Science.gov

Sample records for position-sensitive detector studies

  1. Position-sensitive superconductor detectors

    NASA Astrophysics Data System (ADS)

    Kurakado, M.; Taniguchi, K.

    2016-12-01

    Superconducting tunnel junction (STJ) detectors and superconducting transition- edge sensors (TESs) are representative superconductor detectors having energy resolutions much higher than those of semiconductor detectors. STJ detectors are thin, thereby making it suitable for detecting low-energy X rays. The signals of STJ detectors are more than 100 times faster than those of TESs. By contrast, TESs are microcalorimeters that measure the radiation energy from the change in the temperature. Therefore, signals are slow and their time constants are typically several hundreds of μs. However, TESs possess excellent energy resolutions. For example, TESs have a resolution of 1.6 eV for 5.9-keV X rays. An array of STJs or TESs can be used as a pixel detector. Superconducting series-junction detectors (SSJDs) comprise multiple STJs and a single-crystal substrate that acts as a radiation absorber. SSJDs are also position sensitive, and their energy resolutions are higher than those of semiconductor detectors. In this paper, we give an overview of position-sensitive superconductor detectors.

  2. High speed curved position sensitive detector

    DOEpatents

    Hendricks, Robert W.; Wilson, Jack W.

    1989-01-01

    A high speed curved position sensitive porportional counter detector for use in x-ray diffraction, the detection of 5-20 keV photons and the like. The detector employs a planar anode assembly of a plurality of parallel metallic wires. This anode assembly is supported between two cathode planes, with at least one of these cathode planes having a serpentine resistive path in the form of a meander having legs generally perpendicular to the anode wires. This meander is produced by special microelectronic fabrication techniques whereby the meander "wire" fans outwardly at the cathode ends to produce the curved aspect of the detector, and the legs of the meander are small in cross-section and very closely spaced whereby a spatial resolution of about 50 .mu.m can be achieved. All of the other performance characteristics are about as good or better than conventional position sensitive proportional counter type detectors. Count rates of up to 40,000 counts per second with 0.5 .mu.s shaping time constants are achieved.

  3. Position sensitive detectors for synchrotron radiation studies: the tortoise and the hare?

    NASA Astrophysics Data System (ADS)

    Lewis, Rob

    2003-11-01

    The huge gulf between the high photon fluxes available from synchrotrons and the capabilities of detectors to measure the resulting photon, electron or ion signals is well known. Whilst accelerator technology continues to advance at a rapid pace, it is detector performance which represents the limiting factor for many synchrotron experiments. In some cases there are still single channel counting detectors based on 40-year-old designs operational on synchrotron beamlines. The dream of many researchers is a detector which is able to simultaneously image and perform spectroscopy at the required data rates. A solution is the massive integration of parallel electronics into detectors on a pixel by pixel basis. These ideas have been in gestation for very many years awaiting sufficient funding, nevertheless, several prototypes are now at the testing stage. The current status of these and other detector developments targeted at synchrotron science are briefly reviewed.

  4. Two-dimensional position sensitive radiation detectors

    DOEpatents

    Mihalczo, J.T.

    1994-02-22

    Nuclear reaction detectors capable of position sensitivity with submillimeter resolution in two dimensions are each provided by placing arrays of scintillation or wavelength shifting optical fibers formed of a plurality of such optical fibers in a side-by-side relationship in X and Y directions with a layer of nuclear reactive material operatively associated with surface regions of the optical fiber arrays. Each nuclear reaction occurring in the layer of nuclear reactive material produces energetic particles for simultaneously providing a light pulse in a single optical fiber in the X oriented array and in a single optical fiber in the Y oriented array. These pulses of light are transmitted to a signal producing circuit for providing signals indicative of the X-Y coordinates of each nuclear event. 6 figures.

  5. Two-dimensional position sensitive radiation detectors

    DOEpatents

    Mihalczo, John T.

    1994-01-01

    Nuclear reaction detectors capable of position sensitivity with submillimeter resolution in two dimensions are each provided by placing arrays of scintillation or wave length shifting optical fibers formed of a plurality of such optical fibers in a side-by-side relationship in X and Y directions with a layer of nuclear reactive material operatively associated with surface regions of the optical fiber arrays. Each nuclear reaction occurring in the layer of nuclear reactive material produces energetic particles for simultaneously providing a light pulse in a single optical fiber in the X oriented array and in a single optical fiber in the Y oriented array. These pulses of light are transmitted to a signal producing circuit for providing signals indicative of the X-Y coordinates of each nuclear event.

  6. Background Studies of a Position Sensitive CdZnTe X-ray Detector at Balloon Altitudes

    NASA Astrophysics Data System (ADS)

    Slavis, K.; Dowkontt, P.; Epstein, J.; Hink, P.; Matteson, J.; Duttweiler, F.; Huszar, G.; Leblanc, P.; Skelton, R.; Stephan, E.

    1999-04-01

    Cadmium Zinc Telluride (CZT) is a room temperature semiconductor detector well suited for high energy X-ray astronomy. As part of the High Energy X-ray Imaging Spectrometer (HEXIS) development, we flew a position sensitive CZT detector on two balloon flights using seven shielding schemes to study the background properties of the CZT detector. Passive, active and hybrid passive-active shields were used on the cross-strip detector as well as on a standard planar CZT flown along side the cross-strip CZT for comparison. The cross-strip detector utilizes our recently developed, novel electrode configuration that improves interaction localization and depth of interaction (DOI) determination. During the flight, shield pulse heights were telemetered along with event data allowing us to conduct detailed studies of shield rejection effects. Preliminary results have been presented on the effectiveness of shielding and background reduction techniques that employ the DOI, as indicated by the ratio of cathode to anode pulse height (Slavis, et. al., SPIE Proc., 3445, 169, 1998, and Slavis, et. al., AAS #193, #66.05, 1999). Preliminary analysis indicates the 40-80 keV background is 4x10(-4) (cts)/(cm(2-s-keV)) for the cross-strip CZT without applying rejection techniques other than an active-shield energy deposition veto. We present here results incorporating more sophisticated background rejection techniques such as refinements to the preliminary DOI cut, multiple-site signatures and a more detailed investigation of the dependence of shield energy deposition on background rejection. We will also present upper limits on CZT activation. This is possible because the long duration at float in 1998 permitted cycling through the shield configurations for run times separated by at least 8 hours. Based on our preliminary analysis, we are confident that CZT detectors will be desirable for future low background, hard X-ray astronomy missions.

  7. Development of a fast position-sensitive laser beam detector

    SciTech Connect

    Chavez, Isaac; Huang Rongxin; Henderson, Kevin; Florin, Ernst-Ludwig; Raizen, Mark G.

    2008-10-15

    We report the development of a fast position-sensitive laser beam detector. The detector uses a fiber-optic bundle that spatially splits the incident beam, followed by a fast balanced photodetector. The detector is applied to the study of Brownian motion of particles on fast time scales with 1 A spatial resolution. Future applications include the study of molecule motors, protein folding, as well as cellular processes.

  8. Position-sensitive CZT detector module

    NASA Astrophysics Data System (ADS)

    Matteson, James L.; Duttweiler, Fred; Huszar, George L.; Leblanc, Philippe C.; Skelton, Robert E.; Stephan, Edwin A.; Hink, Paul L.; Dowkontt, Paul F.; Slavis, Kimberly R.; Tumer, Tumay O.; Kravis, Scott D.

    1998-07-01

    Coded mask imagers for future high energy x-ray astronomy missions will require detector planes with areas of hundreds to thousands of cm(superscript 2) and position resolutions < 1 mm. Such detectors will enable coded mask imagers to discover and study thousands of high energy x-ray sources. The UCSD/WU/UCR/NOVA collaboration has been developing CZT detector systems with crossed-strip readout to meet these requirements. We report progress on a compact detector module with 41 cm(superscript 2) area and 0.5 mm spatial resolution. The design includes the bias network and ASIC readout electronics, and allows modules to be combined in large area arrays with very high live-area factors. Results from laboratory and balloon flight tests are presented.

  9. Position sensitive detector for fluorescence lifetime imaging

    NASA Astrophysics Data System (ADS)

    Prokazov, Y.; Turbin, E.; Weber, A.; Hartig, R.; Zuschratter, W.

    2014-12-01

    We present a detector system with a microchannel plate based photomultiplier tube (MCP-PMT) and its application for fluorescence lifetime imaging (FLIM) in visible light. A capacity coupled imaging technique (charge image) combined with a charge division anode is employed for the positional readout. Using an artificial neural network's (ANN) computation model we are able to reconstruct the position of the incident photon as precise as 20 microns over the detector active area of 25 mm diameter. Thus, the resulting image quality corresponds roughly to a megapixel conventional CCD camera. Importantly, it is feasible to reach such resolution using only 9 charge acquisition channels supporting the anode structure of 14 interconnected readout electrodes. Additionally, the system features better than 50 ps temporal resolution allowing single photon counting FLIM acquisition with a regular fluorescence wide-field microscope.

  10. Neutron position-sensitive scintillation detector

    DOEpatents

    Strauss, Michael G.; Brenner, Raul

    1984-01-01

    A device is provided for mapping one- and two-dimensional distributions of neutron-positions in a scintillation detector. The device consists of a lithium glass scintillator coupled by an air gap and a light coupler to an array of photomultipliers. The air gap concentrates light flashes from the scintillator, whereas the light coupler disperses this concentrated light to a predetermined fraction of the photomultiplier tube array.

  11. Position sensitivity of MAMA detectors. [Multi-Anode Microchannel Array

    NASA Technical Reports Server (NTRS)

    Morgan, J. S.; Slater, D. S.; Timothy, J. G.; Jenkins, E. B.

    1988-01-01

    The results of laboratory and telescopic measurements of the position sensitivity of a visible MAMA detector utilizing a 'coarse-fine' array are presented. The photometric accuracy of this detector was determined under point source illumination. It was found that computed centroid positions are accurate across the entire array to within 0.04 pixels.

  12. Position sensitivity of MAMA detectors. [Multi-Anode Microchannel Array

    NASA Technical Reports Server (NTRS)

    Morgan, J. S.; Slater, D. S.; Timothy, J. G.; Jenkins, E. B.

    1988-01-01

    The results of laboratory and telescopic measurements of the position sensitivity of a visible MAMA detector utilizing a 'coarse-fine' array are presented. The photometric accuracy of this detector was determined under point source illumination. It was found that computed centroid positions are accurate across the entire array to within 0.04 pixels.

  13. Silicon position sensitive detectors for the HELIOS (NA34) experiment

    SciTech Connect

    Beuttenmuller, R.; Bisi, V.; Chesi, E.; Di Nardo, R.P.; Esten, M.J.; Giubellino, P.; Kraner, H.W.; Ludlam, T.W.; Meddi, F.; Piuz, F.

    1986-03-01

    Silicon detectors having both ''pad'' and strip position sensitive configurations have been fabricated for the HELIOS experiment which requires an elaborate pulse height-dependent trigger as well as one dimensional silicon strip position sensing. The trigger detector is a 400 element, 30 mm diameter detector with readout connections from a ceramic overlay board. Tests with full prototype detectors have shown essentially 100% detection efficiency and excellent pulse height resolution well capable of delineating 0, 1 or 2 hits per pad. Strip detectors with 25 ..mu..m pitch and a varying readout pitch have been tested, which utilize both capacitive and resistive charge division. Techniques for realization of required interstrip resistors will be discussed and results which may compare these readout methods will be reported. 11 refs., 13 figs.

  14. Self-Balancing Position-Sensitive Detector (SBPSD).

    PubMed

    Porrazzo, Ryan; Lydecker, Leigh; Gattu, Suhasini; Bakhru, Hassaram; Tokranova, Natalya; Castracane, James

    2015-07-20

    Optical position-sensitive detectors (PSDs) are a non-contact method of tracking the location of a light spot. Silicon-based versions of such sensors are fabricated with standard CMOS technology, are inexpensive and provide a real-time, analog signal output corresponding to the position of the light spot. An innovative type of optical position sensor was developed using two back-to-back connected photodiodes. These so called self-balancing position-sensitive detectors (SBPSDs) eliminate the need for external readout circuitry entirely. Fabricated prototype devices demonstrate linear, symmetric coordinate characteristics and a spatial resolution of 200 μm for a 74 mm device. PSDs are commercially available only up to a length of 37 mm. Prototype devices were fabricated with various lengths up to 100 mm and can be scaled down to any size below that.

  15. A high count rate one-dimensional position sensitive detector and a data acquisition system for time resolved X-ray scattering studies

    NASA Astrophysics Data System (ADS)

    Pernot, P.; Kahn, R.; Fourme, R.; Leboucher, P.; Million, G.; Santiard, J. C.; Charpak, G.

    1982-10-01

    A curved multiwire proportional drift chamber has been built as a general purpose instrument for X-ray scattering and X-ray diffraction experiments with synchrotron radiation. This parallax-free one-dimensional linear position sensitive detector has a parallel readout with a double hit logic. The data acquisition system, installed as a part of the D11 camera at LURE-DCI, is designed to perform time slicing and cyclic experiments; it has been used with either the fast multiwire chamber or a standard position sensitive detector with delay line readout.

  16. A position sensitive phoswich hard X-ray detector system

    NASA Technical Reports Server (NTRS)

    Dean, A. J.; Hanson, C. G.; Hopkins, C. J.; Lewis, R. A.; Fraser-Mitchell, J.

    1985-01-01

    A prototype position sensitive phoswich hard X-ray detector, designed for eventual astronomical usage, was tested in the laboratory. The scintillation crystal geometry was designed on the basis of a Monte Carlo simulation of the internal optics and includes a 3mm thick NaI(T1) primary X-ray detector which is actively shielded by a 20 mm thick CsI(T1) scintillation crystal. This phoswich arrangement is viewed by a number two inch photomultipliers. Measured values of the positional and spectral resolution of incident X-ray photons are compared with calculation.

  17. Spectroscopy of Actinide Nuclei - Perspectives with Position Sensitive HPGe Detectors

    NASA Astrophysics Data System (ADS)

    Reiter, P.; Birkenbach, B.; Kotthaus, T.

    Recent advances in in-beam gamma-ray spectroscopy of actinide nuclei are based on highly efficient arrays of escape-suppressed spectrometers. The sensitivity of these detector arrays is greatly enhanced by the combination with powerful mass separators or particle detector systems. This technique is demonstrated by an experiment to investigate excited states in 234U after the one-neutron-transfer reaction 235U(d,t). In coincidence with the outgoing tritons, γ-rays were detected with the highly efficient MINIBALL spectrometer. In the near future an even enhanced sensitivity will be achieved by utilizing position sensitive HPGe detectors which will exploit the novel detection method of gamma-ray energy tracking in electrically segmented germanium detectors. An example for this novel approach is the investigation neutron-rich actinide Th and U nuclei after multi nucleon transfer reactions employing the AGATA demonstrator and PRISMA setup at LNL, Italy. A primary 136Xe beam hitting a 238U target was used to produce the nuclei of interest. Beam-like reaction products after neutron transfer were selected by the PRISMA spectrometer. Coincident γ-rays from excited states in beam and target like particles were measured with the position sensitive AGATA HPGe detectors. Improved Doppler correction and quality of the γ-spectra is based on the novel γ-ray tracking technique, which was successfully exploited in this region.

  18. Emulation workbench for position sensitive gaseous scintillation detectors

    NASA Astrophysics Data System (ADS)

    Pereira, L.; Margato, L. M. S.; Morozov, A.; Solovov, V.; Fraga, F. A. F.

    2015-12-01

    Position sensitive detectors based on gaseous scintillation proportional counters with Anger-type readout are being used in several research areas such as neutron detection, search for dark matter and neutrinoless double beta decay. Design and optimization of such detectors are complex and time consuming tasks. Simulations, while being a powerful tool, strongly depend on the light transfer models and demand accurate knowledge of many parameters, which are often not available. Here we describe an alternative approach based on the experimental evaluation of a detector using an isotropic point-like light source with precisely controllable light emission properties, installed on a 3D positioning system. The results obtained with the developed setup at validation conditions, when the scattered light is strongly suppressed show good agreement with simulations.

  19. Position-Sensitive Nuclear Spectroscopy with Pixel Detectors

    SciTech Connect

    Granja, Carlos; Vykydal, Zdenek; Jakubek, Jan; Pospisil, Stanislav

    2007-10-26

    State-of-the-art hybrid semiconductor pixel detectors such as Medipix2 are suitable for energy- and position-sensitive nuclear spectroscopy. In addition to excellent energy- and spatial-resolution, these devices can operate in spectroscopic, single-quantum counting and/or on-line tracking mode. A devoted compact USB-readout interface provides functionality and ease of operation. The compact and versatile Medipix2/USB radiation camera provides visualization, vacuum and room-temperature operation as a real-time portable active nuclear emulsion.

  20. Position Sensitive Proximity Charge Sensing Readout of HPGe Detectors

    NASA Astrophysics Data System (ADS)

    Priest, Anders Peterson

    Electrode segmentation is a necessity to achieve position sensitivity in semicon- ductor radiation detectors. Traditional segmentation requires decreasing electrode sizes while increasing channel numbers to achieve very fine position resolution. These electrodes can be complicated to fabricate, and many electrodes with individual electronic channels are required to instrument large detector areas. To simplify the fabrication process, we have moved the readout electrodes onto a printed circuit board that is positioned above the ionization type detection material. In this scheme, charge from radiation interactions will be shared amongst several electrodes, allowing for position interpolation. Because events can be reconstructed in between electrodes, fewer electrodes are needed to instrument large detector areas. The proximity charge sensing method of readout promises to simplify detector fabrication while maintaining the position resolution that is required by fields such as homeland security, astrophysics, environmental remediation, nuclear physics, and medical imaging. We performed scanning measurements on a proof of principle detector that we fabricated at Lawrence Berkeley National Laboratory (LBNL). These measurements showed that position resolution much finer than the strip pitch was achievable using the proximity charge readout method. We performed analytic calculations and Monte Carlo modeling to optimize the readout electrode geometry for a larger detector to test the limits of this technology. We achieved an average position resolution of 288 microm with eight proximity electrodes at a 5 mm pitch and 1 mm strip width, set 100 microm away from the detector surface by a Kapton spacer. To achieve this resolution using standard technologies, 300 microm pitch strips are necessary, and would require 100 channels to instrument the same area. Through our optimization calculations, we found that there is a trade-off between position resolution and energy resolution

  1. READOUT ASIC FOR 3D POSITION-SENSITIVE DETECTORS.

    SciTech Connect

    DE GERONIMO,G.; VERNON, E.; ACKLEY, K.; DRAGONE, A.; FRIED, J.; OCONNOR, P.; HE, Z.; HERMAN, C.; ZHANG, F.

    2007-10-27

    We describe an application specific integrated circuit (ASIC) for 3D position-sensitive detectors. It was optimized for pixelated CZT sensors, and it measures, corresponding to an ionizing event, the energy and timing of signals from 121 anodes and one cathode. Each channel provides low-noise charge amplification, high-order shaping, along with peak- and timing-detection. The cathode's timing can be measured in three different ways: the first is based on multiple thresholds on the charge amplifier's voltage output; the second uses the threshold crossing of a fast-shaped signal; and the third measures the peak amplitude and timing from a bipolar shaper. With its power of 2 mW per channel the ASIC measures, on a CZT sensor Connected and biased, charges up to 100 fC with an electronic resolution better than 200 e{sup -} rms. Our preliminary spectral measurements applying a simple cathode/mode ratio correction demonstrated a single-pixel resolution of 4.8 keV (0.72 %) at 662 keV, with the electronics and leakage current contributing in total with 2.1 keV.

  2. ASIC for High Rate 3D Position Sensitive Detectors

    SciTech Connect

    Vernon, E.; De Geronimo, G.; Ackley, K.; Fried, J.; He, Z.; Herman, C.; Zhang, F.

    2010-06-16

    We report on the development of an application specific integrated circuit (ASIC) for 3D position sensitive detectors (3D PSD). The ASIC is designed to operate with pixelated wide bandgap sensors like Cadmium-Zinc-Telluride (CZT), Mercuric Iodide (Hgl2) and Thallium Bromide (TIBr). It measures the amplitudes and timings associated with an ionizing event on 128 anodes, the anode grid, and the cathode. Each channel provides low-noise charge amplification, high-order shaping with peaking time adjustable from 250 ns to 12 {micro}s, gain adjustable to 20 mV/fC or 120 mV/fC (for a dynamic range of 3.2 MeV and 530 keV in CZT), amplitude discrimination with 5-bit trimming, and positive and negative peak and timing detections. The readout can be full or sparse, based on a flag and single- or multi-cycle token passing. All channels, triggered channels only, or triggered with neighbors can be read out thus increasing the rate capability of the system to more than 10 kcps. The ASIC dissipates 330 mW which corresponds to about 2.5 mW per channel.

  3. Powder diffraction by fixed incident angle reflection using a curved position-sensitive detector

    SciTech Connect

    Haggerty, Ryan P.; Sarin, Pankaj; Bérar, Jean-Francois; Apostolov, Zlatomir D.; Kriven, Waltraud M.

    2010-05-25

    As curved position-sensitive detectors improve in angular resolution, the effects that fixed incident angle reflection have on X-ray diffraction peaks become more apparent. In this study the effects of sample transparency, incident beam height, detector resolution and sample displacement on the intensity, location, width and shape of powder diffraction peaks were examined. The functions describing each of these phenomena are presented and were successfully used to quantitatively model the diffraction peaks collected in this geometry. Three distinct regimes of diffraction peak resolution were identified from the phenomena that limit the peak variance. Pertinent criteria based on experimental parameters have been outlined to classify fixed incident angle reflection experiments into each regime. Guidelines for improvement of experimental resolution and for conducting analysis of data acquired using fixed incident angle reflection geometry and curved position-sensitive detectors are also provided.

  4. A position sensitive detector for EUV remote sensing

    NASA Technical Reports Server (NTRS)

    Siegmund, O. H. W.; Chakrabarti, S.; Cotton, D. M.; Lampton, M.

    1989-01-01

    The authors describe a photon-counting extreme ultraviolet (EUV) detector system used in a rocket-borne spectroscopic instrument for remote sensing of upper atmospheric composition and temperature. The detector uses a KBr coated microchannel plate (MCP) Z stack in combination with a wedge-and-strip image readout system. Three separate detector fields of view are used to sense the Earth dayglow spectrum (980 A to 1040 A, and 1300 A to 1360 A) and the solar EUV spectrum (250 A to 1400 A). The authors demonstrate high gain (2 x 107), tight pulse-height distribution (35 percent FWHM), and a spatial resolution of about 35 microns FWHM (full width at half maximum), which is the highest resolution for a wedge-and-strip anode MCP detector flown to date. The background, image linearity, and flat-field performance are discussed. Raw spectra from the rocket flight are also presented.

  5. DETECTORS AND EXPERIMENTAL METHODS: New test and analysis of position-sensitive-silicon-detector

    NASA Astrophysics Data System (ADS)

    Feng, Lang; Ge, Yu-Cheng; Wang, He; Fan, Feng-Ying; Qiao, Rui; Lu, Fei; Song, Yu-Shou; Zheng, Tao; Ye, Yan-Lin

    2009-01-01

    We have tested and analyzed the properties of two-dimensional Position-Sensitive-silicon-Detector (PSD) with new integrated preamplifiers. The test demonstrates that the best position resolution for 5.5 MeV α particles is 1.7 mm (FWHM), and the best energy resolution is 2.1%, which are notably better than the previously reported results. A scaling formula is introduced to make the absolute position calibration.

  6. PICsIT: a position sensitive detector for space applications

    NASA Astrophysics Data System (ADS)

    Labanti, C.; Di Cocco, G.; Malaguti, G.; Stephen, J. B.; Rossi, E.; Schiavone, F.; Traci, A.; Ferro, G.; Ferriani, S.; Mauri, A.; Visparelli, D.

    2002-01-01

    Pixellated Imaging CsI Telescope (PICsIT) is the high energy detector plane of Imager on Board INTEGRAL Satellite (IBIS), one of the main instruments on board the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite that will be launched in the year 2001. It consists of 4096 CsI(Tl) individual detector elements and operates in the energy range from 120 to 10,000keV. PICsIT is made up of 8 identical modules, each housing 512 scintillating crystals coupled to PIN photodiodes (PD). Each crystal, 30mm long and with a cross-section of 8.55×8.55mm2, is wrapped with a white diffusing coating and then inserted into an aluminium crate. In order to have a compact design, two electronic boards, mounted directly below the crystal/PD assembly, host both the Analogue and Digital Front-End Electronics (FEE). The behaviour of the read-out FEE has a direct impact on the performance of the whole detector in terms of lower energy threshold, energy resolution and event time tagging. Due to the great number of channels to be handled, an Application Specific Integrated Circuit (ASIC), that manages signals coming from groups of 16 detecting units, has been designed. The first reduced model of a PICsIT module has been now constructed and is under intensive tests in order to evaluate the main qualification parameters of the detector. In this paper, after a description of the PICsIT hardware and assembly procedures, the main results on system functionality are presented.

  7. Position sensitive and energy dispersive x-ray detector based on silicon strip detector technology

    NASA Astrophysics Data System (ADS)

    Wiącek, P.; Dąbrowski, W.; Fink, J.; Fiutowski, T.; Krane, H.-G.; Loyer, F.; Schwamberger, A.; Świentek, K.; Venanzi, C.

    2015-04-01

    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.

  8. Development of Position-sensitive Transition-edge Sensor X-ray Detectors

    NASA Technical Reports Server (NTRS)

    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.; hide

    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.

  9. Development of Position-sensitive Transition-edge Sensor X-ray Detectors

    NASA Technical Reports Server (NTRS)

    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.

  10. 3D scanning characteristics of an amorphous silicon position sensitive detector array system.

    PubMed

    Contreras, Javier; Gomes, Luis; Filonovich, Sergej; Correia, Nuno; Fortunato, Elvira; Martins, Rodrigo; Ferreira, Isabel

    2012-02-13

    The 3D scanning electro-optical characteristics of a data acquisition prototype system integrating a 32 linear array of 1D amorphous silicon position sensitive detectors (PSD) were analyzed. The system was mounted on a platform for imaging 3D objects using the triangulation principle with a sheet-of-light laser. New obtained results reveal a minimum possible gap or simulated defect detection of approximately 350 μm. Furthermore, a first study of the angle for 3D scanning was also performed, allowing for a broad range of angles to be used in the process. The relationship between the scanning angle of the incident light onto the object and the image displacement distance on the sensor was determined for the first time in this system setup. Rendering of 3D object profiles was performed at a significantly higher number of frames than in the past and was possible for an incident light angle range of 15 ° to 85 °.

  11. Time of flight elastic recoil detection analysis with a position sensitive detector

    SciTech Connect

    Siketic, Zdravko; Radovic, Iva Bogdanovic; Jaksic, Milko; Skukan, Natko

    2010-03-15

    A position sensitive detection system based on the microchannel plate detector has been constructed and installed at the existing time of flight (TOF) spectrometer in order to perform a kinematic correction and improve the surface time/depth resolution of elastic recoil detection analysis (ERDA) system. The position resolution of the detector has been tested for different types of ions and anode voltages. TOF spectra of recoiled O ions from SiO{sub 2} and F from CaF{sub 2} were collected in coincidence with position sensitive detector signal. Kinematic correction of TOF spectra improved surface time/depth resolution by {approx}20% for our system; however even higher improvements could be obtained in larger solid angle TOF-ERDA systems.

  12. CdZnTe position-sensitive drift detectors with thicknesses up to 5 cm

    NASA Astrophysics Data System (ADS)

    Bolotnikov, A. E.; Camarda, G. S.; Chen, E.; Cheng, S.; Cui, Y.; Gul, R.; Gallagher, R.; Dedic, V.; De Geronimo, G.; Ocampo Giraldo, L.; Fried, J.; Hossain, A.; MacKenzie, J. M.; Sellin, P.; Taherion, S.; Vernon, E.; Yang, G.; El-hanany, U.; James, R. B.

    2016-02-01

    We investigated the feasibility of long-drift-time CdZnTe (CZT) gamma-ray detectors, fabricated from CZT material produced by Redlen Technologies. CZT crystals with cross-section areas of 5 × 5 mm2 and 6 × 6 mm2 and thicknesses of 20-, 30-, 40-, and 50-mm were configured as 3D position-sensitive drift detectors and were read out using a front-end ASIC. By correcting the electron charge losses caused by defects in the crystals, we demonstrated high performance for relatively thick detectors fabricated from unselected CZT material.

  13. Position-sensitive CdTe detector using improved crystal growth method

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The feasibility of developing a position-sensitive CdTe detector array for astronomical observations in the hard X-ray, soft gamma ray region is demonstrated. In principle, it was possible to improve the resolution capability for imaging measurements in this region by orders of magnitude over what is now possible through the use of CdTe detector arrays. The objective was to show that CdTe crystals of the quality, size and uniformity required for this application can be obtained with a new high pressure growth technique. The approach was to fabricate, characterize and analyze a 100 element square array and several single-element detectors using crystals from the new growth process. Results show that detectors fabricated from transversely sliced, 7 cm diameter wafers of CdTe exhibit efficient counting capability and a high degree of uniformity over their entire areas. A 100 element square array of 1 sq mm detectors was fabricated and operated.

  14. Position sensitive x-ray spectrophotometer using microwave kinetic inductance detectors

    SciTech Connect

    Mazin, Benjamin A.; Bumble, Bruce; Day, Peter K.; Eckart, Megan E.; Golwala, Sunil; Zmuidzinas, Jonas; Harrison, Fiona A.

    2006-11-27

    The surface impedance of a superconductor changes when energy is absorbed and Cooper pairs are broken to produce single electron (quasiparticle) excitations. This change may be sensitively measured using a thin-film resonant circuit called a microwave kinetic inductance detector (MKID). The practical application of MKIDs for photon detection requires a method of efficiently coupling the photon energy to the MKID. The authors present results on position sensitive x-ray detectors made by using two aluminum MKIDs on either side of a tantalum photon absorber strip. Diffusion constants, recombination times, and energy resolution are reported. MKIDs can easily be scaled into large arrays.

  15. Initial characterization of a position-sensitive photodiode/BGO detector for PET (positron emission tomography)

    SciTech Connect

    Derenzo, S.E.; Moses, W.W.; Jackson, H.G.; Turko, B.T.; Cahoon, J.L.; Geyer, A.B.; Vuletich, T.

    1988-11-01

    We present initial results of a position-sensitive photodiode/BGO detector for high resolution, multi-layer positron emission tomography (PET). Position sensitivity is achieved by dividing the 3 mm /times/ 20 mm rectangular photosensitive area along the diagonal to form two triangular segments. Each segment was individually connected to a low-noise amplifier. The photodiodes and crystals were cooled to /minus/100/degree/C to reduce dark current and increase the BGO signal. With an amplifier peaking time of 17 ..mu..sec, the sum of the signals (511 keV photopeak) was 3200 electrons with a full width at half maximum (fwhm) of 750 electrons. The ratio of one signal to the sum determined the depth of interaction with a resolution of 11 mm fwhm. 27 refs., 7 figs.

  16. Exploring the spatial resolution of position-sensitive microchannel plate detectors

    NASA Astrophysics Data System (ADS)

    Wiggins, Blake; Siwal, Davinder; Desouza, Romualdo

    2016-03-01

    High amplification and excellent timing make microchannel plate (MCP) detectors excellent devices for detection of photons, electrons, and ions. In addition to providing sub-nanosecond time resolution MCP detectors can also provide spatial resolution, thus making them useful in imaging applications. Use of a resistive anode (RA) is a routinely used approach to make an MCP position-sensitive. The spatial resolution of the RA associated with detection of a single incident electron was determined. Factors impacting the spatial resolution obtained with the RA will be discussed and the achieved spatial resolution of 64 μm (FWHM) will be presented. Recently, a novel approach has been developed to provide position-sensitivity for an MCP detector. In this approach, namely the induced signal approach, the position of the incident particle is determined by sensing the electron cloud emanating from a MCP stack. By utilizing the zero-crossing point of the inherently bipolar signals, a spatial resolution of 466 μm (FWHM) has been achieved. Work to improve the spatial resolution of the induced signal approach further will be presented. Supported by the US DOE NNSA under Award No. DE-NA0002012.

  17. Compton imaging with a highly-segmented, position-sensitive HPGe detector

    NASA Astrophysics Data System (ADS)

    Steinbach, T.; Hirsch, R.; Reiter, P.; Birkenbach, B.; Bruyneel, B.; Eberth, J.; Gernhäuser, R.; Hess, H.; Lewandowski, L.; Maier, L.; Schlarb, M.; Weiler, B.; Winkel, M.

    2017-02-01

    A Compton camera based on a highly-segmented high-purity germanium (HPGe) detector and a double-sided silicon-strip detector (DSSD) was developed, tested, and put into operation; the origin of γ radiation was determined successfully. The Compton camera is operated in two different modes. Coincidences from Compton-scattered γ-ray events between DSSD and HPGe detector allow for best angular resolution; while the high-efficiency mode takes advantage of the position sensitivity of the highly-segmented HPGe detector. In this mode the setup is sensitive to the whole 4π solid angle. The interaction-point positions in the 36-fold segmented large-volume HPGe detector are determined by pulse-shape analysis (PSA) of all HPGe detector signals. Imaging algorithms were developed for each mode and successfully implemented. The angular resolution sensitively depends on parameters such as geometry, selected multiplicity and interaction-point distances. Best results were obtained taking into account the crosstalk properties, the time alignment of the signals and the distance metric for the PSA for both operation modes. An angular resolution between 13.8° and 19.1°, depending on the minimal interaction-point distance for the high-efficiency mode at an energy of 1275 keV, was achieved. In the coincidence mode, an increased angular resolution of 4.6° was determined for the same γ-ray energy.

  18. Position-sensitive ``movie'' in situ neutron detector for the UCN τ experiment

    NASA Astrophysics Data System (ADS)

    Weaver, Hannah; UCNTau Collaboration

    2016-09-01

    Precision measurements of neutron β-decay parameters provide tests of fundamental theories in elementary particle physics and cosmology such as the Standard Model and Big Bang nucleosynthesis. In particular, the UCN τ experiment aims to measure the mean lifetime of ultracold neutrons confined in an asymmetric magneto-gravitational trap using an in situ neutron detector. This detector consists of a 20 nm film of 10B on top of a ZnS:Ag scintillating screen. The screen is readout using two photomultipliers which view an array of wavelength shifting fibers optically coupled to the scintillator. When the detector is lowered into the loaded trap, light is emitted due to the charged particles recoiling into the ZnS:Ag when neutrons absorb on the 10B. Phase space evolution in the stored neutron population can lead to apparent shifts in the measured neutron lifetime with the detector height. In order to quantify this systematic uncertainty, we are implementing a supplemental 64-channel position-sensitive PMT module with high quantum efficiency and fast time response to image the entire detector in situ during measurements. We have characterized a prototype using a ZnS screen and an α-particle source along with a prototype lens system and will report the results and future plans.

  19. An improved method of energy calibration for position-sensitive silicon detectors

    NASA Astrophysics Data System (ADS)

    Sun, Ming-Dao; Huang, Tian-Heng; Liu, Zhong; Ding, Bing; Yang, Hua-Bin; Zhang, Zhi-Yuan; Wang, Jian-Guo; Ma, Long; Yu, Lin; Wang, Yong-Sheng; Gan, Zai-Guo; Xiao-Hong, Zhou

    2016-04-01

    Energy calibration of resistive charge division-based position-sensitive silicon detectors is achieved by parabolic fitting in the traditional method, where the systematic variations of vertex and curvature of the parabola with energy must be considered. In this paper we extend the traditional method in order to correct the fitting function, simplify the procedure of calibration and improve the experimental data quality. Instead of a parabolic function as used in the traditional method, a new function describing the relation of position and energy is introduced. The energy resolution of the 8.088 MeV α decay of 213Rn is determined to be about 87 keV (FWHM), which is better than the result of the traditional method, 104 keV (FWHM). The improved method can be applied to the energy calibration of resistive charge division-based position-sensitive silicon detectors with various performances. Supported by ‘100 Person Project’ of the Chinese Academy of Sciences and the National Natural Science Foundation of China (11405224 and 11435014)

  20. Fourier synthesis image reconstruction by use of one-dimensional position-sensitive detectors.

    PubMed

    Kotoku, Jun'ichi; Makishima, Kazuo; Okada, Yuu; Negoro, Hitoshi; Terada, Yukikatsu; Kaneda, Hidehiro; Oda, Minoru

    2003-07-10

    An improvement of Fourier synthesis optics for hard x-ray imaging is described, and the basic performance of the new optics is confirmed through numerical simulations. The original concept of the Fourier synthesis imager utilizes nonposition-sensitive hard x-ray detectors coupled to individual bigrid modulation collimators. The improved concept employs a one-dimensional position-sensitive detector (such as a CdTe strip detector) instead of the second grid layer of each bigrid modulation collimator. This improves the imaging performance in several respects over the original design. One performance improvement is a two-fold increase in the average transmission, from 1/4 to 1/2. The second merit is that both the sine and cosine components can be derived from a single grid-detector module, and hence the number of imaging modules can be halved. Furthermore, it provides information along the depth direction simultaneously. This in turn enables a three-dimensional imaging hard x-ray microscope for medical diagnostics, incorporating radioactive tracers. A conceptual design of such a microscope is presented, designed to provide a field of view of 4 mm and a spatial resolution of 400 microm.

  1. A multiplexed TOF and DOI capable PET detector using a binary position sensitive network

    NASA Astrophysics Data System (ADS)

    Bieniosek, M. F.; Cates, J. W.; Levin, C. S.

    2016-11-01

    Time of flight (TOF) and depth of interaction (DOI) capabilities can significantly enhance the quality and uniformity of positron emission tomography (PET) images. Many proposed TOF/DOI PET detectors require complex readout systems using additional photosensors, active cooling, or waveform sampling. This work describes a high performance, low complexity, room temperature TOF/DOI PET module. The module uses multiplexed timing channels to significantly reduce the electronic readout complexity of the PET detector while maintaining excellent timing, energy, and position resolution. DOI was determined using a two layer light sharing scintillation crystal array with a novel binary position sensitive network. A 20 mm effective thickness LYSO crystal array with four 3 mm  ×  3 mm silicon photomultipliers (SiPM) read out by a single timing channel, one energy channel and two position channels achieved a full width half maximum (FWHM) coincidence time resolution of 180  ±  2 ps with 10 mm of DOI resolution and 11% energy resolution. With sixteen 3 mm  ×  3 mm SiPMs read out by a single timing channel, one energy channel and four position channels a coincidence time resolution 204  ±  1 ps was achieved with 10 mm of DOI resolution and 15% energy resolution. The methods presented here could significantly simplify the construction of high performance TOF/DOI PET detectors.

  2. A multiplexed TOF and DOI capable PET detector using a binary position sensitive network.

    PubMed

    Bieniosek, M F; Cates, J W; Levin, C S

    2016-11-07

    Time of flight (TOF) and depth of interaction (DOI) capabilities can significantly enhance the quality and uniformity of positron emission tomography (PET) images. Many proposed TOF/DOI PET detectors require complex readout systems using additional photosensors, active cooling, or waveform sampling. This work describes a high performance, low complexity, room temperature TOF/DOI PET module. The module uses multiplexed timing channels to significantly reduce the electronic readout complexity of the PET detector while maintaining excellent timing, energy, and position resolution. DOI was determined using a two layer light sharing scintillation crystal array with a novel binary position sensitive network. A 20 mm effective thickness LYSO crystal array with four 3 mm  ×  3 mm silicon photomultipliers (SiPM) read out by a single timing channel, one energy channel and two position channels achieved a full width half maximum (FWHM) coincidence time resolution of 180  ±  2 ps with 10 mm of DOI resolution and 11% energy resolution. With sixteen 3 mm  ×  3 mm SiPMs read out by a single timing channel, one energy channel and four position channels a coincidence time resolution 204  ±  1 ps was achieved with 10 mm of DOI resolution and 15% energy resolution. The methods presented here could significantly simplify the construction of high performance TOF/DOI PET detectors.

  3. Adhesion Force Measurements Using an Atomic Force Microscope Upgraded with a Linear Position Sensitive Detector

    PubMed Central

    Pierce, M.; Stuart, J.; Pungor, A.; Dryden, P.

    2012-01-01

    The atomic force microscope (AFM), in addition to providing images on an atomic scale, can be used to measure the forces between surfaces and the AFM probe. The potential uses of mapping the adhesive forces on the surface include a spatial determination of surface energy and a direct identification of surface proteins through specific protein–ligand binding interactions. The capabilities of the AFM to measure adhesive forces can be extended by replacing the four-quadrant photodiode detection sensor with an external linear position sensitive detector and by utilizing a dedicated user-programmable signal generator and acquisiton system. Such an upgrade enables the microscope to measure in the larger dynamic range of adhesion forces, improves the sensitivity and linearity of the measurement, and eliminates the problems inherent to the multiple repetitious contacts between the AFM probe and the specimen surface. PMID:25125792

  4. Experience with position-sensitive neutron detectors at the Intense Pulsed Neutron Source

    NASA Astrophysics Data System (ADS)

    Crawford, R. K.; Haumann, J. R.; Epperson, J. E.; Thiyagarajan, P.; Schultz, A. J.; Felcher, G. P.; Montague, D. G.; Dejus, R. J.

    1990-12-01

    At the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory, pulses of protons accelerated in a synchrotron produce pulses of fast neutrons via the spallation process in an enriched uranium target. After moderation, the resulting pulses of slow neutrons are directed into beams which serve a variety of neutron-scattering instruments. Currently there are thirteen neutron-scattering instruments in operation or under development at IPNS, and six of these use position-sensitive neutron detectors (PSDs). These PSDs are: a 30 cm × 30 cm, ˜3 mm resolution, neutron Anger camera area PSD with 6Li-glass scintillator; a 2.5 cm diameter, ˜0.7 mm resolution, microchannel-plate area PSD with 6Li-glass scintillator; a 20 cm × 20 cm, ˜5 mm resolution, 3He proportional-counter area PSD; a 40 cm × 40 cm, ˜4 mm resolution, 3He proportional-counter area PSD; a flat 20 cm long, ˜1.6 mm resolution, 3He proportional-counter linear PSD; and 160 cylindrical 3He proportional-counter linear PSDs, each of which is 1.27 cm in diameter and 60 cm long and has ˜14 mm resolution. These detectors, in addition to being position-sensitive, resolve the time of the neutron capture with ˜1 μs precision for neutron time-of-flight measurements. This paper will discuss these various PSDs with emphasis on the instrumental specifications and the reasons for the selection of the different types of PSDs, and will also discuss the observed performances of these PSDs.

  5. Experience with position sensitive neutron detectors at the Intense Pulsed Neutron Source

    SciTech Connect

    Crawford, R.K.; Haumann, J.R.; Schultz, A.J.; Felcher, G.P.; Epperson, J.E.; Thiyagarajan, P.; Montague, D.G.; Dejus, R.J.

    1990-05-07

    At the Intense Pulsed Neutron Source (IPNS) pulses of protons accelerated in a synchrotron produce pulses of fast neutrons via the spallation process in an enriched uranium target. After moderation, the resulting pulses of slow neutrons are directed into beams which serve a variety of neutron scattering instruments. Currently there are thirteen neutron scattering instruments in operation or under development at IPNS, and six of these use position-sensitive neutron detectors (PSDs). These PSDs are: a 30 cm {times} 30 cm, {approximately}3 mm resolution, neutron Anger camera area PSD with {sup 6}Li-glass scintillator; a 2.5 cm dia, {approximately}0.7 mm resolution, microchannel-plate area PSD with {sup 6}Li-glass scintillator; a 20 cm {times} 20 cm, {approximately}5 mm resolution, {sup 3}He proportional counter area PSD; a 40 cm {times} 40 cm, {approximately}4 mm resolution, {sup 3}He proportional counter area PSD; a flat 20 cm long, {approximately}1.6 mm resolution, {sup 3}He proportional counter linear PSD; and 160 cylindrical {sup 3}He proportional counter linear PSDs, each of which is 1.27 cm in dia 60 cm long and has {approximately}14 mm resolution. These detectors, in addition to being position-sensitive, resolve the time of the neutron capture with {approximately}1 {mu}s precision for neutron time-of-flight measurements. This paper will discuss these various PSDs with emphasis on the instrumental specifications and the reasons for the selection of the different types of PSDs, and will also discuss the observed performances of these PSDs. 14 refs., 6 figs., 1 tab.

  6. Development of a high-count-rate neutron detector with position sensitivity and high efficiency

    SciTech Connect

    Nelson, R.; Sandoval, J.

    1996-10-01

    While the neutron scattering community is bombarded with hints of new technologies that may deliver detectors with high-count-rate capability, high efficiency, gamma-ray insensitivity, and high resolution across large areas, only the time-tested, gas-filled {sup 3}He and scintillation detectors are in widespread use. Future spallation sources with higher fluxes simply must exploit some of the advanced detector schemes that are as yet unproved as production systems. Technologies indicating promise as neutron detectors include pixel arrays of amorphous silicon, silicon microstrips, microstrips with gas, and new scintillation materials. This project sought to study the competing neutron detector technologies and determine which or what combination will lead to a production detector system well suited for use at a high-intensity neutron scattering source.

  7. Depth of interaction resolution measurements for a high resolution PET detector using position sensitive avalanche photodiodes.

    PubMed

    Yang, Yongfeng; Dokhale, Purushottam A; Silverman, Robert W; Shah, Kanai S; McClish, Mickel A; Farrell, Richard; Entine, Gerald; Cherry, Simon R

    2006-05-07

    We explore dual-ended read out of LSO arrays with two position sensitive avalanche photodiodes (PSAPDs) as a high resolution, high efficiency depth-encoding detector for PET applications. Flood histograms, energy resolution and depth of interaction (DOI) resolution were measured for unpolished LSO arrays with individual crystal sizes of 1.0, 1.3 and 1.5 mm, and for a polished LSO array with 1.3 mm pixels. The thickness of the crystal arrays was 20 mm. Good flood histograms were obtained for all four arrays, and crystals in all four arrays can be clearly resolved. Although the amplitude of each PSAPD signal decreases as the interaction depth moves further from the PSAPD, the sum of the two PSAPD signals is essentially constant with irradiation depth for all four arrays. The energy resolutions were similar for all four arrays, ranging from 14.7% to 15.4%. A DOI resolution of 3-4 mm (including the width of the irradiation band which is approximately 2 mm) was obtained for all the unpolished arrays. The best DOI resolution was achieved with the unpolished 1 mm array (average 3.5 mm). The DOI resolution for the 1.3 mm and 1.5 mm unpolished arrays was 3.7 and 4.0 mm respectively. For the polished array, the DOI resolution was only 16.5 mm. Summing the DOI profiles across all crystals for the 1 mm array only degraded the DOI resolution from 3.5 mm to 3.9 mm, indicating that it may not be necessary to calibrate the DOI response separately for each crystal within an array. The DOI response of individual crystals in the array confirms this finding. These results provide a detailed characterization of the DOI response of these PSAPD-based PET detectors which will be important in the design and calibration of a PET scanner making use of this detector approach.

  8. 300-element silicon-lithium position-sensitive imaging detector for angiography

    SciTech Connect

    Walton, J.T.; Sommer, H.A.; Thompson, A.C.; Hughes, E.B.; Zeman, H.D.

    1985-10-01

    Silicon lithium-drifted (Si(Li)) detectors 150 mm long, 10 mm wide and 5 mm thick with 300 individual elements have been fabricated as imaging detectors for noninvasive studies of human coronary arteries using 33 keV x-rays from a synchrotron radiation beamline. This detector is an extension of earlier work on 30 mm long devices with initially 30 and later 60 elements. The detector fabrication details are discussed highlighting problems in uniform lithium-ion compensation. The device structure is examined and measurements on the interelement impedances presented. Finally an angiograph of the coronary arteries in an excised pig's heart obtained with this 300-element detector is presented. 14 refs., 6 figs.

  9. Force Control by Flexible Manipulator Based on Resonance Ratio Control using Position Sensitive Detector

    NASA Astrophysics Data System (ADS)

    Katsura, Seiichiro; Ohnishi, Kouhei

    This paper presents a novel force controller to suppress torsional vibration of two-mass resonant system. The resonance ratio control is one of the effective control methods of two-mass resonant system. In this method, the ratio between the resonant frequency of motor and arm is determined arbitrary according to the feedback of estimated reaction torque. The reaction torque is estimated by using position sensitive detector (PSD). Since the estimation method does not need the parameter identification, the torsion information is obtained with accuracy. To attain the affinity and adaptability to environment, motion systems should control the reaction force from the environment. In the force control system, the force response is regarded as a disturbance of the arm portion. The arm disturbance is observed by the arm disturbance observer. The proposed force control system is based on both the conventional PD control and the resonance ratio control and the determination method of pole placement is discussed. The proposed force control system can realize both the suppression of the inner torsional reaction torque and the adaptation to outer force inputs. The numerical and experimental results show viability of the proposed method.

  10. A position-sensitive neutron spectrometer/dosimeter based on pressurized superheated drop (bubble) detectors

    NASA Astrophysics Data System (ADS)

    d'Errico, F.; Nath, R.; Holland, S. K.; Lamba, M.; Patz, S.; Rivard, M. J.

    2002-01-01

    A position-sensitive, superheated emulsion chamber (SEC) is introduced for three-dimensional (3D) spectrometry and dosimetry of fast neutrons. The detector is based on a fine suspension of octafluorocyclobutane droplets emulsified in a tissue-equivalent gel. This gel is highly viscous and immobilizes the bubbles at the location of their formation. At an operating temperature of 35°C, the droplets are moderately superheated and their evaporation is nucleated by the densely ionizing products of fast neutron interactions, with no response to sparsely ionizing radiations. Thus, when a neutron emitter such as a 252Cf brachytherapy source is inserted in the SEC, a bubble distribution forms around the source and makes the neutron field visible. The SEC is operated at different externally applied pressures that correspond to different response thresholds. These responses form a virtually orthogonal matrix which is suitable for spectrometry and allows the use of effective few channel unfolding procedures, yielding the spatial dependence of absorbed dose and neutron energy spectra in-tissue. Bubble spatial distributions in the chamber can be determined through optical tomography or magnetic resonance imaging (MRI). A 3D, steady-state MRI method has proven particularly effective for this purpose. After the imaging, the SEC can be pressurized above the halocarbon vapor tension in order to recondense the bubbles to the liquid phase. Within a few minutes, the device is annealed and ready to be used again for repeated measurements improving the bubble counting statistics.

  11. High spatial resolution two-dimensional position sensitive detector for the performance of coincidence experiments

    SciTech Connect

    Ceolin, D.; Chaplier, G.; Lemonnier, M.; Garcia, G.A.; Miron, C.; Nahon, L.; Simon, M.; Leclercq, N.; Morin, P.

    2005-04-01

    A position sensitive detector (PSD) adapted to the technical and mechanical specifications of our angle and energy resolved electron-ion(s) coincidence experiments is described in this article. The device, whose principle is very similar to the one detailed by J. H. D. Eland [Meas. Sci. Technol. 5, 1501 (1994)], is composed by a set of microchannel plates and a delay line anode. The originality comes from the addition in front of the encoding surface of a ceramic disk covered by a resistive surface. The capacitive coupling between the anode and the resistive plane has the double advantage of eliminating the spatial modulations due to the lattice of the anode and also of sensitizing a greater number of electrodes, increasing thus considerably the accuracy of the position measurements. The tests carried out with a time to digital conversion module of 250 ps resolution showed that a spatial resolution better than 50 {mu}m and a dead time of 160 ns can be achieved. Typical images obtained with the help of the EPICEA and DELICIOUS coincidence setups are also shown.

  12. Improvement of the position linearity in a comb-type one-dimensional position sensitive detector

    NASA Astrophysics Data System (ADS)

    Tang, Jiuyao; Huang, Meizhen; Kim, Hoseob

    2002-09-01

    In a conventional, strip-type one-dimensional (1-D) position sensitive detector (PSD) the sensitive area and the position resistance area are combined together, the contact structure of the device is handicapped, so its accuracy and linearity is affected adversely. The sensitive area and the position resistance area in a new, comb-type 1-D PSD are separated to become the comb teeth and the comb ridge area respectively, moreover the position resistance area is made very narrow, thus the doping uniformity of that area is greatly improved. On the other hand, its position resistance can be largely increased owing to its narrower shape, if doping level is kept the same, so the restriction that is imposed on the contact structure previously can be lifted. Our measurements made on a strip-type 1-D PSD and a comb type 1-D PSD confirmed this difference, and showed that the accuracy and linearity of the comb type 1-D PSD has been increased markedly, especially the RMS nonlinearity of the comb type 1-D PSD is reduced to 0.090% from that of the strip-type 1-D PSD, 0.94%.

  13. Position sensitive photon detectors using epitaxial InGaAs/InAlAs quantum wells

    NASA Astrophysics Data System (ADS)

    Ganbold, T.; Antonelli, M.; Biasiol, G.; Cautero, G.; Jark, H.; Eichert, D. M.; Cucini, R.; Menk, R. H.

    2014-12-01

    This work deals with the investigation of novel position-sensitive devices based on InGaAs/InAlAs quantum wells, which could be applied to several applications of either synchrotron or conventional light sources. Such devices may be used as fast and efficient detectors due to the direct, low-energy band gap and high electron mobility at room temperature. Metamorphic In0.75Ga0.25As/In0.75Al0.25As quantum wells containing a two-dimensional electron gas were grown by molecular beam epitaxy. Two devices with size of 5 × 5 mm2 were prepared by using optical lithography. In the first, the active layers were segmented into four electrically insulated quadrants. Indium ohmic contacts were realized on the corner of each quadrant (for readout) and on the back surface (for bias). In the second, the quantum well was left unsegmented and covered by 400 nm of Al providing a single bias electrode, while four readout electrodes were fabricated on the back side by depositing and segmenting a Ni/Ge/Au layer. Photo-generated carriers can be collected at the readout electrodes by biasing from either the QW side or the back side of the devices during beam exposure. Individual currents obtained from each electrode allow monitoring of both the position and the intensity of the impinging beam for photon energies ranging from visible to hard X-ray. Such detector prototypes were tested with synchrotron radiation. Moreover, the position of the beam can be estimated with a precision of 800 nm in the segmented QW. A lower precision of 10 μm was recorded in the unsegmented QW due to the charge diffusion through the 500-μm-thick wafer, with however a lower electronic noise due to the better uniformity of the contacts.

  14. CdZnTe position-sensitive drift detectors with thicknesses up to 5 cm

    SciTech Connect

    Bolotnikov, A. E. Camarda, G. S.; Cui, Y.; Gul, R.; De Geronimo, G.; Fried, J.; Hossain, A.; Vernon, E.; Yang, G.; James, R. B.; Chen, E.; MacKenzie, J. M.; Taherion, S.; El-hanany, U.; Cheng, S.; Gallagher, R.; Dedic, V.; Ocampo Giraldo, L.; Sellin, P.

    2016-02-29

    We investigated the feasibility of long-drift-time CdZnTe (CZT) gamma-ray detectors, fabricated from CZT material produced by Redlen Technologies. CZT crystals with cross-section areas of 5 × 5 mm{sup 2} and 6 × 6 mm{sup 2} and thicknesses of 20-, 30-, 40-, and 50-mm were configured as 3D position-sensitive drift detectors and were read out using a front-end ASIC. By correcting the electron charge losses caused by defects in the crystals, we demonstrated high performance for relatively thick detectors fabricated from unselected CZT material.

  15. Comparison of various stopping gases for 3He-based position sensitive neutron detectors

    NASA Astrophysics Data System (ADS)

    Doumas, A.; Smith, G. C.

    2012-05-01

    A range of solid state, scintillator and gas based detectors are being developed for use at the next generation of high flux neutron facilities. Since gas detectors are expected to continue to play a key role in future specific thermal neutron experiments, a comparison of the performance characteristics of prospective stopping gases is beneficial. Gas detectors typically utilize the reaction 3He(n,p)t to detect thermal neutrons; the 3He gas is used in a mixture containing a particular stopping gas in order to maintain relatively short ranges for the proton and triton pair emitted from the n-3He reaction. Common stopping gases include hydrocarbons (e.g. propane), carbon tetrafluoride, and noble gases such as argon and xenon. For this study, we utilized the Monte Carlo simulation code "Stopping and Range of Ions in Matter" to analyze the expected behavior of argon, xenon, carbon dioxide, difluoroethane and octafluoropropane as stopping gases for thermal neutron detectors. We also compare these findings to our previously analyzed performance of propane, butane and carbon tetrafluoride. A discussion of these gases includes their behavior in terms of proton and triton range, ionization distribution and straggle.

  16. Complex microcalorimeter models and their application to position-sensitive detectors

    SciTech Connect

    Figueroa-Feliciano, Enectali

    2006-06-01

    We present a general formalism for calculating the linear response, noise spectrum, and energy resolution of complex calorimeters. Using this formalism calorimeters with arbitrary numbers of distinct linked heat capacity systems and/or coupled thermometers can be analyzed. We use this formalism to derive the theoretical resolution of an imaging microcalorimeter called a position- sensitive transition-edge sensor.

  17. New beam line for time-of-flight medium energy ion scattering with large area position sensitive detector

    NASA Astrophysics Data System (ADS)

    Linnarsson, M. K.; Hallén, A.; Åström, J.; Primetzhofer, D.; Legendre, S.; Possnert, G.

    2012-09-01

    A new beam line for medium energy ion mass scattering (MEIS) has been designed and set up at the Ångström laboratory, Uppsala University, Sweden. This MEIS system is based on a time-of-flight (ToF) concept and the electronics for beam chopping relies on a 4 MHz function generator. Repetition rates can be varied between 1 MHz and 63 kHz and pulse widths below 1 ns are typically obtained by including beam bunching. A 6-axis goniometer is used at the target station. Scattering angle and energy of backscattered ions are extracted from a time-resolved and position-sensitive detector. Examples of the performance are given for three kinds of probing ions, 1H+, 4He+, and 11B+. Depth resolution is in the nanometer range and 1 and 2 nm thick Pt layers can easily be resolved. Mass resolution between nearby isotopes can be obtained as illustrated by Ga isotopes in GaAs. Taking advantage of the large size detector, a direct imaging (blocking pattern) of crystal channels are shown for hexagonal, 4H-SiC. The ToF-MEIS system described in this paper is intended for use in semiconductor and thin film areas. For example, depth profiling in the sub nanometer range for device development of contacts and dielectric interfaces. In addition to applied projects, fundamental studies of stopping cross sections in this medium energy range will also be conducted.

  18. Advanced data readout technique for Multianode Position Sensitive Photomultiplier Tube applicable in radiation imaging detectors

    NASA Astrophysics Data System (ADS)

    Popov, V.

    2011-01-01

    Most of the best performing PSPMT tubes from Hamamatsu and Burle are designed with a pad-matrix anode layout. However, for obtaining a high resolution, a small-sized anode photomultiplier tubes are preferable; these tubes may have 64, 256 or 1024 anodes per tube. If the tubes are used in array to get a larger area detector, the number of analog channels may range from hundreds to thousands. Multichannel analog readout requires special electronics ICs, ASICs etc., which are attached to multichannel DAQ system. As a result, the data file and data processing time will be increased. Therefore, this readout could not be performed in a small project. Usually, most of radiation imaging applications allow the use of analog data processing in front-end electronics, significantly reducing the number of the detector's output lines to data acquisition without reducing the image quality. The idea of pad-matrix decoupling circuit with gain correction was invented and intensively tested in JLab. Several versions of PSPMT readout electronics were produced and studied. All developments were done and optimized specifically for radiation imaging projects. They covered high resolution SPECT, high speed PET, fast neutron imaging, and single tube and multi tube array systems. This paper presents and discusses the summary of the observed results in readout electronics evaluation with different PSPMTs and radiation imaging systems, as well as the advantages and limitations of the developed approach to radiation imaging detectors readout.

  19. Evaluation of a position sensitive neutron detector based on Li6Gd(BO3)3 scintillator

    NASA Astrophysics Data System (ADS)

    Schooneveld, Erik M.; Czirr, J. B.; McKnight, Thomas K.; Rhodes, Nigel J.; Ibberson, R. M.

    2002-11-01

    As a result of the ever increasing demand for higher neutron flux, future neutron scintillator detectors will require faster scintillators with a high light yield and low gamma sensitivity. Initial measurements with single element prototypes demonstrated that the new lithium gadolinium borate (LiGdBO) scintillator, using 6Li as the neutron absorber, was a promising candidate. As a result of this work, a full size position sensitive detector module has been made consisting of 120 LiGdBO elements. This module was installed on the High Resolution Powder Diffractometer (HRPD) beam line at ISIS for evaluation. The LiGdBO detector has been constructed with the same geometry and theoretically the same neutron absorption efficiency as the existing HRPD ZnS scintillator detector modules. In this way it was possible to make a more exact comparison of the relative detector performances. Measurements have shown that the neutron energy resolution and detection efficiency of both types of detector are identical. Gamma sensitivity and quiet count rate are somewhat higher for the LiGdBO than the ZnS scintillator detector, but still at an acceptable level for many applications. The short decay time of the LiGdBO scintillator has enhanced the count-rate capability of the detector by an order of magnitude. These measurements show that realistic large area position sensitive neutron detectors can be fabricated with LiGdBO scintillator using an optical fibre readout. LiGdBO is thus a promising scintillator for future detectors at the new high flux facilities currently under construction.

  20. A position-sensitive X-ray detector for the HEAO-A satellite.

    NASA Technical Reports Server (NTRS)

    Held, D.; Weisskopf, M. C.

    1973-01-01

    A position-sensitive, low-energy proportional counter system is described which will be used on the High-Energy Astronomical Observatory, Mission A, spacecraft. The associated system incorporates the capability to employ pulse-shape discrimination for background rejection and interpolation circuitry to locate the centroid of an X-ray event with an accuracy of approximately one eighth the cathode-wire spacing.

  1. Fast neutron spectrometry and dosimetry using a spherical moderator with position-sensitive detectors.

    PubMed

    Li, Taosheng; Yang, Lianzhen; Ma, Jizeng; Fang, Dong

    2007-01-01

    A neutron spectrometry and dosimetry measurement system has been developed based on a different design of the divided regions for a sphere, with three position-sensitive counters. The characteristics of the measurement system have been investigated in the reference radiation fields of Am-Be and (252)Cf sources. When realistic input spectra are used for the unfolding, the overall deviations of the calculated results for four dosimetric quantities are less than +/-10%. The results of other input spectra are also discussed in this report.

  2. Sealed position sensitive hard X-ray detector having large drift region for all sky camera with high angular resolution

    NASA Technical Reports Server (NTRS)

    Gorenstein, P.; Perlman, D.; Parsignault, D.; Burns, R.

    1979-01-01

    A sealed position sensitive proportional counter filled with two atmospheres of 95% xenon and 5% methane, and containing a drift region of 24 atm cm, has operated in a stable manner for many months. The detector contains G-10 frames to support the anode and cathode wires. The detector was sealed successfully by a combination of vacuum baking the G-10 frames at 150 C for two weeks followed by assembly into the detector in an environment of dry nitrogen, and the use of passive internal getters. The counter is intended for use with a circumferential cylindrical collimator. Together they provide a very broad field of view detection system with the ability to locate cosmic hard X-ray and soft gamma ray sources to an angular precision of a minute of arc. A set of instruments based on this principle have been proposed for satellites to detect and precisely locate cosmic gamma ray bursts.

  3. Integrating 2-D position sensitive X-ray detectors with low-density alkali halide storage targets

    NASA Astrophysics Data System (ADS)

    Haubold, H.-G.; Hoheisel, W.; Hiller, P.

    1986-05-01

    For the use in scattering experiments with synchrotron radiation, integrating position sensitive X-ray detectors are discussed. These detectors store the photon number equivalent charge (PNEC) in low-density alkali halide targets. Performance tests are given for a detector which uses a Gd 2O 2S fluorescence screen for X-ray detection and the low-density KCl storage target of a television SEC vidicon tube for photon integration. Rather than directly by X-rays, this target is charged by 6 keV electrons from the image intensifier section of the vidicon. Its excellent storage capability allows measurements of extremely high-contrast, high-flux X-ray patterns with the same accuracy as achieved with any single photon detection system if the discussed readout techniques are applied.

  4. Sealed position sensitive hard X-ray detector having large drift region for all sky camera with high angular resolution

    NASA Technical Reports Server (NTRS)

    Gorenstein, P.; Perlman, D.; Parsignault, D.; Burns, R.

    1979-01-01

    A sealed position sensitive proportional counter filled with two atmospheres of 95% xenon and 5% methane, and containing a drift region of 24 atm cm, has operated in a stable manner for many months. The detector contains G-10 frames to support the anode and cathode wires. The detector was sealed successfully by a combination of vacuum baking the G-10 frames at 150 C for two weeks followed by assembly into the detector in an environment of dry nitrogen, and the use of passive internal getters. The counter is intended for use with a circumferential cylindrical collimator. Together they provide a very broad field of view detection system with the ability to locate cosmic hard X-ray and soft gamma ray sources to an angular precision of a minute of arc. A set of instruments based on this principle have been proposed for satellites to detect and precisely locate cosmic gamma ray bursts.

  5. Intermediate Energies for Nuclear Astrophysics and the Development of a Position Sensitive Microstrip Detector System

    SciTech Connect

    Sobotka, Lee G.; Blackmon, J.; Bertulani, C.

    2015-12-30

    The chemical elements are made at astrophysical sites through a sequence of nuclear reactions often involving unstable nuclei. The overarching aim of this project is to construct a system that allows for the inverse process of nucleosynthesis (i.e. breakup of heavier nuclei into lighter ones) to be studied in high efficiency. The specific problem to be overcome with this grant is inadequate dynamic range and (triggering) threshold to detect the products of the breakup which include both heavy ions (with large energy and large deposited energy in a detector system) and protons (with little energy and deposited energy.) Early on in the grant we provided both TAMU and RIKEN (the site of the eventual experiments) with working systems based on the existing technology. This technology could be used with either an external preamplifier that was to be designed and fabricated by our RIKEN collaborators or upgraded by replacing the existing chip with one we designed. The RIKEN external preamplifier project never can to completion but our revised chip was designed, fabricated, used in a test experiment and performs as required.

  6. CVD-diamond-based position sensitive photoconductive detector for high-flux x-rays and gamma rays.

    SciTech Connect

    Shu, D.

    1999-04-19

    A position-sensitive photoconductive detector (PSPCD) using insulating-type CVD diamond as its substrate material has been developed at the Advanced Photon Source (APS). Several different configurations, including a quadrant pattern for a x-ray-transmitting beam position monitor (TBPM) and 1-D and 2-D arrays for PSPCD beam profilers, have been developed. Tests on different PSPCD devices with high-heat-flux undulator white x-ray beam, as well as with gamma-ray beams from {sup 60}Co sources have been done at the APS and National Institute of Standards and Technology (NIST). It was proven that the insulating-type CVD diamond can be used to make a hard x-ray and gamma-ray position-sensitive detector that acts as a solid-state ion chamber. These detectors are based on the photoconductivity principle. A total of eleven of these TBPMs have been installed on the APS front ends for commissioning use. The linear array PSPCD beam profiler has been routinely used for direct measurements of the undulator white beam profile. More tests with hard x-rays and gamma rays are planned for the CVD-diamond 2-D imaging PSPCD. Potential applications include a high-dose-rate beam profiler for fourth-generation synchrotrons radiation facilities, such as free-electron lasers.

