DOE Office of Scientific and Technical Information (OSTI.GOV)

Vedantham, Srinivasan; Shrestha, Suman; Karellas, Andrew, E-mail: andrew.karellas@umassmed.edu

Purpose: High-resolution, photon-counting, energy-resolved detector with fast-framing capability can facilitate simultaneous acquisition of precontrast and postcontrast images for subtraction angiography without pixel registration artifacts and can facilitate high-resolution real-time imaging during image-guided interventions. Hence, this study was conducted to determine the spatial resolution characteristics of a hexagonal pixel array photon-counting cadmium telluride (CdTe) detector. Methods: A 650 μm thick CdTe Schottky photon-counting detector capable of concurrently acquiring up to two energy-windowed images was operated in a single energy-window mode to include photons of 10 keV or higher. The detector had hexagonal pixels with apothem of 30 μm resulting in pixelmore » pitch of 60 and 51.96 μm along the two orthogonal directions. The detector was characterized at IEC-RQA5 spectral conditions. Linear response of the detector was determined over the air kerma rate relevant to image-guided interventional procedures ranging from 1.3 nGy/frame to 91.4 μGy/frame. Presampled modulation transfer was determined using a tungsten edge test device. The edge-spread function and the finely sampled line spread function accounted for hexagonal sampling, from which the presampled modulation transfer function (MTF) was determined. Since detectors with hexagonal pixels require resampling to square pixels for distortion-free display, the optimal square pixel size was determined by minimizing the root-mean-squared-error of the aperture functions for the square and hexagonal pixels up to the Nyquist limit. Results: At Nyquist frequencies of 8.33 and 9.62 cycles/mm along the apothem and orthogonal to the apothem directions, the modulation factors were 0.397 and 0.228, respectively. For the corresponding axis, the limiting resolution defined as 10% MTF occurred at 13.3 and 12 cycles/mm, respectively. Evaluation of the aperture functions yielded an optimal square pixel size of 54 μm. After resampling to 54 μm square pixels using trilinear interpolation, the presampled MTF at Nyquist frequency of 9.26 cycles/mm was 0.29 and 0.24 along the orthogonal directions and the limiting resolution (10% MTF) occurred at approximately 12 cycles/mm. Visual analysis of a bar pattern image showed the ability to resolve close to 12 line-pairs/mm and qualitative evaluation of a neurovascular nitinol-stent showed the ability to visualize its struts at clinically relevant conditions. Conclusions: Hexagonal pixel array photon-counting CdTe detector provides high spatial resolution in single-photon counting mode. After resampling to optimal square pixel size for distortion-free display, the spatial resolution is preserved. The dual-energy capabilities of the detector could allow for artifact-free subtraction angiography and basis material decomposition. The proposed high-resolution photon-counting detector with energy-resolving capability can be of importance for several image-guided interventional procedures as well as for pediatric applications.« less

Achieving subpixel resolution with time-correlated transient signals in pixelated CdZnTe gamma-ray sensors using a focused laser beam (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ocampo Giraldo, Luis A.; Bolotnikov, Aleksey E.; Camarda, Giuseppe S.; Cui, Yonggang; De Geronimo, Gianluigi; Gul, Rubi; Fried, Jack; Hossain, Anwar; Unlu, Kenan; Vernon, Emerson; Yang, Ge; James, Ralph B.

2017-05-01

High-resolution position-sensitive detectors have been proposed to correct response non-uniformities in Cadmium Zinc Telluride (CZT) crystals by virtually subdividing the detectors area into small voxels and equalizing responses from each voxel. 3D pixelated detectors coupled with multichannel readout electronics are the most advanced type of CZT devices offering many options in signal processing and enhancing detector performance. One recent innovation proposed for pixelated detectors is to use the induced (transient) signals from neighboring pixels to achieve high sub-pixel position resolution while keeping large pixel sizes. The main hurdle in achieving this goal is the relatively low signal induced on the neighboring pixels because of the electrostatic shielding effect caused by the collecting pixel. In addition, to achieve high position sensitivity one should rely on time-correlated transient signals, which means that digitized output signals must be used. We present the results of our studies to measure the amplitude of the pixel signals so that these can be used to measure positions of the interaction points. This is done with the processing of digitized correlated time signals measured from several adjacent pixels taking into account rise-time and charge-sharing effects. In these measurements we used a focused pulsed laser to generate a 10-micron beam at one milliwatt (650-nm wavelength) over the detector surface while the collecting pixel was moved in cardinal directions. The results include measurements that present the benefits of combining conventional pixel geometry with digital pulse processing for the best approach in achieving sub-pixel position resolution with the pixel dimensions of approximately 2 mm. We also present the sub-pixel resolution measurements at comparable energies from various gamma emitting isotopes.

Nuclear resonant scattering measurements on (57)Fe by multichannel scaling with a 64-pixel silicon avalanche photodiode linear-array detector.

PubMed

Kishimoto, S; Mitsui, T; Haruki, R; Yoda, Y; Taniguchi, T; Shimazaki, S; Ikeno, M; Saito, M; Tanaka, M

2014-11-01

We developed a silicon avalanche photodiode (Si-APD) linear-array detector for use in nuclear resonant scattering experiments using synchrotron X-rays. The Si-APD linear array consists of 64 pixels (pixel size: 100 × 200 μm(2)) with a pixel pitch of 150 μm and depletion depth of 10 μm. An ultrafast frontend circuit allows the X-ray detector to obtain a high output rate of >10(7) cps per pixel. High-performance integrated circuits achieve multichannel scaling over 1024 continuous time bins with a 1 ns resolution for each pixel without dead time. The multichannel scaling method enabled us to record a time spectrum of the 14.4 keV nuclear radiation at each pixel with a time resolution of 1.4 ns (FWHM). This method was successfully applied to nuclear forward scattering and nuclear small-angle scattering on (57)Fe.

The Simbol-X Low Energy Detector

NASA Astrophysics Data System (ADS)

Lechner, Peter

2009-05-01

For the Low Energy Detector of Simbol-X a new type of active pixel sensor based on the integrated amplifier DEPFET has been developed. This concept combines large area, scalable pixel size, low noise, and ultra-fast readout. Flight representative prototypes have been processed with a performance matching the Simbol-X specifications and demonstrating the technology readiness.

Spectral Analysis of the Primary Flight Focal Plane Arrays for the Thermal Infrared Sensor

NASA Technical Reports Server (NTRS)

Montanaro, Matthew; Reuter, Dennis C.; Markham, Brian L.; Thome, Kurtis J.; Lunsford, Allen W.; Jhabvala, Murzy D.; Rohrbach, Scott O.; Gerace, Aaron D.

2011-01-01

Thermal Infrared Sensor (TIRS) is a (1) New longwave infrared (10 - 12 micron) sensor for the Landsat Data Continuity Mission, (2) 185 km ground swath; 100 meter pixel size on ground, (3) Pushbroom sensor configuration. Issue of Calibration are: (1) Single detector -- only one calibration, (2) Multiple detectors - unique calibration for each detector -- leads to pixel-to-pixel artifacts. Objectives are: (1) Predict extent of residual striping when viewing a uniform blackbody target through various atmospheres, (2) Determine how different spectral shapes affect the derived surface temperature in a realistic synthetic scene.

Simulations of radiation-damaged 3D detectors for the Super-LHC

NASA Astrophysics Data System (ADS)

Pennicard, D.; Pellegrini, G.; Fleta, C.; Bates, R.; O'Shea, V.; Parkes, C.; Tartoni, N.

2008-07-01

Future high-luminosity colliders, such as the Super-LHC at CERN, will require pixel detectors capable of withstanding extremely high radiation damage. In this article, the performances of various 3D detector structures are simulated with up to 1×1016 1 MeV- neq/cm2 radiation damage. The simulations show that 3D detectors have higher collection efficiency and lower depletion voltages than planar detectors due to their small electrode spacing. When designing a 3D detector with a large pixel size, such as an ATLAS sensor, different electrode column layouts are possible. Using a small number of n+ readout electrodes per pixel leads to higher depletion voltages and lower collection efficiency, due to the larger electrode spacing. Conversely, using more electrodes increases both the insensitive volume occupied by the electrode columns and the capacitive noise. Overall, the best performance after 1×1016 1 MeV- neq/cm2 damage is achieved by using 4-6 n+ electrodes per pixel.

The FE-I4 Pixel Readout Chip and the IBL Module

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbero, Marlon; Arutinov, David; Backhaus, Malte

2012-05-01

FE-I4 is the new ATLAS pixel readout chip for the upgraded ATLAS pixel detector. Designed in a CMOS 130 nm feature size process, the IC is able to withstand higher radiation levels compared to the present generation of ATLAS pixel Front-End FE-I3, and can also cope with higher hit rate. It is thus suitable for intermediate radii pixel detector layers in the High Luminosity LHC environment, but also for the inserted layer at 3.3 cm known as the 'Insertable B-Layer' project (IBL), at a shorter timescale. In this paper, an introduction to the FE-I4 will be given, focusing on testmore » results from the first full size FE-I4A prototype which has been available since fall 2010. The IBL project will be introduced, with particular emphasis on the FE-I4-based module concept.« less

Design Studies of a CZT-based Detector Combined with a Pixel-Geometry-Matching Collimator for SPECT Imaging.

PubMed

Weng, Fenghua; Bagchi, Srijeeta; Huang, Qiu; Seo, Youngho

2013-10-01

Single Photon Emission Computed Tomography (SPECT) suffers limited efficiency due to the need for collimators. Collimator properties largely decide the data statistics and image quality. Various materials and configurations of collimators have been investigated in many years. The main thrust of our study is to evaluate the design of pixel-geometry-matching collimators to investigate their potential performances using Geant4 Monte Carlo simulations. Here, a pixel-geometry-matching collimator is defined as a collimator which is divided into the same number of pixels as the detector's and the center of each pixel in the collimator is a one-to-one correspondence to that in the detector. The detector is made of Cadmium Zinc Telluride (CZT), which is one of the most promising materials for applications to detect hard X-rays and γ -rays due to its ability to obtain good energy resolution and high light output at room temperature. For our current project, we have designed a large-area, CZT-based gamma camera (20.192 cm×20.192 cm) with a small pixel pitch (1.60 mm). The detector is pixelated and hence the intrinsic resolution can be as small as the size of the pixel. Materials of collimator, collimator hole geometry, detection efficiency, and spatial resolution of the CZT detector combined with the pixel-matching collimator were calculated and analyzed under different conditions. From the simulation studies, we found that such a camera using rectangular holes has promising imaging characteristics in terms of spatial resolution, detection efficiency, and energy resolution.

Modulate chopper technique used in pyroelectric uncooled focal plane array thermal imager

NASA Astrophysics Data System (ADS)

He, Yuqing; Jin, Weiqi; Liu, Guangrong; Gao, Zhiyun; Wang, Xia; Wang, Lingxue

2002-09-01

Pyroelectric uncooled focal plane array (FPA) thermal imager has the advantages of low cost, small size, high responsibility and can work under room temperature, so it has great progress in recent years. As a matched technique, the modulate chopper has become one of the key techniques in uncooled FPA thermal imaging system. Now the Archimedes spiral cord chopper technique is mostly used. When it works, the chopper pushing scans the detector's pixel array, thus makes the pixels being exposed continuously. This paper simulates the shape of this kind of chopper, analyses the exposure time of the detector's every pixel, and also analyses the whole detector pixels' exposure sequence. From the analysis we can get the results: the parameter of Archimedes spiral cord, the detector's thermal time constant, the detector's geometrical dimension, the relative position of the detector to the chopper's spiral cord are the system's important parameters, they will affect the chopper's exposure efficiency and uniformity. We should design the chopper's relevant parameter according to the practical request to achieve the chopper's appropriate structure.

SNR improvement for hyperspectral application using frame and pixel binning

NASA Astrophysics Data System (ADS)

Rehman, Sami Ur; Kumar, Ankush; Banerjee, Arup

2016-05-01

Hyperspectral imaging spectrometer systems are increasingly being used in the field of remote sensing for variety of civilian and military applications. The ability of such instruments in discriminating finer spectral features along with improved spatial and radiometric performance have made such instruments a powerful tool in the field of remote sensing. Design and development of spaceborne hyper spectral imaging spectrometers poses lot of technological challenges in terms of optics, dispersion element, detectors, electronics and mechanical systems. The main factors that define the type of detectors are the spectral region, SNR, dynamic range, pixel size, number of pixels, frame rate, operating temperature etc. Detectors with higher quantum efficiency and higher well depth are the preferred choice for such applications. CCD based Si detectors serves the requirement of high well depth for VNIR band spectrometers but suffers from smear. Smear can be controlled by using CMOS detectors. Si CMOS detectors with large format arrays are available. These detectors generally have smaller pitch and low well depth. Binning technique can be used with available CMOS detectors to meet the large swath, higher resolution and high SNR requirements. Availability of larger dwell time of satellite can be used to bin multiple frames to increase the signal collection even with lesser well depth detectors and ultimately increase the SNR. Lab measurements reveal that SNR improvement by frame binning is more in comparison to pixel binning. Effect of pixel binning as compared to the frame binning will be discussed and degradation of SNR as compared to theoretical value for pixel binning will be analyzed.

Geometric correction methods for Timepix based large area detectors

NASA Astrophysics Data System (ADS)

Zemlicka, J.; Dudak, J.; Karch, J.; Krejci, F.

2017-01-01

X-ray micro radiography with the hybrid pixel detectors provides versatile tool for the object inspection in various fields of science. It has proven itself especially suitable for the samples with low intrinsic attenuation contrast (e.g. soft tissue in biology, plastics in material sciences, thin paint layers in cultural heritage, etc.). The limited size of single Medipix type detector (1.96 cm2) was recently overcome by the construction of large area detectors WidePIX assembled of Timepix chips equipped with edgeless silicon sensors. The largest already built device consists of 100 chips and provides fully sensitive area of 14.3 × 14.3 cm2 without any physical gaps between sensors. The pixel resolution of this device is 2560 × 2560 pixels (6.5 Mpix). The unique modular detector layout requires special processing of acquired data to avoid occurring image distortions. It is necessary to use several geometric compensations after standard corrections methods typical for this type of pixel detectors (i.e. flat-field, beam hardening correction). The proposed geometric compensations cover both concept features and particular detector assembly misalignment of individual chip rows of large area detectors based on Timepix assemblies. The former deals with larger border pixels in individual edgeless sensors and their behaviour while the latter grapple with shifts, tilts and steps between detector rows. The real position of all pixels is defined in Cartesian coordinate system and together with non-binary reliability mask it is used for the final image interpolation. The results of geometric corrections for test wire phantoms and paleo botanic material are presented in this article.

A CMOS-based high-resolution fluoroscope (HRF) detector prototype with 49.5μm pixels for use in endovascular image guided interventions (EIGI)

NASA Astrophysics Data System (ADS)

Russ, M.; Shankar, A.; Setlur Nagesh, S. V.; Ionita, C. N.; Bednarek, D. R.; Rudin, S.

2017-03-01

X-ray detectors to meet the high-resolution requirements for endovascular image-guided interventions (EIGIs) are being developed and evaluated. A new 49.5-micron pixel prototype detector is being investigated and compared to the current suite of high-resolution fluoroscopic (HRF) detectors. This detector featuring a 300-micron thick CsI(Tl) scintillator, and low electronic noise CMOS readout is designated the HRF- CMOS50. To compare the abilities of this detector with other existing high resolution detectors, a standard performance metric analysis was applied, including the determination of the modulation transfer function (MTF), noise power spectra (NPS), noise equivalent quanta (NEQ), and detective quantum efficiency (DQE) for a range of energies and exposure levels. The advantage of the smaller pixel size and reduced blurring due to the thin phosphor was exemplified when the MTF of the HRF-CMOS50 was compared to the other high resolution detectors, which utilize larger pixels, other optical designs or thicker scintillators. However, the thinner scintillator has the disadvantage of a lower quantum detective efficiency (QDE) for higher diagnostic x-ray energies. The performance of the detector as part of an imaging chain was examined by employing the generalized metrics GMTF, GNEQ, and GDQE, taking standard focal spot size and clinical imaging parameters into consideration. As expected, the disparaging effects of focal spot unsharpness, exacerbated by increasing magnification, degraded the higher-frequency performance of the HRF-CMOS50, while increasing scatter fraction diminished low-frequency performance. Nevertheless, the HRF-CMOS50 brings improved resolution capabilities for EIGIs, but would require increased sensitivity and dynamic range for future clinical application.

A new generation of small pixel pitch/SWaP cooled infrared detectors

NASA Astrophysics Data System (ADS)

Espuno, L.; Pacaud, O.; Reibel, Y.; Rubaldo, L.; Kerlain, A.; Péré-Laperne, N.; Dariel, A.; Roumegoux, J.; Brunner, A.; Kessler, A.; Gravrand, O.; Castelein, P.

2015-10-01

Following clear technological trends, the cooled IR detectors market is now in demand for smaller, more efficient and higher performance products. This demand pushes products developments towards constant innovations on detectors, read-out circuits, proximity electronics boards, and coolers. Sofradir was first to show a 10μm focal plane array (FPA) at DSS 2012, and announced the DAPHNIS 10μm product line back in 2014. This pixel pitch is a key enabler for infrared detectors with increased resolution. Sofradir recently achieved outstanding products demonstrations at this pixel pitch, which clearly demonstrate the benefits of adopting 10μm pixel pitch focal plane array-based detectors. Both HD and XGA Daphnis 10μm products also benefit from a global video datapath efficiency improvement by transitioning to digital video interfaces. Moreover, innovative smart pixels functionalities drastically increase product versatility. In addition to this strong push towards a higher pixels density, Sofradir acknowledges the need for smaller and lower power cooled infrared detector. Together with straightforward system interfaces and better overall performances, latest technological advances on SWAP-C (Size, Weight, Power and Cost) Sofradir products enable the advent of a new generation of high performance portable and agile systems (handheld thermal imagers, unmanned aerial vehicles, light gimbals etc...). This paper focuses on those features and performances that can make an actual difference in the field.

Modeling and evaluation of a high-resolution CMOS detector for cone-beam CT of the extremities.

PubMed

Cao, Qian; Sisniega, Alejandro; Brehler, Michael; Stayman, J Webster; Yorkston, John; Siewerdsen, Jeffrey H; Zbijewski, Wojciech

2018-01-01

Quantitative assessment of trabecular bone microarchitecture in extremity cone-beam CT (CBCT) would benefit from the high spatial resolution, low electronic noise, and fast scan time provided by complementary metal-oxide semiconductor (CMOS) x-ray detectors. We investigate the performance of CMOS sensors in extremity CBCT, in particular with respect to potential advantages of thin (<0.7 mm) scintillators offering higher spatial resolution. A cascaded systems model of a CMOS x-ray detector incorporating the effects of CsI:Tl scintillator thickness was developed. Simulation studies were performed using nominal extremity CBCT acquisition protocols (90 kVp, 0.126 mAs/projection). A range of scintillator thickness (0.35-0.75 mm), pixel size (0.05-0.4 mm), focal spot size (0.05-0.7 mm), magnification (1.1-2.1), and dose (15-40 mGy) was considered. The detectability index was evaluated for both CMOS and a-Si:H flat-panel detector (FPD) configurations for a range of imaging tasks emphasizing spatial frequencies associated with feature size aobj. Experimental validation was performed on a CBCT test bench in the geometry of a compact orthopedic CBCT system (SAD = 43.1 cm, SDD = 56.0 cm, matching that of the Carestream OnSight 3D system). The test-bench studies involved a 0.3 mm focal spot x-ray source and two CMOS detectors (Dalsa Xineos-3030HR, 0.099 mm pixel pitch) - one with the standard CsI:Tl thickness of 0.7 mm (C700) and one with a custom 0.4 mm thick scintillator (C400). Measurements of modulation transfer function (MTF), detective quantum efficiency (DQE), and CBCT scans of a cadaveric knee (15 mGy) were obtained for each detector. Optimal detectability for high-frequency tasks (feature size of ~0.06 mm, consistent with the size of trabeculae) was ~4× for the C700 CMOS detector compared to the a-Si:H FPD at nominal system geometry of extremity CBCT. This is due to ~5× lower electronic noise of a CMOS sensor, which enables input quantum-limited imaging at smaller pixel size. Optimal pixel size for high-frequency tasks was <0.1 mm for a CMOS, compared to ~0.14 mm for an a-Si:H FPD. For this fine pixel pitch, detectability of fine features could be improved by using a thinner scintillator to reduce light spread blur. A 22% increase in detectability of 0.06 mm features was found for the C400 configuration compared to C700. An improvement in the frequency at 50% modulation (f 50 ) of MTF was measured, increasing from 1.8 lp/mm for C700 to 2.5 lp/mm for C400. The C400 configuration also achieved equivalent or better DQE as C700 for frequencies above ~2 mm -1 . Images of cadaver specimens confirmed improved visualization of trabeculae with the C400 sensor. The small pixel size of CMOS detectors yields improved performance in high-resolution extremity CBCT compared to a-Si:H FPDs, particularly when coupled with a custom 0.4 mm thick scintillator. The results indicate that adoption of a CMOS detector in extremity CBCT can benefit applications in quantitative imaging of trabecular microstructure in humans. © 2017 American Association of Physicists in Medicine.

Development of a Timepix based detector for the NanoXCT project

NASA Astrophysics Data System (ADS)

Nachtrab, F.; Hofmann, T.; Speier, C.; Lučić, J.; Firsching, M.; Uhlmann, N.; Takman, P.; Heinzl, C.; Holmberg, A.; Krumm, M.; Sauerwein, C.

2015-11-01

The NanoXCT EU FP7 project [1] aims at developing a laboratory, i.e. bench top sized X-ray nano-CT system with a large field-of-view (FOV) for non-destructive testing needs in the micro- and nano-technology sector. The targeted voxel size is 50 nm at 0.175 mm FOV, the maximum FOV is 1 mm at 285 nm voxel size. Within the project a suitable X-ray source, detector and manipulation system have been developed. The system concept [2] omits the use of X-ray optics, to be able to provide a large FOV of up to 1 mm and to preserve the flexibility of state-of-the-art micro-CT systems. The targeted resolution will be reached via direct geometric magnification made possible by the development of a specialized high-flux nano-focus transmission X-ray tube. The end-user's demand for elemental analysis will be covered by energy-resolved measurement techniques, in particular a K-edge imaging method. Timepix [3] modules were chosen as the basis for the detector system, since a photon counting detector is advantageous for the long exposure times that come with very small focal spot sizes. Additional advantages are the small pixel size and adjustable energy threshold. To fulfill the requirements on field-of-view, a detector width 0> 300 pixels was needed. The NanoXCT detector consists of four Hexa modules with 500 μm silicon sensors supplied by X-ray Imaging Europe. An adapter board was developed to connect all four modules to one Fitpix3 readout. The final detector has an active area of 3072 × 512 pixels or approximately 17 × 3 cm2.In this contribution we present the development of the Timepix based NanoXCT detector, it's application in the NanoXCT project for CT and material specific measurements and the current status of results.

Improvement of spatial resolution in a Timepix based CdTe photon counting detector using ToT method

NASA Astrophysics Data System (ADS)

Park, Kyeongjin; Lee, Daehee; Lim, Kyung Taek; Kim, Giyoon; Chang, Hojong; Yi, Yun; Cho, Gyuseong

2018-05-01

Photon counting detectors (PCDs) have been recognized as potential candidates in X-ray radiography and computed tomography due to their many advantages over conventional energy-integrating detectors. In particular, a PCD-based X-ray system shows an improved contrast-to-noise ratio, reduced radiation exposure dose, and more importantly, exhibits a capability for material decomposition with energy binning. For some applications, a very high resolution is required, which translates into smaller pixel size. Unfortunately, small pixels may suffer from energy spectral distortions (distortion in energy resolution) due to charge sharing effects (CSEs). In this work, we propose a method for correcting CSEs by measuring the point of interaction of an incident X-ray photon by the time-of-threshold (ToT) method. Moreover, we also show that it is possible to obtain an X-ray image with a reduced pixel size by using the concept of virtual pixels at a given pixel size. To verify the proposed method, modulation transfer function (MTF) and signal-to-noise ratio (SNR) measurements were carried out with the Timepix chip combined with the CdTe pixel sensor. The X-ray test condition was set at 80 kVp with 5 μA, and a tungsten edge phantom and a lead line phantom were used for the measurements. Enhanced spatial resolution was achieved by applying the proposed method when compared to that of the conventional photon counting method. From experiment results, MTF increased from 6.3 (conventional counting method) to 8.3 lp/mm (proposed method) at 0.3 MTF. On the other hand, the SNR decreased from 33.08 to 26.85 dB due to four virtual pixels.

Section 1: Interfacial reactions and grain growth in ferroelectric SrBi{sub 2}Ta{sub 2}O (SBT) thin films on Si substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dickerson, B.D.; Zhang, X.; Desu, S.B.

1997-04-01

Much of the cost of traditional infrared cameras based on narrow-bandgap photoelectric semiconductors comes from the cryogenic cooling systems required to achieve high detectivity. Detectivity is inversely proportional to noise. Generation-recombination noise in photoelectric detectors increases roughly exponentially with temperature, but thermal noise in photoelectric detectors increases only linearly with temperature. Therefore `thermal detectors perform far better at room temperature than 8-14 {mu}m photon detectors.` Although potentially more affordable, uncooled pyroelectric cameras are less sensitive than cryogenic photoelectric cameras. One way to improve the sensitivity to cost ratio is to deposit ferroelectric pixels with good electrical properties directly on mass-produced,more » image-processing chips. `Good` properties include a strong temperature dependence of the remanent polarization, P{sub r}, or the relative dielectric constant, {epsilon}{sub r}, for sensitive operation in pyroelectric or dielectric mode, respectively, below or above the Curie temperature, which is 320 C for SBT. When incident infrared radiation is chopped, small oscillations in pixel temperature produce pyroelectric or dielectric alternating currents. The sensitivity of ferroelectric thermal detectors depends strongly on pixel microstructure, since P{sub r} and {epsilon}{sub r} increase with grain size during annealing. To manufacture SBT pixels on Si chips, acceptable SBT grain growth must be achieved at the lowest possible oxygen annealing temperature, to avoid damaging the Si chip below. Therefore current technical progress describes how grain size, reaction layer thickness, and electrical properties develop during the annealing of SBT pixels deposited on Si.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kishimoto, S., E-mail: syunji.kishimoto@kek.jp; Haruki, R.; Mitsui, T.

We developed a silicon avalanche photodiode (Si-APD) linear-array detector to be used for time-resolved X-ray scattering experiments using synchrotron X-rays. The Si-APD linear array consists of 64 pixels (pixel size: 100 × 200 μm{sup 2}) with a pixel pitch of 150 μm and a depletion depth of 10 μm. The multichannel scaler counted X-ray pulses over continuous 2046 time bins for every 0.5 ns and recorded a time spectrum at each pixel with a time resolution of 0.5 ns (FWHM) for 8.0 keV X-rays. Using the detector system, we were able to observe X-ray peaks clearly separated with 2 nsmore » interval in the multibunch-mode operation of the Photon Factory ring. The small-angle X-ray scattering for polyvinylidene fluoride film was also observed with the detector.« less

Development of a High Dynamic Range Pixel Array Detector for Synchrotrons and XFELs

NASA Astrophysics Data System (ADS)

Weiss, Joel Todd

Advances in synchrotron radiation light source technology have opened new lines of inquiry in material science, biology, and everything in between. However, x-ray detector capabilities must advance in concert with light source technology to fully realize experimental possibilities. X-ray free electron lasers (XFELs) place particularly large demands on the capabilities of detectors, and developments towards diffraction-limited storage ring sources also necessitate detectors capable of measuring very high flux [1-3]. The detector described herein builds on the Mixed Mode Pixel Array Detector (MM-PAD) framework, developed previously by our group to perform high dynamic range imaging, and the Adaptive Gain Integrating Pixel Detector (AGIPD) developed for the European XFEL by a collaboration between Deustsches Elektronen-Synchrotron (DESY), the Paul-Scherrer-Institute (PSI), the University of Hamburg, and the University of Bonn, led by Heinz Graafsma [4, 5]. The feasibility of combining adaptive gain with charge removal techniques to increase dynamic range in XFEL experiments is assessed by simulating XFEL scatter with a pulsed infrared laser. The strategy is incorporated into pixel prototypes which are evaluated with direct current injection to simulate very high incident x-ray flux. A fully functional 16x16 pixel hybrid integrating x-ray detector featuring several different pixel architectures based on the prototypes was developed. This dissertation describes its operation and characterization. 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 that achieved by counting pixel array detectors, but the integrators presented here are designed to tolerate a sustained flux >1011 x-rays/pixel/second. In addition, digitization of residual analog signals allows sensitivity for single x-rays or low flux signals. Pixel high flux linearity is evaluated by direct exposure to an unattenuated synchrotron source x-ray beam and flux measurements of more than 1010 9.52 keV x-rays/pixel/s are made. Detector sensitivity to small signals is evaluated and dominant sources of error are identified. These new pixels boast multiple orders of magnitude improvement in maximum sustained flux over the MM-PAD, which is capable of measuring a sustained flux in excess of 108 x-rays/pixel/second while maintaining sensitivity to smaller signals, down to single x-rays.

Spectral response characterization of CdTe sensors of different pixel size with the IBEX ASIC

NASA Astrophysics Data System (ADS)

Zambon, P.; Radicci, V.; Trueb, P.; Disch, C.; Rissi, M.; Sakhelashvili, T.; Schneebeli, M.; Broennimann, C.

2018-06-01

We characterized the spectral response of CdTe sensors with different pixel sizes - namely 75, 150 and 300 μm - bonded to the latest generation IBEX single photon counting ASIC developed at DECTRIS, to detect monochromatic X-ray energy in the range 10-60 keV. We present a comparison of pulse height spectra recorded for several energies, showing the dependence on the pixel size of the non-trivial atomic fluorescence and charge sharing effects that affect the detector response. The extracted energy resolution, in terms of full width at half maximum or FWHM, ranges from 1.5 to 4 keV according to the pixel size and chip configuration. We devoted a careful analysis to the Quantum Efficiency and to the Spectral Efficiency - a newly-introduced measure that quantifies the impact of fluorescence and escape phenomena on the spectrum integrity in high- Z material based detectors. We then investigated the influence of the photon flux on the aforementioned quantities up to 180 ṡ 106 cts/s/mm2 and 50 ṡ 106 cts/s/mm2 for the 150 μm and 300 μm pixel case, respectively. Finally, we complemented the experimental data with analytical and with Monte Carlo simulations - taking into account the stochastic nature of atomic fluorescence - with an excellent agreement.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weiss, Joel T.; Becker, Julian; Shanks, Katherine S.

There is a compelling need for a high frame rate imaging detector with a wide dynamic range, from single x-rays/pixel/pulse to >10{sup 6} x-rays/pixel/pulse, that is capable of operating at both x-ray free electron laser (XFEL) and 3rd generation sources with sustained fluxes of > 10{sup 11} x-rays/pixel/s [1, 2, 3]. We propose to meet these requirements with the High Dynamic Range Pixel Array Detector (HDR-PAD) by (a) increasing the speed of charge removal strategies [4], (b) increasing integrator range by implementing adaptive gain [5], and (c) exploiting the extended charge collection times of electron-hole pair plasma clouds that formmore » when a sufficiently large number of x-rays are absorbed in a detector sensor in a short period of time [6]. We have developed a measurement platform similar to the one used in [6] to study the effects of high electron-hole densities in silicon sensors using optical lasers to emulate the conditions found at XFELs. Characterizations of the employed tunable wavelength laser with picosecond pulse duration have shown Gaussian focal spots sizes of 6 ± 1 µm rms over the relevant spectrum and 2 to 3 orders of magnitude increase in available intensity compared to previous measurements presented in [6]. Results from measurements on a typical pixelated silicon diode intended for use with the HDR-PAD (150 µm pixel size, 500 µm thick sensor) are presented.« less

Subpixel mapping and test beam studies with a HV2FEI4v2 CMOS-Sensor-Hybrid Module for the ATLAS inner detector upgrade

NASA Astrophysics Data System (ADS)

Bisanz, T.; Große-Knetter, J.; Quadt, A.; Rieger, J.; Weingarten, J.

2017-08-01

The upgrade to the High Luminosity Large Hadron Collider will increase the instantaneous luminosity by more than a factor of 5, thus creating significant challenges to the tracking systems of all experiments. Recent advancement of active pixel detectors designed in CMOS processes provide attractive alternatives to the well-established hybrid design using passive sensors since they allow for smaller pixel sizes and cost effective production. This article presents studies of a high-voltage CMOS active pixel sensor designed for the ATLAS tracker upgrade. The sensor is glued to the read-out chip of the Insertable B-Layer, forming a capacitively coupled pixel detector. The pixel pitch of the device under test is 33× 125 μm2, while the pixels of the read-out chip have a pitch of 50× 250 μm2. Three pixels of the CMOS device are connected to one read-out pixel, the information of which of these subpixels is hit is encoded in the amplitude of the output signal (subpixel encoding). Test beam measurements are presented that demonstrate the usability of this subpixel encoding scheme.

High-sensitivity brain SPECT system using cadmium telluride (CdTe) semiconductor detector and 4-pixel matched collimator.

PubMed

Suzuki, Atsuro; Takeuchi, Wataru; Ishitsu, Takafumi; Tsuchiya, Katsutoshi; Morimoto, Yuichi; Ueno, Yuichiro; Kobashi, Keiji; Kubo, Naoki; Shiga, Tohru; Tamaki, Nagara

2013-11-07

For high-sensitivity brain imaging, we have developed a two-head single-photon emission computed tomography (SPECT) system using a CdTe semiconductor detector and 4-pixel matched collimator (4-PMC). The term, '4-PMC' indicates that the collimator hole size is matched to a 2 × 2 array of detector pixels. By contrast, a 1-pixel matched collimator (1-PMC) is defined as a collimator whose hole size is matched to one detector pixel. The performance of the higher-sensitivity 4-PMC was experimentally compared with that of the 1-PMC. The sensitivities of the 1-PMC and 4-PMC were 70 cps/MBq/head and 220 cps/MBq/head, respectively. The SPECT system using the 4-PMC provides superior image resolution in cold and hot rods phantom with the same activity and scan time to that of the 1-PMC. In addition, with half the usual scan time the 4-PMC provides comparable image quality to that of the 1-PMC. Furthermore, (99m)Tc-ECD brain perfusion images of healthy volunteers obtained using the 4-PMC demonstrated acceptable image quality for clinical diagnosis. In conclusion, our CdTe SPECT system equipped with the higher-sensitivity 4-PMC can provide better spatial resolution than the 1-PMC either in half the imaging time with the same administered activity, or alternatively, in the same imaging time with half the activity.

Optimal configuration of a low-dose breast-specific gamma camera based on semiconductor CdZnTe pixelated detectors

NASA Astrophysics Data System (ADS)

Genocchi, B.; Pickford Scienti, O.; Darambara, DG

2017-05-01

Breast cancer is one of the most frequent tumours in women. During the ‘90s, the introduction of screening programmes allowed the detection of cancer before the palpable stage, reducing its mortality up to 50%. About 50% of the women aged between 30 and 50 years present dense breast parenchyma. This percentage decreases to 30% for women between 50 to 80 years. In these women, mammography has a sensitivity of around 30%, and small tumours are covered by the dense parenchyma and missed in the mammogram. Interestingly, breast-specific gamma-cameras based on semiconductor CdZnTe detectors have shown to be of great interest to early diagnosis. Infact, due to the high energy, spatial resolution, and high sensitivity of CdZnTe, molecular breast imaging has been shown to have a sensitivity of about 90% independently of the breast parenchyma. The aim of this work is to determine the optimal combination of the detector pixel size, hole shape, and collimator material in a low dose dual head breast specific gamma camera based on a CdZnTe pixelated detector at 140 keV, in order to achieve high count rate, and the best possible image spatial resolution. The optimal combination has been studied by modeling the system using the Monte Carlo code GATE. Six different pixel sizes from 0.85 mm to 1.6 mm, two hole shapes, hexagonal and square, and two different collimator materials, lead and tungsten were considered. It was demonstrated that the camera achieved higher count rates, and better signal-to-noise ratio when equipped with square hole, and large pixels (> 1.3 mm). In these configurations, the spatial resolution was worse than using small pixel sizes (< 1.3 mm), but remained under 3.6 mm in all cases.

Photon small-field measurements with a CMOS active pixel sensor.

PubMed

Spang, F Jiménez; Rosenberg, I; Hedin, E; Royle, G

2015-06-07

In this work the dosimetric performance of CMOS active pixel sensors for the measurement of small photon beams is presented. The detector used consisted of an array of 520  × 520 pixels on a 25 µm pitch. Dosimetric parameters measured with this sensor were compared with data collected with an ionization chamber, a film detector and GEANT4 Monte Carlo simulations. The sensor performance for beam profiles measurements was evaluated for field sizes of 0.5  × 0.5 cm(2). The high spatial resolution achieved with this sensor allowed the accurate measurement of profiles, beam penumbrae and field size under lateral electronic disequilibrium. Field size and penumbrae agreed within 5.4% and 2.2% respectively with film measurements. Agreements with ionization chambers better than 1.0% were obtained when measuring tissue-phantom ratios. Output factor measurements were in good agreement with ionization chamber and Monte Carlo simulation. The data obtained from this imaging sensor can be easily analyzed to extract dosimetric information. The results presented in this work are promising for the development and implementation of CMOS active pixel sensors for dosimetry applications.

Improved image quality using monolithic scintillator detectors with dual-sided readout in a whole-body TOF-PET ring: a simulation study.

PubMed

Tabacchini, Valerio; Surti, Suleman; Borghi, Giacomo; Karp, Joel S; Schaart, Dennis R

2017-02-13

We have recently built and characterized the performance of a monolithic scintillator detector based on a 32 mm  ×  32 mm  ×  22 mm LYSO:Ce crystal read out by digital silicon photomultiplier (dSiPM) arrays coupled to the crystal front and back surfaces in a dual-sided readout (DSR) configuration. The detector spatial resolution appeared to be markedly better than that of a detector consisting of the same crystal with conventional back-sided readout (BSR). Here, we aim to evaluate the influence of this difference in the detector spatial response on the quality of reconstructed images, so as to quantify the potential benefit of the DSR approach for high-resolution, whole-body time-of-flight (TOF) positron emission tomography (PET) applications. We perform Monte Carlo simulations of clinical PET systems based on BSR and DSR detectors, using the results of our detector characterization experiments to model the detector spatial responses. We subsequently quantify the improvement in image quality obtained with DSR compared to BSR, using clinically relevant metrics such as the contrast recovery coefficient (CRC) and the area under the localized receiver operating characteristic curve (ALROC). Finally, we compare the results with simulated rings of pixelated detectors with DOI capability. Our results show that the DSR detector produces significantly higher CRC and increased ALROC values than the BSR detector. The comparison with pixelated systems indicates that one would need to choose a crystal size of 3.2 mm with three DOI layers to match the performance of the BSR detector, while a pixel size of 1.3 mm with three DOI layers would be required to get on par with the DSR detector.

Improved image quality using monolithic scintillator detectors with dual-sided readout in a whole-body TOF-PET ring: a simulation study

NASA Astrophysics Data System (ADS)

Tabacchini, Valerio; Surti, Suleman; Borghi, Giacomo; Karp, Joel S.; Schaart, Dennis R.

2017-03-01

We have recently built and characterized the performance of a monolithic scintillator detector based on a 32 mm  ×  32 mm  ×  22 mm LYSO:Ce crystal read out by digital silicon photomultiplier (dSiPM) arrays coupled to the crystal front and back surfaces in a dual-sided readout (DSR) configuration. The detector spatial resolution appeared to be markedly better than that of a detector consisting of the same crystal with conventional back-sided readout (BSR). Here, we aim to evaluate the influence of this difference in the detector spatial response on the quality of reconstructed images, so as to quantify the potential benefit of the DSR approach for high-resolution, whole-body time-of-flight (TOF) positron emission tomography (PET) applications. We perform Monte Carlo simulations of clinical PET systems based on BSR and DSR detectors, using the results of our detector characterization experiments to model the detector spatial responses. We subsequently quantify the improvement in image quality obtained with DSR compared to BSR, using clinically relevant metrics such as the contrast recovery coefficient (CRC) and the area under the localized receiver operating characteristic curve (ALROC). Finally, we compare the results with simulated rings of pixelated detectors with DOI capability. Our results show that the DSR detector produces significantly higher CRC and increased ALROC values than the BSR detector. The comparison with pixelated systems indicates that one would need to choose a crystal size of 3.2 mm with three DOI layers to match the performance of the BSR detector, while a pixel size of 1.3 mm with three DOI layers would be required to get on par with the DSR detector.

Position sensitive detection of neutrons in high radiation background field.

PubMed

Vavrik, D; Jakubek, J; Pospisil, S; Vacik, J

2014-01-01

We present the development of a high-resolution position sensitive device for detection of slow neutrons in the environment of extremely high γ and e(-) radiation background. We make use of a planar silicon pixelated (pixel size: 55 × 55 μm(2)) spectroscopic Timepix detector adapted for neutron detection utilizing very thin (10)B converter placed onto detector surface. We demonstrate that electromagnetic radiation background can be discriminated from the neutron signal utilizing the fact that each particle type produces characteristic ionization tracks in the pixelated detector. Particular tracks can be distinguished by their 2D shape (in the detector plane) and spectroscopic response using single event analysis. A Cd sheet served as thermal neutron stopper as well as intensive source of gamma rays and energetic electrons. Highly efficient discrimination was successful even at very low neutron to electromagnetic background ratio about 10(-4).

Position sensitive detection of neutrons in high radiation background field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vavrik, D., E-mail: vavrik@itam.cas.cz; Institute of Theoretical and Applied Mechanics, Academy of Sciences of the Czech Republic, Prosecka 76, 190 00 Prague 9; Jakubek, J.

We present the development of a high-resolution position sensitive device for detection of slow neutrons in the environment of extremely high γ and e{sup −} radiation background. We make use of a planar silicon pixelated (pixel size: 55 × 55 μm{sup 2}) spectroscopic Timepix detector adapted for neutron detection utilizing very thin {sup 10}B converter placed onto detector surface. We demonstrate that electromagnetic radiation background can be discriminated from the neutron signal utilizing the fact that each particle type produces characteristic ionization tracks in the pixelated detector. Particular tracks can be distinguished by their 2D shape (in the detector plane)more » and spectroscopic response using single event analysis. A Cd sheet served as thermal neutron stopper as well as intensive source of gamma rays and energetic electrons. Highly efficient discrimination was successful even at very low neutron to electromagnetic background ratio about 10{sup −4}.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kishimoto, S., E-mail: syunji.kishimoto@kek.jp; Haruki, R.; Mitsui, T.

We developed a silicon avalanche photodiode (Si-APD) linear-array detector for use in nuclear resonant scattering experiments using synchrotron X-rays. The Si-APD linear array consists of 64 pixels (pixel size: 100 × 200 μm{sup 2}) with a pixel pitch of 150 μm and depletion depth of 10 μm. An ultrafast frontend circuit allows the X-ray detector to obtain a high output rate of >10{sup 7} cps per pixel. High-performance integrated circuits achieve multichannel scaling over 1024 continuous time bins with a 1 ns resolution for each pixel without dead time. The multichannel scaling method enabled us to record a time spectrummore » of the 14.4 keV nuclear radiation at each pixel with a time resolution of 1.4 ns (FWHM). This method was successfully applied to nuclear forward scattering and nuclear small-angle scattering on {sup 57}Fe.« less

WE-G-204-05: Relative Object Detectability Evaluation of a New High Resolution A-Se Direct Detection System Compared to Indirect Micro-Angiographic Fluoroscopic (MAF) Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russ, M; Nagesh, S Setlur; Ionita, C

2015-06-15

Purpose: To evaluate the task specific imaging performance of a new 25µm pixel pitch, 1000µm thick amorphous selenium direct detection system with CMOS readout for typical angiographic exposure parameters using the relative object detectability (ROD) metric. Methods: The ROD metric uses a simulated object function weighted at each spatial frequency by the detectors’ detective quantum efficiency (DQE), which is an intrinsic performance metric. For this study, the simulated objects were aluminum spheres of varying diameter (0.05–0.6mm). The weighted object function is then integrated over the full range of detectable frequencies inherent to each detector, and a ratio is taken ofmore » the resulting value for two detectors. The DQE for the 25µm detector was obtained from a simulation of a proposed a-Se detector using an exposure of 200µR for a 50keV x-ray beam. This a-Se detector was compared to two microangiographic fluoroscope (MAF) detectors [the MAF-CCD with pixel size of 35µm and Nyquist frequency of 14.2 cycles/mm and the MAF-CMOS with pixel size of 75µm and Nyquist frequency of 6.6 cycles/mm] and a standard flat-panel detector (FPD with pixel size of 194µm and Nyquist frequency of 2.5cycles/mm). Results: ROD calculations indicated vastly superior performance by the a-Se detector in imaging small aluminum spheres. For the 50µm diameter sphere, the ROD values for the a-Se detector compared to the MAF-CCD, the MAF-CMOS, and the FPD were 7.3, 9.3 and 58, respectively. Detector performance in the low frequency regime was dictated by each detector’s DQE(0) value. Conclusion: The a-Se with CMOS readout is unique and appears to have distinctive advantages of incomparable high resolution, low noise, no readout lag, and expandable design. The a-Se direct detection system will be a powerful imaging tool in angiography, with potential break-through applications in diagnosis and treatment of neuro-vascular disease. Supported by NIH Grant: 2R01EB002873 and an equipment grant from Toshiba Medical Systems Corporation.« less

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

PubMed

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

2009-06-11

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

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

PubMed

Stierstorfer, Karl

2018-01-01

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Lan; Hill, K. W.; Bitter, M.

Here, a high spatial resolution of a few μm is often required for probing small-scale high-energy-density plasmas using high resolution x-ray imaging spectroscopy. This resolution can be achieved by adjusting system magnification to overcome the inherent limitation of the detector pixel size. Laboratory experiments on investigating the relation between spatial resolution and system magnification for a spherical crystal spectrometer are presented. Tungsten Lβ 2 rays from a tungsten-target micro-focus x-ray tube were diffracted by a Ge 440 crystal, which was spherically bent to a radius of 223 mm, and imaged onto an x-ray CCD with 13-μm pixel size. The source-to-crystalmore » (p) and crystal-to-detector (q) distances were varied to produce spatial magnifications ( M = q/p) ranging from 2 to 10. The inferred instrumental spatial width reduces with increasing system magnification M. However, the experimental measurement at each M is larger than the theoretical value of pixel size divided by M. Future work will focus on investigating possible broadening mechanisms that limit the spatial resolution.« less

Signal-Conditioning Block of a 1 × 200 CMOS Detector Array for a Terahertz Real-Time Imaging System

PubMed Central

Yang, Jong-Ryul; Lee, Woo-Jae; Han, Seong-Tae

2016-01-01

A signal conditioning block of a 1 × 200 Complementary Metal-Oxide-Semiconductor (CMOS) detector array is proposed to be employed with a real-time 0.2 THz imaging system for inspecting large areas. The plasmonic CMOS detector array whose pixel size including an integrated antenna is comparable to the wavelength of the THz wave for the imaging system, inevitably carries wide pixel-to-pixel variation. To make the variant outputs from the array uniform, the proposed signal conditioning block calibrates the responsivity of each pixel by controlling the gate bias of each detector and the voltage gain of the lock-in amplifiers in the block. The gate bias of each detector is modulated to 1 MHz to improve the signal-to-noise ratio of the imaging system via the electrical modulation by the conditioning block. In addition, direct current (DC) offsets of the detectors in the array are cancelled by initializing the output voltage level from the block. Real-time imaging using the proposed signal conditioning block is demonstrated by obtaining images at the rate of 19.2 frame-per-sec of an object moving on the conveyor belt with a scan width of 20 cm and a scan speed of 25 cm/s. PMID:26950128

Signal-Conditioning Block of a 1 × 200 CMOS Detector Array for a Terahertz Real-Time Imaging System.

PubMed

Yang, Jong-Ryul; Lee, Woo-Jae; Han, Seong-Tae

2016-03-02

A signal conditioning block of a 1 × 200 Complementary Metal-Oxide-Semiconductor (CMOS) detector array is proposed to be employed with a real-time 0.2 THz imaging system for inspecting large areas. The plasmonic CMOS detector array whose pixel size including an integrated antenna is comparable to the wavelength of the THz wave for the imaging system, inevitably carries wide pixel-to-pixel variation. To make the variant outputs from the array uniform, the proposed signal conditioning block calibrates the responsivity of each pixel by controlling the gate bias of each detector and the voltage gain of the lock-in amplifiers in the block. The gate bias of each detector is modulated to 1 MHz to improve the signal-to-noise ratio of the imaging system via the electrical modulation by the conditioning block. In addition, direct current (DC) offsets of the detectors in the array are cancelled by initializing the output voltage level from the block. Real-time imaging using the proposed signal conditioning block is demonstrated by obtaining images at the rate of 19.2 frame-per-sec of an object moving on the conveyor belt with a scan width of 20 cm and a scan speed of 25 cm/s.

Optimized light sharing for high-resolution TOF PET detector based on digital silicon photomultipliers.

PubMed

Marcinkowski, R; España, S; Van Holen, R; Vandenberghe, S

2014-12-07

The majority of current whole-body PET scanners are based on pixelated scintillator arrays with a transverse pixel size of 4 mm. However, recent studies have shown that decreasing the pixel size to 2 mm can significantly improve image spatial resolution. In this study, the performance of Digital Photon Counter (DPC) from Philips Digital Photon Counting (PDPC) was evaluated to determine their potential for high-resolution whole-body time of flight (TOF) PET scanners. Two detector configurations were evaluated. First, the DPC3200-44-22 DPC array was coupled to a LYSO block of 15 × 15 2 × 2 × 22 mm(3) pixels through a 1 mm thick light guide. Due to light sharing among the dies neighbour logic of the DPC was used. In a second setup the same DPC was coupled directly to a scalable 4 × 4 LYSO matrix of 1.9 × 1.9 × 22 mm(3) crystals with a dedicated reflector arrangement allowing for controlled light sharing patterns inside the matrix. With the first approach an average energy resolution of 14.5% and an average CRT of 376 ps were achieved. For the second configuration an average energy resolution of 11% and an average CRT of 295 ps were achieved. Our studies show that the DPC is a suitable photosensor for a high-resolution TOF-PET detector. The dedicated reflector arrangement allows one to achieve better performances than the light guide approach. The count loss, caused by dark counts, is overcome by fitting the matrix size to the size of DPC single die.

Recent X-ray hybrid CMOS detector developments and measurements

NASA Astrophysics Data System (ADS)

Hull, Samuel V.; Falcone, Abraham D.; Burrows, David N.; Wages, Mitchell; Chattopadhyay, Tanmoy; McQuaide, Maria; Bray, Evan; Kern, Matthew

2017-08-01

The Penn State X-ray detector lab, in collaboration with Teledyne Imaging Sensors (TIS), have progressed their efforts to improve soft X-ray Hybrid CMOS detector (HCD) technology on multiple fronts. Having newly acquired a Teledyne cryogenic SIDECARTM ASIC for use with HxRG devices, measurements were performed with an H2RG HCD and the cooled SIDECARTM. We report new energy resolution and read noise measurements, which show a significant improvement over room temperature SIDECARTM operation. Further, in order to meet the demands of future high-throughput and high spatial resolution X-ray observatories, detectors with fast readout and small pixel sizes are being developed. We report on characteristics of new X-ray HCDs with 12.5 micron pitch that include in-pixel CDS circuitry and crosstalk-eliminating CTIA amplifiers. In addition, PSU and TIS are developing a new large-scale array Speedster-EXD device. The original 64 × 64 pixel Speedster-EXD prototype used comparators in each pixel to enable event driven readout with order of magnitude higher effective readout rates, which will now be implemented in a 550 × 550 pixel device. Finally, the detector lab is involved in a sounding rocket mission that is slated to fly in 2018 with an off-plane reflection grating array and an H2RG X-ray HCD. We report on the planned detector configuration for this mission, which will increase the NASA technology readiness level of X-ray HCDs to TRL 9.

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

NASA Astrophysics Data System (ADS)

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 pixels. By using a modular assembly of the detector, the width can be chosen as multiples of 512 pixels. With a frame rate of up to 300 frames/s (full resolution) or 1200 frame/s (analog binning to 400 μ m pixel pitch) time-resolved 3D CT applications become possible. Two versions of the detector are in development, one with a high resolution scintillator and one with a thick, structured and very efficient scintillator (pitch 400 μ m). This way the detector can even work with X-ray energies up to 450 kVp.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Philipp, Hugh T., E-mail: htp2@cornell.edu; Tate, Mark W.; Purohit, Prafull

Modern storage rings are readily capable of providing intense x-ray pulses, tens of picoseconds in duration, millions of times per second. Exploiting the temporal structure of these x-ray sources opens avenues for studying rapid structural changes in materials. Many processes (e.g. crack propagation, deformation on impact, turbulence, etc.) differ in detail from one sample trial to the next and would benefit from the ability to record successive x-ray images with single x-ray sensitivity while framing at 5 to 10 MHz rates. To this end, we have pursued the development of fast x-ray imaging detectors capable of collecting bursts of imagesmore » that enable the isolation of single synchrotron bunches and/or bunch trains. The detector technology used is the hybrid pixel array detector (PAD) with a charge integrating front-end, and high-speed, in-pixel signal storage elements. A 384×256 pixel version, the Keck-PAD, with 150 µm × 150 µm pixels and 8 dedicated in-pixel storage elements is operational, has been tested at CHESS, and has collected data for compression wave studies. An updated version with 27 dedicated storage capacitors and identical pixel size has been fabricated.« less

Three-dimensional cascaded system analysis of a 50 µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis.

PubMed

Zhao, C; Vassiljev, N; Konstantinidis, A C; Speller, R D; Kanicki, J

2017-03-07

High-resolution, low-noise x-ray detectors based on the complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been developed and proposed for digital breast tomosynthesis (DBT). In this study, we evaluated the three-dimensional (3D) imaging performance of a 50 µm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). The two-dimensional (2D) angle-dependent modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were experimentally characterized and modeled using the cascaded system analysis at oblique incident angles up to 30°. The cascaded system model was extended to the 3D spatial frequency space in combination with the filtered back-projection (FBP) reconstruction method to calculate the 3D and in-plane MTF, NNPS and DQE parameters. The results demonstrate that the beam obliquity blurs the 2D MTF and DQE in the high spatial frequency range. However, this effect can be eliminated after FBP image reconstruction. In addition, impacts of the image acquisition geometry and detector parameters were evaluated using the 3D cascaded system analysis for DBT. The result shows that a wider projection angle range (e.g.  ±30°) improves the low spatial frequency (below 5 mm -1 ) performance of the CMOS APS detector. In addition, to maintain a high spatial resolution for DBT, a focal spot size of smaller than 0.3 mm should be used. Theoretical analysis suggests that a pixelated scintillator in combination with the 50 µm pixel pitch CMOS APS detector could further improve the 3D image resolution. Finally, the 3D imaging performance of the CMOS APS and an indirect amorphous silicon (a-Si:H) thin-film transistor (TFT) passive pixel sensor (PPS) detector was simulated and compared.

Three-dimensional cascaded system analysis of a 50 µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

NASA Astrophysics Data System (ADS)

Zhao, C.; Vassiljev, N.; Konstantinidis, A. C.; Speller, R. D.; Kanicki, J.

2017-03-01

High-resolution, low-noise x-ray detectors based on the complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been developed and proposed for digital breast tomosynthesis (DBT). In this study, we evaluated the three-dimensional (3D) imaging performance of a 50 µm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). The two-dimensional (2D) angle-dependent modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were experimentally characterized and modeled using the cascaded system analysis at oblique incident angles up to 30°. The cascaded system model was extended to the 3D spatial frequency space in combination with the filtered back-projection (FBP) reconstruction method to calculate the 3D and in-plane MTF, NNPS and DQE parameters. The results demonstrate that the beam obliquity blurs the 2D MTF and DQE in the high spatial frequency range. However, this effect can be eliminated after FBP image reconstruction. In addition, impacts of the image acquisition geometry and detector parameters were evaluated using the 3D cascaded system analysis for DBT. The result shows that a wider projection angle range (e.g.  ±30°) improves the low spatial frequency (below 5 mm-1) performance of the CMOS APS detector. In addition, to maintain a high spatial resolution for DBT, a focal spot size of smaller than 0.3 mm should be used. Theoretical analysis suggests that a pixelated scintillator in combination with the 50 µm pixel pitch CMOS APS detector could further improve the 3D image resolution. Finally, the 3D imaging performance of the CMOS APS and an indirect amorphous silicon (a-Si:H) thin-film transistor (TFT) passive pixel sensor (PPS) detector was simulated and compared.

18F-FDG positron autoradiography with a particle counting silicon pixel detector.

PubMed

Russo, P; Lauria, A; Mettivier, G; Montesi, M C; Marotta, M; Aloj, L; Lastoria, S

2008-11-07

We report on tests of a room-temperature particle counting silicon pixel detector of the Medipix2 series as the detector unit of a positron autoradiography (AR) system, for samples labelled with (18)F-FDG radiopharmaceutical used in PET studies. The silicon detector (1.98 cm(2) sensitive area, 300 microm thick) has high intrinsic resolution (55 microm pitch) and works by counting all hits in a pixel above a certain energy threshold. The present work extends the detector characterization with (18)F-FDG of a previous paper. We analysed the system's linearity, dynamic range, sensitivity, background count rate, noise, and its imaging performance on biological samples. Tests have been performed in the laboratory with (18)F-FDG drops (37-37 000 Bq initial activity) and ex vivo in a rat injected with 88.8 MBq of (18)F-FDG. Particles interacting in the detector volume produced a hit in a cluster of pixels whose mean size was 4.3 pixels/event at 11 keV threshold and 2.2 pixels/event at 37 keV threshold. Results show a sensitivity for beta(+) of 0.377 cps Bq(-1), a dynamic range of at least five orders of magnitude and a lower detection limit of 0.0015 Bq mm(-2). Real-time (18)F-FDG positron AR images have been obtained in 500-1000 s exposure time of thin (10-20 microm) slices of a rat brain and compared with 20 h film autoradiography of adjacent slices. The analysis of the image contrast and signal-to-noise ratio in a rat brain slice indicated that Poisson noise-limited imaging can be approached in short (e.g. 100 s) exposures, with approximately 100 Bq slice activity, and that the silicon pixel detector produced a higher image quality than film-based AR.

Influence of detector pixel size, TOF resolution and DOI on image quality in MR-compatible whole-body PET.

PubMed

Thoen, Hendrik; Keereman, Vincent; Mollet, Pieter; Van Holen, Roel; Vandenberghe, Stefaan

2013-09-21

The optimization of a whole-body PET system remains a challenging task, as the imaging performance is influenced by a complex interaction of different design parameters. However, it is not always clear which parameters have the largest impact on image quality and are most eligible for optimization. To determine this, we need to be able to assess their influence on image quality. We performed Monte-Carlo simulations of a whole-body PET scanner to predict the influence on image quality of three detector parameters: the TOF resolution, the transverse pixel size and depth-of-interaction (DOI)-correction. The inner diameter of the PET scanner was 65 cm, small enough to allow physical integration into a simultaneous PET-MR system. Point sources were used to evaluate the influence of transverse pixel size and DOI-correction on spatial resolution as function of radial distance. To evaluate the influence on contrast recovery and pixel noise a cylindrical phantom of 35 cm diameter was used, representing a large patient. The phantom contained multiple hot lesions with 5 mm diameter. These lesions were placed at radial distances of 50, 100 and 150 mm from the center of the field-of-view, to be able to study the effects at different radial positions. The non-prewhitening (NPW) observer was used for objective analysis of the detectability of the hot lesions in the cylindrical phantom. Based on this analysis the NPW-SNR was used to quantify the relative improvements in image quality due to changes of the variable detector parameters. The image quality of a whole-body PET scanner can be improved significantly by reducing the transverse pixel size from 4 to 2.6 mm and improving the TOF resolution from 600 to 400 ps and further from 400 to 200 ps. Compared to pixel size, the TOF resolution has the larger potential to increase image quality for the simulated phantom. The introduction of two layer DOI-correction only leads to a modest improvement for the spheres at radial distance of 150 mm from the center of the transaxial FOV.

Laboratory Measurement of the Brighter-fatter Effect in an H2RG Infrared Detector

NASA Astrophysics Data System (ADS)

Plazas, A. A.; Shapiro, C.; Smith, R.; Huff, E.; Rhodes, J.

2018-06-01

The “brighter-fatter” (BF) effect is a phenomenon—originally discovered in charge coupled devices—in which the size of the detector point-spread function (PSF) increases with brightness. We present, for the first time, laboratory measurements demonstrating the existence of the effect in a Hawaii-2RG HgCdTe near-infrared (NIR) detector. We use JPL’s Precision Projector Laboratory, a facility for emulating astronomical observations with UV/VIS/NIR detectors, to project about 17,000 point sources onto the detector to stimulate the effect. After calibrating the detector for nonlinearity with flat-fields, we find evidence that charge is nonlinearly shifted from bright pixels to neighboring pixels during exposures of point sources, consistent with the existence of a BF-type effect. NASAs Wide Field Infrared Survey Telescope (WFIRST) will use similar detectors to measure weak gravitational lensing from the shapes of hundreds of million of galaxies in the NIR. The WFIRST PSF size must be calibrated to ≈0.1% to avoid biased inferences of dark matter and dark energy parameters; therefore further study and calibration of the BF effect in realistic images will be crucial.

Pixel CdTe semiconductor module to implement a sub-MeV imaging detector for astrophysics

NASA Astrophysics Data System (ADS)

Gálvez, J.-L.; Hernanz, M.; Álvarez, L.; Artigues, B.; Álvarez, J.-M.; Ullán, M.; Pellegrini, G.; Lozano, M.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

2017-03-01

Stellar explosions are relevant and interesting astrophysical phenomena. Since long ago we have been working on the characterization of nova and supernova explosions in X and gamma rays, with the use of space missions such as INTEGRAL, XMM-Newton and Swift. We have been also involved in feasibility studies of future instruments in the energy range from several keV up to a few MeV, in collaboration with other research institutes, such as GRI, DUAL and e-ASTROGAM. High sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators, e.g., Supernovae, Classical Novae, Supernova Remnants (SNRs), Gamma-Ray Bursts (GRBs). In order to fulfil the combined requirement of high detection efficiency with good spatial and energy resolution, an initial module prototype based on CdTe pixel detectors is being developed. The detector dimensions are 12.5mm x 12.5mm x 2mm, with a pixel pitch of 1mm x 1mm. Each pixel is bump bonded to a fanout board made of Sapphire substrate and routed to the corresponding input channel of the readout ASIC, to measure pixel position and pulse height for each incident gamma-ray photon. An ohmic CdTe pixel detector has been characterised by means of 57Co, 133Ba and 22Na sources. Based on this, its spectroscopic performance and the influence of charge sharing is reported here. The pixel study is complemented by the simulation of the CdTe module performance using the GEANT 4 and MEGALIB tools, which will help us to optimise the pixel size selection.

The CAOS camera platform: ushering in a paradigm change in extreme dynamic range imager design

NASA Astrophysics Data System (ADS)

Riza, Nabeel A.

2017-02-01

Multi-pixel imaging devices such as CCD, CMOS and Focal Plane Array (FPA) photo-sensors dominate the imaging world. These Photo-Detector Array (PDA) devices certainly have their merits including increasingly high pixel counts and shrinking pixel sizes, nevertheless, they are also being hampered by limitations in instantaneous dynamic range, inter-pixel crosstalk, quantum full well capacity, signal-to-noise ratio, sensitivity, spectral flexibility, and in some cases, imager response time. Recently invented is the Coded Access Optical Sensor (CAOS) Camera platform that works in unison with current Photo-Detector Array (PDA) technology to counter fundamental limitations of PDA-based imagers while providing high enough imaging spatial resolution and pixel counts. Using for example the Texas Instruments (TI) Digital Micromirror Device (DMD) to engineer the CAOS camera platform, ushered in is a paradigm change in advanced imager design, particularly for extreme dynamic range applications.

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

PubMed

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.

Progress of MCT Detector Technology at AIM Towards Smaller Pitch and Lower Dark Current

NASA Astrophysics Data System (ADS)

Eich, D.; Schirmacher, W.; Hanna, S.; Mahlein, K. M.; Fries, P.; Figgemeier, H.

2017-09-01

We present our latest results on cooled p-on- n planar mercury cadmium telluride (MCT) photodiode technology. Along with a reduction in dark current for raising the operating temperature ( T op), AIM INFRAROT-MODULE GmbH (AIM) has devoted its development efforts to shrinking the pixel size. Both are essential requirements to meet the market demands for reduced size, weight and power and high-operating temperature applications. Detectors based on the p-on- n technology developed at AIM now span the spectrum from the mid-wavelength infrared (MWIR) to the very long wavelength infrared (VLWIR) with cut-off wavelengths from 5 μm to about 13.5 μm at 80 K. The development of the p-on- n technology for VLWIR as well as for MWIR is mainly implemented in a planar photodetector design with a 20- μm pixel pitch. For the VLWIR, dark currents significantly reduced as compared to `Tennant's Rule 07' are demonstrated for operating temperatures between 30 K and 100 K. This allows for the same dark current performance at a 20 K higher operating temperature than with previous AIM technology. For MWIR detectors with a 20- μm pitch, noise equivalent temperature differences of less than 30 mK are obtained up to 170 K. This technology has been transferred to our small pixel pitch high resolution (XGA) MWIR detector with 1024 × 768 pixels at a 10- μm pitch. Excellent performance at an operating temperature of 160 K is demonstrated.

KENIS: a high-performance thermal imager developed using the OSPREY IR detector

NASA Astrophysics Data System (ADS)

Goss, Tristan M.; Baker, Ian M.

2000-07-01

`KENIS', a complete, high performance, compact and lightweight thermal imager, is built around the `OSPREY' infrared detector from BAE systems Infrared Ltd. The `OSPREY' detector uses a 384 X 288 element CMT array with a 20 micrometers pixel size and cooled to 120 K. The relatively small pixel size results in very compact cryogenics and optics, and the relatively high operating temperature provides fast start-up time, low power consumption and long operating life. Requiring single input supply voltage and consuming less than 30 watts of power, the thermal imager generates both analogue and digital format outputs. The `KENIS' lens assembly features a near diffraction limited dual field-of-view optical system that has been designed to be athermalized and switches between fields in less than one second. The `OSPREY' detector produces near background limited performance with few defects and has special, pixel level circuitry to eliminate crosstalk and blooming effects. This, together with signal processing based on an effective two-point fixed pattern noise correction algorithm, results in high quality imagery and a thermal imager that is suitable for most traditional thermal imaging applications. This paper describes the rationale used in the development of the `KENIS' thermal imager, and highlights the potential performance benefits to the user's system, primarily gained by selecting the `OSPREY' infra-red detector within the core of the thermal imager.

Nature's crucible: Manufacturing optical nonlinearities for high resolution, high sensitivity encoding in the compound eye of the fly, Musca domestica

NASA Technical Reports Server (NTRS)

Wilcox, Mike

1993-01-01

The number of pixels per unit area sampling an image determines Nyquist resolution. Therefore, the highest pixel density is the goal. Unfortunately, as reduction in pixel size approaches the wavelength of light, sensitivity is lost and noise increases. Animals face the same problems and have achieved novel solutions. Emulating these solutions offers potentially unlimited sensitivity with detector size approaching the diffraction limit. Once an image is 'captured', cellular preprocessing of information allows extraction of high resolution information from the scene. Computer simulation of this system promises hyperacuity for machine vision.

First full dynamic range calibration of the JUNGFRAU photon detector

NASA Astrophysics Data System (ADS)

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

2018-01-01

The JUNGFRAU detector is a charge integrating hybrid silicon pixel detector developed at the Paul Scherrer Institut for photon science applications, in particular for the upcoming free electron laser SwissFEL. With a high dynamic range, analogue readout, low noise and three automatically switching gains, JUNGFRAU promises excellent performance not only at XFELs but also at synchrotrons in areas such as protein crystallography, ptychography, pump-probe and time resolved measurements. To achieve its full potential, the detector must be calibrated on a pixel-by-pixel basis. This contribution presents the current status of the JUNGFRAU calibration project, in which a variety of input charge sources are used to parametrise the energy response of the detector across four orders of magnitude of dynamic range. Building on preliminary studies, the first full calibration procedure of a JUNGFRAU 0.5 Mpixel module is described. The calibration is validated using alternative sources of charge deposition, including laboratory experiments and measurements at ESRF and LCLS. The findings from these measurements are presented. Calibrated modules have already been used in proof-of-principle style protein crystallography experiments at the SLS. A first look at selected results is shown. Aspects such as the conversion of charge to number of photons, treatment of multi-size pixels and the origin of non-linear response are also discussed.

Influence of magnetic fields on charge sharing caused by diffusion in medipix detectors with a Si sensor

NASA Astrophysics Data System (ADS)

Jamil, Ako; Filipenko, Mykhaylo; Gleixner, Thomas; Anton, Gisela; Michel, Thilo

2016-02-01

The spatial and energy resolution of hybrid photon counting pixel detectors like the Timepix detector can suffer from charge sharing. Due to diffusion an initially point-like charge carrier distribution generated by ionizing radiation becomes a typically Gaussian-like distribution when arriving at the pixel electrodes. This leads to loss of charge information in edge pixels if the amount of charge in the pixel fall below the discriminator threshold. In this work we investigated the reduction of charge sharing by applying a magnetic field parallel to the electric drift field inside the sensor layer. The reduction of diffusion by a magnetic field is well known for gases. With realistic assumptions for the mean free path of charge carriers in semiconductors, a similar effect should be observable in solid state materials. We placed a Medipix-2 detector in the magnetic field of a medical MR device with a maximum magnetic field of 3 T and illuminated it with photons and α-particles from 241Am. We observe that with a magnetic field of 3000 mT the mean cluster size is reduced by 0.75 %.

Physical characterization and performance comparison of active- and passive-pixel CMOS detectors for mammography.

PubMed

Elbakri, I A; McIntosh, B J; Rickey, D W

2009-03-21

We investigated the physical characteristics of two complementary metal oxide semiconductor (CMOS) mammography detectors. The detectors featured 14-bit image acquisition, 50 microm detector element (del) size and an active area of 5 cm x 5 cm. One detector was a passive-pixel sensor (PPS) with signal amplification performed by an array of amplifiers connected to dels via data lines. The other detector was an active-pixel sensor (APS) with signal amplification performed at each del. Passive-pixel designs have higher read noise due to data line capacitance, and the APS represents an attempt to improve the noise performance of this technology. We evaluated the detectors' resolution by measuring the modulation transfer function (MTF) using a tilted edge. We measured the noise power spectra (NPS) and detective quantum efficiencies (DQE) using mammographic beam conditions specified by the IEC 62220-1-2 standard. Our measurements showed the APS to have much higher gain, slightly higher MTF, and higher NPS. The MTF of both sensors approached 10% near the Nyquist limit. DQE values near dc frequency were in the range of 55-67%, with the APS sensor DQE lower than the PPS DQE for all frequencies. Our results show that lower read noise specifications in this case do not translate into gains in the imaging performance of the sensor. We postulate that the lower fill factor of the APS is a possible cause for this result.

On the possibility to use semiconductive hybrid pixel detectors for study of radiation belt of the Earth.

NASA Astrophysics Data System (ADS)

Guskov, A.; Shelkov, G.; Smolyanskiy, P.; Zhemchugov, A.

2016-02-01

The scientific apparatus GAMMA-400 designed for study of electromagnetic and hadron components of cosmic rays will be launched to an elliptic orbit with the apogee of about 300 000 km and the perigee of about 500 km. Such a configuration of the orbit allows it to cross periodically the radiation belt and the outer part of magnetosphere. We discuss the possibility to use hybrid pixel detecters based on the Timepix chip and semiconductive sensors on board the GAMMA-400 apparatus. Due to high granularity of the sensor (pixel size is 55 mum) and possibility to measure independently an energy deposition in each pixel, such compact and lightweight detector could be a unique instrument for study of spatial, energy and time structure of electron and proton components of the radiation belt.

Novel Hybrid CMOS X-ray Detector Developments for Future Large Area and High Resolution X-ray Astronomy Missions

NASA Astrophysics Data System (ADS)

Falcone, Abe

In the coming years, X-ray astronomy will require new soft X-ray detectors that can be read very quickly with low noise and can achieve small pixel sizes over a moderately large focal plane area. These requirements will be present for a variety of X-ray missions that will attempt to address science that was highly ranked by the 2010 Decadal Survey, including missions with science that overlaps with that of IXO and Athena, as well as other missions addressing science topics beyond those of IXO and Athena. An X-ray Surveyor mission was recently chosen by NASA for study by a Science & Technology Definition Team (STDT) so it can be considered as an option for an upcom-ing flagship mission. A mission such as this was endorsed by the NASA long term planning document entitled "Enduring Quests, Daring Visions," and a detailed description of one possible reali-zation of such a mission has been referred to as SMART-X, which was described in a recent NASA RFI response. This provides an example of a future mission concept with these requirements since it has high X-ray throughput and excellent spatial resolution. We propose to continue to modify current active pixel sensor designs, in particular the hybrid CMOS detectors that we have been working with for several years, and implement new in-pixel technologies that will allow us to achieve these ambitious and realistic requirements on a timeline that will make them available to upcoming X-ray missions. This proposal is a continuation of our program that has been work-ing on these developments for the past several years. The first 3 years of the program led to the development of a new circuit design for each pixel, which has now been shown to be suitable for a larger detector array. The proposed activity for the next four years will be to incorporate this pixel design into a new design of a full detector array (2k×2k pixels with digital output) and to fabricate this full-sized device so it can be thoroughly tested and characterized.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Lan, E-mail: lgao@pppl.gov; Hill, K. W.; Bitter, M.

A high spatial resolution of a few μm is often required for probing small-scale high-energy-density plasmas using high resolution x-ray imaging spectroscopy. This resolution can be achieved by adjusting system magnification to overcome the inherent limitation of the detector pixel size. Laboratory experiments on investigating the relation between spatial resolution and system magnification for a spherical crystal spectrometer are presented. Tungsten Lβ{sub 2} rays from a tungsten-target micro-focus x-ray tube were diffracted by a Ge 440 crystal, which was spherically bent to a radius of 223 mm, and imaged onto an x-ray CCD with 13-μm pixel size. The source-to-crystal (p)more » and crystal-to-detector (q) distances were varied to produce spatial magnifications (M = q/p) ranging from 2 to 10. The inferred instrumental spatial width reduces with increasing system magnification M. However, the experimental measurement at each M is larger than the theoretical value of pixel size divided by M. Future work will focus on investigating possible broadening mechanisms that limit the spatial resolution.« less

Spatial resolution of a spherical x-ray crystal spectrometer at various magnifications

DOE PAGES

Gao, Lan; Hill, K. W.; Bitter, M.; ...

2016-08-23

Here, a high spatial resolution of a few μm is often required for probing small-scale high-energy-density plasmas using high resolution x-ray imaging spectroscopy. This resolution can be achieved by adjusting system magnification to overcome the inherent limitation of the detector pixel size. Laboratory experiments on investigating the relation between spatial resolution and system magnification for a spherical crystal spectrometer are presented. Tungsten Lβ 2 rays from a tungsten-target micro-focus x-ray tube were diffracted by a Ge 440 crystal, which was spherically bent to a radius of 223 mm, and imaged onto an x-ray CCD with 13-μm pixel size. The source-to-crystalmore » (p) and crystal-to-detector (q) distances were varied to produce spatial magnifications ( M = q/p) ranging from 2 to 10. The inferred instrumental spatial width reduces with increasing system magnification M. However, the experimental measurement at each M is larger than the theoretical value of pixel size divided by M. Future work will focus on investigating possible broadening mechanisms that limit the spatial resolution.« less

Building large area CZT imaging detectors for a wide-field hard X-ray telescope—ProtoEXIST1

NASA Astrophysics Data System (ADS)

Hong, J.; Allen, B.; Grindlay, J.; Chammas, N.; Barthelemy, S.; Baker, R.; Gehrels, N.; Nelson, K. E.; Labov, S.; Collins, J.; Cook, W. R.; McLean, R.; Harrison, F.

2009-07-01

We have constructed a moderately large area (32cm), fine pixel (2.5 mm pixel, 5 mm thick) CZT imaging detector which constitutes the first section of a detector module (256cm) developed for a balloon-borne wide-field hard X-ray telescope, ProtoEXIST1. ProtoEXIST1 is a prototype for the High Energy Telescope (HET) in the Energetic X-ray imaging Survey Telescope (EXIST), a next generation space-borne multi-wavelength telescope. We have constructed a large (nearly gapless) detector plane through a modularization scheme by tiling of a large number of 2cm×2cm CZT crystals. Our innovative packaging method is ideal for many applications such as coded-aperture imaging, where a large, continuous detector plane is desirable for the optimal performance. Currently we have been able to achieve an energy resolution of 3.2 keV (FWHM) at 59.6 keV on average, which is exceptional considering the moderate pixel size and the number of detectors in simultaneous operation. We expect to complete two modules (512cm) within the next few months as more CZT becomes available. We plan to test the performance of these detectors in a near space environment in a series of high altitude balloon flights, the first of which is scheduled for Fall 2009. These detector modules are the first in a series of progressively more sophisticated detector units and packaging schemes planned for ProtoEXIST2 & 3, which will demonstrate the technology required for the advanced CZT imaging detectors (0.6 mm pixel, 4.5m area) required in EXIST/HET.

Electron crystallography with the EIGER detector

PubMed Central

Tinti, Gemma; Fröjdh, Erik; van Genderen, Eric; Gruene, Tim; Schmitt, Bernd; de Winter, D. A. Matthijs; Weckhuysen, Bert M.; Abrahams, Jan Pieter

2018-01-01

Electron crystallography is a discipline that currently attracts much attention as method for inorganic, organic and macromolecular structure solution. EIGER, a direct-detection hybrid pixel detector developed at the Paul Scherrer Institut, Switzerland, has been tested for electron diffraction in a transmission electron microscope. EIGER features a pixel pitch of 75 × 75 µm2, frame rates up to 23 kHz and a dead time between frames as low as 3 µs. Cluster size and modulation transfer functions of the detector at 100, 200 and 300 keV electron energies are reported and the data quality is demonstrated by structure determination of a SAPO-34 zeotype from electron diffraction data. PMID:29765609

Small pixel cross-talk MTF and its impact on MWIR sensor performance

NASA Astrophysics Data System (ADS)

Goss, Tristan M.; Willers, Cornelius J.

2017-05-01

As pixel sizes reduce in the development of modern High Definition (HD) Mid Wave Infrared (MWIR) detectors the interpixel cross-talk becomes increasingly difficult to regulate. The diffusion lengths required to achieve the quantum efficiency and sensitivity of MWIR detectors are typically longer than the pixel pitch dimension, and the probability of inter-pixel cross-talk increases as the pixel pitch/diffusion length fraction decreases. Inter-pixel cross-talk is most conveniently quantified by the focal plane array sampling Modulation Transfer Function (MTF). Cross-talk MTF will reduce the ideal sinc square pixel MTF that is commonly used when modelling sensor performance. However, cross-talk MTF data is not always readily available from detector suppliers, and since the origins of inter-pixel cross-talk are uniquely device and manufacturing process specific, no generic MTF models appear to satisfy the needs of the sensor designers and analysts. In this paper cross-talk MTF data has been collected from recent publications and the development for a generic cross-talk MTF model to fit this data is investigated. The resulting cross-talk MTF model is then included in a MWIR sensor model and the impact on sensor performance is evaluated in terms of the National Imagery Interoperability Rating Scale's (NIIRS) General Image Quality Equation (GIQE) metric for a range of fnumber/ detector pitch Fλ/d configurations and operating environments. By applying non-linear boost transfer functions in the signal processing chain, the contrast losses due to cross-talk may be compensated for. Boost transfer functions, however, also reduce the signal to noise ratio of the sensor. In this paper boost function limits are investigated and included in the sensor performance assessments.

