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Sample records for position-sensitive detector studies

  1. Position sensitive solid state detectors

    NASA Astrophysics Data System (ADS)

    Schnatterly, S. E.; Husk, D.

    1986-05-01

    Solid state detectors have been used for years as high quantum efficiency detectors for visible light. In this paper the use of PDA and CCD, solid state detectors, in the X-ray region will be discussed. In particular examples of data in the soft X-ray region are presented. Finally the use of phosphor coatings to enhance the sensitivity of solid state detectors is described.

  2. Mathematical modelling and study of the encoding readout scheme for position sensitive detectors

    NASA Astrophysics Data System (ADS)

    Yue, Xiaoguang; Zeng, Ming; Zeng, Zhi; Wang, Yi; Wang, Xuewu; Zhao, Ziran; Cheng, Jianping; Kang, Kejun

    2016-04-01

    Encoding readout methods based on different schemes have been successfully developed and tested with different types of position-sensitive detectors with strip-readout structures. However, how to construct an encoding scheme in a more general and systematic way is still under study. In this paper, we present a graph model for the encoding scheme. With this model, encoding schemes can be studied in a more systematic way. It is shown that by using an encoding readout method, a maximum of n (n - 1)/2 + 1 strips can be processed with n channels if n is odd, while a maximum of n (n - 2)/2 + 2 strips can be processed with n channels if n is even. Furthermore, based on the model, the encoding scheme construction problem can be translated into a problem in graph theory, the aim of which is to construct an Eulerian trail such that the length of the shortest subcycle is as long as possible. A more general approach to constructing the encoding scheme is found by solving the associated mathematical problem. In addition, an encoding scheme prototype has been constructed, and verified with MRPC detectors.

  3. 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.

  4. 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.

  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. 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.

  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. Large area position sensitive β-detector

    NASA Astrophysics Data System (ADS)

    Vaintraub, S.; Hass, M.; Edri, H.; Morali, N.; Segal, T.

    2015-03-01

    A new conceptual design of a large area electron detector, which is position and energy sensitive, was developed. This detector is designed for beta decay energies up to 4 MeV, but in principle can be re-designed for higher energies. The detector incorporates one large plastic scintillator and, in general, a limited number of photomultipliers (7 presently). The current setup was designed and constructed after an extensive Geant4 simulation study. By comparison of a single hit light distribution between the various photomultipliers to a pre-measured accurate position-response map, the anticipated position resolution is around 5 mm. The first benchmark experiments have been conducted in order to calibrate and confirm the position resolution of the detector. The new method, results of the first test experiments and comparison to simulations are presented.

  9. Position sensitivity in gallium arsenide radiation detectors

    SciTech Connect

    Harper, R.; Hilko, R.A.

    1994-12-31

    For several years, the authors have studied the electrical output of GaAs detectors in response to MeV protons. Beams from the Los Alamos National Laboratory`s tandem Van de Graaff, bunched into pulses of about 0.7-ns width, have been used to drive detectors into the current mode, and fast electronics have enabled characterization of the impulse response shapes and the absolute sensitivities. Recently, the authors extended this line of investigation to measure output-charge spectra in response to low-current beams, in which the count rate was low and pulses due to individual ionizing particles were analyzed. The first part of the work was the measurement of spectra of the output charge of the detectors when bombarded by a beam of MeV-energy protons, which was collimated to a diameter of 0.1 mm. The GaAs detector was mounted on a microadjustable stage just behind the collimator, so that the site of irradiation on the detector could be varied. Output pulses originating from the impacts of individual protons were preamplified with charge-sensitive Lecroy 2004 preamplifiers, shaped with Lecroy 2011 amplifiers, and analyzed with a Lecroy 3500 multichannel analyzer. The second part was the measurement of the time response of the detector to a 0.1 mm-collimated bunched proton beam. The proton bunch width was less than 1 ns, during which time many protons struck the detector, driving it into the current mode where individual proton impacts are unresolved. A possible detector design is suggested by the results. In the past, GaAs time response has been improved by doping or radiation damaging, which introduces traps. The tails can be eliminated, but at the cost of a factor of a thousand in main peak sensitivity. It now appears that by masking off the region of the detector near the negative electrode, the tails can be eliminated with only a factor of about ten loss in peak gain.

  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. A novel method for assessing position-sensitive detector performance

    SciTech Connect

    Clinthorne, N.H.; Rogers, W.L.; Shao, L.; Hero, A.O. III; Koral, K.F.

    1989-02-01

    A marked point process model of a position-sensitive detector is developed which includes the effects of detector efficiency, spatial response, energy response, and source statistics. The average mutual information between the incident distribution of ..gamma.. rays and the detector response is derived and used as a performance index for detector optimization. A brief example is presented which uses this figure-of-merit for optimization of light guide dimensions for a modular scintillation camera.

  12. Position sensitivity of the first SmartPET HPGe detector

    NASA Astrophysics Data System (ADS)

    Cooper, R. J.; Turk, G.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Mather, A. R.; Nolan, P. J.; Hall, C. J.; Lazarus, I.; Simpson, J.; Berry, A.; Beveridge, T.; Gillam, J.; Lewis, R. A.

    2007-04-01

    In this paper we discuss the Smart Positron Emission Tomography (PET) imaging system being developed by the University of Liverpool in conjunction with CCLRC Daresbury Laboratory. We describe the motivation for the development of a semiconductor-based PET system and the advantages it will offer over current tomographs. Details of the detectors and associated electronics are discussed and results of high precision scans are presented. Analysis of this scan data has facilitated full characterization of the detector response function and calibration of the three-dimensional position sensitivity. This work presents the analysis of the depth sensitivity of the detector.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26205266

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

    PubMed

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

    2015-01-01

    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. Pulsed neutron imaging using 2-dimensional position sensitive detectors

    NASA Astrophysics Data System (ADS)

    Kiyanagi, Y.; Kamiyama, T.; Kino, K.; Sato, H.; Sato, S.; Uno, S.

    2014-07-01

    2-dimensional position sensitive detectors are used for pulsed neutron imaging and at each pixel of the detector a time of flight spectrum is recorded. Therefore, a transmission spectrum through the object has wavelength dependent structure reflecting the neutron total cross section. For such measurements, the detectors are required to have ability to store neutron events as a function of the flight time as well as to have good spatial resolution. Furthermore, high counting rate is also required at the high intensity neutron sources like J-PARC neutron source in Japan. We have developed several types of detectors with different characteristics; two counting type detectors for high counting rate with coarse spatial resolution and one camera type detector for high spatial resolution. One of counting type detectors is a pixel type. The highest counting rate is about 28 MHz. Better spatial resolution is obtained by a GEM detector. Effective area is 10 × 10 cm2, pixel size is 0.8 mm. The maximum counting rate is 3.65 MHz. To get higher spatial resolution we are now developing the camera type detector system using a neutron image intensifier, which have image integration function as a function of time of flight. We have succeeded to obtain time dependent images in this camera system. By using these detectors we performed transmission measurements for obtaining the crystallographic information and elemental distribution images.

  16. Development of a novel position-sensitive microchannel plate detector

    NASA Astrophysics Data System (ADS)

    Wiggins, Blake; Siwal, Davinder; Desouza, Romualdo

    2015-10-01

    Position sensitive microchannel plate (MCP) detectors which measure the position of an incident electron, ion, or photon, are useful in imaging applications. Recently, a novel detector, which utilizes an induced approach to provide position sensitivity, has been developed. In the prototype detector, using only the zero-crossing point of the inherently bipolar signals, a position resolution of 466 μm (FWHM) has been achieved. Implementing a differential readout may improve on this resolution. To realize this differential approach, a better understanding of the dependence of the induced signal shape on the position of the electron cloud is required. To characterize the dependence of the induced signal shape on position a resistive anode (RA) has been incorporated into the detector. The RA will allow determination of the centroid of the electron cloud. Factors impacting the position resolution obtained with the RA will be discussed and the achieved position resolution of 157 μm (FWHM) will be presented. Supported by the US DOE NNSA under Award No. DE-NA0002012.

  17. 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.

  18. 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.

  19. High resolution, position sensitive detector for energetic particle beams

    NASA Astrophysics Data System (ADS)

    Marsh, E. P.; Strathman, M. D.; Reed, D. A.; Morse, D. H.; Pontau, A. E.; Odom, R. W.

    1993-05-01

    The performance and design of an imaging position sensitive, particle beam detector will be presented. The detector is minimally invasive, operates over a wide dynamic range (> 10 10), and exhibits high spatial resolution. The secondary electrons produced when a particle beam passes through a thin foil are imaged using stigmatic ion optics onto a two-dimensional imaging detector. Due to the low scattering cross section of the 6 nm carbon foil the detector is a minimal perturbation on the primary beam. A prototype detector with an image resolution of approximately 5 μm for a field of view of 1 mm has been reported [R.W. Odom, M.D. Strathman, S.E. Buttrill, Jr., and S.M. Bauman, Nucl. Instr. and Meth. B44 (1990) 465]. A higher resolution detector for imaging small beams (< 50 μm) with an image resolution of better than 0.5 μm has since been developed and its design is presented.

  20. 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.

  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. MRI compatibility of position-sensitive photomultiplier depth-of-interaction PET detectors modules for in-line multimodality preclinical studies

    NASA Astrophysics Data System (ADS)

    Vaquero, J. J.; Sánchez, J. J.; Udías, J. M.; Cal-González, J.; Desco, M.

    2013-02-01

    This work addresses the feasibility of a small-animal, in-line PET/MR system based on Position-Sensitive Photo Multiplier Tubes (PS-PMTs). To this end, we measured the effects of static magnetic fields on the PS-PMTs performance in order to explore the minimal tandem separation between the PET and MR subsystems to preserve their respective performances. We concluded that it is possible to achieve minimal degradation of the PET scanner performance (after a system recalibration) if the magnetic field strength influencing the PET detectors is less than 1 mT and if it is oriented perpendicularly to the longitudinal axis of the tube. Therefore, we predict that it will be possible to maintain the PET image quality if it is placed outside the 1 mT line.

  3. Position-sensitive detectors of the detector group at Jülich

    NASA Astrophysics Data System (ADS)

    Engels, R.; Clemens, U.; Kemmerling, G.; Nöldgen, H.; Schelten, J.

    2009-06-01

    The detector group of the Central Institute of Electronics at the Forschungszentrum Jülich GmbH was founded in 1968. First developments aimed at a detector system with a position-sensitive BF 3 proportional counter for small-angle neutron scattering, which was later used at a beamline of the research reactor FRJ2. At the end of the 1970s first measurements were carried out with photomultiplier (PM)-based detector systems linked with a LiI crystal from Harshaw. Based on this experience we started with the spectrum of position-sensitive neutron scintillation detectors, which have been developed and designed in our institute during the last three decades comprising several high-resolution linear and two-dimensional detectors. The general design of those detectors is based on a modified Anger principle using an array of PMs and a 1 mm 6Li glass scintillator. The sensitive detector area varies on the type of the PMs used and is related to the spatial resolution of the detector type. The neutron sensitivity at 1 Å is about 65% and the remaining gamma sensitivity is less than 10 -4 with a maximum count rate up to 500 kHz depending on the used detector system.

  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. Development of a Position Sensitive Heavy Ion Detector for Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Need, Emily; Blackmon, J. C.; Deibel, C. M.; Lai, J.; Lindhart, L. E.; Macon, K. T.; Matos, M.; Rasco, B. C.; Rogachev, G.; Wiedenhover, I.

    2012-10-01

    The Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN) is a charged-particle detector array used to study reactions with radioactive beams at FSU and the NSCL. One of the main goals is to improve our understanding of nuclear reactions important in stellar explosions. One important component of ANASEN is a heavy ion detector located downstream of the target that is used to identify the atomic number of heavy ions based upon their energy loss through the gas-filled chamber. We have developed a new version of this detector with major design changes to improve data collection and allow much greater selectivity for the reactions of interest. These changes include anodes based on custom printed circuit boards that provide position sensitivity, larger grids to provide greater acceptance, and a change in wire spacing on the grids to improve transmission. We will present the new design and results from initial tests.

  7. A multiplex readout method for position sensitive boron coated straw neutron detector

    NASA Astrophysics Data System (ADS)

    Yu, Hao; Gong, Hui; Li, Jianmin; Wang, Yongqiang; Wang, Xuewu; Li, Yuanjing; Kang, Kejun

    2015-10-01

    A 1 m×1 m boron coated straw neutron detector is expected to be used to build the small-angle neutron scattering (SANS) instrument of the Compact Pulsed Hadron Source (CPHS) in Tsinghua University. A multiplex readout method based on summing circuits in columns and rows is studied for this large area position sensitive detector. In this method, the outputs of charge sensitive preamplifiers are combined by columns and rows at two ends of the detector, and then the shaped signals are sampled by flash ADCs. With the position reconstructed algorithm implemented in FPGA which analyzes the charge division and column and row number of signals, the 3-D position information of neutron events can be obtained. The position resolution and counting rate performance of this method are analyzed, and the comparison to the delay-line readout method is also given. With the multiplex readout method, the scale of readout electronics can be greatly reduced and a good position resolution can be reached. A readout electronics system for a detector module which consists 4 × 10 straw tubes is designed based on this method, and the test with neutron beam shows an average 3-D spatial resolution of 4 × 4 × 6.8mm3.

  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.; 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.

  9. 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 °.

  10. High-resolution and high-intensity neutron diffractometer with linear position-sensitive detector

    NASA Astrophysics Data System (ADS)

    Lee, Chang-Hee; Moon, Myung-Kook; Em, V. T.; Choi, Young-Nam; Oh, Hwa-Suk; Nam, Uk-Won

    2003-08-01

    The characteristics of a neutron diffractometer using a 3He one-dimensional position-sensitive detector (PSD) with delay line readout, a 200 (length) × 100 (height) mm 2 active window and 2.5 mm spatial resolution have been studied and compared with those of the High-Resolution Powder Diffractometer (HRPD) of KAERI with 32 3He conventional tube (∅50 mm) detectors and Soller collimators (10') before detectors. For the sample to PSD distance R=1200 mm, the PSD subtends 8° angle of 2 θ and provides the resolution and the peak-to-background ratio close to that for HRPD. Time for scanning (with the same statistics) of a 0-160° interval is about 1.6 times longer and the multi-PSD system providing efficiency about 10 times higher than HRPD is proposed. Because of the small angle subtended by the PSD, the parasitic peaks from the sample environment are eliminated and operation without an oscillating radial collimator is possible. Additionally, the proposed diffractometer has an advantage for small samples.

  11. Evaluation of a Compton scattering camera using 3-D position sensitive CdZnTe detectors

    NASA Astrophysics Data System (ADS)

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

    2001-01-01

    A CZT Compton Camera (CCC) is being built using two three-dimensional (3-D) position-sensitive CZT detectors. Expected system performance was analyzed by analytical and Monte Carlo approaches. Based on the measurement of detector energy and position resolution, the expected angular resolution is ˜3° and ˜2° for a ±30° FOV for 511 keV and 1 MeV γ-rays, respectively. The intrinsic efficiency for a point source 10 cm from the first detector surface ranges from 1.5×10 -4 to 8.8×10 -6 for 500 keV-3 MeV.

  12. 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.

  13. A position sensitive time of flight detector for heavy ion ERD

    NASA Astrophysics Data System (ADS)

    Eschbaumer, S.; Bergmaier, A.; Dollinger, G.

    2016-03-01

    A new 2D position sensitive time of flight detector for heavy ion ERD has been developed. The detector features separate time and position measurement in a straight geometry. An electrostatic lens focuses the secondary electrons ejected from a carbon foil onto a channel plate stack maintaining the position information despite the electron momentum distribution. For position readout a 2D Backgammon anode is used. A position resolution of <0.6 mm (FWHM) and a time resolution of 96 ps (FWHM) is demonstrated.

  14. Position sensitive detectors for the proposed AXAF imaging optical/UV monitor (AXIOM)

    NASA Astrophysics Data System (ADS)

    Allington-Smith, J. R.; Mason, I. M.; Schwarz, H. E.; Culhane, J. L.

    1985-02-01

    A description is given of the imaging detectors of the AXIOM instrument proposed for NASA's Advanced X-ray Astrophysics Facility (AXAF). The instrument is aligned with the X-ray telescope and consists of a diffraction limited, 30-cm aperture, telescope with redundant position sensitive detectors at the focus. This allows simultaneous imaging at optical and near UV wavelengths of the X-ray target objects. The proposed detectors cover a field of view of 8.5 x 8.5 sq arcmin with a resolution of 1 arcsec (= 50 microns FWHM). The quantum efficiency peaks at 30 percent and exceeds 10 percent over the wavelength range 125 to 540 nm. The detector design consists of a bi-alkali photocathode on a UV-transmitting window, proximity focussed onto a microchannel plate intensifier with a wedge and strip readout system, and is optimized for high count rates both from point sources and from the sky background.

  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. Performance of BF{sub 3} Filled Position Sensitive Neutron Detector

    SciTech Connect

    Desai, Shraddha S.; Devan, Shylaja; Krishna, P. S. R.

    2011-07-15

    {sup 3}He filled position sensitive detectors (PSD)s developed in-house are successfully used for neutron scattering studies at Dhruva. However recent global scarcity of {sup 3}He has made it essential to find an alternative. It is very difficult to meet performance capabilities of {sup 3}He for neutron detection in any of the alternate materials. Among various alternatives, BF{sub 3} gas can be one. We have recently put an effort to evaluate performance of BF{sub 3} based PSD. For that a PSD filled with BF{sub 3} gas at 0.8 bar pressure is fabricated and characterized. Performances of the same with Pu-Be source and at Hi-Q Diffractometer, Dhruva are reported in this paper. Diffraction spectra from standard samples Fe and Si at wavelength 0.783 A were recorded. It is found that while position resolution of the BF{sub 3} filled PSD is comparable but the efficiency is 20 times less than that of a {sup 3}He(12 bar) filled PSD.

  17. Characterization of two resistive anode encoder position sensitive detectors for use in ion microscopy

    NASA Astrophysics Data System (ADS)

    Brigham, Robert H.; Bleiler, Roger J.; McNitt, Paul J.; Reed, David A.; Fleming, Ronald H.

    1993-02-01

    Both the standard resistive anode encoder (RAE) position sensitive ion detector and a new faster version have been adapted for use with CAMECA IMS-3f/4f imaging secondary-ion mass spectroscopy instruments. Each detector includes a dual microchannel plate image intensifier mounted in front of a resistive anode. The conversion efficiencies of the standard and fast detectors are 60% and 55%, respectively. The high count rates attainable with the fast detector require high strip-current microchannel plates for optimum performance. The mass bias of these detectors is proportional to (mass)1/2 and can be compensated by adjustment of detector supply voltage. The response across the active area of these detectors is uniform to within 3% with the greatest deviations occurring at the periphery. Distortion and pixel-to-pixel bias are negligible with the standard RAE, but noticeable in the prototype of the fast RAE. Software has been developed that corrects pixel-to-pixel bias. The dead times of the standard and fast RAE systems are 4.3±0.1 μs and 330±2 ns which limit practical count rates to about 40 000 and 600 000 Hz, respectively. For many applications, the higher ion arrival rates and dynamic range of the fast RAE imaging system more than compensate for the increased pixel-to-pixel bias and distortion and the small decrease in conversion efficiency.

  18. 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.

  19. Reconstruction-free sensitive wavefront sensor based on continuous position sensitive detectors.

    PubMed

    Godin, Thomas; Fromager, Michael; Cagniot, Emmanuel; Brunel, Marc; Aït-Ameur, Kamel

    2013-12-01

    We propose a new device that is able to perform highly sensitive wavefront measurements based on the use of continuous position sensitive detectors and without resorting to any reconstruction process. We demonstrate experimentally its ability to measure small wavefront distortions through the characterization of pump-induced refractive index changes in laser material. In addition, it is shown using computer-generated holograms that this device can detect phase discontinuities as well as improve the quality of sharp phase variations measurements. Results are compared to reference Shack-Hartmann measurements, and dramatic enhancements are obtained.

  20. Imaging, Detection, and Identification Algorithms for Position-Sensitive Gamma-Ray Detectors

    NASA Astrophysics Data System (ADS)

    Wahl, Christopher G.

    Three-dimensional-position-sensitive semiconductors record both the locations and energies of gamma-ray interactions with high resolution, enabling spectroscopy and imaging of gamma-ray-emitting materials. Imaging enables the detection of point sources of gamma rays in an otherwise extended-source background, even when the background spectrum is unknown and may share the point source's spectrum. The generalized likelihood ratio test (GLRT) and source-intensity test (SIT) are applied to this situation to detect one-or-more unshielded point sources from a library of isotopes in a spectrally unknown or known background when the background intensity varies spatially by a factor of two or less. In addition to estimating the number of sources present, their activities, isotopes, and directions from the detector are estimated. Experimental and some simulated results are presented for a single detector and an 18-detector array of 2 cm by 2 cm by 1.5 cm CdZnTe crystals and compared with the performance of spectral-only detection when the background and source are assumed to be spectrally different. Furthermore, the expected detection performance of the 18-detector array system is investigated statistically using experimental data in the case where the background is distinct spectrally from the point source and the possible source location and isotopic identity are known. Including imaging gave at least 7% higher SNR compared to ignoring the image dimension. Also, imaging methods based on the maximum-likelihood, expectation-maximization method are introduced to determine the spatial distribution of isotopes and to find the activity distributions within targets moving with known motion through a radioactive background. Software has also been developed to support the analysis of the data from 3D-position-sensitive spectroscopic systems, for a range of detector designs and applications. The software design and unique features that allow fast multidimensional data analysis are

  1. 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)

  2. New Developments in the Position Sensitive Detectors Based on Microchannel Plates

    NASA Astrophysics Data System (ADS)

    Tremsin, A. S.; Siegmund, O. H. W.

    2002-11-01

    We report on the latest developments in position sensitive photon counting detectors based on microchannel plates. Substantial improvement of the spatial resolution was achieved with introduction of new readout technology, namely crossed strip (XS) anode, and corresponding processing electronics. The spatial resolution of XS readout appeared to be as small as ~3-4 μm FWHM. Reduction of the total detector gain (down to 106 and potentially lower) without compromising the spatial accuracy allows detector operation at much higher local and global counting rates since the microchannel recharge time becomes smaller. Recent developments of novel microchannel plate technologies provide basis for substantial increase of the spectral sensitivity and quantum efficiency of MCP detectors. We have tested a number of new Silicon micromachined MCPs The new MCP technologies should allow deposition of completely new photocathode materials directly on the front surface of microchannel plates (opaque photocathodes). Opposite to standard glass MCPs new Silicon MCPs can sustain high temperatures (-800 C°) required for the photocathode deposition and activation processes.

  3. 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.

  4. Parameter correction method for dual position-sensitive-detector-based unit.

    PubMed

    Mao, Shuai; Hu, Pengcheng; Ding, XueMei; Tan, JiuBin

    2016-05-20

    A dual position-sensitive-detector (PSD)-based unit can be used for angular measurements of a multi-degree-of-freedom measurement system and a laser interferometry-based sensing and tracking system. In order to ensure the precision of incident beam direction measurement for a PSD-based unit, model and autoreflection alignment methods for correction of PSD-based unit parameters are proposed. Experimental results demonstrate the deviations between the angular measurements obtained using a dual PSD-based unit and an autocollimator varied by 70″, 20″, and 1″ for three runs of the autoreflection alignment method, respectively, and the model method deviations all varied by 1″ in the 1000″ measurement range for three runs. It is therefore concluded that the model method is more reliable than the autoreflection alignment method for ensuring the accuracy of a dual PSD-based unit. PMID:27411134

  5. Parameter correction method for dual position-sensitive-detector-based unit.

    PubMed

    Mao, Shuai; Hu, Pengcheng; Ding, XueMei; Tan, JiuBin

    2016-05-20

    A dual position-sensitive-detector (PSD)-based unit can be used for angular measurements of a multi-degree-of-freedom measurement system and a laser interferometry-based sensing and tracking system. In order to ensure the precision of incident beam direction measurement for a PSD-based unit, model and autoreflection alignment methods for correction of PSD-based unit parameters are proposed. Experimental results demonstrate the deviations between the angular measurements obtained using a dual PSD-based unit and an autocollimator varied by 70″, 20″, and 1″ for three runs of the autoreflection alignment method, respectively, and the model method deviations all varied by 1″ in the 1000″ measurement range for three runs. It is therefore concluded that the model method is more reliable than the autoreflection alignment method for ensuring the accuracy of a dual PSD-based unit.

  6. Measuring Relative-Story Displacement and Local Inclination Angle Using Multiple Position-Sensitive Detectors

    PubMed Central

    Matsuya, Iwao; Katamura, Ryuta; Sato, Maya; Iba, Miroku; Kondo, Hideaki; Kanekawa, Kiyoshi; Takahashi, Motoichi; Hatada, Tomohiko; Nitta, Yoshihiro; Tanii, Takashi; Shoji, Shuichi; Nishitani, Akira; Ohdomari, Iwao

    2010-01-01

    We propose a novel sensor system for monitoring the structural health of a building. The system optically measures the relative-story displacement during earthquakes for detecting any deformations of building elements. The sensor unit is composed of three position sensitive detectors (PSDs) and lenses capable of measuring the relative-story displacement precisely, even if the PSD unit was inclined in response to the seismic vibration. For verification, laboratory tests were carried out using an Xθ-stage and a shaking table. The static experiment verified that the sensor could measure the local inclination angle as well as the lateral displacement. The dynamic experiment revealed that the accuracy of the sensor was 150 μm in the relative-displacement measurement and 100 μrad in the inclination angle measurement. These results indicate that the proposed sensor system has sufficient accuracy for the measurement of relative-story displacement in response to the seismic vibration. PMID:22163434

  7. Resonant inelastic hard x-ray scattering with diced analyzer crystals and position-sensitive detectors

    SciTech Connect

    Huotari, S.; Albergamo, F.; Vanko, Gy.; Verbeni, R.; Monaco, G.

    2006-05-15

    A novel design of a high-resolution spectrometer is proposed for emission spectroscopy and resonant inelastic hard x-ray scattering applications. The spectrometer is based on a Rowland circle geometry with a diced analyzer crystal and a position-sensitive detector. The individual flat crystallites of the diced analyzer introduce a well-defined linear position-energy relationship within the analyzer focus. This effect can be exploited to measure emission spectra with an unprecedented resolution. For demonstration, a spectrometer was constructed using a diced Si(553) analyzer working at the Cu K edge with an intrinsic resolution of 60 meV. With the proposed design, spectrometers operating at the K edges of 3d transition metals can have intrinsic resolutions below 100 meV even with analyzer crystals not working in Bragg-backscattering conditions.

  8. New Data Collection Subsystem for Powder Neutron Diffractometer with Position Sensitive Detectors

    NASA Astrophysics Data System (ADS)

    Drab, Martin; Kalvoda, Ladislav; Vratislav, Stanislav; Dlouha, Maja

    2012-02-01

    Project INDECS (Integrated Neutron Diffraction Experiment Control System) is a newly developed software system created for the purpose of data acquisition from, and controlling of the upgraded version of the KSN-2 powder neutron diffractometer equipped with Position Sensitive Detectors. The KSN-2 neutron diffractometer (belonging to LND, DSSE, FNSPE, CTU in Prague, CZ, placed at the NRI, Řež near Prague, CZ) was recently upgraded with the possibility to contain up to three parallel linear PSDs which can be mounted on the detector arm instead of the original single counter detector. That was the motivation for the project INDECS to be started. For the actual data acquisition and initial data analysis of the raw sampled signals within the project INDECS a special modular structure called the PSD Acquisition Path (or PSDAP) was designed. Raw sampled signals from either end of the PSD are taken as the main input to the subsystem. The signals are then split into multiple events, analyzed for the position of the obtained events on the PSD, and a histogram of the diffraction events is created as the main output of this subsystem. Moreover, the PSDAP is capable of storing the raw signals either before event splitting or after, so that later the whole process of acquisition can be replayed in software, perhaps with different settings of the processing parameters or perhaps even algorithms. It can also be switched into a mode where under special conditions a correction curve specific for the given PSD can be constructed and later in normal operation it can be used to do the corrections of detected event positions to enhance the results on that particular PSD. This whole subsystem then acts as a single modular command unit (External Execution Module or EEM) within the entire system of project INDECS.

  9. 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.

  10. Method of nonlinear correction of two-dimensional position sensitive detector

    NASA Astrophysics Data System (ADS)

    Mo, Changtao; Wang, Ming; Zhang, Guoyu

    2007-12-01

    The position sensitive detector (PSD) is photo-electronic sensor which can detect the position of a light spot incident on its surface. Many types of non-contact dynamic displacement monitoring instruments could be constructed using PSD. How to overcome the influence of non-linearity action is the most important problem to improve measuring precision and reliability of the instrument. The output characteristic of PSD is analyzed. It is found that the output response of sensor is non-linear when the measuring range is large. In this paper we propose a method for correcting non-linearity of PSD sensor based on high precision linearization sub-block integration neural network interpolation. By using conjugate gradient algorithm of neural network which have characteristic to approach arbitrary nonlinear function, the nonlinear mapping between detecting the voltage of sensor and the outputting results are obtained by training neural network under different nonlinear condition. Experiment results indicate that not only the influence of non-linearity is eliminated effectively, but also the output of nerve network is linear.

  11. Evaluation of a Compton scattering camera using 3D position-sensitive CdZnTe detectors

    NASA Astrophysics Data System (ADS)

    Du, Yanfeng; He, Zhong; Knoll, Glenn F.; Wehe, David K.; Li, Weiqi

    1999-10-01

    A CZT Compton Camera (CCC) is being built using two 3D position sensitive CZT detectors. Expected system performance was analyzed by analytical and Monte Carlo approaches. Based on the measurement of detector energy and position resolution, the expected angular resolution is approximately 3 degree and approximately 2 degrees for a +/- 30 degrees FOV for 511 keV and 1 MeV (gamma) -rays, respectively. The intrinsic efficiency for a point source 10 cm from the first detector surface ranges from 1.5 X 10-4 to 8.8 X 10-6 for 500 keV to 3 MeV.

  12. Position sensitive photon detectors for nuclear physics, particle physics and healthcare applications

    NASA Astrophysics Data System (ADS)

    Seitz, B.

    2012-01-01

    Modern experiments in hadronic physics require detector systems capable of identifying and reconstructing all final-state particles and their momentum vectors. Imaging Cherenkov counters (RICH and DIRC) are frequently employed in nuclear and particle physics experiments. These detectors require high-rate, single-photon capable light detection system with sufficient granularity and position resolution. Several candidate systems are available, ranging from multi-anode photomultiplier tubes to micro-channel plate systems to silicon photomultipliers. Each of these detection solutions has particular advantages and disadvantages. Detailed studies of rate dependence, cross-talk, time-resolution and position resolution for a range of available photon detection solutions are presented. These properties make these photon detection systems ideal for radionuclide imaging applications. Cherenkov radiation can also be used for medical imaging applications. Two different applications using the Cherenkov effect for radionuclide imaging will be reviewed.

  13. A position-sensitive germanium detector for gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Varnell, L. S.; Ling, J. C.; Mahoney, W. A.; Jacobson, A. S.; Pehl, R. H.; Goulding, F. S.; Landis, D. A.; Luke, P. N.; Madden, N. W.

    1984-01-01

    The critical problem in high-resolution cosmic gamma-ray spectroscopy in the energy range from 0.02 to 10 MeV is the limited spectral sensitivity of the detectors used. This results from the small effective area of the detectors and the high background noise due to induced radioactivity and scattering in the detectors' high-energy particle environment. The effective area can be increased by increasing the number of detectors, but this becomes prohibitive because of the size and expense of the resulting instrument. We have taken a new approach: a segmented large-volume germanium gamma-ray detector which can effectively discriminate against internal background yet maintain the high spectral resolution and efficiency of conventional coaxial Ge detectors. To verify this concept, a planar detector divided into two segments has been fabricated and laboratory measurements agree well with Monte Carlo calculations. A large coaxial detector which will be divided into five segments is being built using the techniques developed for the planar detector. Monte Carlo calculations show that the sensitivity (minimum detectable flux) of the segmented coaxial detector is a factor of 2-3 better than conventional detectors because of the reduction in the internal background.

  14. 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.

  15. A Monte Carlo simulation comparing hydrocarbons as stopping gases for position sensitive neutron detectors

    NASA Astrophysics Data System (ADS)

    Doumas, A.; Smith, G. C.

    2009-12-01

    Various neutron detectors are being developed for the next generation user facilities, which incorporate new as well as existing approaches for the detection of thermal neutrons. Improvements in neutron detector efficiency, detector size and position resolution have occurred over the last three decades and further advances are expected in the next ten years. Since gas detectors are expected to continue in a key role for future thermal neutron experiments, it is advantageous to review some of the criteria for the choice of proton/triton stopping gases for gas-based detectors. Monte Carlo simulations, using the group of programs "Stopping and Range of Ions in Matter", have been run to determine key performance characteristics for neutron detectors which utilize the reaction 3He(n,p)t. This paper will focus on investigating the use of three common hydrocarbons and CF 4 as stopping gases for thermal neutron detectors. A discussion of these gases will include their behavior in terms of proton and triton range, ion distribution and straggle.

  16. 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.

  17. 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.

  18. Comprehensive simulation of the response of a silicon strip detector for position-sensitive measurements of X-rays

    NASA Astrophysics Data System (ADS)

    Wiącek, P.; Dąbrowski, W.

    2005-10-01

    The paper describes a comprehensive simulation method to evaluate X-ray imaging response of a silicon strip detector with particular emphasis on the charge-sharing effects. The simulation steps include: generation of the initial charge distribution in the detector volume, transport of generated charge in the detector volume, calculation of charges induced in the readout strips, discrimination of noisy electronic signals, and finally determination of the count efficiency vs. photon position as a function of the discrimination threshold. The developed simulation tools are useful for optimising the designs and operating parameters of silicon strip detectors used as 1-D position sensitive devices in experimental techniques like X-ray powder diffraction, X-ray high-resolution diffraction and small angle X-ray scattering, using laboratory X-ray sources. The response of the detector as a function of the detector bias and discrimination threshold has been investigated for two measurement configurations: irradiation from the strip-side and from the back-side.

  19. 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.

  20. Organic Position-Sensitive Detectors Based on ZnO:Al and CuPc:C60.

    PubMed

    Morimune, Taichiro; Kajii, Hirotake; Nishimaru, Hiroki; Ono, Shinji

    2016-04-01

    Organic position-sensitive detector (OPSD) based on copper phthalocyanine CuPc:fullerene C60 bulk-heterojunction with an inverted structure have been fabricated using aluminum doped ZnO (ZnO:Al) as a resistive layer, which is prepared by sol-gel method. The resistance length of the one-dimensional PSD is fixed at 5 mm, and the Ag common electrode is fabricated by vacuum evaporation within the 100-µm width. The current density-voltage characteristics with different structures of photodetector, the influence of ZnO:Al resistivity on the thickness and the position characteristics of PSDs are investigated. The experimental results indicate that the architecture, which uses an inverted structure, increases sensitivity under red light illumination compared to the conventional structure. In addition, the thickness of the ZnO:Al has influence on the position characteristics. The resistivity of ZnO:A film with Al doping concentration of 2 mol% prepared in this study is around 150 Ωcm and it increases from less than approximately 400 nm-thickness. These characteristics seem to be correlated with the properties of ZnO:AI resistive layer. For a device with a 620 nm-thick ZnO:Al layer, the measured position values obtained from the output photocurrent agree with the actual position values under red laser light illumination. CuPc:C60 OPSD with an inverted structure exhibits red light sensitivity, high incident-photon-to-current conversion efficiency of above 80% at -3 V and linearity error of 5.9% at -2 V. PMID:27451643

  1. Time and position sensitive single photon detector for scintillator read-out

    NASA Astrophysics Data System (ADS)

    Schössler, S.; Bromberger, B.; Brandis, M.; Schmidt, L. Ph H.; Tittelmeier, K.; Czasch, A.; Dangendorf, V.; Jagutzki, O.

    2012-02-01

    We have developed a photon counting detector system for combined neutron and γ radiography which can determine position, time and intensity of a secondary photon flash created by a high-energy particle or photon within a scintillator screen. The system is based on a micro-channel plate photomultiplier concept utilizing image charge coupling to a position- and time-sensitive read-out anode placed outside the vacuum tube in air, aided by a standard photomultiplier and very fast pulse-height analyzing electronics. Due to the low dead time of all system components it can cope with the high throughput demands of a proposed combined fast neutron and dual discrete energy γ radiography method (FNDDER). We show tests with different types of delay-line read-out anodes and present a novel pulse-height-to-time converter circuit with its potential to discriminate γ energies for the projected FNDDER devices for an automated cargo container inspection system (ACCIS).

  2. 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.

  3. 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.

  4. The sources of inspiration in research on position-sensitive detectors

    NASA Astrophysics Data System (ADS)

    Charpak, G.

    1988-12-01

    The high-energy experimental physicist is constantly confronted with the problem of identifying and localizing particles, charged or neutral. The community of high-energy physicists has thus produced a variety of original methods which have found, or are beginning to find, applications in many fields that are remote from this discipline. New hadron accelerators which are foreseen for the year 2000 raise formidable problems. To take an extreme case, beams crossing at 5 ns intervals are being considered, with several interactions per crossing and with collision multiplicities close to 100. Should a high-energy experimental physicist who is interested in research on particle detectors, limit his horizon to these questions? Even if most of his effort is legitimately concentrated on solving the specific problems encountered with the projected accelerators, it would be a mistake for him to limit his activity to reaching only this goal. In many fields there is considerable demand for improvement in the methods of radiation imaging. I will list some of them, and illustrate my point — which is that contributing of this field is both fruitful and cross-fertilizing — with examples from the activity of our own group at CERN. I apologize for not doing justice to the many other efforts made in the same direction by other groups or laboratories, but the proceedings of this conference will already be illuminating in this respect.

  5. 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.

  6. 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.

  7. 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. PMID:25725834

  8. 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.

  9. Polarization analysis for the 2D position-sensitive detector of the HADAS reflectometer in Jülich

    NASA Astrophysics Data System (ADS)

    Rücker, U.; Bergs, W.; Alefeld, B.; Kentzinger, E.; Brückel, Th.

    2001-03-01

    A neutron reflectometer with polarization analysis is being built on the basis of the HADAS spectrometer in the neutron guide hall at the research reactor FRJ-2 (DIDO) in Jülich. The new instrument is optimized for reflectivity and diffuse scattering measurements under grazing incidence on layered magnetic structures with thicknesses in the nm range. In order to measure diffuse scattering with polarization analysis, the 2D position-sensitive detector has been equipped with a polarization analyser that consists of a stack of supermirrors parallel to the scattering plane. First tests have revealed that the resolution of the instrument is not reduced by the polarization analyser. A flipping ratio of 20 has been achieved already during the first experiment.

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

    PubMed Central

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

    2014-01-01

    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 mm3 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

  11. 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

  12. 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.

  13. The residual stress instrument with optimized Si(2 2 0) monochromator and position-sensitive detector at HANARO

    NASA Astrophysics Data System (ADS)

    Lee, Chang-Hee; Moon, Myung-Kook; Em, Vyacheslav T.; Choi, Young-Hyun; Cheon, Jong-Kyu; Nam, Uk-Won; Kong, Kyung-Nam

    2005-06-01

    An upgraded residual stress instrument at the HANARO reactor of the KAERI is described. A horizontally focusing bent perfect crystal Si(2 2 0) monochromator (instead of a mosaic vertical focusing Ge monochromator) is installed in a drum with a tunable (2 θM=0-60°) take-off angle/wavelength. A specially designed position-sensitive detector (60% efficiency for λ=1.8 A) with 200 mm (instead of 100 mm) high-active area is used. There are no Soller type collimators in the instrument. The minimum possible monochromator to sample distance, L=2 m, and sample to detector distance, L=1.2 m, were found to be optimal. The new PSD and bent Si(2 2 0) monochromator combined with the possibility of selecting an appropriate wavelength resulted in about a ten-fold gain in data collection rate. The optimal reflections of austenitic and ferritic steels, aluminum and nickel for stress measurements with a Si(2 2 0) monochromator were chosen experimentally. The ability of the instrument to make strain measurements deep inside the austenitic and ferritic steels has been tested. For the chosen reflections and wavelengths, no shift of peak position (apparent strain) was observed up to 56 mm length of path.

