WorldWideScience

Sample records for borne x-ray detectors

  1. X-ray detector

    International Nuclear Information System (INIS)

    The multicell X-ray or gamma detector is used in computer tomography. To achieve good spatial resolution, the electrode plates are narrowly spaced in each cell and are designed identical over the whole length of the detector group. The uniform spacing and precise check of the angles between the electrodes and accurate control of the dimensions of the whole detector structure are achieved by depositing, in the fabrication process, a viscous, resin type material (e.g., epoxy resin) or glue at selected points between the electrodes and insulators. (ORU)

  2. Pyroelectric x-ray detectors and x-ray pyrometers

    International Nuclear Information System (INIS)

    This paper discusses pyroelectric detectors which are very promising x-ray detectors for intense pulsed x-ray/γ-ray measurements and can be used as x-ray pyrometers. They are fast, passive, and inherently flat in spectral response for low energy x-rays. The authors report tests of LiTaO3, Sr.5Ba.5Nb2O6 and LiNbO3 detectors at Nova laser with 1 ns low energy x-rays and at Zapp Z-pinch machine with 100 ns x-rays. The temporal and spectral responses are discussed

  3. Pyroelectric x-ray detectors and x-ray pyrometers

    International Nuclear Information System (INIS)

    Pyroelectric detectors are very promising x-ray detectors for intense pulsed x-ray/γ-ray measurements and can be used as x-ray pyrometers. They are fast, passive, and inherently flat in spectral response for low-energy x rays. We report our tests of LiTaO3 detectors at Nova laser with 1-ns low-energy x rays and at Zapp Z-pinch machine with 100-ns x rays. The temporal and spectral responses are discussed

  4. Semiconductor X-ray detectors

    CERN Document Server

    Lowe, Barrie Glyn

    2014-01-01

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

  5. Multicell X-ray detector

    International Nuclear Information System (INIS)

    A detector for X-radiation or other ionizing radiation is described comprising a pair of curved metal bars lying in spaced apart parallel planes. Ceramic members are bonded to the respective bars in facing relationship. Each ceramic member has a plurality of radially extending circumferentially spaced grooves facing similar grooves in the other member. A plurality of electrode plates are held in juxtaposed and circumferentially spaced apart relationship by disposing their respective upper and lower edges in the grooves of opposed ceramic members. The faces of adjacent electrode plates define gas-filled gaps in which photoelectron-ion pairs are produced when radiation enters from the front edges of the plates. The above described assembly is disposed within a pressurized gas-filled chamber having an X-ray transmissive window adjacent the front edges of the plates. A cover encloses the chamber. It has insulator feed-throughs for connecting the electrode plates with external electric circuits. Photoelectrons and/or ions, created by the ionizing radiation, are collected on the electrode plates and thereby generate an electrical signal which corresponds to the incident ionizing radiation. (Auth.)

  6. X-Ray Detector Simulations - Oral Presentation

    International Nuclear Information System (INIS)

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

  7. X-Ray Detector Simulations - Oral Presentation

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-20

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

  8. Advanced detectors for X-ray microscopy

    International Nuclear Information System (INIS)

    Over the last decade the advances in x-ray microscopy have mainly been due to the development of x-ray source technology and to the micro-fabrication of x-ray optics. These advances have spurred the development of x-ray microscopes that are approaching the best resolution possible in the presence of radiation damage in the specimen. In addition, the development of specimen preparation techniques that reduce tile effects of radiation damage on the specimen are underway. In contrast, tile development or x-ray detectors for x-ray microscopy has been a low priority. The objective of the work was to develop a new detector for x-ray microscopy. This involved the modification of a Thorn EMI electron tube in order to sensitise the multiplier for soil x-rays In the energy range of interest (0.2-6 keV). The electron multiplier was then tested on a repetitive laser plasma source, which has been shown to be eminently suitable for a laboratory scale x-ray microscope, and the Scanning Transmission X-ray Microscope (STXM) at the National Synchrotron Light Source (NSLS), which is the most successful STXM presently in operation. The processed data from tile electron multiplier was used to characterise its response and assess its potential as all alternative to existing detectors. In addition, ID21, the microscopy beamline at the European Synchrotron Radiation Source (ESRF) was studied to assess the need for a beam position monitor close to the exit slit of the monochromator. This involved the ray tracing of the beamline. It was proposed that in the case of a crystal monochromator a beam position monitor based oil the total signal from a photo-emitting blade containing a number of different diameter pinholes was sufficient. However, for a grating monochromator tile beamline design relied upon feedback from a beam position monitor capable of detecting the height of the beam at tile entrance to the microscope. A number of conceptual designs for a monitor that could fulfil this

  9. TV X-ray flaw detector

    International Nuclear Information System (INIS)

    The aim of the invention is to ensure optimum operation of a TV x-ray flaw detector under transient non-destructive testing conditions. The operating conditions are optimized by using an electronic circuit compromizing series-connected line block extraction block, peak detector, differentiation block, zero member and control unit of radiation source voltage supply. The block diagram of the flaw detector is given, its operation principle is described

  10. Neutron and X-ray Detectors

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-01

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

  11. X-ray detectors in medical imaging

    International Nuclear Information System (INIS)

    Healthcare systems are subject to continuous adaptation, following trends such as the change of demographic structures, the rise of life-style related and chronic diseases, and the need for efficient and outcome-oriented procedures. This also influences the design of new imaging systems as well as their components. The applications of X-ray imaging in the medical field are manifold and have led to dedicated modalities supporting specific imaging requirements, for example in computed tomography (CT), radiography, angiography, surgery or mammography, delivering projection or volumetric imaging data. Depending on the clinical needs, some X-ray systems enable diagnostic imaging while others support interventional procedures. X-ray detector design requirements for the different medical applications can vary strongly with respect to size and shape, spatial resolution, frame rates and X-ray flux, among others. Today, integrating X-ray detectors are in common use. They are predominantly based on scintillators (e.g. CsI or Gd2O2S) and arrays of photodiodes made from crystalline silicon (Si) or amorphous silicon (a-Si) or they employ semiconductors (e.g. Se) with active a-Si readout matrices. Ongoing and future developments of X-ray detectors will include optimization of current state-of-the-art integrating detectors in terms of performance and cost, will enable the usage of large size CMOS-based detectors, and may facilitate photon counting techniques with the potential to further enhance performance characteristics and foster the prospect of new clinical applications

  12. X-ray detectors in medical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Spahn, Martin, E-mail: martin.spahn@siemens.com [Siemens AG, Healthcare Sector, Imaging and Therapy Systems, 91301 Forchheim (Germany)

    2013-12-11

    Healthcare systems are subject to continuous adaptation, following trends such as the change of demographic structures, the rise of life-style related and chronic diseases, and the need for efficient and outcome-oriented procedures. This also influences the design of new imaging systems as well as their components. The applications of X-ray imaging in the medical field are manifold and have led to dedicated modalities supporting specific imaging requirements, for example in computed tomography (CT), radiography, angiography, surgery or mammography, delivering projection or volumetric imaging data. Depending on the clinical needs, some X-ray systems enable diagnostic imaging while others support interventional procedures. X-ray detector design requirements for the different medical applications can vary strongly with respect to size and shape, spatial resolution, frame rates and X-ray flux, among others. Today, integrating X-ray detectors are in common use. They are predominantly based on scintillators (e.g. CsI or Gd{sub 2}O{sub 2}S) and arrays of photodiodes made from crystalline silicon (Si) or amorphous silicon (a-Si) or they employ semiconductors (e.g. Se) with active a-Si readout matrices. Ongoing and future developments of X-ray detectors will include optimization of current state-of-the-art integrating detectors in terms of performance and cost, will enable the usage of large size CMOS-based detectors, and may facilitate photon counting techniques with the potential to further enhance performance characteristics and foster the prospect of new clinical applications.

  13. Position sensitive x-ray detector

    International Nuclear Information System (INIS)

    A multi ware position sensitive gas counter for X-ray detection was developed in our laboratory, making use of commercial delay-lines for position sensing. Six delay-line chips (50 ns delay each, 40 Mhz cut-off frequency) cover a total sensitive length of 150 mm leading to a delay-risetime ratio that allows for a high-resolution position detection. Tests using the 5,9 keV X-ray line from a 55 Fe source and integral linearity better than 0,1% and a maximal differential linearity of ±4,0% were obtained operating the detector with an Ar-C H4 (90%-10%) gas mixture at 700 torr. Similar tests were performed, using the 8,04 keV line from a Cu x-ray tube. A total resolution of 330 μm, and the same integral and differential linearities were obtained. (author)

  14. Silicon lithium detector for x ray fluorescence

    International Nuclear Information System (INIS)

    The Silicon Lithium detector is the system for the detection of nuclear radiation. It transforms the charge that was produced inside of Silicon material as a result of the incidence of particles and X rays, in voltage pulses at the output of the preamplifier. In this work was made the adjustment of the technological process of manufacture of the detector. Also was made the design and construction of the cryostat and preamplifier and then the validation of the system in a Cuban Dewar. The system, which was made for the first time in our country, has an energy resolution of 185 eV for the Fe-55 source (E=5.9 KeV), which has permitted its implementation in energy dispersive X ray fluorescence. (author)

  15. X-ray flat panel detectors and X-ray tubes contributing to development of X-ray diagnostic systems

    International Nuclear Information System (INIS)

    X-ray flat panel detectors (FPDs) and X-ray tubes are key devices allowing X-ray diagnostic systems to support more sophisticated medical care. FPDs provide valuable information for the diagnosis of various diseases through the conversion of X-ray images of the human body into electronic signals, while X-ray tubes are used in a wide range of applications such as computed tomography (CT), angiography, fluoroscopy, mammography, and dental systems. Toshiba Electron Tubes and Devices Co., Ltd. has developed and commercialized FPDs providing high-quality diagnostic X-ray images with low dose exposure through the development of cutting-edge technologies including a fine crystal formation technology for cesium iodide (CsI) scintillators, thin-film transistor (TFT) arrays with photodiodes, and so on. In the field of X-ray tubes that can generate a high output of X-rays, we have developed a liquid metal hydrodynamic bearing (LM bearing) technology for various diagnostic systems including medical CT systems with a long lifetime and high rotation speed, and cardiovascular imaging systems with quiet operation. Furthermore, LM bearing technology reduces the burden on the environment by replacing insulating oil with water coolant for the cooling system and making the X-ray tubes more compact. (author)

  16. HIgh Rate X-ray Fluorescence Detector

    Energy Technology Data Exchange (ETDEWEB)

    Grudberg, Peter Matthew [XIA LLC

    2013-04-30

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

  17. The microcalorimeter X-ray detector: a true paradigm shift in X-ray spectroscopy

    International Nuclear Information System (INIS)

    The microcalorimeter x-ray detector registers the heat deposited in an absorber from individual x-ray photons by means of a sensitive thermometer. It combines advantages of wavelength-dispersive and energy-dispersive detectors: relatively high energy resolution over a broad energy spectrum. Operating at very low temperatures reduces the noise, making the high energy resolution possible. The absorber can be tailored to any energy range, from soft x-rays to gamma rays. After many years of development, several designs have reached a level of performance and reliability that makes them competitive x-ray detectors for many kinds of experiment. We survey current microcalorimeter detectors using several different thermometers. Their applications already run from chemical analysis to plasma physics and x-ray astronomy. We describe two examples of how the microcalorimeter detector can enable novel determinations in x-ray physics, one concerning the comparison of x-ray line energies and the other dealing with valence band x-ray emission spectra.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-03-01

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

  19. Small area silicon diffused junction x-ray detectors

    International Nuclear Information System (INIS)

    The low temperature performance of silicon diffused junction detectors in the measurement of low energy x-rays is reported. The detectors have an area of 0.04 cm2 and a thickness of 100 μm. The spectral resolutions of these detectors were found to be in close agreement with expected values indicating that the defects introduced by the high temperature processing required in the device fabrication were not deleteriously affecting the detection of low energy x-rays. Device performance over a temperature range of 77 to 1500K is given. These detectors were designed to detect low energy x-rays in the presence of minimum ionizing electrons. The successful application of silicon diffused junction technology to x-ray detector fabrication may facilitate the development of other novel silicon x-ray detector designs

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

    DEFF Research Database (Denmark)

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

    2008-01-01

    We report on the application of the PILATUS 100K pixel detector for medical imaging. Experimental results are presented in the form of X-ray radiographs using standard X-ray absorption contrast and a recently developed phase contrast imaging method. The results obtained with the PILATUS detector...

  1. New Detector Development for X-ray Astronomy Project

    Data.gov (United States)

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

  2. X-ray detectors with digitized preamplifiers

    International Nuclear Information System (INIS)

    With direct digitization of detector pulses, software algorithms are used to calculate the energy of incident photons. Fast high resolution sampling adc's and digital signal processors replace shaping amplifiers and spectroscopy adc's. The difference between the classical analog approach for pulse processing and direct digitization can be summarized as follows. In analog systems, a preamplifier output is filtered by analog means and then digitized to be acquired in a multichannel analyzer, whereas the full digital system will digitize first and then filter by application of algorithms. According to the sampling theorem, both approaches are equivalent. However, using digital signal processing for filtering allows the use of filter functions that cannot be practically realized with analog means. Those digital filter functions promise resolution and throughput close to the theoretical limit. The first commercially available ADSP (Analog to Digital Signal Processor) uses a moving window deconvolution to deconvolve the preamplifier characteristic. All algorithms are calculated in real time, thus there is no dead time added through the computation of an event. A filter function with a trapezoidal impulse response calculates the energy in real time. An adaptive digital trigger allows excellent low energy detection. Another benefit for X-ray applications are very long shaping constants, resulting in 125 eV resolution at 5.9 keV with SiLi detectors. The ADSP consists of an analog linear amplification stage, a 20 MHz sampling adc, circuits for digital signal preprocessing, and four floating point DSPs, performing 240 MFLOP/s. It has been built into a 2-wide NIM module to replace virtually any adc/shaping amplifier combination. (orig.)

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

    OpenAIRE

    Takaki Hatsui; Heinz Graafsma

    2015-01-01

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

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

    NARCIS (Netherlands)

    E.J. Schioppa

    2014-01-01

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

  5. A Sealed Gas Pixel Detector for X-ray Astronomy

    OpenAIRE

    Bellazzini, R.; Spandre, G.; Minuti, M.; Baldini, L; Brez, A.; Latronico, L; Omodei, N.; Razzano, M.; Massai, M. M.; Pinchera, M.; Pesce-Rollins, M.; SGRO, C.; Costa, E; P. Soffitta(a); Sipila, H.

    2006-01-01

    We report on the results of a new, sealed, Gas Pixel Detector. The very compact design and the absence of the gas flow system, make this detector substantially ready for use as focal plane detector for future X-ray space telescopes. The instrument brings high sensitivity to X-ray polarimetry, which is the last unexplored field of X-ray astronomy. It derives the polarization information from the track of the photoelectrons that are imaged by a high gain (>1000), fine pitch GEM that matches the...

  6. Gamma detector for use with luggage X-ray systems

    International Nuclear Information System (INIS)

    A new gamma radiation sensor has been designed for installation on several types of luggage x-ray machines and mobile x-ray vans operated by the U.S. Customs Service and the U.S. Department of State. The use of gamma detectors on x-ray machines imposed difficulties not usually encountered in the design of gamma detectors because the spectrum of scattered x-rays, which varied from machine to machine, extended to energies significantly higher than those of the low-energy isotopic emissions. In the original design, the lower level discriminator was raised above the x-ray end point energy resulting in the loss of the americium line associated with plutonium. This reduced the overall sensitivity to unshielded plutonium by a factor of approximately 100. An improved method was subsequently developed wherein collimation was utilized in conjunction with a variable counting threshold to permit accommodation of differing conditions of x-ray scattering. This design has been shown to eliminate most of the problems due to x-ray scattering while still capturing the americium emissions. The overall sensitivity has remained quite high, though varying slightly from one model of x-ray machine to another, depending upon the x-ray scattering characteristics of each model. (author)

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

    International Nuclear Information System (INIS)

    Microwave chemical vapor deposited (CVD) diamond films have been used to fabricate radiation detectors. The polycrystalline diamond films have a resistivity of 1012 ohm.cm and carrier mobility and lifetime of about 280 cm2/V.s and 530 ps. The detector response to laser pulses (355, 532 and 1064 nm), X-ray flux (15-50 keV) and alpha particles (241Am, 5.49 MeV) has been investigated. The response speed of the detector is in the 100 ps range. A sensitivity of about 3 x 10-10 A/V.Gy.s was measured under 50 keV X-ray flux. The detector current response to X-ray flux is almost linear. It is also shown that CVD diamond detectors can be used for alpha particle counting. (authors). 9 figs., 25 refs

  8. Indirectly illuminated X-ray area detector for X-ray photon correlation spectroscopy.

    Science.gov (United States)

    Shinohara, Yuya; Imai, Ryo; Kishimoto, Hiroyuki; Yagi, Naoto; Amemiya, Yoshiyuki

    2010-11-01

    An indirectly illuminated X-ray area detector is employed for X-ray photon correlation spectroscopy (XPCS). The detector consists of a phosphor screen, an image intensifier (microchannel plate), a coupling lens and either a CCD or CMOS image sensor. By changing the gain of the image intensifier, both photon-counting and integrating measurements can be performed. Speckle patterns with a high signal-to-noise ratio can be observed in a single shot in the integrating mode, while XPCS measurement can be performed with much fewer photons in the photon-counting mode. By switching the image sensor, various combinations of frame rate, dynamic range and active area can be obtained. By virtue of these characteristics, this detector can be used for XPCS measurements of various types of samples that show slow or fast dynamics, a high or low scattering intensity, and a wide or narrow range of scattering angles. PMID:20975218

  9. Low-temperature detectors in X-ray astronomy

    International Nuclear Information System (INIS)

    The most compelling nature of X-ray astronomy is its richness and scale. Almost every observable object in the sky either naturally emits X-ray radiation or can be observed through X-ray absorption. Current X-ray observatories such as Chandra and XMM-Newton have considerably advanced our understanding of many of these systems by using imaging X-ray cameras and dispersed X-ray spectrometers. However, it is the combination of these two techniques to provide a true broadband, high spectral-resolution, imaging spectrometer that will drive the next revolution in X-ray astronomy. This is where Low-temperature detectors (LTDs) can play a key role but also where the science will continuously challenge the technology. In this brief overview we will explore the constraints that both the science goals and the space environment place on the implementation of LTDs, how current missions such as XQC and Astro-E2 have met these challenges, and where future missions such as Constellation-X, XEUS, and NeXT will drive LTD instruments to a much larger scale. Finally, we will address scaling issues in current LTD detectors and where the LTD community needs to proceed to address both the science goals and expectations of the astrophysics community

  10. X-Ray Spectroscopy Using Low Temperature Detectors

    Science.gov (United States)

    Porter, Frederick

    2011-01-01

    After several decades of development, a significant amount of the effort in low temperature detectors (LTDs) is concentrated on deploying real-world experiments. This has resulted from a great deal of basic detector physics performed by several generations of students, post-docs, and researchers. One of the most fruitful applications of LTDs is in non-dispersive x-ray spectroscopy. LTD x-ray spectrometers are broadband, efficient, moderately high-resolution, and can handle moderately high count rates. However, they require significantly more power, mass, and infrastructure compared to traditional solid state x-ray spectrometers, and cannot achieve, at least at low energies, the resolving powers achieved with dispersive spectrometers. In several fields, however, LTDs have or will make a significant contribution. In this review, we will discuss x-ray spectroscopy in general, the fields of science where LTDs are making a significant impact, and some of the current and near-term LTD spectrometers.

  11. Digital X-ray detector based on a CCD matrix

    International Nuclear Information System (INIS)

    The application of charge-coupled devices (CCD) as position-sensitive detectors for X-ray radiation is discussed. The experimental scheme contains a videotransmission camera to detect pulsed X-ray radiation and Vektor analog-to-digital converters and computer interface. It is shown that the sensitivity range of a K1200TsM1 matrix to bremsstrahlung with an average energy of 75 keV is 2.7·10-8-0.8·10-6 J/cm2. The spatial resolution of the resultant X-ray image is discussed. 5 refs., 5 figs

  12. Gated x-ray detector for the National Ignition Facility

    International Nuclear Information System (INIS)

    Two new gated x-ray imaging cameras have recently been designed, constructed, and delivered to the National Ignition Facility in Livermore, CA. These gated x-Ray detectors are each designed to fit within an aluminum airbox with a large capacity cooling plane and are fitted with an array of environmental housekeeping sensors. These instruments are significantly different from earlier generations of gated x-ray images due, in part, to an innovative impedance matching scheme, advanced phosphor screens, pulsed phosphor circuits, precision assembly fixturing, unique system monitoring, and complete remote computer control. Preliminary characterization has shown repeatable uniformity between imaging strips, improved spatial resolution, and no detectable impedance reflections

  13. Dental x-ray spectrometry with cadmium telluride detectors

    International Nuclear Information System (INIS)

    Cadmium telluride (CdTe) semiconductor detectors provide high detection efficiency for use in the diagnostic x-rays energy range, due to the high atomic number and density of the crystal. This kind of detector has been utilized in diagnostic x-ray spectroscopy, mainly in the mammography energy range, but only scarce information about its use in dental x-ray beams has been published. In this way, a portable 3x3x1 mm3 CdTe solid state detector (XR-100T CdTe, Amptek, Inc.) with electronic system, tungsten pinhole collimators, alignment device and associated software was utilized in this work. A single-phase dental unit with adjustable kVp and mA was employed and the x-ray spectra were experimentally determined at 50, 60 and 70 kVp with a tube current of 0.5 mA and 1.5mm Al additional filtration. An experimental setup was developed to guarantee a perfect alignment between the detector and the focal spot. The detector to focal spot distance was 3.0 m. Two 2mm thick tungsten pinholes (Amptek EXVC kit) with 0.4 mm and 1.0 mm collimator aperture diameters were positioned close to the detector in order to reduce the pulse pile-up events at high counting rates. A stripping procedure was implemented to correct the pulse height distribution in order to determine the photon spectra. The calculation of the CdTe response, used to correct the measured spectra, was simulated using the GEANT4 Monte Carlo toolkit. The x-ray spectra were compared with the spectra obtained with a high-purity germanium detector (EGP200-13-TR, Eurisys Mesures) with associated electronic devices and software. The reasonable agreement between the results obtained with both detectors shows that CdTe detectors can be successfully utilized for dental x-ray spectrometry. (author)

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

    International Nuclear Information System (INIS)

    Compact, room temperature x-ray spectroscopy detectors are of interest in many areas including diagnostic x-ray imaging, radiation protection and dosimetry. Room temperature cadmium zinc telluride (CZT) semiconductor detectors are promising candidates for these applications. One of the major problems for CZT detectors is low-energy tailing of the energy spectrum due to hole trapping. Spectral post-correction methods to correct the tailing effect do not work well for a number of reasons; thus it is advisable to eliminate the hole trapping effect in CZT using physical methods rather than correcting an already deteriorated energy spectrum. One method is using a CZT detector with an electrode configuration which modifies the electric field in the CZT volume to decrease low-energy tailing. Another method is to irradiate the CZT surface at a tilted angle, which modifies depth of interaction to decrease low-energy tailing. Neither method alone, however, eliminates the tailing effect. In this work, we have investigated the combination of modified electric field and tilted angle irradiation in a single detector to further decrease spectral tailing. A planar CZT detector with 10 x 10 x 3 mm3 size and CZT detector with 5 x 5 x 5 mm3 size and cap-shaped electrode were used in this study. The cap-shaped electrode (referred to as CAPture technology) modifies the electric field distribution in the CZT volume and decreases the spectral tailing effect. The detectors were investigated at 900 (normal) and 300 (tilted angle) irradiation modes. Two isotope sources with 59.6 and 122 keV photon energies were used for gamma-ray spectroscopy experiments. X-ray spectroscopy was performed using collimated beams at 60, 80 and 120 kVp tube voltages, in both normal and tilted angle irradiation. Measured x-ray spectra were corrected for K x-ray escape fractions that were calculated using Monte Carlo methods. The x-ray spectra measured with tilted angle CAPture detector at 60, 80 and 120 kVp tube

  15. An x-ray detector for time-resolved studies

    International Nuclear Information System (INIS)

    The development of ultrahigh-brightness x-ray sources makes time-resolved x-ray studies more and more feasible. Improvements in x-ray optics components are also critical for obtaining the appropriate beam for a particular type of experiment. Moreover, fast parallel detectors will be essential in order to exploit the combination of high intensity x-ray sources and novel optics for time-resolved experiments. A CCD detector with a time resolution of microseconds has been developed at the Advanced Photon Source (APS). This detector is fully programmable using CAMAC electronics and a Micro Vax computer. The techniques of time-resolved x-ray studies, which include scattering, microradiography, microtomography, stroboscopy, etc., can be applied to a range of phenomena (including rapid thermal annealing, surface ordering, crystallization, and the kinetics of phase transition) in order to understand these time-dependent microscopic processes. Some of these applications will be illustrated by recent results performed at synchrotrons. New powerful x-ray sources now under construction offer the opportunity to apply innovative approaches in time-resolved work

  16. A nuclear spectrum generator for semiconductor X-ray detectors

    International Nuclear Information System (INIS)

    A nuclear spectrum generator for semiconductor X-ray detectors is designed in this paper. It outputs step ramp signals with random distribution in amplitude and time according to specified reference spectrum. The signals are similar to the signals from an actual semiconductor X-ray detector, and can be use to check spectrum response characteristics of an X-ray fluorometer. This helps improving energy resolution of the X-ray fluorometer. The spectrum generator outputs step ramp signals satisfying the probability density distribution function of any given reference spectrum in amplitude through sampling on the basis of 32-bit randomizer. The system splits 1024 interval segmentation of the time that the step ramp signals appear, and calculates the appearance probability of step ramp signals in different intervals and the average time between the time intervals, by random sampling. The step ramp signals can meet the rule of exponential distribution in time. Test results of the spectrum generator show that the system noise is less than 2.43 mV, the output step ramp signals meet the Poisson distribution in counting rate and the probability density distribution function of the reference spectrum in amplitude. The counting rate of the output step ramp signals can be adjusted. It meets the rule of the output signals from semiconductor X-ray detectors, such as Si-pin detector and silicon drift detector. (authors)

  17. Modeling and design of X-rays bidimensional detectors

    International Nuclear Information System (INIS)

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

  18. High-sensitivity CCD-based x-ray detector

    International Nuclear Information System (INIS)

    The detector is designed for imaging measurements requiring relatively high sensitivity and high spatial resolution. The detector can discriminate single X-ray photons, yet has the wide dynamic range (∼10000:1) associated with integrating detectors. A GdO2S2 phosphor screen converts the incoming X-ray image into an optical image. The optical image is coupled (without demagnification) to the CCD image sensor using a fiber optic faceplate. The CCD (Philips Semiconductors) has an area of 4.9 x 8.6 cm with 4000 x 7000 12 μm pixels. A single 12 keV X-ray photon produces a signal of 100 e-. With 2 x 2 pixel binning, the total noise per 24 μm pixel in a 100 s image is ∼30 e-, the detective quantum efficiency is >0.6 at 1 X-ray photon per pixel, and the full image can be read out in <4 s. The spatial resolution is 50 μm. The CCD readout system is fully computer-controlled, allowing flexible operation in time-resolved experiments. The detector has been characterized using visible-light images, X-ray images and time-resolved muscle diffraction measurements.

  19. Second-generation X-ray television area detectors

    International Nuclear Information System (INIS)

    X-ray television area detector diffractometry of single crystals has become an established technique for structure determination of biological macromolecules. As interest focuses on smaller crystals and larger unit cells, further improvements are needed in resolution and in signal-to-noise ratio; a detector diameter of about 150 mm has become desirable. These aims are being achieved by optimizing the X-ray phosphor, by a new design of image intensifier and by better optical coupling. New electronic circuitry is being developed to exploit the capability of these detectors of collecting complete diffraction data sets, containing about 0.5 Gb of information, in less than a minute at synchrotron radiation beam lines, some two to three orders of magnitude faster than by conventional methods with conventional X-ray sources. (orig.)

  20. Study of semiconductor detectors applied to diagnostic X-ray

    International Nuclear Information System (INIS)

    This work aims an evaluation of procedures for photons spectrum determination, produced by a X ray tube, normally used for medical diagnoses which operation voltage ranges from 20 to 150 kVp, to allow more precise characterization of the photon beam. The use of spectrum analysis will contribute to reduce the uncertainty in the ionization camera calibrations. For this purpose, two kind of detectors were selected, a Cadmium Zinc Telluride (CZT) and a planar HPGe detector. The X ray interaction with the detector's crystal produces, by electronic processes, a pulse high distribution as an output, which is no the true photon spectrum, due to the presence of K shell escape peaks, Compton scattering and to the fact that the detectors efficiency diminish rapidly with the increase of the photon energy. A detailed analysis of the contributing factors to distortions in the spectrum is necessary and was performed by Monte Carlo calculation with the MCNP 4B computer code. In order to determine the actual photon spectrum for a X ray tube a spectra stripping procedure is described for the HPGe detector. The detector's response curves, determined by the Monte Carlo calculation, were compared to the experimental ones, for isotropic point sources. For the methodology validation, stripped spectra were compared to the theoretical ones, for the same X ray tube's settings, for a qualitative evaluation. The air kerma rate calculated with the photon spectra were compared to the direct measurement using an ionization chamber, for a quantitative evaluation. (author)

  1. Flat-panel detectors in x-ray diagnosis

    International Nuclear Information System (INIS)

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

  2. Development of multiwire gas detectors for X-rays

    International Nuclear Information System (INIS)

    This work presents the prototype of a 2D position sensitive gas detector for application in X-ray scattering and diffraction experiments. Starting from a detector initially developed for other applications and will show the required changes on the original concept of this device. The strategy used to determine the necessary adaptations were based on searching in the literature for the overall characteristics of a multi-wire X-ray detector (choice of gas, pressure, window, etc.), the use of simulations, implementation of the changes and finally operational tests. Computational tools were used to calculate the mechanical strength and attenuation of the X-ray photons that helped to determine the most appropriate material for the construction of the entrance window. Detector simulations were built with Garfield software and were used to study the overall properties of the detector, and to determine the optimum parameters for the equipment operation. Typical parameters are the distance between the wires, wire diameter, high voltage to be used, among several other parameters. The results obtained showed that the multi-wire detector concept with the implemented adaptations allowed the detection of X-rays. However, depending on the application, it may be necessary improve the resolution of the equipment, in order to have a better description of the collected data. Several ideas are suggested for this improvement. It is also presented interesting results obtained with a microscopic pattern detector called triple GEM. This device belongs to the Gas Detectors Development group (GDD group) at CERN and was used in my training at this institution. The results showed the potential of the equipment for detection of X-rays. The results and simulations presented in this work, confirmed that the changes in the concept of the original detector permitted it use on X-ray detection applications. Also, it was possible to obtain several indications for further optimization, which may

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

    CERN Document Server

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

    1999-01-01

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

  4. Thermally stimulated investigations on diamond X-Ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Tromson, D.; Bergonzo, P.; Brambilla, A.; Mer, C.; Foulon, F. [CEA/Saclay, Dept. d' Electronique et d' Instrumentation Nucleaire (DEIN), 91 - Gif-sur-Yvette (France); Amosov, V.N. [TRINITI, Div. of Physics of Thermonuclear Reactors, Troitsk Moscow (Russian Federation)

    1999-07-01

    Intrinsic diamond material is increasingly used for the fabrication of radiation detectors. However, the presence of inherent defects has a strong impact on the detector characteristics such as the time dependent stability of the detection signal. In order to draw better insights into this effect, comparative investigations of the X-ray responses with thermally stimulated current (TSC) measurements were carried out on natural diamond detectors. TSC revealed the presence of four peaks or shoulders on natural samples in the 200 to 500 K domain. Three energy levels were identified at about 0.7, 0.71 and 0.95 eV. Time dependent X-ray detector sensitivity was investigated for various initial conditions. The results giveevidence of the improvement of the detection properties after having filled traps in the material by X-ray irradiation. The comparison between the X-ray response and the TSC spectra indicate that trapping levels emptied at room temperature appear to significantly affect the performance of radiation detectors. (authors)

  5. Thermally stimulated investigations on diamond X-Ray detectors

    International Nuclear Information System (INIS)

    Intrinsic diamond material is increasingly used for the fabrication of radiation detectors. However, the presence of inherent defects has a strong impact on the detector characteristics such as the time dependent stability of the detection signal. In order to draw better insights into this effect, comparative investigations of the X-ray responses with thermally stimulated current (TSC) measurements were carried out on natural diamond detectors. TSC revealed the presence of four peaks or shoulders on natural samples in the 200 to 500 K domain. Three energy levels were identified at about 0.7, 0.71 and 0.95 eV. Time dependent X-ray detector sensitivity was investigated for various initial conditions. The results give evidence of the improvement of the detection properties after having filled traps in the material by X-ray irradiation. The comparison between the X-ray response and the TSC spectra indicate that trapping levels emptied at room temperature appear to significantly affect the performance of radiation detectors. (authors)

  6. Investigation of Micropatent Gaseous Detector for X-ray Polarimetry

    Science.gov (United States)

    Liu, Hongbang; Liang, En-Wei; Liu, Qian; Zheng, Yangheng

    2016-07-01

    We present an investigation of the Micropatent Gaseous Detector (THGEM and MicroMegas) for the X-ray polarimeter. THGEMs with different thickness and diameter have been studied with vary electrical parameter. The energy resolution of 15.9% with 5.9 keV X-rays was obtained for the thinner-THGEM. MicroMegas with ITO glass has been assembled and tested in Ne-5%CF _{4} which emits light during the electron multiplication. The track of the primary photoelectron excited by the incident X-ray was imaged on an intensified CCD. For the expected sensitivity of the polarimeter, we used the Monte Carlo package Geant4 and Garfield to simulate the charge distribution of the photoelectron, diffusion of the charge track during drift and track image of the detector. The associated Monte Carlo calculation of energy resolution dependence on drift electric field and induction field has been compared with the experimental results.

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

    International Nuclear Information System (INIS)

    The recent results on development of X-ray Si(Li), Si-planar and CdTe p-i- n detectors cooled by Peltier coolers for fabrication of laboratory and portable XRF analysers for different applications are discussed. Low detection limits of XRF analysers are provided by increasing of detectors sensitive surface; improvement of their spectrometrical characteristics; decreasing of front-end-electronics noise level; Peltier coolers and vacuum chambers cooling modes optimization. Solution of all mentioned tasks allowed to develop Peltier cooled detectors with the following performances: (1) Si(Li) detectors: S = 20 mm2, thickness = 3.5 mm, 175 eV (5.9 keV), 430 eV (59.6 keV); S = 100 mm2; thickness = 4.5 mm, 270 eV (5.9 keV), 485 eV (59,6 keV). (2) Si-planar detector: S = 10 mm2, thickness = 0.4 mm, 230 eV (5.9 keV), 460 eV (59.6 keV). (3) CdTe p-i-n detectors: S = 16 mm2, thickness 0.5 mm, 350 eV (5.9 keV), 585 eV (59.6 keV). S = 16 mm2, thickness = 1.2 mm, 310 eV (5.9 keV), 600 eV (59.6 keV). Advantages and disadvantages of all types of detectors for X-ray fluorescence analysis are compared. Spectra are presented. Application of different XRF analysers based on developed detectors in medicine, environmental science, industry, criminalistics and history of art are demonstrated. (author)

  8. X-ray laminography with panel detector translation scan

    International Nuclear Information System (INIS)

    An advanced fast quasi-3D imaging method for inspecting moving object is presented. Using cone-beam X-ray and panel detector translation scan (PDTS), quasi-3D data of the object structure can be obtained just by one translation scan. (authors)

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

    Science.gov (United States)

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

    2014-07-01

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

  10. Effective and cheap X-ray television detector

    International Nuclear Information System (INIS)

    The position sensitive detector (PSD) is designed for investigations with traditional X-ray tubes and synchrotron radiation from 3 to 30 keV. PSD consists of light-tight box, which transforms X-ray photons to light photons. Light photons are registered with the help of TV camera. Then an image is digitized and introduced into computer. Software provides registration of the dim beam images by means of accumulation of the information. Statistic processing of the image series allows to determine of the parameters of the image. Sensitivity is 41 phot/pixel. Spatial resolution is not worse then 400 μ

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

    Science.gov (United States)

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

    2016-05-01

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

  12. X-ray detectors for soft X-ray macromolecular crystallography

    International Nuclear Information System (INIS)

    Full text: Modern protein crystallography ultimately makes use of the two-dimensional position - sensitive detectors such as Image Plates and CCD with scintillation convertors coupled with fiber optics for detection of X-Ray diffraction pictures taken from macromolecular crystals. These detectors have high efficiency for 1.5-1.0 A synchrotron radiation, special resolution ∼80-50 μm and large effective area (i.e. Σ 300 mm2 for large MAR Image Plate). Both of these types of detectors lack energy resolution. A major drawback of Image Plates is long read-out time (2.5-4 minutes). CCD based devices permit data collection in a real time, however at present they are much more expensive. One of the novel and very promising trends in protein crystallography is to use soft X-ray synchrotron radiation between 2.2 keV and 6 keV (5.6 to 2.5 A) and there is an urgent need to develop suitable detection system for these kinds of applications. It is to be two- dimensional positional sensitive detector with pitch of about 10 to 20 μm, high efficiency and real-time readout. An active area of the detector is to be at least 20 x 20 mm2. It seems to be the simplest solution to use conventional direct-illumination CCD detectors because absorption length of the 5 A radiation in silicon is about 3 μm. However they lack, for example, energy resolution and optimum solution of the problem has yet to come. (author)

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

    Science.gov (United States)

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

    2011-10-01

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

  14. New X-Ray Detector for Caltech Plasma Jet Experiment

    Science.gov (United States)

    Marshall, Ryan; Bellan, Paul

    2015-11-01

    Magnetic reconnection is a process that occurs in plasmas where magnetic field lines break and re-attach to form a different topology having lower energy. Since the magnetic field is changing very fast in the reconnection region, Faraday's Law states that there is a large electric field that accelerates electrons which can then create x-rays. X-rays have been previously observed in the Caltech plasma jet experiment and in similar experiments. We have assembled a new detector consisting of a scintillator that is more than 10 times the volume of the previous one and a light guide that allows the photomultiplier tube to be 2 meters from the experiment so that electrical noise is reduced. The setup has been tested using a weak natural Thorium source and will soon be mounted on the Caltech jet experiment in front of a kapton vacuum window that allows x-rays to pass. Kapton has good transmission above 5 KeV.

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

    Institute of Scientific and Technical Information of China (English)

    曹靖; 蒋春雨; 赵艳凤; 杨青巍; 阴泽杰

    2015-01-01

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

  16. Recent developments in X-ray imaging detectors

    CERN Document Server

    Moy, J P

    2000-01-01

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

  17. Area x-ray detectors for intense diffuse signals

    International Nuclear Information System (INIS)

    The problem of developing a suitable detector for x-ray diffraction by polymers for synchrotron radiation is pointed out as being a very pressing problem. Design, development, and implementation of synchrotron beams has been carried out by the laboratories, but the detector efforts have been left in the hands of the users. The design of an electro-optical detector designated as 2-DXD and consisting of three basic elements: an energy converter, a gain element, and a storage/readout device is described in detail

  18. Large area x-ray detectors for cargo radiography

    Science.gov (United States)

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

    2007-04-01

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

  19. An x-ray detector using superconducting aluminum tunnel junctions

    International Nuclear Information System (INIS)

    We report on tests of a prototype detector for 6-keV X-rays, using series arrays of tunnel junction. Tests with higher-energy particles indicate an energy resolution of 4 keV, at 0.3K and with a warm pre-amp. At lower temperatures and with a cooled FET, the resolution should approach 100 eV

  20. X-ray measurement with Pin type semiconductor detectors

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    Schioppa, Enrico Junior

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

  2. A Sealed Gas Pixel Detector for X-ray Astronomy

    CERN Document Server

    Bellazzini, R; Minuti, M; Baldini, L; Brez, A; Latronico, L; Omodei, N; Razzano, M; Massai, M M; Pinchera, M; Pesce-Rollins, M; Sgro, C; Costa, E; Soffitta, P; Sipilä, H; Lempinen, E

    2006-01-01

    We report on the results of a new, sealed, Gas Pixel Detector. The very compact design and the absence of the gas flow system, make this detector substantially ready for use as focal plane detector for future X-ray space telescopes. The instrument brings high sensitivity to X-ray polarimetry, which is the last unexplored field of X-ray astronomy. It derives the polarization information from the track of the photoelectrons that are imaged by a high gain (>1000), fine pitch GEM that matches the pitch of a pixel ASIC which is the collecting anode of the GPD (105k, 50 micron wide, hexagonal cells). The device is able to simultaneously perform good imaging (50-60 micron), moderate spectroscopy (~15% at 6 keV) as well as fast, high rate timing in the 1-10keV range. Moreover, being truly 2D, it is non dispersive and does not require any rotation. The great improvement of sensitivity, at least two orders of magnitude with respect to traditional polarimeters (based on Bragg crystals or Thomson scattering), will allow ...

  3. Flat-response x-ray-diode-detector development

    International Nuclear Information System (INIS)

    In this report we discuss the design of an improved sub-nanosecond flat response x-ray diode detector needed for ICF diagnostics. This device consists of a high Z cathode and a complex filter tailored to flatten the response so that the total x-ray energy below 1.5 keV can be measured using a single detector. Three major problems have become evident as a result of our work with the original LLNL design including deviation from flatness due to a peak in the response below 200 eV, saturation at relatively low x-ray fluences, and long term gold cathode instability. We are investigating grazing incidence reflection to reduce the response below 200 eV, new high Z cathode materials for long term stability, and a new complex filter for improved flatness. Better saturation performance will require a modified XRD detector under development with reduced anode to cathode spacing and increased anode bias voltage

  4. Measurements of Si hybrid CMOS x-ray detector characteristics

    Science.gov (United States)

    Bongiorno, Stephen D.; Falcone, Abraham D.; Burrows, David N.; Cook, Robert

    2010-07-01

    The recent development of active pixel sensors as X-Ray focal plane arrays will place them in contention with CCDs on future satellite missions. Penn State University (PSU) is working with Teledyne Imaging Sensors (TIS) to develop X-Ray Hybrid CMOS devices (HCDs), a type of active pixel sensor with fast frame rates, adaptable readout timing and geometry, low power consumption, and inherent radiation hardness. CCDs have been used with great success on the current generation of X-Ray telescopes (e.g. Chandra, XMM, Suzaku, and Swift). However, their bucket-brigade readout architecture, which transfers charge across the chip with discrete component readout electronics, results in clockrate limited readout speeds that cause pileup (saturation) of bright sources and an inherent susceptibility to radiation induced displacement damage that limits mission lifetime. In contrast, HCDs read pixels through the detector substrate with low power, on-chip readout integrated circuits. Faster frame rates, achieved with adaptable readout timing and geometry, will allow the next generation's larger effective area telescopes to observe brighter sources free of pileup. In HCDs, radiation damaged lattice sites affect a single pixel instead of an entire row. The PSU X-ray group is currently testing 4 Teledyne HCDs, with low cross-talk CTIA devices in development. We will report laboratory measurements of HCD readnoise, interpixel-capacitance and its impact on event selection, linearity, and energy resolution as a function of energy.

  5. Quality control measurements for digital x-ray detectors

    Science.gov (United States)

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

    2011-02-01

    This paper describes a digital radiography (DR) quality control protocol for DR detectors from the forthcoming report from the Institute of Physics and Engineering in Medicine (IPEM). The protocol was applied to a group of six identical caesium iodide (CsI) digital x-ray detectors to assess reproducibility of methods, while four further detectors were assessed to examine the wider applicability. Twelve images with minimal spatial frequency processing are required, from which the detector response, lag, modulation transfer function (MTF), normalized noise power spectrum (NNPS) and threshold contrast-detail (c-d) detectability are calculated. The x-ray spectrum used was 70 kV and 1 mm added copper filtration, with a target detector air kerma of 2.5 µGy for the NNPS and c-d results. In order to compare detector performance with previous imaging technology, c-d data from four screen/film systems were also acquired, at a target optical density of 1.5 and an average detector air kerma of 2.56 µGy. The DR detector images were typically acquired in 20 min, with a further 45 min required for image transfer and analysis. The average spatial frequency for the 50% point of the MTF for six identical detectors was 1.29 mm-1 ± 0.05 (3.9% coefficient of variation (cov)). The air kerma set for the six systems was 2.57 µGy ± 0.13 (5.0% cov) and the NNPS at this air kerma was 1.42 × 10-5 mm2 (6.5% cov). The detective quantum efficiency (DQE) measured for the six identical detectors was 0.60 at 0.5 mm-1, with a maximum cov of 10% at 2.9 mm-1, while the average DQE was 0.56 at 0.5 mm-1 for three CsI detectors from three different manufacturers. Comparable c-d performance was found for these detectors (5.9% cov) with an average threshold contrast of 0.46% for 11 mm circular discs. The average threshold contrast for the S/F systems was 0.70% at 11 mm, indicating superior imaging performance for the digital systems. The protocol was found to be quick, reproducible and gave an in

  6. Quality control measurements for digital x-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, N W [Department of Radiology, University Hospitals Leuven, 49 Herenstraat, 3000 Leuven (Belgium); Mackenzie, A [National Co-ordinating Centre for the Physics of Mammography, Medical Physics, Level B, St Luke' s Wing, The Royal Surrey County Hospital NHS Trust, Egerton Road, Guildford, GU2 7XX (United Kingdom); Honey, I D, E-mail: nicholas.marshall@uz.kuleuven.ac.be [Department of Medical Physics, Floor 3, Henriette Raphael House, Guy' s and St Thomas' Hospital, London, SE1 9RT (United Kingdom)

    2011-02-21

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

  7. A sealed Gas Pixel Detector for X-ray astronomy

    International Nuclear Information System (INIS)

    We report on the results of a new, sealed Gas Pixel Detector. The very compact design and the absence of the gas flow system make this detector substantially ready for use as focal plane detector for future X-ray space telescopes. The instrument brings high sensitivity to X-ray polarimetry, which is the last unexplored field of X-ray astronomy. It derives the polarization information from the track of the photoelectrons that are imaged by a high-gain (>1000), fine pitch GEM that matches the pitch of a pixel ASIC which is the collecting anode of the GPD (105k, 50 μm wide, hexagonal cells). The device is able to simultaneously perform good imaging (50-60 μm), moderate spectroscopy (∼15% at 6 keV) as well as fast, high-rate timing in the 1-10 keV range. Moreover, being truly 2D, it is non-dispersive and does not require any rotation. The great improvement of sensitivity, at least two orders of magnitude with respect to traditional polarimeters (based on Bragg crystals or Thomson scattering), will allow the direct exploration of the most dramatic objects of the X-ray sky. At the focus of the large mirror area of the XEUS telescope it will be decisive in reaching many of the scientific goals of the mission. With integration times of the order of 1 day, polarimetry of Active Galactic Nuclei at the percent level will be possible, making for a real breakthrough in high-energy astrophysics

  8. A sealed Gas Pixel Detector for X-ray astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Bellazzini, R. [INFN sez.Pisa, Largo B. Pontecorvo 3, I-56127 Pisa (Italy)], E-mail: ronaldo.bellazzini@pi.infn.it; Spandre, G.; Minuti, M.; Baldini, L.; Brez, A.; Latronico, L.; Omodei, N. [INFN sez.Pisa, Largo B. Pontecorvo 3, I-56127 Pisa (Italy); Razzano, M.; Massai, M.M. [INFN sez.Pisa, Largo B. Pontecorvo 3, I-56127 Pisa (Italy); Dipartimento di Fisica, Universita di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa (Italy); Pesce-Rollins, M.; Sgro, C. [INFN sez.Pisa, Largo B. Pontecorvo 3, I-56127 Pisa (Italy); Costa, Enrico; Soffitta, Paolo [Istituto di Astrofisica Spaziale e Fisica Cosmica, Via del Fosso del Cavaliere 100, I-00133, Roma (Italy); Sipila, H.; Lempinen, E. [Oxford Instruments Analytical Oy, Nihtisillankuja 5, FI-02631 Espoo (Finland)

    2007-09-01

    We report on the results of a new, sealed Gas Pixel Detector. The very compact design and the absence of the gas flow system make this detector substantially ready for use as focal plane detector for future X-ray space telescopes. The instrument brings high sensitivity to X-ray polarimetry, which is the last unexplored field of X-ray astronomy. It derives the polarization information from the track of the photoelectrons that are imaged by a high-gain (>1000), fine pitch GEM that matches the pitch of a pixel ASIC which is the collecting anode of the GPD (105k, 50 {mu}m wide, hexagonal cells). The device is able to simultaneously perform good imaging (50-60 {mu}m), moderate spectroscopy ({approx}15% at 6 keV) as well as fast, high-rate timing in the 1-10 keV range. Moreover, being truly 2D, it is non-dispersive and does not require any rotation. The great improvement of sensitivity, at least two orders of magnitude with respect to traditional polarimeters (based on Bragg crystals or Thomson scattering), will allow the direct exploration of the most dramatic objects of the X-ray sky. At the focus of the large mirror area of the XEUS telescope it will be decisive in reaching many of the scientific goals of the mission. With integration times of the order of 1 day, polarimetry of Active Galactic Nuclei at the percent level will be possible, making for a real breakthrough in high-energy astroph0011ysi.

