mammography. Therefore, it produces fewer false positives. In DBT system, several parameters are involved in image acquisition, including geometric components. A series of projections should be acquired at low exposure. This makes the system strongly dependent on the detector's characteristic performance. This study compares two types of x-ray detectors developed by the Korea Electrotechnology Research Institute (KERI). The first prototype DBT system has a CsI (Tl) scintillator/CMOS based flat panel digital detector (2923 MAM, Dexela Ltd.), with a pixel size of 0.0748 mm. The second uses a-Se based direct conversion full field detector (AXS 2430, analogic) with a pixel size of 0.085 mm. The geometry of both systems is same, with a focal spot 665.8 mm from the detector, and a center of rotation 33 mm above the detector surface. The systems were compared with regard to modulation transfer function (MTF), normalized noise power spectrum (NNPS), detective quantum efficiency (DQE) and a new metric, the relative object detectability (ROD). The ROD quantifies the relative performance of each detector at detecting specified objects. The system response function demonstrated excellent linearity (R2>0.99). The CMOS-based detector had a high sensitivity, while the Anrad detector had a large dynamic range. The higher MTF and noise power spectrum (NPS) values were measured using an Anrad detector. The maximum DQE value of the Dexela detector was higher than that of the Anrad detector with a low exposure level, considering one projection exposure for tomosynthesis. Overall, the Dexela detector performed better than did the Anrad detector with regard to the simulated Al wires, spheres, test objects of ROD with low exposure level. In this study, we compared the newly developed prototype DBT system with two different types of x-ray

  12. Promising X-ray fluorescent tests for superconducting tunnel junction detector

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Stephan; Robinson, Art

    2001-01-11

    Scientists in the Physical Biosciences Division of the Ernest Orlando Berkeley National Laboratory (Berkeley Lab) studying transition metals in proteins with fluorescence-detected L-edge absorption spectroscopy have found the measurements to be extremely challenging. The difficulty is that the metal centers are present in very dilute concentrations so that their weak fluorescence is often obscured by strong background signals from carbon and oxygen. To solve this problem, the Berkeley group has been working with researchers from the Advanced Detector Group at the Lawrence Livermore National Laboratory on an energy-dispersive superconducting tunnel junction x-ray detector. These devices in principle have the energy resolution needed to reveal the metal signal. The most recent results with the latest version of the detector on Beamline 4.0.1-2 at the Advanced Light Source (ALS) illustrate the promise of the cryogenic detector strategy not only for this application but also for spectroscopy of other types of dilute samples.

  13. Uncooled Radiation Hard Large Area SiC X-ray and EUV Detectors and 2D Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project seeks to design, fabricate, characterize and commercialize large area, uncooled and radiative hard 4H-SiC EUV ? soft X-ray detectors capable of ultra...

  14. Possible use of CdTe detectors in kVp monitoring of diagnostic x-ray tubes.

    Science.gov (United States)

    Krmar, M; Bucalović, N; Baucal, M; Jovančević, N

    2010-10-01

    It has been suggested that kVp of diagnostic X-ray devices (or maximal energy of x-ray photon spectra) should be monitored routinely; however a standardized noninvasive technique has yet to be developed and proposed. It is well known that the integral number of Compton scattered photons and the intensities of fluorescent x-ray lines registered after irradiation of some material by an x-ray beam are a function of the maximal beam energy. CdTe detectors have sufficient energy resolution to distinguish individual x-ray fluorescence lines and high efficiency for the photon energies in the diagnostic region. Our initial measurements have demonstrated that the different ratios of the integral number of Compton scattered photons and intensities of K and L fluorescent lines detected by CdTe detector are sensitive function of maximal photon energy and could be successfully applied for kVp monitoring.

  15. The hard X-ray response of a large area HgI sub 2 detector

    CERN Document Server

    Owens, A; Bavdaz, M; Berg, L V D; Peacock, A; Puig, A

    2002-01-01

    We summarise the results of a number of X-ray measurements on a 1.06 cm sup 2 , 0.18 cm thick HgI sub 2 detector carried out at the European Synchrotron Research Facility at Grenoble, France. The detector energy response function was found to be linear over the energy range 8-27 keV with an average rms non-linearity of 0.6%, consistent with statistics. At room temperature, under full area illumination, the FWHM energy resolution was 1.4 keV at 5.9 keV rising to 3.9 keV at 59.54 keV. Under pencil beam illumination, the measured energy resolution at 8 keV was 1.4 keV FWHM at a detector temperature of 9 deg. C. Using a 50x50 mu m sup 2 10 keV monoenergetic X-ray beam, the spatial uniformity of the detector response was determined by a raster scan technique to be at the +-5% level.

  16. Linearity discontinuities in Xe-filled X-ray microstrip detectors

    DEFF Research Database (Denmark)

    Zavattini, G.; Feroci, M.; Budtz-Jørgensen, Carl

    1997-01-01

    A prototype Xe + 10% CH4 microstrip detector was used to study the K-edge discontinuity in the pulse-height distribution as a function of the energy of incident X-rays. The electronics used was such that a pulse-shape rejection could be made of K-fluorescence reabsorption in the detector. The mea......A prototype Xe + 10% CH4 microstrip detector was used to study the K-edge discontinuity in the pulse-height distribution as a function of the energy of incident X-rays. The electronics used was such that a pulse-shape rejection could be made of K-fluorescence reabsorption in the detector....... The measured jump at the K-edge was (169 +/- 12)eV. It was also seen that K-alpha- and K-beta-decay channels produce different pulse heights for the same deposited energy. We find that the difference in energy between the calibration fines of the K-beta 2- and the K-beta 1.3-escape peaks is (93+/-12)eV whereas...... between the K-beta 1.3 and the K-alpha-escape peaks' calibration the energy gal is (69+/-7)eV....

  17. Miniaturized X-ray telescope for VZLUSAT-1 nanosatellite with Timepix detector

    Science.gov (United States)

    Baca, T.; Platkevic, M.; Jakubek, J.; Inneman, A.; Stehlikova, V.; Urban, M.; Nentvich, O.; Blazek, M.; McEntaffer, R.; Daniel, V.

    2016-10-01

    We present the application of a Timepix detector on the VZLUSAT-1 nanosatellite. Timepix is a compact pixel detector (256×256 square pixels, 55×55 μm each) sensitive to hard X-ray radiation. It is suitable for detecting extraterrestrial X-rays due to its low noise characteristics, which enables measuring without special cooling. This project aims to verify the practicality of the detector in conjunction with 1-D Lobster-Eye optics to observe celestial sources between 5 and 20 keV. A modified USB interface (developed by IEAP at CTU in Prague) is used for low-level control of the Timepix. An additional 8-bit Atmel microcontroller is dedicated for commanding the detector and to process the data onboard the satellite. We present software methods for onboard post-processing of captured images, which are suitable for implementation under the constraints of the low-powered embedded hardware. Several measuring modes are prepared for different scenarios including single picture exposure, solar UV-light triggered exposure, and long-term all-sky monitoring. The work has been done within Medipix2 collaboration. The satellite is planned for launch in April 2017 as a part of the QB50 project with an end of life expectancy in 2019.

  18. Linearity discontinuities in Xe-filled X-ray microstrip detectors

    DEFF Research Database (Denmark)

    Zavattini, G.; Feroci, M.; Budtz-Jørgensen, Carl

    1997-01-01

    A prototype Xe + 10% CH4 microstrip detector was used to study the K-edge discontinuity in the pulse-height distribution as a function of the energy of incident X-rays. The electronics used was such that a pulse-shape rejection could be made of K-fluorescence reabsorption in the detector. The mea......A prototype Xe + 10% CH4 microstrip detector was used to study the K-edge discontinuity in the pulse-height distribution as a function of the energy of incident X-rays. The electronics used was such that a pulse-shape rejection could be made of K-fluorescence reabsorption in the detector....... The measured jump at the K-edge was (169 +/- 12)eV. It was also seen that K-alpha- and K-beta-decay channels produce different pulse heights for the same deposited energy. We find that the difference in energy between the calibration fines of the K-beta 2- and the K-beta 1.3-escape peaks is (93+/-12)eV whereas...... between the K-beta 1.3 and the K-alpha-escape peaks' calibration the energy gal is (69+/-7)eV....

  19. Development of CdZnTe X-ray detectors at DSRI

    DEFF Research Database (Denmark)

    van Pamelen, M.A.J.; Budtz-Jørgensen, Carl; Kuvvetli, Irfan

    2000-01-01

    An overview of the development of CdZnTe X-ray detectors at the Danish Space Research Institute is presented. Initiated in the beginning of 1996, the main motivation at that time was to develop focal plane detectors for the novel type of hard X-ray telescopes, which are currently under study at D...... trapping has now little influence and the spectrum displays a pronounced Gaussian peak at 661 keV with a width (FWHM) of 6.9 keV. Also a small peak produced by CdTe escape events can now be observed. At the same time, no events have to be rejected....... at DSRI. With the advent of the Danish Micro Satellite program it was, however, recognised that this type of detector is very well suited for two proposed missions (eXCALIBur, AXO). The research at DSRI has so far been concentrated on the spectroscopic properties of the CZT detector. At DSRI we have...

  20. Recent Developments in Transition-Edge Strip Detectors for Solar X-Rays

    Science.gov (United States)

    Rausch, Adam J.; Deiker, Steven W.; Hilton, Gene; Irwin, Kent D.; Martinez-Galarce, Dennis S.; Shing, Lawrence; Stern, Robert A.; Ullom, Joel N.; Vale, Leila R.

    2008-01-01

    LMSAL and NIST are developing position-sensitive x-ray strip detectors based on Transition Edge Sensor (TES) microcalorimeters optimized for solar physics. By combining high spectral (E/ delta E approximately equals 1600) and temporal (single photon delta t approximately equals 10 micro s) resolutions with imaging capabilities, these devices will be able to study high-temperature (>l0 MK) x-ray lines as never before. Diagnostics from these lines should provide significant new insight into the physics of both microflares and the early stages of flares. Previously, the large size of traditional TESs, along with the heat loads associated with wiring large arrays, presented obstacles to using these cryogenic detectors for solar missions. Implementing strip detector technology at small scales, however, addresses both issues: here, a line of substantially smaller effective pixels requires only two TESs, decreasing both the total array size and the wiring requirements for the same spatial resolution. Early results show energy resolutions of delta E(sub fwhm) approximately equals 30 eV and spatial resolutions of approximately 10-15 micron, suggesting the strip-detector concept is viable.

  1. 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.

  2. Analysis and operation of DePFET X-ray imaging detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lauf, Thomas

    2011-04-28

    The latest active pixel sensor for X-ray imaging spectroscopy developed at the Max-Planck-Halbleiterlabor (HLL) is the Depleted P-channel Field Effect Transistor (DePFET). This detector type unites detector and first stage amplification and has excellent energy resolution, low noise readout at high speed and low power consumption. This is combined with the possibility of random accessibility of pixels and on-demand readout. In addition it possesses all advantages of a sidewards depleted device, i.e. 100% fill factor and very good quantum efficiency. In the course of the development of DePFET detectors the need of a data analysis software for DePFET devices became apparent. A new tool was developed within the scope of this thesis, which should enable scientists to analyze DePFET data, but also be flexible enough so it can be adapted to new device variants and analysis challenges. A modular concept was thus implemented: a base program running an analysis by individual steps encapsulating algorithms, which can be interchanged. The result is a flexible, adaptable, and expandable analysis software. The software was used to investigate and qualify different structural variants of DePFET detectors. Algorithms to examine detector effects and methods to correct them were developed and integrated into the software. This way, a standard analysis suite for DePFET data was built up which is used at the HLL. Beside the planned use as detector for the wide field imager in the space X-ray observatory IXO, DePFET matrices will be used as focal plane array on the Mercury Imaging X-ray Spectrometer on board the Mercury probe BepiColombo which is scheduled for launch in 2014. The developed analysis software was used in the detector development for this mission to qualify test structures, analyze detector effects and study experimental results. In the course of this development, detector prototypes were studied in respect of linearity, charge collection and detection efficiency in an

  3. Signal and noise transfer properties of photoelectric interactions in diagnostic x-ray imaging detectors.

    Science.gov (United States)

    Hajdok, G; Yao, J; Battista, J J; Cunningham, I A

    2006-10-01

    Image quality in diagnostic x-ray imaging is ultimately limited by the statistical properties governing how, and where, x-ray energy is deposited in a detector. This in turn depends on the physics of the underlying x-ray interactions. In the diagnostic energy range (10-100 keV), most of the energy deposited in a detector is through photoelectric interactions. We present a theoretical model of the photoelectric effect that specifically addresses the statistical nature of energy absorption by photoelectrons, K and L characteristic x rays, and Auger electrons. A cascaded-systems approach is used that employs a complex structure of parallel cascades to describe signal and noise transfer through the photoelectric effect in terms of the modulation transfer function, Wiener noise power spectrum, and detective quantum efficiency (DQE). The model was evaluated by comparing results with Monte Carlo calculations for x-ray converters based on amorphous selenium (a-Se) and lead (Pb), representing both low and high-Z materials. When electron transport considerations can be neglected, excellent agreement (within 3%) is obtained for each metric over the entire diagnostic energy range in both a-Se and Pb detectors up to 30 cycles/mm, the highest frequency tested. The cascaded model overstates the DQE when the electron range cannot be ignored. This occurs at approximately two cycles/mm in a-Se at an incident photon energy of 80 keV, whereas in Pb, excellent agreement is obtained for the DQE over the entire diagnostic energy range. However, within the context of mammography (20 keV) and micro-computed tomography (40 keV), the effects of electron transport on the DQE are negligible compared to fluorescence reabsorption, which can lead to decreases of up to 30% and 20% in a-Se and Pb, respectively, at 20 keV; and 10% and 5%, respectively, at 40 keV. It is shown that when Swank noise is identified in a Fourier model, the Swank factor must be frequency dependent. This factor decreases

  4. Application of GaAs and CdTe photoconductor detectors to X-ray flash radiography

    Energy Technology Data Exchange (ETDEWEB)

    Mathy, F.; Cuzin, M.; Gagelin, J.J.; Mermet, R.; Piaget, B.; Rustique, J.; Verger, L. (CEA, Direction des Technologies Avancees, Lab. d' Electronique, de Technologie et d' Instrumentation, DSYS, 38 - Grenoble (France)); Hauducoeur, A.; Nicolas, P.; Le Dain, L.; Hyvernage, M. (CEA, Direction des Applications Militaires, 77 - Courtry (France))

    1992-11-15

    Some insulating GaAs and CdTe:Cl photoconductor probes were qualified on high energy X-ray single-shot flash generators. The estimated minimum detected dose per flash corresponding to a 230 mrad direct beam attenuated by 200 mm lead was 20 [mu]rad. The dynamic range was about 4 decades in amplitude or charge, with a good linearity. Such detectors, by locating the origin of the parasitic scattered beam, could be used to eliminate this parasitic beam in X-ray flash radiography in detonics experiments. Imaging possibilities are mentioned, as well as X-ray generator monitoring with such detectors or with neutron preirradiated photoconductors. (orig.).

  5. Application of GaAs and CdTe photoconductor detectors to x-ray flash radiography

    Energy Technology Data Exchange (ETDEWEB)

    Mathy, F.; Cuzin, M.; Gagelin, J.J.; Mermet, R.; Piaget, B.; Rustique, J.; Verger, L. [CEA Centre d`Etudes de Grenoble, 38 (FR). Direction des Technologies Avancees; Hauducoeur, A.; Nicolas, P.; Le Dain, L.; Hyvernage, M. [CEA Centre d`Etudes de Vaujours, 77 - Courtry (FR)

    1991-12-31

    Semi-insulating GaAs and CdTe:Cl photoconductor probes were qualified on high energy X ray single shot flash generators. The estimated minimum detected dose per flash corresponding to a 230 mrad direct beam attenuated by 200 mm lead was 20 {mu}rad. The dynamic range was about 4 decades in amplitude or charges, with a good linearity. Such detectors, by locating the origin of the parasitic scattered beam, could be used to eliminate this parasitic beam in X ray flash radiography in detonics experiments. Imaging possibilities are mentioned, as well as X ray generator monitoring with such detectors or with neutron preirradiated photoconductors.

  6. The Large Area Detector of LOFT: the Large Observatory for X-ray Timing

    CERN Document Server

    Zane, S; Kennedy, T; Feroci, M; Herder, J -W Den; Ahangarianabhari, M; Argan, A; Azzarello, P; Baldazzi, G; Barbera, M; Barret, D; Bertuccio, G; Bodin, P; Bozzo, E; Bradley, L; Cadoux, F; Cais, P; Campana, R; Coker, J; Cros, A; Del Monte, E; De Rosa, A; Di Cosimo, S; Donnarumma, I; Evangelista, Y; Favre, Y; Feldman, C; Fraser, G; Fuschino, F; Grassi, M; Hailey, M R; Hudec, R; Labanti, C; Macera, D; Malcovati, P; Marisaldi, M; Martindale, A; Mineo, T; Muleri, F; Nowak, M; Orlandini, M; Pacciani, L; Perinati, E; Petracek, V; Pohl, M; Rachevski, A; Smith, P; Santangelo, A; Seyler, J -Y; Schmid, C; Soffitta, P; Suchy, S; Tenzer, C; Uttley, P; Vacchi, A; Zampa, G; Zampa, N; Wilms, J; Winter, B

    2014-01-01

    LOFT (Large Observatory for X-ray Timing) is one of the five candidates that were considered by ESA as an M3 mission (with launch in 2022-2024) and has been studied during an extensive assessment phase. It is specifically designed to perform fast X-ray timing and probe the status of the matter near black holes and neutron stars. Its pointed instrument is the Large Area Detector (LAD), a 10 m 2 -class instrument operating in the 2-30keV range, which holds the capability to revolutionise studies of variability from X-ray sources on the millisecond time scales. The LAD instrument has now completed the assessment phase but was not down-selected for launch. However, during the assessment, most of the trade-offs have been closed leading to a robust and well documented design that will be re- proposed in future ESA calls. In this talk, we will summarize the characteristics of the LAD design and give an overview of the expectations for the instrument capabilities.

