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1

Extruded Plastic Scintillation Detectors  

Microsoft Academic Search

As a way to lower the cost of plastic scintillation detectors, commercially available polystyrene pellets have been used in the production of scintillating materials that can be extruded into different profiles. The selection of raw materials is discussed. Two techniques to add wavelength shifting dopants to polystyrene pellets and to extrude plastic scintillating strips are described. Data on light yield

Anna Pla-Dalmau; Alan D. Bross; Kerry L. Mellott

1999-01-01

2

Extruded plastic scintillation detectors  

Microsoft Academic Search

As a way to lower the cost of plastic scintillation detectors, commercially available polystyrene pellets have been used in the production of scintillating materials that can be extruded into different profiles. The selection of the raw materials is discussed. Two techniques to add wavelength shifting dopants to polystyrene pellets and to extrude plastic scintillating strips are described. Data on light

Anna Pla-Dalmau; Alan D. Bross; Kerry L. Mellott

1999-01-01

3

Liquid Scintillator Detectors  

NASA Astrophysics Data System (ADS)

In this paper new developments and applications for the use of future liquid scintillator detectors like the proposed 50kt large LENA project are presented. New aspects of the scientific potential of LENA, including long baseline oscillation measurements, are discussed.

Oberauer, L.

2013-02-01

4

SCINTILLATION EXPOSURE RATE DETECTOR  

DOEpatents

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.

Spears, W.G.

1960-11-01

5

a Subminiature Scintillation Detector for Catheter Operation  

NASA Astrophysics Data System (ADS)

The feasibility of a subminiature scintillation detector to be inserted in a catheter for lesion localization in nuclear medicine SPECT has been studied. Measurements on a simple laboratory setup have been performed and compared with Monte Carlo results. Further simulations, at 30keV and 140keV, concerning a configuration reproducing severe clinical conditions have shown poor lesion detectability. Several factors affecting the response have to be investigated to improve the capability of lesion localization characterizing such detector.

Scafè, R.; Montani, L.; Burgio, N.; Iurlaro, G.; Santagata, A.; Ciavola, C.; Alonge, G.

2006-04-01

6

Scintillation materials for neutron imaging detectors  

Microsoft Academic Search

We have researched scintillation materials for neutron imaging detectors with a photon counting method. The aim of the research was to develop optimal scintillators, which have the well-balanced performances in detection efficiency, counting rate, n\\/? ratio, multi-counting rate, and neutron\\/? ratio for neutron scattering equipments using high-intensity pulsed neutron sources. The following scintillation materials were researched: ZnS-series phosphors with neutron

M. Katagiri; K. Sakasai; M. Matsubayashi; T. Nakamura; Y. Kondo; Y. Chujo; H. Nanto; T. Kojima

2004-01-01

7

Gamma-ray scintillation detector  

Microsoft Academic Search

A plurality of independent scintillators are used to measure radiation dose rate. The opening of a light shielding shutter locating the scintillators and a photomultiplier is adjusted to maintain linear proportional relationship between the counting rate and the dose rate.

H. Tatsuta; S. Kumazawa

1977-01-01

8

Large volume flow-through scintillating detector  

DOEpatents

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.

Gritzo, Russ E. (Los Alamos, NM); Fowler, Malcolm M. (Los Alamos, NM)

1995-01-01

9

A study of the performance of elongated scintillation detectors  

Microsoft Academic Search

The performance of scintillation detectors of varied length and design was investigated in order to work out an optimum variant, of elongated shape, in the development of a total-absorption scintillation spectrometer. The degree of nonuniformity of the detector is isolated and defined as the most important characteristic. Excellent uniformity in light collection was attained in large-area scintillation detectors of elongated

V. G. Abulova; V. M. Mialkovskii; A. D. Nurkhodzhaev; T. S. Iuldashbaev

1976-01-01

10

High resolution scintillation detector with semiconductor readout  

DOEpatents

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.

Levin, Craig S. (Santa Monica, CA); Hoffman, Edward J. (Los Angeles, CA)

2000-01-01

11

Nanocomposite scintillator, detector, and method  

DOEpatents

A compact includes a mixture of a solid binder and at least one nanopowder phosphor chosen from yttrium oxide, yttrium tantalate, barium fluoride, cesium fluoride, bismuth germanate, zinc gallate, calcium magnesium pyrosilicate, calcium molybdate, calcium chlorovanadate, barium titanium pyrophosphate, a metal tungstate, a cerium doped nanophosphor, a bismuth doped nanophosphor, a lead doped nanophosphor, a thallium doped sodium iodide, a doped cesium iodide, a rare earth doped pyrosilicate, or a lanthanide halide. The compact can be used in a radiation detector for detecting ionizing radiation.

Cooke, D. Wayne (Santa Fe, NM); McKigney, Edward A. (Los Alamos, NM); Muenchausen, Ross E. (Los Alamos, NM); Bennett, Bryan L. (Los Alamos, NM)

2009-04-28

12

Dual scintillation detector for determining grade of uranium ore  

Microsoft Academic Search

A dual scintillation radiation detector having two different scintillation detector materials arranged and shaped in order to detect and determine the quantity of the two different radiations such as beta and gamma present within an unknown sample. The detector can be used in apparatus for laboratory use, manual portable probe applications, or in elongated probes for simultaneously reading radiation present

R. Brown; P. A. Proulx

1981-01-01

13

Small inorganic scintillators as neutron detectors  

SciTech Connect

Small organic scintillators that exhibit pulse shape differences (PSD) in response to charged particles have been investigated as possible neutron detectors in the energy range from 1 to 200 MeV. Neutrons in this energy range can induce reactions such as (n,p) and (n,alpha) in these scintillators, and the cross sections for these reactions vary with energy. Pulse-height and PSD distributions were measured as a function of neutron energy for small crystals of NaI(Tl) and CsI(Tl) at the LANSCE-WNR pulsed spallation neutron source. PSD information indicating the relative numbers of protons and alphas produced can give information about the neutron spectrum in fast-neutron radiation fields such as those encountered in space exploration.

Bartle, C.M. [Inst. of Geophysical and Nuclear Sciences, Lower Hutt (New Zealand); Haight, R.C. [Los Alamos National Lab., NM (United States)

1998-12-01

14

New setup for the characterisation of the AGATA detectors  

NASA Astrophysics Data System (ADS)

A crucial step in the process of ?-ray tracking is related to the location of the interaction points of all the ?-rays within the AGATA (Advanced GAmma Tracking Array) segmented detectors. This requires a full understanding of the sensitivity of each highly segmented high-purity germanium (HPGe) detectors via the characterisation of the 2D and 3D position response. In this paper, we describe the experimental scanning setup that we developed at Orsay for the AGATA detectors. A collimated 137Cs source on an automated x-y positioning table was used for the front face scanning of the AGATA symmetric prototype detector. The 3D scanning measurement is performed using coincidence techniques based on ?-ray Compton scattering from the AGATA detector into an ancillary coupled detector. In our setup, TOHR (high resolution tomograph developed for small animal imaging) is used as an ancillary detector. The data is collected using TIGRESS cards for digital signal processing. The data flow, readout and storage is NARVAL as used for the full AGATA project. The analysis of the collected data and the obtained results is shown to illustrate our device performances.

Ha, T. M. H.; Korichi, A.; Le Blanc, F.; Désesquelles, P.; Dosme, N.; Grave, X.; Karkour, N.; Leboutelier, S.; Legay, E.; Linget, D.; Travers, B.; Pariset, P.

2013-01-01

15

A fast scintillation detector for analytical X-ray instruments  

Microsoft Academic Search

A detector was constructed which consisted of a relatively fast plastic scintillator coupled to two photomultipliers operated in coincidence. The coincidence gate reduced noise from random photomultiplier dark current pulses. The scintillator was shaped so that total internal reflection tended to collimate scintillation light, and it was shown that this increase quantum efficiency. Fast counting electronics were built using ECL

J. L. Radtke

1990-01-01

16

A new particle detector based on processed plastic scintillating fiber  

Microsoft Academic Search

Plastic scintillator as a nuclear detection material has been widely used in the field of particle detection as a result of ease of processing into various shapes and low price. In this paper, a new particle detector used in microbeam based on plastic scintillating fiber was introduced. The processing procedure of plastic scintillating fiber and the detection results of particle

Yongjian Xu; Chundong Hu; Jun Li

2010-01-01

17

Light transport contribution to the timing characteristics of scintillation detectors  

Microsoft Academic Search

A Monte Carlo simulation of the light transit time in scintillation detectors is described, with the wavelength dependencies of different interaction processes being taken into account. The simulation results presented give an estimate of the contribution of light transport to the timing resolution of scintillation detectors.

N. Ghal-Eh

2011-01-01

18

Fast neutron detection with pressurized 4He scintillation detectors  

NASA Astrophysics Data System (ADS)

Measurement result and performance parameters are presented for fast neutron detectors exploiting the scintillation of natural helium at high pressure. This detection medium has a very low electron density, minimizing the sensitivity to gamma radiation and thus enabling neutron detection also in high gamma radiation environment. Contrary to proportional counters, scintillation detection enables fast (nanosecond) timing and pulse shape discrimination, a technique that enables a lower neutron detection threshold. In this work, the basic principles of the detector are described, followed by a study of gamma rejection capabilities. Methods to calibrate the detector are discussed. Finally, a brief description of a 4He scintillation based detector system including data acquisition electronics is given.

Chandra, R.; Davatz, G.; Friederich, H.; Gendotti, U.; Murer, D.

2012-03-01

19

Slot scintillation detector modeling for digital radiography  

NASA Astrophysics Data System (ADS)

A scanning slot X-ray digital detector operating at relatively high photon energies, mainly 70kVp for dental radiography, has been designed and modeled. In this energy range, further improvements are required in order to attain optimal image quality for the lowest achievable mean absorbed dose to the patient. This paper concerns the investigation of the physics of imaging using a structured screen composed of a scintillating fiber optic (LKH-6/CCD system) and its performance by Monte Carlo (MC) simulation. The As factor, X-ray cross-talk, quantum noise effect on resultant values of Detective Quantum Efficiency (/DQE) and Modulation Transfer Function (/MTF) are discussed. The results of this paper should serve as a useful guide in the engineering design of future structured screen/CCD based systems.

Alcón, E. P. Q.; Lopes, R. T.

2001-06-01

20

11C Background in Liquid Scintillator Detectors  

SciTech Connect

Cosmogenic 11C produced in muon showers is one of the main backgrounds for the detection of pep and CNO solar neutrinos in underground organic liquid scintillator detectors. Experimental data available for the effective cross section for 11C by muons indicate that 11C is in fact the dominant background for the observation of such neutrinos. 11C decays are expected to total a rate 2.5 (20) times higher than the combined rate of pep and CNO neutrinos in Borexino (KamLAND) in the energy window preferred for the pep measurement, between 0.8 and 1.3 MeV.Background from 11C in organic liquid scintillator detectors can be reduced if a neutron is emitted when the 11C nuclide is created. 11C decays can be tagged on a one-by-one basis using a three-fold coincidence with the parent muon track and the subsequent neutron capture on protons. The efficiency of such background reduction critically relies on the emission of a free neutron associated with 11C production.In order to verify the hypothesis, first suggested by Deutsch, that a neutron is in fact always emitted when 11C is produced, we perform a detailed ab initio calculation of the production of cosmogenic 11C, taking into consideration all relevant production channels. Results of the calculation are compared with the effective cross sections measured by target experiments in muon beams. 'Bilnd' channels without a neutron in the final state account for only about 5% of 11C production modes.An estimation of the effectiveness of the one-by-one tagging of 11C events, in light of such 'blind' channels is performed for KamLAND, Borexino, and a possible scintillator experiment at SNOLab. Both KamLAND and Borexino can significantly improve their pep and CNO solar neutrino signal and could perform a 3% measurement of the pep solar neutrino flux in five years. At SNOLab depths the muon flux is low enough that 11C background would be much smaller than the pep and CNO neutrino signal and hence negligible.

Pocar, Andrea [Physics Department, Stanford University, Stanford, CA 94305 (United States)

2005-09-08

21

Investigation of Plastic Scintillator Detector Configurations for Neutron Studies  

Microsoft Academic Search

Plastic scintillation products are widely used for detecting nuclear radiation. Measurements of the response of plastic scintillator detectors to different radiations are important in the design phase of a detection system and as an initial input in Monte Carlo simulation codes. We performed test measurements of the light response, attenuation length, time and position resolution, and detection efficiency of Bicron

Catalin Matei; D. W. Bardayan; J. C. Blackmon; J. A. Howard; J. A. Cizewski; P. D. O'Malley; S. D. Pain; W. A. Peters; R. K. Grzywacz; K. L. Jones; S. N. Liddick

2007-01-01

22

A scintillating fiber detector for the D0 upgrade  

SciTech Connect

In the Step 1 version of the D0 upgrade, the inner vertex chamber will be replaced by a system of silicon microstrips surrounded by a scintillating fiber detector. Details of the detector design and status of R D and construction programs for the detector are presented. Progress on the upcoming large-scale cosmic ray test at Fermilab is also reported.

Wayne, M. (Notre Dame Univ., IN (United States). Dept. of Physics)

1993-03-01

23

Optimization of a Scintillation Detector with Hemispherical Configuration.  

National Technical Information Service (NTIS)

A hemispherical configuration for scintillation detectors, is introduced so as to minimize the dispersion in light collection by reducing the number of reflexions. Better results in the process of light collection appear explicitly in the gain in the ampl...

A. C. Saules Mendonca

1980-01-01

24

Measurement of the energy resolution of a scintillating fiber detector  

NASA Astrophysics Data System (ADS)

The energy resolution is measured for a plastic scintillating fiber detector coupled to position sensitive photomultiplier tubes. A point source (Mn-54) is placed at a distance in front of an xy plastic scintillating fiber stack which is coupled to two Hamamatsu R2486 position sensitive photomultiplier tubes. At some distance behind this detector another plastic scintillating detector coupled to another position sensitive photomultiplier is placed. Gamma rays interacting in the first detector are scattered, and interact with the second detector. By the knowledge of the source location, the Compton interaction location in the first detector, and the interaction location of the scattered gamma in detector two, the scattering angle of the Compton interaction in detector one can be determined. From this scattering angle and the known primary gamma energy the Compton electron energy can be calculated. The energy resolution of the scintillating fiber stack-photomultiplier unit of detector one for different Compton electron energies is determined by plotting the experimentally measured electron energies obtained from the light output of the photomultiplier tubes of detector one, comparing them with the electron energy calculated above, and expressed in terms of the FWHM.

Hudson, Cheri; Chaney, Roy C.; Fenyves, Ervin J.; Hammack, H.; Antich, Peter P.

1994-09-01

25

Optimizing timing performance of silicon photomultiplier-based scintillation detectors  

NASA Astrophysics Data System (ADS)

Precise timing resolution is crucial for applications requiring photon time-of-flight (ToF) information such as ToF positron emission tomography (PET). Silicon photomultipliers (SiPM) for PET, with their high output capacitance, are known to require custom preamplifiers to optimize timing performance. In this paper, we describe simple alternative front-end electronics based on a commercial low-noise RF preamplifier and methods that have been implemented to achieve excellent timing resolution. Two radiation detectors with L(Y)SO scintillators coupled to Hamamatsu SiPMs (MPPC S10362-33-050C) and front-end electronics based on an RF amplifier (MAR-3SM+), typically used for wireless applications that require minimal additional circuitry, have been fabricated. These detectors were used to detect annihilation photons from a Ge-68 source and the output signals were subsequently digitized by a high speed oscilloscope for offline processing. A coincident resolving time (CRT) of 147 ± 3 ps FWHM and 186 ± 3 ps FWHM with 3 × 3 × 5 mm3 and with 3 × 3 × 20 mm3 LYSO crystal elements were measured, respectively. With smaller 2 × 2 × 3 mm3 LSO crystals, a CRT of 125 ± 2 ps FWHM was achieved with slight improvement to 121 ± 3 ps at a lower temperature (15° C). Finally, with the 20 mm length crystals, a degradation of timing resolution was observed for annihilation photon interactions that occur close to the photosensor compared to shallow depth-of-interaction (DOI). We conclude that commercial RF amplifiers optimized for noise, besides their ease of use, can produce excellent timing resolution comparable to best reported values acquired with custom readout electronics. On the other hand, as timing performance degrades with increasing photon DOI, a head-on detector configuration will produce better CRT than a side-irradiated setup for longer crystals.

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

2013-02-01

26

Optimizing timing performance of silicon photomultiplier-based scintillation detectors.  

PubMed

Precise timing resolution is crucial for applications requiring photon time-of-flight (ToF) information such as ToF positron emission tomography (PET). Silicon photomultipliers (SiPM) for PET, with their high output capacitance, are known to require custom preamplifiers to optimize timing performance. In this paper, we describe simple alternative front-end electronics based on a commercial low-noise RF preamplifier and methods that have been implemented to achieve excellent timing resolution. Two radiation detectors with L(Y)SO scintillators coupled to Hamamatsu SiPMs (MPPC S10362-33-050C) and front-end electronics based on an RF amplifier (MAR-3SM+), typically used for wireless applications that require minimal additional circuitry, have been fabricated. These detectors were used to detect annihilation photons from a Ge-68 source and the output signals were subsequently digitized by a high speed oscilloscope for offline processing. A coincident resolving time (CRT) of 147 ± 3 ps FWHM and 186 ± 3 ps FWHM with 3 × 3 × 5 mm(3) and with 3 × 3 × 20 mm(3) LYSO crystal elements were measured, respectively. With smaller 2 × 2 × 3 mm(3) LSO crystals, a CRT of 125 ± 2 ps FWHM was achieved with slight improvement to 121 ± 3 ps at a lower temperature (15° C). Finally, with the 20 mm length crystals, a degradation of timing resolution was observed for annihilation photon interactions that occur close to the photosensor compared to shallow depth-of-interaction (DOI). We conclude that commercial RF amplifiers optimized for noise, besides their ease of use, can produce excellent timing resolution comparable to best reported values acquired with custom readout electronics. On the other hand, as timing performance degrades with increasing photon DOI, a head-on detector configuration will produce better CRT than a side-irradiated setup for longer crystals. PMID:23369872

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

2013-01-31

27

Optimizing timing performance of silicon photomultiplier-based scintillation detectors  

PubMed Central

Precise timing resolution is crucial for applications requiring photon time-of-flight (ToF) information such as ToF positron emission tomography (PET). Silicon photomultipliers (SiPM) for PET, with their high output capacitance, are known to require custom preamplifiers to optimize timing performance. In this paper, we describe simple alternative front-end electronics based on a commercial low-noise RF preamplifier and methods that have been implemented to achieve excellent timing resolution. Two radiation detectors with L(Y)SO scintillators coupled to Hamamatsu SiPMs (MPPC S10362–33-050C) and front-end electronics based on an RF amplifier (MAR-3SM+), typically used for wireless applications that require minimal additional circuitry, have been fabricated. These detectors were used to detect annihilation photons from a Ge-68 source and the output signals were subsequently digitized by a high speed oscilloscope for offline processing. A coincident resolving time (CRT) of 147 ± 3 ps FWHM and 186 ± 3 ps FWHM with 3 × 3 × 5 mm3 and with 3 × 3 × 20 mm3 LYSO crystal elements were measured, respectively. With smaller 2 × 2 × 3 mm3 LSO crystals, a CRT of 125 ± 2 ps FWHM was achieved with slight improvement to 121 ± 3 ps at a lower temperature (15°C). Finally, with the 20 mm length crystals, a degradation of timing resolution was observed for annihilation photon interactions that occur close to the photosensor compared to shallow depth-of-interaction (DOI). We conclude that commercial RF amplifiers optimized for noise, besides their ease of use, can produce excellent timing resolution comparable to best reported values acquired with custom readout electronics. On the other hand, as timing performance degrades with increasing photon DOI, a head-on detector configuration will produce better CRT than a side-irradiated setup for longer crystals.

Yeom, Jung Yeol; Vinke, Ruud

2013-01-01

28

Improved Scintillator Materials for Compact Electron Antineutrino Detectors  

SciTech Connect

Developments in the fields of chemistry and materials science provide new components that hold the potential to improve the performance of liquid scintillation electron antineutrino detectors used for the monitoring of nuclear reactors. New compounds can provide for more efficient, stable, and safer operation of these detectors. Current detectors and their detector materials raise issues regarding size, quantum efficiency, stability, and spatial resolution for the vertex detection. For compact detectors (1 m{sup 3} active volume) improvement of these issues with existing liquid scintillation cocktails can be obtained by means of developing stable and efficient neutron capture agents. These agents comprise of boron or lithium containing coordination compounds, in addition advances in fluorescence detection technologies and optimization of solvent characteristics can improve the overall efficiency. Focus points of the new detector material design are to enable a compact, robust, and direction sensitive electron antineutrino detector.

Dijkstra, Peter; Wortche, Heinrich J. [INCAS3 (Innovative Centre for Advanced Sensors and Sensor Systems), P.O. Box 797, 9400AT, Assen (Netherlands); Browne, Wesley R. [Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)

2011-04-27

29

Improved Scintillator Materials for Compact Electron Antineutrino Detectors  

NASA Astrophysics Data System (ADS)

Developments in the fields of chemistry and materials science provide new components that hold the potential to improve the performance of liquid scintillation electron antineutrino detectors used for the monitoring of nuclear reactors. New compounds can provide for more efficient, stable, and safer operation of these detectors. Current detectors and their detector materials raise issues regarding size, quantum efficiency, stability, and spatial resolution for the vertex detection. For compact detectors (1 m3 active volume) improvement of these issues with existing liquid scintillation cocktails can be obtained by means of developing stable and efficient neutron capture agents. These agents comprise of boron or lithium containing coordination compounds, in addition advances in fluorescence detection technologies and optimization of solvent characteristics can improve the overall efficiency. Focus points of the new detector material design are to enable a compact, robust, and direction sensitive electron antineutrino detector.

Dijkstra, Peter; Wortche, Heinrich J.; Browne, Wesley R.

2011-04-01

30

Design and Construction Elements for Scintillating Fibre Tracking Detectors  

NASA Astrophysics Data System (ADS)

In many nuclear and particle physics experiments, it is necessary to ascertain precise information about a particle's trajectory, or its position at specific locations (as a means for then determining angle or momentum). A common way to determine this information is by using a scintillating fibre tracker, a device that relies on scintillation light from ionizing charged particles (such as electrons or protons) within scintillating fibres, and guiding the produced scintillation light through standard fibre optics to determine which scintillating fibre detected the particle. This thesis discusses, and presents results for technical issues associated with designing and constructing such a detector: (1) adjacent scintillating fibre-to-fibre cross-talk, and (2) the effect on light transmission of the combination of different fibre-end finishes and clear-to-scintillating fibre optical couplants. These results will be directly incorporated into the construction of a scintillating fibre coordinate detector to be built for future experiments at Jefferson Lab's Hall A in Newport News, VA, USA.

Sharpe, Jason Ray

31

A photon transport model code for use in scintillation detectors  

Microsoft Academic Search

A Monte Carlo code, PHOTRACK, has been written to simulate the behaviour of light photons in scintillation detectors, with and without light guides. It has been tested by reproducing the results of other workers, and then used in preliminary studies of a small lithium glass neutron detector.

N Ghal-Eh; M. C Scott; R Koohi-Fayegh; M. F Rahimi

2004-01-01

32

Investigation of Plastic Scintillator Detector Configurations for Neutron Studies  

NASA Astrophysics Data System (ADS)

Plastic scintillation products are widely used for detecting nuclear radiation. Measurements of the response of plastic scintillator detectors to different radiations are important in the design phase of a detection system and as an initial input in Monte Carlo simulation codes. We performed test measurements of the light response, attenuation length, time and position resolution, and detection efficiency of Bicron BC408 plastic scintillator. Four plastic scintillator bars of dimensions 2.9x2.9x60 cm^3 and 5x5x200 cm^3 have been developed to be used in (d,n) and beta-delayed neutron studies. The detectors were constructed with different reflecting materials, optical couplings and photomultiplier tube assemblies. Measurements are compared with predictions from the Monte Carlo simulation code GEANT4. Details of the experimental configuration and results will be presented.

Matei, Catalin; Bardayan, D. W.; Blackmon, J. C.; Howard, J. A.; Cizewski, J. A.; O'Malley, P. D.; Pain, S. D.; Peters, W. A.; Grzywacz, R. K.; Jones, K. L.; Liddick, S. N.

2007-10-01

33

New approaches in medical imaging using plastic scintillating detectors  

Microsoft Academic Search

A small animal imaging camera was built in our laboratory, using-fast plastic scintillating detectors (tau = 2-4 ns) and position sensitive photomultipliers (Hamamatsu) digitized using flash ADCs. Pinhole collimators were used for 125I imaging to achieve submillimeter resolution with scintillating plates of 28 mm radius and 1.5 mm thickness. A high resolution PET module was constructed with arrays of 1.0

P. V. Kulkarni; J. A. Anderson; P. P. Antich; J. O. Prior; Y. Zhang; J. Fernando; A. Constantinescu; N. C. Goomer; R. W. Parkey; E. Fenyves; R. C. Chaney; S. C. Srivastava; L. F. Mausner

1993-01-01

34

Response of gamma scintillation detectors for field survey use  

Microsoft Academic Search

Gamma scintillation spectra were obtained with several sizes of NaI( Tl) crystal, Pilot B plastic, and liquid detectors which were immersed in solutions of gamma-emitting nuclides contained in a 2,3OO-gal tank. The count rates for gamma photons in the Mev energy range were proportional to detector volumes. Integral count rates with plastic and liquid detectors were, respectively, 39% and 335%

CHARLES M. PROCTOR; ANDREW R. LOWREY; EMANUEL PAPADOPULOS; JOHN R. PENNING

1962-01-01

35

Light output of EJ228 scintillation neutron detectors.  

PubMed

The light output of neutron detectors based on the plastic scintillator EJ228 is studied as a function of neutron energy using a time tagged (252)Cf source. Calibration of the light output scale is performed by fitting the experimental distribution of Compton scattering events of photons from a (22)Na source with a response function obtained by Gaussian smearing of the predicted line-shape. The light output curve as well as the pulse height resolution for the EJ228 scintillators is very close (within 5%) to those recently reported for NE213 type organic liquid scintillators. PMID:21075000

Stevanato, L; Fabris, D; Hao, Xin; Lunardon, M; Moretto, S; Nebbia, G; Pesente, S; Sajo-Bohus, L; Viesti, G

2010-10-29

36

The Monte-Carlo simulation on a scintillator neutron detector  

NASA Astrophysics Data System (ADS)

A simulation of the properties of the shifting scintillator neutron detector using 6LiF/ZnS(Ag) scintillation screens is performed. The simulation results show that the light attenuation length of standard BC704 scintillator is about 0.65 mm. Its thermal neutron detection efficiency, gamma sensitivity and intrinsic spatial resolution can achieve around 50.0%, 10-5 and 0.18 mm (along X-axis) respectively. For the detector, air coupling position resolution is better than the silicone oil coupling. Some of the simulation results are compared with experimental results. They are in agreement. This work will be helpful for constructing neutron detector for high intensity powder diffractometer at Chinese spallation neutron source.

Wu, Chong; Tang, Bin; Sun, ZhiJia; Zhang, Qiang; Yang, Zhen; Luo, Wei; Wang, Tuo

2013-10-01

37

Design of organic scintillators for non-standard radiation field dosimetry: Experimental setup.  

PubMed

This paper describes an experimental setup designed for sensing the luminescent light coming from an organic plastic scintillator stimulated with ionizing radiation. This device is intended to be a part of a complete dosimeter system for characterization of small radiation fields which is the project of the doctoral thesis of the medical physicist at the Radiation Oncology facility of Hospital San Vicente Fundación in conjunction with the Universidad de Antioquia of Medellín Colombia. Some preliminary results predict a good performance of the unit, but further studies must be conducted in order to have a completed evaluation of the system. This is the first step in the development of an accuracy tool for measurement of non-standard fields in the Radiotherapy or Radiosurgery processes. PMID:24110369

Norman H, Machado R; Maximiliano, Trujillo T; Javier E, Garcia G; Diana C, Narvaez G; Paula A, Marin M; Robinson A, Torres V

2013-07-01

38

New detectors for ?-ray spectroscopy and imaging, based on scintillators coupled to silicon drift detectors  

NASA Astrophysics Data System (ADS)

Silicon Drift Detectors (SDDs) have been recently employed as detectors of scintillation light for ?-ray spectroscopy and imaging applications. Compared to conventional Photo Multiplier Tubes (PMTs), these devices offer the higher quantum efficiency to the scintillation light, typical of a silicon detector. Moreover, due to the low value of output capacitance, a SDD is characterized by a lower electronics noise with respect to a conventional silicon photodiode. This feature allows a detector based on the CsI(Tl)-SDD architecture to reach high energy and position resolution in gamma detection. In this work we present the results obtained in the development of the first prototypes of gamma detectors for energy measurements (single scintillator-SDD unit) and 1D or 2D position measurements (single scintillator coupled to an array of SDDs).

Fiorini, C.; Longoni, A.; Perotti, F.

2000-11-01

39

Light attenuators for plastic scintillation detectors  

Microsoft Academic Search

The need for light filters to attenuate flashes in plastic scintillators arose in designing apparatus for measurement of the charge composition of primary cosmic rays. Eight photomultipliers, each of which required a light filter, were arranged horizontally over a length of 50 cm in each of 10 rows of an ionization calorimeter. It was required that the absorption coefficients of

Tretyakova; Ch. A

1987-01-01

40

Towards an understanding of nonlinearity in scintillator detector materials  

NASA Astrophysics Data System (ADS)

It has been known for more than 50 years that the light emitted by a scintillator under high-energy excitation (gamma, alpha, proton) is not always proportional to the amount of absorbed energy. The deviation from the linearity of luminosity versus absorbed energy is known as nonproportionality. In addition to its academic interest, this phenomenon has been considered central for scintillator development due to its implication in the limitation of achievable detector performance. Although non-proportional response was studied intensively during the second part of the 20th century, the understanding of its origin and implications on scintillator performance are mainly qualitative. Research in the 1960s uncovered a correlation between proportional response and ionization density, while in the 1980s nonproportionality was proposed as the main reason of energy resolution deviation from the counting statistics limit. It is only recently that the bridge between qualitative and quantitative understanding has been crossed, mainly driven by the large effort undertaken to discover new high-resolution scintillators. Developing such detector materials prompted efforts to gain a deeper understanding of the microscopic processes involved in scintillation mechanisms and so in nonproportionality. In this manuscript, the phenomenology of past and present understanding of non-proportional response will be reviewed. Based on recent experimental, computational and theoretical works, the relation between nonlinear response and energy resolution degradation will be addressed. Finally, the relation between material parameters and proportionality will be evaluated. These recent works are leading towards a deeper understanding of nonlinearity in scintillator detector materials and should result in the development of new high performance scintillator materials.

Bizarri, G.; Moses, W. W.; Payne, S. A.; Williams, R. T.

2011-09-01

41

Calibration of Scintillation Detectors Using a DT Generator  

Microsoft Academic Search

The Nuclear Materials Identification System (NMIS) is in use domestically for the performance of non-destructive assays of fissile material. These procedures involve the fast correlation measurement of neutrons and gamma rays from fission using organic scintillation detectors. In active measurements, an external source of neutrons is used to induce fission in the sample to be analyzed. For measurement analysis and

Jarrod D. Edwards; Sara A. Pozzi; John T. Mihalczo

2004-01-01

42

A scintillating bar tracking detector for the ASACUSA -  

Microsoft Academic Search

The ASACUSA trap group aim is the production and the study of antihydrogen at the CERN AD (Antiproton Decelerator). After the end of 2007, when the first results were obtained, it was evident that to improve the trapping efficiency of the antiprotons, their annihilation position within the electromagnetic trap had to be reconstructed. A scintillating bar detector, capable of tracking

V. Mascagna; D. Bolognini; M. Corradini; M. Leali; D. Lietti; E. Lodi Rizzini; M. Prest; L. Stoppani; E. Vallazza; L. Venturelli; N. Zurlo

2010-01-01

43

Active Inspection of Nuclear Materials Using 4He Scintillation Detectors  

NASA Astrophysics Data System (ADS)

The detection of fissionable materials by neutron and high-energy photon active interrogation methods is explored using 4He scintillation detectors to search for prompt and delayed neutron signature. The low electron density of 4He in addition to its pulse shape discrimination capability allows strong rejection of gamma radiation. For the detection of the prompt neutron signatures, this capability is important as the signal produced by induced fission is accompanied by intense gamma radiation. The nanosecond time resolution of 4He scintillation detectors can be used for time-of-flight measurements aimed at determining the energy of the emitted neutrons. For delayed neutron detection, the insensitivity to the low energy neutrons present from non-signal reactions is inherent. Unlike detectors requiring a moderator, this technology can easily be collimated to reduce sensitivity to neutrons from outside the field of interest. The performance of the detectors for these applications is studied using GEANT4 computer modeling, based on measured detector parameters. A comparison is made with technologies typically used for these applications, i.e. heavily shielded organic scintillators for prompt neutron detection and Cd-lined 3He neutron detectors for the detection of delayed neutrons.

Davatz, G.; Chandra, R.; Gendotti, U.; Howard, A.

2011-12-01

44

The Homestake Large Area Scintillation Detector and cosmic ray telescope  

NASA Astrophysics Data System (ADS)

The above-ground and underground components of the Large Area Scintillation Detector (LASD) and cosmic-ray telescope being constructed at Homestake are described, and its use for cosmic-ray observations is discussed. The underground LASD comprises 200 0.3 x 0.3 x 8-m teflon-lined PVC scintillator elements containing mineral-oil-based scintillator and viewed by two 5-inch photomultiplier tubes each, with element time and spatial resolution 1.3 ns and 15 cm, respectively, and muon background flux 1100/sq m yr. The elements are arranged in a hollow 8 x 8 x 16-m box surrounding the Brookhaven Cl-37 solar-neutrino detector at a depth of 4850 ft. The surface air-shower array consists of 100 3-sq-m scintillation cells (4 x 8 x 2-ft reinforced-concrete boxes containing styrofoam insulation and 4-inch-deep scintillator viewed by two 5-inch photomultiplier tubes) deployed over an area of about 0.8 sq km above the LASD. The combined instruments can study the multiplicity and transverse-momentum distributions of cosmic-ray muons, the elemental composition of the primary cosmic rays, and related phenomena.

Cherry, M. L.; Corbato, S.; Kieda, D.; Lande, K.; Lee, C. K.

45

Single-photoelectron noise reduction in scintillation detectors  

SciTech Connect

The 1994--95 search at SLAC for mulicharged particles used four 21 {times} 21 {times} 130-cm{sup 3} Bicron 408 scintillation counters to detect a signal at the single-photoelectron level. The competing noise requiring minimization was due to a combination of PM tube (8-inch Thorne EMI 9353KA) afterpulsing and ambient radiation-induced scintillator luminescence. A very slow decay (> 30 {mu}s) component was observed and received particular attention. Efforts to reduce the SPE noise included photomultiplier tube base modifications, detector shielding and cooling, signal amplification, and veto procedures.

Marvin, T.P. [Southern Oregon State College, Ashland, OR (United States); The SLAC mQ Collaboration

1995-10-01

46

Bismuth germanate as a potential scintillation detector in positron cameras.  

PubMed

Timing and energy resolutions of the bismuth germanate (Bi4Ge3O12) scintillation crystals were studied, with particular respect to a positron-camera application. In comparison with the NaI(Tl) system, the detection efficiency for annihilation radiation is more than triple, and coincidence detection efficiency is more than ten times as good. This paper explores the properties of the new scintillator material and their bearing on the spatial resolution and the efficiency of coincidence detection in positron cameras with stationary ring detectors. PMID:874173

Cho, Z H; Farukhi, M R

1977-08-01

47

Improved Scintillator Materials For Compact Electron Antineutrino Detectors  

NASA Astrophysics Data System (ADS)

Recent developments provide new components holding the potential to improve the performance of liquid scintillation electron antineutrino detectors used as nuclear reactors monitors. Current systems raise issues regarding size, quantum efficiency, stability, and spatial resolution of the vertex detection. For compact detectors (1 m3 active volume) improving these issues is possible by developing stable and efficient boron or lithium containing NCA. In addition, advances in fluorescence detection technologies and optimization of solvent characteristics can improve the overall efficiency. Focus points of material design are to enable a compact, robust, and direction sensitive detector.

Dijkstra, Peter; Wortche, Heinrich J.; Browne, Wesley R.

2012-08-01

48

Pulse-shape discrimination in NE213 liquid scintillator detectors  

NASA Astrophysics Data System (ADS)

The 16-channel fast stretcher BaFPro module, originally developed for processing signals of Barium Fluoride scintillators, has been modified to make a high performing analog pulse-shape analysis of signals from the NE213 liquid scintillators of the EDEN neutron detector array. The module produces two Gaussian signals, whose amplitudes are proportional to the height of the fast component of the output light and to the total energy deposited into the scintillator, respectively. An in-beam test has been performed at INFN-LNS (Italy) demonstrating a low detection threshold, a good pulse-shape discrimination even at low energies and a wide dynamic range for the measurement of the neutrons energy.

Cavallaro, M.; Tropea, S.; Agodi, C.; Assié, M.; Azaiez, F.; Boiano, C.; Bondì, M.; Cappuzzello, F.; Carbone, D.; De Napoli, M.; de Séréville, N.; Foti, A.; Linares, R.; Nicolosi, D.; Scarpaci, J. A.

2013-02-01

49

New approaches in medical imaging using plastic scintillating detectors  

NASA Astrophysics Data System (ADS)

A small animal imaging camera was built in our laboratory, using-fast plastic scintillating detectors (? = 2-4 ns) and position sensitive photomultipliers (Hamamatsu) digitized using flash ADCs. Pinhole collimators were used for 125I imaging to achieve submillimeter resolution with scintillating plates of 28 mm radius and 1.5 mm thickness. A high resolution PET module was constructed with arrays of 1.0 mm diameter plastic scintillating fibers. The feasibility of high resolution imaging was demonstrated by the study of brain blood flow in a rat using 125I IMP in single photon detection mode and with 64Cu PTSM by using PET mode. Construction of single photon and positron emission tomographic imaging systems for small animals and subsequently for human imaging is in progress.

Kulkarni, P. V.; Anderson, J. A.; Antich, P. P.; Prior, J. O.; Zhang, Y.; Fernando, J.; Constantinescu, A.; Goomer, N. C.; Parkey, R. W.; Fenyves, E.; Chaney, R. C.; Srivastava, S. C.; Mausner, L. F.

1993-06-01

50

Direct photon-counting scintillation detector readout using an SSPM  

NASA Astrophysics Data System (ADS)

Gamma-ray detector technologies, capable of providing adequate energy information, use photomultiplier tubes (PMTs) or silicon avalanche photodiodes to detect the light pulse from a scintillation crystal. A new approach to detect the light from scintillation materials is to use an array of small photon counting detectors, or a “detector-on-a-chip” based on a novel “Solid-state Photomultiplier” (SSPM) concept. A CMOS SSPM coupled to a scintillation crystal uses an array of CMOS Geiger photodiode (GPD) pixels to collect light and produce a signal proportional to the energy of the radiation. Each pixel acts as a binary photon detector, but the summed output is an analog representation of the total photon intensity. We have successfully fabricated arrays of GPD pixels in a CMOS environment, which makes possible the production of miniaturized arrays integrated with the detector electronics in a small silicon chip. This detector technology allows for a substantial cost reduction while preserving the energy resolution needed for radiological measurements. In this work, we compare designs for the SSPM detector. One pixel design achieves maximum detection efficiency (DE) for 632-nm photons approaching 30% with a room temperature dark count rate (DCR) of less than 1 kHz for a 30-?m-diameter pixel. We characterize after pulsing and optical cross talk and discuss their effects on the performance of the SSPM. For 30-?m diameter, passively quenched CMOS GPD pixels, modeling suggests that a pixel spacing of approximately 90 ?m optimizes the SSPM performance with respect to DE and cross talk.

Stapels, Christopher J.; Squillante, Michael R.; Lawrence, William G.; Augustine, Frank L.; Christian, James F.

2007-08-01

51

A ruggedized ZnS(Ag)/epoxy alpha scintillation detector  

NASA Astrophysics Data System (ADS)

An alpha scintillation survey instrument has been developed which is more rugged and efficient than conventional alpha scintillation detectors that use aluminized Mylar **** Mylar is a trademark of E.I. du Pont de Nemours & Co., Inc., Wilmington, DE, USA. radiation entrance windows. This new detector consists of a mixture of ZnS(Ag) phosphor and optically transparent epoxy. The scintillator mixture is poured into a preformed mold to provide a thin layer of phosphor after the particles settle to the clear epoxy surface. After partial curing, an optically transparent light pipe is coupled to the ZnS(Ag)/epoxy film by using an additional thin epoxy layer, forming a monolithic scintillator assembly. Experimental results indicate that the new probe is 44% efficient (2?) for a large-area 239Pu alpha source; resistant to scratches, tears, and corrosives; watertight; and temperature independent between -20°C and 54°C.

McElhaney, S. A.; Ramsey, J. A.; Bauer, M. L.; Chiles, M. M.

1990-12-01

52

A new compact position-sensitive PMT for scintillation detectors  

Microsoft Academic Search

A new compact position-sensitive photomultiplier tube (PS-PMT), Hamamatsu R7600-C12, has been developed for scintillation detectors. The PS-PMT has 11 stages of metal channel dynodes [2] and 6(X)+6(Y) crossed plate anodes in a 25.7 mm square×20 mm high metal can package, where the photo-sensitive area is 22 mm square. The performance of the PS-PMT was evaluated in terms of applicability to

S. Nagai; M. Watanabe; H. Shimoi; H. Liu; Y. Yoshizawa

1999-01-01

53

High Count Rate Neutron Spectrometry With Liquid Scintillation Detectors  

Microsoft Academic Search

Liquid scintillation detectors are widely used in nuclear\\/high-energy physics and nuclear fusion for spectral measurements in mixed radiation fields due to their compactness, fast response and neutron\\/gamma discrimination capabilities. The use of response functions evaluated for the specific system and of appropriate methods of data analysis allows such systems to be used as broadband spectrometers for photons and neutrons. System

Daniele Marocco; Francesco Belli; Basilio Esposito; Marco Riva; Luca Giacomelli; Marcel Reginatto; Kai Tittelmeier; Andreas Zimbal

2009-01-01

54

Characterisation of spectral performance of pixellated X-ray imaging detectors in a microscopy setup  

NASA Astrophysics Data System (ADS)

In order to achieve energy resolved X-ray imaging with small pixel resolution, physical processes in the detector material such as fluorescence and charge sharing must be considered. This paper presents characterisation measurements performed with an X-ray microscopy setup for energy resolved imaging. The microscopy setup consists of a nanofocus X-ray source capable of 160 kV anode voltage, ESRF-type collimating slits and Medipix2 detectors. The detector systems developed in the Medipix collaboration are capable of energy resolved imaging. The measurements were performed by scanning an energy window through the spectrum. In this paper we have considered detectors made of Si, GaAs and CdTe for use in the microscopy setup. Both measurements and theoretical simulations are considered. For high X-ray energies, it is essential to consider fluorescence from the shielding and Compton scattering in silicon detectors.

Norlin, Börje; Fröjdh, Christer

2009-08-01

55

Optical scattering lengths in large liquid-scintillator neutrino detectors  

SciTech Connect

For liquid-scintillator neutrino detectors of kiloton scale, the transparency of the organic solvent is of central importance. The present paper reports on laboratory measurements of the optical scattering lengths of the organic solvents phenylxylylethane, linear alkylbenzene (LAB), and dodecane, which are under discussion for next-generation experiments such as SNO+ (Sudbury Neutrino Observatory), HanoHano, or LENA (Low Energy Neutrino Astronomy). Results comprise the wavelength range of 415-440 nm. The contributions from Rayleigh and Mie scattering as well as from absorption/re-emission processes are discussed. Based on the present results, LAB seems to be the preferred solvent for a large-volume detector.

Wurm, M.; Feilitzsch, F. von; Goeger-Neff, M.; Hofmann, M.; Lewke, T.; Meindl, Q.; Moellenberg, R.; Oberauer, L.; Potzel, W.; Tippmann, M.; Todor, S.; Winter, J. [Physik-Department E15, Technische Universitaet Muenchen, James-Franck-Str., D-85748 Garching (Germany); Lachenmaier, T.; Traunsteiner, C. [Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstr. 2, D-85748 Garching (Germany); Undagoitia, T. Marrodan [Physik-Department E15, Technische Universitaet Muenchen, James-Franck-Str., D-85748 Garching (Germany); Physik-Institut, Universitaet Zuerich, Winterthurstr. 189, CH-8057 Zuerich (Switzerland)

2010-05-15

56

Fission ?-RAY Measurements with Lanthanum Halide Scintillation Detectors  

NASA Astrophysics Data System (ADS)

In a recent experiment, performed at the 10 MW research reactor at the Institute of Isotopes (IKI) in Budapest, the emission of prompt ?-rays from the cold-neutron induced fission of 236U* was measured. For that purpose four cerium-doped lanthanum halide scintillation detectors were employed and found very useful in order to distinguish between ?-rays from different reactions. Although data analysis is not completed yet, we could show that these novel detectors indeed provide the means towards new and more precise input data necessary for the modeling of ?-heating in nuclear reactors.

Oberstedt, A.; Billnert, R.; Karlsson, J.; Göök, A.; Oberstedt, S.; Hambsch, F.-J.; Ledoux, X.; Marmouget, J.-G.; Belgya, T.; Kis, Z.; Szentmiklosi, L.; Takács, K.; Martinez-Perez, T.; Cano-Ott, D.

2011-10-01

57

Gamma-Beta-Neutron Detectors Set-Up at ALTO  

SciTech Connect

A multi detection system consisted of 90 {sup 3}He counters, gamma detector and beta detector has been installed at beamline of the accelerator complex ALTO. The system allows performing direct measurements of probability of delayed neutron emission from spontaneous fission fragments. A trial experiment was carried out to test the detection system created.

Testov, D.; Penionzhkevich, Yu.; Smirnov, V.; Sokol, E. [Flerov laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna (Russian Federation); Ancelin, S.; Ibrahim, F.; Niikura, M.; Tastet, B.; Verney, D. [Institute de Physique Nucleaire d'Orsay (France)

2010-04-30

58

Characterizing quantum-dot-doped liquid scintillator for applications to neutrino detectors  

NASA Astrophysics Data System (ADS)

Liquid scintillator detectors are widely used in modern neutrino studies. The unique optical properties of semiconducting nanocrystals, known as quantum dots, offer intriguing possibilities for improving standard liquid scintillator, especially when combined with new photo-detection technology. Quantum dots also provide a means to dope scintillator with candidate isotopes for neutrinoless double beta decay searches. In this work, the first studies of the scintillation properties of quantum-dot-doped liquid scintillator using both UV light and radioactive sources are presented.

Winslow, L.; Simpson, R.

2012-07-01

59

Development of scintillation detectors based on avalanche microchannel photodiodes  

NASA Astrophysics Data System (ADS)

Avalanche Microchannel PhotoDiodes (AMPDs) are solid state photodetectors with high internal gain and a density of independent channels up to 104/mm2. They are potential substitutes for photomultiplier tubes in a wide variety of applications in nuclear physics and nuclear medicine, especially when fine segmentation of the detectors and their operation in high magnetic fields is required. In this work, we study the performance of a detector based on a LYSO (2×2×10 mm3) scintillation crystal and AMPD at detection of 511 keV ?-quanta. The detector shows linear energy response, an energy resolution of ˜12%, and sub-nanosecond time resolution. These characteristics are encouraging for using AMPDs in detector systems of positron emission tomographs (PET) of the next generation.

Britvitch, I.; Lorenz, E.; Olshevski, A.; Renker, D.; Sadygov, Z.; Scheuermann, R.; Stoykov, A.; Werner, A.; Zheleznykh, I.

2007-02-01

60

A Geant4 simulation package for the TASISpec experimental detector setup  

NASA Astrophysics Data System (ADS)

The experimental detector setup TASISpec (TA SCA in Small Image mode Spectroscopy) comprises composite Ge- and highly segmented Si-detectors. The setup is constructed to provide multi-coincidence spectroscopic data between ?-rays, X-rays, conversion electrons, fission fragments, and ?-particles for heavy and superheavy elements (Z?100).The full array has been virtually constructed using the Geant4 simulation toolkit. The simulations will not only be used to explore the possibilities of the detector setup itself. More important, however, they will also shed light on the nuclear structure of the heaviest elements. This can be done by comparing the simulated detector response of complex decay modes with the experimental data. Such an iterative or "self-consistent" way to understand experimental observables will provide more reliability when disentangling the data and deducing experimental decay schemes.

Sarmiento, L. G.; Andersson, L.-L.; Rudolph, D.

2012-03-01

61

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

DOEpatents

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.

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

62

6Li foil scintillation sandwich thermal neutron detector  

NASA Astrophysics Data System (ADS)

Increasing needs for neutron detection and limited supply of 3He have led to the need for replacement neutron detection technology. This paper presents the design and initial results for a neutron detector (6Li foil scintillator sandwich) that uses lithium metal foil to detect thermal neutrons. The reaction products, primarily triton, deposit most of their energy in thin scintillator films and create light pulses. Gamma rays can deposit only a small amount of energy in the thin films and so produce only very small light pulses. Lithium is preferable to boron in this application because triton escapes from lithium more easily than does the alpha particle from boron, allowing the use of thicker films and hence greater efficiency. In addition, triton has a higher light output in the scintillator than the boron alpha particle. Lithium metal is preferable to a lithium compound, such as lithium fluoride, because the number of tritons that escape from the metal is greater for the same amount of lithium. Monte Carlo simulations show that good efficiency values can be achieved with reasonably sized detectors, values that are greater than that of comparable 3He systems for portal monitors. In addition, simulations of a neutron coincidence counting concept show high counting efficiency and short die-away time (16 ?s), which imply better performance than that of the high-level neutron coincidence counter (HLNCC)-II. Initial experimental measurements on a prototype detector using alpha particles (having similar light output to the expected tritons) show good light collection and transport properties.