  7. Position-Sensitive CZT Detectors for High Energy X-Ray Astronomy

    NASA Astrophysics Data System (ADS)

    Matteson, J.; Coburn, W.; Heindl, W.; Peterson, L.; Pelling, M.; Rothschild, R.; Skelton, R.; Hink, P.; Slavis, K.

    1998-05-01

    We report recent progress on CZT (Cadmium Zinc Telluride) detectors by the UCSD/WU collaboration. CZT, a room- temperature semiconductor, is a very promising detector material for high energy X-ray astronomy. It can operate from <10 keV to >200 keV, and give sub-keV energy resolution and sub-mm spatial resolution. We have developed an advanced CZT detector that uses two innovations to improve spectral response, give it 3-D localization of energy loss events, and reduce background at high altitudes and in space. The detector measures 12 x 12 x 2 mm(3) and was manufactured by eV Products. Each face has a strip readouts with 500 micron pitch electrodes. The 2 faces' strips are orthogonal, which provides x-y localization into 500 micron pixels. One innovation is "steering electrodes", which are located between the anode strips. They improve the anode charge collection and energy resolution, and tailing due to hole trapping is nearly totally eliminated. The energy resolution at 60 keV is 4 keV and the peak to valley ratio is 50. The other innovation is 3-D localization of energy losses. This is done by comparing the signals from the anode strips, cathode strips, and steering electrodes. There is a strong depth of interaction signature, which can be used to accept events which interact close to the cathode strips (where X-rays of interest are incident) and reject deeper interactions (which are likely to be background). The detector was tested in a balloon flight at 108,000 feet in October 1997. Background was reduced by passive shielding, consisting of lead graded with tin and copper. The lead thickness was changed by command during the flight, and was 7, 2, and 0 mm thick. With the 2 mm thickness the 20 - 40 keV background for the central 30 pixels was 8x10(-4) c/cm(2) -s-keV when the depth of interaction signature was used to reject background, and 7 times greater when this information was not used. The lower background is 12 times less than other workers have obtained

  8. Development of Gamma-Ray Compton Imager Using Room-Temperature 3-D Position Sensitive Semiconductor Detectors

    SciTech Connect

    Zhong He; David Whe; Glenn Knoll

    2003-05-14

    During the three years of this project, two 3-dimensional position sensitive CdZnTe spectrometers were upgraded in collaboration with Johns Hopkins University Applied Physics Laboratory. A prototype Compton-scattering gamma-ray imager was assembled using the two upgraded CdZnTe detectors. The performance of both gamma-ray spectrometers were individually tested. The angular resolution and detection sensitivity of the imaging system were measured using both a point and a line-shaped 137 Cs radiation source. The measurement results are consistent with that obtained from Monte-Carlo simulations performed during the early phase of the project.

  9. Simple technique for measuring the Goos-Hänchen effect with polarization modulation and a position-sensitive detector.

    PubMed

    Gilles, Hervé; Girard, Sylvain; Hamel, Joseph

    2002-08-15

    An original approach to directly measuring the Goos-Hänchen longitudinal shift between TE and TM polarization states during a total internal reflection is introduced. The technique is based on the modulation of the polarization state of a laser by an electro-optic modulator combined with a precise measurement of the resulting spatial displacement with a position-sensitive detector. This method presents many advantages over other techniques and allows measurements at different wavelengths over a broad range for the incident angle.

  10. Two-dimensional position-sensitive detectors for small-angle neutron scattering

    SciTech Connect

    McElhaney, S.A.; Vandermolen, R.I.

    1990-05-01

    In this paper, various detectors available for small angle neutron scattering (SANS) are discussed, along with some current developments being actively pursued. A section has been included to outline the various methodologies of position encoding/decoding with discussions on trends and limitations. Computer software/hardware vary greatly from institute and experiment and only a general discussion is given to this area. 85 refs., 33 figs.

  11. Improving the performance of high-resolution X-ray spectrometers with position-sensitive pixel detectors.

    PubMed

    Huotari, S; Vankó, Gy; Albergamo, F; Ponchut, C; Graafsma, H; Henriquet, C; Verbeni, R; Monaco, G

    2005-07-01

    A dispersion-compensation method to remove the cube-size effect from the resolution function of diced analyzer crystals using a position-sensitive two-dimensional pixel detector is presented. For demonstration, a resolution of 23 meV was achieved with a spectrometer based on a 1 m Rowland circle and a diced Si(555) analyzer crystal in a near-backscattering geometry, with a Bragg angle of 88.5 degrees . In this geometry the spectrometer equipped with a traditional position-insensitive detector provides a resolution of 190 meV. The dispersion-compensation method thus allows a substantial increase in the resolving power without any loss of signal intensity.

  12. Evaluation of the x-ray response of a position-sensitive microstrip detector with an integrated readout chip

    SciTech Connect

    Rossington, C.; Jaklevic, J.; Haber, C.; Spieler, H. ); Reid, J. . Dept. of Physics)

    1990-08-01

    The performance of an SVX silicon microstrip detector and its compatible integrated readout chip have been evaluated in response to Rh K{alpha} 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.

  13. Characterization of multipoint diffraction strain and tilt sensor based on moire interferometer and multichannel imaging position-sensitive detector

    SciTech Connect

    Iqbal, Salman; Asundi, Anand

    2006-11-15

    A multipoint diffraction strain and tilt sensor using a multichannel imaging position-sensitive detector has been developed and characterized, with the novel feature of simultaneous measurement of strain and tilt at a large array of points. Unlike conventional interferometry based systems, this new whole-field measurement system uses principles of diffraction to directly measure strain at the desired points. The system utilizes a moire interferometer for the generation of two coherent and symmetric beams, which illuminate a high-frequency diffraction grating, bonded on the surface of the sample under test. The core of the system is a charge coupled device camera fitted with an array of microlenses, which samples the diffracted beam into an array of beamlets. The camera with lens array, which is being used as array-type multichannel position-sensitive detectors, senses the shift of the individual microspots. The deviation is then processed and the normal and shear strains are calculated at that spot along with rigid-body tilt. The combined results are graphically shown to the user as two-dimensional strain and tilt maps. Simultaneous strain measurement at more than 1300 points has been successfully obtained with the spatial resolution of better than 150 {mu}m. This novel technique has many useful features compared to other whole-field optical strain measurement techniques and is expected to be very valuable in experimental mechanics of microsystems and devices.

  14. Development of a Position Sensitive Liquid Scintillator Bar-type Detector

    NASA Astrophysics Data System (ADS)

    Atencio, Ariella; Cizewski, Jolie; Walter, David; Chipps, Kelly; Febbraro, Michael; Pain, Steven; Smith, Karl; Thornsberry, Cory

    2016-09-01

    The ability to detect neutrons is important for both nuclear reactions and beta decay. Liquid scintillators have the useful property of Pulse Shape Discrimination(PSD), which can be used to separate gamma-ray-induced events when the scintillators are used as neutron detectors. Because of their ability to apply PSD, these liquid scintillators will have many applications in neutron detection, such as a recent experiment conducted at the University of Notre Dame. The liquid scintillators use a xylene based liquid made in-house at Oak Ridge National Laboratory. Naphthalene in the liquid scintillator improves the light output properties of the scintillator. An optimized method for the purification of naphthalene will be discussed as well as the first implementation of an array of these detectors. This work is supported in part by the NSF and the U.S. DOE. Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy.

  15. Thermal Neutron Imaging Using A New Pad-Based Position Sensitive Neutron Detector

    SciTech Connect

    Dioszegi I.; Vanier P.E.; Salwen C.; Chichester D.L.; Watson S.M.

    2016-10-29

    Thermal neutrons (with mean energy of 25 meV) have a scattering mean free path of about 20 m in air. Therefore it is feasible to find localized thermal neutron sources up to ~30 m standoff distance using thermal neutron imaging. Coded aperture thermal neutron imaging was developed in our laboratory in the nineties, using He-3 filled wire chambers. Recently a new generation of coded-aperture neutron imagers has been developed. In the new design the ionization chamber has anode and cathode planes, where the anode is composed of an array of individual pads. The charge is collected on each of the individual 5x5 mm2 anode pads, (48x48 in total, corresponding to 24x24 cm2 sensitive area) and read out by application specific integrated circuits (ASICs). The high sensitivity of the ASICs allows unity gain operation mode. The new design has several advantages for field deployable imaging applications, compared to the previous generation of wire-grid based neutron detectors. Among these are the rugged design, lighter weight and use of non-flammable stopping gas. For standoff localization of thermalized neutron sources a low resolution (11x11 pixel) coded aperture mask has been fabricated. Using the new larger area detector and the coarse resolution mask we performed several standoff experiments using moderated californium and plutonium sources at Idaho National Laboratory. In this paper we will report on the development and performance of the new pad-based neutron camera, and present long range coded-aperture images of various thermalized neutron sources.

  16. High-Efficiency CdZnTe Position-Sensitive VFG Gamma-Ray Detectors for Safeguards Applications

    SciTech Connect

    Bolotnikov, Aleksey E.; James, Ralph B.; Cui, Y.; De Geronimo, G.; Vernon, E.; Camarda, G. S.; Hossain, A.; Yang, G.; Indusi, J.; Boyer, Brian

    2015-09-30

    The goal of this project is to incorporate a Cadmium-Zinc-Telluride (CdZnTe or CZT) detector (with 1% or better resolution) into a bench-top prototype for isotope identification and related safeguards applications. The bench-top system is based on a 2x2 array of 6x6x20 mm3 position-sensitive virtual Frisch-grid (VFG) CZT detectors. The key features of the array are that it allows for the use of average-grade CZT material with a moderate content of defects, and yet it provides high energy resolution, 1% FWHM at 662 keV, large effective area, and low-power consumption. The development of this type of 3D detector and new instruments incorporating them is motivated by the high cost and low availability of large, > 1 cm3, CZT crystals suitable for making multi-pixel detectors with acceptable energy resolution and efficiency.

  17. Large angle solid state position sensitive x-ray detector system

    DOEpatents

    Kurtz, David S.; Ruud, Clay O.

    1998-01-01

    A method and apparatus for x-ray measurement of certain properties of a solid material. In distinction to known methods and apparatus, this invention employs a specific fiber-optic bundle configuration, termed a reorganizer, itself known for other uses, for coherently transmitting visible light originating from the scintillation of diffracted x-radiation from the solid material gathered along a substantially one dimensional linear arc, to a two-dimensional photo-sensor array. The two-dimensional photodetector array, with its many closely packed light sensitive pixels, is employed to process the information contained in the diffracted radiation and present the information in the form of a conventional x-ray diffraction spectrum. By this arrangement, the angular range of the combined detector faces may be increased without loss of angular resolution. Further, the prohibitively expensive coupling together of a large number of individual linear diode photodetectors, which would be required to process signals generated by the diffracted radiation, is avoided.

  18. Large angle solid state position sensitive x-ray detector system

    DOEpatents

    Kurtz, D.S.; Ruud, C.O.

    1998-03-03

    A method and apparatus for x-ray measurement of certain properties of a solid material are disclosed. In distinction to known methods and apparatus, this invention employs a specific fiber-optic bundle configuration, termed a reorganizer, itself known for other uses, for coherently transmitting visible light originating from the scintillation of diffracted x-radiation from the solid material gathered along a substantially one dimensional linear arc, to a two-dimensional photo-sensor array. The two-dimensional photodetector array, with its many closely packed light sensitive pixels, is employed to process the information contained in the diffracted radiation and present the information in the form of a conventional x-ray diffraction spectrum. By this arrangement, the angular range of the combined detector faces may be increased without loss of angular resolution. Further, the prohibitively expensive coupling together of a large number of individual linear diode photodetectors, which would be required to process signals generated by the diffracted radiation, is avoided. 7 figs.

  19. Large angle solid state position sensitive x-ray detector system

    DOEpatents

    Kurtz, David S.; Ruud, Clay O.

    1998-01-01

    A method and apparatus for x-ray measurement of certain properties of a solid material. In distinction to known methods and apparatus, this invention employs a specific fiber-optic bundle configuration, termed a reorganizer, itself known for other uses, for coherently transmitting visible light originating from the scintillation of diffracted x-radiation from the solid material gathered along a substantially one dimensional linear arc, to a two-dimensional photo-sensor array. The two-dimensional photodetector array, with its many closely packed light sensitive pixels, is employed to process the information contained in the diffracted radiation and present the information in the form of a conventional x-ray diffraction spectrum. By this arrangement, the angular range of the combined detector faces may be increased without loss of angular resolution. Further, the prohibitively expensive coupling together of a large number of individual linear diode photodetectors, which would be required to process signals generated by the diffracted radiation, is avoided.

  20. Large angle solid state position sensitive x-ray detector system

    DOEpatents

    Kurtz, D.S.; Ruud, C.O.

    1998-07-21

    A method and apparatus are disclosed for x-ray measurement of certain properties of a solid material. In distinction to known methods and apparatus, this invention employs a specific fiber-optic bundle configuration, termed a reorganizer, itself known for other uses, for coherently transmitting visible light originating from the scintillation of diffracted x-radiation from the solid material gathered along a substantially one dimensional linear arc, to a two-dimensional photo-sensor array. The two-dimensional photodetector array, with its many closely packed light sensitive pixels, is employed to process the information contained in the diffracted radiation and present the information in the form of a conventional x-ray diffraction spectrum. By this arrangement, the angular range of the combined detector faces may be increased without loss of angular resolution. Further, the prohibitively expensive coupling together of a large number of individual linear diode photodetectors, which would be required to process signals generated by the diffracted radiation, is avoided. 7 figs.

  1. Development of a position sensitive X-ray detector for use in a light weight X-ray diffractometer

    NASA Technical Reports Server (NTRS)

    Semmler, R. A.

    1971-01-01

    A position sensitive proportional counter for use in an X-ray diffractometer is developed to permit drastic reductions in the power and weight requirements of the X-ray source and the elimination of the power, weight, and complexity of a moving slit. The final detector constructed and tested has a window spanning 138 and a free standing anode curved along an arc of 7.1 cm radius. Demonstration spectra of a quartz sample in a Debye-Sherrer geometry indicate a spatial resolution of 0.4 - 0.5 mm (0.3 - 0.4 theta). The lunar diffractometer consumed 25 watts in the X-ray generator and weighed about 20 pounds.

  2. A zero dead-time multi-particle time and position sensitive detector based on correlation between brightness and amplitude

    NASA Astrophysics Data System (ADS)

    Urbain, X.; Bech, D.; Van Roy, J.-P.; Géléoc, M.; Weber, S. J.; Huetz, A.; Picard, Y. J.

    2015-02-01

    A new multi-particle time and position sensitive detector using only a set of microchannel plates, a waveform digitizer, a phosphor screen, and a CMOS camera is described. The assignment of the timing information, as taken from the microchannel plates by fast digitizing, to the positions, as recorded by the camera, is based on the COrrelation between the BRightness of the phosphor screen spots, defined as their integrated intensity and the Amplitude of the electrical signals (COBRA). Tests performed by observing the dissociation of HeH, the fragmentation of H3 into two or three fragments, and the photo-double-ionization of Xenon atoms are presented, which illustrate the performances of the COBRA detection scheme.

  3. A zero dead-time multi-particle time and position sensitive detector based on correlation between brightness and amplitude.

    PubMed

    Urbain, X; Bech, D; Van Roy, J-P; Géléoc, M; Weber, S J; Huetz, A; Picard, Y J

    2015-02-01

    A new multi-particle time and position sensitive detector using only a set of microchannel plates, a waveform digitizer, a phosphor screen, and a CMOS camera is described. The assignment of the timing information, as taken from the microchannel plates by fast digitizing, to the positions, as recorded by the camera, is based on the COrrelation between the BRightness of the phosphor screen spots, defined as their integrated intensity and the Amplitude of the electrical signals (COBRA). Tests performed by observing the dissociation of HeH, the fragmentation of H3 into two or three fragments, and the photo-double-ionization of Xenon atoms are presented, which illustrate the performances of the COBRA detection scheme.

  4. A zero dead-time multi-particle time and position sensitive detector based on correlation between brightness and amplitude

    SciTech Connect

    Urbain, X. Bech, D.; Van Roy, J.-P.; Géléoc, M.; Weber, S. J.

    2015-02-15

    A new multi-particle time and position sensitive detector using only a set of microchannel plates, a waveform digitizer, a phosphor screen, and a CMOS camera is described. The assignment of the timing information, as taken from the microchannel plates by fast digitizing, to the positions, as recorded by the camera, is based on the COrrelation between the BRightness of the phosphor screen spots, defined as their integrated intensity and the Amplitude of the electrical signals (COBRA). Tests performed by observing the dissociation of HeH, the fragmentation of H{sub 3} into two or three fragments, and the photo-double-ionization of Xenon atoms are presented, which illustrate the performances of the COBRA detection scheme.

  5. Performance measurements of a depth-encoding PET detector module based on position-sensitive avalanche photodiode read-out.

    PubMed

    Dokhale, P A; Silverman, R W; Shah, K S; Grazioso, R; Farrell, R; Glodo, J; McClish, M A; Entine, G; Tran, V H; Cherry, S R

    2004-09-21

    We are developing a high-resolution, high-efficiency positron emission tomography (PET) detector module with depth of interaction (DOI) capability based on a lutetium oxyorthosilicate (LSO) scintillator array coupled at both ends to position-sensitive avalanche photodiodes (PSAPDs). In this paper we present the DOI resolution, energy resolution and timing resolution results for complete detector modules. The detector module consists of a 7 x 7 matrix of LSO scintillator crystals (1 x 1 x 20 mm3 in dimension) coupled to 8 x 8 mm2 PSAPDs at both ends. Flood histograms were acquired and used to generate crystal look-up tables. The DOI resolution was measured for individual crystals within the array by using the ratio of the signal amplitudes from the two PSAPDs on an event-by-event basis. A measure of the total scintillation light produced was obtained by summing the signal amplitudes from the two PSAPDs. This summed signal was used to measure the energy resolution. The DOI resolution was measured to be 3-4 mm FWHM irrespective of the position of the crystal within the array, or the interaction location along the length of the crystal. The total light signal and energy resolution was almost independent of the depth of interaction. The measured energy resolution averaged 14% FWHM. The coincidence timing resolution measured using a pair of identical detector modules was 4.5 ns FWHM. These results are consistent with the design goals and the performance required of a compact, high-resolution and high-efficiency PET detector module for small animal and breast imaging applications.

  6. A study of the timing properties of position-sensitive avalanche photodiodes

    PubMed Central

    Wu, Yibao; Ng, Thomas SC; Yang, Yongfeng; Shah, Kanai; Farrell, Richard; Cherry, Simon R

    2009-01-01

    In this paper we study position-dependent timing shifts and timing resolution in position sensitive avalanche photodiodes (PSAPDs) and their effect on the coincidence window used in positron emission tomography (PET) systems using these devices. There is a delay in PSAPD signals that increases as the excitation position moves from the corner to the center of the device and the timing resolution concurrently worsens. The difference in timing between the center and corner can be up to 30.7 ns for a 14×14 mm2 area PSAPD. This means that a PSAPD-based PET system could require a very wide coincidence timing window (>60 ns) if this effect is not corrected, although the individual crystal pairs still have full-width half-maximum (FWHM) timing resolutions better than 7.4 ns. In addition to characterizing the timing properties of PSAPDs, two correction methods were developed and applied to data from a pair of PSAPD detectors. These two timing offset corrections reduced the timing shift of a crystal pair from 52.4 ns to 9.7 ns or 1.3 ns, improved FWHM timing resolution of the detector pair from 24.6 ns to 9.5 ns or 6.0 ns and reduced the timing window (sufficient to cover at least twice the FWHM for all crystal pairs) from 65.1 ns to 22.0 ns or 15.2 ns respectively. A two-step timing alignment method is proposed for a PET system consisting of multiple PSAPDs. Lastly, the effect of PSAPD size on the timing performance was also evaluated. PMID:19671971

  7. A study of the timing properties of position-sensitive avalanche photodiodes.

    PubMed

    Wu, Yibao; Ng, Thomas S C; Yang, Yongfeng; Shah, Kanai; Farrell, Richard; Cherry, Simon R

    2009-09-07

    In this paper, we study position-dependent timing shifts and timing resolution in position sensitive avalanche photodiodes (PSAPDs) and their effects on the coincidence window used in positron emission tomography (PET) systems using these devices. There is a delay in PSAPD signals that increases as the excitation position moves from the corner to the center of the device and the timing resolution concurrently worsens. The difference in timing between the center and the corner can be up to 30.7 ns for a 14 x 14 mm(2) area PSAPD. This means that a PSAPD-based PET system could require a very wide coincidence timing window (>60 ns) if this effect is not corrected, although the individual crystal pairs still have full-width half-maximum (FWHM) timing resolutions better than 7.4 ns. In addition to characterizing the timing properties of PSAPDs, two correction methods were developed and applied to data from a pair of PSAPD detectors. These two timing offset corrections reduced the timing shift of a crystal pair from 52.4 ns to 9.7 ns or 1.3 ns, improved the FWHM timing resolution of the detector pair from 24.6 ns to 9.5 ns or 6.0 ns and reduced the timing window (sufficient to cover at least twice the FWHM for all crystal pairs) from 65.1 ns to 22.0 ns or 15.2 ns, respectively. A two-step timing alignment method is proposed for a PET system consisting of multiple PSAPDs. Lastly, the effect of PSAPD size on the timing performance was also evaluated.

  8. Data processing in neutron protein crystallography using position-sensitive detectors

    SciTech Connect

    Schoenborn, B.P.

    1982-01-01

    Neutrons provide a unique probe for localizing hydrogen atoms and for distinguishing hydrogen from deuterons. Hydrogen atoms largely determine the three-dimensional structure of proteins and are responsible for many catalytic reactions. The study of hydrogen bonding and hydrogen exchange will therefore give insight into reaction mechanisms and conformational fluctuations. In addition, neutrons provide the ability to distinguish N from C and O and to allow correct orientation of groups such as histidine and glutamine. To take advantage of these unique features of neutron crystallography, one needs accurate Fourier maps depicting atomic structure to a high precision. In this paper, techniques are described for minimizing error in the observed structure factors by optimizing data collection and analysis procedures. Special attention is given to subtraction of the high background associated with hydrogen-containing molecules, which produces a disproportionately large statistical error.

  9. A CdTe position sensitive detector for a hard X- and gamma-ray wide field camera

    SciTech Connect

    Caroli, E.; Cesare, G. de; Donati, A.; Dusi, W.; Landini, G.; Stephen, J.B.; Perotti, F.

    1998-12-31

    An important region of the electromagnetic spectrum for astrophysics is the hard X- and gamma ray band between 10 keV and a few MeV, where several processes occur in a wide variety of objects and with different spatial distribution and time scales. In order to fulfill the observational requirements in this energy range and taking into account the opportunities given by small/medium size missions (e.g., on the ISS), the authors have proposed a compact, wide field camera based on a thick (1 cm) position sensitive CdTe detector (PSD). The detector is made of an array of 128x96 CdTe microspectrometers with a pixel size of 2x2 mm{sup 2}. The basic element of the PSD is the linear module that is an independent detection unit with 32 CdTe crystals and monolithic front-electronics (ASIC) supported by a thin (300 {micro}m) ceramic layer. The expected performance of the PSD over the operative energy range and some of the required ASIC functionality are presented and discussed.

  10. Fast x-ray scattering measurements on molten alumina using a 120° curved position sensitive detector

    NASA Astrophysics Data System (ADS)

    Hennet, Louis; Thiaudière, Dominique; Gailhanou, Marc; Landron, Claude; Coutures, Jean-Pierre; Price, David L.

    2002-01-01

    Fast x-ray scattering measurements on molten alumina were performed on the H10 beam line at the DCI Synchrotron of LURE (Orsay, France). A high-temperature chamber with a levitation device was coupled with the four-circle goniometer of the beam line. A 100 W CO2 laser was used to melt the sample and the temperature was measured using an optical pyrometer operating at 0.85 μm. Usually, measurements of the total structure factor S(Q) on molten materials are performed using a fixed detector scanned over an angular range. In this work, in order to reduce the total scan duration, x-ray scattered intensities were measured with a 120° position sensitive detector (INEL CPS120). We performed several measurements with different acquisition times varying from 10 s to 5 min. In 5 min it was possible to obtain a good determination of S(Q) with a usable signal up to the Q range limit (13 Å-1). The intensity was comparable with a 1 h measurement with a NaI (Tl) scintillator scanned over the 120° 2θ range. On reducing the counting time the statistics are degraded and the data are noisier, especially in the high Q region. Nevertheless, even with 10 s, the S(Q) data remain usable and give good results. Performing the Fourier transformation of S(Q), we obtain similar reliable pair-correlation functions with both 5 min and 10 s acquisition times.

  11. Development of a Position Sensitive Microstrip Detector System and its Readout Electronics Using ASICs Technologies for SAMURAI

    NASA Astrophysics Data System (ADS)

    Saastamoinen, A.; Baba, H.; Blackmon, J. C.; Elson, J.; Kurokawa, M.; McCleskey, M.; Otsu, H.; Rasco, B. C.; Roeder, B. T.; Sobotka, L. G.; Trache, L.; Tribble, R. E.; Yoneda, K.; Zenihiro, J.

    We are building a Si detector tracker system for the SAMURAI spectrometer. Characterizing the behavior of the detectors and associated electronics is essential for properly analyzing the future experimental results. We have performed test experiments to study the detector system response to heavy ion and proton beams of various energies. In this contribution we present some of the results and give an outlook of the future plans.

  12. A Study of Position-Sensitive Solid-State Photomultiplier Signal Properties.

    PubMed

    Schmall, Jeffrey P; Du, Junwei; Judenhofer, Martin S; Dokhale, Purushottam; Christian, James; McClish, Mickel; Shah, Kanai S; Cherry, Simon R

    2014-06-12

    We present an analysis of the signal properties of a position-sensitive solid-state photomultiplier (PS-SSPM) that has an integrated resistive network for position sensing. Attractive features of PS-SSPMs are their large area and ability to resolve small scintillator crystals. However, the large area leads to a high detector capacitance, and in order to achieve high spatial resolution a large network resistor value is required. These inevitably create a low-pass filter that drastically slows what would be a fast micro-cell discharge pulse. Significant changes in the signal shape of the PS-SSPM cathode output as a function of position are observed, which result in a position-dependent time delay when using traditional time pick-off methods such as leading edge discrimination and constant fraction discrimination. The timing resolution and time delay, as a function of position, were characterized for two different PS-SSPM designs, a continuous 10 mm × 10 mm PS-SSPM and a tiled 2 × 2 array of 5 mm × 5 mm PS-SSPMs. After time delay correction, the block timing resolution, measured with a 6 × 6 array of 1.3 × 1.3 × 20 mm(3) LSO crystals, was 8.6 ns and 8.5 ns, with the 10 mm PS-SSPM and 5 mm PS-SSPM respectively. The effect of crystal size on timing resolution was also studied, and contrary to expectation, a small improvement was measured when reducing the crystal size from 1.3 mm to 0.5 mm. Digital timing methods were studied and showed great promise for allowing accurate timing by implementation of a leading edge time pick-off. Position-dependent changes in signal shape on the anode side also are present, which complicates peak height data acquisition methods used for positioning. We studied the effect of trigger position on signal amplitude, flood histogram quality, and depth-of-interaction resolution in a dual-ended readout detector configuration. We conclude that detector timing and positioning can be significantly improved by implementation of digital timing

  13. A data acquisition system for two-dimensional position sensitive micropattern gas detectors with delay-line readout

    NASA Astrophysics Data System (ADS)

    Hanu, A. R.; Prestwich, W. V.; Byun, S. H.

    2015-04-01

    We present a data acquisition (DAQ) system for two-dimensional position sensitive micropattern gas detectors using the delay-line method for readout. The DAQ system consists of a field programmable gate array (FPGA) as the main data processor and our time-to-digital (TDC) mezzanine card for making time measurements. We developed the TDC mezzanine card around the Acam TDC-GPX ASIC and it features four independent stop channels referenced to a common start, a typical timing resolution of ~81 ps, and a 17-bit measurement range, and is compliant with the VITA 57.1 standard. For our DAQ system, we have chosen the Xilinx SP601 development kit which features a single Spartan 6 FPGA, 128 MB of DDR2 memory, and a serial USB interface for communication. Output images consist of 1024×1024 square pixels, where each pixel has a 32-bit depth and corresponds to a time difference of 162 ps relative to its neighbours. When configured for a 250 ns acquisition window, the DAQ can resolve periodic event rates up to 1.8×106 Hz without any loses and will report a maximum event rate of 6.11×105 Hz for events whose arrival times follow Poisson statistics. The integral and differential non-linearities have also been measured and are better than 0.1% and 1.5%, respectively. Unlike commercial units, our DAQ system implements the delay-line image reconstruction algorithm entirely in hardware and is particularly attractive for its modularity, low cost, ease of integration, excellent linearity, and high throughput rate.

  14. Characterization of a sub-assembly of 3D position sensitive cadmium zinc telluride detectors and electronics from a sub-millimeter resolution PET system.

    PubMed

    Abbaszadeh, Shiva; Gu, Yi; Reynolds, Paul D; Levin, Craig S

    2016-09-21

    Cadmium zinc telluride (CZT) offers key advantages for small animal positron emission tomography (PET), including high spatial and energy resolution and simple metal deposition for fabrication of very small pixel arrays. Previous studies have investigated the intrinsic spatial, energy, and timing resolution of an individual sub-millimeter resolution CZT detector. In this work we present the first characterization results of a system of these detectors. The 3D position sensitive dual-CZT detector module and readout electronics developed in our lab was scaled up to complete a significant portion of the final PET system. This sub-system was configured as two opposing detection panels containing a total of twelve [Formula: see text] mm monolithic CZT crystals for proof of concept. System-level characterization studies, including optimizing the trigger threshold of each channel's comparators, were performed. (68)Ge and (137)Cs radioactive isotopes were used to characterize the energy resolution of all 468 anode channels in the sub-system. The mean measured global 511 keV photopeak energy resolution over all anodes was found to be [Formula: see text]% FWHM after correction for photon interaction depth-dependent signal variation. The measured global time resolution was 37 ns FWHM, a parameter to be further optimized, and the intrinsic spatial resolution was 0.76 mm FWHM.

  15. Characterization of a sub-assembly of 3D position sensitive cadmium zinc telluride detectors and electronics from a sub-millimeter resolution PET system

    NASA Astrophysics Data System (ADS)

    Abbaszadeh, Shiva; Gu, Yi; Reynolds, Paul D.; Levin, Craig S.

    2016-09-01

    Cadmium zinc telluride (CZT) offers key advantages for small animal positron emission tomography (PET), including high spatial and energy resolution and simple metal deposition for fabrication of very small pixel arrays. Previous studies have investigated the intrinsic spatial, energy, and timing resolution of an individual sub-millimeter resolution CZT detector. In this work we present the first characterization results of a system of these detectors. The 3D position sensitive dual-CZT detector module and readout electronics developed in our lab was scaled up to complete a significant portion of the final PET system. This sub-system was configured as two opposing detection panels containing a total of twelve 40~\\text{mm}× 40~\\text{mm}× 5 mm monolithic CZT crystals for proof of concept. System-level characterization studies, including optimizing the trigger threshold of each channel’s comparators, were performed. 68Ge and 137Cs radioactive isotopes were used to characterize the energy resolution of all 468 anode channels in the sub-system. The mean measured global 511 keV photopeak energy resolution over all anodes was found to be 7.35+/- 1.75 % FWHM after correction for photon interaction depth-dependent signal variation. The measured global time resolution was 37 ns FWHM, a parameter to be further optimized, and the intrinsic spatial resolution was 0.76 mm FWHM.

  16. Gas-filled position-sensitive detectors of thermal neutrons at the Konstantinov Petersburg Nuclear Physics Institute of the Russian Academy of Sciences

    NASA Astrophysics Data System (ADS)

    Andreev, V. A.; Ganzha, G. A.; Ivanov, E. A.; Ilyin, D. S.; Kovalenko, S. N.; Kolkhidashvili, M. R.; Krivshich, A. G.; Nadtochy, A. V.; Runov, V. V.; Soloveĭ, V. A.; Shabanov, G. D.

    2010-05-01

    The manufacturing line for the development and fabrication of position-sensitive detectors of thermal neutrons has been organized at the Petersburg Nuclear Physics Institute of the Russian Academy of Sciences. Three detectors with sensitive regions 300 × 170 (prototype), 200 × 200, and 300 × 300 mm in size have been constructed to date. The detectors represent multiwire proportional chambers with cathode data readout to a delay line. The devices are filled with the 3He/CF4 gas mixture. These detectors are intended for modernizing the detector systems of the Vector and Membrana-2 diffractometers (VVR-M reactor, Konstantinov Petersburg Nuclear Physics Institute of the Russian Academy of Sciences, Gatchina, Russia).

  17. A two-dimensional position sensitive charged-particle detector for the magnetic spectrograph ``Big Karl'' of the Jülich Cyclotron ``Jülich''

    NASA Astrophysics Data System (ADS)

    Köhler, M.; Müller, K. D.; Stoff, H.; Teske, M.; Berg, G. P. A.; Hardt, A.; Martin, S.; Mayer-Böricke, C.; Meißburger, J.

    1980-09-01

    A two-dimensional position sensitive detector with an area of 300 mm × 40 mm and a charged-particle spatial resolution of ΔX = ΔY ⩽ 0.5 mm is described. Some test results point out the detector properties. Results of the experiments 102Ru(d,p) 103Ru and 208Pb(p,p') 208Pb done at 45 MeV incident particle energy using the magnetic spectrograph BIG KARL are shown with sections of the proton spectra.

  18. Note: A two-dimensional position-sensitive micro-channel plate detector with a cross-connected-pixels resistive anode and integrated spectroscopy amplifiers.

    PubMed

    Yang, Liping; Liu, Junliang; Zhang, Yuezhao; Wang, Wei; Yu, Deyang; Li, Xiaoxiao; Li, Xin; Zheng, Min; Ding, Baowei; Cai, Xiaohong

    2017-08-01

    Based on the charge-division method, a compact detector system for charged particles is constructed. The system consists of a pair of micro-channel plates, a novel two-dimensional position-sensitive cross-connected-pixels resistive anode, and specially designed front-end electronics that can directly drive analog-to-digital converters. The detector is tested with an (241)Am α-source. A position resolution of better than 0.3 mm and a maximum distortion within 0.5 mm in the active dimensions of 100 mm diameter are achieved.

  19. Development and applications of a new neutron single-crystal diffractometer based on a two-dimensional large-area curved position-sensitive detector

    PubMed Central

    Lee, Chang-Hee; Noda, Yukio; Ishikawa, Yoshihisa; Kim, Shin Ae; Moon, Myungkook; Kimura, Hiroyuki; Watanabe, Masashi; Dohi, Yuki

    2013-01-01

    A new single-crystal neutron diffractometer based on a large-area curved two-dimensional position-sensitive detector (C-2DPSD) has been developed. The diffractometer commissioning is almost complete, together with development of the measurement methodology and the raw data processing software package, the Reciprocal Analyzer, and the instrument is now ready to be launched for users. Position decoding of the C-2DPSD is via a delay-line readout method with an effective angular range of 110 × 54° in the horizontal and vertical directions, respectively, with a nominal radius of curvature of 530 mm. The diffractometer is equipped with a Ge(311) mosaic monochromator and two supermirror vacuum guide paths, one before and one after the monochromator position. The commissioning incorporates corrections and calibration of the instrument using an NaCl crystal, various applications such as crystallographic and magnetic structure measurements, a crystallinity check on large crystals, and a study on the composition or dopant content of a mixed crystal of (TmxYb1−x)Mn2O5. The installation of the diffractometer and the measurement method, the calibration procedure and results, the raw data treatment and visualization, and several applications using the large C-2DPSD-based diffractometer are reported. PMID:23682194

  20. Effects of dead time on quantitative dual-energy imaging using a position-sensitive spectroscopic detector

    NASA Astrophysics Data System (ADS)

    Dummott, Louise M.; Schettino, Giuseppe; Seller, Paul; Wilson, Matthew D.; Veale, Matthew C.; Pani, Silvia

    2017-03-01

    Dual energy imaging (DE) is a potential alternative to conventional mammography for patients with dense breasts. It requires intravenous injection of contrast agent (CA) and subsequent acquisition of images at two different energies. Each pixel is seen as a vector and is projected onto a two-material basis, e.g. water, CA, to form separate water-equivalent and CA-equivalent images. On conventional detectors, this requires two separate exposures. Spectroscopic detectors allow multiple images from a single exposure by integrating appropriate energy bands. This work investigates the effects of high count rates on quantitative DE imaging using a CdTe spectroscopic detector. Because of its small pixel size (250 μm), a limitation of the detector is charge sharing between pixels, which must be corrected to avoid degradation of the detected spectrum. However, as charge sharing is identified by neighbouring pixels registering a count in a given readout frame, an effective maximum count rate (EMR) is imposed, above which linearity between incident and detected counts is lost. A simulation was used to model detector response of a test object composed of water and iodine, with different EMRs and incident count rates. Using a known iodine thickness of 0.03 cm, and an EMR of 103 s-1 , the reconstructed thickness of iodine was found to be 97%, 74% and 24% of the true value for incident count rates of 100, 1000 and 10000 photons/pixel/s respectively. The simulation was validated by imaging a water-equivalent test phantom containing iodinated CA at different X-ray currents, to determine the optimum beam conditions.

  1. Sub-nanosecond multi-channel time-to-digital converter for the 2-D position-sensitive neutron detectors at TriCS and AMOR

    NASA Astrophysics Data System (ADS)

    Buehler, Ch.; Greuter, U.; Frey, G.; Zaharko, O.; Koennecke, M.; Schefer, J.; Rasmussen, P.; Schaniel, D.; Clemens, D.; Gabriel, A.; Felsche, J.; Schlumpf, N.

    We have developed an ultra-fast multi-channel time-to-digital converter (mC-TDC). The mC-TDC electronics is used to read out the delay-line-based 2-D detectors of the neutron diffractometer and reflectometer TriCS and AMOR, respectively. The high time resolution of the mC-TDC ( 145 ps) allows the conversion of the position-sensitive detector signals into accurate 2-D scattering coordinates ( 2×2 mm2). The mC-TDC also generates low-jitter time-of-flight signals and incorporates an efficient two-stage pileup-rejection mechanism. Neutron rates exceeding 100000cps can be processed.

  2. Note: A two-dimensional position-sensitive micro-channel plate detector with a cross-connected-pixels resistive anode and integrated spectroscopy amplifiers

    NASA Astrophysics Data System (ADS)

    Yang, Liping; Liu, Junliang; Zhang, Yuezhao; Wang, Wei; Yu, Deyang; Li, Xiaoxiao; Li, Xin; Zheng, Min; Ding, Baowei; Cai, Xiaohong

    2017-08-01

    Based on the charge-division method, a compact detector system for charged particles is constructed. The system consists of a pair of micro-channel plates, a novel two-dimensional position-sensitive cross-connected-pixels resistive anode, and specially designed front-end electronics that can directly drive analog-to-digital converters. The detector is tested with an 241Am α-source. A position resolution of better than 0.3 mm and a maximum distortion within 0.5 mm in the active dimensions of 100 mm diameter are achieved.

  3. Note: A large open ratio, time, and position sensitive detector for time of flight measurements in UHV.

    PubMed

    Lupone, S; Damoy, S; Husseen, A; Briand, N; Debiossac, M; Tall, S; Roncin, P

    2015-12-01

    We report on the construction of an UHV compatible 40 mm active diameter detector based on micro channel plates and assembled directly on the feed-throughs of a DN63CF flange. It is based on the charge division technique and uses a standard 2 inch Si wafer as a collector. The front end electronic is placed directly on the air side of the flange allowing excellent immunity to noise and a very good timing signal with reduced ringing. The important aberrations are corrected empirically providing an absolute positioning accuracy of 500 μm while a 150 μm resolution is measured in the center.

  4. Note: A large open ratio, time, and position sensitive detector for time of flight measurements in UHV

    SciTech Connect

    Lupone, S.; Damoy, S.; Husseen, A.; Briand, N.; Debiossac, M.; Tall, S.; Roncin, P.

    2015-12-15

    We report on the construction of an UHV compatible 40 mm active diameter detector based on micro channel plates and assembled directly on the feed-throughs of a DN63CF flange. It is based on the charge division technique and uses a standard 2 inch Si wafer as a collector. The front end electronic is placed directly on the air side of the flange allowing excellent immunity to noise and a very good timing signal with reduced ringing. The important aberrations are corrected empirically providing an absolute positioning accuracy of 500 μm while a 150 μm resolution is measured in the center.

  5. The 10B based Jalousie neutron detector - An alternative for 3He filled position sensitive counter tubes

    NASA Astrophysics Data System (ADS)

    Henske, M.; Klein, M.; Köhli, M.; Lennert, P.; Modzel, G.; Schmidt, C. J.; Schmidt, U.

    2012-09-01

    Over the last decades 3He filled proportional counter tubes were the working horse employed to serve as neutron counters especially in cases where large area coverage was required. Today the lack of 3He demands the development of an alternative technology. Here we present a prototype neutron detector that is based on a concept with solid 10B as neutron converter and aims for large area neutron detection applications. We report on first experimental results obtained with this prototype to demonstrate the feasibility and operational readiness of our concept.

  6. Position-sensitive multi-wavelength photon detectors based on epitaxial InGaAs/InAlAs quantum wells

    NASA Astrophysics Data System (ADS)

    Ganbold, T.; Antonelli, M.; Cautero, G.; Menk, R. H.; Cucini, R.; Biasiol, G.

    2015-09-01

    Beam monitoring in synchrotron radiation or free electron laser facilities is extremely important for calibration and diagnostic issues. Here we propose an in-situ detector showing fast response and homogeneity for both diagnostics and calibration purposes. The devices are based on In0.75Ga0.25As/In0.75Al0.25As QWs, which offer several advantages due to their direct, low-energy band gap and high electron mobility at room temperature. A pixelation structure with 4 quadrants was developed on the back surface of the device, in order to fit commercially available readout chips. The QW devices have been tested with collimated monochromatic X-ray beams from synchrotron radiation. A rise in the current noise with positive bias was observed, which could be due to deep traps for hole carriers. Therefore, an optimized negative bias was chosen to minimize dark currents and noise. A decrease in charge collection efficiency was experienced as the beam penetrates into deeper layers, where a dislocation network is present. The prototype samples showed that individual currents obtained from each quadrant allow the position of the beam to be monitored for all the utilized energies. These detectors have a potential to estimate the position of the beam with a precision of about 10 μm.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  8. Performance evaluation of a depth-of-interaction detector by use of position-sensitive PMT with a super-bialkali photocathode.

    PubMed

    Hirano, Yoshiyuki; Nitta, Munetaka; Inadama, Naoko; Nishikido, Fumihiko; Yoshida, Eiji; Murayama, Hideo; Yamaya, Taiga

    2014-01-01

    Our purpose in this work was to evaluate the performance of a 4-layer depth-of-interaction (DOI) detector composed of GSO crystals by use of a position-sensitive photomultiplier tube (PMT) with a super-bialkali photocathode (SBA) by comparing it with a standard bialkali photocathode (BA) regarding the ability to identify the scintillating crystals, energy resolution, and timing resolution. The 4-layer DOI detector was composed of a 16 × 16 array of 2.9 × 2.9 × 7.5 mm(3) GSO crystals for each layer and an 8 × 8 multi-anode array type position-sensitive PMT. The DOI was achieved by a reflector control method, and the Anger method was used for calculating interacting points. The energy resolution in full width at half-maximum (FWHM) at 511 keV energy for the top layer (the farthest from the PMT) was improved and was 12.0% for the SBA compared with the energy resolution of 12.7% for the BA. As indicators of crystal identification ability, the peak-to-valley ratio and distance-to-width ratio were calculated; the latter was defined as the average of the distance between peaks per the average of the peak width. For both metrics, improvement of several percent was obtained; for example, the peak-to-valley ratio was increased from 1.78 (BA) to 1.86 (SBA), and the distance-to-width ratio was increased from 1.47 (BA) to 1.57 (SBA). The timing resolution (FWHM) in the bottom layer was improved slightly and was 2.4 ns (SBA) compared with 2.5 ns (BA). Better performance of the DOI detector is expected by use of a super bialkali photocathode.

  9. Comparisons of LET distributions measured in low-earth orbit using tissue-equivalent proportional counters and the position-sensitive silicon-detector telescope (RRMD-III).

    PubMed

    Doke, T; Hayashi, T; Borak, T B

    2001-09-01

    Determinations of the LET distribution, phi(L), of charged particles within a spacecraft in low-Earth orbit have been made. One method used a cylindrical tissue-equivalent proportional counter (TEPC), with the assumption that for each measured event, lineal energy, y, is equal to LET and thus phi(L) = phi(y). The other was based on the direct measurement of LETs for individual particles using a charged-particle telescope consisting of position-sensitive silicon detectors called RRMD-III. There were differences of up to a factor of 10 between estimates of phi(L) using the two methods on the same mission. This caused estimates of quality factor to vary by a factor of two between the two methods.

  10. De-Li-DAQ-2D - a new data acquisition system for position-sensitive neutron detectors with delay-line readout

    NASA Astrophysics Data System (ADS)

    Levchanovskiy, F. V.; Murashkevich, S. M.

    2016-09-01

    Software for a data acquisition system of modern one- and two-dimensional position-sensitive detectors with delay-line readout, which includes a software interface to a new electronic module De-Li-DAQ-2D with a USB interface, is presented. The new system after successful tests on the stand and on several spectrometers of the IBR-2 reactor has been integrated into the software complex SONIX+ [1]. The De-Li- DAQ-2D module [2] contains an 8-channel time-code converter (TDC-GPX) with a time resolution of 80 ps, field programmable gate array (FPGA), 1 Gbyte histogram memory and high-speed interface with a fiber-optic communication line. A real count rate is no less than 106 events/s. The De-Li-DAQ-2D module is implemented in the NIM standard. The De-Li-DAQ-2D module can operate in two modes: histogram mode and list mode.

  11. Influence of temperature and bias voltage on the performance of a high resolution PET detector built with position sensitive avalanche photodiodes

    NASA Astrophysics Data System (ADS)

    Vandenbroucke, A.; McLaughlin, T. J.; Levin, C. S.

    2012-08-01

    We evaluate the performance of an 8 × 8 array of 0.9 × 0.9 × 1 mm3 cerium doped lutetium oxyothosilicate (LSO) crystals coupled to a position sensitive avalanche photodiode (PSAPD) as a function of bias voltage and temperature. We use this detector to develop a general methodology to optimize bias voltage, temperature, and gain for PET detectors using semiconductor photodetectors. This detector module will be used in a novel high resolution positron emission tomography (PET) camera dedicated to breast imaging under construction in our lab. Due to the tight packing of many PSAPDs in the system a thermal gradient is expected across the imaging heads. Data were collected for 11 PSAPD temperatures between 5°C and 40°C using a thermo-electric (Peltier) device. At each temperature the bias voltage was varied in steps of 5 V over a 50 V range. We present three methods to predict the optimal bias voltage at every temperature: one based on optimizing the coincidence time resolution, the others based on the relative change in PSAPD gain and leakage current due to the onset of hole multiplication. Optimal gain could also be predicted based on the quality of the flood histogram. At optimal bias voltage, the energy resolution degrades as (10.5±0.1)+((0.038±0.006)/ °C·T)%. Time resolution stays constant at 2.37±0.02 ns below 15°C. Above this temperature, time resolution deteriorates as (1.67±0.06)+((0.042±0.002)/°C·T)ns. Even at high temperatures, all 64 crystal position peaks in the flood histogram are still clearly visible. The width of the peaks in the flood histogram show a quadratic degradation with temperature: (2.6±0.1)·10-2+(1.6±0.2)·10-5/(°C)2·T2. We conclude that both the quality of the flood histogram as well as the coincidence time resolution are better parameters to estimate the optimal bias voltage, than energy resolution. Optimal bias voltage is found to be dependent on the value of k, the ratio between hole and electron multiplication. We

  12. Position Sensitive Microcalorimeters

    NASA Technical Reports Server (NTRS)

    Sadleir, J. E.; Hammock, C.; Figueroa-Feliciano, E.; Stahle, C. K.; Bandler, S.; Saab, T.; Lindeman, M.; Porter, F. S.; Chervenak, J.; Brown, G.

    2004-01-01

    A Position Sensitive Transition-Edge Sensor (PoST) is a microcalorimeter device capable of one-dimensional imaging spectroscopy. The device consists of two Transition-Edge Sensors (TESs) connected to the ends of a long X-ray absorbing strip. The energy of a photon hitting the absorber and the position of the absorption event along the strip is measured from the response in the two sensors by analyzing the relative signal sizes, pulse rise times, and the sum of the pulses measured at each sensor, We report on the recent PoST effort at Goddard for applications to large field of view, high-energy- resolution, X-ray astrophysics.

  13. Position-sensitive detector system OBI for High Resolution X-Ray Powder Diffraction using on-site readable image plates

    NASA Astrophysics Data System (ADS)

    Knapp, M.; Joco, V.; Baehtz, C.; Brecht, H. H.; Berghaeuser, A.; Ehrenberg, H.; von Seggern, H.; Fuess, H.

    2004-04-01

    A one-dimensional detector system has been developed using image plates. The detector is working in transmission mode or Debye-Scherrer geometry and is on-site readable which reduces the effort for calibration. It covers a wide angular range up to 110° and shows narrow reflection half-widths depending on the capillary diameter. The acquisition time is in the range of minutes and the data quality allows for reliable Rietveld refinement of complicated structures, even in multi-phase samples. The detector opens a wide field of new applications in kinetics and temperature resolved measurements.

  14. Linear, position-sensitive x-ray detector used for real-time calculations of small-angle scattering parameters with submillisecond resolution

    SciTech Connect

    Borso, C.S.

    1984-01-01

    The advent of high-intensity X-ray synchrotron sources has made possible the measurement of fluctuations in small-angle scattering parameters from typical specimens on a submillisecond time scale in real-time. The fundamental design of any fast detector system optimized for such measurements will incorporate some type of solid state detector array capable of rapid encoding algorithms. A prototype with a self-scanning photodiode array has been designed and tested at beamline 1 to 4 at the Stanford Synchrotron Radiation Laboratory (SSRL), and the results indicate that the device will operate at speeds yielding submillisecond temporal resolution in real-time.

  15. An array of virtual Frisch-grid CdZnTe detectors and a front-end application-specific integrated circuit for large-area position-sensitive gamma-ray cameras

    SciTech Connect

    Bolotnikov, A. E.; Ackley, K.; Camarda, G. S.; Cherches, C.; Cui, Y.; De Geronimo, G.; Fried, J.; Hodges, D.; Hossain, A.; Lee, W.; Mahler, G.; Maritato, M.; Petryk, M.; Roy, U.; Salwen, C.; Vernon, E.; Yang, G.; James, R. B.

    2015-07-28

    We developed a robust and low-cost array of virtual Frisch-grid CdZnTe (CZT) detectors coupled to a front-end readout ASIC for spectroscopy and imaging of gamma rays. The array operates as a self-reliant detector module. It is comprised of 36 close-packed 6x6x15 mm3 detectors grouped into 3x3 sub-arrays of 2x2 detectors with the common cathodes. The front-end analog ASIC accommodates up to 36 anode and 9 cathode inputs. Several detector modules can be integrated into a single- or multi-layer unit operating as a Compton or a coded-aperture camera. We present the results from testing two fully assembled modules and readout electronics. The further enhancement of the arrays’ performance and reduction of their cost are made possible by using position-sensitive virtual Frisch-grid detectors, which allow for accurate corrections of the response of material non-uniformities caused by crystal defects.

  16. An array of virtual Frisch-grid CdZnTe detectors and a front-end application-specific integrated circuit for large-area position-sensitive gamma-ray cameras

    DOE PAGES

    Bolotnikov, A. E.; Ackley, K.; Camarda, G. S.; ...

    2015-07-28

    We developed a robust and low-cost array of virtual Frisch-grid CdZnTe (CZT) detectors coupled to a front-end readout ASIC for spectroscopy and imaging of gamma rays. The array operates as a self-reliant detector module. It is comprised of 36 close-packed 6x6x15 mm3 detectors grouped into 3x3 sub-arrays of 2x2 detectors with the common cathodes. The front-end analog ASIC accommodates up to 36 anode and 9 cathode inputs. Several detector modules can be integrated into a single- or multi-layer unit operating as a Compton or a coded-aperture camera. We present the results from testing two fully assembled modules and readout electronics.more » The further enhancement of the arrays’ performance and reduction of their cost are made possible by using position-sensitive virtual Frisch-grid detectors, which allow for accurate corrections of the response of material non-uniformities caused by crystal defects.« less

  17. An array of virtual Frisch-grid CdZnTe detectors and a front-end application-specific integrated circuit for large-area position-sensitive gamma-ray cameras.

    PubMed

    Bolotnikov, A E; Ackley, K; Camarda, G S; Cherches, C; Cui, Y; De Geronimo, G; Fried, J; Hodges, D; Hossain, A; Lee, W; Mahler, G; Maritato, M; Petryk, M; Roy, U; Salwen, C; Vernon, E; Yang, G; James, R B

    2015-07-01

    We developed a robust and low-cost array of virtual Frisch-grid CdZnTe detectors coupled to a front-end readout application-specific integrated circuit (ASIC) for spectroscopy and imaging of gamma rays. The array operates as a self-reliant detector module. It is comprised of 36 close-packed 6 × 6 × 15 mm(3) detectors grouped into 3 × 3 sub-arrays of 2 × 2 detectors with the common cathodes. The front-end analog ASIC accommodates up to 36 anode and 9 cathode inputs. Several detector modules can be integrated into a single- or multi-layer unit operating as a Compton or a coded-aperture camera. We present the results from testing two fully assembled modules and readout electronics. The further enhancement of the arrays' performance and reduction of their cost are possible by using position-sensitive virtual Frisch-grid detectors, which allow for accurate corrections of the response of material non-uniformities caused by crystal defects.

  18. An array of virtual Frisch-grid CdZnTe detectors and a front-end application-specific integrated circuit for large-area position-sensitive gamma-ray cameras

    SciTech Connect

    Bolotnikov, A. E. Ackley, K.; Camarda, G. S.; Cherches, C.; Cui, Y.; De Geronimo, G.; Fried, J.; Hossain, A.; Mahler, G.; Maritato, M.; Roy, U.; Salwen, C.; Vernon, E.; Yang, G.; James, R. B.; Hodges, D.; Lee, W.; Petryk, M.

    2015-07-15

    We developed a robust and low-cost array of virtual Frisch-grid CdZnTe detectors coupled to a front-end readout application-specific integrated circuit (ASIC) for spectroscopy and imaging of gamma rays. The array operates as a self-reliant detector module. It is comprised of 36 close-packed 6 × 6 × 15 mm{sup 3} detectors grouped into 3 × 3 sub-arrays of 2 × 2 detectors with the common cathodes. The front-end analog ASIC accommodates up to 36 anode and 9 cathode inputs. Several detector modules can be integrated into a single- or multi-layer unit operating as a Compton or a coded-aperture camera. We present the results from testing two fully assembled modules and readout electronics. The further enhancement of the arrays’ performance and reduction of their cost are possible by using position-sensitive virtual Frisch-grid detectors, which allow for accurate corrections of the response of material non-uniformities caused by crystal defects.

  19. Count rate studies of a box-shaped PET breast imaging system comprised of position sensitive avalanche photodiodes utilizing monte carlo simulation.

    PubMed

    Foudray, Angela M K; Habte, Frezghi; Chinn, Garry; Zhang, Jin; Levin, Craig S

    2006-01-01

    We are investigating a high-sensitivity, high-resolution positron emission tomography (PET) system for clinical use in the detection, diagnosis and staging of breast cancer. Using conventional figures of merit, design parameters were evaluated for count rate performance, module dead time, and construction complexity. The detector system modeled comprises extremely thin position-sensitive avalanche photodiodes coupled to lutetium oxy-orthosilicate scintillation crystals. Previous investigations of detector geometries with Monte Carlo indicated that one of the largest impacts on sensitivity is local scintillation crystal density when considering systems having the same average scintillation crystal densities (same crystal packing fraction and system solid-angle coverage). Our results show the system has very good scatter and randoms rejection at clinical activity ranges ( approximately 200 muCi).

  20. Breakup of loosely bound nuclei at intermediate energies for nuclear astrophysics and the development of a position sensitive microstrip detector system and its readout electronics using ASICs technologies

    SciTech Connect

    Bertulani, Carlos A.

    2016-01-12

    The work performed under this grant has led to the development of a detection system that will be used to measure reaction rates for proton or neutron capture reactions at stellar energies on radioactive ions far from stability. The reaction rates are needed to better understand the physics of nucleosynthesis in explosive stellar processes such as supernovae and x-ray burst events. The radioactive ions will be produced at the Radioactive Ion Beam Facility (RIBF) at RIKEN near Tokyo, Japan. During the course of this work, the group involved in this project has expanded by several institutions in Europe and Japan and now involves collaborators from the U.S., Japan, Hungary, Romania, Germany, Spain, Italy, China, and South Korea. As part of the project, a novel design based on large-area silicon detectors has been built and tested. The work has involved mechanical construction of a special purpose vacuum chamber, with a precision mounting system for the silicon detectors, development of a new ASICs readout system that has applications with a wide variety of silicon detector systems, and the development of a data acquisition system that is integrated into the computer system being used at RIBF. The parts noted above that are needed to carry out the research program are completed and ready for installation. Several approved experiments that will use this system will be carried out in the near future. The experimental work has been delayed due to a large increase in the cost and availability of electrical power for RIBF that occurred following the massive earthquake and tsunami that hit Japan in the spring of 2011. Another component of the research carried out with this grant involved developing the theoretical tools that are required to extract the information from the experiments that is needed to determine the stellar reaction rates. The tools developed through this part of the work will be made freely available for general use.

  1. Breakup of loosely bound nuclei at intermediate energies for nuclear astrophysics and the development of a position sensitive microstrip detector system and its readout electronics using ASICs technologies

    SciTech Connect

    Tribble, Robert E.; Sobotka, Lee G.; Blackmon, Jeff C.; Bertulani, Carlos A.

    2015-12-29

    The work performed under this grant has led to the development of a detection system that will be used to measure reaction rates for proton or neutron capture reactions at stellar energies on radioactive ions far from stability. The reaction rates are needed to better understand the physics of nucleosynthesis in explosive stellar processes such as supernovae and x-ray burst events. The radioactive ions will be produced at the Radioactive Ion Beam Facility (RIBF) at RIKEN near Tokyo, Japan. During the course of this work, the group involved in this project has expanded by several institutions in Europe and Japan and now involves collaborators from the U.S., Japan, Hungary, Romania, Germany, Spain, Italy, China, and South Korea. As part of the project, a novel design based on large-area silicon detectors has been built and tested and the performance characterized in a series of tests using particle beams with a variety of atomic numbers at the Cyclotron Institute of Texas A&M University and the Heavy Ion Medical Accelerator in Chiba facility (HIMAC) in Chiba, Japan. The work has involved mechanical construction of a special purpose vacuum chamber, with a precision mounting system for the silicon detectors, development of a new ASICs readout system that has applications with a wide variety of silicon detector systems, and the development of a data acquisition system that is integrated into the computer system being used at RIBF. The parts noted above that are needed to carry out the research program are completed and ready for installation. Several approved experiments that will use this system will be carried out in the near future. The experimental work has been delayed due to a large increase in the cost and availability of electrical power for RIBF that occurred following the massive earthquake and tsunami that hit Japan in the spring of 2011. Another component of the research carried out with this grant involved developing the theoretical tools that are required

  2. High Dynamics and Precision Optical Measurement Using a Position Sensitive Detector (PSD) in Reflection-Mode: Application to 2D Object Tracking over a Smart Surface

    PubMed Central

    Ivan, Ioan Alexandru; Ardeleanu, Mihai; Laurent, Guillaume J.

    2012-01-01

    When related to a single and good contrast object or a laser spot, position sensing, or sensitive, detectors (PSDs) have a series of advantages over the classical camera sensors, including a good positioning accuracy for a fast response time and very simple signal conditioning circuits. To test the performance of this kind of sensor for microrobotics, we have made a comparative analysis between a precise but slow video camera and a custom-made fast PSD system applied to the tracking of a diffuse-reflectivity object transported by a pneumatic microconveyor called Smart-Surface. Until now, the fast system dynamics prevented the full control of the smart surface by visual servoing, unless using a very expensive high frame rate camera. We have built and tested a custom and low cost PSD-based embedded circuit, optically connected with a camera to a single objective by means of a beam splitter. A stroboscopic light source enhanced the resolution. The obtained results showed a good linearity and a fast (over 500 frames per second) response time which will enable future closed-loop control by using PSD. PMID:23223078

  3. High dynamics and precision optical measurement using a position sensitive detector (PSD) in reflection-mode: application to 2D object tracking over a Smart Surface.

    PubMed

    Ivan, Ioan Alexandru; Ardeleanu, Mihai; Laurent, Guillaume J

    2012-12-06

    When related to a single and good contrast object or a laser spot, position sensing, or sensitive, detectors (PSDs) have a series of advantages over the classical camera sensors, including a good positioning accuracy for a fast response time and very simple signal conditioning circuits. To test the performance of this kind of sensor for microrobotics, we have made a comparative analysis between a precise but slow video camera and a custom-made fast PSD system applied to the tracking of a diffuse-reflectivity object transported by a pneumatic microconveyor called Smart-Surface. Until now, the fast system dynamics prevented the full control of the smart surface by visual servoing, unless using a very expensive high frame rate camera. We have built and tested a custom and low cost PSD-based embedded circuit, optically connected with a camera to a single objective by means of a beam splitter. A stroboscopic light source enhanced the resolution. The obtained results showed a good linearity and a fast (over 500 frames per second) response time which will enable future closed-loop control by using PSD.

  4. A position-sensitive twin ionization chamber for fission fragment and prompt neutron correlation experiments

    NASA Astrophysics Data System (ADS)

    Göök, A.; Geerts, W.; Hambsch, F.-J.; Oberstedt, S.; Vidali, M.; Zeynalov, Sh.

    2016-09-01

    A twin position-sensitive Frisch grid ionization chamber, intended as a fission fragment detector in experiments to study prompt fission neutron correlations with fission fragment properties, is presented. Fission fragment mass and energies are determined by means of the double kinetic energy technique, based on conservation of mass and linear momentum. The position sensitivity is achieved by replacing each anode plate in the standard twin ionization chamber by a wire plane and a strip anode, both readout by means of resistive charge division. This provides information about the fission axis orientation, which is necessary to reconstruct the neutron emission process in the fully accelerated fragment rest-frame. The energy resolution compared to the standard twin ionization chamber is found not to be affected by the modification. The angular resolution of the detector relative to an arbitrarily oriented axis is better than 7° FWHM. Results on prompt fission neutron angular distributions in 235U(n,f) obtained with the detector in combination with an array of neutron scintillation detectors is presented as a proof of principle.

  5. Dual Position Sensitive MWPC for tracking reaction products at VAMOS++

    NASA Astrophysics Data System (ADS)

    Vandebrouck, M.; Lemasson, A.; Rejmund, M.; Fremont, G.; Pancin, J.; Navin, A.; Michelagnoli, C.; Goupil, J.; Spitaels, C.; Jacquot, B.

    2016-03-01

    The characteristics and performance of a Dual Position Sensitive Multi-Wire Proportional Counter (DPS-MWPC) used to measure the scattering angle, the interaction position on the target and the velocity of reaction products detected in the VAMOS++ magnetic spectrometer, are reported. The detector consists of a pair of position sensitive low pressure MWPCs and provides both fast timing signals, along with the two-dimensional position coordinates required to define the trajectory of the reaction products. A time-of-flight resolution of 305(11) ps (FWHM) was measured. The measured resolutions (FWHM) were 2.5(3) mrad and 560(70) μm for the scattering angle and the interaction point at the target respectively. The subsequent improvement of the Doppler correction of the energy of the γ-rays, detected in the γ-ray tracking array AGATA in coincidence with isotopically identified ions in VAMOS++, is also discussed.

  6. Position-sensitive scanning fluorescence correlation spectroscopy.

    PubMed

    Skinner, Joseph P; Chen, Yan; Müller, Joachim D

    2005-08-01

    Fluorescence correlation spectroscopy (FCS) uses a stationary laser beam to illuminate a small sample volume and analyze the temporal behavior of the fluorescence fluctuations within the stationary observation volume. In contrast, scanning FCS (SFCS) collects the fluorescence signal from a moving observation volume by scanning the laser beam. The fluctuations now contain both temporal and spatial information about the sample. To access the spatial information we synchronize scanning and data acquisition. Synchronization allows us to evaluate correlations for every position along the scanned trajectory. We use a circular scan trajectory in this study. Because the scan radius is constant, the phase angle is sufficient to characterize the position of the beam. We introduce position-sensitive SFCS (PSFCS), where correlations are calculated as a function of lag time and phase. We present the theory of PSFCS and derive expressions for diffusion, diffusion in the presence of flow, and for immobilization. To test PSFCS we compare experimental data with theory. We determine the direction and speed of a flowing dye solution and the position of an immobilized particle. To demonstrate the feasibility of the technique for applications in living cells we present data of enhanced green fluorescent protein measured in the nucleus of COS cells.

  7. A position sensitive microchannel photomultiplier for ultraviolet space astronomy

    NASA Technical Reports Server (NTRS)

    Lampton, M.; Siegmund, O. H. W.; Bixler, J.; Bowyer, S.

    1986-01-01

    The 25-mm microchannel-plate, position-sensitive UV astronomy photomultiplier tube presented is intended for the EOM-1 Spacelab Mission's FAUST payload and conducts wide-field imaging surveys in the VUV over the 1400-1800-A range. The sealed detector encompasses a CsI photocathode deposited on the inner surface of a MgF2 window, a stack of microchannel plates, and a wedge-and-strip two-dimensional position-sensing anode. Since the wedge-and-strip principle requires only three anode signals, flight electronics can be reduced to three charge amplifiers and three analog-to-digital converters.

  8. A position sensitive microchannel photomultiplier for ultraviolet space astronomy

    NASA Technical Reports Server (NTRS)

    Lampton, M.; Siegmund, O. H. W.; Bixler, J.; Bowyer, S.

    1986-01-01

    The 25-mm microchannel-plate, position-sensitive UV astronomy photomultiplier tube presented is intended for the EOM-1 Spacelab Mission's FAUST payload and conducts wide-field imaging surveys in the VUV over the 1400-1800-A range. The sealed detector encompasses a CsI photocathode deposited on the inner surface of a MgF2 window, a stack of microchannel plates, and a wedge-and-strip two-dimensional position-sensing anode. Since the wedge-and-strip principle requires only three anode signals, flight electronics can be reduced to three charge amplifiers and three analog-to-digital converters.