Particle tracking with a Timepix based triple GEM detector

NASA Astrophysics Data System (ADS)

George, S. P.; Murtas, F.; Alozy, J.; Curioni, A.; Rosenfeld, A. B.; Silari, M.

2015-11-01

This paper details the response of a triple GEM detector with a 55 μmetre pitch pixelated ASIC for readout. The detector is operated as a micro TPC with 9.5 cm3 sensitive volume and characterized with a mixed beam of 120 GeV protons and positive pions. A process for reconstruction of incident particle tracks from individual ionization clusters is described and scans of the gain and drift fields are performed. The angular resolution of the measured tracks is characterized. Also, the readout was operated in a mixed mode where some pixels measure drift time and others charge. This was used to measure the energy deposition in the detector and the charge cloud size as a function of interaction depth. The future uses of the device, including in microdosimetry are discussed.

Measurements with MÖNCH, a 25 μm pixel pitch hybrid pixel detector

NASA Astrophysics Data System (ADS)

Ramilli, M.; Bergamaschi, A.; Andrae, M.; Brückner, M.; Cartier, S.; Dinapoli, R.; Fröjdh, E.; Greiffenberg, D.; Hutwelker, T.; Lopez-Cuenca, C.; Mezza, D.; Mozzanica, A.; Ruat, M.; Redford, S.; Schmitt, B.; Shi, X.; Tinti, G.; Zhang, J.

2017-01-01

MÖNCH is a hybrid silicon pixel detector based on charge integration and with analog readout, featuring a pixel size of 25×25 μm2. The latest working prototype consists of an array of 400×400 identical pixels for a total active area of 1×1 cm2. Its design is optimized for the single photon regime. An exhaustive characterization of this large area prototype has been carried out in the past months, and it confirms an ENC in the order of 35 electrons RMS and a dynamic range of ~4×12 keV photons in high gain mode, which increases to ~100×12 keV photons with the lowest gain setting. The low noise levels of MÖNCH make it a suitable candidate for X-ray detection at energies around 1 keV and below. Imaging applications in particular can benefit significantly from the use of MÖNCH: due to its extremely small pixel pitch, the detector intrinsically offers excellent position resolution. Moreover, in low flux conditions, charge sharing between neighboring pixels allows the use of position interpolation algorithms which grant a resolution at the micrometer-level. Its energy reconstruction and imaging capabilities have been tested for the first time at a low energy beamline at PSI, with photon energies between 1.75 keV and 3.5 keV, and results will be shown.

Large Area Cd0.9Zn0.1Te Pixelated Detector: Fabrication and Characterization

NASA Astrophysics Data System (ADS)

Chaudhuri, Sandeep K.; Nguyen, Khai; Pak, Rahmi O.; Matei, Liviu; Buliga, Vladimir; Groza, Michael; Burger, Arnold; Mandal, Krishna C.

2014-04-01

Cd0.9Zn0.1Te (CZT) based pixelated radiation detectors have been fabricated and characterized for gamma ray detection. Large area CZT single crystals has been grown using a tellurium solvent method. A 10 ×10 guarded pixelated detector has been fabricated on a 19.5 ×19.5 ×5 mm3 crystal cut out from the grown ingot. The pixel dimensions were 1.3 ×1.3 mm2 and were pitched at 1.8 mm. A guard grid was used to reduce interpixel/inter-electrode leakage. The crystal was characterized in planar configuration using electrical, optical and optoelectronic methods prior to the fabrication of pixelated geometry. Current-voltage (I-V) measurements revealed a leakage current of 27 nA at an operating bias voltage of 1000 V and a resistivity of 3.1 ×1010 Ω-cm. Infrared transmission imaging revealed an average tellurium inclusion/precipitate size less than 8 μm. Pockels measurement has revealed a near-uniform depth-wise distribution of the internal electric field. The mobility-lifetime product in this crystal was calculated to be 6.2 ×10 - 3 cm2/V using alpha ray spectroscopic method. Gamma spectroscopy using a 137Cs source on the pixelated structure showed fully resolved 662 keV gamma peaks for all the pixels, with percentage resolution (FWHM) as high as 1.8%.

Performance of a Medipix3RX spectroscopic pixel detector with a high resistivity gallium arsenide sensor.

PubMed

Hamann, Elias; Koenig, Thomas; Zuber, Marcus; Cecilia, Angelica; Tyazhev, Anton; Tolbanov, Oleg; Procz, Simon; Fauler, Alex; Baumbach, Tilo; Fiederle, Michael

2015-03-01

High resistivity gallium arsenide is considered a suitable sensor material for spectroscopic X-ray imaging detectors. These sensors typically have thicknesses between a few hundred μm and 1 mm to ensure a high photon detection efficiency. However, for small pixel sizes down to several tens of μm, an effect called charge sharing reduces a detector's spectroscopic performance. The recently developed Medipix3RX readout chip overcomes this limitation by implementing a charge summing circuit, which allows the reconstruction of the full energy information of a photon interaction in a single pixel. In this work, we present the characterization of the first Medipix3RX detector assembly with a 500 μm thick high resistivity, chromium compensated gallium arsenide sensor. We analyze its properties and demonstrate the functionality of the charge summing mode by means of energy response functions recorded at a synchrotron. Furthermore, the imaging properties of the detector, in terms of its modulation transfer functions and signal-to-noise ratios, are investigated. After more than one decade of attempts to establish gallium arsenide as a sensor material for photon counting detectors, our results represent a breakthrough in obtaining detector-grade material. The sensor we introduce is therefore suitable for high resolution X-ray imaging applications.

Energy weighted x-ray dark-field imaging.

PubMed

Pelzer, Georg; Zang, Andrea; Anton, Gisela; Bayer, Florian; Horn, Florian; Kraus, Manuel; Rieger, Jens; Ritter, Andre; Wandner, Johannes; Weber, Thomas; Fauler, Alex; Fiederle, Michael; Wong, Winnie S; Campbell, Michael; Meiser, Jan; Meyer, Pascal; Mohr, Jürgen; Michel, Thilo

2014-10-06

The dark-field image obtained in grating-based x-ray phase-contrast imaging can provide information about the objects' microstructures on a scale smaller than the pixel size even with low geometric magnification. In this publication we demonstrate that the dark-field image quality can be enhanced with an energy-resolving pixel detector. Energy-resolved x-ray dark-field images were acquired with a 16-energy-channel photon-counting pixel detector with a 1 mm thick CdTe sensor in a Talbot-Lau x-ray interferometer. A method for contrast-noise-ratio (CNR) enhancement is proposed and validated experimentally. In measurements, a CNR improvement by a factor of 1.14 was obtained. This is equivalent to a possible radiation dose reduction of 23%.

Design methodology: edgeless 3D ASICs with complex in-pixel processing for pixel detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fahim Farah, Fahim Farah; Deptuch, Grzegorz W.; Hoff, James R.

The design methodology for the development of 3D integrated edgeless pixel detectors with in-pixel processing using Electronic Design Automation (EDA) tools is presented. A large area 3 tier 3D detector with one sensor layer and two ASIC layers containing one analog and one digital tier, is built for x-ray photon time of arrival measurement and imaging. A full custom analog pixel is 65μm x 65μm. It is connected to a sensor pixel of the same size on one side, and on the other side it has approximately 40 connections to the digital pixel. A 32 x 32 edgeless array withoutmore » any peripheral functional blocks constitutes a sub-chip. The sub-chip is an indivisible unit, which is further arranged in a 6 x 6 array to create the entire 1.248cm x 1.248cm ASIC. Each chip has 720 bump-bond I/O connections, on the back of the digital tier to the ceramic PCB. All the analog tier power and biasing is conveyed through the digital tier from the PCB. The assembly has no peripheral functional blocks, and hence the active area extends to the edge of the detector. This was achieved by using a few flavors of almost identical analog pixels (minimal variation in layout) to allow for peripheral biasing blocks to be placed within pixels. The 1024 pixels within a digital sub-chip array have a variety of full custom, semi-custom and automated timing driven functional blocks placed together. The methodology uses a modified mixed-mode on-top digital implementation flow to not only harness the tool efficiency for timing and floor-planning but also to maintain designer control over compact parasitically aware layout. The methodology uses the Cadence design platform, however it is not limited to this tool.« less

Design methodology: edgeless 3D ASICs with complex in-pixel processing for pixel detectors

NASA Astrophysics Data System (ADS)

Fahim, Farah; Deptuch, Grzegorz W.; Hoff, James R.; Mohseni, Hooman

2015-08-01

The design methodology for the development of 3D integrated edgeless pixel detectors with in-pixel processing using Electronic Design Automation (EDA) tools is presented. A large area 3 tier 3D detector with one sensor layer and two ASIC layers containing one analog and one digital tier, is built for x-ray photon time of arrival measurement and imaging. A full custom analog pixel is 65μm x 65μm. It is connected to a sensor pixel of the same size on one side, and on the other side it has approximately 40 connections to the digital pixel. A 32 x 32 edgeless array without any peripheral functional blocks constitutes a sub-chip. The sub-chip is an indivisible unit, which is further arranged in a 6 x 6 array to create the entire 1.248cm x 1.248cm ASIC. Each chip has 720 bump-bond I/O connections, on the back of the digital tier to the ceramic PCB. All the analog tier power and biasing is conveyed through the digital tier from the PCB. The assembly has no peripheral functional blocks, and hence the active area extends to the edge of the detector. This was achieved by using a few flavors of almost identical analog pixels (minimal variation in layout) to allow for peripheral biasing blocks to be placed within pixels. The 1024 pixels within a digital sub-chip array have a variety of full custom, semi-custom and automated timing driven functional blocks placed together. The methodology uses a modified mixed-mode on-top digital implementation flow to not only harness the tool efficiency for timing and floor-planning but also to maintain designer control over compact parasitically aware layout. The methodology uses the Cadence design platform, however it is not limited to this tool.

Development of X-Ray Microcalorimeter Imaging Spectrometers for the X-Ray Surveyor Mission Concept

NASA Technical Reports Server (NTRS)

Bandler, Simon R.; Adams, Joseph S.; Chervenak, James A.; Datesman, Aaron M.; Eckart, Megan E.; Finkbeiner, Fred M.; Kelley, Richard L.; Kilbourne, Caroline A.; Betncourt-Martinez, Gabriele; Miniussi, Antoine R.;

Biological tissue imaging with a position and time sensitive pixelated detector.

PubMed

Jungmann, Julia H; Smith, Donald F; MacAleese, Luke; Klinkert, Ivo; Visser, Jan; Heeren, Ron M A

2012-10-01

We demonstrate the capabilities of a highly parallel, active pixel detector for large-area, mass spectrometric imaging of biological tissue sections. A bare Timepix assembly (512 × 512 pixels) is combined with chevron microchannel plates on an ion microscope matrix-assisted laser desorption time-of-flight mass spectrometer (MALDI TOF-MS). The detector assembly registers position- and time-resolved images of multiple m/z species in every measurement frame. We prove the applicability of the detection system to biomolecular mass spectrometry imaging on biologically relevant samples by mass-resolved images from Timepix measurements of a peptide-grid benchmark sample and mouse testis tissue slices. Mass-spectral and localization information of analytes at physiologic concentrations are measured in MALDI-TOF-MS imaging experiments. We show a high spatial resolution (pixel size down to 740 × 740 nm(2) on the sample surface) and a spatial resolving power of 6 μm with a microscope mode laser field of view of 100-335 μm. Automated, large-area imaging is demonstrated and the Timepix' potential for fast, large-area image acquisition is highlighted.

Investigation of CMOS pixel sensor with 0.18 μm CMOS technology for high-precision tracking detector

NASA Astrophysics Data System (ADS)

Zhang, L.; Fu, M.; Zhang, Y.; Yan, W.; Wang, M.

2017-01-01

The Circular Electron Positron Collider (CEPC) proposed by the Chinese high energy physics community is aiming to measure Higgs particles and their interactions precisely. The tracking detector including Silicon Inner Tracker (SIT) and Forward Tracking Disks (FTD) has driven stringent requirements on sensor technologies in term of spatial resolution, power consumption and readout speed. CMOS Pixel Sensor (CPS) is a promising candidate to approach these requirements. This paper presents the preliminary studies on the sensor optimization for tracking detector to achieve high collection efficiency while keeping necessary spatial resolution. Detailed studies have been performed on the charge collection using a 0.18 μm CMOS image sensor process. This process allows high resistivity epitaxial layer, leading to a significant improvement on the charge collection and therefore improving the radiation tolerance. Together with the simulation results, the first exploratory prototype has bee designed and fabricated. The prototype includes 9 different pixel arrays, which vary in terms of pixel pitch, diode size and geometry. The total area of the prototype amounts to 2 × 7.88 mm2.

Results from a 64-pixel PIN-diode detector system for low-energy beta-electrons

NASA Astrophysics Data System (ADS)

Wuestling, Sascha; Fraenkle, F.; Habermehl, F.; Renschler, P.; Steidl, M.

2010-12-01

The KATRIN neutrino mass experiment is based on a precise energy measurement (Δ E/ E=5×10 -5) of electrons emerging from tritium beta decay ( Emax=18.6 keV). This is done by a large electrostatic retarding spectrometer (MAC-E Filter), which is followed by an electron detector. Key requirements for this detector are a large sensitive area (˜80 cm 2), a certain energy resolution (Δ E=600 eV @ 18.6 keV) but also a certain spatial resolution (˜3 mm), which leads to a multi-pixel design. As a tentative design on the way to the final detector, but also for operational service on the so-called pre-spectrometer experiment, a detector system with a reduced size (16 cm 2) and a reduced pixel number (64), making use of a monolithic segmented silicon PIN diode, was designed and built. While the design and very first measurements have been presented in Wuestling et al. [6], this publication shows the operational performance of the detector system. The robust concept of the electronics allowed adaptation to mechanically different experimental setups. The spacial resolution of the detector system proved to be essential in examining Penning trap induced background and other effects in the pre-spectrometer experiment. The detector performance test runs include energy resolution and calibration, background rates, correlation between pixels (crosstalk), spatially resolved rate analysis, and a dead-layer measurement [7]. The detector allows for background searches with a sensitivity as low as 1.3×10 -3 cps/cm 2 in the energy range of 20 keV. This allows the pre-spectrometer to be characterized with e-gun illumination with a signal to background ratio of better than 10 5 and the search for ultra low Penning discharge emissions.

High resolution 1280×1024, 15 μm pitch compact InSb IR detector with on-chip ADC

NASA Astrophysics Data System (ADS)

Nesher, O.; Pivnik, I.; Ilan, E.; Calalhorra, Z.; Koifman, A.; Vaserman, I.; Oiknine Schlesinger, J.; Gazit, R.; Hirsh, I.

2009-05-01

Over the last decade, SCD has developed and manufactured high quality InSb Focal Plane Arrays (FPAs), which are currently used in many applications worldwide. SCD's production line includes many different types of InSb FPA with formats of 320x256, 480x384 and 640x512 elements and with pitch sizes in the range of 15 to 30 μm. All these FPAs are available in various packaging configurations, including fully integrated Detector-Dewar-Cooler Assemblies (DDCA) with either closed-cycle Sterling or open-loop Joule-Thomson coolers. With an increasing need for higher resolution, SCD has recently developed a new large format 2-D InSb detector with 1280x1024 elements and a pixel size of 15μm. The InSb 15μm pixel technology has already been proven at SCD with the "Pelican" detector (640x512 elements), which was introduced at the Orlando conference in 2006. A new signal processor was developed at SCD for use in this mega-pixel detector. This Readout Integrated Circuit (ROIC) is designed for, and manufactured with, 0.18 μm CMOS technology. The migration from 0.5 to 0.18 μm CMOS technology supports SCD's roadmap for the reduction of pixel size and power consumption and is in line with the increasing demand for improved performance and on-chip functionality. Consequently, the new ROIC maintains the same level of performance and functionality with a 15 μm pitch, as exists in our 20 μm-pitch ROICs based on 0.5μm CMOS technology. Similar to Sebastian (SCD ROIC with A/D on chip), this signal processor also includes A/D converters on the chip and demonstrates the same level of performance, but with reduced power consumption. The pixel readout rate has been increased up to 160 MHz in order to support a high frame rate, resulting in 120 Hz operation with a window of 1024×1024 elements at ~130 mW. These A/D converters on chip save the need for using 16 A/D channels on board (in the case of an analog ROIC) which would operate at 10 MHz and consume about 8Watts A Dewar has been designed with a stiffened detector support to withstand harsh environmental conditions with a minimal contribution to the heat load of the detector. The combination of the 0.18μm-based low power CMOS technology for the ROIC and the stiffening of the detector support within the Dewar has enabled the use of the Ricor K508 cryo-cooler (0.5 W). This has created a high-resolution detector in a very compact package. In this paper we present the basic concept of the new detector. We will describe its construction and will present electrical and radiometric characterization results.

Evaluation of resolution and periodic errors of a flatbed scanner used for digitizing spectroscopic photographic plates

PubMed Central

Wyatt, Madison; Nave, Gillian

2017-01-01

We evaluated the use of a commercial flatbed scanner for digitizing photographic plates used for spectroscopy. The scanner has a bed size of 420 mm by 310 mm and a pixel size of about 0.0106 mm. Our tests show that the closest line pairs that can be resolved with the scanner are 0.024 mm apart, only slightly larger than the Nyquist resolution of 0.021 mm expected by the 0.0106 mm pixel size. We measured periodic errors in the scanner using both a calibrated length scale and a photographic plate. We find no noticeable periodic errors in the direction parallel to the linear detector in the scanner, but errors with an amplitude of 0.03 mm to 0.05 mm in the direction perpendicular to the detector. We conclude that large periodic errors in measurements of spectroscopic plates using flatbed scanners can be eliminated by scanning the plates with the dispersion direction parallel to the linear detector by placing the plate along the short side of the scanner. PMID:28463262

Characterization of pixelated TlBr detectors with Tl electrodes

NASA Astrophysics Data System (ADS)

Hitomi, Keitaro; Onodera, Toshiyuki; Kim, Seong-Yun; Shoji, Tadayoshi; Ishii, Keizo

2014-05-01

A 4.36-mm-thick pixelated thallium bromide (TlBr) detector with Tl electrodes was fabricated from a crystal grown by the traveling molten zone method using zone-purified material. The detector had four 1×1 mm2 pixelated anodes. The detector performance was characterized at room temperature. The mobility-lifetime products of electrons for each pixel of the TlBr detector were measured to be >2.8×10-3 cm2/V. The four pixelated anodes of the detector exhibited energy resolutions of 1.5-1.8% full width at half maximum (FWHM) for 662-keV gamma rays for single-pixel events with the depth correction method. An energy resolution of 4.5% FWHM for 662-keV gamma rays was obtained from a reconstructed energy spectrum using two-pixel events from the two pixelated anodes on the detector.

Towards simultaneous single emission microscopy and magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Cai, Liang

In recent years, the combined nuclear imaging and magnetic resonance imaging (MRI) has drawn extensive research effort. They can provide simultaneously acquired anatomical and functional information inside the human/small animal body in vivo. In this dissertation, the development of an ultrahigh resolution MR-compatible SPECT (Single Photon Emission Computed Tomography) system that can be operated inside a pre-existing clinical MR scanner for simultaneous dual-modality imaging of small animals will be discussed. This system is constructed with 40 small pixel CdTe detector modules assembled in a fully stationary ring SPECT geometry. Series of experiments have demonstrated that this system is capable of providing an imaging resolution of <500?m, when operated inside MR scanners. The ultrahigh resolution MR-compatible SPECT system is built around a small pixel CdTe detector module that we recently developed. Each module consists of CdTe detectors having an overall size of 2.2 cm x 1.1 cm, divided into 64 x 32 pixels of 350 mum in size. A novel hybrid pixel-waveform (HPWF) readout system is also designed to alleviate several challenges for using small-pixel CdTe detectors in ultrahigh-resolution SPECT imaging applications. The HPWF system utilizes a modified version of a 2048-channel 2-D CMOS ASIC to readout the anode pixel, and a digitizing circuitry to sample the signal waveform induced on the cathode. The cathode waveform acquired with the HPWF circuitry offers excellent spatial resolution, energy resolution and depth of interaction (DOI) information, even with the presence of excessive charge-sharing/charge-loss between the small anode pixels. The HPWF CdTe detector is designed and constructed with a minimum amount of ferromagnetic materials, to ensure the MR-compatibility. To achieve sub-500?m imaging resolution, two special designed SPECT apertures have been constructed with different pinhole sizes of 300?m and 500?m respectively. It has 40 pinhole inserts that are made of cast platinum (90%)-iridium (10%) alloy, which provides the maximum stopping power and are compatible with MR scanners. The SPECT system is installed on a non-metal gantry constructed with 3-D printing using nylon powder material. This compact system can work as a "low-cost" desktop ultrahigh resolution SPECT system. It can also be directly operated inside an MR scanner. Accurate system geometrical calibration and corresponding image reconstruction methods for the MRC-SPECT system is developed. In order to account for the magnetic field induced distortion in the SPECT image, a comprehensive charge collection model inside strong magnetic field is adopted to produce high resolution SPECT image inside MR scanner.

Silicon pixel R&D for CLIC

NASA Astrophysics Data System (ADS)

Munker, M.

2017-01-01

Challenging detector requirements are imposed by the physics goals at the future multi-TeV e+ e- Compact Linear Collider (CLIC). A single point resolution of 3 μm for the vertex detector and 7 μm for the tracker is required. Moreover, the CLIC vertex detector and tracker need to be extremely light weighted with a material budget of 0.2% X0 per layer in the vertex detector and 1-2% X0 in the tracker. A fast time slicing of 10 ns is further required to suppress background from beam-beam interactions. A wide range of sensor and readout ASIC technologies are investigated within the CLIC silicon pixel R&D effort. Various hybrid planar sensor assemblies with a pixel size of 25×25 μm2 and 55×55 μm2 have been produced and characterised by laboratory measurements and during test-beam campaigns. Experimental and simulation results for thin (50 μm-500 μm) slim edge and active-edge planar, and High-Voltage CMOS sensors hybridised to various readout ASICs (Timepix, Timepix3, CLICpix) are presented.

The Belle II DEPFET pixel detector

NASA Astrophysics Data System (ADS)

Moser, Hans-Günther; DEPFET Collaboration

2016-09-01

The Belle II experiment at KEK (Tsukuba, Japan) will explore heavy flavour physics (B, charm and tau) at the starting of 2018 with unprecedented precision. Charged particles are tracked by a two-layer DEPFET pixel device (PXD), a four-layer silicon strip detector (SVD) and the central drift chamber (CDC). The PXD will consist of two layers at radii of 14 mm and 22 mm with 8 and 12 ladders, respectively. The pixel sizes will vary, between 50 μm×(55-60) μm in the first layer and between 50 μm×(70-85) μm in the second layer, to optimize the charge sharing efficiency. These innermost layers have to cope with high background occupancy, high radiation and must have minimal material to reduce multiple scattering. These challenges are met using the DEPFET technology. Each pixel is a FET integrated on a fully depleted silicon bulk. The signal charge collected in the 'internal gate' modulates the FET current resulting in a first stage amplification and therefore very low noise. This allows very thin sensors (75 μm) reducing the overall material budget of the detector (0.21% X0). Four fold multiplexing of the column parallel readout allows read out a full frame of the pixel matrix in only 20 μs while keeping the power consumption low enough for air cooling. Only the active electronics outside the detector acceptance has to be cooled actively with a two phase CO2 system. Furthermore the DEPFET technology offers the unique feature of an electronic shutter which allows the detector to operate efficiently in the continuous injection mode of superKEKB.

The Infrared Astronomical Satellite /IRAS/ Scientific Data Analysis System /SDAS/ sky flux subsystem

NASA Technical Reports Server (NTRS)

Stagner, J. R.; Girard, M. A.

1980-01-01

The sky flux subsystem of the Infrared Astronomical Satellite Scientific Data Analysis System is described. Its major output capabilities are (1) the all-sky lune maps (8-arcminute pixel size), (2) galactic plane maps (2-arcminute pixel size) and (3) regional maps of small areas such as extended sources greater than 1-degree in extent. The major processing functions are to (1) merge the CRDD and pointing data, (2) phase the detector streams, (3) compress the detector streams in the in-scan and cross-scan directions, and (4) extract data. Functional diagrams of the various capabilities of the subsystem are given. Although this device is inherently nonimaging, various calibrated and geometrically controlled imaging products are created, suitable for quantitative and qualitative scientific interpretation.

Laboratory and testbeam results for thin and epitaxial planar sensors for HL-LHC

DOE PAGES

Bubna, M.; Bolla, G.; Bortoletto, D.; ...

2015-08-03

The High-Luminosity LHC (HL-LHC) upgrade of the CMS pixel detector will require the development of novel pixel sensors which can withstand the increase in instantaneous luminosity to L = 5 × 10 34 cm –2s –1 and collect ~ 3000fb –1 of data. The innermost layer of the pixel detector will be exposed to doses of about 10 16 n eq/ cm 2. Hence, new pixel sensors with improved radiation hardness need to be investigated. A variety of silicon materials (Float-zone, Magnetic Czochralski and Epitaxially grown silicon), with thicknesses from 50 μm to 320 μm in p-type and n-type substrates have beenmore » fabricated using single-sided processing. The effect of reducing the sensor active thickness to improve radiation hardness by using various techniques (deep diffusion, wafer thinning, or growing epitaxial silicon on a handle wafer) has been studied. Furthermore, the results for electrical characterization, charge collection efficiency, and position resolution of various n-on-p pixel sensors with different substrates and different pixel geometries (different bias dot gaps and pixel implant sizes) will be presented.« less

Characterization of chromium compensated GaAs as an X-ray sensor material for charge-integrating pixel array detectors

NASA Astrophysics Data System (ADS)

Becker, J.; Tate, M. W.; Shanks, K. S.; Philipp, H. T.; Weiss, J. T.; Purohit, P.; Chamberlain, D.; Gruner, S. M.

2018-01-01

We studied the properties of chromium compensated GaAs when coupled to charge integrating ASICs as a function of detector temperature, applied bias and X-ray tube energy. The material is a photoresistor and can be biased to collect either electrons or holes by the pixel circuitry. Both are studied here. Previous studies have shown substantial hole trapping. This trapping and other sensor properties give rise to several non-ideal effects which include an extended point spread function, variations in the effective pixel size, and rate dependent offset shifts. The magnitude of these effects varies with temperature and bias, mandating good temperature uniformity in the sensor and very good temperature stabilization, as well as a carefully selected bias voltage.

The low energy detector of Simbol-X

NASA Astrophysics Data System (ADS)

Lechner, P.; Andricek, L.; Briel, U.; Hasinger, G.; Heinzinger, K.; Herrmann, S.; Huber, H.; Kendziorra, E.; Lauf, T.; Lutz, G.; Richter, R.; Santangelo, A.; Schaller, G.; Schnecke, M.; Schopper, F.; Segneri, G.; Strüder, L.; Treis, J.

2008-07-01

Simbol-X is a French-Italian-German hard energy X-ray mission with a projected launch in 2014. Being sensitive in the energy range from 500 eV to 80 keV it will cover the sensitivity gap beyond the energy interval of today's telescopes XMM-Newton and Chandra. Simbol-X will use an imaging telescope of nested Wolter-I mirrors. To provide a focal length of 20 m it will be the first mission of two independent mirror and detector spacecrafts in autonomous formation flight. The detector spacecraft's payload is composed of an imaging silicon low energy detector in front of a pixelated cadmium-telluride hard energy detector. Both have a sensitive area of 8 × 8 cm2 to cover a 12 arcmin field of view and a pixel size of 625 × 625 μm2 adapted to the telescope's resolution of 20 arcsec. The additional LED specifications are: high energy resolution, high quantum efficiency, fast readout and optional window mode, monolithic device with 100 % fill factor and suspension mounting, and operation at warm temperature. To match these requirements the low energy detector is composed of 'active macro pixels', combining the large, scalable area of a Silicon Drift Detector and the low-noise, on-demand readout of an integrated DEPFET amplifier. Flight representative prototypes have been processed at the MPI semiconductor laboratory, and the prototype's measured performance demonstrates the technology readiness.

Compressive hyperspectral sensor for LWIR gas detection

NASA Astrophysics Data System (ADS)

Russell, Thomas A.; McMackin, Lenore; Bridge, Bob; Baraniuk, Richard

2012-06-01

Focal plane arrays with associated electronics and cooling are a substantial portion of the cost, complexity, size, weight, and power requirements of Long-Wave IR (LWIR) imagers. Hyperspectral LWIR imagers add significant data volume burden as they collect a high-resolution spectrum at each pixel. We report here on a LWIR Hyperspectral Sensor that applies Compressive Sensing (CS) in order to achieve benefits in these areas. The sensor applies single-pixel detection technology demonstrated by Rice University. The single-pixel approach uses a Digital Micro-mirror Device (DMD) to reflect and multiplex the light from a random assortment of pixels onto the detector. This is repeated for a number of measurements much less than the total number of scene pixels. We have extended this architecture to hyperspectral LWIR sensing by inserting a Fabry-Perot spectrometer in the optical path. This compressive hyperspectral imager collects all three dimensions on a single detection element, greatly reducing the size, weight and power requirements of the system relative to traditional approaches, while also reducing data volume. The CS architecture also supports innovative adaptive approaches to sensing, as the DMD device allows control over the selection of spatial scene pixels to be multiplexed on the detector. We are applying this advantage to the detection of plume gases, by adaptively locating and concentrating target energy. A key challenge in this system is the diffraction loss produce by the DMD in the LWIR. We report the results of testing DMD operation in the LWIR, as well as system spatial and spectral performance.

WE-AB-207A-01: BEST IN PHYSICS (IMAGING): High-Resolution Cone-Beam CT of the Extremities and Cancellous Bone Architecture with a CMOS Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Q; Brehler, M; Sisniega, A

Purpose: Extremity cone-beam CT (CBCT) with an amorphous silicon (aSi) flat-panel detector (FPD) provides low-dose volumetric imaging with high spatial resolution. We investigate the performance of the newer complementary metal-oxide semiconductor (CMOS) detectors to enhance resolution of extremities CBCT to ∼0.1 mm, enabling morphological analysis of trabecular bone. Quantitative in-vivo imaging of bone microarchitecture could present an important advance for osteoporosis and osteoarthritis diagnosis and therapy assessment. Methods: Cascaded systems models of CMOS- and FPD-based extremities CBCT were implemented. Performance was compared for a range of pixel sizes (0.05–0.4 mm), focal spot sizes (0.3–0.6 FS), and x-ray techniques (0.05–0.8 mAs/projection)more » using detectability of high-, low-, and all-frequency tasks for a nonprewhitening observer. Test-bench implementation of CMOS-based extremity CBCT involved a Teledyne DALSA Xineos3030HR detector with 0.099 mm pixels and a compact rotating anode x-ray source with 0.3 FS (IMD RTM37). Metrics of bone morphology obtained using CMOS-based CBCT were compared in cadaveric specimens to FPD-based system using a Varian PaxScan4030 (0.194 mm pixels). Results: Finer pixel size and reduced electronic noise for CMOS (136 e compared to 2000 e for FPD) resulted in ∼1.9× increase in detectability for high-frequency tasks and ∼1.1× increase for all-frequency tasks. Incorporation of the new x-ray source with reduced focal spot size (0.3 FS vs. 0.5 FS used on current extremities CBCT) improved detectability for CMOS-based CBCT by ∼1.7× for high-frequency tasks. Compared to FPD CBCT, the CMOS detector yielded improved agreement with micro-CT in measurements of trabecular thickness (∼1.7× reduction in relative error), bone volume (∼1.5× reduction), and trabecular spacing (∼3.5× reduction). Conclusion: Imaging performance modelling and experimentation indicate substantial improvements for high-frequency imaging tasks through adoption of the CMOS detector and small FS x-ray source, motivating the use of these components in a new system for quantitative in-vivo imaging of trabecular bone. Financial Support: US NIH grant R01EB018896. Qian Cao is a Howard Hughes Medical Institute International Student Research Fellow. Disclosures: W Zbijewski, J Siewerdsen and A Sisniega receive research funding from Carestream Health.« less

Advanced processing of CdTe pixel radiation detectors

NASA Astrophysics Data System (ADS)

Gädda, A.; Winkler, A.; Ott, J.; Härkönen, J.; Karadzhinova-Ferrer, A.; Koponen, P.; Luukka, P.; Tikkanen, J.; Vähänen, S.

2017-12-01

We report a fabrication process of pixel detectors made of bulk cadmium telluride (CdTe) crystals. Prior to processing, the quality and defect density in CdTe material was characterized by infrared (IR) spectroscopy. The semiconductor detector and Flip-Chip (FC) interconnection processing was carried out in the clean room premises of Micronova Nanofabrication Centre in Espoo, Finland. The chip scale processes consist of the aluminum oxide (Al2O3) low temperature thermal Atomic Layer Deposition (ALD), titanium tungsten (TiW) metal sputtering depositions and an electroless Nickel growth. CdTe crystals with the size of 10×10×0.5 mm3 were patterned with several photo-lithography techniques. In this study, gold (Au) was chosen as the material for the wettable Under Bump Metalization (UBM) pads. Indium (In) based solder bumps were grown on PSI46dig read out chips (ROC) having 4160 pixels within an area of 1 cm2. CdTe sensor and ROC were hybridized using a low temperature flip-chip (FC) interconnection technique. The In-Au cold weld bonding connections were successfully connecting both elements. After the processing the detector packages were wire bonded into associated read out electronics. The pixel detectors were tested at the premises of Finnish Radiation Safety Authority (STUK). During the measurement campaign, the modules were tested by exposure to a 137Cs source of 1.5 TBq for 8 minutes. We detected at the room temperature a photopeak at 662 keV with about 2 % energy resolution.

Verification of intensity modulated profiles using a pixel segmented liquid-filled linear array.

PubMed

Pardo, J; Roselló, J V; Sánchez-Doblado, F; Gómez, F

2006-06-07

A liquid isooctane (C8H18) filled ionization chamber linear array developed for radiotherapy quality assurance, consisting of 128 pixels (each of them with a 1.7 mm pitch), has been used to acquire profiles of several intensity modulated fields. The results were compared with film measurements using the gamma test. The comparisons show a very good matching, even in high gradient dose regions. The volume-averaging effect of the pixels is negligible and the spatial resolution is enough to verify these regions. However, some mismatches between the detectors have been found in regions where low-energy scattered photons significantly contribute to the total dose. These differences are not very important (in fact, the measurements of both detectors are in agreement using the gamma test with tolerances of 3% and 3 mm in most of those regions), and may be associated with the film energy dependence. In addition, the linear array repeatability (0.27% one standard deviation) is much better than the film one ( approximately 3%). The good repeatability, small pixel size and high spatial resolution make the detector ideal for the real time profile verification of high gradient beam profiles like those present in intensity modulated radiation therapy and radiosurgery.

Characterization of Pixelated Cadmium-Zinc-Telluride Detectors for Astrophysical Applications

NASA Technical Reports Server (NTRS)

Gaskin, Jessica; Sharma, Dharma; Ramsey, Brian; Seller, Paul

2003-01-01

Comparisons of charge sharing and charge loss measurements between two pixelated Cadmium-Zinc-Telluride (CdZnTe) detectors are discussed. These properties along with the detector geometry help to define the limiting energy resolution and spatial resolution of the detector in question. The first detector consists of a 1-mm-thick piece of CdZnTe sputtered with a 4x4 array of pixels with pixel pitch of 750 microns (inter-pixel gap is 100 microns). Signal readout is via discrete ultra-low-noise preamplifiers, one for each of the 16 pixels. The second detector consists of a 2-mm-thick piece of CdZnTe sputtered with a 16x16 array of pixels with a pixel pitch of 300 microns (inter-pixel gap is 50 microns). This crystal is bonded to a custom-built readout chip (ASIC) providing all front-end electronics to each of the 256 independent pixels. These detectors act as precursors to that which will be used at the focal plane of the High Energy Replicated Optics (HERO) telescope currently being developed at Marshall Space Flight Center. With a telescope focal length of 6 meters, the detector needs to have a spatial resolution of around 200 microns in order to take full advantage of the HERO angular resolution. We discuss to what degree charge sharing will degrade energy resolution but will improve our spatial resolution through position interpolation.

Task-based modeling and optimization of a cone-beam CT scanner for musculoskeletal imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prakash, P.; Zbijewski, W.; Gang, G. J.

2011-10-15

Purpose: This work applies a cascaded systems model for cone-beam CT imaging performance to the design and optimization of a system for musculoskeletal extremity imaging. The model provides a quantitative guide to the selection of system geometry, source and detector components, acquisition techniques, and reconstruction parameters. Methods: The model is based on cascaded systems analysis of the 3D noise-power spectrum (NPS) and noise-equivalent quanta (NEQ) combined with factors of system geometry (magnification, focal spot size, and scatter-to-primary ratio) and anatomical background clutter. The model was extended to task-based analysis of detectability index (d') for tasks ranging in contrast and frequencymore » content, and d' was computed as a function of system magnification, detector pixel size, focal spot size, kVp, dose, electronic noise, voxel size, and reconstruction filter to examine trade-offs and optima among such factors in multivariate analysis. The model was tested quantitatively versus the measured NPS and qualitatively in cadaver images as a function of kVp, dose, pixel size, and reconstruction filter under conditions corresponding to the proposed scanner. Results: The analysis quantified trade-offs among factors of spatial resolution, noise, and dose. System magnification (M) was a critical design parameter with strong effect on spatial resolution, dose, and x-ray scatter, and a fairly robust optimum was identified at M {approx} 1.3 for the imaging tasks considered. The results suggested kVp selection in the range of {approx}65-90 kVp, the lower end (65 kVp) maximizing subject contrast and the upper end maximizing NEQ (90 kVp). The analysis quantified fairly intuitive results--e.g., {approx}0.1-0.2 mm pixel size (and a sharp reconstruction filter) optimal for high-frequency tasks (bone detail) compared to {approx}0.4 mm pixel size (and a smooth reconstruction filter) for low-frequency (soft-tissue) tasks. This result suggests a specific protocol for 1 x 1 (full-resolution) projection data acquisition followed by full-resolution reconstruction with a sharp filter for high-frequency tasks along with 2 x 2 binning reconstruction with a smooth filter for low-frequency tasks. The analysis guided selection of specific source and detector components implemented on the proposed scanner. The analysis also quantified the potential benefits and points of diminishing return in focal spot size, reduced electronic noise, finer detector pixels, and low-dose limits of detectability. Theoretical results agreed quantitatively with the measured NPS and qualitatively with evaluation of cadaver images by a musculoskeletal radiologist. Conclusions: A fairly comprehensive model for 3D imaging performance in cone-beam CT combines factors of quantum noise, system geometry, anatomical background, and imaging task. The analysis provided a valuable, quantitative guide to design, optimization, and technique selection for a musculoskeletal extremities imaging system under development.« less

Design of the low area monotonic trim DAC in 40 nm CMOS technology for pixel readout chips

NASA Astrophysics Data System (ADS)

Drozd, A.; Szczygiel, R.; Maj, P.; Satlawa, T.; Grybos, P.

2014-12-01

The recent research in hybrid pixel detectors working in single photon counting mode focuses on nanometer or 3D technologies which allow making pixels smaller and implementing more complex solutions in each of the pixels. Usually single pixel in readout electronics for X-ray detection comprises of charge amplifier, shaper and discriminator that allow classification of events occurring at the detector as true or false hits by comparing amplitude of the signal obtained with threshold voltage, which minimizes the influence of noise effects. However, making the pixel size smaller often causes problems with pixel to pixel uniformity and additional effects like charge sharing become more visible. To improve channel-to-channel uniformity or implement an algorithm for charge sharing effect minimization, small area trimming DACs working in each pixel independently are necessary. However, meeting the requirement of small area often results in poor linearity and even non-monotonicity. In this paper we present a novel low-area thermometer coded 6-bit DAC implemented in 40 nm CMOS technology. Monte Carlo simulations were performed on the described design proving that under all conditions designed DAC is inherently monotonic. Presented DAC was implemented in the prototype readout chip with 432 pixels working in single photon counting mode, with two trimming DACs in each pixel. Each DAC occupies the area of 8 μm × 18.5 μm. Measurements and chips' tests were performed to obtain reliable statistical results.

Multichroic Bolometric Detector Architecture for Cosmic Microwave Background Polarimetry Experiments

NASA Astrophysics Data System (ADS)

Suzuki, Aritoki

Characterization of the Cosmic Microwave Background (CMB) B-mode polarization signal will test models of inflationary cosmology, as well as constrain the sum of the neutrino masses and other cosmological parameters. The low intensity of the B-mode signal combined with the need to remove polarized galactic foregrounds requires a sensitive millimeter receiver and effective methods of foreground removal. Current bolometric detector technology is reaching the sensitivity limit set by the CMB photon noise. Thus, we need to increase the optical throughput to increase an experiment's sensitivity. To increase the throughput without increasing the focal plane size, we can increase the frequency coverage of each pixel. Increased frequency coverage per pixel has additional advantage that we can split the signal into frequency bands to obtain spectral information. The detection of multiple frequency bands allows for removal of the polarized foreground emission from synchrotron radiation and thermal dust emission, by utilizing its spectral dependence. Traditionally, spectral information has been captured with a multi-chroic focal plane consisting of a heterogeneous mix of single-color pixels. To maximize the efficiency of the focal plane area, we developed a multi-chroic pixel. This increases the number of pixels per frequency with same focal plane area. We developed multi-chroic antenna-coupled transition edge sensor (TES) detector array for the CMB polarimetry. In each pixel, a silicon lens-coupled dual polarized sinuous antenna collects light over a two-octave frequency band. The antenna couples the broadband millimeter wave signal into microstrip transmission lines, and on-chip filter banks split the broadband signal into several frequency bands. Separate TES bolometers detect the power in each frequency band and linear polarization. We will describe the design and performance of these devices and present optical data taken with prototype pixels and detector arrays. Our measurements show beams with percent level ellipticity, percent level cross-polarization leakage, and partitioned bands using banks of two and three filters. We will also describe the development of broadband anti-reflection coatings for the high dielectric constant lens. The broadband anti-reflection coating has approximately 100% bandwidth and no detectable loss at cryogenic temperature. We will describe a next generation CMB polarimetry experiment, the POLARBEAR-2, in detail. The POLARBEAR-2 would have focal planes with kilo-pixel of these detectors to achieve high sensitivity. We'll also introduce proposed experiments that would use multi-chroic detector array we developed in this work. We'll conclude by listing out suggestions for future multichroic detector development.

Micrometer-resolution imaging using MÖNCH: towards G2-less grating interferometry

PubMed Central

Cartier, Sebastian; Kagias, Matias; Bergamaschi, Anna; Wang, Zhentian; Dinapoli, Roberto; Mozzanica, Aldo; Ramilli, Marco; Schmitt, Bernd; Brückner, Martin; Fröjdh, Erik; Greiffenberg, Dominic; Mayilyan, Davit; Mezza, Davide; Redford, Sophie; Ruder, Christian; Schädler, Lukas; Shi, Xintian; Thattil, Dhanya; Tinti, Gemma; Zhang, Jiaguo; Stampanoni, Marco

2016-01-01

MÖNCH is a 25 µm-pitch charge-integrating detector aimed at exploring the limits of current hybrid silicon detector technology. The small pixel size makes it ideal for high-resolution imaging. With an electronic noise of about 110 eV r.m.s., it opens new perspectives for many synchrotron applications where currently the detector is the limiting factor, e.g. inelastic X-ray scattering, Laue diffraction and soft X-ray or high-resolution color imaging. Due to the small pixel pitch, the charge cloud generated by absorbed X-rays is shared between neighboring pixels for most of the photons. Therefore, at low photon fluxes, interpolation algorithms can be applied to determine the absorption position of each photon with a resolution of the order of 1 µm. In this work, the characterization results of one of the MÖNCH prototypes are presented under low-flux conditions. A custom interpolation algorithm is described and applied to the data to obtain high-resolution images. Images obtained in grating interferometry experiments without the use of the absorption grating G2 are shown and discussed. Perspectives for the future developments of the MÖNCH detector are also presented. PMID:27787252

Hit efficiency study of CMS prototype forward pixel detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Dongwook; /Johns Hopkins U.

2006-01-01

In this paper the author describes the measurement of the hit efficiency of a prototype pixel device for the CMS forward pixel detector. These pixel detectors were FM type sensors with PSI46V1 chip readout. The data were taken with the 120 GeV proton beam at Fermilab during the period of December 2004 to February 2005. The detectors proved to be highly efficient (99.27 {+-} 0.02%). The inefficiency was primarily located near the corners of the individual pixels.

Downsampling Photodetector Array with Windowing

NASA Technical Reports Server (NTRS)

Patawaran, Ferze D.; Farr, William H.; Nguyen, Danh H.; Quirk, Kevin J.; Sahasrabudhe, Adit

2012-01-01

In a photon counting detector array, each pixel in the array produces an electrical pulse when an incident photon on that pixel is detected. Detection and demodulation of an optical communication signal that modulated the intensity of the optical signal requires counting the number of photon arrivals over a given interval. As the size of photon counting photodetector arrays increases, parallel processing of all the pixels exceeds the resources available in current application-specific integrated circuit (ASIC) and gate array (GA) technology; the desire for a high fill factor in avalanche photodiode (APD) detector arrays also precludes this. Through the use of downsampling and windowing portions of the detector array, the processing is distributed between the ASIC and GA. This allows demodulation of the optical communication signal incident on a large photon counting detector array, as well as providing architecture amenable to algorithmic changes. The detector array readout ASIC functions as a parallel-to-serial converter, serializing the photodetector array output for subsequent processing. Additional downsampling functionality for each pixel is added to this ASIC. Due to the large number of pixels in the array, the readout time of the entire photodetector is greater than the time between photon arrivals; therefore, a downsampling pre-processing step is done in order to increase the time allowed for the readout to occur. Each pixel drives a small counter that is incremented at every detected photon arrival or, equivalently, the charge in a storage capacitor is incremented. At the end of a user-configurable counting period (calculated independently from the ASIC), the counters are sampled and cleared. This downsampled photon count information is then sent one counter word at a time to the GA. For a large array, processing even the downsampled pixel counts exceeds the capabilities of the GA. Windowing of the array, whereby several subsets of pixels are designated for processing, is used to further reduce the computational requirements. The grouping of the designated pixel frame as the photon count information is sent one word at a time to the GA, the aggregation of the pixels in a window can be achieved by selecting only the designated pixel counts from the serial stream of photon counts, thereby obviating the need to store the entire frame of pixel count in the gate array. The pixel count se quence from each window can then be processed, forming lower-rate pixel statistics for each window. By having this processing occur in the GA rather than in the ASIC, future changes to the processing algorithm can be readily implemented. The high-bandwidth requirements of a photon counting array combined with the properties of the optical modulation being detected by the array present a unique problem that has not been addressed by current CCD or CMOS sensor array solutions.

A micron resolution optical scanner for characterization of silicon detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shukla, R. A.; Dugad, S. R., E-mail: dugad@cern.ch; Gopal, A. V.

2014-02-15

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

First light from a very large area pixel array for high-throughput x-ray polarimetry

NASA Astrophysics Data System (ADS)

Bellazzini, R.; Spandre, G.; Minuti, M.; Baldini, L.; Brez, A.; Cavalca, F.; Latronico, L.; Omodei, N.; Massai, M. M.; Sgrò, C.; Costa, E.; Soffitta, P.; Krummenacher, F.; de Oliveira, R.

2006-06-01

We report on a large active area (15x15mm2), high channel density (470 pixels/mm2), self-triggering CMOS analog chip that we have developed as pixelized charge collecting electrode of a Micropattern Gas Detector. This device, which represents a big step forward both in terms of size and performance, is the last version of three generations of custom ASICs of increasing complexity. The CMOS pixel array has the top metal layer patterned in a matrix of 105600 hexagonal pixels at 50μm pitch. Each pixel is directly connected to the underneath full electronics chain which has been realized in the remaining five metal and single poly-silicon layers of a standard 0.18μm CMOS VLSI technology. The chip has customizable self-triggering capability and includes a signal pre-processing function for the automatic localization of the event coordinates. In this way it is possible to reduce significantly the readout time and the data volume by limiting the signal output only to those pixels belonging to the region of interest. The very small pixel area and the use of a deep sub-micron CMOS technology has brought the noise down to 50 electrons ENC. Results from in depth tests of this device when coupled to a fine pitch (50μm on a triangular pattern) Gas Electron Multiplier are presented. The matching of readout and gas amplification pitch allows getting optimal results. The application of this detector for Astronomical X-Ray Polarimetry is discussed. The experimental detector response to polarized and unpolarized X-ray radiation when working with two gas mixtures and two different photon energies is shown. Results from a full MonteCarlo simulation for several galactic and extragalactic astronomical sources are also reported.

GATE simulation of a new design of pinhole SPECT system for small animal brain imaging

NASA Astrophysics Data System (ADS)

Uzun Ozsahin, D.; Bläckberg, L.; El Fakhri, G.; Sabet, H.

2017-01-01

Small animal SPECT imaging has gained an increased interest over the past decade since it is an excellent tool for developing new drugs and tracers. Therefore, there is a huge effort on the development of cost-effective SPECT detectors with high capabilities. The aim of this study is to simulate the performance characteristics of new designs for a cost effective, stationary SPECT system dedicated to small animal imaging with a focus on mice brain. The conceptual design of this SPECT system platform, Stationary Small Animal SSA-SPECT, is to use many pixelated CsI:TI detector modules with 0.4 mm × 0.4 mm pixels in order to achieve excellent intrinsic detector resolution where each module is backed by a single pinhole collimator with 0.3 mm hole diameter. In this work, we present the simulation results of four variations of the SSA-SPECT platform where the number of detector modules and FOV size is varied while keeping the detector size and collimator hole size constant. Using the NEMA NU-4 protocol, we performed spatial resolution, sensitivity, image quality simulations followed by a Derenzo-like phantom evaluation. The results suggest that all four SSA-SPECT systems can provide better than 0.063% system sensitivity and < 1.5 mm FWHM spatial resolution without resolution recovery or other correction techniques. Specifically, SSA-SPECT-1 showed a system sensitivity of 0.09% in combination with 1.1 mm FWHM spatial resolution.

Electromagnetic Considerations for Planar Bolometer Arrays in the Single Mode Limit

NASA Technical Reports Server (NTRS)

Wollack, Edward J.; Chuss, David T.; Moseley, Samuel

2006-01-01

Filled arrays of planar bolometers are finding astronomical applications at wavelengths as long as several millimeters. In an effort to keep focal planes to a reasonable size while maintaining large numbers of detectors, a common strategy is to push these arrays to operate close to or at the single mode limit. Doing so introduces several new challenges that are not experienced in the multi-mode case of far-infrared detectors having similar pixel sizes. First, diffractive effects of the pixels themselves are no longer insignificant and will ultimately contribute to the resolution limit of the optical system in which they reside. We use the method of Withlngton et al. (2003) to model the polarized diffraction in this limit. Second, it is necessary to re-examine the coupling between the radiation and the absorbing element that is thermally connected to the bolometers. The small f-numbers that are often employed to make use of large focal planes makes backshort construction problematic. We introduce a new strategy to increase detector efficiency that uses an antireflective layer on the front side of the detector array. In addition, typical methods for stray light control that rely on multiple reflections in a lossy medium fail due to physical size constraints. For this application, we find that resonant absorbers are a more effective strategy that can be implemented in the space available.

Applications of a pnCCD detector coupled to columnar structure CsI(Tl) scintillator system in ultra high energy X-ray Laue diffraction

NASA Astrophysics Data System (ADS)

Shokr, M.; Schlosser, D.; Abboud, A.; Algashi, A.; Tosson, A.; Conka, T.; Hartmann, R.; Klaus, M.; Genzel, C.; Strüder, L.; Pietsch, U.

2017-12-01

Most charge coupled devices (CCDs) are made of silicon (Si) with typical active layer thicknesses of several microns. In case of a pnCCD detector the sensitive Si thickness is 450 μm. However, for silicon based detectors the quantum efficiency for hard X-rays drops significantly for photon energies above 10 keV . This drawback can be overcome by combining a pixelated silicon-based detector system with a columnar scintillator. Here we report on the characterization of a low noise, fully depleted 128×128 pixels pnCCD detector with 75×75 μm2 pixel size coupled to a 700 μm thick columnar CsI(Tl) scintillator in the photon range between 1 keV to 130 keV . The excellent performance of the detection system in the hard X-ray range is demonstrated in a Laue type X-ray diffraction experiment performed at EDDI beamline of the BESSY II synchrotron taken at a set of several GaAs single crystals irradiated by white synchrotron radiation. With the columnar structure of the scintillator, the position resolution of the whole system reaches a value of less than one pixel. Using the presented detector system and considering the functional relation between indirect and direct photon events Laue diffraction peaks with X-ray energies up to 120 keV were efficiently detected. As one of possible applications of the combined CsI-pnCCD system we demonstrate that the accuracy of X-ray structure factors extracted from Laue diffraction peaks can be significantly improved in hard X-ray range using the combined CsI(Tl)-pnCCD system compared to a bare pnCCD.

AO wavefront sensing detector developments at ESO

NASA Astrophysics Data System (ADS)

Downing, Mark; Kolb, Johann; Baade, Dietrich; Iwert, Olaf; Hubin, Norbert; Reyes, Javier; Feautrier, Philippe; Gach, Jean-Luc; Balard, Philippe; Guillaume, Christian; Stadler, Eric; Magnard, Yves

2010-07-01

The detector is a critical component of any Adaptive Optics WaveFront Sensing (AO WFS) system. The required combination of fast frame rate, high quantum efficiency, low noise, large number and size of pixels, and low image lag can often only be met by specialized custom developments. ESO's very active WFS detector development program is described. Key test results are presented for newly developed detectors: a) the e2v L3Vision CCD220 (the fastest/lowest noise AO detector to date) to be deployed soon on 2nd Generation VLT instruments, and b) the MPI-HLL pnCCD with its superb high "red" response. The development of still more advanced laser/natural guide-star WFS detectors is critical for the feasibility of ESO's EELT. The paper outlines: a) the multi-phased development plan that will ensure detectors are available on-time for EELT first-light AO systems, b) results of design studies performed by industry during 2007 including a comparison of the most promising technologies, c) results from CMOS technology demonstrators that were built and tested over the past two years to assess and validate various technologies at the pixel level, their fulfillment of critical requirements (especially read noise and speed), and scalability to full-size. The next step will be towards Scaled-Down Demonstrators (SDD) to retire architecture and process risks. The SDD will be large enough to be used for E-ELT first-light AO WFS systems. For full operability, 30-50 full-scale devices will be needed.

The EIGER detector for low-energy electron microscopy and photoemission electron microscopy.

PubMed

Tinti, G; Marchetto, H; Vaz, C A F; Kleibert, A; Andrä, M; Barten, R; Bergamaschi, A; Brückner, M; Cartier, S; Dinapoli, R; Franz, T; Fröjdh, E; Greiffenberg, D; Lopez-Cuenca, C; Mezza, D; Mozzanica, A; Nolting, F; Ramilli, M; Redford, S; Ruat, M; Ruder, Ch; Schädler, L; Schmidt, Th; Schmitt, B; Schütz, F; Shi, X; Thattil, D; Vetter, S; Zhang, J

2017-09-01

EIGER is a single-photon-counting hybrid pixel detector developed at the Paul Scherrer Institut, Switzerland. It is designed for applications at synchrotron light sources with photon energies above 5 keV. Features of EIGER include a small pixel size (75 µm × 75 µm), a high frame rate (up to 23 kHz), a small dead-time between frames (down to 3 µs) and a dynamic range up to 32-bit. In this article, the use of EIGER as a detector for electrons in low-energy electron microscopy (LEEM) and photoemission electron microscopy (PEEM) is reported. It is demonstrated that, with only a minimal modification to the sensitive part of the detector, EIGER is able to detect electrons emitted or reflected by the sample and accelerated to 8-20 keV. The imaging capabilities are shown to be superior to the standard microchannel plate detector for these types of applications. This is due to the much higher signal-to-noise ratio, better homogeneity and improved dynamic range. In addition, the operation of the EIGER detector is not affected by radiation damage from electrons in the present energy range and guarantees more stable performance over time. To benchmark the detector capabilities, LEEM experiments are performed on selected surfaces and the magnetic and electronic properties of individual iron nanoparticles with sizes ranging from 8 to 22 nm are detected using the PEEM endstation at the Surface/Interface Microscopy (SIM) beamline of the Swiss Light Source.

Performance quantification of a millimeter-wavelength imaging system based on inexpensive glow-discharge-detector focal-plane array.

PubMed

Shilemay, Moshe; Rozban, Daniel; Levanon, Assaf; Yitzhaky, Yitzhak; Kopeika, Natan S; Yadid-Pecht, Orly; Abramovich, Amir

2013-03-01

Inexpensive millimeter-wavelength (MMW) optical digital imaging raises a challenge of evaluating the imaging performance and image quality because of the large electromagnetic wavelengths and pixel sensor sizes, which are 2 to 3 orders of magnitude larger than those of ordinary thermal or visual imaging systems, and also because of the noisiness of the inexpensive glow discharge detectors that compose the focal-plane array. This study quantifies the performances of this MMW imaging system. Its point-spread function and modulation transfer function were investigated. The experimental results and the analysis indicate that the image quality of this MMW imaging system is limited mostly by the noise, and the blur is dominated by the pixel sensor size. Therefore, the MMW image might be improved by oversampling, given that noise reduction is achieved. Demonstration of MMW image improvement through oversampling is presented.

Study of the properties of new SPM detectors

NASA Astrophysics Data System (ADS)

Stewart, A. G.; Greene-O'Sullivan, E.; Herbert, D. J.; Saveliev, V.; Quinlan, F.; Wall, L.; Hughes, P. J.; Mathewson, A.; Jackson, J. C.

2006-02-01

The operation and performance of multi-pixel, Geiger-mode APD structures referred to as Silicon Photomultiplier (SPM) are reported. The SPM is a solid state device that has emerged over the last decade as a promising alternative to vacuum PMTs. This is due to their comparable performance in addition to their lower bias operation and power consumption, insensitivity to magnetic fields and ambient light, smaller size and ruggedness. Applications for these detectors are numerous and include life sciences, nuclear medicine, particle physics, microscopy and general instrumentation. With SPM devices, many geometrical and device parameters can be adjusted to optimize their performance for a particular application. In this paper, Monte Carlo simulations and experimental results for 1mm2 SPM structures are reported. In addition, trade-offs involved in optimizing the SPM in terms of the number and size of pixels for a given light intensity, and its affect on the dynamic range are discussed.

Characterisation of novel thin n-in-p planar pixel modules for the ATLAS Inner Tracker upgrade

NASA Astrophysics Data System (ADS)

Beyer, J.-C.; La Rosa, A.; Macchiolo, A.; Nisius, R.; Savic, N.; Taibah, R.

2018-01-01

In view of the high luminosity phase of the LHC (HL-LHC) to start operation around 2026, a major upgrade of the tracker system for the ATLAS experiment is in preparation. The expected neutron equivalent fluence of up to 2.4×1016 1 MeV neq./cm2 at the innermost layer of the pixel detector poses the most severe challenge. Thanks to their low material budget and high charge collection efficiency after irradiation, modules made of thin planar pixel sensors are promising candidates to instrument these layers. To optimise the sensor layout for the decreased pixel cell size of 50×50 μm2, TCAD device simulations are being performed to investigate the charge collection efficiency before and after irradiation. In addition, sensors of 100-150 μm thickness, interconnected to FE-I4 read-out chips featuring the previous generation pixel cell size of 50×250 μm2, are characterised with testbeams at the CERN-SPS and DESY facilities. The performance of sensors with various designs, irradiated up to a fluence of 1×1016 neq./cm2, is compared in terms of charge collection and hit efficiency. A replacement of the two innermost pixel layers is foreseen during the lifetime of HL-LHC . The replacement will require several months of intervention, during which the remaining detector modules cannot be cooled. They are kept at room temperature, thus inducing an annealing. The performance of irradiated modules will be investigated with testbeam campaigns and the method of accelerated annealing at higher temperatures.

Small Pixel Hybrid CMOS X-ray Detectors

NASA Astrophysics Data System (ADS)

Hull, Samuel; Bray, Evan; Burrows, David N.; Chattopadhyay, Tanmoy; Falcone, Abraham; Kern, Matthew; McQuaide, Maria; Wages, Mitchell

2018-01-01

Concepts for future space-based X-ray observatories call for a large effective area and high angular resolution instrument to enable precision X-ray astronomy at high redshift and low luminosity. Hybrid CMOS detectors are well suited for such high throughput instruments, and the Penn State X-ray detector lab, in collaboration with Teledyne Imaging Sensors, has recently developed new small pixel hybrid CMOS X-ray detectors. These prototype 128x128 pixel devices have 12.5 micron pixel pitch, 200 micron fully depleted depth, and include crosstalk eliminating CTIA amplifiers and in-pixel correlated double sampling (CDS) capability. We report on characteristics of these new detectors, including the best read noise ever measured for an X-ray hybrid CMOS detector, 5.67 e- (RMS).

Ground calibration of the spatial response and quantum efficiency of the CdZnTe hard x-ray detectors for NuSTAR

NASA Astrophysics Data System (ADS)

Grefenstette, Brian W.; Bhalerao, Varun; Cook, W. Rick; Harrison, Fiona A.; Kitaguchi, Takao; Madsen, Kristin K.; Mao, Peter H.; Miyasaka, Hiromasa; Rana, Vikram

2017-08-01

Pixelated Cadmium Zinc Telluride (CdZnTe) detectors are currently flying on the Nuclear Spectroscopic Telescope ARray (NuSTAR) NASA Astrophysics Small Explorer. While the pixel pitch of the detectors is ≍ 605 μm, we can leverage the detector readout architecture to determine the interaction location of an individual photon to much higher spatial accuracy. The sub-pixel spatial location allows us to finely oversample the point spread function of the optics and reduces imaging artifacts due to pixelation. In this paper we demonstrate how the sub-pixel information is obtained, how the detectors were calibrated, and provide ground verification of the quantum efficiency of our Monte Carlo model of the detector response.

Interior micro-CT with an offset detector

PubMed Central

Sharma, Kriti Sen; Gong, Hao; Ghasemalizadeh, Omid; Yu, Hengyong; Wang, Ge; Cao, Guohua

2014-01-01

Purpose: The size of field-of-view (FOV) of a microcomputed tomography (CT) system can be increased by offsetting the detector. The increased FOV is beneficial in many applications. All prior investigations, however, have been focused to the case in which the increased FOV after offset-detector acquisition can cover the transaxial extent of an object fully. Here, the authors studied a new problem where the FOV of a micro-CT system, although increased after offset-detector acquisition, still covers an interior region-of-interest (ROI) within the object. Methods: An interior-ROI-oriented micro-CT scan with an offset detector poses a difficult reconstruction problem, which is caused by both detector offset and projection truncation. Using the projection completion techniques, the authors first extended three previous reconstruction methods from offset-detector micro-CT to offset-detector interior micro-CT. The authors then proposed a novel method which combines two of the extended methods using a frequency split technique. The authors tested the four methods with phantom simulations at 9.4%, 18.8%, 28.2%, and 37.6% detector offset. The authors also applied these methods to physical phantom datasets acquired at the same amounts of detector offset from a customized micro-CT system. Results: When the detector offset was small, all reconstruction methods showed good image quality. At large detector offset, the three extended methods gave either visible shading artifacts or high deviation of pixel value, while the authors’ proposed method demonstrated no visible artifacts and minimal deviation of pixel value in both the numerical simulations and physical experiments. Conclusions: For an interior micro-CT with an offset detector, the three extended reconstruction methods can perform well at a small detector offset but show strong artifacts at a large detector offset. When the detector offset is large, the authors’ proposed reconstruction method can outperform the three extended reconstruction methods by suppressing artifacts and maintaining pixel values. PMID:24877826

Laser pixelation of thick scintillators for medical imaging applications: x-ray studies

NASA Astrophysics Data System (ADS)

Sabet, Hamid; Kudrolli, Haris; Marton, Zsolt; Singh, Bipin; Nagarkar, Vivek V.

2013-09-01

To achieve high spatial resolution required in nuclear imaging, scintillation light spread has to be controlled. This has been traditionally achieved by introducing structures in the bulk of scintillation materials; typically by mechanical pixelation of scintillators and fill the resultant inter-pixel gaps by reflecting materials. Mechanical pixelation however, is accompanied by various cost and complexity issues especially for hard, brittle and hygroscopic materials. For example LSO and LYSO, hard and brittle scintillators of interest to medical imaging community, are known to crack under thermal and mechanical stress; the material yield drops quickly with large arrays with high aspect ratio pixels and therefore the pixelation process cost increases. We are utilizing a novel technique named Laser Induced Optical Barriers (LIOB) for pixelation of scintillators that overcomes the issues associated with mechanical pixelation. In this technique, we can introduce optical barriers within the bulk of scintillator crystals to form pixelated arrays with small pixel size and large thickness. We applied LIOB to LYSO using a high-frequency solid-state laser. Arrays with different crystal thickness (5 to 20 mm thick), and pixel size (0.8×0.8 to 1.5×1.5 mm2) were fabricated and tested. The width of the optical barriers were controlled by fine-tuning key parameters such as lens focal spot size and laser energy density. Here we report on LIOB process, its optimization, and the optical crosstalk measurements using X-rays. There are many applications that can potentially benefit from LIOB including but not limited to clinical/pre-clinical PET and SPECT systems, and photon counting CT detectors.

Modulation transfer function of a triangular pixel array detector.

PubMed

Karimzadeh, Ayatollah

2014-07-01

The modulation transfer function (MTF) is the main parameter that is used to evaluate image quality in electro-optical systems. Detector sampling MTF in most electro-optical systems determines the cutoff frequency of the system. The MTF of the detector depends on its pixel shape. In this work, we calculated the MTF of a detector with an equilateral triangular pixel shape. Some new results were found in deriving the MTF for the equilateral triangular pixel shape.

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

NASA Astrophysics Data System (ADS)

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

2017-01-01

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

Status and Plan for The Upgrade of The CMS Pixel Detector

NASA Astrophysics Data System (ADS)

Lu, Rong-Shyang; CMS Collaboration

2016-04-01

The silicon pixel detector is the innermost component of the CMS tracking system and plays a crucial role in the all-silicon CMS tracker. While the current pixel tracker is designed for and performing well at an instantaneous luminosity of up to 1 ×1034cm-2s-1, it can no longer be operated efficiently at significantly higher values. Based on the strong performance of the LHC accelerator, it is anticipated that peak luminosities of two times the design luminosity are likely to be reached before 2018 and perhaps significantly exceeded in the running period until 2022, referred to as LHC Run 3. Therefore, an upgraded pixel detector, referred to as the phase 1 upgrade, is planned for the year-end technical stop in 2016. With a new pixel readout chip (ROC), an additional fourth layer, two additional endcap disks, and a significantly reduced material budget the upgraded pixel detector will be able to sustain the efficiency of the pixel tracker at the increased requirements imposed by high luminosities and pile-up. The main new features of the upgraded pixel detector will be an ultra-light mechanical design, a digital readout chip with higher rate capability and a new cooling system. These and other design improvements, along with results of Monte Carlo simulation studies for the expected performance of the new pixel detector, will be discussed and compared to those of the current CMS detector.

A High Resolution TDI CCD Camera forMicrosatellite (HRCM)

NASA Astrophysics Data System (ADS)

Hao, Yuncai; Zheng, You; Dong, Ying; Li, Tao; Yu, Shijie

In resent years it is a important development direction in the commercial remote sensing field to obtain (1-5)m high ground resolution from space using microsatellite. Thanks to progress of new technologies, new materials and new detectors it is possible to develop 1m ground resolution space imaging system with weight less than 20kg. Based on many years works on optical system design a project of very high resolution TDI CCD camera using in space was proposed by the authors of this paper. The performance parameters and optical lay-out of the HRCM was presented. A compact optical design and results analysis for the system was given in the paper also. and small fold mirror to take a line field of view usable for TDI CCD and short outer size. The length along the largest size direction is about 1/4 of the focal length. And two 4096X96(grades) line TDI CCD will be used as the focal plane detector. The special optical parts are fixed near before the final image for getting the ground pixel resolution higher than the Nyquist resolution of the detector using the sub-pixel technique which will be explained in the paper. In the system optical SiC will be used as the mirror material, the C-C composite material will be used as the material of the mechanical structure framework. The circle frame of the primary and secondary mirrors will use one time turning on a machine tool in order to assuring concentric request for alignment of the system. In general the HRCM have the performance parameters with 2.5m focal length, 20 FOV, 1/11relative aperture, (0.4-0.8) micrometer spectral range, 10 micron pixel size of TDI CCD, weight less than 20kg, 1m ground pixel resolution at flying orbit 500km high. Design and analysis of the HRCM put up in the paper indicate that HRCM have many advantages to use it in space. Keywords High resolution TDI CCD Sub-pixel imaging Light-weighted optical system SiC mirror

Status and Construction of the Belle II DEPFET pixel system

NASA Astrophysics Data System (ADS)

Lütticke, Florian

2014-06-01

DEpleted P-channel Field Effect Transistor (DEPFET) active pixel detectors combine detection with a first amplification stage in a fully depleted detector, resulting in an superb signal-to-noise ratio even for thin sensors. Two layers of thin (75 micron) silicon DEPFET pixels will be used as the innermost vertex system, very close to the beam pipe in the Belle II detector at the SuperKEKB facility. The status of the 8 million DEPFET pixels detector, latest developments and current system tests will be discussed.

High Dynamic Range Pixel Array Detector for Scanning Transmission Electron Microscopy.

PubMed

Tate, Mark W; Purohit, Prafull; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert; Chang, Celesta S; Deb, Pratiti; Turgut, Emrah; Heron, John T; Schlom, Darrell G; Ralph, Daniel C; Fuchs, Gregory D; Shanks, Katherine S; Philipp, Hugh T; Muller, David A; Gruner, Sol M

2016-02-01

We describe a hybrid pixel array detector (electron microscope pixel array detector, or EMPAD) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128×128 pixel detector consists of a 500 µm thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. This paper describes the detector architecture, data acquisition system, and preliminary results from experiments with 80-200 keV electron beams.

Tracking performance of a single-crystal and a polycrystalline diamond pixel-detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menasce, D.; et al.

2013-06-01

We present a comparative characterization of the performance of a single-crystal and a polycrystalline diamond pixel-detector employing the standard CMS pixel readout chips. Measurements were carried out at the Fermilab Test Beam Facility, FTBF, using protons of momentum 120 GeV/c tracked by a high-resolution pixel telescope. Particular attention was directed to the study of the charge-collection, the charge-sharing among adjacent pixels and the achievable position resolution. The performance of the single-crystal detector was excellent and comparable to the best available silicon pixel-detectors. The measured average detection-efficiency was near unity, ε = 0.99860±0.00006, and the position-resolution for shared hits was aboutmore » 6 μm. On the other hand, the performance of the polycrystalline detector was hampered by its lower charge collection distance and the readout chip threshold. A new readout chip, capable of operating at much lower threshold (around 1 ke $-$), would be required to fully exploit the potential performance of the polycrystalline diamond pixel-detector.« less

Monte Carlo Optimization of Crystal Configuration for Pixelated Molecular SPECT Scanners

NASA Astrophysics Data System (ADS)

Mahani, Hojjat; Raisali, Gholamreza; Kamali-Asl, Alireza; Ay, Mohammad Reza

2017-02-01

Resolution-sensitivity-PDA tradeoff is the most challenging problem in design and optimization of pixelated preclinical SPECT scanners. In this work, we addressed such a challenge from a crystal point-of-view by looking for an optimal pixelated scintillator using GATE Monte Carlo simulation. Various crystal configurations have been investigated and the influence of different pixel sizes, pixel gaps, and three scintillators on tomographic resolution, sensitivity, and PDA of the camera were evaluated. The crystal configuration was then optimized using two objective functions: the weighted-sum and the figure-of-merit methods. The CsI(Na) reveals the highest sensitivity of the order of 43.47 cps/MBq in comparison to the NaI(Tl) and the YAP(Ce), for a 1.5×1.5 mm2 pixel size and 0.1 mm gap. The results show that the spatial resolution, in terms of FWHM, improves from 3.38 to 2.21 mm while the sensitivity simultaneously deteriorates from 42.39 cps/MBq to 27.81 cps/MBq when pixel size varies from 2×2 mm2 to 0.5×0.5 mm2 for a 0.2 mm gap, respectively. The PDA worsens from 0.91 to 0.42 when pixel size decreases from 0.5×0.5 mm2 to 1×1 mm2 for a 0.2 mm gap at 15° incident-angle. The two objective functions agree that the 1.5×1.5 mm2 pixel size and 0.1 mm Epoxy gap CsI(Na) configuration provides the best compromise for small-animal imaging, using the HiReSPECT scanner. Our study highlights that crystal configuration can significantly affect the performance of the camera, and thereby Monte Carlo optimization of pixelated detectors is mandatory in order to achieve an optimal quality tomogram.

Focal Plane Detectors for the Advanced Gamma-Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Otte, A. N.; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Horan, D.; Mukherjee, R.; Smith, A.; Tajima, H.; Wagner, R. G.; Williams, D. A.

2008-12-01

The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation observatory in ground-based very high energy gamma-ray astronomy. Design goals are ten times better sensitivity, higher angular resolution, and a lower energy threshold than existing Cherenkov telescopes. Simulations show that a substantial improvement in angular resolution may be achieved if the pixel diameter is reduced to the order of 0.05 deg, i.e. two to three times smaller than the pixel diameter of current Cherenkov telescope cameras. At these dimensions, photon detectors with smaller physical dimensions can be attractive alternatives to the classical photomultiplier tube (PMT). Furthermore, the operation of an experiment with the size of AGIS requires photon detectors that are among other things more reliable, more durable, and possibly higher efficiency photon detectors. Alternative photon detectors we are considering for AGIS include both silicon photomultipliers (SiPMs) and multi-anode photomultipliers (MAPMTs). Here we present results from laboratory testing of MAPMTs and SiPMs along with results from the first incorporation of these devices into cameras on test bed Cherenkov telescopes.

Dosimetric characterization with 62 MeV protons of a silicon-segmented detector for 2D dose verifications in radiotherapy

NASA Astrophysics Data System (ADS)

Talamonti, C.; Bucciolini, M.; Marrazzo, L.; Menichelli, D.; Bruzzi, M.; Cirrone, G. A. P.; Cuttone, G.; LoJacono, P.

2008-10-01

Due to the features of the modern radiotherapy techniques, namely intensity modulated radiation therapy and proton therapy, where high spatial dose gradients are often present, detectors to be employed for 2D dose verifications have to satisfy very narrow requirements. In particular they have to show high spatial resolution. In the framework of the European Integrated Project—Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology (MAESTRO, no. LSHC-CT-2004-503564), a dosimetric detector adequate for 2D pre-treatment dose verifications was developed. It is a modular detector, based on a monolithic silicon-segmented sensor, with an n-type implantation on an epitaxial p-type layer. Each pixel element is 2×2 mm 2 and the distance center-to-center is 3 mm. The sensor is composed of 21×21 pixels. In this paper, we report the dosimetric characterization of the system with a proton beam. The sensor was irradiated with 62 MeV protons for clinical treatments at INFN-Laboratori Nazionali del Sud (LNS) Catania. The studied parameters were repeatability of a same pixel, response linearity versus absorbed dose, and dose rate and dependence on field size. The obtained results are promising since the performances are within the project specifications.

Using triple gamma coincidences with a pixelated semiconductor Compton-PET scanner: a simulation study

NASA Astrophysics Data System (ADS)

Kolstein, M.; Chmeissani, M.

2016-01-01

The Voxel Imaging PET (VIP) Pathfinder project presents a novel design using pixelated semiconductor detectors for nuclear medicine applications to achieve the intrinsic image quality limits set by physics. The conceptual design can be extended to a Compton gamma camera. The use of a pixelated CdTe detector with voxel sizes of 1 × 1 × 2 mm3 guarantees optimal energy and spatial resolution. However, the limited time resolution of semiconductor detectors makes it impossible to use Time Of Flight (TOF) with VIP PET. TOF is used in order to improve the signal to noise ratio (SNR) by using only the most probable portion of the Line-Of-Response (LOR) instead of its entire length. To overcome the limitation of CdTe time resolution, we present in this article a simulation study using β+-γ emitting isotopes with a Compton-PET scanner. When the β+ annihilates with an electron it produces two gammas which produce a LOR in the PET scanner, while the additional gamma, when scattered in the scatter detector, provides a Compton cone that intersects with the aforementioned LOR. The intersection indicates, within a few mm of uncertainty along the LOR, the origin of the beta-gamma decay. Hence, one can limit the part of the LOR used by the image reconstruction algorithm.

The charge pump PLL clock generator designed for the 1.56 ns bin size time-to-digital converter pixel array of the Timepix3 readout ASIC

NASA Astrophysics Data System (ADS)

Fu, Y.; Brezina, C.; Desch, K.; Poikela, T.; Llopart, X.; Campbell, M.; Massimiliano, D.; Gromov, V.; Kluit, R.; van Beauzekom, M.; Zappon, F.; Zivkovic, V.

2014-01-01

Timepix3 is a newly developed pixel readout chip which is expected to be operated in a wide range of gaseous and silicon detectors. It is made of 256 × 256 pixels organized in a square pixel-array with 55 μm pitch. Oscillators running at 640 MHz are distributed across the pixel-array and allow for a highly accurate measurement of the arrival time of a hit. This paper concentrates on a low-jitter phase locked loop (PLL) that is located in the chip periphery. This PLL provides a control voltage which regulates the actual frequency of the individual oscillators, allowing for compensation of process, voltage, and temperature variations.

Astigmatism correction of a non-imaging double spectrometer fitted with a 2D array detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yaney, P.P.; Ernst, S.L.; Blackshire, J.

1992-12-01

A SPEX 1401 double spectrometer was adapted for a liquid nitrogen cooled CCD detector to permit both spectral and spatial analysis of ceramic specimens in a laser Raman microprobe system. The exit image of the spectrometer suffers from astigmatism due to off-axis spherical mirrors. A cylindrical lens was added before the CCD to correct for the astigmatism. The spectrometer and several lenses were modeled using an optical ray tracing program to characterize the astigmatism and to optimize the locations of the lens and the detector. The astigmatism and the spot pattern sizes determined by the model were in good agreementmore » with he observed performance of the modified spectrometer-detector system. Typical spot patterns fell within the 23 {mu}m square pixel size.« less

Multi-spectral black meta-infrared detectors (Conference Presentation)

NASA Astrophysics Data System (ADS)

Krishna, Sanjay

2016-09-01

There is an increased emphasis on obtaining imaging systems with on-demand spectro-polarimetric information at the pixel level. Meta-infrared detectors in which infrared detectors are combined with metamaterials are a promising way to realize this. The infrared region is appealing due to the low metallic loss, large penetration depth of the localized field and the larger feature sizes compared to the visible region. I will discuss approaches to realize multispectral detectors including our recent work on double metal meta-material design combined with Type II superlattices that have demonstrated enhanced quantum efficiency (collaboration with Padilla group at Duke University).

Track reconstruction for the Mu3e experiment based on a novel Multiple Scattering fit

NASA Astrophysics Data System (ADS)

Kozlinskiy, Alexandr

2017-08-01

The Mu3e experiment is designed to search for the lepton flavor violating decay μ+ → e+e+e-. The aim of the experiment is to reach a branching ratio sensitivity of 10-16. In a first phase the experiment will be performed at an existing beam line at the Paul-Scherrer Institute (Switzerland) providing 108 muons per second, which will allow to reach a sensitivity of 2 · 10-15. The muons with a momentum of about 28 MeV/c are stopped and decay at rest on a target. The decay products (positrons and electrons) with energies below 53MeV are measured by a tracking detector consisting of two double layers of 50 μm thin silicon pixel sensors. The high granularity of the pixel detector with a pixel size of 80 μm × 80 μm allows for a precise track reconstruction in the high multiplicity environment of the Mu3e experiment, reaching 100 tracks per reconstruction frame of 50 ns in the final phase of the experiment. To deal with such high rates and combinatorics, the Mu3e track reconstruction uses a novel fit algorithm that in the simplest case takes into account only the multiple scattering, which allows for a fast online tracking on a GPU based filter farm. An implementation of the 3-dimensional multiple scattering fit based on hit triplets is described. The extension of the fit that takes into account energy losses and pixel size is used for offline track reconstruction. The algorithm and performance of the offline track reconstruction based on a full Geant4 simulation of the Mu3e detector are presented.