  14. Fast x-ray scattering measurements on molten alumina using a 120{degree} curved position sensitive detector.

    SciTech Connect

    Hennet, L.; Thiaudiere, D.; Gailhanou, M.; Landron, C.; Coutures, J.-P.; Price, D. L.; C.R.M.H.T.; LURE; Univ. de Perpignan

    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 CO{sub 2} laser was used to melt the sample and the temperature was measured using an optical pyrometer operating at 0.85 {mu}m. 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{sup o} 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 Angstroms{sup -1}). The intensity was comparable with a 1 h measurement with a NaI (Tl) scintillator scanned over the 120 2{theta} 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.

  15. 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.

  16. 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.

  17. 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

  18. A BGO/GSO position sensitive block detector for a high resolution positron emission tomography with depth of interaction detection capability

    SciTech Connect

    Yamamoto, S.

    1996-12-31

    We developed a position sensitive block detector with depth of interaction detection capability for positron emission tomography (PET). The detector consists of 6 x 8 array of GSO scintillators, 6 x 8 array of BGO scintillators and two dual photomultiplier tubes (PMT). The GSO scintillators are optically coupled to front surface of the BGO scintillators. The position of 6 x 8 scintillators are determined by the Anger principle and depth of interaction position is determined by using the pulse shape analysis of GSOs and BGOs. Performance of the block detector was measured. Position distribution of the developed BGO/GSO block detector was little distorted. However the separation of the spots was still enough to distinguish the scintillators in transaxial and axial directions. Since pulse shape distribution using a developed simple pulse shape analyzer had two peaks, it is possible to separate the GSOs and BGOs for depth of interaction detection. With these results, a high resolution PET with depth of interaction detection capability will be possible using the developed BGO/GSO block detectors.

  19. 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.

  20. 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.

  1. 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.

  2. Evaluation of an integrated Fourier-transform spectrometer utilizing a lateral effect position sensitive detector with a multi-channel Fabry Perot interferometer

    NASA Astrophysics Data System (ADS)

    Andersson, H. A.; Manuilskiy, A.; Thungström, G.; Nilsson, H.-E.

    2008-04-01

    The basis of this paper is the evaluation of an integrated multi-channel Fourier-transform (FT) spectrometer based on a multi-channel wedge Fabry-Perot interferometer and a one-dimensional lateral effect position sensitive detector (PSD). The use of a PSD for an interferogram readout allows for a simple scanning mechanism with no requirement for any position reference. The use of a wedge-shaped interferometer makes it possible to integrate it directly onto the PSD surface, thus producing a very compact spectrometer. The capabilities of the spectrometer are demonstrated by absorption spectral measurements using a reference sample. In addition, spectral measurements on 532 nm DPSS and 632.8 nm He-Ne lasers are presented. The resolution of the spectrometer is approximately 5 nm. The evaluated spectrometer set-up can be used in applications where compact and low cost spectrometers are required, such as in process control and in education. Further, it is shown that there are deteriorations in very high accuracy position measurements, which are caused by changes in incident light intensity. A model describing the above-mentioned nonlinearities was developed based on analysing the equivalent circuit for PSDs and parameters such as leakage current and serial resistance. Additionally, a method is proposed to assist in the reduction of the nonlinearity caused by this effect.

  3. Towards a deep characterization of a 64-fold-pixelated position sensitive detector for a new {gamma}-scanning system of HPGe segmented detectors

    SciTech Connect

    Hernandez-Prieto, A.; Quintana, B.

    2011-07-01

    Characterization of the electrical response of the HPGe segmented detectors is one of the current goals for the Nuclear Physics community in order to perform {gamma}-ray tracking or even imaging with these detectors. For this purpose, scanning devices have to be developed to achieve the signal-position association with the highest precision. In this laboratory, a new scanning system, SALSA (Salamanca Lyso-based Scanning Array), consisting on a high spatial resolution {gamma} camera, is a under development. In this work the whole scanning system is presented and first results for the characterization of the {gamma} camera are shown. (authors)

  4. 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

  5. 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.

  6. 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). PMID:17645997

  7. 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.; Cherches, C.; Cui, Y.; De Geronimo, G.; Fried, J.; Hodges, D.; Hossain, A.; Lee, W.; et al

    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

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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

    2012-01-01

    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

  14. Development of the Position Sensitive Ionization Chamber for ANASEN

    NASA Astrophysics Data System (ADS)

    Gardiner, Hannah; Blackmon, Jeff; Deibel, Catherine; Gardiner, Emily; Lai, Jianping; Lauer, Amber; Linhardt, Laura; Macon, Kevin; Rasco, Charlie; Baby, Lagy; Koshchiy, Yevegn; Rogachev, Grigory; Santiago-Gonzales, Daniel; Wiedenhoever, Ingo; Bardayan, Dan; Matos, Milan

    2013-10-01

    The Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN) is a charged-particle detector array developed for reaction studies using radioactive ion beams to help improve understanding of the nuclear reactions important in stellar explosions. A gas-filled ionization chamber with two position-sensitive anode wire grid planes read out in 32 channels, and 12 alternating anode/cathode planes was developed and tested for use with ANASEN to identify the kinematic trajectory and atomic number of recoiling heavy ions by their relative energy loss. The position sensitive grids are arranged perpendicularly to each other in order to determine the x-y position of each ion with better than 4 mm resolution. This ionization chamber was tested using a stable beam of 12C at FSU. We report on the performance of this test experiment and plans for measurements with radioactive ion beams at FSU. Two other versions of the detector have been constructed and are now in place at the National Superconducting Cyclotron Laboratory and at the ATLAS accelerator facility at Argonne National Laboratory.

  15. ISS/IDS Detector Study

    SciTech Connect

    Cervera-Villanueva, A.

    2008-02-21

    This article summarises the results obtained by the detector working group of the 'International Scooping Study' (ISS) of a future neutrino oscillations facility. Special emphasis is put on far detectors, for which some of the main issues are identified. A detector R and D strategy in the context of the 'International Design Study' (IDS) for a neutrino factory is also presented.

  16. Position sensitive detection of neutrons in high radiation background field

    SciTech Connect

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

    2014-01-15

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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Two-dimensional position sensitive ionization chamber with GEM

    NASA Astrophysics Data System (ADS)

    Kitamura, Noritaka; Noro, Tetsuo; Sakaguchi, Satoshi; Takao, Hideaki; Nishio, Yasutaka

    2014-09-01

    We have been developing a multi-anode ionization chamber for Accelerator Mass Spectrometry (AMS) at Kyushu University. Furthermore, we are planning to construct a neutron detector with high position resolution by combining the chamber with Gas Electron Multiplier (GEM) and a neutron converter. One of purposes is the measurement of p-> , pn knockout reaction from unstable nuclei. The multi-anode ionization chamber is composed of subdivided multiple anodes, a cathode to produce an uniform electric field, and a Frisch grid. The chamber must have position sensitivity because obtaining a beam profile is required for AMS measurements, where counting loss should be avoided. Also in the case of the neutron detector, it is necessary to measure the position to deduce the scattering angles. We have recently established a two-dimensional position readout system by the following methods: the measurement of horizontal position is enabled by trimming some anodes into wedge-like shape, and vertical position can be determined by the ratio of induced charge on the grid to the total charge on anodes. In addition, improvement of S/N ratio is important for isotope separation and position resolution. We installed a rectangular-shaped GEM and tried improving S/N ratio by electron amplification.

  4. 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.

  5. 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.

  6. 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...

  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...

  8. 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...

  9. 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...

  10. 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...

  11. Simulated Performance of Algorithms for the Localization of Radioactive Sources from a Position Sensitive Radiation Detecting System (COCAE)

    SciTech Connect

    Karafasoulis, K.; Zachariadou, K.; Seferlis, S.; Kaissas, I.; Potiriadis, C.; Lambropoulos, C.; Loukas, D.

    2011-12-13

    Simulation studies are presented regarding the performance of algorithms that localize point-like radioactive sources detected by a position sensitive portable radiation instrument (COCAE). The source direction is estimated by using the List Mode Maximum Likelihood Expectation Maximization (LM-ML-EM) imaging algorithm. Furthermore, the source-to-detector distance is evaluated by three different algorithms based on the photo-peak count information of each detecting layer, the quality of the reconstructed source image, and the triangulation method. These algorithms have been tested on a large number of simulated photons over a wide energy range (from 200 keV to 2 MeV) emitted by point-like radioactive sources located at different orientations and source-to-detector distances.

  12. 2 Dimensional position sensitive XAFS by using in-house X-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Shinoda, Kozo; Suzuki, Shigeru; Kuribayashi, Masaru; Taguchi, Takeyoshi

    2009-09-01

    Position sensitive XAFS measurements by using the in-house X-ray spectrometer and the position sensitive X-ray detector were attempted. The in-house spectrometer produces monochromized divergent X-ray beam. Therefore, an extended direct-beam image projected on the detector can be taken, and its extension rate is depending on the arrangement of the sample and the detector. A position sensitive XAFS measurement was demonstrated by using Ni metal foil and NiO powder as a model sample. Ge(220) or Si(400) Johansson-type bent single-crystal was used as monochromator, and Mo and LaB6 were used as the target and filament, respectively. Tube voltage and current were operated at 16 kV and 100 mA (1.6 kW). XAFS spectra were measured by transmission-mode with sample set/reset method and required time of each experiment is about 6 hours in total. It was confirmed that metal and oxide spectra with enough quality for structural analysis were clearly separated by each position in the sample.

  13. 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.

  14. A Beta-Particle Hodoscope Constructed Using Scintillating Optical Fibers and Position Sensitive Photomultiplier Tubes

    SciTech Connect

    Orrell, John L.; Aalseth, Craig E.; Day, Anthony R.; Fast, Jim; Hossbach, Todd W.; Lidey, Lance S.; Ripplinger, Mike D.; Schrom, Brian T.

    2006-09-19

    A hodoscopic detector was constructed using a position-sensitive plastic scintillator active area to determine the location of beta-active micron-sized particulates on air filters. The ability to locate beta active particulates on airsample filters is a tool for environmental monitoring of anthropogenic production of radioactive material. A robust, field-deployable instrument can provide localization of radioactive particulate with position resolution of a few millimeters. The detector employs a novel configuration of scintillating plastic elements usually employed at much higher charged particle energies. A filter is placed on this element for assay. The detector is intended to be sensitive to activity greater than 1 Bq. The physical design, position reconstruction method, and expected detector sensitivity are reported.

  15. 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.

  16. 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.

  17. Spectroscopy of highly-ionized atoms using position-sensitive detection

    NASA Astrophysics Data System (ADS)

    Kukla, K. W.; Livingston, A. E.; Serpa, F. G.; Zacarias, A. S.; Berry, H. G.; Dunford, R. W.; Kanter, E.; Cheng, S.; Suleiman, J.; Curtis, L. J.; Träbert, E.

    1993-06-01

    We report new results of atomic structure and atomic lifetime measurements in highly-ionized few electron atoms obtained using position-sensitive detection of extreme ultraviolet emission from excited fast ions. Data is presented from experiments run at the Notre Dame Tandem Accelerator and at the Argonne ATLAS facility using beam-foil spectroscopy with a photon-counting position-sensitive imaging detector. The results include excited state lifetimes in Si XI and Si XII involving both resonance transitions and Rydberg transitions, spectra of high-ionized He-like, Li-like, and Be-like nickel including comparisons of electron capture and excitation processes for charge selected beams and spectra and lifetimes in highly-charged bromine ions for both allowed and forbidden transitions.

  18. Construction and commissioning of a position-sensitive ionization chamber

    NASA Astrophysics Data System (ADS)

    Kwag, M. S.; Chae, K. Y.; Cha, S. M.; Kim, A.; Kim, M. J.; Lee, E. J.; Lee, J. H.

    2016-05-01

    A position-sensitive ionization chamber has been constructed and commissioned at the Physics Department of Sungkyunkwan University to extract position information on incident charged particles for future nuclear reaction measurements. By utilizing the newly-designed position-sensitive anodes and the previously-commissioned portable gas-filled ionization chamber by Chae et al., position information on incident particles could be obtained. The device was tested with an 241Am α-emitting source, and the standard deviation of the fitted Gaussian distribution was measured to be 1.76 mm when a collimator with a 2 mm hole was used.

  19. Study of cosmic radiation by underground detectors

    NASA Astrophysics Data System (ADS)

    de Marzo, C.

    1992-04-01

    The study of cosmic radiation using underground detectors has undergone remarkable progress in the last ten years. Today several big underground laboratories are taking data on general problems of particle astrophysics, around the world. The study of the physical content of the mu-signal is reviewed, with special attention given to the recent results obtained at the Gran Sasso Laboratory by means of the MACRO detector, which is the largest apparatus devoted to this research field at present.

  20. 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.

  1. Charge integrating type position-sensitive proportional chamber for time-resolved measurements using intense X-ray sources

    NASA Astrophysics Data System (ADS)

    Mochiki, Koh-ichi; Hasegawa, Ken-ichi

    1985-02-01

    A position-sensitive detecting system for time-resolved diffraction measurements with very intensive X-ray sources has been developed. It consists of a charge integrating type gas-filled detector, multichannel analog multiplexers, a signal processor and a memory (120 ch.×128 phases×24 bits). The detector is 120 mm long in effective length by 10 mm×10 mm in cross section with a single anode of 20 μm diameter. One of the cathode planes consists of 120 cathode strips with a pitch of 1 mm. The spatial resolution is equal to the pitch under a certain detector current limit. The gas gain is adjustable to an appropriate value according to the X-ray intensity range of interest. For experiments with 8 keV X-ray sources, maximum absorption rates of 9×10 7 photons/s·mm with low applied voltage and minimum absorption rates of about 3 photons/s·mm with high applied voltage can be achieved. This system was applied to a time-resolved X-ray diffraction study on frog muscle using a synchrotron radiation source at the Photon Factory and we could collect diffraction patterns with a time resolution of 10 ms and only 10 stimulations.

  2. 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.

  3. 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. PMID:26309235

  4. 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.

  5. 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.

  6. 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.

  7. Recent advances and future perspectives of position sensitive PMT

    NASA Astrophysics Data System (ADS)

    Pani, R.; Pellegrini, R.; Cinti, M. N.; Mattioli, M.; Trotta, C.; Montani, L.; Iurlaro, G.; Trotta, G.; D'Addio, L.; Ridolfi, S.; De Vincentis, G.; Weinberg, I. N.

    2004-01-01

    In recent years there has been a growing interest in developing compact gamma cameras to improve gamma ray imaging for application in nuclear medicine as well as in astrophysics, radiation physics and high energy physics. The gamma cameras based on position sensitive photomultipliers could be the best chance to obtain a realistic and low cost compact gamma camera. Since 1985 the development of position sensitive photo multiplier tubes (PSPMT) has shown the highest rate in technological advancement achieving very compact size (25 × 25 × 20 mm 3) by a novel charge multiplication system. The PSPMT shows the same advantages of a standard gamma camera with the additional possibility to utilize scintillation arrays with pixel dimension less than 1 mm, thus achieving sub-millimeter spatial resolution values. The last technological advance is a PSPMT with Flat Panel structure, named H8500. Its dimension is 50 × 50 mm 2 with a narrow peripheral dead zone to place closely different modules achieving large detection areas. In this paper the technological development of different PSPMT generations is reviewed and some measurements of the first Flat Panel PMT prototype are presented and compared with ones from previous generation. Flat Panel PMT could be the best trade-off between compactness, large detection areas, effective area (packing density) and imaging performance.

  8. Development of arrays of position-sensitive microcalorimeters for Constellation-X

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    We are developing arrays of position-sensitive transition-edge sensor (POST) X-ray detectors for future astronomy missions such as NASA's Constellation-X. The POST consists of multiple absorbers thermally coupled to one or more transition-edge sensor (TES). Each absorber element has a different thermal coupling to the TES. This results in a distribution of different pulse shapes and enables position discrimination between the absorber elements. POST'S are motivated by the desire to achieve the largest possible focal plane area with the fewest number of readout channels and are ideally suited to increasing the Constellation-X focal plane area, without comprising on spatial sampling. Optimizing the performance of POST'S requires careful design of key parameters such as the thermal conductances between the absorbers, TES and the heat sink. as well as the absorber heat capacities. Using recently developed signal processing algorithms we have investigated the trade-off between position-sensitivity, energy resolution and pulse decay time. based on different device design parameters for PoST's. Our new generation of PoST's utilize technology successfully developed on high resolution (approximately 2.5eV) single pixels arrays of Mo/Au TESs. also under development for Constellation-X. This includes noise mitigation features on the TES and low resistivity electroplated absorbers. We report on the first experimental results from these new one and two-channel PoST"s, consisting of all Au and composite Au/Bi absorbers, which are designed to achieve an energy resolution of < 10 eV. coupled with count-rates of 100's per pixel per second and position sensitivity over the energy range 0.3-10 keV.

  9. 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.

  10. [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.

  11. High-speed measurement of rotational anisotropy nonlinear optical harmonic generation using position-sensitive detection.

    PubMed

    Harter, J W; Niu, L; Woss, A J; Hsieh, D

    2015-10-15

    We present a method of performing high-speed rotational anisotropy nonlinear optical harmonic generation experiments at rotational frequencies of several hertz by projecting the harmonic light reflected at different angles from a sample onto a stationary position-sensitive detector. The high rotational speed of the technique, 10(3) to 10(4) times larger than existing methods, permits precise measurements of the crystallographic and electronic symmetries of samples by averaging over low frequency laser-power, beam-pointing, and pulse-width fluctuations. We demonstrate the sensitivity of our technique by resolving the bulk fourfold rotational symmetry of GaAs about its [001] axis using second-harmonic generation. PMID:26469591

  12. Imaging of β particle sources used in medical applications with position sensitive Silicon sensors

    NASA Astrophysics Data System (ADS)

    Caccia, M.; Alemi, M.; Bianchi, C.; Bulgheroni, A.; Cappellini, C.; Conte, L.; Kucewicz, W.; Prest, M.; Vallazza, E.; Sampietro, C.

    2004-06-01

    Real-time dosimetry is a critical issue in most radiotherapy applications. Silicon Ultra fast Cameras for electron and gamma sources In Medical Applications (Nucl. Phys. B 125 (2003) 133) is an EC project addressing the development of an imaging device for extended radioactive sources based on monolithic and hybrid-position-sensitive silicon sensors. Large-area Silicon strip detectors read out by low noise charge integrating chips were used to characterize a 90Sr intravascular brachytherapy source in terms of dose-depth curves in a tissue equivalent material and homogeneity of the activity. The results obtained with the Silicon sensor were compared to measurements with standard certified systems and are reported in the paper.

  13. 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.

  14. 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.

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

    DOE PAGES

    Arnold, C. W.; Tovesson, F.; Meierbachtol, K.; Bredeweg, T.; Jandel, M.; Jorgenson, H. J.; Laptev, A.; Rusev, G.; Shields, D. W.; White, M.; et al

    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

  16. 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. PMID:24307743

  17. Single photon emission imaging by position sensitive PMT

    NASA Astrophysics Data System (ADS)

    Pani, R.; Pellegrini, R.; Soluri, A.; De Vincentis, G.; Scafè, R.; Pergola, A.

    1998-02-01

    Position Sensitive Photo Multiplier Tube (PSPMT) represents a strong technological improvement for Nuclear Medicine imaging. Over the last 10 years Hamamatsu has developed a number of PSPMTs with different shapes and sizes, from 1 in. square up to more recent prototype of 8 in. diameter. The position is continuously detected by centroid method and spatial resolution represents its statistical uncertainty. By coupling PSPMTs to scintillating arrays it was possible to push PMTs near their intrinsic limit. A number of scintillating crystals arranged in a matrix were tested such as: YAP : Ce, NaI(Tl), CsI(Tl) and CsI(Na) with different pixel size (from 0.3×0.3 mm 2 to 2×2 mm 2) with overall dimension from 4×4 cm 2 up to 11 cm diameter. A number of applications in Nuclear Medicine were performed, such as miniature gamma cameras for radiopharmaceutical investigations on little animals where sub-millimeter spatial resolution values were carried out. More recently, the first prototype of dedicated gamma camera for scintimammography has been developed for small cancer detection in the breast.

  18. 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.

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

    SciTech Connect

    Yoo, Sung Shik; Faurie, J.P.; Wang, Kemei; Montano, P.A. |; Huang Qiang; Rodricks, B.

    1993-09-01

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

  20. 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

  1. 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

  2. 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

  3. Alpha particle response study of polycrstalline diamond radiation detector

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Topkar, Anita

    2016-05-01

    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.

  4. Reciprocal-Space Analysis of Compositional Modulation in Short-Period Superlattices Using Position-Sensitive X-Ray Detection

    SciTech Connect

    Ahrenkiel, S.P.; Follstaedt, D.M.; Lee, S.R.; Millunchick, J.M.; Norman, A.G.; Reno, J.L.; Twesten, R.D.

    1998-11-10

    Epitaxial growth of AlAs-InAs short-period superlattices on (001) InP can lead to heterostructures exhibiting strong, quasi-periodic, lateral modulation of the alloy composition; transverse satellites arise in reciprocal space as a signature of the compositional modulation. Using an x-ray diffractometer equipped with a position-sensitive x-ray detector, we demonstrate reciprocal-space mapping of these satellites as an efficient, nondestructive means for detecting and characterizing the occurrence of compositional modulation. Systematic variations in the compositional modulation due to the structural design and the growth conditions of the short-period superlattice are characterized by routine mapping of the lateral satellites. Spontaneous compositional modulation occurs along the growth front during molecular-beam epitaxy of (AlAs) (InAs)n short-period superlattices. The modulation is quasi-periodic and forms a lateral superlattice superimposed on the intended SPS structure. Corresponding transverse satellites arise about each reciprocal lattice point, and x-ray diffraction can be routinely used to map their local reciprocal-space structure. The integrated intensity, spacing, orientation, and shape of these satellites provide a reliable means for nondestructively detecting and characterizing the compositional modulation in short-period superlattices. The analytical efficiency afforded by the use of a PSD has enabled detailed study of systematic vacations in compositional modulation as a function of the average composition, the period, and the growth rate of the short- period superlattice

  5. 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.

  6. Wedge-and-strip anodes for centroid-finding position-sensitive photon and particle detectors

    NASA Technical Reports Server (NTRS)

    Martin, C.; Jelinsky, P.; Lampton, M.; Malina, R. F.

    1981-01-01

    The paper examines geometries employing position-dependent charge partitioning to obtain a two-dimensional position signal from each detected photon or particle. Requiring three or four anode electrodes and signal paths, images have little distortion and resolution is not limited by thermal noise. An analysis of the geometrical image nonlinearity between event centroid location and the charge partition ratios is presented. In addition, fabrication and testing of two wedge-and-strip anode systems are discussed. Images obtained with EUV radiation and microchannel plates verify the predicted performance, with further resolution improvements achieved by adopting low noise signal circuitry. Also discussed are the designs of practical X-ray, EUV, and charged particle image systems.

  7. New data collection subsystem for the position sensitive detectors of the KSN-2 neutron diffractometer.

    PubMed

    Dráb, Martin

    2010-01-01

    Project INDECS (integrated neutron diffraction experiment control system) is a newly developed software system created for the purpose of data acquisition from, and controlling of, the KSN-2 neutron diffractometer equipped with PSDs. For the actual data acquisition and initial data analysis of the raw sampled signals a special modular structure called the PSD acquisition path (or PSDAP) was designed. PSDAP also allows to store the raw data, which can be later replayed without actually performing the experiment again. PMID:19822436

  8. Micro-channel plate photon detector studies for the TORCH detector

    NASA Astrophysics Data System (ADS)

    Castillo García, L.; Brook, N.; Cowie, E. N.; Cussans, D.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Harnew, N.; Piedigrossi, D.; Van Dijk, M.

    2015-07-01

    The Time Of internally Reflected Cherenkov light (TORCH) detector is under development. Charged particle tracks passing through a 1 cm plate of quartz will generate the Cherenkov photons, and their arrival will be timed by an array of micro-channel plate photon detectors. As part of the TORCH R&D studies, commercial and custom-made micro-channel plate detectors are being characterized. The final photon detectors for this application are being produced in a three-phase program in collaboration with industry. Custom-made single-channel devices with extended lifetime have been manufactured and their performance is being systematically investigated in the laboratory. Optical studies for the preparation of beam and laboratory tests of a TORCH prototype are also underway.

  9. 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.

  10. 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.

  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. 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

  14. Study and application of hole structures as gas gain devices for two dimensional high rate X-ray detectors

    NASA Astrophysics Data System (ADS)

    Sarvestani, A.; Besch, H. J.; Junk, M.; Meißner, W.; Sauer, N.; Stiehler, R.; Walenta, A. H.; Menk, R. H.

    1998-02-01

    Recent developments in hole structures seem to be a promising enrichment for gas-filled photon counters. Up to now, only few investigations of the performance and limitations of these structures have been carried out. In this work a micro-hole structure is presented together with investigations focused on applications with position sensitive pressurized X-ray detectors for synchrotron radiation. In particular, position resolution, gas gain, rate capability, drift field influence and pressure behavior have been studied. In addition, first two dimensional X-ray images have been measured using a gas amplifying micro-hole structure in combination with a resistive position encoding structure. Since different types of hole structures were tested, predictions of structure geometries adapted for specific applications were carried out.

  15. 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

  16. 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.

  17. 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.

  18. Study of a nTHGEM-based thermal neutron detector

    NASA Astrophysics Data System (ADS)

    Li, Ke; Zhou, Jian-Rong; Wang, Xiao-Dong; Xiong, Tao; Zhang, Ying; Xie, Yu-Guang; Zhou, Liang; Xu, Hong; Yang, Gui-An; Wang, Yan-Feng; Wang, Yan; Wu, Jin-Jie; Sun, Zhi-Jia; Hu, Bi-Tao

    2016-07-01

    With new generation neutron sources, traditional neutron detectors cannot satisfy the demands of the applications, especially under high flux. Furthermore, facing the global crisis in 3He gas supply, research on new types of neutron detector as an alternative to 3He is a research hotspot in the field of particle detection. GEM (Gaseous Electron Multiplier) neutron detectors have high counting rate, good spatial and time resolution, and could be one future direction of the development of neutron detectors. In this paper, the physical process of neutron detection is simulated with Geant4 code, studying the relations between thermal conversion efficiency, boron thickness and number of boron layers. Due to the special characteristics of neutron detection, we have developed a novel type of special ceramic nTHGEM (neutron THick GEM) for neutron detection. The performance of the nTHGEM working in different Ar/CO2 mixtures is presented, including measurements of the gain and the count rate plateau using a copper target X-ray source. A detector with a single nTHGEM has been tested for 2-D imaging using a 252Cf neutron source. The key parameters of the performance of the nTHGEM detector have been obtained, providing necessary experimental data as a reference for further research on this detector. Supported by National Natural Science Foundation of China (11127508, 11175199, 11205253, 11405191), Key Laboratory of Neutron Physics, CAEP (2013DB06, 2013BB04) and CAS (YZ201512)

  19. 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

  20. 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.

  1. 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.

  2. 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.; Gunapala, Sarath D.

    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.

  3. Advanced Two-Dimensional Thermal Neutron Detectors for Scattering Studies

    SciTech Connect

    Fried, J.; Harder, J.; Mahler, G.J.; Makowiecki, D.S.; Mead, J.A.; Radeka, V.; Schaknowski, N.A.; Smith, G.C.; Yu, B.

    2002-11-18

    Advances in neutron scattering studies will be given a large boost with the advent of new spallation and reactor sources at present under consideration or construction. An important element for future experiments is a commensurate improvement in neutron detection techniques. At Brookhaven, a development program is under way for greatly increasing the angular coverage, rate capability and resolution of detectors for scattering studies. For example, a curved detector with angular coverage of 120{sup o} by 15{sup o} has recently been developed for protein crystallography at a spallation source. Based on neutron detection using {sup 3}He, the detector has the following major, new attributes: eight identical proportional wire segments operating in parallel, a single gas volume with seamless readout at segment boundaries, parallax errors eliminated in the horizontal plane by the detector's appropriate radius of curvature, high-throughput front-end electronics, position decoding based on high performance digital signal processing. The detector has a global rate capability greater than 1 million per second, position resolution less than 1.5 mm FWHM, timing resolution about 1 {micro}s, efficiency of 50% and 90% at 1{angstrom} and 4 {angstrom} respectively, and an active area 1.5 m x 20 cm.

  4. 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.

  5. Charge Detector Study for a Thin Sampling Calorimeter for ACCESS

    NASA Technical Reports Server (NTRS)

    Lee, Jeongin; Adams, James H., Jr.

    2000-01-01

    Advanced Cosmic ray Composition Experiment for Space Station (ACCESS) is a NASA's new mission concept that is now being studied. The scientific objective is to measure cosmic ray elemental energy spectra in the energy range from I TeV up to 1000 TeV. ACCESS will carry two instruments and measure the energy and charge of incoming particles. One of these will be a calorimeter with a charge detector. The charge detector will see not only signals from the incident cosmic rays but also signals from radiation backscattered from the calorimeter. In that case, bias information on particle identification is unavoidable. This study shows how much the charge detector will be affected by backscatter and how it can be designed with a minimized effect.

  6. Luminosity measurement method for the LHC: The detector requirement studies

    NASA Astrophysics Data System (ADS)

    Krasny, M. W.; Chwastowski, J.; Cyz, A.; Słowikowski, K.

    2013-11-01

    In our earlier paper [1] we have proposed a new luminosity measurement method for the LHC collider. It is based on the detection of lepton pairs produced in the peripheral collisions of the LHC beam particles and allows to reach better than 1% accuracy of the theoretical control of the event rate. In order to implement this method a new, specialized luminosity detector must be incorporated within the fiducial volume of one of the existing LHC detectors. In this paper the requirement studies for such a detector are presented. They are driven, almost exclusively, by its capacity to identify, within the level 1 trigger latency of the host detector, the bunch crossings with exclusive, coplanar pairs of opposite charge particles. It is shown that a tracking detector with the azimuthal hit resolution of 2 mrad allows us to reduce the rate of background events to the requisite O(1 kHz) level while retaining a sufficiently large fraction of the signal events for the precise luminosity measurement.

  7. 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.

  8. 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.

  9. 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

  10. Application of a One-Dimensional Position Sensitive Chamber on Synchrotron Radiation

    NASA Astrophysics Data System (ADS)

    Qi, Huirong; Liu, Mei

    2014-02-01

    In the last few years, wire chambers have been frequently used for X-ray detection because of their low cost, large area and reliability. X-ray diffraction is an irreplaceable method for powder crystal lattice measurements. A one-dimensional single-wire chamber has been developed in our lab to provide high position resolution for powder diffraction experiments using synchrotron radiation. There are 200 readout strips of 0.5 mm width with a pitch of 1.0 mm in the X direction, and the working gas is a mixture of Ar and CO2 (90/10). The one-dimensional position of the original ionization point is determined by the adjacent strip's distribution information using the center of gravity method. Recently, a study of the detector's performance and diffraction image was completed at the 1W1B laboratory of the Beijing Synchrotron Radiation Facility (BSRF) using a sample of SiO2. Most of the relative errors between the measured values of diffraction angles and existing data were less than 1%. The best position resolution achieved for the detector in the test was 71 μm (σ value) with a 20 μm slit collimator. Finally, by changing the detector height in incremental distances from the center of the sample, the one-dimensional detector achieved a two-dimensional diffraction imaging function, and the results are in good agreement with standard data.

  11. Calculation of track and vertex errors for detector design studies

    SciTech Connect

    Harr, R.

    1995-06-01

    The Kalman Filter technique has come into wide use for charged track reconstruction in high-energy physics experiments. It is also well suited for detector design studies, allowing for the efficient estimation of optimal track covariance matrices without the need of a hit level Monte Carlo simulation. Although much has been published about the Kalman filter equations, there is a lack of previous literature explaining how to implement the equations. In this paper, the operators necessary to implement the Kalman filter equations for two common detector configurations are worked out: a central detector in a uniform solenoidal magnetic field, and a fixed-target detector with no magnetic field in the region of the interactions. With the track covariance matrices in hand, vertex and invariant mass errors are readily calculable. These quantities are particularly interesting for evaluating experiments designed to study weakly decaying particles which give rise to displaced vertices. The optimal vertex errors are obtained via a constrained vertex fit. Solutions are presented to the constrained vertex problem with and without kinematic constraints. Invariant mass errors are obtained via propagation of errors; the use of vertex constrained track parameters is discussed. Many of the derivations are new or previously unpublished.

  12. 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.

  13. 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. PMID:21839459

  14. 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.

  15. 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.

  16. 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.

  17. Using Berrys phase for position-sensitive acoustical and stress detection

    NASA Astrophysics Data System (ADS)

    Kuzyk, Mark G.

    2002-10-01

    Berry showed that a quantum system, upon an excursion around a closed path in phase space, can lead to a geometric phase. The polarization state of light in a fiber is a classical analog that is called the Pancharantnam phase. While most experiments have focused on esoteric issues, I show that, in theory, Berrys phase (or Pancharantnams phase) can be used to make a position-sensitive acoustical or stress sensor. 2002 Optical Society of America

  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. 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.

  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. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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).

  6. GaN UV detectors for protein studies

    NASA Astrophysics Data System (ADS)

    Grant, J.; Bates, R.; Cunningham, W.; Blue, A.; Melone, J.; McEwan, F.; Manolopoulos, S.; O'Shea, V.

    2006-07-01

    GaN and its ternary alloy AlGaN have been investigated as UV detector materials for applications in protein structure studies. Interdigitated metal-semiconductor-metal (MSM) finger photodiodes, with finger spacings/widths of 5 and 10 μm, were successfully fabricated on six different GaN/AlGaN materials. Current-Voltage ( I- V) characteristics and spectral response measurements were made on completed devices. The results showed negligible difference in performance between the 5 μm finger spacing/width diode design and the 10 μm finger spacing/width diode design. Using these results, a 46 channel diode array, with a finger spacing/width of 10 μm, was successfully fabricated on 2.5 μm thick epitaxial GaN. This 46 channel diode array will be used in a protein structure experiment at the Daresbury SRS.

  7. 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.

  8. 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.

  9. 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.

  10. 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%.

  11. 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.

  12. 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.

  13. The Zero-Degree Detector system for fragmentation studies

    NASA Astrophysics Data System (ADS)

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

    2007-08-01

    The measurement of nuclear fragmentation cross-sections requires the detection and identification of individual projectile fragments. If light and heavy fragments are recorded in the same detector, it may be impossible to distinguish the signal from the light fragment. To overcome this problem, we have developed the Zero-degree Detector System (ZDDS). 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.

  14. 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.

  15. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    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 um, 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.

  17. 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.

  18. Electron-beam studies of Schottky-barrier detector surfaces

    NASA Technical Reports Server (NTRS)

    Peckerar, M. C.

    1973-01-01

    Review of the surface anomalies occurring in Schottky-barrier particle detectors identifiable by means of an electron beam technique employed by Czaja (1965) for analyzing defects in diode structures. The technique is shown to make possible the detection and identification of the following anomalies: (1) chemical contamination of the detector surface; (2) mechanical damage of the wafer substrates; (3) damage introduced in semiconductor surface preparation; (4) radiation damage; and (5) defective surface metallization.

  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. 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).

  1. 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.

  2. Imaging results and TOF studies with axial PET detectors

    NASA Astrophysics Data System (ADS)

    Joram, Christian

    2013-12-01

    We have developed a fully operational PET demonstrator setup which allows true 3D reconstruction of the 511 keV photons and therefore leads to practically parallax free images. The AX-PET concept is based on thin 100 mm long scintillation crystals (LYSO), axially oriented and arranged in layers around the field of view. Layers of wavelength shifting plastic strips mounted in between the crystal layers give the axial coordinate. Both crystals and WLS strips are individually read out by G-APD (SiPM) photodetectors. The fully scalable concept overcomes the dilemma of sensitivity versus spatial resolution which is inherent to classical PET designs. A demonstrator set-up based on two axial modules was exhaustively characterized using point-like sources, phantoms filled with radiotracer and finally rats and a mouse. The results entirely meet the performance expectations (<2 mm FWHM in all three coordinates over the complete field of view) and also demonstrated the ability to include Compton interactions (inter-crystal scatter) in the reconstruction without noticeable performance loss. Our recent studies focus on a TOF extension of the AX-PET concept making use of the novel digital SiPM detectors by Philips. After reproducing comparable energy and spatial resolution on a small digital AX-PET set-up with 100 mm long crystals, we demonstrated a coincidence resolving time of about 210 ps FWHM.

  3. Performance studies of a Micromegas detector with a pad readout geometry

    NASA Astrophysics Data System (ADS)

    Düdder, A.; Lin, T.-H.; Neuhaus, F.; Schott, M.; Valderanis, C.

    2016-07-01

    The results of several performance studies of two prototype Micromegas pad detectors with two different coupling implementations between the resistive and the readout layer are presented. Both prototype detectors have an active area of 10 × 10cm2 and comprise 500 pads with a size of 5 × 4mm2. The first detector has a capacitive coupling between the resistive and the readout layer, as it is well known from Micromegas detectors with a strip readout. The second detector implements a resistive coupling between each readout pad and the resistive layer on top of it with a resistivity of 5 MΩ. In particular, the size of reconstructed charge clusters in both detector types is discussed and compared here for different drift- and amplification voltages.

  4. 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.

  5. 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.

  6. Study of aging of nuclear detector based on n-silicon/copper phthalocyanine heterojunction

    SciTech Connect

    Ray, A.; Gupta, S. K.

    2013-02-05

    Nuclear detectors based on n-silicon/copper-phthalocyanine (CuPc) heterojunction were fabricated using thermally evaporated CuPc thin film. These detectors exhibited stable electrical and {alpha}-particle characteristics for prolonged periods of time under ordinary laboratory conditions and also exposing to {alpha}- particles (during {alpha}- spectroscopic measurements). The electrical and alpha particle characteristics of these detectors were studied after a long gap of 3 - 5 years and the best result obtained from one detector (five year old) is reported here. Degradation in electrical and alpha particle characteristics were not found to be very significant over the period.

  7. 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.

  8. Preliminary design study of astronomical detector cooling system

    NASA Technical Reports Server (NTRS)

    Norman, R. H.

    1976-01-01

    The preliminary design of an astronomical detector cooling system for possible use in the NASA C-141 Airborne Infrared Observatory is presented. The system consists of the following elements: supercritical helium tank, Joule-Thomson supply gas conditioner, Joule-Thomson expander (JTX), optical cavity dewar, optical cavity temperature controller, adjustable J-T discharge gas pressure controller, and vacuum pump.

  9. 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)

  10. 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

  11. Semiconductor detectors for Compton imaging in nuclear medicine

    NASA Astrophysics Data System (ADS)

    Harkness, LJ; Judson, D. S.; Kennedy, H.; Sweeney, A.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Nolan, P. J.; Sampson, J. A.; Burrows, I.; Groves, J.; Headspith, J.; Lazarus, I. H.; Simpson, J.; Bimson, W. E.; Kemp, G. J.

    2012-01-01

    An investigation is underway at the University of Liverpool to assess the suitability of two position sensitive semiconductor detectors as components of a Compton camera for nuclear medical imaging. The ProSPECTus project aims to improve image quality, provide shorter data acquisition times and lower patient doses by replacing conventional Single Photon Emission Computed Tomography (SPECT) systems. These mechanically collimated systems are employed to locate a radioactive tracer that has been administered to a patient to study specifically targeted physiological processes. The ProSPECTus system will be composed of a Si(Li) detector and a High Purity Germanium (HPGe) detector, a configuration deemed optimum using a validated Geant4 simulation package. Characterising the response of the detectors to gamma irradiation is essential in maximising the sensitivity and image resolution of the system. To this end, the performance of the HPGe ProSPECTus detector and a suitable Si(Li) detector has been assessed at the University of Liverpool. The energy resolution of the detectors has been measured and a surface scan of the Si(Li) detector has been performed using a finely collimated 241Am gamma ray source. Results from the investigation will be presented.

  12. 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

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

    PubMed

    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 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

  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. High-resolution detectors for medical applications and synchrotron radiation research

    NASA Astrophysics Data System (ADS)

    Babichev, E. A.; Baru, S. E.; Grigoriev, D. N.; Groshev, V. R.; Leonov, V. V.; Papushev, P. A.; Porosev, V. V.; Savinov, G. A.; Shayakhmetov, V. R.; Shekhtman, L. I.; Tikhonov, Yu. A.; Ukraintsev, Yu. G.; Yurchenko, Yu. B.

    2011-02-01

    In the present report, we summarize our experience in the development of high-resolution position sensitive gas detectors for medicine and synchrotron radiation experiments at Budker Institute of Nuclear Physics for the last years. We have designed several versions of Multistrip Ionisation Chambers with a channel pitch varying from 0.4 down to 0.1 mm. The high quantum efficiency (>65%) of these detectors allow its application in high quality diagnostic imaging. The detector with 0.1 mm strip pitch and 20 atm pressure of Xe demonstrates the best possible DQE and spatial resolution for gaseous detectors in a wide range of X-ray energies. Additionally, the initial results of feasibility study of the detector for beam position monitoring for Heavy Ion Therapy System are presented too.

