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1

WILLI – a scintillator detector setup for studies of the zenith and azimuth variation of charge ratio and flux of atmospheric muons  

Microsoft Academic Search

The primary and secondary components of the cosmic radiation are influenced by the geomagnetic field. This leads - in addition to the variation with the zenith angle - to an azimuth dependence, in particular of the ratio of positive and negative muons, pronounced as East-West effect of muon charge ratio for low energy muons. The compact scintillator detector arrangement, WILLI,

I. M. Brancus; H. Rebel; A. Haungs; B. Mitrica; A. Bercuci; A. Saftoiu; M. Petcu; J. Wentz; O. Sima; G. Toma; M. Duma; C. Aiftimiei

2008-01-01

2

a Subminiature Scintillation Detector for Catheter Operation  

NASA Astrophysics Data System (ADS)

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

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

2006-04-01

3

Encapsulated scintillation detector  

SciTech Connect

An encapsulated scintillation detector is disclosed in which a detector crystal or the like is encapsulated in a hermetically sealed housing having a light-transmitting window at one end. In some instances, the window is mounted in a window assembly by a compression seal established by the differential coefficient of expansion and contraction during the cooling of the assembly. In other instances, the window is chemically bonded to the ring with or without a compression seal. The window is mounted within a ring, which is in turn welded to the end of a tubular body portion of the housing along thin weld flanges to reduce the amount of weld heat which must be applied. A thermal barrier is provided to resist the flow of welding heat from the weld to the seal between the ring and the window. Such thermal barrier includes a zone of relatively thin section located between the weld zone and the seal through which weld heat must flow. The zone of relatively thin cross section is, in some embodiments, provided by a groove cut partially through the wall of the ring. A layer of low friction material such as teflon is positioned between the tubular body and the crystal to minimize friction resisting relative axial movement created by differential coefficients of thermal expansion.

Toepke, I.L.

1983-05-10

4

Characterization of liquid scintillation detectors  

NASA Astrophysics Data System (ADS)

Five scintillation detectors of different scintillator size and type were characterized. The pulse height scale was calibrated in terms of electron light output units using photon sources. The response functions for time-of-flight (TOF)-selected monoenergetic neutrons were experimentally determined and also simulated with the NRESP code over a wide energy range. A comparison of the measured and calculated response functions allows individual characteristics of the detectors to be determined and the response matrix to be reliably derived. Various applications are discussed.

Schmidt, D.; Asselineau, B.; Böttger, R.; Klein, H.; Lebreton, L.; Neumann, S.; Nolte, R.; Pichenot, G.

2002-01-01

5

The most powerful scintillator supernovae detector: LVD  

Microsoft Academic Search

Summary The Large Volume Detector (LVD) in the Gran Sasso underground Laboratory is a multipurpose detector consisting of a large volume of liquid scintillator interleaved with limited streamer tubes. In this paper we discuss its power to study low-energy cosmic neutrinos. The results show that the first LVD tower (368 tons of liquid scintillator) is well suited to detect neutrinos

M. Aglietta; B. Alpat; E. D. Alyea; P. Antonioli; G. Anzivino; G. Badino; Y. Ban; G. Bari; M. Basile; A. Benelli; V. S. Berezinsky; L. Bergamasco; S. Bianco; A. Bizzetti; G. Bruni; Y. Cao; G. Cara Romeo; R. Casaccia; C. Castagnoli; A. Castellina; K. Chen; R. Chen; J. A. Chinellato; L. Cifarelli; G. Cini; S. Cong; A. Contin; V. L. Dadikin; M. Dardo; A. De Silva; M. Deutsch; L. G. Dos Santos; R. I. Enikeev; F. L. Fabbri; W. Fulgione; P. Galeotti; P. L. Ghia; P. Giusti; F. Grianti; S. Gu; E. S. Hafen; P. Haridas; G. Iacobucci; N. Inoue; F. F. Khalchukov; E. V. Korolkova; P. V. Kortchaguin; V. B. Kortchaguin; V. A. Kudryavtsev; G. Landi; K. Lau; X. Lin; L. Lu; J. Ma; Z. Ma; G. Maccarrone; A. S. Malguin; Z. Mao; M. A. Markov; T. Massam; B. Mayes; N. Mengotti Silva; A. Misaki; G. H. Mo; B. Monteleoni; C. Morello; J. Moromisato; R. Nania; G. Navarra; L. Panaro; D. Parks; P. G. Pelfer; L. Periale; P. Picchi; P. Pinna; L. Pinsky; I. A. Pless; M. Pu; J. Pyrlyk; J. Qiu; V. G. Ryasny; O. G. Ryazhskaya; O. Saavedra; K. Saitoh; D. Sanders; G. Sartorelli; S. Sarwar; D. Shen; V. P. Talochkin; H. Tang; J. Tang; W. Tian; G. C. Trinchero; A. Turtelli; I. Uman; P. Vallania; S. Vernetto; E. von Goeler; L. Votano; T. Wada; F. Wang; H. Wang; S. Wang; R. Weathers; R. Weinstein; M. Widgoff; L. Xu; Z. Xu; V. F. Yakushev; I. Yamamoto; G. Yi; A. Zallo; G. T. Zatsepin; X. Zhou; Q. Zhu; X. Zhu; B. Zhuan; A. Zichichi

1992-01-01

6

Position reconstruction in large-area scintillating fibre detectors  

NASA Astrophysics Data System (ADS)

A new analysis procedure has been developed for the large-area scintillating fibre detectors with position-sensitive photomultiplier (PSPM) readout used for heavy ions in the LAND set-up at GSI. It includes gain matching of the PSPM, calibration of the PSPM fibre mask and hit reconstruction. This procedure allows for a quasi-online calibration of this tracking device. It also allows for a precise determination of the position close to the intrinsic detector resolution of 1 mm pitch together with careful treatment of individual event accuracies.

Mahata, K.; Johansson, H. T.; Paschalis, S.; Simon, H.; Aumann, T.

2009-09-01

7

Large volume flow-through scintillating detector  

DOEpatents

A large volume flow through radiation detector for use in large air flow situations such as incinerator stacks or building air systems comprises a plurality of flat plates made of a scintillating material arranged parallel to the air flow. Each scintillating plate has a light guide attached which transfers light generated inside the scintillating plate to an associated photomultiplier tube. The output of the photomultiplier tubes are connected to electronics which can record any radiation and provide an alarm if appropriate for the application.

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

1995-01-01

8

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

9

Current trends in scintillator detectors and materials  

SciTech Connect

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 now incorporated in commercial positron emission tomography (PET) cameras. There have been advances in understanding the fundamental mechanisms that limit energy resolution, and several recently discovered materials (such as LaBr3:Ce) possess energy resolution that approaches that of direct solid state detectors. Finally, there are indications that a neglected class of scintillator materials that exhibit near band-edge fluorescence could provide scintillators with sub-nanosecond decay times and high luminescent efficiency.

Moses, William W.

2001-10-23

10

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

11

Temperature dependence of BCF plastic scintillation detectors.  

PubMed

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. PMID:23574889

Wootton, Landon; Beddar, Sam

2013-05-01

12

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

13

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. PMID:23574889

Wootton, Landon; Beddar, Sam

2013-01-01

14

Scintillation detectors based on silicon microfluidic channels  

NASA Astrophysics Data System (ADS)

Microfluidic channels obtained by SU-8 photolithography and filled with liquid scintillators were recently demonstrated to be an interesting technology for the implementation of novel particle detectors. The main advantages of this approach are the intrinsic radiation resistance resulting from the simple microfluidic circulation of the active medium and the possibility to manufacture devices with high spatial resolution and low material budget using microfabrication techniques. Here we explore a different technological implementation of this concept, reporting on scintillating detectors based on silicon microfluidic channels. A process for manufacturing microfluidic devices on silicon substrates, featuring microchannel arrays suitable for light guiding, was developed. Such process can be in principle combined with standard CMOS processing and lead to a tight integration with the readout photodetectors and electronics in the future. Several devices were manufactured, featuring microchannel geometries differing in depth, width and pitch. A preliminary characterization of the prototypes was performed by means of a photomultiplier tube coupled to the microchannel ends, in order to detect the scintillation light produced upon irradiation with beta particles from a 90Sr source. The photoelectron spectra thus obtained were fitted with the expected output function in order to extract the light yield.

Maoddi, P.; Mapelli, A.; Bagiacchi, P.; Gorini, B.; Haguenauer, M.; Lehmann Miotto, G.; Murillo Garcia, R.; Safai Tehrani, F.; Veneziano, S.; Renaud, P.

2014-01-01

15

Induced activity in scintillation detectors in space  

NASA Astrophysics Data System (ADS)

An experimental system was flown on the Space Shuttle Columbia from August 8 to 13, 1989 as part of the Shuttle Activation Monitor (SAM) program [P.S. Haskins et al., IEEE Trans. Nucl. Sci. NS-37 (6) (1990) 1256]. Gamma-ray spectra were collected both during flight and after landing from two 3 in. × 3 in. scintillation detectors, Nal and BGO. The shuttle was in a high inclination (57 °) orbit, at an altitude of 300 km which provided exposure to the trapped charged particles in the South Atlantic Anomaly (SAA) as well as the electrons in the Polar regions. The induced radiation observed by the detectors resulted from both external and internal sources activated by the interaction with the energetic charged particles. The flight data analysis indicates variation of the induced external radiation as a function of geomagnetic coordinates and amount of shielding, whereas the post-landing data exhibits induced internal radiation from the two different types of detector materials.

Zhao, X.; Ramayya, A. V.; Haskins, P. S.; McKisson, J. E.; Ely, D. W.; Weisenberger, A. G.; Piercey, R. B.

1991-05-01

16

Nonproportionality of Scintillator Detectors: Theory and Experiment  

SciTech Connect

On the basis of nonproportionality data obtained for several scintillators, we have developed a theory 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 was employed to allow for exciton-exciton annihilation. We then developed a second theory to deduce the degradation in resolution that results from nonproportionality by evoking Landau fluctuations, which are essentially variations in the deposited energy density that occur as the high energy electron travels along its trajectory. In general there is good agreement with the data, in terms of fitting the nonproportionality curves and reproducing the literature values of nonproportionality's contribution to the scintillator resolution. With the resurgence of interest in developing scintillator detectors that have good energy resolution, an improved understanding of nonproportionality has become a crucial matter since it presents the fundamental limit to the achievable resolution. In order to hasten an improved understanding of scintillator nonproportionality, we have constructed an instrument referred to as SLYNCI (Scintillator Light Yield Nonproportionality Compton Instrument). This is a second-generation instrument to the original device developed by Valentine and coworkers, wherein several new principles of operation have served to increase the data rate by an order of magnitude as discussed in detail in References. In the present article, the focus is on a theory to describe the measured electron response, which is the light yield as a function of the electron energy. To do this, we account for transport of carriers and excitons, in terms of how they transfer their energy to the activators with competition from nonradiative decay pathways. This work builds on the original work of Murray and coworkers, and on the understanding of excitons. We then provide a new theoretical framework from which the nonproportionality data is reduced to a measure of the degradation in resolution. We have utilized data obtained from SLYNCI to obtain accurate nonproportionality data on several scintillators, and have developed a theory to describe the carrier dynamics to fit the data for the light yield versus electron energy.

Payne, Stephen; Cherepy, Nerine; Hull, Giulia; Valentine, John; Moses, William; Choong, Woon-Seng

2009-08-17

17

TOF-PET detector concept based on organic scintillators  

E-print Network

In this contribution we present a new concept of the large acceptance detector systems based on organic scintillators which may allow for simultaneous diagnostic of large fraction of the human body. Novelty of the concept lies in employing large blocks of polymer scintillators instead of crystals as detectors of annihilation quanta, and in using predominantly the timing of signals instead of their amplitudes.

P. Moskal; T. Bednarski; P. Bia?as; M. Ciszewska; E. Czerwi?ski; A. Heczko; M. Kajetanowicz; ?. Kap?on; A. Kochanowski; G. Konopka-Cupia?; G. Korcyl; W. Krzemie?; K. ?ojek; J. Majewski; W. Migda?; M. Molenda; Sz. Nied?wiecki; M. Pa?ka; Z. Rudy; P. Salabura; M. Silarski; A. S?omski; J. Smyrski; J. Zdebik; M. Zieli?ski

2013-05-23

18

TOF-PET detector concept based on organic scintillators  

E-print Network

In this contribution we present a new concept of the large acceptance detector systems based on organic scintillators which may allow for simultaneous diagnostic of large fraction of the human body. Novelty of the concept lies in employing large blocks of polymer scintillators instead of crystals as detectors of annihilation quanta, and in using predominantly the timing of signals instead of their amplitudes.

Moskal, P; Bia?as, P; Ciszewska, M; Czerwi?ski, E; Heczko, A; Kajetanowicz, M; Kap?on, ?; Kochanowski, A; Konopka-Cupia?, G; Korcyl, G; Krzemie?, W; ?ojek, K; Majewski, J; Migda?, W; Molenda, M; Nied?wiecki, Sz; Pa?ka, M; Rudy, Z; Salabura, P; Silarski, M; S?omski, A; Smyrski, J; Zdebik, J; Zieli?ski, M

2013-01-01

19

New setup for the characterisation of the AGATA detectors  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

20

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

21

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

22

Setup optimization toward accurate ageing studies of gas filled detectors  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

23

Performance comparison of scintillators for alpha particle detectors  

NASA Astrophysics Data System (ADS)

Scintillation detectors for alpha particles are often used in nuclear fuel facilities. Alpha particle detectors have also become important in the research field of radionuclide therapy using alpha emitters. ZnS(Ag) is the most often used scintillator for alpha particle detectors because its light output is high. However, the energy resolution of ZnS(Ag)-based scintillation detectors is poor because they are not transparent. A new ceramic sample, namely the cerium doped Gd2Si2O7 (GPS) scintillator, has been tested as alpha particle detector and its performances have been compared to that one of three different scintillating materials: ZnS(Ag), GAGG and a standard plastic scintillator. The different scintillating materials have been coupled to two different photodetectors, namely a photomultiplier tube (PMT) and a Silicon Photo-multiplier (Si-PM): the performances of each detection system have been compared. Promising results as far as the energy resolution performances (10% with PMT and 14% with Si-PM) have been obtained in the case of GPS and GAGG samples. Considering the quantum efficiencies of the photodetectors under test and their relation to the emission wavelength of the different scintillators, the best results were achieved coupling the GPS with the PMT and the GAGG with the Si-PM

Morishita, Yuki; Yamamoto, Seiichi; Izaki, Kenji; Kaneko, Junichi H.; Toui, Kohei; Tsubota, Youichi; Higuchi, Mikio

2014-11-01

24

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

25

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

26

Optimizing timing performance of silicon photomultiplier-based scintillation detectors  

PubMed Central

Precise timing resolution is crucial for applications requiring photon time-of-flight (ToF) information such as ToF positron emission tomography (PET). Silicon photomultipliers (SiPM) for PET, with their high output capacitance, are known to require custom preamplifiers to optimize timing performance. In this paper, we describe simple alternative front-end electronics based on a commercial low-noise RF preamplifier and methods that have been implemented to achieve excellent timing resolution. Two radiation detectors with L(Y)SO scintillators coupled to Hamamatsu SiPMs (MPPC S10362–33-050C) and front-end electronics based on an RF amplifier (MAR-3SM+), typically used for wireless applications that require minimal additional circuitry, have been fabricated. These detectors were used to detect annihilation photons from a Ge-68 source and the output signals were subsequently digitized by a high speed oscilloscope for offline processing. A coincident resolving time (CRT) of 147 ± 3 ps FWHM and 186 ± 3 ps FWHM with 3 × 3 × 5 mm3 and with 3 × 3 × 20 mm3 LYSO crystal elements were measured, respectively. With smaller 2 × 2 × 3 mm3 LSO crystals, a CRT of 125 ± 2 ps FWHM was achieved with slight improvement to 121 ± 3 ps at a lower temperature (15°C). Finally, with the 20 mm length crystals, a degradation of timing resolution was observed for annihilation photon interactions that occur close to the photosensor compared to shallow depth-of-interaction (DOI). We conclude that commercial RF amplifiers optimized for noise, besides their ease of use, can produce excellent timing resolution comparable to best reported values acquired with custom readout electronics. On the other hand, as timing performance degrades with increasing photon DOI, a head-on detector configuration will produce better CRT than a side-irradiated setup for longer crystals. PMID:23369872

Yeom, Jung Yeol; Vinke, Ruud

2013-01-01

27

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

28

Improved Scintillator Materials for Compact Electron Antineutrino Detectors  

SciTech Connect

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

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

2011-04-27

29

Reactor neutrino experiments with a large liquid scintillator detector  

NASA Astrophysics Data System (ADS)

We discuss several new ideas for reactor neutrino oscillation experiments with a Large Liquid Scintillator Detector. We consider two different scenarios for a measurement of the small mixing angle ?13 with a mobile bar nue source: a nuclear-powered ship, such as a submarine or an icebreaker, and a land-based scenario with a mobile reactor. The former setup can achieve a sensitivity to sin 22?13lesssim0.004 at the 90% confidence level, while the latter performs only slightly better than Double Chooz. Furthermore, we study the precision that can be achieved for the solar parameters, sin 22?12 and ?m212, with a mobile reactor and with a conventional power station. With the mobile reactor, a precision slightly better than from current global fit data is possible, while with a power reactor, the accuracy can be reduced to less than 1%. Such a precision is crucial for testing theoretical models, e.g. quark-lepton complementarity.