Geostationary Coastal and Air Pollution Events (GeoCAPE) Filter Radiometer (FR)

NASA Technical Reports Server (NTRS)

Kotecki, Carl; Chu, Martha; Wilson, Mark; Clark, Mike; Nanan, Bobby; Matson, Liz; McBirney, Dick; Smith, Jay; Earle, Paul; Choi, Mike;

Characterization of a hybrid energy-resolving photon-counting detector

NASA Astrophysics Data System (ADS)

Zang, A.; Pelzer, G.; Anton, G.; Ballabriga Sune, R.; Bisello, F.; Campbell, M.; Fauler, A.; Fiederle, M.; Llopart Cudie, X.; Ritter, I.; Tennert, F.; Wölfel, S.; Wong, W. S.; Michel, T.

2014-03-01

Photon-counting detectors in medical x-ray imaging provide a higher dose efficiency than integrating detectors. Even further possibilities for imaging applications arise, if the energy of each photon counted is measured, as for example K-edge-imaging or optimizing image quality by applying energy weighting factors. In this contribution, we show results of the characterization of the Dosepix detector. This hybrid photon- counting pixel detector allows energy resolved measurements with a novel concept of energy binning included in the pixel electronics. Based on ideas of the Medipix detector family, it provides three different modes of operation: An integration mode, a photon-counting mode, and an energy-binning mode. In energy-binning mode, it is possible to set 16 energy thresholds in each pixel individually to derive a binned energy spectrum in every pixel in one acquisition. The hybrid setup allows using different sensor materials. For the measurements 300 μm Si and 1 mm CdTe were used. The detector matrix consists of 16 x 16 square pixels for CdTe (16 x 12 for Si) with a pixel pitch of 220 μm. The Dosepix was originally intended for applications in the field of radiation measurement. Therefore it is not optimized towards medical imaging. The detector concept itself still promises potential as an imaging detector. We present spectra measured in one single pixel as well as in the whole pixel matrix in energy-binning mode with a conventional x-ray tube. In addition, results concerning the count rate linearity for the different sensor materials are shown as well as measurements regarding energy resolution.

CVD diamond pixel detectors for LHC experiments

NASA Astrophysics Data System (ADS)

Wedenig, R.; Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Knöpfle, K. T.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P. F.; Manfredotti, C.; Marshall, R. D.; Meier, D.; Mishina, M.; Oh, A.; Pan, L. S.; Palmieri, V. G.; Pernicka, M.; Peitz, A.; Pirollo, S.; Polesello, P.; Pretzl, K.; Procario, M.; Re, V.; Riester, J. L.; Roe, S.; Roff, D.; Rudge, A.; Runolfsson, O.; Russ, J.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R. J.; Tesarek, R.; Trawick, M.; Trischuk, W.; Vittone, E.; Wagner, A.; Walsh, A. M.; Weilhammer, P.; White, C.; Zeuner, W.; Ziock, H.; Zoeller, M.; Blanquart, L.; Breugnion, P.; Charles, E.; Ciocio, A.; Clemens, J. C.; Dao, K.; Einsweiler, K.; Fasching, D.; Fischer, P.; Joshi, A.; Keil, M.; Klasen, V.; Kleinfelder, S.; Laugier, D.; Meuser, S.; Milgrome, O.; Mouthuy, T.; Richardson, J.; Sinervo, P.; Treis, J.; Wermes, N.; RD42 Collaboration

1999-08-01

This paper reviews the development of CVD diamond pixel detectors. The preparation of the diamond pixel sensors for bump-bonding to the pixel readout electronics for the LHC and the results from beam tests carried out at CERN are described.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lecomte, Roger; Arpin, Louis; Beaudoin, Jean-Franç

Purpose: LabPET II is a new generation APD-based PET scanner designed to achieve sub-mm spatial resolution using truly pixelated detectors and highly integrated parallel front-end processing electronics. Methods: The basic element uses a 4×8 array of 1.12×1.12 mm{sup 2} Lu{sub 1.9}Y{sub 0.1}SiO{sub 5}:Ce (LYSO) scintillator pixels with one-to-one coupling to a 4×8 pixelated monolithic APD array mounted on a ceramic carrier. Four detector arrays are mounted on a daughter board carrying two flip-chip, 64-channel, mixed-signal, application-specific integrated circuits (ASIC) on the backside interfacing to two detector arrays each. Fully parallel signal processing was implemented in silico by encoding time andmore » energy information using a dual-threshold Time-over-Threshold (ToT) scheme. The self-contained 128-channel detector module was designed as a generic component for ultra-high resolution PET imaging of small to medium-size animals. Results: Energy and timing performance were optimized by carefully setting ToT thresholds to minimize the noise/slope ratio. ToT spectra clearly show resolved 511 keV photopeak and Compton edge with ToT resolution well below 10%. After correction for nonlinear ToT response, energy resolution is typically 24±2% FWHM. Coincidence time resolution between opposing 128-channel modules is below 4 ns FWHM. Initial imaging results demonstrate that 0.8 mm hot spots of a Derenzo phantom can be resolved. Conclusion: A new generation PET scanner featuring truly pixelated detectors was developed and shown to achieve a spatial resolution approaching the physical limit of PET. Future plans are to integrate a small-bore dedicated mouse version of the scanner within a PET/CT platform.« less

Results on 3D interconnection from AIDA WP3

NASA Astrophysics Data System (ADS)

Moser, Hans-Günther; AIDA-WP3

2016-09-01

From 2010 to 2014 the EU funded AIDA project established in one of its work packages (WP3) a network of groups working collaboratively on advanced 3D integration of electronic circuits and semiconductor sensors for applications in particle physics. The main motivation came from the severe requirements on pixel detectors for tracking and vertexing at future Particle Physics experiments at LHC, super-B factories and linear colliders. To go beyond the state-of-the-art, the main issues were studying low mass, high bandwidth applications, with radiation hardness capabilities, with low power consumption, offering complex functionality, with small pixel size and without dead regions. The interfaces and interconnects of sensors to electronic readout integrated circuits are a key challenge for new detector applications.

Coded aperture detector: an image sensor with sub 20-nm pixel resolution.

PubMed

Miyakawa, Ryan; Mayer, Rafael; Wojdyla, Antoine; Vannier, Nicolas; Lesser, Ian; Aron-Dine, Shifrah; Naulleau, Patrick

2014-08-11

We describe the coded aperture detector, a novel image sensor based on uniformly redundant arrays (URAs) with customizable pixel size, resolution, and operating photon energy regime. In this sensor, a coded aperture is scanned laterally at the image plane of an optical system, and the transmitted intensity is measured by a photodiode. The image intensity is then digitally reconstructed using a simple convolution. We present results from a proof-of-principle optical prototype, demonstrating high-fidelity image sensing comparable to a CCD. A 20-nm half-pitch URA fabricated by the Center for X-ray Optics (CXRO) nano-fabrication laboratory is presented that is suitable for high-resolution image sensing at EUV and soft X-ray wavelengths.

Diamond Pixel Detectors

NASA Astrophysics Data System (ADS)

Adam, W.; Berdermann, E.; Bergonzo, P.; Bertuccio, G.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Doroshenko, J.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foster, J.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Gobbi, B.; Grim, G. P.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Koeth, T.; Krammer, M.; Lander, R.; Logiudice, A.; Lu, R.; mac Lynne, L.; Manfredotti, C.; Meier, D.; Mishina, M.; Moroni, L.; Oh, A.; Pan, L. S.; Pernicka, M.; Perera, L.; Pirollo, S.; Plano, R.; Procario, M.; Riester, J. L.; Roe, S.; Rott, C.; Rousseau, L.; Rudge, A.; Russ, J.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R. J.; Tesarek, R.; Trischuk, W.; Tromson, D.; Vittone, E.; Wedenig, R.; Weilhammer, P.; White, C.; Zeuner, W.; Zoeller, M.

2001-06-01

Diamond based pixel detectors are a promising radiation-hard technology for use at the LHC. We present first results on a CMS diamond pixel sensor. With a threshold setting of 2000 electrons, an average pixel efficiency of 78% was obtained for normally incident minimum ionizing particles.

Large Format CMOS-based Detectors for Diffraction Studies

NASA Astrophysics Data System (ADS)

Thompson, A. C.; Nix, J. C.; Achterkirchen, T. G.; Westbrook, E. M.

2013-03-01

Complementary Metal Oxide Semiconductor (CMOS) devices are rapidly replacing CCD devices in many commercial and medical applications. Recent developments in CMOS fabrication have improved their radiation hardness, device linearity, readout noise and thermal noise, making them suitable for x-ray crystallography detectors. Large-format (e.g. 10 cm × 15 cm) CMOS devices with a pixel size of 100 μm × 100 μm are now becoming available that can be butted together on three sides so that very large area detector can be made with no dead regions. Like CCD systems our CMOS systems use a GdOS:Tb scintillator plate to convert stopping x-rays into visible light which is then transferred with a fiber-optic plate to the sensitive surface of the CMOS sensor. The amount of light per x-ray on the sensor is much higher in the CMOS system than a CCD system because the fiber optic plate is only 3 mm thick while on a CCD system it is highly tapered and much longer. A CMOS sensor is an active pixel matrix such that every pixel is controlled and readout independently of all other pixels. This allows these devices to be readout while the sensor is collecting charge in all the other pixels. For x-ray diffraction detectors this is a major advantage since image frames can be collected continuously at up 20 Hz while the crystal is rotated. A complete diffraction dataset can be collected over five times faster than with CCD systems with lower radiation exposure to the crystal. In addition, since the data is taken fine-phi slice mode the 3D angular position of diffraction peaks is improved. We have developed a cooled 6 sensor CMOS detector with an active area of 28.2 × 29.5 cm with 100 μm × 100 μm pixels and a readout rate of 20 Hz. The detective quantum efficiency exceeds 60% over the range 8-12 keV. One, two and twelve sensor systems are also being developed for a variety of scientific applications. Since the sensors are butt able on three sides, even larger systems could be built at reasonable cost.

Development and clinical evaluation of an ionization chamber array with 3.5 mm pixel pitch for quality assurance in advanced radiotherapy techniques.

PubMed

Togno, M; Wilkens, J J; Menichelli, D; Oechsner, M; Perez-Andujar, A; Morin, O

2016-05-01

To characterize a new air vented ionization chamber technology, suitable to build detector arrays with small pixel pitch and independence of sensitivity on dose per pulse. The prototype under test is a linear array of air vented ionization chambers, consisting of 80 pixels with 3.5 mm pixel pitch distance and a sensitive volume of about 4 mm(3). The detector has been characterized with (60)Co radiation and MV x rays from different linear accelerators (with flattened and unflattened beam qualities). Sensitivity dependence on dose per pulse has been evaluated under MV x rays by changing both the source to detector distance and the beam quality. Bias voltage has been varied in order to evaluate the charge collection efficiency in the most critical conditions. Relative dose profiles have been measured for both flattened and unflattened distributions with different field sizes. The reference detectors were a commercial array of ionization chambers and an amorphous silicon flat panel in direct conversion configuration. Profiles of dose distribution have been measured also with intensity modulated radiation therapy (IMRT), stereotactic radiosurgery (SRS), and volumetric modulated arc therapy (VMAT) patient plans. Comparison has been done with a commercial diode array and with Gafchromic EBT3 films. Repeatability and stability under continuous gamma irradiation are within 0.3%, in spite of low active volume and sensitivity (∼200 pC/Gy). Deviation from linearity is in the range [0.3%, -0.9%] for a dose of at least 20 cGy, while a worsening of linearity is observed below 10 cGy. Charge collection efficiency with 2.67 mGy/pulse is higher than 99%, leading to a ±0.9% sensitivity change in the range 0.09-2.67 mGy/pulse (covering all flattened and unflattened beam qualities). Tissue to phantom ratios show an agreement within 0.6% with the reference detector up to 34 cm depth. For field sizes in the range 2 × 2 to 15 × 15 cm(2), the output factors are in agreement with a thimble chamber within 2%, while with 25 × 25 cm(2) field size, an underestimation of 4.0% was found. Agreement of field and penumbra width measurements with the flat panel is of the order of 1 mm down to 1 × 1 cm(2) field size. Flatness and symmetry values measured with the 1D array and the reference detectors are comparable, and differences are always smaller than 1%. Angular dependence of the detector, when compared to measurements taken with a cylindrical chamber in the same phantom, is as large as 16%. This includes inhomogeneity and asymmetry of the design, which during plan verification are accounted for by the treatment planning system (TPS). The detector is capable to reproduce the dose distributions of IMRT and VMAT plans with a maximum deviation from TPS of 3.0% in the target region. In the case of VMAT and SRS plans, an average (maximum) deviation of the order of 1% (4%) from films has been measured. The investigated technology appears to be useful both for Linac QA and patient plan verification, especially in treatments with steep dose gradients and nonuniform dose rates such as VMAT and SRS. Major limitations of the present prototype are the linearity at low dose, which can be solved by optimizing the readout electronics, and the underestimation of output factors with large field sizes. The latter problem is presently not completely understood and will require further investigations.

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

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

3D track reconstruction capability of a silicon hybrid active pixel detector

NASA Astrophysics Data System (ADS)

Bergmann, Benedikt; Pichotka, Martin; Pospisil, Stanislav; Vycpalek, Jiri; Burian, Petr; Broulim, Pavel; Jakubek, Jan

2017-06-01

Timepix3 detectors are the latest generation of hybrid active pixel detectors of the Medipix/Timepix family. Such detectors consist of an active sensor layer which is connected to the readout ASIC (application specific integrated circuit), segmenting the detector into a square matrix of 256 × 256 pixels (pixel pitch 55 μm). Particles interacting in the active sensor material create charge carriers, which drift towards the pixelated electrode, where they are collected. In each pixel, the time of the interaction (time resolution 1.56 ns) and the amount of created charge carriers are measured. Such a device was employed in an experiment in a 120 GeV/c pion beam. It is demonstrated, how the drift time information can be used for "4D" particle tracking, with the three spatial dimensions and the energy losses along the particle trajectory (dE/dx). Since the coordinates in the detector plane are given by the pixelation ( x, y), the x- and y-resolution is determined by the pixel pitch (55 μm). A z-resolution of 50.4 μm could be achieved (for a 500 μm thick silicon sensor at 130 V bias), whereby the drift time model independent z-resolution was found to be 28.5 μm.

Accuracy of measurement of star images on a pixel array

NASA Technical Reports Server (NTRS)

King, I. R.

1983-01-01

Algorithms are developed for predicting the accuracy with which the brightness of a star can be determined from its image on a digital detector array, as a function of the brightness of the background. The assumption is made that a known profile is being fitted by least squares. The two profiles used correspond to ST images and to ground-based observations. The first result is an approximate rule of thumb for equivalent noise area. More rigorous results are then given in tabular form. The size of the pixels, relative to the image size, is taken into account. Astronometric accuracy is also discussed briefly; the error, relative to image size, is very similar to the photometric error relative to brightness.

Solar-blind ultraviolet optical system design for missile warning

NASA Astrophysics Data System (ADS)

Chen, Yu; Huo, Furong; Zheng, Liqin

2015-03-01

Solar-blind region of Ultraviolet (UV) spectrum has very important application in military field. The spectrum range is from 240nm to 280nm, which can be applied to detect the tail flame from approaching missile. A solar-blind UV optical system is designed to detect the UV radiation, which is an energy system. iKon-L 936 from ANDOR company is selected as the UV detector, which has pixel size 13.5μm x 13.5 μm and active image area 27.6mm x 27.6 mm. CaF2 and F_silica are the chosen materials. The original structure is composed of 6 elements. To reduce the system structure and improve image quality, two aspheric surfaces and one diffractive optical element are adopted in this paper. After optimization and normalization, the designed system is composed of five elements with the maximum spot size 11.988μ m, which is less than the pixel size of the selected CCD detector. Application of aspheric surface and diffractive optical element makes each FOV have similar spot size, which shows the system almost meets the requirements of isoplanatic condition. If the focal length can be decreased, the FOV of the system can be enlarged further.

Terahertz imaging with compressive sensing

NASA Astrophysics Data System (ADS)

Chan, Wai Lam

Most existing terahertz imaging systems are generally limited by slow image acquisition due to mechanical raster scanning. Other systems using focal plane detector arrays can acquire images in real time, but are either too costly or limited by low sensitivity in the terahertz frequency range. To design faster and more cost-effective terahertz imaging systems, the first part of this thesis proposes two new terahertz imaging schemes based on compressive sensing (CS). Both schemes can acquire amplitude and phase-contrast images efficiently with a single-pixel detector, thanks to the powerful CS algorithms which enable the reconstruction of N-by- N pixel images with much fewer than N2 measurements. The first CS Fourier imaging approach successfully reconstructs a 64x64 image of an object with pixel size 1.4 mm using a randomly chosen subset of the 4096 pixels which defines the image in the Fourier plane. Only about 12% of the pixels are required for reassembling the image of a selected object, equivalent to a 2/3 reduction in acquisition time. The second approach is single-pixel CS imaging, which uses a series of random masks for acquisition. Besides speeding up acquisition with a reduced number of measurements, the single-pixel system can further cut down acquisition time by electrical or optical spatial modulation of random patterns. In order to switch between random patterns at high speed in the single-pixel imaging system, the second part of this thesis implements a multi-pixel electrical spatial modulator for terahertz beams using active terahertz metamaterials. The first generation of this device consists of a 4x4 pixel array, where each pixel is an array of sub-wavelength-sized split-ring resonator elements fabricated on a semiconductor substrate, and is independently controlled by applying an external voltage. The spatial modulator has a uniform modulation depth of around 40 percent across all pixels, and negligible crosstalk, at the resonant frequency. The second-generation spatial terahertz modulator, also based on metamaterials with a higher resolution (32x32), is under development. A FPGA-based circuit is designed to control the large number of modulator pixels. Once fully implemented, this second-generation device will enable fast terahertz imaging with both pulsed and continuous-wave terahertz sources.

Direct reading of charge multipliers with a self-triggering CMOS analog chip with 105 k pixels at 50 μm pitch

NASA Astrophysics Data System (ADS)

Bellazzini, R.; Spandre, G.; Minuti, M.; Baldini, L.; Brez, A.; Cavalca, F.; Latronico, L.; Omodei, N.; Massai, M. M.; Sgro', C.; Costa, E.; Soffitta, P.; Krummenacher, F.; de Oliveira, R.

2006-10-01

We report on a large area (15×15 mm2), high channel density (470 pixel/mm2), self-triggering CMOS analog chip that we have developed as a pixelized charge collecting electrode of a Micropattern Gas Detector. This device represents a big step forward both in terms of size and performance, and is in fact the last version of three generations of custom ASICs of increasing complexity. The top metal layer of the CMOS pixel array is patterned in a matrix of 105,600 hexagonal pixels with a 50 μm pitch. Each pixel is directly connected to the underlying full electronics chain which has been realized in the remaining five metal and single poly-silicon layers of a 0.18 μm VLSI technology. The chip, which has customizable self-triggering capabilities, also includes a signal pre-processing function for the automatic localization of the event coordinates. Thanks to these advances it is possible to significantly reduce the read-out time and the data volume by limiting the signal output only to those pixels belonging to the region of interest. In addition to the reduced read-out time and data volume, the very small pixel area and the use of a deep sub-micron CMOS technology has allowed bringing the noise down to 50 electrons ENC. Results from in depth tests of this device when coupled to a fine pitch (50 μm on a triangular pattern) Gas Electron Multiplier are presented. It was found that matching the read-out and gas amplification pitch allows getting optimal results. The experimental detector response to polarized and unpolarized X-ray radiation when working with two gas mixtures and two different photon energies is shown and the application of this detector for Astronomical X-ray Polarimetry is discussed. Results from a full Monte-Carlo simulation for several galactic and extragalactic astronomical sources are also reported.

Pixelated transmission-mode diamond X-ray detector.

PubMed

Zhou, Tianyi; Ding, Wenxiang; Gaowei, Mengjia; De Geronimo, Gianluigi; Bohon, Jen; Smedley, John; Muller, Erik

2015-11-01

Fabrication and testing of a prototype transmission-mode pixelated diamond X-ray detector (pitch size 60-100 µm), designed to simultaneously measure the flux, position and morphology of an X-ray beam in real time, are described. The pixel density is achieved by lithographically patterning vertical stripes on the front and horizontal stripes on the back of an electronic-grade chemical vapor deposition single-crystal diamond. The bias is rotated through the back horizontal stripes and the current is read out on the front vertical stripes at a rate of ∼ 1 kHz, which leads to an image sampling rate of ∼ 30 Hz. This novel signal readout scheme was tested at beamline X28C at the National Synchrotron Light Source (white beam, 5-15 keV) and at beamline G3 at the Cornell High Energy Synchrotron Source (monochromatic beam, 11.3 keV) with incident beam flux ranges from 1.8 × 10(-2) to 90 W mm(-2). Test results show that the novel detector provides precise beam position (positional noise within 1%) and morphology information (error within 2%), with an additional software-controlled single channel mode providing accurate flux measurement (fluctuation within 1%).

On the performance of large monolithic LaCl3(Ce) crystals coupled to pixelated silicon photosensors

NASA Astrophysics Data System (ADS)

Olleros, P.; Caballero, L.; Domingo-Pardo, C.; Babiano, V.; Ladarescu, I.; Calvo, D.; Gramage, P.; Nacher, E.; Tain, J. L.; Tolosa, A.

2018-03-01

We investigate the performance of large area radiation detectors, with high energy- and spatial-resolution, intended for the development of a Total Energy Detector with gamma-ray imaging capability, so-called i-TED. This new development aims for an enhancement in detection sensitivity in time-of-flight neutron capture measurements, versus the commonly used C6D6 liquid scintillation total-energy detectors. In this work, we study in detail the impact of the readout photosensor on the energy response of large area (50×50 mm2) monolithic LaCl3(Ce) crystals, in particular when replacing a conventional mono-cathode photomultiplier tube by an 8×8 pixelated silicon photomultiplier. Using the largest commercially available monolithic SiPM array (25 cm2), with a pixel size of 6×6 mm2, we have measured an average energy resolution of 3.92% FWHM at 662 keV for crystal thicknesses of 10, 20 and 30 mm. The results are confronted with detailed Monte Carlo (MC) calculations, where optical processes and properties have been included for the reliable tracking of the scintillation photons. After the experimental validation of the MC model, we use our MC code to explore the impact of a smaller photosensor segmentation on the energy resolution. Our optical MC simulations predict only a marginal deterioration of the spectroscopic performance for pixels of 3×3 mm2.

Development of high energy micro-tomography system at SPring-8

NASA Astrophysics Data System (ADS)

Uesugi, Kentaro; Hoshino, Masato

2017-09-01

A high energy X-ray micro-tomography system has been developed at BL20B2 in SPring-8. The available range of the energy is between 20keV and 113keV with a Si (511) double crystal monochromator. The system enables us to image large or heavy materials such as fossils and metals. The X-ray image detector consists of visible light conversion system and sCMOS camera. The effective pixel size is variable by changing a tandem lens between 6.5 μm/pixel and 25.5 μm/pixel discretely. The format of the camera is 2048 pixels x 2048 pixels. As a demonstration of the system, alkaline battery and a nodule from Bolivia were imaged. A detail of the structure of the battery and a female mold Trilobite were successfully imaged without breaking those fossils.

14C autoradiography with an energy-sensitive silicon pixel detector.

PubMed

Esposito, M; Mettivier, G; Russo, P

2011-04-07

The first performance tests are presented of a carbon-14 ((14)C) beta-particle digital autoradiography system with an energy-sensitive hybrid silicon pixel detector based on the Timepix readout circuit. Timepix was developed by the Medipix2 Collaboration and it is similar to the photon-counting Medipix2 circuit, except for an added time-based synchronization logic which allows derivation of energy information from the time-over-threshold signal. This feature permits direct energy measurements in each pixel of the detector array. Timepix is bump-bonded to a 300 µm thick silicon detector with 256 × 256 pixels of 55 µm pitch. Since an energetic beta-particle could release its kinetic energy in more than one detector pixel as it slows down in the semiconductor detector, an off-line image analysis procedure was adopted in which the single-particle cluster of hit pixels is recognized; its total energy is calculated and the position of interaction on the detector surface is attributed to the centre of the charge cluster. Measurements reported are detector sensitivity, (4.11 ± 0.03) × 10(-3) cps mm(-2) kBq(-1) g, background level, (3.59 ± 0.01) × 10(-5) cps mm(-2), and minimum detectable activity, 0.0077 Bq. The spatial resolution is 76.9 µm full-width at half-maximum. These figures are compared with several digital imaging detectors for (14)C beta-particle digital autoradiography.

Evaluation of PET Imaging Resolution Using 350 mu{m} Pixelated CZT as a VP-PET Insert Detector

NASA Astrophysics Data System (ADS)

Yin, Yongzhi; Chen, Ximeng; Li, Chongzheng; Wu, Heyu; Komarov, Sergey; Guo, Qingzhen; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2014-02-01

A cadmium-zinc-telluride (CZT) detector with 350 μm pitch pixels was studied in high-resolution positron emission tomography (PET) imaging applications. The PET imaging system was based on coincidence detection between a CZT detector and a lutetium oxyorthosilicate (LSO)-based Inveon PET detector in virtual-pinhole PET geometry. The LSO detector is a 20 ×20 array, with 1.6 mm pitches, and 10 mm thickness. The CZT detector uses ac 20 ×20 ×5 mm substrate, with 350 μm pitch pixelated anodes and a coplanar cathode. A NEMA NU4 Na-22 point source of 250 μm in diameter was imaged by this system. Experiments show that the image resolution of single-pixel photopeak events was 590 μm FWHM while the image resolution of double-pixel photopeak events was 640 μm FWHM. The inclusion of double-pixel full-energy events increased the sensitivity of the imaging system. To validate the imaging experiment, we conducted a Monte Carlo (MC) simulation for the same PET system in Geant4 Application for Emission Tomography. We defined LSO detectors as a scanner ring and 350 μm pixelated CZT detectors as an insert ring. GATE simulated coincidence data were sorted into an insert-scanner sinogram and reconstructed. The image resolution of MC-simulated data (which did not factor in positron range and acolinearity effect) was 460 μm at FWHM for single-pixel events. The image resolutions of experimental data, MC simulated data, and theoretical calculation are all close to 500 μm FWHM when the proposed 350 μm pixelated CZT detector is used as a PET insert. The interpolation algorithm for the charge sharing events was also investigated. The PET image that was reconstructed using the interpolation algorithm shows improved image resolution compared with the image resolution without interpolation algorithm.

ePix: a class of architectures for second generation LCLS cameras

DOE PAGES

Dragone, A.; Caragiulo, P.; Markovic, B.; ...

2014-03-31

ePix is a novel class of ASIC architectures, based on a common platform, optimized to build modular scalable detectors for LCLS. The platform architecture is composed of a random access analog matrix of pixel with global shutter, fast parallel column readout, and dedicated sigma-delta analog-to-digital converters per column. It also implements a dedicated control interface and all the required support electronics to perform configuration, calibration and readout of the matrix. Based on this platform a class of front-end ASICs and several camera modules, meeting different requirements, can be developed by designing specific pixel architectures. This approach reduces development time andmore » expands the possibility of integration of detector modules with different size, shape or functionality in the same camera. The ePix platform is currently under development together with the first two integrating pixel architectures: ePix100 dedicated to ultra low noise applications and ePix10k for high dynamic range applications.« less

Study of run time errors of the ATLAS pixel detector in the 2012 data taking period

NASA Astrophysics Data System (ADS)

Gandrajula, Reddy Pratap

The high resolution silicon Pixel detector is critical in event vertex reconstruction and in particle track reconstruction in the ATLAS detector. During the pixel data taking operation, some modules (Silicon Pixel sensor +Front End Chip+ Module Control Chip (MCC)) go to an auto-disable state, where the Modules don't send the data for storage. Modules become operational again after reconfiguration. The source of the problem is not fully understood. One possible source of the problem is traced to the occurrence of single event upset (SEU) in the MCC. Such a module goes to either a Timeout or Busy state. This report is the study of different types and rates of errors occurring in the Pixel data taking operation. Also, the study includes the error rate dependency on Pixel detector geometry.

Mercuric iodide medical imagers for low-exposure radiography and fluoroscopy

NASA Astrophysics Data System (ADS)

Zentai, George; Partain, Larry; Pavlyuchkova, Raisa; Proano, Cesar; Breen, Barry N.; Taieb, A.; Dagan, Ofer; Schieber, Michael; Gilboa, Haim; Thomas, Jerry

2004-05-01

Photoconductive polycrystalline mercuric iodide deposited on flat panel thin film transistor (TFT) arrays is being developed for direct digital X-ray detectors that can perform both radiographic and fluoroscopic medical imaging. The mercuric iodide is either vacuum deposited by Physical Vapor Deposition (PVD) or coated onto the array by a wet Particle-In-Binder (PIB) process. The PVD deposition technology has been scaled up to the 20 cm x 25 cm size required in common medical imaging applications. A TFT array with a pixel pitch of 127 microns is used for these imagers. Arrays of 10 cm x 10 cm size have been used to evaluate performance of mercuric iodide imagers. Radiographic and fluoroscopic images of diagnostic quality at up to 15 pulses per second were demonstrated. As we previously reported, the resolution is limited to the TFT array Nyquist frequency of ~3.9 lp/mm (127 micron pixel pitch). Detective Quantum Efficiency (DQE) has been measured as a function of spatial frequency for these imagers. The DQE is lower than the theoretically calculated value due to some additional noise sources of the electronics and the array. We will retest the DQE after eliminating these noise sources. Reliability and stress testing was also began for polycrystalline mercuric iodide PVD and PIB detectors. These are simplified detectors based upon a stripe electrode or circular electrode structure. The detectors were stressed under various voltage bias, temperature and time conditions. The effects of the stress tests on the detector dark current and sensitivity were determined.

Characterizing X-ray detectors for prototype digital breast tomosynthesis systems

NASA Astrophysics Data System (ADS)

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 detectors for commercial DBT systems. Our findings suggest that the Dexela detector can be applied to the DBT system with regard to its high imaging performance.

An inverter-based capacitive trans-impedance amplifier readout with offset cancellation and temporal noise reduction for IR focal plane array

NASA Astrophysics Data System (ADS)

Chen, Hsin-Han; Hsieh, Chih-Cheng

2013-09-01

This paper presents a readout integrated circuit (ROIC) with inverter-based capacitive trans-impedance amplifier (CTIA) and pseudo-multiple sampling technique for infrared focal plane array (IRFPA). The proposed inverter-based CTIA with a coupling capacitor [1], executing auto-zeroing technique to cancel out the varied offset voltage from process variation, is used to substitute differential amplifier in conventional CTIA. The tunable detector bias is applied from a global external bias before exposure. This scheme not only retains stable detector bias voltage and signal injection efficiency, but also reduces the pixel area as well. Pseudo-multiple sampling technique [2] is adopted to reduce the temporal noise of readout circuit. The noise reduction performance is comparable to the conventional multiple sampling operation without need of longer readout time proportional to the number of samples. A CMOS image sensor chip with 55×65 pixel array has been fabricated in 0.18um CMOS technology. It achieves a 12um×12um pixel size, a frame rate of 72 fps, a power-per-pixel of 0.66uW/pixel, and a readout temporal noise of 1.06mVrms (16 times of pseudo-multiple sampling), respectively.

Pixel Stability in the Hubble Space Telescope WFC3/UVIS Detector

NASA Astrophysics Data System (ADS)

Bourque, Matthew; Baggett, Sylvia M.; Borncamp, David; Desjardins, Tyler D.; Grogin, Norman A.; Wide Field Camera 3 Team

2018-06-01

The Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) Ultraviolet-Visible (UVIS) detector has acquired roughly 12,000 dark images since the installation of WFC3 in 2009, as part of a daily monitoring program to measure the instrinsic dark current of the detector. These images have been reconfigured into 'pixel history' images in which detector columns are extracted from each dark and placed into a new time-ordered array, allowing for efficient analysis of a given pixel's behavior over time. We discuss how we measure each pixel's stability, as well as plans for a new Data Quality (DQ) flag to be introduced in a future release of the WFC3 calibration pipeline (CALWF3) for flagging pixels that are deemed unstable.

Evaluation of a hybrid pixel detector for electron microscopy.

PubMed

Faruqi, A R; Cattermole, D M; Henderson, R; Mikulec, B; Raeburn, C

2003-04-01

We describe the application of a silicon hybrid pixel detector, containing 64 by 64 pixels, each 170 microm(2), in electron microscopy. The device offers improved resolution compared to CCDs along with faster and noiseless readout. Evaluation of the detector, carried out on a 120 kV electron microscope, demonstrates the potential of the device.

A novel pixellated solid-state photon detector for enhancing the Everhart-Thornley detector.

PubMed

Chuah, Joon Huang; Holburn, David

2013-06-01

This article presents a pixellated solid-state photon detector designed specifically to improve certain aspects of the existing Everhart-Thornley detector. The photon detector was constructed and fabricated in an Austriamicrosystems 0.35 µm complementary metal-oxide-semiconductor process technology. This integrated circuit consists of an array of high-responsivity photodiodes coupled to corresponding low-noise transimpedance amplifiers, a selector-combiner circuit and a variable-gain postamplifier. Simulated and experimental results show that the photon detector can achieve a maximum transimpedance gain of 170 dBΩ and minimum bandwidth of 3.6 MHz. It is able to detect signals with optical power as low as 10 nW and produces a minimum signal-to-noise ratio (SNR) of 24 dB regardless of gain configuration. The detector has been proven to be able to effectively select and combine signals from different pixels. The key advantages of this detector are smaller dimensions, higher cost effectiveness, lower voltage and power requirements and better integration. The photon detector supports pixel-selection configurability which may improve overall SNR and also potentially generate images for different analyses. This work has contributed to the future research of system-level integration of a pixellated solid-state detector for secondary electron detection in the scanning electron microscope. Copyright © 2013 Wiley Periodicals, Inc.

Chromatic Modulator for a High-Resolution CCD or APS

NASA Technical Reports Server (NTRS)

Hartley, Frank; Hull, Anthony

2008-01-01

A chromatic modulator has been proposed to enable the separate detection of the red, green, and blue (RGB) color components of the same scene by a single charge-coupled device (CCD), active-pixel sensor (APS), or similar electronic image detector. Traditionally, the RGB color-separation problem in an electronic camera has been solved by use of either (1) fixed color filters over three separate image detectors; (2) a filter wheel that repeatedly imposes a red, then a green, then a blue filter over a single image detector; or (3) different fixed color filters over adjacent pixels. The use of separate image detectors necessitates precise registration of the detectors and the use of complicated optics; filter wheels are expensive and add considerably to the bulk of the camera; and fixed pixelated color filters reduce spatial resolution and introduce color-aliasing effects. The proposed chromatic modulator would not exhibit any of these shortcomings. The proposed chromatic modulator would be an electromechanical device fabricated by micromachining. It would include a filter having a spatially periodic pattern of RGB strips at a pitch equal to that of the pixels of the image detector. The filter would be placed in front of the image detector, supported at its periphery by a spring suspension and electrostatic comb drive. The spring suspension would bias the filter toward a middle position in which each filter strip would be registered with a row of pixels of the image detector. Hard stops would limit the excursion of the spring suspension to precisely one pixel row above and one pixel row below the middle position. In operation, the electrostatic comb drive would be actuated to repeatedly snap the filter to the upper extreme, middle, and lower extreme positions. This action would repeatedly place a succession of the differently colored filter strips in front of each pixel of the image detector. To simplify the processing, it would be desirable to encode information on the color of the filter strip over each row (or at least over some representative rows) of pixels at a given instant of time in synchronism with the pixel output at that instant.

A focal plane metrology system and PSF centroiding experiment

NASA Astrophysics Data System (ADS)

Li, Haitao; Li, Baoquan; Cao, Yang; Li, Ligang

2016-10-01

In this paper, we present an overview of a detector array equipment metrology testbed and a micro-pixel centroiding experiment currently under development at the National Space Science Center, Chinese Academy of Sciences. We discuss on-going development efforts aimed at calibrating the intra-/inter-pixel quantum efficiency and pixel positions for scientific grade CMOS detector, and review significant progress in achieving higher precision differential centroiding for pseudo star images in large area back-illuminated CMOS detector. Without calibration of pixel positions and intrapixel response, we have demonstrated that the standard deviation of differential centroiding is below 2.0e-3 pixels.

Evaluation of cassette-based digital radiography detectors using standardized image quality metrics: AAPM TG-150 Draft Image Detector Tests.

PubMed

Li, Guang; Greene, Travis C; Nishino, Thomas K; Willis, Charles E

2016-09-08

The purpose of this study was to evaluate several of the standardized image quality metrics proposed by the American Association of Physics in Medicine (AAPM) Task Group 150. The task group suggested region-of-interest (ROI)-based techniques to measure nonuniformity, minimum signal-to-noise ratio (SNR), number of anomalous pixels, and modulation transfer function (MTF). This study evaluated the effects of ROI size and layout on the image metrics by using four different ROI sets, assessed result uncertainty by repeating measurements, and compared results with two commercially available quality control tools, namely the Carestream DIRECTVIEW Total Quality Tool (TQT) and the GE Healthcare Quality Assurance Process (QAP). Seven Carestream DRX-1C (CsI) detectors on mobile DR systems and four GE FlashPad detectors in radiographic rooms were tested. Images were analyzed using MATLAB software that had been previously validated and reported. Our values for signal and SNR nonuniformity and MTF agree with values published by other investigators. Our results show that ROI size affects nonuniformity and minimum SNR measurements, but not detection of anomalous pixels. Exposure geometry affects all tested image metrics except for the MTF. TG-150 metrics in general agree with the TQT, but agree with the QAP only for local and global signal nonuniformity. The difference in SNR nonuniformity and MTF values between the TG-150 and QAP may be explained by differences in the calculation of noise and acquisition beam quality, respectively. TG-150's SNR nonuniformity metrics are also more sensitive to detector nonuniformity compared to the QAP. Our results suggest that fixed ROI size should be used for consistency because nonuniformity metrics depend on ROI size. Ideally, detector tests should be performed at the exact calibration position. If not feasible, a baseline should be established from the mean of several repeated measurements. Our study indicates that the TG-150 tests can be used as an independent standardized procedure for detector performance assessment. © 2016 The Authors.

Evaluation of cassette‐based digital radiography detectors using standardized image quality metrics: AAPM TG‐150 Draft Image Detector Tests

PubMed Central

Greene, Travis C.; Nishino, Thomas K.; Willis, Charles E.

2016-01-01

The purpose of this study was to evaluate several of the standardized image quality metrics proposed by the American Association of Physics in Medicine (AAPM) Task Group 150. The task group suggested region‐of‐interest (ROI)‐based techniques to measure nonuniformity, minimum signal‐to‐noise ratio (SNR), number of anomalous pixels, and modulation transfer function (MTF). This study evaluated the effects of ROI size and layout on the image metrics by using four different ROI sets, assessed result uncertainty by repeating measurements, and compared results with two commercially available quality control tools, namely the Carestream DIRECTVIEW Total Quality Tool (TQT) and the GE Healthcare Quality Assurance Process (QAP). Seven Carestream DRX‐1C (CsI) detectors on mobile DR systems and four GE FlashPad detectors in radiographic rooms were tested. Images were analyzed using MATLAB software that had been previously validated and reported. Our values for signal and SNR nonuniformity and MTF agree with values published by other investigators. Our results show that ROI size affects nonuniformity and minimum SNR measurements, but not detection of anomalous pixels. Exposure geometry affects all tested image metrics except for the MTF. TG‐150 metrics in general agree with the TQT, but agree with the QAP only for local and global signal nonuniformity. The difference in SNR nonuniformity and MTF values between the TG‐150 and QAP may be explained by differences in the calculation of noise and acquisition beam quality, respectively. TG‐150's SNR nonuniformity metrics are also more sensitive to detector nonuniformity compared to the QAP. Our results suggest that fixed ROI size should be used for consistency because nonuniformity metrics depend on ROI size. Ideally, detector tests should be performed at the exact calibration position. If not feasible, a baseline should be established from the mean of several repeated measurements. Our study indicates that the TG‐150 tests can be used as an independent standardized procedure for detector performance assessment. PACS number(s): 87.57.‐s, 87.57.C PMID:27685102

Locality-constrained anomaly detection for hyperspectral imagery

NASA Astrophysics Data System (ADS)

Liu, Jiabin; Li, Wei; Du, Qian; Liu, Kui

2015-12-01

Detecting a target with low-occurrence-probability from unknown background in a hyperspectral image, namely anomaly detection, is of practical significance. Reed-Xiaoli (RX) algorithm is considered as a classic anomaly detector, which calculates the Mahalanobis distance between local background and the pixel under test. Local RX, as an adaptive RX detector, employs a dual-window strategy to consider pixels within the frame between inner and outer windows as local background. However, the detector is sensitive if such a local region contains anomalous pixels (i.e., outliers). In this paper, a locality-constrained anomaly detector is proposed to remove outliers in the local background region before employing the RX algorithm. Specifically, a local linear representation is designed to exploit the internal relationship between linearly correlated pixels in the local background region and the pixel under test and its neighbors. Experimental results demonstrate that the proposed detector improves the original local RX algorithm.

Detection of X-ray spectra and images by Timepix

NASA Astrophysics Data System (ADS)

Urban, M.; Nentvich, O.; Stehlikova, V.; Sieger, L.

2017-07-01

X-ray monitoring for astrophysical applications mainly consists of two parts - optics and detector. The article describes an approach based on a combination of Lobster Eye (LE) optics with Timepix detector. Timepix is a semiconductor detector with 256 × 256 pixels on one electrode and a second electrode is common. Usage of the back-side-pulse from an common electrode of pixelated detector brings the possibility of an additional spectroscopic or trigger signal. In this article are described effects of the thermal stabilisation, and the cooling effect of the detector working as single pixel.

Readout and DAQ for Pixel Detectors

NASA Astrophysics Data System (ADS)

Platkevic, Michal

2010-01-01

Data readout and acquisition control of pixel detectors demand the transfer of significantly a large amounts of bits between the detector and the computer. For this purpose dedicated interfaces are used which are designed with focus on features like speed, small dimensions or flexibility of use such as digital signal processors, field-programmable gate arrays (FPGA) and USB communication ports. This work summarizes the readout and DAQ system built for state-of-the-art pixel detectors of the Medipix family.

Forward model with space-variant of source size for reconstruction on X-ray radiographic image

NASA Astrophysics Data System (ADS)

Liu, Jin; Liu, Jun; Jing, Yue-feng; Xiao, Bo; Wei, Cai-hua; Guan, Yong-hong; Zhang, Xuan

2018-03-01

The Forward Imaging Technique is a method to solve the inverse problem of density reconstruction in radiographic imaging. In this paper, we introduce the forward projection equation (IFP model) for the radiographic system with areal source blur and detector blur. Our forward projection equation, based on X-ray tracing, is combined with the Constrained Conjugate Gradient method to form a new method for density reconstruction. We demonstrate the effectiveness of the new technique by reconstructing density distributions from simulated and experimental images. We show that for radiographic systems with source sizes larger than the pixel size, the effect of blur on the density reconstruction is reduced through our method and can be controlled within one or two pixels. The method is also suitable for reconstruction of non-homogeneousobjects.

Reduced-Scale Transition-Edge Sensor Detectors for Solar and X-Ray Astrophysics

NASA Technical Reports Server (NTRS)

Datesman, Aaron M.; Adams, Joseph S.; Bandler, Simon R.; Betancourt-Martinez, Gabriele L.; Chang, Meng-Ping; Chervenak, James A.; Eckart, Megan E.; Ewin, Audrey E.; Finkbeiner, Fred M.; Ha, Jong Yoon;

Comparison of high resolution x-ray detectors with conventional FPDs using experimental MTFs and apodized aperture pixel design for reduced aliasing

NASA Astrophysics Data System (ADS)

Shankar, A.; Russ, M.; Vijayan, S.; Bednarek, D. R.; Rudin, S.

2017-03-01

Apodized Aperture Pixel (AAP) design, proposed by Ismailova et.al, is an alternative to the conventional pixel design. The advantages of AAP processing with a sinc filter in comparison with using other filters include non-degradation of MTF values and elimination of signal and noise aliasing, resulting in an increased performance at higher frequencies, approaching the Nyquist frequency. If high resolution small field-of-view (FOV) detectors with small pixels used during critical stages of Endovascular Image Guided Interventions (EIGIs) could also be extended to cover a full field-of-view typical of flat panel detectors (FPDs) and made to have larger effective pixels, then methods must be used to preserve the MTF over the frequency range up to the Nyquist frequency of the FPD while minimizing aliasing. In this work, we convolve the experimentally measured MTFs of an Microangiographic Fluoroscope (MAF) detector, (the MAF-CCD with 35μm pixels) and a High Resolution Fluoroscope (HRF) detector (HRF-CMOS50 with 49.5μm pixels) with the AAP filter and show the superiority of the results compared to MTFs resulting from moving average pixel binning and to the MTF of a standard FPD. The effect of using AAP is also shown in the spatial domain, when used to image an infinitely small point object. For detectors in neurovascular interventions, where high resolution is the priority during critical parts of the intervention, but full FOV with larger pixels are needed during less critical parts, AAP design provides an alternative to simple pixel binning while effectively eliminating signal and noise aliasing yet allowing the small FOV high resolution imaging to be maintained during critical parts of the EIGI.

Performance comparison of small-pixel CdZnTe radiation detectors with gold contacts formed by sputter and electroless deposition

NASA Astrophysics Data System (ADS)

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

2017-06-01

Recent improvements in the growth of wide-bandgap semiconductors, such as cadmium zinc telluride (CdZnTe or CZT), has enabled spectroscopic X/γ-ray imaging detectors to be developed. These detectors have applications covering homeland security, industrial analysis, space science and medical imaging. At the Rutherford Appleton Laboratory (RAL) a promising range of spectroscopic, position sensitive, small-pixel Cd(Zn)Te detectors have been developed. The challenge now is to improve the quality of metal contacts on CdZnTe in order to meet the demanding energy and spatial resolution requirements of these applications. The choice of metal deposition method and fabrication process are of fundamental importance. Presented is a comparison of two CdZnTe detectors with contacts formed by sputter and electroless deposition. The detectors were fabricated with a 74 × 74 array of 200 μm pixels on a 250 μm pitch and bump-bonded to the HEXITEC ASIC. The X/γ-ray emissions from an 241Am source were measured to form energy spectra for comparison. It was found that the detector with contacts formed by electroless deposition produced the best uniformity and energy resolution; the best pixel produced a FWHM of 560 eV at 59.54 keV and 50% of pixels produced a FWHM better than 1.7 keV . This compared with a FWHM of 1.5 keV for the best pixel and 50% of pixels better than 4.4 keV for the detector with sputtered contacts.

Measurements and simulations of MAPS (Monolithic Active Pixel Sensors) response to charged particles - a study towards a vertex detector at the ILC

NASA Astrophysics Data System (ADS)

Maczewski, Lukasz

2010-05-01

The International Linear Collider (ILC) is a project of an electron-positron (e+e-) linear collider with the centre-of-mass energy of 200-500 GeV. Monolithic Active Pixel Sensors (MAPS) are one of the proposed silicon pixel detector concepts for the ILC vertex detector (VTX). Basic characteristics of two MAPS pixel matrices MIMOSA-5 (17 μm pixel pitch) and MIMOSA-18 (10 μm pixel pitch) are studied and compared (pedestals, noises, calibration of the ADC-to-electron conversion gain, detector efficiency and charge collection properties). The e+e- collisions at the ILC will be accompanied by intense beamsstrahlung background of electrons and positrons hitting inner planes of the vertex detector. Tracks of this origin leave elongated clusters contrary to those of secondary hadrons. Cluster characteristics and orientation with respect to the pixels netting are studied for perpendicular and inclined tracks. Elongation and precision of determining the cluster orientation as a function of the angle of incidence were measured. A simple model of signal formation (based on charge diffusion) is proposed and tested using the collected data.

Experimental realization of a metamaterial detector focal plane array.

PubMed

Shrekenhamer, David; Xu, Wangren; Venkatesh, Suresh; Schurig, David; Sonkusale, Sameer; Padilla, Willie J

2012-10-26

We present a metamaterial absorber detector array that enables room-temperature, narrow-band detection of gigahertz (GHz) radiation in the S band (2-4 GHz). The system is implemented in a commercial printed circuit board process and we characterize the detector sensitivity and angular dependence. A modified metamaterial absorber geometry allows for each unit cell to act as an isolated detector pixel and to collectively form a focal plane array . Each pixel can have a dedicated microwave receiver chain and functions together as a hybrid device tuned to maximize the efficiency of detected power. The demonstrated subwavelength pixel shows detected sensitivity of -77 dBm, corresponding to a radiation power density of 27 nW/m(2), with pixel to pixel coupling interference below -14 dB at 2.5 GHz.

The Speedster-EXD- A New Event-Driven Hybrid CMOS X-ray Detector

NASA Astrophysics Data System (ADS)

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.

A New Camera for Powder Diffraction of Macromolecular Crystallography at SPring-8

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miura, Keiko; Inoue, Katsuaki; Goto, Shunji

2004-05-12

A powder diffractometer of Guinier geometry was developed and tested on a beamline, BL40B2, at SPring-8. The long specimen-to-detector distance, 1,000 mm, is advantageous in recording diffraction from Bragg spacing of 20 nm or larger. The angular resolution, 0.012 degrees, was realized together with the focusing optics, the long specimen-to-detector distance and the small pixel size of Blue-type Imaging Plate detector. Such a high resolution makes the peak separation possible in the powder diffraction from microcrystals with large unit cell and low symmetry of biological macromolecules.

10μm pitch family of InSb and XBn detectors for MWIR imaging

NASA Astrophysics Data System (ADS)

Gershon, G.; Avnon, E.; Brumer, M.; Freiman, W.; Karni, Y.; Niderman, T.; Ofer, O.; Rosenstock, T.; Seref, D.; Shiloah, N.; Shkedy, L.; Tessler, R.; Shtrichman, I.

2017-02-01

There has been a growing demand over the past few years for infrared detectors with a smaller pixel dimension. On the one hand, this trend of pixel shrinkage enables the overall size of a given Focal Plan Array (FPA) to be reduced, allowing the production of more compact, lower power, and lower cost electro-optical (EO) systems. On the other hand, it enables a higher image resolution for a given FPA area, which is especially suitable in infrared systems with a large format that are used with a wide Field of View (FOV). In response to these market trends SCD has developed the Blackbird family of 10 μm pitch MWIR digital infrared detectors. The Blackbird family is based on three different Read- Out Integrated Circuit (ROIC) formats: 1920×1536, 1280×1024 and 640×512, which exploit advanced and mature 0.18 μm CMOS technology and exhibit high functionality with relatively low power consumption. Two types of 10 μm pixel sensing arrays are supported. The first is an InSb photodiode array based on SCD's mature planar implanted p-n junction technology, which covers the full MWIR band, and is designed to operate at 77K. The second type of sensing array covers the blue part of the MWIR band and uses the patented XBn-InAsSb barrier detector technology that provides electro-optical performance equivalent to planar InSb but at operating temperatures as high as 150 K. The XBn detector is therefore ideal for low Size, Weight and Power (SWaP) applications. Both sensing arrays, InSb and XBn, are Flip-chip bonded to the ROICs and assembled into custom designed Dewars that can withstand harsh environmental conditions while minimizing the detector heat load. A dedicated proximity electronics board provides power supplies and timing to the ROIC and enables communication and video output to the system. Together with a wide range of cryogenic coolers, a high flexibility of housing designs and various modes of operation, the Blackbird family of detectors presents solutions for EO systems which cover both the very high-end and the low SWaP types of application. In this work we present in detail the EO performance of the Blackbird detector family.

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

NASA Astrophysics Data System (ADS)

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

2017-06-01

A photon counting detector (PCD) has been proposed as an alternative solution to an energy-integrating detector (EID) in medical imaging field due to its high resolution, high efficiency, and low noise. The PCD has expanded to variety of fields such as spectral CT, k-edge imaging, and material decomposition owing to its capability to count and measure the number and the energy of an incident photon, respectively. Nonetheless, pulse pile-up, which is a superimposition of pulses at the output of a charge sensitive amplifier (CSA) in each PC pixel, occurs frequently as the X-ray flux increases due to the finite pulse processing time (PPT) in CSAs. Pulse pile-up induces not only a count loss but also distortion in the measured X-ray spectrum from each PC pixel and thus it is a main constraint on the use of PCDs in high flux X-ray applications. To minimize these effects, an energy-correction PC (ECPC) pixel is proposed to resolve pulse pile-up without cutting off the PPT by adding an energy correction logic (ECL) via a cross detection method (CDM). The ECPC pixel with a size of 200×200 μm2 was fabricated by using a 6-metal 1-poly 0.18 μm CMOS process with a static power consumption of 7.2 μW/pixel. The maximum count rate of the ECPC pixel was extended by approximately three times higher than that of a conventional PC pixel with a PPT of 500 nsec. The X-ray spectrum of 90 kVp, filtered by 3 mm Al filter, was measured as the X-ray current was increased using the CdTe and the ECPC pixel. As a result, the ECPC pixel dramatically reduced the energy spectrum distortion at 2 Mphotons/pixel/s when compared to that of the ERCP pixel with the same 500 nsec PPT.

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

DOE PAGES

Philipp, Hugh T.; Tate, Mark W.; Purohit, Prafull; ...

2016-01-28

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 atmore » 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. Lastly, we detail the characteristics, operation, testing and application of the detector.« less

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

PubMed Central

Philipp, Hugh T.; Tate, Mark W.; Purohit, Prafull; Shanks, Katherine S.; Weiss, Joel T.; Gruner, Sol M.

2016-01-01

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. PMID:26917125

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

PubMed

Philipp, Hugh T; Tate, Mark W; Purohit, Prafull; Shanks, Katherine S; Weiss, Joel T; Gruner, Sol M

2016-03-01

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.

Integration of the ATLAS FE-I4 Pixel Chip in the Mini Time Projection Chamber

NASA Astrophysics Data System (ADS)

Lopez-Thibodeaux, Mayra; Garcia-Sciveres, Maurice; Kadyk, John; Oliver-Mallory, Kelsey

2013-04-01

This project deals with development of readout for a Time Projection Chamber (TPC) prototype. This is a type of detector proposed for direct detection of dark matter (WIMPS) with direction information. The TPC is a gaseous charged particle tracking detector composed of a field cage and a gas avalanche detector. The latter is made of two Gas Electron Multipliers in series, illuminating a pixel readout integrated circuit, which measures the distribution in position and time of the output charge. We are testing the TPC prototype, filled with ArCO2 gas, using a Fe-55 x-ray source and cosmic rays. The present prototype uses an FE-I3 chip for readout. This chip was developed about 10 years ago and is presently in use within the ATLAS pixel detector at the LHC. The aim of this work is to upgrade the TPC prototype to use an FE-I4 chip. The FE-I4 has an active area of 336 mm^2 and 26880 pixels, over nine times the number of pixels in the FE-I3 chip, and an active area about six times as much. The FE-I4 chip represents the state of the art of pixel detector readout, and is presently being used to build an upgrade of the ATLAS pixel detector.

VizieR Online Data Catalog: New redshifts for Abell 1758N galaxies (Boschin+, 2012)

NASA Astrophysics Data System (ADS)

Boschin, W.; Girardi, M.; Barrena, R.; Nonino, M.

2012-06-01

Multi-object spectroscopic observations of A1758N were carried out at the TNG, a 4m-class telescope, in May 2008 and May 2009. We used DOLORES/MOS with the LR-B Grism 1, yielding a dispersion of 187Å/mm. The detector is a 2048x2048 pixels E2V CCD, with a pixel size of 13.5um. In total, we observed four MOS masks (one in 2008 and three in 2009) for a total of 146 slits. (1 data file).

Velocity map imaging using an in-vacuum pixel detector.

PubMed

Gademann, Georg; Huismans, Ymkje; Gijsbertsen, Arjan; Jungmann, Julia; Visschers, Jan; Vrakking, Marc J J

2009-10-01

The use of a new type in-vacuum pixel detector in velocity map imaging (VMI) is introduced. The Medipix2 and Timepix semiconductor pixel detectors (256 x 256 square pixels, 55 x 55 microm2) are well suited for charged particle detection. They offer high resolution, low noise, and high quantum efficiency. The Medipix2 chip allows double energy discrimination by offering a low and a high energy threshold. The Timepix detector allows to record the incidence time of a particle with a temporal resolution of 10 ns and a dynamic range of 160 micros. Results of the first time application of the Medipix2 detector to VMI are presented, investigating the quantum efficiency as well as the possibility to operate at increased background pressure in the vacuum chamber.

MCT-Based LWIR and VLWIR 2D Focal Plane Detector Arrays for Low Dark Current Applications at AIM

NASA Astrophysics Data System (ADS)

Hanna, S.; Eich, D.; Mahlein, K.-M.; Fick, W.; Schirmacher, W.; Thöt, R.; Wendler, J.; Figgemeier, H.

2016-09-01

We present our latest results on n-on- p as well as on p-on- n low dark current planar mercury cadmium telluride (MCT) photodiode technology long wavelength infrared (LWIR) and very long wavelength infrared (VLWIR) two-dimensional focal plane arrays (FPAs) with quantum efficiency (QE) cut-off wavelength >11 μm at 80 K and a 512 × 640 pixel format FPA at 20 μm pitch stitched from two 512 × 320 pixel photodiode arrays. Significantly reduced dark currents as compared with Tennant's "Rule 07" are demonstrated in both polarities while retaining good detection efficiency ≥60% for operating temperatures between 30 K and 100 K. This allows for the same dark current performance at 20 K higher operating temperature than with previous AIM INFRAROT-MODULE GmbH (AIM) technology. For p-on- n LWIR MCT FPAs, broadband photoresponse nonuniformity of only about 1.2% is achieved at 55 K with low defective pixel numbers. For an n-on- p VLWIR MCT FPA with 13.6 μm cut-off at 55 K, excellent photoresponse nonuniformity of about 3.1% is achieved at moderate defective pixel numbers. This advancement in detector technology paves the way for outstanding signal-to-noise ratio performance infrared detection, enabling cutting-edge next-generation LWIR/VLWIR detectors for space instruments and devices with higher operating temperature and low size, weight, and power for field applications.

A review of advances in pixel detectors for experiments with high rate and radiation

NASA Astrophysics Data System (ADS)

Garcia-Sciveres, Maurice; Wermes, Norbert

2018-06-01

The large Hadron collider (LHC) experiments ATLAS and CMS have established hybrid pixel detectors as the instrument of choice for particle tracking and vertexing in high rate and radiation environments, as they operate close to the LHC interaction points. With the high luminosity-LHC upgrade now in sight, for which the tracking detectors will be completely replaced, new generations of pixel detectors are being devised. They have to address enormous challenges in terms of data throughput and radiation levels, ionizing and non-ionizing, that harm the sensing and readout parts of pixel detectors alike. Advances in microelectronics and microprocessing technologies now enable large scale detector designs with unprecedented performance in measurement precision (space and time), radiation hard sensors and readout chips, hybridization techniques, lightweight supports, and fully monolithic approaches to meet these challenges. This paper reviews the world-wide effort on these developments.

Characterisation of the high dynamic range Large Pixel Detector (LPD) and its use at X-ray free electron laser sources

NASA Astrophysics Data System (ADS)

Veale, M. C.; Adkin, P.; Booker, P.; Coughlan, J.; French, M. J.; Hart, M.; Nicholls, T.; Schneider, A.; Seller, P.; Pape, I.; Sawhney, K.; Carini, G. A.; Hart, P. A.

2017-12-01

The STFC Rutherford Appleton Laboratory have delivered the Large Pixel Detector (LPD) for MHz frame rate imaging at the European XFEL. The detector system has an active area of 0.5 m × 0.5 m and consists of a million pixels on a 500 μm pitch. Sensors have been produced from 500 μm thick Hammamatsu silicon tiles that have been bump bonded to the readout ASIC using a silver epoxy and gold stud technique. Each pixel of the detector system is capable of measuring 105 12 keV photons per image readout at 4.5 MHz. In this paper results from the testing of these detectors at the Diamond Light Source and the Linac Coherent Light Source (LCLS) are presented. The performance of the detector in terms of linearity, spatial uniformity and the performance of the different ASIC gain stages is characterised.

Evaluation of a CdTe semiconductor based compact γ camera for sentinel lymph node imaging.

PubMed

Russo, Paolo; Curion, Assunta S; Mettivier, Giovanni; Esposito, Michela; Aurilio, Michela; Caracò, Corradina; Aloj, Luigi; Lastoria, Secondo

2011-03-01

The authors assembled a prototype compact gamma-ray imaging probe (MediPROBE) for sentinel lymph node (SLN) localization. This probe is based on a semiconductor pixel detector. Its basic performance was assessed in the laboratory and clinically in comparison with a conventional gamma camera. The room-temperature CdTe pixel detector (1 mm thick) has 256 x 256 square pixels arranged with a 55 microm pitch (sensitive area 14.08 x 14.08 mm2), coupled pixel-by-pixel via bump-bonding to the Medipix2 photon-counting readout CMOS integrated circuit. The imaging probe is equipped with a set of three interchangeable knife-edge pinhole collimators (0.94, 1.2, or 2.1 mm effective diameter at 140 keV) and its focal distance can be regulated in order to set a given field of view (FOV). A typical FOV of 70 mm at 50 mm skin-to-collimator distance corresponds to a minification factor 1:5. The detector is operated at a single low-energy threshold of about 20 keV. For 99 mTc, at 50 mm distance, a background-subtracted sensitivity of 6.5 x 10(-3) cps/kBq and a system spatial resolution of 5.5 mm FWHM were obtained for the 0.94 mm pinhole; corresponding values for the 2.1 mm pinhole were 3.3 x 10(-2) cps/kBq and 12.6 mm. The dark count rate was 0.71 cps. Clinical images in three patients with melanoma indicate detection of the SLNs with acquisition times between 60 and 410 s with an injected activity of 26 MBq 99 mTc and prior localization with standard gamma camera lymphoscintigraphy. The laboratory performance of this imaging probe is limited by the pinhole collimator performance and the necessity of working in minification due to the limited detector size. However, in clinical operative conditions, the CdTe imaging probe was effective in detecting SLNs with adequate resolution and an acceptable sensitivity. Sensitivity is expected to improve with the future availability of a larger CdTe detector permitting operation at shorter distances from the patient skin.

Design of a QA method to characterize submillimeter-sized PBS beam properties using a 2D ionization chamber array

NASA Astrophysics Data System (ADS)

Lin, Yuting; Bentefour, Hassan; Flanz, Jacob; Kooy, Hanne; Clasie, Benjamin

2018-05-01

Pencil beam scanning (PBS) periodic quality assurance (QA) programs ensure the beam delivered to patients is within technical specifications. Two critical specifications for PBS delivery are the beam width and position. The aim of this study is to investigate whether a 2D ionization chamber array, such as the MatriXX detector (IBA Dosimetry, Schwarzenbruck, Germany), can be used to characterize submillimeter-sized PBS beam properties. The motivation is to use standard equipment, which may have pixel spacing coarser than the pencil beam size, and simplify QA workflow. The MatriXX pixels are cylindrical in shape with 4.5 mm diameter and are spaced 7.62 mm from center to center. Two major effects limit the ability of using the MatriXX to measure the spot position and width accurately. The first effect is that too few pixels sample the Gaussian shaped pencil beam profile and the second effect is volume averaging of the Gaussian profile over the pixel sensitive volumes. We designed a method that overcomes both limitations and hence enables the use of the MatriXX to characterize sub-millimeter-sized PBS beam properties. This method uses a cross-like irradiation pattern that is designed to increase the number of sampling data points and a modified Gaussian fitting technique to correct for volume averaging effects. Detector signals were calculated in this study and random noise and setup errors were added to simulate measured data. With the techniques developed in this work, the MatriXX detector can be used to characterize the position and width of sub-millimeter, σ  =  0.7 mm, sized pencil beams with uncertainty better than 3% relative to σ. With the irradiation only covering 60% of the MatriXX, the position and width of σ  =  0.9 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. If one were to not use a cross-like irradiation pattern, then the position and width of σ  =  3.6 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. If one were to not use a cross-like pattern nor volume averaging corrections, then the position and width of σ  =  5.0 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. This work helps to simplify periodic QA in proton therapy because more routinely used ionization chamber arrays can be used to characterize narrow pencil beam properties.

Design of a QA method to characterize submillimeter-sized PBS beam properties using a 2D ionization chamber array.

PubMed

Lin, Yuting; Bentefour, Hassan; Flanz, Jacob; Kooy, Hanne; Clasie, Benjamin

2018-05-15

Pencil beam scanning (PBS) periodic quality assurance (QA) programs ensure the beam delivered to patients is within technical specifications. Two critical specifications for PBS delivery are the beam width and position. The aim of this study is to investigate whether a 2D ionization chamber array, such as the MatriXX detector (IBA Dosimetry, Schwarzenbruck, Germany), can be used to characterize submillimeter-sized PBS beam properties. The motivation is to use standard equipment, which may have pixel spacing coarser than the pencil beam size, and simplify QA workflow. The MatriXX pixels are cylindrical in shape with 4.5 mm diameter and are spaced 7.62 mm from center to center. Two major effects limit the ability of using the MatriXX to measure the spot position and width accurately. The first effect is that too few pixels sample the Gaussian shaped pencil beam profile and the second effect is volume averaging of the Gaussian profile over the pixel sensitive volumes. We designed a method that overcomes both limitations and hence enables the use of the MatriXX to characterize sub-millimeter-sized PBS beam properties. This method uses a cross-like irradiation pattern that is designed to increase the number of sampling data points and a modified Gaussian fitting technique to correct for volume averaging effects. Detector signals were calculated in this study and random noise and setup errors were added to simulate measured data. With the techniques developed in this work, the MatriXX detector can be used to characterize the position and width of sub-millimeter, σ  =  0.7 mm, sized pencil beams with uncertainty better than 3% relative to σ. With the irradiation only covering 60% of the MatriXX, the position and width of σ  =  0.9 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. If one were to not use a cross-like irradiation pattern, then the position and width of σ  =  3.6 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. If one were to not use a cross-like pattern nor volume averaging corrections, then the position and width of σ  =  5.0 mm sized pencil beams can be determined with uncertainty better than 3% relative to σ. This work helps to simplify periodic QA in proton therapy because more routinely used ionization chamber arrays can be used to characterize narrow pencil beam properties.

Qualification and calibration tests of detector modules for the CMS Pixel Phase 1 upgrade

NASA Astrophysics Data System (ADS)

Zhu, D.; Backhaus, M.; Berger, P.; Meinhard, M.; Starodumov, A.; Tavolaro, V.

2018-01-01

In high energy particle physics, accelerator- and detector-upgrades always go hand in hand. The instantaneous luminosity of the Large Hadron Collider will increase to up to L = 2×1034cm-2s-1 during Run 2 until 2023. In order to cope with such luminosities, the pixel detector of the CMS experiment has been replaced early 2017. The so-called CMS Pixel phase 1 upgrade detector consists of 1184 modules with new design. An important production step is the module qualification and calibration, ensuring their proper functionality within the detector. This paper summarizes the qualification and calibration tests and results of modules used in the innermost two detector layers with focus on methods using module-internal calibration signals. Extended characterizations on pixel level such as electronic noise and bump bond connectivity, optimization of operational parameters, sensor quality and thermal stress resistance were performed using a customized setup with controlled environment. It could be shown that the selected modules have on average 0.55‰ ± 0.01‰ defective pixels and that all performance parameters stay within their specifications.

Development and characterization of high-resolution neutron pixel detectors based on Timepix read-out chips

NASA Astrophysics Data System (ADS)

Krejci, F.; Zemlicka, J.; Jakubek, J.; Dudak, J.; Vavrik, D.; Köster, U.; Atkins, D.; Kaestner, A.; Soltes, J.; Viererbl, L.; Vacik, J.; Tomandl, I.

2016-12-01

Using a suitable isotope such as 6Li and 10B semiconductor hybrid pixel detectors can be successfully adapted for position sensitive detection of thermal and cold neutrons via conversion into energetic light ions. The adapted devices then typically provides spatial resolution at the level comparable to the pixel pitch (55 μm) and sensitive area of about few cm2. In this contribution, we describe further progress in neutron imaging performance based on the development of a large-area hybrid pixel detector providing practically continuous neutron sensitive area of 71 × 57 mm2. The measurements characterising the detector performance at the cold neutron imaging instrument ICON at PSI and high-flux imaging beam-line Neutrograph at ILL are presented. At both facilities, high-resolution high-contrast neutron radiography with the newly developed detector has been successfully applied for objects which imaging were previously difficult with hybrid pixel technology (such as various composite materials, objects of cultural heritage etc.). Further, a significant improvement in the spatial resolution of neutron radiography with hybrid semiconductor pixel detector based on the fast read-out Timepix-based detector is presented. The system is equipped with a thin planar 6LiF convertor operated effectively in the event-by-event mode enabling position sensitive detection with spatial resolution better than 10 μm.

4.3 μm quantum cascade detector in pixel configuration.

PubMed

Harrer, A; Schwarz, B; Schuler, S; Reininger, P; Wirthmüller, A; Detz, H; MacFarland, D; Zederbauer, T; Andrews, A M; Rothermund, M; Oppermann, H; Schrenk, W; Strasser, G

2016-07-25

We present the design simulation and characterization of a quantum cascade detector operating at 4.3μm wavelength. Array integration and packaging processes were investigated. The device operates in the 4.3μm CO₂ absorption region and consists of 64 pixels. The detector is designed fully compatible to standard processing and material growth methods for scalability to large pixel counts. The detector design is optimized for a high device resistance at elevated temperatures. A QCD simulation model was enhanced for resistance and responsivity optimization. The substrate illuminated pixels utilize a two dimensional Au diffraction grating to couple the light to the active region. A single pixel responsivity of 16mA/W at room temperature with a specific detectivity D^* of 5⋅10⁷ cmHz/W was measured.

The Belle II DEPFET pixel detector

NASA Astrophysics Data System (ADS)

Lütticke, F.

2013-02-01

The existing Japanese Flavour Factory (KEKB) is currently being upgraded and is foreseen to be comissioned by 2014. The new e+e- collider (SuperKEKB) will have an instantaneous luminosity of 8 × 1035cm-2s-1, 40 times higher than the current world record set by KEKB. In order to handle the increased event rate and the higher background and provide high data quality, the Belle detector is upgraded to Belle II. The increased particle rate requires a new vertex pixel detector with high granularity. This silicon detector will be based on DEPFET technology and will consist of two layers of active pixel sensors. By integrating a field effect transistor into every pixel on top of a fully depleted bulk, the DEPFET technology combines detection and in-pixel amplification. This technology allows good signal to noise performance with a very low material budget.

Pixelated transmission-mode diamond X-ray detector

PubMed Central

Zhou, Tianyi; Ding, Wenxiang; Gaowei, Mengjia; De Geronimo, Gianluigi; Bohon, Jen; Smedley, John; Muller, Erik

2015-01-01

Fabrication and testing of a prototype transmission-mode pixelated diamond X-ray detector (pitch size 60–100 µm), designed to simultaneously measure the flux, position and morphology of an X-ray beam in real time, are described. The pixel density is achieved by lithographically patterning vertical stripes on the front and horizontal stripes on the back of an electronic-grade chemical vapor deposition single-crystal diamond. The bias is rotated through the back horizontal stripes and the current is read out on the front vertical stripes at a rate of ∼1 kHz, which leads to an image sampling rate of ∼30 Hz. This novel signal readout scheme was tested at beamline X28C at the National Synchrotron Light Source (white beam, 5–15 keV) and at beamline G3 at the Cornell High Energy Synchrotron Source (monochromatic beam, 11.3 keV) with incident beam flux ranges from 1.8 × 10−2 to 90 W mm−2. Test results show that the novel detector provides precise beam position (positional noise within 1%) and morphology information (error within 2%), with an additional software-controlled single channel mode providing accurate flux measurement (fluctuation within 1%). PMID:26524304

Challenges, constraints, and results of lens design for 17 micron-bolometer focal plane arrays in 8-12 micron waveband

NASA Astrophysics Data System (ADS)

Schuster, Norbert; Franks, John

2011-06-01

In the 8-12 micron waveband Focal Plane Arrays (FPA) are available with a 17 micron pixel pitch in different arrays sizes (e.g. 512 x 480 pixels and 320 x 240 pixels) and with excellent electrical properties. Many applications become possible using this new type of IR-detector which will become the future standard in uncooled technology. Lenses with an f-number faster than f/1.5 minimize the diffraction impact on the spatial resolution and guarantee a high thermal resolution for uncooled cameras. Both effects will be quantified. The distinction between Traditional f-number (TF) and Radiometric f-number (RF) is discussed. Lenses with different focal lengths are required for applications in a variety of markets. They are classified by their Horizontal field of view (HFOV). Respecting the requirements for high volume markets, several two lens solutions will be discussed. A commonly accepted parameter of spatial resolution is the Modulation Transfer Function (MTF)-value at the Nyquist frequency of the detector (here 30cy/mm). This parameter of resolution will be presented versus field of view. Wide Angle and Super Wide Angle lenses are susceptible to low relative illumination in the corner of the detector. Measures to reduce this drop to an acceptable value are presented.

Non-Destructive Study of Bulk Crystallinity and Elemental Composition of Natural Gold Single Crystal Samples by Energy-Resolved Neutron Imaging

PubMed Central

Tremsin, Anton S.; Rakovan, John; Shinohara, Takenao; Kockelmann, Winfried; Losko, Adrian S.; Vogel, Sven C.

2017-01-01

Energy-resolved neutron imaging enables non-destructive analyses of bulk structure and elemental composition, which can be resolved with high spatial resolution at bright pulsed spallation neutron sources due to recent developments and improvements of neutron counting detectors. This technique, suitable for many applications, is demonstrated here with a specific study of ~5–10 mm thick natural gold samples. Through the analysis of neutron absorption resonances the spatial distribution of palladium (with average elemental concentration of ~0.4 atom% and ~5 atom%) is mapped within the gold samples. At the same time, the analysis of coherent neutron scattering in the thermal and cold energy regimes reveals which samples have a single-crystalline bulk structure through the entire sample volume. A spatially resolved analysis is possible because neutron transmission spectra are measured simultaneously on each detector pixel in the epithermal, thermal and cold energy ranges. With a pixel size of 55 μm and a detector-area of 512 by 512 pixels, a total of 262,144 neutron transmission spectra are measured concurrently. The results of our experiments indicate that high resolution energy-resolved neutron imaging is a very attractive analytical technique in cases where other conventional non-destructive methods are ineffective due to sample opacity. PMID:28102285

Test beam performance measurements for the Phase I upgrade of the CMS pixel detector

NASA Astrophysics Data System (ADS)

Dragicevic, M.; Friedl, M.; Hrubec, J.; Steininger, H.; Gädda, A.; Härkönen, J.; Lampén, T.; Luukka, P.; Peltola, T.; Tuominen, E.; Tuovinen, E.; Winkler, A.; Eerola, P.; Tuuva, T.; Baulieu, G.; Boudoul, G.; Caponetto, L.; Combaret, C.; Contardo, D.; Dupasquier, T.; Gallbit, G.; Lumb, N.; Mirabito, L.; Perries, S.; Vander Donckt, M.; Viret, S.; Bonnin, C.; Charles, L.; Gross, L.; Hosselet, J.; Tromson, D.; Feld, L.; Karpinski, W.; Klein, K.; Lipinski, M.; Pierschel, G.; Preuten, M.; Rauch, M.; Wlochal, M.; Aldaya, M.; Asawatangtrakuldee, C.; Beernaert, K.; Bertsche, D.; Contreras-Campana, C.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Gallo, E.; Garay Garcia, J.; Hansen, K.; Haranko, M.; Harb, A.; Hauk, J.; Keaveney, J.; Kalogeropoulos, A.; Kleinwort, C.; Lohmann, W.; Mankel, R.; Maser, H.; Mittag, G.; Muhl, C.; Mussgiller, A.; Pitzl, D.; Reichelt, O.; Savitskyi, M.; Schütze, P.; Sola, V.; Spannagel, S.; Walsh, R.; Zuber, A.; Biskop, H.; Buhmann, P.; Centis-Vignali, M.; Garutti, E.; Haller, J.; Hoffmann, M.; Klanner, R.; Lapsien, T.; Matysek, M.; Perieanu, A.; Scharf, Ch.; Schleper, P.; Schmidt, A.; Schwandt, J.; Sonneveld, J.; Steinbrück, G.; Vormwald, B.; Wellhausen, J.; Abbas, M.; Amstutz, C.; Barvich, T.; Barth, Ch.; Boegelspacher, F.; De Boer, W.; Butz, E.; Casele, M.; Colombo, F.; Dierlamm, A.; Freund, B.; Hartmann, F.; Heindl, S.; Husemann, U.; Kornmeyer, A.; Kudella, S.; Muller, Th.; Simonis, H. J.; Steck, P.; Weber, M.; Weiler, Th.; Kiss, T.; Siklér, F.; Tölyhi, T.; Veszprémi, V.; Cariola, P.; Creanza, D.; De Palma, M.; De Robertis, G.; Fiore, L.; Franco, M.; Loddo, F.; Sala, G.; Silvestris, L.; Maggi, G.; My, S.; Selvaggi, G.; Albergo, S.; Cappello, G.; Costa, S.; Di Mattia, A.; Giordano, F.; Potenza, R.; Saizu, M. A.; Tricomi, A.; Tuve, C.; Focardi, E.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Malvezzi, S.; Manzoni, R. A.; Menasce, D.; Moroni, L.; Pedrini, D.; Azzi, P.; Bacchetta, N.; Bisello, D.; Dall'Osso, M.; Pozzobon, N.; Tosi, M.; Alunni Solestizi, L.; Biasini, M.; Bilei, G. M.; Cecchi, C.; Checcucci, B.; Ciangottini, D.; Fanò, L.; Gentsos, C.; Ionica, M.; Leonardi, R.; Manoni, E.; Mantovani, G.; Marconi, S.; Mariani, V.; Menichelli, M.; Modak, A.; Morozzi, A.; Moscatelli, F.; Passeri, D.; Placidi, P.; Postolache, V.; Rossi, A.; Saha, A.; Santocchia, A.; Storchi, L.; Spiga, D.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Basti, A.; Boccali, T.; Borrello, L.; Bosi, F.; Castaldi, R.; Ceccanti, M.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Magazzu, G.; Mammini, P.; Mariani, F.; Mazzoni, E.; Messineo, A.; Moggi, A.; Morsani, F.; Palla, F.; Palmonari, F.; Profeti, A.; Raffaelli, F.; Ragonesi, A.; Rizzi, A.; Soldani, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Abbaneo, D.; Ahmed, I.; Albert, E.; Auzinger, G.; Berruti, G.; Bonnaud, J.; Daguin, J.; D'Auria, A.; Detraz, S.; Dondelewski, O.; Engegaard, B.; Faccio, F.; Frank, N.; Gill, K.; Honma, A.; Kornmayer, A.; Labaza, A.; Manolescu, F.; McGill, I.; Mersi, S.; Michelis, S.; Onnela, A.; Ostrega, M.; Pavis, S.; Peisert, A.; Pernot, J.-F.; Petagna, P.; Postema, H.; Rapacz, K.; Sigaud, C.; Tropea, P.; Troska, J.; Tsirou, A.; Vasey, F.; Verlaat, B.; Vichoudis, P.; Zwalinski, L.; Bachmair, F.; Becker, R.; di Calafiori, D.; Casal, B.; Berger, P.; Djambazov, L.; Donega, M.; Grab, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Meinhard, M.; Perozzi, L.; Roeser, U.; Starodumov, A.; Tavolaro, V.; Wallny, R.; Zhu, D.; Amsler, C.; Bösiger, K.; Caminada, L.; Canelli, F.; Chiochia, V.; de Cosa, A.; Galloni, C.; Hreus, T.; Kilminster, B.; Lange, C.; Maier, R.; Ngadiuba, J.; Pinna, D.; Robmann, P.; Taroni, S.; Yang, Y.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Kaestli, H.-C.; Kotlinski, D.; Langenegger, U.; Meier, B.; Rohe, T.; Streuli, S.; Chen, P.-H.; Dietz, C.; Fiori, F.; Grundler, U.; Hou, W.-S.; Lu, R.-S.; Moya, M.; Tsai, J.-F.; Tzeng, Y. M.; Cussans, D.; Goldstein, J.; Grimes, M.; Newbold, D.; Hobson, P.; Reid, I. D.; Auzinger, G.; Bainbridge, R.; Dauncey, P.; Hall, G.; James, T.; Magnan, A.-M.; Pesaresi, M.; Raymond, D. M.; Uchida, K.; Durkin, T.; Harder, K.; Shepherd-Themistocleous, C.; Chertok, M.; Conway, J.; Conway, R.; Flores, C.; Lander, R.; Pellett, D.; Ricci-Tam, F.; Squires, M.; Thomson, J.; Yohay, R.; Burt, K.; Ellison, J.; Hanson, G.; Olmedo, M.; Si, W.; Yates, B. R.; Dominguez, A.; Bartek, R.; Bentele, B.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Apresyan, A.; Bolla, G.; Burkett, K.; Butler, J. N.; Canepa, A.; Cheung, H. W. K.; Christian, D.; Cooper, W. E.; Deptuch, G.; Derylo, G.; Gingu, C.; Grünendahl, S.; Hasegawa, S.; Hoff, J.; Howell, J.; Hrycyk, M.; Jindariani, S.; Johnson, M.; Kahlid, F.; Kwan, S.; Lei, C. M.; Lipton, R.; Lopes De Sá, R.; Liu, T.; Los, S.; Matulik, M.; Merkel, P.; Nahn, S.; Prosser, A.; Rivera, R.; Schneider, B.; Sellberg, G.; Shenai, A.; Siehl, K.; Spiegel, L.; Tran, N.; Uplegger, L.; Voirin, E.; Berry, D. R.; Chen, X.; Ennesser, L.; Evdokimov, A.; Gerber, C. E.; Makauda, S.; Mills, C.; Sandoval Gonzalez, I. D.; Alimena, J.; Antonelli, L. J.; Francis, B.; Hart, A.; Hill, C. S.; Parashar, N.; Stupak, J.; Bortoletto, D.; Bubna, M.; Hinton, N.; Jones, M.; Miller, D. H.; Shi, X.; Baringer, P.; Bean, A.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Schmitz, E.; Wilson, G.; Ivanov, A.; Mendis, R.; Mitchell, T.; Skhirtladze, N.; Taylor, R.; Anderson, I.; Fehling, D.; Gritsan, A.; Maksimovic, P.; Martin, C.; Nash, K.; Osherson, M.; Swartz, M.; Xiao, M.; Acosta, J. G.; Cremaldi, L. M.; Oliveros, S.; Perera, L.; Summers, D.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Gonzalez Suarez, R.; Monroy, J.; Siado, J.; Bartz, E.; Gershtein, Y.; Halkiadakis, E.; Kyriacou, S.; Lath, A.; Nash, K.; Osherson, M.; Schnetzer, S.; Stone, R.; Walker, M.; Malik, S.; Norberg, S.; Ramirez Vargas, J. E.; Alyari, M.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Kharchilava, A.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; McDermott, K.; Mirman, N.; Rinkevicius, A.; Ryd, A.; Salvati, E.; Skinnari, L.; Soffi, L.; Tao, Z.; Thom, J.; Tucker, J.; Zientek, M.; Akgün, B.; Ecklund, K. M.; Kilpatrick, M.; Nussbaum, T.; Zabel, J.; D'Angelo, P.; Johns, W.; Rose, K.; Choudhury, S.; Korol, I.; Seitz, C.; Vargas Trevino, A.; Dolinska, G.