  9. Energy dispersive x-ray analysis using a microcalorimeter detector

    International Nuclear Information System (INIS)

    The application of microcalorimeter-based energy dispersive x-ray spectroscopy (EDS) analysis to high-performance integrated circuit (IC) barrier layers for copper metallization is presented. Microcalorimeter EDS analysis of ternary TaSiN films are compared to that carried out using conventional Si(Li) EDS detectors. The elimination of elemental peak overlaps provided by the improved energy resolution of the microcalorimeter-based detector is demonstrated for the TaSiN spectra and is used to examine the efficacy of such an approach for electron microscopy-based compositional analysis of ultra-thin barrier films currently being investigated for giga-scale ICs

  10. Advances in silicon carbide X-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bertuccio, Giuseppe, E-mail: Giuseppe.Bertuccio@polimi.it [Politecnico di Milano, Department of Electronics Engineering and Information Science, Como Campus, Via Anzani 42, 22100 Como (Italy); National Institute of Nuclear Physics, INFN sez. Milano (Italy); Caccia, Stefano [Politecnico di Milano, Department of Electronics Engineering and Information Science, Como Campus, Via Anzani 42, 22100 Como (Italy); Puglisi, Donatella; Macera, Daniele [Politecnico di Milano, Department of Electronics Engineering and Information Science, Como Campus, Via Anzani 42, 22100 Como (Italy); National Institute of Nuclear Physics, INFN sez. Milano (Italy)

    2011-10-01

    The latest advances in SiC X-ray detectors are presented: a pixel detector coupled to a custom ultra low noise CMOS preamplifier has been characterized at room and high temperature. An equivalent noise energy (ENE) of 113 eV FWHM, corresponding to 6.1 electrons r.m.s., has been achieved with the detector/front-end system operating at +30 {sup o}C. A Fano factor of F=0.10 has been estimated from the {sup 55}Fe spectrum. When the system is heated up to +100 {sup o}C, the measured ENE is 163 eV FWHM (8.9 electrons r.m.s.). It is determined that both at room and at high temperature the performance are fully limited by the noise of the front-end electronics. It is also presented the capability of SiC detectors to operate in environments under unstable temperature conditions without any apparatus for temperature stabilization; it has been proved that a SiC detector can acquire high resolution X-ray spectra without spectral line degradation while the system temperature changes between +30 and +75 {sup o}C.

  11. Self-propelled x-ray flaw detector

    International Nuclear Information System (INIS)

    A self-propelled X-ray flaw detector for radiographic inspection of welded joints in pipelines comprises a carriage mounting a motor, a detector having two Geiger counters, a pulsed X-ray generator, and an exposure and carriage electronic control system. A memory unit in the control system has four storage elements containing information about the motion of the carriage. As the carriage moves in direction A, first one and then the other of the Geiger counters receives radiation from an isotope source positioned near a joint, and by means of logic circuitry in the control system, the information in the storage elements is modified to stop the carriage and to operate a timer to expose the weld. During exposure the X-rays may interfere with the information in the storage elements, but by means of a square-wave generator and the logic circuitry, the stored information is correctly reset in order to eliminate false operation of the memory unit. (author)

  12. Radio and X-ray emission from newly born remnants

    International Nuclear Information System (INIS)

    Radio and X-ray observations of SN 1979c and SN 1980k offer a unique opportunity of monitoring the transition from supernovae to remnants. By means of the two-frequency radio light curves, the hypothesis that these objects are surrounded by circumstellar matter, originated in a presupernova wind, is tested, and the relevant parameters are derived. Then the absorption-corrected light curves are used to test the various proposed models. SN 1980k appears to be powered by a canonical shock, while SN 1979c is a good plerion candidate. An optical pulsar could still be detected at its location. (Auth.)

  13. Characterization of an indirect X-ray imaging detector by simulation and experiment.

    Science.gov (United States)

    Doshi, C; van Riessen, G; Balaur, E; de Jonge, M D; Peele, A G

    2015-01-01

    We describe a comprehensive model of a commercial indirect X-ray imaging detector that accurately predicts the detector point spread function and its dependence on X-ray energy. The model was validated by measurements using monochromatic synchrotron radiation and extended to polychromatic X-ray sources. Our approach can be used to predict the performance of an imaging detector and can be used to optimize imaging experiments with broad-band X-ray sources. PMID:25203971

  14. Development of a fast X-ray detector

    International Nuclear Information System (INIS)

    A gas scintillation drift counter has been developed. This counter, which is capable of working in a digital mode at a quite high rate without producing space charge effects has been modified as a high counting rate X-ray detector. Scintillation and transport properties of an argon/nitrogen gas mixture have been studied using an Am241 alpha-particle source and an Fe55 5.9 keV radioactive X-ray source in order to obtain relative compositions of argon and nitrogen. The effects of various operating parameters on the energy resolution of the counter and the characteristics of output pulses have been extensively studied. Pulse responses, gain variations with counting rate and stability of the photomultiplier used to detect scintillation light have been investigated using a light emitting diode pulsar, a constant light source and primary scintillation pulses from 6.9 keV X-rays. The dynode potentials have been stabilised using emitter follower configurations. Energy and time resolution performances are given. A counting rate of 9.5 MHz is possible at the expense of energy resolution. (U.K.)

  15. Phonon effects in STJ X-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Andrianov, V.A. E-mail: andrva@srdlan.npi.msu.su; Dmitriev, P.N.; Koshelets, V.P.; Kozin, M.G.; Romashkina, I.L.; Sergeev, S.A.; Shpinel, V.S

    2000-04-07

    Influence of the phonon effects on the output signal of superconducting tunnel X-ray detectors was studied for junctions of two types: the standard Nb/Al/AlO{sub x}/Nb junctions and the multilayer asymmetric Nb/Al/AlO{sub x}/Al/Nb/NbN junctions with the proximity Al trapping layer. It was shown that phonon exchange can change the shape, the amplitude and the polarity of the signal. The most pronounced effects were observed in asymmetric junctions for the signals from the electrode with higher gap.

  16. A photon counting pixel detector for X-ray imaging

    International Nuclear Information System (INIS)

    Hybrid semiconductor pixel detector technology is presented in this thesis as an alternative to current imaging systems in medical imaging and synchrotron radiation applications. The technology has been developed from research performed in High Energy Physics, in particular, for the ATLAS experiment at the LHC, planned for 2005. This thesis describes work done by the author on behalf of the MEDIPIX project, a collaboration between 13 international institutions for the development of hybrid pixel detectors for non-HEP applications. Chapter 1 describes the motivation for these detectors, the origin of the technology, and the current state of the art in imaging devices. A description of the requirements of medical imaging on X-ray sensors is described, and the properties of film and CCDs are discussed. The work of the RD19 collaboration is introduced to show the evolution of these devices. Chapter 2 presents the basic semiconductor theory required to understand the operation of these detectors, and a section on image theory introduces the fundamental parameters which are necessary to define the quality of an imaging device. Chapter 3 presents measurements made by the author on a photon counting detector (PCD1) comprising a PCC1 (MEDIPIX1) readout chip bumpbonded to silicon and gallium arsenide pixel detectors. Tests on the seperate readout chip and the bump-bonded assembly are shown with comparisons between the performance of the two materials. Measurements of signal-to-noise ratio, detection efficiency and noise performance are presented, along with an MTF measurement made by the Freiburg group. The X-ray tube energy spectrum was calibrated by REGAM. The performance of the PCD in a powder diffraction experiment using a synchrotron radiation source is described in chapter 4. This chapter reports the first use of a true 2-D hybrid pixel detector in a synchrotron application, and a comparison with the existing scintillator based technology is made. The measurements made

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

    Science.gov (United States)

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

    2015-09-01

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

  18. STJ X-ray detectors with titanium sublayer

    Energy Technology Data Exchange (ETDEWEB)

    Kozin, M.G.; Romashkina, I.L. E-mail: irom@srd.sinp.msu.ru; Sergeev, S.A.; Nefedov, L.V.; Andrianov, V.A.; Naumkin, V.N.; Koshelets, V.P.; Filippenko, L.V

    2004-03-11

    Superconducting tunnel junctions (STJs) with the structure Ti/Nb/Al, AlO{sub x}/Al/Nb/NbN and corresponding layer thickness 30/100/8/13/150/30 nm were investigated as X-ray detectors at T=1.35 K. STJs with one active electrode in which the response of the other one is suppressed due to trapping layer on the surface opposite to the tunnel barrier have a number of potential advantages. The best line width (FWHM) is 78 eV for 6400 {mu}m{sup 2} junction. Contribution of the electronic noise is about 50 eV. The intrinsic detector line width is less than 60 eV. The collected charge from inactive electrode is more than 8 times less than that from the active one. Titanium proved to be an appropriate material for a sublayer and a trap.

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

    CERN Document Server

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

    2013-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

  1. Detector for the spectroscopy of hard X-ray transitions

    International Nuclear Information System (INIS)

    New possibilities are opened up utilizing position-sensitive germanium detectors in the X-ray spectroscopy of highly charged heavy ions at GSI-Darmstadt. The recent experiments revealed the need for two-dimensional strip detectors with their inherent advantages concerning spectroscopy and imaging capabilities as well as polarization sensitivity. For the first prototype a germanium diode (70 mm x 41 mm, 11 mm thick) with a boron implanted contact and an amorphous Ge contact was prepared. A 128-strip structure on an area of 32 mm x 56 mm with a pitch of 250 μm on the front contact (implanted) and a 48-strip structure with a pitch of 1167 μm on the rear contact (amorphous Ge) are realized with the help of plasma etching. The detector is mounted in a cryostat which will enable any orientation of the detector with respect to a photon source. The results of laboratory tests and planned applications at the ESR storage ring in Darmstadt are presented. (orig.)

  2. Characterization of an indirect X-ray imaging detector by simulation and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Doshi, C.; Riessen, G. van; Balaur, E. [Department of Physics, La Trobe University, Victoria 3086 (Australia); Centre of Excellence for Coherent X-ray Science, La Trobe University, Victoria 3086 (Australia); Jonge, M.D. de [Australian Synchrotron, Victoria 3168 (Australia); Peele, A.G. [Department of Physics, La Trobe University, Victoria 3086 (Australia); Centre of Excellence for Coherent X-ray Science, La Trobe University, Victoria 3086 (Australia); Australian Synchrotron, Victoria 3168 (Australia); Centre of Excellence for Advanced Molecular Imaging, Australian Synchrotron, Victoria 3168 (Australia)

    2015-01-15

    We describe a comprehensive model of a commercial indirect X-ray imaging detector that accurately predicts the detector point spread function and its dependence on X-ray energy. The model was validated by measurements using monochromatic synchrotron radiation and extended to polychromatic X-ray sources. Our approach can be used to predict the performance of an imaging detector and can be used to optimize imaging experiments with broad-band X-ray sources. - Highlights: • We modeled the point spread function of an indirect X-ray imaging detector. • The effects of optical coupling between detector components were included. • The model was validated with monochromatic and polychromatic X-ray source. • The geometrical arrangement for optimal detector resolution was identified.

  3. Photoemission measurements for low energy x-ray detector applications

    International Nuclear Information System (INIS)

    Photoemission has been studied for nearly 100 years as both a means of investigating quantum physics, and as a practical technique for transducing optical/x-ray photons into electrical currents. Numerous x-ray detection schemes, such as streak cameras and x-ray sensitive diodes, exploit this process because of its simplicity, adaptability, and speed. Recent emphasis on diagnostics for low temperature, high density, and short-lived, plasmas for inertial confinement fusion has stimulated interest in x-ray photoemission in the sub-kilovolt regime. In this paper, a review of x-ray photoemission measurements in the 50 eV to 10 keV x-ray region is given and the experimental techniques are reviewed. A semiempirical model of x-ray photoemission is discussed and compared to experimental measurements. Finally, examples of absolutely calibrated instruments are shown

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

    CERN Document Server

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

    2006-01-01

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

  5. A large area detector for x-ray applications

    International Nuclear Information System (INIS)

    A large area detector for x-ray synchrotron applications has been developed. The front end of this device consist of a scintillator coupled to a fiber-optic taper. The fiber-optic taper is comprised of 4 smaller (70 mm x 70 mm) tapers fused together in a square matrix giving an active area of 140 mm x 140 mm. Each taper has a demagnification of 5.5 resulting in four small ends that are 12 mm diagonally across. The small ends of each taper are coupled to four microchannel-plate-based image intensifiers. The output from each image intensifier is focused onto a Charge Coupled Device (CCD) detector. The four CCDs are read out in parallel and are independently controlled. The image intensifiers also act as fast (20 ns) electronic shutters. The system is capable of displaying images in real time. Additionally, with independent control on the readout of each row of data from the CCD, the system is capable of performing high speed imaging through novel readout manipulation

  6. Radioisotope decontamination of X-ray detector. Photostimulable phosphor plate

    International Nuclear Information System (INIS)

    We tried to remove contamination of radioisotope (RI) for an X-ray detector (photostimulable phosphor plate; IP) and verified that our procedure suggested by Nishihara et al. was effective for decontamination. The procedure was as follows. First, the IP was kept for approximately twelve hours, and then it was processed [image (A)] as well as a clinical processing mode. Second, using a wet-type chemical wiper, we scavenged the IP to remove the adhered RI on its surface. Then, once again, the IP was kept for approximately fifteen hours and processed [image (B)] in order to check an effect of decontamination. Finally, the two images of (A) and (B) were analyzed using ImageJ, which can be downloaded as a free software, and a percentage of removal was calculated. The procedure was applied to two IPs using the Fuji computed tomography (FCR) 5501 plus. In the present case, the percentage of removal was approximately 96%. The removed radioisotopes in the chemical wipers were analyzed by Ge detector. Then, 134Cs and 137Cs were found with activities of 2.9 4.3 Bq and 3.5 5.2 Bq, respectively. For three months after that, we cannot see black spots on the IPs owing to the contamination of the RI and there are no defects caused by decontamination using a wet-type chemical wiper. (author)

  7. A flat-panel x-ray detector for digital radiography and fluoroscopy

    International Nuclear Information System (INIS)

    A Flat-Panel X-ray detector is widely used for digital radiography and fluoroscopy. The outline of the detectors such as the structure, working principle, performance and clinical applications that are newly developed using this digital X-ray detector are described. An X-ray detector applying CdZnTe film which is expected to high detective efficiency is also reported. The characteristics of poly crystalline CdZnTe films, namely grain boundary affect the detector performance. To improve performance of the CdZnTe detector, control of the poly crystalline structure is required. (author)

  8. Efficiency calibration of an HPGe X-ray detector for quantitative PIXE analysis

    International Nuclear Information System (INIS)

    Particle Induced X-ray Emission (PIXE) is an analytical technique, which provides reliably and accurately quantitative results without the need of standards when the efficiency of the X-ray detection system is calibrated. The ion beam microprobe of the Ion Beam Modification and Analysis Laboratory at the University of North Texas is equipped with a 100 mm2 high purity germanium X-ray detector (Canberra GUL0110 Ultra-LEGe). In order to calibrate the efficiency of the detector for standard less PIXE analysis we have measured the X-ray yield of a set of commercially available X-ray fluorescence standards. The set contained elements from low atomic number Z = 11 (sodium) to higher atomic numbers to cover the X-ray energy region from 1.25 keV to about 20 keV where the detector is most efficient. The effective charge was obtained from the proton backscattering yield of a calibrated particle detector

  9. The CdZnTe detector in the measurement of mammographic x-ray spectra

    Energy Technology Data Exchange (ETDEWEB)

    Miyajima, Satoshi; Imagawa, Kotaro [Osaka Univ., Graduate School of Medicine, Course of Health Sciences, Suita, Osaka (Japan); Matsumoto, Masao [Osaka Univ., School of Allied Health Sciences, Faculty of Medicine, Suita, Osaka (Japan)

    2001-09-01

    As a mammographic x-ray unit has geometrical restrictions, large detectors cannot be used in experiments. We employed a Cd{sub 0.9}Zn{sub 0.1}Te (CZT) detector as an x-ray spectrometer in this study. An excellent response of the CZT detector can be expected in mammographic energy range: the energy of x-rays is relatively low ({approx}35keV), and the main components of the x-rays are around 20keV in mammography. (author)

  10. REBIRTH OF X-RAY EMISSION FROM THE BORN-AGAIN PLANETARY NEBULA A30

    International Nuclear Information System (INIS)

    The planetary nebula A30 is believed to have undergone a very late thermal pulse resulting in the ejection of knots of hydrogen-poor material. Using multi-epoch Hubble Space Telescope images, we have detected the angular expansion of these knots and derived an age of 850+280–150 yr. To investigate the spectral and spatial properties of the soft X-ray emission detected by ROSAT, we have obtained Chandra and XMM-Newton deep observations of A30. The X-ray emission from A30 can be separated into two components: a point source at the central star and diffuse emission associated with the hydrogen-poor knots and the cloverleaf structure inside the nebular shell. To help us assess the role of the current stellar wind in powering this X-ray emission, we have determined the stellar parameters and wind properties of the central star of A30 using a non-LTE model fit to its optical and UV spectra. The spatial distribution and spectral properties of the diffuse X-ray emission are highly suggestive that it is generated by the post-born-again and present fast stellar winds interacting with the hydrogen-poor ejecta of the born-again event. This emission can be attributed to shock-heated plasma, as the hydrogen-poor knots are ablated by the stellar winds, under which circumstances the efficient mass loading of the present fast stellar wind raises its density and damps its velocity to produce the observed diffuse soft X-rays. Charge transfer reactions between the ions of the stellar winds and material of the born-again ejecta have also been considered as a possible mechanism for the production of diffuse X-ray emission, and upper limits on the expected X-ray production by this mechanism have been derived. The origin of the X-ray emission from the central star of A30 is puzzling: shocks in the present fast stellar wind and photospheric emission can be ruled out, while the development of a new, compact hot bubble confining the fast stellar wind seems implausible.

  11. Application of a pnCCD in X-ray diffraction: a three-dimensional X-ray detector.

    Science.gov (United States)

    Leitenberger, Wolfram; Hartmann, Robert; Pietsch, Ullrich; Andritschke, Robert; Starke, Ines; Strüder, Lothar

    2008-09-01

    The first application of a pnCCD detector for X-ray scattering experiments using white synchrotron radiation at BESSY II is presented. A Cd arachidate multilayer was investigated in reflection geometry within the energy range 7 keV frames at a readout rate of 200 Hz. By representing the data in reciprocal-space coordinates, it becomes obvious that this experiment with the pnCCD detector provides the same information as that obtained by combining a large number of monochromatic scattering experiments using conventional area detectors. PMID:18728315

  12. Double-Layer Silicon PIN Photodiode X-Ray Detector for a Future X-ray Timing Mission

    OpenAIRE

    Feng, Hua; Kaaret, Philip; Andersson, Hans

    2006-01-01

    A double-layer silicon detector consisting of two 500micron-thick silicon PIN photodiodes with independent readouts was mounted in a vacuum chamber and tested with X-ray sources. The detector is sensitive from 1-30 keV with an effective area of 6 mm^2. The detector performs best at -35 C with an energy resolution of 220 eV (FWHM, full width at half maximum) at 5.9 keV, and is able to operate at room temperature, +25 C, with moderate resolution around 760 eV (FWHM). The response of the top lay...

  13. THE BORN-AGAIN PLANETARY NEBULA A78: AN X-RAY TWIN OF A30

    Energy Technology Data Exchange (ETDEWEB)

    Toalá, J. A.; Guerrero, M. A.; Marquez-Lugo, R. A.; Fang, X. [Instituto de Astrofísica de Andalucía IAA-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada (Spain); Todt, H.; Hamann, W.-R.; Oskinova, L. M. [Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, D-14476 Potsdam (Germany); Chu, Y.-H.; Gruendl, R. A. [Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801 (United States); Schönberner, D. [Leibniz-Institut Für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Ramos-Larios, G., E-mail: toala@iaa.es [Instituto de Astronomía y Meteorología, Av. Vallarta No. 2602, Col. Arcos Vallarta, 44130 Guadalajara (Mexico)

    2015-01-20

    We present the XMM-Newton discovery of X-ray emission from the planetary nebula (PN) A78, the second born-again PN detected in X-rays apart from A30. These two PNe share similar spectral and morphological characteristics: they harbor diffuse soft X-ray emission associated with the interaction between the H-poor ejecta and the current fast stellar wind and a point-like source at the position of the central star (CSPN). We present the spectral analysis of the CSPN, using for the first time an NLTE code for expanding atmospheres that takes line blanketing into account for the UV and optical spectra. The wind abundances are used for the X-ray spectral analysis of the CSPN and the diffuse emission. The X-ray emission from the CSPN in A78 can be modeled by a single C VI emission line, while the X-ray emission from its diffuse component is better described by an optically thin plasma emission model with a temperature of kT = 0.088 keV (T ≈ 1.0 × 10{sup 6} K). We estimate X-ray luminosities in the 0.2-2.0 keV energy band of L {sub X,} {sub CSPN} = (1.2 ± 0.3) × 10{sup 31} erg s{sup –1} and L {sub X,} {sub DIFF} = (9.2 ± 2.3) × 10{sup 30} erg s{sup –1} for the CSPN and diffuse components, respectively.

  14. Balloon-Borne Hard X-Ray Imaging and Future Surveys

    CERN Document Server

    Grindlay, J E

    1997-01-01

    Several payloads for hard X-ray (20-600 keV) imaging with coded aperture telescopes have been developed for balloon flight observations of cosmic x-ray sources. We briefly review the characteristics of these, particularly the EXITE2 system. The recent NASA program to develop an extended long duration (100d) balloon flight capability employing super-pressure balloons would allow a qualitatively new hard x-ray imaging experiment: the Energetic X-ray Imaging Survey Telescope-Long Integration Time Experiment (EXIST-LITE). The longer continuous viewing times (per source) available from an LDB platform than from low earth orbit would enable both surveys and objectives complementary to the EXIST mission proposed for a MIDEX satellite. We summarize the scientific objectives of EXIST-LITE, a possible instrumentation approach incorporating a large area array of Cd-Zn-Te (CZT) detectors, and our program for the development and balloon flight testing of relatively thick (5mm) CZT detector arrays.

  15. Vacuum photodiode detectors for soft x-ray ITER plasma tomography

    Science.gov (United States)

    Gott, Yu. V.; Stepanenko, M. M.

    2005-07-01

    A special type of vacuum photodiode detector (VPD) for x-ray tomography of (ITER) plasma is described. Laboratory experiments demonstrate that VPD has high sensitivity to thermal x-rays and low sensitivity to hard gamma rays and neutrons. It was shown that in ITER environment the signal due to thermal x-rays will surpass the background signal by more than a factor of 100.

  16. Vacuum photodiode detectors for soft x-ray ITER plasma tomography

    International Nuclear Information System (INIS)

    A special type of vacuum photodiode detector (VPD) for x-ray tomography of (ITER) plasma is described. Laboratory experiments demonstrate that VPD has high sensitivity to thermal x-rays and low sensitivity to hard gamma rays and neutrons. It was shown that in ITER environment the signal due to thermal x-rays will surpass the background signal by more than a factor of 100

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

    CERN Document Server

    Hashimoto, Ryo; Kumai, Reiji; Kishimoto, Shunji

    2015-01-01

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

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

    CERN Document Server

    Wei Biao; Che Zhen Ping

    2002-01-01

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

  19. Developments of position-sensitive X-ray detectors at SPring-8

    CERN Document Server

    Toyokawa, H; Hirota, K

    2003-01-01

    In order to efficiently perform diffraction and scattering experiments at the SPring-8 facility, three types of position sensitive detectors have been developed. A silicon pixel detector could detect X-rays above 6-keV in single counting mode, and an image accumulated could be read out within 5 msec. A 128-channel microstrip Germanium detector has made it possible for the users to efficiently investigate high resolution Compton scattering experiments. A high energy X-ray imager with a 128 x 128 matrix of YAP crystal has been developed for high energy X-ray diffraction experiments. (author)

  20. In-situ X-ray diffraction system using sources and detectors at fixed angular positions

    Science.gov (United States)

    Gibson, David M.; Gibson, Walter M.; Huang, Huapeng

    2007-06-26

    An x-ray diffraction technique for measuring a known characteristic of a sample of a material in an in-situ state. The technique includes using an x-ray source for emitting substantially divergent x-ray radiation--with a collimating optic disposed with respect to the fixed source for producing a substantially parallel beam of x-ray radiation by receiving and redirecting the divergent paths of the divergent x-ray radiation. A first x-ray detector collects radiation diffracted from the sample; wherein the source and detector are fixed, during operation thereof, in position relative to each other and in at least one dimension relative to the sample according to a-priori knowledge about the known characteristic of the sample. A second x-ray detector may be fixed relative to the first x-ray detector according to the a-priori knowledge about the known characteristic of the sample, especially in a phase monitoring embodiment of the present invention.

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

    Directory of Open Access Journals (Sweden)

    Pacella D

    2015-01-01

    Full Text Available Danilo Pacella ENEA-Frascati, Rome, Italy Abstract: This paper presents recent progress in the field of X-ray detectors, which could play a role in medical imaging in the near future, with special attention to the new generation of complementary metal-oxide semiconductor (C-MOS imagers, working in photon counting, that opened the way to the energy-resolved X-ray imaging. A brief description of the detectors used so far in medical imaging (photographic films, imaging plates, flat panel detectors, together with the most relevant imaging quality parameters, shows differences between, and advantages of these new C-MOS imagers. X-ray energy-resolved imaging is very attractive not only for the increase of contrast but even for the capability of detecting the nature and composition of the material or tissue to be investigated. Since the X-ray absorption coefficients of the different parts or organs of the patient (object are strongly dependent on the X-ray photon energy, this multienergy ("colored" X-ray imaging could increase enormously the probing capabilities. While dual-energy imaging is now a reality in medical practice, multienergy is still in its early stage, but a promising research activity. Based on this new technique of color X-ray imaging, the entire scheme of source–object–detector could be revised in the future, optimizing spectrum and detector to the nature and composition of the target to be investigated. In this view, a transition to a set of monoenergetic X-ray lines, suitably chosen in energy and intensity, could be envisaged, instead of the present continuous spectra. Keywords: X-ray detectors, X-ray medical imaging, C-MOS imagers, dual and multienergy CT

  2. Performance of a small-field digital detector for soft x-ray imaging

    Science.gov (United States)

    Seifert, Allen; Flynn, Michael J.; Shah, Manjul; Nagarkar, Vivek V.

    2001-06-01

    X-ray imaging detectors capable of very high resolution for a small field of view are important for x-ray micro-tomography, small specimen radiography, and certain x-ray scattering experiments. We have investigated the performance of small field detectors using scintillation phosphors coupled to a scientific CCD detector. The specific detector designs considered had fields of 8-12 mm that were used to record x-ray energies of 8-20 keV. The purpose of this work is to report the resolution (MTF) of designs that employed different optical coupling methods and different scintillation phosphor materials. For one detector system with a thin Gd2O2S phosphor a resolution of 48 lp/mm (presampled MTF = 0.10) was measured with pixels of 10.54 microns (Nyquist = 47.44) and a field of view of 12.14 mm x 13.09 mm.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kreisler, Bjoern

    2010-02-08

    -Carlo simulation of the irradiation head of the medical linear accelerator is constructed for the irradiation with electrons and photons in the second part of this thesis. The simulation is validated by comparison with water phantom measurements. Available information from the measurements is limited to the depth dose deposition and dose profiles in selected water depths. The simulation allows the evaluation of dose depositions and spectral particle distributions at various locations. In the electron irradiation mode, a collimation close to the patient is performed by an electron applicator. A possible reduction of the side leakage is evaluated by optimising the collimation of the beam. Medical irradiation with MeV-electrons and X-ray photons is the part of the clinical tumour treatment which is evaluated in this work. (orig.)

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

    International Nuclear Information System (INIS)

    the irradiation head of the medical linear accelerator is constructed for the irradiation with electrons and photons in the second part of this thesis. The simulation is validated by comparison with water phantom measurements. Available information from the measurements is limited to the depth dose deposition and dose profiles in selected water depths. The simulation allows the evaluation of dose depositions and spectral particle distributions at various locations. In the electron irradiation mode, a collimation close to the patient is performed by an electron applicator. A possible reduction of the side leakage is evaluated by optimising the collimation of the beam. Medical irradiation with MeV-electrons and X-ray photons is the part of the clinical tumour treatment which is evaluated in this work. (orig.)

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2013-12-01

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

  7. A bidimensional xenon-filled MWPC X-ray imaging detector for biomedical applications

    International Nuclear Information System (INIS)

    The X-ray imaging system developed at the Rutherford Laboratory for biomedical applications is described. It consists of a bidimensional, xenon-filled MWPC operating at NTP, and capable of detecting x-rays of energies up to approximately 50 keV. The chamber data is processed in a PDP-11 computer which is capable of storing and processing the x-ray images so as to provide good pictures of biological structures with a spatial resolution of approximately 2mm. Special attention has been paid to an application in the field of x-ray absorptiometry using monochromatic x-rays of approximately 42 keV and promising results are being obtained. Other potential applications are discussed. Particular attention is drawn to the usefulness of pulse height selection in improving the spatial resolution and imaging capability of an atmospheric pressure MWPC x-ray detector. (author)

  8. [Methods of detector response function establishment in X-ray fluorescence spectra analysis].

    Science.gov (United States)

    Li, Zhe; Tuo, Xian-Guo; Yang, Jian-Bo; Liu, Ming-Zhe; Cheng, Yi; Wang, Lei; Zhou, Jian-Bin

    2012-11-01

    During the measurement and analysis process of X-ray fluorescence spectra, it is very helpful to improve the analyze speed, accuracy and automaticity of X-ray fluorescence spectra analysis by establishing detector response function(DRF), which represents the shape of full energy peak and can provide former basic data for subsequent X-ray analysis technique. For the theory and model of semiconductor DRF in X-ray energy spectrum measurements, methods of three typical detector response function model establishment, key parameters of full energy peak standard deviation and Fano factor calculation, etc. are discussed, and meanwhile, the summarization and contrast of existing studies are shown in this paper. Finally, the suggestion for modeling methods of DRF in X-ray fluorescence spectra measurements is provided. PMID:23387190

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

    Indian Academy of Sciences (India)

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

    2000-04-01

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

  10. Detector characterization for ultra-high resolution X-ray laminography

    Energy Technology Data Exchange (ETDEWEB)

    Ebensperger, Thomas; Hanke, Randolf [Lehrstuhl fuer Roentgenmikroskopie, Julius-Maximilians-Universitaet Wuerzburg, Josef-Martin-Weg 63, 97074 Wuerzburg (Germany); Fraunhofer Entwicklungszentrum Roentgentechnik (EZRT), Dr.-Mack-Str. 81, 90762 Fuerth (Germany); Rimbach, Charlotte; Zabler, Simon [Lehrstuhl fuer Roentgenmikroskopie, Julius-Maximilians-Universitaet Wuerzburg, Josef-Martin-Weg 63, 97074 Wuerzburg (Germany)

    2013-07-01

    3D X-ray imaging is a very important tool in both medicine and materials characterization. We present an ultra-high resolution X-ray laminography system based on a thin-film X-ray transmission target which is coupled to an electron probe micro analyzer. Unlike in axial tomography 3D imaging is realized through a linear translation of both detector and object with respect to the source. A characterization of the spatial resolution of the detector has to be performed both under direct and under oblique illumination (i.e., at large laminography angles). This characterization comprises imaging of resolution test structures, determination of modulation transfer function and sensitivity and the simulation of the detector response using the Monte Carlo X-ray simulation tool ROSI. Based on these measurements and simulations we develop possibilities and algorithms to approach the position-dependent behavior of the detector in order to achieve the highest image quality.

  11. Detector characterization for ultra-high resolution X-ray laminography

    International Nuclear Information System (INIS)

    3D X-ray imaging is a very important tool in both medicine and materials characterization. We present an ultra-high resolution X-ray laminography system based on a thin-film X-ray transmission target which is coupled to an electron probe micro analyzer. Unlike in axial tomography 3D imaging is realized through a linear translation of both detector and object with respect to the source. A characterization of the spatial resolution of the detector has to be performed both under direct and under oblique illumination (i.e., at large laminography angles). This characterization comprises imaging of resolution test structures, determination of modulation transfer function and sensitivity and the simulation of the detector response using the Monte Carlo X-ray simulation tool ROSI. Based on these measurements and simulations we develop possibilities and algorithms to approach the position-dependent behavior of the detector in order to achieve the highest image quality.

  12. Recent trends of X-ray detectors in synchrotron radiation science

    CERN Document Server

    Suzuki, M

    2003-01-01

    This article attempts to describe the recent trends of X-ray detectors in synchrotron radiation science in the light of not only the advance but also the stagnation of which are seriously dependent upon the current semiconductor technology. (author)

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

    OpenAIRE

    Engel, K.J.; C. Herrmann

    2011-01-01

    Abstract: A pixelated X-ray semiconductor detector (=“direct converter”) is studied which contains an inhomogeneous electric field parallel to the depth axis caused by different concentrations of p- or n-doping. The X-ray energy deposition and charge movement within the detector is modeled in Monte-Carlo simulations which give access to astatistical analysis of electron drift times and current pulse widths for various degrees of static polarization. Integral charges induced on the pixel elect...

  14. Evaluation of digital x-ray detectors for medical imaging applications

    OpenAIRE

    Konstantinidis, A.

    2011-01-01

    Digital x-ray detectors are now the detector of choice in many X-ray examinations. They have been accepted into clinical practice over the past decade but there are still ongoing developments in the technology. Complementary metal oxide semiconductor (CMOS) active pixel sensors (APS) are a novel digital technology that offers advantages compared to some of the more established approaches (charge-coupled devices (CCD), thin film transistor arrays (TFT) and CMOS passive pixel sensors (PPS)). Th...

  15. Novel detector design for reducing intercell x-ray cross-talk in the variable resolution x-ray CT scanner: a Monte Carlo study

    OpenAIRE

    Arabi, Hosein; Asl, Ali Reza Kamali; Ay, Mohammad Reza; Zaidi, Habib

    2011-01-01

    The variable resolution x-ray (VRX) CT scanner provides substantial improvement in the spatial resolution by matching the scanner's field of view (FOV) to the size of the object being imaged. Intercell x-ray cross-talk is one of the most important factors limiting the spatial resolution of the VRX detector. In this work, a new cell arrangement in the VRX detector is suggested to decrease the intercell x-ray cross-talk. The idea is to orient the detector cells toward the opening end of the det...

  16. Development of optical switching readout X-ray detector for high-speed imaging

    International Nuclear Information System (INIS)

    In this study, we demonstrated the feasibility of an X-ray detector with a dual amorphous-selenium (a-Se) layer using an optical switching readout for high-speed X-ray imaging. The X-ray detector consists of a negative voltage bias electrode; a thick a-Se layer for the photoelectric conversion of X-ray photons; an As2Se3 layer employed as an electron-trapping layer for accumulating latent images; a thin a-Se layer for optical readout; alternate opaque and transparent electrodes; and an optical light source for the optical switching readout. The line light of the optical light source, which has a peak wavelength of 470 nm, is operated line by line using electrical scanning for high-speed X-ray imaging. The developed X-ray detector has a pixel pitch of 200 μm with 512 channels. -- Highlights: •The feasibility of X-ray detector for high-speed imaging was demonstrated. •An a-Se was used for optical switching layer for signal charge readout. •As2Se3 layer was employed as electron-trapping layer for accumulating latent images. •The surface light source of blue lights was fabricated for optical switching readout. •The 2D array of readout light can be emitted linearly and scanned electrically line by line

  17. Development of optical switching readout X-ray detector for high-speed imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ryun Kyung, E-mail: rkkim@keri.re.kr [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan-si (Korea, Republic of); Jeon, Sung Chae [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan-si (Korea, Republic of); Kim, Jung-Seok [Advanced Research Group, DRTECH Corporation, Seongnam-si (Korea, Republic of); Lee, Ho-Jun [School of Electrical Engineering, Pusan National University, Busan (Korea, Republic of); Heo, Duchang; Cha, Bo Kyung; Seo, Chang-Woo [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan-si (Korea, Republic of); Moon, B.J.; Yoon, J.K. [Advanced Research Group, DRTECH Corporation, Seongnam-si (Korea, Republic of)

    2013-12-11

    In this study, we demonstrated the feasibility of an X-ray detector with a dual amorphous-selenium (a-Se) layer using an optical switching readout for high-speed X-ray imaging. The X-ray detector consists of a negative voltage bias electrode; a thick a-Se layer for the photoelectric conversion of X-ray photons; an As{sub 2}Se{sub 3} layer employed as an electron-trapping layer for accumulating latent images; a thin a-Se layer for optical readout; alternate opaque and transparent electrodes; and an optical light source for the optical switching readout. The line light of the optical light source, which has a peak wavelength of 470 nm, is operated line by line using electrical scanning for high-speed X-ray imaging. The developed X-ray detector has a pixel pitch of 200 μm with 512 channels. -- Highlights: •The feasibility of X-ray detector for high-speed imaging was demonstrated. •An a-Se was used for optical switching layer for signal charge readout. •As{sub 2}Se{sub 3} layer was employed as electron-trapping layer for accumulating latent images. •The surface light source of blue lights was fabricated for optical switching readout. •The 2D array of readout light can be emitted linearly and scanned electrically line by line.

  18. Novel detector design for reducing intercell x-ray cross-talk in the variable resolution x-ray CT scanner: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Arabi, Hosein; Asl, Ali Reza Kamali; Ay, Mohammad Reza; Zaidi, Habib [Department of Radiation Medicine, Shahid Beheshti University, 1983963113 Tehran (Iran, Islamic Republic of); Research Centre for Science and Technology in Medicine, Tehran University of Medical Sciences, 1417613151 Tehran (Iran, Islamic Republic of); Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, 1417613151 Tehran (Iran, Islamic Republic of); and Research Institute for Nuclear Medicine, Tehran University of Medical Sciences, 1417613151 Tehran (Iran, Islamic Republic of); Division of Nuclear Medicine, Geneva University Hospital, CH-1211 Geneva (Switzerland); Geneva Neuroscience Center, Geneva University, CH-1211 Geneva (Switzerland) and Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, 9700 RB Groningen (Netherlands)

    2011-03-15

    Purpose: The variable resolution x-ray (VRX) CT scanner provides substantial improvement in the spatial resolution by matching the scanner's field of view (FOV) to the size of the object being imaged. Intercell x-ray cross-talk is one of the most important factors limiting the spatial resolution of the VRX detector. In this work, a new cell arrangement in the VRX detector is suggested to decrease the intercell x-ray cross-talk. The idea is to orient the detector cells toward the opening end of the detector. Methods: Monte Carlo simulations were used for performance assessment of the oriented cell detector design. Previously published design parameters and simulation results of x-ray cross-talk for the VRX detector were used for model validation using the GATE Monte Carlo package. In the first step, the intercell x-ray cross-talk of the actual VRX detector model was calculated as a function of the FOV. The obtained results indicated an optimum cell orientation angle of 28 deg. to minimize the x-ray cross-talk in the VRX detector. Thereafter, the intercell x-ray cross-talk in the oriented cell detector was modeled and quantified. Results: The intercell x-ray cross-talk in the actual detector model was considerably high, reaching up to 12% at FOVs from 24 to 38 cm. The x-ray cross-talk in the oriented cell detector was less than 5% for all possible FOVs, except 40 cm (maximum FOV). The oriented cell detector could provide considerable decrease in the intercell x-ray cross-talk for the VRX detector, thus leading to significant improvement in the spatial resolution and reduction in the spatial resolution nonuniformity across the detector length. Conclusions: The proposed oriented cell detector is the first dedicated detector design for the VRX CT scanners. Application of this concept to multislice and flat-panel VRX detectors would also result in higher spatial resolution.

  19. Pixel array detector for X-ray free electron laser experiments

    Energy Technology Data Exchange (ETDEWEB)

    Philipp, Hugh T., E-mail: htp2@cornell.edu [Department of Physics, Laboratory of Solid State Physics, Cornell University, Ithaca, NY 14853 (United States); Hromalik, Marianne [Electrical and Computer Engineering, SUNY Oswego, Oswego, NY 13126 (United States); Tate, Mark; Koerner, Lucas [Department of Physics, Laboratory of Solid State Physics, Cornell University, Ithaca, NY 14853 (United States); Gruner, Sol M. [Department of Physics, Laboratory of Solid State Physics, Cornell University, Ithaca, NY 14853 (United States); Wilson Laboratory, Cornell University, CHESS, Ithaca, NY 14853 (United States)

    2011-09-01

    X-ray free electron lasers (XFELs) promise to revolutionize X-ray science with extremely high peak brilliances and femtosecond X-ray pulses. This will require novel detectors to fully realize the potential of these new sources. There are many current detector development projects aimed at the many challenges of meeting the XFEL requirements . This paper describes a pixel array detector (PAD) that has been developed for the Coherent X-ray Imaging experiment at the Linac Coherent Light Source (LCLS) at the SLAC National Laboratory . The detector features 14-bit in-pixel digitization; a 2-level in-pixel gain setting that can be used to make an arbitrary 2-D gain pattern that is adaptable to a particular experiment; the ability to handle instantaneous X-ray flux rates of 10{sup 17} photons per second; and continuous frames rates in excess of 120 Hz. The detector uses direct detection of X-rays in a silicon diode. The charge produced by the diode is integrated in a pixilated application specific integrated circuit (ASIC) which digitizes collected holes with single X-ray photon capability. Each ASIC is 194x185 pixels, each pixel is 110{mu}mx110{mu}m on a side. Each pixel can detect up to 2500 X-rays per frame in low-gain mode, yet easily detects single photons at high-gain. Cooled, single-chip detectors have been built and meet all the required specifications. SLAC National Laboratory is engaged in constructing a tiled, multi-chip 1516x1516 pixel detector.

  20. Soft-X-ray measurements in WEST using GEM detectors

    Czech Academy of Sciences Publication Activity Database

    Mazon, D.; Vezinet, D.; Malard, P.; Chernyshova, M.; Czarski, T.; Jakubowska, K.; Kasprowicz, G.; Pozniak, K.; Rzadkiewicz, J.; Scholz, M.; Mlynář, Jan; Zabolotny, W.; Zagórski, R.

    Mulhouse : European Physical Society, 2013, P6.011-P6.011. ISBN 2-914771-84-3. - (Europhysics Conference Abstracts (ECA)). [European Physical Society Conference on Plasma Physics/40./. Espoo (FI), 01.07.2013-05.07.2013] Institutional support: RVO:61389021 Keywords : tokamak * diagnostics soft x-rays * tomography Subject RIV: BL - Plasma and Gas Discharge Physics http://ocs.ciemat.es/EPS2013PAP/pdf/P6.011.pdf

  1. X-ray microscopy utilizing world largest photon counting detector

    Czech Academy of Sciences Publication Activity Database

    Rudolf, Jiří; Kumpová, Ivana; Vavřík, Daniel; Jakůbek, Jan

    Brno : Central European Institute of Technology, 2015. s. 143-143 ISBN N. [Creating life in 3D. Conference on frontiers in materials and life sciences. 02.09.2015-04.09.2015, Brno] R&D Projects: GA MŠk(CZ) LO1219 Keywords : X-ray imaging techniques * dual-source tomography scanner * WidePIX Subject RIV: AL - Art, Architecture, Cultural Heritage http://www.ceitec.eu/a5-abstracts-book-3d/f33102

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

    CERN Document Server

    Koerner, Lucas J

    2010-01-01

    Dynamic x-ray studies may 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 (CHESS) at levels of up to 3.7x10^3 x-rays/pixel/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. This device is appropriate for time-resolved Bragg spot single crystal experiments.

  3. The development and characterization of neutron-damaged GaAs x-ray detectors

    International Nuclear Information System (INIS)

    Photoconductive x-ray detectors are becoming an important x-ray diagnostic as a result of their small size, fast response time, and high sensitivity. We are developing a discrete array of neutron- damaged GaAs detectors to be used in an imaging x-ray spectrometer, and we describe herein the techniques we use to fabricate and characterize them for an upcoming experiment. Using a 225-ps x-ray pulse from a laser-produced plasma, we measured the sensitivity and time response of the detectors to be 7.1 mA/W and on the order of 150 ps FWHM, respectively. The carrier mobility is 741 cm2/V/center dot/s at a bias of 2 /times/ 104V/cm. 6 figs

  4. New CdTe photoconductor array detector for x-ray applications

    International Nuclear Information System (INIS)

    A CdTe photoconductor array x-ray detector was grown using molecular beam epitaxy (MBE) on a Si(100) substrate. The temporal response of the photoconductor arrays is as fast as 21 ps rise time and 38 ps full width half-maximum (FWHM). The spatial resolution of the photoconductor was good enough to provide 75 μm FWHM using a 50 μm synchrotron x-ray beam. A substantial number of x-ray photons are absorbed effectively within the MBE CdTe layer as observed from the linear response up to 15 keV. These results demonstrate that MBE grown CdTe is a suitable choice of the detector materials to meet the requirements for x-ray detectors

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

    International Nuclear Information System (INIS)

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

  6. Energy dependence evaluation of a ZnO detector for diagnostic X-ray beam

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-01

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

  8. Building Large Area CZT Imaging Detectors for a Wide-Field Hard X-ray Telescope - ProtoEXIST1

    CERN Document Server

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

    2009-01-01

    We have constructed a moderately large area (32 cm2), fine pixel (2.5 mm pixel, 5 mm thick) CZT imaging detector which constitutes the first section of a detector module (256 cm2) 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 2 cm x 2 cm 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 (512 cm2) withi...

  9. Place of HgI2 energy-dispersive x-ray detectors

    International Nuclear Information System (INIS)

    After a review of solid-state conduction counters, in general, and of the history of mercuric iodide, in particular, the theory of operation of solid-state energy-dispersive HgI2 detectors is dicusssed. The main factors which limit energy resolution in solid-state compound detectors are considered, including statistical fluctuations in charge generation, the window effect, trapping, inhomogeneities in the detector material, and electronic noise. Potential applications of room-temperature HgI2 x-ray detectors are listed, and general considerations are discussed for x-ray fluorescence analysis with HgI2. Directions of current investigations are given

  10. Development of CdZnTe X-ray detectors at DSRI

    DEFF Research Database (Denmark)

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

    An overview of the development of CdZnTe X-ray detectors at the Danish Space Research Institute is presented. Initiated in the beginning of 1996, the main motivation at that time was to develop focal plane detectors for the novel type of hard X-ray telescopes, which are currently under study at...... DSRI. With the advent of the Danish Micro Satellite program it was, however, recognised that this type of detector is very well suited for two proposed missions (eXCALIBur, AXO). The research at DSRI has so far been concentrated on the spectroscopic properties of the CZT detector. At DSRI we have...

  11. Applications of 'edge-on' illuminated porous plate detectors for diagnostic X-ray imaging

    CERN Document Server

    Shikhaliev, P M

    2002-01-01

    Scanning X-ray imaging systems for non-invasive diagnostics have several advantages over conventional imaging systems using area detectors. They significantly reduce the detected scatter radiation, cover large areas and potentially provide high spatial resolution. Applications of one-dimensional gaseous detectors and 'edge-on' illuminated silicon strip detectors for scanning imaging systems are currently under intensive investigation. The purpose of this work is to investigate 'edge-on' illuminated Porous Plate (PP) detectors for applications in diagnostic X-ray imaging. MicroChannel Plate (MCP), which is a common type of PP, has previously been investigated as a detector in surface-on illumination mode for medical X-ray imaging. However, its detection efficiency was too low for medical imaging applications. In the present study, the PP are used in the 'edge-on' illumination mode. Furthermore, the structural parameters of different PP types are optimized to improve the detection efficiency in the diagnostic X...