  7. Aerogel Cherenkov detector for characterizing the intense flash x-ray source, Cygnus, spectrum

    Science.gov (United States)

    Kim, Y.; Herrmann, H. W.; McEvoy, A. M.; Young, C. S.; Hamilton, C.; Schwellenbach, D. D.; Malone, R. M.; Kaufman, M. I.; Smith, A. S.

    2016-11-01

    An aerogel Cherenkov detector is proposed to measure the X-ray energy spectrum from the Cygnus—intense flash X-ray source operated at the Nevada National Security Site. An array of aerogels set at a variety of thresholds between 1 and 3 MeV will be adequate to map out the bremsstrahlung X-ray production of the Cygnus, where the maximum energy of the spectrum is normally around 2.5 MeV. In addition to the Cherenkov radiation from aerogels, one possible competing light-production mechanism is optical transition radiation (OTR), which may be significant in aerogels due to the large number of transitions from SiO2 clusters to vacuum voids. To examine whether OTR is a problem, four aerogel samples were tested using a mono-energetic electron beam (varied in the range of 1-3 MeV) at NSTec Los Alamos Operations. It was demonstrated that aerogels can be used as a Cherenkov medium, where the rate of the light production is about two orders magnitude higher when the electron beam energy is above threshold.

  8. X-ray measurement with Pin type semiconductor detectors; Medicion de rayos X con detectores de semiconductor tipo PIN

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez J, F.J. [Instituto Nacional de Investigaciones Nucleares, Departamento de Electronica, C.P. 52045 Salazar, Estado de Mexico (Mexico)

    2000-07-01

    Here are presented the experimental results of the applications of Pin type radiation detectors developed in a National Institute of Nuclear Research (ININ) project, in the measurement of low energy gamma and X-rays. The applications were oriented mainly toward the Medical Physics area. It is planned other applications which are in process of implementation inside the National Institute of Nuclear Research in Mexico. (Author)

  9. A diamond detector for inertial confinement fusion X-ray bang-time measurements at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    MacPhee, A G; Brown, C; Burns, S; Celeste, J; Glenzer, S H; Hey, D; Jones, O S; Landen, O; Mackinnon, A J; Meezan, N; Parker, J; Edgell, D; Glebov, V Y; Kilkenny, J; Kimbrough, J

    2010-11-09

    An instrument has been developed to measure X-ray bang-time for inertial confinement fusion capsules; the time interval between the start of the laser pulse and peak X-ray emission from the fuel core. The instrument comprises chemical vapor deposited polycrystalline diamond photoconductive X-ray detectors with highly ordered pyrolytic graphite X-ray monochromator crystals at the input. Capsule bang-time can be measured in the presence of relatively high thermal and hard X-ray background components due to the selective band pass of the crystals combined with direct and indirect X-ray shielding of the detector elements. A five channel system is being commissioned at the National Ignition Facility at Lawrence Livermore National Laboratory for implosion optimization measurements as part of the National Ignition Campaign. Characteristics of the instrument have been measured demonstrating that X-ray bang-time can be measured with {+-} 30ps precision, characterizing the soft X-ray drive to +/- 1eV or 1.5%.

  10. 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.

  11. A gamma- and X-ray detector for cryogenic, high magnetic field applications

    CERN Document Server

    Cooper, R L; Bales, M J; Bass, C D; Beise, E J; Breuer, H; Byrne, J; Chupp, T E; Coakley, K J; Dewey, M S; Fu, C; Gentile, T R; Mumm, H P; Nico, J S; O'Neill, B; Pulliam, K; Thompson, A K; Wietfeldt, F E

    2012-01-01

    As part of an experiment to measure the spectrum of photons emitted in beta-decay of the free neutron, we developed and operated a detector consisting of 12 bismuth germanate (BGO) crystals coupled to avalanche photodiodes (APDs). The detector was operated near liquid nitrogen temperature in the bore of a superconducting magnet and registered photons with energies from 5 keV to 1000 keV. To enlarge the detection range, we also directly detected soft X-rays with energies between 0.2 keV and 20 keV with three large area APDs. The construction and operation of the detector is presented, as well as information on operation of APDs at cryogenic temperatures.

  12. 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.

  13. Improving x-ray image resolution using subpixel shifts of the detector

    Science.gov (United States)

    Bruandet, Jean-Pierre; Dinten, Jean-Marc

    1999-05-01

    The resolution of digitized images is linked to the detector array pixel size. Aliasing effects result from a non- adequation between the detector sampling and the signal bandwidths. The aim of this study is to develop a super- resolution algorithm for X-ray images. Our technique uses controlled horizontal and vertical subpixel shifts. Generalized sampling theorem of Papoulis, based on a multichannel approach, is the theoretical justification for the recovery of a high resolution image thanks to a set of low resolution ones. A higher resolution image is recovered by a minimization of a quadratic criterion. An iterative relaxation method is used to compute the minimum. To regularize, a priori data about the signal are introduced in order to fight against noise effects. Because of the opposite effects of regularization and super-resolution an adapted regularization that preserves discontinuities has to be used. Results obtained show that our algorithm recovers high frequency components on X-ray images without noise amplification. An analysis of real acquisitions in terms of modulation transfer function (MTF) shows that we obtain, thanks to this method, a 'virtual' detector better than a low resolution one, and equivalent to a real high resolution one.

  14. Chromium compensated gallium arsenide detectors for X-ray and γ-ray spectroscopic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Veale, M.C., E-mail: matthew.veale@stfc.ac.uk [Rutherford Appleton Laboratory, Science and Technology Facilities Council, OX11 0QX (United Kingdom); Bell, S.J.; Duarte, D.D. [Rutherford Appleton Laboratory, Science and Technology Facilities Council, OX11 0QX (United Kingdom); Faculty of Engineering and Physical Sciences, University of Surrey, GU2 7XH (United Kingdom); French, M.J.; Schneider, A.; Seller, P.; Wilson, M.D. [Rutherford Appleton Laboratory, Science and Technology Facilities Council, OX11 0QX (United Kingdom); Lozinskaya, A.D.; Novikov, V.A.; Tolbanov, O.P.; Tyazhev, A.; Zarubin, A.N. [Siberian Physical–Technical Institute of Tomsk State University, Tomsk (Russian Federation)

    2014-07-01

    Semi-insulating GaAs material of 500 μm thickness grown using the Liquid Encapsulated Czochralski (LEC) method has been compensated with chromium to produce high resistivity single crystals suitable for spectroscopic imaging applications. Results are presented for the performance of three small pixel detectors each with 80×80 pixels on a 250 μm pitch, fabricated with metal contacts and bonded to a spectroscopic imaging ASIC. Current–voltage measurements demonstrated a material resistivity of 2.5×10{sup 9} Ω cm at room temperature. At an optimised bias voltage, the average energy resolution at 60 keV (FWHM) was in the range 2.8–3.3 keV per pixel. An analysis of the voltage dependent X-ray spectroscopy suggests that the electron mobility lifetime (μτ{sub e}) for each detector is in the range 2.1–4.5×10{sup −5} cm{sup 2} V{sup −1}. The spectroscopic imaging capability of the detectors is also demonstrated in X-ray absorption spectroscopy measurements.

  15. VIPIC: a custom-made detector for X-ray speckle measurements

    Energy Technology Data Exchange (ETDEWEB)

    Rumaiz, Abdul K.; Siddons, D. Peter; Deptuch, Grzegorz; Maj, Piotr; Kuczewski, Anthony J.; Carini, Gabriella A.; Narayanan, Suresh; Dufresne, Eric; Sandy, Alec; Bradford, Robert; Fluerasu, Andrei A.; Sutton, Mark

    2016-03-01

    The Vertically Integrated Photon Imaging Chip (VIPIC) was custom-designed for X-ray photon correlation spectroscopy, an application in which occupancy per pixel is low but high time resolution is needed. VIPIC operates in a sparsified streaming mode in which each detected photon is immediately read out as a time- and position-stamped event. This event stream can be fed directly to an autocorrelation engine or accumulated to form a conventional image. The detector only delivers non-zero data (sparsified readout), greatly reducing the communications overhead typical of conventional frame-oriented detectors such as charge-coupled devices or conventional hybrid pixel detectors. This feature allows continuous acquisition of data with timescales from microseconds to hours. In this work VIPIC has been used to measure X-ray photon correlation spectroscopy data on polystyrene latex ano-colliodal suspensions in glycerol and on colloidal suspensions of silica spheres in water. Relaxation times of the nano-colloids have been measured for different temperatures. These results demonstrate that VIPIC can operate continuously in the microsecond time frame, while at the same time probing longer timescales.

  16. Focal spot deblurring for high resolution direct conversion x-ray detectors

    Science.gov (United States)

    Setlur Nagesh, S. V.; Rana, R.; Russ, M.; Ionita, Ciprian N.; Bednarek, D. R.; Rudin, S.

    2016-03-01

    Small pixel high resolution direct x-ray detectors have the advantage of higher spatial sampling and decreased blurring characteristic. The limiting factors for such systems becomes the degradation due to the focal spot size. One solution is a smaller focal spot; however, this can limit the output of the x-ray tube. Here a software solution of deconvolving with an estimated focal spot blur is presented. To simulate images from a direct detector affected with focal-spot blur, first a set of high-resolution stent images (FRED from Microvention, Inc., Tustin, CA) were acquired using a 75μm pixel size Dexela-Perkin-Elmer detector and frame averaged to reduce quantum noise. Then the averaged image was blurred with a known Gaussian blur. To add noise to the blurred image a flat-field image was multiplied with the blurred image. Both the ideal and the noisy-blurred images were then deconvolved with the known Gaussian function using either threshold-based inverse filtering or Weiner deconvolution. The blur in the ideal image was removed and the details were recovered successfully. However, the inverse filtering deconvolution process is extremely susceptible to noise. The Weiner deconvolution process was able to recover more of the details of the stent from the noisy-blurred image, but for noisier images, stent details are still lost in the recovery process.

  17. Two-dimensional position-sensitive gaseous detectors for high-resolution neutron and X-ray diffraction

    CERN Document Server

    Marmotti, M; Kampmann, R

    2002-01-01

    Two-dimensional position-sensitive gaseous detectors have been developed at the Geesthacht Neutron Facility (GeNF) for high-resolution neutron and X-ray diffractometry. They are multi-wire proportional counters with delay-line readout and sensitive areas of 300 mm x 300 mm or 500 mm x 500 mm. For detecting X-rays, neutrons and hard X-rays the counters are filled with Ar/CO sub 2 , sup 3 He/CF sub 4 and Xe/CO sub 2 , respectively. One neutron detector is used at the ARES diffractometer at GKSS, which is dedicated to the analysis of residual stresses. Further ones are used for analysing textures and residual stresses at the hard-X-ray beamline PETRA-2 at HASYLAB, and one detector is being developed for the neutron reflectometer REFSANS at the research reactor FRM-II in Munich, Germany. (orig.)

  18. Combinatorial Screening of Advanced Scintillators for High Resolution X-ray Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Shifan; Tao, Dejie; Lynch, Michael; Yuan, Xianglong; Li, Yiqun

    2008-05-12

    The lack of efficient scintillators is a major problem for developing powerful x-ray detectors that are widely used in homeland security, industrial and scientific research. Intematix has developed and applied a high throughput screening process and corresponding crystal growth technology to significantly speed up the discovery process for new efficient scintillators. As a result, Intematix has invented and fabricated three new scintillators both in powder and bulk forms, which possess promising properties such as better radiation hardness and better matching for silicon diode.

  19. Real-time compression of streaming X-ray photon correlation spectroscopy area-detector data

    Science.gov (United States)

    Madden, T.; Jemian, P.; Narayanan, S.; Sandy, A. R.; Sikorski, M.; Sprung, M.; Weizeorick, J.

    2011-09-01

    We present a data acquisition system to perform on-the-fly background subtraction and lower-level discrimination compression of streaming X-ray photon correlation spectroscopy (XPCS) data from a fast charge-coupled device area detector. The system is built using a commercial frame grabber with an on-board field-programmable gate array (FPGA). The system is capable of continuously processing 60 CCD frames per second each consisting of 1024×1024 pixels with up to 64 512 photon hits per frame.

  20. Coded Mask Imaging of High Energy X-rays with CZT Detectors

    Science.gov (United States)

    Matteson, J. L.; Dowkontt, P. F.; Duttweiler, F.; Heindl, W. A.; Hink, P. L.; Huszar, G. L.; Kalemci, E.; Leblanc, P. C.; Rothschild, R. E.; Skelton, R. T.; Slavis, K. R.; Stephan, E. A.

    1998-12-01

    Coded mask imagers are appropriate for important objectives of high energy X-ray astronomy, e.g., gamma- ray burst localization, all-sky monitors and surveys, and deep surveys of limited regions. We report results from a coded mask imager developed to establish the proof-of-concept for this technique with CZT detectors. The detector is 2 mm thick with orthogonal crossed strip readout and an advanced electrode design to improve the energy resolution. Each detector face has 22 strip electrodes, and the strip pitch and pixel size are 500 microns. ASIC readout is used and the energy resolution varies from 3 to 6 keV FWHM over the 14 to 184 keV keV range. A coded mask with 2 x 2 cycles of a 23 x 23 MURA pattern (860 micron unit cell) was built from 600 micron thick tantalum to provide good X-ray modulation up to 200 keV. The detector, mask, and a tiny Gd-153 source of 41 keV X-rays were positioned with a spacing that caused the mask cells in the shadowgram to have a projected size of 1300 microns at the detector. Multiple detector positions were used to measure the shadowgram of a full mask cycle and this was recorded with 100 percent modulation transfer by the detector, due to its factor of 2.6 oversampling of the mask unit cell, and very high strip-to-strip selectivity and spatial accuracy. Deconvolution of the shadowgram produced a correlation image in which the source was detected as a 76-sigma peak with the correct FWHM and base diameter. Off-source image pixels had gaussian fluctuations that agree closely with the measurement statistics. Off-source image defects such as might be produced by systematic effects were too small to be seen and limited to <0.5 percent of the source peak. These results were obtained with the "raw" shadowgram and image; no "flat fielding" corrections were used.

  1. Multi-energy x-ray detector calibration for Te and impurity density (nZ) measurements of MCF plasmas

    Science.gov (United States)

    Maddox, J.; Pablant, N.; Efthimion, P.; Delgado-Aparicio, L.; Hill, K. W.; Bitter, M.; Reinke, M. L.; Rissi, M.; Donath, T.; Luethi, B.; Stratton, B.

    2016-11-01

    Soft x-ray detection with the new "multi-energy" PILATUS3 detector systems holds promise as a magnetically confined fusion (MCF) plasma diagnostic for ITER and beyond. The measured x-ray brightness can be used to determine impurity concentrations, electron temperatures, ne 2 Z eff products, and to probe the electron energy distribution. However, in order to be effective, these detectors which are really large arrays of detectors with photon energy gating capabilities must be precisely calibrated for each pixel. The energy-dependence of the detector response of the multi-energy PILATUS3 system with 100 K pixels has been measured at Dectris Laboratory. X-rays emitted from a tube under high voltage bombard various elements such that they emit x-ray lines from Zr-Lα to Ag-Kα between 1.8 and 22.16 keV. Each pixel on the PILATUS3 can be set to a minimum energy threshold in the range from 1.6 to 25 keV. This feature allows a single detector to be sensitive to a variety of x-ray energies, so that it is possible to sample the energy distribution of the x-ray continuum and line-emission. PILATUS3 can be configured for 1D or 2D imaging of MCF plasmas with typical spatial energy and temporal resolution of 1 cm, 0.6 keV, and 5 ms, respectively.

  2. Optimization of <= 200 um pitch CZT detectors for future high-resolution X-ray instrumentation in astrophysics

    CERN Document Server

    Zajczyk, Anna; Dowkontt, Paul; Guo, Qingzhen; Kislat, Fabian; Krawczynski, Henric; De Geronimo, Gianluigi; Li, Shaorui; Beilicke, Matthias

    2015-01-01

    Cadmium Zinc Telluride and Cadmium Telluride are the detector materials of choice for the detection of X-rays in the X-ray energy band E >= 5keV with excellent spatial and spectral resolution and without cryogenic cooling. Owing to recent breakthroughs in grazing incidence mirror technology, next-generation hard X-ray telescopes will achieve angular resolution between 5 and 10 arc seconds - about an order of magnitude better than that of the NuSTAR hard X-ray telescope. As a consequence, the next generation of X-ray telescopes will require pixelated X-ray detectors with pixels on a grid with a lattice constant of <= 250um. Additional detector requirements include a low energy threshold of less than 5keV and an energy resolution of less than one keV. The science drivers for a high angular-resolution X-ray mission include studies and measurements of black hole spins, the cosmic evolution of super-massive black holes, active galactic nuclei feedback, and the behaviour of matter at very high densities. In this...