Kopp, Joachim; Lindner, Manfred; Merle, Alexander; Rolinec, Mark

2007-01-01

30

Investigation of Plastic Scintillator Detector Configurations for Neutron Studies  

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

31

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

32

Large area silicon avalanche photodiodes for scintillation detectors  

NASA Astrophysics Data System (ADS)

Large area (?1 cm 2) silicon avalanche photodiodes (SiAPDs) have been fabricated and their performance as optical detectors for use with scintillating crystals has been measured. Light sensitivity is measured for hexagonal SiAPDs of 1.57 cm 2 total package area, and the energy and timing resolution is measured for these devices coupled to CsI(Tl) scintillators operating as gamma spectrometers.

Farrell, R.; Olschner, F.; Frederick, E.; McConchie, L.; Vanderpuye, K.; Squillante, M. R.; Entine, G.

1990-03-01

33

Large area silicon avalanche photodiodes for scintillation detectors  

Microsoft Academic Search

Large area (~1 cm2) silicon avalanche photodiodes (SiAPDs) have been fabricated and their performance as optical detectors for use with scintillating crystals has been measured. Light sensitivity is measured for hexagonal SiAPDs of 1.57 cm2 total package area, and the energy and timing resolution is measured for these devices coupled to CsI(Tl) scintillators operating as gamma spectrometers.

R. Farrell; F. Olschner; E. Frederick; L. McConchie; K. Vanderpuye; M. R. Squillante; G. Entine

1990-01-01

34

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

35

Performance of photomultiplier tubes and sodium iodide scintillation detector systems  

NASA Technical Reports Server (NTRS)

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, procedures for measurement of relevant parameters are specified, and results of these measurements are presented.

Meegan, C. A.

1981-01-01

36

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

37

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

38

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

39

Scintillation detectors in gamma spectral logging; geometry, absorption and calibration  

USGS Publications Warehouse

The theory for the evaluation of the effects of geometry in gamma ray absorption is developed for cylindrical scintillation detectors as applicable to borehole gamma spectrometry. The results of a laboratory experiment are shown for comparison. A calibration procedure to determine detector efficiency is given for application to borehole probes. It is shown that the response of a crystal can be separated in terms of geometric effects and instrumentation effects. It is also shown that approximating crystal detectors with point detectors in mathematical theory is grossly oversimplified. (USGS)

Schimschal, Ulrich

1980-01-01

40

Simulation Of Scintillating Fiber Gamma Ray Detectors For Medical Imaging  

Microsoft Academic Search

Plastic scintillating fibers have been shown to be very effective for high spatial and time resolution of gamma rays. They may be expected to significantly improve the resolution of current medical imaging systems such as PET and SPECT. Monte Carlo simulation of imaging systems using these detectors, provides a means to optimize their performance in this application, as well as

R. C. Chaney; E. J. Fenyves; P. P. Antich

1990-01-01

41

A scintillating fission detector for neutron flux measurements  

SciTech Connect

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 nanocomposite-based scintillators for gamma-ray detection indicates that this approach can be extended to load nanoparticles of fissionable material into a scintillating matrix, with up to three orders of magnitude higher loading than typical fission chambers. This will result in a rugged, cost-efficient detector with high efficiency, a short signal rise time, and the ability to be used in low neutron-flux environments. Initial efforts to utilize the luminescence of uranyl oxide to eliminate the need for wavelength-shifting dyes were unsuccessful. Excitation of uranyl compounds has been reported at wavelengths ranging from 266 nm to 532 nm. However, neither the 300 nm emission of toluene, nor the 350 nm emission of PPO, nor the 410 nm emission of POPOP resulted in significant excitation of and emission by uranyl oxide. As indicated by UV/visible spectroscopy, light emitted at these wavelengths was absorbed by the colored solution. {sup 235}U remains the most attractive candidate for a fissionable scintillator, due to its high fission cross-section and lack of a threshold fission energy, but all solutions containing molecular uranium compounds will be colored, most more highly than the U{sup 6+} compounds used here. Research is therefore continuing toward the fabrication of uranium nanoparticles, in which, due to Rayleigh scattering, the coloration should be less pronounced. The characterization of the thorium-loaded liquid scintillator and the fabrication of the 100 mL detectors for use at LANSCE demonstrated the feasibility of loading fissionable material into a liquid scintillator. Analysis of beam line experiments using the thorium-loaded scintillator is underway to determine the fission event rate in the detector, for comparison with a conventional fission chamber as well as with an unloaded liquid scintillator.

Stange, Sy [Los Alamos National Laboratory; Esch, Ernst I [Los Alamos National Laboratory; Burgett, Eric A [Los Alamos National Laboratory; May, Iain [Los Alamos National Laboratory; Muenchausen, Ross E [Los Alamos National Laboratory; Taw, Felicia [Los Alamos National Laboratory; Tovesson, Fredrik K [Los Alamos National Laboratory

2010-01-01

42

Monte Carlo simulation of the data acquisition chain of scintillation detectors  

NASA Astrophysics Data System (ADS)

The good performance of a detector can be strongly affected by the instrumentation used to acquire the data. The possibility of anticipating how the acquisition chain will affect the signal can help in finding the best solution among different set-ups. In this work we developed a Monte Carlo code that aims to simulate the effect of the various components of a digital Data Acquisition system (DAQ) applied to scintillation detectors. The components included in the model are: the scintillator, the photomultiplier tube (PMT), the signal cable and the digitizer. We benchmarked the code against real data acquired with a NE213 scintillator, comparing simulated and real signal pulses induced by gamma-ray interaction. Then we studied the dependence of the energy resolution of a pulse height spectrum (PHS) on the sampling frequency and the bit resolution of the digitizer. We found that exceeding some values of the sampling frequency and the bit resolution improves only marginally the performance of the system. The method can be applied for the study of various detector systems relevant for nuclear techniques, such as in fusion diagnostics.

Binda, F.; Ericsson, G.; Hellesen, C.; Hjalmarsson, A.; Eriksson, J.; Skiba, M.; Conroy, S.; Weiszflog, M.

2014-08-01

43

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

44

Single-photoelectron noise reduction in scintillation detectors  

SciTech Connect

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

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

1995-10-01

45

Improved response function calculations for scintillation detectors using an extended version of the MCNP code  

NASA Astrophysics Data System (ADS)

The analysis of (e,e'n) experiments at the Darmstadt superconducting electron linear accelerator S-DALINAC required the calculation of neutron response functions for the NE213 liquid scintillation detectors used. In an open geometry, these response functions can be obtained using the Monte Carlo codes NRESP7 and NEFF7. However, for more complex geometries, an extended version of the Monte Carlo code MCNP exists. This extended version of the MCNP code was improved upon by adding individual light-output functions for charged particles. In addition, more than one volume can be defined as a scintillator, thus allowing the simultaneous calculation of the response for multiple detector setups. With the implementation of 12C(n,n'3?) reactions, all relevant reactions for neutron energies En<20 MeV are now taken into consideration. The results of these calculations were compared to experimental data using monoenergetic neutrons in an open geometry and a 252Cf neutron source in the complex Darmstadt setup, where in both cases excellent agreement was found.

Schweda, K.; Schmidt, D.

2002-01-01

46

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

47

Multilayer Scintillation Detector for Nuclear Physics Monitoring of Space Weather  

NASA Astrophysics Data System (ADS)

The physical characteristics of the multilayer scintillation spectrometer for identification and energy measurement of cosmic electrons, positrons and nuclei are considered in this presentation. The nuclei energy measurement range is 3-100 MeV/nucleon. This spectrometer is planning for space weather monitoring and investigation of solar-magnetospheric and geophysics effects on satellite. These characteristics were estimated by means of computer simulation. The ionization loss fluctuations, ion charge exchange during pass through detector and, especially, scintillation quenching effect (Bircs effect) were taken into account in calculations. The main results are: 1.) Ions mass identification is possible for hydrogen and helium isotopes 2.) Ions charge identification without mass identification is possible for nuclei from lithium to oxygen The preliminary estimation indicate, that including to spectrometer of thin semiconductor detector (SCD) as first layer makes possible charge identification for Z>8. This may be done by means of comparison of ion range in spectrometer with its energy loss in SCD.

Aleksandrin, Sergey; Mayorov, Andrey; Koldashov, Sergey; Batischev, Alexey; Lapushkin, Sergey; Gurov, Yury

48

Optical Scattering Lengths in Large Liquid-Scintillator Neutrino Detectors  

E-print Network

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 PXE, LAB, and Dodecane which are under discussion for next-generation experiments like SNO+, Hanohano, or LENA. Results comprise the wavelength range from 415 to 440nm. 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.

Michael Wurm; Franz von Feilitzsch; Marianne Goeger-Neff; Martin Hofmann; Tobias Lachenmaier; Timo Lewke; Teresa Marrodan Undagoitita; Quirin Meindl; Randoplh Moellenberg; Lothar Oberauer; Walter Potzel; Marc Tippmann; Sebastian Todor; Christoph Traunsteiner; Juergen Winter

2010-04-06

49

Scintillating fiber imaging detector for 14-MeV neutrons  

NASA Astrophysics Data System (ADS)

We 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 and resolution. We plan to characterize the scintillator array using 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. We describe the detector and our characterization methods, present characterization results, and give examples of the neutron images.

Ress, David B.; Lerche, Richard A.; Ellis, Raymond J.; Heaton, G. W.; Nelson, M. B.; Mant, G.; Lehr, D. E.

1994-09-01

50

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

NASA Astrophysics Data System (ADS)

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

Gopal, Arun

51

Scintillator and solid-state neutron detectors and their applications  

NASA Astrophysics Data System (ADS)

The application range of neutron detectors covers many topics, not only involving experimental research, but spanning tens of industrial, health, transport, cultural heritage fields of interest. Several studies focus on new scintillating materials where the light response, under fast and slow neutrons exposure, is triggered by proton recoil or by the presence of neutron capture materials as 10B, 6Li or 157Gd. Neutron monitors, where the robustness of silicon-based detectors can be fully exploited by coupling with suitable neutron absorber/converter materials, have recently proved their outstanding performances. Discrimination between neutron signals from other radiations, such as - or cosmic rays, is achieved through timing techniques or with pulse shape analysis. Furthermore, the choice of the detection/discrimination techniques depends on the type of application the detector will be used for. An example is Radiation Portal Monitors (RPM) for cargo inspection or luggage control that are required to satisfy specific international standards for and neutron detection efficiencies. This paper is an overview of some of the National Institute of Nuclear Physics (INFN) activities in the field of neutron detection, involving novel technologies. We will describe the most recent advances related to scintillators and silicon-based detectors coupled with thin films of suitable converters for neutron detection and we will discuss applications in the field of nuclear security.

Carturan, Sara Maria; Marchi, Tommaso; Fanchini, Erica; De Vita, Raffaella; Finocchiaro, Paolo; Pappalardo, Alfio

2014-10-01

52

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

53

Modeling scintillator-photodiodes as detectors for megavoltage CT.  

PubMed

The use of cadmium tungstate (CdWO4) and cesium iodide [CsI(Tl)] scintillation detectors is studied in megavoltage computed tomography (MVCT). A model describing the signal acquired from a scintillation detector has been developed which contains two steps: (1) the calculation of the energy deposited in the crystal due to MeV photons using the EGSnrc Monte Carlo code; and (2) the transport of the optical photons generated in the crystal voxels to photodiodes using the optical Monte Carlo code DETECT2000. The measured detector signals in single CdWO4 and CsI(Tl) scintillation crystals of base 0.275 x 0.8 cm2 and heights 0.4, 1, 1.2, 1.6 and 2 cm were, generally, in good agreement with the signals calculated with the model. A prototype detector array which contains 8 CdWO4 crystals, each 0.275 x 0.8 x 1 cm3, in contact with a 16-element array of photodiodes was built. The measured attenuation of a Cobalt-60 beam as a function of solid water thickness behaves linearly. The frequency dependent modulation transfer function [MTF(f)], noise power spectrum [NPS(f)], and detective quantum efficiency [DQE(f)] were measured for 1.25 MeV photons (in a Cobalt-60 beam). For 6 MV photons, only the MTF(f) was measured from a linear accelerator, where large pulse-to-pulse fluctuations in the output of the linear accelerator did not allow the measurement of the NPS(f). A two-step Monte Carlo simulation was used to model the detector's MTF(f), NPS(f) and DQE(f). The DQE(0) of the detector array was found to be 26% and 19% for 1.25 MeV and 6 MV photons, respectively. For 1.25 MeV photons, the maximum discrepancies between the measured and modeled MTF(f), relative NPS(f) and the DQE(f) were found to be 1.5%, 1.2%, and 1.9%, respectively. For the 6 MV beam, the maximum discrepancy between the modeled and the measured MTF(f) was found to be 2.5%. The modeling is sufficiently accurate for designing appropriate detectors for MVCT. PMID:15191313

Monajemi, T T; Steciw, S; Fallone, B G; Rathee, S

2004-05-01

54

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

55

Scintillation Crystal Detector for Low Energy Neutrino Physics  

NASA Astrophysics Data System (ADS)

A research collaboration among scientists from Taiwan, Mainland China and the United States has been set up since 1997 to initiate and pursue an experimental program in Neutrino and Astroparticle Physics. The theme of our efforts is the use of scintillating crystal detector for low-energy low-background experiments. The flagship experiment is based on CsI(Tl) crystals placed near the core of the Kuo-Sheng Nuclear Power Station in Taiwan to study low energy neutrino interactions. Various R&D projects are being pursued. A summary of our efforts and program is presented.

Wong, Henry T.; Li, Jin

56

Scintillation Crystal Detector for Low Energy Neutrino Physics  

NASA Astrophysics Data System (ADS)

A research collaboration among scientists from Taiwan, Mainland China and the United States has been built up since 1997 to initiate and pursue an experimental program in Neutrino and Astroparticle Physics. The theme of our efforts is the use of scintillating crystal detector for low-energy low-background experiments. The flagship experiment is based on CsI(Tl) crystals placed near the core of the Kuo-Sheng Nuclear Power Station in Taiwan to study low energy neutrino interactions. Various R&D projects are being pursued. A summary of our efforts and program is presented.