  12. Design considerations for soft X-ray television imaging detectors

    International Nuclear Information System (INIS)

    Television sensors for X-rays can be coupled to converters and image intensifiers to obtain active areas, high flux capabilities, quantum efficiency, high time resolution, or ease of construction and operation that may not be obtained with a directly illuminated sensor. A general purpose system which makes use of these capabilities for a number of applications is decribed. Some of the performance characteristics of this type of system are examined, and the expected future developments for such systems are briefly addressed. 19 refs

  13. Efficiency calibration of an HPGe X-ray detector for quantitative PIXE analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mulware, Stephen J., E-mail: Stephenmulware@my.unt.edu; Baxley, Jacob D., E-mail: jacob.baxley351@topper.wku.edu; Rout, Bibhudutta, E-mail: bibhu@unt.edu; Reinert, Tilo, E-mail: tilo@unt.edu

    2014-08-01

    Particle Induced X-ray Emission (PIXE) is an analytical technique, which provides reliably and accurately quantitative results without the need of standards when the efficiency of the X-ray detection system is calibrated. The ion beam microprobe of the Ion Beam Modification and Analysis Laboratory at the University of North Texas is equipped with a 100 mm{sup 2} high purity germanium X-ray detector (Canberra GUL0110 Ultra-LEGe). In order to calibrate the efficiency of the detector for standard less PIXE analysis we have measured the X-ray yield of a set of commercially available X-ray fluorescence standards. The set contained elements from low atomic number Z = 11 (sodium) to higher atomic numbers to cover the X-ray energy region from 1.25 keV to about 20 keV where the detector is most efficient. The effective charge was obtained from the proton backscattering yield of a calibrated particle detector.

  14. CdZnTe x-ray detector for 30 {endash} 100 keV energy

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, S.-S. [Illinois Univ., Chicago, IL (United States). Dept. of Physics][Argonne National Lab., IL (United States); Rodricks, B.; Shastri, S.D. [Argonne National Lab., IL (United States); Montano, P.A. [Illinois Univ., Chicago, IL (United States). Dept. of Physics][Argonne National Lab., IL (United States)

    1996-07-01

    High-pressure-Bridgman (HPB) grown CdZnTe x-ray detectors 1.25-1.7 mm thick were tested using monochromatic x-rays of 30 to 100 keV generated by a high energy x-ray generator. The results were compared with a commercially available 5 cm thick NaI detector. A linear dependence of the counting rate versus the x-ray generator tube current was observed at 58.9 keV. The measured pulse height of the photopeaks shows a linear dependence on energy. Electron and hole mobility-lifetime products ({mu}{tau}) were deduced by fitting bias dependent photopeak channel numbers at 30 keV x-ray energy. Values of 2 x 10{sup -3} cm{sup 2}/V and 2 x 10{sup -4}cm{sup 2}/V were obtained for {mu}{tau}{sub e} and {mu}{tau}{sub p}, respectively. The detector efficiency of CdZnTe at a 100 V bias was as high as, or higher than 90 % compared to a NaI detector. At x-ray energies higher than 70 keV, the detection efficiency becomes a dominant factor and decreases to 75 % at 100 keV.

  15. New developments of an X-ray television area detector

    International Nuclear Information System (INIS)

    The Enraf-Nonius FAST system consists of a TV-camera based detector, combined with a four circle goniometer with kappa type geometry and is interfaced to a micro VAX computer and a TV monitor. The detector has recently been equipped with a new image intensifier, due to which the point spread of the detector at the one percent level has been drastically reduced. A comparison between the old and the new type detector is shown. A crystallographic data collection with the two detectors shows the big improvement due to this change in the FAST detector. (orig.)

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

    Science.gov (United States)

    Shikhaliev, Polad M

    2009-08-21

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

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

    International Nuclear Information System (INIS)

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

  18. Spectrometry of X-ray beams using Cadmium and Zinc Teluride detector

    International Nuclear Information System (INIS)

    Determination of X-ray spectra to be utilized for medical diagnostics is a complementary process to the development of procedures to be applied to the quality control of radiodiagnostics X-ray equipment. Until some years ago, that was only possible using Germanium or Silicon detectors. Both have an excellent resolution in this energy range, but present also some restrictions as there are high costs and the necessity of operating them at temperature of liquid Nitrogen, which is not always available at the measurement's place. Room temperature detectors like Cadmium Telluride and Mercury Iodine don't have these restrictions. They, however, have a lower resolution and incomplete collection of the charges produced by their interaction with radiation. With technological advance of crystal growth in general and new techniques like cooling the crystal with a Peltier cell and rise time discrimination circuits, today Cadmium Telluride detectors show a resolution very close to that from Germanium detectors. This work relates to the routine use of Cadmium and Zinc Telluride detectors for measuring X-ray spectra in loco of diagnostic X-ray units. It characterizes the properties of a commercially available detector and offers a model for stripping the measured pulse height distribution. It was also developed a collimator to allow the direct measurement of the beam. The model developed and the constructed set-up were applied to two X-ray tubes and the achieved spectra compared with some spectra available from the literature. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-05

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

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

    Science.gov (United States)

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

    2015-12-01

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

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

    CERN Document Server

    Kishimoto, S; Ito, M

    2001-01-01

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

  2. Note: Application of a pixel-array area detector to simultaneous single crystal x-ray diffraction and x-ray absorption spectroscopy measurements

    International Nuclear Information System (INIS)

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

  3. Characterization and development of an event-driven hybrid CMOS x-ray detector

    Science.gov (United States)

    Griffith, Christopher

    2015-06-01

    Hybrid CMOS detectors (HCD) have provided great benefit to the infrared and optical fields of astronomy, and they are poised to do the same for X-ray astronomy. Infrared HCDs have already flown on the Hubble Space Telescope and the Wide-Field Infrared Survey Explorer (WISE) mission and are slated to fly on the James Webb Space Telescope (JWST). Hybrid CMOS X-ray detectors offer low susceptibility to radiation damage, low power consumption, and fast readout time to avoid pile-up. The fast readout time is necessary for future high throughput X-ray missions. The Speedster-EXD X-ray HCD presented in this dissertation offers new in-pixel features and reduces known noise sources seen on previous generation HCDs. The Speedster-EXD detector makes a great step forward in the development of these detectors for future space missions. This dissertation begins with an overview of future X-ray space mission concepts and their detector requirements. The background on the physics of semiconductor devices and an explanation of the detection of X-rays with these devices will be discussed followed by a discussion on CCDs and CMOS detectors. Next, hybrid CMOS X-ray detectors will be explained including their advantages and disadvantages. The Speedster-EXD detector and its new features will be outlined including its ability to only read out pixels which contain X-ray events. Test stand design and construction for the Speedster-EXD detector is outlined and the characterization of each parameter on two Speedster-EXD detectors is detailed including read noise, dark current, interpixel capacitance crosstalk (IPC), and energy resolution. Gain variation is also characterized, and a Monte Carlo simulation of its impact on energy resolution is described. This analysis shows that its effect can be successfully nullified with proper calibration, which would be important for a flight mission. Appendix B contains a study of the extreme tidal disruption event, Swift J1644+57, to search for

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

    Institute of Scientific and Technical Information of China (English)

    LI Mei; JU Hong-jun

    2008-01-01

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

  5. Nanosecond X-ray detector based on high resistivity ZnO single crystal semiconductor

    Science.gov (United States)

    Zhao, Xiaolong; Chen, Liang; He, Yongning; Liu, Jinliang; Peng, Wenbo; Huang, Zhiyong; Qi, Xiaomeng; Pan, Zijian; Zhang, Wenting; Zhang, Zhongbing; Ouyang, Xiaoping

    2016-04-01

    The pulse radiation detectors are sorely needed in the fields of nuclear reaction monitoring, material analysis, astronomy study, spacecraft navigation, and space communication. In this work, we demonstrate a nanosecond X-ray detector based on ZnO single crystal semiconductor, which emerges as a promising compound-semiconductor radiation detection material for its high radiation tolerance and advanced large-size bulk crystal growth technique. The resistivity of the ZnO single crystal is as high as 1013 Ω cm due to the compensation of the donor defects (VO) and acceptor defects (VZn and Oi) after high temperature annealing in oxygen. The photoconductive X-ray detector was fabricated using the high resistivity ZnO single crystal. The rise time and fall time of the detector to a 10 ps pulse electron beam are 0.8 ns and 3.3 ns, respectively, indicating great potential for ultrafast X-ray detection applications.

  6. Capturing dynamics with Eiger, a fast-framing X-ray detector

    International Nuclear Information System (INIS)

    A high-frame-rate single-photon-counting pixel detector named Eiger and its suitability for X-ray photon correlation spectroscopy are described. Eiger is the next-generation single-photon-counting pixel detector following the widely used Pilatus detector. Its smaller pixel size of 75 µm × 75 µm, higher frame rate of up to 22 kHz, and practically zero dead-time (∼4 µs) between exposures will further various measurement methods at synchrotron sources. In this article Eiger’s suitability for X-ray photon correlation spectroscopy (XPCS) is demonstrated. By exploiting its high frame rate, complementary small-angle X-ray scattering (SAXS) and XPCS data are collected in parallel to determine both the structure factor and collective diffusion coefficient of a nano-colloid suspension. For the first time, correlation times on the submillisecond time scale are accessible with a large-area pixel detector

  7. X-ray source considerations in operation of digital detector arrays

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Terrence; Wendt, Scott [Iowa State University, Center for NDE, 1915 Scholl Road, Ames, IA 50011 (United States)

    2014-02-18

    Digital Detector Arrays (DDA) are increasingly replacing film in radiography applications. Standards exist for characterizing the performance of these detectors, and for using them in specific inspections. We have observed that the selection of the x-ray source to use with these detectors can also have a significant influence on the performance. We look at differences between standard, and micro-focus x-ray tubes, and end-window vs. side-window micro-focus tubes. We find that for best results, one must calibrate the DDA for the source settings used during an inspection. This is particularly true for variable-focus sources.

  8. X-ray source considerations in operation of digital detector arrays

    Science.gov (United States)

    Jensen, Terrence; Wendt, Scott

    2014-02-01

    Digital Detector Arrays (DDA) are increasingly replacing film in radiography applications. Standards exist for characterizing the performance of these detectors, and for using them in specific inspections. We have observed that the selection of the x-ray source to use with these detectors can also have a significant influence on the performance. We look at differences between standard, and micro-focus x-ray tubes, and end-window vs. side-window micro-focus tubes. We find that for best results, one must calibrate the DDA for the source settings used during an inspection. This is particularly true for variable-focus sources.

  9. X-ray computed tomography system utilizing a cadmium telluride detector

    OpenAIRE

    佐藤, 英一; 野宮, 聖一郎; 人見, 啓太朗; 尾鍋, 秀明; 河合, 敏明; 小川, 彰; 佐藤, 成大; 市丸, 俊夫; サトウ, エイイチ; ノミヤ, セイイチロウ; ヒトミ, ケイタロウ; オナベ, ヒデアキ; カワイ, トシアキ; オガワ, アキラ; サトウ, シゲヒロ

    2007-01-01

    A simple x-ray computed tomography(CT) system utilizing a cadmium telluride detector is described. The CT system is of the first generation type and consists of an x-ray generator, a turn table, a translation table, a motor drive unit, a cadmium telluride detector, an interface unit for the detector, and a personal computer(PC). Tomography was performed by the repetition of the translation and rotation of an object. The maximum values of the tube voltage and the tube current were 110kV and 2....

  10. Optical optimization for anti-coincidence detectors of a Hard X-ray Modulation Telescope

    Science.gov (United States)

    Li, Yun-Long; Zhang, Chen; Zhang, Zhao; Fu, Min-Xue; Chen, Yi-Bao; Zhao, Dong-Hua; Deng, Jing-Kang; Shang, Ren-Cheng

    2016-01-01

    The anti-coincidence detectors of Hard X-ray Modulation Telescope (HXMT) are designed to suppress the X-ray background induced by incident charged cosmic-ray particles. The main components of anti-coincidence detectors are thin flat plastic scintillators. In this work we apply the TracePro program to study the light transfer features in the scintillators, and we propose several optimized reflector configurations to significantly improve the light transfer efficiency. The simulation results are verified by measurements of the detector prototypes. We chose a particular optimized reflector configuration.

  11. Characterising a Si(Li) detector element for the SIXA X-ray spectrometer

    CERN Document Server

    Tikkanen, T; Scholze, F; Thornagel, R; Ulm, G

    1997-01-01

    The detection efficiency and response function of a Si(Li) detector element for the SIXA spectrometer have been determined in the 500 eV to 5 keV energy range using synchrotron radiation emitted at a bending magnet of the electron storage ring BESSY, which is a primary radiation standard. The agreement between the measured spectrum and the model calculation is better than 2%. PACS: 95.55.Ka; 07.85.Nc; 29.40.Wk; 85.30.De Keywords: Si(Li) detectors, X-ray spectrometers, detector calibration, X-ray response, spectral lineshape

  12. Near room temperature X-ray and Gamma ray spectroscopic detectors for future space experiments

    OpenAIRE

    Yadav, J.S.; Savitri, S.; Malkar, J. P.

    2005-01-01

    New generation Cadmium Telluride (CZT & CdTe) solid state detectors can provide high quantum efficiency with reasonably good energy resolution and can operate at near room temperature; an unique advantage for space experiments. We present here results of our study of small diode detectors as well as large area pixel detectors. Our study is aimed at developing near room temperature hard X-ray spectroscopy detectors for ASTROSAT and other future Indian space science missions.We have studied a S...

  13. Micro X-ray diffraction using X-ray area detector and identifying multiple phases in Zr2TiAl alloy system

    International Nuclear Information System (INIS)

    The birth of X-ray diffraction technique and its evolution has catalyzed the development of solid state science and further our understanding of material properties. The first single crystal X-ray diffraction pattern recorded was of Copper Sulphate Hydrate on a photographic film by Laue, and his co-workers Friedrich and Knipping, in 1912, for which he was awarded the Nobel prize. The actual diffraction pattern obtained was pretty awful with vague smudges instead of sharp diffraction spots (1). Development of X-ray detection technology has been playing an important role in advancing the development of new X-ray diffraction and imaging techniques. For instance, developments in electronics in the 1960's to 80's enabled advent of point detectors (eg. Nal scintillation detector) and line detectors (e.g gas filled single wire detector). These led to faster and more sensitive detection of X-rays leading to good XRD patterns. However, important information about microstructural details, defects, etc that are manifest well in the two dimensional map of the reciprocal space could be obtained reliably using area detectors (e.g X-ray films) (2). In the 1990's new developments in 2D X-ray area detectors such as Charge coupled devices (CCD), Imaging Plate Systems (IPS) and Multiwire proportional counters (MPC) led to replacement of the slower and low sensitive X-ray films with extremely sensitive 2D detection technology. This presentation will discuss these 2D detection techniques and their underlying mechanism. Recently the structure of multiple phases in Zr2TiAl alloy system could be identified using micro-XRD and 2D detection technique. Result of this study will be presented. (author)

  14. Were most Low Mass X ray Binaries born in Globular Clusters?

    CERN Document Server

    D'Antona, F; Ventura, P; Antona, Francesca D'; Teodorescu, Anamaria; Ventura, Paolo

    2006-01-01

    We summarize the status of art of the secular evolution of low mass X-ray binaries (LMXBs) and take a close look at the orbital period distribution of LMXBs and of binary millisecond pulsars (MSP), in the hypothesis that this latter results from the LMXB evolution. The deficiency of systems below the period gap, which in cataclysmic binaries occurs between ~ 2 and 3 hr, points to a very different secular evolution of LMXBs with respect to their counterparts containing a white dwarf compact object. The presence of several ultrashort period LMXBs (some of which are also X-ray millisecond pulsars), the important fraction of binary MSPs at periods between 0.1 and 1 day, the periods (26 and 32hr) of two ``interacting'' MSPs in Globular Clusters are other pieces of the puzzle in the period distribution. We consider the possible explanations for these peculiarities, and point out that Grindlay's old proposal that all (most of) LMXBs in the field were originally born in globular clusters must be carefully reconsidere...

  15. Adjustment of a low energy, X-rays generator (6 kV - 50 mA). Application to X-rays detectors calibration

    International Nuclear Information System (INIS)

    The aim of this memoir is the calibration of an aluminium photocathode X-rays photoelectric detector, in the spectral range 0,5 keV - 1,5 KeV, with a continuous X-ray source. The detectors's calibration consist to measure the detector's sensitivity versus incident energy. In order to produce monochromatic incident beam on the detector, we used a multilayer mirror whose reflectivity was characterized. The measurements are compared to those realized in an other laboratory. (authors). 36 refs., 61 figs., 13 tabs., 2 photos

  16. Development of a lens-coupled CMOS detector for an X-ray inspection system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ho Kyung [School of Mechanical Engineering, Pusan National University, Jangjeon, Geumjeong, Pusan 609-735 (Korea, Republic of) and Basic Atomic Energy Research Institute, Pusan National University, Pusan 609-735 (Korea, Republic of)]. E-mail: hokyung@pnu.edu; Ahn, Jung Keun [Basic Atomic Energy Research Institute, Pusan National University, Pusan 609-735 (Korea, Republic of); Department of Physics, Pusan National University, Pusan 609-735 (Korea, Republic of); Cho, Gyuseong [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of)

    2005-06-11

    A digital X-ray imaging detector based on a complementary metal-oxide-semiconductor (CMOS) image sensor has been developed for X-ray non-destructive inspection applications. This is a cost-effective solution because of the availability of cheap commercial standard CMOS image sensors. The detector configuration adopts an indirect X-ray detection method by using scintillation material and lens assembly. As a feasibility test of the developed lens-coupled CMOS detector as an X-ray inspection system, we have acquired X-ray projection images under a variety of imaging conditions. The results show that the projected image is reasonably acceptable in typical non-destructive testing (NDT). However, the developed detector may not be appropriate for laminography due to a low light-collection efficiency of lens assembly. In this paper, construction of the lens-coupled CMOS detector and its specifications are described, and the experimental results are presented. Using the analysis of quantum accounting diagram, inefficiency of the lens-coupling method is discussed.

  17. Development of a lens-coupled CMOS detector for an X-ray inspection system

    International Nuclear Information System (INIS)

    A digital X-ray imaging detector based on a complementary metal-oxide-semiconductor (CMOS) image sensor has been developed for X-ray non-destructive inspection applications. This is a cost-effective solution because of the availability of cheap commercial standard CMOS image sensors. The detector configuration adopts an indirect X-ray detection method by using scintillation material and lens assembly. As a feasibility test of the developed lens-coupled CMOS detector as an X-ray inspection system, we have acquired X-ray projection images under a variety of imaging conditions. The results show that the projected image is reasonably acceptable in typical non-destructive testing (NDT). However, the developed detector may not be appropriate for laminography due to a low light-collection efficiency of lens assembly. In this paper, construction of the lens-coupled CMOS detector and its specifications are described, and the experimental results are presented. Using the analysis of quantum accounting diagram, inefficiency of the lens-coupling method is discussed

  18. Development of a lens-coupled CMOS detector for an X-ray inspection system

    Science.gov (United States)

    Kim, Ho Kyung; Ahn, Jung Keun; Cho, Gyuseong

    2005-06-01

    A digital X-ray imaging detector based on a complementary metal-oxide-semiconductor (CMOS) image sensor has been developed for X-ray non-destructive inspection applications. This is a cost-effective solution because of the availability of cheap commercial standard CMOS image sensors. The detector configuration adopts an indirect X-ray detection method by using scintillation material and lens assembly. As a feasibility test of the developed lens-coupled CMOS detector as an X-ray inspection system, we have acquired X-ray projection images under a variety of imaging conditions. The results show that the projected image is reasonably acceptable in typical non-destructive testing (NDT). However, the developed detector may not be appropriate for laminography due to a low light-collection efficiency of lens assembly. In this paper, construction of the lens-coupled CMOS detector and its specifications are described, and the experimental results are presented. Using the analysis of quantum accounting diagram, inefficiency of the lens-coupling method is discussed.

  19. Electrical analysis of a planar-type digital X-ray detector with inert gas

    International Nuclear Information System (INIS)

    Large-area digital X-ray image detectors are currently being investigated for medical diagnostic and non-destructive tests. In this paper, a new planar-type detector for diagnostic X-ray (using an inert gas) imaging is proposed, and its electrical characteristics are presented. Almost gas detectors are designed in the shape of a chamber, so we made a planar-type panel sample based on a plasma display panel (PDP) technique. The transparent electrodes and dielectric layer were formed on the front glass. Additionally, the bottom electrodes and dielectric layer were formed on the rear glass. Then, we injected an inert gas (xenon and helium) with various component ratios into the sample using by gas-filling equipment. We measured the dark current density and the X-ray sensitivity as functions of the electric field to investigate the electrical properties. From the results, a stabilized dark current density and a significant X-ray sensitivity were obtained. Also, the signal linearity was calculated, and a good linearity as a function of exposure dose could be realized over a wide diagnostic energy range. All linearity coefficient γ values were higher than 0.9. These results mean that the passive matrix-addressed flat panel gas detector can be used as a digital x-ray detector.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-01-01

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

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

    Science.gov (United States)

    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. PMID:26698064

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

    DEFF Research Database (Denmark)

    Zavattini, G.; Feroci, M.; Budtz-Jørgensen, Carl; Christensen, Freddy; Frontera, F.; Gambaccini, M.; Ortuno-Prados, F.; Pareschi, G.

    A prototype Xe + 10% CH4 microstrip detector was used to study the K-edge discontinuity in the pulse-height distribution as a function of the energy of incident X-rays. The electronics used was such that a pulse-shape rejection could be made of K-fluorescence reabsorption in the detector. The...

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

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yue, E-mail: ysun@u.northwestern.edu [Graduate Program in Applied Physics, Northwestern University, Evanston, IL 60208 (United States); Gleber, Sophie-Charlotte, E-mail: gleber@aps.anl.gov [Argonne National Laboratory, Argonne, IL 60439 (United States); Jacobsen, Chris, E-mail: cjacobsen@anl.gov [Argonne National Laboratory, Argonne, IL 60439 (United States); Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States); Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208 (United States); Kirz, Janos, E-mail: jkirz@lbl.gov [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Vogt, Stefan, E-mail: vogt@aps.anl.gov [Argonne National Laboratory, Argonne, IL 60439 (United States)

    2015-05-15

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

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

    International Nuclear Information System (INIS)

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

  5. A semiempirical linear model of indirect, flat-panel x-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shih-Ying; Yang Kai; Abbey, Craig K.; Boone, John M. [Department of Biomedical Engineering, University of California, Davis, California, One Shields Avenue, Davis, California 95616 (United States) and Department of Radiology, University of California, Davis, Medical Center, 4860 Y Street, Ambulatory Care Center Suite 0505, Sacramento, California 95817 (United States); Department of Radiology, University of California, Davis, Medical Center, 4860 Y Street, Ambulatory Care Center Suite 0505, Sacramento, California 95817 (United States); Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 92106 (United States); Department of Biomedical Engineering, University of California, Davis, California, One Shields Avenue, Davis, California 95616 (United States) and Department of Radiology, University of California, Davis, Medical Center, 4860 Y Street, Ambulatory Care Center Suite 3100, Sacramento, California 95817 (United States)

    2012-04-15

    Purpose: It is important to understand signal and noise transfer in the indirect, flat-panel x-ray detector when developing and optimizing imaging systems. For optimization where simulating images is necessary, this study introduces a semiempirical model to simulate projection images with user-defined x-ray fluence interaction. Methods: The signal and noise transfer in the indirect, flat-panel x-ray detectors is characterized by statistics consistent with energy-integration of x-ray photons. For an incident x-ray spectrum, x-ray photons are attenuated and absorbed in the x-ray scintillator to produce light photons, which are coupled to photodiodes for signal readout. The signal mean and variance are linearly related to the energy-integrated x-ray spectrum by empirically determined factors. With the known first- and second-order statistics, images can be simulated by incorporating multipixel signal statistics and the modulation transfer function of the imaging system. To estimate the semiempirical input to this model, 500 projection images (using an indirect, flat-panel x-ray detector in the breast CT system) were acquired with 50-100 kilovolt (kV) x-ray spectra filtered with 0.1-mm tin (Sn), 0.2-mm copper (Cu), 1.5-mm aluminum (Al), or 0.05-mm silver (Ag). The signal mean and variance of each detector element and the noise power spectra (NPS) were calculated and incorporated into this model for accuracy. Additionally, the modulation transfer function of the detector system was physically measured and incorporated in the image simulation steps. For validation purposes, simulated and measured projection images of air scans were compared using 40 kV/0.1-mm Sn, 65 kV/0.2-mm Cu, 85 kV/1.5-mm Al, and 95 kV/0.05-mm Ag. Results: The linear relationship between the measured signal statistics and the energy-integrated x-ray spectrum was confirmed and incorporated into the model. The signal mean and variance factors were linearly related to kV for each filter material (r

  6. Quantum efficiency of Si Hybrid CMOS detectors in the soft X-ray band

    Science.gov (United States)

    Prieskorn, Zachary; Bongiorno, Stephen; Burrows, David; Falcone, Abraham; Griffith, Christopher; Nikoleyczik, Jonathan; Wells, Mark; PSU X-ray Instrumentation Group Team

    2015-04-01

    X-ray sensitive Si Hybrid CMOS detectors (HCDs) will potentially replace X-ray CCDs in the focal planes of future X-ray observatories. HCDs improve on the performance of CCDs in numerous areas: faster read out time, windowed read out mode, less susceptibility to radiation & micrometeoroid damage, and lower power consumption. Understanding the detector quantum efficiency (QE) is critical for estimating the sensitivity of an X-ray instrument. We report on the QE for multiple energies in the soft X-ray band of four HCDs based on the Teledyne Imaging Sensors HyViSITM detectors. These detectors have Al optical blocking filters deposited directly on the Si substrate; these filters vary in thickness from 180 - 1000 Å. We estimate the QE with a 1D slab absorption model and find good agreement between the model and our results across an energy range from 0.677 - 8.05 keV. This work was supported by NASA Grants NNG05WC10G, NNX08AI64G, and NNX11AF98G.

  7. Use of active-edge silicon detectors as X-ray beam monitors

    International Nuclear Information System (INIS)

    Silicon detectors have been developed which are active to within several microns of the physical edge of the detector. These active-edge devices can be placed near an intense X-ray beam to accurately measure the X-ray beam properties. In addition, they can be fabricated in a variety of geometries that will be useful for monitoring the intensity, profile, and position of synchrotron X-ray beams. One shape is a detector with a through hole surrounded by four active elements. The hole allows the intense X-ray beam to go through the center while the four elements can detect any change in the position or dispersion of the beam. Another shape is a rectangular 5 mm longx0.5 mm wide device with a set of four elements that are 100 μm wide. These devices could be mounted on the upstream side of the jaws of an x-y collimating slit to measure the intensity profile of the beam that each jaw of the slit is stopping. Small detectors could also be mounted in a cylindrical beam stop to give on-line beam intensity measurements. A variety of different geometries were tested at beamline 10.3.1 of the Advanced Light Source using a 12.5 keV X-ray beam. They have wide dynamic range, excellent position sensitivity and low sensitivity to radiation damage

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

    CERN Document Server

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

    1999-01-01

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

  9. Use of Gas Electron Multiplier (GEM) Detectors for an Advanced X-ray Monitor

    CERN Document Server

    Remillard, R A; Boughan, E A; Bradt, H V; Morgan, E H; Becker, U J; Nenonen, S; Vilhu, O R

    2000-01-01

    We describe a concept for a NASA SMEX Mission in which Gas Electron Multiplier (GEM) detectors, developed at CERN, are adapted for use in X-ray astronomy. These detectors can be used to obtain moderately large detector area and two-dimensional photon positions with sub mm accuracy in the range of 1.5 to 15 keV. We describe an application of GEMs with xenon gas, coded mask cameras, and simple circuits for measuring event positions and for anticoincidence rejection of particle events. The cameras are arranged to cover most of the celestial sphere, providing high sensitivity and throughput for a wide variety of cosmic explosions. At longer timescales, persistent X-ray sources would be monitored with unprecedented levels of coverage. The sensitivity to faint X-ray sources on a one-day timescale would be improved by a factor of 6 over the capability of the RXTE All Sky Monitor.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-09-11

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

  11. Spectroscopic X-ray imaging with photon counting pixel detectors

    CERN Document Server

    Tlustos, L

    2010-01-01

    Single particle counting hybrid pixel detectors simultaneously provide low noise, high granularity and high readout speed and make it possible to build detector systems offering high spatial resolution paired with good energy resolution. A limiting factor for the spectroscopic performance of such detector systems is charge sharing between neighbouring pixels in the sensor part of the detector. The signal spectrum at the collection electrodes of the readout electronics deviates significantly from the photonic spectrum when planar segmented sensor geometries are used. The Medipix3 implements a novel, distributed signal processing architecture linking neighbouring pixels and aims at eliminating the spectral distortion produced in the sensor by charge sharing and at reducing the impact of fluorescence photons generated in the sensor itself. Preliminary results from the very first Medipix3 readouts bump bonded to 300 pm Si sensor are presented. Material reconstruction is a possible future application of spectrosco...

  12. Mechanism of the high X-ray sensitivity of single-crystal CdTe detectors

    International Nuclear Information System (INIS)

    One investigated into the effect of germanium amorphous impurities on X-ray sensitivity and on other features of single-crystals. One investigated into CdTe heat-stable crystals. One proposes a model of a local rearrangement of crystalline lattice near GeCd impurity atom. High X-ray sensitivity of CdTe doped by Ge impurity (doping levels = 3.0x1015 cm-3) is explained by difference of mobility of electrons and holes under ambipolar X-ray conductivity. The optimal impurity-defect composition of p-CdTe crystals serving as high-sensitive active elements of X-ray detectors is characterized by presence of GeCd, VCd defects and of VTe-Tei Frenkel pairs

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-01

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

  14. Fast response amplitude scintillation detector for X-ray synchrotron radiation

    International Nuclear Information System (INIS)

    The present paper describes a scintillation detector for X-ray synchrotron radiation. This detector has been created on the basis of a scintillator and a photoelectron multiplier (FEU-130) and its construction allows one to use the specific features of the time characteristics of synchrotron radiation from the electron storage ring. In a given range of amplitudes, the detector electronics makes a 64-channel amplitude analysis of the FEU-130 signal strobed by the revolution frequency of an electron bunch in the storage ring (f0 = 818 kHz). There is the possibility of operating the detector at high intensities of the monochromatic radiation incident on the scintillator. Such a possibility is directly provided by the time structure of SR and is not realizable with the use of other X-ray sources. The detector will find wide application in studies on X-ray structural analysis, transmission and fluorescent EXAFS- and XANES-spectroscopy, transmission scanning microscopy and microtomography, calibration of X-ray detectors and as a monitor on SR beams from the storage ring VEPP-4. (orig.)

  15. Plastic nuclear track detectors as high x-ray and gamma dosimeters

    International Nuclear Information System (INIS)

    A brief review of recent studies on the effects of high doses of x-ray and gamma ray on the track registration properties of several plastic track detectors is presented. The bulk etching rates and the etched track sizes have been found to increase with the dose in the range up to 100 Mrad. These results suggest that the changes in track registration characteristics can be employed as an index of the radiation dose in the megarad region. In particular, recent results on the effect of X-ray irradiation on two types of cellulose nitrate track detectors obtained in our laboratory are reported in this paper. (author)

  16. 20 element HgI sub 2 energy dispersive x-ray array detector system

    Energy Technology Data Exchange (ETDEWEB)

    Iwanczyk, J.A.; Dorri, N.; Wang, M.; Szczebiot, R.W.; Dabrowski, A.J. (Xsirius, Inc., Marina Del Rey, CA (United States)); Hedman, B.; Hodgson, K.O. (Stanford Univ., CA (United States). Stanford Synchrotron Radiation Lab.); Patt, B.E. (EG and G Energy Measurements, Inc., Goleta, CA (United States))

    1991-01-01

    This paper describes recent progress in the development of HgI{sub 2} energy dispersive x-ray detector arrays and associated miniaturized processing electronics for synchrotron radiation research applications. The experimental results with a 20 element array detector were obtained under realistic synchrotron beam conditions at SSRL. An energy resolution of 250 eV (FWHM) at 5.9 keV (Mn-K{sub a}) was achieved. Energy resolution and throughput measurements versus input count rate and energy of incoming radiation have been measured. Extended X-ray Absorption Fine Structure (EXAFS) spectra were taken from diluted samples simulating proteins with nickel.

  17. 20 element HgI{sub 2} energy dispersive x-ray array detector system

    Energy Technology Data Exchange (ETDEWEB)

    Iwanczyk, J.A.; Dorri, N.; Wang, M.; Szczebiot, R.W.; Dabrowski, A.J. [Xsirius, Inc., Marina Del Rey, CA (United States); Hedman, B.; Hodgson, K.O. [Stanford Univ., CA (United States). Stanford Synchrotron Radiation Lab.; Patt, B.E. [EG and G Energy Measurements, Inc., Goleta, CA (United States)

    1991-12-31

    This paper describes recent progress in the development of HgI{sub 2} energy dispersive x-ray detector arrays and associated miniaturized processing electronics for synchrotron radiation research applications. The experimental results with a 20 element array detector were obtained under realistic synchrotron beam conditions at SSRL. An energy resolution of 250 eV (FWHM) at 5.9 keV (Mn-K{sub a}) was achieved. Energy resolution and throughput measurements versus input count rate and energy of incoming radiation have been measured. Extended X-ray Absorption Fine Structure (EXAFS) spectra were taken from diluted samples simulating proteins with nickel.

  18. 20 element HgI2 energy dispersive x-ray array detector system

    International Nuclear Information System (INIS)

    This paper describes recent progress in the development of HgI2 energy dispersive x-ray detector arrays and associated miniaturized processing electronics for synchrotron radiation research applications. The experimental results with a 20 element array detector were obtained under realistic synchrotron beam conditions at SSRL. An energy resolution of 250 eV (FWHM) at 5.9 keV (Mn-Ka) was achieved. Energy resolution and throughput measurements versus input count rate and energy of incoming radiation have been measured. Extended X-ray Absorption Fine Structure (EXAFS) spectra were taken from diluted samples simulating proteins with nickel

  19. The 20 element HgI2 energy dispersive x ray array detector system

    Science.gov (United States)

    Iwanczyk, J. A.; Dorri, N.; Wang, M.; Szczebiot, R. W.; Dabrowski, A. J.; Hedman, B.; Hodgson, K. O.; Patt, B. E.

    1991-11-01

    This paper describes recent progress in the development of HgI2 energy dispersive x-ray detector arrays and associated miniaturized processing electronics for synchrotron radiation research applications. The experimental results with a 20 element array detector were obtained under realistic synchrotron beam conditions at SSRL. An energy resolution of 250 eV (FWHM) at 5.9 keV (Mn-K(sub a)) was achieved. Energy resolution and throughput measurements versus input count rate and energy of incoming radiation have been measured. Extended X-ray Absorption Fine Structure (EXAFS) spectra were taken from diluted samples simulating proteins with nickel.

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

    Science.gov (United States)

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

    2015-04-01

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

  1. Three dimensional digital X-ray microtomography with a microfocal X-ray generator and an MWPC area detector

    International Nuclear Information System (INIS)

    X-ray microscopy offers many potential applications in the life sciences and non-destructive testing for the study of small (micron-sized) structures. Digital capture of the X-ray images offers further possibilities for image processing and for tomography. We have combined a microfocal X-ray generator with a multi-step avalanche/multiwire proportional counter to produce a digital X-ray microscope. Spatial resolution down to around 10 microns has been observed. The digital data sets obtained from the system have been used to develop and explore 3-D tomographic images of an insect are presented, produced by a cone beam algorithm. (author)

  2. Compton polarimetry with position-resolving X-ray detectors

    International Nuclear Information System (INIS)

    In the present thesis the prototype of a novel position-resolving and multi-hit able 2D Si(Li) strip detector is characterized, the planar detector crystal of which is simultaneously applied both as scatterer and as absorber. In the framework of this thesis the Si(Li) polarimeter could be applied in different experiments on the radiative electron capture and on the characteristic radiation at the experimental storage ring of the GSI. The characterization of the detector pursued by means of the highly polarized radiation of the electron capture into the K shell of naked xenon. In the following in two further experiments new values on the polarization of the electron capture into the K shell both of the naked and of the hydrogen-like uranium were performed.

  3. X-Ray and Gamma-Ray Radiation Detector

    DEFF Research Database (Denmark)

    2015-01-01

    (P) along a first axis, a plurality of drift electrodes, a readout circuitry being configured to read out signals from the plurality of detector electrodes and a processing unit connected to the readout circuitry and being configured to detect an event in the converter element. The readout circuitry...... is further configured to read out signals from the plurality of drift electrodes, and the processing unit is further configured to estimate a location of the event along the first axis by processing signals obtained from both the detector electrodes and the drift electrodes, the location of the event along...

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

    Science.gov (United States)

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

    2015-03-01

    The energy information acquired using spectral X-ray detectors allows noninvasive identification and characterization of chemical components of a material. To achieve this, it is important that the energy response of the detector is calibrated. The established techniques for energy calibration are not practical for routine use in pre-clinical or clinical research environment. This is due to the requirements of using monochromatic radiation sources such as synchrotron, radio-isotopes, and prohibitively long time needed to set up the equipment and make measurements. To address these limitations, we have developed an automated technique for calibrating the energy response of the pixels in a spectral X-ray detector that runs with minimal user intervention. This technique uses the X-ray tube voltage (kVp) as a reference energy, which is stepped through an energy range of interest. This technique locates the energy threshold where a pixel transitions from not-counting (off) to counting (on). Similarly, we have developed a technique for calibrating the energy response of individual pixels using X-ray fluorescence generated by metallic targets directly irradiated with polychromatic X-rays, and additionally γ-rays from (241)Am. This technique was used to measure the energy response of individual pixels in CdTe-Medipix3RX by characterizing noise performance, threshold dispersion, gain variation and spectral resolution. The comparison of these two techniques shows the energy difference of 1 keV at 59.5 keV which is less than the spectral resolution of the detector (full-width at half-maximum of 8 keV at 59.5 keV). Both techniques can be used as quality control tools in a pre-clinical multi-energy CT scanner using spectral X-ray detectors. PMID:25051546

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

    CERN Document Server

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

    2002-01-01

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

  6. The effect of x-ray summing in calibration of extended energy range GE detectors

    Energy Technology Data Exchange (ETDEWEB)

    Klemola, S. [STUK - Radiation and Nuclear Safety Authority, Helsinki (Finland)

    2002-04-01

    Gamma spectrometric analyses of low-level samples are usually performed using close measuring geometry. In this measuring set-up the effect of the true coincidence summing (TCS) has to be taken into account. The detection of true coincidence sum pulse is possible when a nuclide emits two or more cascading photons within the resolving time of a spectrometer. The magnitude of summing depends strongly on the total and full energy peak efficiencies of the detector and on the decay scheme of the nuclide. In addition to summing of gamma rays, other radiation, especially X-rays, can be in true coincidence with the gamma rays. X-rays in cascade with gamma rays can originate from electron capture, positron decay, or internal conversion. The summing effects with most of the X-rays can be ignored for the p-type Ge detectors having thick dead layer. On the contrary, the detectors with a thin entrance window, e.g. n-type detectors and new extended range p-type detectors, can experience severe summing of X-rays and gamma rays. (au)

  7. The effect of x-ray summing in calibration of extended energy range GE detectors

    International Nuclear Information System (INIS)

    Gamma spectrometric analyses of low-level samples are usually performed using close measuring geometry. In this measuring set-up the effect of the true coincidence summing (TCS) has to be taken into account. The detection of true coincidence sum pulse is possible when a nuclide emits two or more cascading photons within the resolving time of a spectrometer. The magnitude of summing depends strongly on the total and full energy peak efficiencies of the detector and on the decay scheme of the nuclide. In addition to summing of gamma rays, other radiation, especially X-rays, can be in true coincidence with the gamma rays. X-rays in cascade with gamma rays can originate from electron capture, positron decay, or internal conversion. The summing effects with most of the X-rays can be ignored for the p-type Ge detectors having thick dead layer. On the contrary, the detectors with a thin entrance window, e.g. n-type detectors and new extended range p-type detectors, can experience severe summing of X-rays and gamma rays. (au)

  8. A micro-strip germanium detector for position sensitive X-ray spectroscopy

    International Nuclear Information System (INIS)

    For the current X-ray spectroscopy program at the ESR storage ring (GSI-Darmstadt) a position sensitive germanium detector system has been completed. The position sensitive structure of the detector has been realized on an area of 47 mm x 23.4 mm by an array of 200 strips (200 μm wide and 23.4 mm long) separated by 35 μm wide grooves etched through boron implanted contact. The thickness of the detector inclusive a 0.6 mm thick Li-diffused rear contact amounts to 4.1 mm. Each strip has been joined to a preamplifier placed outside the cryostat with printed leads inside the flexible Kapton foil. The energy resolution of the strips has been about 1.8 keV [FWHM] for 60 keV photons. Coincidences between neighbouring strips were measured whereby a time resolution of 70 ns [FWHM] was obtained. First preliminary results obtained with the detector mounted at the transmission X-ray spectrometer FOCAL demonstrated that an energy resolution better than 100 eV is achievable together with a high detection efficiency. Along with a new kind of X-ray spectrometer this detector may play a keyrole for the next step of high precision X-ray experiments, aiming on a precise test of quantum electrodynamics in the heaviest one-electron systems such as hydrogenlike uranium. (orig.)

  9. Effects of nuclear fusion produced neutrons on silicon semiconductor plasma X-ray detectors

    CERN Document Server

    Kohagura, J; Hirata, M; Numakura, T; Minami, R; Watanabe, H; Sasuga, T; Nishizawa, Y; Yoshida, M; Nagashima, S; Tamano, T; Yatsu, K; Miyoshi, S; Hirano, K; Maezawa, H

    2002-01-01

    The effects of nuclear fusion produced neutrons on the X-ray energy responses of semiconductor detectors are characterized. The degradation of the response of position-sensitive X-ray tomography detectors in the Joint European Torus (JET) tokamak is found after neutron exposure produced by deuterium-deuterium and deuterium-tritium plasma fusion experiments. For the purpose of further detailed characterization of the neutron degradation effects, an azimuthally varying-field (AVF) cyclotron accelerator is employed using well-calibrated neutron fluence. These neutron effects on the detector responses are characterized using synchrotron radiation from a 2.5 GeV positron storage ring at the Photon Factory (KEK). The effects of neutrons on X-ray sensitive semiconductor depletion thicknesses are also investigated using an impedance analyser. Novel findings of (i) the dependence of the response degradation on X-ray energies as well as (ii) the recovery of the degraded detector response due to the detector bias applic...

  10. An InGrid based Low Energy X-ray Detector

    CERN Document Server

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

    2014-01-01

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

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

    CERN Document Server

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

    2007-01-01

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

  12. Optical characterisation of lithium fluoride detectors for broadband X-ray imaging

    International Nuclear Information System (INIS)

    Novel X-ray imaging detectors based on photoluminescence of colour centres in lithium fluoride (LiF) have been proposed and tested for extreme ultraviolet, soft and hard X-rays up to 10 keV. For the first time we present the optical characterisation of LiF crystals and thin films irradiated at the TOPO–TOMO beamline of synchroton light source Anka (Karlsruhe, Germany) in the energy range 6–40 keV for different exposure times. Absorption and photoluminescence spectra were analysed to study the optical response of the LiF-based detectors. High resolved X-ray imaging of commercial test patterns has been obtained on LiF crystals and films by optical readout with a confocal laser scanning fluorescence microscope

  13. Superconducting Al-trilayer tunnel junctions for use as X-ray detectors

    Science.gov (United States)

    Gaidis, M. C.; Friedrich, S.; Prober, D. E.; Moseley, S. H.; Szymkowiak, A. E.

    1993-01-01

    Photolithographic techniques have been developed to fabricate high-quality Al-Al oxide-Al superconducting tunnel junctions for use in X-ray detectors. These devices are designed to incorporate about 1-micron-thick superconducting X-ray absorbers for the detection of less than 10-keV single photons. In an effort to increase energy resolution, superconductor bandgap engineering with lateral and vertical trapping has been used to shorten quasi-particle tunneling times and diffusion lengths and to prevent quasi-particle diffusion away from the tunnel junction. Methods that have been developed for overcoming materials imcompatibility and device degradation upon thermal cycling are reported. The authors also report on the use of a nonrectangular tunnel junction geometry which reduces the magnetic field needed to suppress the Josephson current for stable biasing. Work in progress to measure the energy resolution of these X-ray detectors at 0.35 K is also discussed.

  14. Performance of low-cost X-ray area detectors with consumer digital cameras

    International Nuclear Information System (INIS)

    We constructed X-ray detectors using consumer-grade digital cameras coupled to commercial X-ray phosphors. Several detector configurations were tested against the Varian PaxScan 3024M (Varian 3024M) digital flat panel detector. These include consumer cameras (Nikon D800, Nikon D700, and Nikon D3X) coupled to a green emission phosphor in a back-lit, normal incidence geometry, and in a front-lit, oblique incidence geometry. We used the photon transfer method to evaluate detector sensitivity and dark noise, and the edge test method to evaluate their spatial resolution. The essential specifications provided by our evaluation include discrete charge events captured per mm2 per unit exposure surface dose, dark noise in equivalents of charge events per pixel, and spatial resolution in terms of the full width at half maximum (FWHM) of the detector's line spread function (LSF). Measurements were performed using a tungsten anode X-ray tube at 50 kVp. The results show that the home-built detectors provide better sensitivity and lower noise than the commercial flat panel detector, and some have better spatial resolution. The trade-off is substantially smaller imaging areas. Given their much lower costs, these home-built detectors are attractive options for prototype development of low-dose imaging applications

  15. Radiation damage effects on X-ray silicon detectors

    International Nuclear Information System (INIS)

    The paper describes some results concerning technology and behaviour of X-and gamma-ray n+pp+ silicon detectors used in physics research, industrial and medical radiography and non-destructive testing. These detectors work at the room-temperature and can be used individually to detect X-and soft gamma-rays, or coupled with scintillators for higher incoming energies. Electrical characteristics of these photodiodes, their modification after exposure to radiation and results of spectroscopic X-and gamma-ray measurements are discussed. Devices manufactured under this technology proved to be stable after an exposure in high intensity gamma field with the dose range of 10 Krad-5 Mrad. Nuclear radiation resistance was studied by irradiation with 60 Co gamma source (1.17 and 1.33 MeV) at dose rates of 59 Krad/hour and 570 Krad/hour. Results indicate that proposed structures enable the development of reliable silicon detectors to be used in a high gamma-radiation environments encountered in a lot of applications. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

    Kimmel, Nils

    2009-02-12

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

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

    International Nuclear Information System (INIS)

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

  18. Development of edgeless TSV X-ray detectors

    Science.gov (United States)

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

    2016-02-01

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

  19. Indium phosphide X-Ray and particle detector

    Czech Academy of Sciences Publication Activity Database

    Pekárek, Ladislav; Žďánský, Karel

    Bratislava: Slovak University of Technology in Bratislava, 2006 - (Nitsch, K.; Rodová, M.), s. 52-53 ISBN 80-901-748-7-6. [Development of Materials Science in Research and Education , Joint Seminar 2006 /16./. Valtice (CZ), 12.09.2006-15.09.2006] R&D Projects: GA ČR(CZ) GA102/06/0153; GA AV ČR(CZ) KAN400670651 Institutional research plan: CEZ:AV0Z20670512; CEZ:AV0Z10100520 Keywords : particle detectors * III-V semiconductors * crystal growth Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  20. Experimental study of a single-pixel prototype anti-scatter detector for megavoltage x-ray imaging

    Science.gov (United States)

    Tian, Y.; Pang, G.

