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1

Ionizations scintillation detectors  

NASA Astrophysics Data System (ADS)

A few references are made to factors which affect the energy resolution of proportional scintillation. The coupling of proportional or primary scintillation devices to photoionization detectors (PIPS chamber) is considered, both in the gas and liquid phases, and using the data available some information is given concerning its expected characteristics of energy, position and time resolution.

Policarpo, A. J. P. L.

2

Liquid capillary scintillation detectors  

SciTech Connect

The authors have been developing liquid-in-capillary detectors for tracking applications in high energy physics experiments. The detectors consist of glass capillaries of low refractive index filled with liquids of sufficiently high refractive index to produce an efficient waveguides. This paper describes recent work in which scintillating core liquids were prepared from the solvent 1-phenylnaphthalene and single solutes of selected fluorescent dyes.

Puseljic, D.; Baumbaugh, B.; Ditmire, T.; Kennedy, C.; Ruchti, R.; Ryan, J. (Notre Dame Univ., IN (USA). Dept. of Physics); Baumbaugh, A.; Knickerbocker, K. (Collimated Holes, Inc., Campbell, CA (USA)); Ellis, J.; Mead, R.; Swanson, D. (Collimated Holes, Inc., Campbell, CA (USA))

1990-04-01

3

Scintillation detector for carbon-14  

NASA Technical Reports Server (NTRS)

Detector consists of plastic, cylindrical double-wall scintillation cell, which is filled with gas to be analyzed. Thin, inner cell wall is isolated optically from outer (guard) scintillator wall by evaporated-aluminum coating. Bonding technique provides mechanical support to cell wall when device is exposed to high temperatures.

Knoll, G. F.; Rogers, W. L.

1971-01-01

4

Silicon photomultiplier characterization with a scintillating bar detector  

NASA Astrophysics Data System (ADS)

This paper describes a setup dedicated to the test of silicon photomultipliers interfaced to a scintillating bar detector. The main item of the setup is a scintillator bar tracker made of extruded bars, readout with wavelength shifter fibers: multiple configurations in terms of number of fibers and readout bar sides are available to test different readout approaches. This setup has been used to test the prototype SiPMs produced by FBK-irst which are characterized by a larger fill factor and photodetection efficiency with respect to standard devices. The SiPMs have been characterized in terms of efficiency, signal to noise ratio and mean photoelectron number using cosmic rays.

Berra, A.; Bonvicini, V.; Ferri, A.; Lietti, D.; Paternoster, G.; Piemonte, C.; Prest, M.; Vallazza, E.

2014-06-01

5

A Solid State Scintillation Detector  

Microsoft Academic Search

Efforts to substitute a solid state device for the usual photomultiplier of a scintillation type nuclear detector led to the photoconductive cell. Although extremely sensitive, cadmium sulfide responds slowly to low levels of light, and a technique providing improvement over several orders of magnitude failed to achieve measurement of individual pulses. In an integrating application, however, such a method makes

George E. Wilcox

1967-01-01

6

Unitary scintillation detector and system  

DOEpatents

The invention is a unitary alpha, beta, and gamma scintillation detector and system for sensing the presence of alpha, beta, and gamma radiations selectively or simultaneously. The scintillators are mounted in a light-tight housing provided with an entrance window for admitting alpha, beta, and gamma radiation and excluding ambient light from the housing. Light pulses from each scintillator have different decay constants that are converted by a photosensitive device into corresponding differently shaped electrical pulses. A pulse discrimination system identifies the electrical pulses by their respective pulse shapes which are determined by decay time. The identified electrical pulses are counted in separate channel analyzers to indicate the respective levels of sensed alpha, beta, and gamma radiations.

McElhaney, Stephanie A. (Oak Ridge, TN); Chiles, Marion M. (Knoxville, TN)

1994-01-01

7

Unitary scintillation detector and system  

DOEpatents

The invention is a unitary alpha, beta, and gamma scintillation detector and system for sensing the presence of alpha, beta, and gamma radiations selectively or simultaneously. The scintillators are mounted in a light-tight housing provided with an entrance window for admitting alpha, beta, and gamma radiation and excluding ambient light from the housing. Light pulses from each scintillator have different decay constants that are converted by a photosensitive device into corresponding differently shaped electrical pulses. A pulse discrimination system identifies the electrical pulses by their respective pulse shapes which are determined by decay time. The identified electrical pulses are counted in separate channel analyzers to indicate the respective levels of sensed alpha, beta, and gamma radiations. 10 figs.

McElhaney, S.A.; Chiles, M.M.

1994-05-31

8

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

9

Neutron position-sensitive scintillation detector  

DOEpatents

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

Strauss, Michael G. (Downers Grove, IL); Brenner, Raul (Woodridge, IL)

1984-01-01

10

Scintillating optical fiber trajectory detectors  

NASA Astrophysics Data System (ADS)

Measurements of attenuation in several types of plastic scintillating optical fibers give attenuation lengths varying from 0.8 to 1.5 m. By comparing attenuation as a function of wavelength in fibers of different thicknesses we infer the contributions to the attenuation from reflection losses and bulk scintillation losses. We find good agreement between these values and calculated estimates of attenuation in scintillator. We have also calculated the effective scintillation efficiency of small fibers relative to that of bulk scintillator (for scintillator with dimethyl POPOP as the waveshifting dye) for the two cases of optically coupled and decoupled fibers. Scintillating fiber ribbons made of 200 ?m square cross section fibers were exposed to relativistic iron nuclei at the LBL Bevalac, and positional resolution of 70 ?m was obtained. Relativistic neon and carbon were also detected in these ribbons. In a similar exposure of 100 ?m fibers to 50 MeV/n nitrogen nuclei at the NSCL cyclotron, Michigan State University, a positional resolution of about 50 ?m was obtained.

Davis, A. J.; Hink, P. L.; Binns, W. R.; Epstein, J. W.; Connell, J. J.; Israel, M. H.; Klarmann, J.; Vylet, V.; Kaplan, D. H.; Reucroft, S.

1989-03-01

11

The evolution of scintillating medical detectors  

NASA Astrophysics Data System (ADS)

The principle of scintillation detectors has been among the first realizations of radiation detectors. Despite ongoing attempts to switch to direct converting detectors, scintillators have shown great persistence in the field of medical imaging. In radiography, computer tomography and nuclear medicine, a variety of scintillating devices are the 'workhorses' of the clinician today. For radiography, flat X-ray detectors (FDs) with evaporated scintillation layers are at the level of product introduction. However, X-ray image intensifier tubes (XIIs) are competitive and still have features that will be hard to beat in the near future. Although XIIs have disadvantages, they have experienced a significant evolution in robust image quality and cost reduction over the decades. The so-called 'offline' detectors from film to storage phosphors seemed to have reached a plateau since the late 1970s. However, the distinction between on- and offline may soften in the future, because of new readout concepts. Detectors in computer tomography (CT) have evolved from scintillators to gaseous direct converters back to scintillators. Extreme timing requirements and detector modularity have ruled out designs that would rank as `high performance' in other fields. Modern ultra-fast ceramic scintillation detectors are a prerequisite of subsecond CT and leave breathing room for future scan times even below 0.5 s. The field of nuclear medicine is a good example of how difficult it is, to replace a cheap and reliable technology. Since many years, direct converters like CdTe and the likes are discussed to overthrow the regime of NaI:Tl in combination with photomultipliers (PMTs). Both components are well known since the 1950s and have shown remarkable staying power. Still the scintillator with the highest light output, NaI:Tl in combination with the basically noiseless PMT is almost unbeatable in low cost. In combination with modern digital electronics, drawbacks of analog circuitry like temperature drift and energy dependence can be made practically invisible to the user. New ultra-compact PMT designs could drive the design of the gamma camera towards more compactness, even without direct converting detectors.

Hell, E.; Knüpfer, W.; Mattern, D.

2000-11-01

12

Ruggedized ZnS(Ag)/epoxy alpha scintillation detector.  

National Technical Information Service (NTIS)

An alpha scintillation survey instrument has been developed which is more rugged and efficient than conventional alpha scintillation detectors that use aluminized Mylar(dagger) radiation entrance windows. This new detector consists of a mixture of ZnS(Ag)...

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

1990-01-01

13

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

14

Large Plastic Scintillation Detectors for the Nuclear Materials Identification System  

Microsoft Academic Search

Future measurements with the Nuclear Materials Identification System require large, on the order of one meter by one meter, detectors for increased sensitivity. As the container to be interrogated or the distance gets larger, increased detector size is required for increased sensitivity. Large liquid and fast plastic scintillation detectors are being designed to meet experiment requirements. Large scintillation detectors present

J. S. Neal; J. T. Mihalczo; M. T. Hiatt; J. D. Edwards

2004-01-01

15

A ruggedized ZnS(Ag)\\/epoxy alpha scintillation detector  

Microsoft Academic Search

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

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

1990-01-01

16

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

17

Liquid Scintillation Detectors for High Energy Neutrinos  

SciTech Connect

Large open volume (not segmented) liquid scintillation detectors have been generally dedicated to low energy neutrino measurements, in the MeV energy region. We describe the potential employment of large detectors (>1 kiloton) for studies of higher energy neutrino interactions, such as cosmic rays and long-baseline experiments. When considering the physics potential of new large instruments the possibility of doing useful measurements with higher energy neutrino interactions has been overlooked. Here we take into account Fermat's principle, which states that the first light to reach each PMT will follow the shortest path between that PMT and the point of origin. We describe the geometry of this process, and the resulting wavefront, which we are calling the 'Fermat surface', and discuss methods of using this surface to extract directional track information and particle identification. This capability may be demonstrated in the new long-baseline neutrino beam from Jaeri accelerator to the KamLAND detector in Japan. Other exciting applications include the use of Hanohano as a movable long-baseline detector in this same beam, and LENA in Europe for future long-baseline neutrino beams from CERN. Also, this methodology opens up the question as to whether a large liquid scintillator detector should be given consideration for use in a future long-baseline experiment from Fermilab to the DUSEL underground laboratory at Homestake.

Smith, Stefanie N.; Learned, John G. [Department of Physics and Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

2010-03-30

18

Temperature dependence of BCF plastic scintillation detectors  

NASA Astrophysics Data System (ADS)

We examined temperature dependence in plastic scintillation detectors (PSDs) made of BCF-60 or BCF-12 scintillating fiber coupled to optical fiber with cyanoacrylate. PSDs were subjected to a range of temperatures using a temperature-controlled water bath and irradiated at each temperature while either the dose was measured using a CCD camera or the spectral output was measured using a spectrometer. The spectrometer was used to examine the intensity and spectral distribution of scintillation light emitted by the PSDs, Cerenkov light generated within the PSD, and light transmitted through an isolated optical coupling. BCF-60 PSDs exhibited a 0.50% decrease and BCF-12 PSDs a 0.09% decrease in measured dose per °C increase, relative to dose measured at 22 °C. Spectrometry revealed that the total intensity of the light generated by BCF-60 and BCF-12 PSDs decreased by 0.32% and 0.13%, respectively, per °C increase. The spectral distribution of the light changed slightly with temperature for both PSDs, accounting for the disparity between the change in measured dose and total light output. The generation of Cerenkov light was temperature independent. However, light transmitted through optical coupling between the scintillator and the optical fiber also exhibited temperature dependence.

Wootton, Landon; Beddar, Sam

2013-05-01

19

Temperature dependence of BCF plastic scintillation detectors  

PubMed Central

We examined temperature dependence in plastic scintillation detectors (PSDs) made of BCF-60 or BCF-12 scintillating fiber coupled to optical fiber with cyanoacrylate. PSDs were subjected to a range of temperatures using a temperature-controlled water bath and irradiated at each temperature while either the dose was measured using a CCD camera or the spectral output was measured using a spectrometer. The spectrometer was used to examine the intensity and spectral distribution of scintillation light emitted by the PSDs, Cerenkov light generated within the PSD, and light transmitted through an isolated optical coupling. BCF-60 PSDs exhibited a 0.50% decrease and BCF-12 PSDs a 0.09% decrease in measured dose per °C increase, relative to dose measured at 22°C. Spectrometry revealed that the total intensity of the light generated by BCF-60 and BCF-12 PSDs decreased by 0.32% and 0.13%, respectively, per °C increase. The spectral distribution of the light changed slightly with temperature for both PSDs, accounting for the disparity between the change in measured dose and total light output. The generation of Cerenkov light was temperature independent. However, light transmitted through optical coupling between the scintillator and the optical fiber also exhibited temperature dependence.

Wootton, Landon; Beddar, Sam

2013-01-01

20

Utilization of Optical Filters in a Scintillation Detector  

Microsoft Academic Search

The detector described consists of a block of plastic scintillator covered by a 4? anticoincidence shield of scintillation plastic sheets. By means of optical filters, the light emitted by the shield is distinguished from the light arising from the core scintillator.

Elihu Boldt; Costa Tsipis

1961-01-01

21

A ruggedized ZnS(Ag)\\/epoxy alpha scintillation detector  

Microsoft Academic Search

An alpha scintillation survey instrument has been developed which is more rugged and efficient than conventional alpha scintillation detectors that use aluminized Mylar{dagger} 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

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

1990-01-01

22

A large area liquid scintillation multiphoton detector  

NASA Astrophysics Data System (ADS)

A 60 layer lead-liquid scintillator shower detector, which we call the SLIC, has been used for multiphoton detection in the Fermilab tagged photon spectrometer. The detector has an unimpeded active area which is 2.44 m by 4.88 m and is segmented, by means of teflon coated channels, into 3.17 cm wide strips. The 60 layers in depth are broken into three directions of alternating readouts so that three position coordinates are determined for each shower. At present the readouts are made by 334 photomultiplier tubes coupled to BBQ doped wavelength shifter bars which integrate the entire depth of the detector. It is relatively straightforward to increase the number of readouts to include longitudinal segmentation and to increase the segmentation of the outer region which are at present read out two strips to a readout. The energy and position resolutions of isolated showers are about {12%}/{?E} and 3 mm., respectively. The SLIC has been used to study the K-?+?0 decay of the D 0 [1], as well as for electron and muon identification in ? ? e +e - and ? ? ?+?- plus ?0 identification in ?p ? ?? [8].

Bharadwaj, V. K.; Cain, M. P.; Caldwell, D. O.; Denby, B. H.; Eisner, A. M.; Joshi, U. P.; Kennett, R. G.; Lu, A.; Morrison, R. J.; Pfost, D. R.; Stuber, H. R.; Summers, D. J.; Yellin, S. J.; Appel, J. A.

1985-01-01

23

Barium iodide single-crystal scintillator detectors  

SciTech Connect

We find that the high-Z crystal Barium Iodide is readily growable by the Bridgman growth technique and is less prone to crack compared to Lanthanum Halides. We have grown Barium Iodide crystals: undoped, doped with Ce{sup 3+}, and doped with Eu{sup 2+}. Radioluminescence spectra and time-resolved decay were measured. BaI{sub 2}(Eu) exhibits luminescence from both Eu{sup 2+} at 420 nm ({approx}450 ns decay), and a broad band at 550 nm ({approx}3 {micro}s decay) that we assign to a trapped exciton. The 550 nm luminescence decreases relative to the Eu{sup 2+} luminescence when the Barium Iodide is zone refined prior to crystal growth. We also describe the performance of BaI{sub 2}(Eu) crystals in experimental scintillator detectors.

Cherepy, N

2007-07-30

24

A ruggedized ZnS(Ag)/epoxy alpha scintillation detector  

SciTech Connect

An alpha scintillation survey instrument has been developed which is more rugged and efficient than conventional alpha scintillation detectors that use aluminized Mylar{dagger} 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. 2 refs., 3 figs., 2 tabs.

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

1990-01-01

25

Fundamental limits of scintillation detector timing precision.  

PubMed

In this paper we review the primary factors that affect the timing precision of a scintillation detector. Monte Carlo calculations were performed to explore the dependence of the timing precision on the number of photoelectrons, the scintillator decay and rise times, the depth of interaction uncertainty, the time dispersion of the optical photons (modeled as an exponential decay), the photodetector rise time and transit time jitter, the leading-edge trigger level, and electronic noise. The Monte Carlo code was used to estimate the practical limits on the timing precision for an energy deposition of 511 keV in 3 mm × 3 mm × 30 mm Lu2SiO5:Ce and LaBr3:Ce crystals. The calculated timing precisions are consistent with the best experimental literature values. We then calculated the timing precision for 820 cases that sampled scintillator rise times from 0 to 1.0 ns, photon dispersion times from 0 to 0.2 ns, photodetector time jitters from 0 to 0.5 ns fwhm, and A from 10 to 10?000 photoelectrons per ns decay time. Since the timing precision R was found to depend on A(-1/2) more than any other factor, we tabulated the parameter B, where R = BA(-1/2). An empirical analytical formula was found that fit the tabulated values of B with an rms deviation of 2.2% of the value of B. The theoretical lower bound of the timing precision was calculated for the example of 0.5 ns rise time, 0.1 ns photon dispersion, and 0.2 ns fwhm photodetector time jitter. The lower bound was at most 15% lower than leading-edge timing discrimination for A from 10 to 10?000 photoelectrons ns(-1). A timing precision of 8 ps fwhm should be possible for an energy deposition of 511 keV using currently available photodetectors if a theoretically possible scintillator were developed that could produce 10?000 photoelectrons ns(-1). PMID:24874216

Derenzo, Stephen E; Choong, Woon-Seng; Moses, William W

2014-07-01

26

Fundamental limits of scintillation detector timing precision  

NASA Astrophysics Data System (ADS)

In this paper we review the primary factors that affect the timing precision of a scintillation detector. Monte Carlo calculations were performed to explore the dependence of the timing precision on the number of photoelectrons, the scintillator decay and rise times, the depth of interaction uncertainty, the time dispersion of the optical photons (modeled as an exponential decay), the photodetector rise time and transit time jitter, the leading-edge trigger level, and electronic noise. The Monte Carlo code was used to estimate the practical limits on the timing precision for an energy deposition of 511 keV in 3 mm × 3 mm × 30 mm Lu2SiO5:Ce and LaBr3:Ce crystals. The calculated timing precisions are consistent with the best experimental literature values. We then calculated the timing precision for 820 cases that sampled scintillator rise times from 0 to 1.0 ns, photon dispersion times from 0 to 0.2 ns, photodetector time jitters from 0 to 0.5 ns fwhm, and A from 10 to 10?000 photoelectrons per ns decay time. Since the timing precision R was found to depend on A?1/2 more than any other factor, we tabulated the parameter B, where R = BA?1/2. An empirical analytical formula was found that fit the tabulated values of B with an rms deviation of 2.2% of the value of B. The theoretical lower bound of the timing precision was calculated for the example of 0.5 ns rise time, 0.1 ns photon dispersion, and 0.2 ns fwhm photodetector time jitter. The lower bound was at most 15% lower than leading-edge timing discrimination for A from 10 to 10?000 photoelectrons ns?1. A timing precision of 8 ps fwhm should be possible for an energy deposition of 511 keV using currently available photodetectors if a theoretically possible scintillator were developed that could produce 10?000 photoelectrons ns?1.

Derenzo, Stephen E.; Choong, Woon-Seng; Moses, William W.

2014-07-01

27

Gamma ray spectroscopy in astrophysics: Future role of scintillation detectors  

NASA Technical Reports Server (NTRS)

The future role of conventional scintillation detector telescopes for line gamma-ray astronomy is discussed. Although the energy resolution of the germanium detectors now being used by several groups is clearly desirable, the larger effective areas and higher efficiencies available with scintillation detectors is advantageous for many observations. This is particularly true for those observations of astrophysical phenomena where significant line broadening is expected.

Kurfess, J. D.

1978-01-01

28

A scintillating fission detector for neutron flux measurements  

Microsoft Academic Search

Neutron flux monitors are commonly used for a variety of nuclear physics applications. A scintillating neutron detector, consisting of a liquid scintillator loaded with fissionable material, has been developed, characterized, and tested in the beam line at the Los Alamos Neutron Science Center, and shows a significant improvement in neutron sensitivity compared with a conventional fission chamber. Recent research on

Sy Stange; Ernst I Esch; Eric A Burgett; Iain May; Ross E Muenchausen; Felicia Taw; Fredrik K Tovesson

2010-01-01

29

6Li foil scintillation sandwich thermal neutron detector  

Microsoft Academic Search

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

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

2011-01-01

30

Lightguide influence on timing response of scintillation detectors  

NASA Astrophysics Data System (ADS)

In this paper, using zero-crossing method, the neutron-gamma discrimination has been discussed to estimate the contribution of light transport on the timing characteristics of scintillation detectors. Both experimental and simulation verifications for the influence of lightguide length on the neutron-gamma discrimination quality of a 2×2 in. NE213 scintillator have been presented.

Binaei Bash, Z.; Ghal-Eh, N.; Bayat, E.; Etaati, G. R.

2013-01-01

31

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

32

Water equivalent plastic scintillation detectors in radiation therapy.  

PubMed

A review of the dosimetric characteristics and properties of plastic scintillation detectors for use in radiation therapy is presented. The detectors show many desirable qualities when exposed to megavoltage photon and electron beams, including water equivalence, energy independence, reproducibility, dose linearity, resistance to radiation damage and near temperature independence. These detectors do not require the usual conversion and/or correction factors used to convert the readings from common dosemeters to absorbed dose. Due to their small detecting volume, plastic scintillation detectors exhibit excellent spatial resolution. Detector performance, in certain specific cases, can be affected by radiation-induced light arising in the optical fibres that carry the scintillator signal to a photodetector. While this effect is negligible for photon beams, it may not be ignored for electron beams and needs to be accounted for. PMID:16882685

Beddar, A S

2006-01-01

33

A more rugged ZnS(Ag) alpha scintillation detector  

SciTech Connect

Conventional alpha scintillation detectors comprise a phosphor-coated light-pipe covered by a thin aluminized Mylar layer. This opaque radiation entrance window serves as a shield against ambient light entering the detector with minimum alpha attenuation. Unfortunately, Mylar is extremely fragile and easily punctured or torn by sticks, stones, and screws encountered during regular radiation surveys. The authors have been developing an alpha scintillation detector more rugged and durable than conventional models. This paper presents the scintillator assembly, which consists of a mixture of silver-activated zinc sulfide (ZnS(Ag)) and clear epoxy. The ZnS(Ag) scintillation powder is mixed with a low-viscosity, optically transparent epoxy and poured into a glass-smooth mold of desired shape and size.

McElhaney, S.A.; Ramsey, J.A.; Bauer, M.L.; Chiles, M.M. (Oak Ridge National Lab., TN (USA))

1990-04-01

34

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

35

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

2013-02-21

36

Retroreflector arrays for better light collection efficiency of ?-ray imaging detectors with continuous scintillation crystals without DOI misestimation  

NASA Astrophysics Data System (ADS)

A method to improve light collection efficiency of ?-ray imaging detectors by using retroreflector arrays has been tested, simulations of the behaviour of the scintillation light illuminating the retroreflector surface have been made. Measurements including retroreflector arrays in the setup have also been taken. For the measurements, positron emission tomography (PET) detectors with continuous scintillation crystals have been used. Each detector module consists of a continuous LSO-scintillator of dimensions 49x49x10 mm3 and a H8500 position-sensitive photo-multiplier (PSPMT) from Hamamatsu. By using a continuous scintillation crystal, the scintillation light distribution has not been destroyed and the energy, the centroids along the x- and y-direction and the depth of interaction (DOI) can be estimated. Simulations have also been run taking into account the use of continuous scintillation crystals. Due to the geometry of the continuous scintillation crystals in comparison with pixelated crystals, a good light collection efficiency is necessary to correctly reconstruct the impact point of the ?-ray. The aim of this study is to investigate whether micro-machine retro-reflectors improve light yield without misestimation of the impact point. The results shows an improvement on the energy and centroid resolutions without worsening the depth of interaction resolution. Therefore it can be concluded that using retroreflector arrays at the entrance side of the scintillation crystal improves light collection efficiency without worsening the impact point estimation.

Ros, A.; Lerche, Ch W.; Sebastia, A.; Sanchez, F.; Benlloch, J. M.

2014-04-01

37

Study of scintillation light from microstructure based detectors  

Microsoft Academic Search

In a previous work it has been pointed out that scintillation light, extending up to the infrared, emitted in microstructure based gaseous detectors (microstrips, microgaps, GEMs, etc.) can be used for non destructive testing of these detectors when they are associated to a CCD readout system. The choice of the gas mixture is an important issue, in so far as

M. M. Fraga; S. T. G. Fetal; F. A. F. Fragaa; E. Antunes; J. Gonqalvesb; C. C. Bueno; R. F. Marques; A. J. P. L. Policarpo

1999-01-01

38

Scintillator-fiber charged-particle track-imaging detector  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

39

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 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. Mylar is a trademark of E.I. du Pont de Nemours & Co., Inc., Wilmington, DE, USA.

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

1990-12-01

40

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

2013-01-01

41

Digital pulse shape algorithms for scintillation-based neutron detectors  

Microsoft Academic Search

We discuss the application of digital pulse shape algorithms to n\\/? pulse shape discrimination (PSD) in a boron-enriched liquid scintillator, where the use of digital techniques has potential applications for neutron monitors. High-speed flash analogue-to-digital converters (ADCs) have opened up new possibilities for scintillator detector systems based upon digital event-by-event data acquisition. Using an 8-bit 1 GS\\/s waveform digitiser, we

S. D. Jastaniah; P. J. Sellin

2001-01-01

42

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

43

Light collection in scintillation detector composites for neutron detection  

Microsoft Academic Search

With the goal of developing neutron detectors of high detection efficiency and fast response, the authors have been investigating the heterogeneous combination of neutron-conversion materials in a plastic or liquid scintillation matrix. One such combination consists of thin-wall glass microspheres filled with high pressure ³He gas dispersed in plastic scintillator. The authors have now developed glass formulations that are capable

G. F. Knoll; T. F. Knoll; T. M. Henderson

1988-01-01

44

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

2011-02-01

45

Performance of photomultiplier tubes and sodium iodide scintillation detector systems  

Microsoft Academic Search

The performance of photomultiplier tubes (PMT's) and scintillation detector systems incorporating 50.8 by 1.27 cm NaI (T l) crystals was investigated to determine the characteristics of the photomultiplier tubes and optimize the detector geometry for the Burst and Transient Source Experiment on the Gamma Ray Observatory. Background information on performance characteristics of PMT's and NaI (T l) detectors is provided,

C. A. Meegan

1981-01-01

46

Smaller, Lower-Power Fast-Neutron Scintillation Detectors  

NASA Technical Reports Server (NTRS)

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

Patel, Jagdish; Blaes, Brent

2008-01-01

47

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

48

Scintillator-fiber charged particle track-imaging detector  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

49

Miniature scintillating detector for small field radiation therapy.  

PubMed

In planning stereotactic radiosurgery treatments, depth dose curves, profiles, and dose rate of treatment beams are difficult to obtain with conventional detectors because of loss of lateral electronic equilibrium and volume averaging. A scintillating detector with high spatial resolution and good reliability has been developed to overcome this problem. The miniature dosimeter consists of two identical radiation-resistant 10 m long silica optical fibers, each connected to an independent silicon photodiode. A small cylindrical polystyrene scintillator (3.9 mm3) is optically glued to the detection fiber. The light seen by the photodiode connected to this fiber arises from fluorescence of the scintillator and from the Cerenkov effect produced in silica. The reference signal produced by the fiber without scintillator is used to subtract the Cerenkov light contribution from the raw detector response. The sensitive volume of the scintillating detector is nearly water-equivalent and thus minimizes dose distribution perturbation in water. The miniature dosimeter has a spatial resolution comparable to the film-densitometer system. Profiles of 1 cm diam, 6 MV photon beam measured with both systems show very similar shapes. Furthermore, the use of photodiodes instead of photomultiplier tubes gives a better stability response and offers the possibility to perform absolute dosimetry. PMID:10619239

Létourneau, D; Pouliot, J; Roy, R

1999-12-01

50

Nonproportionality of Scintillator Detectors: Theory and Experiment  

Microsoft Academic Search

On the basis of nonproportionality data obtained for several scintillators, we have developed a model to describe the carrier dynamics to fit the light yield versus electron energy. The theory of Onsager was adapted to explain how the carriers form excitons or sequentially arrive at the activators to promote the ion to an excited state, and the theory of Birks

Stephen A. Payne; Nerine J. Cherepy; Giulia Hull; John D. Valentine; William W. Moses; Woon-Seng Choong

2009-01-01

51

A scintillating optical fiber track imaging detector  

Microsoft Academic Search

In this paper we describe a prototype of the scintillating optical fiber isotope experiment (SOFIE) and give results of a Bevalac calibration using iron nuclei to study the measurement precision in range and trajectory which can be obtained. We have measured the range of iron nuclei with approximate energy 500 MeV\\/amu entering the SOFIE instrument to a precision of 200-300

W. R. Binns; J. J. Connell; P. F. Dowkontt; J. W. Epstein; M. H. Israel; J. Klarmann

1986-01-01

52

Current trends in scintillator detectors and materials  

Microsoft Academic Search

The last decade has seen a renaissance in inorganic scintillator development for gamma ray detection. Lead tungstate (PbWO4) has been developed for high-energy physics experiments, and possesses exceptionally high density and radiation hardness, albeit with low luminous efficiency. Lutetium orthosilicate or LSO (Lu2SiO5:Ce) possesses a unique combination of high luminous efficiency, high density, and reasonably short decay time, and is

William W. Moses

2002-01-01

53

Warhead counting using neutron scintillators: detector development, testing, and demonstration  

Microsoft Academic Search

The authors describe the development of a fast-neutron detector based on a boron-loaded plastic scintillator used previously for space applications. The detector rejects gammas and scattered low-energy neutrons, and its segmentation allows narrow fan-shaped collimation within ±20° horizontally and ±50° vertically. Testing included distinguishing between mockups with either two or three warheads and locating the ten warheads on a silo-based

R. C. Byrd; G. F. Auchampaugh; C. E. Moss; W. C. Feldman

1992-01-01

54

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

55

a Scintillator Based Muon Detector for the Linear Collider  

NASA Astrophysics Data System (ADS)

The requirements for a linear collider muon detector are discussed and a solution is presented based on solid scintillating strips with embedded wavelength shifting optical fibers. Multi-anode photo-multiplier tubes are a good candidate for photon detection. Their single photo-electron response can be calibrated using fast pulses from light-emitting diodes.

Karchin, Paul E.

56

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

57

Characterization of a scintillating fibers read by MPPC detectors trigger prototype for the AMADEUS experiment  

NASA Astrophysics Data System (ADS)

Multi-Pixel Photon Counters (MPPC) consist of hundreds of micro silicon Avalanche PhotoDiodes (APD) working in Geiger mode. The high gain and the low noise, typical of these devices, together with their good performance in magnetic field, make them ideal readout detectors for scintillating fibers as trigger detectors in particle and nuclear physics experiments like AMADEUS, where such detectors are planned to be used to trigger on charged kaon pairs. In order to investigate the detection efficiency of such a system, a prototype setup consisting of 32, 1 mm diameter scintillating fibers, arranged in two double layers of 16 fibers each, and read out at both sides by 64 MPPCs with an ad-hoc built readout electronics, was tested at the ?M-1 line of the Paul Scherrer Institute (PSI) in Villigen, Switzerland. The detection efficiency and the trigger capability were measured on a beam containing protons, electrons, muons and pions with a momentum of 440 MeV/c. The measured average efficiency for protons for a double layer of scintillating fibers (96.2±1.0%) represents a guarantee of the good performance of this system as a trigger for the AMADEUS experiment.

Bazzi, M.; Berucci, C.; Curceanu, C.; D'Uffizi, A.; Piscicchia, K.; Poli Lener, M.; Romero Vidal, A.; Sbardella, E.; Scordo, A.; Vazquez Doce, O.

2013-05-01

58

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.

59

Monte Carlo based calibration of scintillation detectors for laboratory and in situ gamma ray measurements.  

PubMed

The calibration of scintillation detectors for gamma radiation in a well characterized setup can be transferred to other geometries using Monte Carlo simulations to account for the differences between the calibration and the other geometry. In this study a calibration facility was used that is constructed from bricks of well-known activity concentrations of ??K and of radionuclides from the ²³?U- and ²³²Th-series. Transfer of the calibration was attempted to a Marinelli beaker geometry with the detector inside a lead shield and to an in situ application with the detector positioned on a sand bed. In general this resulted in good correspondence (within 5-10%) between the activity concentrations derived using the transferred calibration and activities that were derived by independent measurements. Some discrepancies were identified that were attributed to coincident summing in the natural decay series and interference of radon. PMID:21251733

van der Graaf, E R; Limburg, J; Koomans, R L; Tijs, M

2011-03-01

60

Setup to investigate rare processes with neutron producing.  

