A novel method to calibrate DOI function of a PET detector with a dual-ended-scintillator readout.

PubMed

Shao, Yiping; Yao, Rutao; Ma, Tianyu

2008-12-01

The detection of depth-of-interaction (DOI) is a critical detector capability to improve the PET spatial resolution uniformity across the field-of-view and will significantly enhance, in particular, small bore system performance for brain, breast, and small animal imaging. One promising technique of DOI detection is to use dual-ended-scintillator readout that uses two photon sensors to detect scintillation light from both ends of a scintillator array and estimate DOI based on the ratio of signals (similar to Anger logic). This approach needs a careful DOI function calibration to establish accurate relationship between DOI and signal ratios, and to recalibrate if the detection condition is shifted due to the drift of sensor gain, bias variations, or degraded optical coupling, etc. However, the current calibration method that uses coincident events to locate interaction positions inside a single scintillator crystal has severe drawbacks, such as complicated setup, long and repetitive measurements, and being prone to errors from various possible misalignments among the source and detector components. This method is also not practically suitable to calibrate multiple DOI functions of a crystal array. To solve these problems, a new method has been developed that requires only a uniform flood source to irradiate a crystal array without the need to locate the interaction positions, and calculates DOI functions based solely on the uniform probability distribution of interactions over DOI positions without knowledge or assumption of detector responses. Simulation and experiment have been studied to validate the new method, and the results show that the new method, with a simple setup and one single measurement, can provide consistent and accurate DOI functions for the entire array of multiple scintillator crystals. This will enable an accurate, simple, and practical DOI function calibration for the PET detectors based on the design of dual-ended-scintillator readout. In addition, the new method can be generally applied to calibrating other types of detectors that use the similar dual-ended readout to acquire the radiation interaction position.

A novel method to calibrate DOI function of a PET detector with a dual-ended-scintillator readout

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

Shao Yiping; Yao Rutao; Ma Tianyu

The detection of depth-of-interaction (DOI) is a critical detector capability to improve the PET spatial resolution uniformity across the field-of-view and will significantly enhance, in particular, small bore system performance for brain, breast, and small animal imaging. One promising technique of DOI detection is to use dual-ended-scintillator readout that uses two photon sensors to detect scintillation light from both ends of a scintillator array and estimate DOI based on the ratio of signals (similar to Anger logic). This approach needs a careful DOI function calibration to establish accurate relationship between DOI and signal ratios, and to recalibrate if the detectionmore » condition is shifted due to the drift of sensor gain, bias variations, or degraded optical coupling, etc. However, the current calibration method that uses coincident events to locate interaction positions inside a single scintillator crystal has severe drawbacks, such as complicated setup, long and repetitive measurements, and being prone to errors from various possible misalignments among the source and detector components. This method is also not practically suitable to calibrate multiple DOI functions of a crystal array. To solve these problems, a new method has been developed that requires only a uniform flood source to irradiate a crystal array without the need to locate the interaction positions, and calculates DOI functions based solely on the uniform probability distribution of interactions over DOI positions without knowledge or assumption of detector responses. Simulation and experiment have been studied to validate the new method, and the results show that the new method, with a simple setup and one single measurement, can provide consistent and accurate DOI functions for the entire array of multiple scintillator crystals. This will enable an accurate, simple, and practical DOI function calibration for the PET detectors based on the design of dual-ended-scintillator readout. In addition, the new method can be generally applied to calibrating other types of detectors that use the similar dual-ended readout to acquire the radiation interaction position.« less

New Opportunities in Decay Spectroscopy with the GRIFFIN and DESCANT Arrays

NASA Astrophysics Data System (ADS)

Bildstein, V.; Andreoiu, C.; Ball, G. C.; Ballast, T.; Bartlett, C.; Bender, P. C.; Bernier, N.; Bianco, L.; Bishop, D.; Brennan, D.; Bruhn, T.; Cheeseman, A.; Churchman, R.; Ciccone, S.; Davids, B.; Demand, G.; Dillmann, I.; Garnsworthy, A. B.; Garrett, P. E.; Georges, S.; Hackman, G.; Hadinia, B.; Kokke, R.; Krücken, R.; Linn, Y.; Lim, C.; Martin, J.-P.; Miller, D.; Mills, W. J.; Morrison, L. N.; Ohlmann, C. A.; Park, J.; Pearson, C. J.; Pore, J. L.; Rajabali, M. M.; Rand, E. T.; Rizwan, U.; Sarazin, F.; Shaw, B.; Starosta, K.; Svensson, C. E.; Sumithrarachchi, C.; Unsworth, C.; Voss, P.; Wang, Z. M.; Williams, J.; Wong, J.; Wong, S.

The GRIFFIN (Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei) project is a major upgrade of the decay spectroscopy capabilities at TRIUMF-ISAC. GRIFFIN will replace the 8π spectrometer with an array of up to 16 large-volume HPGe clover detectors and use a state-of-the-art digital data acquisition system. The existing ancillary detector systems that had been developed for 8π, such as the SCEPTAR array for β-tagging, PACES for high-resolution internal conversion electron spectroscopy, and the DANTE array of LaBr3/BaF2 scintillators for fast γ-ray timing, will be used with GRIFFIN. GRIFFIN can also accommodate the new neutron detector array DESCANT (Deuterated Scintillator Array for Neutron Tagging), enabling the study of β-delayed neutron emitters. DESCANT consists of up to 70 detectors, each filled with approximately 2 liters of deuterated benzene, a liquid scintillator that provides pulse-shape discrimination (PSD) capabilities to distinguish between neutrons and γ-rays interacting with the detector. In addition, the anisotropic nature of n-d scattering as compared to the isotropic n-p scattering allows for the determination of the neutron energy spectrum directly from the pulse-height spectrum, complementing the time-of-flight (TOF) information. The installation of GRIFFIN is under way and first experiments are planned for the fall of 2014. The array will be completed in 2015 with the full complement of 16 clovers. DESCANT will be tested coupled with GRIFFIN in spring of 2015.

Maximum likelihood positioning and energy correction for scintillation detectors

NASA Astrophysics Data System (ADS)

Lerche, Christoph W.; Salomon, André; Goldschmidt, Benjamin; Lodomez, Sarah; Weissler, Björn; Solf, Torsten

2016-02-01

An algorithm for determining the crystal pixel and the gamma ray energy with scintillation detectors for PET is presented. The algorithm uses Likelihood Maximisation (ML) and therefore is inherently robust to missing data caused by defect or paralysed photo detector pixels. We tested the algorithm on a highly integrated MRI compatible small animal PET insert. The scintillation detector blocks of the PET gantry were built with the newly developed digital Silicon Photomultiplier (SiPM) technology from Philips Digital Photon Counting and LYSO pixel arrays with a pitch of 1 mm and length of 12 mm. Light sharing was used to readout the scintillation light from the 30× 30 scintillator pixel array with an 8× 8 SiPM array. For the performance evaluation of the proposed algorithm, we measured the scanner’s spatial resolution, energy resolution, singles and prompt count rate performance, and image noise. These values were compared to corresponding values obtained with Center of Gravity (CoG) based positioning methods for different scintillation light trigger thresholds and also for different energy windows. While all positioning algorithms showed similar spatial resolution, a clear advantage for the ML method was observed when comparing the PET scanner’s overall single and prompt detection efficiency, image noise, and energy resolution to the CoG based methods. Further, ML positioning reduces the dependence of image quality on scanner configuration parameters and was the only method that allowed achieving highest energy resolution, count rate performance and spatial resolution at the same time.

Gross beta determination in drinking water using scintillating fiber array detector.

PubMed

Lv, Wen-Hui; Yi, Hong-Chang; Liu, Tong-Qing; Zeng, Zhi; Li, Jun-Li; Zhang, Hui; Ma, Hao

2018-04-04

A scintillating fiber array detector for measuring gross beta counting is developed to monitor the real-time radioactivity in drinking water. The detector, placed in a stainless-steel tank, consists of 1096 scintillating fibers, both sides of which are connected to a photomultiplier tube. The detector parameters, including working voltage, background counting rate and stability, are tested, and the detection efficiency is calibrated using standard potassium chloride solution. Water samples are measured with the detector and the results are compared with those by evaporation method. The results show consistency with those by evaporation method. The background counting rate of the detector is 38.131 ± 0.005 cps, and the detection efficiency for β particles is 0.37 ± 0.01 cps/(Bq/l). The MDAC of this system can be less than 1.0 Bq/l for β particles in 120 min without pre-concentration. Copyright © 2018 Elsevier Ltd. All rights reserved.

Design Study of DESCANT - DEuterated SCintillator Array for Neutron Tagging

NASA Astrophysics Data System (ADS)

Wong, James; Garrett, P. E.

2007-10-01

The fusion-evaporation reaction has been a useful tool for studying nuclei. A program of such reactions is being planned to take place at the TRIUMF facility in Vancouver, Canada using the TIGRESS array of gamma-ray detectors. A particular advantage of using these reactions is that they probe nuclei at moderate-to-high angular momenta. It would be of great interest to extend the study of high-spin states to neutron-rich systems. Following the formation of the fused compound system, the highly-excited state may lose energy by ``evaporating'' particles. Neutron evaporation is the predominant decay mode from neutron-rich compound systems so neutron detectors will be required. The probability of neutrons multiple scattering is quite high so a detector array must be able to differentiate between multiple neutrons evaporating from the reaction and a single neutron scattering multiple times. To address this issue we investigate the use of a novel neutron detector array -- one based on an array of deuterated liquid scintillators as neutron detectors. Results from early feasibility tests will be presented, along with the status of our GEANT4 simulations of the array performance.

The Extensive Air Shower Experiment Kascade-Grande

NASA Astrophysics Data System (ADS)

Kang, Donghwa; Apel, W. D.; Arteaga, J. C.; Badea, F.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Finger, M.; Fuhrmann, D.; Ghia, P. L.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kickelbick, D.; Klages, H. O.; Kolotaev, Y.; Łuczak, P.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schatz, G.; Schieler, H.; Schröder, F.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero, G. C.; Ulrich, H.; van Buren, J.; Walkowiak, W.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.

The extensive air shower experiment KASCADE-Grande (KArlsruhe Shower Core and Array DEtector and Grande array) is located on site of the Forschungszentrum Karlsruhe in Germany. The original KASCADE experiment consisted of a densely packed scintillator array with unshielded and shielded detectors for the measurement of the electromagnetic and muonic shower component independently, as well as muon tracking devices and a hadron calorimeter. The Grande array as an extension of KASCADE consists of 37 scintillation detector stations covering an area of 700×700 m2. The main goal for the combined measurements of KASCADE and Grande is the investigation of the energy spectrum and composition of primary cosmic rays in the energy range of 1016 to 1018 eV. In this paper an overview of the KASCADE-Grande experiment and recent results will be presented.

Studies of Avalanche Photodiodes (APDS) as Readout Devices for Scintillating Fibers for High Energy Gamma-Ray Astronomy Telescopes

NASA Technical Reports Server (NTRS)

Vasile, Stefan; Shera, Suzanne; Shamo, Denis

1998-01-01

New gamma ray and charged particle telescope designs based on scintillating fiber arrays could provide low cost, high resolution, lightweight, very large area and multi radiation length instrumentation for planned NASA space exploration. The scintillating fibers low visible light output requires readout sensors with single photon detection sensitivity and low noise. The sensitivity of silicon Avalanche Photodiodes (APDS) matches well the spectral output of the scintillating fibers. Moreover, APDs have demonstrated single photon capability. The global aim of our work is to make available to NASA a novel optical detector concept to be used as scintillating fiber readouts and meeting the requirements of the new generations of space-borne gamma ray telescopes. We proposed to evaluate the feasibility of using RMD's small area APDs ((mu)APD) as scintillating fiber readouts and to study possible alternative (mu)APD array configurations for space borne readout scintillating fiber systems, requiring several hundred thousand to one million channels. The evaluation has been conducted in accordance with the task description and technical specifications detailed in the NASA solicitation "Studies of Avalanche Photodiodes (APD as readout devices for scintillating fibers for High Energy Gamma-Ray Astronomy Telescopes" (#8-W-7-ES-13672NAIS) posted on October 23, 1997. The feasibility study we propose builds on recent developments of silicon APD arrays and light concentrators advances at RMD, Inc. and on more than 5 years of expertise in scintillating fiber detectors. In a previous program we carried out the initial research to develop a high resolution, small pixel, solid-state, silicon APD array which exhibited very high sensitivity in the UV-VIS spectrum. This (mu)APD array is operated in Geiger mode and results in high gain (greater than 10(exp 8)), extremely low noise, single photon detection capability, low quiescent power (less than 10 (mu)W/pixel for 30 micrometers sensitive area diameter) and output in the 1-5 volt range. If successful, this feasibility study will make possible the development of a scintillating fiber detector with unsurpassed sensitivity, extremely low power usage, a crucial factor of merit for space based sensors and telescopes.

Reflectivity quenching of ESR multilayer polymer film reflector in optically bonded scintillator arrays

NASA Astrophysics Data System (ADS)

Loignon-Houle, Francis; Pepin, Catherine M.; Charlebois, Serge A.; Lecomte, Roger

2017-04-01

The 3M-ESR multilayer polymer film is a widely used reflector in scintillation detector arrays. As specified in the datasheet and confirmed experimentally by measurements in air, it is highly reflective (> 98 %) over the entire visible spectrum (400-1000 nm) for all angles of incidence. Despite these outstanding characteristics, it was previously found that light crosstalk between pixels in a bonded LYSO scintillator array with ESR reflector can be as high as ∼30-35%. This unexplained light crosstalk motivated further investigation of ESR optical performance. Analytical simulation of a multilayer structure emulating the ESR reflector showed that the film becomes highly transparent to incident light at large angles when surrounded on both sides by materials of refractive index higher than air. Monte Carlo simulations indicate that a considerable fraction (∼25-35%) of scintillation photons are incident at these leaking angles in high aspect ratio LYSO scintillation crystals. The film transparency was investigated experimentally by measuring the scintillation light transmission through the ESR film sandwiched between a scintillation crystal and a photodetector with or without layers of silicone grease. Strong light leakage, up to nearly 30%, was measured through the reflector when coated on both sides with silicone, thus elucidating the major cause of light crosstalk in bonded arrays. The reflector transparency was confirmed experimentally for angles of incidence larger than 60 ° using a custom designed setup allowing illumination of the bonded ESR film at selected grazing angles. The unsuspected ESR film transparency can be beneficial for detector arrays exploiting light sharing schemes, but it is highly detrimental for scintillator arrays designed for individual pixel readout.

Investigation of Very Fast Light Detectors: Silicon Photomultiplier and Micro PMT for a Cosmic Ray Array

NASA Astrophysics Data System (ADS)

Cervantes, Omar; Reyes, Liliana; Hooks, Tyler; Perez, Luis; Ritt, Stefan

2016-03-01

To construct a cosmic detector array using 4 scintillation detectors, we investigated 2 recent light sensor technologies from Hamamatsu, as possible readout detectors. First, we investigated several homemade versions of the multipixel photon counter (MPPC) light sensors. These detectors were either biased with internal or external high voltage power supplies. We made extensive measurements to confirm for the coincidence of the MPPC devices. Each sensor is coupled to a wavelength shifting fiber (WSF) that is embedded along a plastic scintillator sheet (30cmx60cmx1/4''). Using energetic cosmic rays, we evaluated several of these homemade detector modules placed above one another in a light proof enclosure. Next, we assembled 2 miniaturized micro photomultiplier (micro PMT), a device recently marketed by Hamamatsu. These sensors showed very fast response times. With 3 WSF embedded in scintillator sheets, we performed coincidence experiments. The detector waveforms were captured using the 5GS/sec domino ring sampler, the DRS4 and our workflow using the CERN PAW package and data analysis results would be presented. Title V Grant.

Safeguards Technology Development Program 1st Quarter FY 2018 Report

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

Prasad, Manoj K.

LLNL will evaluate the performance of a stilbene-based scintillation detector array for IAEA neutron multiplicity counting (NMC) applications. This effort will combine newly developed modeling methodologies and recently acquired high-efficiency stilbene detector units to quantitatively compare the prototype system performance with the conventional He-3 counters and liquid scintillator alternatives.

A novel phoswich imaging detector for simultaneous beta and coincidence-gamma imaging of plant leaves.

PubMed

Wu, Heyu; Tai, Yuan-Chuan

2011-09-07

To meet the growing demand for functional imaging technology for use in studying plant biology, we are developing a novel technique that permits simultaneous imaging of escaped positrons and coincidence gammas from annihilation of positrons within an intake leaf. The multi-modality imaging system will include two planar detectors: one is a typical PET detector array and the other is a phoswich imaging detector that detects both beta and gamma. The novel phoswich detector is made of a plastic scintillator, a lutetium oxyorthosilicate (LSO) array, and a position sensitive photomultiplier tube (PS-PMT). The plastic scintillator serves as a beta detector, while the LSO array serves as a gamma detector and light guide that couples scintillation light from the plastic detector to the PMT. In our prototype, the PMT signal was fed into the Siemens QuickSilver electronics to achieve shaping and waveform sampling. Pulse-shape discrimination based on the detectors' decay times (2.1 ns for plastic and 40 ns for LSO) was used to differentiate beta and gamma events using the common PMT signals. Using our prototype phoswich detector, we simultaneously measured a beta image and gamma events (in single mode). The beta image showed a resolution of 1.6 mm full-width-at-half-maximum using F-18 line sources. Because this shows promise for plant-scale imaging, our future plans include development of a fully functional simultaneous beta-and-coincidence-gamma imager with sub-millimeter resolution imaging capability for both modalities.

Conceptual design and optimization of a plastic scintillator array for 2D tomography using a compact D-D fast neutron generator.

PubMed

Adams, Robert; Zboray, Robert; Cortesi, Marco; Prasser, Horst-Michael

2014-04-01

A conceptual design optimization of a fast neutron tomography system was performed. The system is based on a compact deuterium-deuterium fast neutron generator and an arc-shaped array of individual neutron detectors. The array functions as a position sensitive one-dimensional detector allowing tomographic reconstruction of a two-dimensional cross section of an object up to 10 cm across. Each individual detector is to be optically isolated and consists of a plastic scintillator and a Silicon Photomultiplier for measuring light produced by recoil protons. A deterministic geometry-based model and a series of Monte Carlo simulations were used to optimize the design geometry parameters affecting the reconstructed image resolution. From this, it is expected that with an array of 100 detectors a reconstructed image resolution of ~1.5mm can be obtained. Other simulations were performed in order to optimize the scintillator depth (length along the neutron path) such that the best ratio of direct to scattered neutron counts is achieved. This resulted in a depth of 6-8 cm and an expected detection efficiency of 33-37%. Based on current operational capabilities of a prototype neutron generator being developed at the Paul Scherrer Institute, planned implementation of this detector array design should allow reconstructed tomograms to be obtained with exposure times on the order of a few hours. Copyright © 2014 Elsevier Ltd. All rights reserved.

Optimizing the Timing Resolution for the NEXT Array

NASA Astrophysics Data System (ADS)

Engelhardt, A.; Shadrick, S.; Rajabali, M.; Schmitt, K.; Grzywacz, R.

2016-09-01

In nuclear physics studies there are very few detectors capable of measuring neutron energies in the 0.1-10 MeV energy range with a reasonable resolution. The VANDLE array is the premier detector array for these measurements, yet VANDLE is limited by the its thickness (2.9 cm minimum).The Neutron dEtector with Tracking (NEXT) array would be capable of surpassing the limitations caused by the large size of VANDLE bars. A proposed configuration of each neutron detector consists of ten 3-mm thick plastic scintillators with two or more silicon photomultipliers (SiPMs) attached at each end. To achieve the desired energy resolution for neutron energy measurements through time of flight, the timing resolution between these SiPMs needs to be below 200 ps. A SiPM was placed on each end of a plastic scintillator inside a light-tight electrical box along with a 137Cs source. An analog circuit was designed in order to measure the timing difference between the two SiPMs. Different configurations of SiPM sizes, scintillator sizes, and wrappings were tested in order to determine the configuration that yields the best timing resolution. Details of the testing procedures and results will be presented. Research Supported by the National Nuclear Security Administration.

Performance of the Versatile Array of Neutron Detectors at Low Energy (VANDLE)

DOE PAGES

Peters, W. A.; Ilyushkin, S.; Madurga, M.; ...

2016-08-26

The Versatile Array of Neutron Detectors at Low Energy (VANDLE) is a new, highly efficient plastic-scintillator array constructed for decay and transfer reaction experimental setups that require neutron detection. The versatile and modular design allows for customizable experimental setups including beta-delayed neutron spectroscopy and (d,n) transfer reactions in normal and inverse kinematics. The neutron energy and prompt-photon discrimination is determined through the time of flight technique. Fully digital data acquisition electronics and integrated triggering logic enables some VANDLE modules to achieve an intrinsic efficiency over 70% for 300-keV neutrons, measured through two different methods. A custom Geant4 simulation models aspectsmore » of the detector array and the experimental setups to determine efficiency and detector response. Lastly, a low detection threshold, due to the trigger logic and digitizing data acquisition, allowed us to measure the light-yield response curve from elastically scattered carbon nuclei inside the scintillating plastic from incident neutrons with kinetic energies below 2 MeV.« less

DESCANT--The DEuterated SCintillator Array for Neutron Tagging

NASA Astrophysics Data System (ADS)

Bildstein, Vinzenz; Garrett, P. E.; Bandyopadhay, D.; Bangay, J.; Bianco, L.; Demand, G.; Hadinia, B.; Leach, K. G.; Sumithrarachchi, C.; Wong, J.; Ashley, S. F.; Crider, B. P.; McEllistrem, M. T.; Peters, E. E.; Prados-Estévez, F. M.; Yates, S. W.; Vanhoy, J. R.; Ball, G. C.; Garnsworthy, A. B.; Hackman, G.; Pearson, C. J.; Sarazin, F.

2014-09-01

The DESCANT array at TRIUMF is designed to track neutrons from RIB experiments. DESCANT is composed of 70 close-packed deuterated organic liquid scintillators coupled to digital fast read-out ADC modules. This configuration will permit online pulse-shape discrimination between neutron and γ-ray events. The anisotropy of the n - d scattering will allow distinction of higher neutron multiplicities from scattering within the array and determination of the neutron energy spectrum directly from the pulse-height spectrum without using TOF. A prototype detector has been tested with monoenergetic neutrons at the accelerator laboratory of the University of Kentucky and a 24Mg(3He, n)26Si experiment has been performed with eight DESCANT detectors and two HPGe detectors. The results of the tests and the status of DESCANT will be presented.

Applications of LaBr3(Ce) Gamma-ray Spectrometer Arrays for Nuclear Spectroscopy and Radionuclide Assay

NASA Astrophysics Data System (ADS)

Regan, PH; Shearman, R.; Daniel, T.; Lorusso, G.; Collins, SM; Judge, SM; Bell; Pearce, AK; Gurgi, LA; Rudigier, M.; Podolyák, Zs; Mărginean, N.; Mărginean, R.; Kisyov, S.

2016-10-01

An overview of the use of discrete energy gamma-ray detectors based on cerium- doped LaBr3 scintillators for use in nuclear spectroscopy is presented. This review includes recent applications of such detectors in mixed, 'hybrid' gamma-ray coincidence detection arrays such ROSPHERE at IFIN-HH, Bucharest; EXILL+FATIMA at ILL Grenoble, France; GAMMASPHERE+FATIMA at Argonne National Laboratory, USA; FATIMA + EURICA, at RIKEN, Japan; and the National Nuclear Array (NANA) at the UK's National Physical Laboratory. This conference paper highlights the capabilities and limitations of using these sub-nanosecond 'fast-timing', medium-resolution gamma-ray detectors for both nuclear structure research and radionuclide standardisation. Potential future application of such coincidence scintillator arrays in measurements of civilian nuclear fuel waste evaluation and assay is demonstrated using coincidence spectroscopy of a mixed 134,7Cs source.

Optimization, evaluation and calibration of a cross-strip DOI detector

NASA Astrophysics Data System (ADS)

Schmidt, F. P.; Kolb, A.; Pichler, B. J.

2018-02-01

This study depicts the evaluation of a SiPM detector with depth of interaction (DOI) capability via a dual-sided readout that is suitable for high-resolution positron emission tomography and magnetic resonance (PET/MR) imaging. Two different 12  ×  12 pixelated LSO scintillator arrays with a crystal pitch of 1.60 mm are examined. One array is 20 mm-long with a crystal separation by the specular reflector Vikuiti enhanced specular reflector (ESR), and the other one is 18 mm-long and separated by the diffuse reflector Lumirror E60 (E60). An improvement in energy resolution from 22.6% to 15.5% for the scintillator array with the E60 reflector is achieved by taking a nonlinear light collection correction into account. The results are FWHM energy resolutions of 14.0% and 15.5%, average FWHM DOI resolutions of 2.96 mm and 1.83 mm, and FWHM coincidence resolving times of 1.09 ns and 1.48 ns for the scintillator array with the ESR and that with the E60 reflector, respectively. The measured DOI signal ratios need to be assigned to an interaction depth inside the scintillator crystal. A linear and a nonlinear method, using the intrinsic scintillator radiation from lutetium, are implemented for an easy to apply calibration and are compared to the conventional method, which exploits a setup with an externally collimated radiation beam. The deviation between the DOI functions of the linear or nonlinear method and the conventional method is determined. The resulting average of differences in DOI positions is 0.67 mm and 0.45 mm for the nonlinear calibration method for the scintillator array with the ESR and with the E60 reflector, respectively; Whereas the linear calibration method results in 0.51 mm and 0.32 mm for the scintillator array with the ESR and the E60 reflector, respectively; and is, due to its simplicity, also applicable in assembled detector systems.

Optimization, evaluation and calibration of a cross-strip DOI detector.

PubMed

Schmidt, F P; Kolb, A; Pichler, B J

2018-02-20

This study depicts the evaluation of a SiPM detector with depth of interaction (DOI) capability via a dual-sided readout that is suitable for high-resolution positron emission tomography and magnetic resonance (PET/MR) imaging. Two different 12  ×  12 pixelated LSO scintillator arrays with a crystal pitch of 1.60 mm are examined. One array is 20 mm-long with a crystal separation by the specular reflector Vikuiti enhanced specular reflector (ESR), and the other one is 18 mm-long and separated by the diffuse reflector Lumirror E60 (E60). An improvement in energy resolution from 22.6% to 15.5% for the scintillator array with the E60 reflector is achieved by taking a nonlinear light collection correction into account. The results are FWHM energy resolutions of 14.0% and 15.5%, average FWHM DOI resolutions of 2.96 mm and 1.83 mm, and FWHM coincidence resolving times of 1.09 ns and 1.48 ns for the scintillator array with the ESR and that with the E60 reflector, respectively. The measured DOI signal ratios need to be assigned to an interaction depth inside the scintillator crystal. A linear and a nonlinear method, using the intrinsic scintillator radiation from lutetium, are implemented for an easy to apply calibration and are compared to the conventional method, which exploits a setup with an externally collimated radiation beam. The deviation between the DOI functions of the linear or nonlinear method and the conventional method is determined. The resulting average of differences in DOI positions is 0.67 mm and 0.45 mm for the nonlinear calibration method for the scintillator array with the ESR and with the E60 reflector, respectively; Whereas the linear calibration method results in 0.51 mm and 0.32 mm for the scintillator array with the ESR and the E60 reflector, respectively; and is, due to its simplicity, also applicable in assembled detector systems.

Depth of interaction determination in monolithic scintillator with double side SiPM readout.

PubMed

Morrocchi, Matteo; Ambrosi, Giovanni; Bisogni, Maria Giuseppina; Bosi, Filippo; Boretto, Marco; Cerello, Piergiorgio; Ionica, Maria; Liu, Ben; Pennazio, Francesco; Piliero, Maria Antonietta; Pirrone, Giovanni; Postolache, Vasile; Wheadon, Richard; Del Guerra, Alberto

2017-12-01

Monolithic scintillators read out by arrays of photodetectors represent a promising solution to obtain high spatial resolution and the depth of interaction (DOI) of the annihilation photon. We have recently investigated a detector geometry composed of a monolithic scintillator readout on two sides by silicon photomultiplier (SiPM) arrays, and we have proposed two parameters for the DOI determination: the difference in the number of triggered SiPMs on the two sides of the detector and the difference in the maximum collected signal on a single SiPM on each side. This work is focused on the DOI calibration and on the determination of the capability of our detector. For the DOI calibration, we studied a method which can be implemented also in detectors mounted in a full PET scanner. We used a PET detector module composed of a monolithic 20 × 20 × 10 mm 3 LYSO scintillator crystal coupled on two opposite faces to two arrays of SiPMs. On each side, the scintillator was coupled to 6 × 6 SiPMs. In this paper, the two parameters previously proposed for the DOI determination were calibrated with two different methods. The first used a lateral scan of the detector with a collimated 511 keV pencil beam at steps of 0.5 mm to study the detector DOI capability, while the second used the background radiation of the 176 Lu in the scintillator. The DOI determination capability was tested on different regions of the detector using each parameter and the combination of the two. With both parameters for the DOI determination, in the lateral scan, the bias between the mean reconstructed DOI and the real beam position was lower than 0.3 mm, and the DOI distribution had a standard deviation of about 1.5 mm. When using the calibration with the radioactivity of the LYSO, the mean bias increased of about 0.2 mm but with no degradation of the standard deviation of the DOI distribution. The two parameters allow to achieve a DOI resolution comparable with the state of the art, giving a continuous information about the three-dimensional interaction position of the scintillation. These results were obtained by using simple estimators and a detector scalable to a whole PET system. The DOI calibration obtained using lutetium natural radioactivity gives results comparable to the other standard method but appears more readily applicable to detectors mounted in a full PET scanner.

Probing Cherenkov and Scintillation Light Separation for Next-Generation Neutrino Detectors

NASA Astrophysics Data System (ADS)

Caravaca, J.; Descamps, F. B.; Land, B. J.; Orebi Gann, G. D.; Wallig, J.; Yeh, M.

2017-09-01

The ability to separate Cherenkov and scintillation signals in liquid scintillator detectors would enable outstanding background rejection for next-generation neutrino experiments. Reconstruction of directional information, ring imaging, and sub-Cherenkov threshold detection all have the potential to substantially improve particle and event identification. The Cherenkov-Scintillation Separation (CHESS) experiment uses an array of small, fast photomultipliers (PMTs) and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in a scintillation medium based on photon hit times and detected charge. This setup has been used to characterize the ability to detect Cherenkov light in a range of target media. We show results with pure organic scintillator (LAB) and the prospects with scintillators with a secondary fluor (LAB/PPO). There are future plans to deploy the newly developed water-based liquid scintillator, a medium with a higher Cherenkov/Scintillation light yield ratio than conventional pure liquid scintillators, enhancing the visibility of the less abundant Cherenkov light in the presence of scintillation light. These results can inform the development of future large-scale detectors, such as the proposed Theia experiment, or other large detectors at underground laboratories such as the far-site of the new Long Baseline Neutrino Facility at the Sanford Underground Research Facility. CHESS detector calibrations and commissioning will be discussed, and the latest results will be presented.

TU-E-BRA-05: Reverse Geometry Imaging with MV Detector for Improved Image Resolution.

PubMed

Ganguly, A; Abel, E; Sun, M; Fahrig, R; Virshup, G; Star-Lack, J

2012-06-01

Thick pixilated scintillators can offer significant improvements in quantum efficiency over phosphor screen megavoltage (MV) detectors. However spatial resolution can be compromised due to the spreading of light across pixels within septa. Of particular interest are the lower energy x-ray photons and associated light photons that produce higher image contrast but are stopped near the scintillator entrance surface. They suffer the most scattering in the scintillator prior to detection in the photodiodes. Reversing the detector geometry, so that the incident x-ray beam passes through the photodiode array into the scintillator, allows the light to scatter less prior to detection. This also reduces the Swank noise since now higher and lower energy x-ray photons tend to produce similar electronic signals. In this work, we present simulations and measurements of detector MTF for the conventional/forward and reverse geometries to demonstrate this phenomenon. A tabletop system consisting of a Varian CX1 1MeV linear accelerator and a modified Varian Paxscan4030 with the readout electronics moved away from the incident the beam was used. A special holder was used to press a 2.5W×5.0L×2.0Hcm 3 pixellated Cesium Iodide (CsI:Tl) scintillator array on to the detector glass. The CsI array had a pitch of 0.784mm with plastic septa between pixels and the photodiode array pitch was 0.192 mm. The MTF in the forward and reverse geometries was measured using a 0.5mm thick Tantalum slanted edge. Geant4-based Monte Carlo simulations were performed for comparison. The measured and simulated MTFs matched to within 3.4(±3.7)% in the forward and 4.4(±1.5)% in reverse geometries. The reverse geometry MTF was higher than the forward geometry MTF at all spatial frequencies and doubled to .25 at 0.3lp/mm. A novel method of improving the image resolution at MV energies was demonstrated. The improvements should be more pronounced with increased scintillator thickness. Funding support provided by NIH (grant number NIH R01 CA138426). © 2012 American Association of Physicists in Medicine.

High resolution scintillation detector with semiconductor readout

DOEpatents

Levin, Craig S.; Hoffman, Edward J.

2000-01-01

A novel high resolution scintillation detector array for use in radiation imaging such as high resolution Positron Emission Tomography (PET) which comprises one or more parallelepiped crystals with at least one long surface of each crystal being in intimate contact with a semiconductor photodetector such that photons generated within each crystal by gamma radiation passing therethrough is detected by the photodetector paired therewith.

Arrays of Segmented, Tapered Light Guides for Use With Large, Planar Scintillation Detectors

NASA Astrophysics Data System (ADS)

Raylman, Raymond R.; Vaigneur, Keith; Stolin, Alexander V.; Jaliparthi, Gangadhar

2015-06-01

Metabolic imaging techniques can potentially improve detection and diagnosis of cancer in women with radiodense and/or fibrocystic breasts. Our group has previously developed a high-resolution positron emission tomography imaging and biopsy device (PEM-PET) to detect and guide the biopsy of suspicious breast lesions. Initial testing revealed that the imaging field-of-view (FOV) of the scanner was smaller than the physical size of the detector's active area, which could hinder sampling of breast areas close to the chest wall. The purpose of this work was to utilize segmented, tapered light guides for optically coupling the scintillator arrays to arrays of position-sensitive photomultipliers to increase both the active FOV and identification of individual scintillator elements. Testing of the new system revealed that the optics of these structures made it possible to discern detector elements from the complete active area of the detector face. In the previous system the top and bottom rows and left and right columns were not identifiable. Additionally, use of the new light guides increased the contrast of individual detector elements by up to 129%. Improved element identification led to a spatial resolution increase by approximately 12%. Due to attenuation of light in the light guides the detector energy resolution decreased from 18.5% to 19.1%. Overall, these improvements should increase the field-of-view and spatial resolution of the dedicated breast-PET system.

Performance comparison of MoNA and LISA neutron detectors

NASA Astrophysics Data System (ADS)

Purtell, Kimberly; Rethman, Kaitlynne; Haagsma, Autumn; Finck, Joseph; Smith, Jenna; Snyder, Jesse

2010-11-01

In 2002 eight primarily undergraduate institutions constructed and tested the Modular Neutron Array (MoNA) which has been used to detect high energy neutrons at the National Superconducting Cyclotron Laboratory (NSCL). Nine institutions have now designed, constructed and tested the Large-area multi-Institutional Scintillator Array (LISA) neutron detector which will be used at the NSCL and the future Facility for Rare Isotope Beams (FRIB). Both detectors are comprised of 144 detector modules. Each module is a 200 x 10 x 10 cm^3 bar organic plastic scintillator with a photomultiplier tube mounted on each end. Using cosmic rays and a gamma source, we compared the performance of MoNA and LISA by using the same electronics to check light attenuation, position resolution, rise times, and cosmic ray peak widths. Results will be presented.

Junction-side illuminated silicon detector arrays

DOEpatents

Iwanczyk, Jan S.; Patt, Bradley E.; Tull, Carolyn

2004-03-30

A junction-side illuminated detector array of pixelated detectors is constructed on a silicon wafer. A junction contact on the front-side may cover the whole detector array, and may be used as an entrance window for light, x-ray, gamma ray and/or other particles. The back-side has an array of individual ohmic contact pixels. Each of the ohmic contact pixels on the back-side may be surrounded by a grid or a ring of junction separation implants. Effective pixel size may be changed by separately biasing different sections of the grid. A scintillator may be coupled directly to the entrance window while readout electronics may be coupled directly to the ohmic contact pixels. The detector array may be used as a radiation hardened detector for high-energy physics research or as avalanche imaging arrays.

Study of n- γ discrimination by zero-crossing method with SiPM based scintillation detectors

NASA Astrophysics Data System (ADS)

Grodzicka-Kobylka, M.; Szczesniak, T.; Moszyński, M.; Swiderski, L.; Wolski, D.; Baszak, J.; Korolczuk, S.; Schotanus, P.

2018-03-01

The paper presents a study of n / γ discrimination with 4x4 ch and 8x8 ch Multi Pixel Photon Counter (MPPC) arrays in neutron detectors based on Stilbene and EJ299-33 plastic scintillators. The n / γ discrimination showed an excellent capability of the MPPC arrays, comparable to that observed earlier with the classical PMTs. Particularly, an application of a zero-crossing method of n - γ discrimination prevented deterioration of the discrimination by the slow response of the Silicon Photomultiplier (SiPM, or MPPC interchangeably) array related to its large capacitance. It was confirmed by a good agreement of the Figure of Merit normalized to the number of photoelectrons determined for the MPPC arrays and XP5500 PMT.

Semiconductor radiation detector with internal gain

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

Iwanczyk, Jan; Patt, Bradley E.; Vilkelis, Gintas

An avalanche drift photodetector (ADP) incorporates extremely low capacitance of a silicon drift photodetector (SDP) and internal gain that mitigates the surface leakage current noise of an avalanche photodetector (APD). The ADP can be coupled with scintillators such as CsI(Tl), NaI(Tl), LSO or others to form large volume scintillation type gamma ray detectors for gamma ray spectroscopy, photon counting, gamma ray counting, etc. Arrays of the ADPs can be used to replace the photomultiplier tubes (PMTs) used in conjunction with scintillation crystals in conventional gamma cameras for nuclear medical imaging.

A flexible scintillation light apparatus for rare events searches

NASA Astrophysics Data System (ADS)

Gironi, L.; Baldazzi, G.; Bonvicini, V.; Campana, R.; Capelli, S.; Evangelista, Y.; Fasoli, M.; Feroci, M.; Fuschino, F.; Labanti, C.; Marisaldi, M.; Previtali, E.; Riganese, L.; Rashevsky, A.; Sisti, M.; Vacchi, A.; Vedda, A.; Zampa, G.; Zampa, N.; Zuffa, M.

2016-05-01

FLARES (a Flexible scintillation Light Apparatus for Rare Event Searches) is a project for an innovative detector technology to be applied to rare event searches, and in particular to neutrinoless double beta decay experiments. Its novelty is the enhancement and optimization of the collection of the scintillation light emitted by ultra-pure crystals through the use of arrays of high performance silicon photodetectors cooled to 120 K. This would provide scintillation detectors with ~1% level energy resolution, with the advantages of a technology offering relatively simple low cost mass scalability and powerful background reduction handles, as requested by future neutrinoless double beta decay experimental programs.

A phoswich detector design for improved spatial sampling in PET

NASA Astrophysics Data System (ADS)

Thiessen, Jonathan D.; Koschan, Merry A.; Melcher, Charles L.; Meng, Fang; Schellenberg, Graham; Goertzen, Andrew L.

2018-02-01

Block detector designs, utilizing a pixelated scintillator array coupled to a photosensor array in a light-sharing design, are commonly used for positron emission tomography (PET) imaging applications. In practice, the spatial sampling of these designs is limited by the crystal pitch, which must be large enough for individual crystals to be resolved in the detector flood image. Replacing the conventional 2D scintillator array with an array of phoswich elements, each consisting of an optically coupled side-by-side scintillator pair, may improve spatial sampling in one direction of the array without requiring resolving smaller crystal elements. To test the feasibility of this design, a 4 × 4 phoswich array was constructed, with each phoswich element consisting of two optically coupled, 3 . 17 × 1 . 58 × 10mm3 LSO crystals co-doped with cerium and calcium. The amount of calcium doping was varied to create a 'fast' LSO crystal with decay time of 32.9 ns and a 'slow' LSO crystal with decay time of 41.2 ns. Using a Hamamatsu R8900U-00-C12 position-sensitive photomultiplier tube (PS-PMT) and a CAEN V1720 250 MS/s waveform digitizer, we were able to show effective discrimination of the fast and slow LSO crystals in the phoswich array. Although a side-by-side phoswich array is feasible, reflections at the crystal boundary due to a mismatch between the refractive index of the optical adhesive (n = 1 . 5) and LSO (n = 1 . 82) caused it to behave optically as an 8 × 4 array rather than a 4 × 4 array. Direct coupling of each phoswich element to individual photodetector elements may be necessary with the current phoswich array design. Alternatively, in order to implement this phoswich design with a conventional light sharing PET block detector, a high refractive index optical adhesive is necessary to closely match the refractive index of LSO.

Performance of Gas Scintillation Proportional Counter Array for High-Energy X-Ray Observatory

NASA Technical Reports Server (NTRS)

Gubarev, Mikhail; Ramsey, Brian; Apple, Jeffery

2004-01-01

A focal plane array of high-pressure gas scintillation proportional counters (GSPC) for a High Energy X-Ray Observatory (HERO) is developed at the Marshall Space Flight Center. The array is consisted from eight GSPCs and is a part of balloon born payload scheduled to flight in May 2004. These detectors have an active area of approximately 20 square centimeters, and are filled with a high pressure (10(exp 6) Pa) xenon-helium mixture. Imaging is via crossed-grid position-sensitive phototubes sensitive in the UV region. The performance of the GSPC is well matched to that of the telescopes x-ray optics which have response to 75 keV and a focal spot size of approximately 500 microns. The detector's energy resolution, 4% FWHM at 60 keV, is adequate for resolving the broad spectral lines of astrophysical importance and for accurate continuum measurements. Results of the on-earth detector calibration will be presented and in-flight detector performance will be provided, as available.

Novel laser-processed CsI:Tl detector for SPECT

PubMed Central

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

2016-01-01

Purpose: The aim of this work is to demonstrate the feasibility of a novel technique for fabrication of high spatial resolution CsI:Tl scintillation detectors for single photon emission computed tomography systems. Methods: The scintillators are fabricated using laser-induced optical barriers technique to create optical microstructures (or optical barriers) inside the CsI:Tl crystal bulk. The laser-processed CsI:Tl crystals are 3, 5, and 10 mm in thickness. In this work, the authors focus on the simplest pattern of optical barriers in that the barriers are created in the crystal bulk to form pixel-like patterns resembling mechanically pixelated scintillators. The monolithic CsI:Tl scintillator samples are fabricated with optical barrier patterns with 1.0 × 1.0 mm2 and 0.625 × 0.625 mm2 pixels. Experiments were conducted to characterize the fabricated arrays in terms of pixel separation and energy resolution. A 4 × 4 array of multipixel photon counter was used to collect the scintillation light in all the experiments. Results: The process yield for fabricating the CsI:Tl arrays is 100% with processing time under 50 min. From the flood maps of the fabricated detectors exposed to 122 keV gammas, peak-to-valley (P/V) ratios of greater than 2.3 are calculated. The P/V values suggest that regardless of the crystal thickness, the pixels can be resolved. Conclusions: The results suggest that optical barriers can be considered as a robust alternative to mechanically pixelated arrays and can provide high spatial resolution while maintaining the sensitivity in a high-throughput and cost-effective manner. PMID:27147372

High Resolution PET with 250 micrometer LSO Detectors and Adaptive Zoom

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

Cherry, Simon R.; Qi, Jinyi

2012-01-08

There have been impressive improvements in the performance of small-animal positron emission tomography (PET) systems since their first development in the mid 1990s, both in terms of spatial resolution and sensitivity, which have directly contributed to the increasing adoption of this technology for a wide range of biomedical applications. Nonetheless, current systems still are largely dominated by the size of the scintillator elements used in the detector. Our research predicts that developing scintillator arrays with an element size of 250 {micro}m or smaller will lead to an image resolution of 500 {micro}m when using 18F- or 64Cu-labeled radiotracers, giving amore » factor of 4-8 improvement in volumetric resolution over the highest resolution research systems currently in existence. This proposal had two main objectives: (i) To develop and evaluate much higher resolution and efficiency scintillator arrays that can be used in the future as the basis for detectors in a small-animal PET scanner where the spatial resolution is dominated by decay and interaction physics rather than detector size. (ii) To optimize one such high resolution, high sensitivity detector and adaptively integrate it into the existing microPET II small animal PET scanner as a 'zoom-in' detector that provides higher spatial resolution and sensitivity in a limited region close to the detector face. The knowledge gained from this project will provide valuable information for building future PET systems with a complete ring of very high-resolution detector arrays and also lay the foundations for utilizing high-resolution detectors in combination with existing PET systems for localized high-resolution imaging.« less

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 semiconductor P-N detectors such as P-NiO:Li, N-SnO2 :F for gamma detection could be possibly applicable for design of a one dimension array configuration with suitable spatial resolution of 2.7 mm for nuclear medicine imaging.

Design and characterization of a small muon tomography system

NASA Astrophysics Data System (ADS)

Jo, Woo Jin; An, Su Jung; Kim, Hyun-Il; Lee, Chae Young; Chung, Heejun; Chung, Yong Hyun

2015-02-01

Muon tomography is a useful method for monitoring special nuclear materials (SNMs) because it can provide effective information on the presence of high-Z materials, has a high enough energy to deeply penetrate large amounts of shielding, and does not lead to any health risks and danger above background. We developed a 2-D muon detector and designed a muon tomography system employing four detector modules. Two top and two bottom detectors are, respectively, employed to record the incident and the scattered muon trajectories. The detector module for the muon tomography system consists of a plastic scintillator, wavelength-shifting (WLS) fiber arrays placed orthogonally on the top and the bottom of the scintillator, and a position-sensitive photomultiplier (PSPMT). The WLS fiber arrays absorb light photons emitted by the plastic scintillator and re-emit green lights guided to the PSPMT. The light distribution among the WLS fiber arrays determines the position of the muon interaction; consequently, 3-D tomographic images can be obtained by extracting the crossing points of the individual muon trajectories by using a point-of-closest-approach algorithm. The goal of this study is to optimize the design parameters of a muon tomography system by using the Geant4 code and to experimentally evaluate the performance of the prototype detector. Images obtained by the prototype detector with a 420-nm laser light source showed good agreement with the simulation results. This indicates that the proposed detector is feasible for use in a muon tomography system and can be used to verify the Z-discrimination capability of the muon tomography system.

SU-E-T-167: Characterization of In-House Plastic Scintillator Detectors Array for Radiation Therapy

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

Zhu, T; Liu, H; Dimofte, A

Purpose: To characterize basic performance of plastic scintillator detectors (PSD) array designed for dosimetry of radiation therapy. Methods: An in-house PSD array has been developed by placing single point PSD into customized 2D holder. Each point PSD is a plastic scintillating fiber-based detector designed for highly accurate measurement of small radiotherapy fields used in patient plan verification and machine commissioning and QA procedures. A parallel fiber without PSD is used for Cerenkov separation by subtracting from PSD readings. Cerenkov separation was confirmed by optical spectroscopy. Alternative Cerenkov separation approaches are also investigated. The optical signal was converted to electronic signalmore » with a photodiode and then subsequently amplified. We measured its dosimetry performance, including percentage depth dose and output factor, and compared with reference ion chamber measurements. The PSD array is then placed along the radiation beam for multiple point dose measurement, representing subsets of PDD measurements, or perpendicular to the beam for profile measurements. Results: The dosimetry results of PSD point measurements agree well with reference ion chamber measurements. For percentage depth dose, the maximal differences between PSD and ion chamber results are 3.5% and 2.7% for 6MV and 15MV beams, respectively. For the output factors, PSD measurements are within 3% from ion chamber results. PDD and profile measurement with PSD array are also performed. Conclusions: The current design of multichannel PSD array is feasible for the dosimetry measurement in radiation therapy. Dose distribution along or perpendicular to the beam path could be measured. It might as well be used as range verification in proton therapy.A PS hollow fiber detector will be investigated to eliminate the Cerenkov radiation effect so that all 32 channels can be used.« less

Developing LAr Scintillation Light Collection Ideas in the Short Baseline Neutrino Detector

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

Szelc, A. M.

2016-02-08

Scintillation light is becoming the most rapidly developing feature of Liquid Argon Time Projection Chamber (LArTPC) neutrino detectors due to its capability to enhance and expand their physics reach traditionally based on charge readout. The SBND detector, set to be built on the Booster Neutrino Beam Line at Fermilab, is in a unique position to test novel liquid argon scintillation light readout systems in a detector with physics neutrino events. The different ideas under consideration by the collaboration are described, including an array of PMTs detecting direct light, SiPM coupled lightguide bars and a setup which uses PMTs/SiPMS and wavelengthmore » shifter covered reflector foils, as well as their respective strengths and physics foci and the benchmarks used to compare them.« less

Astroparticle Physics: Detectors for Cosmic Rays

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

Salazar, Humberto; Villasenor, Luis

2006-09-25

We describe the work that we have done over the last decade to design and construct instruments to measure properties of cosmic rays in Mexico. We describe the measurement of the muon lifetime and the ratio of positive to negative muons in the natural background of cosmic ray muons at 2000 m.a.s.l. Next we describe the detection of decaying and crossing muons in a water Cherenkov detector as well as a technique to separate isolated particles. We also describe the detection of isolated muons and electrons in a liquid scintillator detector and their separation. Next we describe the detection ofmore » extensive air showers (EAS) with a hybrid detector array consisting of water Cherenkov and liquid scintillator detectors, located at the campus of the University of Puebla. Finally we describe work in progress to detect EAS at 4600 m.a.s.l. with a water Cherenkov detector array and a fluorescence telescope at the Sierra Negra mountain.« less

Deuterated-xylene (xylene-d10; EJ301D): A new, improved deuterated liquid scintillator for neutron energy measurements without time-of-flight

NASA Astrophysics Data System (ADS)

Becchetti, F. D.; Raymond, R. S.; Torres-Isea, R. O.; Di Fulvio, A.; Clarke, S. D.; Pozzi, S. A.; Febbraro, M.

2016-06-01

In conjunction with Eljen Technology, Inc. (Sweetwater,TX) we have designed, constructed, and evaluated a 3 in. ×3 in. deuterated-xylene organic liquid scintillator (C8D10; EJ301D) as a fast neutron detector. Similar to deuterated benzene (C6D6; NE230, BC537, and EJ315) this scintillator can provide good pulse-shape discrimination between neutrons and gamma rays, has good timing characteristics, and can provide a light spectrum with peaks corresponding to discrete neutron energy groups up to ca. 20 MeV. Unlike benzene-based detectors, deuterated xylene is less volatile, less toxic, is not known to be carcinogenic, has a higher flashpoint, and hence is much safer for many applications. In addition EJ301D can provide slightly more light output and better PSD than deuterated-benzene scintillators. We show that, as with deuterated-benzene scintillators, the light-response spectra can be unfolded to provide useable neutron energy spectra without need for time-of-flight (ToF). An array of these detectors arranged at many angles close to a reaction target can be much more effective (×10 to ×100 or more) than an array of long-path ToF detectors which must utilize a narrowly-bunched and pulse-selected beam. As we demonstrate using a small Van de Graaff accelerator, measurements can thus be performed when a bunched and pulse-selected beam (as needed for time-of-flight) is not available.

First characterization of a digital SiPM based time-of-flight PET detector with 1 mm spatial resolution

NASA Astrophysics Data System (ADS)

Seifert, Stefan; van der Lei, Gerben; van Dam, Herman T.; Schaart, Dennis R.

2013-05-01

Monolithic scintillator detectors can offer a combination of spatial resolution, energy resolution, timing performance, depth-of-interaction information, and detection efficiency that make this type of detector a promising candidate for application in clinical, time-of-flight (TOF) positron emission tomography (PET). In such detectors the scintillation light is distributed over a relatively large number of photosensor pixels and the light intensity per pixel can be relatively low. Therefore, monolithic scintillator detectors are expected to benefit from the low readout noise offered by a novel photosensor called the digital silicon photomultiplier (dSiPM). Here, we present a first experimental characterization of a TOF PET detector comprising a 24 × 24 × 10 mm3 LSO:Ce,0.2%Ca scintillator read out by a dSiPM array (DPC-6400-44-22) developed by Philips Digital Photon Counting. A spatial resolution of ˜1 mm full-width-at-half-maximum (FWHM) averaged over the entire crystal was obtained (varying from just below 1 mm FWHM in the detector center to ˜1.2 mm FWHM close to the edges). Furthermore, the bias in the position estimation at the crystal edges that is typically found in monolithic scintillators is well below 1 mm even in the corners of the crystal.

Pulse-shape discrimination scintillators for homeland security applications

NASA Astrophysics Data System (ADS)

Ellis, Mark E.; Duroe, Kirk; Kendall, Paul A.

2016-09-01

An extensive programme of research has been conducted for scintillation liquids and plastics capable of neutron-gamma discrimination for deployment in future passive and active Homeland Security systems to provide protection against radiological and nuclear threats. The more established detection materials such as EJ-301 and EJ-309 are compared with novel materials such as EJ-299-33 and p-terphenyl. This research also explores the benefits that can be gained from improvements in the analogue-to-digital sampling rate and sample bit resolution. Results are presented on the Pulse Shape Discrimination performance of various detector and data acquisition combinations and how optimum configurations from these studies have been developed into field-ready detector arrays. Early results from application-specific experimental configurations of multi-element detector arrays are presented.

Development of a novel scintillation-trigger detector for the MTV experiment using aluminum-metallized film tapes

NASA Astrophysics Data System (ADS)

Tanaka, S.; Ozaki, S.; Sakamoto, Y.; Tanuma, R.; Yoshida, T.; Murata, J.

2014-07-01

A new type of a trigger-scintillation counter array designed for the MTV experiment at TRIUMF-ISAC has been developed, which uses aluminum-metallized film tape for wrapping to achieve the required assembling precision of ±0.5 mm. The MTV experiment uses a cylindrical drift chamber (CDC) as the main electron-tracking detector. The barrel-type trigger counter is placed inside the CDC to generate a trigger signal using 1 mm thick, 300 mm long thin plastic scintillation counters. Detection efficiency and light attenuation compared with conventional wrapping materials are studied.

Cherenkov and scintillation light separation on the CheSS experiment

NASA Astrophysics Data System (ADS)

Caravaca, Javier; Land, Benjamin; Descamps, Freija; Orebi Gann, Gabriel D.

2016-09-01

Separation of the scintillation and Cherenkov light produced in liquid scintillators enables outstanding capabilities for future particle detectors, the most relevant being: particle directionality information in a low energy threshold detector and improved particle identification. The CheSS experiment uses an array of small, fast photomultipliers (PMTs) and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in liquid scintillator using two techniques: based on the photon density and using the photon hit time information. A charged particle ionizing a scintillation medium produces a prompt Cherenkov cone and late isotropic scintillation light, typically delayed by several ns. The fast response of our PMTs and DAQ provides a precision well below the ns level, making possible the time separation. Furthermore, the usage of the new developed water-based liquid scintillators (WbLS) enhances the separation since it allows tuning of the Cherenkov/Scintillation ratio. Latest results on the separation for pure liquid scintillators and WbLS will be presented.

Development of high resolution phoswich depth-of-interaction block detectors utilizing Mg co-doped new scintillators

NASA Astrophysics Data System (ADS)

Kobayashi, Takahiro; Yamamoto, Seiichi; Yeom, Jung-Yeol; Kamada, Kei; Yoshikawa, Akira

2017-12-01

To correct for parallax error in positron emission tomography (PET), phoswich depth-of-interaction (DOI) detector using multiple scintillators with different decay times is a practical approach. However not many scintillator combinations suitable for phoswich DOI detector have been reported. Ce doped Gd3Ga3Al2O12 (GFAG) is a newly developed promising scintillator for PET detector, which has high density, high light output, appropriate light emission wavelength for silicon-photomultiplier (Si-PM) and faster decay time than that of Ce doped Gd3Al2Ga3O12 (GAGG). In this study, we developed a Si-PM based phoswich DOI block detector of GFAG with GAGG crystal arrays and evaluated its performance. We assembled a GFAG block and a GAGG block and they were optically coupled in depth direction to form a phoswich detector block. The phoswich block was optically coupled to a Si-PM array with a 1 mm thick light guide. The sizes of the GFAG and GAGG pixels were 0.9 mm x 0.9 mm x 7.5 mm and they were arranged into 24 x 24 matrix with 0.1 mm thick BaSO4 as reflector. We conducted the performance evaluation for two types of configurations; GFAG block arranged in upper layer (GFAG/GAGG) and GAGG arranged in upper layer (GAGG/GFAG). The measured two dimensional position histograms of these block detectors showed good separation and pulse shape spectra produced two distinct peaks for both configurations although some difference in energy spectra were observed. These results indicate phoswich block detectors composed of GFAG and GAGG are promising for high resolution DOI PET systems.

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

PubMed

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

2018-02-01

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

Clinical prototype of a plastic water-equivalent scintillating fiber dosimeter array for QA applications.

PubMed

Lacroix, Fréderic; Archambault, Louis; Gingras, Luc; Guillot, Mathieu; Beddar, A Sam; Beaulieu, Luc

2008-08-01

A clinical prototype of a scintillating fiber dosimeter array for quality assurance applications is presented. The array consists of a linear array of 29 plastic scintillation detectors embedded in a water-equivalent plastic sheet coupled to optical fibers used to guide optical photons to a charge coupled device (CCD) camera. The CCD is packaged in a light-tight, radiation-shielded housing designed for convenient transport. A custom designed connector is used to ensure reproducible mechanical positioning of the optical fibers relative to the CCD. Profile and depth dose characterization measurements are presented and show that the prototype provides excellent dose measurement reproducibility (+/-0.8%) in-field and good accuracy (+/-1.6% maximum deviation) relative to the dose measured with an IC10 ionization chamber.

Hard x-ray and gamma-ray imaging and spectroscopy using scintillators coupled to silicon drift detectors

NASA Astrophysics Data System (ADS)

Lechner, P.; Eckhard, R.; Fiorini, C.; Gola, A.; Longoni, A.; Niculae, A.; Peloso, R.; Soltau, H.; Strüder, L.

2008-07-01

Silicon Drift Detectors (SDDs) are used as low-capacitance photon detectors for the optical light emitted by scintillators. The scintillator crystal is directly coupled to the SDD entrance window. The entrance window's transmittance can be optimized for the scintillator characteristic by deposition of a wavelength-selective anti-reflective coating. Compared to conventional photomultiplier tubes the SDD readout offers improved energy resolution and avoids the practical problems of incompatibility with magnetic fields, instrument volume and requirement of high voltage. A compact imaging spectrometer for hard X-rays and γ-rays has been developed by coupling a large area (29 × 26 mm2) monolithic SDD array with 77 hexagonal cells to a single non-structured CsI-scintillator of equal size. The scintillation light generated by the absorption of an energetic photon is seen by a number of detector cells and the position of the photon interaction is reconstructed by the centroid method. The measured spatial resolution of the system (<= 500 μm) is considerably smaller than the SDD cell size (3.2 mm) and in the order required at the focal plane of high energy missions. The energy information is obtained by summing the detector cell signals. Compared to direct converting pixelated detectors, e.g. CdTe with equal position resolution the scintillator-SDD combination requires a considerably lower number of readout channels. In addition it has the advantages of comprehensive material experience, existing technologies, proven long term stability, and practically unlimited availability of high quality material.

Current status of the expanded GRAPES collaboration experiment at Ooty in India

NASA Astrophysics Data System (ADS)

Gupta, S.K.; Anita, H.M.; Iyer, A.; Jagadeesan, P.; Jain, A.; Karthikeyan, S.; Manoharan, P.K.; Mohanty, P.K.; Nayak, P.K.; Rao, B.S.; Ravindran, K.C.; Tanaka, H.; Tonwar, S.C.; Ogio, S.; Okuda, T.; Oshima, A.; Shimizu, N.; Yoshikoshi, T.; Badruddin; Hasan, R.; Ahmad, Shakeel; Mishra, A.P.; Shrivastava, P.K.; Koul, R.; Shah, G.N.; Mir, T.A.; Mufti, S.; Raha, S.; Ghosh, S.; Joarder, P.; Saha, S.; Boruah, K.; Datta, P.; Boruah, P.K.; Baruah, A.G.; Baishya, R.; Saikia, J.; Banerjee, D.; Subramanian, P.; Bhadra, A.; Kumar, S.; Agarwal, R.; Dubey, S.K.; Bhattacharjee, P.

GRAPES-3 experiment employs a high-density array of scintillators and a large area tracking muon telescope. The GRAPES collaboration is being expanded with addition of several major facilities. These include a Cerenkov telescope and low frequency dipole array for the measurement of shower energy. Addition of several modules of muon telescopes to cover a larger area, expansion of the scintillator array with greater separation between detectors. Installation of a neutron monitor is also planned. The current status of the experiment would be summarized.

Two detector arrays for fast neutrons at LANSCE

NASA Astrophysics Data System (ADS)

Haight, R. C.; Lee, H. Y.; Taddeucci, T. N.; O'Donnell, J. M.; Perdue, B. A.; Fotiades, N.; Devlin, M.; Ullmann, J. L.; Laptev, A.; Bredeweg, T.; Jandel, M.; Nelson, R. O.; Wender, S. A.; White, M. C.; Wu, C. Y.; Kwan, E.; Chyzh, A.; Henderson, R.; Gostic, J.

2012-03-01

The neutron spectrum from neutron-induced fission needs to be known in designing new fast reactors, predicting criticality for safety analyses, and developing techniques for global security application. The experimental data base of fission neutron spectra is very incomplete and most present evaluated libraries are based on the approach of the Los Alamos Model. To validate these models and to provide improved data for applications, a program is underway to measure the fission neutron spectrum for a wide range of incident neutron energies using the spallation source of fast neutrons at the Weapons Neutron Research (WNR) facility at the Los Alamos Neutron Science Center (LANSCE). In a double time-of-flight experiment, fission neutrons are detected by arrays of neutron detectors to increase the solid angle and also to investigate possible angular dependence of the fission neutrons. The challenge is to measure the spectrum from low energies, down to 100 keV or so, to energies over 10 MeV, where the evaporation-like spectrum decreases by 3 orders of magnitude from its peak around 1 MeV. For these measurements, we are developing two arrays of neutron detectors, one based on liquid organic scintillators and the other on 6Li-glass detectors. The range of fission neutrons detected by organic liquid scintillators extends from about 600 keV to well over 10 MeV, with the lower limit being defined by the limit of pulse-shape discrimination. The 6Li-glass detectors have a range from very low energies to about 1 MeV, where their efficiency then becomes small. Various considerations and tests are in progress to understand important contributing factors in designing these two arrays and they include selection and characterization of photomultiplier tubes (PM), the performance of relatively thin (1.8 cm) 6Li-glass scintillators on 12.5 cm diameter PM tubes, use of 17.5 cm diameter liquid scintillators with 12.5 cm PM tubes, measurements of detector efficiencies with tagged neutrons from the WNR/LANSCE neutron beam, and efficiency calibration with 252Cf spontaneous fission neutrons. Design considerations and test results are presented.

Measurement of Fission Neutron Spectrum and Multiplicity using a Gamma Tag Double Time-of-flight Setup

NASA Astrophysics Data System (ADS)

Blain, E.; Daskalakis, A.; Danon, Y.

2014-05-01

Recent efforts have been made to improve the prompt fission neutron spectrum and nu-bar measurements for Uranium and Plutonium isotopes particularly in the keV region. A system has been designed at Rensselaer Polytechnic Institute (RPI) utilizing an array of EJ-301 liquid scintillators as well as lithium glass and plastic scintillators to experimentally determine these values. An array of BaF2 detectors was recently obtained from Oak Ridge National Laboratory to be used in conjunction with the neutron detectors. The system uses a novel gamma tagging method for fission which can offer an improvement over conventional fission chambers due to increased sample mass. A coincidence requirement on the gamma detectors from prompt fission gammas is used as the fission tag for the system as opposed to fission fragments in a conventional fission chamber. The system utilizes pulse digitization using Acqiris 8 bit digitizer boards which allow for gamma/neutron pulse height discrimination on the liquid scintillators during post processing. Additionally, a 252Cf fission chamber was designed and constructed at RPI which allowed for optimization and testing of the system without the need for an external neutron source. The characteristics of the gamma tagging method such as false detection rate and detection efficiency were determined using this fission chamber and verified using MCNP Polimi modeling. Prompt fission neutron spectrum data has been taken using the fission chamber focusing on the minimum detectable neutron energy for each of the various detectors. Plastic scintillators were found to offer a significant improvement over traditional liquid scintillators allowing energy measurements down to 50 keV. Background was also characterized for all detectors and will be discussed.

Detector for positronium temperature measurements by two-photon angular correlation

NASA Astrophysics Data System (ADS)

Cecchini, G. G.; Jones, A. C. L.; Fuentes-Garcia, M.; Adams, D. J.; Austin, M.; Membreno, E.; Mills, A. P.

2018-05-01

We report on the design and characterization of a modular γ-ray detector assembly developed for accurate and efficient detection of coincident 511 keV back-to-back γ-rays following electron-positron annihilation. Each modular detector consists of 16 narrow lutetium yttrium oxyorthosilicate scintillators coupled to a multi-anode Hamamatsu H12700B photomultiplier tube. We discuss the operation and optimization of 511 keV γ-ray detection resulting from testing various scintillators and detector arrangements concluding with an estimate of the coincident 511 keV detection efficiency for the intended experiment and a preliminary test representing one-quarter of the completed array.

Observation of Air Shower in Uijeongbu Area using the COREA Prototype Detector System

NASA Astrophysics Data System (ADS)

Cho, Wooram; Shin, Jae-ik; Kwon, Youngjoon; Yang, Jongmann; Nam, Shinwoo; Park, Il H.; Cheon, ByungGu; Kim, Hang Bae; Bhang, Hyoung Chan; Park, Cheolyoung; Kim, Gyhyuk; Choi, Wooseok; Hwang, MyungJin; Shin, Gwangsik

2018-06-01

We report the study of high energy cosmic rays in Uijeongbu area using a cosmic-ray detector array system. The array consists of three detector stations, each of which contains a set of three scintillators and PMTs, a GPS antenna along with data acquisition system. To identify air shower signals originating from a single cosmic ray, time coincidence information is used. We devised a method for estimating the energy range of air shower data detected by an array of only three detectors, using air shower simulation and citing already known energy spectrum. Also, Fast Fourier Transform(FFT) was applied to study isotropy.

Telescope Array Low energy Extension: TALE

NASA Astrophysics Data System (ADS)

Ogio, Shoichi

TALE, the Telescope Array Low Energy extension was designed to lower the energy threshold to about 1016.5 eV. TALE has a surface detector (SD) array made up of 103 scintillation counters (40 with 400 m spacing, 36 with 600 m spacing and 27 with 1.2 km spacing) and a Fluorescence Detector (FD) station consisting of ten FD telescopes working with the Telescope Array Middle Drum FD station, which is made up of 14 telescopes. TALE-FD full operation started in 2013 and the SD array was partially-completed with 16 SDs and continues the operation from 2014. We will describe the history and the current status of the detectors and will make a brief report about the FD and the hybrid analysis results. TALE detector will be completed as a hybrid air shower detector in 2018. We will report the technical details of the detectors, the schedule and the expected performances.

VizieR Online Data Catalog: List of Telescope Array events with E > 57EeV (Abbasi+, 2014)

NASA Astrophysics Data System (ADS)

Abbasi, R. U.; Abe, M.; Abu-Zayyad, T.; Allen, M.; Anderson, R.; Azuma, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Blake, S. A.; Cady, R.; Chae, M. J.; Cheon, B. G.; Chiba, J.; Chikawa, M.; Cho, W. R.; Fujii, T.; Fukushima, M.; Goto, T.; Hanlon, W.; Hayashi, Y.; Hayashida, N.; Hibino, K.; Honda, K.; Ikeda, D.; Inoue, N.; Ishii, T.; Ishimori, R.; Ito, H.; Ivanov, D.; Jui, C. C. H.; Kadota, K.; Kakimoto, F.; Kalashev, O.; Kasahara, K.; Kawai, H.; Kawakami, S.; Kawana, S.; Kawata, K.; Kido, E.; Kim, H. B.; Kim, J. H.; Kitamura, S.; Kitamura, Y.; Kuzmin, V.; Kwon, Y. J.; Lan, J.; Lim, S. I.; Lundquist, J. P.; Machida, K.; Martens, K.; Matsuda, T.; Matsuyama, T.; Matthews, J. N.; Minamino, M.; Mukai, K.; Myers, I.; Nagasawa, K.; Nagataki, S.; Nakamura, T.; Nonaka, T.; Nozato, A.; Ogio, S.; Ogura, J.; Ohnishi, M.; Ohoka, H.; Oki, K.; Okuda, T.; Ono, M.; Oshima, A.; Ozawa, S.; Park, I. H.; Pshirkov, M. S.; Rodriguez, D. C.; Rubtsov, G.; Ryu, D.; Sagawa, H.; Sakurai, N.; Sampson, A. L.; Scott, L. M.; Shah, P. D.; Shibata, F.; Shibata, T.; Shimodaira, H.; Shin, B. K.; Smith, J. D.!; Sokolsk, Y. P.; Springer, R. W.; Stokes, B. T.; Stratton, S. R.; Stroman, T. A.; Suzawa, T.; Takamura, M.; Takeda, M.; Takeishi, R.; Taketa, A.; Takita, M.; Tameda, Y.; Tanaka, H.; Tanaka, K.; Tanaka, M.; Thomas, S. B.; Thomson, G. B.; Tinyakov, P.; Tkachev, I.; Tokuno, H.; Tomida, T.; Troitsky, S.; Tsunesada, Y.; Tsutsumi, K.; Uchihori, Y.; Udo, S.; Urban, F.; Vasiloff, G.; Wong, T.; Yamane, R.; Yamaoka, H.; Yamazaki, K.; Yang, J.; Yashiro, K.; Yoneda, Y.; Yoshida, S.; Yoshii, H.; Zollinger, R.; Zundel, Z.

2017-03-01

The TA is the largest cosmic-ray detector in the northern hemisphere. It consists of a scintillator SD array (Abu-Zayyad et al. 2012NIMPA.689...87A) and three fluorescence detector (FD) stations (Tokuno et al. 2012NIMPA.676...54T). The observatory has been in full operation in Millard Country, Utah, USA (39fdg30N, 112fdg91W; about 1400 m above sea level) since 2008. The TA SD array consists of 507 plastic scintillation detectors each 3 m2 in area and located on a 1.2 km square grid. The array has an area of ~700 km2. The TA SD array observes cosmic-ray-induced extensive air showers with E > ~1 EeV, regardless of weather conditions with a duty cycle near 100% and a wide field of view (FoV). These capabilities ensure a very stable and large geometrical exposure over the northern sky survey in comparison with FD observations that have a duty cycle of ~10%. In this analysis, we used SD data recorded between 2008 May 11 and 2013 May 4. (1 data file).

Three-dimensional cross point readout detector design for including depth information

NASA Astrophysics Data System (ADS)

Lee, Seung-Jae; Baek, Cheol-Ha

2018-04-01

We designed a depth-encoding positron emission tomography (PET) detector using a cross point readout method with wavelength-shifting (WLS) fibers. To evaluate the characteristics of the novel detector module and the PET system, we used the DETECT2000 to perform optical photon transport in the crystal array. The GATE was also used. The detector module is made up of four layers of scintillator arrays, the five layers of WLS fiber arrays, and two sensor arrays. The WLS fiber arrays in each layer cross each other to transport light to each sensor array. The two sensor arrays are coupled to the forward and left sides of the WLS fiber array, respectively. The identification of three-dimensional pixels was determined using a digital positioning algorithm. All pixels were well decoded, with the system resolution ranging from 2.11 mm to 2.29 mm at full width at half maximum (FWHM).

Neutron response characterization for an EJ299-33 plastic scintillation detector

DOE PAGES

Lawrence, Chris C.; Febbraro, Michael; Massey, Thomas N.; ...

2014-05-10

Organic scintillation detectors have shown promise as neutron detectors for characterizing special nuclear materials in various arms-control and homeland security applications. Recent advances have yielded a new plastic scintillator - EJ299-33 - with pulse-shape-discrimination (PSD) capability. Plastic scintillators would have a much expanded range of deployment relative to liquids and crystals. Here in this paper, we present a full characterization of pulse height response to fission-energy neutrons for an EJ299-33 detector with 7.62-by-7.62-cm cylindrical active volume, and compare with an EJ309 liquid scintillator in the same assembly. Scintillation light output relations, energy resolutions, and response matrices are presented for bothmore » detectors. A Continuous spectrum neutron source, obtained via the bombardment of 27Al with 7.44-MeV deuterons at the Edwards Accelerator Facility at Ohio University, was used for the measurement. A new procedure for evaluating and comparing PSD performance is presented which accounts for the effect of the light output relation on the ability to detect low energy neutrons. The EJ299-33 is shown to have considerable deficit in matrix condition, and in PSD figure of merit when compared to EJ309, especially when neutron energy is taken into account. Furthermore the EJ299 is likely to bring a modest PSD capability into a array of held applications that are not accessible to liquids or crystals.« less

Performance of a SiPM based semi-monolithic scintillator PET detector

NASA Astrophysics Data System (ADS)

Zhang, Xianming; Wang, Xiaohui; Ren, Ning; Kuang, Zhonghua; Deng, Xinhan; Fu, Xin; Wu, San; Sang, Ziru; Hu, Zhanli; Liang, Dong; Liu, Xin; Zheng, Hairong; Yang, Yongfeng

2017-10-01

A depth encoding PET detector module using semi-monolithic scintillation crystal single-ended readout by a SiPM array was built and its performance was measured. The semi-monolithic scintillator detector consists of 11 polished LYSO slices measuring 1  ×  11.6  ×  10 mm3. The slices are glued together with enhanced specular reflector (ESR) in between and outside of the slices. The bottom surface of the slices is coupled to a 4  ×  4 SiPM array with a 1 mm light guide and silicon grease between them. No reflector is used on the top surface and two sides of the slices to reduce the scintillation photon reflection. The signals of the 4  ×  4 SiPM array are grouped along rows and columns separately into eight signals. Four SiPM column signals are used to identify the slices according to the center of the gravity of the scintillation photon distribution in the pixelated direction. Four SiPM row signals are used to estimate the y (monolithic direction) and z (depth of interaction) positions according to the center of the gravity and the width of the scintillation photon distribution in the monolithic direction, respectively. The detector was measured with 1 mm sampling interval in both the y and z directions with electronic collimation by using a 0.25 mm diameter 22Na point source and a 1  ×  1  ×  20 mm3 LYSO crystal detector. An average slice based energy resolution of 14.9% was obtained. All slices of 1 mm thick were clearly resolved and a detector with even thinner slices could be used. The y positions calculated with the center of gravity method are different for interactions happening at the same y, but different z positions due to depth dependent edge effects. The least-square minimization and the maximum likelihood positioning algorithms were developed and both methods improved the spatial resolution at the edges of the detector as compared with the center of gravity method. A mean absolute error (MAE) which is defined as the probability-weighted mean of the absolute value of the positioning error is used to evaluate the spatial resolution. An average MAE spatial resolution of ~1.15 mm was obtained in both y and z directions without rejection of the multiple scattering events. The average MAE spatial resolution was ~0.7 mm in both y and z directions after the multiple scattering events were rejected. The timing resolution of the detector is 575 ps. In the next step, long rectangle detector will be built to reduce edge effects and improve the spatial resolution of the semi-monolithic detector. Thick detector up to 20 mm will be explored and the positioning algorithms will be further optimized.

Performance of a SiPM based semi-monolithic scintillator PET detector.

PubMed

Zhang, Xianming; Wang, Xiaohui; Ren, Ning; Kuang, Zhonghua; Deng, Xinhan; Fu, Xin; Wu, San; Sang, Ziru; Hu, Zhanli; Liang, Dong; Liu, Xin; Zheng, Hairong; Yang, Yongfeng

2017-09-21

A depth encoding PET detector module using semi-monolithic scintillation crystal single-ended readout by a SiPM array was built and its performance was measured. The semi-monolithic scintillator detector consists of 11 polished LYSO slices measuring 1  ×  11.6  ×  10 mm 3 . The slices are glued together with enhanced specular reflector (ESR) in between and outside of the slices. The bottom surface of the slices is coupled to a 4  ×  4 SiPM array with a 1 mm light guide and silicon grease between them. No reflector is used on the top surface and two sides of the slices to reduce the scintillation photon reflection. The signals of the 4  ×  4 SiPM array are grouped along rows and columns separately into eight signals. Four SiPM column signals are used to identify the slices according to the center of the gravity of the scintillation photon distribution in the pixelated direction. Four SiPM row signals are used to estimate the y (monolithic direction) and z (depth of interaction) positions according to the center of the gravity and the width of the scintillation photon distribution in the monolithic direction, respectively. The detector was measured with 1 mm sampling interval in both the y and z directions with electronic collimation by using a 0.25 mm diameter 22 Na point source and a 1  ×  1  ×  20 mm 3 LYSO crystal detector. An average slice based energy resolution of 14.9% was obtained. All slices of 1 mm thick were clearly resolved and a detector with even thinner slices could be used. The y positions calculated with the center of gravity method are different for interactions happening at the same y, but different z positions due to depth dependent edge effects. The least-square minimization and the maximum likelihood positioning algorithms were developed and both methods improved the spatial resolution at the edges of the detector as compared with the center of gravity method. A mean absolute error (MAE) which is defined as the probability-weighted mean of the absolute value of the positioning error is used to evaluate the spatial resolution. An average MAE spatial resolution of ~1.15 mm was obtained in both y and z directions without rejection of the multiple scattering events. The average MAE spatial resolution was ~0.7 mm in both y and z directions after the multiple scattering events were rejected. The timing resolution of the detector is 575 ps. In the next step, long rectangle detector will be built to reduce edge effects and improve the spatial resolution of the semi-monolithic detector. Thick detector up to 20 mm will be explored and the positioning algorithms will be further optimized.