  3. Measurements of High Energy X-Ray Dose Distributions Using Multi-Dimensional Fiber-Optic Radiation Detectors

    Science.gov (United States)

    Jang, Kyoung Won; Cho, Dong Hyun; Shin, Sang Hun; Lee, Bongsoo; Chung, Soon-Cheol; Tack, Gye-Rae; Yi, Jeong Han; Kim, Sin; Cho, Hyosung

    In this study, we have fabricated multi-dimensional fiber-optic radiation detectors with organic scintillators, plastic optical fibers and photo-detectors such as photodiode array and a charge-coupled device. To measure the X-ray dose distributions of the clinical linear accelerator in the tissue-equivalent medium, we have fabricated polymethylmethacrylate phantoms which have one-dimensional and two-dimensional fiber-optic detector arrays inside. The one-dimensional and two-dimensional detector arrays can be used to measure percent depth doses and surface dose distributions of high energy X-ray in the phantom respectively.

  4. A SOI-Based Low Noise and Wide Dynamic Range Event-Driven Detector for X-Ray Imaging

    CERN Document Server

    Shrestha, Sumeet; Kawahito, Shoji; Yasutomi, Keita; Kagawa, Keiichiro; Takeda, Ayaki; Tsuru, Takeshi Go; Arai, Yasuo

    2015-01-01

    A low noise and wide dynamic range event driven detector for the detection of X-Ray energy is realized using 0.2 [um] Silicon on insulator (SOI) technology. Pixel circuits are divided into two parts; signal sensing circuit and event detection circuit. Event detection circuit is activated when X-Ray energy falls into the detector. In-pixel gain selection is implemented for the detection of a small signal and wide band of energy particle. Adaptive gain and capability of correlated double sampling (CDS) technique for the kTC noise canceling of charge detector realizes the low noise and high dynamic range event driven detector.

  5. X-ray diffuse scattering for evaluation of wide bandgap semiconductor nuclear radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Goorsky, M.S. [University of Southern California, Los Angeles, CA (United States). Dept. of Mater. Sci. and Eng.; Yoon, H. [University of Southern California, Los Angeles, CA (United States). Dept. of Mater. Sci. and Eng.; Schieber, M. [Hebrew Univ., Jerusalem (Israel). Graduate Sch. of Appl. Sci.; James, R.B. [Sandia Nat. Labs., Livermore, CA (United States). Dept. 8347; McGregor, D.S. [Sandia Nat. Labs., Livermore, CA (United States). Dept. 8347; Natarajan, M. [TN Technol., Round Rock, TX (United States)

    1996-10-01

    The crystalline perfection of solid state radiation detectors was examined using triple axis x-ray diffraction. Triple axis techniques provide a means to analyze the origin of diffraction peak broadening: the effects of strain (due to deviations in alloy composition or stoichiometry) and lattice tilts (mosaic structure) can be separated. Cd{sub 1-x}Zn{sub x}Te (x{approx}0.1), HgI{sub 2}, and GaAs detector materials were studied. In the cases of Cd{sub 1-x}Zn{sub x}Te and HgI{sub 2} the crystalline properties of detectors with different spectral responses to {gamma}-radiation were determined. Increased mosaicity was universally found to be related to deteriorated detector properties. For Cd{sub 1-x}Zn{sub x}Te, detectors with poor performance possessed greater levels of diffuse scatter due to lattice tilts than did high quality detectors. For GaAs, low angle grain boundaries were attributed to impaired detector performance. Additionally, in large HgI{sub 2} detectors, deviations from stoichiometry were also related to reduced performance. Interestingly, HgI{sub 2} detectors which possessed a sharp spectral response to {gamma}-radiation but also showed polarization were of comparable crystallinity to those detectors which did not exhibit polarization effects. This initial analysis suggests that polarization is related to native point defects or chemical impurities which do not significantly alter the crystallinity of the material. Overall, within a given class of materials, improved detector performance (better spectral response) always correlated with better material quality. (orig.).

  6. Response functions of Si(Li), SDD and CdTe detectors for mammographic x-ray spectroscopy.

    Science.gov (United States)

    Tomal, A; Cunha, D M; Antoniassi, M; Poletti, M E

    2012-07-01

    In this work, the energy response functions of Si(Li), SDD and CdTe detectors were studied in the mammographic energy range through Monte Carlo simulation. The code was modified to take into account carrier transport effects and the finite detector energy resolution. The results obtained show that all detectors exhibit good energy response at low energies. The most important corrections for each detector were discussed, and the corrected mammographic x-ray spectra obtained with each one were compared. Results showed that all detectors provided similar corrected spectra, and, therefore, they could be used to accurate mammographic x-ray spectroscopy. Nevertheless, the SDD is particularly suitable for clinic mammographic x-ray spectroscopy due to the easier correction procedure and portability.

  7. Integrated CMOS-selenium x-ray detector for digital mammography

    Science.gov (United States)

    Andre, Michael P.; Spivey, Brett A.; Martin, Peter J.; Morsell, Arthur L.; Atlas, Eugene; Pellegrino, Tony

    1998-07-01

    This paper describes a novel area detector for direct conversion and readout of the x-ray energy that eliminates multiple conversions and coupling stages which degrade performance. The pixel array and readout electronics are fabricated on the same piece of silicon. The detector consists of a uniform layer (approximately 300 micrometers) of amorphous selenium alloy vapor-deposited on an electronic readout array fabricated using conventional complementary metal oxide semiconductor (CMOS). The CMOS array features 66 micrometer pixels in a 1024 X 832 array providing a 5.5 X 6.75 cm image area. Each pixel has active circuitry including signal amplification, pixel selection and reset, while peripheral circuitry on one end of the array provides shift registers, sample and hold and multiplexing. The CMOS readout array was fabricated at a standard facility on a 10-cm diameter silicon wafer using 2 micrometer CMOS process. Fifteen separate image sensors were assembled for evaluation in a 3 X 5 format to provide a 20 X 27 cm composite field of view. Missing data between sensors is recovered by acquiring three sub-exposures, between which the array is translated diagonally approximately 2 mm. Total exposure time for an average breast is less than one second. Conversion efficiency was found to be approximately 120 electrons per absorbed x-ray (19 keV average). Electronic readout noise was measured to be 2.4 ADU corresponding to approximately 500 electrons. Detective quantum efficiency was found to be 0.65 at low spatial frequency (0.25 lp/mm) and at 0.2 at high spatial frequency (8 lp/mm) for x-ray fluence ranging from 5 - 35 mR. Images of an ACR phantom show visualization of all of the fibers, specks and masses when displayed with a linear lookup table on a high-resolution monitor. These studies demonstrated that there is a slight but measurable image retention evident as 'ghost' images. The two most effective means to reduce this effect are flushing the sensors with infrared

  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. Characterization of CdTe sensors with Schottky contacts coupled to charge-integrating pixel array detectors for X-ray science

    Science.gov (United States)

    Becker, J.; Tate, M. W.; Shanks, K. S.; Philipp, H. T.; Weiss, J. T.; Purohit, P.; Chamberlain, D.; Ruff, J. P. C.; Gruner, S. M.

    2016-12-01

    Pixel Array Detectors (PADs) consist of an x-ray sensor layer bonded pixel-by-pixel to an underlying readout chip. This approach allows both the sensor and the custom pixel electronics to be tailored independently to best match the x-ray imaging requirements. Here we present characterizations of CdTe sensors hybridized with two different charge-integrating readout chips, the Keck PAD and the Mixed-Mode PAD (MM-PAD), both developed previously in our laboratory. The charge-integrating architecture of each of these PADs extends the instantaneous counting rate by many orders of magnitude beyond that obtainable with photon counting architectures. The Keck PAD chip consists of rapid, 8-frame, in-pixel storage elements with framing periods detector, the MM-PAD, has an extended dynamic range by utilizing an in-pixel overflow counter coupled with charge removal circuitry activated at each overflow. This allows the recording of signals from the single-photon level to tens of millions of x-rays/pixel/frame while framing at 1 kHz. Both detector chips consist of a 128 × 128 pixel array with (150 μm)2 pixels.

  10. High-speed imaging at high x-ray energy: CdTe sensors coupled to charge-integrating pixel array detectors

    Energy Technology Data Exchange (ETDEWEB)

    Becker, Julian; Tate, Mark W.; Shanks, Katherine S.; Philipp, Hugh T.; Weiss, Joel T.; Purohit, Prafull [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853 (United States); Chamberlain, Darol [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States); Gruner, Sol M., E-mail: smg26@cornell.edu [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853 (United States); Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States)

    2016-07-27

    Pixel Array Detectors (PADs) consist of an x-ray sensor layer bonded pixel-by-pixel to an underlying readout chip. This approach allows both the sensor and the custom pixel electronics to be tailored independently to best match the x-ray imaging requirements. Here we describe the hybridization of CdTe sensors to two different charge-integrating readout chips, the Keck PAD and the Mixed-Mode PAD (MM-PAD), both developed previously in our laboratory. The charge-integrating architecture of each of these PADs extends the instantaneous counting rate by many orders of magnitude beyond that obtainable with photon counting architectures. The Keck PAD chip consists of rapid, 8-frame, in-pixel storage elements with framing periods <150 ns. The second detector, the MM-PAD, has an extended dynamic range by utilizing an in-pixel overflow counter coupled with charge removal circuitry activated at each overflow. This allows the recording of signals from the single-photon level to tens of millions of x-rays/pixel/frame while framing at 1 kHz. Both detector chips consist of a 128×128 pixel array with (150 µm){sup 2} pixels.

  11. Characterization of Si Hybrid CMOS Detectors for use in the Soft X-ray Band

    CERN Document Server

    Prieskorn, Zachary; Bongiorno, Stephen D; Falcone, Abraham D; Burrows, David N

    2013-01-01

    We report on the characterization of four Teledyne Imaging Systems HAWAII Hybrid Si CMOS detectors designed for X-ray detection. Three H1RG detectors were studied along with a specially configured H2RG. Read noise measurements were performed, with the lowest result being 7.1 e- RMS. Interpixel capacitive crosstalk (IPC) was measured for the three H1RGs and for the H2RG. The H1RGs had IPC upper limits of 4.0 - 5.5 % (up & down pixels) and 8.7 - 9.7 % (left & right pixels), indicating a clear asymmetry. Energy resolution is reported for two X-ray lines, 1.5 & 5.9 keV, at multiple temperatures between 150 - 210 K. The best resolution measured at 5.9 keV was 250 eV (4.2 %) at 150 K, with IPC contributing significantly to this measured energy distribution. The H2RG, with a unique configuration designed to decrease the capacitive coupling between ROIC pixels, had an IPC of 1.8 +/- 1.0 % indicating a dramatic improvement in IPC with no measurable asymmetry. We also measured dark current as a function of ...

  12. Characterization of X-ray polycapillary optics by LiF crystal radiation detectors through confocal fluorescence microscopy

    Science.gov (United States)

    Bonfigli, Francesca; Hampai, Dariush; Dabagov, Sultan B.; Montereali, Rosa Maria

    2016-08-01

    Solid-state radiation imaging detectors based on photoluminescent colour centres in lithium fluoride (LiF) crystals have been successfully tested for both advanced 2D and 3D characterizations of X-ray polycapillary optics by a table-top laboratory system. Polycapillary optics can control X-ray beams propagation and allows obtaining quasi-parallel beam (half-lens) or focused beams (full-lens). The combination of a fine-focused micro X-ray tube and a polycapillary lens can provide the high intensity radiation fluxes that are necessary for high resolution X-ray imaging. In this paper we present novel results about advanced characterization of these complex optics by 2D as well as 3D confocal laser fluorescence microscopy of X-ray irradiated LiF crystal detectors. Two dimensional high spatial resolution images on a wide field of view of transmitted X-rays through a semi-lens and 3D direct inspection of the coloured volumes produced in LiF crystals by both focused and parallel X-ray beam transmitted by a full and a semi-lens, respectively, as well as their 3D reconstructions were obtained. The results show that the photoluminescent colour centres volume in LiF crystals combined with an optical sectioning reading system provide information about tomography of transmitted X-ray beams by policapillary optics in a single exposure process. For the first time, the use of LiF crystal plates as versatile radiation imaging luminescent detectors have been used to characterize the operation of polycapillary optics as X-ray lens, in focusing and parallel mode.

  13. Superiority of zoom lens coupling in designing a novel X-ray image detector

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We design a novel X-ray image detector by lens coupling a Gd2O2S:Tb intensifying screen with a high performance low-light-level (L3,which often means luminescence less than 10-3 Lux) image intensifier.Different coupling effects on imaging performance between zoom lens and fix-focus lens are analyzed theoretically.In experiment,for designing a detector of 15-inch visual field,the system coupled by zoom lens is of 12.25-1p/cm resolution,while the one with fix-focus lens is 10 lp/cm.The superiority of zoom lens is validated.It is concluded that zoom lens preserves the image information better than fix-focus lens and improves the imaging system's performance in this design,which is referential to the design of other optical imaging systems.

  14. A New Gated X-Ray Detector for the Orion Laser Facility

    Energy Technology Data Exchange (ETDEWEB)

    Clark, David D. [Los Alamos National Laboratory; Aragonez, Robert J. [Los Alamos National Laboratory; Archuleta, Thomas N. [Los Alamos National Laboratory; Fatherley, Valerie E. [Los Alamos National Laboratory; Hsu, Albert H. [Los Alamos National Laboratory; Jorgenson, H. J. [Los Alamos National Laboratory; Mares, Danielle [Los Alamos National Laboratory; Oertel, John A. [Los Alamos National Laboratory; Oades, Kevin [Atomic Weapons Establishment; Kemshall, Paul [Atomic Weapons Establishment; Thomas, Philip [Atomic Weapons Establishment; Young, Trevor [Atomic Weapons Establishment; Pederson, Neal [VI Control Systems

    2012-08-08

    Gated X-Ray Detectors (GXD) are considered the work-horse target diagnostic of the laser based inertial confinement fusion (ICF) program. Recently, Los Alamos National Laboratory (LANL) has constructed three new GXDs for the Orion laser facility at the Atomic Weapons Establishment (AWE) in the United Kingdom. What sets these three new instruments apart from the what has previously been constructed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is: improvements in detector head microwave transmission lines, solid state embedded hard drive and updated control software, and lighter air box design and other incremental mechanical improvements. In this paper we will present the latest GXD design enhancements and sample calibration data taken on the Trident laser facility at Los Alamos National Laboratory using the newly constructed instruments.

  15. Design and image-quality performance of high resolution CMOS-based X-ray imaging detectors for digital mammography

    Science.gov (United States)

    Cha, B. K.; Kim, J. Y.; Kim, Y. J.; Yun, S.; Cho, G.; Kim, H. K.; Seo, C.-W.; Jeon, S.; Huh, Y.

    2012-04-01

    In digital X-ray imaging systems, X-ray imaging detectors based on scintillating screens with electronic devices such as charge-coupled devices (CCDs), thin-film transistors (TFT), complementary metal oxide semiconductor (CMOS) flat panel imagers have been introduced for general radiography, dental, mammography and non-destructive testing (NDT) applications. Recently, a large-area CMOS active-pixel sensor (APS) in combination with scintillation films has been widely used in a variety of digital X-ray imaging applications. We employed a scintillator-based CMOS APS image sensor for high-resolution mammography. In this work, both powder-type Gd2O2S:Tb and a columnar structured CsI:Tl scintillation screens with various thicknesses were fabricated and used as materials to convert X-ray into visible light. These scintillating screens were directly coupled to a CMOS flat panel imager with a 25 × 50 mm2 active area and a 48 μm pixel pitch for high spatial resolution acquisition. We used a W/Al mammographic X-ray source with a 30 kVp energy condition. The imaging characterization of the X-ray detector was measured and analyzed in terms of linearity in incident X-ray dose, modulation transfer function (MTF), noise-power spectrum (NPS) and detective quantum efficiency (DQE).

  16. Improvement of density resolution in short-pulse hard x-ray radiographic imaging using detector stacks

    Science.gov (United States)

    Borm, B.; Gärtner, F.; Khaghani, D.; Neumayer, P.

    2016-09-01

    We demonstrate that stacking several imaging plates (IPs) constitutes an easy method to increase hard x-ray detection efficiency. Used to record x-ray radiographic images produced by an intense-laser driven hard x-ray backlighter source, the IP stacks resulted in a significant improvement of the radiograph density resolution. We attribute this to the higher quantum efficiency of the combined detectors, leading to a reduced photon noise. Electron-photon transport simulations of the interaction processes in the detector reproduce the observed contrast improvement. Increasing the detection efficiency to enhance radiographic imaging capabilities is equally effective as increasing the x-ray source yield, e.g., by a larger drive laser energy.

  17. Improvement of density resolution in short-pulse hard x-ray radiographic imaging using detector stacks

    Energy Technology Data Exchange (ETDEWEB)

    Borm, B.; Gärtner, F.; Khaghani, D. [GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany); Johann Wolfgang Goethe-Universität, Frankfurt am Main (Germany); Neumayer, P. [GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt (Germany)

    2016-09-15

    We demonstrate that stacking several imaging plates (IPs) constitutes an easy method to increase hard x-ray detection efficiency. Used to record x-ray radiographic images produced by an intense-laser driven hard x-ray backlighter source, the IP stacks resulted in a significant improvement of the radiograph density resolution. We attribute this to the higher quantum efficiency of the combined detectors, leading to a reduced photon noise. Electron-photon transport simulations of the interaction processes in the detector reproduce the observed contrast improvement. Increasing the detection efficiency to enhance radiographic imaging capabilities is equally effective as increasing the x-ray source yield, e.g., by a larger drive laser energy.