    2016-02-01

    Scattered x rays are detrimental to the image quality of x-ray transmission radiography. Anti-scatter grids have been used in diagnostic x-ray imaging to improve the image quality but are not practical to use for megavoltage (MV) x-ray imaging in radiotherapy since a MV grid would be very bulky, heavy, and costly. An inherent anti-scatter detector based on Čerenkov radiation was introduced recently for MV x-ray imaging. The purpose of this work is to investigate experimentally the anti-scatter property of a single pixel prototype detector. The scatter to primary ratio (SPR) has been measured using a linear accelerator with a 6 MV x-ray beam. It has been found that the SPR for the prototype detector is 30-60% less than that of an ionization chamber, depending on the imaging geometry. This indicates the prototype detector is less sensitive to scattered radiation.

  1. Pixel array detector for time-resolved x-ray scattering

    International Nuclear Information System (INIS)

    This paper describes the development of a large area hybrid pixel detector designed for time-resolved synchrotron x-ray scattering experiments in which limited frames, with a high framing rate, are required. The final design parameters call for a 1024x1024 pixel array device with 150-micron pixels that is 100% quantum efficient for x-rays with energy up to 20 keV, with a framing rate in the microsecond range. The device will consist of a fully depleted diode array bump bonded to a CMOS electronic storage capacitor array with eight frames per pixel. The two devices may be separated by a x-ray blocking layer that protects the radiation-sensitive electronics layer from damage. The signal is integrated in the electronics layer and stored in one of eight CMOS capacitors. After eight frames are taken, the data are then read out, using clocking electronics external to the detector, and stored in a RAM disk. Results will be presented on the development of a prototype 4x4 pixel electronics layer that is capable of storing at least 10,000 12-keV x-ray photons for a capacity of over 50 million electrons with a noise corresponding to 2 x-ray photons per pixel. The diode detective layer and electronics storage layer along with the radiation damage and blocking layers will be discussed. copyright 1996 American Institute of Physics

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

    Science.gov (United States)

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

    2016-05-01

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

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

    CERN Document Server

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

    2008-01-01

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

  4. CdZnTe detector for combined X-ray CT and SPECT

    International Nuclear Information System (INIS)

    A medical imaging system providing both X-ray transmission and radionuclide measurements would allow correlation of structural and functional information. We therefore are evaluating a pixellated CdZnTe detector for combined X-ray computed tomography (CT) and single photon emission computed tomography (SPECT) imaging. Gamma-ray spectra of 57Co measured using NIM electronics (2 μs shaping time) and multichannel fast photon-counting electronics (50 ns shaping time) produced energy resolutions of 6.5 keV FWHM and 17 keV FWHM, respectively, at 122 keV. Fast photon-counting electronics achieved linear X-ray count-rate response up to 4x105 cps in comparison to 1.5x108 cps achieved with digital readout electronics based on a variable rate ΣΔ ADC in current mode. Results suggest that the CdZnTe detector is capable of performing both X-ray CT and SPECT with the fast photon-counting electronics, and X-ray CT in current mode with the digital readout electronics

  5. The detection of soft X-rays with charged coupled detectors

    International Nuclear Information System (INIS)

    The characteristics of an ideal soft X-ray imaging detector are enumerated. Of recent technical developments the CCD or charge coupled device goes furthest to meeting these requirements. Several properties of CCDs are described with reference to experimental work and their application to practical instruments is reviewed

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

    OpenAIRE

    Inoue, Yoshizumi; Moriyama, Shigetaka; Hara, Hideyuki; Minowa, Makoto; Shimokoshi, Fumio

    1995-01-01

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

  7. Temporal evolution of impurity profile measured by a soft x-ray detector array on LHD

    International Nuclear Information System (INIS)

    A stable method to reconstruct the soft X-ray (SX) emissivity profile is described in detail from the measurements of the SX detector array system on the Large Helical System (LHD). Sudden peaking of the SX emissivity profile after hydrogen ice-pellet injection is discussed, as an interesting application of this reconstruction method. (author)

  8. The X-ray mirror telescope and the pn-CCD detector of CAST

    CERN Document Server

    Kuster, M; Englhauser, J; Franz, J; Friedrich, P; Hartmann, R; Kang, D; Kotthaus, R; Lutz, Gerhard; Moralez, J; Serber, W; Strüder, L

    2004-01-01

    The Cern Axion Solar Telescope - CAST - uses a prototype 9 Tesla LHC superconducting dipole magnet to search for a hypothetical pseudoscalar particle, the axion, which was proposed by theory in the 1980s to solve the strong CP problem and which could be a dark matter candidate. In CAST a strong magnetic field is used to convert the solar axions to detectable photons via inverse Primakoff effect. The resulting X-rays are thermally distributed in the energy range of 1-7 keV and can be observed with conventional X-ray detectors. The most sensitive detector system of CAST is a pn-CCD detector originally developed for XMM-Newton combined with a Wolter I type X-ray mirror system. The combination of a focusing X-ray optics and a state of the art pn-CCD detector which combines high quantum efficiency, good spacial and energy resolution, and low background improves the sensitivity of the CAST experiment such that for the first time the axion photon coupling constant can be probed beyond the best astrophysical constrai...

  9. Properties and applications of photon counting and energy resolved X-ray matrix detectors

    International Nuclear Information System (INIS)

    The use of highly absorbing photoconductor materials (e.g. CdTe) for the production of matrix X-ray detectors allows for a number of years, the direct conversion of X-rays into evaluable electrical signals, for the NDT energy to 300 keV too. The conventional scintillator is omitted, resulting in a reduction of image blurring and an increase in efficiency due to the much larger absorption thicknesses result. Also can be at a sufficiently fast readout speed (50 - 100 ns dead time) count single photons and determine their energy. Thus, the readout noise and the dark image correction omitted. Furthermore, one can detect or hide selectively certain areas of the X-ray energy spectrum by defining energy threshold values. This feature allows one the one hand, the discrimination of materials through the dual energy technology and on the other hand, the reduction of the detected scattered radiation, thereby increasing the contrast sensitivity. In order to use these advantages efficiently, a special calibration procedure is required, which must take into account time-dependent processes in the detector layer. Presented here are the properties of this new generation of X-ray detectors matrix compared to traditional indirect converting detectors based on reference measurements on fiber composite components and thick-walled steel tubes (up to 35 mm). Further possible applications in NDT are discussed with regard to the material discrimination especially within fiber composites (eg CFRP and GFRP).(Contains PowerPoint slides).

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

    Science.gov (United States)

    Marcovici, Sorin; Sukhovatkin, Vlad; Oakham, Peter

    2014-03-01

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

  11. X-ray and gamma ray detector readout system

    Science.gov (United States)

    Tumer, Tumay O; Clajus, Martin; Visser, Gerard

    2010-10-19

    A readout electronics scheme is under development for high resolution, compact PET (positron emission tomography) imagers based on LSO (lutetium ortho-oxysilicate, Lu.sub.2SiO.sub.5) scintillator and avalanche photodiode (APD) arrays. The key is to obtain sufficient timing and energy resolution at a low power level, less than about 30 mW per channel, including all required functions. To this end, a simple leading edge level crossing discriminator is used, in combination with a transimpedance preamplifier. The APD used has a gain of order 1,000, and an output noise current of several pA/ Hz, allowing bipolar technology to be used instead of CMOS, for increased speed and power efficiency. A prototype of the preamplifier and discriminator has been constructed, achieving timing resolution of 1.5 ns FWHM, 2.7 ns full width at one tenth maximum, relative to an LSO/PMT detector, and an energy resolution of 13.6% FWHM at 511 keV, while operating at a power level of 22 mW per channel. Work is in progress towards integration of this preamplifier and discriminator with appropriate coincidence logic and amplitude measurement circuits in an ASIC suitable for a high resolution compact PET instrument. The detector system and/or ASIC can also be used for many other applications for medical to industrial imaging.

  12. Development of edgeless TSV X-ray detectors

    International Nuclear Information System (INIS)

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

  13. Use of multielement detector systems with synchrotron x-ray sources

    International Nuclear Information System (INIS)

    The extremely high intensity and pulsed structure of synchrotron radiation x-ray sources put very demanding requirements on associated x-ray detectors. In current detector systems, trade-offs must be made between the efficiency, energy resolution, counting rate capability and the spatial resolution. Two detector systems are described which illustrate the optimization of these parameters for different applications of synchrotron radiation. One system is a segmented 16 channel multiwire proportional chamber which is used for fluorescent EXAFS measurements. The other is a 30 element Si(Li) linear detector array which is used for digital angiography experiments. The characteristics of these systems are discussed and recent results obtained with them are presented

  14. Automatic analysis of quality of images from X-ray digital flat detectors

    International Nuclear Information System (INIS)

    Since last decade, medical imaging has grown up with the development of new digital imaging techniques. In the field of X-ray radiography, new detectors replace progressively older techniques, based on film or x-ray intensifiers. These digital detectors offer a higher sensibility and reduced overall dimensions. This work has been prepared with Trixell, the world leading company in flat detectors for medical radiography. It deals with quality control on digital images stemming from these detectors. High quality standards of medical imaging impose a close analysis of the defects that can appear on the images. This work describes a complete process for quality analysis of such images. A particular focus is given on the detection task of the defects, thanks to methods well adapted to our context of spatially correlated defects in noise background. (author)

  15. High-resolution synchrotron X-ray powder diffraction with a linear position-sensitive detector

    International Nuclear Information System (INIS)

    X-ray synchrotron powder data were collected from a capillary sample of a small-molecule organic peptide compound, glycylglycine (NH2CH2CONHCH2-COOH) by step-scanning at 10 intervals with a linear position-sensitive detector covering an angular range of 2.70 in order to test the feasibility of recording a high-resolution pattern and using the data for Rietveld analysis. Appropriate corrections for detector linearity and position were implemented, and comparison with a diagram recorded with a single scintillation detector and a crystal analyser system showed similar quality for the two sets of data. A detailed comparison of the refined atomic coordinates and those of an earlier X-ray single-crystal study showed the estimated standard deviations to be significantly underestimated in both refinements. A linear detector should be particularly useful for small samples and capillary specimens of moderately absorbing materials. (orig.)

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

    CERN Document Server

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

    2008-01-01

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

  17. A high rate, low noise, x-ray silicon strip detector system

    International Nuclear Information System (INIS)

    An x-ray detector system, based on a silicon strip detector wire-bonded to a low noise charge-senstive amplifier integrated circuit, has been developed for synchrotron radiation experiments which require very high count rates and good energy resolution. Noise measurements and x-ray spectra were taken using a 6 mm long, 55 μm pitch strip detector in conjunction with a prototype 16-channel charge-sensitive preamplifier, both fabricated using standard 1.2 μm CMOS technology. The detector system currently achieves an energy resolution of 350 eV FWHM at 5.9 key, 2 μs peaking time, when cooled to -5 degree C

  18. A high rate, low noise, x-ray silicon strip detector system

    International Nuclear Information System (INIS)

    An x-ray detector system, based on a silicon strip detector wire-bonded to a low noise charge-sensitive amplifier integrated circuit, has been developed for synchrotron radiation experiments which require very high count rates and good energy resolution. Noise measurements and x-ray spectra were taken using a 6 mm long, 55 μm pitch strip detector in conjunction with a prototype 16-channel charge-sensitive preamplifier, both fabricated using standard 1.2 μm CMOS technology. The detector system currently achieves an energy resolution of 350 eV FWHM at 5.9 keV, 2μs peaking time, when cooled to -5 C

  19. 320x240 GaAs pixel detectors with improved X-ray imaging quality

    Energy Technology Data Exchange (ETDEWEB)

    Irsigler, R.; Andersson, J.; Alverbro, J.; Fakoor-Biniaz, Z.; Froejdh, C.; Helander, P.; Martijn, H.; Meikle, D.; Oestlund, M.; O' Shea, V.; Smith, K

    2001-03-11

    We report on gain and offset corrections for GaAs X-ray pixel detectors, which were hybridised to silicon CMOS readout integrated circuits (ROICs). The whole detector array contains 320x240 square-shaped pixels with a pitch of 38 {mu}m. The GaAs pixel detectors are based on semi-insulating and VPE grown substrates. The ROIC operates in the charge integration mode and provides snapshot as well as real time video images. Previously we have reported that the image quality of semi-insulating GaAs pixel detectors suffer from local variations in X-ray sensitivity. We have now developed a method to compensate for the sensitivity variations by applying suitable offset and gain corrections. The improvement in image quality is demonstrated in the measured signal-to-noise ratio of flood exposure images.

  20. 320x240 GaAs pixel detectors with improved X-ray imaging quality

    International Nuclear Information System (INIS)

    We report on gain and offset corrections for GaAs X-ray pixel detectors, which were hybridised to silicon CMOS readout integrated circuits (ROICs). The whole detector array contains 320x240 square-shaped pixels with a pitch of 38 μm. The GaAs pixel detectors are based on semi-insulating and VPE grown substrates. The ROIC operates in the charge integration mode and provides snapshot as well as real time video images. Previously we have reported that the image quality of semi-insulating GaAs pixel detectors suffer from local variations in X-ray sensitivity. We have now developed a method to compensate for the sensitivity variations by applying suitable offset and gain corrections. The improvement in image quality is demonstrated in the measured signal-to-noise ratio of flood exposure images

  1. The design and flight performance of the PoGOLite Pathfinder balloon-borne hard X-ray polarimeter

    Science.gov (United States)

    Chauvin, M.; Florén, H.-G.; Jackson, M.; Kamae, T.; Kawano, T.; Kiss, M.; Kole, M.; Mikhalev, V.; Moretti, E.; Olofsson, G.; Rydström, S.; Takahashi, H.; Lind, J.; Strömberg, J.-E.; Welin, O.; Iyudin, A.; Shifrin, D.; Pearce, M.

    2016-02-01

    In the 50 years since the advent of X-ray astronomy there have been many scientific advances due to the development of new experimental techniques for detecting and characterising X-rays. Observations of X-ray polarisation have, however, not undergone a similar development. This is a shortcoming since a plethora of open questions related to the nature of X-ray sources could be resolved through measurements of the linear polarisation of emitted X-rays. The PoGOLite Pathfinder is a balloon-borne hard X-ray polarimeter operating in the 25-240 keV energy band from a stabilised observation platform. Polarisation is determined using coincident energy deposits in a segmented array of plastic scintillators surrounded by a BGO anticoincidence system and a polyethylene neutron shield. The PoGOLite Pathfinder was launched from the SSC Esrange Space Centre in July 2013. A near-circumpolar flight was achieved with a duration of approximately two weeks. The flight performance of the Pathfinder design is discussed for the three Crab observations conducted. The signal-to-background ratio for the observations is shown to be 0.25 ±0.03 and the Minimum Detectable Polarisation (99 % C.L.) is (28.4 ±2.2) %. A strategy for the continuation of the PoGOLite programme is outlined based on experience gained during the 2013 maiden flight.

  2. The design and flight performance of the PoGOLite Pathfinder balloon-borne hard X-ray polarimeter

    CERN Document Server

    Chauvin, M; Jackson, M; Kamae, T; Kawano, T; Kiss, M; Kole, M; Mikhalev, V; Moretti, E; Olofsson, G; Rydström, S; Takahashi, H; Lind, J; Strömberg, J -E; Welin, O; Iyudin, A; Shifrin, D; Pearce, M

    2015-01-01

    In the 50 years since the advent of X-ray astronomy there have been many scientific advances due to the development of new experimental techniques for detecting and characterising X-rays. Observations of X-ray polarisation have, however, not undergone a similar development. This is a shortcoming since a plethora of open questions related to the nature of X-ray sources could be resolved through measurements of the linear polarisation of emitted X-rays. The PoGOLite Pathfinder is a balloon-borne hard X-ray polarimeter operating in the 25 - 240 keV energy band from a stabilised observation platform. Polarisation is determined using coincident energy deposits in a segmented array of plastic scintillators surrounded by a BGO anticoincidence system and a polyethylene neutron shield. The PoGOLite Pathfinder was launched from the SSC Esrange Space Centre in July 2013. A near-circumpolar flight was achieved with a duration of approximately two weeks. The flight performance of the Pathfinder design is discussed for the...

  3. X-ray tests of a Pixel Array Detector for coherent x-ray imaging at the Linac Coherent Light Source

    International Nuclear Information System (INIS)

    Test results are presented of a pixel array detector (PAD) developed for x-ray imaging at the Stanford Linear Coherent Light Source (LCLS). The basic module of the PAD consists of two bump-bonded chips: a reverse-biased silicon diode chip of 185 x 194 pixels, each of which is coupled by bump-bonds to a charge integrating CMOS ASIC with digitization in each pixel. The LCLS experiment requires a high signal-to-noise ratio for detection of single 8 keV x-rays, a pixel full-well exceeding 1,000 8 keV x-rays, a frame-rate of 120 Hz, and the ability to handle the arrival of thousands of x-rays per pixel in tens of femtoseconds. Measurements have verified a pixel full-well value of 2,700 8 keV x-rays. Single 8 keV photon detection has been shown with a signal-to-noise ratio of >6. Line-spread response measurements confirmed charge spreading to be limited to nearest neighbor pixels. Modules still functioned after dosages up to 75 Mrad(Si) at the detector face. Work is proceeding to incorporate an array of modules into a large-area detector.

  4. X-ray multi-energy radiography with scintillator-photodiode detectors

    OpenAIRE

    Naydenov, S. V.; Ryzhikov, V. D.; B.V. Grinyov; Lisetskaya, E. K.; Opolonin, A. D.; Kozin, D. N.

    2002-01-01

    For reconstruction of the spatial structure of many-component objects, it is proposed to use multi-radiography with detection of X-ray by combined detector arrays using detectors of ``scintillator-photodiode'' type. A theoretical model has been developed of multi-energy radiography for thickness measurements of multi-layered systems and systems with defects. Experimental studies of the sensitivity, output signal of various inspection systems based on scintillators $ZnSe(Te)$ and $CsI(Tl)$, an...

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

    Energy Technology Data Exchange (ETDEWEB)

    Quisbert, Elmer Paz Alcon

    2000-03-01

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

  6. Material specific X-ray imaging using an energy-dispersive pixel detector

    International Nuclear Information System (INIS)

    By imaging the X-ray spectral properties or ‘colours’ we have shown how material specific imaging can be performed. Using a pixelated energy-dispersive X-ray detector we record the absorbed and emitted hard X-radiation and measure the energy (colour) and intensity of the photons. Using this technology, we are not only able to obtain attenuation contrast but also to image chemical (elemental) variations inside objects, potentially opening up a very wide range of applications from materials science to medical diagnostics

  7. Material specific X-ray imaging using an energy-dispersive pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Egan, Christopher K., E-mail: christopher.egan@manchester.ac.uk [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Wilson, Matthew D.; Veale, Matthew C.; Seller, Paul [STFC Rutherford Appleton Laboratory, Harwell, Didcot, Oxfordshire OX11 0QX (United Kingdom); Jacques, Simon D.M.; Cernik, Robert J. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom)

    2014-04-01

    By imaging the X-ray spectral properties or ‘colours’ we have shown how material specific imaging can be performed. Using a pixelated energy-dispersive X-ray detector we record the absorbed and emitted hard X-radiation and measure the energy (colour) and intensity of the photons. Using this technology, we are not only able to obtain attenuation contrast but also to image chemical (elemental) variations inside objects, potentially opening up a very wide range of applications from materials science to medical diagnostics.

  8. Digital X-ray microscopy of small biological samples using Medipix2 semiconductor pixel detector

    Czech Academy of Sciences Publication Activity Database

    Dammer, J.; Weyda, František; Jakůbek, J.; Sopko, V.; Žemlička, J.; Hanus, Robert

    Badajoz: Formatex, 2010 - (A. Méndez-Vilas, J.), s. 415-421. (Microscopy Book Series). ISBN 978-84-614-6189-9 R&D Projects: GA MŠk 2B06007; GA AV ČR IAA600550614; GA MŠk 2B06005 Grant ostatní: GA MŠk(CZ) 1P04LA211; GA MŠk(CZ) LC06041 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50070508 Keywords : X-ray imaging * Digital radiography * Computed tomography (CT) * Photon and X-ray detectors Subject RIV: CC - Organic Chemistry

  9. X-ray detectors based on Fe doped GaN photoconductors

    International Nuclear Information System (INIS)

    X-ray detectors based on Fe doped GaN photoconductors have been fabricated. The dark current Id and photocurrent Ip as a function of bias have been investigated and a large Ip/Id ratio of 180 at 200 V has been obtained in spite of optical quenching. The physical mechanism of the transient performance of the photoconductor has been studied through fitting the experimental data. The functions of photocurrent versus acceleration voltage and current of the X-ray source have been measured and discussed. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Annular superconducting tunnel junction detectors: Experimental results under X-ray illumination

    International Nuclear Information System (INIS)

    We present an experiment detecting X-rays by an annular Nb-based Superconducting Tunnel Junction (STJ). In one magnetic field configuration, we stably trapped a single magnetic fluxon in the STJ barrier during the transition to the superconducting state. This is an innovative configuration which avoids the use of an externally applied field during detector operation. This offers potential benefits for STJs used in imaging arrays. In this configuration, and also in the conventional one with an externally applied parallel magnetic field, we observed current pulses produced by single 6 keV X-rays. The pulses were identical for both configurations

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

    OpenAIRE

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

    2008-01-01

    A hybrid pixel detector based on the concept of simultaneous charge integration and photon counting will be presented. The second generation of a counting and integrating X-ray prototype CMOS chip (CIX) has been operated with different direct converting sensor materials (CdZnTe and CdTe) bump bonded to its 8x8 pixel matrix. Photon counting devices give excellent results for low to medium X-ray fluxes but saturate at high rates while charge integration allows the detection of very high fluxes ...

  12. 20-element HgI2 energy dispersive x-ray array detector system

    International Nuclear Information System (INIS)

    This paper describes recent progress in the development of HgI2 energy dispersive x-ray arrays and associated miniaturized processing electronics for synchrotron radiation research applications. The experimental results with a 20-element array detector were obtained under realistic synchrotron beam conditions at SSRL. An energy resolution of 250 eV (FWHM) at 5.9 keV (Mn-Kalpha) was achieved. Energy resolution and throughput measurements versus input count rate and energy of incoming radiation have been measured. Extended X-ray Absorption Fine Structure (EXAFS) spectra were taken form diluted samples simulating proteins with nickel

  13. 20-element HgI[sub 2] energy dispersive x-ray array detector system

    Energy Technology Data Exchange (ETDEWEB)

    Iwanczyk, J.S.; Dorri, N.; Wang, M.; Szczebiot, R.W.; Dabrowski, A.J. (Xsirius, Inc., Marina del Ray, CA (United States)); Hedman, B.; Hodgson, K.O. (Stanford Univ., CA (United States). Stanford Synchrotron Radiation Lab.); Patt, B.E. (EG and G Energy Measurements, Inc., Goleta, CA (United States))

    1992-10-01

    This paper describes recent progress in the development of HgI[sub 2] energy dispersive x-ray arrays and associated miniaturized processing electronics for synchrotron radiation research applications. The experimental results with a 20-element array detector were obtained under realistic synchrotron beam conditions at SSRL. An energy resolution of 250 eV (FWHM) at 5.9 keV (Mn-K[sub alpha]) was achieved. Energy resolution and throughput measurements versus input count rate and energy of incoming radiation have been measured. Extended X-ray Absorption Fine Structure (EXAFS) spectra were taken form diluted samples simulating proteins with nickel.

  14. Visualization tool for X-ray scanner for sTGC detector production quality control

    Science.gov (United States)

    Tikhomirov, V. O.; Filippov, K. A.; Konovalov, S. P.; Mikenberg, G.; Romaniouk, A.; Shchukin, D.; Shoa, M.; Smakhtin, V.; Smirnov, S. Yu; Sosnovtsev, V. V.; Teterin, P. E.; Tsekhosh, V. I.; Vorobev, K. A.

    2016-02-01

    The ATLAS experiment at the Large Hadron Collider has an ambitious program of the detector upgrade to meet an expected rise of accelerator luminosity. The first large system which supposed to be installed in 2019 is the New Small Wheel (NSW) for ATLAS muon spectrometer. In order to ensure high quality and reliability of NSW chambers an X-ray scanning technique is being developed. One of the main components of the X-ray scanner is a special software visualization tool which would allow a fast and clear representation of scanning results and an identification of possible chamber defects.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  17. A novel x-ray detector design with higher DQE and reduced aliasing: Theoretical analysis of x-ray reabsoprtion in detector converter material

    Science.gov (United States)

    Nano, Tomi; Escartin, Terenz; Karim, Karim S.; Cunningham, Ian A.

    2016-03-01

    The ability to improve visualization of structural information in digital radiography without increasing radiation exposures requires improved image quality across all spatial frequencies, especially at high frequencies. The detective quantum efficiency (DQE) as a function of spatial frequency quantifies image quality given by an x-ray detector. We present a method of increasing DQE at high spatial frequencies by improving the modulation transfer function (MTF) and reducing noise aliasing. The Apodized Aperature Pixel (AAP) design uses a detector with micro-elements to synthesize desired pixels and provide higher DQE than conventional detector designs. A cascaded system analysis (CSA) that incorporates x-ray interactions is used for comparison of the theoretical MTF, noise power spectrum (NPS), and DQE. Signal and noise transfer through the converter material is shown to consist of correlated an uncorrelated terms. The AAP design was shown to improve the DQE of both material types that have predominantly correlated transfer (such as CsI) and predominantly uncorrelated transfer (such as Se). Improvement in the MTF by 50% and the DQE by 100% at the sampling cut-off frequency is obtained when uncorrelated transfer is prevalent through the converter material. Optimizing high-frequency DQE results in improved image contrast and visualization of small structures and fine-detail.

  18. Comparison of lens- and fiber-coupled CCD detectors for X-ray computed tomography

    International Nuclear Information System (INIS)

    Lens- and fiber-coupled X-ray detectors with identical CCD chips were compared in their performance in high-resolution computed tomography experiments. X-ray imaging detectors with an identical phosphor and a CCD chip but employing lens- and fiber-coupling between them have been compared. These are designed for X-ray imaging experiments, especially computed tomography, at the medium-length beamline at the SPring-8 synchrotron radiation facility. It was found that the transmittance of light to the CCD is about four times higher in the fiber-coupled detector. The uniformity of response in the lens-coupled detector has a global shading of up to 40%, while pixel-to-pixel variation owing to a chicken-wire pattern was dominant in the fiber-coupled detector. Apart from the higher transmittance, the fiber-coupled detector has a few characteristics that require attention when it is used for computed tomography, which are browning of the fiber, discontinuity in the image, image distortion, and dark spots in the chicken-wire pattern. Thus, it is most suitable for high-speed tomography of samples that tend to deform, for example biological and soft materials

  19. X-ray imaging using a hybrid photon counting GaAs pixel detector

    International Nuclear Information System (INIS)

    The performance of hybrid GaAs pixel detectors as X-ray imaging sensors were investigated at room temperature. These hybrids consist of 300 μm thick GaAs pixel detectors, flip-chip bonded to a CMOS Single Photon Counting Chip (PCC). This chip consists of a matrix of 64 x 64 identical square pixels (170 μm x 170 μm) and covers a total area of 1.2 cm2. The electronics in each cell comprises a preamplifier, a discriminator with a 3-bit threshold adjust and a 15-bit counter. The detector is realized by an array of Schottky diodes processed on semi-insulating LEC-GaAs bulk material. An IV-characteristic and a detector bias voltage scan showed that the detector can be operated with voltages around 200 V. Images of various objects were taken by using a standard X-ray tube for dental diagnostics. The signal to noise ratio (SNR) was also determined. The applications of these imaging systems range from medical applications like digital mammography or dental X-ray diagnostics to non destructive material testing (NDT). Because of the separation of detector and readout chip, different materials can be investigated and compared

  20. Large area, low capacitance Si(Li) detectors for high rate x-ray applications

    International Nuclear Information System (INIS)

    Large area, single-element Si(Li) detectors have been fabricated using a novel geometry which yields detectors with reduced capacitance and hence reduced noise at short amplifier pulse-processing times. A typical device employing the new geometry with a thickness of 6 mm and an active area of 175 mm 2 has a capacitance of only 0.5 pf, compared to 2.9 pf for a conventional planar device with equivalent dimensions. These new low capacitance detectors, used in conjunction with low capacitance field effect transistors, will result in x-ray spectrometers capable of operating at very high count rates while still maintaining excellent energy resolution. The spectral response of the low capacitance detectors to a wide range of x-ray energies at 80 K is comparable to typical state-of-the-art conventional Si(Li) devices. In addition to their low capacitance, the new devices offer other advantages over conventional detectors. Detector fabrication procedures, I-V and C-V characteristics, noise performance, and spectral response to 2-60 keV x-rays are described

  1. CCD [charge-coupled device] sensors in synchrotron x-ray detectors

    International Nuclear Information System (INIS)

    The intense photon flux from advanced synchrotron light sources, such as the 7-GeV synchrotron being designed at Argonne, require integrating-type detectors. Charge-coupled devices (CCDs) are well suited as synchrotron x-ray detectors. When irradiated indirectly via a phosphor followed by reducing optics, diffraction patterns of 100 cm2 can be imaged on a 2 cm2 CCD. With a conversion efficiency of ∼1 CCD electron/x-ray photon, a peak saturation capacity of >106 x rays can be obtained. A programmable CCD controller operating at a clock frequency of 20 MHz has been developed. The readout rate is 5 x 106 pixels/s and the shift rate in the parallel registers is 106 lines/s. The test detector was evaluated in two experiments. In protein crystallography diffraction patterns have been obtained from a lysozyme crystal using a conventional rotating anode x-ray generator. Based on these results we expect to obtain at a synchrotron diffraction images at the rate of ∼1 frame/s or a complete 3-dimensional data set from a single crystal in ∼2 min. 16 refs., 16 figs., 2 tabs

  2. Fast photoconductor CdTe detectors for synchrotron x-ray studies

    International Nuclear Information System (INIS)

    The Advanced Photon Source will be that brightest source of synchrotron x-rays when it becomes operational in 1996. During normal operation, the ring will be filled with 20 bunches of positrons with an interbunch spacing of 177 ns and a bunch width of 119 ps. To perform experiments with x-rays generated by positrons on these time scales one needs extremely high speed detectors. To achieve the necessary high speed, we are developing MBE-grown CdTe-base photoconductive position sensitive array detectors. The arrays fabricated have 64 pixels with a gap of 100 μm between pixels. The high speed response of the devices was tested using a short pulse laser. X-ray static measurements were performed using an x-ray tube and synchrotron radiation to study the device's response to flux and wavelength changes. This paper presents the response of the devices to some of these tests and discusses different physics aspects to be considered when designing high speed detectors

  3. A dual detector approach for X-ray differential phase contrast imaging

    International Nuclear Information System (INIS)

    Phase sensitive X-ray imaging methods can provide substantially improved contrast over conventional absorption-based techniques, and therefore new and inaccessible information. Here we propose a dual detector approach for X-ray differential phase contrast imaging, which allows a quantitative retrieval of the object's phase information by a single exposure. The analysis performed in our research shows that compared with the phase-stepping method, the dual detector approach is advantageous in fast imaging speed, reduced radiation dose and alignment errors, and avoiding any problems resulting from motion artifacts and X-ray exposure reproducibility. The approach has a direct extension to single exposure two-dimensional differential phase contrast imaging, as well as the possibility to perform three-dimensional reconstruction of the refractive index and its gradient field. We believe that this approach can find its potential in clinical applications, where imaging speed and radiation dose are critical issues. - Highlights: ► Dual detector approach for single-shot X-ray differential phase contrast imaging. ► Quantitative retrieval of the object's phase information by a single exposure. ► Advantageous in fast imaging speed and reduced radiation dose

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

    International Nuclear Information System (INIS)

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

  5. Segmented Monolithic Germanium Detector Arrays for X-ray Absorption Spectroscopy. Final Report

    International Nuclear Information System (INIS)

    The experimental results from the Phase I effort were extremely encouraging. During Phase I PHDs Co. made the first strides toward a new detector technology that could have great impact on synchrotron x-ray absorption (XAS) measurements, and x-ray detector technology in general. Detector hardware that allowed critical demonstration measurements of our technology was designed and fabricated. This new technology allows good charge collection from many pixels on a single side of a multi-element monolithic germanium planar detector. The detector technology provides 'dot-like' collection electrodes having very low capacitance. The detector technology appears to perform as anticipated in the Phase I proposal. In particular, the 7-pixel detector studied showed remarkable properties; making it an interesting example of detector physics. The technology is enabled by the use of amorphous germanium contact technology on germanium planar detectors. Because of the scalability associated with the fabrication of these technologies at PHDs Co., we anticipate being able to supply larger detector systems at significantly lower cost than systems made in the conventional manner.

  6. Feasibility study of a gas electron multiplier detector as an X-Ray image sensor

    Science.gov (United States)

    Shin, Sukyoung; Jung, Jaehoon; Lee, Soonhyouk

    2015-07-01

    For its ease of manufacture, flexible geometry, and cheap manufacturing cost, the gas electron multiplier (GEM) detector can be used as an X-ray image sensor. For this purpose, we acquired relative detection efficiencies and suggested a method to increase the detection efficiency in order to study the possibility of using a GEM detector as an X-ray image sensor. The GEM detector system is composed of GEM foils, the instrument system, the gas system, and the negative power supply. The instrument system consists of an A225 charge sensitive preamp, an A206 discriminator, and a MCA8000D multichannel analyzer. For the gas system, argon gas was mixed with CO2 in a ratio of 8:2, and for the negative 2,000 volts, a 3106D power supply was used. A CsI-coated GEM foil was used to increase the detection efficiency. Fe-55 was used as an X-ray source, and the relative efficiency was acquired by using the ratio of the efficiency of the GEM detector to that of the CdTe detector. The total count method and the energy spectrum method were used to calculate the relative efficiency. The relative detection efficiency of the GEM detector for Fe-55 by using total count method was 32%, and the relative detection efficiencies were 5, 43, 33, 37, 35, and 36%, respectively, for 2-, 3-, 4-, 5-, 6-, and 7- keV energy spectrum by using the energy spectrum method. In conclusion, we found that the detection efficiency of the two-layered GEM detector is insufficient for use as an X-ray image sensor, so we suggest a CsI-coated GEM foil to increase the efficiency, with resulting value being increased to 41%.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2016-03-01

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

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

    CERN Document Server

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

    2002-01-01

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

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

    International Nuclear Information System (INIS)

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

  11. Study of commercial Si-PIN photodiode as an x-ray detector

    International Nuclear Information System (INIS)

    Two commercial Si-PIN photodiode were evaluated as a low cost X-ray detector in conjunction with forward biased FET preamplifiers. Evaluation was done at room temperature and at a temperature of about -10degC using X-ray spectroscopy amplifier with 241Am radio active source. The results shows 700 eV full width at half maximum for 241Am γ-ray (59.5 keV) with S5821-02 from Hamamatsu Photonics at low temperature and 800 eV with S1722-02 at the same conditions. The S1722-02 photodiode showed almost flat response up to 20 keV X-ray energy. The improvement of photodiode and FET cooling system and proper selection of FET will be expected to show better resolution. (author)

  12. Breast cancer calcification measurements using direct X-ray detection in a monolithic silicon pixel detector

    International Nuclear Information System (INIS)

    A prototype monolithic silicon pixel detector, developed for high-precision tracking at the Superconducting Super Collider, has been used to measure, by direct detection of x-rays, aluminum oxide grains from an accreditation phantom, and calcifications from a tissue sample including a calcification with a width of 100 μm (about half the diameter of the smallest ones normally seen in clinical practice). A computer model indicates that a future sensor, using the same basic structure but optimized for mammography, has the potential of improving upon the abilities of scintillator-film and scintillator-CCD systems by observing individual x-rays, thus allowing the possibility of combining high resolution digital information from more than one viewing angle or x-ray energy

  13. Performance of silicon-drift detectors in kaonic atom X-ray measurements

    Energy Technology Data Exchange (ETDEWEB)

    Bazzi, M. [INFN, Laboratori Nazionali di Frascati, Frascati (Roma) (Italy); Beer, G. [Department of Physics and Astronomy, University of Victoria, Victoria, BC (Canada); Bombelli, L. [Politechno di Milano, Sez. di Elettronica, Milano (Italy); Bragadireanu, A.M. [INFN, Laboratori Nazionali di Frascati, Frascati (Roma) (Italy); IFIN-HH, Magurele, Bucharest (Romania); Cargnelli, M. [Stefan-Meyer-Institut fuer subatomare Physik, Boltzmanngasse 3, Vienna (Austria); Corradi, G.; Curceanu, C.; D' Uffizi, A. [INFN, Laboratori Nazionali di Frascati, Frascati (Roma) (Italy); Fiorini, C.; Frizzi, T. [Politechno di Milano, Sez. di Elettronica, Milano (Italy); Ghio, F.; Girolami, B. [INFN Sez. di Roma I and Inst. Superiore di Sanita, Roma (Italy); Guaraldo, C. [INFN, Laboratori Nazionali di Frascati, Frascati (Roma) (Italy); Hayano, R.S. [University of Tokyo, Tokyo (Japan); Iliescu, M. [INFN, Laboratori Nazionali di Frascati, Frascati (Roma) (Italy); IFIN-HH, Magurele, Bucharest (Romania); Ishiwatari, T., E-mail: tomoichi.ishiwatari@assoc.oeaw.ac.a [Stefan-Meyer-Institut fuer subatomare Physik, Boltzmanngasse 3, Vienna (Austria); Iwasaki, M. [RIKEN, The Institute of Physical and Chemical Research, Saitama (Japan); Kienle, P. [Stefan-Meyer-Institut fuer subatomare Physik, Boltzmanngasse 3, Vienna (Austria); Tech. Univ. Muenchen, Physik Dep., Garching (Germany); Levi Sandri, P. [INFN, Laboratori Nazionali di Frascati, Frascati (Roma) (Italy); Longoni, A. [Politechno di Milano, Sez. di Elettronica, Milano (Italy)

    2011-02-01

    Large-area silicon drift detectors (SDDs) were used for the first time in the background condition of a collider for precision spectroscopy of the kaonic atom X-rays in the SIDDHARTA experiment for the study of the strong interaction in a low-energy regime. The measurements were performed at the DA{Phi}NE electron-positron collider (LNF, Italy), using gas targets of hydrogen, deuterium, helium-3, and helium-4. A test measurement using the kaonic {sup 4}He X-rays showed an excellent performance of the SDD devices under the beam conditions, and a good background suppression capability using the time correlation between the kaonic atom X-rays and the back-to-back correlated K{sup +}K{sup -} pairs produced by {phi} decays.

  14. Performance of silicon-drift detectors in kaonic atom X-ray measurements

    International Nuclear Information System (INIS)

    Large-area silicon drift detectors (SDDs) were used for the first time in the background condition of a collider for precision spectroscopy of the kaonic atom X-rays in the SIDDHARTA experiment for the study of the strong interaction in a low-energy regime. The measurements were performed at the DAΦNE electron-positron collider (LNF, Italy), using gas targets of hydrogen, deuterium, helium-3, and helium-4. A test measurement using the kaonic 4He X-rays showed an excellent performance of the SDD devices under the beam conditions, and a good background suppression capability using the time correlation between the kaonic atom X-rays and the back-to-back correlated K+K- pairs produced by φ decays.

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

    CERN Document Server

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

    2006-01-01

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

  16. Effects of Fiber-optic Plates on Image Quality of CMOS X-ray Detectors

    International Nuclear Information System (INIS)

    Radiation damage and its effects on image quality of Complementary metal-oxide-semiconductor (CMOS) devices have also been reported by previous studies. In this regard, most CMOS sensor manufacturers usually employ a fiber-optic plate (FOP) bonded to the CMOS photodiode array. In this configuration, the FOP layer absorbs un-attenuated x-ray photons through an overlaid scintillator; otherwise the un-attenuated photons might be absorbed within the CMOS photodiode array directly. Therefore, it is important to select an optimal thickness of an FOP layer for the long-term use of CMOS sensors providing high-quality images. By comparing the image qualities of the CMOS detector measured without and with FOP, the effects of FOP on the imaging system have been investigated for various x-ray spectra. Measurements showed that the FOP degraded the x-ray sensitivity and resolving power, whereas it enhanced noise properties by absorbing un-attenuated x-ray photons. As a result, the use of FOP enhances the DQE performance which mainly governs x-ray image quality. However, for a low exposure imaging, the use of FOP may not be appropriate because it reduces the light photon transmittance by ∼55% which implies that the image quality could be easily affected by additional electronics noise rather than quantum noise. In this regard, the use of FOP may be more appropriate for industrial applications in which irradiation condition is harsh

  17. Effects of Fiber-optic Plates on Image Quality of CMOS X-ray Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Seungman; Han, Jong Chul; Kim, Ho Kyung [Pusan National Univ., Busan (Korea, Republic of)

    2014-05-15

    Radiation damage and its effects on image quality of Complementary metal-oxide-semiconductor (CMOS) devices have also been reported by previous studies. In this regard, most CMOS sensor manufacturers usually employ a fiber-optic plate (FOP) bonded to the CMOS photodiode array. In this configuration, the FOP layer absorbs un-attenuated x-ray photons through an overlaid scintillator; otherwise the un-attenuated photons might be absorbed within the CMOS photodiode array directly. Therefore, it is important to select an optimal thickness of an FOP layer for the long-term use of CMOS sensors providing high-quality images. By comparing the image qualities of the CMOS detector measured without and with FOP, the effects of FOP on the imaging system have been investigated for various x-ray spectra. Measurements showed that the FOP degraded the x-ray sensitivity and resolving power, whereas it enhanced noise properties by absorbing un-attenuated x-ray photons. As a result, the use of FOP enhances the DQE performance which mainly governs x-ray image quality. However, for a low exposure imaging, the use of FOP may not be appropriate because it reduces the light photon transmittance by ∼55% which implies that the image quality could be easily affected by additional electronics noise rather than quantum noise. In this regard, the use of FOP may be more appropriate for industrial applications in which irradiation condition is harsh.

  18. The use of cadmium telluride detectors for the qualitative analysis of diagnostic x-ray spectra.

    Science.gov (United States)

    Di Castro, E; Pani, R; Pellegrini, R; Bacci, C

    1984-09-01

    A method is introduced for the evaluation of x-ray spectra from x-ray machines operating in the range 50-100 kVp using a cadmium telluride (CdTe) detector with low detection efficiency. The pulse height distribution obtained with this kind of detector does not represent the true photon spectra owing to the presence of K-escape, Compton scattering, etc.; these effects were evaluated using a Monte Carlo method. A stripping procedure is described for implementation on a Univac 1100/82 computer. The validity of our method was finally tested by comparison with experimental results obtained with a Ge detector and with data from the literature; the results are in good agreement with published data. PMID:6483976

  19. Recent Progress on Developments and Characterization of Hybrid CMOS X-ray Detectors

    CERN Document Server

    Falcone, Abe D; Griffith, Christopher; Bongiorno, Stephen; Burrows, David N

    2012-01-01

    Future space-based X-ray telescope missions are likely to have significantly increased demands on detector read out rates due to increased collection area, and there will be a desire to minimize radiation damage in the interests of maintaining spectral resolution. While CCDs have met the requirements of past missions, active pixel sensors are likely to be a standard choice for some future missions due to their inherent radiation hardness and fast, flexible read-out architecture. One form of active pixel sensor is the hybrid CMOS sensor. In a joint program of Penn State University and Teledyne Imaging Sensors, hybrid CMOS sensors have been developed for use as X-ray detectors. Results of this development effort and tests of fabricated detectors will be presented, along with potential applications for future missions.

  20. Current applications of semiconductor x-ray detectors in chemical analysis

    International Nuclear Information System (INIS)

    In the last few years, semiconductor detectors have been used as X-ray detectors with great success, and the routine rapid accumulation of X-ray spectra is now possible. This review surveys the historical development of the detectors, the utilisation, and relative merits of various means of exciting the X-radiation from the elements in the sample, and compares the technique with other methods claiming to offer the capability of simultaneous multi-element analysis. It is concluded that it is of average sensitivity, but offers some advantages from its non-destructive nature, and in some cases its ability to offer information about the spatial distribution of elements in a sample. Other types of analysis may also be possible simultaneously. Sample preparation techniques are reviewed, especially techniques of manufacturing thin samples. An appendix contains details of the very wide variety of samples which have been analysed. More than 350 references are included. (auth.)

  1. A multi-channel monolithic Ge detector system for fluorescence x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Construction and performance of a monolithic quad-pixel Ge detector for fluorescence x-ray absorption spectroscopy (XAS) at synchrotron radiation sources are described. The detector semiconductor element has an active surface area of 4.0 cm2 which is electrically separated into four 1.0 cm2 pixels, with little interfacial dead volume. Spatial response of the array shows that cross-talk between adjacent pixels is 55Fe test source (MnKα, 5.9 keV), energy resolution of better than 200 eV is achieved with a 4 μsec peaking time. At 0.5 μsec peaking time, pulse pileup results in a 75% throughput efficiency for an incoming count rate of 100 kHz. Initial XAS fluoresncece measurements at the beamline 4 wiggler end stations at SSRL show that the detector system has several advantages over commercial x-ray spectrometers for low-concentration counting

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  4. Discriminating cosmic muon and x-ray based on rising time using GEM detector

    CERN Document Server

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

    2015-01-01

    Gas electron multiplier(GEM) detector is used in Cosmic Muon Scattering Tomography and neutron imaging in the last decade. In this work, a triple GEM device with an effective readout area of 10 cm X 10 cm is developed, and an experiment of discriminating between cosmic muon and x-ray based on rising time is tested. The energy resolution of GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. The analysis of the complete signal-cycles allows to get the rising time and pulse heights. The experiment result indicates that cosmic muon and x-ray can be discriminated with an appropriate rising time threshold.

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

    CERN Document Server

    Shin, Sukyoung; Lee, Soonhyouk

    2015-01-01

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

  6. Low-dose performance of wafer-scale CMOS-based X-ray detectors

    Science.gov (United States)

    Maes, Willem H.; Peters, Inge M.; Smit, Chiel; Kessener, Yves; Bosiers, Jan

    2015-03-01

    Compared to published amorphous-silicon (TFT) based X-ray detectors, crystalline silicon CMOS-based active-pixel detectors exploit the benefits of low noise, high speed, on-chip integration and featuring offered by CMOS technology. This presentation focuses on the specific advantage of high image quality at very low dose levels. The measurement of very low dose performance parameters like Detective Quantum Efficiency (DQE) and Noise Equivalent Dose (NED) is a challenge by itself. Second-order effects like defect pixel behavior, temporal and quantization noise effects, dose measurement accuracy and limitation of the x-ray source settings will influence the measurements at very low dose conditions. Using an analytical model to predict the low dose behavior of a detector from parameters extracted from shot-noise limited dose levels is presented. These models can also provide input for a simulation environment for optimizing the performance of future detectors. In this paper, models for predicting NED and the DQE at very low dose are compared to measurements on different CMOS detectors. Their validity for different sensor and optical stack combinations as well as for different x-ray beam conditions was validated.

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

    Science.gov (United States)

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

    2015-12-01

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

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

    International Nuclear Information System (INIS)

    An X-ray imaging detector has been developed for dental applications. The principle of this detector is based on application of a silicon charge coupled device covered by a scintillating wave-guide screen. Previous studies of such a detector showed promising results concerning the spatial resolution but low performance in terms of signal to noise ratio (SNR) and sensitivity. Recent results confirm the wave-guiding properties of the matrix and show improvement of the detector in terms of response uniformity, sensitivity and SNR. The present study is focussed on the fabrication of the scintillating screen where the principal idea is to fill a matrix of Si pores with a CsI scintillator. The photoluminescence technique was used to prove the wave-guiding property of the matrix and to inspect the filling uniformity of the pores. The final detector was characterized by X-ray evaluation in terms of spatial resolution, light output and SNR. A sensor with a spatial resolution of 9 LP/mm and a SNR over 50 has been achieved using a standard dental X-ray source and doses in the order of those used at the moment by dentists (around 25 mR)

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

    CERN Document Server

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

    1999-01-01

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

  10. Cascaded-systems analyses of photon-counting x-ray detectors

    Science.gov (United States)

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

    2013-03-01

    Single-photon counting (SPC) x-ray imaging has the potential to improve image quality and enable new advanced energy-dependent methods. Recently, cascaded systems analysis (CSA) has been extended to the description of the detective quantum efficiency (DQE) of SPC detectors. In this article we apply the new CSA approach to the description of the DQE of hypothetical direct-conversion selenium (Sc) and cadmium zinc telluride (CdZnTc) detectors including the effects of poly-energetic x-ray spectra, stochastic conversion of x-ray energy to electron­ hole (c-h) pairs, depth-dependent collection of e-h pairs using the Hecht relation, additive electronic noise, and thresholding. Comparisons arc made to an energy-integrating model. For this simple model, with the exception of thick (1- 10 mm) Sc-bascd convertors, we found that the SPC DQE was 5-20 %greater than that of the energy­ integrating model. This trend was tnw even when additive noise was included in the SPC model and excluded from the energy-integrating model. However, the DQE of SPC detectors with poor collection efficiency (such as thick (approaches arc not yet ready for routine diagnostic imaging, the available DQE is equal to or higher than that of conventional energy-integrating detectors under a wide range of x-ray energies and convertor thickness. However, like energy-integrating detectors, the DQE of SPC detectors will be degraded by the combination of poor collection efficiency and high levels of additive noise.