Cherenkov and scintillation light separation on the TheiaR &D experiment

NASA Astrophysics Data System (ADS)

Caravaca, Javier; Land, Benjamin

2016-03-01

Identifying by separate the scintillation and Cherenkov light produced in a scintillation medium enables outstanding capabilities for future particle detectors, being the most relevant: allowing particle directionality information in a low energy threshold detector and improved particle identification. The TheiaR &D experiment uses an array of small and fast photomultipliers (PMTs) and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in a scintillation medium, based on the number of produced photoelectrons and the timing information. A charged particle ionizing a scintillation medium produces a prompt Cherenkov cone and late isotropic scintillation light, typically delayed by <1ns. The fast response of our PMTs and DAQ provides a precision well below the ns level, making possible the time separation. Furthermore, the usage of the new developed water-based liquid scintillators (WBLS) provides a medium with a tunable Cherenkov/Scintillation light yield ratio, enhancing the visibility of the dimer Cherenkov light in presence of the scintillation light. Description of the experiment, details of the analysis and preliminary results of the first months of running will be discussed.

A depth-of-interaction PET detector using a stair-shaped reflector arrangement and a single-ended scintillation light readout.

PubMed

Son, Jeong-Whan; Lee, Min Sun; Lee, Jae Sung

2017-01-21

Positron emission tomography (PET) detectors with the ability to encode depth-of-interaction (DOI) information allow us to simultaneously improve the spatial resolution and sensitivity of PET scanners. In this study, we propose a DOI PET detector based on a stair-pattern reflector arrangement inserted between pixelated crystals and a single-ended scintillation light readout. The main advantage of the proposed method is its simplicity; DOI information is decoded from a flood map and the data can be simply acquired by using a single-ended readout system. Another potential advantage is that the two-step DOI detectors can provide the largest peak position distance in a flood map because two-dimensional peak positions can be evenly distributed. We conducted a Monte Carlo simulation and obtained flood maps. Then, we conducted experimental studies using two-step DOI arrays of 5  ×  5 Lu 1.9 Y 0.1 SiO 5 :Ce crystals with a cross-section of 1.7  ×  1.7 mm 2 and different detector configurations: an unpolished single-layer ( U S) array, a polished single-layer ( P S) array and a polished stacked two-layer ( P T) array. For each detector configuration, both air gaps and room-temperature vulcanization (RTV) silicone gaps were tested. Detectors U S and P T showed good peak separation in each scintillator with an average peak-to-valley ratio (PVR) and distance-to-width ratio (DWR) of 2.09 and 1.53, respectively. Detector P S RTV showed lower PVR and DWR (1.65 and 1.34, respectively). The configuration of detector P T Air is preferable for the construction of time-of-flight-DOI detectors because timing resolution was degraded by only about 40 ps compared with that of a non-DOI detector. The performance of detectors U S Air and P S RTV was lower than that of a non-DOI detector, and thus these designs are favorable when the manufacturing cost is more important than timing performance. The results demonstrate that the proposed DOI-encoding method is a promising candidate for PET scanners that require high resolution and sensitivity and operate with conventional acquisition systems.

Simulation study of light transport in laser-processed LYSO:Ce detectors with single-side readout

NASA Astrophysics Data System (ADS)

Bläckberg, L.; El Fakhri, G.; Sabet, H.

2017-11-01

A tightly focused pulsed laser beam can locally modify the crystal structure inside the bulk of a scintillator. The result is incorporation of so-called optical barriers with a refractive index different from that of the crystal bulk, that can be used to redirect the scintillation light and control the light spread in the detector. We here systematically study the scintillation light transport in detectors fabricated using the laser induced optical barrier technique, and objectively compare their potential performance characteristics with those of the two mainstream detector types: monolithic and mechanically pixelated arrays. Among countless optical barrier patterns, we explore barriers arranged in a pixel-like pattern extending all-the-way or half-way through a 20 mm thick LYSO:Ce crystal. We analyze the performance of the detectors coupled to MPPC arrays, in terms of light response functions, flood maps, line profiles, and light collection efficiency. Our results show that laser-processed detectors with both barrier patterns constitute a new detector category with a behavior between that of the two standard detector types. Results show that when the barrier-crystal interface is smooth, no DOI information can be obtained regardless of barrier refractive index (RI). However, with a rough barrier-crystal interface we can extract multiple levels of DOI. Lower barrier RI results in larger light confinement, leading to better transverse resolution. Furthermore we see that the laser-processed crystals have the potential to increase the light collection efficiency, which could lead to improved energy resolution and potentially better timing resolution due to higher signals. For a laser-processed detector with smooth barrier-crystal interfaces the light collection efficiency is simulated to  >42%, and for rough interfaces  >73%. The corresponding numbers for a monolithic crystal is 39% with polished surfaces, and 71% with rough surfaces, and for a mechanically pixelated array 35% with polished pixel surfaces and 59% with rough surfaces.

Simulation study of light transport in laser-processed LYSO:Ce detectors with single-side readout.

PubMed

Bläckberg, L; El Fakhri, G; Sabet, H

2017-10-19

A tightly focused pulsed laser beam can locally modify the crystal structure inside the bulk of a scintillator. The result is incorporation of so-called optical barriers with a refractive index different from that of the crystal bulk, that can be used to redirect the scintillation light and control the light spread in the detector. We here systematically study the scintillation light transport in detectors fabricated using the laser induced optical barrier technique, and objectively compare their potential performance characteristics with those of the two mainstream detector types: monolithic and mechanically pixelated arrays. Among countless optical barrier patterns, we explore barriers arranged in a pixel-like pattern extending all-the-way or half-way through a 20 mm thick LYSO:Ce crystal. We analyze the performance of the detectors coupled to MPPC arrays, in terms of light response functions, flood maps, line profiles, and light collection efficiency. Our results show that laser-processed detectors with both barrier patterns constitute a new detector category with a behavior between that of the two standard detector types. Results show that when the barrier-crystal interface is smooth, no DOI information can be obtained regardless of barrier refractive index (RI). However, with a rough barrier-crystal interface we can extract multiple levels of DOI. Lower barrier RI results in larger light confinement, leading to better transverse resolution. Furthermore we see that the laser-processed crystals have the potential to increase the light collection efficiency, which could lead to improved energy resolution and potentially better timing resolution due to higher signals. For a laser-processed detector with smooth barrier-crystal interfaces the light collection efficiency is simulated to  >42%, and for rough interfaces  >73%. The corresponding numbers for a monolithic crystal is 39% with polished surfaces, and 71% with rough surfaces, and for a mechanically pixelated array 35% with polished pixel surfaces and 59% with rough surfaces.

High-resolution x-ray imaging using a structured scintillator.

PubMed

Hormozan, Yashar; Sychugov, Ilya; Linnros, Jan

2016-02-01

In this study, the authors introduce a new generation of finely structured scintillators with a very high spatial resolution (a few micrometers) compared to conventional scintillators, yet maintaining a thick absorbing layer for improved detectivity. Their concept is based on a 2D array of high aspect ratio pores which are fabricated by ICP etching, with spacings (pitches) of a few micrometers, on silicon and oxidation of the pore walls. The pores were subsequently filled by melting of powdered CsI(Tl), as the scintillating agent. In order to couple the secondary emitted photons of the back of the scintillator array to a CCD device, having a larger pixel size than the pore pitch, an open optical microscope with adjustable magnification was designed and implemented. By imaging a sharp edge, the authors were able to calculate the modulation transfer function (MTF) of this finely structured scintillator. The x-ray images of individually resolved pores suggest that they have been almost uniformly filled, and the MTF measurements show the feasibility of a few microns spatial resolution imaging, as set by the scintillator pore size. Compared to existing techniques utilizing CsI needles as a structured scintillator, their results imply an almost sevenfold improvement in resolution. Finally, high resolution images, taken by their detector, are presented. The presented work successfully shows the functionality of their detector concept for high resolution imaging and further fabrication developments are most likely to result in higher quantum efficiencies.

Development of a circular shape Si-PM-based detector ring for breast-dedicated PET system

NASA Astrophysics Data System (ADS)

Nakanishi, Kouhei; Yamamoto, Seiichi; Watabe, Hiroshi; Abe, Shinji; Fujita, Naotoshi; Kato, Katsuhiko

2018-02-01

In clinical situations, various breast-dedicated positron emission tomography (PET) systems have been used. However, clinical breast-dedicated PET systems have polygonal detector ring. Polygonal detector ring sometimes causes image artifact, so complicated reconstruction algorithm is needed to reduce artifact. Consequently, we developed a circular detector ring for breast-dedicated PET to obtain images without artifact using a simple reconstruction algorithm. We used Lu1.9Gd0.1SiO5 (LGSO) scintillator block which was made of 1.5 x 1.9 x 15 mm pixels that were arranged in an 8 x 24 matrix. As photodetectors, we used silicon photomultiplier (Si-PM) arrays whose channel size was 3 x 3 mm. A detector unit was composed of four scintillator blocks, 16 Si-PM arrays and a light guide. The developed detector unit had angled configuration since the light guide was bending. A detector unit had three gaps with an angle of 5.625° between scintillator blocks. With these configurations, we could arrange 64 scintillator blocks in nearly circular shape (regular 64-sided polygon) using 16 detector units. The use of the smaller number of detector units could reduce the size of the front-end electronics circuits. The inner diameter of the developed detector ring was 260 mm. This size was similar to those of brain PET systems, so our breast-dedicated PET detector ring can measure not only breast but also brain. Measured radial, tangential and axial spatial resolution of the detector ring reconstructed by the filtered back-projection (FBP) algorithm were 2.1 mm FWHM, 2.0 mm FWHM and 1.7 mm FWHM at center of field of view (FOV), respectively. The sensitivity was 2.0% at center of the axial FOV. With the developed detector ring, we could obtain high resolution image of the breast phantom and the brain phantom. We conclude that our developed Si-PM-based detector ring is promising for a high resolution breast-dedicated PET system that can also be used for brain PET system.

SU-F-T-559: High-Resolution Scintillating Fiber Array for In-Vivo Real-Time SRS and SBRT Patient QA

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

Knewtson, T; Pokhrel, S; University of Tennessee Health Science Center, Memphis, TN

2016-06-15

Purpose: A high-resolution scintillating fiber detector was built for in-vivo real-time patient specific quality assurance (QA). The detector is designed for stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS) to monitor treatment delivery and detect real-time deviations from planned dose to increase patient safety and treatment accuracy. Methods: The detector consists of two high-density scintillating fiber arrays layered to form an X-Y grid which can be attached to the accessory tray of a medical linac for SBRT and cone SRS treatment QA. Fiber arrays consist of 128 scintillating fibers embedded within a precision-machined, high-transmission polymer substrate with 0.8mm pitch. Themore » fibers are coupled on both ends to high-sensitivity photodetectors and the output is recorded through a high-speed analog-to-digital converter to capture the linac pulse sequence as treatment delivery progresses. The detector has a software controlled 360 degree rotational system to capture angular beam projections for high-resolution beam profile reconstruction. Results: The detector was validated using SRS cone sizes from 6mm to 34mm and MLC defined field sizes from 5×5mm2 to 100×100mm2. The detector output response is linear with dose and is dose rate independent. Each field can be reconstructed accurately with a spatial resolution of 0.8mm and the current beam output is displayed every 50msec. Dosimetric errors of 1% with respect to the treatment plan can be identified and clinically significant deviations from the expected treatment can be displayed in real-time to alert the therapists. Conclusion: The high resolution detector is capable of reconstructing beam profiles in real-time with submillimeter resolution and 1% dose resolution. This system has the ability to project in-vivo both spatial and dosimetric errors during SBRT and SRS treatments when only a non-clinically significant fraction of the intended dose was delivered. The device has the potential to establish new standards for in-vivo patient specific QA.« less

The “Carpet-3” air shower array to search for diffuse gamma rays with energy Eγ>100TeV

NASA Astrophysics Data System (ADS)

Dzhappuev, D. D.; I, V. B. Petkov V.; Kudzhaev, A. U.; Lidvansky, A. S.; Volchenko, V. I.; Volchenko, G. V.; Gorbacheva, E. A.; Dzaparova, I. M.; Klimenko, N. F.; Kurenya, A. N.; Mikhilova, O. I.; Khadzhiev, M. M.; Yanin, A. F.

2017-12-01

At present an experiment for measuring the flux of cosmic diffuse gamma rays with energy higher than 100 TeV (experiment “Carpet-3”) is being prepared at the Baksan Neutrino Observatory of the Institute for Nuclear Research, Russian Academy of Sciences. The preparation of the experiment implies considerable enlargement of the area of both muon detector and surface part of the shower array. At the moment the plastic scintillation counters with a total continuous area of 410 m2 are installed in the muon detector (MD) underground tunnels, and they are totally equipped with electronics. Adjusting of the counters and their electronic circuits is in progress. Six modules of shower detectors (out of twenty planned to be installed) have already been placed on the surface of the MD absorber. A new liquid scintillation detector is developed for modules of the ground -surface part of the array, whose characteristics are presented. It is shown that the “Carpet-3” air shower array will have the best sensitivity to the flux of primary gamma rays with energies in the range 100TeV - 1PeV, being quite competitive in gamma-ray astronomy at such energies.

Large gamma-ray detector arrays and electromagnetic separators

NASA Astrophysics Data System (ADS)

Lee, I.-Yang

2013-12-01

The use of large gamma-ray detector arrays with electromagnetic separators is a powerful combination. Various types of gamma-ray detectors have been used; some provide high detector efficiency such as scintillation detector array, others use Ge detectors for good energy resolution, and recently developed Ge energy tracking arrays gives both high peak-to-background ratio and position resolution. Similarly, different types of separators were used to optimize the performance under different experimental requirements and conditions. For example, gas-filled separators were used in heavy element studies for their large efficiency and beam rejection factor. Vacuum separators with good isotope resolution were used in transfer and fragmentation reactions for the study of nuclei far from stability. This paper presents results from recent experiments using gamma-ray detector arrays in combination with electromagnetic separators, and discusses the physics opportunities provided by these instruments. In particular, we review the performance of the instruments currently in use, and discuss the requirements of instruments for future radioactive beam accelerator facilities.

Use of internal scintillator radioactivity to calibrate DOI function of a PET detector with a dual-ended-scintillator readout.

PubMed

Bircher, Chad; Shao, Yiping

2012-02-01

Positron emission tomography (PET) detectors that use a dual-ended-scintillator readout to measure depth-of-interaction (DOI) must have an accurate DOI function to provide the relationship between DOI and signal ratios to be used for detector calibration and recalibration. In a previous study, the authors used a novel and simple method to accurately and quickly measure DOI function by irradiating the detector with an external uniform flood source; however, as a practical concern, implementing external uniform flood sources in an assembled PET system is technically challenging and expensive. In the current study, therefore, the authors investigated whether the same method could be used to acquire DOI function from scintillator-generated (i.e., internal) radiation. The authors also developed a method for calibrating the energy scale necessary to select the events within the desired energy window. The authors measured the DOI function of a PET detector with lutetium yttrium orthosilicate (LYSO) scintillators. Radiation events originating from the scintillators' internal Lu-176 beta decay were used to measure DOI functions which were then compared with those measured from both an external uniform flood source and an electronically collimated external point source. The authors conducted these studies with several scintillators of differing geometries (1.5 × 1.5 and 2.0 × 2.0 mm(2) cross-section area and 20, 30, and 40 mm length) and various surface finishes (mirror-finishing, saw-cut rough, and other finishes in between), and in a prototype array. All measured results using internal and external radiation sources showed excellent agreement in DOI function measurement. The mean difference among DOI values for all scintillators measured from internal and external radiation sources was less than 1.0 mm for different scintillator geometries and various surface finishes. The internal radioactivity of LYSO scintillators can be used to accurately measure DOI function in PET detectors, regardless of scintillator geometry or surface finish. Because an external radiation source is not needed, this method of DOI function measurement can be practically applied to individual PET detectors as well as assembled systems.

Use of internal scintillator radioactivity to calibrate DOI function of a PET detector with a dual-ended-scintillator readout

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

Bircher, Chad; Shao Yiping

Purpose: Positron emission tomography (PET) detectors that use a dual-ended-scintillator readout to measure depth-of-interaction (DOI) must have an accurate DOI function to provide the relationship between DOI and signal ratios to be used for detector calibration and recalibration. In a previous study, the authors used a novel and simple method to accurately and quickly measure DOI function by irradiating the detector with an external uniform flood source; however, as a practical concern, implementing external uniform flood sources in an assembled PET system is technically challenging and expensive. In the current study, therefore, the authors investigated whether the same method couldmore » be used to acquire DOI function from scintillator-generated (i.e., internal) radiation. The authors also developed a method for calibrating the energy scale necessary to select the events within the desired energy window. Methods: The authors measured the DOI function of a PET detector with lutetium yttrium orthosilicate (LYSO) scintillators. Radiation events originating from the scintillators' internal Lu-176 beta decay were used to measure DOI functions which were then compared with those measured from both an external uniform flood source and an electronically collimated external point source. The authors conducted these studies with several scintillators of differing geometries (1.5 x 1.5 and 2.0 x 2.0 mm{sup 2} cross-section area and 20, 30, and 40 mm length) and various surface finishes (mirror-finishing, saw-cut rough, and other finishes in between), and in a prototype array. Results: All measured results using internal and external radiation sources showed excellent agreement in DOI function measurement. The mean difference among DOI values for all scintillators measured from internal and external radiation sources was less than 1.0 mm for different scintillator geometries and various surface finishes. Conclusions: The internal radioactivity of LYSO scintillators can be used to accurately measure DOI function in PET detectors, regardless of scintillator geometry or surface finish. Because an external radiation source is not needed, this method of DOI function measurement can be practically applied to individual PET detectors as well as assembled systems.« less

Design and characterization of a real time particle radiography system based on scintillating optical fibers

NASA Astrophysics Data System (ADS)

Longhitano, F.; Lo Presti, D.; Bonanno, D. L.; Bongiovanni, D. G.; Leonora, E.; Randazzo, N.; Reito, S.; Sipala, V.; Gallo, G.

2017-02-01

The fabrication and characterization of a charged particle imaging system composed of a tracker and a residual range detector (RRD) is described. The tracker is composed of four layers of scintillating fibers (SciFi), 500 μm side square section, arranged to form two planes orthogonal to each other. The fibers are coupled to two Multi-Pixel Photon Counter (MPPC) arrays by means of a channel reduction system patented by the Istituto Nazionale di Fisica Nucleare (INFN) (Presti, 2015) [1]. Sixty parallel layers of the same fibers used in the tracker compose the RRD. The various layers are optically coupled to a MPPC array by means of wavelength shifting (WLS) fibers. The sensitive area of the two detectors is 9×9 cm2. The results of the measurements, acquired by the prototypes with CATANA (Cirrone, 2008) [2] proton beam, and a comparison with the simulations of the detectors are presented.

Continuous depth-of-interaction encoding using phosphor-coated scintillators.

PubMed

Du, Huini; Yang, Yongfeng; Glodo, Jarek; Wu, Yibao; Shah, Kanai; Cherry, Simon R

2009-03-21

We investigate a novel detector using a lutetium oxyorthosilicate (LSO) scintillator and YGG (yttrium-aluminum-gallium oxide:cerium, Y(3)(Al,Ga)(5)O(12):Ce) phosphor to construct a detector with continuous depth-of-interaction (DOI) information. The far end of the LSO scintillator is coated with a thin layer of YGG phosphor powder which absorbs some fraction of the LSO scintillation light and emits wavelength-shifted photons with a characteristic decay time of approximately 50 ns. The near end of the LSO scintillator is directly coupled to a photodetector. The photodetector detects a mixture of the LSO light and the light emitted by YGG. With appropriate placement of the coating, the ratio of the light converted from the YGG coating with respect to the unconverted LSO light can be made to depend on the interaction depth. DOI information can then be estimated by inspecting the overall light pulse decay time. Experiments were conducted to optimize the coating method. 19 ns decay time differences across the length of the detector were achieved experimentally when reading out a 1.5 x 1.5 x 20 mm(3) LSO crystal with unpolished surfaces and half-coated with YGG phosphor. The same coating scheme was applied to a 4 x 4 LSO array. Pulse shape discrimination (PSD) methods were studied to extract DOI information from the pulse shape changes. The DOI full-width-half-maximum (FWHM) resolution was found to be approximately 8 mm for this 2 cm thick array.

Continuous Depth-of-Interaction Encoding Using Phosphor-Coated Scintillators

PubMed Central

Du, Huini; Yang, Yongfeng; Glodo, Jarek; Wu, Yibao; Shah, Kanai; Cherry, Simon R.

2009-01-01

We investigate a novel detector using lutetium oxyorthosilicate (LSO) scintillator and YGG (yttrium aluminum gallium oxide:cerium, Y3(Al,Ga)5O12:Ce) phosphor to construct a detector with continuous depth-of-interaction (DOI) information. The far end of the LSO scintillator is coated with a thin layer of YGG phosphor powder which absorbs some fraction of the LSO scintillation light and emits wavelength-shifted photons with a characteristic decay time of ∼ 50 ns. The near end of the LSO scintillator is directly coupled to a photodetector. The photodetector detects a mixture of the LSO light and the light emitted by YGG. With appropriate placement of the coating, the ratio of the light converted from the YGG coating with respect to the unconverted LSO light can be made to depend on the interaction depth. DOI information can then be estimated by inspecting the overall light pulse decay time. Experiments were conducted to optimize the coating method. 19 ns decay time differences across the length of the detector were achieved experimentally when reading out a 1.5×1.5×20 mm3 LSO crystal with unpolished surfaces and half-coated with YGG phosphor. The same coating scheme was applied to a 4 by 4 LSO array. Pulse shape discrimination (PSD) methods were studied to extract DOI information from the pulse shape changes. The DOI full-width-half-maximum (FWHM) resolution was found to be ∼8 mm for this 2 cm thick array. PMID:19258685

ANTS — a simulation package for secondary scintillation Anger-camera type detector in thermal neutron imaging

NASA Astrophysics Data System (ADS)

Morozov, A.; Defendi, I.; Engels, R.; Fraga, F. A. F.; Fraga, M. M. F. R.; Guerard, B.; Jurkovic, M.; Kemmerling, G.; Manzin, G.; Margato, L. M. S.; Niko, H.; Pereira, L.; Petrillo, C.; Peyaud, A.; Piscitelli, F.; Raspino, D.; Rhodes, N. J.; Sacchetti, F.; Schooneveld, E. M.; Van Esch, P.; Zeitelhack, K.

2012-08-01

A custom and fully interactive simulation package ANTS (Anger-camera type Neutron detector: Toolkit for Simulations) has been developed to optimize the design and operation conditions of secondary scintillation Anger-camera type gaseous detectors for thermal neutron imaging. The simulation code accounts for all physical processes related to the neutron capture, energy deposition pattern, drift of electrons of the primary ionization and secondary scintillation. The photons are traced considering the wavelength-resolved refraction and transmission of the output window. Photo-detection accounts for the wavelength-resolved quantum efficiency, angular response, area sensitivity, gain and single-photoelectron spectra of the photomultipliers (PMTs). The package allows for several geometrical shapes of the PMT photocathode (round, hexagonal and square) and offers a flexible PMT array configuration: up to 100 PMTs in a custom arrangement with the square or hexagonal packing. Several read-out patterns of the PMT array are implemented. Reconstruction of the neutron capture position (projection on the plane of the light emission) is performed using the center of gravity, maximum likelihood or weighted least squares algorithm. Simulation results reproduce well the preliminary results obtained with a small-scale detector prototype. ANTS executables can be downloaded from http://coimbra.lip.pt/~andrei/.

A Deuterated Neutron Detector Array For Nuclear (Astro)Physics Studies

NASA Astrophysics Data System (ADS)

Almaraz-Calderon, Sergio; Asher, B. W.; Barber, P.; Hanselman, K.; Perello, J. F.

2016-09-01

The properties of neutron-rich nuclei are at the forefront of research in nuclear structure, nuclear reactions and nuclear astrophysics. The advent of intense rare isotope beams (RIBs) has opened a new door for studies of systems with very short half-lives and possible fascinating properties. Neutron spectroscopic techniques become increasingly relevant when these neutron rich nuclei are used in a variety of experiments. At Florida State University, we are developing a neutron detector array that will allow us to perform high-resolution neutron spectroscopic studies with stable and radioactive beams. The neutron detection system consists of 16 deuterated organic liquid scintillation detectors with fast response and pulse-shape discrimination capabilities. In addition to these properties, there is the potential to use the structure in the pulse-height spectra to extract the energy of the neutrons and thus produce directly excitation spectra. This type of detector uses deuterated benzene (C6D6) as the liquid scintillation medium. The asymmetric nature of the scattering between a neutron and a deuterium in the center of mass produces a pulse-height spectrum from the deuterated scintillator which contains useful information on the initial energy of the neutron. Work supported in part by the State of Florida and NSF Grant No. 1401574.

Improved LabPET Detectors Using Lu1.8Gd0.2SiO5:Ce (LGSO) Scintillator Blocks

NASA Astrophysics Data System (ADS)

Bergeron, Mélanie; Pepin, Catherine M.; Cadorette, Jules; Loignon-Houle, Francis; Fontaine, Réjean; Lecomte, Roger

2015-02-01

The scintillator is one of the key building blocks that critically determine the physical performance of PET detectors. The quest for scintillation crystals with improved characteristics has been crucial in designing scanners with superior imaging performance. Recently, it was shown that the decay time constant of high lutetium content Lu1.8Gd0.2SiO5: Ce (LGSO) scintillators can be adjusted by varying the cerium concentration from 0.025 mol% to 0.75 mol%, thus providing interesting characteristics for phoswich detectors. The high light output (90%-120% NaI) and the improved spectral match of these scintillators with avalanche photodiode (APD) readout promise superior energy and timing resolutions. Moreover, their improved mechanical properties, as compared to conventional LGSO ( Lu0.4Gd1.6SiO5: Ce), make block array manufacturing readily feasible. To verify these assumptions, new phoswich block arrays made of LGSO-90%Lu with low and high mol% Ce concentrations were fabricated and assembled into modules dedicated to the LabPET scanner. Typical crystal decay time constants were 31 ns and 47 ns, respectively. Phoswich crystal identification performed using a digital pulse shape discrimination algorithm yielded an average 8% error. At 511 keV, an energy resolution of 17-21% was obtained, while coincidence timing resolution between 4.6 ns and 5.2 ns was achieved. The characteristics of this new LGSO-based phoswich detector module are expected to improve the LabPET scanner performance. The higher stopping power would increase the detection efficiency. The better timing resolution would also allow the use of a narrower coincidence window, thus minimizing the random event rate. Altogether, these two improvements will significantly enhance the noise equivalent count rate performance of an all LGSO-based LabPET scanner.

Cosmic Ray Measurements by Scintillators with Metal Resistor Semiconductor Avalanche Photo Diodes

ERIC Educational Resources Information Center

Blanco, Francesco; La Rocca, Paola; Riggi, Francesco; Akindinov, Alexandre; Mal'kevich, Dmitry

2008-01-01

An educational set-up for cosmic ray physics experiments is described. The detector is based on scintillator tiles with a readout through metal resistor semiconductor (MRS) avalanche photo diode (APD) arrays. Typical measurements of the cosmic angular distribution at sea level and a study of the East-West asymmetry obtained by such a device are…

Characterization of ParTI Phoswiches Using Charged Pion Beams

NASA Astrophysics Data System (ADS)

Churchman, Emily; Zarrella, Andrew; Youngs, Michael; Yennello, Sherry

2017-09-01

The Partial Truncated Icosahedron (ParTI) detector array consists of 15 phoswiches. Each phoswich is made of two scintillating components - a thallium-doped cesium iodide (CsI(Tl)) crystal and an EJ-212 scintillating plastic - coupled to a photomultiplier tube. Both materials have different scintillation times and are sensitive to both charged and neutral particles. The type of particle and amount of energy deposited determine the shape of the scintillation pulse as a function of time. By integrating the fast and slow signals of the scintillation pulses, a ``Fast vs. Slow Integration'' plot can be created that produces particle identification lines based on the energy deposited in the scintillating materials. Four of these phoswiches were taken to the Paul Scherrer Institute (PSI) in Switzerland where π + , π-, and proton beams were scattered onto the phoswiches to demonstrate their particle identification (PID) capabilities. Using digitizers to record the detector response waveforms, pions can also be identified by the characteristic decay pulse of the muon daughters.

Use of internal scintillator radioactivity to calibrate DOI function of a PET detector with a dual-ended-scintillator readout

PubMed Central

Bircher, Chad; Shao, Yiping

2012-01-01

Purpose: Positron emission tomography (PET) detectors that use a dual-ended-scintillator readout to measure depth-of-interaction (DOI) must have an accurate DOI function to provide the relationship between DOI and signal ratios to be used for detector calibration and recalibration. In a previous study, the authors used a novel and simple method to accurately and quickly measure DOI function by irradiating the detector with an external uniform flood source; however, as a practical concern, implementing external uniform flood sources in an assembled PET system is technically challenging and expensive. In the current study, therefore, the authors investigated whether the same method could be used to acquire DOI function from scintillator-generated (i.e., internal) radiation. The authors also developed a method for calibrating the energy scale necessary to select the events within the desired energy window. Methods: The authors measured the DOI function of a PET detector with lutetium yttrium orthosilicate (LYSO) scintillators. Radiation events originating from the scintillators’ internal Lu-176 beta decay were used to measure DOI functions which were then compared with those measured from both an external uniform flood source and an electronically collimated external point source. The authors conducted these studies with several scintillators of differing geometries (1.5 × 1.5 and 2.0 × 2.0 mm2 cross-section area and 20, 30, and 40 mm length) and various surface finishes (mirror-finishing, saw-cut rough, and other finishes in between), and in a prototype array. Results: All measured results using internal and external radiation sources showed excellent agreement in DOI function measurement. The mean difference among DOI values for all scintillators measured from internal and external radiation sources was less than 1.0 mm for different scintillator geometries and various surface finishes. Conclusions: The internal radioactivity of LYSO scintillators can be used to accurately measure DOI function in PET detectors, regardless of scintillator geometry or surface finish. Because an external radiation source is not needed, this method of DOI function measurement can be practically applied to individual PET detectors as well as assembled systems. PMID:22320787

Experiment to demonstrate separation of Cherenkov and scintillation signals

DOE PAGES

Caravaca, J.; Descamps, F. B.; Land, B. J.; ...

2017-05-05

The ability to separately identify the Cherenkov and scintillation light components produced in scintillating mediums holds the potential for a major breakthrough in neutrino detection technology, allowing development of a large, low-threshold, directional detector with a broad physics program. Furthermore, the CHESS (CHErenkov/Scintillation Separation) experiment employs an innovative detector design with an array of small, fast photomultiplier tubes and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in a scintillating medium based on photon hit time and detected photoelectron density. Our paper describes the physical properties and calibration of CHESS along with first results. The ability to reconstructmore » Cherenkov rings are demonstrated in a water target, and a time precision of 338 ± 12 ps FWHM is achieved. Finally, Monte Carlo–based predictions for the ring imaging sensitivity with a liquid scintillator target predict an efficiency for identifying Cherenkov hits of 94 ± 1 % and 81 ± 1 % in pure linear alkyl benzene (LAB) and LAB loaded with 2 g/L of a fluor, PPO, respectively, with a scintillation contamination of 12 ± 1 % and 26 ± 1 % .« less

Experiment to demonstrate separation of Cherenkov and scintillation signals

NASA Astrophysics Data System (ADS)

Caravaca, J.; Descamps, F. B.; Land, B. J.; Wallig, J.; Yeh, M.; Orebi Gann, G. D.

2017-05-01

The ability to separately identify the Cherenkov and scintillation light components produced in scintillating mediums holds the potential for a major breakthrough in neutrino detection technology, allowing development of a large, low-threshold, directional detector with a broad physics program. The CHESS (CHErenkov/Scintillation Separation) experiment employs an innovative detector design with an array of small, fast photomultiplier tubes and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in a scintillating medium based on photon hit time and detected photoelectron density. This paper describes the physical properties and calibration of CHESS along with first results. The ability to reconstruct Cherenkov rings is demonstrated in a water target, and a time precision of 338 ±12 ps FWHM is achieved. Monte Carlo-based predictions for the ring imaging sensitivity with a liquid scintillator target predict an efficiency for identifying Cherenkov hits of 94 ±1 % and 81 ±1 % in pure linear alkyl benzene (LAB) and LAB loaded with 2 g/L of a fluor, PPO, respectively, with a scintillation contamination of 12 ±1 % and 26 ±1 % .

A helical scintillating fiber hodoscope

NASA Astrophysics Data System (ADS)

Altmeier, M.; Bauer, F.; Bisplinghoff, J.; Bissel, T.; Bollmann, R.; Busch, M.; Büßer, K.; Colberg, T.; Demirörs, L.; Diehl, O.; Dohrmann, F.; Engelhardt, H. P.; Eversheim, P. D.; Felden, O.; Gebel, R.; Glende, M.; Greiff, J.; Groß, A.; Groß-Hardt, R.; Hinterberger, F.; Jahn, R.; Jeske, M.; Jonas, E.; Krause, H.; Lahr, U.; Langkau, R.; Lindemann, T.; Lindlein, J.; Maier, R.; Maschuw, R.; Mayer-Kuckuck, T.; Meinerzhagen, A.; Nähle, O.; Pfuff, M.; Prasuhn, D.; Rohdjeß, H.; Rosendaal, D.; von Rossen, P.; Sanz, B.; Schirm, N.; Schulz-Rojahn, M.; Schwarz, V.; Scobel, W.; Thomas, S.; Trelle, H. J.; Weise, E.; Wellinghausen, A.; Wiedmann, W.; Woller, K.; Ziegler, R.; EDDA Collaboration

1999-07-01

A novel scintillating fiber hodoscope in helically cylindric geometry has been developed for detection of low multiplicity events of fast protons and other light charged particles in the internal target experiment EDDA at the Cooler Synchrotron COSY. The hodoscope consists of 640 scintillating fibers (2.5 mm diameter), arranged in four layers surrounding the COSY beam pipe. The fibers are helically wound in opposing directions and read out individually using 16-channel photomultipliers connected to a modified commercial encoding system. The detector covers an angular range of 9°⩽ Θ⩽72° and 0°⩽ ϕ⩽360° in the lab frame. The detector length is 590 mm, the inner diameter 161 mm. Geometry and granularity of the hodoscope afford a position resolution of about 1.3 mm. The detector design took into consideration a maximum of reliability and a minimum of maintenance. An LED array may be used for monitoring purposes.

A sub-millimeter resolution detector module for small-animal PET applications

NASA Astrophysics Data System (ADS)

Sacco, I.; Dohle, R.; Fischer, P.; Gola, A.; Piemonte, C.; Ritzert, M.

2017-01-01

We present a gamma detection module optimized for very high resolution PET applications, able to resolve arrays of scintillating crystals with sub-millimeter pitch. The detector is composed of a single ceramic substrate (LTCC): it hosts four flip-chip mounted PETA5 ASICs on the bottom side and an array of SiPM sensors on the top surface, fabricated in HD-RGB technology by FBK. Each chip has 36 channels, for a maximum of 144 readout channels on a sensitive area of about 32 mm × 32 mm. The module is MR-compatible. The thermal decoupling of the readout electronics from the photon sensors is obtained with an efficient internal liquid channel, integrated within the ceramic substrate. Two modules have been designed, based on different SiPM topologies: • Light spreader-based: an array of 12 × 12 SiPMs, with an overall pitch of 2.5 mm, is coupled with a scintillators array using a 1 mm thick glass plate. The light from one crystal is spread over a group of SiPMs, which are read out in parallel using PETA5 internal neighbor logic. • Interpolating SiPM-based: ISiPMs are intrinsic position-sensitive sensors. The photon diodes in the array are connected to one of the four available outputs so that the center of gravity of any bunch of detected photons can be reconstructed using a proper weight function of the read out amplitudes. An array of ISiPMs, each 7.5 mm× 5 mm sized, is directly coupled with the scintillating crystals. Both modules can clearly resolve LYSO arrays with a pitch of only 0.833 mm. The detector can be adjusted for clinical PET, where it has already shown ToF resolution of about 230 ps CRT at FWHM. The module designs, their features and results are described.

A sub-millimeter resolution PET detector module using a multi-pixel photon counter array

NASA Astrophysics Data System (ADS)

Song, Tae Yong; Wu, Heyu; Komarov, Sergey; Siegel, Stefan B.; Tai, Yuan-Chuan

2010-05-01

A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 × 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 × 0.8 × 3 mm3 and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 × 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and ±5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when ±10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing among multiple MPPC and to diffuse and direct scintillation light can reduce the nonlinearity of the detector response within the limited dynamic range of a typical MPPC. As a result, the proposed PET detector module has the potential to be refined for use in high-resolution PET insert applications.

A sub-millimeter resolution PET detector module using a multi-pixel photon counter array.

PubMed

Song, Tae Yong; Wu, Heyu; Komarov, Sergey; Siegel, Stefan B; Tai, Yuan-Chuan

2010-05-07

A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 x 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 x 0.8 x 3 mm(3) and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 x 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and +/-5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when +/-10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing among multiple MPPC and to diffuse and direct scintillation light can reduce the nonlinearity of the detector response within the limited dynamic range of a typical MPPC. As a result, the proposed PET detector module has the potential to be refined for use in high-resolution PET insert applications.

A sub-millimeter resolution PET detector module using a multi-pixel photon counter array

PubMed Central

Song, Tae Yong; Wu, Heyu; Komarov, Sergey; Siegel, Stefan B; Tai, Yuan-Chuan

2010-01-01

A PET block detector module using an array of sub-millimeter lutetium oxyorthosilicate (LSO) crystals read out by an array of surface-mount, semiconductor photosensors has been developed. The detector consists of a LSO array, a custom acrylic light guide, a 3 × 3 multi-pixel photon counter (MPPC) array (S10362-11-050P, Hamamatsu Photonics, Japan) and a readout board with a charge division resistor network. The LSO array consists of 100 crystals, each measuring 0.8 × 0.8 × 3 mm3 and arranged in 0.86 mm pitches. A Monte Carlo simulation was used to aid the design and fabrication of a custom light guide to control distribution of scintillation light over the surface of the MPPC array. The output signals of the nine MPPC are multiplexed by a charge division resistor network to generate four position-encoded analog outputs. Flood image, energy resolution and timing resolution measurements were performed using standard NIM electronics. The linearity of the detector response was investigated using gamma-ray sources of different energies. The 10 × 10 array of 0.8 mm LSO crystals was clearly resolved in the flood image. The average energy resolution and standard deviation were 20.0% full-width at half-maximum (FWHM) and ±5.0%, respectively, at 511 keV. The timing resolution of a single MPPC coupled to a LSO crystal was found to be 857 ps FWHM, and the value for the central region of detector module was 1182 ps FWHM when ±10% energy window was applied. The nonlinear response of a single MPPC when used to read out a single LSO was observed among the corner crystals of the proposed detector module. However, the central region of the detector module exhibits significantly less nonlinearity (6.5% for 511 keV). These results demonstrate that (1) a charge-sharing resistor network can effectively multiplex MPPC signals and reduce the number of output signals without significantly degrading the performance of a PET detector and (2) a custom light guide to permit light sharing among multiple MPPC and to diffuse and direct scintillation light can reduce the nonlinearity of the detector response within the limited dynamic range of a typical MPPC. As a result, the proposed PET detector module has the potential to be refined for use in high-resolution PET insert applications. PMID:20393236

First data with the Hybrid Array of Gamma Ray Detector (HAGRiD)

NASA Astrophysics Data System (ADS)

Smith, K.; Baugher, T.; Burcher, S.; Carter, A. B.; Cizewski, J. A.; Chipps, K. A.; Febbraro, M.; Grzywacz, R.; Jones, K. L.; Munoz, S.; Pain, S. D.; Paulauskas, S. V.; Ratkiewicz, A.; Schmitt, K. T.; Thornsberry, C.; Toomey, R.; Walter, D.; Willoughby, H.

2018-01-01

The structure of nuclei provides insight into astrophysical reaction rates that are difficult to measure directly. These studies are often performed with transfer reactions and β-decay measurements. These experiments benefit from particle-γ coincidence measurements which provide information beyond that of particle detection alone. The Hybrid Array of Gamma Ray Detectors (HAGRiD) of LaBr3(Ce) scintillators has been designed with this purpose in mind. The design of the array permits it to be coupled with particle detector systems, such as the Oak Ridge Rutgers University Barrel Array (ORRUBA) of silicon detectors and the Versatile Array of Neutron Detectors at Low Energy (VANDLE). It is also designed to operate with the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) advanced target system. HAGRiD's design avoids compromising the charged-particle angular resolution due to compact geometries which are often used to increase the γ efficiency in other systems. First experiments with HAGRiD coupled to VANDLE as well as ORRUBA and JENSA are discussed.

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

Aab, A.; Abreu, P.; Aglietta, M.

Here, AMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of the Pierre Auger Observatory designed to extend its energy range of detection and to directly measure the muon content of the cosmic ray primary particle showers. The array will be formed by an infill of surface water-Cherenkov detectors associated with buried scintillation counters employed for muon counting. Each counter is composed of three scintillation modules, with a 10 m 2 detection area per module. In this paper, a new generation of detectors, replacing the current multi-pixel photomultiplier tube (PMT) with silicon photo sensors (aka. SiPMs), ismore » proposed. The selection of the new device and its front-end electronics is explained. A method to calibrate the counting system that ensures the performance of the detector is detailed. This method has the advantage of being able to be carried out in a remote place such as the one where the detectors are deployed. High efficiency results, i.e. 98% efficiency for the highest tested overvoltage, combined with a low probability of accidental counting (~2%), show a promising performance for this new system.« less

The LUCIFER/CUPID-0 demonstrator: searching for the neutrinoless double-beta decay with Zn82Se scintillating bolometers

NASA Astrophysics Data System (ADS)

Artusa, D. R.; Balzoni, A.; Beeman, J. W.; Bellini, F.; Biassoni, M.; Brofferio, C.; Camacho, A.; Capelli, S.; Cardani, L.; Carniti, P.; Casali, N.; Cassina, L.; Clemenza, M.; Cremonesi, O.; Cruciani, A.; D'Addabbo, A.; Dafinei, I.; Di Domizio, S.; di Vacri, M. L.; Ferroni, F.; Gironi, L.; Giuliani, A.; Gotti, C.; Keppel, G.; Maino, M.; Mancuso, M.; Martinez, M.; Morganti, S.; Nagorny, S. S.; Nastasi, M.; Nisi, S.; Nones, C.; Orlandi, D.; Pagnanini, L.; Pallavicini, M.; Palmieri, V.; Pattavina, L.; Pavan, M.; Pessina, G.; Pettinacci, V.; Pirro, S.; Pozzi, S.; Previtali, E.; Puiu, A.; Rusconi, C.; Schäffner, K.; Tomei, C.; Vignati, M.; Zolotarova, A.

2017-09-01

Future experiments on neutrinoless double beta-decay with the aim of exploring the inverted hierarchy region have to employ detectors with excellent energy resolution and zero background in the energy region of interest. Cryogenic scintillating bolometers turn out to be a suitable candidate since they offer particle discrimination: the dual channel detection of the heat and the scintillation light signal allows for particle identification. In particular such detectors permit for a suppression of α-induced backgrounds, a key-issue for next-generation tonne-scale bolometric experiments. We report on the progress and current status of the LUCIFER/CUPID-0 demonstrator, the first array of scintillating bolometers based on enriched Zn82Se crystals which is expected to start data taking in 2016 and the potential of this detection technique for a future tonne-scale bolometric experiment after CUORE.

Akeno 20 km (2) air shower array (Akeno Branch)

NASA Technical Reports Server (NTRS)

Teshima, M.; Ohoka, H.; Matsubara, Y.; Hara, T.; Hatano, Y.; Hayashida, N.; He, C. X.; Honda, M.; Ishikawa, F.; Kamata, K.

1985-01-01

As the first stage of the future huge array, the Akeno air shower array was expanded to about 20 sq. km. by adding 19 scintillation detectors of 2.25 sq m area outside the present 1 sq. km. Akeno array with a new data collection system. These detectors are spaced about 1km from each other and connected by two optical fiber cables. This array has been in partial operation from 8th, Sep. 1984 and full operation from 20th, Dec. 1984. 20 sq m muon stations are planned to be set with 2km separation and one of them is now under construction. The origin of the highest energy cosmic rays is studied.

Scalable gamma-ray camera for wide-area search based on silicon photomultipliers array

NASA Astrophysics Data System (ADS)

Jeong, Manhee; Van, Benjamin; Wells, Byron T.; D'Aries, Lawrence J.; Hammig, Mark D.

2018-03-01

Portable coded-aperture imaging systems based on scintillators and semiconductors have found use in a variety of radiological applications. For stand-off detection of weakly emitting materials, large volume detectors can facilitate the rapid localization of emitting materials. We describe a scalable coded-aperture imaging system based on 5.02 × 5.02 cm2 CsI(Tl) scintillator modules, each partitioned into 4 × 4 × 20 mm3 pixels that are optically coupled to 12 × 12 pixel silicon photo-multiplier (SiPM) arrays. The 144 pixels per module are read-out with a resistor-based charge-division circuit that reduces the readout outputs from 144 to four signals per module, from which the interaction position and total deposited energy can be extracted. All 144 CsI(Tl) pixels are readily distinguishable with an average energy resolution, at 662 keV, of 13.7% FWHM, a peak-to-valley ratio of 8.2, and a peak-to-Compton ratio of 2.9. The detector module is composed of a SiPM array coupled with a 2 cm thick scintillator and modified uniformly redundant array mask. For the image reconstruction, cross correlation and maximum likelihood expectation maximization methods are used. The system shows a field of view of 45° and an angular resolution of 4.7° FWHM.

A scintillator geometry suitable for very small PET gantries

NASA Astrophysics Data System (ADS)

Gonzalez, A. J.; Gonzalez-Montoro, A.; Aguilar, A.; Cañizares, G.; Martí, R.; Iranzo, S.; Lamprou, E.; Sanchez, S.; Sanchez, F.; Benlloch, J. M.

2017-12-01

In this work we are describing a novel approach to the scintillator crystal configuration as used in nuclear medicine imaging. Our design is related to the coupling in one PET module of the two separate crystal configurations used so far there: monolithic and crystal arrays. The particular design we have studied is based on a two-layer scintillator approach (hybrid) composed of a monolithic LYSO crystal (5-6 mm thickness) and a LYSO crystal array with 4-5 mm height (0.8 and 1 mm pixels). We show here the detector block performance, in terms of spatial, energy and DOI information, to be used as a module in the design of PET scanners. The design we propose allows one to achieve accurate three-dimensional spatial resolution (including DOI information) while assuring high detection efficiency at reasonable cost. Moreover, the proposed design improves the spatial response uniformity across the whole detector module, and especially at the edge region. The crystal arrays are mounted in the front and were well resolved. The monolithic crystal inserted between crystal array and the photosensor, provided measured FWHM resolution as good as 1.5-1.7 mm including the 1 mm source size. The monolithic block achieved a DOI resolution (FWHM) nearing 3 mm. We compared these results with an approach in which we use a single monolithic block with total volume equals to the hybrid approach. In general, comparable performances were obtained.

Muon counting using silicon photomultipliers in the AMIGA detector of the Pierre Auger observatory

NASA Astrophysics Data System (ADS)

Aab, A.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Samarai, I. Al; Albuquerque, I. F. M.; Allekotte, I.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Ambrosio, M.; Anastasi, G. A.; Anchordoqui, L.; Andrada, B.; Andringa, S.; Aramo, C.; Arqueros, F.; Arsene, N.; Asorey, H.; Assis, P.; Aublin, J.; Avila, G.; Badescu, A. M.; Balaceanu, A.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Biteau, J.; Blaess, S. G.; Blanco, A.; Blazek, J.; Bleve, C.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Borodai, N.; Botti, A. M.; Brack, J.; Brancus, I.; Bretz, T.; Bridgeman, A.; Briechle, F. L.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Cancio, A.; Canfora, F.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Clay, R. W.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Cronin, J.; Dallier, R.; D'Amico, S.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Jong, S. J.; De Mauro, G.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; Debatin, J.; del Peral, L.; Deligny, O.; Di Giulio, C.; Di Matteo, A.; Díaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; D'Olivo, J. C.; Dorofeev, A.; dos Anjos, R. C.; Dova, M. T.; Dundovic, A.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Fratu, O.; Freire, M. M.; Fujii, T.; Fuster, A.; García, B.; Garcia-Pinto, D.; Gaté, F.; Gemmeke, H.; Gherghel-Lascu, A.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Głas, D.; Glaser, C.; Glass, H.; Golup, G.; Gómez Berisso, M.; Gómez Vitale, P. F.; González, N.; Gookin, B.; Gordon, J.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Hasankiadeh, Q.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huege, T.; Hulsman, J.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Johnsen, J. A.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Keilhauer, B.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Kuempel, D.; Kukec Mezek, G.; Kunka, N.; Kuotb Awad, A.; LaHurd, D.; Latronico, L.; Lauscher, M.; Lebrun, P.; Legumina, R.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopes, L.; López, R.; López Casado, A.; Luce, Q.; Lucero, A.; Malacari, M.; Mallamaci, M.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Mariş, I. C.; Marsella, G.; Martello, D.; Martinez, H.; Martínez Bravo, O.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melo, D.; Menshikov, A.; Messina, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Mockler, D.; Molina-Bueno, L.; Mollerach, S.; Montanet, F.; Morello, C.; Mostafá, M.; Müller, G.; Muller, M. A.; Müller, S.; Naranjo, I.; Navas, S.; Nellen, L.; Neuser, J.; Nguyen, P. H.; Niculescu-Oglinzanu, M.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, H.; Núñez, L. A.; Ochilo, L.; Oikonomou, F.; Olinto, A.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; Pedreira, F.; Pȩkala, J.; Pelayo, R.; Peña-Rodriguez, J.; Pereira, L. A. S.; Perrone, L.; Peters, C.; Petrera, S.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Ramos-Pollant, R.; Rautenberg, J.; Ravignani, D.; Reinert, D.; Revenu, B.; Ridky, J.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Rogozin, D.; Rosado, J.; Roth, M.; Roulet, E.; Rovero, A. C.; Saffi, S. J.; Saftoiu, A.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sanabria Gomez, J. D.; Sánchez, F.; Sanchez-Lucas, P.; Santos, E. M.; Santos, E.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sarmiento-Cano, C.; Sato, R.; Scarso, C.; Schauer, M.; Scherini, V.; Schieler, H.; Schmidt, D.; Scholten, O.; Schovánek, P.; Schröder, F. G.; Schulz, A.; Schulz, J.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sigl, G.; Silli, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sonntag, S.; Sorokin, J.; Squartini, R.; Stanca, D.; Stanič, S.; Stasielak, J.; Strafella, F.; Suarez, F.; Suarez Durán, M.; Sudholz, T.; Suomijärvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Taborda, O. A.; Tapia, A.; Tepe, A.; Theodoro, V. M.; Timmermans, C.; Todero Peixoto, C. J.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Torri, M.; Travnicek, P.; Trini, M.; Ulrich, R.; Unger, M.; Urban, M.; Valbuena-Delgado, A.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Villaseñor, L.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weindl, A.; Wiencke, L.; Wilczyński, H.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yang, L.; Yelos, D.; Yushkov, A.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zepeda, A.; Zimmermann, B.; Ziolkowski, M.; Zong, Z.; Zuccarello, F.

2017-03-01

AMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of the Pierre Auger Observatory designed to extend its energy range of detection and to directly measure the muon content of the cosmic ray primary particle showers. The array will be formed by an infill of surface water-Cherenkov detectors associated with buried scintillation counters employed for muon counting. Each counter is composed of three scintillation modules, with a 10 m2 detection area per module. In this paper, a new generation of detectors, replacing the current multi-pixel photomultiplier tube (PMT) with silicon photo sensors (aka. SiPMs), is proposed. The selection of the new device and its front-end electronics is explained. A method to calibrate the counting system that ensures the performance of the detector is detailed. This method has the advantage of being able to be carried out in a remote place such as the one where the detectors are deployed. High efficiency results, i.e. 98% efficiency for the highest tested overvoltage, combined with a low probability of accidental counting (~2%), show a promising performance for this new system.

Muon counting using silicon photomultipliers in the AMIGA detector of the Pierre Auger observatory

DOE PAGES

Aab, A.; Abreu, P.; Aglietta, M.; ...

2017-03-03

Here, AMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of the Pierre Auger Observatory designed to extend its energy range of detection and to directly measure the muon content of the cosmic ray primary particle showers. The array will be formed by an infill of surface water-Cherenkov detectors associated with buried scintillation counters employed for muon counting. Each counter is composed of three scintillation modules, with a 10 m 2 detection area per module. In this paper, a new generation of detectors, replacing the current multi-pixel photomultiplier tube (PMT) with silicon photo sensors (aka. SiPMs), ismore » proposed. The selection of the new device and its front-end electronics is explained. A method to calibrate the counting system that ensures the performance of the detector is detailed. This method has the advantage of being able to be carried out in a remote place such as the one where the detectors are deployed. High efficiency results, i.e. 98% efficiency for the highest tested overvoltage, combined with a low probability of accidental counting (~2%), show a promising performance for this new system.« less

The homestake surface-underground scintillators: Initial results

NASA Technical Reports Server (NTRS)

Cherry, M. L.; Corbato, S.; Daily, T.; Fenyves, E. J.; Kieda, D.; Lande, K.; Lee, C. K.

1986-01-01

The first 70 tons of the 140-ton Large Area Scintillation Detector (LASD) have been operating since Jan. 1985 at a depth of 4850 ft. (4200 m.w.e.) in the Homestake Gold Mine, Lead, S.D. A total of 4 x 10(4) high-energy muons (E sub mu is approx. 2.7 TeV at the surface) have been detected. The remainder of the detector is scheduled to be in operation by the Fall of 1985. In addition, a surface air shower array is under construction. The first 27 surface counters, spaced out over an area of 270' x 500', began running in June, 1985. The LASD performance, the potential of the combined shower array and underground muon experiment for detecting point sources, and the initial results of a search for periodic emission from Cygnus X-3 are discussed.

Hexagonal Uniformly Redundant Arrays (HURAs) for scintillator based coded aperture neutron imaging

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

Gamage, K.A.A.; Zhou, Q.

2015-07-01

A series of Monte Carlo simulations have been conducted, making use of the EJ-426 neutron scintillator detector, to investigate the potential of using hexagonal uniformly redundant arrays (HURAs) for scintillator based coded aperture neutron imaging. This type of scintillator material has a low sensitivity to gamma rays, therefore, is of particular use in a system with a source that emits both neutrons and gamma rays. The simulations used an AmBe source, neutron images have been produced using different coded-aperture materials (boron- 10, cadmium-113 and gadolinium-157) and location error has also been estimated. In each case the neutron image clearly showsmore » the location of the source with a relatively small location error. Neutron images with high resolution can be easily used to identify and locate nuclear materials precisely in nuclear security and nuclear decommissioning applications. (authors)« less

Telescope Array Results on UHE Cosmic Rays and the Plan

NASA Astrophysics Data System (ADS)

Sagawa, Hiroyuki

The Telescope Array (TA) is the largest experiment in the Northern Hemisphere studying the origin and nature of ultra-high-energy cosmic rays. The TA detector consists of a surface array of 507 scintillation counters covering approximately 700 km2, and 38 fluorescence telescopes located at three sites looking over the surface array. Here, recent TA results using the first five years of data and our ongoing and near-future plans are presented.

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

Lawrence, Chris C.; Febbraro, Michael; Massey, Thomas N.

Organic scintillation detectors have shown promise as neutron detectors for characterizing special nuclear materials in various arms-control and homeland security applications. Recent advances have yielded a new plastic scintillator - EJ299-33 - with pulse-shape-discrimination (PSD) capability. Plastic scintillators would have a much expanded range of deployment relative to liquids and crystals. Here in this paper, we present a full characterization of pulse height response to fission-energy neutrons for an EJ299-33 detector with 7.62-by-7.62-cm cylindrical active volume, and compare with an EJ309 liquid scintillator in the same assembly. Scintillation light output relations, energy resolutions, and response matrices are presented for bothmore » detectors. A Continuous spectrum neutron source, obtained via the bombardment of 27Al with 7.44-MeV deuterons at the Edwards Accelerator Facility at Ohio University, was used for the measurement. A new procedure for evaluating and comparing PSD performance is presented which accounts for the effect of the light output relation on the ability to detect low energy neutrons. The EJ299-33 is shown to have considerable deficit in matrix condition, and in PSD figure of merit when compared to EJ309, especially when neutron energy is taken into account. Furthermore the EJ299 is likely to bring a modest PSD capability into a array of held applications that are not accessible to liquids or crystals.« less

Automated response matching for organic scintillation detector arrays

NASA Astrophysics Data System (ADS)

Aspinall, M. D.; Joyce, M. J.; Cave, F. D.; Plenteda, R.; Tomanin, A.

2017-07-01

This paper identifies a digitizer technology with unique features that facilitates feedback control for the realization of a software-based technique for automatically calibrating detector responses. Three such auto-calibration techniques have been developed and are described along with an explanation of the main configuration settings and potential pitfalls. Automating this process increases repeatability, simplifies user operation, enables remote and periodic system calibration where consistency across detectors' responses are critical.

A prototype scintillating fibre beam profile monitor for Ion Therapy beams

NASA Astrophysics Data System (ADS)

Leverington, B. D.; Dziewiecki, M.; Renner, L.; Runze, R.

2018-05-01

A prototype plastic scintillating fibre based beam profile monitor was tested at the Heidelberg Ion Therapy Centre/Heidelberg Ionenstrahl Therapiezentrum (HIT) in 2016 to determine its beam property reconstruction performance and the feasibility of further developing an expanded system. At HIT protons, helium, carbon, and oxygen ions are available for therapy and experiments. The beam can be scanned in two dimensions using fast deflection magnets. A tracking system is used to monitor beam position and to adjust scanning magnet currents online. A new detector system with a finer granularity and without the drift time delay of the current MWPC system with a similar amount of material along the beamline would prove valuable in patient treatment. The sensitive detector components in the tested prototype detector are double-clad Kuraray SCSF-78MJ scintillating fibres with a diameter of 0.250 mm wound as a thin multi-layer ribbon. The scintillation light is detected at the end of the ribbon with Hamamatsu S11865-64 photodiode arrays with a pitch of 0.8 mm. Commercial or readily available readout electronics have been used to evaluate the system feasibility. The results shown in this paper include the linearity with respect to beam intensity, the RMS of the beam intensity as measured by two planes, along with the RMS of the mean position, and the measured beam width RMS. The Signal-to-Noise ratio of the current system is also measured as an indicator of potential performance. Additionally, the non-linear light yield of the scintillating fibres as measured by the photodiode arrays is compared to two models which describe the light yield as a function of the ion stopping power and Lorentz β.

Instrumentation development for an array of water Cherenkov detectors for extensive air shower experiments

NASA Astrophysics Data System (ADS)

Sheidaei, F.; Bahmanabadi, M.; Keivani, A.; Samimi, J.

2009-11-01

A new small array of Cherenkov detectors has been deployed in Tehran, 1200 m above sea level. This array contains four tanks of distilled water with a diameter of 64 cm and a height of 130 cm. The effective area of each tank is about 1382 cm2. They are used to detect air showers and to record the arrival time of the secondary particles. We have collected about 640 000 extensive air showers (EAS) in 8298 h of observation time from November 2006 to October 2007. The distribution of air showers in zenith and azimuth angles has been studied and a cosnθ distribution with n = 6.02 ± 0.01 was obtained for the zenith angle distribution. An asymmetry has been observed in the azimuthal distribution of EAS of cosmic rays due to geomagnetic field. The first and second amplitudes of the asymmetry are AI = 0.183 ± 0.001 and AII = 0.038 ± 0.001. Since the recent results are in good agreement with our previous results of scintillation detectors, and tanks of distilled water are cheaper, we prefer to use them instead of scintillators in a future larger array. By simulation, we have improved the size of the detectors to yield the highest efficiency. The best dimensions for each tank with a photomultiplier tube in the center of its lid are 40 cm in diameter and 60 cm in height.

The Data Acquisition System of the Stockholm Educational Air Shower Array

NASA Astrophysics Data System (ADS)

Hofverberg, P.; Johansson, H.; Pearce, M.; Rydstrom, S.; Wikstrom, C.

2005-12-01

The Stockholm Educational Air Shower Array (SEASA) project is deploying an array of plastic scintillator detector stations on school roofs in the Stockholm area. Signals from GPS satellites are used to time synchronise signals from the widely separated detector stations, allowing cosmic ray air showers to be identified and studied. A low-cost and highly scalable data acquisition system has been produced using embedded Linux processors which communicate station data to a central server running a MySQL database. Air shower data can be visualised in real-time using a Java-applet client. It is also possible to query the database and manage detector stations from the client. In this paper, the design and performance of the system are described

High energy hadrons in air shower cores at mountain altitude

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

van Staa, R.; Aschenbach, B.; Boehm, E.

1974-01-01

At the Pic du Midi (730 g cm/sup -2/) in France an air shower array has been operated to study high-energy hadrons in air shower cores. The array consists of 13 scintillation counters of 0.25 mi each and a 14 mi high energy hadron detector. 2050 showers please delete the above abstract no 21733====

Position sensitivity by light splitting in scintillator arrays

NASA Astrophysics Data System (ADS)

Bisplinghoff, J.; Bollmann, R.; Cloth, P.; Dohrmann, F.; Dorner, G.; Drüke, V.; Ernst, J.; Eversheim, P. D.; Filges, D.; Gasthuber, M.; Gebel, R.; Groβ, A.; Groβ-Hardt, R.; Hinterberger, F.; Jahn, R.; Kühl, L.; Lahr, U.; Langkau, R.; Lippert, G.; Mayer-Kuckuk, T.; Maschuw, R.; Mertler, G.; Metsch, B.; Mosel, F.; Paetz gen. Schieck, H.; Petry, H. R.; Prasuhn, D.; Przewoski, B. v.; Rohdjeβ, H.; Rosendaal, D.; Rossen, P. v.; Scheid, H.; Schirm, N.; Schwandt, F.; Scobel, W.; Sprute, L.; Stein, H.; Theis, D.; Weber, J.; Wiedmann, W.; Woller, K.; Ziegler, R.; EDDA Collaboration

1993-05-01

A novel detector design of overlapping plastic scintillator elements in cylindrical geometry has been developed for detection of low multiplicity events of fast protons and other light charged particles: each particle traversing the detector from the axis outwards will produce light in several elements. The relative amounts of energy deposited in those elements allow one to interpolate on the particle trajectory beyond the resolution given by the granularity. The detector covers the angular range 10° ≤ Θlab ≤ 72° and 0° ≤ ϕ ≤ 360° with an inner layer of scintillator bars of triangular cross section and an outer layer of rings. The material is BC408. Tests with minimum ionizing electron beams show that spatial resolutions of ΔΘlab ≈ 1.5° and Δϕ12 ≈ 1.5° (FWHM) can be obtained for electrons or proton pairs with energies in the GeV range. In the EDDA experiment the ultimate spatial resolution is then determined by the size of the interaction area rather than by the intrinsic pulse height resolution of the detector.

New estimates of extensive-air-shower energies on the basis of signals in scintillation detectors

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

Anyutin, N. V.; Dedenko, L. G., E-mail: ddn@dec1.sinp.msu.ru; Roganova, T. M.

New formulas for estimating the energy of inclined extensive air showers (EASs) on the basis of signals in detectors by means of an original method and detailed tables of signals induced in scintillation detectors by photons, electrons, positrons, and muons and calculated with the aid of the GEANT4 code package were proposed in terms of the QGSJETII-04, EPOS LHC, and GHEISHA models. The parameters appearing in the proposed formulas were calculated by employing the CORSIKA code package. It is shown that, for showers of zenith angles in the range of 20◦–45◦, the standard constant-intensity-cut method, which is used to interpretmore » data from the Yakutsk EAS array, overestimates the shower energy by a factor of 1.2 to 1.5. It is proposed to employ the calculated VEM (Vertical Equivalent Muon) signal units of 10.8 and 11.4 MeV for, respectively, ground-based and underground scintillation detectors and to take into account the dependence of signals on the azimuthal angle of the detector position and fluctuations in the development of showers.« less

A new array for the study of ultra high energy gamma-ray sources

NASA Technical Reports Server (NTRS)

Brooke, G.; Lambert, A.; Ogden, P. A.; Patel, M.; Ferrett, J. C.; Reid, R. J. O.; Watson, A. A.; West, A. A.

1985-01-01

The design and operation of a 32 x 1 10 to the 15th power sq m array of scintillation detectors for the detection of 10 to the 15th power eV cosmic rays is described with an expected angular resolution of 1 deg, thus improving the present signal/background ratio for gamma ray sources. Data are recorded on a hybrid CAMAC, an in-house system which uses a laser and Pockel-Cell arrangement to routinely calibrate the timing stability of the detectors.

A LYSO crystal array readout by silicon photomultipliers as compact detector for space applications

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

Kryemadhi, A.; Barner, L.; Grove, A.

Precise measurements of GeV range gamma rays help narrow down among var- ious gamma emission models and increase sensitivity for dark matter searches. Construction of precise as well as compact instruments requires detectors with high efficiency, high stopping power, excellent energy resolution, and excellent angular resolution. Fast and bright crystal scintillators coupled with small foot- print photo-detectors are suitable candidates. We prototyped a detector array consisting of four LYSO crystals where each crystal is read out by a 2x2 SensL ArrayJ60035 silicon photomultipliers. The LYSO crystals were chosen because of their good light yield, fast decay time, demonstrated radiation hardness,more » and small radiation length. Here, we used the silicon photomultiplier arrays as photo- detectors because of their small size, simple readout, low voltage operation, and immunity to magnetic elds. We also studied the detector performance in the energy range of interest by exposing it to 2-16 GeV particles produced at the Test Beam Facility of Fermi National Accelerator Laboratory.« less

A LYSO crystal array readout by silicon photomultipliers as compact detector for space applications

DOE PAGES

Kryemadhi, A.; Barner, L.; Grove, A.; ...

2017-10-31

Precise measurements of GeV range gamma rays help narrow down among var- ious gamma emission models and increase sensitivity for dark matter searches. Construction of precise as well as compact instruments requires detectors with high efficiency, high stopping power, excellent energy resolution, and excellent angular resolution. Fast and bright crystal scintillators coupled with small foot- print photo-detectors are suitable candidates. We prototyped a detector array consisting of four LYSO crystals where each crystal is read out by a 2x2 SensL ArrayJ60035 silicon photomultipliers. The LYSO crystals were chosen because of their good light yield, fast decay time, demonstrated radiation hardness,more » and small radiation length. Here, we used the silicon photomultiplier arrays as photo- detectors because of their small size, simple readout, low voltage operation, and immunity to magnetic elds. We also studied the detector performance in the energy range of interest by exposing it to 2-16 GeV particles produced at the Test Beam Facility of Fermi National Accelerator Laboratory.« less

Characterization of EJ-200 plastic scintillators as active background shield for cosmogenic radiation

NASA Astrophysics Data System (ADS)

Tkaczyk, A. H.; Saare, H.; Ipbüker, C.; Schulte, F.; Mastinu, P.; Paepen, J.; Pedersen, B.; Schillebeeckx, P.; Varasano, G.

2018-02-01

This paper describes the characterization of commercially available plastic scintillation detectors to be used as an active shield or veto system to reduce the neutron background resulting from atmospheric muon interactions in low-level nuclear waste assay systems. The shield consists of an array of scintillation detectors surrounding a neutron detection system. Scintillation detectors with different thicknesses are characterized for their response to gamma rays, neutrons, and muons. Response functions to gamma rays were determined and measured in the energy range from 0.6 MeV to 6.0 MeV using radionuclide sources. Neutron response functions were derived from results of time-of-flight measurements at the Van de Graaff accelerator of the INFN Legnaro and from measurements with quasi mono-energetic neutron beams produced at the Van de Graaff accelerator of the JRC Geel. From these data, the light output and resolution functions for protons and electrons were derived. The response to muons was verified by background measurements, i.e. without the presence of any neutron or gamma source. It was found that the muon peak is more pronounced when the detectors are placed horizontally. The results indicate that a scintillator with a minimum thickness of 20 mm is needed to separate events due to atmospheric muons from natural gamma ray background, and contributions due to neutron production in nuclear waste based on only the total energy deposition in the detector. In addition, it was shown that muons can be identified with a coincidence pattern when the detectors are stacked. The effectiveness of the proposed system was demonstrated based on muon induced spallation reactions in a lead sample.

Silicon photomultipliers for scintillating trackers

NASA Astrophysics Data System (ADS)

Rabaioli, S.; Berra, A.; Bolognini, D.; Bonvicini, V.; Bosisio, L.; Ciano, S.; Iugovaz, D.; Lietti, D.; Penzo, A.; Prest, M.; Rashevskaya, I.; Reia, S.; Stoppani, L.; Vallazza, E.

2012-12-01

In recent years, silicon photomultipliers (SiPMs) have been proposed as a new kind of readout device for scintillating detectors in many experiments. A SiPM consists of a matrix of parallel-connected pixels, which are independent photon counters working in Geiger mode with very high gain (∼106). This contribution presents the use of an array of eight SiPMs (manufactured by FBK-irst) for the readout of a scintillating bar tracker (a small size prototype of the Electron Muon Ranger detector for the MICE experiment). The performances of the SiPMs in terms of signal to noise ratio, efficiency and time resolution will be compared to the ones of a multi-anode photomultiplier tube (MAPMT) connected to the same bars. Both the SiPMs and the MAPMT are interfaced to a VME system through a 64 channel MAROC ASIC.

Liquid argon scintillation detection utilizing wavelength-shifting plates and light guides

NASA Astrophysics Data System (ADS)

Howard, B.

2018-02-01

In DUNE, the event timing provided by the detection of the relatively prompt scintillation photons will improve spatial resolution in the drift direction of the time-projection chamber (TPC) and is especially useful for non-beam physics topics such as supernova neutrinos and nucleon decay. The baseline design for the first 10kt single phase TPC fits the photon detector system in the natural gap between the wire planes of adjacent TPC volumes. A prototype photon detector design utilizes wavelength-shifter coated plates to convert the vacuum ultraviolet scintillation light to the optical and commercially-produced wavelength-shifting light guides to trap some of this light and transport it to an array of silicon photomultipliers at the end. This system and the testing performed to characterize the system and determine the efficiency are discussed.

Liquid Argon Scintillation Detection Utilizing Wavelength-Shifting Plates and Light Guides

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

Howard, B.

In DUNE, the event timing provided by the detection of the relatively prompt scintillation photons will improve spatial resolution in the drift direction of the time-projection chamber (TPC) and is especially useful for non-beam physics topics such as supernova neutrinos and nucleon decay. The baseline design for the first 10kt single phase TPC fits the photon detector system in the natural gap between the wire planes of adjacent TPC volumes. A prototype photon detector design utilizes wavelength-shifter coated plates to convert the vacuum ultraviolet scintillation light to the optical and commercially-produced wavelength-shifting light guides to trap some of this lightmore » and transport it to an array of silicon photomultipliers at the end. This system and the testing performed to characterize the system and determine the efficiency are discussed.« less

DESCANT and β-delayed neutron measurements at TRIUMF

NASA Astrophysics Data System (ADS)

Bildstein, V.; Garrett, P. E.; Ashley, S. F.; Ball, G. C.; Bianco, L.; Bandyopadhyay, D.; Bangay, J.; Crider, B. P.; Demand, G.; Deng, G.; Dillmann, I.; Finlay, A.; Garnsworthy, A. B.; Hackman, G.; Hadinia, B.; Krücken, R.; Leach, K. G.; Martin, J.-P.; McEllistrem, M. T.; Pearson, C. J.; Peters, E. E.; Prados-Estévez, F. M.; Radich, A.; Sarazin, F.; Sumithrarachchi, C.; Svensson, C. E.; Vanhoy, J. R.; Wong, J.; Yates, S. W.

2015-05-01

The DESCANT array (Deuterated Scintillator Array for Neutron Tagging) consists of up to 70 detectors, each filled with approximately 2 liters of deuterated benzene. This scintillator material o_ers pulse-shape discrimination (PSD) capabilities to distinguish between neutrons and γ-rays interacting with the scintillator material. In addition, the anisotropic nature of n - d scattering allows for the determination of the neutron energy spectrum directly from the pulse height spectrum, complementing the traditional time-of-flight (ToF) information. DESCANT can be coupled either to the TIGRESS (TRIUMF-ISAC Gamma-Ray Escape Suppressed Spectrometer) γ-ray spectrometer [1] located in the ISAC-II [2] hall of TRIUMF for in-beam experiments, or to the GRIFFIN (Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei) γ-ray spectrometer [3] located in the ISAC-I hall of TRIUMF for decay spectroscopy experiments.

Monte Carlo simulation of a very high resolution thermal neutron detector composed of glass scintillator microfibers.

PubMed

Song, Yushou; Conner, Joseph; Zhang, Xiaodong; Hayward, Jason P

2016-02-01

In order to develop a high spatial resolution (micron level) thermal neutron detector, a detector assembly composed of cerium doped lithium glass microfibers, each with a diameter of 1 μm, is proposed, where the neutron absorption location is reconstructed from the observed charged particle products that result from neutron absorption. To suppress the cross talk of the scintillation light, each scintillating fiber is surrounded by air-filled glass capillaries with the same diameter as the fiber. This pattern is repeated to form a bulk microfiber detector. On one end, the surface of the detector is painted with a thin optical reflector to increase the light collection efficiency at the other end. Then the scintillation light emitted by any neutron interaction is transmitted to one end, magnified, and recorded by an intensified CCD camera. A simulation based on the Geant4 toolkit was developed to model this detector. All the relevant physics processes including neutron interaction, scintillation, and optical boundary behaviors are simulated. This simulation was first validated through measurements of neutron response from lithium glass cylinders. With good expected light collection, an algorithm based upon the features inherent to alpha and triton particle tracks is proposed to reconstruct the neutron reaction position in the glass fiber array. Given a 1 μm fiber diameter and 0.1mm detector thickness, the neutron spatial resolution is expected to reach σ∼1 μm with a Gaussian fit in each lateral dimension. The detection efficiency was estimated to be 3.7% for a glass fiber assembly with thickness of 0.1mm. When the detector thickness increases from 0.1mm to 1mm, the position resolution is not expected to vary much, while the detection efficiency is expected to increase by about a factor of ten. Copyright © 2015 Elsevier Ltd. All rights reserved.

QBeRT: an innovative instrument for qualification of particle beam in real-time

NASA Astrophysics Data System (ADS)

Gallo, G.; Lo Presti, D.; Bonanno, D. L.; Longhitano, F.; Bongiovanni, D. G.; Reito, S.; Randazzo, N.; Leonora, E.; Sipala, V.; Tommasino, F.

2016-11-01

This paper describes an innovative beam diagnostic and monitoring system composed of a position sensitive detector and a residual range detector, based on scintillating optical fiber and on an innovative read-out strategy and reconstruction algorithm. The position sensitive detector consists of four layers of pre-aligned and juxtaposed scintillating fibres arranged to form two identical overlying and orthogonal planes. The 500 μm square section fibres are optically coupled to two Silicon Photomultiplier arrays using a channel reduction system patented by the Istituto Nazionale di Fisica Nucleare. The residual range detector is a stack of sixty parallel layers of the same fibres used in the position detector, each of which is optically coupled to a channel of Silicon Photomultiplier array by wavelength shifting fibres. The sensitive area of the two detectors is 9 × 9 cm2. After being fully characterized at CATANA proton therapy facility, the performance of the prototypes was tested during last year also at TIFPA proton irradiation facility. The unique feature of these detectors is the possibility to work in imaging conditions (e.g. a particle at a time up to 106 particles per second) and in therapy conditions up to 109 particles per second. The combined use of the two detectors, in imaging conditions, as an example of application, allows the particle radiography of an object. In therapy conditions, in particular, the system measures the position, the profiles, the energy and the fluence of the beam.

Development of New High Resolution Neutron Detector

NASA Astrophysics Data System (ADS)

Mostella, L. D., III; Rajabali, M.; Loureiro, D. P.; Grzywacz, R.

2017-09-01

Beta-delayed neutron emission is a prevalent form of decay for neutron-rich nuclei. This occurs when an unstable nucleus undergoes beta decay, but produces a daughter nucleus in an excited state above the neutron separation energy. The daughter nucleus then de-excites by ejecting one or more neutrons. We wish to map the states from which these nuclei decay via neutron spectroscopy using NEXT, a new high resolution neutron detector. NEXT utilizes silicon photomultipliers and 6 mm thick pulse-shape discriminating plastic scintillators, allowing for smaller and more compact modular geometries in the NEXT array. Timing measurements for the detector were performed and a resolution of 893 ps (FWHM) has been achieved so far. Aspects of the detector that were investigated and will be presented here include scintillator geometry, wrapping materials, fitting functions for the digitized signals, and electronic components coupled to the silicon photomultipliers for signal shaping.

Shifting scintillator neutron detector

DOEpatents

Clonts, Lloyd G; Cooper, Ronald G; Crow, Jr., Morris Lowell; Hannah, Bruce W; Hodges, Jason P; Richards, John D; Riedel, Richard A

2014-03-04

Provided are sensors and methods for detecting thermal neutrons. Provided is an apparatus having a scintillator for absorbing a neutron, the scintillator having a back side for discharging a scintillation light of a first wavelength in response to the absorbed neutron, an array of wavelength-shifting fibers proximate to the back side of the scintillator for shifting the scintillation light of the first wavelength to light of a second wavelength, the wavelength-shifting fibers being disposed in a two-dimensional pattern and defining a plurality of scattering plane pixels where the wavelength-shifting fibers overlap, a plurality of photomultiplier tubes, in coded optical communication with the wavelength-shifting fibers, for converting the light of the second wavelength to an electronic signal, and a processor for processing the electronic signal to identify one of the plurality of scattering plane pixels as indicative of a position within the scintillator where the neutron was absorbed.