  18. Flat panel X-ray detector with reduced internal scattering for improved attenuation accuracy and dynamic range

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Peter D. (Santa Fe, NM); Claytor, Thomas N. (White Rock, NM); Berry, Phillip C. (Albuquerque, NM); Hills, Charles R. (Los Alamos, NM)

    2010-10-12

    An x-ray detector is disclosed that has had all unnecessary material removed from the x-ray beam path, and all of the remaining material in the beam path made as light and as low in atomic number as possible. The resulting detector is essentially transparent to x-rays and, thus, has greatly reduced internal scatter. The result of this is that x-ray attenuation data measured for the object under examination are much more accurate and have an increased dynamic range. The benefits of this improvement are that beam hardening corrections can be made accurately, that computed tomography reconstructions can be used for quantitative determination of material properties including density and atomic number, and that lower exposures may be possible as a result of the increased dynamic range.

  19. Development of the superconducting detectors and read-out for the X-IFU instrument on board of the X-ray observatory Athena

    CERN Document Server

    Gottardi, Luciano; Bruijn, Marcel P; Hartog, Roland den; Herder, Jan-Willem den; Jackson, Brian; Kiviranta, Mikko; van der Kuur, Jan; van Weers, Henk

    2016-01-01

    The Advanced Telescope for High-Energy Astrophysics (Athena) has been selected by ESA as its second large-class mission. The future European X-ray observatory will study the hot and energetic Universe with its launch foreseen in 2028. Microcalorimeters based on superconducting Transition-edge sensor (TES) are the chosen technology for the detectors array of the X-ray Integral Field Unit (X-IFU) on board of Athena. The X-IFU is a 2-D imaging integral-field spectrometer operating in the soft X-ray band (0.3 -12 keV). The detector consists of an array of 3840 TESs coupled to X-ray absorbers and read out in the MHz bandwidth using Frequency Domain Multiplexing (FDM) based on Superconducting QUantum Interference Devices (SQUIDs). The proposed design calls for devices with a high filling-factor, high quantum e?ciency, relatively high count-rate capability and an energy resolution of 2.5 eV at 5.9 keV. The paper will review the basic principle and the physics of the TES-based microcalorimeters and present the state-...

  20. Development of the superconducting detectors and read-out for the X-IFU instrument on board of the X-ray observatory Athena

    Energy Technology Data Exchange (ETDEWEB)

    Gottardi, L., E-mail: l.gottardi@sron.nl [SRON Netherlands Institute for Space Research, Utrecht (Netherlands); Akamatsu, H.; Bruijn, M.P.; Hartog, R. den; Herder, J.-W. den; Jackson, B. [SRON Netherlands Institute for Space Research, Utrecht (Netherlands); Kiviranta, M. [VTT, Espoo (Finland); Kuur, J. van der; Weers, H. van [SRON Netherlands Institute for Space Research, Utrecht (Netherlands)

    2016-07-11

    The Advanced Telescope for High-Energy Astrophysics (Athena) has been selected by ESA as its second large-class mission. The future European X-ray observatory will study the hot and energetic Universe with its launch foreseen in 2028. Microcalorimeters based on superconducting Transition-edge sensor (TES) are the chosen technology for the detectors array of the X-ray Integral Field Unit (X-IFU) on board of Athena. The X-IFU is a 2-D imaging integral-field spectrometer operating in the soft X-ray band (0.3–12 keV). The detector consists of an array of 3840 TESs coupled to X-ray absorbers and read out in the MHz bandwidth using Frequency Domain Multiplexing (FDM) based on Superconducting QUantum Interference Devices (SQUIDs). The proposed design calls for devices with a high filling-factor, high quantum efficiency, relatively high count-rate capability and an energy resolution of 2.5 eV at 5.9 keV. The paper will review the basic principle and the physics of the TES-based microcalorimeters and present the state-of-the art of the FDM read-out.

  1. Development of the superconducting detectors and read-out for the X-IFU instrument on board of the X-ray observatory Athena

    Science.gov (United States)

    Gottardi, L.; Akamatsu, H.; Bruijn, M. P.; den Hartog, R.; den Herder, J.-W.; Jackson, B.; Kiviranta, M.; van der Kuur, J.; van Weers, H.

    2016-07-01

    The Advanced Telescope for High-Energy Astrophysics (Athena) has been selected by ESA as its second large-class mission. The future European X-ray observatory will study the hot and energetic Universe with its launch foreseen in 2028. Microcalorimeters based on superconducting Transition-edge sensor (TES) are the chosen technology for the detectors array of the X-ray Integral Field Unit (X-IFU) on board of Athena. The X-IFU is a 2-D imaging integral-field spectrometer operating in the soft X-ray band (0.3-12 keV). The detector consists of an array of 3840 TESs coupled to X-ray absorbers and read out in the MHz bandwidth using Frequency Domain Multiplexing (FDM) based on Superconducting QUantum Interference Devices (SQUIDs). The proposed design calls for devices with a high filling-factor, high quantum efficiency, relatively high count-rate capability and an energy resolution of 2.5 eV at 5.9 keV. The paper will review the basic principle and the physics of the TES-based microcalorimeters and present the state-of-the art of the FDM read-out.

  2. 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.

  3. 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.

  4. Taheri-Saramad x-ray detector (TSXD): A novel high spatial resolution x-ray imager based on ZnO nano scintillator wires in polycarbonate membrane

    Energy Technology Data Exchange (ETDEWEB)

    Taheri, A., E-mail: at1361@aut.ac.ir; Saramad, S.; Ghalenoei, S.; Setayeshi, S. [Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran 15875-4413 (Iran, Islamic Republic of)

    2014-01-15

    A novel x-ray imager based on ZnO nanowires is designed and fabricated. The proposed architecture is based on scintillation properties of ZnO nanostructures in a polycarbonate track-etched membrane. Because of higher refractive index of ZnO nanowire compared to the membrane, the nanowire acts as an optical fiber that prevents the generated optical photons to spread inside the detector. This effect improves the spatial resolution of the imager. The detection quantum efficiency and spatial resolution of the fabricated imager are 11% and <6.8 μm, respectively.

  5. Taheri-Saramad x-ray detector (TSXD): A novel high spatial resolution x-ray imager based on ZnO nano scintillator wires in polycarbonate membrane

    Science.gov (United States)

    Taheri, A.; Saramad, S.; Ghalenoei, S.; Setayeshi, S.

    2014-01-01

    A novel x-ray imager based on ZnO nanowires is designed and fabricated. The proposed architecture is based on scintillation properties of ZnO nanostructures in a polycarbonate track-etched membrane. Because of higher refractive index of ZnO nanowire compared to the membrane, the nanowire acts as an optical fiber that prevents the generated optical photons to spread inside the detector. This effect improves the spatial resolution of the imager. The detection quantum efficiency and spatial resolution of the fabricated imager are 11% and <6.8 μm, respectively.

  6. The ^{55}Fe X-ray Energy Response of Mercury Cadmium Telluride Near-Infrared Detector Arrays

    CERN Document Server

    Fox, Ori D; Wen, Yiting; Foltz, Roger D; Hill, Robert J; Kimble, Randy A; Malumuth, Eliot; Rauscher, Bernard J

    2009-01-01

    A technique involving ^{55}Fe X-rays provides a straightforward method to measure the response of a detector. The detector's response can lead directly to a calculation of the conversion gain (e^- ADU^{-1}), as well as aid detector design and performance studies. We calibrate the ^{55}Fe X-ray energy response and pair production energy of HgCdTe using 8 HST WFC3 1.7 \\micron flight grade detectors. The results show that each K$\\alpha$ X-ray generates 2273 \\pm 137 electrons, which corresponds to a pair-production energy of 2.61 \\pm 0.16 eV. The uncertainties are dominated by our knowledge of the conversion gain. In future studies, we plan to eliminate this uncertainty by directly measuring conversion gain at very low light levels.

  7. The analysis of X-ray response of CdZnTe detectors

    Institute of Scientific and Technical Information of China (English)

    ZHA GangQiang; XIANG Hang; LIU Ting; XU YaDong; WANG Tao; JIE WanQi

    2012-01-01

    CdZnTe is an excellent material candidate for high efficiency,high-resolution room-temperature nuclear radiation detectors,and the CdZnTe detectors are being widely used in medicine,industry,safeguard and scientific X-ray and γ-ray imaging and spectroscopic applications.In this work,three CdZnTe planar detectors with different grades,named CZT-1,CZT-2 and CZT-3,respectively,were fabricated.And the effects of mobility,lifetime and de-trapping time on the performance of CdZnTe planar detector,such as the energy rcsolution,charge collection efficiency and peak to valley ratio,were analyzed.The charge collection efficiency depends on the product of carrier mobility and lifetime,which has a great effect on the energy resolution of detector when the efficiency is less than 90%.The de-trapping time of carriers in deep levels should be responsible for the peak to valley ratio and "polarization".

  8. X-ray Hybrid CMOS Detectors : Recent progress in development and characterization

    Science.gov (United States)

    Chattopadhyay, Tanmoy; Falcone, Abraham; Burrows, David N.

    2017-08-01

    PennState high energy astronomy laboratory has been working on the development and characterization of Hybrid CMOS Detectors (HCDs) for last few years in collaboration with Teledyne Imaging Sensors (TIS). HCDs are preferred over X-ray CCDs due to their higher and flexible read out rate, radiation hardness and low power which make them more suitable for next generation large area X-ray telescopic missions. An H2RG detector with 36 micron pixel pitch and 18 micron ROIC, has been selected for a sounding rocket flight in 2018. The H2RG detector provides ~2.5 % energy resolution at 5.9 keV and ~7 e- read noise when coupled to a cryo-SIDECAR. We could also detect a clear Oxygen line (~0.5 keV) from the detector implying a lower energy threshold of ~0.3 keV. Further improvement in the energy resolution and read noise is currently under progress. We have been working on the characterization of small pixel HCDs (12.5 micron pixel; smallest pixel HCDs developed so far) which is important for the development of next generation high resolution X-ray spectroscopic instrument based on HCDs. Event recognition in HCDs is another exciting prospect which have been successfully shown to work with a 64 X 64 pixel prototype SPEEDSTAR-EXD which use comparators at each pixel to read out only those pixels having detectable signal, thereby providing an order of magnitude improvement in the read out rate. Currently, we are working on the development of a large area SPEEDSTAR-EXD array for the development of a full fledged instrument. HCDs due to their fast read out, can also be explored as a large FOV instrument to study GRB afterglows and variability and spectroscopic study of other astrophysical transients. In this context, we are characterizing a Lobster-HCD system at multiple energies and multiple off-axis angles for future rocket or CubeSate experiments. In this presentation, I will briefly present these new developments and experiments with HCDs and the analysis techniques.

  9. X-Ray Detector-on-Plastic with High Sensitivity Using Low Cost, Solution-Processed Organic Photodiodes

    NARCIS (Netherlands)

    Gelinck, G.H.; Kumar, A.; Moet, D.; Steen, J.L.P.J. van der; Breemen, A.J.J.M. van; Shanmugam, S.; Langen, A.; Gilot, J.; Groen, W.A.; Andriessen, H.A.J.M.; Simon, M.; Ruetten, W.; Douglas, A.U.; Raaijmakers, R.; Malinowski, P.E.; Myny, K.

    2016-01-01

    We made and characterized an X-ray detector on a 25-ìm-thick plastic substrate that is capable of medicalgrade performance. As an indirect conversion flat panel detector, it combined a standard scintillator with an organic photodetector (OPD) layer and oxide thin-film transistor backplane. Using sol

  10. X-ray dose detector based on color changing of light-emitting polymer–metal complex hybrid material.

    OpenAIRE

    2012-01-01

    We report on the design, fabrication and performance of a poly (2-methoxy-5(2_-ethylhexyloxy)- p-phenylenevinylene)/tris-(8-hydroxyquinoline)aluminum (MEH-PPV/Alq3) X-ray dose detector for improving safety for cancer patients shortly before radiation therapy. The detector consists of an inexpen-sive (

  11. X-Ray Detector-on-Plastic with High Sensitivity Using Low Cost, Solution-Processed Organic Photodiodes

    NARCIS (Netherlands)

    Gelinck, G.H.; Kumar, A.; Moet, D.; Steen, J.L.P.J. van der; Breemen, A.J.J.M. van; Shanmugam, S.; Langen, A.; Gilot, J.; Groen, W.A.; Andriessen, H.A.J.M.; Simon, M.; Ruetten, W.; Douglas, A.U.; Raaijmakers, R.; Malinowski, P.E.; Myny, K.

    2016-01-01

    We made and characterized an X-ray detector on a 25-ìm-thick plastic substrate that is capable of medicalgrade performance. As an indirect conversion flat panel detector, it combined a standard scintillator with an organic photodetector (OPD) layer and oxide thin-film transistor backplane. Using sol

  12. Graphical user interface for a dual-module EMCCD x-ray detector array

    Science.gov (United States)

    Wang, Weiyuan; Ionita, Ciprian; Kuhls-Gilcrist, Andrew; Huang, Ying; Qu, Bin; Gupta, Sandesh K.; Bednarek, Daniel R.; Rudin, Stephen

    2011-03-01

    A new Graphical User Interface (GUI) was developed using Laboratory Virtual Instrumentation Engineering Workbench (LabVIEW) for a high-resolution, high-sensitivity Solid State X-ray Image Intensifier (SSXII), which is a new x-ray detector for radiographic and fluoroscopic imaging, consisting of an array of Electron-Multiplying CCDs (EMCCDs) each having a variable on-chip electron-multiplication gain of up to 2000x to reduce the effect of readout noise. To enlarge the field-of-view (FOV), each EMCCD sensor is coupled to an x-ray phosphor through a fiberoptic taper. Two EMCCD camera modules are used in our prototype to form a computer-controlled array; however, larger arrays are under development. The new GUI provides patient registration, EMCCD module control, image acquisition, and patient image review. Images from the array are stitched into a 2kx1k pixel image that can be acquired and saved at a rate of 17 Hz (faster with pixel binning). When reviewing the patient's data, the operator can select images from the patient's directory tree listed by the GUI and cycle through the images using a slider bar. Commonly used camera parameters including exposure time, trigger mode, and individual EMCCD gain can be easily adjusted using the GUI. The GUI is designed to accommodate expansion of the EMCCD array to even larger FOVs with more modules. The high-resolution, high-sensitivity EMCCD modular-array SSXII imager with the new user-friendly GUI should enable angiographers and interventionalists to visualize smaller vessels and endovascular devices, helping them to make more accurate diagnoses and to perform more precise image-guided interventions.

  13. Two dimensional extensible array configuration for EMCCD-based solid state x-ray detectors.

    Science.gov (United States)

    Sharma, P; Vasan, S N Swetadri; Cartwright, A N; Titus, A H; Bednarek, D R; Rudin, S

    2012-01-01

    We have designed and developed from the discrete component level a high resolution dynamic x- ray detector to be used for fluoroscopic and angiographic medical imaging. The heart of the detector is a 1024 × 1024 pixel electron multiplying charge coupled device (EMCCD) with a pixel size of 13 × 13 μm(2) (Model CCD201-20, e2v Technologies, Inc.), bonded to a fiber optic plate (FOP), and optically coupled to a 350 μm thick micro-columnar CsI(TI) scintillator via a fiber optic taper (FOT). Our aim is to design an array of these detectors that could be extended to any arbitrary X × Y size in two dimensions to provide a larger field of view (FOV). A physical configuration for a 3×3 array is presented that includes two major sub-systems. First is an optical front end that includes (i) a phosphor to convert the x-ray photons into light photons, and (ii) a fused array of FOTs that focuses light photons from the phosphor onto an array of EMCCD's optically coupled using FOPs. Second is an electronic front end that includes (i) an FPGA board used for generating clocks and for data acquisition (ii) driver boards to drive and digitize the analog output from the EMCCDs, (iii) a power board, and (iv) headboards to hold the EMCCD's while they are connected to their respective driver board using flex cables. This configuration provides a larger FOV as well as region-of- interest (ROI) high-resolution imaging as required by modern neurovascular procedures.

  14. Two dimensional extensible array configuration for EMCCD-based solid state x-ray detectors

    Science.gov (United States)

    Sharma, P.; Swetadri Vasan, S. N.; Cartwright, A. N.; Titus, A. H.; Bednarek, D. R.; Rudin, S.

    2012-03-01

    We have designed and developed from the discrete component level a high resolution dynamic x-ray detector to be used for fluoroscopic and angiographic medical imaging. The heart of the detector is a 1024 ×1024 pixel electron multiplying charge coupled device (EMCCD) with a pixel size of 13 × 13 μm2 (Model CCD201-20, e2v Technologies, Inc.), bonded to a fiber optic plate (FOP), and optically coupled to a 350 μm thick micro-columnar CsI(TI) scintillator via a fiber optic taper (FOT). Our aim is to design an array of these detectors that could be extended to any arbitrary X × Y size in two dimensions to provide a larger field of view (FOV). A physical configuration for a 3×3 array is presented that includes two major sub-systems. First is an optical front end that includes (i) a phosphor to convert the x-ray photons into light photons, and (ii) a fused array of FOTs that focuses light photons from the phosphor onto an array of EMCCD's optically coupled using FOPs. Second is an electronic front end that includes (i) an FPGA board used for generating clocks and for data acquisition (ii) driver boards to drive and digitize the analog output from the EMCCDs, (iii) a power board, and (iv) headboards to hold the EMCCD's while they are connected to their respective driver board using flex cables. This configuration provides a larger FOV as well as region-of-interest (ROI) high-resolution imaging as required by modern neurovascular procedures.