  11. Balloon-borne hard X-ray polarimetry with PoGOLite

    CERN Document Server

    ,

    2012-01-01

    PoGOLite is a hard X-ray polarimeter operating in the 25-100 keV energy band. The instrument design is optimised for the observation of compact astrophysical sources. Observations are conducted from a stabilised stratospheric balloon platform at an altitude of approximately 40 km. The primary targets for first balloon flights of a reduced effective area instrument are the Crab and Cygnus-X1. The polarisation of incoming photons is determined using coincident Compton scattering and photo-absorption events reconstructed in an array of plastic scintillator detector cells surrounded by a bismuth germanate oxide (BGO) side anticoincidence shield and a polyethylene neutron shield. A custom attitude control system keeps the polarimeter field-of-view aligned to targets of interest, compensating for sidereal motion and perturbations such as torsional forces in the balloon rigging. An overview of the PoGOLite project is presented and the outcome of the ill-fated maiden balloon flight is discussed.

  12. Development of an ultra-low-power x-ray-photon-resolving imaging detector array

    Science.gov (United States)

    Sun, Shunming; Downey, Stephen; Gaalema, Stephen; Gates, James L.; Jernigan, J. Garrett; Kaaret, Philip; MacIntosh, Scott; Ramsey, Brian; Wall, Bruce

    2010-08-01

    We report on progress to develop and demonstrate CZT and Si hybrid detector arrays for future NASA missions in X-ray and Gamma-ray astronomy. The primary goal for these detectors is consistent with the design concept for the EXIST mission1 and will also be appropriate for other NASA applications and ground-based projects. In particular we target science instruments that have large aperture (multiple square meters) and therefore require a low power ROIC (readout integrated circuits) design (energy resolution for single photon detection for X rays in the range 5-600 keV with a CZT sense layer and 2-30 keV with a Si sense layer. The target CZT arrays are 2 cm × 2 cm with 600 micron square-shaped pixels. The low power smart pixel detects rare X-ray hits with an adjustable threshold setting. A test array of 7 × 5 pixels with a 5 mm thick CZT sense layer demonstrates that the low power pixel can successfully detect X-rays with {50 readout noise electrons RMS.

  13. The speedster-EXD: a new event-triggered hybrid CMOS x-ray detector

    Science.gov (United States)

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

    2014-07-01

    We present preliminary characterization of the Speedster-EXD, a new event driven hybrid CMOS detector (HCD) developed in collaboration with Penn State University and Teledyne Imaging Systems. HCDs have advantages over CCDs including lower susceptibility to radiation damage, lower power consumption, and faster read-out time to avoid pile-up. They are deeply depleted and able to detect x-rays down to approximately 0.1 keV. The Speedster-EXD has additional in-pixel features compared to previously published HCDs including: (1) an in-pixel comparator that enables read out of only the pixels with signal from an x-ray event, (2) four different gain modes to optimize either full well capacity or energy resolution, (3) in-pixel CDS subtraction to reduce read noise, and (4) a low-noise, high-gain CTIA amplifier to eliminate interpixel capacitance crosstalk. When using the comparator feature, the user can set a comparator threshold and only pixels above the threshold will be read out. This feature can be run in two modes including single pixel readout in which only pixels above the threshold are read out and 3x3 readout where a 3×3 region centered on the central pixel of the X-ray event is read out. The comparator feature of the Speedster-EXD increases the detector array effective frame rate by orders of magnitude. The new features of the Speedster-EXD hybrid CMOS x-ray detector are particularly relevant to future high throughput x-ray missions requiring large-format silicon imagers.

  14. X-ray Performance Evaluation of the Dexela CMOS APS X-ray Detector Using Monochromatic Synchrotron Radiation in the Mammographic Energy Range

    OpenAIRE

    Konstantinidis, A. C.; Szafraniec, M. B.; Rigon, L.; Tromba, G.; Dreossi, D.; Sodini, N.; Liaparinos, P. F.; Naday, S.; Gunn, S.; McArthur, A.; Speller, R.D.; Olivo, A.

    2013-01-01

    Digital detectors based on complementary metaloxide-semiconductors (CMOS) active pixel sensor (APS) technology have been introduced recently in many scientific applications. This work is focused on the X-ray performance evaluation of a novel CMOS APS detector in low energy medical imaging applications using monochromatic synchrotron radiation (i.e., 17–35 keV), which also allows studying how the performance varies with energy. The CMOS sensor was coupled to a Thallium-activated structured ces...

  15. Development and features of an X-ray detector with high spatial resolution

    International Nuclear Information System (INIS)

    A laboratory model of an X-ray detector with high spatial resolution was developed and constructed. It has no spectral resolution, but a local resolution of 20 μm which is about ten times as high as that of position-sensitive proportional counters and satisfies the requirements of the very best Wolter telescopes with regard to spatial resolution. The detector will be used for laboratory tests of the 80 cm Wolter telescope which is being developed for Spacelab flights. The theory of the wire grid detector and the physics of the photoelectric effect has been developed, and model calculations and numerical calculations have been carried out. (orig./WB)

  16. Discriminating cosmic muon and x-ray based on rising time using GEM detector

    OpenAIRE

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

    2015-01-01

    Gas electron multiplier(GEM) detector is used in Cosmic Muon Scattering Tomography and neutron imaging in the last decade. In this work, a triple GEM device with an effective readout area of 10 cm X 10 cm is developed, and an experiment of discriminating between cosmic muon and x-ray based on rising time is tested. The energy resolution of GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. The analysis of the complete signal-cycles allows to get the ri...

  17. CdTe X-ray detectors for medical computerized tomography

    International Nuclear Information System (INIS)

    The kinetic and lux-ampere characteristics (BAC) of pure CdTe crystals of p- and n-types used as X-ray detectors for medical tomography are studied. It is shown that proper reproducibility of the excitation pulse form, strict LAC linearity and low photocurrent memary of the detectors with a regquired maintained sensitivity maintained may be attained using semi-insulating cadmium telluride crystals with a low concentration of adhesion centers equal to the concentration of recombination levels. In that case, the detector should operate under the double injection regime

  18. A versatile indirect detector design for hard X-ray microimaging

    International Nuclear Information System (INIS)

    Indirect X-ray detectors are of outstanding importance for high resolution imaging, especially at synchrotron light sources: while consisting mostly of components which are widely commercially available, they allow for a broad range of applications in terms of the X-ray energy employed, radiation dose to the detector, data acquisition rate and spatial resolving power. Frequently, an indirect detector consists of a thin-film single crystal scintillator and a high-resolution visible light microscope as well as a camera. In this article, a novel modular-based indirect design is introduced, which offers several advantages: it can be adapted for different cameras, i.e. different sensor sizes, and can be trimmed to work either with (quasi-)monochromatic illumination and the correspondingly lower absorbed dose or with intense white beam irradiation. In addition, it allows for a motorized quick exchange between different magnifications / spatial resolutions. Developed within the European project SCINTAX, it is now commercially available. The characteristics of the detector in its different configurations (i.e. for low dose or for high dose irradiation) as measured within the SCINTAX project will be outlined. Together with selected applications from materials research, non-destructive evaluation and life sciences they underline the potential of this design to make high resolution X-ray imaging widely available.

  19. MIS tunnel diode as a low energy X-ray and gamma-ray detector

    International Nuclear Information System (INIS)

    Highly perfect n-type cadmium telluride single crystals have been used to fabricate semiconductor detectors for X-ray and low energy gamma-ray spectrometry at room temperature. The detectors are of MIS tunnel diode type. Between the metal (M) and the semiconducting CdTe crystals (S) there is a thin insulator (D) with a critical value of thickness. The mechanism for a current condition is tunneling through the insulator. Our studies by SIMS and ellipsometry show that there is a nonstoichiometric region between the insulator and the semiconductor and in the insulator with thickness below 30 A. The effect of the nonstoichiometry in the MIS structure upon spectrometric performance of the detector has been analyzed. A considerable improvement of the energy resolution for full energy peak can be achieved by appropriate interfaces of the MIS tunnel detectors. The Np - Lα (13.9 keV), Np -Lβ (17.7 keV) and Np -Lγ (20.8 keV) X-ray are clearly resolved. The spectrum of the characteristic X-ray from 55Fe source (5.9 keV) shows the energy resolution to 0.9 keV (FWHM) at room temperature. (author)

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

    Science.gov (United States)

    Jiang, Hao; Kaercher, Joerg; Durst, Roger

    2016-03-01

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

  1. Performance of room temperature mercuric iodide (HgI2) detectors in the ultra low energy x-ray region

    International Nuclear Information System (INIS)

    Performance of room temperature mercuric iodide x-ray spectrometers has been recently improved through new fabrication techniques and further development of low noise associated electronic systems. This progress has extended the range of measurements to the ultra low energy x-ray region at room temperature. This paper reports the study of the effect of contact material on the performance of HgI2 detectors in the low energy x-ray region

  2. Entrance windows in germanium low-energy x-ray detectors

    International Nuclear Information System (INIS)

    It was found experimentally that high-purity Ge low-energy X-ray detectors have a relatively thick entrance window which renders them practically useless below approximately 2.3 keV. A simple X-ray fluorescence experiment establishes clearly that the window is physically in the Ge material itself. Experiments with detectors made from different Ge crystals, and with Schottky barrier contacts of different metals indicate that the effect is due to a basic property of the transport of electrons near a surface. Theoretical considerations and a Monte Carlo calculation show that the window is caused by the escape of warm electrons which are the end product of a photo event. The mean free path of the electrons becomes longer as they lose energy by optical phonon collisions and they can be trapped at the surface before they are picked up by the electric field

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

    CERN Document Server

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

    2002-01-01

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

  4. A superconducting tunnel junction X-ray detector design for practical applications

    International Nuclear Information System (INIS)

    Superconducting tunnel junctions coupled to a superconducting absorber can be used as a high-resolution energy-dispersive X-ray detector. The energy of an absorbed X-ray breaks Cooper pairs in the absorber, producing quasiparticles. These quasiparticles can tunnel through the barrier and be counted. When used in conjunction with FET electronics, however, the noise requirements limit the area of the tunnel junction. In many designs, this also limits the absorber area. We present a detector design that separates the absorber from the junction. It features a tantalum absorber for high absorption efficiency and an aluminum transport layer for rapid, low loss transport to the junction. Transport is aided by multiple trapping stages, while fabrication is simplified by using only two materials. (orig.)

  5. Note: Continuing improvements on the novel flat-response x-ray detector

    International Nuclear Information System (INIS)

    This note describes multi-updates of the novel flat-response x-ray detector in fabrication technology, experimental application, and data uncertainty evaluation. Unlike the previous design, the compound filter is combined into one piece through an improved fabrication process that greatly enhanced its self-supporting capability. A method of pinhole-array imaging is introduced into the experimental application process to stop any debris from the hohlraum and to uniformly reduce the radiation flux. The experimental results show that this method works well. Furthermore, a method of uncertainty evaluation of the radiation flux measurement by the novel flat-response x-ray detector has been developed. The influence of the radiation spectrum to the flux measurement is analyzed. The evaluation shows that the relative uncertainty of the radiation flux is about 10% in higher radiation temperature condition (Tr > 150 eV) and 16% in lower radiation temperature condition (Tr < 100 eV).

  6. A liquid-helium cooled large-area silicon PIN photodiode X-ray detector

    International Nuclear Information System (INIS)

    An X-ray detector using a liquid-helium cooled large-area silicon PIN photodiode has been developed along with a tailor-made charge sensitive preamplifier whose first-stage JFET has been cooled. The operating temperature of the JFET has been varied separately and optimized. The X- and γ-ray energy spectra for an 241Am source have been measured with the photodiode operated at 13 K. An energy resolution of 1.60 keV (FWHM) has been obtained for 60-keV γ rays and 1.30 keV (FWHM) for the pulser. The energy threshold could be set as low as 3 keV. It has been shown that a silicon PIN photodiode serves as a low-cost excellent X-ray detector which covers a large area at 13 K. (orig.)

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

    International Nuclear Information System (INIS)

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

  8. Characterization of Si hybrid CMOS detectors for use in the soft x-ray band

    Science.gov (United States)

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

    2013-09-01

    We report on the characterization of four HAWAII Hybrid Si CMOS detectors (HCD) developed for use as X-ray detectors as part of a joint program between Penn State University and Teledyne Imaging Sensors (TIS). Interpixel capacitive crosstalk (IPC) has been measured for standard H1RG detectors as well as a specially developed H2RG that uses a unique bonding structure. The H2RG shows significant reduction in IPC, as reported by Griffith et al. 2012. Energy resolution at 1.5 & 5.9 keV was measured as well as read noise for each detector. Dark current as a function of temperature is reported from 150 - 210 K and dark current figures of merit are estimated for each detector. We also discuss upcoming projects including testing of a new HCD called the Speedster-EXD. This prototype detector will have a low noise, high gain CTIA to reduce IPC and read noise as well as in-pixel CDS and event flagging. In the coming year PSU and TIS will begin work on a project to incorporate CTIA and CDS circuitry into the ROIC of a HAWAII HCD like detector to satisfy the small pixel and high rate needs of future X-ray observatories.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-08-15

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

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

    International Nuclear Information System (INIS)

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

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

    Czech Academy of Sciences Publication Activity Database

    Jandejsek, Ivan; Jakůbek, J.; Jakůbek, M.; Průcha, P.; Krejčí, F.; Soukup, P.; Tureček, D.; Vavřík, Daniel; Žemlička, J.

    2014-01-01

    Roč. 9, May (2014), C05062. ISSN 1748-0221. [International workshop on radiation imaging detectors /15./. Paris, 23.06.2013-27.06.2013] Institutional support: RVO:68378297 Keywords : inspection with x-rays * detection of defects Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.399, year: 2014 http://iopscience.iop.org/1748-0221/9/05/C05062

  12. Portable X-ray fluorescence spectrometer using XR-100CR detector

    International Nuclear Information System (INIS)

    Si-PIN photodiode has been being used as radiation detection probe since not long ago. But with obvious advantages as high energy resolution, needless liquid nitrogen and stable operation, this type of probe has been using more and more. The XR100-CR detector including a thermoelectricity cooled Si-PIN photodiode as an X-ray detector, a charge sensitive preamplifier and a novel -30oC temperature regulation electronic circuit is enclosed in a single miniature package. It has small enclosure size (9.5 x 4.4 x 2.9 cm), light weight (125 g), high energy resolution (the 5.9 keV peak of 55Fe is 186 eV FWHM with 20 μs shaping time) and low power consumption (< 1 Watt). With these facilities, this detector is able to use for in-site and outdoor X-ray Fluorescence analysis applications. Nowadays, compact X-ray spectrometers using XR100-CR are installed in factories produce cement, steel, paper, glass and ceramic, etc. to monitor interested chemical elements. Portable X-ray spectrometers are also promoted for outdoor non-destructive analysis of various objects, that we want to know some chemical elements in their composition, such as steel pipes, minerals, antiques and containers, etc. Moreover, electronic devices are more better and specialization with every passing day. The preeminence of XR100-CR detector and modern electronics have been bringing XRF analysis techniques to existence human activities. The portable XRF equipment described in this report is a multifunctional instrument for in-situ, non-destructive and real-time analysis of alloys, minerals, chemicals, papers, and glasses, etc. It was designed by Nuclear Electronics Department (NED) and the XRF group of Radiation Safety and Environment Department, Center for Nuclear Techniques, HCMC. (author)

  13. An updated system of electronic modules for X-ray spectrometers with cooled semiconductor detectors

    International Nuclear Information System (INIS)

    An updated system of program-controlled analog and analog-to-digital modules for X-ray spectrometers with semiconductor detectors is reported. Ways to increase the count rate capacity of pulse-drain feedback charge-sensitive preamplifiers to 106 cps for EX=5.9 keV are considered in detail. A new analog processor model AP-007 incorporating Kandiah's cusp-shaper is described. Some problems of further improvements in the modular system are discussed. (orig.)

  14. Recent Progress on Developments and Characterization of Hybrid CMOS X-ray Detectors

    OpenAIRE

    Falcone, Abe D.; Prieskorn, Zachary; Griffith, Christopher; Bongiorno, Stephen; Burrows, David N.

    2012-01-01

    Future space-based X-ray telescope missions are likely to have significantly increased demands on detector read out rates due to increased collection area, and there will be a desire to minimize radiation damage in the interests of maintaining spectral resolution. While CCDs have met the requirements of past missions, active pixel sensors are likely to be a standard choice for some future missions due to their inherent radiation hardness and fast, flexible read-out architecture. One form of a...

  15. Design of soft-X-ray tomographic system in WEST using GEM detectors

    Czech Academy of Sciences Publication Activity Database

    Mazon, D.; Chernyshova, M.; Jiolat, G.; Czarski, T.; Malard, P.; Kowalska-Strzeciwilk, E.; Jablonski, S.; Figacz, W.; Zagorski, R.; Kubkowska, M.; Kasprowicz, G.; Pozniak, K.; Zabolotny, W.; Larroque, S.; Verger, J.-M.; O’Mullane, M.; Mlynář, Jan; Byszuk, A.; Wojenski, A.

    96-97, October (2015), s. 856-860. ISSN 0920-3796. [Symposium on Fusion Technology 2014(SOFT-28)/28./. San Sebastián, 29.09.2014-03.10.2014] Institutional support: RVO:61389021 Keywords : Soft-X-ray * Gas detector * Tomography * WEST * Tokamak Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.152, year: 2014 http://www. science direct.com/ science /article/pii/S0920379615002215

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

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

    2015-01-01

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

  18. Multi-element silicon detector for x-ray flux measurements

    International Nuclear Information System (INIS)

    A 30-element Si(Li) detector has been fabricated to measure the one-dimensional flux profile of 33 KeV x-rays from a synchrotron radiation beam. The device, which is fabricated from a single 39 mm x 15 mm silicon wafer, is a linear array of 0.9 mm x 7 mm elements with a 1 mm center-to-center spacing. It is 5 mm thick and when operated at room temperature has an average leakage current of 10 nA/element. The x-ray flux in each element is determined by measuring the current with a high quality operational amplifier followed by a current digitizer. This detector is being used to study the use of synchrotron radiation for non-invasive imaging of coronary arteries. The experiment uses the difference in the transmitted flux of a monochromatized x-ray beam above and below the iodine K-edge. Measurements have been made on plastic phantoms and on excised animal hearts with iodinated arteries. The images obtained indicate that a 256-element device with similar properties, but with 0.6 mm element spacing, will make a very effective detector for high-speed medical imaging

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

    Energy Technology Data Exchange (ETDEWEB)

    Fink, Johannes

    2010-01-15

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  2. Application of charge-injection devices for digital X-ray imaging using a planar gas-type X-ray detector

    Science.gov (United States)

    Oh, K.; Shin, J.; Yun, M.; Park, H.; Park, J.; Nam, S.

    2012-07-01

    We have developed a planar gas-type detector, based on a charge injection device; this device can be used for digital X-ray imaging. Previously, in order to obtain X-ray images, a planar gas-type detector utilized a line-scanning module based on a one-dimensional readout system; however, that technology suffered from a limitation such as a long readout time, not suitable for a fluoroscopy or a moving imaging acquisition. In this study, a readout module based on charge-injection devices was used in conjunction with the planar gas-type detector to acquire signals and two-dimensional digital images. In the original design, two orthogonally cross-shaped top electrodes, called X address and Y address, played important roles in transferring and collecting the generated charges using electrical potential. During the optimization process, the shape of these top electrodes was modified into a honeycomb shape to increase the efficacy of charge collection. A mixture of gas and dielectric layers were selected to make an efficient gas-type detector for digital X-ray imaging. From the result, the electrical properties of the detector were investigated and the effectiveness of its geometrical design was proved. Measurements demonstrated the linearity of X-ray detection, and the successful movement and collection of charge using electrical potential. Thus, this modified planar gas-type detector and charge readout module using a charge-injection device made it possible to obtain two-dimensional images without using a scanning mode.

  3. A new generation of detectors for scanning x-ray beam imaging systems

    Science.gov (United States)

    Rommel, J. Martin

    2016-01-01

    Scanning x-ray beam imaging systems were first developed by American Science and Engineering, Inc. (AS&E) in the early 1970s [1]. Since then, these systems have found a wide range of applications in security inspection and non-destructive testing. Large-area detectors are most frequently used to collect backscattered radiation but smaller transmission detectors are also employed for selected applications. Until recently, only two basic detector designs have been used: large scintillator blocks with attached photomultiplier tubes (PMTs) or large-volume light-sealed boxes, lined with scintillating screens and port windows for PMTs. In both cases, the detectors have required considerable depth to provide acceptable light collection efficiency. A new design recently developed by AS&E relies on wavelength shifting fibres (WSF) for light collection. For the first time, this approach enables the construction of thin large-area detectors. Stacking layers of WSF ribbons and scintillating screens in varying combinations enables optimization of the detection efficiency for different applications. Taking separate readings from different layers provides an energy-sensitive signal combination. Energy sensitivity can be improved further by adding filtration between the signal channels. Several prototype configurations have been built and characterized for both backscatter and transmission imaging. A WSF-based detector has been commercialized for a transmission x-ray imaging application.

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

    Science.gov (United States)

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

    2016-06-01

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

  5. A new generation of detectors for scanning x-ray beam imaging systems

    International Nuclear Information System (INIS)

    Scanning x-ray beam imaging systems were first developed by American Science and Engineering, Inc. (AS and E) in the early 1970s [1]. Since then, these systems have found a wide range of applications in security inspection and non-destructive testing. Large-area detectors are most frequently used to collect backscattered radiation but smaller transmission detectors are also employed for selected applications. Until recently, only two basic detector designs have been used: large scintillator blocks with attached photomultiplier tubes (PMTs) or large-volume light-sealed boxes, lined with scintillating screens and port windows for PMTs. In both cases, the detectors have required considerable depth to provide acceptable light collection efficiency. A new design recently developed by AS and E relies on wavelength shifting fibres (WSF) for light collection. For the first time, this approach enables the construction of thin large-area detectors. Stacking layers of WSF ribbons and scintillating screens in varying combinations enables optimization of the detection efficiency for different applications. Taking separate readings from different layers provides an energy-sensitive signal combination. Energy sensitivity can be improved further by adding filtration between the signal channels. Several prototype configurations have been built and characterized for both backscatter and transmission imaging. A WSF-based detector has been commercialized for a transmission x-ray imaging application

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

    DEFF Research Database (Denmark)

    Ejdrup, T.; Lemke, H.T.; Haldrup, Martin Kristoffer; Nielsen, T.N.; Arms, D.A.; Walko, D.A.; Miceli, A.; Landahl, E.C.; Dufresne, E.M.; Nielsen, Martin Meedom

    capability of the gated PILATUS detector to selectively detect the signal from a given X-ray pulse in 24 bunch mode at the APS storage ring is demonstrated. A test experiment performed on polycrystalline organic thin films of [alpha]-perylene illustrates the possibility of reaching an X-ray pulse duration...

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Tina, Adrienne

    2015-08-21

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

  9. Considerations for application of Si(Li) detectors in analyses of sub-keV, ion-induced x rays

    International Nuclear Information System (INIS)

    Spectroscopy of ion-induced x rays is commonly performed using lithium-drifted, silicon detectors, Si(Li), with beryllium windows. Strong absorption of x rays with energies below 1 keV occurs in even the thinnest commercially available beryllium windows and precludes useful analysis of sub-keV x rays. Access to the sub-keV x ray region can be achieved using windowless (WL) and ultra-thin-windowed (UTW) Si(Li) detectors. These detectors have been shown to be useful for spectroscopy of x rays with energies above approximately 200 eV. The properties of such detectors are reviewed with regard to analysis of ion-induced x rays. In particular, considerations of detection efficiency, output linearity, energy resolution, peak shapes, and vacuum requirements are presented. The use of ion excitation for determination of many detector properties serves to demonstrate the usefulness of WL and UTW detectors for the spectroscopy of sub-keV, ion-induced x rays. 23 refs., 4 figs

  10. Measurements of X-rays from Ne recoil ions with a position sensitive detector

    International Nuclear Information System (INIS)

    Measurements of soft X-rays with wavelength 35-47 nm from Ne recoil ions, excited by 24 MeV Cl ions, are reported obtained with a 2.2 m grazing incidence spectrometer. A position sensitive channelplate detector with a two-dimensional wedge and strip readout is used instead of a channeltron, scanning along the Rowland circle. The perfomance of this position sensitive detector is optimized, wavelength calibration procedures are worked out and its efficiency is compared with the scanning channeltron. The detection yield and resolution is measured as a function of the angle of the radiation to the detector normal. An increase by a factor of 12 in the detection efficiency over a spectral region is found for the position sensitive detector compared with a scanning channeltron detector. (orig.)

  11. Si(Li) x-ray detectors with amorphous silicon passivation

    International Nuclear Information System (INIS)

    Lithium-drifted silicon [Si(Li)] detectors with thin lithium n+ contacts and amorphous silicon (α-Si) junction passivation are described. These detectors (7 mm thick, 9 cm2 area) are intended for use in a six element detector array which is designed to measure trace amounts of plutonium in soil samples. Results are given showing a spectral resolution of approx. 400 eV (FWHM) for the 17.8 keV N/sub p/ L x-rays entering through either these detectors. Measurements on the effects of the fractional H2 concentration on the electrical behavior of the α-Si/Si interface are reported. The increase with time in the lithium window thickness when the detectors are stored at room temperature is discussed

  12. The study in photoelectric conversion efficiency of low X-ray energy industry CT detectors

    International Nuclear Information System (INIS)

    Photoelectric conversion efficiency is a important capability parameter for Industry CT Detectors in Low energy. I have analyzed the effect of some common scintillating crystals' parameter such as efficiency, dimension and to Photoelectric conversion efficiency. And compared their Photoelectric conversion efficiency of CsI(Tl) and CdWO4 scintillating crystal detectors through test experiments. It proved that in the Low X-ray energy Industry CT, CsI(Tl) is more suitable than CdWO4 to be material for scintillating crystal detector, and its thickness greatly affect on the detector. It has certain referenced values to optimize the selection and designing dimension of Industry CT system detector Scintillating crystal. (authors)

  13. Investigation of X-ray spectral response of D-T fusion produced neutron irradiated PIPS detectors for plasma X-ray diagnostics

    International Nuclear Information System (INIS)

    This paper describes the fusion-produced neutron irradiation induced changes in the X-ray spectral response of commercially available Passivated Implanted Planar Silicon (PIPS) detectors using the accelerator based D-T generator. After 14.1 MeV neutron irradiation up to a fluence of 3.6× 1010 n/cm2, the energy resolution (i.e. FWHM) of the detectors at room temperature is found to degrade by about 3.8 times that of the pre-irradiated value. From the X-ray spectral characteristics, it has been observed that the room temperature spectral response of PIPS detectors is too poor even at low neutron fluences. Irradiation is also carried out with Am-Be neutron source for studying the effect of scattered neutrons from the reactor walls on the detector performance. Comparative studies of the damage caused by 14.1 MeV neutrons and Am-Be source produced neutrons at the same neutron fluence are carried out by analyzing the irradiated detector characteristics. The degradation in the energy resolution of the detectors is attributed to the radiation induced changes in the detector leakage current. No considerable changes in the full depletion voltage and the effective doping concentration up to the neutron fluence of 3.6× 1010 n/cm2, are observed from the measured C-V characteristics. Partial recovery of the neutron irradiated detector characteristics is discussed

  14. X-ray multi-energy radiography with "scintillator-photodiode" detectors

    CERN Document Server

    Ryzhikov, V D; Grinyov, B V; Lisetskaya, E K; Opolonin, A D; Kozin, D N

    2002-01-01

    For reconstruction of the spatial structure of many-component objects, it is proposed to use multi-radiography with detection of X-ray by combined detector arrays using detectors of ``scintillator-photodiode'' type. A theoretical model has been developed of multi-energy radiography for thickness measurements of multi-layered systems and systems with defects. Experimental studies of the sensitivity, output signal of various inspection systems based on scintillators $ZnSe(Te)$ and $CsI(Tl)$, and object image reconstruction (with organics and non-ogranics materials singled out) have been carried out.

  15. High performance, thermoelectrically cooled X-ray and gamma ray detectors

    International Nuclear Information System (INIS)

    A compact, inexpensive system for high resolution X-ray and gamma ray detection has been developed. A small, cylindrical hybrid circuit includes detector, FET and feedback components mounted on a small thermoelectric cooler. The hybrid mounts to a small enclosure which provides heat sinking and houses the hybrid preamplifier. A novel feedback technique eliminates feedback resistor noise. Resolution with a 7 mm2 silicon-PIN diode for the 5.9 keV 55Fe peak is 250 eV FWHM. Other solid state detectors may be used with the XR-100T electronics to meet the requirements of a wide range of applications. (orig.)

  16. VUV and ultrasoft X-ray diode detectors for tokamak plasmas

    International Nuclear Information System (INIS)

    Ultrasoft X-ray diode (USXRD) arrays have been used on D-IIID and ASDEX to study plasma edge radiation, in the photon energy range from 10 eV to 10 keV. The detectors are extremely useful and versatile due to their simplicity and compactness. Furthermore, absolute quantum efficiencies (QE) of many photocathodes such as vitreous C, Al, Cu CuI, CsI and Au have been measured in recent years. With filter technique, broadband resolution, E/ΔE ≅ 1, is possible. QE comparison of USXRD with semiconductor XRD is also presented to better understand the regions of applicability for each detector. (orig.)

  17. Characterization of Si Hybrid CMOS Detectors for use in the Soft X-ray Band

    OpenAIRE

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

    2013-01-01

    We report on the characterization of four Teledyne Imaging Systems HAWAII Hybrid Si CMOS detectors designed for X-ray detection. Three H1RG detectors were studied along with a specially configured H2RG. Read noise measurements were performed, with the lowest result being 7.1 e- RMS. Interpixel capacitive crosstalk (IPC) was measured for the three H1RGs and for the H2RG. The H1RGs had IPC upper limits of 4.0 - 5.5 % (up & down pixels) and 8.7 - 9.7 % (left & right pixels), indicating a clear a...

  18. Characterization of an x-ray hybrid CMOS detector with low interpixel capacitive crosstalk

    CERN Document Server

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

    2012-01-01

    We present the results of x-ray measurements on a hybrid CMOS detector that uses a H2RG ROIC and a unique bonding structure. The silicon absorber array has a 36{\\mu}m pixel size, and the readout array has a pitch of 18{\\mu}m; but only one readout circuit line is bonded to each 36x36{\\mu}m absorber pixel. This unique bonding structure gives the readout an effective pitch of 36{\\mu}m. We find the increased pitch between readout bonds significantly reduces the interpixel capacitance of the CMOS detector reported by Bongiorno et al. 2010 and Kenter et al. 2005.

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

    OpenAIRE

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

    2016-01-01

    The Speedster-EXD is a new 64x64 pixel, 40 $\\mu$m pixel pitch, 100 $\\mu$m depletion depth hybrid CMOS X-ray detector (HCD) with the capability of reading out only those pixels containing event charge, thus enabling fast effective frame rates. A global charge threshold can be specified, and pixels containing charge above this threshold are flagged and read out. The Speedster detector has also been designed with other advanced in-pixel features to improve performance, including a low-noise, hig...

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

    OpenAIRE

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

    2010-01-01

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

  1. Near room temperature X-ray and Gamma ray spectroscopic detectors for future space experiments

    CERN Document Server

    Yadav, J S; Malkar, J P

    2005-01-01

    New generation Cadmium Telluride (CZT & CdTe) solid state detectors can provide high quantum efficiency with reasonably good energy resolution and can operate at near room temperature; an unique advantage for space experiments. We present here results of our study of small diode detectors as well as large area pixel detectors. Our study is aimed at developing near room temperature hard X-ray spectroscopy detectors for ASTROSAT and other future Indian space science missions.We have studied a Si-PIN detector in the energy range 5 - 60 keV and CZT & CdTe Schottky diode detectors in the energy region 10 - 1330 keV. We have studied large area (64 cm$^2$) CZT pixel detectors with pixel size close to the small CZT detector. We have studied individual pixels as well as CZT detector as a whole (summed over all the 1024 pixels). The energy resolution behaviour of the large area CZT detector is similar to that of small diode detectors in the low energy region. The change in operating temperature from room temper...

  2. X-ray diffuse scattering for evaluation of wide bandgap semiconductor nuclear radiation detectors

    International Nuclear Information System (INIS)

    The crystalline perfection of solid state radiation detectors was examined using triple axis x-ray diffraction. Triple axis techniques provide a means to analyze the origin of diffraction peak broadening: the effects of strain (due to deviations in alloy composition or stoichiometry) and lattice tilts (mosaic structure) can be separated. Cd1-xZnxTe (x∼0.1), HgI2, and GaAs detector materials were studied. In the cases of Cd1-xZnxTe and HgI2 the crystalline properties of detectors with different spectral responses to γ-radiation were determined. Increased mosaicity was universally found to be related to deteriorated detector properties. For Cd1-xZnxTe, detectors with poor performance possessed greater levels of diffuse scatter due to lattice tilts than did high quality detectors. For GaAs, low angle grain boundaries were attributed to impaired detector performance. Additionally, in large HgI2 detectors, deviations from stoichiometry were also related to reduced performance. Interestingly, HgI2 detectors which possessed a sharp spectral response to γ-radiation but also showed polarization were of comparable crystallinity to those detectors which did not exhibit polarization effects. This initial analysis suggests that polarization is related to native point defects or chemical impurities which do not significantly alter the crystallinity of the material. Overall, within a given class of materials, improved detector performance (better spectral response) always correlated with better material quality. (orig.)

  3. Cooled CdZnTe detectors for X-ray astronomy

    CERN Document Server

    Bale, G; Seller, P; Lowe, B

    1999-01-01

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

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

    CERN Document Server

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

    2002-01-01

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

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

    Science.gov (United States)

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

    2015-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-15

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

  7. The Speedster-EXD - A New Event-Triggered Hybrid CMOS X-ray Detector

    Science.gov (United States)

    Griffith, Christopher; Falcone, Abe; Prieskorn, Zach; Burrows, David

    2015-04-01

    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. Hybrid CMOS detectors currently have many advantages over CCDs including lower susceptibility to radiation damage, lower power consumption, and faster read-out time to avoid pile-up. The Speedster-EXD hybrid CMOS detector has many new features that improve upon the previous generation of detectors including two new in-pixel features that reduce noise from known noise sources: (1) a low-noise, high-gain CTIA amplifier to eliminate interpixel capacitance crosstalk and (2) in-pixel CDS subtraction to reduce kTC noise. The most exciting new feature of the Speedster-EXD is an in-pixel comparator that enables read out of only the pixels which contain signal from an x-ray event. The comparator threshold can be set by the user so that only pixels with signal above the set threshold are read out. This comparator feature can increase effective frame rate by orders of magnitude. We present the read noise, dark current, interpixel capacitance, energy resolution, and gain variation measurements of two Speedster-EXD detectors.

  8. Development of a TES-Based Anti-Coincidence Detector for Future X-ray Observatories

    Science.gov (United States)

    Bailey, Catherine

    2011-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

  10. The Dexela 2923 CMOS X-ray detector: A flat panel detector based on CMOS active pixel sensors for medical imaging applications

    OpenAIRE

    Konstantinidis, A. C.; Szafraniec, M. B.; Speller, R.D.; Olivo, A.

    2012-01-01

    Complementary metal-oxide-semiconductors (CMOS) active pixel sensors (APS) have been introduced recently in many scientific applications. This work reports on the performance (in terms of signal and noise transfer) of an X-ray detector that uses a novel CMOS APS which was developed for medical X-ray imaging applications. For a full evaluation of the detector's performance, electro-optical and X-ray characterizations were carried out. The former included measuring read noise, full well capacit...

  11. Analytic fitting and simulation methods for characteristic X-ray peaks from Si-PIN detector

    International Nuclear Information System (INIS)

    A semi-empirical detector response function (DRF) model is established to fit characteristic X-ray peaks recorded in Si-PIN spectra, which is mainly composed of four components: a truncated step function, a Gaussian-shaped full-energy peak, a Gaussian-shaped Si escape peak and an exponential tail. A simple but useful statistical distribution-based analytic method (SDA) is proposed to achieve accurate values of standard deviation for characteristic X-ray peaks. And the values of the model parameters except for the standard deviation are obtained by weighted least-squares fitting of the pulse-height spectra from a number of pure-element samples. A Monte Carlo model is also established to simulate the X-ray measurement setup. The simulated flux spectrum can be transformed by Si-PIN detector response function to real pulse height spectrum as studied in this work. Finally, the fitting result for a copper alloy sample was compared with experimental spectra, and the validity of the present method was demonstrated. (authors)

  12. Unconventional XAS applications in Physical Science using Pixel Array X-ray Detector

    International Nuclear Information System (INIS)

    Fluorescence x-ray yield is a conventional technique which increases sensitivity of x-ray absorption spectroscopy (XAS). Combining high brilliance x-ray sources and state-of-the-art pixel array detector (PAD) opened up unconventional application channels in condensed matter science. PAD is a segmented detector fabricated onto a mono domain single crystal by lithography. Our Ge PAD consists of 10x10 segments with almost 100% packing ratio. The local structure of photo-induced phase transition of Fe(II) spin-crossover complex under visible light irradiation was studied. We find that the coordination symmetry is retained upon the diamagnetic (S=0)↔paramagnetic (S=2) transformation. In the application to high-temperature superconducting (La,Sr)2CuO4 thin film single crystals, the EXAFS results show that the local structure (CuO6 octahedron) is tetragonally deformed in accordance with the epitaxial strain. High-quality data without the effect of substrates were obtained by real-time monitoring segmented fluorescence signals

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

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

    2002-01-01

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

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

    Indian Academy of Sciences (India)

    S S Desai; J N Joshi; A M Shaikh

    2002-10-01

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

  16. Fast Gated Detectors for Ballistic Imaging with Hard X-Rays

    Energy Technology Data Exchange (ETDEWEB)

    Perry, M D; Sefcik, J; Moran, M; Snavely, R

    1998-07-03

    Intense laser (>10{sup 21} W/cm{sup 2}) driven hard x-ray sources offer a new alternative to conventional electron accelerator Bremstrahlung sources. These laser driven sources offer considerable simplicity in design for multiple axis views and have the potential for very high spatial (<0.1 mm) and temporal resolution (<10 psec). The temporal resolution can be converted into increased image contrast by gating out the scattered background radiation and detecting only the ballistic photons transmitted by the object of interest. Currently available hard x-ray (>0.1 MeV) imaging systems are limited to a time resolution greater than {approx}60 nsec. Here, we propose the investigation of new types of imaging x-ray detectors which offer the potential for gate times less than 100 psec at photons energies in the 0.1-8 MeV range. Such detectors would find use in a variety of advanced radiographic applications in DOE'S stockpile Stewardship Program.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2015-10-01

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

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

    CERN Document Server

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

    2016-01-01

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

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

    CERN Document Server

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

    2004-01-01

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

  1. The use of small x-ray detectors for deep space relative navigation

    Science.gov (United States)

    Doyle, Patrick T.; Gebre-Egziabher, Demoz; Sheikh, Suneel I.

    2012-10-01

    Currently, there is considerable interest in developing technologies that will allow the use of high-energy photon measurements from celestial X-ray sources for deep space relative navigation. The impetus for this is to reduce operational costs in the number of envisioned space missions that will require spacecraft to have autonomous, or semiautonomous, navigation capabilities. For missions close to Earth, Global Navigation Satellite Systems (GNSS), such as the U.S. Global Positioning System (GPS), are readily available for use and provide high accuracy navigation solutions that can be used for autonomous vehicle operation. However, for missions far from Earth, currently only a few navigation options exist and most do not allow autonomous operation. While the radio telemetry based solutions with proven high performance such as NASA's Deep Space Network (DSN) can be used for these class of missions, latencies associated with servicing a fleet of vehicles, such as a constellation of communication or science observation spacecraft, may not be compatible with autonomous operations which require timely updates of navigation solutions. Thus, new alternative solutions are sought with DSN-like accuracy. Because of their highly predictable pulsations, pulsars emitting X-radiation are ideal candidates for this task. These stars are ubiquitous celestial sources that can be used to provide time, attitude, range, and range-rate measurements — key parameters for navigation. Laboratory modeling of pulsar signals and operational aspects such as identifying pulsar-spacecraft geometry and performing cooperative observations with data communication are addressed in this paper. Algorithms and simulation tools that will enable designing and analyzing X-ray navigation concepts for a cis-lunar operational scenario are presented. In this situation, a space vehicle with a large-sized X-ray detector will work cooperatively with a number of smaller vehicles with smaller-sized detectors to

  2. X-ray detectors based on Fe doped GaN photoconductors

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Kai; Yao, Changsheng [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, 215123 Suzhou (China); Graduate University of Chinese Academy of Sciences, 19A Yuquanlu, 100049 Beijing (China); Yu, Guohao; Lu, Min [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, 215123 Suzhou (China); Wang, Guo [Peking University, Beijing (China); Peking University Shenzhen Graduate School, Xili Town Nanshan District, 518055 Shenzhen (China); Zhang, Guoguang [China Institute of Atomic Energy, P.O. Box 275-, 102413 Beijing (China)

    2011-06-15

    X-ray detectors based on Fe doped GaN photoconductors have been fabricated. The dark current I{sub d} and photocurrent I{sub p} as a function of bias have been investigated and a large I{sub p}/I{sub d} ratio of 180 at 200 V has been obtained in spite of optical quenching. The physical mechanism of the transient performance of the photoconductor has been studied through fitting the experimental data. The functions of photocurrent versus acceleration voltage and current of the X-ray source have been measured and discussed. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. A spherical drift chamber area detector for X-ray crystallography

    CERN Document Server

    Bolon, C; Lanza, R; Quigley, G; Rich, A

    1979-01-01

    A multiwire proportional chamber system has been built as an area detector for use in X-ray crystallography with Cu K/sub alpha / radiation (1.54AA). The chamber, constructed by Charpak and collaborators at CERN, consists of a 10cm thick spherical interaction region with a radial electric field, a transition from spherical to plane geometry and a 50cm*50cm multiwire proportional chamber and subtends a 90 degrees opening angle. Two dimensional position information is obtained from orthogonal cathode planes using a high speed analog centroid finding technique. Data on spatial and energy resolution as a function of angle and depth of interaction in the spherical drift region using a collimated, pulsed, X-ray source are presented. Ionization loss as a function of drift distance and field and loss due to field shaping grids has also been measured. (6 refs).

  4. Contrast cancellation technique applied to digital x-ray imaging using silicon strip detectors

    International Nuclear Information System (INIS)

    Dual-energy mammographic imaging experimental tests have been performed using a compact dichromatic imaging system based on a conventional x-ray tube, a mosaic crystal, and a 384-strip silicon detector equipped with full-custom electronics with single photon counting capability. For simulating mammal tissue, a three-component phantom, made of Plexiglass, polyethylene, and water, has been used. Images have been collected with three different pairs of x-ray energies: 16-32 keV, 18-36 keV, and 20-40 keV. A Monte Carlo simulation of the experiment has also been carried out using the MCNP-4C transport code. The Alvarez-Macovski algorithm has been applied both to experimental and simulated data to remove the contrast between two of the phantom materials so as to enhance the visibility of the third one

  5. CdTe in photoconductive applications. Fast detector for metrology and X-ray imaging

    International Nuclear Information System (INIS)

    Operating as a photoconductor, the sensitivity and the impulse response of semi-insulating materials greatly depend on the excitation duration compared to electron and hole lifetimes. The requirement of ohmic contact is shortly discussed. Before developing picosecond measurements with integrated autocorrelation system, this paper explains high energy industrial tomographic application with large CdTe detectors (25x15x0.9 mm3). The excitation is typically μs range. X-ray flash radiography, with 10 ns burst, is in an intermediate time domain where excitation is similar to electron life-time. In laser fusion experiment excitation is in the range of 50 ps and we develop photoconductive devices able to study very high speed X-ray emission time behaviour. Thin polycristalline MOCVD CdTe films with picosecond response are suitable to perform optical correlation measurements of single shot pulses with a very large bandwidth (- 50 GHz)

  6. Development and evaluation of a portable amorphous silicon flat-panel x-ray detector

    Science.gov (United States)

    Watanabe, Minoru; Mochizuki, Chiori; Kameshima, Toshio; Yamazaki, Tatsuya; Court, Laurence; Hayashida, Shinsuke; Morishita, Masakazu; Ohta, Shin-ichi

    2001-06-01

    The design, development and evaluation of a portable x-ray detector are described. The completed detector has a pixel pitch of 100 micrometers , an active imaging area of 22.5 x 27.5 cm2 (9 x 11 inch2), package outer dimensions of 32.5 x 32.5 cm2, a thickness of only 20 mm, and a weight of around 2.8 kg. A number of significant advances in the design and production processes were needed to produce such a compact detector with such a small pixel pitch, while maintaining the image quality achieved a current detector (CXDI-22) which has a 160 mm pixel pitch. These include the development of a low power readout IC, advances in detector packaging design, concentrating on lightweight and strong components, and redesign of the pixel structure to improve the fill-factor. A comparison is made of the imaging characteristics of this new detector with the CXDI-22 detector, and it is shown that the new detector demonstrates improved CTF, and NEQ. The new detector is also shown to demonstrate superior performance in a contrast-detail phantom evaluation. This new detector should be useful for limb and joint examinations as it offers high spatial resolution, combined with the same freedom in positioning provided by conventional screen-film cassettes.

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

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

    2016-03-01

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

  9. Optimum spectroscopic performance from CZT gamma- and X-ray detectors with pad and strip segmentation

    CERN Document Server

    Shor, A; Mardor, I

    1999-01-01

    We describe a method for obtaining optimum spectroscopic performance from CZT gamma- and X-ray detectors with segmented readout. This method allows to circumvent the effects of incomplete charge collection and to obtain energy resolution approaching the limitation due to detector and electronic noise. It is insensitive to hole trapping over most of the detector volume, while a modest amount of electron trapping can be tolerated. The method requires segmentation of the positive electrode. Signals from the common electrode, taken in coincidence with those of the segmented positive electrode, provide a measure of the depth of interaction. A distinct correlation profile exists between the signals of the segmented element and the common electrode. These profiles can be linearized to yield very sharp energy lines with high photopeak efficiency. Additional cuts can be made to improve peak-to-valley ratio, with small loss in efficiency. We present measurements taken with CZT detectors with pad segmentation. Illuminat...