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

    SciTech Connect

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

    2013-02-15

    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%)CF{sub 4}, at atmospheric pressure, in a stable condition at a gain of around 10{sup 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.

  17. 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.

  18. 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.

  19. Shielding optimization studies for the detector systems of the Superconducting Super Collider

    SciTech Connect

    Slater, C.O.; Lillie, R.A.; Gabriel, T.A.

    1994-09-01

    Preliminary shielding optimization studies for the Superconducting Super Collider`s Solenoidal Detector Collaboration detector system were performed at the Oak Ridge National Laboratory in 1993. The objective of the study was to reduce the neutron and gamma-ray fluxes leaving the shield to a level that resulted in insignificant effects on the functionality of the detector system. Steel and two types of concrete were considered as components of the shield, and the shield was optimized according to thickness, weight, and cost. Significant differences in the thicknesses, weights, and costs were noted for the three optimization parameters. Results from the study are presented.

  20. Comparative study of ionization chamber detectors vis-a-vis a CCD detector for dispersive XAS measurement in transmission geometry

    SciTech Connect

    Poswal, A. K.; Agrawal, A.; Bhattachryya, D.; Jha, S. N.; Sahoo, N. K.

    2013-02-05

    We have designed and fabricated parallel plate ionization chamber detectors and voltage vs. current characteristics (V-I curve) of the detectors were recorded with synchrotron radiation to qualify for use in X-ray Absorption Spectroscopy (XAS) measurements. After qualifying the ionization chambers, the detectors were used in the dispersive EXAFS beamline (BL-08) at INDUS-2 SRS in Turbo-XAS geometry. Using the same setup and under the same setting, XAS spectra were also recorded with a CCD detector and the observation on relative performance of the ionization chamber vis-a-vis the CCD detector is presented in this paper.

  1. 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.

  2. A Monte Carlo simulation and deconvolution study of detector response function for small field measurements

    NASA Astrophysics Data System (ADS)

    Feng, Yuntao

    Different types of radiation detectors are routinely used for the dosimetry of photon beams. Finite detector sizes have certain effects to the broadening of the measured beam penumbra. The problem is more important in small field measurement, such as stereotactic radiosurgery, small beamlet IMRT, etc. The dosimetry associated with small fields is very difficult because of the steep dose gradients and the lack of lateral electronic equilibrium conditions that complicate the interpretation of the dose measurement. Many Researchers have investigated this problem from different points of view utilizing, for example, extrapolation method, analytical method. But their studies were all measurements based. In this study, we investigated the problem using Monte Carlo simulation method. Compared with practical measurements, the advantages of using Monte Carlo simulation are: (1) Simulation can be performed in a scenario where radiation dosimetry is technically difficult or even impossible to accomplish; (2) Possible systematic errors, e.g., setup errors, reading errors, can be eliminated; (3) Simulation of radiation detectors which are not readily available allowed the study of a wider range of detector sizes. In this study we used Monte Carlo methods to develop and apply detector response functions (DRFs) for three types of clinically available radiation detectors and two theoretical detectors. Detector response functions were determined by deconvolving known values of input (simulated true data from Monte Carlo simulation) and output (simulated empirical data from Monte Carlo simulation or empirical data from radiation dosimetry). Deconvolved detector response functions were applied to typical stereotactic radiosurgery fields to obtain the true beam profile. This application was then benchmarked by both Monte Carlo simulation method and dosimetry methods, which include diode dosimetry, radiographic film dosimetry, and Gafchromic film dosimetry. The results of this research

  3. Position sensitive anodes for MCP read-out using induced charge measurement

    NASA Astrophysics Data System (ADS)

    Jagutzki, O.; Lapington, J. S.; Worth, L. B. C.; Spillman, U.; Mergel, V.; Schmidt-Böcking, H.

    2002-01-01

    We investigate the method of an indirect detection of a MCP charge avalanche projected onto a resistive layer (G. Battistoni, et al., Nucl. Instr. and Meth., 202 (1982) 459). If the sheet resistance is favourable one can detect the charge cloud by the capacitive coupling to an anode structure a few millimetres behind the layer. The anode structure can be, for example, a wedge-and-strip electrode pattern (M. Unverzagt, Diplomarbeit, Universität Frankfurt 1992, private communication) as it is used for directly collecting the electron avalanche from a MCP. Detection of the induced charge is beneficial in several respects. Firstly, image distortions produced by secondary electron mediated charge redistribution are eliminated. Secondly, the noise component due to quantized charge collection, commonly referred to as partition noise, is not present. In addition, the dielectric substrate can function both as an element of the vacuum enclosure and HV insulator, making the electrical connections easily accessible and the pattern operable at ground potential, independently of detector operating voltages. This technique can be used to simplify the electronic design requirements where varying high voltages are required at the detector input face such as plasma analysers, etc. It also has application in the manufacture of intensifier tubes (J. Barnstedt, M. Grewing, Nucl. Instr. and Meth., these proceedings) where the inclusion of a readout pattern inside the intensifier body with associated electrical feed-throughs can prove problematic. We will present data on the performance of such detection geometries using several types of charge division anode, and discuss the advantages compared with the "traditional" charge collecting method.

  4. 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).

  5. Study and optimization of the spatial resolution for detectors with binary readout

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    Using simulations and analytical approaches, we have studied single hit resolutions obtained with a binary readout, which is often proposed for high granularity detectors to reduce the generated data volume. Our simulations considering several parameters (e.g. strip pitch) show that the detector geometry and an electronics parameter of the binary readout chips could be optimized for binary readout to offer an equivalent spatial resolution to the one with an analog readout. To understand the behavior as a function of simulation parameters, we developed analytical models that reproduce simulation results with a few parameters. The models can be used to optimize detector designs and operation conditions with regard to the spatial resolution.

  6. 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.

  7. Study of the high rate performance of the MicroCAT detector

    NASA Astrophysics Data System (ADS)

    Sarvestani, A.; Besch, H. J.; Menk, R. H.; Pavel, N.; Sauer, N.; Strietzel, C.; Walenta, A. H.

    1999-08-01

    The recently developed micro-pattern detectors (CAT, MIRCOMEGAS, GEM, MicroCAT, etc.) are a very promising enrichment for applications with gaseous x-ray detectors. In order to determine their suitability for imaging measurements using strong x-ray sources, in particular synchrotron light sources, the high rate capability has to be considered carefully. Here, a study of the high rate performance of the MicroCAT detector is presented, focusing on the four major high rate parameters: dead time effects, space charge effects, gas gain stability and rate-induced breakdowns.

  8. A 140-element Ge detector fabricated using amorphous Ge blocking contacts

    SciTech Connect

    Luke, P.N.; Pehl, R.H.; Dilmanian, F.A.

    1993-10-01

    A 140-element position-sensitive Ge detector has been fabricated as the prototype detector for the development of a monochromatic computed tomography system using synchrotron radiation. The detector was made in very few processing steps that included the use of amorphous Ge blocking contacts. The fabrication process and the results of testing the detector are described.

  9. 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

  10. [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. PMID:24941771

  11. [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.

  12. X-ray tests of a microchannel plate detector and amorphous silicon pixel array readout for neutron radiography

    NASA Astrophysics Data System (ADS)

    Ambrosi, R. M.; Street, R.; Feller, B.; Fraser, G. W.; Watterson, J. I. W.; Lanza, R. C.; Dowson, J.; Ross, D.; Martindale, A.; Abbey, A. F.; Vernon, D.

    2007-03-01

    High-performance large area imaging detectors for fast neutrons in the 5-14 MeV energy range do not exist at present. The aim of this project is to combine microchannel plates or MCPs (or similar electron multiplication structures) traditionally used in image intensifiers and X-ray detectors with amorphous silicon (a-Si) pixel arrays to produce a composite converter and intensifier position sensitive imaging system. This detector will provide an order of magnitude improvement in image resolution when compared with current millimetre resolution limits obtained using phosphor or scintillator-based hydrogen rich converters. In this study we present the results of the initial experimental evaluation of the prototype system. This study was carried out using a medical X-ray source for the proof of concept tests, the next phase will involve neutron imaging tests. The hybrid detector described in this study is a unique development and paves the way for large area position sensitive detectors consisting of MCP or microsphere plate detectors and a-Si or polysilicon pixel arrays. Applications include neutron and X-ray imaging for terrestrial applications. The technology could be extended to space instrumentation for X-ray astronomy.

  13. 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

  14. 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

    2014-12-01

    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 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.

  15. 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.

  16. 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.

  17. Study of timing performance of silicon photomultiplier and application for a Cherenkov detector

    NASA Astrophysics Data System (ADS)

    Ahmed, G. S. M.; Bühler, P.; Marton, J.; Suzuki, K.

    2011-02-01

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

  18. 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.

  19. Improved Position Calibration for the FAUST Detector

    NASA Astrophysics Data System (ADS)

    Bakhtiari, Layla; Heilborn, Lauren; Cammarata, Paul; McIntosh, Alan; Youngs, Mike; Chapman, Matthew; Yennello, Sherry

    2013-10-01

    The Forward Array Using Silicon Technology (FAUST), is a detector array used to measure charged particles resulting from heavy-ion reactions. Studying multifragmentation in these reactions can give insight into the Equation of State of nuclear matter, which is important for understanding concepts in astrophysics such as the formation of the atomic elements, neutron star development, and supernovae behavior. In order to characterize the events more fully, the current silicon detectors will be replaced with position sensitive Dual-Axis Dual-Lateral (DADL) detectors. To maximize the use of these new detectors, a procedure to perform position and energy calibrations with the fully assembled array had to be developed. Testing of the mask will be performed in two stages: a preliminary test with a single ring of the array, followed by a comprehensive test with all rings of FAUST. The new calibration procedure, including the custom designed mask and the in-beam testing results of a single ring, will be presented. This work was supported by the DOE and NSF-REU Program.

  20. A transparent anode array detector for 3D atom probes

    SciTech Connect

    Miller, M.K.

    1998-02-01

    In a three dimensional atom probe, the identity and spatial coordinates of the atoms field evaporated from the specimen are determined. Their identity is calculated from the flight time from the specimen to the single atom detector. The x and y coordinates of the atom in the specimen are determined from the coordinates of its impact position on the position-sensitive detector and the z coordinate is determined from its position in the evaporation sequence. These data may then be reconstructed to visualize and quantify the distribution of all the elements in the specimen. Several types of position-sensitive detectors have been used including a wedge-and-strip detector (position- sensitive atom probe), a 10 by 10 array of anodes (tomographic atom probe), and a gateable CCD camera (optical atom probe). The wedge-and strip and the CCD camera detectors both suffer from the limitation that if more than one atom strikes the detector on a field evaporation pulse then the impact positions cannot be determined in many cases. In order to minimize this limitation, Cerezo et al. have developed a dual detector system (optical position-sensitive atom probe) that uses both an 8 by 10 multianode array and an intensified CCD camera. This dual detector configuration requires a beam splitter which reduces the signal intensity reaching the detectors and two independent detection systems both with image intensifiers. In this paper, an improved version of this detection system that combines these two systems into one is presented.

  1. Feasibility studies of the self-TOF detector for high-energy neutron measurements in shielding experiments

    NASA Astrophysics Data System (ADS)

    Sasaki, M.; Nakao, M.; Shibata, T.; Nakao, N.; Nakamura, T.

    2000-05-01

    The feasibility of a new type of neutron detector was studied. The detector consists of a radiator, a start counter and a stop counter. The radiator is composed of 20 thin plastic-scintillation detectors and the stop counter is segmented into nine plastic-scintillation detectors. Neutrons impinging on the radiator emit charged particles. The time of flight of protons emitted at a forward angle is measured using the start and stop counters, therefore, we call the detector the "self-TOF detector". The proton time-of-flight spectrum is converted to the energy spectrum of neutrons using a measured response function. The basic properties of the detector, such as detection efficiency, signal-to-noise ratio, particle identification capability, and energy resolution, were studied.

  2. 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.

  3. Further studies of single-sided charge-sharing CZT strip detectors

    NASA Astrophysics Data System (ADS)

    Donmez, Burcin; Macri, John R.; McConnell, Mark L.; Ryan, James M.; Widholm, Mark; Narita, Tomohiko; Hamel, Louis-Andre

    2005-08-01

    We report progress in the study of a thick CZT strip detector module designed to perform gamma-ray spectroscopy and 3-D imaging. We report preliminary performance measurements of 7.5 mm thick single-sided charge-sharing strip detector prototype devices. This design features both row and column contacts on the anode surface. This electron-only approach addresses problems associated with poor hole transport in CZT that limit the thickness and energy range of double-sided strip detectors. This work includes laboratory and simulation studies aimed at developing compact, efficient, detector modules for 0.05 to 1 MeV gamma measurements while minimizing the number and complexity of the electronic readout channels. This is particularly important in space-based coded aperture and Compton telescope instruments that require large area, large volume detector arrays. Such arrays will be required for the NASA Black Hole Finder Probe (BHFP)and Advanced Compton Telescope (ACT). This new design requires an anode pattern with contacts whose dimensions and spacing are roughly the size of the ionization charge cloud. The first prototype devices have 125 μm anode contacts on 225 μm pitch. Our results demonstrate the principle of operation but suggest that even finer anode contact feature sizes will be necessary to achieve the desired performance.

  4. Mechanistic study and optimization of a hydrogen atmosphere flame ionization detector

    SciTech Connect

    Lillie, C.H.

    1985-01-01

    A residual gas analyzer was modified to study ions produced by flames similar to those used in the organometallic and organosilicon selective hydrogen atmosphere flame ionization detectors, HAFID and HAFID-Si, respectively. Flame ions traveled from 1 to 7 cm at atmospheric pressure prior to entering the vacuum chamber. The ions were then extracted and focused using an Einzel lens system into a quadrupole mass spectrometer. The mass spectrometry system was calibrated using the ions produced by a radioactive Ni-63 foil which had nitrogen gas blown over it. Optimization of the system was accomplished by varying parameters while the Ni-63 foil was the ionizing source and then with a hydrogen in air diffusion flame. The mass spectrum from a flame similar in composition to that used in the gas chromatographic flame ionization detector was compared to literature spectra to validate the results. Characterization studies of the HAFID indicated a linear range of two orders of magnitude for organics with a minimum detectable amount of 500 ng for tetradecane. An equal per carbon response pattern similar to that observed in the FID was observed with the HAFID for a homologous n-alkane series. A new detector design that allows the collector to jet tip height to be varied while the detector flame is burning was utilized in the simplex optimization of the detector. A computer program that utilizes variable sized steps in the simplex was developed to determine the next set of conditions to be tested and to determine when the optimum had been reached. A mechanism was developed to account for the selective response of the organometallic and organosilicon selective detectors. The mechanisms were based on the results of the mass spectrometric studies, characterization studies and thermodynamic data obtained from the literature.

  5. 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)

  6. [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.

  7. Study of Quasi-Elastic Scattering in the NOnuA Detector Prototype

    NASA Astrophysics Data System (ADS)

    Betancourt, Minerba

    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 off-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. This thesis presents the analysis of the data from two detector configurations, the first configuration collected data from 1e19 protons on target (POT) from April to May 2011 and the second configuration collected data from 1.7e20POT from October 2011 to April 2012. The charged current quasi-elastic muon neutrino events collected with each configuration were analyzed to extract the cross section as a function of energy as well as the single differential cross sections with respect to outgoing muon momentum, outgoing muon angle from the incident neutrino direction; and the momentum dP, and transfer squared of the interaction.

  8. 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.

  9. Characterisation of an AGATA symmetric prototype detector

    NASA Astrophysics Data System (ADS)

    Nelson, L.; Dimmock, M. R.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Nolan, P. J.; Lazarus, I.; Simpson, J.; Medina, P.; Santos, C.; Parisel, C.

    2007-04-01

    The Advanced GAmma Tracking Array (AGATA) symmetric prototype detector has been tested at the University of Liverpool. A 137Ce source, collimated to a 2 mm diameter, was scanned across the front face of the detector and data were acquired utilising digital electronics. Pulse shapes from a selection of well-defined photon interaction positions have been analysed to investigate the position sensitivity of the detector. Furthermore, the application of the electric field simulation software, Multi Geometry Simulation (MGS) to generate theoretical pulse shapes for AGATA detectors has been presented.

  10. Strategy for studying {nu}{sub {mu}} CCQE interactions in the T2K near detector

    SciTech Connect

    Monfregola, L.; Villanueva, A. Cervera; Stamoulis, P.

    2011-11-23

    The T2K (Tokai-to-Kamioka) experiment is a long-baseline neutrino oscillation experiment, currently operating in Japan, aiming at measuring the {theta}{sub 13} mixing angle. It uses an intense off-axis beam of mainly muon neutrinos incident on the Super-Kamiokande detector. The off-axis near detector complex, ND280, can be used to perform charge current quasi-elastic (CCQE) measurements, that define the flux normalization and predict the unoscillated spectrum. The strategy for studying {nu}{sub {mu}} CCQE interactions in the ND280 detector is described, together with the first inclusive charge current results from the first period of T2K operation.

  11. 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.

  12. 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.

  13. A study on the photoresponses in GaAs n-channel optical detectors

    NASA Astrophysics Data System (ADS)

    Wei, C. J.; Klein, H.-J.; Beneking, H.

    1982-09-01

    The behavior of photocarriers in a GaAs planar n-channel device as an optical detector is studied. Computer simulations show that space charges of those photogenerated carriers give rise to a high-gain and high-speed amplification mechanism which results in Gunn oscillations at intense irradiations. Experiments have confirmed these oscillations. The observed results agree with theoretical computations.

  14. 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.

  15. 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.

  16. Advanced far infrared detector and double donor studies in Ge

    SciTech Connect

    Olsen, C.S.

    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.

  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. 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.

  19. Annealing studies of silicon microstrip detectors irradiated at high neutron fluences

    NASA Astrophysics Data System (ADS)

    Miñano, M.; Balbuena, J. P.; García, C.; González, S.; Lacasta, C.; Lacuesta, V.; Lozano, M.; Martí i Garcia, S.; Pellegrini, G.; Ullán, M.

    2008-06-01

    Silicon p-type detectors are being investigated for the development of radiation-tolerant detectors for the luminosity upgrade of the CERN large hadron collider (Super-LHC (sLHC)). Microstrip detectors have been fabricated by CNM-IMB with an n-side read-out on p-type high-resistivity float zone substrates. They have been irradiated with neutrons at the TRIGA Mark II nuclear reactor in Ljubljana. The irradiation fluxes match with the expected doses for the inner tracker at the sLHC (up to 10 16 equivalent 1 MeV neutrons cm -2). The macroscopic properties of the irradiated prototypes after irradiation were characterized at the IFIC-Valencia laboratory. The charge collection studies were carried out by means of a radioactive source setup as well as by an infrared laser illumination. The annealing behavior was studied in detail on a microstrip detector irradiated with a flux of 10 15 equivalent 1 MeV neutrons cm -2. Collected charge measurements were made after accelerated annealing times at 80 °C up to an equivalent annealing time of several years at room temperature. This note reports on the recorded results from the annealing of the irradiated p-type microstrip sensor.

  20. 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. PMID:26906576

  1. 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.

  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. Disentangling detector data in XFEL studies of temporally resolved solution state chemistry.

    PubMed

    Brandt van Driel, Tim; Kjær, Kasper Skov; Biasin, Elisa; Haldrup, Kristoffer; Lemke, Henrik Till; Nielsen, Martin Meedom

    2015-01-01

    With the arrival of X-ray Free Electron Lasers (XFELs), 2D area detectors with a large dynamic range for detection of hard X-rays with fast readout rates are required for many types of experiments. Extracting the desired information from these detectors has been challenging due to unpredicted fluctuations in the measured images. For techniques such as time-resolved X-ray Diffuse Scattering (XDS), small differences in signal intensity are the starting point for analysis. Fluctuations in the total detected signal remain in the differences under investigation, obfuscating the signal. To correct such artefacts, Singular Value Decomposition (SVD) can be used to identify and characterize the observed detector fluctuations and assist in assigning some of them to variations in physical parameters such as X-ray energy and X-ray intensity. This paper presents a methodology for robustly identifying, separating and correcting fluctuations on area detectors based on XFEL beam characteristics, to enable the study of temporally resolved solution state chemistry on the femtosecond timescale.

  4. 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.

  5. Disentangling detector data in XFEL studies of temporally resolved solution state chemistry.

    PubMed

    Brandt van Driel, Tim; Kjær, Kasper Skov; Biasin, Elisa; Haldrup, Kristoffer; Lemke, Henrik Till; Nielsen, Martin Meedom

    2015-01-01

    With the arrival of X-ray Free Electron Lasers (XFELs), 2D area detectors with a large dynamic range for detection of hard X-rays with fast readout rates are required for many types of experiments. Extracting the desired information from these detectors has been challenging due to unpredicted fluctuations in the measured images. For techniques such as time-resolved X-ray Diffuse Scattering (XDS), small differences in signal intensity are the starting point for analysis. Fluctuations in the total detected signal remain in the differences under investigation, obfuscating the signal. To correct such artefacts, Singular Value Decomposition (SVD) can be used to identify and characterize the observed detector fluctuations and assist in assigning some of them to variations in physical parameters such as X-ray energy and X-ray intensity. This paper presents a methodology for robustly identifying, separating and correcting fluctuations on area detectors based on XFEL beam characteristics, to enable the study of temporally resolved solution state chemistry on the femtosecond timescale. PMID:25675434

  6. 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

  7. Study of absolute fast neutron dosimetry using CR-39 track detectors

    NASA Astrophysics Data System (ADS)

    El-Sersy, A. R.

    2010-06-01

    In this work, CR-39 track detectors have extensively been used in the determination of fast neutron fluence-to-dose factor. The registration efficiency, ɛ, of CR-39 detectors for fast neutrons was calculated using different theoretical approaches according to each mode of neutron interaction with the constituent atoms (H, C and O) of the detector material. The induced proton-recoiled showed the most common interaction among the others. The dependence of ɛ on both neutron energy and etching time was also studied. In addition, the neutron dose was calculated as a function of neutron energy in the range from 0.5 to 14 MeV using the values of (d E/d X) for each recoil particle in CR-39 detector. Results showed that the values of ɛ were obviously affected by both neutron energy and etching time where the contribution in ɛ from proton recoil was the most. The contribution from carbon and oxygen recoils in dose calculation was pronounced due to their higher corresponding values of d E/d X in comparison to those from proton recoils. The present calculated fluence-to-dose factor was in agreement with that either from ICRP no. 74 or from TRS no. 285 of IAEA, which reflected the importance of using CR-39 in absolute fast neutron dosimetry.

  8. 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.

  9. Performance of a Ge-microstrip imaging detector and polarimeter.

    PubMed

    Spillmann, U; Bräuning, H; Hess, S; Beyer, H; Stöhlker, Th; Dousse, J-Cl; Protic, D; Krings, T

    2008-08-01

    Using 98% linearly polarized radiation at the European Synchrotron Radiation Facility in Grenoble, the performance of a prototype two-dimensional microstrip Ge(i) detector for x-ray imaging and as a Compton polarimeter has been evaluated. Using the energy and position sensitivity of the detector, the ability to obtain a complete reconstruction of the Compton event has been demonstrated. The modulation coefficient of the polarimeter is in good agreement with the theoretical limit of a perfect detector. PMID:19044330

  10. Performance of a Ge-microstrip imaging detector and polarimeter

    SciTech Connect

    Spillmann, U.; Braeuning, H.; Hess, S.; Beyer, H.; Stoehlker, Th.; Dousse, J.-Cl.; Protic, D.; Krings, T.

    2008-08-15

    Using 98% linearly polarized radiation at the European Synchrotron Radiation Facility in Grenoble, the performance of a prototype two-dimensional microstrip Ge(i) detector for x-ray imaging and as a Compton polarimeter has been evaluated. Using the energy and position sensitivity of the detector, the ability to obtain a complete reconstruction of the Compton event has been demonstrated. The modulation coefficient of the polarimeter is in good agreement with the theoretical limit of a perfect detector.

  11. Low-Energy Study of Gamma-Ray Bursts Using Two BATSE Spectroscopy Detectors

    NASA Technical Reports Server (NTRS)

    Pangia, Michael J.

    2002-01-01

    Gamma-ray bursts (GRBs) are energetic, short-duration emissions of gamma-rays from astronomical sources typically well beyond our galaxy. The Burst and Transient Source Experiment (BATSE) that was onboard NASA's Compton Gamma-Ray Observatory (CGRO) had detected an unprecedented 2704 GRBs during CGRO's nine-year mission. BATSE consisted of eight detector assemblies located at the corners of CGRO to give full sky coverage. Each assembly consisted of two detectors, a Large Area Detector (LAD) and a Spectroscopy Detector (SD). In determining the detail features of GRBs, the degree to which they possess a low-energy component (approx. 10 keV) is of interest. Preece has developed a method to study the low-energy characteristics and concluded that 14% of the 86 bright GRBs they studied had a definite low-energy component, referred to as a low-energy excess. Their study, and the present study as well, needed to use SD data, because it extends down to the low-energy range when operating in a high-gain mode. For their study, low-energy data was used from just one SD. To better quantify the low-energy behavior, this study will consider bursts for which two SDs satisfy the same criteria as used by Preece. The procedure developed by Preece to study the low-energy aspects of GRBs with BATSE data is to fit the data to a representative spectral function. In particular, two components are used, one corresponding to the low-energy component, and another representing the main part of the spectrum. The low-energy function used is the optically thin thermal bremsstrahlung (OTTB) model.

  12. Body contour 180 degrees pinhole SPET with or without tilted detector: a phantom study.

    PubMed

    Seret, Alain; Flérès, David; Firket, Olivier; Defrise, Michel

    2003-09-01

    This study investigated the feasibility of ordered subsets expectation maximisation (OS-EM) reconstruction of 180 degrees pinhole single-photon emission tomography (SPET) acquired in body contour mode (variable distance between the detector and the axis of rotation for each projection) with or without a tilted detector head. Four non-circular orbits were designed bearing in mind the rotation radius and tilt angle values of previous pinhole SPET acquisitions in patients with circular orbits. The reconstructions were performed using a dedicated OS-EM algorithm. Reconstructed images of line and uniformity phantoms showed that the spatial and uniformity characteristics of the radioactive objects were preserved. In comparison with the circular orbits, the non-circular orbits allowed only a moderate gain (maximum 10%) in resolution. However, body contour pinhole SPET would significantly facilitate the camera set-up and in this way should decrease the camera set-up time, which is an important parameter in patient studies.

  13. 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.

  14. Study of the muon-induced neutron background with the LVD detector

    SciTech Connect

    Menghetti, H.; Selvi, M.

    2005-09-08

    High energy neutrons, generated as a product of cosmic muon interaction in the rock or in the detector passive material, represent the most dangerous background for a large list of topics like reactor neutrino studies, the search for SN relic neutrinos, solar antineutrinos, etc.Up to now there are few measurements of the muon-produced neutron flux at large depth underground. Moreover it is difficult to reproduce the measured data with Monte Carlo simulation because of the large uncertainties in the neutron production and propagation models.We present here the results of such a measurement with the LVD detector, which is well suited for the detection of neutrons produced by cosmic-ray muons, reporting the neutron flux at various distances from the muon track, for different neutron energies (E > 20 MeV) and as a function of the muon track length in scintillator.

  15. Study of elastic proton-proton scattering with the STAR detector at RHIC

    NASA Astrophysics Data System (ADS)

    Sikora, Rafal

    2015-09-01

    The STAR detector at the Relativistic Heavy Ion Collider (RHIC) is equipped with system of dedicated Silicon Strip Detectors housed inside Roman Pot vessels, allowing to detect protons scattered at small angles. Data from polarized proton-proton collisions at center-of-mass system (c.m.s.) energy √s = 200 GeV collected with special settings of RHIC magnet lattice (β * = 22 m) allow to study proton-proton elastic scattering at very low values of squared four-momentum transfer (Mandelstam t), 0:003 <= -t <= 0:035 GeV2=c2. Results of analysis of systematic effects and large statistics of collected data sample reveal possibility of measurement of the Nuclear Slope Parameter with precision not yet achieved at this c.m.s. energy.

  16. A simple technique to increase the linearity and field-of-view in position sensitive photomultiplier tubes

    SciTech Connect

    Clancy, R.L.; Thompson, C.J.; Robar, J.L.; Bergman, A.M.

    1996-12-31

    Crossed anode wire position sensitive photomultiplier tubes (PS-PMTs) detect the location of a light source and provide the X and Y axis coordinates of the event. These coordinates are typically generated using Anger logic, where a resistor chain divides the current flow into two signals for each coordinate (X{sup +}, X{sup -} & Y{sup +}, Y{sup -}). In the standard readout, identical resistor values are used across the entire resistor chain. While this arrangement provides a linear readout in the central portion of the photomultiplier face, the readout is non-linear and sometimes even double valued near the edges of the PS-PMT due to the truncation of the charge beyond the last anode wire. To counter this effect, we have increased the value of the resistance near the ends of each resistor chain in order to compensate for the charge lost beyond the anode wires. Measurements were made using a Hamamatsu R-3941 PS-PMT coupled to a pixellated BGO matrix of cut crystals with a 2mm pitch in each direction. After changing the end resistors, the usable field-of-view increased by 39%. This simple modification should enhance the operation of PS-PMTs in applications such as positron emission mammography, and small animal PET imaging.

  17. 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.

  18. 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.

  19. 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

  20. Theoretical Study of Midwave Infrared HgCdTe nBn Detectors Operating at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Akhavan, Nima Dehdashti; Jolley, Gregory; Umana-Membreno, Gilberto A.; Antoszewski, Jarek; Faraone, Lorenzo

    2015-09-01

    We report a theoretical study of mercury cadmium telluride (HgCdTe) unipolar n-type/barrier/ n-type (nBn) detectors for midwave infrared (MWIR) applications at elevated temperatures. The results obtained indicate that the composition, doping, and thickness of the barrier layer in MWIR HgCdTe nBn detectors can be optimized to yield performance levels comparable with those of ideal HgCdTe p- n photodiodes. It is also shown that introduction of an additional barrier at the back contact layer of the detector structure (nBnn+) leads to substantial suppression of the Auger generation-recombination (GR) mechanism; this results in an order-of-magnitude reduction in the dark current level compared with conventional nBn or p- n junction-based detectors, thus enabling background-limited detector operation above 200 K.

  1. 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.

  2. 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

  3. Study of the Fluorescence Detector Upgrade of the Auger Observatory of Cosmic Rays

    SciTech Connect

    Melo, D. G.; Micheletti, M. I.; Etchegoyen, A.; Rovero, A. C.

    2007-10-26

    The Pierre Auger Observatory (PAO) consists of two kinds of detectors: fluorescence detectors (FD) and surface detectors (SD). In this work we evaluate the effect, on the number and quality of the reconstructed events, of new telescopes (or 'eyes') with an enhanced field of view (FOV) up to approximately 60 degrees in elevation. By using numerical simulations, we calculated the mean total efficiency of the eye, the resolution of reconstruction of the basic parameters that characterize the primary cosmic rays (CR) and the elongation rate. To do this, we considered showers of protons and irons with energies of log(E/eV) between 17.50 and 18.25, impinging inside a circular area, placed in front of the eye at distances varying between 3.5 and 11 km. The extension of the FOV of the eye turns to be very convenient for the selected energy range, due to the fact that the atmospheric depths where the showers develop their maximum number of secondary particles (X{sub max}) are directly observed by the extended eye in most of the cases. Being this X{sub max} a parameter sensible to the chemical composition of the primary cosmic ray, its correct determination is very important in composition studies.

  4. 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.).

  5. POLARIZATION STUDIES OF CdZnTe DETECTORS USING SYNCHROTRON X-RAY RADIATION.

    SciTech Connect

    CAMARDA,G.S.; BOLOTNIKOV, A.E.; CUI, Y.; HOSSAIN, A.; JAMES, R.B.

    2007-07-01

    New results on the effects of small-scale defects on the charge-carrier transport in single-crystal CdZnTe (CZT) material were produced. We conducted detailed studies of the role of Te inclusions in CZT by employing a highly collimated synchrotron x-ray radiation source available at Brookhaven's National Synchrotron Light Source (NSLS). We were able to induce polarization effects by irradiating specific areas with the detector. These measurements allowed the first quantitative comparison between areas that are free of Te inclusions and those with a relatively high concentration of inclusions. The results of these polaration studies will be reported.

  6. 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.

  7. 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.

  8. Commissioning Measurements of ORRUBA Detectors

    NASA Astrophysics Data System (ADS)

    Matthews, C. T.; Cizewski, J. A.; O'Malley, P. D.; Pain, S. D.

    2008-10-01

    The Oak Ridge Rutgers University Barrel Array (ORRUBA) is a silicon detector array being developed by the Center of Excellence for Stewardship Science at Oak Ridge National Laboratory. The array is comprised of two rings of position-sensitive detectors in a cylindrical setup designed to maximize solid angle coverage for (d,p) measurements in inverse kinematics. Each detector has 4 resistive strips, with readout from each strip-end. At forward angles, detector telescopes are used, comprised of a thin non-resistive detector (65μm) for transmission backed by the thicker resistive detector (1000μm) for stopping, allowing particle identification in addition to measurement of the angle and energy of the detected particles. For commissioning, the profile of each detector must be tested to insure that it is functioning properly, and to understand its optimal bias voltage and energy resolution. Measurements of leakage current profiles, full-depletion voltages and energy resolution measurements have been completed. The details of the array, its motivation and these commissioning measurements will be reported.

  9. 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.

  10. 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.

  11. Study of solar activity by measuring cosmic rays with a water Cherenkov detector

    NASA Astrophysics Data System (ADS)

    Bahena Bias, Angélica; Villaseñor, Luis

    2011-04-01

    We report on an indirect study of solar activity by using the Forbush effect which consists on the anti-correlation between the intensity of solar activity and the intensity of secondary cosmic radiation detected at ground level at the Earth. We have used a cylindrical water Cherenkov detector to measure the rate of arrival of secondary cosmic rays in Morelia Mich., Mexico, at 1950 m.a.s.l. We describe the analysis required to unfold the effect of atmospheric pressure and the search for Forbush decreases in our data, the latter correspond to more than one year of continuous data collection.

  12. Study of the Natural Radioactivity Influence on Argo-Ybj Detector

    NASA Astrophysics Data System (ADS)

    Bolognino, I.; Cattaneo, C.; Giroletti, E.; Liguori, G.; Salvini, P.; Vallania, P.; Vigorito, C.

    2011-06-01

    ARGO-YBJ is an extensive air shower detector located at the Yangbajing Cosmic Ray Laboratory (4300 m a.s.l., Tibet, P.R. China). It is made by a single layer of Resistive Plate Chambers organized into 153 units called "clusters" (7.6 × 5.7 m2 of area). The lowest energy threshold of the experiment (about 1 GeV) is obtained in the "scaler operation mode". In this paper the preliminary results of a study on the correlation between Radon concentration in the experimental hall and counting rates are presented.

  13. 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

  14. Studies of the Energy Spectra of Incident Cosmic Radiation by the Networks of Particle Detectors

    NASA Astrophysics Data System (ADS)

    Chilingarian, Ashot A.; Hovsyapayan, Gagik G.

    2007-08-01

    There are numerous indications that particle acceleration took place in supernovae remnants, by pulsars, super-massive black holes, in the galaxy clusters and by stars. As a universal mechanism operated on different scales the stochastic and shock acceleration is pointed. It is very important to use our nearest star - the sun, as laboratory in studying particle acceleration phenomena. The surface particle detectors, along with space-born spectrometers are capable of detecting solar particles in the energy range from KeVs till several Tens of GeV. The large surface arrays are detecting particle in energy range from ~100 TeV till EeV. This richness of information on particle fluxes on different scales can be used in studying physical processes responsible for particle acceleration in Universe. Surface detectors measuring Extensive Air Showers (EAS) initiated by Primary Cosmic Rays (PCR) incident on terrestrial atmosphere have been in operation since the last 50 years with main goal to explore the major enigma of Cosmic Ray (CR) origin and acceleration. Recent achievements of the Atmospheric Cherenkov Telescopes and X-ray space laboratories, establishing the supernova remnants (SNRs) as source of hadronic cosmic rays pose stringent conditions on the quality of the EAS evidence. After establishing the existence of the “knee” in all particle spectrum the most pronounced result from EAS studies is the rigidity dependent shift of the knee position to the highest energies. This feature first observed by the exploiting the separation of the primary beam in different groups of mass in MAKET-ANI, EAS-TOP and KASCADE experiments also pointed to the SNR blast shocks as CR source. The MAKET ANI detector is placed on mountain Aragats (Armenia) on 3200m at sea level (40.50N, 44.20E). More than 1.3 x 10^6 showers with size greater than 10^5 were registered in 1997-2004. The detector has effectively collected the cores of EAS, initiated by primaries with energies of 5 × 10

  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. PMID:17645990

  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. 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.

  18. 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.

  19. 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.

  20. Geoneutrinos and the Sno+ Detector

    NASA Astrophysics Data System (ADS)

    Tolich, N.

    2014-12-01

    When the SNO+ detector begins operation within two years, it will be a sensitive geo-neutrino detector. The detectors location in Sudbury, Canada, will allow us to study the geo-neutrino signal originating from the surrounding continental crust. Combining future results from the SNO+ detector with those from the KamLAND and Borexino geo-neutrino detectors, respectively in Japan and Italy, will allow us to study the variation in the geo-neutrino signal for detectors located in very different crust types. I will talk about the status of the SNO+ detector along with the potential geo-neutrino results from such a detector.

  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. Study of gamma-ray detector performance of Cd1-xZnxTe crystal treated by different etchants

    NASA Astrophysics Data System (ADS)

    Chen, Henry; Egarievwe, Stephen U.; Hu, Z.; Tong, J.; Shi, Detang T.; Wu, G. H.; Chen, Kuo-Tong; George, M. A.; Collins, W. E.; Burger, Arnold; James, Ralph B.; Stahle, Carl M.; Bartlett, Lyle M.

    1996-07-01

    Radiation detectors have been fabricated from Cd1-xZnxTe crystals and their performance has been studied with respect their Cd1-xZnxTe surface preparation. Energy resolution, leakage current, resistivity, ohmicity as well as surface roughness of the detectors were measured and compared for various chemical treatments. Etching in lactic acid has been found to lead to better ohmic contract, a rougher surface and higher leakage current. Bromine is effective in removing the damaged layer and when added to 20 percent lactic acid in ethylene glycol leads to a lower leakage current and consequently a better energy resolution. The best detector performance was obtained with a two step treatment consisting of a standard etchant (5 percent Br in methanol) followed by 2 percent Br in'20 percent lactic acid in ethylene glycol'. The results clearly demonstrate the important of surface chemical treatments in the fabrication of Cd1-xZnxTe radiation detectors.

  3. Compton imager based on a single planar segmented HPGe detector

    NASA Astrophysics Data System (ADS)

    Khaplanov, A.; Pettersson, J.; Cederwall, B.

    2007-10-01

    A collimator-free Compton imaging system has been developed based on a single high-purity germanium detector and used to generate images of radioactive sources emitting γ rays. The detector has a planar crystal with one pixellated contact with a total of 25 segments. Pulse shape analysis has been applied to achieve a 3D-position sensitivity of the detector. The first imaging results from this detector are presented, based on the reconstruction of events where a γ ray is fully absorbed after scattering between adjacent segments.

  4. 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.

  5. 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.

  6. 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".

  7. 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

  8. Study of a high-resolution PET system using a silicon detector probe.

    PubMed

    Brzeziński, K; Oliver, J F; Gillam, J; Rafecas, M

    2014-10-21

    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 mm(3) 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

  9. 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

  10. A new thermal neutron detector for protein crystallography

    SciTech Connect

    Mahler, G.J.; Radeka, V.; Schaknowski, N.A.; Smith, G.C.; Yu, B.; Zojceski, Z.

    1999-12-01

    A new position-sensitive detector is being developed for protein crystallography studies at a spallation source. Based on eight, independent, wire proportional chamber segments housed in a curved pressure vessel, the device covers a scattering angle of 120 degrees, and has a collecting area of 1.5m by 20cm. The position resolution will be about 1.3 mm FWHM, with a total counting rate in excess of one million per second. Timing resolution, essential for a spallation source application, is of order 1{micro}s and provides neutron energy determination that is well suited for crystallography. Advanced features of this device include a digital centroid finding scheme, a seamless readout between segments, and a wire array design that minimizes anode modulation. Details of the mechanical design are given, together with digital centroid measurements that illustrate accurate, uniform response.