Highlights from the Telescope Array Experiment

NASA Astrophysics Data System (ADS)

Sagawa, H.

2014-10-01

The Telescope Array (TA) is the largest experiment in the Northern Hemisphere currently studying the origin and nature of ultra-high-energy cosmic rays above ˜1018 eV by measuring their energy spectrum, mass composition, and arrival directions. It is located in the western desert of central Utah, USA. The TA detector consists of a surface array of 507 scintillation counters, deployed on a square grid of 1.2-km spacing that covers approximately 700 km2, and 38 fluorescence telescopes located at three sites looking over the surface array. The TA commenced hybrid observation with both sets of detectors in 2008. Here, we present recent results from these 5 years of data and outline our ongoing and near future plans.

DESCANT - The DEuterated SCintillator Array for Neutron Tagging

NASA Astrophysics Data System (ADS)

Bildstein, Vinzenz; Garrett, P. E.; Bandyopadhay, D.; Bangay, J.; Bianco, L.; Demand, G.; Hadinia, B.; Leach, K. G.; Sumithrarachchi, C.; Turko, J.; Wong, J.; Ashley, S. F.; Crider, B. P.; McEllistrem, M. T.; Peters, E. E.; Prados-Estévez, F. M.; Yates, S. W.; Vanhoy, J. R.; Ball, G. C.; Bishop, D. P.; Garnsworthy, A. B.; Hackman, G.; Pearson, C. J.; Shaw, B.; Saran, F.

2016-09-01

The DESCANT array at TRIUMF is designed to detect neutrons from RIB experiments. DESCANT is composed of 70 close-packed deuterated organic liquid scintillators coupled to digital fast read-out ADC modules. This configuration will permit online pulse-shape discrimination between neutron and γ-ray events. A prototype detector has been tested with monoenergetic neutrons at the accelerator laboratory of the University of Kentucky. A first commissioning experiment of the full array, using the decay of 145-146Cs, will be performed in August 2016. The results of the tests and a preliminary analysis of the commissioning experiment will be presented. Work supported by the Canada Foundation for Innovation, the Natural Sciences and Engineering Research Council of Canada, the National Research Council of Canada and the Canadian Research Chairs program.

Modeling Photo-multiplier Gain and Regenerating Pulse Height Data for Application Development

NASA Astrophysics Data System (ADS)

Aspinall, Michael D.; Jones, Ashley R.

2018-01-01

Systems that adopt organic scintillation detector arrays often require a calibration process prior to the intended measurement campaign to correct for significant performance variances between detectors within the array. These differences exist because of low tolerances associated with photo-multiplier tube technology and environmental influences. Differences in detector response can be corrected for by adjusting the supplied photo-multiplier tube voltage to control its gain and the effect that this has on the pulse height spectra from a gamma-only calibration source with a defined photo-peak. Automated methods that analyze these spectra and adjust the photo-multiplier tube bias accordingly are emerging for hardware that integrate acquisition electronics and high voltage control. However, development of such algorithms require access to the hardware, multiple detectors and calibration source for prolonged periods, all with associated constraints and risks. In this work, we report on a software function and related models developed to rescale and regenerate pulse height data acquired from a single scintillation detector. Such a function could be used to generate significant and varied pulse height data that can be used to integration-test algorithms that are capable of automatically response matching multiple detectors using pulse height spectra analysis. Furthermore, a function of this sort removes the dependence on multiple detectors, digital analyzers and calibration source. Results show a good match between the real and regenerated pulse height data. The function has also been used successfully to develop auto-calibration algorithms.

Conceptual design of the early implementation of the NEutron Detector Array (NEDA) with AGATA

NASA Astrophysics Data System (ADS)

Hüyük, Tayfun; Di Nitto, Antonio; Jaworski, Grzegorz; Gadea, Andrés; Javier Valiente-Dobón, José; Nyberg, Johan; Palacz, Marcin; Söderström, Pär-Anders; Jose Aliaga-Varea, Ramon; de Angelis, Giacomo; Ataç, Ayşe; Collado, Javier; Domingo-Pardo, Cesar; Egea, Francisco Javier; Erduran, Nizamettin; Ertürk, Sefa; de France, Gilles; Gadea, Rafael; González, Vicente; Herrero-Bosch, Vicente; Kaşkaş, Ayşe; Modamio, Victor; Moszynski, Marek; Sanchis, Enrique; Triossi, Andrea; Wadsworth, Robert

2016-03-01

The NEutron Detector Array (NEDA) project aims at the construction of a new high-efficiency compact neutron detector array to be coupled with large γ-ray arrays such as AGATA. The application of NEDA ranges from its use as selective neutron multiplicity filter for fusion-evaporation reaction to a large solid angle neutron tagging device. In the present work, possible configurations for the NEDA coupled with the Neutron Wall for the early implementation with AGATA has been simulated, using Monte Carlo techniques, in order to evaluate their performance figures. The goal of this early NEDA implementation is to improve, with respect to previous instruments, efficiency and capability to select multiplicity for fusion-evaporation reaction channels in which 1, 2 or 3 neutrons are emitted. Each NEDA detector unit has the shape of a regular hexagonal prism with a volume of about 3.23l and it is filled with the EJ301 liquid scintillator, that presents good neutron- γ discrimination properties. The simulations have been performed using a fusion-evaporation event generator that has been validated with a set of experimental data obtained in the 58Ni + 56Fe reaction measured with the Neutron Wall detector array.

The AMIGA enhancement of the Pierre Auger Observatory

NASA Astrophysics Data System (ADS)

Maldera, S.

2014-06-01

The AMIGA (Auger Muons and Infill for the Ground Array) enhancement of the Auger Surface Detector consists of a 23.5 km2 infill area instrumented with water-Cherenkov detector stations accompanied by 30 m2 of scintillator counters, buried 2.3 m underground. The spacing of 750 m between the surface detectors extends the energy range as low as 3 × 1017 eV, thus allowing the study of the energy region where the transition between galactic and extra-galactic cosmic rays is expected to take place. We describe the reconstruction of the events observed with the infill water-Cherenkov detector array and the derived energy spectrum. We also discuss the basic properties of the muon detector modules obtained from measurements and tests during the construction phase and from the first data in the field.

An algorithm for automatic crystal identification in pixelated scintillation detectors using thin plate splines and Gaussian mixture models

NASA Astrophysics Data System (ADS)

Schellenberg, Graham; Stortz, Greg; Goertzen, Andrew L.

2016-02-01

A typical positron emission tomography detector is comprised of a scintillator crystal array coupled to a photodetector array or other position sensitive detector. Such detectors using light sharing to read out crystal elements require the creation of a crystal lookup table (CLUT) that maps the detector response to the crystal of interaction based on the x-y position of the event calculated through Anger-type logic. It is vital for system performance that these CLUTs be accurate so that the location of events can be accurately identified and so that crystal-specific corrections, such as energy windowing or time alignment, can be applied. While using manual segmentation of the flood image to create the CLUT is a simple and reliable approach, it is both tedious and time consuming for systems with large numbers of crystal elements. In this work we describe the development of an automated algorithm for CLUT generation that uses a Gaussian mixture model paired with thin plate splines (TPS) to iteratively fit a crystal layout template that includes the crystal numbering pattern. Starting from a region of stability, Gaussians are individually fit to data corresponding to crystal locations while simultaneously updating a TPS for predicting future Gaussian locations at the edge of a region of interest that grows as individual Gaussians converge to crystal locations. The algorithm was tested with flood image data collected from 16 detector modules, each consisting of a 409 crystal dual-layer offset LYSO crystal array readout by a 32 pixel SiPM array. For these detector flood images, depending on user defined input parameters, the algorithm runtime ranged between 17.5-82.5 s per detector on a single core of an Intel i7 processor. The method maintained an accuracy above 99.8% across all tests, with the majority of errors being localized to error prone corner regions. This method can be easily extended for use with other detector types through adjustment of the initial template model used.

NeutronSTARS: A segmented neutron and charged particle detector for low-energy reaction studies

DOE PAGES

Akindele, O. A.; Casperson, R. J.; Wang, B. S.; ...

2017-08-10

NeutronSTARS (Neutron-S ilicon T elescope A rray for R eaction S tudies) consists of 2.2-tons of gadolinium-doped liquid scintillator for neutron detection and large area silicon detectors for charged particle identification. This detector array is intended for low-energy-nuclear-reaction measurements that result in the emission of neutrons such as and fission. This paper describes the NeutronSTARS experimental setup, calibration, and the array’s response to neutral and charged particles.

Nuclear Science Symposium, 23rd, Scintillation and Semiconductor Counter Symposium, 15th, and Nuclear Power Systems Symposium, 8th, New Orleans, La., October 20-22, 1976, Proceedings

NASA Technical Reports Server (NTRS)

Wagner, L. J.

1977-01-01

The volume includes papers on semiconductor radiation detectors of various types, components of radiation detection and dosimetric systems, digital and microprocessor equipment in nuclear industry and science, and a wide variety of applications of nuclear radiation detectors. Semiconductor detectors of X-rays, gamma radiation, heavy ions, neutrons, and other nuclear particles, plastic scintillator arrays, drift chambers, spark wire chambers, and radiation dosimeter systems are reported on. Digital and analog conversion systems, digital data and control systems, microprocessors, and their uses in scientific research and nuclear power plants are discussed. Large-area imaging and biomedical nucleonic instrumentation, nuclear power plant safeguards, reactor instrumentation, nuclear power plant instrumentation, space instrumentation, and environmental instrumentation are dealt with. Individual items are announced in this issue.

Simulation, optimization and testing of a novel high spatial resolution X-ray imager based on Zinc Oxide nanowires in Anodic Aluminium Oxide membrane using Geant4

NASA Astrophysics Data System (ADS)

Esfandi, F.; Saramad, S.

2015-07-01

In this work, a new generation of scintillator based X-ray imagers based on ZnO nanowires in Anodized Aluminum Oxide (AAO) nanoporous template is characterized. The optical response of ordered ZnO nanowire arrays in porous AAO template under low energy X-ray illumination is simulated by the Geant4 Monte Carlo code and compared with experimental results. The results show that for 10 keV X-ray photons, by considering the light guiding properties of zinc oxide inside the AAO template and suitable selection of detector thickness and pore diameter, the spatial resolution less than one micrometer and the detector detection efficiency of 66% are accessible. This novel nano scintillator detector can have many advantages for medical applications in the future.

High quantum efficiency megavoltage imaging with thick scintillator detectors for image guided radiation therapy

NASA Astrophysics Data System (ADS)

Gopal, Arun

In image guided radiation therapy (IGRT), imaging devices serve as guidance systems to aid patient set-up and tumor volume localization. Traditionally, 2-D megavoltage x-ray imagers, referred to as electronic portal imaging devices (EPIDs), have been used for planar target localization, and have recently been extended to perform 3-D volumetric reconstruction via cone-beam computed tomography (CBCT). However, current EPIDs utilize thin and inefficient phosphor screen detectors and are subsequently limited by poor soft tissue visualization, which limits their use for CBCT. Therefore, the use of thick scintillation media as megavoltage x-ray detectors for greater x-ray sensitivity and enhanced image quality has recently been of significant interest. In this research, two candidates for thick scintillators: CsI(Tl) and terbium doped scintillation glass were investigated in separate imaging configurations. In the first configuration, a thick scintillation crystal (TSC) consisting of a thick, monolithic slab of CsI(Tl) was coupled to a mirror-lens-camera system. The second configuration is based on a fiber-optic scintillation glass array (FOSGA), wherein the scintillation glass is drawn into long fiber-optic conduits, inserted into a grid-type housing constructed out of polymer-tungsten alloy, and coupled to an array of photodiodes for digital read-out. The imaging prototypes were characterized using theoretical studies and imaging measurements to obtain fundamental metrics of imaging performance. Spatial resolution was measured based on a modulation transfer function (MTF), noise was evaluated in terms of a noise power spectrum (NPS), and overall contrast was characterized in the form of detective quantum efficiency (DQE). The imaging studies were used to optimize the TSC and FOSGA imagers and propose prototype configurations for order-of-magnitude improvements in overall image quality. In addition, a fast and simple technique was developed to measure the MTF, NPS, and DQE metrics for clinical EPID and CBCT systems based on a novel adaptation of a traditional line-pair resolution bar-pattern. This research provides two significant benefits to radiotherapy: the characterization of a new generation of thick scintillator based megavoltage x-ray imagers for CBCT based IGRT, and the novel adaptation of fundamental imaging metrics from imaging research to routine clinical performance monitoring.

Development of a hard x-ray focal plane compton polarimeter: a compact polarimetric configuration with scintillators and Si photomultipliers

NASA Astrophysics Data System (ADS)

Chattopadhyay, T.; Vadawale, S. V.; Goyal, S. K.; Mithun, N. P. S.; Patel, A. R.; Shukla, R.; Ladiya, T.; Shanmugam, M.; Patel, V. R.; Ubale, G. P.

2016-02-01

X-ray polarization measurement of cosmic sources provides two unique parameters namely degree and angle of polarization which can probe the emission mechanism and geometry at close vicinity of the compact objects. Specifically, the hard X-ray polarimetry is more rewarding because the sources are expected to be intrinsically highly polarized at higher energies. With the successful implementation of Hard X-ray optics in NuSTAR, it is now feasible to conceive Compton polarimeters as focal plane detectors. Such a configuration is likely to provide sensitive polarization measurements in hard X-rays with a broad energy band. We are developing a focal plane hard X-ray Compton polarimeter consisting of a plastic scintillator as active scatterer surrounded by a cylindrical array of CsI(Tl) scintillators. The scatterer is 5 mm diameter and 100 mm long plastic scintillator (BC404) viewed by normal PMT. The photons scattered by the plastic scatterer are collected by a cylindrical array of 16 CsI(Tl) scintillators (5 mm × 5 mm × 150 mm) which are read by Si Photomultiplier (SiPM). Use of the new generation SiPMs ensures the compactness of the instrument which is essential for the design of focal plane detectors. The expected sensitivity of such polarimetric configuration and complete characterization of the plastic scatterer, specially at lower energies have been discussed in [11, 13]. In this paper, we characterize the CsI(Tl) absorbers coupled to SiPM. We also present the experimental results from the fully assembled configuration of the Compton polarimeter.

Status and performance of the AS array of the Tibet AS sub. gamma. experiment

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

Amenomori, M.; Bai, Z.W.; Cao, Z.

1991-04-05

The Tibet AS{gamma} experiment, which has started since January, 1990, is located at an altitude of 4,300m at Yangbaging in Tibet, China (90.5{degree} E, 301{degree} N). The air-shower array is composed of 49 scintillation counters for fast timing (FT), each counter having an area of 0.5 m{sup 2}, in a grid pattern with a spacing of 15 m and 16 density detectors. The density detectors surrounding the FT detectors are planned to select the showers of which core are inside the FT array. For the constant and continuous opeation, the system for laser calibration, the ADC,TDC module calibration and themore » power check system were installed. A Rb clock is used for the phase analysis of {gamma}-rays.« less

Silicon photomultipliers in scintillation detectors used for gamma ray energies up to 6.1 MeV

NASA Astrophysics Data System (ADS)

Grodzicka-Kobylka, M.; Szczesniak, T.; Moszyński, M.; Swiderski, L.; Szawłowski, M.

2017-12-01

Majority of papers concerning scintillation detectors with light readout by means of silicon photomultipliers refer to nuclear medicine or radiation monitoring devices where energy of detected gamma rays do not exceed 2 MeV. Detection of gamma radiation with higher energies is of interest to e.g. high energy physics and plasma diagnostics. The aim of this paper is to study applicability (usefulness) of SiPM light readout in detection of gamma rays up to 6.1 MeV in combination with various scintillators. The reported measurements were made with 3 samples of one type of Hamamatsu TSV (Through-Silicon Via technology) MPPC arrays. These 4x4 channel arrays have a 50 × 50 μm2 cell size and 12 × 12 mm2 effective active area. The following scintillators were used: CeBr3, NaI:Tl, CsI:Tl. During all the tests detectors were located in a climatic chamber. The studies are focused on optimization of the MPPC performance for practical use in detection of high energy gamma rays. The optimization includes selection of the optimum operating voltage in respect to the required energy resolution, dynamic range, linearity and pulse amplitude. The presented temperature tests show breakdown voltage dependence on the temperature change and define requirements for a power supply and gain stabilization method. The energy spectra for energies between 511 keV and 6.1 MeV are also presented and compared with data acquired with a classic photomultiplier XP5212B readout. Such a comparison allowed study of nonlinearity of the tested MPPCs, correction of the energy spectra and proper analysis of the energy resolution.

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

NASA Astrophysics Data System (ADS)

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

2013-09-01

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

Design and simulation of a novel method for determining depth-of-interaction in a PET scintillation crystal array using a single-ended readout by a multi-anode PMT

NASA Astrophysics Data System (ADS)

Ito, Mikiko; Lee, Jae Sung; Park, Min-Jae; Sim, Kwang-Souk; Jong Hong, Seong

2010-07-01

PET detectors with depth-of-interaction (DOI) encoding capability allow high spatial resolution and high sensitivity to be achieved simultaneously. To obtain DOI information from a mono-layer array of scintillation crystals using a single-ended readout, the authors devised a method based on light spreading within a crystal array and performed Monte Carlo simulations with individual scintillation photon tracking to prove the concept. A scintillation crystal array model was constructed using a grid method. Conventional grids are constructed using comb-shaped reflector strips with rectangular teeth to isolate scintillation crystals optically. However, the authors propose the use of triangularly shaped teeth, such that scintillation photons spread only in the x-direction in the upper halves of crystals and in the y-direction in lower halves. DOI positions can be estimated by considering the extent of two-dimensional light dispersion, which can be determined from the multiple anode outputs of a position-sensitive PMT placed under the crystal array. In the main simulation, a crystal block consisting of a 29 × 29 array of 1.5 mm × 1.5 mm × 20 mm crystals and a multi-anode PMT with 16 × 16 pixels were used. The effects of crystal size and non-uniform PMT output gain were also explored by simulation. The DOI resolution estimated for 1.5 × 1.5 × 20 mm3 crystals was 2.16 mm on average. Although the flood map was depth dependent, each crystal was well identified at all depths when a corner of the crystal array was irradiated with 511 keV gamma rays (peak-to-valley ratio ~9:1). DOI resolution was better than 3 mm up to a crystal length of 28 mm with a 1.5 × 1.5 mm2 or 2.0 × 2.0 mm2 crystal surface area. The devised light-sharing method allowed excellent DOI resolutions to be obtained without the use of dual-ended readout or multiple crystal arrays.

A novel fast-neutron tomography system based on a plastic scintillator array and a compact D-D neutron generator.

PubMed

Adams, Robert; Zboray, Robert; Prasser, Horst-Michael

2016-01-01

Very few experimental imaging studies using a compact neutron generator have been published, and to the knowledge of the authors none have included tomography results using multiple projection angles. Radiography results with a neutron generator, scintillator screen, and camera can be seen in Bogolubov et al. (2005), Cremer et al. (2012), and Li et al. (2014). Comparable results with a position-sensitive photomultiplier tube can be seen in Popov et al. (2011). One study using an array of individual fast neutron detectors in the context of cargo scanning for security purposes is detailed in Eberhardt et al. (2005). In that case, however, the emphasis was on very large objects with a resolution on the order of 1cm, whereas this study focuses on less massive objects and a finer spatial resolution. In Andersson et al. (2014) three fast neutron counters and a D-T generator were used to perform attenuation measurements of test phantoms. Based on the axisymmetry of the test phantoms, the single-projection information was used to calculate radial attenuation distributions of the object, which was compared with the known geometry. In this paper a fast-neutron tomography system based on an array of individual detectors and a purpose-designed compact D-D neutron generator is presented. Each of the 88 detectors consists of a plastic scintillator read out by two Silicon photomultipliers and a dedicated pulse-processing board. Data acquisition for all channels was handled by four single-board microcontrollers. Details of the individual detector design and testing are elaborated upon. Using the complete array, several fast-neutron images of test phantoms were reconstructed, one of which was compared with results using a Co-60 gamma source. The system was shown to be capable of 2mm resolution, with exposure times on the order of several hours per reconstructed tomogram. Details about these measurements and the analysis of the reconstructed images are given, along with a discussion of the capabilities of the system and its outlook. Copyright © 2015 Elsevier Ltd. All rights reserved.

Prototype muon detectors for the AMIGA component of the Pierre Auger Observatory

DOE PAGES

Aab, Alexander

2016-02-17

AMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of the Pierre Auger Observatory to extend its range of detection and to directly measure the muon content of the particle showers. It consists of an infill of surface water-Cherenkov detectors accompanied by buried scintillator detectors used for muon counting. The main objectives of the AMIGA engineering array, referred to as the Unitary Cell, are to identify and resolve all engineering issues as well as to understand the muon-number counting uncertainties related to the design of the detector. The mechanical design, fabrication and deployment processes of the muonmore » counters of the Unitary Cell are described in this document. These muon counters modules comprise sealed PVC casings containing plastic scintillation bars, wavelength-shifter optical fibers, 64 pixel photomultiplier tubes, and acquisition electronics. The modules are buried approximately 2.25 m below ground level in order to minimize contamination from electromagnetic shower particles. The mechanical setup, which allows access to the electronics for maintenance, is also described in addition to tests of the modules' response and integrity. As a result, the completed Unitary Cell has measured a number of air showers of which a first analysis of a sample event is included here.« less

SU-C-201-01: Investigation of the Effects of Scintillator Surface Treatment On Light Output Measurements with SiPM Detectors

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

Valenciaga, Y; Prout, D; Chatziioannou, A

2015-06-15

Purpose: To examine the effect of different scintillator surface treatments (BGO crystals) on the fraction of scintillation photons that exit the crystal and reach the photodetector (SiPM). Methods: Positron Emission Tomography is based on the detection of light that exits scintillator crystals, after annihilation photons deposit energy inside these crystals. A considerable fraction of the scintillation light gets trapped or absorbed after going through multiple internal reflections on the interfaces surrounding the crystals. BGO scintillator crystals generate considerably less scintillation light than crystals made of LSO and its variants. Therefore, it is crucial that the small amount of light producedmore » by BGO exits towards the light detector. The surface treatment of scintillator crystals is among the factors affecting the ability of scintillation light to reach the detectors. In this study, we analyze the effect of different crystal surface treatments on the fraction of scintillation light that is detected by the solid state photodetector (SiPM), once energy is deposited inside a BGO crystal. Simulations were performed by a Monte Carlo based software named GATE, and validated by measurements from individual BGO crystals coupled to Philips digital-SiPM sensor (DPC-3200). Results: The results showed an increment in light collection of about 4 percent when only the exit face of the BGO crystal, is unpolished; compared to when all the faces are polished. However, leaving several faces unpolished caused a reduction of at least 10 percent of light output when the interaction occurs as far from the exit face of the crystal as possible compared to when it occurs very close to the exit face. Conclusion: This work demonstrates the advantages on light collection from leaving unpolished the exit face of BGO crystals. The configuration with best light output will be used to obtain flood images from BGO crystal arrays coupled to SiPM sensors.« less

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

NASA Astrophysics Data System (ADS)

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

2015-06-01

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

Development of a new scintillation-trigger detector for the MTV experiment using aluminum-metallized film tape

NASA Astrophysics Data System (ADS)

Sakamoto, Yuko; Ozaki, Sachi; Tanaka, Saki; Tanuma, Ryosuke; Yoshida, Tatsuru; Murata, Jiro

2014-09-01

A new type of trigger-scintillation counter array designed for the MTV experiment at TRIUMF-ISAC has been developed, using aluminum-metallized film tape for wrapping. The MTV experiment aims to perform the finest precision test of time reversal symmetry in nuclear beta decay. In that purpose, we search non-zero T-Violating transverse polarization of electrons emitted from polarized Li-8 nuclei. It uses a cylindrical drift chamber (CDC) as the main electron-tracking detector. The trigger-scintillation counter consists of 12-segmented 1 mm thick 300 mm long thin plastic scintillation counters. This counter is placed inside the CDC to generate a trigger signal. The required assembling precision of +-0.5 mm was a tricky point when we tried to use conventional total reflection mode. Indeed, produce an air-layer surrounding the scintillating bar to keep good light transmission was the main issue. For this reason, we tried to use a new wrapping material made of metallized-aluminum tape, which has a good mirror-like reflecting surface on both sides of the tape. Through this report, we will compare detection efficiency and light attenuation between conventional and new wrapping materials.

Imaging properties of pixellated scintillators with deep pixels

PubMed Central

Barber, H. Bradford; Fastje, David; Lemieux, Daniel; Grim, Gary P.; Furenlid, Lars R.; Miller, Brian W.; Parkhurst, Philip; Nagarkar, Vivek V.

2015-01-01

We have investigated the light-transport properties of scintillator arrays with long, thin pixels (deep pixels) for use in high-energy gamma-ray imaging. We compared 10×10 pixel arrays of YSO:Ce, LYSO:Ce and BGO (1mm × 1mm × 20 mm pixels) made by Proteus, Inc. with similar 10×10 arrays of LSO:Ce and BGO (1mm × 1mm × 15mm pixels) loaned to us by Saint-Gobain. The imaging and spectroscopic behaviors of these scintillator arrays are strongly affected by the choice of a reflector used as an inter-pixel spacer (3M ESR in the case of the Proteus arrays and white, diffuse-reflector for the Saint-Gobain arrays). We have constructed a 3700-pixel LYSO:Ce Prototype NIF Gamma-Ray Imager for use in diagnosing target compression in inertial confinement fusion. This system was tested at the OMEGA Laser and exhibited significant optical, inter-pixel cross-talk that was traced to the use of a single-layer of ESR film as an inter-pixel spacer. We show how the optical cross-talk can be mapped, and discuss correction procedures. We demonstrate a 10×10 YSO:Ce array as part of an iQID (formerly BazookaSPECT) imager and discuss issues related to the internal activity of 176Lu in LSO:Ce and LYSO:Ce detectors. PMID:26236070

Imaging properties of pixellated scintillators with deep pixels

NASA Astrophysics Data System (ADS)

Barber, H. Bradford; Fastje, David; Lemieux, Daniel; Grim, Gary P.; Furenlid, Lars R.; Miller, Brian W.; Parkhurst, Philip; Nagarkar, Vivek V.

2014-09-01

We have investigated the light-transport properties of scintillator arrays with long, thin pixels (deep pixels) for use in high-energy gamma-ray imaging. We compared 10x10 pixel arrays of YSO:Ce, LYSO:Ce and BGO (1mm x 1mm x 20 mm pixels) made by Proteus, Inc. with similar 10x10 arrays of LSO:Ce and BGO (1mm x 1mm x 15mm pixels) loaned to us by Saint-Gobain. The imaging and spectroscopic behaviors of these scintillator arrays are strongly affected by the choice of a reflector used as an inter-pixel spacer (3M ESR in the case of the Proteus arrays and white, diffuse-reflector for the Saint-Gobain arrays). We have constructed a 3700-pixel LYSO:Ce Prototype NIF Gamma-Ray Imager for use in diagnosing target compression in inertial confinement fusion. This system was tested at the OMEGA Laser and exhibited significant optical, inter-pixel cross-talk that was traced to the use of a single-layer of ESR film as an inter-pixel spacer. We show how the optical cross-talk can be mapped, and discuss correction procedures. We demonstrate a 10x10 YSO:Ce array as part of an iQID (formerly BazookaSPECT) imager and discuss issues related to the internal activity of 176Lu in LSO:Ce and LYSO:Ce detectors.

Neutron Capture Experiments Using the DANCE Array at Los Alamos

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

Dashdorj, D.; MonAme Scientific Research Center, Ulaanbaatar; Mitchell, G. E.

2009-03-31

The Detector for Advanced Neutron Capture Experiments (DANCE) is designed for neutron capture measurements on very small and/or radioactive targets. The DANCE array of 160 BaF{sub 2} scintillation detectors is located at the Lujan Center at the Los Alamos Neutron Science Center (LANSCE). Accurate measurements of neutron capture data are important for many current applications as well as for basic understanding of neutron capture. The gamma rays following neutron capture reactions have been studied by the time-of-flight technique using the DANCE array. The high granularity of the array allows measurements of the gamma-ray multiplicity. The gamma-ray multiplicities and energy spectramore » for different multiplicities can be measured and analyzed for spin and parity determination of the resolved resonances.« less

The UCD/FLWO extensive air shower array at Mt. Hopkins Arizona

NASA Astrophysics Data System (ADS)

Gillanders, G. H.; Fegan, D. J.; McKeown, P. K.; Weekes, T. C.

The design and operation of an extensive air shower (EAS) array being installed around the 10-m optical Cerenkov reflector at F.L. Whipple Observatory on Mt. Hopkins for high-energy gamma-ray astronomy are described. The advantages of an EAS array colocated with a Cerenkov facility at a mountain location are reviewed; the arrangement of the 13 1-sq m scintillation detectors in the array is indicated; the signal-processing and data-acquisition procedures are explained; and preliminary calibration data indicating an effective energy threshold of 60 TeV are presented.

Results from the Telescope Array Experiment

NASA Astrophysics Data System (ADS)

Jui, Charles C. H.; Telescope Array Collaboration

2016-04-01

The Telescope Array (TA) is the largest ultrahigh energy cosmic ray detector in the northern hemisphere. The experiment consists of three fluorescence stations viewing the air space over a surface array of 507 scintillation counters deployed over 700 square kilometers. TA has been in operation since 2008. The most recent results from TA, including that of composition studies and search for arrival direction anisotropy, will be presented. We will also report on the progress of the new TA low energy extension (TALE).

Phase I - Final report: Improved position sensitive detectors for thermal neutrons. Design, fabrication, and results of testing the Phase I - Proof-of-Principal Improved Position Sensitive Thermal Neutron Detector Prototype in the laboratory and at the Intense Pulsed Neutron Source (IPNS), Argonne National Laboratory

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

Hull, Carter D.

A position sensitive neutron detector was designed and fabricated with bundles of individual detector elements with diameters of 120 mm. These neutron scintillating fibers were coupled with optoelectronic arrays to produce a ''Fiber Detector.'' A fiber position sensitive detector was completed and tested with scattered and thermal neutrons. Deployment of improved 2D PSDs with high signal to noise ratios at lower costs per area was the overall objective of the project.

Calibrating the MicroBooNE Photomultiplier Tube (PMT) Array with Michel Electrons from Cosmic Ray Muons

NASA Astrophysics Data System (ADS)

Greene, Amy

2013-04-01

MicroBooNE is a neutrino experiment at Fermilab designed to investigate the 3σ low-energy electron candidate events measured by the MiniBooNE experiment. Neutrinos from the Booster Neutrino Beam are detected by a 89-ton liquid argon time projection chamber, which is expected to start taking data in 2014. MicroBooNE measures both the ionization electrons and scintillation light produced by neutrino interactions in the liquid argon. The scintillation light is collected by an array of 30 PMTs located at one side of the detector. This array can be calibrated using Michel electrons from stopping cosmic ray muons, by fitting the measured PMT response with the theoretical expectation. I will report on the progress of the PMT calibration software that has been developed using the MicroBooNE Monte Carlo.

Terrestrial Gamma Flashes at Ground Level - TETRA-II Instrumentation

NASA Astrophysics Data System (ADS)

Pleshinger, D. J.; Adams, C.; Al-Nussirat, S.; Bai, S.; Banadaki, Y.; Bitzer, P. M.; Cherry, M. L.; Hoffmann, J.; Khosravi, E.; Legault, M.; Orang, M.; Rodriguez, R.; Smith, D.; Trepanier, J. C.; Sunda-Meya, A.; Zimmer, N.

2017-12-01

The TGF and Energetic Thunderstorm Rooftop Array (TETRA-II) consists of an array of BGO scintillators to detect bursts of gamma rays from thunderstorms. TETRA-II will have approximately an order of magnitude greater sensitivity for individual flashes than TETRA-I, an original array of NaI scintillators at Louisiana State University that detected 37 millisecond-scale bursts of gamma rays from 2010-2015. The BGO scintillators increase the energy range of particles detected to 10 MeV and are placed in 20 detectors boxes, each with 1180 cm3 of BGO, at 4 separate locations: the campus of Louisiana State University in Baton Rouge, Louisiana; the campus of the University of Puerto Rico at Utuado, Puerto Rico; the Centro Nacional de Metrologia de Panama (CENAMEP) in Panama City, Panama; and the Severe Weather Institute and Radar & Lightning Laboratories in Huntsville, Alabama. The data are read out with 12 microsecond resolution by National Instruments PCIe 6351 high speed data acquisition cards, with timestamps determined from a 20 MHz clock and a GPS board recording a pulse per second. Details of the array and its instrumentation, along with an overview of initial results, will be presented.

Segmented scintillation antineutrino detector

DOEpatents

Reyna, David

2017-05-09

The various technologies presented herein relate to incorporating a wavelength-shifting material in a scintillator to facilitate absorption of a first electromagnetic particle (e.g., a first photon) having a first wavelength and subsequent generation and emission of a second electromagnetic particle (e.g., a second photon) having a second wavelength. The second electromagnetic particle can be emitted isotropically, with a high probability that the direction of emission of the second electromagnetic particle is disparate to the direction of travel of the first electromagnetic particle (and according angle of incidence). Isotropic emission of the second electromagnetic particle enables the second electromagnetic particle to be retained in the scintillator owing to internal reflection. Accordingly, longer length scintillators can be constructed, and accordingly, the scintillator array has a greater area (and volume) over which to detect electromagnetic particles (e.g., antineutrinos) being emitted from a nuclear reaction.

A piecewise-focused high DQE detector for MV imaging.

PubMed

Star-Lack, Josh; Shedlock, Daniel; Swahn, Dennis; Humber, Dave; Wang, Adam; Hirsh, Hayley; Zentai, George; Sawkey, Daren; Kruger, Isaac; Sun, Mingshan; Abel, Eric; Virshup, Gary; Shin, Mihye; Fahrig, Rebecca

2015-09-01

Electronic portal imagers (EPIDs) with high detective quantum efficiencies (DQEs) are sought to facilitate the use of the megavoltage (MV) radiotherapy treatment beam for image guidance. Potential advantages include high quality (treatment) beam's eye view imaging, and improved cone-beam computed tomography (CBCT) generating images with more accurate electron density maps with immunity to metal artifacts. One approach to increasing detector sensitivity is to couple a thick pixelated scintillator array to an active matrix flat panel imager (AMFPI) incorporating amorphous silicon thin film electronics. Cadmium tungstate (CWO) has many desirable scintillation properties including good light output, a high index of refraction, high optical transparency, and reasonable cost. However, due to the 0 1 0 cleave plane inherent in its crystalline structure, the difficulty of cutting and polishing CWO has, in part, limited its study relative to other scintillators such as cesium iodide and bismuth germanate (BGO). The goal of this work was to build and test a focused large-area pixelated "strip" CWO detector. A 361 × 52 mm scintillator assembly that contained a total of 28 072 pixels was constructed. The assembly comprised seven subarrays, each 15 mm thick. Six of the subarrays were fabricated from CWO with a pixel pitch of 0.784 mm, while one array was constructed from BGO for comparison. Focusing was achieved by coupling the arrays to the Varian AS1000 AMFPI through a piecewise linear arc-shaped fiber optic plate. Simulation and experimental studies of modulation transfer function (MTF) and DQE were undertaken using a 6 MV beam, and comparisons were made between the performance of the pixelated strip assembly and the most common EPID configuration comprising a 1 mm-thick copper build-up plate attached to a 133 mg/cm(2) gadolinium oxysulfide scintillator screen (Cu-GOS). Projection radiographs and CBCT images of phantoms were acquired. The work also introduces the use of a lightweight edge phantom to generate MTF measurements at MV energies and shows its functional equivalence to the more cumbersome slit-based method. Measured and simulated DQE(0)'s of the pixelated CWO detector were 22% and 26%, respectively. The average measured and simulated ratios of CWO DQE(f) to Cu-GOS DQE(f) across the frequency range of 0.0-0.62 mm(-1) were 23 and 29, respectively. 2D and 3D imaging studies confirmed the large dose efficiency improvement and that focus was maintained across the field of view. In the CWO CBCT images, the measured spatial resolution was 7 lp/cm. The contrast-to-noise ratio was dramatically improved reflecting a 22 × sensitivity increase relative to Cu-GOS. The CWO scintillator material showed significantly higher stability and light yield than the BGO material. An efficient piecewise-focused pixelated strip scintillator for MV imaging is described that offers more than a 20-fold dose efficiency improvement over Cu-GOS.

A piecewise-focused high DQE detector for MV imaging

PubMed Central

Star-Lack, Josh; Shedlock, Daniel; Swahn, Dennis; Humber, Dave; Wang, Adam; Hirsh, Hayley; Zentai, George; Sawkey, Daren; Kruger, Isaac; Sun, Mingshan; Abel, Eric; Virshup, Gary; Shin, Mihye; Fahrig, Rebecca

2015-01-01

Purpose: Electronic portal imagers (EPIDs) with high detective quantum efficiencies (DQEs) are sought to facilitate the use of the megavoltage (MV) radiotherapy treatment beam for image guidance. Potential advantages include high quality (treatment) beam’s eye view imaging, and improved cone-beam computed tomography (CBCT) generating images with more accurate electron density maps with immunity to metal artifacts. One approach to increasing detector sensitivity is to couple a thick pixelated scintillator array to an active matrix flat panel imager (AMFPI) incorporating amorphous silicon thin film electronics. Cadmium tungstate (CWO) has many desirable scintillation properties including good light output, a high index of refraction, high optical transparency, and reasonable cost. However, due to the 0 1 0 cleave plane inherent in its crystalline structure, the difficulty of cutting and polishing CWO has, in part, limited its study relative to other scintillators such as cesium iodide and bismuth germanate (BGO). The goal of this work was to build and test a focused large-area pixelated “strip” CWO detector. Methods: A 361  ×  52 mm scintillator assembly that contained a total of 28 072 pixels was constructed. The assembly comprised seven subarrays, each 15 mm thick. Six of the subarrays were fabricated from CWO with a pixel pitch of 0.784 mm, while one array was constructed from BGO for comparison. Focusing was achieved by coupling the arrays to the Varian AS1000 AMFPI through a piecewise linear arc-shaped fiber optic plate. Simulation and experimental studies of modulation transfer function (MTF) and DQE were undertaken using a 6 MV beam, and comparisons were made between the performance of the pixelated strip assembly and the most common EPID configuration comprising a 1 mm-thick copper build-up plate attached to a 133 mg/cm2 gadolinium oxysulfide scintillator screen (Cu-GOS). Projection radiographs and CBCT images of phantoms were acquired. The work also introduces the use of a lightweight edge phantom to generate MTF measurements at MV energies and shows its functional equivalence to the more cumbersome slit-based method. Results: Measured and simulated DQE(0)’s of the pixelated CWO detector were 22% and 26%, respectively. The average measured and simulated ratios of CWO DQE(f) to Cu-GOS DQE(f) across the frequency range of 0.0–0.62 mm−1 were 23 and 29, respectively. 2D and 3D imaging studies confirmed the large dose efficiency improvement and that focus was maintained across the field of view. In the CWO CBCT images, the measured spatial resolution was 7 lp/cm. The contrast-to-noise ratio was dramatically improved reflecting a 22 × sensitivity increase relative to Cu-GOS. The CWO scintillator material showed significantly higher stability and light yield than the BGO material. Conclusions: An efficient piecewise-focused pixelated strip scintillator for MV imaging is described that offers more than a 20-fold dose efficiency improvement over Cu-GOS. PMID:26328960

SPECT detectors: the Anger Camera and beyond

PubMed Central

Peterson, Todd E.; Furenlid, Lars R.

2011-01-01

The development of radiation detectors capable of delivering spatial information about gamma-ray interactions was one of the key enabling technologies for nuclear medicine imaging and, eventually, single-photon emission computed tomography (SPECT). The continuous NaI(Tl) scintillator crystal coupled to an array of photomultiplier tubes, almost universally referred to as the Anger Camera after its inventor, has long been the dominant SPECT detector system. Nevertheless, many alternative materials and configurations have been investigated over the years. Technological advances as well as the emerging importance of specialized applications, such as cardiac and preclinical imaging, have spurred innovation such that alternatives to the Anger Camera are now part of commercial imaging systems. Increased computing power has made it practical to apply advanced signal processing and estimation schemes to make better use of the information contained in the detector signals. In this review we discuss the key performance properties of SPECT detectors and survey developments in both scintillator and semiconductor detectors and their readouts with an eye toward some of the practical issues at least in part responsible for the continuing prevalence of the Anger Camera in the clinic. PMID:21828904

Improving photoelectron counting and particle identification in scintillation detectors with Bayesian techniques

NASA Astrophysics Data System (ADS)

Akashi-Ronquest, M.; Amaudruz, P.-A.; Batygov, M.; Beltran, B.; Bodmer, M.; Boulay, M. G.; Broerman, B.; Buck, B.; Butcher, A.; Cai, B.; Caldwell, T.; Chen, M.; Chen, Y.; Cleveland, B.; Coakley, K.; Dering, K.; Duncan, F. A.; Formaggio, J. A.; Gagnon, R.; Gastler, D.; Giuliani, F.; Gold, M.; Golovko, V. V.; Gorel, P.; Graham, K.; Grace, E.; Guerrero, N.; Guiseppe, V.; Hallin, A. L.; Harvey, P.; Hearns, C.; Henning, R.; Hime, A.; Hofgartner, J.; Jaditz, S.; Jillings, C. J.; Kachulis, C.; Kearns, E.; Kelsey, J.; Klein, J. R.; Kuźniak, M.; LaTorre, A.; Lawson, I.; Li, O.; Lidgard, J. J.; Liimatainen, P.; Linden, S.; McFarlane, K.; McKinsey, D. N.; MacMullin, S.; Mastbaum, A.; Mathew, R.; McDonald, A. B.; Mei, D.-M.; Monroe, J.; Muir, A.; Nantais, C.; Nicolics, K.; Nikkel, J. A.; Noble, T.; O'Dwyer, E.; Olsen, K.; Orebi Gann, G. D.; Ouellet, C.; Palladino, K.; Pasuthip, P.; Perumpilly, G.; Pollmann, T.; Rau, P.; Retière, F.; Rielage, K.; Schnee, R.; Seibert, S.; Skensved, P.; Sonley, T.; Vázquez-Jáuregui, E.; Veloce, L.; Walding, J.; Wang, B.; Wang, J.; Ward, M.; Zhang, C.

2015-05-01

Many current and future dark matter and neutrino detectors are designed to measure scintillation light with a large array of photomultiplier tubes (PMTs). The energy resolution and particle identification capabilities of these detectors depend in part on the ability to accurately identify individual photoelectrons in PMT waveforms despite large variability in pulse amplitudes and pulse pileup. We describe a Bayesian technique that can identify the times of individual photoelectrons in a sampled PMT waveform without deconvolution, even when pileup is present. To demonstrate the technique, we apply it to the general problem of particle identification in single-phase liquid argon dark matter detectors. Using the output of the Bayesian photoelectron counting algorithm described in this paper, we construct several test statistics for rejection of backgrounds for dark matter searches in argon. Compared to simpler methods based on either observed charge or peak finding, the photoelectron counting technique improves both energy resolution and particle identification of low energy events in calibration data from the DEAP-1 detector and simulation of the larger MiniCLEAN dark matter detector.

Status of LUMINEU program to search for neutrinoless double beta decay of 100Mo with cryogenic ZnMoO4 scintillating bolometers

NASA Astrophysics Data System (ADS)

Danevich, F. A.; Bergé, L.; Boiko, R. S.; Chapellier, M.; Chernyak, D. M.; Coron, N.; Devoyon, L.; Drillien, A.-A.; Dumoulin, L.; Enss, C.; Fleischmann, A.; Gastaldo, L.; Giuliani, A.; Gray, D.; Gros, M.; Hervé, S.; Humbert, V.; Ivanov, I. M.; Juillard, A.; Kobychev, V. V.; Koskas, F.; Loidl, M.; Magnier, P.; Makarov, E. P.; Mancuso, M.; de Marcillac, P.; Marnieros, S.; Marrache-Kikuchi, C.; Navick, X.-F.; Nones, C.; Olivieri, E.; Paul, B.; Penichot, Y.; Pessina, G.; Plantevin, O.; Poda, D. V.; Redon, T.; Rodrigues, M.; Shlegel, V. N.; Strazzer, O.; Tenconi, M.; Torres, L.; Tretyak, V. I.; Vasiliev, Ya. V.; Velazquez, M.; Viraphong, O.

2015-10-01

The LUMTNEU program aims at performing a pilot experiment on 0ν2β decay of 100Mo using radiopure ZnMoO4 crystals enriched in 100Mo operated as cryogenic scintillating bolometers. Large volume ZnMoO4 crystal scintillators (˜ 0.3 kg) were developed and tested showing high performance in terms of radiopurity, energy resolution and α/β particle discrimination capability. Zinc molybdate crystal scintillators enriched in 100Mo were grown for the first time by the low-thermal-gradient Czochralski technique with a high crystal yield and an acceptable level of enriched molybdenum irrecoverable losses. A background level of ˜ 0.5 counts/(yr keV ton) in the region of interest can be reached in a large detector array thanks to the excellent detectors radiopurity and particle discrimination capability, suppression of randomly coinciding events by pulse-shape analysis, and anticoincidence cut. These results pave the way to future sensitive searches based on the LUMTNEU technology, capable of approachingand exploring the inverted hierarchy region of the neutrino mass pattern.

Active Well Counting Using New PSD Plastic Detectors

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

Hausladen, Paul; Newby, Jason; McElroy, Robert Dennis

This report presents results and analysis from a series of proof-of-concept measurements to assess the suitability of segmented detectors constructed from Eljen EJ-299-34 PSD-plastic scintillator with pulse-shape discrimination capability for the purposes of quantifying uranium via active neutron coincidence counting. Present quantification of bulk uranium materials for international safeguards and domestic materials control and accounting relies on active neutron coincidence counting systems, such as the Active Well Coincidence Counter (AWCC) and the Uranium Neutron Coincidence Collar (UNCL), that use moderated He-3 proportional counters along with necessarily low-intensity 241Am(Li) neutron sources. Scintillation-based fast-neutron detectors are a potentially superior technology to themore » existing AWCC and UNCL designs due to their spectroscopic capability and their inherently short neutron coincidence times that largely eliminate random coincidences and enable interrogation by stronger sources. One of the past impediments to the investigation and adoption of scintillation counters for the purpose of quantifying bulk uranium was the commercial availability of scintillators having the necessary neutron-gamma pulse-shape discrimination properties only as flammable liquids. Recently, Eljen EJ-299-34 PSD-plastic scintillator became commercially available. The present work is the first assessment of an array of PSD-plastic detectors for the purposes of quantifying bulk uranium. The detector panel used in the present work was originally built as the focal plane for a fast-neutron imager, but it was repurposed for the present investigation by construction of a stand to support the inner well of an AWCC immediately in front of the detector panel. The detector panel and data acquisition of this system are particularly well suited for performing active-well fast-neutron counting of LEU and HEU samples because the active detector volume is solid, the 241Am(Li) interrogating neutrons are largely below the detector threshold, and the segmented construction of the detector modules allow for separation of true neutron-neutron coincidences from inter-detector scattering using the kinematics of neutron scattering. The results from a series of measurements of a suite of uranium standards are presented, and compared to measurements of the same standards and source configurations using the AWCC. Using these results, the performance of the segmented detectors reconfigured as a well counter is predicted and outperforms the AWCC.« less

Development of ultrahigh resolution alpha particle imaging detector using 1 mm channel size Si-PM array

NASA Astrophysics Data System (ADS)

Yamamoto, Seiichi; Kawaguchi, Wataru

2018-06-01

For precise distribution measurements of alpha particles, a high-resolution alpha particle imaging detector is required. Although combining a thin scintillator with a silicon photomultiplier (Si-PM) array is a promising method for achieving high resolution, the spatial resolution is limited. Reducing the size of the Si-PM array is a possible approach to improving the spatial resolution of the alpha particle imaging detector. Consequently, we employed a 1 mm channel size Si-PM array combined with a thin ZnS(Ag) sheet to form an alpha particle imaging detector and evaluated the performance. For the developed alpha particle imaging detector, an Si-PM array with 1 mm x 1 mm channel size arranged 8 x 8 was optically coupled to a ZnS(Ag) sheet with a 1-mm-thick light guide between them. The size of the alpha particle imaging detector was 9.5 mm x 9.5 mm. The spatial resolution of the developed alpha particle imaging detector was 0.14 mm FWHM, and the energy resolution was 74% FWHM for 5.5 MeV alpha particles. The uniformity of the imaging detector at the central part of the field of view (FOV) was ±4.7%. The background count rate was 0.06 counts/min. We obtained various high-resolution phantom images for alpha particles with the developed system. We conclude that the developed imaging detector is promising for high-resolution distribution measurements of alpha particles.

SU-F-T-180: Evaluation of a Scintillating Screen Detector for Proton Beam QA and Acceptance Testing

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

Ghebremedhin, A; Taber, M; Koss, P

2016-06-15

Purpose: To test the performance of a commercial scintillating screen detector for acceptance testing and Quality Assurance of a proton pencil beam scanning system. Method: The detector (Lexitek DRD 400) has 40cm × 40cm field, uses a thin scintillator imaged onto a 16-bit scientific CCD with ∼0.5mm resolution. A grid target and LED illuminators are provided for spatial calibration and relative gain correction. The detector mounts to the nozzle with micron precision. Tools are provided for image processing and analysis of single or multiple Gaussian spots. Results: The bias and gain of the detector were studied to measure repeatability andmore » accuracy. Gain measurements were taken with the LED illuminators to measure repeatability and variation of the lens-CCD pair as a function with f-stop. Overall system gain was measured with a passive scattering (broad) beam whose shape is calibrated with EDR film placed in front of the scintillator. To create a large uniform field, overlapping small fields were recorded with the detector translated laterally and stitched together to cover the full field. Due to the long exposures required to obtain multiple spills of the synchrotron and very high detector sensitivity, borated polyethylene shielding was added to reduce direct radiation events hitting the CCD. Measurements with a micro ion chamber were compared to the detector’s spot profile. Software was developed to process arrays of Gaussian spots and to correct for radiation events. Conclusion: The detector background has a fixed bias, a small component linear in time, and is easily corrected. The gain correction method was validated with 2% accuracy. The detector spot profile matches the micro ion chamber data over 4 orders of magnitude. The multiple spot analyses can be easily used with plan data for measuring pencil beam uniformity and for regular QA comparison.« less

Design optimization for a wearable, gamma-ray and neutron sensitive, detector array with directionality estimation

NASA Astrophysics Data System (ADS)

Ayaz-Maierhafer, Birsen; Britt, Carl G.; August, Andrew J.; Qi, Hairong; Seifert, Carolyn E.; Hayward, Jason P.

2017-10-01

In this study, we report on a constrained optimization and tradeoff study of a hybrid, wearable detector array having directional sensing based upon gamma-ray occlusion. One resulting design uses CLYC detectors while the second feasibility design involves the coupling of gamma-ray-sensitive CsI scintillators and a rubber LiCaAlF6 (LiCAF) neutron detector. The detector systems' responses were investigated through simulation as a function of angle in a two-dimensional plane. The expected total counts, peak-to-total ratio, directionality performance, and detection of 40 K for accurate gain stabilization were considered in the optimization. Source directionality estimation was investigated using Bayesian algorithms. Gamma-ray energies of 122 keV, 662 keV, and 1332 keV were considered. The equivalent neutron capture response compared with 3 He was also investigated for both designs.

Automatic detection of recoil-proton tracks and background rejection criteria in liquid scintillator-micro-capillary-array fast neutron spectrometer

NASA Astrophysics Data System (ADS)

Mor, Ilan; Vartsky, David; Dangendorf, Volker; Tittelmeier, Kai.; Weierganz, Mathias; Goldberg, Mark Benjamin; Bar, Doron; Brandis, Michal

2018-06-01

We describe an analysis procedure for automatic unambiguous detection of fast-neutron-induced recoil proton tracks in a micro-capillary array filled with organic liquid scintillator. The detector is viewed by an intensified CCD camera. This imaging neutron detector possesses the capability to perform high position-resolution (few tens of μm), energy-dispersive transmission-imaging using ns-pulsed beams. However, when operated with CW or DC beams, it also features medium-quality spectroscopic capabilities for incident neutrons in the energy range 2-20 MeV. In addition to the recoil proton events which display a continuous extended track structure, the raw images exhibit complex ion-tracks from nuclear interactions of fast-neutrons in the scintillator, capillaries quartz-matrix and CCD. Moreover, as expected, one also observes a multitude of isolated scintillation spots of varying intensity (henceforth denoted "blobs") that originate from several different sources, such as: fragmented proton tracks, gamma-rays, heavy-ion reactions as well as events and noise that occur in the image-intensifier and CCD. In order to identify the continuous-track recoil proton events and distinguish them from all these background events, a rapid, computerized and automatic track-recognition-procedure was developed. Based on an appropriately weighted analysis of track parameters such as: length, width, area and overall light intensity, the method is capable of distinguishing a single continuous-track recoil proton from typically surrounding several thousands of background events that are found in each CCD frame.

Conceptual design of the AGATA 1 π array at GANIL

NASA Astrophysics Data System (ADS)

Clément, E.; Michelagnoli, C.; de France, G.; Li, H. J.; Lemasson, A.; Barthe Dejean, C.; Beuzard, M.; Bougault, P.; Cacitti, J.; Foucher, J.-L.; Fremont, G.; Gangnant, P.; Goupil, J.; Houarner, C.; Jean, M.; Lefevre, A.; Legeard, L.; Legruel, F.; Maugeais, C.; Ménager, L.; Ménard, N.; Munoz, H.; Ozille, M.; Raine, B.; Ropert, J. A.; Saillant, F.; Spitaels, C.; Tripon, M.; Vallerand, Ph.; Voltolini, G.; Korten, W.; Salsac, M.-D.; Theisen, Ch.; Zielińska, M.; Joannem, T.; Karolak, M.; Kebbiri, M.; Lotode, A.; Touzery, R.; Walter, Ch.; Korichi, A.; Ljungvall, J.; Lopez-Martens, A.; Ralet, D.; Dosme, N.; Grave, X.; Karkour, N.; Lafay, X.; Legay, E.; Kojouharov, I.; Domingo-Pardo, C.; Gadea, A.; Pérez-Vidal, R. M.; Civera, J. V.; Birkenbach, B.; Eberth, J.; Hess, H.; Lewandowski, L.; Reiter, P.; Nannini, A.; De Angelis, G.; Jaworski, G.; John, P.; Napoli, D. R.; Valiente-Dobón, J. J.; Barrientos, D.; Bortolato, D.; Benzoni, G.; Bracco, A.; Brambilla, S.; Camera, F.; Crespi, F. C. L.; Leoni, S.; Million, B.; Pullia, A.; Wieland, O.; Bazzacco, D.; Lenzi, S. M.; Lunardi, S.; Menegazzo, R.; Mengoni, D.; Recchia, F.; Bellato, M.; Isocrate, R.; Egea Canet, F. J.; Didierjean, F.; Duchêne, G.; Baumann, R.; Brucker, M.; Dangelser, E.; Filliger, M.; Friedmann, H.; Gaudiot, G.; Grapton, J.-N.; Kocher, H.; Mathieu, C.; Sigward, M.-H.; Thomas, D.; Veeramootoo, S.; Dudouet, J.; Stézowski, O.; Aufranc, C.; Aubert, Y.; Labiche, M.; Simpson, J.; Burrows, I.; Coleman-Smith, P. J.; Grant, A.; Lazarus, I. H.; Morrall, P. S.; Pucknell, V. F. E.; Boston, A.; Judson, D. S.; Lalović, N.; Nyberg, J.; Collado, J.; González, V.; Kuti, I.; Nyakó, B. M.; Maj, A.; Rudigier, M.

2017-05-01

The Advanced GAmma Tracking Array (AGATA) has been installed at the GANIL facility, Caen-France. This set-up exploits the stable and radioactive heavy-ions beams delivered by the cyclotron accelerator complex of GANIL. Additionally, it benefits from a large palette of ancillary detectors and spectrometers to address in-beam γ-ray spectroscopy of exotic nuclei. The set-up has been designed to couple AGATA with a magnetic spectrometer, charged-particle and neutron detectors, scintillators for the detection of high-energy γ rays and other devices such as a plunger to measure nuclear lifetimes. In this paper, the design and the mechanical characteristics of the set-up are described. Based on simulations, expected performances of the AGATA 1 π array are presented.

High-resolution x-ray imaging using a structured scintillator

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

Hormozan, Yashar, E-mail: hormozan@kth.se; Sychugov, Ilya; Linnros, Jan

2016-02-15

Purpose: In this study, the authors introduce a new generation of finely structured scintillators with a very high spatial resolution (a few micrometers) compared to conventional scintillators, yet maintaining a thick absorbing layer for improved detectivity. Methods: Their concept is based on a 2D array of high aspect ratio pores which are fabricated by ICP etching, with spacings (pitches) of a few micrometers, on silicon and oxidation of the pore walls. The pores were subsequently filled by melting of powdered CsI(Tl), as the scintillating agent. In order to couple the secondary emitted photons of the back of the scintillator arraymore » to a CCD device, having a larger pixel size than the pore pitch, an open optical microscope with adjustable magnification was designed and implemented. By imaging a sharp edge, the authors were able to calculate the modulation transfer function (MTF) of this finely structured scintillator. Results: The x-ray images of individually resolved pores suggest that they have been almost uniformly filled, and the MTF measurements show the feasibility of a few microns spatial resolution imaging, as set by the scintillator pore size. Compared to existing techniques utilizing CsI needles as a structured scintillator, their results imply an almost sevenfold improvement in resolution. Finally, high resolution images, taken by their detector, are presented. Conclusions: The presented work successfully shows the functionality of their detector concept for high resolution imaging and further fabrication developments are most likely to result in higher quantum efficiencies.« less

Recent Results of the Telescope Array Experiment

NASA Astrophysics Data System (ADS)

Ivanov, Dmitri

2015-04-01

The Telescope Array (TA) is the largest cosmic ray experiment in the northern hemisphere and covers 10 PeV to 100 EeV range. TA is a hybrid detector that uses air fluorescence detectors combined with a ground array. TA consists of 507 plastic scintillation counters on a 1.2km square grid, overlooked by 3 fluorescence detector stations, and measures cosmic rays above 1 EeV. TA has collected 6.5 years of data. Results from the TA low energy extension (TALE), which sees cosmic rays down to 10 PeV, will also be shown. This contribution will consist of three parts. First, we will present the cosmic ray energy spectrum measured over 4 decades in energy. Next, we will discuss the latest results of the measurements of cosmic ray mass composition by the TA fluorescence detectors. Finally, we will show the latest results of the TA anisotropy measurements at the highest energies, where we have seen a concentration of events, called the ``hotspot,'' centered in the Ursa Major. For the Telescope Array Collaboration. Done...processed 1261 records...10:46:59 Beginning APS data extraction...10:47:48

Gamma-Ray Spectroscopy at TRIUMF-ISAC

NASA Astrophysics Data System (ADS)

Garrett, P. E.; Svensson, C. E.; Ball, G. C.; Hackman, G.; Zganjar, E. F.; Andreoiu, C.; Andreyev, A.; Ashley, S. F.; Austin, R. A. E.; Bandyopadhyay, D.; Becker, J. A.; Chan, S.; Coombes, H.; Churchman, R.; Chakrawarthy, R. S.; Finlay, P.; Grinyer, G. F.; Hyland, B.; Illes, E.; Jones, G. A.; Kulp, W. D.; Leslie, J. R.; Mattoon, C.; Morton, A. C.; Pearson, C. J.; Phillips, A. A.; Regan, P. H.; Ressler, J. J.; Sarazin, F.; Schumaker, M. A.; Schwarzenberg, J.; Smith, M. B.; Valiente-Dobón, J. J.; Walker, P. M.; Williams, S. J.; Waddington, J. C.; Watters, L. M.; Wong, J.; Wood, J. L.

2006-03-01

The 8π spectrometer at TRIUMF-ISAC consists of 20 Compton-suppressed germanium detectors and various auxiliary devices. The Ge array, once used for studies of nuclei at high angular momentum, has been transformed into the world's most powerful device dedicated to radioactive-decay studies. Many improvements in the spectrometer have been made, including a high-throughput data acquisition system, installation of a moving tape collector, incorporation of an array of 20 plastic scintillators for β-particle tagging, 5 Si(Li) detectors for conversion electrons, and 10 BaF2 detectors for fast-lifetime measurements. Experiments can be performed where data from all detectors are collected simultaneously, resulting in a very detailed view of the nucleus through radioactive decay. A number of experimental programmes have been launched that take advantage of the versatility of the spectrometer, and the intense beams available at TRIUMF-ISAC.

A simple procedure for γ- γ lifetime measurements using multi-element fast-timing arrays

NASA Astrophysics Data System (ADS)

Régis, J.-M.; Dannhoff, M.; Jolie, J.

2018-07-01

The lifetimes of nuclear excited states are important observables in nuclear physics. Their precise measurement is of key importance for developing and testing nuclear models as they are directly linked with the quantum nature of the nuclear system. The γ- γ timing technique represents a direct lifetime determination by means of time-difference measurements between the γ rays which directly feed and decay from a nuclear excited state. Using arrays of very-fast scintillator detectors, picosecond-sensitive time-difference measurements can be performed. We propose to construct a symmetric energy-energy-time cube as is usually done to perform γ- γ coincidence analyses and lifetime determination with high-resolution germanium detectors. By construction, a symmetric mean time-walk characteristics is obtained, that can be precisely determined and used as a single time correction for all the data independently of the detectors. We present the results of timing characteristics measurements of an array with six LaBr3(Ce) detectors, as obtained using a 152Eu point γ-ray source. Compared with a single detector pair, the time resolution of the symmetrised time-difference spectra of the array is nearly unaffected.

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.

The SAFIR experiment: Concept, status and perspectives

NASA Astrophysics Data System (ADS)

Becker, Robert; Buck, Alfred; Casella, Chiara; Dissertori, Günther; Fischer, Jannis; Howard, Alexander; Ito, Mikiko; Khateri, Parisa; Lustermann, Werner; Oliver, Josep F.; Röser, Ulf; Warnock, Geoffrey; Weber, Bruno

2017-02-01

The SAFIR development represents a novel Positron Emission Tomography (PET) detector, conceived for preclinical fast acquisitions inside the bore of a Magnetic Resonance Imaging (MRI) scanner. The goal is hybrid and simultaneous PET/MRI dynamic studies at unprecedented temporal resolutions of a few seconds. The detector relies on matrices of scintillating LSO-based crystals coupled one-to-one with SiPM arrays and readout by fast ASICs with excellent timing resolution and high rate capabilities. The paper describes the detector concept and the initial results in terms of simulations and characterisation measurements.

SONTRAC: A solar neutron track chamber detector

NASA Technical Reports Server (NTRS)

Frye, G. M., Jr.; Jenkins, T. L.; Owens, A.

1985-01-01

The recent detection on the solar maximum mission (SMM) satellite of high energy neutrons emitted during large solar flares has provided renewed incentive to design a neutron detector which has the sensitivity, energy resolution, and time resolution to measure the neutron time and energy spectra with sufficient precision to improve our understanding of the basic flare processes. Over the past two decades a variety of neutron detectors has been flown to measure the atmospheric neutron intensity above 10 MeV and to search for solar neutrons. The SONTRAC (Solar Neutron Track Chamber) detector, a new type of neutron detector which utilizes n-p scattering and has a sensitivity 1-3 orders of magnitude greater than previous instruments in the 20-200 MeV range is described. The energy resolution is 1% for neutron kinetic energy, T sub n 50 MeV. When used with a coded aperture mask at 50 m (as would be possible on the space station) an angular resolution of approx. 4 arc sec could be achieved, thereby locating the sites of high energy nuclear interactions with an angular precision comparable to the existing x-ray experiments on SMM. The scintillation chamber is investigated as a track chamber for high energy physics, either by using arrays of scintillating optical fibers or by optical imaging of particle trajectories in a block of scintillator.

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

NASA Astrophysics Data System (ADS)

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

2017-01-01

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

Design, development and evaluation of a resistor-based multiplexing circuit for a 20×20 SiPM array

NASA Astrophysics Data System (ADS)

Wang, Zhonghai; Sun, Xishan; Lou, Kai; Meier, Joseph; Zhou, Rong; Yang, Chaowen; Zhu, Xiaorong; Shao, Yiping

2016-04-01

One technical challenge in developing a large-size scintillator detector with multiple Silicon Photomultiplier (SiPM) arrays is to read out a large number of detector output channels. To achieve this, different signal multiplexing circuits have been studied and applied with different performances and cost-effective tradeoffs. Resistor-based multiplexing circuits exhibit simplicity and signal integrity, but also present the disadvantage of timing shift among different channels. In this study, a resistor-based multiplexing circuit for a large-sized SiPM array readout was developed and evaluated by simulation and experimental studies. Similarly to a multiplexing circuit used for multi-anode PMT, grounding and branching resistors were connected to each SiPM output channel. The grounding resistor was used to simultaneously reduce the signal crosstalk among different channels and to improve timing performance. Both grounding and branching resistor values were optimized to maintain a balanced performance of the event energy, timing, and positioning. A multiplexing circuit was implemented on a compact PCB and applied for a flat-panel detector which consisted of a 32×32 LYSO scintillator crystals optically coupled to 5×5 SiPM arrays for a total 20×20 output channels. Test results showed excellent crystal identification for all 1024 LYSO crystals (each with 2×2×30 mm3 size) with 22Na flood-source irradiation. The measured peak-to-valley ratio from typical crystal map profile is around 3:1 to 6.6:1, an average single crystal energy resolution of about 17.3%, and an average single crystal timing resolution of about 2 ns. Timing shift among different crystals, as reported in some other resistor-based multiplexing circuit designs, was not observed. In summary, we have designed and implemented a practical resistor-based multiplexing circuit that can be readily applied for reading out a large SiPM array with good detector performance.

Recent results from the Telescope Array Experiment

NASA Astrophysics Data System (ADS)

Abbasi, Rasha; Telescope Array Collaboration

2016-03-01

The Telescope Array (TA) is the largest ultrahigh energy cosmic rays detector in the northern hemisphere. TA is a hybrid detector comprised of three air fluorescence stations and a large surface array consisting of 507 scintillator counters. Each of the three fluorescence stations, located at the periphery of the ground array, views 108 degrees in azimuth and up to 30 degrees in elevation. The surface detectors are arranged in a square grid of 1.2 km spacing, covering over 700 square kilometers. TA has collected more than seven years of data. In this talk, we will present some of the main results on the cosmic rays composition and energy spectrum obtained by TA and its low energy extension (TALE). Finally, we will present our results from the search for arrival direction anisotropy, including the observed large excess of events at the highest energies, seen in the region of the northern sky centered on Ursa Major. Based on the current results, the ``hot spot'' in particular, TA is pursuing the expansion of the surface array to four times its current size.

Fiber optic thermal/fast neutron and gamma ray scintillation detector

DOEpatents

Neal, John S.; Mihalczo, John T.

2006-11-28

A detector system that combines a .sup.6Li loaded glass fiber scintillation thermal neutron detector with a fast scintillation detector in a single layered structure. Detection of thermal and fast neutrons and ionizing electromagnetic radiation is achieved in the unified detector structure. The fast scintillator replaces the polyethelene moderator layer adjacent the .sup.6Li loaded glass fiber panel of the neutron detector and acts as the moderator for the glass fibers. Fast neutrons, x-rays and gamma rays are detected in the fast scintillator. Thermal neutrons, x-rays and gamma rays are detected in the glass fiber scintillator.

Focal-plane detector system for the KATRIN experiment

NASA Astrophysics Data System (ADS)

Amsbaugh, J. F.; Barrett, J.; Beglarian, A.; Bergmann, T.; Bichsel, H.; Bodine, L. I.; Bonn, J.; Boyd, N. M.; Burritt, T. H.; Chaoui, Z.; Chilingaryan, S.; Corona, T. J.; Doe, P. J.; Dunmore, J. A.; Enomoto, S.; Formaggio, J. A.; Fränkle, F. M.; Furse, D.; Gemmeke, H.; Glück, F.; Harms, F.; Harper, G. C.; Hartmann, J.; Howe, M. A.; Kaboth, A.; Kelsey, J.; Knauer, M.; Kopmann, A.; Leber, M. L.; Martin, E. L.; Middleman, K. J.; Myers, A. W.; Oblath, N. S.; Parno, D. S.; Peterson, D. A.; Petzold, L.; Phillips, D. G.; Renschler, P.; Robertson, R. G. H.; Schwarz, J.; Steidl, M.; Tcherniakhovski, D.; Thümmler, T.; Van Wechel, T. D.; VanDevender, B. A.; Vöcking, S.; Wall, B. L.; Wierman, K. L.; Wilkerson, J. F.; Wüstling, S.

2015-04-01

The focal-plane detector system for the KArlsruhe TRItium Neutrino (KATRIN) experiment consists of a multi-pixel silicon p-i-n-diode array, custom readout electronics, two superconducting solenoid magnets, an ultra high-vacuum system, a high-vacuum system, calibration and monitoring devices, a scintillating veto, and a custom data-acquisition system. It is designed to detect the low-energy electrons selected by the KATRIN main spectrometer. We describe the system and summarize its performance after its final installation.

Scintillation Detector for the Measurement of Ultra-Heavy Cosmic Rays on the Super-TIGER Experiment

NASA Technical Reports Server (NTRS)

Link, Jason

2011-01-01

We discuss the design and construction of the scintillation detectors for the Super-TIGER experiment. Super-TIGER is a large-area (5.4sq m) balloon-borne experiment designed to measure the abundances of cosmic-ray nuclei between Z= 10 and Z=56. It is based on the successful TIGER experiment that flew in Antarctica in 2001 and 2003. Super-TIGER has three layers of scintillation detectors, two Cherenkov detectors and a scintillating fiber hodoscope. The scintillation detector employs four wavelength shifter bars surrounding the edges of the scintillator to collect the light from particles traversing the detector. PMTs are optically coupled at both ends of the bars for light collection. We report on laboratory performance of the scintillation counters using muons. In addition we discuss the design challenges and detector response over this broad charge range including the effect of scintilator saturation.

Comparison of experimental results of a Quad-CZT array detector, a NaI(Tl), a LaBr3(Ce), and a HPGe for safeguards applications

NASA Astrophysics Data System (ADS)

Kwak, S.-W.; Choi, J.; Park, S. S.; Ahn, S. H.; Park, J. S.; Chung, H.

2017-11-01

A compound semiconductor detector, CdTe (or CdZnTe), has been used in various areas including nuclear safeguards applications. To address its critical drawback, low detection efficiency, which leads to a long measurement time, a Quad-CZT array-based gamma-ray spectrometer in our previous study has been developed by combining four individual CZT detectors. We have re-designed the developed Quad-CZT array system to make it more simple and compact for a hand-held gamma-ray detector. The objective of this paper aims to compare the improved Quad-CZT array system with the traditional gamma-ray spectrometers (NaI(Tl), LaBr3(Ce), HPGe); these detectors currently have been the most commonly used for verification of nuclear materials. Nuclear materials in different physical forms in a nuclear facility of Korea were measured by the Quad-CZT array system and the existing gamma-ray detectors. For measurements of UO2 pellets and powders, and fresh fuel rods, the Quad-CZT array system turned out to be superior to the NaI(Tl) and LaBr3(Ce). For measurements of UF6 cylinders with a thick wall, the Quad-CZT array system and HPGe gave similar accuracy under the same measurement time. From the results of the field tests conducted, we can conclude that the improved Quad-CZT array system would be used as an alternative to HPGes and scintillation detectors for the purpose of increasing effectivenss and efficiency of safeguards applications. This is the first paper employing a multi-element CZT array detector for measurement of nuclear materials—particularly uranium in a UF6 cylinder—in a real nuclear facility. The present work also suggests that the multi-CZT array system described in this study would be one promising method to address a serious weakness of CZT-based radiation detection.

A DOI Detector With Crystal Scatter Identification Capability for High Sensitivity and High Spatial Resolution PET Imaging.

PubMed

Gu, Z; Prout, D L; Silverman, R W; Herman, H; Dooraghi, A; Chatziioannou, A F

2015-06-01

A new phoswich detector is being developed at the Crump Institute, aiming to provide improvements in sensitivity, and spatial resolution for PET. The detector configuration is comprised of two layers of pixelated scintillator crystal arrays, a glass light guide and a light detector. The annihilation photon entrance (top) layer is a 48 × 48 array of 1.01 × 1.01 × 7 mm 3 LYSO crystals. The bottom layer is a 32 × 32 array of 1.55 × 1.55 × 9 mm 3 BGO crystals. A tapered, multiple-element glass lightguide is used to couple the exit end of the BGO crystal array (52 × 52 mm 2 ) to the photosensitive area of the Position Sensitive Photomultiplier Tube (46 × 46 mm 2 ), allowing the creation of flat panel detectors without gaps between the detector modules. Both simulations and measurements were performed to evaluate the characteristics and benefits of the proposed design. The GATE Monte Carlo simulation indicated that the total fraction of the cross layer crystal scatter (CLCS) events in singles detection mode for this detector geometry is 13.2%. The large majority of these CLCS events (10.1% out of 13.2%) deposit most of their energy in a scintillator layer other than the layer of first interaction. Identification of those CLCS events for rejection or correction may lead to improvements in data quality and imaging performance. Physical measurements with the prototype detector showed that the LYSO, BGO and CLCS events were successfully identified using the delayed charge integration (DCI) technique, with more than 95% of the LYSO and BGO crystal elements clearly resolved. The measured peak-to-valley ratios (PVR) in the flood histograms were 3.5 for LYSO and 2.0 for BGO. For LYSO, the energy resolution ranged from 9.7% to 37.0% full width at half maximum (FWHM), with a mean of 13.4 ± 4.8%. For BGO the energy resolution ranged from 16.0% to 33.9% FWHM, with a mean of 18.6 ± 3.2%. In conclusion, these results demonstrate that the proposed detector is feasible and can potentially lead to a high spatial resolution, high sensitivity and DOI PET system.

A DOI Detector With Crystal Scatter Identification Capability for High Sensitivity and High Spatial Resolution PET Imaging

PubMed Central

Gu, Z.; Prout, D. L.; Silverman, R. W.; Herman, H.; Dooraghi, A.; Chatziioannou, A. F.

2015-01-01

A new phoswich detector is being developed at the Crump Institute, aiming to provide improvements in sensitivity, and spatial resolution for PET. The detector configuration is comprised of two layers of pixelated scintillator crystal arrays, a glass light guide and a light detector. The annihilation photon entrance (top) layer is a 48 × 48 array of 1.01 × 1.01 × 7 mm3 LYSO crystals. The bottom layer is a 32 × 32 array of 1.55 × 1.55 × 9 mm3 BGO crystals. A tapered, multiple-element glass lightguide is used to couple the exit end of the BGO crystal array (52 × 52 mm2) to the photosensitive area of the Position Sensitive Photomultiplier Tube (46 × 46 mm2), allowing the creation of flat panel detectors without gaps between the detector modules. Both simulations and measurements were performed to evaluate the characteristics and benefits of the proposed design. The GATE Monte Carlo simulation indicated that the total fraction of the cross layer crystal scatter (CLCS) events in singles detection mode for this detector geometry is 13.2%. The large majority of these CLCS events (10.1% out of 13.2%) deposit most of their energy in a scintillator layer other than the layer of first interaction. Identification of those CLCS events for rejection or correction may lead to improvements in data quality and imaging performance. Physical measurements with the prototype detector showed that the LYSO, BGO and CLCS events were successfully identified using the delayed charge integration (DCI) technique, with more than 95% of the LYSO and BGO crystal elements clearly resolved. The measured peak-to-valley ratios (PVR) in the flood histograms were 3.5 for LYSO and 2.0 for BGO. For LYSO, the energy resolution ranged from 9.7% to 37.0% full width at half maximum (FWHM), with a mean of 13.4 ± 4.8%. For BGO the energy resolution ranged from 16.0% to 33.9% FWHM, with a mean of 18.6 ± 3.2%. In conclusion, these results demonstrate that the proposed detector is feasible and can potentially lead to a high spatial resolution, high sensitivity and DOI PET system. PMID:26478600

A DOI Detector With Crystal Scatter Identification Capability for High Sensitivity and High Spatial Resolution PET Imaging

NASA Astrophysics Data System (ADS)

Gu, Z.; Prout, D. L.; Silverman, R. W.; Herman, H.; Dooraghi, A.; Chatziioannou, A. F.

2015-06-01

A new phoswich detector is being developed at the Crump Institute, aiming to provide improvements in sensitivity, and spatial resolution for PET. The detector configuration is comprised of two layers of pixelated scintillator crystal arrays, a glass lightguide and a light detector. The annihilation photon entrance (top) layer is a 48×48 array of 1.01 × 1.01 × 7 mm3 LYSO crystals. The bottom layer is a 32 × 32 array of 1.55 × 1.55 × 9 mm3 BGO crystals. A tapered, multiple-element glass lightguide is used to couple the exit end of the BGO crystal array (52 × 52 mm2) to the photosensitive area of the Position Sensitive Photomultiplier Tube (46 × 46 mm2), allowing the creation of flat panel detectors without gaps between the detector modules. Both simulations and measurements were performed to evaluate the characteristics and benefits of the proposed design. The GATE Monte Carlo simulation indicated that the total fraction of the cross layer crystal scatter (CLCS) events in singles detection mode for this detector geometry is 13.2%. The large majority of these CLCS events (10.1% out of 13.2%) deposit most of their energy in a scintillator layer other than the layer of first interaction. Identification of those CLCS events for rejection or correction may lead to improvements in data quality and imaging performance. Physical measurements with the prototype detector showed that the LYSO, BGO and CLCS events were successfully identified using the delayed charge integration (DCI) technique, with more than 95% of the LYSO and BGO crystal elements clearly resolved. The measured peak-to-valley ratios (PVR) in the flood histograms were 3.5 for LYSO and 2.0 for BGO. For LYSO, the energy resolution ranged from 9.7% to 37.0% full width at half maximum (FWHM), with a mean of 13.4 ± 4.8%. For BGO the energy resolution ranged from 16.0% to 33.9% FWHM, with a mean of 18.6 ± 3.2%. In conclusion, these results demonstrate that the proposed detector is feasible and can potentially lead to a high spatial resolution, high sensitivity and DOI PET system.