Wong, Henry T.; Li, Jin

2002-08-01

57

Atmospheric Neutron Measurements using a Small Scintillator Based Detector  

NASA Astrophysics Data System (ADS)

PoGOLino is a standalone scintillator-based neutron detector designed for balloon-borne missions. Its main purpose is to provide data of the neutron flux in 2 different energy ranges in the high altitude / high latitude region where the highest neutron flux in the atmosphere is found. Furthermore the influence of the Solar activity upon the neutron environment in this region is relatively strong. As a result both short and long term time fluctuations are strongest in this region. At high altitudes neutrons can form a source of background for balloon-borne scientific measurements. They can furthermore form a major source for single event upsets in electronics. A good understanding of the high altitude / high latitude neutron environment is therefore important. Measurements of the neutron environment in this region are however lacking. PoGOLino contains two 5 mm thick Lithium Calcium Aluminium Fluoride (LiCAF) scintillators used for neutron detection. The LiCAF crystals are sandwiched between 2 Bismuth Germanium Oxide (BGO) scintillating crystals, which serve to veto signals produced by gamma-rays and charged particles. The veto system makes measurements of the neutron flux possible even in high radiation environments. One LiCAF detector is shielded with polyethylene while the second remains unshielded, making the detectors sensitive in different energy ranges. The choice of a scintillator crystals as the detection material ensures a high detection efficiency while keeping the instrument small, robust and light weight. The full standalone cylindrical instrument has a radius of 120 mm, a height of 670 mm and a total mass of 13 kg, making it suitable as a piggy back mission. PoGOLino was successfully launched on March 20th 2013 from the Esrange Space Center in Northern Sweden to an altitude of 30.9 km. A detailed description of the detector design is presented, along with results of of the flight. The neutron flux measured during flight is compared to predictions based on PLANETOCOSMICS and Geant4 simulations.

Kole, Merlin; Pearce, Mark; Fukazawa, Yasushi; Fukuda, Kentaro; Ishizu, Sumito; Jackson, Miranda; Kamae, Tune; Kawaguchi, Noriaki; Kawano, Takafumi; Kiss, Mozsi; Moretti, Elena; Yanagida, Takayuki; Chauvin, Maxime; Mikhalev, Victor; Rydstrom, Stefan; Takahashi, Hiromitsu

58

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

59

Multi-layer scintillation detector for the MOON double beta decay experiment: Scintillation photon responses studied by a prototype detector MOON-1  

E-print Network

An ensemble of multi-layer scintillators is discussed as an option of the high-sensitivity detector Mo Observatory Of Neutrinos (MOON) for spectroscopic measurements of neutrino-less double beta decays. A prototype detector MOON-1, which consists of 6 layer plastic-scintillator plates, was built to study the sensitivity of the MOON-type detector. The scintillation photon collection and the energy resolution, which are key elements for the high-sensitivity experiments, are found to be 1835+/-30 photo-electrons for 976 keV electrons and sigma = 2.9+/-0.1% (dE/E = 6.8+/-0.3 % in FWHM) at the Qbb ~ 3 MeV region, respectively. The multi-layer plastic-scintillator structure with good energy resolution as well as good background suppression of beta-gamma rays is crucial for the MOON-type detector to achieve the inverted hierarchy neutrino mass sensitivity.

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

2006-09-08

60

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

61

March 4, 2013 R&D towards large-liquid scintillator detectors and measurement of  

E-print Network

kton liquid scintillator detector ~700m underground and ~60km from two nuclear power plants with ~40 includes a 5kton liquid scintillator detector ~50km from a ~17GWth power plant. Daya Bay II proposes a 20GWth power. The Institute of High Energy Physics has secured funding from the Chinese Academy

McDonald, Kirk

62

Low energy neutrino astronomy with the large liquid scintillation detector LENA  

NASA Astrophysics Data System (ADS)

The detection of low energy neutrinos in a large scintillation detector may provide further important information on astrophysical processes such as supernova physics, solar physics and elementary particle physics as well as geophysics. In this contribution, a new project for Low Energy Neutrino Astronomy (LENA) consisting of a 50 kt scintillation detector is presented.

Undagoitia, T. Marrodán; von Feilitzsch, F.; Göger-Neff, M.; Hochmuth, K. A.; Oberauer, L.; Potzel, W.; Wurm, M.

2006-07-01

63

Low energy neutrino astronomy with the large liquid-scintillation detector LENA  

NASA Astrophysics Data System (ADS)

The detection of low energy neutrinos in a large liquid scintillation detector may provide further important information on astrophysical processes as supernova physics, solar physics and elementary particle physics as well as geophysics. In this contribution, a new project for Low Energy Neutrino Astronomy (LENA) consisting of a 50 kt scintillation detector is presented.

Marrodán Undagoitia, T.; von Feilitzsch, F.; Göger-Neff, M.; Hochmuth, K. A.; Oberauer, L.; Potzel, W.; Wurm, M.

2006-05-01

64

High Energy Neutrino Physics with Liquid Scintillation Detectors John G. Learned  

E-print Network

, and these point sharply back towards the sun. But this low energy capability still has not been enough to detectHigh Energy Neutrino Physics with Liquid Scintillation Detectors John G. Learned Department scintillation detectors have been generally dedicated to low energy neutrino measure- ments, in the MeV energy

Learned, John

65

High Energy Neutrino Physics with Liquid Scintillation Detectors John G. Learned #  

E-print Network

, and these point sharply back towards the sun. But this low energy capability still has not been enough to detectHigh Energy Neutrino Physics with Liquid Scintillation Detectors John G. Learned # Department scintillation detectors have been generally dedicated to low energy neutrino measure­ ments, in the MeV energy

Learned, John

66

(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

67

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

68

A new fission-fragment detector to complement the CACTUS-SiRi setup at the Oslo Cyclotron Laboratory  

E-print Network

An array of Parallel Plate Avalanche Counters (PPAC) for the detection of heavy ions has been developed. The new device, NIFF (Nuclear Instrument for Fission Fragments), consists of four individual detectors and covers $60\\%$ of 2$\\pi$. It was designed to be used in conjunction with the SiRi array of ${\\Delta}E-E$ silicon telescopes for light charged particles and fits into the CACTUS array of 28 large-volume NaI scintillation detectors at the Oslo Cyclotron Laboratory. The low-pressure gas-filled PPACs are sensitive for the detection of fission fragments, but are insensitive to scattered beam particles of light ions or light-ion ejectiles. The PPAC detectors of NIFF have good time resolution and can be used either to select or to veto fission events in in-beam experiments with light-ion beams and actinide targets. The powerful combination of SiRi, CACTUS, and NIFF provides new research opportunities for the study of nuclear structure and nuclear reactions in the actinide region. The new setup is particularly well suited to study the competition of fission and $\\gamma$ decay as a function of excitation energy.

Tamás Gábor Tornyi; Andreas Görgen; Magne Guttormsen; Ann-Cecilie Larsen; Sunniva Siem; Attila Krasznahorkay; Lóránt Csige

2013-12-02

69

A mathematical formalism for hyperspectral, multipoint plastic scintillation detectors.  

PubMed

The aim of this paper is to generalize and extend the mathematical formalism used with plastic scintillation detectors (PSDs). By doing so, we show the feasibility of multi-point PSD. The new formalism is based on the sole hypothesis that a PSD optical signal is a linear superposition of spectra. Two calibration scenarios were developed. Both involve solving a linear equation of the form Y = XB, but the process and input data depend on the information available on the detector system. Simulations were carried out to validate both scenarios and demonstrate the advantages of the new formalism. In this paper, we prove the following results. (1) Multi-point PSDs are feasible. Simulations have shown that six different spectra could be resolved accurately even in the presence of up to 10% Gaussian noise. (2) The new formalism leads to more precise PSD measurements. (3) By using the condition number of the measurement matrix, the ideal sets of calibration measurements can be identified. (4) By using principal component analysis it was possible to identify the best set of wavelength filters. We have shown through numerical simulations that multi-point detectors are feasible. This has potential for applications such as in vivo dose verification. Furthermore, our new formalism can be used to improve the robustness and ease of use of PSDs. PMID:23060036

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

2012-11-01

70

A mathematical formalism for hyperspectral, multipoint plastic scintillation detectors  

NASA Astrophysics Data System (ADS)

The aim of this paper is to generalize and extend the mathematical formalism used with plastic scintillation detectors (PSDs). By doing so, we show the feasibility of multi-point PSD. The new formalism is based on the sole hypothesis that a PSD optical signal is a linear superposition of spectra. Two calibration scenarios were developed. Both involve solving a linear equation of the form Y = XB, but the process and input data depend on the information available on the detector system. Simulations were carried out to validate both scenarios and demonstrate the advantages of the new formalism. In this paper, we prove the following results. (1) Multi-point PSDs are feasible. Simulations have shown that six different spectra could be resolved accurately even in the presence of up to 10% Gaussian noise. (2) The new formalism leads to more precise PSD measurements. (3) By using the condition number of the measurement matrix, the ideal sets of calibration measurements can be identified. (4) By using principal component analysis it was possible to identify the best set of wavelength filters. We have shown through numerical simulations that multi-point detectors are feasible. This has potential for applications such as in vivo dose verification. Furthermore, our new formalism can be used to improve the robustness and ease of use of PSDs.

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

2012-11-01

71

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%. PMID:24875832

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

2014-01-01

72

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

73

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

74

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

75

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

76

A directional fast neutron detector using scintillating fibers and an intensified CCD camera system  

Microsoft Academic Search

We have been developing and testing a scintillating fiber detector (SFD) for use as a fast neutron sensor which can discriminate against neutrons entering at angles non-parallel to the fiber axis (``directionality''). The detector\\/convertor component is a fiber bundle constructed of plastic scintillating fibers each measuring 10 cm long and either 0.3 mm or 0.5 mm in diameter. Extensive Monte

Daniel Holslin; Anthony W. Armstrong; William Hagan; David Shreve; Scott Smith

1994-01-01

77

Large-area scintillating fiber optic neutron detector using an intensified CCD camera system  

Microsoft Academic Search

We have been developing and testing a scintillating fiber detector (SFD) for use as a fast neutron sensor which can discriminate against neutrons entering at angles non-parallel to the fiber axis (`directionality'). The detector\\/convertor component is a fiber bundle constructed of plastic scintillating fibers each measuring 10 cm long and either 0.3 mm or 0.5 mm in diameter. Extensive Monte

Daniel T. Holslin; Anthony W. Armstrong; William Hagan; David Shreve; Scott T. Smith

1994-01-01

78

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

Microsoft Academic Search

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

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

2007-01-01

79

Impact of geometry on light collection efficiency of scintillation detectors for cryogenic rare event searches  

E-print Network

Simulations of photon propagation in scintillation detectors were performed with the aim to find the optimal scintillator geometry, surface treatment, and shape of external reflector in order to achieve maximum light collection efficiency for detector configurations that avoid direct optical coupling, a situation that is commonly found in cryogenic scintillating bolometers in experimental searches for double beta decay and dark matter. To evaluate the light collection efficiency of various geometrical configurations we used the ZEMAX ray-tracing software. It was found that scintillators in the shape of a triangular prism with an external mirror shaped as truncated cone gives the highest light collection efficiency. The results of the simulations were confirmed by carrying out measurements of the light collection efficiencies of CaWO4 crystal scintillators. A comparison of simulated and measured values of light output shows good agreement

F. A. Danevich; V. V. Kobychev; R. V. Kobychev; H. Kraus; V. B. Mikhailik; V. M. Mokina; I. M. Solsky

2014-04-30

80

Impact of geometry on light collection efficiency of scintillation detectors for cryogenic rare event searches  

NASA Astrophysics Data System (ADS)

Simulations of photon propagation in scintillation detectors were performed with the aim to find the optimal scintillator geometry, surface treatment, and shape of external reflector in order to achieve maximum light collection efficiency for detector configurations that avoid direct optical coupling, a situation that is commonly found in cryogenic scintillating bolometers in experimental searches for double beta decay and dark matter. To evaluate the light collection efficiency of various geometrical configurations we used the ZEMAX ray-tracing software. It was found that scintillators in the shape of a triangular prism with an external mirror shaped as truncated cone gives the highest light collection efficiency. The results of the simulations were confirmed by carrying out measurements of the light collection efficiencies of CaWO4 crystal scintillators. A comparison of simulated and measured values of light output shows good agreement.

Danevich, F. A.; Kobychev, V. V.; Kobychev, R. V.; Kraus, H.; Mikhailik, V. B.; Mokina, V. M.; Solsky, I. M.

2014-10-01

81

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

82

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

83

Performance of liquid argon neutrino detectors with enhanced sensitivity to scintillation light  

E-print Network

Scintillation light is used in liquid argon neutrino detectors to provide a trigger signal, veto information against cosmic rays, and absolute event timing. In this work, we discuss additional opportunities offered by detectors with enhanced sensitivity to scintillation light, that is with light collection efficiencies of about $10^{-3}$. We focus on two key detector performance indicators for neutrino oscillation physics: calorimetric neutrino energy reconstruction and neutrino/antineutrino separation in a non-magnetized detector. Our simulations indicate that a neutrino energy resolution as good as 3.3\\% RMS for 4 GeV electron neutrino charged-current interactions can in principle be obtained in a large detector of this type, by using both charge and light information. By exploiting muon capture in argon and scintillation light information to veto muon decay electrons, we also obtain muon neutrino identification efficiencies of about 50\\%, and muon antineutrino misidentification rates at the few percent lev...

Sorel, M

2014-01-01

84

Detection of energetic particles and gamma rays Scintillation detectors  

E-print Network

· unactivated slow · Tl-activated · Ce-activated · glass #12;11 Unactivated fast inorganic scintillators · fast inorganic scintillators · BGO (bismuth germanate, Bi4Ge3O16) ­ very high Z · CdWO4 (cadmium tungstate) · Pb

Peletier, Reynier

85

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

86

Continuous Scintillator Detector Blocks for Simultaneous Pet-Mr Imaging of the Human Brain  

NASA Astrophysics Data System (ADS)

Continuous scintillator detector blocks have several advantages over pixelated designs, presenting a larger active volume and a lower cost with comparable or better energy and spatial resolutions. In this paper we describe the operation of continuous detector blocks for positron emission tomography (PET) and their suitability for multimodality imaging operating inside a magnetic resonance (MR) scanner. This detector technology is being used on a full-scale clinical scanner for human brain PET studies presently under development at Ciemat. Results will be presented on the laboratory characterization of monolithic scintillators coupled to APD matrices with ASIC readout, including images of point sources from a prototype dual-head demonstrator illustrating the potential of continuous scintillator detector blocks for high-resolution PET-MR imaging.

Rato Mendes, Pedro

2010-04-01

87

Photonic Crystals: Enhancing the Light Output of Scintillation Based Detectors  

E-print Network

A scintillator is a material which emits light when excited by ionizing radiation. Such materials are used in a diverse range of applications; From high energy particle physics experiments, X-ray security, to nuclear cameras or positron emission tomography. Future high-energy physics (HEP) experiments as well as next generation medical imaging applications are more and more pushing towards better scintillation characteristics. One of the problems in heavy scintillating materials is related to their high index of refraction. As a consequence, most of the scintillation light produced in the bulk material is trapped inside the crystal due to total internal reflection. The same problem also occurs with light emitting diodes (LEDs) and has for a long time been considered as a limiting factor for their overall efficiency. Recent developments in the area of nanophotonics were showing now that those limitations can be overcome by introducing a photonic crystal (PhC) slab at the outcoupling surface of the substrate. P...