  11. 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.

  12. An electrochemical detector array to study cell biology on the nanoscale

    NASA Astrophysics Data System (ADS)

    Dias, Andrew F.; Dernick, Gregor; Valero, Vicente; Yong, Ming G.; James, Conrad D.; Craighead, Harold G.; Lindau, Manfred

    2002-06-01

    Nanobiotechnology is a field that utilizes the techniques of nano- and microfabrication to study biosystems or to use biological material and principles to build new devices. As an example we discuss the development of a nanofabricated electrochemical detector array that reveals the spatio-temporal dynamics of exocytosis in single chromaffin cells. In a quantal release event a single vesicle fuses with the plasma membrane releasing its contents through the fusion pore. The time-resolved amperometric currents measured by the individual electrodes detecting different fractions of the released molecules allow determination of the time course as well as localization of quantal events. Such a device may be applicable to study the correlation of exocytotic events with signalling events that could be simultaneously monitored by fluorescence microscopy.

  13. Microsphere plate detectors used with a compact Mott polarimeter for time-of-flight studies

    SciTech Connect

    Snell, G.; Viefhaus, J.; Dunning, F. B.; Berrah, N.

    2000-06-01

    A compact retarding-potential Mott polarimeter combined with microsphere plates (MSP) as electron detectors was built to perform spin-resolved time-of-flight electron spectroscopy. The comparison of the performance of MSP and channeltron detectors shows that the MSP detector has a better time resolution but a lower efficiency. The overall time resolution of the system was determined to be 350 ps using synchrotron radiation pulses. (c) 2000 American Institute of Physics.

  14. 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.

  15. 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.

  16. Evaluation of New Contact Technology for A Planar High-Purity Germanium Double-Sided Strip Detector

    NASA Astrophysics Data System (ADS)

    Jackson, E.; Chowdhury, P.; Lister, C. J.; Diaz, C.; Skinner, M.; Hull, E.; Pehl, R.

    2013-10-01

    New technologies for making position sensitive γ-ray detectors have applications in space science, medical imaging, homeland security, and nuclear structure research. One promising approach uses high-purity germanium wafers in Low Energy Photon Spectrometer (LEPS) geometry, where segmentation of the electrodes into strips forms a Double-Sided Strip Detector (DSSD). The position-sensitivity afforded by the many strips is ideal for the study of Compton scattering and polarization. However, challenges with the manufacture and performance of the rectifying contacts continue to plague the advancement of planar DSSDs. The data gathered from the combination of multiple strips' signals suffers from cross-talk between the strips and charge loss due to wide inter-strip gaps. A planar, high-purity DSSD has been developed by PHDs Co. with an alternative electrode material, amorphous germanium, that can be placed such that the gaps between the strips are half the width required by other contact material. This research seeks to quantify the performance gains of the amorphous germanium contacts and smaller inter-strip gaps while exploring the possibilities for this DSSD as an imager and polarization detector. Research supported by the U.S. Department of Energy (DE-FG02-94ER40848).

  17. A study of nonflammable gas mixtures for limited streamer tubes in the VENUS detector at TRISTAN

    NASA Astrophysics Data System (ADS)

    Uebayashi, T.; Haba, J.; Kamitani, T.; Kanematsu, N.; Nagashima, Y.; Osabe, H.; Sakamoto, S.; Sugimoto, S.; Suzuki, Y.; Tsukamoto, A.; Yamashita, Y.; Sumiyoshi, T.; Takasaki, F.; Homma, Y.; Hojyo, Y.; Sakae, H.

    1988-03-01

    Performances of limited streamer tubes operated with nonflammable gas mixtures composed of argon (Ar), carbon-dioxide (CO2) and isobutane (i-C4H10) with ratios of 1:1.5:0.15, 1:2:0.2, 1:3:0.3, 1:4:0.4 and 1:6:0.6 were studied. It was found that these mixtures were very suitable for the VENUS detector. The charge spectra exhibited very sharp distributions and indicated the possibility for the limited streamer tubes to be applied to calorimetry use. A mixture of 1:2:0.2 was chosen for the VENUS streamer tubes because of its moderate gain and long efficiency plateau.

  18. A study of nonflammable gas mixtures for limited streamer tubes in the VENUS detector at TRISTAN

    NASA Astrophysics Data System (ADS)

    Uebayashi, T.; Haba, J.; Kamitani, T.; Kanematsu, N.; Nagashima, Y.; Osabe, H.; Sakamoto, S.; Sugimoto, S.; Suzuki, Y.; Tsukamoto, A.; Yamashita, Y.; Sumiyoshi, T.; Takasaki, F.; Homma, Y.; Hojyo, Y.; Sakae, H.

    1998-03-01

    Performances of limited streamer tubes operated with nonflammable gas mixtures composed of argon (Ar), carbon-dioxide (CO2) and isobutane (i-C4H10) with ratios of 1:1.5:0.15, 1:2:0.2, 1:3:0.3, 1:4:0.4 and 1:6:0.6 were studied. It was found that these mixtures were very suitable for the VENUS detector. The charge spectra exhibited very sharp distributions and indicated the possibility for the limited streamer tubes to be applied to calorimetry use. A mixture of 1:2:0.2 was chosen for the VENUS streamer tubes because of its moderate gain and long efficiency plateau.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  1. Study of the Dalitz decay ϕ → ηe+e- with the KLOE detector

    NASA Astrophysics Data System (ADS)

    Babusci, D.; Balwierz-Pytko, I.; Bencivenni, G.; Bloise, C.; Bossi, F.; Branchini, P.; Budano, A.; Caldeira Balkeståhl, L.; Ceradini, F.; Ciambrone, P.; Curciarello, F.; Czerwiński, E.; Danè, E.; De Leo, V.; De Lucia, E.; De Robertis, G.; De Santis, A.; De Simone, P.; Di Cicco, A.; Di Domenico, A.; Di Salvo, R.; Domenici, D.; Erriquez, O.; Fanizzi, G.; Fantini, A.; Felici, G.; Fiore, S.; Franzini, P.; Gajos, A.; Gauzzi, P.; Giardina, G.; Giovannella, S.; Graziani, E.; Happacher, F.; Heijkenskjöld, L.; Höistad, B.; Johansson, T.; Kamińska, D.; Krzemien, W.; Kupsc, A.; Lee-Franzini, J.; Loddo, F.; Loffredo, S.; Mandaglio, G.; Martemianov, M.; Martini, M.; Mascolo, M.; Messi, R.; Miscetti, S.; Morello, G.; Moricciani, D.; Moskal, P.; Palladino, A.; Passeri, A.; Patera, V.; Prado Longhi, I.; Ranieri, A.; Santangelo, P.; Sarra, I.; Schioppa, M.; Sciascia, B.; Silarski, M.; Tortora, L.; Venanzoni, G.; Wiślicki, W.; Wolke, M.

    2015-03-01

    We have studied the vector to pseudoscalar conversion decay ϕ → ηe+e-, with η →π0π0π0, with the KLOE detector at DAΦNE. The data set of 1.7 fb-1 of e+e- collisions at √{ s} ∼Mϕ contains a clear conversion decay signal of ∼ 31 , 000 events from which we measured a value of BR (ϕ → ηe+e-) = (1.075 ± 0.007 ± 0.038) ×10-4. The same sample is used to determine the transition form factor by a fit to the e+e- invariant mass spectrum, obtaining bϕη = (1.28 ±0.10-0.08+0.09) GeV-2, that improves by a factor of five the precision of the previous measurement and is in good agreement with VMD expectations.

  2. 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)

  3. 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.

  4. Transmutation detectors

    NASA Astrophysics Data System (ADS)

    Viererbl, L.; Lahodová, Z.; Klupák, V.; Sus, F.; Kučera, J.; Kůs, P.; Marek, M.

    2011-03-01

    We have designed a new type of detectors, called transmutation detectors, which can be used primarily for neutron fluence measurement. The transmutation detector method differs from the commonly used activation detector method in evaluation of detector response after irradiation. Instead of radionuclide activity measurement using radiometric methods, the concentration of stable non-gaseous nuclides generated by transmutation in the detector is measured using analytical methods like mass spectrometry. Prospective elements and nuclear reactions for transmutation detectors are listed and initial experimental results are given. The transmutation detector method could be used primarily for long-term measurement of neutron fluence in fission nuclear reactors, but in principle it could be used for any type of radiation that can cause transmutation of nuclides in detectors. This method could also be used for measurement in accelerators or fusion reactors.

  5. 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)

  6. Silicon photomultiplier based photon detector module as a detector of Cherenkov photons

    NASA Astrophysics Data System (ADS)

    Korpar, Samo; Chagani, Hassan; Dolenec, Rok; Križan, Peter; Pestotnik, Rok; Stanovnik, Aleš

    2010-11-01

    We have constructed and tested a module, consisting of 64 (= 8×8) Hamamatsu MPPC S10362-11-100P silicon photomultipliers, for position sensitive detection of Cherenkov photons. Suitable light concentrators were produced to increase the efficiency and to improve the signal to noise ratio. The results of our measurements indicate that the performance of such a Cherenkov counter with aerogel radiator could meet the requirements of particle identification at the foreseen upgraded Belle detector.

  7. Fast-neutron spectroscopy studies using induced-proton tracks in PADC track detectors

    NASA Astrophysics Data System (ADS)

    El-Sersy, A. R.; Eman, S. A.

    2010-06-01

    In this work, a simple and adequate method for fast-neutron spectroscopy is proposed. This method was performed by free-in-air fast-neutron irradiation of CR-39 Nuclear Track Detectors (NTD) using an Am-Be source. Detectors were then chemically etched to remove few layers up to a thickness of 6.25 μm. By using an automatic image analyzer system for studying the registration of the induced-proton tracks in the NTD, the obtained data were analyzed via two tracks shapes. In the first one, the elliptical tracks were eliminated from the calculation and only the circular ones were considered in developing the response function. In the second method all registered tracks were considered and the corresponding response function was obtained. The rate of energy loss of the protons as a function of V[(d E/d X) - V] was calculated using the Monte Carlo simulation. The induced-proton energy was extracted from the corresponding d E/d X in NTD using a computer program based on the Bethe-Bloch function. The energy of the incident particles was up to few hundred MeV/nucleon. The energy of the interacting neutrons was then estimated by means of the extracted induced-proton energies and the scattering angle. It was found that the present resulting energy distribution of the fast-neutron spectrum from the Am-Be source was similar to that given in the literature where an average neutron energy of 4.6MeV was obtained.

  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. 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.

  10. Studies of the Sudbury Neutrino Observatory detector and sonoluminescence using a sonoluminescent source

    NASA Astrophysics Data System (ADS)

    McDonald, Douglas Steven

    The Sudbury Neutrino Observatory (SNO) is the first heavy water Cerenkov solar neutrino detector. 1000 metric tonnes of heavy water is used as a neutrino target and detection medium. SNO is designed to measure the flux and energy spectrum of high energy solar electron neutrinos via charged current interactions of electron neutrinos with deuterons in the heavy water. SNO can also measure the total high energy solar neutrino flux of neutrinos of all flavors via neutral current interactions with deuterons. The physics of solar models and solar neutrinos is presented. The physics of SNO and the SNO detector are described in detail. Two sonoluminescence sources were developed for use in calibrations of the SNO detector. The sonoluminescence source outperformed the standard SNO optical source, a nitrogen laser with a diffuser ball, by 25% in measurements of photomultiplier tube timing accuracy. Two systematic effects with the SNO electronics were discovered. Electronic crosstalk between channels has been measured for charges greater than 5 photoelectrons. An efficient cut has been developed to minimize this systematic error with an upper limit on signal loss of 0.4% times the PMT occupancy. Electronics crosstalk will affect solar neutrino analyses as it falsely adds PMT hits to some fraction of the events. A small anticorrelation of photomultiplier charges for electronics channels in close proximity has been measured. It has been shown that this subtle effect does not affect the number of photons detected, only the photomultiplier charges. A SL source and the SNO detector were used to study three properties of sonoluminescence. An analysis of SL data with regard to back-to-back photon correlations is presented. The results are consistent with no back-to- back photon correlations with an upper limit on the strength of back-to-back photon correlations of 3.16% for unfiltered SL light, and 0.5% for filtered SL light (λ = 420 nm) at the 95% confidence level. The SL photon

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. Beam test studies of 3D pixel sensors irradiated non-uniformly for the ATLAS forward physics detector

    NASA Astrophysics Data System (ADS)

    Grinstein, S.; Baselga, M.; Boscardin, M.; Christophersen, M.; Da Via, C.; Dalla Betta, G.-F.; Darbo, G.; Fadeyev, V.; Fleta, C.; Gemme, C.; Grenier, P.; Jimenez, A.; Lopez, I.; Micelli, A.; Nelist, C.; Parker, S.; Pellegrini, G.; Phlips, B.; Pohl, D.-L.; Sadrozinski, H. F.-W.; Sicho, P.; Tsiskaridze, S.

    2013-12-01

    Pixel detectors with cylindrical electrodes that penetrate the silicon substrate (so called 3D detectors) offer advantages over standard planar sensors in terms of radiation hardness, since the electrode distance is decoupled from the bulk thickness. In recent years significant progress has been made in the development of 3D sensors, which culminated in the sensor production for the ATLAS Insertable B-Layer (IBL) upgrade carried out at CNM (Barcelona, Spain) and FBK (Trento, Italy). Based on this success, the ATLAS Forward Physics (AFP) experiment has selected the 3D pixel sensor technology for the tracking detector. The AFP project presents a new challenge due to the need for a reduced dead area with respect to IBL, and the in-homogeneous nature of the radiation dose distribution in the sensor. Electrical characterization of the first AFP prototypes and beam test studies of 3D pixel devices irradiated non-uniformly are presented in this paper.

  16. Jet-underlying event studies with ALICE detector at the LHC

    NASA Astrophysics Data System (ADS)

    Abelev, Betty

    2011-10-01

    Relativistic heavy ion collisions produce a state of strongly interacting matter of quarks and gluons, called the Quark Gluon Plasma (QGP). Measuring particle production via fragmentation (specifically in jets) and understanding parton energy loss in the QGP enables one to directly probe the medium. One of the necessary components in studying jets in heavy ion events is the ability to isolate jets from the soft physics background, i.e., the underlying event. Thus it is important to understand the underlying event properties, in particular, energy fluctuations. This presentation will address the initial studies done to map out the underlying event in √{ s} = 7 TeV pp collisions measured with the ALICE detector at the LHC, as preparation for extending these studies to Pb-Pb collisions. The focus will be on the analyses performed with the ALICE Electro-Magnetic Calorimeter (EMCal). EMCal is especially well-suited for the measurement of high-momentum particles which are produced predominantly in jets and therefore is a useful tool in subtracting the jet cone from the underlying event. For the ALICE Collaboration.

  17. Study of neutrino interactions at the T2K near detector

    NASA Astrophysics Data System (ADS)

    Hillairet, A.; T2K Collaboration

    2013-10-01

    The Tokai-To-Kamioka (T2K) experiment was designed to measure the oscillation of muon neutrinos produced at the J-PARC accelerator in Japan. The Super-Kamiokande detector acts as the far detector and a near detector is installed in the path of the neutrino beam to reduce uncertainties on the flux and cross sections. This near detector, called ND280, is located 280 m from the production target of the T2K neutrino beamline in order to measure the characteristics of the beam prior to any oscillation. The first ND280 analysis of the momentum-angle distribution of the muon produced by muon neutrino charged current interactions has been performed. These results have also been used to determine a flux-averaged cross section.

  18. A preliminary study on the use of cadmium telluride detectors in the scintigraphy of thyroid gland

    NASA Astrophysics Data System (ADS)

    Mancini, A. M.; Quirini, A.; Vasanelli, L.; Bacci, C.; Bernabei, R.; Pani, R.; Rispoli, B.; Ballesio, P. L.; Furetta, C.

    1981-10-01

    A cadmium telluride gamma detector has been used for monitoring the activity of a radioactive tracer in a thyroid gland. Preliminary measurements are reported in comparison with those obtained with a standard NaI(Tl) scintillator.

  19. A focal plane detector design for a wide-band Laue-lens telescope

    NASA Astrophysics Data System (ADS)

    Caroli, Ezio; Auricchio, Natalia; Amati, Lorenzo; Bezsmolnyy, Yuriy; Budtz-Jørgensen, Carl; da Silva, Rui M. Curado; Frontera, Filippo; Pisa, Alessandro; del Sordo, Stefano; Stephen, John B.; Ventura, Giulio

    2005-12-01

    The energy range above 60 keV is important for the study of many open problems in high energy astrophysics such as the role of Inverse Compton with respect to synchrotron or thermal processes in GRBs, non thermal mechanisms in SNR, the study of the high energy cut-offs in AGN spectra, and the detection of nuclear and annihilation lines. Recently the development of high energy Laue lenses with broad energy bandpasses from 60 to 600keV have been proposed for a Hard X ray focusing Telescope (HAXTEL) in order to study the X-ray continuum of celestial sources. The required focal plane detector should have high detection efficiency over the entire operative range, a spatial resolution of about 1mm, an energy resolution of a few keV at 500keV and a sensitivity to linear polarization. We describe a possible configuration of the focal plane detector based on several CdTe/CZT pixelated layers stacked together to achieve the required detection efficiency at high energy. Each layer can operate both as a separate position sensitive detector and polarimeter or work with other layers to increase the overall photopeak efficiency. Each layer has a hexagonal shape in order to minimize the detector surface required to cover the lens field of view. The pixels would have the same geometry so as to provide the best coupling with the lens point spread function and to increase the symmetry for polarimetric studies.

  20. DETECTORS AND EXPERIMENTAL METHODS: Monte Carlo study on the low momentum μ-π identification of the BESIII EM calorimeter

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Gang; Lü, Jun-Guang; He, Kang-Lin; An, Zheng-Hua; Cai, Xiao; Dong, Ming-Yi; Fang, Jian; Hu, Tao; Liu, Wan-Jin; Lu, Qi-Wen; Ning, Fei-Peng; Sun, Li-Jun; Sun, Xi-Lei; Wang, Xiao-Dong; Xue, Zhen; Yu, Bo-Xiang; Zhang, Ai-Wu; Zhou, Li

    2009-10-01

    The BESIII detector has a high-resolution electromagnetic calorimeter which can be used for low momentum μ-π identification. Based on Monte Carlo simulations, μ-π separation was studied. A multilayer perceptron neural network making use of the defined variables was used to do the identification and a good μ-π separation result was obtained.

  1. High efficiency neutron sensitive amorphous silicon pixel detectors

    SciTech Connect

    Mireshghi, A.; Cho, G.; Drewery, J.S.; Hong, W.S.; Jing, T.; Lee, H.; Kaplan, S.N.; Perez-Mendez, V.

    1993-11-01

    A multi-layer a-Si:H based thermal neutron detector was designed, fabricated and simulated by Monte Carlo method. The detector consists of two PECVD deposited a-Si:H pin detectors interfaced with coated layers of Gd, as a thermal neutron converter. Simulation results indicate that a detector consisting of 2 Gd films with thicknesses of 2 and 4 {mu}m, sandwiched properly with two layers of sufficiently thick ({approximately}30{mu}m) amorphous silicon diodes, has the optimum parameters. The detectors have an intrinsic efficiency of about 42% at a threshold setting of 7000 electrons, with an expected average signal size of {approximately}12000 electrons which is well above the noise. This efficiency will be further increased to nearly 63%, if we use Gd with 50% enrichment in {sup 157}Gd. We can fabricate position sensitive detectors with spatial resolution of 300 {mu}m with gamma sensitivity of {approximately}1 {times} 10{sup {minus}5}. These detectors are highly radiation resistant and are good candidates for use in various application, where high efficiency, high resolution, gamma insensitive position sensitive neutron detectors are needed.

  2. Response regime studies on standard detectors for decay time determination in phosphor thermometry

    NASA Astrophysics Data System (ADS)

    Knappe, C.; Abou Nada, F.; Lindén, J.; Richter, M.; Aldén, M.

    2013-09-01

    This work compares the extent of linear response regimes from standard time-resolving optical detectors for phosphor thermometry. Different types of Photomultipliers (ordinary and time-gated) as well as an Avalanche Photodiode are tested and compared using the phosphorescent time decay of CdWO4 that ranges from 10 μs down to a few ns within a temperature span of 290 to 580 K. Effects originating from incipient detector saturation, far from obvious to the operator's eye, are revealed as a change in evaluated phosphorescence decay time. Since the decay time of thermographic phosphors itself is used for temperature determination - systematic temperature errors up to several tens of Kelvins may be introduced by such detector saturation. A detector mapping procedure is suggested in order to identify linear response regions where the decay-to-temperature evaluation can be performed unbiased. Generation of such a library is highly recommended prior to any quantitative measurement attempt. Using this detector library, even signals collected in the partly saturated regime can be corrected to their unbiased value extending the usable detector operating range significantly. Further, the use of an external current-to-voltage amplifier proved useful for most applications in time-based phosphor thermometry helping to limit saturation effects whilst maintaining a reasonable bandwidth and signal outputs.

  3. Improving the spatial resolution in CZT detectors using charge sharing effect and transient signal analysis: Simulation study

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaoqing; Cheng, Zeng; Deen, M. Jamal; Peng, Hao

    2016-02-01

    Cadmium Zinc Telluride (CZT) semiconductor detectors are capable of providing superior energy resolution and three-dimensional position information of gamma ray interactions in a large variety of fields, including nuclear physics, gamma-ray imaging and nuclear medicine. Some dedicated Positron Emission Tomography (PET) systems, for example, for breast cancer detection, require higher contrast recovery and more accurate event location compared with a whole-body PET system. The spatial resolution is currently limited by electrode pitch in CZT detectors. A straightforward approach to increase the spatial resolution is by decreasing the detector electrode pitch, but this leads to higher fabrication cost and a larger number of readout channels. In addition, inter-electrode charge spreading can negate any improvement in spatial resolution. In this work, we studied the feasibility of achieving sub-pitch spatial resolution in CZT detectors using two methods: charge sharing effect and transient signal analysis. We noted that their valid ranges of usage were complementary. The dependences of their corresponding valid ranges on electrode design, depth-of-interaction (DOI), voltage bias and signal triggering threshold were investigated. The implementation of these two methods in both pixelated and cross-strip configuration of CZT detectors were discussed. Our results show that the valid range of charge sharing effect increases as a function of DOI, but decreases with increasing gap width and bias voltage. For a CZT detector of 5 mm thickness, 100 μm gap and biased at 400 V, the valid range of charge sharing effect was found to be about 112.3 μm around the gap center. This result complements the valid range of the transient signal analysis within one electrode pitch. For a signal-to-noise ratio (SNR) of ~17 and preliminary measurements, the sub-pitch spatial resolution is expected to be ~30 μm and ~250 μm for the charge sharing and transient signal analysis methods

  4. Peak shifted properties of the "low background NaI(Tl) detectors": An experimental study of response function behavior in different temperature and acquisition time

    NASA Astrophysics Data System (ADS)

    Rezaei Moghaddam, Y.; Rafat Motavalli, L.; Miri Hakimabadi, H.

    2016-09-01

    Due to the necessity of using low background NaI detector in sensitive and accurate measurements, study on the response function variations in different conditions is very important. These types of detectors have different responses in various measurement conditions, including time, temperature and high voltage. In this study, the response function of 76 B 76 LB NaI (SCIONIX) in different conditions is discussed. According to the channel shifting in these detectors and its direct effect on degrading the resolution, the most convenient measurement condition for these detectors, is proposed. Finally, it is recommended that before long-time measurements a "waiting time" is needed to avoid the channel shifting effects.

  5. Electron Echo 6 - a Study by Particle Detectors of Electrons Artificially Injected Into the Magnetosphere.

    NASA Astrophysics Data System (ADS)

    Malcolm, Perry Robert

    The ECHO-6 sounding rocket was launched from the Poker Flat Research Range, Alaska on 30 March 1983. A Terrier-Black Brant launch vehicle carried the payload on a northward trajectory over an auroral arc and to an apogee of 216 kilometers. The primary objective of the ECHO-6 experiment was to evaluate electric fields, magnetic fields, and plasma processes in the distant magnetosphere by injecting electron beams in the ionosphere and observing conjugate echoes. The experiment succeeded in injecting 10-36 KeV beams during the existence of a moderate growth phase aurora, an easterly electrojet system, and a pre -midnight inflation condition of the magnetosphere. The ECHO-6 payload system consisted of an accelerator MAIN payload, a free-flying Plasma Diagnostics Package (PDP), and four rocket propelled Throw Away Detectors (TADs). The PDP was ejected from the MAIN payload to analyze electric fields, plasma particles, energetic electrons, and photometric effects produced by beam injections. The TADs were ejected from the MAIN payload in a pattern to detect echoes in the conjugate echo region south of the beam emitting MAIN payload. The TADs reached distances exceeding 3 kilometers from the MAIN payload and made measurements of the ambient electrons by means of solid state detectors and electrostatic analyzers. In spite of the perfect operation of the TAD system and a rigorous analysis of the particle data, no conjugate echoes have been identified. Through the use of a new dynamic magnetic field model (Olson and Pfitzer, 1982) and satellite magnetometer measurements, it has been determined that the echoing electrons returned out of range of the TADs as a result of their bounce times and curvature-gradient drifts being increased beyond the expected limits for an inflated magnetic field. This dynamic model was then applied to the study of echoes seen during the ECHO-4 flight resulting in a significant increase in the calculated energy of the echo electrons and better

  6. Accuracy of the geometric-mean method for determining spatial resolutions of tracking detectors in the presence of multiple Coulomb scattering

    NASA Astrophysics Data System (ADS)

    Zhang, A.; Hohlmann, M.

    2016-06-01

    The geometric-mean method is often used to estimate the spatial resolution of a position-sensitive detector probed by tracks. It calculates the resolution solely from measured track data without using a detailed tracking simulation and without considering multiple Coulomb scattering effects. Two separate linear track fits are performed on the same data, one excluding and the other including the hit from the probed detector. The geometric mean of the widths of the corresponding exclusive and inclusive residual distributions for the probed detector is then taken as a measure of the intrinsic spatial resolution of the probed detector: σ=√σex·σin. The validity of this method is examined for a range of resolutions with a stand-alone Geant4 Monte Carlo simulation that specifically takes multiple Coulomb scattering in the tracking detector materials into account. Using simulated as well as actual tracking data from a representative beam test scenario, we find that the geometric-mean method gives systematically inaccurate spatial resolution results. Good resolutions are estimated as poor and vice versa. The more the resolutions of reference detectors and probed detector differ, the larger the systematic bias. An attempt to correct this inaccuracy by statistically subtracting multiple-scattering effects from geometric-mean results leads to resolutions that are typically too optimistic by 10-50%. This supports an earlier critique of this method based on simulation studies that did not take multiple scattering into account.

  7. Design Considerations for a Large Metal-Loaded Liquid Scintillator Detector with Applications for Solar Neutrino and Double Beta Decay Studies

    NASA Astrophysics Data System (ADS)

    Doe, Peter; Robertson, Hamish; Gehman, Victor; Gehring, George; Iwamoto, Hideko; Will, Doug

    2002-10-01

    The realization of a large, metal-loaded liquid scintillator detector has exciting possibilities in the areas of Double Beta Decay, low-energy solar neutrino, and supernova neutrino studies. We have used statistical considerations to arrive at an analytical expression which will allow us to optimize a detector design for energy and spatial resolution. Using these results, we consider the possible use of Avalanche Photo-Diode detectors operated in the Geiger regime as a possible replacement for Photomultiplier Tubes.

  8. Quality studies of the data taking conditions for the Auger fluorescence detector

    SciTech Connect

    Caruso, R.; Fonte, R.; Insolia, A.; Petrera, S.; Rodriquez Martino, J.; /Rome U.,Tor Vergata

    2005-07-01

    As more than half of the Fluorescence Detector (FD) of the Auger Observatory is completed, data taking is becoming a routine job. It is then necessary to follow strict procedures to assure the quality of the data. An overview of the data taking methods is given. The nature of the FD background signal is due to the night sky brightness (stars and planet faint light, moonlight, twilight, airglow, zodiacal and artificial light) and to the electronic background (photomultiplier and electronic noise). The analysis of the fluctuations in the FADC signal (variance analysis), directly proportional to the background mean light level, performed for each night of data taking is used to monitor the FD background signal. The data quality is analyzed using different techniques, described in detail. Examples of trigger rates, number of stereo events, dead time due to moonlight, weather or hardware problems are given. The analysis comprises several months of data taking, giving an overview of the FD capabilities, performance and allowing a systematic study of data and their correlation with the environment.

  9. Study of surface recombination on cleaved and passivated edges of Si detectors

    NASA Astrophysics Data System (ADS)

    Gaubas, E.; Ceponis, T.; Vaitkus, J. V.; Fadeyev, V.; Ely, S.; Galloway, Z.; F-W Sadrozinski, H.; Christophersen, M.; Phlips, B. F.; Gorelov, I.; Hoeferkamp, M.; Metcalfe, J.; Seidel, S.

    2016-03-01

    The effectiveness of the passivation of a cleaved boundary of large area strip detectors has been studied by using Al2O3 formed by atomic layer deposition technology for p-Si structures and Si x N y grown on n-Si by plasma enhanced chemical vapour deposition. The parameters of bulk and surface recombinations have been examined in a contactless mode implemented through analysis of the microwave-probed photoconductivity transients. Rather efficient and reproducible passivation, revealed through the reduction of surface recombination velocities from ˜2 × 104 to 5 × 103 cm s-1 for n-Si and from ˜2 × 104 to 3 × 102 cm s-1 for p-Si samples, has been obtained. The existence of trapping centres together with recombination defects has been revealed at the cleaved interface within the passivating layer. It has been revealed that the impact of surface recombination is negligible when bulk radiation defects are dominant in samples irradiated with fluences >1014 neq cm-2.

  10. Fragmentation studies with the CHIMERA detector at LNS in Catania: recent progress

    NASA Astrophysics Data System (ADS)

    Pagano, A.; Alderighi, M.; Amorini, F.; Anzalone, A.; Arena, L.; Auditore, L.; Baran, V.; Bartolucci, M.; Berceanu, I.; Blicharska, J.; Brzychczyk, J.; Bonasera, A.; Borderie, B.; Bougault, R.; Bruno, M.; Cardella, G.; Cavallaro, S.; Chatterjee, M. B.; Chbihi, A.; Cibor, J.; Colonna, M.; D'Agostino, M.; Dayras, R.; De Filippo, E.; Di Toro, M.; Gawlikowicz, W.; Geraci, E.; Giustolisi, F.; Grzeszczuk, A.; Guazzoni, P.; Guinet, D.; Iacono-Manno, M.; Kowalski, S.; La Guidara, E.; Lanzano, G.; Lanzalone, G.; Le Neindre, N.; Li, S.; Lo Nigro, S.; Maiolino, C.; Majka, Z.; Manfredi, G.; Paduszynski, T.; Papa, M.; Petrovici, M.; Piasecki, E.; Pirrone, S.; Planeta, R.; Politi, G.; Pop, A.; Porto, F.; Rivet, M. F.; Rosato, E.; Rizzo, F.; Russo, S.; Russotto, P.; Sassi, M.; Sechi, G.; Simion, V.; Siwek-Wilczynska, K.; Skwira, I.; Sperduto, M. L.; Steckmeyer, J. C.; Swiderski, L.; Trifiro`, A.; Trimarchi, M.; Vannini, G.; Vigilante, M.; Wieleczko, J. P.; Wilczynski, J.; Wu, H.; Xiao, Z.; Zetta, L.; Zipper, W.

    2004-04-01

    The new detector CHIMERA, in its final 4π configuration, has been installed at Laboratori Nazionali del Sud (LNS) in Catania in January 2003. Beams of different energies ranging from protons to Au ions were delivered by the Tandem and the Super Conducting Cyclotron for nuclear reaction studies, in agreement with the approval of the Scientific Advisory Committee of LNS. Recent experimental results confirm very low energy thresholds of the trigger (below 0.5 MeV/nucleon), ensured within a wide dynamical range. Good characteristics of identification of light charged particles and heavy fragments have been obtained by using three detection techniques: Δ E-E, Δ E-time of flight, and the Pulse-Shape discrimination method. We present results of recent analysis concerning the production of intermediate mass fragments (IMF) in semi-peripheral collisions. Our results combined with theoretical Boltzmann-Nordheim-Vlasov simulations clearly demonstrate the presence of very fast processes of IMF production in the overlapping region of the target and projectile nuclei during re-separation, i.e. in the time scale comparable with the collision time. Evidence for slower, sequential-like production of IMF's is also shown.

  11. Study the radiation damage effects in Si microstrip detectors for future HEP experiments

    NASA Astrophysics Data System (ADS)

    Lalwani, Kavita; Jain, Geetika; Dalal, Ranjeet; Ranjan, Kirti; Bhardwaj, Ashutosh

    2016-07-01

    Silicon (Si) detectors are playing a key role in High Energy Physics (HEP) experiments due to their superior tracking capabilities. In future HEP experiments, like upgrade of the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), CERN, the silicon tracking detectors will be operated in a very intense radiation environment. This leads to both surface and bulk damage in Si detectors, which in turn will affect the operating performance of Si detectors. It is important to complement the measurements of the irradiated Si strip detectors with device simulation, which helps in understanding of both the device behavior and optimizing the design parameters needed for the future Si tracking system. An important ingredient of the device simulation is to develop a radiation damage model incorporating both bulk and surface damage. In this work, a simplified two-trap model is incorporated in device simulation to describe the type-inversion. Further, an extensive simulation of effective doping density as well as electric field profile is carried out at different temperatures for various fluences.

  12. Studies for a 10 μs, thin, high resolution CMOS pixel sensor for future vertex detectors

    NASA Astrophysics Data System (ADS)

    Voutsinas, G.; Amar-Youcef, S.; Baudot, J.; Bertolone, G.; Brogna, A.; Chon-Sen, N.; Claus, G.; Colledani, C.; Dorokhov, A.; Dozière, G.; Dulinski, W.; Degerli, Y.; De Masi, R.; Deveaux, M.; Gelin, M.; Goffe, M.; Hu-Guo, Ch.; Himmi, A.; Jaaskelainen, K.; Koziel, M.; Morel, F.; Müntz, C.; Orsini, F.; Santos, C.; Schrader, C.; Specht, M.; Stroth, J.; Valin, I.; Wagner, F. M.; Winter, M.

    2011-06-01

    Future high energy physics (HEP) experiments require detectors with unprecedented performances for track and vertex reconstruction. These requirements call for high precision sensors, with low material budget and short integration time. The development of CMOS sensors for HEP applications was initiated at IPHC Strasbourg more than 10 years ago, motivated by the needs for vertex detectors at the International Linear Collider (ILC) [R. Turchetta et al, NIM A 458 (2001) 677]. Since then several other applications emerged. The first real scale digital CMOS sensor MIMOSA26 equips Flavour Tracker at RHIC, as well as for the microvertex detector of the CBM experiment at FAIR. MIMOSA sensors may also offer attractive performances for the ALICE upgrade at LHC. This paper will demonstrate the substantial performance improvement of CMOS sensors based on a high resistivity epitaxial layer. First studies for integrating the sensors into a detector system will be addressed and finally the way to go to a 10 μs readout sensor will be discussed.

  13. A flood map based DOI decoding method for block detector: a GATE simulation study.

    PubMed

    Shi, Han; Du, Dong; Su, Zhihong; Peng, Qiyu

    2014-01-01

    Positron Emission Tomography (PET) systems using detectors with Depth of Interaction (DOI) capabilities could achieve higher spatial resolution and better image quality than those without DOI. Up till now, most DOI methods developed are not cost-efficient for a whole body PET system. In this paper, we present a DOI decoding method based on flood map for low-cost conventional block detector with four-PMT readout. Using this method, the DOI information can be directly extracted from the DOI-related crystal spot deformation in the flood map. GATE simulations are then carried out to validate the method, confirming a DOI sorting accuracy of 85.27%. Therefore, we conclude that this method has the potential to be applied in conventional detectors to achieve a reasonable DOI measurement without dramatically increasing their complexity and cost of an entire PET system.

  14. Comparative studies on PADC polymeric detector treated by gamma radiation and Ar ion beam

    NASA Astrophysics Data System (ADS)

    El-Saftawy, A. A.; Abdel Reheem, A. M.; Kandil, S. A.; Abd El Aal, S. A.; Salama, S.

    2016-05-01

    In the present study, a comparative analysis and evaluation of the induced defects in polyallyl diglycol carbonate (PADC) polymeric detector exposed to Ar+ and gamma radiation were made. To get insight into the structure defects due to irradiation, X-ray diffraction (XRD) technique was employed. The PADC surface structure changed after irradiation due to the reduction in the surface crystalline structure and the formation of disordered systems. Also, surface morphology changes were traced using scanning electron microscopy (SEM) and showed minor surface irregularities after gamma irradiation and large changes upon Ar+ irradiation. Additionally, micro-hardness and friction coefficient of the irradiated samples were investigated and found to increase after irradiation. UV-vis spectroscopy was used to estimate the optical band gap energy which considered as the basis for calculating the number of conjugated carbon atoms responsible for the blackening effect and color changes took place over the PADC surface. It was found that as the applied dose increased, the band gap decreased and the number of carbon clusters get larger. The refractive index and the dispersion parameters for the studied polymer were calculated and discussed. Also, the induced defects on the polymer surface which serve as a non-radiative centers resulting in reduced photoluminescence (PL) intensity. For nearly all the measured parameters, gamma irradiated samples showed a significant changes compared to that induced by ions. But, low energy Ar+ prove efficiency in controlling surface properties of PADC polymer without affecting its sensitive bulk properties, besides that the obtained results are reasonable and comparable to that induced by gamma radiation.

  15. Study of Stent Deployment Mechanics Using a High-Resolution X-ray Imaging Detector

    PubMed Central

    Wang, Weiyuan; Ionita, Ciprian N; Bednarek, Daniel R; Rudin, Stephen

    2011-01-01

    To treat or prevent some of the 795,000 annual strokes in the U.S., self-expanding endo-vascular stents deployed under fluoroscopic image guidance are often used. Neuro-interventionalists need to know the deployment behavior of each stent in order to place them in the correct position. Using the Micro-Angiographic Fluoroscope (MAF) which has about 3 times higher resolution than commercially available flat panel detectors (FPD) we studied the deployment mechanics of two of the most important commercially available nitinol stents: the Pipeline embolization device (EV3), and the Enterprise stent (Codman). The Pipeline stent's length extends to about 3 times that of its deployed length when it is contained inside a catheter. From the high-resolution images with the MAF we found that upon the sudden release of the distal end of the Pipeline from a helical wire cap, the stent expands radially but retracts to about 30% (larger than for patient deployments) of its length. When released from the catheter proximally, it retracts additionally about 50% contributing to large uncertainty in the final deployed location. In contrast, the MAF images clearly show that the Enterprise stent self expands with minimal length retraction during deployment from its catheter and can be retrieved and repositioned until the proximal markers are released from clasping structures on its guide-wire thus enabling more accurate placement at the center of an aneurysm or stenosis. The high-resolution imaging demonstrated in this study should help neurointerventionalists understand and control endovascular stent deployment mechanisms and hence perform more precise treatments. PMID:21804747

  16. Study of quasi-elastic scattering in the NOνA near detector prototype

    SciTech Connect

    Betancourt, M.

    2015-05-15

    NOvA is a 14 kTon long-baseline neutrino oscillation experiment currently being installed in the NuMI off-axis neutrino beam produced at Fermilab. A 222 Ton prototype NOνA detector was built and operated in the neutrino beam for over a year to understand the response of the detector and its construction. Muon neutrino interaction data collected in this test are being analyzed to identify quasi-elastic charged-current interactions and measure the behavior of the quasi-elastic muon neutrino cross section.

  17. Operational Studies of Cadmium Zinc Telluride Microstrip Detectors using SVX ASIC Electronics

    NASA Astrophysics Data System (ADS)

    Krizmanic, John; Barbier, L. M.; Barthelmy, S.; Bartlett, L.; Birsa, F.; Gehrels, N.; Hanchak, C.; Kurczynski, P.; Odom, J.; Parsons, A.; Palmer, D.; Sheppard, D.; Snodgrass, S.; Stahle, C. M.; Teegarden, B.; Tueller, J.

    1997-04-01

    We have been investigating the operational properties of cadmium zinc telluride (CZT) microstrip detectors by using SVX ASIC readout electronics. This research is in conjunction with the development of a CZT-based, next generation gamma-ray telescope for use in the gamma-ray Burst ArcSecond Imaging and Spectroscopy (BASIS) experiment. CZT microstrip detectors with 128 channels and 100 micron strip pitch have been fabricated and were interfaced to SVX electronics at Goddard Space Flight Center. Experimental results involving position sensing, spectroscopy, and CZT operational properties will be presented.