National Technical Information Service (NTIS)

An experimental setup has been created to study rare processes with neutron production. The detecting system comprises a scintillation detector in the form of a cup around which thermal neutron detectors (BF3 counters) set in paraffin are placed parallel ...

V. M. Bystritskij N. I. Zhuravlev S. I. Merzlyakov V. T. Sidorov V. A. Stolupin

1995-01-01

61

Modelling of scintillator based flat-panel detectors with Monte-Carlo simulations  

NASA Astrophysics Data System (ADS)

Scintillator based flat panel detectors are state of the art in the field of industrial X-ray imaging applications. Choosing the proper system and setup parameters for the vast range of different applications can be a time consuming task, especially when developing new detector systems. Since the system behaviour cannot always be foreseen easily, Monte-Carlo (MC) simulations are keys to gain further knowledge of system components and their behaviour for different imaging conditions. In this work we used two Monte-Carlo based models to examine an indirect converting flat panel detector, specifically the Hamamatsu C9312SK. We focused on the signal generation in the scintillation layer and its influence on the spatial resolution of the whole system. The models differ significantly in their level of complexity. The first model gives a global description of the detector based on different parameters characterizing the spatial resolution. With relatively small effort a simulation model can be developed which equates the real detector regarding signal transfer. The second model allows a more detailed insight of the system. It is based on the well established cascade theory, i.e. describing the detector as a cascade of elemental gain and scattering stages, which represent the built in components and their signal transfer behaviour. In comparison to the first model the influence of single components especially the important light spread behaviour in the scintillator can be analysed in a more differentiated way. Although the implementation of the second model is more time consuming both models have in common that a relatively small amount of system manufacturer parameters are needed. The results of both models were in good agreement with the measured parameters of the real system.

Reims, N.; Sukowski, F.; Uhlmann, N.

2011-01-01

62

Research in high energy physics: Scintillating fiber detector development for the SSC: Annual progress report  

SciTech Connect

The scintillating fiber detector development program at the University of Notre Dame is divided into several components. These include: Research on scintillating glass fiber materials; Research on scintillating plastic fiber materials; Research on scintillating liquids in fiber capillaries; Studies of improvements in image intensification and light amplification of appropriate test and development facilities at Notre Dame. The overall goal of the program is to develop efficient scintillating fiber detectors with long, optical attenuation length, and excellent radiation resistance properties for tracking and microvertex detectors and as component active sampling materials for scintillation calorimetry. We now discuss each of these programs in turn. 2 figs., 3 tabs.

Ruchti, R.C.

1988-07-14

63

Photoelectron anticorrelations and sub-Poisson statistics in scintillation detectors.  

PubMed

The performance of scintillation detectors for x rays and gamma rays is limited fundamentally by the statistics of the scintillation light and the resulting photoelectrons. This paper presents a new experimental approach to studying these statistics by observing correlations in the signals from two photodetectors. It is shown that the Fano factors (ratios of variance to mean), both for the number the photoelectrons produced on the photocathode of the photomultiplier and for the underlying number of scintillation photons, can be deduced from these correlations. For LaBr(3)(Ce) and 662 keV gamma rays, the photopeak signals obtained by photomultipliers on opposite faces of a thin sample are negatively correlated, and the Fano factor for the photoelectrons is significantly less than one. The inferred Fano factor for the optical photons is very small, indistinguishable from zero within experimental error. PMID:20725609

Bousselham, Abdelkader; Barrett, Harrison H; Bora, Vaibhav; Shah, Kanai

2010-08-01

64

Characterizing the response of miniature scintillation detectors when irradiated with proton beams  

Microsoft Academic Search

Designing a plastic scintillation detector for proton radiation therapy requires careful consideration. Most of the plastic scintillators should not perturb a proton beam if they are sufficiently small but may exhibit some energy dependence due to the quenching effect. In this work, we studied the factors that would affect the performance of such scintillation detectors. We performed Monte Carlo simulations

Louis Archambault; Jerimy C Polf; Luc Beaulieu; Sam Beddar

2008-01-01

65

Physics with the large liquid-scintillator detector LENA  

Microsoft Academic Search

A large liquid-scintillator detector with 50 kt target mass in an underground location of at least 4000 m.w.e. is considered as a unique tool for low-energy neutrino detection and the search for rare events from astrophysical sources and up to now unobserved processes beyond the Standard Model. In this contribution, the physics potential of LENA for selected topics is discussed.

T. Lachenmaier; F. von Feilitzsch; M. Göger-Neff; T. Lewke; T. Marrodán Undagoitia; Q. Meindl; R. Möllenberg; L. Oberauer; J. Peltoniemi; W. Potzel; M. Tippmann; J. Winter; M. Wurm

2010-01-01

66

Two-dimensional neutron scintillation detector with optimal gamma discrimination  

SciTech Connect

The gamma sensitivity of a two-dimensional scintillation neutron detector based on position sensitive photomultipliers (Hamamatsu R2387 PM) has been minimized by a digital differential discrimination unit. Since the photomultiplier gain is position-dependent by [+-]25% a discrimination unit was developed where digital upper and lower discrimination levels are set due to the position-dependent photomultiplier gain obtained from calibration measurements. By this method narrow discriminator windows can be used to reduce the gamma background drastically without effecting the neutron sensitivity of the detector. The new discrimination method and its performance tested by neutron measurements will be described. Experimental results concerning spatial resolution and [gamma]-sensitivity are presented.

Kanyo, M.; Reinartz, R.; Schelten, J.; Mueller, K.D. (Research Center Juelich GmbH (Germany). Central Lab. for Electronics)

1993-08-01

67

Optical scattering lengths in large liquid-scintillator neutrino detectors.  

PubMed

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. PMID:20515130

Wurm, M; von Feilitzsch, F; Göger-Neff, M; Hofmann, M; Lachenmaier, T; Lewke, T; Marrodán Undagoitia, T; Meindl, Q; Möllenberg, R; Oberauer, L; Potzel, W; Tippmann, M; Todor, S; Traunsteiner, C; Winter, J

2010-05-01

68

Optical scattering lengths in large liquid-scintillator neutrino detectors  

NASA Astrophysics Data System (ADS)

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.; von Feilitzsch, F.; Göger-Neff, M.; Hofmann, M.; Lachenmaier, T.; Lewke, T.; Undagoitia, T. Marrodán; Meindl, Q.; Möllenberg, R.; Oberauer, L.; Potzel, W.; Tippmann, M.; Todor, S.; Traunsteiner, C.; Winter, J.

2010-05-01

69

Analytical formulae for borehole scintillation detectors efficiency calibration  

NASA Astrophysics Data System (ADS)

The borehole scintillation detectors (with central borehole) are useful for the identification and quantification of unknown gamma-ray emitting radionuclides in geological and environmental samples due to the near 4 ? solid angle that can be obtained with them. In addition, the 4 ? gamma-ray-counting is a well-established method for direct activity measurements, and is especially suited for radionuclides with complex gamma-ray spectra. A straightforward theoretical approach was carried out to calculate the efficiencies (total, ?T and geometrical, ?g) of borehole scintillation detectors. The approach depends on the accurate calculation of two important factors: the path length, d, the photon traverses within the active volume of a gamma detector, and the geometrical solid angle, ?, subtended by the source to the detector at the point of entrance. These two factors are theoretically derived through straightforward analytical formulae. Furthermore, the attenuation of photons by the source container and the detector housing materials is also treated by calculating the photon path length through these materials. The comparisons with the experimental and Monte Carlo method works reported in the literature indicate that the present approach is useful in the efficiency calibration of such complicated gamma-ray spectrometer.

Abbas, Mahmoud I.

2010-10-01

70

Effects of detector-source distance and detector bias voltage variations on time resolution of general purpose plastic scintillation detectors.  

PubMed

Effects of source-detector distance and the detector bias voltage variations on time resolution of a general purpose plastic scintillation detector such as BC400 were investigated. (133)Ba and (207)Bi calibration sources with and without collimator were used in the present work. Optimum source-detector distance and bias voltage values were determined for the best time resolution by using leading edge timing method. Effect of the collimator usage on time resolution was also investigated. PMID:23041387

Ermis, E E; Celiktas, C

2012-12-01

71

Development and characterization of scintillating fiber—APD-based detector  

NASA Astrophysics Data System (ADS)

We report about a detector based on the use of scintillating fibers readout by Avalanche Photodiodes (APDs). The APDs are suitable for use in harsh environments, like high magnetic fields and helium atmosphere. In addition they can be employed where a compact device is needed. We investigated several issues related to such a detector: moulding of fibers with customized shapes, optimization of the light transport along the fiber and the right coupling to the readout device. Here we report on our tests about fiber bending and several measurements on various coatings to achieve the best results. Finally, we discuss the final performance of our detector employed in the MEG experiment, assembled and ready to use.

De Gerone, M.; Dussoni, S.; Gatti, F.; Rossella, M.; Valle, R.

2009-10-01

72

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

73

Reconstruction of supernova ??, ??, ?¯?, and ?¯? neutrino spectra at scintillator detectors  

NASA Astrophysics Data System (ADS)

We present a new technique to directly reconstruct the spectra of ??, ??, ?¯?, and ?¯? from a supernova, using neutrino-proton elastic scattering events (?+p??+p) at scintillator detectors. These neutrinos, unlike ?e and ?¯e, have only neutral current interactions, which makes it very challenging, with any reaction, to detect them and measure their energies. With updated inputs from theory and experiments, we show that this channel provides a robust and sensitive measure of their spectra. Given the low yields and lack of spectral information in other neutral current channels, this is perhaps the only realistic way to extract such information. This will be indispensable for understanding flavor oscillations of SN neutrinos, as it is likely to be impossible to disentangle neutrino mixing from astrophysical uncertainties in a SN without adequate spectral coverage of all flavors. We emphasize that scintillator detectors, e.g., Borexino, KamLAND, and SNO+, have the capability to observe these events, but they must be adequately prepared with a trigger for a burst of low-energy events. We also highlight the capabilities of a larger detector like LENA.

Dasgupta, Basudeb; Beacom, John F.

2011-06-01

74

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

75

Warhead counting using neutron scintillators: Detector development, testing, and demonstration  

NASA Astrophysics Data System (ADS)

Although the number of warheads on a missile can be determined relatively simply by a scan of the emitted gamma radiation, this approach may be considered too intrusive because of the possibility of revealing high resolution energy or position information. Neutron spectra are nearly featureless, and obtaining the position resolution needed to reveal warhead details would be very difficult. We describe the development of a fast neutron detector based on a boron-loaded plastic scintillator used previously for space applications. The detector rejects gammas and scattered low energy neutrons, and its segmentation allows narrow fan-shaped collimation within + or - 20 degs horizontally and + or - 50 degs vertically. Testing includes distinguishing between mockups with either two or three warheads and locating the ten warheads on a silo-based Peacekeeper missile.

Byrd, R. C.; Auchampaugh, G. F.; Moss, C. E.; Feldman, W. C.

1991-11-01

76

A setup for soft proton irradiation of X-ray detectors for future astronomical space missions  

NASA Astrophysics Data System (ADS)

Protons that are trapped in the Earth's magnetic field are one of the main threats to astronomical X-ray observatories. Soft protons, in the range from tens of keV up to a few MeV, impinging on silicon X-ray detectors can lead to a significant degradation of the detector performance. Especially in low earth orbits an enhancement of the soft proton flux has been found. A setup to irradiate detectors with soft protons has been constructed at the Van-de-Graaff accelerator of the Physikalisches Institut of the University of Tübingen. Key advantages are a high flux uniformity over a large area, to enable irradiations of large detectors, and a monitoring system for the applied fluence, the beam uniformity, and the spectrum, that allows testing of detector prototypes in early development phases, when readout electronics are not yet available. Two irradiation campaigns have been performed so far with this setup. The irradiated detectors are silicon drift detectors, designated for the use on-board the LOFT space mission. This paper gives a description of the experimental setup and the associated monitoring system.

Diebold, Sebastian; Azzarello, Philipp; Del Monte, Ettore; Feroci, Marco; Jochum, Josef; Kendziorra, Eckhard; Perinati, Emanuele; Rachevski, Alexandre; Santangelo, Andrea; Tenzer, Christoph; Vacchi, Andrea; Zampa, Gianluigi; Zampa, Nicola

2013-09-01

77

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

2013-03-01

78

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

79

Silicon photo-multiplier readouts for scintillator-based gamma-ray detectors in space  

Microsoft Academic Search

New scintillator materials have been shown to hold great potential for low-cost, reliable gamma-ray detectors in high-energy astronomy and solar physics. Commercially available silicon photo-multipliers (SiPMs) promise to make scintillator-based instruments even more attractive by reducing mass and power requirements. SiPMs have by now been shown to perform well as readouts for scintillator gamma-ray detectors in the laboratory. We present

Peter F. Bloser; Jason S. Legere; Luke F. Jablonski; Christopher M. Bancroft; Mark L. McConnell; James M. Ryan

2010-01-01

80

X-ray detector based on a bulk micromachined photodiode combined with a scintillating crystal  

Microsoft Academic Search

In this paper we report on the design, fabrication, assembly and testing of an x-ray detector based on a bulk micromachined photodiode (BMMPD) with a cavity filled with a scintillating crystal. The x-ray photons that reach the detector are first converted to visible light by the scintillating crystal. The visible light is then detected by the BMMPD, producing an electric

J. G. Rocha; C. G. J. Schabmueller; N. F. Ramos; S. Lanceros-Mendez; M. F. Costa; A. G. R. Evans; R. F. Wolffenbuttel; J. H. Correia

2003-01-01

81

The empirical characterization of organic liquid scintillation detectors by the normalized average of digitized pulse shapes  

Microsoft Academic Search

The application of the digital acquisition of pulses from a liquid scintillator to detector characterization is described. Experimental data for a mixed neutron\\/gamma-ray field have been recorded digitally. An empirical method for the characterization of liquid scintillation detectors, in terms of their pulse shape, has been developed which is quick and easy. It provides generic pulses shapes for use in

M. D. Aspinall; B. D'Mellow; R. O. Mackin; M. J. Joyce; Z. Jarrah; A. J. Peyton

2007-01-01

82

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

83

Design of a high resolution positron emission tomograph using solid state scintillation detectors  

Microsoft Academic Search

The authors propose a new concept of positron camera achieving nearly isotropic spatial resolution and uniform sensitivity throughout the useful field-of-view. The design is based on a quad scintillator dual channel detector module using two avalanche photodiodes as photodetectors. Original features include bilayered scintillators to measure the depth of interaction, tilted detectors relative to the radial direction to insure proper

C. Carrier; C. Martel; D. Schmitt; R. Lecomte

1988-01-01

84

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

85

(Effects of ionizing radiation on scintillators and other particle detectors)  

SciTech Connect

It is my task to summarise the great variety of topics (covering a refreshing mix of physics, chemistry and technology) presented at this conference, which has focused on the effects of ionising radiation on scintillators and other particle detectors. One of the reasons and the central interest of many of the participants was the use of such detectors in experiments at two future large hadron colliders: the Superconducting Super Collider to be operating outside of Dallas in the United States by the turn of the decade and its European counterpart the Large Hadron Collider to be operating outside of Geneva in Switzerland on a similar time scale. These accelerators are the apple of the high energy physicist's eye.'' Their goal is to uncover the elusive Higgs particle and thereby set the cornerstone in our current knowledge of elementary particle interactions. This is the Quest, and from this lofty height the presentations rapidly moved on to the specific questions of experimental science: how such an experiment is carried out; why radiation damage is an issue; how radiation damage affects detectors; which factors affect radiation damage characteristics; which factors are not affected by radiation damage; and how better detectors may be constructed. These were the substance of this conference.

Proudfoot, J.

1992-01-01

86

Setup for irradiation and characterization of materials and Si particle detectors at cryogenic temperatures  

NASA Astrophysics Data System (ADS)

A novel facility for proton irradiation with sample cryocooling has been developed at the Accelerator Laboratory of Helsinki University (equipped with a 5 MV tandem accelerator). The setup enables unique experiments to be carried out within the temperature range of 10-300 K. The setup has been constructed for "on-line" studies of vacancies with positron annihilation spectroscopy (PAS) including the option for optical ionization of the vacancies, and for current-voltage ( IV) measurements of irradiated silicon particle detectors. The setup is described in detail and typical performance characteristics are provided. The facility functionality was tested by performing PAS experiments with high-resistivity silicon and by IV measurements for two types of irradiated silicon particle detectors.

Väyrynen, S.; Pusa, P.; Sane, P.; Tikkanen, P.; Räisänen, J.; Kuitunen, K.; Tuomisto, F.; Härkönen, J.; Kassamakov, I.; Tuominen, E.; Tuovinen, E.

2007-03-01

87

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

88

Measuring directionality in double-beta decay and neutrino interactions with kiloton-scale scintillation detectors  

NASA Astrophysics Data System (ADS)

Large liquid-scintillator-based detectors have proven to be exceptionally effective for low energy neutrino measurements due to their good energy resolution and scalability to large volumes. The addition of directional information using Cherenkov light and fast timing would enhance the scientific reach of these detectors, especially for searches for neutrino-less double-beta decay. In this paper, we propose a technique for extracting particle direction using the difference in arrival times for Cherenkov and scintillation light, and evaluate several detector advances in timing, photodetector spectral response, and scintillator emission spectra that could be used to make direction reconstruction a reality in a kiloton-scale detector.

Aberle, C.; Elagin, A.; Frisch, H. J.; Wetstein, M.; Winslow, L.

2014-06-01

89

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

90

Characteristics of scintillation detectors based on inorganic scintillators and SiPM light readout  

NASA Astrophysics Data System (ADS)

Recently, a silicon photomultiplier (SiPM) became one of the strongest candidates for application in PET-MR or SPECT-MR dual-modality scanners. However, optimization of the scintillation detectors with SiPM light readout requires different approach than in the case of classic photomultipliers. The finite number of micro-cells in a SiPM creates nonlinear response for high number of incident photons. Moreover, the size and total number of micro-cells defines fill factor, which in turn affects the photon detection efficiency (PDE). Response of SiPMs is also highly sensitive to bias voltage causing changes in PDE and excess noise factor (ENF). Finally, each cell posses an effective dead time needed to fully recharge that cell after the photon detection. In this work the listed above unique features of SiPMs are overviewed. The reported data also contain measurements of energy resolution and 22Na time resolution.

Szcze&?acute; niak, T.; Grodzicka, M.; Moszy?ski, M.; Szaw?owski, M.; Wolski, D.; Baszak, J.

2013-02-01

91

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

PubMed

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

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

2014-01-01

92

Influence of Depth of Interaction upon the Performance of Scintillator Detectors  

PubMed Central

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

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

2014-01-01

93

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

2012-04-01

94

A Scintillation Detector for the Measurement of Thermal Neutrons in Subcritical Assembly  

Microsoft Academic Search

With the view toward measuring neutron flux in a subcritical assembly, a detector consisting of a ?-ray insensitive scintillator based on LiF, ZnS(Ag) and polyethylene combined with a long light guide has been developed. A description is given of performance obtained with this detector, in comparison with BF3 counters and glass scintillator. It has proved that the newly deviced detector

Takao T?J?; Takeo NIWA; Tadashi NAKAJIMA; Makoto KOND?

1967-01-01

95

Disentangling the air shower components using scintillator and water Cherenkov detectors  

NASA Astrophysics Data System (ADS)

We consider a ground array of scintillation and water Cherenkov detectors with the purpose of determining the muon content of air showers. The different response characteristics of these two types of detectors to the components of the air shower provide a way to infer their relative contributions. We use a detailed simulation to estimate the impact of parameters, such as scintillation detector size, in the determination of the size of the muon component.

Gonzalez, Javier G.; Roth, Markus; Engel, Ralph

2013-06-01

96

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

PubMed Central

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

Bircher, Chad; Shao, Yiping

2012-01-01

97

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

98

Setup to investigate rare neutron producing processes  

Microsoft Academic Search

An experimental setup has been created to study rare processes with neutron production. The detecting system comprises a scintillation detector in the form of a cup around which thermal neutron detectors (BF3 counters) set in paraffin are placed parallel to the common axis in two concentric circles. The detecting system and registering electronics make it possible to obtain time and

V. M Bystritsky; N. I. Zhuravlev; S. I. Merzlyakov; V. T Sidorov; V. A Stolupin; A. V. Strelkov; V. N Shvetsov

1996-01-01

99

A new compact position-sensitive PMT for scintillation detectors  

SciTech Connect

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 and 6(X) + 6(Y) crossed plate anodes in a 25.7 mm square x 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 radiation imaging systems. In comparison with the former type of PS-PMT (Hamamatsu R5900-C8), the new PS-PMT provides smaller light spread and better position response. Also, by removing the flange at the bottom of the PS-PMT, the ratio of the effective area to the outward area is increased. The spatial resolution capability was demonstrated by imaging a stratified LSO array having an element of 1.8 mm x 1.8 mm x 10 mm. Each crystal element is clearly identified on the image map with 662 keV uniform gamma-ray irradiation. This paper describes the characteristics of the new PS-PMT and the experimental results for a gamma-ray imaging detector.

Nagai, S.; Shimoi, H.; Yoshizawa, Y [Hamamatsu Photonics K.K., Toyooka (Japan). Electron Tube Center] [Hamamatsu Photonics K.K., Toyooka (Japan). Electron Tube Center; Watanabe, M. [Hamamatsu Photonics K.K., Hirakuchi (Japan). Central Research Lab.] [Hamamatsu Photonics K.K., Hirakuchi (Japan). Central Research Lab.; Liu, H. [Zhejiang Univ. (China). State Key Lab. of Modern Optical Instrumentation] [Zhejiang Univ. (China). State Key Lab. of Modern Optical Instrumentation

1999-06-01

100

Two dimensional and linear scintillation detectors for fast neutron imaging — comparative analysis  

NASA Astrophysics Data System (ADS)

The paper was aimed to compare performance capabilities of two types of scintillation detectors commonly used for fast neutron imaging: two dimensional and linear ones. Best-case values of quantum efficiency, spatial resolution and capacity were estimated for detectors with plastic converter-screen in case of 14 MeV neutrons. For that there were examined nuclear reactions produced in converter-screen by fast neutrons, spatial distributions of energy release of emerged charged particles and amplitude distributions of scintillations generated by these particles. The paper shows that the efficiency of the linear detector is essentially higher and this detector provides potentially better spatial resolution in comparison with the two dimensional detector. But, the two dimensional detector surpasses the linear one in capacity. The presented results can be used for designing radiographic fast neutron detectors with organic scintillators.

Mikerov, V. I.; Koshelev, A. P.; Ozerov, O. V.; Sviridov, A. S.; Yurkov, D. I.

2014-05-01

101

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

SciTech Connect

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. III; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623-1299 (United States); Caggiano, J. A.; Carman, M. L.; Clancy, T. J.; Hatarik, R.; McNaney, J.; Zaitseva, N. P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2012-10-15

102

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

103

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

104

The timing resolution of scintillation-detector systems: Monte Carlo analysis  

Microsoft Academic Search

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

Woon-Seng Choong

2009-01-01

105

Performance of digital algorithms for n\\/? pulse shape discrimination using a liquid scintillation detector  

Microsoft Academic Search

We have investigated the use of digital data acquisition techniques to analyze the performance of pulse shape discrimination from a liquid scintillation detector in mixed neutron\\/gamma radiation fields. Three digital pulse shape discrimination methods were explored, applied to pulses digitized from a liquid scintillator using a high-speed waveform digitizer. The various features of these digital discrimination techniques are discussed and

P. J. Sellin; G. Jaffar; S. D. Jastaniah

2003-01-01

106

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

107

A positron camera detector design with cross-coupled scintillators and quadrant sharing photomultipliers  

Microsoft Academic Search

A new positron camera scintillation detector design is proposed. This design uses discrete scintillators which are tightly optically coupled (glued) together to form a block. The coupling interfaces between crystals have different degrees of polish depending on the interface location within the block. Each block has the same dimension as that of the photomultipliers (PMTs) used, but the blocks and

Wai-Hoi Wong

1993-01-01

108

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

109

Detection of Extensive Cosmic Air Showers by Small Scintillation Detectors with Wavelength-Shifting Fibres  

ERIC Educational Resources Information Center

A set of three small scintillation detectors was employed to measure correlated events due to the passage of cosmic muons originating from extensive air showers. The coincidence rate between (any) two detectors was extracted as a function of their relative distance. The difference between the arrival times in three non-aligned detectors was used…

Aiola, Salvatore; La Rocca, Paola; Riggi, Francesco; Riggi, Simone

2012-01-01

110

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

Microsoft Academic Search

An X-ray imaging detector has been developed for dental applications. The principle of this detector is based on application of a silicon charge coupled device covered by a scintillating wave-guide screen. Previous studies of such a detector showed promising results concerning the spatial resolution but low performance in terms of signal to noise ratio (SNR) and sensitivity. Recent results confirm

X. Badel; A. Galeckas; J. Linnros; P. Kleimann; C. Fröjdh; C. S Petersson

2002-01-01

111

Monte Carlo simulation of the standardization of 22Na using scintillation detector arrays.  

PubMed

In order to calibrate PET devices by a sealed point source, we contrived an absolute activity measurement method for the sealed point source using scintillation detector arrays. This new method was verified by EGS5 Monte Carlo simulation. PMID:20083411

Sato, Y; Murayama, H; Yamada, T; Hasegawa, T; Oda, K; Unno, Y; Yunoki, A

2010-01-01

112

Proton-induced radioactivity in NaI (Tl) scintillation detectors  

NASA Technical Reports Server (NTRS)

Radioactivity induced by protons in sodium iodide scintillation crystals were calculated and directly measured. These data are useful in determining trapped radiation and cosmic-ray induced, background-counting rates in spaceborne detectors.

Fishman, G. J.

1977-01-01

113

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

NASA Technical Reports Server (NTRS)

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

Link, Jason

2011-01-01

114

The empirical characterization of organic liquid scintillation detectors by the normalized average of digitized pulse shapes  

Microsoft Academic Search

The application of the digital acquisition of pulses from a liquid scintillator to detector characterization is described. Experimental data for a mixed neutron\\/?-ray field have been recorded digitally.An empirical method for the characterization of liquid scintillation detectors, in terms of their pulse shape, has been developed which is quick and easy. It provides generic pulses shapes for use in pulse-shape

M. D. Aspinall; B. D’Mellow; R. O. Mackin; M. J. Joyce; Z. Jarrah; A. J. Peyton

2007-01-01

115

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

Microsoft Academic Search

Digital X-ray imaging detectors designed for soft X-rays (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

Michael J. Flynn; Sean M. Hames; Scott J. Wilderman; James J. Ciarelli

1995-01-01

116

NAIAD: an advanced sodium iodide scintillation detector with improved sensitivity to WIMP dark matter  

Microsoft Academic Search

A novel bulk NaI detector, NAIAD, developed by the UK Dark Matter Collaboration (UKDMC), combines improved light collection from suspending an unencapsulated crystal viewed by photomultipliers (PMTs) in mineral oil with background reduction from a liquid scintillator Compton veto. Low background NaI(Tl) detectors, which use pulse shape analysis (PSA) to distinguish scintillation from background electron recoils from nuclear recoils, currently

C. D. Peak; J. E. McMillan; N. J. C. Spooner; J. W. Roberts

1998-01-01

117

Beam tests of a 3-D position sensitive scintillation detector  

SciTech Connect

An array of 30 position sensitive scintillator bars has been tested in a gamma-ray beam from I.N.S.T.N. Van de Graff facility at the Centre d'Etudes Nucleaires, Saclay, France. The gamma-ray energies ranged from 6 MeV to 17 MeV. The bars are similar to those proposed for use in the GRASP gamma-ray telescope satellite imaging plane. They are manufactured from CsI(T1) covered with a highly reflective diffusive wrapping, and are read out using large area PIN photodiodes. Each bar measures 15.0 cm by 1.3 cm by 1.3 cm. The beam test unit was comprised of 30 bars stacked in a 5 by 6 array. The photodiodes were optically coupled to the end face of each bar and were connected to a processing chain comprised of a low noise preamplifier, a high gain shaping amplifier, and a digitisation and data collection system. Several experiments were performed with the unit to assess the spectral response, position resolution, and background rejection capabilities of the complete detector. The test procedure is explained and some results are presented.

Labanti, C.; Hall, C.J.; Agrinier, B.; Byard, K.; Dean, A.J.; Goldwurm, A.; Harding, J.S.

1989-02-01

118

Characterization of a cubic EJ-309 liquid scintillator detector  

NASA Astrophysics Data System (ADS)

A cubic EJ-309 liquid scintillator of 10 cm width has been characterized for its response to ?-rays and neutrons. Response functions to ?-rays were measured with calibrated radionuclide ?-ray sources in the energy range from 400 keV to 6 MeV. Response functions for neutrons were obtained from measurements at the PTB Van de Graaff accelerator with quasi-monoenergetic neutron beams in the energy range from 500 keV to 2.7 MeV, and at the PTB cyclotron with time-of-flight (TOF) measurements in the energy range from 2.5 to 14 MeV. The light output and resolution functions for electrons and protons were derived by a least squares adjustment to experimental data using theoretical response functions determined with Monte Carlo simulations. The simulated response function for neutron was validated by results of measurements with an AmBe neutron source which was characterized for its total neutron intensity. The results indicate that the cubic EJ-309 detector is suitable for use in mixed ?-ray and neutron fields.

Tomanin, A.; Paepen, J.; Schillebeeckx, P.; Wynants, R.; Nolte, R.; Lavietes, A.

2014-08-01

119

Lithium glass scintillator neutron detector as an improved alternative to the standard 3 he proportional counter  

SciTech Connect

Lithium glass scintillator made from 6Li-enriched substrate is a well known for its neutron detection capability. In spite of neutron interaction, cross section of 6Li happens to be lower than that of 3He. However, the neutron detection efficiency could be higher due to higher volume content of 6Li nuclear in the solid scintillator vs. gas filled proportional counter. At the same time, as lithium glass is sensitive to gamma and charge particle radiation, non-neutron radiation discrimination is required. Our detector is composed of two equal-size cylindrical Li(Ce) glass scintillators. The first one is high-sensitive to thermal neutrons GS-20 (6Li doped), the second one is GS-30 (7Li doped) type Scint-Gobain made lithium glass scintillator. Each of scintillators is coupled with R7400U Hamamatsu subminiature photomultiplier tube, and all assembly is fitted into NP100H 3He tube size. 6Li absorbs thermal neutrons releasing alpha particles and triton with 4.8 MeV total energy deposit inside the scintillator (equivalent to about ~1.3 MeV gamma energy depositions). Because 7Li isotope does not absorb thermal neutrons, and the physical properties of the two scintillators are virtually identical, the difference between these two scintillators could be used to provide neutron dose rate information. Results of study of neutron detector assembled of two Li(Ce) scintillators and NP100H moderator are presented

Vladimir Popov, Pavel Degtiarenko

2011-06-01

120

Segmented scintillation detectors with silicon photomultiplier readout for measuring antiproton annihilations  

NASA Astrophysics Data System (ADS)

The Atomic Spectroscopy and Collisions Using Slow Antiprotons experiment at the Antiproton Decelerator (AD) facility of CERN constructed segmented scintillators to detect and track the charged pions which emerge from antiproton annihilations in a future superconducting radiofrequency Paul trap for antiprotons. A system of 541 cast and extruded scintillator bars were arranged in 11 detector modules which provided a spatial resolution of 17 mm. Green wavelength-shifting fibers were embedded in the scintillators, and read out by silicon photomultipliers which had a sensitive area of 1 × 1 mm2. The photoelectron yields of various scintillator configurations were measured using a negative pion beam of momentum p ? 1 GeV/c. Various fibers and silicon photomultipliers, fiber end terminations, and couplings between the fibers and scintillators were compared. The detectors were also tested using the antiproton beam of the AD. Nonlinear effects due to the saturation of the silicon photomultiplier were seen at high annihilation rates of the antiprotons.

Sótér, A.; Todoroki, K.; Kobayashi, T.; Barna, D.; Horváth, D.; Hori, M.

2014-02-01

121

Segmented scintillation detectors with silicon photomultiplier readout for measuring antiproton annihilations.  