2017-05-01

A new pixel detector for the CMS experiment was built in order to cope with the instantaneous luminosities anticipated for the Phase I Upgrade of the LHC . The new CMS pixel detector provides four-hit tracking with a reduced material budget as well as new cooling and powering schemes. A new front-end readout chip mitigates buffering and bandwidth limitations, and allows operation at low comparator thresholds. In this paper, comprehensive test beam studies are presented, which have been conducted to verify the design and to quantify the performance of the new detector assemblies in terms of tracking efficiency and spatial resolution. Under optimal conditions, the tracking efficiency is 99.95 ± 0.05%, while the intrinsic spatial resolutions are 4.80 ± 0.25 μm and 7.99 ± 0.21 μm along the 100 μm and 150 μm pixel pitch, respectively. The findings are compared to a detailed Monte Carlo simulation of the pixel detector and good agreement is found.

A kilo-pixel imaging system for future space based far-infrared observatories using microwave kinetic inductance detectors

NASA Astrophysics Data System (ADS)

Baselmans, J. J. A.; Bueno, J.; Yates, S. J. C.; Yurduseven, O.; Llombart, N.; Karatsu, K.; Baryshev, A. M.; Ferrari, L.; Endo, A.; Thoen, D. J.; de Visser, P. J.; Janssen, R. M. J.; Murugesan, V.; Driessen, E. F. C.; Coiffard, G.; Martin-Pintado, J.; Hargrave, P.; Griffin, M.

2017-05-01

Aims: Future astrophysics and cosmic microwave background space missions operating in the far-infrared to millimetre part of the spectrum will require very large arrays of ultra-sensitive detectors in combination with high multiplexing factors and efficient low-noise and low-power readout systems. We have developed a demonstrator system suitable for such applications. Methods: The system combines a 961 pixel imaging array based upon Microwave Kinetic Inductance Detectors (MKIDs) with a readout system capable of reading out all pixels simultaneously with only one readout cable pair and a single cryogenic amplifier. We evaluate, in a representative environment, the system performance in terms of sensitivity, dynamic range, optical efficiency, cosmic ray rejection, pixel-pixel crosstalk and overall yield at an observation centre frequency of 850 GHz and 20% fractional bandwidth. Results: The overall system has an excellent sensitivity, with an average detector sensitivity < NEPdet> =3×10-19 WHz measured using a thermal calibration source. At a loading power per pixel of 50 fW we demonstrate white, photon noise limited detector noise down to 300 mHz. The dynamic range would allow the detection of 1 Jy bright sources within the field of view without tuning the readout of the detectors. The expected dead time due to cosmic ray interactions, when operated in an L2 or a similar far-Earth orbit, is found to be <4%. Additionally, the achieved pixel yield is 83% and the crosstalk between the pixels is <-30 dB. Conclusions: This demonstrates that MKID technology can provide multiplexing ratios on the order of a 1000 with state-of-the-art single pixel performance, and that the technology is now mature enough to be considered for future space based observatories and experiments.

3-D Spatial Resolution of 350 μm Pitch Pixelated CdZnTe Detectors for Imaging Applications.

PubMed

Yin, Yongzhi; Chen, Ximeng; Wu, Heyu; Komarov, Sergey; Garson, Alfred; Li, Qiang; Guo, Qingzhen; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2013-02-01

We are currently investigating the feasibility of using highly pixelated Cadmium Zinc Telluride (CdZnTe) detectors for sub-500 μ m resolution PET imaging applications. A 20 mm × 20 mm × 5 mm CdZnTe substrate was fabricated with 350 μ m pitch pixels (250 μ m anode pixels with 100 μ m gap) and coplanar cathode. Charge sharing among the pixels of a 350 μ m pitch detector was studied using collimated 122 keV and 511 keV gamma ray sources. For a 350 μ m pitch CdZnTe detector, scatter plots of the charge signal of two neighboring pixels clearly show more charge sharing when the collimated beam hits the gap between adjacent pixels. Using collimated Co-57 and Ge-68 sources, we measured the count profiles and estimated the intrinsic spatial resolution of 350 μ m pitch detector biased at -1000 V. Depth of interaction was analyzed based on two methods, i.e., cathode/anode ratio and electron drift time, in both 122 keV and 511 keV measurements. For single-pixel photopeak events, a linear correlation between cathode/anode ratio and electron drift time was shown, which would be useful for estimating the DOI information and preserving image resolution in CdZnTe PET imaging applications.

3-D Spatial Resolution of 350 μm Pitch Pixelated CdZnTe Detectors for Imaging Applications

PubMed Central

Yin, Yongzhi; Chen, Ximeng; Wu, Heyu; Komarov, Sergey; Garson, Alfred; Li, Qiang; Guo, Qingzhen; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2016-01-01

We are currently investigating the feasibility of using highly pixelated Cadmium Zinc Telluride (CdZnTe) detectors for sub-500 μm resolution PET imaging applications. A 20 mm × 20 mm × 5 mm CdZnTe substrate was fabricated with 350 μm pitch pixels (250 μm anode pixels with 100 μm gap) and coplanar cathode. Charge sharing among the pixels of a 350 μm pitch detector was studied using collimated 122 keV and 511 keV gamma ray sources. For a 350 μm pitch CdZnTe detector, scatter plots of the charge signal of two neighboring pixels clearly show more charge sharing when the collimated beam hits the gap between adjacent pixels. Using collimated Co-57 and Ge-68 sources, we measured the count profiles and estimated the intrinsic spatial resolution of 350 μm pitch detector biased at −1000 V. Depth of interaction was analyzed based on two methods, i.e., cathode/anode ratio and electron drift time, in both 122 keV and 511 keV measurements. For single-pixel photopeak events, a linear correlation between cathode/anode ratio and electron drift time was shown, which would be useful for estimating the DOI information and preserving image resolution in CdZnTe PET imaging applications. PMID:28250476

Data Processing for a High Resolution Preclinical PET Detector Based on Philips DPC Digital SiPMs

NASA Astrophysics Data System (ADS)

Schug, David; Wehner, Jakob; Goldschmidt, Benjamin; Lerche, Christoph; Dueppenbecker, Peter Michael; Hallen, Patrick; Weissler, Bjoern; Gebhardt, Pierre; Kiessling, Fabian; Schulz, Volkmar

2015-06-01

In positron emission tomography (PET) systems, light sharing techniques are commonly used to readout scintillator arrays consisting of scintillation elements, which are smaller than the optical sensors. The scintillating element is then identified evaluating the signal heights in the readout channels using statistical algorithms, the center of gravity (COG) algorithm being the simplest and mostly used one. We propose a COG algorithm with a fixed number of input channels in order to guarantee a stable calculation of the position. The algorithm is implemented and tested with the raw detector data obtained with the Hyperion-II D preclinical PET insert which uses Philips Digital Photon Counting's (PDPC) digitial SiPMs. The gamma detectors use LYSO scintillator arrays with 30 ×30 crystals of 1 ×1 ×12 mm3 in size coupled to 4 ×4 PDPC DPC 3200-22 sensors (DPC) via a 2-mm-thick light guide. These self-triggering sensors are made up of 2 ×2 pixels resulting in a total of 64 readout channels. We restrict the COG calculation to a main pixel, which captures most of the scintillation light from a crystal, and its (direct and diagonal) neighboring pixels and reject single events in which this data is not fully available. This results in stable COG positions for a crystal element and enables high spatial image resolution. Due to the sensor layout, for some crystals it is very likely that a single diagonal neighbor pixel is missing as a result of the low light level on the corresponding DPC. This leads to a loss of sensitivity, if these events are rejected. An enhancement of the COG algorithm is proposed which handles the potentially missing pixel separately both for the crystal identification and the energy calculation. Using this advancement, we show that the sensitivity of the Hyperion-II D insert using the described scintillator configuration can be improved by 20-100% for practical useful readout thresholds of a single DPC pixel ranging from 17-52 photons. Furthermore, we show that the energy resolution of the scanner is superior for all readout thresholds if singles with a single missing pixel are accepted and correctly handled compared to the COG method only accepting singles with all neighbors present by 0-1.6% (relative difference). The presented methods can not only be applied to gamma detectors employing DPC sensors, but can be generalized to other similarly structured and self-triggering detectors, using light sharing techniques, as well.

PantherPix hybrid pixel γ-ray detector for radio-therapeutic applications

NASA Astrophysics Data System (ADS)

Neue, G.; Benka, T.; Havránek, M.; Hejtmánek, M.; Janoška, Z.; Kafka, V.; Korchak, O.; Lednický, D.; Marčišovská, M.; Marčišovský, M.; Popule, J.; Şmarhák, J.; Şvihra, P.; Tomášek, L.; Vrba, V.; Konček, O.; Semmler, M.

2018-02-01

This work focuses on the design of a semiconductor pixelated γ-ray camera with a pixel size of 1 mm2. The cost of semiconductor manufacturing is mainly driven by economies of scale, which makes silicon the cheapest semiconductor material due to its widespread utilization. The energy of γ-photons used in radiation therapy are in a range, in which the dominant interaction mechanism is Compton scattering in every conceivable sensor material. Since the Compton scattering cross section is linearly dependent upon Z, it is less rewarding to utilize high Z sensor materials, than it is in the case of X-ray detectors (X-rays interact also via the photoelectric effect whose cross section scales proportional to Zn, where n is ≈ 4,5). For the stated reasons it was decided to use the low Z material silicon (Z = 14) despite its worse detection efficiency. The proposed detector is designed as a portal detector to be used in radiation cancer therapy. The purpose of the detector is to ensure correct patient alignment, spatial dose monitoring and to provide the feedback necessary for an emergency shutdown should the spatial dose rate profile deviate from the treatment plan. Radiation therapy equipment is complex and thus failure prone and the consequences of malfunction are often life threatening. High spatial resolution and high detection efficiency are not a high design priority. The detector design priorities are focused up on radiation hardness, robustness and the ability to cover a large area cost efficiently. The quintessential idea of the PanterPix detector exploits the relaxed spatial resolution requirement to achieve the stated goals. The detector is composed of submodules, each submodule consisting of a Si sensor with an array of fully depleted detection diodes and 8 miniature custom design readout ASICs collecting and measuring the minuscule charge packets generated due to ionization in the PN junctions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Ling-Jian

A gamma ray detector apparatus comprises a solid state detector that includes a plurality of anode pixels and at least one cathode. The solid state detector is configured for receiving gamma rays during an interaction and inducing a signal in an anode pixel and in a cathode. An anode pixel readout circuit is coupled to the plurality of anode pixels and is configured to read out and process the induced signal in the anode pixel and provide triggering and addressing information. A waveform sampling circuit is coupled to the at least one cathode and configured to read out and processmore » the induced signal in the cathode and determine energy of the interaction, timing of the interaction, and depth of interaction.« less

Velocity map imaging using an in-vacuum pixel detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gademann, Georg; Huismans, Ymkje; Gijsbertsen, Arjan

The use of a new type in-vacuum pixel detector in velocity map imaging (VMI) is introduced. The Medipix2 and Timepix semiconductor pixel detectors (256x256 square pixels, 55x55 {mu}m{sup 2}) are well suited for charged particle detection. They offer high resolution, low noise, and high quantum efficiency. The Medipix2 chip allows double energy discrimination by offering a low and a high energy threshold. The Timepix detector allows to record the incidence time of a particle with a temporal resolution of 10 ns and a dynamic range of 160 {mu}s. Results of the first time application of the Medipix2 detector to VMImore » are presented, investigating the quantum efficiency as well as the possibility to operate at increased background pressure in the vacuum chamber.« less

X-ray characterization of a multichannel smart-pixel array detector.

PubMed

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 × 48 pixels, each 130 µm × 130 µm × 520 µm 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.

X-ray analog pixel array detector for single synchrotron bunch time-resolved imaging.

PubMed

Koerner, Lucas J; Gruner, Sol M

2011-03-01

Dynamic X-ray studies can reach temporal resolutions limited by only the X-ray pulse duration if the detector is fast enough to segregate synchrotron pulses. An analog integrating pixel array detector with in-pixel storage and temporal resolution of around 150 ns, sufficient to isolate pulses, is presented. Analog integration minimizes count-rate limitations and in-pixel storage captures successive pulses. Fundamental tests of noise and linearity as well as high-speed laser measurements are shown. The detector resolved individual bunch trains at the Cornell High Energy Synchrotron Source at levels of up to 3.7 × 10(3) X-rays per pixel per train. When applied to turn-by-turn X-ray beam characterization, single-shot intensity measurements were made with a repeatability of 0.4% and horizontal oscillations of the positron cloud were detected.

X-ray analog pixel array detector for single synchrotron bunch time-resolved imaging

PubMed Central

Koerner, Lucas J.; Gruner, Sol M.

2011-01-01

Dynamic X-ray studies can reach temporal resolutions limited by only the X-ray pulse duration if the detector is fast enough to segregate synchrotron pulses. An analog integrating pixel array detector with in-pixel storage and temporal resolution of around 150 ns, sufficient to isolate pulses, is presented. Analog integration minimizes count-rate limitations and in-pixel storage captures successive pulses. Fundamental tests of noise and linearity as well as high-speed laser measurements are shown. The detector resolved individual bunch trains at the Cornell High Energy Synchrotron Source at levels of up to 3.7 × 103 X-rays per pixel per train. When applied to turn-by-turn X-ray beam characterization, single-shot intensity measurements were made with a repeatability of 0.4% and horizontal oscillations of the positron cloud were detected. PMID:21335901

Pixel detectors in double beta decay experiments, a new approach for background reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jose, J. M.; Čermák, P.; Štekl, I.

Double beta decay (ββ) experiments are challenging frontiers in contemporary physics. These experiments have the potential to investigate more about neutrinos (eg. nature and mass). The main challenge for these experiments is the reduction of background. The group at IEAP, CTU in Prague is investigating a new approach using pixel detectors Timepix. Pixel detector offer background reduction capabilities with its ability to identify the particle interaction (from the 2D signature it generates). However, use of pixel detectors has some challenges such as the presence of readout electronics near the sensing medium and heat dissipation. Different aspects of pixel setup (identificationmore » of radio-impurities, selection of radio-pure materials) and proposed experimental setup are presented. Also, results of preliminary background measurements (performed on the surface and in the underground laboratories) using the prototype setups are presented.« less

An alternative approach to depth of field which avoids the blur circle and uses the pixel pitch

NASA Astrophysics Data System (ADS)

Schuster, Norbert

2015-09-01

Modern thermal imaging systems apply more and more uncooled detectors. High volume applications work with detectors which have a reduced pixel count (typical between 200x150 and 640x480). This shrinks the application of modern image treatment procedures like wave front coding. On the other hand side, uncooled detectors demand lenses with fast F-numbers near 1.0. Which are the limits on resolution if the target to analyze changes its distance to the camera system? The aim to implement lens arrangements without any focusing mechanism demands a deeper quantification of the Depth of Field problem. The proposed Depth of Field approach avoids the classic "accepted image blur circle". It bases on a camera specific depth of focus which is transformed in the object space by paraxial relations. The traditional RAYLEIGH's -criterion bases on the unaberrated Point Spread Function and delivers a first order relation for the depth of focus. Hence, neither the actual lens resolution neither the detector impact is considered. The camera specific depth of focus respects a lot of camera properties: Lens aberrations at actual F-number, detector size and pixel pitch. The through focus MTF is the base of the camera specific depth of focus. It has a nearly symmetric course around the maximum of sharp imaging. The through focus MTF is considered at detector's Nyquist frequency. The camera specific depth of focus is this the axial distance in front and behind of sharp image plane where the through focus MTF is <0.25. This camera specific depth of focus is transferred in the object space by paraxial relations. It follows a general applicable Depth of Field diagram which could be applied to lenses realizing a lateral magnification range -0.05…0. Easy to handle formulas are provided between hyperfocal distance and the borders of the Depth of Field in dependence on sharp distances. These relations are in line with the classical Depth of Field-theory. Thermal pictures, taken by different IR-camera cores, illustrate the new approach. The quite often requested graph "MTF versus distance" choses the half Nyquist frequency as reference. The paraxial transfer of the through focus MTF in object space distorts the MTF-curve: hard drop at closer distances than sharp distance, smooth drop at further distances. The formula of a general Diffraction-Limited-Through-Focus-MTF (DLTF) is deducted. Arbitrary detector-lens combinations could be discussed. Free variables in this analysis are waveband, aperture based F-number (lens) and pixel pitch (detector). The DLTF- discussion provides physical limits and technical requirements. The detector development with pixel pitches smaller than captured wavelength in the LWIR-region generates a special challenge for optical design.

III-V infrared research at the Jet Propulsion Laboratory

NASA Astrophysics Data System (ADS)

Gunapala, S. D.; Ting, D. Z.; Hill, C. J.; Soibel, A.; Liu, John; Liu, J. K.; Mumolo, J. M.; Keo, S. A.; Nguyen, J.; Bandara, S. V.; Tidrow, M. Z.

2009-08-01

Jet Propulsion Laboratory is actively developing the III-V based infrared detector and focal plane arrays (FPAs) for NASA, DoD, and commercial applications. Currently, we are working on multi-band Quantum Well Infrared Photodetectors (QWIPs), Superlattice detectors, and Quantum Dot Infrared Photodetector (QDIPs) technologies suitable for high pixel-pixel uniformity and high pixel operability large area imaging arrays. In this paper we report the first demonstration of the megapixel-simultaneously-readable and pixel-co-registered dual-band QWIP focal plane array (FPA). In addition, we will present the latest advances in QDIPs and Superlattice infrared detectors at the Jet Propulsion Laboratory.

Frequency-multiplexed bias and readout of a 16-pixel superconducting nanowire single-photon detector array

NASA Astrophysics Data System (ADS)

Doerner, S.; Kuzmin, A.; Wuensch, S.; Charaev, I.; Boes, F.; Zwick, T.; Siegel, M.

2017-07-01

We demonstrate a 16-pixel array of microwave-current driven superconducting nanowire single-photon detectors with an integrated and scalable frequency-division multiplexing architecture, which reduces the required number of bias and readout lines to a single microwave feed line. The electrical behavior of the photon-sensitive nanowires, embedded in a resonant circuit, as well as the optical performance and timing jitter of the single detectors is discussed. Besides the single pixel measurements, we also demonstrate the operation of a 16-pixel array with a temporal, spatial, and photon-number resolution.

Indium-bump-free antimonide superlattice membrane detectors on silicon substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zamiri, M., E-mail: mzamiri@chtm.unm.edu, E-mail: skrishna@chtm.unm.edu; Klein, B.; Schuler-Sandy, T.

2016-02-29

We present an approach to realize antimonide superlattices on silicon substrates without using conventional Indium-bump hybridization. In this approach, PIN superlattices are grown on top of a 60 nm Al{sub 0.6}Ga{sub 0.4}Sb sacrificial layer on a GaSb host substrate. Following the growth, the individual pixels are transferred using our epitaxial-lift off technique, which consists of a wet-etch to undercut the pixels followed by a dry-stamp process to transfer the pixels to a silicon substrate prepared with a gold layer. Structural and optical characterization of the transferred pixels was done using an optical microscope, scanning electron microscopy, and photoluminescence. The interface betweenmore » the transferred pixels and the new substrate was abrupt, and no significant degradation in the optical quality was observed. An Indium-bump-free membrane detector was then fabricated using this approach. Spectral response measurements provided a 100% cut-off wavelength of 4.3 μm at 77 K. The performance of the membrane detector was compared to a control detector on the as-grown substrate. The membrane detector was limited by surface leakage current. The proposed approach could pave the way for wafer-level integration of photonic detectors on silicon substrates, which could dramatically reduce the cost of these detectors.« less

Resolution studies with the DATURA beam telescope

NASA Astrophysics Data System (ADS)

Jansen, H.

2016-12-01

Detailed studies of the resolution of a EUDET-type beam telescope are carried out using the DATURA beam telescope as an example. The EUDET-type beam telescopes make use of CMOS MIMOSA 26 pixel detectors for particle tracking allowing for precise characterisation of particle-sensing devices. A profound understanding of the performance of the beam telescope as a whole is obtained by a detailed characterisation of the sensors themselves. The differential intrinsic resolution as measured in a MIMOSA 26 sensor is extracted using an iterative pull method, and various quantities that depend on the size of the cluster produced by a traversing charged particle are discussed: the residual distribution, the intra-pixel residual-width distribution and the intra-pixel density distribution of track incident positions.

Pixelated coatings and advanced IR coatings

NASA Astrophysics Data System (ADS)

Pradal, Fabien; Portier, Benjamin; Oussalah, Meihdi; Leplan, Hervé

2017-09-01

Reosc developed pixelated infrared coatings on detector. Reosc manufactured thick pixelated multilayer stacks on IR-focal plane arrays for bi-spectral imaging systems, demonstrating high filter performance, low crosstalk, and no deterioration of the device sensitivities. More recently, a 5-pixel filter matrix was designed and fabricated. Recent developments in pixelated coatings, shows that high performance infrared filters can be coated directly on detector for multispectral imaging. Next generation space instrument can benefit from this technology to reduce their weight and consumptions.

Characterisation of the high dynamic range Large Pixel Detector (LPD) and its use at X-ray free electron laser sources

DOE PAGES

Veale, M. C.; Adkin, P.; Booker, P.; ...

2017-12-04

The STFC Rutherford Appleton Laboratory have delivered the Large Pixel Detector (LPD) for MHz frame rate imaging at the European XFEL. The detector system has an active area of 0.5 m × 0.5 m and consists of a million pixels on a 500 μm pitch. Sensors have been produced from 500 μm thick Hammamatsu silicon tiles that have been bump bonded to the readout ASIC using a silver epoxy and gold stud technique. Each pixel of the detector system is capable of measuring 10 5 12 keV photons per image readout at 4.5 MHz. In this paper results from themore » testing of these detectors at the Diamond Light Source and the Linac Coherent Light Source (LCLS) are presented. As a result, the performance of the detector in terms of linearity, spatial uniformity and the performance of the different ASIC gain stages is characterised.« less

Characterisation of the high dynamic range Large Pixel Detector (LPD) and its use at X-ray free electron laser sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veale, M. C.; Adkin, P.; Booker, P.

The STFC Rutherford Appleton Laboratory have delivered the Large Pixel Detector (LPD) for MHz frame rate imaging at the European XFEL. The detector system has an active area of 0.5 m × 0.5 m and consists of a million pixels on a 500 μm pitch. Sensors have been produced from 500 μm thick Hammamatsu silicon tiles that have been bump bonded to the readout ASIC using a silver epoxy and gold stud technique. Each pixel of the detector system is capable of measuring 10 5 12 keV photons per image readout at 4.5 MHz. In this paper results from themore » testing of these detectors at the Diamond Light Source and the Linac Coherent Light Source (LCLS) are presented. As a result, the performance of the detector in terms of linearity, spatial uniformity and the performance of the different ASIC gain stages is characterised.« less

Characterization of a 2-mm thick, 16x16 Cadmium-Zinc-Telluride Pixel Array

NASA Technical Reports Server (NTRS)

Gaskin, Jessica; Richardson, Georgia; Mitchell, Shannon; Ramsey, Brian; Seller, Paul; Sharma, Dharma

2003-01-01

The detector under study is a 2-mm-thick, 16x16 Cadmium-Zinc-Telluride pixel array with a pixel pitch of 300 microns and inter-pixel gap of 50 microns. This detector is a precursor to that which will be used at the focal plane of the High Energy Replicated Optics (HERO) telescope currently being developed at Marshall Space Flight Center. With a telescope focal length of 6 meters, the detector needs to have a spatial resolution of around 200 microns in order to take full advantage of the HERO angular resolution. We discuss to what degree charge sharing will degrade energy resolution but will improve our spatial resolution through position interpolation. In addition, we discuss electric field modeling for this specific detector geometry and the role this mapping will play in terms of charge sharing and charge loss in the detector.

Modulation transfer function of partial gating detector by liquid crystal auto-controlling light intensity

NASA Astrophysics Data System (ADS)

Yang, Xusan; Tang, Yuanhe; Liu, Kai; Liu, Hanchen; Gao, Haiyang; Li, Qing; Zhang, Ruixia; Ye, Na; Liang, Yuan; Zhao, Gaoxiang

2008-12-01

Based on the electro-optical properties of liquid crystal, we have designed a novel partial gating detector. Liquid crystal can be taken to change its own transmission according to the light intensity outside. Every single pixel of the image is real-time modulated by liquid crystal, thus the strong light is weakened and low light goes through the detector normally .The purpose of partial-gating strong light (>105lx) can be achieved by this detector. The modulation transfer function (MTF) equations of the main optical sub-systems are calculated in this paper, they are liquid crystal panels, linear fiber panel and CCD array detector. According to the relevant size, the MTF value of this system is fitted out. The result is MTF= 0.518 at Nyquist frequency.

Elemental X-ray Imaging Using the Maia Detector Array: The Benefits and Challenges of Large Solid-Angle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryan, C.G.; De Geronimo, G.; Kirkham, R.

2009-11-13

The fundamental parameter method for quantitative SXRF and PIXE analysis and imaging using the dynamic analysis method is extended to model the changing X-ray yields and detector sensitivity with angle across large detector arrays. The method is implemented in the GeoPIXE software and applied to cope with the large solid-angle of the new Maia 384 detector array and its 96 detector prototype developed by CSIRO and BNL for SXRF imaging applications at the Australian and NSLS synchrotrons. Peak-to-background is controlled by mitigating charge-sharing between detectors through careful optimization of a patterned molybdenum absorber mask. A geological application demonstrates the capabilitymore » of the method to produce high definition elemental images up to {approx}100 M pixels in size.« less

The effect of defect cluster size and interpolation on radiographic image quality

NASA Astrophysics Data System (ADS)

Töpfer, Karin; Yip, Kwok L.

2011-03-01

For digital X-ray detectors, the need to control factory yield and cost invariably leads to the presence of some defective pixels. Recently, a standard procedure was developed to identify such pixels for industrial applications. However, no quality standards exist in medical or industrial imaging regarding the maximum allowable number and size of detector defects. While the answer may be application specific, the minimum requirement for any defect specification is that the diagnostic quality of the images be maintained. A more stringent criterion is to keep any changes in the images due to defects below the visual threshold. Two highly sensitive image simulation and evaluation methods were employed to specify the fraction of allowable defects as a function of defect cluster size in general radiography. First, the most critical situation of the defect being located in the center of the disease feature was explored using image simulation tools and a previously verified human observer model, incorporating a channelized Hotelling observer. Detectability index d' was obtained as a function of defect cluster size for three different disease features on clinical lung and extremity backgrounds. Second, four concentrations of defects of four different sizes were added to clinical images with subtle disease features and then interpolated. Twenty observers evaluated the images against the original on a single display using a 2-AFC method, which was highly sensitive to small changes in image detail. Based on a 50% just-noticeable difference, the fraction of allowed defects was specified vs. cluster size.

Vehicle and cargo container inspection system for drugs

NASA Astrophysics Data System (ADS)

Verbinski, Victor V.; Orphan, Victor J.

1999-06-01

A vehicle and cargo container inspection system has been developed which uses gamma-ray radiography to produce digital images useful for detection of drugs and other contraband. The system is comprised of a 1 Ci Cs137 gamma-ray source collimated into a fan beam which is aligned with a linear array of NaI gamma-ray detectors located on the opposite side of the container. The NaI detectors are operated in the pulse-counting mode. A digital image of the vehicle or container is obtained by moving the aligned source and detector array relative to the object. Systems have been demonstrated in which the object is stationary (source and detector array move on parallel tracks) and in which the object moves past a stationary source and detector array. Scanning speeds of ˜30 cm/s with a pixel size (at the object) of ˜1 cm have been achieved. Faster scanning speeds of ˜2 m/s have been demonstrated on railcars with more modest spatial resolution (4 cm pixels). Digital radiographic images are generated from the detector count rates. These images, recorded on a PC-based data acquisition and display system, are shown from several applications: 1) inspection of trucks and containers at a border crossing, 2) inspection of railcars at a border crossing, 3) inspection of outbound cargo containers for stolen automobiles, and 4) inspection of trucks and cars for terrorist bombs.

Quantification of the Conditioning Phase in Cooled Pixelated TlBr Detectors

NASA Astrophysics Data System (ADS)

Koehler, Will; He, Zhong; O'Neal, Sean; Yang, Hao; Kim, Hadong; Cirignano, Leonard; Shah, Kanai

2015-08-01

Thallium-bromide (TlBr) is currently under investigation as an alternative room-temperature semiconductor gamma-ray spectrometer due to its favorable material properties (large bandgap, high atomic numbers, and high density). Previous work has shown that 5 mm thick pixelated TlBr detectors can achieve sub-1% FWHM energy resolution at 662 keV for single-pixel events. These results are limited to - 20° C operation where detector performance is stable. During the first one to five days of applied bias at - 20° C, many TlBr detectors undergo a conditioning phase, where the energy resolution improves and the depth-dependent electron drift velocity stabilizes. In this work, the spectroscopic performance, drift velocity, and freed electron concentrations of multiple 5 mm thick pixelated TlBr detectors are monitored throughout the conditioning phase. Additionally, conditioning is performed twice on the same detector at different times to show that improvement mechanisms relax when the detector is stored without bias. We conclude that the improved spectroscopy results from internal electric field stabilization and uniformity caused by fewer trapped electrons.

Modeling radiation damage to pixel sensors in the ATLAS detector

NASA Astrophysics Data System (ADS)

Ducourthial, A.

2018-03-01

Silicon pixel detectors are at the core of the current and planned upgrade of the ATLAS detector at the Large Hadron Collider (LHC) . As the closest detector component to the interaction point, these detectors will be subject to a significant amount of radiation over their lifetime: prior to the High-Luminosity LHC (HL-LHC) [1], the innermost layers will receive a fluence in excess of 1015 neq/cm2 and the HL-LHC detector upgrades must cope with an order of magnitude higher fluence integrated over their lifetimes. Simulating radiation damage is essential in order to make accurate predictions for current and future detector performance that will enable searches for new particles and forces as well as precision measurements of Standard Model particles such as the Higgs boson. We present a digitization model that includes radiation damage effects on the ATLAS pixel sensors for the first time. In addition to thoroughly describing the setup, we present first predictions for basic pixel cluster properties alongside early studies with LHC Run 2 proton-proton collision data.

DEPFET pixel detector for future e-e+ experiments

NASA Astrophysics Data System (ADS)

Boronat, M.; DEPFET Collaboration

2016-04-01

The DEPFET Collaboration develops highly granular, ultra-thin pixel detectors for outstanding vertex reconstruction at future e+e- collider experiments. A DEPFET sensor provides, simultaneously, position sensitive detector capabilities and in-pixel amplification by the integration of a field effect transistor on a fully depleted silicon bulk. The characterization of the latest DEPFET prototypes has proven that a comfortable signal to noise ratio and excellent single point resolution can be achieved for a sensor thickness of 50 μm. A complete detector concept is being developed for the Belle II experiment at the new Japanese super flavor factory. The close to Belle related final auxiliary ASICs have been produced and found to operate a DEPFET pixel detector of the latest generation with the Belle II required read-out speed. DEPFET is not only the technology of choice for the Belle II vertex detector, but also a solid candidate for the International Linear Collider (ILC). Therefore, in this paper, the status of DEPFET R&D project is reviewed in the light of the requirements of the vertex detector at a future e+e- collider.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Becker, Julian; Tate, Mark W.; Shanks, Katherine S.

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,more » 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.« less

Study of cluster shapes in a monolithic active pixel detector

NASA Astrophysics Data System (ADS)

Maçzewski, ł.; Adamus, M.; Ciborowski, J.; Grzelak, G.; łużniak, P.; Nieżurawski, P.; Żarnecki, A. F.

2009-11-01

Beamstrahlung will constitute an important source of background in a pixel vertex detector at the future International Linear Collider. Electron and positron tracks of this origin impact the pixel planes at angles generally larger than those of secondary hadrons and the corresponding clusters are elongated. We report studies of cluster characteristics using test beam electron tracks incident at various angles on a MIMOSA-5 monolithic active pixel sensor matrix.

Simulation and Measurement of Absorbed Dose from 137 Cs Gammas Using a Si Timepix Detector

NASA Technical Reports Server (NTRS)

Stoffle, Nicholas; Pinsky, Lawrence; Empl, Anton; Semones, Edward

2011-01-01

The TimePix readout chip is a hybrid pixel detector with over 65k independent pixel elements. Each pixel contains its own circuitry for charge collection, counting logic, and readout. When coupled with a Silicon detector layer, the Timepix chip is capable of measuring the charge, and thus energy, deposited in the Silicon. Measurements using a NIST traceable 137Cs gamma source have been made at Johnson Space Center using such a Si Timepix detector, and this data is compared to simulations of energy deposition in the Si layer carried out using FLUKA.

Techniques for precise energy calibration of particle pixel detectors

NASA Astrophysics Data System (ADS)

Kroupa, M.; Campbell-Ricketts, T.; Bahadori, A.; Empl, A.

2017-03-01

We demonstrate techniques to improve the accuracy of the energy calibration of Timepix pixel detectors, used for the measurement of energetic particles. The typical signal from such particles spreads among many pixels due to charge sharing effects. As a consequence, the deposited energy in each pixel cannot be reconstructed unless the detector is calibrated, limiting the usability of such signals for calibration. To avoid this shortcoming, we calibrate using low energy X-rays. However, charge sharing effects still occur, resulting in part of the energy being deposited in adjacent pixels and possibly lost. This systematic error in the calibration process results in an error of about 5% in the energy measurements of calibrated devices. We use FLUKA simulations to assess the magnitude of charge sharing effects, allowing a corrected energy calibration to be performed on several Timepix pixel detectors and resulting in substantial improvement in energy deposition measurements. Next, we address shortcomings in calibration associated with the huge range (from kiloelectron-volts to megaelectron-volts) of energy deposited per pixel which result in a nonlinear energy response over the full range. We introduce a new method to characterize the non-linear response of the Timepix detectors at high input energies. We demonstrate improvement using a broad range of particle types and energies, showing that the new method reduces the energy measurement errors, in some cases by more than 90%.

Techniques for precise energy calibration of particle pixel detectors.

PubMed

Kroupa, M; Campbell-Ricketts, T; Bahadori, A; Empl, A

2017-03-01

We demonstrate techniques to improve the accuracy of the energy calibration of Timepix pixel detectors, used for the measurement of energetic particles. The typical signal from such particles spreads among many pixels due to charge sharing effects. As a consequence, the deposited energy in each pixel cannot be reconstructed unless the detector is calibrated, limiting the usability of such signals for calibration. To avoid this shortcoming, we calibrate using low energy X-rays. However, charge sharing effects still occur, resulting in part of the energy being deposited in adjacent pixels and possibly lost. This systematic error in the calibration process results in an error of about 5% in the energy measurements of calibrated devices. We use FLUKA simulations to assess the magnitude of charge sharing effects, allowing a corrected energy calibration to be performed on several Timepix pixel detectors and resulting in substantial improvement in energy deposition measurements. Next, we address shortcomings in calibration associated with the huge range (from kiloelectron-volts to megaelectron-volts) of energy deposited per pixel which result in a nonlinear energy response over the full range. We introduce a new method to characterize the non-linear response of the Timepix detectors at high input energies. We demonstrate improvement using a broad range of particle types and energies, showing that the new method reduces the energy measurement errors, in some cases by more than 90%.

Test beam performance measurements for the Phase I upgrade of the CMS pixel detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dragicevic, M.; Friedl, M.; Hrubec, J.

A new pixel detector for the CMS experiment was built in order to cope with the instantaneous luminosities anticipated for the Phase~I Upgrade of the LHC. The new CMS pixel detector provides four-hit tracking with a reduced material budget as well as new cooling and powering schemes. A new front-end readout chip mitigates buffering and bandwidth limitations, and allows operation at low comparator thresholds. Here in this paper, comprehensive test beam studies are presented, which have been conducted to verify the design and to quantify the performance of the new detector assemblies in terms of tracking efficiency and spatial resolution. Under optimal conditions, the tracking efficiency ismore » $$99.95\\pm0.05\\,\\%$$, while the intrinsic spatial resolutions are $$4.80\\pm0.25\\,\\mu \\mathrm{m}$$ and $$7.99\\pm0.21\\,\\mu \\mathrm{m}$$ along the $$100\\,\\mu \\mathrm{m}$$ and $$150\\,\\mu \\mathrm{m}$$ pixel pitch, respectively. The findings are compared to a detailed Monte Carlo simulation of the pixel detector and good agreement is found.« less

Test beam performance measurements for the Phase I upgrade of the CMS pixel detector

DOE PAGES

Dragicevic, M.; Friedl, M.; Hrubec, J.; ...

2017-05-30

A new pixel detector for the CMS experiment was built in order to cope with the instantaneous luminosities anticipated for the Phase~I Upgrade of the LHC. The new CMS pixel detector provides four-hit tracking with a reduced material budget as well as new cooling and powering schemes. A new front-end readout chip mitigates buffering and bandwidth limitations, and allows operation at low comparator thresholds. Here in this paper, comprehensive test beam studies are presented, which have been conducted to verify the design and to quantify the performance of the new detector assemblies in terms of tracking efficiency and spatial resolution. Under optimal conditions, the tracking efficiency ismore » $$99.95\\pm0.05\\,\\%$$, while the intrinsic spatial resolutions are $$4.80\\pm0.25\\,\\mu \\mathrm{m}$$ and $$7.99\\pm0.21\\,\\mu \\mathrm{m}$$ along the $$100\\,\\mu \\mathrm{m}$$ and $$150\\,\\mu \\mathrm{m}$$ pixel pitch, respectively. The findings are compared to a detailed Monte Carlo simulation of the pixel detector and good agreement is found.« less

A low-power CMOS readout IC design for bolometer applications

NASA Astrophysics Data System (ADS)

Galioglu, Arman; Abbasi, Shahbaz; Shafique, Atia; Ceylan, Ömer; Yazici, Melik; Kaynak, Mehmet; Durmaz, Emre C.; Arsoy, Elif Gul; Gurbuz, Yasar

2017-02-01

A prototype of a readout IC (ROIC) designed for use in high temperature coefficient of resistance (TCR) SiGe microbolometers is presented. The prototype ROIC architecture implemented is based on a bridge with active and blind bolometer pixels with a capacitive transimpedance amplifier (CTIA) input stage and column parallel integration with serial readout. The ROIC is designed for use in high (>= 4 %/K) TCR and high detector resistance Si/SiGe microbolometers with 17x17 μm2 pixel sizes in development. The prototype has been designed and fabricated in 0.25- μm SiGe:C BiCMOS process.

Angular resolution of the gaseous micro-pixel detector Gossip

NASA Astrophysics Data System (ADS)

Bilevych, Y.; Blanco Carballo, V.; van Dijk, M.; Fransen, M.; van der Graaf, H.; Hartjes, F.; Hessey, N.; Koppert, W.; Nauta, S.; Rogers, M.; Romaniouk, A.; Veenhof, R.

2011-06-01

Gossip is a gaseous micro-pixel detector with a very thin drift gap intended for a high rate environment like at the pixel layers of ATLAS at the sLHC. The detector outputs not only the crossing point of a traversing MIP, but also the angle of the track, thus greatly simplifying track reconstruction. In this paper we describe a testbeam experiment to examine the angular resolution of the reconstructed track segments in Gossip. We used here the low diffusion gas mixture DME/CO 2 50/50. An angular resolution of 20 mrad for perpendicular tracks could be obtained from a 1.5 mm thin drift volume. However, for the prototype detector used at the testbeam experiment, the resolution of slanting tracks was worsened by poor time resolution of the pixel chip used.

The future of RICH detectors through the light of the LHCb RICH

NASA Astrophysics Data System (ADS)

D'Ambrosio, C.; LHCb RICH Collaboration

2017-12-01

The limitations in performance of the present RICH system in the LHCb experiment are given by the natural chromatic dispersion of the gaseous Cherenkov radiator, the aberrations of the optical system and the pixel size of the photon detectors. Moreover, the overall PID performance can be affected by high detector occupancy as the pattern recognition becomes more difficult with high particle multiplicities. This paper shows a way to improve performance by systematically addressing each of the previously mentioned limitations. These ideas are applied in the present and future upgrade phases of the LHCb experiment. Although applied to specific circumstances, they are used as a paradigm on what is achievable in the development and realisation of high precision RICH detectors.

Investigation of the limitations of the highly pixilated CdZnTe detector for PET applications

PubMed Central

Komarov, Sergey; Yin, Yongzhi; Wu, Heyu; Wen, Jie; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2016-01-01

We are investigating the feasibility of a high resolution positron emission tomography (PET) insert device based on the CdZnTe detector with 350 μm anode pixel pitch to be integrated into a conventional animal PET scanner to improve its image resolution. In this paper, we have used a simplified version of the multi pixel CdZnTe planar detector, 5 mm thick with 9 anode pixels only. This simplified 9 anode pixel structure makes it possible to carry out experiments without a complete application-specific integrated circuits readout system that is still under development. Special attention was paid to the double pixel (or charge sharing) detections. The following characteristics were obtained in experiment: energy resolution full-width-at-half-maximum (FWHM) is 7% for single pixel and 9% for double pixel photoelectric detections of 511 keV gammas; timing resolution (FWHM) from the anode signals is 30 ns for single pixel and 35 ns for double pixel detections (for photoelectric interactions only the corresponding values are 20 and 25 ns); position resolution is 350 μm in x,y-plane and ~0.4 mm in depth-of-interaction. The experimental measurements were accompanied by Monte Carlo (MC) simulations to find a limitation imposed by spatial charge distribution. Results from MC simulations suggest the limitation of the intrinsic spatial resolution of the CdZnTe detector for 511 keV photoelectric interactions is 170 μm. The interpixel interpolation cannot recover the resolution beyond the limit mentioned above for photoelectric interactions. However, it is possible to achieve higher spatial resolution using interpolation for Compton scattered events. Energy and timing resolution of the proposed 350 μm anode pixel pitch detector is no better than 0.6% FWHM at 511 keV, and 2 ns FWHM, respectively. These MC results should be used as a guide to understand the performance limits of the pixelated CdZnTe detector due to the underlying detection processes, with the understanding of the inherent limitations of MC methods. PMID:23079763

Investigation of the limitations of the highly pixilated CdZnTe detector for PET applications.

PubMed

Komarov, Sergey; Yin, Yongzhi; Wu, Heyu; Wen, Jie; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2012-11-21

We are investigating the feasibility of a high resolution positron emission tomography (PET) insert device based on the CdZnTe detector with 350 µm anode pixel pitch to be integrated into a conventional animal PET scanner to improve its image resolution. In this paper, we have used a simplified version of the multi pixel CdZnTe planar detector, 5 mm thick with 9 anode pixels only. This simplified 9 anode pixel structure makes it possible to carry out experiments without a complete application-specific integrated circuits readout system that is still under development. Special attention was paid to the double pixel (or charge sharing) detections. The following characteristics were obtained in experiment: energy resolution full-width-at-half-maximum (FWHM) is 7% for single pixel and 9% for double pixel photoelectric detections of 511 keV gammas; timing resolution (FWHM) from the anode signals is 30 ns for single pixel and 35 ns for double pixel detections (for photoelectric interactions only the corresponding values are 20 and 25 ns); position resolution is 350 µm in x,y-plane and ∼0.4 mm in depth-of-interaction. The experimental measurements were accompanied by Monte Carlo (MC) simulations to find a limitation imposed by spatial charge distribution. Results from MC simulations suggest the limitation of the intrinsic spatial resolution of the CdZnTe detector for 511 keV photoelectric interactions is 170 µm. The interpixel interpolation cannot recover the resolution beyond the limit mentioned above for photoelectric interactions. However, it is possible to achieve higher spatial resolution using interpolation for Compton scattered events. Energy and timing resolution of the proposed 350 µm anode pixel pitch detector is no better than 0.6% FWHM at 511 keV, and 2 ns FWHM, respectively. These MC results should be used as a guide to understand the performance limits of the pixelated CdZnTe detector due to the underlying detection processes, with the understanding of the inherent limitations of MC methods.

Design considerations for a new, high resolution Micro-Angiographic Fluoroscope based on a CMOS sensor (MAF-CMOS).

PubMed

Loughran, Brendan; Swetadri Vasan, S N; Singh, Vivek; Ionita, Ciprian N; Jain, Amit; Bednarek, Daniel R; Titus, Albert; Rudin, Stephen

2013-03-06

The detectors that are used for endovascular image-guided interventions (EIGI), particularly for neurovascular interventions, do not provide clinicians with adequate visualization to ensure the best possible treatment outcomes. Developing an improved x-ray imaging detector requires the determination of estimated clinical x-ray entrance exposures to the detector. The range of exposures to the detector in clinical studies was found for the three modes of operation: fluoroscopic mode, high frame-rate digital angiographic mode (HD fluoroscopic mode), and DSA mode. Using these estimated detector exposure ranges and available CMOS detector technical specifications, design requirements were developed to pursue a quantum limited, high resolution, dynamic x-ray detector based on a CMOS sensor with 50 μm pixel size. For the proposed MAF-CMOS, the estimated charge collected within the full exposure range was found to be within the estimated full well capacity of the pixels. Expected instrumentation noise for the proposed detector was estimated to be 50-1,300 electrons. Adding a gain stage such as a light image intensifier would minimize the effect of the estimated instrumentation noise on total image noise but may not be necessary to ensure quantum limited detector operation at low exposure levels. A recursive temporal filter may decrease the effective total noise by 2 to 3 times, allowing for the improved signal to noise ratios at the lowest estimated exposures despite consequent loss in temporal resolution. This work can serve as a guide for further development of dynamic x-ray imaging prototypes or improvements for existing dynamic x-ray imaging systems.

Study of the material of the ATLAS inner detector for Run 2 of the LHC

DOE PAGES

Aaboud, M.; Aad, G.; Abbott, B.; ...

2017-12-07

The ATLAS inner detector comprises three different sub-detectors: the pixel detector, the silicon strip tracker, and the transition-radiation drift-tube tracker. The Insertable B-Layer, a new innermost pixel layer, was installed during the shutdown period in 2014, together with modifications to the layout of the cables and support structures of the existing pixel detector. The material in the inner detector is studied with several methods, using a low-luminosity √s=13 TeV pp collision sample corresponding to around 2.0 nb -1 collected in 2015 with the ATLAS experiment at the LHC. In this paper, the material within the innermost barrel region is studiedmore » using reconstructed hadronic interaction and photon conversion vertices. For the forward rapidity region, the material is probed by a measurement of the efficiency with which single tracks reconstructed from pixel detector hits alone can be extended with hits on the track in the strip layers. The results of these studies have been taken into account in an improved description of the material in the ATLAS inner detector simulation, resulting in a reduction in the uncertainties associated with the charged-particle reconstruction efficiency determined from simulation.« less

Study of the material of the ATLAS inner detector for Run 2 of the LHC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aaboud, M.; Aad, G.; Abbott, B.

The ATLAS inner detector comprises three different sub-detectors: the pixel detector, the silicon strip tracker, and the transition-radiation drift-tube tracker. The Insertable B-Layer, a new innermost pixel layer, was installed during the shutdown period in 2014, together with modifications to the layout of the cables and support structures of the existing pixel detector. The material in the inner detector is studied with several methods, using a low-luminosity √s=13 TeV pp collision sample corresponding to around 2.0 nb -1 collected in 2015 with the ATLAS experiment at the LHC. In this paper, the material within the innermost barrel region is studiedmore » using reconstructed hadronic interaction and photon conversion vertices. For the forward rapidity region, the material is probed by a measurement of the efficiency with which single tracks reconstructed from pixel detector hits alone can be extended with hits on the track in the strip layers. The results of these studies have been taken into account in an improved description of the material in the ATLAS inner detector simulation, resulting in a reduction in the uncertainties associated with the charged-particle reconstruction efficiency determined from simulation.« less

Study of the material of the ATLAS inner detector for Run 2 of the LHC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aaboud, M.; Aad, G.; Abbott, B.

The ATLAS inner detector comprises three different sub-detectors: the pixel detector, the silicon strip tracker, and the transition-radiation drift-tube tracker. The Insertable B-Layer, a new innermost pixel layer, was installed during the shutdown period in 2014, together with modifications to the layout of the cables and support structures of the existing pixel detector. The material in the inner detector is studied with several methods, using a low-luminosity √s = 13 TeV pp collision sample corresponding to around 2.0 nb -1 collected in 2015 with the ATLAS experiment at the LHC. In this paper, the material within the innermost barrel regionmore » is studied using reconstructed hadronic interaction and photon conversion vertices. For the forward rapidity region, the material is probed by a measurement of the efficiency with which single tracks reconstructed from pixel detector hits alone can be extended with hits on the track in the strip layers. The results of these studies have been taken into account in an improved description of the material in the ATLAS inner detector simulation, resulting in a reduction in the uncertainties associated with the charged-particle reconstruction efficiency determined from simulation.« less

Study of the material of the ATLAS inner detector for Run 2 of the LHC

NASA Astrophysics Data System (ADS)

Aaboud, M.; Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Abeloos, B.; Abidi, S. H.; AbouZeid, O. S.; Abraham, N. L.; Abramowicz, H.; Abreu, H.; Abreu, R.; Abulaiti, Y.; Acharya, B. S.; Adachi, S.; Adamczyk, L.; Adelman, J.; Adersberger, M.; Adye, T.; Affolder, A. A.; Agatonovic-Jovin, T.; Agheorghiesei, C.; Aguilar-Saavedra, J. A.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Akatsuka, S.; Akerstedt, H.; Åkesson, T. P. A.; Akilli, E.; Akimov, A. V.; Alberghi, G. L.; Albert, J.; Albicocco, P.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexopoulos, T.; Alhroob, M.; Ali, B.; Aliev, M.; Alimonti, G.; Alison, J.; Alkire, S. P.; Allbrooke, B. M. M.; Allen, B. W.; Allport, P. P.; Aloisio, A.; Alonso, A.; Alonso, F.; Alpigiani, C.; Alshehri, A. A.; Alstaty, M.; Alvarez Gonzalez, B.; Álvarez Piqueras, D.; Alviggi, M. G.; Amadio, B. T.; Amaral Coutinho, Y.; Amelung, C.; Amidei, D.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, J. K.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Angelidakis, S.; Angelozzi, I.; Angerami, A.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antel, C.; Antonelli, M.; Antonov, A.; Antrim, D. J.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Arabidze, G.; Arai, Y.; Araque, J. P.; Araujo Ferraz, V.; Arce, A. T. H.; Ardell, R. E.; Arduh, F. A.; Arguin, J.-F.; Argyropoulos, S.; Arik, M.; Armbruster, A. J.; Armitage, L. J.; Arnaez, O.; Arnold, H.; Arratia, M.; Arslan, O.; Artamonov, A.; Artoni, G.; Artz, S.; Asai, S.; Asbah, N.; Ashkenazi, A.; Asquith, L.; Assamagan, K.; Astalos, R.; Atkinson, M.; Atlay, N. B.; Augsten, K.; Avolio, G.; Axen, B.; Ayoub, M. K.; Azuelos, G.; Baas, A. E.; Baca, M. J.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Bagnaia, P.; Bahrasemani, H.; Baines, J. T.; Bajic, M.; Baker, O. K.; Baldin, E. M.; Balek, P.; Balli, F.; Balunas, W. K.; Banas, E.; Banerjee, Sw.; Bannoura, A. A. E.; Barak, L.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisits, M.-S.; Barkeloo, J. T.; Barklow, T.; Barlow, N.; Barnes, S. L.; Barnett, B. M.; Barnett, R. M.; Barnovska-Blenessy, Z.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barranco Navarro, L.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartos, P.; Basalaev, A.; Bassalat, A.; Bates, R. L.; Batista, S. J.; Batley, J. R.; Battaglia, M.; Bauce, M.; Bauer, F.; Bawa, H. S.; Beacham, J. B.; Beattie, M. D.; Beau, T.; Beauchemin, P. H.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, M.; Beckingham, M.; Becot, C.; Beddall, A. J.; Beddall, A.; Bednyakov, V. A.; Bedognetti, M.; Bee, C. P.; Beermann, T. A.; Begalli, M.; Begel, M.; Behr, J. K.; Bell, A. S.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belotskiy, K.; Beltramello, O.; Belyaev, N. L.; Benary, O.; Benchekroun, D.; Bender, M.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez, J.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Bentvelsen, S.; Beresford, L.; Beretta, M.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Beringer, J.; Berlendis, S.; Bernard, N. R.; Bernardi, G.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertoli, G.; Bertolucci, F.; Bertram, I. A.; Bertsche, C.; Bertsche, D.; Besjes, G. J.; Bessidskaia Bylund, O.; Bessner, M.; Besson, N.; Betancourt, C.; Bethani, A.; Bethke, S.; Bevan, A. J.; Beyer, J.; Bianchi, R. M.; Biebel, O.; Biedermann, D.; Bielski, R.; Biesuz, N. V.; Biglietti, M.; Bilbao De Mendizabal, J.; Billoud, T. R. V.; Bilokon, H.; Bindi, M.; Bingul, A.; Bini, C.; Biondi, S.; Bisanz, T.; Bittrich, C.; Bjergaard, D. M.; Black, C. W.; Black, J. E.; Black, K. M.; Blair, R. E.; Blazek, T.; Bloch, I.; Blocker, C.; Blue, A.; Blum, W.; Blumenschein, U.; Blunier, S.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Bock, C.; Boehler, M.; Boerner, D.; Bogavac, D.; Bogdanchikov, A. G.; Bohm, C.; Boisvert, V.; Bokan, P.; Bold, T.; Boldyrev, A. S.; Bolz, A. E.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Bortfeldt, J.; Bortoletto, D.; Bortolotto, V.; Boscherini, D.; Bosman, M.; Bossio Sola, J. D.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Boutle, S. K.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bracinik, J.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Breaden Madden, W. D.; Brendlinger, K.; Brennan, A. J.; Brenner, L.; Brenner, R.; Bressler, S.; Briglin, D. L.; Bristow, T. M.; Britton, D.; Britzger, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Broughton, J. H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruni, A.; Bruni, G.; Bruni, L. S.; Brunt, BH; Bruschi, M.; Bruscino, N.; Bryant, P.; Bryngemark, L.; Buanes, T.; Buat, Q.; Buchholz, P.; Buckley, A. G.; Budagov, I. A.; Buehrer, F.; Bugge, M. K.; Bulekov, O.; Bullock, D.; Burch, T. J.; Burckhart, H.; Burdin, S.; Burgard, C. D.; Burger, A. M.; Burghgrave, B.; Burka, K.; Burke, S.; Burmeister, I.; Burr, J. T. P.; Busato, E.; Büscher, D.; Büscher, V.; Bussey, P.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Butti, P.; Buttinger, W.; Buzatu, A.; Buzykaev, A. R.; Cabrera Urbán, S.; Caforio, D.; Cairo, V. M.; Cakir, O.; Calace, N.; Calafiura, P.; Calandri, A.; Calderini, G.; Calfayan, P.; Callea, G.; Caloba, L. P.; Calvente Lopez, S.; Calvet, D.; Calvet, S.; Calvet, T. P.; Camacho Toro, R.; Camarda, S.; Camarri, P.; Cameron, D.; Caminal Armadans, R.; Camincher, C.; Campana, S.; Campanelli, M.; Camplani, A.; Campoverde, A.; Canale, V.; Cano Bret, M.; Cantero, J.; Cao, T.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capua, M.; Carbone, R. M.; Cardarelli, R.; Cardillo, F.; Carli, I.; Carli, T.; Carlino, G.; Carlson, B. T.; Carminati, L.; Carney, R. M. D.; Caron, S.; Carquin, E.; Carrá, S.; Carrillo-Montoya, G. D.; Carvalho, J.; Casadei, D.; Casado, M. P.; Casolino, M.; Casper, D. W.; Castelijn, R.; Castillo Gimenez, V.; Castro, N. F.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Caudron, J.; Cavaliere, V.; Cavallaro, E.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Celebi, E.; Ceradini, F.; Cerda Alberich, L.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cervelli, A.; Cetin, S. A.; Chafaq, A.; Chakraborty, D.; Chan, S. K.; Chan, W. S.; Chan, Y. L.; Chang, P.; Chapman, J. D.; Charlton, D. G.; Chau, C. C.; Chavez Barajas, C. A.; Che, S.; Cheatham, S.; Chegwidden, A.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, S.; Chen, S.; Chen, X.; Chen, Y.; Cheng, H. C.; Cheng, H. J.; Cheplakov, A.; Cheremushkina, E.; Cherkaoui El Moursli, R.; Chernyatin, V.; Cheu, E.; Cheung, K.; Chevalier, L.; Chiarella, V.; Chiarelli, G.; Chiodini, G.; Chisholm, A. S.; Chitan, A.; Chiu, Y. H.; Chizhov, M. V.; Choi, K.; Chomont, A. R.; Chouridou, S.; Christodoulou, V.; Chromek-Burckhart, D.; Chu, M. C.; Chudoba, J.; Chuinard, A. J.; Chwastowski, J. J.; Chytka, L.; Ciftci, A. K.; Cinca, D.; Cindro, V.; Cioara, I. A.; Ciocca, C.; Ciocio, A.; Cirotto, F.; Citron, Z. H.; Citterio, M.; Ciubancan, M.; Clark, A.; Clark, B. L.; Clark, M. R.; Clark, P. J.; Clarke, R. N.; Clement, C.; Coadou, Y.; Cobal, M.; Coccaro, A.; Cochran, J.; Colasurdo, L.; Cole, B.; Colijn, A. P.; Collot, J.; Colombo, T.; Conde Muiño, P.; Coniavitis, E.; Connell, S. H.; Connelly, I. A.; Constantinescu, S.; Conti, G.; Conventi, F.; Cooke, M.; Cooper-Sarkar, A. M.; Cormier, F.; Cormier, K. J. R.; Corradi, M.; Corriveau, F.; Cortes-Gonzalez, A.; Cortiana, G.; Costa, G.; Costa, M. J.; Costanzo, D.; Cottin, G.; Cowan, G.; Cox, B. E.; Cranmer, K.; Crawley, S. J.; Creager, R. A.; Cree, G.; Crépé-Renaudin, S.; Crescioli, F.; Cribbs, W. A.; Cristinziani, M.; Croft, V.; Crosetti, G.; Cueto, A.; Cuhadar Donszelmann, T.; Cukierman, A. R.; Cummings, J.; Curatolo, M.; Cúth, J.; Czirr, H.; Czodrowski, P.; D'amen, G.; D'Auria, S.; D'eramo, L.; D'Onofrio, M.; Da Cunha Sargedas De Sousa, M. J.; Da Via, C.; Dabrowski, W.; Dado, T.; Dai, T.; Dale, O.; Dallaire, F.; Dallapiccola, C.; Dam, M.; Dandoy, J. R.; Daneri, M. F.; Dang, N. P.; Daniells, A. C.; Dann, N. S.; Danninger, M.; Dano Hoffmann, M.; Dao, V.; Darbo, G.; Darmora, S.; Dassoulas, J.; Dattagupta, A.; Daubney, T.; Davey, W.; David, C.; Davidek, T.; Davies, M.; Davis, D. R.; Davison, P.; Dawe, E.; Dawson, I.; De, K.; de Asmundis, R.; De Benedetti, A.; De Castro, S.; De Cecco, S.; De Groot, N.; de Jong, P.; De la Torre, H.; De Lorenzi, F.; De Maria, A.; De Pedis, D.; De Salvo, A.; De Sanctis, U.; De Santo, A.; De Vasconcelos Corga, K.; De Vivie De Regie, J. B.; Dearnaley, W. J.; Debbe, R.; Debenedetti, C.; Dedovich, D. V.; Dehghanian, N.; Deigaard, I.; Del Gaudio, M.; Del Peso, J.; Del Prete, T.; Delgove, D.; Deliot, F.; Delitzsch, C. M.; Dell'Acqua, A.; Dell'Asta, L.; Dell'Orso, M.; Della Pietra, M.; della Volpe, D.; Delmastro, M.; Delporte, C.; Delsart, P. A.; DeMarco, D. A.; Demers, S.; Demichev, M.; Demilly, A.; Denisov, S. P.; Denysiuk, D.; Derendarz, D.; Derkaoui, J. E.; Derue, F.; Dervan, P.; Desch, K.; Deterre, C.; Dette, K.; Devesa, M. R.; Deviveiros, P. O.; Dewhurst, A.; Dhaliwal, S.; Di Bello, F. A.; Di Ciaccio, A.; Di Ciaccio, L.; Di Clemente, W. K.; Di Donato, C.; Di Girolamo, A.; Di Girolamo, B.; Di Micco, B.; Di Nardo, R.; Di Petrillo, K. F.; Di Simone, A.; Di Sipio, R.; Di Valentino, D.; Diaconu, C.; Diamond, M.; Dias, F. A.; Diaz, M. A.; Diehl, E. B.; Dietrich, J.; Díez Cornell, S.; Dimitrievska, A.; Dingfelder, J.; Dita, P.; Dita, S.; Dittus, F.; Djama, F.; Djobava, T.; Djuvsland, J. I.; do Vale, M. A. B.; Dobos, D.; Dobre, M.; Doglioni, C.; Dolejsi, J.; Dolezal, Z.; Donadelli, M.; Donati, S.; Dondero, P.; Donini, J.; Dopke, J.; Doria, A.; Dova, M. T.; Doyle, A. T.; Drechsler, E.; Dris, M.; Du, Y.; Duarte-Campderros, J.; Dubreuil, A.; Duchovni, E.; Duckeck, G.; Ducourthial, A.; Ducu, O. A.; Duda, D.; Dudarev, A.; Dudder, A. Chr.; Duffield, E. M.; Duflot, L.; Dührssen, M.; Dumancic, M.; Dumitriu, A. E.; Duncan, A. K.; Dunford, M.; Duran Yildiz, H.; Düren, M.; Durglishvili, A.; Duschinger, D.; Dutta, B.; Dyndal, M.; Dziedzic, B. S.; Eckardt, C.; Ecker, K. M.; Edgar, R. C.; Eifert, T.; Eigen, G.; Einsweiler, K.; Ekelof, T.; El Kacimi, M.; El Kosseifi, R.; Ellajosyula, V.; Ellert, M.; Elles, S.; Ellinghaus, F.; Elliot, A. A.; Ellis, N.; Elmsheuser, J.; Elsing, M.; Emeliyanov, D.; Enari, Y.; Endner, O. C.; Ennis, J. S.; Erdmann, J.; Ereditato, A.; Ernis, G.; Ernst, M.; Errede, S.; Escalier, M.; Escobar, C.; Esposito, B.; Estrada Pastor, O.; Etienvre, A. I.; Etzion, E.; Evans, H.; Ezhilov, A.; Ezzi, M.; Fabbri, F.; Fabbri, L.; Facini, G.; Fakhrutdinov, R. M.; Falciano, S.; Falla, R. J.; Faltova, J.; Fang, Y.; Fanti, M.; Farbin, A.; Farilla, A.; Farina, C.; Farina, E. M.; Farooque, T.; Farrell, S.; Farrington, S. M.; Farthouat, P.; Fassi, F.; Fassnacht, P.; Fassouliotis, D.; Faucci Giannelli, M.; Favareto, A.; Fawcett, W. J.; Fayard, L.; Fedin, O. L.; Fedorko, W.; Feigl, S.; Feligioni, L.; Feng, C.; Feng, E. J.; Feng, H.; Fenton, M. J.; Fenyuk, A. 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F.; Narayan, R.; Narrias Villar, D. I.; Naryshkin, I.; Naumann, T.; Navarro, G.; Nayyar, R.; Neal, H. A.; Nechaeva, P. Yu.; Neep, T. J.; Negri, A.; Negrini, M.; Nektarijevic, S.; Nellist, C.; Nelson, A.; Nelson, M. E.; Nemecek, S.; Nemethy, P.; Nessi, M.; Neubauer, M. S.; Neumann, M.; Newman, P. R.; Ng, T. Y.; Nguyen Manh, T.; Nickerson, R. B.; Nicolaidou, R.; Nielsen, J.; Nikolaenko, V.; Nikolic-Audit, I.; Nikolopoulos, K.; Nilsen, J. K.; Nilsson, P.; Ninomiya, Y.; Nisati, A.; Nishu, N.; Nisius, R.; Nitsche, I.; Nitta, T.; Nobe, T.; Noguchi, Y.; Nomachi, M.; Nomidis, I.; Nomura, M. A.; Nooney, T.; Nordberg, M.; Norjoharuddeen, N.; Novgorodova, O.; Nowak, S.; Nozaki, M.; Nozka, L.; Ntekas, K.; Nurse, E.; Nuti, F.; O'connor, K.; O'Neil, D. C.; O'Rourke, A. A.; O'Shea, V.; Oakham, F. G.; Oberlack, H.; Obermann, T.; Ocariz, J.; Ochi, A.; Ochoa, I.; Ochoa-Ricoux, J. P.; Oda, S.; Odaka, S.; Ogren, H.; Oh, A.; Oh, S. H.; Ohm, C. C.; Ohman, H.; Oide, H.; Okawa, H.; Okumura, Y.; Okuyama, T.; Olariu, A.; Oleiro Seabra, L. F.; Olivares Pino, S. A.; Oliveira Damazio, D.; Olszewski, A.; Olszowska, J.; Onofre, A.; Onogi, K.; Onyisi, P. U. E.; Oreglia, M. J.; Oren, Y.; Orestano, D.; Orlando, N.; Orr, R. S.; Osculati, B.; Ospanov, R.; Garzon, G. Otero y.; Otono, H.; Ouchrif, M.; Ould-Saada, F.; Ouraou, A.; Oussoren, K. P.; Ouyang, Q.; Owen, M.; Owen, R. E.; Ozcan, V. E.; Ozturk, N.; Pachal, K.; Pacheco Pages, A.; Pacheco Rodriguez, L.; Padilla Aranda, C.; Pagan Griso, S.; Paganini, M.; Paige, F.; Palacino, G.; Palazzo, S.; Palestini, S.; Palka, M.; Pallin, D.; Panagiotopoulou, E. St.; Panagoulias, I.; Pandini, C. E.; Panduro Vazquez, J. G.; Pani, P.; Panitkin, S.; Pantea, D.; Paolozzi, L.; Papadopoulou, Th. D.; Papageorgiou, K.; Paramonov, A.; Paredes Hernandez, D.; Parker, A. J.; Parker, M. A.; Parker, K. A.; Parodi, F.; Parsons, J. A.; Parzefall, U.; Pascuzzi, V. R.; Pasner, J. M.; Pasqualucci, E.; Passaggio, S.; Pastore, Fr.; Pataraia, S.; Pater, J. R.; Pauly, T.; Pearson, B.; Pedraza Lopez, S.; Pedro, R.; Peleganchuk, S. V.; Penc, O.; Peng, C.; Peng, H.; Penwell, J.; Peralva, B. S.; Perego, M. M.; Perepelitsa, D. V.; Peri, F.; Perini, L.; Pernegger, H.; Perrella, S.; Peschke, R.; Peshekhonov, V. D.; Peters, K.; Peters, R. F. Y.; Petersen, B. A.; Petersen, T. C.; Petit, E.; Petridis, A.; Petridou, C.; Petroff, P.; Petrolo, E.; Petrov, M.; Petrucci, F.; Pettersson, N. E.; Peyaud, A.; Pezoa, R.; Phillips, F. H.; Phillips, P. W.; Piacquadio, G.; Pianori, E.; Picazio, A.; Piccaro, E.; Pickering, M. A.; Piegaia, R.; Pilcher, J. E.; Pilkington, A. D.; Pin, A. W. J.; Pinamonti, M.; Pinfold, J. L.; Pirumov, H.; Pitt, M.; Plazak, L.; Pleier, M.-A.; Pleskot, V.; Plotnikova, E.; Pluth, D.; Podberezko, P.; Poettgen, R.; Poggi, R.; Poggioli, L.; Pohl, D.; Polesello, G.; Poley, A.; Policicchio, A.; Polifka, R.; Polini, A.; Pollard, C. S.; Polychronakos, V.; Pommès, K.; Ponomarenko, D.; Pontecorvo, L.; Pope, B. G.; Popeneciu, G. A.; Poppleton, A.; Pospisil, S.; Potamianos, K.; Potrap, I. N.; Potter, C. J.; Poulard, G.; Poulsen, T.; Poveda, J.; Pozo Astigarraga, M. E.; Pralavorio, P.; Pranko, A.; Prell, S.; Price, D.; Price, L. E.; Primavera, M.; Prince, S.; Proklova, N.; Prokofiev, K.; Prokoshin, F.; Protopopescu, S.; Proudfoot, J.; Przybycien, M.; Puri, A.; Puzo, P.; Qian, J.; Qin, G.; Qin, Y.; Quadt, A.; Queitsch-Maitland, M.; Quilty, D.; Raddum, S.; Radeka, V.; Radescu, V.; Radhakrishnan, S. K.; Radloff, P.; Rados, P.; Ragusa, F.; Rahal, G.; Raine, J. A.; Rajagopalan, S.; Rangel-Smith, C.; Rashid, T.; Raspopov, S.; Ratti, M. G.; Rauch, D. M.; Rauscher, F.; Rave, S.; Ravinovich, I.; Rawling, J. H.; Raymond, M.; Read, A. L.; Readioff, N. P.; Reale, M.; Rebuzzi, D. M.; Redelbach, A.; Redlinger, G.; Reece, R.; Reed, R. G.; Reeves, K.; Rehnisch, L.; Reichert, J.; Reiss, A.; Rembser, C.; Ren, H.; Rescigno, M.; Resconi, S.; Resseguie, E. D.; Rettie, S.; Reynolds, E.; Rezanova, O. L.; Reznicek, P.; Rezvani, R.; Richter, R.; Richter, S.; Richter-Was, E.; Ricken, O.; Ridel, M.; Rieck, P.; Riegel, C. J.; Rieger, J.; Rifki, O.; Rijssenbeek, M.; Rimoldi, A.; Rimoldi, M.; Rinaldi, L.; Ripellino, G.; Ristić, B.; Ritsch, E.; Riu, I.; Rizatdinova, F.; Rizvi, E.; Rizzi, C.; Roberts, R. T.; Robertson, S. H.; Robichaud-Veronneau, A.; Robinson, D.; Robinson, J. E. M.; Robson, A.; Rocco, E.; Roda, C.; Rodina, Y.; Rodriguez Bosca, S.; Rodriguez Perez, A.; Rodriguez Rodriguez, D.; Roe, S.; Rogan, C. S.; RØhne, O.; Roloff, J.; Romaniouk, A.; Romano, M.; Romano Saez, S. M.; Romero Adam, E.; Rompotis, N.; Ronzani, M.; Roos, L.; Rosati, S.; Rosbach, K.; Rose, P.; Rosien, N.-A.; Rossi, E.; Rossi, L. P.; Rosten, J. H. N.; Rosten, R.; Rotaru, M.; Roth, I.; Rothberg, J.; Rousseau, D.; Rozanov, A.; Rozen, Y.; Ruan, X.; Rubbo, F.; Rühr, F.; Ruiz-Martinez, A.; Rurikova, Z.; Rusakovich, N. A.; Russell, H. L.; Rutherfoord, J. P.; Ruthmann, N.; Ryabov, Y. F.; Rybar, M.; Rybkin, G.; Ryu, S.; Ryzhov, A.; Rzehorz, G. F.; Saavedra, A. F.; Sabato, G.; Sacerdoti, S.; Sadrozinski, H. F.-W.; Sadykov, R.; Safai Tehrani, F.; Saha, P.; Sahinsoy, M.; Saimpert, M.; Saito, M.; Saito, T.; Sakamoto, H.; Sakurai, Y.; Salamanna, G.; Salazar Loyola, J. E.; Salek, D.; Sales De Bruin, P. H.; Salihagic, D.; Salnikov, A.; Salt, J.; Salvatore, D.; Salvatore, F.; Salvucci, A.; Salzburger, A.; Sammel, D.; Sampsonidis, D.; Sampsonidou, D.; Sánchez, J.; Sanchez Martinez, V.; Sanchez Pineda, A.; Sandaker, H.; Sandbach, R. L.; Sander, C. O.; Sandhoff, M.; Sandoval, C.; Sankey, D. P. C.; Sannino, M.; Sano, Y.; Sansoni, A.; Santoni, C.; Santonico, R.; Santos, H.; Santoyo Castillo, I.; Sapronov, A.; Saraiva, J. G.; Sarrazin, B.; Sasaki, O.; Sato, K.; Sauvan, E.; Savage, G.; Savard, P.; Savic, N.; Sawyer, C.; Sawyer, L.; Saxon, J.; Sbarra, C.; Sbrizzi, A.; Scanlon, T.; Scannicchio, D. A.; Scarcella, M.; Scarfone, V.; Schaarschmidt, J.; Schacht, P.; Schachtner, B. M.; Schaefer, D.; Schaefer, L.; Schaefer, R.; Schaeffer, J.; Schaepe, S.; Schaetzel, S.; Schäfer, U.; Schaffer, A. C.; Schaile, D.; Schamberger, R. D.; Scharf, V.; Schegelsky, V. A.; Scheirich, D.; Schernau, M.; Schiavi, C.; Schier, S.; Schildgen, L. K.; Schillo, C.; Schioppa, M.; Schlenker, S.; Schmidt-Sommerfeld, K. R.; Schmieden, K.; Schmitt, C.; Schmitt, S.; Schmitz, S.; Schnoor, U.; Schoeffel, L.; Schoening, A.; Schoenrock, B. D.; Schopf, E.; Schott, M.; Schouwenberg, J. F. P.; Schovancova, J.; Schramm, S.; Schuh, N.; Schulte, A.; Schultens, M. J.; Schultz-Coulon, H.-C.; Schulz, H.; Schumacher, M.; Schumm, B. A.; Schune, Ph.; Schwartzman, A.; Schwarz, T. A.; Schweiger, H.; Schwemling, Ph.; Schwienhorst, R.; Schwindling, J.; Sciandra, A.; Sciolla, G.; Scuri, F.; Scutti, F.; Searcy, J.; Seema, P.; Seidel, S. C.; Seiden, A.; Seixas, J. M.; Sekhniaidze, G.; Sekhon, K.; Sekula, S. J.; Semprini-Cesari, N.; Senkin, S.; Serfon, C.; Serin, L.; Serkin, L.; Sessa, M.; Seuster, R.; Severini, H.; Sfiligoj, T.; Sforza, F.; Sfyrla, A.; Shabalina, E.; Shaikh, N. W.; Shan, L. Y.; Shang, R.; Shank, J. T.; Shapiro, M.; Shatalov, P. B.; Shaw, K.; Shaw, S. M.; Shcherbakova, A.; Shehu, C. Y.; Shen, Y.; Sherafati, N.; Sherwood, P.; Shi, L.; Shimizu, S.; Shimmin, C. O.; Shimojima, M.; Shipsey, I. P. J.; Shirabe, S.; Shiyakova, M.; Shlomi, J.; Shmeleva, A.; Shoaleh Saadi, D.; Shochet, M. J.; Shojaii, S.; Shope, D. R.; Shrestha, S.; Shulga, E.; Shupe, M. A.; Sicho, P.; Sickles, A. M.; Sidebo, P. E.; Sideras Haddad, E.; Sidiropoulou, O.; Sidoti, A.; Siegert, F.; Sijacki, Dj.; Silva, J.; Silverstein, S. B.; Simak, V.; Simic, Lj.; Simion, S.; Simioni, E.; Simmons, B.; Simon, M.; Sinervo, P.; Sinev, N. B.; Sioli, M.; Siragusa, G.; Siral, I.; Sivoklokov, S. Yu.; Sjölin, J.; Skinner, M. B.; Skubic, P.; Slater, M.; Slavicek, T.; Slawinska, M.; Sliwa, K.; Slovak, R.; Smakhtin, V.; Smart, B. H.; Smiesko, J.; Smirnov, N.; Smirnov, S. Yu.; Smirnov, Y.; Smirnova, L. N.; Smirnova, O.; Smith, J. W.; Smith, M. N. K.; Smith, R. W.; Smizanska, M.; Smolek, K.; Snesarev, A. A.; Snyder, I. M.; Snyder, S.; Sobie, R.; Socher, F.; Soffer, A.; Soh, D. A.; Sokhrannyi, G.; Solans Sanchez, C. A.; Solar, M.; Soldatov, E. Yu.; Soldevila, U.; Solodkov, A. A.; Soloshenko, A.; Solovyanov, O. V.; Solovyev, V.; Sommer, P.; Son, H.; Sopczak, A.; Sosa, D.; Sotiropoulou, C. L.; Soualah, R.; Soukharev, A. M.; South, D.; Sowden, B. C.; Spagnolo, S.; Spalla, M.; Spangenberg, M.; Spanò, F.; Sperlich, D.; Spettel, F.; Spieker, T. M.; Spighi, R.; Spigo, G.; Spiller, L. A.; Spousta, M.; St. Denis, R. D.; Stabile, A.; Stamen, R.; Stamm, S.; Stanecka, E.; Stanek, R. W.; Stanescu, C.; Stanitzki, M. M.; Stapf, B. S.; Stapnes, S.; Starchenko, E. A.; Stark, G. H.; Stark, J.; Stark, S. H.; Staroba, P.; Starovoitov, P.; Stärz, S.; Staszewski, R.; Steinberg, P.; Stelzer, B.; Stelzer, H. J.; Stelzer-Chilton, O.; Stenzel, H.; Stewart, G. A.; Stockton, M. C.; Stoebe, M.; Stoicea, G.; Stolte, P.; Stonjek, S.; Stradling, A. R.; Straessner, A.; Stramaglia, M. E.; Strandberg, J.; Strandberg, S.; Strauss, M.; Strizenec, P.; Ströhmer, R.; Strom, D. M.; Stroynowski, R.; Strubig, A.; Stucci, S. A.; Stugu, B.; Styles, N. A.; Su, D.; Su, J.; Suchek, S.; Sugaya, Y.; Suk, M.; Sulin, V. V.; Sultan, DMS; Sultansoy, S.; Sumida, T.; Sun, S.; Sun, X.; Suruliz, K.; Suster, C. J. E.; Sutton, M. R.; Suzuki, S.; Svatos, M.; Swiatlowski, M.; Swift, S. P.; Sykora, I.; Sykora, T.; Ta, D.; Tackmann, K.; Taenzer, J.; Taffard, A.; Tafirout, R.; Taiblum, N.; Takai, H.; Takashima, R.; Takasugi, E. H.; Takeshita, T.; Takubo, Y.; Talby, M.; Talyshev, A. A.; Tanaka, J.; Tanaka, M.; Tanaka, R.; Tanaka, S.; Tanioka, R.; Tannenwald, B. B.; Tapia Araya, S.; Tapprogge, S.; Tarem, S.; Tartarelli, G. F.; Tas, P.; Tasevsky, M.; Tashiro, T.; Tassi, E.; Tavares Delgado, A.; Tayalati, Y.; Taylor, A. C.; Taylor, G. N.; Taylor, P. T. E.; Taylor, W.; Teixeira-Dias, P.; Temple, D.; Ten Kate, H.; Teng, P. K.; Teoh, J. J.; Tepel, F.; Terada, S.; Terashi, K.; Terron, J.; Terzo, S.; Testa, M.; Teuscher, R. J.; Theveneaux-Pelzer, T.; Thomas, J. P.; Thomas-Wilsker, J.; Thompson, P. D.; Thompson, A. S.; Thomsen, L. A.; Thomson, E.; Tibbetts, M. J.; Ticse Torres, R. E.; Tikhomirov, V. O.; Tikhonov, Yu. A.; Timoshenko, S.; Tipton, P.; Tisserant, S.; Todome, K.; Todorova-Nova, S.; Tojo, J.; Tokár, S.; Tokushuku, K.; Tolley, E.; Tomlinson, L.; Tomoto, M.; Tompkins, L.; Toms, K.; Tong, B.; Tornambe, P.; Torrence, E.; Torres, H.; Torró Pastor, E.; Toth, J.; Touchard, F.; Tovey, D. R.; Treado, C. J.; Trefzger, T.; Tresoldi, F.; Tricoli, A.; Trigger, I. M.; Trincaz-Duvoid, S.; Tripiana, M. F.; Trischuk, W.; Trocmé, B.; Trofymov, A.; Troncon, C.; Trottier-McDonald, M.; Trovatelli, M.; Truong, L.; Trzebinski, M.; Trzupek, A.; Tsang, K. W.; Tseng, J. C.-L.; Tsiareshka, P. V.; Tsipolitis, G.; Tsirintanis, N.; Tsiskaridze, S.; Tsiskaridze, V.; Tskhadadze, E. G.; Tsui, K. M.; Tsukerman, I. I.; Tsulaia, V.; Tsuno, S.; Tsybychev, D.; Tu, Y.; Tudorache, A.; Tudorache, V.; Tulbure, T. T.; Tuna, A. N.; Tupputi, S. A.; Turchikhin, S.; Turgeman, D.; Turk Cakir, I.; Turra, R.; Tuts, P. M.; Ucchielli, G.; Ueda, I.; Ughetto, M.; Ukegawa, F.; Unal, G.; Undrus, A.; Unel, G.; Ungaro, F. C.; Unno, Y.; Unverdorben, C.; Urban, J.; Urquijo, P.; Urrejola, P.; Usai, G.; Usui, J.; Vacavant, L.; Vacek, V.; Vachon, B.; Vaidya, A.; Valderanis, C.; Valdes Santurio, E.; Valentinetti, S.; Valero, A.; Valéry, L.; Valkar, S.; Vallier, A.; Valls Ferrer, J. A.; Van Den Wollenberg, W.; van der Graaf, H.; van Gemmeren, P.; Van Nieuwkoop, J.; van Vulpen, I.; van Woerden, M. C.; Vanadia, M.; Vandelli, W.; Vaniachine, A.; Vankov, P.; Vardanyan, G.; Vari, R.; Varnes, E. W.; Varni, C.; Varol, T.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vasquez, J. G.; Vasquez, G. A.; Vazeille, F.; Vazquez Schroeder, T.; Veatch, J.; Veeraraghavan, V.; Veloce, L. M.; Veloso, F.; Veneziano, S.; Ventura, A.; Venturi, M.; Venturi, N.; Venturini, A.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, A. T.; Vermeulen, J. C.; Vetterli, M. C.; Viaux Maira, N.; Viazlo, O.; Vichou, I.; Vickey, T.; Boeriu, O. E. Vickey; Viehhauser, G. H. A.; Viel, S.; Vigani, L.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinogradov, V. B.; Vishwakarma, A.; Vittori, C.; Vivarelli, I.; Vlachos, S.; Vogel, M.; Vokac, P.; Volpi, G.; von der Schmitt, H.; von Toerne, E.; Vorobel, V.; Vorobev, K.; Vos, M.; Voss, R.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vuillermet, R.; Vukotic, I.; Wagner, P.; Wagner, W.; Wagner-Kuhr, J.; Wahlberg, H.; Wahrmund, S.; Wakabayashi, J.; Walder, J.; Walker, R.; Walkowiak, W.; Wallangen, V.; Wang, C.; Wang, C.; Wang, F.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, Q.; Wang, R.; Wang, S. M.; Wang, T.; Wang, W.; Wang, W.; Wang, Z.; Wanotayaroj, C.; Warburton, A.; Ward, C. P.; Wardrope, D. R.; Washbrook, A.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, B. M.; Webb, A. F.; Webb, S.; Weber, M. S.; Weber, S. W.; Weber, S. A.; Webster, J. S.; Weidberg, A. R.; Weinert, B.; Weingarten, J.; Weirich, M.; Weiser, C.; Weits, H.; Wells, P. S.; Wenaus, T.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M. D.; Werner, P.; Wessels, M.; Whalen, K.; Whallon, N. L.; Wharton, A. M.; White, A. S.; White, A.; White, M. J.; White, R.; Whiteson, D.; Whitmore, B. W.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wiglesworth, C.; Wiik-Fuchs, L. A. M.; Wildauer, A.; Wilk, F.; Wilkens, H. G.; Williams, H. H.; Williams, S.; Willis, C.; Willocq, S.; Wilson, J. A.; Wingerter-Seez, I.; Winkels, E.; Winklmeier, F.; Winston, O. J.; Winter, B. T.; Wittgen, M.; Wobisch, M.; Wolf, T. M. H.; Wolff, R.; Wolter, M. W.; Wolters, H.; Wong, V. W. S.; Worm, S. D.; Wosiek, B. K.; Wotschack, J.; Wozniak, K. W.; Wu, M.; Wu, S. L.; Wu, X.; Wu, Y.; Wyatt, T. R.; Wynne, B. M.; Xella, S.; Xi, Z.; Xia, L.; Xu, D.; Xu, L.; Xu, T.; Yabsley, B.; Yacoob, S.; Yamaguchi, D.; Yamaguchi, Y.; Yamamoto, A.; Yamamoto, S.; Yamanaka, T.; Yamatani, M.; Yamauchi, K.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, H.; Yang, Y.; Yang, Z.; Yao, W.-M.; Yap, Y. C.; Yasu, Y.; Yatsenko, E.; Yau Wong, K. H.; Ye, J.; Ye, S.; Yeletskikh, I.; Yigitbasi, E.; Yildirim, E.; Yorita, K.; Yoshihara, K.; Young, C.; Young, C. J. S.; Yu, J.; Yu, J.; Yuen, S. P. Y.; Yusuff, I.; Zabinski, B.; Zacharis, G.; Zaidan, R.; Zaitsev, A. M.; Zakharchuk, N.; Zalieckas, J.; Zaman, A.; Zambito, S.; Zanzi, D.; Zeitnitz, C.; Zemaityte, G.; Zemla, A.; Zeng, J. C.; Zeng, Q.; Zenin, O.; Ženiš, T.; Zerwas, D.; Zhang, D.; Zhang, F.; Zhang, G.; Zhang, H.; Zhang, J.; Zhang, L.; Zhang, L.; Zhang, M.; Zhang, P.; Zhang, R.; Zhang, R.; Zhang, X.; Zhang, Y.; Zhang, Z.; Zhao, X.; Zhao, Y.; Zhao, Z.; Zhemchugov, A.; Zhou, B.; Zhou, C.; Zhou, L.; Zhou, M.; Zhou, M.; Zhou, N.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhukov, K.; Zibell, A.; Zieminska, D.; Zimine, N. I.; Zimmermann, C.; Zimmermann, S.; Zinonos, Z.; Zinser, M.; Ziolkowski, M.; Živković, L.; Zobernig, G.; Zoccoli, A.; Zou, R.; zur Nedden, M.; Zwalinski, L.