High-precision branching-ratio measurement for the superallowed β+ emitter 74Rb

NASA Astrophysics Data System (ADS)

Dunlop, R.; Ball, G. C.; Leslie, J. R.; Svensson, C. E.; Towner, I. S.; Andreoiu, C.; Chagnon-Lessard, S.; Chester, A.; Cross, D. S.; Finlay, P.; Garnsworthy, A. B.; Garrett, P. E.; Glister, J.; Hackman, G.; Hadinia, B.; Leach, K. G.; Rand, E. T.; Starosta, K.; Tardiff, E. R.; Triambak, S.; Williams, S. J.; Wong, J.; Yates, S. W.; Zganjar, E. F.

2013-10-01

A high-precision branching-ratio measurement for the superallowed β+ decay of 74Rb was performed at the TRIUMF Isotope Separator and Accelerator (ISAC) radioactive ion-beam facility. The scintillating electron-positron tagging array (SCEPTAR), composed of 10 thin plastic scintillators, was used to detect the emitted β particles; the 8π spectrometer, an array of 20 Compton-suppressed HPGe detectors, was used for detecting γ rays that were emitted following Gamow-Teller and nonanalog Fermi β+ decays of 74Rb; and the Pentagonal Array of Conversion Electron Spectrometers (PACES), an array of 5 Si(Li) detectors, was employed for measuring β-delayed conversion electrons. Twenty-three excited states were identified in 74Kr following 8.241(4)×108 detected 74Rb β decays. A total of 58 γ-ray and electron transitions were placed in the decay scheme, allowing the superallowed branching ratio to be determined as B0=99.545(31)%. Combined with previous half-life and Q-value measurements, the superallowed branching ratio measured in this work leads to a superallowed ft value of 3082.8(65) s. Comparisons between this superallowed ft value and the world-average-corrected Ft¯ value, as well as the nonanalog Fermi branching ratios determined in this work, provide guidance for theoretical models of the isospin-symmetry-breaking corrections in this mass region.

Comparison of SensL and Hamamatsu 4×4 channel SiPM arrays in gamma spectrometry with scintillators

NASA Astrophysics Data System (ADS)

Grodzicka-Kobylka, M.; Szczesniak, T.; Moszyński, M.

2017-06-01

The market of Silicon Photomultipliers (SiPMs) consists of many manufacturers that produce their detectors in different technology. Hamamatsu (Japan) and SensL (Ireland) seems to be the most popular companies that produce large SiPM arrays. The aim of this work is characterization and comparison of 4×4 channel SiPM arrays produced by these two producers. Both of the tested SiPMs are made in through-silicon via (TSV) technology, consist of 16, 3×3 mm avalanche photodiode (APD) cells and have fill factor slightly above 60%. The largest difference is a single APD cell size and hence total number of APD cells (55,424 for Hamamatsu, 76,640 for SensL). In the case of SensL SiPM, its spectral response characteristics is shifted slightly toward shorter wavelengths with maximum at 420 nm (450 nm for Hamamatsu). The presented measurements cover selection of the SiPM optimum operating voltage (in respect to energy resolution), verification of the excess noise factor and check of the linearity characteristics. Moreover, the gamma spectrometry with LSO, BGO and CsI:Tl scintillators together with pulse characteristics for these crystals (rise time and fall time) is reported, as well as temperature dependence. The presented measurements show better performance of the SensL array comparing to the Hamamatsu detector.

EAS thermal neutron detection with the PRISMA-LHAASO-16 experiment

NASA Astrophysics Data System (ADS)

Li, B.-B.; Alekseenko, V. V.; Cui, S.-w.; Chen, T.-L.; Dangzengluobu; Feng, S.-H.; Gao, Q.; Liu, Y.; Huang, Q.-C.; He, Y.-Y.; Liu, M.-Y.; Ma, X.-H.; Pozdnyakov, E. I.; Shchegolev, O. B.; Shen, F.-Z.; Stenkin, Yu. V.; Stepanov, V. I.; Yanin, Ya. V.; Yao, J.-D.; Zhou, R.

2017-12-01

EAS (extensive air shower) thermal neutron measurement gives advantages to study energy and mass composition of primary cosmic rays especially in the knee region. After the success of the PRISMA-YBJ experiment, we build a new EAS thermal neutron detection array at Tibet University, Lhasa, China (3700 m a.s.l.) in March, 2017. This prototype array so called "PRISMA-LHAASO-16" consists of 16 EAS EN-detectors ("EN" is abbreviation for electron and neutron) measuring two main EAS components: hadronic and electromagnetic ones. Different from PRISMA-YBJ, these detectors use a thin layer of a novel type of ZnS(Ag) scintillator alloyed with natural boron compound for thermal neutron capture. PRISMA-LHAASO-16 will be moved to the LHAASO site in the near future. In this paper, we introduce principle of the detection technique, deployment of the array, and the test results of the array.

Development of the new trigger for VANDLE neutron detector

NASA Astrophysics Data System (ADS)

Hasse, Adam; Taylor, Steven; Daugherty, Hadyn; Grzywacz, Robert

2014-09-01

Beta-delayed neutron emission (βn) is the dominant decay channel for the majority of very neutron-rich nuclei. In order to study these decays a new detector system called the Versatile Array of Neutron Detectors at Low Energy (VANDLE) was constructed. A critical part of this neutron time of flight detector is a trigger unit. This trigger is sensitive to electron from beta decay down to very low energies, insensitive to gamma rays and have a good timing performance, better than 1 ns. In order to satisfy these condition, we have developed a new system, which utilizes plastic scintillator but uses recently developed light readout technique, based on the so called Silicon Photomultiplier, manufactured by Sensl. New system has been developed and performance tested using digital data acquisition system at the University of Tennessee and will be utilized in future experiments involving VANDLE. Beta-delayed neutron emission (βn) is the dominant decay channel for the majority of very neutron-rich nuclei. In order to study these decays a new detector system called the Versatile Array of Neutron Detectors at Low Energy (VANDLE) was constructed. A critical part of this neutron time of flight detector is a trigger unit. This trigger is sensitive to electron from beta decay down to very low energies, insensitive to gamma rays and have a good timing performance, better than 1 ns. In order to satisfy these condition, we have developed a new system, which utilizes plastic scintillator but uses recently developed light readout technique, based on the so called Silicon Photomultiplier, manufactured by Sensl. New system has been developed and performance tested using digital data acquisition system at the University of Tennessee and will be utilized in future experiments involving VANDLE. Department of Physics and Astronomy, University of Tennessee, Knoxville, USA.

A new water-equivalent 2D plastic scintillation detectors array for the dosimetry of megavoltage energy photon beams in radiation therapy.

PubMed

Guillot, Mathieu; Beaulieu, Luc; Archambault, Louis; Beddar, Sam; Gingras, Luc

2011-12-01

The objective of this work is to present a new 2D plastic scintillation detectors array (2D-PSDA) designed for the dosimetry of megavoltage (MV) energy photon beams in radiation therapy and to characterize its basic performance. We developed a 2D detector array consisting of 781 plastic scintillation detectors (PSDs) inserted into a plane of a water-equivalent phantom. The PSDs were distributed on a 26 × 26 cm(2) grid, with an interdetector spacing of 10 mm, except for two perpendicular lines centered on the detection plane, where the spacing was 5 mm. Each PSD was made of a 1 mm diameter by 3 mm long cylindrical polystyrene scintillating fiber coupled to a clear nonscintillating plastic optical fiber. All of the light signals emitted by the PSDs were read simultaneously with an optical system at a rate of one measurement per second. We characterized the performance of the optical system, the angular dependency of the device, and the perturbation of dose distributions caused by the hundreds of PSDs inserted into the phantom. We also evaluated the capacity of the system to monitor complex multileaf collimator (MLC) sequences such as those encountered in step-and-shoot intensity modulated radiation therapy (IMRT) plans. We compared our results with calculations performed by a treatment planning system and with measurements taken with a 2D ionization chamber array and with a radiochromic film. The detector array that we developed allowed us to measure doses with an average precision of better than 1% for cumulated doses equal to or greater than 6.3 cGy. Our results showed that the dose distributions produced by the 6-MV photon beam are not perturbed (within ±1.1%) by the presence of the hundreds of PSDs located into the phantom. The results also showed that the variations in the beam incidences have little effect on the dose response of the device. For all incidences tested, the passing rates of the gamma tests between the 2D-PSDA and the treatment planning system were higher than 97.5% when the standard clinical tolerances of 3% or 3 mm were used. Excellent agreement was obtained between the doses measured and calculated when we used the 2D-PSDA for monitoring a MLC sequence from a step-and-shoot IMRT plan. We demonstrated the feasibility of using a large number of PSDs in a new 2D-PSDA for the dosimetry of MV energy photon beams in radiation therapy. The excellent precision, accuracy, and low angular dependence of the device indicate that such a prototype could potentially be used as a high-accuracy quality assurance tool for IMRT and arc therapy patient plan verification. The homogeneity and water-equivalence of the prototype we built suggest that this technology could be extended to multiple detection planes by arranging the fibers into more complex orientations, opening the possibility for 3D dosimetry with PSDs.

Gamma decay of pygmy states in 90,94Zr from inelastic scattering of light ions

NASA Astrophysics Data System (ADS)

Crespi, F. C. L.; Bracco, A.; Tamii, A.; Blasi, N.; Camera, F.; Wieland, O.; Aoi, N.; Balabanski, D.; Bassauer, S.; Brown, A. S.; Carpenter, M. P.; Carroll, J. J.; Ciemala, M.; Czeszumska, A.; Davies, P. J.; Donaldson, L.; Fang, Y.; Fujita, H.; Gey, G.; Hoang, T. H.; Ichige, N.; Ideguchi, E.; Inoue, A.; Isaak, J.; Iwamoto, C.; Jenkins, D. G.; Jin, O. H.; Klaus, T.; Kobayashi, N.; Koike, T.; Krzysiek, M.; Raju, M. Kumar; Liu, M.; Maj, A.; Montanari, D.; Morris, L.; Noji, S.; Pickstone, S. G.; Savran, D.; Spieker, M.; Steinhilber, G.; Sullivan, C.; Wasilewska, B.; Werner, V.; Yamamoto, T.; Yamamoto, Y.; Zhou, X.; Zhu, S.

2018-05-01

We performed experiments to study the low-energy part of the E1 response (Pygmy Dipole Resonance) in 90,94Zr nuclei, by measuring the (p,p’γ) and (α,α’γ) inelastic scattering reactions at energies Ebeam,p = 80 MeV and Ebeam,α = 130 MeV respectively. The inelastically scattered particles were measured by employing the high-resolution spectrometer Grand Raiden. The gamma-rays emitted following the de-excitation of the Zr target nuclei were detected using both the clover type HPGe detectors of the CAGRA array and the large volume LaBr3:Ce scintillation detectors from the HECTOR+ array. Some preliminary results are presented here.

High-energy photon spectra from a coaxial gas-puff experiment

NASA Astrophysics Data System (ADS)

Warren, S. W. R.; Degnan, J. H.; Beason, C. W.; Price, D. W.; Snell, M. P.

1987-04-01

An array of plastic scintillator/photomultiplier detectors was used to determine the high-energy (h x nu greater than 35 keV) photon spectra of a 130-kJ, 60-kV gas-injected coaxial-gun experiment. The detector array used six different filter-material/thickness combinations. High-energy photon signals were readily observed. The spectra were determined by deconvolution. The spectra have three characteristic components: radiative emission from high-Z impurities in the plasma, beam-target excited line emission, and thick-target bremsstrahlung from an electron beam generated in the plasma column. The electron beam consistent with the thick-target bremsstrahlung assumption was of the order of 100 A above 10 keV.

Recent Developments in PET Instrumentation

PubMed Central

Peng, Hao; Levin, Craig S.

2013-01-01

Positron emission tomography (PET) is used in the clinic and in vivo small animal research to study molecular processes associated with diseases such as cancer, heart disease, and neurological disorders, and to guide the discovery and development of new treatments. This paper reviews current challenges of advancing PET technology and some of newly developed PET detectors and systems. The paper focuses on four aspects of PET instrumentation: high photon detection sensitivity; improved spatial resolution; depth-of-interaction (DOI) resolution and time-of-flight (TOF). Improved system geometry, novel non-scintillator based detectors, and tapered scintillation crystal arrays are able to enhance the photon detection sensitivity of a PET system. Several challenges for achieving high resolution with standard scintillator-based PET detectors are discussed. Novel detectors with 3-D positioning capability have great potential to be deployed in PET for achieving spatial resolution better than 1 mm, such as cadmium-zinc-telluride (CZT) and position-sensitive avalanche photodiodes (PSAPDs). DOI capability enables a PET system to mitigate parallax error and achieve uniform spatial resolution across the field-of-view (FOV). Six common DOI designs, as well as advantages and limitations of each design, are discussed. The availability of fast scintillation crystals such as LaBr3, and the silicon photomultiplier (SiPM) greatly advances TOF-PET development. Recent instrumentation and initial results of clinical trials are briefly presented. If successful, these technology advances, together with new probe molecules, will substantially enhance the molecular sensitivity of PET and thus increase its role in preclinical and clinical research as well as evaluating and managing disease in the clinic. PMID:20497121

Trigger design for a gamma ray detector of HIRFL-ETF

NASA Astrophysics Data System (ADS)

Du, Zhong-Wei; Su, Hong; Qian, Yi; Kong, Jie

2013-10-01

The Gamma Ray Array Detector (GRAD) is one subsystem of HIRFL-ETF (the External Target Facility (ETF) of the Heavy Ion Research Facility in Lanzhou (HIRFL)). It is capable of measuring the energy of gamma-rays with 1024 CsI scintillators in in-beam nuclear experiments. The GRAD trigger should select the valid events and reject the data from the scintillators which are not hit by the gamma-ray. The GRAD trigger has been developed based on the Field Programmable Gate Array (FPGAs) and PXI interface. It makes prompt trigger decisions to select valid events by processing the hit signals from the 1024 CsI scintillators. According to the physical requirements, the GRAD trigger module supplies 12-bit trigger information for the global trigger system of ETF and supplies a trigger signal for data acquisition (DAQ) system of GRAD. In addition, the GRAD trigger generates trigger data that are packed and transmitted to the host computer via PXI bus to be saved for off-line analysis. The trigger processing is implemented in the front-end electronics of GRAD and one FPGA of the GRAD trigger module. The logic of PXI transmission and reconfiguration is implemented in another FPGA of the GRAD trigger module. During the gamma-ray experiments, the GRAD trigger performs reliably and efficiently. The function of GRAD trigger is capable of satisfying the physical requirements.

Focal-plane detector system for the KATRIN experiment

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

Amsbaugh, J. F.; Barrett, J.; Beglarian, A.

Here, the local plane detector system for the KArlsiuhe TRItium Neutrino (KATRIN) experiment consists of a multi-pixel silicon p-i-n-diode array, custom readout electronics, two superconducting solenoid magnets, an ultra high vacuum system, a high vacuum system, calibration and monitoring devices, a scintillating veto, and a custom data-acquisition system, It is designed to detect the low-energy electrons selected by the KATRIN main spectrometer. We describe the system and summarize its performance after its final installation.

Focal-plane detector system for the KATRIN experiment

DOE PAGES

Amsbaugh, J. F.; Barrett, J.; Beglarian, A.; ...

2015-01-09

Here, the local plane detector system for the KArlsiuhe TRItium Neutrino (KATRIN) experiment consists of a multi-pixel silicon p-i-n-diode array, custom readout electronics, two superconducting solenoid magnets, an ultra high vacuum system, a high vacuum system, calibration and monitoring devices, a scintillating veto, and a custom data-acquisition system, It is designed to detect the low-energy electrons selected by the KATRIN main spectrometer. We describe the system and summarize its performance after its final installation.

A first comparison of the responses of a 4He-based fast-neutron detector and a NE-213 liquid-scintillator reference detector

NASA Astrophysics Data System (ADS)

Jebali, R.; Scherzinger, J.; Annand, J. R. M.; Chandra, R.; Davatz, G.; Fissum, K. G.; Friederich, H.; Gendotti, U.; Hall-Wilton, R.; Håkansson, E.; Kanaki, K.; Lundin, M.; Murer, D.; Nilsson, B.; Rosborg, A.; Svensson, H.

2015-09-01

A first comparison has been made between the pulse-shape discrimination characteristics of a novel 4He-based pressurized scintillation detector and a NE-213 liquid-scintillator reference detector using an Am/Be mixed-field neutron and gamma-ray source and a high-resolution scintillation-pulse digitizer. In particular, the capabilities of the two fast neutron detectors to discriminate between neutrons and gamma-rays were investigated. The NE-213 liquid-scintillator reference cell produced a wide range of scintillation-light yields in response to the gamma-ray field of the source. In stark contrast, due to the size and pressure of the 4He gas volume, the 4He-based detector registered a maximum scintillation-light yield of 750keVee to the same gamma-ray field. Pulse-shape discrimination for particles with scintillation-light yields of more than 750keVee was excellent in the case of the 4He-based detector. Above 750keVee its signal was unambiguously neutron, enabling particle identification based entirely upon the amount of scintillation light produced.

Balloon flight test of a Compton telescope based on scintillators with silicon photomultiplier readouts

NASA Astrophysics Data System (ADS)

Bloser, P. F.; Legere, J. S.; Bancroft, C. M.; Ryan, J. M.; McConnell, M. L.

2016-03-01

We present the results of the first high-altitude balloon flight test of a concept for an advanced Compton telescope making use of modern scintillator materials with silicon photomultiplier (SiPM) readouts. There is a need in the fields of high-energy astronomy and solar physics for new medium-energy gamma-ray ( 0.4-10 MeV) detectors capable of making sensitive observations of both line and continuum sources over a wide dynamic range. A fast scintillator-based Compton telescope with SiPM readouts is a promising solution to this instrumentation challenge, since the fast response of the scintillators permits both the rejection of background via time-of-flight (ToF) discrimination and the ability to operate at high count rates. The Solar Compton Telescope (SolCompT) prototype presented here was designed to demonstrate stable performance of this technology under balloon-flight conditions. The SolCompT instrument was a simple two-element Compton telescope, consisting of an approximately one-inch cylindrical stilbene crystal for a scattering detector and a one-inch cubic LaBr3:Ce crystal for a calorimeter detector. Both scintillator detectors were read out by 2×2 arrays of Hamamatsu S11828-3344 MPPC devices. Custom front-end electronics provided optimum signal rise time and linearity, and custom power supplies automatically adjusted the SiPM bias voltage to compensate for temperature-induced gain variations. A tagged calibration source, consisting of 240 nCi of 60Co embedded in plastic scintillator, was placed in the field of view and provided a known source of gamma rays to measure in flight. The SolCompT balloon payload was launched on 24 August 2014 from Fort Sumner, NM, and spent 3.75 h at a float altitude of 123,000 ft. The instrument performed well throughout the flight. After correcting for small ( 10%) residual gain variations, we measured an in-flight ToF resolution of 760 ps (FWHM). Advanced scintillators with SiPM readouts continue to show great promise for future gamma-ray instruments.

First upper limits on the radar cross section of cosmic-ray induced extensive air showers

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

Abbasi, R. U.; Abe, M.; Abou Bakr Othman, M.

TARA (Telescope Array Radar) is a cosmic ray radar detection experiment colocated with Telescope Array, the conventional surface scintillation detector (SD) and fluorescence telescope detector (FD) near Delta, Utah, U.S.A. Furthermore, the TARA detector combines a 40 kW, 54.1 MHz VHF transmitter and high-gain transmitting antenna which broadcasts the radar carrier over the SD array and within the FD field of view, towards a 250 MS/s DAQ receiver. TARA has been collecting data since 2013 with the primary goal of observing the radar signatures of extensive air showers (EAS). Simulations indicate that echoes are expected to be short in durationmore » (~10 µs) and exhibit rapidly changing frequency, with rates on the order 1 MHz/µs. The EAS radar cross-section (RCS) is currently unknown although it is the subject of over 70 years of speculation. One novel signal search technique is described in which the expected radar echo of a particular air shower is used as a matched filter template and compared to waveforms obtained by triggering the radar DAQ using the Telescope Array fluorescence detector. No evidence for the scattering of radio frequency radiation by EAS is obtained to date. Finally, we report the first quantitative RCS upper limits using EAS that triggered the Telescope Array Fluorescence Detector.« less

First upper limits on the radar cross section of cosmic-ray induced extensive air showers

DOE PAGES

Abbasi, R. U.; Abe, M.; Abou Bakr Othman, M.; ...

2016-11-19

TARA (Telescope Array Radar) is a cosmic ray radar detection experiment colocated with Telescope Array, the conventional surface scintillation detector (SD) and fluorescence telescope detector (FD) near Delta, Utah, U.S.A. Furthermore, the TARA detector combines a 40 kW, 54.1 MHz VHF transmitter and high-gain transmitting antenna which broadcasts the radar carrier over the SD array and within the FD field of view, towards a 250 MS/s DAQ receiver. TARA has been collecting data since 2013 with the primary goal of observing the radar signatures of extensive air showers (EAS). Simulations indicate that echoes are expected to be short in durationmore » (~10 µs) and exhibit rapidly changing frequency, with rates on the order 1 MHz/µs. The EAS radar cross-section (RCS) is currently unknown although it is the subject of over 70 years of speculation. One novel signal search technique is described in which the expected radar echo of a particular air shower is used as a matched filter template and compared to waveforms obtained by triggering the radar DAQ using the Telescope Array fluorescence detector. No evidence for the scattering of radio frequency radiation by EAS is obtained to date. Finally, we report the first quantitative RCS upper limits using EAS that triggered the Telescope Array Fluorescence Detector.« less

Improved DQE by means of X-ray spectra and scintillator optimization for FFDM

NASA Astrophysics Data System (ADS)

Job, Isaias D.; Taie-Nobraie, Nima; Colbeth, Richard E.; Mollov, Ivan; Gray, Keith D.; Webb, Chris; Pavkovich, John M.; Zoghi, Fred; Tognina, Carlo A.; Roos, Pieter G.

2012-03-01

The focus of this work was to improve the DQE performance of a full-field digital mammography (FFDM) system by means of selecting an optimal X-ray tube anode-filter combination in conjunction with an optimal scintillator configuration. The flat panel detector in this work is a Varian PaxScan 3024M. The detector technology is comprised of a 2816 row × 3584 column amorphous silicon (a-Si) photodiode array with a pixel pitch of 83μm. The scintillator is cesium iodide and is deposited directly onto the photodiode array and available with configurable optical and x-ray properties. Two X-ray beam spectra were generated with the anode/filter combinations, Molybdenum/Molybdenum (Mo/Mo) and Tungsten/Aluminum (W/Al), to evaluate the imaging performance of two types of scintillators, high resolution (HR) type and high light output (HL) type. The results for the HR scintillator with W/Al anode-filter (HRW/ Al) yielded a DQE(0) of 67%, while HR-Mo/Mo was lower with a DQE(0) of 50%. In addition, the DQE(0) of the HR-W/Al configuration was comparable to the DQE(0) of the HL-Mo/Mo configuration. The significance of this result is the HR type scintillator yields about twice the light output with the W/Al spectrum, at about half the dose, as compared to the Mo/Mo spectrum. The light output or sensitivity was measured in analog-to-digital convertor units (ADU) per dose. The sensitivities (ADU/uGy) were 8.6, 16.8 and 25.4 for HR-Mo/Mo, HR-W/Al, HL-Mo/Mo, respectively. The Nyquist frequency for the 83 μm pixel is 6 lp/mm. The MTF at 5 lp/mm for HR-Mo/Mo and HR-W/Al were equivalent at 37%, while the HL-Mo/Mo MTF was 24%. According to the DQE metric, the more favorable anodefilter combination was W/Al with the HR scintillator. Future testing will evaluate the HL-W/Al configuration, as well as other x-ray filters materials and other scintillator optimizations. While higher DQE values were achieved, the more general conclusion is that the imaging performance can be tuned as required by the application by modifying optical and x-ray properties of the scintillator to match the spectral output of the chosen anode-filter combination.

A SiPM-based isotropic-3D PET detector X'tal cube with a three-dimensional array of 1 mm(3) crystals.

PubMed

Yamaya, Taiga; Mitsuhashi, Takayuki; Matsumoto, Takahiro; Inadama, Naoko; Nishikido, Fumihiko; Yoshida, Eiji; Murayama, Hideo; Kawai, Hideyuki; Suga, Mikio; Watanabe, Mitsuo

2011-11-07

We are developing a novel, general purpose isotropic-3D PET detector X'tal cube which has high spatial resolution in all three dimensions. The research challenge for this detector is implementing effective detection of scintillation photons by covering six faces of a segmented crystal block with silicon photomultipliers (SiPMs). In this paper, we developed the second prototype of the X'tal cube for a proof-of-concept. We aimed at realizing an ultimate detector with 1.0 mm(3) cubic crystals, in contrast to our previous development using 3.0 mm(3) cubic crystals. The crystal block was composed of a 16 × 16 × 16 array of lutetium gadolinium oxyorthosilicate (LGSO) crystals 0.993 × 0.993 × 0.993 mm(3) in size. The crystals were optically glued together without inserting any reflector inside and 96 multi-pixel photon counters (MPPCs, S10931-50P, i.e. six faces each with a 4 × 4 array of MPPCs), each having a sensitive area of 3.0 × 3.0 mm(2), were optically coupled to the surfaces of the crystal block. Almost all 4096 crystals were identified through Anger-type calculation due to the finely adjusted reflector sheets inserted between the crystal block and light guides. The reflector sheets, which formed a belt of 0.5 mm width, were placed to cover half of the crystals of the second rows from the edges in order to improve identification performance of the crystals near the edges. Energy resolution of 12.7% was obtained at 511 keV with almost uniform light output for all crystal segments thanks to the effective detection of the scintillation photons.

Photodetection Characterization of SiPM Technologies for their Application in Scintillator based Neutron Detectors

NASA Astrophysics Data System (ADS)

Kumar, S.; Durini, D.; Degenhardt, C.; van Waasen, S.

2018-01-01

Small-angle neutron scattering (SANS) experiments have become one of the most important techniques in the investigation of the properties of material on the atomic scale. Until 2001, nearly exclusively 3He-based detectors were used for neutron detection in these experiments, but due to the scarcity of 3He and its steeply rising price, researchers started to look for suitable alternatives. Scintillation based solid state detectors appeared as a prominent alternative. Silicon photomultipliers (SiPM), having single photon resolution, lower bias voltages compared to photomultiplier tubes (PMT), insensitivity to magnetic fields, low cost, possibility of modular design and higher readout rates, have the potential of becoming a photon detector of choice in scintillator based neutron detectors. The major concerns for utilizing the SiPM technology in this kind of applications are the increase in their noise performance and the decrease in their photon detection efficiency (PDE) due to direct exposure to neutrons. Here, a detailed comparative analysis of the PDE performance in the range between UV and NIR parts of the spectra for three different SiPM technologies, before and after irradiation with cold neutrons, has been carried out. For this investigation, one digital and two analog SiPM arrays were irradiated with 5Å wavelength cold neutrons and up to a dose of 6×1012 n/cm2 at the KWS-1 instrument of the Heinz Maier-Leibnitz Zentrum (MLZ) in Garching, Germany.

Towards monolithic scintillator based TOF-PET systems: practical methods for detector calibration and operation.

PubMed

Borghi, Giacomo; Tabacchini, Valerio; Schaart, Dennis R

2016-07-07

Gamma-ray detectors based on thick monolithic scintillator crystals can achieve spatial resolutions  <2 mm full-width-at-half-maximum (FWHM) and coincidence resolving times (CRTs) better than 200 ps FWHM. Moreover, they provide high sensitivity and depth-of-interaction (DOI) information. While these are excellent characteristics for clinical time-of-flight (TOF) positron emission tomography (PET), the application of monolithic scintillators has so far been hampered by the lengthy and complex procedures needed for position- and time-of-interaction estimation. Here, the algorithms previously developed in our group are revised to make the calibration and operation of a large number of monolithic scintillator detectors in a TOF-PET system practical. In particular, the k-nearest neighbor (k-NN) classification method for x,y-position estimation is accelerated with an algorithm that quickly preselects only the most useful reference events, reducing the computation time for position estimation by a factor of ~200 compared to the previously published k-NN 1D method. Also, the procedures for estimating the DOI and time of interaction are revised to enable full detector calibration by means of fan-beam or flood irradiations only. Moreover, a new technique is presented to allow the use of events in which some of the photosensor pixel values and/or timestamps are missing (e.g. due to dead time), so as to further increase system sensitivity. The accelerated methods were tested on a monolithic scintillator detector specifically developed for clinical PET applications, consisting of a 32 mm  ×  32 mm  ×  22 mm LYSO : Ce crystal coupled to a digital photon counter (DPC) array. This resulted in a spatial resolution of 1.7 mm FWHM, an average DOI resolution of 3.7 mm FWHM, and a CRT of 214 ps. Moreover, the possibility of using events missing the information of up to 16 out of 64 photosensor pixels is shown. This results in only a small deterioration of the detector performance.

The KASCADE-Grande experiment

NASA Astrophysics Data System (ADS)

Apel, W. D.; Arteaga, J. C.; Badea, A. F.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Buchholz, P.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Finger, M.; Fuhrmann, D.; Ghia, P. L.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Kickelbick, D.; Klages, H. O.; Link, K.; łuczak, P.; Ludwig, M.; Mathes, H. J.; Mayer, H. J.; Melissas, M.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Palmieri, N.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schröder, F.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.

2010-08-01

KASCADE-Grande is the enlargement of the KASCADE extensive air shower detector, realized to expand the cosmic ray studies from the previous 10 14-10 17 eV primary energy range to 10 18 eV. This is performed by extending the area covered by the KASCADE electromagnetic array from 200×200 to 700×700 m 2 by means of 37 scintillator detector stations of 10 m 2 area each. This new array is named Grande and provides measurements of the all-charged particle component of extensive air showers ( Nch), while the original KASCADE array particularly provides information on the muon content (Nμ). Additional dense compact detector set-ups being sensitive to energetic hadrons and muons are used for data consistency checks and calibration purposes. The performance of the Grande array and its integration into the entire experimental complex is discussed. It is demonstrated that the overall observable resolutions are adequate to meet the physical requirements of the measurements, i.e. primary energy spectrum and elemental composition studies in the primary cosmic ray energy range of 10 16-10 18 eV.

A compact pulse shape discriminator module for large neutron detector arrays

NASA Astrophysics Data System (ADS)

Venkataramanan, S.; Gupta, Arti; Golda, K. S.; Singh, Hardev; Kumar, Rakesh; Singh, R. P.; Bhowmik, R. K.

2008-11-01

A cost-effective high-performance pulse shape discriminator module has been developed to process signals from organic liquid scintillator-based neutron detectors. This module is especially designed for the large neutron detector array used for studies of nuclear reaction dynamics at the Inter University Accelerator Center (IUAC). It incorporates all the necessary pulse processing circuits required for neutron spectroscopy in a novel fashion by adopting the zero crossover technique for neutron-gamma (n- γ) pulse shape discrimination. The detailed layout of the circuit and different features of the module are described in the present paper. The quality of n- γ separation obtained with this electronics is much better than that of commercial modules especially in the low-energy region. The results obtained with our module are compared with similar setups available in other laboratories.

"Phoswich Wall": A charged-particle detector array for inverse-kinematic reactions with the Gretina/GRETA γ-ray arrays

NASA Astrophysics Data System (ADS)

Sarantites, D. G.; Reviol, W.; Elson, J. M.; Kinnison, J. E.; Izzo, C. J.; Manfredi, J.; Liu, J.; Jung, H. S.; Goerres, J.

2015-08-01

A high-efficiency, forward-hemisphere detector system for light charged particles and low-Z heavy ions, as obtained in an accelerator experiment, is described. It consists of four 8×8 pixel multianode photomultiplier tubes with 2.2-mm thick CsI(Tl) and 12 -μm thick fast-plastic scintillation detectors. Its phoswich structure allows individual Z resolution for 1H, 4He, 7Li, 4He+4He, 9Be, 11B, 12C, and 14N ions, which are target-like fragments detected in strongly inverse kinematics. The device design has been optimized for use with a 4π γ-ray array, and the main applications are transfer reactions and Coulomb excitation. A high-angular resolution for the detection of the target-like fragments is achieved which permits angular distributions to be measured in the rest frame of the projectile-like fragment with a resolution of ~ 2 °.

Investigation of spatial resolution improvement by use of a mouth-insert detector in the helmet PET scanner.

PubMed

Ahmed, Abdella M; Tashima, Hideaki; Yamaya, Taiga

2018-03-01

The dominant factor limiting the intrinsic spatial resolution of a positron emission tomography (PET) system is the size of the crystal elements in the detector. To increase sensitivity and achieve high spatial resolution, it is essential to use advanced depth-of-interaction (DOI) detectors and arrange them close to the subject. The DOI detectors help maintain high spatial resolution by mitigating the parallax error caused by the thickness of the scintillator near the peripheral regions of the field-of-view. As an optimal geometry for a brain PET scanner, with high sensitivity and spatial resolution, we proposed and developed the helmet-chin PET scanner using 54 four-layered DOI detectors consisting of a 16 × 16 × 4 array of GSOZ scintillator crystals with dimensions of 2.8 × 2.8 × 7.5 mm 3 . All the detectors used in the helmet-chin PET scanner had the same spatial resolution. In this study, we conducted a feasibility study of a new add-on detector arrangement for the helmet PET scanner by replacing the chin detector with a segmented crystal cube, having high spatial resolution in all directions, which can be placed inside the mouth. The crystal cube (which we have named the mouth-insert detector) has an array of 20 × 20 × 20 LYSO crystal segments with dimensions of 1 × 1 × 1 mm 3 . Thus, the scanner is formed by the combination of the helmet and mouth-insert detectors, and is referred to as the helmet-mouth-insert PET scanner. The results show that the helmet-mouth-insert PET scanner has comparable sensitivity and improved spatial resolution near the center of the hemisphere, compared to the helmet-chin PET scanner.

From The Pierre Auger Observatory to AugerPrime

NASA Astrophysics Data System (ADS)

Parra, Alejandra; Martínez Bravo, Oscar; Pierre Auger Collaboration

2017-06-01

In the present work we report the principal motivation and reasons for the new stage of the Pierre Auger Observatory, AugerPrime. This upgrade has as its principal goal to clarify the origin of the highest energy cosmic rays through improvement in studies of the mass composition. To accomplished this goal, AugerPrime will use air shower universality, which states that extensive air showers can be completely described by three parameters: the primary energy E 0, the atmospheric shower depth of maximum X max, and the number of muons, Nμ . The Auger Collaboration has planned to complement its surface array (SD), based on water-Cherenkov detectors (WCD) with scintillator detectors, calls SSD (Scintillator Surface Detector). These will be placed at the top of each WCD station. The SSD will allow a shower to shower analysis, instead of the statistical analysis that the Observatory has previously done, to determine the mass composition of the primary particle by the electromagnetic to muonic ratio.

Long-distance transmission of light in a scintillator-based radiation detector

DOEpatents

Dowell, Jonathan L.; Talbott, Dale V.; Hehlen, Markus P.

2017-07-11

Scintillator-based radiation detectors capable of transmitting light indicating the presence of radiation for long distances are disclosed herein. A radiation detector can include a scintillator layer and a light-guide layer. The scintillator layer is configured to produce light upon receiving incident radiation. The light-guide layer is configured to receive light produced by the scintillator layer and either propagate the received light through the radiation detector or absorb the received light and emit light, through fluorescence, that is propagated through the radiation detector. A radiation detector can also include an outer layer partially surrounding the scintillator layer and light-guide layer. The index of refraction of the light-guide layer can be greater than the index of refraction of adjacent layers.

1987 Nuclear Science Symposium, 34th, and 1987 Symposium on Nuclear Power Systems, 19th, San Francisco, CA, Oct. 21-23, 1987, Proceedings

NASA Astrophysics Data System (ADS)

Armantrout, Guy A.

1988-02-01

The present conference consideres topics in radiation detectors, advanced electronic circuits, data acquisition systems, radiation detector systems, high-energy and nuclear physics radiation detection, spaceborne instrumentation, health physics and environmental radiation detection, nuclear medicine, nuclear well logging, and nuclear reactor instrumentation. Attention is given to the response of scintillators to heavy ions, phonon-mediated particle detection, ballistic deficits in pulse-shaping amplifiers, fast analog ICs for particle physics, logic cell arrays, the CERN host interface, high performance data buses, a novel scintillating glass for high-energy physics applications, background events in microchannel plates, a tritium accelerator mass spectrometer, a novel positron tomograph, advancements in PET, cylindrical positron tomography, nuclear techniques in subsurface geology, REE borehole neutron activation, and a continuous tritium monitor for aqueous process streams.

Gas Scintillation Proportional Counters for High-Energy X-ray Astronomy

NASA Technical Reports Server (NTRS)

Gubarev, Mikhail; Ramsey, Brian; Apple, Jeffery

2003-01-01

A focal plane array of high-pressure gas scintillation proportional counters (GSPC) for a balloon-borne hard-x-ray telescope is under development at the Marshall Space Flight Center. These detectors have an active area of approx. 20 sq cm, and are filled with a high pressure (10(exp 6) Pa) xenon-helium mixture. Imaging is via crossed-grid position-sensitive phototubes sensitive in the UV region. The performance of the GSPC is well matched to that of the telescopes x-ray optics which have response to 75 keV and a focal spot size of approx. 500 microns. The detector s energy resolution, 4% FWHM at 60 keV, is adequate for resolving the broad spectral lines of astrophysical importance and for accurate continuum measurements. Full details of the instrument and its performance will be provided.

Application of large area SiPMs for the readout of a plastic scintillator based timing detector

NASA Astrophysics Data System (ADS)

Betancourt, C.; Blondel, A.; Brundler, R.; Dätwyler, A.; Favre, Y.; Gascon, D.; Gomez, S.; Korzenev, A.; Mermod, P.; Noah, E.; Serra, N.; Sgalaberna, D.; Storaci, B.

2017-11-01

In this study an array of eight 6 mm × 6 mm area SiPMs was coupled to the end of a long plastic scintillator counter which was exposed to a 2.5 GeV/c muon beam at the CERN PS. Timing characteristics of bars with dimensions 150 cm × 6 cm × 1 cm and 120 cm × 11 cm × 2.5 cm have been studied. An 8-channel SiPM anode readout ASIC (MUSIC R1) based on a novel low input impedance current conveyor has been used to read out and amplify SiPMs independently and sum the signals at the end. Prospects for applications in large-scale particle physics detectors with timing resolution below 100 ps are provided in light of the results.

a High-Precision Branching-Ratio Measurement for the Superallowed β+ Emitter 74Rb

NASA Astrophysics Data System (ADS)

Dunlop, R.; Chagnon-Lessard, S.; Finlay, P.; Garrett, P. E.; Hadinia, B.; Leach, K. G.; Svensson, C. E.; Wong, J.; Ball, G.; Garnsworthy, A. B.; Glister, J.; Hackman, G.; Tardiff, E. R.; Triambak, S.; Williams, S. J.; Leslie, J. R.; Andreoiu, C.; Chester, A.; Cross, D.; Starosta, K.; Yates, S. W.; Zganjar, E. F.

2013-03-01

Precision measurements of superallowed Fermi beta decay allow for tests of the Cabibbo-Kobayashi-Maskawa matrix (CKM) unitarity, the conserved vector current hypothesis, and the magnitude of isospin-symmetry-breaking effects in nuclei. A high-precision measurement of the branching ratio for the β+ decay of 74Rb has been performed at the Isotope Separator and ACcelerator (ISAC) facility at TRIUMF. The 8π spectrometer, an array of 20 close-packed HPGe detectors, was used to detect gamma rays emitted following the decay of 74Rb. PACES, an array of 5 Si(Li) detectors, was used to detect emitted conversion electrons, while SCEPTAR, an array of plastic scintillators, was used to detect emitted beta particles. A total of 51γ rays have been identified following the decay of 21 excited states in the daughter nucleus 74Kr.

Indirect X-ray Detectors Based on Inkjet-Printed Photodetectors with a Screen-Printed Scintillator Layer.

PubMed

Oliveira, Juliana; Correia, Vitor; Sowade, Enrico; Etxebarria, Ikerne; Rodriguez, Raul D; Mitra, Kalyan Y; Baumann, Reinhard R; Lanceros-Mendez, Senentxu

2018-04-18

Organic photodetectors (PDs) based on printing technologies will allow to expand the current field of PD applications toward large-area and flexible applications in areas such as medical imaging, security, and quality control, among others. Inkjet printing is a powerful digital tool for the deposition of smart and functional materials on various substrates, allowing the development of electronic devices such as PDs on various substrates. In this work, inkjet-printed PD arrays, based on the organic thin-film transistor architecture, have been developed and applied for the indirect detection of X-ray radiation using a scintillator ink as an X-ray absorber. The >90% increase of the photocurrent of the PDs under X-ray radiation, from about 53 nA without the scintillator film to about 102 nA with the scintillator located on top of the PD, proves the suitability of the developed printed device for X-ray detection applications.

Electrical delay line multiplexing for pulsed mode radiation detectors

NASA Astrophysics Data System (ADS)

Vinke, Ruud; Yeom, Jung Yeol; Levin, Craig S.

2015-04-01

Medical imaging systems are composed of a large number of position sensitive radiation detectors to provide high resolution imaging. For example, whole-body Positron Emission Tomography (PET) systems are typically composed of thousands of scintillation crystal elements, which are coupled to photosensors. Thus, PET systems greatly benefit from methods to reduce the number of data acquisition channels, in order to reduce the system development cost and complexity. In this paper we present an electrical delay line multiplexing scheme that can significantly reduce the number of readout channels, while preserving the signal integrity required for good time resolution performance. We experimented with two 4 × 4 LYSO crystal arrays, with crystal elements having 3 mm × 3 mm × 5 mm and 3 mm × 3 mm × 20 mm dimensions, coupled to 16 Hamamatsu MPPC S10931-050P SiPM elements. Results show that each crystal could be accurately identified, even in the presence of scintillation light sharing and inter-crystal Compton scatter among neighboring crystal elements. The multiplexing configuration degraded the coincidence timing resolution from ∼243 ps FWHM to ∼272 ps FWHM when 16 SiPM signals were combined into a single channel for the 4 × 4 LYSO crystal array with 3 mm × 3 mm × 20 mm crystal element dimensions, in coincidence with a 3 mm × 3 mm × 5 mm LYSO crystal pixel. The method is flexible to allow multiplexing configurations across different block detectors, and is scalable to an entire ring of detectors.

Single transmission-line readout method for silicon photomultiplier based time-of-flight and depth-of-interaction PET

NASA Astrophysics Data System (ADS)

Ko, Guen Bae; Lee, Jae Sung

2017-03-01

We propose a novel single transmission-line readout method for whole-body time-of-flight positron emission tomography applications, without compromising on performance. The basic idea of the proposed multiplexing method is the addition of a specially prepared tag signal ahead of the scintillation pulse. The tag signal is a square pulse that encodes photon arrival time and channel information. The 2D position of a silicon photomultiplier (SiPM) array is encoded by the specific width and height of the tag signal. A summing amplifier merges the tag and scintillation signals of each channel, and the final output signal can be acquired with a one-channel digitizer. The feasibility and performance of the proposed method were evaluated using a 1:1 coupled detector consisting of 4  ×  4 array of LGSO crystals and 16 channel SiPM. The sixteen 3 mm LGSO crystals were clearly separated in the crystal-positioning map with high reliability. The average energy resolution and coincidence resolving time were 11.31  ±  0.55% and 264.7  ±  10.7 ps, respectively. We also proved that the proposed method does not degrade timing performance with increasing multiplexing ratio. The two types of LGSO crystals (L0.95GSO and L0.20GSO) in phoswich detector were also clearly identified with the high-reliability using pulse shape discrimination, thanks to the well-preserved pulse shape information. In conclusion, the proposed multiplexing method allows decoding of the 3D interaction position of gamma rays in the scintillation detector with single-line readout.

Single transmission-line readout method for silicon photomultiplier based time-of-flight and depth-of-interaction PET.

PubMed

Ko, Guen Bae; Lee, Jae Sung

2017-03-21

We propose a novel single transmission-line readout method for whole-body time-of-flight positron emission tomography applications, without compromising on performance. The basic idea of the proposed multiplexing method is the addition of a specially prepared tag signal ahead of the scintillation pulse. The tag signal is a square pulse that encodes photon arrival time and channel information. The 2D position of a silicon photomultiplier (SiPM) array is encoded by the specific width and height of the tag signal. A summing amplifier merges the tag and scintillation signals of each channel, and the final output signal can be acquired with a one-channel digitizer. The feasibility and performance of the proposed method were evaluated using a 1:1 coupled detector consisting of 4  ×  4 array of LGSO crystals and 16 channel SiPM. The sixteen 3 mm LGSO crystals were clearly separated in the crystal-positioning map with high reliability. The average energy resolution and coincidence resolving time were 11.31  ±  0.55% and 264.7  ±  10.7 ps, respectively. We also proved that the proposed method does not degrade timing performance with increasing multiplexing ratio. The two types of LGSO crystals (L 0.95 GSO and L 0.20 GSO) in phoswich detector were also clearly identified with the high-reliability using pulse shape discrimination, thanks to the well-preserved pulse shape information. In conclusion, the proposed multiplexing method allows decoding of the 3D interaction position of gamma rays in the scintillation detector with single-line readout.

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

Danevich, F. A., E-mail: danevich@kinr.kiev.ua; Boiko, R. S.; Chernyak, D. M.

The LUMTNEU program aims at performing a pilot experiment on 0ν2β decay of {sup 100}Mo using radiopure ZnMoO{sub 4} crystals enriched in {sup 100}Mo operated as cryogenic scintillating bolometers. Large volume ZnMoO{sub 4} crystal scintillators (∼ 0.3 kg) were developed and tested showing high performance in terms of radiopurity, energy resolution and α/β particle discrimination capability. Zinc molybdate crystal scintillators enriched in {sup 100}Mo were grown for the first time by the low-thermal-gradient Czochralski technique with a high crystal yield and an acceptable level of enriched molybdenum irrecoverable losses. A background level of ∼ 0.5 counts/(yr keV ton) in the regionmore » of interest can be reached in a large detector array thanks to the excellent detectors radiopurity and particle discrimination capability, suppression of randomly coinciding events by pulse-shape analysis, and anticoincidence cut. These results pave the way to future sensitive searches based on the LUMTNEU technology, capable of approachingand exploring the inverted hierarchy region of the neutrino mass pattern.« less

Apparatus and method for temperature correction and expanded count rate of inorganic scintillation detectors

DOEpatents

Ianakiev, Kiril D [Los Alamos, NM; Hsue, Sin Tao [Santa Fe, NM; Browne, Michael C [Los Alamos, NM; Audia, Jeffrey M [Abiquiu, NM

2006-07-25

The present invention includes an apparatus and corresponding method for temperature correction and count rate expansion of inorganic scintillation detectors. A temperature sensor is attached to an inorganic scintillation detector. The inorganic scintillation detector, due to interaction with incident radiation, creates light pulse signals. A photoreceiver processes the light pulse signals to current signals. Temperature correction circuitry that uses a fast light component signal, a slow light component signal, and the temperature signal from the temperature sensor to corrected an inorganic scintillation detector signal output and expanded the count rate.

Preclinical positron emission tomography scanner based on a monolithic annulus of scintillator: initial design study.

PubMed

Stolin, Alexander V; Martone, Peter F; Jaliparthi, Gangadhar; Raylman, Raymond R

2017-01-01

Positron emission tomography (PET) scanners designed for imaging of small animals have transformed translational research by reducing the necessity to invasively monitor physiology and disease progression. Virtually all of these scanners are based on the use of pixelated detector modules arranged in rings. This design, while generally successful, has some limitations. Specifically, use of discrete detector modules to construct PET scanners reduces detection sensitivity and can introduce artifacts in reconstructed images, requiring the use of correction methods. To address these challenges, and facilitate measurement of photon depth-of-interaction in the detector, we investigated a small animal PET scanner (called AnnPET) based on a monolithic annulus of scintillator. The scanner was created by placing 12 flat facets around the outer surface of the scintillator to accommodate placement of silicon photomultiplier arrays. Its performance characteristics were explored using Monte Carlo simulations and sections of the NEMA NU4-2008 protocol. Results from this study revealed that AnnPET's reconstructed spatial resolution is predicted to be [Formula: see text] full width at half maximum in the radial, tangential, and axial directions. Peak detection sensitivity is predicted to be 10.1%. Images of simulated phantoms (mini-hot rod and mouse whole body) yielded promising results, indicating the potential of this system for enhancing PET imaging of small animals.

High-Energy Particle Showers Observed at Ground Level in Coincidence with Downward Lightning Leaders at the Telescope Array Observatory

NASA Astrophysics Data System (ADS)

Belz, John; Abbasi, Rasha; Le Von, Ryan; Krehbiel, Paul; Remington, Jackson; Rison, William

Terrestrial Gamma Ray Flashes (TGFs) detected by satellite observations have been shown to be generated by upward propagating negative leaders at altitudes of about 10 to 12 km above Mean Sea Level (MSL), and have durations ranging between a few hundred microseconds and a few milliseconds. The Telescope Array Cosmic Ray observatory, designed to observe air showers induced by ultra high energy cosmic rays, includes a surface scintillator detector (SD) covering approximately 700 square kilometers on a 1.2 km grid. Following the observation of anomalous SD triggers correlated with local lightning activity, a Lightning Mapping Array (LMA) and slow electric field antenna were installed at the TA site in order to characterize the lightning associated with these anomalous triggers. In this talk, we present evidence that the anomalous triggers are produced during the initial breakdown phase of fast, downward propagating, negative leaders above the detectors which produced the triggers. The durations of the high energy radiation are a few hundred microseconds, similar to satellite observations of TGFs. The triggers were produced within a few hundred microseconds of the initiation of the leaders, when the leaders were at an altitude of about 3 to 4 km MSL. The TA scintillation detectors are not optimized for gamma ray detection, however we present the results of simulations demonstrating that the fluxes observed are consistent with this picture. We conclude that the anomalous triggers observed by TA are clearly due to high energy radiation produced by the fast downward propagating negative leaders, and are probably downward-directed TGFs.

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

NASA Astrophysics Data System (ADS)

Weaver, Hannah; UCNTau Collaboration

2016-09-01

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

The PHOBOS detector at RHIC

NASA Astrophysics Data System (ADS)

Back, B. B.; Baker, M. D.; Barton, D. S.; Basilev, S.; Baum, R.; Betts, R. R.; Białas, A.; Bindel, R.; Bogucki, W.; Budzanowski, A.; Busza, W.; Carroll, A.; Ceglia, M.; Chang, Y.-H.; Chen, A. E.; Coghen, T.; Connor, C.; Czyż, W.; Dabrowski, B.; Decowski, M. P.; Despet, M.; Fita, P.; Fitch, J.; Friedl, M.; Gałuszka, K.; Ganz, R.; Garcia, E.; George, N.; Godlewski, J.; Gomes, C.; Griesmayer, E.; Gulbrandsen, K.; Gushue, S.; Halik, J.; Halliwell, C.; Haridas, P.; Hayes, A.; Heintzelman, G. A.; Henderson, C.; Hollis, R.; Hołyński, R.; Hofman, D.; Holzman, B.; Johnson, E.; Kane, J.; Katzy, J.; Kita, W.; Kotuła, J.; Kraner, H.; Kucewicz, W.; Kulinich, P.; Law, C.; Lemler, M.; Ligocki, J.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A.; Mülmenstädt, J.; Neal, M.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Patel, M.; Pernegger, H.; Plesko, M.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Ross, D.; Rosenberg, L.; Ryan, J.; Sanzgiri, A.; Sarin, P.; Sawicki, P.; Scaduto, J.; Shea, J.; Sinacore, J.; Skulski, W.; Steadman, S. G.; Stephans, G. S. F.; Steinberg, P.; Straczek, A.; Stodulski, M.; Strek, M.; Stopa, Z.; Sukhanov, A.; Surowiecka, K.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.; Zalewski, K.; Żychowski, P.; Phobos Collaboration

2003-03-01

This manuscript contains a detailed description of the PHOBOS experiment as it is configured for the Year 2001 running period. It is capable of detecting charged particles over the full solid angle using a multiplicity detector and measuring identified charged particles near mid-rapidity in two spectrometer arms with opposite magnetic fields. Both of these components utilize silicon pad detectors for charged particle detection. The minimization of material between the collision vertex and the first layers of silicon detectors allows for the detection of charged particles with very low transverse momenta, which is a unique feature of the PHOBOS experiment. Additional detectors include a time-of-flight wall which extends the particle identification range for one spectrometer arm, as well as sets of scintillator paddle and Cherenkov detector arrays for event triggering and centrality selection.

Highly improved operation of monolithic BGO-PET blocks

NASA Astrophysics Data System (ADS)

Gonzalez-Montoro, A.; Sanchez, F.; Majewski, S.; Zanettini, S.; Benlloch, J. M.; Gonzalez, A. J.

2017-11-01

In PET scanners both scintillation crystals and photosensors are key components defining the system's performance and cost. Original PET systems used BGO or NaI(Tl) scintillators but achieved limited performance due to its slow decay and relatively low light output. Moreover, NaI(Tl) has low stopping power for 511 keV annihilation photons. In this study we report the possibility to reintroduce BGO crystals, and in particular in the form of monolithic blocks, especially suitable for low-dose large-size PET scanners, offering significantly improved sensitivity at a highly reduced cost compared to LYSO type fast scintillators. We have studied the performance of a monolithic BGO block as large as 50 × 50 × 15 mm3 with black-painted lateral walls to reduce lights spread, enabling accurate photon depth of interaction (DOI) measurements. A directional optical layer, called retro-reflector, was coupled to the entrance face bouncing back the scintillation light in the direction of the emission source and, therefore, adding to the light signal while preserving the narrow light cone distribution. Four configurations namely 12 × 12 and 16 × 16 SiPM arrays (3 mm × 3 mm each) as photosensors, with or without a nanopattern treatment at the crystal exit face, have been studied. This structure consisted of a thin layer of a specific high refractive index material shaped with a periodic nanopattern, increasing the scintillation light extraction. The readout returned information for each SiPM row and column, characterizing the X-Y light distribution projections. We have studied the detector spatial resolution using collimated 22Na sources at normal incidence. The DOI resolution was evaluated using collimated gamma beams with lateral incidence. The overall best detector performance was obtained for the 16× 16 SiPM array offering higher readout granularity. We have determined the spatial resolution for 3 separated DOI layers, obtaining the best results for the DOI region near to the photosensor.

Scintillating fiber array for tagging post-bremsstrahlung electrons

NASA Astrophysics Data System (ADS)

Cole, Philip; Alef, Stefan; Reitz, Björn-Eric; Schmieden, Hartmut; Hannappel, Jürgen; Jude, Thomas; Sandri, Paolo Levi; BGO-OD Collaboration

2016-03-01

We seek to extract the kinematic fingerprints of baryon resonances by making use of a high-quality beam of linearly polarized photons at the BGO-OD experiment at ELSA (Bonn, German). We constructed a unique device for precisely determining the degree of polarization in the coherent bremsstrahlung peak. Deflection of post-bremsstrahlung electrons in the magnetic field of the photon tagger provides precise information on the energy and polarization of the bremsstrahlung photons. And thereby will constrain the overall kinematics of the final-state particles in all decay channels of the photoproduced baryon resonances. We designed, prototyped, built, calibrated, and have been operating a three-layered, multi-stranded, scintillating-fiber detector for ensuring the quality of the linearly polarization of the photon beam. The overlapping 2.00-mm scintillating fibers form an array giving ARGUS over 500 channels. The very befitting name harkens to the mythological all-seeing creature Argus Panoptes, the multi-eyed giant. Our work was supported through a Fulbright Scholarship Award and by the Deutsche Forschungsgemeinschaft through the Collaborative Research Center (Sonderforschungsbereich SFB/TR-16) of the universities in Bonn, Giessen and Bochum, Germany. NSF-PHY-1307340.

A novel depth-of-interaction block detector for positron emission tomography using a dichotomous orthogonal symmetry decoding concept.

PubMed

Zhang, Yuxuan; Yan, Han; Baghaei, Hossain; Wong, Wai-Hoi

2016-02-21

Conventionally, a dual-end depth-of-interaction (DOI) block detector readout requires two two-dimensional silicon photomultiplier (SiPM) arrays, one on top and one on the bottom, to define the XYZ positions. However, because both the top and bottom SiPM arrays are reading the same pixels, this creates information redundancy. We propose a dichotomous orthogonal symmetric (DOS) dual-end readout block detector design, which removes this redundancy by reducing the number of SiPMs and still achieves XY and DOI (Z) decoding for positron emission tomography (PET) block detector. Reflecting films are used within the block detector to channel photons going to the top of the block to go only in the X direction, and photons going to the bottom are channeled along the Y direction. Despite the unidirectional channeling on each end, the top readout provides both X and Y information using two one-dimensional SiPM arrays instead of a two-dimensional SiPM array; similarly, the bottom readout also provides both X and Y information with just two one-dimensional SiPM arrays. Thus, a total of four one-dimensional SiPM arrays (4  ×  N SiPMs) are used to decode the XYZ positions of the firing pixels instead of two two-dimensional SiPM arrays (2  ×  N  ×  N SiPMs), reducing the number of SiPM arrays per block from 2N(2) to 4 N for PET/MR or PET/CT systems. Moreover, the SiPM arrays on one end can be replaced by two regular photomultiplier tubes (PMTs), so that a block needs only 2 N SiPMs  +  2 half-PMTs; this hybrid-DOS DOI block detector can be used in PET/CT systems. Monte Carlo simulations were carried out to study the performance of our DOS DOI block detector design, including the XY-decoding quality, energy resolution, and DOI resolution. Both BGO and LSO scintillators were studied. We found that 4 mm pixels were well decoded for 5  ×  5 BGO and 9  ×  9 LSO arrays with 4 to 5 mm DOI resolution and 16-20% energy resolution. By adding light-channel decoding, we modified the DOS design to a high-resolution design, which resolved scintillator pixels smaller than the SiPM dimensions. Detector pixels of 2.4 mm were decoded for 8  ×  8 BGO and 15  ×  15 LSO arrays with 5 mm DOI resolution and 20-23% energy resolution. Time performance was also studied for the 8  ×  8 BGO and 15  ×  15 LSO HR-DOS arrays. The timing resolution for the corner and central crystals is 986  ±  122 ps and 1.89  ±  0.17 μs respectively with BGO, 137  ±  42 ps and 458  ±  67 ps respectively with LSO. Monte Carlo simulations with GATE/Geant4 demonstrated the feasibility of our DOS DOI block detector design. In conclusion, our novel design achieved good performance except the time performance while using fewer SiPMs and supporting electronic channels than the current non-DOI PET detectors. This novel design can significantly reduce the cost, heat, and readout complexity of DOI block detectors for PET/MR/CT systems that don't require the time-of-flight capability.

Monte Carlo simulation of simultaneous radiation detection in the hybrid tomography system ClearPET-XPAD3/CT

NASA Astrophysics Data System (ADS)

Dávila, H. Olaya; Sevilla, A. C.; Castro, H. F.; Martínez, S. A.

2016-07-01

Using the Geant4 based simulation framework SciFW1, a detailed simulation was performed for a detector array in the hybrid tomography prototype for small animals called ClearPET / XPAD, which was built in the Centre de Physique des Particules de Marseille. The detector system consists of an array of phoswich scintillation detectors: LSO (Lutetium Oxy-ortosilicate doped with cerium Lu2SiO5:Ce) and LuYAP (Lutetium Ortoaluminate of Yttrium doped with cerium Lu0.7Y0.3AlO3:Ce) for Positron Emission Tomography (PET) and hybrid pixel detector XPAD for Computed Tomography (CT). Simultaneous acquisition of deposited energy and the corresponding time - position for each recorded event were analyzed, independently, for both detectors. interference between detection modules for PET and CT. Information about amount of radiation reaching each phoswich crystal and XPAD detector using a phantom in order to study the effectiveness by radiation attenuation and influence the positioning of the radioactive source 22Na was obtained. The simulation proposed will improve distribution of detectors rings and interference values will be taken into account in the new versions of detectors.

A bench-top megavoltage fan-beam CT using CdWO4-photodiode detectors. I. System description and detector characterization.

PubMed

Rathee, S; Tu, D; Monajemi, T T; Rickey, D W; Fallone, B G

2006-04-01

We describe the components of a bench-top megavoltage computed tomography (MVCT) scanner that uses an 80-element detector array consisting of CdWO4 scintillators coupled to photodiodes. Each CdWO4 crystal is 2.75 x 8 x 10 mm3. The detailed design of the detector array, timing control, and multiplexer are presented. The detectors show a linear response to dose (dose rate was varied by changing the source to detector distance) with a correlation coefficient (R2) nearly unity with the standard deviation of signal at each dose being less than 0.25%. The attenuation of a 6 MV beam by solid water measured by this detector array indicates a small, yet significant spectral hardening that needs to be corrected before image reconstruction. The presampled modulation transfer function is strongly affected by the detector's large pitch and a large improvement can be obtained by reducing the detector pitch. The measured detective quantum efficiency at zero spatial frequency is 18.8% for 6 MV photons which will reduce the dose to the patient in MVCT applications. The detector shows a less than a 2% reduction in response for a dose of 24.5 Gy accumulated in 2 h; however, the lost response is recovered on the following day. A complete recovery can be assumed within the experimental uncertainty (standard deviation <0.5%); however, any smaller permanent damage could not be assessed.

Buried plastic scintillator muon telescope

NASA Astrophysics Data System (ADS)

Sanchez, F.; Medina-Tanco, G.A.; D'Olivo, J.C.; Paic, G.; Patino Salazar, M.E.; Nahmad-Achar, E.; Valdes Galicia, J.F.; Sandoval, A.; Alfaro Molina, R.; Salazar Ibarguen, H.; Diozcora Vargas Trevino, M.A.; Vergara Limon, S.; Villasenor, L.M.

Muon telescopes can have several applications, ranging from astrophysical to solar-terrestrial interaction studies, and fundamental particle physics. We show the design parameters, characterization and end-to-end simulations of a detector composed by a set of three parallel dual-layer scintillator planes, buried at fix depths ranging from 0.30 m to 3 m. Each layer is 4 m2 and is composed by 50 rectangular pixels of 4cm x 2 m, oriented at a 90 deg angle with respect to its companion layer. The scintillators are MINOS extruded polystyrene strips with two Bicron wavelength shifting fibers mounted on machined grooves. Scintillation light is collected by multi-anode PMTs of 64 pixels, accommodating two fibers per pixel. The front-end electronics has a time resolution of 7.5 nsec. Any strip signal above threshold opens a GPS-tagged 2 micro-seconds data collection window. All data, including signal and background, are saved to hard disk. Separation of extensive air shower signals from secondary cosmic-ray background muons and electrons is done offline using the GPS-tagged threefold coincidence signal from surface water cerenkov detectors located nearby in a triangular array. Cosmic-ray showers above 6 PeV are selected. The data acquisition system is designed to keep both, background and signals from extensive air showers for a detailed offline data.

High resolution phoswich gamma-ray imager utilizing monolithic MPPC arrays with submillimeter pixelized crystals

NASA Astrophysics Data System (ADS)

Kato, T.; Kataoka, J.; Nakamori, T.; Kishimoto, A.; Yamamoto, S.; Sato, K.; Ishikawa, Y.; Yamamura, K.; Kawabata, N.; Ikeda, H.; Kamada, K.

2013-05-01

We report the development of a high spatial resolution tweezers-type coincidence gamma-ray camera for medical imaging. This application consists of large-area monolithic Multi-Pixel Photon Counters (MPPCs) and submillimeter pixelized scintillator matrices. The MPPC array has 4 × 4 channels with a three-side buttable, very compact package. For typical operational gain of 7.5 × 105 at + 20 °C, gain fluctuation over the entire MPPC device is only ± 5.6%, and dark count rates (as measured at the 1 p.e. level) amount to <= 400 kcps per channel. We selected Ce-doped (Lu,Y)2(SiO4)O (Ce:LYSO) and a brand-new scintillator, Ce-doped Gd3Al2Ga3O12 (Ce:GAGG) due to their high light yield and density. To improve the spatial resolution, these scintillators were fabricated into 15 × 15 matrices of 0.5 × 0.5 mm2 pixels. The Ce:LYSO and Ce:GAGG scintillator matrices were assembled into phosphor sandwich (phoswich) detectors, and then coupled to the MPPC array along with an acrylic light guide measuring 1 mm thick, and with summing operational amplifiers that compile the signals into four position-encoded analog outputs being used for signal readout. Spatial resolution of 1.1 mm was achieved with the coincidence imaging system using a 22Na point source. These results suggest that the gamma-ray imagers offer excellent potential for applications in high spatial medical imaging.

Compact conscious animal positron emission tomography scanner

DOEpatents

Schyler, David J.; O'Connor, Paul; Woody, Craig; Junnarkar, Sachin Shrirang; Radeka, Veljko; Vaska, Paul; Pratte, Jean-Francois; Volkow, Nora

2006-10-24

A method of serially transferring annihilation information in a compact positron emission tomography (PET) scanner includes generating a time signal for an event, generating an address signal representing a detecting channel, generating a detector channel signal including the time and address signals, and generating a composite signal including the channel signal and similarly generated signals. The composite signal includes events from detectors in a block and is serially output. An apparatus that serially transfers annihilation information from a block includes time signal generators for detectors in a block and an address and channel signal generator. The PET scanner includes a ring tomograph that mounts onto a portion of an animal, which includes opposing block pairs. Each of the blocks in a block pair includes a scintillator layer, detection array, front-end array, and a serial encoder. The serial encoder includes time signal generators and an address signal and channel signal generator.

The pulse profile of the Crab pulsar in the energy range 45 keV-1.2 MeV

NASA Technical Reports Server (NTRS)

Wilson, R. B.; Fishman, G. J.

1983-01-01

The Crab Nebula pulsar (PSR 0531+21) is the best studied and most intense of the nontransient X-ray pulsars. However, since its spectrum drops rapidly with energy, a well-resolved pulse profile has not previously been obtained above 200 keV. In the hard X-ray and low-energy gamma-ray region, an accurate pulse profile can be obtained with a balloon-borne detector of sufficient area during a single transit of the source. A new measurement of the pulse profile of PSR 0531+21 in the energy range above 45 keV obtained with a large-area scintillation detector array is reported. The detector array was flown on a balloon launched from Palestine, Texas on 1980 October 6, reaching a float altitude 4.5 g/sq cm at 0230 UTC October 7. The primary objective of the experiment was to detect and study weak gamma-ray bursts.

The aCORN backscatter-suppressed beta spectrometer

DOE PAGES

Hassan, M. T.; Bateman, F.; Collett, B.; ...

2017-06-16

Backscatter of electrons from a beta detector, with incomplete energy deposition, can lead to undesirable effects in many types of experiments. We present and discuss the design and operation of a backscatter-suppressed beta spectrometer that was developed as part of a program to measure the electron–antineutrino correlation coefficient in neutron beta decay (aCORN). An array of backscatter veto detectors surrounds a plastic scintillator beta energy detector. The spectrometer contains an axial magnetic field gradient, so electrons are efficiently admitted but have a low probability for escaping back through the entrance after backscattering. Lastly, the design, construction, calibration, and performance ofmore » the spectrometer are discussed.« less

Simulated Performances of a Very High Energy Tomograph for Non-Destructive Characterization of large objects

NASA Astrophysics Data System (ADS)

Kistler, Marc; Estre, Nicolas; Merle, Elsa

2018-01-01

As part of its R&D activities on high-energy X-ray imaging for non-destructive characterization, the Nuclear Measurement Laboratory has started an upgrade of its imaging system currently implemented at the CEA-Cadarache center. The goals are to achieve a sub-millimeter spatial resolution and the ability to perform tomographies on very large objects (more than 100-cm standard concrete or 40-cm steel). This paper presentsresults on the detection part of the imaging system. The upgrade of the detection part needs a thorough study of the performance of two detectors: a series of CdTe semiconductor sensors and two arrays of segmented CdWO4 scintillators with different pixel sizes. This study consists in a Quantum Accounting Diagram (QAD) analysis coupled with Monte-Carlo simulations. The scintillator arrays are able to detect millimeter details through 140 cm of concrete, but are limited to 120 cm for smaller ones. CdTe sensors have lower but more stable performance, with a 0.5 mm resolution for 90 cm of concrete. The choice of the detector then depends on the preferred characteristic: the spatial resolution or the use on large volumes. The combination of the features of the source and the studies on the detectors gives the expected performance of the whole equipment, in terms of signal-over-noise ratio (SNR), spatial resolution and acquisition time.

Summary of Internship Experience for 2010 DHS/ORISE summer program

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

Pusateri, Elise; Descalle, Marie-Anne

2010-08-13

The U.S. Department of Homeland Security has deemed as a threat to national security the possibility of fissionable materials being concealed in intermodal cargo containers. Detecting these materials is critical to preventing nuclear proliferation and terrorism. Thus, several high-energy photon-based imaging applications are being developed to detect materials with Z>72 in such containers. In an initial study, an array made of plastic scintillator material was considered for a detector in combination with a bremsstrahlung sources. While plastic is a practical and cheap material to use, it has relatively poor energy resolution. When studying the full spectrum of available materials, Bimore » 4Ge 3O 12 (BGO) 2 was considered and was eventually chosen as the scintillation material for its high mass density which permits high spatial resolution with reasonable detection efficiency. The final geometry of the detector chosen by UC Berkeley and Lawrence Livermore National Laboratory was an 8-by-8 array of 0.5-cm-by- 0.5-cm-by-5-cm Bi 4Ge 3O 12 (BGO) crystals, with pixels shielded by 1-mm of lead. The purpose of my research was to model the detector response using MCNP, a Monte Carlo3 code to demonstrate its expected sensitivity and ability to generate images, under conditions that could be tested experimentally and to determine the lowest energy threshold applicable.« less

Gain Shift Corrections at Chi-Nu

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

Brown, Tristan Brooks; Devlin, Matthew James

Ambient conditions have the potential to cause changes in liquid scintillator detector gain that vary with time and temperature. These gain shifts can lead to poor resolution in both energy as well as pulse shape discrimination. In order to correct for these shifts in the Chi-Nu high energy array, a laser system has been developed for calibration of the pulse height signals.

"Stereo Compton cameras" for the 3-D localization of radioisotopes

NASA Astrophysics Data System (ADS)

Takeuchi, K.; Kataoka, J.; Nishiyama, T.; Fujita, T.; Kishimoto, A.; Ohsuka, S.; Nakamura, S.; Adachi, S.; Hirayanagi, M.; Uchiyama, T.; Ishikawa, Y.; Kato, T.

2014-11-01

The Compton camera is a viable and convenient tool used to visualize the distribution of radioactive isotopes that emit gamma rays. After the nuclear disaster in Fukushima in 2011, there is a particularly urgent need to develop "gamma cameras", which can visualize the distribution of such radioisotopes. In response, we propose a portable Compton camera, which comprises 3-D position-sensitive GAGG scintillators coupled with thin monolithic MPPC arrays. The pulse-height ratio of two MPPC-arrays allocated at both ends of the scintillator block determines the depth of interaction (DOI), which dramatically improves the position resolution of the scintillation detectors. We report on the detailed optimization of the detector design, based on Geant4 simulation. The results indicate that detection efficiency reaches up to 0.54%, or more than 10 times that of other cameras being tested in Fukushima, along with a moderate angular resolution of 8.1° (FWHM). By applying the triangular surveying method, we also propose a new concept for the stereo measurement of gamma rays by using two Compton cameras, thus enabling the 3-D positional measurement of radioactive isotopes for the first time. From one point source simulation data, we ensured that the source position and the distance to the same could be determined typically to within 2 meters' accuracy and we also confirmed that more than two sources are clearly separated by the event selection from two point sources of simulation data.

The EGRET high energy gamma ray telescope

NASA Technical Reports Server (NTRS)

Hartman, R. C.; Bertsch, D. L.; Fichtel, C. E.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.; Mayer-Hasselwander, H. A.

1992-01-01

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (GRO) is sensitive in the energy range from about 20 MeV to about 30,000 MeV. Electron-positron pair production by incident gamma photons is utilized as the detection mechanism. The pair production occurs in tantalum foils interleaved with the layers of a digital spark chamber system; the spark chamber records the tracks of the electron and positron, allowing the reconstruction of the arrival direction of the gamma ray. If there is no signal from the charged particle anticoincidence detector which surrounds the upper part of the detector, the spark chamber array is triggered by two hodoscopes of plastic scintillators. A time of flight requirement is included to reject events moving backward through the telescope. The energy of the gamma ray is primarily determined by absorption of the energies of the electron and positron in a 20 cm deep NaI(Tl) scintillator.

The EGRET high energy gamma ray telescope

NASA Astrophysics Data System (ADS)

Hartman, R. C.; Bertsch, D. L.; Fichtel, C. E.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.; Mayer-Hasselwander, H. A.; Michelson, P. F.; von Montigny, C.; Nolan, P. L.; Pinkau, K.; Rothermel, H.; Schneid, E.; Sommer, M.; Sreekumar, P.; Thompson, D. J.

1992-02-01

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (GRO) is sensitive in the energy range from about 20 MeV to about 30,000 MeV. Electron-positron pair production by incident gamma photons is utilized as the detection mechanism. The pair production occurs in tantalum foils interleaved with the layers of a digital spark chamber system; the spark chamber records the tracks of the electron and positron, allowing the reconstruction of the arrival direction of the gamma ray. If there is no signal from the charged particle anticoincidence detector which surrounds the upper part of the detector, the spark chamber array is triggered by two hodoscopes of plastic scintillators. A time of flight requirement is included to reject events moving backward through the telescope. The energy of the gamma ray is primarily determined by absorption of the energies of the electron and positron in a 20 cm deep NaI(Tl) scintillator.

Detector for measuring the π + → e +v branching fraction

DOE PAGES

Aguilar-Arevalo, A. A.; Aoki, M.; Blecher, M.; ...

2015-04-13

The PIENU experiment at TRIUMF is aimed at a measurement of the branching ratio R e/u = Γ((π + → e +v e) + (π + → e +v eγ))/Γ((π + → μ +v μ) + (π + → μ +v μγ)) with precision < 0.1%. Incident pions, delivered at the rate of 60 kHz with momentum 75 MeV/c, were degraded and stopped in a plastic scintillator target. Pions and their decay product positrons were detected with plastic scintillators and tracked with multiwire proportional chambers and silicon strip detectors. The energies of the positrons were measured in a spectrometer consistingmore » of a large NaI(Tℓ) crystal surrounded by an array of pure CsI crystals. This paper provides a description of the PIENU experimental apparatus and its performance in pursuit of R e/u« less

Fission-fragment detector for DANCE based on thin scintillating films

NASA Astrophysics Data System (ADS)

Rusev, G.; Roman, A. R.; Daum, J. K.; Springs, R. K.; Bond, E. M.; Jandel, M.; Baramsai, B.; Bredeweg, T. A.; Couture, A.; Favalli, A.; Ianakiev, K. D.; Iliev, M. L.; Mosby, S.; Ullmann, J. L.; Walker, C. L.

2015-12-01

A fission-fragment detector based on thin scintillating films has been built to serve as a trigger/veto detector in neutron-induced fission measurements at DANCE. The fissile material is surrounded by scintillating films providing 4 π detection of the fission fragments. The scintillation photons were registered with silicon photomultipliers. A measurement of the 235U (n , f) reaction with this detector at DANCE revealed a correct time-of-flight spectrum and provided an estimate for the efficiency of the prototype detector of 11.6(7)%. Design and test measurements with the detector are described.

Investigation of spatial resolution and temporal performance of SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout) with integrated electrostatic focusing

NASA Astrophysics Data System (ADS)

Scaduto, David A.; Lubinsky, Anthony R.; Rowlands, John A.; Kenmotsu, Hidenori; Nishimoto, Norihito; Nishino, Takeshi; Tanioka, Kenkichi; Zhao, Wei

2014-03-01

We have previously proposed SAPHIRE (scintillator avalanche photoconductor with high resolution emitter readout), a novel detector concept with potentially superior spatial resolution and low-dose performance compared with existing flat-panel imagers. The detector comprises a scintillator that is optically coupled to an amorphous selenium photoconductor operated with avalanche gain, known as high-gain avalanche rushing photoconductor (HARP). High resolution electron beam readout is achieved using a field emitter array (FEA). This combination of avalanche gain, allowing for very low-dose imaging, and electron emitter readout, providing high spatial resolution, offers potentially superior image quality compared with existing flat-panel imagers, with specific applications to fluoroscopy and breast imaging. Through the present collaboration, a prototype HARP sensor with integrated electrostatic focusing and nano- Spindt FEA readout technology has been fabricated. The integrated electron-optic focusing approach is more suitable for fabricating large-area detectors. We investigate the dependence of spatial resolution on sensor structure and operating conditions, and compare the performance of electrostatic focusing with previous technologies. Our results show a clear dependence of spatial resolution on electrostatic focusing potential, with performance approaching that of the previous design with external mesh-electrode. Further, temporal performance (lag) of the detector is evaluated and the results show that the integrated electrostatic focusing design exhibits comparable or better performance compared with the mesh-electrode design. This study represents the first technical evaluation and characterization of the SAPHIRE concept with integrated electrostatic focusing.