PubMed

The Atomic Spectroscopy and Collisions Using Slow Antiprotons experiment at the Antiproton Decelerator (AD) facility of CERN constructed segmented scintillators to detect and track the charged pions which emerge from antiproton annihilations in a future superconducting radiofrequency Paul trap for antiprotons. A system of 541 cast and extruded scintillator bars were arranged in 11 detector modules which provided a spatial resolution of 17 mm. Green wavelength-shifting fibers were embedded in the scintillators, and read out by silicon photomultipliers which had a sensitive area of 1 × 1 mm(2). The photoelectron yields of various scintillator configurations were measured using a negative pion beam of momentum p ? 1 GeV/c. Various fibers and silicon photomultipliers, fiber end terminations, and couplings between the fibers and scintillators were compared. The detectors were also tested using the antiproton beam of the AD. Nonlinear effects due to the saturation of the silicon photomultiplier were seen at high annihilation rates of the antiprotons. PMID:24593349

Sótér, A; Todoroki, K; Kobayashi, T; Barna, D; Horváth, D; Hori, M

2014-02-01

122

Thin film techniques for developing a more rugged alpha scintillation detector  

SciTech Connect

The objective of this project was to develop an alpha scintillation detector more rugged than conventional detectors having aluminized Mylar entrance windows, which can be damaged in some hostile environments encountered in field surveys. A more durable, light- tight entrance window will reduce maintenance costs. This developmental model consists of a thin sandwich of scintillator, opaque material, and scuff-resistant coating deposited on a transparent substrate. Several scintillators have been evaluated for light output and high alpha-to-gamma ratio. After optimizing the thickness of the scintillator, the layer is made opaque to ambient light by coating the front side with a light-tight material such as aluminum. The opaque entrance window is protected with a scuff-resistant layer of silicon dioxide, and the finished wafer is attached to a photomultiplier tube to complete the detector assembly. 6 refs., 7 figs.

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

1988-01-01

123

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

124

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

125

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 > 10 keV. The energy of the gamma rays used in scintigraphic imaging never exceeds 511 keV. Interaction cross-sections for energies between 10 keV and 10 MeV 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 2.5 mm (FWHM) for a 6 mm NaI(Tl) thickness and gamma rays of 140 keV. 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

126

Modeling of a Directional Scintillating Fiber Detector for 14 MeV Neutrons  

Microsoft Academic Search

The GEANT4 Monte Carlo simulation tool was used to model a prototype 14 MeV neutron fiber detector. Detail features of the prototype were implemented in the modeling to assess the directionality and detector performance. The prototype was built using plastic fibers consisting of a core scintillating material and an acrylic outer cladding. A total of 64 square fibers were used

W. Mengesha; N. Mascarenhas; J. Peel; D. Sunnarborg

2006-01-01

127

DQE measurement in a scintillating glass optical fiber detector for X-ray imaging  

Microsoft Academic Search

An example of the measurement of detective quantum efficiency is illustrated for a scintillating glass optical fiber detector used in X-ray imaging. We have shown the necessity to filter the input Poisson noise of the incoming beam, by the MTF (Modulation Transfer Function) of the detector, in order to obtain the real DQE (Detective Quantum Efficiency).

S. Costa; P. Ottonello; G. A. Rottigni; G. Zanella; R. Zannoni

1996-01-01

128

Development of a scintillator detector system for ?-ray scan measurements of industrial distillation columns  

Microsoft Academic Search

A CsI(Tl) scintillator detector set was developed for ?-ray scan measurements aiming to identify process failures in distillation columns of an industrial petrochemical plant. A system with a 60Co sealed source as a ?-ray emitter and the developed CsI(Tl) detector were applied to evaluate the performances in a simulated model of a tray-type distillation column.

Pablo A. Vásquez S; Fabio E. Costa; Wilson A. P. Calvo; Margarida M. Hamada

2005-01-01

129

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

130

Characterization of Detector Scintillator Effect on Interventional Device Visualization in X-ray Fluoroscopy  

Microsoft Academic Search

Flat panel detectors have a large number of parameters that affect fluoroscopy image quality. Scintillator thickness is very important and can be readily changed in fabrication. With increasing thickness, there is a degradation of MTF with spatial blurring but improved conversion efficiency. This design trade-off should be optimized for visualization. Using quantitative experimental and techniques, we simulated three detector models,

Yuhao Jiang; David L. Wilson

2005-01-01

131

Characterization of detector scintillator effect on interventional device visualization in x-ray fluoroscopy  

Microsoft Academic Search

Flat panel detectors have a large number of parameters that affect fluoroscopy image quality. Scintillator thickness is very important and can be changed in fabrication. In general, with increasing thickness, there is a degradation of MTF with spatial blurring but improved conversion efficiency. This design trade-off should be optimized for visualization. Using quantitative experimental and techniques, we simulated three detector

Yuhao Jiang; David L. Wilson

2005-01-01

132

Results from Noble Gas Scintillation Detectors with Solid State Light Readout  

NASA Astrophysics Data System (ADS)

A proof of concept is delivered regarding the performance and feasibility of using silicon photomultiplier (SiPM) solid state light readout devices in noble gas scintillation detectors. By immersing SiPMs directly in the scintillating gas, light collection values can be achieved that are highly competitive with those of PMT based detectors. The work further shows that pulse shape discrimination information is accessible even with the SiPM readout. This proof of concept opens the door for the design of highly rugged, low cost, high performance detectors.

Chandra, Rico; Davatz, Giovanna; Gendotti, Ulisse; Caccia, Massimo; Chmill, Valery; Martemiyanov, Sasha; Santoro, Romualdo

2014-02-01

133

Theoretical study of three-dimensionally position-sensitive scintillation detector based on continuous crystal  

NASA Astrophysics Data System (ADS)

In the field of nuclear imaging (PET, Compton camera, etc.) the application of detectors that are position sensitive in all the three dimensions could increase spatial resolution of images by avoiding the parallax error. In the present paper the viability of a three-dimensionally position-sensitive scintillation detector using continuous scintillator crystal is theoretically studied. The feasibility of building such a detector is based on the recognition that both the spatial position and the radiant flux of a point-like isotropic radiation source can be determined by performing flux density measurements at four appropriately selected points of the space. On the basis of this one can construct a position-sensitive scintillation detector where the scintillation crystal is surrounded with four or more photodetectors, supposing that the point of interaction (POI) of the gamma ray within the scintillator could be considered as a point-like isotropic light source. The POI coordinates can then be determined relying on the finding that the ratio of two arbitrary linear combinations of the photodetector responses is equal to the same ratio constructed from the solid angles subtended by the photodetectors as seen from the POI. The results of theoretical calculations describing the relations between the photodetector responses and the spatial coordinates of the POI are presented for three different photodetector-scintillator combinations.

Gál, J.; Kalinka, G.; Nyakó, B. M.

2009-08-01

134

Simulating response functions and pulse shape discrimination for organic scintillation detectors with Geant4  

NASA Astrophysics Data System (ADS)

We present new capabilities of the Geant4 toolkit that enable the precision simulation of organic scintillation detectors within a comprehensive Monte Carlo code for the first time. As of version 10.0-beta, the Geant4 toolkit models the data-driven photon production from any user-defined scintillator, photon transportation through arbitrarily complex detector geometries, and time-resolved photon detection at the light readout device. By fully specifying the optical properties and geometrical configuration of the detector, the user can simulate response functions, photon transit times, and pulse shape discrimination. These capabilities enable detector simulation within a larger experimental environment as well as computationally evaluating novel scintillators, detector geometry, and light readout configurations. We demonstrate agreement of Geant4 with the NRESP7 code and with experiments for the spectroscopy of neutrons and gammas in the ranges 0-20 MeV and 0.511-1.274 MeV, respectively, using EJ301-based organic scintillation detectors. We also show agreement between Geant4 and experimental modeling of the particle-dependent detector pulses that enable simulated pulse shape discrimination.

Hartwig, Zachary S.; Gumplinger, Peter

2014-02-01

135

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

2011-02-01

136

Performance of an electromagnetic lead\\/scintillating-fibre calorimeter for the H1 detector  

Microsoft Academic Search

The properties of final modules of a high resolution lead\\/scintillating-fibre calorimeter to upgrade the backward region of the H1 detector were studied with electrons in the energy range from 2–60 GeV. The electromagnetic calorimeter consists of scintillating fibres with a diameter of 0.5 mm embedded in a lead matrix. This small fibre radius, in combination with a lead-to-fibre ratio of

T. Nicholls; L. Hajduk; W. Janczur; K. Rybicki; B. Claxton; J. Dowdell; H. Deckers; T. Deckers; M. Dirkmann; M. Hütte; H. Hutter; H. Kolanoski; R. Pöschl; A. Schuhmacher; K. Wacker; A. Walther; D. Wegener; T. Wenk; G. Cozzika; B. Laforge; J.-F Laporte; E. Perez; C. Royon; G. Villet; R. D Appuhn; C. Arndt; R. Barschke; R. Buchholz; U. Goerlach; V. Korbel; F. Lehner; A. Meyer; G. Müller; H. Steiner; M. Weber; J. Ferencei; J. Janoth; K. Meier; S. Schleif; J. Stiewe; K. Zuber; W. D Dau; D. Bruncko; F. Krivan; R. Maracek; P. Murin; J. Spalek; E. Eisenhandler; M. Landon; L. Jönsson; S. Chechelnitski; V. Efremenko; B. Fominykh; I. Gorelov; V. Nagovizin; D. Ozerov; A. Rostovtsev; V. Shekelyan; A. Semenov; V. Solochenko; V. Tchernyshov; A. Zhokin; A. N Eliseev; L. A Gorbov; P. A Smirnov; F. Lamarche; A. Migliori; F. Moreau; Y. Sirois; S. Spielmann; D. Vandenplas; E. Barrelet; U. Bassler; S. Dagoret-Campagne; F. Descamps; D. Lacour; J. Cvach; I. Herynek; J. Hladky; S. Valkar; J. Zacek

1996-01-01

137

High energy gamma-ray spectroscopy with LaBr 3 scintillation detectors  

Microsoft Academic Search

Lanthanum bromide scintillation detectors produce very high light outputs (?60,000ph\\/MeV) within a very short decay time (typically ?20ns) which means that high instantaneous currents can be generated in the photocathode and dynode chain of the photomultiplier tube (PMT) used for the scintillation readout. The net result is that signal saturation can occur long before the recommended PMT biasing conditions can

F. G. A. Quarati; Alan Owens; P. Dorenbos; J. T. M. de Haas; G. Benzoni; N. Blasi; C. Boiano; S. Brambilla; F. Camera; R. Alba; G. Bellia; C. Maiolino; D. Santonocito; M. Ahmed; N. Brown; S. Stave; H. R. Weller; Y. K. Wu

2011-01-01

138

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

139

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

140

Digital pulse-shape algorithms for scintillation-based neutron detectors  

Microsoft Academic Search

We discuss the application of digital pulse shape algorithms to n\\/? pulse shape discrimination (PSD) in boron-10 enriched liquid scintillator, where the use of digital techniques has potential applications for neutron monitors. High-speed flash analog-to-digital converters have opened up new possibilities for scintillator detector systems based upon digital event-by-event data acquisition. Using an 8-bit 1-GS\\/s waveform digitizer, we sampled the

S. D. Jastaniah; P. J. Sellin

2002-01-01

141

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

142

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

143

Developments of directional detectors with NaI(Tl)/BGO scintillators  

NASA Astrophysics Data System (ADS)

This paper describes directional gamma ray detectors with different types of scintillators. The detectors, which positively increase directional sensitivity to incident gamma rays, have been developed to measure directions, energies and counts of gamma rays, and to search for radioactive materials such as orphan radioisotopes or contaminations. Experimental results have shown that proposed directional detectors have a potential for practical use in real fields and will contribute to radiation protection and safety.

Shirakawa, Y.

2004-01-01

144

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

145

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

SciTech Connect

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 {gamma}-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; Quan Lin; Zhang Zhongbing [Radiation Detection Research Center, Northwest Institute of Nuclear Technology, P.O. Box 69-9, Xi'an, Shaanxi 710024 (China); Ouyang Xiaoping [Radiation Detection Research Center, Northwest Institute of Nuclear Technology, P.O. Box 69-9, Xi'an, Shaanxi 710024 (China); School of Nuclear Science and Engineering, North China Electric Power University, Beijing 102206 (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Liu Bin [School of Nuclear Science and Engineering, North China Electric Power University, Beijing 102206 (China); Liu Jinliang [Radiation Detection Research Center, Northwest Institute of Nuclear Technology, P.O. Box 69-9, Xi'an, Shaanxi 710024 (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

2013-01-15

146

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

147

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

148

Characterizing the response of miniature scintillation detectors when irradiated with proton beams.  

PubMed

Designing a plastic scintillation detector for proton radiation therapy requires careful consideration. Most of the plastic scintillators should not perturb a proton beam if they are sufficiently small but may exhibit some energy dependence due to the quenching effect. In this work, we studied the factors that would affect the performance of such scintillation detectors. We performed Monte Carlo simulations of proton beams with energies between 50 and 250 MeV to study signal amplitude, water equivalence, spatial resolution and quenching of light output. Implementation of the quenching effect in the Monte Carlo simulations was then compared with prior experimental data for validation. The signal amplitude of a plastic scintillating fiber detector was on the order of 300 photons per MeV of energy deposited in the detector, corresponding to a power of about 30 pW at a proton dose rate of 100 cGy min(-1). The signal amplitude could be increased by up to a factor of 2 with reflective coating. We also found that Cerenkov light was not a significant source of noise. Dose deposited in the plastic scintillator was within 2% of the dose deposited in a similar volume of water throughout the whole depth-dose curve for protons with energies higher than 50 MeV. A scintillation detector with a radius of 0.5 mm offers a sufficient spatial resolution for use with a proton beam of 100 MeV or more. The main disadvantage of plastic scintillators when irradiated by protons was the quenching effect, which reduced the amount of scintillation and resulted in dose underestimation by close to 30% at the Bragg peak for beams of 150 MeV or more. However, the level of quenching was nearly constant throughout the proximal half of the depth-dose curve for all proton energies considered. We therefore conclude that it is possible to construct an effective detector to overcome the problems traditionally encountered in proton dosimetry. Scintillation detectors could be used for surface or shallow measurements with a single calibration for specific beam energy. For deeper measurements, Monte Carlo simulations can be used to generate depth-dependent correction factors. PMID:18364543

Archambault, Louis; Polf, Jerimy C; Beaulieu, Luc; Beddar, Sam

2008-04-01

149

Simulation, Test und Konstruktion des Szintillationsdetektors AMADEUS 2. (Simulation, test and construction of the scintillation detector AMADEUS 2).  

National Technical Information Service (NTIS)

A compact scintillation detector (AMADEUS) is described, which allows particle identification and the complete determination of the particle four-momentum vector. The behaviour of the detector is studied by a Monte-Carlo-simulation. With the help of this ...

J. Hey

1991-01-01

150

Directional Neutron Detectors for use with 14 MeV Neutrons. Fiber Scintillation Methods for Directional Neutron Detection.  

National Technical Information Service (NTIS)

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 prototyp...

N. Mascarenhas J. D. Peel D. Sunnarborg W. Mengesha

2005-01-01

151

A scintillating gas detector for 2D dose measurements in clinical carbon beams  

NASA Astrophysics Data System (ADS)

A two-dimensional position sensitive dosimetry system based on a scintillating gas detector has been developed for pre-treatment verification of dose distributions in hadron therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside which two cascaded gas electron multipliers (GEMs) are mounted. A GEM is a thin kapton foil with copper cladding structured with a regular pattern of sub-mm holes. The primary electrons, created in the detector's sensitive volume by the incoming beam, drift in an electric field towards the GEMs and undergo gas multiplication in the GEM holes. During this process, photons are emitted by the excited Ar/CF4 gas molecules and detected by a mirror-lens-CCD camera system. Since the amount of emitted light is proportional to the dose deposited in the sensitive volume of the detector by the incoming beam, the intensity distribution of the measured light spot is proportional to the 2D hadron dose distribution. For a measurement of a 3D dose distribution, the scintillating gas detector is mounted at the beam exit side of a water-bellows phantom, whose thickness can be varied in steps. In this work, the energy dependence of the output signal of the scintillating gas detector has been verified in a 250 MeV/u clinical 12C ion beam by means of a depth-dose curve measurement. The underestimation of the measured signal at the Bragg peak depth is only 9% with respect to an air-filled ionization chamber. This is much smaller than the underestimation found for a scintillating Gd2O2S:Tb ('Lanex') screen under the same measurement conditions (43%). Consequently, the scintillating gas detector is a promising device for verifying dose distributions in high LET beams, for example to check hadron therapy treatment plans which comprise beams with different energies.

Seravalli, E.; de Boer, M.; Geurink, F.; Huizenga, J.; Kreuger, R.; Schippers, J. M.; van Eijk, C. W. E.; Voss, B.

2008-09-01

152

Comparative Investigation of the Performance of ZnO-Based Scintillators for Use as ?-Particle Detectors  

SciTech Connect

As part of a comprehensive investigation of the scintillation properties of zinc-oxide-based scintillators, four samples of gallium-doped zinc oxide (ZnO) powders have been characterized by means of X-ray excitation, {alpha}-particle excitation, and temperature-dependent photoluminescence (PL). The ultimate goals of these studies are, first, to understand the scintillation mechanisms that are operative in various members of the ZnO family of scintillators, and, subsequently, to use this knowledge in order to improve the radiation-detection performance of ZnO. These samples have been considered for use in an {alpha}-detector for installation in a deuterium-tritium (D-T) neutron generator. All of the samples demonstrated principal decay time components on the order of 1 ns. PL measurements of the four powder samples did not unequivocally support any of the discussed models. Excitonic and shallow acceptor models, however, share a common starting point for future investigations. The Lawrence Berkeley National Laboratory (LBNL) 3518 sample was found to be the most promising candidate, in terms of fast light output, for replacing the Nuclear Enterprises Technology sample for use in a ZnO:Ga-based {alpha}-particle detector. While the nature of the luminescence center(s) or the energy transfer mechanisms actually responsible for scintillation are not yet clearly understood, ZnO:Ga remains a highly desirable candidate scintillator for use in an {alpha}-detector for installation in a D-T neutron generator and extended investigations of the fundamental mechanisms and scintillation parameters that are operative in ZnO:Ga scintillators are continuing.

Neal, John S [ORNL; Boatner, Lynn A [ORNL; Giles, N. C. [West Virginia University; Halliburton, L. E. [West Virginia University; Derenzo, S. E. [Lawrence Berkeley National Laboratory (LBNL); Bourret-Courchesne, E. D. [Lawrence Berkeley National Laboratory (LBNL)

2006-01-01

153

Scintillator Detectors for Scanning Transmission X-ray Microscopes at the Advanced Light Source  

SciTech Connect

The choice of x-ray detectors presents a challenge for scanning transmission x-ray microscopes (STXM). The ultimate detector for the ALS STXMs should have a very high efficiency over a wide energy range, single photon counting capabilities up to 1GHz, high rejection of red laser light, fast response, and work in both vacuum and at atmospheric pressure. The results of an investigation using a photomultiplier tube (PMT) with a number of different scintillators are presented. The PMT is used in photon counting and analog modes. Scintillators used for this study include commercially available phosphor powders and various single crystals.

Fakra, S.; Tyliszczak, T. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kilcoyne, A.L.D. [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2004-05-12

154

Observation of EAS Core with the Small Scintillation Detector at Taro  

NASA Astrophysics Data System (ADS)

We have observed the core structure of extensive air showers(EAS) that primary energy above 1016 eV. To measure the more detail and the correct density of the incident particles near EAS core, we installed 100 small scintillation detectors (using plastic scintillator : 15cm × 15cm × 2.5cm) that are placed on a lattice 10 × 10, and 40cm separation, at Taro Cosmic Ray Lab oratory, at autumn 2002. We report the detail of the small detector, and preliminary results.

Sakuyama, H.; Kuramochi, Hiroshi; Obara, Hitoshi; Ono, Shunichi; Origasa, Satoru; Mochida, Akinori; Sakayama, Hiroshi; Suzuki, Noboru

2003-07-01

155

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

156

First-principles Electronic Structure Calculations for Scintillation Phosphor Nuclear Detector Materials  

NASA Astrophysics Data System (ADS)

Inorganic scintillation phosphors (scintillators) are extensively employed as radiation detector materials in many fields of applied and fundamental research such as medical imaging, high energy physics, astrophysics, oil exploration and nuclear materials detection for homeland security and other applications. The ideal scintillator for gamma ray detection must have exceptional performance in terms of stopping power, luminosity, proportionality, speed, and cost. Recently, trivalent lanthanide dopants such as Ce and Eu have received greater attention for fast and bright scintillators as the optical 5d to 4f transition is relatively fast. However, crystal growth and production costs remain challenging for these new materials so there is still a need for new higher performing scintillators that meet the needs of the different application areas. First principles calculations can provide a useful insight into the chemical and electronic properties of such materials and hence can aid in the search for better new scintillators. In the past there has been little first-principles work done on scintillator materials in part because it means modeling f electrons in lanthanides as well as complex excited state and scattering processes. In this talk I will give an overview of the scintillation process and show how first-principles calculations can be applied to such systems to gain a better understanding of the physics involved. I will also present work on a high-throughput first principles approach to select new scintillator materials for fabrication as well as present more detailed calculations to study trapping process etc. that can limit their brightness. This work in collaboration with experimental groups has lead to the discovery of some new bright scintillators.

Canning, Andrew

2013-03-01

157

Neutron detectors on the basis of lithium scintillation glasses  

Microsoft Academic Search

An optimization of lithium scintillation glasses composition was carried out. The glasses obtained were then tested for neutrons detection. It was established that glasses of optimised composition are characterised by heightened light output as compared with well known glass NE-905. Amplitude resolution by the neutrons registration is not graiter than 18%.

V. I Arbuzov; N. Z Andreeva; V. A Vitenko; M. A Milovidov

1995-01-01

158

Scintillator purification, detector performance and first results from Borexino  

Microsoft Academic Search

The Borexino experiment has begun data taking in May 2007 after a long R&D work and preparation. The liquid scintillator purity exceeds even optimistic expectations, and the first detection of 7Be solar neutrinos has been possible after less than two months of data taking. This note shows briefly which are the main issues that were addressed in order to obtain

M. Pallavicini; G. Bellini; J. Benziger; S. Bonetti; B. Caccianiga; F. Calaprice; F. Dalnoki-Veress; D. D'Angelo; H. de Kerret; A. Derbin; A. Etenko; K. Fomenko; R. Ford; D. Franco; C. Galbiati; S. Gazzana; M. Giammarchi; M. Goeger-Neff; A. Goretti; C. Grieb; S. Hardy; G. Heusser; A. Ianni; M. Joyce; G. Korga; D. Kryn; M. Laubenstein; M. Leung; E. Litvinovich; P. Lombardi; L. Ludhova; I. Machulin; G. Manuzio; F. Masetti; K. McCarty; E. Meroni; L. Miramonti; M. Misiaszek; D. Montanari; M. E. Monzani; V. Muratova; L. Niedermeier; L. Oberauer; M. Obolensky; F. Ortica; L. Papp; L. Perasso; A. Pocar; R. S. Raghavan; G. Ranucci; A. Razeto; A. Sabelnikov; C. Salvo; S. Schönert; H. Simgen; O. Smirnov; M. Skorokhvatov; A. Sonnenschein; A. Sotnikov; S. Sukhotin; Y. Suvorov; V. Tarasenkov; R. Tartaglia; G. Testera; D. Vignaud; R. B. Vogelaar; F. von Feilitzsch; M. Wojcik; O. Zaimidoroga; S. Zavatarelli; G. Zuzel

2008-01-01

159

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

160

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

161

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

162

A fast microchannel plate-scintillator detector for velocity map imaging and imaging mass spectrometry.  

PubMed

The time resolution achievable using standard position-sensitive ion detectors, consisting of a chevron pair of microchannel plates coupled to a phosphor screen, is primarily limited by the emission lifetime of the phosphor, around 70 ns for the most commonly used P47 phosphor. We demonstrate that poly-para-phenylene laser dyes may be employed extremely effectively as scintillators, exhibiting higher brightness and much shorter decay lifetimes than P47. We provide an extensive characterisation of the properties of such scintillators, with a particular emphasis on applications in velocity-map imaging and microscope-mode imaging mass spectrometry. The most promising of the new scintillators exhibits an electron-to-photon conversion efficiency double that of P47, with an emission lifetime an order of magnitude shorter. The new scintillator screens are vacuum stable and show no signs of signal degradation even over longer periods of operation. PMID:24593353

Winter, B; King, S J; Brouard, M; Vallance, C

2014-02-01

163

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

PubMed

Conventionally, block detectors, which consist of a two-dimensionally segmented scintillator array with inserted reflectors, are often used for PET. On the other hand, PET detectors with a monolithic block have been investigated because they are expected to offer higher resolution than do segmented crystal arrays. However, previous reports focused on detectors dedicated as small-animal PET, and the thickness was not good enough to stop 511-keV radiation. We developed a PET detector that uses a large and thick monolithic LYSO and 64-channel PS-PMT. When the LYSO was covered with reflectors, the spatial resolution, which was 3 mm FWHM at the center, rapidly became worse at the edge. We eliminated the loss of spatial resolution by replacing the reflectors with black paper, but the light output was decreased. Therefore, we concluded that spatial resolution and light output were in a trade-off relationship due to the edge effect of scintillation light. PMID:21340540

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

2011-07-01

164

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

165

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

166

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

167

Design And Performance Of Optical Detectors Fabrication Setup Using Pulsed Laser Deposition (PLD)  

SciTech Connect

PLD system was used in the preparation of nano structured thin layers to be used as optical detectors. Our home made on--axis PLD setup utilizes XeCl excimer laser (308 nm, Pulse duration of 7 ns, repetition rate of 200 Hz). The laser energy is kept at 8 mj, and the vacuum chamber has been pumped to a background pressure of 10{sup -5} mbar. The films can be grown at different substrate temperatures in the range of 25-400 deg. C. The substrate temperature was always kept below 400 deg. C by using advanced temperature control system. The target-to-substrate distance was variable from 2 to 6 cm. SiO{sub 2} was used as substrates because of its low refractive index and high transparency in the UV, visible and near infrared ranges of spectra. LIPS technique has been used for plasma diagnoses during film deposition, using a double monochromator provided with photon detector. Homogenous thin films in the order of 20-200 nm thickness were obtained. Moreover, both amorphous and crystalline thin films can be obtained by adjusting the substrate temperature, target--substrate distance, type of substrate and finally pressure of ambient gas.

Aboulfotouh, N.; Moharm, B. [Faculty of Engineering, Tanta University, Tanta (Egypt); El Magd, A. Abou; Atta, M.; Badr, Y. [National Institute of Laser Enhanced Science, Cairo University (Egypt)

2009-09-27

168

Optical coupling between scintillators and standard CMOS detectors  

Microsoft Academic Search

In the digital X-ray imaging systems, one of the main problems to be solved is the efficiency of the optical interfaces between scintillators and photodetectors. This article presents the theoretical analysis, simulations, and experimental results on two different optical interfaces (SiO2 and Si3N4), in order to maximize the X-ray detection efficiency. The working principle is the following: the X-ray photons

J. G. Rocha; G. Minas; S. Lanceros-Mendez

2006-01-01

169

A time-gating scintillation detector for the measurement of laser-induced fast neutrons  

SciTech Connect

A time-gating scintillation detector, in which a fast high voltage switch is used for gating a channel photomultiplier, was developed for a measurement of laser-induced fast neutrons. The x rays generated from the intense femtosecond laser and the solid target interactions were suppressed selectively and a time-of-flight signal of a laser-generated fast neutron was measured effectively. The detector was used successfully to measure the neutron yield of a femtosecond, deuterated, polystyrene plasma.

Lee, Sungman; Park, Sangsoon; Yea, Kwon-hae; Cha, Hyungki [Quantum Optics Division, Korea Atomic Energy Research Institute, Daejeon 305-600 (Korea, Republic of)

2009-06-15

170

Optimization of scintillation-detector timing systems using Monte Carlo analysis  

Microsoft Academic Search

Monte Carlo analysis is used to model statistical noise associated with scintillation-detector photoelectron emissions and photomultiplier tube operation. Additionally, the impulse response of a photomultiplier tube, front-end amplifier, and constant-fraction discriminator (CFD) is modeled so the effects of front-end bandwidth and constant-fraction delay and fraction can be evaluated for timing-system optimizations. Such timing-system analysis is useful for detectors having low

David M. Binkley

1994-01-01

171

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

172

An activated charcoal-based, liquid scintillation-analyzed airborne Rn detector  

SciTech Connect

An inexpensive, easy-to-use detector for measuring airborne /sup 222/Rn based on /sup 222/Rn diffusion and absorption in activated charcoal is presented. The detector uses chemical extraction and liquid scintillation for measurement of the /sup 222/Rn concentration, is designed to be insensitive to temperature and humidity effects, and obtains sensitivity levels of 675 CPM (Bq L-1)-1 (25 CPM (pCi L-1)-1) at room temperature.

Schroeder, M.C.; Vanags, U.; Hess, C.T.

1989-07-01

173

A Scintillator tile-fiber preshower detector for the CDF Central Calorimeter  

SciTech Connect

The front face of the CDF central calorimeter is being equipped with a new Preshower detector, based on scintillator tiles read out by WLS fibers. A light yield of about 40 pe/MIP at the tile exit was obtained, exceeding the design requirements.

S. Lami

2004-08-12

174

Time resolution and linearity measurements for a scintillating fiber detector instrumented with VLPCs  

Microsoft Academic Search

The time resolution for charged particle detection is reported for a typical scintillating fiber detector instrumented with Rockwell HISTE-IV Visible Light Photon Counters (VLPC). The resolution measurements are shown to agree with a simple Monte-Carlo model, and the model is used to make recommendations for improved performance. In addition, the gain linearity of a sample of VLPC devices was measured.

Alan Bross; Ana Lucia Chaves; Jesse Costa; Marvin Johnson; Lourival Moreira; Joey Thompson

1997-01-01

175

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

176

A scintillation triggering unit for a liquid-argon neutrino detector. Structure  

SciTech Connect

A scintillator system consisting of 48 planes with a total area of about 230 m{sup 2} for a liquid-argon neutrino detector is described. The light output, time resolution, and efficiency of the units are presented. Cosmic rays have been detected with a time resolution of 4.5 to 5 nsec. The testing procedures during the assembly are described.

Belikov, S.V.; Gurzhiev, S.N.; Kochetkov, V.I.; Startsev, V.S. [Institute of High-Energy Physics, Serpukhov, Moscow (Russian Federation)

1994-05-01

177

Position sensitive x- and gamma-ray scintillator detector for new space telescopes  

NASA Astrophysics Data System (ADS)

The instruments on board the latest gamma observatories (INTEGRAL, SWIFT, AGILE, GLAST) combines technologies based on solid state and on scintillator detector, the first one being favorite when a low energy threshold and a good energy resolution is required, the latter being more convenient for large volume when worse performance are still acceptable. With the developments achieved both with the new scintillator material and even more with new low-noise light readout devices the differences between the two techniques are narrowing and for some application the cheaper scintillator detector can compete with solid state devices. Starting from the techniques used in INTEGRAL-IBIS and AGILE a new generation position sensitive X and gamma ray detector based on scintillator with Silicon Drift Chamber readout has been developed and tested. The ASIC read-out electronics make it suitable for replication in a large scale when a great number of pixel is needed. The performance of the detector as well as its applications in new generation space telescopes are presented and discussed.

Labanti, C.; Marisaldi, M.; Fuschino, F.; Bastia, P.; Negri, B.; Perotti, F.; Soltau, H.

2008-08-01

178

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

179

Setup to investigate rare neutron producing processes  

NASA Astrophysics Data System (ADS)

An experimental setup has been created to study rare processes with neutron production. The detecting system comprises a scintillation detector in the form of a cup around which thermal neutron detectors ( BF3 counters) set in paraffin are placed parallel to the common axis in two concentric circles. The detecting system and registering electronics make it possible to obtain time and amplitude information for each registered event.

Bystritsky, V. M.; Zhuravlev, N. I.; Merzlyakov, S. I.; Sidorov, V. T.; Stolupin, V. A.; Strelkov, A. V.; Shvetsov, V. N.

1996-02-01

180

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

181

Design of a high resolution scintillator based SPECT detector (SPECTatress)  

Microsoft Academic Search

SPECT scanners using multi-pinhole collimators benefit from compact detectors having a high spatial resolution. Such detectors can be placed closer to the collimator and perpendicular to the pinhole axis (thereby limiting DOI spatial resolution degradation). Current clinical gamma ray cameras have a large area and a poor spatial resolution.This proceeding describes the architecture of SPECTatress, a compact high resolution gamma

Karel Deprez; Roel Van Holen; Stefaan Vandenberghe; Steven Staelens

2011-01-01

182

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

183

Study of light transport inside scintillation crystals for PET detectors  

NASA Astrophysics Data System (ADS)

Scintillation crystal design is a critical component in positron emission tomography system development, which impacts a number of performance parameters including energy resolution, time resolution and spatial resolution. Our work aims to develop a generalized simulation tool to model the light transport inside scintillation crystals with good accuracy, taking into account surface treatments, reflectors, temporal dependence of scintillation decay, and comprehensive experimental validations. The simulation has been validated against both direct analytical calculation and experimental measurements. In this work, the studies were performed for a lutetium-yttrium oxyorthosilicate crystal of 3×3×20 mm3 dimension coupled to a Hamamatsu silicon photomultiplier, with respect to light output, rise-time slope, energy resolution and time resolution. Four crystal surface treatment and reflector configurations were investigated: GroundMetal, GroundPaint, PolishMetal and PolishPaint. The experiments were performed to validate the Monte Carlo simulation results. The results indicate that the best time resolution (0.96±0.05 ns) and good energy resolution (10.6±0.4%) could be produced by using a polished surface with specular reflector, while the configuration of a polished surface with diffusive reflector produces the best energy resolution (10.2±0.9%). The results indicate that a polished surface with diffusive reflector achieves the best energy resolution (10.2±0.9%) for 511 keV high energy photons, and a polished surface with specular reflector achieves the best time resolution (0.96±0.05 ns) measured against a Hamamatsu fast photomultiplier tube. The ground surface treatment is not recommended for its inferior performance in terms of energy and time resolution. Possible explanations and future improvements to be made to the developed simulation tool are discussed.