  10. Neutron Radiation Shielding For The NIF Streaked X-Ray Detector (SXD) Diagnostic

    International Nuclear Information System (INIS)

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is preparing for the National Ignition Campaign (NIC) scheduled in 2010. The NIC is comprised of several ''tuning'' physics subcampaigns leading up to a demonstration of Inertial Confinement Fusion (ICF) ignition. In some of these experiments, time-resolved x-ray imaging of the imploding capsule may be required to measure capsule trajectory (shock timing) or x-ray ''bang-time''. A capsule fueled with pure tritium (T) instead of a deutriun-tritium (DT) mixture is thought to offer useful physics surrogacy, with reduced yields of up to 5e14 neutrons. These measurements will require the use of the NIF streak x-ray detector (SXD). The resulting prompt neutron fluence at the planned SXD location (∼1.7 m from the target) would be ∼1.4e9/cm2. Previous measurements suggest the onset of significant background at a neutron fluence of ∼ 1e8/cm2. The radiation damage and operational upsets which starts at ∼1e8 rad-Si/sec must be factored into an integrated experimental campaign plan. Monte Carlo analyses were performed to predict the neutron and gamma/x-ray fluences and radiation doses for the proposed diagnostic configuration. A possible shielding configuration is proposed to mitigate radiation effects. The primary component of this shielding is an 80 cm thickness of Polyethylene (PE) between target chamber center (TCC) and the SXD diagnostic. Additionally, 6-8 cm of PE around the detector provide from the large number of neutrons that scatter off the inside of the target chamber. This proposed shielding configuration reduces the high-energy neutron fluence at the SXD by approximately a factor ∼50

  11. Neutron Radiation Shielding For The NIF Streaked X-Ray Detector (SXD) Diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Song, P; Holder, J; Young, B; Kalantar, D; Eder, D; Kimbrough, J

    2006-11-02

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is preparing for the National Ignition Campaign (NIC) scheduled in 2010. The NIC is comprised of several ''tuning'' physics subcampaigns leading up to a demonstration of Inertial Confinement Fusion (ICF) ignition. In some of these experiments, time-resolved x-ray imaging of the imploding capsule may be required to measure capsule trajectory (shock timing) or x-ray ''bang-time''. A capsule fueled with pure tritium (T) instead of a deutriun-tritium (DT) mixture is thought to offer useful physics surrogacy, with reduced yields of up to 5e14 neutrons. These measurements will require the use of the NIF streak x-ray detector (SXD). The resulting prompt neutron fluence at the planned SXD location ({approx}1.7 m from the target) would be {approx}1.4e9/cm{sup 2}. Previous measurements suggest the onset of significant background at a neutron fluence of {approx} 1e8/cm{sup 2}. The radiation damage and operational upsets which starts at {approx}1e8 rad-Si/sec must be factored into an integrated experimental campaign plan. Monte Carlo analyses were performed to predict the neutron and gamma/x-ray fluences and radiation doses for the proposed diagnostic configuration. A possible shielding configuration is proposed to mitigate radiation effects. The primary component of this shielding is an 80 cm thickness of Polyethylene (PE) between target chamber center (TCC) and the SXD diagnostic. Additionally, 6-8 cm of PE around the detector provide from the large number of neutrons that scatter off the inside of the target chamber. This proposed shielding configuration reduces the high-energy neutron fluence at the SXD by approximately a factor {approx}50.

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

    Data.gov (United States)

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

  13. Characterization of HgI2 single crystals and detectors by x-ray rocking curve analysis and x-ray reflection topography

    International Nuclear Information System (INIS)

    An attempt has been made to establish a correlation between the results of x-ray rocking curves and x-ray reflection topographs for vapor grown HgI2, single crystals. X-ray rocking curves were obtained by double crystal spectroscopy with Si as the first crystal and topographs were produced using the Berg-Barrett technique with an asymmetrically cut Si-disperser. The crystals were evaluated at different stages of detector preparation, i.e., cutting, polishing, etching, and deposition of contact. Multiple diffraction peaks could be observed as being indicative of small angle grain boundaries of up to 2/degree/. Definite nonuniformities on virgin single crystals as well as on detector crystals were observed by both methods. The crystal surface quality as assessed by these methods were used as a criterion to verify detector performance rating. No drastic improvement of surface quality on space grown crystals was indicated by these techniques. Efforts have also been devoted to determine intrinsic full width at half maximum of HgI2 crystal for the crystallographic direction studied. 16 refs., 22 figs

  14. Characterization of HgI/sub 2/ single crystals and detectors by x-ray rocking curve analysis and x-ray reflection topography

    Energy Technology Data Exchange (ETDEWEB)

    Ostrom, R.; Keller, L.; Wagner, N.J.; Schieber, M.M.; Ortale, C.; van den Berg, L.; Schnepple, W.F.

    1987-01-01

    An attempt has been made to establish a correlation between the results of x-ray rocking curves and x-ray reflection topographs for vapor grown HgI/sub 2/, single crystals. X-ray rocking curves were obtained by double crystal spectroscopy with Si as the first crystal and topographs were produced using the Berg-Barrett technique with an asymmetrically cut Si-disperser. The crystals were evaluated at different stages of detector preparation, i.e., cutting, polishing, etching, and deposition of contact. Multiple diffraction peaks could be observed as being indicative of small angle grain boundaries of up to 2/degree/. Definite nonuniformities on virgin single crystals as well as on detector crystals were observed by both methods. The crystal surface quality as assessed by these methods were used as a criterion to verify detector performance rating. No drastic improvement of surface quality on space grown crystals was indicated by these techniques. Efforts have also been devoted to determine intrinsic full width at half maximum of HgI/sub 2/ crystal for the crystallographic direction studied. 16 refs., 22 figs.

  15. Review of hybrid pixel detector readout ASICs for spectroscopic X-ray imaging

    International Nuclear Information System (INIS)

    Semiconductor detector readout chips with pulse processing electronics have made possible spectroscopic X-ray imaging, bringing an improvement in the overall image quality and, in the case of medical imaging, a reduction in the X-ray dose delivered to the patient. In this contribution we review the state of the art in semiconductor-detector readout ASICs for spectroscopic X-ray imaging with emphasis on hybrid pixel detector technology. We discuss how some of the key challenges of the technology (such as dealing with high fluxes, maintaining spectral fidelity, power consumption density) are addressed by the various ASICs. In order to understand the fundamental limits of the technology, the physics of the interaction of radiation with the semiconductor detector and the process of signal induction in the input electrodes of the readout circuit are described. Simulations of the process of signal induction are presented that reveal the importance of making use of the small pixel effect to minimize the impact of the slow motion of holes and hole trapping in the induced signal in high-Z sensor materials. This can contribute to preserve fidelity in the measured spectrum with relatively short values of the shaper peaking time. Simulations also show, on the other hand, the distortion in the energy spectrum due to charge sharing and fluorescence photons when the pixel pitch is decreased. However, using recent measurements from the Medipix3 ASIC, we demonstrate that the spectroscopic information contained in the incoming photon beam can be recovered by the implementation in hardware of an algorithm whereby the signal from a single photon is reconstructed and allocated to the pixel with the largest deposition

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-15

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

  18. Review of hybrid pixel detector readout ASICs for spectroscopic X-ray imaging

    Science.gov (United States)

    Ballabriga, R.; Alozy, J.; Campbell, M.; Frojdh, E.; Heijne, E. H. M.; Koenig, T.; Llopart, X.; Marchal, J.; Pennicard, D.; Poikela, T.; Tlustos, L.; Valerio, P.; Wong, W.; Zuber, M.

    2016-01-01

    Semiconductor detector readout chips with pulse processing electronics have made possible spectroscopic X-ray imaging, bringing an improvement in the overall image quality and, in the case of medical imaging, a reduction in the X-ray dose delivered to the patient. In this contribution we review the state of the art in semiconductor-detector readout ASICs for spectroscopic X-ray imaging with emphasis on hybrid pixel detector technology. We discuss how some of the key challenges of the technology (such as dealing with high fluxes, maintaining spectral fidelity, power consumption density) are addressed by the various ASICs. In order to understand the fundamental limits of the technology, the physics of the interaction of radiation with the semiconductor detector and the process of signal induction in the input electrodes of the readout circuit are described. Simulations of the process of signal induction are presented that reveal the importance of making use of the small pixel effect to minimize the impact of the slow motion of holes and hole trapping in the induced signal in high-Z sensor materials. This can contribute to preserve fidelity in the measured spectrum with relatively short values of the shaper peaking time. Simulations also show, on the other hand, the distortion in the energy spectrum due to charge sharing and fluorescence photons when the pixel pitch is decreased. However, using recent measurements from the Medipix3 ASIC, we demonstrate that the spectroscopic information contained in the incoming photon beam can be recovered by the implementation in hardware of an algorithm whereby the signal from a single photon is reconstructed and allocated to the pixel with the largest deposition.

  19. Performance of a chip for hybrid pixel detectors with two counters for X-ray imaging

    International Nuclear Information System (INIS)

    A semiconductor hybrid pixel detector for dynamic X-ray imaging is developed. The detector, called DIXI, consists of a semiconductor sensor mounted onto a readout chip. A detector module with a 500 μm silicon sensor is currently being assembled with the use of anisotropic conductive film as interconnection between the sensor and the readout chip. The basic building block of the detector is 1 cm2 in size and consists of 992 square pixel cells arranged in 31 columns and 32 rows. The pixels have a side of 270 μm. The readout chip is capable of performing photon counting and has an externally adjustable threshold. The readout chip has been characterised by charge injection in the absence of a sensor. The threshold dispersion is measured to 365 e- for hole collection. Even if the chip was not originally designed for electron collection a threshold dispersion of 1650 e- has been achieved. Two counters are implemented in every single pixel cell and the threshold can be changed from one image to the next in order to select different parts of the X-ray spectrum

  20. A multi-channel monolithic Ge detector system for fluorescence x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bucher, J.J.; Allen, P.G.; Edelstein, N.M.; Shuh, D.K. [Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.; Madden, N.W.; Cork, C.; Luke, P.; Pehl, D.; Malone, D. [Lawrence Berkeley National Lab., CA (United States). Engineering Div.

    1995-03-01

    Construction and performance of a monolithic quad-pixel Ge detector for fluorescence x-ray absorption spectroscopy (XAS) at synchrotron radiation sources are described. The detector semiconductor element has an active surface area of 4.0 cm{sup 2} which is electrically separated into four 1.0 cm{sup 2} pixels, with little interfacial dead volume. Spatial response of the array shows that cross-talk between adjacent pixels is < 10% for 5.9 keV photons that fall within 0.5 mm of the pixel boundaries. The detector electronics system uses pre-amplifiers built at LBNL with commercial Tennelec Model TC 244 amplifiers. Using an {sup 55}Fe test source (MnK{sub {alpha}}, 5.9 keV), energy resolution of better than 200 eV is achieved with a 4 {mu}sec peaking time. At 0.5 {mu}sec peaking time, pulse pileup results in a 75% throughput efficiency for an incoming count rate of 100 kHz. Initial XAS fluoresncece measurements at the beamline 4 wiggler end stations at SSRL show that the detector system has several advantages over commercial x-ray spectrometers for low-concentration counting.

  1. Characterization of Si Hybrid CMOS Detectors for use in the Soft X-ray Band

    Science.gov (United States)

    Prieskorn, Zachary; Griffith, C.; Bongiorno, S.; Falcone, A.; Burrows, D. N.

    2014-01-01

    In a joint program between Penn State University and Teledyne Imaging Sensors a soft X-ray detector based on the HAWAII Hybrid Si CMOS detector (HCD) has been developed. HCDs could potentially be the optimum detectors for the next generation of X-ray missions, especially those with focused optics and/or large effective area. These innovative detectors are active pixel sensors (APS) which allow a pixel to be read through individual in-pixel electronics, without the need to transfer charge across many pixels, in contrast to a CCD. They are made by bonding a Si absorbing layer to a pixelated CMOS readout, allowing the two layers to be optimized independently. The advantages of this design compared to CCDs are high speed timing 100 μs in full imaging mode), a flexible windowed readout to reduce pile-up, dramatically improved radiation hardness and resistance to micrometeoroid damage, and reduced power requirements. We present recent measurements of energy resolution, read noise, inter-pixel crosstalk, quantum efficiency, and dark current for four of these devices.

  2. Development of a shutterless continuous rotation method using an X-ray CMOS detector for protein crystallography

    OpenAIRE

    Hasegawa, Kazuya; Hirata, Kunio; Shimizu, Tetsuya; Shimizu, Nobutaka; Hikima, Takaaki; Baba, Seiki; Kumasaka, Takashi; Yamamoto, Masaki

    2009-01-01

    A new shutterless continuous rotation method using an X-ray complementary metal-oxide semiconductor (CMOS) detector has been developed for high-speed, precise data collection in protein crystallography. The principle of operation and the basic performance of the X-ray CMOS detector (Hamamatsu Photonics KK C10158DK) have been shown to be appropriate to the shutterless continuous rotation method. The data quality of the continuous rotation method is comparable to that of the conventional oscill...

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lauf, Thomas

    2011-04-28

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

  5. ZnO nanowires in polycarbonate membrane as a high resolution X-ray detector (a Geant4 simulation)

    International Nuclear Information System (INIS)

    The capability of polycarbonate cladded ZnO nanowires as scintillating optical fibers, in the presence of the 10 keV X-ray is simulated using the Geant4 Monte Carlo simulation code. The simulated results show that using millions of scintillating fibers in a 1 mm2 area, which are packed together in a polycarbonate membrane, have additional light guiding role that reduces the scattering of the X-ray generated optical photons inside the detector. This new low-cost technique can provide a higher spatial resolution X-ray imager with sharper edges at the object boundaries in comparison to a single crystal scintillating macro detectors

  6. Usefulness of an energy-binned photon-counting x-ray detector for dental panoramic radiographs

    Science.gov (United States)

    Fukui, Tatsumasa; Katsumata, Akitoshi; Ogawa, Koichi; Fujiwara, Shuu

    2015-03-01

    A newly developed dental panoramic radiography system is equipped with a photon-counting semiconductor detector. This photon-counting detector acquires transparent X-ray beams by dividing them into several energy bands. We developed a method to identify dental materials in the patient's teeth by means of the X-ray energy analysis of panoramic radiographs. We tested various dental materials including gold alloy, dental amalgam, dental cement, and titanium. The results of this study suggest that X-ray energy scattergram analysis could be used to identify a range of dental materials in a patient's panoramic radiograph.

  7. High altitude balloon flights of position sensitive CdZnTe detectors for high energy X-ray astronomy

    International Nuclear Information System (INIS)

    Cadmium Zinc Telluride (CZT) is a semiconductor detector well suited for high energy X-ray astronomy. The High-Energy X-ray Imaging Spectrometer (HEXIS) program is developing this technology for use in a hard X-ray all-sky survey and as a focal plane imager for missions such as FARXITE and Constellation X. We have designed a novel electrode geometry that improves interaction localization and depth of interaction determination. The HEXIS program has flown two high altitude balloon payloads from Ft. Summer, NM to investigate background properties and shielding effects on a position sensitive CZT detector in the energy range of 20-350 keV

  8. The application of photoconductive detectors to the measurement of x-ray production in laser produced plasmas

    International Nuclear Information System (INIS)

    Photoconductive detectors (PCDs) offer an attractive alternative for the measurement of pulsed x-rays from laser produced plasmas. These devices are fast (FWHM ∼100 ps), sensitive and simple to use. We have used InP, GaAs, and Type IIa diamond as PCDs to measure x-rays emission from 100 eV to 100 keV. Specifically, we have used these detectors to measure total radiation yields, corona temperatures, and hot electron generated x-rays from laser produced plasmas. 5 refs., 4 figs

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

    Science.gov (United States)

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

    2016-03-01

    JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional hybrid pixel detector for photon science applications at free-electron lasers and synchrotron light sources. The JUNGFRAU 0.4 prototype presented here is specifically geared towards low-noise performance and hence soft X-ray detection. The design, geometry and readout architecture of JUNGFRAU 0.4 correspond to those of other JUNGFRAU pixel detectors, which are charge-integrating detectors with 75 µm × 75 µm pixels. Main characteristics of JUNGFRAU 0.4 are its fixed gain and r.m.s. noise of as low as 27 e(-) electronic noise charge (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

  10. Refinement of position resolution in two-dimensional X-ray detector based on μ-PIC gaseous detector

    International Nuclear Information System (INIS)

    We have successfully refined the position resolution of a two-dimensional X-ray photon-counting detector based on the micro-pixel gas chamber (μ-PIC) by measuring the charge distribution of an X-ray interaction without the use of analog-to-digital converters (ADCs). By updating the logic of the Field Programmable Gate Arrays (FPGAs) included in the data acquisition system, we were able to acquire the pulse widths, or time-above-threshold of the μ-PIC signals, by measuring both the leading and trailing edges of the digital signals. By using the measured widths to estimate the peak of the charge distribution, the position resolution of our detector was improved to σ=93.3±2.8μm from a value of σ=229.5±6.8μm found using the FPGA logic of the previous system. This represents an improvement of nearly 60%.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-11-09

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

  12. Characteristics and quality test of X-ray with CZT detector

    International Nuclear Information System (INIS)

    The study examines the use of direct measurements of x-ray spectra for testing the quality of x-ray beam by using a peltier-cooled CZT detector under different conditions. The typical calibration of the spectrometry system shows that the energy resolution of the system is 1,2 keV at 122 keV of 57 Co. The utilization CZT based spectrometer for assessing the quality of x-ray machine on its spectra show that the CZT could accurately measure the spectra at various kVp, m As and filtration, except at the kVp greater than 140 and m As higher than 2 without added filtration. A comparison of CZT with the field instruments showed that there is a reasonable agreement between the Keithley and CZT at lower energies regardless of filtration however at high energies there is a large difference.In contrast the discrepancy between the CZT and Nero increased at lower photon energies particularly for high filtration

  13. Development of an ultra-fast X-ray camera using hybrid pixel detectors

    International Nuclear Information System (INIS)

    The aim of the project whose work described in this thesis is part, was to design a high-speed X-ray camera using hybrid pixels applied to biomedical imaging and for material science. As a matter of fact the hybrid pixel technology meets the requirements of these two research fields, particularly by providing energy selection and low dose imaging capabilities. In this thesis, high frame rate X-ray imaging based on the XPAD3-S photons counting chip is presented. Within a collaboration between CPPM, ESRF and SOLEIL, three XPAD3 cameras were built. Two of them are being operated at the beamline of the ESRF and SOLEIL synchrotron facilities and the third one is embedded in the PIXSCAN II irradiation setup of CPPM. The XPAD3 camera is a large surface X-ray detector composed of eight detection modules of seven XPAD3-S chips each with a high-speed data acquisition system. The readout architecture of the camera is based on the PCI Express interface and on programmable FPGA chips. The camera achieves a readout speed of 240 images/s, with maximum number of images limited by the RAM memory of the acquisition PC. The performance of the device was characterized by carrying out several high speed imaging experiments using the PIXSCAN II irradiation setup described in the last chapter of this thesis. (author)

  14. Collecting data in the home laboratory: evolution of X-ray sources, detectors and working practices

    International Nuclear Information System (INIS)

    Recent developments in X-ray crystallographic hardware related to structural biology research are presented and discussed. While the majority of macromolecular X-ray data are currently collected using highly efficient beamlines at an ever-increasing number of synchrotrons, there is still a need for high-performance reliable systems for in-house experiments. In addition to crystal screening and optimization of data-collection parameters before a synchrotron trip, the home system allows the collection of data as soon as the crystals are produced to obtain the solution of novel structures, especially by the molecular-replacement method, and is invaluable in achieving the quick turnover that is often required for ligand-binding studies in the pharmaceutical industry. There has been a continuous evolution of X-ray sources, detectors and software developed for in-house use in recent years and a diverse range of tools for structural biology laboratories are available. An overview of the main directions of these developments and examples of specific solutions available to the macromolecular crystallography community are presented in this paper, showing that data collection ‘at home’ is still an attractive proposition complementing the use of synchrotron beamlines

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

    CERN Document Server

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

    2014-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-07-01

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

  17. A computer-controlled x-ray imaging scanner using a kinestatic charge detector

    Science.gov (United States)

    Wagenaar, Douglas J.; DiBianca, Frank A.; Tenney, Charles R.; Vance, Joseph E.; Reed, Mark S. C.; Wilson, Donald W.; Dollas, Apostolos; McDaniel, David L.; Granfors, Paul; Petrick, Scott

    1990-02-01

    A prototype scanning imaging system which employs a kinestatic charge detector (KCD) and is under the control of a VAXstation II/GPX computer is described. The operating principles and advantages of the KCD method are reviewed. The detector is a 256-channel ionization drift chamber which creates a two-dimensional x-ray projection image by scanning the detector past the object of interest. The details of the drift chamber design, the signal collection electrodes (channels), and the Frisch grid geometry are given. Also described are the scanning gantry design, computer-controlled drive motor circuit, and safety features. The data acquisition system for the capture of a 1 M byte digital image is presented. This includes amplification, filtration, analog-to-digital conversion, data buffering, and transfer to the VAXstation II computer. The image processing and display techniques specific to the KCD are outlined and the first two-dimensional image taken with this system is presented.

  18. Detector for imaging of explosions: present status and future prospects with higher energy X-rays

    CERN Document Server

    Aulchenko, V M; Shekhtman, L I; Ten, K A; Tolochko, B P; Zhogin, I L; Zhulanov, V V

    2008-01-01

    The detector for imaging of explosions (DIMEX) is in operation at the synchrotron radiation (SR) beam-line at VEPP-3 electron ring at Budker INP since 2002. DIMEX is based on one-coordinate gas ionization chamber filled with Xe-CO2(3:1) mixture at 7atm, and active Frisch-grid made of Gas Electron Multiplier (GEM). The detector has spatial resolution of ~0.2mm and dynamic range of ~100 that allows to realize the precision of signal measurement at a percent level. The frame rate can be tuned up to 8 MHz (125 ns per image) and up to 32 images can be stored in one shot. At present DIMEX is used with the X-ray beam from 2T wiggler that has ~20 keV average energy. Future possibility to install similar detector at the SR beam-line at VEPP-4 electron ring is discussed.

  19. X-ray imaging using single photon processing with semiconductor pixel detectors

    International Nuclear Information System (INIS)

    More than 10 years experience with semiconductor pixel detectors for vertex detection in high-energy physics experiments together with the steady progress in CMOS technology opened the way for the development of single photon processing pixel detectors for various applications including medical X-ray imaging. The state of the art of such pixel devices consists of pixel dimensions as small as 55x55 μm2, electronic noise per pixel 100 e- rms, signal-to-noise discrimination levels around 1000 e- with a spread 50 e- and a dynamic range up to 32 bits/pixel. Moreover, the high granularity of hybrid pixel detectors makes it possible to probe inhomogeneities of the attached semiconductor sensor

  20. X-ray imaging using single photon processing with semiconductor pixel detectors

    CERN Document Server

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

    2003-01-01

    More than 10 years experience with semiconductor pixel detectors for vertex detection in high energy physics experiments together with the steady progress in CMOS technology opened the way for the development of single photon processing pixel detectors for various applications including medical X-ray imaging. The state of the art of such pixel devices consists of pixel dimensions as small as 55x55 um2, electronic noise per pixel <100 e- rms, signal-to-noise discrimination levels around 1000 e- with a spread <50 e- and a dynamic range up to 32 bits per pixel. Moreover, the high granularity of hybrid pixel detectors makes it possible to probe inhomogeneities of the attached semiconductor sensor.

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

    CERN Document Server

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

    2012-01-01

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

  2. X-ray color imaging with 3D sensitive voxel detector

    International Nuclear Information System (INIS)

    X-ray imaging is today widely used in a broad range of applications. Nevertheless some limitations are represented by the inability to distinguish between a thick layer of low Z material and a thin layer of high Z material, and by the beam hardening, where the incident X-ray spectrum is modified as the beam traverses the sample. Such effects cause problems in many applications (e.g. CT reconstruction) generating artifacts and worsening the spatial resolution. This work presents a new technique allowing spectral sensitivity using a new 3D voxel detector based on the Timepix pixel detector. The device is designed as a layered stack of several Timepix sensors. The readout chip is thinned down to reduce the amount of insensitive absorbing material. Every single layers in the stack act as a filter, i.e. each stack layer visualizes a different part of the spectrum attenuated by the object giving further information about the object composition. The comparison of attenuation levels observed in different detector layers can be used to estimate the extent of the beam hardening effect in the imaged object and thus point out differences in the material composition.

  3. Optimizing detector thickness in dual-shot dual-energy x-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Woon; Kam, Soohwa; Youn, Hanbean; Kim, Ho Kyung [Pusan National University, Busan (Korea, Republic of)

    2015-05-15

    As a result, there exist apparent limitations in the conventional two-dimensional (2D) radiography: One is that the contrast between the structure of interest and the background in a radiograph is much less than the intrinsic subject contrast (i.e. the difference between their attenuation coefficients; Another is that the superimposed anatomical structures in the 2D radiograph results in an anatomical background clutter that may decrease the conspicuity of subtle underlying features. These limitations in spatial and material discrimination are important motivations for the recent development of 3D (e.g. tomosynthesis) and dual energy imaging (DEI) systems. DEI technique uses a combination of two images obtained at two different energies in successive x-ray exposures by rapidly switching the kilovolage (kV) applied to the x-ray tube. Commercial DEI systems usually employ a 'single' of flat-panel detector (FPD) to obtain two different kV images. However, we have a doubt in the use of the same detector for acquiring two different projections for the low- and high-kV setups because it is typically known that there exists an optimal detector thickness regarding specific imaging tasks or energies used.

  4. Optimizing detector thickness in dual-shot dual-energy x-ray imaging

    International Nuclear Information System (INIS)

    As a result, there exist apparent limitations in the conventional two-dimensional (2D) radiography: One is that the contrast between the structure of interest and the background in a radiograph is much less than the intrinsic subject contrast (i.e. the difference between their attenuation coefficients; Another is that the superimposed anatomical structures in the 2D radiograph results in an anatomical background clutter that may decrease the conspicuity of subtle underlying features. These limitations in spatial and material discrimination are important motivations for the recent development of 3D (e.g. tomosynthesis) and dual energy imaging (DEI) systems. DEI technique uses a combination of two images obtained at two different energies in successive x-ray exposures by rapidly switching the kilovolage (kV) applied to the x-ray tube. Commercial DEI systems usually employ a 'single' of flat-panel detector (FPD) to obtain two different kV images. However, we have a doubt in the use of the same detector for acquiring two different projections for the low- and high-kV setups because it is typically known that there exists an optimal detector thickness regarding specific imaging tasks or energies used

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

    Science.gov (United States)

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

    2016-03-01

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

  6. Digital signal processing techniques for image reconstruction with x ray position sensitive detectors

    International Nuclear Information System (INIS)

    The present work describes the acquisition and processing platform for an X ray imaging system based on position sensitive avalanche photo-diodes. The major application fields of the proposed imaging detector are nuclear and particle physics as well as medical imaging. The radiation detector consists of an HV biased Gas Electron Multiplier (GEM) on a scintillation media (typically a rare gas with CF4 mixture) optically attached to a bi-dimensional position sensitive APD. The X ray radiation enters a gas tight beryllium window inducing an electron avalanche process in the vicinity of the GEM holes. The localized avalanches produce light in the visible region that is collected by the PS-APD. This device has 4 signal outputs which are fully digitized upon each trigger of an individual event through a 4 channel 8-bit, 200 MSample/s, PCI acquisition module. The position and energy of the event is then obtained from these signal through digital signal processing techniques. This digital processing approach allows for the near-optimal filtering design according to the effective noise sources in the system hence maximizing the SNR. Other advantages of a fully digital processing platform include rise time or pulse shape discrimination and real time image distortion correction. The imaging detector is currently being assembled along with configuration and software development of the 4-channel acquisition platform. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-05-12

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

  8. A versatile television X-ray detector and image processing system

    International Nuclear Information System (INIS)

    A high resolution, software configurable TV area detector has been developed for use in a wide range of applications including synchrotron radiation research. The X-ray sensitivity extends from 100 eV to 30 keV and rates between 100 and 1012 events/s can be measured. Active areas from 4 to 80 mm diameter or square can be selected and easily changed. The image acquisition, processing, and integration are under software control and can be optimized for each experiment. (orig.)

  9. Mobility-lifetime product in epitaxial GaAs X-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sun, G.C. [GESEC R and D, Universite Pierre et Marie Curie, Bat.11, 140 rue de Lourmel, 75015 Paris (France)]. E-mail: guocsun@ccr.jussieu.fr; Zazoui, M. [LPMC, Faculte des Sciences et Techniques-Mohammedia, B.P. 146 Bd Hassan II, Mohammedia, Maroc (Morocco); Talbi, N. [Faculte des Sciences, Universite de Gabes, Route de Medenine, 6029 Gabes (Tunisia); Khirouni, K. [Faculte des Sciences, Universite de Gabes, Route de Medenine, 6029 Gabes (Tunisia); Bourgoin, J.C. [GESEC R and D, Universite Pierre et Marie Curie, Bat.11, 140 rue de Lourmel, 75015 Paris (France)

    2007-04-01

    Self-supported thick (200-500 {mu}m), non-intentionally doped, epitaxial GaAs layers are good candidates for X-ray imaging for the following reasons. Their electronic properties are homogeneous over large areas, they can be grown at low cost, the technology to realize pixel detectors of various size is standard, the defect concentration is low and the fluorescence yield is small. Here, we characterize the defects present in the material and evaluate the mobility-lifetime product, using Deep Level Transient Spectroscopy combined with current-voltage and charge collection measurements.

  10. The speedster-EXD - A new event-triggered hybrid CMOS x-ray detector

    OpenAIRE

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

    2014-01-01

    We present preliminary characterization of the Speedster-EXD, a new event driven hybrid CMOS detector (HCD) developed in collaboration with Penn State University and Teledyne Imaging Systems. HCDs have advantages over CCDs including lower susceptibility to radiation damage, lower power consumption, and faster read-out time to avoid pile-up. They are deeply depleted and able to detect x-rays down to approximately 0.1 keV. The Speedster-EXD has additional in-pixel features compared to previousl...

  11. Characterization of an x-ray hybrid CMOS detector with low interpixel capacitive crosstalk

    OpenAIRE

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

    2012-01-01

    We present the results of x-ray measurements on a hybrid CMOS detector that uses a H2RG ROIC and a unique bonding structure. The silicon absorber array has a 36{\\mu}m pixel size, and the readout array has a pitch of 18{\\mu}m; but only one readout circuit line is bonded to each 36x36{\\mu}m absorber pixel. This unique bonding structure gives the readout an effective pitch of 36{\\mu}m. We find the increased pitch between readout bonds significantly reduces the interpixel capacitance of the CMOS ...

  12. The data acquisition system for the Leeds Infirmary MWPC X-ray imaging detector

    International Nuclear Information System (INIS)

    An electronic system is described which is designed to acquire and process data from a MWPC X-ray imaging detector. Two dimensional information from the chamber is obtained by using cathode plane delay-line readout. A single crate CAMAC assembly is used as the chamber-computer interface. The use of control source units for the delay line scalers and TV display driver functions together with an intermediate memory in the crate allows input data rates up to 1MHz and TV display facilities without constant computer refreshing. (author)

  13. Time and Energy Measurement Electronics for Silicon Drift Detector Aimed for X-ray Pulsar Navigation

    OpenAIRE

    Chen, Er-Lei; Feng, Chang-Qing; Ye, Chun-Feng; Liu, Shu-Bin; Jin, Dong-Dong; Lian, Jian; HU, HUI-JUN

    2016-01-01

    A readout electronic with high time and energy resolution performance is designed for the SDD (Silicon Drift Detector) signals readout, which is aimed for X-ray pulsar based navigation (XNAV). For time measurement, the input signal is fed into a fast shaping and Constant Fraction Discrimination (CFD) circuit, and then be digitalized by a Time-to-Digital Converter (TDC) implemented in an Field Programmable Gate Array (FPGA), which is designed with a bin size of 2.5 ns. For energy measurement, ...

  14. Statistical reconstruction for x-ray computed tomography using energy-integrating detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lasio, Giovanni M [Division of Medical Physics, Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA 23298 (United States); Whiting, Bruce R [Department of Radiology, Washington University, St Louis, MO 63130 (United States); Williamson, Jeffrey F [Division of Medical Physics, Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA 23298 (United States)

    2007-04-21

    Statistical image reconstruction (SR) algorithms have the potential to significantly reduce x-ray CT image artefacts because they use a more accurate model than conventional filtered backprojection and can incorporate effects such as noise, incomplete data and nonlinear detector response. Most SR algorithms assume that the CT detectors are photon-counting devices and generate Poisson-distributed signals. However, actual CT detectors integrate energy from the x-ray beam and exhibit compound Poisson-distributed signal statistics. This study presents the first assessment of the impact on image quality of the resultant mismatch between the detector and signal statistics models assumed by the sinogram data model and the reconstruction algorithm. A 2D CT projection simulator was created to generate synthetic polyenergetic transmission data assuming (i) photon-counting with simple Poisson-distributed signals and (ii) energy-weighted detection with compound Poisson-distributed signals. An alternating minimization (AM) algorithm was used to reconstruct images from the data models (i) and (ii) for a typical abdominal scan protocol with incident particle fluence levels ranging from 10{sup 5} to 1.6 x 10{sup 6} photons/detector. The images reconstructed from data models (i) and (ii) were compared by visual inspection and image-quality figures of merit. The reconstructed image quality degraded significantly when the means were mismatched from the assumed model. However, if the signal means are appropriately modified, images from data models (i) and (ii) did not differ significantly even when SNR is very low. While data-mean mismatches characteristic of the difference between particle-fluence and energy-fluence transmission can cause significant streaking and cupping artefacts, the mismatch between the actual and assumed CT detector signal statistics did not significantly degrade image quality once systematic data means mismatches were corrected.

  15. Characterization of Si hybrid CMOS detectors for use in the soft X-ray band

    International Nuclear Information System (INIS)

    We report on the characterization of four Teledyne Imaging Systems HAWAII Hybrid Si CMOS detectors designed for X-ray detection. Three H1RG detectors were studied along with a specially configured H2RG. Read noise measurements were performed, with the lowest result being 7.1 e− RMS. Interpixel capacitive crosstalk (IPC) was measured for the three H1RGs and for the H2RG. The H1RGs had IPC upper limits of 4.0–5.5% (up and down pixels) and 8.7–9.7% (left and right pixels), indicating a clear asymmetry. Energy resolution is reported for two X-ray lines, 1.5 and 5.9 keV, at multiple temperatures between 150 and 210 K. The best resolution measured at 5.9 keV was 250 eV (4.2%) at 150 K, with IPC contributing significantly to this measured energy distribution. The H2RG, with a unique configuration designed to decrease the capacitive coupling between ROIC pixels, had an IPC of 1.8±1.0% indicating a dramatic improvement in IPC with no measurable asymmetry. We also measured dark current as a function of temperature for each detector. For the detector with the lowest dark current, at 150 K, we measured a dark current of 0.020±0.001 (e− s−1 pixel−1). There is also a consistent break in the fit to the dark current data for each detector. Above 180 K, all the data can be fit by the product of a power law in temperature and an exponential. Below 180 K the dark current decreases more slowly; a shallow power law or constant must be added to each fit, indicating a different form of dark current is dominant in this temperature regime. Dark current figures of merit at 293 K are estimated from the fit for each detector

  16. Optimization of <= 200 um pitch CZT detectors for future high-resolution X-ray instrumentation in astrophysics

    CERN Document Server

    Zajczyk, Anna; Dowkontt, Paul; Guo, Qingzhen; Kislat, Fabian; Krawczynski, Henric; De Geronimo, Gianluigi; Li, Shaorui; Beilicke, Matthias

    2015-01-01

    Cadmium Zinc Telluride and Cadmium Telluride are the detector materials of choice for the detection of X-rays in the X-ray energy band E >= 5keV with excellent spatial and spectral resolution and without cryogenic cooling. Owing to recent breakthroughs in grazing incidence mirror technology, next-generation hard X-ray telescopes will achieve angular resolution between 5 and 10 arc seconds - about an order of magnitude better than that of the NuSTAR hard X-ray telescope. As a consequence, the next generation of X-ray telescopes will require pixelated X-ray detectors with pixels on a grid with a lattice constant of <= 250um. Additional detector requirements include a low energy threshold of less than 5keV and an energy resolution of less than one keV. The science drivers for a high angular-resolution X-ray mission include studies and measurements of black hole spins, the cosmic evolution of super-massive black holes, active galactic nuclei feedback, and the behaviour of matter at very high densities. In this...

  17. Heel effect adaptive flat field correction of digital x-ray detectors

    International Nuclear Information System (INIS)

    Purpose: Anode heel effect renders large-scale background nonuniformities in digital radiographs. Conventional offset/gain calibration is performed at mono source-to-image distance (SID), and disregards the SID-dependent characteristic of heel effect. It results in a residual nonuniform background in the corrected radiographs when the SID settings for calibration and correction differ. In this work, the authors develop a robust and efficient computational method for digital x-ray detector gain correction adapted to SID-variant heel effect, without resorting to physical filters, phantoms, complicated heel effect models, or multiple-SID calibration and interpolation.Methods: The authors present the Duo-SID projection correction method. In our approach, conventional offset/gain calibrations are performed only twice, at the minimum and maximum SIDs of the system in typical clinical use. A fast iterative separation algorithm is devised to extract the detector gain and basis heel patterns from the min/max SID calibrations. The resultant detector gain is independent of SID, while the basis heel patterns are parameterized by the min- and max-SID. The heel pattern at any SID is obtained from the min-SID basis heel pattern via projection imaging principles. The system gain desired at a specific acquisition SID is then constructed using the projected heel pattern and detector gain map.Results: The method was evaluated for flat field and anatomical phantom image corrections. It demonstrated promising improvements over interpolation and conventional gain calibration/correction methods, lowering their correction errors by approximately 70% and 80%, respectively. The separation algorithm was able to extract the detector gain and heel patterns with less than 2% error, and the Duo-SID corrected images showed perceptually appealing uniform background across the detector.Conclusions: The Duo-SID correction method has substantially improved on conventional offset/gain corrections for

  18. Heel effect adaptive flat field correction of digital x-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yongjian [X-ray Products, Varian Medical Systems Inc., Liverpool, New York 13088 (United States); Wang, Jue [Department of Mathematics, Union College, Schenectady, New York 12308 (United States)

    2013-08-15

    Purpose: Anode heel effect renders large-scale background nonuniformities in digital radiographs. Conventional offset/gain calibration is performed at mono source-to-image distance (SID), and disregards the SID-dependent characteristic of heel effect. It results in a residual nonuniform background in the corrected radiographs when the SID settings for calibration and correction differ. In this work, the authors develop a robust and efficient computational method for digital x-ray detector gain correction adapted to SID-variant heel effect, without resorting to physical filters, phantoms, complicated heel effect models, or multiple-SID calibration and interpolation.Methods: The authors present the Duo-SID projection correction method. In our approach, conventional offset/gain calibrations are performed only twice, at the minimum and maximum SIDs of the system in typical clinical use. A fast iterative separation algorithm is devised to extract the detector gain and basis heel patterns from the min/max SID calibrations. The resultant detector gain is independent of SID, while the basis heel patterns are parameterized by the min- and max-SID. The heel pattern at any SID is obtained from the min-SID basis heel pattern via projection imaging principles. The system gain desired at a specific acquisition SID is then constructed using the projected heel pattern and detector gain map.Results: The method was evaluated for flat field and anatomical phantom image corrections. It demonstrated promising improvements over interpolation and conventional gain calibration/correction methods, lowering their correction errors by approximately 70% and 80%, respectively. The separation algorithm was able to extract the detector gain and heel patterns with less than 2% error, and the Duo-SID corrected images showed perceptually appealing uniform background across the detector.Conclusions: The Duo-SID correction method has substantially improved on conventional offset/gain corrections for

  19. X-ray fluorescence analysis in environmental radiological surveillance using HPGe detectors

    International Nuclear Information System (INIS)

    X-ray fluorescence (XRF) has been proven to be a valuable tool for determining trace quantities of heavy metals, such as uranium and lead, in different types of samples. The present paper demonstrates the applicability of XRF spectrometry to measure the concentrations of these heavy metals in samples from natural ore and soil. The values of uranium concentrations in rock from the Pena Blanca uranium ore, in Chihuahua, Mexico, were calculated for the purpose of precertifying the rock powders samples. The comparison with other techniques, such as inductively coupled plasma atomic emission spectrometry, atomic absorption spectrometry, alpha spectrometry and electron microscopy, was used to complete the precertification process, so that the sample powders may be used as secondary standards. The source-sample-detector geometry and the incident angle are the most important factors for obtaining low detection limits. The selected system uses a 57Co source of about 0.1 mCi to excite the K X-rays from uranium and lead. X-rays were recorded on a CANBERRA HPGe coaxial detector. The comparative results for two incident angles (90 deg and 180 deg ) performed previously by other authors show that the best geometry is the backscattering geometry. In the present paper, using EGS4 code system with Monte Carlo simulation, it was possible to determine the location and distribution of background produced by the Compton edge in the optimized geometry. This procedure allowed to find the minimum detectable concentration of uranium and lead, which was experimentally calculated using standards. The possibility of performing in vivo measurements rapidly and easily, as well as the factors affecting accuracy and the minimum detectable concentration in several samples are also discussed

  20. Measuring the X-ray quantum efficiency of a hybrid CMOS detector with 55Fe

    Science.gov (United States)

    Bongiorno, S. D.; Falcone, A. D.; Prieskorn, Z.; Griffith, C.; Burrows, D. N.

    2015-06-01

    Charge coupled devices (CCDs) are currently the workhorse focal plane arrays operating aboard many orbiting astrophysics X-ray telescopes, e.g. Chandra, XMM-Newton, Swift, and Suzaku. In order to meet the count rate, power, and mission duration requirements defined by next-generation X-ray telescopes, future detectors will need to be read out faster, consume less power, and be more resistant to radiation and micrometeoroid damage than current-generation devices. The hybrid CMOS detector (HCD), a type of active pixel sensor, is currently being developed to meet these requirements. With a design architecture that involves bump bonding two semiconductor substrates together at the pixel level, these devices exhibit both the high read speed and low power consumption of CMOS readout circuitry and the high quantum efficiency (QE) of a deeply depleted silicon absorber. These devices are expected to exhibit the same excellent, high-energy quantum efficiency (QE) as deep-depletion CCDs (QE > 0.9 at 6 keV), while at the same time exhibiting superior readout flexibility, power consumption, and radiation hardness than CCDs. In this work we present a QE model for a Teledyne Imaging Sensors HyViSI HCD, which predicts QE=96% at 55Fe source energies (5.89 and 6.49 keV). We then present a QE measurement of the modeled device at the same energies, which shows QE=97±5% and is in good agreement with the model.

  1. Complete optical stack modeling for CMOS-based medical x-ray detectors

    Science.gov (United States)

    Zyazin, Alexander S.; Peters, Inge M.

    2015-03-01

    We have developed a simulation tool for modeling the performance of CMOS-based medical x-ray detectors, based on the Monte Carlo toolkit GEANT4. Following the Fujita-Lubberts-Swank approach recently reported by Star-Lack et al., we calculate modulation transfer function MTF(f), noise power spectrum NPS(f) and detective quantum efficiency DQE(f) curves. The complete optical stack is modeled, including scintillator, fiber optic plate (FOP), optical adhesive and CMOS image sensor. For critical parts of the stack, detailed models have been developed, taking into account their respective microstructure. This includes two different scintillator types: Gd2O2S:Tb (GOS) and CsI:Tl. The granular structure of the former is modeled using anisotropic Mie scattering. The columnar structure of the latter is introduced into calculations directly, using the parameterization capabilities of GEANT4. The underlying homogeneous CsI layer is also incorporated into the model as well as the optional reflective layer on top of the scintillator screen or the protective polymer top coat. The FOP is modeled as an array of hexagonal bundles of fibers. The simulated CMOS stack consists of layers of Si3N4 and SiO2 on top of a silicon pixel array. The model is validated against measurements of various test detector structures, using different x-ray spectra (RQA5 and RQA-M2), showing good match between calculated and measured MTF(f) and DQE(f) curves.

  2. Characterization of Si Hybrid CMOS Detectors for use in the Soft X-ray Band

    CERN Document Server

    Prieskorn, Zachary; Bongiorno, Stephen D; Falcone, Abraham D; Burrows, David N

    2013-01-01

    We report on the characterization of four Teledyne Imaging Systems HAWAII Hybrid Si CMOS detectors designed for X-ray detection. Three H1RG detectors were studied along with a specially configured H2RG. Read noise measurements were performed, with the lowest result being 7.1 e- RMS. Interpixel capacitive crosstalk (IPC) was measured for the three H1RGs and for the H2RG. The H1RGs had IPC upper limits of 4.0 - 5.5 % (up & down pixels) and 8.7 - 9.7 % (left & right pixels), indicating a clear asymmetry. Energy resolution is reported for two X-ray lines, 1.5 & 5.9 keV, at multiple temperatures between 150 - 210 K. The best resolution measured at 5.9 keV was 250 eV (4.2 %) at 150 K, with IPC contributing significantly to this measured energy distribution. The H2RG, with a unique configuration designed to decrease the capacitive coupling between ROIC pixels, had an IPC of 1.8 +/- 1.0 % indicating a dramatic improvement in IPC with no measurable asymmetry. We also measured dark current as a function of ...

  3. Diffraction of multilayer gratings and zone plates in the x-ray region using the Born approximation

    International Nuclear Information System (INIS)

    New devices combining the Bragg reflection from periodic multilayer structures with Fraunhofer or Fresnel diffraction arising from lateral patterning of the multilayer are now available for x-ray optics. Using Green's-function method, the authors establish an integral equation for the scattered amplitude that is valid in the framework of both Fraunhofer and Fresnel diffraction. The scattered amplitude is given in the first and the second Born approximations for multilayer mirrors, laminar and sawtooth-profile multilayer gratings, and linear multilayer zone plates. The main diffractive properties of these devices are deduced. The efficiencies are computed in the first and/or in the second Born approximation and are compared with efficiencies obtained from a rigorous electromagnetic theory when they are available. 18 refs., 10 figs., 1 tab

  4. Characterization of X-ray polycapillary optics by LiF crystal radiation detectors through confocal fluorescence microscopy

    Science.gov (United States)

    Bonfigli, Francesca; Hampai, Dariush; Dabagov, Sultan B.; Montereali, Rosa Maria

    2016-08-01

    Solid-state radiation imaging detectors based on photoluminescent colour centres in lithium fluoride (LiF) crystals have been successfully tested for both advanced 2D and 3D characterizations of X-ray polycapillary optics by a table-top laboratory system. Polycapillary optics can control X-ray beams propagation and allows obtaining quasi-parallel beam (half-lens) or focused beams (full-lens). The combination of a fine-focused micro X-ray tube and a polycapillary lens can provide the high intensity radiation fluxes that are necessary for high resolution X-ray imaging. In this paper we present novel results about advanced characterization of these complex optics by 2D as well as 3D confocal laser fluorescence microscopy of X-ray irradiated LiF crystal detectors. Two dimensional high spatial resolution images on a wide field of view of transmitted X-rays through a semi-lens and 3D direct inspection of the coloured volumes produced in LiF crystals by both focused and parallel X-ray beam transmitted by a full and a semi-lens, respectively, as well as their 3D reconstructions were obtained. The results show that the photoluminescent colour centres volume in LiF crystals combined with an optical sectioning reading system provide information about tomography of transmitted X-ray beams by policapillary optics in a single exposure process. For the first time, the use of LiF crystal plates as versatile radiation imaging luminescent detectors have been used to characterize the operation of polycapillary optics as X-ray lens, in focusing and parallel mode.

  5. Design and image-quality performance of high resolution CMOS-based X-ray imaging detectors for digital mammography

    International Nuclear Information System (INIS)

    In digital X-ray imaging systems, X-ray imaging detectors based on scintillating screens with electronic devices such as charge-coupled devices (CCDs), thin-film transistors (TFT), complementary metal oxide semiconductor (CMOS) flat panel imagers have been introduced for general radiography, dental, mammography and non-destructive testing (NDT) applications. Recently, a large-area CMOS active-pixel sensor (APS) in combination with scintillation films has been widely used in a variety of digital X-ray imaging applications. We employed a scintillator-based CMOS APS image sensor for high-resolution mammography. In this work, both powder-type Gd2O2S:Tb and a columnar structured CsI:Tl scintillation screens with various thicknesses were fabricated and used as materials to convert X-ray into visible light. These scintillating screens were directly coupled to a CMOS flat panel imager with a 25 × 50 mm2 active area and a 48 μm pixel pitch for high spatial resolution acquisition. We used a W/Al mammographic X-ray source with a 30 kVp energy condition. The imaging characterization of the X-ray detector was measured and analyzed in terms of linearity in incident X-ray dose, modulation transfer function (MTF), noise-power spectrum (NPS) and detective quantum efficiency (DQE).

  6. Design and image-quality performance of high resolution CMOS-based X-ray imaging detectors for digital mammography

    Science.gov (United States)

    Cha, B. K.; Kim, J. Y.; Kim, Y. J.; Yun, S.; Cho, G.; Kim, H. K.; Seo, C.-W.; Jeon, S.; Huh, Y.