Knapitsch, Arno Richard

88

Advanced Scintillator Detector Concept (ASDC): A Concept Paper on the Physics Potential of Water-Based Liquid Scintillator  

E-print Network

The recent development of Water-based Liquid Scintillator (WbLS), and the concurrent development of high-efficiency and high-precision-timing light sensors, has opened up the possibility for a new kind of large-scale detector capable of a very broad program of physics. The program would include determination of the neutrino mass hierarchy and observation of CP violation with long-baseline neutrinos, searches for proton decay, ultra-precise solar neutrino measurements, geo- and supernova neutrinos including diffuse supernova antineutrinos, and neutrinoless double beta decay. We outline here the basic requirements of the Advanced Scintillation Detector Concept (ASDC), which combines the use of WbLS, doping with a number of potential isotopes for a range of physics goals, high efficiency and ultra-fast timing photosensors, and a deep underground location. We are considering such a detector at the Long Baseline Neutrino Facility (LBNF) far site, where the ASDC could operate in conjunction with the liquid argon tracking detector proposed by the LBNE collaboration. The goal is the deployment of a 30-100 kiloton-scale detector, the basic elements of which are being developed now in experiments such as WATCHMAN, ANNIE, SNO+, and EGADS.

J. R. Alonso; N. Barros; M. Bergevin; A. Bernstein; L. Bignell; E. Blucher; F. Calaprice; J. M. Conrad; F. B. Descamps; M. V. Diwan; D. A. Dwyer; S. T. Dye; A. Elagin; P. Feng; C. Grant; S. Grullon; S. Hans; D. E. Jaffe; S. H. Kettell; J. R. Klein; K. Lande; J. G. Learned; K. B. Luk; J. Maricic; P. Marleau; A. Mastbaum; W. F. McDonough; L. Oberauer; G. D. Orebi Gann; R. Rosero; S. D. Rountree; M. C. Sanchez; M. H. Shaevitz; T. M. Shokair; M. B. Smy; A. Stahl; M. Strait; R. Svoboda; N. Tolich; M. R. Vagins; K. A. van Bibber; B. Viren; R. B. Vogelaar; M. J. Wetstein; L. Winslow; B. Wonsak; E. T. Worcester; M. Wurm; M. Yeh; C. Zhang

2014-09-20

89

Theory of the field-controlled scintillation detector  

Microsoft Academic Search

It is shown theoretically that application of an external electromagnetic field with specially selected frequencies in a dielectric\\u000a containing impurity atoms allows a scintillation process of emission from impurity atoms to be activated which does not involve\\u000a phonons. The process is similar to that in a conventional scintillator except that the field is completely controlled. The\\u000a behavior of the emission

M. I. Ryazanov

1999-01-01

90

Calibration of the NaI(Tl) detector set-up used to study natural stone countertops  

E-print Network

Calibration of the NaI(Tl) detector set-up used to study natural stone countertops W.J. Llope Rice measurements of the spectra from natural stone countertops is described in this note. The basic set-up consists the 22 Na source with the collection of data from the stone sample of interest. The energy calibration

Llope, William J.

91

In-situ calibration of a PMT inside a scintillation detector by means of primary scintillation detection  

E-print Network

We have investigated the possibility of calibrating the PMTs of scintillation detectors, using the primary scintillation produced by X-rays to induce single photoelectron response of the PMT. The high-energy tail of this response, can be approximated to an exponential function, under some conditions. In these cases, it is possible to determine the average gain for each PMT biasing voltage from the inverse of the exponent of the exponential fit to the tail, which can be done even if the background and/or noise cover-up most of the distribution. We have compared our results with those obtained by the commonly used single electron response (SER) method, which uses a LED to induce a single photoelectron response of the PMT and determines the peak position of such response, relative to the pedestal peak (the electronic noise peak, which corresponds to 0 photoelectrons). The results of the exponential fit method agree with those obtained by the SER method when the average number of photoelectrons reaching the first dynode per light/scintillation pulse is around 1.0. The SER method has higher precision, while the exponential fit method has the advantage of being useful in situations where the PMT is already in situ, being difficult or even impossible to apply the SER method, e.g. in sealed scintillator/PMT devices.

NEXT Collaboration; V. Álvarez; F. I. G. M. Borges; S. Cárcel; J. Castel; S. Cebrián; A. Cervera; C. A. N. Conde; T. Dafni; T. H. V. T. Dias; J. Díaz; M. Egorov; R. Esteve; P. Evtoukhovitch; L. M. P. Fernandes; P. Ferrario; A. L. Ferreira; E. D. C. Freitas; V. M. Gehman; A. Gil; A. Goldschmidt; H. Gómez; J. J. Gómez-Cadenas; D. González-Díaz; R. M. Gutiérrez; J. Hauptman; J. A. Hernando Morata; D. C. Herrera; F. J. Iguaz; I. G. Irastorza; M. A. Jinete; L. Labarga; A. Laing; I. Liubarsky; J. A. M. Lopes; D. Lorca; M. Losada; G. Luzón; A. Marí; J. Martín-Albo; A. Martínez; T. Miller; A. Moiseenko; F. Monrabal; C. M. B. Monteiro; F. J. Mora; L. M. Moutinho; J. Muñoz Vidal; H. Natal da Luz; G. Navarro; M. Nebot; D. Nygren; C. A. B. Oliveira; R. Palma; J. Pérez; J. L. Pérez Aparicio; J. Renner; L. Ripoll; A. Rodríguez; J. Rodríguez; F. P. Santos; J. M. F. dos Santos; L. Segui; L. Serra; D. Shuman; A. Simón; C. Sofka; M. Sorel; J. F. Toledo; A. Tomás; J. Torrent; Z. Tsamalaidze; D. Vázquez; J. F. C. A. Veloso; J. A. Villar; R. C. Webb; J. T White; N. Yahlali

2012-11-19

92

Water-Equivalent Plastic Scintillation Detectors for High-Energy Photon and Electron Beams  

NASA Astrophysics Data System (ADS)

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 fiber bundles, each connected to independent photomultiplier tubes (PMT). One fiber bundle is connected to a miniature water-equivalent scintillator and so scintillation as well as Cerenkov light generated in the fibers is detected at its PMT. The other "background" bundle is not connected to the scintillator and so only Cerenkov is detected by its PMT. The background signal is subtracted to yield only the signal from the scintillator. The dose distribution in water is measured using these plastic scintillation detectors for different high -energy photon and electron beams. Excellent agreement is obtained when compared to ionization chambers and silicon diodes. The most important properties of the system are its high spatial resolution (0.003 cc) and its nearly water -equivalence. It is shown that they have better spatial resolution than ion chambers, require no replacement correction in phantoms, have less energy dependence than Si diodes in x-ray beams, have much less energy (or depth) dependence than ion chambers in electron fields, and less perturbation of either x-ray or electron beams than either Si diodes or ion chambers. Their other strength lies in their use for field mapping in water phantoms, or in-vivo insertions.

Beddar, Abdou-Samad

1990-01-01

93

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

94

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

PubMed Central

Designing a plastic scintillation detector for proton radiation therapy requires careful consideration. Most plastic scintillators should not perturb a proton beam if they are sufficiently small but may exhibit some energy dependence due to 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. 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 a 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

2014-01-01

95

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

96

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

PubMed

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. PMID:18695295

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

2008-09-01

97

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

98

Multi-sector scintillation detector for investigations of extensive air showers  

NASA Astrophysics Data System (ADS)

A new type of scintillation detector for shower arrays is considered. The detector represents an octagonal scintillation assembly with total area 1 m 2 divided into sectors. Thickness of the plastic is 20 mm. The light is collected by wavelength shifter bars to the photomultiplier, which is located in the center of the detector. A solution to ensure the uniformity of light collection for any coordinate is proposed. Front-end electronics of the detector consists of the controller, the measuring part (QDC, TDC), the system of calibration and the HV converter. The data acquisition system is based on CAN-open standard. There is also a system of temperature stabilization that guarantees not more than 0.5° deviation of the temperature of measuring part elements. Measuring electronics allows obtaining the dynamic range from 1 up to 10 4 particles and 1 ns time digitization. The time resolution of the detector is about 3 ns.

Yanson, E. E.; Denisov, S. P.; Gilitsky, Yu. V.; Kindin, V. V.; Kokoulin, R. P.; Kompaniets, K. G.; Lipaev, V. V.; Matyushin, A. A.; Ovchinnikov, A. V.; Petrukhin, A. A.; Prokopenko, N. N.; Soldatov, M. M.; Sytin, A. N.

2009-01-01

99

A wavelength-shifting-fibre-based scintillator neutron detector implemented with the median point calculation method  

NASA Astrophysics Data System (ADS)

Median point calculation (MPC) method for scintillator neutron detectors operating in photon-counting mode has been developed. The method was applied to a wavelength-shifting (WLS)-fibre-based neutron detector in order to improve its pixel size and spatial resolution. The original detector was modified for a demonstration experiment performed using the SENJU neutron diffraction instrument at J-PARC (Japan Proton Accelerator Research Complex). The detector head comprised 64 × 2 WLS fibres arranged in the x and y directions at a pitch of 4 mm. The WLS fibres were sandwiched between two ZnS/10B2O3 scintillator screens. The developed MPC method used the number of photons detected by each WLS fibre as a weight when calculating the positions of neutrons. The test detector implemented with the MPC method demonstrated that the effective pixel size and the spatial resolution were improved to 2 mm, corresponding to half the pitch of the WLS fibres.

Nakamura, T.; Kawasaki, T.; Hosoya, T.; Toh, K.; Ebine, M.; Birumachi, A.; Sakasai, K.; Soyama, K.; Katagiri, M.

2012-02-01

100

PoGOLino: a scintillator-based balloon-borne neutron detector  

E-print Network

PoGOLino is a balloon-borne scintillator-based experiment developed to study the largely unexplored high altitude neutron environment at high geomagnetic latitudes. The instrument comprises two detectors that make use of LiCAF, a novel neutron sensitive scintillator, sandwiched by BGO crystals for background reduction. The experiment was launched on March 20th 2013 from the Esrange Space Centre, Northern Sweden (geomagnetic latitude of $65^\\circ$), for a three hour flight during which the instrument took data up to an altitude of 30.9 km. The detector design and ground calibration results are presented together with the measurement results from the balloon flight.

Kole, Merlin; Fukazawa, Yasushi; Fukuda, Kentaro; Ishizu, Sumito; Jackson, Miranda; Kamae, Tune; Kawaguchi, Noriaki; Kawano, Takafumi; Kiss, Mozsi; Moretti, Elena; Pearce, Mark; Rydström, Stefan; Takahashi, Hiromitsu; Yanagida, Takayuki

2014-01-01

101

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

NASA Astrophysics Data System (ADS)

The 144 detector modules comprising the Large-area multi-Institutional Scintillator Array (LISA) neutron detector were tested at each of the nine primarily undergraduate institutions. Each module is a 200 cm by 10 cm by 10 cm bar of EJ-200 organic plastic scintillator a with a photomultiplier tube mounted on each end. We used cosmic rays both to ensure that each module was light tight as well as to characterize position and time resolution. In addition, we measured each module's light attenuation using gamma sources. Results will be presented.

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

2010-11-01

102

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

103

Liquid scintillators for large mass and low background detectors  

Microsoft Academic Search

The attenuation length of liquid scintillator mixtures suitable for large scale and low background experiments like Borexino is measured. Attenuation leghths of the order of some metres have been obtained by a careful control of the purity and cleanliness of the components. The possible contribution of processes of radiative transport is discussed.

F. Gatti; G. Morelli; G. Testera; S. Vitale

1996-01-01

104

SENTIRAD—An innovative personal radiation detector based on a scintillation detector and a silicon photomultiplier  

NASA Astrophysics Data System (ADS)

The alarming personal radiation detector (PRD) is a device intended for Homeland Security (HLS) applications. This portable device is designed to be worn or carried by security personnel to detect photon-emitting radioactive materials for the purpose of crime prevention. PRD is required to meet the scope of specifications defined by various HLS standards for radiation detection. It is mandatory that the device be sensitive and simultaneously small, pocket-sized, of robust mechanical design and carriable on the user's body. To serve these specialized purposes and requirements, we developed the SENTIRAD, a new radiation detector designed to meet the performance criteria established for counterterrorist applications. SENTIRAD is the first commercially available PRD based on a CsI(Tl) scintillation crystal that is optically coupled with a silicon photomultiplier (SiPM) serving as a light sensor. The rapidly developing technology of SiPM, a multipixel semiconductor photodiode that operates in Geiger mode, has been thoroughly investigated in previous studies. This paper presents the design considerations, constraints and radiological performance relating to the SENTIRAD radiation sensor.

Osovizky, A.; Ginzburg, D.; Manor, A.; Seif, R.; Ghelman, M.; Cohen-Zada, I.; Ellenbogen, M.; Bronfenmakher, V.; Pushkarsky, V.; Gonen, E.; Mazor, T.; Cohen, Y.

2011-10-01

105

Advanced Scintillator Detector Concept (ASDC): A Concept Paper on the Physics Potential of Water-Based Liquid Scintillator  

E-print Network

The recent development of Water-based Liquid Scintillator (WbLS), and the concurrent development of high-efficiency and high-precision-timing light sensors, has opened up the possibility for a new kind of large-scale detector capable of a very broad program of physics. The program would include determination of the neutrino mass hierarchy and observation of CP violation with long-baseline neutrinos, searches for proton decay, ultra-precise solar neutrino measurements, geo- and supernova neutrinos including diff?use supernova antineutrinos, and neutrinoless double beta decay. We outline here the basic requirements of the Advanced Scintillation Detector Concept (ASDC), which combines the use of WbLS, doping with a number of potential isotopes for a range of physics goals, high efficiency and ultra-fast timing photosensors, and a deep underground location. We are considering such a detector at the Long Baseline Neutrino Facility (LBNF) far site, where the ASDC could operate in conjunction with the liquid argon t...

Alonso, J R; Bergevin, M; Bernstein, A; Bignell, L; Blucher, E; Calaprice, F; Conrad, J M; Descamps, F B; Diwan, M V; Dwyer, D A; Dye, S T; Elagin, A; Feng, P; Grant, C; Grullon, S; Hans, S; Jaffe, D E; Kettell, S H; Klein, J R; Lande, K; Learned, J G; Luk, K B; Maricic, J; Marleau, P; Mastbaum, A; McDonough, W F; Oberauer, L; Gann, G D Orebi; Rosero, R; Rountree, S D; Sanchez, M C; Shaevitz, M H; Shokair, T M; Smy, M B; Strait, M; Svoboda, R; Tolich, N; Vagins, M R; van Bibber, K A; Viren, B; Vogelaar, R B; Wetstein, M J; Winslow, L; Wonsak, B; Worcester, E T; Wurm, M; Yeh, M; Zhang, C

2014-01-01

106

Expected performance of an ideal liquid argon neutrino detector with enhanced sensitivity to scintillation light  

NASA Astrophysics Data System (ADS)

Scintillation light is used in liquid argon (LAr) neutrino detectors to provide a trigger signal, veto information against cosmic rays, and absolute event timing. In this work, we discuss additional opportunities offered by detectors with enhanced sensitivity to scintillation light, that is with light collection efficiencies of about 10-3. We focus on two key detector performance indicators for neutrino oscillation physics: calorimetric neutrino energy reconstruction and neutrino/antineutrino separation in a non-magnetized detector. Our results are based on detailed simulations, with neutrino interactions modelled according to the GENIE event generator, while the charge and light responses of a large LAr ideal detector are described by the Geant4 and NEST simulation tools. A neutrino energy resolution as good as 3.3% RMS for 4 GeV electron neutrino charged-current interactions can in principle be obtained in a large detector of this type, by using both charge and light information. By exploiting muon capture in argon and scintillation light information to veto muon decay electrons, we also obtain muon neutrino identification efficiencies of about 50%, and muon antineutrino misidentification rates at the few percent level, for few-GeV neutrino interactions that are fully contained. We argue that the construction of large LAr detectors with sufficiently high light collection efficiencies is in principle possible.