  9. Passive environmental radon detector study

    SciTech Connect

    Not Available

    1992-03-01

    There are three stages at which the ambient air concentrations of radon-222 are monitored around the Uranium Mill Tailings Remedial Action (UMTRA) Project sites: before, during, and after construction. Pre-remedial-action measurements are taken for approximately 1 year. Monitoring is conducted during the entire duration of construction, and post-remedial-action monitoring is performed for approximately 1 year. Currently, the UMTRA Project uses Radtrak{reg_sign} brand alpha-track radon detectors for these environmental measurements. The purposes of radon monitoring around the UMTRA sites are (1) to determine background values around the site and pre-remedial-action conditions, (2) to control construction activities and monitor off-site releases, and (3) to compare post-remedial-action concentrations with pre-remedial-action values to demonstrate that radon concentrations have been reduced to approximately background levels. The Technical Assistance Contractor to the DOE for the UMTRA Project evaluated the performance of four different types of passive environmental radon detectors under both controlled laboratory conditions and field conditions at an unremediated UMTRA site. This study was undertaken to evaluate the accuracy and precision of four different passive, timeintegrating, environmental radon detectors in an effort to determine which brand of detector is best suited to measure environmental outdoor radon concentrations for the UMTRA Project. Voluntary manufacturer participation in the study was solicited by placing an advertisement in the Commerce Business Daily. All manufacturers participating in the study supplied the detectors and analysis free of charge.

  10. Passive environmental radon detector study

    SciTech Connect

    Not Available

    1992-03-01

    There are three stages at which the ambient air concentrations of radon-222 are monitored around the Uranium Mill Tailings Remedial Action (UMTRA) Project sites: before, during, and after construction. Pre-remedial-action measurements are taken for approximately 1 year. Monitoring is conducted during the entire duration of construction, and post-remedial-action monitoring is performed for approximately 1 year. Currently, the UMTRA Project uses Radtrak[reg sign] brand alpha-track radon detectors for these environmental measurements. The purposes of radon monitoring around the UMTRA sites are (1) to determine background values around the site and pre-remedial-action conditions, (2) to control construction activities and monitor off-site releases, and (3) to compare post-remedial-action concentrations with pre-remedial-action values to demonstrate that radon concentrations have been reduced to approximately background levels. The Technical Assistance Contractor to the DOE for the UMTRA Project evaluated the performance of four different types of passive environmental radon detectors under both controlled laboratory conditions and field conditions at an unremediated UMTRA site. This study was undertaken to evaluate the accuracy and precision of four different passive, timeintegrating, environmental radon detectors in an effort to determine which brand of detector is best suited to measure environmental outdoor radon concentrations for the UMTRA Project. Voluntary manufacturer participation in the study was solicited by placing an advertisement in the Commerce Business Daily. All manufacturers participating in the study supplied the detectors and analysis free of charge.

  11. Particle tracking with scintillating fibers and position sensitive photomultipliers

    SciTech Connect

    C.F. Perdrisat; R. Pourang; D. Koechner; D. Raine, III; B. Kross; S. Majewski; A. Weisenberger; R. Wojcik; K. Zorn; V. Punjabi; A. Day

    1991-11-01

    The use of position-sensitive phototubes in conjunction with scintillating plastic fibers for a particle tracking application in a future focal plane polarimeter (FPP) in the hadron arm of the hall A HRS 2 facility at the Continuous Electron Beam Accelerator Facility (CEBAF). Current results indicate that the design parameters of the FPP in the hadron arm of the double spectrometer facility HRS2 can be met with a design which couples round or square fibers 3 mm in size to Hamamatsu R4135 phototubes. Position resolutions {sigma}x or {sigma}y on the order of 0.6 mm are obtained in the phototubes. Detector structures with staggered double fiber layers lead to overall resolution of {sigma}=1 mm, and detection efficiencies close to 1. The characteristic speed of these detectors makes them particularly appropriate for the high rates which are expected with the 200-{micro}A continuous wave beam at CEBAF.

  12. Position Sensitive Detection System for Charged Particles

    SciTech Connect

    Coello, E. A.; Favela, F.; Curiel, Q.; Chavez, E; Huerta, A.; Varela, A.; Shapira, Dan

    2012-01-01

    The position sensitive detection system presented in this work employs the Anger logic algorithm to determine the position of the light spark produced by the passage of charged particles on a 170 x 170 x 10 mm3 scintillator material (PILOT-U). The detection system consists of a matrix of nine photomultipliers, covering a fraction of the back area of the scintillators. Tests made with a non-collimated alpha particle source together with a Monte Carlo simulation that reproduces the data, suggest an intrinsic position resolution of up to 6 mm is achieved.

  13. Comparative study of silicon detectors

    SciTech Connect

    Allier, C.P.; Valk, H.; Huizenga, J.; Bom, V.R.; Hollander, R.W.; Eijk, C.W.E. van

    1998-06-01

    The authors studied three different types of silicon sensors: PIN diodes, circular drift detectors, both made at the Delft University of Technology (DUT), and Hamamatsu S5345 avalanche photodiodes. Measurements have been carried out in the same optimized experimental setup, both at room temperature and at low temperatures. Comparison is made for direct X-ray detection and CsI(Tl) scintillation light readout.

  14. Theoretical Noise Analysis on a Position-sensitive Metallic Magnetic Calorimeter

    NASA Technical Reports Server (NTRS)

    Smith, Stephen J.

    2007-01-01

    We report on the theoretical noise analysis for a position-sensitive Metallic Magnetic Calorimeter (MMC), consisting of MMC read-out at both ends of a large X-ray absorber. Such devices are under consideration as alternatives to other cryogenic technologies for future X-ray astronomy missions. We use a finite-element model (FEM) to numerically calculate the signal and noise response at the detector outputs and investigate the correlations between the noise measured at each MMC coupled by the absorber. We then calculate, using the optimal filter concept, the theoretical energy and position resolution across the detector and discuss the trade-offs involved in optimizing the detector design for energy resolution, position resolution and count rate. The results show, theoretically, the position-sensitive MMC concept offers impressive spectral and spatial resolving capabilities compared to pixel arrays and similar position-sensitive cryogenic technologies using Transition Edge Sensor (TES) read-out.

  15. Delay-Line Three-Dimensional Position Sensitive Radiation Detection

    NASA Astrophysics Data System (ADS)

    Jeong, Manhee

    High-resistivity silicon(Si) in large volumes and with good charge carrier transport properties has been produced and achieved success as a radiation detector material over the past few years due to its relatively low cost as well as the availability of well-established processing technologies. One application of that technology is in the fabrication of various position-sensing topologies from which the incident radiation's direction can be determined. We have succeeded in developing the modeling tools for investigating different position-sensing schemes and used those tools to examine both amplitude-based and time-based methods, an assessment that indicates that fine position-sensing can be achieved with simpler readout designs than are conventionally deployed. This realization can make ubiquitous and inexpensive deployment of special nuclear materials (SNM) detecting technology becomes more feasible because if one can deploy position-sensitive semiconductor detectors with only one or two contacts per side. For this purpose, we have described the delay-line radiation detector and its optimized fabrication. The semiconductor physics were simulated, the results from which guided the fabrication of the guard ring structure and the detector electrode, both of which included metal-field-plates. The measured improvement in the leakage current was confirmed with the fabricated devices, and the structures successfully suppressed soft-breakdown. We also demonstrated that fabricating an asymmetric strip-line structure successfully minimizing the pulse shaping and increases the distance through which one can propagate the information of the deposited charge distribution. With fabricated delay-line detectors we can acquire alpha spectra (Am-241) and gamma spectra (Ba-133, Co-57 and Cd-109). The delay-line detectors can therefore be used to extract the charge information from both ion and gamma-ray interactions. Furthermore, standard charge-sensitive circuits yield high SNR

  16. Position sensitive disc for charged particle detection

    NASA Astrophysics Data System (ADS)

    Bellini, V.; Palazzolo, F.; Scirè, A.; Sperduto, M. L.; Albergo, S.; Poli, G.; Potenza, R.; Randieri, C.; Russo, V.; Sutera, M. C.; Capogni, M.; Schaerf, C.; D'Angelo, A.; Moricciani, D.; Kuznetsov, A. V.; Girolami, B.; Ghio, F.

    2001-04-01

    A plastic scintillating disc (NE102, 3 cm thick, 1 m diameter) has been designed for detecting charged pions in nuclear reactions at intermediate energy. A hole of 20 cm diameter was made in the middle of the disc in order to allow for the beam passage through the detector. The originality of the detector consists of the simultaneous use of four very compact central Photo Multiplier Tubes (PMT) and eight peripheral PMTs in order to retrieve the hitting point of a charged particle onto the disc surface with a space resolution of ±3 cm. The original method has been developed by using polar coordinates and only the Time-Of-Flight information (TOF) from three or four nearest PMTs, including at least one central PMT.

  17. Position-sensitive coincidence detection of nuclear reaction products at the Prague Van-de-Graaff accelerator

    NASA Astrophysics Data System (ADS)

    Granja, Carlos; Kraus, Vaclav; Pugatch, Valery; Kohout, Zdenek

    2017-06-01

    In low-energy nuclear reactions of astrophysical interest or fusion studies the spatial- and time-correlated detection of two and more reaction products can be a valuable tool in studies of reaction mechanisms, resolving reaction channels and measuring angular distributions of reaction products. For this purpose we constructed a configurable array of position-sensitive detectors based on the hybrid semiconductor pixel detector Timepix. Additional analog-signal electronics provide self-trigger together with extended multi-device control and synchronized readout electronics by a customized control and coincidence unit. The instrumentation, developed and used for detection of fission fragments in spontaneous and neutron induced fission as well as in charged particle detection in neutron induced reactions, is being implemented for low-energy light-ion induced nuclear reactions. Application and demonstration of the technique with two Timepix detectors on p+p elastic scattering at the Van-de-Graaff (VdG) accelerator in Prague is given.

  18. Michrochannel plate for position sensitive alpha particle detection

    SciTech Connect

    Paul Hurley and James Tinsley

    2007-08-31

    This paper will describe the use of a microchannel plate (MCP) as the associated particle detector on a sealed tube neutron generator. The generator produces neutrons and associated alpha particles for use as a probe to locate and identify hidden explosives in associated particle imaging (API). The MCP measures the position in two dimensions and precise timing of the incident alpha particle, information which is then used to calculate the emission time and direction of the corresponding neutron. The MCP replaces the position-sensitive photomultipler tube (PSPMT) which, until recently, had been the only detector available for measuring position and timing for alpha particles in neutron generator applications. Where the PSPMT uses charge division for generating position information, a process that requires a first order correction to each pulse, the MCP uses delay-line timing, which requires no correction. The result is a device with an order of magnitude improvement in both position resolution and timing compared to the PSPMT. Hardware and software development and the measurements made to characterize the MCP for API applications are described.

  19. Practical Considerations for Optimizing Position Sensitivity in Arrays of Position-sensitive TES's

    NASA Technical Reports Server (NTRS)

    Smith, Stephen J.; Bandler, Simon R.; Figueroa-Feliciano, Encetali; Iyomoto, Naoko; Kelley, Richard L.; Kilbourne, Caroline A.; Porder, Frederick S.; Sadleir, John E.

    2007-01-01

    We are developing Position-Sensitive Transitions-Edge Sensors (PoST's) for future X-ray astronomy missions such as NASA's Constellation-X. The PoST consists of one or more Transitions Edge Sensors (TES's) thermally connected to a large X-ray absorber, which through heat diffusion, gives rise to position dependence. The development of PoST's is motivated by the desire to achieve the largest the focal-plan coverage with the fewest number of readout channels. In order to develop a practical array, consisting of an inner pixellated core with an outer array of large absorber PoST's, we must be able to simultaneously read out all (-1800) channels in the array. This is achievable using time division multiplexing (TDM), but does set stringent slew rate requirements on the array. Typically, we must damp the pulses to reduce the slew rate of the input signal to the TDM. This is achieved by applying a low-pass analog filter with large inductance to the signal. This attenuates the high frequency components of the signal, essential for position discrimination in PoST's, relative to the white noise of the readout chain and degrades the position sensitivity. Using numerically simulated data, we investigate the position sensing ability of typical PoST designs under such high inductance conditions. We investigate signal-processing techniques for optimal determination of the event position and discuss the practical considerations for real-time implementation.

  20. Practical Considerations for Optimizing Position Sensitivity in Arrays of Position-sensitive TES's

    NASA Technical Reports Server (NTRS)

    Smith, Stephen J.; Bandler, Simon R.; Figueroa-Feliciano, Encetali; Iyomoto, Naoko; Kelley, Richard L.; Kilbourne, Caroline A.; Porder, Frederick S.; Sadleir, John E.

    2007-01-01

    We are developing Position-Sensitive Transitions-Edge Sensors (PoST's) for future X-ray astronomy missions such as NASA's Constellation-X. The PoST consists of one or more Transitions Edge Sensors (TES's) thermally connected to a large X-ray absorber, which through heat diffusion, gives rise to position dependence. The development of PoST's is motivated by the desire to achieve the largest the focal-plan coverage with the fewest number of readout channels. In order to develop a practical array, consisting of an inner pixellated core with an outer array of large absorber PoST's, we must be able to simultaneously read out all (-1800) channels in the array. This is achievable using time division multiplexing (TDM), but does set stringent slew rate requirements on the array. Typically, we must damp the pulses to reduce the slew rate of the input signal to the TDM. This is achieved by applying a low-pass analog filter with large inductance to the signal. This attenuates the high frequency components of the signal, essential for position discrimination in PoST's, relative to the white noise of the readout chain and degrades the position sensitivity. Using numerically simulated data, we investigate the position sensing ability of typical PoST designs under such high inductance conditions. We investigate signal-processing techniques for optimal determination of the event position and discuss the practical considerations for real-time implementation.

  1. Signal and noise properties of position-sensitive avalanche photodiodes.

    PubMed

    Yang, Yongfeng; Wu, Yibao; Farrell, Richard; Dokhale, Purushottam A; Shah, Kanai S; Cherry, Simon R

    2011-10-07

    After many years of development, position-sensitive avalanche photodiodes (PSAPDs) are now being incorporated into a range of scintillation detector systems, including those used in high-resolution small-animal PET and PET/MR scanners. In this work, the signal, noise, signal-to-noise ratio (SNR), flood histogram and timing resolution were measured for lutetium oxyorthosilicate (LSO) scintillator arrays coupled to PSAPDs ranging in size from 10 to 20 mm, and the optimum bias voltage and working temperature were determined. Variations in the SNR performance of PSAPDs with the same dimensions were small, but the SNR decreased significantly with increasing PSAPD size and increasing temperature. Smaller PSAPDs (10 mm and 15 mm in width) produced acceptable flood histograms at 24 °C, and cooling lower than 16 °C produced little improvement. The optimum bias voltage was about 25 V below the break down voltage. The larger 20 mm PSAPDs have lower SNR and require cooling to 0-7 °C for acceptable performance. The optimum bias voltage is also lower (35 V or more below the break down voltage depending on the temperature). Significant changes in the timing resolution were observed as the bias voltage and temperature varied. Higher bias voltages provided better timing resolution. The best timing resolution obtained for individual crystals was 2.8 ns and 3.3 ns for the 10 mm and 15 mm PSAPDs, respectively. The results of this work provide useful guidance for selecting the bias voltage and working temperature for scintillation detectors that incorporate PSAPDs as the photodetector.

  2. Signal and Noise Properties of Position-Sensitive Avalanche Photodiodes

    PubMed Central

    Yang, Yongfeng; Wu, Yibao; Farrell, Richard; Dokhale, Purushottam A.; Shah, Kanai S.; Cherry, Simon R.

    2011-01-01

    After many years of development, position-sensitive avalanche photodiodes (PSAPDs) are now being incorporated into a range of scintillation detector systems, including those used in high-resolution small-animal PET and PET/MR scanners. In this work, the signal, noise, signal-to-noise ratio (SNR), flood histogram and timing resolution were measured for lutetium oxyorthosilicate (LSO) scintillator arrays coupled to PSAPDs ranging in size from 10–20 mm, and the optimum bias voltage and working temperature determined. Variations in the SNR performance of PSAPDs with the same dimensions were small, but the SNR decreased significantly with increasing PSAPD size and increasing temperature. Smaller PSAPDs (10 mm and 15 mm in width) produced acceptable flood histograms at 24 °C, and cooling lower than 16 °C produced little improvement. The optimum bias voltage was about 25 V below the break down voltage. The larger 20 mm PSAPDs have lower SNR and require cooling to 0–7 °C for acceptable performance. The optimum bias voltage also is lower (35 V or more below the break down voltage depending on the temperature). Significant changes in the timing resolution were observed as the bias voltage and temperature were varied. Higher bias voltages provided better timing resolution. The best timing resolution obtained for individual crystals was 2.8 ns and 3.3 ns for the 10 mm and 15 mm PSAPDs, respectively. The results of this work provide useful guidance for selecting the bias voltage and working temperature for scintillation detectors that incorporate PSAPDs as the photodetector. PMID:21896961

  3. Monte Carlo studies of ARA detector optimization

    NASA Astrophysics Data System (ADS)

    Stockham, Jessica

    2013-04-01

    The Askaryan Radio Array (ARA) is a neutrino detector deployed in the Antarctic ice sheet near the South Pole. The array is designed to detect ultra high energy neutrinos in the range of 0.1-10 EeV. Detector optimization is studied using Monte Carlo simulations.

  4. Development of Three-Dimensional Position-Sensitive Room Temperature Semiconductor Gamma-Ray Spectrometers

    SciTech Connect

    Zhong He; Wen Li; Glenn F. Knoll; D. K. Wehe

    2000-06-04

    Semiconductor detectors can provide better spectroscopic performance than scintillation or gas-filled detectors because of the small ionization energy required to generate each electron-hole pair. Indeed, cryogenically cooled high-purity germanium detectors have played the dominant role whenever the best gamma-ray spectroscopy is required. A decades-long search for other semiconductor detectors that could provide higher stopping power and could operate at room temperature has been ongoing. Wide-bandgap semiconductors, such as CdTe, CdZnTe, and HgI{sub 2}, have captured the most attention. However, the use of these semiconductors in detectors has been hindered primarily by problems of charge trapping and material nonuniformity. Introduced in 1994, single-polarity charge sensing on semiconductor detectors has shown great promise in avoiding the hole-trapping problem, and the newly demonstrated three-dimensional position-sensing technique can significantly mitigate the degradation of energy resolution due to nonuniformity of detector material. In addition, three-dimensional position sensitivity will provide unique imaging capabilities of these gamma-ray spectrometers. These devices are of interest for nuclear nonproliferation, medical imaging, gamma-ray astronomy, and high-energy physics applications. This paper describes the three-dimensional position-sensing method and reports our latest results using second-generation three-dimensional position-sensitive semiconductor spectrometers.

  5. 43 CFR 422.11 - Position sensitivity and investigations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 1 2012-10-01 2011-10-01 true Position sensitivity and investigations. 422.11 Section 422.11 Public Lands: Interior Regulations Relating to Public Lands BUREAU OF... Requirements § 422.11 Position sensitivity and investigations. Each law enforcement contract or cooperative...

  6. 43 CFR 422.11 - Position sensitivity and investigations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 43 Public Lands: Interior 1 2014-10-01 2014-10-01 false Position sensitivity and investigations. 422.11 Section 422.11 Public Lands: Interior Regulations Relating to Public Lands BUREAU OF... Requirements § 422.11 Position sensitivity and investigations. Each law enforcement contract or cooperative...

  7. 43 CFR 422.11 - Position sensitivity and investigations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Position sensitivity and investigations. 422.11 Section 422.11 Public Lands: Interior Regulations Relating to Public Lands BUREAU OF... Requirements § 422.11 Position sensitivity and investigations. Each law enforcement contract or cooperative...

  8. 43 CFR 422.11 - Position sensitivity and investigations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 1 2013-10-01 2013-10-01 false Position sensitivity and investigations. 422.11 Section 422.11 Public Lands: Interior Regulations Relating to Public Lands BUREAU OF... Requirements § 422.11 Position sensitivity and investigations. Each law enforcement contract or cooperative...

  9. 43 CFR 422.11 - Position sensitivity and investigations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Position sensitivity and investigations. 422.11 Section 422.11 Public Lands: Interior Regulations Relating to Public Lands BUREAU OF... Requirements § 422.11 Position sensitivity and investigations. Each law enforcement contract or cooperative...

  10. Functionalised hexagonal-domain graphene for position-sensitive photodetectors

    NASA Astrophysics Data System (ADS)

    De Sanctis, Adolfo; Barnes, Matthew D.; Amit, Iddo; Craciun, Monica F.; Russo, Saverio

    2017-03-01

    Graphene’s unique photoresponse has been largely used in a multitude of optoelectronics applications ranging from broadband photodetectors to wave-guide modulators. In this work we extend the range of applications to position-sensitive photodetectors (PSDs) using FeCl3-intercalated hexagonal domains of graphene grown by atmospheric pressure chemical vapour deposition (APCVD). The FeCl3-based chemical functionalisation of APCVD graphene crystals is affected by the presence of wrinkles and results in a non-uniform doping of the graphene layers. This doping profile creates multiple p-p+ photoactive junctions which show a linear and bipolar photoresponse with respect to the position of a focused light spot, which is ideal for the realization of a PSD. Our study paves the way towards the fabrication of flexible and transparent PSDs that could be embedded in smart textile and wearable electronics.

  11. Functionalised hexagonal-domain graphene for position-sensitive photodetectors.

    PubMed

    De Sanctis, Adolfo; Barnes, Matthew D; Amit, Iddo; Craciun, Monica F; Russo, Saverio

    2017-03-24

    Graphene's unique photoresponse has been largely used in a multitude of optoelectronics applications ranging from broadband photodetectors to wave-guide modulators. In this work we extend the range of applications to position-sensitive photodetectors (PSDs) using FeCl3-intercalated hexagonal domains of graphene grown by atmospheric pressure chemical vapour deposition (APCVD). The FeCl3-based chemical functionalisation of APCVD graphene crystals is affected by the presence of wrinkles and results in a non-uniform doping of the graphene layers. This doping profile creates multiple p-p(+) photoactive junctions which show a linear and bipolar photoresponse with respect to the position of a focused light spot, which is ideal for the realization of a PSD. Our study paves the way towards the fabrication of flexible and transparent PSDs that could be embedded in smart textile and wearable electronics.

  12. Theory and development of position-sensitive quantum calorimeters

    NASA Astrophysics Data System (ADS)

    Figueroa Feliciano, Enectali

    Quantum calorimeters are being developed as imaging spectrometers for future X-ray astrophysics observatories. Much of the science to be done by these instruments could benefit greatly from larger focal-plane coverage of the detector (without increasing pixel size). An order of magnitude more area will greatly increase the science throughput of these future instruments. One of the main deterrents to achieving this goal is the complexity of the readout schemes involved. We devised a way to increase the number of pixels from the current baseline designs by an order of magnitude without increasing the number of channels required for readout. The instrument is a high energy resolution, distributed-readout imaging spectrometer called a Position-Sensitive Transition-Edge Sensor (PoST). A PoST is a quantum calorimeter consisting of two Transition-Edge Sensors (TESs) on the ends of a long absorber to do one-dimensional imaging spectroscopy. Comparing rise time and energy information, the position of the event in the PoST is determined. Energy is inferred from the sum of the two pulses. We develop a generalized theoretical formalism for distributed-readout calorimeters and apply it to our devices. We derive the noise theory and calculate the theoretical energy resolution of a PoST. Our calculations show that a 7-pixel PoST with 6˜keV saturation energy can achieve 2.3˜eV resolution, making this a competitive design for future quantum calorimeter instruments. For this thesis we fabricated 7- and 15-pixel PoSTs using Mo/Au TESs and gold absorbers, and moved from concept drawings on scraps of napkins to a 32 eV at 1.5 keV energy resolution 7-pixel PoST calorimeter.

  13. Two-dimensional spectrally resolved position-sensitive proportional counter for plasma imaging

    SciTech Connect

    Thorn, D.; Beiersdorfer, P.

    2004-10-01

    We describe a 160x100 mm two-dimensional position-sensitive proportional counter for use in high-temperature plasma spectroscopy. The detector employs a novel design based on a printed circuit board for the cathode plane and a single-wire switchback design for the anode plane. The spacial resolution for one dimension is 200 {mu}m and for the other dimension is 2-5 mm. The integral nonlinearity is 0.08% for the first and 1% for the second dimension. We demonstrate the utility of the new detector with a spacially resolved measurement of the Lyman-{alpha} transitions in hydrogenic Ar{sup 17+}.

  14. Study of Capillary-Based Gaseous Detectors

    NASA Astrophysics Data System (ADS)

    Iacobaeus, C.; Francke, T.; Danielsson, M.; Ostling, J.; Peskov, V.

    2004-06-01

    We have studied gain vs. voltage characteristics and position resolutions of multistep capillary plates (two or three capillary plates operating in a cascade), as well as capillary plates operating in a mode when the main amplification occurs between plates or between the capillary plate and the readout plate (parallel plate amplification mode). Results of these studies demonstrated that in the parallel-plate amplification mode one can reach both high gains (>100000) and good position resolutions (~100 micro meter) even with a single step arrangement. It offers a compact amplification structure, which can be used in many applications. For example, in preliminary tests we succeeded to combine it with a photocathode and use it as a position sensitive gaseous photomultiplier. CsI coated capillary plates could also be used as a high position resolution and high rate X-ray converter.

  15. Proportional counter for X-ray analysis of lunar and planetary surfaces. [a position sensitive scintillating imaging proportional counter

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A position sensitive proportional scintillation detector was developed and evaluated for use in applications involving X-ray imaging as well as spectroscopy. Topics covered include limitations of the proportional scintillation counter for use in space; purification of the xenon gas in the detector, and the operation of the detector system. Results show that the light signal in a proportional scintillation detector remains well localized. With modest electric fields in xenon, the primary electrons from a photoelectric absorption of an X-ray can be brought a distance of a few millimeters to a higher field region without spreading more than a millimeter or so. Therefore, it is possible to make a proportional scintillation detector with good position sensitivity that could be used to calibrate out the difference in light collection over its sensitive volume.

  16. Development of three-dimensional position-sensitive room temperature semiconductor gamma-ray spectrometers

    SciTech Connect

    He, Z.; Li, W.; Knoll, G.F.; Wehe, D.K.

    2000-07-01

    Semiconductor detectors can provide better spectroscopic performance than scintillation or gas-filled detectors because of the small ionization energy required to generate each electron-hole pair. Indeed, cryogenically cooled high-purity germanium detectors have played the dominant role whenever the best gamma-ray spectroscopy is required. A decades-long search for other semiconductor detectors that could provide higher stopping power and could operate at room temperature has been ongoing. Wide-band-gap semiconductors, such as CdTe, CdZnTe, and HgI{sub 2}, have captured the most attention. However, the use of these semiconductors in detectors has been hindered primarily by problems of charge trapping and material nonuniformity. Introduced in 1994, single-polarity charge sensing on semiconductor detectors has shown great promise in avoiding the hole-trapping problem, and the newly demonstrated three-dimensional position-sensing technique can significantly mitigate the degradation of energy resolution due to the nonuniformity of detector material. In addition, three-dimensional position sensitivity will provide unique imaging capabilities of these gamma-ray spectrometers. These devices are of interest for nuclear nonproliferation, medical imaging, gamma-ray astronomy, and high-energy physics applications. This paper reports the latest results using second-generation three-dimensional position-sensitive semiconductor spectrometers. The improvements over the first generation devices include: (1) Larger volume; (2) Improved anode design; (3) More reliable connections; (4) Enhanced electronic capability; and (5) Measurement of electron drift times. The new detectors and readout electronics (from IDE AS) are being assembled and tested.

  17. Monte Carlo study of microdosimetric diamond detectors.

    PubMed

    Solevi, Paola; Magrin, Giulio; Moro, Davide; Mayer, Ramona

    2015-09-21

    Ion-beam therapy provides a high dose conformity and increased radiobiological effectiveness with respect to conventional radiation-therapy. Strict constraints on the maximum uncertainty on the biological weighted dose and consequently on the biological weighting factor require the determination of the radiation quality, defined as the types and energy spectra of the radiation at a specific point. However the experimental determination of radiation quality, in particular for an internal target, is not simple and the features of ion interactions and treatment delivery require dedicated and optimized detectors. Recently chemical vapor deposition (CVD) diamond detectors have been suggested as ion-beam therapy microdosimeters. Diamond detectors can be manufactured with small cross sections and thin shapes, ideal to cope with the high fluence rate. However the sensitive volume of solid state detectors significantly deviates from conventional microdosimeters, with a diameter that can be up to 1000 times the height. This difference requires a redefinition of the concept of sensitive thickness and a deep study of the secondary to primary radiation, of the wall effects and of the impact of the orientation of the detector with respect to the radiation field. The present work intends to study through Monte Carlo simulations the impact of the detector geometry on the determination of radiation quality quantities, in particular on the relative contribution of primary and secondary radiation. The dependence of microdosimetric quantities such as the unrestricted linear energy L and the lineal energy y are investigated for different detector cross sections, by varying the particle type (carbon ions and protons) and its energy.

  18. Monte Carlo study of microdosimetric diamond detectors

    NASA Astrophysics Data System (ADS)

    Solevi, Paola; Magrin, Giulio; Moro, Davide; Mayer, Ramona

    2015-09-01

    Ion-beam therapy provides a high dose conformity and increased radiobiological effectiveness with respect to conventional radiation-therapy. Strict constraints on the maximum uncertainty on the biological weighted dose and consequently on the biological weighting factor require the determination of the radiation quality, defined as the types and energy spectra of the radiation at a specific point. However the experimental determination of radiation quality, in particular for an internal target, is not simple and the features of ion interactions and treatment delivery require dedicated and optimized detectors. Recently chemical vapor deposition (CVD) diamond detectors have been suggested as ion-beam therapy microdosimeters. Diamond detectors can be manufactured with small cross sections and thin shapes, ideal to cope with the high fluence rate. However the sensitive volume of solid state detectors significantly deviates from conventional microdosimeters, with a diameter that can be up to 1000 times the height. This difference requires a redefinition of the concept of sensitive thickness and a deep study of the secondary to primary radiation, of the wall effects and of the impact of the orientation of the detector with respect to the radiation field. The present work intends to study through Monte Carlo simulations the impact of the detector geometry on the determination of radiation quality quantities, in particular on the relative contribution of primary and secondary radiation. The dependence of microdosimetric quantities such as the unrestricted linear energy L and the lineal energy y are investigated for different detector cross sections, by varying the particle type (carbon ions and protons) and its energy.

  19. Implementation of Complex Signal Processing Algorithms for Position-Sensitive Microcalorimeters

    NASA Technical Reports Server (NTRS)

    Smith, Stephen J.

    2008-01-01

    We have recently reported on a theoretical digital signal-processing algorithm for improved energy and position resolution in position-sensitive, transition-edge sensor (POST) X-ray detectors [Smith et al., Nucl, lnstr and Meth. A 556 (2006) 2371. PoST's consists of one or more transition-edge sensors (TES's) on a large continuous or pixellated X-ray absorber and are under development as an alternative to arrays of single pixel TES's. PoST's provide a means to increase the field-of-view for the fewest number of read-out channels. In this contribution we extend the theoretical correlated energy position optimal filter (CEPOF) algorithm (originally developed for 2-TES continuous absorber PoST's) to investigate the practical implementation on multi-pixel single TES PoST's or Hydras. We use numerically simulated data for a nine absorber device, which includes realistic detector noise, to demonstrate an iterative scheme that enables convergence on the correct photon absorption position and energy without any a priori assumptions. The position sensitivity of the CEPOF implemented on simulated data agrees very well with the theoretically predicted resolution. We discuss practical issues such as the impact of random arrival phase of the measured data on the performance of the CEPOF. The CEPOF algorithm demonstrates that full-width-at- half-maximum energy resolution of < 8 eV coupled with position-sensitivity down to a few 100 eV should be achievable for a fully optimized device.

  20. Position sensitivity of graphene field effect transistors to X-rays

    SciTech Connect

    Cazalas, Edward Moore, Michael E.; Jovanovic, Igor; Sarker, Biddut K.; Childres, Isaac; Chen, Yong P.

    2015-06-01

    Device architectures that incorporate graphene to realize detection of electromagnetic radiation typically utilize the direct absorbance of radiation by graphene. This limits their effective area to the size of the graphene and their applicability to lower-energy, less penetrating forms of radiation. In contrast, graphene-based transistor architectures that utilize the field effect as the detection mechanism can be sensitive to interactions of radiation not only with graphene but also with the surrounding substrate. Here, we report the study of the position sensitivity and response of a graphene-based field effect transistor (GFET) to penetrating, well-collimated radiation (micro-beam X-rays), producing ionization in the substrate primarily away from graphene. It is found that responsivity and response speed are strongly dependent on the X-ray beam distance from graphene and the gate voltage applied to the GFET. To develop an understanding of the spatially dependent response, a model is developed that incorporates the volumetric charge generation, transport, and recombination. The model is in good agreement with the observed spatial response characteristics of the GFET and predicts a greater response potential of the GFET to radiation interacting near its surface. The study undertaken provides the necessary insight into the volumetric nature of the GFET response, essential for development of GFET-based detectors for more penetrating forms of ionizing radiation.

  1. Position-sensitive detection of slow neutrons: Survey of fundamental principles

    SciTech Connect

    Crawford, R.K.

    1992-01-01

    This paper sets forth the fundamental principles governing the development of position-sensitive detection systems for slow neutrons. Since neutrons are only weakly interacting with most materials, it is not generally practical to detect slow neutrons directly. Therefore all practical slow neutron detection mechanisms depend on the use of nuclear reactions to convert'' the neutron to one or more charged particles, followed by the subsequent detection of the charged particles. The different conversion reactions which can be used are discussed, along with the relative merits of each. This is followed with a discussion of the various methods of charged particle detection, how these lend themselves to position-sensitive encoding, and the means of position encoding which can be applied to each case. Detector performance characteristics which may be of importance to the end user are discussed and related to these various detection and position-encoding mechanisms.

  2. Position-sensitive detection of slow neutrons: Survey of fundamental principles

    SciTech Connect

    Crawford, R.K.

    1992-07-01

    This paper sets forth the fundamental principles governing the development of position-sensitive detection systems for slow neutrons. Since neutrons are only weakly interacting with most materials, it is not generally practical to detect slow neutrons directly. Therefore all practical slow neutron detection mechanisms depend on the use of nuclear reactions to ``convert`` the neutron to one or more charged particles, followed by the subsequent detection of the charged particles. The different conversion reactions which can be used are discussed, along with the relative merits of each. This is followed with a discussion of the various methods of charged particle detection, how these lend themselves to position-sensitive encoding, and the means of position encoding which can be applied to each case. Detector performance characteristics which may be of importance to the end user are discussed and related to these various detection and position-encoding mechanisms.

  3. The particle background of the Rosat PSPC. [Position Sensitive Proportional Counter

    NASA Technical Reports Server (NTRS)

    Snowden, S. L.; Plucinsky, P. P.; Briel, U.; Hasinger, G.; Pfeffermann, E.

    1992-01-01

    In order to permit quantitative studies of the diffuse cosmic X-ray background and of extended X-ray sources, the particle induced background of the Roentgen Satellite, Rosat, Position Sensitive Proportional Counter (PSPC) is parameterized. Data collected during 210,000 s of PSPC operation have been analyzed and the temporal, spectral, and spatial distributions investigated. About 77 percent of the residual events originate within the detector while the remainder enter through the counter window. During typical conditions, the count rate of the residual events is well correlated with the Master Veto (MV) count rate. The spectrum of these events is well described by a flat component plus a soft power law and an Al K-alpha line at 1.5 keV. Also during typical conditions, the ratio between the power law and flat components remains constant to +/- 4 while the relative Al K-alpha contribution increases with increasing MV count rate. The distribution of the counts over the field of view is uniform except for a slight radial dependence and shadowing caused by blockage of the externally produced component by the window support structure.

  4. Study of air pollutant detectors

    NASA Technical Reports Server (NTRS)

    Gutshall, P. L.; Bowles, C. Q.

    1974-01-01

    The application of field ionization mass spectrometry (FIMS) to the detection of air pollutants was investigated. Current methods are reviewed for measuring contaminants of fixed gases, sulfur compounds, nitrogen oxides, hydrocarbons, and particulates. Two enriching devices: the dimethyl silicone rubber membrane separator, and the selective adsorber of polyethylene foam were studied along with FIMS. It is concluded that the membrane enricher system is not a suitable method for removing air pollutants. However, the FIMS shows promise as a useable system for air pollution detection.

  5. Oil spill detector device studied

    SciTech Connect

    Not Available

    1980-03-01

    Nereides S.A., France, has commissioned the Institute Francais du Petrole (IFP) to study a membrane called IFP FUSE, which is capable of dissolution by hydrocarbons enabling the user to reliably and inexpensively detect oil spills at sea, in lakes, in rivers, and in rainwater. The membrane is stretched between two springs, which hold open a magnetic circuit breaker, and the entire unit is partially submerged in water. On contact with hydrocarbons, the membrane dissolves and frees the spring tension, thus transmitting a 48 h alarm through cable or radiowave. The membrane is made of thin film (0.1 mm), stable to water and air and highly sensitive to most hydrocarbons, crude oil, and refined products. Dissolution time in thin layers, depending on the hydrocarbon, is 5 sec to 13 min for crude oil, gas oil and domestic fuel, kerosene, isooctane, benzene, toluene, xylene, chlorinated solvents, and acetone. The membrane, guaranteed for three months, can be installed on oil terminals, airplane-launched buoys, and small floats.

  6. Position sensitive radioactivity detection for gas and liquid chromatography

    DOEpatents

    Cochran, Joseph L.; McCarthy, John F.; Palumbo, Anthony V.; Phelps, Tommy J.

    2001-01-01

    A method and apparatus are provided for the position sensitive detection of radioactivity in a fluid stream, particularly in the effluent fluid stream from a gas or liquid chromatographic instrument. The invention represents a significant advance in efficiency and cost reduction compared with current efforts.

  7. Spatial distortion correction and crystal identification for MRI-compatible position-sensitive avalanche photodiode-based PET scanners.

    PubMed

    Chaudhari, Abhijit J; Joshi, Anand A; Wu, Yibao; Leahy, Richard M; Cherry, Simon R; Badawi, Ramsey D

    2009-06-01

    Position-sensitive avalanche photodiodes (PSAPDs) are gaining widespread acceptance in modern PET scanner designs, and owing to their relative insensitivity to magnetic fields, especially in those that are MRI-compatible. Flood histograms in PET scanners are used to determine the crystal of annihilation photon interaction and hence, for detector characterization and routine quality control. For PET detectors that use PSAPDs, flood histograms show a characteristic pincushion distortion when Anger logic is used for event positioning. A small rotation in the flood histogram is also observed when the detectors are placed in a magnetic field. We first present a general purpose automatic method for spatial distortion correction for flood histograms of PSAPD-based PET detectors when placed both inside and outside a MRI scanner. Analytical formulae derived for this scheme are based on a hybrid approach that combines desirable properties from two existing event positioning schemes. The rotation of the flood histogram due to the magnetic field is determined iteratively and is accounted for in the scheme. We then provide implementation details of a method for crystal identification we have previously proposed and evaluate it for cases when the PET detectors are both outside and in a magnetic field. In this scheme, Fourier analysis is used to generate a lower-order spatial approximation of the distortion-corrected PSAPD flood histogram, which we call the 'template'. The template is then registered to the flood histogram using a diffeomorphic iterative intensity-based warping scheme. The calculated deformation field is then applied to the segmentation of the template to obtain a segmentation of the flood histogram. A manual correction tool is also developed for exceptional cases. We present a quantitative assessment of the proposed distortion correction scheme and crystal identification method against conventional methods. Our results indicate that our proposed methods lead to

  8. Detectors

    DOEpatents

    Orr, Christopher Henry; Luff, Craig Janson; Dockray, Thomas; Macarthur, Duncan Whittemore; Bounds, John Alan; Allander, Krag

    2002-01-01

    The apparatus and method provide techniques through which both alpha and beta emission determinations can be made simultaneously using a simple detector structure. The technique uses a beta detector covered in an electrically conducting material, the electrically conducting material discharging ions generated by alpha emissions, and as a consequence providing a measure of those alpha emissions. The technique also offers improved mountings for alpha detectors and other forms of detectors against vibration and the consequential effects vibration has on measurement accuracy.

  9. Fast two-dimensional position-sensitive detection of neutrons in a time-of-flight reflectometer

    NASA Astrophysics Data System (ADS)

    van de Kruijs, R. W. E.; de Blois, J.

    2002-04-01

    A two-dimensional position-sensitive neutron detector with a maximum count rate of 500 kHz is described. The high counting rate is obtained by making use of dedicated electronics for data handling. The electronics convert the wire charges of a position-sensitive photomultiplier into a position using internal look-up tables. Timing modules are presented for neutron time-of-flight (TOF) determination and for dynamic measurements with an independent time-base. The position and TOF information are stored by a fast Data Handling Module. The detector is calibrated with a grid of 256×256 channels, using channel widths of 0.25 mm.The maximum error in position determination is 0.25 mm.This error is reduced to less than 0.05 mm when the electronics are used one dimensionally instead of two dimensionally. The total detector resolution was determined to be 0.6 mm.

  10. Simulation study of pixel detector charge digitization

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  11. [Study on photographing experiment of infrared detector].

    PubMed

    Wang, De-Jiang; Zhang, Tao

    2011-01-01

    Infrared detectors are widely used in multi spectral remote sensing systems, and in order to verify photographing principles of infrared time delay integration (TDI) detector, and make preparations for future research, a verification system for infrared TDI camera is proposed in the present paper. Experimental methods are explained thoroughly and two major factors which affect image quality are analyzed. First, the causes of image motion and their effects on the quality of image are studied, and a novel architecture using high precision DC-speed machine is presented, then the relationship between velocity of precision turntable and detectors line transfer frequency is determined by Kalman algorithm. Second, four focusing means are analyzed and compared, and video signal amplitude method is selected according to practical application. Finally, a genuine demo system is established in national supervision and test center for optics mechanics quality. 5.3, 6.4 and 9.2 mm drones are chosen for testing. Experimental results indicate that the obtained drone is vivid, and camera's resolution achieves 11.3 lines per mm, which satisfies preliminary aims.

  12. Dynamic phenomena studied with a CCD detector

    SciTech Connect

    Brizard, C.M.; Rodricks, B.G.; Alp, E.E. ); MacHarrie, R. )

    1991-08-01

    A new programmable charge coupled device (CCD) detector based on the CAMAC (Computer Automated Measurement and Control) modular system and coupled to a MircoVax 3 computer has been developed for time-resolved synchrotron experiments. The programmability of the electronics allows one to use many kinds of CCD chip. Moreover, different detector modes can be chosen according to the time scale of the experiment. Various time-resolved x-ray scattering experiments have already been performed at NSLS and CHESS with this imaging system. For example, a real-time study of the early stages of crystallization of the amorphous metallic alloy Fe{sub 80}B{sub 20} was carried out at the X6 beamline at NSLS. Here a spin melt ribbon of the amorphous metal was resistively heated in stages in 600{degrees}C and the crystallization observed on the CCD. The detector angular acceptance of 3{degrees} allowed for the observation of the evolution of the {alpha}-Fe, and Fe{sub 3}B and the Fe{sub 2}B phases simultaneously on a minute time scale.

  13. A two-dimensional position sensitive gas chamber with scanned charge transfer readout

    NASA Astrophysics Data System (ADS)

    Gómez, F.; Iglesias, A.; Lobato, R.; Mosquera, J.; Pardo, J.; Pena, J.; Pazos, A.; Pombar, M.; Rodríguez, A.

    2003-10-01

    We have constructed and tested a two-dimensional position sensitive parallel-plate gas ionization chamber with scanned charge transfer readout. The scan readout method described here is based on the development of a new position-dependent charge transfer technique. It has been implemented by using gate strips perpendicularly oriented to the collector strips. This solution reduces considerably the number of electronic readout channels needed to cover large detector areas. The use of a 25 μm thick kapton etched circuit allows high charge transfer efficiency with a low gating voltage, consequently needing a very simple commutating circuit. The present prototype covers 8×8 cm2 with a pixel size of 1.27×1.27 mm2. Depending on the intended use and beam characteristics a smaller effective pixel is feasible and larger active areas are possible. This detector can be used for X-ray or other continuous beam intensity profile monitoring.

  14. Comparative Study of Edge Detectors in case of Echocardiographic Images

    NASA Astrophysics Data System (ADS)

    Saini, Kalpana; Dewal, M. L.; Rohit, Manoj Kumar

    2010-11-01

    In this paper we compare different edge detectors based on peak signal to noise ratio on Echocardiographic images. Edge detection is a critical element in image processing, since edges contain a major function of image information. The function of edge detection is to identify the boundaries of homogeneous regions in an image based on properties such as intensity and texture.We have taken Perwitt edge detector, Robarts edge detector, LoG edge detector, Canny edge detector, and Sobel edge detector for this comparison and study.

  15. Studies of double-sided silicon microstrip detectors

    NASA Astrophysics Data System (ADS)

    Seidel, S. C.; Bruner, N. L.; Frautschi, M. A.; Hoeferkamp, M. R.; Patton, A.

    1996-02-01

    The electrical characteristics of detectors manufactured by SINTEF/SI with a variety of geometrical and processing options have been investigated. The detectors' leakage current, depletion voltage, bias resistance, interstrip, coupling capacitance, and coupling capacitor breakdown voltage were studied.

  16. Studies of double-sided silicon microstrip detectors

    SciTech Connect

    Seidel, S.C.; Bruner, N.L.; Frautsch, M.A.; Hoeferkamp, M.R.; Patton, A.

    1996-03-01

    The electrical characteristics of detectors manufactured by SINTEF/SI with a variety of geometrical and processing options have been investigated. The detectors` leakage current, depletion voltage, bias resistance, interstrip resistance, coupling capacitance, and coupling capacitor breakdown voltage were studied.

  17. Superconducting Detectors for Study of Infant Universe

    NASA Image and Video Library

    2014-03-17

    The BICEP2 telescope at the South Pole used a specialized array of superconducting detectors to capture polarized light from billions of years ago. The detector array is shown here, under a microscope.

  18. Determination of (235)U, (239)Pu, (240)Pu, and (241)Am in a nuclear bomb particle using a position-sensitive α-γ coincidence technique.

    PubMed

    Peräjärvi, Kari A; Ihantola, Sakari; Pöllänen, Roy C; Toivonen, Harri I; Turunen, Jani A

    2011-02-15

    A nuclear bomb particle containing 1.6 ng of Pu was investigated nondestructively with a position-sensitive α detector and a broad-energy HPGe γ-ray detector. An event-mode data acquisition system was used to record the data. α-γ coincidence counting was shown to be well suited to nondestructive isotope ratio determination. Because of the very small background, the 51.6 keV γ rays of (239)Pu and the 45.2 keV γ rays of (240)Pu were identified, which enabled isotopic ratio calculations. In the present work, the (239)Pu/((239)Pu+(240)Pu) atom ratio was determined to be 0.950 ± 0.010. The uncertainties were much smaller than in the previous more conventional nondestructive studies on this particle. Obtained results are also in good agreement with the data from the destructive mass spectrometric studies obtained previously by other investigators.

  19. Studies on sensitive Raman gas detectors

    NASA Astrophysics Data System (ADS)

    Zuo, Duluo; Xu, Yongyue; Wang, Xinbing; Xiong, Youhui

    2013-05-01

    Recent studies on signal enhancement of spontaneous Raman scattering for developing of sensitive Raman gas detectors are reported. Raman scattering is a gas detecting method with high feasibility, but usually its signal is very low. To improve the level and the quality of the Raman signal, the effects of pumping laser source, sample cell, and optical arrangement are studied in detail. It is found that not only the wall of sample cell will give a wide Raman or fluorescence background which will decrease the sensitivity, but the dichroic beam splitter will also contribute considerable background if it is not aligned properly. The sample cell of hollow fiber is characterized by its high responsibility as well as its high background and low signal contrast. When the hollow fiber is replaced by a free-space sample cell consisted of metal-coated parabolic reflector, the wide background is largely suppressed. If there is no common optical elements between the pumping and collecting optical systems, the wide background will be cut down obviously, which is proved by the intracavity-enhanced Raman scattering in a He-Ne laser. These experimental results will be helpful for the research and developing of highly sensitive Raman gas detectors.

  20. Alpha particle response study of polycrstalline diamond radiation detector

    SciTech Connect

    Kumar, Amit; Topkar, Anita

    2016-05-23

    Chemical vapor deposition has opened the possibility to grow high purity synthetic diamond at relatively low cost. This has opened up uses of diamond based detectors for wide range of applications. These detectors are most suitable for harsh environments where standard semiconductor detectors cannot work. In this paper, we present the fabrication details and performance study of polycrystalline diamond based radiation detector. Effect of different operating parameters such as bias voltage and shaping time for charge collection on the performance of detector has been studied.

  1. Detector design studies for Turkish Accelerator Center

    NASA Astrophysics Data System (ADS)

    Aksu, Burçin; Piliçer, Ercan

    2017-02-01

    The proposed Particle Factory detector at Turkish Accelerator Center (TAC-PF) aims to search for charm physics, CP violation and mixing of D0 mesons as well as new physics effects by investigating head-on collisions of 1 GeV electron from Energy Recovery Linac (ERL) with 3.56 GeV positrons from synchrotron storage ring. In this work, we constructed the TAC-PF detector design by using a recently developed framework namely Detector Description for High Energy Physics (DD4hep). The baseline TAC-PF detector design and its qualifications were summarized, followed by a general description.

  2. Design and Technical Study of Neutrino Detector Spacecraft

    NASA Technical Reports Server (NTRS)

    Solomey, Niclolas

    2017-01-01

    A neutrino detector is proposed to be developed for use on a space probe in close orbit of the Sun. The detector will also be protected from radiation by a tungsten shield Sun shade, active veto array and passive cosmic shielding. With the intensity of solar neutrinos substantially greater in a close solar orbit than on the Earth only a small 250 kg detector is needed. It is expected that this detector and space probe studying the core of the Sun, its nuclear furnace and particle physics basic properties will bring new knowledge beyond what is currently possible for Earth bound solar neutrino detectors.

  3. Position sensitivity in 3"×3" Spectroscopic LaBr3:Ce Crystals

    NASA Astrophysics Data System (ADS)

    Blasi, N.; Giaz, A.; Boiano, C.; Brambilla, S.; Camera, F.; Million, B.; Riboldi, S.

    2015-06-01

    The position sensitivity of a thick, cylindrical and continuous 3" × 3" (7.62 cm × 7.62 cm) LaBr3:Ce crystal with diffusive surfaces was investigated. Nuclear physics basic research uses thick LaBr3:Ce crystals (> 3cm) to measure medium or high energy gamma rays (0.5 MeV < Eγ< 20 MeV). In the first measurement the PMT photocathode entrance window was covered by black absorber except for a small window 1 cm × 1cm wide. A complete scan of the detector over a 0.5 cm step grid was performed. The data show that even in a 3" thick LaBr3:Ce crystal with diffusive surfaces the position of the full energy peak centroid depends on the source position. The position of the full energy peak centroids are sufficient to identify the collimated gamma source position. The crystal was then coupled to four Position Sensitive Photomultipliers (PSPMT). We acquired the signals from the 256 segments of the four PSPMTs grouping them into 16 elements. An event by event analysis shows a positon resolution of the order of 2 cm.

  4. Development of position-sensitive time-of-flight spectrometer for fission fragment research

    SciTech Connect

    Arnold, C. W.; Tovesson, F.; Meierbachtol, K.; Bredeweg, T.; Jandel, M.; Jorgenson, H. J.; Laptev, A.; Rusev, G.; Shields, D. W.; White, M.; Blakeley, R. E.; Mader, D. M.; Hecht, A. A.

    2014-07-09

    A position-sensitive, high-resolution time-of-flight detector for fission fragments has been developed. The SPectrometer for Ion DEtermination in fission Research (SPIDER) is a 2E–2v spectrometer designed to measure the mass of light fission fragments to a single mass unit. The time pick-off detector pairs to be used in SPIDER have been tested with α-particles from 229Th and its decay chain and α-particles and spontaneous fission fragments from 252Cf. Each detector module is comprised of thin electron conversion foil, electrostatic mirror, microchannel plates, and delay-line anodes. Particle trajectories on the order of 700 mm are determined accurately to within 0.7 mm. Flight times were measured with 250 ps resolution FWHM. Computed particle velocities are accurate to within 0.06 mm/ns corresponding to a precision of 0.5%. As a result, an ionization chamber capable of 400 keV energy resolution coupled with the velocity measurements described here will pave the way for modestly efficient measurements of light fission fragments with unit mass resolution.

  5. Development of position-sensitive time-of-flight spectrometer for fission fragment research

    DOE PAGES

    Arnold, C. W.; Tovesson, F.; Meierbachtol, K.; ...

    2014-07-09

    A position-sensitive, high-resolution time-of-flight detector for fission fragments has been developed. The SPectrometer for Ion DEtermination in fission Research (SPIDER) is a 2E–2v spectrometer designed to measure the mass of light fission fragments to a single mass unit. The time pick-off detector pairs to be used in SPIDER have been tested with α-particles from 229Th and its decay chain and α-particles and spontaneous fission fragments from 252Cf. Each detector module is comprised of thin electron conversion foil, electrostatic mirror, microchannel plates, and delay-line anodes. Particle trajectories on the order of 700 mm are determined accurately to within 0.7 mm. Flightmore » times were measured with 250 ps resolution FWHM. Computed particle velocities are accurate to within 0.06 mm/ns corresponding to a precision of 0.5%. As a result, an ionization chamber capable of 400 keV energy resolution coupled with the velocity measurements described here will pave the way for modestly efficient measurements of light fission fragments with unit mass resolution.« less

  6. Spatial distortion correction and crystal identification for MRI-compatible position-sensitive avalanche photodiode-based PET scanners

    PubMed Central

    Chaudhari, Abhijit J.; Joshi, Anand A.; Wu, Yibao; Leahy, Richard M.; Cherry, Simon R.; Badawi, Ramsey D.

    2009-01-01

    Position-sensitive avalanche photodiodes (PSAPDs) are gaining widespread acceptance in modern PET scanner designs, and owing to their relative insensitivity to magnetic fields, especially in those that are MRI-compatible. Flood histograms in PET scanners are used to determine the crystal of annihilation photon interaction and hence, for detector characterization and routine quality control. For PET detectors that use PSAPDs, flood histograms show a characteristic pincushion distortion when Anger logic is used for event positioning. A small rotation in the flood histogram is also observed when the detectors are placed in a magnetic field. We first present a general purpose automatic method for spatial distortion correction for flood histograms of PSAPD-based PET detectors when placed both inside and outside a MRI scanner. Analytical formulae derived for this scheme are based on a hybrid approach that combines desirable properties from two existing event positioning schemes. The rotation of the flood histogram due to the magnetic field is determined iteratively and is accounted for in the scheme. We then provide implementation details of a method for crystal identification we have previously proposed and evaluate it for cases when the PET detectors are both outside and in a magnetic field. In this scheme, Fourier analysis is used to generate a lower-order spatial approximation of the distortion-corrected PSAPD flood histogram, which we call the ‘template’. The template is then registered to the flood histogram using a diffeomorphic iterative intensity-based warping scheme. The calculated deformation field is then applied to the segmentation of the template to obtain a segmentation of the flood histogram. A manual correction tool is also developed for exceptional cases. We present a quantitative assessment of the proposed distortion correction scheme and crystal identification method against conventional methods. Our results indicate that our proposed methods lead

  7. Radiation damage studies for the D0 silicon detector

    SciTech Connect

    Lehner, F.; /Zurich U.

    2004-01-01

    We report on irradiation studies performed on spare production silicon detector modules for the current D0 silicon detector. The lifetime expectations due to radiation damage effects of the existing silicon detector are reviewed. A new upgrade project was started with the goal of a complete replacement of the existing silicon detector. In that context, several investigations on the radiation hardness of new prototype silicon microstrip detectors were carried out. The irradiation on different detector types was performed with 10 MeV protons up to fluences of 10{sup 14} p/cm{sup 2} at the J.R. Mcdonald Laboratory at Kansas State University. The flux calibration was carefully checked using different normalization techniques. As a result, we observe roughly 40-50% less radiation damage in silicon for 10 MeV p exposure than it is expected by the predicted NIEL scaling.

  8. A New Positioning Algorithm for Position-Sensitive Avalanche Photodiodes

    PubMed Central

    Zhang, Jin; Olcott, Peter D.; Levin, Craig S.

    2013-01-01

    We are using a novel position sensitive avalanche photodiode (PSAPD) for the construction of a high resolution positron emission tomography (PET) camera. Up to now most researchers working with PSAPDs have been using an Anger-like positioning algorithm involving the four corner readout signals of the PSAPD. This algorithm yields a significant non-linear spatial “pin-cushion” distortion in raw crystal positioning histograms. In this paper, we report an improved positioning algorithm, which combines two diagonal corner signals of the PSAPD followed by a 45° rotation to determine the X or Y position of the interaction. We present flood positioning histogram data generated with the old and new positioning algorithms using a 3 × 4 array of 2 × 2 × 3 mm3 and a 3 × 8 array of 1 × 1 × 3 mm3 of LSO crystals coupled to 8 × 8 mm2 PSAPDs. This new algorithm significantly reduces the pin-cushion distortion in raw flood histogram image. PMID:24307743

  9. A New Positioning Algorithm for Position-Sensitive Avalanche Photodiodes.

    PubMed

    Zhang, Jin; Olcott, Peter D; Levin, Craig S

    2007-06-01

    We are using a novel position sensitive avalanche photodiode (PSAPD) for the construction of a high resolution positron emission tomography (PET) camera. Up to now most researchers working with PSAPDs have been using an Anger-like positioning algorithm involving the four corner readout signals of the PSAPD. This algorithm yields a significant non-linear spatial "pin-cushion" distortion in raw crystal positioning histograms. In this paper, we report an improved positioning algorithm, which combines two diagonal corner signals of the PSAPD followed by a 45° rotation to determine the X or Y position of the interaction. We present flood positioning histogram data generated with the old and new positioning algorithms using a 3 × 4 array of 2 × 2 × 3 mm(3) and a 3 × 8 array of 1 × 1 × 3 mm(3) of LSO crystals coupled to 8 × 8 mm(2) PSAPDs. This new algorithm significantly reduces the pin-cushion distortion in raw flood histogram image.

  10. Canadian Penning Trap Mass Measurements using a Position Sensitive MCP

    NASA Astrophysics Data System (ADS)

    Kuta, Trenton; Aprahamian, Ani; Marley, Scott; Nystrom, Andrew; Clark, Jason; Perez Galvan, Adrian; Hirsh, Tsviki; Savard, Guy; Orford, Rodney; Morgan, Graeme

    2015-10-01

    The primary focus of the Canadian Penning Trap (CPT) located at Argonne National Lab is to determine the masses of various isotopes produced in the spontaneous fission of Californium. Currently, the CPT is operating in conjunction with CARIBU at the ATLAS facility in an attempt to measure neutron-rich nuclei produced by a 1.5 Curie source of Californium 252. The masses of nuclei produced in fission is accomplished by measuring the cyclotron frequency of the isotopes circling within the trap. This frequency is determined by a position sensitive MCP, which records the relative position of the isotope in the trap at different times. Using these position changes over time in connection with a center spot, angles between these positions are calculated and used to determine the frequency. Most of the work currently being conducted on the CPT is focused on the precision of these frequency measurements. The use of traps has revolutionized the measurements of nuclear masses to very high precision. The optimization methods employed here include focusing the beam in order to reduce the spread on the position of the isotope as well as the tuning of the MR-ToF, a mass separator that is intended on removing contaminants in the beam. This work was supported by the nuclear Grant PHY-1419765 for the University of Notre Dame.

  11. A Study of 3He detectors for Active Interrogation

    SciTech Connect

    E.H. Seabury; D.L. Chichester

    2009-10-01

    3He proportional counters have long been used as neutron detectors for both passive and active detection of Special Nuclear Material (SNM). The optimal configuration of these detectors as far as gas pressure, amount of moderating material, and size are concerned is highly dependent on what neutron signatures are being used to detect and identify SNM. We present here a parametric study of the neutron capture response of 3He detectors, based on Monte Carlo simulations using the MCNPX radiation transport code. The neutron capture response of the detectors has been modeled as a function of time after an incident neutron pulse.

  12. Cosmic ray studies with the MINOS detectors

    NASA Astrophysics Data System (ADS)

    Habig, Alec; Minos Collaboration

    2008-11-01

    The MINOS experiment uses two layered scintillator and steel detectors along with a muon neutrino beam to search for νμ disappearance, and thus neutrino oscillations. The Far Detector ('FD') is situated in a former iron mine in the Soudan Underground Mine State Park in Northeastern MN, 700 m (2070 mwe) below the surface. This 5.4 kt steel/scintillator calorimeter measures the neutrino flux after they have traveled the 735 km baseline. It also detects atmospheric neutrinos at a rate of several per week, and is the first magnetized atmospheric neutrino detector, able to discriminate between νμ and νμ on an event-by-event basis. The similar 1 kt Near Detector ('ND') is 100 m (220 mwe) underground at Fermilab. This poster discusses the science being done with the high energy cosmic ray muons which penetrate the rock overburden and are seen by the detectors. The typical surface energy of those seen at the FD are ~1 TeV (coming from ~8 TeV primary cosmic rays) and ~110 GeV at the ND (~900 GeV primaries).

  13. A Simple Capacitive Charge-Division Readout for Position-Sensitive Solid-State Photomultiplier Arrays

    PubMed Central

    Du, Junwei; Schmall, Jeffrey P.; Yang, Yongfeng; Di, Kun; Dokhale, Purushottam A.; Shah, Kanai S.; Cherry, Simon R.

    2014-01-01

    A capacitive charge-division readout method for reading out a 2 × 2 array of 5 mm × 5 mm position-sensitive solid-state photomultipliers (PS-SSPM) was designed and evaluated. Using this analog multiplexing method, the 20 signals (16 position, 4 timing) from the PS-SSPM array are reduced to 5 signals (4 position, 1 timing), allowing the PS-SSPM array to be treated as an individual large-area PS-SSPM module. A global positioning approach can now be used, instead of individual positioning for each PS-SSPM in the array, ensuring that the entire light signal is utilized. The signal-to-noise ratio (SNR) and flood histogram quality at different bias voltages (27.5 V to 32.0 V at 0.5 V intervals) and a fixed temperature of 0 °C were evaluated by coupling a 6 × 6 array of 1.3 mm × 1.3 mm × 20 mm polished LSO crystals to the center of the PS-SSPM array. The timing resolution was measured at a fixed bias voltage of 31.0 V and a fixed temperature of 0 °C. All the measurements were evaluated and compared using capacitors with different values and tolerances. Capacitor values ranged from 0.051 nf to 10 nf, and the capacitance tolerance ranged from 1% to 20%. The results show that better performance was achieved using capacitors with smaller values and better capacitance tolerance. Using 0.2 nf capacitors, the SNR, energy resolution and timing resolution were 24.3, 18.2% and 8.8 ns at a bias voltage 31.0 V, respectively. The flood histogram quality was also evaluated by using a 10 × 10 array of 1 mm × 1 mm × 10 mm polished LSO crystals and a 10 × 10 array of 0.7 mm × 0.7 mm × 20 mm unpolished LSO crystals to determine the smallest crystal size resolvable. These studies showed that the high spatial resolution of the PS-SSPM was preserved allowing for 0.7 mm crystals to be identified. These results show that the capacitive charge-division analog signal processing method can significantly reduce the number of electronic channels, from 20 to 5, while retaining the

  14. Betabox: a beta particle imaging system based on a position sensitive avalanche photodiode

    PubMed Central

    Dooraghi, AA; Vu, NT; Silverman, RW; Farrell, R; Shah, KS; Wang, J; Heath, JR; Chatziioannou, AF

    2013-01-01

    A beta camera has been developed that allows planar imaging of the spatial and temporal distribution of beta particles using a 14 × 14 mm2 position sensitive avalanche photodiode (PSAPD). This camera system, which we call Betabox, can be directly coupled to microfluidic chips designed for cell incubation or other biological applications. Betabox allows for imaging the cellular uptake of molecular imaging probes labeled with charged particle emitters such as 18F inside these chips. In this work, we investigate the quantitative imaging capabilities of Betabox for 18F beta particles, in terms of background rate, efficiency, spatial resolution, and count rate. Measurements of background and spatial resolution are considered both at room temperature (21 °C ± 1 °C) and at an elevated operating temperature (37 °C ± 1 °C), as is often required for biological assays. The background rate measured with a 4 keV energy cutoff is below 2 cph mm−2 at both 21 and 37 °C. The absolute efficiency of Betabox for the detection of 18F positron sources in contact with a PSAPD with the surface passivated from ambient light and damage is 46% ± 1%. The lower detection limit is estimated using the Rose Criterion to be 0.2 cps mm−2 for 1 min acquisitions and a 62 × 62 µm2 pixel size. The upper detection limit is approximately 21 000 cps. The spatial resolution at both 21 and 37 °C ranges from 0.4 mm FWHM at the center of the field of view (FOV), and degrades to 1 mm at a distance of 5 mm away from center yielding a useful FOV of approximately 10 × 10 mm2. We also investigate the effects on spatial resolution and sensitivity that result from the use of a polymer based microfluidic chip. For these studies we place varying layers of low-density polyethylene (LDPE) between the detector and the source and find that the spatial resolution degrades by ~180 µm for every 100 µm of LDPE film. Sensitivity is reduced by half with the inclusion of ~200 µm of additional LDPE film

  15. Betabox: a beta particle imaging system based on a position sensitive avalanche photodiode

    NASA Astrophysics Data System (ADS)

    Dooraghi, A. A.; Vu, N. T.; Silverman, R. W.; Farrell, R.; Shah, K. S.; Wang, J.; Heath, J. R.; Chatziioannou, A. F.

    2013-06-01

    A beta camera has been developed that allows planar imaging of the spatial and temporal distribution of beta particles using a 14 × 14 mm2 position sensitive avalanche photodiode (PSAPD). This camera system, which we call Betabox, can be directly coupled to microfluidic chips designed for cell incubation or other biological applications. Betabox allows for imaging the cellular uptake of molecular imaging probes labeled with charged particle emitters such as 18F inside these chips. In this work, we investigate the quantitative imaging capabilities of Betabox for 18F beta particles, in terms of background rate, efficiency, spatial resolution, and count rate. Measurements of background and spatial resolution are considered both at room temperature (21 °C ± 1 °C) and at an elevated operating temperature (37 °C ± 1 °C), as is often required for biological assays. The background rate measured with a 4 keV energy cutoff is below 2 cph mm-2 at both 21 and 37 °C. The absolute efficiency of Betabox for the detection of 18F positron sources in contact with a PSAPD with the surface passivated from ambient light and damage is 46% ± 1%. The lower detection limit is estimated using the Rose Criterion to be 0.2 cps mm-2 for 1 min acquisitions and a 62 × 62 µm2 pixel size. The upper detection limit is approximately 21 000 cps. The spatial resolution at both 21 and 37 °C ranges from 0.4 mm FWHM at the center of the field of view (FOV), and degrades to 1 mm at a distance of 5 mm away from center yielding a useful FOV of approximately 10 × 10 mm2. We also investigate the effects on spatial resolution and sensitivity that result from the use of a polymer based microfluidic chip. For these studies we place varying layers of low-density polyethylene (LDPE) between the detector and the source and find that the spatial resolution degrades by ˜180 µm for every 100 µm of LDPE film. Sensitivity is reduced by half with the inclusion of ˜200 µm of additional LDPE film. Lastly

  16. Estimation of Compton imager using single 3D position-sensitive LYSO scintillator: Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Lee, Taewoong; Lee, Hyounggun; Kim, Younghak; Lee, Wonho

    2017-07-01

    The performance of a Compton imager using a single three-dimensional position-sensitive LYSO scintillator detector was estimated using a Monte Carlo simulation. The Compton imager consisted of a single LYSO scintillator with a pixelized structure. The size of the scintillator and each pixel were 1.3 × 1.3 × 1.3 cm3 and 0.3 × 0.3 × 0.3 cm3, respectively. The order of γ-ray interactions was determined based on the deposited energies in each detector. After the determination of the interaction sequence, various types of reconstruction algorithms such as simple back-projection, filtered back-projection, and list-mode maximum-likelihood expectation maximization (LM-MLEM) were applied and compared with each other in terms of their angular resolution and signal-to-noise ratio (SNR) for several γ-ray energies. The LM-MLEM reconstruction algorithm exhibited the best performance for Compton imaging in maintaining high angular resolution and SNR. The two sources of 137Cs (662 keV) could be distinguishable if they were more than 17° apart. The reconstructed Compton images showed the precise position and distribution of various radiation isotopes, which demonstrated the feasibility of the monitoring of nuclear materials in homeland security and radioactive waste management applications.