2017-12-01

The ATLAS inner detector comprises three different sub-detectors: the pixel detector, the silicon strip tracker, and the transition-radiation drift-tube tracker. The Insertable B-Layer, a new innermost pixel layer, was installed during the shutdown period in 2014, together with modifications to the layout of the cables and support structures of the existing pixel detector. The material in the inner detector is studied with several methods, using a low-luminosity √s=13 TeV pp collision sample corresponding to around 2.0 nb-1 collected in 2015 with the ATLAS experiment at the LHC. In this paper, the material within the innermost barrel region is studied using reconstructed hadronic interaction and photon conversion vertices. For the forward rapidity region, the material is probed by a measurement of the efficiency with which single tracks reconstructed from pixel detector hits alone can be extended with hits on the track in the strip layers. The results of these studies have been taken into account in an improved description of the material in the ATLAS inner detector simulation, resulting in a reduction in the uncertainties associated with the charged-particle reconstruction efficiency determined from simulation.

Study of the material of the ATLAS inner detector for Run 2 of the LHC

DOE PAGES

Aaboud, M.; Aad, G.; Abbott, B.; ...

2017-12-07

The ATLAS inner detector comprises three different sub-detectors: the pixel detector, the silicon strip tracker, and the transition-radiation drift-tube tracker. The Insertable B-Layer, a new innermost pixel layer, was installed during the shutdown period in 2014, together with modifications to the layout of the cables and support structures of the existing pixel detector. The material in the inner detector is studied with several methods, using a low-luminosity √s = 13 TeV pp collision sample corresponding to around 2.0 nb -1 collected in 2015 with the ATLAS experiment at the LHC. In this paper, the material within the innermost barrel regionmore » is studied using reconstructed hadronic interaction and photon conversion vertices. For the forward rapidity region, the material is probed by a measurement of the efficiency with which single tracks reconstructed from pixel detector hits alone can be extended with hits on the track in the strip layers. The results of these studies have been taken into account in an improved description of the material in the ATLAS inner detector simulation, resulting in a reduction in the uncertainties associated with the charged-particle reconstruction efficiency determined from simulation.« less

Using a pulsed laser beam to investigate the feasibility of sub-pixel position resolution with time-correlated transient signals in 3D pixelated CdZnTe detectors

DOE PAGES

Giraldo, L. Ocampo; Bolotnikov, A. E.; Camarda, G. S.; ...

2017-04-20

For this study, we evaluated the X-Y position resolution achievable in 3D pixelated detectors by processing the signal waveforms readout from neighboring pixels. In these measurements we used a focused light beam, down to 10 μm, generated by a ~1 mW pulsed laser (650 nm) to carry out raster scans over selected 3×3 pixel areas, while recording the charge signals from the 9 pixels and the cathode using two synchronized digital oscilloscopes.

Graphene metamaterial spatial light modulator for infrared single pixel imaging.

PubMed

Fan, Kebin; Suen, Jonathan Y; Padilla, Willie J

2017-10-16

High-resolution and hyperspectral imaging has long been a goal for multi-dimensional data fusion sensing applications - of interest for autonomous vehicles and environmental monitoring. In the long wave infrared regime this quest has been impeded by size, weight, power, and cost issues, especially as focal-plane array detector sizes increase. Here we propose and experimentally demonstrated a new approach based on a metamaterial graphene spatial light modulator (GSLM) for infrared single pixel imaging. A frequency-division multiplexing (FDM) imaging technique is designed and implemented, and relies entirely on the electronic reconfigurability of the GSLM. We compare our approach to the more common raster-scan method and directly show FDM image frame rates can be 64 times faster with no degradation of image quality. Our device and related imaging architecture are not restricted to the infrared regime, and may be scaled to other bands of the electromagnetic spectrum. The study presented here opens a new approach for fast and efficient single pixel imaging utilizing graphene metamaterials with novel acquisition strategies.

X-ray metrology of an array of active edge pixel sensors for use at synchrotron light sources

NASA Astrophysics Data System (ADS)

Plackett, R.; Arndt, K.; Bortoletto, D.; Horswell, I.; Lockwood, G.; Shipsey, I.; Tartoni, N.; Williams, S.

2018-01-01

We report on the production and testing of an array of active edge silicon sensors as a prototype of a large array. Four Medipix3RX.1 chips were bump bonded to four single chip sized Advacam active edge n-on-n sensors. These detectors were then mounted into a 2 by 2 array and tested on B16 at Diamond Light Source with an x-ray beam spot of 2um. The results from these tests, compared with optical metrology demonstrate that this type of sensor is sensitive to the physical edge of the silicon, with only a modest loss of efficiency in the final two rows of pixels. We present the efficiency maps recorded with the microfocus beam and a sample powder diffraction measurement. These results give confidence that this sensor technology can be used effectively in larger arrays of detectors at synchrotron light sources.

CANICA: The Cananea Near-Infrared Camera at the 2.1 m OAGH Telescope

NASA Astrophysics Data System (ADS)

Carrasco, L.; Hernández Utrera, O.; Vázquez, S.; Mayya, Y. D.; Carrasco, E.; Pedraza, J.; Castillo-Domínguez, E.; Escobedo, G.; Devaraj, R.; Luna, A.

2017-10-01

The Cananea near-infrared camera (CANICA) is an instrument commissioned at the 2.12 m telescope of the Guillermo Haro Astrophysical Observatory (OAGH) located in Cananea, Sonora, México. CANICA operates in the near-infrared at multiple bands including J(1.24 μm), H(1.63 μm) and K' (2.12 μm) broad-bands. CANICA in located at the Ritchey-Chrétien focal plane of the telescope, reimaging the f/12 beam into f/6 beam. The detector is a 1024 × 1024 HgCdTe HAWAII array of 18.5 μm pixel size, covering a field of view of 5.5 × 5.5 arcmin2, for a plate scale of 0.32 arcsec/pixel. The camera is enclosed in a cryostat, cooled with liquid nitrogen to 77 K. The cryostat contains the collimator, two 15-position filter wheels, single fixed reimaging optics and the detector.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jose, J. M.; Čermák, P.; Fajt, L.

The SPT collaboration has been investigating the applicability of pixel detectors in the detection of two neutrino double electron capture (2νEC/EC) in{sup 106}Cd. The collaboration has proposed a Silicon Pixel Telescope (SPT) where a pair of Si pixel detectors with enriched Cd foil in the middle forms the detection unit. The Pixel detector gives spatial information along with energy of the particle, thus helps to identify and remove the background signals. Four units of SPT prototype (using 0.5 and 1 mm Si sensors) were fabricated and installed in the LSM underground laboratory, France. Recent progress in the SPT experiment and preliminarymore » results from background measurements are presented.« less

Beam test results of the BTeV silicon pixel detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gabriele Chiodini et al.

2000-09-28

The authors have described the results of the BTeV silicon pixel detector beam test. The pixel detectors under test used samples of the first two generations of Fermilab pixel readout chips, FPIX0 and FPIX1, (indium bump-bonded to ATLAS sensor prototypes). The spatial resolution achieved using analog charge information is excellent for a large range of track inclination. The resolution is still very good using only 2-bit charge information. A relatively small dependence of the resolution on bias voltage is observed. The resolution is observed to depend dramatically on the discriminator threshold, and it deteriorates rapidly for threshold above 4000e{sup {minus}}.

Dual-gate photo thin-film transistor: a “smart” pixel for high- resolution and low-dose X-ray imaging

NASA Astrophysics Data System (ADS)

Wang, Kai; Ou, Hai; Chen, Jun

2015-06-01

Since its emergence a decade ago, amorphous silicon flat panel X-ray detector has established itself as a ubiquitous platform for an array of digital radiography modalities. The fundamental building block of a flat panel detector is called a pixel. In all current pixel architectures, sensing, storage, and readout are unanimously kept separate, inevitably compromising resolution by increasing pixel size. To address this issue, we hereby propose a “smart” pixel architecture where the aforementioned three components are combined in a single dual-gate photo thin-film transistor (TFT). In other words, the dual-gate photo TFT itself functions as a sensor, a storage capacitor, and a switch concurrently. Additionally, by harnessing the amplification effect of such a thin-film transistor, we for the first time created a single-transistor active pixel sensor. The proof-of-concept device had a W/L ratio of 250μm/20μm and was fabricated using a simple five-mask photolithography process, where a 130nm transparent ITO was used as the top photo gate, and a 200nm amorphous silicon as the absorbing channel layer. The preliminary results demonstrated that the photocurrent had been increased by four orders of magnitude due to light-induced threshold voltage shift in the sub-threshold region. The device sensitivity could be simply tuned by photo gate bias to specifically target low-level light detection. The dependence of threshold voltage on light illumination indicated that a dynamic range of at least 80dB could be achieved. The "smart" pixel technology holds tremendous promise for developing high-resolution and low-dose X-ray imaging and may potentially lower the cancer risk imposed by radiation, especially among paediatric patients.

Active Pixel Sensors: Are CCD's Dinosaurs?

NASA Technical Reports Server (NTRS)

Fossum, Eric R.

1993-01-01

Charge-coupled devices (CCD's) are presently the technology of choice for most imaging applications. In the 23 years since their invention in 1970, they have evolved to a sophisticated level of performance. However, as with all technologies, we can be certain that they will be supplanted someday. In this paper, the Active Pixel Sensor (APS) technology is explored as a possible successor to the CCD. An active pixel is defined as a detector array technology that has at least one active transistor within the pixel unit cell. The APS eliminates the need for nearly perfect charge transfer -- the Achilles' heel of CCDs. This perfect charge transfer makes CCD's radiation 'soft,' difficult to use under low light conditions, difficult to manufacture in large array sizes, difficult to integrate with on-chip electronics, difficult to use at low temperatures, difficult to use at high frame rates, and difficult to manufacture in non-silicon materials that extend wavelength response.

Quantitative comparison using Generalized Relative Object Detectability (G-ROD) metrics of an amorphous selenium detector with high resolution Microangiographic Fluoroscopes (MAF) and standard flat panel detectors (FPD).

PubMed

Russ, M; Shankar, A; Jain, A; Setlur Nagesh, S V; Ionita, C N; Scott, C; Karim, K S; Bednarek, D R; Rudin, S

2016-02-27

A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25 μ m pixel pitch, and 1000 μ m thick a-Se layer operating at 10V/ μ m bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-prewhitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal-spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide breakthrough abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices.

Quantitative comparison using generalized relative object detectability (G-ROD) metrics of an amorphous selenium detector with high resolution microangiographic fluoroscopes (MAF) and standard flat panel detectors (FPD)

NASA Astrophysics Data System (ADS)

Russ, M.; Shankar, A.; Jain, A.; Setlur Nagesh, S. V.; Ionita, C. N.; Scott, C.; Karim, K. S.; Bednarek, D. R.; Rudin, S.

2016-03-01

A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25μm pixel pitch, and 1000μm thick a-Se layer operating at 10V/μm bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-pre-whitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal- spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide break- through abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices.

Quantitative comparison using Generalized Relative Object Detectability (G-ROD) metrics of an amorphous selenium detector with high resolution Microangiographic Fluoroscopes (MAF) and standard flat panel detectors (FPD)

PubMed Central

Russ, M.; Shankar, A.; Jain, A.; Setlur Nagesh, S. V.; Ionita, C. N.; Scott, C.; Karim, K. S.; Bednarek, D. R.; Rudin, S.

2017-01-01

A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25μm pixel pitch, and 1000μm thick a-Se layer operating at 10V/μm bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-prewhitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal-spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide breakthrough abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices. PMID:28615795

DOE Office of Scientific and Technical Information (OSTI.GOV)

Philipp, Hugh T.; Tate, Mark W.; Purohit, Prafull

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 atmore » 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. Lastly, we detail the characteristics, operation, testing and application of the detector.« less

The wide field imager instrument for Athena

NASA Astrophysics Data System (ADS)

Meidinger, Norbert; Eder, Josef; Eraerds, Tanja; Nandra, Kirpal; Pietschner, Daniel; Plattner, Markus; Rau, Arne; Strecker, Rafael

2016-07-01

The WFI (Wide Field Imager) instrument is planned to be one of two complementary focal plane cameras on ESA's next X-ray observatory Athena. It combines unprecedented survey power through its large field of view of 40 amin x 40 amin together with excellent count rate capability (>= 1 Crab). The energy resolution of the silicon sensor is state-of-the-art in the energy band of interest from 0.2 keV to 15 keV, e.g. the full width at half maximum of a line at 7 keV will be <= 170 eV until the end of the nominal mission phase. This performance is accomplished by using DEPFET active pixel sensors with a pixel size of 130 μm x 130 μm well suited to the on-axis angular resolution of 5 arcsec half energy width (HEW) of the mirror system. Each DEPFET pixel is a combined sensor-amplifier structure with a MOSFET integrated onto a fully depleted 450 μm thick silicon bulk. Two detectors are planned for the WFI instrument: A large-area detector comprising four sensors with a total of 1024 x 1024 pixels and a fast detector optimized for high count rate observations. This high count rate capable detector permits for bright point sources with an intensity of 1 Crab a throughput of more than 80% and a pile-up of less than 1%. The fast readout of the DEPFET pixel matrices is facilitated by an ASIC development, called VERITAS-2. Together with the Switcher-A, a control ASIC that allows for operation of the DEPFET in rolling shutter mode, these elements form the key components of the WFI detectors. The detectors are surrounded by a graded-Z shield, which has in particular the purpose to avoid fluorescence lines that would contribute to the instrument background. Together with ultra-thin coating of the sensor and particle identification by the detector itself, the particle induced background shall be minimized in order to achieve the scientific requirement of a total instrumental background value smaller than 5 x 10-3 cts/cm2/s/keV. Each detector has its dedicated detector electronics (DE) for supply and data acquisition. Due to the high frame rate in combination with the large pixel array, signal correction and event filtering have to be done on-board and in real-time as the raw data rate would by far exceed the feasible telemetry rate. The data streams are merged and compressed in the Instrument Control and Power distribution Unit (ICPU). The ICPU is the data, control and power interface of the WFI to the Athena spacecraft. The WFI instrument comprises in addition a filter wheel (FW) in front of the camera as well as an optical stray-light baffle. In the current phase A of the Athena project, the technology development is performed. At its end, breadboard models will be developed and tested to demonstrate a technical readiness level (TRL) of at least 5 for the various WFI subsystems before mission adoption in 2020.

SU-D-204-05: Quantitative Comparison of a High Resolution Micro-Angiographic Fluoroscopic (MAF) Detector with a Standard Flat Panel Detector (FPD) Using the New Metric of Generalized Measured Relative Object Detectability (GM-ROD)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russ, M; Ionita, C; Bednarek, D

Purpose: In endovascular image-guided neuro-interventions, visualization of fine detail is paramount. For example, the ability of the interventionist to visualize the stent struts depends heavily on the x-ray imaging detector performance. Methods: A study to examine the relative performance of the high resolution MAF-CMOS (pixel size 75µm, Nyquist frequency 6.6 cycles/mm) and a standard Flat Panel Detector (pixel size 194µm, Nyquist frequency 2.5 cycles/mm) detectors in imaging a neuro stent was done using the Generalized Measured Relative Object Detectability (GM-ROD) metric. Low quantum noise images of a deployed stent were obtained by averaging 95 frames obtained by both detectors withoutmore » changing other exposure or geometric parameters. The square of the Fourier transform of each image is taken and divided by the generalized normalized noise power spectrum to give an effective measured task-specific signal-to-noise ratio. This expression is then integrated from 0 to each of the detector’s Nyquist frequencies, and the GM-ROD value is determined by taking a ratio of the integrals for the MAF-CMOS to that of the FPD. The lower bound of integration can be varied to emphasize high frequencies in the detector comparisons. Results: The MAF-CMOS detector exhibits vastly superior performance over the FPD when integrating over all frequencies, yielding a GM-ROD value of 63.1. The lower bound of integration was stepped up in increments of 0.5 cycles/mm for higher frequency comparisons. As the lower bound increased, the GM-ROD value was augmented, reflecting the superior performance of the MAF-CMOS in the high frequency regime. Conclusion: GM-ROD is a versatile metric that can provide quantitative detector and task dependent comparisons that can be used as a basis for detector selection. Supported by NIH Grant: 2R01EB002873 and an equipment grant from Toshiba Medical Systems Corporation.« less

Advancements in DEPMOSFET device developments for XEUS

NASA Astrophysics Data System (ADS)

Treis, J.; Bombelli, L.; Eckart, R.; Fiorini, C.; Fischer, P.; Hälker, O.; Herrmann, S.; Lechner, P.; Lutz, G.; Peric, I.; Porro, M.; Richter, R. H.; Schaller, G.; Schopper, F.; Soltau, H.; Strüder, L.; Wölfel, S.

2006-06-01

DEPMOSFET based Active Pixel Sensor (APS) matrices are a new detector concept for X-ray imaging spectroscopy missions. They can cope with the challenging requirements of the XEUS Wide Field Imager and combine excellent energy resolution, high speed readout and low power consumption with the attractive feature of random accessibility of pixels. From the evaluation of first prototypes, new concepts have been developed to overcome the minor drawbacks and problems encountered for the older devices. The new devices will have a pixel size of 75 μm × 75 μm. Besides 64 × 64 pixel arrays, prototypes with a sizes of 256 × 256 pixels and 128 × 512 pixels and an active area of about 3.6 cm2 will be produced, a milestone on the way towards the fully grown XEUS WFI device. The production of these improved devices is currently on the way. At the same time, the development of the next generation of front-end electronics has been started, which will permit to operate the sensor devices with the readout speed required by XEUS. Here, a summary of the DEPFET capabilities, the concept of the sensors of the next generation and the new front-end electronics will be given. Additionally, prospects of new device developments using the DEPFET as a sensitive element are shown, e.g. so-called RNDR-pixels, which feature repetitive non-destructive readout to lower the readout noise below the 1 e - ENC limit.

A Medipix3 readout system based on the National Instruments FlexRIO card and using the LabVIEW programming environment

NASA Astrophysics Data System (ADS)

Horswell, I.; Gimenez, E. N.; Marchal, J.; Tartoni, N.

2011-01-01

Hybrid silicon photon-counting detectors are becoming standard equipment for many synchrotron applications. The latest in the Medipix family of read-out chips designed as part of the Medipix Collaboration at CERN is the Medipix3, which while maintaining the same pixel size as its predecessor, offers increased functionality and operating modes. The active area of the Medipix3 chip is approx 14mm × 14mm (containing 256 × 256 pixels) which is not large enough for many detector applications, this results in the need to tile many sensors and chips. As a first step on the road to develop such a detector, it was decided to build a prototype single chip readout system to gain the necessary experience in operating a Medipix3 chip. To provide a flexible learning and development tool it was decided to build an interface based on the recently released FlexRIOTM system from National Instruments and to use the LabVIEWTM graphical programming environment. This system and the achieved performance are described in this paper.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagesh, S Setlur; Rana, R; Russ, M

Purpose: CMOS-based aSe detectors compared to CsI-TFT-based flat panels have the advantages of higher spatial sampling due to smaller pixel size and decreased blurring characteristic of direct rather than indirect detection. For systems with such detectors, the limiting factor degrading image resolution then becomes the focal-spot geometric unsharpness. This effect can seriously limit the use of such detectors in areas such as cone beam computed tomography, clinical fluoroscopy and angiography. In this work a technique to remove the effect of focal-spot blur is presented for a simulated aSe detector. Method: To simulate images from an aSe detector affected with focal-spotmore » blur, first a set of high-resolution images of a stent (FRED from Microvention, Inc.) were acquired using a 75µm pixel size Dexela-Perkin-Elmer detector and averaged to reduce quantum noise. Then the averaged image was blurred with a known Gaussian blur at two different magnifications to simulate an idealized focal spot. The blurred images were then deconvolved with a set of different Gaussian blurs to remove the effect of focal-spot blurring using a threshold-based, inverse-filtering method. Results: The blur was removed by deconvolving the images using a set of Gaussian functions for both magnifications. Selecting the correct function resulted in an image close to the original; however, selection of too wide a function would cause severe artifacts. Conclusion: Experimentally, focal-spot blur at different magnifications can be measured using a pin hole with a high resolution detector. This spread function can be used to deblur the input images that are acquired at corresponding magnifications to correct for the focal spot blur. For CBCT applications, the magnification of specific objects can be obtained using initial reconstructions then corrected for focal-spot blurring to improve resolution. Similarly, if object magnification can be determined such correction may be applied in fluoroscopy and angiography.« less

Charge Sharing and Charge Loss in a Cadmium-Zinc-Telluride Fine-Pixel Detector Array

NASA Technical Reports Server (NTRS)

Gaskin, J. A.; Sharma, D. P.; Ramsey, B. D.; Six, N. Frank (Technical Monitor)

2002-01-01

Because of its high atomic number, room temperature operation, low noise, and high spatial resolution a Cadmium-Zinc-Telluride (CZT) multi-pixel detector is ideal for hard x-ray astrophysical observation. As part of on-going research at MSFC (Marshall Space Flight Center) to develop multi-pixel CdZnTe detectors for this purpose, we have measured charge sharing and charge loss for a 4x4 (750micron pitch), lmm thick pixel array and modeled these results using a Monte-Carlo simulation. This model was then used to predict the amount of charge sharing for a much finer pixel array (with a 300micron pitch). Future work will enable us to compare the simulated results for the finer array to measured values.

Optimization of a large-area detector-block based on SiPM and pixelated LYSO crystal arrays.

PubMed

Calva-Coraza, E; Alva-Sánchez, H; Murrieta-Rodríguez, T; Martínez-Dávalos, A; Rodríguez-Villafuerte, M

2017-10-01

We present the performance evaluation of a large-area detector module based on the ArrayC-60035-64P, an 8×8 array of tileable, 7.2mm pitch, silicon photomultipliers (SiPM) by SensL, covering a total area of 57.4mm×57.4mm. We characterized the ArrayC-60035-64P, operating at room temperature, using LYSO pixelated crystal arrays of different pitch sizes (1.075, 1.430, 1.683, 2.080 and 2.280mm) to determine the resolvable crystal size. After an optimization process, a 7mm thick coupling light guide was used for all crystal pitches. To identify the interaction position a 16-channel (8 columns, 8 rows) symmetric charge division (SCD) readout board together with a center-of-gravity algorithm was used. Based on this, we assembled the detector modules using a 40×40 LYSO, 1.43mm pitch array, covering the total detector area. Calibration was performed using a 137 Cs source resulting in excellent crystal maps with minor geometric distortion, a mean 4.1 peak-to-valley ratio and 9.6% mean energy resolution for 662keV photons in the central region. The resolvability index was calculated in the x and y directions with values under 0.42 in all cases. We show that these large area SiPM arrays, combined with a 16-channel SCD readout board, can offer high spatial resolution, without processing a big number of signals, attaining excellent energy resolution and detector uniformity. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Recent progress and development of a speedster-EXD: a new event-triggered hybrid CMOS x-ray detector

NASA Astrophysics Data System (ADS)

Griffith, Christopher V.; Falcone, Abraham D.; Prieskorn, Zachary R.; Burrows, David N.

2015-08-01

We present the characterization of a new event-driven X-ray hybrid CMOS detector developed by Penn State University in collaboration with Teledyne Imaging Sensors. Along with its low susceptibility to radiation damage, low power consumption, and fast readout time to avoid pile-up, the Speedster-EXD has been designed with the capability to limit its readout to only those pixels containing charge, thus enabling even faster effective frame rates. The threshold for the comparator in each pixel can be set by the user so that only pixels with signal above the set threshold are read out. The Speedster-EXD hybrid CMOS detector also has two new in-pixel features that reduce noise from known noise sources: (1) a low-noise, high-gain CTIA amplifier to eliminate crosstalk from interpixel capacitance (IPC) and (2) in-pixel CDS subtraction to reduce kTC noise. We present the read noise, dark current, IPC, energy resolution, and gain variation measurements of one Speedster-EXD detector.

Investigating the Inverse Square Law with the Timepix Hybrid Silicon Pixel Detector: A CERN [at] School Demonstration Experiment

ERIC Educational Resources Information Center

Whyntie, T.; Parker, B.

2013-01-01

The Timepix hybrid silicon pixel detector has been used to investigate the inverse square law of radiation from a point source as a demonstration of the CERN [at] school detector kit capabilities. The experiment described uses a Timepix detector to detect the gamma rays emitted by an [superscript 241]Am radioactive source at a number of different…

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

NASA Technical Reports Server (NTRS)

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Togno, M., E-mail: michele.togno@iba-group.com; Department of Radiation Oncology, Technische Universität München, Klinikum rechts der Isar, Munich 81675; IBA Dosimetry GmbH, Schwarzenbruck 90592

Purpose: To characterize a new air vented ionization chamber technology, suitable to build detector arrays with small pixel pitch and independence of sensitivity on dose per pulse. Methods: The prototype under test is a linear array of air vented ionization chambers, consisting of 80 pixels with 3.5 mm pixel pitch distance and a sensitive volume of about 4 mm{sup 3}. The detector has been characterized with {sup 60}Co radiation and MV x rays from different linear accelerators (with flattened and unflattened beam qualities). Sensitivity dependence on dose per pulse has been evaluated under MV x rays by changing both themore » source to detector distance and the beam quality. Bias voltage has been varied in order to evaluate the charge collection efficiency in the most critical conditions. Relative dose profiles have been measured for both flattened and unflattened distributions with different field sizes. The reference detectors were a commercial array of ionization chambers and an amorphous silicon flat panel in direct conversion configuration. Profiles of dose distribution have been measured also with intensity modulated radiation therapy (IMRT), stereotactic radiosurgery (SRS), and volumetric modulated arc therapy (VMAT) patient plans. Comparison has been done with a commercial diode array and with Gafchromic EBT3 films. Results: Repeatability and stability under continuous gamma irradiation are within 0.3%, in spite of low active volume and sensitivity (∼200 pC/Gy). Deviation from linearity is in the range [0.3%, −0.9%] for a dose of at least 20 cGy, while a worsening of linearity is observed below 10 cGy. Charge collection efficiency with 2.67 mGy/pulse is higher than 99%, leading to a ±0.9% sensitivity change in the range 0.09–2.67 mGy/pulse (covering all flattened and unflattened beam qualities). Tissue to phantom ratios show an agreement within 0.6% with the reference detector up to 34 cm depth. For field sizes in the range 2 × 2 to 15 × 15 cm{sup 2}, the output factors are in agreement with a thimble chamber within 2%, while with 25 × 25 cm{sup 2} field size, an underestimation of 4.0% was found. Agreement of field and penumbra width measurements with the flat panel is of the order of 1 mm down to 1 × 1 cm{sup 2} field size. Flatness and symmetry values measured with the 1D array and the reference detectors are comparable, and differences are always smaller than 1%. Angular dependence of the detector, when compared to measurements taken with a cylindrical chamber in the same phantom, is as large as 16%. This includes inhomogeneity and asymmetry of the design, which during plan verification are accounted for by the treatment planning system (TPS). The detector is capable to reproduce the dose distributions of IMRT and VMAT plans with a maximum deviation from TPS of 3.0% in the target region. In the case of VMAT and SRS plans, an average (maximum) deviation of the order of 1% (4%) from films has been measured. Conclusions: The investigated technology appears to be useful both for Linac QA and patient plan verification, especially in treatments with steep dose gradients and nonuniform dose rates such as VMAT and SRS. Major limitations of the present prototype are the linearity at low dose, which can be solved by optimizing the readout electronics, and the underestimation of output factors with large field sizes. The latter problem is presently not completely understood and will require further investigations.« less

Evaluation of a CdTe semiconductor based compact gamma camera for sentinel lymph node imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russo, Paolo; Curion, Assunta S.; Mettivier, Giovanni

2011-03-15

Purpose: The authors assembled a prototype compact gamma-ray imaging probe (MediPROBE) for sentinel lymph node (SLN) localization. This probe is based on a semiconductor pixel detector. Its basic performance was assessed in the laboratory and clinically in comparison with a conventional gamma camera. Methods: The room-temperature CdTe pixel detector (1 mm thick) has 256x256 square pixels arranged with a 55 {mu}m pitch (sensitive area 14.08x14.08 mm{sup 2}), coupled pixel-by-pixel via bump-bonding to the Medipix2 photon-counting readout CMOS integrated circuit. The imaging probe is equipped with a set of three interchangeable knife-edge pinhole collimators (0.94, 1.2, or 2.1 mm effective diametermore » at 140 keV) and its focal distance can be regulated in order to set a given field of view (FOV). A typical FOV of 70 mm at 50 mm skin-to-collimator distance corresponds to a minification factor 1:5. The detector is operated at a single low-energy threshold of about 20 keV. Results: For {sup 99m}Tc, at 50 mm distance, a background-subtracted sensitivity of 6.5x10{sup -3} cps/kBq and a system spatial resolution of 5.5 mm FWHM were obtained for the 0.94 mm pinhole; corresponding values for the 2.1 mm pinhole were 3.3x10{sup -2} cps/kBq and 12.6 mm. The dark count rate was 0.71 cps. Clinical images in three patients with melanoma indicate detection of the SLNs with acquisition times between 60 and 410 s with an injected activity of 26 MBq {sup 99m}Tc and prior localization with standard gamma camera lymphoscintigraphy. Conclusions: The laboratory performance of this imaging probe is limited by the pinhole collimator performance and the necessity of working in minification due to the limited detector size. However, in clinical operative conditions, the CdTe imaging probe was effective in detecting SLNs with adequate resolution and an acceptable sensitivity. Sensitivity is expected to improve with the future availability of a larger CdTe detector permitting operation at shorter distances from the patient skin.« less

Development of a cylindrical tracking detector with multichannel scintillation fibers and pixelated photon detector readout

NASA Astrophysics Data System (ADS)

Akazawa, Y.; Miwa, K.; Honda, R.; Shiozaki, T.; Chiga, N.

2015-07-01

We are developing a cylindrical tracking detector for a Σp scattering experiment in J-PARC with scintillation fibers and the Pixelated Photon Detector (PPD) readout, which is called as cylindrical fiber tracker (CFT), in order to reconstruct trajectories of charged particles emitted inside CFT. CFT works not only as a tracking detector but also a particle identification detector from energy deposits. A prototype CFT consisting of two straight layers and one spiral layer was constructed. About 1100 scintillation fibers with a diameter of 0.75 mm (Kuraray SCSF-78 M) were used. Each fiber signal was read by Multi-Pixel Photon Counter (MPPC, HPK S10362-11-050P, 1×1 mm2, 400 pixels) fiber by fiber. MPPCs were handled with Extended Analogue Silicon Photomultipliers Integrated ReadOut Chip (EASIROC) boards, which were developed for the readout of a large number of MPPCs. The energy resolution of one layer was 28% for a 70 MeV proton where the energy deposit in fibers was 0.7 MeV.

Study of a GaAs:Cr-based Timepix detector using synchrotron facility

NASA Astrophysics Data System (ADS)

Smolyanskiy, P.; Kozhevnikov, D.; Bakina, O.; Chelkov, G.; Dedovich, D.; Kuper, K.; Leyva Fabelo, A.; Zhemchugov, A.

2017-11-01

High resistivity gallium arsenide compensated by chromium fabricated by Tomsk State University has demonstrated a good suitability as a sensor material for hybrid pixel detectors used in X-ray imaging systems with photon energies up to 60 keV. The material is available with a thickness up to 1 mm and due to its Z number a high absorption efficiency in this energy region is provided. However, the performance of thick GaAs:Cr-based detectors in spectroscopic applications is limited by readout electronics with relatively small pixels due to the charge sharing effect. In this paper, we present the experimental investigation of the charge sharing effect contribution in the GaAs:Cr-based Timepix detector. By means of scanning the detector with a pencil photon beam generated by the synchrotron facility, the geometrical mapping of pixel sensitivity is obtained, as well as the energy resolution of a single pixel. The experimental results are supported by numerical simulations. The observed limitation of the GaAs:Cr-based Timepix detector for the high flux X-ray imaging is discussed.

Opto-mechanical design of PANIC

NASA Astrophysics Data System (ADS)

Fried, Josef W.; Baumeister, Harald; Huber, Armin; Laun, Werner; Rohloff, Ralf-Rainer; Concepción Cárdenas, M.

2010-07-01

PANIC, the Panoramic Near-Infrared Camera, is a new instrument for the Calar Alto Observatory. A 4x4 k detector yields a field of view of 0.5x0.5 degrees at a pixel scale of 0.45 arc sec/pixel at the 2.2m telescope. PANIC can be used also at the 3.5m telescope with half the pixel scale. The optics consists of 9 lenses and 3 folding mirrors. Mechanical tolerances are as small as 50 microns for some elements. PANIC will have a low thermal background due to cold stops. Read-out is done with MPIA's own new electronics which allows read-out of 132 channels in parallel. Weight and size limits lead to interesting design features. Here we describe the opto-mechanical design.

WE-G-204-06: Grid-Line Artifact Minimization for High Resolution Detectors Using Iterative Residual Scatter Correction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rana, R; Bednarek, D; Rudin, S

2015-06-15

Purpose: Anti-scatter grid-line artifacts are more prominent for high-resolution x-ray detectors since the fraction of a pixel blocked by the grid septa is large. Direct logarithmic subtraction of the artifact pattern is limited by residual scattered radiation and we investigate an iterative method for scatter correction. Methods: A stationary Smit-Rοntgen anti-scatter grid was used with a high resolution Dexela 1207 CMOS X-ray detector (75 µm pixel size) to image an artery block (Nuclear Associates, Model 76-705) placed within a uniform head equivalent phantom as the scattering source. The image of the phantom was divided by a flat-field image obtained withoutmore » scatter but with the grid to eliminate grid-line artifacts. Constant scatter values were subtracted from the phantom image before dividing by the averaged flat-field-with-grid image. The standard deviation of pixel values for a fixed region of the resultant images with different subtracted scatter values provided a measure of the remaining grid-line artifacts. Results: A plot of the standard deviation of image pixel values versus the subtracted scatter value shows that the image structure noise reaches a minimum before going up again as the scatter value is increased. This minimum corresponds to a minimization of the grid-line artifacts as demonstrated in line profile plots obtained through each of the images perpendicular to the grid lines. Artifact-free images of the artery block were obtained with the optimal scatter value obtained by this iterative approach. Conclusion: Residual scatter subtraction can provide improved grid-line artifact elimination when using the flat-field with grid “subtraction” technique. The standard deviation of image pixel values can be used to determine the optimal scatter value to subtract to obtain a minimization of grid line artifacts with high resolution x-ray imaging detectors. This study was supported by NIH Grant R01EB002873 and an equipment grant from Toshiba Medical Systems Corp.« less

Focal Plane Detectors for the Advanced Gamma-Ray Imaging System (AGIS)

NASA Astrophysics Data System (ADS)

Wagner, Robert G.; AGIS Photodetector Group; Byrum, K.; Drake, G.; Falcone, A.; Funk, S.; Horan, D.; Mukherjee, R.; Tajima, H.; Williams, D.

2008-03-01

The Advanced Gamma-Ray Imaging System (AGIS) is a concept for the next generation observatory in ground-based very high energy gamma-ray astronomy. It is being designed to achieve a significant improvement in sensitivity compared to current Imaging Air Cherenkov Telescope (IACT) Arrays. One of the main requirements in order that AGIS fulfill this goal will be to achieve higher angular resolution than current IACTs. Simulations show that a substantial improvement in angular resolution may be achieved if the pixel size is reduced to less than 0.05 deg, i.e. two to three times smaller than the pixel size of current IACT cameras. With finer pixelation and the plan to deploy on the order of 100 telescopes in the AGIS array, the channel count will exceed 1,000,000 imaging pixels. High uniformity and long mean time-to-failure will be important aspects of a successful photodetector technology choice. Here we present alternatives being considered for AGIS, including both silicon photomultipliers (SiPMs) and multi-anode photomultipliers (MAPMTs). Results from laboratory testing of MAPMTs and SiPMs are presented along with results from the first incorporation of these devices in cameras on test bed Cherenkov telescopes.

The SLD VXD3 detector and its initial performance

NASA Astrophysics Data System (ADS)

Abe, K.; Arodzero, A.; Baltay, C.; Brau, J.; Breidenbach, M.; Burrows, P. N.; Chou, A.; Crawford, G.; Damerell, C.; Dervan, P.; Dong, D.; Emmet, W.; English, R.; Etzion, E.; Foss, M.; Frey, R.; Haller, G.; Hasuko, K.; Hertzbach, S.; Hoeflich, J.; Huber, J.; Huffer, M.; Jackson, D.; Jaros, J.; Kelsy, J.; Kendall, H.; Lee, I.; Lia, V.; Lintern, L.; Liu, M.; Manly, S.; Masuda, H.; Moore, T.; Nagamine, T.; Ohishi, N.; Osborne, L.; Ross, D.; Russell, J.; Serbo, V.; Sinev, N.; Sinnott, J.; Skarpaas, K. Viii; Smy, M.; Snyder, J.; Strauss, M.; Dong, S.; Suekane, F.; Taylor, F.; Trandafir, A.; Usher, T.; Verdier, R.; Watts, S.; Weiss, E.; Yashima, J.; Yuta, H.; Zapalac, G.

1997-02-01

The SLD collaboration completed construction of a new CCD vertex detector (VXD3) in January 1996 and started data taking in April 1996 with the new system. VXD3 is an upgrade of the original CCD vertex detector, VXD2, which had successfully operated in SLD for three years. VXD3 consists of 96 large area CCDs, each having 3.2 million 20 μm × 20 μm pixels. By reducing the detector material and lengthening the lever arm, VXD3 is expected to improve secondary vertex resolution by about a factor of two compared with VXD2. The new three-layered structure enables stand-alone tracking without any ambiguity and its extended size along the beam direction improves the polar-angle coverage to |cos θ| < 0.85. An overview of this detector system and its initial performance are described.

The stability of TlBr detectors at low temperature

NASA Astrophysics Data System (ADS)

Dönmez, Burçin; He, Zhong; Kim, Hadong; Cirignano, Leonard J.; Shah, Kanai S.

2010-11-01

Thallium bromide (TlBr) is a promising semiconductor detector material due to its high atomic number (Tl: 81, Br: 35), high density (7.56 g/cm 3) and wide band gap (2.68 eV). Current TlBr detectors suffer from polarization, which causes performance degradation over time when high voltage is applied. A 4.6-mm thick TlBr detector with pixellated anodes made by Radiation Monitoring Devices Inc. was used in the experiments. The detector has a planar cathode and nine anode pixels surrounded by a guard ring. The pixel pitch is 1.0-mm. Digital pulse waveforms of preamplifier outputs were recorded using a multi-channel GaGe PCI digitizer board for pulse shaping. Several experiments were carried out at -20 °C while the detector was under bias for over a month. No polarization effect was observed and the detector's spectroscopic performance improved over time. Energy resolution of 1.5% FWHM at 662 keV has been measured without depth correction at -2000 V cathode bias. Average electron mobility-lifetime of (5.7±0.8) ×10 -3 cm 2/V has been measured from four anode pixels.

A detector interferometric calibration experiment for high precision astrometry

NASA Astrophysics Data System (ADS)

Crouzier, A.; Malbet, F.; Henault, F.; Léger, A.; Cara, C.; LeDuigou, J. M.; Preis, O.; Kern, P.; Delboulbe, A.; Martin, G.; Feautrier, P.; Stadler, E.; Lafrasse, S.; Rochat, S.; Ketchazo, C.; Donati, M.; Doumayrou, E.; Lagage, P. O.; Shao, M.; Goullioud, R.; Nemati, B.; Zhai, C.; Behar, E.; Potin, S.; Saint-Pe, M.; Dupont, J.

2016-11-01

Context. Exoplanet science has made staggering progress in the last two decades, due to the relentless exploration of new detection methods and refinement of existing ones. Yet astrometry offers a unique and untapped potential of discovery of habitable-zone low-mass planets around all the solar-like stars of the solar neighborhood. To fulfill this goal, astrometry must be paired with high precision calibration of the detector. Aims: We present a way to calibrate a detector for high accuracy astrometry. An experimental testbed combining an astrometric simulator and an interferometric calibration system is used to validate both the hardware needed for the calibration and the signal processing methods. The objective is an accuracy of 5 × 10-6 pixel on the location of a Nyquist sampled polychromatic point spread function. Methods: The interferometric calibration system produced modulated Young fringes on the detector. The Young fringes were parametrized as products of time and space dependent functions, based on various pixel parameters. The minimization of function parameters was done iteratively, until convergence was obtained, revealing the pixel information needed for the calibration of astrometric measurements. Results: The calibration system yielded the pixel positions to an accuracy estimated at 4 × 10-4 pixel. After including the pixel position information, an astrometric accuracy of 6 × 10-5 pixel was obtained, for a PSF motion over more than five pixels. In the static mode (small jitter motion of less than 1 × 10-3 pixel), a photon noise limited precision of 3 × 10-5 pixel was reached.

Test apparatus to monitor time-domain signals from semiconductor-detector pixel arrays

NASA Astrophysics Data System (ADS)

Haston, Kyle; Barber, H. Bradford; Furenlid, Lars R.; Salçin, Esen; Bora, Vaibhav

2011-10-01

Pixellated semiconductor detectors, such as CdZnTe, CdTe, or TlBr, are used for gamma-ray imaging in medicine and astronomy. Data analysis for these detectors typically estimates the position (x, y, z) and energy (E) of each interacting gamma ray from a set of detector signals {Si} corresponding to completed charge transport on the hit pixel and any of its neighbors that take part in charge sharing, plus the cathode. However, it is clear from an analysis of signal induction, that there are transient signal on all pixel electrodes during the charge transport and, when there is charge trapping, small negative residual signals on all electrodes. If we wish to optimally obtain the event parameters, we should take all these signals into account. We wish to estimate x,y,z and E from the set of all electrode signals, {Si(t)}, including time dependence, using maximum-likelihood techniques[1]. To do this, we need to determine the probability of the electrode signals, given the event parameters {x, y, z, E}, i.e. Pr( {Si(t)} | {x, y, z, E} ). Thus we need to map the detector response of all pixels, {Si(t)}, for a large number of events with known x,y,z and E.In this paper we demonstrate the existence of the transient signals and residual signals and determine their magnitudes. They are typically 50-100 times smaller than the hit-pixel signals. We then describe development of an apparatus to measure the response of a 16-pixel semiconductor detector and show some preliminary results. We also discuss techniques for measuring the event parameters for individual gamma-ray interactions, a requirement for determining Pr( {Si(t)} | {x, y, z, E}).

Determination of the conversion gain and the accuracy of its measurement for detector elements and arrays

NASA Astrophysics Data System (ADS)

Beecken, B. P.; Fossum, E. R.

1996-07-01

Standard statistical theory is used to calculate how the accuracy of a conversion-gain measurement depends on the number of samples. During the development of a theoretical basis for this calculation, a model is developed that predicts how the noise levels from different elements of an ideal detector array are distributed. The model can also be used to determine what dependence the accuracy of measured noise has on the size of the sample. These features have been confirmed by experiment, thus enhancing the credibility of the method for calculating the uncertainty of a measured conversion gain. detector-array uniformity, charge coupled device, active pixel sensor.

Tracking Detectors in the STAR Experiment at RHIC

NASA Astrophysics Data System (ADS)

Wieman, Howard

2015-04-01

The STAR experiment at RHIC is designed to measure and identify the thousands of particles produced in 200 Gev/nucleon Au on Au collisions. This talk will focus on the design and construction of two of the main tracking detectors in the experiment, the TPC and the Heavy Flavor Tracker (HFT) pixel detector. The TPC is a solenoidal gas filled detector 4 meters in diameter and 4.2 meters long. It provides precise, continuous tracking and rate of energy loss in the gas (dE/dx) for particles at + - 1 units of pseudo rapidity. The tracking in a half Tesla magnetic field measures momentum and dE/dX provides particle ID. To detect short lived particles tracking close to the point of interaction is required. The HFT pixel detector is a two-layered, high resolution vertex detector located at a few centimeters radius from the collision point. It determines origins of the tracks to a few tens of microns for the purpose of extracting displaced vertices, allowing the identification of D mesons and other short-lived particles. The HFT pixel detector uses detector chips developed by the IPHC group at Strasbourg that are based on standard IC Complementary Metal-Oxide-Semiconductor (CMOS) technology. This is the first time that CMOS pixel chips have been incorporated in a collider application.

Microradiography with Semiconductor Pixel Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jakubek, Jan; Cejnarova, Andrea; Dammer, Jiri

High resolution radiography (with X-rays, neutrons, heavy charged particles, ...) often exploited also in tomographic mode to provide 3D images stands as a powerful imaging technique for instant and nondestructive visualization of fine internal structure of objects. Novel types of semiconductor single particle counting pixel detectors offer many advantages for radiation imaging: high detection efficiency, energy discrimination or direct energy measurement, noiseless digital integration (counting), high frame rate and virtually unlimited dynamic range. This article shows the application and potential of pixel detectors (such as Medipix2 or TimePix) in different fields of radiation imaging.

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

DOEpatents

Perez-Mendez, Victor; Goodman, Claude A.

1996-01-01

Apparatus 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.

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

DOEpatents

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, Steve; Haji-Sheikh, Michael; Huntington, Andrew

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 gatingmore » 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.« less

A comparison of the performance of modern screen-film and digital mammography systems.

PubMed

Monnin, P; Gutierrez, D; Bulling, S; Lepori, D; Valley, J-F; Verdun, F R

2005-06-07

This work compares the detector performance and image quality of the new Kodak Min-R EV mammography screen-film system with the Fuji CR Profect detector and with other current mammography screen-film systems from Agfa, Fuji and Kodak. Basic image quality parameters (MTF, NPS, NEQ and DQE) were evaluated for a 28 kV Mo/Mo (HVL = 0.646 mm Al) beam using different mAs exposure settings. Compared with other screen-film systems, the new Kodak Min-R EV detector has the highest contrast and a low intrinsic noise level, giving better NEQ and DQE results, especially at high optical density. Thus, the properties of the new mammography film approach those of a fine mammography detector, especially at low frequency range. Screen-film systems provide the best resolution. The presampling MTF of the digital detector has a value of 15% at the Nyquist frequency and, due to the spread size of the laser beam, the use of a smaller pixel size would not permit a significant improvement of the detector resolution. The dual collection reading technology increases significantly the low frequency DQE of the Fuji CR system that can at present compete with the most efficient mammography screen-film systems.

High throughput reconfigurable data analysis system

NASA Technical Reports Server (NTRS)

Bearman, Greg (Inventor); Pelletier, Michael J. (Inventor); Seshadri, Suresh (Inventor); Pain, Bedabrata (Inventor)

2008-01-01

The present invention relates to a system and method for performing rapid and programmable analysis of data. The present invention relates to a reconfigurable detector comprising at least one array of a plurality of pixels, where each of the plurality of pixels can be selected to receive and read-out an input. The pixel array is divided into at least one pixel group for conducting a common predefined analysis. Each of the pixels has a programmable circuitry programmed with a dynamically configurable user-defined function to modify the input. The present detector also comprises a summing circuit designed to sum the modified input.

Enhancing spatial resolution of (18)F positron imaging with the Timepix detector by classification of primary fired pixels using support vector machine.

PubMed

Wang, Qian; Liu, Zhen; Ziegler, Sibylle I; Shi, Kuangyu

2015-07-07

Position-sensitive positron cameras using silicon pixel detectors have been applied for some preclinical and intraoperative clinical applications. However, the spatial resolution of a positron camera is limited by positron multiple scattering in the detector. An incident positron may fire a number of successive pixels on the imaging plane. It is still impossible to capture the primary fired pixel along a particle trajectory by hardware or to perceive the pixel firing sequence by direct observation. Here, we propose a novel data-driven method to improve the spatial resolution by classifying the primary pixels within the detector using support vector machine. A classification model is constructed by learning the features of positron trajectories based on Monte-Carlo simulations using Geant4. Topological and energy features of pixels fired by (18)F positrons were considered for the training and classification. After applying the classification model on measurements, the primary fired pixels of the positron tracks in the silicon detector were estimated. The method was tested and assessed for [(18)F]FDG imaging of an absorbing edge protocol and a leaf sample. The proposed method improved the spatial resolution from 154.6   ±   4.2 µm (energy weighted centroid approximation) to 132.3   ±   3.5 µm in the absorbing edge measurements. For the positron imaging of a leaf sample, the proposed method achieved lower root mean square error relative to phosphor plate imaging, and higher similarity with the reference optical image. The improvements of the preliminary results support further investigation of the proposed algorithm for the enhancement of positron imaging in clinical and preclinical applications.

Enhancing spatial resolution of 18F positron imaging with the Timepix detector by classification of primary fired pixels using support vector machine

NASA Astrophysics Data System (ADS)

Wang, Qian; Liu, Zhen; Ziegler, Sibylle I.; Shi, Kuangyu

2015-07-01

Position-sensitive positron cameras using silicon pixel detectors have been applied for some preclinical and intraoperative clinical applications. However, the spatial resolution of a positron camera is limited by positron multiple scattering in the detector. An incident positron may fire a number of successive pixels on the imaging plane. It is still impossible to capture the primary fired pixel along a particle trajectory by hardware or to perceive the pixel firing sequence by direct observation. Here, we propose a novel data-driven method to improve the spatial resolution by classifying the primary pixels within the detector using support vector machine. A classification model is constructed by learning the features of positron trajectories based on Monte-Carlo simulations using Geant4. Topological and energy features of pixels fired by 18F positrons were considered for the training and classification. After applying the classification model on measurements, the primary fired pixels of the positron tracks in the silicon detector were estimated. The method was tested and assessed for [18F]FDG imaging of an absorbing edge protocol and a leaf sample. The proposed method improved the spatial resolution from 154.6   ±   4.2 µm (energy weighted centroid approximation) to 132.3   ±   3.5 µm in the absorbing edge measurements. For the positron imaging of a leaf sample, the proposed method achieved lower root mean square error relative to phosphor plate imaging, and higher similarity with the reference optical image. The improvements of the preliminary results support further investigation of the proposed algorithm for the enhancement of positron imaging in clinical and preclinical applications.

Event Centroiding Applied to Energy-Resolved Neutron Imaging at LANSCE

DOE PAGES

Borges, Nicholas; Losko, Adrian; Vogel, Sven

2018-02-13

The energy-dependence of the neutron cross section provides vastly different contrast mechanisms than polychromatic neutron radiography if neutron energies can be selected for imaging applications. In recent years, energy-resolved neutron imaging (ERNI) with epi-thermal neutrons, utilizing neutron absorption resonances for contrast as well as for quantitative density measurements, was pioneered at the Flight Path 5 beam line at LANSCE and continues to be refined. In this work, we present event centroiding, i.e., the determination of the center-of-gravity of a detection event on an imaging detector to allow sub-pixel spatial resolution and apply it to the many frames collected for energy-resolvedmore » neutron imaging at a pulsed neutron source. While event centroiding was demonstrated at thermal neutron sources, it has not been applied to energy-resolved neutron imaging, where the energy resolution requires to be preserved, and we present a quantification of the possible resolution as a function of neutron energy. For the 55 μm pixel size of the detector used for this study, we found a resolution improvement from ~80 μm to ~22 μm using pixel centroiding while fully preserving the energy resolution.« less

Event Centroiding Applied to Energy-Resolved Neutron Imaging at LANSCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borges, Nicholas; Losko, Adrian; Vogel, Sven

The energy-dependence of the neutron cross section provides vastly different contrast mechanisms than polychromatic neutron radiography if neutron energies can be selected for imaging applications. In recent years, energy-resolved neutron imaging (ERNI) with epi-thermal neutrons, utilizing neutron absorption resonances for contrast as well as for quantitative density measurements, was pioneered at the Flight Path 5 beam line at LANSCE and continues to be refined. In this work, we present event centroiding, i.e., the determination of the center-of-gravity of a detection event on an imaging detector to allow sub-pixel spatial resolution and apply it to the many frames collected for energy-resolvedmore » neutron imaging at a pulsed neutron source. While event centroiding was demonstrated at thermal neutron sources, it has not been applied to energy-resolved neutron imaging, where the energy resolution requires to be preserved, and we present a quantification of the possible resolution as a function of neutron energy. For the 55 μm pixel size of the detector used for this study, we found a resolution improvement from ~80 μm to ~22 μm using pixel centroiding while fully preserving the energy resolution.« less

Synchrotron based planar imaging and digital tomosynthesis of breast and biopsy phantoms using a CMOS active pixel sensor.

PubMed

Szafraniec, Magdalena B; Konstantinidis, Anastasios C; Tromba, Giuliana; Dreossi, Diego; Vecchio, Sara; Rigon, Luigi; Sodini, Nicola; Naday, Steve; Gunn, Spencer; McArthur, Alan; Olivo, Alessandro

2015-03-01

The SYRMEP (SYnchrotron Radiation for MEdical Physics) beamline at Elettra is performing the first mammography study on human patients using free-space propagation phase contrast imaging. The stricter spatial resolution requirements of this method currently force the use of conventional films or specialized computed radiography (CR) systems. This also prevents the implementation of three-dimensional (3D) approaches. This paper explores the use of an X-ray detector based on complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology as a possible alternative, for acquisitions both in planar and tomosynthesis geometry. Results indicate higher quality of the images acquired with the synchrotron set-up in both geometries. This improvement can be partly ascribed to the use of parallel, collimated and monochromatic synchrotron radiation (resulting in scatter rejection, no penumbra-induced blurring and optimized X-ray energy), and partly to phase contrast effects. Even though the pixel size of the used detector is still too large - and thus suboptimal - for free-space propagation phase contrast imaging, a degree of phase-induced edge enhancement can clearly be observed in the images. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Development of depth encoding small animal PET detectors using dual-ended readout of pixelated scintillator arrays with SiPMs.

PubMed

Kuang, Zhonghua; Sang, Ziru; Wang, Xiaohui; Fu, Xin; Ren, Ning; Zhang, Xianming; Zheng, Yunfei; Yang, Qian; Hu, Zhanli; Du, Junwei; Liang, Dong; Liu, Xin; Zheng, Hairong; Yang, Yongfeng

2018-02-01

The performance of current small animal PET scanners is mainly limited by the detector performance and depth encoding detectors are required to develop PET scanner to simultaneously achieve high spatial resolution and high sensitivity. Among all depth encoding PET detector approaches, dual-ended readout detector has the advantage to achieve the highest depth of interaction (DOI) resolution and spatial resolution. Silicon photomultiplier (SiPM) is believed to be the photodetector of the future for PET detector due to its excellent properties as compared to the traditional photodetectors such as photomultiplier tube (PMT) and avalanche photodiode (APD). The purpose of this work is to develop high resolution depth encoding small animal PET detector using dual-ended readout of finely pixelated scintillator arrays with SiPMs. Four lutetium-yttrium oxyorthosilicate (LYSO) arrays with 11 × 11 crystals and 11.6 × 11.6 × 20 mm 3 outside dimension were made using ESR, Toray and BaSO 4 reflectors. The LYSO arrays were read out with Hamamatsu 4 × 4 SiPM arrays from both ends. The SiPM array has a pixel size of 3 × 3 mm 2 , 0.2 mm gap in between the pixels and a total active area of 12.6 × 12.6 mm 2 . The flood histograms, DOI resolution, energy resolution and timing resolution of the four detector modules were measured and compared. All crystals can be clearly resolved from the measured flood histograms of all four arrays. The BaSO 4 arrays provide the best and the ESR array provides the worst flood histograms. The DOI resolution obtained from the DOI profiles of the individual crystals of the four array is from 2.1 to 2.35 mm for events with E > 350 keV. The DOI ratio variation among crystals is bigger for the BaSO 4 arrays as compared to both the ESR and Toray arrays. The BaSO 4 arrays provide worse detector based DOI resolution. The photopeak amplitude of the Toray array had the maximum change with depth, it provides the worst energy resolution of 21.3%. The photopeak amplitude of the BaSO 4 array with 80 μm reflector almost doesn't change with depth, it provides the best energy resolution of 12.9%. A maximum timing shift of 1.37 ns to 1.61 ns among the corner and the center crystals in the four arrays was obtained due to the use of resistor network readout. A crystal based timing resolution of 0.68 ns to 0.83 ns and a detector based timing resolution of 1.26 ns to 1.45 ns were obtained for the four detector modules. Four high resolution depth encoding small animal PET detectors were developed using dual-ended readout of pixelated scintillator arrays with SiPMs. The performance results show that those detectors can be used to build a small animal PET scanner to simultaneously achieve uniform high spatial resolution and high sensitivity. © 2017 American Association of Physicists in Medicine.

The bipolar silicon microstrip detector: A proposal for a novel precision tracking device

NASA Astrophysics Data System (ADS)

Horisberger, R.

1990-03-01

It is proposed to combine the technology of fully depleted silicon microstrip detectors fabricated on n doped high resistivity silicon with the concept of the bipolar transistor. This is done by adding a n ++ doped region inside the normal p + implanted region of the reverse biased p + n diode. Teh resulting structure has amplifying properties and is referred to as bipolar pixel transistor. The simplest readout scheme of a bipolar pixel array by an aluminium strip bus leads to the bipolar microstrip detector. The bipolar pixel structure is expected to give a better signal-to-noise performance for the detection of minimum ionizing charged particle tracks than the normal silicon diode strip detector and therefore should allow in future the fabrication of thinner silicon detectors for precision tracking.

Photon-counting array detectors for space and ground-based studies at ultraviolet and vacuum ultraviolet /VUV/ wavelengths

NASA Technical Reports Server (NTRS)

Timothy, J. G.; Bybee, R. L.

1981-01-01

The Multi-Anode Microchannel Arrays (MAMAs) are a family of photoelectric photon-counting array detectors, with formats as large as (256 x 1024)-pixels that can be operated in a windowless configuration at vacuum ultraviolet (VUV) and soft X-ray wavelengths or in a sealed configuration at ultraviolet and visible wavelengths. This paper describes the construction and modes of operation of (1 x 1024)-pixel and (24 x 1024)-pixel MAMA detector systems that are being built and qualified for use in sounding-rocket spectrometers for solar and stellar observations at wavelengths below 1300 A. The performance characteristics of the MAMA detectors at ultraviolet and VUV wavelengths are also described.

Cat-eye effect target recognition with single-pixel detectors

NASA Astrophysics Data System (ADS)

Jian, Weijian; Li, Li; Zhang, Xiaoyue

2015-12-01

A prototype of cat-eye effect target recognition with single-pixel detectors is proposed. Based on the framework of compressive sensing, it is possible to recognize cat-eye effect targets by projecting a series of known random patterns and measuring the backscattered light with three single-pixel detectors in different locations. The prototype only requires simpler, less expensive detectors and extends well beyond the visible spectrum. The simulations are accomplished to evaluate the feasibility of the proposed prototype. We compared our results to that obtained from conventional cat-eye effect target recognition methods using area array sensor. The experimental results show that this method is feasible and superior to the conventional method in dynamic and complicated backgrounds.

Performance verification of the CMS Phase-1 Upgrade Pixel detector

NASA Astrophysics Data System (ADS)

Veszpremi, V.

2017-12-01

The CMS tracker consists of two tracking systems utilizing semiconductor technology: the inner pixel and the outer strip detectors. The tracker detectors occupy the volume around the beam interaction region between 3 cm and 110 cm in radius and up to 280 cm along the beam axis. The pixel detector consists of 124 million pixels, corresponding to about 2 m 2 total area. It plays a vital role in the seeding of the track reconstruction algorithms and in the reconstruction of primary interactions and secondary decay vertices. It is surrounded by the strip tracker with 10 million read-out channels, corresponding to 200 m 2 total area. The tracker is operated in a high-occupancy and high-radiation environment established by particle collisions in the LHC . The current strip detector continues to perform very well. The pixel detector that has been used in Run 1 and in the first half of Run 2 was, however, replaced with the so-called Phase-1 Upgrade detector. The new system is better suited to match the increased instantaneous luminosity the LHC would reach before 2023. It was built to operate at an instantaneous luminosity of around 2×1034 cm-2s-1. The detector's new layout has an additional inner layer with respect to the previous one; it allows for more efficient tracking with smaller fake rate at higher event pile-up. The paper focuses on the first results obtained during the commissioning of the new detector. It also includes challenges faced during the first data taking to reach the optimal measurement efficiency. Details will be given on the performance at high occupancy with respect to observables such as data-rate, hit reconstruction efficiency, and resolution.

Development and Production of Array Barrier Detectors at SCD

NASA Astrophysics Data System (ADS)

Klipstein, P. C.; Avnon, E.; Benny, Y.; Berkowicz, E.; Cohen, Y.; Dobromislin, R.; Fraenkel, R.; Gershon, G.; Glozman, A.; Hojman, E.; Ilan, E.; Karni, Y.; Klin, O.; Kodriano, Y.; Krasovitsky, L.; Langof, L.; Lukomsky, I.; Nevo, I.; Nitzani, M.; Pivnik, I.; Rappaport, N.; Rosenberg, O.; Shtrichman, I.; Shkedy, L.; Snapi, N.; Talmor, R.; Tessler, R.; Weiss, E.; Tuito, A.

2017-09-01

XB n or XB p barrier detectors exhibit diffusion-limited dark currents comparable with mercury cadmium telluride Rule-07 and high quantum efficiencies. In 2011, SemiConductor Devices (SCD) introduced "HOT Pelican D", a 640 × 512/15- μm pitch InAsSb/AlSbAs XB n mid-wave infrared (MWIR) detector with a 4.2- μm cut-off and an operating temperature of ˜150 K. Its low power (˜3 W), high pixel operability (>99.5%) and long mean time to failure make HOT Pelican D a highly reliable integrated detector-cooler product with a low size, weight and power. More recently, "HOT Hercules" was launched with a 1280 × 1024/15- μm format and similar advantages. A 3-megapixel, 10- μm pitch version ("HOT Blackbird") is currently completing development. For long-wave infrared applications, SCD's 640 × 512/15- μm pitch "Pelican-D LW" XB p type II superlattice (T2SL) detector has a ˜9.3- μm cut-off wavelength. The detector contains InAs/GaSb and InAs/AlSb T2SLs, and is fabricated into focal plane array (FPA) detectors using standard production processes including hybridization to a digital silicon read-out integrated circuit (ROIC), glue underfill and substrate thinning. The ROIC has been designed so that the complete detector closely follows the interfaces of SCD's MWIR Pelican-D detector family. The Pelican-D LW FPA has a quantum efficiency of ˜50%, and operates at 77 K with a pixel operability of >99% and noise equivalent temperature difference of 13 mK at 30 Hz and F/2.7.

Imaging tissues for biomedical research using the high-resolution micro-tomography system nanotom® m

NASA Astrophysics Data System (ADS)

Deyhle, Hans; Schulz, Georg; Khimchenko, Anna; Bikis, Christos; Hieber, Simone E.; Jaquiery, Claude; Kunz, Christoph; Müller-Gerbl, Magdalena; Höchel, Sebastian; Saxer, Till; Stalder, Anja K.; Ilgenstein, Bernd; Beckmann, Felix; Thalmann, Peter; Buscema, Marzia; Rohr, Nadja; Holme, Margaret N.; Müller, Bert

2016-10-01

Micro computed tomography (mCT) is well established in virtually all fields of biomedical research, allowing for the non-destructive volumetric visualization of tissue morphology. A variety of specimens can be investigated, ranging from soft to hard tissue to engineered structures like scaffolds. Similarly, the size of the objects of interest ranges from a fraction of a millimeter to several tens of centimeters. While synchrotron radiation-based μCT still offers unrivaled data quality, the ever-improving technology of cathodic tube-based machines offers a valuable and more accessible alternative. The Biomaterials Science Center of the University of Basel operates a nanotomOR m (phoenix|x-ray, GE Sensing and Inspection Technologies GmbH, Wunstorf, Germany), with a 180 kV source and a minimal spot size of about 0.9 μm. Through the adjustable focus-specimen and focus-detector distances, the effective pixel size can be adjusted from below 500 nm to about 80 μm. On the high-resolution side, it is for example possible to visualize the tubular network in sub-millimeter thin dentin specimens. It is then possible to locally extract parameters such as tubule diameter, density, or alignment, giving information on cell movements during tooth formation. On the other side, with a horizontal shift of the 3,072 pixels x 2,400 pixels detector, specimens up to 35 cm in diameter can be scanned. It is possible, for example, to scan an entire human knee, albeit with inferior resolution. Lab source μCT machines are thus a powerful and flexible tool for the advancement of biomedical research, and a valuable and more accessible alternative to synchrotron radiation facilities.

Fabrication of Pop-up Detector Arrays on Si Wafers

NASA Technical Reports Server (NTRS)

Li, Mary J.; Allen, Christine A.; Gordon, Scott A.; Kuhn, Jonathan L.; Mott, David B.; Stahle, Caroline K.; Wang, Liqin L.

1999-01-01

High sensitivity is a basic requirement for a new generation of thermal detectors. To meet the requirement, close-packed, two-dimensional silicon detector arrays have been developed in NASA Goddard Space Flight Center. The goal of the task is to fabricate detector arrays configured with thermal detectors such as infrared bolometers and x-ray calorimeters to use in space fliGht missions. This paper focuses on the fabrication and the mechanical testing of detector arrays in a 0.2 mm pixel size, the smallest pop-up detectors being developed so far. These array structures, nicknamed "PUDS" for "Pop-Up Detectors", are fabricated on I pm thick, single-crystal, silicon membranes. Their designs have been refined so we can utilize the flexibility of thin silicon films by actually folding the silicon membranes to 90 degrees in order to obtain close-packed two-dimensional arrays. The PUD elements consist of a detector platform and two legs for mechanical support while also serving as electrical and thermal paths. Torsion bars and cantilevers connecting the detector platform to the legs provide additional flexures for strain relief. Using micro-electromechanical structure (MEMS) fabrication techniques, including photolithography, anisotropic chemical etching, reactive-ion etching, and laser dicing, we have fabricated PLTD detector arrays of fourteen designs with a variation of four parameters including cantilever length, torsion bar length and width, and leg length. Folding tests were conducted to test mechanical stress distribution for the array structures. We obtained folding yields and selected optimum design parameters to reach minimal stress levels. Computer simulation was also employed to verify mechanical behaviors of PUDs in the folding process. In addition, scanning electron microscopy was utilized to examine the flatness of detectors and the alignment of detector pixels in arrays. The fabrication of thermistors and heaters on the pop-up detectors is under way, preparing us for the next step of the experiment, the thermal test.

Optical design of a CubeSat-compatible imaging spectrometer

NASA Astrophysics Data System (ADS)

Mouroulis, Pantazis; Van Gorp, Byron; Green, Robert O.; Wilson, Daniel W.

2014-09-01

We describe a fast, uniform, low-polarization imaging spectrometer and telescope system that can be integrated in a 6U CubeSat. The spectral range is 350-1700 nm, with 5.7 nm sampling. The telescope and spectrometer operate at F/1.8. At 100 mm focal length, the telescope is the highest resolution form that can fit in the CubeSat frame without deployable mirrors. The field of view is 10° with 600 cross-track pixels. The spectrometer is designed for the new Teledyne CHROMA detector array with 30μm pixel size for maximizing throughput. The primary intended applications are coastal ocean and snow cover monitoring.

SU-G-IeP3-11: On the Utility of Pixel Variance to Characterize Noise for Image Receptors of Digital Radiography Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Finley, C; Dave, J

Purpose: To characterize noise for image receptors of digital radiography systems based on pixel variance. Methods: Nine calibrated digital image receptors associated with nine new portable digital radiography systems (Carestream Health, Inc., Rochester, NY) were used in this study. For each image receptor, thirteen images were acquired with RQA5 beam conditions for input detector air kerma ranging from 0 to 110 µGy, and linearized ‘For Processing’ images were extracted. Mean pixel value (MPV), standard deviation (SD) and relative noise (SD/MPV) were obtained from each image using ROI sizes varying from 2.5×2.5 to 20×20 mm{sup 2}. Variance (SD{sup 2}) was plottedmore » as a function of input detector air kerma and the coefficients of the quadratic fit were used to derive structured, quantum and electronic noise coefficients. Relative noise was also fitted as a function of input detector air kerma to identify noise sources. The fitting functions used least-squares approach. Results: The coefficient of variation values obtained using different ROI sizes was less than 1% for all the images. The structured, quantum and electronic coefficients obtained from the quadratic fit of variance (r>0.97) were 0.43±0.10, 3.95±0.27 and 2.89±0.74 (mean ± standard deviation), respectively, indicating that overall the quantum noise was the dominant noise source. However, for one system electronic noise coefficient (3.91) was greater than quantum noise coefficient (3.56) indicating electronic noise to be dominant. Using relative noise values, the power parameter of the fitting equation (|r|>0.93) showed a mean and standard deviation of 0.46±0.02. A 0.50 value for this power parameter indicates quantum noise to be the dominant noise source whereas values around 0.50 indicate presence of other noise sources. Conclusion: Characterizing noise from pixel variance assists in identifying contributions from various noise sources that, eventually, may affect image quality. This approach may be integrated during periodic quality assessments of digital image receptors.« less

Electron imaging with Medipix2 hybrid pixel detector.