Sorel, M.

2014-10-01

107

Expected performance of an ideal liquid argon neutrino detector with enhanced sensitivity to scintillation light  

E-print Network

Scintillation light is used in liquid argon (LAr) neutrino detectors to provide a trigger signal, veto information against cosmic rays, and absolute event timing. In this work, we discuss additional opportunities offered by detectors with enhanced sensitivity to scintillation light, that is with light collection efficiencies of about $10^{-3}$. We focus on two key detector performance indicators for neutrino oscillation physics: calorimetric neutrino energy reconstruction and neutrino/antineutrino separation in a non-magnetized detector. Our results are based on detailed simulations, with neutrino interactions modelled according to the GENIE event generator, while the charge and light responses of a large LAr ideal detector are described by the Geant4 and NEST simulation tools. A neutrino energy resolution as good as 3.3\\% RMS for 4 GeV electron neutrino charged-current interactions can in principle be obtained in a large detector of this type, by using both charge and light information. By exploiting muon capture in argon and scintillation light information to veto muon decay electrons, we also obtain muon neutrino identification efficiencies of about 50\\%, and muon antineutrino misidentification rates at the few percent level, for few-GeV neutrino interactions that are fully contained. We argue that the construction of large LAr detectors with sufficiently high light collection efficiencies is in principle possible.

M. Sorel

2014-05-05

108

Novel CT detector based on an inorganic scintillator working in photon-counting mode  

NASA Astrophysics Data System (ADS)

Detectors working in photon counting mode offer an interesting alternative to the common charge integrating detectors for computed tomography (CT), because they can potentially measure the energy of every detected X-ray photons and achieve better image contrast sensitivity for a given dose. Unfortunately, most current X-ray detectors suffer from limited count rate capability, due either to a long charge migration time in semiconductor and gas detectors, or to a slow decay time in ceramic scintillators. To overcome these difficulties, we propose to use pixel detectors based on fast light emitting inorganic scintillators individually coupled to avalanche photodiodes with parallel, low-noise, fast digital processing electronics to provide real time single event detection and recording. The proposed detector was investigated with 2 × 2 × 10 mm 3 Lu 1.9Y 0.1SiO 5 (LYSO), a fast decay time (40 ns), heavy (7.19 g/cc) scintillator that is also suitable for coincidence detection of annihilation radiation (511 keV) in positron emission tomography (PET). Therefore, the detector characteristics make it a good candidate for implementation in a combined PET/CT dual-modality scanner. Although only coarse spectral analysis is possible in the X-ray energy range, it is demonstrated that appropriate CT images for anatomical localization can be obtained at very low dose in counting mode using a PET/CT simulator set up for small animal imaging. Data are reported on CT image resolution, noise, contrast and dose.

Bérard, Philippe; Riendeau, Joël; Pepin, Catherine M.; Rouleau, Daniel; Cadorette, Jules; Fontaine, Réjean; Lecomte, Roger

2006-03-01

109

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

110

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

SciTech Connect

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

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

2010-02-15

111

The Effect of Neutron and Gamma Ray Cross Talk Between Plastic Scintillating Detectors  

SciTech Connect

In this paper a method is developed, using higher order statistics, to identify the type and degree of neutron and gamma ray cross talk between detectors that are placed in proximity to one another. A set of measurements was performed using the Nuclear Materials Identification System (NMIS) to acquire the time-dependent bicovariance of the pulses in fast plastic scintillating detectors. These signatures were analyzed to infer the degree and type of false coincidences (cross talk) in relation to true coincidences.

Pozzi, S.A.

2000-11-06

112

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

113

NUTSPEC: a program for unfolding neutron spectral data obtained with scintillation detectors and gas proportional counters  

Microsoft Academic Search

NUTSPEC, an interactive program available on the LLL CDC 7600 Octopus Network computers, unfolds neutron spectral data obtained with NE213 and stilbene scintillation detectors, as well as CH, H, and ³He gas proportional counters. This document explains how to obtain and execute the program, and describes the input and output data formats used by NUTSPEC. Examples of input files and

Slaughter

1978-01-01

114

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

115

Probing the Earth's interior with a large-volume liquid scintillator detector  

E-print Network

A future large-volume liquid scintillator detector would provide a high-statistics measurement of terrestrial antineutrinos originating from $\\beta$-decays of the uranium and thorium chains. In addition, the forward displacement of the neutron in the detection reaction $\\bar\

Kathrin A. Hochmuth; Franz v. Feilitzsch; Brian D. Fields; Teresa Marrodan Undagoitia; Lothar Oberauer; Walter Potzel; Georg G. Raffelt; Michael Wurm

2005-09-13

116

Development of a 3D position sensitive scintillation detector using neural networks  

Microsoft Academic Search

This work presents a novel method of exploiting light division in a scintillating crystal to localise in three-dimensions the point of interaction of an impinging photon. For this, light output of a detector block is mapped for known irradiation positions of a collimated photon beam and used to train a set of three independent multilayer neural networks. Spatial resolutions obtained

D. Clement; R. Frei; J.-F. Loude; C. Morel

1998-01-01

117

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

118

Extracting light from a scintillator detector using a one dimensional dielectric structure  

E-print Network

loss is reflection due to the refractive index difference between the two media[1]. Significantly the scintillator has a higher refractive index than the attached detector resulting in total reflection beyond will alter the reflection and refraction properties of the surface. By appropriate selection of refractive

Haddadi, Hamed

119

Probing the Earth’s interior with a large-volume liquid scintillator detector  

NASA Astrophysics Data System (ADS)

A future large-volume liquid scintillator detector would provide a high-statistics measurement of terrestrial antineutrinos originating from ?-decays of the uranium and thorium chains. In addition, the forward displacement of the neutron in the detection reaction ?+p?n+e provides directional information. We investigate the requirements on such detectors to distinguish between certain geophysical models on the basis of the angular dependence of the geoneutrino flux. Our analysis is based on a Monte-Carlo simulation with different levels of light yield, considering both unloaded and gadolinium-loaded scintillators. We find that a 50 kt detector such as the proposed LENA (Low Energy Neutrino Astronomy) will detect deviations from isotropy of the geoneutrino flux significantly. However, with an unloaded scintillator the time needed for a useful discrimination between different geophysical models is too large if one uses the directional information alone. A Gd-loaded scintillator improves the situation considerably, although a 50 kt detector would still need several decades to distinguish between a geophysical reference model and one with a large neutrino source in the Earth’s core. However, a high-statistics measurement of the total geoneutrino flux and its spectrum still provides an extremely useful glance at the Earth’s interior.

Hochmuth, Kathrin A.; Feilitzsch, Franz V.; Fields, Brian D.; Undagoitia, Teresa Marrodán; Oberauer, Lothar; Potzel, Walter; Raffelt, Georg G.; Wurm, Michael

2007-02-01

120

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

SciTech Connect

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

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

2011-12-13

121

Neutron emission measurement at the HL-2A tokamak device with a liquid scintillation detector  

NASA Astrophysics Data System (ADS)

Neutron emission measurement at the HL-2A tokamak device with a liquid scintillation detector is described. The detector was placed at a location with little structure material in the field of view, and equipped with a gain monitoring system which could provide the possibility to evaluate the gain variation as well as to correct for the detector response. Time trace of the neutron emissivity was obtained and it was consistent with the result of a standard 235U fission chamber. During the plasma discharge the neutron yield could vary by about four orders of magnitude and the fluctuation of the detector gain was up to about 6%. Pulse height spectrum of the liquid scintillation detector was constructed and corrected with the aid of the gain monitoring system, and the correction was found to be essential for the assessment of the neutron energy spectrum. This successful measurement offered experience and confidence for the application of liquid scintillation detectors in the upcoming neutron camera system.

Xie, Xufei; Chen, Zhongjing; Peng, Xingyu; Yuan, Xi; Zhang, Xing; Gorini, Giuseppe; Cui, Zhiqiang; Du, Tengfei; Hu, Zhimeng; Li, Tao; Fan, Tieshuan; Chen, Jinxiang; Li, Xiangqing; Zhang, Guohui; Yuan, Guoliang; Yang, Jinwei; Yang, Qingwei

2014-10-01

122

Neutron emission measurement at the HL-2A tokamak device with a liquid scintillation detector.  

PubMed

Neutron emission measurement at the HL-2A tokamak device with a liquid scintillation detector is described. The detector was placed at a location with little structure material in the field of view, and equipped with a gain monitoring system which could provide the possibility to evaluate the gain variation as well as to correct for the detector response. Time trace of the neutron emissivity was obtained and it was consistent with the result of a standard (235)U fission chamber. During the plasma discharge the neutron yield could vary by about four orders of magnitude and the fluctuation of the detector gain was up to about 6%. Pulse height spectrum of the liquid scintillation detector was constructed and corrected with the aid of the gain monitoring system, and the correction was found to be essential for the assessment of the neutron energy spectrum. This successful measurement offered experience and confidence for the application of liquid scintillation detectors in the upcoming neutron camera system. PMID:25362392

Xie, Xufei; Chen, Zhongjing; Peng, Xingyu; Yuan, Xi; Zhang, Xing; Gorini, Giuseppe; Cui, Zhiqiang; Du, Tengfei; Hu, Zhimeng; Li, Tao; Fan, Tieshuan; Chen, Jinxiang; Li, Xiangqing; Zhang, Guohui; Yuan, Guoliang; Yang, Jinwei; Yang, Qingwei

2014-10-01

123

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

124

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

125

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

126

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. PMID:23180976

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

2012-01-01

127

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

PubMed

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

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

2012-10-01

128

Fast Neutron Detector for Fusion Reactor KSTAR Using Stilbene Scintillator  

E-print Network

Various neutron diagnostic tools are used in fusion reactors to evaluate different aspects of plasma performance, such as fusion power, power density, ion temperature, fast ion energy, and their spatial distributions. The stilbene scintillator has been proposed for use as a neutron diagnostic system to measure the characteristics of neutrons from the Korea Superconducting Tokamak Advanced Research (KSTAR) fusion reactor. Specially designed electronics are necessary to measure fast neutron spectra with high radiation from a gamma-ray background. The signals from neutrons and gamma-rays are discriminated by the digital charge pulse shape discrimination (PSD) method, which uses total to partial charge ratio analysis. The signals are digitized by a flash analog-to-digital convertor (FADC). To evaluate the performance of the fabricated stilbene neutron diagnostic system, the efficiency of 10 mm soft-iron magnetic shielding and the detection efficiency of fast neutrons were tested experimentally using a 252Cf neutr...

Lee, Seung Kyu; Kim, Gi-Dong; Kim, Yong-Kyun

2011-01-01

129

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

PubMed

A coincidence system using a plastic scintillator detector in 4pi 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) scintillation counter. The electronic system for processing pulses consisted of logic gates and delay modules feeding a time-to-amplitude converter with output to a multichannel analyzer. The alpha detection efficiency measured with 241Am was around 95% and the beta detection efficiency for 60Co was around 67%. Activity measurements of 241Am and 60Co were performed and the results showed good agreement when compared with a conventional coincidence system employing a 4pi proportional counter. PMID:12573324

Baccarelli, Aída M; Dias, Mauro S; Koskinas, Marina F

2003-02-01

130

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

131

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

132

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

133

Fast Neutron Detector for Fusion Reactor KSTAR Using Stilbene Scintillator  

E-print Network

Various neutron diagnostic tools are used in fusion reactors to evaluate different aspects of plasma performance, such as fusion power, power density, ion temperature, fast ion energy, and their spatial distributions. The stilbene scintillator has been proposed for use as a neutron diagnostic system to measure the characteristics of neutrons from the Korea Superconducting Tokamak Advanced Research (KSTAR) fusion reactor. Specially designed electronics are necessary to measure fast neutron spectra with high radiation from a gamma-ray background. The signals from neutrons and gamma-rays are discriminated by the digital charge pulse shape discrimination (PSD) method, which uses total to partial charge ratio analysis. The signals are digitized by a flash analog-to-digital convertor (FADC). To evaluate the performance of the fabricated stilbene neutron diagnostic system, the efficiency of 10 mm soft-iron magnetic shielding and the detection efficiency of fast neutrons were tested experimentally using a 252Cf neutron source. In the results, the designed and fabricated stilbene neutron diagnostic system performed well in discriminating neutrons from gamma-rays under the high magnetic field conditions during KSTAR operation. Fast neutrons of 2.45 MeV were effectively measured and evaluated during the 2011 KSTAR campaign.

Seung Kyu Lee; Byoung-Hwi Kang; Gi-Dong Kim; Yong-Kyun Kim

2011-12-27

134

Scintillator-photodiode type detectors for multi-energy scanning introscopy  

E-print Network

Results of experimental studies of detector arrays S-PD (scintillator-photodiode) and PRD (scintillator-photoreceiving device) used for X-ray digital radiography have shown that there exist further possibilities to increase spatial resolution of this system up to 2-3 line pairs per mm. Theoretical analysis and experimental studies show that the two-energy detection method not only allows one to detect organics on the background of metal, but also substantially increases (by 3-5 times) the detection ability of the system as a whole, especially if parameters of the S-PD pair are optimized, in particular, when ZnSe(Te) is used in the low-energy circuit. A possibility to distinguish, in principle, between substances with insignificant differences in atomic number has been theoretically proven -- by transition to multi-energy radiography. 3D-imaging has been realized using S-PD detector arrays.

Ryzhikov, V D; Kozin, D N; Lisetskaya, E K; Opolonin, A D; Svishch, V M; Kulik, T V

2002-01-01

135

Scintillator-photodiode type detectors for multi-energy scanning introscopy  

E-print Network

Results of experimental studies of detector arrays S-PD (scintillator-photodiode) and PRD (scintillator-photoreceiving device) used for X-ray digital radiography have shown that there exist further possibilities to increase spatial resolution of this system up to 2-3 line pairs per mm. Theoretical analysis and experimental studies show that the two-energy detection method not only allows one to detect organics on the background of metal, but also substantially increases (by 3-5 times) the detection ability of the system as a whole, especially if parameters of the S-PD pair are optimized, in particular, when ZnSe(Te) is used in the low-energy circuit. A possibility to distinguish, in principle, between substances with insignificant differences in atomic number has been theoretically proven -- by transition to multi-energy radiography. 3D-imaging has been realized using S-PD detector arrays.

V. D. Ryzhikov; S. V. Naydenov; D. N. Kozin; E. K. Lisetskaya; A. D. Opolonin; V. M. Svishch; T. V. Kulik

2002-07-23

136

Response matrices of NE213 scintillation detectors for neutrons  

SciTech Connect

Four NE213 detectors of different size have been calibrated at the accelerator facility of the PTB. The response functions were experimentally determined for 33 neutron energies between 1 MeV and 16 MeV and compared with Monte Carlo simulations using the NRESP7 code. The light output functions for recoil protons were found to be significantly different for all detectors even if they were of the same size. The neutron fluence determined on the basis of the response functions calculated with the corresponding light output functions agreed to better than {+-}2% with reference values if energy independent adjustment factors between 0.98 and 1.03 were applied. The response matrices required for the unfolding of neutron induced pulse height spectra were therefore calculated with the NRESP7 code taking into account the adjustment factors. Similarly, the response matrices for photons were calculated with the EGS4 code, but without any adjustment. Finally, the DIFBAS code was applied for the unfolding of pure neutron- and photon-induced pulse height spectra. The resulting spectral fluences are in reasonable agreement with the results obtained by time-of-flight measurements and by spectrometry with a Ge detector.