Photometric and spectroscopic gamma-ray observations of solar transient phenomena using long duration balloons

NASA Technical Reports Server (NTRS)

Pelling, M. R.; Duttweiler, F.; Lin, R. F.; Levedahl, W. K.; Primbach, H.; Curtis, D. W.; Burley, K. C.

1985-01-01

A program currently in progress to conduct extended duration spectroscopic and photometric observation of solar X-ray phenomena from balloons is described. High photometric sensitivity to weak hard X-ray bursts is attained using a 600 sq cm array of phoswich scintillators. High spectral resolution for stronger bursts is available from an array of planar germanium detectors. These instruments are carried in a novel balloon gondola dssigned for the 15 to 20 day float durations available through using conventional zero pressure balloons in the radiation controlled (RACOON) mode.

Photometric and spectroscopic gamma-ray observations of solar transient phenomena using long duration balloons

NASA Astrophysics Data System (ADS)

Pelling, M. R.; Duttweiler, F.; Lin, R. F.; Levedahl, W. K.; Primbach, H.; Curtis, D. W.; Burley, K. C.

1985-08-01

A program currently in progress to conduct extended duration spectroscopic and photometric observation of solar X-ray phenomena from balloons is described. High photometric sensitivity to weak hard X-ray bursts is attained using a 600 sq cm array of phoswich scintillators. High spectral resolution for stronger bursts is available from an array of planar germanium detectors. These instruments are carried in a novel balloon gondola dssigned for the 15 to 20 day float durations available through using conventional zero pressure balloons in the radiation controlled (RACOON) mode.

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.

Development of a novel depth of interaction PET detector using highly multiplexed G-APD cross-strip encoding

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

Kolb, A., E-mail: armin.kolb@med.uni-tuebingen.de; Parl, C.; Liu, C. C.

Purpose: The aim of this study was to develop a prototype PET detector module for a combined small animal positron emission tomography and magnetic resonance imaging (PET/MRI) system. The most important factor for small animal imaging applications is the detection sensitivity of the PET camera, which can be optimized by utilizing longer scintillation crystals. At the same time, small animal PET systems must yield a high spatial resolution. The measured object is very close to the PET detector because the bore diameter of a high field animal MR scanner is limited. When used in combination with long scintillation crystals, thesemore » small-bore PET systems generate parallax errors that ultimately lead to a decreased spatial resolution. Thus, we developed a depth of interaction (DoI) encoding PET detector module that has a uniform spatial resolution across the whole field of view (FOV), high detection sensitivity, compactness, and insensitivity to magnetic fields. Methods: The approach was based on Geiger mode avalanche photodiode (G-APD) detectors with cross-strip encoding. The number of readout channels was reduced by a factor of 36 for the chosen block elements. Two 12 × 2 G-APD strip arrays (25μm cells) were placed perpendicular on each face of a 12 × 12 lutetium oxyorthosilicate crystal block with a crystal size of 1.55 × 1.55 × 20 mm. The strip arrays were multiplexed into two channels and used to calculate the x, y coordinates for each array and the deposited energy. The DoI was measured in step sizes of 1.8 mm by a collimated {sup 18}F source. The coincident resolved time (CRT) was analyzed at all DoI positions by acquiring the waveform for each event and applying a digital leading edge discriminator. Results: All 144 crystals were well resolved in the crystal flood map. The average full width half maximum (FWHM) energy resolution of the detector was 12.8% ± 1.5% with a FWHM CRT of 1.14 ± 0.02 ns. The average FWHM DoI resolution over 12 crystals was 2.90 ± 0.15 mm. Conclusions: The novel DoI PET detector, which is based on strip G-APD arrays, yielded a DoI resolution of 2.9 mm and excellent timing and energy resolution. Its high multiplexing factor reduces the number of electronic channels. Thus, this cross-strip approach enables low-cost, high-performance PET detectors for dedicated small animal PET and PET/MRI and potentially clinical PET/MRI systems.« less

Liquid Scintillator Production for the NOvA Experiment

DOE PAGES

Mufson, S.; Baugh, B.; Bower, C.; ...

2015-04-15

The NOvA collaboration blended and delivered 8.8 kt (2.72M gal) of liquid scintillator as the active detector medium to its near and far detectors. The composition of this scintillator was specifically developed to satisfy NOvA's performance requirements. A rigorous set of quality control procedures was put in place to verify that the incoming components and the blended scintillator met these requirements. The scintillator was blended commercially in Hammond, IN. The scintillator was shipped to the NOvA detectors using dedicated stainless steel tanker trailers cleaned to food grade.

Elastic and Inelastic Scattering of Neutrons using a CLYC array

NASA Astrophysics Data System (ADS)

Brown, Tristan; Doucet, E.; Chowdhury, P.; Lister, C. J.; Wilson, G. L.; Devlin, M.; Mosby, S.

2015-10-01

CLYC scintillators, which have dual neutron and gamma response, have recently ushered in the possibility of fast neutron spectroscopy without time-of-flight (TOF). A 16-element array of 1'' x 1'' 6Li-depleted CLYC crystals, where pulse-shape-discrimination is achieved via digital pulse processing, has been commissioned at UMass Lowell. In an experiment at LANSCE, high energy neutrons were used to bombard 56Fe and 238U targets, in order to measure elastic and inelastic neutron scattering cross sections as a function of energy and angle with the array. The array is placed very close to the targets for enhanced geometrical solid angles for scattered neutrons compared to standard neutron-TOF measurements. A pulse-height spectrum of scattered neutrons in the detectors is compared to the energy of the incident neutrons, which is measured via the TOF of the pulsed neutrons from the source to the detectors. Recoil corrections are necessary to combine the energy spectra from all the detectors to obtain angle-integrated elastic and inelastic cross-sections. The detection techniques, analysis procedures and results will be presented. Supported by NNSA-SSAA program through DOE Grant DE-NA00013008.

A design of a PET detector using micro-channel plate photomultipliers with transmission-line readout

NASA Astrophysics Data System (ADS)

Kim, H.; Frisch, H.; Chen, C.-T.; Genat, J.-F.; Tang, F.; Moses, W. W.; Choong, W. S.; Kao, C.-M.

2010-10-01

A computer simulation study has been conducted to investigate the feasibility of a positron emission tomography (PET) detector design by using micro-channel plate (MCP) photomultiplier tubes (PMT) with transmission-line (TL) readout and waveform sampling. The detector unit consisted of a 24×24 array of pixelated LSO crystals, each of which was 4×4×25 mm 3 in size, and two 102×102 mm 2 MCP-PMTs coupled to both sides of the scintillator array. The crystal (and TL) pitch was 4.25 mm and reflective medium was inserted between the crystals. The transport of the optical photons inside the scintillator were simulated by using the Geant4 package. The output pulses of the MCP-PMT/TL unit were formed by applying the measured single photo-electron response of the MCP-PMT/TL unit to each individual photon that interacts with the photo-cathode of the MCP-PMT. The waveforms of the pulses at both ends of the TL strips were measured and analyzed to produce energy and timing information for the detected event. An experimental setup was developed by employing a Photonis Planacon MCP-PMT (XP85022) and a prototype TL board for measuring the single photo-electron response of the MCP-PMT/TL. The simulation was validated by comparing the predicted output pulses to measurements obtained with a single MCP-PMT/TL coupled to an LSO crystal exposed to 511 keV gamma rays. The validated simulation was then used to investigate the performance of the proposed new detector design. Our simulation result indicates an energy resolution of ˜11% at 511 keV. When using a 400-600 keV energy window, we obtain a coincidence timing resolution of ˜323 ps FWHM and a coincidence detection efficiency of ˜40% for normally incident 511 keV photons. For the positioning accuracy, it is determined by the pitch of the TLs (and crystals) in the direction normal to the TLs and measured to be ˜2.5 mm in the direction parallel to the TLs. The energy and timing obtained at the front- and back-end of the scintillator array also show differences that are correlated with the depth of interaction of the event.

A Design of a PET Detector Using Micro-Channel Plate Photomultipliers with Transmission-Line Readout.

PubMed

Kim, H; Frisch, H; Chen, C-T; Genat, J-F; Tang, F; Moses, W W; Choong, W S; Kao, C-M

2010-01-01

A computer simulation study has been conducted to investigate the feasibility of a positron emission tomography (PET) detector design by using micro-channel plate (MCP) photomultiplier tubes (PMT) with transmission-line (TL) read-out and waveform sampling. The detector unit consisted of a 24×24 array of pixelated LSO crystals, each of which was 4×4×25 mm(3) in size, and two 102×102 mm(2) MCP-PMTs coupled to both sides of the scintillator array. The crystal (and TL) pitch was 4.25 mm and reflective medium was inserted between the crystals. The transport of the optical photons inside the scintillator were simulated by using the Geant4 package. The output pulses of the MCP-PMT/TL unit were formed by applying the measured single photo-electron response of the MCP-PMT/TL unit to each individual photon that interacts with the photo-cathode of the MCP-PMT. The waveforms of the pulses at both ends of the TL strips were measured and analyzed to produce energy and timing information for the detected event. An experimental setup was developed by employing a Photonis Planacon MCP-PMT (XP85022) and a prototype TL board for measuring the single photo-electron response of the MCP-PMT/TL. The simulation was validated by comparing the predicted output pulses to measurements obtained with a single MCP-PMT/TL coupled to an LSO crystal exposed to 511 keV gamma rays. The validated simulation was then used to investigate the performance of the proposed new detector design. Our simulation result indicates an energy resolution of ~11% at 511 keV. When using a 400-600 keV energy window, we obtain a coincidence timing resolution of ~323 ps FWHM and a coincidence detection efficiency of ~40% for normally-incident 511keV photons. For the positioning accuracy, it is determined by the pitch of the TLs (and crystals) in the direction normal to the TLs and measured to be ~2.5 mm in the direction parallel to the TLs. The energy and timing obtained at the front- and back-end of the scintillator array also show differences that are correlated with the depth of interaction of the event.

Energy calibration of organic scintillation detectors for. gamma. rays

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

Gu Jiahui; Xiao Genlai; Liu Jingyi

1988-10-01

An experimental method of calibrating organic detectors is described. A NaI(T1) detector has some advantages of high detection efficiency, good energy resolution, and definite position of the back-scattering peak. The precise position of the Compton edge can be determined by coincidence measurement between the pulse of an organic scintillation detector and the pulse of the back-scattering peak from NaI(T1) detector. It can be used to calibrate various sizes and shapes of organic scintillation detectors simply and reliably. The home-made plastic and organic liquid scintillation detectors are calibrated and positions of the Compton edge as a function of ..gamma..-ray energies aremore » obtained.« less

Correlated fission data measurements with DANCE and NEUANCE

NASA Astrophysics Data System (ADS)

Jandel, M.; Baramsai, B.; Bredeweg, T. A.; Couture, A.; Favalli, A.; Hayes, A. C.; Ianakiev, K. D.; Iliev, M. L.; Kawano, T.; Mosby, S.; Rusev, G.; Stetcu, I.; Talou, P.; Ullmann, J. L.; Vieira, D. J.; Walker, C. L.; Wilhelmy, J. B.

2018-02-01

To enhance the capabilities of the DANCE array, a new detector array NEUANCE was developed to enable simultaneous measurements of prompt fission neutrons and γ rays. NEUANCE was designed and constructed using 21 stilbene organic scintillator crystals. It was installed in the central cavity of the DANCE array. Signals from the 160 BaF2 detectors of DANCE and the 21 detectors of NEUANCE were merged into a newly designed high-density high-throughput data acquisition system. The excellent pulse shape discrimination properties of stilbene enabled detection of neutrons with energy thresholds as low as 30-40 keVee. A fission reaction tagging method was developed using a NEUANCE γ-ray or neutron signal. The probability of detecting a neutron from the spontaneous fission of 252Cf using NEUANCE is ∼47%. New correlated data for prompt fission neutrons and prompt fission γ rays were obtained for 252Cf using this high detection efficiency experimental setup. Average properties of prompt fission neutron emission as a function of prompt fission γ-ray quantities were also obtained, suggesting that neutron and γ-ray emission in fission are correlated.

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

Jandel, Marian; Baramsai, Baramsai; Bredeweg, Todd Allen

To enhance the capabilities of the DANCE array, a new detector array NEUANCE was developed to enable simultaneous measurements of prompt fission neutrons and γ rays. NEUANCE was designed and constructed using 21 stilbene organic scintillator crystals. It was installed in the central cavity of the DANCE array. Signals from the 160 BaF 2 detectors of DANCE and the 21 detectors of NEUANCE were merged into a newly designed high-density high-throughput data acquisition system. The excellent pulse shape discrimination properties of stilbene enabled detection of neutrons with energy thresholds as low as 30–40 keVee. A fission reaction tagging method wasmore » developed using a NEUANCE γ-ray or neutron signal. The probability of detecting a neutron from the spontaneous fission of 252Cf using NEUANCE is 47%. New correlated data for prompt fission neutrons and prompt fission rays were obtained for 252Cf using this high detection efficiency experimental setup. In conclusion, average properties of prompt fission neutron emission as a function of prompt fission γ-ray quantities were also obtained, suggesting that neutron and γ-ray emission in fission are correlated.« less

Photon statistics in scintillation crystals

NASA Astrophysics Data System (ADS)

Bora, Vaibhav Joga Singh

Scintillation based gamma-ray detectors are widely used in medical imaging, high-energy physics, astronomy and national security. Scintillation gamma-ray detectors are eld-tested, relatively inexpensive, and have good detection eciency. Semi-conductor detectors are gaining popularity because of their superior capability to resolve gamma-ray energies. However, they are relatively hard to manufacture and therefore, at this time, not available in as large formats and much more expensive than scintillation gamma-ray detectors. Scintillation gamma-ray detectors consist of: a scintillator, a material that emits optical (scintillation) photons when it interacts with ionization radiation, and an optical detector that detects the emitted scintillation photons and converts them into an electrical signal. Compared to semiconductor gamma-ray detectors, scintillation gamma-ray detectors have relatively poor capability to resolve gamma-ray energies. This is in large part attributed to the "statistical limit" on the number of scintillation photons. The origin of this statistical limit is the assumption that scintillation photons are either Poisson distributed or super-Poisson distributed. This statistical limit is often dened by the Fano factor. The Fano factor of an integer-valued random process is dened as the ratio of its variance to its mean. Therefore, a Poisson process has a Fano factor of one. The classical theory of light limits the Fano factor of the number of photons to a value greater than or equal to one (Poisson case). However, the quantum theory of light allows for Fano factors to be less than one. We used two methods to look at the correlations between two detectors looking at same scintillation pulse to estimate the Fano factor of the scintillation photons. The relationship between the Fano factor and the correlation between the integral of the two signals detected was analytically derived, and the Fano factor was estimated using the measurements for SrI2:Eu, YAP:Ce and CsI:Na. We also found an empirical relationship between the Fano factor and the covariance as a function of time between two detectors looking at the same scintillation pulse. This empirical model was used to estimate the Fano factor of LaBr3:Ce and YAP:Ce using the experimentally measured timing-covariance. The estimates of the Fano factor from the time-covariance results were consistent with the estimates of the correlation between the integral signals. We found scintillation light from some scintillators to be sub-Poisson. For the same mean number of total scintillation photons, sub-Poisson light has lower noise. We then conducted a simulation study to investigate whether this low-noise sub-Poisson light can be used to improve spatial resolution. We calculated the Cramer-Rao bound for dierent detector geometries, position of interactions and Fano factors. The Cramer-Rao calculations were veried by generating simulated data and estimating the variance of the maximum likelihood estimator. We found that the Fano factor has no impact on the spatial resolution in gamma-ray imaging systems.

Influence of depth of interaction upon the performance of scintillator detectors.

PubMed

Brown, Mark S; Gundacker, Stefan; Taylor, Alaric; Tummeltshammer, Clemens; Auffray, Etiennette; Lecoq, Paul; Papakonstantinou, Ioannis

2014-01-01

The uncertainty in time of particle detection within a scintillator detector, characterised by the coincidence time resolution (CTR), is explored with respect to the interaction position within the scintillator crystal itself. Electronic collimation between two scintillator detectors is utilised to determine the CTR with depth of interaction (DOI) for different materials, geometries and wrappings. Significantly, no relationship between the CTR and DOI is observed within experimental error. Confinement of the interaction position is seen to degrade the CTR in long scintillator crystals by 10%.

Preclinical positron emission tomography scanner based on a monolithic annulus of scintillator: initial design study

PubMed Central

Stolin, Alexander V.; Martone, Peter F.; Jaliparthi, Gangadhar; Raylman, Raymond R.

2017-01-01

Abstract. Positron emission tomography (PET) scanners designed for imaging of small animals have transformed translational research by reducing the necessity to invasively monitor physiology and disease progression. Virtually all of these scanners are based on the use of pixelated detector modules arranged in rings. This design, while generally successful, has some limitations. Specifically, use of discrete detector modules to construct PET scanners reduces detection sensitivity and can introduce artifacts in reconstructed images, requiring the use of correction methods. To address these challenges, and facilitate measurement of photon depth-of-interaction in the detector, we investigated a small animal PET scanner (called AnnPET) based on a monolithic annulus of scintillator. The scanner was created by placing 12 flat facets around the outer surface of the scintillator to accommodate placement of silicon photomultiplier arrays. Its performance characteristics were explored using Monte Carlo simulations and sections of the NEMA NU4-2008 protocol. Results from this study revealed that AnnPET’s reconstructed spatial resolution is predicted to be ∼1  mm full width at half maximum in the radial, tangential, and axial directions. Peak detection sensitivity is predicted to be 10.1%. Images of simulated phantoms (mini-hot rod and mouse whole body) yielded promising results, indicating the potential of this system for enhancing PET imaging of small animals. PMID:28097210

A SPECT system simulator built on the SolidWorks TM 3D-Design package.

PubMed

Li, Xin; Furenlid, Lars R

2014-08-17

We have developed a GPU-accelerated SPECT system simulator that integrates into instrument-design workflow [1]. This simulator includes a gamma-ray tracing module that can rapidly propagate gamma-ray photons through arbitrary apertures modeled by SolidWorks TM -created stereolithography (.STL) representations with a full complement of physics cross sections [2, 3]. This software also contains a scintillation detector simulation module that can model a scintillation detector with arbitrary scintillation crystal shape and light-sensor arrangement. The gamma-ray tracing module enables us to efficiently model aperture and detector crystals in SolidWorks TM and save them as STL file format, then load the STL-format model into this module to generate list-mode results of interacted gamma-ray photon information (interaction positions and energies) inside the detector crystals. The Monte-Carlo scintillation detector simulation module enables us to simulate how scintillation photons get reflected, refracted and absorbed inside a scintillation detector, which contributes to more accurate simulation of a SPECT system.

A SPECT system simulator built on the SolidWorksTM 3D design package

NASA Astrophysics Data System (ADS)

Li, Xin; Furenlid, Lars R.

2014-09-01

We have developed a GPU-accelerated SPECT system simulator that integrates into instrument-design work flow [1]. This simulator includes a gamma-ray tracing module that can rapidly propagate gamma-ray photons through arbitrary apertures modeled by SolidWorksTM-created stereolithography (.STL) representations with a full com- plement of physics cross sections [2, 3]. This software also contains a scintillation detector simulation module that can model a scintillation detector with arbitrary scintillation crystal shape and light-sensor arrangement. The gamma-ray tracing module enables us to efficiently model aperture and detector crystals in SolidWorksTM and save them as STL file format, then load the STL-format model into this module to generate list-mode results of interacted gamma-ray photon information (interaction positions and energies) inside the detector crystals. The Monte-Carlo scintillation detector simulation module enables us to simulate how scintillation photons get reflected, refracted and absorbed inside a scintillation detector, which contributes to more accurate simulation of a SPECT system.

Inorganic scintillating materials and scintillation detectors

PubMed Central

YANAGIDA, Takayuki

2018-01-01

Scintillation materials and detectors that are used in many applications, such as medical imaging, security, oil-logging, high energy physics and non-destructive inspection, are reviewed. The fundamental physics understood today is explained, and common scintillators and scintillation detectors are introduced. The properties explained here are light yield, energy non-proportionality, emission wavelength, energy resolution, decay time, effective atomic number and timing resolution. For further understanding, the emission mechanisms of scintillator materials are also introduced. Furthermore, unresolved problems in scintillation phenomenon are considered, and my recent interpretations are discussed. These topics include positive hysteresis, the co-doping of non-luminescent ions, the introduction of an aimed impurity phase, the excitation density effect and the complementary relationship between scintillators and storage phosphors. PMID:29434081

MO-G-17A-01: Innovative High-Performance PET Imaging System for Preclinical Imaging and Translational Researches

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

Sun, X; Lou, K; Rice University, Houston, TX

Purpose: To develop a practical and compact preclinical PET with innovative technologies for substantially improved imaging performance required for the advanced imaging applications. Methods: Several key components of detector, readout electronics and data acquisition have been developed and evaluated for achieving leapfrogged imaging performance over a prototype animal PET we had developed. The new detector module consists of an 8×8 array of 1.5×1.5×30 mm{sup 3} LYSO scintillators with each end coupled to a latest 4×4 array of 3×3 mm{sup 2} Silicon Photomultipliers (with ∼0.2 mm insensitive gap between pixels) through a 2.0 mm thick transparent light spreader. Scintillator surface andmore » reflector/coupling were designed and fabricated to reserve air-gap to achieve higher depth-of-interaction (DOI) resolution and other detector performance. Front-end readout electronics with upgraded 16-ch ASIC was newly developed and tested, so as the compact and high density FPGA based data acquisition and transfer system targeting 10M/s coincidence counting rate with low power consumption. The new detector module performance of energy, timing and DOI resolutions with the data acquisition system were evaluated. Initial Na-22 point source image was acquired with 2 rotating detectors to assess the system imaging capability. Results: No insensitive gaps at the detector edge and thus it is capable for tiling to a large-scale detector panel. All 64 crystals inside the detector were clearly separated from a flood-source image. Measured energy, timing, and DOI resolutions are around 17%, 2.7 ns and 1.96 mm (mean value). Point source image is acquired successfully without detector/electronics calibration and data correction. Conclusion: Newly developed advanced detector and readout electronics will be enable achieving targeted scalable and compact PET system in stationary configuration with >15% sensitivity, ∼1.3 mm uniform imaging resolution, and fast acquisition counting rate capability for substantially improved imaging and quantification performance for small animal imaging and image-guided radiotherapy applications. This work was supported by a research award RP120326 from Cancer Prevention and Research Institute of Texas.« less

Hodoscope readout system

DOEpatents

Lee, L.Y.

1973-12-01

A readout system has been provided for reading out a radiation multidetector device with a reduced number of signal sensors. A radiation hodoscope, such as an array of scintillation counters, multiwire proportional counter array, or a set of multidetectors which do not receive signals simultaneously, is divided into equal numbered groups. A first group of signal terminals is connected to the equal numbered groups of detectors so that a signal from any one of the detectors of a group will be fed to one of the first group of terminals. A second group of signal terminals is connected to the detector groups so that a signal from a particular numbered detector of each of the detector groups is connected to one of the second group of terminals. Both groups of signal terminals are, in turn, coupled to signal sensors so that when a signal is simultaneously observed in one of the first group of terminals and one of the second group of tenniinals the specific detector detecting a radiation event is determined. The sensors are arranged in such a manner that a binary code is developed from their outputs which can be stored in a digital storage means according to the location of the event in the multidetector device. (Official Gazette)

A neutron Albedo system with time rejection for landmine and IED detection

NASA Astrophysics Data System (ADS)

Kovaltchouk, V. D.; Andrews, H. R.; Clifford, E. T. H.; Faust, A. A.; Ing, H.; McFee, J. E.

2011-10-01

A neutron Albedo system has been developed for imaging of buried landmines and improvised explosive devices (IEDs). It involves irradiating the ground with fast neutrons and subsequently detecting the thermalized neutrons that return. A scintillating 6Li loaded ZnS(Ag) screen with a sensitive area of 40 cm×40 cm is used as a thermal neutron detector. Scintillation light is captured by orthogonal arrays of wavelength-shifting fibers placed on either side of the scintillator surface and then transferred to X and Y multi-pixel PMTs. A timing circuit, used with pulsed neutron sources, records the time when a neutron detection takes place relative to an external synchronization pulse from the pulsed source. Experimental tests of the Albedo system performance have been done in a sand box with a 252Cf neutron source (no time gating) and with pulsed D-D (2.6 MeV) neutrons from the Defense R&D Ottawa Van de Graaff accelerator (with time gating). Information contained in the time evolution of the thermal neutron field provided improved detection capability and image reconstruction. The detector design is described and experimental results are discussed.

Detectors for Active Interrogation Applications

NASA Astrophysics Data System (ADS)

Clarke, S. D.; Hamel, M. C.; Bourne, M. M.; Pozzi, S. A.

Active interrogation creates an environment that is particularly challenging from a radiation-detection standpoint: the elevated background levels from the source can mask the desired signatures from the SNM. Neutron based interrogation experiments have shown that nanosecond-level timing is required to discriminate induced-fission neutrons from the scattered source neutrons. Previous experiments using high-energy bremsstrahlung X-rays have demonstrated the ability to induce and detect prompt photofission neutrons from single target materials; however, a real-world application would require spectroscopic capability to discern between photofission neutrons emitted by SNM and neutrons emitted by other reactions in non-SNM. Using digital pulse-shape discrimination, organic liquid scintillators are capable of reliably detecting neutrons in an intense gamma-ray field. Photon misclassification rates as low as 1 in 106 have been achieved, which is approaching the level of gaseous neutron detectors such as 3He without the need for neutron moderation. These scintillators also possess nanosecond-timing resolution, making them candidates for both neutron-and photon-driven active interrogation systems. We have applied an array of liquid and NaI(Tl) scintillators to successfully image 13.7 kg of HEU interrogated by a DT neutron generator; the system was in the direct presence of the accelerator during the experiment.

Liquid scintillator composition optimization for use in ultra-high energy cosmic ray detector systems

NASA Astrophysics Data System (ADS)

Beznosko, Dmitriy; Batyrkhanov, Ayan; Iakovlev, Alexander; Yelshibekov, Khalykbek

2017-06-01

The Horizon-T (HT) detector system and the currently under R&D HT-KZ detector system are designed for the detection of Extensive Air Showers (EAS) with energies above ˜1016 eV (˜1017 eV for HT-KZ). The main challenges in both detector systems are the fast time resolutions needed for studying the temporary structure of EAS, and the extremely wide dynamic range needed to study the spatial distribution of charged particles in EAS disks. In order to detect the low-density of charged particles far from the EAS axis, a large-area detector is needed. Liquid scintillator with low cost would be a possible solution for such a detector, including the recently developed safe and low-cost water-based liquid scintillators. Liquid organic scintillators give a fast and high light yield (LY) for charged particle detection. It is similar to plastic scintillator in properties but is cost effective for large volumes. With liquid scintillator, one can create detection volumes that are symmetric and yet retain high LY detection. Different wavelength shifters affect the scintillation light by changing the output spectrum into the best detection region. Results of the latest studies of the components optimization in the liquid scintillator formulae are presented.

Neutron detector using lithiated glass-scintillating particle composite

DOEpatents

Wallace, Steven [Knoxville, TN; Stephan, Andrew C [Knoxville, TX; Dai, Sheng [Knoxville, TN; Im, Hee-Jung [Knoxville, TN

2009-09-01

A neutron detector composed of a matrix of scintillating particles imbedded in a lithiated glass is disclosed. The neutron detector detects the neutrons by absorbing the neutron in the lithium-6 isotope which has been enriched from the natural isotopic ratio to a commercial ninety five percent. The utility of the detector is optimized by suitably selecting scintillating particle sizes in the range of the alpha and the triton. Nominal particle sizes are in the range of five to twenty five microns depending upon the specific scintillating particle selected.

TA×4

NASA Astrophysics Data System (ADS)

Sagawa, Hiroyuki

How cosmic rays obtain energies of about 1020 eV and where they come from are big mysteries in physics. The Telescope Array (TA) is comprised of Surface Detectors (SDs) and Fluorescence Detectors (FDs) located in Utah, U.S.A., and aims to explore the origin of highest-energy cosmic rays. The SD array consists of 507 scintillation detectors arranged on a square grid of 1.2-km spacing, covering approximately 700 km2. The FD telescopes, located at three sites, look over the surface array. Using the first five years of data collected by the surface detectors, we found a cluster of cosmic rays with energies greater than 5.7 × 1019 eV that we call the hot spot. With enhanced statistics, we expect to observe the structure of that hot spot along with other possible excesses, and point sources along with the correlations with extreme phenomena in the nearby universe. We plan to make the area of the TA SD array four times larger to approximately 3,000 km2, by adding 500 SDs on a square grid of 2.08-km spacing. Two FD stations will be built viewing the new SD array. This TA extension that we call TA×4 will greatly accelerate the speed at which we will reach the goals mentioned above, and will enhance cosmic-ray energy spectrum measurement and composition study at the highest energies by TA. At this conference, we present our plan for TA×4.

Investigation of OPET Performance Using GATE, a Geant4-Based Simulation Software.

PubMed

Rannou, Fernando R; Kohli, Vandana; Prout, David L; Chatziioannou, Arion F

2004-10-01

A combined optical positron emission tomography (OPET) system is capable of both optical and PET imaging in the same setting, and it can provide information/interpretation not possible in single-mode imaging. The scintillator array here serves the dual function of coupling the optical signal from bioluminescence/fluorescence to the photodetector and also of channeling optical scintillations from the gamma rays. We report simulation results of the PET part of OPET using GATE, a Geant4 simulation package. The purpose of this investigation is the definition of the geometric parameters of the OPET tomograph. OPET is composed of six detector blocks arranged in a hexagonal ring-shaped pattern with an inner radius of 15.6 mm. Each detector consists of a two-dimensional array of 8 × 8 scintillator crystals each measuring 2 × 2 × 10 mm(3). Monte Carlo simulations were performed using the GATE software to measure absolute sensitivity, depth of interaction, and spatial resolution for two ring configurations, with and without gantry rotations, two crystal materials, and several crystal lengths. Images were reconstructed with filtered backprojection after angular interleaving and transverse one-dimensional interpolation of the sinogram. We report absolute sensitivities nearly seven times that of the prototype microPET at the center of field of view and 2.0 mm tangential and 2.3 mm radial resolutions with gantry rotations up to an 8.0 mm radial offset. These performance parameters indicate that the imaging spatial resolution and sensitivity of the OPET system will be suitable for high-resolution and high-sensitivity small-animal PET imaging.

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

PubMed

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

2017-02-13

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

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

NASA Astrophysics Data System (ADS)

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

2017-03-01

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

Influence of Depth of Interaction upon the Performance of Scintillator Detectors

PubMed Central

Brown, Mark S.; Gundacker, Stefan; Taylor, Alaric; Tummeltshammer, Clemens; Auffray, Etiennette; Lecoq, Paul; Papakonstantinou, Ioannis

2014-01-01

The uncertainty in time of particle detection within a scintillator detector, characterised by the coinci- dence time resolution (CTR), is explored with respect to the interaction position within the scintillator crystal itself. Electronic collimation between two scintillator detectors is utilised to determine the CTR with depth of interaction (DOI) for different materials, geometries and wrappings. Significantly, no rela- tionship between the CTR and DOI is observed within experimental error. Confinement of the interaction position is seen to degrade the CTR in long scintillator crystals by 10%. PMID:24875832

Estimation of position resolution for DOI-PET detector using diameter 0.2 mm WLS fibers [ANIMMA--2015-IO-x5

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

Kaneko, Naomi; Ito, H.; Han, S.

We have been developing a submillimeter resolution and low-cost DOI-PET detector using wavelength shifting fibers (WLSF), scintillating crystal plates and MPPCs (Hamamatsu Photonics). Conventional design of DOI-PET detectors had approximately mm{sup 3} of resolution by using some scintillating blocks with a volume of 1 mm{sup 3}, which detects gamma-ray. They are expensive due to difficulties in processing scintillating crystals and a large number of photo-detectors, and these technologies are likely to reach the limit of the resolution. Development of a lower cost DOI-PET detector with higher resolution is challenging to popularize the PET diagnosis. We propose two type of PETmore » detector. One is a whole body PET system, and the other is a PET system for brain or small animals. Each PET system consists 6 blocks. The former consists of 6 layers of crystal plates with 300 mm x 300 mm x 4 mm. The latter consists of 16 crystal layers, forming 4 x 4 crystal arrays. The size of the crystal plate is 40 mm x 40 mm x 1 mm. Wavelength shifting fiber (WLSF) sheets are attached to above and up and down side of crystal planes. The whole PET system has 8 MPPCs attached on each side. For the brain PET detector, 9 WLSF fibers are attached on the each side. The expected position resolution would be less than 1 mm at the former system. We have performed an experimental performance estimation for the system component using {sup 22}Na radioactive source. We achieved a collection efficiency of 10% using the WLSF sheet and Ce:Gd{sub 3}(Al,Ga){sub 5}O{sub 12} (GAGG) crystals at 511 keV. The linear relationship between reconstruction position and incident position was obtained, and a resolution of 0.7 mm (FWHM) for x-axis of DOI by the WLSF readout was achieved. (authors)« less

The Use of Fast Neutron Detection for Materials Accountability

NASA Astrophysics Data System (ADS)

Nakae, L. F.; Chapline, G. F.; Glenn, A. M.; Kerr, P. L.; Kim, K. S.; Ouedraogo, S. A.; Prasad, M. K.; Sheets, S. A.; Snyderman, N. J.; Verbeke, J. M.; Wurtz, R. E.

2014-02-01

For many years at LLNL, we have been developing time-correlated neutron detection techniques and algorithms for applications such as Arms Control, Threat Detection and Nuclear Material Assay. Many of our techniques have been developed specifically for the relatively low efficiency (a few percent) inherent in man-portable systems. Historically, thermal neutron detectors (mainly 3He) were used, taking advantage of the high thermal neutron interaction cross-sections, but more recently we have been investigating the use of fast neutron detection with liquid scintillators, inorganic crystals, and in the near future, pulse-shape discriminating plastics that respond over 1000 times faster (nanoseconds versus tens of microseconds) than thermal neutron detectors. Fast neutron detection offers considerable advantages, since the inherent nanosecond production timescales of fission and neutron-induced fission are preserved and measured instead of being lost in the thermalization of thermal neutron detectors. We are now applying fast neutron technology to the safeguards regime in the form of high efficiency counters. Faster detector response times and sensitivity to neutron momentum show promise in measuring, differentiating, and assaying samples that have modest to very high count rates, as well as mixed neutron sources (e.g., Pu oxide or Mixed Cm and Pu). Here we report on measured results with our existing liquid scintillator array and promote the design of a nuclear material assay system that incorporates fast neutron detection, including the surprising result that fast liquid scintillator becomes competitive and even surpasses the precision of 3He counters measuring correlated pairs in modest (kg) samples of plutonium.

The (n,γ) campaigns at EXILL

NASA Astrophysics Data System (ADS)

Jolie, J.; Régis, J.-M.; Wilmsen, D.; Ahmed, S.; Pfeiffer, M.; Saed-Samii, N.; Warr, N.; Blanc, A.; Jentschel, M.; Köster, U.; Mutti, P.; Soldner, T.; Simpson, G.; De France, G.; Urban, W.; Drouet, F.; Vancraeyenest, A.; Baczyk, P.; Czerwinski, M.; Korgul, A.; Mazzocchi, C.; Rzaca-Urban, T.; Bruce, A.; Roberts, O. J.; Fraile, L. M.; Mach, H.; Paziy, V.; Ignatov, A.; Ilieva, S.; Kröll, Th.; Scheck, M.; Thürauf, M.; Ivanova, D.; Kisyov, S.; Lalkovski, S.; Podolyák, Zs.; Regan, P. H.; Korten, W.; Zielinska, M.; Salsac, M. D.; Habs, D.; Thirolf, P. G.; Ur, C. A.; Bernards, C.; Casten, R. F.; Cooper, N.; Werner, V.; Cakirli, R. B.; Leoni, S.; Benzoni, G.; Bocchi, G.; Bottoni, S.; Crespi, F. C. L.; Fornal, B.; Cieplicka, N.; Szpak, B.; Petrache, C. M.; Leguillon, R.; John, R.; Lorenz, C.; Massarczyk, R.; Schwengner, R.; Curien, D.; Lozeva, R.; Sengele, L.; Marginean, N.; Lica, R.

2015-05-01

At the PF1B cold neutron beam line at the Institut Laue Langevin, the EXILL array consisting of EXOGAM, GASP and ILL-Clover detectors was used to perform (n,γ) measurements at very high coincidence rates. About ten different reactions were measured in autumn 2012 using a highly collimated cold neutron beam. In spring 2013, the EXOGAM array was combined with 16 LaBr3(Ce) scintillators in the EXILL&FATIMA campaign for the measurement of lifetimes using the generalised centroid difference method. We report on the properties of the set-ups and present first results from both campaigns.

Phase II Upgrade of the GERDA Experiment for the Search of Neutrinoless Double Beta Decay

NASA Astrophysics Data System (ADS)

Majorovits, B.

Observation of neutrinoless double beta decay could answer the question regarding the Majorana or Dirac nature of neutrinos. The GERDA experiment utilizes HPGe detectors enriched with the isotope 76Ge to search for this process. Recently the GERDA collaboration has unblinded data of Phase I of the experiment. In order to further improve the sensitivity of the experiment, additionally to the coaxial detectors used, 30 BEGe detectors made from germanium enriched in 76Ge will be deployed in GERDA Phase II. BEGe detectors have superior PSD capability, thus the background can be further reduced. The liquid argon surrounding the detector array will be instrumented in order to reject background by detecting scintillation light induced in the liquid argon by radiation. After a short introduction the hardware preparations for GERDA Phase II as well as the processing and characterization of the 30 BEGe detectors are discussed.

The Pierre Auger Observatory Upgrade - Preliminary Design Report

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

Aab, Alexander

The Pierre Auger Observatory has begun a major Upgrade of its already impressive capabilities, with an emphasis on improved mass composition determination using the surface detectors of the Observatory. Known as AugerPrime, the upgrade will include new 4 m 2 plastic scintillator detectors on top of all 1660 water-Cherenkov detectors, updated and more flexible surface detector electronics, a large array of buried muon detectors, and an extended duty cycle for operations of the fluorescence detectors. This Preliminary Design Report was produced by the Collaboration in April 2015 as an internal document and information for funding agencies. It outlines the scientificmore » and technical case for AugerPrime. We now release it to the public via the arXiv server. We invite you to review the large number of fundamental results already achieved by the Observatory and our plans for the future.« less

Low momentum recoil detectors in CLAS12 at Jefferson Lab

NASA Astrophysics Data System (ADS)

Charles, Gabriel; CLAS Collaboration Collaboration

2017-01-01

Part of the experimental program in Hall B of the Jefferson Lab is dedicated to studying nucleon structure using DIS on nuclei and detecting low-momentum recoil particles in coincidence with the scattered electron. For this purpose, specially designed central detectors are required in place of the inner tracker of CLAS12 to detect particles with momenta below 100 MeV/c. We will present the status of the BONuS12 RTPC detector that will take data within the next 2 years. We will detail the main improvements made from the previous BONuS RTPC. In a second part, we will discuss another recoil experiment, called ALERT, that has been proposed to run in Hall B. The constraints being different, the recoil detector is based on a drift chamber and an array of scintillators. We will present the main differences between the two detectors and summarize the R&D performed to develop the ALERT detector.

Development of real-time thermal neutron monitor using boron-loaded plastic scintillator with optical fiber for boron neutron capture therapy.

PubMed

Ishikawa, M; Ono, K; Sakurai, Y; Unesaki, H; Uritani, A; Bengua, G; Kobayashi, T; Tanaka, K; Kosako, T

2004-11-01

A new thermal neutron monitor for boron neutron capture therapy was developed in this study. We called this monitor equipped boron-loaded plastic scintillator that uses optical fiber for signal transmission as an [scintillator with optical fiber] SOF detector. A water phantom experiment was performed to verify how the SOF detector compared with conventional method of measuring thermal neutron fluence. Measurements with a single SOF detector yielded indistinguishable signals for thermal neutrons and gamma rays. To account for the gamma ray contribution in the signal recorded by the SOF detector, a paired SOF detector system was employed. This was composed of an SOF detector with boron-loaded scintillator and an SOF detector with a boron-free scintillator. The difference between the recorded counts of these paired SOF detectors was used as the measure of the gamma ray contribution in the measured neutron fluence. The paired SOF detectors were ascertained to be effective in measuring thermal neutron flux in the range above 10(6)(n/cm(2)/s). Clinical trials using paired SOF to measure thermal neutron flux during therapy confirmed that paired SOF detectors were effective as a real-time thermal neutron flux monitor.

High-efficiency scintillation detector for combined detection of thermal and fast neutrons and gamma radiation

DOEpatents

Chiles, M.M.; Mihalczo, J.T.; Blakeman, E.D.

1987-02-27

A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation event count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

High-efficiency scintillation detector for combined of thermal and fast neutrons and gamma radiation

DOEpatents

Chiles, Marion M.; Mihalczo, John T.; Blakeman, Edward D.

1989-02-07

A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation even count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

High-efficiency scintillation detector for combined of thermal and fast neutrons and gamma radiation

DOEpatents

Chiles, Marion M.; Mihalczo, John T.; Blakeman, Edward D.

1989-01-01

A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation even count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

Hard X-ray astrophysics

NASA Technical Reports Server (NTRS)

Rothschild, R. E.

1981-01-01

Past hard X-ray and lower energy satellite instruments are reviewed and it is shown that observation above 20 keV and up to hundreds of keV can provide much valuable information on the astrophysics of cosmic sources. To calculate possible sensitivities of future arrays, the efficiencies of a one-atmosphere inch gas counter (the HEAO-1 A-2 xenon filled HED3) and a 3 mm phoswich scintillator (the HEAO-1 A-4 Na1 LED1) were compared. Above 15 keV, the scintillator was more efficient. In a similar comparison, the sensitivity of germanium detectors did not differ much from that of the scintillators, except at high energies where the sensitivity would remain flat and not rise with loss of efficiency. Questions to be addressed concerning the physics of active galaxies and the diffuse radiation background, black holes, radio pulsars, X-ray pulsars, and galactic clusters are examined.

Results from the CACTI experiment: Air-Cerenkov and particle measurements of PeV air showers at Los Alamos

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

Paling, S.; Hillas, A.M.; Berley, D.

1997-07-01

An array of six wide angle Cerenkov detectors was constructed amongst the scintillator and muon detectors of the CYGNUS II array at Los Alamos National Laboratory to investigate cosmic ray composition in the PeV region through measurements of the shape of Cerenkov lateral distributions. Data were collected during clear, moonless nights over three observing periods in 1995. Estimates of depths of shower maxima determined from the recorded Cerenkov lateral distributions align well with existing results at higher energies and suggest a mixed to heavy composition in the PeV region with no significant variation observed around the knee. The accuracy ofmore » composition determination is limited by uncertainties in the expected levels of depth of maximum predicted using different Monte-Carlo shower simulation models.« less

Far From ‘Easy’ Spectroscopy with the 8π and GRIFFIN Spectrometers at TRIUMF-ISAC

NASA Astrophysics Data System (ADS)

Garrett, P. E.; Radich, A. J.; Allmond, J. M.; Andreoiu, C.; Ball, G. C.; Bender, P. C.; Bianco, L.; Bildstein, V.; Bidaman, H.; Braid, R.; Burbadge, C.; Chagnon-Lessard, S.; Cross, D. S.; Deng, G.; Demand, G. A.; Diaz Varela, A.; Dunlop, M. R.; Dunlop, R.; Finlay, P.; Garnsworthy, A. B.; Grinyer, G. F.; Hackman, G.; Hadinia, B.; Ilyushkin, S.; Jigmeddorj, B.; Kisliuk, D.; Kuhn, K.; Laffoley, A. T.; Leach, K. G.; MacLean, A. D.; Michetti-Wilson, J.; Miller, D.; Moore, W.; Olaizola, B.; Orce, J. N.; Pearson, C. J.; Pore, J. L.; Rajabali, M. M.; Rand, E. T.; Sarazin, F.; Smith, J. K.; Starosta, K.; Sumithrarachchi, C. S.; Svensson, C. E.; Triambak, S.; Turko, J.; Wang, Z. M.; Wood, J. L.; Wong, J.; Williams, S. J.; Yates, S. W.; Zganjar, E. F.

2015-09-01

The 8π spectrometer, installed at the TRIUMF-ISAC facility, was the world's most sensitive γ-ray spectrometer dedicated to β-decay studies. A description is given of the 8π spectrometer and its auxiliary detectors including the plastic scintillator array SCEPTAR used for β-particle tagging and the Si(Li) array PACES for conversion electron measurements, its moving tape collector, and its data acquisition system. The recent investigation of the decay of 124Cs to study the nuclear structure of 124Xe, and how the β-decay measurements complemented previous Coulomb excitation studies, is highlighted, including the extraction of the deformation parameters for the excited 0+ bands in 124Xe. As a by-product, the decay scheme of the (7+) 124Cs isomeric state, for which the data from the PACES detectors were vital, was studied. Finally, a description of the new GRIFFIN spectrometer, which uses the same auxiliary detectors as the 8π spectrometer, is given.

Highly multiplexed signal readout for a time-of-flight positron emission tomography detector based on silicon photomultipliers.

PubMed

Cates, Joshua W; Bieniosek, Matthew F; Levin, Craig S

2017-01-01

Maintaining excellent timing resolution in the generation of silicon photomultiplier (SiPM)-based time-of-flight positron emission tomography (TOF-PET) systems requires a large number of high-speed, high-bandwidth electronic channels and components. To minimize the cost and complexity of a system's back-end architecture and data acquisition, many analog signals are often multiplexed to fewer channels using techniques that encode timing, energy, and position information. With progress in the development SiPMs having lower dark noise, after pulsing, and cross talk along with higher photodetection efficiency, a coincidence timing resolution (CTR) well below 200 ps FWHM is now easily achievable in single pixel, bench-top setups using 20-mm length, lutetium-based inorganic scintillators. However, multiplexing the output of many SiPMs to a single channel will significantly degrade CTR without appropriate signal processing. We test the performance of a PET detector readout concept that multiplexes 16 SiPMs to two channels. One channel provides timing information with fast comparators, and the second channel encodes both position and energy information in a time-over-threshold-based pulse sequence. This multiplexing readout concept was constructed with discrete components to process signals from a [Formula: see text] array of SensL MicroFC-30035 SiPMs coupled to [Formula: see text] Lu 1.8 Gd 0.2 SiO 5 (LGSO):Ce (0.025 mol. %) scintillators. This readout method yielded a calibrated, global energy resolution of 15.3% FWHM at 511 keV with a CTR of [Formula: see text] FWHM between the 16-pixel multiplexed detector array and a [Formula: see text] LGSO-SiPM reference detector. In summary, results indicate this multiplexing scheme is a scalable readout technique that provides excellent coincidence timing performance.

Scintillator based detector for fast-ion losses induced by magnetohydrodynamic instabilities in the ASDEX upgrade tokamak.

PubMed

García-Muñoz, M; Fahrbach, H-U; Zohm, H

2009-05-01

A scintillator based detector for fast-ion losses has been designed and installed on the ASDEX upgrade (AUG) tokamak [A. Herrmann and O. Gruber, Fusion Sci. Technol. 44, 569 (2003)]. The detector resolves in time the energy and pitch angle of fast-ion losses induced by magnetohydrodynamics (MHD) fluctuations. The use of a novel scintillator material with a very short decay time and high quantum efficiency allows to identify the MHD fluctuations responsible for the ion losses through Fourier analysis. A Faraday cup (secondary scintillator plate) has been embedded behind the scintillator plate for an absolute calibration of the detector. The detector is mounted on a manipulator to vary its radial position with respect to the plasma. A thermocouple on the inner side of the graphite protection enables the safety search for the most adequate radial position. To align the scintillator light pattern with the light detectors a system composed by a lens and a vacuum-compatible halogen lamp has been allocated within the detector head. In this paper, the design of the scintillator probe, as well as the new technique used to analyze the data through spectrograms will be described. A last section is devoted to discuss the diagnosis prospects of this method for ITER [M. Shimada et al., Nucl. Fusion 47, S1 (2007)].

Upgrades for GERDA Phase II

NASA Astrophysics Data System (ADS)

Heisel, Mark

2014-09-01

The Germanium Detector Array (GERDA) experiment is searching for the neutrinoless double beta decay (0 νββ) of 76Ge. It is a process that violates lepton number conservation and is predicted to occur in extensions of the standard model of particle physics. GERDA is located underground in the Gran Sasso National Laboratory (LNGS), Italy. An array of bare high-purity germanium detectors enriched in 76Ge is operated in a cryostat with 64 m3 of liquid argon supplemented by a 3 m thick shield of water. The experiment aims at exploring the 0 νββ decay up to a half life of 2 .1026 yr in two phases: Phase I of the experiment has been concluded last year. No signal is observed and the so far best limit is derived for the half life of the 0 νββ decay of 76Ge, T1/20ν <= 2 . 1 .1025 yr (90% C.L.), after an exposure of 21 . 6 kg .yr. The result refutes an earlier claim of discovery with high probability. The background index of 1 .10-2 cts/(keV .kg .yr) is lower by about one order of magnitude compared to previous experiments. At present the experiment is being upgraded to Phase II. The aim is to collect an exposure of 100kg .yr and further reduce the background by another order of magnitude to a level of <=10-3 cts/(keV .kg .yr). The detector mass will be increased by ~20 kg of new Broad Energy Germanium (BEGe) detectors from enriched 76Ge, which exhibit superior pulse shape discrimination and hence background rejection power. Low mass detector holders, cold front-end electronics, contacting and cabling schemes are redesigned for ultra low mass and radiopurity. In addition, a retractable liquid argon veto will be installed to efficiently suppress background events that induce scintillation in the liquid argon. A hybrid solution of photomultiplier tubes and silicon photomultipliers coupled to scintillating fibres was chosen. This talk gives an account of the results and these challenging modifications to meet our design goals. The Germanium Detector Array (GERDA) experiment is searching for the neutrinoless double beta decay (0 νββ) of 76Ge. It is a process that violates lepton number conservation and is predicted to occur in extensions of the standard model of particle physics. GERDA is located underground in the Gran Sasso National Laboratory (LNGS), Italy. An array of bare high-purity germanium detectors enriched in 76Ge is operated in a cryostat with 64 m3 of liquid argon supplemented by a 3 m thick shield of water. The experiment aims at exploring the 0 νββ decay up to a half life of 2 .1026 yr in two phases: Phase I of the experiment has been concluded last year. No signal is observed and the so far best limit is derived for the half life of the 0 νββ decay of 76Ge, T1/20 ν <= 2 . 1 .1025 yr (90% C.L.), after an exposure of 21 . 6 kg .yr. The result refutes an earlier claim of discovery with high probability. The background index of 1 .10-2 cts/(keV .kg .yr) is lower by about one order of magnitude compared to previous experiments. At present the experiment is being upgraded to Phase II. The aim is to collect an exposure of 100kg .yr and further reduce the background by another order of magnitude to a level of <=10-3 cts/(keV .kg .yr). The detector mass will be increased by ~20 kg of new Broad Energy Germanium (BEGe) detectors from enriched 76Ge, which exhibit superior pulse shape discrimination and hence background rejection power. Low mass detector holders, cold front-end electronics, contacting and cabling schemes are redesigned for ultra low mass and radiopurity. In addition, a retractable liquid argon veto will be installed to efficiently suppress background events that induce scintillation in the liquid argon. A hybrid solution of photomultiplier tubes and silicon photomultipliers coupled to scintillating fibres was chosen. This talk gives an account of the results and these challenging modifications to meet our design goals. On behalf of the GERDA Collaboration.

An efficient energy response model for liquid scintillator detectors

NASA Astrophysics Data System (ADS)

Lebanowski, Logan; Wan, Linyan; Ji, Xiangpan; Wang, Zhe; Chen, Shaomin

2018-05-01

Liquid scintillator detectors are playing an increasingly important role in low-energy neutrino experiments. In this article, we describe a generic energy response model of liquid scintillator detectors that provides energy estimations of sub-percent accuracy. This model fits a minimal set of physically-motivated parameters that capture the essential characteristics of scintillator response and that can naturally account for changes in scintillator over time, helping to avoid associated biases or systematic uncertainties. The model employs a one-step calculation and look-up tables, yielding an immediate estimation of energy and an efficient framework for quantifying systematic uncertainties and correlations.

ICP MS selection of radiopure materials for the GERDA experiment

NASA Astrophysics Data System (ADS)

di Vacri, M. L.; Nisi, S.; Cattadori, C.; Janicsko, J.; Lubashevskiy, A.; Smolnikov, A.; Walter, M.

2015-08-01

The GERDA (GERmanium Detector Array) experiment, located in the Gran Sasso Underground Laboratory (LNGS, Italy) aims to search for neutrinoless double beta (0νββ) decay of the 76Ge isotope. Both an ultra-low radioactivity background environment and active techniques to abate the residual background are required to reach the background index (of 10-3 counts/keV kg y) at the Qββ. In order to veto and suppress those events that partially deposit energy in Ge detectors, the readout of liquid argon (LAr) scintillation light (SL) has been implemented for the second GERDA experimental Phase. A double veto system has been designed and constructed using highly radiopure materials (scintillating fibers, wavelength shifters, polymeric foils, reflective foils). This work describes the study of lead, thorium and uranium ultra-trace content, performed at the LNGS Chemistry Laboratory by High Resolution Mass Spectrometry (HR ICP MS), for the selection of all materials involved in the construction of the veto system

Performance assessment study of the balloon-borne astronomical soft gamma-ray polarimeter PoGOLite

NASA Astrophysics Data System (ADS)

Arimoto, M.; Kanai, Y.; Ueno, M.; Kataoka, J.; Kawai, N.; Tanaka, T.; Yamamoto, K.; Takahashi, H.; Mizuno, T.; Fukazawa, Y.; Axelsson, M.; Kiss, M.; Marini Bettolo, C.; Carlson, P.; Klamra, W.; Pearce, M.; Chen, P.; Craig, B.; Kamae, T.; Madejski, G.; Ng, J. S. T.; Rogers, R.; Tajima, H.; Thurston, T. S.; Saito, Y.; Takahashi, T.; Gunji, S.; Bjornsson, C.-I.; Larsson, S.; Ryde, F.; Bogaert, G.; Varner, G.

2007-12-01

Measurements of polarization play a crucial role in the understanding of the dominant emission mechanism of astronomical sources. Polarized Gamma-ray Observer-Light version (PoGOLite) is a balloon-borne astronomical soft gamma-ray polarimeter at the 25 80 keV band. The PoGOLite detector consists of a hexagonal close-packed array of 217 Phoswich detector cells (PDCs) and side anti-coincidence shields (SASs) made of BGO crystals surrounding PDCs. Each PDC consists of a slow hollow scintillator, a fast scintillator and a BGO crystal that connects to a photomultiplier tube at the end. To examine the PoGOLite's capability and estimate the performance, we conducted experiments with the PDC using radioisotope 241Am. In addition, we compared this result with performance expected by Monte Carlo simulation with Geant4. As a result, we found that the actual PDC has the capability to detect a 100 m Crab source until 80 keV.

ICP MS selection of radiopure materials for the GERDA experiment

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

Di Vacri, M. L., E-mail: divacrim@lngs.infn.it; Dipartimento di Scienze Fisiche e Chimiche, University of L’Aquila, via Vetoio, 67100 L’Aquila; Nisi, S., E-mail: nisi@lngs.infn.it

2015-08-17

The GERDA (GERmanium Detector Array) experiment, located in the Gran Sasso Underground Laboratory (LNGS, Italy) aims to search for neutrinoless double beta (0νββ) decay of the {sup 76}Ge isotope. Both an ultra-low radioactivity background environment and active techniques to abate the residual background are required to reach the background index (of 10{sup −3} counts/keV kg y) at the Q{sub ββ}. In order to veto and suppress those events that partially deposit energy in Ge detectors, the readout of liquid argon (LAr) scintillation light (SL) has been implemented for the second GERDA experimental Phase. A double veto system has been designedmore » and constructed using highly radiopure materials (scintillating fibers, wavelength shifters, polymeric foils, reflective foils). This work describes the study of lead, thorium and uranium ultra-trace content, performed at the LNGS Chemistry Laboratory by High Resolution Mass Spectrometry (HR ICP MS), for the selection of all materials involved in the construction of the veto system.« less

Characterizing energy dependence and count rate performance of a dual scintillator fiber-optic detector for computed tomography

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

Hoerner, Matthew R., E-mail: mrh5038@ufl.edu; Stepusin, Elliott J.; Hyer, Daniel E.

Purpose: Kilovoltage (kV) x-rays pose a significant challenge for radiation dosimetry. In the kV energy range, even small differences in material composition can result in significant variations in the absorbed energy between soft tissue and the detector. In addition, the use of electronic systems in light detection has demonstrated measurement losses at high photon fluence rates incident to the detector. This study investigated the feasibility of using a novel dual scintillator detector and whether its response to changes in beam energy from scatter and hardening is readily quantified. The detector incorporates a tissue-equivalent plastic scintillator and a gadolinium oxysulfide scintillator,more » which has a higher sensitivity to scatter x-rays. Methods: The detector was constructed by coupling two scintillators: (1) small cylindrical plastic scintillator, 500 μm in diameter and 2 mm in length, and (2) 100 micron sheet of gadolinium oxysulfide 500 μm in diameter, each to a 2 m long optical fiber, which acts as a light guide to transmit scintillation photons from the sensitive element to a photomultiplier tube. Count rate linearity data were obtained from a wide range of exposure rates delivered from a radiological x-ray tube by adjusting the tube current. The data were fitted to a nonparalyzable dead time model to characterize the time response. The true counting rate was related to the reference free air dose air rate measured with a 0.6 cm{sup 3} Radcal{sup ®} thimble chamber as described in AAPM Report No. 111. Secondary electron and photon spectra were evaluated using Monte Carlo techniques to analyze ionization quenching and photon energy-absorption characteristics from free-in-air and in phantom measurements. The depth/energy dependence of the detector was characterized using a computed tomography dose index QA phantom consisting of nested adult head and body segments. The phantom provided up to 32 cm of acrylic with a compatible 0.6 cm{sup 3} calibrated ionization chamber to measure the reference air kerma. Results: Each detector exhibited counting losses of 5% when irradiated at a dose rate of 26.3 mGy/s (Gadolinium) and 324.3 mGy/s (plastic). The dead time of the gadolinium oxysulfide detector was determined to be 48 ns, while the dead time of the plastic scintillating detector was unable to accurately be calculated due to poor counting statistics from low detected count rates. Noticeable depth/energy dependence was observed for the plastic scintillator for depths greater than 16 cm of acrylic that was not present for measurements using the gadolinium oxysulfide scintillator, leading us to believe that quenching may play a larger role in the depth dependence of the plastic scintillator than the incident x-ray energy spectrum. When properly corrected for dead time effects, the energy response of the gadolinium oxysulfide scintillator is consistent with the plastic scintillator. Using the integrated dual detector method was superior to each detector individually as the depth-dependent measure of dose was correctable to less than 8% between 100 and 135 kV. Conclusions: The dual scintillator fiber-optic detector accommodates a methodology for energy dependent corrections of the plastic scintillator, improving the overall accuracy of the dosimeter across the range of diagnostic energies.« less

Characterizing energy dependence and count rate performance of a dual scintillator fiber-optic detector for computed tomography.

PubMed

Hoerner, Matthew R; Stepusin, Elliott J; Hyer, Daniel E; Hintenlang, David E

2015-03-01

Kilovoltage (kV) x-rays pose a significant challenge for radiation dosimetry. In the kV energy range, even small differences in material composition can result in significant variations in the absorbed energy between soft tissue and the detector. In addition, the use of electronic systems in light detection has demonstrated measurement losses at high photon fluence rates incident to the detector. This study investigated the feasibility of using a novel dual scintillator detector and whether its response to changes in beam energy from scatter and hardening is readily quantified. The detector incorporates a tissue-equivalent plastic scintillator and a gadolinium oxysulfide scintillator, which has a higher sensitivity to scatter x-rays. The detector was constructed by coupling two scintillators: (1) small cylindrical plastic scintillator, 500 μm in diameter and 2 mm in length, and (2) 100 micron sheet of gadolinium oxysulfide 500 μm in diameter, each to a 2 m long optical fiber, which acts as a light guide to transmit scintillation photons from the sensitive element to a photomultiplier tube. Count rate linearity data were obtained from a wide range of exposure rates delivered from a radiological x-ray tube by adjusting the tube current. The data were fitted to a nonparalyzable dead time model to characterize the time response. The true counting rate was related to the reference free air dose air rate measured with a 0.6 cm(3) Radcal(®) thimble chamber as described in AAPM Report No. 111. Secondary electron and photon spectra were evaluated using Monte Carlo techniques to analyze ionization quenching and photon energy-absorption characteristics from free-in-air and in phantom measurements. The depth/energy dependence of the detector was characterized using a computed tomography dose index QA phantom consisting of nested adult head and body segments. The phantom provided up to 32 cm of acrylic with a compatible 0.6 cm(3) calibrated ionization chamber to measure the reference air kerma. Each detector exhibited counting losses of 5% when irradiated at a dose rate of 26.3 mGy/s (Gadolinium) and 324.3 mGy/s (plastic). The dead time of the gadolinium oxysulfide detector was determined to be 48 ns, while the dead time of the plastic scintillating detector was unable to accurately be calculated due to poor counting statistics from low detected count rates. Noticeable depth/energy dependence was observed for the plastic scintillator for depths greater than 16 cm of acrylic that was not present for measurements using the gadolinium oxysulfide scintillator, leading us to believe that quenching may play a larger role in the depth dependence of the plastic scintillator than the incident x-ray energy spectrum. When properly corrected for dead time effects, the energy response of the gadolinium oxysulfide scintillator is consistent with the plastic scintillator. Using the integrated dual detector method was superior to each detector individually as the depth-dependent measure of dose was correctable to less than 8% between 100 and 135 kV. The dual scintillator fiber-optic detector accommodates a methodology for energy dependent corrections of the plastic scintillator, improving the overall accuracy of the dosimeter across the range of diagnostic energies.

The SNO+ Scintillator Purification Plant and Projected Sensitivity to Solar Neutrinos in the Pure Scintillator Phase

NASA Astrophysics Data System (ADS)

Pershing, Teal; SNO+ Collaboration

2016-03-01

The SNO+ detector is a neutrino and neutrinoless double-beta decay experiment utilizing the renovated SNO detector. In the second phase of operation, the SNO+ detector will contain 780 tons of organic liquid scintillator composed of 2 g/L 2,5-diphenyloxazole (PPO) in linear alkylbenzene (LAB). In this phase, SNO+ will strive to detect solar neutrinos in the sub-MeV range, including CNO production neutrinos and pp production neutrinos. To achieve the necessary detector sensitivity, a four-part scintillator purification plant has been constructed in SNOLAB for the removal of ionic and radioactive impurities. We present an overview of the SNO+ scintillator purification plant stages, including distillation, water extraction, gas stripping, and metal scavenger columns. We also give the projected SNO+ sensitivities to various solar-produced neutrinos based on the scintillator plant's projected purification efficiency.

Multisector scintillation detector with fiber-optic light collection

NASA Astrophysics Data System (ADS)

Ampilogov, N. V.; Denisov, S. P.; Kokoulin, R. P.; Petrukhin, A. A.; Prokopenko, N. N.; Shulzhenko, I. A.; Unatlokov, I. B.; Yashin, I. I.

2017-07-01

A new type of scintillation detector for the use in high energy physics is described. The octagonal detector consists of eight triangular scintillator sectors with total area of 1 m2. Each sector represents two plates of 2 cm thick plastic scintillator. Seven 1 mm thick WLS fibers are laid evenly between the plates. The space between the fibers is filled with silicone compound to provide better light collection. Fiber ends from all eight sectors are gathered in the central part of the detector into a bunch and docked to the cathode of a FEU-115m photomultiplier. The read-out of the counter signals is carried out from 7th and 12th dynodes, providing a wide dynamic range up to about 10000 particles. The front-end electronics of the detector is based on the flash-ADC with a sampling frequency of 200 MHz. The features of detecting and recording systems of the multisector scintillation detector (MSD) and the results of its testing are discussed.

Neutron detector and fabrication method thereof

DOEpatents

Bhandari, Harish B.; Nagarkar, Vivek V.; Ovechkina, Olena E.

2016-08-16

A neutron detector and a method for fabricating a neutron detector. The neutron detector includes a photodetector, and a solid-state scintillator operatively coupled to the photodetector. In one aspect, the method for fabricating a neutron detector includes providing a photodetector, and depositing a solid-state scintillator on the photodetector to form a detector structure.

First light from a kilometer-baseline Scintillation Auroral GPS Array.

PubMed

Datta-Barua, S; Su, Y; Deshpande, K; Miladinovich, D; Bust, G S; Hampton, D; Crowley, G

2015-05-28

We introduce and analyze the first data from an array of closely spaced Global Positioning System (GPS) scintillation receivers established in the auroral zone in late 2013 to measure spatial and temporal variations in L band signals at 100-1000 m and subsecond scales. The seven receivers of the Scintillation Auroral GPS Array (SAGA) are sited at Poker Flat Research Range, Alaska. The receivers produce 100 s scintillation indices and 100 Hz carrier phase and raw in-phase and quadrature-phase samples. SAGA is the largest existing array with baseline lengths of the ionospheric diffractive Fresnel scale at L band. With an initial array of five receivers, we identify a period of simultaneous amplitude and phase scintillation. We compare SAGA power and phase data with collocated 630.0 nm all-sky images of an auroral arc and incoherent scatter radar electron precipitation measurements, to illustrate how SAGA can be used in multi-instrument observations for subkilometer-scale studies. A seven-receiver Scintillation Auroral GPS Array (SAGA) is now at Poker Flat, Alaska SAGA is the largest subkilometer array to enable phase/irregularities studies Simultaneous scintillation, auroral arc, and electron precipitation are observed.

First light from a kilometer-baseline Scintillation Auroral GPS Array

PubMed Central

Datta-Barua, S; Su, Y; Deshpande, K; Miladinovich, D; Bust, G S; Hampton, D; Crowley, G

2015-01-01

We introduce and analyze the first data from an array of closely spaced Global Positioning System (GPS) scintillation receivers established in the auroral zone in late 2013 to measure spatial and temporal variations in L band signals at 100–1000 m and subsecond scales. The seven receivers of the Scintillation Auroral GPS Array (SAGA) are sited at Poker Flat Research Range, Alaska. The receivers produce 100 s scintillation indices and 100 Hz carrier phase and raw in-phase and quadrature-phase samples. SAGA is the largest existing array with baseline lengths of the ionospheric diffractive Fresnel scale at L band. With an initial array of five receivers, we identify a period of simultaneous amplitude and phase scintillation. We compare SAGA power and phase data with collocated 630.0 nm all-sky images of an auroral arc and incoherent scatter radar electron precipitation measurements, to illustrate how SAGA can be used in multi-instrument observations for subkilometer-scale studies. Key Points A seven-receiver Scintillation Auroral GPS Array (SAGA) is now at Poker Flat, Alaska SAGA is the largest subkilometer array to enable phase/irregularities studies Simultaneous scintillation, auroral arc, and electron precipitation are observed PMID:26709318

A logarithmic detection system suitable for a 4π array

NASA Astrophysics Data System (ADS)

Westfall, G. D.; Yurkon, J. E.; van der Plicht, J.; Koenig, Z. M.; Jacak, B. V.; Fox, R.; Crawley, G. M.; Maier, M. R.; Hasselquist, B. E.; Tickle, R. S.; Horn, D.

1985-08-01

A low pressure multiwire proportional counter, a Bragg curve counter, and an array of CaF2/plastic scintillator telescopes have been developed in a geometry suitable for close packing into a 4π detector designed to study nucleus-nucleus reactions at 100-200 MeV/nucleon. The multiwire counter is hexagonal in shape and gives X-Y position information using resistive charge division from nichrome-coated stretched polypropylene foils. The Bragg curve counter is a hexagonal pyramid with the charge taken from a Frisch gridded anode. A field shaping grid gives the Bragg curve counter a radial field. The scintillator telescopes are shaped as truncated triangular pyramids such that when stacked together they form a truncated hexagonal pyramid. The light signal of the CaF2-plastic combination is read with one phototube using a phoswich technique to separate the ΔE signal from the E signal. The entire system has been tested so far for particles with 1 <= Z <= 18 and gives good position, charge, and time resolution.

Solid state tritium detector for biomedical applications

NASA Astrophysics Data System (ADS)

Gordon, J. S.; Farrell, R.; Daley, K.; Oakes, C. E.

1994-08-01

Radioactive labeling of proteins is a very important technique used in biomedical research to identify, isolate, and investigate the expression and properties of proteins in biological systems. In such procedures, the preferred radiolabel is often tritium. Presently, binding assays involving tritium are carried out using inconvenient and expensive techniques which rely on the use of scintillation fluid counting systems. This traditional method involves both time-consuming laboratory protocols and the generation of substantial quantities of radioactive and chemical waste. We have developed a novel technology to measure the tritium content of biological specimens that does not rely on scintillation fluids. The tritiated samples can be positioned directly under a large area, monolithic array of specially prepared avalanche photodiodes (APDs) which record the tritium activity distribution at each point within the field of view of the array. The 1 mm(sup 2) sensing elements exhibit an intrinsic tritium beta detection efficiency of 27% with high gain uniformity and very low cross talk.

An investigation of high-multiplicity gamma events in pp collisions with c.m. energies between 22 and 62 GeV

NASA Technical Reports Server (NTRS)

Dell, G. F.; Uto, H.; Yuan, L. C. L.; Amaldi, E.; Beneventano, M.; Borgia, B.; Pistilli, P.; Sestili, I.; Dooher, J.

1976-01-01

An experiment was conducted at the CERN intersecting storage rings using colliding proton beams to investigate high-multiplicity gamma-ray events. The objective of the study was to reveal certain features of multiple pion production as well as other possible mechanisms of gamma-ray production. The detector system consisted of ten planes of spark chambers, three scintillation counter hodoscopes and two arrays of lead-glass Cerenkov counters, the first array containing 16 counters and the second, 60 counters. The event trigger was obtained from the Cerenkov counters, and the energies in all the Cerenkov counters after trigger, as well as the information on all the charged particles given by the scintillation counters and spark chambers were recorded on magnetic tape. The relationship between the number of gamma-rays per event and the number of Cerenkov counters triggered by a neutral secondary was established by means of a Monte Carlo calculation.

Correlated fission data measurements with DANCE and NEUANCE

DOE PAGES

Jandel, Marian; Baramsai, Baramsai; Bredeweg, Todd Allen; ...

2017-11-16

To enhance the capabilities of the DANCE array, a new detector array NEUANCE was developed to enable simultaneous measurements of prompt fission neutrons and γ rays. NEUANCE was designed and constructed using 21 stilbene organic scintillator crystals. It was installed in the central cavity of the DANCE array. Signals from the 160 BaF 2 detectors of DANCE and the 21 detectors of NEUANCE were merged into a newly designed high-density high-throughput data acquisition system. The excellent pulse shape discrimination properties of stilbene enabled detection of neutrons with energy thresholds as low as 30–40 keVee. A fission reaction tagging method wasmore » developed using a NEUANCE γ-ray or neutron signal. The probability of detecting a neutron from the spontaneous fission of 252Cf using NEUANCE is 47%. New correlated data for prompt fission neutrons and prompt fission rays were obtained for 252Cf using this high detection efficiency experimental setup. In conclusion, average properties of prompt fission neutron emission as a function of prompt fission γ-ray quantities were also obtained, suggesting that neutron and γ-ray emission in fission are correlated.« less

Utilization of wavelength-shifting fibers coupled to ZnS(Ag) and plastic scintillator for simultaneous detection of alpha/beta particles

NASA Astrophysics Data System (ADS)

Ifergan, Y.; Dadon, S.; Israelashvili, I.; Osovizky, A.; Gonen, E.; Yehuda-Zada, Y.; Smadja, D.; Knafo, Y.; Ginzburg, D.; Kadmon, Y.; Cohen, Y.; Mazor, T.

2015-06-01

Low level radioactive surface contamination measurements require lightweight, large area and high efficiency detector. In most existing scintillation detectors there is a tradeoff between effective area and scintillation light collection. By using wavelength shifting (WLS) fibers the scintillation light may be collected efficiently also in a large area detector. In this study, WLS fibers were coupled to a beta sensitive plastic scintillator layer and to a alpha sensitive silver-activated zinc sulfide ZnS(Ag) layer for detecting both alpha and beta particles. The WLS fibers collect the scintillation light from the whole detector and transfer it to a single PMT. This first prototype unique configuration enables monitoring radioactive contaminated surfaces by both sides of the detector and provides high gamma rejection. In this paper, the detector structure, as well as the detector's measured linear response, will be described. The measured detection efficiency of 238Pu alpha particles (5.5 MeV) is 63%. The measured detection efficiency for beta particles is 89% for 90Sr-90Y (average energy of 195.8 keV, 934.8 keV), 50% for 36Cl (average energy of 251.3 keV), and 35% for 137Cs (average energy of 156.8 keV).

Scintillator-fiber charged particle track-imaging detector

NASA Technical Reports Server (NTRS)

Binns, W. R.; Israel, M. H.; Klarmann, J.

1983-01-01

A scintillator-fiber charged-particle track-imaging detector was developed using a bundle of square cross section plastic scintillator fiber optics, proximity focused onto an image intensified charge injection device (CID) camera. The tracks of charged particle penetrating into the scintillator fiber bundle are projected onto the CID camera and the imaging information is read out in video format. The detector was exposed to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei and images of their tracks were obtained. Details of the detector technique, properties of the tracks obtained, and preliminary range measurements of 15 MeV protons stopping in the fiber bundle are presented.

Cryogenic phonon-scintillation detectors with PMT readout for rare event search experiments

NASA Astrophysics Data System (ADS)

Zhang, X.; Lin, J.; Mikhailik, V. B.; Kraus, H.

2016-06-01

Cryogenic phonon-scintillation detectors (CPSD) for rare event search experiments require reliable, efficient and robust photon detectors that can resolve individual photons in a scintillation event. We report on a cryogenic detector containing a scintillating crystal, equipped with an NTD-Ge phonon sensor and a photon detector based on a low-temperature photomultiplier tube (PMT) that is powered by a Cockcroft-Walton generator. Here we present results from the characterisation of two detector modules, one with CaWO4, the other with CaMoO4 as scintillator. The energy resolutions (FWHM) at 122.1 keV for the scintillation/PMT channel are 19.9% and 29.7% respectively for CaWO4 and CaMoO4 while the energy resolutions (FWHM) for the phonon channels are 2.17 keV (1.8%) and 0.97 keV (0.79%). These characteristics compare favourably with other CPSDs currently used in cryogenic rare-event search experiments. The detection module with PMT readout benefits from the implementation of a well-understood, reliable, and commercially available component and improved time resolution, while retaining the major advantages of conventional CPSD, such as high sensitivity, resolving power and discrimination ability.

Lead carbonate scintillator materials

DOEpatents

Derenzo, Stephen E.; Moses, William W.

1991-01-01

Improved radiation detectors containing lead carbonate or basic lead carbonate as the scintillator element are disclosed. Both of these scintillators have been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to other known scintillator materials. The radiation detectors disclosed are favorably suited for use in general purpose detection and in medical uses.

Positron Scanner for Locating Brain Tumors

DOE R&D Accomplishments Database

Rankowitz, S.; Robertson, J. S.; Higinbotham, W. A.; Rosenblum, M. J.

1962-03-01

A system is described that makes use of positron emitting isotopes for locating brain tumors. This system inherently provides more information about the distribution of radioactivity in the head in less time than existing scanners which use one or two detectors. A stationary circular array of 32 scintillation detectors scans a horizontal layer of the head from many directions simultaneously. The data, consisting of the number of counts in all possible coincidence pairs, are coded and stored in the memory of a Two-Dimensional Pulse-Height Analyzer. A unique method of displaying and interpreting the data is described that enables rapid approximate analysis of complex source distribution patterns. (auth)

Measurement of the 238U neutron-capture cross section and gamma-emission spectra from 10 eV to 100 keV using the DANCE detector at LANSCE

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

Ullmann, John L; Couture, A J; Keksis, A L

2010-01-01

A careful new measurement of the {sup 238}U(n,{gamma}) cross section from 10 eV to 100 keV has been made using the DANCE detector at LANSCE. DANCE is a 4{pi} calorimetric scintillator array consisting of 160 BaF{sub 2} crystals. Measurements were made on a 48 mg/cm{sup 2} depleted uranium target. The cross sections are in general good agreement with previous measurements. The gamma-ray emission spectra, as a function of gamma multiplicity, were also measured and compared to model calculations.

20 years of cosmic muons research performed in IFIN-HH

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

Mitrica, Bogdan

2012-11-20

During the last two decades a modern direction in particle physics research has been developed in IFIN-HH Bucharest, Romania. The history started with the WILLI detector built in IFIN-HH Bucharest in collaboration with KIT Karlsruhe (formerly Forschungszentrum Karlsruhe). The detector was designed for measurements of the low energy muon charge ratio (< 1GeV) based on a delayed coincidence method, measuring the decay time of the muons stopped in the detector: the positive muons decay freely, but the negative muons are captured in the atom thus creating muonic atoms and decay depending on the nature of the host atom. In amore » first configuration, the WILLI detector was placed in a fixed position for measuring vertical muons. Further WILLI has been transformed in a rotatable device which allows directional measurements of muon charge ratio and muon flux. The results exhibit a pronounced azimuthal asymmetry (East-West effect) due to the different in fluence of the geomagnetic field on the trajectories of positive and negative muons in air. In parallel, flux measurement, taking into account muon events with nergies > 0.4GeV, show a diurnal modulation of the muon flux. The analysis of the muon events for energies < 0.6GeV reveals an aperiodic variation of the muon flux. A new detection system performing coincidence measurements between the WILLI calorimeter and a small array of 12 scintillators plates has been installed in IFIN-HH starting from the autumn of 2010. The aim of the system is to investigate muon charge ratio from individual EAS by using the mini-array as trigger for the WILLI calorimeter. Such experimental studies could provide detailed information on hadronic interaction models and primary cosmic ray composition at energies around 10{sup 15}eV. Simulation studies and preliminary experimental tests, regarding the performances of the mini-array, have been performed using H and Fe primaries, with energies in a range 10{sup 13}eV - 10{sup 15}eV. The results show detailed effects of the direction of EAS incidence relative to the geomagnetic field, depending, in particular, of the primary mass. Based on the results, we can say that WILLI-EAS experiment could be used for testing the hadronic interaction models. Measurements of the high energy muon flux in underground of the salt mine from Slanic Prahova, Romania was performed using a new mobile detector developed in IFIN-HH, Bucharest. Consisting of 2 scintillator plates measuring in coincidence, the detector is installed on a van which facilitates measurements on different positions at surface or in underground. The detector was used to measure muon fluxes in different locations at surface or in underground. The detector was used to measure muon fluxes at different sites of Romania and in the underground of the salt mines from Slanic Prahova, Romania where IFIN-HH has a modern underground laboratory. New methods for the detection of cosmic ray muons are investigated in our institute based on scintillator techniques using optical fiber and MPPC photodyodes.« less

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%.