    2012-04-01

    In digital X-ray imaging systems, X-ray imaging detectors based on scintillating screens with electronic devices such as charge-coupled devices (CCDs), thin-film transistors (TFT), complementary metal oxide semiconductor (CMOS) flat panel imagers have been introduced for general radiography, dental, mammography and non-destructive testing (NDT) applications. Recently, a large-area CMOS active-pixel sensor (APS) in combination with scintillation films has been widely used in a variety of digital X-ray imaging applications. We employed a scintillator-based CMOS APS image sensor for high-resolution mammography. In this work, both powder-type Gd2O2S:Tb and a columnar structured CsI:Tl scintillation screens with various thicknesses were fabricated and used as materials to convert X-ray into visible light. These scintillating screens were directly coupled to a CMOS flat panel imager with a 25 × 50 mm2 active area and a 48 μm pixel pitch for high spatial resolution acquisition. We used a W/Al mammographic X-ray source with a 30 kVp energy condition. The imaging characterization of the X-ray detector was measured and analyzed in terms of linearity in incident X-ray dose, modulation transfer function (MTF), noise-power spectrum (NPS) and detective quantum efficiency (DQE).

  7. X-ray micro-CT scanner for small animal imaging based on Timepix detector technology

    Energy Technology Data Exchange (ETDEWEB)

    Dudak, Jan, E-mail: jan.dudak@utef.cvut.cz [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, 128 00 Prague 2 (Czech Republic); Faculty of Biomedical Engineering, Czech Technical University in Prague, Nam. Sitna 3105, 272 00 Kladno (Czech Republic); Zemlicka, Jan; Krejci, Frantisek; Polansky, Stepan; Jakubek, Jan [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horska 3a/22, 128 00 Prague 2 (Czech Republic); Mrzilkova, Jana; Patzelt, Matej; Trnka, Jan [Third Faculty of Medicine, Charles University in Prague, Ruska 87, 100 00 Prague (Czech Republic)

    2015-02-11

    We describe a newly developed compact micro-CT scanner with rotating gantry equipped with a Timepix Quad hybrid pixel semiconductor detector and a micro-focus X-ray tube providing spatial resolution down to 30 µm. The resolving power of the device in relation to soft tissue sensitivity is demonstrated using a tissue-equivalent phantom and different types of biological samples. The results demonstrate that the use of noiseless particle counting detectors is a promising way to achieve sufficient soft tissue contrast even without any contrast agents. - Highlights: • We developed a new micro-CT scanner for small animal imaging. • Application of Timepix technology to obtain enhanced soft tissue contrast. • Spatial resolution below 30 µm achieved. • Performance demonstrated using a tissue equivalent phantom and biological samples.

  8. X-ray micro-CT scanner for small animal imaging based on Timepix detector technology

    International Nuclear Information System (INIS)

    We describe a newly developed compact micro-CT scanner with rotating gantry equipped with a Timepix Quad hybrid pixel semiconductor detector and a micro-focus X-ray tube providing spatial resolution down to 30 µm. The resolving power of the device in relation to soft tissue sensitivity is demonstrated using a tissue-equivalent phantom and different types of biological samples. The results demonstrate that the use of noiseless particle counting detectors is a promising way to achieve sufficient soft tissue contrast even without any contrast agents. - Highlights: • We developed a new micro-CT scanner for small animal imaging. • Application of Timepix technology to obtain enhanced soft tissue contrast. • Spatial resolution below 30 µm achieved. • Performance demonstrated using a tissue equivalent phantom and biological samples

  9. High-resolution detectors for imaging and spectroscopy at ultraviolet and soft X-ray wavelengths

    Science.gov (United States)

    Timothy, J. G.; Morgan, J. S.; Slater, D. C.

    1988-01-01

    The Multi-Anode Microchannel Arrays (MAMAs) are a family of pulse-counting imaging array detectors designed specifically for astrophysical investigations in space. The MAMAs have a number of unique performance characteristics which make them particularly suitable for imaging and spectroscopy at ultraviolet and soft X-ray wavelengths. First, they employ 'solar blind' photocathodes eliminating the 'red leak' problem associated with solid state arrays such as the CCDs. Second, they operate with zero readout noise, yielding photon-statistics limited signals. Third, they utilize a random readout technique and can determine both the location of a detected photon and also its arrival time to an accuracy of the order of 100 ns. This paper gives an overview of the construction, mode of operation, and performance characteristics of the MAMA detectors and describes the current status of the development program.

  10. A new gated x-ray detector for the Orion laser facility

    Science.gov (United States)

    Clark, David D.; Aragonez, Robert; Archuleta, Thomas; Fatherley, Valerie; Hsu, Albert; Jorgenson, Justin; Mares, Danielle; Oertel, John; Oades, Kevin; Kemshall, Paul; Thomas, Phillip; Young, Trevor; Pederson, Neal

    2012-10-01

    Gated X-Ray Detectors (GXD) are considered the work-horse target diagnostic of the laser based inertial confinement fusion (ICF) program. Recently, Los Alamos National Laboratory (LANL) has constructed three new GXDs for the Orion laser facility at the Atomic Weapons Establishment (AWE) in the United Kingdom. What sets these three new instruments apart from what has previously been constructed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is: improvements in detector head microwave transmission lines, solid state embedded hard drive and updated control software, and lighter air box design and other incremental mechanical improvements. In this paper we will present the latest GXD design enhancements and sample calibration data taken on the Trident laser facility at Los Alamos National Laboratory using the newly constructed instruments.

  11. A New Gated X-Ray Detector for the Orion Laser Facility

    Energy Technology Data Exchange (ETDEWEB)

    Clark, David D. [Los Alamos National Laboratory; Aragonez, Robert J. [Los Alamos National Laboratory; Archuleta, Thomas N. [Los Alamos National Laboratory; Fatherley, Valerie E. [Los Alamos National Laboratory; Hsu, Albert H. [Los Alamos National Laboratory; Jorgenson, H. J. [Los Alamos National Laboratory; Mares, Danielle [Los Alamos National Laboratory; Oertel, John A. [Los Alamos National Laboratory; Oades, Kevin [Atomic Weapons Establishment; Kemshall, Paul [Atomic Weapons Establishment; Thomas, Philip [Atomic Weapons Establishment; Young, Trevor [Atomic Weapons Establishment; Pederson, Neal [VI Control Systems

    2012-08-08

    Gated X-Ray Detectors (GXD) are considered the work-horse target diagnostic of the laser based inertial confinement fusion (ICF) program. Recently, Los Alamos National Laboratory (LANL) has constructed three new GXDs for the Orion laser facility at the Atomic Weapons Establishment (AWE) in the United Kingdom. What sets these three new instruments apart from the what has previously been constructed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is: improvements in detector head microwave transmission lines, solid state embedded hard drive and updated control software, and lighter air box design and other incremental mechanical improvements. In this paper we will present the latest GXD design enhancements and sample calibration data taken on the Trident laser facility at Los Alamos National Laboratory using the newly constructed instruments.

  12. 2D x-ray imaging using a micro-pattern gas detector 'micro pixel chamber (μ-PIC)'

    International Nuclear Information System (INIS)

    The micro-pattern gas detector (MPGD) has a fine electrode structure, and it can obtain much higher positional resolution compared to that of the conventional gas detector based on the multi-wire proportional chamber. The 'Micro Pixel Chamber (μ-PIC)' is a new MPGD developed at Kyoto University. It has been applied not only to X-ray crystallographic analysis, but also particle and nuclear physics. In the present study, some experiments were conducted in order to evaluate the capability of μ-PIC in X-ray analysis. The gas gain of 3000 and linearity up to 200 kcps were obtained. Effect of parallax was examined, showing the image distortion within the theoretical estimate. Small angle X-ray scattering experiment using a collagen sample was also conducted, having demonstrated good X-ray imaging performance of μ-PIC. (author)

  13. Flat panel X-ray detector with reduced internal scattering for improved attenuation accuracy and dynamic range

    Science.gov (United States)

    Smith, Peter D.; Claytor, Thomas N.; Berry, Phillip C.; Hills, Charles R.

    2010-10-12

    An x-ray detector is disclosed that has had all unnecessary material removed from the x-ray beam path, and all of the remaining material in the beam path made as light and as low in atomic number as possible. The resulting detector is essentially transparent to x-rays and, thus, has greatly reduced internal scatter. The result of this is that x-ray attenuation data measured for the object under examination are much more accurate and have an increased dynamic range. The benefits of this improvement are that beam hardening corrections can be made accurately, that computed tomography reconstructions can be used for quantitative determination of material properties including density and atomic number, and that lower exposures may be possible as a result of the increased dynamic range.

  14. X-ray flux from filtered arrays of detectors without unfolding

    International Nuclear Information System (INIS)

    A simple computational method is proposed for estimating the time-dependent flux F[ΔE](t) of an x-ray spectrum S(E,t) over domain [ΔE] from data Dk(t)(k=1,...,N) obtained by an N-channel array of filtered detectors. It is assumed that the data are related to the spectrum by a discrete, inhomogeneous, first-kind Fredholm integral equation Dk=∫S(E,t)Rk(E)dE, where Rk(E) is the known response function for each detector channel of the diagnostic. The proposed method constructs a spectral sensitivity HLS(E) for the diagnostic array as a linear combination Σk=1NakRk(E) of the responses, where the coefficients ak are obtained by a least-squares criterion plus a constraint. The ak values, once determined, apply as long as the responses are valid. The flux estimate is then simply FLS(t)=Σk=1NakDk(t), without a spectral unfold of the data. The method is useful for quick analyses of time-dependent data, for comparisons with other flux-measuring diagnostics, and for the experimental design of filtered-detector arrays. The method is applied to a five-channel array of filtered photoemissive x-ray detectors [G. A. Chandler et al., Rev. Sci. Instrum. 70, 561 (1999)], used for z-pinch measurements at the Z-accelerator facility [R. B. Spielman et al., Phys. Plasmas 5, 2105 (1998)]. Comparisons with unfold results are made, and a first-order analysis of error propagation into FLS(t) is presented

  15. The ^{55}Fe X-ray Energy Response of Mercury Cadmium Telluride Near-Infrared Detector Arrays

    CERN Document Server

    Fox, Ori D; Wen, Yiting; Foltz, Roger D; Hill, Robert J; Kimble, Randy A; Malumuth, Eliot; Rauscher, Bernard J

    2009-01-01

    A technique involving ^{55}Fe X-rays provides a straightforward method to measure the response of a detector. The detector's response can lead directly to a calculation of the conversion gain (e^- ADU^{-1}), as well as aid detector design and performance studies. We calibrate the ^{55}Fe X-ray energy response and pair production energy of HgCdTe using 8 HST WFC3 1.7 \\micron flight grade detectors. The results show that each K$\\alpha$ X-ray generates 2273 \\pm 137 electrons, which corresponds to a pair-production energy of 2.61 \\pm 0.16 eV. The uncertainties are dominated by our knowledge of the conversion gain. In future studies, we plan to eliminate this uncertainty by directly measuring conversion gain at very low light levels.

  16. Comparison of lens- and fiber-coupled CCD detectors for X-ray computed tomography

    OpenAIRE

    Uesugi, K.; Hoshino, M.; Yagi, N

    2010-01-01

    X-ray imaging detectors with an identical phosphor and a CCD chip but employing lens- and fiber-coupling between them have been compared. These are designed for X-ray imaging experiments, especially computed tomography, at the medium-length beamline at the SPring-8 synchrotron radiation facility. It was found that the transmittance of light to the CCD is about four times higher in the fiber-coupled detector. The uniformity of response in the lens-coupled detector has a global shading of up to...

  17. The effect of elastically scattered protons on the energy resolution of x-ray detectors in PIXE measurements

    International Nuclear Information System (INIS)

    Extensive use has been made of particle-induced X-ray emission (PIXE) analysis over the past several years. The optimisation of its detection sensitivity calls for the judicious selection of several parameters including, inter alia, the beam energy used and the X-ray window thickness. Thin windows are required in order to be able to detect the light elements whose X-ray energies are so low that they are heavily attenuated by any absorber material between the target and the detector. The choice of beam energy is dependent on the respective cross sections for X-ray production for elements of interest, the related background generated, as well as the associated beam energy degradation in the targets. These considerations often lead to a state where protons, elastically, scattered from the target, have sufficient energy to penetrate the window and enter the X-ray detector. The extent to which such protons and their related secondary electron production affect the energy resolution of an intrinsic germanium X-ray detector is demonstrated for a proton beam energy range from 2,1 to 3,5 MeV with a window thickness equivalent to the range of a 2,5 MeV proton

  18. Dose distribution around a needle-like anode X-ray tube: Dye-film vs. planar thermoluminescent detectors

    International Nuclear Information System (INIS)

    The dosimetry around the X-ray tube with a needle-like anode (NAXT), developed at the Inst. of Nuclear Studies, for interstitial brachytherapy has been performed using (1) dye films (Gafchromic XR-T), (2) large-area thermoluminescent (TL) detectors - prepared either by gluing TL powder onto thin Al foil (so-called planar detectors with spatial resolution of 0.1 mm) and (3) miniature (2 mm diameter and 0.5 mm thick) TL detectors. The measurements were performed in following geometries. (1) Needle inside a PMMA cylinder - the planar TL detector mounted on the surface of the cylinder. (2) Needle inside a thick block of PMMA and TL detector mounted vertically 7 mm from needle axis. TL detectors were read with the planar (2D) thermoluminescence reader, developed at IFJ, with a sensitive CCD (charge couple device) camera. Gafchromic films were evaluated with a system based on Agfa Arcus 1200 scanner and calibrated with X-rays (35 kV) filtered with 0.03 mm Mo and with Co-60 photons. The intensity distribution of TL light on the planar detector was calibrated in terms of absorbed dose to water, using 137Cs gamma-rays. TL planar detectors seem to be a promising tool for 2D dosimetry of miniature X-ray sources. Obtained results for TLDs and Gafchromic films seem to be comparable but differences have been found. Both methods are useful for measurements of dose distribution around the NAXT X-rays source. (authors)

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

  20. Non-Gaussian noise in x-ray and γ-ray detectors

    Science.gov (United States)

    Chen, Liying; Barrett, Harrison H.

    2005-04-01

    Image statistics are usually modeled as Poisson in γ-ray imaging and as Gaussian in x-ray imaging. In nuclear medicine, event-driven detectors analyze the pulses from every absorbed gamma photon individually; the resulting images rigorously obey Poisson statistics but are approximately Gaussian when the mean number of counts per pixel is large. With integrating detectors, as in digital radiography, each x-ray photon makes a contribution to the image proportional to its pulse height. One pixel senses many photons in long exposures, so the image statistics approach Gaussian by the central limit theorem (CLT). If the exposure time is short enough, however, each pixel will usually respond to no more than one photon, and we can separate individual photons for position estimation. Integrating detectors are therefore event-driven when we use many short-exposure frames rather than one long exposure. In intermediate exposures, the number of photons in one pixel is too small to invoke CLT and apply Gaussian statistics, yet too large to identify individual photons and apply Poisson statistics. In this paper, we analyze the image quality in this intermediate case. Image quality is defined for detection tasks performed by the ideal observer. Because the frames in a data set are independent of each other, the probability density function (PDF) of the whole data set is a product of the frame PDFs. The log-likelihood ratio λ of the ideal observer is thus a sum across the frames and has Gaussian statistics even with non-Gaussian images. We compare the ideal observer's performance with the Hotelling observer's performance under this approximation. A data-thresholding technique to improve Hotelling observer's performance is also discussed.

  1. Development of a fast pixel array detector for use in microsecond time-resolved x-ray diffraction

    International Nuclear Information System (INIS)

    A large-area pixel x-ray detector is being developed to collect eight successive frames of wide dynamic range two-dimensional images at 200kHz rates. Such a detector, in conjunction with a synchrotron radiation x-ray source, will enable time-resolved x-ray studies of proteins and other materials on time scales which have previously been inaccessible. The detector will consist of an array of fully-depleted 150 micron square diodes connected to a CMOS integrated electronics layer with solder bump-bonding. During each framing period, the current resulting from the x-rays stopped in the diodes is integrated in the electronics layer, and then stored in one of eight storage capacitors underneath the pixel. After the last frame, the capacitors are read out at standard data transmission rates. The detector has been designed for a well-depth of at least 10,000 x-rays (at 20keV), and a noise level of one x-ray. Ultimately, the authors intend to construct a detector with over one million pixels (1024 by 1024). They present the results of their development effort and various features of the design. The electronics design is discussed, with special attention to the performance requirements. The choice and design of the detective diodes, as they relate to x-ray stopping power and charge collection, are presented. An analysis of various methods of bump bonding is also presented. Finally, the authors discuss the possible need for a radiation-blocking layer, to be placed between the electronics and the detective layer, and various methods they have pursued in the construction of such a layer

  2. Modeling quantum noise of phosphors used in medical X-ray imaging detectors

    CERN Document Server

    Kalivas, N; Cavouras, D; Costaridou, L; Nomicos, C D; Panayiotakis, G S

    1999-01-01

    The noise properties of the granular phosphor screens, which are utilized in X-ray imaging detectors, are studied in terms of the quantum noise transfer function (QNTF). An analytical model, taking into account the effect of K-characteristic X-rays reabsorption within the phosphor material and the optical properties of the phosphor, was developed. The optical properties of the phosphor material required by the model were obtained from literature, except for the optical diffusion length (sigma) that was determined by data fitting and was found to be 26 cm sup 2 /g. The deviation between theoretical and experimental data is sigma depended. Specifically for sigma=26 cm sup 2 /g and sigma=25 cm sup 2 /g the respective deviations between experimental and predicted results were 0.698% and -1.597%. However for relative differences in sigma more than 15% from the value 26 cm sup 2 /g, the corresponding deviations exceed by 6 times the value of 0.698%. The model was tested via comparison to experimental results obtain...

  3. High resolution X-ray detector for synchrotron-based microtomography

    CERN Document Server

    Stampanoni, M; Wyss, P; Abela, R; Patterson, B; Hunt, S; Vermeulen, D; Rueegsegger, P

    2002-01-01

    Synchrotron-based microtomographic devices are powerful, non-destructive, high-resolution research tools. Highly brilliant and coherent X-rays extend the traditional absorption imaging techniques and enable edge-enhanced and phase-sensitive measurements. At the Materials Science Beamline MS of the Swiss Light Source (SLS), the X-ray microtomographic device is now operative. A high performance detector based on a scintillating screen optically coupled to a CCD camera has been developed and tested. Different configurations are available, covering a field of view ranging from 715x715 mu m sup 2 to 7.15x7.15 mm sup 2 with magnifications from 4x to 40x. With the highest magnification 480 lp/mm had been achieved at 10% modulation transfer function which corresponds to a spatial resolution of 1.04 mu m. A low-noise fast-readout CCD camera transfers 2048x2048 pixels within 100-250 ms at a dynamic range of 12-14 bit to the file server. A user-friendly graphical interface gives access to the main parameters needed for ...

  4. Energy dispersive X-ray fluorescence from useless tyres samples with a Si PIN detector

    International Nuclear Information System (INIS)

    The concentration of Zn from discard tyre samples is of environmental interest, since on its production are used S for the rubber vulcanization process, and Zn O as reaction catalyze. The useless tyres are been used for asphalt pave, burn in cement industry and thermoelectric power plant and in erosion control of agriculture areas. Analyses of these samples requires frequently chemical digestion that is expensive and take a long time. Trying to eliminate these limitations, the objective of this work was use Energy Dispersive X Ray Fluorescence technique (EDXRF) with a portable system as the technique is multi elementary and needs a minimum sample preparation. Five useless tyres samples were grind in a knife mill and after this in a cryogenic mill, and analyzed in pellets form, using a X ray mini tube (Ag target, Mo lter, 25 kV/20 A) for 200 s and a Si-PIN semiconductor detector coupled to a multichannel analyzer. Were obtained Zn concentrations in the range of 40.6 to 44.2 g g1, representing nearly 0.4. (author)

  5. Development of Position-sensitive Transition-edge Sensor X-ray Detectors

    Science.gov (United States)

    Smith, S. J.; Bandler, S. R.; Brekosky, R. P.; Brown, A.-D.; Chervenak, J. A.; Eckard, M. E.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. s.; Sad (eor. K/ E/); Figueroa-Feliciano, E.

    2008-01-01

    We report on the development of position-sensitive transition-edge sensors (PoST's) for future x-ray astronomy missions such as the International X-ray Observatory (IXO), currently under study by NASA and ESA. PoST's consist of multiple absorbers each with a different thermal coupling to one or more transition-edge sensor (TES). This differential thermal coupling between absorbers and TES's results in different characteristic pulse shapes and allows position discrimination between the different pixels. The development of PoST's is motivated by a desire to achieve maximum focal-plane area with the least number of readout channels and as such. PoST's are ideally suited to provide a focal-plane extension to the Constellation-X microcalorimeter array. We report the first experimental results of our latest one and two channel PoST's, which utilize fast thermalizing electroplated Au/Bi absorbers coupled to low noise Mo/Au TES's - a technology already successfully implemented in our arrays of single pixel TES's. We demonstrate 6 eV energy resolution coupled with spatial sensitivity in the keV energy range. We also report on the development of signal processing algorithms to optimize energy and position sensitivity of our detectors.

  6. Application of the alanine detector to gamma-ray, X-ray and fast neutron dosimetry

    International Nuclear Information System (INIS)

    A dosimeter based on alanine has been developed at the INP in Krakow and at Risoe National Laboratory. Due to its near tissue-equivalence and stability of signal, measured using ESR spectrometry at room temperature, this free-radical amino-acid dosimetric system is particularly suitable for measuring X-ray, gamma-ray and fast neutron doses in the range 10-105 Gy. The relative effectiveness (with respect to 60Co γ-rays) of the alanine dosimeter to 250 kVp X-rays and to cyclotron-produced fast neutrons (mean neutron energy 5.6 MeV) is measured to be 0.76± 0.06 and 0.60±0.05, respectively. The suitability of the alanine dosimeter for intercomparison gamma-ray dosimetry is also shown. The estimated absolute difference between 60Co dosimetry at Risoe National Laboratory and at the Centre of Oncology in Krakow is about 5%, somewhat more than the experimental uncertainty. These results are based on ESR measurements performed in Krakow on about 25% of the exposed detectors. 28 refs., 2 figs., 3 tabs. (author)

  7. Applications of CdTe detectors in x-ray imaging and metrology

    International Nuclear Information System (INIS)

    Operating as a photoconductor, the sensitivity and the impulse response of semi-insulating materials greatly depend on the excitation duration compared to electron and hole lifetimes. The characteristic of ohmic contact for these compounds is shortly discussed. Before developing picosecond measurements with integrated autocorrelation system, this paper explains high energy industrial tomographic application with large CdTe detectors (25x15x0.9 mm3) where spatial resolution, contrast and wide dynamic are the main criteria. The excitation is typically micros range. X-ray flash radiography with 10 ns burst, is in an intermediate time domain where excitation is similar to electron life-time in cadmium telluride. In laser fusion experiment the excitation is in the range of 50 ps and the authors develop for such high band devices photoconductive structures able to study very short x-ray emission. Thin polycrystalline MOCVD CdTe films with picosecond response is an alternative material suitable to perform optical correlation measurements of single shot pulses with a very large bandwidth (∼50 GHz)

  8. The speedster-EXD - A new event-triggered hybrid CMOS x-ray detector

    CERN Document Server

    Griffith, Christopher V; Prieskorn, Zachary R; Burrows, David N

    2014-01-01

    We present preliminary characterization of the Speedster-EXD, a new event driven hybrid CMOS detector (HCD) developed in collaboration with Penn State University and Teledyne Imaging Systems. HCDs have advantages over CCDs including lower susceptibility to radiation damage, lower power consumption, and faster read-out time to avoid pile-up. They are deeply depleted and able to detect x-rays down to approximately 0.1 keV. The Speedster-EXD has additional in-pixel features compared to previously published HCDs including: (1) an in-pixel comparator that enables read out of only the pixels with signal from an x-ray event, (2) four different gain modes to optimize either full well capacity or energy resolution, (3) in-pixel CDS subtraction to reduce read noise, and (4) a low-noise, high-gain CTIA amplifier to eliminate interpixel capacitance crosstalk. When using the comparator feature, the user can set a comparator threshold and only pixels above the threshold will be read out. This feature can be run in two mode...

  9. Comparison of beam quality parameters computed from mammographic x-ray spectra measured with different high-resolution semiconductor detectors

    International Nuclear Information System (INIS)

    In this work, the x-ray spectra of standard mammographic radiation qualities were measured with Si(Li), SDD and CdTe detectors. The x-ray source was an industrial x-ray tube with an Mo anode, operating at constant tube potentials between 20 and 35 kV, and adapted with filters of Mo and Al, in order to reproduce standard mammographic beam qualities. The measured spectra were corrected by the energy response of each detector, which were determined using Monte Carlo simulation. From the corrected spectra, values of HVL and mean energies were computed. The results show that, after correction by the energy response functions, all detectors provided similar bremsstrahlung spectra, whereas greater differences were observed in the characteristic peaks, due to the different energy resolutions of the detection systems. The comparison between values of HVL and mean energies calculated from the spectra obtained with each detector also show good agreement, with differences up to 5.5%. For most of the conditions studied, the differences between the measured values of HVL and those computed from the corrected spectra are lesser than the experimental uncertainties. Finally, our results show that, although the detectors Si(Li), SDD and CdTe provide similar spectra, the use of the first two detectors, which combine high energy resolution and low spectral distortions, is recommended, since they provide more accurate spectra from which several quality parameters can be determined. - Highlights: ► The Si(Li), SDD and CdTe detectors were applied for mammographic x-ray spectroscopy. ► The x-ray spectra measured with these detectors are similar, showing differences only in the characteristic peaks. ► The mean energies and values of HVL computed from the measured spectra with these detectors also show small differences. ► The use of Si(Li) detectors and SDD is advantageous due to their better energy resolution

  10. Development of an X-ray HARP–FEA detector system for high-throughput protein crystallography

    International Nuclear Information System (INIS)

    A new detector system for protein crystallography based on an X-ray HARP–FEA is presented. A new detector system for protein crystallography is now being developed based on an X-ray HARP–FEA (high-gain avalanche rushing amorphous photoconductor–field emitter array), which consists of an amorphous selenium membrane and a matrix field emitter array. The combination of the membrane avalanche effect with a single driven FEA has several advantages over currently available area detectors, including higher sensitivity, higher spatial resolution and a higher frame rate. Preliminary evaluation of the detector has been carried out and its effectiveness has been confirmed. Next, diffraction images were measured with continuous rotation of a protein crystal, and the images were compared with those measured by the existing CCD detector; the system successfully obtained high-spatial-resolution images. Using shutterless measurement, the total measurement time can be reduced significantly, making the method appropriate for high-throughput protein crystallography. The X-ray HARP–FEA detector is an attractive candidate for the next generation of X-ray area detectors

  11. Optimum spectroscopic performance from CZT γ- and X-ray detectors with pad and strip segmentation

    International Nuclear Information System (INIS)

    We describe a method for obtaining optimum spectroscopic performance from CZT γ- and X-ray detectors with segmented readout. This method allows to circumvent the effects of incomplete charge collection and to obtain energy resolution approaching the limitation due to detector and electronic noise. It is insensitive to hole trapping over most of the detector volume, while a modest amount of electron trapping can be tolerated. The method requires segmentation of the positive electrode. Signals from the common electrode, taken in coincidence with those of the segmented positive electrode, provide a measure of the depth of interaction. A distinct correlation profile exists between the signals of the segmented element and the common electrode. These profiles can be linearized to yield very sharp energy lines with high photopeak efficiency. Additional cuts can be made to improve peak-to-valley ratio, with small loss in efficiency. We present measurements taken with CZT detectors with pad segmentation. Illuminating with a 133Ba source, we obtain for the 356 keV line a FWHM of 1.0-1.5%, with a peak-to-valley ratio of ∼100/1

  12. Neutron Induced Backgrounds In the MIXE X-Ray Detector at Balloon Altitudes

    Science.gov (United States)

    Armstrong, T. W.; Colborn, B. L.; Dietz, K. L.; Ramsey, B. D.

    1997-01-01

    The MIXE detector developed at NASA/MSFC is designed for x-ray astronomy and consists of a multiwire proportional counter sensitive to photons less than 150 keV. The detector has been flown on several balloon flights with higher than expected background levels observed. Previous predictions of the detector background due to atmospheric gamma-ray and cosmic diffuse sources were much less (factor of 3) than flight background measurements. The work reported here was undertaken to determine if the additional contribution from gamma-rays generated by albedo and cosmic-ray induced neutrons in the detector and payload assembly could account for the background levels observed. Monte Carlo nuclear interaction and radiation transport simulations were made for the ambient cosmic-ray environment corresponding to a previous MEE balloon flight at 3 g/cm(exp 2) residual atmosphere and 42 N geomagnetic latitude. The omnidirectional albedo neutron spectrum and the GCR proton spectrum which were used as input to the calculations are shown. For the albedo angular distribution, the predicted up/down flux ratio of 2.5 was used together with the angular dependence measured by Preszler, et al.

  13. Mapping the large area straw detectors of the COMPASS experiment with X-rays

    CERN Document Server

    Platzer, Klaus; Dünnweber, Wolfgang; Faessler, Martin A; Geyer, Reiner; Ilgner, C; Peshekhonov, Vladimir D; Wellenstein, Hermann

    2005-01-01

    In the COMPASS experiment at CERN, large straw drift tube detectors are used for large-angle tracking. To minimize the total areal density, a self supporting structure of thin-walled plastic tubes was chosen and, hence, a loss in mechanical precision was accepted. A complete mapping of the anode wire coordinate grid was required. An X-ray apparatus using a charge-coupled device (CCD) as imaging detector was built to investigate the mechanical properties and to calibrate (offline) the wire positions. Deviations of typically 200-400 mu m from the nominal positions, defined by equal spacing, are found across the detector area of 8 m/sup 2/. With a calibration method based on high-resolution CCD imaging and pattern recognition algorithms, the absolute wire coordinates are determined with an accuracy better than 30 mu m across the whole detector area. Temperature effects are clearly seen. Their inhomogenity limits the achievable accuracy to about 50 mu m under realistic experimental conditions, which is sufficient...

  14. Optimized readout methods of silicon drift detectors for high-resolution X-ray spectroscopy

    International Nuclear Information System (INIS)

    Silicon Drift Detectors with integrated FET transistor fabricated at Max-Planck-Institute in Munich in cooperation with PNSensor GmbH are widely used as X-ray sensors in many industrial and scientific applications. In the classical readout scheme, the integrated transistor on the SDD is operated in the source-follower configuration. The signal charge is removed continuously by the detector self-rest mechanism. The method gives very good results at counting rates up to 10 kcps. For higher count rates, the FWHM increases with the growing reset current and a slight shift of the energy peak is observed. The relative large signal rise time can be also a limitation for operation at very high count rates. Alternatively, the SDD can be operated in a Charge Sensitive Amplifier (CSA) configuration. The detector signal charge is integrated on a feedback capacitor across an inverting amplifier with the integrated FET as the input transistor. The signal rise time does not depend on the integrated transistor and can be made very short (e.g. 50 ns). In applications requiring very high counting rates and constant energy resolution, pulsed-reset operation of the SDD is desirable. The signal charge is removed by applying short reset pulses to a reset structure integrated on the detector anode. The combination of the CSA readout scheme and the pulsed-reset method allows the operation at the best energy resolution independent on the count rate

  15. The ''RAPID'' high rate large area X-ray detector system

    International Nuclear Information System (INIS)

    The multiwire proportional counter (MWPC) is a well-established device for capturing X-ray images from synchrotron sources and is particularly well suited to dynamic experiments. Its advantages include, almost zero noise, high dynamic range limited only by the electronic memory depth, large area and time resolutions of microseconds. It does however have some limitations, notably in global and local count rate performance. The RAPID two-dimensional detector system delivers a more than twentyfold increase in throughput over present systems. It comprises a ''wire microgap'' detector, which has much higher count rate performance than coventional MWPCs and a sophisticated multi-channel data acquisition system. The system has a global count rate capability of greater than 2 x 107 photons s-1 with a maximum local count rate of ∝106 photons mm-2 s-1. A spatial resolution of ∝200 μm, over an active area of 12.8 x 12.8 cm, has been achieved which compares well with exiting read-out systems. Each electrode of the detector is instrumented with a preamplifier and ADC and the position of the event is determined independently in X and Y by centroiding the induced charge distribution. The X and Y coordinates are correlated using a unique time stamp. This paper described the design and performance of the detector and read-out system and presents some recent beamline results. (orig.)

  16. Characterization of Si hybrid CMOS detectors for use in the soft X-ray band

    Energy Technology Data Exchange (ETDEWEB)

    Prieskorn, Zachary, E-mail: zpriesko@gmail.com; Griffith, Christopher V.; Bongiorno, Stephen D.; Falcone, Abraham D.; Burrows, David N.

    2013-07-21

    We report on the characterization of four Teledyne Imaging Systems HAWAII Hybrid Si CMOS detectors designed for X-ray detection. Three H1RG detectors were studied along with a specially configured H2RG. Read noise measurements were performed, with the lowest result being 7.1 e{sup −} RMS. Interpixel capacitive crosstalk (IPC) was measured for the three H1RGs and for the H2RG. The H1RGs had IPC upper limits of 4.0–5.5% (up and down pixels) and 8.7–9.7% (left and right pixels), indicating a clear asymmetry. Energy resolution is reported for two X-ray lines, 1.5 and 5.9 keV, at multiple temperatures between 150 and 210 K. The best resolution measured at 5.9 keV was 250 eV (4.2%) at 150 K, with IPC contributing significantly to this measured energy distribution. The H2RG, with a unique configuration designed to decrease the capacitive coupling between ROIC pixels, had an IPC of 1.8±1.0% indicating a dramatic improvement in IPC with no measurable asymmetry. We also measured dark current as a function of temperature for each detector. For the detector with the lowest dark current, at 150 K, we measured a dark current of 0.020±0.001 (e{sup −} s{sup −1} pixel{sup −1}). There is also a consistent break in the fit to the dark current data for each detector. Above 180 K, all the data can be fit by the product of a power law in temperature and an exponential. Below 180 K the dark current decreases more slowly; a shallow power law or constant must be added to each fit, indicating a different form of dark current is dominant in this temperature regime. Dark current figures of merit at 293 K are estimated from the fit for each detector.

  17. High-Resolution Detector for At-Wavelength Metrology of X-Ray Optics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Since the launch of the first X-ray focusing telescope in 1963, the development of grazing incidence X-ray optics has been crucial to the development of the field...

  18. Real time 2 dimensional detector for charged particle and soft X-ray images

    International Nuclear Information System (INIS)

    The conventional instruments used in experiments for the soft X-ray region such as X-ray diffraction analysis are X-ray films or imaging plates. However, these instruments are not suitable for real time observation. In this paper, newly developed imaging devices will be presented, which have the capability to take X-ray images in real time with a high detection efficiency. Also, another capability, to take elementary particle tracking images, is described. (orig.)

  19. Substrate and Passivation Techniques for Flexible Amorphous Silicon-Based X-ray Detectors

    Directory of Open Access Journals (Sweden)

    Michael A. Marrs

    2016-07-01

    Full Text Available Flexible active matrix display technology has been adapted to create new flexible photo-sensing electronic devices, including flexible X-ray detectors. Monolithic integration of amorphous silicon (a-Si PIN photodiodes on a flexible substrate poses significant challenges associated with the intrinsic film stress of amorphous silicon. This paper examines how altering device structuring and diode passivation layers can greatly improve the electrical performance and the mechanical reliability of the device, thereby eliminating one of the major weaknesses of a-Si PIN diodes in comparison to alternative photodetector technology, such as organic bulk heterojunction photodiodes and amorphous selenium. A dark current of 0.5 pA/mm2 and photodiode quantum efficiency of 74% are possible with a pixelated diode structure with a silicon nitride/SU-8 bilayer passivation structure on a 20 µm-thick polyimide substrate.

  20. Radiation effects on the proportional counter X-ray detectors on board the NEAR spacecraft

    International Nuclear Information System (INIS)

    The X-ray proportional counters on board the Near Earth Asteroid Rendezvous (NEAR) spacecraft have exhibited a resolution degradation and recovery phenomenon several times during the long cruise phase of the mission. The resolution is checked periodically by commanding an 55Fe source into the window area. The degradation is seen as a low energy tailing of the 5.9 keV photopeak. Two events have occurred which provided good spectral data for better understanding the degradation phenomenon. In November 1997 a large solar particle event occurred that degraded the resolution and excited copper in the collimator. Eventually the detectors returned to normal. In January 1998 the spacecraft performed an Earth swingby gravity assist maneuver. The near Earth environment excited the magnesium and aluminum in the filter elements. The copper line was also produced. The NEAR spacecraft was launched in February 1996 and will rendezvous and orbit the asteroid 433 Eros in early 1999

  1. Substrate and Passivation Techniques for Flexible Amorphous Silicon-Based X-ray Detectors.

    Science.gov (United States)

    Marrs, Michael A; Raupp, Gregory B

    2016-01-01

    Flexible active matrix display technology has been adapted to create new flexible photo-sensing electronic devices, including flexible X-ray detectors. Monolithic integration of amorphous silicon (a-Si) PIN photodiodes on a flexible substrate poses significant challenges associated with the intrinsic film stress of amorphous silicon. This paper examines how altering device structuring and diode passivation layers can greatly improve the electrical performance and the mechanical reliability of the device, thereby eliminating one of the major weaknesses of a-Si PIN diodes in comparison to alternative photodetector technology, such as organic bulk heterojunction photodiodes and amorphous selenium. A dark current of 0.5 pA/mm² and photodiode quantum efficiency of 74% are possible with a pixelated diode structure with a silicon nitride/SU-8 bilayer passivation structure on a 20 µm-thick polyimide substrate. PMID:27472329

  2. Active Detectors for Plasma Soft X-Ray Detection at PALS

    Directory of Open Access Journals (Sweden)

    C. Granja

    2010-01-01

    Full Text Available This paper summarizes the work carried out for an experimental study of low-energy nuclear excitation by laser-produced plasma at the PALS Prague laser facility. We describe the adaptation and shielding of single-quantum active radiation detectors developed at IEAP CTU Prague to facilitate their operation inside the laser interaction chamber in the vicinity of the plasma target. The goal of this effort is direct real-time single-quantum detection of plasma soft X-ray radiation with energy above a few keV and subsequent identification of the decay of the excited nuclear states via low-energy gamma rays in a highly radiative environment with strong electromagnetic interference.

  3. X-ray-sensitive hybrid photon detectors with Be-windows

    CERN Document Server

    D'Ambrosio, Carmelo; Leutz, Heinrich; Puertolas, D; Rosso, Ettore

    2005-01-01

    A 0.3-mm thin YAlO/sub 3/(Ce) scintillating crystal plate of 22 mm diameter was mounted inside an electrostatic-focussed hybrid photomultiplier tube (HPMT). The photocathode was evaporated directly on this scintillating plate opposite to the HPMT-anode. The HPMT was vacuum-sealed with a 1-mm thick Be radiation entrance window. Photoelectron numbers at their peak energies of photoabsorption and energy resolutions were measured between 3.69 and 59.6 keV. The average number of photoelectrons produced per keV radiation energy was determined to be 4.457 phel/keV and the energy resolution at 59.6 keV was 17%. Introducing in the same way such a thin YAlO/sub 3/(Ce) plate inside an imaging silicon pixel array (ISPA) tube would improve its spatial resolution, since it depends on the thickness of the X- ray detector.

  4. Quantification of thin film crystallographic orientation using X-ray diffraction with an area detector

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Jessica L; Jimison, Leslie H; Mannsfeld, Stefan; Volkman, Steven; Yin, Shong; Subramanian, Vivek; Salleo, Alberto; Alivisatos, A Paul; Toney, Michael F

    2010-02-19

    As thin films become increasingly popular (for solar cells, LEDs, microelectronics, batteries), quantitative morphological information is needed to predict and optimize the film's electronic, optical and mechanical properties. This quantification can be obtained quickly and easily with X-ray diffraction using an area detector and synchrotron radiation in two simple geometries. In this paper, we describe a methodology for constructing complete pole figures for thin films with fiber texture (isotropic in-plane orientation). We demonstrate this technique on semicrystalline polymer films, self-assembled nanoparticle semiconductor films, and randomly-packed metallic nanoparticle films. This method can be immediately implemented to help understand the relationship between film processing and microstructure, enabling the development of better and less expensive electronic and optoelectronic devices.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sievers, Peter

    2012-12-07

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Talla, Patrick Takoukam

    2011-04-07

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

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

    International Nuclear Information System (INIS)

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

  9. Evaluation of image quality and appropriate X-ray exposure of a flat panel detector

    International Nuclear Information System (INIS)

    We evaluated image quality and necessary patient exposure when using the CXDI-11 (Canon Inc.) flat panel detector (FPD). This detector, which consists of a rare earth fluorescent screen (Gd2O2S: Tb) and amorphous silicon sensor, was compared with the FCR-5000 (Fuji Film Medical Co., Ltd.) CR and the UR-3/HGM2 (Fuji Film Medical Co., Ltd.) film-screen (F/S) combination. Comparisons of both physical imaging characteristics and clinical image quality were carried out. The final MTF of the FPD was found to be similar to or better than those of the CR and F/S systems. For identical exposures, the overall Wiener spectrum of the FPD was found to be slightly poorer than that of the F/S combination. The NEQ of the FPD was found to be similar to or better than those of the CR and F/S systems. Comparison of chest images showed that the FPD produced images with quality comparable to or higher than those of the CR system. Similarly, evaluation of abdominal and bone images using a 5-scale method showed that the FPD produced images with quality comparable to or higher than those of the CR system. As with CR, the x-ray quantum mottle in FPD images becomes noticeable at low exposures. Clinical images were therefore taken with a 30% increase in exposure, giving a Wiener spectrum for the FPD images similar to that obtained with the F/S images. This is probably not a significant increase in exposure, given the improvement in image quality and increased ease of use provided by the CXDI system. Further, future improvements in hardware and image processing may allow images to be taken with the same exposure used for F/S images. Our evaluation of both image quality and x-ray exposure has therefore indicated the value of the FPD in the clinical environment. (author)

  10. Signal formation and decay in CdTe x-ray detectors under intense irradiation.

    Science.gov (United States)

    Jahnke, A; Matz, R

    1999-01-01

    The response of Cd(Zn)Te Schottky and resistive detectors to intense x-rays is investigated in a commercial computed tomography (CT) system to assess their potential for medical diagnostics. To describe their signal height, responsivity, signal-to-noise ratio (SNR), and detective quantum efficiency the devices are modeled as solid-state ionization chambers with spatially varying electric field and charge collection efficiency. The thicknesses and pixel areas of the discrete detector elements are 0.5-2 mm and a few mm2, respectively. The incident spectrum extends from 26 to 120 keV and comprises 10(10) quanta/s cm2. It photogenerates a carrier concentration in the semiconductor that is two to three orders of magnitude above the intrinsic concentration, but remains to a similar extent below the charge densities on the device electrodes. Stable linear operation is achieved with the Schottky-type devices under high bias. Their behavior can be modeled well if negatively charged near-midgap bulk defects with a concentration of 10(11)-10(13) cm-3 are assumed. The bulk defects explain the amount and time constant (about 100 ms) of the detrapping current measured after x-ray pulses (afterglow). To avoid screening by the trapped space charge the bias voltage should exceed 100(V) x [detector thickness/mm]2. Dark currents are of the order of the generation-recombination current, i.e., 300 pA/mm3 detector volume. With proper device design the signal height approaches the theoretical maximum of 0.2 A/W. This high responsivity, however, is not exploited in CT since the SNR is determined here by the incident quantum noise. As a consequence of the detrapping current, the response speed does not meet CT requirements. A medium-term effort for crystal growth appears necessary to achieve the required reduction of the trap density by an order of magnitude. Scintillation based detectors are, therefore, still preferred in fast operating medical diagnostic systems. PMID:9949396

  11. Clinical diagnostic Compton scattering x-ray spectrometry using simulated HPGe detector responses

    International Nuclear Information System (INIS)

    The superior energy resolution of high-purity germanium (HPGe) detectors offers an advantage for accurate x-ray spectrometry. However, the photon fluence rates of clinical tubes are usually much higher than the count rates that can be handled by the detector without a pulse pile -up. The use of a Compton scattering method is very efficient in reducing the fluence rate. A Compton scattering spectrometer, the Spectro-X (RTI Electronics, Sweden), is now commercially available. The x-ray beam is scattered by a lucite rod (D 4mm) placed in the spectrometer and the beam is collimated to ensure that only the photons scattered at 90 degrees enter an HPGe detector (EG and G Ortec planar model GLP-10180/07, Oak Ridge, TN, USA). The primary spectrum is then reconstructed, using an algorithm, from the measured detector pulse-height distribution (PHD). A method to improve the reconstruction algorithm of this spectrometer system was developed. It consists of calculating the response functions of the detector placed in the spectrometer system using Monte Carlo simulations. The response functions were computed for a set of 1450 narrow energy windows (0.1 keV, uniformly distributed) primary beams covering the useful range for diagnostic radiology (from 5 keV up to 150 keV), using the EGSnrc code system. The primary beams simulated were parallel photon beams covering a rectangular field of 4 mm x 40 mm originating 1 metre from the axis of the lucite rod and going towards it. To reduce simulation times, only the photon transport was simulated and energies transferred to electrons were deposited locally. The simulations were run on personal computers (PC) running Linux, either a PC having a 1.4 GHz AMD Athlon processor, or one of three IBM eServers xSeries 330 having dual 1.266 GHz Intel Pentium III processors. 1010 photons were simulated for each of the 1450 energy windows and it took on average 12.5 hours of CPU time per energy window. Each response function was stored in an array

  12. X-ray tests of a microchannel plate detector and amorphous silicon pixel array readout for neutron radiography

    International Nuclear Information System (INIS)

    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

  13. The hard X-ray response of epitaxial GaAs detectors

    CERN Document Server

    Owens, A; Kraft, S; Peacock, A; Nenonen, S; Andersson, H

    2000-01-01

    We report on hard X-ray measurements with two epitaxial GaAs detectors of active areas 2.22 mm sup 2 and thicknesses 40 and 400 mu m at the ESRF and HASYLAB synchrotron research facilities. The detectors were fabricated using high-purity material and in spite of an order of magnitude difference in depletion depths, they were found to have comparable performances with energy resolutions at -45 deg. C of approx 1 keV fwhm at 7 keV rising to approx 2 keV fwhm at 200 keV and noise floors in the range 1-1.5 keV. At energies <30 keV, the energy resolution was dominated by leakage current and electromagnetic pick-up, while at the highest energies measured, the resolutions approach the expected Fano limit (e.g., approx 1 keV near 200 keV). Both detectors are remarkably linear, with average rms non-linearities of 0.2% over the energy range 10-60 keV, which, taken in conjunction with Monte-Carlo results indicate that charge collection efficiencies must be in excess of 98%. This is consistent with material science me...

  14. Superconducting tunneling junctions as X-ray detectors and their possible applications in astrophysics

    Science.gov (United States)

    Twerenbold, Damian

    1988-12-01

    Superconducting tunneling junctions (STJ) have been demonstrated to be sensitive detectors for X-rays at energies of 6 keV. The measured energy resolution for Sn/Sn-oxide/Sn junctions (75 × 75 μm2) at an operating temperature below 0.5 K is 65 eV (FWHM) at an energy of 5.89 keV. An extrapolation to vanishing electronic noise yielded a resolution of 40 eV. This improved energy resolution compared to conventional semiconductors is due to the thousand times smaller energy gap of a superconductor. The mechanisms of the detector is the production of excess quasiparticles (single particle electronic excitations) by the breaking of Cooper pairs (condensed electronic ground state). These excess quasiparticles tunnel across the insulating barrier owing to the quantum mechanical tunneling effect. The additional current is integrated by means of a charge sensitive preamplifier. The basic physics of the detector is presented and possible applications in astrophysics are discussed. Present address: Institut de Physique, Rue A.-L. Breguet 1, CH-2000 Neuchâtel, Switzerland.

  15. Detector for imaging of explosions: present status and future prospects with higher energy x-rays

    Science.gov (United States)

    Aulchenko, V. M.; Evdokov, O. V.; Shekhtman, L. I.; Ten, K. A.; Tolochko, B. P.; Zhogin, I. L.; Zhulanov, V. V.