  17. Rapid Flow Analysis Studies with Spectroscopic Detectors.

    NASA Astrophysics Data System (ADS)

    Thalib, Amlius

    A rapid flow analysis study based on segmented flow and flow injection principles is described in this thesis. The main objective of this study was to establish the response characteristics in continuous flow analysis systems in order to improve sampling rates with several types of spectroscopic detectors. It was found from flame photometric studies that non-segmented flowing streams are applicable to rapid flow analysis with automatic sample aspiration. Calcium was used as a typical example and determined at sampling rates up to 360 h('-1) with a detection limit of 0.05 mg L(' -1). A rapid flow system is reported using direct aspiration for AAS analysis with both manual injection and automatic aspiration techniques, and found to give sampling rates of up to 600-720 samples h('-1). Speed of analysis was reduced by about 50% when using an external peristaltic pump in the flow system design, due to increased sample dispersion. A novel aspect of a rapid flow injection approach reported with ICPAES detection includes the method of injecting samples via a peristaltic pump with simultaneous computer data processing. Determination of serum cations (Na, K, Ca, Mg and Fe) was demonstrated as an example of an application of the technique at sampling rates of 240 h('-1). Precision and detection limits for 13 elements in a single standard solution are reported. The use of automated aspiration sampling is also reported in this method for comparison. Further studies on flow characteristics were carried out by a combination of the rapid flow system with very short sampling times as low as 2 seconds using UV-visible spectrophotometric detection. Analysis of human blood serum samples was used as an example where total protein and inorganic phosphate were determined at sampling rates of 240 h('-1) and 360 h('-1) respectively. The novel aspects of the results from these studies include the very rapid sample throughput developed with simple and inexpensive experimental approaches in

  18. Use of a YAP:Ce matrix coupled to a position-sensitive photomultiplier for high resolution positron emission tomography

    SciTech Connect

    Del Guerra, A.; Zavattini, G. |; Notaristefani, F. de |; Di Domenico, G. |; Giganti, M.; Piffanelli, A.; Pani, R.; Turra, A.

    1996-06-01

    A new scintillation detector system has been designed for application in high resolution Positron Emission Tomography (PET). The detector is a bundle of small YAlO{sub 3}:Ce (YAP) crystals closely packed (0.2 x 0.2 x 3.0 cm{sup 3}), coupled to a position sensitive photomultiplier tube (PSPMT). The preliminary results obtained for spatial resolution, time resolution, energy resolution and efficiency of two such detectors working in coincidence are presented. These are 1.2 mm for the FWHM spatial resolution, 2.0 ns for the FWHM time resolution and 20% for the FWHM energy resolution at 511 keV. The measured efficiency is (44 {+-} 3)% with a 150 keV threshold and (20 {+-} 2)% with a 300 keV threshold.

  19. Detector to detector corrections: a comprehensive experimental study of detector specific correction factors for beam output measurements for small radiotherapy beams.

    PubMed

    Azangwe, Godfrey; Grochowska, Paulina; Georg, Dietmar; Izewska, Joanna; Hopfgartner, Johannes; Lechner, Wolfgang; Andersen, Claus E; Beierholm, Anders R; Helt-Hansen, Jakob; Mizuno, Hideyuki; Fukumura, Akifumi; Yajima, Kaori; Gouldstone, Clare; Sharpe, Peter; Meghzifene, Ahmed; Palmans, Hugo

    2014-07-01

    The aim of the present study is to provide a comprehensive set of detector specific correction factors for beam output measurements for small beams, for a wide range of real time and passive detectors. The detector specific correction factors determined in this study may be potentially useful as a reference data set for small beam dosimetry measurements. Dose response of passive and real time detectors was investigated for small field sizes shaped with a micromultileaf collimator ranging from 0.6 × 0.6 cm(2) to 4.2 × 4.2 cm(2) and the measurements were extended to larger fields of up to 10 × 10 cm(2). Measurements were performed at 5 cm depth, in a 6 MV photon beam. Detectors used included alanine, thermoluminescent dosimeters (TLDs), stereotactic diode, electron diode, photon diode, radiophotoluminescent dosimeters (RPLDs), radioluminescence detector based on carbon-doped aluminium oxide (Al2O3:C), organic plastic scintillators, diamond detectors, liquid filled ion chamber, and a range of small volume air filled ionization chambers (volumes ranging from 0.002 cm(3) to 0.3 cm(3)). All detector measurements were corrected for volume averaging effect and compared with dose ratios determined from alanine to derive a detector correction factors that account for beam perturbation related to nonwater equivalence of the detector materials. For the detectors used in this study, volume averaging corrections ranged from unity for the smallest detectors such as the diodes, 1.148 for the 0.14 cm(3) air filled ionization chamber and were as high as 1.924 for the 0.3 cm(3) ionization chamber. After applying volume averaging corrections, the detector readings were consistent among themselves and with alanine measurements for several small detectors but they differed for larger detectors, in particular for some small ionization chambers with volumes larger than 0.1 cm(3). The results demonstrate how important it is for the appropriate corrections to be applied to give

  20. Fast Optical Position-Sensitive Detector for McPherson ESCA-36.

    DTIC Science & Technology

    1983-06-01

    KALINOWSKI, * L. E. TRIBBLE, and L. U. TOLENTINO * Chemistry and Physics Laboratory Laboratory OperationsIThe Aerospace Corporation El Segundo, Calif. 90245...Angeles Air Force Station P.O. Box 92960, Worldway Postal Center Los Angeles, Calif. 90009 -,z-I This report was submitted by The Aerospace Corporation ...Angeles, CA 90009. It was reviewed and approved for The Aerospace Corporation by S. Feuerstein, Director, Chemistry and Physics Laboratory. 2nd Lt Ken

  1. Three-dimensional, position-sensitive radiation detection

    DOEpatents

    He, Zhong; Zhang, Feng

    2010-04-06

    Disclosed herein is a method of determining a characteristic of radiation detected by a radiation detector via a multiple-pixel event having a plurality of radiation interactions. The method includes determining a cathode-to-anode signal ratio for a selected interaction of the plurality of radiation interactions based on electron drift time data for the selected interaction, and determining the radiation characteristic for the multiple-pixel event based on both the cathode-to-anode signal ratio and the electron drift time data. In some embodiments, the method further includes determining a correction factor for the radiation characteristic based on an interaction depth of the plurality of radiation interactions, a lateral distance between the selected interaction and a further interaction of the plurality of radiation interactions, and the lateral positioning of the plurality of radiation interactions.

  2. PMT overshoot study for the JUNO prototype detector

    NASA Astrophysics Data System (ADS)

    Luo, Feng-Jiao; Heng, Yue-Kun; Wang, Zhi-Min; Wang, Pei-Liang; Qin, Zhong-Hua; Xu, Mei-Hang; Liao, Dong-Hao; Zhang, Hai-Qiong; Huang, Yong-Bo; Lei, Xiang-Cui; Qian, Sen; Liu, Shu-Lin; Chen, Yuan-Bo; Wang, Yi-Fang

    2016-09-01

    The quality of PMT signals is crucial for large-size and high-precision neutrino experiments, but most of these experiments are affected by the overshoot of PMT signals from the positive HV-single cable scheme. Overshoot affects the trigger, dead time and charge measurement from a detector. For the JUNO prototype detector, we have performed a detailed study and calculation on PMT signal overshoot to control the ratio of overshoot to signal amplitude to ∼1%, with no effect on other PMT parameters. Supported by Strategic Priority Research Program A-JUNO, High Energy Physics Experiment and Detector R&D and National Natural Science Foundation of China

  3. Detector-accelerator interface studies at the Tevatron

    SciTech Connect

    Drozhdin, A.I.; Mokhov, N.V.

    1998-04-10

    A summary of studies is presented towards minimization of beam loss in the critical locations at the Fermilab Tevatron to reduce background rates in the collider detectors and to protect machine components. Based on detailed Monte-Carlo simulations, measures have been proposed and incorporated in the machine to reduce accelerator-related instantaneous and residual background levels in the D0 and CDF detectors. Measurements performed are in good agreement with the predictions. Most recent results on acceptance and background rates in the D0 and CDF forward detectors are presented and discussed in detail.

  4. Breakdown Limit Studies in High-Rate Gaseous Detectors

    NASA Technical Reports Server (NTRS)

    Ivaniouchenkov, Yu; Fonte, P.; Peskov, V.; Ramsey, B. D.

    1999-01-01

    We report results from a systematic study of breakdown limits for novel high-rate gaseous detectors: MICROMEGAS, CAT and GEM, together with more conventional devices such as thin-gap parallel-mesh chambers and high-rate wire chambers. It was found that for all these detectors, the maximum achievable pin, before breakdown appears, drops dramatically with incident flux, and is sometimes inversely proportional to it. Further, in the presence of alpha particles, typical of the breakgrounds in high-energy experiments, additional gain drops of 1-2 orders of magnitude were observed for many detectors. It was found that breakdowns at high rates occur through what we have termed an "accumulative" mechanism, which does not seem to have been previously reported in the literature. Results of these studies may help in choosing the optimum detector for given experimental conditions.

  5. MCNPX Simulation Study of STRAW Neutron Detectors

    SciTech Connect

    Sanjoy Mukhopadhyay, Richard Maurer, Stephen Mitchell

    2010-01-08

    A novel prototype fission meter is being designed at National Security Technologies, LLC, using a thin uniform coating (only 1 micron thick) of {sup 10}B as a neutron converter inside a large array of thin (4 mm diameter) copper tubes. The copper tubes are only 2 mils thick, and each holds the stretched anode wire under tension and high voltage. The tubes are filled with proportional counter gas (a mixture of 90%/10% of Ar/CO{sub 2}). The tubes operate in proportional counter mode and attract mobile charged particles ({alpha}'s) created in the nuclear interaction {sup 10}B(n, {sup 4}He){sup 7}Li. However, a single tube has about 1/7th the sensitivity of a {sup 3}He tube. Modeling is required to determine if enough such tubes could be placed in a neutron detection assembly of the current size to give comparable sensitivity to {sup 3}He. Detectors lined with {sup 10}B lie between {sup 3}He and {sup 10}BF{sub 3} proportional counters and fission chambers in terms of neutron detection efficiency and gamma ray insensitivity. The mean free path of thermal neutrons in {sup 10}B is about 18 {micro}m. It takes about 60 {micro}m of {sup 10}B layer to completely stop thermal neutrons, but the energetic {alpha}-particles generated in the reaction have a range of only 3.3 {micro}m in {sup 10}B environment - hence the thin layer of boron coating on the copper tube. The prototype design is shown in Figure 1. It consists of two panels of three staggered rows of 500-mm-long, 4-mm-diameter straws, with 20 in each row, embedded in 30-mm-thick high density polyethylene (HDPE). The project demonstrates a new application of thin neutron and gamma converter technique (1 micron thin {sup 10}B coated copper tube). It exploits fast timing from multiple straw detectors to count multiplicity of both gamma and neutrons from fissioning materials. The objective is to find a near-term replacement of {sup 3}He gas in neutron detection and measurement (with a very large neutron detection area). All

  6. Study of the spatial resolution for binary readout detectors

    NASA Astrophysics Data System (ADS)

    Yonamine, R.; Maerschalk, T.; Lentdecker, G. De

    2016-07-01

    Often the binary readout is proposed for high granularity detectors to reduce the generated data volume to be readout at the price of a somewhat reduced spatial resolution compared to an analogue readout. We have been studying single hit resolutions obtained with a binary readout using simulations as well as analytical approaches. In this note we show that the detector geometry could be optimized to offer an equivalent spatial resolution than with an analogue readout.

  7. A Study of a Mini-Drift GEM Tracking Detector

    SciTech Connect

    Azmoun, B.; DiRuzza, B.; Franz, A.; Kiselev, A.; Pak, R.; Phipps, M.; Purschke, M. L.; Woody, C.

    2016-06-22

    In this paper, a GEM tracking detector with an extended drift region has been studied as part of an effort to develop new tracking detectors for future experiments at RHIC and for the Electron Ion Collider that is being planned for BNL or JLAB. The detector consists of a triple GEM stack with a 1.6 cm drift region that was operated in a mini TPC type configuration. Both the position and arrival time of the charge deposited in the drift region were measured on the readout plane which allowed the reconstruction of a short vector for the track traversing the chamber. The resulting position and angle information from the vector could then be used to improve the position resolution of the detector for larger angle tracks, which deteriorates rapidly with increasing angle for conventional GEM tracking detectors using only charge centroid information. Two types of readout planes were studied. One was a COMPASS style readout plane with 400 μm pitch XY strips and the other consisted of 2 × 10 mm2 chevron pads. The detector was studied in test beams at Fermilab and CERN, along with additional measurements in the lab, in order to determine its position and angular resolution for incident track angles up to 45 degrees. Several algorithms were studied for reconstructing the vector using the position and timing information in order to optimize the position and angular resolution of the detector for the different readout planes. Finally, applications for large angle tracking detectors at RHIC and EIC are also discussed.

  8. A Study of a Mini-Drift GEM Tracking Detector

    SciTech Connect

    Azmoun, B.; DiRuzza, B.; Franz, A.; Kiselev, A.; Pak, R.; Phipps, M.; Purschke, M. L.; Woody, C.

    2016-06-22

    In this paper, a GEM tracking detector with an extended drift region has been studied as part of an effort to develop new tracking detectors for future experiments at RHIC and for the Electron Ion Collider that is being planned for BNL or JLAB. The detector consists of a triple GEM stack with a 1.6 cm drift region that was operated in a mini TPC type configuration. Both the position and arrival time of the charge deposited in the drift region were measured on the readout plane which allowed the reconstruction of a short vector for the track traversing the chamber. The resulting position and angle information from the vector could then be used to improve the position resolution of the detector for larger angle tracks, which deteriorates rapidly with increasing angle for conventional GEM tracking detectors using only charge centroid information. Two types of readout planes were studied. One was a COMPASS style readout plane with 400 μm pitch XY strips and the other consisted of 2 × 10 mm2 chevron pads. The detector was studied in test beams at Fermilab and CERN, along with additional measurements in the lab, in order to determine its position and angular resolution for incident track angles up to 45 degrees. Several algorithms were studied for reconstructing the vector using the position and timing information in order to optimize the position and angular resolution of the detector for the different readout planes. Finally, applications for large angle tracking detectors at RHIC and EIC are also discussed.

  9. A Study of a Mini-Drift GEM Tracking Detector

    DOE PAGES

    Azmoun, B.; DiRuzza, B.; Franz, A.; ...

    2016-06-22

    In this paper, a GEM tracking detector with an extended drift region has been studied as part of an effort to develop new tracking detectors for future experiments at RHIC and for the Electron Ion Collider that is being planned for BNL or JLAB. The detector consists of a triple GEM stack with a 1.6 cm drift region that was operated in a mini TPC type configuration. Both the position and arrival time of the charge deposited in the drift region were measured on the readout plane which allowed the reconstruction of a short vector for the track traversing themore » chamber. The resulting position and angle information from the vector could then be used to improve the position resolution of the detector for larger angle tracks, which deteriorates rapidly with increasing angle for conventional GEM tracking detectors using only charge centroid information. Two types of readout planes were studied. One was a COMPASS style readout plane with 400 μm pitch XY strips and the other consisted of 2 × 10 mm2 chevron pads. The detector was studied in test beams at Fermilab and CERN, along with additional measurements in the lab, in order to determine its position and angular resolution for incident track angles up to 45 degrees. Several algorithms were studied for reconstructing the vector using the position and timing information in order to optimize the position and angular resolution of the detector for the different readout planes. Finally, applications for large angle tracking detectors at RHIC and EIC are also discussed.« less

  10. Gas microstrip detectors based on flexible printed circuit

    SciTech Connect

    Salomon, M.; Crowe, K.; Faszer, W.; Lindsay, P.; Curran Maier, J.M.

    1995-09-01

    Microstrip Gas Detectors (MSGC`s) were introduced some years ago as position sensitive detectors capable of operating at very high rates. The authors have studied the properties of a new type of Gas Microstrip Counter built using flexible printed circuit technology. They describe the manufacturing procedures, the assembly of the device, as well as its operation under a variety of conditions, gases and types of radiation. They also describe two new passivation materials, tantalum and niobium, which produce effective surfaces.

  11. Development of Position-Sensitive Magnetic Calorimeters for X-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Bandler, SImon; Stevenson, Thomas; Hsieh, Wen-Ting

    2011-01-01

    Metallic magnetic calorimeters (MMC) are one of the most promising devices to provide very high energy resolution needed for future astronomical x-ray spectroscopy. MMC detectors can be built to large detector arrays having thousands of pixels. Position-sensitive magnetic (PoSM) microcalorimeters consist of multiple absorbers thermally coupled to one magnetic micro calorimeter. Each absorber element has a different thermal coupling to the MMC, resulting in a distribution of different pulse shapes and enabling position discrimination between the absorber elements. PoSMs therefore achieve the large focal plane area with fewer number of readout channels without compromising spatial sampling. Excellent performance of PoSMs was achieved by optimizing the designs of key parameters such as the thermal conductance among the absorbers, magnetic sensor, and heat sink, as well as the absorber heat capacities. Micro fab ri - cation techniques were developed to construct four-absorber PoSMs, in which each absorber consists of a two-layer composite of bismuth and gold. The energy resolution (FWHM full width at half maximum) was measured to be better than 5 eV at 6 keV x-rays for all four absorbers. Position determination was demonstrated with pulse-shape discrimination, as well as with pulse rise time. X-ray microcalorimeters are usually designed to thermalize as quickly as possible to avoid degradation in energy resolution from position dependence to the pulse shapes. Each pixel consists of an absorber and a temperature sensor, both decoupled from the cold bath through a weak thermal link. Each pixel requires a separate readout channel; for instance, with a SQUID (superconducting quantum interference device). For future astronomy missions where thousands to millions of resolution elements are required, having an individual SQUID readout channel for each pixel becomes difficult. One route to attaining these goals is a position-sensitive detector in which a large continuous or

  12. Position-sensitive radiation monitoring (surface contamination monitor). Innovative technology summary report

    SciTech Connect

    Not Available

    1999-06-01

    The Shonka Research Associates, Inc. Position-Sensitive Radiation Monitor both detects surface radiation and prepares electronic survey map/survey report of surveyed area automatically. The electronically recorded map can be downloaded to a personal computer for review and a map/report can be generated for inclusion in work packages. Switching from beta-gamma detection to alpha detection is relatively simple and entails moving a switch position to alpha and adjusting the voltage level to an alpha detection level. No field calibration is required when switching from beta-gamma to alpha detection. The system can be used for free-release surveys because it meets the federal detection level sensitivity limits requires for surface survey instrumentation. This technology is superior to traditionally-used floor contamination monitor (FCM) and hand-held survey instrumentation because it can precisely register locations of radioactivity and accurately correlate contamination levels to specific locations. Additionally, it can collect and store continuous radiological data in database format, which can be used to produce real-time imagery as well as automated graphics of survey data. Its flexible design can accommodate a variety of detectors. The cost of the innovative technology is 13% to 57% lower than traditional methods. This technology is suited for radiological surveys of flat surfaces at US Department of Energy (DOE) nuclear facility decontamination and decommissioning (D and D) sites or similar public or commercial sites.

  13. Reciprocal space mapping of epitaxial materials using position-sensitive x-ray detection

    SciTech Connect

    Lee, S.R.; Doyle, B.L.; Drummond, T.J.; Medernach, J.W.; Schneider, R.P. Jr.

    1994-10-01

    Reciprocal space mapping can be efficiently carried out using a position-sensitive x-ray detector (PSD) coupled to a traditional double-axis diffractometer. The PSD offers parallel measurement of the total scattering angle of all diffracted x-rays during a single rocking-curve scan. As a result, a two-dimensional reciprocal space map can be made in a very short time similar to that of a one-dimensional rocking-curve scan. Fast, efficient reciprocal space mapping offers numerous routine advantages to the x-ray diffraction analyst. Some of these advantages are the explicit differentiation of lattice strain from crystal orientation effects in strain-relaxed heteroepitaxial layers; the nondestructive characterization of the size, shape and orientation of nanocrystalline domains in ordered-alloy epilayers; and the ability to measure the average size and shape of voids in porous epilayers. Here, the PSD-based diffractometer is described, and specific examples clearly illustrating the advantages of complete reciprocal space analysis are presented.

  14. Single-Photon Computed Tomography With Large Position-Sensitive Phototubes*

    NASA Astrophysics Data System (ADS)

    Feldmann, John; Ranck, Amoreena; Saunders, Robert S.; Welsh, Robert E.; Bradley, Eric L.; Saha, Margaret S.; Kross, Brian; Majewski, Stan; Popov, Vladimir; Weisenberger, Andrew G.; Wojcik, Randolph

    2000-10-01

    Position-sensitive photomultiplier tubes (PSPMTs) coupled to pixelated CsI(Tl) scintillators have been used with parallel-hole collimators to view the metabolism in small animals of radiopharmaceuticals tagged with ^125I. We report here our preliminary results analyzed using a tomography program^1 written in IDL programming language. The PSPMTs are mounted on a rotating gantry so as to view the subject animal from any azimuth. Preliminary results to test the tomography algorithm have been obtained by placing a variety of plastic mouse-brain phantoms (loaded with Na^125I) in front of one of the detectors and rotating the phantom in steps through 360 degrees. Results of this simulation taken with a variety of collimator hole sizes will be compared and discussed. Extentions of this technique to the use of very small PSPMTs (Hamamatsu M-64) which are capable of a very close approach to those parts of the animal of greatest interest will be described. *Supported in part by The Department of Energy, The National Science Foundation, The American Diabetes Association, The Howard Hughes Foundation and The Jeffress Trust. 1. Tomography algorithm kindly provided by Dr. S. Meikle of The Royal Prince Albert Hospital, Sydney, Australia

  15. Development of a novel radiation imaging detector system for in vivo gene imaging in small animal studies

    SciTech Connect

    Weisenberger, A.G. |; Bradley, E.L.; Saha, M.S.; Majewski, S.

    1998-06-01

    The authors report preliminary results from a prototype of radiation imaging technology which takes advantage of the emission properties of the radioisotope iodine 125 ({sup 125}I) as the probe. The detector system utilizes crystal scintillators and a position sensitive photomultiplier tube. Iodine 125 decays via electron capture emitting a 35-keV gamma ray with the prompt emission of several 27-32-keV {Kappa} {alpha} and {Kappa} {beta} shell X rays. Because of this, a coincidence condition can be set to detect the {sup 125}I decay, thus reducing background radiation contribution to the image. The prototype detector the authors report has a limited sensitivity and detection area because of the size of the scintillators and photomultiplier tubes, yet it performed well enough to demonstrate the viability of this method for imaging {sup 125}I in a mouse. Mouse imaging studies of iodine uptake by the thyroid and melatonin binding have been done with this detector system using doses of {sup 125}I alone or attached to the melatonin. Many studies in molecular biology follow the expression and regulation of a gene at different stages of an organism`s development or under different physiological conditions. Molecular biology research could benefit from this detection system by utilizing {sup 125}I-labeled gene probes.

  16. A microstrip detector with delay line readout

    SciTech Connect

    Barbosa, A.F. , BP 220, 38043 Grenoble CNPq Riekel, C.; Wattecamps, P. , BP 220, 38043 Grenoble )

    1992-01-01

    Principal limitations of position sensitive gasfilled detectors for x-ray synchrotron radiation applications are the counting rate and the positional resolution. Improvements in both areas are expected with microstrip technology. First results of a linear position sensitive microstrip detector with delay line readout are shown, and the possibility to achieve two-dimensional localization is evaluated.

  17. Simulation study of a 'fission electron-collection' neutron detector

    SciTech Connect

    Wang Dong; Zhang Chuanfei

    2015-07-01

    In this work, a 'fission electron-collection' neutron detector was studied using the Monte Carlo method. The detector consists of two metal electrodes mounted in a vacuum, named coated and collection electrodes, respectively. The first electrode is coated with triuranium octoxide. The detector uses the 'fission electron-collection' technique, which does not need an intermediate material but directly collects electrons from the coating. Such a detector can realize a flat energy response and a fast time response, both of which are important in the fluence measurement of pulsed neutron sources. In this paper, the physical processes of detection are presented, as well as Monte Carlo simulation studies using the Geant4 toolkit. From the results, the sensitivity of the detector is approximately 1.5 x 10{sup -21} [C/(n/cm{sup 2})], and the FWHM of response function is 2.5 nanoseconds. Additionally, the characterization of escaping electrons is also presented, and the sensitivity of the detector is determined for various coating thicknesses. (authors)

  18. Background Studies for the pn-CCD Detector of CAST

    SciTech Connect

    Rodriguez, A.; Beltran, B.; Cebrian, S.; Gomez, H.; Irastorza, I. G.; Luzon, G.; Morales, J.; Ruz, J.; Villar, J. A.; Hartmann, R.; Kotthaus, R.; Klose, C.; Kuster, M.; Strueder, L.

    2007-03-28

    The CERN Axion Solar Telescope (CAST) experiment searches for axions from the Sun converted into photons with energies up to around 10 keV via the inverse Primakoff effect in the high magnetic field of a superconducting Large Hadron Collider (LHC) prototype magnet. A backside illuminated pn-CCD detector in conjunction with an X-ray mirror optics is one of the three detectors used in CAST to register the expected photon signal. Since this signal is very rare a detailed study of the detector background has been undertaken with the aim to understand and further reduce the background level of the detector. The analysis is based on measured data taken during the data taking period of 2003 and 2004 of CAST and on Monte Carlo simulations of background with different origin. The background study performed for this detector show that the level of background (8.00{+-}0.07)x10-5 counts cm-2 s-1 keV-1 between 1 and 7 keV is dominated by the external gamma background due to natural activities at the experimental site, while radioactive impurities in the detector itself and cosmic neutrons contribute with a smaller fraction.

  19. Imaging and Timing Performance of 1cm × 1cm Position-sensitive Solid-state Photomultiplier

    PubMed Central

    Schmall, J.; Stapels, C.; Christian, J.; Cherry, S.; Squillante, M. R.; Shah, K.

    2014-01-01

    We have designed and built a large-area 1cm × 1cm position-sensitive solid-state photomultiplier (PS-SSPM) for use in detector design for medical imaging applications. Our new large-area PS-SSPM concept implements resistive network between the micro-pixels, which are photodiodes operated in Geiger mode, called Geiger Photodiodes (GPDs), to provide continuous position sensitivity. Here we present imaging and timing performance of the large-area PS-SSPM for different temperatures and operating biases to find the optimum operating parameters for the device in imaging applications. A detector module was built by coupling a polished 8×8 LYSO array, with 1×1×20 mm3 elements, to a 1×1 cm2 PS-SSPM. Flood images recorded at room temperature show good crystal separation as all 64 elements were separated from each other. Cooling the device at 10 °C showed significant improvement. The device optimum bias voltage was ~4.5V over breakdown voltage. The coincidence timing resolution was improved significantly by increasing the operating bias, as well as by lowering the temperature to 0 °C. Results show excellent imaging performance and good timing response with a large-area PS-SSPM device. PMID:25540669

  20. A study of hadronic events with the L3 detector

    NASA Astrophysics Data System (ADS)

    Ostonen, Rego

    1997-11-01

    This thesis summarises some experimental results from a study of hadronic events using the L3 detector at LEP (Large Electron-Positron Collider, CERN). The second part of the thesis is devoted to the development of new detector technologies, attention is concentrated to the silicon microstrip detectors. At center-of-mass energies close to 91.2 GeV, a study of hadronic Z decays with hard isolated photons in the final state was performed. The aim of the study was to search for a possible Higgs boson signal in the processes e+e- -->H0 g-->qqg and e+e- -->Z* H0-->qqg g . The Standard Model predictions for these cross sections are very low, however some Standard Model extensions predict significant enhancements. No signal of the Higgs boson was observed and the results were used to set an upper limit for the cross sections of the corresponding processes. At center-of-mass energies 161 GeV<s<172GeV GeV a measurement of the hadron cross section, s(e+e- -->qq (g)) , was performed. Hadronic events, where the center-of-mass energy of the e+e- collision is twice the beam energy are called high energy events. In addition, due to the presence of the Z resonance at 91 GeV, initial state radiation can lower the center-of-mass energy of the e+e- collision to values close to mZ, such events are called return to Z events. The hadron production cross section was measured for the total event sample, including return to Z events, as well as for the high energy sample, excluding return to Z events. All measurements agree with the Standard Model predictions. The last two publications of the thesis summarise the beam test results of silicon microstrip detector prototypes, originally designed for the tracker upgrade of the L3 detector at LEP in preparation for the LEP2 running. The 60 cm long DC-coupled 50 μm strip pitch detector was manufactured at the Technical Research Center of Finland (VTT Electronics) and beam tested at CERN using the 50 GeV electron beam from

  1. Optical Studies on Antimonide Superlattice Infrared Detector Material

    NASA Technical Reports Server (NTRS)

    Hoglund, Linda; Soibel, Alexander; Hill, Cory J.; Ting, David Z.; Khoshakhlagh, Arezou; Liao, Anna; Keo, Sam; Lee, Michael C.; Nguyen, Jean; Mumolo, Jason M.; hide

    2010-01-01

    In this study the material quality and optical properties of type II InAs/GaSb superlattices are investigated using transmission and photoluminescence (PL) spectroscopy. The influence of the material quality on the intensity of the luminescence and on the electrical properties of the detectors is studied and a good correlation between the photodetector current-voltage (IV) characteristics and the PL intensity is observed. Studies of the temperature dependence of the PL reveal that Shockley-Read-Hall processes are limiting the minority carrier lifetime in both the mid-IR wavelength and the long-IR wavelength detector material studied. These results demonstrate that PL spectroscopy is a valuable tool for optimization of infrared detectors.

  2. The neutron moderated detector and groundbased cosmic ray modulation studies

    NASA Technical Reports Server (NTRS)

    Stoker, P. H.; Raubenheimer, B. C.

    1985-01-01

    Reports appear on modulation studies with the neutron monitor without lead. Some of these studies cast doubt on the reliability of this detector. The stability of the neutron moderated detector (NMD) at Sanae, Antarctic is discussed. The barometric coeficient of the 4NMD for epoch 1976 appears not to differ statistically from the 0.73%/mb of the 3NM64. The monthly averaged hourly counting rate of our 4NMD and 3NM64 correlates very well (correlation coefficient: 98%) over the years from 1974-1984, with the 4NMD showing a 8% larger long term modulation effect than the 3NM64, indicating a difference in sensitivities of the two detectors. From this difference in sensitivities spectra of ground level solar proton events and modulation functions of Forbush decreases are deduced.

  3. Proton Transfer Reactions Studied Using the VANDLE Neutron Detector Array

    NASA Astrophysics Data System (ADS)

    Thornsberry, C. R.; Burcher, S.; Gryzwacz, R.; Jones, K. L.; Paulauskas, S. V.; Smith, K.; Vostinar, M.; Allen, J.; Bardayan, D. W.; Blankstein, D.; Deboer, J.; Hall, M.; O'Malley, P. D.; Reingold, C.; Tan, W.; Cizewski, J. A.; Lepailleur, A.; Walter, D.; Febbraro, M.; Pain, S. D.; Marley, S. T.

    2016-09-01

    Proton transfer reactions, such as (d,n), are powerful tools for the study of single particle proton states of exotic nuclei. Measuring the outgoing neutron allows for the extraction of spectroscopic information from the recoil nucleus. With the development of new radioactive ion beam facilities, such as FRIB in the U.S., comes the need for new tools for the study of reactions involving radioactive nuclei. Neutron detectors, such as VANDLE, are sensitive to gamma rays in addition to neutrons. This results in high background rates for measurements with high external trigger rates. The use of discriminating recoil particle detectors, such as phoswich detectors, allow for the selection of a clean recoil tag by separating the recoil nucleus of interest from unreacted RIB components. Developments of low energy proton transfer measurements in inverse kinematics and recent (d,n) results will be presented. This work supported in part by the U.S. Department of Energy and the National Science Foundation.

  4. Detector to detector corrections: A comprehensive experimental study of detector specific correction factors for beam output measurements for small radiotherapy beams

    SciTech Connect

    Azangwe, Godfrey Grochowska, Paulina; Izewska, Joanna; Meghzifene, Ahmed; Georg, Dietmar; Hopfgartner, Johannes; Lechner, Wolfgang; Mizuno, Hideyuki; Fukumura, Akifumi; Yajima, Kaori; Gouldstone, Clare; Sharpe, Peter; Palmans, Hugo

    2014-07-15

    Purpose: The aim of the present study is to provide a comprehensive set of detector specific correction factors for beam output measurements for small beams, for a wide range of real time and passive detectors. The detector specific correction factors determined in this study may be potentially useful as a reference data set for small beam dosimetry measurements. Methods: Dose response of passive and real time detectors was investigated for small field sizes shaped with a micromultileaf collimator ranging from 0.6 × 0.6 cm{sup 2} to 4.2 × 4.2 cm{sup 2} and the measurements were extended to larger fields of up to 10 × 10 cm{sup 2}. Measurements were performed at 5 cm depth, in a 6 MV photon beam. Detectors used included alanine, thermoluminescent dosimeters (TLDs), stereotactic diode, electron diode, photon diode, radiophotoluminescent dosimeters (RPLDs), radioluminescence detector based on carbon-doped aluminium oxide (Al{sub 2}O{sub 3}:C), organic plastic scintillators, diamond detectors, liquid filled ion chamber, and a range of small volume air filled ionization chambers (volumes ranging from 0.002 cm{sup 3} to 0.3 cm{sup 3}). All detector measurements were corrected for volume averaging effect and compared with dose ratios determined from alanine to derive a detector correction factors that account for beam perturbation related to nonwater equivalence of the detector materials. Results: For the detectors used in this study, volume averaging corrections ranged from unity for the smallest detectors such as the diodes, 1.148 for the 0.14 cm{sup 3} air filled ionization chamber and were as high as 1.924 for the 0.3 cm{sup 3} ionization chamber. After applying volume averaging corrections, the detector readings were consistent among themselves and with alanine measurements for several small detectors but they differed for larger detectors, in particular for some small ionization chambers with volumes larger than 0.1 cm{sup 3}. Conclusions: The results demonstrate

  5. Efficiency Studies for the new Muon Telescope Detector at STAR

    NASA Astrophysics Data System (ADS)

    Carson, Hannah; STAR Collaboration

    2013-10-01

    The Muon Telescope Detector (MTD) is a new detector subsystem in STAR at the Relativistic Heavy Ion Collider (RHIC). The MTD will contribute to studies of the matter being created in heavy-ion collisions by allowing measurements of the J/Psi meson and the different Upsilon states over a broad transverse momentum range via the reconstruction of their di-muon decays. Simulations to estimate the efficiency of the MTD for detecting muons were performed. The results of these simulations will be presented.

  6. Study of low multiplicity electron source LEETECH with diamond detector

    NASA Astrophysics Data System (ADS)

    Kubytskyi, V.; Krylov, V.; Bambade, P.; Cabouat, B.; Wicek, F.; Bogard, F.; Barsuk, S.; Rodin, V.; Burmistrov, L.; Bezshyyko, O.; Attie, D.; Colas, P.; Fedorchuk, O.; Golinka-Bezshyyko, L.; Lopez, R.; Monard, H.; Cayla, J.-N.; Sukhonos, D.; Titov, M.; Tomassini, D.; Variola, A.

    2017-02-01

    In this paper, we present experimental and numerical studies of the calibration of low-multiplicity electron source using signals from electrons incident on a diamond detector. The experiments were performed at the newly commissioned versatile LEETECH platform at the PHIL photoinjector facility at LAL. We show that with a single crystal CVD diamonds of 500 micrometers thickness, the energy losses from the first three electrons of 2.5–3 MeV are clearly resolved. The described technique can be used as a complementary approach for calibration of diamond detectors as well as for diagnostics of accelerated beam halos in a regime down to a few particles.

  7. Setup optimization toward accurate ageing studies of gas filled detectors

    NASA Astrophysics Data System (ADS)

    Abuhoza, A.; Schmidt, H. R.; Biswas, S.; Frankenfeld, U.; Hehner, J.; Schmidt, C. J.

    2013-08-01

    An infrastructure has been set up at the GSI detector laboratory to study the influence of construction materials on the ageing properties of gas filled detectors, such as multi-wire proportional chamber (MWPC), gas electron multiplier (GEM). Optimization of an ageing setup was performed by observing the variation of the normalized gain obtained using two identical MWPCs. An accuracy in the relative gain measurement below 1% has been achieved by monitoring environmental conditions and by systematic improvements of the measuring equipment. Ageing test of fiberglass G11 has been performed.

  8. Theory and Development of Position-Sensitive Quantum Calorimeters. Degree awarded by Stanford Univ.

    NASA Technical Reports Server (NTRS)

    Figueroa-Feliciano, Enectali; White, Nicholas E. (Technical Monitor)

    2001-01-01

    Quantum calorimeters are being developed as imaging spectrometers for future X-ray astrophysics observatories. Much of the science to be done by these instruments could benefit greatly from larger focal-plane coverage of the detector (without increasing pixel size). An order of magnitude more area will greatly increase the science throughput of these future instruments. One of the main deterrents to achieving this goal is the complexity of the readout schemes involved. We have devised a way to increase the number of pixels from the current baseline designs by an order of magnitude without increasing the number of channels required for readout. The instrument is a high energy resolution, distributed-readout imaging spectrometer called a Position-Sensitive Transition-Edge Sensor (POST). A POST is a quantum calorimeter consisting of two Transition-Edge Sensors (TESS) on the ends of a long absorber capable of one-dimensional imaging spectroscopy. Comparing rise time and energy information from the two TESS, the position of the event in the POST is determined. The energy of the event is inferred from the sum of the two pulses. We have developed a generalized theoretical formalism for distributed-readout calorimeters and apply it to our devices. We derive the noise theory and calculate the theoretical energy resolution of a POST. Our calculations show that a 7-pixel POST with 6 keV saturation energy can achieve 2.3 eV resolution, making this a competitive design for future quantum calorimeter instruments. For this thesis we fabricated 7- and 15-pixel POSTS using Mo/Au TESs and gold absorbers, and moved from concept drawings on scraps of napkins to a 32 eV energy resolution at 1.5 keV, 7-pixel POST calorimeter.

  9. Study of the anode plasma double layer: optogalvanic detectors

    SciTech Connect

    Gurlui, S.; Dimitriu, D.; Strat, M.; Strat, Georgeta

    2006-01-15

    The experimental and theoretical results show that the anode double layer (DL) is a very sensitive plasma formation suitable for fine optogalvanic studies. The obtained results demonstrate that the parameters of the oscillations sustained by a DL (frequency, amplitude) can be used as optogalvanic detectors.

  10. Silicon Detector Studies with an Interferometric Thickness Mapper

    NASA Technical Reports Server (NTRS)

    Milliken, B.; Leske, R. A.; Wiedenbeck, M. E.

    1995-01-01

    Cosmic ray isotopic composition studies aboard satellites are normally based on energy detection measurements which require a precise knowledge of matter thickness particle penetration. A laser- interferometer system has been developed to precisely map the thick- ness variations of large-area silicon detectors. Design, operation, and the data processing to derive thickness maps is described.

  11. Monte Carlo studies for medical imaging detector optimization

    NASA Astrophysics Data System (ADS)

    Fois, G. R.; Cisbani, E.; Garibaldi, F.

    2016-02-01

    This work reports on the Monte Carlo optimization studies of detection systems for Molecular Breast Imaging with radionuclides and Bremsstrahlung Imaging in nuclear medicine. Molecular Breast Imaging requires competing performances of the detectors: high efficiency and high spatial resolutions; in this direction, it has been proposed an innovative device which combines images from two different, and somehow complementary, detectors at the opposite sides of the breast. The dual detector design allows for spot compression and improves significantly the performance of the overall system if all components are well tuned, layout and processing carefully optimized; in this direction the Monte Carlo simulation represents a valuable tools. In recent years, Bremsstrahlung Imaging potentiality in internal radiotherapy (with beta-radiopharmaceuticals) has been clearly emerged; Bremsstrahlung Imaging is currently performed with existing detector generally used for single photon radioisotopes. We are evaluating the possibility to adapt an existing compact gamma camera and optimize by Monte Carlo its performance for Bremsstrahlung imaging with photons emitted by the beta- from 90 Y.

  12. Study of the surface ionization detector for gas chromatography.

    PubMed

    Li, Weiwei; Wu, Dapeng; Chen, Shiheng; Peng, Hong; Guan, Yafeng

    2011-09-23

    The structure of the surface ionization detector (SID) and the operation parameters of GC-SID were investigated to reduce peak tailing and to enhance sensitivity. The performances of the GC-SID, including its repeatability, linearity, sensitivity, selectivity, and tolerance towards water vapor, were evaluated systematically. Compared with nitrogen-phosphorus detector (NPD), the SID was able to detect fg level triethylamine, and selectively respond to alkylamines, some anilines, and some nitrogen heterocyclic compounds. Among alkylamines, the SID sensitivity to diisobutylamine was rather small. Even so, it was also still 10 times higher than that on NPD. The SID selectivity, defined as the sensitivity ratio between triethylamine and various tested non-nitrogen compounds, was higher than 10(6). It was found that the SID is highly tolerant towards water vapor, allowing direct injection of water sample. Finally, the GC-SID was applied to directly measure trace amines in headspace gases of rotted meat and trace simazine in tap water. The SID sensitivity to simazine was proven to be 5 times higher than that on flame ionization detector (FID). This study suggests that the SID is a promising GC detector. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. DETECTORS AND EXPERIMENTAL METHODS: Studies of a scintillator-bar detector for a neutron wall at an external target facility

    NASA Astrophysics Data System (ADS)

    Yu, Yu-Hong; Xu, Hua-Gen; Xu, Hu-Shan; Zhan, Wen-Long; Sun, Zhi-Yu; Guo, Zhong-Yan; Hu, Zheng-Guo; Wang, Jian-Song; Chen, Jun-Ling; Zheng, Chuan

    2009-07-01

    To achieve a better time resolution of a scintillator-bar detector for a neutron wall at the external target facility of HIRFL-CSR, we have carried out a detailed study of the photomultiplier, the wrapping material and the coupling media. The timing properties of a scintillator-bar detector have been studied in detail with cosmic rays using a high and low level signal coincidence. A time resolution of 80 ps has been achieved in the center of the scintillator-bar detector.

  14. Studying inflation with future space-based gravitational wave detectors

    SciTech Connect

    Jinno, Ryusuke; Moroi, Takeo; Takahashi, Tomo E-mail: moroi@phys.s.u-tokyo.ac.jp

    2014-12-01

    Motivated by recent progress in our understanding of the B-mode polarization of cosmic microwave background (CMB), which provides important information about the inflationary gravitational waves (IGWs), we study the possibility to acquire information about the early universe using future space-based gravitational wave (GW) detectors. We perform a detailed statistical analysis to estimate how well we can determine the reheating temperature after inflation as well as the amplitude, the tensor spectral index, and the running of the inflationary gravitational waves. We discuss how the accuracies depend on noise parameters of the detector and the minimum frequency available in the analysis. Implication of such a study on the test of inflation models is also discussed.

  15. A study of atmospheric neutrinos with the IMB detector

    NASA Technical Reports Server (NTRS)

    Losecco, J. M.; Bionta, R. M.; Blewitt, G.; Bratton, C. B.; Casper, D.; Chrysicopoulou, P.; Claus, R.; Cortez, B. G.; Errede, S.; Foster, G. W.

    1985-01-01

    A sample of 401 contained neutrino interactions collected in the 3300 metric ton fiducial mass IMB detector was used to study neutrino oscillations, geomagnetic modulation of the flux and to search for point sources. The majority of these events are attributed to neutrino interactions. For the most part, these neutrinos are believed to originate as tertiary products of cosmic ray interactions in the atmosphere. The neutrinos are a mixture of v sub e and v sub micron.

  16. Mcfast, a Parameterized Fast Monte Carlo for Detector Studies

    NASA Astrophysics Data System (ADS)

    Boehnlein, Amber S.

    McFast is a modularized and parameterized fast Monte Carlo program which is designed to generate physics analysis information for different detector configurations and subdetector designs. McFast is based on simple geometrical object definitions and includes hit generation, parameterized track generation, vertexing, a muon system, electromagnetic calorimetry, and trigger framework for physics studies. Auxiliary tools include a geometry editor, visualization, and an i/o system.

  17. Crosstalk study of near infrared InGaAs detectors

    NASA Astrophysics Data System (ADS)

    Li, Xue; Tang, Hengjing; Li, Tao; Fan, Cui; Shao, Xiumei; Li, Jianwei; Wei, Jun; Gong, Haimei

    2016-05-01

    Crosstalk characteristics of high density FPA detectors attract widespread attention in the application of electro-optical systems. Crosstalk characteristics of near-infrared (NIR) InGaAs photodiodes and focal plane arrays (FPAs) were studied in this paper. The mesa type detector was investigated by using laser beam induced current technique (LBIC) to measure the absorption outside the designed photosensitive area, and the results show that the excess absorption enlarges the crosstalk of the adjacent pixels. The structure optimization using the effective absorption layer between the pixels can effectively reduce the crosstalk to 2.5%. The major crosstalk components of the optimization photodiode come from the electronic signal caused by carrier lateral diffusion. For the planar type detectors, test structures were used to compare the crosstalk of different structures, and the guard ring structure shows good suppression of the crosstalk. Then the back-illuminated 32x32 InGaAs photodiodes with 30μm pitch were designed, and LBIC was used to measure its lateral diffusion of the effective carriers and fill factor of photosensitive area. The results indicate that the fill factor of detectors can reach up to 98% when the diffusion region is optimized, and the minimum response exists between two neighborhood pixels. Based on these crosstalk measurement results and optimizing structure designs, the linear InGaAs photodiodes were designed and thus the InGaAs FPA assembly was fabricated. The assembly shows higher electro-optical performance and good improvement on crosstalk. The assembly was applied in infrared imaging system and modulation transfer function (MTF) of FPA assembly was calculated to be above 0.50. The clear image based on FPA assembly was obtained.

  18. IXO/XMS Detector Trade-Off Study

    NASA Technical Reports Server (NTRS)

    Kilbourne, Caroline Anne; deKorte, P.; Smith, S.; Hoevers, H.; vdKuur, J.; Ezoe, Y.; Ullom, J.

    2010-01-01

    This document presents the outcome of the detector trade-off for the XMS instrument on IXO. This trade-off is part of the Cryogenic instrument Phase-A study as proposed to ESA in the Declaration of Interest SRONXMS-PL-2009-003 dated June 6, 2009. The detector consists of two components: a core array for the highest spectral resolution and an outer array to increase the field of view substantially with modest increase in the number of read-out channels. Degraded resolution of the outer array in comparison with the core array is accepted in order to make this scheme possible. The two detector components may be a single unit or separate units. These arrays comprise pixels and the components that allow them to be arrayed. Each pixel comprises a thermometer, an absorber, and the thermal links between them and to the rest of the array. These links may be interfaces or distinct components. The array infrastructure comprises the mechanical structure of the array, the arrangement of the leads, and features added to improve the integrated thermal properties of the array in the focal-plane assembly.

  19. Preliminary study of the inclusion of Water-based Liquid Scintillator in the WATCHMAN Detector

    SciTech Connect

    Sweany, Melinda; Feng, Patrick L.; Marleau, Peter

    2015-02-01

    This note summarizes an effort to characterize the effects of adding water-based liquid scintillator to the WATCHMAN detector. A detector model was built in the Geant4 Monte Carlo toolkit, and the position reconstruction of positrons within the detector was compared with and without scintillator. This study highlights the need for further modeling studies and small-scale experimental studies before inclusion into a large-scale detector, as the benefits compared to the associated costs are unclear.

  20. Feasibility studies for a wireless 60 GHz tracking detector readout

    NASA Astrophysics Data System (ADS)

    Dittmeier, S.; Schöning, A.; Soltveit, H. K.; Wiedner, D.

    2016-09-01

    The amount of data produced by highly granular silicon tracking detectors in high energy physics experiments poses a major challenge to readout systems. At high collision rates, e.g. at LHC experiments, only a small fraction of data can be read out with currently used technologies. To cope with the requirements of future or upgraded experiments new data transfer techniques are required which offer high data rates at low power and low material budget. Wireless technologies operating in the 60 GHz band or at higher frequencies offer high data rates and are thus a promising upcoming alternative to conventional data transmission via electrical cables or optical fibers. Using wireless technology, the amount of cables and connectors in detectors can be significantly reduced. Tracking detectors profit most from a reduced material budget as fewer secondary particle interactions (multiple Coulomb scattering, energy loss, etc.) improve the tracking performance in general. We present feasibility studies regarding the integration of the wireless technology at 60 GHz into a silicon tracking detector. We use spare silicon strip modules of the ATLAS experiment as test samples which are measured to be opaque in the 60 GHz range. The reduction of cross talk between links and the attenuation of reflections is studied. An estimate of the maximum achievable link density is given. It is shown that wireless links can be placed as close as 2 cm next to each other for a layer distance of 10 cm by exploiting one or several of the following measures: highly directive antennas, absorbers like graphite foam, linear polarization and frequency channeling. Combining these measures, a data rate area density of up to 11 Tb/(s·m2) seems feasible. In addition, two types of silicon sensors are tested under mm-wave irradiation in order to determine the influence of 60 GHz data transmission on the detector performance: an ATLAS silicon strip sensor module and an HV-MAPS prototype for the Mu3e

  1. Physics studies with ICARUS and a hybrid ionization and scintillation fiber detector

    SciTech Connect

    Cline, D.B.

    1992-01-01

    We discuss the physics possibilities for the ICARUS detector currently being tested at CERN. The physics potential goes from a massive proton decay detector to the study of solar neutrinos. In addition, the detection of [nu][sub [mu

  2. Investigation on gamma-ray position sensitivity at 662 keV in a spectroscopic 3' x 3' LaBr3:Ce scintillator

    NASA Astrophysics Data System (ADS)

    Giaz, A.; Camera, F.; Birocchi, F.; Blasi, N.; Boiano, C.; Brambilla, S.; Coelli, S.; Fiorini, C.; Marone, A.; Million, B.; Riboldi, S.; Wieland, O.

    2015-02-01

    The position sensitivity of a thick, cylindrical and continuous 3" x 3" (7.62 cm x 7.62 cm) LaBr3:Ce crystal was studied using a 1 mm collimated beam of 662 keV gamma rays from a 400 MBq intense 137Cs source and a spectroscopic photomultiplier (PMT) (HAMAMATSU R6233-100SEL). The PMT entrance window was covered by black absorber except for a small window 1 cm x 1 cm wide. A complete scan of the detector over a 0.5 cm step grid was performed for three positions of the 1 cm x 1 cm window. For each configuration the energy spectrum was measured and the peak centroid, the FWHM, the area and peak asymmetry of the 662 keV gamma transition were analyzed. The data show that, even in a 3" thick LaBr3:Ce crystal with diffusive surfaces the position of the full energy peak centroid depends on the source position. We verified that, on average, the position of the full energy peak centroids measured in the three 1 cm x 1 cm window configurations is sufficient for the correct identification of the collimated gamma source position.

  3. Position-sensitive change in the transition metal L-edge fine structures

    SciTech Connect

    Gulec, Ahmet; Phillips, Patrick J.; Klie, Robert F.

    2015-10-05

    Studying the structure and composition of solid-state materials on the atomic scale has become nearly routine in transmission electron microscopy with the development of novel electron optics and electron sources. In particular, with spatial resolutions better than 0.1 nm and energy resolution smaller than 100 meV, the stoichiometry, bonding, and coordination can now be examined on similar scales. Aberration-corrected scanning transmission electron microscopy and electron energy-loss spectroscopy (EELS) have played a crucial role in identifying charge ordering, valence, and as spin state transitions in transition metal perovskite oxides. In this letter, we investigate the effects of ever-decreasing electron-probe sizes on the measured near-edge fine-structure of the transition metal core-loss edge using EELS. We find that for certain transition metal perovskites, the position of the electron probe with respect to the atomic column is crucial in determining the correct valence state. Several reasons for the observed position-sensitive EELS fine-structure are discussed.

  4. Study of gas purifiers for the CMS RPC detector

    NASA Astrophysics Data System (ADS)

    Benussi, L.; Bianco, S.; Colafranceschi, S.; Fabbri, F. L.; Felli, F.; Ferrini, M.; Giardoni, M.; Greci, T.; Paolozzi, A.; Passamonti, L.; Piccolo, D.; Pierluigi, D.; Russo, A.; Saviano, G.; Buontempo, S.; Cimmino, A.; de Gruttola, M.; Fabozzi, F.; Iorio, A. O. M.; Lista, L.; Paolucci, P.; Baesso, P.; Belli, G.; Pagano, D.; Ratti, S. P.; Vicini, A.; Vitulo, P.; Viviani, C.; Guida, R.; Sharma, A.

    2012-01-01

    The CMS RPC muon detector utilizes a gas recirculation system called closed loop (CL) to cope with large gas mixture volumes and costs. A systematic study of CL gas purifiers has been carried out over 400 days between July 2008 and August 2009 at CERN in a low-radiation test area, with the use of RPC chambers with currents monitoring, and gas analysis sampling points. The study aimed to fully clarify the presence of pollutants, the chemistry of purifiers used in the CL, and the regeneration procedure. Preliminary results on contaminants release and purifier characterization are reported.

  5. Validation of the new intubation detector device: a manikin study.

    PubMed

    Umesh, Goneppanavar; Jasvinder, Kaur; Tim, Thomas Joseph

    2012-12-01

    This study was done to validate the utility of Umesh's intubation detector in detection of tracheal or oesophageal intubation in manikin using volunteers with different levels of experience in tracheal intubation (including novices). The Sim Man II, (Laerdal Medical AS, Norway) manikin was used. Two cuffed tracheal tubes of size 6.5 mm ID were used. One was passed into the trachea and the other into oesophagus. The device was connected to one of the two tubes as per randomisation table and three high quality chest compressions were performed. Each volunteer participated in the study twice. Their opinion regarding the tube position (in trachea or oesophagus or could not determine) was noted. A total of 50 volunteers participated in the study. Eleven of them had not observed intubation (novice), 29 had either only observed or had experience of <10 tracheal intubations (less experienced) and 10 had experience of >10 intubations or >1 year experience in tracheal intubation (experienced). Out of a total 100 performances, 99 were correctly identified. On one instance, a tube placed in trachea was incorrectly interpreted to be in the oesophagus by a novice. Umesh's intubation detector helps in rapid and reliable confirmation of tracheal intubation in manikin irrespective of the experience level of the assessor in tracheal intubation.

  6. CCI1 and CCI2 Detector Simulations and Figure-of-Merit Study

    SciTech Connect

    Lange, D; Manini, H; Wright, D

    2005-08-31

    We simulate the CCI1 and CCI2 detectors, using GEANT4, to study the figure of merit (FOM) for each detector. For both CCI1 and CCI2, we study how the FOM depends on strip pitch, z resolution, and lever-cut distance. For CCI2, we study how the FOM depends on the separation distance between the two silicon detectors, and the separation distance between the two germanium detectors. We also simulate future large-scale detector systems and calculate their FOM.

  7. Studies of high temperature superconductors as radiation detectors

    NASA Astrophysics Data System (ADS)

    Qiu, A.; Bhattarai, A. R.; Dahlberg, E. D.; Khan, M. Asif; Moloni, K.; van Hove, James M.

    1992-12-01

    Both DyBaCuO (DBCO) and YBaCuO (YBCO) films deposited on a variety of substrates have been investigated for their applicability as detectors of high frequency radiation. Both 10 GHz and infrared radiation (IR) were used as the high frequency radiation source. The measurements consisted of monitoring the temperature dependent resistance of superconducting films both in the presence and absence of radiation. This investigation shows that because the superconducting transition temperature is sensitive to the magnitude of the current in the film, the temperature dependence of the bolometric response is slightly tunable. In addition, effects of radiation on the current voltage characteristics below T superconducting were studied. This study found that films in this regime could also serve as radiation detectors. The substrates used included MgO, SiO, LaAlO(subscript 3), and SrTiO(subscript 3). The results obtained were independent of the substrate except for the width of the resistive transition. Disorder in the films as characterized by the resistive transition, affected the microwave more than the IR response.

  8. Small angle detectors for study diffractive processes with CMS

    NASA Astrophysics Data System (ADS)

    Albrow, M.; Bell, A. J.; Enterria, D. d.; Hall-Wilton, R.; Los, S.; Mokhov, N.; Murray, M.; Penzo, A.; Popescu, S.; Ronzhin, A.; Samoylenko, V. D.; Sobol, A.; Veres, G.

    2014-10-01

    The approach and detectors for diffractive physics based on two current projects—Forward Shower Counter (FSC) and Proton Precision Spectrometer (PPS) are presented. FSC system consists of six (3+3) Stations of scintillator counters, which surround closely the beam pipes along 59 m < |z| < 140 m from IP5 on both plus (+) and minus (-) sides. These will detect showers from very forward particles with rapidity 7.5 < |η| < 10 interacting in the beam pipe and surrounding material. FSC allow measurements of single diffraction: p+p → p+G+X (where G is rapidity gap) for lower masses and double diffraction p+p → X+G+X with a large central rapidity gap. The counters can also be used for beam real-time monitoring and will make an invaluable contribution to the understanding of the background environment and its topology. PPS is designed for study the central exclusive production pp → p+X+p, where the + signs denote the absence of hadronic activity (that is, the presence of a rapidity gap) between the outgoing protons and the decay products of the central system X. The precise measurement of the kinematical parameters of the outgoing protons enables to study the properties of the central state X. In PPS part we consider the detector for high precision timing of these protons—QUARTIC. It consists of L-shape bars with quartz or sapphire radiator. The time resolution of the QUARTIC prototypes achieved ≈ 10 ps.

  9. The Particle-Gamma Detector GODDESS

    NASA Astrophysics Data System (ADS)

    Ratkiewicz, A.; Cizewski, J. A.; Baugher, T.; Burcher, S.; Hardy, S.; Lonsdale, S.; Shand, C.; Pain, S. D.; Marsh, I.; Jones, K. L.; Peters, W. A.; Carpenter, M. P.; Seweryniak, D.; Zhu, S.; Kozub, R. L.; Afanasieva, L.; Blackmon, J. C.

    2014-09-01

    Transfer reactions in inverse kinematics provide a powerful probe of the single-particle structure of nuclei far from stability. The Californium Rare Isotope Breeder (CARIBU) at ATLAS produces exotic nuclei near possible r-process paths and makes them available for study. Gammasphere ORRUBA: Dual Detectors for Experimental Structure Studies (GODDESS) employs the large internal geometry of the high-resolution γ-ray detector Gammasphere to instrument the large-area position-sensitive particle detector ORRUBA. This coupling of Gammasphere and ORRUBA allows high-efficiency, high-resolution measurements of surrogate reactions for neutron capture, collective excitations via inelastic scattering, pickup reactions (such as (d,t)), and stripping reactions (e.g. (d,p)). Results from commissioning measurements and plans for future experiments will be presented. This work is supported in part by the U.S. Department of Energy and the National Science Foundation.

  10. A novel position-sensitive mega-size dosimeter for photoneutrons in high-energy X-ray medical accelerators.

    PubMed

    Sohrabi, Mehdi; Hakimi, Amir; Mahdavi, Seyed Rabi

    2016-06-01

    A novel position-sensitive mega-size polycarbonate (MSPC) dosimeter is introduced. It provides photoneutron (PN) dose equivalent matrix of positions in and out of a beam of a high energy X-ray medical accelerator under a single exposure. A novel position-sensitive MSPC dosimeter was developed and applied. It has an effective etched area of 50×50cm(2), as used in this study, processed in a mega-size electrochemical etching chamber to amplify PN-induced-recoil tracks to a point viewed by the unaided eyes. Using such dosimeters, PN dose equivalents, dose equivalent profiles and isodose equivalent distribution of positions in and out of beams for different X-ray doses and field sizes were determined in a Siemens ONCOR Linac. The PN dose equivalent at each position versus X-ray dose was linear up to 20Gy studied. As the field size increased, the PN dose equivalent in the beam was also increased but it remained constant at positions out of the beam up to 20cm away from the beam edge. The jaws and MLCs due to material differences and locations relative to the target produce different PN contributions. The MSPC dosimeter introduced in this study is a perfect candidate for PN dosimetry with unique characteristics such as simplicity, efficiency, dose equivalent response, large size, flexibility to be bent, resembling the patient's skin, highly position-sensitive with high spatial resolution, highly insensitive to X-rays, continuity in measurements and need to a single dosimeter to obtain PN dose equivalent matrix data under a single X-ray exposure. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  11. CsI(Na)-based radiation detector for high-resolution imaging studies using iodine 125 in small-animal research

    NASA Astrophysics Data System (ADS)

    Weisenberger, Andrew G.; Bradley, Eric; Majewski, Stan; Saha, Margaret

    1997-07-01

    We report on the development of a high resolution radiation imaging system which is capable of detecting and imaging the coincident gamma and x-ray emissions of the radioisotope iodine 125 ((superscript 125)I). Iodine 125 is commonly available as a label to molecular biology probes. Iodine 125 decays via electron capture emitting a 35 keV gamma-ray with the prompt emission of several 27 - 32 keV x rays. A coincidence condition can be set to detect the (superscript 125)I decays thus reducing background radiation contribution to the image. We are testing the use of arrays of CsI(Na) crystal scintillators coupled to position sensitive photomultiplier tubes for this application. Laboratory studies have thus far been done on mice using a prototype of our detector which is intended to be used to image gene expression in live mice to advance research in neurobiology.

  12. A new detector array for charged particle spectroscopy

    NASA Astrophysics Data System (ADS)

    Cowin, R. L.; Watson, D. L.; Chappell, S. P. G.; Clarke, N. M.; Freer, M.; Fulton, B. R.; Cunningham, R. A.; Curtis, N.; Dillon, G. K.; Lilley, J.; Jones, C. D.; Lee, P.; Rae, W. D. M.

    1999-02-01

    A compact and highly segmented detector array consisting of 44 gas-silicon-caesium iodide, position sensitive, particle identification detector telescopes and up to 10 position-sensitive, silicon strip detectors has been constructed for the study of light-ion-heavy-ion reactions including cluster break-up in the energy range 5-15MeV/nucleon. The detectors are housed in a purpose built vacuum chamber. The telescopes are placed in fixed positions, covering the forward hemisphere from 3 to 30° in the laboratory with the target placed at 535mm from the front of the telescopes or 6-52° with the target placed at 215mm. The strip detectors are placed in any of 30 fixed positions in the forward hemisphere. For 85MeV 12C ions the telescope energy resolution (gas plus silicon) is 345keV with an angular resolution of 0.03°. Using the gas-silicon section ions with Z up to 21 can be identified. For ions that pass through the silicon isotopic identification is achieved using the silicon-CsI combination. The strip detector energy resolution is 200keV, with an angular resolution of 0.1°.

  13. Charge collection studies in irradiated HV-CMOS particle detectors

    NASA Astrophysics Data System (ADS)

    Affolder, A.; Andelković, M.; Arndt, K.; Bates, R.; Blue, A.; Bortoletto, D.; Buttar, C.; Caragiulo, P.; Cindro, V.; Das, D.; Dopke, J.; Dragone, A.; Ehrler, F.; Fadeyev, V.; Galloway, Z.; Gorišek, A.; Grabas, H.; Gregor, I. M.; Grenier, P.; Grillo, A.; Hommels, L. B. A.; Huffman, T.; John, J.; Kanisauskas, K.; Kenney, C.; Kramberger, G.; Liang, Z.; Mandić, I.; Maneuski, D.; McMahon, S.; Mikuž, M.; Muenstermann, D.; Nickerson, R.; Perić, I.; Phillips, P.; Plackett, R.; Rubbo, F.; Segal, J.; Seiden, A.; Shipsey, I.; Song, W.; Stanitzki, M.; Su, D.; Tamma, C.; Turchetta, R.; Vigani, L.; Volk, J.; Wang, R.; Warren, M.; Wilson, F.; Worm, S.; Xiu, Q.; Zavrtanik, M.; Zhang, J.; Zhu, H.

    2016-04-01

    Charge collection properties of particle detectors made in HV-CMOS technology were investigated before and after irradiation with reactor neutrons. Two different sensor types were designed and processed in 180 and 350 nm technology by AMS. Edge-TCT and charge collection measurements with electrons from 90Sr source were employed. Diffusion of generated carriers from undepleted substrate contributes significantly to the charge collection before irradiation, while after irradiation the drift contribution prevails as shown by charge measurements at different shaping times. The depleted region at a given bias voltage was found to grow with irradiation in the fluence range of interest for strip detectors at the HL-LHC. This leads to large gains in the measured charge with respect to the one before irradiation. The increase of the depleted region was attributed to removal of effective acceptors. The evolution of depleted region with fluence was investigated and modeled. Initial studies show a small effect of short term annealing on charge collection.

  14. Study of gel materials as radioactive 222Rn gas detectors.

    PubMed

    Espinosa, G; Golzarri, J I; Rickards, J; Gammage, R B

    2006-01-01

    Commercial hair gel material (polyvinyl pyrolydone triethanolamine carbopol in water) and bacteriological agar (phycocolloid extracted from a group of red-purple algae, usually Gelidium sp.) have been studied as radioactive radon gas detectors. The detection method is based on the diffusion of the radioactive gas in the gel material, and the subsequent measurement of trapped products of the natural decay of radon by gamma spectrometry. From the several radon daughters with gamma radiation emission (214Pb, 214Bi, 214Po, 210Pb, 210Po), two elements, 214Pb (0.352 MeV) and 214Bi (0.609 MeV), were chosen for the analysis in this work; in order to determine the best sensitivity, corrections were made for the short half-life of the analysed isotopes. For the gamma spectrometry analysis, a hyperpure germanium solid state detector was used, associated with a PC multichannel analyser card with Maestro and Microsoft Excel software. The results show the viability of the method: a linear response in a wide radon concentration range (450-10,000 Bq m(-3)), reproducibility of data, easy handling and low cost of the gel material. This detection methodology opens new possibilities for measurements of radon and other radioactive gases.

  15. Development of a novel radiation imaging detector system for in vivo gene imaging in small animal studies

    SciTech Connect

    Weisenberger, A.G.; Majewski, S.; Bradley, E.L.