Ianakiev, K. D.; Swinhoe, M. T.; Favalli, A.; Chung, K.; MacArthur, D. W.

2011-10-01

63

Multi-layer scintillation detector for the MOON double beta decay experiment: Scintillation photon responses studied by a prototype detector MOON1  

Microsoft Academic Search

An ensemble of multi-layer scintillators is discussed as an option of the\\u000ahigh-sensitivity detector Mo Observatory Of Neutrinos (MOON) for spectroscopic\\u000ameasurements of neutrino-less double beta decays. A prototype detector MOON-1,\\u000awhich consists of 6 layer plastic-scintillator plates, was built to study the\\u000asensitivity of the MOON-type detector. The scintillation photon collection and\\u000athe energy resolution, which are key elements

H. Nakamura; P. Doe; H. Ejiri; S. R. Elliott; J. Engel; M. Finger; M. Finger. Jr; K. Fushimi; V. Gehman; A. Gorin; M. Greenfield; V. H. Hai; R. Hazama; K. Higa; T. Higashiguchi; K. Ichihara; Y. Ikegami; J. Imoto; H. Ishii; T. Itahashi; H. Kaneko; P. Kavitov; H. Kawasuso; V. Kekelidze; K. Matsuoka; T. Mizuhashi; D. Noda; M. Nomachi; K. Onishi; T. Ogama; A. Para; R. G. H. Robertson; M. Sakamoto; T. Sakiuchi; Y. Samejima; Y. Shichijo; T. Shima; Y. Shimada; G. Shirkov; A. Sissakian; M. Slunecka; Y. Sugaya; A. Titov; M. Uenoyama; S. Umehara; A. Urano; V. Vatulin; V. Voronov; J. F. Wilkerson; D. I. Will; K. Yasuda; S. Yoshida; M. Yoshihuku

2006-01-01

64

Scintillating plastic optical fiber radiation detectors in high energy particle physics  

SciTech Connect

We describe the application of scintillating optical fiber in instrumentation for high energy particle physics. The basic physics of the scintillation process in polymers is discussed first and then we outline the fundamentals of scintillating fiber technology. Fiber performance, optimization, and characterization measurements are given. Detector applications in the areas of particle tracking and particle energy determination are then described. 13 refs., 12 figs.

Bross, A.D.

1991-10-26

65

Comparison of LuYAP, LSO, and BGO as scintillators for high resolution PET detectors  

Microsoft Academic Search

For high resolution positron emission tomographs based on scintillation detectors a fast, dense, and bright scintillator is required. A sample of a new scintillator, Lu0.8Y0.2AlO3:Ce (LuYAP) with a density of 7.7 g\\/cm3 and a scintillation decay time of 20 and 160 ns is compared with LSO and BGO crystals of the same size to estimate the potential of the crystal

Simone Weber; Daniela Christ; Marcel Kurzeja; Ralf Engels; Guenter Kemmerling; Horst Halling

2003-01-01

66

3D position estimation using an artificial neural network for a continuous scintillator PET detector  

NASA Astrophysics Data System (ADS)

Continuous crystal based PET detectors have features of simple design, low cost, good energy resolution and high detection efficiency. Through single-end readout of scintillation light, direct three-dimensional (3D) position estimation could be another advantage that the continuous crystal detector would have. In this paper, we propose to use artificial neural networks to simultaneously estimate the plane coordinate and DOI coordinate of incident ? photons with detected scintillation light. Using our experimental setup with an ‘8 + 8’ simplified signal readout scheme, the training data of perpendicular irradiation on the front surface and one side surface are obtained, and the plane (x, y) networks and DOI networks are trained and evaluated. The test results show that the artificial neural network for DOI estimation is as effective as for plane estimation. The performance of both estimators is presented by resolution and bias. Without bias correction, the resolution of the plane estimator is on average better than 2 mm and that of the DOI estimator is about 2 mm over the whole area of the detector. With bias correction, the resolution at the edge area for plane estimation or at the end of the block away from the readout PMT for DOI estimation becomes worse, as we expect. The comprehensive performance of the 3D positioning by a neural network is accessed by the experimental test data of oblique irradiations. To show the combined effect of the 3D positioning over the whole area of the detector, the 2D flood images of oblique irradiation are presented with and without bias correction.

Wang, Y.; Zhu, W.; Cheng, X.; Li, D.

2013-03-01

67

3D position estimation using an artificial neural network for a continuous scintillator PET detector.  

PubMed

Continuous crystal based PET detectors have features of simple design, low cost, good energy resolution and high detection efficiency. Through single-end readout of scintillation light, direct three-dimensional (3D) position estimation could be another advantage that the continuous crystal detector would have. In this paper, we propose to use artificial neural networks to simultaneously estimate the plane coordinate and DOI coordinate of incident ? photons with detected scintillation light. Using our experimental setup with an '8 + 8' simplified signal readout scheme, the training data of perpendicular irradiation on the front surface and one side surface are obtained, and the plane (x, y) networks and DOI networks are trained and evaluated. The test results show that the artificial neural network for DOI estimation is as effective as for plane estimation. The performance of both estimators is presented by resolution and bias. Without bias correction, the resolution of the plane estimator is on average better than 2 mm and that of the DOI estimator is about 2 mm over the whole area of the detector. With bias correction, the resolution at the edge area for plane estimation or at the end of the block away from the readout PMT for DOI estimation becomes worse, as we expect. The comprehensive performance of the 3D positioning by a neural network is accessed by the experimental test data of oblique irradiations. To show the combined effect of the 3D positioning over the whole area of the detector, the 2D flood images of oblique irradiation are presented with and without bias correction. PMID:23399593

Wang, Y; Zhu, W; Cheng, X; Li, D

2013-02-11

68

Towards design and optimization of scintillation-detector systems: A Monte-Carlo simulation framework  

Microsoft Academic Search

A complete simulation framework that combines Monte Carlo simulation with the digital-signal-processing algorithms developed in-house is presented for designing and optimizing scintillation detector systems. The framework covers basic components of a practical scintillation detector system and includes all relevant physical processes. With the complete simulation individual physical factors that can affect the performance of a detector system, such as detector

Yong Kong; Guntram Pausch; Katja Roemer; Marcus Neuer; Cristina Plettner; Ralf Lentering; Juergen Stein

2010-01-01

69

Measurements of the electron dose distribution near inhomogeneities using a plastic scintillation detector  

Microsoft Academic Search

Accurate measurement of the electron dose distribution near an inhomogeneity is difficult with traditional dosimeters which themselves perturb the electron field. The authors tested the performance of a new high resolution, water-equivalent plastic scintillation detector which has ideal properties for this application. A plastic scintillation detector with a 1 mm diameter, 3 mm long cylindrical sensitive volume was used to

Carol M. Meger Wells; T. Rockwell Mackie; Matthew B. Podgorsak; Mark A. Holmes; Nikos Papanikolaou; Paul J. Reckwerdt; Joanna Cygler; David W. O. Rogers; Alex F. Bielajew; Daniel G. Schmidt

1994-01-01

70

Contamination monitors for nuclear power plants; Plastic scintillators vs. proportional detectors  

Microsoft Academic Search

This paper reports on trends in monitoring for radioactive material (contamination) on or in waste, tools, laundry and personnel at nuclear power stations which have been towards the increased use of large-area gas-flow proportional detectors and large plastic scintillators. Solid plastic scintillators can be made sensitive primarily to beta, gamma only, or both beta and gamma radiation. Proportional detectors can

E. Geiger; L. Phyfe; W. Fisher

1985-01-01

71

An approximation of the ideal scintillation detector line shape with a generalized gamma distribution  

NASA Astrophysics Data System (ADS)

An approximation of the real line shape of a scintillation detector with a generalized gamma distribution is proposed. The approximation describes the ideal scintillation line shape better than the conventional normal distribution. Two parameters of the proposed function are uniquely defined by the first two moments of the detector response.

Smirnov, O. Ju.

2008-10-01

72

Stabilizing scintillation detector systems: determination of the scintillator temperature exploiting the temperature dependence of the light pulse decay time  

Microsoft Academic Search

Scintillation detectors must tolerate a wide range of ambient temperatures and strong temperature slopes when used in outdoor applications. Such demanding conditions are typical for all homeland security applications. An effective and efficient detector stabilization compensating for temperature dependent gain shifts is essential to maintain energy calibration and resolution. Reliable, well established solutions are based on radioactive reference sources; however,

Guntram Pausch; J. Stein; N. Teofilov

2004-01-01

73

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

SciTech Connect

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.

Shao Yiping; Yao Rutao; Ma Tianyu [Department of Imaging Physics, University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 600, Houston, Texas 77030 (United States); Department of Nuclear Medicine, State University of New York at Buffalo, 105 Parker Hall, 3435 Main Street, Buffalo, New York 14214 (United States); Department of Nuclear Medicine, State University of New York at Buffalo, 105 Parker Hall, 3435 Main Street, Buffalo, New York 14214 and Department of Engineering Physics, Tsinghua University, Beijing, 100084 (China)

2008-12-15

74

Measuring fast neutrons with large liquid scintillation detector for ultra-low background experiments  

NASA Astrophysics Data System (ADS)

We developed a 12-liter volume neutron detector filled with the liquid scintillator EJ301 that measures neutrons in an underground laboratory where dark matter and neutrino experiments are located. The detector target is a cylindrical volume coated on the inside with reflective paint (95% reflectivity) that significantly increases the detector's light collection. We demonstrate several calibration techniques using point sources and cosmic-ray muons for energies up to 20 MeV for this large liquid scintillation detector. Neutron–gamma separation using pulse shape discrimination with a few MeV neutrons to hundreds of MeV neutrons is shown for the first time using a large liquid scintillator.

Zhang, C.; Mei, D.-M.; Davis, P.; Woltman, B.; Gray, F.

2013-11-01

75

Structural design of a high energy particle detector using liquid scintillator  

SciTech Connect

This thesis presents a design for a 10,000 ton liquid scintillator neutrino detector being considered for the MINOS project at Fermilab. Details of designing, manufacturing, and assembling the active detector components are presented. The detector consists of 1080 magnetized steel absorber planes alternating with 1080 active detector planes. Each active plane is made up of plastic extrusions divided into nearly 400 cells for positional resolution. Life tests on the plastic extrusions determine their feasibility for containing the scintillator. The extrusions are sealed at the bottom, filled with liquid scintillator, and have an optical fiber running the entire length of each cell. The fibers terminate at the top of each extrusion in a manifold. An optical-fiber-light-guide connects the fibers in each manifold to a photo-detector. The photo-detector converts the light signals from the scintillator and optical fibers into electrical impulses for computer analysis.

Berg, Timothy John; /Minnesota U.

1997-02-01

76

First photoelectron timing error evaluation of a new scintillation detector model  

SciTech Connect

In this paper, a general timing system model for a scintillation detector developed is experimentally evaluated. The detector consists of a scintillator and a photodetector such as a photomultiplier tube or an avalanche photodiode. The model uses a Poisson point process to characterize the light output from the scintillator. This timing model was used to simulate a BGO scintillator with a Burle 8575 PMT using first photoelectron timing detection. Evaluation of the model consisted of comparing the RMS error from the simulations with the error from the actual detector system. The authors find that the general model compares well with the actual error results for the BGO/8575 PMT detector. In addition, the optimal threshold is found to be dependent upon the energy of the scintillation. In the low energy part of the spectrum, the authors find a low threshold is optimal while for higher energy pulses the optimal threshold increases.

Petrick, N.; Clinthorne, N.H.; Rogers, W.L.; Hero, A.O. III (Michigan Univ., Ann Arbor, MI (United States). Div. of Nuclear Medicine)

1991-04-01

77

Exposure rate by the spectrum dose index method using plastic scintillator detectors.  

PubMed

The spectrum dose index (SDI) method was tested for use with data from plastic scintillator detectors by irradiating a typical portal detector system using different gamma sources and natural background. Measurements were compared with exposure rates simultaneously measured using a calibrated pressurised ion chamber. It was found that a modified SDI algorithm could be used to calculate exposure rates for these detectors despite the lack of photopeaks in plastic scintillator spectra. PMID:21712256

Proctor, Alan; Wellman, Jeffrey

2011-06-28

78

Light collection efficiency and light transport in backscattered electron scintillator detectors in scanning electron microscopy.  

PubMed

Experimentally, scintillator detectors used in scanning electron microscopy (SEM) to record backscattered electrons (BSE) show a noticeable difference in detection efficiency in different parts of their active zones due to light losses transport in the optical part of the detector. A model is proposed that calculates the local efficiency of the active parts of scintillator detectors of arbitrary shapes. The results of these calculations for various designs are presented. PMID:11587323

Filippov, M N; Rau, E I; Sennov, R A; Boyde, A; Howell, P G

79

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

SciTech Connect

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 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.

Bircher, Chad; Shao Yiping [Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)

2012-02-15

80

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

NASA Astrophysics Data System (ADS)

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.

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

81

Operation characteristics of ionizing radiation detectors based on inorganic and plastic scintillators for nuclear physics and medical instrumentation  

Microsoft Academic Search

Main operation characteristics of radiation detectors, using various scintillation substances, are calculated on the base of a realistic optical model of a scintillator. The calculation method takes account of a mirror-type maximum of the diffuse reflection indicatrix which is important for light collection in a scintillator. The comparison is carried out between various cases differing in the scintillator geometry, the

M. Globus; B. Grinyov

1995-01-01

82

Operation characteristics of ionizing radiation detectors based on inorganic and plastic scintillators for nuclear physics and medical instrumentation  

Microsoft Academic Search

Main operation characteristics of radiation detectors, using various scintillation substances, are calculated on the base of a realistic optical model of a scintillator. The calculation method takes account of a mirror-type maximum of the diffuse reflection indicatrix which is important for light collection in a scintillator. The comparison is carried out between various cases. Differing in the scintillator geometry, the

M. Globus; B. Grinyov

1996-01-01

83

Investigations of surface coatings to reduce memory effect in plastic scintillator detectors used for radioxenon detection  

Microsoft Academic Search

In this work Al2O3 and SiO2 coatings are tested as Xe diffusion barriers on plastic scintillator substrates. The motivation is improved beta–gamma coincidence detection systems, used to measure atmospheric radioxenon within the verification regime of the Comprehensive Nuclear-Test-Ban Treaty. One major drawback with the current setup of these systems is that the radioxenon tends to diffuse into the plastic scintillator

L. Bläckberg; A. Fay; I. Jõgi; S. Biegalski; M. Boman; K. Elmgren; T. Fritioff; A. Johansson; L. Mårtensson; F. Nielsen; A. Ringbom; M. Rooth; H. Sjöstrand; M. Klintenberg

2011-01-01

84

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

DOEpatents

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.

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

1987-02-27

85

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

DOEpatents

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.

Chiles, Marion M. (Knoxville, TN); Mihalczo, John T. (Oak Ridge, TN); Blakeman, Edward D. (Oak Ridge, TN)

1989-01-01

86

Gamma-ray imaging detectors based on silicon drift detectors arrays coupled to a single scintillator  

NASA Astrophysics Data System (ADS)

Arrays of Silicon Drift Detectors (SDDs) coupled to a single scintillator, according to the Anger Camera scheme, can be successfully employed in gamma-ray imaging. The low value of output capacitance of a SDD allows to reach a lower electronics noise with respect to conventional silicon photodiodes used in scintillation detection. A small prototype of gamma camera with sub-millimeter resolution has been realized by using a monolithic array of small SDDs (5mm2 each unit) with on-chip JFET. For the realization of gamma cameras of larger areas based on single units assembled in array, SDDs of 30mm2 of area with external JFET have been also experimented.

Fiorini, C.; Longoni, A.

2003-01-01

87

An LSO scintillator array for a PET detector module with depth of interaction measurement  

Microsoft Academic Search

Presents construction methods and performance results for a production scintillator array of 64 optically isolated, 3 mm×3 mm×30 mm sized LSO crystals. This scintillator array has been developed for a PET detector module consisting of the 8×8 LSO array coupled on one end to a single photomultiplier tube (PMT) and on the opposite end to a 64 pixel array of

J. S. Huber; W. W. Moses; M. S. Andreaco; O. Petterson

2001-01-01

88

Detection efficiency loss in a position sensitive scintillator hodoscope neutron detector  

Microsoft Academic Search

A position sensitive detector for 15 MeV neutrons has been built from four NE110 plastic scintillator slabs all together connected to a left and a right photomultiplier. A hodoscope detection system tags each optically isolated scintillating slab, minimizing the transit time spread. Adopting left and right light guides common to the four slabs, a strong decrease of the detection efficiency

A. Pantaleo; L. Fiore; G. Guarino; V. Paticchio; G. D'Erasmo; E. M. Fiore

1989-01-01

89

Development of an industrial computed tomography designed with a plastic scintillator position sensitive detector  

Microsoft Academic Search

An industrial computed tomography (CT) using the plastic scintillator (PS) as a detector sensitive to the radiation interaction position was proposed. Firstly, a code using Monte Carlo method was developed to study the effects of the plastic scintillator geometry in its gamma ray detection. The software simulates the results system designed with two photomultiplier-tubes set up in coincidence. Four simulations

Carlos Henrique de Mesquita; Samuel Legoupil; Margarida Mizue Hamada

2005-01-01

90

Scintillator\\/Photomultiplier Ablation Detector \\/SPAD\\/ for use in reentry vehicles  

Microsoft Academic Search

The Scintillation\\/Photomultiplier Ablation Detector (SPAD), a flight-qualified radiation detector, has been developed for measuring the shape change and ablation characteristics of various reentry vehicle nosetip materials. The removal of many implanted radioactive line sources can be monitored through collimation holes by an equal number of SPADs. The key design features include high gamma ray detection efficiency, small detector cross sectional

W. A. Fitzgerald Jr.; A. W. Mitton Jr.

1977-01-01

91

Neutron/gamma discrimination properties of composite scintillation detectors  

NASA Astrophysics Data System (ADS)

A composite scintillator is a solid solution, which contains the grains of organic molecular single crystal introduced into a polymer matrix and placed inside the housing. Hereunder, we present n/? discrimination properties of four composite scintillators; two of the them are based on p-terphenyl and two others-on stilbene. The results obtained with a stilbene single crystal and a liquid scintillator BC501A are shown as a comparison. Initial conclusion, which is drawn from the paper, is that composite scintillators could be an alternative substitution for commonly used liquid scintillators.

Iwanowska, J.; Swiderski, L.; Moszynski, M.; Szczesniak, T.; Sibczynski, P.; Galunov, N. Z.; Karavaeva, N. L.

2011-07-01

92

Stsintillyatsionnaya triggernaya sistema zhidkoargonovogo nejtrinnogo detektora. (Scintillation trigger system of the liquid argon neutrino detector).  

National Technical Information Service (NTIS)

This paper presents the organization of the Scintillation Trigger System (STS) for the Liquid Argon Neutrino Detector of the Tagged Neutrino Facility. STS is aimed at the effective registration of the needed neutrino interaction type and production of a f...

S. V. Belikov S. N. Gurzhiev Y. Gutnikov A. G. Denisov V. I. Kochetkov

1994-01-01

93

Application of the Amplitude Weighting Method for a Large Scintillation Detector.  

National Technical Information Service (NTIS)

The amplitude weighting method for determining total energy of neutron capture gamma -rays conformably to a large liquid scintillation detector of 4 litres volume is described. On the basis of performed calculations and measurements the accuracy of the de...

V. N. Kononov E. D. Poletaev V. M. Timokhov A. P. Androsenko G. V. Bolonkina

1984-01-01

94

In vivo dosimeters for HDR brachytherapy: A comparison of a diamond detector, MOSFET, TLD, and scintillation detector  

Microsoft Academic Search

The large dose gradients in brachytherapy necessitate a detector with a small active volume for accurate dosimetry. The dosimetric performance of a novel scintillation detector (BrachyFOD{sup TM}) is evaluated and compared to three commercially available detectors, a diamond detector, a MOSFET, and LiF TLDs. An ¹⁹²Ir HDR brachytherapy source is used to measure the depth dependence, angular dependence, and temperature

Jamil Lambert; Tatsuya Nakano; Sue Law; Justin Elsey; David R. McKenzie; Natalka Suchowerska

2007-01-01

95

Testing the Large-area multi-Institutional Scintillator Array (LISA) Neutron Detector  

Microsoft Academic Search

The 144 detector modules comprising the Large-area multi-Institutional Scintillator Array (LISA) neutron detector were tested at each of the nine primarily undergraduate institutions. Each module is a 200 cm by 10 cm by 10 cm bar of EJ-200 organic plastic scintillator a with a photomultiplier tube mounted on each end. We used cosmic rays both to ensure that each module

T. B. Nagi; K. M. Rethman; K. A. Purtell; A. J. Haagsma; C. Deroo; M. Jacobson; S. Kuhn; A. R. Peters; M. Ndong; S. A. Stewart; Z. Torstrick; R. Anthony; H. Chen; A. Howe; N. S. Badger; M. D. Miller; B. J. Foster; L. C. Rice; C. Vest; A. B. Aulie; A. Grovom; L. Elliot; P. Kasavan

2010-01-01

96

Submillimeter resolution in one-dimensional position measurements of ?-ray photons by using a CsI(Tl) scintillator coupled to a linear array of silicon drift detectors  

NASA Astrophysics Data System (ADS)

We present the one-dimensional (1D) position and energy resolution results obtained by a ?-ray detector based on a single CsI(Tl) scintillator coupled to a linear array of silicon drift detectors (SDDs). The present prototype has been realized in order to investigate the basic performances of this new architecture in view of the realization of Anger cameras for 2D imaging in nuclear medicine, based on the use of SDDs instead of photomultiplier tubes. The SDD provides a high value of quantum efficiency to the scintillation light, typical of a silicon photodetector, and is moreover characterized by a lower value of electronics noise with respect to conventional silicon photodiodes, thanks to the low value of output capacitance. At 122 keV the present detector shows a position resolution better than 0.5 mm FWHM, and an energy resolution of about 13% FWHM. The experimental setup is described and the most significant experimental results are presented.

Fiorini, C.; Labanti, C.; Perotti, F.

2000-08-01

97

Monte-Carlo Calculation of the Response Function of the Big Scintillation Detector for Neutron Capture Detection.  

National Technical Information Service (NTIS)

Technique for calculation of the response function of a large liquid scintillation detector of radiation capture events is described. The GAMBAK and CYLIND programs permittinq to calculate gamma -radiation energy losses in the sample and scintillator unde...

P. A. Androsenko G. V. Bolonkina V. N. Kononov E. D. Poletaev V. M. Timokhov

1984-01-01

98

Low dose-rate irradiation set-up for scintillating crystals  

NASA Astrophysics Data System (ADS)

With a 1 Ci 60Co-source we measured the radiation damage and its recovery in PbWO4 crystals. The method consists in measuring the anode current produced in the silicon diode of a Hybrid PhotoMultiplier Tube (HPMT) during the irradiation of the crystal. At regular time intervals, we took photon counting spectra with the same HPMT. By checking the resulting channel positions of the photoelectron peaks, we controlled the stability of our experimental set-up. Temperature control and monitoring were achieved by forced thermostatized water circulation inside the irradiation box and by using a PT100 and two AD590 temperature probes. First results on irradiations of a few PbWO4 crystals are presented and future plans are communicated.

D'Ambrosio, C.; Ercoli, C.; Jaaskelainen, S.; Rosso, E.; Wicht, P.

1997-02-01

99

New scintillating media based on liquid crystals for particle detectors  

Microsoft Academic Search

The study results of optical, photoluminiscent and scintillation properties of a liquid crystal 4-pentyl-4\\/'-cyanobiphenyl are presented. The scintillation light output of this liquid crystal is about 35% of crystal anthracene, its main decay time constants are 4 and 14ns, and the maximum of light emission spectrum is about 400nm. The light output of a dissolution of green emitting light scintillation

M. I. Barnik; S. G. Yudin; V. G. Vasil'chenko; S. V. Golovkin; A. M. Medvedkov; A. S. Solovjev

2000-01-01

100

New scintillating media based on liquid crystals for particle detectors  

Microsoft Academic Search

The study results of optical, photoluminiscent and scintillation properties of a liquid crystal 4-pentyl-4?-cyanobiphenyl are presented. The scintillation light output of this liquid crystal is about 35% of crystal anthracene, its main decay time constants are 4 and 14ns, and the maximum of light emission spectrum is about 400nm. The light output of a dissolution of green emitting light scintillation

M. I. Barnik; S. G. Yudin; V. G. Vasil'chenko; S. V. Golovkin; A. M. Medvedkov; A. S. Solovjev

2000-01-01

101

The gas proportional scintillation counter/microstrip gas chamber hybrid detector  

NASA Astrophysics Data System (ADS)

The gas proportional scintillation counter/microstrip gas chamber (GPSC/MSGC) hybrid detector for X-ray spectrometry is described. The detector uses a CsI-coated microstrip plate placed in direct contact with the gas-filling as the photosensor readout for the GPSC scintillation substituting for the photomultiplier tube (PMT). Usable photosensor maximum gain is limited by optical positive feedback due to the additional scintillation produced in the electron avalanche process at the MSP anodes, in the absence of quenching. A low-photoelectron collection efficiency is achieved in the gas atmosphere, resulting in a scintillation conversion efficiency that is about a factor of 5 lower than that achieved with PMT-based GPSCs. However, energy resolutions of 11% for 5.9keV X-rays are achieved with this detector.

Freitas, D. S. A. P.; Veloso, J. F. C. A.; Monteiro, C. M. B.; Dos Santos, J. M. F.; Conde, C. A. N.

2003-06-01

102

Spatial response characterization of liquid scintillator detectors using collimated gamma-ray and neutron beams  

NASA Astrophysics Data System (ADS)

Liquid scintillators are suitable for many applications because they can detect and characterize fast neutrons as well as gamma-rays. This paper presents the response of a 15-cm-in-length×15-cm-in-height×8.2-cm-in-width EJ-309 liquid scintillator with respect to the position of neutron and gamma-ray interactions. Liquid scintillator cells are typically filled with 97% of the scintillating cocktail to address thermal expansion of the liquid in varying temperature conditions. Measurements were taken with collimated 137Cs and 252Cf sources for gamma-ray and neutron mapping of the detector, respectively. MCNPX-PoliMi (ver. 2.0) simulations were also performed to demonstrate the spatial response of the detector. Results show that the detector response is greatest at the center and decreases when the collimated neutron and gamma-ray beam is moved toward the edge of the detector. The measured response in the voxels surrounding the detector center decreased by approximately 6% and 12% for gamma-ray and neutron scans, respectively, when compared to the center voxel. The measured decrease in the detector response was most pronounced at the corners of detector assembly. For the corner voxels located in the bottom row of the detector, the measured response decreased by approximately 39% for both gamma-ray and neutron scans. For the corner voxels located in the top row of the detector, the measured response decreased by approximately 66% and 48% for gamma-ray and neutron scans, respectively. Both measurements and simulations show the inefficient production of secondary charged particles in the voxels located in the top portion of the detector due to the presence of expansion volume. Furthermore, the presence of the expansion volume potentially affects the transport of the scintillation light through the coupling window between the liquid scintillator and the photocathode in the photomultiplier tube.

Naeem, S. F.; Clarke, S. D.; Pozzi, S. A.

2013-10-01

103

Evaluation of a 2D detector array for patient-specific VMAT QA with different setups  

NASA Astrophysics Data System (ADS)

For pre-treatment plan verification of advanced treatment techniques such as intensity-modulated arc therapy, a fast and reliable dosimetric device is required. In this study, we investigated the suitability of MatriXX in different setups for verification of volumetric modulated arc therapy (VMAT) plans. If MatriXX is used in a stationary phantom (MULTICube), the measured dose is dependent on the beam angle. For the first setup (MatriXX/MULTICube), we developed correction factors (CFs) for each detector element (1020 CFs). We investigated the accuracy of these CFs by verifying 12 VMAT plans. In the second setup, we also assessed the suitability of MatriXX in a dedicated holder. Using this setup (MatriXX/Holder), 30 additional VMAT plans were verified. Deviations of up to ~17% and ~11% were noted for one of the ion chambers at 90° and 180° gantry positions. The influence of the beam angle dependence (MULTICube) can explicitly be seen when a gamma criterion of 2%/2 mm was chosen. An overall improvement of 4.3% of passing pixels (pp) was noted after applying beam angular-dependent CFs. When the gamma criterion was 3%/3 mm, the %pp was >=95% without and ~100% with correction. With the second setup, MatriXX/holder, we showed excellent agreement between measurements and calculations. The %pp averaged over all plans (30 VMAT treatment plans) was nearly ~100%. The combination of MatriXX with MULTICube or with holder proved to be a fast and reliable method for pretreatment verification of arc therapy with sufficient accuracy.

Boggula, Ramesh; Birkner, Mattias; Lohr, Frank; Steil, Volker; Wenz, Frederik; Wertz, Hansjoerg

2011-11-01

104

Modeling and Optimization of Scintillator Arrays for PET Detectors  

Microsoft Academic Search

A new Zemax model has been developed, which reliably predicts the light output of scintillator crystal pins for positron emission tomography. Different configurations, including pin shape, surface finish and reflector types are investigated. The simulations use the actual measured wavelength-dependent parameters of the scintillator crystal, of the reflector and of the PMT's components. Good agreement is demonstrated between simulated and

Gábor Erdei; Imre Péczeli; Cecília Steinbach; Ferenc Ujhelyi; Tamás Bukki

2010-01-01

105

Performance of a scintillating strip detector with G-APD readout  

NASA Astrophysics Data System (ADS)

The upgraded KLM detector end cap of Belle II experiment will consist of more than 16 000 scintillating detectors of 0.5-2.8 m long strips. One of possible solutions is presented: a detector of 2800×40×10 mm3 with light readout via WLS fiber and new solid state photo-detector multi-pixel avalanche photo-diode working in Geiger mode. Concept of the mechanical structure of upgraded KLM detector is given. Properties demonstrating the operation capabilities of such a scintillating detector: MIP registration efficiency, noise pulse rate with respect to expected background rate are demonstrated as well as response distributions in longitudinal and transverse directions. Study of radiation damage of photo-detectors shows that Hamamatsu MPPC can be used in Belle II environment during at least 10 years.

Tarkovsky, Evgueny

2011-02-01

106

Monte Carlo simulation of the nonlinear full peak energy responses for gamma-ray scintillation detectors.  

PubMed

A Monte Carlo code has been developed, which predicts the nonlinear full peak energy responses of scintillation detectors to incident gamma-rays. It is illustrated here for the popular scintillation detectors, NaI and BGO. The full energy response can be determined by treating the detector as effectively infinite and assuming that all photons and electrons are fully absorbed within the detector. This assumption means that no geometrical direction or position tracking is required, only the selection of sequential photon interactions based on the appropriate energy-dependent interaction cross-sections. The full energy pulse-height response is determined by the sum of the pulse-height responses from all secondary electrons. Results from infinite NaI and BGO detectors indicate that even though the maximum difference in electron scintillation efficiency is about the same for the two scintillation detectors, the overall effect on the extent of the difference in pulse height is much less for BGO than NaI. This result is due to the larger density and effective atomic number of BGO, which causes significantly fewer Compton scattering events. Compton scattering interactions reduce the incident photon energy without absorption and therefore give more responses at reduced energy where the electron scintillation efficiency is most different. PMID:22178700

Peeples, Johanna L; Gardner, Robin P

2011-12-08

107

Assessment of a simulation software for scintillation detector  

NASA Astrophysics Data System (ADS)

Aim: A Monte Carlo code based on GEANT 3.21 and Linux platform has been developed and adaptated to simulate gamma detectors dedicated to specific scintigraphic applications. Materials and methods: GEANT 3.21 is freely available at the CERN program library. It has been written for simulating the interactions of particles with energy > 10keV. The energy of the gamma rays used in scintigraphic imaging never exceeds 511keV. Interaction cross-sections for energies between 10keV and 10MeV and three media of interest obtained with this program have been compared with data available on the NIST web site. A gamma peroperative hand-held probe has then been simulated. Sensitivity and spatial resolution were evaluated. Results: The high standard deviation for total attenuation coefficient is 4.7% with an uncertainty around 4% given by NIST. The good results obtained have allowed us to go farther in computer programming. In the hope of integrating all the detection lines new routines have been introduced for the simulation of scintillation photons and optical effects. First simulated optical spots have a diameter of 2.5mm (FWHM) for a 6mm NaI(Tl) thickness and gamma rays of 140keV. Conclusion: The code was recently improved with the implementation of a photomultiplier tube and the algorithm for the image reconstruction. In this way, the computed image can be compared with optical image obtained just before the photocathode to improve algorithm. Soon, simulation results will be tested with a mini gamma-camera prototype.

Crespin, S.; de Freitas, D.; Brette, P.; Falvard, A.; Maublant, J.

2004-07-01

108

Plastic scintillator-based radiation detector for mobile radiation detection system against nuclear\\/radiological terrorism  

Microsoft Academic Search

Illicit trafficking of nuclear or radioactive materials has become a serious world wide problem. Due to operational constraints of radiation detection system for such nuclear security application, a radiation detector with large effective area is needed to maximize its sensitivity. This paper suggests a new method of using plastic scintillation detector as a cost-effective mobile radiation detection system. Monte Carlo

Sung-Woo Kwak; Ho-Sik Yoo; Sung Soon Jang; Jung Soo Kim; Wan-Ki Yoon; In Sub Jun; Kwang Hyun Kim

2009-01-01

109

Stabilizing scintillation detector systems by exploiting the temperature dependence of the light pulse decay time  

Microsoft Academic Search

Scintillation detectors must tolerate a wide range of ambient temperatures and strong temperature slopes when used in outdoor applications. Such demanding conditions are typical for all homeland security applications. An effective and efficient detector stabilization compensating for temperature dependent gain shifts is essential to maintain energy calibration and resolution. Reliable, well-established solutions are based on radioactive reference sources; however, alternatives

Guntram Pausch; J. Stein; N. Teofilov

2005-01-01

110

Design and Testing of a Position-Sensitive Plastic Scintillator Detector for Fast Neutron Imaging  

Microsoft Academic Search

We describe the design and performance of a position sensitive scintillator detector developed for neutron measurements. Several of these detectors are to be used in the assembly of the Fast Neutron Imaging Telescope (FNIT), an instrument with imaging and energy measurement capabilities, sensitive to neutrons in the 2-20 MeV energy range. FNIT was initially conceived to study solar neutrons as

Ulisse Bravar; Paul J. Bruillard; Erwin O. Flückiger; John R. Macri; Mark L. McConnell; Michael R. Moser; James M. Ryan; Richard S. Woolf

2006-01-01

111

Gamma-ray imaging detectors based on SDDs coupled to scintillators  

NASA Astrophysics Data System (ADS)

Silicon Drift Detectors (SDDs) have been recently employed succesfully in scintillation detection. Owing to the low value of output capacitance, a SDD is in fact characterized by a lower electronics noise with respect to a conventional silicon photodiode. This feature could allow a detector based on a CsI(Tl)-SDD assembly to reach high energy and position resolution in gamma detection. In this work, we present a small prototype of gamma detector for 2-D position measurements, based on a single scintillator coupled to an array of SDDs. The first experimental results are reported.

Fiorini, C.; Longoni, A.; Perotti, F.; Labanti, C.; Rossi, E.; Lechner, P.; Strüder, L.

2001-04-01

112

An analytic technique for the estimation of the light yield of a scintillation detector.  

NASA Astrophysics Data System (ADS)

A simple model for the estimation of the light yield of a scintillation detector is developed under general assumptions and relying exclusively on the knowledge of its optical properties. The model allows one to easily incorporate effects related to Rayleigh scattering and absorption of the photons. The predictions of the model are benchmarked with the outcomes of Monte Carlo simulations of specific scintillation detectors. An accuracy at the level of few percent is achieved. The case of a real liquid argon based detector is explicitly treated and the predicted light yield is compared with the measured value.

Segreto, E.

2013-10-01

113

Optical simulation of monolithic scintillator detectors using GATE/GEANT4  

NASA Astrophysics Data System (ADS)

Much research is being conducted on position-sensitive scintillation detectors for medical imaging, particularly for emission tomography. Monte Carlo simulations play an essential role in many of these research activities. As the scintillation process, the transport of scintillation photons through the crystal(s), and the conversion of these photons into electronic signals each have a major influence on the detector performance; all of these processes may need to be incorporated in the model to obtain accurate results. In this work the optical and scintillation models of the GEANT4 simulation toolkit are validated by comparing simulations and measurements on monolithic scintillator detectors for high-resolution positron emission tomography (PET). We have furthermore made the GEANT4 optical models available within the user-friendly GATE simulation platform (as of version 3.0). It is shown how the necessary optical input parameters can be determined with sufficient accuracy. The results show that the optical physics models of GATE/GEANT4 enable accurate prediction of the spatial and energy resolution of monolithic scintillator PET detectors.

(Jan van der Laan, D. J.; Schaart, Dennis R.; Maas, Marnix C.; Beekman, Freek J.; Bruyndonckx, Peter; van Eijk, Carel W. E.

2010-03-01

114

A sensitivity analysis approach to optical parameters of scintillation detectors  

Microsoft Academic Search

In this study, an extended version of the Monte Carlo light transport code, PHOTRACK, has been used for a sensitivity analysis to estimate the importance of different wavelength-dependent parameters in the modelling of light collection process in scintillators.

N. Ghaleh; R. Koohifayegh

2008-01-01

115

Development of a small scintillation detector with an optical fiber for fast neutrons.  

PubMed

To investigate the characteristics of a reactor and a neutron generator, a small scintillation detector with an optical fiber with ThO(2) has been developed to measure fast neutrons. However, experimental facilities where (232)Th can be used are limited by regulations, and S/N ratio is low because the background counts of this detector are increase by alpha decay of (232)Th. The purpose of this study is to develop a new optical fiber detector for measuring fast neutrons that does not use nuclear material such as (232)Th. From the measured and calculated results, the new optical fiber detector which uses ZnS(Ag) as a converter material together with a scintillator have the highest detection efficiency among several developed detectors. It is applied for the measurement of reaction rates generated from fast neutrons; furthermore, the absolute detection efficiency of this detector was obtained experimentally. PMID:21129989

Yagi, T; Unesaki, H; Misawa, T; Pyeon, C H; Shiroya, S; Matsumoto, T; Harano, H

2010-11-25

116

Construction and test of an X-ray CT setup for material resolved 3D imaging with Medipix based detectors  

NASA Astrophysics Data System (ADS)

A prototype computerized tomography (CT) setup has been recently built at Nikhef in order to exploit the material resolved capabilities of Medipix based detectors in X-ray imaging. The CT scanner contains a Hamamatsu 90 kVp microfocus X-ray tube and an entirely remotely controllable sample alignment system. The complete setup is fully integrated with the detector operation software. Moreover the 120 frames/s RelaxD readout system [1] allows real time X-ray imaging of fast moving samples. In this work, the description of the setup is given and the first results obtained with Medipix2 [2] and Timepix [3] detectors are presented. They concern detector calibration with fluorescence lines, CT reconstruction of small biological and non-biological samples and material resolved 3D micro-imaging [4].

Schioppa, Enrico, Jr.; Uher, Josef; Visser, Jan

2012-10-01

117

Cerium doped GSO scintillators and its application to position sensitive detectors  

Microsoft Academic Search

The dependence of the light output and the decay times of Ce doped GdâSiOâ on Ce concentration is measured. By using the difference in decay times on Ce concentration for GSO(Ce), the combination of different concentration of GSO(Ce) scintillators is shown to be useful as position sensitive detectors. A Ce doped GdâSiOâ (GSO(Ce)) single crystal is an excellent scintillator featuring,

H. Ishibashi; K. Shimizu; K. Susa; S. Kubota

1989-01-01

118

Temperature dependence of spurious pulses in use of plastic scintillation detectors  

Microsoft Academic Search

Pulse-height and time spectra of afterpulses from a scintillation detector with NE102A scintillator sandwiching a 60Co source were observed at several different temperatures. From time analysis with a slow amplifier followed by a conventional TAC, spurious pulses are grouped into two types; time-dependent afterpulses and random noise. The intensity of afterpulses decreased considerably with increasing temperature, while the intensity of

Yasushi Kawada; Jun Ito; Qiu-Wei Wang

2004-01-01

119

Coincidence system for standardization of radionuclides using a 4? plastic scintillator detector  

Microsoft Academic Search

A coincidence system using a plastic scintillator detector in 4? geometry has been developed and applied for the standardization of radionuclides. The scintillator shape and dimensions have been optimized for maximum charge particle detection efficiency, while keeping background low and a nearly constant gamma-ray efficiency for different points from the radioactive source. The gamma-ray events were measured with a NaI(Tl)

A??da M. Baccarelli; Mauro S. Dias; Marina F. Koskinas

2003-01-01

120

PHOTON An optical Monte Carlo code for simulating scintillation detector responses  

NASA Astrophysics Data System (ADS)

A Monte Carlo code, PHOTON, has been developed to simulate optical photon transport in scintillation detectors. The code supports arbitrarily complex geometry models, flexible models for material and surface properties specification, detailed treatment of complex refractive index materials, thin-film surface coatings and interactive simulation with graphical display. This paper concentrates on the photon transport simulation and a simple benchmarking study, comparing the experimental and calculated light yields from a rectangular plastic scintillator block.

Tickner, James; Roach, Greg

2007-10-01

121

Basic performance of a large area PET detector with a monolithic scintillator  

Microsoft Academic Search

Conventionally, block detectors, which consist of a two-dimensionally segmented scintillator array with inserted reflectors,\\u000a are often used for PET. On the other hand, PET detectors with a monolithic block have been investigated because they are expected\\u000a to offer higher resolution than do segmented crystal arrays. However, previous reports focused on detectors dedicated as small-animal\\u000a PET, and the thickness was not

Eiji Yoshida; Naoko Inadama; Hiroto Osada; Hideyuki Kawai; Fumihiko Nishikido; Hideo Murayama; Tomoaki Tsuda; Taiga Yamaya

122

Combinatorial Screening of Advanced Scintillators for High Resolution X-ray Detectors  

SciTech Connect

The lack of efficient scintillators is a major problem for developing powerful x-ray detectors that are widely used in homeland security, industrial and scientific research. Intematix has developed and applied a high throughput screening process and corresponding crystal growth technology to significantly speed up the discovery process for new efficient scintillators. As a result, Intematix has invented and fabricated three new scintillators both in powder and bulk forms, which possess promising properties such as better radiation hardness and better matching for silicon diode.

Cheng, Shifan; Tao, Dejie; Lynch, Michael; Yuan, Xianglong; Li, Yiqun

2008-05-12

123

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

PubMed

To measure the intensity of flash X-ray sources directly, a novel scintillation detector with a fast time response and flat energy response is developed by combining film scintillators of doped ZnO crystal and fast organic scintillator together. Through compensation design, the dual-scintillator detector (DSD) achieved a flat energy response to X-rays from tens of keV to several MeV, and sub-nanosecond time response by coupling to ultrafast photo-electronic devices. A prototype detector was fabricated according to the theoretical design; it employed ZnO:In and EJ228 with thicknesses of 0.3 mm and 0.1 mm, respectively. The energy response of this detector was tested on monoenergetic X-ray and ?-ray sources. The detector performs very well with a sensitivity fluctuation below 5% for 8 discrete energy points within the 40-250 keV energy region and for other energies of 662 keV and 1.25 MeV as well, showing good accordance with the theoretical design. Additionally, the detector works properly for the application to the flash X-ray radiation field absolute intensity measurement. This DSD may be very useful for the diagnosis of time-resolved dynamic physical processes of flash X-ray sources without knowing the exact energy spectrum. PMID:23387633

Chen, Liang; Ouyang, Xiaoping; Liu, Bin; Liu, Jinliang; Quan, Lin; Zhang, Zhongbing

2013-01-01

124

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

NASA Astrophysics Data System (ADS)

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

Chen, Liang; Ouyang, Xiaoping; Liu, Bin; Liu, Jinliang; Quan, Lin; Zhang, Zhongbing

2013-01-01

125

Assessment of the setup dependence of detector response functions for mega-voltage linear accelerators  

SciTech Connect

Purpose: Accurate modeling of beam profiles is important for precise treatment planning dosimetry. Calculated beam profiles need to precisely replicate profiles measured during machine commissioning. Finite detector size introduces perturbations into the measured profiles, which, in turn, impact the resulting modeled profiles. The authors investigate a method for extracting the unperturbed beam profiles from those measured during linear accelerator commissioning. Methods: In-plane and cross-plane data were collected for an Elekta Synergy linac at 6 MV using ionization chambers of volume 0.01, 0.04, 0.13, and 0.65 cm{sup 3} and a diode of surface area 0.64 mm{sup 2}. The detectors were orientated with the stem perpendicular to the beam and pointing away from the gantry. Profiles were measured for a 10x10 cm{sup 2} field at depths ranging from 0.8 to 25.0 cm and SSDs from 90 to 110 cm. Shaping parameters of a Gaussian response function were obtained relative to the Edge detector. The Gaussian function was deconvolved from the measured ionization chamber data. The Edge detector profile was taken as an approximation to the true profile, to which deconvolved data were compared. Data were also collected with CC13 and Edge detectors for additional fields and energies on an Elekta Synergy, Varian Trilogy, and Siemens Oncor linear accelerator and response functions obtained. Response functions were compared as a function of depth, SSD, and detector scan direction. Variations in the shaping parameter were introduced and the effect on the resulting deconvolution profiles assessed. Results: Up to 10% setup dependence in the Gaussian shaping parameter occurred, for each detector for a particular plane. This translated to less than a {+-}0.7 mm variation in the 80%-20% penumbral width. For large volume ionization chambers such as the FC65 Farmer type, where the cavity length to diameter ratio is far from 1, the scan direction produced up to a 40% difference in the shaping parameter between in-plane and cross-plane measurements. This is primarily due to the directional difference in penumbral width measured by the FC65 chamber, which can more than double in profiles obtained with the detector stem parallel compared to perpendicular to the scan direction. For the more symmetric CC13 chamber the variation was only 3% between in-plane and cross-plane measurements. Conclusions: The authors have shown that the detector response varies with detector type, depth, SSD, and detector scan direction. In-plane vs cross-plane scanning can require calculation of a direction dependent response function. The effect of a 10% overall variation in the response function, for an ionization chamber, translates to a small deviation in the penumbra from that of the Edge detector measured profile when deconvolved. Due to the uncertainties introduced by deconvolution the Edge detector would be preferable in obtaining an approximation of the true profile, particularly for field sizes where the energy dependence of the diode can be neglected. However, an averaged response function could be utilized to provide a good approximation of the true profile for large ionization chambers and for larger fields for which diode detectors are not recommended.

Fox, Christopher; Simon, Tom; Simon, Bill; Dempsey, James F.; Kahler, Darren; Palta, Jatinder R.; Liu Chihray; Yan Guanghua [Sun Nuclear Inc., 425-A Pineda Court, Melbourne, Florida 32940 and Department of Radiation Oncology, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States); NRE, 202 Nuclear Science Building, University of Florida, P.O. Box 118300, Gainesville, Florida 32611-8300 and Sun Nuclear Inc., 425-A Pineda Court, Melbourne, Florida 32940 (United States); Sun Nuclear Inc., 425-A Pineda Court, Melbourne, Florida 32940 (United States); ViewRay Inc., 2 Thermo Fisher Way, Oakwood Village, Ohio 44146 (United States); Department of Radiation Oncology, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States)

2010-02-15

126

An X-ray imaging pixel detector based on scintillator filled pores in a silicon matrix  

NASA Astrophysics Data System (ADS)

An X-ray imaging pixel detector has been fabricated and preliminary testing has demonstrated a proof-of-principle. The detector is based on a conventional charge coupled detector (CCD)-imaging detector where a scintillator-filled silicon pore matrix provides enhanced X-ray sensitivity without sacrificing lateral resolution. The scintillator blocks inside the pores provide light guiding of the emitted visible photons to increase the number of photons detected by the CCD element. Preliminary X-ray measurements demonstrate good lateral resolution although non-uniform filling of the pore matrix results in a pronounced fixed noise pattern. The detector has primary applications in dental imaging but would also be of importance in other imaging techniques where the X-ray absorption length exceeds lateral pixel size.

Kleimann, P.; Linnros, J.; Fröjdh, C.; Petersson, C. S.

2001-03-01

127

A Novel Particle Detector: Quantum Dot Doped Liquid Scintillator  

NASA Astrophysics Data System (ADS)

Quantum dots are semiconducting nanocrystals. When excited by light shorter then their characteristic wavelength, they re-emit in a narrow band around this wavelength. The size of the quantum is proportional to the characteristic wavelength so they can be tuned for many applications. CdS quantum dots are made in wavelengths from 360nm to 460nm, a perfect range for the sensitivity of photo-multiplier tubes. The synthesis of quantum dots automatically leaves them in toluene, a good organic scintillator and Cd is a particularly interesting material as it has one of the highest thermal neutron cross sections and has several neutrinoless double beta decay and double electron capture isotopes. The performance of quantum dot loaded scintillator compared to standard scintillators is measured and some unique properties presented. )

Winslow, Lindley; Conrad, Janet; Jerry, Ruel

2010-02-01

128

Water-equivalent plastic scintillation detectors for high-energy beam dosimetry: I. Physical characteristics and theoretical considerations  

Microsoft Academic Search

A minimally perturbing plastic scintillation detector has been developed for the dosimetry of high-energy beams in radiotherapy. The detector system consists of two identical parallel sets of radiation-resistant optical fibre bundles, each connected to independent photomultiplier tubes (PMT). One fibre bundle is connected to a miniature water-equivalent plastic scintillator and so scintillation as well as Cerenkov light generated in the

A. S. Beddar; T. R. Mackie; F. H. Attix

1992-01-01

129

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

SciTech Connect

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

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

2009-01-01

130

A Measurement of the Scintillation Light Yield in CD4 Using a Photosensitive GEM Detector  

SciTech Connect

The absolute photon yield of scintillation light produced by highly ionizing particles in pure CF{sub 4} has been measured using a photosensitive Gas Electron Multiplier (GEM) detector. The detector consists of two standard GEMs and a CsI coated GEM which acts as a photocathode that is sensitive to the 160 nm scintillation light produced in CF{sub 4}. The light yield was determined in terms of the number of scintillation photons emitted into a 4{pi} solid angle produced per MeV of energy deposited in the gas by a 5.5 MeV alpha particle and found to be 314 {+-} 15 photons per MeV. The quantum yield was determined using a fitting method to determine the number of photoelectrons from the measured pulse height distribution, and by an independent method using the measured gain of the GEM detector. The effect of scintillation light in CF{sub 4} on the performance of Cherenkov detectors, such as the PHENIX Hadron Blind Detector (HBD) at RHIC, is also discussed.