  15. Development of a fast pixel array detector for use in microsecond time-resolved x-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Barna, S.L.; Gruner, S.M.; Shepherd, J.A. [Princeton Univ., NJ (United States)] [and others

    1995-08-01

    A large-area pixel x-ray detector is being developed to collect eight successive frames of wide dynamic range two-dimensional images at 200kHz rates. Such a detector, in conjunction with a synchrotron radiation x-ray source, will enable time-resolved x-ray studies of proteins and other materials on time scales which have previously been inaccessible. The detector will consist of an array of fully-depleted 150 micron square diodes connected to a CMOS integrated electronics layer with solder bump-bonding. During each framing period, the current resulting from the x-rays stopped in the diodes is integrated in the electronics layer, and then stored in one of eight storage capacitors underneath the pixel. After the last frame, the capacitors are read out at standard data transmission rates. The detector has been designed for a well-depth of at least 10,000 x-rays (at 20keV), and a noise level of one x-ray. Ultimately, the authors intend to construct a detector with over one million pixels (1024 by 1024). They present the results of their development effort and various features of the design. The electronics design is discussed, with special attention to the performance requirements. The choice and design of the detective diodes, as they relate to x-ray stopping power and charge collection, are presented. An analysis of various methods of bump bonding is also presented. Finally, the authors discuss the possible need for a radiation-blocking layer, to be placed between the electronics and the detective layer, and various methods they have pursued in the construction of such a layer.

  16. A 2×2 array of EMCCD-based solid state x-ray detectors.

    Science.gov (United States)

    Sharma, P; Swetadri Vasan, S N; Titus, A H; Cartwright, A N; Bednarek, D R; Rudin, S

    2012-01-01

    We have designed and developed a new solid-state x-ray imaging system that consists of a 2×2 array of electron multiplying charge coupled devices (EMCCDs). This system is intended for fluoroscopic and angiographic medical imaging. The key components are the four 1024 × 1024 pixel EMCCDs with a pixel size of 13 × 13 µm(2). Each EMCCD is bonded to a fiber optic plate (FOP), and optically coupled to a 350 µm thick micro-columnar CsI(TI) scintillator via a 3.22∶1 fiber optic taper (FOT). The detector provides x-ray images of 9 line pairs/mm resolution at 15 frames/sec and real-time live video at 30 frames/sec with binning at a lower resolution, independent of the electronic gain applied to the EMCCD. The total field of view (FOV) of the array is 8.45 cm × 8.45 cm. The system is designed to also provide the ability to do region-of- interest imaging (ROI) by selectively enabling individual modules of the array.

  17. High resolution X-ray detector for synchrotron-based microtomography

    CERN Document Server

    Stampanoni, M; Wyss, P; Abela, R; Patterson, B; Hunt, S; Vermeulen, D; Rueegsegger, P

    2002-01-01

    Synchrotron-based microtomographic devices are powerful, non-destructive, high-resolution research tools. Highly brilliant and coherent X-rays extend the traditional absorption imaging techniques and enable edge-enhanced and phase-sensitive measurements. At the Materials Science Beamline MS of the Swiss Light Source (SLS), the X-ray microtomographic device is now operative. A high performance detector based on a scintillating screen optically coupled to a CCD camera has been developed and tested. Different configurations are available, covering a field of view ranging from 715x715 mu m sup 2 to 7.15x7.15 mm sup 2 with magnifications from 4x to 40x. With the highest magnification 480 lp/mm had been achieved at 10% modulation transfer function which corresponds to a spatial resolution of 1.04 mu m. A low-noise fast-readout CCD camera transfers 2048x2048 pixels within 100-250 ms at a dynamic range of 12-14 bit to the file server. A user-friendly graphical interface gives access to the main parameters needed for ...

  18. Collecting data in the home laboratory: evolution of X-ray sources, detectors and working practices.

    Science.gov (United States)

    Skarzynski, Tadeusz

    2013-07-01

    While the majority of macromolecular X-ray data are currently collected using highly efficient beamlines at an ever-increasing number of synchrotrons, there is still a need for high-performance reliable systems for in-house experiments. In addition to crystal screening and optimization of data-collection parameters before a synchrotron trip, the home system allows the collection of data as soon as the crystals are produced to obtain the solution of novel structures, especially by the molecular-replacement method, and is invaluable in achieving the quick turnover that is often required for ligand-binding studies in the pharmaceutical industry. There has been a continuous evolution of X-ray sources, detectors and software developed for in-house use in recent years and a diverse range of tools for structural biology laboratories are available. An overview of the main directions of these developments and examples of specific solutions available to the macromolecular crystallography community are presented in this paper, showing that data collection `at home' is still an attractive proposition complementing the use of synchrotron beamlines.

  19. The speedster-EXD - A new event-triggered hybrid CMOS x-ray detector

    CERN Document Server

    Griffith, Christopher V; Prieskorn, Zachary R; Burrows, David N

    2014-01-01

    We present preliminary characterization of the Speedster-EXD, a new event driven hybrid CMOS detector (HCD) developed in collaboration with Penn State University and Teledyne Imaging Systems. HCDs have advantages over CCDs including lower susceptibility to radiation damage, lower power consumption, and faster read-out time to avoid pile-up. They are deeply depleted and able to detect x-rays down to approximately 0.1 keV. The Speedster-EXD has additional in-pixel features compared to previously published HCDs including: (1) an in-pixel comparator that enables read out of only the pixels with signal from an x-ray event, (2) four different gain modes to optimize either full well capacity or energy resolution, (3) in-pixel CDS subtraction to reduce read noise, and (4) a low-noise, high-gain CTIA amplifier to eliminate interpixel capacitance crosstalk. When using the comparator feature, the user can set a comparator threshold and only pixels above the threshold will be read out. This feature can be run in two mode...

  20. Large angle solid state position sensitive x-ray detector system

    Science.gov (United States)

    Kurtz, D.S.; Ruud, C.O.

    1998-03-03

    A method and apparatus for x-ray measurement of certain properties of a solid material are disclosed. In distinction to known methods and apparatus, this invention employs a specific fiber-optic bundle configuration, termed a reorganizer, itself known for other uses, for coherently transmitting visible light originating from the scintillation of diffracted x-radiation from the solid material gathered along a substantially one dimensional linear arc, to a two-dimensional photo-sensor array. The two-dimensional photodetector array, with its many closely packed light sensitive pixels, is employed to process the information contained in the diffracted radiation and present the information in the form of a conventional x-ray diffraction spectrum. By this arrangement, the angular range of the combined detector faces may be increased without loss of angular resolution. Further, the prohibitively expensive coupling together of a large number of individual linear diode photodetectors, which would be required to process signals generated by the diffracted radiation, is avoided. 7 figs.

  1. Development of Position-sensitive Transition-edge Sensor X-ray Detectors

    Science.gov (United States)

    Smith, S. J.; Bandler, S. R.; Brekosky, R. P.; Brown, A.-D.; Chervenak, J. A.; Eckard, M. E.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. s.; Sad (eor. K/ E/); Figueroa-Feliciano, E.

    2008-01-01

    We report on the development of position-sensitive transition-edge sensors (PoST's) for future x-ray astronomy missions such as the International X-ray Observatory (IXO), currently under study by NASA and ESA. PoST's consist of multiple absorbers each with a different thermal coupling to one or more transition-edge sensor (TES). This differential thermal coupling between absorbers and TES's results in different characteristic pulse shapes and allows position discrimination between the different pixels. The development of PoST's is motivated by a desire to achieve maximum focal-plane area with the least number of readout channels and as such. PoST's are ideally suited to provide a focal-plane extension to the Constellation-X microcalorimeter array. We report the first experimental results of our latest one and two channel PoST's, which utilize fast thermalizing electroplated Au/Bi absorbers coupled to low noise Mo/Au TES's - a technology already successfully implemented in our arrays of single pixel TES's. We demonstrate 6 eV energy resolution coupled with spatial sensitivity in the keV energy range. We also report on the development of signal processing algorithms to optimize energy and position sensitivity of our detectors.

  2. Efficient, Non-Iterative Estimator for Imaging Contrast Agents With Spectral X-Ray Detectors.

    Science.gov (United States)

    Alvarez, Robert E

    2016-04-01

    An estimator to image contrast agents and body materials with x-ray spectral measurements is described. The estimator is usable with the three or more basis functions that are required to represent the attenuation coefficient of high atomic number materials. The estimator variance is equal to the Cramèr-Rao lower bound (CRLB) and it is unbiased. Its parameters are computed from measurements of a calibration phantom with the clinical x-ray system and it is non-iterative. The estimator is compared with an iterative maximum likelihood estimator. The estimator first computes a linearized maximum likelihood estimate of the line integrals of the basis set coefficients. Corrections for errors in the initial estimates are computed by interpolation with calibration phantom data. The final estimate is the initial estimate plus the correction. The performance of the estimator is measured using a Monte Carlo simulation. Random photon counting with pulse height analysis data are generated. The mean squared errors of the estimates are compared to the CRLB. The random data are also processed with an iterative maximum likelihood estimator. Previous implementations of iterative estimators required advanced physics instruments not usually available in clinical institutions. The estimator mean squared error is essentially equal to the CRLB. The estimator outputs are close to those of the iterative estimator but the computation time is approximately 180 times shorter. The estimator is efficient and has advantages over alternate approaches such as iterative estimators.

  3. Asymmetry of characteristic X-ray peaks obtained by a Si(Li) detector

    Energy Technology Data Exchange (ETDEWEB)

    Visnovezky, Claudia [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina)], E-mail: cavy3@hotmail.com; Limandri, Silvina [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina)], E-mail: silvilimandri@hotmail.com; Canafoglia, Maria Elena [Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge Ronco, Calle 47 No 257, 1900 La Plata, Argentina, Facultad de Ciencias Exactas y Facultad de Ingenieria de la UNLP, La Plata (Argentina); Bonetto, Rita [Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge Ronco, Calle 47 No 257, 1900 La Plata, Argentina, Facultad de Ciencias Exactas y Facultad de Ingenieria de la UNLP, La Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina)], E-mail: bonetto@quimica.unlp.edu.ar; Trincavelli, Jorge [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina)], E-mail: jorge@quechua.fis.uncor.edu

    2007-05-15

    The asymmetry of the characteristic X-ray peaks obtained using a Si(Li) detector is mainly due to incomplete charge collection. Impurities and defects in the crystalline structure of Si can act as 'traps' for holes and electrons in their trip toward the detector electrodes. Therefore, the collected charge, and consequently the detected energy, is smaller than the expected one. The global effect is that peaks may present a 'tail' toward the low energy side. This phenomenon is more important for low energies (lower than 2.3 keV, in the case of the detector characterized). In this work, the parameters related to peak asymmetry were studied, allowing a better understanding of the trapping process mentioned above. For this purpose, spectra from mono- and multi-element samples were collected for elements with atomic number between 7 and 20. In order to describe the shape of the characteristic K peaks as a function of its energy, an asymmetric correction to a Gaussian function was proposed. Spectra were obtained by electron probe microanalysis for incidence energies between 5 and 25 keV using an energy dispersive spectrometer equipped with an ultra-thin window Si(Li) detector. It was observed that the area corresponding to the asymmetric correction exhibits an energy dependence similar to that of the mass absorption coefficient of the detector material. In addition, other two spectrometers were used to investigate the dependence of tailing on the detection system. When two spectrometers with the same kind of detector and different pulse processors were compared, peaks were more asymmetric for lower peaking time values. When two different detectors were used, differences were even more important.

  4. 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.)

  5. Mapping the large area straw detectors of the COMPASS experiment with X-rays

    CERN Document Server

    Platzer, Klaus; Dünnweber, Wolfgang; Faessler, Martin A; Geyer, Reiner; Ilgner, C; Peshekhonov, Vladimir D; Wellenstein, Hermann

    2005-01-01

    In the COMPASS experiment at CERN, large straw drift tube detectors are used for large-angle tracking. To minimize the total areal density, a self supporting structure of thin-walled plastic tubes was chosen and, hence, a loss in mechanical precision was accepted. A complete mapping of the anode wire coordinate grid was required. An X-ray apparatus using a charge-coupled device (CCD) as imaging detector was built to investigate the mechanical properties and to calibrate (offline) the wire positions. Deviations of typically 200-400 mu m from the nominal positions, defined by equal spacing, are found across the detector area of 8 m/sup 2/. With a calibration method based on high-resolution CCD imaging and pattern recognition algorithms, the absolute wire coordinates are determined with an accuracy better than 30 mu m across the whole detector area. Temperature effects are clearly seen. Their inhomogenity limits the achievable accuracy to about 50 mu m under realistic experimental conditions, which is sufficient...

  6. Characterization of coplanar grid CZT detectors with highly collimated x-ray beam

    Science.gov (United States)

    Carini, Gabriella A.; Bolotnikov, Aleksey E.; Camarda, Giuseppe S.; Wright, Gomez W.; De Geronimo, Gianluigi; Siddons, D. P.; James, Ralph B.

    2004-10-01

    CdZnTe detectors demonstrated great potentials for detection of gamma radiation. However, energy resolution of CdZnTe detectors is significantly affected by uncollected holes which have low mobility and short lifetime. To overcome this deleterious effects upon energy resolution special detector designs have to be implemented. The most practical of them are the small pixel effect device, the co-planar grid device, and the virtual Frisch-grid device. We routinely use a highly collimated high-intensity X-ray beams provided by National Synchrotron Light Source (NSLS) facility at Brookhaven National Laboratory to study of CdZnTe material and performances of the different types of devices on the micron-scale. This powerful tool allows us to evaluate electronic properties of the material, device performance, uniformity of the detector responses, effects related to the device's contact pattern and electric field distribution, etc. In particular, in this paper we present new results obtained from the performance studies of 15 x 15 x 7.5 mm3 coplanar-grid devices coupled to readout ASIC. We observed the effect of the strip contacts comprising the grids on the energy resolution of the coplanar-grid device.

  7. Using Poisson statistics to analyze supernova remnant emission in the low counts X-ray regime

    Science.gov (United States)

    Roper, Quentin Jeffrey

    We utilize a Poisson likelihood in a maximum likelihood statistical analysis to analyze X-ray spectragraphic data. Specifically, we examine four extragalactic supernova remnants (SNR). IKT 5 (SNR 0047-73.5), IKT 25 (SNR 0104-72.3), and DEM S 128 (SNR 0103-72.4) which are designated as Type Ia in the literature due to their spectra and morphology. This is troublesome because of their asymmetry, a trait not usually associated with young Type Ia remnants. We present Chandra X-ray Observatory data on these three remnants, and perform a maximum likelihood analysis on their spectra. We find that the X-ray emission is dominated by interactions with the interstellar medium. In spite of this, we find a significant Fe overabundance in all three remnants. Through examination of radio, optical, and infrared data, we conclude that these three remnants are likely not "classical" Type Ia SNR, but may be examples of so-called "prompt" Type Ia SNR. We detect potential point sources that may be members of the progenitor systems of both DEM S 128 and IKT 5, which could suggest a new subclass of prompt Type Ia SNR, Fe-rich CC remnants. In addition, we examine IKT 18. This remnant is positionally coincident with the X-ray point source HD 5980. Due to an outburst in 1994, in which its brightness changed by 3 magnitudes (corrsponding to an increase in luminosity by a factor of 16) HD 5980 was classified as a luminous blue variable star. We examine this point source and the remnant IKT 18 in the X-ray, and find that its non-thermal photon index has decreased from 2002 to 2013, corresponding to a larger proportion of more energetic X-rays, which is unexpected.

  8. Characterization of CdTe Sensors with Schottky Contacts Coupled to Charge-Integrating Pixel Array Detectors for X-Ray Science

    CERN Document Server

    Becker, Julian; Shanks, Katherine S; Philipp, Hugh T; Weiss, Joel T; Purohit, Prafull; Chamberlain, Darol; Ruff, Jacob P C; Gruner, Sol M

    2016-01-01

    Pixel Array Detectors (PADs) consist of an x-ray sensor layer bonded pixel-by-pixel to an underlying readout chip. This approach allows both the sensor and the custom pixel electronics to be tailored independently to best match the x-ray imaging requirements. Here we present characterizations of CdTe sensors hybridized with two different charge-integrating readout chips, the Keck PAD and the Mixed-Mode PAD (MM-PAD), both developed previously in our laboratory. The charge-integrating architecture of each of these PADs extends the instantaneous counting rate by many orders of magnitude beyond that obtainable with photon counting architectures. The Keck PAD chip consists of rapid, 8-frame, in-pixel storage elements with framing periods $<$150 ns. The second detector, the MM-PAD, has an extended dynamic range by utilizing an in-pixel overflow counter coupled with charge removal circuitry activated at each overflow. This allows the recording of signals from the single-photon level to tens of millions of x-rays/...

  9. Research of x-ray nondestructive detector for high-speed running conveyor belt with steel wire ropes

    Science.gov (United States)

    Wang, Junfeng; Miao, Changyun; Wang, Wei; Lu, Xiaocui

    2008-03-01

    An X-ray nondestructive detector for high-speed running conveyor belt with steel wire ropes is researched in the paper. The principle of X-ray nondestructive testing (NDT) is analyzed, the general scheme of the X-ray nondestructive testing system is proposed, and the nondestructive detector for high-speed running conveyor belt with steel wire ropes is developed. The hardware of system is designed with Xilinx's VIRTEX-4 FPGA that embeds PowerPC and MAC IP core, and its network communication software based on TCP/IP protocol is programmed by loading LwIP to PowerPC. The nondestructive testing of high-speed conveyor belt with steel wire ropes and network transfer function are implemented. It is a strong real-time system with rapid scanning speed, high reliability and remotely nondestructive testing function. The nondestructive detector can be applied to the detection of product line in industry.