Guldbakke, S.; Klein, H. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Meister, A.; Scheler, U.; Unholzer, S. [Technical Univ., Dresden (Germany); Pulpan, J.; Tichy, M. [Inst. of Radiation Dosimetry, Prague (Czech Republic)

1994-12-31

137

Monte Carlo analysis of neutron detection with a BaF2 scintillation detector  

Microsoft Academic Search

This work presents the results of investigations aimed at simulating the response of a barium fluoride (BaF2) detector to neutrons and photons. The simulations are performed with the MCNP-PoliMi code, a modification of MCNP-4C. The simulation results are compared to time-of-flight measurements performed with the nuclear materials identification system (NMIS). In particular, the neutron detection capabilities of the BaF2 scintillator

Sara A. Pozzi; John S. Neal; Richard B. Oberer; John T. Mihalczo

2004-01-01

138

Characterization of a scintillating GEM detector with low energy x-rays.  

PubMed

A two-dimensional position-sensitive dosimetry system based on a scintillating gas detector is being developed with the aim of using it for pre-treatment verification of dose distributions in charged particle therapy. The dosimetry system consists of a chamber filled with an Ar/CF(4) 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. In such a system, light quanta are emitted by the scintillating gas mixture during the electron avalanches in the GEM holes when radiation traverses the detector. The light intensity distribution is proportional to the energy deposited in the detector's sensitive volume by the beam. In the present work, we investigated the optimization of the scintillating GEM detector light yield. The light quanta are detected by means of a CCD camera or a photomultiplier tube coupled to a monochromator. The GEM charge signal is measured simultaneously. We have found that with 60 microm diameter double conical GEM holes, a brighter light signal and a higher electric signal are obtained than with 80 microm diameter holes. With an Ar + 8% CF(4) volume concentration, the highest voltage across the GEMs and the largest light and electric signals were reached. Moreover, we have found that the emission spectrum of Ar/CF(4) is independent of (1) the voltages applied across the GEMs, (2) the x-ray beam intensity and (3) the GEM hole diameter. On the other hand, the ratio of Ar to CF(4) peaks in the spectrum changes when the concentration of the latter gas is varied. PMID:18854612

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

2008-11-01

139

Detection potential for the diffuse supernova neutrino background in the large liquid-scintillator detector LENA  

NASA Astrophysics Data System (ADS)

The large-volume liquid-scintillator detector LENA (low energy neutrino astronomy) will provide high-grade background discrimination and enable the detection of diffuse supernova neutrinos (DSN) in an almost background-free energy window from ˜10 to 25 MeV. Within ten years of exposure, it will be possible to derive significant constraints on both core-collapse supernova models and the supernova rate in the near universe up to redshifts z<2.

Wurm, M.; von Feilitzsch, F.; Göger-Neff, M.; Hochmuth, K. A.; Undagoitia, T. Marrodán; Oberauer, L.; Potzel, W.

2007-01-01

140

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

141

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

142

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

SciTech Connect

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

Dickens, J.K.

1991-01-01

143

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

SciTech Connect

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

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

2009-05-15

144

Standardization method of ²²Na using two NaI(Tl) scintillation detectors.  

PubMed

A new standardization method for a sealed (22)Na point source was developed utilizing two NaI(Tl) scintillation detectors. In the proposed method, the count rates of annihilation radiation, gamma rays, their coincidence sum, and the coincidences between the two detectors are used. The equations from which the source activity can be deduced are derived in this work. A series of EGS-5 Monte Carlo calculations were conducted to test the validity of the expressions. The calculated activity agreed within approximately 1 percent with the literature data used as input in the simulations. PMID:24411317

Sato, Y; Yamada, T; Hasegawa, T

2014-05-01

145

Design and test of a large-area scintillation detector for fast neutrons  

NASA Astrophysics Data System (ADS)

A plastic scintillator array of 3.4 m2 total area for the detection of neutrons in medium-energy nucleon-nucleon reactions was constructed and built. Calibration procedures for the detector were developed which allow the monitoring of gain shifts by means of muons from the cosmic radiation. Experiments were performed in order to calibrate the efficiency simulations and study the performance of the detector using the d+t??+n reaction at 14.7 MeV neutron energy and proton-induced deuteron breakup at 300 MeV.

Karsch, L.; Böhm, A.; Brinkmann, K.-Th.; Demirörs, L.; Pfuff, M.

2001-03-01

146

Monte Carlo calculated response of the dual thin scintillation detector in the sum coincidence mode  

SciTech Connect

The Dual Thin Scintillator (DTS) is a unique neutron detector that is being developed for improved fluence and spectrum measurement. Current attention has been directed towards understanding some details of the detector response in the sum coincidence mode of operation where a peaked pulse height response is exhibited throughout the energy region of interest. As a result of the peaked distribution, the detector efficiency is a weak function of the pulse height bias, allowing the number of recorded events above the bias to be determined with greater certainty. A Monte Carlo code has been used to calculate the sum coincidence pulse height response at several energies within the 1 to 15 MeV region. The detector efficiency as a function of neutron energy has also been calculated. The results of the Monte Carlo calculations, which include the effect of multiple scattering on the shape of the response function and efficiency curve are presented.

Duvall, K.C.; Johnson, R.G.

1988-01-01

147

Characterisation and calibration of a scintillating fibre detector with >4000 multi-anode photomultiplier channels  

NASA Astrophysics Data System (ADS)

In the KAOS spectrometer at the Mainz Microtron a high-resolution coordinate detector for high-energy particles is operated. It consists of scintillating fibres with diameters of <1 mm and is read out by >4000 multi-anode photomultiplier channels. It is one of the most modern focal-plane detectors for magnetic spectrometers world-wide. To correct variations in the detection efficiency, caused by the different gains and the different optical transmittances, a fully automated off-line calibration procedure has been developed. The process includes the positioning of a radioisotope source alongside the detector plane and the automated acquisition and analysis of the detector signals. It was possible to characterise and calibrate each individual fibre channel with a low degree of human interaction.

Esser, A.; Achenbach, P.; Ayerbe Gayoso, C.; Biroth, M.; Gülker, P.; Pochodzalla, J.

2012-12-01

148

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

NASA Astrophysics Data System (ADS)

In this work Al 2O 3 and SiO 2 coatings are tested as Xe diffusion barriers on plastic scintillator substrates. The motivation is improved beta-gamma coincidence detection systems, used to measure atmospheric radioxenon within the verification regime of the Comprehensive Nuclear-Test-Ban Treaty. One major drawback with the current setup of these systems is that the radioxenon tends to diffuse into the plastic scintillator material responsible for the beta detection, resulting in an unwanted memory effect. Here, coatings with thicknesses between 20 and 900 nm have been deposited onto plastic scintillators, and investigated using two different experimental techniques. The results show that all tested coatings reduce the Xe diffusion into the plastic. The reduction is observed to increase with coating thickness for both coating materials. The 425 nm Al 2O 3 coating is the most successful one, presenting a diffusion reduction of a factor 100, compared to uncoated plastic. In terms of memory effect reduction this coating is thus a viable solution to the problem in question.

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

2011-11-01

149

Study of neutron response and n-? discrimination by charge comparison method for small liquid scintillation detector  

NASA Astrophysics Data System (ADS)

The study of the neutron response and n-? discrimination for small 18×26×8 mm 3 liquid scintillator BC501A (Bicron) detector was carried out by digital charge comparison method. Three ranges of neutron energies were used: uniform distribution from 0.95-1.23 MeV, continuous spectra of AmBe source and monoenergetic 16.2 MeV neutrons. The obtained results are compared with those of cylindrical liquid scintillation detector (40 mm diameter, 60 mm length) at the same energies of neutrons. A dramatic fall of the neutron response function at 400 keV ee for small detector at 16.2 MeV neutron energy was measured. For 0.95-1.23 MeV neutron energy range such fall takes place at 260 keV ee. The greater slope of neutron locus at 0.95-1.23 MeV neutron energy compared to 16.2 MeV for both detectors is explained by longer tail of pulse from proton recoils within 0.1-1.23 MeV energy range.

?erný, J.; Doležal, Z.; Ivanov, M. P.; Kuzmin, E. S.; Švejda, J.; Wilhelm, I.

2004-07-01

150

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

151

A Geant Study of the Scintillating Optical Fiber (SOFCAL) Cosmic Ray Detector  

NASA Technical Reports Server (NTRS)

Recent energy measurements by balloon-borne passive emulsion chambers indicate that the flux ratios of protons to helium nuclei and of protons to all heavy nuclei decrease as the primary cosmic ray energy per nucleon increases above approx. 200 GeV/n, and suggest a "break" in the proton spectrum between 200 GeV and 5 TeV. However, these passive emulsion chambers are limited to a lower energy threshold of approx. 5 TeV/n, and cannot fully explore this energy regime. Because cosmic ray flux and composition details may be significant to acceleration models, a hybrid detector system called the Scintillating Optical Fiber Calorimeter (SOFCAL) has been designed and flown. SOFCAL incorporates both conventional passive emulsion chambers and an active calorimeter utilizing scintillating plastic fibers as detectors. These complementary types of detectors allow the balloon-borne SOFCAL experiment to measure the proton and helium spectra from approx. 400 GeV/n to approx. 20 TeV. The fundamental purpose of this study is to use the GEANT simulation package to model the hadronic and electromagnetic shower evolution of cosmic rays incident on the SOFCAL detector. This allows the interpretation of SOFCAL data in terms of charges and primary energies of cosmic rays, thus allowing the determinations of cosmic ray flux and composition as functions of primary energy.

Munroe, Ray B., Jr.

1998-01-01

152

Development of a fast radiation detector based on barium fluoride scintillation crystal  

SciTech Connect

Barium fluoride (BaF{sub 2}) is an inorganic scintillation material used for the detection of X/gamma radiation due to its relatively high density, equivalent atomic number, radiation hardness, and high luminescence. BaF{sub 2} has a potential capacity to be used in gamma ray timing experiments due to the prompt decay emission components. It is known that the light output from BaF{sub 2} has three decay components: two prompt of those at approximately 195 nm and 220 nm with a decay constant around 600-800 ps and a more intense, slow component at approximately 310 nm with a decay constant around 630 ns which hinders fast timing experiments. We report here the development of a fast radiation detector based on a BaF{sub 2} scintillation crystal employing a special optical filter device, a multiple reflection multi-path ultraviolet region short-wavelength pass light guides (MRMP-short pass filter) by using selective reflection technique, for which the intensity of the slow component is reduced to less than 1%. The methods used for this study provide a novel way to design radiation detector by utilizing scintillation crystal with several emission bands.

Han, Hetong [Northwest Institute of Nuclear Technology, NINT, Xi'an 710024, Shaanxi (China) [Northwest Institute of Nuclear Technology, NINT, Xi'an 710024, Shaanxi (China); School of Nuclear Science and Technology, Xi'an Jiaotong University, XJTU, Xi'an 710049, Shaanxi (China); Zhang, Zichuan; Weng, Xiufeng; Liu, Junhong; Zhang, Kan; Li, Gang [Northwest Institute of Nuclear Technology, NINT, Xi'an 710024, Shaanxi (China)] [Northwest Institute of Nuclear Technology, NINT, Xi'an 710024, Shaanxi (China); Guan, Xingyin [School of Nuclear Science and Technology, Xi'an Jiaotong University, XJTU, Xi'an 710049, Shaanxi (China)] [School of Nuclear Science and Technology, Xi'an Jiaotong University, XJTU, Xi'an 710049, Shaanxi (China)

2013-07-15

153

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

154

2D dosimetry in a proton beam with a scintillating GEM detector.  

PubMed

A two-dimensional position-sensitive dosimetry system based on a scintillating gas detector is being developed for pre-treatment verification of dose distributions in particle therapy. The dosimetry system consists of a chamber filled with an Ar/CF(4) scintillating gas mixture, inside which two gas electron multiplier (GEM) structures are mounted (Seravalli et al 2008b Med. Phys. Biol. 53 4651-65). Photons emitted by the excited Ar/CF(4) gas molecules during the gas multiplication in the GEM holes are detected by a mirror-lens-CCD camera system. The intensity distribution of the measured light spot is proportional to the 2D dose distribution. In this work, we report on the characterization of the scintillating GEM detector in terms of those properties that are of particular importance in relative dose measurements, e.g. response reproducibility, dose dependence, dose rate dependence, spatial and time response, field size dependence, response uniformity. The experiments were performed in a 150 MeV proton beam. We found that the detector response is very stable for measurements performed in succession (sigma = 0.6%) and its response reproducibility over 2 days is about 5%. The detector response was found to be linear with the dose in the range 0.05-19 Gy. No dose rate effects were observed between 1 and 16 Gy min(-1) at the shallow depth of a water phantom and 2 and 38 Gy min(-1) at the Bragg peak depth. No field size effects were observed in the range 120-3850 mm(2). A signal rise and fall time of 2 micros was recorded and a spatial response of

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

2009-06-21

155

2D dosimetry in a proton beam with a scintillating GEM detector  

NASA Astrophysics Data System (ADS)

A two-dimensional position-sensitive dosimetry system based on a scintillating gas detector is being developed for pre-treatment verification of dose distributions in particle therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside which two gas electron multiplier (GEM) structures are mounted (Seravalli et al 2008b Med. Phys. Biol. 53 4651-65). Photons emitted by the excited Ar/CF4 gas molecules during the gas multiplication in the GEM holes are detected by a mirror-lens-CCD camera system. The intensity distribution of the measured light spot is proportional to the 2D dose distribution. In this work, we report on the characterization of the scintillating GEM detector in terms of those properties that are of particular importance in relative dose measurements, e.g. response reproducibility, dose dependence, dose rate dependence, spatial and time response, field size dependence, response uniformity. The experiments were performed in a 150 MeV proton beam. We found that the detector response is very stable for measurements performed in succession (? = 0.6%) and its response reproducibility over 2 days is about 5%. The detector response was found to be linear with the dose in the range 0.05-19 Gy. No dose rate effects were observed between 1 and 16 Gy min-1 at the shallow depth of a water phantom and 2 and 38 Gy min-1 at the Bragg peak depth. No field size effects were observed in the range 120-3850 mm2. A signal rise and fall time of 2 µs was recorded and a spatial response of <=1 mm was measured.

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

2009-06-01

156

Advances in the growth of alkaline-earth halide single crystals for scintillator detectors  

SciTech Connect

Alkaline-earth scintillators such as strontium iodide and other alkaline-earth halides activated with divalent europium represent some of the most efficient and highest energy resolution scintillators for use as gamma-ray detectors in a wide range of applications. These applications include the areas of nuclear nonproliferation, homeland security, the detection of undeclared nuclear material, nuclear physics and materials science, medical diagnostics, space physics, high energy physics, and radiation monitoring systems for first responders, police, and fire/rescue personnel. Recent advances in the growth of large single crystals of these scintillator materials hold the promise of higher crystal yields and significantly lower detector production costs. In the present work, we describe new processing protocols that, when combined with our molten salt filtration methods, have led to advances in achieving a significant reduction of cracking effects during the growth of single crystals of SrI2:Eu2+. In particular, we have found that extended pumping on the molten crystal-growth charge under vacuum for time periods extending up to 48 hours is generally beneficial in compensating for variations in the alkaline-earth halide purity and stoichiometry of the materials as initially supplied by commercial sources. These melt-pumping and processing techniques are now being applied to the purification of CaI2:Eu2+ and some mixed-anion europium-doped alkaline-earth halides prior to single-crystal growth by means of the vertical Bridgman technique. The results of initial studies of the effects of aliovalent doping of SrI2:Eu2+ on the scintillation characteristics of this material are also described.