Yang, Xin; Downie, Evan; Farrell, Thomas; Peng, Hao

2013-04-01

184

Study of light transport inside scintillation crystals for PET detectors.  

PubMed

Scintillation crystal design is a critical component in positron emission tomography system development, which impacts a number of performance parameters including energy resolution, time resolution and spatial resolution. Our work aims to develop a generalized simulation tool to model the light transport inside scintillation crystals with good accuracy, taking into account surface treatments, reflectors, temporal dependence of scintillation decay, and comprehensive experimental validations. The simulation has been validated against both direct analytical calculation and experimental measurements. In this work, the studies were performed for a lutetium-yttrium oxyorthosilicate crystal of 3×3×20 mm(3) dimension coupled to a Hamamatsu silicon photomultiplier, with respect to light output, rise-time slope, energy resolution and time resolution. Four crystal surface treatment and reflector configurations were investigated: GroundMetal, GroundPaint, PolishMetal and PolishPaint. The experiments were performed to validate the Monte Carlo simulation results. The results indicate that the best time resolution (0.96±0.05 ns) and good energy resolution (10.6±0.4%) could be produced by using a polished surface with specular reflector, while the configuration of a polished surface with diffusive reflector produces the best energy resolution (10.2±0.9%). The results indicate that a polished surface with diffusive reflector achieves the best energy resolution (10.2±0.9%) for 511 keV high energy photons, and a polished surface with specular reflector achieves the best time resolution (0.96±0.05 ns) measured against a Hamamatsu fast photomultiplier tube. The ground surface treatment is not recommended for its inferior performance in terms of energy and time resolution. Possible explanations and future improvements to be made to the developed simulation tool are discussed. PMID:23470488

Yang, Xin; Downie, Evan; Farrell, Thomas; Peng, Hao

2013-04-01

185

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

186

Thin photodiodes for a scintillation-silicon well detector  

SciTech Connect

In developing position sensitive radiation sensors, e.g., for medical imaging, low-gain silicon well sensors were made for the detection of scintillation light. The 3 x 3 arrays induce N++NP diodes, processed in the {approximately}12 {micro}m thick membranes that remain after thinning of 530 {micro}m thick (100) silicon wafers by means of a potassium hydroxide (KOH) solution. A comparison is made for the light detection efficiency of these diodes with that of a 500 {mu}m thick PIN photodiode.

Allier, C.P.; Hollander, R.W.; Sarro, P.M.; Eijk, C.W.E. van

1999-12-01

187

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

188

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

189

Fast calibration of SPECT monolithic scintillation detectors using un-collimated sources.  

PubMed

Monolithic scintillation detectors for positron emission tomography and single-photon emission computed tomography (SPECT) imaging have many advantages over pixelated detectors. The use of monolithic crystals allows for reducing the scintillator cost per unit volume and increasing the sensitivity along with the energy and timing resolution of the detector. In addition, on thick detectors the depth-of-interaction can be determined without additional hardware. However, costly and complex calibration procedures have been proposed to achieve optimal detector performance for monolithic detectors. This hampers their use in commercial systems. There is thus, a need for simple calibration routines that can be performed on assembled systems. The main goal of this work is to develop a simplified calibration procedure based on acquired training data. In comparison with other methods that use training data acquired with beam sources attached to robotic stages, the proposed method uses a static un-collimated activity source with simple geometry acquiring in a reasonable time. Once the data are acquired, the calibration of the detector is accomplished in three steps: energy calibration based on the k-means clustering method, self-organization based on the self-organizing maps algorithm, and distortion correction based on the Monge-Kantorovich grid adaptation. The proposed calibration method was validated for 2D positioning using a SPECT detector. Similar results were obtained by comparison with an existing calibration method (maximum likelihood estimation). In conclusion, we proposed a novel calibration method for monolithic scintillation detectors that greatly simplifies their use with optimal performance in SPECT systems. PMID:23787300

España, Samuel; Deprez, Karel; Van Holen, Roel; Vandenberghe, Stefaan

2013-07-21

190

Fast calibration of SPECT monolithic scintillation detectors using un-collimated sources  

NASA Astrophysics Data System (ADS)

Monolithic scintillation detectors for positron emission tomography and single-photon emission computed tomography (SPECT) imaging have many advantages over pixelated detectors. The use of monolithic crystals allows for reducing the scintillator cost per unit volume and increasing the sensitivity along with the energy and timing resolution of the detector. In addition, on thick detectors the depth-of-interaction can be determined without additional hardware. However, costly and complex calibration procedures have been proposed to achieve optimal detector performance for monolithic detectors. This hampers their use in commercial systems. There is thus, a need for simple calibration routines that can be performed on assembled systems. The main goal of this work is to develop a simplified calibration procedure based on acquired training data. In comparison with other methods that use training data acquired with beam sources attached to robotic stages, the proposed method uses a static un-collimated activity source with simple geometry acquiring in a reasonable time. Once the data are acquired, the calibration of the detector is accomplished in three steps: energy calibration based on the k-means clustering method, self-organization based on the self-organizing maps algorithm, and distortion correction based on the Monge-Kantorovich grid adaptation. The proposed calibration method was validated for 2D positioning using a SPECT detector. Similar results were obtained by comparison with an existing calibration method (maximum likelihood estimation). In conclusion, we proposed a novel calibration method for monolithic scintillation detectors that greatly simplifies their use with optimal performance in SPECT systems.

España, Samuel; Deprez, Karel; Van Holen, Roel; Vandenberghe, Stefaan

2013-07-01

191

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

192

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

193

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

194

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

195

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

196

Investigation of ZnO-Based Polycrystalline Ceramic Scintillators for Use as ?-Particle Detectors  

SciTech Connect

ZnO-based scintillators are particularly well-suited for use as the associated particle detector in a deuterium-tritium (D-T) neutron generator. Application requirements include the exclusion of organic materials, outstanding timing resolution, and high radiation resistance. ZnO, ZnO:Ga, ZnO:In, ZnO:In,Li, and ZnO:Er,Li have demonstrated fast (sub-nanosecond) decay times with relatively low light yields. ZnO:Ga has been used in a powder form as the associated particle detector for a D-T neutron generator. Unfortunately, detectors using powders are difficult to assemble and the light yield from powders is less than satisfactory. Single crystal ZnO of sufficient size has only recently become available. New applications for D-T neutron generators require better timing resolution and higher count rates than are currently available with associated particle detectors using YAP:Ce as the scintillator. Recent work suggests that ZnO-based scintillators can provide alpha-particle-excited light yields comparable to YAP:Ce scintillators. ZnO-based polycrystalline ceramic scintillators offer the advantages of high light yield, ease of fabrication, low cost, and robust mechanical properties. Precursor powders used in these studies include ZnO and ZnO:Ga powders synthesized using solution phase, urea precipitation, and combustion synthesis techniques as well as ZnO powder from a commercial vendor. Precursor powders have been sintered using uniaxial hot pressing and spark plasma sintering techniques. Photoluminescence measurements have confirmed that, for most samples, the emissions from these sintered bodies consist primarily of slow, visible emissions rather than the desired, sub-nanosecond near-band-edge emissions. Subsequent hydrogen treatments have shown significant improvements in the luminescence characteristics of some ceramic bodies while other samples have shown no change in luminescence.

Neal, John S [ORNL; DeVito, David M [ORNL; Armstrong, Beth L [ORNL; Hong, Mei [University of California; Kesanli, Banu [ORNL; Yang, Xiaocheng [West Virginia University; Giles, N. C. [West Virginia University; Howe, Jane Y [ORNL; Ramey, Joanne Oxendine [ORNL; Wisniewski, Dariusz J [ORNL; Wisniewski, Monica [Oak Ridge National Laboratory (ORNL); Munir, Zuhair [University of California; Boatner, Lynn A [ORNL

2009-01-01

197

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 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 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 SrI2(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

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); Magyar, Albert [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 [Radiation Monitoring Devices, Watertown, MA

2010-01-01

198

New profiled silicon PIN photodiode for scintillation detector  

SciTech Connect

Silicon photodiodes (planar PIN) are employed for the read out of scintillation shower counters. The authors have already reported on a new doping method called molecular layer doping (MLD) which has been developed for very large scale integrated (VLSI) technologies. In tis study, several types of PIN photodiodes, in which a p{sup +} layer was formed by MLD (MLD-PIN) or BFD{sub 2} ion implantation (BF{sub 2} I/I-PIN), have been examined. The MLD-PIN has a shallow P{sup +} junction depth (x{sub j}) with sufficient high surface concentration, and simply and easily provides good performance for a short-wavelength photo sensitivity.

Saitoh, Y.; Akamine, T.; Satoh, K.; Inoue, M.; Yamanaka, J.; Aoki, K.; Miyahara, S.; Kamiya, M.; Ikeda, H.; Avrillon, S.; Okuno, S.

1995-08-01

199

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

200

Double ? experiments with the help of scintillation and HPGe detectors at Gran Sasso  

NASA Astrophysics Data System (ADS)

A search for double beta decay of 64,70Zn, 180,186W was carried out by using low background ZnWO4 crystal scintillators, while a CeCl3 scintillation detector was applied to investigate 2? processes in 136,138,142Ce. A search for 2? decay of 96,104Ru, 156,158Dy, 190,198Pt and study of 2?2? decay of 100Mo to the first excited 0+ level of 100Ru were realized by ultra-low background HPGe ? spectrometry. Moreover, CdWO4 crystal scintillators from enriched 106Cd and 116Cd isotopes were developed to search for 2? decay of 106Cd and 116Cd. Finally, experiments aimed to investigate 96,104Ru and 116Cd are in progress and a new phase of the experiment to search for 2? processes in 106Cd is in preparation.

Barabash, A.; Belli, P.; Bernabei, R.; Boiko, R. S.; Brudanin, V. B.; Cappella, F.; Caracciolo, V.; Cerulli, R.; Chernyak, D. M.; Danevich, F. A.; D'Angelo, S.; di Marco, A.; di Vacri, M. L.; Dossovitskiyj, A. E.; Galashov, E. N.; Grinyov, B. V.; Incicchitti, A.; Kobychev, V. V.; Konovalov, S. I.; Kovtun, G. P.; Kropivyansky, B. N.; Kudovbenko, V. M.; Laubenstein, M.; Mikhlin, A. L.; Nagornaya, L. L.; Nagorny, S. S.; Nagornyi, P. G.; Nisi, S.; Poda, D. V.; Podviyanuk, R. B.; Prosperi, D.; Polischuk, O. G.; Shcherban, A. P.; Shlegel, V. N.; Solopikhin, D. A.; Stenin, Y. G.; Suhonen, J.; Tolmachev, A. V.; Tretyak, V. I.; Umatov, V. I.; Vasiliev, Y. V.; Virich, V. D.; Vyshnevskyi, I. M.; Yavetskiy, R. P.; Yurchenko, S. S.

2011-12-01

201

Development of a Gamma-ray Burst Detector Based on the Silicon Drift Detector Array and Scintillators  

SciTech Connect

We propose a gamma-ray burst (GRB) detector combining the silicon drift detector (SDD) array and scintillators with broadband X-ray and gamma-ray coverage (0.5-1000 keV or more), high energy resolution (2-10%) and high time resolution ({approx}{mu}s) in space. To realize such compact high-performance detector without photomultiplier tubes, we constructed proto-type model using KETEK SDD with a detection area of 1 cm{sup 2} and BGO crystal. The detector shows a very good performance. Obtained FWHM energy resolution was 191 eV at 5.9 keV in the SDD, while 6.5 % at 662 keV in the BGO at -30 deg. C. Evaluation of the 7 channel SDD array and development of analog ASIC for its readout are also presented.

Yamaoka, Kazutaka; Arai, Yusuke; Doshida, Takaaki; Watanabe, Tsuyoshi; Tsutsui, Akihito; Asano, Satoshi; Yoshida, Kotaro; Yoshida, Atsumasa [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 229-8558 (Japan); Pahlke, Andreas [KETEK GmbH, Hofer Strasse 3, 81737 Munchen (Germany); Ikeda, Hirokazu; Takahashi, Tadayuki [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS/JAXA), 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Mori, Kunishiro [Clear Pulse Ltd, 6-25-17 Chuoh, Ohta-ku, Tokyo 143-0024 (Japan); Kato, Hiroshi [Makishima Cosmic Radiation Laboratory, Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

2008-05-22

202

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

203

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

2012-01-01

204

Reflection properties of scintillator-septum candidates for a pixelated MeV detector  

NASA Astrophysics Data System (ADS)

In order to predict and improve the performance of pixelated detectors, it is important to understand the optical properties of the basic unit of the scintillating structure in the detector. To measure one of the essential optical properties, reflectance, we have used a device composed of a laser and photodiode array. We have also developed an analytical model of the optical phenomena based on Snell's law and the Fresnel equations to simply analyze measured results and reflectance parameters at the interface. The computed and experimentally measured results typically have good agreement, validating the analytical model and measurements. The optical parameters are used as inputs to GEANT4 [1]. The simulations are then leveraged to optimize an imager design before a prototype is built. The optical reflectance was measured by using relatively inexpensive samples. A sample has scintillator, glue, and septum (reflector) layers, and each sample has a different scintillator surface (polished/rough) and/or reflector [ESR film/aluminum-sputtered (coated) ESR film] condition. A high-refractive-index hemisphere was attached on the top surface of a sample to increase the maximum incidence angle at the scintillator-glue interface from 27° to 52°. The sample including ESR film demonstrated average reflectance approximately 1.3 times higher than that from the sample with aluminum-sputtered ESR film as a reflector, and the polished surface condition showed higher reflectance than the rough-cut surface condition.

Shin, Mihye; Star-Lack, Josh; Janecek, Martin; Abel, Eric; Shedlock, Daniel; Fahrig, Rebecca

2014-03-01

205

Prototype for SONTRAC: a scintillating plastic fiber detector for solar neutron spectroscopy  

NASA Astrophysics Data System (ADS)

We report the scientific motivation for and performance measurements of a prototype detector system for SONTRAC, a solar neutron tracking experiment designed to study high- energy solar flare processes. The full SONTRAC instrument will measure the energy and direction of 20 to 200 MeV neutrons by imaging the ionization tracks of the recoil protons in a densely packed bundle of scintillating plastic fibers. The prototype detector consists of a 12.7 mm square bundle of 250 micrometer scintillating plastic fibers, 10 cm long. A photomultiplier detects scintillation light from one end of the fiber bundle and provides a detection trigger to an image intensifier/CCD camera system at the opposite end. The image of the scintillation light is recorded. By tracking the recoil protons from individual neutrons the kinematics of the scattering are determined, providing a high signal to noise measurement. The predicted energy resolution is 10% at 20 MeV, improving with energy. This energy resolution translates into an uncertainty in the production time of the neutron at the Sun of 30 s for a 20 MeV neutron, also improving with energy. A SONTRAC instrument will also be capable of detecting and measuring high-energy gamma rays greater than 20 MeV as a 'solid-state spark chamber.' The self-triggering and track imaging features of the prototype are demonstrated with cosmic ray muons and 14 MeV neutrons. Design considerations for a space flight instrument are presented.

Ryan, James M.; Baltgalvis, Janis; Holslin, Daniel T.; Macri, John R.; McConnell, Mark L.; Polichar, Aaron R.; Wunderer, Cornelia B.

1997-10-01

206

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)] [Forschungszentrum Juelich GmbH (Germany); Jansen, E.; Schaefer, W. [Univ. Bonn (Germany). Mineralogisches Inst.] [Univ. Bonn (Germany). Mineralogisches Inst.

1998-06-01

207

Scintillating-fiber imaging detector for 14-MeV neutrons  

SciTech Connect

The authors have created a detector to image the neutrons emitted by imploded inertial-confinement fusion targets. The 14-MeV neutrons, which are produced by deuterium-tritium fusion events in the target, pass through an aperture to create an image on the detector. The neutron radiation is converted to blue light (430 nm) with a 20-cm-square array of plastic scintillating fibers. Each fiber is 10-cm long with a 1-mm-square cross section; approximately 35-thousand fibers make up the array. The resulting blue-light image is reduced and amplified by a sequence of fiber-optic tapers and image intensifiers, then acquired by a CCD camera. The fiber-optic readout system was tested optically for overall throughput the resolution. The authors plan to characterize the scintillator array reusing an ion-beam neutron source as well as DT-fusion neutrons emitted by inertial confinement targets. Characterization experiments will measure the light-production efficiency, spatial resolution, and neutron scattering within the detector. Several neutron images of laser-fusion targets have been obtained with the detector. Several neutron images of laser-fusion targets have been obtained with the detector. They describe the detector and their characterization methods, present characterization results, and give examples of the neutron images.

Ress, D.; Lerche, R.A.; Ellis, R.J.; Heaton, G.W.; Nelson, M.B.; Mant, G. [Lawrence Livermore National Lab., CA (United States); Lehr, D.E. [Stanford Univ., CA (United States). Physics Dept.

1994-07-25

208

Measurements of /(n,?) neutron capture cross-sections with liquid scintillator detectors  

NASA Astrophysics Data System (ADS)

A method for measuring (n,?) neutron capture cross-sections using liquid scintillator detectors has been investigated. If the response function of the detector is known, and the efficiency as a function of energy is low and approximately constant, then gamma cascades can be counted via a method that is independent of the cascade path provided the detector response is manipulated to allow detection efficiency to be proportional to emitted gamma-ray energy. In this paper, we demonstrate the measurement of efficiency and response functions for a C 6D 6 liquid scintillator using gamma-ray sources and (p,?) reactions on light nuclei. Methods to reproduce the detector response and efficiency data successfully using simulations are presented and discussed. An entire response matrix for the detector has been constructed using a new interpolation technique, allowing weighting functions that force the detector efficiency to be proportional to gamma-ray energy to be calculated. An analysis of the sources of error involved in making (n,?) cross-section measurements with this method has been undertaken using Monte-Carlo simulation techniques.

Wilson, J. N.; Haas, B.; Boyer, S.; Dassie, D.; Barreau, G.; Aiche, M.; Czajkowski, S.; Grosjean, C.; Guiral, A.

2003-10-01

209

A large-scale low-background liquid scintillation detector: the counting test facility at Gran Sasso  

NASA Astrophysics Data System (ADS)

A 4.8 m3 unsegmented liquid scintillation detector at the underground Laboratori Nazionali del Gran Sasso has shown the feasibility of multi-ton low-background detectors operating to energies as low as 250 keV. Detector construction and the handling of large volumes of liquid scintillator to minimize the background are described. The scintillator, 1.5 g PPO/L-pseudocumene, is held in a flexible nylon vessel shielded by 1000 t of purified water. The active detector volume is viewed by 100 photomultipliers, which measure time and charge for each event, from which energy, position and pulse shape are deduced. On-line purification of the scintillator by water extraction, vacuum distillation and nitrogen stripping removed radioactive impurities. Upper limits were established of < 10-7 Bq/kg-scintillator for events with energies 250 keV < E < 800 keV, and < 10-9 Bq/kg-scintillator due to the decay products of uranium and thorium. The isotopic abundance of 14C/12C in the scintillator was shown to be approximately 10-18 by extending the energy window of the detector to 25-250 keV. The 14C abundance and uranium and thorium levels in the CTF are compatible with the Borexino Solar Neutrino Experiment.

Alimonti, G.; Arpesella, C.; Bacchiocchi, G.; Balata, M.; Bellini, G.; Benziger, J.; Bonetti, S.; Brigatti, A.; Cadonati, L.; Calaprice, F. P.; Cavaletti, R.; Cecchet, G.; Chen, M.; Darnton, N.; Debari, A.; Deutsch, M.; Elisei, F.; von Feilitzsch, F.; Galbiati, C.; Garagiola, A.; Gatti, F.; Giammarchi, M. G.; Giugni, D.; Goldbrunner, T.; Golubchikov, A.; Goretti, A.; Grabar, S.; Hagner, T.; Hartmann, F.; von Hentig, R.; Heusser, G.; Ianni, A.; Jochum, J.; Johnson, M.; Laubenstein, M.; Loeser, F.; Lombardi, P.; Magni, S.; Malvezzi, S.; Manno, I.; Manuzio, G.; Masetti, F.; Mazzucato, U.; Meroni, E.; Neff, M.; Nisi, S.; Nostro, A.; Oberauer, L.; Perotti, A.; Preda, A.; Raghavan, P.; Raghavan, R. S.; Ranucci, G.; Resconi, E.; Ruscitti, P.; Scardaoni, R.; Schoenert, S.; Smirnov, O.; Tartaglia, R.; Testera, G.; Ullucci, P.; Vogelaar, R. B.; Vitale, S.; Zaimidoroga, O.

1998-02-01

210

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

211

The empirical characterization of organic liquid scintillation detectors by the normalized average of digitized pulse shapes  

NASA Astrophysics Data System (ADS)

The application of the digital acquisition of pulses from a liquid scintillator to detector characterization is described. Experimental data for a mixed neutron/ ?-ray field have been recorded digitally. An empirical method for the characterization of liquid scintillation detectors, in terms of their pulse shape, has been developed which is quick and easy. It provides generic pulses shapes for use in pulse-shape discrimination and that can be used to derive analytical descriptions of each pulse via an accepted six-parameter formulism. The distributions of the neutron and ?-ray components arising as a result of discrimination via pulse gradient analysis (PGA) follow a bi-Gaussian trend and exhibit degrees of both kurtosis and skew.

Aspinall, M. D.; D'Mellow, B.; Mackin, R. O.; Joyce, M. J.; Jarrah, Z.; Peyton, A. J.

2007-07-01

212

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

213

Advances in Inorganic Scintillation Detectors for Geophysical Applications  

SciTech Connect

The ability to distinguish between geological formations and the change from one formation to another is crucial to the oil exploration and well logging industry. These changes are distinguished by the use of gamma-ray measurements, which detect the radioactive isotope combinations of potassium, thorium, and uranium present in the rock and fluid of these geological formations. A gamma radiation detector consisting of a sodium iodide crystal optically coupled to a photomultiplier tube is used for making these measurements. Because of the harsh environment seen while down hole, these detectors must be rugged in order to survive and perform under the conditions of extreme temperature, shock, and vibration. The two main geophysical applications designed for are wireline and measurement-while-drilling (MWD) environments. Three major product designs that fall under these environmental survival and performance criteria are discussed.

Julie L. Champlin; Carlos M. Grodsinsky; William D. Sekela

1998-12-31

214

Imaging detectors based on the gas electron multiplier scintillation light  

Microsoft Academic Search

We have developed a novel type of two-dimensional, large area, low granularity gaseous position sensitive detector using a gas electron multiplier foil (GEM) and a standard CCD camera with glass optics. First results obtained with a 10×10 cm2 GEM foil demonstrate that the position resolution with 7 keV X-rays using a Xe-CO2 mixture is better than 100 ?m (RMS). The

F. A. F. Fraga; S. T. G. Fetal; L. M. S. Margato; I. Ivaniouchenkov; R. F. Marques; A. J. P. L. Policarpo

1999-01-01

215

Evemt Localization in a Continuous Scintillation Detector Using Digital Processing  

Microsoft Academic Search

We have designed, constructed and begun to evaluate a two-dimensional position-sensitive detector which will be used in a multi-slice PET scanner. We have measured 5.2 mm transverse and 6.0 mm axial spatial resolution, with an array of thirty 5-cm PMTs (10-columns by 3 rows). The pulses are shortened and integrated for 240 nsec, which results in a countrate capability of

Joel S. Karp; Gerd Muehllehner; Daniel Beerbohm; David Mankoff

1986-01-01

216

Methods to extract more light from minute scintillation crystals used in an ultra-high resolution positron emission tomography detector  

Microsoft Academic Search

Recently, there has been great interest in developing finely pixellated position-sensitive scintillation detectors for ultra-high-resolution Positron Emission Tomography (PET) systems designed for breast cancer detection, diagnosis, and staging and for imaging small laboratory animals. We are developing a different high-resolution PET detector design that promotes nearly complete scintillation light collection in ?1mm wide, >10mm thick lutetium oxyorthosilicate (LSO) crystals. The

Craig S Levin; Frezghi Habte; Angela M Foudray

2004-01-01

217

Methods to extract more light from minute scintillation crystals used in an ultra-high resolution positron emission tomography detector  

Microsoft Academic Search

Recently, there has been great interest in developing finely pixellated position-sensitive scintillation detectors for ultra-high-resolution Positron Emission Tomography (PET) systems designed for breast cancer detection, diagnosis, and staging and for imaging small laboratory animals. We are developing a different high-resolution PET detector design that promotes nearly complete scintillation light collection in 10mm thick lutetium oxyorthosilicate (LSO) crystals. The design requires

Craig S. Levin; Frezghi Habte; Angela M. Foudray

2004-01-01

218

Limits on WIMP dark matter using scintillating CaWO 4 cryogenic detectors with active background suppression  

Microsoft Academic Search

We present first significant limits on WIMP dark matter by the phonon-light technique, where combined phonon and light signals from a scintillating cryogenic detector are used. Data from early 2004 with two 300g CRESST-II prototype detector modules are presented, with a net exposure of 20.5kg days. The modules consist of a CaWO4 scintillating “target” crystal and a smaller cryogenic light

G. Angloher; C. Bucci; P. Christ; C. Cozzini; F. von Feilitzsch; D. Hauff; S. Henry; Th. Jagemann; J. Jochum; H. Kraus; B. Majorovits; J. Ninkovic; F. Petricca; W. Potzel; F. Probst; Y. Ramachers; M. Razeti; W. Rau; W. Seidel; M. Stark; L. Stodolsky; A. J. B. Tolhurst; W. Westphal; H. Wulandari

2005-01-01

219

X-Ray Image Detector Based on Light Guides and Scintillators  

Microsoft Academic Search

This paper reports on a study concerning the design of an X-ray detector that is suitable to analyze a small area with high spatial resolution. The indirect method of X-ray detection is used, i.e., the X-rays are first converted into visible light, which is then detected. In this design, an array of CsI:Tl scintillators, encapsulated by aluminum walls, is coupled

J. G. Rocha; R. A. Dias; L. Goncalves; G. Minas; A. Ferreira; C. M. Costa; S. Lanceros-Mendez

2009-01-01

220

The 1000ton liquid scintillation detector project at Kamioka (Kam-LAND)  

SciTech Connect

We are constructing 1,000ton liquid scintillation detector at the old Kamiokande cave in order to detect low energy (anti)neutrinos from various sources. The main physics target of this experiment is to measure the neutrino oscillation parameter; {delta}m{sup 2} down to 10{sup -5} eV{sup 2} by detecting reactor antineutrinos coming from 150 to 200 km away. An outline of this experiment is explained in this paper.

Suekane, F. [Faculty of Science, Tohoku University, Sendai, 980-77 (Japan)

1997-05-20

221

Gamma-Ray Spectroscopy With LaBr :Ce Scintillator Readout by a Silicon Drift Detector  

Microsoft Academic Search

In this paper, the authors propose a gamma-ray spectrometer based on a LaBr3 :Ce scintillator coupled to a silicon drift detector (SDD). The SDD is a photodetector characterized by a very low noise thanks to the low value of output capacitance independent from the active area. With respect to a PMT, the SDD offers a higher quantum efficiency which reduces

C. Fiorini; A. Gola; M. Zanchi; A. Longoni; P. Lechner; H. Soltau; L. Struder

2006-01-01

222

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

223

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

224

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

2012-06-01

225

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

226

Performance results for scintillation detectors for high temperature environments including MWD  

SciTech Connect

Sheet reflectors and elastomeric potting materials have become available for packaging NaI(T1) scintillation detectors. As a mechanical element of the system, these materials offer substantial advantages over the more traditional packed powders. In oil well applications, compatibility of the materials with NaI(T1) at high temperature presents a challenge. Specially treated systems are compatible with NaI(T1) to at least 200/sup 0/C. Performance for new, unstabilized detectors is the same as powder systems with only a 5 to 10% pulse height drop during initial exposure to 180/sup 0/C. Additional data to 200/sup 0/C shows similar stable results.

Dayton, R.; Mayhugh, M.; Papp, M.; Parkhurst, P.; Schreiner, R.

1988-02-01

227

A New scintillator tile / fiber preshower detector for the CDF central calorimeter  

SciTech Connect

A detector designed to measure early particle showers has been installed in front of the central CDF calorimeter at the Tevatron. This new preshower detector is based on scintillator tiles coupled to wavelength-shifting fibers read out by multianode photomultipliers and has a total of 3,072 readout channels. The replacement of the old gas detector was required due to an expected increase in instantaneous luminosity of the Tevatron collider in the next few years. Calorimeter coverage, jet energy resolution, and electron and photon identification are among the expected improvements. The final detector design, together with the R&D studies that led to the choice of scintillator and fiber, mechanical assembly, and quality control are presented. The detector was installed in the fall 2004 Tevatron shutdown and is expected to start collecting colliding beam data by the end of 2004. First measurements indicate a light yield of 12 photoelectrons/MIP, a more than two-fold increase over the design goals.

Gallinaro, Michele; /Rockefeller U.; Artikov, A.; Bromberg, C.; Budagov, J.; Byrum, K.; Chang, S.; Chlachidze, G.; Goulianos, K.; Huston, J.; Iori, M.; Kim, M.; Kuhlmann, S.; Lami, S.; Lindgren, M.; Lytken, E.; Miller, R.; Nodulman, L.; Pauletta, G.; Penzo, A.; Proudfoot, J.; Roser, R.; /Argonne /Dubna, JINR /Fermilab /Kyungpook Natl. U. /Michigan State U. /INFN, Siena /Rockefeller U. /INFN, Rome /INFN, Trieste /INFN, Udine /Tsukuba U.

2004-11-01

228

High resolution positron emission tomography with a prototype camera based on solid state scintillation detectors  

SciTech Connect

The prototype of a high resolution PET camera consisting of two opposite arrays of detectors with independent solid state readout was built and tested. The basic detector unit is the RCA C30994 detector module consisting of two 3 {times} 5 {times} 20 mm BGO scintillators, each coupled to one silicon avalanche photodiode. The two-dimensional stacking capability of the module allows a high resolution multi-ring detection system to be assembled without crystal coding. This paper reports on the prototype used to simulate a 31 cm diameter dual ring tomograph suitable for animal studies. Coincident detector pair resolution was measured and the contributions to resolution loss estimated using a platinum sheathed .75 mm {sup 68}Ge line source.

Lecomte, R.; Cadorette, J.; Jouan, A.; Heon, M.; Rouleau, D.; Gauthier, G. (Dept. of Nuclear Medicine and Radiobiology, Univ. of Sherbrooke, Sherbrooke, Quebec J1H 5N4 (CA))

1990-04-01

229

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

230

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

SciTech Connect

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 {approximately}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. [Univ. of California, Berkeley, CA (United States). Dept. of Engineering-Nuclear Engineering]|[Lawrence Berkeley Lab., CA (United States). Physics Div.

1995-05-01

231

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

232

Setup for irradiation and characterization of materials and Si particle detectors at cryogenic temperatures  

Microsoft Academic Search

A novel facility for proton irradiation with sample cryocooling has been developed at the Accelerator Laboratory of Helsinki University (equipped with a 5MV tandem accelerator). The setup enables unique experiments to be carried out within the temperature range of 10–300K. The setup has been constructed for “on-line” studies of vacancies with positron annihilation spectroscopy (PAS) including the option for optical

S. Väyrynen; P. Pusa; P. Sane; P. Tikkanen; J. Räisänen; K. Kuitunen; F. Tuomisto; J. Härkönen; I. Kassamakov; E. Tuominen; E. Tuovinen

2007-01-01

233

Temperature sensitivity of a Bonner-sphere LiI(Eu) scintillation neutron detector  

SciTech Connect

Neutron spectroscopy with Bonner spheres involves a sequence of measurements with a LiI(Eu) scintillation detector with several moderating spheres. The measured quantity is the count rate of the {sup 6}Li(n,{alpha}){sup 3}H reaction, using either a net or gross integral over a preset limited range of the pulse-height distribution to discriminate against the ever-present gamma radiation in neutron environments. Unfolding codes utilize these count rates to produce neutron fluence spectra. The accuracy of the measured count rate depends, among other things, on the overall stability of the detector and electronics system. Elevated temperatures may alter count rates measured with scintillation radiation detectors because of increased thermoionic emission of the cathode and dynodes at higher temperatures. Field measurements with Bonner spheres in operating nuclear power reactor containment buildings often encounter temperatures as high as 50 C ({approximately}120 F). Hence, the effect of higher temperatures on the {sup 6}LiI(Eu) crystal and photomultiplier tube of the Bonner sphere has been investigated and documented. The nominal temperature sensitivity of the 4-mm LiI(Eu) detector is {approximately}0.12%/{degree}C between 25 and 50 C. On an absolute scale, the difference in count rate within a 25C range translates to an {approximately}4% error, according to the measurements presented.