    1996-12-31

    Many studies in molecular biology deal with following the expression and regulation of a gene at different stages of an organism`s development or under different physiological conditions. Presently in situ hybridization and immunochemical assays are available to follow the gene expression at a single moment in time for one organism. One must sacrifice the organism to make a measurement, essentially taking a snap shot of the state of expression of the gene of interest. We have made progress on a new type of gene imaging technology which takes advantage of the emission properties of the radioisotope iodine 125 ({sup 125}I) as the probe and utilizes crystal scintillators and a position sensitive photomultiplier tube. Iodine 125 decays via electron capture emitting a 35 keV gamma-ray with the prompt emission of several 27-32 keV K{alpha} and K{beta} shell X-rays. Because of this a coincidence condition can be set to detect the {sup 125}I decays thus reducing background radiation contribution to the image. Mouse imaging studies of iodine uptake by the thyroid and melatonin receptor binding have been done with this detector system using low doses of {sup 125}I.

  16. Ion Studies Using Radon-222 in the EXO-200 Detector

    NASA Astrophysics Data System (ADS)

    Smith, Erica; EXO-200 Collaboration

    2015-04-01

    EXO-200 is a double beta decay experiment that uses liquid xenon enriched in xenon-136. While oscillation experiments have confirmed that neutrinos have mass, the nature of the neutrino remains elusive. The observation of neutrinoless double beta decay would confirm that the neutrino is Majorana, rather than Dirac. While studying double beta decay is the primary goal, EXO-200 can also perform many other robust analyses. Ion mobility and neutralization studies in liquid xenon detectors are particularly interesting, as the ability to extract barium ions from the detection medium and identify them would increase sensitivity to the double beta decay. We utilize the radon decay chain to perform these studies, which will be discussed in this talk. for the EXO-200 Collaboration.

  17. Experimental study of the spatially-modulated light detector

    NASA Astrophysics Data System (ADS)

    Coppée, Daniël; Pan, Wei; Stiens, Johan; Vounckx, Roger; Kuijk, Maarten

    1999-03-01

    Usually, integrated detectors in CMOS exhibit long recovery times, limiting the detector bandwidth to only a few MHz. This is due to the long absorption length and the slow diffusion speed of photo-generated carriers. Different approaches have been proposed to solve these problems hereby taxing the compatibility with standard CMOS fabrication processing. We present a novel detector for high-speed light detection in standard CMOS. To solve the problem of slow CMOS-detector recovery, the incident light is spatially modulated and the spatially modulated component of the photo-generated carrier distribution is measured. Though only a single light input signal is required, from the detector on, analog signal processing can be achieved fully differentially. Subsequently, expected good PSRR (Power supply rejection ratio) allows integration with digital circuits. Avoiding hybridization eliminates the conventional problems caused by bonding-pad capacitance, bonding-wire inductance. This reduces the associated signal degradation. In addition, the very low detector capacitance, due to the low effectively used detector area and the low area capacitance of the n-well junction, yields high voltage readout of the detector. This facilitates further amplification and conversion to digital signal levels. The detector will be applicable in arrays due to expected low cross talk. The expected fields of operation involve: serial and parallel optical communication receivers (e.g. for WDM), DVD-reading heads with integrated amplifier, etc. First measurements show 200 Mbit/s operation with a detector-responsivity of 0.05 A/W at λ=860 nm and 0.132 A/W at λ=635 nm. The detector has inherently a low capacitance, in this case only 50 fF (for an effective detector area of 70×70 μm 2).

  18. DETECTORS AND EXPERIMENTAL METHODS: Study of the RPC-Gd as thermal neutron detector

    NASA Astrophysics Data System (ADS)

    Qian, Sen; Wang, Yi-Fang; Zhang, Jia-Wen; Li, Jin; Chen, Yuan-Bo; Chen, Jin; Wang, Zhi-Gang; Ma, Lie-Hua

    2009-09-01

    The BESIII RPC with Gd coating as thermal neutron detector was designed and constructed. Three prototypes were built with different techniques of producing the gadolinium converter. The performance of the cosmic ray test, the signal and the radiation spectrum were discussed in this paper. Lastly, the efficiency of one prototype with the best performance for detecting the thermal neutron was tested as 8.7%.

  19. Position sensitivity in large spectroscopic LaBr3:Ce crystals for Doppler broadening correction

    NASA Astrophysics Data System (ADS)

    Blasi, N.; Giaz, A.; Boiano, C.; Brambilla, S.; Camera, F.; Million, B.; Riboldi, S.

    2016-12-01

    The position sensitivity of a large LaBr3:Ce crystal was investigated with the aim of correcting for the Doppler broadening in nuclear physics experiments. The crystal was cylindrical, 3 in×3 in (7.62 cm x 7.62 cm) and with diffusive surfaces as typically used in nuclear physics basic research to measure medium or high energy gamma rays (0.5 MeVPosition Sensitive Photomultipliers (PSPMT). The signals from the 256 segments of the four PSPMTs were acquired grouping them into 16 elements. An event by event analysis was performed and a positon resolution of the order of 2 cm was found. It was verified that this allows an important reduction of the Doppler broadening induced by relativistic beams in Nuclear Physics experiments.

  20. Study on the thermal imaging application of quantum cascade detectors

    NASA Astrophysics Data System (ADS)

    Zhai, Shen-Qiang; Liu, Jun-Qi; Wang, Xue-Jiao; Tan, Song; Liu, Feng-Qi; Wang, Zhan-Guo

    2014-03-01

    A 2D mechanical scanning setup was constructed, and was used to evaluate the potential of quantum cascade detector (QCD) for IR imaging. The peak responsivity of the studied QCD is 22.3 mA/W at 9.3 μm, and the Noise Equivalent Power (NEP) reaches 6.7×10-10W/Hz at temperature of 82 K. The Noise Equivalent Temperature Difference (NETD) for this imaging system is estimated to be 102.6 mK. With this experimental setup, thermal images of an operating electric soldering iron and a projection lamp at about 310 K are obtained. The image of the projection lamp demonstrates the feasibility of human body imaging with this QCD. Our research provides a proof-of-concept demonstration of thermal imaging with QCDs and displays that QCDs are potentially useful for thermal imaging applications.

  1. ;Panchito; Water Cherenkov Detector Water Studies for the LAGO Collaboration

    NASA Astrophysics Data System (ADS)

    Quishpe, R.; Audelo, M.; Calderon, M.; Carrera, E.; Cazar, D.; Guerrero, D.; Mantilla, C.; Martinez, O.; Vargas, S.; Vasquez, N.; Velasquez, C.; LAGO Collaboration

    2015-10-01

    Water Cherenkov Detectors (WCDs), which are part of the LAGO experimental array, are being built in the cities of Riobamba, Quito and Cumbaya in Ecuador. In order to increase the sensitivity and efficiency of these devices, it is necessary to ensure that the water used as radiator media absorbs as low as possible the UV light due to the incident particles and produced by Cherenkov effect. To do this, we built and used a device that allows us to measure the attenuation length directly. Water samples purified by different techniques are analyzed. Some characteristics like absorbance, refractive index, conductivity and cost are studied. We attempt to simulate the Cherenkov effect in FLUKA, we report our findings and perform a comparison with results from previous reports of LAGO sites elsewhere, and with other experiments that use WCD technology.

  2. Fabrication of Superconducting Detectors for Studying the Universe

    NASA Technical Reports Server (NTRS)

    Brown, Ari-David

    2012-01-01

    Superconducting detectors offer unparalleled means of making astronomical/cosmological observations. Fabrication of these detectors is somewhat unconventional; however, a lot of novel condensed matter physics/materials scientific discoveries and semiconductor fabrication processes can be generated in making these devices.

  3. Small angle detectors for study diffractive processes with CMS

    SciTech Connect

    Albrow, M.; Bell, A. J.; d'Enterria, D.; Hall-Wilton, R.; Los, S.; Mokhov, N.; Murray, M.; Penzo, A.; Popescu, S.; Ronzhin, A.; Samoylenko, V. D.; Sobol, A.; Veres, G.

    2014-10-22

    The approach and detectors for diffractive physics based on two current projects—Forward Shower Counter (FSC) and Proton Precision Spectrometer (PPS) are presented. FSC system consists of six (3+3) Stations of scintillator counters, which surround closely the beam pipes along 59 m < |z| < 140 m from IP5 on both plus (+) and minus (-) sides. These will detect showers from very forward particles with rapidity 7.5 < |η| < 10 interacting in the beam pipe and surrounding material. FSC allow measurements of single diffraction: p+p → p+G+X (where G is rapidity gap) for lower masses and double diffraction p+p → X+G+X with a large central rapidity gap. The counters can also be used for beam real-time monitoring and will make an invaluable contribution to the understanding of the background environment and its topology. PPS is designed for study the central exclusive production pp → p+X+p, where the + signs denote the absence of hadronic activity (that is, the presence of a rapidity gap) between the outgoing protons and the decay products of the central system X. The precise measurement of the kinematical parameters of the outgoing protons enables to study the properties of the central state X. In PPS part we consider the detector for high precision timing of these protons—QUARTIC. It consists of L-shape bars with quartz or sapphire radiator. The time resolution of the QUARTIC prototypes achieved ≈ 10 ps.

  4. Micro-pattern gas detectors for digital radiography

    NASA Astrophysics Data System (ADS)

    Altunbas, Mustafa Cem

    The gas proportional counter technology has seen vast changes in the last decade and has lead to the introduction of micro-pattern gas detectors that offer much more improved x-ray counting rate capability and better position resolution than traditional wire chambers. In this study, we investigated the Gas Electron Multiplier, a member of micro-pattern gas detector generation, as an energy sensitive, single photon-counting x-ray detector for digital radiography. We built a high pressure detector with two cascaded Gas Electron Multipliers to evaluate its performance characteristics in Neon, Argon, Krypton and Xenon mixtures. The determination of detector gain as a function of pressure and the filling gas formed the major part of this evaluation. In the second part of the study, we employed position sensitive electronics to demonstrate the imaging capability of the detector. For the first time, we acquired 2D images and examined the spatial resolution of the detector for Krypton and Xenon mixtures as a function of gas pressure using double and quadruple GEM configurations up to 7 atmospheres gas pressure. Besides the experimental studies, we constructed a theoretical model based on the Cascaded Linear Systems approach to study the imaging performance of single photon counting gas detectors. In the model, we gave the emphasis to the intrinsic properties of the gas absorber; therefore we considered the contribution of quantum efficiency, primary electron range and reabsorption of K fluorescence photons on detector MTF and DQE.

  5. Design and prototype studies of the TOTEM Roman pot detectors

    NASA Astrophysics Data System (ADS)

    Oriunno, Marco; Battistin, Michele; David, Eric; Guglielmini, Paolo; Joram, Christian; Radermacher, Ernst; Ruggiero, Gennaro; Wu, Jihao; Vacek, Vaclav; Vins, Vaclav

    2007-10-01

    The Roman pots of the TOTEM experiment at LHC will be equipped with edgeless silicon micro-strip detectors. A detector package consists of 10 detector planes cooled at -15C in vacuum. The detector resolution is 20 μm, the overall alignment precision has to be better than 30 μm. The detector planes are composed of a kapton hybrid glued on a substrate made of low expansion alloy, CE07 with 70% Si and 30% Al. An evaporative cooling system based on the fluorocarbon C3F8 with oil-free compressors has been adopted. The throttling of the fluid is done locally through capillaries. A thermo-mechanical prototype has been assembled. The results fully match the requirements and the expectations of calculations. They show a low thermal gradient on the cards and a uniform temperature distribution over the 10 planes.

  6. Hit efficiency study of CMS prototype forward pixel detectors

    SciTech Connect

    Kim, Dongwook; /Johns Hopkins U.

    2006-01-01

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

  7. The Zero-Degree Detector System for Fragmentation Studies

    NASA Technical Reports Server (NTRS)

    Adams, J. H., Jr.; Christl, M. J.; Howell, L. W.; Kuznetsov, E.

    2006-01-01

    The measurement of nuclear fragmentation cross sections requires the detection and identification of individual projectile fragments. If light and heavy fragments are recorded in 'ne same detector, it may be impossible distinguish the signal from the light fragment. To overcome this problem, we have developed the Zero-Degree Detector System. The ZDDS enables the measurement of cross sections for light fragment production by using pixelated detectors to separately measure the signals of each fragment. The system has been used to measure the fragmentation of beams as heavy as Fe at the NASA Space Radiation Laboratory at Brookhaven National Laboratory and the Heavy Ion Medical Accelerator in Chiba, Japan.

  8. Study of silicon photosensor applicability for scintillator detectors

    NASA Astrophysics Data System (ADS)

    Khilya, V. M.; Voronov, S. A.

    2016-02-01

    The aim of the present work is the creation a prototype of anticoincidence system AC for gamma-telescope GAMMA-400. The detectors of AC are developed on the basis of plastic scintillator and silicon photomultipliers. This work is focuses on research of applicability of silicon photomultipliers SiPM by company SensL, type 60000 with BC-408 plastics for the prototype of anticoincidence system detector ACtop. In frame of project the assembly for measuring of the SiPM characteristics such as the linearity, boundary of saturation, the time resolution was developed. The final stage of work was the integration of the prototype of anticoincidence detector.

  9. Hybrid gas scintillation proportional counter/phoswich detector for hard X-ray astronomy

    NASA Technical Reports Server (NTRS)

    Grindlay, Jonathan E.; Manandhar, Raj P.

    1989-01-01

    A concept is presented for a balloon-borne imaging hybrid proportional counter/phoswich detector of medium to hard X-rays. The phoswich would be optically coupled to the exit window of the proportional counter, and both detectors would use a common position-sensitive readout. It is anticipated that such a detector could combine the good energy and position resolution and excellent background rejection ability of the proportional counter for incident photon energies less than 100 keV with the extended response of the phoswich for higher energies. The phoswich could also be used to reject Compton scattering events in the proportional counter. This detector concept is studied using numerical simulations of a 400 sq cm square prototype detector. Results from this simulation indicate that current levels of proportional counter and phoswich performance are attainable at small cost in quantum efficiency, compared to a bare phoswich detector.

  10. Breast computed tomography with the PICASSO detector: A feasibility study

    NASA Astrophysics Data System (ADS)

    Rigon, Luigi; Tapete, Federica; Dreossi, Diego; Arfelli, Fulvia; Bergamaschi, Anna; Chen, Rong-Chang; Longo, Renata; Menk, Ralf-Hendrik; Schmitt, Bernd; Vallazza, Erik; Castelli, Edoardo

    2011-02-01

    The SYRMEP (Synchrotron Radiation for Medical Physics) collaboration has performed, for the first time in the world, a clinical program of mammography with synchrotron radiation. This program provided excellent results, although utilizing a commercial screen-film system as a detector. The PICASSO (Phase Imaging for Clinical Application with Silicon detector and Synchrotron radiation) project has developed a detector prototype capable of fully exploiting the peculiar characteristics of the synchrotron source, utilizing silicon microstrip sensors illuminated in the edge-on geometry and operated in single-photon counting. In this paper the potential of the PICASSO detector in breast computed tomography was evaluated by means of custom phantoms. Very encouraging results have been obtained with severe dose constrains as far as both spatial and contrast resolution are concerned. Moreover, the capability of detecting phase contrast effects was demonstrated, albeit with a higher delivered dose.

  11. Ground detectors for the study of cosmic ray showers

    NASA Astrophysics Data System (ADS)

    Salazar, H.; Villasenor, L.

    2008-06-01

    We describe the work that we have done over the last decade to design and construct instruments to measure properties of cosmic rays in Mexico. We describe the detection of decaying and crossing muons in a water Cherenkov detector and discuss an application of these results to calibrate water Cherenkov detectors. We also describe a technique to separate isolated isolated muons and electrons in water Cherenkov detector. Next we describe the design and performance of a hybrid extensive air shower detector array built on the Campus of the University of Puebla (19°N, 90°W, 800 g/cm2) to measure the energy, arrival direction and composition of primary cosmic rays with energies around 1 PeV.

  12. Experimental studies of micromegas detectors with different micro-meshes

    NASA Astrophysics Data System (ADS)

    Yang, He-Run; Hu, Bi-Tao; Zhang, Xiao-Dong; Zou, Chun-Yan

    2011-02-01

    The structure of micromegas (micro-mesh gaseous structure) detectors with different micro-meshes of stainless steel wire woven netting and Ni foil has been presented. The counting rates, energy resolution, gain, discharge probability and time resolution have been measured. Wider counter plateaus and gain for the developed detector were obtained. Excellent energy resolution of the micromegas detector, 17% (FWHM) based on Ni foil micro-mesh and 25% (FWHM) based on stainless steel wire woven netting micro-mesh, has been obtained for the 5.9 keV photon peak of the 55Fe X-ray source in an Ar/CO2(10%) gas mixture. The best time resolution at -620 V micro-mesh voltage and -870 V drift voltage is 14.8 ns for cosmic rays in an Ar/CO2 (10%) gas mixture. These results satisfy the basic demand of the micromegas detector preliminary design.

  13. High-speed detector for time-resolved diffraction studies

    PubMed Central

    Singh, Bipin; Miller, Stuart R.; Bhandari, Harish B.; Graceffa, Rita; Irving, Thomas C.; Nagarkar, Vivek V.

    2013-01-01

    There are a growing number of high brightness synchrotron sources that require high-frame-rate detectors to provide the time-scales required for performing time-resolved diffraction experiments. We report on the development of a very high frame rate CMOS X-ray detector for time-resolved muscle diffraction and time-resolved solution scattering experiments. The detector is based on a low-afterglow scintillator, provides a megapixel resolution with frame rates of up to 120,000 frames per second, an effective pixel size of 64 µm, and can be adapted for various X-ray energies. The paper describes the detector design and initial results of time-resolved diffraction experiments on a synchrotron beamline. PMID:24489595

  14. Study of counting characteristics of porous dielectric detectors of radiations

    NASA Astrophysics Data System (ADS)

    Lorikyan, M. P.

    2003-12-01

    Multiwire and microstrip porous detectors have been developed and investigated for DC operation. The multiwire porous detector consists of anode wires, an Al cathode and a gap between them filled with porous CsI. The microstrip porous detector consists of an insulating plate covered with metallic strips, micromesh cathode and a gap between them filled with porous CsI. For some time after being manufactured, these detectors' performances are non-stable and they have poor spatial resolution. However, after being kept in vacuum for a certain time, they spontaneously acquire stability and spatial resolution better than 100 μm and have detection efficiencies of 100% and 70% for heavily ionizing α-particles and 5.9 keV X-rays, respectively. The MWPDD performs stably at an intensity of heavily ionizing α-particles of 711 cts/(cm 2 s).

  15. Study of pulse shape discrimination for a neutron phoswich detector

    NASA Astrophysics Data System (ADS)

    Hartman, Jessica; Barzilov, Alexander

    2017-09-01

    A portable phoswich detector capable of differentiating between fast neutrons and thermal neutrons, and photons was developed. The detector design is based on the use of two solid-state scintillators with dissimilar scintillation time properties coupled with a single optical sensor: a 6Li loaded glass and EJ-299-33A plastic. The on-the-fly digital pulse shape discrimination and the wavelet treatment of measured waveforms were employed in the data analysis. The instrument enabled neutron spectrum evaluation.

  16. Noise and interpixel dead space studies of GaAs pixellated detectors

    NASA Astrophysics Data System (ADS)

    Abate, L.; Bertolucci, E.; Conti, M.; Mettivier, G.; Montesi, M. C.; Russo, P.

    2001-02-01

    In the framework of the development of a digital radiography/autoradiography system using solid state detectors, we studied the performance of GaAs pixellated detectors regarding noise level and detection behavior of interpixel space. The detector is a 64×64 pixel array, 200 μm thick GaAs, 150 μm contact size and 20 μm interpixel space. Studies involve I- V curves, detector behavior for long-period biasing, noise as a function of temperature, and possible detection efficiency loss due to interpixel dead spaces.

  17. Exotic geophysical phenomena observed in an environmental neutron flux study using EAS PRISMA detectors

    NASA Astrophysics Data System (ADS)

    Alekseenko, Victor; Bagrova, Anastasia; Cui, Shuwang; He, Yayun; Li, Bingbing; Ma, Xinhua; Pozdnyakov, Egor; Shchegolev, Oleg; Stenkin, Yuri; Stepanov, Vladimir

    2017-06-01

    Some exotic geophysical events are observed by a global net of electron-neutron detectors (en-detectors) developed in the framework of the PRISMA EAS project. Our en-detectors running both on the Earth's surface and underground are continuously measuring the environmental thermal neutron flux. Thermal neutrons are in equilibrium with media and are therefore sensitive to many geophysical phenomena, which are exotic for people studying ultra high-energy cosmic rays or carrying out low background experiments deep underground.

  18. Radiation tolerance studies of neutron irradiated double sided silicon microstrip detectors

    NASA Astrophysics Data System (ADS)

    Singla, M.; Larionov, P.; Balog, T.; Heuser, J.; Malygina, H.; Momot, I.; Sorokin, I.; Sturm, C.

    2016-07-01

    Radiation tolerance studies were made on double-sided silicon microstrip detectors for the Silicon Tracking System of the Compressed Baryonic Matter experiment at FAIR. The prototype detectors from two different vendors were irradiated to twice the highest expected fluence (1 ×1014 1 MeVneqcm-2) in the CBM experimental runs of several years. Test results from these prototype detectors both before and after irradiations have been discussed.

  19. Study of $WZ$ production with the DØ Detector

    SciTech Connect

    Kaadze, Ketino

    2010-01-01

    In this Dissertation I present a detailed study of p$\\bar{p}$ → WZ production using fully leptonic decays of W and Z bosons with electrons and muons in the final state. Data used for the study were collected by the DØ detector at the Fermilab p$\\bar{p}$ collider with a center-of-mass energy of √s = 1.96 TeV and correspond to 4.1 fb-1 of integrated luminosity. The most precise measurement of the WZ production cross section is obtained and found to be in a good agreement with the standard model prediction. I also present a search for new phenomena in the WZ production by investigating the coupling between W and Z bosons and by searching for new charged particles that can decay into WZ boson pair. No evidence for new physics is found, and the most stringent limits are set on the anomalous WWZ coupling parameters and masses of charged resonances. This result also sets the stringest limit on one of the possible sources of electroweak symmetry breaking, a low-scale Technicolor with a typical heavy techni-pion hypothesis.

  20. Tracking performance of GasPixel detectors in test beam studies

    NASA Astrophysics Data System (ADS)

    Boldyrev, A. S.; Hartjes, F.; Hessey, N. P.; Fransen, M.; Konovalov, S. P.; Koppert, W.; Romaniouk, A.; Shulga, E.; Smirnov, S. Yu.; Smirnov, Y.; Soldatov, E. Yu.; Tikhomirov, V. O.; Van der Graaf, H.; Vorobev, K.

    2016-01-01

    A combination of a pixel chip and a gas chamber (GasPixel detectors) opens new opportunities for particle detectors. GasPixel detectors consist of an electron drift volume, an amplification gap and an anode plane based on a semiconductor chip. This technology promises large benefits in high-energy charged-particle tracking. It allows reconstruction of a 3D image of a particle track segment in a single detector layer with high accuracy. Several prototypes of GasPixel detectors based on micromegas technology with different gas mixtures and drift gaps were studied in a test beam. A spatial resolution of 8 μm and angular accuracy of about 0.2° in a chip plane were obtained. A dedicated Monte Carlo simulation of GasPixel detectors shows good agreement with experimental data.

  1. Characterization of Resolution and Efficiency of Sodium Iodide Detectors for Reaction Studies

    NASA Astrophysics Data System (ADS)

    Waddell, Deion; Carls, Alex; Thompson, Paul; Hertz-Kintish, Daniel; G. R. A. N. D. D. A. D Collaboration

    2015-10-01

    The study of nuclear physics with radioactive ion beams requires the understanding of detectors to be used for measuring all types of radiation. Several thallium-activated sodium iodide (NaI(Tl)) detectors were characterized with gamma-ray sources to better understand their properties so they may be utilized for future experiments. A detailed understanding of the resolution and efficiency of the detectors as a function of distance from the sources to the detector, allow us to optimize the detector placement in an experimental setup. Details of the procedure and results will be presented. Work supported in part by the U.S. Department of Energy and the National Science Foundation. Gamma Ray Analysis of NaI Detectors by Daniel Alex and Deion.

  2. Study of the Quasi-Elastic Scattering in the NOvA Detector Prototype

    SciTech Connect

    Betancourt, Minerba

    2013-06-01

    NOvA is a 810 km long base-line neutrino oscillation experiment with two detectors (far 14 KTon and near detector 300 Ton) currently being installed in the NUMI o -axis neutrino beam produced at Fermilab. A 222 Ton prototype NOvA detector (NDOS) was built and operated in the neutrino beam for over a year to understand the response of the detector and its construction. The goal of this thesis is to study the muon neutrino interaction data collected in this test, specifically the identification of quasi-elastic charged-current interactions and measure the behavior of the quasi-elastic muon neutrino cross section.

  3. Optical Simulations and Studies with the PROSPECT-20 Detector

    NASA Astrophysics Data System (ADS)

    Stemen, Nathaniel; Prospect Collaboration

    2015-10-01

    The PROSPECT (Precision Reactor Oscillation and SPECTrum) experiment at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory will make a precise measurement of the reactor antineutrino spectrum from a highly-enriched uranium nuclear reactor while also probing for short-baseline oscillations as a signature of possible sterile-neutrinos. Two liquid scintillator detectors at distances of 7-10m and 16-20m from the reactor will identify inverse beta decay events initiated by reactor antineutrinos. The near detector will be divided into optically separated segments filled with lithium loaded liquid scintillator read out by photomultiplier tubes (PMTs) on either end. Light guides will be employed to direct photons from the scintillator cells to the active PMT photo-cathodes. An optical simulation was built to optimize the performance of the detectors with respect to both light collection and detector uniformity and guide the design of the scintillator cells. We present experimental data and simulation results from the PROSPECT-20 prototype detector.

  4. On accelerator-based neutron sources and neutron field characterization with low energy neutron spectrometer based on position sensitive 3He counter.

    PubMed

    Murata, I; Miyamaru, H; Kato, I; Mori, Y

    2009-07-01

    The development of new neutron sources for BNCT applications, based on particle accelerators is currently underway all over the world. Though nuclear reactors were used for a long time as the only neutron source available having the requested flux levels, the accelerator-based ones have recently been investigated on the other hand due to its easy-to-use and acceptable performances. However, when using an accelerator, various secondary particles would be emitted which forms a troublesome background. Moreover, the neutrons produced have usually an energy spectrum somewhat different from the requested one and thus should be largely moderated. An additional issue to be taken into account is the patient positioning, which should be close to the neutron source, in order to take advantage of a neutron flux level high enough to limit the BNCT treatment time within 1h. This implies that, inside a relatively narrow space, neutrons should be moderated, while unnecessary secondary particles should be shielded. Considering that a background-free neutron field from an accelerator-driven neutron source dedicated to BNCT application is generally difficult to be provided, the characterization of such a neutron field will have to be clearly assessed. In the present study, a low energy neutron spectrometer has been thus designed and is now being developed to measure the accelerator-based neutron source performance. The presently proposed spectrometer is based on a (3)He proportional counter, which is 50 cm long and 5 cm in diameter, with a gas pressure of 0.5 MPa. It is quite unique that the spectrometer is set up in parallel with the incident neutron beam and a reaction depth distribution is measured by it as a position sensitive detector. Recently, a prototype detector has been developed and the signal test is now underway. In this paper, the feature of the accelerator-based neutron sources is outlined and importance of neutron field characterization is discussed. And the developed

  5. Study of the Upsilon resonances with the CMS detector

    NASA Astrophysics Data System (ADS)

    Breto Rangel, Guillermo

    The present work focuses on detailed studies of the Upsilon(n S) resonances in lead - lead (PbPb) collisions with the CMS detector. The suppression of the Upsilon(3S) and Upsilon(2S) excited states in PbPb collisions, relative to the ground 1S state (single ratio) as well as relative to the same ratio in the proton - proton (pp) environment, known as the double ratio, is extensively studied. The study of both single and double ratios is of vital importance because it helps us quantify the suppression of the Upsilon states which in turn might be indicative of the formation of the Quark-Gluon plasma (QGP) according to several theoretical models. Based on a PbPb dataset of 150 mub-1, the measured double ratio Upsilon(2S)/Upsilon(1S) in PbPb relative to pp collisions is found to be 0.21 +/- 0.07 (stat.) +/- 0.02 (syst.). No noticeable dependencies are observed on the dimuon rapidity or transverse momentum, within the current statistical precision. No clear centrality dependence of the double ratios can be inferred from the data, while such a dependence is observed when inspecting the individual Upsilon(1S) and Upsilon(2S) nuclear modification factors, RAA. The centrality-integrated RAA values for the Upsilon(1S) and Upsilon(2S) states are 0.56 +/- 0.08 (stat.) +/- 0.07 (syst.) and 0.12 +/- 0.04 (stat.) +/- 0.02 (syst.), respectively. The 3S state is not observed prominently in the data, and upper limits on its suppression ratios are set. From the nuclear modification factor RAA for the Upsilon(1S) measurement of the initial temperature of the plasma in its most central region yielded a value of T0central=0.56 +/- 0.03 (syst.) GeV which is expected to be above the transition to QGP based on Lattice studies.

  6. Use of a pulsed magnetic field to increase the position sensitivity of a photomultiplier

    NASA Astrophysics Data System (ADS)

    Yong-Geng, Qian; Thompson, C. J.

    1987-05-01

    It is well known that photomultipliers (PMTs) are sensitive to external magnetic fields. We have used this property to vary the gain of the PMT depending on the position of the light source. Various coil configurations have been evaluated to produce local magnetic fields in the region between the photocathode and first dynode to maximize the amplitude variation in the anode signal with respect to change in the coil current. The aim was to improve the position sensitivity of a PMT used in positron emission tomography (PET). The position sensitivity was tested with an array of collimated light emitting diodes directed towards the photocathodes of a Hamamatsu R1548 PMT. The best coil position was above the photocathodes. A 60% reduction in output for light pulses from two LEDs near the coil was obtained with a current of 43 Ampere-turns while signals from two LEDs far from the coil remained the same. The rise time of the magnetic field was 2 μs.

  7. Conformable large-area position-sensitive photodetectors based on luminescence-collecting silicone waveguides

    NASA Astrophysics Data System (ADS)

    Bartu, Petr; Koeppe, Robert; Arnold, Nikita; Neulinger, Anton; Fallon, Lisa; Bauer, Siegfried

    2010-06-01

    Position sensitive detection schemes based on the lateral photoeffect rely on inorganic semiconductors. Such position sensitive devices (PSDs) are reliable and robust, but preparation with large active areas is expensive and use on curved substrates is impossible. Here we present a novel route for the fabrication of conformable PSDs which allows easy preparation on large areas, and use on curved surfaces. Our device is based on stretchable silicone waveguides with embedded fluorescent dyes, used in conjunction with small silicon photodiodes. Impinging laser light (e.g., from a laser pointer) is absorbed by the dye in the PSD and re-emitted as fluorescence light at a larger wavelength. Due to the isotropic emission from the fluorescent dye molecules, most of the re-emitted light is coupled into the planar silicone waveguide and directed to the edges of the device. Here the light signals are detected via embedded small silicon photodiodes arranged in a regular pattern. Using a mathematical algorithm derived by extensive using of models from global positioning system (GPS) systems and human activity monitoring, the position of light spots is easily calculated. Additionally, the device shows high durability against mechanical stress, when clamped in an uniaxial stretcher and mechanically loaded up to 15% strain. The ease of fabrication, conformability, and durability of the device suggests its use as interface devices and as sensor skin for future robots.

  8. A Study of Lane Differentiation Using An Array of Detectors.

    SciTech Connect

    McKigney E. A.; Gholkar, R. V.; Vega, D. A.

    2004-01-01

    The authors discuss a method for locating a radioactive source in the context of determining which lane a source is in on a roadway. This method is appropriate for use over a large range of source velocities, and could provide an advance alarm prior to a vehicle passing a portal monitor. This is a novel method which uses data from the entire array simultaneously to locate the source, rather than relying on only one or two sensors. A description of the underlying method will be given, along with results from five and six detector arrays. The five detector array was used mainly for static tests. The six detector array was used for dynamic tests, including slow movement of a source in a vehicle.

  9. High accuracy gaseous x-ray detectors

    SciTech Connect

    Smith, G.C.

    1983-11-01

    An outline is given of the design and operation of high accuracy position-sensitive x-ray detectors suitable for experiments using synchrotron radiation. They are based on the gas proportional detector, with position readout using a delay line; a detailed examination is made of factors which limit spatial resolution. Individual wire readout may be used for extremely high counting rates.

  10. Uniformity studies in large area triple-GEM based detectors

    NASA Astrophysics Data System (ADS)

    Akl, M. Abi; Bouhali, O.; Castaneda, A.; Maghrbi, Y.; Mohamed, T.

    2016-10-01

    Gas Electron Multiplier (GEM) based detectors have been used in many applications since their introduction in 1997. Large areas, e.g. exceeding 30×30 cm2, of GEM detectors are foreseen in future experiments which puts stringent requirements on the uniformity of response across the detection area. We investigate the effect of small variations of several parameters that could affect the uniformity. Parameters such as the anode pitch, the gas gap, the size and the shape of the holes are investigated. Simulation results are presented and compared to previous experimental data.

  11. Study of resolution of the PANDA GEM detector with Garfield

    NASA Astrophysics Data System (ADS)

    Melnychuk, D.; Voss, B.; Zwieglinski, B.

    2014-05-01

    The forward GEM tracker of the P̅ANDA detector at the future FAIR facility will track the particles produced in antiproton-proton annihilations and emitted in the polar angle range 5∘ -22∘. Position resolution at the level of 100 μ m and good time resolution are critical to work under luminosities up to 2×1032 c m -2 s -1. The simulations performed with Garfield program compared several detector layouts and determined the optimal granularity of readout electronics. The time resolution for two possible gas mixtures was also estimated.

  12. Acceptance Studies of an Additional Lambda Disk Detector for the PANDA Experiment

    NASA Astrophysics Data System (ADS)

    Kumar, Ajay; Roy, Ankhi; PANDA Collaboration

    2016-01-01

    The PANDA detector, which studies proton antiproton annihilations, will be installed at the future facility for antiproton and ion research in Darmstadt, Germany. PANDA has a wide physics program including the study of excited hyperon states. One very specific feature of most hyperon ground states are long decay lengths of several centimeters. The innermost tracking detector of PANDA, the Micro Vertex Detector, is not optimized for these long decay lengths. Therefore, an upgrade option is proposed adding two additional disks in the forward region called Lambda Disk Detector. For this new detector acceptance studies have been performed using the decay channel p ‾ p → Λ ‾ Λ → p ‾ pπ+π-. Simulations were carried out using the PandaRoot framework based on FairRoot.

  13. Spectroscopic performance studies of 4H-SiC detectors for fusion alpha-particle diagnostics

    NASA Astrophysics Data System (ADS)

    Raja, P. Vigneshwara; Akhtar, Jamil; Rao, C. V. S.; Vala, Sudhirsinh; Abhangi, Mitul; Murty, N. V. L. Narasimha

    2017-10-01

    The spectroscopic performances of Schottky barrier diodes (SBDs) and bulk detectors fabricated on n-type epitaxial 4H-SiC and high-purity semi-insulating (HPSI) 4H-SiC substrates are studied using 241Am alpha-particles. The spectral responses of the SBD detectors reveal a good energy resolution of 55 keV FWHM (∼1%) at -60 V, and ∼90% charge collection efficiency (CCE) at -100 V. The collected signal charge is stable with time in the SBD detectors; hence polarization effects are not noticed, indicating the good crystalline quality of the epitaxial 4H-SiC for detector applications. On the contrary, a poor energy resolution of 675 keV FWHM (12.3%) at -400 V and a maximum CCE of 28% at -500 V are obtained for the bulk detectors. Moreover, the CCE is found to decrease with time after the application of bias voltage implying the polarization phenomenon. Accordingly, the steady-state CCE of the bulk detectors at -500V is decreased to 13% from its initial value. The inferior spectral response of the bulk detectors is possibly due to the charge trapping and polarization effects. Furthermore, the neutron irradiation effects on the α-particle spectral response of the detectors are examined up to a fluence of 1011 n/cm2. To study the reliability of the SBD detectors at higher irradiation levels, the 14.1 MeV neutron irradiation induced changes in the electrical characteristics of the SBD are investigated up to a fluence of 2 × 1015n/cm2 by device simulations and the probable degradation in the detector response is analyzed. Finally, the possibility of employing 4H-SiC detectors for the fusion alpha-particle diagnostics is discussed.

  14. An electron transparent proton detector for neutron decay studies

    SciTech Connect

    Hoedl, S. A.; Young, A. R.; Ade, H.; Lozano, A.

    2006-04-15

    We have developed an ultrathin (<100 nm), very strong polyimide foil which can span more than 6x6 cm{sup 2} and is ideal for the fabrication of low energy proton detectors. We have produced a proton detector geometry in which protons incident on the foil with kinetic energies greater than about 25 keV produce, on average, more than ten secondary electrons in a conversion crystal evaporated on the back face of the foil. These secondary electrons can be ''postaccelerated'' and counted in a variety of detectors. The polyimide foils are much more durable than carbon foils previously used in similar detection geometries. LiF was chosen as the conversion crystal, which is relatively insensitive to exposure to air, improving their secondary electron yield under typical operating conditions. In addition, we describe the operation of a very simple, small scale proton accelerator and detector testing chamber capable of providing up to 10 kHz of beam with energies between 10 and 50 keV onto a biased target with a maximum ion contamination of 0.5%.

  15. Inclined Planes and Motion Detectors: A Study of Acceleration.

    ERIC Educational Resources Information Center

    Tracy, Dyanne M.

    2001-01-01

    Presents an activity in which students work in cooperative groups and roll balls down inclined planes, collect data with the help of an electronic motion detector, and represent data with a graphing calculator to explore concepts such as mass, gravity, velocity, and acceleration. (Contains 12 references.) (Author/ASK)

  16. Inclined Planes and Motion Detectors: A Study of Acceleration.

    ERIC Educational Resources Information Center

    Tracy, Dyanne M.

    2001-01-01

    Presents an activity in which students work in cooperative groups and roll balls down inclined planes, collect data with the help of an electronic motion detector, and represent data with a graphing calculator to explore concepts such as mass, gravity, velocity, and acceleration. (Contains 12 references.) (Author/ASK)

  17. The D{O} intercryostat detector: Design considerations, test beam studies and initial performance

    SciTech Connect

    Geld, T.L.

    1993-12-31

    Reported herein are the development, test beam studies and initial performance results of a novel scientific device, the Intercryostat Detector (ICD). The ICD is a subsystem in the D{O} Experiment, a major high energy physics experiment running at the Fermi National Accelerator Laboratory`s p{bar p} Tevatron collider. The D{O} detector is designed to study fundamental particle interactions at a center-of-mass energy of 1.8 TeV. The ICD plays an integral role in these studies by significantly improving the ability of D{O} to measure the energy of particle showers in a critical region of the detector. The ICD uses a layer of scintillator to sample particle showers as they pass through the detector. Its readout system is a unique design of wavelength shifting fiber bundles embedded in the scintillator, which we specifically developed for use in the ICD. During its development, we studied the ICD in a test beam. The inclusion of the Intercryostat Detector into the test beam run represents the first use of a scintillator sampling device operating in a liquid argon environment. The feasibility studies performed to develop a modified version of the ICD to operate in liquid argon are discussed. The test beam project was critical to fully exploit the ability of the ICD to improve the D{O} detector performance. The specific calibration constants for the intercryostat detectors, used to relate the detector response to the actual energy deposition in the detector, are determined from the test beam data and are presented. In addition, comparisons are made to Monte Carlo simulation data and the impact of the ICD on the D{O} detector performance is discussed.

  18. Physics validation studies for muon collider detector background simulations

    SciTech Connect

    Morris, Aaron Owen; /Northern Illinois U.

    2011-07-01

    Within the broad discipline of physics, the study of the fundamental forces of nature and the most basic constituents of the universe belongs to the field of particle physics. While frequently referred to as 'high-energy physics,' or by the acronym 'HEP,' particle physics is not driven just by the quest for ever-greater energies in particle accelerators. Rather, particle physics is seen as having three distinct areas of focus: the cosmic, intensity, and energy frontiers. These three frontiers all provide different, but complementary, views of the basic building blocks of the universe. Currently, the energy frontier is the realm of hadron colliders like the Tevatron at Fermi National Accelerator Laboratory (Fermilab) or the Large Hadron Collider (LHC) at CERN. While the LHC is expected to be adequate for explorations up to 14 TeV for the next decade, the long development lead time for modern colliders necessitates research and development efforts in the present for the next generation of colliders. This paper focuses on one such next-generation machine: a muon collider. Specifically, this paper focuses on Monte Carlo simulations of beam-induced backgrounds vis-a-vis detector region contamination. Initial validation studies of a few muon collider physics background processes using G4beamline have been undertaken and results presented. While these investigations have revealed a number of hurdles to getting G4beamline up to the level of more established simulation suites, such as MARS, the close communication between us, as users, and the G4beamline developer, Tom Roberts, has allowed for rapid implementation of user-desired features. The main example of user-desired feature implementation, as it applies to this project, is Bethe-Heitler muon production. Regarding the neutron interaction issues, we continue to study the specifics of how GEANT4 implements nuclear interactions. The GEANT4 collaboration has been contacted regarding the minor discrepancies in the neutron

  19. Precision X-ray Measurement of the Position Sensitivity of Graphene Field Effect Transistors

    SciTech Connect

    Cazalas, Edward; Sarker, Biddut K.; Moore, Michael; Childres, Isaac; Chen, Yong P.; Jovanovic, Igor

    2015-07-01

    We have been exploring the graphene field-effect transistor (GFET) as a platform for detection of ionizing radiation, whereby the detection is achieved indirectly by use of the field effect in graphene, which is induced by the generation and transport of ionized charge carriers in the underlying undoped semiconductor substrate. An important characteristic of such a detector is scalability to large areas. Previous experimental studies suggest that the effective area significantly exceeds the size of graphene for field effect-based architectures, and this is also predicted from the operational principle of these devices. We describe the results of the experimental studies of GFETs on silicon carbide (SiC) substrates by use a microbeam Xray facility, provided by the Advanced Photon Source at Argonne National Laboratory. The results confirm that the effective area of the GFET is significantly larger than that of graphene with response measured at distances as large as 1000 μm from 10-μm size graphene. A simple transport model has been developed and is used to explain the spatial dependence of the GFET response. (authors)

  20. Position-sensitive detection of ultracold neutrons with an imaging camera and its implications to spectroscopy

    NASA Astrophysics Data System (ADS)

    Wei, Wanchun; Broussard, L. J.; Hoffbauer, M. A.; Makela, M.; Morris, C. L.; Tang, Z.; Adamek, E. R.; Callahan, N. B.; Clayton, S. M.; Cude-Woods, C.; Currie, S.; Dees, E. B.; Ding, X.; Geltenbort, P.; Hickerson, K. P.; Holley, A. T.; Ito, T. M.; Leung, K. K.; Liu, C.-Y.; Morley, D. J.; Ortiz, Jose D.; Pattie, R. W.; Ramsey, J. C.; Saunders, A.; Seestrom, S. J.; Sharapov, E. I.; Sjue, S. K.; Wexler, J.; Womack, T. L.; Young, A. R.; Zeck, B. A.; Wang, Zhehui

    2016-09-01

    Position-sensitive detection of ultracold neutrons (UCNs) is demonstrated using an imaging charge-coupled device (CCD) camera. A spatial resolution less than 15 μm has been achieved, which is equivalent to a UCN energy resolution below 2 pico-electron-volts through the relation δE =m0 gδx. Here, the symbols δE, δx, m0 and g are the energy resolution, the spatial resolution, the neutron rest mass and the gravitational acceleration, respectively. A multilayer surface convertor described previously is used to capture UCNs and then emits visible light for CCD imaging. Particle identification and noise rejection are discussed through the use of light intensity profile analysis. This method allows different types of UCN spectroscopy and other applications.

  1. Position-sensitive detection of ultracold neutrons with an imaging camera and its implications to spectroscopy

    DOE PAGES

    Wei, Wanchun; Broussard, Leah J.; Hoffbauer, Mark Arles; ...

    2016-05-16

    Position-sensitive detection of ultracold neutrons (UCNs) is demonstrated using an imaging charge-coupled device (CCD) camera. A spatial resolution less than 15μm has been achieved, which is equivalent to a UCN energy resolution below 2 pico-electron-volts through the relation δE=m0gδx. Here, the symbols δE, δx, m0 and g are the energy resolution, the spatial resolution, the neutron rest mass and the gravitational acceleration, respectively. A multilayer surface convertor described previously is used to capture UCNs and then emits visible light for CCD imaging. Particle identification and noise rejection are discussed through the use of light intensity profile analysis. As a result,more » this method allows different types of UCN spectroscopy and other applications.« less

  2. Position-sensitive detection of ultracold neutrons with an imaging camera and its implications to spectroscopy

    SciTech Connect

    Wei, Wanchun; Broussard, Leah J.; Hoffbauer, Mark Arles; Makela, Mark F.; Morris, Christopher L.; Tang, Zhaowen; Adamek, Evan Robert; Callahan, Nathen Brannan; Clayton, Steven M.; Cude-Woods, Chris B.; Currie, Scott Allister; Dees, E. B.; Ding, Xinjian; Geltenbort, Peter W.; Hickerson, Kevin Peter; Holley, Adam Tarte; Ito, Takeyasu M.; Leung, Kent Kwan Ho; Liu, Chen -Yu; Morley, Deborah Jean; Ortiz, Jose D.; Pattie, Jr., Robert Wayne; Ramsey, John Clinton; Saunders, Alexander; Seestrom, Susan Joyce; Sharapov, E. I.; Sjue, Sky K.; Wexler, Jonathan William; Womack, Todd Lane; Young, Albert Raymond; Zeck, Bryan Alexander; Wang, Zhehui

    2016-05-16

    Position-sensitive detection of ultracold neutrons (UCNs) is demonstrated using an imaging charge-coupled device (CCD) camera. A spatial resolution less than 15μm has been achieved, which is equivalent to a UCN energy resolution below 2 pico-electron-volts through the relation δE=m0gδx. Here, the symbols δE, δx, m0 and g are the energy resolution, the spatial resolution, the neutron rest mass and the gravitational acceleration, respectively. A multilayer surface convertor described previously is used to capture UCNs and then emits visible light for CCD imaging. Particle identification and noise rejection are discussed through the use of light intensity profile analysis. As a result, this method allows different types of UCN spectroscopy and other applications.

  3. Continuous lateral gradients in film morphology for position sensitive detection and organic solar cell optimization

    NASA Astrophysics Data System (ADS)

    Campoy-Quiles, M.; Randon, V.; Mróz, M. M.; Jarzaguet, M.; Garriga, M.; Cabanillas-González, J.

    2013-07-01

    We present a method to fabricate binary organic donor and acceptor blends exhibiting a controlled lateral gradient in morphology. Upon combining photometry, ellipsometry and Xray maps together with photoinduced absorption measurements, we show how the gradual exposure to solvent vapor results in a varying degree of polymer crystallinity for the polythiophene/soluble fullerene system along one direction. These morphologically graded samples are characterized by a spectral photoresponse that depends on the specific location in the area of the device where the light beam impinges, a property that stands as proof-of-concept for position sensitive detection. Moreover, we demonstrate that the development of graded morphologies is an effective one-step method which allows for fast performance optimization of organic solar cells. Finally, the appropriateness of eight different solvents for morphology control via vapor annealing is evaluated in a time-effective way using the advanced method, which helps to identify boiling point and solubility as the key processing parameters.

  4. Position-sensitive detection of ultracold neutrons with an imaging camera and its implications to spectroscopy

    SciTech Connect

    Wei, Wanchun; Broussard, Leah J.; Hoffbauer, Mark Arles; Makela, Mark F.; Morris, Christopher L.; Tang, Zhaowen; Adamek, Evan Robert; Callahan, Nathen Brannan; Clayton, Steven M.; Cude-Woods, Chris B.; Currie, Scott Allister; Dees, E. B.; Ding, Xinjian; Geltenbort, Peter W.; Hickerson, Kevin Peter; Holley, Adam Tarte; Ito, Takeyasu M.; Leung, Kent Kwan Ho; Liu, Chen -Yu; Morley, Deborah Jean; Ortiz, Jose D.; Pattie, Jr., Robert Wayne; Ramsey, John Clinton; Saunders, Alexander; Seestrom, Susan Joyce; Sharapov, E. I.; Sjue, Sky K.; Wexler, Jonathan William; Womack, Todd Lane; Young, Albert Raymond; Zeck, Bryan Alexander; Wang, Zhehui

    2016-05-16

    Position-sensitive detection of ultracold neutrons (UCNs) is demonstrated using an imaging charge-coupled device (CCD) camera. A spatial resolution less than 15μm has been achieved, which is equivalent to a UCN energy resolution below 2 pico-electron-volts through the relation δE=m0gδx. Here, the symbols δE, δx, m0 and g are the energy resolution, the spatial resolution, the neutron rest mass and the gravitational acceleration, respectively. A multilayer surface convertor described previously is used to capture UCNs and then emits visible light for CCD imaging. Particle identification and noise rejection are discussed through the use of light intensity profile analysis. As a result, this method allows different types of UCN spectroscopy and other applications.

  5. Development of an optical lens based alpha-particle imaging system using position sensitive photomultiplier tube

    NASA Astrophysics Data System (ADS)

    Ando, Koki; Oka, Miki; Yamamoto, Seiichi

    2017-02-01

    We developed an optical lens based alpha-particle imaging system using position sensitive photomultiplier tube (PSPMT). The alpha-particle imaging system consists of an optical lens, an extension tube and a 1 in. square high quantum efficiency (HQE) type PSPMT. After a ZnS(Ag) is attached to subject, the scintillation image of ZnS(Ag) is focused on the photocathode of the PSPMT by the use of the optical lens. With this configuration we could image the alpha particle distribution with energy information without contacting to the subject. The spatial resolution and energy resolution were 0.8 mm FWHM and 50% FWHM at 5 mm from the optical lens, respectively. We could successfully image the alpha particle distribution in uranium ore. The developed alpha-particle imaging system will be a new tool for imaging alpha emitters with energy information without contacting the subject.

  6. Physics studies with ICARUS and a hybrid ionization and scintillation fiber detector

    SciTech Connect

    Cline, D.B.

    1992-12-31

    We discuss the physics possibilities for the ICARUS detector currently being tested at CERN. The physics potential goes from a massive proton decay detector to the study of solar neutrinos. In addition, the detection of {nu}{sub {mu}} {yields} {nu}{sub {tau}} and {nu}{sub e} {yields} {nu}{sub {tau}} will be possible with such a detector. One major topic involves the possibility of a complete determination of the MSW solar neutrino parameters with the ICARUS. The possibility of detecting WIMPS with a scintillating fiber liquid Argon (Ar) detector or fiber Xenon (Xe) detector doped with Ar is also described. Some comments on the measurement of the {sup 42}Ar level from an experiment at the Gran Sasso will be made.

  7. A theoretical study of improved front-illuminated avalanche drift detectors

    NASA Astrophysics Data System (ADS)

    Liang, K.; Yuan, J.; Li, H. R.; Yang, R.; Han, D. J.

    2013-06-01

    In this study, two avalanche drift detector (ADD) concepts were theoretically examined. One was an improved detector with an avalanche photodiode (APD) collecting and double pn-junction drift configuration, and the other was a combination of an APD collecting and metal oxide semiconductor (MOS) drift structure. The feasibility of the devices was theoretically investigated by the ISE-TCAD program. ADD can be operated in either Geiger mode or linear mode. In the former case, the detector was found to be appropriate for a single photon avalanche detector with a large collection area. In the latter case, the detector was observed to be well suited to be coupled to a scintillator for gamma-ray detection. The improved ADDs are considered to have good performances in the short wavelength optical detection and in matching common scintillation crystals with more flexibility.

  8. The KACST muon detector and its application to cosmic-ray variations studies

    NASA Astrophysics Data System (ADS)

    Maghrabi, A. H.; Al Harbi, H.; Al-Mostafa, Z. A.; Kordi, M. N.; Al-Shehri, S. M.

    2012-09-01

    A single channel cosmic ray muon detector was constructed and installed in Riyadh, central Saudi Arabia, for studying the variations in the cosmic ray (CR) muon flux. The detector has been in operation since July 2002. The recorded data correspond to muons that primarily have energies between 10 and 20 GeV. The detector will be used to continuously measure the intensity of the muon components of the cosmic rays, exploring its variations and possible correlations with environment parameters. The technical aspects of this detector will be presented. Some results obtained by the detector so far will be given. These include the modulation of the CR flux on different time scales (diurnal, 27-day, and long-term variations). Additionally, the effect of a severe dust storm on the muon count rate was investigated.

  9. A simulation study on angular and micro pattern effects in GEM detectors.

    PubMed

    Kim, H G; Jamil, M; Rhee, J T; Ahmad, Farzana; Jeon, Y J

    2016-04-01

    A useful approach for the enhancement of thermal neutrons detection has been reported here. This technique, based on the angular and micro pattern effects, has been developed and applied to the boron-coated ((10)B) Gas Electron multiplier (GEM) detector. In the angular effect case, as a general rule, the detector device is turned at an angle which improves the device response per unit area of the detector. While for the latter case, a regular pattern in the form of micrometer deep grooves is fabricated onto the converter coating, consequently it enhances the capture probability of the detector. For the current study, both of these techniques using a (10)B-coated GEM detector have been simulated for low energy neutrons. For the evaluation of detector response thermal neutrons in the energy ranges from 25meV to 100meV were transported onto the detector surface. For this work, FLUKA MC code has been utilized. The output in both cases has been estimated as a function of incident thermal neutron energies. By employing both techniques, the angle and the micro pattern dependent efficiencies for (10)B-coated GEM detectors are presented, which indicate an improved efficiency response of the device. We anticipate that by using these modifications can lead a further forward step in the development and improvement of thermal neutron detection technology. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Simulation study of PET detector limitations using continuous crystals

    NASA Astrophysics Data System (ADS)

    Cabello, Jorge; Etxebeste, Ane; Llosá, Gabriela; Ziegler, Sibylle I.

    2015-05-01

    Continuous crystals can potentially obtain better intrinsic detector spatial resolution compared to pixelated crystals, additionally providing depth of interaction (DoI) information from the light distribution. To achieve high performance sophisticated interaction position estimation algorithms are required. There are a number of algorithms in the literature applied to different crystal dimensions and different photodetectors. However, the different crystal properties and photodetector array geometries have an impact on the algorithm performance. In this work we analysed, through Monte Carlo simulations, different combinations of realistic crystals and photodetector parameters to better understand their influence on the interaction position estimation accuracy, with special emphasis on the DoI. We used an interaction position estimation based on an analytical model for the present work. Different photodetector granulation schemes were investigated. The impact of the number of crystal faces readout by photodetectors was studied by simulating scenarios with one and two photodetectors. In addition, crystals with different levels of reflection and aspect ratios (AR) were analysed. Results showed that the impact of photodetector granularity is mainly shown near the edges and specially in the corners of the crystal. The resulting intrinsic spatial resolution near the centre with a 12 × 12 × 10 mm3 LYSO crystal was 0.7-0.9 mm, while the average spatial resolution calculated on the entire crystal was 0.77 ± 0.18 mm for all the simulated geometries with one and two photodetectors. Having front and back photodetectors reduced the DoI bias (Euclidean distance between estimated DoI and real DoI) and improved the transversal resolution near the corners. In scenarios with one photodetector, small AR resulted in DoI inaccuracies for absorbed events at the entrance of the crystal. These inaccuracies were slightly reduced either by increasing the AR or reducing the amount of

  11. Simulation study of PET detector limitations using continuous crystals.

    PubMed

    Cabello, Jorge; Etxebeste, Ane; Llosá, Gabriela; Ziegler, Sibylle I

    2015-05-07

    Continuous crystals can potentially obtain better intrinsic detector spatial resolution compared to pixelated crystals, additionally providing depth of interaction (DoI) information from the light distribution. To achieve high performance sophisticated interaction position estimation algorithms are required. There are a number of algorithms in the literature applied to different crystal dimensions and different photodetectors. However, the different crystal properties and photodetector array geometries have an impact on the algorithm performance. In this work we analysed, through Monte Carlo simulations, different combinations of realistic crystals and photodetector parameters to better understand their influence on the interaction position estimation accuracy, with special emphasis on the DoI. We used an interaction position estimation based on an analytical model for the present work. Different photodetector granulation schemes were investigated. The impact of the number of crystal faces readout by photodetectors was studied by simulating scenarios with one and two photodetectors. In addition, crystals with different levels of reflection and aspect ratios (AR) were analysed. Results showed that the impact of photodetector granularity is mainly shown near the edges and specially in the corners of the crystal. The resulting intrinsic spatial resolution near the centre with a 12 × 12 × 10 mm(3) LYSO crystal was 0.7-0.9 mm, while the average spatial resolution calculated on the entire crystal was 0.77 ± 0.18 mm for all the simulated geometries with one and two photodetectors. Having front and back photodetectors reduced the DoI bias (Euclidean distance between estimated DoI and real DoI) and improved the transversal resolution near the corners. In scenarios with one photodetector, small AR resulted in DoI inaccuracies for absorbed events at the entrance of the crystal. These inaccuracies were slightly reduced either by increasing the AR or reducing the amount

  12. Muon background studies for shallow depth Double - Chooz near detector

    SciTech Connect

    Gómez, H.

    2015-08-17

    Muon events are one of the main concerns regarding background in neutrino experiments. The placement of experimental set-ups in deep underground facilities reduce considerably their impact on the research of the expected signals. But in the cases where the detector is installed on surface or at shallow depth, muon flux remains high, being necessary their precise identification for further rejection. Total flux, mean energy or angular distributions are some of the parameters that can help to characterize the muons. Empirically, the muon rate can be measured in an experiment by a number of methods. Nevertheless, the capability to determine the muons angular distribution strongly depends on the detector features, while the measurement of the muon energy is quite difficult. Also considering that on-site measurements can not be extrapolated to other sites due to the difference on the overburden and its profile, it is necessary to find an adequate solution to perform the muon characterization. The method described in this work to obtain the main features of the muons reaching the experimental set-up, is based on the muon transport simulation by the MUSIC software, combined with a dedicated sampling algorithm for shallow depth installations based on a modified Gaisser parametrization. This method provides all the required information about the muons for any shallow depth installation if the corresponding overburden profile is implemented. In this work, the method has been applied for the recently commissioned Double - Chooz near detector, which will allow the cross-check between the simulation and the experimental data, as it has been done for the far detector.

  13. Muon background studies for shallow depth Double - Chooz near detector

    NASA Astrophysics Data System (ADS)

    Gómez, H.

    2015-08-01

    Muon events are one of the main concerns regarding background in neutrino experiments. The placement of experimental set-ups in deep underground facilities reduce considerably their impact on the research of the expected signals. But in the cases where the detector is installed on surface or at shallow depth, muon flux remains high, being necessary their precise identification for further rejection. Total flux, mean energy or angular distributions are some of the parameters that can help to characterize the muons. Empirically, the muon rate can be measured in an experiment by a number of methods. Nevertheless, the capability to determine the muons angular distribution strongly depends on the detector features, while the measurement of the muon energy is quite difficult. Also considering that on-site measurements can not be extrapolated to other sites due to the difference on the overburden and its profile, it is necessary to find an adequate solution to perform the muon characterization. The method described in this work to obtain the main features of the muons reaching the experimental set-up, is based on the muon transport simulation by the MUSIC software, combined with a dedicated sampling algorithm for shallow depth installations based on a modified Gaisser parametrization. This method provides all the required information about the muons for any shallow depth installation if the corresponding overburden profile is implemented. In this work, the method has been applied for the recently commissioned Double - Chooz near detector, which will allow the cross-check between the simulation and the experimental data, as it has been done for the far detector.

  14. Development of a cold-neutron imaging detector based on thick gaseous electron multiplier.

    PubMed

    Cortesi, M; Zboray, R; Kaestner, A; Prasser, H-M

    2013-02-01

    We present the results of our recent studies on a cold-neutron imaging detector prototype based on THick Gaseous Electron Multiplier (THGEM). The detector consists of a thin Boron layer, for neutron-to-charged particle conversion, coupled to two THGEM electrodes in cascade for charge amplification and a position-sensitive charge-readout anode. The detector operates in Ne∕(5%)CF4, at atmospheric pressure, in a stable condition at a gain of around 10(4). Due to the geometrical structure of the detector elements (THGEM geometry and charge read-out anode), the image of detector active area shows a large inhomogeneity, corrected using a dedicated flat-filed correction algorithm. The prototype provides a detection efficiency of 5% and an effective spatial resolution of the order of 1.3 mm.

  15. Simulation Study of RICH Detector for Particle Identification in Forward Region at Electron-Ion Collider

    NASA Astrophysics Data System (ADS)

    Wong, Cheuk-Ping

    2015-04-01

    eRD11 R&D program is focusing on the technology exploration for hadron particle identification in the forward region of Electron-Ion Collider (EIC) for studying quark and gluon distributions inside the nucleon. A modular Ring Imaging Cherenkov (RICH) detector has been extensively studied in Geant4-based simulation. The detector consists of a block of aerogel, Fresnel lens, four side mirrors and a photosensor plane. The simulated performance of this detector will be presented in this talk. For the eRD11 Collaboration.

  16. Preliminary study of a metal/a-Se-based portal detector.

    PubMed

    Falco, T; Wang, H; Fallone, B G

    1998-06-01

    A feasibility study has been performed on metal/amorphous selenium detectors for megavoltage portal imaging. The metal plates of the detectors were positioned facing the incident 6 MV and Co-60 photon spectra. The detectors consist of various thicknesses (0.15 mm, 0.30 mm, and 0.50 mm) of amorphous selenium (a-Se) deposited on metal plates of varying thicknesses: aluminum (2.0 mm), copper (1.0 mm and 1.5 mm), stainless steel (0.9 mm), or glass (1.1 mm). The detectors were charged prior to irradiation by corona methods, and the portal images were subsequently digitized after irradiation with a noncontact electrostatic probe. The sensitivity of the detectors to dose, electric field across the a-Se layer, metal plate type and a-Se thickness, was studied. The electrostatic voltage remaining on the a-Se layer was found, both theoretically and experimentally, to exhibit a cubic relationship with respect to dose. An increase in electric field increases the sensitivity (gradient of the a-Se surface voltage vs dose curve) and dynamic range of the resultant image. An increase in a-Se thickness, however, although also increasing the sensitivity, decreases the dynamic range. The metal plate types and thicknesses within the range studied do not have a significant effect on detector sensitivity. Image quality and contrast resolution of the detector were evaluated with a contrast-detail phantom and compared to commercially available film based and electronic portal imaging devices. Image quality of the metal/a-Se detector as a function of dose was studied by discharging the a-Se to various fractions of its initial charge, and as expected, increases with dose due to a decrease in quantum noise. Contrast-detail images obtained by metal/a-Se detectors are superior to those obtained at higher dose levels by other commercial systems.

  17. The Silicon Pixel Detector for ALICE Experiment

    SciTech Connect

    Fabris, D.; Bombonati, C.; Dima, R.; Lunardon, M.; Moretto, S.; Pepato, A.; Bohus, L. Sajo; Scarlassara, F.; Segato, G.; Shen, D.; Turrisi, R.; Viesti, G.; Anelli, G.; Boccardi, A.; Burns, M.; Campbell, M.; Ceresa, S.; Conrad, J.; Kluge, A.; Kral, M.

    2007-10-26

    The Inner Tracking System (ITS) of the ALICE experiment is made of position sensitive detectors which have to operate in a region where the track density may be as high as 50 tracks/cm{sup 2}. To handle such densities detectors with high precision and granularity are mandatory. The Silicon Pixel Detector (SPD), the innermost part of the ITS, has been designed to provide tracking information close to primary interaction point. The assembly of the entire SPD has been completed.

  18. A study of nuclear recoil backgrounds in dark matter detectors

    NASA Astrophysics Data System (ADS)

    Westerdale, Shawn S.

    Despite the great success of the Standard Model of particle physics, a preponderance of astrophysical evidence suggests that it cannot explain most of the matter in the universe. This so-called dark matter has eluded direct detection, though many theoretical extensions to the Standard Model predict the existence of particles with a mass on the 1-1000 GeV scale that interact only via the weak nuclear force. Particles in this class are referred to as Weakly Interacting Massive Particles (WIMPs), and their high masses and low scattering cross sections make them viable dark matter candidates. The rarity of WIMP-nucleus interactions makes them challenging to detect: any background can mask the signal they produce. Background rejection is therefore a major problem in dark matter detection. Many experiments greatly reduce their backgrounds by employing techniques to reject electron recoils. However, nuclear recoil backgrounds, which produce signals similar to what we expect from WIMPs, remain problematic. There are two primary sources of such backgrounds: surface backgrounds and neutron recoils. Surface backgrounds result from radioactivity on the inner surfaces of the detector sending recoiling nuclei into the detector. These backgrounds can be removed with fiducial cuts, at some cost to the experiment's exposure. In this dissertation we briefly discuss a novel technique for rejecting these events based on signals they make in the wavelength shifter coating on the inner surfaces of some detectors. Neutron recoils result from neutrons scattering off of nuclei in the detector. These backgrounds may produce a signal identical to what we expect from WIMPs and are extensively discussed here. We additionally present a new tool for calculating (alpha, n) yields in various materials. We introduce the concept of a neutron veto system designed to shield against, measure, and provide an anti-coincidence veto signal for background neutrons. We discuss the research and development

  19. A Study of Nuclear Recoil Backgrounds in Dark Matter Detectors

    SciTech Connect

    Westerdale, Shawn S.

    2016-01-01

    Despite the great success of the Standard Model of particle physics, a preponderance of astrophysical evidence suggests that it cannot explain most of the matter in the universe. This so-called dark matter has eluded direct detection, though many theoretical extensions to the Standard Model predict the existence of particles with a mass on the $1-1000$ GeV scale that interact only via the weak nuclear force. Particles in this class are referred to as Weakly Interacting Massive Particles (WIMPs), and their high masses and low scattering cross sections make them viable dark matter candidates. The rarity of WIMP-nucleus interactions makes them challenging to detect: any background can mask the signal they produce. Background rejection is therefore a major problem in dark matter detection. Many experiments greatly reduce their backgrounds by employing techniques to reject electron recoils. However, nuclear recoil backgrounds, which produce signals similar to what we expect from WIMPs, remain problematic. There are two primary sources of such backgrounds: surface backgrounds and neutron recoils. Surface backgrounds result from radioactivity on the inner surfaces of the detector sending recoiling nuclei into the detector. These backgrounds can be removed with fiducial cuts, at some cost to the experiment's exposure. In this dissertation we briefly discuss a novel technique for rejecting these events based on signals they make in the wavelength shifter coating on the inner surfaces of some detectors. Neutron recoils result from neutrons scattering from nuclei in the detector. These backgrounds may produce a signal identical to what we expect from WIMPs and are extensively discussed here. We additionally present a new tool for calculating ($\\alpha$, n)yields in various materials. We introduce the concept of a neutron veto system designed to shield against, measure, and provide an anti-coincidence veto signal for background neutrons. We discuss the research and development

  20. Large Format CMOS-based Detectors for Diffraction Studies

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  1. Some results of test beam studies of Transition Radiation Detector prototypes at CERN

    NASA Astrophysics Data System (ADS)

    Tikhomirov, V. O.; Brooks, T.; Joos, M.; Rembser, C.; Celebi, E.; Gurbuz, S.; Cetin, S. A.; Konovalov, S. P.; Zhukov, K.; Fillipov, K. A.; Romaniouk, A.; Smirnov, S. Yu; Teterin, P. E.; Vorobev, K. A.; Boldyrev, A. S.; Maevsky, A.; Derendarz, D.