A FADC-Based Data Acquisition System for the KASCADE-Grande Experiment

NASA Astrophysics Data System (ADS)

Walkowiak, W.; Antoni, T.; Apel, W. D.; Badea, F.; Bekk, K.; Bercuci, A.; Bertaina, M.; Blumer, H.; Bozdog, H.; Brancus, I. M.; Bruggemann, M.; Buchholz, P.; Buttner, C.; Chiavassa, A.; Daumiller, K.; Dipierro, F.; Doll, P.; Engel, R.; Engler, J.; Febler, F.; Ghia, P. L.; Gils, H. J.; Glasstetter, R.; Haungs, A.; Heck, D.; Horandel, J. R.; Kampert, K.-H.; Klages, H. O.; Kolotaev, Y.; Maier, G.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Muller, M.; Navarra, G.; Obenland, R.; Oehlschlager, J.; Ostapchenko, S.; Over, S.; Petcu, M.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler, H.; Scholz, J.; Stumpert, M.; Thouw, T.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Valchierotti, S.; Vanburen, J.; Weindl, A.; Wochele, J.; Zabierowski, J.; Zagromski, S.; Zimmermann, D.

2006-02-01

We present the design and first test results of a new FADC-based data acquisition (DAQ) system for the Grande array of the KASCADE-Grande experiment. The original KASCADE experiment at the Forschungszentrum Karlsruhe, Germany, has been extended by 37 detector stations of the former EAS-TOP experiment (Grande array)to provide sensitivity to energies of primary particles from the cosmos of up to $10^{18}$ eV. The new FADC-based DAQ system will improve the quality of the data taken by the Grande array by digitizing the scintillator signals with a 250 MHz sampling rate. events per second. Two Grande stations have been equipped with the FADC-based data acquisition system and first data are shown.

The generalized centroid difference method for picosecond sensitive determination of lifetimes of nuclear excited states using large fast-timing arrays

NASA Astrophysics Data System (ADS)

Régis, J.-M.; Mach, H.; Simpson, G. S.; Jolie, J.; Pascovici, G.; Saed-Samii, N.; Warr, N.; Bruce, A.; Degenkolb, J.; Fraile, L. M.; Fransen, C.; Ghita, D. G.; Kisyov, S.; Koester, U.; Korgul, A.; Lalkovski, S.; Mărginean, N.; Mutti, P.; Olaizola, B.; Podolyak, Z.; Regan, P. H.; Roberts, O. J.; Rudigier, M.; Stroe, L.; Urban, W.; Wilmsen, D.

2013-10-01

A novel method for direct electronic “fast-timing” lifetime measurements of nuclear excited states via γ-γ coincidences using an array equipped with N∈N equally shaped very fast high-resolution LaBr3(Ce) scintillator detectors is presented. Analogous to the mirror symmetric centroid difference method, the generalized centroid difference method provides two independent “start” and “stop” time spectra obtained by a superposition of the N(N-1)γ-γ time difference spectra of the N detector fast-timing system. The two fast-timing array time spectra correspond to a forward and reverse gating of a specific γ-γ cascade. Provided that the energy response and the electronic time pick-off of the detectors are almost equal, a mean prompt response difference between start and stop events is calibrated and used as a single correction for lifetime determination. These combined fast-timing arrays mean γ-γ time-walk characteristics can be determined for 40 keV

Development of a thin scintillation films fission-fragment detector and a novel neutron source

NASA Astrophysics Data System (ADS)

Rusev, G.; Jandel, M.; Baramsai, B.; Bond, E. M.; Bredeweg, T. A.; Couture, A.; Daum, J. K.; Favalli, A.; Ianakiev, K. D.; Iliev, M. L.; Mosby, S.; Roman, A. R.; Springs, R. K.; Ullmann, J. L.; Walker, C. L.

2015-08-01

Investigation of prompt fission and neutron-capture Υ rays from fissile actinide samples at the Detector for Advanced Neutron Capture Experiments (DANCE) requires use of a fission-fragment detector to provide a trigger or a veto signal. A fission-fragment detector based on thin scintillating films and silicon photomultipliers has been built to serve as a trigger/veto detector in neutron-induced fission measurements at DANCE. The fissile material is surrounded by scintillating films providing a 4π detection of the fission fragments. The scintillations were registered with silicon photomultipliers. A measurement of the 235U(n,f) reaction with this detector at DANCE revealed a correct time-of-flight spectrum and provided an estimate for the efficiency of the prototype detector of 11.6(7)%. Design and test measurements with the detector are described. A neutron source with fast timing has been built to help with detector-response measurements. The source is based on the neutron emission from the spontaneous fission of 252Cf and the same type of scintillating films and silicon photomultipliers. Overall time resolution of the source is 0.3 ns. Design of the source and test measurements with it are described. An example application of the source for determining the neutron/gamma pulse-shape discrimination by a stilbene crystal is given.

Scintillator-fiber charged-particle track-imaging detector

NASA Technical Reports Server (NTRS)

Binns, W. R.; Israel, M. H.; Klarmann, J.

1983-01-01

A scintillator-fiber charged-particle track-imaging detector has been developed using a bundle of square cross-section plastic scintillator fiber optics, proximity focused onto an image intensified Charge Injection Device (CID) camera. Detector to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei have been exposed and images of their tracks are obtained. This paper presents details of the detector technique, properties of the tracks obtained, and range measurements of 15 MeV protons stopping in the fiber bundle.

Characterization of Pr:LuAG scintillating crystals for X-ray spectroscopy

NASA Astrophysics Data System (ADS)

Bertoni, R.; Bonesini, M.; Cervi, T.; Clemenza, M.; De Bari, A.; Falcone, A.; Mazza, R.; Menegolli, A.; Nastasi, M.; Rossella, M.

2016-07-01

The main features of the Pr doped Lu3Al5O12 (Pr:LuAG) scintillating crystals for X-ray spectroscopy applications have been studied using different radioactive sources and photo-detectors. Pr:LuAG is cheaper, compared to a Germanium detector, but with remarkable properties which make it useful for many applications, from fundamental physics measurements to the PET imaging for medical purposes: high density, elevate light yield, fast response, high energy resolution, no hygroscopicity. A sample of Pr:LuAG crystals with 14 mm×14 mm surface area and 13 mm thickness and a NaI crystal of the same surface and 26 mm thickness used as a reference have been characterized with several radioactive sources, emitting photons in the range 100-1000keV. Different light detectors were adopted for the Pr:LuAG studies, sensitive to its UV emission (peak at 310 nm): a 3 in. PMT (Hamamatsu R11065) and new arrays of Hamamatsu SiPM S13361, with siliconic resin as a window. Preliminary results are presented on the performance of the Pr:LuAG crystals, to be mounted in a 2 × 2 array to be tested in the 2015 run of the FAMU experiment at RIKEN-RAL muon facility. The goal is the detection of the X-rays (around 130 keV) emitted during the de-excitation processes of the muonic hydrogen after the excitation with an IR laser with wavelength set at the resonance of the hyperfine splitting, to measure the muonic atom proton radius with unprecedented precision.

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.

Measurement of the 97Mo(n ,γ ) reaction with the DANCE γ calorimeter array

NASA Astrophysics Data System (ADS)

Walker, C. L.; Krtička, M.; Baramsai, B.; Bečvář, F.; Bredeweg, T. A.; Chyzh, A.; Haight, R. C.; Jandel, M.; Kroll, J.; Mitchell, G. E.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Valenta, S.; Wilhelmy, J. B.

2015-07-01

Spectra of γ rays following the 97Mo(n ,γ ) reaction were measured as a function of incident neutron energy with the DANCE (Detector for Advanced Neutron Capture Experiments) array of 160 BaF2 scintillation detectors at the Los Alamos Neutron Science Center using an enriched 97Mo target. These spectra were used for the assignment of spins of the 97Mo resonances up to neutron energy En=1.7 keV, as well as in the study of photon strength functions (PSFs) in 98Mo. Analysis of the spectra with the nuclear statistical model showed that they can be well reproduced with the same PSF models which well described the γ decay following slow neutron capture in 95Mo. On the other hand, the spectra are inconsistent with PSFs describing some other experimental data in 98Mo.

A computer controlled television detector for light, X-rays and particles

NASA Technical Reports Server (NTRS)

Kalata, K.

1981-01-01

A versatile, high resolution, software configurable, two-dimensional intensified vidicon quantum detector system has been developed for multiple research applications. A thin phosphor convertor allows the detection of X-rays below 20 keV and non-relativistic particles in addition to visible light, and a thicker scintillator can be used to detect X-rays up to 100 keV and relativistic particles. Faceplates may be changed to allow any active area from 1 to 40 mm square, and active areas up to 200 mm square are possible. The image is integrated in a digital memory on any software specified array size up to 4000 x 4000. The array size is selected to match the spatial resolution, which ranges from 10 to 100 microns depending on the operating mode, the active area, and the photon or particle energy. All scan and data acquisition parameters are under software control to allow optimal data collection for each application.

Calculations and measurements of the scintillator-to-water stopping power ratio of liquid scintillators for use in proton radiotherapy.

PubMed

Ingram, W Scott; Robertson, Daniel; Beddar, Sam

2015-03-11

Liquid scintillators are a promising detector for high-resolution three-dimensional proton therapy dosimetry. Because the scintillator comprises both the active volume of the detector and the phantom material, an ideal scintillator will exhibit water equivalence in its radiological properties. One of the most fundamental of these is the scintillator's stopping power. The objective of this study was to compare calculations and measurements of scintillator-to-water stopping power ratios to evaluate the suitability of the liquid scintillators BC-531 and OptiPhase HiSafe 3 for proton dosimetry. We also measured the relative scintillation output of the two scintillators. Both calculations and measurements show that the linear stopping power of OptiPhase is significantly closer to water than that of BC-531. BC-531 has a somewhat higher scintillation output. OptiPhase can be mixed with water at high concentrations, which further improves its scintillator-to-water stopping power ratio. However, this causes the solution to become cloudy, which has a negative impact on the scintillation output and spatial resolution of the detector. OptiPhase is preferred over BC-531 for proton dosimetry because its density and scintillator-to-water stopping power ratio are more water equivalent.

Radioactive contamination of scintillators

NASA Astrophysics Data System (ADS)

Danevich, F. A.; Tretyak, V. I.

2018-03-01

Low counting experiments (search for double β decay and dark matter particles, measurements of neutrino fluxes from different sources, search for hypothetical nuclear and subnuclear processes, low background α, β, γ spectrometry) require extremely low background of a detector. Scintillators are widely used to search for rare events both as conventional scintillation detectors and as cryogenic scintillating bolometers. Radioactive contamination of a scintillation material plays a key role to reach low level of background. Origin and nature of radioactive contamination of scintillators, experimental methods and results are reviewed. A programme to develop radiopure crystal scintillators for low counting experiments is discussed briefly.

Lead carbonate scintillator materials

DOEpatents

Derenzo, S.E.; Moses, W.W.

1991-05-14

Improved radiation detectors containing lead carbonate or basic lead carbonate as the scintillator element are disclosed. Both of these scintillators have been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to other known scintillator materials. The radiation detectors disclosed are favorably suited for use in general purpose detection and in medical uses. 3 figures.

First results of the (n,γ) EXILL campaigns at the Institut Laue Langevin using EXOGAM and FATIMA

NASA Astrophysics Data System (ADS)

Jolie, J.; Régis, J.-M.; Wilmsen, D.; Ahmed, S.; Pfeiffer, M.; Saed-Samii, N.; Warr, N.; Blanc, A.; Jentschel, M.; Köster, U.; Mutti, P.; Soldner, T.; Simpson, G.; de France, G.; Urban, W.; Bruce, A. M.; Roberts, O. J.; Fraile, L. M.; Paziy, V.; Ignatov, A.; Ilieva, S.; Kröll, Th; Scheck, M.; Thürauf, M.; Ivanova, D.; Kisyov, S.; Lalkovski, S.; Podolyak, Zs; Regan, P. H.; Korten, W.; Habs, D.; Thirolf, P. G.; Ur, C. A.

2014-09-01

At the PF1B cold neutron beam line at the Institut Laue Langevin the EXILL array consisting of EXOGAM, GASP and LOHENGRIN detectors was used to perform (n,γ) measurements under very high coincidence rates. About ten different reactions were then measured in autumn 2012. In spring 2013 the EXOGAM array was combined with 16 LaBr3(Ce) scintillators in the FATIMA@EXILL campaign for the measurement of lifetimes using the generalised centroid difference method. We report on the properties of both set-ups and present first results on Pt isotopes from both campaigns.

DESCANT - Testing and Commissioning

NASA Astrophysics Data System (ADS)

Bildstein, Vinzenz; Garrett, P. E.; Bandyopadhay, D.; Bangay, J.; Bianco, L.; Demand, G.; Hadinia, B.; Leach, K. G.; Sumithrarachchi, C.; Turko, J.; Wong, J.; Ashley, S. F.; Crider, B. P.; McEllistrem, M. T.; Peters, E. E.; Prados-Estévez, F. M.; Yates, S. W.; Vanhoy, J. R.; Ball, G. C.; Bishop, D. P.; Garnsworthy, A. B.; Hackman, G.; Pearson, C. J.; Shaw, B.; Sarazin, F.

2017-09-01

The DESCANT array at TRIUMF is designed to detect neutrons from RIB experiments. DESCANT is composed of 70 close-packed deuterated organic liquid scintillators coupled to digital fast read-out ADC modules. This configuration permits online pulse-shape discrimination between neutron and γ-ray events. A prototype detector was tested with monoenergetic neutrons at the University of Kentucky Accelerator Laboratory. The data from these tests was compared to Geant4 simulations. A first commissioning experiment of the full array, using the decay of Cs 145 - 146 , was performed in August 2016. The results of the tests and a preliminary analysis of the commissioning experiment will be presented.

Plastic scintillator detector for pulsed flux measurements

NASA Astrophysics Data System (ADS)

Kadilin, V. V.; Kaplun, A. A.; Taraskin, A. A.

2017-01-01

A neutron detector, providing charged particle detection capability, has been designed. The main purpose of the detector is to measure pulsed fluxes of both charged particles and neutrons during scientific experiments. The detector consists of commonly used neutron-sensitive ZnS(Ag) / 6LiF scintillator screens wrapping a layer of polystyrene based scintillator (BC-454, EJ-254 or equivalent boron loaded plastic). This type of detector design is able to log a spatial distribution of events and may be scaled to any size. Different variations of the design were considered and modelled in specialized toolkits. The article presents a review of the detector design features as well as simulation results.

Testing a new NIF neutron time-of-flight detector with a bibenzyl scintillator on OMEGA.

PubMed

Glebov, V Yu; Forrest, C; Knauer, J P; Pruyne, A; Romanofsky, M; Sangster, T C; Shoup, M J; Stoeckl, C; Caggiano, J A; Carman, M L; Clancy, T J; Hatarik, R; McNaney, J; Zaitseva, N P

2012-10-01

A new neutron time-of-flight (nTOF) detector with a bibenzyl crystal as a scintillator has been designed and manufactured for the National Ignition Facility (NIF). This detector will replace a nTOF20-Spec detector with an oxygenated xylene scintillator currently operational on the NIF to improve the areal-density measurements. In addition to areal density, the bibenzyl detector will measure the D-D and D-T neutron yield and the ion temperature of indirect- and direct-drive-implosion experiments. The design of the bibenzyl detector and results of tests on the OMEGA Laser System are presented.

Characterization of scintillator-based detectors for few-ten-keV high-spatial-resolution x-ray imaging

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

Larsson, Jakob C., E-mail: jakob.larsson@biox.kth.se; Lundström, Ulf; Hertz, Hans M.

2016-06-15

Purpose: High-spatial-resolution x-ray imaging in the few-ten-keV range is becoming increasingly important in several applications, such as small-animal imaging and phase-contrast imaging. The detector properties critically influence the quality of such imaging. Here the authors present a quantitative comparison of scintillator-based detectors for this energy range and at high spatial frequencies. Methods: The authors determine the modulation transfer function, noise power spectrum (NPS), and detective quantum efficiency for Gadox, needle CsI, and structured CsI scintillators of different thicknesses and at different photon energies. An extended analysis of the NPS allows for direct measurements of the scintillator effective absorption efficiency andmore » effective light yield as well as providing an alternative method to assess the underlying factors behind the detector properties. Results: There is a substantial difference in performance between the scintillators depending on the imaging task but in general, the CsI based scintillators perform better than the Gadox scintillators. At low energies (16 keV), a thin needle CsI scintillator has the best performance at all frequencies. At higher energies (28–38 keV), the thicker needle CsI scintillators and the structured CsI scintillator all have very good performance. The needle CsI scintillators have higher absorption efficiencies but the structured CsI scintillator has higher resolution. Conclusions: The choice of scintillator is greatly dependent on the imaging task. The presented comparison and methodology will assist the imaging scientist in optimizing their high-resolution few-ten-keV imaging system for best performance.« less

Characterization of scintillator-based detectors for few-ten-keV high-spatial-resolution x-ray imaging.

PubMed

Larsson, Jakob C; Lundström, Ulf; Hertz, Hans M

2016-06-01

High-spatial-resolution x-ray imaging in the few-ten-keV range is becoming increasingly important in several applications, such as small-animal imaging and phase-contrast imaging. The detector properties critically influence the quality of such imaging. Here the authors present a quantitative comparison of scintillator-based detectors for this energy range and at high spatial frequencies. The authors determine the modulation transfer function, noise power spectrum (NPS), and detective quantum efficiency for Gadox, needle CsI, and structured CsI scintillators of different thicknesses and at different photon energies. An extended analysis of the NPS allows for direct measurements of the scintillator effective absorption efficiency and effective light yield as well as providing an alternative method to assess the underlying factors behind the detector properties. There is a substantial difference in performance between the scintillators depending on the imaging task but in general, the CsI based scintillators perform better than the Gadox scintillators. At low energies (16 keV), a thin needle CsI scintillator has the best performance at all frequencies. At higher energies (28-38 keV), the thicker needle CsI scintillators and the structured CsI scintillator all have very good performance. The needle CsI scintillators have higher absorption efficiencies but the structured CsI scintillator has higher resolution. The choice of scintillator is greatly dependent on the imaging task. The presented comparison and methodology will assist the imaging scientist in optimizing their high-resolution few-ten-keV imaging system for best performance.

Neutron/gamma pulse shape discrimination (PSD) in plastic scintillators with digital PSD electronics

NASA Astrophysics Data System (ADS)

Hutcheson, Anthony L.; Simonson, Duane L.; Christophersen, Marc; Phlips, Bernard F.; Charipar, Nicholas A.; Piqué, Alberto

2013-05-01

Pulse shape discrimination (PSD) is a common method to distinguish between pulses produced by gamma rays and neutrons in scintillator detectors. This technique takes advantage of the property of many scintillators that excitations by recoil protons and electrons produce pulses with different characteristic shapes. Unfortunately, many scintillating materials with good PSD properties have other, undesirable properties such as flammability, toxicity, low availability, high cost, and/or limited size. In contrast, plastic scintillator detectors are relatively low-cost, and easily handled and mass-produced. Recent studies have demonstrated efficient PSD in plastic scintillators using a high concentration of fluorescent dyes. To further investigate the PSD properties of such systems, mixed plastic scintillator samples were produced and tested. The addition of up to 30 wt. % diphenyloxazole (DPO) and other chromophores in polyvinyltoluene (PVT) results in efficient detection with commercial detectors. These plastic scintillators are produced in large diameters up to 4 inches by melt blending directly in a container suitable for in-line detector use. This allows recycling and reuse of materials while varying the compositions. This strategy also avoids additional sample handling and polishing steps required when using removable molds. In this presentation, results will be presented for different mixed-plastic compositions and compared with known scintillating materials

Investigation of depth-of-interaction (DOI) effects in single- and dual-layer block detectors by the use of light sharing in scintillators.

PubMed

Yamamoto, Seiichi

2012-01-01

In block detectors for PET scanners that use different lengths of slits in scintillators to share light among photomultiplier tubes (PMTs), a position histogram is distorted when the depth of interaction (DOI) of the gamma photons is near the PMTs (DOI effect). However, it remains unclear whether a DOI effect is observed for block detectors that use light sharing in scintillators. To investigate the effect, I tested the effect for single- and dual-layer block detectors. In the single-layer block detector, Ce doped Gd₂SiO₅ (GSO) crystals of 1.9 × 1.9 × 15 mm³ (0.5 mol% Ce) were used. In the dual-layer block detector, GSO crystals of a 1.9 × 1.9 × 6 mm³ (1.5 mol% Ce) were used for the front layer and GSO crystals of 1.9 × 1.9 × 9 mm³ (0.5 mol% Ce) for the back layer. These scintillators were arranged to form an 8 × 8 matrix with multi-layer optical film inserted partly between the scintillators for obtaining an optimized position response with use of two dual-PMTs. Position histograms and energy responses were measured for these block detectors at three different DOI positions, and the flood histograms were obtained. The results indicated that DOI effects are observed in both block detectors, but the dual-layer block showed more severe distortion in the position histogram as well as larger energy variations. We conclude that, in the block detectors that use light sharing in the scintillators, the DOI effect is an important factor for the performance of the detectors, especially for DOI block detectors.

Detector optimization for hand-held CsI(Tl)/HgI{sub 2} gamma-ray scintillation spectrometer applications

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

Wang, Y.J.; Patt, B.E.; Iwanczyk, J.S.

Gamma-ray spectrometers using mercuric iodide (HgI{sub 2}) photodetectors (PDs) coupled with CsI(Tl) scintillators have shown excellent energy resolutions and high detection efficiency at room temperature. Additionally HgI{sub 2} semiconductor PDs allow for extreme miniaturization of the detector packaging compared with photomultiplier tube (PMT) based detectors. These advantages make possible the construction of a new generation of hand-held gamma-ray spectrometers. Studies of detector optimization for this application have been undertaken. Several contact materials including hydrogen and semi-transparent metal films have been evaluated and compared for their performances and long term stability. In order to provide higher gamma-ray detection efficiency (i.e., largermore » scintillator volume), but without causing significant degradation of the excellent response achieved with the matched scintillator/PD interface, the scintillator/PD configuration has been studied. A Monte Carlo simulation model has been developed so that the spectral shape can be predicted for various scintillator shapes and surface treatments.« less

Linac based photofission inspection system employing novel detection concepts

NASA Astrophysics Data System (ADS)

Stevenson, John; Gozani, Tsahi; Elsalim, Mashal; Condron, Cathie; Brown, Craig

2011-10-01

Rapiscan Systems is developing a LINAC based cargo inspection system for detection of special nuclear material (SNM) in cargo containers. The system, called Photofission Based Alarm Resolution (PBAR) is being developed under a DHD/DNDO Advanced Technology Demonstration (ATD) program. The PBAR system is based on the Rapiscan Eagle P9000 X-ray system, which is a portal system with a commercial 9 MeV LINAC X-ray source. For the purposes of the DNDO ATD program, a conveyor system was installed in the portal to allow scanning and precise positioning of 20 ft ISO cargo containers. The system uses a two step inspection process. In the first step, the basic scan, the container is quickly and completely inspected using two independent radiography arrays: the conventional primary array with high spatial resolution and a lower resolution spectroscopic array employing the novel Z-Spec method. The primary array uses cadmium tungstate (CdWO 4) detectors with conventional current mode readouts using photodiodes. The Z-Spec array uses small plastic scintillators capable of performing very fast (up to 10 8 cps) gamma-ray spectroscopy. The two radiography arrays are used to locate high-Z objects in the image such as lead, tungsten, uranium, which could be potential shielding materials as well as SNM itself. In the current system, the Z-Spec works by measuring the energy spectrum of transmitted X-rays. For high-Z materials the higher end of the energy spectrum is more attenuated than for low-Z materials and thus has a lower mean energy and a narrower width than low- and medium-Z materials. The second step in the inspection process is the direct scan or alarm clearing scan. In this step, areas of the container image, which were identified as high Z, are re-inspected. This is done by precisely repositioning the container to the location of the high-Z object and performing a stationary irradiation of the area with X-ray beam. Since there are a large number of photons in the 9 MV Bremsstrahlung spectrum above the photofission "threshold" of about 6 MeV, the X-ray beam induces numerous fissions if nuclear material is present. The PBAR system looks for the two most prolific fission signatures to confirm the presence of special nuclear materials (SNM). These are prompt neutrons and delayed gamma rays. The PBAR system uses arrays of two types of fast and highly efficient gamma ray detectors: plastic and fluorocarbon scintillators. The latter serves as a detector of fission prompt neutrons using the novel threshold activation detector (TAD) concept as well as a very efficient delayed gamma ray detector. The major advantage of TAD for detecting the prompt neutrons is its insensitivity to the intense source related backgrounds. The current status of the system and experimental results will be shown and discussed.

Smaller, Lower-Power Fast-Neutron Scintillation Detectors

NASA Technical Reports Server (NTRS)

Patel, Jagdish; Blaes, Brent

2008-01-01

Scintillation-based fast-neutron detectors that are smaller and less power-hungry than mainstream scintillation-based fast-neutron detectors are undergoing development. There are numerous applications for such detectors in monitoring fast-neutron fluxes from nuclear reactors, nuclear materials, and natural sources, both on Earth and in outer space. A particularly important terrestrial application for small, low-power, portable fast-neutron detectors lies in the requirement to scan for nuclear materials in cargo and baggage arriving at international transportation facilities. The present development of miniature, low-power scintillation-based fast-neutron detectors exploits recent advances in the fabrication of avalanche photodiodes (APDs). Basically, such a detector includes a plastic scintillator, typically between 300 and 400 m thick with very thin silver mirror coating on all its faces except the one bonded to an APD. All photons generated from scintillation are thus internally reflected and eventually directed to the APD. This design affords not only compactness but also tight optical coupling for utilization of a relatively large proportion of the scintillation light. The combination of this tight coupling and the avalanche-multiplication gain (typically between 750 and 1,000) of the APD is expected to have enough sensitivity to enable monitoring of a fast-neutron flux as small as 1,000 cm(exp -2)s(exp -1). Moreover, pulse-height analysis can be expected to provide information on the kinetic energies of incident neutrons. It has been estimated that a complete, fully developed fast-neutron detector of this type, would be characterized by linear dimensions of the order of 10 cm or less, a mass of no more than about 0.5 kg, and a power demand of no more than a few watts.

Calculations and measurements of the scintillator-to-water stopping power ratio of liquid scintillators for use in proton radiotherapy

PubMed Central

Ingram, W. Scott; Robertson, Daniel; Beddar, Sam

2015-01-01

Liquid scintillators are a promising detector for high-resolution three-dimensional proton therapy dosimetry. Because the scintillator comprises both the active volume of the detector and the phantom material, an ideal scintillator will exhibit water equivalence in its radiological properties. One of the most fundamental of these is the scintillator’s stopping power. The objective of this study was to compare calculations and measurements of scintillator-to-water stopping power ratios to evaluate the suitability of the liquid scintillators BC-531 and OptiPhase HiSafe 3 for proton dosimetry. We also measured the relative scintillation output of the two scintillators. Both calculations and measurements show that the linear stopping power of OptiPhase is significantly closer to water than that of BC-531. BC-531 has a somewhat higher scintillation output. OptiPhase can be mixed with water at high concentrations, which further improves its scintillator-to-water stopping power ratio. However, this causes the solution to become cloudy, which has a negative impact on the scintillation output and spatial resolution of the detector. OptiPhase is preferred over BC-531 for proton dosimetry because its density and scintillator-to-water stopping power ratio are more water equivalent. PMID:25705066

Neutron detection with plastic scintillators coupled to solid state photomultiplier detectors

NASA Astrophysics Data System (ADS)

Christian, James F.; Johnson, Erik B.; Fernandez, Daniel E.; Vogel, Samuel; Frank, Rebecca; Stoddard, Graham; Stapels, Christopher; Pereira, Jorge; Zegers, Remco

2017-09-01

The recent reduction of dark current in Silicon Solid-state photomultipliers (SiSSPMs) makes them an attractive alternative to conventional photomultiplier tubes (PMTs) for scintillation detection applications. Nuclear Physics experiments often require large detector volumes made using scintillation materials, which require sensitive photodetectors, such as a PMTs. PMTs add to the size, fragility, and high-voltage requirements as well as distance requirements for experiments using magnetic fields. This work compares RMD's latest detector modules, denoted as the "year 2 prototype", of plastic scintillators that discriminate gamma and high-energy particle events from neutron events using pulse shape discrimination (PSD) coupled to a SiSSPM to the following two detector modules: a similar "year 1 prototype" and a scintillator coupled to a PMT module. It characterizes the noise floor, relative signal-to-noise ratio (SNR), the timing performance, the PSD figure-of-merit (FOM) and the neutron detection efficiency of RMD's detectors. This work also evaluates the scaling of SiSSPM detector modules to accommodate the volumes needed for many Nuclear Physics experiments. The Si SSPM detector module provides a clear advantage in Nuclear Physics experiments that require the following attributes: discrimination of neutron and gamma-ray events, operation in or near strong magnetic fields, and segmentation of the detector.

Method, apparatus and system for low-energy beta particle detection

DOEpatents

Akers, Douglas W.; Drigert, Mark W.

2012-09-25

An apparatus, method, and system relating to radiation detection of low-energy beta particles are disclosed. An embodiment includes a radiation detector with a first scintillator and a second scintillator operably coupled to each other. The first scintillator and the second scintillator are each structured to generate a light pulse responsive to interaction with beta particles. The first scintillator is structured to experience full energy deposition of low-energy beta particles, and permit a higher-energy beta particle to pass therethrough and interact with the second scintillator. The radiation detector further includes a light-to-electrical converter operably coupled to the second scintillator and configured to convert light pulses generated by the first scintillator and the second scintillator into electrical signals. The first scintillator and the second scintillator have at least one mutually different characteristic to enable an electronic system to determine whether a given light pulse is generated in the first scintillator or the second scintillator.

Compact, high-resolution, gamma ray imaging for scintimammography and other medical diagostic applications

DOEpatents

Majewski, Stanislaw; Weisenberger, Andrew G.; Wojcik, Randolph F.; Steinbach, Daniela

1999-01-01

A high resolution gamma ray imaging device includes an aluminum housing, a lead screen collimator at an opened end of the housing, a crystal scintillator array mounted behind the lead screen collimator, a foam layer between the lead screen collimator and the crystal scintillator array, a photomultiplier window coupled to the crystal with optical coupling grease, a photomultiplier having a dynode chain body and a base voltage divider with anodes, anode wire amplifiers each connected to four anodes and a multi pin connector having pin connections to each anode wire amplifier. In one embodiment the crystal scintillator array includes a yttrium aluminum perovskite (YAP) crystal array. In an alternate embodiment, the crystal scintillator array includes a gadolinium oxyorthosilicate (GSO) crystal array.

The Status and Recent Results of the Telescope Array Experiment

NASA Astrophysics Data System (ADS)

Yamazaki, Katsuya

The Telescope Array (TA) is a cosmic ray observatory of the largest aperture in the northern hemisphere, located in a desert in the western part of Utah, U.S.A., to explore the origin of ultrahigh energy cosmic rays, photons, and neutrinos. The TA employs two types of detectors to observe air showers generated by cosmic rays in the atmosphere: the first is a "surface detector (SD)" of scintillation counters to measure shower particles on the ground, and the second is a "fluorescence detector (FD)" of telescopes installed in three stations to observe fluorescence light, caused by air shower particles, from the atmosphere above the SD array. The TA detectors have been in routine operation since May 2008. We measured the energy spectrum of cosmic rays with energy greater than 1018 eV from our first 4-year data. We found a clear suppression of comic ray intensity above 5 × 1019 eV. This feature is consistent with a theoretical prediction that cosmic rays lose energies due to interaction with cosmic microwave background photons during propagation in the intergalactic space. In this talk, We will present the status of the TA experiment and the recent results, including the energy spectrum, study of the primary mass composition, and searches for anisotropies in the arrival directions. We also briefly describe plans for further extensions.

Optimum design calculations for detectors based on ZnSe(Те,О) scintillators

NASA Astrophysics Data System (ADS)

Katrunov, K.; Ryzhikov, V.; Gavrilyuk, V.; Naydenov, S.; Lysetska, O.; Litichevskyi, V.

2013-06-01

Light collection in scintillators ZnSe(X), where X is an isovalent dopant, was studied using Monte Carlo calculations. Optimum design was determined for detectors of "scintillator—Si-photodiode" type, which can involve either one scintillation element or scintillation layers of large area made of small-crystalline grains. The calculations were carried out both for determination of the optimum scintillator shape and for design optimization of light guides, on the surface of which the layer of small-crystalline grains is formed.

Three dimensional imaging detector employing wavelength-shifting optical fibers

DOEpatents

Worstell, William A.

1997-01-01

A novel detector element structure and method for its use is provided. In a preferred embodiment, one or more inorganic scintillating crystals are coupled through wavelength shifting optical fibers (WLSFs) to position sensitive photomultipliers (PS-PMTs). The superior detector configuration in accordance with this invention is designed for an array of applications in high spatial resolution gamma ray sensing with particular application to SPECT, PET and PVI imaging systems. The design provides better position resolution than prior art devices at a lower total cost. By employing wavelength shifting fibers (WLSFs), the sensor configuration of this invention can operate with a significant reduction in the number of photomultipliers and electronics channels, while potentially improving the resolution of the system by allowing three dimensional reconstruction of energy deposition positions.

Three dimensional imaging detector employing wavelength-shifting optical fibers

DOEpatents

Worstell, W.A.

1997-02-04

A novel detector element structure and method for its use is provided. In a preferred embodiment, one or more inorganic scintillating crystals are coupled through wavelength shifting optical fibers (WLSFs) to position sensitive photomultipliers (PS-PMTs). The superior detector configuration in accordance with this invention is designed for an array of applications in high spatial resolution gamma ray sensing with particular application to SPECT, PET and PVI imaging systems. The design provides better position resolution than prior art devices at a lower total cost. By employing wavelength shifting fibers (WLSFs), the sensor configuration of this invention can operate with a significant reduction in the number of photomultipliers and electronics channels, while potentially improving the resolution of the system by allowing three dimensional reconstruction of energy deposition positions. 11 figs.

Fast range measurement of spot scanning proton beams using a volumetric liquid scintillator detector.

PubMed

Hui, CheukKai; Robertson, Daniel; Alsanea, Fahed; Beddar, Sam

2015-08-01

Accurate confirmation and verification of the range of spot scanning proton beams is crucial for correct dose delivery. Current methods to measure proton beam range using ionization chambers are either time-consuming or result in measurements with poor spatial resolution. The large-volume liquid scintillator detector allows real-time measurements of the entire dose profile of a spot scanning proton beam. Thus, liquid scintillator detectors are an ideal tool for measuring the proton beam range for commissioning and quality assurance. However, optical artefacts may decrease the accuracy of measuring the proton beam range within the scintillator tank. The purpose of the current study was to 1) develop a geometric calibration system to accurately calculate physical distances within the liquid scintillator detector, taking into account optical artefacts; and 2) assess the accuracy, consistency, and robustness of proton beam range measurement using the liquid scintillator detector with our geometric calibration system. The range of the proton beam was measured with the calibrated liquid scintillator system and was compared to the nominal range. Measurements were made on three different days to evaluate the setup robustness from day to day, and three sets of measurements were made for each day to evaluate the consistency from delivery to delivery. All proton beam ranges measured using the liquid scintillator system were within half a millimeter of the nominal range. The delivery-to-delivery standard deviation of the range measurement was 0.04 mm, and the day-to-day standard deviation was 0.10 mm. In addition to the accuracy and robustness demonstrated by these results when our geometric calibration system was used, the liquid scintillator system allowed the range of all 94 proton beams to be measured in just two deliveries, making the liquid scintillator detector a perfect tool for range measurement of spot scanning proton beams.

Fast range measurement of spot scanning proton beams using a volumetric liquid scintillator detector

PubMed Central

Hui, CheukKai; Robertson, Daniel; Alsanea, Fahed; Beddar, Sam

2016-01-01

Accurate confirmation and verification of the range of spot scanning proton beams is crucial for correct dose delivery. Current methods to measure proton beam range using ionization chambers are either time-consuming or result in measurements with poor spatial resolution. The large-volume liquid scintillator detector allows real-time measurements of the entire dose profile of a spot scanning proton beam. Thus, liquid scintillator detectors are an ideal tool for measuring the proton beam range for commissioning and quality assurance. However, optical artefacts may decrease the accuracy of measuring the proton beam range within the scintillator tank. The purpose of the current study was to 1) develop a geometric calibration system to accurately calculate physical distances within the liquid scintillator detector, taking into account optical artefacts; and 2) assess the accuracy, consistency, and robustness of proton beam range measurement using the liquid scintillator detector with our geometric calibration system. The range of the proton beam was measured with the calibrated liquid scintillator system and was compared to the nominal range. Measurements were made on three different days to evaluate the setup robustness from day to day, and three sets of measurements were made for each day to evaluate the consistency from delivery to delivery. All proton beam ranges measured using the liquid scintillator system were within half a millimeter of the nominal range. The delivery-to-delivery standard deviation of the range measurement was 0.04 mm, and the day-to-day standard deviation was 0.10 mm. In addition to the accuracy and robustness demonstrated by these results when our geometric calibration system was used, the liquid scintillator system allowed the range of all 94 proton beams to be measured in just two deliveries, making the liquid scintillator detector a perfect tool for range measurement of spot scanning proton beams. PMID:27274863

VECC array for Nuclear fast Timing and angUlar corRElation studies (VENTURE)

NASA Astrophysics Data System (ADS)

Alam, S. S.; Bhattacharjee, T.; Banerjee, D.; Saha, A.; Pandit, Deepak; Mondal, D.; Mukhopadhyay, S.; Pal, Surajit; Bhaskar, P.; Das, S. K.; Banerjee, S. R.

2017-12-01

The VECC array for Nuclear fast Timing and angUlar corRElation studies (VENTURE) has been developed using several fast Cerium-Bromide (CeBr3) scintillators coupled to Hamamatsu R9779 Photomultiplier tubes. The CeBr3 detector has been characterised for the spectroscopic properties like energy response, energy resolution, timing resolution and detection efficiency. The response and efficiency of the detector have been compared with the results obtained from a Monte Carlo simulation with GEANT3 package. A time resolution of 144(1) ps and 109(1) ps was obtained for a single detector using 622-512 keV and 1173-1332 keV cascades respectively. The Generalised Centroid Difference (GCD) method has been employed with CeBr3 detectors by measuring the level lifetimes for the 511.9 keV level of 106Pd and the 160.6 and 383.8 keV levels of 133Cs. The angular correlation measurement was performed for the 1173-1332 keV cascade in 60Ni and the 228-49 keV cascade of 132I nucleus, populated from the decay of 132Te produced via 238U(α, f) reaction.

Measurement of the absolute reflectance of polytetrafluoroethylene (PTFE) immersed in liquid xenon

NASA Astrophysics Data System (ADS)

Neves, F.; Lindote, A.; Morozov, A.; Solovov, V.; Silva, C.; Bras, P.; Rodrigues, J. P.; Lopes, M. I.

2017-01-01

The performance of a detector using liquid xenon (LXe) as a scintillator is strongly dependent on the collection efficiency for xenon scintillation light, which in turn is critically dependent on the reflectance of the surfaces that surround the active volume. To improve the light collection in such detectors the active volume is usually surrounded by polytetrafluoroethylene (PTFE) reflector panels, used due to its very high reflectance—even at the short wavelength of scintillation light of LXe (peaked at 178 nm). In this work, which contributed to the overall R&D effort towards the LUX-ZEPLIN (LZ) experiment, we present experimental results for the absolute reflectance measurements of three different PTFE samples (including the material used in the LUX detector) immersed in LXe for its scintillation light. The obtained results show that very high bi-hemispherical reflectance values (>= 97%) can be achieved, enabling very low energy thresholds in liquid xenon scintillator-based detectors.

Rejection of Alpha Surface Background in Non-scintillating Bolometric Detectors: The ABSuRD Project

DOE PAGES

Biassoni, M.; Brofferio, C.; Bucci, C.; ...

2016-01-14

Due to their excellent energy resolution values and the vast choice of possible materials, bolometric detectors are currently widely used in the physics of rare events. A limiting aspect for bolometers rises from their inability to discriminate among radiation types or surface from bulk events. It has been demonstrated that the main limitation to sensitivity for purely bolometric detectors is represented by surface alpha contaminations, causing a continuous background that cannot be discriminated. A new scintillation based technique for the rejection of surface alpha background in non- scintillating bolometric experiments is proposed in this work. The idea is to combinemore » a scintillating and a high sensitivity photon detector with a non- scintillating absorber. Finally, we present results showing the possibility to reject events due to alpha decay at or nearby the surface of the crystal.« less

Development of a Compton camera for medical applications based on silicon strip and scintillation detectors

NASA Astrophysics Data System (ADS)

Krimmer, J.; Ley, J.-L.; Abellan, C.; Cachemiche, J.-P.; Caponetto, L.; Chen, X.; Dahoumane, M.; Dauvergne, D.; Freud, N.; Joly, B.; Lambert, D.; Lestand, L.; Létang, J. M.; Magne, M.; Mathez, H.; Maxim, V.; Montarou, G.; Morel, C.; Pinto, M.; Ray, C.; Reithinger, V.; Testa, E.; Zoccarato, Y.

2015-07-01

A Compton camera is being developed for the purpose of ion-range monitoring during hadrontherapy via the detection of prompt-gamma rays. The system consists of a scintillating fiber beam tagging hodoscope, a stack of double sided silicon strip detectors (90×90×2 mm3, 2×64 strips) as scatter detectors, as well as bismuth germanate (BGO) scintillation detectors (38×35×30 mm3, 100 blocks) as absorbers. The individual components will be described, together with the status of their characterization.

Use and imaging performance of CMOS flat panel imager with LiF/ZnS(Ag) and Gadox scintillation screens for neutron radiography

NASA Astrophysics Data System (ADS)

Cha, B. K.; kim, J. Y.; Kim, T. J.; Sim, C.; Cho, G.; Lee, D. H.; Seo, C.-W.; Jeon, S.; Huh, Y.

2011-01-01

In digital neutron radiography system, a thermal neutron imaging detector based on neutron-sensitive scintillating screens with CMOS(complementary metal oxide semiconductor) flat panel imager is introduced for non-destructive testing (NDT) application. Recently, large area CMOS APS (active-pixel sensor) in conjunction with scintillation films has been widely used in many digital X-ray imaging applications. Instead of typical imaging detectors such as image plates, cooled-CCD cameras and amorphous silicon flat panel detectors in combination with scintillation screens, we tried to apply a scintillator-based CMOS APS to neutron imaging detection systems for high resolution neutron radiography. In this work, two major Gd2O2S:Tb and 6LiF/ZnS:Ag scintillation screens with various thickness were fabricated by a screen printing method. These neutron converter screens consist of a dispersion of Gd2O2S:Tb and 6LiF/ZnS:Ag scintillating particles in acrylic binder. These scintillating screens coupled-CMOS flat panel imager with 25x50mm2 active area and 48μm pixel pitch was used for neutron radiography. Thermal neutron flux with 6x106n/cm2/s was utilized at the NRF facility of HANARO in KAERI. The neutron imaging characterization of the used detector was investigated in terms of relative light output, linearity and spatial resolution in detail. The experimental results of scintillating screen-based CMOS flat panel detectors demonstrate possibility of high sensitive and high spatial resolution imaging in neutron radiography system.

Development of a thin scintillation films fission-fragment detector and a novel neutron source

DOE PAGES

Rusev, Gencho Yordanov; Jandel, Marian; Baramsai, Bayarbadrakh; ...

2015-08-26

Here, investigation of prompt fission and neutron-capture Υ rays from fissile actinide samples at the Detector for Advanced Neutron Capture Experiments (DANCE) requires use of a fission-fragment detector to provide a trigger or a veto signal. A fission-fragment detector based on thin scintillating films and silicon photomultipliers has been built to serve as a trigger/veto detector in neutron-induced fission measurements at DANCE. The fissile material is surrounded by scintillating films providing a 4π detection of the fission fragments. The scintillations were registered with silicon photomultipliers. A measurement of the 235U(n,f) reaction with this detector at DANCE revealed a correct time-of-flightmore » spectrum and provided an estimate for the efficiency of the prototype detector of 11.6(7)%. Design and test measurements with the detector are described. A neutron source with fast timing has been built to help with detector-response measurements. The source is based on the neutron emission from the spontaneous fission of 252Cf and the same type of scintillating films and silicon photomultipliers. Overall time resolution of the source is 0.3 ns. Design of the source and test measurements with it are described. An example application of the source for determining the neutron/gamma pulse-shape discrimination by a stilbene crystal is given.« less

Characterization of a 2 × 2 array of large square bars of LaBr3:Ce detectors with γ-rays up to 22.5 MeV

NASA Astrophysics Data System (ADS)

Dhibar, M.; Mazumdar, I.; Chavan, P. B.; Patel, S. M.; Anil Kumar, G.

2018-03-01

LaBr3:Ce scintillators have recently become commercially available in sizes large enough for measurements of high energy gamma-rays. In this communication, we report our studies on properties and response of large volume square bars (2‧‧ ×2‧‧ ×8‧‧) of LaBr3:Ce detectors, individually, and in a compact array of four square bars, with gamma-rays up to 22.5 MeV. The properties studied are, uniformity of the crystal, internal radioactivity, energy resolution, timing resolution, linearity of the response and detection efficiencies. The response of the detectors for 22.5 MeV γ-rays produced from 11B(p , γ)12C capture reaction and for 15.1 MeV γ-rays produced from 12C(p ,p‧ γ)12C inelastic scattering reaction are studied in detail. The measured absolute efficiencies (both total detection and photo-peak) for 662 keV gamma-rays from 137Cs are compared to those obtained using realistic GEANT4 simulations. The primary aim of the array is to measure high energy gamma-rays (5-50 MeV) produced from the de-excitation of excited Giant Dipole Resonance (GDR) states, radiative capture reactions, nuclear Bremsstrahlung process and inelastic scattering process. The highly satisfactory performance of the array provides the impetus for future efforts toward building a bigger array.

Principal Component Analysis for pulse-shape discrimination of scintillation radiation detectors

NASA Astrophysics Data System (ADS)

Alharbi, T.

2016-01-01

In this paper, we report on the application of Principal Component analysis (PCA) for pulse-shape discrimination (PSD) of scintillation radiation detectors. The details of the method are described and the performance of the method is experimentally examined by discriminating between neutrons and gamma-rays with a liquid scintillation detector in a mixed radiation field. The performance of the method is also compared against that of the conventional charge-comparison method, demonstrating the superior performance of the method particularly at low light output range. PCA analysis has the important advantage of automatic extraction of the pulse-shape characteristics which makes the PSD method directly applicable to various scintillation detectors without the need for the adjustment of a PSD parameter.

BNLs Synchrotron-radiation Research Hub for Characterizing Detection Materials and Devices for the NA-22 Community

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

Camarda, G. S.; Bolotnikov, A. E.; Cui, Y.

The goal of this project is to obtain and characterize scintillators, emerging- and commercial-compoundsemiconductor radiation- detection materials and devices provided by vendors and research organizations. The focus of our proposed research is to clarify the role of the deleterious defects and impurities responsible for the detectors' non-uniformity in scintillating crystals, commercial semiconductor radiation-detector materials, and in emerging R&D ones. Some benefits of this project addresses the need for fabricating high-performance scintillators and compound-semiconductor radiation-detectors with the proven potential for large-scale manufacturing. The findings help researchers to resolve the problems of non-uniformities in scintillating crystals, commercial semiconductor radiation-detector materials, and inmore » emerging R&D ones.« less

Effects of reflector and crystal surface on the performance of a depth-encoding PET detector with dual-ended readout

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

Ren, Silin; Yang, Yongfeng, E-mail: yfyang@ucdavis.edu; Cherry, Simon R.

Purpose: Depth encoding detectors are required to improve the spatial resolution and spatial resolution uniformity of small animal positron emission tomography (PET) scanners, as well as dedicated breast and brain scanners. Depth of interaction (DOI) can be measured by using dual-ended readout of lutetium oxyorthosilicate (LSO) scintillator arrays with position-sensitive avalanche photodiodes. Inter-crystal reflectors and crystal surface treatments play important roles in determining the performance of dual-ended detectors. In this paper, the authors evaluated five LSO arrays made with three different intercrystal reflectors and with either polished or unpolished crystal surfaces. Methods: The crystal size in all arrays was 1.5more » mm, which is typical of the detector size used in small animal and dedicated breast scanners. The LSO arrays were measured with dual-ended readout and were compared in terms of flood histogram, energy resolution, and DOI resolution performance. Results: The four arrays using enhanced specular reflector (ESR) and Toray reflector provided similar quality flood histograms and the array using Crystal Wrap reflector gave the worst flood histogram. The two arrays using ESR reflector provided the best energy resolution and the array using Crystal Wrap reflector yielded the worst energy resolution. All arrays except the polished ESR array provided good DOI resolution ranging from 1.9 mm to 2.9 mm. DOI resolution improved as the gradient in light collection efficiency with depth (GLCED) increased. The geometric mean energies were also calculated for these dual-ended readout detectors as an alternative to the conventional summed total energy. It was shown that the geometric mean energy is advantageous in that it provides more uniform photopeak amplitude at different depths for arrays with high GLCED, and is beneficial in event selection by allowing a fixed energy window independent of depth. A new method of DOI calculation that improved the linearity of DOI ratio vs depth and simplifies the DOI calibration procedure also was developed and tested. Conclusions: The results of these studies provide useful guidance in selecting the proper reflectors and crystal surface treatments when LSO arrays are used for high-resolution PET applications in small animal scanners or dedicated breast and brain scanners.« less

The MONDO project: A secondary neutron tracker detector for particle therapy

NASA Astrophysics Data System (ADS)

Valle, S. M.; Battistoni, G.; Patera, V.; Pinci, D.; Sarti, A.; Sciubba, A.; Spiriti, E.; Marafini, M.

2017-02-01

During Particle Therapy treatments the patient irradiation produces, among different types of secondary radiation, an abundant flux of neutrons that can release a significant dose far away from the tumour region. A precise measurement of their flux, energy and angle distributions is eagerly needed in order to improve the Treatment Planning Systems software and to properly take into account the risk of late complications in the whole body. The technical challenges posed by a neutron detector aiming for high detection efficiency and good backtracking precision will be addressed within the MONDO project, whose main goal is to develop a tracking detector targeting fast and ultra-fast secondary neutrons. The neutron tracking principle is based on the reconstruction of two consequent elastic scattering interactions of a neutron with a target material. Reconstructing the recoiling protons it is hence possible to measure the energy and incoming direction of the neutron. Plastic scintillators will be used as scattering and detection media: the tracker is being developed as a matrix of squared scintillating fibres of 250 μm side. The light produced and collected in fibres will be amplified using a triple GEM-based image intensifier and acquired using CMOS Single Photon Avalanche Diode arrays. Using therapeutic beams, the principal detector goal will be the measurement of the neutron production yields, as a function of production angle and energy.

An experiment to study the nuclear component of primary cosmic rays

NASA Technical Reports Server (NTRS)

Paul, J. M.; Verma, S. D.

1971-01-01

An apparatus has been designed and is being fabricated to study the charge composition, fluxes, and energy spectra of light nuclei in the energy region from 1 GeV to 100 GeV. The apparatus essentially consists of an array of a large number of particle detectors operated in coincidence and serving as a charged particle telescope. A mosaic silicon semiconductor detector, a plastic scintillation counter and a lucite Cerenkov detector are used to measure the charges of the incident nuclei. Two one-inch thick CsI detectors are used to study low energy particles. An ionization spectrometer is utilized to measure primary energies in the 1 to 100 GeV energy interval. A gas Cerenkov counter is being designed to distinguish between electrons and protons. It is planned to calibrate the apparatus at an accelerator using particles of known energy.

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

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

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

First array of enriched Zn$$^{82}$$Se bolometers to search for double beta decay

DOE PAGES

Artusa, D. R.; Balzoni, A.; Beeman, J. W.; ...

2016-07-01

The R&D activity performed during the last years proved the potential of ZnSe scintillating bolometers to the search for neutrino-less double beta decay, motivating the realization of the first large-mass experiment based on this technology: CUPID-0. The isotopic enrichment in 82Se, the Zn 82Se crystals growth, as well as the light detectors production have been accomplished, and the experiment is now in construction at Laboratori Nazionali del Gran Sasso (Italy). In this paper we present the results obtained testing the first three Zn 82Se crystals operated as scintillating bolometers, and we prove that their performance in terms of energy resolution,more » background rejection capability and intrinsic radio-purity complies with the requirements of CUPID-o.« less

Simultaneous acquisition of multislice PET and MR images: initial results with a MR-compatible PET scanner.

PubMed

Catana, Ciprian; Wu, Yibao; Judenhofer, Martin S; Qi, Jinyi; Pichler, Bernd J; Cherry, Simon R

2006-12-01

PET and MRI are powerful imaging techniques that are largely complementary in the information they provide. We have designed and built a MR-compatible PET scanner based on avalanche photodiode technology that allows simultaneous acquisition of PET and MR images in small animals. The PET scanner insert uses magnetic field-insensitive, position-sensitive avalanche photodiode (PSAPD) detectors coupled, via short lengths of optical fibers, to arrays of lutetium oxyorthosilicate (LSO) scintillator crystals. The optical fibers are used to minimize electromagnetic interference between the radiofrequency and gradient coils and the PET detector system. The PET detector module components and the complete PET insert assembly are described. PET data were acquired with and without MR sequences running, and detector flood histograms were compared with the ones generated from the data acquired outside the magnet. A uniform MR phantom was also imaged to assess the effect of the PET detector on the MR data acquisition. Simultaneous PET and MRI studies of a mouse were performed ex vivo. PSAPDs can be successfully used to read out large numbers of scintillator crystals coupled through optical fibers with acceptable performance in terms of energy and timing resolution and crystal identification. The PSAPD-LSO detector performs well in the 7-T magnet, and no visible artifacts are detected in the MR images using standard pulse sequences. The first images from the complete system have been successfully acquired and reconstructed, demonstrating that simultaneous PET and MRI studies are feasible and opening up interesting possibilities for dual-modality molecular imaging studies.

NaI(Tl) scintillator read out with SiPM array for gamma spectrometer

NASA Astrophysics Data System (ADS)

Huang, Tuchen; Fu, Qibin; Lin, Shaopeng; Wang, Biao

2017-04-01

The NaI(Tl) scintillator is widely used in gamma spectrometer with photomultiplier tube (PMT) readout. Recently developed silicon photomultiplier (SiPM) offers gain and efficiency similar to those of PMT, but with merits such as low bias voltage, compact volume, low cost, high ruggedness and magnetic resonance compatibility. In this study, 2-in. and 1-in. NaI(Tl) scintillators were readout with SiPM arrays, which were made by tiling multiple SiPMs each with an active area of 6×6 mm2 on a printed circuit board. The energy resolutions for 661.6 keV gamma rays, obtained with Φ2×2 in. scintillator coupled to 6×6 ch SiPM array and Φ1×1 in. scintillator coupled to 4×4 ch SiPM array were 7.6% and 7.8%, respectively, and were very close to the results obtained with traditional bialkali PMT (7.3% and 7.6%, respectively). Scintillator coupled to photodetector with smaller area was also studied by adding a light guide or using scintillator with tapered head. The latter showed better performance than using light guide. The 1-in. NaI(Tl) scintillator with tapered head coupled to 2×2 ch SiPM array achieved 7.7% energy resolution at 661.6 keV, the same as that obtained with standard Φ1×1 in. scintillator coupled to 4×4 ch SiPM array. While the 2-in. scintillator with similar geometry showed degraded energy resolution, 10.2% at 661.6 keV, but could still be used when high efficiency is preferred over energy resolution.

Design, optimization and evaluation of a "smart" pixel sensor array for low-dose digital radiography

NASA Astrophysics Data System (ADS)

Wang, Kai; Liu, Xinghui; Ou, Hai; Chen, Jun

2016-04-01

Amorphous silicon (a-Si:H) thin-film transistors (TFTs) have been widely used to build flat-panel X-ray detectors for digital radiography (DR). As the demand for low-dose X-ray imaging grows, a detector with high signal-to-noise-ratio (SNR) pixel architecture emerges. "Smart" pixel is intended to use a dual-gate photosensitive TFT for sensing, storage, and switch. It differs from a conventional passive pixel sensor (PPS) and active pixel sensor (APS) in that all these three functions are combined into one device instead of three separate units in a pixel. Thus, it is expected to have high fill factor and high spatial resolution. In addition, it utilizes the amplification effect of the dual-gate photosensitive TFT to form a one-transistor APS that leads to a potentially high SNR. This paper addresses the design, optimization and evaluation of the smart pixel sensor and array for low-dose DR. We will design and optimize the smart pixel from the scintillator to TFT levels and validate it through optical and electrical simulation and experiments of a 4x4 sensor array.

BC404 scintillators as gamma locators studied via Geant4 simulations

NASA Astrophysics Data System (ADS)

Cortés, M. L.; Hoischen, R.; Eisenhauer, K.; Gerl, J.; Pietralla, N.

2014-05-01

In many applications in industry and academia, an accurate determination of the direction from where gamma rays are emitted is either needed or desirable. Ion-beam therapy treatments, the search for orphan sources, and homeland security applications are examples of fields that can benefit from directional sensitivity to gamma-radiation. Scintillation detectors are a good option for these types of applications as they have relatively low cost, are easy to handle and can be produced in a large range of different sizes. In this work a Geant4 simulation was developed to study the directional sensitivity of different BC404 scintillator geometries and arrangements. The simulation includes all the physical processes relevant for gamma detection in a scintillator. In particular, the creation and propagation of optical photons inside the scintillator was included. A simplified photomultiplier tube model was also simulated. The physical principle exploited is the angular dependence of the shape of the energy spectrum obtained from thin scintillator layers when irradiated from different angles. After an experimental confirmation of the working principle of the device and a check of the simulation, the possibilities and limitations of directional sensitivity to gamma radiation using scintillator layers was tested. For this purpose, point-like sources of typical energies expected in ion-beam therapy were used. Optimal scintillator thicknesses for different energies were determined and the setup efficiencies calculated. The use of arrays of scintillators to reconstruct the direction of incoming gamma rays was also studied. For this case, a spherical source emitting Bremsstrahlung radiation was used together with a setup consisting of scintillator layers. The capability of this setup to identify the center of the extended source was studied together with its angular resolution.

Optical Design Considerations for Efficient Light Collection from Liquid Scintillation Counters

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

Bernacki, Bruce E.; Douglas, Matthew; Erchinger, Jennifer L.

2015-01-01

Liquid scintillation counters measure charged particle-emitting radioactive isotopes and are used for environmental studies, nuclear chemistry, and life science. Alpha and beta emissions arising from the material under study interact with the scintillation cocktail to produce light. The prototypical liquid scintillation counter employs low-level photon-counting detectors to measure the arrival of the scintillation light produced as a result of the dissolved material under study interacting with the scintillation cocktail. For reliable operation the counting instrument must convey the scintillation light to the detectors efficiently and predictably. Current best practices employ the use of two or more detectors for coincidence processingmore » to discriminate true scintillation events from background events due to instrumental effects such as photomultiplier tube dark rates, tube flashing, or other light emission not generated in the scintillation cocktail vial. In low background liquid scintillation counters additional attention is paid to shielding the scintillation cocktail from naturally occurring radioactive material (NORM) present in the laboratory and within the instruments construction materials. Low background design is generally at odds with optimal light collection. This study presents the evolution of a light collection design for liquid scintillation counting in a low background shield. The basic approach to achieve both good light collection and a low background measurement is described. The baseline signals arising from the scintillation vial are modeled and methods to efficiently collect scintillation light are presented as part of the development of a customized low-background, high sensitivity liquid scintillation counting system.« less

Energy-resolved fast neutron resonance radiography at CSNS

NASA Astrophysics Data System (ADS)

Tan, Zhixin; Tang, Jingyu; Jing, Hantao; Fan, Ruirui; Li, Qiang; Ning, Changjun; Bao, Jie; Ruan, Xichao; Luan, Guangyuan; Feng, Changqin; Zhang, Xianpeng

2018-05-01

The white neutron beamline at the China Spallation Neutron Source will be used mainly for nuclear data measurements. It will be characterized by high flux and broad energy spectra. To exploit the beamline as a neutron imaging source, we propose a liquid scintillator fiber array for fast neutron resonance radiography. The fiber detector unit has a small exposed area, which will limit the event counts and separate the events in time, thus satisfying the requirements for single-event time-of-flight (SEToF) measurement. The current study addresses the physical design criteria for ToF measurement, including flux estimation and detector response. Future development and potential application of the technology are also discussed.

Radiation effects on ALICE V0 detector components

NASA Astrophysics Data System (ADS)

Cheynis, B.; Ducroux, L.; Grossiord, J.-Y.; Guichard, A.; Pillot, P.; Rapp, B.; Tieulent, R.; Tromeur, W.; Zoccarato, Y.

2006-12-01

The 60 MeV proton beam delivered by the RADEF facility of the University of Jyväskylä (Finland) was used to measure the radiation effects on the counter components of the V0 detector of ALICE. There are the scintillator BC404, the wavelength shifting fibres BCF9929A and the optical fibres BCF98 from Bicron (Saint-Gobain). The light yield and the time resolution given by a counter of the inner ring of the V0C array, mounted within a dedicated device, were measured as a function of the radiation dose up to about 300 krad. A global light attenuation of the order of 30% can be anticipated during 10 years of ALICE running.

Time correlated measurements using plastic scintillators with neutron-photon pulse shape discrimination

NASA Astrophysics Data System (ADS)

Richardson, Norman E., IV

Since the beginning of the nuclear age, there has been a strong demand for the development of efficient technologies for the detection of ionizing radiation. According to the United States' Department of Energy, the accurate assessment of fissile materials is essential in achieving the nonproliferation goals of enhancing safety and security of nuclear fuel cycle and nuclear energy facilities. Nuclear materials can be characterized by the measurement of prompt and delayed neutrons and gamma rays emitted in spontaneous or induced fission reactions and neutrons emitted in fission reactions are the distinctive signatures of nuclear materials. Today, the most widely used neutron detection technologies rely on thermal neutron capture reactions using a moderating material to cause the neutron to lose its energy prior to the detection event. This is necessary because as the fission event occurs, neutrons are emitted carrying high amounts of energy, typically on the order of mega electron volts (MeV). These energetic particles are classified as "fast" neutrons. For detecting the thermal neutrons, the Helium-3 (3He) gas-filled counters are arguably the most widely used technology of neutron detection. 3He counters have been the scientific standard for the nuclear engineering community for several decades, and have earned their place as a reliable technique for the detection of neutrons. However, 3He gas-filled counters have several disadvantages. First, gas-filled counters are not rigid and are sensitive to vibrations. Secondly, gas-filled counters are prone to the count rate limitations due to the physical processes of charge multiplication and transport in the gas medium in the electric field. Lastly, 3He gas-filled counters suffer from a supply shortage of the 3He isotope. As it is stated in [3], this shortage is created by the new demand for Helium-3 due to the deployment of neutron detectors at the borders after the 9/11 attack to help secure the nation against smuggled nuclear and radiological material. Moreover, the production of 3He isotope as a byproduct of security programs was drastically decreased. This isotope shortage coupled with the disadvantages of relying on a detector that requires neutron moderation before the detection of fission neutrons, poses a significant challenge in supporting the existing detection systems and the development of future technologies. To address this problem, a reliable and accurate alternative technology to detect neutrons emitted in fissions must be developed. One such alternative technology that shows promise in this application is the use of scintillators based on solid state materials (plastics) which are sensitive to fast neutrons. However, plastic scintillators are also sensitive to photons. Hence, it is necessary to separate the neutron signals from the photon signals, using the pulse shape discrimination (PSD) analysis. The PSD is based on the comparison of the pulse shapes of digitized signal waveforms. This approach allows for the measurement of fast neutrons without the necessity of their moderation. Because the fission spectrum neutrons are mainly fast, methods employing fast neutron detection are applicable for the assay of fissile materials. In addition, the average time of scintillation of the plastic medium is much shorter than those of the gaseous counters, thus allowing scintillation detectors to be used in high count rate environments. Furthermore, the temporal information of the fast neutron detection using multiple sensors enables the time correlation analysis of the fission neutron multiplicity. The study of time correlation measurements of fast neutrons using the array of plastic scintillators is the basis of this work. The array of four plastic scintillator detectors equipped with the digital data acquisition and analysis system was developed. The digital PSD analysis of detector signals "on-the-fly" was implemented for the array. The time coincidence measurement technique using the list mode was employed for two detectors operating on the single time scale. This was necessary as no fission source was available to be used as a fast neutron multiplicity source. The detection technology was tested using isotopic photon sources and a plutonium-beryllium neutron source. It was shown that the system can be effectively used for fast-neutron multiplicity measurements, through a "proof-of-concept" model, enabling a shorter width of the time coincidence window compared to the 3He counters. This result opens prospects to reduce the false coincidence rates in the neutron multiplicity measurements, thus increasing the sensitivity of nuclear material detection.

Design and evaluation of a SiPM-based large-area detector module for positron emission imaging

NASA Astrophysics Data System (ADS)

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

2018-03-01

The design and evaluation of a large-area detector module for positron emission imaging applications, is presented. The module features a SensL ArrayC-60035-64P-PCB solid state detector (8×8 array of tileable silicon photomultipliers by SensL, 7.2 mm pitch) covering a total area of 57.4×57.4 mm2. The detector module was formed using a pixelated array of 40×40 lutetium-yttrium oxyorthosilicate (LYSO) scintillator crystal elements with 1.43 mm pitch. A 7 mm thick coupling light guide was used to allow light sharing between adjacent SiPM. A 16-channel symmetric charge division (SCD) readout board was designed to multiplex the number of signals from 64 to 16 (8 columns and 8 rows) and a center-of-gravity algorithm to identify the position. Data acquisition and digitization was accomplished using a custom-made system based on FPGAs boards. Crystal maps were obtained using 18F-positron sources and Voronoi diagrams were used to correct for geometric distortions and to generate a non-uniformity correction matrix. All measurements were taken at a controlled room temperature of 22oC. The crystal maps showed minor distortion, 90% of the 1600 total crystal elements could be identified, a mean peak-to-valley ratio of 4.3 was obtained and a 10.8% mean energy resolution for 511 keV annihilation photons was determined. The performance of the detector using our own readout board was compared to that using two different commercially readout boards using the same detector module arrangement. We show that these large-area SiPM arrays, combined with a 16-channel SCD readout board, can offer high spatial resolution, excellent energy resolution and detector uniformity and thus, can be used for positron emission imaging applications.

Monte Carlo code G3sim for simulation of plastic scintillator detectors with wavelength shifter fiber readout.

PubMed

Mohanty, P K; Dugad, S R; Gupta, S K

2012-04-01

A detailed description of a compact Monte Carlo simulation code "G3sim" for studying the performance of a plastic scintillator detector with wavelength shifter (WLS) fiber readout is presented. G3sim was developed for optimizing the design of new scintillator detectors used in the GRAPES-3 extensive air shower experiment. Propagation of the blue photons produced by the passage of relativistic charged particles in the scintillator is treated by incorporating the absorption, total internal, and diffuse reflections. Capture of blue photons by the WLS fibers and subsequent re-emission of longer wavelength green photons is appropriately treated. The trapping and propagation of green photons inside the WLS fiber is treated using the laws of optics for meridional and skew rays. Propagation time of each photon is taken into account for the generation of the electrical signal at the photomultiplier. A comparison of the results from G3sim with the performance of a prototype scintillator detector showed an excellent agreement between the simulated and measured properties. The simulation results can be parametrized in terms of exponential functions providing a deeper insight into the functioning of these versatile detectors. G3sim can be used to aid the design and optimize the performance of scintillator detectors prior to actual fabrication that may result in a considerable saving of time, labor, and money spent. © 2012 American Institute of Physics

Compendium of Instrumentation Whitepapers on Frontier Physics Needs for Snowmass 2013

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

Lipton, R.

2013-01-01

Contents of collection of whitepapers include: Operation of Collider Experiments at High Luminosity; Level 1 Track Triggers at HL-LHC; Tracking and Vertex Detectors for a Muon Collider; Triggers for hadron colliders at the energy frontier; ATLAS Upgrade Instrumentation; Instrumentation for the Energy Frontier; Particle Flow Calorimetry for CMS; Noble Liquid Calorimeters; Hadronic dual-readout calorimetry for high energy colliders; Another Detector for the International Linear Collider; e+e- Linear Colliders Detector Requirements and Limitations; Electromagnetic Calorimetry in Project X Experiments The Project X Physics Study; Intensity Frontier Instrumentation; Project X Physics Study Calorimetry Report; Project X Physics Study Tracking Report; The LHCbmore » Upgrade; Neutrino Detectors Working Group Summary; Advanced Water Cherenkov R&D for WATCHMAN; Liquid Argon Time Projection Chamber (LArTPC); Liquid Scintillator Instrumentation for Physics Frontiers; A readout architecture for 100,000 pixel Microwave Kinetic In- ductance Detector array; Instrumentation for New Measurements of the Cosmic Microwave Background polarization; Future Atmospheric and Water Cherenkov ?-ray Detectors; Dark Energy; Can Columnar Recombination Provide Directional Sensitivity in WIMP Search?; Instrumentation Needs for Detection of Ultra-high Energy Neu- trinos; Low Background Materials for Direct Detection of Dark Matter; Physics Motivation for WIMP Dark Matter Directional Detection; Solid Xenon R&D at Fermilab; Ultra High Energy Neutrinos; Instrumentation Frontier: Direct Detection of WIMPs; nEXO detector R&D; Large Arrays of Air Cherenkov Detectors; and Applications of Laser Interferometry in Fundamental Physics Experiments.« less

A Prototype High-Resolution Small-Animal PET Scanner Dedicated to Mouse Brain Imaging.

PubMed

Yang, Yongfeng; Bec, Julien; Zhou, Jian; Zhang, Mengxi; Judenhofer, Martin S; Bai, Xiaowei; Di, Kun; Wu, Yibao; Rodriguez, Mercedes; Dokhale, Purushottam; Shah, Kanai S; Farrell, Richard; Qi, Jinyi; Cherry, Simon R

2016-07-01

We developed a prototype small-animal PET scanner based on depth-encoding detectors using dual-ended readout of small scintillator elements to produce high and uniform spatial resolution suitable for imaging the mouse brain. The scanner consists of 16 tapered dual-ended-readout detectors arranged in a 61-mm-diameter ring. The axial field of view (FOV) is 7 mm, and the transaxial FOV is 30 mm. The scintillator arrays consist of 14 × 14 lutetium oxyorthosilicate elements, with a crystal size of 0.43 × 0.43 mm at the front end and 0.80 × 0.43 mm at the back end, and the crystal elements are 13 mm long. The arrays are read out by 8 × 8 mm and 13 × 8 mm position-sensitive avalanche photodiodes (PSAPDs) placed at opposite ends of the array. Standard nuclear-instrumentation-module electronics and a custom-designed multiplexer are used for signal processing. The detector performance was measured, and all but the crystals at the very edge could be clearly resolved. The average intrinsic spatial resolution in the axial direction was 0.61 mm. A depth-of-interaction resolution of 1.7 mm was achieved. The sensitivity of the scanner at the center of the FOV was 1.02% for a lower energy threshold of 150 keV and 0.68% for a lower energy threshold of 250 keV. The spatial resolution within a FOV that can accommodate the entire mouse brain was approximately 0.6 mm using a 3-dimensional maximum-likelihood expectation maximization reconstruction. Images of a hot-rod microphantom showed that rods with a diameter of as low as 0.5 mm could be resolved. The first in vivo studies were performed using (18)F-fluoride and confirmed that a 0.6-mm resolution can be achieved in the mouse head in vivo. Brain imaging studies with (18)F-FDG were also performed. We developed a prototype PET scanner that can achieve a spatial resolution approaching the physical limits of a small-bore PET scanner set by positron range and detector interaction. We plan to add more detector rings to extend the axial FOV of the scanner and increase sensitivity. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

A high resolution prototype small-animal PET scanner dedicated to mouse brain imaging

PubMed Central

Yang, Yongfeng; Bec, Julien; Zhou, Jian; Zhang, Mengxi; Judenhofer, Martin S; Bai, Xiaowei; Di, Kun; Wu, Yibao; Rodriguez, Mercedes; Dokhale, Purushottam; Shah, Kanai S.; Farrell, Richard; Qi, Jinyi; Cherry, Simon R.

2017-01-01

A prototype small-animal PET scanner was developed based on depth-encoding detectors using dual-ended readout of very small scintillator elements to produce high and uniform spatial resolution suitable for imaging the mouse brain. Methods The scanner consists of 16 tapered dual-ended readout detectors arranged in a ring of diameter 61 mm. The axial field of view is 7 mm and the transaxial field of view is 30 mm. The scintillator arrays consist of 14×14 lutetium oxyorthosilicate (LSO) elements, with a crystal size of 0.43×0.43 mm2 at the front end and 0.80×0.43 mm2 at the back end, and the crystal elements are 13 mm long. The arrays are read out by 8×8 mm2 and a 13×8 mm2 position-sensitive avalanche photodiodes (PSAPDs) placed at opposite ends of the array. Standard nuclear instrumentation module (NIM) electronics and a custom designed multiplexer are used for signal processing. Results The detector performance was measured and all except the very edge crystals could be clearly resolved. The average detector intrinsic spatial resolution in the axial direction was 0.61 mm. A depth of interaction resolution of 1.7 mm was achieved. The sensitivity of the scanner at center of the field of view was 1.02% for a lower energy threshold of 150 keV and 0.68% for a lower energy threshold of 250 keV. The spatial resolution within a field of view that can accommodate the entire mouse brain was ~0.6 mm using a 3D Maximum Likelihood-Expectation Maximization (ML-EM) reconstruction algorithm. Images of a micro hot-rod phantom showed that rods with diameter down to 0.5 mm could be resolved. First in vivo studies were obtained using 18F-fluoride and confirmed that 0.6 mm resolution can be achieved in the mouse head in vivo. Brain imaging studies with 18F-fluorodeoxyglucose were also acquired. Conclusion A prototype PET scanner achieving a spatial resolution approaching the physical limits for a small-bore PET scanner set by positron range and acolinearity was developed. Future plans are to add more detector rings to extend the axial field of view of the scanner and increase sensitivity. PMID:27013696

Compton suppression and event triggering in a commercial data acquisition system

NASA Astrophysics Data System (ADS)

Tabor, Samuel; Caussyn, D. D.; Tripathi, Vandana; Vonmoss, J.; Liddick, S. N.

2012-10-01

A number of groups are starting to use flash digitizer systems to directly convert the preamplifier signals of high-resolution Ge detectors to a stream of digital data. Some digitizers are also equipped with software constant fraction discriminator algorithms capable of operating on the resulting digital data stream to provide timing information. Because of the dropping cost per channel of these systems, it should now be possible to also connect outputs of the Bismuth Germanate (BGO) scintillators used for Compton suppression to other digitizer inputs so that BGO logic signals can also be available in the same system. This provides the possibility to perform all the Compton suppression and multiplicity trigger logic within the digital system, thus eliminating the need for separate timing filter amplifiers (TFA), constant fraction discriminators (CFD), logic units, and lots of cables. This talk will describe the performance of such a system based on Pixie16 modules from XIA LLC with custom field programmable gate array (FPGA) programming for an array of Compton suppressed single Ge crystal and 4-crystal ``Clover'' detector array along with optional particle detectors. Initial tests of the system have produced results comparable with the current traditional system of individual electronics and peak sensing analog to digital converters. The advantages of the all digital system will be discussed.

35t Prototype Detector for Experiment at Long Base Line Neutrino Facility (ELBNF) Far Detector

NASA Astrophysics Data System (ADS)

Santucci, Gabriel; Elbnf Collaboration

2015-04-01

The 35ton prototype detector is a Liquid Argon Time Projection Chamber (LAr TPC) utilizing a membrane cryostat. It serves as a prototype for testing technology proposed for the ELBNF far detector. The construction of the prototype is an essential part of the ELBNF project due to the large amount of new technologies introduced for the far detector. In early 2014, it was shown that the membrane cryostat technology was able to reach and maintain the required LAr purity and an electron lifetime of 2.5 ms was achieved. The goals for the next phase include the installation of a fully functional TPC using the novel designs for the ELBNF far detector as much as possible. This includes the installation of the cold electronics, scintillation photon detectors and multiple Anode Plane Arrays with wrapped wires. In this talk I will review the status of the 35t prototype detector and describe what has been accomplished during 2014 and early 2015, including the commissioning phase and the early stages of data taking from cosmic-rays.