West, L.; Lemley, E.C. (Univ. of Arkansas, Fayetteville (United States))

1992-01-01

234

An experimental study of antireflective coatings in Ge light detectors for scintillating bolometers  

NASA Astrophysics Data System (ADS)

Luminescent bolometers are double-readout devices able to measure simultaneously the phonon and the light yields after a particle interaction in the detector. This operation allows in some cases to tag the type of the interacting quantum, crucial issue for background control in rare event experiments such as the search for neutrinoless double beta decay and for interactions of particle dark matter candidates. The light detectors used in the LUCIFER and LUMINEU searches (projects aiming at the study of the double beta interesting candidates 82Se and 100Mo using ZnSe and ZnMoO4 scintillating bolometers) consist of hyper-pure Ge thin slabs equipped with NTD thermistors. A substantial sensitivity improvement of the Ge light detectors can be obtained applying a proper anti-reflective coatings on the Ge side exposed to the luminescent bolometer. The present paper deals with the investigation of this aspect, proving and quantifying the positive effect of a SiO2 and a SiO coating and setting the experimental bases for future tests of other coating materials. The results confirm that an appropriate coating procedure helps in improving the sensitivity of bolometric light detectors by an important factor (in the range 20% - 35%) and needs to be included in the recipe for the development of an optimized radio-pure scintillating bolometer.

Mancuso, M.; Beeman, J. W.; Giuliani, A.; Dumoulin, L.; Olivieri, E.; Pessina, G.; Plantevin, O.; Rusconi, C.; Tenconi, M.

2014-01-01

235

Simulation of the Scintillator Geometry in the Electromagnetic Calorimeter in the CLAS12 Detector  

NASA Astrophysics Data System (ADS)

We have modified the geometry of the electromagnetic calorimeter (EC) in a simulation of the CLAS12 detector at Jefferson Lab (JLab). The goal of JLab is to understand how quarks and gluons form nucleons and nuclei. It is being upgraded with a higher energy beam and new detectors including CLAS12 in Hall B. To prepare for CLAS12's operation, we use the code gemc that is based on Geant4 to simulate particle tracks. The EC is one of the CLAS12 components and it is used to measure the energy and position of charged and neutral particles. It is composed of alternating layers of lead and scintillating plastic. Each layer of scintillator is, in turn, composed of 36 parallel strips that form a triangle about 4.7 m on a side. Adjacent layers are rotated 120 degrees so the crossed strips can be used to determine the position of a hit. In the past the scintillators have been defined as a large slab instead of stips to reduce computation time. We have redefined them as the more realistic strips in gemc. Using the UNIX ``time'' command we observe about a 5% increase in CPU time in the EC simulation. To test the effect on the interactive graphics in gemc we use glxgears and see about a 25% decrease in frame rate.

Sherman, Keegan; Gilfoyle, Gerard

2012-10-01

236

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

NASA Astrophysics Data System (ADS)

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 d E/d x measurements - fully stripped nuclei of cosmic origin in the experiment CALET. The latter is a space mission by the Japanese Space Agency (JAXA) scheduled to be launched to the International Space Station (ISS) in 2013. The CALET instrument is managed by an international collaboration and it is scheduled to take data for 5 years on the Exposure Facility (JEM-EF) of the Japanese module KIBO on the ISS. The aim of the test was to accurately measure the response of the scintillator to different nuclear species and parametrize the saturation of the scintillation light in order to assess the impact of this effect on the charge resolution of the instrument.

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

2011-12-01

237

Can scintillation detectors with low spectral resolution accurately determine radionuclides content of building materials?  

PubMed

The current paper makes an attempt to check whether the scintillation NaI(Tl) detectors, in spite of their poor energy resolution, can determine accurately the content of NORM in building materials. The activity concentrations of natural radionuclides were measured using two types of detectors: (a) NaI(Tl) spectrometer equipped with the special software based on the matrix method of least squares, and (b) high-purity germanium spectrometer. Synthetic compositions with activity concentrations varying in a wide range, from 1/5 to 5 times median activity concentrations of the natural radionuclides available in the earth crust and the samples of popular building materials, such as concrete, pumice and gypsum, were tested, while the density of the tested samples changed in a wide range (from 860 up to 2,410 kg/m(3)). The results obtained in the NaI(Tl) system were similar to those obtained with the HPGe spectrometer, mostly within the uncertainty range. This comparison shows that scintillation spectrometers equipped with a special software aimed to compensate for the lower spectral resolution of NaI(Tl) detectors can be successfully used for the radiation control of mass construction products. PMID:23542118

Kovler, K; Prilutskiy, Z; Antropov, S; Antropova, N; Bozhko, V; Alfassi, Z B; Lavi, N

2013-07-01

238

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

239

A Unique TAS Setup for high multiplicity events at VECC, Kolkata using BaF2 detectors  

NASA Astrophysics Data System (ADS)

A granular total absorption spectrometer (TAS) has been developed at the Variable Energy Cyclotron Centre, Kolkata, India using 50 elements of BaF2 detectors and covering 4?. The advantage with such a granular setup is that one can get sum spectrum with the condition of different multiplicity hits in an event. It has been shown that one can get clean sum-peaks devoid of individual peaks with the choice of two or higher fold of multiplicity. The large granularity makes it a unique TAS setup particularly for the high multiplicity events. The set up has been tested using different radioactive sources with one, two or multiple ? rays in cascade. The set up is ready to be used online.

Mukherjee, G.; Dey, Balaram; Mukhopadhyay, S.; Pandit, Deepak; Pal, Surajit; Pai, H.; Banerjee, S. R.

2014-03-01

240

Monte Carlo code G3sim for simulation of plastic scintillator detectors with wavelength shifter fiber readout.  

PubMed

A detailed description of a compact Monte Carlo simulation code "G3sim" for studying the performance of a plastic scintillator detector with wavelength shifter (WLS) fiber readout is presented. G3sim was developed for optimizing the design of new scintillator detectors used in the GRAPES-3 extensive air shower experiment. Propagation of the blue photons produced by the passage of relativistic charged particles in the scintillator is treated by incorporating the absorption, total internal, and diffuse reflections. Capture of blue photons by the WLS fibers and subsequent re-emission of longer wavelength green photons is appropriately treated. The trapping and propagation of green photons inside the WLS fiber is treated using the laws of optics for meridional and skew rays. Propagation time of each photon is taken into account for the generation of the electrical signal at the photomultiplier. A comparison of the results from G3sim with the performance of a prototype scintillator detector showed an excellent agreement between the simulated and measured properties. The simulation results can be parametrized in terms of exponential functions providing a deeper insight into the functioning of these versatile detectors. G3sim can be used to aid the design and optimize the performance of scintillator detectors prior to actual fabrication that may result in a considerable saving of time, labor, and money spent. PMID:22559526

Mohanty, P K; Dugad, S R; Gupta, S K

2012-04-01

241

Monte Carlo code G3sim for simulation of plastic scintillator detectors with wavelength shifter fiber readout  

SciTech Connect

A detailed description of a compact Monte Carlo simulation code ''G3sim'' for studying the performance of a plastic scintillator detector with wavelength shifter (WLS) fiber readout is presented. G3sim was developed for optimizing the design of new scintillator detectors used in the GRAPES-3 extensive air shower experiment. Propagation of the blue photons produced by the passage of relativistic charged particles in the scintillator is treated by incorporating the absorption, total internal, and diffuse reflections. Capture of blue photons by the WLS fibers and subsequent re-emission of longer wavelength green photons is appropriately treated. The trapping and propagation of green photons inside the WLS fiber is treated using the laws of optics for meridional and skew rays. Propagation time of each photon is taken into account for the generation of the electrical signal at the photomultiplier. A comparison of the results from G3sim with the performance of a prototype scintillator detector showed an excellent agreement between the simulated and measured properties. The simulation results can be parametrized in terms of exponential functions providing a deeper insight into the functioning of these versatile detectors. G3sim can be used to aid the design and optimize the performance of scintillator detectors prior to actual fabrication that may result in a considerable saving of time, labor, and money spent.

Mohanty, P. K.; Dugad, S. R.; Gupta, S. K. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005 (India)

2012-04-15

242

Monte Carlo code G3sim for simulation of plastic scintillator detectors with wavelength shifter fiber readout  

NASA Astrophysics Data System (ADS)

A detailed description of a compact Monte Carlo simulation code ``G3sim'' for studying the performance of a plastic scintillator detector with wavelength shifter (WLS) fiber readout is presented. G3sim was developed for optimizing the design of new scintillator detectors used in the GRAPES-3 extensive air shower experiment. Propagation of the blue photons produced by the passage of relativistic charged particles in the scintillator is treated by incorporating the absorption, total internal, and diffuse reflections. Capture of blue photons by the WLS fibers and subsequent re-emission of longer wavelength green photons is appropriately treated. The trapping and propagation of green photons inside the WLS fiber is treated using the laws of optics for meridional and skew rays. Propagation time of each photon is taken into account for the generation of the electrical signal at the photomultiplier. A comparison of the results from G3sim with the performance of a prototype scintillator detector showed an excellent agreement between the simulated and measured properties. The simulation results can be parametrized in terms of exponential functions providing a deeper insight into the functioning of these versatile detectors. G3sim can be used to aid the design and optimize the performance of scintillator detectors prior to actual fabrication that may result in a considerable saving of time, labor, and money spent.

Mohanty, P. K.; Dugad, S. R.; Gupta, S. K.

2012-04-01

243

ACE-CRIS Scintillating Optical Fiber Trajectory (SOFT) detector: a calibration at the NSCL  

NASA Astrophysics Data System (ADS)

The scintillating optical fiber trajectory (SOFT) detector, which is the hodoscope for the cosmic ray isotope spectrometer (CRIS) on the NASA advanced composition explorer (ACE) satellite, was calibrated using 155 MeV/n He, Li, C, N, O, Ne, and Ar at the Michigan State University National Superconducting Cyclotron Laboratory (NSCL). The instrument consists of three hodoscope fiber planes and one trigger plane which are read out by an image intensified CCD camera system and by intensified photodiodes respectively. The instrument is described and the detection efficiency and spatial resolution is presented.

Hink, Paul L.; Binns, W. Robert; Klarmann, J.; Olevitch, M. A.

1996-10-01

244

An eight-channel pulse-shape comparator to discriminate signals from fast scintillation detectors  

NASA Astrophysics Data System (ADS)

An eight-channel pulse-shape comparator board is designed to discriminate the signals from fast scintillation detectors. Each channel of the comparator board has guaranteed output with maximum speed of 20 ns. The simple design and low cost per channel make it preferable for use in cosmic rays as well as in extensive air shower (EAS) experiments. A description of the environmental operation and test of the electronics is presented. This device is presently used in an EAS experiment, Gauhati University, Assam, India. We present here, details about the hardware aspect of the electronics. Results of the comparator electronics are also presented.

Bezboruah, Tulshi

2001-08-01

245

Data acquisition system for the Large Scintillating Neutrino Detector at Los Alamos  

SciTech Connect

The data acquisition system for the Large Scintillating Neutrino Detector (LSND) is described. The system collects time and charge information in real time from 1600 photomultiplier tubes and passes the data in intelligent-trigger selected time windows to analysis computers, where events are reconstructed and analyzed as candidates for a variety of neutrino-related physics processes. The system is composed of fourteen VME crates linked to a Silicon Graphics, Inc. ``4D/480`` multiprocessor computer through multiple, parallel Ethernets, and a collection of contemporary high-performance workstations.

Anderson, G.; Cohen, I. [Linfield Coll., McMinnville, OR (United States); Homann, B.; Smith, D. [Embry-Riddle Aeronautical Univ., Daytona Beach, FL (United States); Strossman, W.; VanDalen, G.J. [California Univ., Riverside, CA (United States); Weaver, L.S.; Evans, D.; Vernon, W. [California Univ., San Diego, CA (United States); Band, A.; Burman, R.; Chang, T.; Federspiel, F.; Foreman, W.; Gomulka, S.; Hart, G.; Kozlowski, T.; Louis, W.C.; Margulies, J.; Nuanes, A.; Sandberg, V.; Thompson, T.N.; White, D.H.; Whitehouse, D. [Los Alamos National Lab., NM (United States)

1992-10-01

246

Data acquisition system for the Large Scintillating Neutrino Detector at Los Alamos  

SciTech Connect

The data acquisition system for the Large Scintillating Neutrino Detector (LSND) is described. The system collects time and charge information in real time from 1600 photomultiplier tubes and passes the data in intelligent-trigger selected time windows to analysis computers, where events are reconstructed and analyzed as candidates for a variety of neutrino-related physics processes. The system is composed of fourteen VME crates linked to a Silicon Graphics, Inc. 4D/480'' multiprocessor computer through multiple, parallel Ethernets, and a collection of contemporary high-performance workstations.

Anderson, G.; Cohen, I. (Linfield Coll., McMinnville, OR (United States)); Homann, B.; Smith, D. (Embry-Riddle Aeronautical Univ., Daytona Beach, FL (United States)); Strossman, W.; VanDalen, G.J. (California Univ., Riverside, CA (United States)); Weaver, L.S.; Evans, D.; Vernon, W. (California Univ., San Diego, CA (United States)); Band, A.; Burman, R.; Chang, T.; Federspiel, F.; Foreman, W.; Gomulka, S.; H

1992-01-01

247

High resolution X-ray photon-counting detector with scintillator-deposited charge-coupled device  

Microsoft Academic Search

We report on a new photon-counting detector possessing unprecedented spatial resolution and moderate spectral resolution for 0.1-100 keV X-rays. It consists of an X-ray charge-coupled device (CCD) and scintillator. The scintillator is directly coupled to the back surface of the X-ray CCD. Low-energy X-rays below 10 keV can be directly detected by the CCD. The majority of hard X-rays above

Emi Miyata; Noriaki Tawa; Kenji Mukai; Hiroshi Tsunemi; Kazuhisa Miyaguchi

2004-01-01

248

Detector optimization for hand-held CsI(Tl)\\/HgI2 gamma-ray scintillation spectrometer applications  

Microsoft Academic Search

Gamma-ray spectrometers using mercuric iodide (HgI2) photodetectors (PDs) coupled with CsI(Tl) scintillators have shown excellent energy resolutions and high detection efficiency at room temperature. Additionally HgI2 semiconductor PDs allow for extreme miniaturization of the detector packaging compared with photomultiplier tube (PMT) based detectors. These advantages make possible the construction of a new generation of hand-held gamma-ray spectrometers. Studies of detector

Y. J. Wang; B. E. Patt; J. S. Iwanczyk; S. R. Cherry; Y. Shao

1996-01-01

249

Double {beta} experiments with the help of scintillation and HPGe detectors at Gran Sasso  

SciTech Connect

A search for double beta decay of {sup 64,70}Zn, {sup 180,186}W was carried out by using low background ZnWO{sub 4} crystal scintillators, while a CeCl{sub 3} scintillation detector was applied to investigate 2{beta} processes in {sup 136,138,142}Ce. A search for 2{beta} decay of {sup 96,104}Ru, {sup 156,158}Dy, {sup 190,198}Pt and study of 2{nu}2{beta} decay of {sup 100}Mo to the first excited 0{sup +} level of {sup 100}Ru were realized by ultra-low background HPGe {gamma} spectrometry. Moreover, CdWO{sub 4} crystal scintillators from enriched {sup 106}Cd and {sup 116}Cd isotopes were developed to search for 2{beta} decay of {sup 106}Cd and {sup 116}Cd. Finally, experiments aimed to investigate {sup 96,104}Ru and {sup 116}Cd are in progress and a new phase of the experiment to search for 2{beta} processes in {sup 106}Cd is in preparation.

Barabash, A.; Konovalov, S. I.; Umatov, V. I. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Belli, P.; D'Angelo, S.; Di Marco, A. [INFN, Sezione di Roma ''Tor Vergata'', Rome (Italy); Bernabei, R. [INFN, Sezione di Roma ''Tor Vergata '', Rome (Italy); Dipartimento di Fisica, Universita di Roma ''Tor Vergata'', Rome (Italy); Boiko, R. S.; Chernyak, D. M.; Danevich, F. A.; Kobychev, V. V.; Kropivyansky, B. N.; Kudovbenko, V. M.; Nagorny, S. S.; Podviyanuk, R. B.; Polischuk, O. G.; Tretyak, V. I.; Vyshnevskyi, I. M.; Yurchenko, S. S. [Institute for Nuclear Research, Kyiv (Ukraine); Brudanin, V. B. [Joint Institute for Nuclear Research, Dubna (Russian Federation); and others

2011-12-16

250

A novel, SiPM-array-based, monolithic scintillator detector for PET.  

PubMed

Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e.g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as avalanche photodiodes. Here we present a novel detector design with DOI correction, in which a position-sensitive SiPM array is used to read out a monolithic scintillator. Initial characterization of a prototype detector consisting of a 4 x 4 SiPM array coupled to either the front or back surface of a 13.2 mm x 13.2 mm x 10 mm LYSO:Ce(3+) crystal shows that front-side readout results in significantly better performance than conventional back-side readout. Spatial resolutions <1.6 mm full-width-at-half-maximum (FWHM) were measured at the detector centre in response to an approximately 0.54 mm FWHM diameter test beam. Hardly any resolution losses were observed at angles of incidence up to 45 degrees , demonstrating excellent DOI correction. About 14% FWHM energy resolution was obtained. The timing resolution, measured in coincidence with a BaF(2) detector, equals 960 ps FWHM. PMID:19443953

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

2009-06-01

251

A novel, SiPM-array-based, monolithic scintillator detector for PET  

NASA Astrophysics Data System (ADS)

Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e.g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as avalanche photodiodes. Here we present a novel detector design with DOI correction, in which a position-sensitive SiPM array is used to read out a monolithic scintillator. Initial characterization of a prototype detector consisting of a 4 × 4 SiPM array coupled to either the front or back surface of a 13.2 mm × 13.2 mm × 10 mm LYSO:Ce3+ crystal shows that front-side readout results in significantly better performance than conventional back-side readout. Spatial resolutions <1.6 mm full-width-at-half-maximum (FWHM) were measured at the detector centre in response to an ~0.54 mm FWHM diameter test beam. Hardly any resolution losses were observed at angles of incidence up to 45°, demonstrating excellent DOI correction. About 14% FWHM energy resolution was obtained. The timing resolution, measured in coincidence with a BaF2 detector, equals 960 ps FWHM.

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

2009-06-01

252

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

253

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

254

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

255

Neutron energy spectrum measurements with a compact liquid scintillation detector on EAST  

NASA Astrophysics Data System (ADS)

A neutron detector based on EJ301 liquid scintillator has been employed at EAST to measure the neutron energy spectrum for D-D fusion plasma. The detector was carefully characterized in different quasi-monoenergetic neutron fields generated by a 4.5 MV Van de Graaff accelerator. In recent experimental campaigns, due to the low neutron yield at EAST, a new shielding device was designed and located as close as possible to the tokamak to enhance the count rate of the spectrometer. The fluence of neutrons and ?-rays was measured with the liquid neutron spectrometer and was consistent with 3He proportional counter and NaI(Tl) ?-ray spectrometer measurements. Plasma ion temperature values were deduced from the neutron spectrum in discharges with lower hybrid wave injection and ion cyclotron resonance heating. Scattered neutron spectra were simulated by the Monte Carlo transport Code, and they were well verified by the pulse height measurements at low energies.

Yuan, X.; Zhang, X.; Xie, X.; Gorini, G.; Chen, Z.; Peng, X.; Chen, J.; Zhang, G.; Fan, T.; Zhong, G.; Hu, L.; Wan, B.

2013-07-01

256

Production and optical properties of Gd-loaded liquid scintillator for the RENO neutrino detector  

NASA Astrophysics Data System (ADS)

Reactor experiment for neutrino oscillation (RENO) began data-taking from August 2011. It successfully observed reactor antineutrino disappearance in April 2012 to measure the smallest mixing angle of ?13. Two identical detectors, one at near location and the other at far location, are constructed at the Yonggwang nuclear power plant in South Korea, to compare the observed reactor neutrino fluxes. Each RENO detector is filled with 16 mass tons of Gadolinium loaded liquid scintillator (GdLS) in the neutrino target region, and with 28 mass tons of unloaded liquid scintillator (LS) in the ?-catcher region surrounding the target. LS was developed to satisfy chemical, physical, optical properties, and safety requirements. Linear alkyl benzene (LAB) was chosen as a solvent because of its high flash-point, sufficient light yield, and being environmentally friendly. GdLS is carefully developed to keep a long attenuation length and high light yield for a long time period. In this paper, we report the characteristics and mass production of the RENO LS and GdLS.

Park, J. S.; Lee, J.; Yeo, I. S.; Choi, W. Q.; Ahn, J. K.; Choi, J. H.; Choi, S.; Choi, Y.; Jang, H. I.; Jang, J. S.; Jeon, E. J.; Joo, K. K.; Kim, B. R.; Kim, H. S.; Kim, J. Y.; Kim, S. B.; Kim, S. Y.; Kim, W.; Kim, Y. D.; Lee, J. H.; Lee, J. K.; Lim, I. T.; Ma, K. J.; Pac, M. Y.; Park, I. G.; Park, K. S.; Siyeon, K.; So, S. H.; Stepanyan, S. S.; Yu, I.

2013-04-01

257

Performance assessment of a 2D array of plastic scintillation detectors for IMRT quality assurance  

NASA Astrophysics Data System (ADS)

The purposes of this work are to assess the performance of a 2D plastic scintillation detectors array prototype for quality assurance in intensity-modulated radiation therapy (IMRT) and to determine its sensitivity and specificity to positioning errors of one multileaf collimator (MLC) leaf and one MLC leaf bank by applying the principles of signal detection theory. Ten treatment plans (step-and-shoot delivery) and one volumetric modulated arc therapy plan were measured and compared to calculations from two treatment-planning systems (TPSs) and to radiochromic films. The averages gamma passing rates per beam found for the step-and-shoot plans were 95.8% for the criteria (3%, 2 mm), 97.8% for the criteria (4%, 2 mm), and 98.1% for the criteria (3%, 3 mm) when measurements were compared to TPS calculations. The receiver operating characteristic curves for the one leaf errors and one leaf bank errors were determined from simulations (theoretical upper limits) and measurements. This work concludes that arrays of plastic scintillation detectors could be used for IMRT quality assurance in clinics. The use of signal detection theory could improve the quality of dosimetric verifications in radiation therapy by providing optimal discrimination criteria for the detection of different classes of errors.

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

2013-07-01

258

Scintillation detectors based on poly-2,4-dimethylstyrene: Structure peculiarities and radiation damage  

SciTech Connect

Scintillation detectors based on poly-2,4-dimethyl styrene (P-2,4-DMS) are studied. Investigated is the influence of two methyl groups present in the benzene ring on the energy, spectral and structural characteristics of the polymer. The said factors are assumed to result in the detectors high light output and radiation resistance. It is shown that under radiolysis (77 K) the radiation yield of the paramagnetic centers of P-2,4-DMS exceeds that of polystyrene (PST) by {approximately} 1.5. Unlike PST film, the luminescence spectra of P-2,4-DMS are characterized by the presence of both excimer (320-340 nm) and monomer (292 nm) bands. Revealed are the distinction in the nature of the optical characteristics of macroradicals and the efficiency of energy transfer in gamma-irradiated PST and P-2,4-DMS scintillators. The relation between the super-molecular structure of the polymers and the interaction of their macroradicals with molecular O{sub 2} is stated.

Gunder, O.A.; Voronkina, N.I.; Kopina, I.V. [Institute for Single Crystals, Kharkov (Ukraine)] [Institute for Single Crystals, Kharkov (Ukraine)

1995-08-01

259

Development of a real-time digital radiography system using a scintillator-type flat-panel detector  

NASA Astrophysics Data System (ADS)

In order to study the advantage and remaining problems of FPD (flat panel detector) for clinical use by the real-time DR (digital radiography) system, we developed a prototype system using a scintillator type FPD and which was compared with previous I.I.-CCD type real-time DR. We replaced the X- ray detector of DR-2000X from I.I.-4M (4 million pixels)-CCD camera to the scintillator type dynamic FPD(7' X 9', 127 micrometers ), which can take both radiographic and fluoroscopic images. We obtained the images of head and stomach phantoms, and discussed about the image quality with medical doctors.

Ikeda, Shigeyuki; Suzuki, Katsumi; Ishikawa, Ken; Okajima, Kenichi

2001-06-01

260

A method for the selection of the optimum counting conditions in a ZnS(Ag) scintillation detector.  

PubMed

The well-known criteria for the selection of the optimum counting conditions in a ZnS(Ag) scintillation detector seem to restrict its applicability. These do not consider simultaneously operating voltage and electronic threshold variation to reach the best counting conditions. Therefore, a more general method for the determination of the optimum counting conditions in ZnS(Ag) scintillation detectors is proposed. In this method, a relationship between voltage and electronic threshold is derived for counting efficiency. In order to test the method, quality control procedures have been carried out as well as the determination of gross alpha activity in environmental samples. PMID:10800726

Pujo, L; Suarez-Navarro, J A; Montero, M

2000-04-01

261

Scintillating plastic optical fiber radiation detectors in high energy particle physics.  

National Technical Information Service (NTIS)

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 techn...

A. D. Bross

1991-01-01

262

[Effects of ionizing radiation on scintillators and other particle detectors]. Conference summary  

SciTech Connect

It is my task to summarise the great variety of topics (covering a refreshing mix of physics, chemistry and technology) presented at this conference, which has focused on the effects of ionising radiation on scintillators and other particle detectors. One of the reasons and the central interest of many of the participants was the use of such detectors in experiments at two future large hadron colliders: the Superconducting Super Collider to be operating outside of Dallas in the United States by the turn of the decade and its European counterpart the Large Hadron Collider to be operating outside of Geneva in Switzerland on a similar time scale. These accelerators are the ``apple of the high energy physicist`s eye.`` Their goal is to uncover the elusive Higgs particle and thereby set the cornerstone in our current knowledge of elementary particle interactions. This is the Quest, and from this lofty height the presentations rapidly moved on to the specific questions of experimental science: how such an experiment is carried out; why radiation damage is an issue; how radiation damage affects detectors; which factors affect radiation damage characteristics; which factors are not affected by radiation damage; and how better detectors may be constructed. These were the substance of this conference.

Proudfoot, J.

1992-09-01

263

Monolithic scintillator PET detectors with intrinsic depth-of-interaction correction.  

PubMed

We developed positron emission tomography (PET) detectors based on monolithic scintillation crystals and position-sensitive light sensors. Intrinsic depth-of-interaction (DOI) correction is achieved by deriving the entry points of annihilation photons on the front surface of the crystal from the light sensor signals. Here we characterize the next generation of these detectors, consisting of a 20 mm thick rectangular or trapezoidal LYSO:Ce crystal read out on the front and the back (double-sided readout, DSR) by Hamamatsu S8550SPL avalanche photodiode (APD) arrays optimized for DSR. The full width at half maximum (FWHM) of the detector point-spread function (PSF) obtained with a rectangular crystal at normal incidence equals approximately 1.05 mm at the detector centre, after correction for the approximately 0.9 mm diameter test beam of annihilation photons. Resolution losses of several tenths of a mm occur near the crystal edges. Furthermore, trapezoidal crystals perform almost equally well as rectangular ones, while improving system sensitivity. Due to the highly accurate DOI correction of all detectors, the spatial resolution remains essentially constant for angles of incidence of up to at least 30 degrees . Energy resolutions of approximately 11% FWHM are measured, with a fraction of events of up to 75% in the full-energy peak. The coincidence timing resolution is estimated to be 2.8 ns FWHM. The good spatial, energy and timing resolutions, together with the excellent DOI correction and high detection efficiency of our detectors, are expected to facilitate high and uniform PET system resolution. PMID:19265203

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

2009-04-01

264

Monolithic scintillator PET detectors with intrinsic depth-of-interaction correction  

NASA Astrophysics Data System (ADS)

We developed positron emission tomography (PET) detectors based on monolithic scintillation crystals and position-sensitive light sensors. Intrinsic depth-of-interaction (DOI) correction is achieved by deriving the entry points of annihilation photons on the front surface of the crystal from the light sensor signals. Here we characterize the next generation of these detectors, consisting of a 20 mm thick rectangular or trapezoidal LYSO:Ce crystal read out on the front and the back (double-sided readout, DSR) by Hamamatsu S8550SPL avalanche photodiode (APD) arrays optimized for DSR. The full width at half maximum (FWHM) of the detector point-spread function (PSF) obtained with a rectangular crystal at normal incidence equals ~1.05 mm at the detector centre, after correction for the ~0.9 mm diameter test beam of annihilation photons. Resolution losses of several tenths of a mm occur near the crystal edges. Furthermore, trapezoidal crystals perform almost equally well as rectangular ones, while improving system sensitivity. Due to the highly accurate DOI correction of all detectors, the spatial resolution remains essentially constant for angles of incidence of up to at least 30°. Energy resolutions of ~11% FWHM are measured, with a fraction of events of up to 75% in the full-energy peak. The coincidence timing resolution is estimated to be 2.8 ns FWHM. The good spatial, energy and timing resolutions, together with the excellent DOI correction and high detection efficiency of our detectors, are expected to facilitate high and uniform PET system resolution.

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

2009-04-01

265

Progress of performance of MOEMS micro spectrometers through enhanced signal processing, detectors and system setup  

NASA Astrophysics Data System (ADS)

Micro spectrometers have been realized by the use of MEMS based scanning grating chips several years ago. The main advantage is the requirement of a single detector instead of a detector array for micro spectrometers applying fixed gratings. Especially in the near infrared range beyond the detection limit of silicon detectors, this can help to reduce the system costs significantly. First measurements for test application have been performed successfully. Industrial applications require wide spectral range, high long term stability and sufficient computation power in the system itself to realize intelligent sensor heads for process monitoring and quality control. Through the recent time, many details have been improved. Extended InGaAs detectors have been used to extend the spectral range up to 2500nm. Improvements of the grating position readout improved the wavelength stability of the system even under tough operation conditions. The integration of faster digital signal processors opens the possibility to implement spectral evaluation algorithms into the system itself. Besides simple applications shown earlier like the selection of different kinds of plastic waste, now a more quantitative analysis can be achieved. For example the ethanol content of liquor samples has been measured and evaluated quantitatively.

Grüger, Heinrich; Egloff, Thomas; Messerschmidt, Matthias; Scholles, Michael

2008-09-01

266

Registration of Forbush decrease 2012/03/08 with a global net of the thermal neutron scintillation en-detectors  

NASA Astrophysics Data System (ADS)

Forbush decrease was recorded for the first time with a global net of the neutron scintillation detectors (en-detectors) developed in INR RAS. The detectors are located at four geographic points: Baksan (43E, 43N), Gran Sasso, Italy (13E, 42N), Moscow (37E, 56N) and Obninsk (38E, 55N). This experimental fact by itself shows not only the possibility of using the detectors for cosmic ray variations study but also unbiasly supports the nuclear physics method developed by us as a novel instrument both for geophysical researches and for neutron environment monitoring.

Alekseenko, V.; Arneodo, F.; Bruno, G.; Fulgione, W.; Gromushkin, D.; Shchegolev, O.; Stenkin, Yu; Stepanov, V.; Sulakov, V.