    2017-01-01

    Operating conditions and challenging demands of present and future accelerator experiments result in new requirements on detector systems. There are many ongoing activities aimed to develop new technologies and to improve the properties of detectors based on existing technologies. Our work is dedicated to development of Transition Radiation Detectors (TRD) suitable for different applications. In this paper results obtained in beam tests at SPS accelerator at CERN with the TRD prototype based on straw technology are presented. TRD performance was studied as a function of thickness of the transition radiation radiator and working gas mixture pressure.

  2. Building and commissioning of a setup to study ageing phenomena in gaseous detectors

    NASA Astrophysics Data System (ADS)

    Abuhoza, A.; Schmidt, H. R.; Biswas, S.; Frankenfeld, U.; Hehner, J.; Schmidt, C. J.

    2016-07-01

    In high-rate heavy-ion experiments, gaseous detectors encounter big challenges in terms of degradation of their performance due to a phenomenon called ageing. A setup for high precision ageing studies has been constructed and commissioned at the GSI detector laboratory. The setup as well as the gas system have been carefully optimized to reach a high sensitivity for ageing effects. Two different materials have been examined for their influence on gaseous detectors: RTV-3145 and Gerband 705. The details of the construction of the ageing test setup and the test results will be presented.

  3. Development of a single ion detector for radiation track structure studies

    NASA Astrophysics Data System (ADS)

    Vasi, F.; Casiraghi, M.; Bashkirov, V.; Giesen, U.; Schulte, R. W.

    2016-09-01

    The track structure of ionizing radiation predominantly determines the biological effects after irradiation. A new detector to register 3D track structure segments in low pressure gas was proposed in a previous work. The device combines the operational principle of thick gas electron multipliers (THGEM), working in reverse polarity, and resistive plate chambers. In this work, the detector was further developed. Optimization of THGEM thickness, hole pitch and cathode resistivity were studied. A new detector prototype was built and tested with a microbeam providing different radiation qualities. The detector rate capability and ion collection efficiency were also investigated. Results show that the detector efficiency increases with increasing THGEM thickness and decreasing cathode resistivity. Preliminary results show that the ion collection efficiency is low and that the detector performance is limited by a long dead time. The detector is able to register single ions with a low dark rate. However, further development is needed in order to obtain the efficiency necessary to reconstruct 3D track structure.

  4. Rad-hard electronics study for SSC detectors

    SciTech Connect

    Ekenberg, T.; Dawson, J.; Stevens, A.; Haberichter, W.

    1991-01-01

    The radiation environment in a SSC detector operating at a luminosity of 10{sup 33} cm{sup {minus}2}s{sup {minus}1} will put stringent requirements on radiation hardness of the electronics. Over the expected 10 year life-time of a large detector, ionizing radiation doses of up to 20 MRad and neutron fluences of 10{sup 16} neutrons/cm{sup 2} are projected. At a luminosity of 10{sup 34} cm{sup {minus}2}s{sup {minus}1} even higher total doses are expected. the effect of this environment have been simulated by exposing CMOS/bulk and CMOS/SOS devices from monolithic processes to neutrons and ionizing radiation. leakage currents, noise variations, and DC characteristics have been measured before and after exposure in order to evaluate the effects of the irradiations. As expected the device characteristics remained virtually unchanged by neutron irradiation, while ionizing radiation caused moderate degradation of performance. 5 refs., 6 figs.

  5. DETECTORS AND EXPERIMENTAL METHODS: Study on the TU gas for the GEM-TPC detector

    NASA Astrophysics Data System (ADS)

    Qi, Hui-Rong; Li, Yu-Lan; Li, Jin; Gao, Yuan-Ning; Li, Yuan-Jing

    2009-04-01

    In this paper several different working gas mixtures for GEM-TPC were evaluated based on a Garfield simulation. Among them, Ar:CH4:CF4 = 90:7:3 (named herein TU gas) was selected for a detailed study because of its better performance. Some performances of drift velocity, transverse diffusion, spatial resolution and the effective number of electrons in various electric fields were obtained. The performance of a GEM-TPC prototype working in the TU gas was studied and compared with that in Ar:CH4 = 90:10 (P10 gas).

  6. Position-sensitive proportional counter with low-resistance metal-wire anode

    DOEpatents

    Kopp, Manfred K.

    1980-01-01

    A position-sensitive proportional counter circuit is provided which allows the use of a conventional (low-resistance, metal-wire anode) proportional counter for spatial resolution of an ionizing event along the anode of the counter. A pair of specially designed active-capacitance preamplifiers are used to terminate the anode ends wherein the anode is treated as an RC line. The preamplifiers act as stabilized active capacitance loads and each is composed of a series-feedback, low-noise amplifier, a unity-gain, shunt-feedback amplifier whose output is connected through a feedback capacitor to the series-feedback amplifier input. The stabilized capacitance loading of the anode allows distributed RC-line position encoding and subsequent time difference decoding by sensing the difference in rise times of pulses at the anode ends where the difference is primarily in response to the distributed capacitance along the anode. This allows the use of lower resistance wire anodes for spatial radiation detection which simplifies the counter construction and handling of the anodes, and stabilizes the anode resistivity at high count rates (>10.sup.6 counts/sec).

  7. ROSAT Position Sensitive Proportional Counter spectra of six Seyfert 1 galaxies

    NASA Technical Reports Server (NTRS)

    Turner, T. J.; George, I. M.; Mushotzky, R. F.

    1993-01-01

    We present the results from ROSAT Position Sensitive Proportional Counter observations of six Seyfert 1 galaxies in the soft (0.1-2.0 keV) X-ray band. The sources (Mrk 335, ESO 198-G24, ESO 141-G55, Mrk 509, NGC 7469, and MCG-2-58-22) were chosen to have low absorbing column densities along the line of sight. As expected, it is found that all the sources possess significantly steeper spectra below about 1 keV than observed at higher X-ray energies. Assuming a simple absorbed power-law spectral model, the mean (photon) spectral index for the sample is Gamma = 2.38 +/- 0.25, compared to the canonical 1.7 typically observed in the 2-10 keV band. Furthermore, we find strong evidence for soft X-ray spectral features in half the sources. In NGC 7469 and ESO 198-G24, we find that the addition of a narrow emission line or an absorption edge to the underlying continuum is a significant improvement to the parameterization of the spectra. Mrk 335 also shows evidence for spectral complexity, but from these data it is not possible to unambiguously distinguish between an absorption edge and a steepening of the spectrum at low energies. We examine these results in the light of the accuracy of the PSPC spectral calibration.

  8. Localized Surface Plasmon Induced Position-Sensitive Photodetection in Silicon-Nanowire-Modified Ag/Si.

    PubMed

    Mei, Chunlian; Liu, Shuai; Huang, Xu; Gan, Zhikai; Zhou, Peiqi; Wang, Hui

    2017-09-22

    Surface plasmon-based approaches are widely applied to improve the efficiency of photoelectric devices such as photosensors and photocells. In order to promote the light absorption and electron-hole pair generation in devices, metallodielectric nanostructures are used to boost the growth of surface plasmons. Here, silicon nanowires (SiNWs) are used to modify a metal-semiconductor structure; thus, Ag/SiNWs/Si is manufactured. In this system, a large increased lateral photovoltaic effect (LPE) is detected with a maximum positional sensitivity of 65.35 mV mm(-1) , which is ≈53-fold and 1000-fold compared to the conventional Ag/Si (1.24 mV mm(-1) ) and SiNWs/Si (0.06 mV mm(-1) ), respectively. It is demonstrated that localized surface plasmons (LSPs) contribute a lot to the increment of LPE. Furthermore, through the surface-enhanced Raman scattering spectra of rhodamine-6G and finite-difference time-domain simulation, it is illustrated that silver-coated SiNWs support strong LSPs. The results propose an enhancement mechanism based on LSPs to facilitate the photoelectric conversion in LPE and offer an effective way to improve the sensitivity of photodetectors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Error detection capability of a novel transmission detector: a validation study for online VMAT monitoring

    NASA Astrophysics Data System (ADS)

    Pasler, Marlies; Michel, Kilian; Marrazzo, Livia; Obenland, Michael; Pallotta, Stefania; Björnsgard, Mari; Lutterbach, Johannes

    2017-09-01

    The purpose of this study was to characterize a new single large-area ionization chamber, the integral quality monitor system (iRT, Germany), for online and real-time beam monitoring. Signal stability, monitor unit (MU) linearity and dose rate dependence were investigated for static and arc deliveries and compared to independent ionization chamber measurements. The dose verification capability of the transmission detector system was evaluated by comparing calculated and measured detector signals for 15 volumetric modulated arc therapy plans. The error detection sensitivity was tested by introducing MLC position and linac output errors. Deviations in dose distributions between the original and error-induced plans were compared in terms of detector signal deviation, dose-volume histogram (DVH) metrics and 2D γ-evaluation (2%/2 mm and 3%/3 mm). The detector signal is linearly dependent on linac output and shows negligible (<0.4%) dose rate dependence up to 460 MU min‑1. Signal stability is within 1% for cumulative detector output; substantial variations were observed for the segment-by-segment signal. Calculated versus measured cumulative signal deviations ranged from  ‑0.16%–2.25%. DVH, mean 2D γ-value and detector signal evaluations showed increasing deviations with regard to the respective reference with growing MLC and dose output errors; good correlation between DVH metrics and detector signal deviation was found (e.g. PTV D mean: R 2  =  0.97). Positional MLC errors of 1 mm and errors in linac output of 2% were identified with the transmission detector system. The extensive tests performed in this investigation show that the new transmission detector provides a stable and sensitive cumulative signal output and is suitable for beam monitoring during patient treatment.

  10. Fabrication process development for high-purity germanium radiation detectors with amorphous semiconductor contacts

    NASA Astrophysics Data System (ADS)

    Looker, Quinn

    High-purity germanium (HPGe) radiation detectors are well established as a valuable tool in nuclear science, astrophysics, and nuclear security applications. HPGe detectors excel in gamma-ray spectroscopy, offering excellent energy resolution with large detector sizes for high radiation detection efficiency. Although a robust fabrication process has been developed, improvement is needed, especially in developing electrical contact and surface passivation technology for position-sensitive detectors. A systematic study is needed to understand how the detector fabrication process impacts detector performance and reliability. In order to provide position sensitivity, the electrical contacts are segmented to form multiple electrodes. This segmentation creates new challenges in the fabrication process and warrants consideration of additional detector effects related to the segmentation. A key area of development is the creation of the electrical contacts in a way that enables reliable operation, provides low electronic noise, and allows fine segmentation of electrodes, giving position sensitivity for radiation interactions in the detector. Amorphous semiconductor contacts have great potential to facilitate new HPGe detector designs by providing a thin, high-resistivity surface coating that is the basis for electrical contacts that block both electrons and holes and can easily be finely segmented. Additionally, amorphous semiconductor coatings form a suitable passivation layer to protect the HPGe crystal surface from contamination. This versatility allows a simple fabrication process for fully passivated, finely segmented detectors. However, the fabrication process for detectors with amorphous semiconductors is not as highly developed as for conventional technologies. The amorphous semiconductor layer properties can vary widely based on how they are created and these can translate into varying performance of HPGe detectors with these contacts. Some key challenges include

  11. The MOON-1 detector construction and the study of backgrounds from radioactive isotopes

    NASA Astrophysics Data System (ADS)

    Ogama, T.; Nakamura, H.; Ejiri, H.; Fushimi, K.; Ichihara, K.; Matsuoka, K.; Nomachi, M.; Hazama, R.; Umehara, S.; Yoshida, S.; Sakiuchi, T.; Hai, V. H.; Sugaya, Y.; Moon Collaboration

    2006-05-01

    MOON is a multilayer system of plastic scintillators and 100Mo films for 100Mo 0νββ decays. A prototype detector MOON-1 was built with 6 layers of plastic scintillators and 142g of 100Mo films for background (BG), energy and position resolution studies of the MOON detector. No serious BG from natural radioactive isotopes (RI) for 0νββ detection was found.

  12. Study of the Influence of Construction Materials on the Ageing Properties of High Rate Gas Detectors

    NASA Astrophysics Data System (ADS)

    Abuhoza, Alhussain; Biswas, S.; Frankenfeld, U.; Hehner, J.; Schmidt, C. J.; Schmidt, H. R.

    An infrastructure has been set up at the GSI detector laboratory to study the influence of construction materials on the ageing properties of gas filled detectors such as multi wire proportional chambers (MWPC), gas electron multipliers (GEM) etc. As a first step an ageing test of silicone-based glue (RTV-3145)(Dow Corning) has been performed. In this article details of the experimental set-up and the first result on (RTV3145) will be presented.

  13. [CW bio-radar vital sign detector and experiment study].

    PubMed

    Hu, Wei; Wang, Yunfeng; Zhao, Zhangyan; Zhang, Haiying

    2014-03-01

    Non-contact vital sign detection technique provides an effective usage in health monitoring applications. A vital sign detector was designed based on microwave bio-radar technique. Using Doppler principle, continuous wave bioradar was designed for tiny body movement detection, short-time Fourier transform and interpolation algorithm were adopted for heart and respiration rate extraction, embedded system was used for system integration, real-time signal processing software was designed on it. Experiments were done by using simulation device and human body for research and performance evaluation. The result shows that the proposed prototype can be used for single target vital signs detection at the distance of 90 cm, and the heart rate result shows a 96% recognition rate.

  14. Jet azimuthal decorrelation studies with the D-zero detector

    SciTech Connect

    Feher, S.

    1996-10-01

    Experimental results on the measurement of the azimuthal decorrelation between jets with pseudorapidity separation up to five units are presented. The data were taken at the Fermi National Accelerator Laboratory during the 1992-1993 collider run with the D{null} detector using {ital p{anti p}} collisions at center-of-mass energy {radical}{ital s} = 1.8 TeV. These results are compared to next-to-leading order (NLO) QCD predictions and to two leading-log approximations (LLA) where the leading terms are resummed to all orders in {alpha}{sub s}. The final state jets as predicted by NLO QCD show less azimuthal decorrelation than the data. The parton showering LLA Monte Carlo HERWIG describes the data well; an analytical LLA calculation based on Balitsky-Faclin-Kuraev-Lipatov resummation predicts more decorrelation than is present in the data.

  15. Performance study of glass RPC detectors for INO-ICAL experiment

    NASA Astrophysics Data System (ADS)

    Gaur, Ankit; Kumar, Ashok; Naimuddin, Md.

    2017-02-01

    Resistive plate chamber (RPC) detectors are known for their excellent timing and good spatial resolution which make them favorable candidate for tracking and triggering in many high energy physics experiments. The Iron Calorimeter (ICAL) detector at India-based Neutrino Observatory (INO) is one such experiment which will use RPCs as an active detector element. The ICAL experiment is designed to study atmospheric neutrinos and various issues related with neutrino physics. The INO-ICAL has geometry that utilizes about 29,000 RPCs of 2×2 m2 in size, interleaved between thick iron plates, producing muons via the interaction of atmospheric neutrinos with iron. The tracking information of the muons will be extracted from the two-dimensional readout of the RPCs and its position in respective layers along with the upward and downward directionality determined from the timing information. As a result, a precise measurement of timing response of these RPC detectors is quite important. Furthermore, to design readout system for the ICAL detector, induced signal study and charge information is needed as well. In this paper, we present a detailed timing and charge spectra study for various glass RPC candidates. We also report the effect of various gas compositions on the timing and charge spectra of these RPC detectors.

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

    PubMed Central

    Cho, H-M; Ding, H; Ziemer, BP; Molloi, S

    2014-01-01

    Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using X-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for X-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm2 in detection area. The angular dependence of X-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded X-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of X-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of X-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic X-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the X-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory. PMID:25369288

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

    PubMed

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

    2014-12-07

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

  18. Study of solid-conversion gaseous detector based on GEM for high energy X-ray industrial CT.

    PubMed

    Zhou, Rifeng; Zhou, Yaling

    2014-01-01

    The general gaseous ionization detectors are not suitable for high energy X-ray industrial computed tomography (HEICT) because of their inherent limitations, especially low detective efficiency and large volume. The goal of this study was to investigate a new type of gaseous detector to solve these problems. The novel detector was made by a metal foil as X-ray convertor to improve the conversion efficiency, and the Gas Electron Multiplier (hereinafter "GEM") was used as electron amplifier to lessen its volume. The detective mechanism and signal formation of the detector was discussed in detail. The conversion efficiency was calculated by using EGSnrc Monte Carlo code, and the transport course of photon and secondary electron avalanche in the detector was simulated with the Maxwell and Garfield codes. The result indicated that this detector has higher conversion efficiency as well as less volume. Theoretically this kind of detector could be a perfect candidate for replacing the conventional detector in HEICT.

  19. Intercomparison of passive radon-detectors under field conditions in epidemiological studies

    SciTech Connect

    Kreienbrock, L. ); Poffijn, A. ); Tirmarche, M. ); Feider, M. ); Kies, A. ); Darby, S.C. )

    1999-05-01

    The Ardennes and Eifel region is a geologically distinct area covering parts of Germany, Belgium, France, and Luxembourg where enhanced concentrations of radon occur in some houses and other buildings. An international case-control study is being conducted to examine the role of radon in the etiology of lung cancer in this area. The radon detectors used are issued by different laboratories involving a variety of detector types and processes. A series of intercomparisons in houses was therefore conducted under similar conditions of exposure in the field. In most situations the different detectors gave similar results. Nevertheless, in some situations open and closed detectors yielded different results. Therefore, estimates of radon exposure have to be adjusted if results are to be pooled.

  20. Study of the counting rate capability of MRPC detectors built with soda lime glass

    NASA Astrophysics Data System (ADS)

    Forster, R.; Margoto Rodríguez, O.; Park, W.; Rodríguez Rodríguez, A.; Williams, M. C. S.; Zichichi, A.; Zuyeuski, R.

    2016-09-01

    We report the results of three MRPC detectors built with soda lime glass and tested in the T10 beam line at CERN. The detectors consist of a stack of 280 μm thick glass sheets with 6 gaps of 220 μm . We built two identical MRPCs, except one had the edges of glass treated with resistive paint. A third detector was built with one HV electrode painted as strips. The detectors' efficiency and time resolution were studied at different particle flux in a pulsed beam environment. The results do not show any improvement with the painted edge technique at higher particle flux. We heated the MRPCs up to 40 °C to evaluate the influence of temperature in the rate capability. Results from this warming has indicated an improvement on the rate capability. The dark count rates show a significant dependence with the temperature.

  1. A simulation study on the focal plane detector of the LAUE project

    NASA Astrophysics Data System (ADS)

    Khalil, M.; Frontera, F.; Caroli, E.; Virgilli, E.; Valsan, V.

    2015-06-01

    The LAUE project, supported by the Italian Space Agency (ASI), is devoted to the development of a long focal length (even 20 m or longer) Laue lens for gamma ray astronomy between 80 and 600 keV. These lenses take advantage of Bragg diffraction to focus radiation onto a small spot drastically improving the signal to noise ratio as well as reducing the required size of the detector significantly. In this paper we present a Monte-Carlo simulation study with MEGALIB to optimize, for space applications, the detector size to achieve high detection efficiency, and to optimize the position resolution of the detector to reconstruct the Point Spread Function of the lens considered for the LAUE project. Then we will show simulations, using the SILVACO semiconductor simulation toolkit, on the optimized detector to estimate its capacitance per channel and depletion voltage. In all of the simulations, two materials were compared; a low density material (Silicon) and a high density material (Germanium).

  2. Computed tomography dosimetry with high-resolution detectors commonly used in radiotherapy - an energy dependence study.

    PubMed

    Liebmann, Mario; Poppe, Bjoern; von Boetticher, Heiner

    2015-09-08

    New methods of dosimetry in computed tomography (CT) X-ray fields require the use of high-resolution detectors instead of pencil-type ionization chambers typically used for CT dose index (CTDI) measurements. This paper presents a study on the suitability of a wide range of ionization chambers, diodes, and a two-dimensional detector array, used primarily in radiation therapy, for CT and cone-beam CT dosimetry. Specifically, the energy dependence of these detectors from 50 kVp up to 125 kVp is reported. All measurements were performed in reference to a calibrated diode for use in this energy region. The radiation quality correction factors provided by the manufacturer were used, depending on the measured half-value layer (HVL) for the particular X-ray beam. Our study demonstrated the general usability of thimble ionization chambers. These thimble ionization chambers showed a maximum variation in energy response of 5%. Ionization chambers with even smaller sensitive volume, and which exhibit similar variation in energy dependence, can be used if higher spatial resolution is required. Furthermore, the investigated detectors are better suited for dosimetry at CT and CBCT units than conventional large volume or flat detectors, due to their rotational symmetry. Nevertheless, a flat detector can be used for certain measurement tasks, such as the acquisition of percent depth-dose curves or beam profiles for nonrotating beams, which are important for beam characterization.

  3. Investigation of the optimal detector arrangement for the helmet-chin PET - A simulation study

    NASA Astrophysics Data System (ADS)

    Ahmed, Abdella M.; Tashima, Hideaki; Yoshida, Eiji; Yamaya, Taiga

    2017-06-01

    High sensitivity and high spatial resolution dedicated brain PET scanners are in high demand for early diagnosis of neurodegenerative diseases and studies of brain functions. To meet the demand, we have proposed the helmet-chin PET geometry which has a helmet detector and a chin detector. Our first prototype scanner used 54 4-layer depth-of-interaction (DOI) detectors. The helmet detector of the scanner had three detector rings with different radii arranged on a surface of a hemisphere (with a radius of 126.5 mm) and a top cover detector. Therefore, in this study, for our next development, we propose a spherical arrangement, in which the central axis of each detector points toward the center of the hemisphere, and we optimize the size of the detector crystal block to be arranged on the helmet detector. We simulate the spherical arrangement with the optimized crystal block size and compare its imaging performance with the multi-ring arrangement, which has a similar detector arrangement to that of our first prototype. We conduct Monte Carlo simulation to model the scanners having the 4-layer DOI detectors which consist of LYSO crystals. A dead space of 2 mm is assumed on each side of the crystal blocks such as for wrapping. The size of the crystal block is varied from 4×4 mm2 to 54×54 mm2 while fixing the thickness of the crystal block to 20 mm. We find that the crystal block sized at 42×42 mm2 has the highest sensitivity for a hemispherical phantom. The comparison of the two arrangements with the optimized crystal blocks show that, for the same number of crystal blocks, the spherical arrangement has 17% higher sensitivity for the hemispherical phantom than the multi-ring arrangement. We conclude that the helmet-chin PET with the spherical arrangement constructed from the crystal block sized at 42×42×20 mm3 has better imaging performance especially at the upper part of the brain compared to the multi-ring arrangement while keeping similar spatial resolution

  4. Analytical expression for position sensitivity of linear response beam position monitor having inter-electrode cross talk

    NASA Astrophysics Data System (ADS)

    Kumar, Mukesh; Ojha, A.; Garg, A. D.; Puntambekar, T. A.; Senecha, V. K.

    2017-02-01

    According to the quasi electrostatic model of linear response capacitive beam position monitor (BPM), the position sensitivity of the device depends only on the aperture of the device and it is independent of processing frequency and load impedance. In practice, however, due to the inter-electrode capacitive coupling (cross talk), the actual position sensitivity of the device decreases with increasing frequency and load impedance. We have taken into account the inter-electrode capacitance to derive and propose a new analytical expression for the position sensitivity as a function of frequency and load impedance. The sensitivity of a linear response shoe-box type BPM has been obtained through simulation using CST Studio Suite to verify and confirm the validity of the new analytical equation. Good agreement between the simulation results and the new analytical expression suggest that this method can be exploited for proper designing of BPM.

  5. Characterization of Bias Effects on Sodium Iodide Detectors for Reaction Studies

    NASA Astrophysics Data System (ADS)

    Hertz-Kintish, Daniel; Cizewski, Jolie; Carls, Alex; Chipps, Kelly; Pain, Steve; Thompson, Paul; Waddell, Deion

    2015-10-01

    Nuclear physics reaction and decay studies with radioactive ion beams need high-efficiency detectors for all radiations, including gamma rays. Sodium iodide crystals are well established as γ-ray detectors, favored for many years for their high efficiency and relatively low cost. Several thallium-activated sodium iodide detectors have been characterized with γ-ray sources in order for their properties to be well understood and that they may be properly utilized in future experiments. These detectors could be used in nuclear reaction measurements with radioactive ion beams to measure coincident γ-rays and light charged particles. My contribution was a careful analysis of the effects of the level of bias on the photomultiplier tubes to show how the efficiency and resolution of these detectors can be optimized by controlling this voltage. An analysis of gain shifts due to temperature variations, the photomultiplier aging process, and the bias was also included. This presentation would summarize the status of the characterization of the NaI detectors. This work is supported in part by the U.S. Department of Energy and National Science Foundation.

  6. A Comprehensive Study of the Large Underground Xenon Detector

    NASA Astrophysics Data System (ADS)

    Woods, Michael Austin

    The Large Underground Xenon (LUX) dark matter search experiment operates a time projection chamber constructed of 370 kg of xenon, currently installed in the Homestake gold mine. The goal of the experiment is to detect Weakly Interacting Massive Particles (WIMPs). Novel calibration methods for this uniquely large detector are discussed. Background events due to standard model physics processes including cosmogenically activated xenon, alpha emission, and neutron production are shown to be negligible in recent 85 day WIMP search data. The LUX Monte Carlo simulation includes a new physical model, the Nobel Element Simulation Technique (NEST), for scintillation and ionization. NEST describes energy-, particle-, field- and medium-dependent behavior of a charge recombination model. A simulated data acquisition chain that bridges the gap between simulation and data has been developed to permit full testing of the analysis tools employed by LUX. Signal generation by cumulative photon responses are described algorithmically. Computational optimization has been performed to decrease processing time by a factor of fifty. A new technique for event depth estimation using machine learning and image analysis is introduced. Variable length waveforms are converted to fixed dimension field maps for use in machine learning. A support vector machine trained against pulse shapes with known depth successfully regressed depth without direct measurement of highly variable pulse widths. The world's most stringent limits on spin-independent WIMP-nucleon scattering cross section are presented.

  7. Charge collection in silicon strip detectors

    SciTech Connect

    Kraner, H.W.; Beuttenmuller, R.; Ludlam, T.; Hanson, A.L.; Jones, K.W.; Radeka, V.; Heijne, E.H.M.

    1982-11-01

    The use of position sensitive silicon detectors as very high resolution tracking devices in high energy physics experiments has been a subject of intense development over the past few years. Typical applications call for the detection of minimum ionizing particles with position measurement accuracy of 10 ..mu..m in each detector plane. The most straightforward detector geometry is that in which one of the collecting electrodes is subdivided into closely spaced strips, giving a high degree of segmentation in one coordinate. Each strip may be read out as a separate detection element, or, alternatively, resistive and/or capacitive coupling between adjacent strips may be exploited to interpolate the position via charge division measrurements. With readout techniques that couple several strips, the numer of readout channels can, in principle, be reduced by large factors without sacrificing the intrinsic position accuracy. The testing of individual strip properties and charge division between strips has been carried out with minimum ionizing particles or beams for the most part except in one case which used alphs particless scans. This paper describes the use of a highly collimated MeV proton beam for studies of the position sensing properties of representative one dimensional strip detectors.

  8. Studying the Sun's Nuclear Furnace with a Neutrino Detector Spacecraft in Close Solar Orbit

    NASA Astrophysics Data System (ADS)

    Solomey, Nickolas

    2016-05-01

    A neutrino based detector in close solar orbit would have a neutrino flux 10,000x or more larger flux than on Earth and a smaller detector able to handle high rates with exception energy resolution could be used. We have studied the idea of operating such an experiment in close solar orbits that takes it off the ecliptic plane and in a solar orbit where the distance from the Sun will change distance. This neutrino detector on a space craft could do Solar Astrophysics studying the Solar nuclear furnace, basic nuclear physics and elementary particle physics; some of these ideas are new unique science that can only be preformed from a spacecraft. The harsh environment provides many challenges but if such a detector could be made to work it can be the next major step in this science study. How a small segmented detector can operate and preform in this environment to detect solar neutrinos will be elaborated upon using a combination of signal strength, fast signal timing, shielding and segmentation.

  9. Study of resistive micromegas detectors in a mixed neutron and photon radiation environment

    NASA Astrophysics Data System (ADS)

    Alexopoulos, T.; Iakovidis, G.; Tsipolitis, G.

    2012-05-01

    The Muon ATLAS Micromegas Activity (MAMMA) focuses on the development and testing of large-area muon detectors based on the bulk-Micromegas technology. These detectors are candidates for the upgrade of the ATLAS Muon System in view of the luminosity upgrade of Large Hadron Collider at CERN (sLHC). They will combine trigger and precision measurement capability in a single device. A novel protection scheme using resistive strips above the readout electrode has been developed. The response and sparking properties of resistive Micromegas detectors were successfully tested in a mixed (neutron and gamma) high radiation environment supplied by the Tandem accelerator at the N.C.S.R. Demokritos in Athens. Monte-Carlo studies have been employed to study the effect of 5.5 MeV neutrons impinging on Micromegas detectors. The response of the Micromegas detectors on the photons originating from the inevitable neutron inelastic scattering on the surrounding materials of the experimental facility was also studied.

  10. A novel phoswich imaging detector for simultaneous beta and coincidence-gamma imaging of plant leaves.

    PubMed

    Wu, Heyu; Tai, Yuan-Chuan

    2011-09-07

    To meet the growing demand for functional imaging technology for use in studying plant biology, we are developing a novel technique that permits simultaneous imaging of escaped positrons and coincidence gammas from annihilation of positrons within an intake leaf. The multi-modality imaging system will include two planar detectors: one is a typical PET detector array and the other is a phoswich imaging detector that detects both beta and gamma. The novel phoswich detector is made of a plastic scintillator, a lutetium oxyorthosilicate (LSO) array, and a position sensitive photomultiplier tube (PS-PMT). The plastic scintillator serves as a beta detector, while the LSO array serves as a gamma detector and light guide that couples scintillation light from the plastic detector to the PMT. In our prototype, the PMT signal was fed into the Siemens QuickSilver electronics to achieve shaping and waveform sampling. Pulse-shape discrimination based on the detectors' decay times (2.1 ns for plastic and 40 ns for LSO) was used to differentiate beta and gamma events using the common PMT signals. Using our prototype phoswich detector, we simultaneously measured a beta image and gamma events (in single mode). The beta image showed a resolution of 1.6 mm full-width-at-half-maximum using F-18 line sources. Because this shows promise for plant-scale imaging, our future plans include development of a fully functional simultaneous beta-and-coincidence-gamma imager with sub-millimeter resolution imaging capability for both modalities.

  11. A novel phoswich imaging detector for simultaneous beta and coincidence-gamma imaging of plant leaves

    NASA Astrophysics Data System (ADS)

    Wu, Heyu; Tai, Yuan-Chuan

    2011-09-01

    To meet the growing demand for functional imaging technology for use in studying plant biology, we are developing a novel technique that permits simultaneous imaging of escaped positrons and coincidence gammas from annihilation of positrons within an intake leaf. The multi-modality imaging system will include two planar detectors: one is a typical PET detector array and the other is a phoswich imaging detector that detects both beta and gamma. The novel phoswich detector is made of a plastic scintillator, a lutetium oxyorthosilicate (LSO) array, and a position sensitive photomultiplier tube (PS-PMT). The plastic scintillator serves as a beta detector, while the LSO array serves as a gamma detector and light guide that couples scintillation light from the plastic detector to the PMT. In our prototype, the PMT signal was fed into the Siemens QuickSilver electronics to achieve shaping and waveform sampling. Pulse-shape discrimination based on the detectors' decay times (2.1 ns for plastic and 40 ns for LSO) was used to differentiate beta and gamma events using the common PMT signals. Using our prototype phoswich detector, we simultaneously measured a beta image and gamma events (in single mode). The beta image showed a resolution of 1.6 mm full-width-at-half-maximum using F-18 line sources. Because this shows promise for plant-scale imaging, our future plans include development of a fully functional simultaneous beta-and-coincidence-gamma imager with sub-millimeter resolution imaging capability for both modalities.

  12. New mechanism that accounts for position sensitivity of saccades evoked in response to stimulation of superior colliculus.

    PubMed

    Moschovakis, A K; Dalezios, Y; Petit, J; Grantyn, A A

    1998-12-01

    New mechanism that accounts for position sensitivity of saccades evoked in response to stimulation of superior colliculus. J. Neurophysiol. 80: 3373-3379, 1998. Electrical stimulation of the feline superior colliculus (SC) is known to evoke saccades whose size depends on the site stimulated (the "characteristic vector" of evoked saccades) and the initial position of the eyes. Similar stimuli were recently shown to produce slow drifts that are presumably caused by relatively direct projections of the SC onto extraocular motoneurons. Both slow and fast evoked eye movements are similarly affected by the initial position of the eyes, despite their dissimilar metrics, kinematics, and anatomic substrates. We tested the hypothesis that the position sensitivity of evoked saccades is due to the superposition of largely position-invariant saccades and position-dependent slow drifts. We show that such a mechanism can account for the fact that the position sensitivity of evoked saccades increases together with the size of their characteristic vector. Consistent with it, the position sensitivity of saccades drops considerably when the contribution of slow drifts is minimal as, for example, when there is no overlap between evoked saccades and short-duration trains of high-frequency stimuli.

  13. Photoneutron depth dose equivalent distributions in high-energy X-ray medical accelerators by a novel position-sensitive dosimeter.

    PubMed

    Hakimi, Amir; Sohrabi, Mehdi

    2017-04-01

    The purpose of this study was to; (1) investigate employing a novel position-sensitive mega-size polycarbonate (MSPC) dosimeter for photoneutron (PN) depth, profile and dose equivalent distributions studies in a multilayer polyethylene phantom in a Siemens ONCOR accelerator, and (2) develop depth dose equivalent distribution matrix data at different depths and positions of the phantom for patient PN dose equivalent determination and in particular for PN secondary cancer risk estimation. Position-sensitive MSPC dosimeters were successfully exposed at 9 different depths of the phantom in a 10×10cm(2) X-ray field. The dosimeters were processed in mega-size electrochemical chambers at optimum conditions. Each MSPC dosimeter was placed at a known phantom depth for PN depth dose equivalents and profiles on transverse, longitudinal and diagonal axes and isodose equivalent distribution studies in and out of the X-ray beam. PN dose equivalent distributions at any depth showed the highest value at the beam central axis and decreases as the distance increases. PN dose equivalent at any position studied in the axes has a maximum value on the phantom surface which decreases as depth increases due to flux reduction by multi-elastic scattering interactions. Extensive PN dose equivalent matrix data at different depths and positions in the phantom were determined. The position-sensitive MSPC dosimeters proved to be highly efficient for PN depth, profile and isodose equivalent distribution studies. The extensive data obtained highly assists for determining PN dose equivalent of a patient undergoing high-energy X-ray therapy and for PN secondary cancer risk estimation. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

    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%.

  15. Imaging and spectroscopic performance studies of pixellated CdTe Timepix detector

    NASA Astrophysics Data System (ADS)

    Maneuski, D.; Astromskas, V.; Fröjdh, E.; Fröjdh, C.; Gimenez, E. N.; Marchal, J.; O'Shea, V.; Stewart, G.; Tartoni, N.; Wilhelm, H.; Wraight, K.; Zain, R. M.

    2012-01-01

    In this work the results on imaging and spectroscopic performances of 14 × 14 × 1 mm CdTe detectors with 55 × 55 μm and 110 × 110 μm pixel pitch bump-bonded to a Timepix chip are presented. The performance of the 110 × 110 μm pixel detector was evaluated at the extreme conditions beam line I15 of the Diamond Light Source. The energy of X-rays was set between 25 and 77 keV. The beam was collimated through the edge slits to 20 μm FWHM incident in the middle of the pixel. The detector was operated in the time-over-threshold mode, allowing direct energy measurement. Energy in the neighbouring pixels was summed for spectra reconstruction. Energy resolution at 77 keV was found to be ΔE/E = 3.9%. Comparative imaging and energy resolution studies were carried out between two pixel size detectors with a fluorescence target X-ray tube and radioactive sources. The 110 × 110 μm pixel detector exhibited systematically better energy resolution in comparison to 55 × 55 μm. An imaging performance of 55 × 55 μm pixellated CdTe detector was assessed using the Modulation Transfer Function (MTF) technique and compared to the larger pixel. A considerable degradation in MTF was observed for bias voltages below -300 V. Significant room for improvement of the detector performance was identified both for imaging and spectroscopy and is discussed.

  16. Performance improvement of small gamma camera using NaI(Tl) plate and position sensitive photo-multiplier tubes.

    PubMed

    Jeong, Myung Hwan; Choi, Yong; Chung, Yong Hyun; Song, Tae Yong; Jung, Jin Ho; Hong, Key Jo; Min, Byung Jun; Choe, Yearn Seong; Lee, Kyung-Han; Kim, Byung-Tae

    2004-11-07

    The purpose of this study was to improve the performance of a small gamma camera, utilizing a NaI(Tl) plate and a 5" position sensitive PMT. We attempted to build a NaI(Tl) plate crystal system which retained all its advantages, while at the same time integrating some of the advantages inherent in an array-type scintillation crystal system. Flood images were obtained with a lead hole mask, and position mapping was performed by detecting hole positions in the flood image. Energy calibration was performed using the energy spectra obtained from each hole position. Flood correction was performed using a uniformity correction table containing the relative efficiency of each image element. The spatial resolution was improved about 16% after correction at the centre field of view. Resolution deterioration at the outer field of view (OFOV) was considerably ameliorated, from 6.7 mm to 3.2 mm after correction. The sensitivity at the OFOV was also increased after correction, from 0.7 cps microCi(-1) to 2.0 cps microCi(-1). The correction also improved uniformity, from 5.2% to 2.1%, and linearity, from 0.5 mm to 0 mm. The results of this study indicate that the revised correction method can be employed to considerably improve the performance of a small gamma camera using a NaI(Tl) plate-type crystal. This method also provides high spatial resolution and linearity, like array-type crystals do, while retaining the specific advantages of plate-type crystals.

  17. Preliminary studies of PQS PET detector module for dose verification of carbon beam therapy

    NASA Astrophysics Data System (ADS)

    Kim, H.-I.; An, S. Jung; Lee, C. Y.; Jo, W. J.; Min, E.; Lee, K.; Kim, Y.; Joung, J.; Chung, Y. H.

    2014-05-01

    PET imaging can be used to verify dose distributions of therapeutic particle beams such as carbon ion beams. The purpose of this study was to develop a PET detector module which was designed for an in-beam PET scanner geometry integrated into a carbon beam therapy system, and to evaluate its feasibility as a monitoring system of patient dose distribution. A C-shaped PET geometry was proposed to avoid blockage of the carbon beam by the detector modules. The proposed PET system consisted of 14 detector modules forming a bore with 30.2 cm inner diameter for brain imaging. Each detector module is composed of a 9 × 9 array of 4.0 mm × 4.0 mm × 20.0 mm LYSO crystal module optically coupled with four 29 mm diameter PMTs using Photomultiplier-quadrant-sharing (PQS) technique. Because the crystal pixel was identified based upon the distribution of scintillation lights of four PMTs, the design of the reflector between crystal elements should be well optimized. The optical design of reflectors was optimized using DETECT2000, a Monte Carlo code for light photon transport. A laser-cut reflector set was developed using the Enhanced Specular Reflector (ESR, 3M Co.) mirror-film with a high reflectance of 98% and a thickness of 0.064 mm. All 81 crystal elements of detector module were identified. Our result demonstrates that the C-shaped PET system is under development and we present the first reconstructed image.

  18. Study of the response of PICASSO bubble detectors to neutron irradiation

    NASA Astrophysics Data System (ADS)

    Marlisov, Daniiar

    The objective of this work was to simulate the PICASSO experiment and to study the detector response to neutron irradiation. The results of the simulation show the rock neutron rate to be 1-2 neutrons/day for the setup used until 2009 and less than 0.1 neutrons/day for the setup used after 2010. The shielding efficiency was calculated to be 98% and 99.6% for the two setups respectively. The detector response to an AmBe source was simulated. Neutron rates differ for two AmBe source spectra from the literature. The observed data rate is in agreement with the rate from the simulation. The detector stability was examined and found to be stable. The source position and orientation affect the detector efficiency creating a systematic uncertainity on the order of 10-35%. This uncertainity was eliminated with a source holder. The localisation of recorded events inside the detector and the simulated neutron distribution agree.

  19. Design, development and performance study of six-gap glass MRPC detectors

    NASA Astrophysics Data System (ADS)

    Devi, M. M.; Mondal, N. K.; Satyanarayana, B.; Shinde, R. R.

    2016-12-01

    The multigap resistive plate chambers (MRPCs) are gas ionization detectors with multiple gas sub-gaps made of resistive electrodes. The high voltage (HV) is applied on the outer surfaces of outermost resistive plates only, while the interior plates are left electrically floating. The presence of multiple narrow sub-gaps with high electric field results in faster signals on the outer electrodes, thus improving the detector's time resolution. Due to their excellent performance and relatively low cost, the MRPC detector has found potential application in time-of-flight (TOF) systems. Here we present the design, fabrication, optimization of the operating parameters such as the HV, the gas mixture composition, and, performance of six-gap glass MRPC detectors of area 27 cm × 27 cm, which are developed in order to find application as trigger detectors, in TOF measurement etc. The design has been optimized with unique spacers and blockers to ensure a proper gas flow through the narrow sub-gaps, which are 250 μm wide. The gas mixture consisting of R134A, Isobutane and SF6, and the fraction of each constituting gases has been optimized after studying the MRPC performance for a set of different concentrations. The counting efficiency of the MRPC is about 95% at 17.9 kV. At the same operating voltage, the time resolution, after correcting for the walk effect, is found to be about 219 ps.

  20. Experimental and numerical study of thin fragments protection for radiographic detectors

    NASA Astrophysics Data System (ADS)

    Bozier, Olivier; Counilh, Denis; Gillot, Fabrice; Adolf, Lise-Marie; Silvin, Pascale; Rambert, Nicolas; Hebert, David; Bertron, Isabelle

    2015-06-01

    To perform a non-intrusive measurement on a pyrotechnic setup, we usually use radiography. But due to blast and fragments, the X-ray generator head and the detectors of the radiographic chain must be protected. Since the detector holds the data we want to collect, he cannot be sacrificed. The constitution of detector shielding is therefore an essential part of a radiographic chain. The choice of shielding should take into account two conflicting needs. On one hand, shielding must be sufficiently resistant to protect the detector from the blast and fragments generated. On the other hand, it should be thin enough in order to attenuate as little as possible the radiographic signal. We carried out an experimental campaign to test the performances of various shieldings. Cylindrical projectiles of various masses (from 20g to 40g) and aspect ratios (length to diameter ratio from 0.1 to 1) that are representative fragments, have been launched with a gas gun with different initial velocities (from 1500m/s up to 2000m/s). Multiple shielding configurations have been tested. They were assemblies of successive steel, aluminum and B4C plates. Combined with a numerical study, we optimize disposition and thicknesses of the plates which fulfils our requirements in terms of detector protection and radiographic measurement.

  1. [Study on the best detector-distance of noninvasive biochemical examination by Monte Carlo simulation].

    PubMed

    Dong, Yan-Fei; Lu, Qi-Peng; Ding, Hai-Quan; Gao, Hong-Zhi

    2014-04-01

    The present paper studies the best detector-distance to improve the near-infrared spectrum signal intensity of the dermis layer and eliminate the interference of the epidermis and subcutaneous layer. First, we analyzed the organizational structure of the skin and calculated the tissue optical parameters of different layers. And we established the Monte Carlo model with the example of glucose absorption peak at 2 270 nm. Then, we used the Monte Carlo method to simulate the light transmission rules in the skin, obtaining the average path length, the average visit depth and the fractions of absorbed energy at each layer with the change in critical angle and detector-distance. The results show that when the photons are incident at an angle less than 45 degrees, you can ignore the effect of the incident angle on photon transmission path, and when the detector-distance is 1 mm, the fraction of absorbed photon energy by the dermis layer is the largest, while it can ensure more energy received by detector. We determined that the best detector-distance is 1mm, which successfully avoids the interference of the epidermis spectral information and obtains large amounts of blood in the dermis layer, which is conducive to the near-infrared non-invasive measurement of biochemical components and the subsequent experiments.

  2. Nucifer: A small electron-antineutrino detector for fundamental and safeguard studies

    SciTech Connect

    Letourneau, A.; Bui, V. M.; Fallot, M.; Giot, L.; Martino, J.; Porta, A.; Varignon, C.; Yermia, F.

    2011-07-01

    The Nucifer detector will be deployed in the next few months at the Osiris research reactor in France. Nucifer is a 1-ton Gd-doped liquid scintillator detector devoted to reactor antineutrino studies. It will be installed 7 m away from the compact core of the Osiris reactor. The design of such small volume detector has been focused on high detection efficiency and good background rejection. Over the last decades, our understanding of the neutrino properties has been improved and allows today the possibility to apply the detection of antineutrinos to automatic and to non intrusively survey nuclear power plant. This has triggered the interest of the International Atomic Energy Agency (IAEA), which is interested by developing new safeguard techniques for next generation reactors. The sensitivity of such technique has to be proved and demonstrated. On the other hand there is still some issues in our understanding of the neutrino properties as the observed deficit in the antineutrino rate at short distances (< 100 m) that can not be explained by oscillations in the 3-flavors neutrino model. If a global systematic error is rejected, such anomaly opens the door to new physic that can be assessed with small detectors placed close to the core. Here we review the Nucifer detector in this context and the tests we are performing. (authors)

  3. Detector and Electronic Developments for Low Energy Multi Particle Break-up Studies.

    NASA Astrophysics Data System (ADS)

    Tengblad, Olof

    2007-11-01

    The study of excited states of unbound light nuclei includes the simultaneous detection of several charge particles emitted with very low energy. This puts several constrains on the detection system to be used. For the detectors, high segmentation is needed to be able to detect several coincident particles without an exponential drop in efficiency. The high segmentation of the detectors leads to experiments with an increased amount of electronic channels. For very dedicated experiment integrated electronic chips can be prepared, but in many cases where the detector set-up are frequently being changed, one still have to rely on more traditional analogue electronic circuits. News in the field of charge particle detection will be discussed.

  4. Study on the performance of electromagnetic particle detectors of LHAASO-KM2A

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongquan; Hou, Chao; Cao, Zhen; Chang, Jingfan; Feng, Cunfeng; Hanapia, Erlan; Gong, Guanghua; Liu, Jia; Lv, Hongkui; Sheng, Xiangdong; Zhang, Shaoru; Zhu, Chengguang

    2017-02-01

    The electromagnetic particle detectors (EDs) for one square kilometer detector array (KM2A) of large high altitude air shower observation (LHAASO) are designed to measure the densities and arrival times of secondary particles in extensive air showers (EASs). ED is a type of plastic scintillator detector with an active area of 1 m2. This study investigates the design and performance of prototype ED. Approximately 20 photoelectrons are collected by the 1st dynode of a photomultiplier tube (PMT). The prototype ED exhibited good detection efficiency and time resolution. The detection for the wide dynamic particle density varying from 1 to 10 000 particles/m2 is realized with the design of the PMT divider for the readout of both the anode and 6th dynode.

  5. Study of ageing and fading in CR-39 detectors for different storage conditions.

    PubMed

    Franci, Daniele; Aureli, Tommaso; Cardellini, Francesco

    2015-12-01

    The aim of this study was to investigate the effect of ageing and fading on PADC detector response, as a function of the storage time and temperature. Several groups of CR-39 detectors provided by Radosys, Ltd. were exposed at the reference radon chamber of the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, at the ENEA centre in Casaccia. The results indicate that low-temperature storage inhibits the effect of both ageing and fading. Finally, the overall reduction in CR-39 sensitivity due to the combined ageing/fading effect was estimated. In particular, the sensitivity of the detectors continuously exposed in air at room temperature over 6 and 3 months was reduced, respectively, by 7.5 and 4 %. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. GEM detectors for WEST and potential application for heavy impurity transport studies

    NASA Astrophysics Data System (ADS)

    Mazon, D.; Jardin, A.; Coston, C.; Faisse, F.; Chernyshova, M.; Czarski, T.; Kasprowicz, G.; Wojenski, A.

    2016-08-01

    In tokamaks equipped with metallic walls and in particular tungsten, the interplay between particle transport and MagnetoHydroDynamic (MHD) activity might lead to impurities accumulation and finally to sudden plasma termination called disruption. Studying such transport phenomena is thus essential if stationary discharges are to be achieved. On WEST a new SXR diagnostic is developed in collaboration with IPPLM (Poland) and the Warsaw University of Technology, based on a triple Gas Electron Multiplier (GEM) detector. Potential application of the WEST GEM detectors for tomographic reconstruction and subsequent transport analysis is presented.

  7. First Results of Small Animal Imaging Spect Detector for Cardiovascular Disease Studies on Mice

    NASA Astrophysics Data System (ADS)

    Magliozzi, M. L.; Ballerini, M.; Cisbani, E.; Colilli, S.; Cusanno, F.; Fratoni, R.; Garibaldi, F.; Giuliani, F.; Gricia, M.; Lucentini, M.; Santavenere, F.; Torrioli, S.; Veneroni, P.; Majewsky, S.; Mok, S. P. G.; Tsui, B. M. W.; Wang, Y.; Marano, G.; Musumeci, M.; Palazzesi, S.; Ciccariello, G.; de Vincentis, G.; Accorsi, R.

    2008-06-01

    We have developed a compact, open, Dual Head pinhole SPECT system for high resolution molecular imaging with radionuclides of mice, dedicated mainly to preclinical study of stem cells capability to recover myocardial infarction. The gamma detector is made of pinhole tungsten collimators, pixellated scintillators, matrix of multi-anode PMTs and individual channel readout. Measurements have been performed on phantoms and live mice devoted initially to test and calibrate the system and to optimize protocols. The implemented system and the first results will be presented, demonstrating the effectiveness of our dedicated SPECT detector for small animal imaging.

  8. Study Of Boosted W-Jets And Higgs-Jets With the SiFCC Detector

    SciTech Connect

    Yu, Shin-Shan; Chekanov, Sergei; Gray, Lindsey; Kotwal, Ashutosh; Sen, Sourav; Tran, Nhan Viet

    2016-11-04

    We study the detector performance in the reconstruction of hadronically-decaying W bosons and Higgs bosons at very high energy proton colliders using a full GEANT4 simulation of the SiFCC detector. The W and Higgs bosons carry transverse momentum in the multi-TeV range, which results in collimated decay products that are reconstructed as a single jet. We present a measurement of the energy response and resolution of boosted W-jets and Higgs-jets and show the separation of two sub-jets within the boosted boson jet.

  9. J-PET detector system for studies of the electron-positron annihilations

    NASA Astrophysics Data System (ADS)

    Pawlik-Niedźwiecka, M.; Khreptak, O.; Gajos, A.; Wieczorek, A.; Alfs, D.; Bednarski, T.; Białas, P.; Curceanu, C.; Czerwiński, E.; Dulski, K.; Głowacz, B.; Gupta-Sharma, N.; Gorgol, M.; Hiesmayr, B. C.; Jasińska, B.; Kamińska, D.; Korcyl, G.; Kowalski, P.; Krzmień, W.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedźwiecki, Sz.; Raczyński, L.; Rudy, Z.; Silarski, M.; Wiślicki, W.; Zgardzińska, B.; Zieliński, M.; Moskal, P.

    2016-11-01

    Jagiellonian Positron Emission Tomograph (J-PET) has been recently constructed at the Jagiellonian University as a prototype of a cost-effective scanner for the metabolic imaging of the whole human body. J-PET detector is optimized for the measurement of momentum and polarization of photons from the electron-positron annihilations. It is built out of strips of plastic scintillators, forming three cylindrical layers. As detector of gamma quanta it will be used for studies of discrete symmetries and multiparticle entanglement of photons originating from the decays of ortho-positronium atoms.

  10. A Feasibility Study of Hyperon and Hypernuclei Reconstruction at NICA with BM@N Detector

    NASA Astrophysics Data System (ADS)

    Suvarieva, D.; Ilieva, M.; Kapishin, M.; Kolesnikov, V.; Vasendina, V.; Zinchenko, A.

    2016-01-01

    Heavy strange objects (hyperons and hypernuclei) could provide essential signatures of the excited and compressed baryonic matter. Their reconstruction and identification should be one of the most important tasks of any experiment with heavy ions. At NICA, it is planned to study hyperons both in the collider mode (MPD detector) and the fixed- target one (BM@N setup). The results on Λ, Ξ- hyperon and 3ΛH hypernuclei reconstruction in Monte Carlo simulated event samples of gold-gold collisions with the BM@N detector are presented.

  11. Prototyping and performance study of a single crystal diamond detector for operation at high temperatures

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Kumar, Arvind; Topkar, Anita; Das, D.

    2017-06-01

    Prototype single crystal diamond detectors with different types of metallization and post metallization treatment were fabricated for the applications requiring fast neutron measurements in the Indian Test Blanket Module (TBM) at the International Thermonuclear Experimental Reactor (ITER) Experiment. The detectors were characterized by leakage current measurements to ascertain that the leakage currents are low and breakdown voltages are higher than the voltage required for full charge collection. The detector response to charged particles was evaluated using a 238+239 Pu dual energy alpha source. The detectors showed an energy resolution of about 2% at 5.5 MeV. In order to study their suitability for the operation at higher temperatures, leakage current variation and alpha response were studied up to 300 °C. At 300 °C, peaks corresponding to 5.156 MeV and 5.499 MeV alphas could be separated and there was no significant degradation of energy resolution. Finally, the detector response to fast neutrons was evaluated using a Deuterium-Tritium (D-T) neutron generator. The observed spectrum showed peaks corresponding to various channels of n-C interactions with a clear isolated peak corresponding to 8.5 MeV alphas. The detectors also showed high sensitivity of 3.4×10-2 cps/n/(cm2 s)-4.5×10-2 cps/n/(cm2 s) and excellent linearity of response in terms of count rate at different neutron flux in the observed range of 3.2×105 n/(cm2 s) to 2.0×106 n/(cm2 s).

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

    NASA Astrophysics Data System (ADS)

    Cho, H.-M.; Ding, H.; Ziemer, BP; Molloi, S.

    2014-12-01

    Accurate energy calibration is critical for the application of energy-resolved photon-counting detectors in spectral imaging. The aim of this study is to investigate the feasibility of energy response calibration and characterization of a photon-counting detector using x-ray fluorescence. A comprehensive Monte Carlo simulation study was performed using Geant4 Application for Tomographic Emission (GATE) to investigate the optimal technique for x-ray fluorescence calibration. Simulations were conducted using a 100 kVp tungsten-anode spectra with 2.7 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3  ×  3 mm2 in detection area. The angular dependence of x-ray fluorescence and scatter background was investigated by varying the detection angle from 20° to 170° with respect to the beam direction. The effects of the detector material, shape, and size on the recorded x-ray fluorescence were investigated. The fluorescent material size effect was considered with and without the container for the fluorescent material. In order to provide validation for the simulation result, the angular dependence of x-ray fluorescence from five fluorescent materials was experimentally measured using a spectrometer. Finally, eleven of the fluorescent materials were used for energy calibration of a CZT-based photon-counting detector. The optimal detection angle was determined to be approximately at 120° with respect to the beam direction, which showed the highest fluorescence to scatter ratio (FSR) with a weak dependence on the fluorescent material size. The feasibility of x-ray fluorescence for energy calibration of photon-counting detectors in the diagnostic x-ray energy range was verified by successfully calibrating the energy response of a CZT-based photon-counting detector. The results of this study can be used as a guideline to implement the x-ray fluorescence calibration method for photon-counting detectors in a typical imaging laboratory.

  13. A study of the characteristics of scintillation detectors with a diffuse reflector

    NASA Astrophysics Data System (ADS)

    Baranov, V. A.; Filchenkov, V. V.; Konin, A. D.; Zhuk, V. V.

    1996-02-01

    The process of light collection in a scintillation counter with a diffuse reflector is studied using the Monte-Carlo codes "PHOTON" and "LIGHT". The results obtained are compared with the simple model estimations and employed to describe the time shape of the signal for several different detectors including the full absorption neutron spectrometer, and reanalyze the previous NE-213 transparency measurements.

  14. DETECTORS AND EXPERIMENTAL METHODS: Monte Carlo studies of micromegas as a neutron detector and its track reconstruction

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Zhang, Xiao-Dong; Wang, Wen-Xin; Yang, He-Run; Yang, Zheng-Cai; Hu, Bi-Tao

    2009-01-01

    In this paper a two dimensional readout micromegas detector with a polyethylene foil as converter was simulated on GEANT4 toolkit and GARFIELD for fast neutron detection. A new track reconstruction method based on time coincidence technology was developed in the simulation to obtain the incident neutron position. The results showed that with this reconstruction method higher spatial resolution was achieved.

  15. Preliminary study for the development of a tweezers-type coincidence detector for tumor detection

    NASA Astrophysics Data System (ADS)

    Yamamoto, Seiichi; Higashi, Tatsuya; Matsumoto, Keiichi; Senda, Michio

    2005-08-01

    We have conducted a preliminary study for development of a tweezer-type coincidence detector for tumor detection in procedures such as FDG-guided surgery. The detector consists of a pair of LSO scintillators, optical fibers, a pair of photo-multiplier tubes (PMTs), and a coincidence circuit. Because the LSO scintillators are located on the tips of tweezers, a target organ such as a lymph node or the colon can be positioned between them. The size of a single LSO was 3.7 mm×3.7 mm×10 mm, and the scintillation photons are transferred to the PMTs via 2-mm-diameter, 1-m long optical fibers. The results show that the light loss due to the fiber was significant but there was sufficient light to observe the photo-peak of the 511-keV gamma photons. Sensitivity response function perpendicular to the detector has a full-width at half-maximum (FWHM) of 2.5 mm, while that parallel to the detector has a FWHM of 5.5 mm. Background counts due to the natural radioisotope in 176Lu can be observed when the distance between these two scintillators is small. Results also show that the absolute sensitivity was 0.057% at the center of the detector when the two LSOs were 10 mm apart and that the optical fiber was insensitive to bending up to a radius of 10 cm. From these results, we conclude that the proposed tweezers-type coincidence detector could be some interest for tumor detection using FDG, such as that in radio-guided surgery.

  16. Study of laser location based on four-quadrant detector APD

    NASA Astrophysics Data System (ADS)

    Guo, Xing; Qian, Weixian; Gu, Guohua; Chen, Qian; Cao, Ercong; Hu, Xiaobo

    2016-10-01

    Laser positioning technology in the world has a very broad application prospects. With the development of technology and enhancement of productivity, the technology of positioning accuracy and the detection region also need to improve. There are key factors for laser positioning system, including performance of photosensitive devices, localization algorithm and signal processing circuitry, which are important in determining the performance advantages and disadvantages. Therefore, we need to study in-depth research and improvement to enhance the overall performance of the detector. In this paper, after analyzing the principle of mainstream photo-sensitive induction device, we focus on the current and various positioning algorithms which are widely used. Then use simulation to compare the advantages and disadvantages of each method. Based detector probe in the actual working conditions, we analyze the reasons for the differences in the measurement detector sensitivity, linearity, etc., and provide noise and uniformity correction algorithm while improving on the previous probe calibration method. According to the distribution of the incident light energy, we improve the mathematical model of the original description of the received light energy in each quadrant. Based on the Gaussian distribution of light energy, light intensity correction algorithm is proposed in order to meet the needs of the actual probe. Based on the selected four-quadrant detector APD, we design and build a complete laser positioning system. At last, we design and build the experimental system which can be used to test the main parameters including measurement accuracy and response range of the four-quadrant detector, so the laser positioning system has been tested and verify the feasibility of the system. This paper has mainly innovation in the localization algorithm on the detector.

  17. DETECTORS AND EXPERIMENTAL METHODS: Study on spatial resolution of micromegas as a neutron detector under condition of high neutron flux and γ ray background

    NASA Astrophysics Data System (ADS)

    Wang, Wen-Xin; Zhang, Yi; Wang, Ji-Jin; Hu, Bi-Tao

    2009-02-01

    In this paper Micromegas has been designed to detect neutrons. The simulation of the spatial resolution of Micromegas as neutron detector is carried out by GEANT4 toolkit. The neutron track reconstruction method based on the time coincidence technology is employed in the present work. The influence of the flux of incident 14 MeV neutron and high gamma background on the spatial resolution is carefully studied. Our results show that the spatial resolution of the detector is sensitive to the neutron flux, but insensitive to the intensity of γ background if the neutron track reconstruction method proposed by our group is used. The γ insensitivity makes it possible for us to use the Micromegas detector under condition which has high γ-rays background.

  18. A study of film and foil materials for the GEM detector proposed for the CMS muon system upgrade

    NASA Astrophysics Data System (ADS)

    Abbaneo, D.; Abbrescia, M.; Abi Akl, M.; Armaingaud, C.; Aspell, P.; Assran, Y.; Bally, S.; Ban, Y.; Banerjee, S.; Barria, P.; Benussi, L.; Bhopatkar, V.; Bianco, S.; Bos, J.; Bouhali, O.; Cai, J.; Calabria, C.; Caponero, M.; Castaneda, A.; Cauwenbergh, S.; Celik, A.; Christiansen, J.; Colafranceschi, S.; Colaleo, A.; Conde Garcia, A.; De Lentdecker, G.; De Oliveira, R.; de Robertis, G.; Dildick, S.; Ferrini, M.; Ferry, S.; Flanagan, W.; Franchi, A. V.; Gilmore, J.; Gutierrez, A.; Hoepfner, K.; Hohlmann, M.; Kamon, T.; Karchin, P. E.; Khotilovich, V.; Krutelyov, S.; Loddo, F.; Maerschalk, T.; Magazzu, G.; Maggi, M.; Maghrbi, Y.; Marchioro, A.; Marinov, A.; Majumdar, N.; Merlin, J. A.; Mukhopadhyay, S.; Nuzzo, S.; Oliveri, E.; Passamonti, L.; Philipps, B.; Piccolo, D.; Pierluigi, D.; Postema, H.; Radi, A.; Radogna, R.; Raffone, G.; Ranieri, A.; Rodrigues, A.; Ropelewski, L.; Russo, A.; Safonov, A.; Sakharov, A.; Salva, S.; Saviano, G.; Sharma, A.; Tatarinov, A.; Teng, H.; Turini, N.; Twigger, J.; Tytgat, M.; van Stenis, M.; Verhagen, E.; Valente, M.; Yang, Y.; Zaganidis, N.; Zenoni, F.

    2014-04-01

    During the next shutdown of the LHC at CERN, the CMS experiment plans to start installing GEM detectors in the endcap (high pseudorapidity) region. These muon detectors have excellent spatial and temporal resolution as well as a high chemical stability and radiation hardness. A report is given on preliminary results of materials studies that aimed to fully characterize the GEM detector components before and after the exposure to a high-radiation environment.

  19. The MICROMEGEM detector

    NASA Astrophysics Data System (ADS)

    Bouhali, O.; De Lentdecker, G.; Dewèze, S.; Udo, F.; Van Doninck, W.; Vander Velde, C.; Van Lancker, L.; Zhukov, V.; Boulogne, I.; Daubie, E.

    2001-02-01

    This article introduces the MICROMEGEM detector, a position-sensitive proportional gas counter produced using advanced Printed Circuit Board (PCB) technology. The detector is equipped with a Gas Electron Multiplier (GEM) foil placed 50 μm above a plane of pick-up strips. The GEM produces a first gas amplification which is extended below the GEM foil by applying a strong electric field between the strips and the lower electrode of the GEM. The array of strips is used for read-out to obtain 1-D positional information. We present results on the gas gain, the energy resolution and the rate capability. The behaviour in an intense beam of 300 MeV/c pions in presence of heavily ionizing particles has also been investigated.

  20. Photoluminescence Study of Long Wavelength Superlattice Infrared Detectors

    NASA Technical Reports Server (NTRS)

    Hoglund, Linda; Khoshakhlagh, Arezou; Soibel, Alexander; Ting, David Z.; Hill, Cory J.; Keo, Sam; Gunapala, Sarath D.

    2011-01-01

    In this paper, the relation between the photoluminescence (PL) intensity and the PL peak wavelength was studied. A linear decrease of the PL intensity with increasing cut-off wavelength of long wavelength infrared CBIRDs was observed at 77 K and the trend remained unchanged in the temperature range 10 - 77 K. This relation between the PL intensity and the peak wavelength can be favorably used for comparison of the optical quality of samples with different PL peak wavelengths. A strong increase of the width of the PL spectrum in the studied temperature interval was observed, which was attributed to thermal broadening.

  1. Study on the mechanism of a charge-coupled device detector irradiated by millisecond pulse laser under functional loss.

    PubMed

    Li, Mingxin; Jin, Guangyong; Tan, Yong; Guo, Ming; Zhu, Pengbo

    2016-02-20

    The damage mechanism of a CCD detector was studied by building an experimental system containing a millisecond pulse laser irradiating a CCD detector. The experimental results show that the damage on the CCD detector was mainly thermal damage, along with mechanical damage. A melting phenomenon was caused by the thermal damage, so that a crater was observed on the surface of the CCD detector. Caused by melting of the polysilicon electrodes and a temperature rise in the silicon dioxide, the shift register impedance values were sharply reduced. Most of the substrate clock signals were broken and disappeared due to melting of channels in the silicon substrate layer, which caused a functional loss for the CCD detector. The mechanical damage on the melting edge of the CCD detector created heave; the temperature gradient caused this damage. In this paper, the decrease in vertical shift register impedance values was consistent with previous test results.

  2. Studies of Nuclear Structure using Radioactive Decay and a Large Array of Compton Suppressed Ge Detectors

    NASA Astrophysics Data System (ADS)

    Wood, John L.

    2000-11-01

    Radioactive decay has long played a role in contributing to the elucidation of nuclear structure. However compared to in-beam gamma-ray spectroscopy, which has been combined with the extraordinary power of multi-detector arrays, radioactive decay scheme studies have been carried out usually with rather modest detector set-ups (two detectors, no Compton suppression). An extensive program to rectify this situation has been initiated using the "8-PI spectrometer"[1]. This is an array of 20 Compton-suppressed Ge detectors with exceptional stability and peak-to-total ratio. Experiments performed[2] recently at Lawrence Berkeley Laboratory, to better characterize nuclear deformation properties and the onset of deformation in nuclei, will be described. Future plans for the study of nuclei far from beta stability at the TRIUMF/ISAC Facility using the 8-PI spectrometer will also be outlined. [1] J.P.Martin et al., Nucl.Instr.Meth. A 257, 301 (1987). [2] See, e.g., W.D.Kulp et al. Bull.Am.Phys.Soc. 44, 63 (1999); W.D.Kulp et al., ibid., Williamsburg Meeting, Oct 4-7 (2000).