The Monte Carlo simulation of the Borexino detector

NASA Astrophysics Data System (ADS)

Agostini, M.; Altenmüller, K.; Appel, S.; Atroshchenko, V.; Bagdasarian, Z.; Basilico, D.; Bellini, G.; Benziger, J.; Bick, D.; Bonfini, G.; Borodikhina, L.; Bravo, D.; Caccianiga, B.; Calaprice, F.; Caminata, A.; Canepa, M.; Caprioli, S.; Carlini, M.; Cavalcante, P.; Chepurnov, A.; Choi, K.; D'Angelo, D.; Davini, S.; Derbin, A.; Ding, X. F.; Di Noto, L.; Drachnev, I.; Fomenko, K.; Formozov, A.; Franco, D.; Froborg, F.; Gabriele, F.; Galbiati, C.; Ghiano, C.; Giammarchi, M.; Goeger-Neff, M.; Goretti, A.; Gromov, M.; Hagner, C.; Houdy, T.; Hungerford, E.; Ianni, Aldo; Ianni, Andrea; Jany, A.; Jeschke, D.; Kobychev, V.; Korablev, D.; Korga, G.; Kryn, D.; Laubenstein, M.; Litvinovich, E.; Lombardi, F.; Lombardi, P.; Ludhova, L.; Lukyanchenko, G.; Machulin, I.; Magnozzi, M.; Manuzio, G.; Marcocci, S.; Martyn, J.; Meroni, E.; Meyer, M.; Miramonti, L.; Misiaszek, M.; Muratova, V.; Neumair, B.; Oberauer, L.; Opitz, B.; Ortica, F.; Pallavicini, M.; Papp, L.; Pocar, A.; Ranucci, G.; Razeto, A.; Re, A.; Romani, A.; Roncin, R.; Rossi, N.; Schönert, S.; Semenov, D.; Shakina, P.; Skorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Stokes, L. F. F.; Suvorov, Y.; Tartaglia, R.; Testera, G.; Thurn, J.; Toropova, M.; Unzhakov, E.; Vishneva, A.; Vogelaar, R. B.; von Feilitzsch, F.; Wang, H.; Weinz, S.; Wojcik, M.; Wurm, M.; Yokley, Z.; Zaimidoroga, O.; Zavatarelli, S.; Zuber, K.; Zuzel, G.

2018-01-01

We describe the Monte Carlo (MC) simulation of the Borexino detector and the agreement of its output with data. The Borexino MC "ab initio" simulates the energy loss of particles in all detector components and generates the resulting scintillation photons and their propagation within the liquid scintillator volume. The simulation accounts for absorption, reemission, and scattering of the optical photons and tracks them until they either are absorbed or reach the photocathode of one of the photomultiplier tubes. Photon detection is followed by a comprehensive simulation of the readout electronics response. The MC is tuned using data collected with radioactive calibration sources deployed inside and around the scintillator volume. The simulation reproduces the energy response of the detector, its uniformity within the fiducial scintillator volume relevant to neutrino physics, and the time distribution of detected photons to better than 1% between 100 keV and several MeV. The techniques developed to simulate the Borexino detector and their level of refinement are of possible interest to the neutrino community, especially for current and future large-volume liquid scintillator experiments such as Kamland-Zen, SNO+, and Juno.

Gamma ray spectroscopy employing divalent europium-doped alkaline earth halides and digital readout for accurate histogramming

DOEpatents

Cherepy, Nerine Jane; Payne, Stephen Anthony; Drury, Owen B.; Sturm, Benjamin W.

2016-02-09

According to one embodiment, a scintillator radiation detector system includes a scintillator, and a processing device for processing pulse traces corresponding to light pulses from the scintillator, where the processing device is configured to: process each pulse trace over at least two temporal windows and to use pulse digitization to improve energy resolution of the system. According to another embodiment, a scintillator radiation detector system includes a processing device configured to: fit digitized scintillation waveforms to an algorithm, perform a direct integration of fit parameters, process multiple integration windows for each digitized scintillation waveform to determine a correction factor, and apply the correction factor to each digitized scintillation waveform.

Subnanosecond Scintillation Detector

NASA Technical Reports Server (NTRS)

Hoenk, Michael (Inventor); Hennessy, John (Inventor); Hitlin, David (Inventor)

2017-01-01

A scintillation detector, including a scintillator that emits scintillation; a semiconductor photodetector having a surface area for receiving the scintillation, wherein the surface area has a passivation layer configured to provide a peak quantum efficiency greater than 40% for a first component of the scintillation, and the semiconductor photodetector has built in gain through avalanche multiplication; a coating on the surface area, wherein the coating acts as a bandpass filter that transmits light within a range of wavelengths corresponding to the first component of the scintillation and suppresses transmission of light with wavelengths outside said range of wavelengths; and wherein the surface area, the passivation layer, and the coating are controlled to increase the temporal resolution of the semiconductor photodetector.

Performance of SEM scintillation detector evaluated by modulation transfer function and detective quantum efficiency function.

PubMed

Bok, Jan; Schauer, Petr

2014-01-01

In the paper, the SEM detector is evaluated by the modulation transfer function (MTF) which expresses the detector's influence on the SEM image contrast. This is a novel approach, since the MTF was used previously to describe only the area imaging detectors, or whole imaging systems. The measurement technique and calculation of the MTF for the SEM detector are presented. In addition, the measurement and calculation of the detective quantum efficiency (DQE) as a function of the spatial frequency for the SEM detector are described. In this technique, the time modulated e-beam is used in order to create well-defined input signal for the detector. The MTF and DQE measurements are demonstrated on the Everhart-Thornley scintillation detector. This detector was alternated using the YAG:Ce, YAP:Ce, and CRY18 single-crystal scintillators. The presented MTF and DQE characteristics show good imaging properties of the detectors with the YAP:Ce or CRY18 scintillator, especially for a specific type of the e-beam scan. The results demonstrate the great benefit of the description of SEM detectors using the MTF and DQE. In addition, point-by-point and continual-sweep e-beam scans in SEM were discussed and their influence on the image quality was revealed using the MTF. © 2013 Wiley Periodicals, Inc.

Rayleigh scattering of linear alkylbenzene in large liquid scintillator detectors.

PubMed

Zhou, Xiang; Liu, Qian; Wurm, Michael; Zhang, Qingmin; Ding, Yayun; Zhang, Zhenyu; Zheng, Yangheng; Zhou, Li; Cao, Jun; Wang, Yifang

2015-07-01

Rayleigh scattering poses an intrinsic limit for the transparency of organic liquid scintillators. This work focuses on the Rayleigh scattering length of linear alkylbenzene (LAB), which will be used as the solvent of the liquid scintillator in the central detector of the Jiangmen Underground Neutrino Observatory. We investigate the anisotropy of the Rayleigh scattering in LAB, showing that the resulting Rayleigh scattering length will be significantly shorter than reported before. Given the same overall light attenuation, this will result in a more efficient transmission of photons through the scintillator, increasing the amount of light collected by the photosensors and thereby the energy resolution of the detector.

Detection of gamma-neutron radiation by solid-state scintillation detectors. Detection of gamma-neutron radiation by novel solid-state scintillation detectors

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

Ryzhikov, V.; Grinyov, B.; Piven, L.

It is known that solid-state scintillators can be used for detection of both gamma radiation and neutron flux. In the past, neutron detection efficiencies of such solid-state scintillators did not exceed 5-7%. At the same time it is known that the detection efficiency of the gamma-neutron radiation characteristic of nuclear fissionable materials is by an order of magnitude higher than the efficiency of detection of neutron fluxes alone. Thus, an important objective is the creation of detection systems that are both highly efficient in gamma-neutron detection and also capable of exhibiting high gamma suppression for use in the role ofmore » detection of neutron radiation. In this work, we present the results of our experimental and theoretical studies on the detection efficiency of fast neutrons from a {sup 239}Pu-Be source by the heavy oxide scintillators BGO, GSO, CWO and ZWO, as well as ZnSe(Te, O). The most probable mechanism of fast neutron interaction with nuclei of heavy oxide scintillators is the inelastic scattering (n, n'γ) reaction. In our work, fast neutron detection efficiencies were determined by the method of internal counting of gamma-quanta that emerge in the scintillator from (n, n''γ) reactions on scintillator nuclei with the resulting gamma energies of ∼20-300 keV. The measured efficiency of neutron detection for the scintillation crystals we considered was ∼40-50 %. The present work included a detailed analysis of detection efficiency as a function of detector and area of the working surface, as well as a search for new ways to create larger-sized detectors of lower cost. As a result of our studies, we have found an unusual dependence of fast neutron detection efficiency upon thickness of the oxide scintillators. An explanation for this anomaly may involve the competition of two factors that accompany inelastic scattering on the heavy atomic nuclei. The transformation of the energy spectrum of neutrons involved in the (n, n'γ) reactions towards lower energies and the isotropic character of scattering of the secondary neutrons may lead to the observed limitation of the length of effective interaction, since a fraction of the secondary neutrons that propagate in the forward direction are not subject to further inelastic scattering because of their substantially lower energy. At these reduced energies, it is the capture cross-section (n, γ) that becomes predominant, resulting in lower detection efficiency. Based on these results, several types of detectors have been envisioned for application in detection systems for nuclear materials. The testing results for one such detector are presented in this work. We have studied the possibility of creation of a composite detector with scintillator granules placed inside a transparent polymer material. Because of the low transparency of such a dispersed scintillator, better light collection conditions are ensured by incorporation of a light guide between the scintillator layers. This guide is made of highly transparent polymer material. The use of a high-transparency hydrogen-containing polymer material for light guides not only ensures optimum conditions of light collection in the detector, but also allows certain deceleration of neutron radiation, increasing its interaction efficiency with the composite scintillation panels; accordingly, the detector signal is increased by 5-8%. When fast neutrons interact with the scintillator material, the resulting inelastic scattering gamma-quanta emerge, having different energies and different delay times with respect to the moment of the neutron interaction with the nucleus of the scintillator material (delay times ranging from 1x10{sup -9} to 1.3x10{sup -6} s). These internally generated gamma-quanta interact with the scintillator, and the resulting scintillation light is recorded by the photo-receiver. Since neutron sources are also strong sources of low-energy gamma-radiation, the use of dispersed ZnSe(Te) scintillator material provides high gamma-radiation detection efficiency in that energy range. This new type of gamma-neutron detector is based on a 'sandwich' structure using a ZnSe composite film and light guide with a fast neutron detection efficiency of about 6%. Its high detection efficiency of low-energy gamma-radiation allows a substantial increase (by an order of magnitude) in the efficiency of detection of neutron sources and transuranic materials by means of simultaneous detection of accompanying gamma-radiation. The design and fabrication technology of this detector allows the creation of gamma-neutron detectors characterized by high sensitivity at relatively low costs (as compared with analogs using oxide scintillators) for portable inspection systems. The sandwich structure can be comprised of any number of plates, with no limitations on thickness or area.« less

Simulation the spatial resolution of an X-ray imager based on zinc oxide nanowires in anodic aluminium oxide membrane by using MCNP and OPTICS Codes

NASA Astrophysics Data System (ADS)

Samarin, S. N.; Saramad, S.

2018-05-01

The spatial resolution of a detector is a very important parameter for x-ray imaging. A bulk scintillation detector because of spreading of light inside the scintillator does't have a good spatial resolution. The nanowire scintillators because of their wave guiding behavior can prevent the spreading of light and can improve the spatial resolution of traditional scintillation detectors. The zinc oxide (ZnO) scintillator nanowire, with its simple construction by electrochemical deposition in regular hexagonal structure of Aluminum oxide membrane has many advantages. The three dimensional absorption of X-ray energy in ZnO scintillator is simulated by a Monte Carlo transport code (MCNP). The transport, attenuation and scattering of the generated photons are simulated by a general-purpose scintillator light response simulation code (OPTICS). The results are compared with a previous publication which used a simulation code of the passage of particles through matter (Geant4). The results verify that this scintillator nanowire structure has a spatial resolution less than one micrometer.

New fission-fragment detector for experiments at DANCE

NASA Astrophysics Data System (ADS)

Rusev, G.; Roman, A. R.; Daum, J. K.; Springs, R. K.; Bond, E. M.; Jandel, M.; Baramsai, B.; Bredeweg, T. A.; Couture, A.; Favalli, A.; Ianakiev, K. D.; Iliev, M. L.; Mosby, S.; Ullmann, J. L.; Walker, C. L.

2015-10-01

A fission-fragment detector based on thin scintillating films has been built to serve as a veto/trigger detector in neutron-induced fission measurements at DANCE. The fissile material is surrounded by scintillating films providing a 4 π detection of the fission fragments. The scintillation events caused by the fission fragment interactions in the films are registered with silicon photomultipliers. Design of the detector and test measurements are described. Work supported by the U.S. Department of Energy through the LANL/LDRD Program and the U.S. Department of Energy, Office of Science, Nuclear Physics under the Early Career Award No. LANL20135009.

A small-angle large-acceptance detection system for hadrons

NASA Astrophysics Data System (ADS)

Kalantar-Nayestanaki, N.; Bacelar, J. C. S.; Brandenburg, S.; Huisman, H.; Messchendorp, J. G.; Mul, F. A.; Schadmand, S.; van der Schaaf, K.; Schippers, J. M.; Volkerts, M.

2000-04-01

The performance of a segmented large-acceptance detector, capable of measuring particles at small forward angles, is presented. The Small-Angle Large-Acceptance Detector (SALAD), was built to handle very high rates of particles impinging on the detector. Particles down to a few MeV can be detected with it. The position of charged particles is measured by two Multi-Wire Proportional Chambers while scintillator blocks are used to measure the energy of the detected particle. A stack of thin scintillators placed behind the energy detectors allows for a hardware rejection (veto) of high-energy particles going through the scintillator blocks.

Study of light backgrounds from relativistic electrons in air light-guides

NASA Astrophysics Data System (ADS)

Riordan, S.; Zhao, Y. X.; Baunack, S.; Becker, D.; Clarke, C.; Dehmelt, K.; Deshpande, A.; Gericke, M.; Gläser, B.; Imai, K.; Kutz, T.; Maas, F. E.; McNulty, D.; Pan, J.; Park, S.; Rahman, S.; Souder, P. A.; Wang, P.; Wellman, B.; Kumar, K. S.

2018-07-01

The MOLLER experiment proposed at the Thomas Jefferson National Accelerator Facility plans a precision low energy determination of the weak mixing angle via the measurement of the parity-violating asymmetry in the scattering of high energy longitudinally polarized electrons from electrons bound in a liquid hydrogen target (Møller scattering). A relative measure of the scattering rate is planned to be obtained by intercepting the Møller scattered electrons with a circular array of thin fused silica tiles attached to air light guides, which facilitate the transport of Cherenkov photons generated within the tiles to photomultiplier tubes (PMTs). The scattered flux will also pass through the light guides of downstream tiles, generating additional Cherenkov as well as scintillation light and is a potential background. In order to estimate the rate of these backgrounds, a gas-filled tube detector was designed and deployed in an electron beam at the MAMI facility at Johannes Gutenberg University, Mainz, Germany. Described in this paper is the design of a detector to measure separately the scintillation and Cherenkov responses of gas mixtures from relativistic electrons, the results of studies of several gas mixtures with comparisons to simulations, and conclusions about the implications for the design of the MOLLER detector apparatus.

BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET

NASA Astrophysics Data System (ADS)

Brunner, S. E.; Schaart, D. R.

2017-06-01

Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times (CRT) between 325 ps and 400 ps FWHM have recently been developed. Before the introduction of L(Y)SO:Ce, BGO was used in many PET systems. In addition to a lower price, BGO offers a superior attenuation coefficient and a higher photoelectric fraction than L(Y)SO:Ce. However, BGO is generally considered an inferior TOF-PET scintillator. In recent years, TOF-PET detectors based on the Cherenkov effect have been proposed. However, the low Cherenkov photon yield in the order of  ˜10 photons per event complicates energy discrimination-a severe disadvantage in clinical PET. The optical characteristics of BGO, in particular its high transparency down to 310 nm and its high refractive index of  ˜2.15, are expected to make it a good Cherenkov radiator. Here, we study the feasibility of combining event timing based on Cherenkov emission with energy discrimination based on scintillation in BGO, as a potential approach towards a cost-effective TOF-PET detector. Rise time measurements were performed using a time-correlated single photon counting (TCSPC) setup implemented on a digital photon counter (DPC) array, revealing a prompt luminescent component likely to be due to Cherenkov emission. Coincidence timing measurements were performed using BGO crystals with a cross-section of 3 mm  ×  3 mm and five different lengths between 3 mm and 20 mm, coupled to DPC arrays. Non-Gaussian coincidence spectra with a FWHM of 200 ps were obtained with the 27 mm3 BGO cubes, while FWHM values as good as 330 ps were achieved with the 20 mm long crystals. The FWHM value was found to improve with decreasing temperature, while the FWTM value showed the opposite trend.

BGO as a hybrid scintillator / Cherenkov radiator for cost-effective time-of-flight PET.

PubMed

Brunner, S E; Schaart, D R

2017-06-07

Due to detector developments in the last decade, the time-of-flight (TOF) method is now commonly used to improve the quality of positron emission tomography (PET) images. Clinical TOF-PET systems based on L(Y)SO:Ce crystals and silicon photomultipliers (SiPMs) with coincidence resolving times (CRT) between 325 ps and 400 ps FWHM have recently been developed. Before the introduction of L(Y)SO:Ce, BGO was used in many PET systems. In addition to a lower price, BGO offers a superior attenuation coefficient and a higher photoelectric fraction than L(Y)SO:Ce. However, BGO is generally considered an inferior TOF-PET scintillator. In recent years, TOF-PET detectors based on the Cherenkov effect have been proposed. However, the low Cherenkov photon yield in the order of  ∼10 photons per event complicates energy discrimination-a severe disadvantage in clinical PET. The optical characteristics of BGO, in particular its high transparency down to 310 nm and its high refractive index of  ∼2.15, are expected to make it a good Cherenkov radiator. Here, we study the feasibility of combining event timing based on Cherenkov emission with energy discrimination based on scintillation in BGO, as a potential approach towards a cost-effective TOF-PET detector. Rise time measurements were performed using a time-correlated single photon counting (TCSPC) setup implemented on a digital photon counter (DPC) array, revealing a prompt luminescent component likely to be due to Cherenkov emission. Coincidence timing measurements were performed using BGO crystals with a cross-section of 3 mm  ×  3 mm and five different lengths between 3 mm and 20 mm, coupled to DPC arrays. Non-Gaussian coincidence spectra with a FWHM of 200 ps were obtained with the 27 mm 3 BGO cubes, while FWHM values as good as 330 ps were achieved with the 20 mm long crystals. The FWHM value was found to improve with decreasing temperature, while the FWTM value showed the opposite trend.

Simultaneous beta and gamma spectroscopy

DOEpatents

Farsoni, Abdollah T.; Hamby, David M.

2010-03-23

A phoswich radiation detector for simultaneous spectroscopy of beta rays and gamma rays includes three scintillators with different decay time characteristics. Two of the three scintillators are used for beta detection and the third scintillator is used for gamma detection. A pulse induced by an interaction of radiation with the detector is digitally analyzed to classify the type of event as beta, gamma, or unknown. A pulse is classified as a beta event if the pulse originated from just the first scintillator alone or from just the first and the second scintillator. A pulse from just the third scintillator is recorded as gamma event. Other pulses are rejected as unknown events.

64-element photodiode array for scintillation detection of x-rays

NASA Astrophysics Data System (ADS)

Wegrzecki, Maciej; Wolski, Dariusz; Bar, Jan; Budzyński, Tadeusz; Chłopik, Arkadiusz; Grabiec, Piotr; Kłos, Helena; Panas, Andrzej; Piotrowski, Tadeusz; Słysz, Wojciech; Stolarski, Maciej; Szmigiel, Dariusz; Wegrzecka, Iwona; Zaborowski, Michał

2014-08-01

The paper presents the design, technology and parameters of a new, silicon 64-element linear photodiode array developed at the Institute of Electron Technology (ITE) for the detection of scintillations emitted by CsI scintillators (λ≈550 nm). The arrays are used in a device for examining the content of containers at border crossings under development at the National Centre for Nuclear Research. Two arrays connected with a scintillator block (128 CsI scintillators) form a 128-channel detection module. The array consists of 64 epiplanar photodiode structures (5.1 × 7.2 mm) and a 5.3 mm module. p+-ν-n+ photodiode structures are optimised for the detection of radiation of λ≈ 550 nm wavelength with no voltage applied (photovoltaic mode). The structures are mounted on an epoxy-glass laminate substrate, copper-clad on both sides, on which connections with a common anode and separate cathode leads are located. The photosensitive surface of photodiodes is covered with a special silicone gel, which protects photodiodes against the mechanical impact of scintillators

X-ray imaging performance of scintillator-filled silicon pore arrays

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

Simon, Matthias; Engel, Klaus Juergen; Menser, Bernd

2008-03-15

The need for fine detail visibility in various applications such as dental imaging, mammography, but also neurology and cardiology, is the driver for intensive efforts in the development of new x-ray detectors. The spatial resolution of current scintillator layers is limited by optical diffusion. This limitation can be overcome by a pixelation, which prevents optical photons from crossing the interface between two neighboring pixels. In this work, an array of pores was etched in a silicon wafer with a pixel pitch of 50 {mu}m. A very high aspect ratio was achieved with wall thicknesses of 4-7 {mu}m and pore depthsmore » of about 400 {mu}m. Subsequently, the pores were filled with Tl-doped cesium iodide (CsI:Tl) as a scintillator in a special process, which includes powder melting and solidification of the CsI. From the sample geometry and x-ray absorption measurement the pore fill grade was determined to be 75%. The scintillator-filled samples have a circular active area of 16 mm diameter. They are coupled with an optical sensor binned to the same pixel pitch in order to measure the x-ray imaging performance. The x-ray sensitivity, i.e., the light output per absorbed x-ray dose, is found to be only 2.5%-4.5% of a commercial CsI-layer of similar thickness, thus very low. The efficiency of the pores to transport the generated light to the photodiode is estimated to be in the best case 6.5%. The modulation transfer function is 40% at 4 lp/mm and 10%-20% at 8 lp/mm. It is limited most likely by the optical gap between scintillator and sensor and by K-escape quanta. The detective quantum efficiency (DQE) is determined at different beam qualities and dose settings. The maximum DQE(0) is 0.28, while the x-ray absorption with the given thickness and fill factor is 0.57. High Swank noise is suspected to be the reason, mainly caused by optical scatter inside the CsI-filled pores. The results are compared to Monte Carlo simulations of the photon transport inside the pore array structure. In addition, some x-ray images of technical and anatomical phantoms are shown. This work shows that scintillator-filled pore arrays can provide x-ray imaging with high spatial resolution, but are not suitable in their current state for most of the applications in medical imaging, where increasing the x-ray doses cannot be tolerated.« less

A New Columnar CsI(Tl) Scintillator for iQID detectors

PubMed Central

Han, Ling; Miller, Brian W.; Barber, H. Bradford; Nagarkar, Vivek V.; Furenlid, Lars R.

2015-01-01

A 1650 μm thick columnar CsI(Tl) scintillator for upgrading iQID detectors, which is a high-resolution photon-counting gamma-ray and x-ray detector recently developed at the Center for Gamma-Ray Imaging (CGRI), has been studied in terms of sensitivity, spatial resolution and depth-of-interaction effects. To facilitate these studies, a new frame-parsing algorithm for processing raw event data is also proposed that has more degrees of freedom in data processing and can discriminate against a special kind of noise present in some low-cost intensifiers. The results show that in comparison with a 450 μm-thickness columnar CsI(Tl) scintillator, the 1650 μm thick CsI(Tl) scintillator provides more than twice the sensitivity at the expense of some spatial resolution degradation. The depth-of-interaction study also shows that event size and amplitude vary with scintillator thickness, which can assist in future detector simulations and 3D-interaction-position estimation. PMID:26146444

A New Columnar CsI(Tl) Scintillator for iQID detectors.

PubMed

Han, Ling; Miller, Brian W; Barber, H Bradford; Nagarkar, Vivek V; Furenlid, Lars R

2014-09-12

A 1650 μm thick columnar CsI(Tl) scintillator for upgrading iQID detectors, which is a high-resolution photon-counting gamma-ray and x-ray detector recently developed at the Center for Gamma-Ray Imaging (CGRI), has been studied in terms of sensitivity, spatial resolution and depth-of-interaction effects. To facilitate these studies, a new frame-parsing algorithm for processing raw event data is also proposed that has more degrees of freedom in data processing and can discriminate against a special kind of noise present in some low-cost intensifiers. The results show that in comparison with a 450 μm-thickness columnar CsI(Tl) scintillator, the 1650 μm thick CsI(Tl) scintillator provides more than twice the sensitivity at the expense of some spatial resolution degradation. The depth-of-interaction study also shows that event size and amplitude vary with scintillator thickness, which can assist in future detector simulations and 3D-interaction-position estimation.

Organic Scintillator Detector Response Simulations with DRiFT

DOE PAGES

Andrews, Madison Theresa; Bates, Cameron Russell; Mckigney, Edward Allen; ...

2016-06-11

Here, this work presents the organic scintillation simulation capabilities of DRiFT, a post-processing Detector Response Function Toolkit for MCNPR output. DRiFT is used to create realistic scintillation detector response functions to incident neutron and gamma mixed- field radiation. As a post-processing tool, DRiFT leverages the extensively validated radiation transport capabilities of MCNPR ®6, which also provides the ability to simulate complex sources and geometries. DRiFT is designed to be flexible, it allows the user to specify scintillator material, PMT type, applied PMT voltage, and quenching data used in simulations. The toolkit's capabilities, which include the generation of pulse shape discriminationmore » plots and full-energy detector spectra, are demonstrated in a comparison of measured and simulated neutron contributions from 252Cf and PuBe, and photon spectra from 22Na and 228Th sources. DRiFT reproduced energy resolution effects observed in EJ-301 measurements through the inclusion of scintillation yield variances, photon transport noise, and PMT photocathode and multiplication noise.« less

Organic scintillator detector response simulations with DRiFT

NASA Astrophysics Data System (ADS)

Andrews, M. T.; Bates, C. R.; McKigney, E. A.; Solomon, C. J.; Sood, A.

2016-09-01

This work presents the organic scintillation simulation capabilities of DRiFT, a post-processing Detector Response Function Toolkit for MCNP® output. DRiFT is used to create realistic scintillation detector response functions to incident neutron and gamma mixed-field radiation. As a post-processing tool, DRiFT leverages the extensively validated radiation transport capabilities of MCNP® 6 , which also provides the ability to simulate complex sources and geometries. DRiFT is designed to be flexible, it allows the user to specify scintillator material, PMT type, applied PMT voltage, and quenching data used in simulations. The toolkit's capabilities, which include the generation of pulse shape discrimination plots and full-energy detector spectra, are demonstrated in a comparison of measured and simulated neutron contributions from 252Cf and PuBe, and photon spectra from 22Na and 228Th sources. DRiFT reproduced energy resolution effects observed in EJ-301 measurements through the inclusion of scintillation yield variances, photon transport noise, and PMT photocathode and multiplication noise.

X-ray detection properties of plastic scintillators containing surface-modified Bi2O3 nanoparticles

NASA Astrophysics Data System (ADS)

Hiyama, Fumiyuki; Noguchi, Takio; Koshimizu, Masanori; Kishimoto, Shunji; Haruki, Rie; Nishikido, Fumihiko; Fujimoto, Yutaka; Aida, Tsutomu; Takami, Seiichi; Adschiri, Tadafumi; Asai, Keisuke

2018-05-01

Plastic scintillators containing Bi2O3 nanoparticles (NPs) were developed as detectors for X-ray synchrotron radiation. A hydrothermal method was used to synthesize the NPs that had average particle sizes of less than 10 nm. Higher NP concentration led to a higher detection efficiency at 67.4 keV. The light yield of the scintillator containing 5 wt % Bi2O3 NPs was comparable with or higher than that of the commercially available plastic scintillator, EJ 256. The time resolution of the developed scintillation detector equipped with each sample scintillator was approximately 0.6 ns. Dispersion of nanoparticles within plastic scintillators is generally applicable and has wide application as a method for preparation of plastic scintillators for detecting X-ray synchrotron radiation.

Applications of a Fast Neutron Detector System to Verification of Special Nuclear Materials

NASA Astrophysics Data System (ADS)

Mayo, Douglas R.; Byrd, Roger C.; Ensslin, Norbert; Krick, Merlyn S.; Mercer, David J.; Miller, Michael C.; Prettyman, Thomas H.; Russo, Phyllis A.

1998-04-01

An array of boron-loaded plastic optically coupled to bismuth germanate scintillators has been developed to detect neutrons for measurement of special nuclear materials. The phoswiched detection system has the advantage of a high neutron detection efficiency and short die-away time. This is achieved by mixing the moderator (plastic) and the detector (^10B) at the molecular level. Simulations indicate that the neutron capture probabilities equal or exceed those of the current thermal neutron multiplicity techniques which have the moderator (polyethylene) and detectors (^3He gas proportional tubes) macroscopically separate. Experiments have been performed to characterize the response of these detectors and validate computer simulations. The fast neutron detection system may be applied to the quantitative assay of plutonium in high (α,n) backgrounds, with emphasis on safeguards and enviromental scenarios. Additional applications of the insturment, in a non-quantative mode, has been tested for possible verification activities involving dismantlement of nuclear weapons. A description of the detector system, simulations and preliminary data will be presented.

Development of a front-end analog circuit for multi-channel SiPM readout and performance verification for various PET detector designs

NASA Astrophysics Data System (ADS)

Ko, Guen Bae; Yoon, Hyun Suk; Kwon, Sun Il; Lee, Chan Mi; Ito, Mikiko; Hong, Seong Jong; Lee, Dong Soo; Lee, Jae Sung

2013-03-01

Silicon photomultipliers (SiPMs) are outstanding photosensors for the development of compact imaging devices and hybrid imaging systems such as positron emission tomography (PET)/ magnetic resonance (MR) scanners because of their small size and MR compatibility. The wide use of this sensor for various types of scintillation detector modules is being accelerated by recent developments in tileable multichannel SiPM arrays. In this work, we present the development of a front-end readout module for multi-channel SiPMs. This readout module is easily extendable to yield a wider detection area by the use of a resistive charge division network (RCN). We applied this readout module to various PET detectors designed for use in small animal PET/MR, optical fiber PET/MR, and double layer depth of interaction (DOI) PET. The basic characteristics of these detector modules were also investigated. The results demonstrate that the PET block detectors developed using the readout module and tileable multi-channel SiPMs had reasonable performance.

SCINTILLATION EXPOSURE RATE DETECTOR

DOEpatents

Spears, W.G.

1960-11-01

A radiation detector for gamma and x rays is described. The detector comprises a scintillation crystal disposed between a tantalum shield and the input of a photomultiplier tube, the crystal and the shield cooperating so that their combined response to a given quantity of radiation at various energy levels is substantially constant.

Detection of Extensive Cosmic Air Showers by Small Scintillation Detectors with Wavelength-Shifting Fibres

ERIC Educational Resources Information Center

Aiola, Salvatore; La Rocca, Paola; Riggi, Francesco; Riggi, Simone

2012-01-01

A set of three small scintillation detectors was employed to measure correlated events due to the passage of cosmic muons originating from extensive air showers. The coincidence rate between (any) two detectors was extracted as a function of their relative distance. The difference between the arrival times in three non-aligned detectors was used…

Energy dependent response of plastic scintillation detectors to photon radiation of low to medium energy.

PubMed

Ebenau, Melanie; Radeck, Désirée; Bambynek, Markus; Sommer, Holger; Flühs, Dirk; Spaan, Bernhard; Eichmann, Marion

2016-08-01

Plastic scintillation detectors are promising candidates for the dosimetry of low- to medium-energy photons but quantitative knowledge of their energy response is a prerequisite for their correct use. The purpose of this study was to characterize the energy dependent response of small scintillation detectors (active volume <1 mm(3)) made from the commonly used plastic scintillator BC400. Different detectors made from BC400 were calibrated at a number of radiation qualities ranging from 10 to 280 kV and at a (60)Co beam. All calibrations were performed at the Physikalisch-Technische Bundesanstalt, the National Metrology Institute of Germany. The energy response in terms of air kerma, dose to water, and dose to the scintillator was determined. Conversion factors from air kerma to dose to water and to dose to the scintillator were derived from Monte Carlo simulations. In order to quantitatively describe the energy dependence, a semiempirical model known as unimolecular quenching or Birks' formula was fitted to the data and from this the response to secondary electrons generated within the scintillator material BC400 was derived. The detector energy response in terms of air kerma differs for different scintillator sizes and different detector casings. It is therefore necessary to take attenuation within the scintillator and in the casing into account when deriving the response in terms of dose to water from a calibration in terms of air kerma. The measured energy response in terms of dose to water for BC400 cannot be reproduced by the ratio of mean mass energy-absorption coefficients for polyvinyl toluene to water but shows evidence of quenching. The quenching parameter kB in Birks' formula was determined to be kB = (12.3 ± 0.9) mg MeV(-1) cm(-2). The energy response was quantified relative to the response to (60)Co which is the common radiation quality for the calibration of therapy dosemeters. The observed energy dependence could be well explained with the assumption of ionization quenching as described by Birks' formula. Plastic scintillation detectors should be calibrated at the same radiation quality that they will be used at and changes of the spectrum within the application need to be considered. The authors results can be used to evaluate the range of validity of a given calibration.

Highly multiplexed signal readout for a time-of-flight positron emission tomography detector based on silicon photomultipliers

PubMed Central

Cates, Joshua W.; Bieniosek, Matthew F.; Levin, Craig S.

2017-01-01

Abstract. Maintaining excellent timing resolution in the generation of silicon photomultiplier (SiPM)-based time-of-flight positron emission tomography (TOF-PET) systems requires a large number of high-speed, high-bandwidth electronic channels and components. To minimize the cost and complexity of a system’s back-end architecture and data acquisition, many analog signals are often multiplexed to fewer channels using techniques that encode timing, energy, and position information. With progress in the development SiPMs having lower dark noise, after pulsing, and cross talk along with higher photodetection efficiency, a coincidence timing resolution (CTR) well below 200 ps FWHM is now easily achievable in single pixel, bench-top setups using 20-mm length, lutetium-based inorganic scintillators. However, multiplexing the output of many SiPMs to a single channel will significantly degrade CTR without appropriate signal processing. We test the performance of a PET detector readout concept that multiplexes 16 SiPMs to two channels. One channel provides timing information with fast comparators, and the second channel encodes both position and energy information in a time-over-threshold-based pulse sequence. This multiplexing readout concept was constructed with discrete components to process signals from a 4×4 array of SensL MicroFC-30035 SiPMs coupled to 2.9×2.9×20  mm3 Lu1.8Gd0.2SiO5 (LGSO):Ce (0.025 mol. %) scintillators. This readout method yielded a calibrated, global energy resolution of 15.3% FWHM at 511 keV with a CTR of 198±2  ps FWHM between the 16-pixel multiplexed detector array and a 2.9×2.9×20  mm3 LGSO-SiPM reference detector. In summary, results indicate this multiplexing scheme is a scalable readout technique that provides excellent coincidence timing performance. PMID:28382312

Development of a Cost-Effective Modular Pixelated NaI(Tl) Detector for Clinical SPECT Applications

PubMed Central

Rozler, Mike; Liang, Haoning; Chang, Wei

2013-01-01

A new pixelated detector for high-resolution clinical SPECT applications was designed and tested. The modular detector is based on a scintillator block comprised of 2.75×2.75×10 mm3 NaI(Tl) pixels and decoded by an array of 51 mm diameter single-anode PMTs. Several configurations, utilizing two types of PMTs, were evaluated using a collimated beam source to measure positioning accuracy directly. Good pixel separation was observed, with correct pixel identification ranging from 60 to 72% averaged over the entire area of the modules, depending on the PMT type and configuration. This translates to a significant improvement in positioning accuracy compared to continuous slab detectors of the same thickness, along with effective reduction of “dead” space at the edges. The observed 10% average energy resolution compares well to continuous slab detectors. The combined performance demonstrates the suitability of pixelated detectors decoded with a relatively small number of medium-sized PMTs as a cost-effective approach for high resolution clinical SPECT applications, in particular those involving curved detector geometries. PMID:24146436

Basic performance of Mg co-doped new scintillator used for TOF-DOI-PET systems

NASA Astrophysics Data System (ADS)

Kobayashi, Takahiro; Yamamoto, Seiichi; Okumura, Satoshi; Yeom, Jung Yeol; Kamada, Kei; Yoshikawa, Akira

2017-01-01

Phoswich depth-of-interaction (DOI) detectors utilizing multiple scintillators with different decay time are a useful device for developing a high spatial resolution, high sensitivity PET scanner. However, in order to apply pulse shape discrimination (PSD), there are not many combinations of scintillators for which phoswich technique can be implemented. Ce doped Gd3Ga3Al2O12 (GFAG) is a recently developed scintillator with a fast decay time. This scintillator is similar to Ce doped Gd3Al2Ga3O12 (GAGG), which is a promising scintillator for PET detector with high light yield. By stacking these scintillators, it may be possible to realize a high spatial resolution and high timing resolution phoswich DOI detector. Such phoswich DOI detector may be applied to time-of-flight (TOF) systems with high timing performance. Therefore, in this study, we tested the basic performance of the new scintillator -GFAG for use in a TOF phoswich detector. The measured decay time of a GFAG element of 2.9 mmx2.9 mmx10 mm in dimension, which was optically coupled to a photomultiplier tube (PMT), was faster (66 ns) than that of same sized GAGG (103 ns). The energy resolution of the GFAG element was 5.7% FWHM which was slightly worse than that of GAGG with 4.9% FWHM for 662 keV gamma photons without saturation correction. Then we assembled the GFAG and the GAGG crystals in the depth direction to form a 20 mm long phoswich element (GFAG/GAGG). By pulse shape analysis, the two types of scintillators were clearly resolved. Measured timing resolution of a pair of opposing GFAG/GAGG phoswich scintillator coupled to Silicon Photomultipliers (Si-PM) was good with coincidence resolving time of 466 ps FWHM. These results indicate that the GFAG combined with GAGG can be a candidate for TOF-DOI-PET systems.

Proton-induced radioactivity in NaI (Tl) scintillation detectors

NASA Technical Reports Server (NTRS)

Fishman, G. J.

1977-01-01

Radioactivity induced by protons in sodium iodide scintillation crystals were calculated and directly measured. These data are useful in determining trapped radiation and cosmic-ray induced, background-counting rates in spaceborne detectors.

Thin-film-based scintillators for hard x-ray microimaging detectors: the ScinTAX Project

NASA Astrophysics Data System (ADS)

Rack, A.; Cecilia, A.; Douissard, P.-A.; Dupré, K.; Wesemann, V.; Baumbach, T.; Couchaud, M.; Rochet, X.; Riesemeier, H.; Radtke, M.; Martin, T.

2014-09-01

The project ScinTAX developed novel thin scintillating films for the application in high performance X-ray imaging and subsequent introduced new X-ray detectors to the market. To achieve this aim lutetium orthosilicate (LSO) scintillators doped with different activators were grown successfully by liquid phase epitaxy. The high density of LSO (7.4 g/cm3), the effective atomic number (65.2) and the high light yield make this scintillator highly applicable for indirect X-ray detection in which the ionizing radiation is converted into visible light and then registered by a digital detector. A modular indirect detection system has been developed to fully exploit the potential of this thin film scintillator for radiographic and tomographic imaging. The system is compatible for high-resolution imaging with moderate dose as well as adaptable to intense high-dose applications where radiation hard microimaging detectors are required. This proceedings article shall review the achieved performances and technical details on this high-resolution detector system which is now available. A selected example application demonstrates the great potential of the optimized detector system for hard X-ray microimaging, i.e. either to improve image contrast due to the availability of efficient thin crystal films or to reduce the dose to the sample.

Rayleigh scattering of linear alkylbenzene in large liquid scintillator detectors

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

Zhou, Xiang, E-mail: xiangzhou@whu.edu.cn; Zhang, Zhenyu; Liu, Qian

2015-07-15

Rayleigh scattering poses an intrinsic limit for the transparency of organic liquid scintillators. This work focuses on the Rayleigh scattering length of linear alkylbenzene (LAB), which will be used as the solvent of the liquid scintillator in the central detector of the Jiangmen Underground Neutrino Observatory. We investigate the anisotropy of the Rayleigh scattering in LAB, showing that the resulting Rayleigh scattering length will be significantly shorter than reported before. Given the same overall light attenuation, this will result in a more efficient transmission of photons through the scintillator, increasing the amount of light collected by the photosensors and therebymore » the energy resolution of the detector.« less

Experimental study of a depth-encoding PET detector inserting horizontal-striped glass between crystal layers

NASA Astrophysics Data System (ADS)

Yang, J.; Kim, K. B.; Choi, Y.; Kang, J.

2018-04-01

A depth-encoding positron emission tomography (PET) detector inserting a horizontal-striped glass between pixilated scintillation crystal layers was developed and experimentally evaluated. The detector consists of 2-layers of 4×4 LYSO array arranged with a 3.37 mm pitch. Horizontal-striped glasses with 1×4 array with different thickness of 3, 4 and 5 mm were inserted between top- and bottom-crystal layers. Bottom surface of bottom-layer was optically coupled to a 4×4 GAPD array. Sixteen output signals from DOI-PET detector were multiplexed by modified resistive charge division (RCD) networks and multiplexed signals were fed into custom-made charge-sensitive preamplifiers. The four amplified signals were digitized and recorded by the custom-made DAQ system based on FPGA. The four digitized outputs were post-processed and converted to flood histograms for each interaction event. Experimental results revealed that all crystal pixels were clearly identified on the 2D flood histogram without overlapping. Patterns of the 2D flood histogram were constituted with arrangements of [bottom–top–bottom–top–\\ldots–top–bottom–top–bottom] crystal responses in X-direction. These could be achieved by employing horizontal-striped glass that controlled the extent of light dispersion towards the X-direction in crystal layers for generation of a different position mapping for each layer and the modified RCD network that controls degree of charge sharing in readout electronics for reduction of identification error. This study demonstrated the proposed DOI-PET detector can extract the 3D γ-ray interaction position without considerable performance degradation of PET detector from the 2D flood histogram.

Evaluation of Matrix9 silicon photomultiplier array for small-animal PET.

PubMed

Du, Junwei; Schmall, Jeffrey P; Yang, Yongfeng; Di, Kun; Roncali, Emilie; Mitchell, Gregory S; Buckley, Steve; Jackson, Carl; Cherry, Simon R

2015-02-01

The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL's front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm(2) and the total size of the detector head is 47.8 × 46.3 mm(2). Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomography (PET). Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0-32.5 V in 0.5 V intervals) and at different temperatures (5 °C-25 °C in 5 °C degree steps) to find the optimal operating conditions. The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. In summary, the Matrix9 detector system can resolve high-resolution scintillator arrays common in small-animal PET with adequate energy resolution and timing resolution over a large detector area. The modular design of the Matrix9 detector allows it to be used as a building block for simple, low channel-count, yet high performance, small animal PET or PET/MRI systems.

Evaluation of Matrix9 silicon photomultiplier array for small-animal PET

PubMed Central

Du, Junwei; Schmall, Jeffrey P.; Yang, Yongfeng; Di, Kun; Roncali, Emilie; Mitchell, Gregory S.; Buckley, Steve; Jackson, Carl; Cherry, Simon R.

2015-01-01

Purpose: The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL’s front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm2 and the total size of the detector head is 47.8 × 46.3 mm2. Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomography (PET). Methods: Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0–32.5 V in 0.5 V intervals) and at different temperatures (5 °C–25 °C in 5 °C degree steps) to find the optimal operating conditions. Results: The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. Conclusions: In summary, the Matrix9 detector system can resolve high-resolution scintillator arrays common in small-animal PET with adequate energy resolution and timing resolution over a large detector area. The modular design of the Matrix9 detector allows it to be used as a building block for simple, low channel-count, yet high performance, small animal PET or PET/MRI systems. PMID:25652479

Evaluation of Matrix9 silicon photomultiplier array for small-animal PET

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

Du, Junwei, E-mail: jwdu@ucdavis.edu; Schmall, Jeffrey P.; Yang, Yongfeng

Purpose: The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL’s front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm{sup 2} and the total size of the detector head is 47.8 × 46.3 mm{sup 2}. Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomographymore » (PET). Methods: Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0–32.5 V in 0.5 V intervals) and at different temperatures (5 °C–25 °C in 5 °C degree steps) to find the optimal operating conditions. Results: The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays. Conclusions: In summary, the Matrix9 detector system can resolve high-resolution scintillator arrays common in small-animal PET with adequate energy resolution and timing resolution over a large detector area. The modular design of the Matrix9 detector allows it to be used as a building block for simple, low channel-count, yet high performance, small animal PET or PET/MRI systems.« less

The XENON100 Dark Matter Experiment: Design, Construction, Calibration and 2010 Search Results with Improved Measurement of the Scintillation Response of Liquid Xenon to Low-Energy Nuclear Recoils

NASA Astrophysics Data System (ADS)

Plante, Guillaume

An impressive array of astrophysical observations suggest that 83% of the matter in the universe is in a form of non-luminous, cold, collisionless, non-baryonic dark matter. Several extensions of the Standard Model of particle physics aimed at solving the hierarchy problem predict stable weakly interacting massive particles (WIMPs) that could naturally have the right cosmological relic abundance today to compose most of the dark matter if their interactions with normal matter are on the order of a weak scale cross section. These candidates also have the added benefit that their properties and interaction rates can be computed in a well defined particle physics model. A considerable experimental effort is currently under way to uncover the nature of dark matter. One method of detecting WIMP dark matter is to look for its interactions in terrestrial detectors where it is expected to scatter off nuclei. In 2007, the XENON10 experiment took the lead over the most sensitive direct detection dark matter search in operation, the CDMS II experiment, by probing spin-independent WIMP-nucleon interaction cross sections down to sigmachi N ˜ 5 x 10-44 cm 2 at 30 GeV/c2. Liquefied noble gas detectors are now among the technologies at the forefront of direct detection experiments. Liquid xenon (LXe), in particular, is a well suited target for WIMP direct detection. It is easily scalable to larger target masses, allows discrimination between nuclear recoils and electronic recoils, and has an excellent stopping power to shield against external backgrounds. A particle losing energy in LXe creates both ionization electrons and scintillation light. In a dual-phase LXe time projection chamber (TPC) the ionization electrons are drifted and extracted into the gas phase where they are accelerated to amplify the charge signal into a proportional scintillation signal. These two signals allow the three-dimensional localization of events with millimeter precision and the ability to fiducialize the target volume, yielding an inner core with a very low background. Additionally, the ratio of ionization and scintillation can be used to discriminate between nuclear recoils, from neutrons or WIMPs, and electronic recoils, from gamma or beta backgrounds. In these detectors, the energy scale is based on the scintillation signal of nuclear recoils and consequently the precise knowledge of the scintillation efficiency of nuclear recoils in LXe is of prime importance. Inspired by the success of the XENON10 experiment, the XENON collaboration designed and built a new, ten times larger, with a one hundred times lower background, LXe TPC to search for dark matter. It is currently the most sensitive direct detection experiment in operation. In order to shed light on the response of LXe to low energy nuclear recoils a new single phase detector designed specifically for the measurement of the scintillation efficiency of nuclear recoils was also built. In 2011, the XENON100 dark matter results from 100 live days set the most stringent limit on the spin-independent WIMP-nucleon interaction cross section over a wide range of masses, down to sigma chi N ˜ 7 x 10-45 cm2 at 50 GeV/c2, almost an order of magnitude improvement over XENON10 in less than four years. This thesis describes the research conducted in the context of the XENON100 dark matter search experiment. I describe the initial simulation results and ideas that influenced the design of the XENON100 detector, the construction and assembly steps that lead into its concrete realization, the detector and its subsystems, a subset of the calibration results of the detector, and finally dark matter exclusion limits. I also describe in detail the new improved measurement of the important quantity for the interpretation of results from LXe dark matter searches, the scintillation efficiency of low-energy nuclear recoils in LXe.

Large volume flow-through scintillating detector

DOEpatents

Gritzo, Russ E.; Fowler, Malcolm M.

1995-01-01

A large volume flow through radiation detector for use in large air flow situations such as incinerator stacks or building air systems comprises a plurality of flat plates made of a scintillating material arranged parallel to the air flow. Each scintillating plate has a light guide attached which transfers light generated inside the scintillating plate to an associated photomultiplier tube. The output of the photomultiplier tubes are connected to electronics which can record any radiation and provide an alarm if appropriate for the application.

Skin contamination dosimeter

DOEpatents

Hamby, David M [Corvallis, OR; Farsoni, Abdollah T [Corvallis, OR; Cazalas, Edward [Corvallis, OR

2011-06-21

A technique and device provides absolute skin dosimetry in real time at multiple tissue depths simultaneously. The device uses a phoswich detector which has multiple scintillators embedded at different depths within a non-scintillating material. A digital pulse processor connected to the phoswich detector measures a differential distribution (dN/dH) of count rate N as function of pulse height H for signals from each of the multiple scintillators. A digital processor computes in real time from the differential count-rate distribution for each of multiple scintillators an estimate of an ionizing radiation dose delivered to each of multiple depths of skin tissue corresponding to the multiple scintillators embedded at multiple corresponding depths within the non-scintillating material.

Simulation study of PET detector configuration with thick light guide and GAPD array having large-area microcells for high effective quantum efficiency.

PubMed

Kang, Jihoon; Choi, Yong

2016-07-01

Light sharing PET detector configuration coupled with thick light guide and Geiger-mode avalanche photodiode (GAPD) with large-area microcells was proposed to overcome the energy non-linearity problem and to obtain high light collection efficiency (LCE). A Monte-Carlo simulation was conducted for the three types of LSO block, 4 × 4 array of 3 × 3 × 20 mm(3) discrete crystals, 6 × 6 array of 2 × 2 × 20 mm(3) discrete crystals, and 12 × 12 array of 1 × 1 × 20 mm(3) discrete crystals, to investigate the scintillation light distribution after conversion of the γ-rays in LSO. The incident photons were read out by three types of 4 × 4 array photosensors, which were PSPMT of 25% quantum efficiency (QE), GAPD1 with 50 × 50 µm(2) microcells of 30% photon detection efficiency (PDE) and GAPD2 with 100 × 100 µm(2) of 45% PDE. The number of counted photons in each photosensor was analytically calculated. The LCE, linearity and flood histogram were examined for each PET detector module having 99 different configurations as a function of light guide thickness ranging from 0 to 10 mm. The performance of PET detector modules based on GAPDs was considerably improved by using the thick light guide. The LCE was increased from 24 to 30% and from 14 to 41%, and the linearity was also improved from 0.97 to 0.99 and from 0.75 to 0.99, for GAPD1 and GAPD2, respectively. As expected, the performance of PSPMT based detector did not change. The flood histogram of 12 × 12 array PET detector modules using 3 mm light guide coupled with GAPDs was obtained by simulation, and all crystals of 1 × 1 × 20 mm(3) size were clearly identified. PET detector module coupled with thick light guide and GAPD array with large-area microcells was proposed to obtain high QE and high spatial resolution, and its feasibility was verified. This study demonstrated that the overall PET performance of the proposed design was considerably improved, and this approach will provide opportunities to develop GAPD based PET detector with a high LCE. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Measurement of Total Scatter Factor for Stereotactic Cones with Plastic Scintillation Detector

PubMed Central

Chaudhari, Suresh H; Dobhal, Rishabh; Kinhikar, Rajesh A.; Kadam, Sudarshan S.; Deshpande, Deepak D.

2017-01-01

Advanced radiotherapy modalities such as stereotactic radiosurgery (SRS) and image-guided radiotherapy may employ very small beam apertures for accurate localized high dose to target. Accurate measurement of small radiation fields is a well-known challenge for many dosimeters. The purpose of this study was to measure total scatter factors for stereotactic cones with plastic scintillation detector and its comparison against diode detector and theoretical estimates. Measurements were performed on Novalis Tx™ linear accelerator for 6MV SRS beam with stereotactic cones of diameter 6 mm, 7.5 mm, 10 mm, 12.5 mm, and 15 mm. The advantage of plastic scintillator detector is in its energy dependence. The total scatter factor was measured in water at the depth of dose maximum. Total scatter factor with plastic scintillation detector was determined by normalizing the readings to field size of 10 cm × 10 cm. To overcome energy dependence of diode detector for the determination of scatter factor with diode detector, daisy chaining method was used. The plastic scintillator detector was calibrated against the ionization chamber, and the reproducibility in the measured doses was found to be within ± 1%. Total scatter factor measured with plastic scintillation detector was 0.728 ± 0.3, 0.783 ± 0.05, 0.866 ± 0.55, 0.885 ± 0.5, and 0.910 ± 0.06 for cone sizes of 6 mm, 7.5 mm, 10 mm, 12.5 mm, and 15 mm, respectively. Total scatter factor measured with diode detector was 0.733 ± 0.03, 0.782 ± 0.02, 0.834 ± 0.07, 0.854 ± 0.02, and 0.872 ± 0.02 for cone sizes of 6 mm, 7.5 mm, 10 mm, 12.5 mm, and 15 mm, respectively. The variation in the measurement of total scatter factor with published Monte Carlo data was found to be −1.3%, 1.9%, −0.4%, and 0.4% for cone sizes of 7.5 mm, 10 mm, 12.5 mm, and 15 mm, respectively. We conclude that total scatter factor measurements for stereotactic cones can be adequately carried out with a plastic scintillation detector. Our results show a high level of consistency within our data and compared well with published data. PMID:28405102

Measurement of Total Scatter Factor for Stereotactic Cones with Plastic Scintillation Detector.

PubMed

Chaudhari, Suresh H; Dobhal, Rishabh; Kinhikar, Rajesh A; Kadam, Sudarshan S; Deshpande, Deepak D

2017-01-01

Advanced radiotherapy modalities such as stereotactic radiosurgery (SRS) and image-guided radiotherapy may employ very small beam apertures for accurate localized high dose to target. Accurate measurement of small radiation fields is a well-known challenge for many dosimeters. The purpose of this study was to measure total scatter factors for stereotactic cones with plastic scintillation detector and its comparison against diode detector and theoretical estimates. Measurements were performed on Novalis Tx ™ linear accelerator for 6MV SRS beam with stereotactic cones of diameter 6 mm, 7.5 mm, 10 mm, 12.5 mm, and 15 mm. The advantage of plastic scintillator detector is in its energy dependence. The total scatter factor was measured in water at the depth of dose maximum. Total scatter factor with plastic scintillation detector was determined by normalizing the readings to field size of 10 cm × 10 cm. To overcome energy dependence of diode detector for the determination of scatter factor with diode detector, daisy chaining method was used. The plastic scintillator detector was calibrated against the ionization chamber, and the reproducibility in the measured doses was found to be within ± 1%. Total scatter factor measured with plastic scintillation detector was 0.728 ± 0.3, 0.783 ± 0.05, 0.866 ± 0.55, 0.885 ± 0.5, and 0.910 ± 0.06 for cone sizes of 6 mm, 7.5 mm, 10 mm, 12.5 mm, and 15 mm, respectively. Total scatter factor measured with diode detector was 0.733 ± 0.03, 0.782 ± 0.02, 0.834 ± 0.07, 0.854 ± 0.02, and 0.872 ± 0.02 for cone sizes of 6 mm, 7.5 mm, 10 mm, 12.5 mm, and 15 mm, respectively. The variation in the measurement of total scatter factor with published Monte Carlo data was found to be -1.3%, 1.9%, -0.4%, and 0.4% for cone sizes of 7.5 mm, 10 mm, 12.5 mm, and 15 mm, respectively. We conclude that total scatter factor measurements for stereotactic cones can be adequately carried out with a plastic scintillation detector. Our results show a high level of consistency within our data and compared well with published data.

The Generalized Centroid Difference method for lifetime measurements via γ-γ coincidences using large fast-timing arrays

NASA Astrophysics Data System (ADS)

Régis, J.-M.; Jolie, J.; Mach, H.; Simpson, G. S.; Blazhev, A.; Pascovici, G.; Pfeiffer, M.; Rudigier, M.; Saed-Samii, N.; Warr, N.; Blanc, A.; de France, G.; Jentschel, M.; Köster, U.; Mutti, P.; Soldner, T.; Ur, C. A.; Urban, W.; Bruce, A. M.; Drouet, F.; Fraile, L. M.; Ilieva, S.; Korten, W.; Kröll, T.; Lalkovski, S.; Mărginean, S.; Paziy, V.; Podolyák, Zs.; Regan, P. H.; Stezowski, O.; Vancraeyenest, A.

2015-05-01

A novel method for direct electronic "fast-timing" lifetime measurements of nuclear excited states via γ-γ coincidences using an array equipped with N very fast high-resolution LaBr3(Ce) scintillator detectors is presented. The generalized centroid difference method provides two independent "start" and "stop" time spectra obtained without any correction by a superposition of the N(N - 1)/2 calibrated γ-γ time difference spectra of the N detector fast-timing system. The two fast-timing array time spectra correspond to a forward and reverse gating of a specific γ-γ cascade and the centroid difference as the time shift between the centroids of the two time spectra provides a picosecond-sensitive mirror-symmetric observable of the set-up. The energydependent mean prompt response difference between the start and stop events is calibrated and used as a single correction for lifetime determination. These combined fast-timing array mean γ-γ zero-time responses can be determined for 40 keV < Eγ < 1.4 MeV with a precision better than 10 ps using a 152Eu γ-ray source. The new method is described with examples of (n,γ) and (n,f,γ) experiments performed at the intense cold-neutron beam facility PF1B of the Institut Laue-Langevin in Grenoble, France, using 16 LaBr3(Ce) detectors within the EXILL&FATIMA campaign in 2013. The results are discussed with respect to possible systematic errors induced by background contributions.

Borehole Muon Detector Development

NASA Astrophysics Data System (ADS)

Bonneville, A.; Flygare, J.; Kouzes, R.; Lintereur, A.; Yamaoka, J. A. K.; Varner, G. S.

2015-12-01

Increasing atmospheric CO2 concentrations have spurred investigation into carbon sequestration methods. One of the possibilities being considered, storing super-critical CO2 in underground reservoirs, has drawn more attention and pilot projects are being supported worldwide. Monitoring of the post-injection fate of CO2 is of utmost importance. Generally, monitoring options are active methods, such as 4D seismic reflection or pressure measurements in monitoring wells. We propose here to develop a 4-D density tomography of subsurface CO2 reservoirs using cosmic-ray muon detectors deployed in a borehole. Muon detection is a relatively mature field of particle physics and there are many muon detector designs, though most are quite large and not designed for subsurface measurements. The primary technical challenge preventing deployment of this technology in the subsurface is the lack of miniaturized muon-tracking detectors capable of fitting in standard boreholes and that will resist the harsh underground conditions. A detector with these capabilities is being developed by a collaboration supported by the U.S. Department of Energy. Current simulations based on a Monte Carlo modeling code predict that the incoming muon angle can be resolved with an error of approximately two degrees, using either underground or sea level spectra. The robustness of the design comes primarily from the use of scintillating rods as opposed to drift tubes. The rods are arrayed in alternating layers to provide a coordinate scheme. Preliminary testing and measurements are currently being performed to test and enhance the performance of the scintillating rods, in both a laboratory and a shallow underground facility. The simulation predictions and data from the experiments will be presented.

High efficiency CsI(Tl)/HgI{sub 2} gamma ray spectrometers

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

Wang, Y.J.; Patt, B.E.; Iwanczyk, J.S.

CsI(Tl)/HgI{sub 2} gamma-ray spectrometers have been constructed using 0.5 inch diameter detectors which show excellent energy resolution: 4.58% FWHM for 662 keV {sup 137}Cs gamma-ray photons. Further efforts have been focused on optimization of larger size ({ge} 1 inch diameter) detector structures and improvement of low noise electronics. In order to take full advantage of scintillation detectors for high energy gamma-rays, larger scintillators are always preferred for their higher detection efficiencies. However, the larger capacitance and higher dark current caused by the larger size of the detector could result in a higher FWHM resolution. Also, the increased probability of includingmore » nonuniformities in larger pieces of crystals makes it more difficult to obtain the high resolutions one obtains from small detectors. Thus for very large volume scintillators, it may be necessary to employ a photodiode (PD) with a sensitive area smaller than the cross-section of the scintillator. Monte Carlo simulations of the light collection for various tapered scintillator/PD configuration were performed in order to find those geometries which resulted in the best light collection. According to the simulation results, scintillators with the most favorable geometry, the conical frustum, have been fabricated and evaluated. The response of a large conical frustum (top-2 inch, bottom-1 inch, 2 inch high) CsI(Tl) scintillator coupled with a 1 inch HgI{sub 2} PD was measured. The energy resolution of the 662 keV peak was 5.57%. The spectrum shows much higher detection efficiency than those from smaller scintillators, i.e., much higher peak-to-Compton ratio in the spectrum.« less

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.

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.

Development of neutron-monitor detector using liquid organic scintillator coupled with 6Li + ZnS(Ag) Sheet.

PubMed

Sato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Takahashi, Fumiaki

2004-01-01

A phoswitch-type detector has been developed for monitoring neutron doses in high-energy accelerator facilities. The detector is composed of a liquid organic scintillator (BC501A) coupled with ZnS(Ag) sheets doped with 6Li. The dose from neutrons with energies above 1 MeV is evaluated from the light output spectrum of the BC501A by applying the G-function, which relates the spectrum to the neutron dose directly. The dose from lower energy neutrons, on the other hand, is estimated from the number of scintillations emitted from the ZnS(Ag) sheets. Characteristics of the phoswitch-type detector were studied experimentally in some neutron fields. It was found from the experiments that the detector has an excellent property of pulse-shape discrimination between the scintillations of BC501A and the ZnS(Ag) sheets. The experimental results also indicate that the detector is capable of reproducing doses from thermal neutrons as well as neutrons with energies from one to several tens of megaelectronvolts (MeV).

Monte Carlo simulations and measurements for efficiency determination of lead shielded plastic scintillator detectors

NASA Astrophysics Data System (ADS)

Yasin, Zafar; Negoita, Florin; Tabbassum, Sana; Borcea, Ruxandra; Kisyov, Stanimir

2017-12-01

The plastic scintillators are used in different areas of science and technology. One of the use of these scintillator detectors is as beam loss monitors (BLM) for new generation of high intensity heavy ion in superconducting linear accelerators. Operated in pulse counting mode with rather high thresholds and shielded by few centimeters of lead in order to cope with radiofrequency noise and X-ray background emitted by accelerator cavities, they preserve high efficiency for high energy gamma ray and neutrons produced in the nuclear reactions of lost beam particles with accelerator components. Efficiency calculation and calibration of detectors is very important before their practical usage. In the present work, the efficiency of plastic scintillator detectors is simulated using FLUKA for different gamma and neutron sources like, 60Co, 137Cs and 238Pu-Be. The sources are placed at different positions around the detector. Calculated values are compared with the measured values and a reasonable agreement is observed.

Understanding the SNO+ Detector

DOE PAGES

Kamdin, K.

2015-03-24

SNO+, a large liquid scintillator experiment, is the successor of the Sudbury Neutrino Observatory (SNO) experiment. The scintillator volume will be loaded with large quantities of 130Te, an isotope that undergoes double beta decay, in order to search for neutrinoless double beta decay. In addition to this search, SNO+ has a broad physics program due to its sensitivity to solar and supernova neutrinos, as well as reactor and geo anti-neutrinos. SNO+ can also place competitive limits on certain modes of invisible nucleon decay during its first phase. The detector is currently undergoing commissioning in preparation for its first phase, inmore » which the detector is filled with ultra pure water. This will be followed by a pure scintillator phase, and then a Tellurium-loaded scintillator phase to search for neutrinoless double beta decay. Here we present the work done to model detector aging, which was first observed during SNO. The aging was found to reduce the optical response of the detector. We also describe early results from electronics calibration of SNO+.« less

Physics considerations in MV-CBCT multi-layer imager design.

PubMed

Hu, Yue-Houng; Fueglistaller, Rony; Myronakis, Marios E; Rottmann, Joerg; Wang, Adam; Shedlock, Daniel; Morf, Daniel; Baturin, Paul; Huber, Pascal; Star-Lack, Josh M; Berbeco, Ross I

2018-05-30

Megavoltage (MV) cone-beam computed tomography (CBCT) using an electronic portal imaging (EPID) offers advantageous features, including 3D mapping, treatment beam registration, high-z artifact suppression, and direct radiation dose calculation. Adoption has been slowed by image quality limitations and concerns about imaging dose. Developments in imager design, including pixelated scintillators, structured phosphors, inexpensive scintillation materials, and multi-layer imager (MLI) architecture have been explored to improve EPID image quality and reduce imaging dose. The present study employs a hybrid Monte Carlo and linear systems model to determine the effect of detector design elements, such as multi-layer architecture and scintillation materials. We follow metrics of image quality including modulation transfer function (MTF) and noise power spectrum (NPS) from projection images to 3D reconstructions to in-plane slices and apply a task based figure-of-merit, the ideal observer signal-to-noise ratio (d') to determine the effect of detector design on object detectability. Generally, detectability was limited by detector noise performance. Deploying an MLI imager with a single scintillation material for all layers yields improvement in noise performance and d' linear with the number of layers. In general, improving x-ray absorption using thicker scintillators results in improved DQE(0). However, if light yield is low, performance will be affected by electronic noise at relatively high doses, resulting in rapid image quality degradation. Maximizing image quality in a heterogenous MLI detector (i.e. multiple different scintillation materials) is most affected by limiting imager noise. However, while a second-order effect, maximizing total spatial resolution of the MLI detector is a balance between the intensity contribution of each layer against its individual MTF. So, while a thinner scintillator may yield a maximal individual-layer MTF, its quantum efficiency will be relatively low in comparison to a thicker scintillator and thus, intensity contribution may be insufficient to noticeably improve the total detector MTF. © 2018 Institute of Physics and Engineering in Medicine.

Positron emission tomography wrist detector

DOEpatents

Schlyer, David J.; O'Connor, Paul; Woody, Craig; Junnarkar, Sachin Shrirang; Radeka, Veljko; Vaska, Paul; Pratte, Jean-Francois

2006-08-15

A method of serially transferring annihilation information in a compact positron emission tomography (PET) scanner includes generating a time signal representing a time-of-occurrence of an annihilation event, generating an address signal representing a channel detecting the annihilation event, and generating a channel signal including the time and address signals. The method also includes generating a composite signal including the channel signal and another similarly generated channel signal concerning another annihilation event. An apparatus that serially transfers annihilation information includes a time signal generator, address signal generator, channel signal generator, and composite signal generator. The time signal is asynchronous and the address signal is synchronous to a clock signal. A PET scanner includes a scintillation array, detection array, front-end array, and a serial encoder. The serial encoders include the time signal generator, address signal generator, channel signal generator, and composite signal generator.

Temperature dependence of alpha-induced scintillation in the 1,1,4,4-tetraphenyl-1,3-butadiene wavelength shifter

NASA Astrophysics Data System (ADS)

Veloce, L. M.; Kuźniak, M.; Di Stefano, P. C. F.; Noble, A. J.; Boulay, M. G.; Nadeau, P.; Pollmann, T.; Clark, M.; Piquemal, M.; Schreiner, K.

2016-06-01

Liquid noble based particle detectors often use the organic wavelength shifter 1,1,4,4-tetraphenyl-1,3-butadiene (TPB) which shifts UV scintillation light to the visible regime, facilitating its detection, but which also can scintillate on its own. Dark matter searches based on this type of detector commonly rely on pulse-shape discrimination (PSD) for background mitigation. Alpha-induced scintillation therefore represents a possible background source in dark matter searches. The timing characteristics of this scintillation determine whether this background can be mitigated through PSD. We have therefore characterized the pulse shape and light yield of alpha induced TPB scintillation at temperatures ranging from 300 K down to 4 K, with special attention given to liquid noble gas temperatures. We find that the pulse shapes and light yield depend strongly on temperature. In addition, the significant contribution of long time constants above ~50 K provides an avenue for discrimination between alpha decay events in TPB and nuclear-recoil events in noble liquid detectors.

Effects of detector-source distance and detector bias voltage variations on time resolution of general purpose plastic scintillation detectors.

PubMed

Ermis, E E; Celiktas, C

2012-12-01

Effects of source-detector distance and the detector bias voltage variations on time resolution of a general purpose plastic scintillation detector such as BC400 were investigated. (133)Ba and (207)Bi calibration sources with and without collimator were used in the present work. Optimum source-detector distance and bias voltage values were determined for the best time resolution by using leading edge timing method. Effect of the collimator usage on time resolution was also investigated. Copyright © 2012 Elsevier Ltd. All rights reserved.

Ultrahigh-resolution CT and DR scanner

NASA Astrophysics Data System (ADS)

DiBianca, Frank A.; Gupta, Vivek; Zou, Ping; Jordan, Lawrence M.; Laughter, Joseph S.; Zeman, Herbert D.; Sebes, Jeno I.

1999-05-01

A new technique called Variable-Resolution X-ray (VRX) detection that dramatically increases the spatial resolution in computed tomography (CT) and digital radiography (DR) is presented. The technique is based on a principle called 'projective compression' that allows the resolution element of a CT detector to scale with the subject or field size. For very large (40 - 50 cm) field sizes, resolution exceeding 2 cy/mm is possible and for very small fields, microscopy is attainable with resolution exceeding 100 cy/mm. Several effects that could limit the performance of VRX detectors are considered. Experimental measurements on a 16-channel, CdWO4 scintillator + photodiode test array yield a limiting MTF of 64 cy/mm (8(mu) ) in the highest-resolution configuration reported. Preliminary CT images have been made of small anatomical specimens and small animals using a storage phosphor screen in the VRX mode. Measured detector resolution of the CT projection data exceeds 20 cy/mm (less than 25 (mu) ); however, the final, reconstructed CT images produced thus far exhibit 10 cy/mm (50 (mu) ) resolution because of non-flatness of the storage phosphor plates, focal spot effects and the use of a rudimentary CT reconstruction algorithm. A 576-channel solid-state detector is being fabricated that is expected to achieve CT image resolution in excess of that of the 26-channel test array.

Upgrade of Tile Calorimeter of the ATLAS Detector for the High Luminosity LHC.

NASA Astrophysics Data System (ADS)

Valdes Santurio, Eduardo; Tile Calorimeter System, ATLAS

2017-11-01

The Tile Calorimeter (TileCal) is the hadronic calorimeter of ATLAS covering the central region of the ATLAS experiment. TileCal is a sampling calorimeter with steel as absorber and scintillators as active medium. The scintillators are read out by wavelength shifting fibers coupled to photomultiplier tubes (PMT). The analogue signals from the PMTs are amplified, shaped and digitized by sampling the signal every 25 ns. The High Luminosity Large Hadron Collider (HL-LHC) will have a peak luminosity of 5 × 1034 cm -2 s -1, five times higher than the design luminosity of the LHC. TileCal will undergo a major replacement of its on- and off-detector electronics for the high luminosity programme of the LHC in 2026. The calorimeter signals will be digitized and sent directly to the off-detector electronics, where the signals are reconstructed and shipped to the first level of trigger at a rate of 40 MHz. This will provide a better precision of the calorimeter signals used by the trigger system and will allow the development of more complex trigger algorithms. Three different options are presently being investigated for the front-end electronic upgrade. Extensive test beam studies will determine which option will be selected. Field Programmable Gate Arrays (FPGAs) are extensively used for the logic functions of the off- and on-detector electronics. One hybrid demonstrator prototype module with the new calorimeter module electronics, but still compatible with the present system, may be inserted in ATLAS at the end of 2016.

Development of a Compton camera for prompt-gamma medical imaging

NASA Astrophysics Data System (ADS)

Aldawood, S.; Thirolf, P. G.; Miani, A.; Böhmer, M.; Dedes, G.; Gernhäuser, R.; Lang, C.; Liprandi, S.; Maier, L.; Marinšek, T.; Mayerhofer, M.; Schaart, D. R.; Lozano, I. Valencia; Parodi, K.

2017-11-01

A Compton camera-based detector system for photon detection from nuclear reactions induced by proton (or heavier ion) beams is under development at LMU Munich, targeting the online range verification of the particle beam in hadron therapy via prompt-gamma imaging. The detector is designed to be capable to reconstruct the photon source origin not only from the Compton scattering kinematics of the primary photon, but also to allow for tracking of the secondary Compton-scattered electrons, thus enabling a γ-source reconstruction also from incompletely absorbed photon events. The Compton camera consists of a monolithic LaBr3:Ce scintillation crystal, read out by a multi-anode PMT acting as absorber, preceded by a stacked array of 6 double-sided silicon strip detectors as scatterers. The detector components have been characterized both under offline and online conditions. The LaBr3:Ce crystal exhibits an excellent time and energy resolution. Using intense collimated 137Cs and 60Co sources, the monolithic scintillator was scanned on a fine 2D grid to generate a reference library of light amplitude distributions that allows for reconstructing the photon interaction position using a k-Nearest Neighbour (k-NN) algorithm. Systematic studies were performed to investigate the performance of the reconstruction algorithm, revealing an improvement of the spatial resolution with increasing photon energy to an optimum value of 3.7(1)mm at 1.33 MeV, achieved with the Categorical Average Pattern (CAP) modification of the k-NN algorithm.

Geometry Survey of the Time-of-Flight Neutron-Elastic Scattering (Antonella) Experiment

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

Oshinowo, Babatunde O.; Izraelevitch, Federico

The Antonella experiment is a measurement of the ionization efficiency of nuclear recoils in silicon at low energies [1]. It is a neutron elastic scattering experiment motivated by the search for dark matter particles. In this experiment, a proton beam hits a lithium target and neutrons are produced. The neutron shower passes through a collimator that produces a neutron beam. The beam illuminates a silicon detector. With a certain probability, a neutron interacts with a silicon nucleus of the detector producing elastic scattering. After the interaction, a fraction of the neutron energy is transferred to the silicon nucleus which acquiresmore » kinetic energy and recoils. This kinetic energy is then dissipated in the detector producing ionization and thermal energy. The ionization produced is measured with the silicon detector electronics. On the other hand, the neutron is scattered out of the beam. A neutron-detector array (made of scintillator bars) registers the neutron arrival time and the scattering angle to reconstruct the kinematics of the neutron-nucleus interaction with the time-of-flight technique [2]. In the reconstruction equations, the energy of the nuclear recoil is a function of the scattering angle with respect to the beam direction, the time-of-flight of the neutron and the geometric distances between components of the setup (neutron-production target, silicon detector, scintillator bars). This paper summarizes the survey of the different components of the experiment that made possible the off-line analysis of the collected data. Measurements were made with the API Radian Laser Tracker and I-360 Probe Wireless. The survey was completed at the University of Notre Dame, Indiana, USA in February 2015.« less

Development of signal processing system of avalanche photo diode for space observations by Astro-H

NASA Astrophysics Data System (ADS)

Ohno, M.; Goto, K.; Hanabata, Y.; Takahashi, H.; Fukazawa, Y.; Yoshino, M.; Saito, T.; Nakamori, T.; Kataoka, J.; Sasano, M.; Torii, S.; Uchiyama, H.; Nakazawa, K.; Watanabe, S.; Kokubun, M.; Ohta, M.; Sato, T.; Takahashi, T.; Tajima, H.

2013-01-01

Astro-H is the sixth Japanese X-ray space observatory which will be launched in 2014. Two of onboard instruments of Astro-H, Hard X-ray Imager and Soft Gamma-ray Detector are surrounded by many number of large Bismuth Germanate (Bi4Ge3O12; BGO) scintillators. Optimum readout system of scintillation lights from these BGOs are essential to reduce the background signals and achieve high performance for main detectors because most of gamma-rays from out of field-of-view of main detectors or radio-isotopes produced inside them due to activation can be eliminated by anti-coincidence technique using BGO signals. We apply Avalanche Photo Diode (APD) for light sensor of these BGO detectors since their compactness and high quantum efficiency make it easy to design such large number of BGO detector system. For signal processing from APDs, digital filter and other trigger logics on the Field-Programmable Gate Array (FPGA) is used instead of discrete analog circuits due to limitation of circuit implementation area on spacecraft. For efficient observations, we have to achieve as low threshold of anti-coincidence signal as possible by utilizing the digital filtering. In addition, such anti-coincident signals should be sent to the main detector within 5 μs to make it in time to veto the A-D conversion. Considering this requirement and constraint from logic size of FPGA, we adopt two types of filter, 8 delay taps filter with only 2 bit precision coefficient and 16 delay taps filter with 8 bit precision coefficient. The data after former simple filter provides anti-coincidence signal quickly in orbit, and the latter filter is used for detail analysis after the data is down-linked.

A scintillating gas detector for 2D dose measurements in clinical carbon beams.

PubMed

Seravalli, E; de Boer, M; Geurink, F; Huizenga, J; Kreuger, R; Schippers, J M; van Eijk, C W E; Voss, B

2008-09-07

A two-dimensional position sensitive dosimetry system based on a scintillating gas detector has been developed for pre-treatment verification of dose distributions in hadron therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside which two cascaded gas electron multipliers (GEMs) are mounted. A GEM is a thin kapton foil with copper cladding structured with a regular pattern of sub-mm holes. The primary electrons, created in the detector's sensitive volume by the incoming beam, drift in an electric field towards the GEMs and undergo gas multiplication in the GEM holes. During this process, photons are emitted by the excited Ar/CF4 gas molecules and detected by a mirror-lens-CCD camera system. Since the amount of emitted light is proportional to the dose deposited in the sensitive volume of the detector by the incoming beam, the intensity distribution of the measured light spot is proportional to the 2D hadron dose distribution. For a measurement of a 3D dose distribution, the scintillating gas detector is mounted at the beam exit side of a water-bellows phantom, whose thickness can be varied in steps. In this work, the energy dependence of the output signal of the scintillating gas detector has been verified in a 250 MeV/u clinical 12C ion beam by means of a depth-dose curve measurement. The underestimation of the measured signal at the Bragg peak depth is only 9% with respect to an air-filled ionization chamber. This is much smaller than the underestimation found for a scintillating Gd2O2S:Tb ('Lanex') screen under the same measurement conditions (43%). Consequently, the scintillating gas detector is a promising device for verifying dose distributions in high LET beams, for example to check hadron therapy treatment plans which comprise beams with different energies.