2013-02-01

267

Measurement of 14.1 MeV neutrons with a Th-scintillator optical fibre detector  

Microsoft Academic Search

The flux of 14.1MeV neutrons was measured with high spatial resolution in the vicinity of the target of a D–T neutron generator. The measurements were made by a thin optical fibre detector with a ZnS(Ag) scintillation tip mixed with a 232Th neutron converter. The detector concept was originally developed at Nagoya University. The flux of 14.1MeV neutrons could be measured

Y. Yamane; P. Lindén; J. K. H. Karlsson; I. Pázsit

1998-01-01

268

Measurement of the cross section for inverse. beta. decay by a scintillation detector at the Rovno Nuclear Power Plant  

Microsoft Academic Search

The parameters of a scintillation detector designed to observe the reaction nu-bar\\/sub e\\/+p ..-->.. e\\/sup +\\/+n through delayed positron-neutron coincidences have been improved in the neutrino laboratory at the Rovno Nuclear Power Plant. The shielding of the detector has been increased and the background has been reduced. The threshold for positron detection is decreased to 0.6 MeV, the time interval

A. I. Afonin; S. A. Bogatov; A. A. Borovoi; A. G. Vershinskii; S. L. Gavrilov; Y. L. Dobrynin; S. N. Ketov; Y. V. Klimov; V. I. Kopeikin; L. A. Levina

1985-01-01

269

Measurement of cosmic-ray origin neutrons using a scintillation detector at the summit of Mt. Fuji  

Microsoft Academic Search

Cosmic-ray origin neutrons were measured with a scintillation detector at the summit of Mt. Fuji at an altitude of 3776 m during the summer of 2008. The averaged neutron ambient dose equivalent rate converted from the count rates of the detector was 0.47 ± 0.001 ?Sv h?1, which is approximately four times greater than the calculated value of 0.11 ± 0.01 ?Sv h?1. It is postulated that the discrepancy

Kazuaki Yajima; Hiroshi Yasuda

270

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

271

Double Chooz: optimizing the sensitivity to ?13 with a multi-detector setup  

NASA Astrophysics Data System (ADS)

The best upper limit to the neutrino mixing angle ?13 is set by the CHOOZ experiment. The eventual measurement of ?13 in reactor neutrino experiments relies on a reduction of the CHOOZ systematics of about 1 order of magnitude, along with a major increase of the luminosity. Provided that enough statistics are achieved, fighting the systematics becomes the key towards ?13. The Double Chooz experiment engages this fight with a multi-detector set up.

Novella, P.; Double Chooz Collaboration

2012-08-01

272

Reply to “Some remarks on the article ‘Photoelectron anticorrelations and sub-Poisson statistics in scintillation detectors’”  

NASA Astrophysics Data System (ADS)

When Prof. Samedov's result is properly interpreted for scintillation detectors, it is correct, but it does not provide a robust method for estimating the Fano factor for optical photons because it depends on accurate knowledge of the mean number of photons produced by a particular sample.

Bousselham, Abdelkader; Barrett, Harrison H.; Bora, Vaibhav; Shah, Kanai

2012-11-01

273

Theoretical response of a ZnS(Ag) scintillation detector to alpha-emitting sources and suggested applications  

Microsoft Academic Search

The classic problem of alpha absorption is discussed in terms of the quantitative determination of the activity of weightless alpha sources and the specific alpha activity of extended sources accounting for absorption in the source medium and the window of a large area ZnS(Ag) scintillation detector. The relationship for the expected counting rate gamma of a monoenergetic source of active

K. W. Skrable; K. A. Phoenix; G. E. Chabot; C. S. French; M. Jo; G. A. Falo

1991-01-01

274

A detector to measure lithium-9 production rate in liquid scintillator at the earth's surface by cosmic ray muons  

Microsoft Academic Search

The next generation of nuclear fission reactor based neutrino experiments seeking to measure the theta13 mixing angle rely upon measurements made by detectors placed close to the reactor, and therefore less shielded from cosmic ray muons by the earth. 9Li production in liquid scintillator by these cosmic ray muons becomes a serious problem for these experiments that must be dealt

Mark A. Smith

2009-01-01

275

Homestake Tracking Spectrometer: A One-Mile Deep 1400-Ton Liquid-Scintillation Nucleon-Decay Detector.  

National Technical Information Service (NTIS)

We describe a proposed nucleon decay detector able to demonstrate the existence of nucleon decay for lifetimes up to 5 x 10 exp 32 yr. The proposed instrument is a self-vetoed completely-active 1400-ton liquid scintillation Tracking Spectrometer to be loc...

M. L. Cherry I. Davidson K. Lande C. K. Lee E. Marshall

1982-01-01

276

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

1998-06-01

277

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

SciTech Connect

We present construction methods and performance results for a production scintillator array of 64 optically isolated, 3 mm x 3 mm x 30 mm sized LSO crystals. This scintillator array has been developed for a PET detector module consisting of the 8x8 LSO array coupled on one end to a single photomultiplier tube (PMT) and on the opposite end to a 64 pixel array of silicon photodiodes (PD). The PMT provides an accurate timing pulse and initial energy discrimination, the PD identifies the crystal of interaction, the sum provides a total energy signal, and the PD/(PD+PMT) ratio determines the depth of interaction (DOI). Unlike the previous LSO array prototypes, we now glue Lumirror reflector material directly onto 4 sides of each crystal to obtain an easily manufactured, mechanically rugged array with our desired depth dependence. With 511 keV excitation, we obtain a total energy signal of 3600 electrons, pulse-height resolution of 25% fwhm, and 6-15 mm fwhm DOI resolution.

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

2000-10-30

278

A pulse shape discrimination gamma-ray detector based on a silicon drift chamber coupled to a CsI(Tl) scintillator: prospects for a 1 keV1 MeV monolithic detector  

Microsoft Academic Search

In this paper, an X- and gamma-ray detector based on a silicon drift detector (SDD) coupled to a CsI(Tl) scintillating crystal is presented. The SDD is operated both as a direct X-ray detector for photons interacting in silicon and as an indirect detector for photons interacting in the scintillator. As interactions in silicon and in CsI yield different amounts of

Martino Marisaldi; Claudio Labanti; Heike Soltau

2004-01-01

279

Development of a gadolinium-loaded liquid scintillator for the Hanaro short baseline prototype detector  

NASA Astrophysics Data System (ADS)

We propose a new experiment on the site of the Korea Atomic Energy Research Institute (KAERI) located at Daejeon, Korea. The Hanaro short baseline (SBL) nuclear reactor with a thermal power output 30 MW is used to investigate a reactor neutrino anomaly. A Hanaro SBL prototype detector having a 60- l volume has been constructed ˜6 m away from the reactor core. A gadolinium (Gd)-loaded liquid scintillator (LS) is used as an active material to trigger events. The selection of the LS is guided by physical and technical requirements, as well as safety considerations. A linear alkyl benzene (LAB) is used as a base solvent of the Hanaro SBL prototype detector. Three g/ l of PPO and 30 mg/ l of bis-MSB are dissolved to formulate the LAB-based LS. Then, a 0.5% gadolinium (Gd) complex with carboxylic acid is loaded into the LAB-based LS by using the liquidliquid extraction method. In this paper, we will summarize all the characteristics of the Gd-loaded LAB-based LS for the Hanaro prototype detector.

Yeo, In Sung; Joo, Kyung Kwang; So, Sun Heang; Song, Sook Hyung; Kim, Hong Joo; So, Jung Ho; Park, Kang Soon; Ma, Kyung Ju; Jeon, Eun Ju; Kim, Jin Yu; Kim, Young Duk; Lee, Jason; Lee, Jeong-Yeon; Sun, Gwang-Min

2014-02-01

280

Novel Wavelength Shifting Collection Systems for Vacuum Ultraviolet Scintillation Photons in in Noble Gas Detectors  

NASA Astrophysics Data System (ADS)

Detection of vacuum ultraviolet (VUV) photons presents a challenge because this band of the electromagnetic spectrum has a short enough wavelength to scatter off of most (though not all) materials, but is not energetic enough to penetrate into the bulk of a detector (so cannot be treated calorimetrically like x rays or ? rays). This is exactly the band in which noble gasses (which make excellent media for radiation detectors) scintillate. VUV photon detection usually involves shifting them to visible wavelengths with a fluorescent molecule deposited on an optically clear surface viewed by a photosensor. Such techniques, while comparatively efficient and simple to fabricate, have high cost and complexity per unit coverage area making them prohibitively expensive and complicated to scale up to the very large sizes necessary for the next generation of neutrino, dark matter, and other rare event search experiments. We present several lines of inquiry attempting to address this problem, focusing on solutions that are directly applicable to a variety of current or next generation noble gas detectors. This line of R&D is a potentially fruitful avenue capable of furthering the goals of many experiments with a broad portfolio of fundamental and applied research.

Gehman, Victor

2013-04-01

281

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

282

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

283

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

284

Development of SiPM-based scintillator tile detectors for a multi-layer fast neutron tracker  

NASA Astrophysics Data System (ADS)

We are developing thin tile scintillator detectors with silicon photomultiplier (SiPM) readout for use in a multi-layer fast-neutron tracker. The tracker is based on interleaved Timepix and plastic scintillator layers. The thin 15 × 15 × 2 mm plastic scintillators require suitable optical readout in order to detect and measure the energy lost by energetic protons that have been recoiled by fast neutrons. Our first prototype used dual SiPMs, coupled to opposite edges of the scintillator tile using light-guides. An alternative readout geometry was designed in an effort to increase the fraction of scintillation light detected by the SiPMs. The new prototype uses a larger SiPM array to cover the entire top face of the tile. This paper details the comparative performance of the two prototype designs. A deuterium-tritium (DT) fast-neutron source was used to compare the relative light collection efficiency of the two designs. A collimated UV light source was scanned across the detector face to map the uniformity. The new prototype was found to have 9.5 times better light collection efficiency over the original design. Both prototypes exhibit spatial non-uniformity in their response. Methods of correcting this non-uniformity are discussed.

Preston, R.; Jakubek, J.; Prokopovich, D.; Uher, J.

2012-10-01

285

New gas detector setup for on-axis STIM tomography experiments  

NASA Astrophysics Data System (ADS)

A gas flow ionization chamber for use with on-axis scanning transmission ion microscopy tomography (STIM-T) has been developed. The entrance window is composed of a square silicon nitride membrane 100 nm thick and 1 mm2 in area. The use of this type of window does not add significantly to the energy resolution with the MeV H+ or He+ particles used in STIM, and proved to be resistant to high proton fluence in the irradiated spot. The ability of such detector to withstand direct beam hit with acceptable energy resolution makes it suitable for on-axis STIM-T, in this respect outperforming the more standard Si PIN diodes, which performance is known to degrade above fluences of ˜1010-1012 cm-2. The present in-line design while allowing easy mounting of the detector to the existing target chamber, has the peculiarity of providing a practical way of replacing the Si3N4 membrane in case it brakes while operating. The concept of gas ionization chamber under development is expected to become ideal for on-axis STIM-T experiments due to its low ageing during operation, and anticipated attainable speed and energy resolution.

Marques, A. C.; Fraga, M. M. F. R.; Fonte, P.; Beasley, D. G.; Alves, L. C.; da Silva, R. C.

2013-07-01

286

Characterization of scintillator materials for fast-ion loss detectors in nuclear fusion reactors  

NASA Astrophysics Data System (ADS)

In fusion plasma reactors, fast ion generated by heating systems and fusion born particles must be well confined. The presence of magnetohydrodynamic (MHD) instabilities can lead to a significant loss of these ions, which may reduce drastically the heating efficiency and may cause damage to plasma facing components in the vacuum vessel. In order to understand the physics underlying the fast ion loss mechanism, scintillator based detectors have been installed in several fusion devices. In this work we present the absolute photon yield and its degradation with ion fluence in terms of the number of photons emitted per incident ion of several scintillators thin coatings: SrGa2S4:Eu2+ (TG-Green), Y3Al5O12:Ce3+ (P46) and Y2O3:Eu3+ (P56) when irradiated with light ions of different masses (deuterium ions, protons and ?-particles) at energies between approximately 575 keV and 3 MeV. The photon yield will be discussed in terms of the energy deposited by the particles into the scintillator. For that, the actual composition and thickness of the thin layers were determined by Rutherford Backscattering Spectrometry (RBS). A collimator with 1 mm of diameter, which defines the beam size for the experiments, placed at the entrance of the chamber. An electrically isolated sample holder biased to +300 V to collect the secondary electrons, connected to a digital current integrator (model 439 by Ortec) to measure the incident beam current. A home made device has been used to store the real-time evolution of the beam current in a computer file allowing the correction of the IL yields due to the current fluctuations. The target holder is a rectangle of 150 × 112 mm2 and can be tilted. The X and Y movements are controlled through stepping motors, which permits a fine control of the beam spot positioning as well as the study of several samples without venting the chamber. A silica optical fiber of 1 mm diameter fixed to the vacuum chamber, which collects the light from the scintillators. The solid angle subtended by the fiber is ?2.2 × 10-5 sr. The final element is a compact and high sensitive spectrometer, QE6500 (Ocean Optics Inc.) with a 2D area detector which allow us to measure simultaneously in the range of 200-1100 nm with a spectral resolution ?1-2 nm. The measured signals were analyzed and stored with the SpectraSuite software [6]. The absolute calibration of the optical system described above was carried out with a HL-2000-CAL Tungsten Halogen Calibration Standard light source which provides absolute intensity values (in ?W/cm2/nm) at the fiber port at wavelengths from 360-1050 nm.The beam fluxes used to irradiate the phosphors were ? 1012 p/cm2s- for the IL yields determination, and up to ten times higher for the degradation analyses.The Rutherford Backscattering Spectrometry (RBS) measurements of the screens were accomplished in the same vacuum chamber using protons at 3 MeV and 5 MeV. Two different energies were employed due to the large difference between the thicknesses of the samples. The proton beam intensity was 10 nA and the beam size 1 mm of diameter. The analysis were performed with a Passivated Implanted Planar Silicon (PIPS) detector of 300 mm2, positioned at 150° and with a 10 ?m thick aluminized mylar foil placed at the detector surface to avoid the light emitted by the scintillators. The RBS spectra were analyzed using the SIMNRA code [7].The scintillators investigated in this work were selected according to their availability, radiation hardness, fast response, and/or prior use in plasma diagnostics. In this paper, three different kinds of materials have been analyzed. The TG-Green (so called by the manufacturer, Sarnoff Corporation, USA) is a Eu doped SrGa2S4 powder substrate with density of 3.65 g/cm3, and presents an emission at 540 nm with a very short decay time.?490 ns [8]. A TG-Green scintillator coating has been applied, for the first time, to a fusion plasma diagnostics for the detection of fast-particle losses on the AUG tokamak [9,10]. The same material supplied by other manufacturer (CIEMAT)

Jiménez-Ramos, M. C.; García López, J.; García-Muñoz, M.; Rodríguez-Ramos, M.; Carmona Gázquez, M.; Zurro, B.

2014-08-01

287

Development of neutron-monitor detector using liquid organic scintillator coupled with 6Li + ZnS(Ag) Sheet.  

PubMed

A phoswitch-type detector has been developed for monitoring neutron doses in high-energy accelerator facilities. The detector is composed of a liquid organic scintillator (BC501A) coupled with ZnS(Ag) sheets doped with 6Li. The dose from neutrons with energies above 1 MeV is evaluated from the light output spectrum of the BC501A by applying the G-function, which relates the spectrum to the neutron dose directly. The dose from lower energy neutrons, on the other hand, is estimated from the number of scintillations emitted from the ZnS(Ag) sheets. Characteristics of the phoswitch-type detector were studied experimentally in some neutron fields. It was found from the experiments that the detector has an excellent property of pulse-shape discrimination between the scintillations of BC501A and the ZnS(Ag) sheets. The experimental results also indicate that the detector is capable of reproducing doses from thermal neutrons as well as neutrons with energies from one to several tens of megaelectronvolts (MeV). PMID:15353655

Sato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Takahashi, Fumiaki

2004-01-01

288

On the use of a single-fiber multipoint plastic scintillation detector for 192Ir high-dose-rate brachytherapy  

PubMed Central

Purpose: The goal of this study was to prove the feasibility of using a single-fiber multipoint plastic scintillation detector (mPSD) as an in vivo verification tool during 192Ir high-dose-rate brachytherapy treatments. Methods: A three-point detector was built and inserted inside a catheter-positioning template placed in a water phantom. A hyperspectral approach was implemented to discriminate the different optical signals composing the light output at the exit of the single collection optical fiber. The mPSD was tested with different source-to-detector positions, ranging from 1 to 5 cm radially and over 10.5 cm along the longitudinal axis of the detector, and with various integration times. Several strategies for improving the accuracy of the detector were investigated. The device's accuracy in detecting source position was also tested. Results: Good agreement with the expected doses was obtained for all of the scintillating elements, with average relative differences from the expected values of 3.4 ± 2.1%, 3.0 ± 0.7%, and 4.5 ± 1.0% for scintillating elements from the distal to the proximal. A dose threshold of 3 cGy improved the general accuracy of the detector. An integration time of 3 s offered a good trade-off between precision and temporal resolution. Finally, the mPSD measured the radioactive source positioning uncertainty to be no more than 0.32 ± 0.06 mm. The accuracy and precision of the detector were improved by a dose-weighted function combining the three measurement points and known details about the geometry of the detector construction. Conclusions: The use of a mPSD for high-dose-rate brachytherapy dosimetry is feasible. This detector shows great promise for development of in vivo applications for real-time verification of treatment delivery.

Therriault-Proulx, Francois; Beddar, Sam; Beaulieu, Luc

2013-01-01

289

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

290

Determination of neutron-induced alpha-particle cross sections on carbon using the response of a liquid scintillation detector  

SciTech Connect

This paper presents the sums of the cross section {sup 12}C(n, {alpha}{sub 0}) {sup 9}Be and {sup 12}C(n, N{prime}3{alpha}) determined in the neutron energy range between 7.4 and 11 MeV. An NE-213 scintillation detector is simultaneously used as a carbon target, an alpha-particle detector, and a neutron fluence monitor. By comparing the measured and calculated response spectra, the neutron-induced alpha-particle events in the scintillation volume are separated and the cross sections {sigma}{sub n,{alpha}0} + {sigma}{sub n,n{prime}3{alpha}} are determined relative to the n-p scattering cross section. The pulse-height distribution due to alpha particles allows the angular distribution to be extracted on the basis of the reaction kinematics and an accurately determined light output function for alpha particles in the NE-213 detector.

Brede, H.J.; Dietze, G.; Klein, H.; Schoelermann, H. (Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-3300 Braunschweig (DE))

1991-01-01

291

Low background detector with enriched 116CdWO4 crystal scintillators to search for double ? decay of 116Cd  

NASA Astrophysics Data System (ADS)

A cadmium tungstate crystal boule enriched in 116Cd to 82% with mass of 1868 g was grown by the low-thermal-gradient Czochralski technique. The isotopic composition of cadmium and the trace contamination of the crystal were estimated by High Resolution Inductively Coupled Plasma Mass-Spectrometry. The crystal scintillators produced from the boule were subjected to characterization that included measurements of transmittance and energy resolution. A low background scintillation detector with two 116CdWO4 crystal scintillators (586 g and 589 g) was developed. The detector was running over 1727 h deep underground at the Gran Sasso National Laboratories of the INFN (Italy), which allowed to estimate the radioactive contamination of the enriched crystal scintillators. The radiopurity of a third 116CdWO4 sample (326 g) was tested with the help of ultra-low background high purity germanium ? detector. Monte Carlo simulations of double ? processes in 116Cd were used to estimate the sensitivity of an experiment to search for double ? decay of 116Cd.

Barabash, A. S.; Belli, P.; Bernabei, R.; Boiko, R. S.; Cappella, F.; Caracciolo, V.; Chernyak, D. M.; Cerulli, R.; Danevich, F. A.; Di Vacri, M. L.; Dossovitskiy, A. E.; Galashov, E. N.; Incicchitti, A.; Kobychev, V. V.; Konovalov, S. I.; Kovtun, G. P.; Kudovbenko, V. M.; Laubenstein, M.; Mikhlin, A. L.; Nisi, S.; Poda, D. V.; Podviyanuk, R. B.; Polischuk, O. G.; Shcherban, A. P.; Shlegel, V. N.; Solopikhin, D. A.; Stenin, Yu G.; Tretyak, V. I.; Umatov, V. I.; Vasiliev, Ya V.; Virich, V. D.

2011-08-01

292

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

293

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

294

Ceramic Scintillators  

NASA Astrophysics Data System (ADS)

Scintillators are the primary radiation sensor in many applications such as medical diagnostics, medical radiographs, and industrial component inspection. Some of the limitations in the properties of single-crystal scintillators are discussed for imaging applications, and the advantages of a new class of polycrystalline ceramic scintillators are described in detail. After the important scintillator properties of transparency, X-ray stopping power, light output, primary speed, luminescent afterglow, and radiation damage are described, the processing and performance of ceramic scintillators (Y,Gd)2O3:Eu,Pr; Gd2O2S:Pr,Ce,F; and Gd3Ga5O12:Cr,Ce are discussed. Ceramic scintillator uses and trends are presented in light of issues related to their uses in advanced medical and industrial X-ray detectors for CT imaging applications. Finally, some of the challenges are given for successfully developing a polycrystalline ceramic scintillator for use in photon-counting applications.

Greskovich, C.; Duclos, S.

1997-08-01

295

Study on the energy response to neutrons for a new scintillating-fiber-array neutron detector  

NASA Astrophysics Data System (ADS)

The energy response of a new scintillating-fiber-array neutron detector to neutrons in the energy range 0.01 MeV?E n?14 MeV was modeled by combining a simplified Monte Carlo model and the MCNP 4b code. In order to test the model and get the absolute sensitivity of the detector to neutrons, one experiment was carried out for 2.5 and 14 MeV neutrons from T(p,n) 3He and T(d,n) 4He reactions at the Neutron Generator Laboratory at the Institute of Modern Physics, the Chinese Academy of Science. The absolute neutron fluence was obtained with a relative standard uncertainty 4.5% or 2.0% by monitoring the associated protons or 4He particles, respectively. Another experiment was carried out for 0.5, 1.0, 1.5, 2.0, 2.5 MeV neutrons from T(p,n) 3He reaction, and for 3.28, 3.50, 4.83, 5.74 MeV neutrons from D(d,n) 3He reaction on the Model 5SDH-2 accelerator at China Institute of Atomic Energy. The absolute neutron fluence was obtained with a relative standard uncertainty 5.0% by using a calibrated long counter. The results show that the calculated absolute sensitivity from the model agrees with the experimental data considering the expanded relative uncertainty 15% in the experiments.

Zhang, Qianmei; Wang, Qunshu; Xie, Zhongsheng; Niu, Shengli

2003-01-01

296

An X-ray area detector with scintillating glass fiber optics  

Microsoft Academic Search

We are investigating a prototype X-ray imaging system in which scintillating fiber-optic glass plates are fiber-optically coupled to an intensified CCD camera. Scintillating fiber optics combine scintillating material with a waveguide permitting an increase in the thickness of the scintillating material and therefore preserving the spatial resolution with increased detection efficiency for high-energy X-rays. Experimental evaluation of the spatial resolution,

P. Ottonello; G. A. Rottigni; G. Zanella; R. Zannoni

1992-01-01

297

Comparison of photon counting and conventional scintillation detectors in a pinhole SPECT system for small animal imaging: Monte carlo simulation studies  

NASA Astrophysics Data System (ADS)

The photon counting detector based on cadmium telluride (CdTe) or cadmium zinc telluride (CZT) is a promising imaging modality that provides many benefits compared to conventional scintillation detectors. By using a pinhole collimator with the photon counting detector, we were able to improve both the spatial resolution and the sensitivity. The purpose of this study was to evaluate the photon counting and conventional scintillation detectors in a pinhole single-photon emission computed tomography (SPECT) system. We designed five pinhole SPECT systems of two types: one type with a CdTe photon counting detector and the other with a conventional NaI(Tl) scintillation detector. We conducted simulation studies and evaluated imaging performance. The results demonstrated that the spatial resolution of the CdTe photon counting detector was 0.38 mm, with a sensitivity 1.40 times greater than that of a conventional NaI(Tl) scintillation detector for the same detector thickness. Also, the average scatter fractions of the CdTe photon counting and the conventional NaI(Tl) scintillation detectors were 1.93% and 2.44%, respectively. In conclusion, we successfully evaluated various pinhole SPECT systems for small animal imaging.

Lee, Young-Jin; Park, Su-Jin; Lee, Seung-Wan; Kim, Dae-Hong; Kim, Ye-Seul; Kim, Hee-Joung

2013-05-01

298

An X-ray imaging gas scintillation detector with CsI-wire chamber UV-photon readout  

NASA Astrophysics Data System (ADS)

UV-photons from an Xe-filled gas scintillation counter are detected with a CsI photocathode coupled to a double stage, low-pressure wire chamber. The high quantum efficiency, (9 pct), of the UV-detector yields a high detection efficiency of both primary and secondary scintillation photons. An energy resolution of 4.1 pct (FWHM) was recorded with 60 keV X-rays, inducing secondary scintillation in 5 bar of Xe; the wire chamber operated at 20 Torr of CH4. The two-dimensional planar localization of UV-photons, combined with the drift time measurement of primary electrons, provides a three-dimensional, multihit, imaging capability of X-ray photon interactions, with a resolution of 2-3 mm (FWHM). The stability of the CsI photocathode under different operation conditions and its sensitivity to exposure to air are discussed.

Dangendorf, V.; Breskin, A.; Chechik, R.; Schmidt-Boecking, H.

1990-07-01

299

Possibility of thermal stabilization of the optical system of a scintillation detector  

Microsoft Academic Search

The scintillation method remains one of the most effective methods in the detection of ionizing radiation, which is why it is important to enhance the performance characteristics of the optical systems. Analysis of present-day devices based on inorganic crystal scintillators shows that during use at a high (above 150°C) temperature the scintillation characteristics deteriorate irreversibly from measurement to measurement. Crystalline

B. V. Grinev; E. D. Kovtun; A. N. Protsenko; V. L. Yankelevich

1992-01-01

300

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

301

Development of InP solid state detector and liquid scintillator containing indium complexes for a measurement of pp/7Be solar neutrinos  

NASA Astrophysics Data System (ADS)

Am semi-insulating indium phosphide detector has been developed for IPNOS experiment and it could detect both ?'s and the scintillation light. We have also developed an organic liquid scintillator which contains indium and zirconium complexes, and found the gamma-ray-induced luminescence of 8-quinolinol metal complexes.

Fukuda, Yoshiyuki; Ipnos Collaboration

2012-08-01

302

Monte Carlo investigations of megavoltage cone-beam CT using thick, segmented scintillating detectors for soft tissue visualization  

SciTech Connect

Megavoltage cone-beam computed tomography (MV CBCT) is a highly promising technique for providing volumetric patient position information in the radiation treatment room. Such information has the potential to greatly assist in registering the patient to the planned treatment position, helping to ensure accurate delivery of the high energy therapy beam to the tumor volume while sparing the surrounding normal tissues. Presently, CBCT systems using conventional MV active matrix flat-panel imagers (AMFPIs), which are commonly used in portal imaging, require a relatively large amount of dose to create images that are clinically useful. This is due to the fact that the phosphor screen detector employed in conventional MV AMFPIs utilizes only {approx}2% of the incident radiation (for a 6 MV x-ray spectrum). Fortunately, thick segmented scintillating detectors can overcome this limitation, and the first prototype imager has demonstrated highly promising performance for projection imaging at low doses. It is therefore of definite interest to examine the potential performance of such thick, segmented scintillating detectors for MV CBCT. In this study, Monte Carlo simulations of radiation energy deposition were used to examine reconstructed images of cylindrical CT contrast phantoms, embedded with tissue-equivalent objects. The phantoms were scanned at 6 MV using segmented detectors having various design parameters (i.e., detector thickness as well as scintillator and septal wall materials). Due to constraints imposed by the nature of this study, the size of the phantoms was limited to {approx}6 cm. For such phantoms, the simulation results suggest that a 40 mm thick, segmented CsI detector with low density septal walls can delineate electron density differences of {approx}2.3% and 1.3% at doses of 1.54 and 3.08 cGy, respectively. In addition, it was found that segmented detectors with greater thickness, higher density scintillator material, or lower density septal walls exhibit higher contrast-to-noise performance. Finally, the performance of various segmented detectors obtained at a relatively low dose (1.54 cGy) was compared with that of a phosphor screen similar to that employed in conventional MV AMFPIs. This comparison indicates that for a phosphor screen to achieve the same contrast-to-noise performance as the segmented detectors {approx}18 to 59 times more dose is required, depending on the configuration of the segmented detectors.

Wang Yi; Antonuk, Larry E.; El-Mohri, Youcef; Zhao Qihua; Sawant, Amit; Du Hong [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2008-01-15

303

Monte Carlo investigations of megavoltage cone-beam CT using thick, segmented scintillating detectors for soft tissue visualization  

PubMed Central

Megavoltage cone-beam computed tomography (MY CBCT) is a highly promising technique for providing volumetric patient position information in the radiation treatment room. Such information has the potential to greatly assist in registering the patient to the planned treatment position, helping to ensure accurate delivery of the high energy therapy beam to the tumor volume while sparing the surrounding normal tissues. Presently, CBCT systems using conventional MV active matrix flat-panel imagers (AMFPIs), which are commonly used in portal imaging, require a relatively large amount of dose to create images that are clinically useful. This is due to the fact that the phosphor screen detector employed in conventional MV AMFPIs utilizes only ~2% of the incident radiation (for a 6 MV x-ray spectrum). Fortunately, thick, segmented scintillating detectors can overcome this limitation, and the first prototype imager has demonstrated highly promising performance for projection imaging at low doses. It is therefore of definite interest to examine the potential performance of such thick, segmented scintillating detectors for MV CBCT. In this study, Monte Carlo simulations of radiation energy deposition were used to examine reconstructed images of cylindrical CT contrast phantoms, embedded with tissue-equivalent objects. The phantoms were scanned at 6 MV using segmented detectors having various design parameters (i.e., detector thickness, as well as scintillator and septal wall materials). Due to constraints imposed by the nature of this study, the size of the phantoms was limited to ~6 cm. For such phantoms, the simulation results suggest that a 40 mm thick, segmented CsI detector with low density septal walls can delineate electron density differences of ~2.3% and 1.3% at doses of 1.54 and 3.08 cGy, respectively. In addition, it was found that segmented detectors with greater thickness, higher density scintillator material, or lower density septal walls exhibit higher contrast-to-noise performance. Finally, the performance of various segmented detectors obtained at a relatively low dose (1.54 cGy) was compared to that of a phosphor screen similar to that employed in conventional MV AMFPIs. This comparison indicates that, for a phosphor screen to achieve the same contrast-to-noise performance as the segmented detectors, ~18 to 59 times more dose is required, depending on the configuration of the segmented detectors.

Wang, Yi; Antonuk, Larry E; El-Mohri, Youcef; Zhao, Qihua; Sawant, Amit; Du, Hong

2010-01-01

304

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

305

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

306

Proton beam characterisation of a prototype thin-tile plastic scintillator detector with SiPM readout for use in fast-neutron tracker  

NASA Astrophysics Data System (ADS)

We present details of the construction and characterisation of a prototype thin-tile plastic scintillation detector for use in a multi-layer Fast Neutron Tracker. Scintillation light is read out using solid-state silicon photomultiplier detectors (SiPMs). The Tracker consists of alternating scintillator and Timepix detector layers. The scintillator tile provides a hydrogen-rich target, in which impinging fast neutrons produce recoil protons. The energies lost by protons in the plastic scintillator are measured and recoil protons exiting the scintillator are tracked in the Timepix detector. The combination of signals from the scintillator and Timepix provides information to reconstruct the energy or direction of the impinging neutron, using calculations based on the kinematics of the elastic neutron scattering. Three prototype scintillation detectors were constructed, using either a pair of 3 × 3 mm sensitive area SPMMicro3035 SiPMs from SensL or a pair of MAPD-3n SiPMs from Zecotek. The detector performances were characterised using a mono-energetic proton beam. An absolute energy calibration was measured at 3, 4 and 5 MeV proton energies with good linearity. The best measured energy resolution was 29.8% at 5 MeV. Spatial uniformity was assessed by measuring the response across the detector face. Finally, the tile detector's ability to provide a trigger for Timepix acquisition in the stack configuration was demonstrated for single and double neutron recoil events using a DT neutron source. The SiPM-based design was found to be well-suited for the application of the multi-layer fast neutron tracker.

Preston, R.; Jakubek, J.; Prokopovich, D.; Uher, J.

2012-02-01

307

Investigation of the Performance of Scintillator-Based CMOS Flat Panel Detectors for X-Ray and Thermal Neutron Imaging  

Microsoft Academic Search

Recent advances in of silicon-based CMOS (complementary metal-oxide-semiconductor) flat panel detectors have resulted in an attractive use of cost-effective radiation imaging devices for X-ray and neutron radiography\\/tomography system. Indirect detection methods consisted of an X-ray converter (or a scintillator screen) and photodiode arrays are more widely used in high resolution micro-CT (computed tomography), dental and industrial NDT applications. In this

Bo Kyung Cha; Jong Yul Kim; Tae Joo Kim; Yikyung Kim; Cheulmuu Sim; Seung Wook Lee; Gyuseong Cho

2010-01-01

308

Determination of mass attenuation coefficients of some boron ores at 59.54keV by using scintillation detector.  