  3. Performance study of the new light collection system for the ICARUS T600 detector

    NASA Astrophysics Data System (ADS)

    Falcone, A.; ICARUS Collaboration

    2017-09-01

    The ICARUS T600 detector is the largest liquid argon time projection chamber (LArTPC) to be built and operated [1]. This detector was in operation in the INFN Gran Sasso underground laboratory until 2012, exposed to the CERN Neutrino to Gran Sasso (CNGS) νµ beam, performing neutrino oscillation studies. The ICARUS T600 is presently under refurbishment in order to make it suitable for surface level operation, as it will serve as the far detector for the Short-Baseline Neutrino (SBN) Program at Fermilab [2]. A major upgrade of the ICARUS detector in order to allow it to cope with a high cosmic background is the upgrade of the light collection system. The study presented here shows a simulation to optimize the PMT layout to allow for the localization and identification of interaction within the T600. An excellent performance can be obtained, with an error on the localization smaller than 20 cm and of the order of a few percent in the identification of cosmic rays.

  4. Study of a Li doped CsI scintillator crystal as a neutron detector

    NASA Astrophysics Data System (ADS)

    Madi Filho, T.; Pereira, M. C. C.; Berretta, J. R.; Cárdenas, J. P. N.

    2015-07-01

    The radiation monitoring system is an important requirement in the premises of a nuclear reactor. A variety of types of radiation (neutrons. gamma. beta and fission products) exist in a reactor. associated to the broad energy spectrum of these radiations. implying the need of detectors to be used in the reactor system and security. as well as radiation monitoring. As the neutron sources are associated to gamma radiation. it is necessary that the neutron detecting system may be capable to discriminate the gamma interference. In our work environment. there are two Nuclear Research Reactors and a neutron irradiator with two AmBe sources (592GBq of Am. each). These conditions warrant the development of new types of detectors. Due to the absence of charge in the neutron. it is necessary to use a converter material that generates radiations capable to produce signals in the detector. Materials with high cross section. like Li or B. are used for this purpose. The CsIcrystal doped with 6Li has been studied. The concentration of the lithium doping element (Li) studied was 10-3M. The detector test was done using an AmBe source (37GBq) and gamma sources. The crystal was coupled to a photomultiplier.

  5. A Study of a GEM Tracking Detector for Imaging Positrons from PET Radioisotopes in Plants

    NASA Astrophysics Data System (ADS)

    Cao, T.; Azmoun, B.; Babst, B.; Blatnik, M.; Purschke, M. L.; Stoll, S.; Vaska, P.; Woody, C.

    2014-10-01

    Positron Emission Tomography is a powerful imaging technique used for humans and animals that can also be used to study plant biology. However, since many of the structures found on plants (e.g., leaves) are very thin, a large portion of the positrons emitted from PET isotopes escape before annihilation, leading to low efficiency and quantification inaccuracies. In this study, a gas tracking detector was used to measure escaping positrons from PET radiotracer isotopes which has the ability to reconstruct three dimensional tracks that can be used to form an image of the emitting object. This device uses a triple GEM detector with a short drift region and an XY strip readout plane to measure a vector for positrons passing through a drift gap. By projecting each particle track back to the object surface, a 2-D image of the spatial distribution of the positrons that escaped from that surface can be reconstructed. In this paper, we will describe the basic principle of the GEM detector and present results on its performance using various types of phantoms and actual plant specimens. Monte Carlo simulations are also used to better understand the detector performance and compare to actual measurements.

  6. Using induced signals to sense position from a microchannel plate detector

    NASA Astrophysics Data System (ADS)

    deSouza, R. T.; Gosser, Z. Q.; Hudan, S.

    2012-05-01

    We demonstrate a novel concept for a position sensitive microchannel plate detector. This detector provides sub-millimeter spatial resolution by examining the signal induced on a wire harp by the electron cloud from a microchannel plate detector. Wires in the harp are efficiently read out by coupling them to a delay line.

  7. Ultra-thin plasma radiation detector

    DOEpatents

    Friedman, Peter S.

    2017-01-24

    A position-sensitive ionizing-radiation counting detector includes a radiation detector gas chamber having at least one ultra-thin chamber window and an ultra-thin first substrate contained within the gas chamber. The detector further includes a second substrate generally parallel to and coupled to the first substrate and defining a gas gap between the first substrate and the second substrate. The detector further includes a discharge gas between the substrates and contained within the gas chamber, where the discharge gas is free to circulate within the gas chamber and between the first and second substrates at a given gas pressure. The detector further includes a first electrode coupled to one of the substrates and a second electrode electrically coupled to the first electrode. The detector further includes a first discharge event detector coupled to at least one of the electrodes for detecting a gas discharge counting event in the electrode.

  8. Advanced far infrared detector and double donor studies in Ge

    SciTech Connect

    Olsen, Christopher Sean

    1994-12-01

    This has application to astronomy and astrophysics. Selenium in Ge has been studied with a doping technique which limits complex formation. Only one ionization level has been found to correspond to selenium, which presumably occupies a substitutional site. This level is extremely unstable and its concentration decreases after annealing at 400C. Future work is planned to anneal the fast neutron damage before much selenium has formed in the {sup 74/76}Ge samples. It is expected that the observed selenium level can be better characterized and the missing selenium level is more likely to be discovered if other defects are removed before {sup 77}Se formation.

  9. Study directed at development of an implantable biotelemetry ion detector

    NASA Technical Reports Server (NTRS)

    Hanley, L. D.; Kress, D.

    1971-01-01

    A literature search was conducted to currently update known information in the field of ion-selective electrodes. The review attempts to identify present trends in cation and anions selective electrodes pertinent to the area of bioimplantable units. An electronic circuit was designed to provide the high impedance interface between the ion-selective sensors and signal-processing equipment. The resulting design emphasized the need for low power and miniaturization. Many of the circuits were constructed and used to evaluate the ion-selective electrodes. A cuvette capable of holding the ion-selective and the reference electrodes was designed and constructed. This equipment was used to evaluate commercially available ion-selective electrodes and the electrodes designed and constructed in the study. The results of the electrode tests are included.

  10. Etching characteristic studies for the detection of alpha particles in DAM-ADC nuclear track detector

    NASA Astrophysics Data System (ADS)

    El-Samman, H.; Ashry, A. H.; Arafa, W.; Abou-leila, M.; Abdalla, A. M.; Tsuruta, T.

    2014-09-01

    This study reports the characteristic studies for the detection of alpha particles in DAM-ADC nuclear track detector. Several important parameters that control the track formation such as, the bulk etch rate (VB), track etching rate (VT), dependence of VB and VT on etching concentration and temperature have been extensively studied. The activation energy (Eb) of the bulk etching rate for the DAM-ADC sheets has been calculated, the dependence of etching efficiency and sensitivity upon etchant concentrations and temperature has been investigated, registration efficiency of DAM-ADC detector etched at the optimum etching condition has been examined. The detailed studied results presented in this study provide various useful information about the mechanism of track formation in polymers.

  11. FEASIBILITY STUDY FOR THE DEVELOPMENT OF A TEST BED PROGRAM FOR NOVEL DETECTORS AND DETECTOR MATERIALS AT SRS H-CANYON SEPARATIONS FACILITY

    SciTech Connect

    Sexton, L.; Mendez-Torres, A.; Hanks, D.

    2011-06-07

    Researchers at the Savannah River National Laboratory (SRNL) have proposed that a test bed for advanced detectors be established at the H-Canyon separations facility located on the DOE Savannah River Site. The purpose of the proposed test bed will be to demonstrate the capabilities of emerging technologies for national and international safeguards applications in an operational environment, and to assess the ability of proven technologies to fill any existing gaps. The need for such a test bed has been expressed in the National Nuclear Security Administration's (NNSA) Next Generation Safeguards Initiative (NGSI) program plan and would serve as a means to facilitate transfer of safeguards technologies from the laboratory to an operational environment. New detectors and detector materials open the possibility of operating in a more efficient and cost effective manner, thereby strengthening national and international safeguards objectives. In particular, such detectors could serve the DOE and IAEA in improving timeliness of detection, minimizing uncertainty and improving confidence in results. SRNL's concept for the H Canyon test bed program would eventually open the facility to other DOE National Laboratories and establish a program for testing national and international safeguards related equipment. The initial phase of the test bed program is to conduct a comprehensive feasibility study to determine the benefits and challenges associated with establishing such a test bed. The feasibility study will address issues related to the planning, execution, and operation of the test bed program. Results from the feasibility study will be summarized and discussed in this paper.

  12. Study of a high-resolution, 3-D positioning cadmium zinc telluride detector for PET

    PubMed Central

    Gu, Y; Matteson, J L; Skelton, R T; Deal, A C; Stephan, E A; Duttweiler, F; Gasaway, T M; Levin, C S

    2011-01-01

    This paper investigates the performance of 1 mm resolution Cadmium Zinc Telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3-D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06±0.39% at 511 keV throughout most the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44±0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78±0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes – as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system. PMID:21335649

  13. Multilayer Scintillator Responses for Mo Observatory of Neutrino Experiment Studied Using a Prototype Detector MOON-1

    NASA Astrophysics Data System (ADS)

    Nakamura, Hidehito; Doe, Peter J.; Ejiri, Hiroyasu; Elliott, Steven R.; Engel, Jonathan; Finger, Miroslav; Finger,, Michael; Fushimi, Kenichi; Gehman, Victor M.; Greenfield, Mark B.; Hai, Vo H.; Hazama, Ryuta; Imaseki, Hitoshi; Kavitov, Petr; Kekelidze, Vladimir D.; Kitamura, Hisashi; Matsuoka, Kenji; Nomachi, Masaharu; Ogama, Takeo; Para, Adam; Robertson, R. G. Hamish; Sakiuchi, Takuya; Shima, Tatsushi; Slunecka, Milos; Shirkov, Grigori D.; Sissakian, Alexei N.; Titov, Alexander I.; Uchihori, Yukio; Umehara, Saori; Urano, Atsushi; Vaturin, Vladimir; Voronov, Victor V.; Wilkerson, John F.; Will, Douglas I.; Yasuda, Kensuke; Yoshida, Sei

    2007-11-01

    An ensemble of multilayer scintillators is discussed as an option of the high-sensitivity detector MOON (Mo Observatory of Neutrinos) for spectroscopic measurements of neutrinoless double beta decays. A prototype detector MOON-1, which consists of 6-layer plastic scintillator plates, was built to study the photon responses of the MOON-type detector. The photon responses, i.e., the number of scintillation photons collected and the energy resolution, which are key elements for high-sensitivity experiments, are found to be 1835± 30 photoelectrons for 976 keV electrons and σ=2.9± 0.1% (Δ E/E=6.8± 0.3% in FWHM) at the Qββ˜ 3 MeV region, respectively. The multilayer plastic scintillator structure with high energy resolution as well as a good signal for the background suppression of β-γ rays is crucial for the MOON-type detector to achieve inverted-hierarchy neutrino-mass sensitivity. It will also be useful for medical and other rare-decay experiments as well.

  14. An experimental study of antireflective coatings in Ge light detectors for scintillating bolometers

    NASA Astrophysics Data System (ADS)

    Mancuso, M.; Beeman, J. W.; Giuliani, A.; Dumoulin, L.; Olivieri, E.; Pessina, G.; Plantevin, O.; Rusconi, C.; Tenconi, M.

    2014-01-01

    Luminescent bolometers are double-readout devices able to measure simultaneously the phonon and the light yields after a particle interaction in the detector. This operation allows in some cases to tag the type of the interacting quantum, crucial issue for background control in rare event experiments such as the search for neutrinoless double beta decay and for interactions of particle dark matter candidates. The light detectors used in the LUCIFER and LUMINEU searches (projects aiming at the study of the double beta interesting candidates 82Se and 100Mo using ZnSe and ZnMoO4 scintillating bolometers) consist of hyper-pure Ge thin slabs equipped with NTD thermistors. A substantial sensitivity improvement of the Ge light detectors can be obtained applying a proper anti-reflective coatings on the Ge side exposed to the luminescent bolometer. The present paper deals with the investigation of this aspect, proving and quantifying the positive effect of a SiO2 and a SiO coating and setting the experimental bases for future tests of other coating materials. The results confirm that an appropriate coating procedure helps in improving the sensitivity of bolometric light detectors by an important factor (in the range 20% - 35%) and needs to be included in the recipe for the development of an optimized radio-pure scintillating bolometer.

  15. Study of muons near shower cores at sea level using the E594 neutrino detector

    NASA Technical Reports Server (NTRS)

    Goodman, J. A.; Gupta, S. C.; Freudenreich, H.; Sivaprasad, K.; Tonwar, S. C.; Yodh, G. B.; Ellsworth, R. W.; Goodman, M. C.; Bogert, D.; Burnstein, R.

    1985-01-01

    The E594 neutrino detector has been used to study the lateral distribution of muons of energy 3 GeV near shower cores. The detector consists of a 340 ton fine grain calorimeter with 400,000 cells of flash chamber and dimensions of 3.7 m x 20 m x 3.7 m (height). The average density in the calorimeter is 1.4 gm/sq cm, and the average Z is 21. The detector was triggered by four 0.6 sq m scintillators placed immediately on the top of the calorimeter. The trigger required at least two of these four counters. The accompanying extensive air showers (EAS) was sampled by 14 scintillation counters located up to 15 m from the calorimeter. Several off line cuts have been applied to the data. Demanding five particles in at least two of the trigger detectors, a total of 20 particles in all of them together, and an arrival angle for the shower 450 deg reduced the data sample to 11053 events. Of these in 4869 cases, a computer algorithm found at least three muons in the calorimeter.

  16. Digital X-ray imaging using silicon microstrip detectors: a design study

    NASA Astrophysics Data System (ADS)

    Speller, R. D.; Royle, G. J.; Triantis, F. A.; Manthos, N.; Van der Stelt, P. F.; di Valentin, M.

    2001-01-01

    This paper considers the basic design parameters for using silicon microstrip detectors for 2-D medical imaging. In particular, mammographic and dental imaging are considered. Monte Carlo modeling techniques have been used to investigate detector efficiency, strip pitch, image quality, imaging geometry and signal processing requirements. Different phantoms are used for each part of the study. It is shown that signal processing times are a major factor in the operation of a clinical detector system if ambiguities are to be avoided in a double-sided strip detector. However, the use of the models allows conclusions to be made that alleviate the timing requirements. It has been shown that using a strip structure of 50-100 μm provides appropriate image resolution and image quality can be maintained with pixel counts of 50-100 in both dental and mammographic work. Under these conditions current front-end electronics designs can provide the signal processing times with an acceptably small number of multihit events (<5%).

  17. Time of flight experimental studies of CdZnTe radiation detectors

    NASA Astrophysics Data System (ADS)

    Erickson, J. C.; Yao, H. W.; James, R. B.; Hermon, H.; Greaves, M.

    2000-06-01

    A time of flight technique was used to study the carrier trapping time, τ, and mobility, μ, in CdZnTe (CZT) and CdTe radiation detectors. Carriers were generated near the surface of the detector by a nitrogen-pumped pulsed dye laser with wavelength ˜500 nm. Signals from generated electrons or holes were measured by a fast oscilloscope and analyzed to determine the trapping time and mobility of carriers. Electron mobility was observed to change with temperature from 1200 cm2/Vs to 2400 cm2/Vs between 293 K and 138 K, respectively. Electron mobilities were observed between 900 cm2/Vs and 1350 cm2/Vs at room temperature for various CZT detectors. Electron mobilities in various CdTe detectors at room temperature were observed between 740 cm2/Vs and 1260 cm2/Vs. Average electron mobility was calculated to be 1120 cm2/Vs and 945 cm2/Vs for CZT and CdTe, respectively. Hole mobilities in both CZT and CdTe were found to vary between 27 cm2/Vs and 66 cm2/Vs. Electron trapping times in CZT at room temperature varied from 1.60 µs to 4.18 µs with an average value of about 2.5 µs. Electron trapping time in CdTe at room temperature varied between 1.7 µs and 4.15 µs with an average value of about 3.1 µs.

  18. A Geant Study of the Scintillating Optical Fiber (SOFCAL) Cosmic Ray Detector

    NASA Technical Reports Server (NTRS)

    Munroe, Ray B., Jr.

    1998-01-01

    Recent energy measurements by balloon-borne passive emulsion chambers indicate that the flux ratios of protons to helium nuclei and of protons to all heavy nuclei decrease as the primary cosmic ray energy per nucleon increases above approx. 200 GeV/n, and suggest a "break" in the proton spectrum between 200 GeV and 5 TeV. However, these passive emulsion chambers are limited to a lower energy threshold of approx. 5 TeV/n, and cannot fully explore this energy regime. Because cosmic ray flux and composition details may be significant to acceleration models, a hybrid detector system called the Scintillating Optical Fiber Calorimeter (SOFCAL) has been designed and flown. SOFCAL incorporates both conventional passive emulsion chambers and an active calorimeter utilizing scintillating plastic fibers as detectors. These complementary types of detectors allow the balloon-borne SOFCAL experiment to measure the proton and helium spectra from approx. 400 GeV/n to approx. 20 TeV. The fundamental purpose of this study is to use the GEANT simulation package to model the hadronic and electromagnetic shower evolution of cosmic rays incident on the SOFCAL detector. This allows the interpretation of SOFCAL data in terms of charges and primary energies of cosmic rays, thus allowing the determinations of cosmic ray flux and composition as functions of primary energy.

  19. Study of a high-resolution, 3D positioning cadmium zinc telluride detector for PET

    NASA Astrophysics Data System (ADS)

    Gu, Y.; Matteson, J. L.; Skelton, R. T.; Deal, A. C.; Stephan, E. A.; Duttweiler, F.; Gasaway, T. M.; Levin, C. S.

    2011-03-01

    This paper investigates the performance of 1 mm resolution cadmium zinc telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06 ± 0.39% at 511 keV throughout most of the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44 ± 0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78 ± 0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes—as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system.

  20. Study of a high-resolution, 3D positioning cadmium zinc telluride detector for PET.

    PubMed

    Gu, Y; Matteson, J L; Skelton, R T; Deal, A C; Stephan, E A; Duttweiler, F; Gasaway, T M; Levin, C S

    2011-03-21

    This paper investigates the performance of 1 mm resolution cadmium zinc telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06 ± 0.39% at 511 keV throughout most of the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44 ± 0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78 ± 0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes-as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system.

  1. Study of light transport inside scintillation crystals for PET detectors.

    PubMed

    Yang, Xin; Downie, Evan; Farrell, Thomas; Peng, Hao

    2013-04-07

    Scintillation crystal design is a critical component in positron emission tomography system development, which impacts a number of performance parameters including energy resolution, time resolution and spatial resolution. Our work aims to develop a generalized simulation tool to model the light transport inside scintillation crystals with good accuracy, taking into account surface treatments, reflectors, temporal dependence of scintillation decay, and comprehensive experimental validations. The simulation has been validated against both direct analytical calculation and experimental measurements. In this work, the studies were performed for a lutetium-yttrium oxyorthosilicate crystal of 3×3×20 mm(3) dimension coupled to a Hamamatsu silicon photomultiplier, with respect to light output, rise-time slope, energy resolution and time resolution. Four crystal surface treatment and reflector configurations were investigated: GroundMetal, GroundPaint, PolishMetal and PolishPaint. The experiments were performed to validate the Monte Carlo simulation results. The results indicate that the best time resolution (0.96±0.05 ns) and good energy resolution (10.6±0.4%) could be produced by using a polished surface with specular reflector, while the configuration of a polished surface with diffusive reflector produces the best energy resolution (10.2±0.9%). The results indicate that a polished surface with diffusive reflector achieves the best energy resolution (10.2±0.9%) for 511 keV high energy photons, and a polished surface with specular reflector achieves the best time resolution (0.96±0.05 ns) measured against a Hamamatsu fast photomultiplier tube. The ground surface treatment is not recommended for its inferior performance in terms of energy and time resolution. Possible explanations and future improvements to be made to the developed simulation tool are discussed.

  2. Study of indium and solder bumps for the BTeV Pixel Detector

    SciTech Connect

    Simon W Kwan et al.

    2003-11-05

    The pixel detector proposed for the BTeV experiment at the Fermilab Tevatron will use bump-bonding technology based on either Indium or Pb/Sn solder to connect the front-end readout chips to the silicon pixel sensors. We have studied the strength of the bumps by visual inspection of the bumps bonding silicon sensor modules to dummy chips made out of glass. The studies were done before and after thermal cycles, exposed to intense irradiation, and with the assemblies glued to a graphite substrate. We have also carried out studies on effects of temperature changes on both types of bump bonds by observing the responses of single-chip pixel detectors to an Sr{sup 90} source. We report the results from these studies and our plan to measure the effect of cryogenic temperatures on the bumps.

  3. DETECTORS AND EXPERIMENTAL METHODS Design and simulations for the detector based on DSSSD

    NASA Astrophysics Data System (ADS)

    Xu, Yan-Bing; Wang, Huan-Yu; Meng, Xiang-Cheng; Wang, Hui; Lu, Hong; Ma, Yu-Qian; Li, Xin-Qiao; Shi, Feng; Wang, Ping; Zhao, Xiao-Yun; Wu, Feng

    2010-12-01

    The present paper describes the design and simulation results of a position-sensitive charged particle detector based on the Double Sided Silicon Strip Detector (DSSSD). Also, the characteristics of the DSSSD and its testing result were are discussed. With the application of the DSSSD, the position-sensitive charged particle detector can not only give particle flux and energy spectra information and identify different types of charged particles, but also measure the location and angle of incident particles. As the detector can make multiparameter measurements of charged particles, it is widely used in space detection and exploration missions, such as charged particle detection related to earthquakes, space environment monitoring and solar activity inspection.

  4. Study of Electromagnetic Interactions with the MicroBooNE Detector

    NASA Astrophysics Data System (ADS)

    Caratelli, David; MicroBooNE Collaboration

    2017-01-01

    MicroBooNE is an experiment which employs the Liquid Argon Time Projection Chamber (LArTPC) detector technology to study neutrinos produced with the Fermilab Booster Neutrino Beam. As for any accelerator-based detector interested in studying neutrino oscillations, it is essential to be able to identify and reconstruct the kinematic properties of electrons and photons produced in μν and νe interactions. We report current progress in reconstructing electron and photon electromagnetic (EM) showers using data from the MicroBooNE LArTPC. These studies cover EM showers in the tens to hundreds of MeV energy range; they lay the foundation for MicroBooNE's investigation of the excess of low-energy EM events reported by MiniBooNE, and are of interest to the wider LArTPC neutrino community.

  5. Magnetic field influences on the lateral dose response functions of photon-beam detectors: MC study of wall-less water-filled detectors with various densities

    NASA Astrophysics Data System (ADS)

    Khee Looe, Hui; Delfs, Björn; Poppinga, Daniela; Harder, Dietrich; Poppe, Björn

    2017-06-01

    The distortion of detector reading profiles across photon beams in the presence of magnetic fields is a developing subject of clinical photon-beam dosimetry. The underlying modification by the Lorentz force of a detector’s lateral dose response function—the convolution kernel transforming the true cross-beam dose profile in water into the detector reading profile—is here studied for the first time. The three basic convolution kernels, the photon fluence response function, the dose deposition kernel, and the lateral dose response function, of wall-less cylindrical detectors filled with water of low, normal and enhanced density are shown by Monte Carlo simulation to be distorted in the prevailing direction of the Lorentz force. The asymmetric shape changes of these convolution kernels in a water medium and in magnetic fields of up to 1.5 T are confined to the lower millimetre range, and they depend on the photon beam quality, the magnetic flux density and the detector’s density. The impact of this distortion on detector reading profiles is demonstrated using a narrow photon beam profile. For clinical applications it appears as favourable that the magnetic flux density dependent distortion of the lateral dose response function, as far as secondary electron transport is concerned, vanishes in the case of water-equivalent detectors of normal water density. By means of secondary electron history backtracing, the spatial distribution of the photon interactions giving rise either directly to secondary electrons or to scattered photons further downstream producing secondary electrons which contribute to the detector’s signal, and their lateral shift due to the Lorentz force is elucidated. Electron history backtracing also serves to illustrate the correct treatment of the influences of the Lorentz force in the EGSnrc Monte Carlo code applied in this study.

  6. Physics Studies for the CMS muon system upgrade with triple-GEM detectors

    NASA Astrophysics Data System (ADS)

    Caputo, C.

    2014-12-01

    The CMS collaboration considers upgrading the muon forward region with Gas Electron Multiplier (GEM) chambers, which are able to handle the extreme particle rates expected in this region along with a high spatial resolution. This allows to combine tracking and triggering capabilities, resulting in a lower trigger threshold along with improved muon identification and track reconstruction. In the last year the GEM project took a major leap forward by integrating triple-GEM chambers in the official CMS software, allowing physics studies to be carried out. Several benchmark analyses have been studied for the impact of such detector upgrade on the physics performance. In this contribution the status of the CMS upgrade project with the usage of GEM detector will be reviewed, discussing the trigger, the muon reconstruction performance, and the impact on the physics analyses.

  7. [Study on spectra pretreatment in near infrared spectroscopy analysis using charger coupled device detector].

    PubMed

    Xu, G; Yuan, H; Lu, W

    2000-10-01

    The effects of spectra pretreatment method and parameters to signal noise ratio and calibration models quality in near-infrared spectroscopy analysis using charger coupled device(CCD) detector have been studied and discussed. To attain higher signal noise ratio, in the range of 700-1,100 nm, using 2048 pixels CCD, we suggest that the optimal gaps of smoothing first derivative treatment of spectra are 9 points, and the gap of second derivative treatment is 19 points.

  8. Dosimetric study of thermoluminescent detectors in clinical photon beams using liquid water and PMMA phantoms.

    PubMed

    Matsushima, Luciana C; Veneziani, Glauco R; Sakuraba, Roberto K; da Cruz, José C; Campos, Letícia L

    2012-07-01

    The purpose of this study was the dosimetric evaluation of thermoluminescent detectors of calcium sulphate doped with dysprosium (CaSO4:Dy) produced by IPEN compared to the TL response of lithium fluoride doped with magnesium and titanium (LiF:Mg,Ti) dosimeters and microdosimeters produced by Harshaw Chemical Company to clinical photon beams dosimetry (6 and 15 MV) using liquid water and PMMA phantoms.

  9. Study of timing response and charge spectra of glass based Resistive Plate Chamber detectors for INO-ICAL experiment

    NASA Astrophysics Data System (ADS)

    Gaur, A.; Kumar, A.; Naimuddin, Md.

    2017-03-01

    Resistive Plate chambers (RPCs) are robust and affordable gaseous detectors that combine low cost with excellent timing, good spatial resolution and fast response to the incoming particles. The India Based Neutrino Observatory is an approved project aimed at building a magnetised Iron Calorimeter (ICAL) detector to study Neutrino physics and related issues. The ICAL experiment will utilize about 29000 RPC's as active detector elements, sandwiched between alternate plates of thick iron. The RPC detectors will be used to detect muons produced from the atmospheric neutrinos interaction with an iron target. The spatial information of the muons will be extracted from the two dimensional readout and the hit position in the respective layers. The up going and down going directionality will be obtained using the time stamp of hits in the active detectors. The charge induced by the particle and its behaviour with respect to the applied voltage play a significant role in designing the readout electronics for the detector. In this paper, we present the timing and charge measurement of single gap glass based RPC detectors. We will also report about studies on the dependence of the timing and charge response of these RPC detectors as a function of the gas composition.

  10. Classification of soil magnetic susceptibility and prediction of metal detector performance: case study of Angola

    NASA Astrophysics Data System (ADS)

    Preetz, Holger; Altfelder, Sven; Hennings, Volker; Igel, Jan

    2009-05-01

    Soil magnetic properties can seriously impede the performance of metal detectors used in landmine clearance operations. For a proper planning of clearance operations pre-existing information on soil magnetic susceptibility can be helpful. In this study we briefly introduce a classification system to assess soil magnetic susceptibilities from geoscientific maps. The classification system is based on susceptibility measurements conducted on archived lateritic soil samples from 15 tropical countries. The system is applied to a soil map of Angola, resulting in a map that depicts soil magnetic susceptibilities as a worst case scenario. An additional layer depicting the surveyed mine affected communities in Angola is added to the map, which demonstrates that a large number of those are located in areas where soil is expected to impede metal detector performance severely.

  11. Study of a sealed high gas pressure THGEM detector and response of alpha particle spectra

    NASA Astrophysics Data System (ADS)

    Zhang, Yu-Ning; Liu, Qian; Liu, Hong-Bang; Xie, Yi-Gang; Lyu, Xiao-Rui; Chen, Shi; Huang, Wen-Qian; Hong, Dao-Jin; Zheng, Yang-Heng

    2017-04-01

    A sealed high gas pressure detector working in pure argon is assembled. It consists of a 5 cm × 5 cm PCB THGEM (THick Gaseous Electron Multiplier). The detector structure and experimental setup are described. The performance under high pressure (2 atm) is examined, selecting optimal voltages for the ionization region and induction region. The dependence of the shape of alpha particle spectra measured with relative gas gain on gas pressure (1.3-2.0 atm) has been studied. Eight data sets of relative gas gain versus working voltage of THGEM, expressed by weighting field E/P, are normalized, consistent with theory. The results show that the air tightness of the chamber is good, measured by a sensitive barometer and checked with gas gain. The experimental results are compared with Monte Carlo simulation of energy deposition without gas gain involved. Supported by National Natural Science Foundation of China (11575193, 11205240, 11265003, U1431109)

  12. Study of imaging plate detector sensitivity to 5-18 MeV electrons

    SciTech Connect

    Boutoux, G. Rabhi, N.; Batani, D.; Ducret, J.-E.; Binet, A.; Nègre, J.-P.; Reverdin, C.; Thfoin, I.; Jakubowska, K.

    2015-11-15

    Imaging plates (IPs) are commonly used as passive detectors in laser-plasma experiments. We calibrated at the ELSA electron beam facility (CEA DIF) the five different available types of IPs (namely, MS-SR-TR-MP-ND) to electrons from 5 to 18 MeV. In the context of diagnostic development for the PETawatt Aquitaine Laser (PETAL), we investigated the use of stacks of IP in order to increase the detection efficiency and get detection response independent from the neighboring materials such as X-ray shielding and detector supports. We also measured fading functions in the time range from a few minutes up to a few days. Finally, our results are systematically compared to GEANT4 simulations in order to provide a complete study of the IP response to electrons over the energy range relevant for PETAL experiments.

  13. β-Decay Studies of r-Process Nuclei Using the Advanced Implantation Detector Array (AIDA)

    NASA Astrophysics Data System (ADS)

    Griffin, C. J.; Davinson, T.; Estrade, A.; Braga, D.; Burrows, I.; Coleman-Smith, P. J.; Grahn, T.; Grant, A.; Harkness-Brennan, L. J.; Kiss, G.; Kogimtzis, M.; Lazarus, I. H.; Letts, S. C.; Liu, Z.; Lorusso, G.; Matsui, K.; Nishimura, S.; Page, R. D.; Prydderch, M.; Phong, V. H.; Pucknell, V. F. E.; Rinta-Antila, S.; Roberts, O. J.; Seddon, D. A.; Simpson, J.; Thomas, S. L.; Woods, P. J.

    Thought to produce around half of all isotopes heavier than iron, the r-process is a key mechanism for nucleosynthesis. However, a complete description of the r-process is still lacking and many unknowns remain. Experimental determination of β-decay half-lives and β-delayed neutron emission probabilities along the r-process path would help to facilitate a greater understanding of this process. The Advanced Implantation Detector Array (AIDA) represents the latest generation of silicon implantation detectors for β-decay studies with fast radioactive ion beams. Preliminary results from commissioning experiments demonstrate successful operation of AIDA and analysis of the data obtained during the first official AIDA experiments is now under-way.

  14. A study of radon and thoron release from Egyptian building materials using polymeric nuclear track detectors.

    PubMed

    Hafez, A F; Hussein, A S; Rasheed, N M

    2001-02-01

    The free exhalation rates of both thoron and radon, the specific activities of 224Ra, and 226Ra, and the physical properties, such as the emanation coefficients and radon effective diffusion coefficient of several building material samples were determined using LR-115 and CR-39 polymeric nuclear track detectors. The free areal exhalation rate was measured by the sealed cup-technique, whereas the radium content was obtained by the alpha-autoradiographic method. The calibration coefficient for thoron measurements in air using cylindrical cup equipped with LR-115 detector was estimated. Moreover, the calibration coefficients for measurements of the specific activities of 224Ra and 226Ra were also evaluated. New method was developed for evaluating the emanation coefficient as well as the diffusion coefficient of radon isotopes in the studied materials.

  15. Novel Usage for a Cosmic Ray Detector: Study of Lightning at Telescope Array

    NASA Astrophysics Data System (ADS)

    Belz, John; Okuda, Takeshi

    We describe observations performed at the Telescope Array Observatory in which "bursts" of air shower triggers of the surface detector occur in close temporal and spatial coincidence with lighting. These events appear to be consistent with other observations of high-energy particle showers produced by lightning. Telescope Array has the ability to reconstruct these showers using modified UHECR air shower reconstruction techniques, and thus determine the source of particles in the atmospheric breakdown. We describe new efforts to deploy lightning mapping detectors at the Telescope Array site which will enable further study of this phenomenon, along with enabling us to search for evidence of lightning strikes being "seeded" under certain atmospheric conditions by the passage of a UHECR air shower.

  16. Study of gain phenomenon in lateral metal-semiconductor-metal detectors for indirect conversion medical imaging

    NASA Astrophysics Data System (ADS)

    Abbaszadeh, Shiva; Allec, Nicholas; Wang, Kai; Chen, Feng; Karim, Karim S.

    2011-03-01

    Previously, metal-semiconductor-metal (MSM) lateral amorphous selenium (a-Se) detectors have been proposed for indirect detector medical imaging applications. These detectors have raised interest due to their high-speed and photogain. The gain measured from these devices was assumed to have been photoconductive gain; however the origin of this gain was not fully understood. In addition, whether or not there was any presence of photocurrent multiplication gain was not investigated. For integration-type applications photocurrent multiplication gain is desirable since the total collected charge can be greater than the total number of absorbed photons. In order to fully appreciate the value of MSM devices and their benefit for different applications, whether it is counting or integration applications, we need to investigate the responsible mechanisms of the observed response. In this paper, we systematically study, through experimental and theoretical means, the nature of the photoresponse and its responsible mechanisms. This study also exposes the possible means to increase the performance of the device and under what conditions it will be most beneficial.

  17. R&D Studies of a Lead-Scintillating Fiber Calorimeter as a STAR Forward Detector

    NASA Astrophysics Data System (ADS)

    Shanmuganathan, Prashanth; STAR Collaboration

    2015-10-01

    A forward upgrade of the STAR detector will achieve several physics goals. Examples are studying the internal structure of nucleons and nuclei through measurement of di-jets and Drell-Yan and improvements in the resolution of energy weighted event plane determination for study of more central and more peripheral events in heavy-ion collisions. The AGS E864 lead-scintillating fiber calorimeter cells ((10 cm) 2 × 117 cm) were repurposed by pixelizing their readout into a three by three array of (3 . 3 cm) 2 pixels. A prototype six by six array of these cells (324 pixels) was mounted on the west side of the STAR detector during Run14 and events from 3He+Au collisions at √{sNN} = 200 GeV were recorded. The detector response was simulated by a GEANT model using HIJING particle production. Further tests of the pixelized cells were conducted at the Fermilab Test Beam Facility. In this talk, we will present the calorimeter response in 3He+Au collisions using reconstructed π0 from clusters formed from energy deposition by π0 decay gammas. Energy resolution and shower shapes from pixelization are also discussed using test beam data and simulations.

  18. A Deuterated Neutron Detector Array For Nuclear (Astro)Physics Studies

    NASA Astrophysics Data System (ADS)

    Almaraz-Calderon, Sergio; Asher, B. W.; Barber, P.; Hanselman, K.; Perello, J. F.

    2016-09-01

    The properties of neutron-rich nuclei are at the forefront of research in nuclear structure, nuclear reactions and nuclear astrophysics. The advent of intense rare isotope beams (RIBs) has opened a new door for studies of systems with very short half-lives and possible fascinating properties. Neutron spectroscopic techniques become increasingly relevant when these neutron rich nuclei are used in a variety of experiments. At Florida State University, we are developing a neutron detector array that will allow us to perform high-resolution neutron spectroscopic studies with stable and radioactive beams. The neutron detection system consists of 16 deuterated organic liquid scintillation detectors with fast response and pulse-shape discrimination capabilities. In addition to these properties, there is the potential to use the structure in the pulse-height spectra to extract the energy of the neutrons and thus produce directly excitation spectra. This type of detector uses deuterated benzene (C6D6) as the liquid scintillation medium. The asymmetric nature of the scattering between a neutron and a deuterium in the center of mass produces a pulse-height spectrum from the deuterated scintillator which contains useful information on the initial energy of the neutron. Work supported in part by the State of Florida and NSF Grant No. 1401574.

  19. Study of the effect of the stress on CdTe nuclear detectors

    SciTech Connect

    Ayoub, M.; Radley, I.; Mullins, J. T.; Hage-Ali, M.

    2013-09-14

    CdTe detectors are commonly used for X and γ ray applications. The performance of these detectors is strongly affected by different types of mechanical stress; such as that caused by differential expansion between the semiconductor and its intimate metallic contacts and that caused by applied pressure during the bonding process. The aim of this work was to study the effects of stress on the performance of CdTe detectors. A difference in expansion coefficients induces transverse stress under the metallic contact, while contact pressure induces longitudinal stress. These stresses have been simulated by applying known static pressures. For the longitudinal case, the pressure was applied directly to the metallic contact; while in the transverse case, it was applied to the side. We have studied the effect of longitudinal and transverse stresses on the electrical characteristics including leakage current measurements and γ-ray detection performance. We have also investigated induced defects, their nature, activation energies, cross sections, and concentrations under the applied stress by using photo-induced current transient spectroscopy and thermoelectric effect spectroscopy techniques. The operational stress limit is also given.

  20. Neutrino oscillations with a proton driver upgrade and an off-axis detector: A Case study

    SciTech Connect

    Barenboim, Gabriela; De Gouvea, Andre; Szleper, Michal; Velasco, Mayda

    2002-04-01

    We study the physics capabilities of the NuMI beamline with an off-axis highly-segmented iron scintillator detector and with the inclusion of the currently under study proton driver upgrade. We focus on the prospects for the experimental determination of the remaining neutrino oscillation parameters, assuming different outcomes for experiments under way or in preparation. An optimization of the beam conditions and detector location for the detection of the nu_mu to nu_e transitions is discussed. Different physics scenarios were considered, depending on the actual solution of the solar neutrino puzzle. If KamLAND measures Delta m^2_solar, we find it possible to measure both |U_{e3}|^2 and the CP violating phase delta within a viable exposure time, assuming a realistic detector and a complete data analysis. Exposure to both neutrino and antineutrino beams is necessary. We can, in addition, shed light on Delta m^2_solar if its value is at the upper limit of KamLAND sensitivity (i.e. the precise value of Delta m^2_solar remains unknown even after KamLAND). If the solar neutrino solution is not in the LMA region, we can measure |U_{e3}|^2 and determine the neutrino mass hierarchy. The existence of the proton driver is vital for the feasibility of most of these measurements.

  1. Radiation hardness study of Silicon Detectors for the CMS High Granularity Calorimeter (HGCAL)

    NASA Astrophysics Data System (ADS)

    Currás, E.; Mannelli, M.; Moll, M.; Nourbakhsh, S.; Steinbrueck, G.; Vila, I.

    2017-02-01

    The high luminosity LHC (HL-LHC or Phase-II) is expected to increase the instantaneous luminosity of the LHC by a factor of about five, delivering 0~25 fb ‑1 per year between 2025 and 2035. Under these conditions the performance degradation of detectors due to integrated radiation dose/fluence will need to be addressed. The CMS collaboration is planning to upgrade many detector components, including the forward calorimeters. The replacement for the existing endcap preshower, electromagnetic and hadronic calorimeters is called the High Granularity Calorimeter (HGCAL) and it will be realized as a sampling calorimeter, including 40 layers of silicon detectors totalling 600 m2. The sensors will be realized as pad detectors with cell size between 0.5 and 1.0 cm2 and an active thickness between 100 μm and 300 μm depending on their location in the endcaps. The thinner sensors will be used in the highest radiation environment. For an integrated luminosity of 3000 fb ‑1, the electromagnetic calorimeter will have to sustain a maximum integrated dose of 1.5 MGy and neutron fluences of 1.0×1016 neq/cm2. A tolerance study after neutron irradiation of 300 μm, 200 μm, 100 μm and 50 μm n-on-p and p-on-n silicon pads irradiated to fluences up to 1.6×1016 neq/cm2 is presented. The main properties of these diodes have been studied before and after irradiation: leakage current, capacitance, charge collection efficiency with laser and sensitivity to minimum ionizing particles with radioactive source (90Sr). The results show a good performance even after the most extreme irradiation.

  2. CyberKnife beam output factor measurements: A multi-site and multi-detector study.

    PubMed

    Masi, Laura; Russo, Serenella; Francescon, Paolo; Doro, Raffaela; Frassanito, Maria Cristina; Fumagalli, Maria Luisa; Reggiori, Giacomo; Marinelli, Marco; Redaelli, Irene; Pimpinella, Maria; Verona Rinati, Gianluca; Siragusa, Carmelo; Vigorito, Sabrina; Mancosu, Pietro

    2016-12-01

    New promising detectors are available for measuring small field size output factors (OFs). This study focused on a multicenter evaluation of two new generation detectors for OF measurements on CyberKnife systems. PTW-60019 microDiamond and W1 plastic scintillation detector (PSD) were used to measure OFs on eight CyberKnife units of various generations for 5-60mm fixed cones. MicroDiamond and PSD OF were compared to routinely used silicon diodes data corrected applying published Monte Carlo (MC) factors. PSD data were corrected for Čerenkov Light Ratio (CLR). The uncertainties related to CLR determination were estimated. Considering OF values averaged over all centers, the differences between MC corrected diode and the other two detectors were within 1.5%. MicroDiamond exhibited an over-response of 1.3% at 7.5mm and a trend inversion at 5mm with a difference of 0.2%. This behavior was consistent among the different units. OFs measured by PSD slightly under-responded compared to MC corrected diode for the smaller cones and the differences were within 1%. The observed CLR variability was 2.5% and the related variation in OF values was 1.9%. This study indicates that CyberKnife microDiamond OF require corrections below 2%. The results are enhanced by the consistency observed among different units. Scintillator shows a good agreement to MC corrected diode but CLR determination remains critical requiring further investigations. The results emphasized the value of a multi-center validation over a single center approach. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  3. Detailed Studies of Pixelated CZT Detectors Grown with the Modified Horizontal Bridgman Method

    NASA Technical Reports Server (NTRS)

    Jung, I.; Krawczynski, H.; Burger, A.; Guo, M.; Groza, M.

    2007-01-01

    The detector material Cadmium Zinc Telluride (CZT) achieves excellent spatial resolution and good energy resolution over a broad energy range, several keV up to some MeV. Presently, there are two main methods to grow CZT crystals, the Modified High-Pressure Bridgman (MHB) and the High-Pressure Bridgman (HPB) process. The study presented in this paper is based on MHB CZT substrates from the company Orbotech Medical Solutions Ltd. [Orbotech Medical Solutions Ltd., 10 Plaut St., Park Rabin, P.O. Box 2489, Rehovot, Israel, 76124]. Former studies have shown that high-work-function materials on the cathode side reduce the leakage current and, therefore, improve the energy resolution at lower energies. None of the studies have emphasized on the anode contact material. Therefore, we present in this paper the result of a detailed study in which for the first time the cathode material was kept constant and the anode material was varied. We used four different anode materials: Indium, Titanium, Chromium and Gold, metals with work-functions between 4.1 eV and 5.1 eV. The detector size was 2.0 x 2.0 x 0.5 cu cm with 8 x 8 pixels and a pitch of 2.46 mm. The best performance was achieved with the low-work-function materials Indium and Titanium with energy resolutions of 2.0 keV (at 59 keV) and 1.9 keV (at 122 keV) for Titanium and 2.1 keV (at 59 keV) and 2.9 keV (at 122 keV) for Indium. Taking into account the large pixel pitch of 2.46 mm, these resolutions are very competitive in comparison to those achieved with detectors made of material produced with the more expensive conventional HPB method. We present a detailed comparison of our detector response with 3D simulations. The latter comparisons allow us to determine the mobility-lifetime-products (mu tau-products) for electrons and holes. Finally, we evaluated the temperature dependency of the detector performance and ls-products. For many applications temperature dependence is important, therefore, we extended the scope of

  4. A Prototype PET Scanner with DOI-Encoding Detectors

    PubMed Central

    Yang, Yongfeng; Wu, Yibao; Qi, Jinyi; St. James, Sara; Du, Huini; Dokhale, Purushottam A.; Shah, Kanai S.; Farrell, Richard; Cherry, Simon R.

    2009-01-01

    Detectors with depth-encoding allow a PET scanner to simultaneously achieve high sensitivity and high spatial resolution. Methods A prototype PET scanner, consisting of depth-encoding detectors constructed by dual-ended readout of lutetium oxyorthosilicate (LSO) arrays with two position sensitive avalanche photodiodes (PSAPDs), was developed. The scanner consisted of two detector plates, each with 4 detector modules. The LSO arrays consisted of 7×7 elements, with a crystal size of 0.9225×0.9225×20 mm3 with a pitch of 1.0 mm. The active area of the PSAPDs was 8×8 mm2. The performance of individual detector modules was characterized. A line source phantom and a hot rod phantom were imaged on the prototype scanner in two different scanner configurations. The images were reconstructed using 20, 10, 5, 2 and 1 DOI bins to demonstrate the effects of DOI resolution on reconstructed image resolution and visual image quality. Results The flood histograms measured from the sum of both PSAPD signals were only weakly depth-dependent and excellent crystal identification was obtained at all depths. The flood histograms improved as the detector temperature decreased. DOI resolution and energy resolution improved significantly as the temperature decreased from 20 °C to 10 °C, but only slightly with a subsequent temperature decrease to 0 °C. A full-width at half-maximum (FWHM) DOI resolution of 2 mm and an FWHM energy resolution of 15% were obtained at a temperature of 10 °C. Phantom studies showed that DOI measurements significantly improved the reconstructed image resolution. In the first scanner configuration (parallel detector planes) the image resolution at the center of field of view (CFOV) was 0.9 mm FWHM with 20 DOI bins and 1.6 mm with one DOI bin. In the second scanner configuration (detector planes at a 40° angle) the image resolution at the CFOV was 1.0 mm FWHM with 20 DOI bins and was not measurable when using only one bin. Conclusions PET scanners based on

  5. Wnt activity and basal niche position sensitize intestinal stem and progenitor cells to DNA damage.

    PubMed

    Tao, Si; Tang, Duozhuang; Morita, Yohei; Sperka, Tobias; Omrani, Omid; Lechel, André; Sakk, Vadim; Kraus, Johann; Kestler, Hans A; Kühl, Michael; Rudolph, Karl Lenhard

    2015-03-04

    Aging and carcinogenesis coincide with the accumulation of DNA damage and mutations in stem and progenitor cells. Molecular mechanisms that influence responses of stem and progenitor cells to DNA damage remain to be delineated. Here, we show that niche positioning and Wnt signaling activity modulate the sensitivity of intestinal stem and progenitor cells (ISPCs) to DNA damage. ISPCs at the crypt bottom with high Wnt/β-catenin activity are more sensitive to DNA damage compared to ISPCs in position 4 with low Wnt activity. These differences are not induced by differences in cell cycle activity but relate to DNA damage-dependent activation of Wnt signaling, which in turn amplifies DNA damage checkpoint activation. The study shows that instructed enhancement of Wnt signaling increases radio-sensitivity of ISPCs, while inhibition of Wnt signaling decreases it. These results provide a proof of concept that cell intrinsic levels of Wnt signaling modulate the sensitivity of ISPCs to DNA damage and heterogeneity in Wnt activation in the stem cell niche contributes to the selection of ISPCs in the context of DNA damage.

  6. Studies of Laser Interferometer Design and a Vibration Isolation System for Interferometric Gravitational Wave Detectors.

    NASA Astrophysics Data System (ADS)

    Giaime, Joseph Anthony

    1995-01-01

    Two techniques are developed that are needed in the design of an interferometric gravitational wave (GW) detector such as the LIGO, or Long-baseline Interferometric Gravitational-wave Observatory. The detector sensitivity of a long-baseline instrument is studied. A multi-layer mechanical isolation stack to filter seismic noise from test masses is designed, modeled and tested in vacuum. This is a four-stage elastomer (spring) and stainless steel (mass) stack, consisting of a table resting on three separate legs of three layers each. The visco-elastic properties of elastomer springs are exploited to damp the stack's normal modes while providing rapid roll-off of stack transmission above these modal frequencies. The stack's transmission of base motion to top motion is measured in vacuum and compared with 3-D finite-element models. In one tested configuration, at 100 Hz, horizontal transmission is 10^{-7}, vertical transmission is 3 times 10^{-6}, and the cross-coupling terms are between these values. A length detection scheme using RF phase modulated light and synchronous detection is developed for Fabry -Perot arm power-recycled Michelson interferometer GW detectors. This scheme uses an external Mach-Zehnder interferometer to measure the GW signal, and a frequency-shifted subcarrier to measure ancillary interferometer degrees of freedom. Use of the Mach-Zehnder allows rejection of laser source amplitude noise from the output, as well as the ability to exploit well-balanced Fabry-Perot arms to reject frequency noise from the output. A long baseline GW detector using these techniques should meet the LIGO initial goal sensitivity to GW strain of h_{rm RMS} = 10^ {-21} at 100 Hz. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-1307. Ph. 617 -253-5668; Fax 617-253-1690.).

  7. Monte Carlo study of the time resolution of scintillating fibre detectors

    NASA Astrophysics Data System (ADS)

    Ziembicki, M.; Marzec, J.; Dziewiecki, M.

    2007-08-01

    This paper presents the results of a Monte Carlo study of the time resolution of a scintillating fibre detector and analyses its dependence on the various aspects of detector construction. The estimations of the theoretical time resolutions for detectors with different numbers of fibre layers and different types of acrylic-based fibre coatings are presented. The method is suggested to decrease the rate counting effects encountered in high rate applications. It has been observed that for dual cladding fibres with a fluorinated polymer used for the outer cladding, the most significant factor contributing to the time resolution is the number of fibre layers, with the fibre coating being the marginal one. Another observation shows that the introduction of a gap between the fibre and the photomultiplier glass window allows the reduction of the number of photoelectrons by 25% with only a slight decrease in the time resolution, which may be helpful in decreasing the pulse pile-up effects and the photomultiplier gain, commonly observed under high rate conditions.

  8. Tragaldabas: a muon ground-based detector for the study of the solar activity; first observations

    NASA Astrophysics Data System (ADS)

    José Blanco, Juan

    2016-04-01

    A new RPC-based cosmic ray detector, TRAGALDABAS (acronym of "TRAsGo for the AnaLysis of the nuclear matter Decay, the Atmosphere, the earth's B-field And the Solar activity") has been installed at the Univ. of Santiago de Compostela, Spain (N:42°52'34",W:8°33'37"). The detector, in its present layout, consists of three 1.8 m2 planes of three 1mm-gap glass RPCs. Each plane is readout with 120 pads with grounded guard electrodes between them to minimize the crosstalk noise. The main performances of the detectors are: an arrival time resolution of about ~300 ps, a tracking angular resolution below 3°, a detection efficiency close to 1, and a solid angle acceptance of ~5 srad. TRAGALDABAS will be able to monitor the cosmic ray low energy component strongly modulated by solar activity by mean the observation of secondary muons from the interaction between cosmic rays and atmospheric molecules. Its cadence and its angular resolution will allow to study in detail, small variations in cosmic ray anisotropy. These variations can be a key parameter to understand the effect of solar disturbances on the propagation of cosmic ray in the inner heliosphere and, maybe, provide a new tool for space weather analysis. In this work first TRAGALDABAS observations of solar events are shown

  9. Photoluminescence study of surface treatment effects on detector-grade CdTe:In

    NASA Astrophysics Data System (ADS)

    Zázvorka, J.; Hlídek, P.; Franc, J.; Pekárek, J.; Grill, R.

    2016-02-01

    We studied the influence of standard surface treatment techniques on the generation of defects with deep levels that can act as trapping and recombination centers for photo-generated carriers in detector-grade CdTe:In material grown via the Vertical-Gradient-Freeze (VGF) method. We measured room-temperature contactless resistivity, photoconductivity, detector performance and low-temperature photoluminescence dependence on the surface preparation of the material and observed changes in the resistivity and photoluminescence signal after etching a 5 μm thick surface layer. We found four deep levels in the range of 0.8-1.3 eV. The relative ratio of their photoluminescence maxima changes after mechanical polishing and chemical etching treatment. A deep level at ˜0.9 eV seems to be connected to mechanical stress induced by polishing of the sample with a standard 1 μm alumina abrasive and influences the charge collection efficiency of the detector.

  10. Stroke Detector and Structure Based Models for Character Recognition: A Comparative Study.

    PubMed

    Shi, Cun-Zhao; Gao, Song; Liu, Meng-Tao; Qi, Cheng-Zuo; Wang, Chun-Heng; Xiao, Bai-Hua

    2015-12-01

    Characters, which are man-made symbols composed of strokes arranged in a certain structure, could provide semantic information and play an indispensable role in our daily life. In this paper, we try to make use of the intrinsic characteristics of characters and explore the stroke and structure-based methods for character recognition. First, we introduce two existing part-based models to recognize characters by detecting the elastic strokelike parts. In order to utilize strokes of various scales, we propose to learn the discriminative multi-scale stroke detector-based representation (DMSDR) for characters. However, the part-based models and DMSDR need to manually label the parts or key points for training. In order to learn the discriminative stroke detectors automatically, we further propose the discriminative spatiality embedded dictionary learning-based representation (DSEDR) for character recognition. We make a comparative study of the performance of the tree-structured model (TSM), mixtures-of-parts TSM, DMSDR, and DSEDR for character recognition on three challenging scene character recognition (SCR) data sets as well as two handwritten digits recognition data sets. A series of experiments is done on these data sets with various experimental setup. The experimental results demonstrate the suitability of stroke detector-based models for recognizing characters with deformations and distortions, especially in the case of limited training samples.

  11. A study of atmospheric neutrino oscillations in the MINOS far detector

    SciTech Connect

    Blake, Andrew

    2005-08-01

    In recent years, neutrino experiments have begun to challenge the Standard Model assumption that neutrinos are massless. There is now firm evidence that neutrinos undergo quantum mechanical oscillations between flavors. This would imply that neutrinos possess mass and that neutrino flavors are mixed by the weak interaction. Atmospheric neutrinos, produced by the interactions of cosmic rays in the earth's atmosphere, can be used to study these oscillations. The MINOS Far Detector has been collecting atmospheric neutrino data since 1st August 2003 using a 5.4 kT steel-scintillator sampling calorimeter located 700 m underground (2100 m water-equivalent) at the Soudan Underground Laboratory, Minnesota. The Far Detector is the first massive underground detector to possess a magnetic field. This makes the separation of atmospheric vμ and $\\bar{v}$μ charged current interactions possible for the first time. This thesis presents a study of atmospheric neutrino oscillations in the Far Detector, based on a total detector exposure of 316 days (3.3 kT-Yrs fiducial exposure). The separation of atmospheric neutrinos from the high background of cosmic muons is outlined. A total of 82 candidate events are observed, with an expectation of 109.9 ± 21.4 events in the absence of oscillations. Of the selected events, 40 events have a clearly identified charge, with 27 events tagged as neutrinos and 13 events tagged at anti-neutrinos. This represents the first direct observation of atmospheric vμ and $\\bar{v}$μ charged current interactions. A maximum likelihood analysis us used to determine the allowed region for the oscillation parameters Δm$2\\atop{23}$ and sin223. This disfavors the null oscillation hypothesis at the 79% confidence level. With the current low statistics, the sensitivity of the analysis is limited. The expected future sensitivity of the atmospheric neutrino analysis is discussed.

  12. Upgrading FLIR NanoRaider with the next Generation of CdZnTe Detectors. Goal - Integrate VFG detectors into FLIR R200. Advanced Virtual Grid ASIC (AVG-ASIC).

    SciTech Connect

    Bolotnikov, Aleksey; Cui, Yonggang; Vernon, Emerson; De Geronimo, Gianluigi

    2016-06-01

    This document presents motivations, goals and the current status of this project; development (fabrication, performance) of position-sensitive virtual Frisch-grid detectors proposed for nanoRaider, an instrument commonly used by nuclear inspectors; ASIC developments for CZT detectors; and the electronics development for the detector prototype..

  13. NUV Detector Dark Monitor

    NASA Astrophysics Data System (ADS)

    Cox, Colin

    2011-10-01

    Perform routine monitoring of MAMA detector dark current. The main purpose isto look for evidence of a change in the dark rates, both to track on-orbit timedependence and to check for a detector problem developing. The spatial distribution of dark rates on the detector and the effect of SAA will also be studied.

  14. NUV Detector Dark Monitor

    NASA Astrophysics Data System (ADS)

    Ely, Justin

    2012-10-01

    Perform routine monitoring of MAMA detector dark current. The main purpose isto look for evidence of a change in the dark rates, both to track on-orbit timedependence and to check for a detector problem developing. The spatial distribution of dark rates on the detector and the effect of SAA will also be studied.

  15. NUV Detector Dark Monitor

    NASA Astrophysics Data System (ADS)

    Ely, Justin

    2013-10-01

    Perform routine monitoring of MAMA detector dark current. The main purpose isto look for evidence of a change in the dark rates, both to track on-orbit timedependence and to check for a detector problem developing. The spatial distribution of dark rates on the detector and the effect of SAA will also be studied.

  16. NUV Detector Dark Monitor

    NASA Astrophysics Data System (ADS)

    Zheng, Wei

    2010-09-01

    Perform routine monitoring of MAMA detector dark current. The main purpose isto look for evidence of a change in the dark rates, both to track on-orbit timedependence and to check for a detector problem developing. The spatial distribution of dark rates on the detector and the effect of SAA will also be studied.

  17. General formalism for the study of activation: application to radiochemical detectors

    SciTech Connect

    Poppe, C.H.

    1982-09-24

    This paper develops mathematical techniques required for the study of neutron-induced activation of importance to fission and fusion devices - reactors, nuclear weapons, etc. The formalism is presented as a guide for examining the dependence of activation products on flux time history, spatial gradients and the sensitivity to the assumed reactions and cross sections. Exact solutions in powers of the neutron fluence are presented and examined in various limits. As an example, radiochemical threshold (n,2n) detectors used to diagnose thermonuclear explosions are studied using approximations to these solutions. In particular, approximate formulas for the sensitivity of the radiochemical products to different cross sections are derived.

  18. Light sharing in multi-flat-panel-PMT PEM detectors.

    PubMed

    Raylman, Raymond R; Majewski, Stan; Mayhugh, Michael R

    2006-01-01

    Large are a detectors, such as those used in positron emission mammography (PEM) and scintimammography, utilize arrays of discrete semtillator elements mounted on arrays of position sensitive photomultiplier tubes (PSPMT). Scintillator elements can be packed very densely (minimizing area between elements), allowing good detection sensitivity and spatial resolution. And, while new flat panel PSPMTS have minimal inactive edges, when they are placed in arrays significant dead spaces where scintillation light is undetectable are created. To address this problem, a light guide is often placed between the detector and PSPMT array to spread scintillation light so that these gaps can be bridged. In this investigation we studied the effect of light guides of various thickness on system performance. A 10x10 element array of LYSO detector elements was coupled to the center of a 2x2 array of PSPMTs through varying thicknesses (1 to 4 mm) of UV glass. The spot size of the imaged elements and distortions in the regular square pattern of the imaged scintillator arrays were evaluated. Energy resolution was measured by placing single elements of LYSO at several locations of the PSPMT array. Spatial distortions in the images of the array were reduced by using thicker light guides (3-4 mm). Use of thicker light guides, however, resulted in reduced pixel resolution and slight degradation of energy resolution. Therefore, some loss of pixel and energy resolution will accompany the use of thick light guides (minimum of 3 mm) required for optimum identification of detector elements.

  19. A novel fast-neutron detector concept for energy-selective imaging and imaging spectroscopy

    SciTech Connect

    Cortesi, M.; Prasser, H.-M.; Dangendorf, V.; Zboray, R.

    2014-07-15

    We present and discuss the operational principle of a new fast-neutron detector concept suitable for either energy-selective imaging or for imaging spectroscopy. The detector is comprised of a series of energy-selective stacks of converter foils immersed in a noble-gas based mixture, coupled to a position-sensitive charge readout. Each foil in the various stacks is made of two layers of different thicknesses, fastened together: a hydrogen-rich (plastic) layer for neutron-to-proton conversion, and a hydrogen-free coating to selectively stop/absorb the recoil protons below a certain energy cut-off. The neutron-induced recoil protons, that escape the converter foils, release ionization electrons in the gas gaps between consecutive foils. The electrons are then drifted towards and localized by a position-sensitive charge amplification and readout stage. Comparison of the images detected by stacks with different energy cut-offs allows energy-selective imaging. Neutron energy spectrometry is realized by analyzing the responses of a sufficient large number of stacks of different energy response and unfolding techniques. In this paper, we present the results of computer simulation studies and discuss the expected performance of the new detector concept. Potential applications in various fields are also briefly discussed, in particularly, the application of energy-selective fast-neutron imaging for nuclear safeguards application, with the aim of determining the plutonium content in Mixed Oxide (MOX) fuels.

  20. A novel fast-neutron detector concept for energy-selective imaging and imaging spectroscopy.

    PubMed

    Cortesi, M; Dangendorf, V; Zboray, R; Prasser, H-M

    2014-07-01

    We present and discuss the operational principle of a new fast-neutron detector concept suitable for either energy-selective imaging or for imaging spectroscopy. The detector is comprised of a series of energy-selective stacks of converter foils immersed in a noble-gas based mixture, coupled to a position-sensitive charge readout. Each foil in the various stacks is made of two layers of different thicknesses, fastened together: a hydrogen-rich (plastic) layer for neutron-to-proton conversion, and a hydrogen-free coating to selectively stop/absorb the recoil protons below a certain energy cut-off. The neutron-induced recoil protons, that escape the converter foils, release ionization electrons in the gas gaps between consecutive foils. The electrons are then drifted towards and localized by a position-sensitive charge amplification and readout stage. Comparison of the images detected by stacks with different energy cut-offs allows energy-selective imaging. Neutron energy spectrometry is realized by analyzing the responses of a sufficient large number of stacks of different energy response and unfolding techniques. In this paper, we present the results of computer simulation studies and discuss the expected performance of the new detector concept. Potential applications in various fields are also briefly discussed, in particularly, the application of energy-selective fast-neutron imaging for nuclear safeguards application, with the aim of determining the plutonium content in Mixed Oxide (MOX) fuels.

  1. A novel fast-neutron detector concept for energy-selective imaging and imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Cortesi, M.; Dangendorf, V.; Zboray, R.; Prasser, H.-M.

    2014-07-01

    We present and discuss the operational principle of a new fast-neutron detector concept suitable for either energy-selective imaging or for imaging spectroscopy. The detector is comprised of a series of energy-selective stacks of converter foils immersed in a noble-gas based mixture, coupled to a position-sensitive charge readout. Each foil in the various stacks is made of two layers of different thicknesses, fastened together: a hydrogen-rich (plastic) layer for neutron-to-proton conversion, and a hydrogen-free coating to selectively stop/absorb the recoil protons below a certain energy cut-off. The neutron-induced recoil protons, that escape the converter foils, release ionization electrons in the gas gaps between consecutive foils. The electrons are then drifted towards and localized by a position-sensitive charge amplification and readout stage. Comparison of the images detected by stacks with different energy cut-offs allows energy-selective imaging. Neutron energy spectrometry is realized by analyzing the responses of a sufficient large number of stacks of different energy response and unfolding techniques. In this paper, we present the results of computer simulation studies and discuss the expected performance of the new detector concept. Potential applications in various fields are also briefly discussed, in particularly, the application of energy-selective fast-neutron imaging for nuclear safeguards application, with the aim of determining the plutonium content in Mixed Oxide (MOX) fuels.

  2. Performance study of polycrystalline CVD diamond detectors for fast neutron monitoring

    SciTech Connect

    Singh, Arvind Kumar, Amit Topkar, Anita

    2014-04-24

    Diamond detectors using polycrystalline CVD diamond substrates of thickness 300μm and 100μm were fabricated for fast neutron monitoring application.. The characterization of detectors was carried out using various tests such as leakage current, capacitance and alpha particle response. The performance of detectors was evaluated for fast neutrons at different neutron yields. The results presented in this work demonstrate that the diamond detectors will be suitable for monitoring fast neutrons.

  3. A dynamic x-ray diffraction study of anesthesia action. Thickening of the myelin membrane by n-pentane.

    PubMed

    Padron, R; Mateu, L; Requena, J

    1979-04-19

    The structural changes induced in the myelin sheath by n-pentane nerve impulse blockage were studied by small-angle X-ray diffraction using a linear position-sensitive detector. The results show that the thickness of the myelin period lattice increases from 170 to 180 A during n-pentane treatment.

  4. Electrical Signal Path Study and Component Assay for the MAJORANA N-Type Segmented Contact Detector

    SciTech Connect

    Amman, Mark; Bergevin, Marc; Chan, Yuen-Dat; Detwiler, Jason A.; Fujikawa, Brian .; Lesko, Kevin T.; Luke, Paul N.; Prior, Gersende; Poon, Alan W.; Smith, Alan R.; Vetter, Kai; Yaver, Harold; Zimmermann, Sergio

    2009-02-24

    The purpose of the present electrical signal path study is to explore the various issues related to the deployment of highly-segmented low-background Ge detectors for the MAJORANA double-beta decay experiment. A significant challenge is to simultaneously satisfy competing requirements for the mechanical design, electrical readout performance, and radiopurity specifications from the MAJORANA project. Common to all rare search experiments, there is a very stringent limit on the acceptable radioactivity level of all the electronics components involved. Some of the findings are summarized in this report.

  5. Extensive studies of MRS APDs for plastic scintillator muon veto detectors of cryogenic experiments

    NASA Astrophysics Data System (ADS)

    Falkenstein, R.; Bezrukov, L. B.; Freund, K.; Golovin, A. V.; Golovin, V. M.; Grabmayr, P.; Jochum, J.; Lubsandorzhiev, B. K.; Lubsandorzhiev, N. B.; Poleshuk, R. V.; Polyansky, I. N.; Ritter, F.; Sailer, C.; Shaibonov, B. A. M.

    2012-12-01

    Low background experiments need active muon veto detectors to shield them from cosmic muons. Plastic scintillator panels with WLS fiber and multi-pixel Geiger-mode avalanche photodiodes readout are widely used in such experiments due to their compactness and robustness. In this paper, results from the study of the basic MRS APD parameters, such as breakdown voltages, quenching resistors, internal gain and dark count rates are presented, as well as temperature dependencies of some of these parameters. In a small fraction of the MRS APDs, some strange dips in the I-V curves just preceding the breakdown voltage point have been observed.

  6. Study of Double Pomeron Exchange with the SFM detector at the CERN ISR

    NASA Astrophysics Data System (ADS)

    Fischer, H. G.; Geist, W.; Makariev, M.

    2014-11-01

    Selected results from the study of Double Pomeron Exchange with the Split Field Magnet detector at the CERN Intersecting Storage Rings are presented. This concerns various general features of central pionic systems as well as the spectroscopy in the π+π- channel, emphasizing the production properties of the f2(1270) meson. This summary refers to a series of publications over a time span of 17 years based on the work of the CCHK1,2 and ABCDHW3-7 collaborations at the CERN ISR.