  18. Smoke Detector

    NASA Technical Reports Server (NTRS)

    1979-01-01

    In the photo, Fire Chief Jay Stout of Safety Harbor, Florida, is explaining to young Richard Davis the workings of the Honeywell smoke and fire detector which probably saved Richard's life and that of his teen-age brother. Alerted by the detector's warning, the pair were able to escape their burning home. The detector in the Davis home was one of 1,500 installed in Safety Harbor residences in a cooperative program conducted by the city and Honeywell Inc.

  19. Recent developments in transition-edge strip detectors for solar x-rays

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

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

  20. GATE simulation of a LYSO-based SPECT imager: Validation and detector optimization

    NASA Astrophysics Data System (ADS)

    Li, Suying; Zhang, Qiushi; Xie, Zhaoheng; Liu, Qi; Xu, Baixuan; Yang, Kun; Li, Changhui; Ren, Qiushi

    2015-02-01

    This paper presents a small animal SPECT system that is based on cerium doped lutetium-yttrium oxyorthosilicate (LYSO) scintillation crystal, position sensitive photomultiplier tubes (PSPMTs) and parallel hole collimator. Spatial resolution test and animal experiment were performed to demonstrate the imaging performance of the detector. Preliminary results indicated a spatial resolution of 2.5 mm at FWHM that cannot meet our design requirement. Therefore, we simulated this gamma camera using GATE (GEANT 4 Application for Tomographic Emission) aiming to make detector spatial resolution less than 2 mm. First, the GATE simulation process was validated through comparison between simulated and experimental data. This also indicates the accuracy and effectiveness of GATE simulation for LYSO-based gamma camera. Then the different detector sampling methods (crystal size with 1.5, and 1 mm) and collimator design (collimator height with 30, 34.8, 38, and 43 mm) were studied to figure out an optimized parameter set. Detector sensitivity changes were also focused on with different parameters set that generated different spatial resolution results. Tradeoff curves of spatial resolution and sensitivity were plotted to determine the optimal collimator height with different sampling methods. Simulation results show that scintillation crystal size of 1 mm and collimator height of 38 mm, which can generate a spatial resolution of ~1.8 mm and sensitivity of ~0.065 cps/kBq, can be an ideal configuration for our SPECT imager design.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  2. SEX-DETector: A Probabilistic Approach to Study Sex Chromosomes in Non-Model Organisms.

    PubMed

    Muyle, Aline; Käfer, Jos; Zemp, Niklaus; Mousset, Sylvain; Picard, Franck; Marais, Gabriel Ab

    2016-01-01

    We propose a probabilistic framework to infer autosomal and sex-linked genes from RNA-seq data of a cross for any sex chromosome type (XY, ZW, and UV). Sex chromosomes (especially the non-recombining and repeat-dense Y, W, U, and V) are notoriously difficult to sequence. Strategies have been developed to obtain partially assembled sex chromosome sequences. Most of them remain difficult to apply to numerous non-model organisms, either because they require a reference genome, or because they are designed for evolutionarily old systems. Sequencing a cross (parents and progeny) by RNA-seq to study the segregation of alleles and infer sex-linked genes is a cost-efficient strategy, which also provides expression level estimates. However, the lack of a proper statistical framework has limited a broader application of this approach. Tests on empirical Silene data show that our method identifies 20-35% more sex-linked genes than existing pipelines, while making reliable inferences for downstream analyses. Approximately 12 individuals are needed for optimal results based on simulations. For species with an unknown sex-determination system, the method can assess the presence and type (XY vs. ZW) of sex chromosomes through a model comparison strategy. The method is particularly well optimized for sex chromosomes of young or intermediate age, which are expected in thousands of yet unstudied lineages. Any organisms, including non-model ones for which nothing is known a priori, that can be bred in the lab, are suitable for our method. SEX-DETector and its implementation in a Galaxy workflow are made freely available. PMID:27492231

  3. Study and optimization of positioning algorithms for monolithic PET detectors blocks

    NASA Astrophysics Data System (ADS)

    Garcia de Acilu, P.; Sarasola, I.; Canadas, M.; Cuerdo, R.; Rato Mendes, P.; Romero, L.; Willmott, C.

    2012-06-01

    We are developing a PET insert for existing MRI equipment to be used in clinical PET/MR studies of the human brain. The proposed scanner is based on annihilation gamma detection with monolithic blocks of cerium-doped lutetium yttrium orthosilicate (LYSO:Ce) coupled to magnetically-compatible avalanche photodiodes (APD) matrices. The light distribution generated on the LYSO:Ce block provides the impinging position of the 511 keV photons by means of a positioning algorithm. Several positioning methods, from the simplest Anger Logic to more sophisticate supervised-learning Neural Networks (NN), can be implemented to extract the incidence position of gammas directly from the APD signals. Finally, an optimal method based on a two-step Feed-Forward Neural Network has been selected. It allows us to reach a resolution at detector level of 2 mm, and acquire images of point sources using a first BrainPET prototype consisting of two monolithic blocks working in coincidence. Neural networks provide a straightforward positioning of the acquired data once they have been trained, however the training process is usually time-consuming. In order to obtain an efficient positioning method for the complete scanner it was necessary to find a training procedure that reduces the data acquisition and processing time without introducing a noticeable degradation of the spatial resolution. A grouping process and posterior selection of the training data have been done regarding the similitude of the light distribution of events which have one common incident coordinate (transversal or longitudinal). By doing this, the amount of training data can be reduced to about 5% of the initial number with a degradation of spatial resolution lower than 10%.

  4. SEX-DETector: A Probabilistic Approach to Study Sex Chromosomes in Non-Model Organisms

    PubMed Central

    Muyle, Aline; Käfer, Jos; Zemp, Niklaus; Mousset, Sylvain; Picard, Franck; Marais, Gabriel AB

    2016-01-01

    We propose a probabilistic framework to infer autosomal and sex-linked genes from RNA-seq data of a cross for any sex chromosome type (XY, ZW, and UV). Sex chromosomes (especially the non-recombining and repeat-dense Y, W, U, and V) are notoriously difficult to sequence. Strategies have been developed to obtain partially assembled sex chromosome sequences. Most of them remain difficult to apply to numerous non-model organisms, either because they require a reference genome, or because they are designed for evolutionarily old systems. Sequencing a cross (parents and progeny) by RNA-seq to study the segregation of alleles and infer sex-linked genes is a cost-efficient strategy, which also provides expression level estimates. However, the lack of a proper statistical framework has limited a broader application of this approach. Tests on empirical Silene data show that our method identifies 20–35% more sex-linked genes than existing pipelines, while making reliable inferences for downstream analyses. Approximately 12 individuals are needed for optimal results based on simulations. For species with an unknown sex-determination system, the method can assess the presence and type (XY vs. ZW) of sex chromosomes through a model comparison strategy. The method is particularly well optimized for sex chromosomes of young or intermediate age, which are expected in thousands of yet unstudied lineages. Any organisms, including non-model ones for which nothing is known a priori, that can be bred in the lab, are suitable for our method. SEX-DETector and its implementation in a Galaxy workflow are made freely available. PMID:27492231

  5. SEX-DETector: A Probabilistic Approach to Study Sex Chromosomes in Non-Model Organisms.

    PubMed

    Muyle, Aline; Käfer, Jos; Zemp, Niklaus; Mousset, Sylvain; Picard, Franck; Marais, Gabriel Ab

    2016-01-01

    We propose a probabilistic framework to infer autosomal and sex-linked genes from RNA-seq data of a cross for any sex chromosome type (XY, ZW, and UV). Sex chromosomes (especially the non-recombining and repeat-dense Y, W, U, and V) are notoriously difficult to sequence. Strategies have been developed to obtain partially assembled sex chromosome sequences. Most of them remain difficult to apply to numerous non-model organisms, either because they require a reference genome, or because they are designed for evolutionarily old systems. Sequencing a cross (parents and progeny) by RNA-seq to study the segregation of alleles and infer sex-linked genes is a cost-efficient strategy, which also provides expression level estimates. However, the lack of a proper statistical framework has limited a broader application of this approach. Tests on empirical Silene data show that our method identifies 20-35% more sex-linked genes than existing pipelines, while making reliable inferences for downstream analyses. Approximately 12 individuals are needed for optimal results based on simulations. For species with an unknown sex-determination system, the method can assess the presence and type (XY vs. ZW) of sex chromosomes through a model comparison strategy. The method is particularly well optimized for sex chromosomes of young or intermediate age, which are expected in thousands of yet unstudied lineages. Any organisms, including non-model ones for which nothing is known a priori, that can be bred in the lab, are suitable for our method. SEX-DETector and its implementation in a Galaxy workflow are made freely available.

  6. Studying radiation hardness of a cadmium tungstate crystal based radiation detector

    NASA Astrophysics Data System (ADS)

    Shtein, M. M.; Smekalin, L. F.; Stepanov, S. A.; Zatonov, I. A.; Tkacheva, T. V.; Usachev, E. Yu

    2016-06-01

    The given article considers radiation hardness of an X-ray detector used in production of non-destructive testing instruments and inspection systems. In the course of research, experiments were carried out to estimate radiation hardness of a detector based on cadmium tungstate crystal and its structural components individually. The article describes a layout of an experimental facility that was used for measurements of radiation hardness. The radiation dose dependence of the photodiode current is presented, when it is excited by a light flux of a scintillator or by an external light source. Experiments were carried out to estimate radiation hardness of two types of optical glue used in detector production; they are based on silicon rubber and epoxy. With the help of a spectrophotometer and cobalt gun, each of the glue samples was measured for a relative light transmission factor with different wavelengths, depending on the radiation dose. The obtained data are presented in a comprehensive analysis of the results. It was determined, which of the glue samples is most suitable for production of detectors working under exposure to strong radiation.

  7. Cosmic-Ray Studies with an Alpha Magnetic Spectrometer (AMS Detector) on the International Space Station

    SciTech Connect

    Plyaskin, V.V.

    2005-01-01

    A brief description of the physics research program implemented with an alpha magnetic spectrometer (AMS detector) by a large-scale international collaboration on board the International Space Station is presented. The features of the experimental facility under construction are given, along with some results obtained during the test flight of the prototype spectrometer on board a space shuttle.

  8. Study on the technology of mutual alignment based on the four-quadrant photo electric detector

    NASA Astrophysics Data System (ADS)

    Hu, Ya-bin; Wang, Miao

    2015-11-01

    Panoramic stereo cameras and laser radars have their own coordinate system in the dynamic spatial sensing area and they have to determine the position relationship between each other through joint calibration. As using the traditional technology of mutual alignment based on the telescope cross wire is tedious and requires high operating skills, a new method of mutual alignment using lasers and four-quadrant photo electric detectors is provided after analyzing the working principle of four-quadrant photo electric detectors. Firstly make the laser beam irradiate the active area of the four-quadrant photo electric detector through coarse aiming. Then the center of a light spot offset relative to the center of the active area can be obtained according to the output voltage of four quadrants. The pose of two instruments can be adjusted properly to realize mutual alignment. The experimental results indicate that the alignment accuracy of four-quadrant detectors can meet the requirements of mutual alignment, which provides a new idea for joint calibration.

  9. Study of wavelength-shifting chemicals for use in large-scale water Cherenkov detectors

    SciTech Connect

    Sweany, M; Bernstein, A; Dazeley, S; Dunmore, J; Felde, J; Svoboda, R; Tripathi, S M

    2011-09-21

    Cherenkov detectors employ various methods to maximize light collection at the photomultiplier tubes (PMTs). These generally involve the use of highly reflective materials lining the interior of the detector, reflective materials around the PMTs, or wavelength-shifting sheets around the PMTs. Recently, the use of water-soluble wavelength-shifters has been explored to increase the measurable light yield of Cherenkov radiation in water. These wave-shifting chemicals are capable of absorbing light in the ultravoilet and re-emitting the light in a range detectable by PMTs. Using a 250 L water Cherenkov detector, we have characterized the increase in light yield from three compounds in water: 4-Methylumbelliferone, Carbostyril-124, and Amino-G Salt. We report the gain in PMT response at a concentration of 1 ppm as: 1.88 {+-} 0.02 for 4-Methylumbelliferone, stable to within 0.5% over 50 days, 1.37 {+-} 0.03 for Carbostyril-124, and 1.20 {+-} 0.02 for Amino-G Salt. The response of 4-Methylumbelliferone was modeled, resulting in a simulated gain within 9% of the experimental gain at 1 ppm concentration. Finally, we report an increase in neutron detection performance of a large-scale (3.5 kL) gadolinium-doped water Cherenkov detector at a 4-Methylumbelliferone concentration of 1 ppm.

  10. First-principles study of γ-ray detector materials in perovskite halides

    NASA Astrophysics Data System (ADS)

    Im, Jino; Jin, Hosub; Stoumpos, Constantinos; Chung, Duck; Liu, Zhifu; Peters, John; Wessels, Bruce; Kanatzidis, Mercouri; Freeman, Arthur

    2013-03-01

    In an effort to search for good γ-ray detector materials, perovskite halide compounds containing heavy elements were investigated. Despite the three-dimensional network of the corner shared octahedra and the extended nature of the outermost shell, its strong ionic character leads to a large band gap, which is one of the essential criteria for γ-ray detector materials. Thus, considering high density and high atomic number, these pervoskite halides are possible candidate for γ-ray detector materials. We performed first-principles calculations to investigate electronic structures and thermodynamic properties of intrinsic defects in the selected perovskite halide, CsPbBr3. The screened-exchange local density approximation scheme was employed to correct the underestimation of the band gap in the LDA method. As a result, the calculated band gap of CsPbBr3 is found to be suitable for γ-ray detection. Furthermore, defect formation energy calculations allow us to predict thermodynamic and electronic properties of possible intrinsic defects, which affect detector efficiency and energy resolution. Supported by the office of Nonproliferation and Verification R &D under Contract No. DE-AC02-06CH11357

  11. Background studies for NaI(Tl) detectors in the ANAIS dark matter project

    SciTech Connect

    Amaré, J.; Borjabad, S.; Cebrián, S.; Cuesta, C.; Fortuño, D.; García, E.; Ginestra, C.; Gómez, H.; Martínez, M.; Oliván, M. A.; Ortigoza, Y.; Solórzano, A. Ortiz de; Pobes, C.; Puimedón, J.; Sarsa, M. L.; Villar, J. A.; Villar, P.

    2013-08-08

    Several large NaI(Tl) detectors, produced by different companies, have been operated in the Canfranc Underground Laboratory (LSC) in the frame of the ANAIS (Annual modulation with NaI Scintillators) project devoted to the direct detection of dark matter. A complete background model has been developed for a 9.6 kg detector (referred as ANAIS-0 prototype) after a long data taking at LSC. Activities from the natural chains of {sup 238}U and {sup 232}Th, and {sup 40}K in the NaI(Tl) crystal were evaluated applying different methods: discrimination of alpha particles vs beta/gamma background by Pulse Shape Analysis for quantifying the content of the natural chains and coincidence techniques for {sup 40}K. Radioactive contaminations in the detector and shielding components were also determined by HPGe spectrometry. Monte Carlo simulations using Geant4 package were carried out to evaluate their contribution. At high energies, most of the measured background is nicely reproduced; at low energy some non-explained components are still present, although some plausible background sources have been analyzed. The {sup 40}K content of the NaI(Tl) crystal has been confirmed to be the dominant contributor to the measured background with this detector. In addition, preliminary results of the background characterization, presently underway at the LSC, of two recently produced NaI(Tl) detectors, with 12.5 kg mass each, will be presented: cosmogenic induced activity has been clearly observed and is being quantified, and {sup 40}K activity at a level ten times lower than in ANAIS-0 has been determined.

  12. An engineering design study of the support platform assembly for the SSC SDC detector

    SciTech Connect

    Krebs, H.J.; Western, J.L. ); Wands, R.H. )

    1993-04-01

    A large angular acceptance high energy physics particle detector is presently being designed by the Solenoidal Detector Collaboration for the purposes of doing high pt physics at the Superconducting Super Collider Laboratory. The support platform assembly is the structural device which transfers the 30,000 tonne gravitational load of the octagonally shaped muon barrel toroid and the other detector components to the foundation below. The detector components are very sensitive to differential deflection and rely on the barrel toroid and support platform for stability. The operational load path is provided by two pairs of inclined longitudinal plates resting at 67.5[degree] on three pairs of plate girders that are positioned in-line in Z. The plate girders are held together laterally with 38 tie bars and supported vertically by the vertical adjustment system. The lateral stability of the inclined plates is provided by 22 stabilizer beams with cross bracing between each beam. The Z location of each split in the plate girder is coincident with the Z location of the gap in the calorimeter (4428 nun from the detector center.) The width of each split is 155 mm to allow installation of the alignment reference system. The collider beam line in the IR-8 underground experimental hall is oriented at a 2.16 mm/m slope from south to north as shown in Figure 2. The support is designed and installed to provide this slope at the top surface of the inclined plates. The assembled support rests on a ten foot thick steel reinforced 8000 psi concrete slab. The slab has a 2 mm differential deflection criteria under nominal gravitational loading.

  13. Laser diode edge sensors for adaptive optics segmented arrays: Part 1--external cavity coupling and detector current

    NASA Astrophysics Data System (ADS)

    Remo, John L.

    1994-05-01

    An analytical study of laser diode (LD) operation coupled to external cavity scattering elements, which function as variably coupling reflectors (VCRs), is carried out with the purpose of determining the interrelationship between cavity coupling and intracavity optical intensity which determine the current generated at the rear facet PIN detector. If the external cavity coupling is position sensitive it can allow the relative position between the LD and the external cavity to be determined from the PIN or other detector mounted with the LD. If the LD and external cavity element are placed on opposite edges of two adjacent adaptive optics segments they can provide the basis for a self aligning position sensor; the amount of current detected at the PIN or other detector will depend on the relative displacement between the LD and external coupling element. Schematics of the edge sensors, the basic electronic configuration, and the optics of the external cavity are given. The ratio of the internal cavity intensity, Ic, to the saturation intensity, Is, is plotted as a function of the external cavity coupling. When this ratio approaches one, large-signal output is not a linear function of large-signal output. For operation well below saturation, the PIN detector current is directly related to Ic and may serve as a reliable detector.

  14. Improving depiction of temporal bone anatomy with low-radiation dose CT by an integrated circuit detector in pediatric patients: a preliminary study.

    PubMed

    He, Jingzhen; Zu, Yuliang; Wang, Qing; Ma, Xiangxing

    2014-12-01

    The purpose of this study was to determine the performance of low-dose computed tomography (CT) scanning with integrated circuit (IC) detector in defining fine structures of temporal bone in children by comparing with the conventional detector. The study was performed with the approval of our institutional review board and the patients' anonymity was maintained. A total of 86 children<3 years of age underwent imaging of temporal bone with low-dose CT (80 kV/150 mAs) equipped with either IC detector or conventional discrete circuit (DC) detector. The image noise was measured for quantitative analysis. Thirty-five structures of temporal bone were further assessed and rated by 2 radiologists for qualitative analysis. κ Statistics were performed to determine the agreement reached between the 2 radiologists on each image. Mann-Whitney U test was used to determine the difference in image quality between the 2 detector systems. Objective analysis showed that the image noise was significantly lower (P<0.001) with the IC detector than with the DC detector. The κ values for qualitative assessment of the 35 fine anatomical structures revealed high interobserver agreement. The delineation for 30 of the 35 landmarks (86%) with the IC detector was superior to that with the conventional DC detector (P<0.05) although there were no differences in the delineation of the remaining 5 structures (P>0.05). The low-dose CT images acquired with the IC detector provide better depiction of fine osseous structures of temporal bone than that with the conventional DC detector.

  15. Study of Nuclei far From Stability by Using the CHIMERA 4{pi} Detector and Radioactive Beams at LNS

    SciTech Connect

    Cardella, G.; De Filippo, E.; Pagano, A.; Papa, M.; Pirrone, S.; Verde, G.; Amorini, F.; Anzalone, A.; Maiolino, C.; Auditore, L.; Loria, D.; Trifiro, A.; Trimarchi, M.; Cavallaro, S.; Lombardo, I.; Porto, F.; Rizzo, F.; Russotto, P.; Chatterjee, M. B.; Geraci, E.

    2009-08-26

    At LNS are available radioactive beams at tandem and intermediate energies provided respectively by the EXCYT and by the fragmentation FRIBS facilities. Using these beams, and the 4{pi} detector CHIMERA, we want to study excitation and decay of resonances in light exotic nuclei populated with pick-up stripping and other reaction mechanisms. Some preliminary results obtained with stable and unstable beams are reported.

  16. Results from the characterisation of Advanced GAmma Tracking Array prototype detectors and their consequences for the next-generation nuclear physics spectrometer

    NASA Astrophysics Data System (ADS)

    Dimmock, M. R.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Nelson, L.; Nolan, P.; Rigby, S.; Unsworth, C.; Lazarus, I.; Simpson, J.; Medina, P.; Parisel, C.; Santos, C.

    2007-09-01

    The Advanced GAmma Tracking Array (AGATA) is a European project that is aiming to construct a complete 4π High Purity Germanium (HPGe) gamma-ray spectrometer for nuclear structure studies at future Radioactive Ion Beam (RIB) Facilities. The proposed array will utilise digital electronics, Pulse Shape Analysis (PSA) and Gamma-Ray Tracking (GRT) algorithms, to overcome the limited efficiencies encountered by current Escape Suppressed Spectrometers (ESS), whilst maintaining the high Peak-to-Total ratio. Two AGATA symmetrical segmented Canberra Eurisys (CE) prototype HPGe detectors have been tested at the University of Liverpool. A highly collimated Cs-137 (662keV) beam was raster scanned across each detector and data were collected in both singles and coincidence modes. The charge sensitive preamplifier output pulse shapes from all 37 channels (one for each of the 36 segments and one for the centre contact) were digitised and stored for offline analysis. The shapes of the real charge and image charge pulses have been studied to give detailed information on the position dependent response of each detector. 1mm position sensitivity has been achieved with the parameterisation of average pulse shapes, calculated from data collected with each of the detectors. The coincidence data has also been utilised to validate the electric field simulation code Multi Geometry Simulation (MGS). The precisely determined 3D interaction positions allow the comparison of experimental pulse shapes from single site interactions with those generated by the simulation. It is intended that the validated software will be used to calculate a basis data set of pulse shapes for the array, from which any interaction site can be determined through a χ2 minimisation of the digitized pulse with linear combinations of basis pulseshapes. The results from this partial validation, along with those from the investigation into the position sensitivity of each detector are presented.

  17. Optical Detectors

    NASA Astrophysics Data System (ADS)

    Goushcha, Alexander; Tabbert, Bernd

    Optical detectors are applied in all fields of human activities - from basic research to commercial applications in communication, automotive, medical imaging, homeland security, and other fields. The processes of light interaction with matter described in other chapters of this handbook form the basis for understanding the optical detectors physics and device properties.

  18. Optical Detectors

    NASA Astrophysics Data System (ADS)

    Tabbert, Bernd; Goushcha, Alexander

    Optical detectors are applied in all fields of human activities from basic research to commercial applications in communication, automotive, medical imaging, homeland security, and other fields. The processes of light interaction with matter described in other chapters of this handbook form the basis for understanding the optical detectors physics and device properties.

  19. A study of the effect of Al2O3 reflector on response function of NaI(Tl) detector

    NASA Astrophysics Data System (ADS)

    Tam, Hoang Duc; Chuong, Huynh Dinh; Thanh, Tran Thien; Van Tao, Chau

    2016-08-01

    This study aims to assess the effect of Al2O3 reflector surrounding the NaI(Tl) crystal on the detector response function, based on Monte Carlo simulation, which can verify the precise model of the NaI(Tl) detector. The method used in determining the suitable thickness of Al2O3 reflector is to compare the calculated and experimental values of full-energy peak efficiency. The results show that the Al2O3 reflector should have a thickness of 0.8-1.2 mm for the maximum deviation between the experimental and simulated efficiency of 3.2% at all concerning energies. In addition, the obtained results are in good agreement with the response function of simulation and experimental spectra.

  20. A bonding study toward the quality assurance of Belle-II silicon vertex detector modules

    NASA Astrophysics Data System (ADS)

    Kang, K. H.; Jeon, H. B.; Park, H.; Uozumi, S.; Adamczyk, K.; Aihara, H.; Angelini, C.; Aziz, T.; Babu, V.; Bacher, S.; Bahinipati, S.; Barberio, E.; Baroncelli, T.; Basith, A. K.; Batignani, G.; Bauer, A.; Behera, P. K.; Bergauer, T.; Bettarini, S.; Bhuyan, B.; Bilka, T.; Bosi, F.; Bosisio, L.; Bozek, A.; Buchsteiner, F.; Casarosa, G.; Ceccanti, M.; Červenkov, D.; Chendvankar, S. R.; Dash, N.; Divekar, S. T.; Doležal, Z.; Dutta, D.; Forti, F.; Friedl, M.; Hara, K.; Higuchi, T.; Horiguchi, T.; Irmler, C.; Ishikawa, A.; Joo, C. W.; Kandra, J.; Kato, E.; Kawasaki, T.; Kodyš, P.; Kohriki, T.; Koike, S.; Kolwalkar, M. M.; Kvasnička, P.; Lanceri, L.; Lettenbicher, J.; Mammini, P.; Mayekar, S. N.; Mohanty, G. B.; Mohanty, S.; Morii, T.; Nakamura, K. R.; Natkaniec, Z.; Negishi, K.; Nisar, N. K.; Onuki, Y.; Ostrowicz, W.; Paladino, A.; Paoloni, E.; Pilo, F.; Profeti, A.; Rao, K. K.; Rashevskaia, I.; Rizzo, G.; Rozanska, M.; Sandilya, S.; Sasaki, J.; Sato, N.; Schultschik, S.; Schwanda, C.; Seino, Y.; Shimizu, N.; Stypula, J.; Tanaka, S.; Tanida, K.; Taylor, G. N.; Thalmeier, R.; Thomas, R.; Tsuboyama, T.; Urquijo, P.; Vitale, L.; Volpi, M.; Watanuki, S.; Watson, I. J.; Webb, J.; Wiechczynski, J.; Williams, S.; Würkner, B.; Yamamoto, H.; Yin, H.; Yoshinobu, T.

    2016-09-01

    A silicon vertex detector (SVD) for the Belle-II experiment comprises four layers of double-sided silicon strip detectors (DSSDs), assembled in a ladder-like structure. Each ladder module of the outermost SVD layer has four rectangular and one trapezoidal DSSDs supported by two carbon-fiber ribs. In order to achieve a good signal-to-noise ratio and minimize material budget, a novel chip-on-sensor "Origami" method has been employed for the three rectangular sensors that are sandwiched between the backward rectangular and forward (slanted) trapezoidal sensors. This paper describes the bonding procedures developed for making electrical connections between sensors and signal fan-out flex circuits (i.e., pitch adapters), and between pitch adapters and readout chips as well as the results in terms of the achieved bonding quality and pull force.

  1. The growth and Raman scattering studies of TGSP crystal as the IR room temperature infrared detector

    NASA Astrophysics Data System (ADS)

    Malekfar, R.; Abbasi, B.

    2005-09-01

    The partial substitution of sulphate (SO42-) by phosphate (PO43-) in triglycine sulfate (TGS) single crystal can improve the properties of the TGS family crystal as room temperature infrared (IR) detector. Phosphoric acid (H3PO4)-doped triglycine sulfate (TGSP) single crystal has strong pyroelectric properties due to its high pyroelectric coefficient and reasonably low dielectric constant. This family of single crystals can grow easily and rapidly and are reasonably good uniform detectors in the electromagnetic region from UV to IR at room temperature and without using cryogenic cooling. TGSP single crystals were grown by saturated solution method. In order to investigate the detection sensitivity of the TGSP crystal, single crystals with different dopant concentration of phosphate (PO43-) ion were grown. A rather complete back-scattering Raman scattering spectra and hysteresis loops of the grown crystals were recorded and compared with each other. The Raman spectra and their assignments only will be reported here.

  2. A combined study of source, detector and matter non-standard neutrino interactions at DUNE

    NASA Astrophysics Data System (ADS)

    Blennow, Mattias; Choubey, Sandhya; Ohlsson, Tommy; Pramanik, Dipyaman; Raut, Sushant K.

    2016-08-01

    We simultaneously investigate source, detector and matter non-standard neutrino interactions at the proposed DUNE experiment. Our analysis is performed using a Markov Chain Monte Carlo exploring the full parameter space. We find that the sensitivity of DUNE to the standard oscillation parameters is worsened due to the presence of non-standard neutrino interactions. In particular, there are degenerate solutions in the leptonic mixing angle θ 23 and the Dirac CP-violating phase δ. We also compute the expected sensitivities at DUNE to the non-standard interaction parameters. We find that the sensitivities to the matter non-standard interaction parameters are substantially stronger than the current bounds (up to a factor of about 15). Furthermore, we discuss correlations between the source/detector and matter non-standard interaction parameters and find a degenerate solution in θ 23. Finally, we explore the effect of statistics on our results.

  3. PROSPECT Background Studies and Operation of Li-Loaded Liquid Scintillator Detectors at a Research Reactor

    NASA Astrophysics Data System (ADS)

    Langford, Thomas; Prospect Collaboration

    2015-04-01

    Segmented antineutrino detectors placed near compact research reactors provide an excellent opportunity to probe short-baseline neutrino oscillations and precisely measure the reactor antineutrino spectrum. PROSPECT is a phased experiment that will explore the favored reactor anomaly parameter space at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Lab. Measurements of the reactor correlated and ambient backgrounds will be presented, as well as a discussion of active and passive mitigation plans. A lithium-loaded liquid scintillator test detector is currently in operation at HFIR within a prototype shielding cave. Results from recent operation will be presented along with a discussion of their impact on PROSPECT. on behalf of the PROSPECT collaboration.

  4. Study of a detector system for high-energy astrophysical objects using a combination of plastic scintillator and MPPC

    NASA Astrophysics Data System (ADS)

    Nakaoka, Tatsuya; Mizuno, Tsunefumi; Takahashi, Hiromitsu; Fukazawa, Yasushi

    2016-09-01

    We have investigated a hard X-ray detector system using a combination of a plastic scintillator and multi-pixel photon counters (MPPC). Photomultiplier tubes (PMTs) have typically been adopted to read scintillators because of their high gain and large photoelectric surface, and studies on PMT and scintillator systems are well advanced. However, PMTs have limitations; for example, they are relatively large in size, require high voltage to operate, and cannot be used in strong magnetic fields. On the other hand, MPPCs do not have such limitations and instead possess high quantum efficiency and a large compact size. Therefore, we have studied a detector system that combines an MPPC with a plastic scintillator. The system is primarily intended to be used for polarization measurements of high-energy astrophysical objects. We achieved an energy threshold of as low as ~5 keV while operating the detector at low temperature (-10 °C), reading the signal with short integration time (50 ns), and using a low-noise MPPC. We also confirmed that the light yield of our MPPC+plastic scintillator system is comparable to that obtained using a conventional PMT to read the scintillator signal. Herein, we report test results and future prospects.

  5. Assessment study of infrared detector arrays for low-background astronomical research

    NASA Technical Reports Server (NTRS)

    Ando, K. J.

    1978-01-01

    The current state-of-the-art of infrared detector arrays employing charge coupled devices (CCD) or charge injection devices (CID) readout are assessed. The applicability, limitations and potentials of such arrays under the low-background astronomical observing conditions of interest for SIRFT (Shuttle Infrared Telescope Facility) are determined. The following are reviewed: (1) monolithic extrinsic arrays; (2) monolithic intrinsic arrays; (3) charge injection devices; and (4) hybrid arrays.

  6. Study of TFTR D-T neutron spectra using natural diamond detectors

    SciTech Connect

    Roquemore, A.L.; Krasilnikov, A.V., Gorelenkov, N.N.

    1996-12-31

    Three Natural Diamond Detector (NDD) based spectrometers have been used for neutron spectra measurement during Deuterium-Tritium (D-T) experiments using high power Neutral Beam Injection (NBI) and Ton Cyclotron Resonance Heating (ICRH) on the Tokamak Fusion Test Reactor (TFTR) in 1996. A 2-3 % energy resolution coupled with the high radiation resistance of NDDs (5 x 10{sup 14}n/cm{sup 2}) makes them ideal for measuring the D-T neutron spectra in the high radiation environment of TFTR tritium experiments. The compact size of the NDD made it possible to insert one of the detectors into one of the center channels of the TFTR multichannel neutron collimator to provide a vertical view perpendicular to the vessel midplane, Two other detectors were placed inside shields in TFTR test cell and provide measurements of the neutrons having angles of emission of 110- 180{degrees} and 60-12-{degrees} with respect to the direction of the plasma current. By using a 0.25 {mu}s shaping time of the Ortec 673 spectroscopy amplifier we were able to accumulate useful spectrometry data at count rates up to 1.5 x 10{sup 3} counts/sec. To model the D- T neutron spectra measured by each of three NDD`s the Neutron Source post TRANSP (NST) code and semi-analytical model were developed. A set of D-T and D-D plasmas is analyzed for the dynamics of D-T neutron spectral broadening for each of three NDD cones of view. The application of three NDD based D-T neutron -spectrometer array demonstrated the anisotropy of the ion distribution function. and provided a mature of the dynamics of the effective ion temperatures for each detector view, and determined the tangential velocity of resonant tritons during ICRH.

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

    PubMed Central

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

    2014-01-01

    Single Photon Emission Computed Tomography (SPECT) suffers limited efficiency due to the need for collimators. Collimator properties largely decide the data statistics and image quality. Various materials and configurations of collimators have been investigated in many years. The main thrust of our study is to evaluate the design of pixel-geometry-matching collimators to investigate their potential performances using Geant4 Monte Carlo simulations. Here, a pixel-geometry-matching collimator is defined as a collimator which is divided into the same number of pixels as the detector’s and the center of each pixel in the collimator is a one-to-one correspondence to that in the detector. The detector is made of Cadmium Zinc Telluride (CZT), which is one of the most promising materials for applications to detect hard X-rays and γ-rays due to its ability to obtain good energy resolution and high light output at room temperature. For our current project, we have designed a large-area, CZT-based gamma camera (20.192 cm×20.192 cm) with a small pixel pitch (1.60 mm). The detector is pixelated and hence the intrinsic resolution can be as small as the size of the pixel. Materials of collimator, collimator hole geometry, detection efficiency, and spatial resolution of the CZT detector combined with the pixel-matching collimator were calculated and analyzed under different conditions. From the simulation studies, we found that such a camera using rectangular holes has promising imaging characteristics in terms of spatial resolution, detection efficiency, and energy resolution. PMID:25378898

  8. Multi-Chroic Dual-Polarization Bolometric Detectors for Studies of the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Suzuki, A.; Arnold, K.; Edwards, J.; Engargiola, G.; Holzapfel, W.; Keating, B.; Lee, A. T.; Meng, X. F.; Myers, M. J.; O'Brient, R.; Quealy, E.; Rebeiz, G.; Richards, P. L.; Rosen, D.; Siritanasak, P.

    2014-09-01

    We are developing multi-chroic antenna-coupled Transition Edge Sensor (TES) bolometer detectors for Cosmic Microwave Background (CMB) polarimetry. Multi-chroic detectors increase focal plane area efficiency, and thus the mapping speed per focal plane area, and provide greater discrimination against polarized galactic foregrounds with no increase in weight or cryogenic cost. In each pixel, a silicon lens-coupled dual-polarized sinuous antenna collects photons over a two-octave frequency band. The antenna couples the broadband millimeter wave signal into microstrip transmission lines, and on-chip filter banks split the broadband signal into multiple frequency bands. Separate TES bolometers detect the power in each frequency band and linear polarization state. We will describe the design and performance of these devices and present optical data taken. Our measurements of dual-polarization pixels in multiple frequency bands show beams with percent-level ellipticity, and percent-level cross-polarization leakage. We will also describe the development of large arrays of these multi-chroic pixels. Finally, we will describe kilo-pixel arrays of these detectors planned for the future CMB experiments that will achieve unprecedented mapping speed.

  9. Comparison of two detector systems for cone beam CT small animal imaging - a preliminary study.

    PubMed

    Meng, Yang; Shaw, Chris C; Liu, Xinming; Altunbas, Mustafa C; Wang, Tianpeng; Chen, Lingyun; Tu, Shu-Ju; Kappadath, S Cheenu; Lai, Chao-Jen

    2006-03-01

    To compare two detector systems - one based on the charge-coupled device (CCD) and image amplifier, the other based on a-Si/CsI flat panel, for cone beam computed-tomography (CT) imaging of small animals.A high resolution, high framing rate detector system for the cone beam CT imaging of small animals was developed. The system consists of a 2048x3072x12 bit CCD optically coupled to an image amplifier and an x-ray phosphor screen. The CCD has an intrinsic pixel size of 12 mum but the effective pixel size can be adjusted through the magnification adjustment of the optical coupling systems. The system is used in conjunction with an x-ray source and a rotating stage for holding and rotating the scanned object in the cone beam CT imaging experiments. The advantages of the system include but are not limited to the ability to adjust the effective pixel size and to achieve extremely high spatial resolution and temporal resolution. However, the need to use optical coupling compromises the detective quanta efficiency (DQE) of the system. In this paper, the imaging characteristics of the system were presented and compared with those of an a-Si/CsI flat-panel detector system. PMID:18160972

  10. Comparison of two detector systems for cone beam CT small animal imaging - a preliminary study

    PubMed Central

    Meng, Yang; Shaw, Chris C.; Liu, Xinming; Altunbas, Mustafa C.; Wang, Tianpeng; Chen, Lingyun; Tu, Shu-Ju; Kappadath, S. Cheenu; Lai, Chao-Jen

    2007-01-01

    Purpose To compare two detector systems - one based on the charge-coupled device (CCD) and image amplifier, the other based on a-Si/CsI flat panel, for cone beam computed-tomography (CT) imaging of small animals. A high resolution, high framing rate detector system for the cone beam CT imaging of small animals was developed. The system consists of a 2048×3072×12 bit CCD optically coupled to an image amplifier and an x-ray phosphor screen. The CCD has an intrinsic pixel size of 12 μm but the effective pixel size can be adjusted through the magnification adjustment of the optical coupling systems. The system is used in conjunction with an x-ray source and a rotating stage for holding and rotating the scanned object in the cone beam CT imaging experiments. The advantages of the system include but are not limited to the ability to adjust the effective pixel size and to achieve extremely high spatial resolution and temporal resolution. However, the need to use optical coupling compromises the detective quanta efficiency (DQE) of the system. In this paper, the imaging characteristics of the system were presented and compared with those of an a-Si/CsI flat-panel detector system. PMID:18160972

  11. Color properties of the motion detectors projecting to the goldfish tectum: I. A color matching study.

    PubMed

    Maximov, Vadim; Maximova, Elena; Damjanović, Ilija; Maximov, Paul

    2014-09-01

    Responses of direction-selective and orientation-selective motion detectors were recorded extracellularly from the axon terminals of ganglion cells in the superficial layers of the tectum opticum of immobilized goldfish, Carassius gibelio (Bloch, 1782). Color stripes or edges moving on some color background (presented on the CRT monitor with known emission spectra of its phosphors) served as stimuli. It was shown that stimuli of any color can be more or less matched with the background by varying their intensities what is indicative of color blindness of the motion detectors. Sets of stimuli which matched the background proved to represent planes in the three-dimensional color space of the goldfish. A relative contribution of different types of cones to the spectral sensitivity was estimated according to orientation of the plane of color matches. The spectral sensitivity of any motion detector was shown to be determined mainly by long-wave cones with a weak negative (opponent) contributions of middle-wave and/or short-wave ones. This resulted in reduced sensitivity in the blue-green end of the spectrum, what may be considered as an adaptation to the aquatic environment where, because of the substantial light scattering of a blue-green light, acute vision is possible only in a red region of the spectrum.

  12. The PAMELA Transition Radiation Detector

    NASA Astrophysics Data System (ADS)

    Cafagna, Francesco

    A Transition Radiation Detector (TRD) has been developed for the PAMELA instrument. PAMELA is a satellite born magnetic spectrometer; its primary scientific objective is the study of antiparticles in cosmic rays. The TRD detector was developed to provide particle identification, in addition to calorimetric measurements. This detector is composed of 9 active layers made of proportional straw tubes, piled up with interleaved carbon fibers radiator layers. Detector description and test beam performances will be presented.

  13. Experiment definition and integration study for the accommodation of giant, passive detector of Exotic Particles In the Cosmic Rays (EPIC) payload on shuttle/spacelab missions

    NASA Technical Reports Server (NTRS)

    Price, P. B.