PubMed

McMullan, G; Cattermole, D M; Chen, S; Henderson, R; Llopart, X; Summerfield, C; Tlustos, L; Faruqi, A R

2007-01-01

The electron imaging performance of Medipix2 is described. Medipix2 is a hybrid pixel detector composed of two layers. It has a sensor layer and a layer of readout electronics, in which each 55 microm x 55 microm pixel has upper and lower energy discrimination and MHz rate counting. The sensor layer consists of a 300 microm slab of pixellated monolithic silicon and this is bonded to the readout chip. Experimental measurement of the detective quantum efficiency, DQE(0) at 120 keV shows that it can reach approximately 85% independent of electron exposure, since the detector has zero noise, and the DQE(Nyquist) can reach approximately 35% of that expected for a perfect detector (4/pi(2)). Experimental measurement of the modulation transfer function (MTF) at Nyquist resolution for 120 keV electrons using a 60 keV lower energy threshold, yields a value that is 50% of that expected for a perfect detector (2/pi). Finally, Monte Carlo simulations of electron tracks and energy deposited in adjacent pixels have been performed and used to calculate expected values for the MTF and DQE as a function of the threshold energy. The good agreement between theory and experiment allows suggestions for further improvements to be made with confidence. The present detector is already very useful for experiments that require a high DQE at very low doses.

A CMOS pixel sensor prototype for the outer layers of linear collider vertex detector

NASA Astrophysics Data System (ADS)

Zhang, L.; Morel, F.; Hu-Guo, C.; Himmi, A.; Dorokhov, A.; Hu, Y.

2015-01-01

The International Linear Collider (ILC) expresses a stringent requirement for high precision vertex detectors (VXD). CMOS pixel sensors (CPS) have been considered as an option for the VXD of the International Large Detector (ILD), one of the detector concepts proposed for the ILC. MIMOSA-31 developed at IPHC-Strasbourg is the first CPS integrated with 4-bit column-level ADC for the outer layers of the VXD, adapted to an original concept minimizing the power consumption. It is composed of a matrix of 64 rows and 48 columns. The pixel concept combines in-pixel amplification with a correlated double sampling (CDS) operation in order to reduce the temporal noise and fixed pattern noise (FPN). At the bottom of the pixel array, each column is terminated with a self-triggered analog-to-digital converter (ADC). The ADC design was optimized for power saving at a sampling frequency of 6.25 MS/s. The prototype chip is fabricated in a 0.35 μm CMOS technology. This paper presents the details of the prototype chip and its test results.

Independent Testing of JWST Detector Prototypes

NASA Technical Reports Server (NTRS)

Figer, D. F.; Rauscher, B. J.; Regan, M. W.; Balleza, J.; Bergeron, L.; Morse, E.; Stockman, H. S.

2003-01-01

The Independent Detector Testing Laboratory (IDTL) is jointly operated by the Space Telescope Science Institute (STScI) and the Johns Hopkins University (MU), and is assisting the James Webb Space Telescope (JWST) mission in choosing and operating the best near-infrared detectors under a NASA Grant. The JWST is the centerpiece of the NASA Office of Space Science theme, the Astronomical Search for Origins, and the highest priority astronomy project for the next decade, according to the National Academy of Science. JWST will need to have the sensitivity to see the first light in the Universe to determine how galaxies formed in the web of dark matter that existed when the Universe was in its infancy (z approx. 10 - 20). To achieve this goal, the JWST Project must pursue an aggressive technology program and advance infrared detectors to performance levels beyond what is now possible. As part of this program, NASA has selected the IDTL to verify comparative performance between prototype JWST detectors developed by Rockwell Scientific (HgCdTe) and Raytheon (InSb). The IDTL is charged with obtaining an independent assessment of the ability of these two competing technologies to achieve the demanding specifications of the JWST program within the 0.6 - 5 approx. mum bandpass and in an ultra-low background (less than 0.01 e'/s/pixel) environment. We describe results from the JWST Detector Characterization Project that is being performed in the IDTL. In this project, we are measuring first-order detector parameters, i.e. dark current, read noise, QE, intra-pixel sensitivity, linearity, as functions of temperature, well size, and operational mode.

Independent Testing of JWST Detector Prototypes

NASA Technical Reports Server (NTRS)

Figer, Donald F.; Rauscher, Bernie J.; Regan, Michael W.; Morse, Ernie; Balleza, Jesus; Bergeron, Louis; Stockman, H. S.

2004-01-01

The Independent Detector Testing Laboratory (IDTL) is jointly operated by the Space Telescope Science Institute (STScI) and the Johns Hopkins University (JHU), and is assisting the James Webb Space Telescope (JWST) mission in choosing and operating the best near-infrared detectors. The JWST is the centerpiece of the NASA Office of Space Science theme, the Astronomical Search for Origins, and the highest priority astronomy project for the next decade, according to the National Academy of Science. JWST will need to have the sensitivity to see the first light in the Universe to determine how galaxies formed in the web of dark matter that existed when the Universe was in its infancy (z is approximately 10-20). To achieve this goal, the JWST Project must pursue an aggressive technology program and advance infrared detectors to performance levels beyond what is now possible. As part of this program, NASA has selected the IDTL to verify comparative performance between prototype JWST detectors developed by Rockwell Scientific (HgCdTe) and Raytheon (InSb). The IDTL is charged with obtaining an independent assessment of the ability of these two competing technologies to achieve the demanding specifications of the JWST program within the 0.6-5 micron bandpass and in an ultra-low background (less than 0.01 e(-)/s/pixel) environment. We describe results from the JWST Detector Characterization Project that is being performed in the LDTL. In this project, we are measuring first-order detector parameters, i.e. dark current, read noise, QE, intra-pixel sensitivity, linearity, as functions of temperature, well size, and operational mode.

Estimate of the neutron fields in ATLAS based on ATLAS-MPX detectors data

NASA Astrophysics Data System (ADS)

Bouchami, J.; Dallaire, F.; Gutiérrez, A.; Idarraga, J.; Král, V.; Leroy, C.; Picard, S.; Pospíšil, S.; Scallon, O.; Solc, J.; Suk, M.; Turecek, D.; Vykydal, Z.; Žemlièka, J.

2011-01-01

The ATLAS-MPX detectors are based on Medipix2 silicon devices designed by CERN for the detection of different types of radiation. These detectors are covered with converting layers of 6LiF and polyethylene (PE) to increase their sensitivity to thermal and fast neutrons, respectively. These devices allow the measurement of the composition and spectroscopic characteristics of the radiation field in ATLAS, particularly of neutrons. These detectors can operate in low or high preset energy threshold mode. The signature of particles interacting in a ATLAS-MPX detector at low threshold are clusters of adjacent pixels with different size and form depending on their type, energy and incidence angle. The classification of particles into different categories can be done using the geometrical parameters of these clusters. The Medipix analysis framework (MAFalda) — based on the ROOT application — allows the recognition of particle tracks left in ATLAS-MPX devices located at various positions in the ATLAS detector and cavern. The pattern recognition obtained from the application of MAFalda was configured to distinguish the response of neutrons from other radiation. The neutron response at low threshold is characterized by clusters of adjoining pixels (heavy tracks and heavy blobs) left by protons and heavy ions resulting from neutron interactions in the converting layers of the ATLAS-MPX devices. The neutron detection efficiency of ATLAS-MPX devices has been determined by the exposure of two detectors of reference to radionuclide sources of neutrons (252Cf and 241AmBe). With these results, an estimate of the neutrons fields produced at the devices locations during ATLAS operation was done.

The 150 ns detector project: Prototype preamplifier results

NASA Astrophysics Data System (ADS)

Warburton, W. K.; Russell, S. R.; Kleinfelder, Stuart A.

1994-08-01

The long-term goal of the 150 ns detector project is to develop a pixel area detector capable of 6 MHz frame rates (150 ns/frame). Our milestones toward this goal are: a single pixel, 1×256 1D and 8×8 2D detectors, 256×256 2D detectors and, finally, 1024 × 1024 2D detectors. The design strategy is to supply a complete electronics chain (resetting preamp, selectable gain amplifier, analog-to-digital converter (ADC), and memory) for each pixel. In the final detectors these will all be custom integrated circuits. The front-end preamplifiers are integrated first, since their design and performance are the most unusual and also critical to the project's success. Similarly, our early work is concentrated on devising and perfecting detector structures. In this paper we demonstrate the performance of prototypes of our integrated preamplifiers. While the final design will have 64 preamps to a chip, including a switchable gain stage, the prototypes were integrated 8 channels to a "Tiny Chip" and tested in 4 configurations (feedback capacitor Cf equal 2.5 or 4.0 pF, output directly or through a source follower). These devices have been tested thoroughly for reset settling times, gain, linearity, and electronic noise. They generally work as designed, being fast enough to easily integrate detector charge, settle, and reset in 150 ns. Gain and linearity appear to be acceptable. Current values of electronic noise, in double-sampling mode, are about twice the design goal of {2}/{3} of a single photon at 6 keV. We expect this figure to improve with the addition of the onboard amplifier stage and improved packaging. Our next test chip will include these improvements and allow testing with our first detector samples, which will be 1×256 (50 μm wide pixels) and 8×8 (1 mm 2 pixels) element detector on 1 mm thick silicon.

Modeling of Pixelated Detector in SPECT Pinhole Reconstruction.

PubMed

Feng, Bing; Zeng, Gengsheng L

2014-04-10

A challenge for the pixelated detector is that the detector response of a gamma-ray photon varies with the incident angle and the incident location within a crystal. The normalization map obtained by measuring the flood of a point-source at a large distance can lead to artifacts in reconstructed images. In this work, we investigated a method of generating normalization maps by ray-tracing through the pixelated detector based on the imaging geometry and the photo-peak energy for the specific isotope. The normalization is defined for each pinhole as the normalized detector response for a point-source placed at the focal point of the pinhole. Ray-tracing is used to generate the ideal flood image for a point-source. Each crystal pitch area on the back of the detector is divided into 60 × 60 sub-pixels. Lines are obtained by connecting between a point-source and the centers of sub-pixels inside each crystal pitch area. For each line ray-tracing starts from the entrance point at the detector face and ends at the center of a sub-pixel on the back of the detector. Only the attenuation by NaI(Tl) crystals along each ray is assumed to contribute directly to the flood image. The attenuation by the silica (SiO 2 ) reflector is also included in the ray-tracing. To calculate the normalization for a pinhole, we need to calculate the ideal flood for a point-source at 360 mm distance (where the point-source was placed for the regular flood measurement) and the ideal flood image for the point-source at the pinhole focal point, together with the flood measurement at 360 mm distance. The normalizations are incorporated in the iterative OSEM reconstruction as a component of the projection matrix. Applications to single-pinhole and multi-pinhole imaging showed that this method greatly reduced the reconstruction artifacts.

Simulation study of pixel detector charge digitization

NASA Astrophysics Data System (ADS)

Wang, Fuyue; Nachman, Benjamin; Sciveres, Maurice; Lawrence Berkeley National Laboratory Team

2017-01-01

Reconstruction of tracks from nearly overlapping particles, called Tracking in Dense Environments (TIDE), is an increasingly important component of many physics analyses at the Large Hadron Collider as signatures involving highly boosted jets are investigated. TIDE makes use of the charge distribution inside a pixel cluster to resolve tracks that share one of more of their pixel detector hits. In practice, the pixel charge is discretized using the Time-over-Threshold (ToT) technique. More charge information is better for discrimination, but more challenging for designing and operating the detector. A model of the silicon pixels has been developed in order to study the impact of the precision of the digitized charge distribution on distinguishing multi-particle clusters. The output of the GEANT4-based simulation is used to train neutral networks that predict the multiplicity and location of particles depositing energy inside one cluster of pixels. By studying the multi-particle cluster identification efficiency and position resolution, we quantify the trade-off between the number of ToT bits and low-level tracking inputs. As both ATLAS and CMS are designing upgraded detectors, this work provides guidance for the pixel module designs to meet TIDE needs. Work funded by the China Scholarship Council and the Office of High Energy Physics of the U.S. Department of Energy under contract DE-AC02-05CH11231.

DEPFET detectors for future electron-positron colliders

NASA Astrophysics Data System (ADS)

Marinas, C.

2015-11-01

The DEPFET Collaboration develops highly granular, ultra-thin pixel detectors for outstanding vertex reconstruction at future electron-positron collider experiments. A DEPFET sensor, by the integration of a field effect transistor on a fully depleted silicon bulk, provides simultaneous position sensitive detector capabilities and in pixel amplification. The characterization of the latest DEPFET prototypes has proven that a adequate signal-to-noise ratio and excellent single point resolution can be achieved for a sensor thickness of 50 micrometers. The close to final auxiliary ASICs have been produced and found to operate a DEPFET pixel detector of the latest generation with the required read-out speed. A complete detector concept is being developed for the Belle II experiment at the new Japanese super flavor factory. DEPFET is not only the technology of choice for the Belle II vertex detector, but also a prime candidate for the ILC. Therefore, in this contribution, the status of DEPFET R&D project is reviewed in the light of the requirements of the vertex detector at a future electron-positron collider.

A history of hybrid pixel detectors, from high energy physics to medical imaging

NASA Astrophysics Data System (ADS)

Delpierre, P.

2014-05-01

The aim of this paper is to describe the development of hybrid pixel detectors from the origin to the application on medical imaging. We are going to recall the need for fast 2D detectors in the high energy physics experiments and to follow the different pixel electronic circuits created to satisfy this demand. The adaptation of these circuits for X-rays will be presented as well as their industrialization. Today, a number of applications are open for these cameras, particularly for biomedical imaging applications. Some developments for clinical CT will also be shown.

Improvement of the energy resolution of pixelated CdTe detectors for applications in 0νββ searches

NASA Astrophysics Data System (ADS)

Gleixner, T.; Anton, G.; Filipenko, M.; Seller, P.; Veale, M. C.; Wilson, M. D.; Zang, A.; Michel, T.

2015-07-01

Experiments trying to detect 0νββ are very challenging. Their requirements include a good energy resolution and a good detection efficiency. With current fine pixelated CdTe detectors there is a trade off between the energy resolution and the detection efficiency, which limits their performance. It will be shown with simulations that this problem can be mostly negated by analysing the cathode signal which increases the optimal sensor thickness. We will compare different types of fine pixelated CdTe detectors (Timepix, Dosepix, HEXITEC) from this point of view.

Coloured computational imaging with single-pixel detectors based on a 2D discrete cosine transform

NASA Astrophysics Data System (ADS)

Liu, Bao-Lei; Yang, Zhao-Hua; Liu, Xia; Wu, Ling-An

2017-02-01

We propose and demonstrate a computational imaging technique that uses structured illumination based on a two-dimensional discrete cosine transform to perform imaging with a single-pixel detector. A scene is illuminated by a projector with two sets of orthogonal patterns, then by applying an inverse cosine transform to the spectra obtained from the single-pixel detector a full-colour image is retrieved. This technique can retrieve an image from sub-Nyquist measurements, and the background noise is easily cancelled to give excellent image quality. Moreover, the experimental set-up is very simple.

Microscope mode secondary ion mass spectrometry imaging with a Timepix detector.

PubMed

Kiss, Andras; Jungmann, Julia H; Smith, Donald F; Heeren, Ron M A

2013-01-01

In-vacuum active pixel detectors enable high sensitivity, highly parallel time- and space-resolved detection of ions from complex surfaces. For the first time, a Timepix detector assembly was combined with a secondary ion mass spectrometer for microscope mode secondary ion mass spectrometry (SIMS) imaging. Time resolved images from various benchmark samples demonstrate the imaging capabilities of the detector system. The main advantages of the active pixel detector are the higher signal-to-noise ratio and parallel acquisition of arrival time and position. Microscope mode SIMS imaging of biomolecules is demonstrated from tissue sections with the Timepix detector.

Detector Having A Transmission Grating Beam Splitter For Multi-Wavelength Sample Analysis.

DOEpatents

Liu, Changsheng; Li, Qingbo

2000-09-12

A detector for DNA sample identification is provided with a transmission grating beam splitter (TGBS). The TGBS split fluoresced light from a tagged DNA sample into 0th order and a 1st order components, both of which are detected on a two-dimensional detector array of a CCD camera. The 0th and 1st order components are detected along a column of pixels in the detector array, and are spaced apart from one another. The DNA samples are tagged with four fluorescent dyes, one dye specific for each nucleotide, and all four dyes responding in slightly different manner to the same monochromatic excitation signal. The TGBS splits fluoresced incoming light into 0th and 1st order components, which are then spread out among a number of pixels in the detector array. The 1st component of this light is received by pixels whose position relative to the 0th order component depends on the frequency of fluorescence. Thus, the position at which signal energy is detected on the array is indicative of the particular dye, and therefore, the corresponding nucleotide tagged by that dye. Monitoring signal energy at the 0th order pixel and selected 1st order pixels, provides a set of data from which one may then identify the particular nucleotide.

Detector Having A Transmission Grating Beam Splitter For Multi-Wavelength.

DOEpatents

Liu, Changsheng; Li, Qingbo (State College, PA

1999-12-07

A detector for DNA sample identification is provided with a transmission grating beam splitter (TGBS). The TGBS split fluoresced light from a tagged DNA sample into 0th order and a 1st order components, both of which are detected on a two-dimensional detector array of a CCD camera. The 0th and 1st order components are detected along a column of pixels in the detector array, and are spaced apart from one another. The DNA samples are tagged with four fluorescent dyes, one dye specific for each nucleotide, and all four dyes responding in slightly different manner to the same monochromatic excitation signal. The TGBS splits fluoresced incoming light into 0th and 1st order components, which are then spread out among a number of pixels in the detector array. The 1st component of this light is received by pixels whose position relative to the 0th order component depends on the frequency of fluorescence. Thus, the position at which signal energy is detected on the array is indicative of the particular dye, and therefore, the corresponding nucleotide tagged by that dye. Monitoring signal energy at the 0th order pixel and selected 1st order pixels, provides a set of data from which one may then identify the particular nucleotide.

Performance simulation of an x-ray detector for spectral CT with combined Si and Cd[Zn]Te detection layers

NASA Astrophysics Data System (ADS)

Herrmann, Christoph; Engel, Klaus-Jürgen; Wiegert, Jens

2010-12-01

The most obvious problem in obtaining spectral information with energy-resolving photon counting detectors in clinical computed tomography (CT) is the huge x-ray flux present in conventional CT systems. At high tube voltages (e.g. 140 kVp), despite the beam shaper, this flux can be close to 109 Mcps mm-2 in the direct beam or in regions behind the object, which are close to the direct beam. Without accepting the drawbacks of truncated reconstruction, i.e. estimating missing direct-beam projection data, a photon-counting energy-resolving detector has to be able to deal with such high count rates. Sub-structuring pixels into sub-pixels is not enough to reduce the count rate per pixel to values that today's direct converting Cd[Zn]Te material can cope with (<=10 Mcps in an optimistic view). Below 300 µm pixel pitch, x-ray cross-talk (Compton scatter and K-escape) and the effect of charge diffusion between pixels are problematic. By organising the detector in several different layers, the count rate can be further reduced. However this alone does not limit the count rates to the required level, since the high stopping power of the material becomes a disadvantage in the layered approach: a simple absorption calculation for 300 µm pixel pitch shows that the required layer thickness of below 10 Mcps/pixel for the top layers in the direct beam is significantly below 100 µm. In a horizontal multi-layer detector, such thin layers are very difficult to manufacture due to the brittleness of Cd[Zn]Te. In a vertical configuration (also called edge-on illumination (Ludqvist et al 2001 IEEE Trans. Nucl. Sci. 48 1530-6, Roessl et al 2008 IEEE NSS-MIC-RTSD 2008, Conf. Rec. Talk NM2-3)), bonding of the readout electronics (with pixel pitches below 100 µm) is not straightforward although it has already been done successfully (Pellegrini et al 2004 IEEE NSS MIC 2004 pp 2104-9). Obviously, for the top detector layers, materials with lower stopping power would be advantageous. The possible choices are, however, quite limited, since only 'mature' materials, which operate at room temperature and can be manufactured reliably should reasonably be considered. Since GaAs is still known to cause reliability problems, the simplest choice is Si, however with the drawback of strong Compton scatter which can cause considerable inter-pixel cross-talk. To investigate the potential and the problems of Si in a multi-layer detector, in this paper the combination of top detector layers made of Si with lower layers made of Cd[Zn]Te is studied by using Monte Carlo simulated detector responses. It is found that the inter-pixel cross-talk due to Compton scatter is indeed very high; however, with an appropriate cross-talk correction scheme, which is also described, the negative effects of cross-talk are shown to be removed to a very large extent.

Efficient phase contrast imaging in STEM using a pixelated detector. Part 1: Experimental demonstration at atomic resolution

DOE PAGES

Pennycook, Timothy J.; Lupini, Andrew R.; Yang, Hao; ...

2014-10-15

In this paper, we demonstrate a method to achieve high efficiency phase contrast imaging in aberration corrected scanning transmission electron microscopy (STEM) with a pixelated detector. The pixelated detector is used to record the Ronchigram as a function of probe position which is then analyzed with ptychography. Ptychography has previously been used to provide super-resolution beyond the diffraction limit of the optics, alongside numerically correcting for spherical aberration. Here we rely on a hardware aberration corrector to eliminate aberrations, but use the pixelated detector data set to utilize the largest possible volume of Fourier space to create high efficiency phasemore » contrast images. The use of ptychography to diagnose the effects of chromatic aberration is also demonstrated. In conclusion, the four dimensional dataset is used to compare different bright field detector configurations from the same scan for a sample of bilayer graphene. Our method of high efficiency ptychography produces the clearest images, while annular bright field produces almost no contrast for an in-focus aberration-corrected probe.« less

Computational imaging with a single-pixel detector and a consumer video projector

NASA Astrophysics Data System (ADS)

Sych, D.; Aksenov, M.

2018-02-01

Single-pixel imaging is a novel rapidly developing imaging technique that employs spatially structured illumination and a single-pixel detector. In this work, we experimentally demonstrate a fully operating modular single-pixel imaging system. Light patterns in our setup are created with help of a computer-controlled digital micromirror device from a consumer video projector. We investigate how different working modes and settings of the projector affect the quality of reconstructed images. We develop several image reconstruction algorithms and compare their performance for real imaging. Also, we discuss the potential use of the single-pixel imaging system for quantum applications.

Novel Hybrid CMOS X-ray Detector Developments for Future Large Area and High Resolution X-ray Astronomy Missions

NASA Astrophysics Data System (ADS)

Falcone, Abe

In the coming years, X-ray astronomy will require new soft X-ray detectors that can be read very quickly with low noise and can achieve small pixel sizes over a moderately large focal plane area. These requirements will be present for a variety of X-ray missions that will attempt to address science that was highly ranked by the Decadal Review, including missions with science that over-laps with that of IXO and ATHENA, as well as other missions addressing science topics beyond those of IXO and ATHENA. An X-ray Surveyor mission was recently endorsed by the NASA long term planning document entitled "Enduring Quests, Daring Visions," and a detailed description of one possible realization of such a mission has been referred to as SMART-X, which was described in a recent NASA RFI response. This provides an example of a future mission concept with these requirements since it has high X-ray throughput and excellent spatial resolution. We propose to continue to modify current active pixel sensor designs, in particular the hybrid CMOS detectors that we have been working with for several years, and implement new in-pixel technologies that will allow us to achieve these ambitious and realistic requirements on a timeline that will make them available to upcoming X-ray missions. This proposal is a continuation of our program that has been working on these developments for the past several years.

A low-noise wide-dynamic-range event-driven detector using SOI pixel technology for high-energy particle imaging

NASA Astrophysics Data System (ADS)

Shrestha, Sumeet; Kamehama, Hiroki; Kawahito, Shoji; Yasutomi, Keita; Kagawa, Keiichiro; Takeda, Ayaki; Tsuru, Takeshi Go; Arai, Yasuo

2015-08-01

This paper presents a low-noise wide-dynamic-range pixel design for a high-energy particle detector in astronomical applications. A silicon on insulator (SOI) based detector is used for the detection of wide energy range of high energy particles (mainly for X-ray). The sensor has a thin layer of SOI CMOS readout circuitry and a thick layer of high-resistivity detector vertically stacked in a single chip. Pixel circuits are divided into two parts; signal sensing circuit and event detection circuit. The event detection circuit consisting of a comparator and logic circuits which detect the incidence of high energy particle categorizes the incident photon it into two energy groups using an appropriate energy threshold and generate a two-bit code for an event and energy level. The code for energy level is then used for selection of the gain of the in-pixel amplifier for the detected signal, providing a function of high-dynamic-range signal measurement. The two-bit code for the event and energy level is scanned in the event scanning block and the signals from the hit pixels only are read out. The variable-gain in-pixel amplifier uses a continuous integrator and integration-time control for the variable gain. The proposed design allows the small signal detection and wide dynamic range due to the adaptive gain technique and capability of correlated double sampling (CDS) technique of kTC noise canceling of the charge detector.

Experience from the construction and operation of the STAR PXL detector

NASA Astrophysics Data System (ADS)

Greiner, L.; Anderssen, E. C.; Contin, G.; Schambach, J.; Silber, J.; Stezelberger, T.; Sun, X.; Szelezniak, M.; Vu, C.; Wieman, H. H.; Woodmansee, S.

2015-04-01

A new silicon based vertex detector called the Heavy Flavor Tracker (HFT) was installed at the Soleniodal Tracker At RHIC (STAR) experiment for the Relativistic Heavy Ion Collider (RHIC) 2014 heavy ion run to improve the vertex resolution and extend the measurement capabilities of STAR in the heavy flavor domain. The HFT consists of four concentric cylinders around the STAR interaction point composed of three different silicon detector technologies based on strips, pads and for the first time in an accelerator experiment CMOS monolithic active pixels (MAPS) . The two innermost layers at a radius of 2.8 cm and 8 cm from the beam line are constructed with 400 high resolution MAPS sensors arranged in 10-sensor ladders mounted on 10 thin carbon fiber sectors giving a total silicon area of 0.16 m2. Each sensor consists of a pixel array of nearly 1 million pixels with a pitch of 20.7 μm with column-level discriminators, zero-suppression circuitry and output buffer memory integrated into one silicon die with a sensitive area of ~ 3.8 cm2. The pixel (PXL) detector has a low power dissipation of 170 mW/cm2, which allows air cooling. This results in a global material budget of 0.5% radiation length per layer for detector used in this run. A novel mechanical approach to detector insertion allows for the installation and integration of the pixel sub detector within a 12 hour period during an on-going STAR run. The detector specifications, experience from the construction and operation, lessons learned and initial measurements of the PXL performance in the 200 GeV Au-Au run will be presented.

Advanced testing of the DEPFET minimatrix particle detector

NASA Astrophysics Data System (ADS)

Andricek, L.; Kodyš, P.; Koffmane, C.; Ninkovic, J.; Oswald, C.; Richter, R.; Ritter, A.; Rummel, S.; Scheirich, J.; Wassatsch, A.

2012-01-01

The DEPFET (DEPleted Field Effect Transistor) is an active pixel particle detector with a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) integrated in each pixel, providing first amplification stage of readout electronics. Excellent signal over noise performance is gained this way. The DEPFET sensor will be used as a vertex detector in the Belle II experiment at SuperKEKB, electron-positron collider in Japan. The vertex detector will be composed of two layers of pixel detectors (DEPFET) and four layers of strip detectors. The DEPFET sensor requires switching and current readout circuits for its operation. These circuits have been designed as ASICs (Application Specific Integrated Circuits) in several different versions, but they provide insufficient flexibility for precise detector testing. Therefore, a test system with a flexible control cycle range and minimal noise has been designed for testing and characterizing of small detector prototypes (Minimatrices). Sensors with different design layouts and thicknesses are produced in order to evaluate and select the one with the best performance for the Belle II application. Description of the test system as well as measurement results are presented.

FITPix COMBO—Timepix detector with integrated analog signal spectrometric readout

NASA Astrophysics Data System (ADS)

Holik, M.; Kraus, V.; Georgiev, V.; Granja, C.

2016-02-01

The hybrid semiconductor pixel detector Timepix has proven a powerful tool in radiation detection and imaging. Energy loss and directional sensitivity as well as particle type resolving power are possible by high resolution particle tracking and per-pixel energy and quantum-counting capability. The spectrometric resolving power of the detector can be further enhanced by analyzing the analog signal of the detector common sensor electrode (also called back-side pulse). In this work we present a new compact readout interface, based on the FITPix readout architecture, extended with integrated analog electronics for the detector's common sensor signal. Integrating simultaneous operation of the digital per-pixel information with the common sensor (called also back-side electrode) analog pulse processing circuitry into one device enhances the detector capabilities and opens new applications. Thanks to noise suppression and built-in electromagnetic interference shielding the common hardware platform enables parallel analog signal spectroscopy on the back side pulse signal with full operation and read-out of the pixelated digital part, the noise level is 600 keV and spectrometric resolution around 100 keV for 5.5 MeV alpha particles. Self-triggering is implemented with delay of few tens of ns making use of adjustable low-energy threshold of the particle analog signal amplitude. The digital pixelated full frame can be thus triggered and recorded together with the common sensor analog signal. The waveform, which is sampled with frequency 100 MHz, can be recorded in adjustable time window including time prior to the trigger level. An integrated software tool provides control, on-line display and read-out of both analog and digital channels. Both the pixelated digital record and the analog waveform are synchronized and written out by common time stamp.

MAPS development for the ALICE ITS upgrade

NASA Astrophysics Data System (ADS)

Yang, P.; Aglieri, G.; Cavicchioli, C.; Chalmet, P. L.; Chanlek, N.; Collu, A.; Gao, C.; Hillemanns, H.; Junique, A.; Kofarago, M.; Keil, M.; Kugathasan, T.; Kim, D.; Kim, J.; Lattuca, A.; Marin Tobon, C. A.; Marras, D.; Mager, M.; Martinengo, P.; Mazza, G.; Mugnier, H.; Musa, L.; Puggioni, C.; Rousset, J.; Reidt, F.; Riedler, P.; Snoeys, W.; Siddhanta, S.; Usai, G.; van Hoorne, J. W.; Yi, J.

2015-03-01

Monolithic Active Pixel Sensors (MAPS) offer the possibility to build pixel detectors and tracking layers with high spatial resolution and low material budget in commercial CMOS processes. Significant progress has been made in the field of MAPS in recent years, and they are now considered for the upgrades of the LHC experiments. This contribution will focus on MAPS detectors developed for the ALICE Inner Tracking System (ITS) upgrade and manufactured in the TowerJazz 180 nm CMOS imaging sensor process on wafers with a high resistivity epitaxial layer. Several sensor chip prototypes have been developed and produced to optimise both charge collection and readout circuitry. The chips have been characterised using electrical measurements, radioactive sources and particle beams. The tests indicate that the sensors satisfy the ALICE requirements and first prototypes with the final size of 1.5 × 3 cm2 have been produced in the first half of 2014. This contribution summarises the characterisation measurements and presents first results from the full-scale chips.

Digital radiography using amorphous selenium: photoconductively activated switch (PAS) readout system.

PubMed

Reznik, Nikita; Komljenovic, Philip T; Germann, Stephen; Rowlands, John A

2008-03-01

A new amorphous selenium (a-Se) digital radiography detector is introduced. The proposed detector generates a charge image in the a-Se layer in a conventional manner, which is stored on electrode pixels at the surface of the a-Se layer. A novel method, called photoconductively activated switch (PAS), is used to read out the latent x-ray charge image. The PAS readout method uses lateral photoconduction at the a-Se surface which is a revolutionary modification of the bulk photoinduced discharge (PID) methods. The PAS method addresses and eliminates the fundamental weaknesses of the PID methods--long readout times and high readout noise--while maintaining the structural simplicity and high resolution for which PID optical readout systems are noted. The photoconduction properties of the a-Se surface were investigated and the geometrical design for the electrode pixels for a PAS radiography system was determined. This design was implemented in a single pixel PAS evaluation system. The results show that the PAS x-ray induced output charge signal was reproducible and depended linearly on the x-ray exposure in the diagnostic exposure range. Furthermore, the readout was reasonably rapid (10 ms for pixel discharge). The proposed detector allows readout of half a pixel row at a time (odd pixels followed by even pixels), thus permitting the readout of a complete image in 30 s for a 40 cm x 40 cm detector with the potential of reducing that time by using greater readout light intensity. This demonstrates that a-Se based x-ray detectors using photoconductively activated switches could form a basis for a practical integrated digital radiography system.

Modeling and analysis of hybrid pixel detector deficiencies for scientific applications

NASA Astrophysics Data System (ADS)

Fahim, Farah; Deptuch, Grzegorz W.; Hoff, James R.; Mohseni, Hooman

2015-08-01

Semiconductor hybrid pixel detectors often consist of a pixellated sensor layer bump bonded to a matching pixelated readout integrated circuit (ROIC). The sensor can range from high resistivity Si to III-V materials, whereas a Si CMOS process is typically used to manufacture the ROIC. Independent, device physics and electronic design automation (EDA) tools are used to determine sensor characteristics and verify functional performance of ROICs respectively with significantly different solvers. Some physics solvers provide the capability of transferring data to the EDA tool. However, single pixel transient simulations are either not feasible due to convergence difficulties or are prohibitively long. A simplified sensor model, which includes a current pulse in parallel with detector equivalent capacitor, is often used; even then, spice type top-level (entire array) simulations range from days to weeks. In order to analyze detector deficiencies for a particular scientific application, accurately defined transient behavioral models of all the functional blocks are required. Furthermore, various simulations, such as transient, noise, Monte Carlo, inter-pixel effects, etc. of the entire array need to be performed within a reasonable time frame without trading off accuracy. The sensor and the analog front-end can be modeling using a real number modeling language, as complex mathematical functions or detailed data can be saved to text files, for further top-level digital simulations. Parasitically aware digital timing is extracted in a standard delay format (sdf) from the pixel digital back-end layout as well as the periphery of the ROIC. For any given input, detector level worst-case and best-case simulations are performed using a Verilog simulation environment to determine the output. Each top-level transient simulation takes no more than 10-15 minutes. The impact of changing key parameters such as sensor Poissonian shot noise, analog front-end bandwidth, jitter due to clock distribution etc. can be accurately analyzed to determine ROIC architectural viability and bottlenecks. Hence the impact of the detector parameters on the scientific application can be studied.

Improved IR detectors to swap heavy systems for SWaP

NASA Astrophysics Data System (ADS)

Manissadjian, Alain; Rubaldo, Laurent; Rebeil, Yann; Kerlain, Alexandre; Brellier, Delphine; Mollard, Laurent

2012-06-01

Cooled IR technologies are challenged for answering new system needs like the compactness and the reduction of cryopower which is a key feature for the SWaP (Size, Weight and Power) requirements. Over the last years, SOFRADIR has improved its HgCdTe technology, with effect on dark current reduction, opening the way for High Operating Temperature (HOT) systems that can get rid of the 80K temperature constraint, and therefore releases the Stirling cooler engine power consumption. Performances of the 640×512 15μm pitch LW detector working above 100K will be presented. A compact 640×512 15μm pitch MW detector presenting high EO performance above 130K with cut-off wavelength above 5.0μm has been developed. Its different performances with respect to the market requirements for SWaP will be discussed. High performance compact systems will make no compromise on detector resolution. The pixel pitch reduction is the answer for resolution enhancement with size reduction. We will therefore also discuss the ongoing developments and market needs for SWaP systems.

Development of an ultrahigh-resolution Si-PM-based dual-head GAGG coincidence imaging system

NASA Astrophysics Data System (ADS)

Yamamoto, Seiichi; Watabe, Hiroshi; Kanai, Yasukazu; Kato, Katsuhiko; Hatazawa, Jun

2013-03-01

A silicon photomultiplier (Si-PM) is a promising photodetector for high resolution PET systems due to its small channel size and high gain. Using Si-PMs, it will be possible to develop a high resolution imaging systems. For this purpose, we developed a small field-of-view (FOV) ultrahigh-resolution Si-PM-based dual-head coincidence imaging system for small animals and plant research. A new scintillator, Ce doped Gd3Al12Ga3O12 (GAGG), was selected because of its high light output and its emission wavelength matched with the Si-PM arrays and contained no radioactivity. Each coincidence imaging block detector consists of 0.5×0.5×5 mm3 GAGG pixels combined with a 0.1-mm thick reflector to form a 20×17 matrix that was optically coupled to a Si-PM array (Hamamatsu MPPC S11064-050P) with a 1.5-mm thick light guide. The GAGG block size was 12.0×10.2 mm2. Two GAGG block detectors were positioned face to face and set on a flexible arm based detector stand. All 0.5 mm GAGG pixels in the block detectors were clearly resolved in the 2-dimensional position histogram. The energy resolution was 14.4% FWHM for the Cs-137 gamma ray. The spatial resolution was 0.7 mm FWHM measured using a 0.25 mm diameter Na-22 point source. Small animal and plant images were successfully obtained. We conclude that our developed ultrahigh-resolution Si-PM-based dual-head coincidence imaging system is promising for small animal and plant imaging research.

Image quality of a pixellated GaAs X-ray detector

NASA Astrophysics Data System (ADS)

Sun, G. C.; Makham, S.; Bourgoin, J. C.; Mauger, A.

2007-02-01

X-ray detection requires materials with large atomic numbers Z in order to absorb the radiation efficiently. In case of X-ray imaging, fluorescence is a limiting factor for the spatial resolution and contrast at energies above the kα threshold. Since both the energy and yield of the fluorescence of a given material increase with the atomic number, there is an optimum value of Z. GaAs, which can now be epitaxially grown as self-supported thick layers to fulfil the requirements for imaging (good homogeneity of the electronic properties) corresponds to this optimum. Image performances obtained with this material are evaluated in terms of line spread function and modulation transfer function, and a comparison with CsI is made. We evaluate the image contrast obtained for a given object contrast with GaAs and CsI detectors, in the photon energy range of medical applications. Finally, we discuss the minimum object size, which can be detected by these detectors in of mammography conditions. This demonstrates that an object of a given size can be detected using a GaAs detector with a dose at least 100 times lower than using a CsI detector.

Novel Hyperspectral Anomaly Detection Methods Based on Unsupervised Nearest Regularized Subspace

NASA Astrophysics Data System (ADS)

Hou, Z.; Chen, Y.; Tan, K.; Du, P.

2018-04-01

Anomaly detection has been of great interest in hyperspectral imagery analysis. Most conventional anomaly detectors merely take advantage of spectral and spatial information within neighboring pixels. In this paper, two methods of Unsupervised Nearest Regularized Subspace-based with Outlier Removal Anomaly Detector (UNRSORAD) and Local Summation UNRSORAD (LSUNRSORAD) are proposed, which are based on the concept that each pixel in background can be approximately represented by its spatial neighborhoods, while anomalies cannot. Using a dual window, an approximation of each testing pixel is a representation of surrounding data via a linear combination. The existence of outliers in the dual window will affect detection accuracy. Proposed detectors remove outlier pixels that are significantly different from majority of pixels. In order to make full use of various local spatial distributions information with the neighboring pixels of the pixels under test, we take the local summation dual-window sliding strategy. The residual image is constituted by subtracting the predicted background from the original hyperspectral imagery, and anomalies can be detected in the residual image. Experimental results show that the proposed methods have greatly improved the detection accuracy compared with other traditional detection method.

Studies on a 300 k pixel detector telescope

NASA Astrophysics Data System (ADS)

Middelkamp, Peter; Antinori, F.; Barberis, D.; Becks, K. H.; Beker, H.; Beusch, W.; Burger, P.; Campbell, M.; Cantatore, E.; Catanesi, M. G.; Chesi, E.; Darbo, G.; D'Auria, S.; Davia, C.; di Bari, D.; di Liberto, S.; Elia, D.; Gys, T.; Heijne, E. H. M.; Helstrup, H.; Jacholkowski, A.; Jæger, J. J.; Jakubek, J.; Jarron, P.; Klempt, W.; Krummenacher, F.; Knudson, K.; Kralik, I.; Kubasta, J.; Lasalle, J. C.; Leitner, R.; Lemeilleur, F.; Lenti, V.; Letheren, M.; Lopez, L.; Loukas, D.; Luptak, M.; Martinengo, P.; Meddeler, G.; Meddi, F.; Morando, M.; Munns, A.; Pellegrini, F.; Pengg, F.; Pospisil, S.; Quercigh, E.; Ridky, J.; Rossi, L.; Safarik, K.; Scharfetter, L.; Segato, G.; Simone, S.; Smith, K.; Snoeys, W.; Vrba, V.

1996-02-01

Four silicon pixel detector planes are combined to form a tracking telescope in the lead ion experiment WA97 at CERN with 290 304 sensitive elements each of 75 μm by 500 μm area. An electronic pulse processing circuit is associated with each individual sensing element and the response for ionizing particles is binary with an adjustable threshold. The noise rate for a threshold of 6000 e- has been measured to be less than 10-10. The inefficient area due to malfunctioning pixels is 2.8% of the 120 cm2. Detector overlaps within one plane have been used to determine the alignment of the components of the plane itself, without need for track reconstruction using external detectors. It is the first time that such a big surface covered with active pixels has been used in a physics experiment. Some aspects concerning inclined particle tracks and time walk have been measured separately in a beam test at the CERN SPS H6 beam.

CdZnTe Image Detectors for Hard-X-Ray Telescopes

NASA Technical Reports Server (NTRS)

Chen, C. M. Hubert; Cook, Walter R.; Harrison, Fiona A.; Lin, Jiao Y. Y.; Mao, Peter H.; Schindler, Stephen M.

2005-01-01

Arrays of CdZnTe photodetectors and associated electronic circuitry have been built and tested in a continuing effort to develop focal-plane image sensor systems for hard-x-ray telescopes. Each array contains 24 by 44 pixels at a pitch of 498 m. The detector designs are optimized to obtain low power demand with high spectral resolution in the photon- energy range of 5 to 100 keV. More precisely, each detector array is a hybrid of a CdZnTe photodetector array and an application-specific integrated circuit (ASIC) containing an array of amplifiers in the same pixel pattern as that of the detectors. The array is fabricated on a single crystal of CdZnTe having dimensions of 23.6 by 12.9 by 2 mm. The detector-array cathode is a monolithic platinum contact. On the anode plane, the contact metal is patterned into the aforementioned pixel array, surrounded by a guard ring that is 1 mm wide on three sides and is 0.1 mm wide on the fourth side so that two such detector arrays can be placed side-by-side to form a roughly square sensor area with minimal dead area between them. Figure 1 shows two anode patterns. One pattern features larger pixel anode contacts, with a 30-m gap between them. The other pattern features smaller pixel anode contacts plus a contact for a shaping electrode in the form of a grid that separates all the pixels. In operation, the grid is held at a potential intermediate between the cathode and anode potentials to steer electric charges toward the anode in order to reduce the loss of charges in the inter-anode gaps. The CdZnTe photodetector array is mechanically and electrically connected to the ASIC (see Figure 2), either by use of indium bump bonds or by use of conductive epoxy bumps on the CdZnTe array joined to gold bumps on the ASIC. Hence, the output of each pixel detector is fed to its own amplifier chain.

Development of a novel direct X-ray detector using photoinduced discharge (PID) readout for digital radiography

NASA Astrophysics Data System (ADS)

Heo, D.; Jeon, S.; Kim, J.-S.; Kim, R. K.; Cha, B. K.; Moon, B. J.; Yoon, J.

2013-02-01

We developed a novel direct X-ray detector using photoinduced discharge (PID) readout for digital radiography. The pixel resolution is 512 × 512 with 200 μm pixel and the overall active dimensions of the X-ray imaging panel is 10.24 cm × 10.24 cm. The detector consists of an X-ray absorption layer of amorphous selenium, a charge accumulation layer of metal, and a PID readout layer of amorphous silicon. In particular, the charge accumulation is pixelated because image charges generated by X-ray should be stored pixel by pixel. Here the image charges, or holes, are recombined with electrons generated by the PID method. We used a 405 nm laser diode and cylindrical lens to make a line beam source with a width of 50 μm for PID readout, which generates charges for each pixel lines during the scan. We obtained spatial frequencies of about 1.0 lp/mm for the X-direction (lateral direction) and 0.9 lp/mm for the Y-direction (scanning direction) at 50% modulation transfer function.

Detection systems for mass spectrometry imaging: a perspective on novel developments with a focus on active pixel detectors.

PubMed

Jungmann, Julia H; Heeren, Ron M A

2013-01-15

Instrumental developments for imaging and individual particle detection for biomolecular mass spectrometry (imaging) and fundamental atomic and molecular physics studies are reviewed. Ion-counting detectors, array detection systems and high mass detectors for mass spectrometry (imaging) are treated. State-of-the-art detection systems for multi-dimensional ion, electron and photon detection are highlighted. Their application and performance in three different imaging modes--integrated, selected and spectral image detection--are described. Electro-optical and microchannel-plate-based systems are contrasted. The analytical capabilities of solid-state pixel detectors--both charge coupled device (CCD) and complementary metal oxide semiconductor (CMOS) chips--are introduced. The Medipix/Timepix detector family is described as an example of a CMOS hybrid active pixel sensor. Alternative imaging methods for particle detection and their potential for future applications are investigated. Copyright © 2012 John Wiley & Sons, Ltd.

Small-angle solution scattering using the mixed-mode pixel array detector.

PubMed

Koerner, Lucas J; Gillilan, Richard E; Green, Katherine S; Wang, Suntao; Gruner, Sol M

2011-03-01

Solution small-angle X-ray scattering (SAXS) measurements were obtained using a 128 × 128 pixel X-ray mixed-mode pixel array detector (MMPAD) with an 860 µs readout time. The MMPAD offers advantages for SAXS experiments: a pixel full-well of >2 × 10(7) 10 keV X-rays, a maximum flux rate of 10(8) X-rays pixel(-1) s(-1), and a sub-pixel point-spread function. Data from the MMPAD were quantitatively compared with data from a charge-coupled device (CCD) fiber-optically coupled to a phosphor screen. MMPAD solution SAXS data from lysozyme solutions were of equal or better quality than data captured by the CCD. The read-noise (normalized by pixel area) of the MMPAD was less than that of the CCD by an average factor of 3.0. Short sample-to-detector distances were required owing to the small MMPAD area (19.2 mm × 19.2 mm), and were revealed to be advantageous with respect to detector read-noise. As predicted by the Shannon sampling theory and confirmed by the acquisition of lysozyme solution SAXS curves, the MMPAD at short distances is capable of sufficiently sampling a solution SAXS curve for protein shape analysis. The readout speed of the MMPAD was demonstrated by continuously monitoring lysozyme sample evolution as radiation damage accumulated. These experiments prove that a small suitably configured MMPAD is appropriate for time-resolved solution scattering measurements.

Spectral X-Ray Diffraction using a 6 Megapixel Photon Counting Array Detector.

PubMed

Muir, Ryan D; Pogranichniy, Nicholas R; Muir, J Lewis; Sullivan, Shane Z; Battaile, Kevin P; Mulichak, Anne M; Toth, Scott J; Keefe, Lisa J; Simpson, Garth J

2015-03-12

Pixel-array array detectors allow single-photon counting to be performed on a massively parallel scale, with several million counting circuits and detectors in the array. Because the number of photoelectrons produced at the detector surface depends on the photon energy, these detectors offer the possibility of spectral imaging. In this work, a statistical model of the instrument response is used to calibrate the detector on a per-pixel basis. In turn, the calibrated sensor was used to perform separation of dual-energy diffraction measurements into two monochromatic images. Targeting applications include multi-wavelength diffraction to aid in protein structure determination and X-ray diffraction imaging.

Spectral x-ray diffraction using a 6 megapixel photon counting array detector

NASA Astrophysics Data System (ADS)

Muir, Ryan D.; Pogranichniy, Nicholas R.; Muir, J. Lewis; Sullivan, Shane Z.; Battaile, Kevin P.; Mulichak, Anne M.; Toth, Scott J.; Keefe, Lisa J.; Simpson, Garth J.

2015-03-01

Pixel-array array detectors allow single-photon counting to be performed on a massively parallel scale, with several million counting circuits and detectors in the array. Because the number of photoelectrons produced at the detector surface depends on the photon energy, these detectors offer the possibility of spectral imaging. In this work, a statistical model of the instrument response is used to calibrate the detector on a per-pixel basis. In turn, the calibrated sensor was used to perform separation of dual-energy diffraction measurements into two monochromatic images. Targeting applications include multi-wavelength diffraction to aid in protein structure determination and X-ray diffraction imaging.

Collection of holes in thick TlBr detectors at low temperature

NASA Astrophysics Data System (ADS)

Dönmez, Burçin; He, Zhong; Kim, Hadong; Cirignano, Leonard J.; Shah, Kanai S.

2012-10-01

A 3.5×3.5×4.6 mm3 thick TlBr detector with pixellated Au/Cr anodes made by Radiation Monitoring Devices Inc. was studied. The detector has a planar cathode and nine anode pixels surrounded by a guard ring. The pixel pitch is 1.0 mm. Digital pulse waveforms of preamplifier outputs were recorded using a multi-channel GaGe PCI digitizer board. Several experiments were carried out at -20 °C, with the detector under bias for over a month. An energy resolution of 1.7% FWHM at 662 keV was measured without any correction at -2400 V bias. Holes generated at all depths can be collected by the cathode at -2400 V bias which made depth correction using the cathode-to-anode ratio technique difficult since both charge carriers contribute to the signal. An energy resolution of 5.1% FWHM at 662 keV was obtained from the best pixel electrode without depth correction at +1000 V bias. In this positive bias case, the pixel electrode was actually collecting holes. A hole mobility-lifetime of 0.95×10-4 cm2/V has been estimated from measurement data.

Intelligent error correction method applied on an active pixel sensor based star tracker

NASA Astrophysics Data System (ADS)

Schmidt, Uwe

2005-10-01

Star trackers are opto-electronic sensors used on-board of satellites for the autonomous inertial attitude determination. During the last years star trackers became more and more important in the field of the attitude and orbit control system (AOCS) sensors. High performance star trackers are based up today on charge coupled device (CCD) optical camera heads. The active pixel sensor (APS) technology, introduced in the early 90-ties, allows now the beneficial replacement of CCD detectors by APS detectors with respect to performance, reliability, power, mass and cost. The company's heritage in star tracker design started in the early 80-ties with the launch of the worldwide first fully autonomous star tracker system ASTRO1 to the Russian MIR space station. Jena-Optronik recently developed an active pixel sensor based autonomous star tracker "ASTRO APS" as successor of the CCD based star tracker product series ASTRO1, ASTRO5, ASTRO10 and ASTRO15. Key features of the APS detector technology are, a true xy-address random access, the multiple windowing read out and the on-chip signal processing including the analogue to digital conversion. These features can be used for robust star tracking at high slew rates and under worse conditions like stray light and solar flare induced single event upsets. A special algorithm have been developed to manage the typical APS detector error contributors like fixed pattern noise (FPN), dark signal non-uniformity (DSNU) and white spots. The algorithm works fully autonomous and adapts to e.g. increasing DSNU and up-coming white spots automatically without ground maintenance or re-calibration. In contrast to conventional correction methods the described algorithm does not need calibration data memory like full image sized calibration data sets. The application of the presented algorithm managing the typical APS detector error contributors is a key element for the design of star trackers for long term satellite applications like geostationary telecom platforms.

Overview of the ATLAS Insertable B-Layer (IBL) Project

NASA Astrophysics Data System (ADS)

Kagan, M. A.

2014-06-01

The first upgrade for the Pixel Detector will be a new pixel layer which is currently under construction and will be installed during the first shutdown of the LHC machine, in 2013-14. The new detector, called the Insertable B-layer (IBL), will be installed between the existing Pixel Detector and a new, smaller radius beam-pipe. Two different silicon sensor technologies, planar n-in-n and 3D, will be used, connected with the new generation 130nm IBM CMOS FE-I4 readout chip via solder bump-bonds. A production quality control test bench was set up in the ATLAS inner detector assembly clean room to verify and rate the performance of the detector elements before integration around the beam-pipe. An overview of the IBL project, of the module design, the qualification for these sensor technologies, the integration quality control setups and recent results in the construction of this full scale new concept detector is discussed.

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

DOE PAGES

Zhang, Qingteng; Dufresne, Eric M.; Grybos, Pawel; ...

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. Lastly, the potential of extending the time resolution of XPCS beyond the limit set by the detector frame rate using dual counters is also discussed.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Qingteng; Dufresne, Eric M.; Grybos, Pawel

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. Lastly, the potential of extending the time resolution of XPCS beyond the limit set by the detector frame rate using dual counters is also discussed.

Commissioning of the ATLAS pixel detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

ATLAS Collaboration; Golling, Tobias

2008-09-01

The ATLAS pixel detector is a high precision silicon tracking device located closest to the LHC interaction point. It belongs to the first generation of its kind in a hadron collider experiment. It will provide crucial pattern recognition information and will largely determine the ability of ATLAS to precisely track particle trajectories and find secondary vertices. It was the last detector to be installed in ATLAS in June 2007, has been fully connected and tested in-situ during spring and summer 2008, and is ready for the imminent LHC turn-on. The highlights of the past and future commissioning activities of themore » ATLAS pixel system are presented.« less

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

PubMed

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.

Direct imaging detectors for electron microscopy

NASA Astrophysics Data System (ADS)

Faruqi, A. R.; McMullan, G.

2018-01-01

Electronic detectors used for imaging in electron microscopy are reviewed in this paper. Much of the detector technology is based on the developments in microelectronics, which have allowed the design of direct detectors with fine pixels, fast readout and which are sufficiently radiation hard for practical use. Detectors included in this review are hybrid pixel detectors, monolithic active pixel sensors based on CMOS technology and pnCCDs, which share one important feature: they are all direct imaging detectors, relying on directly converting energy in a semiconductor. Traditional methods of recording images in the electron microscope such as film and CCDs, are mentioned briefly along with a more detailed description of direct electronic detectors. Many applications benefit from the use of direct electron detectors and a few examples are mentioned in the text. In recent years one of the most dramatic advances in structural biology has been in the deployment of the new backthinned CMOS direct detectors to attain near-atomic resolution molecular structures with electron cryo-microscopy (cryo-EM). The development of direct detectors, along with a number of other parallel advances, has seen a very significant amount of new information being recorded in the images, which was not previously possible-and this forms the main emphasis of the review.

The LHCb VELO upgrade

NASA Astrophysics Data System (ADS)

Dosil Suárez, Álvaro; LHCb VELO Upgrade Group

2016-07-01

The upgrade of the LHCb experiment, planned for 2019, will transform the experiment to a trigger-less system reading out the full detector at 40 MHz event rate. All data reduction algorithms will be executed in a high-level software farm. The upgraded detector will run at luminosities of 2×1033 cm-2 s-1 and probe physics beyond the Standard Model in the heavy flavour sector with unprecedented precision. The Vertex Locator (VELO) is the silicon vertex detector surrounding the interaction region. The current detector will be replaced with a hybrid pixel system equipped with electronics capable of reading out at 40 MHz. The detector comprises silicon pixel sensors with 55×55 μm2 pitch, read out by the VeloPix ASIC, based on the TimePix/MediPix family. The hottest region will have pixel hit rates of 900 Mhits/s yielding a total data rate more than 3 Tbit/s for the upgraded VELO. The detector modules are located in a separate vacuum, separated from the beam vacuum by a thin custom made foil. The detector halves are retracted when the beams are injected and closed at stable beams, positioning the first sensitive pixel at 5.1 mm from the beams. The material budget will be minimised by the use of evaporative CO2 coolant circulating in microchannels within 400 μm thick silicon substrates.

Performance overview of the Euclid infrared focal plane detector subsystems

NASA Astrophysics Data System (ADS)

Waczynski, A.; Barbier, R.; Cagiano, S.; Chen, J.; Cheung, S.; Cho, H.; Cillis, A.; Clémens, J.-C.; Dawson, O.; Delo, G.; Farris, M.; Feizi, A.; Foltz, R.; Hickey, M.; Holmes, W.; Hwang, T.; Israelsson, U.; Jhabvala, M.; Kahle, D.; Kan, Em.; Kan, Er.; Loose, M.; Lotkin, G.; Miko, L.; Nguyen, L.; Piquette, E.; Powers, T.; Pravdo, S.; Runkle, A.; Seiffert, M.; Strada, P.; Tucker, C.; Turck, K.; Wang, F.; Weber, C.; Williams, J.

2016-07-01

In support of the European space agency (ESA) Euclid mission, NASA is responsible for the evaluation of the H2RG mercury cadmium telluride (MCT) detectors and electronics assemblies fabricated by Teledyne imaging systems. The detector evaluation is performed in the detector characterization laboratory (DCL) at the NASA Goddard space flight center (GSFC) in close collaboration with engineers and scientists from the jet propulsion laboratory (JPL) and the Euclid project. The Euclid near infrared spectrometer and imaging photometer (NISP) will perform large area optical and spectroscopic sky surveys in the 0.9-2.02 μm infrared (IR) region. The NISP instrument will contain sixteen detector arrays each coupled to a Teledyne SIDECAR application specific integrated circuit (ASIC). The focal plane will operate at 100K and the SIDECAR ASIC will be in close proximity operating at a slightly higher temperature of 137K. This paper will describe the test configuration, performance tests and results of the latest engineering run, also known as pilot run 3 (PR3), consisting of four H2RG detectors operating simultaneously. Performance data will be presented on; noise, spectral quantum efficiency, dark current, persistence, pixel yield, pixel to pixel uniformity, linearity, inter pixel crosstalk, full well and dynamic range, power dissipation, thermal response and unit cell input sensitivity.

Three-Dimensional Super-Resolution: Theory, Modeling, and Field Tests Results

NASA Technical Reports Server (NTRS)

Bulyshev, Alexander; Amzajerdian, Farzin; Roback, Vincent E.; Hines, Glenn; Pierrottet, Diego; Reisse, Robert

2014-01-01

Many flash lidar applications continue to demand higher three-dimensional image resolution beyond the current state-of-the-art technology of the detector arrays and their associated readout circuits. Even with the available number of focal plane pixels, the required number of photons for illuminating all the pixels may impose impractical requirements on the laser pulse energy or the receiver aperture size. Therefore, image resolution enhancement by means of a super-resolution algorithm in near real time presents a very attractive solution for a wide range of flash lidar applications. This paper describes a superresolution technique and illustrates its performance and merits for generating three-dimensional image frames at a video rate.

Limit characteristics of digital optoelectronic processor

NASA Astrophysics Data System (ADS)

Kolobrodov, V. G.; Tymchik, G. S.; Kolobrodov, M. S.

2018-01-01

In this article, the limiting characteristics of a digital optoelectronic processor are explored. The limits are defined by diffraction effects and a matrix structure of the devices for input and output of optical signals. The purpose of a present research is to optimize the parameters of the processor's components. The developed physical and mathematical model of DOEP allowed to establish the limit characteristics of the processor, restricted by diffraction effects and an array structure of the equipment for input and output of optical signals, as well as to optimize the parameters of the processor's components. The diameter of the entrance pupil of the Fourier lens is determined by the size of SLM and the pixel size of the modulator. To determine the spectral resolution, it is offered to use a concept of an optimum phase when the resolved diffraction maxima coincide with the pixel centers of the radiation detector.

Conception and characterization of a virtual coplanar grid for a 11×11 pixelated CZT detector

NASA Astrophysics Data System (ADS)

Espagnet, Romain; Frezza, Andrea; Martin, Jean-Pierre; Hamel, Louis-André; Després, Philippe

2017-07-01

Due to the low mobility of holes in CZT, commercially available detectors with a relatively large volume typically use a pixelated anode structure. They are mostly used in imaging applications and often require a dense electronic readout scheme. These large volume detectors are also interesting for high-sensitivity applications and a CZT-based blood gamma counter was developed from a 20×20×15 mm3 crystal available commercially and having a 11×11 pixelated readout scheme. A method is proposed here to reduce the number of channels required to use the crystal in a high-sensitivity counting application, dedicated to pharmacokinetic modelling in PET and SPECT. Inspired by a classic coplanar anode, an implementation of a virtual coplanar grid was done by connecting the 121 pixels of the detector to form intercalated bands. The layout, the front-end electronics and the characterization of the detector in this 2-channel anode geometry is presented. The coefficients required to compensate for electron trapping in CZT were determined experimentally to improve the performance. The resulting virtual coplanar detector has an intrinsic efficiency of 34% and an energy resolution of 8% at 662 keV. The detector's response was linear between 80 keV and 1372 keV. This suggests that large CZT crystals offer an excellent alternative to scintillation detectors for some applications, especially those where high-sensitivity and compactness are required.

Photon Counting Energy Dispersive Detector Arrays for X-ray Imaging

PubMed Central

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/mm2/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 57Co source. An output rate of 6×106 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 energy-dispersive detector modules, are shown. PMID:19920884

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

PubMed

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 energy-dispersive detector modules, are shown.

Development of a DC-DC conversion powering scheme for the CMS Phase-1 pixel upgrade

NASA Astrophysics Data System (ADS)

Feld, L.; Fimmers, C.; Karpinski, W.; Klein, K.; Lipinski, M.; Preuten, M.; Rauch, M.; Rittich, D.; Sammet, J.; Wlochal, M.

2014-01-01

A novel powering scheme based on the DC-DC conversion technique will be exploited to power the CMS Phase-1 pixel detector. DC-DC buck converters for the CMS pixel project have been developed, based on the AMIS5 ASIC designed by CERN. The powering system of the Phase-1 pixel detector is described and the performance of the converter prototypes is detailed, including power efficiency, stability of the output voltage, shielding, and thermal management. Results from a test of the magnetic field tolerance of the DC-DC converters are reported. System tests with pixel modules using many components of the future pixel barrel system are summarized. Finally first impressions from a pre-series of 200 DC-DC converters are presented.

Advanced uncooled sensor product development

NASA Astrophysics Data System (ADS)

Kennedy, A.; Masini, P.; Lamb, M.; Hamers, J.; Kocian, T.; Gordon, E.; Parrish, W.; Williams, R.; LeBeau, T.

2015-06-01

The partnership between RVS, Seek Thermal and Freescale Semiconductor continues on the path to bring the latest technology and innovation to both military and commercial customers. The partnership has matured the 17μm pixel for volume production on the Thermal Weapon Sight (TWS) program in efforts to bring advanced production capability to produce a low cost, high performance product. The partnership has developed the 12μm pixel and has demonstrated performance across a family of detector sizes ranging from formats as small as 206 x 156 to full high definition formats. Detector pixel sensitivities have been achieved using the RVS double level advanced pixel structure. Transition of the packaging of microbolometers from a traditional die level package to a wafer level package (WLP) in a high volume commercial environment is complete. Innovations in wafer fabrication techniques have been incorporated into this product line to assist in the high yield required for volume production. The WLP seal yield is currently > 95%. Simulated package vacuum lives >> 20 years have been demonstrated through accelerated life testing where the package has been shown to have no degradation after 2,500 hours at 150°C. Additionally the rugged assembly has shown no degradation after mechanical shock and vibration and thermal shock testing. The transition to production effort was successfully completed in 2014 and the WLP design has been integrated into multiple new production products including the TWS and the innovative Seek Thermal commercial product that interfaces directly to an iPhone or android device.

Pixelated filters for spatial imaging

NASA Astrophysics Data System (ADS)

Mathieu, Karine; Lequime, Michel; Lumeau, Julien; Abel-Tiberini, Laetitia; Savin De Larclause, Isabelle; Berthon, Jacques

2015-10-01

Small satellites are often used by spatial agencies to meet scientific spatial mission requirements. Their payloads are composed of various instruments collecting an increasing amount of data, as well as respecting the growing constraints relative to volume and mass; So small-sized integrated camera have taken a favored place among these instruments. To ensure scene specific color information sensing, pixelated filters seem to be more attractive than filter wheels. The work presented here, in collaboration with Institut Fresnel, deals with the manufacturing of this kind of component, based on thin film technologies and photolithography processes. CCD detectors with a pixel pitch about 30 μm were considered. In the configuration where the matrix filters are positioned the closest to the detector, the matrix filters are composed of 2x2 macro pixels (e.g. 4 filters). These 4 filters have a bandwidth about 40 nm and are respectively centered at 550, 700, 770 and 840 nm with a specific rejection rate defined on the visible spectral range [500 - 900 nm]. After an intense design step, 4 thin-film structures have been elaborated with a maximum thickness of 5 μm. A run of tests has allowed us to choose the optimal micro-structuration parameters. The 100x100 matrix filters prototypes have been successfully manufactured with lift-off and ion assisted deposition processes. High spatial and spectral characterization, with a dedicated metrology bench, showed that initial specifications and simulations were globally met. These excellent performances knock down the technological barriers for high-end integrated specific multi spectral imaging.

Modelling and testing the x-ray performance of CCD and CMOS APS detectors using numerical finite element simulations

NASA Astrophysics Data System (ADS)

Weatherill, Daniel P.; Stefanov, Konstantin D.; Greig, Thomas A.; Holland, Andrew D.

2014-07-01

Pixellated monolithic silicon detectors operated in a photon-counting regime are useful in spectroscopic imaging applications. Since a high energy incident photon may produce many excess free carriers upon absorption, both energy and spatial information can be recovered by resolving each interaction event. The performance of these devices in terms of both the energy and spatial resolution is in large part determined by the amount of diffusion which occurs during the collection of the charge cloud by the pixels. Past efforts to predict the X-ray performance of imaging sensors have used either analytical solutions to the diffusion equation or simplified monte carlo electron transport models. These methods are computationally attractive and highly useful but may be complemented using more physically detailed models based on TCAD simulations of the devices. Here we present initial results from a model which employs a full transient numerical solution of the classical semiconductor equations to model charge collection in device pixels under stimulation from initially Gaussian photogenerated charge clouds, using commercial TCAD software. Realistic device geometries and doping are included. By mapping the pixel response to different initial interaction positions and charge cloud sizes, the charge splitting behaviour of the model sensor under various illuminations and operating conditions is investigated. Experimental validation of the model is presented from an e2v CCD30-11 device under varying substrate bias, illuminated using an Fe-55 source.

Performance simulation of an x-ray detector for spectral CT with combined Si and Cd[Zn]Te detection layers.

PubMed

Herrmann, Christoph; Engel, Klaus-Jürgen; Wiegert, Jens

2010-12-21

The most obvious problem in obtaining spectral information with energy-resolving photon counting detectors in clinical computed tomography (CT) is the huge x-ray flux present in conventional CT systems. At high tube voltages (e.g. 140 kVp), despite the beam shaper, this flux can be close to 10⁹ Mcps mm⁻² in the direct beam or in regions behind the object, which are close to the direct beam. Without accepting the drawbacks of truncated reconstruction, i.e. estimating missing direct-beam projection data, a photon-counting energy-resolving detector has to be able to deal with such high count rates. Sub-structuring pixels into sub-pixels is not enough to reduce the count rate per pixel to values that today's direct converting Cd[Zn]Te material can cope with (≤ 10 Mcps in an optimistic view). Below 300 µm pixel pitch, x-ray cross-talk (Compton scatter and K-escape) and the effect of charge diffusion between pixels are problematic. By organising the detector in several different layers, the count rate can be further reduced. However this alone does not limit the count rates to the required level, since the high stopping power of the material becomes a disadvantage in the layered approach: a simple absorption calculation for 300 µm pixel pitch shows that the required layer thickness of below 10 Mcps/pixel for the top layers in the direct beam is significantly below 100 µm. In a horizontal multi-layer detector, such thin layers are very difficult to manufacture due to the brittleness of Cd[Zn]Te. In a vertical configuration (also called edge-on illumination (Ludqvist et al 2001 IEEE Trans. Nucl. Sci. 48 1530-6, Roessl et al 2008 IEEE NSS-MIC-RTSD 2008, Conf. Rec. Talk NM2-3)), bonding of the readout electronics (with pixel pitches below 100 µm) is not straightforward although it has already been done successfully (Pellegrini et al 2004 IEEE NSS MIC 2004 pp 2104-9). Obviously, for the top detector layers, materials with lower stopping power would be advantageous. The possible choices are, however, quite limited, since only 'mature' materials, which operate at room temperature and can be manufactured reliably should reasonably be considered. Since GaAs is still known to cause reliability problems, the simplest choice is Si, however with the drawback of strong Compton scatter which can cause considerable inter-pixel cross-talk. To investigate the potential and the problems of Si in a multi-layer detector, in this paper the combination of top detector layers made of Si with lower layers made of Cd[Zn]Te is studied by using Monte Carlo simulated detector responses. It is found that the inter-pixel cross-talk due to Compton scatter is indeed very high; however, with an appropriate cross-talk correction scheme, which is also described, the negative effects of cross-talk are shown to be removed to a very large extent.

A 2D silicon detector array for quality assurance in small field dosimetry: DUO.

PubMed

Shukaili, Khalsa Al; Petasecca, Marco; Newall, Matthew; Espinoza, Anthony; Perevertaylo, Vladimir L; Corde, Stéphanie; Lerch, Michael; Rosenfeld, Anatoly B

2017-02-01

Nowadays, there are many different applications that use small fields in radiotherapy treatments. The dosimetry of small radiation fields is not trivial due to the problems associated with lateral disequilibrium and source occlusion and requires reliable quality assurance (QA). Ideally such a QA tool should provide high spatial resolution, minimal beam perturbation and real time fast measurements. Many different types of silicon diode arrays are used for QA in radiotherapy; however, their application in small filed dosimetry is limited, in part, due to a lack of spatial resolution. The Center of Medical Radiation Physics (CMRP) has developed a new generation of a monolithic silicon diode array detector that will be useful for small field dosimetry in SRS/SRT. The objective of this study is to characterize a monolithic silicon diode array designed for dosimetry QA in SRS/SRT named DUO that is arranged as two orthogonal 1D arrays with 0.2 mm pitch. DUO is two orthogonal 1D silicon detector arrays in a monolithic crystal. Each orthogonal array contains 253 small pixels with size 0.04 × 0.8 mm 2 and three central pixels are with a size of 0.18 × 0.18 mm 2 each. The detector pitch is 0.2 mm and total active area is 52 × 52 mm 2 . The response of the DUO silicon detector was characterized in terms of dose per pulse, percentage depth dose, and spatial resolution in a radiation field incorporating high gradients. Beam profile of small fields and output factors measured on a Varian 2100EX LINAC in a 6 MV radiation fields of square dimensions and sized from 0.5 × 0.5 cm 2 to 5 × 5 cm 2 . The DUO response was compared under the same conditions with EBT3 films and an ionization chamber. The DUO detector shows a dose per pulse dependence of 5% for a range of dose rates from 2.7 × 10 -4 to 1.2 × 10 -4 Gy/pulse and 23% when the rate is further reduced to 2.8 × 10 -5 Gy/pulse. The percentage depth dose measured to 25 cm depth in solid water phantom beyond the surface and for a field size of 10 × 10 cm 2 agrees with that measured using a Markus IC within 1.5%. The beam profiles in both X and Y orthogonal directions showed a good match with EBT3 film, where the FWHM agreed within 1% and penumbra widths within 0.5 mm. The effect of an air gap above the DUO detector has also been studied. The output factor for field sizes ranging from 0.5 × 0.5 cm 2 to 5 × 5 cm 2 measured by the DUO detector with a 0.5 mm air gap above silicon surface agrees with EBT3 film and MOSkin detectors within 1.8%. The CMRP's monolithic silicon detector array, DUO, is suitable for SRS/SRT dosimetry and QA because of its very high spatial resolution (0.2 mm) and real time operation. © 2016 American Association of Physicists in Medicine.

Application of pixel-cell detector technology for Advanced Neutron Beam Monitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kopp, Daniel M.

2011-01-11

Application of Pixel-Cell Detector Technology for Advanced Neutron Beam Monitors Specifications of currently available neutron beam detectors limit their usefulness at intense neutron beams of large-scale national user facilities used for the advanced study of materials. A large number of neutron-scattering experiments require beam monitors to operate in an intense neutron beam flux of >10E+7 neutrons per second per square centimeter. For instance, a 4 cm x 4 cm intense beam flux of 6.25 x 10E+7 n/s/cm2 at the Spallation Neutron Source will put a flux of 1.00 x 10E+9 n/s at the beam monitor. Currently available beam monitors withmore » a typical efficiency of 1 x 10E-4 will need to be replaced in less than two years of operation due to wire and gas degradation issues. There is also a need at some instruments for beam position information that are beyond the capabilities of currently available He-3 and BF3 neutron beam monitors. ORDELA, Inc.’s research under USDOE SBIR Grant (DE-FG02-07ER84844) studied the feasibility of using pixel-cell technology for developing a new generation of stable, long-life neutron beam monitors. The research effort has led to the development and commercialization of advanced neutron beam detectors that will directly benefit the Spallation Neutron Source and other intense neutron sources such as the High Flux Isotope Reactor. A prototypical Pixel-Cell Neutron Beam Monitor was designed and constructed during this research effort. This prototype beam monitor was exposed to an intense neutron beam at the HFIR SNS HB-2 test beam site. Initial measurements on efficiency, uniformity across the detector, and position resolution yielded excellent results. The development and test results have provided the required data to initiate the fabrication and commercialization of this next generation of neutron-detector systems. ORDELA, Inc. has (1) identified low-cost design and fabrication strategies, (2) developed and built pixel-cell detectors and instrumented a 64-pixel-cell detector to specifications for the Cold-Neutron Chopper Spectrometer and POWGEN instruments, (3) investigated the general characteristics of this technology, (4) studied pixel-cell configurations and arrived at an optimized modular design, and (5) evaluated fabrication costs of mass production for these configurations. The resulting technology will enable a complete line of pixel-cell-based neutron detectors to be commercially under available. ORDELA, Inc has a good track history of application of innovative technology into the marketplace. Our commercialization record reflects this. For additional information, please contact Daniel Kopp at ORDELA, Inc. at +1 (865) 483-8675 or check our website at www.ordela.com.« less

75 FR 82372 - Application(s) for Duty-Free Entry of Scientific Instruments

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-30

..., Argonne LLC, 9700 South Cass Ave., Lemont, IL 60439. Instrument: Pilatus 100K Pixel Detector System... efficiency (no readout noise and direct detection scheme), high dynamic range (20-bits), and fast readout.... Instrument: Pilatus 300K Pixel Detector System. Manufacturer: Dectris Ltd., Switzerland. Intended Use: The...

MIXS on BepiColombo and its DEPFET based focal plane instrumentation

NASA Astrophysics Data System (ADS)

Treis, J.; Andricek, L.; Aschauer, F.; Heinzinger, K.; Herrmann, S.; Hilchenbach, M.; Lauf, T.; Lechner, P.; Lutz, G.; Majewski, P.; Porro, M.; Richter, R. H.; Schaller, G.; Schnecke, M.; Schopper, F.; Soltau, H.; Stefanescu, A.; Strüder, L.; de Vita, G.

2010-12-01

Focal plane instrumentation based on DEPFET Macropixel devices, being a combination of the Detector-Amplifier structure DEPFET with a silicon drift chamber (SDD), has been proposed for the MIXS (Mercury Imaging X-ray Spectrometer) instrument on ESA's Mercury exploration mission BepiColombo. MIXS images X-ray fluorescent radiation from the Mercury surface with a lightweight X-ray mirror system on the focal plane detector to measure the spatially resolved element abundance in Mercury's crust. The sensor needs to have an energy resolution better than 200 eV FWHM at 1 keV and is required to cover an energy range from 0.5 to 10 keV, for a pixel size of 300×300μm2. Main challenges for the instrument are radiation damage and the difficult thermal environment in the mercury orbit. The production of the first batch of flight devices has been finished at the MPI semiconductor laboratory. Prototype modules have been assembled to verify the electrical properties of the devices; selected results are presented here. The prototype devices, Macropixel prototypes for the SIMBOL-X focal plane, are electrically fully compatible, but have a pixel size of 0.5×0.5 mm2. Excellent homogeneity and near Fano-limited energy resolution at high readout speeds have been observed on these devices.

Spatio-energetic cross-talk in photon counting detectors: Numerical detector model (PcTK) and workflow for CT image quality assessment.

PubMed

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

2018-05-01

The interpixel cross-talk of energy-sensitive photon counting x-ray detectors (PCDs) has been studied and an analytical model (version 2.1) has been developed for double-counting between neighboring pixels due to charge sharing and K-shell fluorescence x-ray emission followed by its reabsorption (Taguchi K, et al., Medical Physics 2016;43(12):6386-6404). While the model version 2.1 simulated the spectral degradation well, it had the following problems that has been found to be significant recently: (1) The spectrum is inaccurate with smaller pixel sizes; (2) the charge cloud size must be smaller than the pixel size; (3) the model underestimates the spectrum/counts for 10-40 keV; and (4) the model version 2.1 cannot handlen-tuple-counting withn > 2 (i.e., triple-counting or higher). These problems are inherent to the design of the model version 2.1; therefore, we developed a new model and addressed these problems in this study. We propose a new PCD cross-talk model (version 3.2; Pc TK for "photon counting toolkit") that is based on a completely different design concept from the previous version. It uses a numerical approach and starts with a 2-D model of charge sharing (as opposed to an analytical approach and a 1-D model with version 2.1) and addresses all of the four problems. The model takes the following factors into account: (1) shift-variant electron density of the charge cloud (Gaussian-distributed), (2) detection efficiency, (3) interactions between photons and PCDs via photoelectric effect, and (4) electronic noise. Correlated noisy PCD data can be generated using either a multivariate normal random number generator or a Poisson random number generator. The effect of the two parameters, the effective charge cloud diameter (d 0 ) and pixel size (d pix ), was studied and results were compared with Monte Carlo simulations and the previous model version 2.1. Finally, a script for the workflow for CT image quality assessment has been developed, which started with a few material density images, generated material-specific sinogram (line integrals) data, noisy PCD data with spectral distortion using the model version 3.2, and reconstructed PCD- CT images for four energy windows. The model version 3.2 addressed all of the four problems listed above. The spectra withd pix  = 56-113 μm agreed with that of Medipix3 detector withd pix  = 55-110 μm without charge summing mode qualitatively. The counts for 10-40 keV were larger than the previous model (version 2.1) and agreed with MC simulations very well (root-mean-square difference values with model version 3.2 were decreased to 16%-67% of the values with version 2.1). There were many non-zero off-diagonal elements withn-tuple-counting withn > 2 in the normalized covariance matrix of 3 × 3 neighboring pixels. Reconstructed images showed biases and artifacts attributed to the spectral distortion due to the charge sharing and fluorescence x rays. We have developed a new PCD model for spatio-energetic cross-talk and correlation between PCD pixels. The workflow demonstrated the utility of the model for general or task-specific image quality assessments for the PCD- CT.Note: The program (Pc TK) and the workflow scripts have been made available to academic researchers. Interested readers should visit the website (pctk.jhu.edu) or contact the corresponding author. © 2018 American Association of Physicists in Medicine.

Optical modeling of waveguide coupled TES detectors towards the SAFARI instrument for SPICA

NASA Astrophysics Data System (ADS)

Trappe, N.; Bracken, C.; Doherty, S.; Gao, J. R.; Glowacka, D.; Goldie, D.; Griffin, D.; Hijmering, R.; Jackson, B.; Khosropanah, P.; Mauskopf, P.; Morozov, D.; Murphy, A.; O'Sullivan, C.; Ridder, M.; Withington, S.

2012-09-01

The next generation of space missions targeting far-infrared wavelengths will require large-format arrays of extremely sensitive detectors. The development of Transition Edge Sensor (TES) array technology is being developed for future Far-Infrared (FIR) space applications such as the SAFARI instrument for SPICA where low-noise and high sensitivity is required to achieve ambitious science goals. In this paper we describe a modal analysis of multi-moded horn antennas feeding integrating cavities housing TES detectors with superconducting film absorbers. In high sensitivity TES detector technology the ability to control the electromagnetic and thermo-mechanical environment of the detector is critical. Simulating and understanding optical behaviour of such detectors at far IR wavelengths is difficult and requires development of existing analysis tools. The proposed modal approach offers a computationally efficient technique to describe the partial coherent response of the full pixel in terms of optical efficiency and power leakage between pixels. Initial wok carried out as part of an ESA technical research project on optical analysis is described and a prototype SAFARI pixel design is analyzed where the optical coupling between the incoming field and the pixel containing horn, cavity with an air gap, and thin absorber layer are all included in the model to allow a comprehensive optical characterization. The modal approach described is based on the mode matching technique where the horn and cavity are described in the traditional way while a technique to include the absorber was developed. Radiation leakage between pixels is also included making this a powerful analysis tool.