  10. High-Resolution Detector for At-Wavelength Metrology of X-Ray Optics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Since the launch of the first X-ray focusing telescope in 1963, the development of grazing incidence X-ray optics has been crucial to the development of the field of...

  11. High-Resolution Detector for At-Wavelength Metrology of X-Ray Optics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Since the launch of the first X-ray focusing telescope in 1963, the development of grazing incidence X-ray optics has been crucial to the development of the field...

  12. Hard X-ray texture measurements with an on-line image plate detector

    CERN Document Server

    Wcislak, L; Tschentscher, T; Klein, H; Bunge, H J

    2001-01-01

    An instrument for diffraction texture measurements in polycrystalline bulk materials using hard X-ray photons from the wiggler beamline BW5 at HASYLAB is described. High-energy photons in the 100 keV regime enable high penetration power in medium-to-high Z materials and the use of Laue diffraction geometry in combination with a two-dimensional area detector allows fast and convenient data collection. Determination of quantitative, high-resolution pole figures with a better angular resolution of 0.1 deg. is attained by the instrument. Profile analysis of the diffraction pattern parameters for each (h k l)-reflection thus provides, in addition to texture data, information about other microstructural quantities, e.g. lattice strain.

  13. Substrate and Passivation Techniques for Flexible Amorphous Silicon-Based X-ray Detectors

    Directory of Open Access Journals (Sweden)

    Michael A. Marrs

    2016-07-01

    Full Text Available Flexible active matrix display technology has been adapted to create new flexible photo-sensing electronic devices, including flexible X-ray detectors. Monolithic integration of amorphous silicon (a-Si PIN photodiodes on a flexible substrate poses significant challenges associated with the intrinsic film stress of amorphous silicon. This paper examines how altering device structuring and diode passivation layers can greatly improve the electrical performance and the mechanical reliability of the device, thereby eliminating one of the major weaknesses of a-Si PIN diodes in comparison to alternative photodetector technology, such as organic bulk heterojunction photodiodes and amorphous selenium. A dark current of 0.5 pA/mm2 and photodiode quantum efficiency of 74% are possible with a pixelated diode structure with a silicon nitride/SU-8 bilayer passivation structure on a 20 µm-thick polyimide substrate.

  14. Substrate and Passivation Techniques for Flexible Amorphous Silicon-Based X-ray Detectors.

    Science.gov (United States)

    Marrs, Michael A; Raupp, Gregory B

    2016-07-26

    Flexible active matrix display technology has been adapted to create new flexible photo-sensing electronic devices, including flexible X-ray detectors. Monolithic integration of amorphous silicon (a-Si) PIN photodiodes on a flexible substrate poses significant challenges associated with the intrinsic film stress of amorphous silicon. This paper examines how altering device structuring and diode passivation layers can greatly improve the electrical performance and the mechanical reliability of the device, thereby eliminating one of the major weaknesses of a-Si PIN diodes in comparison to alternative photodetector technology, such as organic bulk heterojunction photodiodes and amorphous selenium. A dark current of 0.5 pA/mm² and photodiode quantum efficiency of 74% are possible with a pixelated diode structure with a silicon nitride/SU-8 bilayer passivation structure on a 20 µm-thick polyimide substrate.

  15. Quantification of thin film crystallographic orientation using X-ray diffraction with an area detector.

    Science.gov (United States)

    Baker, Jessy L; Jimison, Leslie H; Mannsfeld, Stefan; Volkman, Steven; Yin, Shong; Subramanian, Vivek; Salleo, Alberto; Alivisatos, A Paul; Toney, Michael F

    2010-06-01

    As thin films become increasingly popular (for solar cells, LEDs, microelectronics, batteries), quantitative morphological and crystallographic information is needed to predict and optimize the film's electrical, optical, and mechanical properties. This quantification can be obtained quickly and easily with X-ray diffraction using an area detector in two sample geometries. In this paper, we describe a methodology for constructing complete pole figures for thin films with fiber texture (isotropic in-plane orientation). We demonstrate this technique on semicrystalline polymer films, self-assembled nanoparticle semiconductor films, and randomly packed metallic nanoparticle films. This method can be immediately implemented to help understand the relationship between film processing and microstructure, enabling the development of better and less expensive electronic and optoelectronic devices.

  16. Quantification of thin film crystallographic orientation using X-ray diffraction with an area detector

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Jessica L; Jimison, Leslie H; Mannsfeld, Stefan; Volkman, Steven; Yin, Shong; Subramanian, Vivek; Salleo, Alberto; Alivisatos, A Paul; Toney, Michael F

    2010-02-19

    As thin films become increasingly popular (for solar cells, LEDs, microelectronics, batteries), quantitative morphological information is needed to predict and optimize the film's electronic, optical and mechanical properties. This quantification can be obtained quickly and easily with X-ray diffraction using an area detector and synchrotron radiation in two simple geometries. In this paper, we describe a methodology for constructing complete pole figures for thin films with fiber texture (isotropic in-plane orientation). We demonstrate this technique on semicrystalline polymer films, self-assembled nanoparticle semiconductor films, and randomly-packed metallic nanoparticle films. This method can be immediately implemented to help understand the relationship between film processing and microstructure, enabling the development of better and less expensive electronic and optoelectronic devices.

  17. Radiation effects on the proportional counter X-ray detectors on board the NEAR spacecraft

    Energy Technology Data Exchange (ETDEWEB)

    Floyd, S.R. [NASA' s Goddard Space Flight Center, Laboratory for Extraterrestrial Physics, Greenbelt, MD 20771 (United States); Trombka, J.I. [NASA' s Goddard Space Flight Center, Laboratory for Extraterrestrial Physics, Greenbelt, MD 20771 (United States); Leidecker, H.W. [NASA' s Goddard Space Flight Center, Laboratory for Extraterrestrial Physics, Greenbelt, MD 20771 (United States); Clark, P.E. [The Catholic University of America, Washington, DC 20064 (United States); Starr, R. [The Catholic University of America, Washington, DC 20064 (United States); Goldsten, J.O. [Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States); Roth, D.R. [Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States)

    1999-02-11

    The X-ray proportional counters on board the Near Earth Asteroid Rendezvous (NEAR) spacecraft have exhibited a resolution degradation and recovery phenomenon several times during the long cruise phase of the mission. The resolution is checked periodically by commanding an {sup 55}Fe source into the window area. The degradation is seen as a low energy tailing of the 5.9 keV photopeak. Two events have occurred which provided good spectral data for better understanding the degradation phenomenon. In November 1997 a large solar particle event occurred that degraded the resolution and excited copper in the collimator. Eventually the detectors returned to normal. In January 1998 the spacecraft performed an Earth swingby gravity assist maneuver. The near Earth environment excited the magnesium and aluminum in the filter elements. The copper line was also produced. The NEAR spacecraft was launched in February 1996 and will rendezvous and orbit the asteroid 433 Eros in early 1999.

  18. Substrate and Passivation Techniques for Flexible Amorphous Silicon-Based X-ray Detectors

    Science.gov (United States)

    Marrs, Michael A.; Raupp, Gregory B.

    2016-01-01

    Flexible active matrix display technology has been adapted to create new flexible photo-sensing electronic devices, including flexible X-ray detectors. Monolithic integration of amorphous silicon (a-Si) PIN photodiodes on a flexible substrate poses significant challenges associated with the intrinsic film stress of amorphous silicon. This paper examines how altering device structuring and diode passivation layers can greatly improve the electrical performance and the mechanical reliability of the device, thereby eliminating one of the major weaknesses of a-Si PIN diodes in comparison to alternative photodetector technology, such as organic bulk heterojunction photodiodes and amorphous selenium. A dark current of 0.5 pA/mm2 and photodiode quantum efficiency of 74% are possible with a pixelated diode structure with a silicon nitride/SU-8 bilayer passivation structure on a 20 µm-thick polyimide substrate. PMID:27472329

  19. Active Detectors for Plasma Soft X-Ray Detection at PALS

    Directory of Open Access Journals (Sweden)

    C. Granja

    2010-01-01

    Full Text Available This paper summarizes the work carried out for an experimental study of low-energy nuclear excitation by laser-produced plasma at the PALS Prague laser facility. We describe the adaptation and shielding of single-quantum active radiation detectors developed at IEAP CTU Prague to facilitate their operation inside the laser interaction chamber in the vicinity of the plasma target. The goal of this effort is direct real-time single-quantum detection of plasma soft X-ray radiation with energy above a few keV and subsequent identification of the decay of the excited nuclear states via low-energy gamma rays in a highly radiative environment with strong electromagnetic interference.

  20. Performance and applications of GaAs:Cr-based Medipix detector in X-ray CT

    Science.gov (United States)

    Kozhevnikov, D.; Chelkov, G.; Demichev, M.; Gridin, A.; Smolyanskiy, P.; Zhemchugov, A.

    2017-01-01

    In the recent years, the method of single photon counting X-ray μ-CT is being actively developed and applied in various fields. Results of our studies carried out using the MARS μ-CT scanner equipped with GaAs Medipix-based camera are presented. The procedure of mechanical alignment of the scanner is described, including direct and indirect measurements of the spatial resolution. The software chain for data processing and reconstruction has been developed and reported. We demonstrate the possibility to apply the scanner for research in geology and medicine and provide demo images of geological samples (chrome spinellids, titanium magnetite ore) and medical samples (atherosclerotic plaque, abdominal aortic aneurysm). The first results of multi-energy scans using GaAs:Cr-based camera are shown.

  1. 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.

  2. Pulsed X-ray radiography of a gas jet target for laser-matter interaction experiments with the use of a CCD detector

    Energy Technology Data Exchange (ETDEWEB)

    Rakowski, R. [Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Street, 00-908 Warsaw (Poland); Bartnik, A. [Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Street, 00-908 Warsaw (Poland); Fiedorowicz, H. [Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Street, 00-908 Warsaw (Poland)]. E-mail: hfiedorowicz@wat.edu.pl; Jarocki, R. [Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Street, 00-908 Warsaw (Poland); Kostecki, J. [Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Street, 00-908 Warsaw (Poland); MikoIajczyk, J. [Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Street, 00-908 Warsaw (Poland); Szczurek, A. [Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Street, 00-908 Warsaw (Poland); Szczurek, M. [Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Street, 00-908 Warsaw (Poland); Foeldes, I.B. [KFKI-Research Institute for Particle and Nuclear Physics, Association EURATOM, P.O. Box 49, H-1525 Budapest (Hungary); Toth, Zs. [Department of Optics and Quantum Electronics, University of Szeged, H-6701 Szeged, Pf.: 406 (Hungary)

    2005-10-01

    Characterization of gas jet targets has been carried out using pulsed X-ray radiography. A laser-plasma X-ray source was applied for backlighting of the targets to obtain X-ray shadowgraphs registered with a CCD detector. From the shadowgraphs, characteristics of the targets were determined.

  3. 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

  4. Fast scintillation timing detector using proportional-mode avalanche photodiode for nuclear resonant scattering experiments in high-energy synchrotron X-ray region

    Science.gov (United States)

    Inoue, Keisuke; Kishimoto, Shunji

    2016-01-01

    To obtain both a high count rate of >107 s-1 and a detection efficiency sufficient for high-energy X-rays of >30 keV, we propose a scintillation timing detector using a proportional-mode silicon avalanche photodiode (Si-APD) for synchrotron radiation nuclear resonant scattering. We here present results obtained with a prototype detector using a lead-loaded plastic scintillator (EJ-256) mounted on a proportional-mode Si-APD (active area size: 3 mm in diameter). The detector was operated at ‒35 °C for a better signal-to-noise ratio. Using synchrotron X-rays of 67.41 keV, which is the same energy as the first excited level of 61Ni, we successfully measured pulse-height and time spectra of the scintillation light. A good time resolution of 0.50±0.06 ns (full width at half-maximum) was obtained for 67.41 keV X-rays with a scintillator 3 mm in diameter and 2 mm thick.

  5. A Micromegas-based low-background x-ray detector coupled to a slumped-glass telescope for axion research

    DEFF Research Database (Denmark)

    Aznar, F.; Castel, J.; Christensen, F. E.

    2015-01-01

    -approximation Wolter I x-ray telescope (XRT) assembled from thermally-formed (or "slumped") glass substrates deposited with multilayer coatings. The system has been conceived as a technological pathfinder for the future International Axion Observatory (IAXO), as it combines two of the techniques (optic and detector......) proposed in the conceptual design of the project. It is innovative for two reasons: it is the first time an x-ray optic has been designed and fabricated specifically for axion research, and the first time a Micromegas detector has been operated with an x-ray optic. The line has been installed at one end...... of the CERN Axion Solar Telescope (CAST) magnet and is currently looking for solar axions. The combination of the XRT and Micromegas detector provides the best signal-to-noise ratio obtained so far by any detection system of the CAST experiment with a background rate of 5.4×10−3 counts per hour in the energy...

  6. 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.

  7. Count rates and structure factors in anomalous soft x-ray scattering from cuprate superconductors

    NARCIS (Netherlands)

    Abbamonte, P; Rusydi, A; Logvenov, G; Bozovic, [No Value; Sawatzky, GA; Venema, L.C.; Bozovic,; Pavuna, D

    2002-01-01

    It has recently been shown that x-ray diffraction from the doped holes in cuprates can be enhanced by 3-4 orders of magnitude by exploiting resonance effects in the oxygen K shell. This new type of anomalous scattering is direct way of probing ground state inhomogeneity in the mobile carrier liquid

  8. Note: significant increase to the temporal resolution of 2D X-ray detectors using a novel beam chopper system.

    Science.gov (United States)

    Küchemann, Stefan; Mahn, Carsten; Samwer, Konrad

    2014-01-01

    The investigation of short time dynamics using X-ray scattering techniques is commonly limited either by the read out frequency of the detector or by a low intensity. In this paper, we present a chopper system, which can increase the temporal resolution of 2D X-ray detectors by a factor of 13. This technique only applies to amorphous or polycrystalline samples due to their circular diffraction patterns. Using the chopper, we successfully increased the temporal resolution up to 5.1 ms during synchrotron experiments. For the construction, we provide a mathematical formalism, which, in principle, allows an even higher increase of the temporal resolution.

  9. The hard X-ray response of epitaxial GaAs detectors

    CERN Document Server

    Owens, A; Kraft, S; Peacock, A; Nenonen, S; Andersson, H

    2000-01-01

    We report on hard X-ray measurements with two epitaxial GaAs detectors of active areas 2.22 mm sup 2 and thicknesses 40 and 400 mu m at the ESRF and HASYLAB synchrotron research facilities. The detectors were fabricated using high-purity material and in spite of an order of magnitude difference in depletion depths, they were found to have comparable performances with energy resolutions at -45 deg. C of approx 1 keV fwhm at 7 keV rising to approx 2 keV fwhm at 200 keV and noise floors in the range 1-1.5 keV. At energies <30 keV, the energy resolution was dominated by leakage current and electromagnetic pick-up, while at the highest energies measured, the resolutions approach the expected Fano limit (e.g., approx 1 keV near 200 keV). Both detectors are remarkably linear, with average rms non-linearities of 0.2% over the energy range 10-60 keV, which, taken in conjunction with Monte-Carlo results indicate that charge collection efficiencies must be in excess of 98%. This is consistent with material science me...

  10. The Speedster-EXD- A New Event-Driven Hybrid CMOS X-ray Detector

    Science.gov (United States)

    Griffith, Christopher V.; Falcone, Abraham D.; Prieskorn, Zachary R.; Burrows, David N.

    2016-01-01

    The Speedster-EXD is a new 64×64 pixel, 40-μm pixel pitch, 100-μm depletion depth hybrid CMOS x-ray detector with the capability of reading out only those pixels containing event charge, thus enabling fast effective frame rates. A global charge threshold can be specified, and pixels containing charge above this threshold are flagged and read out. The Speedster detector has also been designed with other advanced in-pixel features to improve performance, including a low-noise, high-gain capacitive transimpedance amplifier that eliminates interpixel capacitance crosstalk (IPC), and in-pixel correlated double sampling subtraction to reduce reset noise. We measure the best energy resolution on the Speedster-EXD detector to be 206 eV (3.5%) at 5.89 keV and 172 eV (10.0%) at 1.49 keV. The average IPC to the four adjacent pixels is measured to be 0.25%±0.2% (i.e., consistent with zero). The pixel-to-pixel gain variation is measured to be 0.80%±0.03%, and a Monte Carlo simulation is applied to better characterize the contributions to the energy resolution.

  11. The Speedster-EXD- A New Event-Driven Hybrid CMOS X-ray Detector

    CERN Document Server

    Griffith, Christopher V; Prieskorn, Zachary R; Burrows, David N

    2016-01-01

    The Speedster-EXD is a new 64x64 pixel, 40 $\\mu$m pixel pitch, 100 $\\mu$m depletion depth hybrid CMOS X-ray detector (HCD) with the capability of reading out only those pixels containing event charge, thus enabling fast effective frame rates. A global charge threshold can be specified, and pixels containing charge above this threshold are flagged and read out. The Speedster detector has also been designed with other advanced in-pixel features to improve performance, including a low-noise, high-gain CTIA amplifier that eliminates interpixel capacitance crosstalk (IPC), and in-pixel Correlated Double Sampling (CDS) subtraction to reduce reset noise. We measure the best energy resolution on the Speedster-EXD detector to be 206 eV (3.5 %) at 5.89 keV and 172 eV (10.0 %) at 1.49 keV. The average IPC to the four adjacent pixels is measured to be 0.25 $\\pm$ 0.2 % (i.e. consistent with zero). The pixel-to-pixel gain variation is measured to be 0.80 $\\pm$ 0.03 %, and a Monte Carlo simulation is applied to better chara...