Boatner, Lynn A [ORNL; Ramey, Joanne Oxendine [ORNL; Kolopus, James A [ORNL; Neal, John S [ORNL; Cherepy, Nerine [Lawrence Livermore National Laboratory (LLNL); Payne, Stephen A. [Lawrence Livermore National Laboratory (LLNL); Beck, P [Lawrence Livermore National Laboratory (LLNL); Burger, Arnold [Fisk University, Nashville; Rowe, E [Fisk University, Nashville; Bhattacharya, P. [Fisk University, Nashville

2014-01-01

157

Advances in the growth of alkaline-Earth halide single crystals for scintillator detectors  

NASA Astrophysics Data System (ADS)

Alkaline-earth scintillators such as strontium iodide and other alkaline-earth halides activated with divalent europium represent some of the most efficient and highest energy resolution scintillators for use as gamma-ray detectors in a wide range of applications. These applications include the areas of nuclear nonproliferation, homeland security, the detection of undeclared nuclear material, nuclear physics and materials science, medical diagnostics, space physics, high energy physics, and radiation monitoring systems for first responders, police, and fire/rescue personnel. Recent advances in the growth of large single crystals of these scintillator materials hold the promise of higher crystal yields and significantly lower detector production costs. In the present work, we describe new processing protocols that, when combined with our molten salt filtration methods, have led to advances in achieving a significant reduction of cracking effects during the growth of single crystals of SrI2:Eu2+. In particular, we have found that extended pumping on the molten crystalgrowth charge under vacuum for time periods extending up to 48 hours is generally beneficial in compensating for variations in the alkaline-earth halide purity and stoichiometry of the materials as initially supplied by commercial sources. These melt-pumping and processing techniques are now being applied to the purification of CaI2:Eu2+ and some mixed-anion europium-doped alkaline-earth halides prior to single-crystal growth by means of the vertical Bridgman technique. The results of initial studies of the effects of aliovalent doping of SrI2:Eu2+ on the scintillation characteristics of this material are also described.

Boatner, L. A.; Ramey, J. O.; Kolopus, J. A.; Neal, J. S.; Cherepy, N. J.; Beck, P. R.; Payne, S. A.; Burger, A.; Rowe, E.; Bhattacharya, P.

2014-09-01

158

Simulation study of the neutron-gamma discrimination capability of a liquid scintillator neutron detector  

NASA Astrophysics Data System (ADS)

The capability to discriminate between neutrons and gamma rays (n/?) by means of their pulse shapes is important for many users of liquid scintillator (LS) neutron detectors. To simulate the n/? discrimination capability of a neutron detector, we have developed a method to simulate the pulse signal generated by an incident n or ? in the LS. Light pulses caused by ionization and excitation from incident n or ? radiation are simulated by the Geant4 simulation package based on the geometry and materials of a prototype LS detector. The response to the incident light of the photomultiplier tube (PMT) and data acquisition (DAQ) circuit was obtained from a single photoelectron experiment. The final output signal from a detector was produced by convolving its light pulse with the response function of the PMT and DAQ. Two methods, the charge comparison method (CCM) and the pulse gradient method (PGM), were applied to discriminate the simulated signals. The simulation was validated by comparing its result to an experimental result from the prototype LS detector. Our method can be applied in the design of an LS detector, which has subsequently been optimized n/? discrimination. The method can also be helpful to analyze experimental data and evaluate the performance of n/? discrimination techniques.

Xing, Haoyang; Yu, Xunzhen; Zhu, Jingjun; Wang, Li; Ma, Jinglu; Liu, Shukui; Li, Linwei; Chen, Liejian; Tang, Changjian; Yue, Qian

2014-12-01

159

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

NASA Astrophysics Data System (ADS)

A new type of neutron dose monitor was developed by using a 12.7 cm diameter×12.7 cm long boron-loaded organic liquid scintillation detector BC523A. This detector aims to have a response in the wide energy range of thermal energy to 100 MeV by using the H and C reactions to the fast neutrons of organic liquid and the 10B(n, ?) reaction to thermalized neutrons in the liquid. The response functions of this detector were determined by the Monte Carlo simulation in the energy region from thermal energy to 100 MeV. Using these response functions, the spectrum-weighted dose function, G-function, to get the neutron dose from the light output spectrum of the detector was also determined by the unfolding technique. The calculated G-function was applied to determine the neutron dose in real neutron fields having energies ranging from thermal energy to several tens of MeV, where the light output spectra were measured with the BC523A detector. The thus-obtained ambient doses and effective doses show rather good agreement with the fluence-to-dose conversion factor given by ICRP 74. This detector will be useful as a wide-energy range neutron monitor.

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

2002-10-01

160

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

161

Alignment of the Near Detector scintillator modules using cosmic ray muons  

SciTech Connect

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

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

2008-05-01

162

Predicting the sensitivity of the beryllium/scintillator layer neutron detector using Monte Carlo and experimental response functionsa)  

NASA Astrophysics Data System (ADS)

A methodology for obtaining empirical curves relating absolute measured scintillation light output to beta energy deposited is presented. Output signals were measured from thin plastic scintillator using NIST traceable beta and gamma sources and MCNP5 was used to model the energy deposition from each source. Combining the experimental and calculated results gives the desired empirical relationships. To validate, the sensitivity of a beryllium/scintillator-layer neutron activation detector was predicted and then exposed to a known neutron fluence from a Deuterium-Deuterium fusion plasma (DD). The predicted and the measured sensitivity were in statistical agreement.

Styron, J. D.; Cooper, G. W.; Ruiz, C. L.; Hahn, K. D.; Chandler, G. A.; Nelson, A. J.; Torres, J. A.; McWatters, B. R.; Carpenter, Ken; Bonura, M. A.

2014-11-01

163

Development of Scintillator Detectors for Fast-Ignition Experiments and Down-Scattered Neutron Measurements on OMEGA  

NASA Astrophysics Data System (ADS)

A small signal must be recorded after very large DT or hard x-ray signals in a neutron time-of-flight detector to measure down-scattered neutrons in cryogenic DT implosions or to measure neutron yield in the presence of hard x-ray background from an ultrahigh-intensity laser. Several detectors with plastic and liquid scintillators were developed and tested at the Omega/Omega EP Laser Facility in cryogenic DT implosions and integrated fast-ignition experiments. A gated photomultiplier tube was used to eliminate large DT or hard x-ray signals. The liquid scintillator consists of 0.4% PPO, 0.04% MSB dissolved in xylene and saturated with oxygen. The afterglow (long decay constant) with this scintillator is ˜100x less than conventional scintillators. This is an essential property to mitigate the residual scintillator signal in down-scattered neutron measurements and fast-ignition experiments. Detector designs and responses with the different scintillators will be presented. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement Nos. DE-FC52-08NA28302, DE-FC02-04ER54789, and DE-FG02-05ER54839.

Glebov, V. Yu.; Stoeckl, C.; Theobald, W.; Sangster, T. C.; Marshall, K. L.; Shoup, M. J., III; Buczek, T.; Pruyne, A.; Fox, M.; Duffy, T.; Moran, M. J.; Lauck, R.

2009-11-01

164

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

PubMed

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

Zimbal, A

2007-01-01

165

Improving Photoelectron Counting and Particle Identification in Scintillation Detectors with Bayesian Techniques  

E-print Network

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

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

2014-08-08

166

Application of artificial neural networks for unfolding neutron spectra by using a scintillation detector  

NASA Astrophysics Data System (ADS)

The unfolding of neutron spectra from the pulse height distribution measured by a BC501A scintillation detector is accomplished by the application of artificial neural networks (ANN). A simple linear neural network without biases and hidden layers is adopted. A set of monoenergetic detector response functions in the energy range from 0.25 MeV to 16 MeV with an energy interval of 0.25 MeV are generated by the Monte Carlo code O5S in the training phase of the unfolding process. The capability of ANN was demonstrated successfully using the Monte Carlo data itself and experimental data obtained from the Am-Be neutron source and D-T neutron source.

Yan, Jie; Liu, Rong; Li, Cheng; Jiang, Li; Wang, Mei

2011-03-01

167

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

168

Low energy neutrino astrophysics with the large liquid-scintillator detector LENA  

NASA Astrophysics Data System (ADS)

The large-volume liquid-scintillator detector LENA (Low Energy Neutrino Astronomy) will cover a broad field of physics. Apart from the detection of terrestrial and artificial neutrinos, and the search for proton decay, important contributions can be made to the astrophysics of stars by high-precision spectroscopy of low-energetic solar neutrinos and by the observation of neutrinos emitted by a galactic supernova. Moreover, the detection of the diffuse supernova neutrino background in LENA will offer the opportunity of studying both supernova core-collapse models and the supernova rate on cosmological timescales (z<2). Significant constraints can be derived after ten years of exposure, resulting in ~100 ?e events in an almost background-free energy window from ~10 to 25 MeV. The search for such rare low-energetic events takes advantage of the high energy resolution and excellent background rejection possible in the LENA detector.

Wurm, M.; von Feilitzsch, F.; Göger-Neff, M.; Undagoitia, T. Marrodán; Oberauer, L.; Potzel, W.; Winter, J.

2007-11-01

169

Unfolding the fast neutron spectra of a BC501A liquid scintillation detector using GRAVEL method  

NASA Astrophysics Data System (ADS)

Accurate knowledge of the neutron energy spectra is useful in basic research and applications. The overall procedure of measuring and unfolding the fast neutron energy spectra with BC501A liquid scintillation detector is described. The recoil proton spectrum of 241Am-Be neutrons was obtained experimentally. With the NRESP7 code, the response matrix of detector was simulated. Combining the recoil proton spectrum and response matrix, the unfolding of neutron spectra was performed by GRAVEL iterative algorithm. A MatLab program based on the GRAVEL method was developed. The continuous neutron spectrum of 241Am-Be source and monoenergetic neutron spectrum of D-T source have been unfolded successfully and are in good agreement with their standard reference spectra. The unfolded 241Am-Be spectrum are more accurate than the spectra unfolded by artificial neural networks in recent years.

Chen, YongHao; Chen, XiMeng; Lei, JiaRong; An, Li; Zhang, XiaoDong; Shao, JianXiong; Zheng, Pu; Wang, XinHua

2014-10-01

170

Measuring Muon-Induced Neutrons with Large Liquid Scintillation Detector at Soudan Mine  

E-print Network

We report a first direct detection of muon-induced high energy neutrons with a 12-liter neutron detector fabricated with EJ-301 liquid scintillator operating at Soudan Mine for about two years. The detector response to energy from a few MeV up to $\\sim$ 20 MeV has been calibrated using radioactive sources and cosmic-ray muons. Subsequently, we have developed an approach to calculate the scintillation efficiency for nuclear recoils up to a few hundred MeV. Data from an exposure of 655 days were analyzed for high energy neutrons using pulse shape discrimination which allowed us to detect muon-induced fast neutrons with energy up to a few hundred MeV for the first time. The muon-induced fast neutron flux for neutron energy greater than 10 MeV is measured to be ($4.73 \\pm 1.1 (sta.) \\pm 0.4 (sys.) ) \\times10^{-9}$ cm$^{-2}s^{-1}$, in a reasonable agreement with the model prediction. The muon flux is found to be ($1.65\\pm 0.02 (sta.) \\pm 0.1 (sys.) ) \\times10^{-7}$ cm$^{-2}s^{-1}$, consistent with other measurements. As a result, the muon-induced high energy gamma-ray flux is simulated to be 7.08 $\\times$10$^{-7}$cm$^{-2}s^{-1}$ for the depth of Soudan.

C. Zhang; D. -M. Mei

2014-07-11

171

Measuring Muon-Induced Neutrons with Large Liquid Scintillation Detector at Soudan Mine  

E-print Network

We report a first direct detection of muon-induced high energy neutrons with a 12-liter neutron detector fabricated with EJ-301 liquid scintillator operating at Soudan Mine for about two years. The detector response to energy from a few MeV up to $\\sim$ 20 MeV has been calibrated using radioactive sources and cosmic-ray muons. Subsequently, we have developed an approach to calculate the scintillation efficiency for nuclear recoils up to a few hundred MeV. Data from an exposure of 655 days were analyzed for high energy neutrons using pulse shape discrimination which allowed us to detect muon-induced fast neutrons with energy up to a few hundred MeV for the first time. The muon-induced fast neutron flux for neutron energy greater than 10 MeV is measured to be ($4.73 \\pm 1.1 (sta.) \\pm 0.4 (sys.) ) \\times10^{-9}$ cm$^{-2}s^{-1}$, in a reasonable agreement with the model prediction. The muon flux is found to be ($1.65\\pm 0.02 (sta.) \\pm 0.1 (sys.) ) \\times10^{-7}$ cm$^{-2}s^{-1}$, consistent with other measuremen...

Zhang, C

2014-01-01

172

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

173

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

PubMed

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. PMID:23756497

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

2013-07-01

174

Application of scintillating fiber gamma-ray detectors for medical imaging  

NASA Astrophysics Data System (ADS)

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

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

1993-02-01

175

Performance of lanthanide-halide scintillation detectors in prompt gamma analysis of bulk samples  

NASA Astrophysics Data System (ADS)

Performance tests of cylindrical 3" x 3" (LaBr3:Ce and LaCl3:Ce) and 5" x 5" (BGO) detectors were carried out to detect low energy prompt gamma-rays from boron contaminated water samples using a newly designed portable neutron generator-based Prompt Gamma Neutron Activation Analysis (PGNAA) setup. Prompt gamma-rays were measured from water samples contaminated with 0.031 to 0.5 wt% boron. The experimental yield of boron prompt gamma-rays measured with LaBr3:Ce, LaCl3:Ce and BGO detectors based PGNAA setup were compared. An excellent agreement has been observed between the experimental and calculated yield of boron prompt gamma ray from water samples. Minimum detection concentrations (MDC)s of boron in water samples for LaBr3:Ce, LaCl3:Ce and BGO detectors were determined to be: 30 ± 9.3, 45 ± 16.4, 28 ± 8 (ppm) respecteviley which agree with each other within statistical uncertainty.

Al-Anezi, Mohammad Saleh

176

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

177

Position Sensitivity of the SuN (Summing NaI(Tl)) Scintillation Detector  

NASA Astrophysics Data System (ADS)

The astrophysical p-process is responsible for the synthesis of many proton rich nuclei. It involves photo disintegration reactions such as (gamma,alpha), (gamma,n) and (gamma,p) reactions. To try to understand the reaction flow and reproduce the p-nuclei abundances, we will try to study the inverse reactions, namely (p,gamma) and (alpha,gamma). A beam of a heavy nuclei will be impinging on a H or He rich target, and by using the 4? ?-summing method, the cross section of (p,gamma) and (alpha,gamma) reactions will be measured. To do so, the Nuclear Astrophysics group at NSCL (National Superconducting Cyclotron Laboratory) is developing a scintillation detector. The SuN (Summing NaI) detector consists of eight semicircular segments, each with three PMTs (photomultiplier tubes) attached. This 4? gamma-summing detector will allow us to measure the cross sections of important p-process reactions. The goal of my research was to find the correlation between the position of an event in the crystal and the signal recorded by each PMT. By correcting for this position dependence of the signals the energy resolution of the detector was improved. First results from this investigation will be presented.