    1978-01-01

    The feasibility of the design, construction, launch and retrieval of a hinged 15 ft by 110 ft the platform containing an array of interleaved CR-39 and Lexan track-recording detectors to be placed into circular orbit by space shuttle is assessed. The total weight of the detector assembly plus supporting structure and accessories is 32,000 pounds. The modular construction permits as little as one fourth of the payload to be exposed at one time. The CR-39 detector has sensitivity adequate to detect and study cosmic rays ranging from minimum ionizing iron-group nuclei to the heaviest elements. The detectors will survive a one year exposure to trapped protons without losing their high resolution. Advantages include low cost, huge collecting power (approximately 150 sq m) as well as the high resolution previously attainable only with electronic detectors.

  14. Benchmarking the Geant4 full system simulation of an associated alpha-particle detector for use in a D-T neutron generator.

    PubMed

    Zhang, Xiaodong; Hayward, Jason P; Cates, Joshua W; Hausladen, Paul A; Laubach, Mitchell A; Sparger, Johnathan E; Donnald, Samuel B

    2012-08-01

    The position-sensitive alpha-particle detector used to provide the starting time and initial direction of D-T neutrons in a fast-neutron imaging system was simulated with a Geant4-based Monte Carlo program. The whole detector system, which consists of a YAP:Ce scintillator, a fiber-optic faceplate, a light guide, and a position-sensitive photo-multiplier tube (PSPMT), was modeled, starting with incident D-T alphas. The scintillation photons, whose starting time follows the distribution of a scintillation decay curve, were produced and emitted uniformly into a solid angle of 4π along the track segments of the alpha and its secondaries. Through tracking all photons and taking into account the quantum efficiency of the photocathode, the number of photoelectrons and their time and position distributions were obtained. Using a four-corner data reconstruction formula, the flood images of the alpha detector with and without optical grease between the YAP scintillator and the fiber-optic faceplate were obtained, which show agreement with the experimental results. The reconstructed position uncertainties of incident alpha particles for both cases are 1.198 mm and 0.998 mm respectively across the sensitive area of the detector. Simulation results also show that comparing with other faceplates composed of 500 μm, 300 μm, and 100 μm fibers, the 10-μm-fiber faceplate is the best choice to build the detector for better position performance. In addition, the study of the background originating inside the D-T generator suggests that for 500-μm-thick YAP:Ce coated with 1-μm-thick aluminum, and very good signal-to-noise ratio can be expected through application of a simple threshold.

  15. A study of atmospheric neutrino oscillation using the icecube deepcore detector

    NASA Astrophysics Data System (ADS)

    Gladstone, Laura

    The IceCube detector at the South Pole is a cubic-kilometer-scale neutrino detector designed to observe TeV-range charged particle secondaries from neutrino interactions, and thus do neutrino astronomy. As a main background to the search for astrophysical point sources of neutrinos, IceCube also observes muons and neutrinos from the atmospheric interactions of cosmic rays. By observing a spectrum of atmospheric neutrinos and comparing it to independent predictions of atmospheric fluxes with and without oscillations, IceCube can test various values of oscillation parameters. Neutrino oscillations have been observed experimentally for several decades; IceCube is the first experiment to extend this measurement to the 10-20 GeV energy range. An initial analysis has established that IceCube can see oscillations using the 79-string detector configuration ("IC79"), which was the first year of data that included the DeepCore detector. As a follow-up, this analysis uses a less restrictive event selection and thus a higher total event count, around 3,000 for one year of data. The fit is a Poisson likelihood fit of a two-dimensional rate histogram, using both oscillated length and observed energy. The arrival zenith angle of the muon is used as a proxy for oscillation length. The error contours are dominated by systematic effects more than by statistical limitations of the data. Major systematics include uncertainties in the atmospheric neutrino flux at high energies and uncertainties in the distribution of the cosmic ray muon background. This analysis was designed to produce limits on the mixing angle θ 23 that are competitive with other current experiments, although this is still uncertain as error analysis work is ongoing. Future work will further refine the event selection and systematic error analysis; the statistical methods and software used here are expected to become the IceCube oscillations standard. This thesis also includes background information about the

  16. Gaseous Detectors

    NASA Astrophysics Data System (ADS)

    Titov, Maxim

    Since long time, the compelling scientific goals of future high-energy physics experiments were a driving factor in the development of advanced detector technologies. A true innovation in detector instrumentation concepts came in 1968, with the development of a fully parallel readout for a large array of sensing elements - the Multi-Wire Proportional Chamber (MWPC), which earned Georges Charpak a Nobel prize in physics in 1992. Since that time radiation detection and imaging with fast gaseous detectors, capable of economically covering large detection volumes with low mass budget, have been playing an important role in many fields of physics. Advances in photolithography and microprocessing techniques in the chip industry during the past decade triggered a major transition in the field of gas detectors from wire structures to Micro-Pattern Gas Detector (MPGD) concepts, revolutionizing cell-size limitations for many gas detector applications. The high radiation resistance and excellent spatial and time resolution make them an invaluable tool to confront future detector challenges at the next generation of colliders. The design of the new micro-pattern devices appears suitable for industrial production. Novel structures where MPGDs are directly coupled to the CMOS pixel readout represent an exciting field allowing timing and charge measurements as well as precise spatial information in 3D. Originally developed for the high-energy physics, MPGD applications have expanded to nuclear physics, photon detection, astroparticle and neutrino physics, neutron detection, and medical imaging.

  17. A Monte Carlo study to measure the energy spectra of the primary heavy components at the knee using a new Tibet AS core detector array and a large underground muon detector array

    NASA Astrophysics Data System (ADS)

    Huang, J.; Shibata, M.; Chen, D.; Hotta, N.; Katayose, Y.; Ohnishi, M.; Saito, T.; Takita, M.; Yuda, T.

    The first phase experiment of the Tibet hybrid experiment to measure the energy spectrum of the light components (proton and helium) strongly suggested that the knee region should be dominated by heavy components. A new type of air shower core detector Tibet-YAC (Yangbajing Air shower Core detector) as well as Tibet-MD (a large underground muon detector array) are being planned. In this paper, the capability of the event-by-event measurement of the chemical components with use of the Tibet III+YAC+MD is investigated by means of an extensive Monte Carlo simulation in which the secondary particles are also propagated through the YAC + MD array. Our simulation shows that the new installation is powerful enough to study the chemical composition, and in particular, to obtain the energy spectrum of the major component at the knee.

  18. A study of the ability of the D0 detector to measure the single jet inclusive cross section

    SciTech Connect

    Astur, R.V.

    1992-12-31

    The D0 experiment began accumulating data at the Fermilab Tevatron in May of 1992. Protons are collided with antiprotons at {radical}s = 1.8 TeV and an expected peak luminosity of 5 {times} 10{sup 30} cm{sup {minus}2} sec{sup {minus}1}. The D0 detector is an all-purpose detector that will have exceptional jet reconstruction capabilities derived from superior calorimetry and nearly 4{pi} angular coverage. One of the many physics measurements that will be made at D0 is the inclusive jet cross section. Comparison of this cross section with theoretical predictions allows us to test the accuracy of the standard model of Quantum Chromodynamics (QCD). This comparison is usually in the form of a measurement of the differential cross section with respect to the transverse energy of the jet. The extended angular coverage of the D0 detector allows measurements of the differential cross section as a function of jet rapidity as well. Recently completed calculations of the next-to-leading-order contribution to the inclusive cross section result in predictions with reduced theoretical errors. In addition, recent fits to data from deep inelastic scattering and single photon experiments further restrict the quark and gluon structure functions of the proton which are necessary in the theoretical predictions of the cross section. It may be that an experimental measurement of the inclusive cross section would favor some of these fits over others. We have studied extensive computer simulations of both the Tevatron and the D0 detector in order to determine D0`s ability to reconstruct the inclusive cross section. We present a discussion of this analysis as presently understood.

  19. Study of a new design of p-N semiconductor detector array for nuclear medicine imaging by monte carlo simulation codes.

    PubMed

    Hajizadeh-Safar, M; Ghorbani, M; Khoshkharam, S; Ashrafi, Z

    2014-07-01

    Gamma camera is an important apparatus in nuclear medicine imaging. Its detection part is consists of a scintillation detector with a heavy collimator. Substitution of semiconductor detectors instead of scintillator in these cameras has been effectively studied. In this study, it is aimed to introduce a new design of P-N semiconductor detector array for nuclear medicine imaging. A P-N semiconductor detector composed of N-SnO2 :F, and P-NiO:Li, has been introduced through simulating with MCNPX monte carlo codes. Its sensitivity with different factors such as thickness, dimension, and direction of emission photons were investigated. It is then used to configure a new design of an array in one-dimension and study its spatial resolution for nuclear medicine imaging. One-dimension array with 39 detectors was simulated to measure a predefined linear distribution of Tc(99_m) activity and its spatial resolution. The activity distribution was calculated from detector responses through mathematical linear optimization using LINPROG code on MATLAB software. Three different configurations of one-dimension detector array, horizontal, vertical one sided, and vertical double-sided were simulated. In all of these configurations, the energy windows of the photopeak were ± 1%. The results show that the detector response increases with an increase of dimension and thickness of the detector with the highest sensitivity for emission photons 15-30° above the surface. Horizontal configuration array of detectors is not suitable for imaging of line activity sources. The measured activity distribution with vertical configuration array, double-side detectors, has no similarity with emission sources and hence is not suitable for imaging purposes. Measured activity distribution using vertical configuration array, single side detectors has a good similarity with sources. Therefore, it could be introduced as a suitable configuration for nuclear medicine imaging. It has been shown that using

  20. Study of a New Design of P-N Semiconductor Detector Array for Nuclear Medicine Imaging by Monte Carlo Simulation Codes

    PubMed Central

    Hajizadeh-Safar, M.; Ghorbani, M.; Khoshkharam, S.; Ashrafi, Z.

    2014-01-01

    Gamma camera is an important apparatus in nuclear medicine imaging. Its detection part is consists of a scintillation detector with a heavy collimator. Substitution of semiconductor detectors instead of scintillator in these cameras has been effectively studied. In this study, it is aimed to introduce a new design of P-N semiconductor detector array for nuclear medicine imaging. A P-N semiconductor detector composed of N-SnO2 :F, and P-NiO:Li, has been introduced through simulating with MCNPX monte carlo codes. Its sensitivity with different factors such as thickness, dimension, and direction of emission photons were investigated. It is then used to configure a new design of an array in one-dimension and study its spatial resolution for nuclear medicine imaging. One-dimension array with 39 detectors was simulated to measure a predefined linear distribution of Tc99_m activity and its spatial resolution. The activity distribution was calculated from detector responses through mathematical linear optimization using LINPROG code on MATLAB software. Three different configurations of one-dimension detector array, horizontal, vertical one sided, and vertical double-sided were simulated. In all of these configurations, the energy windows of the photopeak were ± 1%. The results show that the detector response increases with an increase of dimension and thickness of the detector with the highest sensitivity for emission photons 15-30° above the surface. Horizontal configuration array of detectors is not suitable for imaging of line activity sources. The measured activity distribution with vertical configuration array, double-side detectors, has no similarity with emission sources and hence is not suitable for imaging purposes. Measured activity distribution using vertical configuration array, single side detectors has a good similarity with sources. Therefore, it could be introduced as a suitable configuration for nuclear medicine imaging. It has been shown that using

  1. MS Detectors

    SciTech Connect

    Koppenaal, David W.; Barinaga, Charles J.; Denton, M Bonner B.; Sperline, Roger P.; Hieftje, Gary M.; Schilling, G. D.; Andrade, Francisco J.; Barnes IV., James H.

    2005-11-01

    Good eyesight is often taken for granted, a situation that everyone appreciates once vision begins to fade with age. New eyeglasses or contact lenses are traditional ways to improve vision, but recent new technology, i.e. LASIK laser eye surgery, provides a new and exciting means for marked vision restoration and improvement. In mass spectrometry, detectors are the 'eyes' of the MS instrument. These 'eyes' have also been taken for granted. New detectors and new technologies are likewise needed to correct, improve, and extend ion detection and hence, our 'chemical vision'. The purpose of this report is to review and assess current MS detector technology and to provide a glimpse towards future detector technologies. It is hoped that the report will also serve to motivate interest, prompt ideas, and inspire new visions for ion detection research.

  2. Monte Carlo design study for thick gas electron multiplier-based multi-element microdosimetric detector

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    To accomplish enhanced neutron dose response with high detection efficiency, a set of multi-element microdosimetric detectors were designed using THick Gas Electron Multiplier (THGEM). THGEM generates a strong electric field within microholes of a sub-millimeter thick insulator, which makes electron multiplication possible without the traditional anode wire electrodes. Owing to the absence of wire electrodes, the newly designed neutron dosemeters offer flexible and convenient fabrication in contrast to the traditional multi-element tissue-equivalent proportional counters. In order to investigate the dependence of the neutron dosimetric response and detection efficiency on detector design, five designs with a different number of gas cavities and an identical outer diameter of 5 cm were created. For each design, a Monte Carlo simulation was developed using the Geant4 code to calculate the deposited energy spectrum in the gas cavities for mono-energetic neutron beams ranging from 10 keV to 2 MeV. From the simulation results, the microdosimetric and the absorbed dose responses of each multi-element design were consistent with the responses of the conventional single cavity detector. The quality factor and the dose equivalent responses were subsequently obtained and showed reasonable agreement with the ideal values for neutron energies above 300 keV while underestimating in the lower energy region. The neutron detection efficiency of each design was analyzed in terms of the neutron counts per incident fluence and the counts per dose equivalent. As the number of the multi-element cavities increased, both efficiencies increased greatly. The efficiency of the highest cavity density with 61×9 multi-elements was on average 5.6 times higher than that of the single cavity design. The 37×7 design could be chosen as a reasonable compromise between the two conflicting requirements, high efficiency and convenience in fabrication.

  3. A study of CR-39 plastic charged-particle detector replacement by consumer imaging sensors

    NASA Astrophysics Data System (ADS)

    Plaud-Ramos, K. O.; Freeman, M. S.; Wei, W.; Guardincerri, E.; Bacon, J. D.; Cowan, J.; Durham, J. M.; Huang, D.; Gao, J.; Hoffbauer, M. A.; Morley, D. J.; Morris, C. L.; Poulson, D. C.; Wang, Zhehui

    2016-11-01

    Consumer imaging sensors (CIS) are examined for real-time charged-particle detection and CR-39 plastic detector replacement. Removing cover glass from CIS is hard if not impossible, in particular for the latest inexpensive webcam models. We show that 10-class CIS are sensitive to MeV and higher energy protons and α-particles by using a 90Sr β-source with its cover glass in place. Indirect, real-time, high-resolution detection is also feasible when combining CIS with a ZnS:Ag phosphor screen and optics. Noise reduction in CIS is nevertheless important for the indirect approach.

  4. Growth and study of triglycine sulfate (TGS) crystals in low-G for infrared detector applications

    NASA Technical Reports Server (NTRS)

    Lal, R. B.; Batra, A. K.; Aggarwal, M. D.; Wilcox, W. R.; Trolinger, J. D.

    1991-01-01

    Experiments on growth of TGS crystals using (010) and (001) oriented disc shape seeds in the low gravity environment aboard Spacelab-3 are presented. The holographic interferograms reconstructed on the ground demonstrated diffusion limited growth. The morphology of the crystals grown was similar to that of crystals grown on earth, except the faces were not fully developed and planar. The device quality of these crytals is considered to be comparable with the best crystals grown on earth. Better infrared detector characteristics were obtained by doping TGS with Cs and L-alanine simultaneously on the ground. Crystals grown on (010) poled seeds show improved morphology and pyroelectric properties.

  5. DETECTORS AND EXPERIMENTAL METHODS: Study of BESIII MUC offline software with cosmic-ray data

    NASA Astrophysics Data System (ADS)

    Liang, Yu-Tie; Mao, Ya-Jun; You, Zheng-Yun; Li, Wei-Dong; Bian, Jian-Ming; Cao, Guo-Fu; Cao, Xue-Xiang; Chen, Shen-Jian; Deng, Zi-Yan; Fu, Cheng-Dong; Gao, Yuan-Ning; Han, Lei; Han, Shao-Qing; He, Kang-Lin; He, Miao; Hu, Ji-Feng; Hu, Xiao-Wei; Huang, Bin; Huang, Xing-Tao; Jia, Lu-Kui; Ji, Xiao-Bin; Li, Hai-Bo; Liu, Bei-Jiang; Liu, Chun-Xiu; Liu, Huai-Min; Liu, Ying; Liu, Yong; Luo, Tao; Lu, Qi-Wen; Ma, Qiu-Mei; Ma, Xiang; Mao, Ze-Pu; Mo, Xiao-Hu; Ning, Fei-Peng; Ping, Rong-Gang; Qiu, Jin-Fa; Song, Wen-Bo; Sun, Sheng-Sen; Sun, Xiao-Dong; Sun, Yong-Zhao; Tian, Hao-Lai; Wang, Ji-Ke; Wang, Liang-Liang; Wen, Shuo-Pin; Wu, Ling-Hui; Wu, Zhi; Xie, Yu-Guang; Xu, Min; Yan, Jie; Yan, Liang; Yao, Jian; Yuan, Chang-Zheng; Yuan, Ye; Zhang, Chang-Chun; Zhang, Jian-Yong; Zhang, Lei; Zhang, Xue-Yao; Zhang, Yao; Zheng, Yang-Heng; Zhu, Yong-Sheng; Zou, Jia-Heng

    2009-07-01

    Cosmic-ray data of 90 M events have been collected and used for calibration, alignment as well as detector tuning. A special tracking algorithm for the BESIII muon counter is developed and verified with Monte-Carlo simulation and then further confirmed with the cosmic-ray data. The obtained strip resolutions are in good agreement with the design values. A new alignment approach for the BESIII muon counter is confirmed with the cosmic-ray data and proposed to be used in future analysis of experimental data.

  6. Study for a Design of Magnet System for the SPD Detector NICA LHEP JINR

    NASA Astrophysics Data System (ADS)

    Yudin, Ivan P.

    2016-02-01

    The choice of magnet system for the Spin Physics Detector of the NICA Collider of LHEP JINR is given. The inverse problem of magnetostatics is solved for a magnetic field of 0.5 tesla in the aperture a) ɸ 3 m x 5 m and b) ɸ 3 m x 6 m. We also discuss the design of the magnet with a field of 0.3 T. The paper presents the results obtained for the "warm" and SC versions of the magnetic system: currents (ampere-turns), the geometry (size) of the coil and the iron yoke, weight (on the whole and the individual elements), the magnet transportation and assembly.

  7. SU-C-BRD-06: Results From a 5 Patient in Vivo Rectal Wall Dosimetry Study Using Plastic Scintillation Detectors

    SciTech Connect

    Wootton, L; Kudchadker, R; Lee, A; Beddar, S

    2014-06-15

    Purpose: To evaluate the performance characteristics of plastic scintillation detectors (PSDs) in an in vivo environment for external beam radiation, and to establish the usefulness and ease of implementation of a PSD based in vivo dosimetry system for routine clinical use. Methods: A five patient IRB approved in vivo dosimetry study was performed. Five patients with prostate cancer were enrolled and PSDs were used to monitor rectal wall dose and verify the delivered dose for approximately two fractions each week over the course of their treatment (approximately fourteen fractions), resulting in a total of 142 in vivo measurements. A set of two PSDs was fabricated for each patient. At each monitored fraction the PSDs were attached to the anterior surface of an endorectal balloon used to immobilize the patient's prostate during treatment. A CT scan was acquired with a CTon- rails linear accelerator to localize the detectors and to calculate the dose expected to be delivered to the detectors. Each PSD acquired data in 10 second intervals for the duration of the treatment. The deviation between expected and measured cumulative dose was calculated for each detector for each fraction, and averaged over each patient and the patient population as a whole. Results: The average difference between expected dose and measured dose ranged from -3.3% to 3.3% for individual patients, with standard deviations between 5.6% and 7.1% for four of the patients. The average difference for the entire population was -0.4% with a standard deviation of 2.8%. The detectors were well tolerated by the patients and the system did not interrupt the clinical workflow. Conclusion: PSDs perform well as in vivo dosimeters, exhibiting good accuracy and precision. This, combined with the practicability of using such a system, positions the PSD as a strong candidate for clinical in vivo dosimetry in the future. This work supported in part by the National Cancer Institute through an R01 grant (CA120198

  8. Study of the response of plastic scintillation detectors in small-field 6 MV photon beams by Monte Carlo simulations

    PubMed Central

    Wang, Lilie L. W.; Beddar, Sam

    2011-01-01

    Purpose: To investigate the response of plastic scintillation detectors (PSDs) in a 6 MV photon beam of various field sizes using Monte Carlo simulations. Methods: Three PSDs were simulated: A BC-400 and a BCF-12, each attached to a plastic-core optical fiber, and a BC-400 attached to an air-core optical fiber. PSD response was calculated as the detector dose per unit water dose for field sizes ranging from 10×10 down to 0.5×0.5 cm2 for both perpendicular and parallel orientations of the detectors to an incident beam. Similar calculations were performed for a CC01 compact chamber. The off-axis dose profiles were calculated in the 0.5×0.5 cm2 photon beam and were compared to the dose profile calculated for the CC01 chamber and that calculated in water without any detector. The angular dependence of the PSDs’ responses in a small photon beam was studied. Results: In the perpendicular orientation, the response of the BCF-12 PSD varied by only 0.5% as the field size decreased from 10×10 to 0.5×0.5 cm2, while the response of BC-400 PSD attached to a plastic-core fiber varied by more than 3% at the smallest field size because of its longer sensitive region. In the parallel orientation, the response of both PSDs attached to a plastic-core fiber varied by less than 0.4% for the same range of field sizes. For the PSD attached to an air-core fiber, the response varied, at most, by 2% for both orientations. Conclusions: The responses of all the PSDs investigated in this work can have a variation of only 1%–2% irrespective of field size and orientation of the detector if the length of the sensitive region is not more than 2 mm long and the optical fiber stems are prevented from pointing directly to the incident source. PMID:21520871

  9. The cosmic ray muon tomography facility based on large scale MRPC detectors

    NASA Astrophysics Data System (ADS)

    Wang, Xuewu; Zeng, Ming; Zeng, Zhi; Wang, Yi; Zhao, Ziran; Yue, Xiaoguang; Luo, Zhifei; Yi, Hengguan; Yu, Baihui; Cheng, Jianping

    2015-06-01

    Cosmic ray muon tomography is a novel technology to detect high-Z material. A prototype of TUMUTY with 73.6 cm×73.6 cm large scale position sensitive MRPC detectors has been developed and is introduced in this paper. Three test kits have been tested and image is reconstructed using MAP algorithm. The reconstruction results show that the prototype is working well and the objects with complex structure and small size (20 mm) can be imaged on it, while the high-Z material is distinguishable from the low-Z one. This prototype provides a good platform for our further studies of the physical characteristics and the performances of cosmic ray muon tomography.

  10. Study on the influence of CR-39 detector size on radon progeny detection in indoor environments

    SciTech Connect

    Pereira, L. A.; Hadler, J. C.; Lixandrão F, A. L.; Guedes, S.; Takizawa, R. H.

    2014-11-11

    It is well known that radon daughters up to {sup 214}Po are the real contaminants to be considered in case of indoor radon contamination. Assemblies consisting of 6 circular bare sheets of CR-39, a nuclear track detector, with radius varying from 0.15 to 1.2 cm were exposed far from any material surface for periods of approximately 6 months in 13 different indoor rooms (7 workplaces and 6 dwellings), where ventilation was moderate or poor. It was observed that track density was as greater as smaller was the detector radius. Track density data were fitted using an equation deduced based on the assumption that the behavior of radon and its progeny in the air was described by Fick's Law, i.e., when the main mechanism of transport of radon progeny in the air is diffusion. As many people spend great part of their time in closed or poorly ventilated environments, the confirmation they present equilibrium between radon and its progeny is an interesting start for dosimetric calculations concerning this contamination.

  11. Study of the effect of NbN on microwave Niobium cavities for gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    Liccardo, V.; França, E. K.; Aguiar, O. D.; Oliveira, R. M.; Ribeiro, K. L.; Silva, M. M. N. F.

    2016-07-01

    Superconducting reentrant cavities may be used in parametric transducers for resonant-mass gravitational wave detectors. When coupled to a spherical resonant antenna, transducers will monitor its mechanical quadrupolar modes, working as a mass-spring system. In this paper we will investigate the effect of the Niobium Nitride (NbN), produced through plasma immersion ion implantation (PIII), on the quality factor of reentrant Niobium (Nb) cavities. With the PIII surface treatment unloaded electrical Q-factors (Q0) of the order of 105 were obtained in cryogenic conditions. These results indicated a significant increase in the effect of superconductivity after the cavity surfaces have been heavily attacked by a concentrated acid mixture and after suffering successive PIII processes. Q0's ~ 3.0 × 105 at 4.2 K are expected to be obtained using Nb RRR399 with a suitable surface treatment. These cavities, with high Q0, are already installed and being tested in the Gravitational Wave Detector Mario Schenberg. The experimental tests have been carried out at the laboratories of the National Institute for Space Research (INPE).

  12. Study on the influence of CR-39 detector size on radon progeny detection in indoor environments

    NASA Astrophysics Data System (ADS)

    Pereira, L. A.; Hadler, J. C.; Lixandrão F., A. L.; Guedes, S.; Takizawa, R. H.

    2014-11-01

    It is well known that radon daughters up to 214Po are the real contaminants to be considered in case of indoor radon contamination. Assemblies consisting of 6 circular bare sheets of CR-39, a nuclear track detector, with radius varying from 0.15 to 1.2 cm were exposed far from any material surface for periods of approximately 6 months in 13 different indoor rooms (7 workplaces and 6 dwellings), where ventilation was moderate or poor. It was observed that track density was as greater as smaller was the detector radius. Track density data were fitted using an equation deduced based on the assumption that the behavior of radon and its progeny in the air was described by Fick's Law, i.e., when the main mechanism of transport of radon progeny in the air is diffusion. As many people spend great part of their time in closed or poorly ventilated environments, the confirmation they present equilibrium between radon and its progeny is an interesting start for dosimetric calculations concerning this contamination.

  13. Primary study on the contact degradation mechanism of CdZnTe detectors

    NASA Astrophysics Data System (ADS)

    Sang, Wenbin; Wei, Jin; Qi, Zhang; Wanwan, Li; Jiahua, Min; Jianyong, Teng; Yongbiao, Qian

    2004-07-01

    The metal-CdZnTe (CZT) interface plays a vital role in determining the contact characteristics, which is often the dominant factor influencing detector performance. The effects of the degradation of the interfacial layer between the metal contact layer and CZT surface on the mechanical and electrical properties have been investigated in this paper. The interfacial thermal stresses were simulated using 3-D finite element method (FEM). The results indicate that the maximum thermal stress is concentrated on the midst of the electrode and the magnitude of the stress produced by the different electrode materials in order is Al>Au>Pt>In. The adhesion forces between the metal contact layer and CZT surface were measured by using a Dage PC2400 Micro tester with the shear-off-method. The inter-diffusion between the metal contact layer and CZT was identified using the Anger depth profiles. The experimental results indicate that the electroless Au electrode on p-type high resistivity CZT is of smaller interfacial adhesion strength, but of better ohmicity than the sputtered Au. In addition, the aging effects on the contact characteristics of the detector were also examined.

  14. Study of a Vuilleumier cycle cryogenic refrigerator for detector cooling on the limb scanning infrared radiometer

    NASA Technical Reports Server (NTRS)

    Russo, S. C.

    1976-01-01

    A program to detect and monitor the presence of trace constituents in the earth's atmosphere by using the Limb Scanning Infrared Radiometer (LSIR) is reported. The LSIR, which makes radiometric measurements of the earth's limb radiance profile from a space platform, contains a detector assembly that must be cooled to a temperature of 65 + or - 2 K. The feasibility of cooling the NASA-type detector package with Vuilleumier (VM) cryogenic refrigerator was investigated to develop a preliminary conceptual design of a VM refrigerator that is compatible with a flight-type LSIR instrument. The scope of the LSIR program consists of analytical and design work to establish the size, weight, power consumption, interface requirements, and other important characteristics of a cryogenic cooler that would meet the requirements of the LSIR. The cryogenic cooling requirements under the conditions that NASA specified were defined. Following this, a parametric performance analysis was performed to define the interrelationships between refrigeration characteristics and mission requirements. This effort led to the selection of an optimum refrigerator design for the LSIR mission.

  15. Some recent developments in nuclear charged particle detectors

    SciTech Connect

    Stelzer, H.

    1980-08-01

    The latest developments of large-area, position sensitive gas-filled ionization chambers are described. Multi-wire-proportional chambers as position-sensing and parallel-plate-avalanche counters as time-sensing detectors at low pressure (5 torr) have proven to be useful and reliable instruments in heavy ion physics. Gas (proportional) scintillation counters, used mainly for x-ray spectroscopy, have recently been applied as particle detectors. Finally, a brief description of a large plastic scintillator spectrometer, the Plastic Ball, is given and some of the first test and calibration data are shown.

  16. Advanced Gravitational Wave Detectors

    NASA Astrophysics Data System (ADS)

    Blair, D. G.; Howell, E. J.; Ju, L.; Zhao, C.

    2012-02-01

    Part I. An Introduction to Gravitational Wave Astronomy and Detectors: 1. Gravitational waves D. G. Blair, L. Ju, C. Zhao and E. J. Howell; 2. Sources of gravitational waves D. G. Blair and E. J. Howell; 3. Gravitational wave detectors D. G. Blair, L. Ju, C. Zhao, H. Miao, E. J. Howell, and P. Barriga; 4. Gravitational wave data analysis B. S. Sathyaprakash and B. F. Schutz; 5. Network analysis L. Wen and B. F. Schutz; Part II. Current Laser Interferometer Detectors: Three Case Studies: 6. The Laser Interferometer Gravitational-Wave Observatory P. Fritschel; 7. The VIRGO detector S. Braccini; 8. GEO 600 H. Lück and H. Grote; Part III. Technology for Advanced Gravitational Wave Detectors: 9. Lasers for high optical power interferometers B. Willke and M. Frede; 10. Thermal noise, suspensions and test masses L. Ju, G. Harry and B. Lee; 11. Vibration isolation: Part 1. Seismic isolation for advanced LIGO B. Lantz; Part 2. Passive isolation J-C. Dumas; 12. Interferometer sensing and control P. Barriga; 13. Stabilizing interferometers against high optical power effects C. Zhao, L. Ju, S. Gras and D. G. Blair; Part IV. Technology for Third Generation Gravitational Wave Detectors: 14. Cryogenic interferometers J. Degallaix; 15. Quantum theory of laser-interferometer GW detectors H. Miao and Y. Chen; 16. ET. A third generation observatory M. Punturo and H. Lück; Index.

  17. Momentum spectrometer for electron-electron coincidence studies on superconductors

    SciTech Connect

    Wallauer, Robert; Voss, Stefan; Bauer, Tobias; Schneider, Deborah; Titze, Jasmin; Ulrich, Birte; Kreidi, Katharina; Neumann, Nadine; Havermeier, Tilo; Schoeffler, Markus; Jahnke, Till; Czasch, Achim; Schmidt, Lothar; Schmidt-Boecking, Horst; Doerner, Reinhard; Kanigel, Amit; Campuzano, Juan Carlos; Jeschke, Harald; Valenti, Roser [Institut fuer Theoretische Physik, Universitaet Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt and others

    2012-10-15

    We present a new experimental setup to study electron-electron coincidences from superconducting surfaces. In our approach, electrons emitted from a surface are projected onto a time- and position-sensitive microchannel plate detector with delayline position readout. Electrons that are emitted within 2 {pi} solid angle with respect to the surface are detected in coincidence. The detector used is a hexagonal delayline detector with enhanced multiple hit capabilities. It is read out with a Flash analog-to-digital converter. The three-dimensional momentum vector is obtained for each electron. The intrinsic dead time of the detector has been greatly reduced by implementing a new algorithm for pulse analysis. The sample holder has been matched to fit the spectrometer while being capable of cooling down the sample to 4.5 K during the measurement and heating it up to 420 K for the cleaning procedure.

  18. Feasibility study of a dual detector configuration concept for simultaneous megavoltage imaging and dose verification in radiotherapy

    SciTech Connect

    Deshpande, Shrikant; McNamara, Aimee L.; Holloway, Lois; Metcalfe, Peter; Vial, Philip

    2015-04-15

    IMRT test patterns and clinical IMRT beams had gamma pass rates of ≥98% at 2%/2 mm criteria. In terms of imaging performance, the measured CNR and spatial resolution (f{sub 50}) were 263.23 ± 24.85 and 0.4025 ± 1.25 × 10{sup −3} for dual detector configuration and 324 ± 26.65 and 0.4141 ± 1.14 × 10{sup −3} for reference imaging configuration, respectively. The CNR and spatial resolution were quantitatively worse in the dual detector configuration due to the additional backscatter. The difference in imaging performance was not visible in qualitative assessment of phantom images. Conclusions: Combining a commercially available ICA dosimetry device with a conventional EPID did not significantly detract from the performance of either device. Further improvements in imaging performance may be achieved with an optimized design. This study demonstrates the feasibility of a dual detector concept for simultaneous imaging and dosimetry in radiation therapy.

  19. Scanning transient current study of the I-V stabilization phenomena in silicon detectors irradiated by fast neutrons

    SciTech Connect

    Eremin, V.; Verbitskaya, E.; Li, Z.; Sidorov, A.; Fretwurst, E.; Lindstrom, G.

    1996-03-01

    Investigation of the I-V stabilization phenomena in neutron irradiated silicon detectors has been carried out using scanning transient current technique (STCT) on non-irradiated PP{sup +}-p-n{sup +} detectors. The PP{sup +}-p-n{sup +} detectors were used to simulate the PP{sup +}-n-n{sup +} detectors irradiated beyond the space charge sign inversion (SCSI). Two mechanisms partially responsible for the I- V stabilization have been identified.

  20. Small-angle x-ray scattering/diffraction system for studies of biological and other materials at the Stanford Synchrotron Radiation Laboratorya)

    NASA Astrophysics Data System (ADS)

    Wakatsuki, S.; Hodgson, K. O.; Eliezer, D.; Rice, M.; Hubbard, S.; Gillis, N.; Doniach, S.; Spann, U.

    1992-02-01

    A versatile small-angle x-ray diffraction/scattering system has been developed at Stanford Synchrotron Radiation Laboratory for studies of biological and other materials. The system includes two sets of collimation slits separated by an ionization chamber, a sample holder cooled by a circulation bath, a vacuum/He scattering path after the sample holder and a detector, either a linear one-dimensional position-sensitive proportional counter or a position-sensitive quadrant detector. Data aquisition is controlled by a VAXstation through a CAMAC interface. Menu-driven data acquisition and on-line analysis software has been developed. The system can be used to collect small- to intermediate-angle x-ray scattering and diffraction data. Monochromatic, anomalous, and time-resolved scattering/diffraction experiments are possible. A time-resolved spectrophotometer using photodiode arrays has also been developed for simultaneous measurements of optical absorption spectra and x-ray scattering/diffraction.

  1. Small-angle x-ray scattering/diffraction system for studies of biological and other materials at the Stanford Synchrotron Radiation Laboratory (abstract)a)

    NASA Astrophysics Data System (ADS)

    Wakatsuki, S.; Hodgson, K. O.; Eliezer, D.; Rice, M.; Hubbard, S.; Gillis, N.; Doniach, S.; Spann, U.

    1992-01-01

    A versatile small-angle x-ray diffraction/scattering system has been developed at Stanford Synchrotron Radiation Laboratory for studies of biological and other materials. The system includes two sets of collimation slits separated by an ionization chamber, a sample holder cooled by a circulation bath, a vacuum/He scattering path after the sample holder and a detector, either a linear one-dimensional position-sensitive proportional counter or a position-sensitive quadrant detector. Data aquisition is controlled by a VAXstation through a CAMAC interface. Menu-driven data acquisition and on-line analysis software has been developed. The system can be used to collect small- to intermediate-angle x-ray scattering and diffraction data. Monochromatic, anomalous, and time-resolved diffraction/scattering experiments are possible. A time-resolved spectrophotometer using photodiode arrays has also been developed for simultaneous measurements of optical absorption spectra and x-ray scattering/diffraction.

  2. Photon detectors

    SciTech Connect

    Va`vra, J.

    1995-10-01

    J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF{sub 2} windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission.

  3. Sounding-rocket experiment to study the diffuse soft X-ray background using a Si(Li) detector

    NASA Technical Reports Server (NTRS)

    Delvaille, J. P.

    1981-01-01

    Soft X-ray background in the energy range 0.4 to 10 keV was studied. A payload was developed which uses a wide angle, windowless, cooled, Si(Li) semiconductor detector system. With a resolution of less than 150 eV between 0.3 and 2.0 keV, the system is sensitive to an emission equivalent width of about 10 eV. Carbon and oxygen line emission were detected from the vicinity of the North Galactic Pole and the North Polar Spur.

  4. First experimental charge density study using a Bruker CMOS-type PHOTON 100 detector: the case of ammonium tetraoxalate dihydrate.

    PubMed

    Jarzembska, Katarzyna N; Kamiński, Radosław; Dobrzycki, Lukasz; Cyrański, Michał K

    2014-10-01

    The aim of this study was to test the applicability of a Bruker AXS CMOS-type PHOTON 100 detector for the purpose of a fine charge density quality data collection. A complex crystal containing oxalic acid, ammonium oxalate and two water molecules was chosen as a test case. The data was collected up to a resolution of 1.31 Å(-1) with high completeness (89.1%; Rmrg = 0.0274). The multipolar refinement and subsequent quantum theory of atoms in molecules (QTAIM) analysis resulted in a comprehensive description of the charge density distribution in the crystal studied. The residual density maps are flat and almost featureless. It was possible to derive reliable information on intermolecular interactions to model the anharmonic motion of a water molecule, and also to observe the fine details of the charge density distribution, such as polarization on O and H atoms involved in the strongest hydrogen bonds. When compared with our previous statistical study on oxalic acid data collected with the aid of CCD cameras, the complementary metal-oxide semiconductor (CMOS) detector can certainly be classified as a promising alternative in advanced X-ray diffraction studies.

  5. Study of accuracy in the position determination with SALSA, a γ-scanning system for the characterization of segmented HPGe detectors

    NASA Astrophysics Data System (ADS)

    Hernandez-Prieto, A.; Quintana, B.; Martìn, S.; Domingo-Pardo, C.

    2016-07-01

    Accurate characterization of the electric response of segmented high-purity germanium (HPGe) detectors as a function of the interaction position is one of the current goals of the Nuclear Physics community seeking to perform γ-ray tracking or even imaging with these detectors. For this purpose, scanning devices must be developed to achieve the signal-position association with the highest precision. With a view to studying the accuracy achieved with SALSA, the SAlamanca Lyso-based Scanning Array, here we report a detailed study on the uncertainty sources and their effect in the position determination inside the HPGe detector to be scanned. The optimization performed on the design of SALSA, aimed at minimizing the effect of the uncertainty sources, afforded an intrinsic uncertainty of ∼2 mm for large coaxial detectors and ∼1 mm for planar ones.

  6. Pyroelectric detectors

    NASA Technical Reports Server (NTRS)

    Haller, Eugene E.; Beeman, Jeffrey; Hansen, William L.; Hubbard, G. Scott; Mcmurray, Robert E., Jr.

    1990-01-01

    The multi-agency, long-term Global Change programs, and specifically NASA's Earth Observing system, will require some new and advanced photon detector technology which must be specifically tailored for long-term stability, broad spectral range, cooling constraints, and other parameters. Whereas MCT and GaAs alloy based photovoltaic detectors and detector arrays reach most impressive results to wavelengths as long as 12 microns when cooled to below 70 K, other materials, such as ferroelectrics and pyroelectrics, appear to offer special opportunities beyond 12 microns and above 70 K. These materials have found very broad use in a wide variety of room temperature applications. Little is known about these classes of materials at sub-room temperatures and no photon detector results have been reported. From the limited information available, researchers conclude that the room temperature values of D asterisk greater than or equal to 10(exp 9) cm Hz(exp 1/2)/W may be improved by one to two orders of magnitude upon cooling to temperatures around 70 K. Improvements of up to one order of magnitude appear feasible for temperatures achievable by passive cooling. The flat detector response over a wavelength range reaching from the visible to beyond 50 microns, which is an intrinsic advantage of bolometric devices, makes for easy calibration. The fact that these materials have been developed for reduced temperature applications makes ferro- and pyroelectric materials most attractive candidates for serious exploration.