Azmoun, B.; Azmoun, B.; Caccavano, A.; Rumore, M.; Sinsheimer, J.; Smirnov, N.; Stoll, S.; Woody, C.

2010-08-01

131

Quantum noise in digital x-ray image detectors with optically coupled scintillators  

SciTech Connect

Digital x-ray imaging detectors designed to soft x-ray (1 to 50 keV) are significant for medical mammography, dental radiography, microradiography, and microtomography. Detector designs involve either direct absorption of x-rays in solid state devices or thin scintillator screens optically coupled to solid state sensors. Well designed scintillator systems produce 10 or more electrons per detected x-ray and, used with charge coupled devices (CCD), detect 100,000 x-rays per pixel before saturation. However, if the scintillator is directly coupled to the detector, radiation can penetrate to the semiconductor detector with a small number of events producing large charge and noise. The authors have investigated the degradation of image noise by these direct absorption events using numerical models for a laboratory detector system consisting of a 60 {micro}m CsI scintillator optically coupled to a scientific CCD. Monte Carlo methods were used to estimate the charge deposition signal and noise for both the CsI and the semiconductor. Without a fiber optic coupler, direct absorptions dominate the signal and increase the signal variance by a factor of about 30 at energies above 10 keV. With a 3 mm fiber optic coupler, no significant degradation is observed for input energies below 45 keV.

Flynn, M.J.; Hames, S.M. [Henry Ford Health System, Detroit, MI (United States)]|[Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering; Wilderman, S.J. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering; Ciarelli, J.J. [Henry Ford Health System, Detroit, MI (United States)

1996-08-01

132

Deep VUV Scintillators for Detectors Working in Cryogenic Environment  

Microsoft Academic Search

The properties of various inorganic scintillator materials with different origin of their VUV luminescence have been studied under pulsed excitation by XUV (50-1000 eV) synchrotron radiation. A comparison of spectral and timing characteristics of these crystalline VUV emitters has been performed. The processes of energy transfer from the host crystal to the luminescence centers of different nature were analyzed from

Vladimir Babin; Eduard Feldbach; Marco Kirm; Vladimir N. Makhov; Sebastian Vielhauer

2008-01-01

133

Optimization of the scintillation detector in a combined 3D megavoltage CT scanner and portal imager.  

PubMed

A parametric study is described leading to the optimization of a custom-made scintillation detector with a relatively high quantum efficiency (QE) for megavoltage photons and light output toward a remote lens. This detector allows low-dose portal imaging and continuous cone-beam megavoltage CT acquisition. The EGS4 Monte Carlo code was used to simulate the x-ray and electron transport in the detector. A Monte Carlo model of optical photon transport in a detector element was devised and used as well as various irradiation experiments on scintillators. Different detector materials and configurations were compared in terms of the optical photon irradiance on the lens from on- and off-axis detector elements and the practical constraints regarding detector construction and weight. Effects of scintillator material, detector element size, crystal coating type, and reflectivity, combinations of different coatings on detector faces, scintillator doping level, and crystal transparency were studied. With scintillator thickness adjusted to give an 18% x-ray QE at 6 MV, the light output of CsI(Tl) was at least eight times higher than ZnWO4, BGO and NE118 plastic. Further, CsI(Tl) showed the smallest decrease in QE going from 6 to 24 MV. The off-axis reduction in emittance from the periphery of the detector was relatively small with a slight dependence on the type and reflectivity of the coating and the crystal thickness for a fixed detector element cross section. Light output was more strongly dependent on the reflectivity of lambertian coatings than specular ones. For a fixed detector element cross section, optimum coating type depended on crystal thickness. Typical CsI(Tl) crystals showed a relatively small variation in light output with changes in optical attenuation length. The optimum detector element was found to be CsI(Tl) coated on five faces with TiO2-loaded epoxy resin offering about a ten-fold improvement in light output per incident photon compared to typical metal/phosphor screens. PMID:9800695

Mosleh-Shirazi, M A; Swindell, W; Evans, P M

1998-10-01

134

In vivo dosimeters for HDR brachytherapy: a comparison of a diamond detector, MOSFET, TLD, and scintillation detector.  

PubMed

The large dose gradients in brachytherapy necessitate a detector with a small active volume for accurate dosimetry. The dosimetric performance of a novel scintillation detector (BrachyFOD) is evaluated and compared to three commercially available detectors, a diamond detector, a MOSFET, and LiF TLDs. An 192Ir HDR brachytherapy source is used to measure the depth dependence, angular dependence, and temperature dependence of the detectors. Of the commercially available detectors, the diamond detector was found to be the most accurate, but has a large physical size. The TLDs cannot provide real time readings and have depth dependent sensitivity. The MOSFET used in this study was accurate to within 5% for distances of 20 to 50 mm from the 192Ir source in water but gave errors of 30%-40% for distances greater than 50 mm from the source. The BrachyFOD was found to be accurate to within 3% for distances of 10 to 100 mm from an HDR 192Ir brachytherapy source in water. It has an angular dependence of less than 2% and the background signal created by Cerenkov radiation and fluorescence of the plastic optical fiber is insignificant compared to the signal generated in the scintillator. Of the four detectors compared in this study the BrachyFOD has the most favorable combination of characteristics for dosimetry in HDR brachytherapy. PMID:17555257

Lambert, Jamil; Nakano, Tatsuya; Law, Sue; Elsey, Justin; McKenzie, David R; Suchowerska, Natalka

2007-05-01

135

In vivo dosimeters for HDR brachytherapy: A comparison of a diamond detector, MOSFET, TLD, and scintillation detector  

SciTech Connect

The large dose gradients in brachytherapy necessitate a detector with a small active volume for accurate dosimetry. The dosimetric performance of a novel scintillation detector (BrachyFOD{sup TM}) is evaluated and compared to three commercially available detectors, a diamond detector, a MOSFET, and LiF TLDs. An {sup 192}Ir HDR brachytherapy source is used to measure the depth dependence, angular dependence, and temperature dependence of the detectors. Of the commercially available detectors, the diamond detector was found to be the most accurate, but has a large physical size. The TLDs cannot provide real time readings and have depth dependent sensitivity. The MOSFET used in this study was accurate to within 5% for distances of 20 to 50 mm from the {sup 192}Ir source in water but gave errors of 30%-40% for distances greater than 50 mm from the source. The BrachyFOD{sup TM} was found to be accurate to within 3% for distances of 10 to 100 mm from an HDR {sup 192}Ir brachytherapy source in water. It has an angular dependence of less than 2% and the background signal created by Cerenkov radiation and fluorescence of the plastic optical fiber is insignificant compared to the signal generated in the scintillator. Of the four detectors compared in this study the BrachyFOD{sup TM} has the most favorable combination of characteristics for dosimetry in HDR brachytherapy.

Lambert, Jamil; Nakano, Tatsuya; Law, Sue; Elsey, Justin; McKenzie, David R.; Suchowerska, Natalka [School of Physics, University of Sydney, NSW 2006 (Australia) and Department of Radiation Oncology, Royal Prince Alfred Hospital, Camperdown, NSW 2050 (Australia); School of Physics, University of Sydney, NSW 2006 (Australia); School of Physics, University of Sydney, NSW 2006 (Australia) and Optical Fibre Technology Centre, Australian Technology Park, Eveleigh, NSW 2015 (Australia); Bandwidth Foundry Pty Ltd, Suite 102 National Innovation Centre, Australian Technology Park, NSW 1430 (Australia); School of Physics, University of Sydney, NSW 2006 (Australia); School of Physics, University of Sydney, NSW 2006 Australia and Department of Radiation Oncology, Royal Prince Alfred Hospital, Camperdown, NSW 2050 (Australia)

2007-05-15

136

Scintillator-Lucite sandwich detector for /n/? separation in the GeV energy region  

NASA Astrophysics Data System (ADS)

A Scintillator-Lucite Sandwich Detector (SLSD) has been developed for /n/? separation in the GeV energy region. An efficient /n/? separation is achieved by measuring a correlation between the scintillation and Cherenkov light yields. The basic performance of the detector has been tested with e, /? and p beams with momenta between 0.5 and 2.0GeV/c; the results were compared with a Monte-Carlo simulation. The /n/? separation capability of this detector has been studied by simulations in the energy range from 5MeV to 12GeV. The SLSD detector was successfully used for a beam survey of the new KL0 beam line built for a KL0-->?0??¯ experiment at the KEK 12-GeV proton synchrotron.

Watanabe, H.; Abe, K.; Harada, E.; Inoue, S.; Inagaki, T.; Kobayashi, S.; Kurilin, A. S.; Lim, G. Y.; Ogawa, I.; Okuno, H.; Omata, K.; Sato, T.; Shinkawa, T.; Tsamalaidze, Z.; Tsukamoto, T.; Yoshimura, Y.

2002-05-01

137

Gamma-ray detector employing scintillators coupled to semiconductor drift photodetectors  

DOEpatents

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 to substantially maximize the ratio of the signal to the electronic noise.

Iwanczyk, Jan S. (Los Angeles, CA); Patt, Bradley E. (Sherman Oaks, CA)

2003-01-01

138

Evaluation of large volume SrI2(Eu) scintillator detectors  

Microsoft Academic Search

There is an ever increasing demand for gamma-ray detectors which can achieve good energy resolution, high detection efficiency, and room-temperature operation. We are working to address each of these requirements through the development of large volume SrI2(Eu) scintillator detectors. In this work, we have evaluated a variety of SrI2 crystals with volumes >10 cm3. The goal of this research was

Benjamin W. Sturm; Nerine J. Cherepy; Owen B. Drury; Peter A. Thelin; Scott E. Fisher; Albert F. Magyar; Stephen A. Payne; Arnold Burger; Lynn A. Boatner; Joanne O. Ramey; Kanai S. Shah; Rastgo Hawrami

2010-01-01

139

Development of a new neutron monitor using a boron-loaded organic liquid scintillation detector  

Microsoft Academic Search

A new type of neutron dose monitor was developed by using a 12.7cm diameter×12.7cm long boron-loaded organic liquid scintillation detector BC523A. This detector aims to have a response in the wide energy range of thermal energy to 100MeV by using the H and C reactions to the fast neutrons of organic liquid and the 10B(n,?) reaction to thermalized neutrons in

A. H. D Rasolonjatovo; T. Shiomi; E. Kim; T. Nakamura; T. Nunomiya; A. Endo; Y. Yamaguchi; M. Yoshizawa

2002-01-01

140

Toward a Real-Time In Vivo Dosimetry System Using Plastic Scintillation Detectors  

Microsoft Academic Search

Purpose: In the present study, we have presented and validated a plastic scintillation detector (PSD) system designed for real-time multiprobe in vivo measurements. Methods and Materials: The PSDs were built with a dose-sensitive volume of 0.4 mm³. The PSDs were assembled into modular detector patches, each containing five closely packed PSDs. Continuous dose readings were performed every 150 ms, with

Louis Archambault; Tina M. Briere; Falk Poenisch; Luc Beaulieu; Deborah A. Kuban; Andrew Lee; Sam Beddar

2010-01-01

141

Development of the Fast Scintillation Detector with Programmable High Voltage Adjustment Suitable for Mössbauer Spectroscopy  

Microsoft Academic Search

This work is focused on a development of a compact fast scintillation detector suitable for Mössbauer spectroscopy (low energy X-ray\\/gamma-ray detection) where high counting rates are inevitable. Optimization of this part was necessary for a reliable function, better time resolution and to avoid a detector pulses pile-up effect. The pile-up effect decreases the measurement performance, significantly depends on the source

R. Prochazka; J. Pechousek; J. Frydrych

2010-01-01

142

SNM detection by means of thermal neutron interrogation and a liquid scintillation detector  

NASA Astrophysics Data System (ADS)

The feasibility of using a pulsed neutron generator in a graphite assembly together with a single liquid scintillation detector for the detection of special nuclear materials is investigated. Thermal source neutrons induce fission in fissile material present in the sample. By means of pulse shape discrimination the detector signals from fast fission neutrons are easily identified among the signals from gamma rays and the interrogating thermal neutrons. The method has potential in applications for detection of special nuclear materials in shielded containers.

Ocherashvili, A.; Roesgen, E.; Beck, A.; Caspi, E. N.; Mosconi, M.; Crochemore, J.-M.; Pedersen, B.

2012-03-01

143

First Results of a Scintillating GEM Detector for 2-D Dosimetry in an Alpha Beam  

Microsoft Academic Search

The characterization of a scintillating GEM based gas detector for quality control of clinical radio-therapeutic beams is presented. Photons emitted by the Ar\\/CF4 gas mixture are detected by means of a CCD camera; in addition, the charge is measured. The detector response has been studied as a function of alpha particle energy and dose rate. The measured signal underestimation, at

Enrica Seravalli; Jeffrey Hendrikse; Jan Huizenga; Rob Kreuger; J. Marco Schippers; Andrea Simon; Carel W. E. van Eijk

2007-01-01

144

PHOTON – An optical Monte Carlo code for simulating scintillation detector responses  

Microsoft Academic Search

A Monte Carlo code, PHOTON, has been developed to simulate optical photon transport in scintillation detectors. The code supports arbitrarily complex geometry models, flexible models for material and surface properties specification, detailed treatment of complex refractive index materials, thin-film surface coatings and interactive simulation with graphical display. This paper concentrates on the photon transport simulation and a simple benchmarking study,

James Tickner; Greg Roach

2007-01-01

145

Simulations of Lateral Distributions of a Signal Produced in Scintillation Detectors by Giant Air Showers  

Microsoft Academic Search

The lateral distributions of a signal, a response of scintillation detectors, have been simulated for vertical giant air showers in terms of the quark-gluon string model. Simulations have been carried out with the help of the suggested 5-level scheme. The estimated lateral structure function is more steep than the standard function used at the Yakutsk array to interpret data. At

L. G. Dedenko; G. F. Fedorova; E. Yu. Fedunina; T. M. Roganova; A. V. Glushkov; D. V. Skobeltsin

146

Development of a thermal neutron detector based on scintillating fibers and silicon photomultipliers  

SciTech Connect

We propose a technique for thermal neutron detection, based on a {sup 6}Li converter placed in front of scintillating fibers readout by means of silicon photomultipliers. Such a technique allows building cheap and compact detectors and dosimeters, thus possibly opening new perspectives in terms of granular monitoring of neutron fluxes as well as space-resolved neutron detection.

Barbagallo, Massimo; Greco, Giuseppe; Scire, Carlotta; Scire, Sergio [INFN Laboratori Nazionali del Sud, via S. Sofia 62, 95125 Catania (Italy); Ansaldo Nucleare S.p.A., corso Perrone 25, 16161 Genova (Italy); Cosentino, Luigi; Pappalardo, Alfio; Finocchiaro, Paolo [INFN Laboratori Nazionali del Sud, via S. Sofia 62, 95125 Catania (Italy); Montereali, Rosa Maria; Vincenti, Maria Aurora [ENEA C.R. Frascati, Via Enrico Fermi, 45, 00044 Frascati, Roma (Italy)

2010-09-15

147

Limits on low-energy neutrino fluxes with the Mont Blanc liquid scintillator detector  

Microsoft Academic Search

The LSD liquid scintillation detector has been operating since 1985 as an underground neutrino observatory in the Mont Blanc Laboratory with the main objective of detecting antineutrino bursts from collapsing stars. In August 1988 the construction of an additional lead and borex paraffin shield considerably reduced the radioactive background and increased the sensitivity of the apparatus. In this way the

M. Aglietta; P. Antonioli; G. Badino; G. Bologna; C. Castagnoli; A. Castellina; V. L. Dadykin; W. Fulgione; P. Galeotti; F. F. Khalchukov; E. V. Korolkova; P. V. Kortchaguin; V. B. Kortchaguin; V. A. Kudryavtsev; A. S. Malguin; L. Periale; V. G. Ryassny; O. G. Ryazhskaya; O. Saavedra; G. Trinchero; S. Vernetto; V. F. Yakushev; G. T. Zatsepin

1992-01-01

148

Wavelength-Shifting-Fiber Scintillation Detectors for Thermal Neutron Imaging at SNS  

SciTech Connect

We have developed wavelength-Shifting-fiber Scintillator Detector (SSD) with 0.3 m2 area per module. Each module has 154 x 7 pixels and a 5 mm x 50 mm pixel size. Our goal is to design a large area neutron detector offering higher detection efficiency and higher count-rate capability for Time-Of-Flight (TOF) neutron diffraction in Spallation Neutron Source (SNS). A ZnS/6LiF scintillator combined with a novel fiber encoding scheme was used to record the neutron events. A channel read-out-card (CROC) based digital-signal processing electronics and position-determination algorithm was applied for neutron imaging. Neutron-gamma discrimination was carried out using pulse-shape discrimination (PSD). A sandwich flat-scintillator detector can have detection efficiency close to He-3 tubes (about 10 atm). A single layer flat-scintillator detector has count rate capability of 6,500 cps/cm2, which is acceptable for powder diffractometers at SNS.

Clonts, Lloyd G [ORNL; Cooper, Ronald G [ORNL; Crow, Lowell [ORNL; Diawara, Yacouba [ORNL; Ellis, E Darren [ORNL; Funk, Loren L [ORNL; Hannan, Bruce W [ORNL; Hodges, Jason P [ORNL; Richards, John D [ORNL; Riedel, Richard A [ORNL; Wang, Cai-Lin [ORNL

2012-01-01

149

A scintillating fiber beam halo detector for heavy ion beam diagnostics  

SciTech Connect

A prototype beam halo detector of scintillating Fibers has been designed in order to detect beam halo problems at an early stage in the tuning process. The results of initial characterization of the fibers are presented and issues of electronics and readout discussed.

McMahan, M.A.; Assang, A.; Herr, S.; McCormack, F.; Krebs, G.; Feinberg, B.

1993-05-01

150

Energy Resolution of Plastic Scintillation Detector for Beta Rays  

Microsoft Academic Search

Many experiments on neutrinoless double beta decays have been proposed recently for determining the effective mass of neutrinos. Some of them use a plastic scintillator for measuring the beta-ray energy. Achieving a high energy resolution is critical for neutrinoless double beta decay experiments (e.g., MOON and superNEMO). The motivation of this study is to investigate the energy resolution of a

H. H. Vo; S. Kanamaru; C. Marquet; H. Nakamura; M. Nomachi; F. Piquemal; J. S. Ricol; Y. Sugaya; K. Yasuda

2008-01-01

151

Active Inspection of Nuclear Materials Using {sup 4}He Scintillation Detectors  

SciTech Connect

The detection of fissionable materials by neutron and high-energy photon active interrogation methods is explored using {sup 4}He scintillation detectors to search for prompt and delayed neutron signature. The low electron density of {sup 4}He in addition to its pulse shape discrimination capability allows strong rejection of gamma radiation. For the detection of the prompt neutron signatures, this capability is important as the signal produced by induced fission is accompanied by intense gamma radiation. The nanosecond time resolution of {sup 4}He scintillation detectors can be used for time-of-flight measurements aimed at determining the energy of the emitted neutrons. For delayed neutron detection, the insensitivity to the low energy neutrons present from non-signal reactions is inherent. Unlike detectors requiring a moderator, this technology can easily be collimated to reduce sensitivity to neutrons from outside the field of interest. The performance of the detectors for these applications is studied using GEANT4 computer modeling, based on measured detector parameters. A comparison is made with technologies typically used for these applications, i.e. heavily shielded organic scintillators for prompt neutron detection and Cd-lined {sup 3}He neutron detectors for the detection of delayed neutrons.

Davatz, G.; Howard, A. [Arktis Radiation Detectors Ltd, Technoparkstrasse 1, 8005 Zurich (Switzerland); Institute for Particle Physics, ETH Zurich, Schafmattstrasse 20, 8093 Zurich (Switzerland); Chandra, R.; Gendotti, U. [Arktis Radiation Detectors Ltd, Technoparkstrasse 1, 8005 Zurich (Switzerland)

2011-12-13

152

Construction and performance of a dose-verification scintillation-fiber detector for proton therapy  

NASA Astrophysics Data System (ADS)

A multilayer scintillation-fiber detector has been developed for precision measurement of time-dependent dose verification in proton therapy. In order to achieve the time and position sensitivity required for the precision dose measurements, a prototype detector was constructed with double-clad 1-mm-thick scintillation fibers and 128-channel silicon photodiodes. The hole charges induced in each channel of the silicon photodiodes were amplified and processed with a charge-integration mode. The detector was tested with 45-MeV proton beams provided by the MC50 cyclotron at the Korea Institute of Radiological and Medical Science (KIRAMS). The detector response for a 45-MeV proton beam was agreed fairly well with the predicted by GEANT4 simulations. Furthermore, the quantitative accuracy appearing in the spatial distribution of the detector response measured for 20 s is in the order of 1%, whose accuracy is satisfactory to verify beam-induced dose in proton therapy. We anticipate that the detector composed of scintillation fibers and operating in the charge-integration mode allows us to perform quality measurement of dynamic therapeutic beams.

Lee, Suhyun; Hong, Byungsik; Lee, Kyong Sei; Mulilo, Benard; Keun Park, Sung

2013-10-01

153

Scintillator gamma-ray detectors with silicon photomultiplier readouts for high-energy astronomy  

NASA Astrophysics Data System (ADS)

Space-based gamma-ray detectors for high-energy astronomy face strict constraints of mass, volume, and power, and must endure harsh operating environments. Scintillator materials have a long history of successful operation under these conditions, and new materials offer greatly improved performance in terms of efficiency, time response, and energy resolution. The use of scintillators in space remains constrained, however, by the mass, volume, and fragility of the associated light readout device, typically a vacuum photomultiplier tube (PMT). Recently developed silicon photomultipliers (SiPMs) offer gains and efficiencies similar to those of PMTs, but with greatly reduced mass and volume, high ruggedness, and no high-voltage requirements. We have therefore been investigating the use of SiPM readouts for scintillator gamma-ray detectors, with an emphasis on their suitability for space- and balloonbased instruments for high-energy astronomy. We present our most recent results, including spectroscopy measurements for lanthanum bromide scintillators with SiPM readouts, and pulse-shape discrimination using organic scintillators with SiPM readouts. We also describe potential applications of SiPM readouts to specific highenergy astronomy instrument concepts.

Bloser, Peter F.; Legere, Jason; Bancroft, Christopher; McConnell, Mark L.; Ryan, James M.; Schwadron, Nathan

2013-09-01

154

Development of the dual scintillator sheet and Phoswich detector for simultaneous Alpha- and Beta-rays measurement  

SciTech Connect

Thin sheet type of ZnS(Ag)/plastic dual scintillator for simultaneous counting of alpha- and beta-particles using a organic and inorganic scintillator widely used in the radiation measurement was manufactured, which could be applicable in the contamination monitoring systems. Counting materials were manufactured by solidification of the scintillator solution which mixed scintillator, solvent, and polymer. Prepared dual scintillator is a counting material which can simultaneously measure the alpha- and beta-particles. It was divided into two parts : an inorganic scintillator layer for alpha-particle detection and an organic one for beta-particle detection. The organic layer was composed of 2,5-diphenyloxazole [PPO] and 1,4,-bis[5-phenyl(oxazolyl)benzene] [POPOP] acting as the scintillator and polysulfone acting as the polymer. The inorganic layer was composed of ZnS(Ag) as scintillator and polysulfone as paste. The ZnS(Ag) scintillator layer was printed onto the organic layer using screen printing method. To estimate the detection ability of the prepared counting materials, alpha-particle emitting nuclide, Am-241, and beta emitting nuclide, Sr/Y-90, were used. The scintillations produced by interaction between radiation and scintillator were measured by photomultiplier tube. The overall counting results reveal that the developed detector is efficient for simultaneous counting of alpha- and beta-particles. For application test, the dual scintillator was fabricated with a Phoswich detector for monitoring the in-pipe alpha and beta contamination. To deploy inside a pipe, two types of Phoswich detectors, sheets and cylinders, were prepared. For in-pipe monitoring, it was found that the cylindrical type was excellent. In the study, polymer composite counting material and Phoswich detectors were prepared using organic and inorganic scintillator for detecting different radiations. In the future, it will be applied to the contamination monitoring system for nuclear decommissioning sites, waste treatment sites, and similar areas. (authors)

Seo, B.K.; Kim, G.H.; Park, C.H.; Jung, Y.H.; Jung, C.H.; Lee, K.W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Han, M.J. [Kyungil Univ. (Korea, Republic of)

2007-07-01

155

Evaluation of Large Volume SrI2(Eu) Scintillator Detectors  

SciTech Connect

There is an ever increasing demand for gamma-ray detectors which can achieve good energy resolution, high detection efficiency, and room-temperature operation. We are working to address each of these requirements through the development of large volume SrI{sub 2}(Eu) scintillator detectors. In this work, we have evaluated a variety of SrI{sub 2} crystals with volumes >10 cm{sup 3}. The goal of this research was to examine the causes of energy resolution degradation for larger detectors and to determine what can be done to mitigate these effects. Testing both packaged and unpackaged detectors, we have consistently achieved better resolution with the packaged detectors. Using a collimated gamma-ray source, it was determined that better energy resolution for the packaged detectors is correlated with better light collection uniformity. A number of packaged detectors were fabricated and tested and the best spectroscopic performance was achieved for a 3% Eu doped crystal with an energy resolution of 2.93% FWHM at 662keV. Simulations of SrI{sub 2}(Eu) crystals were also performed to better understand the light transport physics in scintillators and are reported. This study has important implications for the development of SrI{sub 2}(Eu) detectors for national security purposes.

Sturm, B W; Cherepy, N J; Drury, O B; Thelin, P A; Fisher, S E; Magyar, A F; Payne, S A; Burger, A; Boatner, L A; Ramey, J O; Shah, K S; Hawrami, R

2010-11-18

156

Tagging radon daughters in low-energy scintillation detectors  

NASA Astrophysics Data System (ADS)

One problematic source of background in scintillator-based low-energy solar neutrino experiments such as Borexino is the presence of radon gas and its daughters. The mean lifetime of the ?-emitter 214Po in the radon chain is sufficiently short, 0.24 ms, that its decay, together with that immediately preceding of 214Bi, is easily recognized as a "coincidence event." This fact, combined with the capability of ?/? pulse-shape discrimination, makes it possible to tag decays of 222Rn and its first four daughters via a likelihood-based method.

McCarty, Kevin B.

2011-12-01

157

Radioactive threat detection using scintillant-based detectors  

NASA Astrophysics Data System (ADS)

An update to the performance of AS&E's Radioactive Threat Detection sensor technology. A model is presented detailing the components of the scintillant-based RTD system employed in AS&E products aimed at detecting radiological WMD. An overview of recent improvements in the sensors, electrical subsystems and software algorithms are presented. The resulting improvements in performance are described and sample results shown from existing systems. Advanced and future capabilities are described with an assessment of their feasibility and their application to Homeland Defense.

Chalmers, Alex

2004-09-01

158

In-phantom dose verification of prostate IMRT and VMAT deliveries using plastic scintillation detectors.  

PubMed

The goal of this work was to demonstrate the feasibility of using a plastic scintillation detector (PSD) incorporated into a prostate immobilization device to verify doses in vivo delivered during intensity-modulated radiation therapy (IMRT) and volumetric modulated-arc therapy (VMAT) for prostate cancer. The treatment plans for both modalities had been developed for a patient undergoing prostate radiation therapy. First, a study was performed to test the dependence, if any, of PSD accuracy on the number and type of calibration conditions. This study included PSD measurements of each treatment plan being delivered under quality assurance (QA) conditions using a rigid QA phantom. PSD results obtained under these conditions were compared to ionization chamber measurements. After an optimal set of calibration factors had been found, the PSD was combined with a commercial endorectal balloon used for rectal distension and prostate immobilization during external beam radiotherapy. This PSD-enhanced endorectal balloon was placed inside of a deformable anthropomorphic phantom designed to simulate male pelvic anatomy. PSD results obtained under these so-called "simulated treatment conditions" were compared to doses calculated by the treatment planning system (TPS). With the PSD still inserted in the pelvic phantom, each plan was delivered once again after applying a shift of 1 cm anterior to the original isocenter to simulate a treatment setup error.The mean total accumulated dose measured using the PSD differed the TPS-calculated doses by less than 1% for both treatment modalities simulated treatment conditions using the pelvic phantom. When the isocenter was shifted, the PSD results differed from the TPS calculations of mean dose by 1.2% (for IMRT) and 10.1% (for VMAT); in both cases, the doses were within the dose range calculated over the detector volume for these regions of steep dose gradient. Our results suggest that the system could benefit prostate cancer patient treatment by providing accurate in vivo dose reports during treatment and verify in real-time whether treatments are being delivered according to the prescribed plan. PMID:23180976

Klein, David; Briere, Tina Marie; Kudchadker, Rajat; Archambault, Louis; Beaulieu, Luc; Lee, Andrew; Beddar, Sam

2012-08-24

159

In-phantom dose verification of prostate IMRT and VMAT deliveries using plastic scintillation detectors  

PubMed Central

The goal of this work was to demonstrate the feasibility of using a plastic scintillation detector (PSD) incorporated into a prostate immobilization device to verify doses in vivo delivered during intensity-modulated radiation therapy (IMRT) and volumetric modulated-arc therapy (VMAT) for prostate cancer. The treatment plans for both modalities had been developed for a patient undergoing prostate radiation therapy. First, a study was performed to test the dependence, if any, of PSD accuracy on the number and type of calibration conditions. This study included PSD measurements of each treatment plan being delivered under quality assurance (QA) conditions using a rigid QA phantom. PSD results obtained under these conditions were compared to ionization chamber measurements. After an optimal set of calibration factors had been found, the PSD was combined with a commercial endorectal balloon used for rectal distension and prostate immobilization during external beam radiotherapy. This PSD-enhanced endorectal balloon was placed inside of a deformable anthropomorphic phantom designed to simulate male pelvic anatomy. PSD results obtained under these so-called “simulated treatment conditions” were compared to doses calculated by the treatment planning system (TPS). With the PSD still inserted in the pelvic phantom, each plan was delivered once again after applying a shift of 1 cm anterior to the original isocenter to simulate a treatment setup error. The mean total accumulated dose measured using the PSD differed the TPS-calculated doses by less than 1% for both treatment modalities simulated treatment conditions using the pelvic phantom. When the isocenter was shifted, the PSD results differed from the TPS calculations of mean dose by 1.2% (for IMRT) and 10.1% (for VMAT); in both cases, the doses were within the dose range calculated over the detector volume for these regions of steep dose gradient. Our results suggest that the system could benefit prostate cancer patient treatment by providing accurate in vivo dose reports during treatment and verify in real-time whether treatments are being delivered according to the prescribed plan.

Klein, David; Briere, Tina Marie; Kudchadker, Rajat; Archambault, Louis; Beaulieu, Luc; Lee, Andrew; Beddar, Sam

2012-01-01

160

Neutron measurements with lanthanum-bromide scintillation detectors—A first approach  

NASA Astrophysics Data System (ADS)

In this paper we report on the measurement of ?-rays using a 2 in.×2 in. LaBr3:Ce scintillation detector. The ?-rays were emitted in the spontaneous fission of 252Cf and detected in coincidence with fission fragments. After presenting some of the properties of the detector, we show how well ?-rays produced in different reactions may easily be distinguished by their characteristic time-of-flight. Then we focus on the analysis of ?-rays from inelastically scattered neutrons in the scintillation crystal and demonstrate how this information may be used for neutron spectroscopy. We determine the neutron detection efficiency and compare it to the result of calculations based on existing reaction cross-sections. Finally, we discuss the detection performance in relation to other detector systems commonly used for neutron monitoring.

Oberstedt, A.; Billnert, R.; Oberstedt, S.

2013-04-01

161

Simulation tool for optical design of PET detector modules including scintillator material and sensor array  

SciTech Connect

The appearance of single photon avalanche diodes (SPADs) in the field of PET detector modules made it necessary to apply more complex optical design methods to refine the performance of such assemblies. We developed a combined simulation tool that is capable to model complex detector structures including scintillation material, light guide, light collection optics and sensor, correctly taking into account the statistical behavior of emission of scintillation light and its absorbance in SPADs. As a validation we compared simulation results obtained by our software and another optical design program. Calculations were performed for a simple PET detector arrangement used for testing purposes. According to the results, deviation of center of gravity coordinates between the two simulations is 0.0195 mm, the average ratio of total counts 1.0052. We investigated the error resulting from finite sampling in wavelength space and we found that 20 nm pitch is sufficient for the simulation in case of the given spectral dependencies. (authors)

Jatekos, B.; Erdei, G.; Lorincz, E. [Budapest Univ. of Technology and Economics, Dept. of Atomic Physics, Budafoki ut 8, H-1111 Budapest (Hungary)

2011-07-01

162

Comparison of neutron sensitive scintillators for use with a solid-state optical detector  

NASA Astrophysics Data System (ADS)

The detection of illicit nuclear sources and SNM requires an ubiquitous network of sensors. While 3He proportional counters are excellent neutron detectors, there is an insufficient global supply of 3He to create the required number of detectors. Alternatives to 3He must be efficient, insensitive to gamma radiation, easily manufactured, rugged, and inexpensive to enable the procurement of a large numbers of sensors. The use of a high sensitivity solid-state optical detector coupled to scintillation materials, loaded with a neutron absorber such as 6Li or 10B, can fulfill these design constraints. In this work, we compare the properties of neutron-sensitive scintillation materials utilizing Monte Carlo simulations and experiments. Cs2LiLaBr6:Ce is compared to commercially available boron-loaded plastic scintillators and 3He tubes. The scintillators are compared for neutron detection efficiency, limitations on size, gamma-rejection ratio, neutron detection limits, manufacturing cost, and availability for mass-production.

Mukhopadhyay, Sharmistha; Stapels, Christopher; Johnson, Eric B.; Chapman, Eric C.; Linsay, Paul S.; Prettyman, Thomas H.; Squillante, Michael R.; Christian, James F.

2009-08-01

163

Timing resolution of scintillation-detector systems: a Monte Carlo analysis  

PubMed Central

Recent advancements in fast scintillating materials and fast photomultiplier tubes (PMTs) have stimulated renewed interest in time-of-flight (TOF) positron emission tomography (PET). It is well known that the improvement in the timing resolution in PET can significantly reduce the noise variance in the reconstructed image resulting in improved image quality. In order to evaluate the timing performance of scintillation detectors used in TOF PET, we use a Monte Carlo analysis to model the physical processes (crystal geometry, crystal surface finish, scintillator rise time, scintillator decay time, photoelectron yield, PMT transit time spread, PMT single-electron response, amplifier response, and time pick-off method) that can contribute to the timing resolution of scintillation-detector systems. In the Monte Carlo analysis, the photoelectron emissions are modeled by a rate function, which is used to generate the photoelectron time points. The rate function, which is simulated using Geant4, represents the combined intrinsic light emissions of the scintillator and the subsequent light transport through the crystal. The PMT output signal is determined by the superposition of the PMT single-electron response resulting from the photoelectron emissions. The transit time spread and the single-electron gain variation of the PMT are modeled in the analysis. Three practical time pick-off methods are considered in the analysis. Statistically, the best timing resolution is achieved with the first photoelectron timing. The calculated timing resolution suggests that a leading edge discriminator gives better timing performance than a constant fraction discriminator and produces comparable results when a 2-threshold or 3-threshold discriminator is used. For a typical PMT, the effect of detector noise on the timing resolution is negligible. The calculated timing resolution is found to improve with increasing mean photoelectron yield, decreasing scintillator decay time, and decreasing transit time spread. However, only substantial improvement in the timing resolution is obtained with improved transit time spread if the first photoelectron timing is less than the transit time spread. While the calculated timing performance does not seem to be affected by the pixel size of the crystal, it improves for an etched crystal compared to a polished crystal. In addition, the calculated timing resolution degrades with increasing crystal length. These observations can be explained by studying the initial photoelectron rate. Experimental measurements provide reasonably good agreement with the calculated timing resolution. The Monte Carlo analysis developed in this work will allow us to optimize the scintillation detectors for timing and to understand the physical factors limiting their performance.

Choong, Woon-Seng

2010-01-01

164

A new digital method for high precision neutron-gamma discrimination with liquid scintillation detectors  

NASA Astrophysics Data System (ADS)

A new pulse-shape discrimination algorithm for neutron and gamma (n/?) discrimination with liquid scintillation detectors has been developed, leading to a considerable improvement of n/? separation quality. The method is based on triangular pulse shaping which offers a high sensitivity to the shape of input pulses, as well as, excellent noise filtering characteristics. A clear separation of neutrons and ?-rays down to a scintillation light yield of about 65 keVee (electron equivalent energy) with a dynamic range of 45:1 was achieved. The method can potentially operate at high counting rates and is well suited for real-time measurements.

Nakhostin, M.

2013-05-01

165

A performance study on a phoswich detector consisting of an inner NE213 scintillator and an outer CaF 2(Eu) crystal wall  

Microsoft Academic Search

We developed a new phoswich detector. The detector consists of an inner NE213 organic liquid scintillator and an outer thin CaF2(Eu) crystal which are coupled to a photomultiplier. The charged particles produced in the NE213 scintillator by the interaction of radiation with the detector either stop in the NE213 scintillator or pass through both the NE213 scintillator and the outer

Masashi Takada; Tokushi Shibata; Yoshitomo Uwamino; Takashi Nakamura

1996-01-01

166

Dedicated x-ray scintillation detector for digital subtraction angiography using synchrotron radiation  

SciTech Connect

A one-coordinate x-ray detector for digital subtraction angiography using synchrotron radiation is described. It comprises two x-ray-sensitive lines, each having 128 independent channels of scintillation counters. The detector is designed to simultaneously measure the intensities of two linear monochromatic beams being 8--10 mm distant from each other. The spatial resolution of each line ranges from 0.2 to 2 mm. The maximum counting rate is 6 MHz for each channel, and the detection efficiency of the 33.2-keV quanta is close to 100%. Preliminary results of the testing of the detector channels on synchrotron radiation beam are given.

Dementiev, E. N.; Dolbnya, I. P.; Zagorodnikov, E. I.; Kolesnikov, K. A.; Kulipanov, G. N.; Kurylo, S. G.; Medvedko, A. S.; Mezentsev, N. A.; Pindyurin, V. F.; Cheskidov, V. G.; and others

1989-07-01

167

Radiation Hardness Tests of a Scintillation Detector with Wavelength Shifting Fiber Readout  

SciTech Connect

We have performed radiation tolerance tests on the BCF-99-29MC wavelength shifting fibers and the BC404 plastic scintillator from Bicron as well as on silicon rubber optical couplers. We used the 60Co gamma source at the Instituto de Ciencias Nucleares facility to irradiate 30-cm fiber samples with doses from 50 Krad to 1 Mrad. We also irradiated a 10x10 cm2 scintillator detector with the WLS fibers embedded on it with a 200 krad dose and the optical conectors between the scintillator and the PMT with doses from 100 to 300 krad. We measured the radiation damage on the materials by comparing the pre- and post-irradiation optical transparency as a function of time.

Alfaro, R.; Sandoval, A. [Instituto de Fisica - UNAM (Mexico); Cruz, E.; Martinez, M. I.; Paic, G. [Instituto de Ciencias Nucleares - UNAM (Mexico); Montano, L. M. [CINVESTAV (Mexico)

2006-09-25

168

Radiation Hardness Tests of a Scintillation Detector with Wavelength Shifting Fiber Readout  

NASA Astrophysics Data System (ADS)

We have performed radiation tolerance tests on the BCF-99-29MC wavelength shifting fibers and the BC404 plastic scintillator from Bicron as well as on silicon rubber optical couplers. We used the 60Co gamma source at the Instituto de Ciencias Nucleares facility to irradiate 30-cm fiber samples with doses from 50 Krad to 1 Mrad. We also irradiated a 10×10 cm2 scintillator detector with the WLS fibers embedded on it with a 200 krad dose and the optical conectors between the scintillator and the PMT with doses from 100 to 300 krad. We measured the radiation damage on the materials by comparing the pre- and post-irradiation optical transparency as a function of time.

Alfaro, R.; Cruz, E.; Martinez, M. I.; Montaño, L. M.; Paic, G.; Sandoval, A.

2006-09-01

169

Detection of the primary scintillation light from dense Ar, Kr and Xe with novel photosensitive gaseous detectors  

Microsoft Academic Search

The detection of primary scintillation light in combination with the charge or secondary scintillation signals is an efficient technique to determine the events t=0 as well as particle \\/ photon separation in large mass TPC detectors filled with noble gases and\\/or condensed noble gases. The aim of this work is to demonstrate that costly photo-multipliers could be replaced by cheap

L Periale; Vladimir Peskov; P J Carlson; T Francke; P Pavlopoulos; P Picchi; F Pietropaolo

2001-01-01

170

Spatial and spectral gamma-ray response of plastic scintillators used in portal radiation detectors; comparison of measurements and simulations  

Microsoft Academic Search

Portal radiation detectors are commonly used by steel industries in the probing and detection of radioactivity contamination in scrap metal. Furthermore, a large number of portal monitors are installed at the border crossings to prevent illegal radioactive material trafficking. These portal detectors typically consist of either PS (polystyrene) or PVT (polyvinyltoluene) plastic scintillating detectors. Through the electronic circuit of the

G. Takoudis; S. Xanthos; A. Clouvas; M. Antonopoulos-Domis; C. Potiriadis; J. Silva

2009-01-01

171

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

SciTech Connect

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

Cline, D.B.

1992-12-31

172

Organic scintillation detector response simulation using non-analog MCNPX-PoliMi  

SciTech Connect

Organic liquid scintillation detectors are valuable for the detection of special nuclear material since they are capable of detecting both neutrons and gamma rays. Scintillators can also provide energy information which is helpful in identification and characterization of the source. In order to design scintillation based measurement systems appropriate simulation tools are needed. MCNPX-PoliMi is capable of simulating scintillation detector response; however, simulations have traditionally been run in analog mode which leads to long computation times. In this paper, non-analog MCNPX-PoliMi mode which uses variance reduction techniques is applied and tested. The non-analog MCNPX-PoliMi simulation test cases use source biasing, geometry splitting and a combination of both variance reduction techniques to efficiently simulate pulse height distribution and then time-of-flight for a heavily shielded case with a {sup 252}Cf source. An improvement factor (I), is calculated for distributions in each of the three cases above to analyze the effectiveness of the non-analog MCNPX-PoliMi simulations in reducing computation time. It is found that of the three cases, the last case which uses a combination of source biasing and geometry splitting shows the most improvement in simulation run time for the same desired variance. For pulse height distributions speedup ranging from a factor 5 to 25 is observed, while for time-of-flights the speedup factors range from 3 to 10. (authors)

Prasad, S.; Clarke, S. D.; Pozzi, S. A.; Larsen, E. W. [Univ. of Michigan, 2355 Bonisteel Blvd., Ann Arbor, MI 48109 (United States)

2012-07-01

173

Characteristics of Un doped and Europium-dopedSrI2 Scintillator Detectors  

SciTech Connect

High energy resolution gamma-ray detectors that can be formed into relatively large sizes while operating at room temperature offer many advantages for national security applications. We are working toward that goal through the development of SrI{sub 2}(Eu) scintillator detectors, which routinely provide <;3.0% energy resolution at 662 keV with volumes >;10 cm{sup 3}. In this study, we have tested pure, undoped SrI{sub 2} to gain a better understanding of the scintillation properties and spectroscopic performance achievable without activation. An undoped crystal grown from 99.999% pure SrI{sub 2} pellets was tested for its spectroscopic performance, its light yield, and uniformity of scintillation light collection as a function of gamma-ray interaction position relative to the crystal growth direction. Undoped SrI{sub 2} was found to provide energy resolution of 5.3% at 662 keV, and the light collection nonuniformity varied by only 0.72% over the length of the crystal. Measurements of both a 3% Eu-doped and the undoped SrI{sub 2} crystal were carried out in the SLYNCI facility and indicate differences in their light yield non-proportionality. The surprisingly good scintillation properties of the pure SrI{sub 2} crystal suggests that with high-purity feedstock, further reduction of the Eu concentration can be made to grow larger crystals while not adversely impacting the spectroscopic performance.

Sturm, Benjamin [Lawrence Livermore National Laboratory (LLNL); Cherepy, Nerine [Lawrence Livermore National Laboratory (LLNL); Drury, Owen [Lawrence Livermore National Laboratory (LLNL); Thelin, P [Lawrence Livermore National Laboratory (LLNL); Fisher, S E [Lawrence Livermore National Laboratory (LLNL); O’Neal, S P [Lawrence Livermore National Laboratory (LLNL); Payne, Stephen A. [Lawrence Livermore National Laboratory (LLNL); Burger, Arnold [Fisk University, Nashville, TN; Boatner, Lynn A [ORNL; Ramey, Joanne Oxendine [ORNL; Shah, Kanai [Radiation Monitoring Devices, Watertown, MA; Hawrami, Rastgo [Fisk University, Nashville, TN

2012-01-01

174

Realization of a small-size high resolution linear neutron scintillation detector  

SciTech Connect

The spectrum of position sensitive neutron scintillation detectors, which have been developed and designed in the institute during the last decade, comprises several high resolution linear detectors. The design of the small size high resolution detector is based on a modified Anger technology using a linear array of 24 HAMAMATSU type R1770 rectangular photomultipliers and a 1 mm {sup 6}Li glass scintillator. The sensitive detector area is 200 x 20 mm{sup 2} and the spatial resolution is 1.2 mm. The neutron sensitivity at 1{angstrom} is about 65% and the residual gamma sensitivity is less than 10{sup {minus}4} and the maximum count rate is about 100 kHz. The detector is linked to a highly flexible PC-based data acquisition system with 12 bit position and 16 bit time resolution. The stand alone detector and data acquisition system is aimed preferably at pulsed sources performing high resolution angle-dispersive time-of-flight experiments.

Engels, R.; Reinartz, R.; Reinhart, P.; Schelten, J. [Forschungszentrum Juelich GmbH (Germany); Jansen, E.; Schaefer, W. [Univ. Bonn (Germany). Mineralogisches Inst.

1998-06-01

175

Messungen der Szintillationszeitkonstanten Anorganischer Kristalle fuer die Entwicklung Eines Dreifach-Phoswich - Detektors fuer Hochenergetische Roentgenquanten (Measurements of the Scintillation Time Constants of Inorganic Crystals for the Development of a Triple-Phoswich Detector for High-Energy X-ray Quanta).  

National Technical Information Service (NTIS)

A setup for the measurement of the rise time distribution of pulses measured by a triple-Phoswich detector that is planned as component of an imaging system of a rotation-modulation telescope (RMT) was built. The principles and characteristics of scintill...

T. Michelis

1987-01-01

176

Development of the Fast Scintillation Detector with Programmable High Voltage Adjustment Suitable for Moessbauer Spectroscopy  

SciTech Connect

This work is focused on a development of a compact fast scintillation detector suitable for Moessbauer spectroscopy (low energy X-ray/{gamma}-ray detection) where high counting rates are inevitable. Optimization of this part was necessary for a reliable function, better time resolution and to avoid a detector pulses pile-up effect. The pile-up effect decreases the measurement performance, significantly depends on the source activity and also on the pulse duration. Our new detection unit includes a fast scintillation crystal YAP:Ce, an R6095 photomultiplier tube, a high voltage power supply socket C9028-01 assembly, an AD5252 digital potentiometer with an I2C interface and an AD8000 ultra fast operation preamplifier. The main advantages of this solution lie in a short pulse duration (less than 200 ns), stable operation for high activities, programmable gain of the high voltage supply and compact design in the aluminum housing.

Prochazka, R.; Frydrych, J. [Center for Nanomaterial Research, Faculty of Science Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Pechousek, J. [Center for Nanomaterial Research, Faculty of Science Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Department of Experimental Physics, Faculty of Science, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic)

2010-07-13

177

Development of the Fast Scintillation Detector with Programmable High Voltage Adjustment Suitable for Mössbauer Spectroscopy  

NASA Astrophysics Data System (ADS)

This work is focused on a development of a compact fast scintillation detector suitable for Mössbauer spectroscopy (low energy X-ray/?-ray detection) where high counting rates are inevitable. Optimization of this part was necessary for a reliable function, better time resolution and to avoid a detector pulses pile-up effect. The pile-up effect decreases the measurement performance, significantly depends on the source activity and also on the pulse duration. Our new detection unit includes a fast scintillation crystal YAP:Ce, an R6095 photomultiplier tube, a high voltage power supply socket C9028-01 assembly, an AD5252 digital potentiometer with an I2C interface and an AD8000 ultra fast operation preamplifier. The main advantages of this solution lie in a short pulse duration (less than 200 ns), stable operation for high activities, programmable gain of the high voltage supply and compact design in the aluminum housing.

Prochazka, R.; Pechousek, J.; Frydrych, J.