A scintillating gas detector for 2D dose measurements in clinical carbon beams

NASA Astrophysics Data System (ADS)

Seravalli, E.; de Boer, M.; Geurink, F.; Huizenga, J.; Kreuger, R.; Schippers, J. M.; van Eijk, C. W. E.; Voss, B.

2008-09-01

A two-dimensional position sensitive dosimetry system based on a scintillating gas detector has been developed for pre-treatment verification of dose distributions in hadron therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside which two cascaded gas electron multipliers (GEMs) are mounted. A GEM is a thin kapton foil with copper cladding structured with a regular pattern of sub-mm holes. The primary electrons, created in the detector's sensitive volume by the incoming beam, drift in an electric field towards the GEMs and undergo gas multiplication in the GEM holes. During this process, photons are emitted by the excited Ar/CF4 gas molecules and detected by a mirror-lens-CCD camera system. Since the amount of emitted light is proportional to the dose deposited in the sensitive volume of the detector by the incoming beam, the intensity distribution of the measured light spot is proportional to the 2D hadron dose distribution. For a measurement of a 3D dose distribution, the scintillating gas detector is mounted at the beam exit side of a water-bellows phantom, whose thickness can be varied in steps. In this work, the energy dependence of the output signal of the scintillating gas detector has been verified in a 250 MeV/u clinical 12C ion beam by means of a depth-dose curve measurement. The underestimation of the measured signal at the Bragg peak depth is only 9% with respect to an air-filled ionization chamber. This is much smaller than the underestimation found for a scintillating Gd2O2S:Tb ('Lanex') screen under the same measurement conditions (43%). Consequently, the scintillating gas detector is a promising device for verifying dose distributions in high LET beams, for example to check hadron therapy treatment plans which comprise beams with different energies.

New concepts for HgI2 scintillator gamma ray spectroscopy

NASA Technical Reports Server (NTRS)

Iwanczyk, Jan S.

1994-01-01

The primary goals of this project are development of the technology for HgI2 photodetectors (PD's), development of a HgI2/scintillator gamma detector, development of electronics, and development of a prototype gamma spectrometer. Work on the HgI2 PD's involved HgI2 purification and crystal growth, detector surface and electrical contact studies, PD structure optimization, encapsulation and packaging, and testing. Work on the HgI2/scintillator gamma detector involved a study of the optical - mechanical coupling for the optimization of CsI(Tl)/HgI2 gamma ray detectors and determination of the relationship between resolution versus scintillator type and size. The development of the electronics focused on low noise amplification circuits using different preamp input FET's and the use of a coincidence technique to maximize the signal, minimize the noise contribution in the gamma spectra, and improve the overall system resolution.

A 32 mm  ×  32 mm  ×  22 mm monolithic LYSO:Ce detector with dual-sided digital photon counter readout for ultrahigh-performance TOF-PET and TOF-PET/MRI

NASA Astrophysics Data System (ADS)

Borghi, Giacomo; Peet, Bart Jan; Tabacchini, Valerio; Schaart, Dennis R.

2016-07-01

New applications for positron emission tomography (PET) and combined PET/magnetic resonance imaging (MRI) are currently emerging, for example in the fields of neurological, breast, and pediatric imaging. Such applications require improved image quality, reduced dose, shorter scanning times, and more precise quantification. This can be achieved by means of dedicated scanners based on ultrahigh-performance detectors, which should provide excellent spatial resolution, precise depth-of-interaction (DOI) estimation, outstanding time-of-flight (TOF) capability, and high detection efficiency. Here, we introduce such an ultrahigh-performance TOF/DOI PET detector, based on a 32 mm  ×  32 mm  ×  22 mm monolithic LYSO:Ce crystal. The 32 mm  ×  32 mm front and back faces of the crystal are coupled to a digital photon counter (DPC) array, in so-called dual-sided readout (DSR) configuration. The fully digital detector offers a spatial resolution of ~1.1 mm full width at half maximum (FWHM)/~1.2 mm mean absolute error, together with a DOI resolution of ~2.4 mm FWHM, an energy resolution of 10.2% FWHM, and a coincidence resolving time of 147 ps FWHM. The time resolution closely approaches the best results (135 ps FWHM) obtained to date with small crystals made from the same material coupled to the same DPC arrays, illustrating the excellent correction for optical and electronic transit time spreads that can be achieved in monolithic scintillators using maximum-likelihood techniques for estimating the time of interaction. The performance barely degrades for events with missing data (up to 6 out of 32 DPC dies missing), permitting the use of almost all events registered under realistic acquisition conditions. Moreover, the calibration procedures and computational methods used for position and time estimation follow recently made improvements that make them fast and practical, opening up realistic perspectives for using DSR monolithic scintillator detectors in TOF-PET and TOF-PET/MRI systems.

A PET detector prototype based on digital SiPMs and GAGG scintillators.

PubMed

Schneider, Florian R; Shimazoe, Kenji; Somlai-Schweiger, Ian; Ziegler, Sibylle I

2015-02-21

Silicon Photomultipliers (SiPM) are interesting light sensors for Positron Emission Tomography (PET). The detector signal of analog SiPMs is the total charge of all fired cells. Energy and time information have to be determined with dedicated readout electronics. Philips Digital Photon Counting has developed a SiPM with added electronics on cell level delivering a digital value of the time stamp and number of fired cells. These so called Digital Photon Counters (DPC) are fully digital devices. In this study, the feasibility of using DPCs in combination with LYSO (Lutetium Yttrium Oxyorthosilicate) and GAGG (Gadolinium Aluminum Gallium Garnet) scintillators for PET is tested. Each DPC module has 64 channels with 3.2 × 3.8775 mm(2), comprising 3200 cells each. GAGG is a recently developed scintillator (Zeff = 54, 6.63 g cm(-3), 520 nm peak emission, 46 000 photons MeV(-1), 88 ns (92%) and 230 ns (8%) decay times, non-hygroscopic, chemically and mechanically stable). Individual crystals of 2 × 2 × 6 mm(3) were coupled onto each DPC pixel. LYSO coupled to the DPC results in a coincidence time resolution (CTR) of 171 ps FWHM and an energy resolution of 12.6% FWHM at 511 keV. Using GAGG, coincidence timing is 310 ps FWHM and energy resolution is 8.5% FWHM. A PET detector prototype with 2 DPCs equipped with a GAGG array matching the pixel size (3.2 × 3.8775 × 8 mm(3)) was assembled. To emulate a ring of 10 modules, objects are rotated in the field of view. CTR of the PET is 619 ps and energy resolution is 9.2% FWHM. The iterative MLEM reconstruction is based on system matrices calculated with an analytical detector response function model. A phantom with rods of different diameters filled with (18)F was used for tomographic tests.

A PET detector prototype based on digital SiPMs and GAGG scintillators

NASA Astrophysics Data System (ADS)

Schneider, Florian R.; Shimazoe, Kenji; Somlai-Schweiger, Ian; Ziegler, Sibylle I.

2015-02-01

Silicon Photomultipliers (SiPM) are interesting light sensors for Positron Emission Tomography (PET). The detector signal of analog SiPMs is the total charge of all fired cells. Energy and time information have to be determined with dedicated readout electronics. Philips Digital Photon Counting has developed a SiPM with added electronics on cell level delivering a digital value of the time stamp and number of fired cells. These so called Digital Photon Counters (DPC) are fully digital devices. In this study, the feasibility of using DPCs in combination with LYSO (Lutetium Yttrium Oxyorthosilicate) and GAGG (Gadolinium Aluminum Gallium Garnet) scintillators for PET is tested. Each DPC module has 64 channels with 3.2 × 3.8775 mm2, comprising 3200 cells each. GAGG is a recently developed scintillator (Zeff = 54, 6.63 g cm-3, 520 nm peak emission, 46 000 photons MeV-1, 88 ns (92%) and 230 ns (8%) decay times, non-hygroscopic, chemically and mechanically stable). Individual crystals of 2 × 2 × 6 mm3 were coupled onto each DPC pixel. LYSO coupled to the DPC results in a coincidence time resolution (CTR) of 171 ps FWHM and an energy resolution of 12.6% FWHM at 511 keV. Using GAGG, coincidence timing is 310 ps FWHM and energy resolution is 8.5% FWHM. A PET detector prototype with 2 DPCs equipped with a GAGG array matching the pixel size (3.2 × 3.8775 × 8 mm3) was assembled. To emulate a ring of 10 modules, objects are rotated in the field of view. CTR of the PET is 619 ps and energy resolution is 9.2% FWHM. The iterative MLEM reconstruction is based on system matrices calculated with an analytical detector response function model. A phantom with rods of different diameters filled with 18F was used for tomographic tests.

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

Nusrat, Humza; Pang, Geordi; Ahmad, Syed

Purpose: In radiotherapy, the amount of radiation delivered is determined by optimizing the amount of absorbed dose to the tumor. Dose does not always correlate well with the actual biological effects of radiation. This work seeks to validate the LET-dependence of doped plastic scintillators for use in a radiation beam quality (LET) detector. Methods: The LET spectrum ([Φ]) can be resolved knowing the measured signals of uniquely LET-dependent detectors, [S], and the response of each LET-dependent detector to specific LETs ([R]), through the relation [Φ]=[S][R]{sup −1}. Plastic scintillator response is intrinsically LET dependent and can be varied via doping. Initialmore » prototype consists of plastic scintillator and glass taper coupled to an optical fiber; components are housed in black acrylic, reducing effect of ambient light. In order to determine [R], the light response matrix, GEANT4.10.1 Monte Carlo (MC) was used. To validate MC, measurements were done using high energy electrons (9,12,15MeV) and orthovoltage x-rays (100,250kV); scintillator signal was normalized to dose measured simultaneously. Results: Stopping power was varied by changing particle type/energy; measurements indicated that as stopping power increased from 1.9 to 6.6MeV/cm, detector response increased by 263% (+/−29.2%) for 5%Pb-doped scintillator (155% in MC); 52% (+/−7.8%) increase observed when undoped scintillator was used (49% in MC). 5%Pb-doped discrepancy (100kV x-rays) is being investigated. Conclusions: This work validates that doping effects LET/energy response of scintillators; an effect that can be utilized for construction of an LET detector.« less

Gamma-ray detector employing scintillators coupled to semiconductor drift photodetectors

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

Iwanczyk, Jan S.; Patt, Bradley E.

Radiation detectors according to one embodiment of the invention are implemented using scintillators combined with a semiconductor drift photodetectors wherein the components are specifically constructed in terms of their geometry, dimensions, and arrangement so that the scintillator decay time and drift time in the photodetector pairs are matched in order to achieve a greater signal-to-noise ratio. The detectors may include electronics for amplification of electrical signals produced by the silicon drift photodetector, the amplification having a shaping time optimized with respect to the decay time of the scintillator and time spread of the signal in the silicon drift photodetector tomore » substantially maximize the ratio of the signal to the electronic noise.« less

LENS: Prototyping Program

NASA Astrophysics Data System (ADS)

Rountree, S. Derek

2013-04-01

The Low-Energy Neutrino Spectrometer (LENS) prototyping program is broken into two phases. The first of these is μLENS, a small prototype to study the light transmission in the as built LENS scintillation lattice--- a novel detector method of high segmentation in a large liquid scintillation detector. The μLENS prototype is currently deployed and taking data at the Kimballton Underground Research Facility (KURF) near Virginia Tech. I will discuss the Scintillation Lattice construction methods and schemes of the μLENS program for running with minimal channels instrumented to date ˜41 compared to full coverage 216). The second phase of prototyping is the miniLENS detector for which construction is under way. I will discuss the overall design from the miniLENS Scintillation Lattice to the shielding.

High-symmetry organic scintillator systems

DOEpatents

Feng, Patrick L.

2018-02-06

An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based on the pulse shapes of the output signals.

High-symmetry organic scintillator systems

DOEpatents

Feng, Patrick L.

2017-07-18

An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based on the pulse shapes of the output signals.

High-symmetry organic scintillator systems

DOEpatents

Feng, Patrick L.

2017-06-14

An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based on the pulse shapes of the output signals.

High-symmetry organic scintillator systems

DOEpatents

Feng, Patrick L.

2017-09-05

An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based on the pulse shapes of the output signals.

High-symmetry organic scintillator systems

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

Feng, Patrick L.

An ionizing radiation detector or scintillator system includes a scintillating material comprising an organic crystalline compound selected to generate photons in response to the passage of ionizing radiation. The organic compound has a crystalline symmetry of higher order than monoclinic, for example an orthorhombic, trigonal, tetragonal, hexagonal, or cubic symmetry. A photodetector is optically coupled to the scintillating material, and configured to generate electronic signals having pulse shapes based on the photons generated in the scintillating material. A discriminator is coupled to the photon detector, and configured to discriminate between neutrons and gamma rays in the ionizing radiation based onmore » the pulse shapes of the output signals.« less

New concepts for scintillator/HgI[sub 2] gamma ray spectroscopy

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

Wang, Y.J.; Iwanczyk, J.S.; Patt, B.E.

The construction of a high energy resolution gamma ray detector consisting of a scintillator/mercuric iodide photodetector combination has been investigated. Several HgI[sub 2] photodetectors have been fabricated and tested with standard NIM electronics. The energy resolution of a scintillator/HgI[sub 2] pair was found to be 4.75%, full width at half maximum, for 662 keV [sup 137]Cs gamma ray photons. Of five detectors fabricated with the new technique, all produced resolutions better than 5.6% FWHM. This technology makes it possible to reliably produce high quality HgI[sub 2] photodetectors. New design concepts for the HgI[sub 2] photocell, including the transparent entrance electrode,more » detector geometry, and detector packaging, are described in the paper. Advantages of gamma ray spectrometers based upon crystal scintillators optically coupled to HgI[sub 2] photodetectors (in contrast to coupling the scintillators to the more conventional light sensors, i.e., photomultiplier tubes (PMTs)) include greater ruggedness, improved energy resolution, markedly smaller size and weight, reduced power, and insensitivity to magnetic field perturbations.« less

The Cosmic Ray Observatory Project in Nebraska and Public Outreach for the Pierre Auger Observatory in Argentina

NASA Astrophysics Data System (ADS)

Snow, Gregory

2005-04-01

The Cosmic Ray Observatory Project (CROP) is a statewide education and research experiment involving Nebraska high school students, teachers, and college undergraduates in the study of extensive cosmic-ray air showers. A network of high school teams construct, install, and operate school-based detectors in coordination with University of Nebraska physics professors and graduate students. The detector system at each school is an array of scintillation counters recycled from the Chicago Air Shower Array in weather-proof enclosures on the school roof, with a GPS receiver providing a time stamp for cosmic-ray events. The detectors are connected to triggering electronics and a data-acquisition PC inside the building. Students share data via the Internet to search for time coincidences with other sites. CROP has enlisted 26 schools in its first 5 years of operation with the aim of expanding to the 314 high schools in the state over the next several years. The presenter also serves as the Task Leader for Education and Outreach for the Pierre Auger Cosmic Ray Observatory, and selected public outreach activities related to the experiment will be described.

Cryogenic readout techniques for germanium detectors

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

Benato, G.; Cattadori, C.; Di Vacri, A.

High Purity Germanium detectors are used in many applications, from nuclear and astro-particle physics, to homeland security or environment protection. Although quite standard configurations are often used, with cryostats, charge sensitive amplifiers and analog or digital acquisition systems all commercially available, it might be the case that a few specific applications, e.g. satellites, portable devices, cryogenic physics experiments, etc. also require the development of a few additional or complementary techniques. An interesting case is for sure GERDA, the Germanium Detector Array experiment, searching for neutrino-less double beta decay of {sup 76}Ge at the Gran Sasso National Laboratory of INFN -more » Italy. In GERDA the entire detector array, composed of semi-coaxial and BEGe naked crystals, is operated suspended inside a cryostat filled with liquid argon, that acts not only as cooling medium and but also as an active shield, thanks to its scintillation properties. These peculiar circumstances, together with the additional requirement of a very low radioactive background from all the materials adjacent to the detectors, clearly introduce significant constraints on the design of the Ge front-end readout electronics. All the Ge readout solutions developed within the framework of the GERDA collaboration, for both Phase I and Phase II, will be briefly reviewed, with their relative strength and weakness compared together and with respect to ideal Ge readout. Finally, the digital processing techniques developed by the GERDA collaboration for energy estimation of Ge detector signals will be recalled. (authors)« less

Low dose digital X-ray imaging with avalanche amorphous selenium

NASA Astrophysics Data System (ADS)

Scheuermann, James R.; Goldan, Amir H.; Tousignant, Olivier; Léveillé, Sébastien; Zhao, Wei

2015-03-01

Active Matrix Flat Panel Imagers (AMFPI) based on an array of thin film transistors (TFT) have become the dominant technology for digital x-ray imaging. In low dose applications, the performance of both direct and indirect conversion detectors are limited by the electronic noise associated with the TFT array. New concepts of direct and indirect detectors have been proposed using avalanche amorphous selenium (a-Se), referred to as high gain avalanche rushing photoconductor (HARP). The indirect detector utilizes a planar layer of HARP to detect light from an x-ray scintillator and amplify the photogenerated charge. The direct detector utilizes separate interaction (non-avalanche) and amplification (avalanche) regions within the a-Se to achieve depth-independent signal gain. Both detectors require the development of large area, solid state HARP. We have previously reported the first avalanche gain in a-Se with deposition techniques scalable to large area detectors. The goal of the present work is to demonstrate the feasibility of large area HARP fabrication in an a-Se deposition facility established for commercial large area AMFPI. We also examine the effect of alternative pixel electrode materials on avalanche gain. The results show that avalanche gain > 50 is achievable in the HARP layers developed in large area coaters, which is sufficient to achieve x-ray quantum noise limited performance down to a single x-ray photon per pixel. Both chromium (Cr) and indium tin oxide (ITO) have been successfully tested as pixel electrodes.

Large dynamic range radiation detector and methods thereof

DOEpatents

Marrs, Roscoe E [Livermore, CA; Madden, Norman W [Sparks, NV

2012-02-14

According to one embodiment, a radiation detector comprises a scintillator and a photodiode optically coupled to the scintillator. The radiation detector also includes a bias voltage source electrically coupled to the photodiode, a first detector operatively electrically coupled to the photodiode for generating a signal indicative of a level of a charge at an output of the photodiode, and a second detector operatively electrically coupled to the bias voltage source for generating a signal indicative of an amount of current flowing through the photodiode.

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

Gagnon, Jean-Christophe; Theriault, Dany; Guillot, Mathieu

Purpose: To compare the performance of plastic scintillation detectors (PSD) for quality assurance (QA) in stereotactic radiosurgery conditions to a microion-chamber (IC), Gafchromic EBT2 films, 60 008 shielded photon diode (SD) and unshielded diodes (UD), and assess a new 2D crosshair array prototype adapted to small field dosimetry. Methods: The PSD consists of a 1 mm diameter by 1 mm long scintillating fiber (BCF-60, Saint-Gobain, Inc.) coupled to a polymethyl-methacrylate optical fiber (Eska premier, Mitsubishi Rayon Co., Ltd., Tokyo, Japan). Output factors (S{sub c,p}) for apertures used in radiosurgery ranging from 4 to 40 mm in diameter have been measured.more » The PSD crosshair array (PSDCA) is a water equivalent device made up of 49 PSDs contained in a 1.63 cm radius area. Dose profiles measurements were taken for radiosurgery fields using the PSDCA and were compared to other dosimeters. Moreover, a typical stereotactic radiosurgery treatment using four noncoplanar arcs was delivered on a spherical phantom in which UD, IC, or PSD was placed. Using the Xknife planning system (Integra Radionics Burlington, MA), 15 Gy was prescribed at the isocenter, where each detector was positioned. Results: Output Factors measured by the PSD have a mean difference of 1.3% with Gafchromic EBT2 when normalized to a 10 x 10 cm{sup 2} field, and 1.0% when compared with UD measurements normalized to the 35 mm diameter cone. Dose profiles taken with the PSD crosshair array agreed with other single detectors dose profiles in spite of the presence of the 49 PSDs. Gamma values comparing 1D dose profiles obtained with PSD crosshair array with Gafchromic EBT2 and UD measured profiles shows 98.3% and 100.0%, respectively, of detector passing the gamma acceptance criteria of 0.3 mm and 2%. The dose measured by the PSD for a complete stereotactic radiosurgery treatment is comparable to the planned dose corrected for its SD-based S{sub c,p} within 1.4% and 0.7% for 5 and 35 mm diameter cone, respectively. Furthermore, volume averaging of the IC can be observed for the 5 mm aperture where it differs by as much as 9.1% compared to the PSD measurement. The angular dependency of the UD is also observed, unveiled by an under-response around 2.5% of both 5 and 35 mm apertures. Conclusions: Output Factors and dose profiles measurements performed, respectively, with the PSD and the PSDCA were in agreement with those obtained with the UD and EBT2 films. For stereotactic radiosurgery treatment verification, the PSD gives accurate results compared to the planning system and the IC once the latter is corrected to compensate for the averaging effect of the IC. The PSD provides precise results when used as a single detector or in a dense array, resulting in a great potential for stereotactic radiosurgery QA measurements.« less

ZEPLIN-III direct dark matter search : final results and measurements in support of next generation instruments

NASA Astrophysics Data System (ADS)

Reichhart, Lea

2013-12-01

Astrophysical observations give convincing evidence for a vast non-baryonic component, the so-called dark matter, accounting for over 20% of the overall content of our Universe. Direct dark matter search experiments explore the possibility of interactions of these dark matter particles with ordinary baryonic matter via elastic scattering resulting in single nuclear recoils. The ZEPLIN-III detector operated on the basis of a dualphase (liquid/gas) xenon target, recording events in two separate response channels { scintillation and ionisation. These allow discrimination between electron recoils (from background radiation) and the signal expected from Weakly Interacting Massive Particle (WIMP) elastic scatters. Following a productive first exposure, the detector was upgraded with a new array of ultra-low background photomultiplier tubes, reducing the electron recoil background by over an order of magnitude. A second major upgrade to the detector was the incorporation of a tonne-scale active veto detector system, surrounding the WIMP target. Calibration and science data taken in coincidence with ZEPLIN-III showed rejection of up to 30% of the dominant electron recoil background and over 60% of neutron induced nuclear recoils. Data taking for the second science run finished in May 2011 with a total accrued raw fiducial exposure of 1,344 kg days. With this extensive data set, from over 300 days of run time, a limit on the spin-independent WIMP-nucleon cross-section of 4.8 10-8 pb near 50 GeV/c2 WIMP mass with 90% confidence was set. This result combined with the first science run of ZEPLIN-III excludes the scalar cross-section above 3.9 10-8 pb. Studying the background data taken by the veto detector allowed a calculation of the neutron yield induced by high energy cosmic-ray muons in lead of (5.8 0.2) 10-3 neutrons/muon/(g/cm2) for a mean muon energy of 260 GeV. Measurements of this kind are of great importance for large scale direct dark matter search experiments and future rare event searches in general. Finally, this work includes a comprehensive measurement of the energy dependent quenching factor for low energy nuclear recoils in a plastic scintillator, such as from the ZEPLIN-III veto detector, increasing accuracy for future simulation packages featuring large scale plastic scintillator detector systems.

Investigation of the Effect of Temperature and Light Emission from Silicon Photomultiplier Detectors

NASA Astrophysics Data System (ADS)

Ruiz Castruita, Daniel; Ramos, Daniel; Hernandez, Victor; Niduaza, Rommel; Konx, Adrian; Fan, Sewan; Fatuzzo, Laura; Ritt, Stefan

2015-04-01

The silicon photomultiplier (SiPM) is an extremely sensitive light detector capable of measuring very dim light and operates as a photon-number resolving detector. Its high gain comes from operating at slightly above the breakdown voltage, which is also accompanied by a high dark count rate. At this conference poster session we describe our investigation of using SiPMs, the multipixel photon counters (MPPC) from Hamamatsu, as readout detectors for development in a cosmic ray scintillating detector array. Our research includes implementation of a novel design that automatically adjusts for the bias voltage to the MPPC detectors to compensate for changes in the ambient temperature. Furthermore, we describe our investigations for the MPPC detector characteristics at different bias voltages, temperatures and light emission properties. To measure the faint light emitted from the MPPC we use a photomultiplier tube capable of detecting single photons. Our data acquisition setup consists of a 5 Giga sample/second waveform digitizer, the DRS4, triggered to capture the MPPC detector waveforms. Analysis of the digitized waveforms, using the CERN package PAW, would be discussed and presented. US Department of Education Title V Grant PO31S090007.

Measurement of gamma quantum interaction point in plastic scintillator with WLS strips

NASA Astrophysics Data System (ADS)

Smyrski, J.; Alfs, D.; Bednarski, T.; Białas, P.; Czerwiński, E.; Dulski, K.; Gajos, A.; Głowacz, B.; Gupta-Sharma, N.; Gorgol, M.; Jasińska, B.; Kajetanowicz, M.; Kamińska, D.; Korcyl, G.; Kowalski, P.; Krzemień, W.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedźwiecki, Sz.; Pawlik-Niedźwiecka, M.; Raczyński, L.; Rudy, Z.; Salabura, P.; Silarski, M.; Strzelecki, A.; Wieczorek, A.; Wiślicki, W.; Wojnarska, J.; Zgardzińska, B.; Zieliński, M.; Moskal, P.

2017-04-01

The feasibility of measuring the aśxial coordinate of a gamma quantum interaction point in a plastic scintillator bar via the detection of scintillation photons escaping from the scintillator with an array of wavelength-shifting (WLS) strips is demonstrated. Using a test set-up comprising a BC-420 scintillator bar and an array of sixteen BC-482A WLS strips we achieved a spatial resolution of 5 mm (σ) for annihilation photons from a 22Na isotope. The studied method can be used to improve the spatial resolution of a plastic-scintillator-based PET scanner which is being developed by the J-PET collaboration.

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

Volotskova, O; Xu, A; Jozsef, G

Purpose: To investigate the response and dose rate dependence of a scintillation detector over a wide energy range. Methods: The energy dependence of W1 scintillation detector was tested with: 1) 50–225 keV beams generated by an animal irradiator, 2) a Leksell Gamma Knife Perfexion Co-60 source, 3) 6MV, 6FFF, 10FFF and 15MV photon beams, and 4) 6–20MeV electron beams from a linac. Calibrated linac beams were used to deliver 100 cGy to the detector at dmax in water under reference conditions. The gamma-knife measurement was performed in solid water (100 cGy with 16mm collimator). The low energy beams were calibratedmore » with an ion chamber in air (TG-61), and the scintillation detector was placed at the same location as the ionization chamber during calibration. For the linac photon and electron beams, dose rate dependence was tested for 100–2400 and 100–800 MU/min. Results: The scintillation detector demonstrated strong energy dependence in the range of 50–225keV. The measured values were lower than the delivered dose and increased as the energy increased. Therapeutic photon beams showed energy independence with variations less than 1%. Therapeutic electron beams displayed the same sensitivity of ∼2–3% at their corresponding dmax depths. The change in dose-rate of photon and electron beams within the therapeutic energy range did not affect detector output (<0.5%). Measurements acquired with the gamma knife showed that the output data agreed with the delivered dose up to 3%. Conclusion: W1 scintillation detector output has a strong energy dependence in the diagnostic and orthovoltage energy range. Therapeutic photon beams exhibited energy independence with no observable dose-rate dependence. This study may aid in the implementation of a scintillation detector in QA programs by providing energy calibration factors.« less

Measurement and optimization of the light collection uniformity in strongly tapered PWO crystals of the PANDA detector

NASA Astrophysics Data System (ADS)

Diehl, Stefan; Bremer, Daniel; Brinkmann, Kai-Thomas; Dormenev, Valery; Eissner, Tobias; Novotny, Rainer W.; Rosenbaum, Christoph; Zaunick, Hans-Georg; PANDA Collaboration

2017-06-01

The uniformity of the light collection is a crucial parameter for detectors based on inorganic scintillation crystals to guarantee a response proportional to the deposited energy. Especially in case of tapered crystals, like they are widely used to realize a 4π geometry of electromagnetic calorimeters (EMC) in high energy physics experiments, a strong non-uniformity is introduced by an additional focusing of the scintillation light due to the tapered geometry. The paper will discuss the determination and the reduction of the non-uniformity in strongly tapered lead tungstate crystals as used for the construction of the electromagnetic calorimeter of the PANDA detector at the future Facility for Antiproton and Ion Research (FAIR). Among different concepts for an uniformization a single de-polished lateral side face provided the optimum result with a remaining non-uniformity below 5% in good agreement with similar studies for the CMS ECAL at LHC. The impact on the achievable energy resolution in the energy regime of photons below 800 MeV is discussed in detail in comparison to GEANT4 simulations. The comparison of the response of two arrays with polished and de-polished crystals, respectively, shows in the latter case a significant improvement of the constant term of the parametrization of the energy resolution down to 0.5% accompanied by only very slight increase of the statistical term.

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

NASA Astrophysics Data System (ADS)

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

2018-03-01

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

ANAIS: Status and prospects

NASA Astrophysics Data System (ADS)

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

2016-04-01

ANAIS (Annual modulation with NAI Scintillators) experiment aims to look for dark matter annual modulation with 250 kg of ultra-pure NaI(Tl) scintillators at the Canfranc Underground Laboratory (LSC), in order to confirm the DAMA/LIBRA positive signal in a model-independent way. The detector will consists in an array of close-packed single modules, each of them coupled to two high efficiency Hamamatsu photomultipliers. Two 12.5 kg each NaI(Tl) crystals provided by Alpha Spectra are currently taking data at the LSC. These modules have shown an outstanding light collection efficiency (12-16 phe/keV), about the double of that from DAMA/LIBRA phase 1 detectors, which could enable reducing the energy threshold down to 1 keVee. ANAIS crystal radiopurity goals are fulfilled for 232Th and 238U chains, assuming equilibrium, and in the case of 40K, present crystals activity (although not at the required 20 ppb level) could be acceptable. However, a 210Pb contamination out-of-equilibrium has been identified and its origin traced back, so we expect it will be avoided in next prototypes. Finally, current status and prospects of the experiment considering several exposure and background scenarios are presented.

First Tests of a New Fast Waveform Digitizer for PMT Signal Read-out from Liquid Argon Dark Matter Detectors

NASA Astrophysics Data System (ADS)

Szelc, A. M.; Canci, N.; Cavanna, F.; Cortopassi, A.; D'Incecco, M.; Mini, G.; Pietropaolo, F.; Romboli, A.; Segreto, E.; Acciarri, R.

A new generation Waveform Digitizer board as been recently made available on the market by CAEN. The new board CAEN V1751 with 8 Channels per board, 10 bit, 1 GS/s Flash ADC Waveform Digitizer (or 4 channel, 10 bit, 2 GS/s Flash ADC Waveform Digitizer -Dual Edge Sampling mode) with threshold and Auto-Trigger capabilities provides an ideal (relatively low-cost) solution for reading signals from liquid Argon detectors for Dark Matter search equipped with an array of PMTs for the detection of scintillation light. The board was extensively used in real experimental conditions to test its usefulness for possible future uses and to compare it with a state of the art digital oscilloscope. As results, PMT Signal sampling at 1 or 2 GS/s is appropriate for the reconstruction of the fast component of the signal scintillation in Argon (characteristic time of about 4 ns) and the extended dynamic range, after a small customization, allows for the detection of signals in the range of energy needed. The bandwidth is found to be adequate and the intrinsic noise is very low.

Development of InP solid state detector and liquid scintillator containing metal complex for measurement of pp/7Be solar neutrinos and neutrinoless double beta decay

NASA Astrophysics Data System (ADS)

Fukuda, Yoshiyuki; Moriyama, Shigetaka

2012-07-01

A large volume solid state detector using a semi-insulating Indium Phosphide (InP) wafer have been developed for measurement of pp/7Be solar neutrinos. Basic performance such as the charge collection efficiency and the energy resolution were measured by 60% and 20%, respectively. In order to detect two gammas (115keV and 497keV) from neutrino capture, we have designed hybrid detector which consist InP detector and liquid xenon scintillator for IPNOS experiment. New InP detector with thin electrode (Cr 50Å- Au 50Å). For another possibility, an organic liquid scintillator containing indium complex and zirconium complex were studied for a measurement of low energy solar neutrinos and neutrinosless double beta decay, respectively. Benzonitrile was chosen as a solvent because of good solubility for the quinolinolato complexes (2 wt%) and of good light yield for the scintillation induced by gamma-ray irradiation. The photo-luminescence emission spectra of InQ3 and ZrQ4 in benzonitrile was measured and liquid scintillator cocktail using InQ3 and ZrQ4 (50mg) in benzonitrile solutions (20 mL) with secondary scintillators with PPO (100mg) and POPOP (10mg) was made. The energy spectra of incident gammas were measured, and they are first results of the gamma-ray energy spectra using luminescent of metal complexes.

Performance modeling of a wearable brain PET (BET) camera

NASA Astrophysics Data System (ADS)

Schmidtlein, C. R.; Turner, J. N.; Thompson, M. O.; Mandal, K. C.; Häggström, I.; Zhang, J.; Humm, J. L.; Feiglin, D. H.; Krol, A.

2016-03-01

Purpose: To explore, by means of analytical and Monte Carlo modeling, performance of a novel lightweight and low-cost wearable helmet-shaped Brain PET (BET) camera based on thin-film digital Geiger Avalanche Photo Diode (dGAPD) with LSO and LaBr3 scintillators for imaging in vivo human brain processes for freely moving and acting subjects responding to various stimuli in any environment. Methods: We performed analytical and Monte Carlo modeling PET performance of a spherical cap BET device and cylindrical brain PET (CYL) device, both with 25 cm diameter and the same total mass of LSO scintillator. Total mass of LSO in both the BET and CYL systems is about 32 kg for a 25 mm thick scintillator, and 13 kg for 10 mm thick scintillator (assuming an LSO density of 7.3 g/ml). We also investigated a similar system using an LaBr3 scintillator corresponding to 22 kg and 9 kg for the 25 mm and 10 mm thick systems (assuming an LaBr3 density of 5.08 g/ml). In addition, we considered a clinical whole body (WB) LSO PET/CT scanner with 82 cm ring diameter and 15.8 cm axial length to represent a reference system. BET consisted of distributed Autonomous Detector Arrays (ADAs) integrated into Intelligent Autonomous Detector Blocks (IADBs). The ADA comprised of an array of small LYSO scintillator volumes (voxels with base a×a: 1.0 <= a <= 2.0 mm and length c: 3.0 <= c <= 6.0 mm) with 5-65 μm thick reflective layers on its five sides and sixth side optically coupled to the matching array of dGAPDs and processing electronics with total thickness of 50 μm. Simulated energy resolution was 10.8% and 3.3% for LSO and LaBr3 respectively and the coincidence window was set at 2 ns. The brain was simulated as a sphere of uniform F-18 activity with diameter of 10 cm embedded in a center of water sphere with diameter of 10 cm. Results: Analytical and Monte Carlo models showed similar results for lower energy window values (458 keV versus 445 keV for LSO, and 492 keV versus 485 keV for LaBr3), and for the relative performance of system sensitivity. Monte Carlo results further showed that the BET geometry had >50% better noise equivalent count (NEC) performance relative to the CYL geometry, and >1100% better performance than a WB geometry for 25 mm thick LSO and LaBr3. For 10 mm thick LaBr3 equivalent mass systems LSO (7 mm thick) performed ~40% higher NEC than LaBr3. Analytic and Monte Carlo simulations also showed that 1×1×3 mm scintillator crystals can achieve ~1.2 mm FWHM spatial resolution. Conclusions: This study shows that a spherical cap brain PET system can provide improved NEC while preserving spatial resolution when compared to an equivalent dedicated cylindrical PET brain camera and shows greatly improved PET performance relative to a conventional whole body PET/CT. In addition, our simulations show that LSO will generally outperform LaBr3 for NEC unless the timing resolution for LaBr3 is considerably smaller than presently used for LSO, i.e. well below 300 ps.

Development of an ultra-compact CsI/HgI{sub 2} gamma-ray scintillation spectrometer

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

Patt, B.E.; Wang, Y.J.; Iwanczyk, J.S.

A novel new semiconductor photodetector has been developed which utilizes large mercuric iodide photodetectors coupled to highly optimized CsI(T1) scintillators for gamma ray spectroscopy. With this new detector technology the authors have achieved energy resolution superior to that of any other scintillation detector. Furthermore, gamma probes based on the new HgI{sub 2}/CsI(Tl) detector can be highly miniaturized offering improved portability. A {1/2}-inch diameter HgI{sub 2} photodetector coupled with a {1/2}-inch diameter by {1/2}-inch high right-rectangular scintillator produced energy resolution of 4.58% FWHM for {sup 137}Cs (662 keV). This is perhaps the best result ever reported for room temperature scintillation spectroscopy.more » Evaluation of a prototype device with similar performance has been conducted at Los Alamos using Pu and U standard samples. Recently, Monte-Carlo simulations have been performed for co-optimization of the gamma-collection efficiency and light collection efficiency of the scintillator/photodetector pairs resulting in a new tapered scintillator geometry. Energy resolution of 5.69% FWHM at 662 keV was obtained for a 1-inch diameter photodetector coupled to a two-inch long conical CsI(Tl) scintillator; with dimensions: 1-inch diameter at the top tapered to 2-inch diameter at the bottom. The long term stability of the technology has been verified. Current efforts to optimize the detectors for specific applications in safeguards and in materials control and accountability are discussed.« less

Radiation Hardness of dSiPM Sensors in a Proton Therapy Radiation Environment

NASA Astrophysics Data System (ADS)

Diblen, Faruk; Buitenhuis, Tom; Solf, Torsten; Rodrigues, Pedro; van der Graaf, Emiel; van Goethem, Marc-Jan; Brandenburg, Sytze; Dendooven, Peter

2017-07-01

In vivo verification of dose delivery in proton therapy by means of positron emission tomography (PET) or prompt gamma imaging is mostly based on fast scintillation detectors. The digital silicon photomultiplier (dSiPM) allows excellent scintillation detector timing properties and is thus being considered for such verification methods. We present here the results of the first investigation of radiation damage to dSiPM sensors in a proton therapy radiation environment. Radiation hardness experiments were performed at the AGOR cyclotron facility at the KVI-Center for Advanced Radiation Technology, University of Groningen. A 150-MeV proton beam was fully stopped in a water target. In the first experiment, bare dSiPM sensors were placed at 25 cm from the Bragg peak, perpendicular to the beam direction, a geometry typical for an in situ implementation of a PET or prompt gamma imaging device. In the second experiment, dSiPM-based PET detectors containing lutetium yttrium orthosilicate scintillator crystal arrays were placed at 2 and 4 m from the Bragg peak, perpendicular to the beam direction; resembling an in-room PET implementation. Furthermore, the experimental setup was simulated with a Geant4-based Monte Carlo code in order to determine the angular and energy distributions of the neutrons and to determine the 1-MeV equivalent neutron fluences delivered to the dSiPM sensors. A noticeable increase in dark count rate (DCR) after an irradiation with about 108 1-MeV equivalent neutrons/cm2 agrees with observations by others for analog SiPMs, indicating that the radiation damage occurs in the single photon avalanche diodes and not in the electronics integrated on the sensor chip. It was found that in the in situ location, the DCR becomes too large for successful operation after the equivalent of a few weeks of use in a proton therapy treatment room (about 5 × 1013 protons). For PET detectors in an in-room setup, detector performance was unchanged even after an irradiation equivalent to three years of use in a treatment room (3 × 1015 protons).

Characteristics of High Latitude Ionosphere Scintillations

NASA Astrophysics Data System (ADS)

Morton, Y.

2012-12-01

As we enter a new solar maximum period, global navigation satellite systems (GNSS) receivers, especially the ones operating in high latitude and equatorial regions, are facing an increasing threat from ionosphere scintillations. The increased solar activities, however, also offer a great opportunity to collect scintillation data to characterize scintillation signal parameters and ionosphere irregularities. While there are numerous GPS receivers deployed around the globe to monitor ionosphere scintillations, most of them are commercial receivers whose signal processing mechanisms are not designed to operate under ionosphere scintillation. As a result, they may distort scintillation signal parameters or lose lock of satellite signals under strong scintillations. Since 2008, we have established and continuously improved a unique GNSS receiver array at HAARP, Alaska. The array contains high ends commercial receivers and custom RF front ends which can be automatically triggered to collect high quality GPS and GLONASS satellite signals during controlled heating experiments and natural scintillation events. Custom designed receiver signal tracking algorithms aim to preserve true scintillation signatures are used to process the raw RF samples. Signal strength, carrier phase, and relative TEC measurements generated by the receiver array since its inception have been analyzed to characterize high latitude scintillation phenomena. Daily, seasonal, and solar events dependency of scintillation occurrence, spectral contents of scintillation activities, and plasma drifts derived from these measurements will be presented. These interesting results demonstrate the feasibility and effectiveness of our experimental data collection system in providing insightful details of ionosphere responses to active perturbations and natural disturbances.

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

Biassoni, M.; Brofferio, C.; Bucci, C.

Due to their excellent energy resolution values and the vast choice of possible materials, bolometric detectors are currently widely used in the physics of rare events. A limiting aspect for bolometers rises from their inability to discriminate among radiation types or surface from bulk events. It has been demonstrated that the main limitation to sensitivity for purely bolometric detectors is represented by surface alpha contaminations, causing a continuous background that cannot be discriminated. A new scintillation based technique for the rejection of surface alpha background in non- scintillating bolometric experiments is proposed in this work. The idea is to combinemore » a scintillating and a high sensitivity photon detector with a non- scintillating absorber. Finally, we present results showing the possibility to reject events due to alpha decay at or nearby the surface of the crystal.« less

Pulsed neutron detector

DOEpatents

Robertson, deceased, J. Craig; Rowland, Mark S.

1989-03-21

A pulsed neutron detector and system for detecting low intensity fast neutron pulses has a body of beryllium adjacent a body of hydrogenous material the latter of which acts as a beta particle detector, scintillator, and moderator. The fast neutrons (defined as having En>1.5 MeV) react in the beryllium and the hydrogenous material to produce larger numbers of slow neutrons than would be generated in the beryllium itself and which in the beryllium generate hellium-6 which decays and yields beta particles. The beta particles reach the hydrogenous material which scintillates to yield light of intensity related to the number of fast neutrons. A photomultiplier adjacent the hydrogenous material (scintillator) senses the light emission from the scintillator. Utilization means, such as a summing device, sums the pulses from the photo-multiplier for monitoring or other purposes.

Combined FDTD-Monte Carlo analysis and a novel design for ZnO scintillator rods in polycarbonate membrane for X-ray imaging

NASA Astrophysics Data System (ADS)

Mohammadian-Behbahani, Mohammad-Reza; Saramad, Shahyar; Mohammadi, Mohammad

2017-05-01

A combination of Finite Difference Time Domain (FDTD) and Monte Carlo (MC) methods is proposed for simulation and analysis of ZnO microscintillators grown in polycarbonate membrane. A planar 10 keV X-ray source irradiating the detector is simulated by MC method, which provides the amount of absorbed X-ray energy in the assembly. The transport of generated UV scintillation light and its propagation in the detector was studied by the FDTD method. Detector responses to different probable scintillation sites and under different energies of X-ray source from 10 to 25 keV are reported. Finally, the tapered geometry for the scintillators is proposed, which shows enhanced spatial resolution in comparison to cylindrical geometry for imaging applications.

Kilometer-Spaced GNSS Array for Ionospheric Irregularity Monitoring

NASA Astrophysics Data System (ADS)

Su, Yang

This dissertation presents automated, systematic data collection, processing, and analysis methods for studying the spatial-temporal properties of Global Navigation Satellite Systems (GNSS) scintillations produced by ionospheric irregularities at high latitudes using a closely spaced multi-receiver array deployed in the northern auroral zone. The main contributions include 1) automated scintillation monitoring, 2) estimation of drift and anisotropy of the irregularities, 3) error analysis of the drift estimates, and 4) multi-instrument study of the ionosphere. A radio wave propagating through the ionosphere, consisting of ionized plasma, may suffer from rapid signal amplitude and/or phase fluctuations known as scintillation. Caused by non-uniform structures in the ionosphere, intense scintillation can lead to GNSS navigation and high-frequency (HF) communication failures. With specialized GNSS receivers, scintillation can be studied to better understand the structure and dynamics of the ionospheric irregularities, which can be parameterized by altitude, drift motion, anisotropy of the shape, horizontal spatial extent and their time evolution. To study the structuring and motion of ionospheric irregularities at the sub-kilometer scale sizes that produce L-band scintillations, a closely-spaced GNSS array has been established in the auroral zone at Poker Flat Research Range, Alaska to investigate high latitude scintillation and irregularities. Routinely collecting low-rate scintillation statistics, the array database also provides 100 Hz power and phase data for each channel at L1/L2C frequency. In this work, a survey of seasonal and hourly dependence of L1 scintillation events over the course of a year is discussed. To efficiently and systematically study scintillation events, an automated low-rate scintillation detection routine is established and performed for each day by screening the phase scintillation index. The spaced-receiver technique is applied to cross-correlated phase and power measurements from GNSS receivers. Results of horizontal drift velocities and anisotropy ellipses derived from the parameters are shown for several detected events. Results show the possibility of routinely quantifying ionospheric irregularities by drifts and anisotropy. Error analysis on estimated properties is performed to further evaluate the estimation quality. Uncertainties are quantified by ensemble simulation of noise on the phase signals carried through to the observations of the spaced-receiver linear system. These covariances are then propagated through to uncertainties on drifts. A case study of a single scintillating satellite observed by the array is used to demonstrate the uncertainty estimation process. The distributed array is used in coordination with other measuring techniques such as incoherent scatter radar and optical all-sky imagers. These scintillations are correlated with auroral activity, based on all-sky camera images. Measurements and uncertainty estimates made over a 30-minute period are made and compared to a collocated incoherent scatter radar, and show good agreement in horizontal drift speed and direction during periods of scintillation for cases when the characteristic velocity is less than the drift velocity. The methods demonstrated are extensible to other zones and other GNSS arrays of varying size, number, ground distribution, and transmitter frequency.

TH-CD-207B-06: Swank Factor of Segmented Scintillators in Multi-Slice CT Detectors: Pulse Height Spectra and Light Escape

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

Howansky, A; Peng, B; Lubinsky, A

Purpose: Pulse height spectra (PHS) have been used to determine the Swank factor of a scintillator by measuring fluctuations in its light output per x-ray interaction. The Swank factor and x-ray quantum efficiency of a scintillator define the upper limit to its imaging performance, i.e. DQE(0). The Swank factor below the K-edge is dominated by optical properties, i.e. variations in light escape efficiency from different depths of interaction, denoted e(z). These variations can be optimized to improve tradeoffs in x-ray absorption, light yield, and spatial resolution. This work develops a quantitative model for interpreting measured PHS, and estimating e(z) onmore » an absolute scale. The method is used to investigate segmented ceramic GOS scintillators used in multi-slice CT detectors. Methods: PHS of a ceramic GOS plate (1 mm thickness) and segmented GOS array (1.4 mm thick) were measured at 46 keV. Signal and noise propagation through x-ray conversion gain, light escape, detection by a photomultiplier tube and dynode amplification were modeled using a cascade of stochastic gain stages. PHS were calculated with these expressions and compared to measurements. Light escape parameters were varied until modeled PHS agreed with measurements. The resulting estimates of e(z) were used to calculate PHS without measurement noise to determine the inherent Swank factor. Results: The variation in e(z) was 67.2–89.7% in the plate and 40.2–70.8% in the segmented sample, corresponding to conversion gains of 28.6–38.1 keV{sup −1} and 17.1–30.1 keV{sup −1}, respectively. The inherent Swank factors of the plate and segmented sample were 0.99 and 0.95, respectively. Conclusion: The high light escape efficiency in the ceramic GOS samples yields high Swank factors and DQE(0) in CT applications. The PHS model allows the intrinsic optical properties of scintillators to be deduced from PHS measurements, thus it provides new insights for evaluating the imaging performance of segmented ceramic GOS scintillators.« less

A tetrahedron beam computed tomography benchtop system with a multiple pixel field emission x-ray tube.

PubMed

Xu, Xiaochao; Kim, Joshua; Laganis, Philip; Schulze, Derek; Liang, Yongguang; Zhang, Tiezhi

2011-10-01

To demonstrate the feasibility of Tetrahedron Beam Computed Tomography (TBCT) using a carbon nanotube (CNT) multiple pixel field emission x-ray (MPFEX) tube. A multiple pixel x-ray source facilitates the creation of novel x-ray imaging modalities. In a previous publication, the authors proposed a Tetrahedron Beam Computed Tomography (TBCT) imaging system which comprises a linear source array and a linear detector array that are orthogonal to each other. TBCT is expected to reduce scatter compared with Cone Beam Computed Tomography (CBCT) and to have better detector performance. Therefore, it may produce improved image quality for image guided radiotherapy. In this study, a TBCT benchtop system has been developed with an MPFEX tube. The tube has 75 CNT cold cathodes, which generate 75 x-ray focal spots on an elongated anode, and has 4 mm pixel spacing. An in-house-developed, 5-row CT detector array using silicon photodiodes and CdWO(4) scintillators was employed in the system. Hardware and software were developed for tube control and detector data acquisition. The raw data were preprocessed for beam hardening and detector response linearity and were reconstructed with an FDK-based image reconstruction algorithm. The focal spots were measured at about 1 × 2 mm(2) using a star phantom. Each cathode generates around 3 mA cathode current with 2190 V gate voltage. The benchtop system is able to perform TBCT scans with a prolonged scanning time. Images of a commercial CT phantom were successfully acquired. A prototype system was developed, and preliminary phantom images were successfully acquired. MPFEX is a promising x-ray source for TBCT. Further improvement of tube output is needed in order for it to be used in clinical TBCT systems.

Prompt directional detection of galactic supernova by combining large liquid scintillator neutrino detectors

NASA Astrophysics Data System (ADS)

Fischer, V.; Chirac, T.; Lasserre, T.; Volpe, C.; Cribier, M.; Durero, M.; Gaffiot, J.; Houdy, T.; Letourneau, A.; Mention, G.; Pequignot, M.; Sibille, V.; Vivier, M.

2015-08-01

Core-collapse supernovae produce an intense burst of electron antineutrinos in the few-tens-of-MeV range. Several Large Liquid Scintillator-based Detectors (LLSD) are currently operated worldwide, being very effective for low energy antineutrino detection through the Inverse Beta Decay (IBD) process. In this article, we develop a procedure for the prompt extraction of the supernova location by revisiting the details of IBD kinematics over the broad energy range of supernova neutrinos. Combining all current scintillator-based detector, we show that one can locate a canonical supernova at 10 kpc with an accuracy of 45 degrees (68% C.L.). After the addition of the next generation of scintillator-based detectors, the accuracy could reach 12 degrees (68% C.L.), therefore reaching the performances of the large water Čerenkov neutrino detectors. We also discuss a possible improvement of the SuperNova Early Warning System (SNEWS) inter-experiment network with the implementation of a directionality information in each experiment. Finally, we discuss the possibility to constrain the neutrino energy spectrum as well as the mass of the newly born neutron star with the LLSD data.

Baby MIND: A Magnetized Segmented Neutrino Detector for the WAGASCI Experiment

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

Antonova, M.; et al.

T2K (Tokai-to-Kamioka) is a long-baseline neutrino experiment in Japan designed to study various parameters of neutrino oscillations. A near detector complex (ND280) is located 280 m downstream of the production target and measures neutrino beam parameters before any oscillations occur. ND280's measurements are used to predict the number and spectra of neutrinos in the Super-Kamiokande detector at the distance of 295 km. The difference in the target material between the far (water) and near (scintillator, hydrocarbon) detectors leads to the main non-cancelling systematic uncertainty for the oscillation analysis. In order to reduce this uncertainty a new WAter-Grid-And-SCintillator detector (WAGASCI) hasmore » been developed. A magnetized iron neutrino detector (Baby MIND) will be used to measure momentum and charge identification of the outgoing muons from charged current interactions. The Baby MIND modules are composed of magnetized iron plates and long plastic scintillator bars read out at the both ends with wavelength shifting fibers and silicon photomultipliers. The front-end electronics board has been developed to perform the readout and digitization of the signals from the scintillator bars. Detector elements were tested with cosmic rays and in the PS beam at CERN. The obtained results are presented in this paper.« less

Baby MIND: a magnetized segmented neutrino detector for the WAGASCI experiment

NASA Astrophysics Data System (ADS)

Antonova, M.; Asfandiyarov, R.; Bayes, R.; Benoit, P.; Blondel, A.; Bogomilov, M.; Bross, A.; Cadoux, F.; Cervera, A.; Chikuma, N.; Dudarev, A.; Ekelöf, T.; Favre, Y.; Fedotov, S.; Hallsjö, S.-P.; Izmaylov, A.; Karadzhov, Y.; Khabibullin, M.; Khotyantsev, A.; Kleymenova, A.; Koga, T.; Kostin, A.; Kudenko, Y.; Likhacheva, V.; Martinez, B.; Matev, R.; Medvedeva, M.; Mefodiev, A.; Minamino, A.; Mineev, O.; Nessi, M.; Nicola, L.; Noah, E.; Ovsiannikova, T.; Pais Da Silva, H.; Parsa, S.; Rayner, M.; Rolando, G.; Shaykhiev, A.; Simion, P.; Soler, F. J. P.; Suvorov, S.; Tsenov, R.; Ten Kate, H.; Vankova-Kirilova, G.; Yershov, N.

2017-07-01

T2K (Tokai-to-Kamioka) is a long-baseline neutrino experiment in Japan designed to study various parameters of neutrino oscillations. A near detector complex (ND280) is located 280 m downstream of the production target and measures neutrino beam parameters before any oscillations occur. ND280's measurements are used to predict the number and spectra of neutrinos in the Super-Kamiokande detector at the distance of 295 km. The difference in the target material between the far (water) and near (scintillator, hydrocarbon) detectors leads to the main non-cancelling systematic uncertainty for the oscillation analysis. In order to reduce this uncertainty a new WAter-Grid-And-SCintillator detector (WAGASCI) has been developed. A magnetized iron neutrino detector (Baby MIND) will be used to measure momentum and charge identification of the outgoing muons from charged current interactions. The Baby MIND modules are composed of magnetized iron plates and long plastic scintillator bars read out at the both ends with wavelength shifting fibers and silicon photomultipliers. The front-end electronics board has been developed to perform the readout and digitization of the signals from the scintillator bars. Detector elements were tested with cosmic rays and in the PS beam at CERN. The obtained results are presented in this paper.

Characterization of the exradin W1 plastic scintillation detector for small field applications in proton therapy.

PubMed

Hoehr, C; Lindsay, C; Beaudry, J; Penner, C; Strgar, V; Lee, R; Duzenli, C

2018-05-04

Accurate dosimetry in small field proton therapy is challenging, particularly for applications such as ocular therapy, and suitable detectors for this purpose are sought. The Exradin W1 plastic scintillating fibre detector is known to out-perform most other detectors for determining relative dose factors for small megavoltage photon beams used in radiotherapy but its potential in small proton beams has been relatively unexplored in the literature. The 1 mm diameter cylindrical geometry and near water equivalence of the W1 makes it an attractive alternative to other detectors. This study examines the dosimetric performance of the W1 in a 74 MeV proton therapy beam with particular focus on detector response characteristics relevant to relative dose measurement in small fields suitable for ocular therapy. Quenching of the scintillation signal is characterized and demonstrated not to impede relative dose measurements at a fixed depth. The background cable-only (Čerenkov and radio-fluorescence) signal is 4 orders of magnitude less than the scintillation signal, greatly simplifying relative dose measurements. Comparison with other detectors and Monte Carlo simulations indicate that the W1 is useful for measuring relative dose factors for field sizes down to 5 mm diameter and shallow spread out Bragg peaks down to 6 mm in depth.

Characterization of the exradin W1 plastic scintillation detector for small field applications in proton therapy

NASA Astrophysics Data System (ADS)

Hoehr, C.; Lindsay, C.; Beaudry, J.; Penner, C.; Strgar, V.; Lee, R.; Duzenli, C.

2018-05-01

Accurate dosimetry in small field proton therapy is challenging, particularly for applications such as ocular therapy, and suitable detectors for this purpose are sought. The Exradin W1 plastic scintillating fibre detector is known to out-perform most other detectors for determining relative dose factors for small megavoltage photon beams used in radiotherapy but its potential in small proton beams has been relatively unexplored in the literature. The 1 mm diameter cylindrical geometry and near water equivalence of the W1 makes it an attractive alternative to other detectors. This study examines the dosimetric performance of the W1 in a 74 MeV proton therapy beam with particular focus on detector response characteristics relevant to relative dose measurement in small fields suitable for ocular therapy. Quenching of the scintillation signal is characterized and demonstrated not to impede relative dose measurements at a fixed depth. The background cable-only (Čerenkov and radio-fluorescence) signal is 4 orders of magnitude less than the scintillation signal, greatly simplifying relative dose measurements. Comparison with other detectors and Monte Carlo simulations indicate that the W1 is useful for measuring relative dose factors for field sizes down to 5 mm diameter and shallow spread out Bragg peaks down to 6 mm in depth.

Commissioning the SNO+ Detector

NASA Astrophysics Data System (ADS)

Caden, E.; Coulter, I.; SNO+ Collaboration

2017-09-01

SNO+ is a multipurpose liquid scintillator neutrino experiment based at SNOLAB in Sudbury, Ontario, Canada. The experiment’s main physics goal is a search for neutrinoless double beta decay in Tellurium-130, but SNO+ will also study low energy solar neutrinos, geo- and reactor-antineutrinos, among other topics. We are reusing much of the hardware from the original SNO experiment, but significant work has taken place to transform the heavy water detector into a liquid scintillator detector. We present upgrades and improvements to the read-out electronics and trigger system to handle the higher data rates expected by a scintillator experiment. We show the successful installation and testing of a hold-down rope net for the acrylic vessel to counter-act the buoyancy of organic liquid scintillator. We also describe the new scintillator process plant and cover gas systems that have been constructed to achieve the purification necessary to meet our physics goals. We are currently commissioning the experiment with ultra-pure water in preparation for filling with scintillator in early 2017 and present the current status of this work.

A Hand-Held, Intra-Operative Positron Imaging Probe for Surgical Applications

NASA Astrophysics Data System (ADS)

Sabet, Hamid; Stack, Brendan C.; Nagarkar, Vivek V.

2015-10-01

We have developed a prototype intra-operative β+ imaging probe to help tumor removal and malignant tissue resection. The probe can be used during surgery to provide clear delineation of malignant tissues. Our probe consists of a hybrid scintillator coupled to a silicon photomultiplier (SiPM) array with associated front-end electronics encapsulated in an ergonomic aluminum housing. Pulse shape discrimination electronics has been implemented and integrated into the downstream data acquisition system. The field of view of the probe is 10 ×10 mm2 realized by a 0.4 mm thick CsI:Tl scintillator coupled to a 1 mm thick LYSO. While CsI:Tl layer acts as β+ sensitive detector, LYSO detects gamma radiation where the gamma response can be subtracted from the total signal to improve SNR and contrast. The thickness of the LYSO scintillator is optimized such that it acts as light diffuser to spread the scintillation light generated in CsI:Tl over multiple SiPM pixels for accurate estimation of the β+ interaction location. The probe shows FWHM spatial resolution in the presence of large background radiation. The probe was used to study rabbits with tongue tumors. The experimental results show that the probe can successfully locate the tongue tumors in its active imaging area.

Design of an ultrathin cold neutron detector

NASA Astrophysics Data System (ADS)

Osovizky, A.; Pritchard, K.; Yehuda-Zada, Y.; Ziegler, J.; Binkley, E.; Tsai, P.; Thompson, A.; Hadad, N.; Jackson, M.; Hurlbut, C.; Baltic, G. M.; Majkrzak, C. F.; Maliszewskyj, N. C.

2018-06-01

We describe the design and performance of an ultrathin (<2 mm) cold neutron detector consisting of 6LiF:ZnS(Ag) scintillator in which wavelength shifting fibers have been embedded to conduct scintillation photons out of the medium to a silicon photomultiplier photosensor. The counter has a neutron sensitive volume of 12 mm wide × 30 mm high × 1.4 mm deep. Twenty-four 0.5 mm diameter wavelength shifting fibers conduct the scintillation light out of the plane of the detector and are concentrated onto a 3 mm × 3 mm silicon photomultiplier. The detector is demonstrated to possess a neutron detection efficiency of 93% for 3.27 meV neutrons with a gamma ray rejection ratio on the order of 10-7.

Measurement of nuclear resonant scattering on 61Ni with fast scintillation detector using proportional-mode silicon avalanche photodiode

NASA Astrophysics Data System (ADS)

Inoue, Keisuke; Kobayashi, Yasuhiro; Yoda, Yoshitaka; Koshimizu, Masanori; Nishikido, Fumihiko; Haruki, Rie; Kishimoto, Shunji

2018-02-01

We developed a new scintillation timing detector using a proportional-mode silicon avalanche photodiode (Si-APD) for synchrotron radiation nuclear resonant scattering. We report on the nuclear forward scattering measurement on 61Ni with a prototype detector using a lead-loaded plastic scintillator (EJ-256, 3 mm in diameter and 2 mm in thickness), mounted on a proportional-mode Si-APD. Using synchrotron X-rays of 67.41 keV, we successfully measured the time spectra of nuclear forward scattering on 61Ni enriched metal foil and 61Ni86V14 alloy. The prototype detector confirmed the expected dynamical beat structure with a time resolution of 0.53 ns (FWHM).

Nuclear Science Symposium, 21st, Scintillation and Semiconductor Counter Symposium, 14th, and Nuclear Power Systems Symposium, 6th, Washington, D.C., December 11-13, 1974, Proceedings

NASA Technical Reports Server (NTRS)

1975-01-01

Papers are presented dealing with latest advances in the design of scintillation counters, semiconductor radiation detectors, gas and position sensitive radiation detectors, and the application of these detectors in biomedicine, satellite instrumentation, and environmental and reactor instrumentation. Some of the topics covered include entopistic scintillators, neutron spectrometry by diamond detector for nuclear radiation, the spherical drift chamber for X-ray imaging applications, CdTe detectors in radioimmunoassay analysis, CAMAC and NIM systems in the space program, a closed loop threshold calibrator for pulse height discriminators, an oriented graphite X-ray diffraction telescope, design of a continuous digital-output environmental radon monitor, and the optimization of nanosecond fission ion chambers for reactor physics. Individual items are announced in this issue.

System and method for assaying a radionuclide

DOEpatents

Cadieux, James R; King, III, George S; Fugate, Glenn A

2014-12-23

A system for assaying a radionuclide includes a liquid scintillation detector, an analyzer connected to the liquid scintillation detector, and a delay circuit connected to the analyzer. A gamma detector and a multi-channel analyzer are connected to the delay circuit and the gamma detector. The multi-channel analyzer produces a signal reflective of the radionuclide in the sample. A method for assaying a radionuclide includes selecting a sample, detecting alpha or beta emissions from the sample with a liquid scintillation detector, producing a first signal reflective of the alpha or beta emissions, and delaying the first signal a predetermined time. The method further includes detecting gamma emissions from the sample, producing a second signal reflective of the gamma emissions, and combining the delayed first signal with the second signal to produce a third signal reflective of the radionuclide.

Status and prospects of the SNO+ experiment

NASA Astrophysics Data System (ADS)

Maneira, J.

2016-05-01

The SNO+ experiment is located at the SNOLAB underground laboratory and will employ 780 tons of liquid scintillator loaded, in its initial phase, with 800 kg of 130Te (0.3% by mass) for a low-background and high-isotope-mass search for neutrino-less double beta decay. SNO+ reuses the acrylic vessel and PMT array of the SNO detector, but several experimental upgrades and adaptations were necessary to allow for the use of liquid scintillator. The SNO+ technique allows a staged approach, and extensive R&D is ongoing to increase the loadings and improve the purification of Tellurium. The very good conditions of background and low energy threshold allow SNO+ to also have other physics topics in its program, including geo- and reactor neutrinos, Supernova and solar neutrinos. This talk will describe the main advantages and challenges of the SNO+ approach for the double-beta decay program, the current status of the experiment and its sensitivity prospects.

On-line remote monitoring of radioactive waste repositories

NASA Astrophysics Data System (ADS)

Calì, Claudio; Cosentino, Luigi; Litrico, Pietro; Pappalardo, Alfio; Scirè, Carlotta; Scirè, Sergio; Vecchio, Gianfranco; Finocchiaro, Paolo; Alfieri, Severino; Mariani, Annamaria

2014-12-01

A low-cost array of modular sensors for online monitoring of radioactive waste was developed at INFN-LNS. We implemented a new kind of gamma counter, based on Silicon PhotoMultipliers and scintillating fibers, that behaves like a cheap scintillating Geiger-Muller counter. It can be placed in shape of a fine grid around each single waste drum in a repository. Front-end electronics and an FPGA-based counting system were developed to handle the field data, also implementing data transmission, a graphical user interface and a data storage system. A test of four sensors in a real radwaste storage site was performed with promising results. Following the tests an agreement was signed between INFN and Sogin for the joint development and installation of a prototype DMNR (Detector Mesh for Nuclear Repository) system inside the Garigliano radwaste repository in Sessa Aurunca (CE, Italy). Such a development is currently under way, with the installation foreseen within 2014.

Performance characterization of high quantum efficiency metal package photomultiplier tubes for time-of-flight and high-resolution PET applications.

PubMed

Ko, Guen Bae; Lee, Jae Sung

2015-01-01

Metal package photomultiplier tubes (PMTs) with a metal channel dynode structure have several advanced features for devising such time-of-flight (TOF) and high spatial resolution positron emission tomography (PET) detectors, thanks to their high packing density, large effective area ratio, fast time response, and position encoding capability. Here, we report on an investigation of new metal package PMTs with high quantum efficiency (QE) for high-resolution PET and TOF PET detector modules. The latest metal package PMT, the Hamamatsu R11265 series, is served with two kinds of photocathodes that have higher quantum efficiency than normal bialkali (typical QE ≈ 25%), super bialkali (SBA; QE ≈ 35%), and ultra bialkali (UBA; QE ≈ 43%). In this study, the authors evaluated the performance of the new PMTs with SBA and UBA photocathodes as a PET detector by coupling various crystal arrays. They also investigated the performance improvements of high QE, focusing in particular on a block detector coupled with a lutetium-based scintillator. A single 4 × 4 × 10 mm(3) LYSO, a 7 × 7 array of 3 × 3 × 20 mm(3) LGSO, a 9 × 9 array of 1.2 × 1.2 × 10 mm(3) LYSO, and a 6 × 6 array of 1.5 × 1.5 × 7 mm(3) LuYAP were used for evaluation. All coincidence data were acquired with a DRS4 based fast digitizer. This new PMT shows promising crystal positioning accuracy, energy and time discrimination performance for TOF, and high-resolution PET applications. The authors also found that a metal channel PMT with SBA was enough for both TOF and high-resolution application, although UBA gave a minor improvement to time resolution. However, significant performance improvement was observed in relative low light output crystals (LuYAP) coupled with UBA. The results of this study will be of value as a useful reference to select PMTs for high-performance PET detectors.

ZnO:Zn/6LiF scintillator-A low afterglow alternative to ZnS:Ag/6LiF for thermal neutron detection

NASA Astrophysics Data System (ADS)

Sykora, G. Jeff; Schooneveld, Erik M.; Rhodes, Nigel J.

2018-03-01

Current ZnS:Ag/6LiF based scintillation detectors are often count rate limited by the long lifetime afterglow in the scintillator. Despite this drawback, new instruments at neutron scattering facilities, like ISIS in the UK, would still like to use ZnS:Ag/6LiF detectors due to their low gamma sensitivity, high light output, simplicity of detector design and relatively inexpensive production. One particular advantage of ZnS:Ag/6LiF detectors is their ability to provide strong pulse shape discrimination between neutrons and gammas. Despite the advantages of these detectors, it is becoming clear that new and upgraded instruments will be limited by the count rate capability of ZnS:Ag/6LiF, so an alternative scintillator technology with equivalent simplicity is being sought. ZnO:Zn/6LiF is investigated here as a low afterglow alternative to ZnS:Ag/6LiF. Basic scintillation properties of ZnO:Zn are studied and are discussed. Pulse shape discrimination between neutrons and gammas is explored and taken advantage of through simple single photon counting methods. A further step toward a realistic detector for neutron scattering is also taken by fiber coupling the ZnO:Zn/6LiF to a PMT. In an initial study of this fiber coupled configuration, 60Co gamma sensitivity of ∼ 7 × 10-6 is shown and improvements in count rate capability of at least a factor of 6 over ZnS:Ag/6LiF based neutron detectors are demonstrated.

Gamma ray spectroscopy employing divalent europium-doped alkaline earth halides and digital readout for accurate histogramming

DOEpatents

Cherepy, Nerine Jane; Payne, Stephen Anthony; Drury, Owen B; Sturm, Benjamin W

2014-11-11

A scintillator radiation detector system according to one embodiment includes a scintillator; and a processing device for processing pulse traces corresponding to light pulses from the scintillator, wherein pulse digitization is used to improve energy resolution of the system. A scintillator radiation detector system according to another embodiment includes a processing device for fitting digitized scintillation waveforms to an algorithm based on identifying rise and decay times and performing a direct integration of fit parameters. A method according to yet another embodiment includes processing pulse traces corresponding to light pulses from a scintillator, wherein pulse digitization is used to improve energy resolution of the system. A method in a further embodiment includes fitting digitized scintillation waveforms to an algorithm based on identifying rise and decay times; and performing a direct integration of fit parameters. Additional systems and methods are also presented.

Si-strip photon counting detectors for contrast-enhanced spectral mammography

NASA Astrophysics Data System (ADS)

Chen, Buxin; Reiser, Ingrid; Wessel, Jan C.; Malakhov, Nail; Wawrzyniak, Gregor; Hartsough, Neal E.; Gandhi, Thulasi; Chen, Chin-Tu; Iwanczyk, Jan S.; Barber, William C.

2015-08-01

We report on the development of silicon strip detectors for energy-resolved clinical mammography. Typically, X-ray integrating detectors based on scintillating cesium iodide CsI(Tl) or amorphous selenium (a-Se) are used in most commercial systems. Recently, mammography instrumentation has been introduced based on photon counting Si strip detectors. The required performance for mammography in terms of the output count rate, spatial resolution, and dynamic range must be obtained with sufficient field of view for the application, thus requiring the tiling of pixel arrays and particular scanning techniques. Room temperature Si strip detector, operating as direct conversion x-ray sensors, can provide the required speed when connected to application specific integrated circuits (ASICs) operating at fast peaking times with multiple fixed thresholds per pixel, provided that the sensors are designed for rapid signal formation across the X-ray energy ranges of the application. We present our methods and results from the optimization of Si-strip detectors for contrast enhanced spectral mammography. We describe the method being developed for quantifying iodine contrast using the energy-resolved detector with fixed thresholds. We demonstrate the feasibility of the method by scanning an iodine phantom with clinically relevant contrast levels.

Scintillator materials containing lanthanum fluorides

DOEpatents

Moses, William W.

1991-01-01

An improved radiation detector containing a crystalline mixture of LaF.sub.3 and CeF.sub.3 as the scintillator element is disclosed. Scintillators made with from 25% to 99.5% LaF.sub.3 and the remainder CeF.sub.3 have been found to provide a balance of good stopping power, high light yield and short decay constant that is equal to or superior to other known scintillator materials, and which may be processed from natural starting materials containing both rare earth elements. The radiation detectors disclosed are favorably suited for use in general purpose detection and in positron emission tomography.

Scintillator materials containing lanthanum fluorides

DOEpatents

Moses, W.W.

1991-05-14

An improved radiation detector containing a crystalline mixture of LaF[sub 3] and CeF[sub 3] as the scintillator element is disclosed. Scintillators made with from 25% to 99.5% LaF[sub 3] and the remainder CeF[sub 3] have been found to provide a balance of good stopping power, high light yield and short decay constant that is equal to or superior to other known scintillator materials, and which may be processed from natural starting materials containing both rare earth elements. The radiation detectors disclosed are favorably suited for use in general purpose detection and in positron emission tomography. 2 figures.

Neutron coincidence detectors employing heterogeneous materials

DOEpatents

Czirr, J. Bartley; Jensen, Gary L.

1993-07-27

A neutron detector relies upon optical separation of different scintillators to measure the total energy and/or number of neutrons from a neutron source. In pulse mode embodiments of the invention, neutrons are detected in a first detector which surrounds the neutron source and in a second detector surrounding the first detector. An electronic circuit insures that only events are measured which correspond to neutrons first detected in the first detector followed by subsequent detection in the second detector. In spectrometer embodiments of the invention, neutrons are thermalized in the second detector which is formed by a scintillator-moderator and neutron energy is measured from the summed signals from the first and second detectors.

Device for Detection of Explosives, Nuclear and Other Hazardous Materials in Luggage and Cargo Containers

NASA Astrophysics Data System (ADS)

Kuznetsov, Andrey; Evsenin, Alexey; Gorshkov, Igor; Osetrov, Oleg; Vakhtin, Dmitry

2009-12-01

Device for detection of explosives, radioactive and heavily shielded nuclear materials in luggage and cargo containers based on Nanosecond Neutron Analysis/Associated Particles Technique (NNA/APT) is under construction. Detection module consists of a small neutron generator with built-in position-sensitive detector of associated alpha-particles, and several scintillator-based gamma-ray detectors. Explosives and other hazardous chemicals are detected by analyzing secondary high-energy gamma-rays from reactions of fast neutrons with materials inside a container. The same gamma-ray detectors are used to detect unshielded radioactive and nuclear materials. An array of several neutron detectors is used to detect fast neutrons from induced fission of nuclear materials. Coincidence and timing analysis allows one to discriminate between fission neutrons and scattered probing neutrons. Mathematical modeling by MCNP5 and MCNP-PoliMi codes was used to estimate the sensitivity of the device and its optimal configuration. Comparison of the features of three gamma detector types—based on BGO, NaI and LaBr3 crystals is presented.

Low noise scintillation detectors with a P-47 thin layer screen for electrons of several keV

NASA Astrophysics Data System (ADS)

Kajcsos, Zs.; Meisel, W.; Griesbach, P.; Gütlich, P.; Sauer, Ch.; Kurz, R.; Hildebrand, K.; Albrecht, R.; Ligtenberg, M. A. C.

1994-09-01

The applicability of a low-noise scintillation detector (ScD) for the registration of electrons of several keV energy has been studied employing photomultipliers (PM) of different types and sizes. With the application of a sedimented P-47 scintillation screen, the values of the low-energy sensitivity limit and those of the light conversion coefficient were determined as about 2.7-4.7 keV and 2.8-6.6 photoelectrons/keV, respectively, for the set of PM's (Philips-Valvo XP 2020, Philips-Valvo XP 2052, Philips-Valvo XP 2972, EMI 9124a) studied. It is concluded that such scintillation detectors might be used advantageously as electron counters in the range of E > 5 keV. Applications below this kinetic energy value are also feasible when applying a floating acceleration of several kV to the ScD — a voltage much lower than the values required for Everhart-Thornley detectors.

Development of a flexible γ-ray detector using a liquid scintillation light guide (LSLG).

PubMed

Nomura, Kiyoshi; Yunoki, Akira; Hara, Masayuki; Morito, Yuko; Fujishima, Akira

2018-04-10

A flexible γ detector using a liquid scintillation light guide (LSLG) was developed. The analyzed pulse height (PHA) spectrum depended on the diameter, length and scintillator concentration of the LSLG, and the distance of a γ ray irradiation point from the head of photomultiplier tube (PMT). From the analysis of PHA spectrum, it was found that the count ratio of two divided channel regions linearly decreases as the distance from the PMT head increases. It was further found that the radiation dose rate can be estimated by setting the flexible LSLG tube to a circular shape since the count rate is proportional to the dose rate measured by a conventional NaI (Tl) scintillation detector. Therefore, a flexible and long LSLG detector using a single PMT is useful for determination of the dose rate and has a potential to detect local contaminations in a certain narrow space. Copyright © 2018. Published by Elsevier Ltd.

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

Rottmann, J; Myronakis, M; Hu, Y

Purpose: Beams-eye-view imaging applications such as real-time soft-tissue motion estimation and MV-CBCT are hindered by the inherently low image contrast of electronic portal imaging devices (EPID) currently in clinical use. We investigate a cost effective scintillating glass that provides substantially increased detective quantum efficiency (DQE) and contrast to noise ratio (CNR). Methods: A pixelated scintillator prototype was built from LKH-5 glass. The array is 12mm thick; 42.4×42.4cm2 wide and features 1.51mm pixel pitch with 20µm separation (glue+septa). The LKH-5 array was mounted on the active matrix flat panel imager (AMPFI) of an AS-1200 (Varian) with the GdO2S2:Tb removed. A secondmore » AS-1200 was utilized as reference detector. The prototype EPID was characterized in terms of CNR, modulation transfer function (MTF) and DQE. Additionally, the visibility of various fiducial markers typically used in the clinic as well as a realistic 3D-printed lung tumor model was assessed. All items were placed in a 12cm thick solid water phantom. CNR is estimated using a Las Vegas contrast phantom, presampled MTF is estimated using a slanted slit technique and the DQE is calculated from measured normalized noise power spectra (NPS) and the MTF. Results: DQE(0) for the LKH-5 prototype increased by a factor of 8× to about 10%, compared to the AS-1200 equipped with its standard GdO2S2:Tb scintillator. CNR increased by a factor of 5.3×. Due to the pixel size the MTF50 decreased by about 55% to 0.23lp/mm. The visibility of all fiducial markers as well as the tumor model were however markedly improved in comparison to an acquisition with the same parameters using the GdO2S2:Tb scintillator. Conclusion: LKH-5 scintillating glasses allow the cost effective construction of thick pixelated scintillators for portal imaging which can yield a substantial increase in DQE and CNR. Soft tissue and fiducial marker visibility was found to be markedly improved. The project was supported in part by NIH grant R01CA188446-01 and a grant from Varian Medical Systems.« less