PubMed

The mass attenuation coefficients of the 59.54keV radiation of (241)Am point source in boron ores such as tincal, ulexite and colemanite were determined experimentally by a scintillation detector and theoretically. Since boron ores contain boron, hydrogen, and a lot of elements, they may be used as shielding against neutrons and gammas simultaneously, e.g. for shielding (241)Am/Be neutron sources, as they emit both gammas and neutrons. PMID:19800806

Demir, Faruk

2010-01-01

309

Gamma-ray spectroscopy with LaBr3:Ce scintillator readout by a silicon drift detector  

Microsoft Academic Search

In this work we propose a gamma-ray spectrometer based on a LaBr3:Ce scintillator coupled to a silicon drift detector (SDD). The SDD is a photodetector characterized by a very low noise thanks to the low value of output capacitance independent from the active area. With respect to a PMT, the SDD offers a higher quantum efficiency which reduces the spread

C. Fiorini; A. Gola; M. Zanchi; A. Longoni; P. Lechner; H. Soltau; L. Struder

2005-01-01

310

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

311

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  

PubMed Central

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 mm3) 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 25×25 cm2, 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

2011-01-01

312

Clinical Trials of a Urethral Dose Measurement System in Brachytherapy Using Scintillation Detectors  

SciTech Connect

Purpose: To report on the clinical feasibility of a novel scintillation detector system with fiberoptic readout that measures the urethral dose during high-dose-rate brachytherapy treatment of the prostate. Methods and Materials: The clinical trial enrolled 24 patients receiving high-dose-rate brachytherapy treatment to the prostate. After the first 14 patients, three improvements were made to the dosimeter system design to improve clinical reliability: a dosimeter self-checking facility; a radiopaque marker to determine the position of the dosimeter, and a more robust optical extension fiber. Results: Improvements to the system design allowed for accurate dose measurements to be made in vivo. A maximum measured dose departure of 9% from the calculated dose was observed after dosimeter design improvements. Conclusions: Departures of the measured from the calculated dose, after improvements to the dosimetry system, arise primarily from small changes in patient anatomy. Therefore, we recommend that patient response be correlated with the measured in vivo dose rather than with the calculated dose.

Suchowerska, Natalka, E-mail: natalka@email.cs.nsw.gov.a [Radiation Oncology, Royal Prince Alfred Hospital, New South Wales (Australia); School of Physics, University of Sydney, New South Wales (Australia); Jackson, Michael [Radiation Oncology, Prince of Wales Hospital, New South Wales (Australia); Department of Medicine, University of Sydney, New South Wales (Australia); Lambert, Jamil; Yin, Yong Bai [School of Physics, University of Sydney, New South Wales (Australia); Hruby, George [Radiation Oncology, Royal Prince Alfred Hospital, New South Wales (Australia); Department of Medicine, University of Sydney, New South Wales (Australia); McKenzie, David R. [School of Physics, University of Sydney, New South Wales (Australia)

2011-02-01

313

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

314

Improvements in Calibration of GSO Scintillators in the Suzaku Hard X-Ray Detector  

NASA Astrophysics Data System (ADS)

Improvements of the in-orbit calibration of GSO scintillators in the Hard X-ray Detector aboard Suzaku are reported. To resolve an apparent change in the energy scale of GSO, which appeared across the launch for unknown reasons, consistent and thorough re-analyses of both pre-launch and in-orbit data have been performed. With laboratory experiments using spare hardware, the pulse-height offset, corresponding to zero energy input, was found to change by ˜ 0.5% of the full analog voltage scale, depending on the power supply. Furthermore, by carefully calculating all of the light outputs of secondaries from activation lines used in the in-orbit gain determination, their energy deposits in GSO were found to be effectively lower, by several percent, than their nominal energies. Taking both of these effects into account, the in-orbit data agree with the on-ground measurements within ˜ 5%, without employing the artificial correction introduced in previous work (Kokubun et al. 2007, PASJ, 59, S53). With this knowledge, we updated the data processing, the response, and the auxiliary files of GSO, and reproduced the HXD-PIN and HXD-GSO spectra of the Crab Nebula over 12-300 keV by a broken power-law with a break energy of ˜ 110 keV.

Yamada, Shin'ya; Makishima, Kazuo; Nakazawa, Kazuhiro; Kokubun, Motohide; Kawaharada, Madoka; Kitaguchi, Takao; Watanabe, Shin; Takahashi, Hiromitsu; Noda, Hirofumi; Nishioka, Hiroyuki; Hiragi, Kazuyoshi; Hayashi, Katsuhiro; Nakajima, Kenta; Tashiro, Makoto; Sasano, Makoto; Nishino, Sho; Torii, Shunsuke; Sakurai, Soki; Takahashi, Tadayuki; Mizuno, Tsunefumi; Enoto, Teruaki; Yuasa, Takayuki; Tanaka, Takaaki; Kouzu, Tomomi; Nakano, Toshio; Fukazawa, Yasushi; Terada, Yukikatsu; Uchiyama, Yasunobu; Iwakiri, Wataru

2011-11-01

315

Study of scintillation in helium mixed with xenon to develop thermal neutron detectors  

Microsoft Academic Search

We have studied the transfer of luminescence from He to Xe by adding a small amount of Xe to He. Luminescence spectra, scintillation yields and time profiles of the mixture were measured. The He\\/Xe mixture emitted scintillation photons in the 140–210nm wavelength region, peaked around 173nm. The scintillation yields and time profiles were measured using a PMT sensitive to photon

Kiwamu Saito; Shinichi Sasaki; Hiroko Tawara; Toshiya Sanami; Eido Shibamura

2007-01-01

316

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

317

Data-Driven Exploration of the Ionization-Phonon Partitioning in Scintillating Radiation Detector Materials  

Microsoft Academic Search

An information-based approach to scintillating materials development has been applied to ranking the alkali halide and alkaline earth halide series in terms of their energy conversion efficiency. The efficiency of scintillating radiation detection materials can be viewed as the product of a consecutive series of electronic processes (energy conversion, transfer, and luminescence) as outlined by Lempicki and others. Relevant data

Kim F. Ferris; Bobbie-Jo M. Webb-Robertson; David V. Jordan; Dumont M. Jones

2008-01-01

318

A fast UV-LED QRdriver for calibration system for SiPM based scintillator HCAL detector  

NASA Astrophysics Data System (ADS)

We report on latest version of the calibration and monitoring system developed for the scintillator tile hadron calorimeter (AHCAL) for the ILC. System is based on original fast (3.5 ns pulse width) and precise LED driver board called QMB. One UV-LED can illuminate 72 scintillating tiles with SiPM. Distribution of the light pulses uses notched fibres, developed at our laboratory. All parts of the system are continually upgraded to get better results. The system is flexible to all necessary monitoring and calibration of SiPM detector tasks. It has high dynamic range of precise a few nanosecond pulses. Low intensity LED pulses are needed to obtain SiPM single photoelectron spectra. A routine monitoring of all SiPMs during the test beam operations is achieved with mid-range a fixed-intensity light pulse. The full SiPM response function is cross-checked by varying the light intensity from zero to the saturation level. In calibration systems we developed, we concentrate especially on the aspect a high dynamic range of precise a few nanosecond pulses. Calibration system has been tested with 2.2 m long slab of engineering AHCAL prototype, which uses 864 SiPM embedded in 3 by 3 cm scintillator tiles and represents a part of the biggest foreseen detector using SiPMs.

Polák, I.; Kvasni?ka, J.

2014-03-01

319

Validating plastic scintillation detectors for photon dosimetry in the radiologic energy range  

SciTech Connect

Purpose: Photon dosimetry in the kilovolt (kV) energy range represents a major challenge for diagnostic and interventional radiology and superficial therapy. Plastic scintillation detectors (PSDs) are potentially good candidates for this task. This study proposes a simple way to obtain accurate correction factors to compensate for the response of PSDs to photon energies between 80 and 150 kVp. The performance of PSDs is also investigated to determine their potential usefulness in the diagnostic energy range. Methods: A 1-mm-diameter, 10-mm-long PSD was irradiated by a Therapax SXT 150 unit using five different beam qualities made of tube potentials ranging from 80 to 150 kVp and filtration thickness ranging from 0.8 to 0.2 mmAl + 1.0 mmCu. The light emitted by the detector was collected using an 8-m-long optical fiber and a polychromatic photodiode, which converted the scintillation photons to an electrical current. The PSD response was compared with the reference free air dose rate measured with a calibrated Farmer NE2571 ionization chamber. PSD measurements were corrected using spectra-weighted corrections, accounting for mass energy-absorption coefficient differences between the sensitive volumes of the ionization chamber and the PSD, as suggested by large cavity theory (LCT). Beam spectra were obtained from x-ray simulation software and validated experimentally using a CdTe spectrometer. Correction factors were also obtained using Monte Carlo (MC) simulations. Percent depth dose (PDD) measurements were compensated for beam hardening using the LCT correction method. These PDD measurements were compared with uncorrected PSD data, PDD measurements obtained using Gafchromic films, Monte Carlo simulations, and previous data. Results: For each beam quality used, the authors observed an increase of the energy response with effective energy when no correction was applied to the PSD response. Using the LCT correction, the PSD response was almost energy independent, with a residual 2.1% coefficient of variation (COV) over the 80-150-kVp energy range. Monte Carlo corrections reduced the COV to 1.4% over this energy range. All PDD measurements were in good agreement with one another except for the uncorrected PSD data, in which an over-response was observed with depth (13% at 10 cm with a 100 kVp beam), showing that beam hardening had a non-negligible effect on the PSD response. A correction based on LCT compensated very well for this effect, reducing the over-response to 3%.Conclusion: In the diagnostic energy range, PSDs show high-energy dependence, which can be corrected using spectra-weighted mass energy-absorption coefficients, showing no considerable sign of quenching between these energies. Correction factors obtained by Monte Carlo simulations confirm that the approximations made by LCT corrections are valid. Thus, PSDs could be useful for real-time dosimetry in radiology applications.

Lessard, Francois; Archambault, Louis; Plamondon, Mathieu [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 physique, de genie physique et d'optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada); Departement de radio-oncologie, Hotel-Dieu de Quebec, Centre hospitalier universitaire de Quebec, Quebec G1R 2J6 (Canada) and Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Department of Radiation Physics, University of Texas MD Anderson Cancer Center, 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); and others

2012-09-15

320

Effect of x-ray incident direction and scintillator layer design on image quality of indirect-conversion flat-panel detector with GOS phosphor  

NASA Astrophysics Data System (ADS)

In this study, we characterized the image quality of two types of indirect-conversion flat-panel detectors: an X-ray incident-side photo-detection system (IS) and an X-ray penetration-side photo-detection system (PS). These detectors consist of a Gd2O2S:Tb (GOS) scintillator coupled with a photodiode thin film transistor (PD-TFT) array on a glass substrate. The detectors have different X-ray incident directions, glass substrates, and scintillators. We also characterized the effects of layered scintillator structures on the image quality by using a single-layered scintillator containing large phosphor grains and a double-layered scintillator consisting of a layer of large phosphor grains and a layer of small phosphor grains. The IS system consistently demonstrated a higher MTF than the PS system for a scintillator of the same thickness. Moreover, the IS system showed a higher DQE than the PS system when a thick scintillator was used. While the double-layered scintillators were useful for improving the MTF in both systems, a thick single-layered scintillator was preferable for obtaining a high DQE when the IS system was applied. These results indicate that an IS system can efficiently utilize the light emitted from the phosphor at the far side of the PD without the occurrence of blurring. The use of IS systems makes it possible to increase the thickness of the scintillator layer for improving the sensitivity without reducing the MTF, which increases the DQE. The DQE of the IS system was 1.2 times that of the PS system, despite the absorption of X-rays at the glass substrate before entering the phosphor.

Sato, K.; Nariyuki, F.; Nomura, H.; Takasu, A.; Fukui, S.; Nakatsu, M.; Okada, Y.; Nabeta, T.; Hosoi, Y.

2011-03-01

321

Investigation of the influence of an inner gas bubble on the response of a liquid scintillation detector to ?-rays and neutrons  

NASA Astrophysics Data System (ADS)

The influence of an inert gas bubble inside EJ301 cylindrical cell on the response of the liquid scintillation detector to ?-rays and neutrons has been investigated. It is found experimentally that the response of the detector to radiation varies with the detector placement styles. The explanation proposed in this article is that this variation arises from the change of the light transmission process induced by the motion of the inner gas bubble. This assertion has been supported by the simulations of both radiation energy deposition and light transmission process inside the detector with the GEANT4 code. For the recommended detector placement style when the detector is placed horizontally, the variation of the response is smaller than 1.56%, which will increase to about 22% when the detector is placed facing down and the bubble lies between the scintillator and photomultiplier tube.

Xufei, Xie; Xing, Zhang; Xi, Yuan; Tieshuan, Fan; Jinxiang, Chen; Xiangqing, Li

2013-09-01

322

SHIELDING AND DETECTOR RESPONSE CALCULATIONS PERTAINING TO CATEGORY 1 QUANTITIES OF PLUTONIUM AND HAND-HELD PLASTIC SCINTILLATORS  

SciTech Connect

Nuclear facilities sometimes use hand-held plastic scintillator detectors to detect attempts to divert special nuclear material in situations where portal monitors are impractical. MCNP calculations have been performed to determine the neutron and gamma radiation field arising from a Category I quantity of weapons-grade plutonium in various shielding configurations. The shields considered were composed of combinations of lead and high-density polyethylene such that the mass of the plutonium plus shield was 22.7 kilograms. Monte-Carlo techniques were also used to determine the detector response to each of the shielding configurations. The detector response calculations were verified using field measurements of high-, medium-, and low- energy gamma-ray sources as well as a Cf-252 neutron source.

Couture, A.

2013-06-07

323

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

324

Laser and beta source setup characterization of 3D-DDTC detectors fabricated at FBK-irst  

Microsoft Academic Search

We report on the functional characterization of the first batch of 3D Double-Sided Double Type Column (3D-DDTC) detectors fabricated at FBK, Trento. This detector concept represents the evolution of the previous 3D-STC detectors towards full 3D detectors, and is expected to achieve a performance which is comparable to standard 3D detectors, but with a simpler fabrication process. Measurements were performed

A. Zoboli; G.-F. Dalla Betta; M. Boscardin; L. Bosisio; S. Eckert; S. Kühn; U. Parzefall; C. Piemonte; S. Ronchin; N. Zorzi

2009-01-01

325

Dual Scintillator with Pulse Shaping Electronics as a Wide-Energy Range Neutron Detector.  

National Technical Information Service (NTIS)

Because of continued concern and need for improved neutron monitoring and surveillance around nuclear facilities and weapons, where the possibility of fission excursions exists, we are investigating several neutron-sensitive scintillators and combinations...

M. M. Chiles S. A. McElhaney R. A. Todd

1988-01-01

326

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

PubMed

In block detectors for PET scanners that use different lengths of slits in scintillators to share light among photomultiplier tubes (PMTs), a position histogram is distorted when the depth of interaction (DOI) of the gamma photons is near the PMTs (DOI effect). However, it remains unclear whether a DOI effect is observed for block detectors that use light sharing in scintillators. To investigate the effect, I tested the effect for single- and dual-layer block detectors. In the single-layer block detector, Ce doped Gd?SiO? (GSO) crystals of 1.9 × 1.9 × 15 mm³ (0.5 mol% Ce) were used. In the dual-layer block detector, GSO crystals of a 1.9 × 1.9 × 6 mm³ (1.5 mol% Ce) were used for the front layer and GSO crystals of 1.9 × 1.9 × 9 mm³ (0.5 mol% Ce) for the back layer. These scintillators were arranged to form an 8 × 8 matrix with multi-layer optical film inserted partly between the scintillators for obtaining an optimized position response with use of two dual-PMTs. Position histograms and energy responses were measured for these block detectors at three different DOI positions, and the flood histograms were obtained. The results indicated that DOI effects are observed in both block detectors, but the dual-layer block showed more severe distortion in the position histogram as well as larger energy variations. We conclude that, in the block detectors that use light sharing in the scintillators, the DOI effect is an important factor for the performance of the detectors, especially for DOI block detectors. PMID:21927889

Yamamoto, Seiichi

2012-01-01

327

A scintillator-based online detector for the angularly resolved measurement of laser-accelerated proton spectra  

SciTech Connect

In recent years, a new generation of high repetition rate ({approx}10 Hz), high power ({approx}100 TW) laser systems has stimulated intense research on laser-driven sources for fast protons. Considering experimental instrumentation, this development requires online diagnostics for protons to be added to the established offline detection tools such as solid state track detectors or radiochromic films. In this article, we present the design and characterization of a scintillator-based online detector that gives access to the angularly resolved proton distribution along one spatial dimension and resolves 10 different proton energy ranges. Conceived as an online detector for key parameters in laser-proton acceleration, such as the maximum proton energy and the angular distribution, the detector features a spatial resolution of {approx}1.3 mm and a spectral resolution better than 1.5 MeV for a maximum proton energy above 12 MeV in the current design. Regarding its areas of application, we consider the detector a useful complement to radiochromic films and Thomson parabola spectrometers, capable to give immediate feedback on the experimental performance. The detector was characterized at an electrostatic Van de Graaff tandetron accelerator and tested in a laser-proton acceleration experiment, proving its suitability as a diagnostic device for laser-accelerated protons.

Metzkes, J.; Kraft, S. D.; Sobiella, M.; Stiller, N.; Zeil, K.; Schramm, U. [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany); Karsch, L.; Schuerer, M. [OncoRay - National Center for Radiation Research in Oncology, TU Dresden, Fetscherstr. 74, 01307 Dresden (Germany); Pawelke, J.; Richter, C. [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany); OncoRay - National Center for Radiation Research in Oncology, TU Dresden, Fetscherstr. 74, 01307 Dresden (Germany)

2012-12-15

328

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

329

A position-sensitive scintillation detector for two-dimensional angular correlation of annihilation radiation using metal-package position-sensitive photomultiplier tubes  

Microsoft Academic Search

We have constructed and tested a prototype of a new position sensitive ?-ray detector which consists of an array of 2.6×2.6×18mm3 BGO scintillator blocks, a light guide, and four metal-package position-sensitive photomultiplier tubes (R5900-00-C8) recently developed by Hamamatsu Photonics Co. Ltd. Scalability of the detector of this type makes it possible to construct a larger detector using many PS-PMTs, which

Koji Inoue; Yasuyoshi Nagai; Haruo Saito; Yasuyuki Nagashima; Toshio Hyodo; Shinichi Muramatsu; Shota Nagai

1999-01-01

330

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

SciTech Connect

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 {approx}2% of the incident radiation, thus severely limiting their imaging performance as quantified by the detective quantum efficiency (DQE) ({approx}1%, compared to {approx}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 {approx}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.

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 [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48105 (United States); Imaging Research Laboratories, Robarts Research Institute, London, Ontario N6A 5C1 (Canada); Radiation Monitoring Devices, Watertown, Massachusetts 02472 (United States)

2005-10-15

331

Resarch investigation on dense scintillation glass for use in total absorption nuclear cascade detectors  

NASA Technical Reports Server (NTRS)

Three approaches to the development of a high density scintillation glass were investigated: They include the increase of density of glass systems containing cerium - the only systems which were known to show scintillation, the testing of a novel silicate glass system containing significant concentrations of silver produced by ion exchange and never tested previously, and the hot pressing of a diphasic compact of low density scintillation glass with high density passive glass. In first two cases, while ultraviolet excited fluorescence was maintained in the glasses showing high density, scintillation response to high energy particles was not retained in the case of the cerium containing glasses or developed in the case of the silver containing glasses. In the case of the compacts, the extremely long path length caused by the multiple internal reflections which occur in such a body resulted in attenuation even with glasses of high specific transmission. It is not clear why the scintillation efficiency is not maintained in the higher density cerium containing glasses.

Hensler, J. R.

1973-01-01

332

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

333

Determination of the specific alpha activity of thick sources with a large area ZnS(Ag) scintillation detector.  

PubMed

A method for determining the specific alpha activity of thick sources using a large area ZnS(Ag) scintillation detector is presented. In this method a quadratic relationship between the detector response and window thickness is assumed. This method provides a quick estimation of alpha activity in the sample, so it is an indicative method. The aim of this experimental work is to approve theoretical assumption and to develop a standard routine method for absolute alpha measurements of thick contaminated environmental sources. For this purpose reference material U(3)O(8) and spiked standards of soil were used. Measurements of contaminated soil samples from south Serbia showed the practical application of this method. PMID:17383779

Djurasevi?, M; Vukanac, I; Kandi?, A; Nadderd, L; Milosevi?, Z; Radenkovi?, M

2007-01-01

334

Development of InP solid state detector and liquid scintillator containing metal complex for measurement of pp/7Be solar neutrinos and neutrinoless double beta decay  

NASA Astrophysics Data System (ADS)

A large volume solid state detector using a semi-insulating Indium Phosphide (InP) wafer have been developed for measurement of pp/7Be solar neutrinos. Basic performance such as the charge collection efficiency and the energy resolution were measured by 60% and 20%, respectively. In order to detect two gammas (115keV and 497keV) from neutrino capture, we have designed hybrid detector which consist InP detector and liquid xenon scintillator for IPNOS experiment. New InP detector with thin electrode (Cr 50Å- Au 50Å). For another possibility, an organic liquid scintillator containing indium complex and zirconium complex were studied for a measurement of low energy solar neutrinos and neutrinosless double beta decay, respectively. Benzonitrile was chosen as a solvent because of good solubility for the quinolinolato complexes (2 wt%) and of good light yield for the scintillation induced by gamma-ray irradiation. The photo-luminescence emission spectra of InQ3 and ZrQ4 in benzonitrile was measured and liquid scintillator cocktail using InQ3 and ZrQ4 (50mg) in benzonitrile solutions (20 mL) with secondary scintillators with PPO (100mg) and POPOP (10mg) was made. The energy spectra of incident gammas were measured, and they are first results of the gamma-ray energy spectra using luminescent of metal complexes.

Fukuda, Yoshiyuki; Moriyama, Shigetaka

2012-07-01

335

Performance of a phoswich detector composed of an inner NaI(Tl) crystal and surrounding NE102A plastic scintillator for neutron spectrometry  

NASA Astrophysics Data System (ADS)

We have developed a phoswich detector for neutron spectrometry, which adopts a reversed configuration of slow- and fast-decay-time scintillators in its inner and surrounding outer regions, respectively, in the detection of recoil protons from a hydrogenous radiator. The phoswich detector consists of an inner slow, NaI(Tl) scintillator, and an outer fast, plastic scintillator. This configuration allows us to discriminate protons of full kinetic-energy deposition only in the NaI(Tl) scintillator and those not stopping in the inner scintillator. The response functions of the phoswich detector were measured for neutron energies ranging from 100 to 350 MeV. The experiment used the recoil-proton method and pulse-shape discrimination with the two-gate integration technique using a spallation neutron source at the WNR facility of the Los Alamos Neutron Science Center (LANSCE). The experimental results were consistent with calculations by the Particle and Heavy Ion Transport code System (PHITS). To evaluate the effectiveness of the phoswich configuration, full energy-deposition fraction was calculated. This fraction is defined as the ratio of the integration around the full-energy peak to that of the entire energy region. The calculation confirmed that the phoswich detector with a reversed configuration is useful for neutron measurements.

Watanabe, T.; Arakawa, H.; Kajimoto, T.; Iwamoto, Y.; Satoh, D.; Kunieda, S.; Noda, S.; Shigyo, N.; Ishibashi, K.; Nakamura, T.; Haight, R. C.

2008-03-01

336

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

337

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

338

Calibration of scintillation detectors for MeV charged fusion products  

SciTech Connect

The light output of ZnS scintillators used to detect escaping fusion products in the TFTR Tokamak is studied with 3.5 MeV alpha and 3 MeV proton beams. The emitted light first increases linearly with beam current and then saturates. In all cases investigated, the onset of the saturation corresponds to a power of about 1 mW absorbed within the ZnS powder. The scintillators have adequate time response up to 50--100 kHz.

Tuszewski, M. [Los Alamos National Lab., NM (United States); Zweben, S.J. [Princeton Univ., NJ (United States). Plasma Physics Lab.

1991-12-31

339

Calibration of scintillation detectors for MeV charged fusion products  

SciTech Connect

The light output of ZnS scintillators used to detect escaping fusion products in the TFTR Tokamak is studied with 3.5 MeV alpha and 3 MeV proton beams. The emitted light first increases linearly with beam current and then saturates. In all cases investigated, the onset of the saturation corresponds to a power of about 1 mW absorbed within the ZnS powder. The scintillators have adequate time response up to 50--100 kHz.

Tuszewski, M. (Los Alamos National Lab., NM (United States)); Zweben, S.J. (Princeton Univ., NJ (United States). Plasma Physics Lab.)

1991-01-01

340

Calibration of scintillation detectors for MeV charged fusion products  

SciTech Connect

The light output of ZnS scintillators used to detect escaping fusion products in the TFTR Tokamak is studied with 3.5-MeV alpha and 3-MeV proton beams. The emitted light first increases linearly with beam current and then saturates. In all cases investigated, the saturations start at a fairly constant absorbed power density of about 1 mW/cm{sup 2}. The scintillators have adequate time response up to 50--100 kHz.

Tuszewski, M. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)); Zweben, S.J. (Princeton Plasma Physics Laboratory, Princeton, New Jersey 08544 (United States))

1992-10-01

341

The scintillating fiber detectors of the H1 forward proton spectrometer  

SciTech Connect

Since 1995 the H1 experiment at HERA is operating a Forward Proton Spectrometer (FPS) employing the HERA machine magnets adjacent to the interaction zone as spectrometer magnets. The FPS consists of four stations, two vertical stations and two horizontal stations. Scattered protons are detected in pairs of stations behind the interaction point with scintillating fiber hodoscopes. The scintillating fibers are readout by Position-Sensitive Photomultipliers (PSPM) in the case of the vertical stations and by Micro-Channel Photomultipliers (MCPM) for the horizontal stations.

Baehr, J.; Harder, U.; Hiller, K.; Luedecke, H.; Nahnhauer, R. [DESY-Zeuthen, 15738 Zeuthen (Germany)

1998-11-09

342

Spectral response of CsI(Tl) transparent scintillation detector for megavoltage imaging  

NASA Astrophysics Data System (ADS)

In megavoltage imaging, current commercial electronic portal imaging devices (EPIDs), despite having the advantage of immediate digital imaging over film, suffer from poor image contrast and spatial resolution. In a previous paper, a prototype megavoltage portal imaging system was described that utilized a 3 mm thick 100 mm field of view CsI (Tl) transparent scintillating crystal (corresponding to a radiological thickness of 1350 mg/cm2) coupled to a liquid nitrogen cooled slow-scan CCD camera with a combination of two camera lenses to yield a 42 mm f1.0 macro lens and a 5:1 demagnification. The imaging display significantly superior contrast and spatial resolutions (1 lp/mm at 20% MTF) to that available from the commercial EPIDs, which typically consist of a CCD camera coupled to a relatively thin gadolinium oxysulfide screen (with a radiological thickness of 400 mg/cm2). However it required significantly higher dose than portal film. Subsequent effort has focused on optimization of the optics and scintillator thickness in order to reduce the required imaging dose, while still providing superior image and contrast resolutions to that of the commercial EPIDs. Improved images were acquired using a two- camera lens combination yielding a 50 mm f1.1 macro lens with a 7:1 demagnification. Subsequently, portal imaging with an even thicker 13 mm CsI(Tl) scintillator (corresponding to a radiological thickness of 5850 mg/cm2) was carried out. An increase in scintillator thickness was accompanied by only a small loss in spatial resolution (1 lp/mm at 17% MTF) by optimizing the optical geometry. The image quality was significantly superior to that of the commercial EPIDs (Elekta SRI-100 and Siemens BEAMVIEW), and comparable to that for portal film, while requiring an imaging dose that was less than or comparable to that for film or the EPIDs. The purpose of this research is to investigate the effect of spectral shifting and buildup material or imaging for this prototype system. The use of clear thick single crystal scintillators is relatively new in portal imaging. Early work on optimization of CCD based EPIDs dealt primarily with amorphous nontransparent scintillators, and the use of thick scintillators was abandoned due to a clinically unacceptable associated loss in spatial resolution. Optimization of CCD based EPIDs has been implicitly based on the use of thin scintillators. This recent imaging success of the CsI(Tl) scintillator CCD camera based system utilizing a relatively thick scintillator offers a possibly superior alternative to the current CCD based systems. This superior imaging was accomplished in the absence of any optimization dealing with the choice of buildup material or thickness. Such optimization presents the potential for further gains in imaging quality. Experimental results dealing with optimization of scintillator thickness and buildup plate thickness and material are presented. The effect on image quality due to a spectral shift in a 6 MV photon beam in the presence of phantom scatter is discussed.

Samant, Sanjiv S.; Zeman, Herbert D.; Weinberg, Brent D.; Zheng, Wei; Patra, Pradeep K.

1999-05-01

343

ATLAS ALFA—measuring absolute luminosity with scintillating fibres  

NASA Astrophysics Data System (ADS)

ALFA is a high-precision scintillating fibre tracking detector under construction for the absolute determination of the LHC luminosity at the ATLAS interaction point. This detector, mounted in so-called Roman Pots, will track protons elastically scattered under ?rad angles at IP1.In total there are four pairs of vertically arranged detector modules which approach the LHC beam axis to mm distance. Each detector module consists of ten layers of two times 64 scintillating fibres each (U and V planes). The fibres are coupled to 64 channels Multi-Anodes PhotoMultipliers Tubes read out by compact front-end electronics. Each detector module is complemented by so-called overlap detectors: Three layers of two times 30 scintillating fibres which will be used to measure the relative positioning of two vertically arranged main detectors. The total number of channels is about 15000. Conventional plastic scintillator tiles are mounted in front of the fibre detectors and will serve as trigger counter. The extremely restricted space inside the pots makes the coupling to the read out devices very challenging. Several technologies have been tested in a beam at DESY and a cosmic-ray setup at CERN. A possible upgrade of the photo detection could consist in the replacement of the PMT by Geiger-mode avalanche photodiodes. Preliminary tests are being performed comparing the performance of these devices with the ones of the PMTs.

Franz, S.; Barrillon, P.

2009-10-01

344

In vivo gamma measurements at very low levels with 4? liquid scintillation detectors  

Microsoft Academic Search

A large 4? liquid scintillation counter for the rapid measurement of total internal gamma contamination of the human body at concentrations 1000 times less than the maximum permissible levels is described. A counting time of only 100 seconds per subject is required to obtain a sensitivity of 5 ?? 10-10 curies for 1.5 mev gamma rays. Because of the high

Ernest C. Anderson

1956-01-01

345

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

346

Spectral response of CsI(Tl) transparent scintillation detector for megavoltage imaging  

Microsoft Academic Search

In megavoltage imaging, current commercial electronic portal imaging devices (EPIDs), despite having the advantage of immediate digital imaging over film, suffer from poor image contrast and spatial resolution. In a previous paper, a prototype megavoltage portal imaging system was described that utilized a 3 mm thick 100 mm field of view CsI (Tl) transparent scintillating crystal (corresponding to a radiological

Sanjiv S. Samant; Herbert D. Zeman; Brent D. Weinberg; Wei Zheng; Pradeep K. Patra

1999-01-01

347

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

348

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

349

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

350

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

351

Plastic scintillation dosimetry: optimal selection of scintillating fibers and scintillators.  

PubMed

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. PMID:16121582

Archambault, Louis; Arsenault, Jean; Gingras, Luc; Beddar, A Sam; Roy, René; Beaulieu, Luc

2005-07-01

352

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

353

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

354

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

355

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

Microsoft Academic Search

In this research, we report the results of neutron-gamma 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 gamma-ray detection, were used to detect neutrons and gamma-rays from a PuBe source enclosed in paraffin. Following digitization

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

2011-01-01

356

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

Microsoft Academic Search

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 ?-rays from a 137Cs source was obtained with a 9 mm in diameter by 9 mm high CsI(Tl) scintillator coupled to

M. Moszynski; M. Kapusta; D. Wolski; M. Szawlowski; W. Klamra

1998-01-01

357

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

SciTech Connect

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.

Shen, Youtao; Zhong, Yuncheng; Lai, Chao-Jen; Wang, Tianpeng; Shaw, Chris C. [Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030 (United States)] [Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030 (United States)

2013-10-15

358

Real-time, digital pulse-shape discrimination in non-hazardous fast liquid scintillation detectors: Prospects for safety and security  

Microsoft Academic Search

Pulse-shape discrimination (PSD) in fast, organic scintillation detectors is a long-established technique used to separate neutrons and ? rays in mixed radiation fields. In the analogue domain the method can achieve separation in real time, but all knowledge of the pulses themselves is lost thereby preventing the possibility of any post- or repeated analysis. Also, it is typically reliant on

Malcolm J. Joyce; Michael D. Aspinall; Francis D. Cave; Anthony D. Lavietes

2011-01-01

359

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

1997-01-01

360

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

361

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. 3 figures.