2010-07-01

178

Two dimensional position sensitive scintillation neutron detector for the time-of-flight single crystal diffractometer at the IPNS  

Microsoft Academic Search

A two dimensional position sensitive neutron detector with an active area of 30 cm x 30 cm has been developed. The detector consists of a 7 x 7 array of 2-inch-square photomultiplier tubes (PMT's) in front of which is a 38 mm thick light disperser and a 2 mm thick ⁶Li--loaded, Ce-activated, glass scintillator. Each captured neutron produces a scintillation

A. J. Schultz; R. G. Teller; J. M. Williams; M. G. Strauss; R. Brenner

1982-01-01

179

Neutron-sensing scintillating glass optical fiber detectors  

SciTech Connect

Pacific Northwest Laboratory (PNL) has developed and tested the highest-transmission neutron-sensing glass fibers reported in the open literature to date. By developing glass compositions specifically for fiber drawing and by using superior oxidationstate controls and rapid quenching, PNL produces, fiber with useful lengths in excess of 200 cm. These long fibers can be used in detectors. Test results on the fibers used as a form-fitting detector around a small storage container containing neutron and gamma ray sources are reported. Excellent neutron-gamma ray discrimination has been achieved. These neutron-sensing glass optical fibers provide for new methods for monitoring the inventory of, preventing the diversion of, and detecting the unauthorized transport of sensitive nuclear materials. As such, it represents a significant potential element in countering the threat of nuclear terrorism.

Bliss, M.; Reeder, P.L.; Craig, R.A.

1994-07-01

180

Performance comparison of four compact room-temperature detectors – two cadmium zinc telluride (CZT) semiconductor detectors, a LaCl3(Ce) scintillator, and an NaI(Tl) scintillator  

SciTech Connect

The performance characteristics of four compact, room-temperature detectors – two scintillators and two semiconductor detectors – have been studied. All are commercially-available detectors. The two scintillators were a Æ13mmX13mm lanthanum chloride [LaCl3(Ce)] detector and a Æ25mmX25mm sodium iodide [NaI(Tl)] detector. The two semiconductor detectors were a 10X10X3 mm3 cadmium zinc telluride (CZT) detector with a coplanar gridded anode and a 5X5X5 mm3 CZT detector with an extended cathode. The efficiency, resolution, and peak shape performance of these devices are compared in this work. Since LaCl3(Ce) is a relatively new commercial scintillator material, additional information on the performance of this detector is presented. Specifically, we discuss the impact of naturally-occurring radioactive 138La on the background spectra measured with this scintillator. Additionally, two of the three LaCl3(Ce) crystals that we obtained commercially were internally contaminated with an alpha particle-emitting radionuclide which we have identified as 227Ac+daughters. This contamination had a profound impact on the usefulness of these two detectors.

J. K. Hartwell

2004-10-01

181

A thin plastic scintillator time-zero detector and flux monitor  

Microsoft Academic Search

A time-zero detector and beam flux monitor to be used with intermediate energy heavy ions has been developed. It is based on a self-supporting thin film of plastic scintillator placed at one focus of a high-quality ellipsoidal mirror. The light emitted is concentrated on the photocathode of a photomultiplier tube situated at the other focus. The performance with respect to

A. Galindo-Uribarri; T. E. Drake; G. C. Ball; N. C. Bray; J. S. Forster; E. Hagberg; D. Horn; C. Pruneau

1991-01-01

182

Using handheld plastic scintillator detectors to triage individuals exposed to a radiological dispersal device  

SciTech Connect

After a radiological dispersal device (RDD) event, people could become internally contaminated by inhaling dispersed radioactive particles. A rapid method to screen individuals who are internally contaminated is desirable. Such initial screening can help in prompt identification of those who are highly contaminated and in prioritizing individuals for further and more definitive evaluation such as laboratory testing. The use of handheld plastic scintillators to rapidly screen those exposed to an RDD with gamma-emitting radionuclides was investigated in this study. The Monte Carlo N-Particle transport code was used to model two commercially available plastic scintillation detectors in conjunction with anthropomorphic phantom models to determine the detector response to inhaled radionuclides. Biokinetic models were used to simulate an inhaled radionuclide and its progression through the anthropomorphic phantoms up to 30 d after intake. The objective of the study was to see if internal contamination levels equivalent to 250 mSv committed effective dose equivalent could be detected using these instruments. Five radionuclides were examined: {sup 60}Co, {sup 137}Cs, {sup 192}Ir, {sup 131}I and {sup 241}Am. The results demonstrate that all of the radionuclides except {sup 241}Am could be detected when placing either one of the two plastic scintillator detector systems on the posterior right torso of the contaminated individuals.

Manger, Ryan P [ORNL; Hertel, Nolan [Georgia Institute of Technology; Burgett, E. [Georgia Institute of Technology; Ansari, A. [Centers for Disease Control and Prevention

2011-01-01

183

Scintillation detector efficiencies for neutrons in the energy region above 20 MeV  

SciTech Connect

The computer program SCINFUL (for SCINtillator FUL1 response) is a program designed to provide a calculated complete pulse-height response anticipated for neutrons being detected by either an NE-213 (liquid) scintillator or an NE-110 (solid) scintillator in the shape of a right circular cylinder. The point neutron source may be placed at any location with respect to the detector, even inside of it. The neutron source may be monoenergetic, or Maxwellian distributed, or distributed between chosen lower and upper bounds. The calculational method uses Monte Carlo techniques, and it is relativistically correct. Extensive comparisons with a variety of experimental data have been made. There is generally overall good agreement (less than 10% differences) of results for SCINFUL calculations with measured integral detector efficiencies for the design incident neutron energy range of 0.1 to 80 MeV. Calculations of differential detector responses, i.e. yield versus response pulse height, are generally within about 5% on the average for incident neutron energies between 16 and 50 MeV and for the upper 70% of the response pulse height. For incident neutron energies between 50 and 80 MeV, the calculated shape of the response agrees with measurements, but the calculations tend to underpredict the absolute values of the measured responses. Extension of the program to compute responses for incident neutron energies greater than 80 MeV will require new experimental data on neutron interactions with carbon. 32 refs., 6 figs., 2 tabs.

Dickens, J.K.

1991-01-01

184

A Geant4 simulation code for simulating optical photons in SPECT scintillation detectors  

NASA Astrophysics Data System (ADS)

Geant4 is an object oriented toolkit created for the simulation of High-Energy Physics detectors. Geant4 allows an accurate modeling of radiation sources and detector devices, with easy configuration and friendly interface and at the same time with great accuracy in the simulation of physical processes. While most Monte Carlo codes do not allow the simulation of the transport and boundary characteristics for optical photons transport generated by scintillating crystal, Geant4 allows the simulation of the optical photons. In this paper we present an application of the Geant4 program for simulating optical photons in SPECT cameras. We aim to study the light transport within scintillators, photomultiplier tubes and coupling devices. To this end, we simulated a detector based on a scintillator, coupled to a photomultiplier tube through a glass window. We compared simulated results with experimental data and theoretical models, in order to verify the good matching with our simulations. We simulated a pencil beam of 140 keV photons impinging the crystal at different locations. For each condition, we calculated the value of the Pulse Height Centroid and the spread of the charge distribution, as read out by the anode array of the photomultiplier. Finally, the spatial and the energy resolutions of the camera have been estimated by simulated data. In all cases, we found that simulations agree very well with experimental data.

Lo Meo, S.; Bennati, P.; Cinti, M. N.; Lanconelli, N.; Navarria, F. L.; Pani, R.; Pellegrini, R.; Perrotta, A.; Vittorini, F.

2009-07-01

185

Using handheld plastic scintillator detectors to triage individuals exposed to a radiological dispersal device.  

PubMed

After a radiological dispersal device (RDD) event, people could become internally contaminated by inhaling dispersed radioactive particles. A rapid method to screen individuals who are internally contaminated is desirable. Such initial screening can help in prompt identification of those who are highly contaminated and in prioritising individuals for further and more definitive evaluation such as laboratory testing. The use of handheld plastic scintillators to rapidly screen those exposed to an RDD with gamma-emitting radionuclides was investigated in this study. The Monte Carlo N-Particle transport code was used to model two commercially available plastic scintillation detectors in conjunction with anthropomorphic phantom models to determine the detector response to inhaled radionuclides. Biokinetic models were used to simulate an inhaled radionuclide and its progression through the anthropomorphic phantoms up to 30 d after intake. The objective of the study was to see if internal contamination levels equivalent to 250 mSv committed effective dose equivalent could be detected using these instruments. Five radionuclides were examined: (60)Co, (137)Cs, (192)Ir, (131)I and (241)Am. The results demonstrate that all of the radionuclides except (241)Am could be detected when placing either one of the two plastic scintillator detector systems on the posterior right torso of the contaminated individuals. PMID:22128361

Manger, R P; Hertel, N E; Burgett, E A; Ansari, A

2011-11-28

186

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

SciTech Connect

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)].

Garcia-Munoz, M.; Fahrbach, H.-U.; Zohm, H. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association Boltzmannstr. 2, D-85748 Garching (Germany); Collaboration: ASDEX Upgrade Team

2009-05-15

187

Near midplane scintillator-based fast ion loss detector on DIII-D  

SciTech Connect

A new scintillator-based fast-ion loss detector (FILD) installed near the outer midplane of the plasma has been commissioned on DIII-D. This detector successfully measures coherent fast ion losses produced by fast-ion driven instabilities ({<=}500 kHz). Combined with the first FILD at {approx}45 Degree-Sign below the outer midplane [R. K. Fisher, et al., Rev. Sci. Instrum. 81, 10D307 (2010)], the two-detector system measures poloidal variation of losses. The phase space sensitivity of the new detector (gyroradius r{sub L}{approx}[1.5-8] cm and pitch angle {alpha}{approx}[35 Degree-Sign -85 Degree-Sign ]) is calibrated using neutral beam first orbit loss measurements. Since fast ion losses are localized poloidally, having two FILDs at different poloidal locations allows for the study of losses over a wider range of plasma shapes and types of loss orbits.

Chen, X.; Heidbrink, W. W. [University of California-Irvine, Irvine, California (United States); Fisher, R. K.; Pace, D. C.; Chavez, J. A.; Van Zeeland, M. A. [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Garcia-Munoz, M. [Max-Planck Institut fur Plasmaphysiks, Garching (Germany)

2012-10-15

188

Identification of prompt fission ?-rays with lanthanum-chloride scintillation detectors  

NASA Astrophysics Data System (ADS)

In this paper we demonstrate the employment of LaCl3:Ce scintillation detectors for the identification of prompt fission ?-rays from ?-radiation in contrast to other reactions. We present the properties of cylindrical 1.5 in.×1.5 in. detectors in terms of intrinsic activity, energy resolution, intrinsic full peak efficiency and intrinsic timing resolution. In addition, we show results from the measurement of ?-rays emitted in coincidence with the spontaneous fission of 252Cf, which lead us to the conclusion that the properties of the detectors used in this work, in particular the good timing resolution and a reasonably good energy resolution, are more than just sufficient for the assessment of prompt ?-heat in future nuclear reactors as requested by the OECD. Hence, in our opinion, LaCl3:Ce detectors, compared to those made out of LaBr3:Ce crystals, represent an appropriate and quasi low-cost choice for the above mentioned applications.

Oberstedt, A.; Oberstedt, S.; Billnert, R.; Geerts, W.; Hambsch, F.-J.; Karlsson, J.

2012-03-01

189

High spatial resolution radiation detectors based on hydrogenated amorphous silicon and scintillator  

NASA Astrophysics Data System (ADS)

Hydrogenated amorphous silicon (a-Si:H) as a large-area thin film semiconductor with ease of doping and low-cost fabrication capability has given a new impetus to the field of imaging sensors; its high radiation resistance also makes it a good material for radiation detectors. In addition, large-area microelectronics based on a-Si:H or polysilicon can be made with full integration of peripheral circuits, including readout switches and shift registers on the same substrate. Thin a-Si:H p-i-n photodiodes coupled to suitable scintillators are shown to be suitable for detecting charged particles, electrons, and X-rays. The response speed of CsI/a-Si:H diode combinations to individual particulate radiation is limited by the scintillation light decay since the charge collection time of the diode is very short (less than 10 ns). The reverse current of the detector is analyzed in term of contact injection, thermal generation, field enhanced emission (Poole-Frenkel effect), and edge leakage. A good collection efficiency for a diode is obtained by optimizing the p layer of the diode thickness and composition. The CsI(Tl) scintillator coupled to an a-Si:H photodiode detector shows a capability for detecting minimum ionizing particles with S/N approx. 20. In such an arrangement a p-i-n diode is operated in a photovoltaic mode (reverse bias). In addition, a p-i-n diode can also work as a photoconductor under forward bias and produces a gain yield of 3--8 for shaping times of 1 micro s. The mechanism of the formation of structured CsI scintillator layers is analyzed. Initial nucleation in the deposited layer is sensitive to the type of substrate medium, with imperfections generally catalyzing nucleation. Therefore, the microgeometry of a patterned substrate has a significant effect on the structure of the CsI growth.

Jing, T.

1995-05-01

190

Investigations of surface coatings to reduce memory effect in plastic scintillator detectors used for radioxenon detection  

NASA Astrophysics Data System (ADS)

In this work Al2O3 and SiO2 coatings are tested as Xe diffusion barriers on plastic scintillator substrates. The motivation is improved beta-gamma coincidence detection systems, used to measure atmospheric radioxenon within the verification regime of the Comprehensive Nuclear-Test-Ban Treaty. One major drawback with the current setup of these systems is that the radioxenon tends to diffuse into the plastic scintillator material responsible for the beta detection, resulting in an unwanted memory effect. Here, coatings with thicknesses between 20 and 900 nm have been deposited onto plastic scintillators, and investigated using two different experimental techniques. The results show that all tested coatings reduce the Xe diffusion into the plastic. The reduction is observed to increase with coating thickness for both coating materials. The 425 nm Al2O3 coating is the most successful one, presenting a diffusion reduction of a factor 100, compared to uncoated plastic. In terms of memory effect reduction this coating is thus a viable solution to the problem in question.

Bläckberg, L.; Fay, A.; Jõgi, I.; Biegalski, S.; Boman, M.; Elmgren, K.; Fritioff, T.; Johansson, A.; Mårtensson, L.; Nielsen, F.; Ringbom, A.; Rooth, M.; Sjöstrand, H.; Klintenberg, M.

2011-11-01

191

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

NASA Astrophysics Data System (ADS)

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 ?-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 ?m) 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.

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

2008-08-01

192

Investigation of three-dimensional localisation of radioactive sources using a fast organic liquid scintillator detector  

NASA Astrophysics Data System (ADS)

In this paper we discuss the possibility of locating radioactive sources in space using a scanning-based method, relative to the three-dimensional location of the detector. The scanning system comprises an organic liquid scintillator detector, a tungsten collimator and an adjustable equatorial mount. The detector output is connected to a bespoke fast digitiser (Hybrid Instruments Ltd., UK) which streams digital samples to a personal computer. A radioactive source has been attached to a vertical wall and the data have been collected in two stages. In the first case, the scanning system was placed a couple of metres away from the wall and in the second case it moved few centimetres from the previous location, parallel to the wall. In each case data were collected from a grid of measurement points (set of azimuth angles for set of elevation angles) which covered the source on the wall. The discrimination of fast neutrons and gamma rays, detected by the organic liquid scintillator detector, is carried out on the basis of pulse gradient analysis. Images are then produced in terms of the angular distribution of events for total counts, gamma rays and neutrons for both cases. The three-dimensional location of the neutron source can be obtained by considering the relative separation of the centres of the corresponding images of angular distribution of events. The measurements have been made at the National Physical Laboratory, Teddington, Middlesex, UK.

Gamage, K. A. A.; Joyce, M. J.; Taylor, G. C.

2013-04-01

193

A setup for precise measurement of resonance neutron capture by self-indication  

Microsoft Academic Search

In order to measure neutron capture self-indication in the neutron energy range up to 200 keV, a setup based on a 16-section NaI(Tl) scintillation gamma detector has been created at the 500-m flight path of the IBR-30 booster (JINR-Dubna). The detector has a geometric efficiency of 80% and a total scintillator volume of 36 1. The capture self-indication ratio Tgamma(n)

N. Janeva; S. Toshkov; G. V. Muradyan; Yu. V. Grigorjev; G. Georgiev; I. Sirakov; V. G. Tishin; Yu. S. Zamjatnin

1992-01-01

194

A Minor Modification of Leading Edge Discriminator Circuitry with a Delay Line for Baseline Restoration of Scintillation Detectors  

SciTech Connect

Multi-channel neutron time-of-flight detector arrays LaNSA, T-ion, Medusa, and Mandala, have been used for neutron spectroscopy in inertial confinement fusion experiments. These multi-channel neutron detector arrays consist of many identical scintillation detectors (842 {approx} 1024 channel), data acquisition electronics (discriminators, time-to digital converters, and controller). Each detector element is operated in neutron counting mode. Time-of-flight of individual detected neutrons are recorded by time to digital converters. The energy of each detected neutrons is determined from its time-of-flight. The accurate time measurement ({Delta}t {approx} 0.5 ns) and straightforward statistical features of the data obtained with these systems provides good integrity and reliability. The elements detector used in these systems are organic scintillators coupled with photo multiplier tubes. A scintillation detector operated in particle-counting mode requires finite recovery time after each detection event. The recovery time is determined by the time responses of scintillators, photo multiplier tubes, and the dead times of following discriminators and time-to digital converters. The harsh gamma ray background environment of fast ignitor experiments requires detectors that have fast recovery times. In high intensity laser experiments (I > 10{sup 19} W/cm{sup 2}), strong gamma ray bursts are produced by relativistic laser plasma interactions. Prior to the neutron signal, these strong gamma ray bursts hit the detectors and interfere with the detection of following neutron signals. In these situations, the recovery time of the system after preceding gamma ray bursts is determined mainly by the base line shift of the PMT signal (due to slower decay components of scintillators ''after glow''). Discriminators cannot detect following signal pulses until the proceeding burst decays below its threshold voltage. The base line shift caused by the after glow prolongs the recovery time of the discriminators. Typical organic scintillators have slow decay component with 300 {approx} 600 nsec.

Izumi, N

2003-05-27

195

High Spatial Resolution Radiation Detectors Based on Hydrogenated Amorphous Silicon and Scintillator  

NASA Astrophysics Data System (ADS)

Hydrogenated amorphous silicon (a-Si:H) as a large -area thin film semiconductor with ease of doping and low -cost fabrication capability has given a new impetus to the field of imaging sensors; its high radiation resistance also makes it a good material for radiation detectors. In addition, large-area microelectronics based on a-Si:H or polysilicon can be made with full integration of peripheral circuits, including readout switches and shift registers on the same substrate. Thin a-Si:H p-i-n photodiodes coupled to suitable scintillators are shown to be suitable for detecting charged particles, electrons, and X-rays. The response speed of CsI/a-Si:H diode combinations to individual particulate radiation is limited by the scintillation light decay since the charge collection time of the diode is very short (<10ns). The reverse current of the detector is analyzed in term of contact injection, thermal generation, field enhanced emission (Poole-Frenkel effect), and edge leakage. A good collection efficiency for a diode is obtained by optimizing the p layer of the diode thickness and composition. The CsI(Tl) scintillator coupled to an a-Si:H photodiode detector shows a capability for detecting minimum ionizing particles with S/N ~20. In such an arrangement a p-i-n diode is operated in a photovoltaic mode (reverse bias). In addition, a p-i-n diode can also work as a photoconductor under forward bias and produces a gain yield of 3-8 for shaping times of 1 mus. The mechanism of the formation of structured CsI scintillator layers is analyzed. Initial nucleation in the deposited layer is sensitive to the type of substrate medium, with imperfections generally catalyzing nucleation. Therefore, the microgeometry of a patterned substrate has a significant effect on the structure of the CsI growth. CsI films with internal columnar structure developed using techniques described have produced greater X-ray detection sensitivity and higher spatial resolution than presently available commercial scintillator screens.

Jing, Tao

1995-01-01

196

A scintillating plastic fiber tracking detector for neutron and proton imaging and spectroscopy  

NASA Astrophysics Data System (ADS)

We report on a prototype detector system designed to perform imaging and spectroscopy on 20-250MeV neutrons. The detection techniques employed can be applied to measurements in a variety of disciplines including solar and atmospheric physics, radiation therapy and nuclear materials monitoring. The detector measures the energy and direction of neutrons by detecting double neutron-proton scatters and recording images of the ionization tracks of the recoil protons in a densely packed bundle of scintillating plastic fibers stacked in orthogonal layers. The scintillation tracks are detected and imaged by photomultipliers and image intensifier/CCD camera optics. By tracking the recoil protons from individual neutrons, the kinematics of the scatter are determined. This directional information results in a high signal-to-noise measurement. The self-triggering and track imaging features of a prototype for tracking in two dimensions are demonstrated in calibrations with 14-65MeV neutrons, 20-67.5MeV protons, and with cosmic-ray muons. Preliminary results of phantom imaging measurements using a proton beam are also presented. We discuss several applications for this detector technique and outline future development work.

Ryan, J. M.; Castaneda, C. M.; Holslin, D.; Macri, J. R.; McConnell, M. L.; Romero, J. L.; Wunderer, C. B.

1999-02-01

197

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

NASA Astrophysics Data System (ADS)

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/.

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

198

Extended algorithm for simulation of light transport in single crystal scintillation detectors for S(T)EM.  

PubMed

The new extended Monte Carlo (MC) simulation method for photon transport in S(T)EM back scattered electron (BSE) scintillation detection systems of various shapes is presented in this paper. The method makes use of the random generation of photon emission from a scintillator luminescent centre and describes the trajectory of photons and the efficiency of their transport toward the photocathode of the photomultiplier tube. The paper explains a new algorithm for determining the position of interaction of the photon with the surface of the single crystal scintillator or of the light guide with nearly arbitrary shapes. Some examples of the utilization of the simulation method are also included, and conclusions for very simple edge-guided signal (EGS) scintillation detection systems made. The computer optimized design of the BSE scintillation detector for the S 4000 Hitachi SEM was chosen to demonstrate the capability of this MC simulation method. PMID:17957744

Schauer, Petr

199

Development of a gated scintillation fiber neutron detector for areal density measurements of inertial confinement fusion capsules  

NASA Astrophysics Data System (ADS)

A detector for fuel areal density measurements in inertial confinement fusion capsules has been designed. Observation of neutrons scattered in an imploded deuterium capsule (0.27-0.6 MeV) is a promising method for areal density measurements in the National Ignition Facility DD surrogate capsules. In order to detect scattered neutrons, we need to (1) suppress interference due to the strong direct neutron burst and (2) suppress the background produced by neutrons scattering on nontarget material (mainly from the target chamber). In our detector system, we suppress direct neutrons by gating the detector. We suppress the nontarget background neutrons by placing the detector outside the target chamber and limiting the view of the detector with collimators. In addition, we are developing a lithium-glass scintillation-fiber detector (LG-SCIFI) to detect the scattered neutrons. The LG-SCIFI will work as a multichannel scintillator array. The scintillation signal will be amplified by a microchannel plate image intensifier, which is gated to accept signals only in a specific time-of-flight window for the scattered neutrons. The gated scintillation image will be recorded by a charge-coupled device. Since the detector is segmented, neutron detection events will be clearly identified as bright spots in the gated image.

Izumi, N.; Lerche, R. A.; Phillips, T. W.; Schmid, G. J.; Moran, M. J.; Koch, J. A.; Azechi, H.; Sangster, T. C.

2003-03-01

200

Target set-up for measurements with the use of a Si-ball detector  

Microsoft Academic Search

The thin n–p+ layer of Si n+–n–p+ wafers composing the light charged particles detectors can be easily damaged by scattered beam projectiles or heavy products of the nuclear reaction in target material. Such damages of the sensitive part of the wafer may in consequence shorten the detector life-time. This could be avoided by protecting the sensitive part of the detector

A. Kordyasz; A. Stolarz; J. Mierzejewski

2011-01-01

201

Alignment of the Near Detector scintillator modules using cosmic ray muons  

SciTech Connect

The authors describe the procedures and the results of the first alignment of the Near Detector. Using 15.5 million cosmic ray muon tracks, collected from October, 2004 through early january, 2005, they derive the effective transverse positions of the calorimeter scintillator modules. The residuals from straight line fits indicate that the current alignment has achieved better than 1 mm precision. They estimate the size of the remaining misalignment and using tracks recorded with a magnetic field test the effect of the magnetic field on the alignment.

Ospanov, Rustem; Lang, Karol; /Texas U.

2008-05-01

202

Timing resolution improvement using DOI information in a four-layer scintillation detector for TOF-PET  

Microsoft Academic Search

Depth-of-interaction (DOI) detectors are considered to be advantageous for time-of-flight positron emission tomography (TOF-PET) because they can correct timing errors arising in the scintillation crystals due to a propagation speed difference between annihilation radiation and scintillation photons. We experimentally measured this timing error, using our four-layer DOI encoding method. The upper layers exhibited the larger timing delays due to the

Kengo Shibuya; Fumihiko Nishikido; Tomoaki Tsuda; Tetsuya Kobayashi; Chihfung Lam; Taiga Yamaya; Eiji Yoshida; Naoko Inadama; Hideo Murayama

2008-01-01

203

Detection of the primary scintillation light from dense Ar, Kr and Xe with novel photosensitive gaseous detectors  

Microsoft Academic Search

The detection of primary scintillation light in combination with the charge or secondary scintillation signals is an efficient technique in determining the events “t=0” as well as particle\\/photon separation in large mass TPC detectors filled with noble gases and\\/or condensed noble gases.The aim of this work is to demonstrate that costly photo-multipliers could be replaced by cheap novel photosensitive gaseous

L. Periale; V. Peskov; P. Carlson; T. Francke; P. Pavlopoulos; P. Picchi; F. Pietropaolo

2002-01-01

204

Measurement of the spectral fluence rate of reference neutron sources with a liquid scintillation detector.  

PubMed

Reference neutron sources such as (241)AmBe(alpha,n) and (252)Cf are commonly used to calibrate neutron detectors for radiation protection purposes. The calibration factors of these detectors depend on the spectral distribution of the neutron fluence from the source. Differences between the spectral fluence of the neutron source and the ISO-recommended reference spectra might be caused by the properties of the individual source. The spectral neutron fluence rates of different reference neutron sources used at PTB were measured with a liquid scintillation detector (NE213), using maximum entropy unfolding and a new, experimentally determined detector response matrix. The detector response matrix was determined by means of the time-of-flight technique at a pulsed neutron source with a broad energy distribution realised at the PTB accelerator facility. The results of the measurements of the reference sources are compared with the ISO-recommended reference spectra. For the PTB (241)AmBe(alpha,n) reference source, the spectral neutron fluence was determined by means of a high-resolution (3)He semiconductor sandwich spectrometer in 1982. These measurements were the basis for the ISO recommendations. The current measurements confirm the high-energy part (E(n) > 2 MeV) of this spectrum and demonstrate the suitability of this new method for high-resolution spectrometry of broad neutron spectra. PMID:17553863

Zimbal, A

2007-06-06

205

Digital discrimination of neutrons and gamma-rays in organic scintillation detectors using moment analysis  

NASA Astrophysics Data System (ADS)

Digital discrimination of neutron and gamma-ray events in an organic scintillator has been investigated by moment analysis. Signals induced by an americium-beryllium (Am/Be) isotropic neutron source in a stilbene crystal detector have been sampled with a flash analogue-to-digital converter (ADC) of 1 GSamples/s sampling rate and 10-bit vertical resolution. Neutrons and gamma-rays have been successfully discriminated with a threshold corresponding to gamma-ray energy about 217 keV. Moment analysis has also been verified against the results assessed by a time-of-flight (TOF) measurement. It is shown that the classification of neutrons and gamma-rays afforded by moment analysis is consistent with that achieved by digital TOF measurement. This method has been applied to analyze the data acquired from the stilbene crystal detector in mixed radiation field of the HL-2A tokamak deuterium plasma discharges and the results are described.

Xie, Xufei; Zhang, Xing; Yuan, Xi; Chen, Jinxiang; Li, Xiangqing; Zhang, Guohui; Fan, Tieshuan; Yuan, Guoliang; Yang, Jinwei; Yang, Qingwei

2012-09-01

206

Digital discrimination of neutrons and gamma-rays in organic scintillation detectors using moment analysis.  

PubMed

Digital discrimination of neutron and gamma-ray events in an organic scintillator has been investigated by moment analysis. Signals induced by an americium-beryllium (Am/Be) isotropic neutron source in a stilbene crystal detector have been sampled with a flash analogue-to-digital converter (ADC) of 1 GSamples/s sampling rate and 10-bit vertical resolution. Neutrons and gamma-rays have been successfully discriminated with a threshold corresponding to gamma-ray energy about 217 keV. Moment analysis has also been verified against the results assessed by a time-of-flight (TOF) measurement. It is shown that the classification of neutrons and gamma-rays afforded by moment analysis is consistent with that achieved by digital TOF measurement. This method has been applied to analyze the data acquired from the stilbene crystal detector in mixed radiation field of the HL-2A tokamak deuterium plasma discharges and the results are described. PMID:23020376

Xie, Xufei; Zhang, Xing; Yuan, Xi; Chen, Jinxiang; Li, Xiangqing; Zhang, Guohui; Fan, Tieshuan; Yuan, Guoliang; Yang, Jinwei; Yang, Qingwei

2012-09-01

207

Digital discrimination of neutrons and gamma-rays in organic scintillation detectors using moment analysis  

SciTech Connect

Digital discrimination of neutron and gamma-ray events in an organic scintillator has been investigated by moment analysis. Signals induced by an americium-beryllium (Am/Be) isotropic neutron source in a stilbene crystal detector have been sampled with a flash analogue-to-digital converter (ADC) of 1 GSamples/s sampling rate and 10-bit vertical resolution. Neutrons and gamma-rays have been successfully discriminated with a threshold corresponding to gamma-ray energy about 217 keV. Moment analysis has also been verified against the results assessed by a time-of-flight (TOF) measurement. It is shown that the classification of neutrons and gamma-rays afforded by moment analysis is consistent with that achieved by digital TOF measurement. This method has been applied to analyze the data acquired from the stilbene crystal detector in mixed radiation field of the HL-2A tokamak deuterium plasma discharges and the results are described.

Xie Xufei; Zhang Xing; Yuan Xi; Chen Jinxiang; Li Xiangqing; Zhang Guohui; Fan Tieshuan [School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing (China); Yuan Guoliang; Yang Jinwei; Yang Qingwei [Southwestern Institute of Physics, Chengdu (China)

2012-09-15

208

Temperature characterization of scintillation detectors using solid-state photomultipliers for radiation monitoring applications  

NASA Astrophysics Data System (ADS)

We have characterized two state-of-the-art solid-state photomultipliers, one by SensL, the other by Hamamatsu, coupled to scintillators by Saint-Gobain Crystals in the -25 to +50 °C temperature range. At room temperature, the energy resolution at 661.6 keV measured with both detectors is worse than the resolution obtained when the crystals are coupled to a regular photomultiplier tube. Both the pulse height and pulse height resolution of the 661.6 keV gamma rays in the 137Cs spectrum vary strongly with temperature. The noise threshold determined from the 22Na spectrum increases quadratically as the temperature is increased to well above 100 keV at +50 °C for both detectors.

Tur, Clarisse; Solovyev, Vladimir; Flamanc, Jérémy

2010-08-01

209

Conceptual design of a scintillation fiber neutron detector for ? R measurements in ICF  

NASA Astrophysics Data System (ADS)

In implosion experiments at NIF, the areal density (? R) of maximum compression timing will be high ( ~ 1g/cm^2 ). For low temperature deuterium filled capsules, ? R measurements with ion spectroscopy will be difficult because ion stopping will be significant. A downshifted primary neutron counting method is a promising alternative. The neutron-scattering probability in the capsule is proportional to the ? R. The spectrum of neutrons scattered by the specific target nucleus has a characteristic low energy cut off. This enables separate, simultaneous measurements of fuel and pusher ? Rs. For this purpose, the detector should have sufficient sensitivity and dynamic range for low energy neutrons. A lithium-glass scintillation-fiber (LG-SCIFI) is a promising candidate. Details of the detector instrumentation and collimator design will be reported. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Izumi, N.; Lerche, R. A.; Phillips, T. W.; Schmid, G. J.; Moran, M. J.; Hatchett, S. P.; Sangster, T. C.

2001-10-01

210

On the elimination of the afterglow of CsI(Tl) scintillation detector  

NASA Astrophysics Data System (ADS)

The use of CsI(Tl) in survey meters is limited to low dose-rate fields due to the afterglow effect, which can take up to 20 min in case of 120 s exposure to 4 R/h field. Even mixtures of low and high dose-rate fields are prohibited since the afterglow effect of the high dose-rate field prevents the use of the meter in the low dose-rate field. It was found that heating the scintillation detector to 60 °C shortened considerably the time of the afterglow effect to 3 s, even after exposure of 120 s to fields of 4 R/h. It is suggested to start heating the detector immediately when reaching high dose-rate field and adjusting the calibration to the measured temperature.

Alfassi, Z. B.; Ifergan, Y.; Wengrowicz, U.; Weinstein, Marcelo

2009-07-01

211

Calorimeter prototype based on silicon drift detectors coupled to scintillators for Compton telescopes application  

NASA Astrophysics Data System (ADS)

The project of a new calorimeter module for Compton telescopes based on an array of silicon drift detectors (SDD) coupled to thallium activated cesium iodide (CsI(Tl)) scintillating crystals is presented. Because of their low output capacitance and the possibility to have the first amplifying stage directly integrated on chip, SDDs show better noise performances than traditional p-intrinsic-n (PIN) photodiodes. For this reason, SDDs coupled to scintillators show a higher energy resolution than similar systems based on PIN photodiodes. The detectors will be integrated in an array with read-out based on custom made ASIC's built to match with the SDDs electrical properties. Shaped signals are digitally converted by a Digital Front-End Electronic Board which also takes care of ASICs handshaking. The system architecture is based on the PICsIT instrument on board the INTEGRAL satellite, at present fully operative. In this paper an overview of the instrument will be given and the status of the project will be reported.

Marisaldi, M.; Labanti, C.; Bulgarelli, A.; Celesti, E.; Di Cocco, G.; Gianotti, F.; Mauri, A.; Rossi, E.; Traci, A.; Trifoglio, M.

2004-02-01

212

Application of scintillating fiber gamma-ray detectors for medical imaging  

NASA Astrophysics Data System (ADS)

The recently developed plastic scintillating fiber technology started the development of a new generation of high spatial and time resolution gamma ray detectors for medical imaging, such as positron emission tomography (PET) and single photon emission computed tomography (SPECT). A scintillating fiber PET module consisting of two 5 X 5 X 2.5 cm(superscript 3) detector stacks made of parallel 1.0 mm diameter fiber, separated by 20 cm, each viewed by a Hamamatsu R2486 position sensitive photomultiplier was developed and tested. The time resolution of the coincidence system is 10 nsec. The spatial resolution and efficiency of this module turned out to be 2.3 mm (FWHM) and 2.0%, respectively, and independent of the location of the (superscript 22)Na testing source inside a sphere of 2 cm radius around the center of the two fiber stacks. The effect of gammas scattered in a 15 cm diameter water filled glass cylinder into which the (superscript 22)Na was immersed did not change the spatial resolution of the system.

Chaney, Roy C.; Fenyves, Ervin J.; Nelson, Gregory S.; Anderson, Jon A.; Antich, Peter P.; Atac, Muzaffer

1993-02-01

213

Toward 3D dosimetry of intensity modulated radiation therapy treatments with plastic scintillation detectors  

NASA Astrophysics Data System (ADS)

In this work, we present a novel two Dimensional Plastic Scintillation Detector (2D-PSD) array designed to measure dose distributions generated by high energy photon beams from medical linear accelerators. This study aim to demonstrate that the dose distribution in the irradiated volume is not modified by the presence of several hundred plastic scintillation detectors (PSDs). The 2D-PSD consists of 781 PSDs inserted in a plastic water slab. The dose distributions measured with the 2D-PSD were compared to calculations from a treatment planning system (Pinnacle3, Philips Medical Systems) and with measurements taken with an ionization chambers array (MatriXX Evolution, IBA Dosimetry). Furthermore, a clinical head and neck IMRT plan was delivered on the 2D-PSD. A good agreement is obtained between the measured and planned dose distributions. The results show that the 2D arrangement presented in this work is water equivalent and transparent to x-ray radiation. As a consequence, our design could be extended to multiple detection planes, opening the possibility for 3D dosimetry with PSDs.

Guillot, M.; Gingras, L.; Archambault, L.; Beddar, S.; Beaulieu, L.

2010-11-01

214

Setup of cryogenic front-end electronic systems for germanium detectors read-out  

Microsoft Academic Search

Front-end electronic devices for the read-out of ionizing radiation detectors must operate in many cases at cryogenic temperatures. In this work we focus in particular on front-end read-out systems for high-purity germanium (HPGe) detectors, which are usually operated at liquid nitrogen (LN) temperature. We analyze the strong effects that the changed characteristics of the electronic active and passive devices have

F. Zocca; A. Pullia; S. Riboldi; A. D'Andragora; C. Cattadori

2009-01-01

215

Scintillation detectors for operation in high magnetic fields: Recent developments based on arrays of avalanche microchannel photodiodes  

NASA Astrophysics Data System (ADS)

The development of scintillation detectors to be used in a high-magnetic-field environment requires novel photodetectors to substitute photomultiplier tubes (PMTs). Avalanche microchannel photodiodes (AMPDs) are competitive to PMTs in terms of gain and photon detection efficiency, and they are insensitive to magnetic fields. But the small active area of an AMPD (typically from 1 to 10mm) could restrict the field of applications for such a photosensor. In this work we demonstrate that the above restriction can be, to a certain extent, overcome by using AMPD arrays: based on an array of four (1×1mm) AMPDs we built scintillation detectors with promising characteristics.

Scheuermann, R.; Stoykov, A.; Renker, D.; Sadygov, Z.; Mehtieva, R.; Dovlatov, A.; Zhuk, V.

2007-10-01

216

Response characterization for an EJ315 deuterated organic-liquid scintillation detector for neutron spectroscopy  

NASA Astrophysics Data System (ADS)

Organic liquid scintillation detectors have shown promise as neutron detectors for characterizing special nuclear materials in various arms-control applications. Deuterated liquids, such as EJ315, are attractive for spectroscopy applications because the backward-peaked n-d scattering results in enhanced coupling between incident neutron energy and resulting pulse height. This will likely allow better spectrum unfolding. In this work, we present a measured neutron response matrix for a three-by-two-in. cylindrical EJ315 detector, and compare to the hydrogen-based liquid EJ309 in an otherwise identical assembly. We also present measured light-output relations for both detectors. A continuous-spectrum neutron source, obtained with the bombardment of 11B with 5.5-MeV deuterons at the tandem Van de Graaff accelerator at the University of Notre Dame, was used for the measurement. Detected neutrons were sorted via time of flight into 100-keV energy groups, over the energy range from 0.5 to 15 MeV. The resulting response matrix represents a detailed characterization of pulse-height response to neutrons over that energy range. To the authors' knowledge, a measured response matrix and light-output relation for EJ315 have not been reported, and published characterizations of the similar NE230 are of less detail over this energy range. Matrix-condition analysis indicates an advantage for EJ315 over EJ309 in the number of independent parameters available in inversion procedures.

Lawrence, Chris C.; Enqvist, Andreas; Flaska, Marek; Pozzi, Sara A.; Howard, A. M.; Kolata, J. J.; Becchetti, F. D.

2013-11-01

217

Short-baseline neutrino oscillation waves in ultra-large liquid scintillator detectors  

NASA Astrophysics Data System (ADS)

Powerful new multi-kiloton liquid scintillator neutrino detectors, including NO?A and, possibly, LENA, will come on-line within the next decade. When coupled with a modest-power decay-at-rest (DAR) neutrino source at short-baseline, these detectors can decisively address signals for neutrino oscillations at high ?m2. Along the greater than 50 m length of the detector, the characteristic oscillation wave will be apparent, providing powerful verification of the oscillation phenomenon. LENA can simultaneously perform ?? ? ?e appearance and ?e ? ?e disappearance searches while NO?A is likely limited to ?e disappearance. For the appearance channel, a LENA-like detector could test the LSND and MiniBooNE signal regions at >5 ? with a fiducial volume of 5 kt and a 10 kW neutrino source. The LENA and NO?A ?e disappearance sensitivities are complementary to the recent reactor anomaly indicating possible ?e disappearance and would cover this possible oscillation signal at ~3 ?.

Agarwalla, Sanjib Kumar; Conrad, J. M.; Shaevitz, M. H.

2011-12-01

218

Spatial and spectral gamma-ray response of plastic scintillators used in portal radiation detectors; comparison of measurements and simulations  

NASA Astrophysics Data System (ADS)

Portal radiation detectors are commonly used by steel industries in the probing and detection of radioactivity contamination in scrap metal. Furthermore, a large number of portal monitors are installed at the border crossings to prevent illegal radioactive material trafficking. These portal detectors typically consist of either PS (polystyrene) or PVT (polyvinyltoluene) plastic scintillating detectors. Through the electronic circuit of the detector, an energy region-of-interest window can be determined in order to focus on the detection of certain radionuclides. In this study, the spatial response of a portal's PS scintillator to a Cs-137 and a Co-60 source for various energy region-of-interest windows is presented. Furthermore, a number of measured spectra for different source positions on the surface of the scintillating detector are shown. The measured spatial response showed a quantitative and qualitative dependence on the energy window used each time. In addition, measured spectra showed energy shifts for different positions of the two sources on the detector surface. The aforementioned phenomena could not be adequately explained and modelled using gamma-particle transport Monte Carlo simulation tools, such as the MCNP4C2 code. In order to fully explain these phenomena, we performed optical simulations, modelling the transport of the light yield within the detector, using Gate v3.0.0 with Geant 4.8.0p01 of CERN. The results of those simulations are presented and compared to the measured ones.

Takoudis, G.; Xanthos, S.; Clouvas, A.; Antonopoulos-Domis, M.; Potiriadis, C.; Silva, J.

2009-02-01

219

Detection of the primary scintillation light from dense Ar, Kr and Xe with novel photosensitive gaseous detectors  

NASA Astrophysics Data System (ADS)

The detection of primary scintillation light in combination with the charge or secondary scintillation signals is an efficient technique in determining the events ``/t=0'' as well as particle/photon separation in large mass TPC detectors filled with noble gases and/or condensed noble gases. The aim of this work is to demonstrate that costly photo-multipliers could be replaced by cheap novel photosensitive gaseous detectors: wire counters, GEMs or glass capillary plates coupled with CsI photocathodes. We have performed systematic measurements with Ar, Kr and Xe gases at pressures in the range of 1-50atm as well as some preliminary measurements with liquid Xe and liquid Ar. With the gaseous detectors we have succeeded in detecting a scintillation light produced by 22keV X-rays with an efficiency close to 100%. We also detected the scintillation light produced by ?'s (5keV deposit energy) with an efficiency close to 25%. Successful detection of scintillation from 22keV X-rays open new experimental possibilities not only for nTOF and ICARUS experiments, but also in others, such as WIMP's search through nuclear recoil emission.

Periale, L.; Peskov, V.; Carlson, P.; Francke, T.; Pavlopoulos, P.; Picchi, P.; Pietropaolo, F.

2002-02-01

220

Simulation of optical configurations and signal processing methods in Anger-type neutron-position scintillation detector  

SciTech Connect

The spatial linearity and resolution of Anger-type neutron-position scintillation detectors are studied using a semi-empirical model. Detector optics with either an air gap or optical grease between the scintillator and the dispersive light guide are considered. Three signal processing methods which truncate signals from PMT's distant from the scintillation are compared with the linear resistive weighting method. Air gap optics yields a 15% improvement in spatial resolution and 50% reduction in differential and integral nonlinearity relative to grease coupled optics, using linear processing. Using signal truncation instead of linear processing improves the resolution 15-20% for the air gap and 20-30% for the grease coupling case. Thus, the initial discrepancy in the resolution between the two optics nearly vanished, however the linearity of the grease coupled system is still significantly poorer.

Roche, C.T.; Strauss, M.G.; Brenner, R.

1984-01-01

221

Neutron detection and multiplicity counting using a boron-loaded plastic scintillator\\/bismuth germanate phoswich detector array  

Microsoft Academic Search

Neutron detection and multiplicity counting has been investigated using a boron-loaded plastic scintillator\\/bismuth germanate phoswich detector array. Boron-loaded plastic combines neutron moderation (H) and detection (¹°B) at the molecular level, thereby physically coupling increasing detection efficiency and decreasing die-away time with detector volume. Both of these characteristics address a fundamental limitation of thermal-neutron multiplicity counters, where ³He proportional counters are

1998-01-01

222

Neutron detection and multiplicity counting using a boron-loaded plastic scintillator\\/bismuth germanate phoswich detector array  

Microsoft Academic Search

Neutron detection and multiplicity counting has been investigated using a boron-loaded plastic scintillator\\/bismuth germanate phoswich detector array. Boron-loaded plastic combines neutron moderation (H) and detection (10B) at the molecular level, thereby physically coupling increasing detection efficiency and decreasing die-away time with detector volume. Both of these characteristics address a fundamental limitation of thermal-neutron multiplicity counters, where 3He proportional counters are

Michael Conrad Miller

1997-01-01

223

Detection of light flashes in a CsI (T1) scintillator with the aid of a semiconductor detector  

Microsoft Academic Search

The drawbacks of photomultipliers (PM) used in scintillation spectrometers (sensitivity to magnetic fields, thermal and temporal instability, need of a high-voltage power supply, and large dimensions) have repeatedly stimulated attempts to replace these devices with photodiodes (PD) or semiconductor detectors (SD) of nuclear radiation. The combined detector described is based on CsI(T1) and a DKPs-25-1 commercial semiconductor device. The energy

Y. G. Zdensenko; B. N. Kropivyanskii

1985-01-01

224

Real-time scintillation array dosimetry for radiotherapy: The advantages of photomultiplier detectors  

SciTech Connect

Purpose: In this paper, a photomultiplier tube (PMT) array dosimetry system has been developed and tested for the real-time readout of multiple scintillation signals from fiber optic dosimeters. It provides array dosimetry with the advantages in sensitivity provided by a PMT, but without the need for a separate PMT for each detector element. Methods: The PMT array system consisted of a multianode PMT, a multichannel data acquisition system, housing and optic fiber connections suitable for clinical use. The reproducibility, channel uniformity, channel crosstalk, acquisition speed, and sensitivity of the PMT array were quantified using a constant light source. Its performance was compared to other readout systems used in scintillation dosimetry. An in vivo HDR brachytherapy treatment was used as an example of a clinical application of the dosimetry system to the measurement of dose at multiple sites in the rectum. The PMT array system was also tested in the pulsed beam of a linear accelerator to test its response speed and its application with two separate methods of Cerenkov background removal. Results: The PMT array dosimetry system was highly reproducible with a measurement uncertainty of 0.13% for a 10 s acquisition period. Optical crosstalk between neighboring channels was accounted for by omitting every second channel. A mathematical procedure was used to account for the crosstalk in next-neighbor channels. The speed and sensitivity of the PMT array system were found be superior to CCD cameras, allowing for measurement of more rapid changes in dose rate. This was further demonstrated by measuring the dose delivered by individual photon pulses of a linear accelerator beam. Conclusions: The PMT array system has advantages over CCD camera-based systems for the readout of scintillation light. It provided a more sensitive, more accurate, and faster response to meet the demands of future developments in treatment delivery.

Liu, Paul Z. Y.; Suchowerska, Natalka; Abolfathi, Peter; McKenzie, David R. [School of Physics, University of Sydney, New South Wales 2006, Australia and Department of Radiation Oncology, Royal Prince Alfred Hospital, Camperdown, New South Wales 2050 (Australia); School of Physics, University of Sydney, New South Wales 2006 (Australia)

2012-04-15

225

Experimental Evaluation of a Thermopile Detector With SU8 Membrane in a Carbon Dioxide Meter Setup  

Microsoft Academic Search

Continuous control of the carbon dioxide levels in the ventilation systems in office buildings and public schools has been shown to increase productivity and save money. However, these measurement systems require further developments in order to be more cost effective. This paper presents an evaluation of an Al\\/Bi thermopile detector with a 4 mum thin SiO2\\/SU-8 membrane in a CO2

Claes G. Mattsson; GÖran Thungstrom; Henrik Rodjegard; Kent Bertilsson; Hans-Erik Nilsson; Hans Martin

2009-01-01

226

Detector for Gamma-Radiation-Imaging Devices: Cooled bismuth germanate crystal has good scintillation and mechanical properties.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. A cooled bismuth germanate crystal is an effective gamma-radiation detector for scintillation cameras. This material, Bi4Ge3O12 (referred to as BGO), is denser and h...

1981-01-01

227

Fiber optic thermal/fast neutron and gamma ray scintillation detector  

DOEpatents

A system for detecting fissile and fissionable material originating external to the system includes: a .sup.6Li loaded glass fiber scintillator for detecting thermal neutrons, x-rays and gamma rays; a fast scintillator for detecting fast neutrons, x-rays and gamma rays, the fast scintillator conjoined with the glass fiber scintillator such that the fast scintillator moderates fast neutrons prior to their detection as thermal neutrons by the glass fiber scintillator; and a coincidence detection system for processing the time distributions of arriving signals from the scintillators.

Neal, John S. (Knoxville, TN); Mihalczo, John T (Oak Ridge, TN)

2007-10-30

228

Energy resolution of scintillation detectors readout with large area avalanche photodiodes and photomultipliers  

SciTech Connect

The energy resolution of small NaI(Tl), CsI(Tl), BGO, GSO, YAP and LSO crystals has been studied using 16 mm diameter large area avalanche photodiodes (LAAPD) and a 52 mm diameter photomultiplier. The best result of 4.8% for 662 keV {gamma}-rays from a {sup 137}Cs source was obtained with a 9 mm in diameter by 9 mm high CsI(Tl) scintillator coupled to an LAAPD. Measuring the number of primary electron-hole pairs produced in the LAAPD and photoelectrons in the photomultiplier, as well as the noise contribution of the LAAPD, allowed a quantitative discussion of the results. The energy resolutions measured with LAAPDs are comparable to, or significantly better (at certain emission wavelengths) than, those obtained with the photomultiplier. At energies above 100 keV the energy resolution measured with the majority of crystals and the LAAPD was weakly affected by the photodiode noise contribution. The advantages and limitations of LAAPDs in energy spectrometry with scintillation detectors are also discussed.