    2008-05-01

    The described detector for imaging of explosions (DIMEX) has been in operation on the synchrotron radiation (SR) beam-line on the VEPP-3 electron ring at Budker INP since 2002. DIMEX is based on a one-coordinate gas ionization chamber filled with a Xe-CO2(3:1) mixture at 7atm and active Frisch-grid made of a Gas Electron Multiplier (GEM). The detector has a spatial resolution of 0.2mm and dynamic range of ~100, which allows one to achieve a signal measurement precision of a few percent. The frame rate can be tuned up to 8 MHz (125 ns per image) and as many as 32 images can be stored in one shot. At present DIMEX is used with the X-ray beam from a 2T wiggler with an average energy of 20 keV. The future possibility to install a similar detector on the SR beam-line on the VEPP-4 electron ring is discussed.

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

    CERN Document Server

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

    2001-01-01

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

  17. Comparison of X-ray detectors for a diffraction enhanced imaging system

    CERN Document Server

    Kiss, M Z; Zhong Zhon

    2002-01-01

    Three digital detector systems--a Fuji BAS2500 Image Plate Reader, a prototype charge-coupled device (CCD) from Mar USA and the MicroPhotonics XQUIS 1000 were compared with respect to format, dynamic range, dark noise, and spatial resolution. Experiments were conducted using highly collimated monochromatic X-rays at 20 keV, produced at the National Synchrotron Light Source. This study characterized digital detectors being considered for integration into a synchrotron-based diffraction enhanced imaging (DEI) apparatus used for medical imaging research, particularly mammography. These detectors are also being considered for integration into a proposed clinical prototype for DEI-based mammography. While all three systems had comparable image quality, the CCDs had faster readout time than the image plate system. However, the Fuji system had the largest dynamic range (approx 10 sup 5 compared to 10 sup 4 for CCDs) and the largest active area. The MicroPhotonics XQUIS 1000 had the best spatial resolution as charact...

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

    Science.gov (United States)

    Watt, J.; Bates, R.; Campbell, M.; Mathieson, K.; Mikulec, B.; O'Shea, V.; Passmore, M.-S.; Schwarz, C.; Smith, K. M.; Whitehill, C.; XIMAGE Project

    2001-03-01

    Hybrid semiconductor pixel detectors are being investigated as imaging devices for radiography and synchrotron radiation beam applications. Based on previous work in the CERN RD19 and the UK IMPACT collaborations, a photon counting GaAs pixel detector (PCD) has been used in an X-ray powder diffraction experiment. The device consists of a 200 μm thick SI-LEC GaAs detector patterned in a 64×64 array of 170 μm pitch square pixels, bump-bonded to readout electronics operating in single photon counting mode. Intensity peaks in the powder diffraction pattern of KNbO 3 have been resolved and compared with results using the standard scintillator, and a PCD predecessor (the Ω3). The PCD shows improved speed, dynamic range, 2-D information and comparable spatial resolution to the standard scintillator based systems. It also overcomes the severe dead time limitations of the Ω3 by using a shutter based acquisition mode. A brief demonstration of the possibilities of the system for dental radiography and image processing are given, showing a marked reduction in patient dose and dead time compared with film.

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

    Science.gov (United States)

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

    2016-01-01

    The Speedster-EXD is a new 64×64 pixel, 40-μm pixel pitch, 100-μm depletion depth hybrid CMOS x-ray detector with the capability of reading out only those pixels containing event charge, thus enabling fast effective frame rates. A global charge threshold can be specified, and pixels containing charge above this threshold are flagged and read out. The Speedster detector has also been designed with other advanced in-pixel features to improve performance, including a low-noise, high-gain capacitive transimpedance amplifier that eliminates interpixel capacitance crosstalk (IPC), and in-pixel correlated double sampling subtraction to reduce reset noise. We measure the best energy resolution on the Speedster-EXD detector to be 206 eV (3.5%) at 5.89 keV and 172 eV (10.0%) at 1.49 keV. The average IPC to the four adjacent pixels is measured to be 0.25%±0.2% (i.e., consistent with zero). The pixel-to-pixel gain variation is measured to be 0.80%±0.03%, and a Monte Carlo simulation is applied to better characterize the contributions to the energy resolution.

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

    CERN Document Server

    Griffith, Christopher V; Prieskorn, Zachary R; Burrows, David N

    2016-01-01

    The Speedster-EXD is a new 64x64 pixel, 40 $\\mu$m pixel pitch, 100 $\\mu$m depletion depth hybrid CMOS X-ray detector (HCD) with the capability of reading out only those pixels containing event charge, thus enabling fast effective frame rates. A global charge threshold can be specified, and pixels containing charge above this threshold are flagged and read out. The Speedster detector has also been designed with other advanced in-pixel features to improve performance, including a low-noise, high-gain CTIA amplifier that eliminates interpixel capacitance crosstalk (IPC), and in-pixel Correlated Double Sampling (CDS) subtraction to reduce reset noise. We measure the best energy resolution on the Speedster-EXD detector to be 206 eV (3.5 %) at 5.89 keV and 172 eV (10.0 %) at 1.49 keV. The average IPC to the four adjacent pixels is measured to be 0.25 $\\pm$ 0.2 % (i.e. consistent with zero). The pixel-to-pixel gain variation is measured to be 0.80 $\\pm$ 0.03 %, and a Monte Carlo simulation is applied to better chara...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-03-11

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

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

    Science.gov (United States)

    Warburton, W. K.; Harris, J. T.; Friedrich, S.

    2015-06-01

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

  3. PILATUS: A single photon counting pixel detector for X-ray applications

    International Nuclear Information System (INIS)

    The hybrid pixel technology combines silicon sensors with CMOS-processing chips by a 2D micro bump-bonding interconnection technology developed at Paul Scherrer Institute [C. Broennimann, E.F. Eikenberry, B. Henrich, R. Horisberger, G. Huelsen, E. Pohl, B. Schmitt, C. Schulze-Briese, M. Suzuki, T. Tomizaki, H. Toyokawa, A. Wagner. J. Synchrotron Rad. 13 (2005) 120 ; T. Rohe, C. Broennimann, F. Glaus, J. Gobrecht, S. Heising, M. Horisberger, R. Horisberger, H.C. Kaestl, J. Lehmann, S. Streuli, Nucl. Instr. and Meth. Phys. Res. A 565 (2006) 303 ]. PILATUS hybrid pixel detectors like other instruments [X. Llopart, M. Campell, R. Dinapoli, D. San Segundo, E. Pernigotti. IEEE Trans. Nucl. Sci. 49 (2002) 2279 ; N. Boudet, J.-F. Berar, L. Blanquart, P. Breugon, B. Caillot, J.-C. Clemens, I. Koudobine, P. Delpierre, C. Mouget, R. Potheau, I. Valin, Nucl. Instr. and Meth. Phys. Res. A 510 (2003) 41 ] are operating in the so-called 'single photon counting mode': Every X-ray quantum is directly converted into an electrical signal and counted by the detector system. Several prototype detectors in various geometries were produced, tested and established at different synchrotron beamlines worldwide. We explain the technology and present some recent highlights from various fields of applications.

  4. X-ray and gamma-ray standards for detector calibration

    International Nuclear Information System (INIS)

    The IAEA established a Co-ordinated Research Programme (CRP) on the Measurements and Evaluation of X- and Gamma-Ray Standards for Detector Efficiency Calibration in 1986 with the aim of alleviating the generation of such discrepancies. Within the framework of this CRP, representatives of nine research groups from six Member States and one international organization performed a number of precise measurements and systematic in-depth evaluations of the required decay data. They have also contributed to the development of evaluation methodology and measurement techniques, and stimulated a number of such studies at laboratories not directly involved in the IAEA project. The results of the work of the CRP, which was finished in 1990, are presented in this report. Recommended values of half-lives and photon emission probabilities are given for a carefully selected set of radionuclides that are suitable for detector efficiency calibration (X-rays from 5 to 90 keV and gamma-rays from 30 to about 3000 keV). Detector efficiency calibration for higher gamma-ray energies (up to 14 MeV) is also considered. The evaluation procedures used to obtain the recommended values and their estimated uncertainties are reported, and a summary of the remaining discrepancies is given. Refs and tabs

  5. PILATUS: A single photon counting pixel detector for X-ray applications

    Energy Technology Data Exchange (ETDEWEB)

    Henrich, B. [Paul Scherrer Institute, 5232 Villigen PSI (Switzerland)], E-mail: beat.henrich@psi.ch; Bergamaschi, A. [Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Broennimann, C. [DECTRIS AG, 5232 Villigen PSI (Switzerland); Dinapoli, R. [Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Eikenberry, E.F. [DECTRIS AG, 5232 Villigen PSI (Switzerland); Johnson, I. [Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Kobas, M. [DECTRIS AG, 5232 Villigen PSI (Switzerland); Kraft, P.; Mozzanica, A.; Schmitt, B. [Paul Scherrer Institute, 5232 Villigen PSI (Switzerland)

    2009-08-01

    The hybrid pixel technology combines silicon sensors with CMOS-processing chips by a 2D micro bump-bonding interconnection technology developed at Paul Scherrer Institute [C. Broennimann, E.F. Eikenberry, B. Henrich, R. Horisberger, G. Huelsen, E. Pohl, B. Schmitt, C. Schulze-Briese, M. Suzuki, T. Tomizaki, H. Toyokawa, A. Wagner. J. Synchrotron Rad. 13 (2005) 120 ; T. Rohe, C. Broennimann, F. Glaus, J. Gobrecht, S. Heising, M. Horisberger, R. Horisberger, H.C. Kaestl, J. Lehmann, S. Streuli, Nucl. Instr. and Meth. Phys. Res. A 565 (2006) 303 ]. PILATUS hybrid pixel detectors like other instruments [X. Llopart, M. Campell, R. Dinapoli, D. San Segundo, E. Pernigotti. IEEE Trans. Nucl. Sci. 49 (2002) 2279 ; N. Boudet, J.-F. Berar, L. Blanquart, P. Breugon, B. Caillot, J.-C. Clemens, I. Koudobine, P. Delpierre, C. Mouget, R. Potheau, I. Valin, Nucl. Instr. and Meth. Phys. Res. A 510 (2003) 41 ] are operating in the so-called 'single photon counting mode': Every X-ray quantum is directly converted into an electrical signal and counted by the detector system. Several prototype detectors in various geometries were produced, tested and established at different synchrotron beamlines worldwide. We explain the technology and present some recent highlights from various fields of applications.

  6. Monte Carlo simulation of the response functions of CdTe detectors to be applied in x-ray spectroscopy

    International Nuclear Information System (INIS)

    In this work, the energy response functions of a CdTe detector were obtained by Monte Carlo (MC) simulation in the energy range from 5 to 160 keV, using the PENELOPE code. In the response calculations the carrier transport features and the detector resolution were included. The computed energy response function was validated through comparison with experimental results obtained with 241Am and 152Eu sources. In order to investigate the influence of the correction by the detector response at diagnostic energy range, x-ray spectra were measured using a CdTe detector (model XR-100T, Amptek), and then corrected by the energy response of the detector using the stripping procedure. Results showed that the CdTe exhibits good energy response at low energies (below 40 keV), showing only small distortions on the measured spectra. For energies below about 80 keV, the contribution of the escape of Cd- and Te-K x-rays produce significant distortions on the measured x-ray spectra. For higher energies, the most important correction is the detector efficiency and the carrier trapping effects. The results showed that, after correction by the energy response, the measured spectra are in good agreement with those provided by a theoretical model of the literature. Finally, our results showed that the detailed knowledge of the response function and a proper correction procedure are fundamental for achieving more accurate spectra from which quality parameters (i.e., half-value layer and homogeneity coefficient) can be determined. - Highlights: • The response function of a CdTe detector was determined by Monte Carlo simulation. • The simulation takes into account all interaction process, the carrier transport and the Gaussian resolution. • The influence of different effects of spectral distortion was investigated. • CdTe detector was applied for x-ray spectroscopy. • The proper correction procedure is needed to achieve realistic x-ray spectra

  7. POLAR: A Space-borne X-Ray Polarimeter for Transient Sources

    CERN Document Server

    ,

    2010-01-01

    POLAR is a novel compact Compton X-ray polarimeter designed to measure the linear polarization of the prompt emission of Gamma Ray Bursts (GRB) and other strong transient sources such as soft gamma repeaters and solar flares in the energy range 50-500 keV. A detailed measurement of the polarization from astrophysical sources will lead to a better understanding of the source geometry and emission mechanisms. POLAR is expected to observe every year several GRBs with a minimum detectable polarization smaller than 10%, thanks to its large modulation factor, effective area, and field of view. POLAR consists of 1600 low-Z plastic scintillator bars, divided in 25 independent modular units, each read out by one flat-panel multi-anode photomultiplier. The design of POLAR is reviewed, and results of tests of one modular unit of the engineering and qualification model (EQM) of POLAR with synchrotron radiation are presented. After construction and testing of the full EQM, we will start building the flight model in 2011, ...

  8. Development of a CdTe pixel detector with a window comparator ASIC for high energy X-ray applications

    Science.gov (United States)

    Hirono, T.; Toyokawa, H.; Furukawa, Y.; Honma, T.; Ikeda, H.; Kawase, M.; Koganezawa, T.; Ohata, T.; Sato, M.; Sato, G.; Takagaki, M.; Takahashi, T.; Watanabe, S.

    2011-09-01

    We have developed a photon-counting-type CdTe pixel detector (SP8-01). SP8-01 was designed as a prototype of a high-energy X-ray imaging detector for experiments using synchrotron radiation. SP8-01 has a CdTe sensor of 500 μm thickness, which has an absorption efficiency of almost 100% up to 50 keV and 45% even at 100 keV. A full-custom application specific integrated circuit (ASIC) was designed as a readout circuit of SP8-01, which is equipped with a window-type discriminator. The upper discriminator realizes a low-background measurement, because X-ray beams from the monochromator contain higher-order components beside the fundamental X-rays in general. ASIC chips were fabricated with a TSMC 0.25 μm CMOS process, and CdTe sensors were bump-bonded to the ASIC chips by a gold-stud bonding technique. Beam tests were performed at SPring-8. SP8-01 detected X-rays up to 120 keV. The capability of SP8-01 as an imaging detector for high-energy X-ray synchrotron radiation was evaluated with its performance characteristics.

  9. Characterization of a Prototype TES-Based Anti-coincidence Detector for Use with Future X-ray Calorimeter Arrays

    Science.gov (United States)

    Busch, S. E.; Yoon, W. S.; Adams, J. S.; Bailey, C. N.; Bandler, S. R.; Chervenak, J. A.; Eckart, M. E.; Ewin, A. J.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Lee, S.-J.; Porst, J.-P.; Porter, F. S.; Sadleir, J. E.; Smith, S. J.; Sultana, M.

    2016-07-01

    For future X-ray observatories utilizing transition-edge sensor (TES) microcalorimeters, an anti-coincidence detector (anti-co) is required to discriminate X-ray (˜ 0.1-10 keV) signals from non-X-ray background events, such as ionizing particles. We have developed a prototype anti-co that utilizes TESs, which will be compatible with the TES focal-plane arrays planned for future X-ray observatories. This anti-co is based upon the cryogenic dark matter search II detector design. It is a silicon wafer covered with superconducting collection fins and TES microcalorimeters. Minimum ionizing particles deposit energy while passing through the silicon. The athermal phonons produced by these events are absorbed in the superconducting fins, breaking Cooper pairs. The resulting quasiparticles diffuse along the superconducting fin, producing a signal when they reach the TES. By determining a correlation between detections in the anti-co and the X-ray detector one can identify and flag these background events. We have fabricated and tested a single-channel prototype anti-co device on a 1.5 × 1.9 cm^2 chip. We have measured the signals in this device from photons of several energies between 1.5 and 60 keV, as well as laboratory background events, demonstrating a threshold ˜ 100 times lower than is needed to detect minimum ionizing particles.

  10. Characterization of a Prototype TES-Based Anti-coincidence Detector for Use with Future X-ray Calorimeter Arrays

    Science.gov (United States)

    Busch, S. E.; Yoon, W. S.; Adams, J. S.; Bailey, C. N.; Bandler, S. R.; Chervenak, J. A.; Eckart, M. E.; Ewin, A. J.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Lee, S.-J.; Porst, J.-P.; Porter, F. S.; Sadleir, J. E.; Smith, S. J.; Sultana, M.

    2015-12-01

    For future X-ray observatories utilizing transition-edge sensor (TES) microcalorimeters, an anti-coincidence detector (anti-co) is required to discriminate X-ray (˜ 0.1-10 keV) signals from non-X-ray background events, such as ionizing particles. We have developed a prototype anti-co that utilizes TESs, which will be compatible with the TES focal-plane arrays planned for future X-ray observatories. This anti-co is based upon the cryogenic dark matter search II detector design. It is a silicon wafer covered with superconducting collection fins and TES microcalorimeters. Minimum ionizing particles deposit energy while passing through the silicon. The athermal phonons produced by these events are absorbed in the superconducting fins, breaking Cooper pairs. The resulting quasiparticles diffuse along the superconducting fin, producing a signal when they reach the TES. By determining a correlation between detections in the anti-co and the X-ray detector one can identify and flag these background events. We have fabricated and tested a single-channel prototype anti-co device on a 1.5 × 1.9 cm^2 chip. We have measured the signals in this device from photons of several energies between 1.5 and 60 keV, as well as laboratory background events, demonstrating a threshold ˜ 100 times lower than is needed to detect minimum ionizing particles.

  11. Pulse pileup statistics for energy discriminating photon counting x-ray detectors

    International Nuclear Information System (INIS)

    Purpose: Energy discriminating photon counting x-ray detectors can be subject to a wide range of flux rates if applied in clinical settings. Even when the incident rate is a small fraction of the detector's maximum periodic rate N0, pulse pileup leads to count rate losses and spectral distortion. Although the deterministic effects can be corrected, the detrimental effect of pileup on image noise is not well understood and may limit the performance of photon counting systems. Therefore, the authors devise a method to determine the detector count statistics and imaging performance. Methods: The detector count statistics are derived analytically for an idealized pileup model with delta pulses of a nonparalyzable detector. These statistics are then used to compute the performance (e.g., contrast-to-noise ratio) for both single material and material decomposition contrast detection tasks via the Cramer-Rao lower bound (CRLB) as a function of the detector input count rate. With more realistic unipolar and bipolar pulse pileup models of a nonparalyzable detector, the imaging task performance is determined by Monte Carlo simulations and also approximated by a multinomial method based solely on the mean detected output spectrum. Photon counting performance at different count rates is compared with ideal energy integration, which is unaffected by count rate. Results: The authors found that an ideal photon counting detector with perfect energy resolution outperforms energy integration for our contrast detection tasks, but when the input count rate exceeds 20%N0, many of these benefits disappear. The benefit with iodine contrast falls rapidly with increased count rate while water contrast is not as sensitive to count rates. The performance with a delta pulse model is overoptimistic when compared to the more realistic bipolar pulse model. The multinomial approximation predicts imaging performance very close to the prediction from Monte Carlo simulations. The monoenergetic image

  12. Performance evaluation of flat panel detector in x-ray fluoroscopy

    International Nuclear Information System (INIS)

    increases the input dose during magnification to maintain image quality in much the same way as in a conventional fluoro system. Flat panel detectors in x-ray fluoroscopy systems can provide similar or better images than achievable with conventional IIs. There is no obvious distortion, typical patient dose is low and image quality is good. Copyright (2004) Australasian College of Physical Scientists and Engineers in Medicine

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

    Science.gov (United States)

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

    2016-09-01

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

  14. Thin-film-based scintillators for hard x-ray microimaging detectors: the ScinTAX Project

    Science.gov (United States)

    Rack, A.; Cecilia, A.; Douissard, P.-A.; Dupré, K.; Wesemann, V.; Baumbach, T.; Couchaud, M.; Rochet, X.; Riesemeier, H.; Radtke, M.; Martin, T.

    2014-09-01

    The project ScinTAX developed novel thin scintillating films for the application in high performance X-ray imaging and subsequent introduced new X-ray detectors to the market. To achieve this aim lutetium orthosilicate (LSO) scintillators doped with different activators were grown successfully by liquid phase epitaxy. The high density of LSO (7.4 g/cm3), the effective atomic number (65.2) and the high light yield make this scintillator highly applicable for indirect X-ray detection in which the ionizing radiation is converted into visible light and then registered by a digital detector. A modular indirect detection system has been developed to fully exploit the potential of this thin film scintillator for radiographic and tomographic imaging. The system is compatible for high-resolution imaging with moderate dose as well as adaptable to intense high-dose applications where radiation hard microimaging detectors are required. This proceedings article shall review the achieved performances and technical details on this high-resolution detector system which is now available. A selected example application demonstrates the great potential of the optimized detector system for hard X-ray microimaging, i.e. either to improve image contrast due to the availability of efficient thin crystal films or to reduce the dose to the sample.

  15. X-ray photon correlation spectroscopy using a fast pixel array detector with a grid mask resolution enhancer

    International Nuclear Information System (INIS)

    The performance of a fast pixel array detector with a grid mask resolution enhancer has been demonstrated for X-ray photon correlation spectroscopy experiments. The performance of a fast pixel array detector with a grid mask resolution enhancer has been demonstrated for X-ray photon correlation spectroscopy (XPCS) measurements to investigate fast dynamics on a microscopic scale. A detecting system, in which each pixel of a single-photon-counting pixel array detector, PILATUS, is covered by grid mask apertures, was constructed for XPCS measurements of silica nanoparticles in polymer melts. The experimental results are confirmed to be consistent by comparison with other independent experiments. By applying this method, XPCS measurements can be carried out by customizing the hole size of the grid mask to suit the experimental conditions, such as beam size, detector size and sample-to-detector distance

  16. X-ray Emission from Solar Flares

    Indian Academy of Sciences (India)

    Rajmal Jain; Malini Aggarwal; Raghunandan Sharma

    2008-03-01

    Solar X-ray Spectrometer (SOXS), the first space-borne solar astronomy experiment of India was designed to improve our current understanding of X-ray emission from the Sun in general and solar flares in particular. SOXS mission is composed of two solid state detectors, viz., Si and CZT semiconductors capable of observing the full disk Sun in X-ray energy range of 4–56 keV. The X-ray spectra of solar flares obtained by the Si detector in the 4–25 keV range show evidence of Fe and Fe/Ni line emission and multi-thermal plasma. The evolution of the break energy point that separates the thermal and non-thermal processes reveals increase with increasing flare plasma temperature. Small scale flare activities observed by both the detectors are found to be suitable to heat the active region corona; however their location appears to be in the transition region.

  17. Evaluation of the x-ray response of a position-sensitive microstrip detector with an integrated readout chip

    International Nuclear Information System (INIS)

    The performance of an SVX silicon microstrip detector and its compatible integrated readout chip have been evaluated in response to Rh Kα x-rays (average energy 20.5 keV). The energy and spatial discrimination capabilities, efficient data management and fast readout rates make it an attractive alternative to the CCD and PDA detectors now being offered for x-ray position sensitive diffraction and EXAFS work. The SVX system was designed for high energy physics applications and thus further development of the existing system is required to optimize it for use in practical x-ray experiments. For optimum energy resolution the system noise must be decreased to its previously demonstrated low levels of 2 keV FWHM at 60 keV or less, and the data handling rate of the computer must be increased. New readout chips are now available that offer the potential of better performance. 15 refs., 7 figs

  18. Detection sensibility study from a portable EDXRF system with a Si-PIN detector and an X ray tube

    International Nuclear Information System (INIS)

    Energy Dispersive X Ray Fluorescence (EDXRF) technique was used for the sensibility variation study of a Si-PIN detector. For sample excitation a portable mini x ray tube (Ag target, 4W), under different operational conditions was used with the objective of optimize the analytical sensibility for trace elements determinations in environmental samples. The sensibility curves were obtained by standard reference materials irradiation on thin films from MicroMatter Inc. With these curves the concentration of two certified reference materials SRM1832 and SRM1833 were determined for validation purpose. The measurement time was 200s. Were used in the detector Al and Pb collimators. On the end of the X ray tube was used Mo filter. The best results were verified for Al and Pb collimator operating at 25kV and 20μA. (author)

  19. X-ray absorption spectroscopy of diluted system by undulator photon source and multi-element solid-state detector

    CERN Document Server

    Tanida, H

    2001-01-01

    In order to measure the extended X-ray absorption fine structure (EXAFS) spectrum of an ultra-diluted system, an optics and detector control system for a synchrotron radiation beamline is developed. The undulator gap width is continuously tuned to obtain the maximum X-ray photon flux during the energy scan for the EXAFS measurement. A piezoelectric translator optimizes the parallelism of the double crystal in a monochromator at each measurement point to compensate for mechanical errors of the monochromator, resulting in a smooth and intense X-ray photon flux during the measurement. For a detection of a weak fluorescence signal from diluted samples, a 19-element solid-state detector and digital signal processor are used. A K-edge EXAFS spectrum of iron in a myoglobin aqueous solution with a concentration of 5.58 parts per million was obtained by this system.

  20. Characteristic x-ray spectra of sodium and magnesium measured at room temperature using mercuric iodide detectors

    International Nuclear Information System (INIS)

    Mercuric iodide detectors, operating at room temperature with the FET of the first stage of amplification cooled with a two-stage Peltier element, have been used to detect low-energy x rays from light elements excited by 2.0- and 6.1-MeV α particles. X-ray lines from Na (1.04 keV) and Mg (1.25 keV) have been seen for the first time with room-temperature energy-dispersive detectors. A resolution of 390 eV at 1.25 keV was obtained. Further improvement of the resolution is believed to be achievable. However, even the present characteristics are adequate for many applications in x-ray fluorescence and elemental analysis. Several such possible applications are suggested

  1. CCD[charge-coupled device]-based synchrotron x-ray detector for protein crystallography: Performance projected from an experiment

    International Nuclear Information System (INIS)

    The intense x radiation from a synchrotron source could, with a suitable detector, provide a complete set of diffraction images from a protein crystal before the crystal is damaged by radiation (2 to 3 min). An area detector consisting of a 40 mm dia. x-ray fluorescing phosphor, coupled with an image intensifier and lens to a CCD image sensor, was developed to determine the effectiveness of such a detector in protein crystallography. The detector was used in an experiment with a rotating anode x-ray generator. Diffraction patterns from a lysozyme crystal obtained with this detector are compared to those obtained with film. The two images appear to be virtually identical. The flux of 104 x-ray photons/s was observed on the detector at the rotating anode generator. At the 6-GeV synchrotron being designed at Argonne, the flux on an 80 x 80 mm2 detector is expected to be >109 photons/s. The projected design of such a synchrotron detector shows that a diffraction-peak count >106 could be obtained in ∼0.5 s. With an additional ∼0.5 s readout time of a 512 x 512 pixel CCD, the data acquisition time per frame would be ∼1 s so that ninety 10 diffraction images could be obtained, with approximately 1% precision, in less than 3 min

  2. Hybrid deterministic and stochastic x-ray transport simulation for transmission computed tomography with advanced detector noise model

    Science.gov (United States)

    Popescu, Lucretiu M.

    2016-03-01

    We present a model for simulation of noisy X-ray computed tomography data sets. The model is made of two main components, a photon transport simulation component that generates the noiseless photon field incident on the detector, and a detector response model that takes as input the incident photon field parameters and given the X-ray source intensity and exposure time can generate noisy data sets, accordingly. The photon transport simulation component combines direct ray-tracing of polychromatic X-rays for calculation of transmitted data, with Monte Carlo simulation for calculation of the scattered-photon data. The Monte Carlo scatter simulation is accelerated by implementing particle splitting and importance sampling variance reduction techniques. The detector-incident photon field data are stored as energy expansion coefficients on a refined grid that covers the detector area. From these data the detector response model is able to generate noisy detector data realizations, by reconstituting the main parameters that describe each detector element response in statistical terms, including spatial correlations. The model is able to generate very fast, on the fly, CT data sets corresponding to different radiation doses, as well as detector response characteristics, facilitating data management in extensive optimization studies by reducing the computation time and storage space demands.

  3. X-ray observations of MeV electron precipitation with a balloon-borne germanium spectrometer

    Science.gov (United States)

    Millan, R. M.; Lin, R. P.; Smith, D. M.; Lorentzen, K. R.; McCarthy, M. P.

    2002-12-01

    The high-resolution germanium detector aboard the MAXIS (MeV Auroral X-ray Imaging and Spectroscopy) balloon payload detected nine X-ray bursts with significant flux extending above 0.5 MeV during an 18 day flight over Antarctica. These minutes-to-hours-long events are characterized by an extremely flat spectrum (~E-2) similar to the first MeV event discovered in 1996, indicating that the bulk of parent precipitating electrons is at relativistic energies. The MeV bursts were detected between magnetic latitudes 58°-68° (L-values of 3.8-6.7) but only in the late afternoon/dusk sectors (14:30-00:00 MLT), suggesting scattering by EMIC (electromagnetic ion cyclotron) waves as a precipitation mechanism. We estimate the average flux of precipitating E >= 0.5 MeV electrons to be ~360 cm-2s-1, corresponding to about 5 × 1025 such electrons precipitated during the eight days at L = 3.8-6.7, compared to ~2 × 1025 trapped 0.5-3.6 MeV electrons estimated from dosimeter measurements on a GPS spacecraft. These observations show that MeV electron precipitation events are a primary loss mechanism for outer zone relativistic electrons.

  4. A 3D CZT hard x-ray polarimeter for a balloon-borne payload

    DEFF Research Database (Denmark)

    Caroli, E.; Alvarez, J. M.; Auricchio, N.;

    2012-01-01

    status of the Crab pulsar, i.e. the polarization level and direction. The detector with 3D spatial resolution is based on a CZT spectrometer in a highly segmented configuration designed to operate as a high performance scattering polarimeter. We discuss different configurations based on recent...

  5. Characterization of a scintillating GEM detector with low energy x-rays.

    Science.gov (United States)

    Seravalli, E; de Boer, M R; Geurink, F; Huizenga, J; Kreuger, R; Schippers, J M; van Eijk, C W E

    2008-11-01

    A two-dimensional position-sensitive dosimetry system based on a scintillating gas detector is being developed with the aim of using it for pre-treatment verification of dose distributions in charged particle therapy. The dosimetry system consists of a chamber filled with an Ar/CF(4) scintillating gas mixture, inside which two cascaded gas electron multipliers (GEMs) are mounted. A GEM is a thin kapton foil with copper cladding structured with a regular pattern of sub-mm holes. In such a system, light quanta are emitted by the scintillating gas mixture during the electron avalanches in the GEM holes when radiation traverses the detector. The light intensity distribution is proportional to the energy deposited in the detector's sensitive volume by the beam. In the present work, we investigated the optimization of the scintillating GEM detector light yield. The light quanta are detected by means of a CCD camera or a photomultiplier tube coupled to a monochromator. The GEM charge signal is measured simultaneously. We have found that with 60 microm diameter double conical GEM holes, a brighter light signal and a higher electric signal are obtained than with 80 microm diameter holes. With an Ar + 8% CF(4) volume concentration, the highest voltage across the GEMs and the largest light and electric signals were reached. Moreover, we have found that the emission spectrum of Ar/CF(4) is independent of (1) the voltages applied across the GEMs, (2) the x-ray beam intensity and (3) the GEM hole diameter. On the other hand, the ratio of Ar to CF(4) peaks in the spectrum changes when the concentration of the latter gas is varied. PMID:18854612

  6. High-rate X-ray spectroscopy using a Silicon Drift Detector and a charge preamplifier

    International Nuclear Information System (INIS)

    In this work, we present the results achieved in the experimental characterization of a Silicon Drift Detector (SDD) in X-ray spectroscopy measurements at high counting rates. The main goal of the work is to verify that high peak stability can be achieved when using an SDD with the input JFET and when the feedback capacitor directly integrated on the detector and a charge preamplifier configuration. In the proposed circuit, the SDD anode voltage is stabilized by means of a low-frequency feedback loop which operates according to the 'drain feedback' technique. The stabilization of the anode voltage is necessary to guarantee the stabilization of the feedback capacitor; moreover, the implemented design allows to obtain a sufficiently fixed decay time constant of the preamplifier with respect to rate variations. In the characterization of the preamplifier with an SDD, a Mn-Kalpha peak shift within ±0.05% (i.e. below 6 eV) has been achieved changing the rate from few kcounts/s up to several hundred kcounts/s. The same circuit has been modified and then employed to be used with an SDD without feedback capacitor, exploiting a parasitic capacitor between anode and a neighbour ring as feedback capacitor. The results achieved with this configuration are also presented in this work

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

    CERN Document Server

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

    2013-01-01

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

  8. SERENDIPITOUS DETECTION OF X-RAY EMISSION FROM THE HOT BORN-AGAIN CENTRAL STAR OF THE PLANETARY NEBULA K 1-16

    International Nuclear Information System (INIS)

    We report the serendipitous detection of point-like X-ray emission from the hot, PG1159-type central star of the planetary nebula (CSPN) K 1-16 by the XMM-Newton and Chandra X-Ray Observatories. The CSPN lies superimposed on a galaxy cluster that includes an X-ray-bright quasar, but we have successfully isolated the CSPN X-ray emission from the strong diffuse background contributed by the quasar and intracluster gas. We have modeled the XMM-Newton and Chandra X-ray data, taking advantage of the contrasting detection efficiencies of the two observatories to better constrain the low-energy spectral response of Chandra's Advanced CCD Imaging Spectrometer. We find that the CSPN X-ray spectrum is well characterized by the combination of a non-local thermodynamic equilibrium model atmosphere with T* ∼ 135 kK and a carbon-rich, optically thin thermal plasma with TX ∼ 1 MK. These results for X-ray emission from the K 1-16 CSPN, combined with those obtained for other PG1159-type objects, lend support to the 'born-again' scenario for Wolf-Rayet and PG1159 CSPNe, wherein a late helium shell flash dredges up carbon-rich intershell material and ejects this material into the circumstellar environment.

  9. Position sensitive and energy dispersive x-ray detector based on silicon strip detector technology

    International Nuclear Information System (INIS)

    A new position sensitive detector with a global energy resolution for the entire detector of about 380 eV FWHM for 8.04 keV line at ambient temperature is presented. The measured global energy resolution is defined by the energy spectra summed over all strips of the detector, and thus it includes electronic noise of the front-end electronics, charge sharing effects, matching of parameters across the channels and other system noise sources. The target energy resolution has been achieved by segmentation of the strips to reduce their capacitance and by careful optimization of the front-end electronics. The key design aspects and parameters of the detector are discussed briefly in the paper. Excellent noise and matching performance of the readout ASIC and negligible system noise allow us to operate the detector with a discrimination threshold as low as 1 keV and to measure fluorescence radiation lines of light elements, down to Al Kα  of 1.49 keV, simultaneously with measurements of the diffraction patterns. The measurement results that demonstrate the spectrometric and count rate performance of the developed detector are presented and discussed in the paper

  10. Measurement of the electrical properties of a polycrystalline cadmium telluride for direct conversion flat panel x-ray detector

    International Nuclear Information System (INIS)

    Cadmium telluride (CdTe) is one of the best candidate direct conversion material for medical X-ray application because it satisfies the requirements of direct conversion x-ray material such as high atomic absorption, density, bandgap energy, work fuction, and resistivity. With such properties, single crystal CdTe exhibits high quantum efficiency and charge collection efficiency. However, for the development of low-cost large area detector, the study of the improvement of polycrystalline CdTe property is desirable. In this study, in order to improve the properties of polycrystalline CdTe, we produced polycrystalline CdTe with different kinds of raw materials, high purity Cd and Te powder compounds and bulk CdTe compound synthesized from single crystal CdTe. The electric properties including resistivity, x-ray sensitivity, and charge transport properties were investigated. As a result, polycrystalline CdTe exhibited simular level of resistivity and x-ray sensitivity to single crystal CdTe. The carrier transport properties of polycrystalline CdTe showed poorer properties than those of single crystal CdTe due to significant charge trapping. However, the polycrystalline CdTe fabricated with bulk CdTe compound synthesized from single crystal CdTe showed better charge transport properties than the polycrystalline CdTe fabricated with CdTe powder compounds. This is suitable for diagnostic x-ray detectors, especially for digital fluoroscopy

  11. Measurement 20-200 keV hard X-ray based on CdTe detector in EAST Tokamak

    International Nuclear Information System (INIS)

    Background: Accurate and quantitative measurement of plasma radiation is a key issue to Tokamak, toroidal magnetic confinement device. The radiations from Tokamak cover large energy range. Driven by the determination of the obtaining of hard X-ray spectra, a new system based on a high performance CdTe detector was built up in EAST Tokamak, the first non-circle cross-section in the world. Purpose: Introduces the device of hard X-ray diagnosis system in the EAST Tokamak on the Port A. The system can measure the plasma hard X-ray (20-200 keV) spectra under different discharge conditions, including Ohmical shot and Lower Hybrid Current Drive (LHCD) shot. The research of high speed electron which produced by LHCD is also the aim of the new system. Methods: A high performance CdTe detector was using in EAST Tokamak to measure the hard X-ray (20-200 keV) spectra. Results: The results show that the new system based on a high performance CdTe can meet the requirements for measuring the EAST Tokamak. Conclusions: A preliminary experimental result showed that the system can meet the requirements for measuring the X-ray bremsstrahlung of plasma in the energy range from 20 to 200 keV Calibration result and typical measurement result on EAST are present in this paper. (authors)

  12. The parallax calculation method and coordinate corrections for X-ray beams in the detectors based on straw drift tubes

    International Nuclear Information System (INIS)

    In this work we propose a model for solving X-structural analysis-like problems, connected with small angle scattering, which calculates the angle and specifies the coordinate of incoming thin X-ray beam while working with detectors based on straw drift tubes with cathode read-out of information

  13. Development of a DAQ system for a plasma display panel-based X-ray detector (PXD)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hakjae [School of Biomedical Engineering, Korea University, Seoul (Korea, Republic of); Research Institute of Health Science, Korea University, Seoul (Korea, Republic of); Jung, Young-Jun [School of Biomedical Engineering, Korea University, Seoul (Korea, Republic of); Eom, Sangheum [Plasma Technology Research Center, National Fusion Research Institute, Gunsan-si (Korea, Republic of); Kang, Jungwon [Department of Electronics and Electrical Engineering, Dankook University, Yongin, Gyeonggi (Korea, Republic of); Lee, Kisung, E-mail: kisung@korea.ac.kr [School of Biomedical Engineering, Korea University, Seoul (Korea, Republic of)

    2015-06-01

    Recently, a novel plasma display panel (PDP)-based X-ray detector (PXD) was developed. The goal of this study is to develop a data acquisition system for use with the PXD as an imaging detector. Since the prototype detector does not have any barrier ribs or a switching device in a detector pixel, a novel pixelation scheme—the line-scan method—is developed for this new detector. To implement line scanning, a multichannel high-voltage switching circuit and a multichannel charge-acquisition circuit are developed. These two circuits are controlled by an FPGA-based digital signal processing board, from which the information about the charge and position of each pixel can be sent to a PC. FPGA-based baseline compensation and switching noise rejection algorithms are used to improve the signal-to-noise ratio (SNR). The characteristic curve of the entire PXD system is acquired, and the correlation coefficients between the X-ray dose, and the signal intensity and the SNR were determined to be approximately 0.99 and 52.9, respectively. - Highlights: • We developed a data acquisition circuit for a novel X-ray imaging detector. • Line scan, noise rejection, and data transmission methods have been implemented by the FPGA. • The linearity and SNR of the proposed detector system have been measured quantitatively.

  14. Development of a DAQ system for a plasma display panel-based X-ray detector (PXD)

    International Nuclear Information System (INIS)

    Recently, a novel plasma display panel (PDP)-based X-ray detector (PXD) was developed. The goal of this study is to develop a data acquisition system for use with the PXD as an imaging detector. Since the prototype detector does not have any barrier ribs or a switching device in a detector pixel, a novel pixelation scheme—the line-scan method—is developed for this new detector. To implement line scanning, a multichannel high-voltage switching circuit and a multichannel charge-acquisition circuit are developed. These two circuits are controlled by an FPGA-based digital signal processing board, from which the information about the charge and position of each pixel can be sent to a PC. FPGA-based baseline compensation and switching noise rejection algorithms are used to improve the signal-to-noise ratio (SNR). The characteristic curve of the entire PXD system is acquired, and the correlation coefficients between the X-ray dose, and the signal intensity and the SNR were determined to be approximately 0.99 and 52.9, respectively. - Highlights: • We developed a data acquisition circuit for a novel X-ray imaging detector. • Line scan, noise rejection, and data transmission methods have been implemented by the FPGA. • The linearity and SNR of the proposed detector system have been measured quantitatively

  15. Sensitivity measurements of a microchannel plate intensified x-ray detector in the 100 - 1500 eV photon energy range (abstract)

    International Nuclear Information System (INIS)

    Microchannel plate intensified (MPI) x-ray detectors are commonly used for imaging and spectral measurements in the 100 - 1500 eV photon energy range. Using a laser-produced plasma x-ray source, we measured the integrated detector response versus incident x-ray intensity and the relative efficiency versus photon energy of a MPI x-ray detector. Two identical 2000 lines/mm transmission grating spectrometers simultaneously record broadband plasma source emission from a tantalum target. The relative efficiency was determined by comparing the spectrum recorded with an absolutely calibrated x-ray CCD reference detector on one spectrometer to the spectrum recorded with a MPI x-ray detector on the other spectrometer. The integrated detector response versus incident x-ray intensity was measured by simultaneously illuminating the CCD reference detector and the MPI detector with step-wedge-filtered magnesium plasma emission. The aluminum step wedge x-ray filters pass the 1s - 2p emission lines of H-like Mg at 1470 eV and the 1s2 - 1s2p emission lines of He-like Mg at 1350 eV, and provide a four order of magnitude range in incident intensity on the detectors.copyright 1999 American Institute of Physics

  16. Detector, collimator and real-time reconstructor for a new scanning-beam digital x-ray (SBDX) prototype

    Science.gov (United States)

    Speidel, Michael A.; Tomkowiak, Michael T.; Raval, Amish N.; Dunkerley, David A. P.; Slagowski, Jordan M.; Kahn, Paul; Ku, Jamie; Funk, Tobias

    2015-03-01

    Scanning-beam digital x-ray (SBDX) is an inverse geometry fluoroscopy system for low dose cardiac imaging. The use of a narrow scanned x-ray beam in SBDX reduces detected x-ray scatter and improves dose efficiency, however the tight beam collimation also limits the maximum achievable x-ray fluence. To increase the fluence available for imaging, we have constructed a new SBDX prototype with a wider x-ray beam, larger-area detector, and new real-time image reconstructor. Imaging is performed with a scanning source that generates 40,328 narrow overlapping projections from 71 x 71 focal spot positions for every 1/15 s scan period. A high speed 2-mm thick CdTe photon counting detector was constructed with 320x160 elements and 10.6 cm x 5.3 cm area (full readout every 1.28 μs), providing an 86% increase in area over the previous SBDX prototype. A matching multihole collimator was fabricated from layers of tungsten, brass, and lead, and a multi-GPU reconstructor was assembled to reconstruct the stream of captured detector images into full field-of-view images in real time. Thirty-two tomosynthetic planes spaced by 5 mm plus a multiplane composite image are produced for each scan frame. Noise equivalent quanta on the new SBDX prototype measured 63%-71% higher than the previous prototype. X-ray scatter fraction was 3.9-7.8% when imaging 23.3-32.6 cm acrylic phantoms, versus 2.3- 4.2% with the previous prototype. Coronary angiographic imaging at 15 frame/s was successfully performed on the new SBDX prototype, with live display of either a multiplane composite or single plane image.

  17. Dose distribution around a needle-like anode X-ray tube: dye-film vs. planar thermoluminescent detectors.

    Science.gov (United States)

    Budzanowski, M; Olko, P; Marczewska, B; Czopyk, L; Slapa, M; Stras, W; Traczyk, M; Talejko, M

    2006-01-01

    The dosimetry around the X-ray tube with a needle-like anode (NAXT), developed at the Institute of Nuclear Studies, for interstitial brachytherapy has been performed using (1) dye films (Gafchromic XR-T), (2) large-area thermoluminescent (TL) detectors--prepared either by gluing TL powder onto thin Al foil (so-called planar detectors with spatial resolution of 0.1 mm) and (3) miniature (2 mm diameter and 0.5 mm thick) TL detectors. The measurements were performed in following geometries. (1) Needle inside a PMMA cylinder--the planar TL detector mounted on the surface of the cylinder. (2) Needle inside a thick block of PMMA and TL detector mounted vertically 7 mm from needle axis. TL detectors were read with the planar (2D) thermoluminescence reader, developed at IFJ, with a sensitive CCD (charge couple device) camera. Gafchromic films were evaluated with a system based on Agfa Arcus 1200 scanner and calibrated with X rays (35 kV) filtered with 0.03 mm Mo and with Co-60 photons. The intensity distribution of TL light on the planar detector was calibrated in terms of absorbed dose to water, using (137)Cs gamma-rays. TL planar detectors seem to be a promising tool for 2D dosimetry of miniature X-ray sources. Obtained results for TLDs and Gafchromic films seem to be comparable but differences have been found. Both methods are useful for measurements of dose distribution around the NAXT X-rays source. PMID:16614087

  18. Spectroscopic imaging using Ge and CdTe based detector systems for hard x-ray applications.

    OpenAIRE

    Astromskas, Vytautas

    2016-01-01

    Third generation synchrotron facilities such as the Diamond Light Source (DLS) have a wide range of experiments performed for a wide range of science fields. The DLS operates at energies up to 150 keV which introduces great challenges to radiation detector technology. This work focuses on the requirements that the detector technology faces for X-ray Absorption Fine Structure (XAFS) and powder diffraction experiments in I12 and I15 beam lines, respectively. A segmented HPGe demonstrator det...

  19. Dynamic defectoscopy with flat panel and CdTe Timepix X-ray detectors combined with an optical camera

    Czech Academy of Sciences Publication Activity Database

    Vavřík, Daniel; Fauler, A.; Fiederle, M.; Jandejsek, Ivan; Jakůbek, J.; Tureček, D.; Zwerger, A.

    2013-01-01

    Roč. 8, April (2013), C04009. ISSN 1748-0221. [International Workshop on Radiation Imaging Detector s /14./. Figueira da Foz, Coimbra, 01.07.2012-05.07.2012] R&D Projects: GA ČR(CZ) GA103/09/2101 Institutional support: RVO:68378297 Keywords : X-ray digital radiography * fracture mechanics * crack path * X-ray defectoscopy Subject RIV: JM - Building Engineering Impact factor: 1.526, year: 2013 http://iopscience.iop.org/1748-0221/8/04/C04009/

  20. Monte Carlo simulation of the response functions of Cd Te detectors to be applied in X-rays spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tomal, A. [Universidade Federale de Goias, Instituto de Fisica, Campus Samambaia, 74001-970, Goiania, (Brazil); Lopez G, A. H.; Santos, J. C.; Costa, P. R., E-mail: alessandra_tomal@yahoo.com.br [Universidade de Sao Paulo, Instituto de Fisica, Rua du Matao Travessa R. 187, Cidade Universitaria, 05508-090 Sao Paulo (Brazil)

    2014-08-15

    In this work, the energy response functions of a Cd Te detector were obtained by Monte Carlo simulation in the energy range from 5 to 150 keV, using the Penelope code. The response functions simulated included the finite detector resolution and the carrier transport. The simulated energy response matrix was validated through comparison with experimental results obtained for radioactive sources. In order to investigate the influence of the correction by the detector response at diagnostic energy range, x-ray spectra were measured using a Cd Te detector (model Xr-100-T, Amptek), and then corrected by the energy response of the detector using the stripping procedure. Results showed that the Cd Te exhibit good energy response at low energies (below 40 keV), showing only small distortions on the measured spectra. For energies below about 70 keV, the contribution of the escape of Cd- and Te-K x-rays produce significant distortions on the measured x-ray spectra. For higher energies, the most important correction is the detector efficiency and the carrier trapping effects. The results showed that, after correction by the energy response, the measured spectra are in good agreement with those provided by different models from the literature. Finally, our results showed that the detailed knowledge of the response function and a proper correction procedure are fundamental for achieve more accurate spectra from which several qualities parameters (i.e. half-value layer, effective energy and mean energy) can be determined. (Author)