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

1991-05-14

362

Preliminary evaluation of the dosimetric accuracy of the in vivo plastic scintillation detector OARtrac system for prostate cancer treatments.  

PubMed

A promising, new, in vivo prostate dosimetry system has been developed for clinical radiation therapy. This work outlines the preliminary end-to-end testing of the accuracy and precision of the new OARtrac scintillation dosimetry system. We tested 94 calibrated plastic scintillation detector (PSD) probes before their final integration into endorectal balloon assemblies. These probes had been calibrated at The University of Texas MD Anderson Cancer Center Dosimetry Laboratory. We used a complete clinical OARtrac system including the PSD probes, charge coupled device camera monitoring system, and the manufacturer's integrated software package. The PSD probes were irradiated at 6 MV in a Solid Water® phantom. Irradiations were performed with a 6 MV linear accelerator using anterior-posterior/posterior-anterior matched fields to a maximum dose of 200 cGy in a 100 cm source-axis distance geometry. As a whole, the OARtrac system has good accuracy with a mean error of 0.01% and an error spread of ±5.4% at the 95% confidence interval. These results reflect the PSD probes' accuracy before their final insertion into endorectal balloons. Future work will test the dosimetric effects of mounting the PSD probes within the endorectal balloon assemblies. PMID:24732073

Klawikowski, Slade J; Zeringue, Clint; Wootton, Landon S; Ibbott, Geoffrey S; Beddar, Sam

2014-05-01

363

Preliminary evaluation of the dosimetric accuracy of the in vivo plastic scintillation detector OARtrac system for prostate cancer treatments  

NASA Astrophysics Data System (ADS)

A promising, new, in vivo prostate dosimetry system has been developed for clinical radiation therapy. This work outlines the preliminary end-to-end testing of the accuracy and precision of the new OARtrac scintillation dosimetry system. We tested 94 calibrated plastic scintillation detector (PSD) probes before their final integration into endorectal balloon assemblies. These probes had been calibrated at The University of Texas MD Anderson Cancer Center Dosimetry Laboratory. We used a complete clinical OARtrac system including the PSD probes, charge coupled device camera monitoring system, and the manufacturer's integrated software package. The PSD probes were irradiated at 6 MV in a Solid Water® phantom. Irradiations were performed with a 6 MV linear accelerator using anterior–posterior/posterior–anterior matched fields to a maximum dose of 200 cGy in a 100 cm source-axis distance geometry. As a whole, the OARtrac system has good accuracy with a mean error of 0.01% and an error spread of ±5.4% at the 95% confidence interval. These results reflect the PSD probes’ accuracy before their final insertion into endorectal balloons. Future work will test the dosimetric effects of mounting the PSD probes within the endorectal balloon assemblies.

Klawikowski, Slade J.; Zeringue, Clint; Wootton, Landon S.; Ibbott, Geoffrey S.; Beddar, Sam

2014-05-01

364

Digital discrimination of neutron and ? ray using an organic scintillation detector based on wavelet transform modulus maximum  

NASA Astrophysics Data System (ADS)

A novel algorithm for the discrimination of neutron and ?-ray events with wavelet transform modulus maximum (WTMM) in an organic scintillation has been investigated. Voltage pulses arising from a BC501A organic liquid scintillation detector in a mixed radiation field have been recorded with a fast digital sampling oscilloscope. The WTMM method using frequency-domain features exhibits a strong insensitivity to noise and can be used to discriminate neutron and ?-ray events based on their different asymptotic decay trend between the positive modulus maximum curve and the negative modulus maximum curve in the scale-space plane. This technique has been verified by the corresponding mixed-field data assessed by the time-of-flight (TOF) method and the charge comparison (CC) method. It is shown that the characterization of neutron and ? ray achieved by the discrimination method based on WTMM is consistent with that afforded by the TOF method and better than the CC method. Moreover, the WTMM method itself has presented its ability to eliminate the noise without any pretreatment to the pulses.

Yang, Yun; Liu, Guo-Fu; Yang, Jun; Luo, Xiao-Liang; Meng, De-Yuan

2014-03-01

365

Theoretical response of a ZnS(Ag) scintillation detector to alpha-emitting sources and suggested applications  

SciTech Connect

The classic problem of alpha absorption is discussed in terms of the quantitative determination of the activity of weightless alpha sources and the specific alpha activity of extended sources accounting for absorption in the source medium and the window of a large area ZnS(Ag) scintillation detector. The relationship for the expected counting rate gamma of a monoenergetic source of active area A, specific alpha activity C, and thickness H that exceeds the effective mass density range Rs of the alpha particle in the source medium can be expressed by a quadratic equation in the window thickness x when this source is placed in direct contact with the window of the ZnS(Ag) detector. This expression also gives the expected counting rate of a finite detector of sensitive area A exposed to an infinite homogeneous source medium. Counting rates y obtained for a source separated from a ZnS(Ag) detector by different thicknesses x of window material can be used to estimate parameter values in the quadratic equation, y = a + bx + cx2. The experimental value determined for the coefficient b provides a direct estimation of the specific activity C. This coefficient, which depends on the ratio of the ranges in the source medium and detector window and not the ranges themselves, is essentially independent of the energy of the alpha particle. Although certain experimental precautions must be taken, this method for estimating the specific activity C is essentially an absolute method that does not require the use of standards, special calibrations, or complicated radiochemical procedures. Applications include the quantitative determination of Rn and progeny in air, water, and charcoal, and the measurement of the alpha activity in soil and on air filter samples.

Skrable, K.W.; Phoenix, K.A.; Chabot, G.E.; French, C.S.; Jo, M.; Falo, G.A. (Univ. of Lowell, MA (USA))

1991-03-01

366

Theoretical response of a ZnS(Ag) scintillation detector to alpha-emitting sources and suggested applications.  

PubMed

The classic problem of alpha absorption is discussed in terms of the quantitative determination of the activity of "weightless" alpha sources and the specific alpha activity of extended sources accounting for absorption in the source medium and the window of a large area ZnS(Ag) scintillation detector. The relationship for the expected counting rate gamma of a monoenergetic source of active area A, specific alpha activity C, and thickness H that exceeds the effective mass density range Rs of the alpha particle in the source medium can be expressed by a quadratic equation in the window thickness x when this source is placed in direct contact with the window of the ZnS(Ag) detector. This expression also gives the expected counting rate of a finite detector of sensitive area A exposed to an infinite homogeneous source medium. Counting rates y obtained for a source separated from a ZnS(Ag) detector by different thicknesses x of window material can be used to estimate parameter values in the quadratic equation, y = a + bx + cx2. The experimental value determined for the coefficient b provides a direct estimation of the specific activity C. This coefficient, which depends on the ratio of the ranges in the source medium and detector window and not the ranges themselves, is essentially independent of the energy of the alpha particle. Although certain experimental precautions must be taken, this method for estimating the specific activity C is essentially an absolute method that does not require the use of standards, special calibrations, or complicated radiochemical procedures. Applications include the quantitative determination of Rn and progeny in air, water, and charcoal, and the measurement of the alpha activity in soil and on air filter samples. PMID:1995511

Skrable, K W; Phoenix, K A; Chabot, G E; French, C S; Jo, M; Falo, G A

1991-03-01

367

Shaped scintillation detector systems for measurements of gamma ray flux anisotropy  

NASA Technical Reports Server (NTRS)

The detection efficiencies of cylindrical detectors for various gamma ray photon angular distributions were studied in the energy range from .10 Mev to 15 Mev. These studies indicate that simple detector systems on small satellites can be used to measure flux anisotropy of cosmic gamma rays and the angular distribution of albedo gamma rays produced in planetary atmospheres. The results indicate that flat cylindrical detectors are most suitable for measuring flux anisotropy because of their angular response function. A general method for calculating detection efficiencies for such detectors is presented.

Trombka, J. I.; Vette, J. I.; Stecker, F. W.; Eller, E. L.; Wildes, W. T.

1973-01-01

368

Implementation of gamma-ray spectrometry in two real-time water monitors using NaI(Tl) scintillation detectors.  

PubMed

In this study, the implementation of gamma-ray spectrometry in two real-time water monitors using 2 in. × 2 in. NaI(Tl) scintillation detectors is described. These monitors collect the water from the river through a pump and it is analyzed in a vessel, which is shielded with Pb. The full calibration of the monitors was performed experimentally, except for the efficiency curve, which was set using validated Monte Carlo simulations with the EGS5 code system. After the calibration, the monitors permitted the identification and quantification of the involved isotopes in a possible radioactive increment and made it possible to discard possible leaks in the nuclear plants. As an example, a radiological increment during rain is used to show the advantages of gamma-ray spectrometry. To study the capabilities of the monitor, the minimum detectable activity concentrations for (131)I, (137)Cs and (40)K are presented for different integration times. PMID:23827508

Casanovas, R; Morant, J J; Salvadó, M

2013-10-01

369

Calibration and Unfolding of the Pulse Height Spectra of Liquid Scintillator-Based Neutron Detectors Using Photon Sources  

NASA Astrophysics Data System (ADS)

An accurate energy calibration of a 5? × 2? BC501A liquid scintillator-based neutron detector by means of photon sources and the unfolding of pulse height spectra are described. The photon responses were measured with 22Na, 137Cs and 54Mn photon sources and simulated using the GRESP code, which was developed at the Physikalisch Technische Bundesanstalt in Germany. Pulse height spectra produced by three different photon sources were employed to investigate the effects of the unfolding techniques. It was found that the four unfolding codes of the HEPRO and UMG3.3 packages, including GRAVEL, UNFANA, MIEKE and MAXED, performed well with the test spectra and produced generally consistent results. They could therefore be used to obtain neutron energy spectra in tokamak experiments.

Xie, Xufei; Yuan, Xi; Zhang, Xing; Fan, Tieshuan; Chen, Jinxiang; Li, Xiangqing

2012-06-01

370

Characterization of a scintillating mini-detector for time-of-flight positron emission tomography with depth-of-interaction  

NASA Astrophysics Data System (ADS)

By exploiting a suitable treatment of the scintillator surfaces, along with silicon photomultiplier photodetectors and specific algorithms for raw data analysis, we achieved a remarkable tradeoff between energy, time, and depth-of-interaction (DOI) resolution, thus supporting the feasibility of a prostate time-of-flight positron emission tomography probe, magnetic resonance imaging compatible, with the required features and performance. In numbers this means a detector element of 1.5 mm × 1.5 mm × 10 mm, promising to achieve at the same time energy resolution around 11.5%, coincidence resolving time around 300 ps corresponding to a space resolution <5 cm along the line of response, and DOI resolution even below 1 mm. We stress that such a time resolution allows to increase significantly the noise equivalent counting rate, and consequently improve the image quality and the lesion detection capability.

Cosentino, Luigi; Finocchiaro, Paolo; Pappalardo, Alfio; Garibaldi, Franco

2012-08-01

371

DETECTORS AND EXPERIMENTAL METHODS: Study of neutron response for two hybrid RPC setups using the GEANT4 MC simulation approach  

NASA Astrophysics Data System (ADS)

The present article describes a detailed neutron simulation study in the energy range 10-10 MeV to 1.0 GeV for two different RPC configurations. The simulation studies were taken by using the GEANT4 MC code. Aluminum was utilized on the GND and readout strips for the (a) Bakelite-based and (b) glass-based RPCs. For the former type of RPC setup the neutron sensitivity for the isotropic source was Sn = 2.702 × 10-2 at En = 1.0 GeV, while for the latter type of RPC, the neutron sensitivity for the same source was evaluated as Sn = 4.049 × 10-2 at En = 1.0 GeV. These results were further compared with the previous RPC configuration in which copper was used for ground and pickup pads. Additionally Al was employed at (GND+strips) of the phosphate glass RPC setup and compared with the copper-based phosphate glass RPC. Good agreement with sensitivity values was obtained with the current and previous simulation results.

M., Jamil; Rhee T., J.; Jeon J., Y.

2009-10-01

372

Neutron\\/Gamma Discrimination Utilizing Fuzzy C-Means Clustering of the Signal from the Liquid Scintillator  

Microsoft Academic Search

The fuzzy c-means (FCM) clustering method was applied to the neutron\\/gamma discrimination of the pulses from the liquid scintillator. An experimental setup termed the portable real-time n\\/? discriminator with a BC-501A liquid scintillator detector was used to collect waveforms with a 500 Ms\\/s, 12 bit sampling ADC. The FCM clustering and PGA were applied to the same pulses dataset respectively

Xiaoliang Luo; Guofu Liu; Jun Yang

2010-01-01

373

Co-doping of CeBr3 scintillator detectors for energy resolution enhancement  

NASA Astrophysics Data System (ADS)

CeBr3 gamma-ray spectrometers are preferable to LaBr3:Ce ones for low-count-rate experiments because of their low intrinsic activity and consequently increased detection sensitivity. A drawback of CeBr3 is a nonoptimum energy resolution, i.e. 4% at 662 keV. Here we demonstrate that aliovalent co-doping techniques are effective to enhance the CeBr3 energy resolution to at least 3%. Such an enhancement is achieved because of a more proportional energy response of the scintillation.

Quarati, F. G. A.; Alekhin, M. S.; Krämer, K. W.; Dorenbos, P.

2014-01-01

374

Spectral Modeling of Scintillator for the NEMO-3 and SuperNEMO Detectors  

SciTech Connect

We have constructed a GEANT4-based detailed softwaremodel 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 wavelength-dependent properties of the calorimeter are taken into account. In this article, we briefly describe our modeling approach and results of our studies.

A. J. Caffrey; J. J. Horkley

2011-01-01

375

6-MVp x-ray imaging with a transparent scintillator x-ray detector  

NASA Astrophysics Data System (ADS)

In a previous paper an x-ray medical imaging system was described that used a liquid nitrogen cooled slow-scan CCD TV camera coupled to a Gd2O3(Eu) transparent ceramic scintillator plate with a high speed macro lens. This imaging system, which has a high spatial resolution and high x-ray quantum efficiency, suffers in the normal diagnostic x-ray energy range from added noise due to the secondary light photon quantum sink. For each x-ray photon absorbed, less than one electron is produced in a CCD pixel. However in the x-ray energy range used in radiation therapy the light output per absorbed x-ray photon is much higher, making the transparent scintillator technique more practical. Also the dose applied in radiation therapy is high anyway, allowing the use of higher dose to give better image quality. The 16-bit resolution of the cooled CCD allows very accurate x-ray absorption data to be acquired compared to the 8-bit CCDs used in commercially available portal imagers. Images have been acquired of human bones using the Gd2O3(Eu) screen and a 3 mm thick CsI(Tl) crystal.

Zeman, Herbert D.; Samant, Sanjiv S.; Rasmussen, Jacob

1997-05-01

376

A thermal neutron mini-detector with SiPM and scintillating fibers  

NASA Astrophysics Data System (ADS)

We developed and tested a simple prototype of thermal neutron detector suitable for inexpensive deployment in the decommissioning and storage of radioactive waste, as well as for mapping the flux in the out-of-core regions of fission reactors. Though the prototype version we tested provides the neutron rate by subtracting the gamma background measured with a twin detector insensitive to neutrons, a simple geometrical improvement can strongly reduce the gamma contribution.

Barbagallo, M.; Cosentino, L.; Greco, G.; Guardo, G.; Montereali, R. M.; Pappalardo, A.; Scirè, C.; Scirè, S.; Vincenti, M. A.; Finocchiaro, P.

2011-10-01

377

Performance measurements of a new large-area neutron scintillation detector system  

Microsoft Academic Search

During the upgrade of the small-angle neutron scattering instrument KWS-1 at the research reactor FRJ-2, the 15-yr-old detector system has been replaced. While the Anger camera-based concept of the detector remained unchanged, the signal and data processing branch has been completely revised. Because of higher count rate requirements, a highly configurable parallel readout electronics has been developed aiming at counting

G. Kemmerling; U. Bunten; U. Clemens; R. Engels; M. Heiderich; W. Pykhout-Hintzen; H. Rongen; J. Schelten; D. Schwahn; K. Zwoll

2004-01-01

378

Development of a novel multi-point plastic scintillation detector with a single optical transmission line for radiation dose measurement*  

PubMed Central

Purpose The goal of this study was to develop a novel multi-point plastic scintillation detector (mPSD) capable of measuring the dose accurately at multiple positions simultaneously using a single optical transmission line. Methods A 2-point mPSD used a band-pass approach that included splitters, color filters, and an EMCCD camera. The 3-point mPSD was based on a new full-spectrum approach, in which a spectrograph was coupled to a CCD camera. Irradiations of the mPSDs and of an ion chamber were performed with a 6-MV photon beam at various depths and lateral positions in a water tank. Results For the 2-point mPSD, the average relative differences between mPSD and ion chamber measurements for the depth-dose were 2.4±1.6% and 1.3±0.8% for BCF-60 and BCF-12, respectively. For the 3-point mPSD, the average relative differences over all conditions were 2.3±1.1%, 1.6±0.4%, and 0.32±0.19% for BCF-60, BCF-12, and BCF-10, respectively. Conclusions This study demonstrates the practical feasibility of mPSDs. This type of detector could be very useful for pre-treatment quality assurance applications as well as an accurate tool for real-time in vivo dosimetry.

Therriault-Proulx, Francois; Archambault, Louis; Beaulieu, Luc; Beddar, Sam

2013-01-01

379

Study of linearity and internal background for LaBr3(Ce) ?-ray scintillation detector  

NASA Astrophysics Data System (ADS)

Cerium-doped lanthanum bromide, LaBr3(Ce), crystal is the latest among the scintillation counters and shows same attracting properties for ? spectroscopy that makes it a suitable solution for security, medical, geophysics and high energy physics applications. LaBr3(Ce) exhibits a proportional light yield response to ?-ray energy. Very good linearity was seen up to 2 MeV. LaBr3(Ce) has also relatively high intrinsic radiation background due to naturally occurring 138La and 227Ac radioisotopes. A good use of LaBr3(Ce) needs an accurate determination of the self-activity, particularly when low background is required or when events are collected at very low trigger rates. The impact of internal background on energy resolution and linearity is discussed.

Lavagno, A.; Gervino, G.; Scarfone, A.

2013-08-01

380

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

381

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

PubMed Central

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

2011-01-01

382

ScintSim1: A new Monte Carlo simulation code for transport of optical photons in 2D arrays of scintillation detectors.  

PubMed

Two-dimensional (2D) arrays of thick segmented scintillators are of interest as X-ray detectors for both 2D and 3D image-guided radiotherapy (IGRT). Their detection process involves ionizing radiation energy deposition followed by production and transport of optical photons. Only a very limited number of optical Monte Carlo simulation models exist, which has limited the number of modeling studies that have considered both stages of the detection process. We present ScintSim1, an in-house optical Monte Carlo simulation code for 2D arrays of scintillation crystals, developed in the MATLAB programming environment. The code was rewritten and revised based on an existing program for single-element detectors, with the additional capability to model 2D arrays of elements with configurable dimensions, material, etc., The code generates and follows each optical photon history through the detector element (and, in case of cross-talk, the surrounding ones) until it reaches a configurable receptor, or is attenuated. The new model was verified by testing against relevant theoretically known behaviors or quantities and the results of a validated single-element model. For both sets of comparisons, the discrepancies in the calculated quantities were all <1%. The results validate the accuracy of the new code, which is a useful tool in scintillation detector optimization. PMID:24600168

Mosleh-Shirazi, Mohammad Amin; Zarrini-Monfared, Zinat; Karbasi, Sareh; Zamani, Ali

2014-01-01

383

ScintSim1: A new Monte Carlo simulation code for transport of optical photons in 2D arrays of scintillation detectors  

PubMed Central

Two-dimensional (2D) arrays of thick segmented scintillators are of interest as X-ray detectors for both 2D and 3D image-guided radiotherapy (IGRT). Their detection process involves ionizing radiation energy deposition followed by production and transport of optical photons. Only a very limited number of optical Monte Carlo simulation models exist, which has limited the number of modeling studies that have considered both stages of the detection process. We present ScintSim1, an in-house optical Monte Carlo simulation code for 2D arrays of scintillation crystals, developed in the MATLAB programming environment. The code was rewritten and revised based on an existing program for single-element detectors, with the additional capability to model 2D arrays of elements with configurable dimensions, material, etc., The code generates and follows each optical photon history through the detector element (and, in case of cross-talk, the surrounding ones) until it reaches a configurable receptor, or is attenuated. The new model was verified by testing against relevant theoretically known behaviors or quantities and the results of a validated single-element model. For both sets of comparisons, the discrepancies in the calculated quantities were all <1%. The results validate the accuracy of the new code, which is a useful tool in scintillation detector optimization.

Mosleh-Shirazi, Mohammad Amin; Zarrini-Monfared, Zinat; Karbasi, Sareh; Zamani, Ali

2014-01-01

384

Determination of the quenching correction factors for plastic scintillation detectors in therapeutic high-energy proton beams  

PubMed Central

The plastic scintillation detectors (PSD) have many advantages over other detectors in small field dosimetry due to its high spatial resolution, excellent water equivalence and instantaneous readout. However, in proton beams, the PSDs will undergo a quenching effect which makes the signal level reduced significantly when the detector is close to Bragg peak where the linear energy transfer (LET) for protons is very high. This study measures the quenching correction factor (QCF) for a PSD in clinical passive-scattering proton beams and investigates the feasibility of using PSDs in depth-dose measurements in proton beams. A polystyrene based PSD (BCF-12, ?0.5mm×4mm) was used to measure the depth-dose curves in a water phantom for monoenergetic unmodulated proton beams of nominal energies 100, 180 and 250 MeV. A Markus plane-parallel ion chamber was also used to get the dose distributions for the same proton beams. From these results, the QCF as a function of depth was derived for these proton beams. Next, the LET depth distributions for these proton beams were calculated by using the MCNPX Monte Carlo code, based on the experimentally validated nozzle models for these passive-scattering proton beams. Then the relationship between the QCF and the proton LET could be derived as an empirical formula. Finally, the obtained empirical formula was applied to the PSD measurements to get the corrected depth-dose curves and they were compared to the ion chamber measurements. A linear relationship between QCF and LET, i.e. Birks' formula, was obtained for the proton beams studied. The result is in agreement with the literature. The PSD measurements after the quenching corrections agree with ion chamber measurements within 5%. PSDs are good dosimeters for proton beam measurement if the quenching effect is corrected appropriately.

Wang, L L W; Perles, L A; Archambault, L; Sahoo, N; Mirkovic, D; Beddar, S

2013-01-01

385

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

2012-04-21

386

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

387

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

388

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

PubMed Central

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

Wang, Lilie L. W.; Beddar, Sam

2011-01-01

389

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

Microsoft Academic Search

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)

Fábio E da Costa; Margarida M. Hamada

2002-01-01

390

Programmable integrated front-end for SiPM/PMT PET detectors with continuous scintillating crystal  

NASA Astrophysics Data System (ADS)

AMIC architecture has been introduced in previous works in order to provide a generic and expandable solution for implementing large number of outputs SiPM array/PMT detectors. The underlying idea in AMIC architecture is to calculate the moments of the detected light distribution in an analog fashion. These moments provide information about energy, x/y position, etc. of the light distribution of the detected event. Moreover this means that a small set of signals contains most of the information of the event, thus reducing the number of channels to be acquired. This paper introduces a new front-end device AMIC2GR which implements the AMIC architecture improving the features of the former integrated devices. Higher bandwidth and filtering coefficient precision along with a lower noise allow to apply some detector enhancements. Inhomogeneity among detector elements throughout the array can be reduced. Depth of interaction measurements can be obtained from the light distribution analysis. Also a common trigger signal can be obtained for the whole detector array. Finally AMIC2GR preamplifier stage close to SiPM output signals optimizes signal to noise ratio, which allows to reduce SiPM gain by using lower operating voltages thus reducing dark noise.

Herrero-Bosch, V.; Monzó, J. M.; Ros, A.; Aliaga, R. J.; González, A.; Montoliu, C.; Colom-Palero, R. J.; Benlloch, J. M.

2012-12-01

391

Performance of Neutron Detector and Bottom Trigger Scintillator of the Space Instrument Pamela  

Microsoft Academic Search

PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) is a satellite-borne experiment designed to study charged particles in the cosmic radiation over the largest energy range ever achieved. The apparatus is composed by a magnetic spectrometer, to determine the charge of the particles, an electromagnetic calorimeter and a neutron detector (ND), which perform the particle identification; in addition, an

V. Malvezzi

2006-01-01

392

Alignment of the Near Detector Scintillator Modules Using Cosmic Ray Muons.  

National Technical Information Service (NTIS)

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 cal...

K. Lang R. Ospanov

2005-01-01

393

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

394

Theorie und Messung der Energie- und Risetimeaufloesung an Szintillations-Detektoren im Harten Roentgenbereich (Theory and Measurement of the Energy and Risetime Resolution of Scintillation Detectors in Hard X ray Area).  

National Technical Information Service (NTIS)

Several scintillation detectors are examined, and the measurement results are compared in order to increase the energy resolution. The uniformity of each detector was estimated by scanning of the detector surface with a monochromatic x-ray source and by m...

J. Schneider

1990-01-01

395

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

396

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

397

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

PubMed Central

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?×?20?×?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?×?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.

2012-01-01

398

Scintillator counters with WLS fiber/MPPC readout for the side muon range detector (SMRD) of the T2K experiment  

NASA Astrophysics Data System (ADS)

The T2K neutrino experiment at J-PARC uses a set of near detectors to measure the properties of an unoscillated neutrino beam and neutrino interaction cross-sections. One of the sub-detectors of the near-detector complex, the side muon range detector (SMRD), is described in the paper. The detector is designed to help measure the neutrino energy spectrum, to identify background and to calibrate the other detectors. The active elements of the SMRD consist of 0.7 cm thick extruded scintillator slabs inserted into air gaps of the UA1 magnet yokes. The readout of each scintillator slab is provided through a single WLS fiber embedded into a serpentine-shaped groove. Two Hamamatsu multi-pixel avalanche photodiodes (MPPC's) are coupled to both ends of the WLS fiber. This design allows us to achieve a high MIP detection efficiency of greater than 99%. A light yield of 25-50 p.e./MIP, a time resolution of about 1 ns and a spatial resolution along the slab better than 10 cm were obtained for the SMRD counters.

Izmaylov, A.; Aoki, S.; Blocki, J.; Brinson, J.; Dabrowska, A.; Danko, I.; Dziewiecki, M.; Ellison, B.; Golyshkin, L.; Gould, R.; Hara, T.; Hartfiel, B.; Holeczek, J.; Khabibullin, M.; Khotjantsev, A.; Kielczewska, D.; Kisiel, J.; Kozlowski, T.; Kudenko, Yu.; Kurjata, R.; Kutter, T.; Lagoda, J.; Liu, J.; Marzec, J.; Metcalf, W.; Mijakowski, P.; Mineev, O.; Musienko, Yu.; Naples, D.; Nauman, M.; Northacker, D.; Nowak, J.; Paolone, V.; Posiadala, M.; Przewlocki, P.; Reid, J.; Rondio, E.; Shaykhiev, A.; Sienkiewicz, M.; Smith, D.; Sobczyk, J.; Stodulski, M.; Straczek, A.; Sulej, R.; Suzuki, A.; Swierblewski, J.; Szeglowski, T.; Szeptycka, M.; Wachala, T.; Warner, D.; Yershov, N.; Yano, T.; Zalewska, A.; Zaremba, K.; Ziembicki, M.

2010-11-01

399

Measurements of the atmospheric muon flux using a mobile detector based on plastic scintillators read-out by optical fibers and PMTs  

NASA Astrophysics Data System (ADS)

Precise measurements of the muon flux are important for different practical applications, in environmental studies and for the estimation of the water equivalent depths of underground sites. A first configuration of the mobile detector was composed of two 1 m2 scintillator plates, each viewed by wave length shifters and read out by two PMTs (Photomultiplier Tubes). A more recent configuration of the mobile muon detectors, set up in IFIN-HH, Romania, consists of two 1 m2 detection layers, each one including four 1×0.25 m2 large scintillator plates. The light output in each plate is collected by twelve optical fibers and then read out by one PMT. The calibration has been made by comparing the energy deposit spectrum of minimum ionizing particles with the spectra simulated with the GEANT4 code. The device is used to measure the muon flux on different locations at the surface and underground.

Stanca, D. I.; Mitrica, B.; Petcu, M.; Brancus, I. M.; Jipa, A.; Haungs, A.; Rebel, H.; Saftoiu, A.; Toma, G.

2013-02-01

400

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

401

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

402

Evaluation of LiYF4 as a neutron scintillation detector  

Microsoft Academic Search

LiYF4 doped with 1% Ce, and manufactured using fully enriched 99.6% 36Li, has been evaluated as a neutron detector in a comparison with an optimum form of Ce-doped lithium aluminosilicate glass. Room temperature absorption and excitation spectra are presented and discussed. The pulse height of the 36Li (n, alpha ) reaction using moderated Am\\/Be neutrons is shown to be a

A. R. Spowart

1983-01-01

403

A Measurement of the Response of an SCG1-C Scintillation Glass Shower Detector to 2-17.5 GeV Positrons  

Microsoft Academic Search

The response of an electromagnetic shower counter constructed from the new scintillation glass (SCG1-C, Ohara Optical Glass, Inc.) to positrons in the energy range 2 to 17.5 GeV was measured. The energy resolution of this 18.4 radiation length detector plus its attendant SF5 lead glass shower counter array was measured to be sigma\\/E = (1.64 plus or minus 0.14)% +

B. Cox; G. Hale; P. O. Mazur; R. L. Wagner; D. E. Wagoner; H. Areti; S. Conetti; P. Lebrun; T. Ryan; J. E. Brau; R. A. Gearhart

1983-01-01

404

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

405

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

406

Experimental Setup  

NASA Astrophysics Data System (ADS)

To run a successful electrochemical experiment it is essential that the experimental setup is electrically correct and appropriate for the experiment planned. There are several points that should be carefully considered before the experiments are started. They include proper choice of the working, reference and auxiliary electrodes, proper selection of the solvent and supporting electrolyte, proper selection of the electroanalytical technique and its parameters, proper wiring of the electrochemical circuit and, finally, proper setting of the parameters of the potentiostat/voltammograph used.

Stojek, Zbigniew

407

LaCl 3(Ce) scintillation detector applications for environmental gamma-ray measurements of low to high dose rates  

Microsoft Academic Search

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 25.4mm×25.4mm LaCl3(Ce) crystal are studied and compared to those

Masahiro Tsutsumi; Yoshihiko Tanimura

2006-01-01

408

A method to achieve spatial linearity and uniform resolution at the edges of monolithic scintillation crystal detectors.  

PubMed

We have performed Monte Carlo simulations of the scintillation light transport between adjacent monolithic LYSO crystals that are optically coupled together using coupling media of varying refractive index. The scintillation light from the crystals was read out by SiPM arrays from the large crystal face. Scintillation event positioning results show that this optical coupling technique preserves the shape of the light spread function near and across the interface between the two crystals in order to substantially reduce the edge-artifacts observed in monolithic scintillation crystals, while not degrading the timing performance. PMID:24841984

Vinke, Ruud; Levin, Craig S

2014-06-21

409

Set-up, testing, and first results from the application of a laser for research and development for the Solenoidal Detector Collaboration of the SSC. Foreign trip report, July 15--26, 1991.  

National Technical Information Service (NTIS)

The purpose of this trip was the set-up, testing, and first results from the application of a laser to be used at the University of Maryland for research and development on chamber types for the Solenoidal Detector Collaboration of the Superconducting Sup...

A. H. Ball

1991-01-01

410

Thin-film scintillators for extended ultraviolet /UV/ response silicon detectors  

NASA Technical Reports Server (NTRS)

The preparation and radiometric properties of silicon detectors coated with fluorescent thin films are described. The films are deposited from solutions of clear plastics, such as acrylic resins, polyvinyl toluene or polystyrene, and of organic laser dyes in a common solvent. They are optically clear, mechanically and chemically stable, yet easily applied and removed. Multiple doped films of a few microns thickness exhibit broad-band absorption from less than 250 nm to about 450 nm and narrow band emissions with peaks ranging from 380 nm to 600 nm. Internal quantum efficiencies are close to 100 percent and fluorescence decay times are in the nanosecond range. When deposited on optically denser media, a large fraction of the fluorescent emission is trapped in the substrate. Silicon photodiodes coated with multiple doped films exhibit high external quantum efficiencies and virtually flat photon response in the near UV.

Viehmann, W.

1979-01-01

411

Extruding plastic scintillator at Fermilab  

Microsoft Academic Search

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

Anna Pla-Dalmau; Alan D. Bross; Victor V. Rykalin

2003-01-01

412

BC404 scintillators as gamma locators studied via Geant4 simulations  

NASA Astrophysics Data System (ADS)

In many applications in industry and academia, an accurate determination of the direction from where gamma rays are emitted is either needed or desirable. Ion-beam therapy treatments, the search for orphan sources, and homeland security applicatio