Moszynski, M.; Wolski, D. [Soltan Inst. for Nuclear Studies, Swierk-Otwock (Poland); Kapusta, M. [Soltan Inst. for Nuclear Studies, Swierk-Otwock (Poland)]|[Univ. of Warsaw (Poland). Inst. of Experimental Physics; Szawlowski, M. [Advanced Photonix, Inc., Camarillo, CA (United States); Klamra, W. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Physics

1998-06-01

229

Development of Lanthanum Bromide and Lanthanum Chloride Scintillator Detectors for Hard X-ray Astronomy  

NASA Astrophysics Data System (ADS)

Advanced scintillator materials such as LaBr3:Ce and LaCl3:Ce hold great promise for future hard X-ray and gamma-ray astrophysics missions due to their high density, high light output, good linearity, and fast decay times. Of particular importance for future space-based imaging instruments, such as coded-aperture telescopes, are the precise spatial location of individual gamma-ray interactions and the susceptibility of the material to radiation damage. We have investigated the position and energy resolution achievable within LaBr3:Ce and LaCl3:Ce crystals (both monolithic and pixellated) using a variety of readout techniques, including position-sensitive photomultiplier tubes, multi-anode photomultiplier tubes, and orthogonal layers of wavelength-shifting fibers. We have also exposed LaBr3:Ce and LaCl3:Ce detectors to high-energy proton irradiation in order to study any radiation damage and activation. We present the results of these tests and discuss the applicability of such advanced scintillators to future high-energy imaging astrophysics missions.

Bloser, Peter F.; Budden, B. S.; Case, G. L.; Cherry, M. L.; Macri, J. R.; McConnell, M. L.; Ryan, J. M.

2006-09-01

230

Toward a Real-Time In Vivo Dosimetry System Using Plastic Scintillation Detectors  

SciTech Connect

Purpose: In the present study, we have presented and validated a plastic scintillation detector (PSD) system designed for real-time multiprobe in vivo measurements. Methods and Materials: The PSDs were built with a dose-sensitive volume of 0.4 mm{sup 3}. The PSDs were assembled into modular detector patches, each containing five closely packed PSDs. Continuous dose readings were performed every 150 ms, with a gap between consecutive readings of <0.3 ms. We first studied the effect of electron multiplication. We then assessed system performance in acrylic and anthropomorphic pelvic phantoms. Results: The PSDs were compatible with clinical rectal balloons and were easily inserted into the anthropomorphic phantom. With an electron multiplication average gain factor of 40, a twofold increase in the signal/noise ratio was observed, making near real-time dosimetry feasible. Under calibration conditions, the PSDs agreed with the ion chamber measurements to 0.08%. Precision, evaluated as a function of the total dose delivered, ranged from 2.3% at 2 cGy to 0.4% at 200 cGy. Conclusion: Real-time PSD measurements are highly accurate and precise. These PSDs can be mounted onto rectal balloons, transforming these clinical devices into in vivo dose detectors without modifying current clinical practice. Real-time monitoring of the dose delivered near the rectum during prostate radiotherapy should help radiation oncologists protect this sensitive normal structure.

Archambault, Louis; Briere, Tina M.; Poenisch, Falk [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Beaulieu, Luc [Departement de Radio-oncologie, Centre Hospitalier Universitaire de Quebec, Quebec, QC (Canada); Kuban, Deborah A.; Lee, Andrew [Department of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States); Beddar, Sam, E-mail: beddar@mdanderson.or [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)

2010-09-01

231

A practical method for depth of interaction determination in monolithic scintillator PET detectors.  

PubMed

Several new methods for determining the depth of interaction (DOI) of annihilation photons in monolithic scintillator detectors with single-sided, multi-pixel readout are investigated. The aim is to develop a DOI decoding method that allows for practical implementation in a positron emission tomography system. Specifically, calibration data, obtained with perpendicularly incident gamma photons only, are being used. Furthermore, neither detector modifications nor a priori knowledge of the light transport and/or signal variances is required. For this purpose, a clustering approach is utilized in combination with different parameters correlated with the DOI, such as the degree of similarity to a set of reference light distributions, the measured intensity on the sensor pixel(s) closest to the interaction position and the peak intensity of the measured light distribution. The proposed methods were tested experimentally on a detector comprised of a 20 mm × 20 mm × 12 mm polished LYSO:Ce crystal coupled to a 4 × 4 multi-anode photomultiplier. The method based on the linearly interpolated measured intensities on the sensor pixels closest to the estimated (x, y)-coordinate outperformed the other methods, yielding DOI resolutions between ?1 and ?4.5 mm FWHM depending on the DOI, the (x, y) resolution and the amount of reference data used. PMID:21693789

van Dam, Herman T; Seifert, Stefan; Vinke, Ruud; Dendooven, Peter; Löhner, Herbert; Beekman, Freek J; Schaart, Dennis R

2011-06-21

232

Simulation studies of a scintillating fiber tracker for the SDC detector  

NASA Astrophysics Data System (ADS)

Six design options for a scintillating fiber inner tracker for the SDC detector operating at the Superconducting Super Collider (SSC) are simulated. Concentric cylindrical configurations of axial fiber superlayers, ranging from four to six in number, are considered. Tracks from events generated by Pythia 4.8 at rates up to ten times design luminosity are swum through the tracker. Algorithms for reconstructing tracks of physics interest with pT > 10 GeV/c among a background of low pT tracks are described. The optimum configuration found permits level 1 triggering up to ? = 2.3 at ten times design luminosity. Inclusion of additional stereo fibers in this configuration permits level 2 stereo reconstruction up to eight times design luminosity.

Hertzler, J.; Lewis, R. A.; Mitchell, G. S.; Moore, R. S.; Smith, G. A.; Walsh, T. F.

1994-05-01

233

Discriminating Neutron-Gamma Waveforms from Novel Scintillation Detectors using Digital Pulse Processing  

NASA Astrophysics Data System (ADS)

In this research, we report the results of neutron-? pulse shape discrimination studies performed with digital signal processing techniques. Two novel scintillator crystals, Cs2LiLaBr6 (CLLB) and Cs2LiYCl6 (CLYC), (provided by Radiation Monitoring Devices Inc.), which have different pulse shapes for neutron and ?-ray detection, were used to detect neutrons and ?-rays from a PuBe source enclosed in paraffin. Following digitization of the pulse waveforms with a 1 GHz Lecroy Digital Oscilloscope, a pulse shape discrimination algorithm was explored through custom C++ programs integrated within the ROOT analysis software developed at CERN. The selection of integration windows was optimized to provide the greatest separation between the two signals. The latest results for the CLYC and CLLB crystal will be presented and the neutron-? discrimination capabilities of the two detectors will be compared.

Harrington, T.; Lakshmi, S.; Chowdhury, P.; Glodo, J.; Shah, K.

2011-04-01

234

Energy resolution of small scintillation detectors with SiPM light readout  

NASA Astrophysics Data System (ADS)

The development of silicon photomultipliers (SiPMs) with a large number of APD cells and improved linearity of the pulse height response prompted interest in their application to gamma spectrometry with scintillators. Hamamatsu MPPC sensors equipped with 3600 and 14400 APD cells were chosen in our study because of their well pronounced single photoelectron spectra, which allowed us to precisely measure the photoelectron numbers (PHE) or fired APD cells and then to discuss, in a quantitative manner, the obtainable energy resolution. The studied detectors were first characterized in direct detection of laser light pulses and then in gamma spectroscopy with LFS and CsI:Tl crystals. In the study with the laser light pulses the linearity of the MPPC response versus a light pulse intensity monitored with PMT was measured. Two different methods were used for an evaluation of the MPPC response expressed in the number of photoelectrons (PHE) generated by light illumination. The direct method (PHEdir), based on the comparison of the light peak position to that of the single photoelectron peak, determined the upper limit of the PHE. The lower limit of the PHE was derived from an analysis of the measured pulse height resolution under the assumption of Poisson statistics and MPPC excess noise factor (ENF) of 1. Furthermore, the ENF of the MPPC is discussed with respect to the contributions of device dead time, optical cross-talk and after-pulses to the results obtained. In the scintillation tests, measurements of energy resolution and non-proportionality of the light yield were performed with LFS and CsI:Tl crystals, and both types of 3 × 3 mm MPPC detectors were used for light readout. The results are discussed in a quantitative manner based on the measured PHE.

Grodzicka, M.; Moszy?ski, M.; Szcz??niak, T.; Kapusta, M.; Szaw?owski, M.; Wolski, D.

2013-02-01

235

Characterization of indirect X-ray imaging detector based on nanocrystalline gadolinium oxide scintillators for high-resolution imaging application  

NASA Astrophysics Data System (ADS)

Nanocrystalline Gd2O3:Eu scintillating powders were successfully synthesized through a co-precipitation process for X-ray imaging detector applications. In this work, as-synthesized sample was further calcinated at different temperature, time with 1-10 h and doped-Eu3+ concentration with 1-10 mol% in the electrical furnace. The characterization such as the crystal structures and microstructure of Gd2O3:Eu scintillator were measured by XRD and SEM experiment. The phase transition from cubic to monoclinic structure was observed at 1300 °C calcination temperature. Dominant emission peak of sample with cubic structure was appeared at 611 nm under 266 nm UV light excitation. After scintillation properties of synthesized Gd2O3:Eu scintillator were investigated, Gd2O3:Eu scintillating films with different thickness was fabricated onto glass substrate by a screen printing method. And then X-ray imaging performance in terms of the light response to X-ray exposure dose, signal-to-noise ratio (SNR) and spatial resolution were measured by combining the fabricated Gd2O3:Eu screen films with a lens-coupled CCD imaging detector under radiographic system conditions.

Seo, Chang-Woo; Kyung Cha, Bo; Jeon, Sungchae; Kyung Kim, Ryun; Huh, Young

2013-01-01

236

A Comparison of Performance Between Organic Scintillation Crystals and Moderated (3)He-Based Detectors for Fission Neutron Detection  

SciTech Connect

Direct detection of fast neutrons using organic scintillators is one alternative to moderated thermal neutron detectors deployed to detect fission neutrons - a relevant question in light of dwindling {sup 3}He supplies. Recent developments in materials science have demonstrated the capability to grow larger crystals in reasonable times. In light of these developments, this study compares the relative performance of a {sup 3}He-based neutron module from a commercially available portal monitor with a theoretical organic scintillator of similar overall size. Stilbene serves as a benchmark with its performance estimated from a combination of energy deposition modeled by radiation transport calculations and an assumption of the lowest neutron energy at which pulse shape discrimination can effectively separate neutron and gamma-ray events. Before intrinsic detection efficiencies on par with moderated detector systems can be achieved, the results point to the need for further advances including significant increases in detector size, especially thickness, and/or lower pulse shape discrimination thresholds.

Robinson, Sharon M [ORNL; Newby, Robert Jason [ORNL; Runkle, Robert Charles [ORNL

2011-01-01

237

A comparison of performance between organic scintillation crystals and moderated 3He-based detectors for fission neutron detection  

NASA Astrophysics Data System (ADS)

Direct detection of fast neutrons using organic scintillators is one alternative to moderated thermal neutron detectors deployed to detect fission neutrons—a relevant question in light of dwindling 3He supplies. Recent developments in materials science have demonstrated the capability to grow larger crystals in reasonable times. In light of these developments, this study compares the relative performance of a 3He-based neutron module from a commercially available portal monitor with a theoretical organic scintillator of similar overall size. Stilbene serves as a benchmark with its performance estimated from a combination of energy deposition modeled by radiation transport calculations and an assumption of the lowest neutron energy at which pulse shape discrimination can effectively separate neutron and gamma-ray events. Before intrinsic detection efficiencies on par with moderated detector systems can be achieved, the results point to the need for further advances including significant increases in detector size, especially thickness, and/or lower pulse shape discrimination thresholds.

Robinson, S. M.; Runkle, R. C.; Newby, R. J.

2011-10-01

238

A gated liquid-scintillator-based neutron detector for fast-ignitor experiments and down-scattered neutron measurements  

SciTech Connect

The detection of neutrons in fast-ignitor experiments or down-scattered neutrons in inertial fusion experiments is very challenging since it requires the neutron detection system to recover within 10-100 ns from a high background orders of magnitude stronger than the signal of interest. The background is either the hard x-ray emission from short-pulse laser target interactions for the fast-ignitor experiments or the primary neutron signal for the down-scattered neutrons. A liquid-scintillator detector has been developed using a gated photomultiplier that suppresses the background signal and eliminates the afterglow present in conventional plastic scintillators.

Stoeckl, C.; Cruz, M.; Glebov, V. Yu.; Knauer, J. P.; Marshall, K.; Mileham, C.; Sangster, T. C.; Theobald, W. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States); Lauck, R. [Physikalisch Technische Bundesanstalt, D-38116 Braunschweig (Germany)

2010-10-15

239

High count rate ?-ray spectroscopy with LaBr3:Ce scintillation detectors  

NASA Astrophysics Data System (ADS)

The applicability of LaBr3:Ce detectors for high count rate ?-ray spectroscopy is investigated. A 3 in.×3 in. LaBr3:Ce detector is used in a test setup with radioactive sources to study the dependence of energy resolution and photo peak efficiency on the overall count rate in the detector. Digitized traces were recorded using a 500 MHz FADC and analysed with digital signal processing methods. Good performance is obtained using standard techniques up to about 500 kHz counting rate. A pile-up correction method is applied to the data in order to further improve the capabilities at even higher rates with a focus on recovering the losses in efficiency due to signal pile-up. It is shown that ?-ray spectroscopy can be performed with only moderate lossen in efficiency and high resolution at count rates even above 1 MHz and that the performance can be enhanced in the region between 500 kHz and 10 MHz by using the applied pile-up correction techniques.

Löher, B.; Savran, D.; Fiori, E.; Miklavec, M.; Pietralla, N.; Vencelj, M.

2012-09-01

240

Neutron-induced 235U fission spectrum measurements using liquid organic scintillation detectors  

NASA Astrophysics Data System (ADS)

Measurements have been performed at Los Alamos Neutron Science Center to acquire neutron fission spectra of 235U in the energy range between 0.5 and 10 MeV. These new data complement the currently available experimental data, which are not well known in the energy range below 1 and above 5 MeV. Organic liquid scintillation detectors (EJ-309s) were used together with a digital data-acquisition system. The EJ-309 detectors show excellent pulse shape discrimination capabilities and this is vital for identifying only neutron pulses and rejecting ?-ray pulses. The measurement data show the dependence of average fission neutron energy as a function of the inducing neutron energy. The data agree well with previously published measurements and Watt spectra fits for energies up to tens of MeV. At high fission-inducing neutron energies the spectrum deviates from Watt-spectra fits. The increased energy deposited in higher energy neutron-induced fissions does not significantly increase emitted fission neutron energies for up to 10 MeV. A significant decrease in neutron energy around second-chance fission cannot be observed beyond the current measurement uncertainties.

Enqvist, Andreas; Wieger, Brian M.; Huang, Lu; Flaska, Marek; Pozzi, Sara A.; Haight, Robert C.; Lee, Hye Young; Kwan, Elaine; Wu, Ching Yen

2012-12-01

241

Optimization of decay kinetics of YAG:Ce single crystal scintillators for S(T)EM electron detectors  

NASA Astrophysics Data System (ADS)

To enhance the detective quantum efficiency (DQE) of scintillation electron detectors for scanning electron microscopes or scanning transmission electron microscopes (S(T)EM), the cathodoluminescence (CL) decay kinetics of YAG:Ce single crystal scintillators is studied in this paper. Some possibilities for reductions of decay time and afterglow of the mentioned scintillators are presented. The pulse mode utilizing a blanking system and 10 keV electrons for the excitation and a sampling oscilloscope for the CL detection were used for the measurement of decay characteristics. The CL decay characteristics of YAG:Ce single crystals of different Ce concentrations, pulled by the Czochralski method and cleaned and annealed under specific conditions, were measured in dependence on excitation pulse duration and on the specimen temperature. To interpret the presented results, a kinetic model of cathodoluminescence of the YAG:Ce single crystals was created. The effects of quenching impurities and of defect centers in YAG:Ce were specified.

Schauer, Petr

2011-11-01

242

Calculation of the light pulse distributions induced by fast neutrons in organic scintillation detectors  

NASA Astrophysics Data System (ADS)

We develop a fully analytic and self-contained description of the amplitude distribution of light pulses in an organic scintillation detector due to a monoenergetic source of fast neutrons. To this end, two classes of problems have to be handled. One is a formula for the light pulse amplitude distribution for the complete life history of neutrons slowing down in a mixture of hydrogen and carbon as a statistical average over all collision sequences that can occur, accounting also for neutron leakage. A complete solution is given in terms of a non-recursive convolution integral expansion with respect to the various possible collision histories. These latter are dependent on the collision probabilities of neutrons of a given energy. The second is the calculation of this collision probability from analytical expressions for the geometry of the detector, in the present case a right cylinder. This quantity was taken from Monte Carlo simulations in previous work. Recursive formulae are derived for the probabilities of arbitrary collision sequences, and quantitative results are given for up to five consecutive collisions of all combinations. These probabilities can be used to determine how to truncate the non-recursive expansion of the full light amplitude distribution in quantitative work. The calculational method serves to lend insight and understanding into the structure of the pulse height spectra, as well as it provides a computationally cheap method of generating a large number of such spectra for various detector compositions, sizes and neutron energies, for the development and test of new spectrum unfolding techniques.

Enqvist, Andreas; Pázsit, Imre

2010-06-01

243

Dosimetric performance and array assessment of plastic scintillation detectors for stereotactic radiosurgery quality assurance  

SciTech Connect

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. 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.

Gagnon, Jean-Christophe; Theriault, Dany; Guillot, Mathieu; Archambault, Louis; Beddar, Sam; Gingras, Luc; Beaulieu, Luc [Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec G1R 2J6 (Canada); Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec G1R 2J6 (Canada); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec G1R 2J6 (Canada); Department of Radiation Physics, Unit 94, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec G1R 2J6 (Canada)

2012-01-15

244

X-ray radiation detectors of ``scintillator-photoreceiving device type'' for industrial digital radiography with improved spatial resolution  

NASA Astrophysics Data System (ADS)

Main types of photoreceivers used in X-ray digital radiography systems are luminescent screens that transfer the optical image onto charge collection instruments, which require cooling, and semiconductor silicon detectors, which limit the contrast sensitivity. We have developed and produced X-ray radiation detectors of ``scintillator-photoreceiving device'' (S-PRD) type, which are integrally located on the inverse side of the photodiode (PD). The receiving-converting circuit (RCC) is designed for data conversion into digital form and their input into PC. Software is provided for RCC control and image visualization. Main advantages of these detectors are high industrial resolution (3-5 line pairs per mm), detecting activity up to 20?m, controlled sensitivity, low weight and small size, imaging low (0.1-0.3mrad) object dose in real time. In this work, main characteristics of 32-, 64- and 1024-channel detectors of S-PRD type were studied and compared for X-ray sensitivity with S-PD detectors. Images of the tested objects have been obtained. Recommendations are given on the use of different scintillation materials, depending upon the purpose of a digital radiographic system. The detectors operate in a broad energy range of ionizing radiation, hence the size of the controlled object is not limited. The system is sufficiently powerful to ensure frontal (through two walls) observation of pipelines with wall thickness up to 10cm.

Ryzhykov, V. D.; Lysetska, O. K.; Opolonin, O. D.; Kozin, D. N.

2003-06-01

245

Light-output response of the plastic scintillator for the Mars Science Laboratory (MSL) Radiation Assessment Detector (RAD)  

NASA Astrophysics Data System (ADS)

The Radiation Assessment Detector (RAD) onboard NASA's Mars Science Laboratory (MSL) rover mission has been designed to detect a wide range of particle types (charged and neutral) and energies on the Mars surface. The BC432m plastic scintillator coupled to PIN photodiodes has been used as a neutron detector as well as an anticoincidence shield for the RAD instrument. We present an experimental study of the non-linear light-output response of the BC432m for protons and neutrons beams. The experimental results have been compared to the parametric formula based on the theoretical work of Birks and Chou. Furthermore, a comparison between the quenching effect found in the BC432m and in other inorganic scintillators (CsI:Tl) used in the RAD instrument has been performed.

Martin, C.; Boehm, E.; Kortmann, O.; Boettcher, S.; Wimmer-Schweingruber, R. F.; Burmeister, S.; Ehresmann, B.; Hassler, D. M.; Zeitlin, C.; Posner, A.; Neal, K.; Rafkin, S.; Weigle, E.; Reitz, G.

2008-12-01

246

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

247

Three-dimensional array of scintillation crystals with proper reflector arrangement for a depth of interaction detector  

Microsoft Academic Search

A 16×16×4 multicrystal detector module to acquire depth of interaction (DOI) information is proposed for a next generation positron emission tomography scanner that realizes high resolution and high sensitivity. The scintillation crystal array is coupled with a 256ch flat panel position sensitive photomultiplier tube (256ch FP-PMT) having large opening area. One unit consists of 2×2×4 crystal elements. The units are

Narimichi Orita; Hideo Murayama; Hideyuki Kawai; Naoko Inadama; Tomoaki Tsuda

2003-01-01

248

Development of Compact Wide-Angle Imaging Detector for MeV Gamma-Rays using Stacked BGO Scintillator Rods  

Microsoft Academic Search

We are developing a compact wide-angle imaging detector for MeV gamma-rays using stacked BGO scintillator rods to apply to neutron induced prompt gamma-ray analysis (NPGA), which is one of the promising methods for non-destructive detection of hidden explosives by measuring characteristic gamma-rays produced from chemical elements. The gamma-ray imaging in NPGA applications is also necessary to locate them and improve

Kenichi Watanabe; Shinji Mihoya; J. Kawarabayashi; T. Iguchi

2006-01-01

249

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

Microsoft Academic Search

By using a pixelized Nal(Tl) crystal array coupled to a R2486 PSPMT, the characteristics of the array and of a single pixel, such as the light output, energy resolution, peak-to-valley ratio (P\\/V) and imaging performance of the detector were studied. The pixel size of the NaI(TI) scintillation pixel array is 2 mm×2 mm×5 mm. There are in total 484 pixels

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

2009-01-01

250

Spectral method for the correction of the Cerenkov light effect in plastic scintillation detectors: A comparison study of calibration procedures and validation in Cerenkov light-dominated situations  

SciTech Connect

Purpose: The purposes of this work were: (1) To determine if a spectral method can accurately correct the Cerenkov light effect in plastic scintillation detectors (PSDs) for situations where the Cerenkov light is dominant over the scintillation light and (2) to develop a procedural guideline for accurately determining the calibration factors of PSDs. Methods: The authors demonstrate, by using the equations of the spectral method, that the condition for accurately correcting the effect of Cerenkov light is that the ratio of the two calibration factors must be equal to the ratio of the Cerenkov light measured within the two different spectral regions used for analysis. Based on this proof, the authors propose two new procedures to determine the calibration factors of PSDs, which were designed to respect this condition. A PSD that consists of a cylindrical polystyrene scintillating fiber (1.6 mm{sup 3}) coupled to a plastic optical fiber was calibrated by using these new procedures and the two reference procedures described in the literature. To validate the extracted calibration factors, relative dose profiles and output factors for a 6 MV photon beam from a medical linac were measured with the PSD and an ionization chamber. Emphasis was placed on situations where the Cerenkov light is dominant over the scintillation light and on situations dissimilar to the calibration conditions. Results: The authors found that the accuracy of the spectral method depends on the procedure used to determine the calibration factors of the PSD and on the attenuation properties of the optical fiber used. The results from the relative dose profile measurements showed that the spectral method can correct the Cerenkov light effect with an accuracy level of 1%. The results obtained also indicate that PSDs measure output factors that are lower than those measured with ionization chambers for square field sizes larger than 25x25 cm{sup 2}, in general agreement with previously published Monte Carlo results. Conclusions: The authors conclude that the spectral method can be used to accurately correct the Cerenkov light effect in PSDs. The authors confirmed the importance of maximizing the difference of Cerenkov light production between calibration measurements. The authors also found that the attenuation of the optical fiber, which is assumed to be constant in the original formulation of the spectral method, may cause a variation of the calibration factors in some experimental setups.

Guillot, Mathieu; Gingras, Luc; Archambault, Louis; Beddar, Sam; Beaulieu, Luc [Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec, Quebec G1R 2J6 (Canada); Department of Radiation Physics, Unit 94, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, Texas 77030 (United States); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec, Quebec G1R 2J6 (Canada)

2011-04-15

251

Detection of light flashes in a CsI (T1) scintillator with the aid of a semiconductor detector  

SciTech Connect

The drawbacks of photomultipliers (PM) used in scintillation spectrometers (sensitivity to magnetic fields, thermal and temporal instability, need of a high-voltage power supply, and large dimensions) have repeatedly stimulated attempts to replace these devices with photodiodes (PD) or semiconductor detectors (SD) of nuclear radiation. The combined detector described is based on CsI(T1) and a DKPs-25-1 commercial semiconductor device. The energy resolution of the system is 5.2% with respect to alpha particles of /sup 241/Am source (5.486 MeV).

Zdensenko, Y.G.; Kropivyanskii, B.N.

1985-07-01

252

Radiopurity of a CeBr3 crystal used as scintillation detector  

NASA Astrophysics Data System (ADS)

Cerium bromide (CeBr3) has recently been shown to exhibit several properties making it a suitable material as a scintillation detector in nuclear physics applications. The intrinsic activity of gamma-ray emitting radionuclides in a 38.1 mm×38.1 mm (diameter×height) crystal of CeBr3 was investigated. The measurements were carried out in the HADES underground laboratory located 225 m underground. Two primordial radionuclides were detected; 227Ac (and its daughters) with massic activity of 0.30±0.02 Bq/kg and 138La with massic activity of 7.4±1.0 mBq/kg. Two activation products were also detected; 139Ce and 82Br. Their massic activities (assuming a homogeneous distribution in the crystal) just before taking the CeBr3 crystal underground were 4.3±0.3 mBq/kg and 18±4 mBq/kg correspondingly. None of the other common primordial radionuclides (40K, 226Ra, 228Ra, 228Th, and 235U) were detected and their detection limits were below 2 mBq/kg except for 238U for which the upper limit was 135 mBq/kg and 210Pb with an upper limit of 600 mBq/kg.

Lutter, Guillaume; Hult, Mikael; Billnert, Robert; Oberstedt, Andreas; Oberstedt, Stephan; Andreotti, Erica; Marissens, Gerd; Rosengård, Ulf; Tzika, Faidra

2013-03-01

253

Extraction of depth-dependent perturbation factors for silicon diodes using a plastic scintillation detector  

SciTech Connect

Purpose: This work presents the experimental extraction of the perturbation factor in megavoltage electron beams for three models of silicon diodes (IBA Dosimetry, EFD and SFD, and the PTW 60012 unshielded) using a plastic scintillation detector (PSD). Methods: The authors used a single scanning PSD mounted on a high-precision scanning tank to measure depth-dose curves in 6-, 12-, and 18-MeV clinical electron beams. They also measured depth-dose curves using the IBA Dosimetry, EFD and SFD, and the PTW 60012 unshielded diodes. The authors used the depth-dose curves measured with the PSD as a perturbation-free reference to extract the perturbation factors of the diodes. Results: The authors found that the perturbation factors for the diodes increased substantially with depth, especially for low-energy electron beams. The experimental results show the same trend as published Monte Carlo simulation results for the EFD diode; however, the perturbations measured experimentally were greater. They found that using an effective point of measurement (EPOM) placed slightly away from the source reduced the variation of perturbation factors with depth and that the optimal EPOM appears to be energy dependent. Conclusions: The manufacturer recommended EPOM appears to be incorrect at low electron energy (6 MeV). In addition, the perturbation factors for diodes may be greater than predicted by Monte Carlo simulations.

Lacroix, Frederic; Guillot, Mathieu; McEwen, Malcolm; Gingras, Luc; Beaulieu, Luc [Departement de Radio-Oncologie, Centre hospitalier de l'Universite de Montreal (CHUM), 1560 Sherbrooke est, Montreal, Quebec H2L 4M1, Canada and Departement de Physique, Universite de Montreal, Pavillon Roger-Gaudry (D-428), 2900 Boul. Edouard-Montpetit, Montreal, Quebec H3T 1J4 (Canada); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec G1K 7P4, Quebec, Canada and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre hospitalier universitaire de Quebec (CHUQ), Quebec, Quebec G1R 2J6 (Canada); Ionizing Radiation Standards, Institute for National Measurement Standards, National Research Council (NRC), Ottawa, Ontario K1A 0R6 (Canada); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec G1K 7P4, Quebec, Canada and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre hospitalier universitaire de Quebec (CHUQ), Quebec, Quebec G1R 2J6 (Canada)

2011-10-15

254

Sub-200 ps CRT in monolithic scintillator PET detectors using digital SiPM arrays and maximum likelihood interaction time estimation  

NASA Astrophysics Data System (ADS)

Digital silicon photomultiplier (dSiPM) arrays have favorable characteristics for application in monolithic scintillator detectors for time-of-flight positron emission tomography (PET). To fully exploit these benefits, a maximum likelihood interaction time estimation (MLITE) method was developed to derive the time of interaction from the multiple time stamps obtained per scintillation event. MLITE was compared to several deterministic methods. Timing measurements were performed with monolithic scintillator detectors based on novel dSiPM arrays and LSO:Ce,0.2%Ca crystals of 16 × 16 × 10 mm3, 16 × 16 × 20 mm3, 24 × 24 × 10 mm3, and 24 × 24 × 20 mm3. The best coincidence resolving times (CRTs) for pairs of identical detectors were obtained with MLITE and measured 157 ps, 185 ps, 161 ps, and 184 ps full-width-at-half-maximum (FWHM), respectively. For comparison, a small reference detector, consisting of a 3 × 3 × 5 mm3 LSO:Ce,0.2%Ca crystal coupled to a single pixel of a dSiPM array, was measured to have a CRT as low as 120 ps FWHM. The results of this work indicate that the influence of the optical transport of the scintillation photons on the timing performance of monolithic scintillator detectors can at least partially be corrected for by utilizing the information contained in the spatio-temporal distribution of the collection of time stamps registered per scintillation event.

van Dam, Herman T.; Borghi, Giacomo; Seifert, Stefan; Schaart, Dennis R.

2013-05-01

255

Lead carbonate scintillator materials  

DOEpatents

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.

Derenzo, Stephen E. (Pinole, CA); Moses, William W. (Berkeley, CA)

1991-01-01

256

Light output analyzes of scintillator crystal pins and array for PET detector modules  

Microsoft Academic Search

A new Zemax model has been developed that is capable to predict reliably the light output of scintillator crystal pins of different configurations, i.e. geometry, surface finish and reflector material. Model parameters are measured wavelength dependent characteristics of the scintillator crystal, reflector and PMT’s parts. Good agreement has been demonstrated between simulated and measured results using 21 different pin configurations

Emoke Lorincz; Gabor Erdei; Imre Peczeli; Cecilia Steinbach; Ferenc Ujhelyi; Tamas Biikki

2008-01-01

257

Research investigation on dense scintillation glass for use in total absorption nuclear cascade detectors. Final report  

Microsoft Academic Search

Three approaches to the development of a high-density scintillation ; glass were investigated. They include the increase of density of glass systems ; containlng cerium---the only systems which were known to show scintillation, the ; testing of a novel silicate glass system containlng significant concentrations of ; silver produced by ion exchange and never tested previously, and the hot pressing

Hensler

1973-01-01

258

Timing resolution improvement using DOI information in a four-layer scintillation detector for TOF-PET  

NASA Astrophysics Data System (ADS)

Depth-of-interaction (DOI) detectors are considered to be advantageous for time-of-flight positron emission tomography (TOF-PET) because they can correct timing errors arising in the scintillation crystals due to a propagation speed difference between annihilation radiation and scintillation photons. We experimentally measured this timing error, using our four-layer DOI encoding method. The upper layers exhibited the larger timing delays due to the longer path lengths after conversion from annihilation radiation into scintillation photons that traveled by zigzag paths at a speed decreased by a factor of the refractive index (n). The maximum timing delay between the uppermost and the lowermost layers was evaluated as 164 ps when n=1.47. A TOF error correction was demonstrated to improve the timing resolution of the four-layer DOI detector by 10.3%, which would increase the effective sensitivity of the scanner by about 12% comparison with a non-DOI TOF-PET scanner. This is the first step towards combining these two important fields in PET instrumentation, namely DOI and TOF, for the purpose of achieving a higher sensitivity as well as a more uniform spatial resolution.

Shibuya, Kengo; Nishikido, Fumihiko; Tsuda, Tomoaki; Kobayashi, Tetsuya; Lam, Chihfung; Yamaya, Taiga; Yoshida, Eiji; Inadama, Naoko; Murayama, Hideo

2008-08-01

259

A setup for precise measurement of resonance neutron capture by self-indication  

NASA Astrophysics Data System (ADS)

In order to measure neutron capture self-indication in the neutron energy range up to 200 keV, a setup based on a 16-section NaI(Tl) scintillation gamma detector has been created at the 500-m flight path of the IBR-30 booster (JINR-Dubna). The detector has a geometric efficiency of 80% and a total scintillator volume of 36 1. The capture self-indication ratio T?(n) for 238U has been measured on the setup in the energy region 0.465-200 keV and in the range of filter thickness from 4.78 to 306 kb-. The setup can be used for investigations including resonance self-shielding effects as well as relations between gamma-quanta multiplicity and some resonance characteristics of nuclei.

Janeva, N.; Toshkov, S.; Muradyan, G. V.; Grigorjev, Yu. V.; Georgiev, G.; Sirakov, I.; Tishin, V. G.; Zamjatnin, Yu. S.

1992-03-01

260

Directional neutron detectors for use with 14 MeV neutrons :fiber scintillation methods for directional neutron detection.  

SciTech Connect

Current Joint Test Assembly (JTA) neutron monitors rely on knock-on proton type detectors that are susceptible to X-rays and low energy gamma rays. We investigated two novel plastic scintillating fiber directional neutron detector prototypes. One prototype used a fiber selected such that the fiber width was less than 2.1mm which is the range of a proton in plastic. The difference in the distribution of recoil proton energy deposited in the fiber was used to determine the incident neutron direction. The second prototype measured both the recoil proton energy and direction. The neutron direction was determined from the kinematics of single neutron-proton scatters. This report describes the development and performance of these detectors.

Sunnarborg, Duane A.; Peel, Justin D.; Mascarenhas, Nicholas; Mengesha, Wondwosen

2005-10-01

261

Evaluation of flow cell detector configurations combining simultaneous preconcentration and scintillation detection for monitoring of pertechnetate in aqueous media.  

PubMed

Flow cell detectors were developed for simultaneous concentration and scintillation detection of technetium-99 in water. Evaluated flow cell geometries consisted of a coil and a fountain flow cell design; the latter is based on radial solution flow through a resin bed interfaced with a photomultiplier tube through a polycarbonate window. The sorptive scintillating media investigated were (1) an extractive scintillator combining a porous polystyrene resin with the extractant Aliquat-336 and fluor 2-(1-naphthyl)-5-phenyloxazole, (2) a mixed bed of organic scintillator (BC-400) and Tc-selective resin (TEVA), and (3) a mixed bed of inorganic scintillator particles (CaF2-Eu) with either TEVA resin or strong base anion-exchange resin (Dowex 1 x 8-400(Cl)). Depending on flow cell geometry and medium, the detection efficiencies for 99Tc ranged from 7.26 (BC-400/TEVA in coil geometry) to 50.20% (CaF2(Eu)/Dowex 1 x 8-400(Cl) in fountain flow cell geometry). The configuration with the highest sensitivity, CaF2(Eu)/Dowex 1 x 8-400(Cl) in coil geometry, can detect 99Tc as low as 3.78 Bq L(-1) for a 100-s count interval and a 200-mL sample, which is below the current regulatory level of 33 Bq L(-1). The issue of sensor reusability was addressed in this research, and its potential application at near neutral pH was demonstrated. The optimal sensor design was evaluated with a 99Tc-spiked synthetic groundwater matrix. PMID:16579605

Hughes, Lara D; DeVol, Timothy A

2006-04-01

262

Neutron detection and multiplicity counting using a boron-loaded plastic scintillator/bismuth germanate phoswich detector array  

SciTech Connect

Neutron detection and multiplicity counting has been investigated using a boron-loaded plastic scintillator/bismuth germanate phoswich detector array. Boron-loaded plastic combines neutron moderation (H) and detection ({sup 10}B) at the molecular level, thereby physically coupling increasing detection efficiency and decreasing die-away time with detector volume. Both of these characteristics address a fundamental limitation of thermal-neutron multiplicity counters, where {sup 3}He proportional counters are embedded in a polyethylene matrix. Separation of the phoswich response into its plastic scintillator and bismuth germanate components was accomplished on a pulse-by-pulse basis using custom integrator and timing circuits. In addition, a custom time-tag module was used to provide a time for each detector event. Analysis of the combined energy and time event stream was performed by calibrating each detector`s response and filtering based on the presence of a simultaneous energy deposition corresponding to the {sup 10}B(n,alpha) reaction products in the plastic scintillator (93 keV{sub ee}) and the accompanying neutron-capture gamma ray in the bismuth germanate (478 keV). Time-correlation analysis was subsequently performed on the filtered event stream to obtain shift-register-type singles and doubles count rates. Proof-of-principle measurements were conducted with a variety of gamma-ray and neutron sources including {sup 137}Cs, {sup 54}Mn, AmLi, and {sup 252}Cf. Results of this study indicate that a neutron-capture probability of {approximately}10% and a die-away time of {approximately}10 {micro}s are possible with a 4-detector array with a detector volume of 1600 cm{sup 3}. Simulations were performed that indicate neutron-capture probabilities on the order of 50% and die-away times of less than 4 {micro}s are realistically achievable. While further study will be required for practical application of such a detection system, the results obtained in this investigation are encouraging and may lead to a new class of high-efficiency, short die-away time neutron multiplicity counters capable of extending current nondestructive assay methods for special nuclear materials.

Miller, M.C.

1998-03-01

263

Development of a type of a one-dimensional position-sensitive scintillator fiber detector for X-ray backscatter imaging  

NASA Astrophysics Data System (ADS)

We have developed a one-dimensional position-sensitive detector (1-D PSD) for X-ray backscatter imaging which had a scintillator fiber- position-sensitive photomultiplier (PSPMT) structure. Scintillators of the detector were covered by diffused reflection material. Teflon and the fiber of the detector was covered by mirror reflection material an aluminum foil. The detector was composed of a 1×25 LYSO array which was coupled with 25 plastic fibers. Another end of these fibers was twisted into a 5×5 array and coupled with a PSPMT R8520. The detector element's area was 4.2×20 mm2 and the position resolution was 4.2 mm. We tested the positioning histogram of the detector set up an X-ray backscatter imaging system, and obtained an X-ray backscatter image from it.

Sun, Guangzhi; Chen, Ximeng; Wei, Long; Ma, Chuangxin; Zhang, Tianbao; Li, Ke; Li, Daowu; Wei, Cunfeng; Zhang, Zhiming; Hu, Tingting; Wang, Rensong; Feng, Baotong; Shuai, Lei

2008-08-01

264

Development of an application specific scintimammography detector based on a crystal scintillator array and a PSPMT  

SciTech Connect

We report the results of studies conducted with small field of view scintimammography camera based on a position-sensitive photomultiplier tube (5'' Hamamatsu R3292) and several pixelized crystal scintillator arrays made of YAP, CsI(Na) and NaI(Tl) scintillators. Laboratory tests and pre-clinical phantom studies were conducted to compare and optimize the performances of the prototypes with special emphasis on spatial resolution ({approx}2-3mm) and sufficient energy resolution for scatter rejection.

Stan Majewski; F. Farzanpay; A. Goode; Brian Kross; D. Steinbach; Andrew Weisenberger; M. Williams; Randy Wojcik

1998-05-01

265

LArGe: Background suppression using liquid argon (LAr) scintillation for 0 ??? decay search with enriched germanium (Ge) detectors  

Microsoft Academic Search

Measurements with a bare p-type high purity germanium diode (HPGe) submerged\\u000ain a 19 kg liquid argon (LAr) scintillation detector at MPIK Heidelberg are\\u000areported. The liquid argon--germanium system (LArGe) is operated as a 4$\\\\pi$\\u000aanti-Compton spectrometer to suppress backgrounds in the HPGe. This R&D is\\u000acarried out in the framework of the GERDA experiment which searches for\\u000a0$\\\

M. Di Marco; P. Peiffer; S. Schönert

2007-01-01

266

Evaluation of the Red Emitting ${\\\\rm Gd}_{2}{\\\\rm O}_{2}{\\\\rm S}\\\\!\\\\!:\\\\!\\\\!{\\\\rm Eu}$ Powder Scintillator for Use in Indirect X-Ray Digital Mammography Detectors  

Microsoft Academic Search

The aim of the present study was to investigate the imaging transfer characteristics and the luminescence efficiency (XLE) of powder scintillator for use in X-ray mammography detectors. emits in the red part of the visible spectrum, having very good spectral compatibility with optical sensors employed in digital imaging systems. Three powder scintillating screens, with coating thicknesses 33.1, 46.4 and 63.1

Christos M. Michail; George P. Fountos; Ioannis G. Valais; Nektarios I. Kalyvas; Panagiotis F. Liaparinos; Ioannis S. Kandarakis; George S. Panayiotakis

2011-01-01

267

Construction and performance of one- and two-dimensional large position-sensitive liquid and plastic scintillation detectors - an application to a neutron polarimeter  

Microsoft Academic Search

Large one- and two-dimensional position-sensitive neutron detectors have been developed. Their shapes are a long block and a square and their sizes are 100×10×7.5 cm3 and 100×100×10 cm3 for one- and two-dimensional detectors, respectively. Both liquid and plastic scintillators are employed as detector materials. Position resolutions are examined by using monoenergetic neutron beams with energies of 61.6 MeV. The obtained

H. Sakai; H. Okamura; S. Ishida; K. Hatanaka; T. Noro

1992-01-01

268

Segmented crystalline scintillators: an initial investigation of high quantum efficiency detectors for megavoltage x-ray imaging.  

PubMed

Electronic portal imaging devices (EPIDs) based on indirect detection, active matrix flat panel imagers (AMFPIs) have become the technology of choice for geometric verification of patient localization and dose delivery in external beam radiotherapy. However, current AMFPI EPIDs, which are based on powdered-phosphor screens, make use of only approximately 2% of the incident radiation, thus severely limiting their imaging performance as quantified by the detective quantum efficiency (DQE) (approximately 1%, compared to approximately 75% for kilovoltage AMFPIs). With the rapidly increasing adoption of image-guided techniques in virtually every aspect of radiotherapy, there exist strong incentives to develop high-DQE megavoltage x-ray imagers, capable of providing soft-tissue contrast at very low doses in megavoltage tomographic and, potentially, projection imaging. In this work we present a systematic theoretical and preliminary empirical evaluation of a promising, high-quantum-efficiency, megavoltage x-ray detector design based on a two-dimensional matrix of thick, optically isolated, crystalline scintillator elements. The detector is coupled with an indirect detection-based active matrix array, with the center-to-center spacing of the crystalline elements chosen to match the pitch of the underlying array pixels. Such a design enables the utilization of a significantly larger fraction of the incident radiation (up to 80% for a 6 MV beam), through increases in the thickness of the crystalline elements, without loss of spatial resolution due to the spread of optical photons. Radiation damage studies were performed on test samples of two candidate scintillator materials, CsI(Tl) and BGO, under conditions relevant to radiotherapy imaging. A detailed Monte Carlo-based study was performed in order to examine the signal, spatial spreading, and noise properties of the absorbed energy for several segmented detector configurations. Parameters studied included scintillator material, septal wall material, detector thickness, and the thickness of the septal walls. The results of the Monte Carlo simulations were used to estimate the upper limits of the modulation transfer function, noise power spectrum and the DQE for a select number of configurations. An exploratory, small-area prototype segmented detector was fabricated by infusing crystalline CsI(Tl) in a 2 mm thick tungsten matrix, and the signal response was measured under radiotherapy imaging conditions. Results from the radiation damage studies showed that both CsI(Tl) and BGO exhibited less than approximately 15% reduction in light output after 2500 cGy equivalent dose. The prototype CsI(Tl) segmented detector exhibited high uniformity, but a lower-than-expected magnitude of signal response. Finally, results from Monte Carlo studies strongly indicate that high scintillator-fill-factor configurations, incorporating high-density scintillator and septal wall materials, could achieve up to 50 times higher DQE compared to current AMFPI EPIDs. PMID:16279059

Sawant, Amit; Antonuk, Larry E; El-Mohri, Youcef; Zhao, Qihua; Li, Yixin; Su, Zhong; Wang, Yi; Yamamoto, Jin; Du, Hong; Cunningham, Ian; Klugerman, Misha; Shah, Kanai

2005-10-01

269

Simulation study comparing the imaging performance of a solid state detector with a rotating slat collimator versus parallel beam collimator setups  

NASA Astrophysics Data System (ADS)

The main goal of this work is to assess the overall imaging performance of dedicated new solid state devices compared to a traditional scintillation camera for use in SPECT imaging. A solid state detector with a rotating slat collimator will be compared with the same detector mounted with a classical collimator as opposed to a traditional Anger camera. A better energy resolution characterizes the solid state materials while the rotating slat collimator promises a better sensitivity-resolution tradeoff. The evaluation of the different imaging modalities is done using GATE, a recently developed Monte Carlo code. Several features for imaging performance evaluation were addressed: spatial resolution, energy resolution, sensitivity, and a ROC analysis was performed to evaluate the hot spot detectability. In this way a difference in perfromance was concluded for the diverse imaging techniques which allows a task dependent application of these modalities in future clinical practice.

Staelens, Steven; Vandenberghe, Stefaan; De Beenhouwer, Jan; De Clercq, Stijn; D'Asseler, Yves; Lemahieu, Ignace; Van de Walle, Rik

2004-05-01

270

LArGe: Background suppression using liquid argon (LAr) scintillation for 0??? decay search with enriched germanium (Ge) detectors  

NASA Astrophysics Data System (ADS)

Measurements with a bare p-type high purity germanium diode (HPGe) submerged in a 19 kg liquid argon (LAr) scintillation detector at MPIK-Heidelberg are reported. The liquid argon germanium system (LArGe) is operated as a 4? anti-Compton spectrometer to suppress backgrounds in the HPGe. This R&D is carried out in the framework of the Gerda experiment which searches for 0??? decays with HPGe detectors enriched in 76Ge. The goal of this work is to develop a novel method to discriminate backgrounds in 0??? search which would ultimately allow to investigate the effective neutrino mass free of background events down to the inverse mass hierarchy scale. Other applications in low-background counting are expected.

di Marco, M.; Peiffer, P.; Schönert, S.

2007-10-01

271

Single channel beta–gamma coincidence system for radioxenon measurement using well-type HPGe and plastic scintillator detectors  

NASA Astrophysics Data System (ADS)

In order to improve detection sensitivity for radioxenon isotopes, a new single channel beta–gamma coincidence system has been developed. The system combines a well-type High-purity Germanium (HPGe) detector to measure gamma or X radiation and a plastic scintillator detector to obtain electron radiation. A 133Xe sample has been produced and the radioactive concentration was determined with length-compensated method based on three internal gas proportional counters. The performance of system has been checked by measuring 133Xe sample with and without coincidence. The coincidence detection efficiency of 81 keV gamma-ray from decay of 133Xe was calibrated to be 0.34 (1±2.4%), and the Minimum detectable activity (MDA) of the beta–gamma coincidence system for 133Xe was determined to be 1.8 mBq after one day of measurement.

Xie, Feng; Jiang, Wengang; Li, Xuesong; He, Xiaobing; Zhang, Jiamei; Yu, Gongshuo

2013-11-01

272

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

SciTech Connect

Purpose: By using Monte Carlo simulations, the authors investigated the energy and angular dependence of the response of plastic scintillation detectors (PSDs) in photon beams. Methods: Three PSDs were modeled in this study: A plastic scintillator (BC-400) and a scintillating fiber (BCF-12), both attached by a plastic-core optical fiber stem, and a plastic scintillator (BC-400) attached by an air-core optical fiber stem with a silica tube coated with silver. The authors then calculated, with low statistical uncertainty, the energy and angular dependences of the PSDs' responses in a water phantom. For energy dependence, the response of the detectors is calculated as the detector dose per unit water dose. The perturbation caused by the optical fiber stem connected to the PSD to guide the optical light to a photodetector was studied in simulations using different optical fiber materials. Results: For the energy dependence of the PSDs in photon beams, the PSDs with plastic-core fiber have excellent energy independence within about 0.5% at photon energies ranging from 300 keV (monoenergetic) to 18 MV (linac beam). The PSD with an air-core optical fiber with a silica tube also has good energy independence within 1% in the same photon energy range. For the angular dependence, the relative response of all the three modeled PSDs is within 2% for all the angles in a 6 MV photon beam. This is also true in a 300 keV monoenergetic photon beam for PSDs with plastic-core fiber. For the PSD with an air-core fiber with a silica tube in the 300 keV beam, the relative response varies within 1% for most of the angles, except in the case when the fiber stem is pointing right to the radiation source in which case the PSD may over-response by more than 10%. Conclusions: At {+-}1% level, no beam energy correction is necessary for the response of all three PSDs modeled in this study in the photon energy ranges from 200 keV (monoenergetic) to 18 MV (linac beam). The PSD would be even closer to water equivalent if there is a silica tube around the sensitive volume. The angular dependence of the response of the three PSDs in a 6 MV photon beam is not of concern at 2% level.