  7. Study of KS semileptonic decays and CPT test with the KLOE detector

    NASA Astrophysics Data System (ADS)

    Kamińska, Daria; KLOE-2 Collaboration

    2015-07-01

    Study of semileptonic decays of neutral kaons allows to perform a test of discrete symmetries, as well as basic principles of the Standard Model. In this paper a general review on dependency between charge asymmetry constructed for semileptonic decays of short- and long-lived kaons and CPT symmetry is given. The current status of determination of charge asymmetry for short-lived kaon, obtained by reconstruction of about 105 KS → πeν decays collected at DAΦNE with the KLOE detector is also reviewed.

  8. Neutron detectors at IPNS

    SciTech Connect

    Crawford, R.K.; Haumann, J.R.; Ostrowski, G.E.

    1990-01-01

    The heart of each time-of-flight neutron scattering instrument is its complement of detectors and the associated encoding and counting electronics. Currently there are ten fully-scheduled neutron scattering instruments in operation at IPNS, with three more instruments under development. Six of these instruments use position-sensitive neutron detectors (PSDs) of various types. These PSDs include a 30 cm {times} 30 cm, {approximately}3 mm resolution, neutron Anger camera area PSD with {sup 6}Li-glass scintillator; a 2.5 cm dia, {approximately}0.7 mm resolution, microchannel-plate area PSD with {sup 6}Li-glass scintillator; a 20 cm {times} 20 cm, {approximately}5 mm resolution, {sup 3}He proportional counter area PSD; a 40 cm {times} 40 cm, {approximately}4 mm resolution, {sup 3}He proportional counter area PSD; a flat 25 cm long, {approximately}1.6 mm resolution, {sup 3}He proportional counter linear PSD; and 160 cylindrical {sup 3}He proportional counter linear PSDs, each of which is 1.27 cm in dia and 60 cm long and has {approximately}14 mm resolution. In addition to these PSDs, {approximately}750 standard cylindrical {sup 3}He proportional counters of various sizes are utilized on IPNS instruments, and {approximately}20 BF{sub 3} pulsed ion chambers are in use as beam monitors. This paper discusses these various detectors and associated electronics, with emphasis on the instrumental specifications and the reasons for the selection of the different types of detectors. Observed performance of these detectors is also discussed. 19 refs., 5 figs., 2 tabs.

  9. Study of electrode pattern design for a CZT-based PET detector

    PubMed Central

    Gu, Y; Levin, C S

    2014-01-01

    We are developing a 1 mm resolution small animal positron emission tomography (PET) system using 3-D positioning Cadmium Zinc Telluride (CZT) photon detectors comprising 40 mm × 40 mm × 5 mm crystals metalized with a cross-strip electrode pattern with a 1 mm anode strip pitch. We optimized the electrode pattern design for intrinsic sensitivity and spatial, energy and time resolution performance using a test detector comprising cathode and steering electrode strips of varying dimensions. The study found 3 mm and 5 mm width cathode strips locate charge-shared photon interactions near cathode strip boundaries with equal precision. 3 mm width cathode strips exhibited large time resolution variability as a function of photon interaction location between the anode and cathode planes (~26 ns to ~127.5 ns FWHM for 0.5 mm and 4.2 mm depths, respectively). 5 mm width cathode strips by contrast exhibited more stable time resolution for the same interaction locations (~34 ns to ~83 ns FWHM), provided more linear spatial positioning in the direction orthogonal to the electrode planes, and as much as 68.4% improvement in photon sensitivity over the 3 mm wide cathode strips. The results were understood by analyzing the cathode strips’ weighting functions, which indicated a stronger “small pixel” effect in the 3 mm wide cathode strips. Photon sensitivity and anode energy resolution were seen to improve with decreasing steering electrode bias from 0 V to −80 V w.r.t the anode potential. A slight improvement in energy resolution was seen for wider steering electrode strips (400 μm vs. 100 μm) for charge-shared photon interactions. Although this study successfully focused on electrode pattern features for PET performance, the results are generally applicable to semiconductor photon detectors employing cross-trip electrode patterns. PMID:24786208

  10. Study of electrode pattern design for a CZT-based PET detector

    NASA Astrophysics Data System (ADS)

    Gu, Y.; Levin, C. S.

    2014-06-01

    We are developing a 1 mm resolution small animal positron emission tomography (PET) system using 3D positioning cadmium zinc telluride photon detectors comprising 40 mm × 40 mm × 5 mm crystals metalized with a cross-strip electrode pattern with a 1 mm anode strip pitch. We optimized the electrode pattern design for intrinsic sensitivity and spatial, energy and time resolution performance using a test detector comprising cathode and steering electrode strips of varying dimensions. The study found 3 and 5 mm width cathode strips locate charge-shared photon interactions near cathode strip boundaries with equal precision. 3 mm width cathode strips exhibited large time resolution variability as a function of photon interaction location between the anode and cathode planes (˜26 to ˜127.5 ns full width at half maximum (FWHM) for 0.5 mm and 4.2 mm depths, respectively). 5 mm width cathode strips by contrast exhibited more stable time resolution for the same interaction locations (˜34 to ˜83 ns FWHM), provided more linear spatial positioning in the direction orthogonal to the electrode planes, and as much as 68.4% improvement in photon sensitivity over the 3 mm wide cathode strips. The results were understood by analyzing the cathode strips’ weighting functions, which indicated a stronger ‘small pixel’ effect in the 3 mm wide cathode strips. Photon sensitivity and anode energy resolution were seen to improve with decreasing steering electrode bias from 0 to -80 V w.r.t. the anode potential. A slight improvement in energy resolution was seen for wider steering electrode strips (400 versus 100 µm) for charge-shared photon interactions. Although this study successfully focused on electrode pattern features for PET performance, the results are generally applicable to semiconductor photon detectors employing cross-trip electrode patterns.

  11. Study of electrode pattern design for a CZT-based PET detector.

    PubMed

    Gu, Y; Levin, C S

    2014-06-07

    We are developing a 1 mm resolution small animal positron emission tomography (PET) system using 3D positioning cadmium zinc telluride photon detectors comprising 40 mm × 40 mm × 5 mm crystals metalized with a cross-strip electrode pattern with a 1 mm anode strip pitch. We optimized the electrode pattern design for intrinsic sensitivity and spatial, energy and time resolution performance using a test detector comprising cathode and steering electrode strips of varying dimensions. The study found 3 and 5 mm width cathode strips locate charge-shared photon interactions near cathode strip boundaries with equal precision. 3 mm width cathode strips exhibited large time resolution variability as a function of photon interaction location between the anode and cathode planes (~26 to ~127.5 ns full width at half maximum (FWHM) for 0.5 mm and 4.2 mm depths, respectively). 5 mm width cathode strips by contrast exhibited more stable time resolution for the same interaction locations (~34 to ~83 ns FWHM), provided more linear spatial positioning in the direction orthogonal to the electrode planes, and as much as 68.4% improvement in photon sensitivity over the 3 mm wide cathode strips. The results were understood by analyzing the cathode strips' weighting functions, which indicated a stronger 'small pixel' effect in the 3 mm wide cathode strips. Photon sensitivity and anode energy resolution were seen to improve with decreasing steering electrode bias from 0 to -80 V w.r.t. the anode potential. A slight improvement in energy resolution was seen for wider steering electrode strips (400 versus 100 µm) for charge-shared photon interactions. Although this study successfully focused on electrode pattern features for PET performance, the results are generally applicable to semiconductor photon detectors employing cross-trip electrode patterns.

  12. Experimental Study of Three-Nucleon Dynamics in the Dp Breakup Collisions Using the WASA Detector

    NASA Astrophysics Data System (ADS)

    Kłos, B.; Ciepał, I.; Jamróz, B.; Khatri, G.; Kistryn, S.; Kozela, A.; Magiera, A.; Parol, W.; Skwira-Chalot, I.; Stephan, E.

    2017-03-01

    Until recently, all calculations of breakup observables were carried out in a non-relativistic regime. The relativistic treatment of the breakup reaction in 3 N system is quite a new achievement. The detailed study of various aspects of few-nucleon system dynamics in medium energy region, with a particular emphasis on investigation of relativistic effects and their interplay with three nucleon force (3NF) becomes feasible with increasing available energy in the three nucleon system. Therefore an experiment to investigate the ^1H(d, pp)n breakup cross section using a deuteron beam of 300, 340, 380 and 400 MeV and the WASA detector has been performed at COSY-Jülich. The almost 4π geometry of the WASA detector gives an unique possibility to study variety of kinematic configurations, which reveal different sensitivity to aspects of dynamics of the three nucleon system. The main steps of the analysis, including energy calibration, PID, normalization and efficiency studies, and their impact on the final accuracy of the result, are discussed.

  13. Development of the microchannel plate detector for FUV spectroscopy in the BepiColombo mission

    NASA Astrophysics Data System (ADS)

    Murakami, Go; Yoshioka, Kazuo; Sakai, Kouichi; Honma, Tatsuro; Yoshikawa, Ichiro; Maria, Jean-Luc; Quemerais, E.

    PHEBUS (Probing of Hermean Exosphere By Ultraviolet Spectroscopy) is a double ultraviolet spectrometer for the MPO spacecraft of the BepiColombo mission, which is dedicated to the study of the Mercury. The purpose of this instrument is to reveal the composition and the distribution of the Mercury's exosphere by detecting emission lines in the wavelength range from 55 to 315 nm. The instrument is basically composed of two ultraviolet spectrometers and one scanning mirror with a single axis of rotation. Each detector has a specific range of wavelengths: the Extreme Ultraviolet (EUV) channel from 55 to 155 nm, and the Far Ultraviolet (FUV) channel from 145 to 315 nm. The FUV detector consists of a MgF2 input window, a Cs2 Te photocathode, microchannel plates (MCPs), and a resistive anode encoder (RAE). We have manufactured and tested the optical prototype of the FUV detector. In a position-sensitive system with an RAE, the spatial resolution depends on the bias voltage applied to each part of the detector. We optimized the bias voltage and achieved a high spatial resolution of 45 m, corresponding to 480480 pixels. In addition, the long-term aging of the detector against incidence of photon flux was tested. Based on the result of our laboratory measurement, both gain and quantum efficiency of the MCPs will decrease by about 40% during the BepiColombo mission. In our presentation we report the specific performance of the optical prototype of the FUV detector.

  14. Performance of an AGATA asymmetric detector

    NASA Astrophysics Data System (ADS)

    Boston, A. J.; Dimmock, M. R.; Unsworth, C.; Boston, H. C.; Cooper, R. J.; Grint, A. N.; Harkness, L. J.; Lazarus, I. H.; Jones, M.; Nolan, P. J.; Oxley, D. C.; Simpson, J.; Slee, M.; Agata Collaboration

    2009-06-01

    High-resolution gamma-ray detectors based on high-purity germanium crystals (HPGe) are one of the key workhorses of experimental nuclear science. The technical development of such detector technology has been dramatic in recent years. Large volume, high-granularity, electrically segmented HPGe detectors have been realised and a methodology to improve position sensitivity using pulse-shape analysis coupled with the novel technique of gamma-ray tracking has been developed. Collaborations have been established in Europe (Advanced GAmma Tracking Array (AGATA)) [J. Simpson, Acta Phys. Pol. B 36 (2005) 1383] and the USA (GRETA/GRETINA) [C.W. Beausang, Nucl. Instr. and Meth. B 204 (2003)] to build gamma-ray tracking spectrometers. This paper discusses the performance of the first AGATA asymmetric detector that has been tested at the University of Liverpool. The use of a fully digital data acquisition system has allowed detector charge pulse shapes from a selection of well-defined photon interaction positions to be analysed, yielding important information on the position sensitivity of the detector.

  15. Impact of high energy resolution detectors on the performance of a PET system dedicated to breast cancer imaging.

    PubMed

    Levin, Craig S; Foudray, Angela M K; Habte, Frezghi

    2006-01-01

    We are developing a high resolution, high sensitivity PET camera dedicated to breast cancer imaging. We are studying two novel detector technologies for this imaging system: a scintillation detector comprising layers of small lutetium oxyorthosilicate (LSO) crystals coupled to new position sensitive avalanche photodiodes (PSAPDs), and a pure semiconductor detector comprising cadmium zinc telluride (CZT) crystal slabs with thin anode and cathode strips deposited in orthogonal directions on either side of each slab. Both detectors achieve 1 mm spatial resolution with 3-5 mm directly measured photon interaction depth resolution, which promotes uniform reconstructed spatial resolution throughout a compact, breast-size field of view. Both detector types also achieve outstanding energy resolution (<3% and <12%, respectively for LSO-PSAPD and CZT at 511 keV). This paper studies the effects that this excellent energy resolution has on the expected system performance. Results indicate the importance that high energy resolution and narrow energy window settings have in reducing background random as well as scatter coincidences without compromising statistical quality of the dedicated breast PET data. Simulations predict that using either detector type the excellent performance and novel arrangement of these detectors proposed for the system facilitate approximately 20% instrument sensitivity at the system center and a peak noise-equivalent count rate of >4 kcps for 200 microCi in a simulated breast phantom.

  16. Radiation Resistance Study of Semi-Insulating GaAs-Based Radiation Detectors to Extremely High Gamma Doses

    NASA Astrophysics Data System (ADS)

    Ly Anh, T.; Perd'ochová, A.; Nečas, V.; Pavlicová, V.

    2006-01-01

    In our previous paper [V. Nečas et al.: Nucl. Inst. and Meth. A 458 (2001) 348-351] we reported on the study on radiation stability of semi-insulating (SI) LEG GaAs detectors to doses of photons from 60Co up to 19.2 kGy. Later we presented a study, which covered radiation hardness to the same doses on the base of detector material itself, where strong dependence has been proved [T. Ly Anh et al., Proceedings of the XII th International Conference on Semiconducting and Insulating Materials (SIMC-XII-2002). Smolenice Castle, Slovakia (2002) 292-295 (0-7803-7418-5)]. In this paper we present both the key electrical and detection characteristics of SI GaAs radiation detectors prepared using substrates from four various supplies and two different types of contacts, which were exposed to several gamma doses from 60Co up to the integral dose of about 1 MGy. The obtained results show that SI LEG GaAs detectors provide good spectroscopic performances and even their slight improvement after low to middle gamma irradiation doses (3 -10 kGy) was observed. Further dose exposure caused the degradation of detection properties with an extreme and following improvement depending on detector material properties. SI GaAs detector still retains its working capabilities even after very high doses applied, up to 1 MGy.

  17. Experimental study of the response of CZT and CdTe detectors of various thicknesses in strong magnetic field

    NASA Astrophysics Data System (ADS)

    Tan, J. W.; Cai, L.; Meng, L. J.

    2011-10-01

    In this paper, we used a combined experimental and Monte Carlo simulation approach to investigate the detailed charge collection process within thick CdTe/CZT detectors operated inside a strong magnetic field. As one of the key objectives, we quantitatively assessed the effect of the Lorenz force on the migration of charge carriers inside the detector bulk. This information would allow an accurate modeling of the detector's response to gamma ray interactions and therefore help to compensate for the event-positioning error induced by the strong magnetic field. In this study, a pixilated ERPC detector with 350 μm square pixels was set on a non-magnetic gantry and operated inside a 3 T Siemens MRI scanner. Multiple studies, with similar geometries, were performed using the same detector setup with and without the presence of the magnetic field to investigate the effect on the charge collection behavior from the strong magnetic field. The experimental results were used to validate the Monte Carlo simulation package that models both photon transportation and charge collection process inside the detector.

  18. Radiation hardness and precision timing study of silicon detectors for the CMS High Granularity Calorimeter (HGC)

    NASA Astrophysics Data System (ADS)

    Currás, Esteban; Fernández, Marcos; Gallrapp, Christian; Gray, Lindsey; Mannelli, Marcello; Meridiani, Paolo; Moll, Michael; Nourbakhsh, Shervin; Scharf, Christian; Silva, Pedro; Steinbrueck, Georg; Fatis, Tommaso Tabarelli de; Vila, Iván

    2017-02-01

    The high luminosity upgraded LHC or Phase-II is expected to increase the instantaneous luminosity by a factor of 10 beyond the LHC's design value, expecting to deliver 250 fb-1 per year for a further 10 years of operation. Under these conditions the performance degradation due to integrated radiation dose will need to be addressed. The CMS collaboration is planning to upgrade the forward calorimeters. The replacement is called the High Granularity Calorimeter (HGC) and it will be realized as a sampling calorimeter with layers of silicon detectors interleaved. The sensors will be realized as pad detectors with sizes of less that ∼1.0 cm2 and an active thickness between 100 and 300 μm depending on the position, respectively, the expected radiation levels. For an integrated luminosity of 3000 fb-1, the electromagnetic calorimetry will sustain integrated doses of 1.5 MGy (150 Mrads) and neutron fluences up to 1016 neq/cm2. A radiation tolerance study after neutron irradiation of 300, 200, and 100 μm n-on-p and p-on-n silicon pads irradiated to fluences up to 1.6×1016 neq/cm2 is presented. The properties of these diodes studied before and after irradiation were leakage current, capacitance, charge collection efficiency, annealing effects and timing capability. The results of these measurements validate these sensors as candidates for the HGC system.

  19. A study of commercially-available polyethylene terephthalate (PET) and polycarbonate as nuclear track detector materials

    NASA Astrophysics Data System (ADS)

    Espinosa, G.; Golzarri, J. I.; Vazquez-Lopez, C.; Trejo, R.; Lopez, K.; Rickards, J.

    2014-07-01

    In the study of the sensitivity of materials to be used as nuclear track detectors, it was found that commercial polyethylene terephthalate (PET) from Ciel® water bottles, commercial roof cover polycarbonate, and recycled packaging strips (recycled PET), can be used as nuclear track detectors. These three commercial materials present nuclear tracks when bombarded by 2.27 MeV nitrogen ions produced in a Pelletron particle accelerator, and by fission fragments from a 252Cf source (79.4 and 103.8 MeV), after a chemical etching with a 6.25M KOH solution, or with a 6.25M KOH solution with 20% methanol, both solutions at 60±1°C. As an example, the nitrogen ions deposit approximately 1 keV/nm in the form of ionization and excitation at the surface of PET, as calculated using the SRIM code. The fission fragments deposit up to 9 keV/nm at the surface, in both cases generating sufficient free radicals to initiate the track formation process. However, 5 MeV alpha particles, typical of radon (222Rn) emissions, deposit only 0.12 keV/nm, do not present tracks after the chemical etching process. This valuable information could be very useful for further studies of new materials in nuclear track methodology.

  20. Comparison of a pixelated semiconductor detector and a non-pixelated scintillation detector in pinhole SPECT system for small animal study.

    PubMed

    Iida, Hirokazu; Ogawa, Koichi

    2011-02-01

    The aim of this work was to evaluate a pixelated semiconductor detector and non-pixelated scintillation detector in a pinhole SPECT system for small animal imaging. We assumed two pixelated CdTe semiconductor detectors (a monolithic type and a modular type) and two non-pixelated NaI(Tl) scintillation detectors (a conventional type and a large detector field type). For the monolithic semiconductor detector we assumed that the size of a pixel was 1.0 × 1.0 mm², the thickness 1 mm, and an effective detector field 128 × 128 mm². For the modular-type semiconductor detector we assumed that the size of a pixel was 2.5 × 2.5 mm², the thickness 5 mm, and an effective detector field 320 × 320 mm². For the two scintillation detectors we assumed that the size of a pixel was 1.4 × 1.4 mm² and the intrinsic spatial resolution 4.0 mm FWHM, and the thickness 9 mm. For the conventional scintillation detector we assumed that the effective detector field was 179.2 × 179.2 mm², and for the large field scintillation detector 358.2 × 358.2 mm² and the magnification factor two. In the simulation we used a pinhole collimator with a pinhole size of 0.3 mm. We reconstructed SPECT images of hot-rod and cold-channel phantoms with projection data calculated with a Monte Carlo method assuming a fixed data acquisition time, and evaluated the image quality with respect to contrast and spatial resolution. In addition, we calculated the scatter fraction to compare the amount of scattered photons between the pixelated and non-pixelated detectors. The image quality of the modular-type pixelated detector was similar to that of the non-pixelated detector operated with a twofold magnified data acquisition. The scattered photons and the parallax effect in the pixelated detector were small and similar to those in the non-pixelated detector. The performance of a modular-type pixelated semiconductor detector was almost the same as that of a non-pixelated scintillation detector with a magnified

  1. Position Ring System using Anger Type Detectors

    SciTech Connect

    Joel S. Karp, principal investigator

    2004-12-14

    The overall objective of our project was to develop PET scanners and imaging techniques that achieve high performance and excellent image quality. Our approach was based upon 3-D imaging (no septa) with position-sensitive Anger-logic detectors, whereby the encoding ratio of resolution elements to number of photo-multiplier tube channels is very high. This design led to a series of PET systems that emphasized cost-effectiveness and practicality in a clinical environment.

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

  3. Simulation study of light transport in laser-processed LYSO:Ce detectors with single-side readout.

    PubMed

    Blackberg, Lisa; El Fakhri, Georges; Sabet, Hamid

    2017-09-20

    A tightly focused pulsed laser beam can locally modify the crystal structure inside the bulk of a scintillator. The result is incorporation of so-called optical barriers with a refractive index different from that of the crystal bulk, that can be used to redirect the scintillation light and control the light spread in the detector. We here systematically study the scintillation light transport in detectors fabricated using the Laser Induced Optical Barrier technique, and objectively compare their potential performance characteristics with those of the two mainstream detector types: monolithic and mechanically pixelated arrays. Among countless optical barrier patterns, we explore barriers arranged in a pixel-like pattern extending all-the-way or half-way through a 20 mm thick LYSO:Ce crystal. We analyze the performance of the detectors coupled to MPPC arrays, in terms of light response functions, flood maps, line profiles, and light collection efficiency. Our results show that laser-processed detectors with both barrier patterns constitute a new detector category with a behavior between that of the two standard detector types. Results show that when the barrier-crystal interface is smooth, no DOI information can be obtained regardless of barrier refractive index (RI). However, with a rough barrier-crystal interface we can extract multiple levels of DOI. Lower barrier RI results in larger light confinement, leading to better transverse resolution. Furthermore we see that the laser-processed crystals have the potential to increase the light collection efficiency, which could lead to improved energy resolution and potentially better timing resolution due to higher signals. For a laser-processed detector with smooth barrier-crystal interfaces the light collection efficiency is simulated to >42%, and for rough interfaces >73%. The corresponding numbers for a monolithic crystal is 39% with polished surfaces, and 71% with rough surfaces, and for a mechanically

  4. Monte Carlo simulation of scintillation photons for the design of a high-resolution SPECT detector dedicated to human brain.

    PubMed

    Hirano, Yoshiyuki; Zeniya, Tsutomu; Iida, Hidehiro

    2012-04-01

    In a typical single photon emission computed tomography (SPECT) system, intrinsic spatial resolution depends on the accuracy of the identification of an interacting point, which is dominated by propagation of the scintillation photons in the detector block. This study was intended to establish a Monte Carlo simulation-based evaluation tool taking into account the propagation of scintillation photons to estimate the intrinsic spatial and energy resolutions of the position-sensitive scintillator block in a SPECT detector. We employed Geant4 Monte Carlo simulation library which incorporated the optical photon processes for two different designs of the position-sensitive scintillator blocks. The validation of the simulation code was performed for a monolithic NaI(Tl) scintillator (251 × 147 × 6.4 mm(3)) coupled to 15 flat-panel type multi-anode photo multiplier tubes (PMT) (H8500: Hamamatsu) and results were compared with those obtained experimentally. The code was then applied to a LaBr(3)(Ce) scintillator of 120 mm square with varied thicknesses for designing high-resolution detector. The simulation resulted in 2.6 mm full width at half maximum (FWHM) of spatial resolution and 9.0% FWHM of energy resolution for the NaI(Tl)-based detector, which were in a good agreement of the experimental results, i.e., 2.7 mm and 10%, respectively. These findings suggest that Geant4 simulation including optical photon processes enables to predict the spatial and energy resolutions of a SPECT detector block accurately. The simulation also demonstrated that 2 mm spatial resolution can be obtained for a 6 mm thickness of the LaBr(3)(Ce), which is a significant improvement in performance as compared to existing gamma camera system that employs the scintillation detector fitted with PMTs. The Monte Carlo simulation-based evaluation tool was established to estimate the intrinsic spatial and energy resolutions of SPECT detector with position sensitive PMTs. This simulation may

  5. Study of bulk damage in high resistivity silicon detectors irradiated by high dose of {sup 60}Co {gamma}-radiation

    SciTech Connect

    Li, Z.; Li, C.J.

    1996-04-01

    High dose (> 200 Mrad) {gamma}-radiation induced displacement damage (or bulk damage) in high resistivity (6--10 k{Omega}-cm) silicon detectors has been studied. It has been found that detector bulk leakage current increases with {gamma} dose at a rate of 3.3 {times} 10{sup {minus}7} A/cm{sup 3}/Mrad. This introduction rate of bulk leakage current makes the introduction of generation centers by 210 Mrad of {gamma}-radiation comparable to that by 1 {times} 10{sup 12} n/cm{sup 2} of neutron radiation. Significant carrier removal (or donor removal), about 100%, was found in detectors irradiated to 215 Mrad. Space charge sign inversion (SCSI) (or type inversion) was observed in detectors irradiated to {ge} 215 Mrad using transient current technique (TCT). As many as seven deep levels have been observed by current deep level transient spectroscopy (I-DLTS). There was little or no annealing (or reverse annealing) for detectors irradiated to 215 Mrad. Some annealing for detectors irradiated to 500 Mrad have been observed.

  6. Inverse kinematics (p, n) reactions studies using the WINDS slow neutron detector and the SAMURAI spectrometer

    NASA Astrophysics Data System (ADS)

    Yasuda, J.; Sasano, M.; Zegers, R. G. T.; Baba, H.; Chao, W.; Dozono, M.; Fukuda, N.; Inabe, N.; Isobe, T.; Jhang, G.; Kameda, D.; Kubo, T.; Kurata-Nishimura, M.; Milman, E.; Motobayashi, T.; Otsu, H.; Panin, V.; Powell, W.; Sakai, H.; Sako, M.; Sato, H.; Shimizu, Y.; Stuhl, L.; Suzuki, H.; Tangwancharoen, S.; Takeda, H.; Uesaka, T.; Yoneda, K.; Zenihiro, J.; Kobayashi, T.; Sumikama, T.; Tako, T.; Nakamura, T.; Kondo, Y.; Togano, Y.; Shikata, M.; Tsubota, J.; Yako, K.; Shimoura, S.; Ota, S.; Kawase, S.; Kubota, Y.; Takaki, M.; Michimasa, S.; Kisamori, K.; Lee, C. S.; Tokieda, H.; Kobayashi, M.; Koyama, S.; Kobayashi, N.; Wakasa, T.; Sakaguchi, S.; Krasznahorkay, A.; Murakami, T.; Nakatsuka, N.; Kaneko, M.; Matsuda, Y.; Mucher, D.; Reichert, S.; Bazin, D.; Lee, J. W.

    2016-06-01

    We have combined the low-energy neutron detector WINDS (Wide-angle Inverse-kinematics Neutron Detectors for SHARAQ) and the SAMURAI spectrometer at RIKEN Nishina Center RI Beam Factory (RIBF) in order to perform (p, n) reactions in inverse kinematics for unstable nuclei in the mass region around A ∼ 100 . In this setup, WINDS is used for detecting recoil neutrons and the SAMURAI spectrometer is used for tagging decay channel of heavy residue. The first experiment by using the setup was performed to study Gamow-Teller transitions from 132Sn in April 2014. The atomic number Z and mass-to-charge ratio A / Q of the beam residues were determined from the measurements of time of flight, magnetic rigidity and energy loss. The obtained A / Q and Z resolutions were σA/Q = 0.14 % and σZ = 0.22 , respectively. Furthermore, owing to the large momentum acceptance (50 %) of SAMURAI, the beam residues associated with the γ , 1n and 2n decay channel were measured in the same magnetic field setting. The kinematic loci of the measured recoil neutron energy and laboratory angle are clearly seen. It shows that the excitation energy up to about 20 MeV can be reconstructed.

  7. Photoelectronic studies of an asymmetric step quantum-well middle wavelength infrared detector

    NASA Astrophysics Data System (ADS)

    Wu, Wen-Gang; Chen, Zhibin

    2001-10-01

    Photoelectronic characteristics of the fabricated InxGa1-xAs/AlyGa1- yAs/AlzGa1-zAs asymmetric step quantum-well middle wavelength (3 to approximately 5 micrometers ) infrared detectors are studied. The components display photovoltaic-type photocurrent response as well as the bias- controlled modulation of the peak wavelength of the main response, which is ascribed to the Stark shifts of the intersubband transitions from the local ground states to the extended first excited states in the quantum wells, at the 3 to approximately 5.3 micrometers infrared atmospheric transmission window. The blackbody detectivity (Dbb*) of the detectors reaches to about 1.0 X 1010 cm(DOT)Hz1/2/W at 77 K under bias of +/- 7 V. By expanding the electron wave function in terms of normalized plane wave basis withn the framwork of the effective-mass envelope-function theory, the linear Stark effects of the intersubband tansitions between the ground and first excited states in the asymmetric step well are calculated. The obtained results agree well with the corresponding experimental measurements.

  8. Controllable passive detectors for study of the radiation environment in space and the atmosphere.

    PubMed

    Akopova, A B

    1998-01-01

    We propose to study the radiation environment on board different flight vehicles: cosmos-type satellites, orbital stations, Space Shuttles and civil (sonic and supersonic) aircraft. These investigations will be carried out with single type of passive detector, namely, nuclear photoemulsions (NPE) with adjustable threshold of particle detection within broad range of linear energy transfer (LET) that is done by means of the technique of selective development of NPE exposed in space. These investigations will allow, one to determine: integral spectra of LET of charged particles of cosmic ray (CR) over a wide range from 2.0 to 5 x 10(4) MeV/cm in biological tissue; differential energy spectra of fast neutrons (1-20 MeV); estimation of absorbed and equivalent doses from charged and neutral component CR; charge and energy spectra of low energy nuclei (E < or = 100 MeV) with Z > or = 2 having in view the extreme hazard radiation to biological objects and microelectronic schemes taken on board inside and outside of these different flight vehicles with exposures from several days to several months. The investigation of radiation environment on board the airplanes depending on the flight parameters will be conducted using emulsions of different sensitivity without any controlling of threshold sensitivity (Akopova et al., 1996). The proposed detector can be used in the joint experiments on the new International Cosmic Station "Alpha".

  9. A study of muon neutrino disappearance in the MINOS detectors and the NuMI beam

    SciTech Connect

    Ling, Jiajie

    2010-01-01

    There is now substantial evidence that the proper description of neutrino involves two representations related by the 3 x 3 PMNS matrix characterized by either distinct mass or flavor. The parameters of this mixing matrix, three angles and a phase, as well as the mass differences between the three mass eigenstates must be determined experimentally. The Main Injector Neutrino Oscillation Search experiment is designed to study the flavor composition of a beam of muon neutrinos as it travels between the Near Detector at Fermi National Accelerator Laboratory at 1 km from the target, and the Far Detector in the Soudan iron mine in Minnesota at 735 km from the target. From the comparison of reconstructed neutrino energy spectra at the near and far location, precise measurements of neutrino oscillation parameters from muon neutrino disappearance and electron neutrino appearance are expected. It is very important to know the neutrino flux coming from the source in order to achieve the main goal of the MINOS experiment: precise measurements of the atmospheric mass splitting |Δm232|, sin2 θ23. The goal of my thesis is to accurately predict the neutrino flux for the MINOS experiment and measure the neutrino mixing angle and atmospheric mass splitting.

  10. Studying B-Tagging Performance for new physics searches with the CMS Detector at the LHC

    NASA Astrophysics Data System (ADS)

    Last, David; CMS Collaboration

    2017-01-01

    Theoretical models for BSM physics often predict new particles that predominantly decay to b-quarks. The CMS (Compact Muon Solenoid) detector at CERN is one of two general purpose detectors collecting data from the LHC (Large Hadron Collider). A subset of the data, known as ``Scouting'' is collected with lower trigger thresholds than the nominal data acquisition paths, which allows searches for new physics with final state jets in lower mass region. Examples include searches for resonances in dijets, three-jets and paired dijets. The b-tagged version of all these low-mass analyses will benefit from an independent understanding of the b-tagging performance of jets in the Scouting dataset. In this study, we examine the purity and efficiency of the CSV (Combined Secondary Vertex) variable in the Scouting dataset to identify a b-jet. We isolate a sample of jet-triplets rich in hadronic top quark decays without any requirement on the b-tagging within the triplet, and examine the CSV value of the b-jet from top decay. This project has been supported by funding from National Science Foundation grants PHY-1263280 and PHY-1560077.

  11. Oxygen ingress study of 3D printed gaseous radiation detector enclosures

    SciTech Connect

    Steer, Christopher A.; Durose, Aaron

    2015-07-01

    As part of our ongoing studies into the potential application of 3D printing techniques to gaseous radiation detectors, we have studied the ability of 3D printed enclosures to resist environmental oxygen ingress. A set of cuboid and hexagonal prism shaped enclosures with wall thicknesses of 4 mm, 6 mm, 8 mm and 10 mm were designed and printed in nylon using a EOSINT P 730 Selective Laser Sintering 3D printer system These test enclosures provide a comparison of different environmental gas ingress for different 3D printing techniques. The rate of change of oxygen concentration was found to be linear, decreasing as the wall thickness increases. It was also found that the hexagonal prism geometry produced a lower rate of change of oxygen concentration compared with the cuboid shaped enclosures. Possible reasons as to why these results were obtained are discussed The implications for the this study for deployable systems are also discussed (authors)

  12. Cone-beam CT breast imaging with a flat panel detector: a simulation study

    NASA Astrophysics Data System (ADS)

    Chen, Lingyun; Shaw, Chris C.; Tu, Shu-Ju; Altunbas, Mustafa C.; Wang, Tianpeng; Lai, Chao-Jen; Liu, Xinming; Kappadath, S. C.

    2005-04-01

    This paper investigates the feasibility of using a flat panel based cone-beam computer tomography (CT) system for 3-D breast imaging with computer simulation and imaging experiments. In our simulation study, 3-D phantoms were analytically modeled to simulate a breast loosely compressed into cylindrical shape with embedded soft tissue masses and calcifications. Attenuation coefficients were estimated to represent various types of breast tissue, soft tissue masses and calcifications to generate realistic image signal and contrast. Projection images were computed to incorporate x-ray attenuation, geometric magnification, x-ray detection, detector blurring, image pixelization and digitization. Based on the two-views mammography comparable dose level on the central axis of the phantom (also the rotation axis), x-ray kVp/filtration, transmittance through the phantom, detected quantum efficiency (DQE), exposure level, and imaging geometry, the photon fluence was estimated and used to estimate the phantom noise level on a pixel-by-pixel basis. This estimated noise level was then used with the random number generator to produce and add a fluctuation component to the noiseless transmitted image signal. The noise carrying projection images were then convolved with a Gaussian-like kernel, computed from measured 1-D line spread function (LSF) to simulated detector blurring. Additional 2-D Gaussian-like kernel is designed to suppress the noise fluctuation that inherently originates from projection images so that the reconstructed image detectability of low contrast masses phantom can be improved. Image reconstruction was performed using the Feldkamp algorithm. All simulations were performed on a 24 PC (2.4 GHz Dual-Xeon CPU) cluster with MPI parallel programming. With 600 mrads mean glandular dose (MGD) at the phantom center, soft tissue masses as small as 1 mm in diameter can be detected in a 10 cm diameter 50% glandular 50% adipose or fatter breast tissue, and 2 mm or larger

  13. Study of Transport Behavior and Conversion Efficiency in Pillar Structured Neutron Detectors

    SciTech Connect

    Nikolic, R

    2007-04-26

    Room temperature, high efficiency and scalable radiation detectors can be realized by manipulating materials at the micro scale. With micro-semiconductor-pillars, we will advance the thermal neutron detection efficiency of semiconductor detectors to over 70% with 50 mm in detector thickness. New material science, new transport behavior, neutron to alpha conversion dynamics and their relationship with neutron detection will be discovered with the proposed structures.

  14. Study of a high-resolution PET system using a Silicon detector probe

    NASA Astrophysics Data System (ADS)

    Brzeziński, K.; Oliver, J. F.; Gillam, J.; Rafecas, M.

    2014-10-01

    A high-resolution silicon detector probe, in coincidence with a conventional PET scanner, is expected to provide images of higher quality than those achievable using the scanner alone. Spatial resolution should improve due to the finer pixelization of the probe detector, while increased sensitivity in the probe vicinity is expected to decrease noise. A PET-probe prototype is being developed utilizing this principle. The system includes a probe consisting of ten layers of silicon detectors, each a 80 × 52 array of 1 × 1 × 1 mm3 pixels, to be operated in coincidence with a modern clinical PET scanner. Detailed simulation studies of this system have been performed to assess the effect of the additional probe information on the quality of the reconstructed images. A grid of point sources was simulated to study the contribution of the probe to the system resolution at different locations over the field of view (FOV). A resolution phantom was used to demonstrate the effect on image resolution for two probe positions. A homogeneous source distribution with hot and cold regions was used to demonstrate that the localized improvement in resolution does not come at the expense of the overall quality of the image. Since the improvement is constrained to an area close to the probe, breast imaging is proposed as a potential application for the novel geometry. In this sense, a simplified breast phantom, adjacent to heart and torso compartments, was simulated and the effect of the probe on lesion detectability, through measurements of the local contrast recovery coefficient-to-noise ratio (CNR), was observed. The list-mode ML-EM algorithm was used for image reconstruction in all cases. As expected, the point spread function of the PET-probe system was found to be non-isotropic and vary with position, offering improvement in specific regions. Increase in resolution, of factors of up to 2, was observed in the region close to the probe. Images of the resolution phantom showed

  15. DETECTORS AND EXPERIMENTAL METHODS Studies of dE/dx measurements with the BESIII

    NASA Astrophysics Data System (ADS)

    Cao, Xue-Xiang; Li, Wei-Dong; Roy, A. Briere; Liu, Chun-Lei; Mao, Ze-Pu; Chen, Shen-Jian; Deng, Zi-Yan; He, Kang-Lin; Huang, Xing-Tao; Huang, Bin; Huang, Yan-Ping; Jia, Lu-Kui; Ji, Xiao-Bin; Li, Xiu-Rong; Liu, Chun-Yan; Liu, Huai-Min; Ma, Qiu-Mei; Ma, Xiang; Qiu, Jin-Fa; Wang, Da-Yong; Wu, Ling-Hui; Wu, Zhi; Yuan, Ye; Zhang, Xue-Yao; Zhao, Chuan; Zhang, Yao; Zou, Jia-Heng

    2010-12-01

    The Beijing Spectrometer III (BESIII) is a general-purpose detector used for the study of τ-charm physics at the Beijing Electron-Positron Collider II (BEPCII). This paper presents our studies of the dE/dx measurement in the drift chamber of BESIII, which is important for the identification of charged particles. Corrections applied to the dE/dx measurement in data reconstruction are discussed. After our current dE/dx calibration, a resolution of about 6% has been obtained for minimum ionization particles, and a 3σ K/π separation is obtained for momenta up to 760 MeV/c. These results meet the design goals of the BESIII drift chamber.

  16. Liquid-Xe detector for contraband detection

    NASA Astrophysics Data System (ADS)

    Vartsky, D.; Israelashvili, I.; Cortesi, M.; Arazi, L.; Coimbra, A. E.; Moleri, L.; Erdal, E.; Bar, D.; Rappaport, M.; Shchemelinin, S.; Caspi, E. N.; Aviv, O.; Breskin, A.

    2016-07-01

    We describe progress made with a liquid-Xe (LXe) detector coupled to a gaseous photomultiplier (GPM), for combined imaging and spectroscopy of fast neutrons and gamma-rays in the MeV range. The purpose of this detector is to enable the detection of hidden explosives and fissile materials in cargo and containers. The expected position resolution is about 2 m and 3.5 mm for fast neutrons and gamma-rays, respectively. Experimental results obtained using an 241Am source yielded energy and time resolutions of 11% and 1.2 ns RMS, respectively. Initial results obtained with the position-sensitive GPM are presented.

  17. RADIATION DETECTOR

    DOEpatents

    Wilson, H.N.; Glass, F.M.

    1960-05-10

    A radiation detector of the type is described wherein a condenser is directly connected to the electrodes for the purpose of performing the dual function of a guard ring and to provide capacitance coupling for resetting the detector system.

  18. High precision thermal neutron detectors

    SciTech Connect

    Radeka, V.; Schaknowski, N.A.; Smith, G.C.; Yu, B.

    1994-12-31

    Two-dimensional position sensitive detectors are indispensable in neutron diffraction experiments for determination of molecular and crystal structures in biology, solid-state physics and polymer chemistry. Some performance characteristics of these detectors are elementary and obvious, such as the position resolution, number of resolution elements, neutron detection efficiency, counting rate and sensitivity to gamma-ray background. High performance detectors are distinguished by more subtle characteristics such as the stability of the response (efficiency) versus position, stability of the recorded neutron positions, dynamic range, blooming or halo effects. While relatively few of them are needed around the world, these high performance devices are sophisticated and fairly complex, their development requires very specialized efforts. In this context, we describe here a program of detector development, based on {sup 3}He filled proportional chambers, which has been underway for some years at the Brookhaven National Laboratory. Fundamental approaches and practical considerations are outlined that have resulted in a series of high performance detectors with the best known position resolution, position stability, uniformity of response and reliability over time, for devices of this type.

  19. Acoustic studies for alpha background rejection in dark matter bubble chamber detectors

    SciTech Connect

    Bou-Cabo, M.; Felis, I.; Ardid, M.; Collaboration: COUPP Collaboration

    2013-08-08

    COUPP (Chicagoland Observatory for Underground Particle Physics) is an experiment with bubble chambers able to detect dark matter directly either with Spin-Dependent or with Spin-Independent interactions. The target material is a superheated liquid (usually CF3I) that can be bubble nucleated due to nuclear recoils produced by elastic collisions of dark matter particles. The bubble growth inside the chamber is accompanied with an acoustic signature. The acoustic technique has been successfully used to have a good alpha discrimination (about 99%). In this paper, we present different studies and results related with the characterization of the acoustic properties of the detector and the different phenomena involved in the acoustic measurements of the bubble growth, such as sound generation, sound transmission and optimization of piezoelectric transducers.

  20. Experimental study of high sensitivity infrared spectrometer with waveguide-based up-conversion detector(1).

    PubMed

    Ma, Lijun; Slattery, Oliver; Tang, Xiao

    2009-08-03

    We have developed an up-conversion spectrometer for signals at single photon levels near the infrared region based on a tunable up-conversion detector that uses a periodically poled lithium niobate waveguide as the conversion medium. We also experimentally studied its characteristics including sensitivity, dark count rate, spectral scan speed, signal transfer function of the waveguide, and polarization sensitivity. The overall single photon detection efficiency of the up-conversion spectrometer is about 32%. With its ultra high sensitivity the spectrometer can measure spectra for signals at a level as low as -126 dBm. We have demonstrated the spectrometers high sensitivity by measuring the spectrum of a greatly attenuated multimode emission from a laser diode at the 1310 nm band.

  1. Experimental and numerical study of thin fragments protection for radiographic detectors

    NASA Astrophysics Data System (ADS)

    Counilh, D.; Gillot, F.; Adolf, L.-M.; Silvin, P.; Rambert, N.; Hebert, D.; Bertron, I.; Bozier, O.

    2017-01-01

    To perform a non-intrusive measurement on a pyrotechnic setup, we usually use radiography. But, the X-ray generator and the detectors of the radiographic chain must be protected against the blast and. We carried out an experimental campaign to test the performances of various shielding. Representative cylindrical projectiles with various masses (from 20g to 40g) and aspect ratios (length to diameter ratio from 0.1 to 1) were launched with a gas gun at different initial velocities (from 1500m/s up to 2000m/s). Multiple shield configurations, based on assemblies of steel, aluminum and B4C plates were tested. The experimental results were combined with numerical studies to demonstrate the capabilities of the shield to stop fragments.

  2. Study of the $\\beta $ Decay of Fission Products with the DTAS Detector

    SciTech Connect

    Guadilla, V.; Algora, A.; Tain, J. L.; Agramunt, J.; Aysto, J.; Briz, J. A.; Cucoanes, A.; Eronen, T.; Estienne, M.; Fallot, M.; Fraile, L. M.; Ganioglu, E.; Gelletly, W.; Gorelov, D.; Hakala, J.; Jokinen, A.; Jordan, D.; Kankainen, A.; Kolhinen, V.; Koponen, J.; Lebois, M.; Martinez, T.; Monserrate, M.; Montaner-Piza, A.; Moore, I.; Nacher, E.; Orrigo, S. E. A.; Penttila, H.; Pohjalainen, I.; Porta, A.; Reinikainen, J.; Reponen, M.; Rinta-Antila, S.; Rubio, B.; Rytkonen, K.; Shiba, T.; Sonnenschein, V.; Sonzogni, A. A.; Valencia, E.; Vedia, V.; Voss, A.; Wilson, J. N.; Zakari-Issoufou, A. -A.

    2017-01-01

    Total Absorption Spectroscopy measurements of the β decay of 103Mo and 103Tc, important contributors to the decay heat summation calculation in reactors, are reported in this work. Furthermore, the analysis of the experiment, performed at IGISOL with the new DTAS detector, show new β intensity that was not detected in previous measurements with Ge detectors.

  3. Study of the $$\\beta $$ Decay of Fission Products with the DTAS Detector

    DOE PAGES

    Guadilla, V.; Algora, A.; Tain, J. L.; ...

    2017-01-01

    Total Absorption Spectroscopy measurements of the β decay of 103Mo and 103Tc, important contributors to the decay heat summation calculation in reactors, are reported in this work. Furthermore, the analysis of the experiment, performed at IGISOL with the new DTAS detector, show new β intensity that was not detected in previous measurements with Ge detectors.

  4. EMCCD-Based Detector for Time-Resolved X-Ray Diffraction and Scattering Studies of Biological Specimens

    SciTech Connect

    Nagarkar, Vivek V.; Singh, Bipin; Guo, Liang; Gore, David; Irving, Thomas C.

    2007-11-26

    Third generation synchrotron sources such as the Advanced Photon Source (APS), Argonne, IL, are outstanding tools for X-ray diffraction and scattering studies of non-crystalline biological materials. However, these studies are hindered by the lack of detectors that provide multiple frames of detailed structural information on the millisecond time scale at the required high spatial resolution, and large active areas. Here we report the development of a cost effective detector for time-resolved small angle X-ray scattering (SAXS) using a cooled, fiberoptically coupled electron multiplying CCD (EMCCD), whose internal gain is selectable in real-time. The performance of the detector was evaluated using a Gd{sub 2}O{sub 2}S:Tb scintillator and was compared to a current state-of-the-art SAXS detector developed at Brandeis University. We also report our first results on the fabrication of a novel, microcolumnar, ZnSe(Te) scintillator that has a promise to provide very high emission efficiency of over 100,000 photons/MeV, high spatial resolution in excess of 10 lp/mm, and a fast decay time with virtually absent afterglow. Development of this scintillator will complement the EMCCD design, permitting the advances of a high spatial and temporal resolution, large area detector for time resolved applications.

  5. Handy Compton camera using 3D position-sensitive scintillators coupled with large-area monolithic MPPC arrays

    NASA Astrophysics Data System (ADS)

    Kataoka, J.; Kishimoto, A.; Nishiyama, T.; Fujita, T.; Takeuchi, K.; Kato, T.; Nakamori, T.; Ohsuka, S.; Nakamura, S.; Hirayanagi, M.; Adachi, S.; Uchiyama, T.; Yamamoto, K.

    2013-12-01

    The release of radioactive isotopes (mainly 137Cs, 134Cs and 131I) from the crippled Fukushima Daiichi Nuclear Plant remains a serious problem in Japan. To help identify radiation hotspots and ensure effective decontamination operation, we are developing a novel Compton camera weighting only 1 kg and measuring just ∼10 cm2 in size. Despite its compactness, the camera realizes a wide 180° field of vision with a sensitivity about 50 times superior to other cameras being tested in Fukushima. We expect that a hotspot producing a 5 μSv/h dose at a distance of 3 m can be imaged every 10 s, with angular resolution better than 10° (FWHM). The 3D position-sensitive scintillators and thin monolithic MPPC arrays are the key technologies developed here. By measuring the pulse-height ratio of MPPC-arrays coupled at both ends of a Ce:GAGG scintillator block, the depth of interaction (DOI) is obtained for incident gamma rays as well as the usual 2D positions, with accuracy better than 2 mm. By using two identical 10 mm cubic Ce:GAGG scintillators as a scatterer and an absorber, we confirmed that the 3D configuration works well as a high-resolution gamma camera, and also works as spectrometer achieving typical energy resolution of 9.8% (FWHM) for 662 keV gamma rays. We present the current status of the prototype camera (weighting 1.5 kg and measuring 8.5×14×16 cm3 in size) being fabricated by Hamamatsu Photonics K.K. Although the camera still operates in non-DOI mode, angular resolution as high as 14° (FWHM) was achieved with an integration time of 30 s for the assumed hotspot described above.

  6. Simulating the growth of an charge cloud for a microchannel plate detector

    NASA Astrophysics Data System (ADS)

    Siwal, Davinder; Wiggins, Blake; Desouza, Romualdo

    2015-10-01

    Position sensitive microchannel plate (MCP) detectors have a variety of applications in the fields of astronomy, medical imaging, neutron imaging, and ion beam tracking. Recently, a novel approach has been implemented to detect the position of an incident particle. The charge cloud produced by the MCP induces a signal on a wire harp placed between the MCP and an anode. On qualitative grounds it is clear that in this detector the induced signal shape depends on the size of the electron cloud. A detailed study has therefore been performed to investigate the size of the charge cloud within the MCP and its growth as it propagates from the MCP to the anode. A simple model has been developed to calculate the impact of charge repulsion on the growth of the electron cloud. Both the details of the model and its predictions will be presented. Supported by the US DOE NNSA under Award No. DE-NA0002012.

  7. Gamma background studies for the XENON experiment using a High Purity Germanium Detector

    NASA Astrophysics Data System (ADS)

    Angle, Jesse Isaac

    The XENON Dark Matter Experiment, deployed at the Gran Sasso National Laboratory in Italy on March 2006, is a liquid noble gas detector designed to directly detect dark matter. The detector uses a dual-phase (gas/liquid) Xenon target to search for nuclear recoils associated with nucleus-WIMP interactions. Due to the high sensitivity needed in such an experiment, it is vital to not only reduce the background but to also understand the remaining background so as to aid in the understanding of the data as well as to facilitate upgrades beyond the early Research and Development phases. Many of the components of the XENON10 detector have been screened using a High Purity Germanium Detector known as the GATOR detector. Full analysis of the screening data requires Monte Carlo simulations of the GATOR detector and the sample. Results from this screening will be presented. Using the information obtained from the screening operation, Monte Carlo simulations of the XENON10 electron recoil background will be examined and compared to the actual detector data. The success of this simulation to data comparison indicates that we have a good understanding of the XENON10 gamma background and will be able to make more informed decisions regarding the next stage of detector development. This type of analysis has aided in the selection and design of many of the materials and components being incorporated into the new XENON100 detector, the next generation detector which will be capable of improving the limit set by XENON10 by at least an order of magnitude. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http:/ /www.uflib.ufl.edu/etd.html)

  8. Performance of an AGATA asymmetric detector

    SciTech Connect

    Boston, A. J.; Dimmock, M. R.; Unsworth, C.; Boston, H. C.; Cooper, R. J.; Grint, A. N.; Harkness, L. J.; Jones, M.; Nolan, P. J.; Oxley, D. C.; Slee, M.; Lazarus, I. H.; Simpson, J.

    2008-11-11

    Each major technical advance in gamma-ray detection devices has resulted in significant new insights into the structure of atomic nuclei. The next major step in gamma-ray spectroscopy involves achieving the goal of a 4{pi} ball of germanium detectors by using the technique of gamma-ray energy tracking in electrically segmented germanium crystals. The resulting spectrometer will have an unparalleled level of detection power for nuclear electromagnetic radiation. Collaborations have been established in Europe (AGATA)[1] and the USA (GRETA/GRETINA)[2] to build gamma-ray tracking spectrometers. This paper discusses the performance of the first AGATA (Advanced GAmma Tracking Array) asymmetric detector that has been tested at the University of Liverpool. The use of a fully digital data acquisition system has allowed detector charge pulse shapes from a selection of well defined photon interaction positions to be analysed, yielding important information on the position sensitivity of the detector.

  9. Gamma-ray imaging with germanium detectors

    NASA Astrophysics Data System (ADS)

    Mahoney, W. A.; Callas, J. L.; Ling, J. C.; Radocinski, R. G.; Skelton, R. T.; Varnell, L. S.; Wheaton, W. A.

    1993-01-01

    Externally segmented germanium detectors promise a breakthrough in gamma-ray imaging capabilities while retaining the superb energy resolution of germanium spectrometers. By combining existing position-sensitive detectors with an appropriate code aperture, two-dimensional imaging with 0.2-deg angular resolution becomes practical for a typical balloon experiment. Much finer resolutions are possible with larger separations between detectors and the coded aperture as would be applicable for space-based or lunar-based observatories. Two coaxial germanium detectors divided into five external segments have been fabricated and have undergone extensive performance evaluation and imaging testing in our laboratory. These tests together with detailed Monte Carlo modeling calculations have demonstrated the great promise of this sensor technology for future gamma-ray missions.

  10. Gamma-ray imaging with germanium detectors

    NASA Technical Reports Server (NTRS)

    Mahoney, W. A.; Callas, J. L.; Ling, J. C.; Radocinski, R. G.; Skelton, R. T.; Varnell, L. S.; Wheaton, W. A.

    1993-01-01

    Externally segmented germanium detectors promise a breakthrough in gamma-ray imaging capabilities while retaining the superb energy resolution of germanium spectrometers. By combining existing position-sensitive detectors with an appropriate code aperture, two-dimensional imaging with 0.2-deg angular resolution becomes practical for a typical balloon experiment. Much finer resolutions are possible with larger separations between detectors and the coded aperture as would be applicable for space-based or lunar-based observatories. Two coaxial germanium detectors divided into five external segments have been fabricated and have undergone extensive performance evaluation and imaging testing in our laboratory. These tests together with detailed Monte Carlo modeling calculations have demonstrated the great promise of this sensor technology for future gamma-ray missions.

  11. P-type silicon drift detectors

    SciTech Connect

    Walton, J.T.; Krieger, B.; Krofcheck, D.; O`Donnell, R.; Odyniec, G.; Partlan, M.D.; Wang, N.W.

    1995-06-01

    Preliminary results on 16 CM{sup 2}, position-sensitive silicon drift detectors, fabricated for the first time on p-type silicon substrates, are presented. The detectors were designed, fabricated, and tested recently at LBL and show interesting properties which make them attractive for use in future physics experiments. A pulse count rate of approximately 8 {times} l0{sup 6} s{sup {minus}1} is demonstrated by the p-type silicon drift detectors. This count rate estimate is derived by measuring simultaneous tracks produced by a laser and photolithographic mask collimator that generates double tracks separated by 50 {mu}m to 1200 {mu}m. A new method of using ion-implanted polysilicon to produce precise valued bias resistors on the silicon drift detectors is also discussed.

  12. Silicon radiation detectors: materials and applications

    SciTech Connect

    Walton, J.T.; Haller, E.E.

    1982-10-01

    Silicon nuclear radiation detectors are available today in a large variety of sizes and types. This profusion has been made possible by the ever increasing quality and diameter silicon single crystals, new processing technologies and techniques, and innovative detector design. The salient characteristics of the four basic detector groups, diffused junction, ion implanted, surface barrier, and lithium drift are reviewed along with the silicon crystal requirements. Results of crystal imperfections detected by lithium ion compensation are presented. Processing technologies and techniques are described. Two recent novel position-sensitive detector designs are discussed - one in high-energy particle track reconstruction and the other in x-ray angiography. The unique experimental results obtained with these devices are presented.

  13. A study of muon neutrino disappearance with the MINOS detectors and the NuMI neutrino beam

    SciTech Connect

    Marshall, John Stuart

    2008-06-01

    This thesis presents the results of an analysis of vμ disappearance with the MINOS experiment, which studies the neutrino beam produced by the NuMI facility at Fermi National Accelerator Laboratory. The rates and energy spectra of charged current vμ interactions are measured in two similar detectors, located at distances of 1 km and 735 km along the NuMI beamline. The Near Detector provides accurate measurements of the initial beam composition and energy, while the Far Detector is sensitive to the effects of neutrino oscillations. The analysis uses data collected between May 2005 and March 2007, corresponding to an exposure of 2.5 x 1020 protons on target. As part of the analysis, sophisticated software was developed to identify muon tracks in the detectors and to reconstruct muon kinematics. Events with reconstructed tracks were then analyzed using a multivariate technique to efficiently isolate a pure sample of charged current vμ events. An extrapolation method was also developed, which produces accurate predictions of the Far Detector neutrino energy spectrum, based on data collected at the Near Detector. Finally, several techniques to improve the sensitivity of an oscillation measurement were implemented, and a full study of the systematic uncertainties was performed. Extrapolating from observations at the Near Detector, 733 ± 29 Far Detector events were expected in the absence of oscillations, but only 563 events were observed. This deficit in event rate corresponds to a significance of 4.3 standard deviations. The deficit is energy dependent and clear distortion of the Far Detector energy spectrum is observed. A maximum likelihood analysis, which fully accounts for systematic uncertainties, is used to determine the allowed regions for the oscillation parameters and identifies the best fit values as Δm$2\\atop{32}$ = 2.29$+0.14\\atop{-0.14}$ x 10-3 eV2 and sin223

  14. Evaluating a new segmented germanium detector contact technology

    NASA Astrophysics Data System (ADS)

    Jackson, E. G.; Lister, C. J.; Chowdhury, P.; Hull, E.; Pehl, R.

    2012-10-01

    New technologies for making gamma ray detectors position sensitive have many applications in space science, medical imaging, homeland security, and in nuclear structure research. One promising approach uses high-purity germanium wafers with the planar surfaces segmented into orthogonal strip patterns forming a Double-Sided Strip Detector (DSSD). The combination of data from adjoining strips, or pixels, is physics-rich for Compton image formation and polarization studies. However, sensitivity to charge loss and various kinds of cross-talk [1] have limited the usefulness of first generation devices. We are investigating new contact technologies, developed by PhDs Co [2], based on amorphous-germanium and yttrium contacts RF sputter deposited to a thickness of ˜ 1000 å. New techniques allow both physical and photolithographic segmentation of the contacts with inter-strip gap widths of 0.25 mm. These modifications should improve all aspects of charge collection. The new detector technology employs the same material and fabrication technique for both the n- and p- contacts, thus removing artificial asymmetry in the data. Results from tests of cross-talk, charge collection, and scattering asymmetry will be presented and compared with older technologies. This mechanically cooled counter, NP-7, seems to represent a breakthrough.[4pt] [1] S. Gros et al., Nucl. Inst. Meth. A 602, 467 (2009).[0pt] [2] E. Hull et al Nucl Inst Meth A 626, 39 (2011)

  15. A comparative and combined study of EMIS and GPR detectors by the use of independent component analysis

    NASA Astrophysics Data System (ADS)

    Morgenstjerne, Axel; Karlsen, Brian; Larsen, Jan; Sorensen, Helge B. D.; Jakobsen, Kaj B.

    2005-06-01

    Independent Component Analysis (ICA) is applied to classify unexploded ordnance (UXO) on laboratory UXO test-field data, acquired by stand-off detection. The data are acquired by an Electromagnetic Induction Spectroscopy (EMIS) metal detector and a ground penetrating radar (GPR) detector. The metal detector is a GEM-3, which is a monostatic sensor measuring the response of the environment on a multi-frequency constant wave excitation field (300 Hz 25 kHz), and the GPR detector is a stepped-frequency GPR with a monostatic bow-tie antenna (500 MHz 2.5 GHz). For both sensors the in-phase and the quadrature responses are measured at each frequency. The test field is a box of soil where a wide range of UXOs are placed at selected positions. The position and movement of both of the detectors are controlled by a 2D-scanner. Thus the data are acquired at well-defined measurement points. The data are processed by the use of statistical signal processing based on ICA. An unsupervised method based on ICA to detect, discriminate, and classify the UXOs from clutter is suggested. The approach is studied on GPR and EMIS data, both separately and combined. The potential is an improved ability: to detect the UXOs, to evaluate the related characteristics, and to reduce the number of false alarms from harmless objects and clutter.

  16. Exploratory study of a novel low occupancy vertex detector architecture based on high precision timing for high luminosity particle colliders

    NASA Astrophysics Data System (ADS)

    Orel, Peter; Varner, Gary S.; Niknejadi, Pardis

    2017-06-01

    Vertex detectors provide space-time coordinates for the traversing charged particle decay products closest to the interaction point. Resolving these increasingly intense particle fluences at high luminosity particle colliders, such as SuperKEKB, is an ever growing challenge. This results in a non-negligible occupancy of the vertex detector using existing low material budget techniques. Consequently, new approaches are being studied that meet the vertexing requirements while lowering the occupancy. In this paper, we introduce a novel vertex detector architecture. Its design relies on an asynchronous digital pixel matrix in combination with a readout based on high precision time-of-flight measurement. Denoted the Timing Vertex Detector (TVD), it consists of a binary pixel array, a transmission line for signal collection, and a readout ASIC. The TVD aims to have a spatial resolution comparable to the existing Belle2 vertex detector. At the same time it offers a reduced occupancy by a factor of ten while decreasing the channel count by almost three orders of magnitude. Consequently, reducing the event size from about 1 MB/event to about 5.9 kB/event.

  17. Suspending test masses in terrestrial millihertz gravitational-wave detectors: a case study with a magnetic assisted torsion pendulum

    NASA Astrophysics Data System (ADS)

    Thrane, Eric; Anderson, Russell P.; Levin, Yuri; Turner, L. D.

    2017-05-01

    Current terrestrial gravitational-wave detectors operate at frequencies above 10 Hz. There is strong astrophysical motivation to construct low-frequency gravitational-wave detectors capable of observing 10 mHz-10 Hz signals. While space-based detectors provide one means of achieving this end, one may also consider terretrial detectors. However, there are numerous technological challenges. In particular, it is difficult to isolate test masses so that they are both seismically isolated and freely falling under the influence of gravity at millihertz frequencies. We investigate the challenges of low-frequency suspension in a hypothetical terrestrial detector. As a case study, we consider a magnetically assisted gravitational-wave pendulum intorsion (MAGPI) suspension design. We construct a noise budget to estimate some of the required specifications. In doing so, we identify what are likely to be a number of generic limiting noise sources for terrestrial millihertz gravitational-wave suspension systems (as well as some peculiar to the MAGPI design). We highlight significant experimental challenges in order to argue that the development of millihertz suspensions will be a daunting task. Any system that relies on magnets faces even greater challenges. Entirely mechanical designs such as Zöllner pendulums may provide the best path forward.

  18. Compton imager using room temperature silicon detectors

    NASA Astrophysics Data System (ADS)

    Kurfess, James D.; Novikova, Elena I.; Phlips, Bernard F.; Wulf, Eric A.

    2007-08-01

    We have been developing a multi-layer Compton Gamma Ray Imager using position-sensitive, intrinsic silicon detectors. Advantages of this approach include room temperature operation, reduced Doppler broadening, and use of conventional silicon fabrication technologies. We have obtained results on the imaging performance of a multi-layer instrument where each layer consists of a 2×2 array of double-sided strip detectors. Each detector is 63 mm×63 mm×2 mm thick and has 64 strips providing a strip pitch of approximately 0.9 mm. The detectors were fabricated by SINTEF ICT (Oslo Norway) from 100 mm diameter wafers. The use of large arrays of silicon detectors appears especially advantageous for applications that require excellent sensitivity, spectral resolution and imaging such as gamma ray astrophysics, detection of special nuclear materials, and medical imaging. The multiple Compton interactions (three or more) in the low-Z silicon enable the energy and direction of the incident gamma ray to be determined without full deposition of the incident gamma-ray energy in the detector. The performance of large volume instruments for various applications are presented, including an instrument under consideration for NASA's Advanced Compton Telescope (ACT) mission and applications to Homeland Security. Technology developments that could further extend the sensitivity and performance of silicon Compton Imagers are presented, including the use of low-energy (few hundred keV) electron tracking within novel silicon detectors and the potential for a wafer-bonding approach to produce thicker, position-sensitive silicon detectors with an associated reduction of required electronics and instrument cost.

  19. Study of rare decays of the b quark with the DELPHI detector at LEP

    NASA Astrophysics Data System (ADS)

    Battaglia, Marco

    The b quark is the heaviest fermion producing bound hadronic states. The study of their production and decays provides important data for the understanding of the processes responsible for the weak decays of fundamental fermions. In addition, due to the small value of the | Vcb| element, suppressed and rare b-->u and b-->s, d transitions are not completely obliterated by the CKM favoured b-->c decays. This makes B hadrons an ideal laboratory for the study of rare decay processes. The sensitivity of these decays to the Standard Model structure, through suppressions proportional to the square of the elements in the quark mixing matrix and through loops that may reveal contributions of new particles, opens a new window on precision tests of the Standard Model and also on possible new physics beyond it. The DELPHI detector, equipped with a precise silicon vertex tracker surrounding the beam interaction region and with Ping Imaging CHerenkov (RICH) detectors providing efficient hadron identification, at the LEP e +e- collider, is well suited for precise studies of B decays. This thesis presents the results of the analysis of the date, collected with DELPHI at centre-of-mass energies around the Z0 pole from 1990 to 1995 for the studies of rare decays of beauty hadrons. These studies have promoted the development of new techniques for the topological reconstruction of the B decay chain and for hadron identification based on the response of the RICH detectors. Rare decays of the b quarks have been studied in several decay processes. Tree level b-->u transitions have been studied mainly in the semileptonic b-->uln channel. A new technique that discriminate them from the favoured b-->c transitions based on the reconstructed mass of the hadronic system recoiling against the lepton has been developed and applied. Evidence for the decay has been obtained and its rate has been used to extract an accurate determination of the |Vub| element in the quark mixing matrix. Hadronic

  20. Cable tunnel fire experiment study based on linear optical fiber fire detectors

    NASA Astrophysics Data System (ADS)

    Fan, Dian; Ding, Hongjun

    2013-09-01

    Aiming at exiting linear temperature fire detection technology including temperature sensing cable, fiber Raman scattering, fiber Bragg grating, this paper establish an experimental platform in cable tunnel, set two different experimental scenes of the fire and record temperature variation and fire detector response time in the processing of fire simulation. Since a small amount of thermal radiation and no flame for the beginning of the small-scale fire, only directly contacting heat detectors can make alarm response and the rest of other non- contact detectors are unable to respond. In large-scale fire, the alarm response time of the fiber Raman temperature sensing fire detector and fiber Bragg grating temperature sensing fire detector is about 30 seconds, and depending on the thermocouples' record the temperature over the fire is less than 35° in first 60 seconds of large-scale fire, while the temperature rising is more than 5°/min within the range of +/- 3m. According to the technical characteristics of the three detectors, the engineering suitability of the typical linear heat detectors in cable tunnels early fire detection is analyzed, which provide technical support for the preparation of norms.