Study of prototypes of LFoundry active CMOS pixels sensors for the ATLAS detector

NASA Astrophysics Data System (ADS)

Vigani, L.; Bortoletto, D.; Ambroz, L.; Plackett, R.; Hemperek, T.; Rymaszewski, P.; Wang, T.; Krueger, H.; Hirono, T.; Caicedo Sierra, I.; Wermes, N.; Barbero, M.; Bhat, S.; Breugnon, P.; Chen, Z.; Godiot, S.; Pangaud, P.; Rozanov, A.

2018-02-01

Current high energy particle physics experiments at the LHC use hybrid silicon detectors, in both pixel and strip configurations, for their inner trackers. These detectors have proven to be very reliable and performant. Nevertheless, there is great interest in depleted CMOS silicon detectors, which could achieve a similar performance at lower cost of production. We present recent developments of this technology in the framework of the ATLAS CMOS demonstrator project. In particular, studies of two active sensors from LFoundry, CCPD_LF and LFCPIX, are shown.

Optical sectioning in wide-field microscopy obtained by dynamic structured light illumination and detection based on a smart pixel detector array.

PubMed

Mitić, Jelena; Anhut, Tiemo; Meier, Matthias; Ducros, Mathieu; Serov, Alexander; Lasser, Theo

2003-05-01

Optical sectioning in wide-field microscopy is achieved by illumination of the object with a continuously moving single-spatial-frequency pattern and detecting the image with a smart pixel detector array. This detector performs an on-chip electronic signal processing that extracts the optically sectioned image. The optically sectioned image is directly observed in real time without any additional postprocessing.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, H; Ding, H; Molloi, S

Purpose: To investigate the feasibility of micro-calcification (μCa) detectability by using an energy-resolved photon-counting Si strip detector for spectral breast computed tomography (CT). Methods: A bench-top CT system was constructed using a tungsten anode x-ray source with a focal spot size of 0.8 mm and a single line 256-pixel Si strip photon counting detector with a pixel pitch of 100 μm. The slice thickness was 0.5 mm. Five different size groups of calcium carbonate grains, from 105 to 215 μm in diameter, were embedded in a cylindrical resin phantom with a diameter of 16 mm to simulate μCas. The phantomsmore » were imaged at 65 kVp with an Entrance Skin Air Kerma (ESAK) of 1.2, 3, 6, and 8 mGy. The images were reconstructed using a standard filtered back projection (FBP) with a ramp filter. A total of 200 μCa images (5 different sizes of μCas × 4 different doses × 10 images for each setting) were combined with another 200 control images without μCas, to ultimately form 400 images for the reader study. The images were displayed in random order to three blinded observers, who were asked to give a binary score on each image regarding the presence of μCas. The μCa detectability for each image was evaluated in terms of binary decision theory metrics. The sensitivity, specificity, and accuracy were calculated to study the size and dose-dependence for μCa detectability. Additionally, the influence of the partial volume effect on the μCa detectability was investigated by simulation. Results: For a μCa larger than 140 μm in diameter, detection accuracy of above 90 % was achieved with the investigated prototype spectral CT system at ESAK of 1.2 mGy. Conclusion: The proposed Si strip detector is expected to offer superior image quality with the capability to detect μCas for low dose breast imaging.« less

Development of an ultra-high temperature infrared scene projector at Santa Barbara Infrared Inc.

NASA Astrophysics Data System (ADS)

Franks, Greg; Laveigne, Joe; Danielson, Tom; McHugh, Steve; Lannon, John; Goodwin, Scott

2015-05-01

The rapid development of very-large format infrared detector arrays has challenged the IR scene projector community to develop correspondingly larger-format infrared emitter arrays to support the testing needs of systems incorporating these detectors. As with most integrated circuits, fabrication yields for the read-in integrated circuit (RIIC) that drives the emitter pixel array are expected to drop dramatically with increasing size, making monolithic RIICs larger than the current 1024x1024 format impractical and unaffordable. Additionally, many scene projector users require much higher simulated temperatures than current technology can generate to fully evaluate the performance of their systems and associated processing algorithms. Under the Ultra High Temperature (UHT) development program, Santa Barbara Infrared Inc. (SBIR) is developing a new infrared scene projector architecture capable of producing both very large format (>1024x1024) resistive emitter arrays and improved emitter pixel technology capable of simulating very high apparent temperatures. During an earlier phase of the program, SBIR demonstrated materials with MWIR apparent temperatures in excess of 1000K. New emitter materials have subsequently been selected to produce pixels that achieve even higher apparent temperatures. Test results from pixels fabricated using the new material set will be presented and discussed. Also in development under the same UHT program is a 'scalable' RIIC that will be used to drive the high temperature pixels. This RIIC will utilize through-silicon vias (TSVs) and quilt packaging (QP) technologies to allow seamless tiling of multiple chips to fabricate very large arrays, and thus overcome the inherent yield limitations of very-large-scale integrated circuits. Current status of the RIIC development effort will also be presented.

Pixel detectors for use in retina neurophysiology studies

NASA Astrophysics Data System (ADS)

Cunningham, W.; Mathieson, K.; Horn, M.; Melone, J.; McEwan, F. A.; Blue, A.; O'Shea, V.; Smith, K. M.; Litke, A.; Chichilnisky, E. J.; Rahman, M.

2003-08-01

One area of major inter-disciplinary co-operation is between the particle physics and bio-medical communities. The type of large detector arrays and fast electronics developed in laboratories like CERN are becoming used for a wide range of medical and biological experiments. In the present work fabrication technology developed for producing semiconductor radiation detectors has been applied to produce arrays which have been used in neuro-physiological experiments on retinal tissue. We have exploited UVIII, a low molecular weight resist, that has permitted large area electron beam lithography. This allows the resolution to go below that of conventional photolithography and hence the production of densely packed ˜500 electrode arrays with feature sizes down to below 2 μm. The neural signals from significant areas of the retina may thus be captured.

Periodicity analysis on cat-eye reflected beam profiles of optical detectors

NASA Astrophysics Data System (ADS)

Gong, Mali; He, Sifeng

2017-05-01

The cat-eye effect reflected beam profiles of most optical detectors have a certain characteristic of periodicity, which is caused by array arrangement of sensors at their optical focal planes. It is the first time to find and prove that the reflected beam profile becomes several periodic spots at the reflected propagation distance corresponding to half the imaging distance of a CCD camera. Furthermore, the spatial cycle of these spots is approximately constant, independent of the CCD camera's imaging distance, which is related only to the focal length and pixel size of the CCD sensor. Thus, we can obtain the imaging distance and intrinsic parameters of the optical detector by analyzing its cat-eye reflected beam profiles. This conclusion can be applied in the field of non-cooperative cat-eye target recognition.

Simple alignment procedure for a VNIR imaging spectrometer with a Shack-Hartmann wavefront sensor and a field identifier

NASA Astrophysics Data System (ADS)

Lee, Jun Ho; Hwang, Sunglyoung; Jeong, Dohwan; Hong, Jinsuk; Kim, Youngsoo; Kim, Yeonsoo; Kim, Hyunsook

2017-09-01

We report an innovative simple alignment method for a VNIR spectrometer in the wavelength region of 400-900 nm; this device is later combined with fore-optics (a telescope) to form a f/2.5 hyperspectral imaging spectrometer with a field of view of +/-7.68°. The detector at the final image plane is a 640×480 charge-coupled device with a 24 μm pixel size. We first assembled the fore-optics and the spectrometer separately and then combined them via a slit co-located on the image plane of the fore-optics and the object plane of the spectrometer. The spectrometer was assembled in three steps. In the initial step, the optics was simply assembled with an optical axis guiding He-Ne laser. In the second step, we located a pin-hole on the slit plane and a Shack-Hartmann sensor on the detector plane. The wavefront errors over the full field were scanned simply by moving the point source along the slit direction while the Shack-Hartmann sensor was constantly conjugated to the pin-hole position by a motorized stage. Optimal alignment was then performed based on the reverse sensitivity method. In the final stage, the pin-hole and the Shack-Hartmann sensor were exchanged with an equispaced 10 pin-hole slit called a field identifier and a detector. The light source was also changed from the laser (single wavelength source) to a krypton lamp (discrete multi-wavelength source). We were then easily able to calculate the distortion and keystone on the detector plane without any scanning or moving optical components; rather, we merely calculated the spectral centroids of the 10 pin-holes on the detector. We then tuned the clocking angles of the convex grating and the detector to minimize the distortion and keystone. The final assembly was tested and found to have an RMS WFE < 90 nm over the entire field of view, a keystone of 0.08 pixels, a smile of 1.13 pixels and a spectral resolution of 4.32 nm.

Feasibility of estimating volumetric breast density from mammographic x-ray spectra using a cadmium telluride photon-counting detector.

PubMed

Ghammraoui, Bahaa; Badal, Andreu; Glick, Stephen J

2018-06-03

Mammographic density of glandular breast tissue has a masking effect that can reduce lesion detection accuracy and is also a strong risk factor for breast cancer. Therefore, accurate quantitative estimation of breast density is clinically important. In this study, we investigate experimentally the feasibility of quantifying volumetric breast density with spectral mammography using a CdTe-based photon-counting detector. To demonstrate proof-of-principle, this study was carried out using the single pixel Amptek XR-100T-CdTe detector. The total number of x rays recorded by the detector from a single pencil-beam projection through 50%/50% of adipose/glandular mass fraction-equivalent phantoms was measured. Material decomposition assuming two, four, and eight energy bins was then applied to characterize the inspected phantom into adipose and glandular using log-likelihood estimation, taking into account the polychromatic source, the detector response function, and the energy-dependent attenuation. Measurement tests were carried out for different doses, kVp settings, and different breast sizes. For dose of 1 mGy and above, the percent relative root mean square (RMS) errors of the estimated breast density was measured below 7% for all three phantom studies. It was also observed that some decrease in RMS errors was achieved using eight energy bins. For 3 and 4 cm thick phantoms, performance at 40 and 45 kVp showed similar performance. However, it was observed that 45 kVp showed better performance for a phantom thickness of 6 cm at low dose levels due to increased statistical variation at lower photon count levels with 40 kVp. The results of the current study suggest that photon-counting spectral mammography systems using CdTe detectors have the potential to be used for accurate quantification of volumetric breast density on a pixel-to-pixel basis, with an RMS error of less than 7%. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Real-time continuous-wave terahertz line scanner based on a compact 1 × 240 InGaAs Schottky barrier diode array detector.

PubMed

Han, Sang-Pil; Ko, Hyunsung; Kim, Namje; Lee, Won-Hui; Moon, Kiwon; Lee, Il-Min; Lee, Eui Su; Lee, Dong Hun; Lee, Wangjoo; Han, Seong-Tae; Choi, Sung-Wook; Park, Kyung Hyun

2014-11-17

We demonstrate real-time continuous-wave terahertz (THz) line-scanned imaging based on a 1 × 240 InGaAs Schottky barrier diode (SBD) array detector with a scan velocity of 25 cm/s, a scan line length of 12 cm, and a pixel size of 0.5 × 0.5 mm². Foreign substances, such as a paper clip with a spatial resolution of approximately 1 mm that is hidden under a cracker, are clearly detected by this THz line-scanning system. The system consists of the SBD array detector, a 200-GHz gyrotron source, a conveyor system, and several optical components such as a high-density polyethylene cylindrical lens, metal cylindrical mirror, and THz wire-grid polarizer. Using the THz polarizer, the signal-to-noise ratio of the SBD array detector improves because the quality of the source beam is enhanced.

Tritium autoradiography with thinned and back-side illuminated monolithic active pixel sensor device

NASA Astrophysics Data System (ADS)

Deptuch, G.

2005-05-01

The first autoradiographic results of the tritium ( 3H) marked source obtained with monolithic active pixel sensors are presented. The detector is a high-resolution, back-side illuminated imager, developed within the SUCIMA collaboration for low-energy (<30 keV) electrons detection. The sensitivity to these energies is obtained by thinning the detector, originally fabricated in the form of a standard VLSI chip, down to the thickness of the epitaxial layer. The detector used is the 1×10 6 pixel, thinned MIMOSA V chip. The low noise performance and thin (˜160 nm) entrance window provide the sensitivity of the device to energies as low as ˜4 keV. A polymer tritium source was parked directly atop the detector in open-air conditions. A real-time image of the source was obtained.

Mosaic-Detector-Based Fluorescence Spectral Imager

NASA Technical Reports Server (NTRS)

Son, Kyung-Ah; Moon, Jeong

2007-01-01

A battery-powered, pen-sized, portable instrument for measuring molecular fluorescence spectra of chemical and biological samples in the field has been proposed. Molecular fluorescence spectroscopy is among the techniques used most frequently in laboratories to analyze compositions of chemical and biological samples. Heretofore, it has been possible to measure fluorescence spectra of molecular species at relative concentrations as low as parts per billion (ppb), with a few nm spectral resolution. The proposed instrument would include a planar array (mosaic) of detectors, onto which a fluorescence spectrum would be spatially mapped. Unlike in the larger laboratory-type molecular fluorescence spectrometers, mapping of wavelengths to spatial positions would be accomplished without use of relatively bulky optical parts. The proposed instrument is expected to be sensitive enough to enable measurement of spectra of chemical species at relative concentrations <1 ppb, with spectral resolution that could be tailored by design to be comparable to a laboratory molecular fluorescence spectrometer. The proposed instrument (see figure) would include a button-cell battery and a laser diode, which would generate the monochromatic ultraviolet light needed to excite fluorescence in a sample. The sample would be held in a cell bounded by far-ultraviolet-transparent quartz or optical glass. The detector array would be, more specifically, a complementary metal oxide/ semiconductor or charge-coupled- device imaging photodetector array, the photodetectors of which would be tailored to respond to light in the wavelength range of the fluorescence spectrum to be measured. The light-input face of the photodetector array would be covered with a matching checkerboard array of multilayer thin film interference filters, such that each pixel in the array would be sensitive only to light in a spectral band narrow enough so as not to overlap significantly with the band of an adjacent pixel. The wavelength interval between adjacent pixels (and, thus, the spectral resolution) would typically be chosen by design to be approximately equal to the width of the total fluorescence wavelength range of interest divided by the number of pixels. The unitary structure comprising the photodetector array overlaid with the matching filter array would be denoted a hyperspectral mosaic detector (HMD) array.

Toward VIP-PIX: A Low Noise Readout ASIC for Pixelated CdTe Gamma-Ray Detectors for Use in the Next Generation of PET Scanners.

PubMed

Macias-Montero, Jose-Gabriel; Sarraj, Maher; Chmeissani, Mokhtar; Puigdengoles, Carles; Lorenzo, Gianluca De; Martínez, Ricardo

2013-08-01

VIP-PIX will be a low noise and low power pixel readout electronics with digital output for pixelated Cadmium Telluride (CdTe) detectors. The proposed pixel will be part of a 2D pixel-array detector for various types of nuclear medicine imaging devices such as positron-emission tomography (PET) scanners, Compton gamma cameras, and positron-emission mammography (PEM) scanners. Each pixel will include a SAR ADC that provides the energy deposited with 10-bit resolution. Simultaneously, the self-triggered pixel which will be connected to a global time-to-digital converter (TDC) with 1 ns resolution will provide the event's time stamp. The analog part of the readout chain and the ADC have been fabricated with TSMC 0.25 μ m mixed-signal CMOS technology and characterized with an external test pulse. The power consumption of these parts is 200 μ W from a 2.5 V supply. It offers 4 switchable gains from ±10 mV/fC to ±40 mV/fC and an input charge dynamic range of up to ±70 fC for the minimum gain for both polarities. Based on noise measurements, the expected equivalent noise charge (ENC) is 65 e - RMS at room temperature.

Wafer-scale pixelated detector system

DOEpatents

Fahim, Farah; Deptuch, Grzegorz; Zimmerman, Tom

2017-10-17

A large area, gapless, detection system comprises at least one sensor; an interposer operably connected to the at least one sensor; and at least one application specific integrated circuit operably connected to the sensor via the interposer wherein the detection system provides high dynamic range while maintaining small pixel area and low power dissipation. Thereby the invention provides methods and systems for a wafer-scale gapless and seamless detector systems with small pixels, which have both high dynamic range and low power dissipation.

The first bump-bonded pixel detectors on CVD diamond

NASA Astrophysics Data System (ADS)

Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P. F.; Manfredotti, C.; Marshall, R. D.; Meier, D.; Mishina, M.; Oh, A.; Palmieri, V. G.; Pan, L. S.; Peitz, A.; Pernicka, M.; Pirollo, S.; Polesello, P.; Pretzl, K.; Re, V.; Riester, J. L.; Roe, S.; Roff, D.; Rudge, A.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Steuerer, J.; Stone, R.; Tapper, R. J.; Tesarek, R.; Trawick, M.; Trischuk, W.; Turchetta, R.; Vittone, E.; Wagner, A.; Walsh, A. M.; Wedenig, R.; Weilhammer, P.; Zeuner, W.; Ziock, H.; Zoeller, M.; Charles, E.; Ciocio, A.; Dao, K.; Einsweiler, K.; Fasching, D.; Gilchriese, M.; Joshi, A.; Kleinfelder, S.; Milgrome, O.; Palaio, N.; Richardson, J.; Sinervo, P.; Zizka, G.; RD42 Collaboration

1999-11-01

Diamond is a nearly ideal material for detecting ionising radiation. Its outstanding radiation hardness, fast charge collection and low leakage current allow it to be used in high radiation environments. These characteristics make diamond sensors particularly appealing for use in the next generation of pixel detectors. Over the last year, the RD42 collaboration has worked with several groups that have developed pixel readout electronics in order to optimise diamond sensors for bump-bonding. This effort resulted in an operational diamond pixel sensor that was tested in a pion beam. We demonstrate that greater than 98% of the channels were successfully bump-bonded and functioning. The device shows good overall hit efficiency as well as clear spatial hit correlation to tracks measured in a silicon reference telescope. A position resolution of 14.8 μm was observed, consistent with expectations given the detector pitch.

High-resolution pulse-counting array detectors for imaging and spectroscopy at ultraviolet wavelengths

NASA Technical Reports Server (NTRS)

Timothy, J. Gethyn; Bybee, Richard L.

1986-01-01

The performance characteristics of multianode microchannel array (MAMA) detector systems which have formats as large as 256 x 1024 pixels and which have application to imaging and spectroscopy at UV wavelengths are evaluated. Sealed and open-structure MAMA detector tubes with opaque CsI photocathodes can determine the arrival time of the detected photon to an accuracy of 100 ns or better. Very large format MAMA detectors with CsI and Cs2Te photocathodes and active areas of 52 x 52 mm (2048 x 2048 pixels) will be used as the UV solar blind detectors for the NASA STIS.

Spectral correction algorithm for multispectral CdTe x-ray detectors

NASA Astrophysics Data System (ADS)

Christensen, Erik D.; Kehres, Jan; Gu, Yun; Feidenhans'l, Robert; Olsen, Ulrik L.

2017-09-01

Compared to the dual energy scintillator detectors widely used today, pixelated multispectral X-ray detectors show the potential to improve material identification in various radiography and tomography applications used for industrial and security purposes. However, detector effects, such as charge sharing and photon pileup, distort the measured spectra in high flux pixelated multispectral detectors. These effects significantly reduce the detectors' capabilities to be used for material identification, which requires accurate spectral measurements. We have developed a semi analytical computational algorithm for multispectral CdTe X-ray detectors which corrects the measured spectra for severe spectral distortions caused by the detector. The algorithm is developed for the Multix ME100 CdTe X-ray detector, but could potentially be adapted for any pixelated multispectral CdTe detector. The calibration of the algorithm is based on simple attenuation measurements of commercially available materials using standard laboratory sources, making the algorithm applicable in any X-ray setup. The validation of the algorithm has been done using experimental data acquired with both standard lab equipment and synchrotron radiation. The experiments show that the algorithm is fast, reliable even at X-ray flux up to 5 Mph/s/mm2, and greatly improves the accuracy of the measured X-ray spectra, making the algorithm very useful for both security and industrial applications where multispectral detectors are used.

Modulation transfer function measurement technique for small-pixel detectors

NASA Technical Reports Server (NTRS)

Marchywka, Mike; Socker, Dennis G.

1992-01-01

A modulation transfer function (MTF) measurement technique suitable for large-format, small-pixel detector characterization has been investigated. A volume interference grating is used as a test image instead of the bar or sine wave target images normally used. This technique permits a high-contrast, large-area, sinusoidal intensity distribution to illuminate the device being tested, avoiding the need to deconvolve raw data with imaging system characteristics. A high-confidence MTF result at spatial frequencies near 200 cycles/mm is obtained. We present results at several visible light wavelengths with a 6.8-micron-pixel CCD. Pixel response functions are derived from the MTF results.

Single photon detection using Geiger mode CMOS avalanche photodiodes

NASA Astrophysics Data System (ADS)

Lawrence, William G.; Stapels, Christopher; Augustine, Frank L.; Christian, James F.

2005-10-01

Geiger mode Avalanche Photodiodes fabricated using complementary metal-oxide-semiconductor (CMOS) fabrication technology combine high sensitivity detectors with pixel-level auxiliary circuitry. Radiation Monitoring Devices has successfully implemented CMOS manufacturing techniques to develop prototype detectors with active diameters ranging from 5 to 60 microns and measured detection efficiencies of up to 60%. CMOS active quenching circuits are included in the pixel layout. The actively quenched pixels have a quenching time less than 30 ns and a maximum count rate greater than 10 MHz. The actively quenched Geiger mode avalanche photodiode (GPD) has linear response at room temperature over six orders of magnitude. When operating in Geiger mode, these GPDs act as single photon-counting detectors that produce a digital output pulse for each photon with no associated read noise. Thermoelectrically cooled detectors have less than 1 Hz dark counts. The detection efficiency, dark count rate, and after-pulsing of two different pixel designs are measured and demonstrate the differences in the device operation. Additional applications for these devices include nuclear imaging and replacement of photomultiplier tubes in dosimeters.

Prototypes and system test stands for the Phase 1 upgrade of the CMS pixel detector

DOE PAGES

Hasegawa, S.

2016-04-23

The CMS pixel phase-1 upgrade project replaces the current pixel detector with an upgraded system with faster readout electronics during the extended year-end technical stop of 2016/2017. New electronics prototypes for the system have been developed, and tests in a realistic environment for a comprehensive evaluation are needed. A full readout test stand with either the same hardware as used in the current CMS pixel detector or the latest prototypes of upgrade electronics has been built. The setup enables the observation and investigation of a jitter increase in the data line associated with trigger rate increases. This effect is duemore » to the way in which the clock and trigger distribution is implemented in CMS. A new prototype of the electronics with a PLL based on a voltage controlled quartz crystal oscillator (QPLL), which works as jitter filter, in the clock distribution path was produced. With the test stand, it was confirmed that the jitter increase is not seen with the prototype, and also good performance was confirmed at the expected detector operation temperature ($-$20 °C).« less

Charge collection properties in an irradiated pixel sensor built in a thick-film HV-SOI process

NASA Astrophysics Data System (ADS)

Hiti, B.; Cindro, V.; Gorišek, A.; Hemperek, T.; Kishishita, T.; Kramberger, G.; Krüger, H.; Mandić, I.; Mikuž, M.; Wermes, N.; Zavrtanik, M.

2017-10-01

Investigation of HV-CMOS sensors for use as a tracking detector in the ATLAS experiment at the upgraded LHC (HL-LHC) has recently been an active field of research. A potential candidate for a pixel detector built in Silicon-On-Insulator (SOI) technology has already been characterized in terms of radiation hardness to TID (Total Ionizing Dose) and charge collection after a moderate neutron irradiation. In this article we present results of an extensive irradiation hardness study with neutrons up to a fluence of 1× 1016 neq/cm2. Charge collection in a passive pixelated structure was measured by Edge Transient Current Technique (E-TCT). The evolution of the effective space charge concentration was found to be compliant with the acceptor removal model, with the minimum of the space charge concentration being reached after 5× 1014 neq/cm2. An investigation of the in-pixel uniformity of the detector response revealed parasitic charge collection by the epitaxial silicon layer characteristic for the SOI design. The results were backed by a numerical simulation of charge collection in an equivalent detector layout.

The Belle-II Depfet Pixel Detector at the Superkekb Flavour Factory

NASA Astrophysics Data System (ADS)

Heindl, Stefan

2012-08-01

The ongoing upgrade of the asymmetric electron positron collider KEKB also requires extensive detector upgrades to cope with the new design luminosity of 8 · 1035 cm-2 · s-1 · Of critical importance is the new silicon pixel vertex tracker, which will significantly improve the decay vertex resolution, crucial for time dependent CP violation measurements. This new detector will consist of two layers of DEPFET pixel seii8ors very close to the interaction point. These sensors combine both particle detection and amplification of the signal by embedding a field effect transistor into a 75 μm thick fully depleted silicon substrate, providing very high signal to noise ratios and excellent spatial resolution. Using this technology satisfies the given requirements of extremely low material and high radiation tolerance at the new Belle II experiment. The power dissipation due to continuous readout at high rate and spatial constraints also give strict requirements for the mechanical support and cooling of the new detector. We will discuss the overall concept of the pixel vertex tracker, its expected performance and the challenging mechanical integration.

Charge Loss and Charge Sharing Measurements for Two Different Pixelated Cadmium-Zinc-Telluride Detectors

NASA Technical Reports Server (NTRS)

Gaskin, Jessica; Sharma, Dharma; Ramsey, Brian; Seller, Paul

2003-01-01

As part of ongoing research at Marshall Space Flight Center, Cadmium-Zinc- Telluride (CdZnTe) pixilated detectors are being developed for use at the focal plane of the High Energy Replicated Optics (HERO) telescope. HERO requires a 64x64 pixel array with a spatial resolution of around 200 microns (with a 6m focal length) and high energy resolution (< 2% at 60keV). We are currently testing smaller arrays as a necessary first step towards this goal. In this presentation, we compare charge sharing and charge loss measurements between two devices that differ both electronically and geometrically. The first device consists of a 1-mm-thick piece of CdZnTe that is sputtered with a 4x4 array of pixels with pixel pitch of 750 microns (inter-pixel gap is 100 microns). The signal is read out using discrete ultra-low-noise preamplifiers, one for each of the 16 pixels. The second detector consists of a 2-mm-thick piece of CdZnTe that is sputtered with a 16x16 array of pixels with a pixel pitch of 300 microns (inter-pixel gap is 50 microns). Instead of using discrete preamplifiers, the crystal is bonded to an ASIC that provides all of the front-end electronics to each of the 256 pixels. what degree the bias voltage (i.e. the electric field) and hence the drift and diffusion coefficients affect our measurements. Further, we compare the measured results with simulated results and discuss to

The NUC and blind pixel eliminating in the DTDI application

NASA Astrophysics Data System (ADS)

Su, Xiao Feng; Chen, Fan Sheng; Pan, Sheng Da; Gong, Xue Yi; Dong, Yu Cui

2013-12-01

AS infrared CMOS Digital TDI (Time Delay and integrate) has a simple structure, excellent performance and flexible operation, it has been used in more and more applications. Because of the limitation of the Production process level, the plane array of the infrared detector has a large NU (non-uniformity) and a certain blind pixel rate. Both of the two will raise the noise and lead to the TDI works not very well. In this paper, for the impact of the system performance, the most important elements are analyzed, which are the NU of the optical system, the NU of the Plane array and the blind pixel in the Plane array. Here a reasonable algorithm which considers the background removal and the linear response model of the infrared detector is used to do the NUC (Non-uniformity correction) process, when the infrared detector array is used as a Digital TDI. In order to eliminate the impact of the blind pixel, the concept of surplus pixel method is introduced in, through the method, the SNR (signal to noise ratio) can be improved and the spatial and temporal resolution will not be changed. Finally we use a MWIR (Medium Ware Infrared) detector to do the experiment and the result proves the effectiveness of the method.

CdTe focal plane detector for hard x-ray focusing optics

NASA Astrophysics Data System (ADS)

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

2015-08-01

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 mm x 20 mm CdTe-based detector with 250 μm square pixels (80x80 pixels) which achieves 1 keV FWHM @ 60 keV and gives full spectroscopy between 5 keV and 200 keV. An added advantage of these detectors is that they have a full-frame readout rate of 10 kHz. Working with NASA Goddard Space Flight Center and Marshall Space Flight Center, 4 of these 1mm-thick CdTe detectors are tiled into a 2x2 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 flightsuitable 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.

CdTe Focal Plane Detector for Hard X-Ray Focusing Optics

NASA Technical Reports Server (NTRS)

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.

Silicon technologies for the CLIC vertex detector

NASA Astrophysics Data System (ADS)

Spannagel, S.

2017-06-01

CLIC is a proposed linear e+e- collider designed to provide particle collisions at center-of-mass energies of up to 3 TeV. Precise measurements of the properties of the top quark and the Higgs boson, as well as searches for Beyond the Standard Model physics require a highly performant CLIC detector. In particular the vertex detector must provide a single point resolution of only a few micrometers while not exceeding the envisaged material budget of around 0.2% X0 per layer. Beam-beam interactions and beamstrahlung processes impose an additional requirement on the timestamping capabilities of the vertex detector of about 10 ns. These goals can only be met by using novel techniques in the sensor and ASIC design as well as in the detector construction. The R&D program for the CLIC vertex detector explores various technologies in order to meet these demands. The feasibility of planar sensors with a thickness of 50-150 μm, including different active edge designs, are evaluated using Timepix3 ASICs. First prototypes of the CLICpix readout ASIC, implemented in 65 nm CMOS technology and with a pixel size of 25×25μm 2, have been produced and tested in particle beams. An updated version of the ASIC with a larger pixel matrix and improved precision of the time-over-threshold and time-of-arrival measurements has been submitted. Different hybridization concepts have been developed for the interconnection between the sensor and readout ASIC, ranging from small-pitch bump bonding of planar sensors to capacitive coupling of active HV-CMOS sensors. Detector simulations based on Geant 4 and TCAD are compared with experimental results to assess and optimize the performance of the various designs. This contribution gives an overview of the R&D program undertaken for the CLIC vertex detector and presents performance measurements of the prototype detectors currently under investigation.

50 μm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis.

PubMed

Zhao, C; Konstantinidis, A C; Zheng, Y; Anaxagoras, T; Speller, R D; Kanicki, J

2015-12-07

Wafer-scale CMOS active pixel sensors (APSs) have been developed recently for x-ray imaging applications. The small pixel pitch and low noise are very promising properties for medical imaging applications such as digital breast tomosynthesis (DBT). In this work, we evaluated experimentally and through modeling the imaging properties of a 50 μm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). A modified cascaded system model was developed for CMOS APS x-ray detectors by taking into account the device nonlinear signal and noise properties. The imaging properties such as modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) were extracted from both measurements and the nonlinear cascaded system analysis. The results show that the DynAMITe x-ray detector achieves a high spatial resolution of 10 mm(-1) and a DQE of around 0.5 at spatial frequencies  <1 mm(-1). In addition, the modeling results were used to calculate the image signal-to-noise ratio (SNRi) of microcalcifications at various mean glandular dose (MGD). For an average breast (5 cm thickness, 50% glandular fraction), 165 μm microcalcifications can be distinguished at a MGD of 27% lower than the clinical value (~1.3 mGy). To detect 100 μm microcalcifications, further optimizations of the CMOS APS x-ray detector, image aquisition geometry and image reconstruction techniques should be considered.

Precision tracking with a single gaseous pixel detector

NASA Astrophysics Data System (ADS)

Tsigaridas, S.; van Bakel, N.; Bilevych, Y.; Gromov, V.; Hartjes, F.; Hessey, N. P.; de Jong, P.; Kluit, R.

2015-09-01

The importance of micro-pattern gaseous detectors has grown over the past few years after successful usage in a large number of applications in physics experiments and medicine. We develop gaseous pixel detectors using micromegas-based amplification structures on top of CMOS pixel readout chips. Using wafer post-processing we add a spark-protection layer and a grid to create an amplification region above the chip, allowing individual electrons released above the grid by the passage of ionising radiation to be recorded. The electron creation point is measured in 3D, using the pixel position for (x, y) and the drift time for z. The track can be reconstructed by fitting a straight line to these points. In this work we have used a pixel-readout-chip which is a small-scale prototype of Timepix3 chip (designed for both silicon and gaseous detection media). This prototype chip has several advantages over the existing Timepix chip, including a faster front-end (pre-amplifier and discriminator) and a faster TDC which reduce timewalk's contribution to the z position error. Although the chip is very small (sensitive area of 0.88 × 0.88mm2), we have built it into a detector with a short drift gap (1.3 mm), and measured its tracking performance in an electron beam at DESY. We present the results obtained, which lead to a significant improvement for the resolutions with respect to Timepix-based detectors.

Developing fine-pixel CdTe detectors for the next generation of high-resolution hard x-ray telescopes

NASA Astrophysics Data System (ADS)

Christe, Steven

Over the past decade, the NASA Marshall Space Flight Center (MSFC) has been improving the angular resolution of hard X-ray (HXR; 20 "70 keV) optics to the point that we now routinely manufacture optics modules with an angular resolution of 20 arcsec Half Power Diameter (HDP), almost three times the performance of NuSTAR optics (Ramsey et al. 2013; Gubarev et al. 2013a; Atkins et al. 2013). New techniques are currently being developed to provide even higher angular resolution. 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. Excessively over-sampling the PSF will increase readout noise and require more processing with no appreciable increase in image quality. An appropriate level of over-sampling is to have 3 pixels within the HPD. For the HERO mirrors, where the HPD is 26 arcsec over a 6-m focal length converts to 750 μm, the optimum pixel size is around 250 μm. At a 10-m focal length these detectors can support a 16 arcsec HPD. Of course, the detectors must also have high efficiency in the HXR region, good energy resolution, low background, low power requirements, and low sensitivity to radiation damage (Ramsey 2001). The ability to handle high counting rates is also desirable for efficient calibration. A collaboration between Goddard Space Flight Center (GSFC), MSFC, and Rutherford Appleton Laboratory (RAL) in the UK is developing precisely such detectors under an ongoing, funded APRA program (FY2015 to FY2017). The detectors use the RALdeveloped Application Specific Integrated Circuit (ASIC) dubbed HEXITEC, for High Energy X-Ray Imaging Technology. These HEXITEC ASICs can be bonded to 1- or 2- mm-thick Cadmium Telluride (CdTe) or Cadmium-Zinc-Telluride (CZT) to create a fine (250 μm pitch) HXR detector (Jones et al. 2009; Seller et al. 2011). The objectives of this funded effort are to develop and test a HEXITEC-based detector system through the (1) design, manufacture, and test of front-end electronics instrument boards and (2) calibration of the detectors to assess their performance and (3) vibration and environmental testing. By the end of this program, multiple detector assemblies will be built and characterized, and can be used as part of future instruments. We propose to augment the existing effort with the development of an anti-coincidence shield for these HEXITEC-based detector assemblies to maximize sensitivity. Designing the anti-coincidence shield is enabled by the addition of a new team member, Wayne Baumgartner, who has recently and fortuitously joined the existing effort. Dr. Baumgartner has valuable and relevant past experience with a similar shield systems developed for NuSTAR and the InFOCμS x-ray telescope. We are asking for a modest amount of additional funding in this proposal year, as it coincides with a key time in the characterization and environmental testing of the detector assemblies. Characterization and environmental testing of the bare assemblies is already funded under the current effort. The addition of this active shield will allow for a more complete detector module vibration and environment test at the end of the existing development program so that this project results in a detector system with a demonstrated TRL of 6: "System/subsystem model or prototype demonstration in a relevant environment."

Spectral characterisation and noise performance of Vanilla—an active pixel sensor

NASA Astrophysics Data System (ADS)

Blue, Andrew; Bates, R.; Bohndiek, S. E.; Clark, A.; Arvanitis, Costas D.; Greenshaw, T.; Laing, A.; Maneuski, D.; Turchetta, R.; O'Shea, V.

2008-06-01

This work will report on the characterisation of a new active pixel sensor, Vanilla. The Vanilla comprises of 512×512 (25μm 2) pixels. The sensor has a 12 bit digital output for full-frame mode, although it can also be readout in analogue mode, whereby it can also be read in a fully programmable region-of-interest (ROI) mode. In full frame, the sensor can operate at a readout rate of more than 100 frames per second (fps), while in ROI mode, the speed depends on the size, shape and number of ROIs. For example, an ROI of 6×6 pixels can be read at 20,000 fps in analogue mode. Using photon transfer curve (PTC) measurements allowed for the calculation of the read noise, shot noise, full-well capacity and camera gain constant of the sensor. Spectral response measurements detailed the quantum efficiency (QE) of the detector through the UV and visible region. Analysis of the ROI readout mode was also performed. Such measurements suggest that the Vanilla APS (active pixel sensor) will be suitable for a wide range of applications including particle physics and medical imaging.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Altunbas, Cem, E-mail: caltunbas@gmail.com; Lai, Chao-Jen; Zhong, Yuncheng

Purpose: In using flat panel detectors (FPD) for cone beam computed tomography (CBCT), pixel gain variations may lead to structured nonuniformities in projections and ring artifacts in CBCT images. Such gain variations can be caused by change in detector entrance exposure levels or beam hardening, and they are not accounted by conventional flat field correction methods. In this work, the authors presented a method to identify isolated pixel clusters that exhibit gain variations and proposed a pixel gain correction (PGC) method to suppress both beam hardening and exposure level dependent gain variations. Methods: To modulate both beam spectrum and entrancemore » exposure, flood field FPD projections were acquired using beam filters with varying thicknesses. “Ideal” pixel values were estimated by performing polynomial fits in both raw and flat field corrected projections. Residuals were calculated by taking the difference between measured and ideal pixel values to identify clustered image and FPD artifacts in flat field corrected and raw images, respectively. To correct clustered image artifacts, the ratio of ideal to measured pixel values in filtered images were utilized as pixel-specific gain correction factors, referred as PGC method, and they were tabulated as a function of pixel value in a look-up table. Results: 0.035% of detector pixels lead to clustered image artifacts in flat field corrected projections, where 80% of these pixels were traced back and linked to artifacts in the FPD. The performance of PGC method was tested in variety of imaging conditions and phantoms. The PGC method reduced clustered image artifacts and fixed pattern noise in projections, and ring artifacts in CBCT images. Conclusions: Clustered projection image artifacts that lead to ring artifacts in CBCT can be better identified with our artifact detection approach. When compared to the conventional flat field correction method, the proposed PGC method enables characterization of nonlinear pixel gain variations as a function of change in x-ray spectrum and intensity. Hence, it can better suppress image artifacts due to beam hardening as well as artifacts that arise from detector entrance exposure variation.« less

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

PubMed Central

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.

2016-01-01

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 (<100 eV) with no active cooling. The 48 × 48 pixels JUNGFRAU 0.4 prototype can be combined with a charge-sharing suppression mask directly placed on the sensor, which keeps photons from hitting the charge-sharing regions of the pixels. The mask consists of a 150 µm tungsten sheet, in which 28 µm-diameter holes are laser-drilled. The mask is aligned with the pixels. The noise and gain characterization, and single-photon detection as low as 1.2 keV are shown. The performance of JUNGFRAU 0.4 without the mask and also in the charge-sharing suppression configuration (with the mask, with a ‘software mask’ or a ‘cluster finding’ algorithm) is tested, compared and evaluated, in particular with respect to the removal of the charge-sharing contribution in the spectra, the detection efficiency and the photon rate capability. Energy-dispersive and imaging experiments with fluorescence 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. PMID:26917124

a Portable Pixel Detector Operating as AN Active Nuclear Emulsion and its Application for X-Ray and Neutron Tomography

NASA Astrophysics Data System (ADS)

Vykydal, Z.; Jakubek, J.; Holy, T.; Pospisil, S.

2006-04-01

This work is devoted to the development of a USB1.1 (Universal Serial Bus) based read out system for the Medipix2 detector to achieve maximum portability of this position sensitive detecting device. All necessary detector support is integrated into one compact system (80 × 50 × 20 mm3) including the detector bias source (up to 100 V). The read out interface can control external I2C based devices, so in case of tomography it is easy to synchronize detector shutter with stepper motor control. An additional significant advantage of the USB interface is the support of back side pulse processing. This feature enables to determine the energy additionally to the position of a heavy charged particle hitting the sensor. Due to the small pixel dimensions it is also possible to distinguish the type of single quanta of radiation from the track created in the pixel detector as in case of an active nuclear emulsion.

Distributed Antenna-Coupled TES for FIR Detectors Arrays

NASA Technical Reports Server (NTRS)

Day, Peter K.; Leduc, Henry G.; Dowell, C. Darren; Lee, Richard A.; Zmuidzinas, Jonas

2007-01-01

We describe a new architecture for a superconducting detector for the submillimeter and far-infrared. This detector uses a distributed hot-electron transition edge sensor (TES) to collect the power from a focal-plane-filling slot antenna array. The sensors lay directly across the slots of the antenna and match the antenna impedance of about 30 ohms. Each pixel contains many sensors that are wired in parallel as a single distributed TES, which results in a low impedance that readily matches to a multiplexed SQUID readout These detectors are inherently polarization sensitive, with very low cross-polarization response, but can also be configured to sum both polarizations. The dual-polarization design can have a bandwidth of 50The use of electron-phonon decoupling eliminates the need for micro-machining, making the focal plane much easier to fabricate than with absorber-coupled, mechanically isolated pixels. We discuss applications of these detectors and a hybridization scheme compatible with arrays of tens of thousands of pixels.

ASIC Readout Circuit Architecture for Large Geiger Photodiode Arrays

NASA Technical Reports Server (NTRS)

Vasile, Stefan; Lipson, Jerold

2012-01-01

The objective of this work was to develop a new class of readout integrated circuit (ROIC) arrays to be operated with Geiger avalanche photodiode (GPD) arrays, by integrating multiple functions at the pixel level (smart-pixel or active pixel technology) in 250-nm CMOS (complementary metal oxide semiconductor) processes. In order to pack a maximum of functions within a minimum pixel size, the ROIC array is a full, custom application-specific integrated circuit (ASIC) design using a mixed-signal CMOS process with compact primitive layout cells. The ROIC array was processed to allow assembly in bump-bonding technology with photon-counting infrared detector arrays into 3-D imaging cameras (LADAR). The ROIC architecture was designed to work with either common- anode Si GPD arrays or common-cathode InGaAs GPD arrays. The current ROIC pixel design is hardwired prior to processing one of the two GPD array configurations, and it has the provision to allow soft reconfiguration to either array (to be implemented into the next ROIC array generation). The ROIC pixel architecture implements the Geiger avalanche quenching, bias, reset, and time to digital conversion (TDC) functions in full-digital design, and uses time domain over-sampling (vernier) to allow high temporal resolution at low clock rates, increased data yield, and improved utilization of the laser beam.

Variable pixel size ionospheric tomography

NASA Astrophysics Data System (ADS)

Zheng, Dunyong; Zheng, Hongwei; Wang, Yanjun; Nie, Wenfeng; Li, Chaokui; Ao, Minsi; Hu, Wusheng; Zhou, Wei

2017-06-01

A novel ionospheric tomography technique based on variable pixel size was developed for the tomographic reconstruction of the ionospheric electron density (IED) distribution. In variable pixel size computerized ionospheric tomography (VPSCIT) model, the IED distribution is parameterized by a decomposition of the lower and upper ionosphere with different pixel sizes. Thus, the lower and upper IED distribution may be very differently determined by the available data. The variable pixel size ionospheric tomography and constant pixel size tomography are similar in most other aspects. There are some differences between two kinds of models with constant and variable pixel size respectively, one is that the segments of GPS signal pay should be assigned to the different kinds of pixel in inversion; the other is smoothness constraint factor need to make the appropriate modified where the pixel change in size. For a real dataset, the variable pixel size method distinguishes different electron density distribution zones better than the constant pixel size method. Furthermore, it can be non-chided that when the effort is spent to identify the regions in a model with best data coverage. The variable pixel size method can not only greatly improve the efficiency of inversion, but also produce IED images with high fidelity which are the same as a used uniform pixel size method. In addition, variable pixel size tomography can reduce the underdetermined problem in an ill-posed inverse problem when the data coverage is irregular or less by adjusting quantitative proportion of pixels with different sizes. In comparison with constant pixel size tomography models, the variable pixel size ionospheric tomography technique achieved relatively good results in a numerical simulation. A careful validation of the reliability and superiority of variable pixel size ionospheric tomography was performed. Finally, according to the results of the statistical analysis and quantitative comparison, the proposed method offers an improvement of 8% compared with conventional constant pixel size tomography models in the forward modeling.

Small-angle solution scattering using the mixed-mode pixel array detector

PubMed Central

Koerner, Lucas J.; Gillilan, Richard E.; Green, Katherine S.; Wang, Suntao; Gruner, Sol M.

2011-01-01

Solution small-angle X-ray scattering (SAXS) measurements were obtained using a 128 × 128 pixel X-ray mixed-mode pixel array detector (MMPAD) with an 860 µs readout time. The MMPAD offers advantages for SAXS experiments: a pixel full-well of >2 × 107 10 keV X-rays, a maximum flux rate of 108 X-rays pixel−1 s−1, and a sub-pixel point-spread function. Data from the MMPAD were quantitatively compared with data from a charge-coupled device (CCD) fiber-optically coupled to a phosphor screen. MMPAD solution SAXS data from lysozyme solutions were of equal or better quality than data captured by the CCD. The read-noise (normalized by pixel area) of the MMPAD was less than that of the CCD by an average factor of 3.0. Short sample-to-detector distances were required owing to the small MMPAD area (19.2 mm × 19.2 mm), and were revealed to be advantageous with respect to detector read-noise. As predicted by the Shannon sampling theory and confirmed by the acquisition of lysozyme solution SAXS curves, the MMPAD at short distances is capable of sufficiently sampling a solution SAXS curve for protein shape analysis. The readout speed of the MMPAD was demonstrated by continuously monitoring lysozyme sample evolution as radiation damage accumulated. These experiments prove that a small suitably configured MMPAD is appropriate for time-resolved solution scattering measurements. PMID:21335900

X-ray tests of a microchannel plate detector and amorphous silicon pixel array readout for neutron radiography

NASA Astrophysics Data System (ADS)

Ambrosi, R. M.; Street, R.; Feller, B.; Fraser, G. W.; Watterson, J. I. W.; Lanza, R. C.; Dowson, J.; Ross, D.; Martindale, A.; Abbey, A. F.; Vernon, D.

2007-03-01

High-performance large area imaging detectors for fast neutrons in the 5-14 MeV energy range do not exist at present. The aim of this project is to combine microchannel plates or MCPs (or similar electron multiplication structures) traditionally used in image intensifiers and X-ray detectors with amorphous silicon (a-Si) pixel arrays to produce a composite converter and intensifier position sensitive imaging system. This detector will provide an order of magnitude improvement in image resolution when compared with current millimetre resolution limits obtained using phosphor or scintillator-based hydrogen rich converters. In this study we present the results of the initial experimental evaluation of the prototype system. This study was carried out using a medical X-ray source for the proof of concept tests, the next phase will involve neutron imaging tests. The hybrid detector described in this study is a unique development and paves the way for large area position sensitive detectors consisting of MCP or microsphere plate detectors and a-Si or polysilicon pixel arrays. Applications include neutron and X-ray imaging for terrestrial applications. The technology could be extended to space instrumentation for X-ray astronomy.

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

NASA Astrophysics Data System (ADS)

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

2016-03-01

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

System design and simulation of a long-wave infrared hyperspectral imaging spectrometer

NASA Astrophysics Data System (ADS)

Yuan, Li-yin; Xu, Wei-ming; He, Zhi-ping; Lin, Ying; Shu, Rong; Wang, Jian-yu

2009-07-01

A ground-based long-wave hyperspectral imaging spectrometer (LWHIS) is designed and simulated. The spectrometer is based on a focal plane array detector with a spectral response that covers the range 7700 to 9300 nm. Optical system of this instrument is all-reflective and provides up to 30 continuous spectral channels with 54 nm of dispersion per pixel. The entrance aperture is 20 mm and feeds an F/2 telescope front end. The telescope has a 11-deg field of view with 256 spatially resolved elements (detector pixel size is 30 μm). To get high enough signal noise rate (SNR), no concern about the electronic part, first, the cool stop of the detector is used as soon as possible, and second, background thermal radiance of the opto-mechanical system seen by the focal plane must be suppressed. Thus, the entire instrument is set in a vacuum chamber and the opto-mechanical subsystem is cooled by liquid nitrogen. The background thermal radiance verse different cases is discussed. Based on the radiation simulation and analysis, if the opto-mechanical subsystem of the spectrometer within the vacuum chamber is cooled blew 100 Kelvin, significant performance gains can be realized. The design and simulation provides an example for illustrating the design principles specific and radiation simulation to this type of system.

Simultaneous fluorescence and quantitative phase microscopy with single-pixel detectors

NASA Astrophysics Data System (ADS)

Liu, Yang; Suo, Jinli; Zhang, Yuanlong; Dai, Qionghai

2018-02-01

Multimodal microscopy offers high flexibilities for biomedical observation and diagnosis. Conventional multimodal approaches either use multiple cameras or a single camera spatially multiplexing different modes. The former needs expertise demanding alignment and the latter suffers from limited spatial resolution. Here, we report an alignment-free full-resolution simultaneous fluorescence and quantitative phase imaging approach using single-pixel detectors. By combining reference-free interferometry with single-pixel detection, we encode the phase and fluorescence of the sample in two detection arms at the same time. Then we employ structured illumination and the correlated measurements between the sample and the illuminations for reconstruction. The recovered fluorescence and phase images are inherently aligned thanks to single-pixel detection. To validate the proposed method, we built a proof-of-concept setup for first imaging the phase of etched glass with the depth of a few hundred nanometers and then imaging the fluorescence and phase of the quantum dot drop. This method holds great potential for multispectral fluorescence microscopy with additional single-pixel detectors or a spectrometer. Besides, this cost-efficient multimodal system might find broad applications in biomedical science and neuroscience.

A fast event preprocessor for the Simbol-X Low-Energy Detector

NASA Astrophysics Data System (ADS)

Schanz, T.; Tenzer, C.; Kendziorra, E.; Santangelo, A.

2008-07-01

The Simbol-X1 Low Energy Detector (LED), a 128 × 128 pixel DEPFET array, will be read out very fast (8000 frames/second). This requires a very fast onboard data preprocessing of the raw data. We present an FPGA based Event Preprocessor (EPP) which can fulfill this requirements. The design is developed in the hardware description language VHDL and can be later ported on an ASIC technology. The EPP performs a pixel related offset correction and can apply different energy thresholds to each pixel of the frame. It also provides a line related common-mode correction to reduce noise that is unavoidably caused by the analog readout chip of the DEPFET. An integrated pattern detector can block all invalid pixel patterns. The EPP has an internal pipeline structure and can perform all operation in realtime (< 2 μs per line of 64 pixel) with a base clock frequency of 100 MHz. It is utilizing a fast median-value detection algorithm for common-mode correction and a new pattern scanning algorithm to select only valid events. Both new algorithms were developed during the last year at our institute.

An Efficient, FPGA-Based, Cluster Detection Algorithm Implementation for a Strip Detector Readout System in a Time Projection Chamber Polarimeter

NASA Technical Reports Server (NTRS)

Gregory, Kyle J.; Hill, Joanne E. (Editor); Black, J. Kevin; Baumgartner, Wayne H.; Jahoda, Keith

2016-01-01

A fundamental challenge in a spaceborne application of a gas-based Time Projection Chamber (TPC) for observation of X-ray polarization is handling the large amount of data collected. The TPC polarimeter described uses the APV-25 Application Specific Integrated Circuit (ASIC) to readout a strip detector. Two dimensional photoelectron track images are created with a time projection technique and used to determine the polarization of the incident X-rays. The detector produces a 128x30 pixel image per photon interaction with each pixel registering 12 bits of collected charge. This creates challenging requirements for data storage and downlink bandwidth with only a modest incidence of photons and can have a significant impact on the overall mission cost. An approach is described for locating and isolating the photoelectron track within the detector image, yielding a much smaller data product, typically between 8x8 pixels and 20x20 pixels. This approach is implemented using a Microsemi RT-ProASIC3-3000 Field-Programmable Gate Array (FPGA), clocked at 20 MHz and utilizing 10.7k logic gates (14% of FPGA), 20 Block RAMs (17% of FPGA), and no external RAM. Results will be presented, demonstrating successful photoelectron track cluster detection with minimal impact to detector dead-time.

Can direct electron detectors outperform phosphor-CCD systems for TEM?

NASA Astrophysics Data System (ADS)

Moldovan, G.; Li, X.; Kirkland, A.

2008-08-01

A new generation of imaging detectors is being considered for application in TEM, but which device architectures can provide the best images? Monte Carlo simulations of the electron-sensor interaction are used here to calculate the expected modulation transfer of monolithic active pixel sensors (MAPS), hybrid active pixel sensors (HAPS) and double sided Silicon strip detectors (DSSD), showing that ideal and nearly ideal transfer can be obtained using DSSD and MAPS sensors. These results highly recommend the replacement of current phosphor screen and charge coupled device imaging systems with such new directly exposed position sensitive electron detectors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeffrey A Appel

BTeV is a new Fermilab beauty and charm experiment designed to operate in the CZero region of the Tevatron collider. Critical to the success of BTeV is its pixel detector. The unique features of this pixel detector include its proximity to the beam, its operation with a beam crossing time of 132 ns, and the need for the detector information to be read out quickly enough to be used for the lowest level trigger. This talk presents an overview of the pixel detector design, giving the motivations for the technical choices made. The status of the current R&D on detectormore » components is also reviewed. Additional Pixel 2002 talks on the BTeV pixel detector are given by Dave Christian[1], Mayling Wong[2], and Sergio Zimmermann[3]. Table 1 gives a selection of pixel detector parameters for the ALICE, ATLAS, BTeV, and CMS experiments. Comparing the progression of this table, which I have been updating for the last several years, has shown a convergence of specifications. Nevertheless, significant differences endure. The BTeV data-driven readout, horizontal and vertical position resolution better than 9 {micro}m with the {+-} 300 mr forward acceptance, and positioning in vacuum and as close as 6 mm from the circulating beams remain unique. These features are driven by the physics goals of the BTeV experiment. Table 2 demonstrates that the vertex trigger performance made possible by these features is requisite for a very large fraction of the B meson decay physics which is so central to the motivation for BTeV. For most of the physics quantities of interest listed in the table, the vertex trigger is essential. The performance of the BTeV pixel detector may be summarized by looking at particular physics examples; e.g., the B{sub s} meson decay B{sub s} {yields} D{sub s}{sup -} K{sup +}. For that decay, studies using GEANT3 simulations provide quantitative measures of performance. For example, the separation between the B{sub s} decay point and the primary proton-antiproton interaction can be measured with an rms uncertainty of 138 {micro}m. This, with the uncertainty in the decay vertex position, leads to an uncertainty of the B{sub s} proper decay time of 46 fs. Even if the parameter x{sub s} equals 25 (where the current lower limit on x{sub s} is about 15), the corresponding relevant proper time is 400 fs. So, the detector resolution is more than adequate to make an excellent measurement of this parameter.« less

Multi-anode microchannel arrays. [for use in ground-based and spaceborne telescopes

NASA Technical Reports Server (NTRS)

Timothy, J. G.; Mount, G. H.; Bybee, R. L.

1979-01-01

The Multi-Anode Microchannel Arrays (MAMA's) are a family of photoelectric, photon-counting array detectors being developed for use in instruments on both ground-based and space-borne telescopes. These detectors combine high sensitivity and photometric stability with a high-resolution imaging capability. MAMA detectors can be operated in a windowless configuration at extreme-ultraviolet and soft X-ray wavelengths or in a sealed configuration at ultraviolet and visible wavelengths. Prototype MAMA detectors with up to 512 x 512 pixels are now being tested in the laboratory and telescope operation of a simple (10 x 10)-pixel visible-light detector has been initiated. The construction and modes-of-operation of the MAMA detectors are briefly described and performance data are presented.

An EUDET/AIDA Pixel Beam Telescope for Detector Development

NASA Astrophysics Data System (ADS)

Rubinskiy, I.; EUDET Consortium; AIDA Consortium

Ahigh resolution(σ< 2 μm) beam telescope based on monolithic active pixel sensors (MAPS) was developed within the EUDET collaboration. EUDET was a coordinated detector R&D programme for the future International Linear Collider providing test beam infrastructure to detector R&D groups. The telescope consists of six sensor planes with a pixel pitch of either 18.4 μm or 10 μmand canbe operated insidea solenoidal magnetic fieldofupto1.2T.Ageneral purpose cooling, positioning, data acquisition (DAQ) and offine data analysis tools are available for the users. The excellent resolution, readout rate andDAQintegration capabilities made the telescopea primary beam tests tool also for several CERN based experiments. In this report the performance of the final telescope is presented. The plans for an even more flexible telescope with three differentpixel technologies(ATLASPixel, Mimosa,Timepix) withinthenew European detector infrastructure project AIDA are presented.

Performance improvements of wavelength-shifting-fiber neutron detectors using high-resolution positioning algorithms

DOE PAGES

Wang, C. L.

2016-05-17

On the basis of FluoroBancroft linear-algebraic method [S.B. Andersson, Opt. Exp. 16, 18714 (2008)] three highly-resolved positioning methods were proposed for wavelength-shifting fiber (WLSF) neutron detectors. Using a Gaussian or exponential-decay light-response function (LRF), the non-linear relation of photon-number profiles vs. x-pixels was linearized and neutron positions were determined. The proposed algorithms give an average 0.03-0.08 pixel position error, much smaller than that (0.29 pixel) from a traditional maximum photon algorithm (MPA). The new algorithms result in better detector uniformity, less position misassignment (ghosting), better spatial resolution, and an equivalent or better instrument resolution in powder diffraction than the MPA.more » Moreover, these characters will facilitate broader applications of WLSF detectors at time-of-flight neutron powder diffraction beamlines, including single-crystal diffraction and texture analysis.« less

Infrared spectro-polarimeter on the Solar Flare Telescope at NAOJ/Mitaka

NASA Astrophysics Data System (ADS)

Sakurai, Takashi; Hanaoka, Yoichiro; Arai, Takehiko; Hagino, Masaoki; Kawate, Tomoko; Kitagawa, Naomasa; Kobiki, Toshihiko; Miyashita, Masakuni; Morita, Satoshi; Otsuji, Ken'ichi; Shinoda, Kazuya; Suzuki, Isao; Yaji, Kentaro; Yamasaki, Takayuki; Fukuda, Takeo; Noguchi, Motokazu; Takeyama, Norihide; Kanai, Yoshikazu; Yamamuro, Tomoyasu

2018-05-01

An infrared spectro-polarimeter installed on the Solar Flare Telescope at the Mitaka headquarters of the National Astronomical Observatory of Japan is described. The new spectro-polarimeter observes the full Sun via slit scans performed at two wavelength bands, one near 1565 nm for a Zeeman-sensitive spectral line of Fe I and the other near 1083 nm for He I and Si I lines. The full Stokes profiles are recorded; the Fe I and Si I lines give information on photospheric vector magnetic fields, and the helium line is suitable for deriving chromospheric magnetic fields. The infrared detector we are using is an InGaAs camera with 640 × 512 pixels and a read-out speed of 90 frames s-1. The solar disk is covered by two swaths (the northern and southern hemispheres) of 640 pixels each. The final magnetic maps are made of 1200 × 1200 pixels with a pixel size of 1{^''.}8. We have been carrying out regular observations since 2010 April, and have provided full-disk, full-Stokes maps, at the rate of a few maps per day, on the internet.

Linear fitting of multi-threshold counting data with a pixel-array detector for spectral X-ray imaging

PubMed Central

Muir, Ryan D.; Pogranichney, Nicholas R.; Muir, J. Lewis; Sullivan, Shane Z.; Battaile, Kevin P.; Mulichak, Anne M.; Toth, Scott J.; Keefe, Lisa J.; Simpson, Garth J.

2014-01-01

Experiments and modeling are described to perform spectral fitting of multi-threshold counting measurements on a pixel-array detector. An analytical model was developed for describing the probability density function of detected voltage in X-ray photon-counting arrays, utilizing fractional photon counting to account for edge/corner effects from voltage plumes that spread across multiple pixels. Each pixel was mathematically calibrated by fitting the detected voltage distributions to the model at both 13.5 keV and 15.0 keV X-ray energies. The model and established pixel responses were then exploited to statistically recover images of X-ray intensity as a function of X-ray energy in a simulated multi-wavelength and multi-counting threshold experiment. PMID:25178010

Linear fitting of multi-threshold counting data with a pixel-array detector for spectral X-ray imaging.

PubMed

Muir, Ryan D; Pogranichney, Nicholas R; Muir, J Lewis; Sullivan, Shane Z; Battaile, Kevin P; Mulichak, Anne M; Toth, Scott J; Keefe, Lisa J; Simpson, Garth J

2014-09-01

Experiments and modeling are described to perform spectral fitting of multi-threshold counting measurements on a pixel-array detector. An analytical model was developed for describing the probability density function of detected voltage in X-ray photon-counting arrays, utilizing fractional photon counting to account for edge/corner effects from voltage plumes that spread across multiple pixels. Each pixel was mathematically calibrated by fitting the detected voltage distributions to the model at both 13.5 keV and 15.0 keV X-ray energies. The model and established pixel responses were then exploited to statistically recover images of X-ray intensity as a function of X-ray energy in a simulated multi-wavelength and multi-counting threshold experiment.

High resolution CsI(Tl)/Si-PIN detector development for breast imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patt, B.E.; Iwanczyk, J.S.; Tull, C.R.

High resolution multi-element (8x8) imaging arrays with collimators, size matched to discrete CsI(Tl) scintillator arrays and Si-PIN photodetector arrays (PDA`s) were developed as prototypes for larger arrays for breast imaging. Photodetector pixels were each 1.5 {times} 1.5 mm{sup 2} with 0.25 mm gaps. A 16-element quadrant of the detector was evaluated with a segmented CsI(Tl) scintillator array coupled to the silicon array. The scintillator thickness of 6 mm corresponds to >85% total gamma efficiency at 140 keV. Pixel energy resolution of <8% FWHM was obtained for Tc-99m. Electronic noise was 41 e{sup {minus}} RMS corresponding to a 3% FWHM contributionmore » to the 140 keV photopeak. Detection efficiency uniformity measured with a Tc-99m flood source was 4.3% for an {approximately}10% energy photopeak window. Spatial resolution was 1.53 mm FWHM and pitch was 1.75 mm as measured from the Co-57 (122 keV) line spread function. Signal to background was 34 and contrast was 0.94. The energy resolution and spatial characteristics of the new imaging detector exceed those of other scintillator based imaging detectors. A camera based on this technology will allow: (1) Improved Compton scatter rejection; (2) Detector positioning in close proximity to the breast to increase signal to noise; (3) Improved spatial resolution; and (4) Improved efficiency compared to high resolution collimated gamma cameras for the anticipated compressed breast geometries.« less

A GPU Simulation Tool for Training and Optimisation in 2D Digital X-Ray Imaging.

PubMed

Gallio, Elena; Rampado, Osvaldo; Gianaria, Elena; Bianchi, Silvio Diego; Ropolo, Roberto

2015-01-01

Conventional radiology is performed by means of digital detectors, with various types of technology and different performance in terms of efficiency and image quality. Following the arrival of a new digital detector in a radiology department, all the staff involved should adapt the procedure parameters to the properties of the detector, in order to achieve an optimal result in terms of correct diagnostic information and minimum radiation risks for the patient. The aim of this study was to develop and validate a software capable of simulating a digital X-ray imaging system, using graphics processing unit computing. All radiological image components were implemented in this application: an X-ray tube with primary beam, a virtual patient, noise, scatter radiation, a grid and a digital detector. Three different digital detectors (two digital radiography and a computed radiography systems) were implemented. In order to validate the software, we carried out a quantitative comparison of geometrical and anthropomorphic phantom simulated images with those acquired. In terms of average pixel values, the maximum differences were below 15%, while the noise values were in agreement with a maximum difference of 20%. The relative trends of contrast to noise ratio versus beam energy and intensity were well simulated. Total calculation times were below 3 seconds for clinical images with pixel size of actual dimensions less than 0.2 mm. The application proved to be efficient and realistic. Short calculation times and the accuracy of the results obtained make this software a useful tool for training operators and dose optimisation studies.

Charge-sensitive front-end electronics with operational amplifiers for CdZnTe detectors

NASA Astrophysics Data System (ADS)

Födisch, P.; Berthel, M.; Lange, B.; Kirschke, T.; Enghardt, W.; Kaever, P.

2016-09-01

Cadmium zinc telluride (CdZnTe, CZT) radiation detectors are suitable for a variety of applications, due to their high spatial resolution and spectroscopic energy performance at room temperature. However, state-of-the-art detector systems require high-performance readout electronics. Though an application-specific integrated circuit (ASIC) is an adequate solution for the readout, requirements of high dynamic range and high throughput are not available in any commercial circuit. Consequently, the present study develops the analog front-end electronics with operational amplifiers for an 8×8 pixelated CZT detector. For this purpose, we modeled an electrical equivalent circuit of the CZT detector with the associated charge-sensitive amplifier (CSA). Based on a detailed network analysis, the circuit design is completed by numerical values for various features such as ballistic deficit, charge-to-voltage gain, rise time, and noise level. A verification of the performance is carried out by synthetic detector signals and a pixel detector. The experimental results with the pixel detector assembly and a 22Na radioactive source emphasize the depth dependence of the measured energy. After pulse processing with depth correction based on the fit of the weighting potential, the energy resolution is 2.2% (FWHM) for the 511 keV photopeak.

A 64-pixel NbTiN superconducting nanowire single-photon detector array for spatially resolved photon detection.

PubMed

Miki, Shigehito; Yamashita, Taro; Wang, Zhen; Terai, Hirotaka

2014-04-07

We present the characterization of two-dimensionally arranged 64-pixel NbTiN superconducting nanowire single-photon detector (SSPD) array for spatially resolved photon detection. NbTiN films deposited on thermally oxidized Si substrates enabled the high-yield production of high-quality SSPD pixels, and all 64 SSPD pixels showed uniform superconducting characteristics within the small range of 7.19-7.23 K of superconducting transition temperature and 15.8-17.8 μA of superconducting switching current. Furthermore, all of the pixels showed single-photon sensitivity, and 60 of the 64 pixels showed a pulse generation probability higher than 90% after photon absorption. As a result of light irradiation from the single-mode optical fiber at different distances between the fiber tip and the active area, the variations of system detection efficiency (SDE) in each pixel showed reasonable Gaussian distribution to represent the spatial distributions of photon flux intensity.

Numerical simulation of the modulation transfer function (MTF) in infrared focal plane arrays: simulation methodology and MTF optimization

NASA Astrophysics Data System (ADS)

Schuster, J.

2018-02-01

Military requirements demand both single and dual-color infrared (IR) imaging systems with both high resolution and sharp contrast. To quantify the performance of these imaging systems, a key measure of performance, the modulation transfer function (MTF), describes how well an optical system reproduces an objects contrast in the image plane at different spatial frequencies. At the center of an IR imaging system is the focal plane array (FPA). IR FPAs are hybrid structures consisting of a semiconductor detector pixel array, typically fabricated from HgCdTe, InGaAs or III-V superlattice materials, hybridized with heat/pressure to a silicon read-out integrated circuit (ROIC) with indium bumps on each pixel providing the mechanical and electrical connection. Due to the growing sophistication of the pixel arrays in these FPAs, sophisticated modeling techniques are required to predict, understand, and benchmark the pixel array MTF that contributes to the total imaging system MTF. To model the pixel array MTF, computationally exhaustive 2D and 3D numerical simulation approaches are required to correctly account for complex architectures and effects such as lateral diffusion from the pixel corners. It is paramount to accurately model the lateral di_usion (pixel crosstalk) as it can become the dominant mechanism limiting the detector MTF if not properly mitigated. Once the detector MTF has been simulated, it is directly decomposed into its constituent contributions to reveal exactly what is limiting the total detector MTF, providing a path for optimization. An overview of the MTF will be given and the simulation approach will be discussed in detail, along with how different simulation parameters effect the MTF calculation. Finally, MTF optimization strategies (crosstalk mitigation) will be discussed.

Amorphous selenium direct detection CMOS digital x-ray imager with 25 micron pixel pitch

NASA Astrophysics Data System (ADS)

Scott, Christopher C.; Abbaszadeh, Shiva; Ghanbarzadeh, Sina; Allan, Gary; Farrier, Michael; Cunningham, Ian A.; Karim, Karim S.

2014-03-01

We have developed a high resolution amorphous selenium (a-Se) direct detection imager using a large-area compatible back-end fabrication process on top of a CMOS active pixel sensor having 25 micron pixel pitch. Integration of a-Se with CMOS technology requires overcoming CMOS/a-Se interfacial strain, which initiates nucleation of crystalline selenium and results in high detector dark currents. A CMOS-compatible polyimide buffer layer was used to planarize the backplane and provide a low stress and thermally stable surface for a-Se. The buffer layer inhibits crystallization and provides detector stability that is not only a performance factor but also critical for favorable long term cost-benefit considerations in the application of CMOS digital x-ray imagers in medical practice. The detector structure is comprised of a polyimide (PI) buffer layer, the a-Se layer, and a gold (Au) top electrode. The PI layer is applied by spin-coating and is patterned using dry etching to open the backplane bond pads for wire bonding. Thermal evaporation is used to deposit the a-Se and Au layers, and the detector is operated in hole collection mode (i.e. a positive bias on the Au top electrode). High resolution a-Se diagnostic systems typically use 70 to 100 μm pixel pitch and have a pre-sampling modulation transfer function (MTF) that is significantly limited by the pixel aperture. Our results confirm that, for a densely integrated 25 μm pixel pitch CMOS array, the MTF approaches the fundamental material limit, i.e. where the MTF begins to be limited by the a-Se material properties and not the pixel aperture. Preliminary images demonstrating high spatial resolution have been obtained from a frst prototype imager.

Ghost imaging based on Pearson correlation coefficients

NASA Astrophysics Data System (ADS)

Yu, Wen-Kai; Yao, Xu-Ri; Liu, Xue-Feng; Li, Long-Zhen; Zhai, Guang-Jie

2015-05-01

Correspondence imaging is a new modality of ghost imaging, which can retrieve a positive/negative image by simple conditional averaging of the reference frames that correspond to relatively large/small values of the total intensity measured at the bucket detector. Here we propose and experimentally demonstrate a more rigorous and general approach in which a ghost image is retrieved by calculating a Pearson correlation coefficient between the bucket detector intensity and the brightness at a given pixel of the reference frames, and at the next pixel, and so on. Furthermore, we theoretically provide a statistical interpretation of these two imaging phenomena, and explain how the error depends on the sample size and what kind of distribution the error obeys. According to our analysis, the image signal-to-noise ratio can be greatly improved and the sampling number reduced by means of our new method. Project supported by the National Key Scientific Instrument and Equipment Development Project of China (Grant No. 2013YQ030595) and the National High Technology Research and Development Program of China (Grant No. 2013AA122902).

Corrugated Quantum Well Infrared Photodetector Focal Plane Array Test Results

NASA Technical Reports Server (NTRS)

Goldberg, A.; Choi, K. K.; Das, N. C.; La, A.; Jhabvala, M.

1999-01-01

The corrugated quantum-well infrared photodetector (C-QWIP) uses total internal reflection to couple normal incident light into the optically active quantum wells. The coupling efficiency has been shown to be relatively independent of the pixel size and wavelength thus making the C-QWIP a candidate for detectors over the entire infrared spectrum. The broadband coupling efficiency of the C-QWIP makes it an ideal candidate for multiwavelength detectors. We fabricated and tested C-QWIP focal plane arrays (FPAs) with cutoff wavelengths of 11.2 and 16.2 micrometers. Each FPA has 256 x 256 pixels that are bump-bonded to a direct injection readout circuit. Both FPAs provided infrared imagery with good aesthetic attributes. For the 11.2-micrometers FPA, background-limited performance (BLIP) was observed at 60 K with f/3 optics. For the 16.2-micrometers FPA, BLIP was observed at 38 K. Besides the reduction of dark current in C-QWIP structures, the measured internal quantum efficiency (eta) remains to be high. The values for responsivity and quantum efficiency obtained from the FPA results agree well with those measured for single devices.

The phase 1 upgrade of the CMS Pixel Front-End Driver

NASA Astrophysics Data System (ADS)

Friedl, M.; Pernicka, M.; Steininger, H.

2010-12-01

The pixel detector of the CMS experiment at the LHC is read out by analog optical links, sending the data to 9U VME Front-End Driver (FED) boards located in the electronics cavern. There are plans for the phase 1 upgrade of the pixel detector (2016) to add one more layer, while significantly cutting down the overall material budget. At the same time, the optical data transmission will be replaced by a serialized digital scheme. A plug-in board solution with a high-speed digital optical receiver has been developed for the Pixel-FED readout boards and will be presented along with first tests of the future optical link.

The INFN-FBK pixel R&D program for HL-LHC

NASA Astrophysics Data System (ADS)

Meschini, M.; Dalla Betta, G. F.; Boscardin, M.; Calderini, G.; Darbo, G.; Giacomini, G.; Messineo, A.; Ronchin, S.

2016-09-01

We report on the ATLAS and CMS joint research activity, which is aiming at the development of new, thin silicon pixel detectors for the Large Hadron Collider Phase-2 detector upgrades. This R&D is performed under special agreement between Istituto Nazionale di Fisica Nucleare and FBK foundation (Trento, Italy). New generations of 3D and planar pixel sensors with active edges are being developed in the R&D project, and will be fabricated at FBK. A first planar pixel batch, which was produced by the end of year 2014, will be described in this paper. First clean room measurement results on planar sensors obtained before and after neutron irradiation will be presented.

Panoramic thermal imaging: challenges and tradeoffs

NASA Astrophysics Data System (ADS)

Aburmad, Shimon

2014-06-01

Over the past decade, we have witnessed a growing demand for electro-optical systems that can provide continuous 3600 coverage. Applications such as perimeter security, autonomous vehicles, and military warning systems are a few of the most common applications for panoramic imaging. There are several different technological approaches for achieving panoramic imaging. Solutions based on rotating elements do not provide continuous coverage as there is a time lag between updates. Continuous panoramic solutions either use "stitched" images from multiple adjacent sensors, or sophisticated optical designs which warp a panoramic view onto a single sensor. When dealing with panoramic imaging in the visible spectrum, high volume production and advancement of semiconductor technology has enabled the use of CMOS/CCD image sensors with a huge number of pixels, small pixel dimensions, and low cost devices. However, in the infrared spectrum, the growth of detector pixel counts, pixel size reduction, and cost reduction is taking place at a slower rate due to the complexity of the technology and limitations caused by the laws of physics. In this work, we will explore the challenges involved in achieving 3600 panoramic thermal imaging, and will analyze aspects such as spatial resolution, FOV, data complexity, FPA utilization, system complexity, coverage and cost of the different solutions. We will provide illustrations, calculations, and tradeoffs between three solutions evaluated by Opgal: A unique 3600 lens design using an LWIR XGA detector, stitching of three adjacent LWIR sensors equipped with a low distortion 1200 lens, and a fisheye lens with a HFOV of 180º and an XGA sensor.

An Exploration of WFC3/IR Dark Current Variation

NASA Astrophysics Data System (ADS)

Sunnquist, B.; Baggett, S.; Long, K. S.

2017-02-01

We use a collection of darks spanning September 2009 to June 2016 to study variations in the dark current in the IR detector on WFC3. Although the darks possess a similar signal pattern across the detector, we find that their median dark rates vary by as much as 0.014 DN/s (0.032 e-/s). The distribution of these median values has a triangular shape with a mean and standard deviation of 0.021 ± 0.0029 DN/s (0.049 ± 0.0069 e-/s). We observe a long term time-dependence in the inboard vertical reference pixel and zeroth read signals; however, these differences do not noticeably affect the calibrated dark signals, and we conclude that the WFC3/IR dark current levels continue to remain stable since launch. The inboard reference pixel signals exhibit a unique, but consistent, pattern around the detector, but this pattern does not evolve noticeably with the median of the science pixels, and a quadrant or row-based reference pixel subtraction strategy does not reduce the spread between the median dark rates. We notice a slight drift in the inboard reference pixel signals up the dark ramps, and the intensity of this drift is related to the median dark current in the science pixels. This holds true using either the horizontal or vertical reference pixels and for darks with a variety of sample sequences.

Reconstruction of 2D PET data with Monte Carlo generated system matrix for generalized natural pixels

NASA Astrophysics Data System (ADS)

Vandenberghe, Stefaan; Staelens, Steven; Byrne, Charles L.; Soares, Edward J.; Lemahieu, Ignace; Glick, Stephen J.

2006-06-01

In discrete detector PET, natural pixels are image basis functions calculated from the response of detector pairs. By using reconstruction with natural pixel basis functions, the discretization of the object into a predefined grid can be avoided. Here, we propose to use generalized natural pixel reconstruction. Using this approach, the basis functions are not the detector sensitivity functions as in the natural pixel case but uniform parallel strips. The backprojection of the strip coefficients results in the reconstructed image. This paper proposes an easy and efficient way to generate the matrix M directly by Monte Carlo simulation. Elements of the generalized natural pixel system matrix are formed by calculating the intersection of a parallel strip with the detector sensitivity function. These generalized natural pixels are easier to use than conventional natural pixels because the final step from solution to a square pixel representation is done by simple backprojection. Due to rotational symmetry in the PET scanner, the matrix M is block circulant and only the first blockrow needs to be stored. Data were generated using a fast Monte Carlo simulator using ray tracing. The proposed method was compared to a listmode MLEM algorithm, which used ray tracing for doing forward and backprojection. Comparison of the algorithms with different phantoms showed that an improved resolution can be obtained using generalized natural pixel reconstruction with accurate system modelling. In addition, it was noted that for the same resolution a lower noise level is present in this reconstruction. A numerical observer study showed the proposed method exhibited increased performance as compared to a standard listmode EM algorithm. In another study, more realistic data were generated using the GATE Monte Carlo simulator. For these data, a more uniform contrast recovery and a better contrast-to-noise performance were observed. It was observed that major improvements in contrast recovery were obtained with MLEM when the correct system matrix was used instead of simple ray tracing. The correct modelling was the major cause of improved contrast for the same background noise. Less important factors were the choice of the algorithm (MLEM performed better than ART) and the basis functions (generalized natural pixels gave better results than pixels).

Investigation of a Multi-Anode Microchannel Plate PMT for Time-of-Flight PET

NASA Astrophysics Data System (ADS)

Choong, Woon-Seng

2010-10-01

We report on an investigation of a mulit-anode microchannel plate PMT for time-of-flight PET detector modules. The primary advantages of an MCP lie in its excellent timing properties (fast rise time and low transit time spread), compact size, and reasonably large active area, thus making it a good candidate for TOF applications. In addition, the anode can be segmented into an array of collection electrodes with fine pitch to attain good position sensitivity. In this paper, we investigate using the Photonis Planacon MCP-PMT with a pore size of 10 μm to construct a PET detector module, specifically for time-of-flight applications. We measure the single electron response by exciting the Planacon with pulsed laser diode. We also measure the performance of the Planacon as a PET detector by coupling a 4 mm×4 mm×10 mm LSO crystal to individual pixel to study its gain uniformity, energy resolution, and timing resolution. The rise time of the Planacon is 440 ps with pulse duration of about 1 ns. A transit time spread of 120 ps FWHM is achieved. The gain is fairly uniform across the central region of the Planacon, but drops off by as much as a factor of 2.5 around the edges. The energy resolution is fairly uniform across the Planacon with an average value of 18.6 ± 0.7% FWHM. While the average timing resolution of 252 ± 7 ps FWHM is achieved in the central region of the Planacon, it degrades to 280 ± 9 ps FWHM for edge pixels and 316 ± 15 ps FWHM for corner pixels. We compare the results with measurements performed with a fast timing conventional PMT (Hamamatsu R-9800). We find that the R9800, which has significantly higher PDE, has a better timing resolution than the Planacon. Furthermore, we perform detector simulations to calculate the improvement that can be achieved with a higher PDE Planacon. The calculation shows that the Planacon can achieve significantly better timing resolution if it can attain the same PDE as the R-9800, while only a 30% improvement is needed to yield a similar timing resolution as the R-9800.