  12. Comparison of X-ray detectors for a diffraction enhanced imaging system

    CERN Document Server

    Kiss, M Z; Zhong Zhon

    2002-01-01

    Three digital detector systems--a Fuji BAS2500 Image Plate Reader, a prototype charge-coupled device (CCD) from Mar USA and the MicroPhotonics XQUIS 1000 were compared with respect to format, dynamic range, dark noise, and spatial resolution. Experiments were conducted using highly collimated monochromatic X-rays at 20 keV, produced at the National Synchrotron Light Source. This study characterized digital detectors being considered for integration into a synchrotron-based diffraction enhanced imaging (DEI) apparatus used for medical imaging research, particularly mammography. These detectors are also being considered for integration into a proposed clinical prototype for DEI-based mammography. While all three systems had comparable image quality, the CCDs had faster readout time than the image plate system. However, the Fuji system had the largest dynamic range (approx 10 sup 5 compared to 10 sup 4 for CCDs) and the largest active area. The MicroPhotonics XQUIS 1000 had the best spatial resolution as charact...

  13. A multielement Ge detector with complete spectrum readout for x-ray fluorescence microprobe and microspectroscopy (abstract)

    Science.gov (United States)

    Rivers, Mark L.; Sutton, Stephen R.; Rarback, Harvey

    1995-02-01

    Multielement Ge and Si(Li) detectors have been used in recent years to improve the increase count rate capability and to improve the solid-angle efficiency in fluorescence x-ray absorption spectroscopy (XAS). Such systems have typically been equipped with one or more single-channel analyzers (SCAs) for each detector element. Such SCA-based electronics are sufficient when only the counts in one or two well-resolved peaks are of interest. For the fluorescence (XRF) microprobe at beamline X-26A at the NSLS, SCA-based electronics were not a satisfactory solution for two reasons: (1) for XRF experiments, the entire fluorescence spectrum is required; (2) for micro-XAS studies of trace elements in complex systems, the fluorescence peak often sits on a significant background or partially overlaps another fluorescence peak, requiring software background subtraction or peak deconvolution. An electronics system which permits collection of the entire fluorescence spectrum from each detector element has been designed. The system is made cost-effective by the use of analog multiplexors, reducing the number of analog-to-digital converters (ADCs) and multichannel analyzers (MCAs) required. The system was manufactured by Canberra Industries and consists of: (1) a 13 element Ge detector (11 mm diameter detector elements), (2) 13 NIM spectroscopy amplifiers with programmable gains, (3) four analog multiplexors with maximum of eight inputs each, (4) four ADCs with programmable offsets and gains and 800 ns conversion time, and (5) two MCAs with Ethernet communications ports and two ADC inputs each. The amplifiers have shaping times which are adjustable from 0.5 to 12 μs. The analog multiplexors were modified to perform pileup rejection. The analog multiplexing does not significantly reduce the count rate capability of the system, even at the shortest amplifier shaping times. The average detector resolution is 170 eV at 12 μs shaping time and 200 eV at 4 μs shaping time. The maximum

  14. Search for chameleons with an InGrid based X-ray detector at the CAST experiment

    Energy Technology Data Exchange (ETDEWEB)

    Desch, Klaus; Kaminski, Jochen; Krieger, Christoph; Schmidt, Sebastian [Physikalisches Institut, Universitaet Bonn, Nussallee 12, 53115 Bonn (Germany)

    2016-07-01

    The CERN Axion Solar Telescope (CAST) searches for axions and also other exotic particles emerging from the Sun. Chameleons, for example, are part of Dark Energy theories. Like Axions they can be converted into soft X-ray photons in a high magnetic field and should result in an X-ray spectrum peaking below 1 keV. Because of their low energy and weak coupling, detectors with low energy threshold and low background rates are mandatory. Both requirements are met by an X-ray detector based on the combination of a Micromegas gas amplification stage with a highly integrated pixel chip which allows to make full use of the Micromegas structure's granularity. It has been demonstrated that these devices can detect even single electrons. Thus, allowing for a topological background suppression as well as for detection of low energy X-ray photons creating only very few primary electrons. After the detection threshold had been evaluated to be low enough to allow for the detection of the carbon K{sub α} line at 277 eV, the detector was mounted at one of CAST's X-ray telescopes and installed along with its infrastructure in 2014. During data taking until end of 2015 background rates of less than 10{sup -4} keV/(cm{sup 2}.s) have been achieved below 2 keV. First preliminary results of the ongoing chameleon analysis and possibly an improved limit for solar chameleons are presented.

  15. Characterization of a Prototype TES-Based Anti-coincidence Detector for Use with Future X-ray Calorimeter Arrays

    Science.gov (United States)

    Busch, S. E.; Yoon, W. S.; Adams, J. S.; Bailey, C. N.; Bandler, S. R.; Chervenak, J. A.; Eckart, M. E.; Ewin, A. J.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Lee, S.-J.; Porst, J.-P.; Porter, F. S.; Sadleir, J. E.; Smith, S. J.; Sultana, M.

    2016-07-01

    For future X-ray observatories utilizing transition-edge sensor (TES) microcalorimeters, an anti-coincidence detector (anti-co) is required to discriminate X-ray (˜ 0.1-10 keV) signals from non-X-ray background events, such as ionizing particles. We have developed a prototype anti-co that utilizes TESs, which will be compatible with the TES focal-plane arrays planned for future X-ray observatories. This anti-co is based upon the cryogenic dark matter search II detector design. It is a silicon wafer covered with superconducting collection fins and TES microcalorimeters. Minimum ionizing particles deposit energy while passing through the silicon. The athermal phonons produced by these events are absorbed in the superconducting fins, breaking Cooper pairs. The resulting quasiparticles diffuse along the superconducting fin, producing a signal when they reach the TES. By determining a correlation between detections in the anti-co and the X-ray detector one can identify and flag these background events. We have fabricated and tested a single-channel prototype anti-co device on a 1.5 × 1.9 cm^2 chip. We have measured the signals in this device from photons of several energies between 1.5 and 60 keV, as well as laboratory background events, demonstrating a threshold ˜ 100 times lower than is needed to detect minimum ionizing particles.

  16. The Nustar Extragalactic Surveys: The Number Counts of Active Galactic Nuclei and the Resolved Fraction of the Cosmic X-Ray Background

    DEFF Research Database (Denmark)

    Harrison, F. A.; Aird, J.; Civano, F.;

    2016-01-01

    cm-2 ≤ 10-12, a factor ∼100 fainter than previous measurements. The 8–24 keV number counts match predictions from AGN populationsynthesis models, directly confirming the existence of a population of obscured and/or hard X-ray sources inferredfrom the shape of the integrated cosmic X-ray background...

  17. Infrared LED Enhanced Spectroscopic CdZnTe Detector Working under High Fluxes of X-rays

    Directory of Open Access Journals (Sweden)

    Jakub Pekárek

    2016-09-01

    Full Text Available This paper describes an application of infrared light-induced de-polarization applied on a polarized CdZnTe detector working under high radiation fluxes. We newly demonstrate the influence of a high flux of X-rays and simultaneous 1200-nm LED illumination on the spectroscopic properties of a CdZnTe detector. CdZnTe detectors operating under high radiation fluxes usually suffer from the polarization effect, which occurs due to a screening of the internal electric field by a positive space charge caused by photogenerated holes trapped at a deep level. Polarization results in the degradation of detector charge collection efficiency. We studied the spectroscopic behavior of CdZnTe under various X-ray fluxes ranging between 5 × 10 5 and 8 × 10 6 photons per mm 2 per second. It was observed that polarization occurs at an X-ray flux higher than 3 × 10 6 mm − 2 ·s − 1 . Using simultaneous illumination of the detector by a de-polarizing LED at 1200 nm, it was possible to recover X-ray spectra originally deformed by the polarization effect.

  18. Infrared LED Enhanced Spectroscopic CdZnTe Detector Working under High Fluxes of X-rays.

    Science.gov (United States)

    Pekárek, Jakub; Dědič, Václav; Franc, Jan; Belas, Eduard; Rejhon, Martin; Moravec, Pavel; Touš, Jan; Voltr, Josef

    2016-09-27

    This paper describes an application of infrared light-induced de-polarization applied on a polarized CdZnTe detector working under high radiation fluxes. We newly demonstrate the influence of a high flux of X-rays and simultaneous 1200-nm LED illumination on the spectroscopic properties of a CdZnTe detector. CdZnTe detectors operating under high radiation fluxes usually suffer from the polarization effect, which occurs due to a screening of the internal electric field by a positive space charge caused by photogenerated holes trapped at a deep level. Polarization results in the degradation of detector charge collection efficiency. We studied the spectroscopic behavior of CdZnTe under various X-ray fluxes ranging between 5 × 10 5 and 8 × 10 6 photons per mm 2 per second. It was observed that polarization occurs at an X-ray flux higher than 3 × 10 6 mm - 2 ·s - 1 . Using simultaneous illumination of the detector by a de-polarizing LED at 1200 nm, it was possible to recover X-ray spectra originally deformed by the polarization effect.

  19. Response of a CsI/amorphous-Si flat panel detector as function of incident x-ray angle

    Science.gov (United States)

    Tkaczyk, J. Eric; Claus, Bernhard; Trotter, Dinko Gonzalez; Eberhard, J. W.

    2006-03-01

    Two mechanisms for MTF dependence on incident x-ray angle are demonstrated by an experimental technique that separates the two phenomena. The dominant effect is that travel of x-ray photons through the scintillator at non-normal incidence involves an in-plane component. This mechanism leads to a significant but deterministic blurring of the incident image, but has no effect on the noise transfer characteristics of the detector. A secondary effect is that at large angles to the surface normal, x-ray-to-optical conversion occurs at positions in the scintillator further away from the photodiode surface. This leads to a small net decrease in MTF and NPS at angles above 60 degrees. The deterministic character of the angular dependence of gain, MTF and NPS leads to the conclusion that sufficient angular range can be supported by this detector construction. Excellent functionality in the context of tomography is expected.

  20. Application of the HOTWAXS detector for imaging at higher X-ray energies (10-30 keV)

    Energy Technology Data Exchange (ETDEWEB)

    Bateman, J.E. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (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; Harvey, I.; Helsby, W.I. [Science and Technology Facilities Council, Daresbury Laboratory, Keckwick Lane, Daresbury, Warrington WA4 4AD (United Kingdom); Spill, E.J. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom)

    2009-06-01

    The high overall throughput wide angle X-ray scattering (HOTWAXS) gas detector system, aimed at X-ray diffraction (XRD) and wide angle X-ray scattering (WAXS) applications has been a successful user facility on stations 2.1 and 9.3 at the Daresbury SRS offering high-speed data acquisition. The facility has been duplicated on station I22 of the Diamond light source. The energy range covered by stations I22 and 9.3 is very similar varying from 6 to 30 keV, well above the energy range conventionally covered by gas detectors. Here, we report studies of the options for successful operation of HOTWAXS at the upper end of this energy range, made possible by this particular design.

  1. X-ray absorption spectroscopy of diluted system by undulator photon source and multi-element solid-state detector

    CERN Document Server

    Tanida, H

    2001-01-01

    In order to measure the extended X-ray absorption fine structure (EXAFS) spectrum of an ultra-diluted system, an optics and detector control system for a synchrotron radiation beamline is developed. The undulator gap width is continuously tuned to obtain the maximum X-ray photon flux during the energy scan for the EXAFS measurement. A piezoelectric translator optimizes the parallelism of the double crystal in a monochromator at each measurement point to compensate for mechanical errors of the monochromator, resulting in a smooth and intense X-ray photon flux during the measurement. For a detection of a weak fluorescence signal from diluted samples, a 19-element solid-state detector and digital signal processor are used. A K-edge EXAFS spectrum of iron in a myoglobin aqueous solution with a concentration of 5.58 parts per million was obtained by this system.

  2. Gallium Arsenide detectors for X-ray and electron (beta particle) spectroscopy

    Science.gov (United States)

    Lioliou, G.; Barnett, A. M.

    2016-11-01

    Results characterizing GaAs p+-i-n+ mesa photodiodes with a 10 μm i layer for their spectral response under illumination of X-rays and beta particles are presented. A total of 22 devices, having diameters of 200 μm and 400 μm, were electrically characterized at room temperature. All devices showed comparable characteristics with a measured leakage current ranging from 4 nA/cm2 to 67 nA/cm2 at an internal electric field of 50 kV/cm. Their unintentionally doped i layers were found to be almost fully depleted at 0 V due to their low doping density. 55Fe X-ray spectra were obtained using one 200 μm diameter device and one 400 μm diameter device. The best energy resolution (FWHM at 5.9 keV) achieved was 625 eV using the 200 μm and 740 eV using the 400 μm diameter device, respectively. Noise analysis showed that the limiting factor for the energy resolution of the system was the dielectric noise; if this noise was eliminated by better design of the front end of the readout electronics, the achievable resolution would be 250 eV. 63Ni beta particle spectra obtained using the 200 μm diameter device showed the potential utility of these detectors for electron and beta particle detection. The development of semiconductor electron spectrometers is important particularly for space plasma physics; such devices may find use in future space missions to study the plasma environment of Jupiter and Europa and the predicted electron impact excitation of water vapor plumes from Europa hypothesized as a result of recent Hubble Space Telescope (HST) UV observations.

  3. Finding Rare AGN: X-ray Number Counts of Chandra Sources in Stripe 82

    CERN Document Server

    LaMassa, Stephanie M; Glikman, Eilat; Cappelluti, Nico; Civano, Francesca; Comastri, Andrea; Treister, Ezequiel; Arifin,; Boehringer, Hans; Cardamone, Carie; Chon, Gayoung; Kephart, Miranda; Murray, Stephen S; Richards, Gordon; Ross, Nic; Rozner, Joshua S; Schawinski, Kevin

    2012-01-01

    We present the first results of a wide area X-ray survey within the Sloan Digital Sky Survey (SDSS) Stripe 82, a 300 deg$^2$ region of the sky with a substantial investment in multi-wavelength coverage. We analyzed archival {\\it Chandra} observations that cover 7.5 deg$^2$ within Stripe 82 ("Stripe 82 ACX"), reaching 4.5$\\sigma$ flux limits of 7.9$\\times10^{-16}$, 3.4$\\times10^{-15}$ and 1.8$\\times10^{-15}$ erg s$^{-1}$ cm$^{-2}$ in the soft (0.5-2 keV), hard (2-7 keV) and full (0.5-7 keV) bands, to find 774, 239 and 1118 X-ray sources, respectively. Three hundred twenty-one sources are detected only in the full band and 9 sources are detected solely in the soft band. Utilizing data products from the {\\it Chandra} Source Catalog, we construct independent Log$N$-Log$S$ relationships, detailing the number density of X-ray sources as a function of flux, which show general agreement with previous {\\it Chandra} surveys. We compare the luminosity distribution of Stripe 82 ACX with the smaller, deeper CDF-S + E-CDFS...

  4. Anti-scatter grid artifact elimination for high resolution x-ray imaging CMOS detectors

    Science.gov (United States)

    Rana, R.; Singh, V.; Jain, A.; Bednarek, D. R.; Rudin, S.

    2015-03-01

    Higher resolution in dynamic radiological imaging such as angiography is increasingly being demanded by clinicians; however, when standard anti-scatter grids are used with such new high resolution detectors, grid-line artifacts become more apparent resulting in increased structured noise that may overcome the contrast signal improvement benefits of the scatter-reducing grid. Although grid-lines may in theory be eliminated by dividing the image of a patient taken with the grid by a flat-field image taken with the grid obtained prior to the clinical image, unless the remaining additive scatter contribution is subtracted in real-time from the dynamic clinical image sequence before the division by the reference image, severe grid-line artifacts may remain. To investigate grid-line elimination, a stationary Smit Röntgen X-ray grid (line density: 70 lines/cm, grid ratio 13:1) was used with both a 75 micron-pixel CMOS detector and a standard 194 micron-pixel flat panel detector (FPD) to image an artery block insert placed in a modified uniform frontal head phantom for a 20 x 20cm FOV (approximately). Contrast and contrast-to-noise ratio (CNR) were measured with and without scatter subtraction prior to grid-line correction. The fixed pattern noise caused by the grid was substantially higher for the CMOS detector compared to the FPD and caused a severe reduction of CNR. However, when the scatter subtraction corrective method was used, the removal of the fixed pattern noise (grid artifacts) became evident resulting in images with improved CNR.