  7. A Study of Solar Neutrinos Using the Super-Kamiokande Detector

    NASA Astrophysics Data System (ADS)

    Conner, Zoa

    The first solar neutrino flux results from the Super-Kamiokande detector are described. This independent analysis is based on a data set from June 1996 through February 1997. A total neutrino flux of 2.61 ± 0.12 (stat) ±0.13 (syst) ×106/ [ν over cm2s] is implied from the data above a 7 MeV energy threshold. When the measurement is compared with the most recent Standard Solar Model flux prediction (BP95), the ratio of data/SSM is 0.394 ± 0.018 (stat) ± 0.019 (syst). The measured fluxes during day and night yield a fractional difference of +0.019 ± 0.046 (stat). Interpretations are given in the context of vacuum and MSW enhanced neutrino flavor oscillations.

  8. A study of extraterrestrial antineutrino sources with the KamLAND detector

    SciTech Connect

    The KamLAND Collaboration; Gando, A.; Gando, Y.; Ichimura, K.; Ikeda, H.; Inoue, K.; Kibe, Y.; Kishimoto, Y.; Koga, M.; Minekawa, Y.; Mitsui, T.; Morikawa, T.; Nagai, N.; Nakajima, K.; Nakamura, K.; Narita, K.; Shimizu, I.; Shimizu, Y.; Shirai, J.; Suekane, F.; Suzuki, A.; Takahashi, H.; Takahashi, N.; Takemoto, Y.; Tamae, K.; Watanabe, H.; Xu, B. D.; Yabumoto, H.; Yoshida, H.; Yoshida, S.; Enomoto, S.; Kozlov, A.; Murayama, H.; Grant, C.; Keefer, G.; Piepke, A.; Banks, T. I.; Bloxham, T.; Detwiler, J. A.; Freedman, S. J.; Fujikawa, B. K.; Han, K.; Kadel, R.; O'Donnell, T.; Steiner, H. M.; Dwyer, D. A.; McKeown, R. D.; Zhang, C.; Berger, B. E.; Lane, C. E.; Maricic, J.; Miletic, T.; Batygov, M.; Learned, J. G.; Matsuno, S.; Sakai, M.; Horton-Smith, G. A.; Downum, K. E.; Gratta, G.; Efremenko, Y.; Kamyshkov, Y.; Perevozchikov, O.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Heeger, K. M.; Decowski, M. P.

    2011-05-18

    We present the results of a search for extraterrestrial electron antineutrinos ({bar {nu}}{sub e}'s) in the energy range 8.3 MeV < E{sub {bar {nu}}}{sub e} < 30.8 MeV using the KamLAND detector. In an exposure of 4.53 kton-year, we identify 25 candidate events. All of the candidate events can be attributed to background, most importantly neutral current atmospheric neutrino interactions, setting an upper limit on the probability of {sup 8}B solar {nu}{sub e}'s converting into {bar {nu}}{sub e}'s at 5.3 x 10{sup -5} (90% C.L.). The present data also allows us to set more stringent limits on the diffuse supernova neutrino flux and on the annihilation rates for light dark matter particles.

  9. Experimental study of double-{beta} decay modes using a CdZnTe detector array

    SciTech Connect

    Dawson, J. V.; Goessling, C.; Koettig, T.; Muenstermann, D.; Rajek, S.; Schulz, O.; Janutta, B.; Zuber, K.; Junker, M.; Reeve, C.; Wilson, J. R.

    2009-08-15

    An array of sixteen 1 cm{sup 3} CdZnTe semiconductor detectors was operated at the Gran Sasso Underground Laboratory (LNGS) to further investigate the feasibility of double-{beta} decay searches with such devices. As one of the double-{beta} decay experiments with the highest granularity the 4x4 array accumulated an overall exposure of 18 kg days. The setup and performance of the array is described. Half-life limits for various double-{beta} decay modes of Cd, Zn, and Te isotopes are obtained. No signal has been found, but several limits beyond 10{sup 20} years have been performed. They are an order of magnitude better than those obtained with this technology before and comparable to most other experimental approaches for the isotopes under investigation. An improved limit for the {beta}{sup +}/EC decay of {sup 120}Te is given.

  10. A comparative study of heavily irradiated silicon and non irradiated SI LEC GaAs detectors

    SciTech Connect

    Biggeri, U.; Borchi, E.; Bruzzi, M.

    1998-06-01

    Silicon p{sup +}n junctions irradiated with neutron and proton fluences in the range 5 {times} 10{sup 11}--4 {times} 10{sup 15} cm{sup {minus}2} and non-irradiated Semi Insulating (SI) LEC GaAs Schottky barriers have been analyzed. In silicon the concentration N{sub t} of the main radiation-induced deep traps (Et {approx} 0.44--0.54 eV) is found to increase as N{sub t} {alpha} f achieving values up to 5 {times} 10{sup 15} cm{sup {minus}3} and a mobility saturation at 100 cm{sup 2}/Vs has been observed at the highest fluences. A quantitative comparison between heavily irradiated silicon and non-irradiated GaAs evidenced similar charge collection efficiencies, a quasi-intrinsic bulk and similar concentrations of deep defects. On this basis, a unique model, correlating the lattice disorder and the detector performance, is suggested.

  11. Study of spatial resolution of proton computed tomography using a silicon strip detector

    NASA Astrophysics Data System (ADS)

    Saraya, Y.; Izumikawa, T.; Goto, J.; Kawasaki, T.; Kimura, T.

    2014-01-01

    Proton computed tomography (CT) is an imaging technique using a high-energy proton beam penetrating the human body and shows promise for improving the quality of cancer therapy with high-energy particle beams because more accurate electron density distribution measurements can be achieved with proton CT. The deterioration of the spatial resolution owing to multiple Coulomb scattering is, however, a crucial issue. The control of the radiation dose and the long exposure time are also problems to be solved. We have developed a prototype system for proton CT with a silicon strip detector and performed a beam test for imaging. The distribution of the electron density has been measured precisely. We also demonstrated an improvement in spatial resolution by reconstructing the proton trajectory. A spatial resolution of 0.45 mm is achieved for a 25-mm-thick polyethylene object. This will be a useful result for upgrading proton CT application for practical use.

  12. Diode-based transmission detector for IMRT delivery monitoring: a validation study.

    PubMed

    Li, Taoran; Wu, Q Jackie; Matzen, Thomas; Yin, Fang-Fang; O'Daniel, Jennifer C

    2016-01-01

    The purpose of this work was to evaluate the potential of a new transmission detector for real-time quality assurance of dynamic-MLC-based radiotherapy. The accuracy of detecting dose variation and static/dynamic MLC position deviations was measured, as well as the impact of the device on the radiation field (surface dose, transmission). Measured dose variations agreed with the known variations within 0.3%. The measurement of static and dynamic MLC position deviations matched the known deviations with high accuracy (0.7-1.2 mm). The absorption of the device was minimal (~ 1%). The increased surface dose was small (1%-9%) but, when added to existing collimator scatter effects could become significant at large field sizes (≥ 30 × 30 cm2). Overall the accuracy and speed of the device show good potential for real-time quality assurance. PMID:27685115

  13. Efficiency and rate capability studies of the time-of-flight detector for isochronous mass measurements of stored short-lived nuclei with the FRS-ESR facility

    NASA Astrophysics Data System (ADS)

    Kuzminchuk-Feuerstein, Natalia; Fabian, Benjamin; Diwisch, Marcel; Plaß, Wolfgang R.; Geissel, Hans; Ayet San Andrés, Samuel; Dickel, Timo; Knöbel, Ronja; Scheidenberger, Christoph; Sun, Baohua; Weick, Helmut

    2016-06-01

    A time-of-flight (TOF) detector is used for Isochronous Mass Spectrometry (IMS) with the projectile fragment separator FRS and the heavy-ion storage ring ESR. Exotic nuclei are spatially separated in flight with the FRS at about 70% of the speed of light and are injected into the ESR. The revolution times of the stored ions circulating in the ESR are measured with a thin transmission foil detector. When the ions penetrate the thin detector foil, secondary electrons (SEs) are emitted from the surface and provide the timing information in combination with microchannel plate (MCP) detectors. The isochronous transport of the SEs is performed by perpendicular superimposed electric and magnetic fields. The detection efficiency and the rate capability of the TOF detector have been studied in simulations and experiments. As a result the performance of the TOF detector has been improved substantially: (i) The SE collection efficiency was doubled by use of an optimized set of electric and magnetic field values; now SEs from almost the full area of the foil are transmitted to the MCP detectors. (ii) The rate capability of the TOF detector was improved by a factor of four by the use of MCPs with 5 μm pore size. (iii) With these MCPs and a carbon foil with a reduced thickness of 10 μg/cm2 the number of recorded revolutions in the ESR has been increased by nearly a factor of 10. The number of recorded revolutions determine the precision of the IMS experiments. Heavy-ion measurements were performed with neon ions at 322 MeV/u and uranium fission fragments at about 370 MeV/u. In addition, measurements with an alpha source were performed in the laboratory with a duplicate of the TOF detector.

  14. A Study on Determination of an Optimized Detector for Single Photon Emission Computed Tomography.

    PubMed

    Khoshakhlagh, Mohammad; Islamian, Jalil Pirayesh; Abedi, Mohammad; Mahmoudian, Babak; Mardanshahi, Ali Reza

    2016-01-01

    The detector is a critical component of the single photon emission computed tomography (SPECT) imaging system for giving accurate information from the exact pattern of radionuclide distribution in the target organ. The SIMIND Monte Carlo program was utilized for the simulation of a Siemen's dual head variable angle SPECT imaging system with a low energy high resolution (LEHR) collimator. The Planar and SPECT scans for a (99m)Tc point source and a Jaszczak Phantom with the both experiment and simulated systems were prepared and after verification and validation of the simulated system, the similar scans of the phantoms were compared (from the point of view of the images' quality), namely, the simulated system with the detectors including bismuth germanate (BGO), yttrium aluminum garnet (YAG:Ce), Cerium-doped yttrium aluminum garnet (YAG:Ce), yttrium aluminum perovslite (YAP:Ce), lutetium aluminum garnet (LuAG:Ce), cerium activated lanthanum bromide (LaBr3), cadmium zinc telluride (CZT), and sodium iodide activated with thallium [NaI(Tl)]. The parameters of full width at half maximum (FWHM), energy and special resolution, sensitivity, and also the comparison of images' quality by the structural similarity (SSIM) algorithm with the Zhou Wang and Rouse/Hemami methods were analyzed. FWHMs for the crystals were calculated at 13.895, 14.321, 14.310, 14.322, 14.184, and 14.312 keV and the related energy resolutions obtained 9.854, 10.229, 10.221, 10.230, 10.131, and 10.223 %, respectively. Finally, SSIM indexes for comparison of the phantom images were calculated at 0.22172, 0.16326, 0.18135, 0.17301, 0.18412, and 0.20433 as compared to NaI(Tl). The results showed that BGO and LuAG: Ce crystals have high sensitivity and resolution, and better image quality as compared to other scintillation crystals. PMID:26912973

  15. A Study on Determination of an Optimized Detector for Single Photon Emission Computed Tomography

    PubMed Central

    Khoshakhlagh, Mohammad; Islamian, Jalil Pirayesh; Abedi, Mohammad; Mahmoudian, Babak; Mardanshahi, Ali Reza

    2016-01-01

    The detector is a critical component of the single photon emission computed tomography (SPECT) imaging system for giving accurate information from the exact pattern of radionuclide distribution in the target organ. The SIMIND Monte Carlo program was utilized for the simulation of a Siemen's dual head variable angle SPECT imaging system with a low energy high resolution (LEHR) collimator. The Planar and SPECT scans for a 99mTc point source and a Jaszczak Phantom with the both experiment and simulated systems were prepared and after verification and validation of the simulated system, the similar scans of the phantoms were compared (from the point of view of the images’ quality), namely, the simulated system with the detectors including bismuth germanate (BGO), yttrium aluminum garnet (YAG:Ce), Cerium-doped yttrium aluminum garnet (YAG:Ce), yttrium aluminum perovslite (YAP:Ce), lutetium aluminum garnet (LuAG:Ce), cerium activated lanthanum bromide (LaBr3), cadmium zinc telluride (CZT), and sodium iodide activated with thallium [NaI(Tl)]. The parameters of full width at half maximum (FWHM), energy and special resolution, sensitivity, and also the comparison of images’ quality by the structural similarity (SSIM) algorithm with the Zhou Wang and Rouse/Hemami methods were analyzed. FWHMs for the crystals were calculated at 13.895, 14.321, 14.310, 14.322, 14.184, and 14.312 keV and the related energy resolutions obtained 9.854, 10.229, 10.221, 10.230, 10.131, and 10.223 %, respectively. Finally, SSIM indexes for comparison of the phantom images were calculated at 0.22172, 0.16326, 0.18135, 0.17301, 0.18412, and 0.20433 as compared to NaI(Tl). The results showed that BGO and LuAG: Ce crystals have high sensitivity and resolution, and better image quality as compared to other scintillation crystals. PMID:26912973

  16. Trapezoidal-shaped detector to reduce edge effects in small gamma camera

    NASA Astrophysics Data System (ADS)

    Chung, Yong Hyun; Hwang, Ji Yeon; Baek, Cheol-Ha; An, Su Jung; Kim, Hyun-Il; Kim, Kwang Hyun

    2011-08-01

    In recent years, there has been a growing interest in compact and high resolution small gamma cameras for the early detection of breast cancer and thyroid diseases. We proposed a new detector consisting of a trapezoidal-shaped crystal and a position-sensitive photomultiplier tube (PSPMT) to reduce the edge effect. In this study, the imaging performance of the proposed detector was evaluated by DETECT2000 simulation. Trapezoidal-shaped NaI(Tl) and CsI(Tl) crystals were modeled and the 2-dimensional event positions were calculated using Anger-logic. 99mTc (140 keV) and 131I (364 keV) gamma rays were generated on evenly spaced points with 3.0 mm spacing in the X-Y plane starting 1.0 mm away from the corner surface and 10,000 gamma events were simulated at each location. The simulated results demonstrated that all the 99mTc and 131I point sources were clearly identified in the NaI(Tl) crystal. CsI(Tl) crystal could image 131I sources without edge effect but did not distinguish 99mTc points at the periphery region due to low light yield. In conclusion, our new detector with an enlarged FOV without increasing crystal size could be a useful tool in breast as well as thyroid imaging.

  17. PHASE DETECTOR

    DOEpatents

    Kippenhan, D.O.

    1959-09-01

    A phase detector circuit is described for use at very high frequencies of the order of 50 megacycles. The detector circuit includes a pair of rectifiers inverted relative to each other. One voltage to be compared is applied to the two rectifiers in phase opposition and the other voltage to be compared is commonly applied to the two rectifiers. The two result:ng d-c voltages derived from the rectifiers are combined in phase opposition to produce a single d-c voltage having amplitude and polarity characteristics dependent upon the phase relation between the signals to be compared. Principal novelty resides in the employment of a half-wave transmission line to derive the phase opposing signals from the first voltage to be compared for application to the two rectifiers in place of the transformer commonly utilized for such purpose in phase detector circuits for operation at lower frequency.

  18. Study of extensive air showers and primary energy spectra by MAKET-ANI detector on mountain Aragats

    NASA Astrophysics Data System (ADS)

    Chilingarian, A.; Gharagyozyan, G.; Ghazaryan, S.; Hovsepyan, G.; Mamidjanyan, E.; Melkumyan, L.; Romakhin, V.; Vardanyan, A.; Sokhoyan, S.

    2007-09-01

    Small and middle size surface detectors measuring extensive air showers (EAS) initiated by primary cosmic rays (PCR) incident on terrestrial atmosphere have been in operation for the last 50 years. Their main goal is to explore the "knee" in all particle spectrum to solve the problem of cosmic ray (CR) origin and acceleration. The recent achievements of atmospheric Cherenkov telescopes and X-ray space laboratories, establishing the supernova remnants (SNRs) as a source of hadronic cosmic rays, pose stringent conditions on the quality of EAS evidence. After establishing the existence of the "knee" itself, the most pronounced result from EAS studies is the rigidity dependent shift of the knee position to the highest energies. This feature was first observed by separation of the primary flux in different mass groups in MAKET-ANI, EAS-TOP and KASCADE experiments. The MAKET-ANI detector is placed on Mt. Aragats (Armenia) at 3200 m above the sea level (40°25'N, 44°15'E). More than 1.3 × 10 6 showers with size greater than 10 5 particles were registered in 1997-2004. The detector effectively collected the cores of EAS, initiated by primaries with energies of 10 14-10 17 eV. After proving that the quality of the EAS size and shape reconstruction was reasonably high, we present the lateral distribution function (LDF) for distances from 10 to 120 m from EAS core and EAS size spectra in 5 zenith angle intervals. We use CORSIKA simulations to present the energy spectra. The results from the MAKET-ANI experiment on the energy spectra of the "light"(p + He) and "heavy" (O + Si + Fe) nuclear groups are compared to the spectra obtained by balloon experiments and to other available spectra.

  19. Theoretical feasibility study on neutron spectrometry with the polyallyldiglycol carbonate (PADC) solid-state nuclear track detector

    NASA Astrophysics Data System (ADS)

    Nikezic, D.; Yu, K. N.

    2015-01-01

    Neutron spectrometry with the polyallyldiglycol carbonate (PADC) film detector was analyzed in detail. The computer codes TRACK_TEST and TRACK_VISION, which were originally developed for studies on alpha-particle tracks, were modified to compute parameters of etched proton tracks developed in the PADC film detector and to simulate their appearance under an optical microscope in the transmission mode. It was shown that protons with same energy and recoil angle could produce different etched tracks with various size and shape, depending on the point of their creation. As such, it was necessary to employ multiple etching, and to measure the removed layer thickness and to record the track appearance after each etching step. A new variable, namely, the effective removed layer heff, was introduced as the difference between the total removed layer and the depth where the proton was created in the detector. A program modified from the TRACK_VISION code was used to plot the appearance of a number of representative etched proton tracks. For proton energies larger than 2 MeV, the V function for protons in PADC was found to be almost constant, so the simple formulas for major and minor axes of proton track openings could be used to determine the proton energy, recoiled angle as well as the energy of the neutron which caused the proton recoil. For lower proton energies, a databank of various proton tracks showing the track opening appearances and the track profiles should be created for comparison to facilitate the determination of the proton energy.

  20. Hydrogen detector

    DOEpatents

    Kanegae, Naomichi; Ikemoto, Ichiro

    1980-01-01

    A hydrogen detector of the type in which the interior of the detector is partitioned by a metal membrane into a fluid section and a vacuum section. Two units of the metal membrane are provided and vacuum pipes are provided independently in connection to the respective units of the metal membrane. One of the vacuum pipes is connected to a vacuum gauge for static equilibrium operation while the other vacuum pipe is connected to an ion pump or a set of an ion pump and a vacuum gauge both designed for dynamic equilibrium operation.

  1. Microwave detector

    DOEpatents

    Meldner, Heiner W.; Cusson, Ronald Y.; Johnson, Ray M.

    1986-01-01

    A microwave detector (10) is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite (26, 28) produces a magnetization field flux that links a B-dot loop (16, 20). The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means (18, 22) are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

  2. Microwave detector

    DOEpatents

    Meldner, H.W.; Cusson, R.Y.; Johnson, R.M.

    1985-02-08

    A microwave detector is provided for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations. A biased ferrite produces a magnetization field flux that links a B-dot loop. The magnetic field of the microwave pulse participates in the formation of the magnetization field flux. High-frequency insensitive means are provided for measuring electric voltage or current induced in the B-dot loop. The recorded output of the detector is proportional to the time derivative of the square of the envelope shape of the microwave pulse.

  3. Silicon Detectors

    NASA Astrophysics Data System (ADS)

    Sadrozinski, Hartmut

    2014-03-01

    The use of silicon detectors has experienced an exponential growth in accelerator and space based experiments, similar to trends in the semiconductor industry as a whole, usually paraphrased as ``Moore's Law.'' Some of the essentials for this phenomenon will be presented, together with examples of the exciting science results which it enabled. With the establishment of a ``semiconductor culture'' in universities and laboratories around the world, an increased understanding of the sensors results in thinner, faster, more radiation-resistant detectors, spawning an amazing wealth of new technologies and applications, which will be the main subject of the presentation.

  4. Microwave detector

    SciTech Connect

    Meldner, H.W.; Cusson, R.Y.; Johnson, R.M.

    1986-12-02

    A detector is described for measuring the envelope shape of a microwave pulse comprised of high-frequency oscillations, the detector comprising: a B-dot loop linking the magnetic field of the microwave pulse; a biased ferrite, that produces a magnetization field flux that links the B-dot loop. The ferrite is positioned within the B-dot loop so that the magnetic field of the microwave pulse interacts with the ferrite and thereby participates in the formation of the magnetization field flux; and high-frequency insensitive means for measuring electric voltage or current induced in the B-dot loop.

  5. Measuring the Free Fall of Antihydrogen with Emulsion Detectors

    NASA Astrophysics Data System (ADS)

    Pistillo, C.

    2014-06-01

    The AEgIS experiment at CERN is designed to perform the first direct measurement of gravitational interaction between antimatter and matter by detecting the fall of a horizontally accelerated cold antihydrogen beam in the Earth's gravitational field. The spatial resolution of the position sensitive detector is a key issue for the success of the experiment. For this reason, the employment of emulsion film detectors is being considered and an intense R&D is being conducted to define the use of this technology in the AEgIS apparatus. We present the results of test beams conducted in 2012, when emulsion film detectors were directly exposed to a ˜ 100 keV antiproton beam and annihilation vertices successfully reconstructed with a few micrometers resolution. The prospects for the realization of the final detector are also presented.

  6. Application of Mythen detector: In-situ XRD study on the thermal expansion behavior of metal indium

    NASA Astrophysics Data System (ADS)

    Du, Rong; Chen, ZhongJun; Cai, Quan; Fu, JianLong; Gong, Yu; Wu, ZhongHua

    2016-07-01

    A Mythen detector has been equipped at the beamline 4B9A of Beijing Synchrotron Radiation Facility (BSRF), which is expected to enable BSRF to perform time-resolved measurement of X-ray diffraction (XRD) full-profiles. In this paper, the thermal expansion behavior of metal indium has been studied by using the in-situ XRD technique with the Mythen detector. The indium was heated from 303 to 433 K with a heating rate of 2 K/min. The in-situ XRD full-profiles were collected with a rate of one profile per 10 seconds. Rietveld refinement was used to extract the structural parameters. The results demonstrate that these collected quasi-real-time XRD profiles can be well used for structural analysis. The metal indium was found to have a nonlinear thermal expansion behavior from room temperature to the melting point (429.65 K). The a-axis of the tetragonal unit cell expands with a biquadratic dependency on temperature, while the c-axis contracts with a cubic dependency on temperature. By the time-resolved XRD measurements, it was observed that the [200] preferred orientation can maintain to about 403.15 K. While (110) is the last and detectable crystal plane just before melting of the polycrystalline indium foil. This study is not only beneficial to the application of metal indium, but also exhibits the capacity of in-situ time-resolved XRD measurements at the X-ray diffraction station of BSRF.

  7. S-NPP VIIRS DNB Dark Offset and Detector Dark Current Trending Study

    NASA Astrophysics Data System (ADS)

    Sun, Z.; Chen, W.; DeLuccia, F.; Moy, G.

    2015-12-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) Day-Night Band (DNB) is a panchromatic band in the VisNIR spectral range from 0.5 to 0.9 μm with a dynamic range from 3x10-9 to about 0.02 W cm-2 sr-1. DNB achieves this large dynamic range by having three gain stages: low gain (LGS), mid gain (MGS), and high gain (HGS). HGS is the average of two redundant detector arrays, HGA and HGB. The HGS offset determination is critically important to improve the imagery capability and calibration accuracy and stability at novel low radiances. Currently, the dark offset is determined on a monthly basis by observing new moon data in the dark regions in the Pacific Ocean. The data is mainly comprised of detector dark current, electronic/clock offsets, artificial illumination sources, and nighttime airglow contamination. The first two are instrument phenomena/characterizations and the last two are scene contaminations.In this presentation, we discuss the long-term growth in offset with short-term fluctuations we have captured since the beginning of the mission. We associate the long-term growth with dark current increase. We show that the offset rate of change over time is proportional to the number of Charge Coupled Device (CCD) elements aggregated to comprise a DNB pixel. We compare offset growth rate from new moon data in the dark ocean and that from calibration sector data at the same time; which contain very limited scene contaminations. We associate the short-term variability in offset growth with airglow effects that survive the filtering process used to derive the offsets from dark ocean data. These spurious offset fluctuations are removed from the offset LUTs via long time scale smoothing of the offsets. The remaining persistent time average contribution due to airglow can be estimated by comparison of the pitch maneuver propagated offsets determined from deep space scans early in the mission and the offsets determined from the dark regions in the Pacific Ocean.

  8. Development of the High-resolution FUV Detector for the BepiColombo Mission

    NASA Astrophysics Data System (ADS)

    Murakami, Go; Yoshioka, Kazuo; Yoshikawa, Ichiro

    The PHEBUS (Probing of Hermean Exosphere By Ultraviolet Spectroscopy) instrument on Mercury Planetary Orbiter in the BepiColombo mission is a dual FUV-EUV spectrometer (EUV: 55-155 nm, FUV: 145-315 nm). We are now developing the compact detector system sensitive to FUV airglow emissions of the Mercury. The FUV detector is required to have high spatial resolution (512×512 pixels) so that the wavelength resolution of the PHEBUS instrument should be 2 nm at the FUV range. The FUV detector consists of a Cs2Te photocathode, microchannel plates (MCPs), and a resistive anode encoder. In a position-sensitive system with a resistive anode encoder, the spatial resolution is determined by the signal-to-noise ratios at the anode terminals. Therefore, a high and stable electron gain of MCPs allows the position determination of each photoelectron event with high spatial resolution. We studied a method for achieving a high and stable electron gain. We fabricated a test model of the FUV detector incorporating a clamped pair of MCPs (V-stack) followed by a gap and a clamped triplet of MCPs (Z-stack) in cascade. We investigated the effect of the negative inter-stack potential on the PHD and the spatial resolution by means of calculation and experiments. As a result, the negative inter-stack potential made the electron gain more stable and the spatial resolution higher by ˜14%. In this paper we report the specific performance of the test model of the FUV detector.

  9. Study of scintillation, fluorescence and scattering in mineral oil for the MiniBooNE neutrino detector

    SciTech Connect

    Brown, Bruce C.; Brice, Stephen; Hawker, Eric; Maza, Shannon; Meyer, Hans-Otto; Pla-Dalmau, Anna; Tayloe, Rex; Tanaka, Hirohisa A.; Toptygin, Dmitri; /Fermilab /Western Illinois U. /Indiana U. /Princeton U. /Johns Hopkins U.

    2004-11-01

    The MiniBooNE neutrino detector at Fermilab (FNAL) is filled with 250,000 gallons of pure mineral oil. The principal signal for MiniBooNE is light observed in a prompt Cherenkov cone. Scattering and fluorescence modify our detection of this light. Scintillation is also created by ionization in the oil. Studies of fluorescence of this oil have been carried out over a wide spectrum of exciting light and time resolved fluorescence with a narrower range of excitation. Polarized scattering measurements have been carried out at longer wavelengths. Time resolved and spectrally resolved scintillation has been studied with a 200 MeV Proton beam at the Indiana University Cyclotron Facility. Results of these studies will be reported.

  10. Vertex detectors

    SciTech Connect

    Lueth, V.

    1992-07-01

    The purpose of a vertex detector is to measure position and angles of charged particle tracks to sufficient precision so as to be able to separate tracks originating from decay vertices from those produced at the interaction vertex. Such measurements are interesting because they permit the detection of weakly decaying particles with lifetimes down to 10{sup {minus}13} s, among them the {tau} lepton and charm and beauty hadrons. These two lectures are intended to introduce the reader to the different techniques for the detection of secondary vertices that have been developed over the past decades. The first lecture includes a brief introduction to the methods used to detect secondary vertices and to estimate particle lifetimes. It describes the traditional technologies, based on photographic recording in emulsions and on film of bubble chambers, and introduces fast electronic registration of signals derived from scintillating fibers, drift chambers and gaseous micro-strip chambers. The second lecture is devoted to solid state detectors. It begins with a brief introduction into semiconductor devices, and then describes the application of large arrays of strip and pixel diodes for charged particle tracking. These lectures can only serve as an introduction the topic of vertex detectors. Time and space do not allow for an in-depth coverage of many of the interesting aspects of vertex detector design and operation.

  11. DETECTORS AND EXPERIMENTAL METHODS: Study of the characteristics of a scintillation array and single pixels for nuclear medicine imaging applications

    NASA Astrophysics Data System (ADS)

    Zhu, Jie; Ma, Hong-Guang; Ma, Wen-Yan; Zeng, Hui; Wang, Zhao-Min; Xu, Zi-Zong

    2009-04-01

    By using a pixelized Nal(Tl) crystal array coupled to a R2486 PSPMT, the characteristics of the array and of a single pixel, such as the light output, energy resolution, peak-to-valley ratio (P/V) and imaging performance of the detector were studied. The pixel size of the NaI(TI) scintillation pixel array is 2 mm×2 mm×5 mm. There are in total 484 pixels in a 22 × 22 matrix. In the pixel spectrum an average peak-to-valley ratio (P/V) of 16 was obtained. In the image of all the pixels, good values for the Peak-to-Valley ratios could be achieved, namely a mean of 17, a maximum of 45 and the average peak FWHM (the average value of intrinsic spatial resolution) of 2.3 mm. However, the PSPMT non-uniform response and the scintillation pixels array inhomogeneities degrade the imaging performance of the detector.

  12. Optimized acquisition time for x-ray fluorescence imaging of gold nanoparticles: a preliminary study using photon counting detector

    NASA Astrophysics Data System (ADS)

    Ren, Liqiang; Wu, Di; Li, Yuhua; Chen, Wei R.; Zheng, Bin; Liu, Hong

    2016-03-01

    X-ray fluorescence (XRF) is a promising spectroscopic technique to characterize imaging contrast agents with high atomic numbers (Z) such as gold nanoparticles (GNPs) inside small objects. Its utilization for biomedical applications, however, is greatly limited to experimental research due to longer data acquisition time. The objectives of this study are to apply a photon counting detector array for XRF imaging and to determine an optimized XRF data acquisition time, at which the acquired XRF image is of acceptable quality to allow the maximum level of radiation dose reduction. A prototype laboratory XRF imaging configuration consisting of a pencil-beam X-ray and a photon counting detector array (1 × 64 pixels) is employed to acquire the XRF image through exciting the prepared GNP/water solutions. In order to analyze the signal to noise ratio (SNR) improvement versus the increased exposure time, all the XRF photons within the energy range of 63 - 76KeV that include two Kα gold fluorescence peaks are collected for 1s, 2s, 3s, and so on all the way up to 200s. The optimized XRF data acquisition time for imaging different GNP solutions is determined as the moment when the acquired XRF image just reaches a quality with a SNR of 20dB which corresponds to an acceptable image quality.

  13. A Study of Particle Production in Proton Induced Collisions Using the MIPP Detector at Fermilab

    SciTech Connect

    Mahajan, Sonam

    2015-01-01

    The Main Injector Particle Production (MIPP) experiment is a fixed target hadron production experiment at Fermilab. MIPP is a high acceptance spectrometer which provides excellent charged particle identification using Time Projection Chamber (TPC), Time of Flight (ToF), multicell Cherenkov (Ckov), ring imaging Cherenkov (RICH) detectors, and Calorimeter for neutrons. The MIPP experiment is designed to measure particle production in interactions of 120 GeV/c primary protons from the Main Injector and secondary beams of $\\pi^{\\pm}, \\rm{K}^{\\pm}$, p and $\\bar{\\rm{p}}$ from 5 to 90 GeV/c on nuclear targets which include H, Be, C, Bi and U, and a dedicated run with the NuMI target. The goal of the experiment is to measure hadron production cross sections or yields using these beams and targets. These hadronic interaction data can have a direct impact on the detailed understanding of the neutrino fluxes of several accelerator-based neutrino experiments like MINOS, MINER$\

  14. First-principles studies of Ce and Eu doped inorganic scintillator gamma ray detectors

    NASA Astrophysics Data System (ADS)

    Canning, Andrew; Chaudhry, Anurag; Boutchko, Rostyslav; Derenzo, Stephen

    2011-03-01

    We have performed DFT based band structure calculations for new Ce and Eu doped wide band gap inorganic materials to determine their potential as candidates for gamma ray scintillator detectors. These calculations are based on determining the 4f ground state level of the Ce and Eu relative to the valence band of the host as well as the position of the Ce and Eu 5d excited state relative to the conduction band of the host. Host hole and electron traps as well as STEs (self trapped excitons) can also limit the transfer of energy from the host to the Ce or Eu site and therefore limit the light output. We also present calculations for host hole traps and STEs to compare the energies to the Ce and Eu excited states. The work was supported by the U.S. Department of Homeland Security and carried out at the Lawrence Berkeley National Laboratory under U.S. Department of Energy Contract No. DE-AC02- 05CH11231.

  15. Hadron reactions study with the CMD-3 detector in e+e‑ collisions

    NASA Astrophysics Data System (ADS)

    Solodov, E. P.; Amirkhanov, A. N.; Anisenkov, A. V.; Aulchenko, V. M.; Banzarov, V. S.; Bashtovoy, N. S.; Bondar, A. E.; Bragin, A. V.; Eidelman, S. I.; Epifanov, D. A.; Epshteyn, L. B.; Erofeev, A. L.; Fedotovich, G. V.; Gayazo, S. E.; Grebenuk, A. A.; Gribanov, S. S.; Grigoriev, D. N.; Ignatov, F. V.; Ivanov, V. L.; Karpov, S. V.; Kazanin, V. F.; Korobov, A. A.; Kovalenko, O. A.; Kozyrev, A. N.; Kozyrev, E. A.; Krokovny, P. P.; Kuzmenko, A. E.; Kuzmin, A. S.; Logashenko, I. B.; Lukin, P. A.; Mikhailov, K. Yu.; Okhapkin, V. S.; Pestov, Yu. N.; Popov, A. S.; Razuvaev, G. P.; Ruban, A. A.; Ryskulov, N. M.; Ryzhenenkov, A. E.; Shebalin, V. E.; Shemyakin, D. N.; Shwartz, B. A.; Sibidanov, A. L.; Shatunov, Yu. M.; Titov, V. M.; Talyshev, A. A.; Vorobiov, A. I.; Yudin, Yu. V.

    2016-09-01

    The CMD-3 detector has been taking data since December 2010 at the VEPP-2000 electron-positron collider. The collected data sample corresponds to about 60 inverse picobarn of integrated luminosity in the c.m. energy range from 0.32 GeV to 2.0 GeV. Preliminary results of the analysis of various hadronic cross-sections, in particular, e+e‑→ π+π‑, π+π‑π0, KLKS, K+K‑, ηγ, 3(π+π‑), 2(π+π‑π0), K+K‑π+π‑, K+K‑η, K+K‑π0, ηπ+π‑, ωπ+π‑ and ω → π0e+e‑ are presented. The processes with multi-hadron final states have several intermediate states which have to be taken into account to correctly describe the angular and invariant mass distributions, as well as cross-section energy dependence.

  16. Simulation study comparing high-purity germanium and cadmium zinc telluride detectors for breast imaging.

    PubMed

    Campbell, D L; Peterson, T E

    2014-11-21

    We conducted simulations to compare the potential imaging performance for breast cancer detection with High-Purity Germanium (HPGe) and Cadmium Zinc Telluride (CZT) systems with 1% and 3.8% energy resolution at 140 keV, respectively. Using the Monte Carlo N-Particle (MCNP5) simulation package, we modelled both 5 mm-thick CZT and 10 mm-thick HPGe detectors with the same parallel-hole collimator for the imaging of a breast/torso phantom. Simulated energy spectra were generated, and planar images were created for various energy windows around the 140 keV photopeak. Relative sensitivity and scatter and the torso fractions were calculated along with tumour contrast and signal-to-noise ratios (SNR). Simulations showed that utilizing a ±1.25% energy window with an HPGe system better suppressed torso background and small-angle scattered photons than a comparable CZT system using a -5%/+10% energy window. Both systems provided statistically similar contrast and SNR, with HPGe providing higher relative sensitivity. Lowering the counts of HPGe images to match CZT count density still yielded equivalent contrast between HPGe and CZT. Thus, an HPGe system may provide equivalent breast imaging capability at lower injected radioactivity levels when acquiring for equal imaging time.

  17. Simulation study comparing high-purity germanium and cadmium zinc telluride detectors for breast imaging

    PubMed Central

    Campbell, DL; Peterson, TE

    2014-01-01

    We conducted simulations to compare the potential imaging performance for breast cancer detection with High-Purity Germanium (HPGe) and Cadmium Zinc Telluride (CZT) systems with 1% and 3.8% energy resolution at 140 keV, respectively. Using the Monte Carlo N-Particle (MCNP5) simulation package, we modelled both 5 mm-thick CZT and 10 mm-thick HPGe detectors with the same parallel-hole collimator for the imaging of a breast/torso phantom. Simulated energy spectra were generated, and planar images were created for various energy windows around the 140-keV photopeak. Relative sensitivity and scatter and the torso fractions were calculated along with tumour contrast and signal-to-noise ratios (SNR). Simulations showed that utilizing a ±1.25% energy window with an HPGe system better suppressed torso background and small-angle scattered photons than a comparable CZT system using a −5%/+10% energy window. Both systems provided statistically similar contrast and SNR, with HPGe providing higher relative sensitivity. Lowering the counts of HPGe images to match CZT count density still yielded equivalent contrast between HPGe and CZT. Thus, an HPGe system may provide equivalent breast imaging capability at lower injected radioactivity levels when acquiring for equal imaging time. PMID:25360792

  18. Study of Cosmic Ray Impact on Planck/HFI Low Temperature Detectors

    NASA Astrophysics Data System (ADS)

    Miniussi, A.; Puget, J.-L.; Holmes, W.; Patanchon, G.; Catalano, A.; Giraud-Heraud, Y.; Pajot, F.; Piat, M.; Vibert, L.

    2014-09-01

    Once that the focal plane of the HFI instrument of the Planck mission (launched in May 2009) has reached operational temperature, we have observed the thermal effect of cosmic ray interaction with the Planck satellite, located at Lagrangian point L2. When a particle hits a component of the bolometers (e.g.: thermometer, grid or wafer) composing the focal plane of HFI, a thermal spike (called glitch), due to deposited energy, is observed. Processing these data revealed another effect due to high energy cosmic ray particle showers: High Coincidence Events (HCE), composed of glitches occurring coincidentally in many detectors and with a temperature increase from nK to K after the shower. A flux of about 100 HCE per hour has been calculated. Two types of HCE have been detected: fast and slow. For the first type, the untouched bolometers reach the same temperature as the touched ones in a few seconds which can be explained by a storage of the deposited energy in the stainless steel focal plane. The second type of HCE is not fully understood yet. These effects might be explained by extra conduction from the helium released from cryogenic surfaces, creating a temporary thermal link between the different stages of the HFI.

  19. Calibration Analyses and Efficiency Studies for the Anti Coincidence Detector on the Fermi Gamma Ray Space Telescope

    SciTech Connect

    Kachulis, Chris; /Yale U. /SLAC

    2011-06-22

    The Anti Coincidence Detector (ACD) on the Fermi Gamma Ray Space Telescope provides charged particle rejection for the Large Area Telescope (LAT). We use two calibrations used by the ACD to conduct three studies on the performance of the ACD. We examine the trending of the calibrations to search for damage and find a timescale over which the calibrations can be considered reliable. We also calculated the number of photoelectrons counted by a PMT on the ACD from a normal proton. Third, we calculated the veto efficiencies of the ACD for two different veto settings. The trends of the calibrations exhibited no signs of damage, and indicated timescales of reliability for the calibrations of one to two years. The number of photoelectrons calculated ranged from 5 to 25. Large errors in the effect of the energy spectrum of the charged particles caused these values to have very large errors of around 60 percent. Finally, the veto efficiencies were found to be very high at both veto values, both for charged particles and for the lower energy backsplash spectrum. The Anti Coincidence Detector (ACD) on the Fermi Gamma Ray Space Telescope is a detector system built around the silicon strip tracker on the Large Area Telescope (LAT). The purpose of the ACD is to provide charged particle rejection for the LAT. To do this, the ACD must be calibrated correctly in flight, and must be able to efficiently veto charged particle events while minimizing false vetoes due to 'backsplash' from photons in the calorimeter. There are eleven calibrations used by the ACD. In this paper, we discuss the use of two of these calibrations to preform three studies on the performance of the ACD. The first study examines trending of the calibrations to check for possible hardware degradation. The second study uses the calibrations to explore the efficiency of an on-board hardware veto. The third study uses the calibrations to calculate the number of photoelectrons seen by each PMT when a minimum ionizing

  20. Advanced Space Radiation Detector Technology Development

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.