Wang, Lilie L. W.; Klein, David; Beddar, A. Sam [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030 (United States)

2010-10-15

273

Comparison of calculation results of neutron detection efficiency for models with silicon semiconductor detector and plastic scintillator for GAMMA-400 telescope  

NASA Astrophysics Data System (ADS)

Monte Carlo calculations were performed for two models of neutron detector. The first model of the neutron detector includes the layer of polyethylene as a moderator, boron as a target for (n, ?) reaction and silicon as a detector of ?-particles. The second model consists of polyethylene layers alternating with layers of plastic-boron scintillators. Calculations were performed for parallel neutron flux with evaporation spectrum. The calculation results of neutron detection efficiency for two proposed models were analyzed and compared. The high neutron detection efficiency is attained by using a plastic-boron scintillator. Using natural boron the 10% of detection efficiency is attained and in the case of enriched boron more than 15% of detection efficiency is attained when the detector thickness is 4 cm. The model using silicon detectors provides the detection efficiency about 4%.

Dedenko, G.; Zin, Thant; Kadilin, V.; Gavrikov, I.; Tyurin, E.; Isakov, S.

2013-02-01

274

Radiation detector developments in medical applications: inorganic scintillators in positron emission tomography.  

PubMed

In recent years, a number of new gamma-ray scintillators are commercially available. These scintillators are either derived from known scintillators, e.g. Lu1-xYxAlO3: Ce (LuYAP) from LuAlO3:Ce and Lu(2(1-x))Y2xSiO5:Ce (LYSO) from Lu2SiO5:Ce or are the result of new discoveries, e.g. LaCl3:Ce and LaBr3:Ce. The first two materials are primarily of interest because of the relatively high detection efficiency and fast response; LYSO has found application in time-of-flight (TOF) positron-emission tomography (TOF PET) and the LuYAP-LYSO combination is used in small-animal PET. The halide scintillators have an excellent energy resolution of approximately 3% at 662 keV and they have a relatively high light yield. LaBr3:Ce is being studied for application in TOF PET. At the same time, the search for and research on new scintillator materials are going on. For example, LuI3:Ce is a new material with a very high light yield (approximately 90,000 photons MeV(-1)). Other examples of new materials are (C6H13NH3)2PbI4 and (C3H7NH3)2PbBr4, organic-inorganic hybrid compounds, of which the former has a very fast sub-nanosecond response. The new scintillators show great promise for new developments in medical applications, in particular, for PET systems. PMID:18321877

van Eijk, Carel W E

2008-03-05

275

Low-energy neutron detector based upon lithium lanthanide borate scintillators  

DOEpatents

An apparatus for detecting neutrons includes a cerium activated scintillation crystal containing .sup.10 B, with the scintillation crystal emitting light in response to .alpha. particles emitted from the .sup.10 B(n,.alpha.)Li* reaction. The apparatus also includes a gamma scintillator positioned adjacent the crystal and which generates light in response to gamma rays emitted from the decay of Li*. The apparatus further includes a first and a second light-to-electronic signal converter each positioned to respectively receive light from the crystal and the gamma scintillator, and each respectively outputting first and second electronic signals representative of .alpha. particles from the .sup.10 B(n,.alpha.)Li* reaction and gamma rays from the .sup.10 B(n,.alpha.)Li* reaction. The apparatus includes a coincidence circuit connected to receive the first and second signals and which generates a coincidence signal when the first and second signals coincide. The apparatus also includes a data analyzer for receiving an additional signal from at least one of the first and second converters, and for operating in response to the coincidence signal.

Czirr, John B. (Mapleton, UT)

1998-01-01

276

A scintillation triggering system for a liquid-argon neutrino detector  

SciTech Connect

The paper describes the layout of a scintillation triggering system of the large argon spectrometer at the Tagged-Neutrino Facility. It is designed to select neutrino reactions of a required type. The techniques for rapidly processing the analog signals from the trigger to exclude the detection of background events are discussed.

Belikov, S.V.; Gurzhiev, S.N.; Gutnikov, Yu.E. [Institute of High-Energy Physics, Serpukhov (Russian Federation)] [and others

1995-09-01

277

A scintillation triggering system for a liquid-argon neutrino detector  

Microsoft Academic Search

The paper describes the layout of a scintillation triggering system of the large argon spectrometer at the Tagged-Neutrino Facility. It is designed to select neutrino reactions of a required type. The techniques for rapidly processing the analog signals from the trigger to exclude the detection of background events are discussed.

S. V. Belikov; S. N. Gurzhiev; Yu. E. Gutnikov

1995-01-01

278

Scatter correction techniques in high resolution detectors based on PSPMTS and scintillator arrays: an evaluation study  

Microsoft Academic Search

SPECT images suffer from low contrast as a result of photons scatter. The standard method for excluding scatter component in pixelized scintillators is the application of an energy window around the central photopeak channel of each crystal cell, but small angle scattered photons still appear in the photopeak window and they are included in the reconstructed images. In this work

Evangelia Karali; George Loudos; Nick Sakelios; Konstantina S. Nikita; Nick Giokaris

2005-01-01

279

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

SciTech Connect

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

Cline, D.B.

1992-01-01

280

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

ERIC Educational Resources Information Center

|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…

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

2008-01-01

281

Scintillation index for two Gaussian laser beams with different wavelengths in weak atmospheric turbulence.  

PubMed

We study the propagation of the two lowest-order Gaussian laser beams with different wavelengths in weak atmospheric turbulence. Using the Rytov approximation and assuming a slow detector, we calculate the longitudinal and radial components of the scintillation index for a typical free-space laser communication setup. We find the optimal configuration of the two laser beams with respect to the longitudinal scintillation index. We show that the value of the longitudinal scintillation for the optimal two-beam configuration is smaller by more than 50% compared with the value for a single lowest-order Gaussian beam with the same total power. Furthermore, the radial scintillation for the optimal two-beam system is smaller by 35%-40% compared with the radial scintillation in the single-beam case. Further insight into the reduction of intensity fluctuations is gained by analyzing the self- and cross-intensity contributions to the scintillation index. PMID:17106466

Peleg, Avner; Moloney, Jerome V

2006-12-01

282

Synthesis and scintillation characterization of nanocrystalline Lu2O3(Eu) powder for high-resolution X-ray imaging detectors  

NASA Astrophysics Data System (ADS)

Lu2O3:Eu(CEu:5mol%) powder scintillators with nanocrystalline structures were successfully synthesized via a precipitation method and subsequent calcination treatment as a conversion material for X-ray imaging detectors. In this work, a homogeneous precipitation process was carried out using DEA(diethanolamine) as a precipitant to prepare nanocrystalline Eu-doped Gd2O3 powders. The microstructures, crystal structure and scintillation properties such as luminescent spectra, decay time and light intensity were measured as a function of calcination temperature in heat-treatment of the synthesized powder. The sample prepared at 1200°C calcination temperature showed the highest light intensity. And the scintillator showed a strong red emission light at near 611nm under photo- and X-ray luminescence for its potential X-ray imaging detector applications.

Cha, B. K.; Yong, S.-M.; Lee, S. J.; Kim, D. K.; Bae, J. H.; Cho, G.; Seo, C.-W.; Jeon, S.; Huh, Y.

2012-03-01

283

Cone beam breast CT with a high pitch (75 ?m), thick (500 ?m) scintillator CMOS flat panel detector: Visibility of simulated microcalcifications.  

PubMed

Purpose: To measure and investigate the improvement of microcalcification (MC) visibility in cone beam breast CT with a high pitch (75 ?m), thick (500 ?m) scintillator CMOS?CsI flat panel detector (Dexela 2923, Perkin Elmer).Methods: Aluminum wires and calcium carbonate grains of various sizes were embedded in a paraffin cylinder to simulate imaging of calcifications in a breast. Phantoms were imaged with a benchtop experimental cone beam CT system at various exposure levels. In addition to the Dexela detector, a high pitch (50 ?m), thin (150 ?m) scintillator CMOS?CsI flat panel detector (C7921CA-09, Hamamatsu Corporation, Hamamatsu City, Japan) and a widely used low pitch (194 ?m), thick (600 ?m) scintillator aSi?CsI flat panel detector (PaxScan 4030CB, Varian Medical Systems) were also used in scanning for comparison. The images were independently reviewed by six readers (imaging physicists). The MC visibility was quantified as the fraction of visible MCs and measured as a function of the estimated mean glandular dose (MGD) level for various MC sizes and detectors. The modulation transfer functions (MTFs) and detective quantum efficiencies (DQEs) were also measured and compared for the three detectors used.Results: The authors have demonstrated that the use of a high pitch (75 ?m) CMOS detector coupled with a thick (500 ?m) CsI scintillator helped make the smaller 150-160, 160-180, and 180-200 ?m MC groups more visible at MGDs up to 10.8, 9, and 10.8 mGy, respectively. It also made the larger 200-212 and 212-224 ?m MC groups more visible at MGDs up to 7.2 mGy. No performance improvement was observed for 224-250 ?m or larger size groups. With the higher spatial resolution of the Dexela detector based system, the apparent dimensions and shapes of MCs were more accurately rendered. The results show that with the aforementioned detector, a 73% visibility could be achieved in imaging 160-180 ?m MCs as compared to 28% visibility achieved by the low pitch (194 ?m) aSi?CsI flat panel detector. The measurements confirm that the Hamamatsu detector has the highest MTF, followed by the Dexel detector, and then the Varian detector. However, the Dexela detector, with its thick (500 ?m) CsI scintillator and low noise level, has the highest DQE at all frequencies, followed by the Varian detector, and then the Hamamatsu detector. The findings on the MC visibility correlated well with the differences in MTFs, noise power spectra, and DQEs measured for these three detectors.Conclusions: The authors have demonstrated that the use of the CMOS type Dexela detector with its high pitch (75 ?m) and thick (500 ?m) CsI scintillator could help improve the MC visibility. However, the improvement depended on the exposure level and the MC size. For imaging larger MCs or scanning at high exposure levels, there was little advantage in using the Dexela detector as compared to the aSi type Varian detector. These findings correlate well with the higher measured DQEs of the Dexela detector, especially at higher frequencies. PMID:24089917

Shen, Youtao; Zhong, Yuncheng; Lai, Chao-Jen; Wang, Tianpeng; Shaw, Chris C

2013-10-01

284

Proton transfer bis-benzazole fluors and their use in scintillator detectors  

DOEpatents

A novel class of proton transfer, bis-benzazole, fluorescent compounds, i.e., fluors, is disclosed. The novel fluors include substituted or unsubstituted 1,4-bis(2-benzazolyl)-2-hydroxybenzenes and 1,4-bis(2-benzazolyl)-2-amidobenzenes wherein the benzazolyl group may be benzoxazolyl, benzimidazolyl, benzothiazolyl, and the like. The benzazolyl groups may be substituted with one or more alkyl groups to improve solubility in organic matrix materials such as solvents, monomers, resins, polymers, and the like. The novel fluors may be used in the manufacture of fluorescent coatings, objects, scintillators, light sources and the like. The novel fluors are particularly useful for radiation-hard, solid scintillators for the detection and measurement of high energy particles and radiation.

Kauffman, Joel M. (Wayne, PA)

1994-01-01

285

Proton transfer bis-benzazole fluors and their use in scintillator detectors  

DOEpatents

A novel class of proton transfer, bis-benzazole, fluorescent compounds, i.e., fluors, is disclosed. The novel fluors include substituted or unsubstituted 1,4-bis(2-benzazolyl)-2-hydroxybenzenes and 1,4-bis(2-benzazolyl)-2-amidobenzenes wherein the benzazolyl group may be benzoxazolyl, benzimidazolyl, benzothiazolyl, and the like. The benzazolyl groups may be substituted with one or more alkyl groups to improve solubility in organic matrix materials such as solvents, monomers, resins, polymers, and the like. The novel fluors may be used in the manufacture of fluorescent coatings, objects, scintillators, light sources and the like. The novel fluors are particularly useful for radiation-hard, solid scintillators for the detection and measurement of high energy particles and radiation.

Kauffman, J.M.

1994-03-29

286

Development of a scintillation-fiber detector for real-time particle tracking  

NASA Astrophysics Data System (ADS)

The prototype of the OFFSET (Optical Fiber Folded Scintillating Extended Tracker) tracker is presented. It exploits a novel system for particle tracking, designed to achieve real-time imaging, large detection areas, and a high spatial resolution especially suitable for use in medical diagnostics. The main results regarding the system architecture have been used as a demonstration of the technique which has been patented by the Istituto Nazionale di Fisica Nucleare (INFN). The prototype of this tracker, presented in this paper, has a 20 × 20 cm2 sensitive area, consisting of two crossed ribbons of 500 micron square scintillating fibers. The track position information is extracted in real time in an innovative way, using a reduced number of read-out channels to obtain very large detection area with moderate enough costs and complexity. The performance of the tracker was investigated using beta sources, cosmic rays, and a 62 MeV proton beam.

Lo Presti, D.; Bonanno, D. L.; Longhitano, F.; Pugliatti, C.; Russo, G. V.; Aiello, S.; Cirrone, G. A. P.; Giordano, V.; Leonora, E.; Randazzo, N.; Romano, F.; Russo, M.; Sipala, V.; Stancampiano, C.; Reito, S.

2013-04-01

287

Observation of the trapping of radioactive inert gas radon on oxide glass surfaces: Macroporous scintillating-glass-fiber bundle alpha detector  

Microsoft Academic Search

We report the observation of the trapping of radioactive inert gas radon (222Rn) on oxide glass under ambient air temperature and pressure of 300 K and 760 Torr, respectively. Radon diffuses from the source, through two macroporous scintillating-glass-fiber bundle alpha detectors in series, to the end of the linear closed system filled with ambient air. The strategy is to provide

I. S. Kim; A. Appleby; G. H. Sigel Jr.

1997-01-01

288

Spectral modeling of scintillator for the NEMO3 and SuperNEMO detectors  

Microsoft Academic Search

We have constructed a GEANT4-based detailed software model of photon transport in plastic scintillator blocks and have used it to study the NEMO-3 and SuperNEMO calorimeters employed in experiments designed to search for neutrinoless double beta decay. We compare our simulations to measurements using conversion electrons from a calibration source of 207Bi and show that the agreement is improved if

J. Argyriades; R. Arnold; C. Augier; J. Baker; A. S. Barabash; M. Bongrand; G. Broudin-Bay; V. B. Brudanin; A. J. Caffrey; S. Cebrián; A. Chapon; E. Chauveau; Th. Dafni; Z. Daraktchieva; J. Díaz; D. Durand; V. G. Egorov; J. J. Evans; N. Fatemi-Ghomi; R. Flack; A. Basharina-Freshville; K.-I. Fushimi; X. Garrido; H. Gómez; B. Guillon; A. Holin; K. Holý; J. J. Horkley; Ph. Hubert; C. Hugon; F. J. Iguaz; I. G. Irastorza; N. Ishihara; C. M. Jackson; S. Jullian; S. Kanamaru; M. Kauer; O. I. Kochetov; S. I. Konovalov; V. E. Kovalenko; D. Lalanne; K. Lang; Y. Lemière; G. Lutter; G. Luzón; F. Mamedov; Ch. Marquet; J. Martin-Albo; F. Mauger; F. Monrabal; A. Nachab; I. Nasteva; I. B. Nemchenok; C. H. Nguyen; F. Nova; P. Novella; H. Ohsumi; R. B. Pahlka; F. Perrot; F. Piquemal; P. P. Povinec; B. Richards; J. S. Ricol; C. L. Riddle; A. Rodriguez; R. Saakyan; X. Sarazin; J. K. Sedgbeer; L. Serra; L. Simard; F. Šimkovic; Yu. A. Shitov; A. A. Smolnikov; S. Söldner-Rembold; I. Štekl; Y. Sugaya; C. S. Sutton; G. Szklarz; Y. Tamagawa; J. Thomas; R. Thompson; V. V. Timkin; V. I. Tretyak; Vl. I. Tretyak; V. I. Umatov; L. Vála; I. A. Vanyushin; R. Vasiliev; V. Vorobel; Ts. Vylov; D. Waters; N. Yahlali; A. Žukauskas

2011-01-01

289

The use of retro-reflective tape for improving spatial resolution of scintillation detectors  

Microsoft Academic Search

We are investigating the use of a retro-reflective tape (3M Industries), which reflects light along a line parallel to the incident light, as a substitute for Teflon tape or other reflective material used with scintillation crystals. We expect this retro-reflective property to improve the spatial resolution in large continuous crystals relative to that seen with Teflon, or other reflective coatings,

David P. McElroy; Sung-Cheng Huang; Edward J. Hoffman

2002-01-01

290

Use of retro-reflective tape for improving spatial resolution of scintillation detectors  

Microsoft Academic Search

The authors are investigating the use of a retro-reflective tape (3M Industries), which reflects light along a line parallel to the incident light, as a substitute for Teflon tape or other reflective material used with scintillation crystals. The authors expect this retro-reflective property to improve spatial resolution in large continuous crystals relative to that seen with Teflon when the reflective

D. McElroy; S. Huang; M. Dahlbom; E. Hoffman

2000-01-01

291

Discriminated neutron and X-ray radiography using multi-color scintillation detector  

Microsoft Academic Search

A new conversion screen Gd2O2S:Eu is developed, which emits red light on irradiation by thermal neutrons. By applying this in combination with the currently used Gd2O2S:Tb, a green-light scintillator, in the radiography under a neutron + X-ray coexisting field, we can easily separate the neutron image and the X-ray image by simple color-image processing. This technique enables a non-destructive and

Koichi Nittoh; Takeshi Takahara; Tadashi Yoshida; Toshiyuki Tamura

1999-01-01

292

Extension of dynamic range in X-ray radiography using multi-color scintillation detector  

Microsoft Academic Search

A new imaging system using the multi-color scintillator Gd2O2S:Eu has been developed for the X-ray radiography. In this method a color Charge Coupled Device detects the weak blue and green photons associated with the transitions from the terms like 5D1 and 5D2 in the Eu-ions as well as the dominant red photons. As these transitions become appreciable and saturate at

Koichi Nittoh; Eiji Oyaizu; Tetsuo Sakurai; Tadashi Yoshida; Koh-Ichi Mochiki

2003-01-01

293

Position sensitive scintillation detector for gamma-rays using a GSO crystal  

Microsoft Academic Search

We report the development of a gamma-ray imager using a 5 mm thick, 50 mm diameter Gd2SiO5 (GSO) crystal coupled to a 2D position-sensitive photomultiplier tube (Hamamatsu R2486). A considerable improvement in the position linearity and resolution was achieved upon placing around the GSO scintillator a glass ring which has the same thickness and the same index of refraction as

Yasuyoshi Nagai; Toshio Hyodo

1994-01-01

294

Measurement of neutron and ?-ray intensity distributions with an optical fiber-scintillator detector  

Microsoft Academic Search

On the tip of an optical fiber, a very small amount of ZnS(Ag) scintillator mixed with neutron converter and adhesive paste was painted, which can be inserted into a narrow space and moved by a fiber-driving unit controlled with a personal computer. The presented method made it possible to measure neutron flux distributions in critical assemblies, research reactors or other

C. Mori; A. Uritani; H. Miyahara; T. Iguchi; S. Shiroya; K. Kobayashi; E. Takada; R. F. Fleming; Y. K. Dewaraja; D. Stuenkel; G. F. Knoll

1999-01-01

295

Effect of scintillator crystal geometry and surface finishing on depth of interaction resolution in PET detectors: Monte Carlo simulation and experimental results using silicon photomultipliers  

NASA Astrophysics Data System (ADS)

Resolution of positron emission tomography (PET) systems benefits from information about depth of interaction (DOI) within scintillation crystals, particularly in small bore scanners or parallel plate detectors. In this investigation, the ability of the dual-ended readout detector module configuration to resolve DOI and crystal index was evaluated for a variety of detector pitches and light guide thicknesses to validate the dual-ended readout method. Experimental results with oneto- one coupling between saw-cut 2mm pitch LYSO scintillation crystals and silicon photomultipliers (SiPMs) achieved 2.1 mm DOI resolution. Monte Carlo simulations were used to investigate the effect of larger detector pitches and varied light guide thickness on the crystal index identification accuracy and DOI resolution for a pixilated crystal array in dual-ended readout configuration. It is reported that the accuracy in identifying a 2 mm scintillation crystal was >80% for detector pitches < 6 mm and that DOI resolution was < 2 mm for all detector pitches and light guide thicknesses.

Cuddy, Sarah; Reznik, Alla; Rowlands, John A.; Taghibakhsh, Farhad

2010-03-01

296

Plastic scintillator detectors for the study of transfer and breakup reactions at intermediate energies  

NASA Astrophysics Data System (ADS)

The detection of light particles associated with projectile like fragments can be used to separate transfer and breakup reactions provided the detectors cover a large solid angle. Three detection systems are described: (1) 4-pi detector in the shape of a cube, 20 cm on a side, (2) a X-Y position sensitive (delta) E-E detector having an area of 20 x 20 cm, and (3) a multielement detector consisting of eight position sensitive strips. The latter two detectors are of the phoswich type having the thin element of NE102 (tau = 2.5 ns) and the thick element of NE115 (tau = 225 ns). The performance characteristics of the three detectors are described.

Schmidt, H. R.; Bantel, M.; Chan, Y. D.; Gazes, S. M.; Kamermans, R.; Albiston, C.; Wald, S.; Stokstad, R. G.

1984-10-01

297

Experimental response function of NaI(Tl) scintillation detector for gamma photons and tomographic measurements for defect detection  

NASA Astrophysics Data System (ADS)

The response function of gamma detector is an important factor for spectrum analysis because some photons and secondary electrons may escape the detector volume before fully depositing their energy, of course destroys the ideal delta function response. An inverse matrix approach, for unfolding of observed pulse-height distribution to a true photon spectrum, is used for construction of experimental response function by formulating a 40 × 40 matrix with bin mesh (E1/2) of 0.025 (MeV)1/2 for the present measurements. A tomographic scanner system, operating in a non-destructive and non-invasive way, is also presented for inspection of density variation in any object. The incoherent scattered intensity of 662 keV gamma photons, obtained by unfolding (deconvolution) the experimental pulse-height distribution of NaI(Tl) scintillation detector, provides the desired information. The method is quite sensitive, for showing inclusion of medium Z (atomic number) material (iron) in low Z material (aluminium) and detecting a void of ˜2 mm in size for iron block, to investigate the inhomogeneities in the object. Also, the grey scale images (using “MATLAB”) are shown to visualise the presence of defects/inclusion in metal samples.

Sharma, Amandeep; Singh, Karamjit; Singh, Bhajan; Sandhu, B. S.

2011-02-01

298

Development of the dual scintillator sheet and Phoswich detector for simultaneous Alpha and Beta-rays measurement  

Microsoft Academic Search

Thin sheet type of ZnS(Ag)\\/plastic dual scintillator for simultaneous counting of alpha- and beta-particles using a organic and inorganic scintillator widely used in the radiation measurement was manufactured, which could be applicable in the contamination monitoring systems. Counting materials were manufactured by solidification of the scintillator solution which mixed scintillator, solvent, and polymer. Prepared dual scintillator is a counting material

B. K. Seo; G. H. Kim; C. H. Park; Y. H. Jung; C. H. Jung; K. W. Lee; M. J. Han

2007-01-01

299

Plastic scintillation dosimetry: Optimal selection of scintillating fibers and scintillators  

SciTech Connect

Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for four commercial models of scintillating fibers (BCF-12, BCF-60, SCSF-78, SCSF-3HF) and two models of plastic scintillators (BC-400, BC-408). The emission spectra of all six scintillators were obtained by using an optical spectrum analyzer and they were compared with theoretical behavior. For scintillation in the blue region, the signal intensity of a singly clad scintillating fiber (BCF-12) was 120% of that of the plastic scintillator (BC-400). For the multiclad fiber (SCSF-78), the signal reached 144% of that of the plastic scintillator. The intensity of the green scintillating fibers was lower than that of the plastic scintillator: 47% for the singly clad fiber (BCF-60) and 77% for the multiclad fiber (SCSF-3HF). The collected light was studied as a function of the scintillator length and radius for a cylindrical probe. We found that symmetric detectors with nearly the same spatial resolution in each direction (2 mm in diameter by 3 mm in length) could be made with a signal equivalent to those of the more commonly used asymmetric scintillators. With augmentation of the signal-to-noise ratio in consideration, this paper presents a series of comparisons that should provide insight into selection of a scintillator type and volume for development of a medical dosimeter.

Archambault, Louis; Arsenault, Jean; Gingras, Luc; Sam Beddar, A.; Roy, Rene; Beaulieu, Luc [Departement de Radio-Oncologie et Centre de Recherche en Cancerologie, Hotel-Dieu de Quebec, 11 cote du palais, Quebec, Quebec G1R 2J6 (Canada) and Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec (Canada); Department of Radiation Physics, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030 (United States); Department de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec (Canada); Departement de Radio-Oncologie et Centre de Recherche en Cancerologie, Hotel-Dieu de Quebec, 11 cote du palais, Quebec, Quebec G1R 2J6 (Canada) and Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec (Canada)

2005-07-15

300

Background rejection capabilities of a Compton imaging telescope setup with a DSSD Ge planar detector and AGATA  

NASA Astrophysics Data System (ADS)

In this work, we show the first Monte Carlo results about the performance of the Ge array which we propose for the DESPEC experiment at FAIR, when the background algorithm developed for AGATA is applied. The main objective of our study is to characterize the capabilities of the ?-spectroscopy system, made up of AGATA detectors in a semi-spherical distribution covering a 1? solid angle and a set of planar Ge detectors in a daisy configuration, to discriminate between ? sources placed at different locations.

Doncel, M.; Quintana, B.; Gadea, A.; Recchia, F.; Farnea, E.

2011-08-01

301

A Geant4 simulation code for simulating optical photons in SPECT scintillation detectors  

Microsoft Academic Search

Geant4 is an object oriented toolkit created for the simulation of High-Energy Physics detectors. Geant4 allows an accurate modeling of radiation sources and detector devices, with easy configuration and friendly interface and at the same time with great accuracy in the simulation of physical processes. While most Monte Carlo codes do not allow the simulation of the transport and boundary

S. Lo Meo; P. Bennati; M. N. Cinti; N. Lanconelli; F. L. Navarria; R. Pani; R. Pellegrini; A. Perrotta; F. Vittorini

2009-01-01

302

Plastic Scintillator Detectors for the Study of Transfer and Breakup Reactions at Intermediate Energies.  

National Technical Information Service (NTIS)

The detection of light particles associated with projectile like fragments can be used to separate transfer and breakup reactions provided the detectors cover a large solid angle. Three detection systems are described: (1) a pi detector in the shape of a ...

H. R. Schmidt M. Bantel Y. D. Chan S. M. Gazes R. Kamermans

1984-01-01

303

Radiation Detectors Scintillator-Photodiode on the Base of A2B6 Crystals for Application in Homeland Security and Medical Equipment  

Microsoft Academic Search

We have studied comparative parameters of different scintillators: CsI(Tl), CdWO4, ZnSe(Te), ZnSe(Te,O) for dual-energy radiography applications. Detectors of the scintillator-photodiode type were obtained on the basis of CsI(Tl), CdWO4 and ZnSe(Te) crystals, and their comparative study was carried out, aiming at their use in X-ray multi-energy tomography. Because of their low afterglow level (10 ppm after 10 ms), CWO and

B. V. Grinyov; V. D. Ryzhikov; S. V. Naydenov; C. F. Smith; A. D. Opolonin; E. K. Lisetskaya; N. A. Shumeiko; N. L. Kurna; G. M. Onischenko; S. E. Tretyak; S. N. Galkin; E. F. Voronkin

2006-01-01

304

Development of a scintillator detector set with counter and data acquisition for flow measurements  

NASA Astrophysics Data System (ADS)

A portable counter with data acquisition system for flow measurements was developed, using the pulse velocity technique. This consists in determining the tracer transit time mixed homogeneously to the liquid or gas pipelines. The counter comprises: (a) two CsI(Tl) crystals solid state detectors, associated with Si PIN photodiodes, with compatible sensitivity to the injected radiotracers activities; (b) amplification units; (c) analogue-to-digital interface, which processes and displays the detectors counting separately and in real time, but in a same temporal axis, via a computer screen and (d) 30-m coaxial cables for signals transmission from each detector to the processing unit. Experiments were carried out for the detector and associated electronic characterizations. The equipment showed to be suitable for flow measurements in an industrial plant, in the real situation.

da Costa, Fábio E.; Hamada, Margarida M.

2002-06-01

305

Development of an experimental system for biological studies: Scintillation and solid-track detectors as dose monitors  

NASA Astrophysics Data System (ADS)

In the context of radiobiological and radiotoxicological studies, the development of a charged-particle beam for irradiation of biological cell culture provides an opportunity to precisely control and adjust the dose and the dose rate delivered to the cells. H+ and He2+ ions are used in an energy range of 1-16 MeV at the cell entrance. A multiple scattering method of the ions on a gold foil is used to enable homogeneous irradiation of a large sample (about 1cm2). All intermediate foils traversed by the ions before impacting the cells are selected so as to limit the degradation of the beam characteristics, such as energy loss, and energy and angular straggling. The number of impacted ions is checked indirectly using a Faraday cup system at high beam flux (/>106ions/cm2/s) or directly using a NE102 scintillator and a CR39 solid nuclear track detector. In addition, a control of the particle energy is performed using a CR39 detector. Finally, the dose delivered by the ion and the dose contribution of the secondary emission are estimated. This report describes the characteristics of the irradiation system and of the experimental procedure.

Bailly, I.; Champion, C.; Massiot, P.; Savarin, P.; Poncy, J. L.; Crespin, S.; Alloy, G.; Jacob, V.; Petibon, E.

2002-01-01

306

Novel positioning method using Gaussian mixture model for a monolithic scintillator-based detector in positron emission tomography  

NASA Astrophysics Data System (ADS)

We developed a high precision position decoding method for a positron emission tomography (PET) detector that consists of a thick slab scintillator coupled with a multichannel photomultiplier tube (PMT). The DETECT2000 simulation package was used to validate light response characteristics for a 48.8 mm×48.8 mm×10 mm slab of lutetium oxyorthosilicate coupled to a 64 channel PMT. The data are then combined to produce light collection histograms. We employed a Gaussian mixture model (GMM) to parameterize the composite light response with multiple Gaussian mixtures. In the training step, light photons acquired by N PMT channels was used as an N-dimensional feature vector and were fed into a GMM training model to generate optimal parameters for M mixtures. In the positioning step, we decoded the spatial locations of incident photons by evaluating a sample feature vector with respect to the trained mixture parameters. The average spatial resolutions after positioning with four mixtures were 1.1 mm full width at half maximum (FWHM) at the corner and 1.0 mm FWHM at the center section. This indicates that the proposed algorithm achieved high performance in both spatial resolution and positioning bias, especially at the corner section of the detector.

Bae, Seungbin; Lee, Kisung; Seo, Changwoo; Kim, Jungmin; Joo, Sung-Kwan; Joung, Jinhun

2011-09-01

307

Technical Note: Removing the stem effect when performing Ir-192 HDR brachytherapy in vivo dosimetry using plastic scintillation detectors: A relevant and necessary step  

SciTech Connect

Purpose: The purpose of this study was to investigate whether or not a stem effect removal technique is necessary when performing Ir-192 HDR brachytherapy in vivo dosimetry using a scintillation detector. Methods: A red-green-blue photodiode connected to a multichannel electrometer was used to detect the light emitted from a plastic scintillation detector (PSD) during irradiation with an Ir-192 HDR brachytherapy source. Accuracy in dose measurement was compared with and without the use of stem effect removal techniques. Monochromatic and polychromatic filtration techniques were studied. An in-house template was built for accurate positioning of catheters in which the source and the PSD were inserted. Dose distribution was measured up to 5 cm from source to detector in the radial and longitudinal directions. Results: The authors found the stem effect to be particularly important when the source was close to the optical fiber guide and far from the scintillation component of the detector. It can account for up to (72{+-}3)% of the signal under clinically relevant conditions. The polychromatic filtration outperformed the monochromatic filtration as well as the absence of filtration in regard to dose measurement accuracy. Conclusions: It is necessary to implement a stem effect removal technique when building a PSD for in vivo dosimetry during Ir-192 HDR brachytherapy. The PSD that the authors have developed for this study would be suitable for such an application.

Therriault-Proulx, Francois; Beddar, Sam; Briere, Tina M.; Archambault, Louis; Beaulieu, Luc [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 94, Houston, Texas 77030 (United States) and Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada); Department of Radiation Physics, University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 94, Houston, Texas 77030 (United States); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Ho circumflex tel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec, Quebec G1R 2J6 (Canada)

2011-04-15

308

A Digital Method for the Discrimination of Neutrons and Rays With Organic Scintillation Detectors Using Frequency Gradient Analysis  

Microsoft Academic Search

A digital method for the discrimination of neutron and ?-ray events from an organic scintillator has been investigated by using frequency gradient analysis (FGA) based on the Fourier transform. Since the scintillation process and the photomultiplier tube (PMT) anode signal are often very noisy, most pulse-shape discrimination methods in a scintillation detection system (e.g., the charge comparison (CC) method or

Guofu Liu; Malcolm J. Joyce; Xiandong Ma; Michael D. Aspinall

2010-01-01

309

hybridMANTIS: a CPU-GPU Monte Carlo method for modeling indirect x-ray detectors with columnar scintillators.  

PubMed

The computational modeling of medical imaging systems often requires obtaining a large number of simulated images with low statistical uncertainty which translates into prohibitive computing times. We describe a novel hybrid approach for Monte Carlo simulations that maximizes utilization of CPUs and GPUs in modern workstations. We apply the method to the modeling of indirect x-ray detectors using a new and improved version of the code MANTIS, an open source software tool used for the Monte Carlo simulations of indirect x-ray imagers. We first describe a GPU implementation of the physics and geometry models in fastDETECT2 (the optical transport model) and a serial CPU version of the same code. We discuss its new features like on-the-fly column geometry and columnar crosstalk in relation to the MANTIS code, and point out areas where our model provides more flexibility for the modeling of realistic columnar structures in large area detectors. Second, we modify PENELOPE (the open source software package that handles the x-ray and electron transport in MANTIS) to allow direct output of location and energy deposited during x-ray and electron interactions occurring within the scintillator. This information is then handled by optical transport routines in fastDETECT2. A load balancer dynamically allocates optical transport showers to the GPU and CPU computing cores. Our hybridMANTIS approach achieves a significant speed-up factor of 627 when compared to MANTIS and of 35 when compared to the same code running only in a CPU instead of a GPU. Using hybridMANTIS, we successfully hide hours of optical transport time by running it in parallel with the x-ray and electron transport, thus shifting the computational bottleneck from optical tox-ray transport. The new code requires much less memory than MANTIS and, asa result, allows us to efficiently simulate large area detectors. PMID:22469917

Sharma, Diksha; Badal, Andreu; Badano, Aldo

2012-04-02

310

Registration of reactor neutrinos with the highly segmented plastic scintillator detector DANSSino  

NASA Astrophysics Data System (ADS)

DANSSino is a simplified pilot version of a solid-state detector of reactor antineutrino (it is being created within the DANSS project and will be installed close to an industrial nuclear power reactor). Numerous tests performed under a 3 GWth reactor of the Kalinin NPP at a distance of 11 m from the core demonstrate operability of the chosen design and reveal the main sources of the background. In spite of its small size (20 × 20 × 100 cm3), the pilot detector turned out to be quite sensitive to reactor neutrinos, detecting about 70 IBD events per day with the signal-to-background ratio about unity.

Belov, V.; Brudanin, V.; Danilov, M.; Egorov, V.; Fomina, M.; Kobyakin, A.; Rusinov, V.; Shirchenko, M.; Shitov, Yu; Starostin, A.; Zhitnikov, I.

2013-05-01

311

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

SciTech Connect

Purpose: To investigate the response of plastic scintillation detectors (PSDs) in a 6 MV photon beam of various field sizes using Monte Carlo simulations. Methods: Three PSDs were simulated: A BC-400 and a BCF-12, each attached to a plastic-core optical fiber, and a BC-400 attached to an air-core optical fiber. PSD response was calculated as the detector dose per unit water dose for field sizes ranging from 10x10 down to 0.5x0.5 cm{sup 2} for both perpendicular and parallel orientations of the detectors to an incident beam. Similar calculations were performed for a CC01 compact chamber. The off-axis dose profiles were calculated in the 0.5x0.5 cm{sup 2} photon beam and were compared to the dose profile calculated for the CC01 chamber and that calculated in water without any detector. The angular dependence of the PSDs' responses in a small photon beam was studied. Results: In the perpendicular orientation, the response of the BCF-12 PSD varied by only 0.5% as the field size decreased from 10x10 to 0.5x0.5 cm{sup 2}, while the response of BC-400 PSD attached to a plastic-core fiber varied by more than 3% at the smallest field size because of its longer sensitive region. In the parallel orientation, the response of both PSDs attached to a plastic-core fiber varied by less than 0.4% for the same range of field sizes. For the PSD attached to an air-core fiber, the response varied, at most, by 2% for both orientations. Conclusions: The responses of all the PSDs investigated in this work can have a variation of only 1%-2% irrespective of field size and orientation of the detector if the length of the sensitive region is not more than 2 mm long and the optical fiber stems are prevented from pointing directly to the incident source.

Wang, Lilie L. W.; Beddar, Sam [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)

2011-03-15

312

New application of scintillator ZnSe(Te) in scintielectronic detectors for detection of neutrons, medical imaging, explosive detection, and NDT  

NASA Astrophysics Data System (ADS)

Scintillators on the basis of AIIBVI compounds, such as ZnSe(Te), can be used for detection of secondary charged particles coming from nuclear reactions in which neutrons interact with target nuclei of atoms present in transparent materials of dispersion scintillation detectors matrices. Using unique properties of scintillator ZnSe(Te) we show possibility of increase detection efficiency for soft x-ray radiation (20 - 90 keV). The amorphous silicon flat panels and the photodiode arrays wide used for non-destructive testing and medical imaging (spatial resolution 20 - 400 mkm). By our estimations, using of such detectors in combination with thin film of ZnSe(Te) can increase efficiency of registration of x-ray radiation (for the source of 60-140kV) in 1,2 - 2 times. We obtained thin films (10-450mkm) of scintillator ZnSe(Te) on the different substrate materials and estimated the relative light yield of the layers deposited on the graphite and Al2O3 ceramic substrates and the bulk ZnSe(Te) crystal. Use of ZnSe(Te) in the low-energy "scintillator - photodiode" type detector allowed to increase accuracy of authentication of explosives (HEIMANN X-RAY INSPECTION SYSTEM EDtS10080). Using the dual energy digital radiography system prototype we obtained the x-ray images (60 projections of each object). These images are basic data for computer tomography and three-dimensional reconstruction of density and effective atomic number. The color identification palette provides clearly show variations of effective atomic number in biological and inorganic objects. So, for example, changes of calcium concentration in a bone. The research described in this publication was supported by STCU #4115 and NATO SfP-982823.

Ryzhikov, Volodymyr D.; Opolonin, Oleksandr D.; Fedorov, Alexander G.; Lysetska, Olena K.; Kostioukevitch, Sergey A.

2008-08-01

313

Beam test performance of a scintillator-based detector for the charge identification of relativistic ions  

Microsoft Academic Search

We report on the measurements performed with relativistic ions from Be to Fe, at the Fragment Separator (FRS) of the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, to test the performance of charge-sensitive detectors that were designed to separate – via multiple dE\\/dx measurements – fully stripped nuclei of cosmic origin in the experiment CALET. The latter is a space mission

P. S. Marrocchesi; O. Adriani; Y. Akaike; M. G. Bagliesi; A. Basti; G. Bigongiari; S. Bonechi; M. Bongi; M. Y. Kim; T. Lomtadze; P. Maestro; T. Niita; S. Ozawa; Y. Shimizu; S. Torii

2011-01-01

314

Absolute Dose Distribution Measurements Of Beta Sources Using A Scintillating Fiber Based Detector  

Microsoft Academic Search

Brachytherapy using catheter based high dose rate beta sources has taken nowadays an important role in out-patient cancer treatments. At the present time, there is no detector system which can record accurate quantitative doses and spatial information for Brachytherapy sources. This is partly because of the short-range of the low energy beta emission of these sources (having typically an average

Lawrence Tynes

2006-01-01

315

Measuring output factors of small fields formed by collimator jaws and multileaf collimator using plastic scintillation detectors  

SciTech Connect

Purpose: As the practice of using high-energy photon beams to create therapeutic radiation fields of subcentimeter dimensions (as in intensity-modulated radiotherapy or stereotactic radiosurgery) grows, so too does the need for accurate verification of beam output at these small fields in which standard practices of dose verification break down. This study investigates small-field output factors measured using a small plastic scintillation detector (PSD), as well as a 0.01 cm{sup 3} ionization chamber. Specifically, output factors were measured with both detectors using small fields that were defined by either the X-Y collimator jaws or the multileaf collimator (MLC). Methods: A PSD of 0.5 mm diameter and 2 mm length was irradiated with 6 and 18 MV linac beams. The PSD was positioned vertically at a source-to-axis distance of 100 cm, at 10 cm depth in a water phantom, and irradiated with fields ranging in size from 0.5x0.5 to 10x10 cm{sup 2}. The field sizes were defined either by the collimator jaws alone or by a MLC alone. The MLC fields were constructed in two ways: with the closed leaves (i.e., those leaves that were not opened to define the square field) meeting at either the field center line or at a 4 cm offset from the center line. Scintillation light was recorded using a CCD camera and an estimation of error in the median-filtered signals was made using the bootstrapping technique. Measurements were made using a CC01 ionization chamber under conditions identical to those used for the PSD. Results: Output factors measured by the PSD showed close agreement with those measured using the ionization chamber for field sizes of 2.0x2.0 cm{sup 2} and above. At smaller field sizes, the PSD obtained output factors as much as 15% higher than those found using the ionization chamber by 0.6x0.6 cm{sup 2} jaw-defined fields. Output factors measured with no offset of the closed MLC leaves were as much as 20% higher than those measured using a 4 cm leaf offset. Conclusions: The authors' results suggest that PSDs provide a useful and possibly superior alternative to existing dosimetry systems for small fields, as they are inherently less susceptible to volume-averaging and perturbation effects than larger, air-filled ionization chambers. Therefore, PSDs may provide more accurate small-field output factor determination, regardless of the collimation mechanism.

Klein, David M.; Tailor, Ramesh C.; Archambault, Louis; Wang, Lilie; Therriault-Proulx, Francois; Beddar, A. Sam [Department of Radiation Physics, Unit 94, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Departement de Radio Oncologie, Hotel Dieu de Quebec, 11 Cote du Palais Quebec, Quebec G1R 2J6 (Canada); Department of Radiation Physics, Unit 94, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Department of Radiation Physics, Unit 94, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States) and Departement de Radio Oncologie, Hotel Dieu de Quebec, 11 Cote du Palais Quebec, Quebec G1R 2J6 (Canada); Department of Radiation Physics, Unit 94, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States)

2010-10-15

316

Verification of proton range, position, and intensity in IMPT with a 3D liquid scintillator detector system  

SciTech Connect

Purpose: Intensity-modulated proton therapy (IMPT) using spot scanned proton beams relies on the delivery of a large number of beamlets to shape the dose distribution in a highly conformal manner. The authors have developed a 3D system based on liquid scintillator to measure the spatial location, intensity, and depth of penetration (energy) of the proton beamlets in near real-time. Methods: The detector system consists of a 20 x 20 x 20 cc liquid scintillator (LS) material in a light tight enclosure connected to a CCD camera. This camera has a field of view of 25.7 by 19.3 cm and a pixel size of 0.4 mm. While the LS is irradiated, the camera continuously acquires images of the light distribution produced inside the LS. Irradiations were made with proton pencil beams produced with a spot-scanning nozzle. Pencil beams with nominal ranges in water between 9.5 and 17.6 cm were scanned to irradiate an area of 10 x 10 cm square on the surface of the LS phantom. Image frames were acquired at 50 ms per frame. Results: The signal to noise ratio of a typical Bragg peak was about 170. Proton range measured from the light distribution produced in the LS was accurate to within 0.3 mm on average. The largest deviation seen between the nominal and measured range was 0.6 mm. Lateral position of the measured pencil beam was accurate to within 0.4 mm on average. The largest deviation seen between the nominal and measured lateral position was 0.8 mm; however, the accuracy of this measurement could be improved by correcting light scattering artifacts. Intensity of single proton spots were measured with precision ranging from 3 % for the smallest spot intensity (0.005 MU) to 0.5 % for the largest spot (0.04 MU). Conclusions: Our LS detector system has been shown to be capable of fast, submillimeter spatial localization of proton spots delivered in a 3D volume. This system could be used for beam range, intensity and position verification in IMPT.

Archambault, L.; Poenisch, F.; Sahoo, N.; Robertson, D.; Lee, A.; Gillin, M. T.; Mohan, R.; Beddar, S. [Departments of Radiation Physics, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030 (United States); Departments of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030 (United States); Departments of Radiation Physics, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030 (United States)

2012-03-15

317

Measuring output factors of small fields formed by collimator jaws and multileaf collimator using plastic scintillation detectors  

PubMed Central

Purpose: As the practice of using high-energy photon beams to create therapeutic radiation fields of subcentimeter dimensions (as in intensity-modulated radiotherapy or stereotactic radiosurgery) grows, so too does the need for accurate verification of beam output at these small fields in which standard practices of dose verification break down. This study investigates small-field output factors measured using a small plastic scintillation detector (PSD), as well as a 0.01 cm3 ionization chamber. Specifically, output factors were measured with both detectors using small fields that were defined by either the X-Y collimator jaws or the multileaf collimator (MLC). Methods: A PSD of 0.5 mm diameter and 2 mm length was irradiated with 6 and 18 MV linac beams. The PSD was positioned vertically at a source-to-axis distance of 100 cm, at 10 cm depth in a water phantom, and irradiated with fields ranging in size from 0.5×0.5 to 10×10 cm2. The field sizes were defined either by the collimator jaws alone or by a MLC alone. The MLC fields were constructed in two ways: with the closed leaves (i.e., those leaves that were not opened to define the square field) meeting at either the field center line or at a 4 cm offset from the center line. Scintillation light was recorded using a CCD camera and an estimation of error in the median-filtered signals was made using the bootstrapping technique. Measurements were made using a CC01 ionization chamber under conditions identical to those used for the PSD. Results: Output factors measured by the PSD showed close agreement with those measured using the ionization chamber for field sizes of 2.0×2.0 cm2 and above. At smaller field sizes, the PSD obtained output factors as much as 15% higher than those found using the ionization chamber by 0.6×0.6 cm2 jaw-defined fields. Output factors measured with no offset of the closed MLC leaves were as much as 20% higher than those measured using a 4 cm leaf offset. Conclusions: The authors’ results suggest that PSDs provide a useful and possibly superior alternative to existing dosimetry systems for small fields, as they are inherently less susceptible to volume-averaging and perturbation effects than larger, air-filled ionization chambers. Therefore, PSDs may provide more accurate small-field output factor determination, regardless of the collimation mechanism.

Klein, David M.; Tailor, Ramesh C.; Archambault, Louis; Wang, Lilie; Therriault-Proulx, Francois; Beddar, A. Sam

2010-01-01

318

Determination of a time-shift in the OPERA set-up using high-energy horizontal muons in the LVD and OPERA detectors  

NASA Astrophysics Data System (ADS)

The purpose of this work is to report the measurement of a time-shift in the OPERA set-up in a way totally independent of the Time-Of-Flight (TOF) measurements of CNGS neutrino events and without the need to know the distance between the two laboratories, CERN and LNGS, where the neutrinos are produced and detected, respectively. The LVD and OPERA experiments are both installed in the same laboratory: LNGS. The relative position of the two detectors, separated by an average distance of ˜ 160 m, allows the use of very high-energy horizontal muons to cross-calibrate the timing systems of the two detectors, using a TOF technique, which, as stated above, is totally independent of the TOF of CNGS neutrino events. Indeed, the OPERA-LVD direction lies along the so-called "Teramo anomaly", a region in the Gran Sasso massif where LVD has established, many years ago, the existence of an anomaly in the mountain structure, which exhibits a low m.w.e. thickness for horizontal directions. The "abundant" high-energy horizontal muons (nearly 100 per year) going through LVD and OPERA exist because of this anomaly in the mountain orography. The total live time of the data in coincidence between the two experiments correspond to 1200 days from mid 2007 until March 2012. The time coincidence study of LVD and OPERA detectors is based on 306 cosmic-horizontal-muon events and shows the existence of a negative time-shift in the OPERA set-up of the order of ?t AB = -(73 ± 9) when two calendar periods, A and B, are compared. The first, A, goes from August 2007 to August 2008 plus the period from January 2012 to March 2012; the second period, B, goes from August 2008 to December 2011. This result shows a systematic effect in the OPERA timing system present from August 2008 until December 2011. The size of the effect, in terms of the cosmic horizontal muons TOF, is comparable with the neutrino velocity excess recently measured by OPERA. It is probably interesting not to forget that with the MRPC technology developed by the ALICE Bologna group the TOF world record accuracy of 20 ps was reached. This technology can be implemented at LNGS for a high-precision determination of TOF with the CNGS neutrino beams. If new experiments are needed for the study of neutrino velocities they must be able to detect effects an order of magnitude smaller than the value of the OPERA systematic effect.