  5. Application of the Monte Carlo method to analyze materials used in flat panel detectors to obtain X-ray spectra

    Science.gov (United States)

    Gallardo, Sergio; Pozuelo, Fausto; Querol, Andrea; Ródenas, José; Verdú, Gumersindo

    2014-06-01

    An accurate knowledge of the photon spectra emitted by X-ray tubes in radiodiagnostic is essential to better estimate the imparted dose to patients and to improve the quality image obtained with these devices. In this work, it is proposed the use of a flat panel detector together with a PMMA wedge to estimate the actual X-ray spectrum using the Monte Carlo method and unfolding techniques. The MCNP5 code has been used to model different flat panels (based on indirect and direct methods to produce charge carriers from absorbed X-rays) and to obtain the dose curves and system response functions. Most of the actual flat panel devices use scintillator materials that present K-edge discontinuities in the mass energy-absorption coefficient, which strongly affect the response matrix. In this paper, the applicability of different flat panels for reconstructing X-ray spectra is studied. The effect of the mass energy-absorption coefficient of the scintillator material has been studied on the response matrix and consequently, in the reconstructed spectra. Different unfolding methods are tested to reconstruct the actual X-ray spectrum knowing the dose curve and the response function. It has been concluded that the regularization method MTSVD is appropriate to unfold X-ray spectra in all the scintillators studied.

  6. A diffracted-beam monochromator for long linear detectors in X-ray diffractometers with Bragg-Brentano parafocusing geometry

    NARCIS (Netherlands)

    Van der Pers, N.M.; Hendrikx, R.W.A.; Delhez, R.; Böttger, A.J.

    2013-01-01

    A new diffracted-beam monochromator has been developed for Bragg-Brentano X-ray diffractometers equipped with a linear detector. The monochromator consists of a cone-shaped graphite highly oriented pyrolytic graphite crystal oriented out of the equatorial plane such that the parafocusing geometry is

  7. Development of a DAQ system for a plasma display panel-based X-ray detector (PXD)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hakjae [School of Biomedical Engineering, Korea University, Seoul (Korea, Republic of); Research Institute of Health Science, Korea University, Seoul (Korea, Republic of); Jung, Young-Jun [School of Biomedical Engineering, Korea University, Seoul (Korea, Republic of); Eom, Sangheum [Plasma Technology Research Center, National Fusion Research Institute, Gunsan-si (Korea, Republic of); Kang, Jungwon [Department of Electronics and Electrical Engineering, Dankook University, Yongin, Gyeonggi (Korea, Republic of); Lee, Kisung, E-mail: kisung@korea.ac.kr [School of Biomedical Engineering, Korea University, Seoul (Korea, Republic of)

    2015-06-01

    Recently, a novel plasma display panel (PDP)-based X-ray detector (PXD) was developed. The goal of this study is to develop a data acquisition system for use with the PXD as an imaging detector. Since the prototype detector does not have any barrier ribs or a switching device in a detector pixel, a novel pixelation scheme—the line-scan method—is developed for this new detector. To implement line scanning, a multichannel high-voltage switching circuit and a multichannel charge-acquisition circuit are developed. These two circuits are controlled by an FPGA-based digital signal processing board, from which the information about the charge and position of each pixel can be sent to a PC. FPGA-based baseline compensation and switching noise rejection algorithms are used to improve the signal-to-noise ratio (SNR). The characteristic curve of the entire PXD system is acquired, and the correlation coefficients between the X-ray dose, and the signal intensity and the SNR were determined to be approximately 0.99 and 52.9, respectively. - Highlights: • We developed a data acquisition circuit for a novel X-ray imaging detector. • Line scan, noise rejection, and data transmission methods have been implemented by the FPGA. • The linearity and SNR of the proposed detector system have been measured quantitatively.

  8. Modeling and characterization of X-ray yield in a polychromatic, lab-scale, X-ray computed tomography system

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, J.C.E.; Chawla, Nikhilesh, E-mail: nchawla@asu.edu

    2015-05-21

    A modular X-ray computed micro-tomography (µXCT) system is characterized in terms of X-ray yield resulting both from the generated X-ray spectrum and from X-ray detection with an energy-sensitive detector. The X-ray computed tomography system is composed of a commercially available cone-beam microfocus X-ray source and a modular optically-coupled-CCD-scintillator X-ray detector. The X-ray yield is measured and reported in units independent from exposure time, X-ray tube beam target current, and cone-beam-to-detector geometry. The polychromatic X-ray source is modeled as a broad Bremsstrahlung X-ray spectrum in order to understand the effect of the controllable parameters, that is, X-ray tube accelerating voltage and X-ray beam filtering. An approach is adopted which expresses the absolute number of emitted X-rays. The response of the energy-sensitive detector to the modeled spectrum is modeled as a function of scintillator composition and thickness. The detection efficiency model for the polychromatic X-ray detector considers the response of the light collection system and the electronic imaging array in order to predict absolute count yield under the studied conditions. The modeling approach is applied to the specific hardware implemented in the current µXCT system. The model's predictions for absolute detection rate are in reasonable agreement with measured values under a range of conditions applied to the system for X-ray microtomography imaging, particularly for the LuAG:Ce scintillator material.

  9. Toward Low-Voltage and Bendable X-Ray Direct Detectors Based on Organic Semiconducting Single Crystals.

    Science.gov (United States)

    Ciavatti, Andrea; Capria, Ennio; Fraleoni-Morgera, Alessandro; Tromba, Giuliana; Dreossi, Diego; Sellin, Paul J; Cosseddu, Piero; Bonfiglio, Annalisa; Fraboni, Beatrice

    2015-11-25

    Organic materials have been mainly proposed as ionizing radiation detectors in the indirect conversion approach. The first thin and bendable X-ray direct detectors are realized (directly converting X-photons into an electric signal) based on organic semiconducting single crystals that possess enhanced sensitivity, low operating voltage (≈5 V), and a minimum detectable dose rate of 50 μGy s(-1) .

  10. 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.

  11. Monte Carlo simulation of the response functions of Cd Te detectors to be applied in X-rays spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tomal, A. [Universidade Federale de Goias, Instituto de Fisica, Campus Samambaia, 74001-970, Goiania, (Brazil); Lopez G, A. H.; Santos, J. C.; Costa, P. R., E-mail: alessandra_tomal@yahoo.com.br [Universidade de Sao Paulo, Instituto de Fisica, Rua du Matao Travessa R. 187, Cidade Universitaria, 05508-090 Sao Paulo (Brazil)

    2014-08-15

    In this work, the energy response functions of a Cd Te detector were obtained by Monte Carlo simulation in the energy range from 5 to 150 keV, using the Penelope code. The response functions simulated included the finite detector resolution and the carrier transport. The simulated energy response matrix was validated through comparison with experimental results obtained for radioactive sources. In order to investigate the influence of the correction by the detector response at diagnostic energy range, x-ray spectra were measured using a Cd Te detector (model Xr-100-T, Amptek), and then corrected by the energy response of the detector using the stripping procedure. Results showed that the Cd Te exhibit good energy response at low energies (below 40 keV), showing only small distortions on the measured spectra. For energies below about 70 keV, the contribution of the escape of Cd- and Te-K x-rays produce significant distortions on the measured x-ray spectra. For higher energies, the most important correction is the detector efficiency and the carrier trapping effects. The results showed that, after correction by the energy response, the measured spectra are in good agreement with those provided by different models from the literature. Finally, our results showed that the detailed knowledge of the response function and a proper correction procedure are fundamental for achieve more accurate spectra from which several qualities parameters (i.e. half-value layer, effective energy and mean energy) can be determined. (Author)

  12. Monte Carlo semi-empirical model for Si(Li) x-ray detector: Differences between nominal and fitted parameters

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Pino, N.; Padilla-Cabal, F.; Garcia-Alvarez, J. A.; Vazquez, L.; D' Alessandro, K.; Correa-Alfonso, C. M. [Departamento de Fisica Nuclear, Instituto Superior de Tecnologia y Ciencias Aplicadas (InSTEC) Ave. Salvador Allende y Luaces. Quinta de los Molinos. Habana 10600. A.P. 6163, La Habana (Cuba); Godoy, W.; Maidana, N. L.; Vanin, V. R. [Laboratorio do Acelerador Linear, Instituto de Fisica - Universidade de Sao Paulo Rua do Matao, Travessa R, 187, 05508-900, SP (Brazil)

    2013-05-06

    A detailed characterization of a X-ray Si(Li) detector was performed to obtain the energy dependence of efficiency in the photon energy range of 6.4 - 59.5 keV, which was measured and reproduced by Monte Carlo (MC) simulations. Significant discrepancies between MC and experimental values were found when the manufacturer parameters of the detector were used in the simulation. A complete Computerized Tomography (CT) detector scan allowed to find the correct crystal dimensions and position inside the capsule. The computed efficiencies with the resulting detector model differed with the measured values no more than 10% in most of the energy range.

  13. Design and Testing of a Prototype Pixellated CZT Detector and Shield for Hard X-Ray Astronomy

    OpenAIRE

    Bloser, P. F.; Grindlay, J.E.; Narita, T; Jenkins, J. A.

    1999-01-01

    We report on the design and laboratory testing of a prototype imaging CZT detector intended for balloon flight testing in April 2000. The detector tests several key techniques needed for the construction of large-area CZT arrays, as required for proposed hard X-ray astronomy missions. Two 10 mm x 10 mm x 5 mm CZT detectors, each with a 4 x 4 array of 1.9 mm pixels on a 2.5 mm pitch, will be mounted in a ``flip-chip'' fashion on a printed circuit board carrier card; the detectors will be place...

  14. 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.

  15. High performance x-ray imaging detectors on foil using solutionprocessed organic photodiodes with extremely low dark leakage current (Presentation Recording)

    NARCIS (Netherlands)

    Kumar, A.; Moet, D.; Steen, J.L. van der; Breemen, A.J.J.M. van; Shanmugam, S.; Gilot, J.; Andriessen, H.A.J.M.; Matthias, S.; Ruetten, W.; Douglas, A.; Raaijmakers, R.; Malinowski, P.E.; Myny, K.; Gelinck, G.H.

    2011-01-01

    We demonstrate high performance X-ray imaging detectors on foil suitable for medical grade X-ray imaging applications. The detectors are based on solution-processed organic photodiodes forming bulk-heterojunctions from photovoltaic donor and acceptor blend. The organic photodiodes are deposited usin

  16. Development of Small-Pixel CZT Detectors for Future High-Resolution Hard X-ray Missions

    Science.gov (United States)

    Beilicke, Matthias

    Owing to recent breakthroughs in grazing incidence mirror technology, next-generation hard X-ray telescopes will achieve angular resolutions of between 5 and 10 arc seconds - about an order of magnitude better than that of the NuSTAR hard X-ray telescope. As a consequence, the next generation of hard X-ray telescopes will require pixelated hard X- ray detectors with pixels on a grid with a lattice constant of between 120 and 240 um. Additional detector requirements include a low energy threshold of less than 5 keV and an energy resolution of less than 1 keV. The science drivers for a high angular-resolution hard X-ray mission include studies and measurements of black hole spins, the cosmic evolution of super-massive black holes, AGN feedback, and the behavior of matter at very high densities. We propose a R&D research program to develop, optimize and study the performance of 100-200 um pixel pitch CdTe and Cadmium Zinc Telluride (CZT) detectors of 1-2 mm thickness. Our program aims at a comparison of the performance achieved with CdTe and CZT detectors, and the optimization of the pixel, steering grid, and guard ring anode patterns. Although these studies will use existing ASICs (Application Specific Integrated Circuits), our program also includes modest funds for the development of an ultra-low noise ASIC with a 2-D grid of readout pads that can be directly bonded to the 100-200 um pixel pitch CdTe and CZT detectors. The team includes the Washington University group (Prof. M. Beilicke and Co-I Prof. H.S.W. Krawczynski et al.), and co-investigator G. De Geronimo at Brookhaven National Laboratory (BNL). The Washington University group has a 10 year track record of innovative CZT detector R&D sponsored by the NASA Astronomy and Physics Research and Analysis (APRA) program. The accomplishments to date include the development of CZT detectors with pixel pitches between 350 um and 2.5 mm for the ProtoExist, EXIST, and X-Calibur hard X-ray missions with some of the best

  17. SDD探测器在X荧光分析系统中的应用%Application of SDD detector in the X-ray fluorescence analysis system

    Institute of Scientific and Technical Information of China (English)

    何伟龙; 王健; 杨勇

    2012-01-01

      介绍了硅漂移(SDD)探测器在X荧光分析系统中的应用,与SI-PIN探测器在能量分辨率、计数率等性能指标上的对比,以及在系统检出限上的实验对比,SDD探测器在性能指标及检出限上有着较大的优势。%  In this paper, the application of silicon drift detector (SDD) in the X-ray fluorescence (XRF) analysis system was mostly discussed. Compared with SI-PIN detector at the key performance parameter like energy resolution and count rates, and also on the detection limit, the SDD detector had a larger advantage.

  18. A High Spectral Resolution Observation of the Soft X-ray Diffuse Background with Thermal Detectors

    CERN Document Server

    McCammon, D; Apodaca, E; Tiest, W B; Cui, W; Deiker, S W; Galeazzi, M; Juda, M; Lesser, A; Mihara, T; Morgenthaler, J P; Sanders, W T; Zhang, J; Figueroa-Feliciano, E; Kelley, R L; Moseley, S H; Mushotzky, R F; Porter, F S; Stahle, C K; Szymkowiak, A E

    2002-01-01

    A high spectral resolution observation of the diffuse X-ray background in the 60 - 1000 eV energy range has been made using an array of thirty-six 1 mm^2 micro-calorimeters flown on a sounding rocket. Detector energy resolution ranged from 5-12 eV FWHM, and a composite spectrum of ~ 1 steradian of the background centered at l = 90, b = +60 was obtained with a net resolution of ~ 9 eV. The target area includes bright 1/4 keV regions, but avoids Loop I and the North Polar Spur. Lines of C VI, O VII, and O VIII are clearly detected with intensities of 5.4 +/- 2.3, 4.8 +/- 0.8, and 1.6 +/- 0.4 photons cm^-2 s^-1 sr^-1, respectively. The oxygen lines alone account for a majority of the diffuse background observed in the ROSAT R4 band that is not due to resolved extragalactic discrete sources. We also have a positive detection of the Fe-M line complex near 70 eV at an intensity consistent with previous upper limits that indicate substantial gas phase depletion of iron. We include a detailed description of the instr...

  19. Time and Energy Measurement Electronics for Silicon Drift Detector Aimed for X-ray Pulsar Navigation

    CERN Document Server

    Chen, Er-Lei; Ye, Chun-Feng; Liu, Shu-Bin; Jin, Dong-Dong; Lian, Jian; Hu, Hui-Jun

    2016-01-01

    A readout electronic with high time and energy resolution performance is designed for the SDD (Silicon Drift Detector) signals readout, which is aimed for X-ray pulsar based navigation (XNAV). For time measurement, the input signal is fed into a fast shaping and Constant Fraction Discrimination (CFD) circuit, and then be digitalized by a Time-to-Digital Converter (TDC) implemented in an Field Programmable Gate Array (FPGA), which is designed with a bin size of 2.5 ns. For energy measurement, a slow shaping and analog peak detection circuit is employed to acquire the energy information of input signals, which is then digitalized by a 14-bit Analog-to-Digital Converter (ADC). Both the time and energy measurement results are buffered and packaged in FPGA and then transmitted to Data Processing (DP) system. Test results indicate that the time resolution is about 3 ns, while the FWHM (Full Width at Half Maximum) of energy spectrum is better than 160 eV @ 5.9 keV, with the energy dynamic range from 1 keV to 10 keV....

  20. Multipixel characterization of imaging CZT detectors for hard x-ray imaging and spectroscopy

    Science.gov (United States)

    Vadawale, Santosh V.; Hong, Jae Sub; Grindlay, Jonathan E.; Williams, Peter; Zhang, Minhua; Bellm, Eric C.; Narita, Tomohiko; Craig, William W.; Parker, Bradford H.; Stahle, Carl M.; Yan, Feng

    2004-10-01

    We report our in-depth study of Cd-Zn-Te (CZT) crystals to determine an optimum pixel and guard band configuration for Hard X-ray imaging and spectroscopy. We tested 20x20x5mm crystals with 8x8 pixels on a 2.46mm pitch. We have studied different types of cathode / anode contacts and different pixel pad sizes. We present the measurements of leakage current as well as spectral response for each pixel. Our I-V measurement setup is custom designed to allow automated measurements of the I-V curves sequentially for all 64 pixels, whereas the radiation properties measurement setup allows for interchangeable crystals with the same XAIM3.2 ASIC readout from IDEAS. We have tested multiple crystals of each type, and each crystal in different positions to measure the variation between individual crystals and variation among the ASIC channels. We also compare the same crystals with and without a grounded guard band deposited on the crystal side walls vs. a floating guard band and compare results to simulations. This study was carried out to find the optimum CZT crystal configuration for prototype detectors for the proposed Black-Hole Finder mission, EXIST.

  1. Economical and Efficient Detector for Fluorescent X-Ray Absorption Spectroscopy

    Science.gov (United States)

    Khalid, S. M.; Rosenbaum, G.; Chance, B.

    1986-08-01

    The available synchrotron radiation sources and those proposed for construction in the near future in the US and abroad can produce fluxes of x-radiation high enough that the fluorescent and scattered flux even from biological samples approach and will exceed acceptable levels of counting losses even in fast photon counting detector system. Ionization chambers in current integration mode can afford very high flux and large apertures. But they suffer time limitations in the fraction of the millisecond region, microphonics, and the necessity of a gas supply of very constant pressure. We have developed an alternative detector system consisting of a photomultiplier tube equipped with a highly efficient ZnS (Ag) scintillator in current integration mode. It can have apertures up to 5 inches in diameter and a time resolution adequate for rapid reaction studies using synchrontron radiation (70 ns decay time to 10%). In initial tests, we did not detect any saturation effects with the fluxes available. The advantages of these detectors seem to be simplicity and reliability in addition to freedom from envi