A MAPS Based Micro-Vertex Detector for the STAR Experiment

DOE PAGES

Schambach, Joachim; Anderssen, Eric; Contin, Giacomo; ...

2015-06-18

For the 2014 heavy ion run of RHIC a new micro-vertex detector called the Heavy Flavor Tracker (HFT) was installed in the STAR experiment. The HFT consists of three detector subsystems with various silicon technologies arranged in 4 approximately concentric cylinders close to the STAR interaction point designed to improve the STAR detector’s vertex resolution and extend its measurement capabilities in the heavy flavor domain. The two innermost HFT layers are placed at radii of 2.8 cm and 8 cm from the beam line. These layers are constructed with 400 high resolution sensors based on CMOS Monolithic Active Pixel Sensormore » (MAPS) technology arranged in 10-sensor ladders mounted on 10 thin carbon fiber sectors to cover a total silicon area of 0.16 m 2. Each sensor of this PiXeL (“PXL”) sub-detector combines a pixel array of 928 rows and 960 columns with a 20.7 μm pixel pitch together with front-end electronics and zero-suppression circuitry in one silicon die providing a sensitive area of ~3.8 cm 2. This sensor architecture features 185.6 μs readout time and 170 mW/cm 2 power dissipation. This low power dissipation allows the PXL detector to be air-cooled, and with the sensors thinned down to 50 μm results in a global material budget of only 0.4% radiation length per layer. A novel mechanical approach to detector insertion allows us to effectively install and integrate the PXL sub-detector within a 12 hour period during an on-going multi-month data taking period. The detector requirements, architecture and design, as well as the performance after installation, are presented in this paper.« less

Introducing a non-pixelated and fast centre of mass detector for differential phase contrast microscopy.

PubMed

Schwarzhuber, Felix; Melzl, Peter; Pöllath, Simon; Zweck, Josef

2018-06-10

With the advent of probe corrected STEM machines it became possible to probe specimens on a scale of less than 50 pm resolution. This opens completely new horizons for research, as it is e.g. possible to probe the electrostatic fields between individual rows of atoms, using differential phase contrast (DPC). However, in contrast to conventional DPC, where one deals with extended fields which can be assumed constant across the electron probe, this is not possible for sub-atomic probes in DPC. For the latter case it was shown [1,2], that the strongly inhomogeneous field distribution within the probe diameter, which usually is caused by the nuclear potentials of an atomic column, leads to a complicated intensity redistribution within the diffraction disk. The task is then to determine the intensity weighted centre of the diffraction disk pattern (frequently also called centre of mass, COM), which is proportional to the average lateral momentum gained by the average electron, transmitted through the probe diameter. In first reported measurements, the determination of this COM was achieved using a pixelated detector in combination with a software-based evaluation of the COM. This suffers from two disadvantages: first, the nowadays available pixelated detectors are still not very fast (approximately 1000 fps) and quite expensive, and second, the amount of data to be processed after acquisition is comparatively huge. In this paper we report on an alternative to a pixelated detector, which is able to directly deliver the COM of a diffraction disk's intensity distribution with frequencies up to 200 kHz. We present measurements on the sensitivity of this detector as well as first results from DPC imaging. From these results we expect the detector also to serve well in sub-atomic DPC field sensing, possibly replacing today's segmented or pixelated detectors. Copyright © 2018 Elsevier B.V. All rights reserved.

Centroid estimation for a Shack-Hartmann wavefront sensor based on stream processing.

PubMed

Kong, Fanpeng; Polo, Manuel Cegarra; Lambert, Andrew

2017-08-10

Using center of gravity to estimate the centroid of the spot in a Shack-Hartmann wavefront sensor, the measurement corrupts with photon and detector noise. Parameters, like window size, often require careful optimization to balance the noise error, dynamic range, and linearity of the response coefficient under different photon flux. It also needs to be substituted by the correlation method for extended sources. We propose a centroid estimator based on stream processing, where the center of gravity calculation window floats with the incoming pixel from the detector. In comparison with conventional methods, we show that the proposed estimator simplifies the choice of optimized parameters, provides a unit linear coefficient response, and reduces the influence of background and noise. It is shown that the stream-based centroid estimator also works well for limited size extended sources. A hardware implementation of the proposed estimator is discussed.

A feasibility study of X-ray phase-contrast mammographic tomography at the Imaging and Medical beamline of the Australian Synchrotron.

PubMed

Nesterets, Yakov I; Gureyev, Timur E; Mayo, Sheridan C; Stevenson, Andrew W; Thompson, Darren; Brown, Jeremy M C; Kitchen, Marcus J; Pavlov, Konstantin M; Lockie, Darren; Brun, Francesco; Tromba, Giuliana

2015-11-01

Results are presented of a recent experiment at the Imaging and Medical beamline of the Australian Synchrotron intended to contribute to the implementation of low-dose high-sensitivity three-dimensional mammographic phase-contrast imaging, initially at synchrotrons and subsequently in hospitals and medical imaging clinics. The effect of such imaging parameters as X-ray energy, source size, detector resolution, sample-to-detector distance, scanning and data processing strategies in the case of propagation-based phase-contrast computed tomography (CT) have been tested, quantified, evaluated and optimized using a plastic phantom simulating relevant breast-tissue characteristics. Analysis of the data collected using a Hamamatsu CMOS Flat Panel Sensor, with a pixel size of 100 µm, revealed the presence of propagation-based phase contrast and demonstrated significant improvement of the quality of phase-contrast CT imaging compared with conventional (absorption-based) CT, at medically acceptable radiation doses.

A superconducting focal plane array for ultraviolet, optical, and near-infrared astrophysics.

PubMed

Mazin, Benjamin A; Bumble, Bruce; Meeker, Seth R; O'Brien, Kieran; McHugh, Sean; Langman, Eric

2012-01-16

Microwave Kinetic Inductance Detectors, or MKIDs, have proven to be a powerful cryogenic detector technology due to their sensitivity and the ease with which they can be multiplexed into large arrays. A MKID is an energy sensor based on a photon-variable superconducting inductance in a lithographed microresonator, and is capable of functioning as a photon detector across the electromagnetic spectrum as well as a particle detector. Here we describe the first successful effort to create a photon-counting, energy-resolving ultraviolet, optical, and near infrared MKID focal plane array. These new Optical Lumped Element (OLE) MKID arrays have significant advantages over semiconductor detectors like charge coupled devices (CCDs). They can count individual photons with essentially no false counts and determine the energy and arrival time of every photon with good quantum efficiency. Their physical pixel size and maximum count rate is well matched with large telescopes. These capabilities enable powerful new astrophysical instruments usable from the ground and space. MKIDs could eventually supplant semiconductor detectors for most astronomical instrumentation, and will be useful for other disciplines such as quantum optics and biological imaging.

First results of a highly granulated 3D CdTe detector module for PET

NASA Astrophysics Data System (ADS)

Chmeissani, Mokhtar; Kolstein, Machiel; Macias-Montero, José Gabriel; Puigdengoles, Carles; García, Jorge; Prats, Xavier; Martínez, Ricardo

2018-01-01

We present the performance of a highly granulated 3D detector module for PET, consisting of a stack of pixelated CdTe detectors. Each detector module has 2 cm  ×  2 cm  ×  2 cm of CdTe material, subdivided into 4000 voxels, where each voxel has size 1 mm  ×  1 mm  ×  2 mm and is connected to its own read-out electronics via a BiSn solder ball. Each read-out channel consists of a preamp, a discriminator, a shaper, a peak-and-hold circuit and a 10 bits SAR ADC. The preamp has variable gain where at the maximum gain the ADC resolution is equivalent to 0.7 keV. Each ASIC chip reads 100 CdTe pixel channels and has one TDC to measure the time stamp of the triggered events, with a time resolution of less than 1 ns. With the bias voltage set at  -250 V mm-1 and for 17838 working channels out of a total of 20 000, we have obtained an average energy resolution of 2.2% FWHM for 511 keV photons. For 511 keV photons that have undergone Compton scattering, we measured an energy resolution of 3.2% FWHM. A timing resolution for PET coincidence events of 60 ns FWHM was found.

Design, optimization and evaluation of a "smart" pixel sensor array for low-dose digital radiography

NASA Astrophysics Data System (ADS)

Wang, Kai; Liu, Xinghui; Ou, Hai; Chen, Jun

2016-04-01

Amorphous silicon (a-Si:H) thin-film transistors (TFTs) have been widely used to build flat-panel X-ray detectors for digital radiography (DR). As the demand for low-dose X-ray imaging grows, a detector with high signal-to-noise-ratio (SNR) pixel architecture emerges. "Smart" pixel is intended to use a dual-gate photosensitive TFT for sensing, storage, and switch. It differs from a conventional passive pixel sensor (PPS) and active pixel sensor (APS) in that all these three functions are combined into one device instead of three separate units in a pixel. Thus, it is expected to have high fill factor and high spatial resolution. In addition, it utilizes the amplification effect of the dual-gate photosensitive TFT to form a one-transistor APS that leads to a potentially high SNR. This paper addresses the design, optimization and evaluation of the smart pixel sensor and array for low-dose DR. We will design and optimize the smart pixel from the scintillator to TFT levels and validate it through optical and electrical simulation and experiments of a 4x4 sensor array.

Superconducting Microwave Resonator Arrays for Submillimeter/Far-Infrared Imaging

NASA Astrophysics Data System (ADS)

Noroozian, Omid

Superconducting microwave resonators have the potential to revolutionize submillimeter and far-infrared astronomy, and with it our understanding of the universe. The field of low-temperature detector technology has reached a point where extremely sensitive devices like transition-edge sensors are now capable of detecting radiation limited by the background noise of the universe. However, the size of these detector arrays are limited to only a few thousand pixels. This is because of the cost and complexity of fabricating large-scale arrays of these detectors that can reach up to 10 lithographic levels on chip, and the complicated SQUID-based multiplexing circuitry and wiring for readout of each detector. In order to make substantial progress, next-generation ground-based telescopes such as CCAT or future space telescopes require focal planes with large-scale detector arrays of 104--10 6 pixels. Arrays using microwave kinetic inductance detectors (MKID) are a potential solution. These arrays can be easily made with a single layer of superconducting metal film deposited on a silicon substrate and pattered using conventional optical lithography. Furthermore, MKIDs are inherently multiplexable in the frequency domain, allowing ˜ 10 3 detectors to be read out using a single coaxial transmission line and cryogenic amplifier, drastically reducing cost and complexity. An MKID uses the change in the microwave surface impedance of a superconducting thin-film microresonator to detect photons. Absorption of photons in the superconductor breaks Cooper pairs into quasiparticles, changing the complex surface impedance, which results in a perturbation of resonator frequency and quality factor. For excitation and readout, the resonator is weakly coupled to a transmission line. The complex amplitude of a microwave probe signal tuned on-resonance and transmitted on the feedline past the resonator is perturbed as photons are absorbed in the superconductor. The perturbation can be detected using a cryogenic amplifier and subsequent homodyne mixing at room temperature. In an array of MKIDs, all the resonators are coupled to a shared feedline and are tuned to slightly different frequencies. They can be read out simultaneously using a comb of frequencies generated and measured using digital techniques. This thesis documents an effort to demonstrate the basic operation of ˜ 256 pixel arrays of lumped-element MKIDs made from superconducting TiN x on silicon. The resonators are designed and simulated for optimum operation. Various properties of the resonators and arrays are measured and compared to theoretical expectations. A particularly exciting observation is the extremely high quality factors (˜ 3 x 107) of our TiNx resonators which is essential for ultra-high sensitivity. The arrays are tightly packed both in space and in frequency which is desirable for larger full-size arrays. However, this can cause a serious problem in terms of microwave crosstalk between neighboring pixels. We show that by properly designing the resonator geometry, crosstalk can be eliminated; this is supported by our measurement results. We also tackle the problem of excess frequency noise in MKIDs. Intrinsic noise in the form of an excess resonance frequency jitter exists in planar superconducting resonators that are made on dielectric substrates. We conclusively show that this noise is due to fluctuations of the resonator capacitance. In turn, the capacitance fluctuations are thought to be driven by two-level system (TLS) fluctuators in a thin layer on the surface of the device. With a modified resonator design we demonstrate with measurements that this noise can be substantially reduced. An optimized version of this resonator was designed for the multiwavelength submillimeter kinetic inductance camera (MUSIC) instrument for the Caltech Submillimeter Observatory.

Homogeneity study of a GaAs:Cr pixelated sensor by means of X-rays

NASA Astrophysics Data System (ADS)

Billoud, T.; Leroy, C.; Papadatos, C.; Pichotka, M.; Pospisil, S.; Roux, J. S.

2018-04-01

Direct conversion semiconductor detectors have become an indispensable tool in radiation detection by now. In order to obtain a high detection efficiency, especially when detecting X or γ rays, high-Z semiconductor sensors are necessary. Like other compound semiconductors GaAs, compensated by chromium (GaAs:Cr), suffers from a number of defects that affect the charge collection efficiency and homogeneity of the material. A precise knowledge of this problem is important to predict the performance of such detectors and eventually correct their response in specific applications. In this study we analyse the homogeneity and mobility-lifetime products (μe τe) of a 500 μ m thick GaAs:Cr pixelated sensor connected to a Timepix chip. The detector is irradiated by 23 keV X-rays, each pixel recording the number of photon interactions and the charge they induce on its electrode. The μe τe products are extracted on a per-pixel basis, using the Hecht equation corrected for the small pixel effect. The detector shows a good time stability in the experimental conditions. Significant inhomogeneities are observed in photon counting and charge collection efficiencies. An average μe τe of 1.0 ṡ 10‑4 cm2V‑1 is found, and compared with values obtained by other methods for the same material. Solutions to improve the response are discussed.

An asynchronous data-driven readout prototype for CEPC vertex detector

NASA Astrophysics Data System (ADS)

Yang, Ping; Sun, Xiangming; Huang, Guangming; Xiao, Le; Gao, Chaosong; Huang, Xing; Zhou, Wei; Ren, Weiping; Li, Yashu; Liu, Jianchao; You, Bihui; Zhang, Li

2017-12-01

The Circular Electron Positron Collider (CEPC) is proposed as a Higgs boson and/or Z boson factory for high-precision measurements on the Higgs boson. The precision of secondary vertex impact parameter plays an important role in such measurements which typically rely on flavor-tagging. Thus silicon CMOS Pixel Sensors (CPS) are the most promising technology candidate for a CEPC vertex detector, which can most likely feature a high position resolution, a low power consumption and a fast readout simultaneously. For the R&D of the CEPC vertex detector, we have developed a prototype MIC4 in the Towerjazz 180 nm CMOS Image Sensor (CIS) process. We have proposed and implemented a new architecture of asynchronous zero-suppression data-driven readout inside the matrix combined with a binary front-end inside the pixel. The matrix contains 128 rows and 64 columns with a small pixel pitch of 25 μm. The readout architecture has implemented the traditional OR-gate chain inside a super pixel combined with a priority arbiter tree between the super pixels, only reading out relevant pixels. The MIC4 architecture will be introduced in more detail in this paper. It will be taped out in May and will be characterized when the chip comes back.

Development of monolithic pixel detector with SOI technology for the ILC vertex detector

NASA Astrophysics Data System (ADS)

Yamada, M.; Ono, S.; Tsuboyama, T.; Arai, Y.; Haba, J.; Ikegami, Y.; Kurachi, I.; Togawa, M.; Mori, T.; Aoyagi, W.; Endo, S.; Hara, K.; Honda, S.; Sekigawa, D.

2018-01-01

We have been developing a monolithic pixel sensor for the International Linear Collider (ILC) vertex detector with the 0.2 μm FD-SOI CMOS process by LAPIS Semiconductor Co., Ltd. We aim to achieve a 3 μm single-point resolution required for the ILC with a 20×20 μm2 pixel. Beam bunch crossing at the ILC occurs every 554 ns in 1-msec-long bunch trains with an interval of 200 ms. Each pixel must record the charge and time stamp of a hit to identify a collision bunch for event reconstruction. Necessary functions include the amplifier, comparator, shift register, analog memory and time stamp implementation in each pixel, and column ADC and Zero-suppression logic on the chip. We tested the first prototype sensor, SOFIST ver.1, with a 120 GeV proton beam at the Fermilab Test Beam Facility in January 2017. SOFIST ver.1 has a charge sensitive amplifier and two analog memories in each pixel, and an 8-bit Wilkinson-type ADC is implemented for each column on the chip. We measured the residual of the hit position to the reconstructed track. The standard deviation of the residual distribution fitted by a Gaussian is better than 3 μm.

LAMBDA 2M GaAs—A multi-megapixel hard X-ray detector for synchrotrons

NASA Astrophysics Data System (ADS)

Pennicard, D.; Smoljanin, S.; Pithan, F.; Sarajlic, M.; Rothkirch, A.; Yu, Y.; Liermann, H. P.; Morgenroth, W.; Winkler, B.; Jenei, Z.; Stawitz, H.; Becker, J.; Graafsma, H.

2018-01-01

Synchrotrons can provide very intense and focused X-ray beams, which can be used to study the structure of matter down to the atomic scale. In many experiments, the quality of the results depends strongly on detector performance; in particular, experiments studying dynamics of samples require fast, sensitive X-ray detectors. "LAMBDA" is a photon-counting hybrid pixel detector system for experiments at synchrotrons, based on the Medipix3 readout chip. Its main features are a combination of comparatively small pixel size (55 μm), high readout speed at up to 2000 frames per second with no time gap between images, a large tileable module design, and compatibility with high-Z sensors for efficient detection of higher X-ray energies. A large LAMBDA system for hard X-ray detection has been built using Cr-compensated GaAs as a sensor material. The system is composed of 6 GaAs tiles, each of 768 by 512 pixels, giving a system with approximately 2 megapixels and an area of 8.5 by 8.5 cm2. While the sensor uniformity of GaAs is not as high as that of silicon, its behaviour is stable over time, and it is possible to correct nonuniformities effectively by postprocessing of images. By using multiple 10 Gigabit Ethernet data links, the system can be read out at the full speed of 2000 frames per second. The system has been used in hard X-ray diffraction experiments studying the structure of samples under extreme pressure in diamond anvil cells. These experiments can provide insight into geological processes. Thanks to the combination of high speed readout, large area and high sensitivity to hard X-rays, it is possible to obtain previously unattainable information in these experiments about atomic-scale structure on a millisecond timescale during rapid changes of pressure or temperature.

WFC3 UVIS Detector Performance

NASA Astrophysics Data System (ADS)

Gunning, Heather C.; Baggett, Sylvia M.; Gosmeyer, Catherine; Bourque, Matthew; MacKenty, John W.; Anderson, Jay; WFC3 Team

2015-01-01

The Wide Field Camera 3 (WFC3) is a fourth-generation imaging instrument installed on the Hubble Space Telescope (HST) during Servicing Mission 4 (SM4) in May 2000. WFC3 has two observational channels, UV/visible (UVIS) and infrared (IR); both have been performing well on-orbit. Since installation, the WFC3 team has been diligent in monitoring the performance of both detectors. The UVIS channel consists of two e2v, backside illuminated, 2Kx4K CCDs arranged in a 2x1 mosaic. We present results from some of the monitoring programs used to check various aspects of the UVIS detector. We discuss the growth trend of hot pixels and the efficacy of regular anneals in controlling the hot pixel population. We detail a pixel population with lowered-sensitivity that evolves during the time between anneals, and is largely reset by each anneal procedure. We discuss the stability of the post-flash LED lamp, used and recommended for CTE mitigation in observations with less than 12 e-/pixel backgrounds. Finally, we summarize long-term photometric trends of the UVIS detector, as well as the absolute gain measurement, used as a proxy for the on-orbit evolution of the UVIS channel.

CMOS Active Pixel Sensors as energy-range detectors for proton Computed Tomography.

PubMed

Esposito, M; Anaxagoras, T; Evans, P M; Green, S; Manolopoulos, S; Nieto-Camero, J; Parker, D J; Poludniowski, G; Price, T; Waltham, C; Allinson, N M

2015-06-03

Since the first proof of concept in the early 70s, a number of technologies has been proposed to perform proton CT (pCT), as a means of mapping tissue stopping power for accurate treatment planning in proton therapy. Previous prototypes of energy-range detectors for pCT have been mainly based on the use of scintillator-based calorimeters, to measure proton residual energy after passing through the patient. However, such an approach is limited by the need for only a single proton passing through the energy-range detector in a read-out cycle. A novel approach to this problem could be the use of pixelated detectors, where the independent read-out of each pixel allows to measure simultaneously the residual energy of a number of protons in the same read-out cycle, facilitating a faster and more efficient pCT scan. This paper investigates the suitability of CMOS Active Pixel Sensors (APSs) to track individual protons as they go through a number of CMOS layers, forming an energy-range telescope. Measurements performed at the iThemba Laboratories will be presented and analysed in terms of correlation, to confirm capability of proton tracking for CMOS APSs.

A Pixel Readout Chip in 40 nm CMOS Process for High Count Rate Imaging Systems with Minimization of Charge Sharing Effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maj, Piotr; Grybos, P.; Szczgiel, R.

2013-11-07

We present a prototype chip in 40 nm CMOS technology for readout of hybrid pixel detector. The prototype chip has a matrix of 18x24 pixels with a pixel pitch of 100 μm. It can operate both in single photon counting (SPC) mode and in C8P1 mode. In SPC the measured ENC is 84 e ₋rms (for the peaking time of 48 ns), while the effective offset spread is below 2 mV rms. In the C8P1 mode the chip reconstructs full charge deposited in the detector, even in the case of charge sharing, and it identifies a pixel with the largestmore » charge deposition. The chip architecture and preliminary measurements are reported.« less

New CHOD detector for the NA62 experiment at CERN

NASA Astrophysics Data System (ADS)

Fedotov, S. A.; Kleymenova, A. A.; Khotjantsev, A. N.

2018-01-01

The New CHOD is a scintillation hodoscope with a pad structure featuring a total of 148 counters. The signal from each pad is read out using wavelength-shifting fibers and two or four SensL SiPMs with a sensitive area of 3 × 3 mm2. This photodetector has 4774 pixels 35 × 35 μm2 in size. The key parameters (photon detection efficiency, dark current, crosstalk, and gain) were measured for 500 SiPMs.

Using the Medipix3 detector for direct electron imaging in the range 60 keV to 200 keV in electron microscopy

NASA Astrophysics Data System (ADS)

Mir, J. A.; Plackett, R.; Shipsey, I.; dos Santos, J. M. F.

2017-11-01

Hybrid pixel sensor technology such as the Medipix3 represents a unique tool for electron imaging. We have investigated its performance as a direct imaging detector using a Transmission Electron Microscope (TEM) which incorporated a Medipix3 detector with a 300 μm thick silicon layer compromising of 256×256 pixels at 55 μm pixel pitch. We present results taken with the Medipix3 in Single Pixel Mode (SPM) with electron beam energies in the range, 60-200 keV . Measurements of the Modulation Transfer Function (MTF) and the Detective Quantum Efficiency (DQE) were investigated. At a given beam energy, the MTF data was acquired by deploying the established knife edge technique. Similarly, the experimental data required to determine DQE was obtained by acquiring a stack of images of a focused beam and of free space (flatfield) to determine the Noise Power Spectrum (NPS).

1024x1024 Pixel MWIR and LWIR QWIP Focal Plane Arrays and 320x256 MWIR:LWIR Pixel Colocated Simultaneous Dualband QWIP Focal Plane Arrays

NASA Technical Reports Server (NTRS)

Gunapala, Sarath D.; Bandara, Sumith V.; Liu, John K.; Hill, Cory J.; Rafol, S. B.; Mumolo, Jason M.; Trinh, Joseph T.; Tidrow, M. Z.; Le Van, P. D.

2005-01-01

Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024x1024 pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NE(Delta)T) of 17 mK at a 95K operating temperature with f/2.5 optics at 300K background and the LWIR detector array has demonstrated a NE(Delta)T of 13 mK at a 70K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90K and 70K operating-temperatures respectively, with similar optical and background conditions. In addition, we are in the process of developing MWIR and LWIR pixel collocated simultaneously readable dualband QWIP focal plane arrays.

Development of a circular shape Si-PM-based detector ring for breast-dedicated PET system

NASA Astrophysics Data System (ADS)

Nakanishi, Kouhei; Yamamoto, Seiichi; Watabe, Hiroshi; Abe, Shinji; Fujita, Naotoshi; Kato, Katsuhiko

2018-02-01

In clinical situations, various breast-dedicated positron emission tomography (PET) systems have been used. However, clinical breast-dedicated PET systems have polygonal detector ring. Polygonal detector ring sometimes causes image artifact, so complicated reconstruction algorithm is needed to reduce artifact. Consequently, we developed a circular detector ring for breast-dedicated PET to obtain images without artifact using a simple reconstruction algorithm. We used Lu1.9Gd0.1SiO5 (LGSO) scintillator block which was made of 1.5 x 1.9 x 15 mm pixels that were arranged in an 8 x 24 matrix. As photodetectors, we used silicon photomultiplier (Si-PM) arrays whose channel size was 3 x 3 mm. A detector unit was composed of four scintillator blocks, 16 Si-PM arrays and a light guide. The developed detector unit had angled configuration since the light guide was bending. A detector unit had three gaps with an angle of 5.625° between scintillator blocks. With these configurations, we could arrange 64 scintillator blocks in nearly circular shape (regular 64-sided polygon) using 16 detector units. The use of the smaller number of detector units could reduce the size of the front-end electronics circuits. The inner diameter of the developed detector ring was 260 mm. This size was similar to those of brain PET systems, so our breast-dedicated PET detector ring can measure not only breast but also brain. Measured radial, tangential and axial spatial resolution of the detector ring reconstructed by the filtered back-projection (FBP) algorithm were 2.1 mm FWHM, 2.0 mm FWHM and 1.7 mm FWHM at center of field of view (FOV), respectively. The sensitivity was 2.0% at center of the axial FOV. With the developed detector ring, we could obtain high resolution image of the breast phantom and the brain phantom. We conclude that our developed Si-PM-based detector ring is promising for a high resolution breast-dedicated PET system that can also be used for brain PET system.

Tests of UFXC32k chip with CdTe pixel detector

NASA Astrophysics Data System (ADS)

Maj, P.; Taguchi, T.; Nakaye, Y.

2018-02-01

The paper presents the performance of the UFXC32K—a hybrid pixel detector readout chip working with CdTe detectors. The UFXC32K has a pixel pitch of 75 μm and can cope with both input signal polarities. This functionality allows operating with widely used silicon sensors collecting holes and CdTe sensors collecting electrons. This article describes the chip focusing on solving the issues connected to high-Z sensor material, namely high leakage currents, slow charge collection time and thick material resulting in increased charge-sharring effects. The measurements were conducted with higher X-ray energies including 17.4 keV from molybdenum. Conclusions drawn inside the paper show the UFXC32K's usability for CdTe sensors in high X-ray energy applications.

Utilisation de dispositifs a transfert de charge pour la detection de muons cosmiques dans un contexte de tomographie

NASA Astrophysics Data System (ADS)

Marion-Ouellet, Laurence Olivier

Faced with the threat of nuclear terrorism, many countries have purchased radioactive material detectors to protect their borders. These systems usually detect gamma, beta or alpha ray emissions coming from uranium, radium, cesium or other radioactive material. However, the radioactive source can be concealed by thick lead shielding and radiation absorbing material. With enough shielding, an individual wishing to smuggle illicit nuclear material could cross borders without alerting the authorities. To address this risk, several laboratories worldwide are working on muon tomography technology. This technique aims to detect shielded nuclear material by measuring the deflection of a cosmic muon after crossing the cargo of interest. Since this deviation is a function of the Z number of atoms (the number of protons inside the nucleus), it is possible to determine the contents of the cargo. To calculate the angular deviation, we must first measure the position of the muon on four succeding horizontal planes (two pre-cargo, two after). This task is traditionally assigned to wire chambers or scintillators detectors but could also be fulfilled by CCD detectors (Charge-Coupled Devices). This work specifically addresses the use of CCDs for muon tomography. This thesis' objective is to determine the feasibility of using a commercial CCD based muon detector. To answer this question, numerical simulations have been performed using the software Geant4. This work allows us to obtain the theoretical energy deposition of muons of various kinetic energies into a silicon wafer representing a CCD chip. These results are then compared to numerical values derived from the theory presented in the literature to verify their validity. The muons' energy is varied from 50 MeV to 1 TeV and silicium thicknesses of 300 and 775 mum are studied. The results obtained indicate that a muon of 4 GeV (most probable cosmic muon energy) should deposit 106 and 281 keV for an average thickness of 300 and 775 mum respectively, which translates to 28 000 and 76 000 electron-hole pairs as signal for the two thicknesses. All the results obtained through Geant4 are consistent with the known theory of energy deposits in thin semiconductor materials. A practical experimentation was also considered, using an astronomical camera DMK51 AU02.AS to capture a series of images hidden from light with the camera turned towards the sky. The pixels presenting a high intensity are considered to be the consequence of the passage of a muon. The expected rate of detection according to the size of the detector was 0.372 muons per minute but the results were 0.1578 muons per minute for data taken inside Polytechnique and 0.1615 for images taken outside. Therefore, the presence of about two meters of concrete above the camera does not significantly affect the detectable muon flux. However, the ratio of 40 % between expected signal and the observations is explained by the small size of the sensitive area of a pixel when compared to its total size. Components such as electrodes and differently doped silicon occupy a certain area in the pixel causing it, in the eyes of the muon, to be much smaller. A smaller pixel will ensure a smaller expected muon flux. Also, the possibility that the energy deposition is simply too small in some cases to be detected is also studied in the results section and solutions to resolve this problem are presented in the conclusion.

SPIDR, a general-purpose readout system for pixel ASICs

NASA Astrophysics Data System (ADS)

van der Heijden, B.; Visser, J.; van Beuzekom, M.; Boterenbrood, H.; Kulis, S.; Munneke, B.; Schreuder, F.

2017-02-01

The SPIDR (Speedy PIxel Detector Readout) system is a flexible general-purpose readout platform that can be easily adapted to test and characterize new and existing detector readout ASICs. It is originally designed for the readout of pixel ASICs from the Medipix/Timepix family, but other types of ASICs or front-end circuits can be read out as well. The SPIDR system consists of an FPGA board with memory and various communication interfaces, FPGA firmware, CPU subsystem and an API library on the PC . The FPGA firmware can be adapted to read out other ASICs by re-using IP blocks. The available IP blocks include a UDP packet builder, 1 and 10 Gigabit Ethernet MAC's and a "soft core" CPU . Currently the firmware is targeted at the Xilinx VC707 development board and at a custom board called Compact-SPIDR . The firmware can easily be ported to other Xilinx 7 series and ultra scale FPGAs. The gap between an ASIC and the data acquisition back-end is bridged by the SPIDR system. Using the high pin count VITA 57 FPGA Mezzanine Card (FMC) connector only a simple chip carrier PCB is required. A 1 and a 10 Gigabit Ethernet interface handle the connection to the back-end. These can be used simultaneously for high-speed data and configuration over separate channels. In addition to the FMC connector, configurable inputs and outputs are available for synchronization with other detectors. A high resolution (≈ 27 ps bin size) Time to Digital converter is provided for time stamping events in the detector. The SPIDR system is frequently used as readout for the Medipix3 and Timepix3 ASICs. Using the 10 Gigabit Ethernet interface it is possible to read out a single chip at full bandwidth or up to 12 chips at a reduced rate. Another recent application is the test-bed for the VeloPix ASIC, which is developed for the Vertex Detector of the LHCb experiment. In this case the SPIDR system processes the 20 Gbps scrambled data stream from the VeloPix and distributes it over four 10 Gigabit Ethernet links, and in addition provides the slow and fast control for the chip.

An ultra-low power self-timed column-level ADC for a CMOS pixel sensor based vertex detector

NASA Astrophysics Data System (ADS)

Zhang, L.; Wang, M.

2014-11-01

The International Large Detector (ILD) is a detector concept for the future linear collider experiment. The vertex detector is the key tool to achieve high precision measurements for flavor tagging, which puts stringent requirements on the CMOS pixel sensors. Due to the cooling systems which deteriorate the material budget and increase the multiple scattering, it is important to reduce the power consumption. This paper presents an ultra-low power self-timed column-level ADC for the CMOS pixel sensors, aiming to equip the outer layers of the vertex detector. The ADC was designed to operate in two modes (active and idle) adapted to the low hit density in the outer layers. The architecture employs an enhanced sample-and-hold circuit and a self-timed technique. The total power consumption with a 3-V supply is 225μW during idle mode, which is the most frequent situation. This value rises to 425μW in the case of the active mode. It occupies an area of 35 × 590μm2.

Characterization of an in-vacuum PILATUS 1M detector.

PubMed

Wernecke, Jan; Gollwitzer, Christian; Müller, Peter; Krumrey, Michael

2014-05-01

A dedicated in-vacuum X-ray detector based on the hybrid pixel PILATUS 1M detector has been installed at the four-crystal monochromator beamline of the PTB at the electron storage ring BESSY II in Berlin, Germany. Owing to its windowless operation, the detector can be used in the entire photon energy range of the beamline from 10 keV down to 1.75 keV for small-angle X-ray scattering (SAXS) experiments and anomalous SAXS at absorption edges of light elements. The radiometric and geometric properties of the detector such as quantum efficiency, pixel pitch and module alignment have been determined with low uncertainties. The first grazing-incidence SAXS results demonstrate the superior resolution in momentum transfer achievable at low photon energies.

dada - a web-based 2D detector analysis tool

NASA Astrophysics Data System (ADS)

Osterhoff, Markus

2017-06-01

The data daemon, dada, is a server backend for unified access to 2D pixel detector image data stored with different detectors, file formats and saved with varying naming conventions and folder structures across instruments. Furthermore, dada implements basic pre-processing and analysis routines from pixel binning over azimuthal integration to raster scan processing. Common user interactions with dada are by a web frontend, but all parameters for an analysis are encoded into a Uniform Resource Identifier (URI) which can also be written by hand or scripts for batch processing.

High speed systems for time-resolved experiments with synchrotron radiation

NASA Astrophysics Data System (ADS)

Koziol, Anna; Maj, Piotr

2018-02-01

The UFXC32k is a single photon counting hybrid pixel detector with 75 μm pixel pitch. It was designed to cope with high X-ray intensities and therefore it is a very good candiate for synchrotron applications. In order to use this detector in an application, a dedicated setup must be designed and built allowing proper operation of the detector within the experiment. The paper presents two setups built for the purpose of Pump-Probe-Probe experiments at the Synchrotron SOLEIL and XPCS experiments at the APS.

Note: A disposable x-ray camera based on mass produced complementary metal-oxide-semiconductor sensors and single-board computers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoidn, Oliver R.; Seidler, Gerald T., E-mail: seidler@uw.edu

We have integrated mass-produced commercial complementary metal-oxide-semiconductor (CMOS) image sensors and off-the-shelf single-board computers into an x-ray camera platform optimized for acquisition of x-ray spectra and radiographs at energies of 2–6 keV. The CMOS sensor and single-board computer are complemented by custom mounting and interface hardware that can be easily acquired from rapid prototyping services. For single-pixel detection events, i.e., events where the deposited energy from one photon is substantially localized in a single pixel, we establish ∼20% quantum efficiency at 2.6 keV with ∼190 eV resolution and a 100 kHz maximum detection rate. The detector platform’s useful intrinsic energymore » resolution, 5-μm pixel size, ease of use, and obvious potential for parallelization make it a promising candidate for many applications at synchrotron facilities, in laser-heating plasma physics studies, and in laboratory-based x-ray spectrometry.« less

Mercuric iodide room-temperature array detectors for gamma-ray imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patt, B.

Significant progress has been made recently in the development of mercuric iodide detector arrays for gamma-ray imaging, making real the possibility of constructing high-performance small, light-weight, portable gamma-ray imaging systems. New techniques have been applied in detector fabrication and then low noise electronics which have produced pixel arrays with high-energy resolution, high spatial resolution, high gamma stopping efficiency. Measurements of the energy resolution capability have been made on a 19-element protypical array. Pixel energy resolutions of 2.98% fwhm and 3.88% fwhm were obtained at 59 keV (241-Am) and 140-keV (99m-Tc), respectively. The pixel spectra for a 14-element section of themore » data is shown together with the composition of the overlapped individual pixel spectra. These techniques are now being applied to fabricate much larger arrays with thousands of pixels. Extension of these principles to imaging scenarios involving gamma-ray energies up to several hundred keV is also possible. This would enable imaging of the 208 keV and 375-414 keV 239-Pu and 240-Pu structures, as well as the 186 keV line of 235-U.« less

A 128 x 128 InGaAs detector array for 1.0 - 1.7 microns

NASA Technical Reports Server (NTRS)

Olsen, G.; Joshi, A.; Lange, M.; Woodruff, K.; Mykietyn, E.; Gay, D.; Ackley, D.; Erickson, G.; Ban, V.; Staller, C.

1990-01-01

A two-dimensional 128 x 128 detector array for the 1.0 - 1.7 micron spectral region has been demonstrated with indium gallium arsenide. The 30 micron square pixels had 60 micron spacing in both directions and were designed to be compatible with a 2D Reticon multiplexer. Dark currents below 100 pA, capacitance near 0.1 pF, and quantum efficiencies above 80 percent were measured. Probe maps of dark current and quantum efficiency are presented along with pixel dropout data and wafer yield which was as high as 99.89 percent (7 dropouts) in an area of 6528 pixels and 99.37 percent (103 dropouts) over an entire 128 x 128 pixel region.

New Optimizations of Microcalorimeter Arrays for High-Resolution Imaging X-ray Spectroscopy

NASA Astrophysics Data System (ADS)

Kilbourne, Caroline

We propose to continue our successful research program in developing arrays of superconducting transition-edge sensors (TES) for x-ray astrophysics. Our standard 0.3 mm TES pixel achieves better than 2.5-eV resolution, and we now make 32x32 arrays of such pixels. We have also achieved better than 1-eV resolution in smaller pixels, and promising performance in a range of position-sensitive designs. We propose to continue to advance the designs of both the single-pixel and position-sensitive microcalorimeters so that we can produce arrays suitable for several x-ray spectroscopy observatories presently in formulation. We will also investigate various array and pixel optimizations such as would be needed for large arrays for surveys, large- pixel arrays for diffuse soft x-ray measurements, or sub-arrays of fast pixels optimized for neutron-star burst spectroscopy. In addition, we will develop fabrication processes for integrating sub-arrays with very different pixel designs into a monolithic focal-plane array to simplify the design of the focal-plane assembly and make feasible new detector configurations such as the one currently baselined for AXSIO. Through a series of measurements on test devices, we have improved our understanding of the weak-link physics governing the observed resistive transitions in TES detectors. We propose to build on that work and ultimately use the results to improve the immunity of the detector to environmental magnetic fields, as well as its fundamental performance, in each of the targeted optimizations we are developing.

High-dynamic-range coherent diffractive imaging: ptychography using the mixed-mode pixel array detector.

PubMed

Giewekemeyer, Klaus; Philipp, Hugh T; Wilke, Robin N; Aquila, Andrew; Osterhoff, Markus; Tate, Mark W; Shanks, Katherine S; Zozulya, Alexey V; Salditt, Tim; Gruner, Sol M; Mancuso, Adrian P

2014-09-01

Coherent (X-ray) diffractive imaging (CDI) is an increasingly popular form of X-ray microscopy, mainly due to its potential to produce high-resolution images and the lack of an objective lens between the sample and its corresponding imaging detector. One challenge, however, is that very high dynamic range diffraction data must be collected to produce both quantitative and high-resolution images. In this work, hard X-ray ptychographic coherent diffractive imaging has been performed at the P10 beamline of the PETRA III synchrotron to demonstrate the potential of a very wide dynamic range imaging X-ray detector (the Mixed-Mode Pixel Array Detector, or MM-PAD). The detector is capable of single photon detection, detecting fluxes exceeding 1 × 10(8) 8-keV photons pixel(-1) s(-1), and framing at 1 kHz. A ptychographic reconstruction was performed using a peak focal intensity on the order of 1 × 10(10) photons µm(-2) s(-1) within an area of approximately 325 nm × 603 nm. This was done without need of a beam stop and with a very modest attenuation, while `still' images of the empty beam far-field intensity were recorded without any attenuation. The treatment of the detector frames and CDI methodology for reconstruction of non-sensitive detector regions, partially also extending the active detector area, are described.

DHS Internship Paper

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dreyer, J

2007-09-18

During my internship at Lawrence Livermore National Laboratory I worked with microcalorimeter gamma-ray and fast-neutron detectors based on superconducting Transition Edge Sensors (TESs). These instruments are being developed for fundamental science and nuclear non-proliferation applications because of their extremely high energy resolution; however, this comes at the expense of a small pixel size and slow decay times. The small pixel sizes are being addressed by developing detector arrays while the low count rate is being addressed by developing Digital Signal Processors (DSPs) that allow higher throughput than traditional pulse processing algorithms. Traditionally, low-temperature microcalorimeter pulses have been processed off-line withmore » optimum filtering routines based on the measured spectral characteristics of the signal and the noise. These optimum filters rely on the spectral content of the signal being identical for all events, and therefore require capturing the entire pulse signal without pile-up. In contrast, the DSP algorithm being developed is based on differences in signal levels before and after a trigger event, and therefore does not require the waveform to fully decay, or even the signal level to be close to the base line. The readout system allows for real time data acquisition and analysis at count rates exceeding 100 Hz for pulses with several {approx}ms decay times with minimal loss of energy resolution. Originally developed for gamma-ray analysis with HPGe detectors we have modified the hardware and firmware of the system to accommodate the slower TES signals and optimized the parameters of the filtering algorithm to maximize either resolution or throughput. The following presents an overview of the digital signal processing hardware and discusses the results of characterization measurements made to determine the systems performance.« less

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

PubMed

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.

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

NASA Astrophysics Data System (ADS)

Cho, H.-M.; Ding, H.; Ziemer, BP; Molloi, S.

2014-12-01

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 mm2 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.

Energy response calibration of photon-counting detectors using X-ray fluorescence: a feasibility study

PubMed Central

Cho, H-M; Ding, H; Ziemer, BP; Molloi, S

2014-01-01

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 mm2 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. PMID:25369288

Imaging performance of an amorphous selenium digital mammography detector in a breast tomosynthesis system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao Bo; Zhao Wei

2008-05-15

In breast tomosynthesis a rapid sequence of N images is acquired when the x-ray tube sweeps through different angular views with respect to the breast. Since the total dose to the breast is kept the same as that in regular mammography, the exposure used for each image of tomosynthesis is 1/N. The low dose and high frame rate pose a tremendous challenge to the imaging performance of digital mammography detectors. The purpose of the present work is to investigate the detector performance in different operational modes designed for tomosynthesis acquisition, e.g., binning or full resolution readout, the range of viewmore » angles, and the number of views N. A prototype breast tomosynthesis system with a nominal angular range of {+-}25 deg. was used in our investigation. The system was equipped with an amorphous selenium (a-Se) full field digital mammography detector with pixel size of 85 {mu}m. The detector can be read out in full resolution or 2x1 binning (binning in the tube travel direction). The focal spot blur due to continuous tube travel was measured for different acquisition geometries, and it was found that pixel binning, instead of focal spot blur, dominates the detector modulation transfer function (MTF). The noise power spectrum (NPS) and detective quantum efficiency (DQE) of the detector were measured with the exposure range of 0.4-6 mR, which is relevant to the low dose used in tomosynthesis. It was found that DQE at 0.4 mR is only 20% less than that at highest exposure for both detector readout modes. The detector temporal performance was categorized as lag and ghosting, both of which were measured as a function of x-ray exposure. The first frame lags were 8% and 4%, respectively, for binning and full resolution mode. Ghosting is negligible and independent of the frame rate. The results showed that the detector performance is x-ray quantum noise limited at the low exposures used in each view of tomosynthesis, and the temporal performance at high frame rate (up to 2 frames per second) is adequate for tomosynthesis.« less

Mini Compton Camera Based on an Array of Virtual Frisch-Grid CdZnTe Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Wonho; Bolotnikov, Aleksey; Lee, Taewoong

In this study, we constructed a mini Compton camera based on an array of CdZnTe detectors and assessed its spectral and imaging properties. The entire array consisted of 6×6 Frisch-grid CdZnTe detectors, each with a size of 6×6 ×15 mm 3. Since it is easier and more practical to grow small CdZnTe crystals rather than large monolithic ones, constructing a mosaic array of parallelepiped crystals can be an effective way to build a more efficient, large-volume detector. With the fully operational CdZnTe array, we measured the energy spectra for 133Ba -, 137Cs -, 60Co-radiation sources; we also located these sourcesmore » using a Compton imaging approach. Although the Compton camera was small enough to hand-carry, its intrinsic efficiency was several orders higher than those generated in previous researches using spatially separated arrays, because our camera measured the interactions inside the CZT detector array, wherein the detector elements were positioned very close to each other. Lastly, the performance of our camera was compared with that based on a pixelated detector.« less

Mini Compton Camera Based on an Array of Virtual Frisch-Grid CdZnTe Detectors

DOE PAGES

Lee, Wonho; Bolotnikov, Aleksey; Lee, Taewoong; ...

2016-02-15

In this study, we constructed a mini Compton camera based on an array of CdZnTe detectors and assessed its spectral and imaging properties. The entire array consisted of 6×6 Frisch-grid CdZnTe detectors, each with a size of 6×6 ×15 mm 3. Since it is easier and more practical to grow small CdZnTe crystals rather than large monolithic ones, constructing a mosaic array of parallelepiped crystals can be an effective way to build a more efficient, large-volume detector. With the fully operational CdZnTe array, we measured the energy spectra for 133Ba -, 137Cs -, 60Co-radiation sources; we also located these sourcesmore » using a Compton imaging approach. Although the Compton camera was small enough to hand-carry, its intrinsic efficiency was several orders higher than those generated in previous researches using spatially separated arrays, because our camera measured the interactions inside the CZT detector array, wherein the detector elements were positioned very close to each other. Lastly, the performance of our camera was compared with that based on a pixelated detector.« less

Landsat-Swath Imaging Spectrometer Design

NASA Technical Reports Server (NTRS)

Mouroulis, Pantazis; Green, Robert O.; Van Gorp, Byron; Moore, Lori; Wilson, Daniel W.; Bender, Holly A.

2015-01-01

We describe the design of a high-throughput pushbroom imaging spectrometer and telescope system that is capable of Landsat swath and resolution while providing better than 10 nm per pixel spectral resolution. The design is based on a 3200 x 480 element x 18 µm pixel size focal plane array, two of which are utilized to cover the full swath. At an optical speed of F/1.8, the system is the fastest proposed to date to our knowledge. The utilization of only two spectrometer modules fed from the same telescope reduces system complexity while providing a solution within achievable detector technology. Predictions of complete system response are shown. Also, it is shown that detailed ghost analysis is a requirement for this type of spectrometer and forms an essential part of a complete design.

Plasma-panel based detectors

NASA Astrophysics Data System (ADS)

Friedman, Peter

2017-09-01

The plasma panel sensor (PPS) is a novel micropattern gas detector inspired by plasma display panels (PDPs), the core component of plasma-TVs. A PDP comprises millions of discrete cells per square meter, each of which, when provided with a signal pulse, can initiate and sustain a plasma discharge. Configured as a detector, a pixel or cell is biased to discharge when a free-electron is generated in the gas. The PPS consists of an array of small plasma discharge pixels, and can be configured to have either an ``open-cell'' or ``closed-cell'' structure, operating with high gain in the Geiger region. We describe both configurations and their application to particle physics. The open-cell PPS lends itself to ultra-low-mass, ultrathin structures, whereas the closed-cell microhexcavity PPS is capable of higher performance. For the ultrathin-PPS, we are fabricating 3-inch devices based on two types of extremely thin, inorganic, transparent, substrate materials: one being 8-10 µm thick, and the other 25-27 µm thick. These gas-filled ultrathin devices are designed to operate in a beam-line vacuum environment, yet must be hermetically-sealed and gas-filled in an ambient environment at atmospheric pressure. We have successfully fabricated high resolution, submillimeter pixel electrodes on both types of ultrathin substrates. We will also report on the fabrication, staging and operation of the first microhexcavity detectors (µH-PPS). The first µH-PPS prototype devices have a 16 by 16 matrix of closed packed hexagon pixels, each having a 2 mm width. Initial tests of these detectors, conducted with Ne based gases at atmospheric pressure, indicate that each pixel responds independent of its neighboring cells, producing volt level pulse amplitudes in response to ionizing radiation. Results will include the hit rate response to a radioactive beta source, cosmic ray muons, the background from spontaneous discharge, pixel isolation and uniformity, and efficiency measurements. This work was funded in part by a DOE Office of Nuclear Physics SBIR Phase-II Grant.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fahim, Farah; Deptuch, Grzegorz W.; Hoff, James R.

Semiconductor hybrid pixel detectors often consist of a pixellated sensor layer bump bonded to a matching pixelated readout integrated circuit (ROIC). The sensor can range from high resistivity Si to III-V materials, whereas a Si CMOS process is typically used to manufacture the ROIC. Independent, device physics and electronic design automation (EDA) tools are used to determine sensor characteristics and verify functional performance of ROICs respectively with significantly different solvers. Some physics solvers provide the capability of transferring data to the EDA tool. However, single pixel transient simulations are either not feasible due to convergence difficulties or are prohibitively long.more » A simplified sensor model, which includes a current pulse in parallel with detector equivalent capacitor, is often used; even then, spice type top-level (entire array) simulations range from days to weeks. In order to analyze detector deficiencies for a particular scientific application, accurately defined transient behavioral models of all the functional blocks are required. Furthermore, various simulations, such as transient, noise, Monte Carlo, inter-pixel effects, etc. of the entire array need to be performed within a reasonable time frame without trading off accuracy. The sensor and the analog front-end can be modeling using a real number modeling language, as complex mathematical functions or detailed data can be saved to text files, for further top-level digital simulations. Parasitically aware digital timing is extracted in a standard delay format (sdf) from the pixel digital back-end layout as well as the periphery of the ROIC. For any given input, detector level worst-case and best-case simulations are performed using a Verilog simulation environment to determine the output. Each top-level transient simulation takes no more than 10-15 minutes. The impact of changing key parameters such as sensor Poissonian shot noise, analog front-end bandwidth, jitter due to clock distribution etc. can be accurately analyzed to determine ROIC architectural viability and bottlenecks. Hence the impact of the detector parameters on the scientific application can be studied.« less

Development of a long wave infrared detector for SGLI instrument

NASA Astrophysics Data System (ADS)

Dariel, Aurélien; Chorier, P.; Reeb, N.; Terrier, B.; Vuillermet, M.; Tribolet, P.

2007-10-01

The Japanese Aerospace Exploration Agency (JAXA) will be conducting the Global Change Observation Mission (GCOM) for monitoring of global environmental change. SGLI (Second Generation Global Imager) is an optical sensor on board GCOM-C (Climate), that includes a Long Wave IR Detector (LWIRD) sensitive up to about 13 μm. SGLI will provide high accuracy measurements of the atmosphere (aerosol, cloud ...), the cryosphere (glaciers, snow, sea ice ...), the biomass and the Earth temperature (sea and land). Sofradir is a major supplier of Space industry based on the use of a Space qualified MCT technology for detectors from 0.8 to 15 μm. This mature and reproducible technology has been used for 15 years to produce thousands of LWIR detectors with cut-off wavelengths between 9 and 12 μm. NEC Toshiba Space, prime contractor for the Second Generation Global Imager (SGLI), has selected SOFRADIR for its heritage in space projects and Mercury Cadmium Telluride (MCT) detectors to develop the LWIR detector. This detector includes two detection circuits for detection at 10.8 μm and 12.0 μm, hybridized on a single CMOS readout circuit. Each detection circuit is made of 20x2 square pixels of 140 μm. In order to optimize the overall performance, each pixel is made of 5x5 square sub-pixels of 28 μm and the readout circuit enables sub-pixel deselection. The MCT material and the photovoltaic technology are adapted to maximize response for the requested bandwidths: cut-off wavelengths of the 2 detection circuits are 12.6 and 13.4 μm at 55K. This detector is packaged into a sealed housing for full integration into a Dewar at 55K. This paper describes the main technical requirements, the design features of this detector, including trade-offs regarding performance optimization, and presents preliminary electro-optical results.

Simulation study of light transport in laser-processed LYSO:Ce detectors with single-side readout

NASA Astrophysics Data System (ADS)

Bläckberg, L.; El Fakhri, G.; Sabet, H.

2017-11-01

A tightly focused pulsed laser beam can locally modify the crystal structure inside the bulk of a scintillator. The result is incorporation of so-called optical barriers with a refractive index different from that of the crystal bulk, that can be used to redirect the scintillation light and control the light spread in the detector. We here systematically study the scintillation light transport in detectors fabricated using the laser induced optical barrier technique, and objectively compare their potential performance characteristics with those of the two mainstream detector types: monolithic and mechanically pixelated arrays. Among countless optical barrier patterns, we explore barriers arranged in a pixel-like pattern extending all-the-way or half-way through a 20 mm thick LYSO:Ce crystal. We analyze the performance of the detectors coupled to MPPC arrays, in terms of light response functions, flood maps, line profiles, and light collection efficiency. Our results show that laser-processed detectors with both barrier patterns constitute a new detector category with a behavior between that of the two standard detector types. Results show that when the barrier-crystal interface is smooth, no DOI information can be obtained regardless of barrier refractive index (RI). However, with a rough barrier-crystal interface we can extract multiple levels of DOI. Lower barrier RI results in larger light confinement, leading to better transverse resolution. Furthermore we see that the laser-processed crystals have the potential to increase the light collection efficiency, which could lead to improved energy resolution and potentially better timing resolution due to higher signals. For a laser-processed detector with smooth barrier-crystal interfaces the light collection efficiency is simulated to  >42%, and for rough interfaces  >73%. The corresponding numbers for a monolithic crystal is 39% with polished surfaces, and 71% with rough surfaces, and for a mechanically pixelated array 35% with polished pixel surfaces and 59% with rough surfaces.

Simulation study of light transport in laser-processed LYSO:Ce detectors with single-side readout.

PubMed

Bläckberg, L; El Fakhri, G; Sabet, H

2017-10-19

A tightly focused pulsed laser beam can locally modify the crystal structure inside the bulk of a scintillator. The result is incorporation of so-called optical barriers with a refractive index different from that of the crystal bulk, that can be used to redirect the scintillation light and control the light spread in the detector. We here systematically study the scintillation light transport in detectors fabricated using the laser induced optical barrier technique, and objectively compare their potential performance characteristics with those of the two mainstream detector types: monolithic and mechanically pixelated arrays. Among countless optical barrier patterns, we explore barriers arranged in a pixel-like pattern extending all-the-way or half-way through a 20 mm thick LYSO:Ce crystal. We analyze the performance of the detectors coupled to MPPC arrays, in terms of light response functions, flood maps, line profiles, and light collection efficiency. Our results show that laser-processed detectors with both barrier patterns constitute a new detector category with a behavior between that of the two standard detector types. Results show that when the barrier-crystal interface is smooth, no DOI information can be obtained regardless of barrier refractive index (RI). However, with a rough barrier-crystal interface we can extract multiple levels of DOI. Lower barrier RI results in larger light confinement, leading to better transverse resolution. Furthermore we see that the laser-processed crystals have the potential to increase the light collection efficiency, which could lead to improved energy resolution and potentially better timing resolution due to higher signals. For a laser-processed detector with smooth barrier-crystal interfaces the light collection efficiency is simulated to  >42%, and for rough interfaces  >73%. The corresponding numbers for a monolithic crystal is 39% with polished surfaces, and 71% with rough surfaces, and for a mechanically pixelated array 35% with polished pixel surfaces and 59% with rough surfaces.

X-ray Hybrid CMOS Detectors : Recent progress in development and characterization

NASA Astrophysics Data System (ADS)

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.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shanks, Katherine S.; Philipp, Hugh T.; Weiss, Joel T.

Experiments at storage ring light sources as well as at next-generation light sources increasingly require detectors capable of high dynamic range operation, combining low-noise detection of single photons with large pixel well depth. XFEL sources in particular provide pulse intensities sufficiently high that a purely photon-counting approach is impractical. The High Dynamic Range Pixel Array Detector (HDR-PAD) project aims to provide a dynamic range extending from single-photon sensitivity to 10{sup 6} photons/pixel in a single XFEL pulse while maintaining the ability to tolerate a sustained flux of 10{sup 11} ph/s/pixel at a storage ring source. Achieving these goals involves themore » development of fast pixel front-end electronics as well as, in the XFEL case, leveraging the delayed charge collection due to plasma effects in the sensor. A first prototype of essential electronic components of the HDR-PAD readout ASIC, exploring different options for the pixel front-end, has been fabricated. Here, the HDR-PAD concept and preliminary design will be described.« less

Delay Line Detectors for the UVCS and Sumer Instruments on the SOHO Satellite

NASA Technical Reports Server (NTRS)

Seigmund, O. H. W.; Stock, J. M.; Marsh, D. R.; Gummin, M. A.; Raffanti, R.; Hull, J.; Gaines, G. A.; Welsh, B.; Donakowski, B.; Jelinsky, P.;

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schambach, Joachim; Anderssen, Eric; Contin, Giacomo

For the 2014 heavy ion run of RHIC a new micro-vertex detector called the Heavy Flavor Tracker (HFT) was installed in the STAR experiment. The HFT consists of three detector subsystems with various silicon technologies arranged in 4 approximately concentric cylinders close to the STAR interaction point designed to improve the STAR detector’s vertex resolution and extend its measurement capabilities in the heavy flavor domain. The two innermost HFT layers are placed at radii of 2.8 cm and 8 cm from the beam line. These layers are constructed with 400 high resolution sensors based on CMOS Monolithic Active Pixel Sensormore » (MAPS) technology arranged in 10-sensor ladders mounted on 10 thin carbon fiber sectors to cover a total silicon area of 0.16 m 2. Each sensor of this PiXeL (“PXL”) sub-detector combines a pixel array of 928 rows and 960 columns with a 20.7 μm pixel pitch together with front-end electronics and zero-suppression circuitry in one silicon die providing a sensitive area of ~3.8 cm 2. This sensor architecture features 185.6 μs readout time and 170 mW/cm 2 power dissipation. This low power dissipation allows the PXL detector to be air-cooled, and with the sensors thinned down to 50 μm results in a global material budget of only 0.4% radiation length per layer. A novel mechanical approach to detector insertion allows us to effectively install and integrate the PXL sub-detector within a 12 hour period during an on-going multi-month data taking period. The detector requirements, architecture and design, as well as the performance after installation, are presented in this paper.« less

Analog pixel array detectors.

PubMed

Ercan, A; Tate, M W; Gruner, S M

2006-03-01

X-ray pixel array detectors (PADs) are generally thought of as either digital photon counters (DPADs) or X-ray analog-integrating pixel array detectors (APADs). Experiences with APADs, which are especially well suited for X-ray imaging experiments where transient or high instantaneous flux events must be recorded, are reported. The design, characterization and experimental applications of several APAD designs developed at Cornell University are discussed. The simplest design is a ;flash' architecture, wherein successive integrated X-ray images, as short as several hundred nanoseconds in duration, are stored in the detector chips for later off-chip digitization. Radiography experiments using a prototype flash APAD are summarized. Another design has been implemented that combines flash capability with the ability to continuously stream X-ray images at slower (e.g. milliseconds) rates. Progress is described towards radiation-hardened APADs that can be tiled to cover a large area. A mixed-mode PAD, design by combining many of the attractive features of both APADs and DPADs, is also described.

Life test of the InGaAs focal plane arrays detector for space applications

NASA Astrophysics Data System (ADS)

Zhu, Xian-Liang; Zhang, Hai-Yan; Li, Xue; Huang, Zhang-Cheng; Gong, Hai-Mei

2017-08-01

The short-wavelength infrared (SWIR) InGaAs focal plane array (FPA) detector consists of infrared detector chip, readout integrated circuit (ROIC), and flip-chip bonding interconnection by Indium bump. In order to satisfy space application requirements for failure rates or Mean Time to Failure (MTTF), which can only be demonstrated with the large number of detectors manufactured, the single pixel in InGaAs FPAs was chosen as the research object in this paper. The constant-stress accelerated life tests were carried out at 70°C 80°C 90°C and100°C. The failed pixels increased gradually during more than 14000 hours at each elevated temperatures. From the random failure data the activation energy was estimated to be 0.46eV, and the average lifetime of a single pixel in InGaAs FPAs was estimated to be longer than 1E+7h at the practical operating temperature (5°C).

High-contrast X-ray micro-tomography of low attenuation samples using large area hybrid semiconductor pixel detector array of 10 × 5 Timepix chips

NASA Astrophysics Data System (ADS)

Karch, J.; Krejci, F.; Bartl, B.; Dudak, J.; Kuba, J.; Kvacek, J.; Zemlicka, J.

2016-01-01

State-of-the-art hybrid pixel semiconductor detectors provide excellent imaging properties such as unlimited dynamic range, high spatial resolution, high frame rate and energy sensitivity. Nevertheless, a limitation in the use of these devices for imaging has been the small sensitive area of a few square centimetres. In the field of microtomography we make use of a large area pixel detector assembled from 50 Timepix edgeless chips providing fully sensitive area of 14.3 × 7.15 cm2. We have successfully demonstrated that the enlargement of the sensitive area enables high-quality tomographic measurements of whole objects with high geometrical magnification without any significant degradation in resulting reconstructions related to the chip tilling and edgeless sensor technology properties. The technique of micro-tomography with the newly developed large area detector is applied for samples formed by low attenuation, low contrast materials such a seed from Phacelia tanacetifolia, a charcoalified wood sample and a beeswax seal sample.

Calibration of the Auger Fluorescence Telescopes

NASA Astrophysics Data System (ADS)

Klages, H.; Pierre Auger Observatory Collaboration

Thirty fluorescence telescopes in four stations will overlook the detector array of the southern hemisphere experiment of the Pierre Auger project. The main aim of these telescopes is tracking of EHE air showers, measurement of the longitudinal shower development (Xmax) and determination of the absolute energy of EHE events. A telescope camera contains 440 PMTs each covering a 1.5 x 1.5 degree pixel of the sky. The response of every pixel is converted into the number of charged particles at the observed part of the shower. This reconstruction includes the shower/observer geometry and the details of the atmospheric photon production and transport. The remaining experimental task is to convert the ADC counts of the camera pixel electronics into the light flux entering the Schmidt aperture. Three types of calibration and control are necessary : a) Monitoring of time dependent variations has to be performed for all parts of the optics and for all pixels frequently. Common illumination for all pixels of a camera allows the detection of individual deviations. Properties of windows, filters and mirrors have to be measured separately. b) Differences in pixel-to-pixel efficiency are mainly due to PMT gain and to differences in effective area (camera shadow, mirror size limits). Homogeneous and isotropic illumination will enable cross calibration. c) An absolute calibration has to be performed once in a while using trusted light monitors. The calibration methods used for the Pierre Auger FD telescopes in Argentina are discussed.

A new imaging method for understanding chemical dynamics: efficient slice imaging using an in-vacuum pixel detector.

PubMed

Jungmann, J H; Gijsbertsen, A; Visser, J; Visschers, J; Heeren, R M A; Vrakking, M J J

2010-10-01

The implementation of the Timepix complementary metal oxide semiconductor pixel detector in velocity map slice imaging is presented. This new detector approach eliminates the need for gating the imaging detector. In time-of-flight mode, the detector returns the impact position and the time-of-flight of charged particles with 12.5 ns resolution and a dynamic range of about 100 μs. The implementation of the Timepix detector in combination with a microchannel plate additionally allows for high spatial resolution information via center-of-mass centroiding. Here, the detector was applied to study the photodissociation of NO(2) at 452 nm. The energy resolution observed in the experiment was ΔE/E=0.05 and is limited by the experimental setup rather than by the detector assembly. All together, this new compact detector assembly is well-suited for slice imaging and is a promising tool for imaging studies in atomic and molecular physics research.

Observation and analysis of microcirculation using high-spatial-resolution image detectors and synchrotron radiation

NASA Astrophysics Data System (ADS)

Umetani, Keiji; Yagi, Naoto; Suzuki, Yoshio; Ogasawara, Yasuo; Kajiya, Fumihiko; Matsumoto, Takeshi; Tachibana, Hiroyuki; Goto, Masami; Yamashita, Takenori; Imai, Shigeki; Kajihara, Yasumasa

2000-04-01

A microangiography system using monochromatized synchrotron radiation has been investigated as a diagnostic tool for circulatory disorders and early stage malignant tumors. The monochromatized X-rays with energies just above the contrast agent K-absorption edge energy can produce the highest contrast image of the contrast agent in small blood vessels. At SPring-8, digital microradiography with 6 - 24 micrometer pixel sizes has been carried out using two types of detectors designed for X-ray indirect and direct detection. The indirect-sensing detectors are fluorescent-screen optical-lens coupling systems using a high-sensitivity pickup-tube camera and a CCD camera. An X-ray image on the fluorescent screen is focused on the photoconductive layer of the pickup tube and the photosensitive area of the CCD by a small F number lens. The direct-sensing detector consists of an X-ray direct- sensing pickup tube with a beryllium faceplate for X-ray incidence to the photoconductive layer. Absorbed X-rays in the photoconductive layer are directly converted to photoelectrons and then signal charges are readout by electron beam scanning. The direct-sensing detector was expected to have higher spatial resolution in comparison with the indict-sensing detectors. Performance of the X-ray image detectors was examined at the bending magnet beamline BL20B2 using monochromatized X-ray at SPring-8. Image signals from the camera are converted into digital format by an analog-to- digital converter and stored in a frame memory with image format of 1024 X 1024 pixels. In preliminary experiments, tumor vessel specimens using barium contrast agent were prepared for taking static images. The growth pattern of tumor-induced vessels was clearly visualized. Heart muscle specimens were prepared for imaging of 3-dimensional microtomography using the fluorescent-screen CCD camera system. The complex structure of small blood vessels with diameters of 30 - 40 micrometer was visualized as a 3- dimensional CT image.

RVS large format arrays for astronomy

NASA Astrophysics Data System (ADS)

Starr, Barry; Mears, Lynn; Fulk, Chad; Getty, Jonathan; Beuville, Eric; Boe, Raymond; Tracy, Christopher; Corrales, Elizabeth; Kilcoyne, Sean; Vampola, John; Drab, John; Peralta, Richard; Doyle, Christy

2016-07-01

Raytheon Vision Systems (RVS) has a long history of providing state of the art infrared sensor chip assemblies (SCAs) for the astronomical community. This paper will provide an update of RVS capabilities for the community not only for the infrared wavelengths but also in the visible wavelengths as well. Large format infrared detector arrays are now available that meet the demanding requirements of the low background scientific community across the wavelength spectrum. These detector arrays have formats from 1k x 1k to as large as 8k x 8k with pixel sizes ranging from 8 to 27 μm. Focal plane arrays have been demonstrated with a variety of detector materials: SiPiN, HgCdTe, InSb, and Si:As IBC. All of these detector materials have demonstrated low noise and dark current, high quantum efficiency, and excellent uniformity. All can meet the high performance requirements for low-background within the limits of their respective spectral and operating temperature ranges.

Characterization of Silicon Photomultiplier Detectors using Cosmic Radiation

NASA Astrophysics Data System (ADS)

Zavala, Favian; Castro, Juan; Niduaza, Rexavalmar; Wedel, Zachary; Fan, Sewan; Ritt, Stefan; Fatuzzo, Laura

2014-03-01

The silicon photomultiplier light detector has gained a lot of attention lately in fields such as particle physics, astrophysics, and medical physics. Its popularity stems from its lower cost, compact size, insensitivity to magnetic fields, and its excellent ability to distinguish a quantized number of photons. They are normally operated at room temperature and biased above their breakdown voltages. As such, they may also exhibit properties that may hinder their optimal operation which include a thermally induced high dark count rate, after pulse effects, and cross talk from photons in nearby pixels. At this poster session, we describe our data analysis and our endeavor to characterize the multipixel photon counter (MPPC) detectors from Hamamatsu under different bias voltages and temperature conditions. Particularly, we describe our setup which uses cosmic rays to induce scintillation light delivered to the detector by wavelength shifting optical fibers and the use of a fast 1 GHz waveform sampler, the domino ring sampler (DRS4) digitizer board. Department of Education grant number P031S90007.

Shadow-free single-pixel imaging

NASA Astrophysics Data System (ADS)

Li, Shunhua; Zhang, Zibang; Ma, Xiao; Zhong, Jingang

2017-11-01

Single-pixel imaging is an innovative imaging scheme and receives increasing attention in recent years, for it is applicable for imaging at non-visible wavelengths and imaging under weak light conditions. However, as in conventional imaging, shadows would likely occur in single-pixel imaging and sometimes bring negative effects in practical uses. In this paper, the principle of shadows occurrence in single-pixel imaging is analyzed, following which a technique for shadows removal is proposed. In the proposed technique, several single-pixel detectors are used to detect the backscattered light at different locations so that the shadows in the reconstructed images corresponding to each detector shadows are complementary. Shadow-free reconstruction can be derived by fusing the shadow-complementary images using maximum selection rule. To deal with the problem of intensity mismatch in image fusion, we put forward a simple calibration. As experimentally demonstrated, the technique is able to reconstruct monochromatic and full-color shadow-free images.

Apparatus And Method For Osl-Based, Remote Radiation Monitoring And Spectrometry

DOEpatents

Miller, Steven D.; Smith, Leon Eric; Skorpik, James R.

2006-03-07

Compact, OSL-based devices for long-term, unattended radiation detection and spectroscopy are provided. In addition, a method for extracting spectroscopic information from these devices is taught. The devices can comprise OSL pixels and at least one radiation filter surrounding at least a portion of the OSL pixels. The filter can modulate an incident radiation flux. The devices can further comprise a light source and a detector, both proximally located to the OSL pixels, as well as a power source and a wireless communication device, each operably connected to the light source and the detector. Power consumption of the device ranges from ultra-low to zero. The OSL pixels can retain data regarding incident radiation events as trapped charges. The data can be extracted wirelessly or manually. The method for extracting spectroscopic data comprises optically stimulating the exposed OSL pixels, detecting a readout luminescence, and reconstructing an incident-energy spectrum from the luminescence.

Apparatus and method for OSL-based, remote radiation monitoring and spectrometry

DOEpatents

Smith, Leon Eric [Richland, WA; Miller, Steven D [Richland, WA; Bowyer, Theodore W [Oakton, VA

2008-05-20

Compact, OSL-based devices for long-term, unattended radiation detection and spectroscopy are provided. In addition, a method for extracting spectroscopic information from these devices is taught. The devices can comprise OSL pixels and at least one radiation filter surrounding at least a portion of the OSL pixels. The filter can modulate an incident radiation flux. The devices can further comprise a light source and a detector, both proximally located to the OSL pixels, as well as a power source and a wireless communication device, each operably connected to the light source and the detector. Power consumption of the device ranges from ultra-low to zero. The OSL pixels can retain data regarding incident radiation events as trapped charges. The data can be extracted wirelessly or manually. The method for extracting spectroscopic data comprises optically stimulating the exposed OSL pixels, detecting a readout luminescence, and reconstructing an incident-energy spectrum from the luminescence.

Characterisation results of the CMOS VISNIR spectral band detector for the METimage instrument

NASA Astrophysics Data System (ADS)

Pratlong, Jérôme; Schmuelling, Frank; Benitez, Victor; Breart De Boisanger, Michel; Skegg, Michael; Simpson, Robert; Bowring, Steve; Krzizok, Natalie

2017-09-01

The METimage instrument is part of the EPS-SG (EUMETSAT Polar System Second Generation) program. It will be situated on the MetOp-SG platform which in operation has an objective of collecting data for meteorology and climate monitoring as well as their forecasting. Teledyne e2v has developed and characterised the CMOS VISNIR detector flight module part of the METimage instrument. This paper will focus on the silicon results obtained from the CMOS VISNIR detector flight model. The detector is a large multi-linear device composed of 7 spectral bands covering a wavelength range from 428 nm to 923 nm (some bands are placed twice and added together to enhance the signal-to-noise performance). This detector uses a 4T pixel, with a size of 250μm square, presenting challenges to achieve good charge transfer efficiency with high conversion factor and good linearity for signal levels up to 2M electrons and with high line rates. Low noise has been achieved using correlated double sampling to suppress the read-out noise and give a maximum dynamic range that is significantly larger than in standard commercial devices. The photodiode occupies a significant fraction of the large pixel area. This makes it possible to meet the detection efficiency when front illuminated. A thicker than standard epitaxial silicon is used to improve NIR response. However, the dielectric stack on top of the sensor produces Fabry-Perot étalon effects, which are problematic for narrow band illumination as this causes the detection efficiency to vary significantly over a small wavelength range. In order to reduce this effect and to meet the specification, the silicon manufacturing process has been modified. The flight model will have black coating deposited between each spectral channel, onto the active silicon regions.

New amorphous-silicon image sensor for x-ray diagnostic medical imaging applications

NASA Astrophysics Data System (ADS)

Weisfield, Richard L.; Hartney, Mark A.; Street, Robert A.; Apte, Raj B.

1998-07-01

This paper introduces new high-resolution amorphous Silicon (a-Si) image sensors specifically configured for demonstrating film-quality medical x-ray imaging capabilities. The devices utilizes an x-ray phosphor screen coupled to an array of a-Si photodiodes for detecting visible light, and a-Si thin-film transistors (TFTs) for connecting the photodiodes to external readout electronics. We have developed imagers based on a pixel size of 127 micrometer X 127 micrometer with an approximately page-size imaging area of 244 mm X 195 mm, and array size of 1,536 data lines by 1,920 gate lines, for a total of 2.95 million pixels. More recently, we have developed a much larger imager based on the same pixel pattern, which covers an area of approximately 406 mm X 293 mm, with 2,304 data lines by 3,200 gate lines, for a total of nearly 7.4 million pixels. This is very likely to be the largest image sensor array and highest pixel count detector fabricated on a single substrate. Both imagers connect to a standard PC and are capable of taking an image in a few seconds. Through design rule optimization we have achieved a light sensitive area of 57% and optimized quantum efficiency for x-ray phosphor output in the green part of the spectrum, yielding an average quantum efficiency between 500 and 600 nm of approximately 70%. At the same time, we have managed to reduce extraneous leakage currents on these devices to a few fA per pixel, which allows for very high dynamic range to be achieved. We have characterized leakage currents as a function of photodiode bias, time and temperature to demonstrate high stability over these large sized arrays. At the electronics level, we have adopted a new generation of low noise, charge- sensitive amplifiers coupled to 12-bit A/D converters. Considerable attention was given to reducing electronic noise in order to demonstrate a large dynamic range (over 4,000:1) for medical imaging applications. Through a combination of low data lines capacitance, readout amplifier design, optimized timing, and noise cancellation techniques, we achieve 1,000e to 2,000e of noise for the page size and large size arrays, respectively. This allows for true 12-bit performance and quantum limited images over a wide range of x-ray exposures. Various approaches to reducing line correlated noise have been implemented and will be discussed. Images documenting the improved performance will be presented. Avenues for improvement are under development, including higher resolution 97 micrometer pixel imagers, further improvements in detective quantum efficiency, and characterization of dynamic behavior.

Fast, High-Precision Readout Circuit for Detector Arrays

NASA Technical Reports Server (NTRS)

Rider, David M.; Hancock, Bruce R.; Key, Richard W.; Cunningham, Thomas J.; Wrigley, Chris J.; Seshadri, Suresh; Sander, Stanley P.; Blavier, Jean-Francois L.

2013-01-01

The GEO-CAPE mission described in NASA's Earth Science and Applications Decadal Survey requires high spatial, temporal, and spectral resolution measurements to monitor and characterize the rapidly changing chemistry of the troposphere over North and South Americas. High-frame-rate focal plane arrays (FPAs) with many pixels are needed to enable such measurements. A high-throughput digital detector readout integrated circuit (ROIC) that meets the GEO-CAPE FPA needs has been developed, fabricated, and tested. The ROIC is based on an innovative charge integrating, fast, high-precision analog-to-digital circuit that is built into each pixel. The 128×128-pixel ROIC digitizes all 16,384 pixels simultaneously at frame rates up to 16 kHz to provide a completely digital output on a single integrated circuit at an unprecedented rate of 262 million pixels per second. The approach eliminates the need for off focal plane electronics, greatly reducing volume, mass, and power compared to conventional FPA implementations. A focal plane based on this ROIC will require less than 2 W of power on a 1×1-cm integrated circuit. The ROIC is fabricated of silicon using CMOS technology. It is designed to be indium bump bonded to a variety of detector materials including silicon PIN diodes, indium antimonide (InSb), indium gallium arsenide (In- GaAs), and mercury cadmium telluride (HgCdTe) detector arrays to provide coverage over a broad spectral range in the infrared, visible, and ultraviolet spectral ranges.

Investigating the effect of pixel size of high spatial resolution FTIR imaging for detection of colorectal cancer

NASA Astrophysics Data System (ADS)

Lloyd, G. R.; Nallala, J.; Stone, N.

2016-03-01

FTIR is a well-established technique and there is significant interest in applying this technique to medical diagnostics e.g. to detect cancer. The introduction of focal plane array (FPA) detectors means that FTIR is particularly suited to rapid imaging of biopsy sections as an adjunct to digital pathology. Until recently however each pixel in the image has been limited to a minimum of 5.5 µm which results in a comparatively low magnification image or histology applications and potentially the loss of important diagnostic information. The recent introduction of higher magnification optics gives image pixels that cover approx. 1.1 µm. This reduction in image pixel size gives images of higher magnification and improved spatial detail can be observed. However, the effect of increasing the magnification on spectral quality and the ability to discriminate between disease states is not well studied. In this work we test the discriminatory performance of FTIR imaging using both standard (5.5 µm) and high (1.1 µm) magnification for the detection of colorectal cancer and explore the effect of binning to degrade high resolution images to determine whether similar diagnostic information and performance can be obtained using both magnifications. Results indicate that diagnostic performance using high magnification may be reduced as compared to standard magnification when using existing multivariate approaches. Reduction of the high magnification data to standard magnification via binning can potentially recover some of the lost performance.

Design and characterization of novel monolithic pixel sensors for the ALICE ITS upgrade

NASA Astrophysics Data System (ADS)

Cavicchioli, C.; Chalmet, P. L.; Giubilato, P.; Hillemanns, H.; Junique, A.; Kugathasan, T.; Mager, M.; Marin Tobon, C. A.; Martinengo, P.; Mattiazzo, S.; Mugnier, H.; Musa, L.; Pantano, D.; Rousset, J.; Reidt, F.; Riedler, P.; Snoeys, W.; Van Hoorne, J. W.; Yang, P.

2014-11-01

Within the R&D activities for the upgrade of the ALICE Inner Tracking System (ITS), Monolithic Active Pixel Sensors (MAPS) are being developed and studied, due to their lower material budget ( 0.3 %X0 in total for each inner layer) and higher granularity ( 20 μm × 20 μm pixels) with respect to the present pixel detector. This paper presents the design and characterization results of the Explorer0 chip, manufactured in the TowerJazz 180 nm CMOS Imaging Sensor process, based on a wafer with high-resistivity (ρ > 1 kΩ cm) and 18 μm thick epitaxial layer. The chip is organized in two sub-matrices with different pixel pitches (20 μm and 30 μm), each of them containing several pixel designs. The collection electrode size and shape, as well as the distance between the electrode and the surrounding electronics, are varied; the chip also offers the possibility to decouple the charge integration time from the readout time, and to change the sensor bias. The charge collection properties of the different pixel variants implemented in Explorer0 have been studied using a 55Fe X-ray source and 1-5 GeV/c electrons and positrons. The sensor capacitance has been estimated, and the effect of the sensor bias has also been examined in detail. A second version of the Explorer0 chip (called Explorer1) has been submitted for production in March 2013, together with a novel circuit with in-pixel discrimination and a sparsified readout. Results from these submissions are also presented.