Agafonova, N. Yu.; Antonioli, P.; Ashikhmin, V. V.; Bari, G.; Bressan, E.; Evans, L.; Garbini, M.; Giusti, P.; Malguin, A. S.; Persiani, R.; Ryasny, V. G.; Ryazhskaya, O. G.; Sartorelli, G.; Scapparone, E.; Selvi, M.; Shakirianova, I. R.; Votano, L.; Wenniger, H.; Yakushev, V. F.; Zichichi, A.; Agafonova, N.; Alexandrov, A.; Bertolin, A.; Brugnera, R.; Büttner, B.; Chiarella, V.; Chukanov, A.; D'Ambrosio, N.; De Lellis, G.; Di Crescenzo, A.; Di Ferdinando, D.; Di Marco, N.; Dmitrievsky, S.; Dracos, M.; Dusini, S.; Ebert, J.; Ereditato, A.; Ferber, T.; Fini, R. A.; Garfagnini, A.; Giacomelli, G.; Göllnitz, C.; Gornushkin, Y.; Grianti, F.; Gustavino, C.; Hagner, C.; Hierholzer, M.; Hollnagel, A.; Jakovcic, K.; Jollet, C.; Klicek, B.; Kose, U.; Lenkeit, J.; Ljubicic, A.; Longhin, A.; Malgin, A.; Mandrioli, G.; Matveev, V.; Mauri, N.; Medinaceli, E.; Meregaglia, A.; Muciaccia, M. T.; Naumov, D.; Olshevsky, A.; Paoloni, A.; Pastore, A.; Patrizii, L.; Pozzato, M.; Pupilli, F.; Rosa, G.; Rostovtseva, I.; Russo, A.; Ryazhskaya, O.; Schembri, A.; Shakirianova, I.; Sheshukov, A.; Simone, S.; Sioli, M.; Sirignano, C.; Sirri, G.; Spinetti, M.; Stanco, L.; Stipcevic, M.; Tenti, M.; Terranova, F.; Tioukov, V.; Votano, L.; Wonsak, B.; Yakushev, V.; Zaitsev, Y.; Zemskova, S.

2012-06-01

319

Designing Electronics and PMT Housing for a Liquid Scintillation Detector to be Used for Measuring Muon-Induced Processes at Homestake  

NASA Astrophysics Data System (ADS)

Understanding the backgrounds produced by muon-induced processes is important to the success of experiments searching for rare event physics such as neutrinoless double-beta decay, dark matter, or neutrino oscillations, which require extremely low backgrounds. Measuring these muon-induced processes is vital for the low background experiments planned for the Sanford Lab. We have designed a detector to measure the muon-induced backgrounds produced underground. Our detector consists of a 10.8 liter scintillator joined with two PMT's. We will present our design for housing the PMT's, including their attachment to the scintillator and necessary magnetic shielding. We will also present our design for a voltage divider that was constructed and tested for use on the PMT's. )

Woltman, Brian; Davis, Patrick; Mei, Dongming; Zhang, Chao

2010-02-01

320

Designing Electronics and PMT Housing for a Liquid Scintillator Detector to be Used for Measuring Muon-Induced Processes at Homestake  

NASA Astrophysics Data System (ADS)

Understanding the backgrounds produced by muon-induced processes is important to the success of experiments searching for rare event physics such as neutrinoless double-beta decay, dark matter, or neutrino oscillations, which require extremely low backgrounds. Measuring these muon-induced processes is vital for the low background experiments planned for the Sanford Lab. We have designed a detector to measure the muon-induced backgrounds produced underground. Our detector consists of a 10.8 liter scintillator joined with two PMT's. We will present our design for housing the PMT's, including their attachment to the scintillator and necessary magnetic shielding. We will also present our design for a voltage divider that was constructed and tested for use on each of the PMT's.

Woltman, Brian; Davis, Patrick; Mei, Dongming; Zhang, Chao

2009-10-01

321

MCNP modelling of scintillation-detector gamma-ray spectra from natural radionuclides.  

PubMed

gamma-ray spectra of natural radionuclides are simulated for a BGO detector in a borehole geometry using the Monte Carlo code MCNP. All gamma-ray emissions of the decay of 40K and the series of 232Th and 238U are used to describe the source. A procedure is proposed which excludes the time-consuming electron tracking in less relevant areas of the geometry. The simulated gamma-ray spectra are benchmarked against laboratory data. PMID:12201154

Hendriks, P H G M; Maucec, M; de Meijer, R J

2002-09-01

322

AMoRE experiment: a search for neutrinoless double beta decay of 100Mo isotope with 40Ca100MoO4 cryogenic scintillation detector  

Microsoft Academic Search

AMoRE (Advanced Mo based Rare process Experiment) collaboration is going to use calcium molybdate crystals as cryogenic scintillation detector in a search for neutrinoless DBD of 100Mo isotope. Simultaneous detection of phonons and light will be used to reject internal background. A FWHM resolution of 0.2% in the phonon channel has been achieved with a 0.5 cm3 crystal. Several 40Ca100MoO4

H Bhang; R S Boiko; D M Chernyak; J H Choi; S Choi; F A Danevich; K V Efendiev; C Enss; A Fleischmann; A M Gangapshev; L Gastaldo; A M Gezhaev; Y S Hwang; H Jiang; W G Kang; V V Kazalov; N D Khanbekov; H J Kim; K B Kim; S K Kim; S C Kim; Y D Kim; Y H Kim; V V Kobychev; V N Kornoukhov; V V Kuzminov; V M Mokina; H S Lee; J I Lee; J M Lee; K B Lee; M J Lee; M K Lee; S J Lee; J Li; X Li; S S Myung; A S Nikolaiko; S Olsen; S I Panasenko; D V Poda; R B Podviyanuk; O G Polischuk; P A Polozov; S S Ratkevich; Y Satou; J H So; K Tanida; V I Tretyak; S P Yakimenko; Q Yue; Y Yuryev

2012-01-01

323

Portal, freight and vehicle monitor performance using scintillating glass fiber detectors for the detection of plutonium in the Illicit Trafficking Radiation Assessment Program  

Microsoft Academic Search

Neutron-sensitive scintillating glass fiber sensors provide several advantages over neutron-sensitive gas-tubes for plutonium detection and surveillance. Large area detectors and higher effective neutron capture density provide significant improvements in sensitivity versus cost. The glass sensors offer a wide dynamic counting range, fast response time, no transport hazard, greater operator safety and lower micro-phonic susceptibility relative to conventional 3He and 10BF3

R. Seymour; C. D. Hull; T. Crawford; B. Coyne; M. Bliss; R. A. Craig

2001-01-01

324

Effect of crystal shape, size and reflector type on operation characteristics of gamma-radiation detectors based on CsI(Tl) and CsI(Na) scintillators  

Microsoft Academic Search

Operation characteristics of CsI(Tl) and CsI(Na) scintillation detectors, to a large degree connected with light collection in crystals, are calculated for various shapes, sizes and reflecting surface types. Allowance is made for the true light reflection indicatrix which is characterized by the effective mirror constituent of the reflected light, p. Its value ?p?, averaged over incidence angle, is used for

M. E. Globus; B. V. Grinyov; M. A. Ratner

1996-01-01

325

Radiation background in a LaBr3(Ce) gamma-ray scintillation detector.  

PubMed

Gamma-ray spectral analyses with a 5-cm × 5-cm LaBr3(Ce) detector and a NaI(Tl) detector of the same size show that the LaBr3(Ce) has much better gamma-ray peak resolution and full-energy peak counting efficiency but worse detection sensitivity. The LaBr3(Ce) detector has relatively high intrinsic radiation background due to the naturally occurring La radioisotope in lanthanum. Although this La background is entirely below the energy of 1,500 keV, additional background is in the energy region between 1,500 keV and 2,750 keV. The manufacturer attributes this radiation to alpha particles emitted by the five short-lived progeny of an Ac impurity. Comparative values for peak resolution, full-energy peak counting efficiency, and detection sensitivity are reported for Am, Co, and Cs. Results of counting Cs sources at two activity levels demonstrate the impact of background on detection sensitivity. PMID:22048488

Rosson, Robert; Lahr, Jeffrey; Kahn, Bernd

2011-12-01

326

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

PubMed Central

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

Mondal, Nagendra Nath

2009-01-01

327

Extraction of depth-dependent perturbation factors for parallel-plate chambers in electron beams using a plastic scintillation detector  

SciTech Connect

Purpose: This work presents the experimental extraction of the overall perturbation factor P{sub Q} in megavoltage electron beams for NACP-02 and Roos parallel-plate ionization chambers using a plastic scintillation detector (PSD). Methods: The authors used a single scanning PSD mounted on a high-precision scanning tank to measure depth-dose curves in 6, 12, and 18 MeV clinical electron beams. The authors also measured depth-dose curves using the NACP-02 and PTW Roos chambers. Results: The authors found that the perturbation factors for the NACP-02 and Roos chambers increased substantially with depth, especially for low-energy electron beams. The experimental results were in good agreement with the results of Monte Carlo simulations reported by other investigators. The authors also found that using an effective point of measurement (EPOM) placed inside the air cavity reduced the variation of perturbation factors with depth and that the optimal EPOM appears to be energy dependent. Conclusions: A PSD can be used to experimentally extract perturbation factors for ionization chambers. The dosimetry protocol recommendations indicating that the point of measurement be placed on the inside face of the front window appear to be incorrect for parallel-plate chambers and result in errors in the R{sub 50} of approximately 0.4 mm at 6 MeV, 1.0 mm at 12 MeV, and 1.2 mm at 18 MeV.

Lacroix, Frederic; Guillot, Mathieu; McEwen, Malcolm; Cojocaru, Claudiu; Gingras, Luc; Beddar, A. Sam; Beaulieu, Luc [Departement de Radio-Oncologie, Centre hospitalier de l'Universite de Montreal (CHUM), 1560 Sherbrooke Est, Montreal, Quebec H2L 4M1 (Canada) and Departement de Physique, Universite de Montreal, Pavillon Roger-Gaudry (D-428), 2900 Boul. Edouard-Montpetit, Montreal, Quebec H3T 1J4 (Canada); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Ho circumflex tel-Dieu de Quebec, Centre hospitalier Universitaire de Quebec (CHUQ), Quebec, Quebec G1R 2J6 (Canada); Ionizing Radiation Standards, Institute for National Measurement Standards, National Research Council (NRC), Ottawa, Ontario K1A 0R6 (Canada); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Ho circumflex tel-Dieu de Quebec, Centre hospitalier Universitaire de Quebec (CHUQ), Quebec, Quebec G1R 2J6 (Canada); Department of Radiation Physics, Unit 94, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre hospitalier Universitaire de Quebec (CHUQ), Quebec, Quebec G1R 2J6 (Canada)

2010-08-15

328

Fiber Optics at the JLab CLAS12 Detector  

NASA Astrophysics Data System (ADS)

The performance of wavelength shifting fibers, WLS, and method of coupling these fibers to extruded polystyrene scintillators are currently under study at James Madison University. These components are two of the main elements for the PCAL, preshower calorimeter, proposed as part of the 12 GeV upgrade for the CLAS detector at Jefferson Laboratory. The WLS fibers have been prepared, optically coupled to scintillator, and tested in order to determine their overall performance as a method of readout. Methods of coupling fiber to scintillator, a description of the test setup, test methods, PCAL readout performance, and fabrication recommendations will be presented.

Kroon, John; Giovanetti, Kevin

2008-10-01

329

A high-resolution detector based on liquid-core scintillating fibres with readout via an electron-bombarded charge-coupled device  

NASA Astrophysics Data System (ADS)

This paper is a presentation of results from tests in a 5 GeV/c hadron beam of detectors based on liquid-core scintillating fibres, each fibre consisting of a glass capillary filled with organic liquid scintillator. Fibre readout was performed via an Electron-Bombarded Charge-Coupled Device (EBCCD) image tube, a novel instrument that combines the functions of a high-gain, gated image intensifier and a Charge-Coupled Device. Using 1-methylnaphthalene doped with 3 g/l of R45 as liquid scintillator, the attenuation lengths obtained for light propagation over distances greater than 16 cm were 1.5 m in fibres of 20 ?m core and 1.0 m in fibres of 16 ?m core. For particles that crossed the fibres of 20 ?m core at distances of ~ 1.8 cm and ~ 95 cm from the fibres' readout ends, the recorded hit densities were 5.3 mm-1 and 2.5 mm-1 respectively. Using 1-methylnaphthalene doped with 3.6 g/l of R39 as liquid scintillator and fibres of 75 ?m core, the hit density obtained for particles that crossed the fibres at a distance of ~ 1.8 cm from their readout ends was 8.5 mm-1. With a specially designed bundle of tapered fibres, having core diameters that smoothly increase from 16 ?m to 75 ?m, a spatial precision of 6 ?m was measured.

Cianfarani, C.; Duane, A.; Fabre, J.-P.; Frenkel, A.; Golovkin, S. V.; Gorin, A. M.; Harrison, K.; Kozarenko, E. N.; Kushnirenko, A. E.; Ladygin, E. A.; Martellotti, G.; Medvedkov, A. M.; Nass, P. A.; Obudovski, V. P.; Penso, G.; Petukhov, Yu. P.; Siegmund, W. P.; Tyukov, V. E.; Vasilchenko, V. G.

1994-02-01

330

Evaluation of a novel noncontact spectrally and spatially resolved reflectance setup with continuously variable source-detector separation using silicone phantoms  

NASA Astrophysics Data System (ADS)

We present a new variant of a noncontact, oblique incidence spatially resolved reflectance setup. The continuously variable source detector separation enables adaptation to high and low albedo samples. Absorption (?a) and reduced scattering coefficients (?'s) are determined in the wavelength range of 400-1000 nm using a lookup table, calculated by a Monte Carlo simulation of the light transport. The method is characterized by an silicone phantom study covering a wide parameter range 0.01 mm-1 <= ?a <= 2.5 mm-1 and 0.2 mm-1 <= ?'s <= 10 mm-1, which includes the optical parameters of tissue in the visible and near infrared. The influence of the incident angle and the detection aperture on the simulated remission was examined. Using perpendicular incidence and 90-deg detection aperture in the Monte Carlo simulation in contrast to the experimental situation with 30-deg incidence and 4.6-deg detection aperture is shown to be valid for the parameter range ?'s > 1 mm-1 and ?a < 1.2 mm-1. A Mie calculation is presented, showing that a decreasing reduced scattering coefficient for increasing absorption can be the consequence of real physics instead of cross talk.

Andree, Stefan; Reble, Carina; Helfmann, Jürgen; Gersonde, Ingo; Illing, Gerd

2010-11-01

331

Avalanche Photodiode for liquid xenon scintillation: quantum efficiency and gain  

NASA Astrophysics Data System (ADS)

We report on measurements with a large area, silicon Avalanche Photodiode (APD) as photodetector for the ultraviolet scintillation light of liquid xenon (LXe) at temperatures between 167 and 188 K. The maximum gain of the APD for the scintillation light from a 210Po ?-source in LXe was 5.3 × 103. Based on the geometry of the setup, the quantum efficiency of the APD was measured at 34% ± 5% at the mean scintillation wavelength of 178 nm. The high quantum efficiency and high gain of the APD make it an attractive alternative UV photon sensor to PMTs for LXe detectors, especially for experiments requiring high light yields, such as dark matter searches for Weakly Interacting Massive Particles, or a Compton telescope in MeV ?-ray astronomy.

Shagin, P.; Gomez, R.; Oberlack, U.; Cushman, P.; Sherwood, B.; McClish, M.; Farrell, R.

2009-01-01

332

Determination of optimal boundary for algorithmic method of plastic scintillator-based radiation detector against nuclear terrorism  

Microsoft Academic Search

A plastic scintillator-based radiation portal monitoring system has played an important role in preventing and detecting illicit trafficking of nuclear and radioactive materials. The limited spectroscopic information of the plastic scintillator material makes it difficult to discriminate radioactive materials of concern from naturally occurring radioactive materials (NORM) or background radiation. This has an impact on operations and surveillance costs. Various

Sung-Woo Kwak; Sung Soon Jang; Ho-Sik Yoo

2010-01-01

333

Gamma-ray multiplicity and neutron resonance parameter measurements with the Dubna 4pi detector Romashka  

Microsoft Academic Search

A set-up based on a 16-section NaI(Tl) scintillation detector has been created at the 500 m flight-path of the IBR-30 booster in Dubna. The total volume of the detector is 36 liters, and the geometric efficiency is 80 percent. This detector measures gamma-cascades from resolved neutron resonances to obtain gamma-multiplicity spectra from neutron capture events. The 10B loaded converter, positioned

G. P. Georgiev; N. G. Panajotova

1997-01-01

334

Investigation of crystal surface finish and geometry on single LYSO scintillator detector performance for depth-of-interaction measurement with silicon photomultipliers  

NASA Astrophysics Data System (ADS)

Depth of Interaction (DOI) information can improve quality of reconstructed images acquired from Positron Emission Tomography (PET), especially in high resolution and compact scanners dedicated for breast, brain, or small animal imaging applications. Additionally, clinical scanners with time of flight capability can also benefit from DOI information. One of the most promising methods of determining DOI in a crystal involves reading the signal from two ends of a scintillation crystal, and calculating the signal ratio between the two detectors. This method is known to deliver a better DOI resolution with rough crystals compared to highly polished crystals. However, what is still not well studied is how much of a tradeoff is involved between spatial, energy, temporal, and DOI resolutions as a function of the crystal surface treatment and geometry with the use of Silicon Photomultipliers (SiPM) as the photo detectors. This study investigates the effects of different crystal surface finishes and geometries on energy, timing and DOI resolutions at different crystal depths. The results show that for LYSO scintillators of 1.5×1.5×20 mm3 and 2×2×20 mm3 with their surfaces finished from 0.5 to 30 ?m roughness, almost the same energy and coincidence timing resolutions were maintained, around 15% and 2.4 ns, respectively across different crystal depths, while the DOI resolutions were steadily improved from worse than 5 mm to better than 2 mm. They demonstrate that crystal roughness, with proper surface preparing, does not have a significant effect on the energy and coincidence timing resolutions in the crystals examined, and there does not appear to be a tradeoff between improving DOI resolution and degrading other detector performances. These results will be valuable to guide the selection of crystal surface conditions for developing a DOI measurable PET detector with a full array of LYSO scintillators coupled to SiPM arrays.

Bircher, Chad; Shao, Yiping

2012-11-01

335

LaCl3(Ce) scintillation detector applications for environmental gamma-ray measurements of low to high dose rates  

NASA Astrophysics Data System (ADS)

A new cerium-doped LaCl3(Ce) scintillator is evaluated with respect to the application in environmental gamma-ray dosimetry and spectrometry. The scintillator is very attractive for gamma-ray spectrometry in the case of high count rate, because it has excellent energy resolution and fast decay time. The performance characteristics of a scintillator with a 25.4 mm×25.4 mm LaCl3(Ce) crystal are studied and compared to those of a NaI(Tl) scintillator with the same size crystal. Acquired pulse height spectra are converted to dose rates by using the G(E) function method. Though the LaCl3(Ce) crystal itself produces a rather high background in the crystal itself, the scintillator provides good energy information and dose-rate readings from low to high-level (several mGy/h) by subtracting the self-background. The properties of LaCl3(Ce) scintillator suggest that the scintillator could be a promising candidate for monitoring at high dose levels as in emergencies, as well as at ordinary levels of background radiation.

Tsutsumi, Masahiro; Tanimura, Yoshihiko

2006-02-01

336

The Application of the BrilLanCe Series Scintillation Detector in the Spectrometer of Neutral Particles for the Satellite Experiment Zina-Nt  

NASA Astrophysics Data System (ADS)

Spectrometric detector complex ZINA-NT is intended to study a radiation conditions onboard satellite and characteristics of hard X-ray and gamma-ray fluxes from GRB, solar flares and to detect other non-stationary fluxes of cosmic gamma-rays. The advantages for using of this new detector for modification of present neutral particles detector on the base of CsI(Tl) are discussed. Scintillation detectors based on BrilLanCe series crystal have got very small lighting time, an excellent energy resolution and light output, more intensive than devices based on CsI(Tl). Using of BrilLanCe series crystal instead of CsI(Tl) ones allows to detect terrestrial gamma flashes (TGF), gamma ray bursts (GRB) and solar flares with smaller time durations and intensities. Moreover, the counts rate linearity region of BrilLanCe detectors is extended up to 106 s-1 and it allows to observe a very intensive events. So, the using of such type of detector permits us the possibility to separate gamma-quanta and neutrons on the timescales less than 50 microseconds.

Arkhangelskaja, Irene V.; Arkhangelsky, Andrey I.; Batischev, Alexey. G.; Galper, Arkady M.; Kondratyeva, Natalya V.; Naumov, Petr Yu.

337

Spatial Resolution Calculation of Hodoscopic Scintillation Detectors Based on Hodoscopic FEhU's Large Angles of Incident Particle Trajectories.  

National Technical Information Service (NTIS)

Calculation results of scintillation hodoscope spatial resolution based on HPM-30 hodoscope photomultipliers for timing to the centre of gravity and pulse centroid are presented. According to the calculations the best space resolution is quaranted by the ...

V. V. Borog V. V. Dronov V. G. Vasil'chenko V. I. Rykalin

1986-01-01

338

Green River Community College Cosmic Ray Detector  

NASA Astrophysics Data System (ADS)

The Washington Area Large scale Time coincidence Array (WALTA) researches high-energy cosmic ray and has placed particle detector arrays around the Seattle area to increase the accuracy of muon information. Green River Community College is one of the schools in collaboration with WALTA and offers its students under-graduate research by working with the particle detector arrays, data collecting and reporting. The student's work ranges from polishing scintillators and planning the physical setup of detector components to solving data acquisition problems.

Roma, Andrea; Harrington, Crissy; Isic, Mirela; Adams, Andrew; Draper, Ron

2008-05-01

339

Composite CaWO4 Detectors for the CRESST-II Experiment  

Microsoft Academic Search

CRESST-II, standing for Cryogenic Rare Events Search with Superconducting Thermometers phase II, is an experiment searching for Dark Matter. In the LNGS facility in Gran Sasso, Italy, a cryogenic detector setup is operated in order to detect WIMPs by elastic scattering off nuclei, generating phononic lattice excitations and scintillation light. The thermometers used in the experiment consist of a tungsten

M. Kiefer; G. Angloher; M. Bauer; I. Bavykina; A. Bento; A. Brown; C. Bucci; C. Ciemniak; C. Coppi; G. Deuter; F. Von Feilitzsch; D. Hauff; S. Henry; P. Huff; J. Imber; S. Ingleby; C. Isaila; J. Jochum; M. Kimmerle; H. Kraus; J.-C. Lanfranchi; R. F. Lang; M. Malek; R. McGowan; V. B. Mikhailik; E. Pantic; F. Petricca; S. Pfister; W. Potzel; F. Pröbst; S. Roth; K. Rottler; C. Sailer; K. Schäffner; J. Schmaler; S. Scholl; W. Seidel; L. Stodolsky; A. J. B. Tolhurst; I. Usherov; W. Westphal

2009-01-01

340

Phoswich detectors combining doubly or triply ZnS(Ag), NE102A, BGO and\\/or NaI(Tl) scintillators for simultaneous counting of alpha, beta and gamma rays  

Microsoft Academic Search

Phoswich detectors for simultaneous counting of alpha, beta and gamma rays have been developed: ZnS(Ag)\\/Au Mylar\\/NE102A, ZnS(Ag)\\/Au Mylar\\/BGO and ZnS(Ag)\\/NaI(Tl) for alpha and beta(gamma) rays and ZnS(Ag)\\/Au Mylar\\/NE102A\\/BGO and ZnS(Ag)\\/NE102A\\/NaI(Tl) for alpha, beta and gamma rays. They were prepared by coupling a ZnS(Ag) film scintillator for alpha counting with a scintillator(s) for beta and gamma counting having different rise time.

Shigekazu Usuda; Hitoshi Abe; Akira Mihara

1994-01-01

341

Gamma-ray and electron response in doped alkali halide scintillators  

Microsoft Academic Search

The wide angle Compton coincidence technique was used to study non-proportionality of light yield and intrinsic resolution of doped alkali halides. The tested scintillators were 1 inch × 1 inch cylindrical crystals of NaI:Tl, CsI:Na and CsI:Tl. The experimental setup comprised a High Purity Germanium detector and the tested samples coupled to a photomultiplier. The results obtained for Compton electrons

L. Swiderski; M. Moszynski; W. Czarnacki; M. Szawlowski; T. Szczesniak; G. Pausch; C. Plettner; K. Roemer; P. Schotanus

2011-01-01

342

A PHOSWICH WELL DETECTOR FOR RADIOXENON MONITORING  

SciTech Connect

Devices to measure the amount of radioactive xenon in the atmosphere have been installed in several locations around the world as part of the International Monitoring System to detect nuclear weapons testing. These devices extract small samples of xenon from large volumes of air and look for characteristic radioxenon isotopes emitting beta and gamma radiation in coincidence. To detect these coincidences, they currently employ a complex system of separate beta and gamma detectors which is very sensitive, but which requires careful calibration and gain matching of several detectors and photomultiplier tubes to achieve desired detection limits. An alternative to separate beta and gamma detectors is the use of a single phoswich detector in which beta-gamma coincidences are detected by pulse shape analysis. The phoswich detector consists of a plastic scintillator (absorbing betas) optically coupled to a CsI(Tl) scintillator (absorbing gammas) and thus requires only a single photomultiplier tube and electronics readout channel, greatly simplifying setup and calibration. In this paper, we present the results from an experimental evaluation of two phoswich well detector prototypes, including energy resolution, 2 D beta/gamma energy histograms from a variety of test sources, and background count rates. From these measurements, we derive detector properties such as coincidence detection efficiency, background rejection and the ability to separate beta only, gamma only, and coincidence events. We will further discuss setup and calibration procedures and compare them to those for existing detector systems.

Hennig, Wolfgang; Tan, Hui; Fallu-Labruyere, A.; Warburton, William K.; McIntyre, Justin I.; Gleyzer, A.

2007-08-21

343

950 keV X-Band Linac For Material Recognition Using Two-Fold Scintillator Detector As A Concept Of Dual-Energy X-Ray System  

SciTech Connect

One of the advantages of applying X-band linear accelerator (Linac) is the compact size of the whole system. That shows us the possibility of on-site system such as the custom inspection system in an airport. As X-ray source, we have developed X-band Linac and achieved maximum X-ray energy 950 keV using the low power magnetron (250 kW) in 2 {mu}s pulse length. The whole size of the Linac system is 1x1x1 m{sup 3}. That is realized by introducing X-band system. In addition, we have designed two-fold scintillator detector in dual energy X-ray concept. Monte carlo N-particle transport (MCNP) code was used to make up sensor part of the design with two scintillators, CsI and CdWO4. The custom inspection system is composed of two equipments: 950 keV X-band Linac and two-fold scintillator and they are operated simulating real situation such as baggage check in an airport. We will show you the results of experiment which was performed with metal samples: iron and lead as targets in several conditions.

Lee, Kiwoo; Natsui, Takuya; Hirai, Shunsuke; Uesaka, Mitsuru [University of Tokyo, 2-22 Tokai-mura, Ibaraki-ken 319-1188 (Japan); Hashimoto, Eiko [Japan atomic energy agency (JAEA), 4-49 Muramatsu Tokai-mura, Ibaraki-ken (Japan)

2011-06-01

344

Direct Deposition of Microcolumnar Scintillator on CMOS SSPM Array: Toward a Photon Counting Detector for X-Ray/Gamma Ray Imaging  

SciTech Connect

We are developing a modular, low-cost, photon-counting detector based on a scintillator coupled to a solid-state photodetector. A working prototype was successfully developed by depositing CsI:Tl directly onto a CMOS SSPM array designed by RMD and custom-fabricated by a commercial foundry. The device comprised a 6x6 array of 1.5x1.5 mm{sup 2} macro-pixels, each containing a 36x36 array of resistively coupled micro-pixels, that was subjected to vapor deposition of columnar CsI:Tl. Direct deposition eliminates the gap between the scintillator and SSPM and creates a better optical bond than does index-matching grease. This paper compares the performance of SSPMs with directly deposited CsI:Tl, in terms of signal-to-noise ratio and light spread, against devices using monolithic single crystals or pixelated single crystals coupled to the SSPM. Due to the reduction in light scattering and optical losses in the interface, the directly deposited CsI:Tl demonstrated significantly better position sensitivity, with at least a factor of 2 increase in SNR compared to a single crystal. These data indicate that a photodetector with substantially smaller macro-pixel dimensions than used here could be used to implement a low-energy X-ray/gamma-ray imaging and spectroscopy detector, particularly for applications where high resolution is of prime importance.

Prekas, G.; Breen, M.; Sabet, H.; Bhandari, H.; Derderian, G.; Robertson, F. Jr; Stapels, C. J.; Christian, J.; Cool, S.; Nagarkar, V. V. [Radiation Monitoring Devices, Inc., 44 Hunt Street, Watertown, Massachusetts 02472 (United States)

2011-12-13

345

Scintillator Waveguide For Sensing Radiation  

DOEpatents

The present invention is an apparatus for detecting ionizing radiation, having: a waveguide having a first end and a second end, the waveguide formed of a scintillator material wherein the therapeutic ionizing radiation isotropically generates scintillation light signals within the waveguide. This apparatus provides a measure of radiation dose. The apparatus may be modified to permit making a measure of location of radiation dose. Specifically, the scintillation material is segmented into a plurality of segments; and a connecting cable for each of the plurality of segments is used for conducting scintillation signals to a scintillation detector.

Bliss, Mary (West Richland, WA); Craig, Richard A. (West Richland, WA); Reeder; Paul L. (Richland, WA)

2003-04-22

346

A comparative evaluation of scatter correction techniques in high resolution detectors based on PSPMTs and scintillator arrays  

Microsoft Academic Search

SPECT images suffer from low contrast as a result of photons scatter. The standard method for excluding scatter component in pixelized scintillators is the application of an energy window around the central photopeak channel of each crystal cell, but small angle scattered photons still appear in the photopeak window and they are included in the reconstructed images. A number of

E. Karalil; G. Loudos; N. Sakelios; K. S. Nikita; N. Giokaris

2004-01-01

347

A Comparative Evaluation of Scatter Correction Techniques in High-Resolution Detectors Based on PSPMTs and Scintillator Arrays  

Microsoft Academic Search

Single photon emission computed tomography images suffer from low contrast as a result of photon scatter. The standard method for excluding the scatter component in pixelized scintillators is the application of an energy window around the central photopeak channel of each crystal cell, but small angle scattered photons still appear in the photopeak window, and they are included in the

Evangelia Karali; George K. Loudos; Nicolas Sakellios; Konstantina S. Nikita

2006-01-01

348

Scintillation index for N Gaussian laser beams with different wavelengths in weak atmospheric turbulence  

NASA Astrophysics Data System (ADS)

We study the scintillation index of N partially overlapping lowest order Gaussian laser beams with different wavelengths in weak atmospheric turbulence. Assuming a Von Karman turbulence spectrum and slow detector response and using the Rytov approximation we calculate the longitudinal and radial components of the scintillation index for typical free-space laser communication setups. We find the initial beam separation that minimizes the longitudinal scintillation and corresponds to the optimal beam configuration. Further reduction of the longitudinal scintillation is obtained by optimizing with respect to both initial beam separation and initial spot size. The longitudinal scintillation of the optimal N-beam configurations is inversely proportional to N, resulting in a 92% reduction for a 9-beam system compared with the single beam value. The existence of the minimum of longitudinal scintillation is not very sensitive to the form of the turbulence spectrum. Moreover, the radial scintillation values for the optimal N-beam configurations are found to be significantly smaller than the corresponding single beam values, and this reduction effect also grows with increasing N.

Peleg, A.; Moloney, J. V.

2007-03-01

349

Decay time and pulse shape discrimination of liquid scintillators based on novel solvents  

NASA Astrophysics Data System (ADS)

Over the past few years the liquid scintillation technique employed for particle detection applications has undergone a significant technological breakthrough with the introduction of novel solvents tailored to address the concerns about toxicity, flammability and disposal problems associated with the scintillators of traditional formulation.The increasing popularity of the new solvents in the realization of experimental set-ups of various degrees of size and complexity implies the need of a thorough study and characterization of the features of the corresponding scintillation mixtures, with the aim to approach eventually a level of understanding similar to that, very accurate, achieved throughout many years of research for the scintillators realized with conventional solvents.In this general context, aim of this work is to illustrate the results of the fluorescence decay time and pulse shape discrimination measurements carried out on a set of scintillation mixtures realized using two of such novel solvents, i.e., linear alkylbenzene (LAB) and di-isopropylnaphthalene (DIN). The measurements have been performed either under particle or UV excitation of the scintillating solutions, which permitted to unravel the features both of the fast component and of the long tail forming the entire scintillation pulse.Moreover, the particle characterization via ? or ? excitation allows also predicting the ??? pulse shape discrimination capability of the mixtures, a property of paramount significance for applications focused on the increasingly important field of low background detectors.

Lombardi, Paolo; Ortica, Fausto; Ranucci, Gioacchino; Romani, Aldo

2013-02-01

350

Beta-Gamma Coincidence Counting Using an Yttrium Aluminum Perovskit and Bismuth Germanate Phoswich Scintillator  

SciTech Connect

Abstract– Phoswich detectors (two scintillators attached to the same photomultiplier-tube) have been used in the past to measure either betas or gammas separately but were not used to measure beta-gamma coincidence signatures. These coincidence signatures are very important for the detection of many fission products and are exploited to detect four radioxenon isotopes using the Automated Radioxenon Sampler/Analyzer (ARSA) [1]. Previous PNNL work with a phoswich detector used a commercially available, thin disk of scintillating CaF2(Eu) and a 2” thick NaI(Tl) crystal in a phoswich arrangement. Studies with this detector measured the beta-gamma coincidence signatures from 133Xe, 214Pb and 214Bi [2]. This scintillator combination worked but was not a good match in scintillation light decay times, 940-ns for CaF2(Eu) and 230 ns for NaI(Tl). Additionally, a 6 mm thick quartz window was placed between the NaI(Tl) and the CaF2 to ensure a hermetic seal for the NaI(Tl) crystal . This dead layer significantly reduced the detection probability of the low energy x-rays and gammas that are part of the coincidence signatures for 214Pb, 214Bi and the radioxenons. Further research showed that Yttrium aluminum perovskit (YAP) and bismuth germanate (BGO) have very good scintillation light characteristics and no hermetic seal requirements. The 27-ns scintillation light decay time of YAP and the 300-ns decay time for BGO are a good match between fast and slow light output. The scintillation light output was measured using XIATM digital signal processing readout electronics, and the fast (YAP) and slow (BGO) light components allowed discrimination between the beta and gamma contributions of the radioactive decays. In this paper we discuss the experimental setup and results obtained with this new phoswich detector and the applications beyond radioxenon gas measurements.

McIntyre, Justin I.; Schrom, Brian T.; Aalseth, Craig E.; Cooper, Matthew W.; Hayes, James C.; Heimbigner, Tom R.; Hossbach, Todd W.; Hubbard, Charles W.; Litke, Kevin E.; Ripplinger, Mike D.; Seifert, Carolyn E.; Suarez, Reynold

2006-02-27

351

Integrated readout of organic scintillator and ZnS:Ag/6LiF for segmented antineutrino detectors.  

SciTech Connect

Antineutrino detection using inverse beta decay conversion has demonstrated the capability to measure nuclear reactor power and fissile material content for nuclear safeguards. Current efforts focus on aboveground deployment scenarios, for which highly efficient capture and identification of neutrons is needed to measure the anticipated antineutrino event rates in an elevated background environment. In this submission, we report on initial characterization of a new scintillation-based segmented design that uses layers of ZnS:Ag/{sup 6}LiF and an integrated readout technique to capture and identify neutrons created in the inverse beta decay reaction. Laboratory studies with multiple organic scintillator and ZnS:Ag/{sup 6}LiF configurations reliably identify {sup 6}Li neutron captures in 60 cm-long segments using pulse shape discrimination.

Kiff, Scott D.; Reyna, David; Monahan, James; Bowden, Nathaniel S.

2010-11-01

352

Integrated readout of organic scintillator and ZnS:Ag/6LiF for segmented antineutrino detectors.  

SciTech Connect

Antineutrino detection using inverse beta decay conversion has demonstrated the capability to measure nuclear reactor power and fissile material content for nuclear safeguards. Current efforts focus on aboveground deployment scenarios, for which highly efficient capture and identification of neutrons is needed to measure the anticipated antineutrino event rates in an elevated background environment. In this submission, we report on initial characterization of a new scintillation-based segmented design that uses layers of ZnS:Ag/{sup 6}LiF and an integrated readout technique to capture and identify neutrons created in the inverse beta decay reaction. Laboratory studies with multiple organic scintillator and ZnS:Ag/{sup 6}LiF configurations reliably identify {sup 6}Li neutron captures in 60 cm-long segments using pulse shape discrimination.

Kiff, Scott D.; Reyna, David; Monahan, James (Drexel University, Philadelphia, PA); Bowden, Nathaniel S. (Lawrence Livermore National Laboratory, Livermore, CA)

2010-10-01

353

A semi-empirical Monte Carlo based model of the Detector Optical Gain of Nuclear Imaging scintillators  

NASA Astrophysics Data System (ADS)

This paper reports a theoretical model of the optical gain of single-crystal scintillators of Nuclear Imaging. The model described the generation, propagation and escape of scintillation light as function of thickness and absorbed gamma ray energy. The latter was calculated via Monte Carlo methods at various crystal depths. The energies of 140 keV, 364 keV and 512 keV were investigated. The adopted thickness and energy values cover the range utilized in nuclear medicine imaging. For the semi-empirical approach, theoretical results were compared to experimental data for photon energies of 140 keV and 364 keV and the model's optical parameters were determined by the trial and error method. The results rendered the calculation of the optimum crystal thickness per investigated gamma ray energy. The presented results could be useful in designing nuclear medicine imaging systems.

Nikolopoulos, D.; Kalyvas, N.; Valais, I.; Argyriou, X.; Vlamakis, E.; Sevvos, T.; Kandarakis, I.

2012-11-01

354

DETECTORS AND EXPERIMENTAL METHODS: Measurement of the neutron spectrum of a PuC source with a liquid scintillator  

Microsoft Academic Search

The neutron response function for a BC501A liquid scintillator (LS) has been measured using a series of monoenergetic neutrons produced by the p-T reaction. The proton energies were chosen such as to produce neutrons in the energy range of 1 to 20 MeV. The principles of the technique of unfolding a neutron energy spectrum by using the measured neutron response

Song-Lin Wang; Han-Xiong Huang; Xi-Chao Ruan; Xia Li; Jie Bao; Yang-Bo Nie; Qi-Ping Zhong; Zu-Ying Zhou; Xiang-Zhong Kong

2009-01-01

355

AMoRE experiment: a search for neutrinoless double beta decay of 100Mo isotope with 40Ca100MoO4 cryogenic scintillation detector  

NASA Astrophysics Data System (ADS)

AMoRE (Advanced Mo based Rare process Experiment) collaboration is going to use calcium molybdate crystals as cryogenic scintillation detector in a search for neutrinoless DBD of 100Mo isotope. Simultaneous detection of phonons and light will be used to reject internal background. A FWHM resolution of 0.2% in the phonon channel has been achieved with a 0.5 cm3 crystal. Several 40Ca100MoO4 crystals (? 0.5 kg) have been developed from enriched 100Mo and depleted 40Ca materials. The light yield of these crystals has been shown to be comparable with reference CaMoO4 scintillators for temperatures ranging down to 8 K. The content of dangerous radioisotopes in the crystals is under measurement. The projected sensitivity of the experiment for a 250 kg × years exposure is lim T1/2 ~ 3 × 1026 years, which corresponds to the effective Majorana neutrino mass langlemvrangle ~ 0.02 - 0.06 eV.

Bhang, H.; Boiko, R. S.; Chernyak, D. M.; Choi, J. H.; Choi, S.; Danevich, F. A.; Efendiev, K. V.; Enss, C.; Fleischmann, A.; Gangapshev, A. M.; Gastaldo, L.; Gezhaev, A. M.; Hwang, Y. S.; Jiang, H.; Kang, W. G.; Kazalov, V. V.; Khanbekov, N. D.; Kim, H. J.; Kim, K. B.; Kim, S. K.; Kim, S. C.; Kim, Y. D.; Kim, Y. H.; Kobychev, V. V.; Kornoukhov, V. N.; Kuzminov, V. V.; Mokina, V. M.; Lee, H. S.; Lee, J. I.; Lee, J. M.; Lee, K. B.; Lee, M. J.; Lee, M. K.; Lee, S. J.; Li, J.; Li, X.; Myung, S. S.; Nikolaiko, A. S.; Olsen, S.; Panasenko, S. I.; Park, H.; Poda, D. V.; Podviyanuk, R. B.; Polischuk, O. G.; Polozov, P. A.; Ratkevich, S. S.; Satou, Y.; So, J. H.; Tanida, K.; Tretyak, V. I.; Yakimenko, S. P.; Yue, Q.; Yuryev, Y.

2012-07-01

356

Study of n-? discrimination for 0.4-1 MeV neutrons using the zero-crossing method with a BC501A liquid scintillation detector  

NASA Astrophysics Data System (ADS)

An experimental system aimed at n-? discrimination using the zero-crossing method with a varphi3? × 2? BC501A liquid scintillation detector was established and tested with an Am-Be neutron source. Two-dimensional plots of energy versus zero-crossing time were obtained. The quality of n-? discrimination was checked by the figure-of-merit (FOM), the neutron peak-to-valley ratio, and the proportion of leaked neutrons over all neutron events. The performance of n-? discrimination in terms of FOM was compared with previous work done by other groups. The n-? discrimination in four different energy regions with an interval of 0.1 MeV between 0.3 MeV and 0.7 MeV was studied, and the results indicate that the n-? discrimination threshold can go down to 0.4 MeV.

Chen, Yong-Hao; Lei, Jia-Rong; Zhang, Xiao-Dong; An, Li; Zheng, Pu; Wang, Xin-Hua; Zhu, Chuan-Xin; He, Tie

2013-04-01

357

Well-type scintillation assembly  

Microsoft Academic Search

A scintillation detector assembly is described which employs a scintillation phosphor such as a thallium activated sodium iodide crystal, wherein a blind hole is machined in the crystal to improve the efficiency of measuring the degradation rate of a radioactive material placed therein. The performance of the assembly is defined by the energy resolution of the radiation emanating from the

M. R. Farukhi; G. A. Mataraza; O. D. Wimer

1978-01-01

358

Experimental response function of NaI(Tl) scintillation detector for gamma photons and tomographic measurements for defect detection  

Microsoft Academic Search

The response function of gamma detector is an important factor for spectrum analysis because some photons and secondary electrons may escape the detector volume before fully depositing their energy, of course destroys the ideal delta function response. An inverse matrix approach, for unfolding of observed pulse-height distribution to a true photon spectrum, is used for construction of experimental response function

Amandeep Sharma; Karamjit Singh; Bhajan Singh; B. S. Sandhu

2011-01-01

359

Low-cost extruded plastic scintillator  

Microsoft Academic Search

Motivated by a need for lower cost plastic scintillation detectors, we have tested commercially available polystyrene pellets in order to produce scintillating materials that can be extruded into various shapes. Selection of the raw materials is discussed. Two techniques are described that add wavelength shifting dopants to polystyrene pellets and extrude plastic scintillating bars using these materials. Data on light

Anna Pla-Dalmau; Alan D. Bross; Kerry L. Mellott

2001-01-01

360

Scintillating glass fiber neutron sensors.  

National Technical Information Service (NTIS)

Cerium-doped lithium-silicate glass fibers have been developed at Pacific Northwest Laboratory (PNL) for use as thermal neutron detectors. By using highly-enriched (sup 6) Li , these fibers efficiently capture thermal neutrons and produce scintillation li...

K. H. Abel R. J. Arthur M. Bliss

1994-01-01

361

Scintillator fiber optic long counter  

DOEpatents

A flat response position sensitive neutron detector capable of providing neutron spectroscopic data utilizing scintillator fiber optic filaments embedded in a neutron moderating housing having an open end through which neutrons enter to be detected.

McCollum, Tom (Sterling, VA); Spector, Garry B. (Fairfax, VA)

1994-01-01

362

Scintillator fiber optic long counter  

DOEpatents

A flat response position sensitive neutron detector capable of providing neutron spectroscopic data utilizing scintillator fiber optic filaments embedded in a neutron moderating housing having an open end through which neutrons enter to be detected is described. 11 figures.

McCollum, T.; Spector, G.B.

1994-03-29

363

An evaluation of the response of a scintillation detector for estimating the radionuclide composition of a contaminated cloud.  

PubMed

We have made Monte Carlo calculations of the scintillation spectrometer response for the photon field from a cloud of contaminated air after selected scenarios of a nuclear power plant accident. Calculations (using MCNP5 code-X-5 Monte Carlo Team, 2005) were performed for 36 main energy lines of the expected radionuclides. The evaluated spectra enable us to simulate real composite spectra and their evolution in time, and to assess the applicability of a specific spectrometry system for a semi-qualitative and semi-quantitative analysis of the composition of the cloud. PMID:19897376

Kluson, J; Cechák, T; Kuca, P; H?lka, J

2009-10-17

364

Characterization of Phoswich Well Detectors for Radioxenon Monitoring  

SciTech Connect

Devices to measure the amount of radioactive xenon in the atmosphere have been installed in several locations around the world as part of the International Monitoring System to detect nuclear weapons testing. These devices extract small samples of xenon from large volumes of air and look for characteristic radioxenon isotopes emitting beta and gamma radiation in coincidence. To detect these coincidences, they currently employ a complex system of separate beta and gamma detectors which is very sensitive, but which requires careful calibration and gain matching of several detectors and photomultiplier tubes to achieve desired detection limits. An alternative to separate beta and gamma detectors is the use of a single phoswich detector in which beta-gamma coincidences are detected by pulse shape analysis. The phoswich detector consists of a plastic scintillator (absorbing betas) optically coupled to a CsI(Tl) scintillator (absorbing gammas) and thus requires only a single photomultiplier tube and electronics readout channel, greatly simplifying setup and calibration. In this paper, we present the results from an experimental evaluation of two phoswich well detector prototypes, including energy resolution, 2 D beta/gamma energy histograms from a variety of test sources, and background count rates. From these measurements, we derive detector properties such as coincidence detection efficiency, background rejection and the ability to separate beta only, gamma only, and coincidence events. We will further discuss setup and calibration procedures and compare them to those for existing detector systems.

Hennig, Wolfgang; Tan, Hui; Warburton, William K.; Fallu-Labruyere, A.; Sabourov, K.; McIntyre, Justin I.; Cooper, Matthew W.; Gleyzer, A.

2007-09-01

365

Simulations of Extensive Air Showers for the Estimation of the Number of Photoelectrons of a Setup of P. Auger Fluorescence Detector  

NASA Astrophysics Data System (ADS)

The efficiency of a pixel detector using optical UV filters is determined in this work. Based on the Auger fluorescence detector geometry, we have calculated the overall efficiency of the pixel detector using an appropriate method that takes into account the particular spectral functions and the dependence on the angle of incidence of the optical filter used. Assuming extensive air shower (EAS) events developed with various inclinations generated by AIRES code, we calculated the number of electrons and positrons produced during the development of the EAS's. The detection efficiency of the pixel detector is taken into account in estimating the recorded signal (number of photoelectrons) for two sets of EAS simulations, corresponding to protons and iron nuclei, as primary particles.

Geranios, A.; Fokitis, E.; Maltezos, S.; Patrinos, K.; Rozaki-Mavrouli, H.

366

X-ray and gamma-ray response of a 2?×2? LaBr3:Ce scintillation detector  

NASA Astrophysics Data System (ADS)

Advances in material growth techniques have recently made large volume LaBr3:Ce crystals commercially available. These scintillators are currently being assessed by ESA for use as remote sensing gamma-ray spectrometers on future planetary missions. In addition to their superior scintillation properties (high light output, fast time response and good stopping power), they offer significant benefits when designing gamma-ray detection systems for resource-limited spacecraft—not only in terms of resources but also in terms of reliability and robustness. We present the results of an investigation into the gamma-ray detection properties of a 2?×2? LaBr3:Ce crystal, characterized using radioactive sources over the energy range 14 3220 keV. The response of the crystal was found to be largely linear over the upper 95% of the dynamic range, the deviations at lower energies can be attributed to the shortcomings of the PMT. Compared to smaller volume crystals, no substantial degradation in light output, or alternately, energy resolution has been observed. For example, at 662 keV, an energy resolution of 3% FWHM was measured. Experiments with monoenergetic protons show that they create approximately half the light output of gamma-rays.

Quarati, F.; Bos, A. J. J.; Brandenburg, S.; Dathy, C.; Dorenbos, P.; Kraft, S.; Ostendorf, R. W.; Ouspenski, V.; Owens, Alan

2007-04-01

367

Digital discrimination of neutrons and ? rays with organic scintillation detectors in an 8-bit sampling system using frequency gradient analysis  

NASA Astrophysics Data System (ADS)

The feasibility of using frequency gradient analysis (FGA), a digital method based on Fourier transform, to discriminate neutrons and ? rays in the environment of an 8-bit sampling system has been investigated. The performances of most pulse shape discrimination methods in a scintillation detection system using the time-domain features of the photomultiplier tube anode signal will be lower or non-effective in this low resolution sampling system. However, the FGA method using the frequency-domain features of the anode signal exhibits a strong insensitivity to noise and can be used to discriminate neutrons and ? rays in the above sampling system. A detailed study of the quality of the FGA method in BC501A liquid scintillators is presented using a 5 G samples/s 8-bit oscilloscope and a 14.1 MeV neutron generator. A comparison of the discrimination results of the time-of-flight and conventional charge comparison (CC) methods proves the applicability of this technique. Moreover, FGA has the potential to be implemented in current embedded electronics systems to provide real-time discrimination in standalone instruments.

Yang, Jun; Luo, Xiao-Liang; Liu, Guo-Fu; Lin, Cun-Bao; Wang, Yan-Ling; Hu, Qing-Qing; Peng, Jin-Xian

2012-06-01

368

Development of large-volume, high-resolution tracking detectors based on capillaries filled with liquid scintillator  

NASA Astrophysics Data System (ADS)

Searches for the decay of short-lived particles require real time, high-resolution tracking in active targets, which in the case of neutrino physics should be of large volume. The possibility of achieving this by using glass capillaries filled with organic liquid scintillator is being investigated in the framework of the CHORUS experiment at CERN. In this paper, after outlining the application foreseen, advances in the tracking technique are discussed and results from tests are reported. An active target of dimensions 180 × 2 × 2 cm3 has been assembled from capillaries with 20 ?m diameter pores. The readout scheme currently in operation allows the reading of ~ 5 × 105 channels using a single chain of image intensifiers having a resolution of ? ~ 20 ?m. Following the development of new liquid scintillators and purification methods an attenuation length of ~ 3 m has been obtained. This translates into a hit density of 3.5 per mm for a minimum-ionizing particle that crosses the active target at a distance of 1 m from the readout end.