    2013-01-01

    The advanced space radiation detector development team at NASA Glenn Research Center (GRC) has the goal of developing unique, more compact radiation detectors that provide improved real-time data on space radiation. The team has performed studies of different detector designs using a variety of combinations of solid-state detectors, which allow higher sensitivity to radiation in a smaller package and operate at lower voltage than traditional detectors. Integration of multiple solid-state detectors will result in an improved detector system in comparison to existing state-of-the-art instruments for the detection and monitoring of the space radiation field for deep space and aerospace applications.

  1. Advanced Space Radiation Detector Technology Development

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.

    2013-01-01

    The advanced space radiation detector development team at the NASA Glenn Research Center (GRC) has the goal of developing unique, more compact radiation detectors that provide improved real-time data on space radiation. The team has performed studies of different detector designs using a variety of combinations of solid-state detectors, which allow higher sensitivity to radiation in a smaller package and operate at lower voltage than traditional detectors. Integration of multiple solid-state detectors will result in an improved detector system in comparison to existing state-of-the-art instruments for the detection and monitoring of the space radiation field for deep space and aerospace applications.

  2. Advanced Space Radiation Detector Technology Development

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Wrbanek, Susan Y.; Fralick, Gustave C.

    2013-01-01

    The advanced space radiation detector development team at NASA Glenn Research Center (GRC) has the goal of developing unique, more compact radiation detectors that provide improved real-time data on space radiation. The team has performed studies of different detector designs using a variety of combinations of solid-state detectors, which allow higher sensitivity to radiation in a smaller package and operate at lower voltage than traditional detectors. Integration of multiple solid-state detectors will result in an improved detector system in comparison to existing state-of-the-art (SOA) instruments for the detection and monitoring of the space radiation field for deep space and aerospace applications.

  3. Study of gamma ray response of R404A superheated droplet detector using a two-state model.

    PubMed

    Mondal, P K; Chatterjee, B K

    2013-07-01

    The superheated droplet detector (SDD) is known to be gamma ray insensitive below a threshold temperature which made them excellent candidates for neutron detection in the presence of gamma rays. Above the threshold temperature, the gamma ray detection efficiency increases with increase in temperature. In this work the gamma ray threshold temperature has been studied for SDD using R404A as the active liquid and is compared to the theoretical prediction. The temperature variation of gamma ray detection efficiency and interstate transition kinetics has also been studied using a two-state model. The experiments are performed at the ambient pressure of 1 atm and in the temperature range of 17-32 °C using a 662 keV (1)(37)Cs gamma ray source. PMID:23528644

  4. The studies of Schottky-diode based co-plane detector for surface plasmon resonance sensing

    NASA Astrophysics Data System (ADS)

    Liu, Chien-Sheng; Wen, Tsun-Yu; Wang, Da-Shin; Lin, Chii-Wann

    2010-08-01

    The Surface Plasmon Resonance (SPR) is a label-free, highly sensitive and real time sensing technique and has been extensively applied to biosensing and assay for decades. In a conventional SPR biosensor, a prism is used to create the total reflection in which the evanescent wave can excite the surface plasmon mode at the metal-dielectric interface at certain angle, at which condition the reflectivity of incident TM-polarized vanished as measured by a far-field photodetector. This is the optical detection of surface plasmon resonance. In this research, zinc oxide (ZnO) was used as the dielectric thin-film material above the gold surface on the glass substrate to form a co-plane Schottky diode; this structure is designed to be an alternative way to detect SPR. The strength of plasmonic field is possible to be monitored by measuring the photocurrent under the reverse bias. According to our experimental results, the measured photocurrents with TM-polarized illumination (representing the SPR case), TE-polarized illumination (non-SPR case) and no illumination conditions under DC -1.5V bias are -76.158mA (2.5μA), -76.085mA (3.6μA) and -76.089mA (3.4μA), respectively. Based on the results, we have demonstrated this Schottky diode based co-plane device has the potential to be used as the SPR detector and provides a possible solution for the need of a low-cost, miniaturized, electronically integrated, and portable SPR biosensor in the near future.

  5. The MINDView brain PET detector, feasibility study based on SiPM arrays

    NASA Astrophysics Data System (ADS)

    González, Antonio J.; Majewski, Stan; Sánchez, Filomeno; Aussenhofer, Sebastian; Aguilar, Albert; Conde, Pablo; Hernández, Liczandro; Vidal, Luis F.; Pani, Roberto; Bettiol, Marco; Fabbri, Andrea; Bert, Julien; Visvikis, Dimitris; Jackson, Carl; Murphy, John; O'Neill, Kevin; Benlloch, Jose M.

    2016-05-01

    The Multimodal Imaging of Neurological Disorders (MINDView) project aims to develop a dedicated brain Positron Emission Tomography (PET) scanner with sufficient resolution and sensitivity to visualize neurotransmitter pathways and their disruptions in mental disorders for diagnosis and follow-up treatment. The PET system should be compact and fully compatible with a Magnetic Resonance Imaging (MRI) device in order to allow its operation as a PET brain insert in a hybrid imaging setup with most MRI scanners. The proposed design will enable the currently-installed MRI base to be easily upgraded to PET/MRI systems. The current design for the PET insert consists of a 3-ring configuration with 20 modules per ring and an axial field of view of ~15 cm and a geometrical aperture of ~33 cm in diameter. When coupled to the new head Radio Frequency (RF) coil, the inner usable diameter of the complete PET-RF coil insert is reduced to 26 cm. Two scintillator configurations have been tested, namely a 3-layer staggered array of LYSO with 1.5 mm pixel size, with 35×35 elements (6 mm thickness each) and a black-painted monolithic LYSO block also covering about 50×50 mm2 active area with 20 mm thickness. Laboratory test results associated with the current MINDView PET module concept are presented in terms of key parameters' optimization, such as spatial and energy resolution, sensitivity and Depth of Interaction (DOI) capability. It was possible to resolve all pixel elements from the three scintillator layers with energy resolutions as good as 10%. The monolithic scintillator showed average detector resolutions varying from 3.5 mm in the entrance layer to better than 1.5 mm near the photosensor, with average energy resolutions of about 17%.

  6. Monte Carlo study of the energy and angular dependence of the response of plastic scintillation detectors in photon beams

    SciTech Connect

    Wang, Lilie L. W.; Klein, David; Beddar, A. Sam

    2010-10-15

    Purpose: By using Monte Carlo simulations, the authors investigated the energy and angular dependence of the response of plastic scintillation detectors (PSDs) in photon beams. Methods: Three PSDs were modeled in this study: A plastic scintillator (BC-400) and a scintillating fiber (BCF-12), both attached by a plastic-core optical fiber stem, and a plastic scintillator (BC-400) attached by an air-core optical fiber stem with a silica tube coated with silver. The authors then calculated, with low statistical uncertainty, the energy and angular dependences of the PSDs' responses in a water phantom. For energy dependence, the response of the detectors is calculated as the detector dose per unit water dose. The perturbation caused by the optical fiber stem connected to the PSD to guide the optical light to a photodetector was studied in simulations using different optical fiber materials. Results: For the energy dependence of the PSDs in photon beams, the PSDs with plastic-core fiber have excellent energy independence within about 0.5% at photon energies ranging from 300 keV (monoenergetic) to 18 MV (linac beam). The PSD with an air-core optical fiber with a silica tube also has good energy independence within 1% in the same photon energy range. For the angular dependence, the relative response of all the three modeled PSDs is within 2% for all the angles in a 6 MV photon beam. This is also true in a 300 keV monoenergetic photon beam for PSDs with plastic-core fiber. For the PSD with an air-core fiber with a silica tube in the 300 keV beam, the relative response varies within 1% for most of the angles, except in the case when the fiber stem is pointing right to the radiation source in which case the PSD may over-response by more than 10%. Conclusions: At {+-}1% level, no beam energy correction is necessary for the response of all three PSDs modeled in this study in the photon energy ranges from 200 keV (monoenergetic) to 18 MV (linac beam). The PSD would be even closer

  7. Monte Carlo study of the energy and angular dependence of the response of plastic scintillation detectors in photon beams

    PubMed Central

    Wang, Lilie L. W.; Klein, David; Beddar, A. Sam

    2010-01-01

    Purpose: By using Monte Carlo simulations, the authors investigated the energy and angular dependence of the response of plastic scintillation detectors (PSDs) in photon beams. Methods: Three PSDs were modeled in this study: A plastic scintillator (BC-400) and a scintillating fiber (BCF-12), both attached by a plastic-core optical fiber stem, and a plastic scintillator (BC-400) attached by an air-core optical fiber stem with a silica tube coated with silver. The authors then calculated, with low statistical uncertainty, the energy and angular dependences of the PSDs’ responses in a water phantom. For energy dependence, the response of the detectors is calculated as the detector dose per unit water dose. The perturbation caused by the optical fiber stem connected to the PSD to guide the optical light to a photodetector was studied in simulations using different optical fiber materials. Results: For the energy dependence of the PSDs in photon beams, the PSDs with plastic-core fiber have excellent energy independence within about 0.5% at photon energies ranging from 300 keV (monoenergetic) to 18 MV (linac beam). The PSD with an air-core optical fiber with a silica tube also has good energy independence within 1% in the same photon energy range. For the angular dependence, the relative response of all the three modeled PSDs is within 2% for all the angles in a 6 MV photon beam. This is also true in a 300 keV monoenergetic photon beam for PSDs with plastic-core fiber. For the PSD with an air-core fiber with a silica tube in the 300 keV beam, the relative response varies within 1% for most of the angles, except in the case when the fiber stem is pointing right to the radiation source in which case the PSD may over-response by more than 10%. Conclusions: At ±1% level, no beam energy correction is necessary for the response of all three PSDs modeled in this study in the photon energy ranges from 200 keV (monoenergetic) to 18 MV (linac beam). The PSD would be even closer

  8. Neutron detector

    DOEpatents

    Stephan, Andrew C.; Jardret; Vincent D.

    2011-04-05

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  9. Neutron detector

    SciTech Connect

    Stephan, Andrew C; Jardret, Vincent D

    2009-04-07

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  10. Angle detector

    NASA Technical Reports Server (NTRS)

    Parra, G. T. (Inventor)

    1978-01-01

    An angle detector for determining a transducer's angular disposition to a capacitive pickup element is described. The transducer comprises a pendulum mounted inductive element moving past the capacitive pickup element. The capacitive pickup element divides the inductive element into two parts L sub 1 and L sub 2 which form the arms of one side of an a-c bridge. Two networks R sub 1 and R sub 2 having a plurality of binary weighted resistors and an equal number of digitally controlled switches for removing resistors from the networks form the arms of the other side of the a-c bridge. A binary counter, controlled by a phase detector, balances the bridge by adjusting the resistance of R sub 1 and R sub 2. The binary output of the counter is representative of the angle.

  11. Flame Detector

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Scientific Instruments, Inc. has now developed a second generation, commercially available instrument to detect flames in hazardous environments, typically refineries, chemical plants and offshore drilling platforms. The Model 74000 detector incorporates a sensing circuit that detects UV radiation in a 100 degree conical field of view extending as far as 250 feet from the instrument. It operates in a bandwidth that makes it virtually 'blind' to solar radiation while affording extremely high sensitivity to ultraviolet flame detection. A 'windowing' technique accurately discriminates between background UV radiation and ultraviolet emitted from an actual flame, hence the user is assured of no false alarms. Model 7410CP is a combination controller and annunciator panel designed to monitor and control as many as 24 flame detectors. *Model 74000 is no longer being manufactured.

  12. Neutrino Detectors

    NASA Astrophysics Data System (ADS)

    von Feilitzsch, Franz; Lanfranchi, Jean-Côme; Wurm, Michael

    The neutrino was postulated by Wolfgang Pauli in the early 1930s, but could only be detected for the first time in the 1950s. Ever since scientists all around the world have worked on the detection and understanding of this particle which so scarcely interacts with matter. Depending on the origin and nature of the neutrino, various types of experiments have been developed and operated. In this entry, we will review neutrino detectors in terms of neutrino energy and associated detection technique as well as the scientific outcome of some selected examples. After a brief historical introduction, the detection of low-energy neutrinos originating from nuclear reactors or from the Earth is used to illustrate the principles and difficulties which are encountered in detecting neutrinos. In the context of solar neutrino spectroscopy, where the neutrino is used as a probe for astrophysics, three different types of neutrino detectors are presented - water Čerenkov, radiochemical, and liquid-scintillator detectors. Moving to higher neutrino energies, we discuss neutrinos produced by astrophysical sources and from accelerators. The entry concludes with an overview of a selection of future neutrino experiments and their scientific goals.

  13. Studies of beam induced radiation for experiment 735 at the CO interaction region and its effect on detector components

    SciTech Connect

    Turkot, F.; Hojvat, C.; Anderson, W.; Lindsey, C.S.; Biswas, N.; Piekarz, J.; Bujak, A.

    1985-06-12

    A series of measurement is reported that were conducted to evaluate the amount of radiation present in the Fermilab Collider tunnel under different circumstances. Also to be determined is the effect of radiation on scintillators, phototubes, and their electronics, possible damage to drift chamber wires due to high counting rates and possible damage to the drift chamber electronics. Background and resulting trigger rates are evaluated and the effect of local shielding is studied. Results of radiation measurements made during beam-on operation are presented. The detectors used include: two arrays of LiF crystal dosemeters, three scintillation counter telescopes, a modified ion chamber, and six sample pieces of Bicron plastic scintillators. (LEW)

  14. SU-F-18C-05: Characterization of a Silicon Strip Photon-Counting Detector in the Presence of Compton Scatter: A Simulation Study

    SciTech Connect

    Ziemer, B; Ding, H; Cho, H

    2014-06-15

    Purpose: To investigate the effect of Compton scatter on detection efficiency and charge-sharing for a Si strip photon-counting detector as a function of pixel pitch, slice thickness and total pixel length. Methods: A CT imaging system employing a silicon photon-counting detector was implemented using the GATE Monte Carlo package. A focal spot size of 300 µm, magnification of 1.33, and pixel pitches of 0.1 and 0.5mm were initially investigated. A 60 kVp spectrum with 3 mm Al filter was used and energy spectral degradation based on a prototype detector was simulated. To study charge-sharing, a single pixel was illuminated, and the detector response in neighboring pixels was investigated. A longitudinally semiinfinite detector was simulated to optimize the quantum detection efficiency of the imaging system as a function of pixel pitch, slice thickness and depth of interaction. A 2.5 mm thick tungsten plate with a 0.01 mm by 1.5 mm slit was implemented to calculate the modulation transfer function (MTF) from projection-based images. A threshold of 15 keV was implemented in the detector simulation. The preliminary charge sharing investigation results considered only scattering effects and the detector electronics related factors were neglected. Results: Using a 15 keV threshold, 1% of the pixel charge migrated into neighboring pixels with a pixel size of 0.1×0.1 mm{sup 2}. The quantum detection efficiency was 77%, 84%, 87% and 89% for 15 mm, 22.5 mm, 30 mm, and 45 mm length silicon detector pixels, respectively. For a pixel pitch of 0.1 mm, the spatial frequency at 10% of the maximum MTF was found to be 5.2 lp/mm. This agreed with an experimental MTF measurement of 5.3 lp/mm with a similar detector configuration. Conclusion: Using optimized design parameters, Si strip photon-counting detectors can offer high detection efficiency and spatial resolution even in the presence of Compton scatter.

  15. A feasibility study of a data acquisition system for a silicon strip detector with a digital readout scheme

    NASA Astrophysics Data System (ADS)

    Ikeda, Hirokazu; Ikeda, Mitsuo; Inaba, Susumu; Tanaka, Manobu

    1993-06-01

    We describe a prototype data acquisition system for a silicon strip detector, which has been developed in terms of a digital readout scheme. The system consists of a master timing generator, readout controller, and a detector emulator card on which we use custom VLSI shift registers with operating clock frequency of 30 MHz.

  16. Next-generation detectors for x-ray astronomy

    NASA Astrophysics Data System (ADS)

    Ambrosi, Richard M.; Holland, Andrew D.; Mukerjee, Kallol; Keay, Adam; Turner, Martin J. L.; Abbey, Antony F.; Hutchinson, Ian B.; Ashton, T. J. R.; Beardmore, Andrew P.; Short, Alexander D. T.; Pool, Peter J.; Burt, David; Vernon, D.

    2004-09-01

    The next generation of X-ray astronomy instruments will require position sensitive detectors in the form of charge coupled devices (CCDs) for X-ray spectroscopy and imaging that will have the ability to probe the X-ray universe with a greater efficiency. This will require the development of CCDs with structures that will improve on the quantum efficiency of the current state of the art over a broader spectral range in addition to reducing spectral features, which may affect spectral resolution and signal to background levels. These devices will also have to be designed to withstand the harsh radiation environments associated with orbits that extend beyond the Earth"s magnetosphere. The next generation X-ray telescopes will incorporate larger X-ray optics that will allow deeper observations of the X-ray universe and sensors will have to compensate for this by an increased readout speed. This study will aim to describe some of the results obtained from test CCD structures that may fit many of the requirements described above.

  17. Feasibility study of sparse-angular sampling and sinogram interpolation in material decomposition with a photon-counting detector

    NASA Astrophysics Data System (ADS)

    Kim, Dohyeon; Jo, Byungdu; Park, Su-Jin; Kim, Hyemi; Kim, Hee-Joung

    2016-03-01

    Spectral computed tomography (SCT) is a promising technique for obtaining enhanced image with contrast agent and distinguishing different materials. We focused on developing the analytic reconstruction algorithm in material decomposition technique with lower radiation exposure and shorter acquisition time. Sparse-angular sampling can reduce patient dose and scanning time for obtaining the reconstruction images. In this study, the sinogram interpolation method was used to improve the quality of material decomposed images in sparse angular sampling. A prototype of spectral CT system with 64 pixels CZT-based photon counting detector was used. The source-to-detector distance and the source-tocenter of rotation distance were 1200 and 1015 mm, respectively. The x-ray spectrum at 90 kVp with a tube current of 110 μA was used. Two energy bins (23-33 keV and 34-44 keV) were set to obtain the two images for decomposed iodine and calcification. We used PMMA phantom and its height and radius were 50 mm and 17.5 mm, respectively. The phantom contained 4 materials including iodine, gadolinium, calcification, and liquid state lipid. We evaluated the signal to noise ratio (SNR) of materials to examine the significance of sinogram interpolation method. The decomposed iodine and calcification images were obtained by projection based subtraction method using two energy bins with 36 projection data. The SNR in decomposed images were improved by using sinogram interpolation method. And these results indicated that the signal of decomposed material was increased and the noise of decomposed material was reduced. In conclusion, the sinogram interpolation method can be used in material decomposition method with sparse-angular sampling.

  18. A high resolution animal PET scanner using compact PS-PMT detectors

    SciTech Connect

    Watanabe, M.; Okada, H.; Shimizu, K.; Omura, T.

    1996-12-31

    A new high resolution PET scanner dedicated to animal studies has been designed, built and tested. The system utilizes 240 block detectors, each of which consists of a new compact position-sensitive photomultiplier tube (PS-PMT) and an 8 x 4 BGO array. A total number of 7,680 crystals (480 per ring) are positioned to form a 508 mm diameter of 16 detector rings with 7.2 mm pitch and 114 mm axial field of view (FOV). The system is designed to perform activation studies using a monkey in a sitting position. The data can be acquired in either 2D or 3D mode, where the slice collimators are retracted in 3D mode. The transaxial resolution is 2.6 mm FWHM at the center of the FOV, and the average axial resolution on the axis of the ring is 3.3 mm FWHM in the direct slice and 3.2 mm FWHM in the cross slice. The scatter fraction, sensitivity and count rate performance were evaluated for a 10 cm diameter cylindrical phantom. The total system sensitivity is 2.3 kcps/kBq/ml in 2D mode and 22.8 kcps/kBq/ml in 3D mode. The noise equivalent count rate with 3D mode is equivalent to that with 2D mode at five times higher radioactivity level. The applicable imaging capabilities of the scanner was demonstrated by animal studies with a monkey.

  19. Dust Detector

    NASA Technical Reports Server (NTRS)

    Kelley, M. C.

    2001-01-01

    We discuss a recent sounding rocket experiment which found charged dust in the Earth's tropical mesosphere. The dust detector was designed to measure small (5000 - 10000 amu.) charged dust particles, most likely of meteoric origin. A 5 km thick layer of positively charged dust was found at an altitude of 90 km, in the vicinity of an observed sporadic sodium layer and sporadic E layer. The observed dust was positively charged in the bulk of the dust layer, but was negatively charged near the bottom.

  20. Ion detector

    DOEpatents

    Tullis, Andrew M.

    1987-01-01

    An improved ion detector device of the ionization detection device chamber ype comprises an ionization chamber having a central electrode therein surrounded by a cylindrical electrode member within the chamber with a collar frictionally fitted around at least one of the electrodes. The collar has electrical contact means carried in an annular groove in an inner bore of the collar to contact the outer surface of the electrode to provide electrical contact between an external terminal and the electrode without the need to solder leads to the electrode.

  1. Design and study of a coplanar grid array CdZnTe detector for improved spatial resolution.

    PubMed

    Ma, Yuedong; Xiao, Shali; Yang, Guoqiang; Zhang, Liuqiang

    2014-12-01

    Coplanar grid (CPG) CdZnTe detectors have been used as gamma-ray spectrometers for years. Comparing with pixelated CdZnTe detectors, CPG CdZnTe detectors have either no or poor spatial resolution, which directly limits its use in imaging applications. To address the issue, a 2×2 CPG array CdZnTe detector with dimensions of 7×7×5mm(3) was fabricated. Each of the CPG pairs in the detector was moderately shrunk in size and precisely designed to improve the spatial resolution while maintaining good energy resolution, considering the charge loss at the surface between the strips of each CPG pairs. Preliminary measurements were demonstrated at an energy resolution of 2.7-3.9% for the four CPG pairs using 662keV gamma rays and with a spatial resolution of 3.3mm, which is the best spatial resolution ever achieved for CPG CdZnTe detectors. The results reveal that the CPG CdZnTe detector can also be applied to imaging applications at a substantially higher spatial resolution.

  2. Experimental study on the 3D image reconstruction in a truncated Archimedean-like spiral geometry with a long-rectangular detector and its image characteristics

    NASA Astrophysics Data System (ADS)

    Hong, Daeki; Cho, Heemoon; Cho, Hyosung; Choi, Sungil; Je, Uikyu; Park, Yeonok; Park, Chulkyu; Lim, Hyunwoo; Park, Soyoung; Woo, Taeho

    2015-11-01

    In this work, we performed a feasibility study on the three-dimensional (3D) image reconstruction in a truncated Archimedean-like spiral geometry with a long-rectangular detector for application to high-accurate, cost-effective dental x-ray imaging. Here an x-ray tube and a detector rotate together around the rotational axis several times and, concurrently, the detector moves horizontally in the detector coordinate at a constant speed to cover the whole imaging volume during the projection data acquisition. We established a table-top setup which mainly consists of an x-ray tube (60 kVp, 5 mA), a narrow CMOS-type detector (198-μm pixel resolution, 184 (W)×1176 (H) pixel dimension), and a rotational stage for sample mounting and performed a systematic experiment to demonstrate the viability of the proposed approach to volumetric dental imaging. For the image reconstruction, we employed a compressed-sensing (CS)-based algorithm, rather than a common filtered-backprojection (FBP) one, for more accurate reconstruction. We successfully reconstructed 3D images of considerably high quality and investigated the image characteristics in terms of the image value profile, the contrast-to-noise ratio (CNR), and the spatial resolution.

  3. Monte Carlo Simulation Study on the Time Resolution of a PMT-Quadrant-Sharing LSO Detector Block for Time-of-Flight PET

    PubMed Central

    Liu, Shitao; Li, Hongdi; Zhang, Yuxuan; Ramirez, Rocio A.; Baghaei, Hossain; An, Shaohui; Wang, Chao; Liu, Jiguo; Wong, Wai-Hoi

    2010-01-01

    We developed a detailed Monte Carlo simulation method to study the time resolution of detectors for time-of-flight positron emission tomography (TOF PET). The process of gamma ray interaction in detectors, scintillation light emission and transport inside the detectors, the photoelectron generation and anode signal generation in the photomultiplier tube (PMT), and the electronics process of discriminator are simulated. We tested this simulation method using published experimental data, and found that it can generate reliable results. Using this method, we simulated the time resolution for a 13 × 13 detector block of 4 × 4 × 20 mm3 lutetium orthosilicate (LSO) crystals coupled to four 2-inch PMTs using PMT-quadrant-sharing (PQS) technology. We analyzed the effects of several factors, including the number of photoelectrons, light transport, transit time spread (TTS), and the depth of interaction (DOI). The simulation results indicated that system time resolution of 360 ps should be possible with currently available fast PMTs. This simulation method can also be used to simulate the time resolution of other detector design method. PMID:20559457

  4. Silicon photomultiplier as a detector of Cherenkov photons

    NASA Astrophysics Data System (ADS)

    Korpar, S.; Dolenec, R.; Hara, K.; Iijima, T.; Križan, P.; Mazuka, Y.; Pestotnik, R.; Stanovnik, A.; Yamaoka, M.

    2008-09-01

    A novel photon detector—i.e. the silicon photomultiplier—whose main advantage over conventional photomultiplier tubes is the operation in high magnetic fields, has been tested as a photon detector in a proximity focusing RICH with aerogel radiator. This type of RICH counter is proposed for the upgrade of the Belle detector at the KEK B-factory. Recently produced silicon photomultipliers show less noise and have larger size, which are important issues for a large area photon detector. We measured the single photon pulse height distribution, the timing resolution and the position sensitivity for different silicon photomultipliers (Hamamatsu MPPC HC025, HC050, and HC100). The silicon photomultipliers were then used to detect Cherenkov photons emitted by cosmic ray particles in a proximity focusing aerogel RICH. Various light guides were investigated in order to increase the detection efficiency.

  5. Photocurrent spectrum study of a quantum dot single-photon detector based on resonant tunneling effect with near-infrared response

    SciTech Connect

    Weng, Q. C.; An, Z. H. E-mail: luwei@mail.sitp.ac.cn; Xiong, D. Y.; Zhu, Z. Q.; Zhang, B.; Chen, P. P.; Li, T. X.; Lu, W. E-mail: luwei@mail.sitp.ac.cn

    2014-07-21

    We present the photocurrent spectrum study of a quantum dot (QD) single-photon detector using a reset technique which eliminates the QD's “memory effect.” By applying a proper reset frequency and keeping the detector in linear-response region, the detector's responses to different monochromatic light are resolved which reflects different detection efficiencies. We find the reset photocurrent tails up to 1.3 μm wavelength and near-infrared (∼1100 nm) single-photon sensitivity is demonstrated due to interband transition of electrons in QDs, indicating the device a promising candidate both in quantum information applications and highly sensitive imaging applications operating in relative high temperatures (>80 K).

  6. Possibility of absolute calibration of analog detectors by using parametric downconversion: a systematic study

    SciTech Connect

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

    2006-10-15

    Prompted by the need for various studies ranging from quantum information to foundations of quantum mechanics, we systematically study the possibility of the absolute calibration of analog photodetectors based on the properties of parametric amplifiers. Our results show that such a method can be effectively developed with interesting possible applications in metrology.

  7. 3D dose verification with polymer gel detectors of brain-spine match line for proton pencil beam cranio-spinal: A preliminary study

    NASA Astrophysics Data System (ADS)

    Avery, S.; Cardin, A.; Lin, L.; Kirk, M.; Kassaee, A.; Maryanski, M. J.

    2015-01-01

    This paper is intended as a preliminary study to demonstrate the quality assurance benefits from polymer gel detectors for proton pencil beam cranio-spinal treatments. A stable gel type was selected for protons to suppress the LET dependence at the end of the Bragg peak. The depth dose distributions in the gels were examined with regard of its dose dependences and compared to baseline measurements. The preliminary experimental results indicate polymer gel detectors may be able to verify dose in three dimensions along match line for proton therapy treatments.

  8. A study of low-noise preamplifier systems for use with room temperature mercuric iodide /HgI2/ X-ray detectors

    NASA Technical Reports Server (NTRS)

    Iwanczyk, J. S.; Huth, G. C.; Del Duca, A.; Schnepple, W.; Dabrowski, A. J.

    1981-01-01

    An analysis of different preamplification systems for use with room temperature mercuric iodide X-ray detectors has been performed. Resistor-, drain-, and light-feedback preamplifiers have been studied. Energy resolution values of 295 eV (FWHM) for an Fe-55 source (5.9 keV) and 225 eV (FWHM) for a pulser have been obtained with both the detector and the input FET at room temperature using a pulsed-light feedback preamplifier. Improvement in energy resolution by cooling the input FET using a small Peltier element has been discussed.

  9. A study of low-noise preamplifier systems for use with room temperature mercuric iodide /HgI2/ X-ray detectors

    NASA Astrophysics Data System (ADS)

    Iwanczyk, J. S.; Huth, G. C.; del Duca, A.; Schnepple, W.; Dabrowski, A. J.

    1981-02-01

    An analysis of different preamplification systems for use with room temperature mercuric iodide X-ray detectors has been performed. Resistor-, drain-, and light-feedback preamplifiers have been studied. Energy resolution values of 295 eV (FWHM) for an Fe-55 source (5.9 keV) and 225 eV (FWHM) for a pulser have been obtained with both the detector and the input FET at room temperature using a pulsed-light feedback preamplifier. Improvement in energy resolution by cooling the input FET using a small Peltier element has been discussed.

  10. Study of low noise preamplifier systems for use with room temperature mercuric iodide (HgI/sub 2/) x-ray detectors

    SciTech Connect

    Iwanczyk, J.S.; Dabrowski, A.J.; Huth, G.C.; Del Duca, A.; Schenpple, W.

    1980-01-01

    An analysis of different preamplification systems for use with room temperature mercuric iodide x-ray detectors has been performed. Resistor-, drain-, and light-feedback preamplifiers have been studied. Energy resolution of 295 eV (FWHM) for Fe-55 source (5.9 keV) and 225 eV (FWHM) for the pulser have been obtained with both the detector and the input FET at room temperature using the pulsed-light feedback preamplifier. It has been shown that cooling the input FET using a small Peltier element allows the energy resolution to be improved up to 25%.

  11. Smoke Detector Resource Catalog.

    ERIC Educational Resources Information Center

    Portugill, Jestyn, Ed.; Powell, Pamela, Ed.

    This manual is one of a series developed for public education on smoke detectors. First, basic facts are given including guidelines for selection and purchasing, installation, maintenance, and what to do if the alarm goes off. Second, five case studies are presented which are examples of public education programs. (The script to one slide…

  12. Worldwide Activities towards a Future Circular Collider: Physics and Detector Studies

    NASA Astrophysics Data System (ADS)

    Mangano, Michelangelo

    2015-04-01

    Collider rings with circumference in the range of 50-100 km could host electron-positron colliders with center-of-mass energies up to 350 GeV, and proton-proton colliders up to 100 TeV. Two-stage projects, along the lines of the LEP-LHC complex, are under study by the high-energy physics community worldwide. The physics potential of such a future facility spans from improving by orders of magnitude the precision study of the Higgs boson, to extending by a factor of 10 the mass reach for the search of new particles. The talk will review the physics opportunities and the challenges that are emerging from the current studies.

  13. Study of muon bundles from extensive air showers with the ALICE detector at CERN LHC

    NASA Astrophysics Data System (ADS)

    Shtejer, K.

    2016-05-01

    ALICE is one of four large experiments at the CERN Large Hadron Collider, specially designed to study particle production in ultra-relativistic heavy-ion collisions. Located 52 meters underground with 28 meters of overburden rock, it has also been used to detect muons produced by cosmic-ray interactions in the upper atmosphere. The large size and excellent tracking capability of the ALICE Time Projection Chamber are exploited to study the muonic component of extensive air showers. We present the multiplicity distribution of these atmospheric muons and its comparison with Monte Carlo simulations. The latest version of the QGSJET hadronic interaction model was used to simulate the development of the resulting air showers. High multiplicity events containing more than 100 reconstructed muons were also studied. Similar events have been studied in previous underground experiments such as ALEPH and DELPHI at LEP without satisfactory explanations for the frequency of the highest multiplicity events. We demonstrate that the high muon-multiplicity events observed in ALICE stem from primary cosmic rays with energies above 1016 eV and that the frequency of these events can be successfully described by assuming a heavy mass composition of primary cosmic rays in this energy range.

  14. A study of indoor radon levels in rural dwellings of Ezine (Canakkale, Turkey) using solid-state nuclear track detectors.

    PubMed

    Orgün, Y; Altinsoy, N; Sahin, S Y; Ataksor, B; Celebi, N

    2008-01-01

    Indoor radon activity level and radon effective dose (ED) rate have been carried out in the rural dwellings of Ezine (Canakkale) during the summer season using Radosys-2000, a complete set suitable to radon concentration measurements with CR-39 plastic alpha track detectors. The range of radon concentration varied between 9 and 300 Bq m(-3), with an average of 67.9 (39.9 SD) Bq m(-3). Assuming an indoor occupancy factor of 0.8 and 0.4 for the equilibrium factor of radon indoors, it has been found that the 222Rn ED rate in the dwellings studied ranges from 0.4 to 5.2 mSv y(-1), with an average value of 1.7 (1.0) mSv y(-1). There is a possibility that low radon concentrations exist indoors during the summer season in the study area because of relatively high ventilation rates in the dwellings. A winter survey will be needed for future estimation of the annual ED.

  15. Monte Carlo simulation studies on scintillation detectors and image reconstruction of brain-phantom tumors in TOFPET

    PubMed Central

    Mondal, Nagendra Nath

    2009-01-01

    This study presents Monte Carlo Simulation (MCS) results of detection efficiencies, spatial resolutions and resolving powers of a time-of-flight (TOF) PET detector systems. Cerium activated Lutetium Oxyorthosilicate (Lu2SiO5: Ce in short LSO), Barium Fluoride (BaF2) and BriLanCe 380 (Cerium doped Lanthanum tri-Bromide, in short LaBr3) scintillation crystals are studied in view of their good time and energy resolutions and shorter decay times. The results of MCS based on GEANT show that spatial resolution, detection efficiency and resolving power of LSO are better than those of BaF2 and LaBr3, although it possesses inferior time and energy resolutions. Instead of the conventional position reconstruction method, newly established image reconstruction (talked about in the previous work) method is applied to produce high-tech images. Validation is a momentous step to ensure that this imaging method fulfills all purposes of motivation discussed by reconstructing images of two tumors in a brain phantom. PMID:20098551

  16. Cross section measurements for γ-process studies using a LEPS detector

    NASA Astrophysics Data System (ADS)

    Szücs, T.; Kiss, GG; Rauscher, T.; Török, Zs; Halász, Z.; Fülöp, Zs; Gyürky, Gy; Somorjai, E.

    2016-01-01

    In this paper we present the ongoing experiments at ATOMKI related to our systematic γ-process studies. These studies are intended to enlarge the limited experimental database from α-induced reactions on nuclei in the heavier mass range of the γ -process. In all presented cases the activation method was used. The details of the cross section measurements and preliminary results on115In(α,n)118mSb, 115In(α,γ)119Sb 162Er(α,n)165Yb, 162Er(α,γ)166Yb, 164Er(α,n)167Yb, 166Er(α,n)169Yb 191Ir(α,n)194Au, 191Ir(α,γ)195Au, 193Ir(α,n)196mAu, 193Ir(α,n)196Au reactions are presented.

  17. Oscillator detector

    SciTech Connect

    Potter, B.M.

    1980-05-13

    An alien liquid detector employs a monitoring element and an oscillatory electronic circuit for maintaining the temperature of the monitoring element substantially above ambient temperature. The output wave form, eg., frequency of oscillation or wave shape, of the oscillatory circuit depends upon the temperaturedependent electrical characteristic of the monitoring element. A predetermined change in the output waveform allows water to be discriminated from another liquid, eg., oil. Features of the invention employing two thermistors in two oscillatory circuits include positioning one thermistor for contact with water and the other thermistor above the oil-water interface to detect a layer of oil if present. Unique oscillatory circuit arrangements are shown that achieve effective thermistor action with an economy of parts and energizing power. These include an operational amplifier employed in an astable multivibrator circuit, a discrete transistor-powered tank circuit, and use of an integrated circuit chip.

  18. Monte Carlo simulation using the PENELOPE code with an ant colony algorithm to study MOSFET detectors

    NASA Astrophysics Data System (ADS)

    Carvajal, M. A.; García-Pareja, S.; Guirado, D.; Vilches, M.; Anguiano, M.; Palma, A. J.; Lallena, A. M.

    2009-10-01

    In this work we have developed a simulation tool, based on the PENELOPE code, to study the response of MOSFET devices to irradiation with high-energy photons. The energy deposited in the extremely thin silicon dioxide layer has been calculated. To reduce the statistical uncertainties, an ant colony algorithm has been implemented to drive the application of splitting and Russian roulette as variance reduction techniques. In this way, the uncertainty has been reduced by a factor of ~5, while the efficiency is increased by a factor of above 20. As an application, we have studied the dependence of the response of the pMOS transistor 3N163, used as a dosimeter, with the incidence angle of the radiation for three common photons sources used in radiotherapy: a 60Co Theratron-780 and the 6 and 18 MV beams produced by a Mevatron KDS LINAC. Experimental and simulated results have been obtained for gantry angles of 0o, 15o, 30o, 45o, 60o and 75o. The agreement obtained has permitted validation of the simulation tool. We have studied how to reduce the angular dependence of the MOSFET response by using an additional encapsulation made of brass in the case of the two LINAC qualities considered.

  19. Monte Carlo simulation using the PENELOPE code with an ant colony algorithm to study MOSFET detectors.

    PubMed

    Carvajal, M A; García-Pareja, S; Guirado, D; Vilches, M; Anguiano, M; Palma, A J; Lallena, A M

    2009-10-21

    In this work we have developed a simulation tool, based on the PENELOPE code, to study the response of MOSFET devices to irradiation with high-energy photons. The energy deposited in the extremely thin silicon dioxide layer has been calculated. To reduce the statistical uncertainties, an ant colony algorithm has been implemented to drive the application of splitting and Russian roulette as variance reduction techniques. In this way, the uncertainty has been reduced by a factor of approximately 5, while the efficiency is increased by a factor of above 20. As an application, we have studied the dependence of the response of the pMOS transistor 3N163, used as a dosimeter, with the incidence angle of the radiation for three common photons sources used in radiotherapy: a (60)Co Theratron-780 and the 6 and 18 MV beams produced by a Mevatron KDS LINAC. Experimental and simulated results have been obtained for gantry angles of 0 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees and 75 degrees. The agreement obtained has permitted validation of the simulation tool. We have studied how to reduce the angular dependence of the MOSFET response by using an additional encapsulation made of brass in the case of the two LINAC qualities considered. PMID:19794247

  20. Design of an advanced positron emission tomography detector system and algorithms for imaging small animal models of human disease

    NASA Astrophysics Data System (ADS)

    Foudray, Angela Marie Klohs

    Detecting, quantifying and visualizing biochemical mechanism in a living system without perturbing function is the goal of the instrument and algorithms designed in this thesis. Biochemical mechanisms of cells have long been known to be dependent on the signals they receive from their environment. Studying biological processes of cells in-vitro can vastly distort their function, since you are removing them from their natural chemical signaling environment. Mice have become the biological system of choice for various areas of biomedical research due to their genetic and physiological similarities with humans, the relatively low cost of their care, and their quick breeding cycle. Drug development and efficacy assessment along with disease detection, management, and mechanism research all have benefited from the use of small animal models of human disease. A high resolution, high sensitivity, three-dimensional (3D) positioning positron emission tomography (PET) detector system was designed through device characterization and Monte Carlo simulation. Position-sensitive avalanche photodiodes (PSAPDs) were characterized in various packaging configurations; coupled to various configurations of lutetium oxyorthosilicate (LSO) scintillation crystals. Forty novelly packaged final design devices were constructed and characterized, each providing characteristics superior to commercially available scintillation detectors used in small animal imaging systems: ˜1mm crystal identification, 14-15% of 511 keV energy resolution, and averaging 1.9 to 5.6 ns coincidence time resolution. A closed-cornered box-shaped detector configuration was found to provide optimal photon sensitivity (˜10.5% in the central plane) using dual LSO-PSAPD scintillation detector modules and Monte Carlo simulation. Standard figures of merit were used to determine optimal system acquisition parameters. A realistic model for constituent devices was developed for understanding the signals reported by the