Buontempo, S.; Fabre, J.-P.; Frenkel, A.; Galeazzi, F.; Golovkin, S.; Gregoire, G.; Harrison, K.; Hoepfner, K.; Konijn, J.; Kozarenko, E.; Kreslo, I.; Kushnirenko, A.; Martellotti, G.; Mazzoni, M. A.; Medvedkov, A.; Michel, L.; Mommaert, C.; Mondardini, M. R.; Panman, J.; Penso, G.; Petukhov, Y.; Siegmund, W. P.; Strack, R.; Tyukov, V.; Vasilchenko, V.; Vilain, P.; Wilquet, G.; Winter, K.; Wong, H.; Zymin, K.

1995-02-01

369

Composite CaWO{sub 4} Detectors for the CRESST-II Experiment  

SciTech Connect

CRESST-II, standing for Cryogenic Rare Events Search with Superconducting Thermometers phase II, is an experiment searching for Dark Matter. In the LNGS facility in Gran Sasso, Italy, a cryogenic detector setup is operated in order to detect WIMPs by elastic scattering off nuclei, generating phononic lattice excitations and scintillation light. The thermometers used in the experiment consist of a tungsten thin-film structure evaporated onto the CaWO{sub 4} absorber crystal. The process of evaporation causes a decrease in the scintillation light output. This, together with the need of a big-scale detector production for the upcoming EURECA experiment lead to investigations for producing thermometers on smaller crystals which are glued onto the absorber crystal. In our Run 31 we tested composite detectors for the first time in the Gran Sasso setup. They seem to produce higher light yields as hoped and could provide an additional time based discrimination mechanism for low light yield clamp events.

Kiefer, M.; Angloher, G.; Bavykina, I.; Hauff, D.; Huff, P.; Lang, R. F.; Pantic, E.; Petricca, F.; Proebst, F.; Schaeffner, K.; Schmaler, J.; Seidel, W.; Stodolsky, L. [Max-Planck-Institut fuer Physik, Foehringer Ring 6, D-80805 Muenchen (Germany); Bauer, M.; Deuter, G.; Jochum, J.; Kimmerle, M.; Rottler, K.; Sailer, C.; Scholl, S. [Eberhard-Karls-Universitaet Tuebingen, D-72076 Tuebingen (Germany)] (and others)

2009-12-16

370

Monte-Carlo simulation of a compact gamma-ray detector using wavelength-shifting fibers coupled to a YAP scintillation crystal  

NASA Astrophysics Data System (ADS)

The production and transportation of fluorescent light produced in wavelength-shifting fibers (WSFs) coupled to YAP scintillation crystal is simulated using the GEANT4 codes. An advantage of the wavelength-shifting fiber readout technique over a direct readout with a position-sensitive photo-sensor is the reduced requirement for position sensitive photomultiplier tube photocathode area. With this gamma-ray detector, the gamma camera is small and flexible and has larger effective field of view and low cost. Simulation results show that a) a mean 12 of photons per 59.5 keV gamma ray interaction is produced in the WSF located nearest to the incident gamma ray, and a spatial resolution of 3.6 mm FWHM is obtained, b) a mean 27 of photons per 140 keV gamma ray interaction is produced and a spatial resolution of 3.1 mm FWHM is obtained. Results demonstrate the feasibility of this concept of a compact gamma-ray detector based on wavelength-shifting fibers readout. However, since the very low photoelectron levels, it is very important to use a photon counting device with good single photo-electron response to readout the WSFs. Supported by National Nature Science Foundation of China (10275063)

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

2008-05-01

371

Coping with Plastic Scintillators in Nuclear Safeguards.  

National Technical Information Service (NTIS)

Plastic scintillators offer several advantages for nuclear safeguards research and technology to those who design, assemble, encapsulate, and calibrate detectors from raw materials that are commercially available. These large, inexpensive detectors have g...

P. E. Fehlau G. S. Brunson

1982-01-01

372

Nanophosphor composite scintillator with a liquid matrix  

DOEpatents

An improved nanophosphor scintillator liquid comprises nanophosphor particles in a liquid matrix. The nanophosphor particles are optionally surface modified with an organic ligand. The surface modified nanophosphor particle is essentially surface charge neutral, thereby preventing agglomeration of the nanophosphor particles during dispersion in a liquid scintillator matrix. The improved nanophosphor scintillator liquid may be used in any conventional liquid scintillator application, including in a radiation detector.

McKigney, Edward Allen (Los Alamos, NM); Burrell, Anthony Keiran (Los Alamos, NM); Bennett, Bryan L. (Los Alamos, NM); Cooke, David Wayne (Santa Fe, NM); Ott, Kevin Curtis (Los Alamos, NM); Bacrania, Minesh Kantilal (Los Alamos, NM); Del Sesto, Rico Emilio (Los Alamos, NM); Gilbertson, Robert David (Los Alamos, NM); Muenchausen, Ross Edward (Los Alamos, NM); McCleskey, Thomas Mark (Los Alamos, NM)

2010-03-16

373

Extruding plastic scintillator at Fermilab  

SciTech Connect

An understanding of the costs involved in the production of plastic scintillators and the development of a less expensive material have become necessary with the prospects of building very large plastic scintillation detectors. Several factors contribute to the high cost of plastic scintillating sheets, but the principal reason is the labor-intensive nature of the manufacturing process. In order to significantly lower the costs, the current casting procedures had to be abandoned. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. This concept was tested and high quality extruded plastic scintillator was produced. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. This paper will discuss the characteristics of extruded plastic scintillator and its raw materials, the different manufacturing techniques and the current R&D program at Fermilab.

Anna Pla-Dalmau; Alan D. Bross; Victor V. Rykalin

2003-10-31

374

Measurement of the {sup 8}B solar neutrino flux with the KamLAND liquid scintillator detector  

SciTech Connect

We report a measurement of the neutrino-electron elastic scattering rate from {sup 8}B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5-MeV analysis threshold is 1.49 {+-} 0.14(stat) {+-} 0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a {sup 8}B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77 {+-} 0.26(stat) {+-} 0.32(syst) x10{sup 6} cm{sup -2}s{sup -1}. The analysis threshold is driven by {sup 208}Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic {sup 11}Be. The measured rate is consistent with existing measurements and with standard solar model predictions which include matter-enhanced neutrino oscillation.

Abe, S.; Furuno, K.; Gando, A.; Gando, Y.; Ichimura, K.; Ikeda, H.; Kibe, Y.; Kimura, W.; Kishimoto, Y.; Minekawa, Y.; Mitsui, T.; Morikawa, T.; Nagai, N.; Nakajima, K.; Nakamura, M.; Narita, K.; Shimizu, I.; Shimizu, Y.; Shirai, J.; Suekane, F. [Research Center for Neutrino Science, Tohoku University, Sendai 980-8578 (Japan)

2011-09-15

375

Development of a Simple Positron Age-Momentum Setup  

NASA Astrophysics Data System (ADS)

A positron age-momentum setup that uses NIM Bin electronic modules and a conventional multichannel analyzer (MCA) is described. The essential idea is to accumulate a Doppler broadened spectrum (sensitive to the annihilation electron momentum) using a high purity Germanium detector in coincidence with a BaF2 scintillation counter, which also serves as the stop signal in a conventional positron lifetime setup. The MCA that collects the Doppler spectrum is gated by a selected region of the lifetime spectrum. Thus we can obtain Doppler broadening spectra as a function of positron lifetime: an age-momentum spectrum. The apparatus has been used so far to investigate a ZnO sample where the size of different vacancy trapping sites may affect the positron lifetime and the Doppler broadening spectrum. We are also looking at polymer and rubber carbon-black composite samples where differences in the Doppler spectrum may arise from positron trapping or positronium formation in the samples. Correction for background and contribution from the positron source itself to the Doppler spectrum will be discussed.

Sheffield, Thomas; Quarles, C. A.

2009-04-01

376

Indirect flat-panel detector with avalanche gain: Fundamental feasibility investigation for SHARP-AMFPI (scintillator HARP active matrix flat panel imager)  

SciTech Connect

An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The final electronic image is read out using an active matrix array of thin film transistors (TFT). We call the proposed detector SHARP-AMFPI (scintillator HARP active matrix flat panel imager). The advantage of the SHARP-AMFPI is its programmable gain, which can be turned on during low dose fluoroscopy to overcome electronic noise, and turned off during high dose radiography to avoid pixel saturation. The purpose of this paper is to investigate the important design considerations for SHARP-AMFPI such as avalanche gain, which depends on both the thickness d{sub Se} and the applied electric field E{sub Se} of the HARP layer. To determine the optimal design parameter and operational conditions for HARP, we measured the E{sub Se} dependence of both avalanche gain and optical quantum efficiency of an 8 {mu}m HARP layer. The results were used in a physical model of HARP as well as a linear cascaded model of the FPI to determine the following x-ray imaging properties in both the avalanche and nonavalanche modes as a function of E{sub Se}: (1) total gain (which is the product of avalanche gain and optical quantum efficiency); (2) linearity; (3) dynamic range; (4) gain nonuniformity resulting from thickness nonuniformity; and (5) effects of direct x-ray interaction in HARP. Our results showed that a HARP layer thickness of 8 {mu}m can provide adequate avalanche gain and sufficient dynamic range for x-ray imaging applications to permit quantum limited operation over the range of exposures needed for radiography and fluoroscopy.

Zhao Wei; Li Dan; Reznik, Alla; Lui, B.J.M.; Hunt, D.C.; Rowlands, J.A.; Ohkawa, Yuji; Tanioka, Kenkichi [Department of Radiology, State University of New York at Stony Brook, L-4, 120 Health Sciences Center Stony Brook, New York 11793-8460 (United States); Imaging Research, Sunnybrook and Women's Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5 (Canada); Advanced Imaging Devices Research Division, Science and Technical Research Laboratories, Japan Broadcasting Corporation, 1-10-11 Kinuta, Setagaya-ku, Tokyo 157-8510 (Japan)

2005-09-15

377

The ultimate solar neutrino detector: Simultaneous detection of light and phonons in a fast scintillator made of single crystals of an indium compound and cooled to very low temperature  

NASA Astrophysics Data System (ADS)

Real time detection of low energy solar neutrinos remains a technical challenge. Progress has been made on scintillating single crystals of indium compounds. Cerium doping has been successfully implemented by a French group (Talence-Lyon-Annecy Collaboration). Since Ce3+ fluorescence is expected to remain fast at very low temperature, luminescence can be combined with phonon detection to improve energy resolution and localization, which are crucial for background rejection. Devices based on superconducting tunnel junctions may provide a read-out sensitive to the light strobe followed by the delayed pulse of phonons. Such a detector would operate at 3He temperatures (T ap; 350 mK). Alternatives to develop solar neutrino detectors, as well as other applications of low temperature scintillation, are briefly discussed.

Gonzalez-Mestres, L.

1992-07-01

378

Set-up of a passive Bonner sphere system for neutron spectrometry at mixed fields with predominant photon component based on activation detector.  

PubMed

A passive Bonner sphere system (BSS), based on thermal neutron activation detectors, was developed to perform neutron spectrometry in pulsed and very intense (n-gamma) fields with predominant photon component, as those produced by high energy (>10 MV) medical linear electron accelerators. In this paper, a description of the new system is presented together with an experimental characterisation of a portable Sodium Iodide (NaI) detector and a fixed high-purity Germanium one, both used to measure the induced gamma-activity of the activated materials, respectively, in situ and in the laboratory. The choice of the activated materials is justified according to pre-established practical considerations and physical criteria. The response functions of the entire passive BSS were calculated using the MCNPX code. A preliminary experimental validation with a bare (252)Cf source is given as well. PMID:17513860

Amgarou, K; Lacoste, V; Muller, H; Fernández, F

2007-05-18

379

Optical fiber readout of scintillator arrays using a multi-channel PMT: A high resolution PET detector for animal imaging  

SciTech Connect

The authors report the results from a new high resolution gamma ray imaging detector designed for use in a positron emission tomography (PET) system dedicated to small animal imaging. The detectors consist of an 8 x 8 array of 2 x 2 x 10 mm bismuth germanate (BGO) crystals coupled by 2 mm diameter double clad optical fibers to a 64 pixel multi-channel photomultiplier tube (MC-PMT). A charge division readout board is used to convert the 64 output channels into four position sensitive signals which determine the crystal of interaction. Measurements with a pair of these detectors demonstrate an intrinsic spatial resolution of 1.4 mm, a coincidence timing resolution of 15 ns and an energy resolution ranging between 35 and 60%. Based on these encouraging results, the design for a dedicated animal PET tomograph is proposed and simulations of this system project a reconstructed resolution of less than 2 mm within a 5 cm diameter transaxial field of view.

Cherry, S.R.; Shao, Y.; Siegel, S.; Silverman, R.W.; Mumcuoglu, E.; Meadors, K.; Phelps, M.E. [UCLA School of Medicine, Los Angeles, CA (United States)

1996-06-01

380

Evaluation of moderately cooled pure NaI as a scintillator for position-sensitive PET detectors  

SciTech Connect

A new evaluation of pure NaI has been performed to determine if moderate cooling would lead to better performance than that of existing, activated NaI(Tl) position-sensitive detectors, particularly at high countrates. Using a freezer, an initial effort was performed to cool the crystal assembly to {minus}90 C (183 K). At this temperature, pure NaI has a decay constant of 35 nsec, a light output which is about 20% that of room temperature NaI(Tl), and an energy resolution of 15%. For the PET applications the signal of room temperature (25 C) NaI(Tl) is normally pulse clipped, reducing the light output to 40% of the unclipped signal and yielding an energy resolution of 10.5%. Since the long decay of NaI(Tl) causes it to suffer more significantly than pure NaI from pre-pulse pileup, the difference in energy resolution between the two crystals at high countrates will be reduced. Also, a significantly shorter trigger deadtime with pure NaI will lead to a reduction in coincidence deadtime losses in PET. Computer simulations of large-area crystals operating at high countrates have been performed to quantify their trigger deadtime behavior and position resolution as a function of light output and pulse decay time. Having gained experience with the practical issues of cooling large crystals, measurements of position resolution have been performed with a NaI bar detector of similar geometry to the NaI(Tl) detectors in use in the PENN-PET scanner.

Wear, J.A.; Karp, J.S.; Haigh, A.T.; Freifelder, R. [Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Radiology

1996-06-01

381

Segmented crystalline scintillators: empirical and theoretical investigation of a high quantum efficiency EPID based on an initial engineering prototype CsI(TI) detector.  

PubMed

Modern-day radiotherapy relies on highly sophisticated forms of image guidance in order to implement increasingly conformal treatment plans and achieve precise dose delivery. One of the most important goals of such image guidance is to delineate the clinical target volume from surrounding normal tissue during patient setup and dose delivery, thereby avoiding dependence on surrogates such as bony landmarks. In order to achieve this goal, it is necessary to integrate highly efficient imaging technology, capable of resolving soft-tissue contrast at very low doses, within the treatment setup. In this paper we report on the development of one such modality, which comprises a nonoptimized, prototype electronic portal imaging device (EPID) based on a 40 mm thick, segmented crystalline CsI(Tl) detector incorporated into an indirect-detection active matrix flat panel imager (AMFPI). The segmented detector consists of a matrix of 160 x 160 optically isolated, crystalline CsI(Tl) elements spaced at 1016 microm pitch. The detector was coupled to an indirect detection-based active matrix array having a pixel pitch of 508 microm, with each detector element registered to 2 x 2 array pixels. The performance of the prototype imager was evaluated under very low-dose radiotherapy conditions and compared to that of a conventional megavoltage AMFPI based on a Lanex Fast-B phosphor screen. Detailed quantitative measurements were performed in order to determine the x-ray sensitivity, modulation transfer function, noise power spectrum, and detective quantum efficiency (DQE). In addition, images of a contrast-detail phantom and an anthropomorphic head phantom were also acquired. The prototype imager exhibited approximately 22 times higher zero-frequency DQE (approximately 22%) compared to that of the conventional AMFPI (approximately 1%). The measured zero-frequency DQE was found to be lower than theoretical upper limits (approximately 27%) calculated from Monte Carlo simulations, which were based solely on the x-ray energy absorbed in the detector-indicating the presence of optical Swank noise. Moreover, due to the nonoptimized nature of this prototype, the spatial resolution was observed to be significantly lower than theoretical expectations. Nevertheless, due to its high quantum efficiency (approximately 55%), the prototype imager exhibited significantly higher DQE than that of the conventional AMFPI across all spatial frequencies. In addition, the frequency-dependent DQE was observed to be relatively invariant with respect to the amount of incident radiation, indicating x-ray quantum limited behavior. Images of the contrast-detail phantom and the head phantom obtained using the prototype system exhibit good visualization of relatively large, low-contrast features, and appear significantly less noisy compared to similar images from a conventional AMFPI. Finally, Monte Carlo-based theoretical calculations indicate that, with proper optimization, further, significant improvements in the DQE performance of such imagers could be achieved. It is strongly anticipated that the realization of optimized versions of such very high-DQE EPIDs would enable megavoltage projection imaging at very low doses, and tomographic imaging from a "beam's eye view" at clinically acceptable doses. PMID:16696482

Sawant, Amit; Antonuk, Larry E; El-Mohri, Youcef; Zhao, Qihua; Wang, Yi; Li, Yixin; Du, Hong; Perna, Louis

2006-04-01

382

Segmented crystalline scintillators: Empirical and theoretical investigation of a high quantum efficiency EPID based on an initial engineering prototype CsI(Tl) detector  

SciTech Connect

Modern-day radiotherapy relies on highly sophisticated forms of image guidance in order to implement increasingly conformal treatment plans and achieve precise dose delivery. One of the most important goals of such image guidance is to delineate the clinical target volume from surrounding normal tissue during patient setup and dose delivery, thereby avoiding dependence on surrogates such as bony landmarks. In order to achieve this goal, it is necessary to integrate highly efficient imaging technology, capable of resolving soft-tissue contrast at very low doses, within the treatment setup. In this paper we report on the development of one such modality, which comprises a nonoptimized, prototype electronic portal imaging device (EPID) based on a 40 mm thick, segmented crystalline CsI(Tl) detector incorporated into an indirect-detection active matrix flat panel imager (AMFPI). The segmented detector consists of a matrix of 160x160 optically isolated, crystalline CsI(Tl) elements spaced at 1016 {mu}m pitch. The detector was coupled to an indirect detection-based active matrix array having a pixel pitch of 508 {mu}m, with each detector element registered to 2x2 array pixels. The performance of the prototype imager was evaluated under very low-dose radiotherapy conditions and compared to that of a conventional megavoltage AMFPI based on a Lanex Fast-B phosphor screen. Detailed quantitative measurements were performed in order to determine the x-ray sensitivity, modulation transfer function, noise power spectrum, and detective quantum efficiency (DQE). In addition, images of a contrast-detail phantom and an anthropomorphic head phantom were also acquired. The prototype imager exhibited approximately 22 times higher zero-frequency DQE ({approx}22%) compared to that of the conventional AMFPI ({approx}1%). The measured zero-frequency DQE was found to be lower than theoretical upper limits ({approx}27%) calculated from Monte Carlo simulations, which were based solely on the x-ray energy absorbed in the detector--indicating the presence of optical Swank noise. Moreover, due to the nonoptimized nature of this prototype, the spatial resolution was observed to be significantly lower than theoretical expectations. Nevertheless, due to its high quantum efficiency ({approx}55%), the prototype imager exhibited significantly higher DQE than that of the conventional AMFPI across all spatial frequencies. In addition, the frequency-dependent DQE was observed to be relatively invariant with respect to the amount of incident radiation, indicating x-ray quantum limited behavior. Images of the contrast-detail phantom and the head phantom obtained using the prototype system exhibit good visualization of relatively large, low-contrast features, and appear significantly less noisy compared to similar images from a conventional AMFPI. Finally, Monte Carlo-based theoretical calculations indicate that, with proper optimization, further, significant improvements in the DQE performance of such imagers could be achieved. It is strongly anticipated that the realization of optimized versions of such very high-DQE EPIDs would enable megavoltage projection imaging at very low doses, and tomographic imaging from a 'beam's eye view' at clinically acceptable doses.

Sawant, Amit; Antonuk, Larry E.; El-Mohri, Youcef; Zhao Qihua; Wang Yi; Li Yixin; Du Hong; Perna, Louis [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48103 (United States); Saint Gobain Crystals, Newbury, Ohio 44065 (United States)

2006-04-15

383

Scintillator material  

DOEpatents

An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography. 4 figs.

Anderson, D.F.; Kross, B.J.

1994-06-07

384

Scintillator material  

DOEpatents

An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography.

Anderson, David F. (Batavia, IL); Kross, Brian J. (Aurora, IL)

1992-01-01

385

Scintillator material  

DOEpatents

An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography.

Anderson, David F. (Batavia, IL); Kross, Brian J. (Aurora, IL)

1994-01-01

386

Method of making a scintillator waveguide  

DOEpatents

The present invention is an apparatus for detecting ionizing radiation, having: a waveguide having a first end and a second end, the waveguide formed of a scintillator material wherein the therapeutic ionizing radiation isotropically generates scintillation light signals within the waveguide. This apparatus provides a measure of radiation dose. The apparatus may be modified to permit making a measure of location of radiation dose. Specifically, the scintillation material is segmented into a plurality of segments; and a connecting cable for each of the plurality of segments is used for conducting scintillation signals to a scintillation detector.

Bliss, Mary (West Richland, WA); Craig, Richard A. (West Richland, WA); Reeder, Paul L. (Richland, WA)

2000-01-01

387

hybrid\\scriptsize{{MANTIS}}: a CPU-GPU Monte Carlo method for modeling indirect x-ray detectors with columnar scintillators  

NASA Astrophysics Data System (ADS)

The computational modeling of medical imaging systems often requires obtaining a large number of simulated images with low statistical uncertainty which translates into prohibitive computing times. We describe a novel hybrid approach for Monte Carlo simulations that maximizes utilization of CPUs and GPUs in modern workstations. We apply the method to the modeling of indirect x-ray detectors using a new and improved version of the code \\scriptsize{{MANTIS}}, an open source software tool used for the Monte Carlo simulations of indirect x-ray imagers. We first describe a GPU implementation of the physics and geometry models in fast\\scriptsize{{DETECT}}2 (the optical transport model) and a serial CPU version of the same code. We discuss its new features like on-the-fly column geometry and columnar crosstalk in relation to the \\scriptsize{{MANTIS}} code, and point out areas where our model provides more flexibility for the modeling of realistic columnar structures in large area detectors. Second, we modify \\scriptsize{{PENELOPE}} (the open source software package that handles the x-ray and electron transport in \\scriptsize{{MANTIS}}) to allow direct output of location and energy deposited during x-ray and electron interactions occurring within the scintillator. This information is then handled by optical transport routines in fast\\scriptsize{{DETECT}}2. A load balancer dynamically allocates optical transport showers to the GPU and CPU computing cores. Our hybrid\\scriptsize{{MANTIS}} approach achieves a significant speed-up factor of 627 when compared to \\scriptsize{{MANTIS}} and of 35 when compared to the same code running only in a CPU instead of a GPU. Using hybrid\\scriptsize{{MANTIS}}, we successfully hide hours of optical transport time by running it in parallel with the x-ray and electron transport, thus shifting the computational bottleneck from optical to x-ray transport. The new code requires much less memory than \\scriptsize{{MANTIS}} and, as a result, allows us to efficiently simulate large area detectors.

Sharma, Diksha; Badal, Andreu; Badano, Aldo

2012-04-01

388

Scintillating glass fiber neutron senors  

Microsoft Academic Search

Cerium-doped lithium-silicate glass fibers have been developed at Pacific Northwest Laboratory (PNL) for use as thermal neutron detectors. By using highly-enriched ⁶ Li , these fibers efficiently capture thermal neutrons and produce scintillation light that can be detected at the ends of the fibers. Advantages of scintillating fibers over ³He or BFâ proportional tubes include flexibility in geometric configuration, ruggedness

K. H. Abel; R. J. Arthur; M. Bliss; D BRITE; R BRODZINSKI; R CRAIG; B GEELHOOD; D GOLDMAN; J GRIFFIN; R PERKINS

1994-01-01

389

Scintillation Counters  

NASA Astrophysics Data System (ADS)

Scintillators find wide use in radiation detection as the detecting medium for gamma/X-rays, and charged and neutral particles. Since the first notice in 1895 by Roentgen of the production of light by X-rays on a barium platinocyanide screen, and Thomas Edison's work over the following 2 years resulting in the discovery of calcium tungstate as a superior fluoroscopy screen, much research and experimentation have been undertaken to discover and elucidate the properties of new scintillators. Scintillators with high density and high atomic number are prized for the detection of gamma rays above 1 MeV; lower atomic number, lower-density materials find use for detecting beta particles and heavy charged particles; hydrogenous scintillators find use in fast-neutron detection; and boron-, lithium-, and gadolinium-containing scintillators are used for slow-neutron detection. This chapter provides the practitioner with an overview of the general characteristics of scintillators, including the variation of probability of interaction with density and atomic number, the characteristics of the light pulse, a list and characteristics of commonly available scintillators and their approximate cost, and recommendations regarding the choice of material for a few specific applications. This chapter does not pretend to present an exhaustive list of scintillators and applications.

Bell, Zane W.

390

Preliminary detector design ST862-prototype neutron detector.  

National Technical Information Service (NTIS)

The detection of fast neutrons has been accomplished with commercially available liquid scintillators in detectors. Liquid scintillators discriminate fast neutrons from gamma radiation by discarding pulses with short decay constants. However, pulse-timing...

S. D. Miller J. D. Affinito D. R. Sisk

1993-01-01

391

Scintillating glass fiber neutron senors  

SciTech Connect

Cerium-doped lithium-silicate glass fibers have been developed at Pacific Northwest Laboratory (PNL) for use as thermal neutron detectors. By using highly-enriched {sup 6} Li , these fibers efficiently capture thermal neutrons and produce scintillation light that can be detected at the ends of the fibers. Advantages of scintillating fibers over {sup 3}He or BF{sub 3} proportional tubes include flexibility in geometric configuration, ruggedness in high-vibration environments, and less detector weight for the same neutron sensitivity. This paper describes the performance of these scintillating fibers with regard to count rates, pulse height spectra, absolute efficiencies, and neutron/gamma discrimination. Fibers with light transmission lengths (1/e) of greater than 2 m have been produced at PNL. Neutron sensors in fiber form allow development of a variety of neutron detectors packaged in previously unavailable configurations. Brief descriptions of some of the devices already produced are included to illustrate these possibilities.

Abel, K.H.; Arthur, R.J.; Bliss, M.

1994-04-01

392

AMoRE: Collaboration for searches for the neutrinoless double-beta decay of the isotope of 100Mo with the aid of 40Ca100MoO4 as a cryogenic scintillation detector  

NASA Astrophysics Data System (ADS)

The AMoRE (Advanced Mo based Rare process Experiment) Collaboration is planning to employ 40Ca100MoO4 single crystals as a cryogenic Scintillation detector for studying the neutrinoless double-beta decay of the isotope 100Mo. A simultaneous readout of phonon and scintillation signals is performed in order to suppress the intrinsic background. The planned sensitivity of the experiment that would employ 100 kg of 40Ca100MoO4 over five years of data accumulation would be T {1/2/0 ? } = 3 × 1026 yr, which corresponds to values of the effective Majorana neutrino mass in the range of < m ? > ˜ 0.02-0.06 eV.

Khanbekov, N. D.

2013-09-01

393

A comparison of collimator geometries for imaging mixed radiation fields with fast liquid organic scintillators  

SciTech Connect

As a result of recent advances in digital pulse-shape discrimination methods it has become possible to image mixed fields (radiation environments compromising both neutrons and gamma rays) relatively quickly with a single, organic liquid 'fast' scintillator within a heavy metal collimator. The use of a liquid scintillator has significant benefits over other techniques for imaging radiation environments as the acquired data can be analysed to provide separate information about the gamma and neutron emissions from a source (or sources) in a single scan. The imaging resolution achieved is fundamentally related to the detector efficiency and to the collimator geometry. In this paper the impact of using two different geometries of tungsten collimator are compared experimentally and three different materials considered in the Monte Carlo simulation, in order to determine the optimum set-up for mixed-field imaging. The measurements were performed in the low-scatter facility of the National Physical Laboratory, Teddington. (authors)

Gamage, K. A. A.; Joyce, M. J. [Engineering Dept., Lancaster Univ., Lancaster, Lancashire, LA1 4YR (United Kingdom); Taylor, G. C. [Neutron Metrology Group, National Physical Laboratory, Teddington, Middlesex, TW11 0LW (United Kingdom)

2011-07-01

394

Polyimide-based scintillating thin films  

Microsoft Academic Search

The production procedure and the scintillation characteristics of thin polyimide films containing rhodamine B are reported. Fluorinated polyimide has been chosen as host matrix for its well known radiation hardness, in order to improve the lifetime of detector systems based on plastic thin film scintillators, 6FDA (4,4'-hertafluoroisopropylidene diphthalic anhydride) and DAB (diaminobenzophenone) have been used as polyimide precursor monomers. The

A. Quaranta; S. Carturan; G. Maggioni; P. M. Milazzo; U. Abbondanno; G. Della Mea; F. Gramegna; U. Pieri

2001-01-01

395

Fabrication and imaging characterization of high sensitive CsI(Tl) and Gd 2O 2S(Tb) scintillator screens for X-ray imaging detectors  

Microsoft Academic Search

Indirect-detection methods consisted of an X-ray converter and photodiode arrays are more widely used in medical diagnosis and industrial fields. Two major scintillation materials such as terbium-doped gadolinium oxysulfide(Gd2O2S:Tb, Gadox) and thallium-doped cesium iodide(CsI:Tl) are commonly used. In this work, Gadox screens were manufactured by particle in binder (PIB) layer method and CsI:Tl scintillator films with columnar structure were also

Bo Kyung Cha; Jong Yul Kim; Tae Joo Kim; Cheulmuu Sim; Gyuseong Cho

2010-01-01

396

Guitar Intonation & Setup  

NSDL National Science Digital Library

This PowerPoint document provides a basic introduction to guitar intonation and setup. The presentation covers standard tuning, installing the nut and strings, neck relief and intonation. The presentation also includes illustrative diagrams and photographs.

2011-11-01

397

Extruded Plastic Scintillator for MINERvA.  

National Technical Information Service (NTIS)

An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. Since po...

A. Pla-Dalmau A. D. Bross V. V. Rykalin B. M. Wood

2005-01-01

398

Gamma cameras with SDDs coupled to scintillators  

NASA Astrophysics Data System (ADS)

Silicon Drift Detectors (SDDs) have been recently employed as scintillation detectors for (gamma) -ray spectroscopy and imaging applications. With respect to conventional PMTs, these devices offer the higher quantum efficiency to the scintillation light, typical of a silicon detector. Moreover, thanks to the low value of output capacitance, a SDD is characterized by a lower electronics noise with respect to a conventional silicon photodiode. This feature allows a detector based on the CsI(Tl)-SDD architecture to reach high energy and position resolution in gamma detection. In this work we present the results obtained in the development of a first prototype of gamma detector for 1D position measurements and of a first prototype of small gamma camera for 2D position measurements, both detectors based on a single scintillator coupled to an array of SDDs.

Fiorini, Carlo; Longoni, Antonio; Perotti, Francesco; Labanti, Claudio; Kemmer, Josef; Lechner, Peter; Leutenegger, Paolo; Strueder, Lothar

2000-07-01

399

Neutron scintillators using wavelength shifting fibers  

Microsoft Academic Search

A proposed design for an optically-based, one-dimension scintillation detector to replace the gas-filled position-sensitive proportional counter currently used for a wide-angle neutron detector (WAND) at the high-Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) is presented. The scintillator, consisting of a mixture of ⁶LiF and ZnS(Ag) powders in an epoxy binder, is coupled to an array of

D. P. Hutchinson; V. C. Miller; J. A. Ramsey

1995-01-01

400

Coping with plastic scintillators in nuclear safeguards  

Microsoft Academic Search

Plastic scintillators offer several advantages for nuclear safeguards research and technology to those who design, assemble, encapsulate, and calibrate detectors from raw materials that are commercially available. These large, inexpensive detectors have good spatial uniformity and good high-energy gamma-ray response. Uniform light collection is obtained with a light pipe attached to a polished scintillator wrapped with aluminum foil. Best low-energy

P. E. Fehlau; G. S. Brunson

1983-01-01

401

Digital data acquisition setup for ?-gamma correlation experiment  

NASA Astrophysics Data System (ADS)

A new-generation digital signal processing-based acquisition setup has been successfully tested and used in an on-line experiment at the NSCL at MSU. The acquisition system is based on the new Pixie16 boards from XIA. The detection setup consisted of the SeGA array and silicon detectors. All the signals were read out through the Pixie16 boards. Details of the set-up and results from the test will be given.

Rajabali, M. M.; Grzywacz, R.; Liddick, S. N.; Bingham, C.; Darby, I.; Mazzocchi, C.; Rykaczewski, K.; Batchelder, J.; Baumann, T.; Ginter, T.; Mantica, P.; Karny, M.; Miernik, K.; Pfutzner, M.; Ilyushkin, S. V.; Wagner, J. A.; Krolas, W.

2007-04-01

402

Gamma-ray multiplicity and neutron resonance parameter measurements with the Dubna 4pi detector Romashka  

NASA Astrophysics Data System (ADS)

A set-up based on a 16-section NaI(Tl) scintillation detector has been created at the 500 m flight-path of the IBR-30 booster in Dubna. The total volume of the detector is 36 liters, and the geometric efficiency is 80 percent. This detector measures gamma-cascades from resolved neutron resonances to obtain gamma-multiplicity spectra from neutron capture events. The 10B loaded converter, positioned inside the detector, makes it possible to detect also neutron scattering events by measuring monoenergetic gamma- quanta from the 10B(n, (alpha) (gamma) ) reaction. Thus, the same detector simultaneously registers neutron capture and neutron scattering events in the target under identical conditions. This permits spins, neutron and radiative widths, and neutron strength functions of resonances, to be determined. Applications of the detector for gamma- multiplicity studies are presented in the example of several Hf, Sn and Sm isotopes.

Georgiev, G. P.; Panajotova, N. G.

1997-02-01

403

Simple setups for quantum games in optical networks  

Microsoft Academic Search

In this work, we propose two optical setups for two-players, non-zero and zero sum, quantum games in optical networks using light polarization of single-photon pulses, single-photon detectors and linear optical devices. The optical setups proposed can be easily implemented permitting a fast experimental realization of quantum games with present technology.

Rubens Viana Ramos; Paulo Benicio Melo de Sousa

2006-01-01

404

Simple setups for quantum games in optical networks  

Microsoft Academic Search

In this work, we propose two optical setups for two-players, non-zero and zero sum, quantum games in optical networks using light polarization of single-photon pulses, single-photon detectors and linear optical devices. The optical setups proposed can be easily implemented permitting a fast experimental realization of quantum games with present technology. PACS: 03.67.Dd

Rubens Viana; Ramos Paulo; Benício Melo de Sous

405

The Virtual Slice Setup  

PubMed Central

In an effort to design a simulation environment that is more similar to that of neurophysiology, we introduce a virtual slice setup in the NEURON simulator. The virtual slice setup runs continuously and permits parameter changes including changes to synaptic weights and time course and to intrinsic cell properties. The virtual slice setup permits shocks to be applied at chosen locations and activity to be sampled intra- or extracellularly from chosen locations. By default, a summed population display is shown during a run to indicate the level of activity and no states are saved. Simulations can run for hours of model time, therefore it is not practical to save all of the state variables which in any case are primarily of interest at discrete times when experiments are being run: the simulation can be stopped momentarily at such times to save activity patterns. The virtual slice setup maintains an automated notebook showing shocks and parameter changes as well as user comments. We demonstrate how interaction with a continuously running simulation encourages experimental prototyping and can suggest additional dynamical features such as ligand wash-in and wash-out – alternatives to typical instantaneous parameter change. The virtual slice setup currently uses event-driven cells and runs at approximately 2 minutes/hour on a laptop.

Lytton, William W; Neymotin, Samuel A; Hines, Michael L

2008-01-01

406

Preshower detector for ?+?- hadronic atom studies  

NASA Astrophysics Data System (ADS)

A preshower (PSh) detector has been prepared, tested and used at the CERN-DIRAC experiment [B. Adeva, et al., DIRAC proposal, CERN/SPSLC 95-1, SPSLC/P 284, 1995]. The aim of this experiment was to test some nonperturbative QCD predictions [J. Gasser, H. Leutwyler, Phys. Lett. B 125 (1983) 325; J. Gasser, H. Leutwyler, Ann. Phys. 158 (1984) 142; J. Gasser, H. Leutwyler, Nucl. Phys. B 250 (1985) 465; J. Bijnens, G. Colangelo, G. Ecker, J. Gasser, M.E. Sainio, Phys. Lett. B 374 (1996) 210] by measuring pionium (?+?- hadronic atom) lifetime. In this context the PSh detector, together with the Cherenkov detector, pursued to reject the background electron pairs in the region 1-4 GeV where the pion pairs from atom breakup were present. The technique used for pion/electron separation was to probe the electron shower development in the early formation stage in Pb converter. We have studied the dependence of the amplitude spectra on particle momentum and converter and scintillator thickness. The estimated electron rejection efficiency was better than 85% with a pion loss less than 5% for a preshower detector with Pb converter thickness wPb=2.5 cm and scintillator slab wSc=1 cm. The PSh track efficiency within the DIRAC setup has been measured with a global efficiency per arm better than 99%, slab efficiency per arm better than 96% and corresponding pair events efficiency per arm ˜99% and per slab ˜93%.

Pentia, M.; Ciocarlan, C.; Constantinescu, S.; Gugiu, M.; Caragheorgheopol, Gh.

2009-05-01

407

Background levels in the Borexino detector  

NASA Astrophysics Data System (ADS)

The Borexino detector, designed and constructed for sub-MeV solar neutrino spectroscopy, is taking data at the Gran Sasso Laboratory, Italy; since May 2007. The main physics objective of Borexino, based on elastic scattering of neutrinos in organic liquid scintillator, is the real time flux measurement of the 862keV mono-energetic neutrinos from 7Be, which set extremely severe radio-purity requirements in the detector's design and handling. The first year of continous data taking provide now evidence of the extremely low background levels achieved in the construction of the detector and in the purification of the target mass. Several pieces of analysis sense the presence of radioisotopes of the 238U and 232Th chains, of 85Kr and of 210Po out of equilibrium from other Radon daughters. Particular emphasis is given to the detection of the cosmic muon background whose angular distributions have been obtained with the outer detector tracking algorithm and to the possibility of tagging the muon-induced neutron background in the scintillator with the recently enhanced electronics setup.

D'Angelo, Davide; Wurm, Michael; Borexino Collaboration

2008-11-01

408

The use of energy information in plastic scintillator material  

Microsoft Academic Search

Plastic scintillator material is often used for gamma-ray detection in many applications due to its relatively good sensitivity\\u000a and cost-effectiveness compared to other detection materials. However, due to the dominant Compton scattering interaction\\u000a mechanism, full energy peaks are not observed in plastic scintillator spectra and isotopic identification is impossible. Typically\\u000a plastic scintillator detectors are solely gross count detectors. In some

James H. Ely; Kevin K. Anderson; Derrick J. Bates; Richard T. Kouzes; C. Lo Presti; Robert C. Runkle; Edward R. Siciliano; Dennis R. Weier

2008-01-01

409

Optimization of a Scintillator for the Measurement of Positrons from Trapped, Polarized ^37K  

NASA Astrophysics Data System (ADS)

Precision beta decay experiments can be used to test the Standard Model via their value of correlation parameters. The TRINAT collaboration is performing such an experiment using a source of polarized ^37K from a magneto optical trap. The momentum of an emitted positron will be detected using a Silicon strip detector backed by a plastic scintillator. The goal of my research was to optimize the readout of the scintillator by testing different experimental setups. The front face and sides of the scintillator and light guide were wrapped with various reflective materials to find which maximized the light output. We found that one layer of Teflon tape on the front face with a loose wrapping of 3M-ESR (Enhanced Spectral Reflector) on the sides was optimal. We then tested the position dependence of this detector by moving a collimated source of betas across the front face, showing only a (5.9 ± 0.5)% reduction in light collection at the edge compared to the center. The product of this work will be used in the upcoming TRINAT experiment measuring the beta asymmetry of ^37K.

France, Erin; Melconian, Dan

2011-10-01

410

Use of Stilbene Scintillator for gamma Spectrometry.  

National Technical Information Service (NTIS)

This report deals with the set-up and calibration of a scintillation gamma spectrometer with a single stilbene crystal, for measuring gamma spectra in the energy range from 0.5-10-MeV. The spectrometer discriminates between the measured gamma rays and the...

A. S. Makarious R. Megahid R. M. A. Maayouf

1978-01-01

411

Plastic scintillation dosimetry for radiation therapy: minimizing capture of Cerenkov radiation noise  

Microsoft Academic Search

Over the last decade, there has been an increased interest in scintillation dosimetry using small water-equivalent plastic scintillators, because of their favourable characteristics when compared with other more commonly used detector systems. Although plastic scintillators have been shown to have many desirable dosimetric properties, as yet there is no successful commercial detector system of this type available for routine clinical

A Sam Beddar; Natalka Suchowerska; Susan H Law

2004-01-01

412

A helical scintillating fiber hodoscope  

NASA Astrophysics Data System (ADS)

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 (2.5mm 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°<=/?<=72° and 0°<=/?<=360° in the lab frame. The detector length is 590mm, the inner diameter 161mm. Geometry and granularity of the hodoscope afford a position resolution of about 1.3mm. The detector design took into consideration a maximum of reliability and a minimum of maintenance. An LED array may be used for monitoring purposes.

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.

1999-07-01

413

Scintillator Cosmic Ray Super Telescope  

NASA Astrophysics Data System (ADS)

The Scintillator Cosmic Ray Super Telescope (SciCRST) is a new experiment to detect solar neutrons, and also it is expected to work as a muon and cosmic ray detector. The SciCRST consist of 14,848 plastic scintillator bars, and it will be installed at the top of Sierra Negra volcano, Mexico, 4580 m.a.s.l. We use a prototype, called as miniSciBar, to test the hardware and software of the final experiment. In this paper, we present the status and details of the experiment, and results of the prototype.

González, L. X.; Valdés-Galicia, J. F.; Matsubara, Y.; Nagai, Y.; Itow, Y.; Sako, T.; López, D.; Mitsuka, G.; Munakata, K.; Kato, C.; Yasue, S.; Kosai, M.; Tsurusashi, M.; Nakamo, Y.; Shibata, S.; Takamaru, H.; Kojima, H.; Tsuchiya, H.; Watanabe, K.; Koi, T.; Fragoso, E.; Hurtado, A.; Musalem, O.

2013-04-01

414

Magnetic fields and scintillator performance  

SciTech Connect

Experimental data have shown that the light output of a scintillator depends on the magnitude of the externally applied magnetic fields, and that this variation can affect the calorimeter calibration and possibly resolution. The goal of the measurements presented here is to study the light yield of scintillators in high magnetic fields in conditions that are similar to those anticipated for the LHC CMS detector. Two independent measurements were performed, the first at Fermilab and the second at the National High Magnetic Field Laboratory at Florida State University.

Green, D.; Ronzhin, A. [Fermi National Accelerator Lab., Batavia, IL (United States); Hagopian, V. [Florida State Univ., Tallahasse, FL (United States)

1995-06-01

415

Testing and Installation of a High Efficiency CsI Scintillator Array  

NASA Astrophysics Data System (ADS)

Experiments on neutron-rich nuclei have identified changes to the structure of nuclei far from stability. The Sweeper-MoNA- LISA facility at the National Superconducting Cyclotron Laboratory (NSCL), located at Michigan State University, is used for performing experiments on neutron-rich nuclei. Currently, these experiments are limited to the mass region below neon due to the resolution of the charged fragment detectors, which limit the isotope separation. The resolution of the system will be improved with changes to the setup, primarily due to a new scintillator array. The new array will consist of twenty-five sodium-doped CsI crystals arranged in a 5 x 5 configuration. The array will be used to measure the kinetic energy of charged fragments with energies in the GeV range. The improved resolution will allow experiments of unbound systems above neon. The testing and assembly of the detector array will be presented.

Viscariello, Natalie; Casarotto, Stuart; Frank, Nathan; Smith, Jenna; Thoennessen, Michael

2011-10-01

416

CARMA Correlator Graphical Setup  

NASA Astrophysics Data System (ADS)

CARMA Correlator Graphical Setup (CGS) is a Java tool to help users of the Combined Array for Research in Millimeter-wave Astronomy (CARMA) plan observations. It allows users to visualize the correlator bands overlaid on frequency space and view spectral lines within each band. Bands can be click-dragged to anywhere in frequency and can have their properties (e.g., bandwidth, quantization level, rest frequency) changed interactively. Spectral lines can be filtered from the view by expected line strength to reduce visual clutter. Once the user is happy with the setup, a button click generates the Python commands needed to configure the correlator within the observing script. CGS can also read Python configurations from an observing script and reproduce the correlator setup that was used. Because the correlator hardware description is defined in an XML file, the tool can be rapidly reconfigured for changing hardware. This has been quite useful as CARMA has recently commissioned a new correlator. The tool was written in Java by high school summer interns working in UMD's Laboratory for Millimeter Astronomy and has become an essential planning tool for CARMA PIs.

Wu, D.; Shaya, B.; Pound, M. W.

2011-07-01

417

Influence of sampling properties of fast-waveform digitizers on neutron?gamma-ray, pulse-shape discrimination for organic scintillation detectors  

NASA Astrophysics Data System (ADS)

One of the most important questions to be answered with regard to digital pulse-shape discrimination (PSD) systems based on organic scintillators is: What sampling properties are required for a fast-waveform digitizer used for digitizing neutron/gamma-ray pulses, while an accurate PSD is desired? Answering this question is the main objective of this paper. Specifically, the paper describes the influence of the resolution and sampling frequency of a waveform digitizer on the PSD performance of organic scintillators. The results presented in this paper are meant to help the reader choosing a waveform digitizer with appropriate bit resolution and sampling frequency. The results presented here show that a 12-bit, 250-MHz digitizer is a good choice for applications that require good PSD performance. However, when more accurate PSD performance is the main requirement, this paper presents PSD figures of merit to qualify the impact of further increasing either sampling frequency or resolution of the digitizer.

Flaska, Marek; Faisal, Muhammad; Wentzloff, David D.; Pozzi, Sara A.

2013-11-01

418

Fast Timing Measurements Using CeBr3 Scintillators  

NASA Astrophysics Data System (ADS)

Continued research in advancing scintillation detector technology for both basic and applied nuclear science has recently focused on novel alkali halides. One candidate, CeBr3, is capable of achieving 120 ps timing resolution, and has also been found to have an energy resolution on the order of 3-5%. In this work, the utility of CeBr3 detectors for research in basic nuclear physics has been investigated through fast-timing measurements of nanosecond and sub-nanosecond isomer half-lives. A t1/2=1.4 ns 2^+ state in ^152Sm was populated in the decay of a ^152Eu ?-calibration source, and a t1/2=537 ps 9/2^- state in ^177Hf in the decay of ^177Lu, produced through thermal neutron activation of a natural Lu foil in the UMass Lowell Research Reactor. Half-lives were measured using a multi-parameter data acquisition setup to obtain energy gated time spectra. Results of these measurements with CeBr3 detectors will be discussed in the context of next generation nuclear science research.

D'Olympia, N.; Lakshmi, S.; Chowdhury, P.; Jackson, E.; Glodo, J.; Shirwadkar, U.; Shah, K.

2011-10-01

419

Improved response matrices of Bonner sphere spectrometers with 6LiI scintillation detector and 3He proportional counter between 15 and 100 MeV  

Microsoft Academic Search

The neutron responses of Bonner sphere spectrometric systems with a 4 mm × 4 mm6LiI scintillator and with a 3He (32 mm diameter) proportional counter were calculated using the MCNP Monte Carlo code for the energy range 14.8 to 100 MeV. Calculated responses have been interpolated to evaluate the response matrix for both systems; data tables are available on diskette.

Vladimir Mares; Hans Schraube

1995-01-01

420

LabVIEW Data Acquisition for NE213 Neutron Detector  

SciTech Connect

A neutron spectroscopy system based on a NE213 liquid scintillation detector at the Stanford Linear Accelerator Center measures neutron energies from a few MeV up to 800 MeV. The neutrons are produced from the electron beam and target interactions. The NE 213 scintillator, coupled with a Photomultiplier Tube (PMT), detects and converts radiation into electric pulses for signal processing. Signals are processed through Nuclear Instrument Modules (NIM) and Computer Automated Measurement and Control (CAMAC) modules. The processed pulses are then fed into a CAMAC analog to digital converter module (ADC). The ADC classifies the incoming analog pulses into one of 2048 digital channels. Data acquisition (DAQ) software based on LabVIEW version 7.0 acquires and organizes data from the CAMAC ADC. The DAQ system presents a spectrum showing a relationship between pulse events and respective charge (digital channel number). Various photon sources, such as Co-60, Y-88, and AmBe-241, are used to calibrate the NE213 detector. For each source, a Compton edge and reference energy in MeVee is obtained, resulting in a calibration curve. This project is focused on the development of a DAQ system and control setup to collect and process information from a NE213 liquid scintillation detector. A manual is also created to document the process of the development and interpretation of the LabVIEW-based DAQ system.

Gangadharan, Dhevan

2003-09-23

421

SCINTILLATION SPECTROMETER  

DOEpatents

A portable scintillation spectrometer is described which is especially useful in radio-biological studies for determining the uptake and distribution of gamma -emitti