Beskin, Ilya; Spyrou, Artemis; Quinn, Stephen; Peace, Jessica; Simon, Anna

2011-10-01

178

[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

179

COS FUV01 Detector Initial Setup Values Date: August 8, 2002  

E-print Network

which occurs long after the final build of the FSW. Consequently, the plan for managing these detector settings has always been to set these initial values in the FUV FSW by a nominal sequence of DCE commands, which are sent during defined transitions of the FUV Detector subsystem. The CS-DCE FSW has a specific

Colorado at Boulder, University of

180

KLauS: an ASIC for silicon photomultiplier readout and its application in a setup for production testing of scintillating tiles  

NASA Astrophysics Data System (ADS)

KLauS is an ASIC produced in the AMS 0.35 ?m SiGe process to read out the charge signals from silicon photomultipliers. Developed as an analog front-end for future calorimeters with high granularity as pursued by the AHCAL concept in the CALICE collaboration, the ASIC is designed to measure the charge signal of the sensors in a large dynamic range and with low electronic noise contributions. In order to tune the operation voltage of each sensor individually, an 8-bit DAC to tune the voltage at the input terminal within a range of 2V is implemented. Using an integrated fast comparator with low jitter, the time information can be measured with sub-nanosecond resolution. The low power consumption of the ASIC can be further decreased using power gating techniques. Future versions of KLauS are under development and will incorporate an ADC with a resolution of up to 12-bits and blocks for digital data transmission. The chip is used in a setup for mass testing and characterization of scintillator tiles for the AHCAL test beam program.

Briggl, K.; Dorn, M.; Hagdorn, R.; Harion, T.; Schultz-Coulon, H. C.; Shen, W.

2014-02-01

181

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

Microsoft Academic Search

Main types of photoreceivers used in X-ray digital radiography systems are luminescent screens that transfer the optical image onto charge collection instruments, which require cooling, and semiconductor silicon detectors, which limit the contrast sensitivity. We have developed and produced X-ray radiation detectors of ``scintillator-photoreceiving device'' (S-PRD) type, which are integrally located on the inverse side of the photodiode (PD). The

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

2003-01-01

182

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

Microsoft Academic Search

Main types of photoreceivers used in X-ray digital radiography systems are luminescent screens that transfer the optical image onto charge collection instruments, which require cooling, and semiconductor silicon detectors, which limit the contrast sensitivity. We have developed and produced X-ray radiation detectors of “scintillator-photoreceiving device” (S-PRD) type, which are integrally located on the inverse side of the photodiode (PD). The

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

2003-01-01

183

Tomographic analysis of neutron and gamma pulse shape distributions from liquid scintillation detectors at Joint European Torus.  

PubMed

The Joint European Torus (JET, Culham, UK) is the largest tokamak in the world devoted to nuclear fusion experiments of magnetic confined Deuterium (D)/Deuterium-Tritium (DT) plasmas. Neutrons produced in these plasmas are measured using various types of neutron detectors and spectrometers. Two of these instruments on JET make use of organic liquid scintillator detectors. The neutron emission profile monitor implements 19 liquid scintillation counters to detect the 2.45 MeV neutron emission from D plasmas. A new compact neutron spectrometer is operational at JET since 2010 to measure the neutron energy spectra from both D and DT plasmas. Liquid scintillation detectors are sensitive to both neutron and gamma radiation but give light responses of different decay time such that pulse shape discrimination techniques can be applied to identify the neutron contribution of interest from the data. The most common technique consists of integrating the radiation pulse shapes within different ranges of their rising and/or trailing edges. In this article, a step forward in this type of analysis is presented. The method applies a tomographic analysis of the 3-dimensional neutron and gamma pulse shape and pulse height distribution data obtained from liquid scintillation detectors such that n/? discrimination can be improved to lower energies and additional information can be gained on neutron contributions to the gamma events and vice versa. PMID:24593359

Giacomelli, L; Conroy, S; Gorini, G; Horton, L; Murari, A; Popovichev, S; Syme, D B

2014-02-01

184

Tomographic analysis of neutron and gamma pulse shape distributions from liquid scintillation detectors at Joint European Torus  

NASA Astrophysics Data System (ADS)

The Joint European Torus (JET, Culham, UK) is the largest tokamak in the world devoted to nuclear fusion experiments of magnetic confined Deuterium (D)/Deuterium-Tritium (DT) plasmas. Neutrons produced in these plasmas are measured using various types of neutron detectors and spectrometers. Two of these instruments on JET make use of organic liquid scintillator detectors. The neutron emission profile monitor implements 19 liquid scintillation counters to detect the 2.45 MeV neutron emission from D plasmas. A new compact neutron spectrometer is operational at JET since 2010 to measure the neutron energy spectra from both D and DT plasmas. Liquid scintillation detectors are sensitive to both neutron and gamma radiation but give light responses of different decay time such that pulse shape discrimination techniques can be applied to identify the neutron contribution of interest from the data. The most common technique consists of integrating the radiation pulse shapes within different ranges of their rising and/or trailing edges. In this article, a step forward in this type of analysis is presented. The method applies a tomographic analysis of the 3-dimensional neutron and gamma pulse shape and pulse height distribution data obtained from liquid scintillation detectors such that n/? discrimination can be improved to lower energies and additional information can be gained on neutron contributions to the gamma events and vice versa.

Giacomelli, L.; Conroy, S.; Gorini, G.; Horton, L.; Murari, A.; Popovichev, S.; Syme, D. B.

2014-02-01

185

A total absorption scintillation detector for electrons, photons and other particles in the GeV region  

Microsoft Academic Search

A report is presenteo on measurements taken with a total absorption ; scintillation detector. The energy response and the resolution of the counter ; was investigated with electrons between 1 and 10 Bev\\/c. It appears that the ; counter provides a practical linear device for the measurement of electron or ; gamma -ray energies in this region. The counter is

G. Backenstoss; B. D. Hyams; G. Knop; U. Stierlin

1963-01-01

186

A scintillating-fiber 14-MeV neutron detector on TFTR during DT operation  

SciTech Connect

A compact 14-MeV neutron detector using an array of scintillating fibers has been tested on the TFTR tokamak under conditions of a high gamma background. This detector uses a fiber-matrix geometry, a magnetic field-insensitive phototube with an active HV base and pulse-height discrimination to reject low-level pulses from 2.5 MeV neutron and intense gammas. Laboratory calibrations have been performed at EG&G Las Vegas using a pulsed DT neutron generator and a 30 kCi {sup 60}Co source as background, at PPPL using DT neutron sources, and at LANL using an energetic deuterium beam and target at a tandem Van de Graaff accelerator. During the first high power DT shots on TFTR in December 1993, the detector was 15.5 meters from the torus in a large collimator. For a rate of 1 {times} 10{sup 18} n/sec from the tokamak, it operated in an equivalent background of 1 {times} 10{sup 10} gammas/cm{sup 2}/sec ({approximately}4 mA current drain) at a DT count rate of 200 kHz.

Wurden, G.A.; Chrien, R.E.; Barnes, C.W.; Sailor, W.C. [Los Alamos National Lab., NM (United States); Roquemore, A.L. [Princeton Plasma Physics Lab., NJ (United States); Lavelle, M.J.; O`Gara, P.M.; Jordan, R.J. [EG& G Energy Measurements, Las Vegas, NV (United States)

1994-07-01

187

LHCb: The Front-End electronics for the LHCb scintillating fibres detector  

E-print Network

The LHCb detector will be upgraded during the next LHC shutdown in 2018/19. The tracker system will have a major overhaul. Its components will be replaced with new technologies in order to cope with the increased hit occupancy and radiation environment. A detector made of scintillating fibres read out by silicon photomultipliers (SiPM) is studied for this upgrade. Even if this technology has proven to achieve high efficiency and spatial resolution, its integration within a LHC experiment bears new challenges. This detector will consist of 12 planes of 5 to 6 layers of 250 $\\mu$m fibres with an area of 5×6 m$^2$. Its lead to a total of 500k SiPM channels which need to will be read out at 40MHz. This talk gives an overview of the R&D status of the readout board and the PACIFIC chip. The readout board is connected to the SiPM on one side and to the experiment data-acquisition, experimental control system and services on the other side . The PACIFIC chip is a 128 channel ASIC which can be connected to one 12...

Chanal, H; Pillet, N

2014-01-01

188

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

189

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

SciTech Connect

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

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

2010-09-01

190

Toward a real-time in vivo dosimetry system using plastic scintillation detectors  

PubMed Central

Purpose In this work, we present and validate a plastic scintillation detector (PSD) system designed for real-time multi-probe in vivo measurements. Methods and Materials The PSDs were built with a dose-sensitive volume of 0.4 mm3. PSDs were assembled into modular detector patches, each containing 5 closely packed PSDs. Continuous dose readings were performed every 150 ms, with a gap between consecutive readings of less than 0.3 ms. We first studied the effect of electron multiplication. We then assessed system performance in acrylic and anthropomorphic pelvic phantoms. Results The PSDs are compatible with clinical rectal balloons and are easily inserted into the anthropomorphic phantom. With an electron multiplication average gain factor of 40, a twofold increase in the signal-to-noise ratio was observed, making near real-time dosimetry feasible. Under calibration conditions, the PSDs agreed with ion chamber measurements to 0.08%. Precision, evaluated as a function of the total dose delivered, ranged from 2.3% at 2 cGy to 0.4% at 200 cGy. Conclusion Real-time PSD measurements are highly accurate and precise. These PSDs can be mounted onto rectal balloons, transforming these clinical devices into in vivo dose detectors without modifying current clinical practice. Real-time monitoring of the dose delivered near the rectum during prostate radiation therapy should help radiation oncologists protect this sensitive normal structure. PMID:20231074

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

2010-01-01

191

Measurement of loss of DT fusion products using scintillator detectors in TFTR  

SciTech Connect

A poloidal array of MeV ion loss probes previously used to measure DD fusion product loss has been upgraded to measure the loss of alpha particles from DT plasmas in TFTR. The following improvements to the system have been made in preparation for the use of tritium in TFTR: (1) relocation of detectors to a neutronshielded enclosure in the basement to reduce neutron-induced background signals; (2) replacement of ZnS:Cu (P31) scintillators in the probes with the Y{sub 3}Al{sub 5}0{sub 12}:Ce(P46) variety to minimize damage and assure linearity at the fluxes anticipated from DT plasmas; and (3) shielding of the fiber optic bundles which carry the fight from the probes to the detectors to reduce neutron- and gamma-induced light within them. In addition to the above preparations, the probes have been absolutely calibrated for alpha particles by using the Van de Graaf accelerator at Los Alamos National Laboratory. Alpha particle losses from DT plasmas have been observed, and losses at the detector 901 below the midplane are consistent with first orbit loss.

Darrow, D.S.; Herrmann, H.W.; Johnson, D.W.; Marsala, R.J.; Palladino, R.W.; Zweben, S.J. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Tuszewski, M. [Los Alamos National Lab., NM (United States)

1995-03-01

192

A SiPM-based ZnS:$^6$LiF scintillation neutron detector  

E-print Network

In the work presented here we built and evaluated a single-channel neutron detection unit consisting of a ZnS:$^6$LiF scintillator with embedded WLS fibers readout by a SiPM. The unit has a sensitive volume of 2.4 x 2.8 x 50 mm$^3$; 12 WLS fibers of diameter 0.25 mm are uniformly distributed over this volume and are coupled to a 1 x 1 mm$^2$ active area SiPM. We report the following performance parameters: neutron detection efficiency $\\sim 65\\,$% at $1.2\\,\\AA$, background count rate $detection unit as an elementary building block for realization of one-dimensional multichannel detectors for applications in the neutron scattering experimental technique. The dimensions of the unit and the number of embedded fibers can be varied to meet the specific application requirements. The upp...

Stoykov, A; Greuter, U; Hildebrandt, M; Schlumpf, N

2014-01-01

193

Borexino: A real time liquid scintillator detector for low energy solar neutrino study  

E-print Network

Borexino is a large unsegmented calorimeter featuring 300 tons of liquid scintillator, contained in a 8.5 meter nylon vessel, viewed by 2200 PMTs. The main goal of Borexino is the study, in real time, of low energy solar neutrinos, and in particular, the monoenergetic neutrinos coming from $^7Be$, which is one of the missing links on the solar neutrino problem. The achievement of high radiopurity level, in the order of $10^{-16} g/g$ of U/Th equivalent, necessary to the detection of the low energy component of the solar neutrino flux, was proved in the Borexino prototype: the Counting Test Facility. The detector is located underground in the Laboratori Nazionali del Gran Sasso in the center of Italy at 3500 meter water equivalent depth. In this paper the science and technology of Borexino are reviewed and its main capabilities are presented.

Lino Miramonti

2002-06-25

194

A universal setup for active control of a single-photon detector.  

PubMed

The influence of bright light on a single-photon detector has been described in a number of recent publications. The impact on quantum key distribution (QKD) is important, and several hacking experiments have been tailored to fully control single-photon detectors. Special attention has been given to avoid introducing further errors into a QKD system. We describe the design and technical details of an apparatus which allows to attack a quantum-cryptographic connection. This device is capable of controlling free-space and fiber-based systems and of minimizing unwanted clicks in the system. With different control diagrams, we are able to achieve a different level of control. The control was initially targeted to the systems using BB84 protocol, with polarization encoding and basis switching using beamsplitters, but could be extended to other types of systems. We further outline how to characterize the quality of active control of single-photon detectors. PMID:24517746

Liu, Qin; Lamas-Linares, Antía; Kurtsiefer, Christian; Skaar, Johannes; Makarov, Vadim; Gerhardt, Ilja

2014-01-01

195

A universal setup for active control of a single-photon detector  

E-print Network

The influence of bright light on a single-photon detector has been described in a number of recent publications. The impact on quantum key distribution (QKD) is important, and several hacking experiments have been tailored to fully control single-photon detectors. Special attention has been given to avoid introducing further errors into a QKD system. We describe the design and technical details of an apparatus which allows to attack a quantum-cryptographic connection. This device is capable of controlling free-space and fiber-based systems and of minimizing unwanted clicks in the system. With different control diagrams, we are able to achieve a different level of control. The control was initially targeted to the systems using BB84 protocol, with polarization encoding and basis switching using beamsplitters, but could be extended to other types of systems. We further outline how to characterize the quality of active control of single-photon detectors.

Qin Liu; Antía Lamas-Linares; Christian Kurtsiefer; Johannes Skaar; Vadim Makarov; Ilja Gerhardt

2013-07-23

196

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

197

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

198

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. PMID:23718599

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

2013-01-01

199

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

E-print Network

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 $\\pm$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.

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

2014-01-21

200

Low Energy Neutrino Astronomy in the future large-volume liquid-scintillator detector LENA  

NASA Astrophysics Data System (ADS)

The recent successes in neutrino physics prove that liquid-scintillator detectors allow to combine high energy resolution, efficient means of background reduction, and a large detection volume. In the planned LENA (Low Energy Neutrino Astronomy) experiment, a target mass of 50 kt will enable the investigation of a variety of terrestrial and astrophysical neutrino sources. The high-statistics spectroscopy of geoneutrinos, solar neutrinos and supernova neutrinos will provide new insights in the heat production processes of Earth and Sun, and the workings of a gravitational collapse. The same measurements will as well investigate neutrino properties as oscillation parameters and mass hierarchy. A first spectroscopic measurement of the low flux of diffuse supernova neutrino background is within the sensitivity of the LENA detector. Finally, a life-time limit of several 1034 years can be set to the proton decay into proton and anti-neutrino, testing the predictions of SUSY theory. The present contribution includes a review of the scientific studies that were performed in the last years as well as a report on currently on-going R&D activities.

Wurm, Michael; Feilitzsch, F. V.; Göger-Neff, M.; Lewke, T.; Marrodan Undagoitia, T.; Oberauer, L.; Potzel, W.; Todor, S.; Winter, J.

2008-11-01

201

The Digital discrimination of neutron and {\\gamma} ray using organic scintillation detector based on wavelet transform modulus maximum  

E-print Network

A novel algorithm for the discrimination of neutron and {\\gamma}-ray 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 performances of most pulse shape discrimination methods in scintillation detection systems using time-domain features of the pulses are affected intensively by noise. However, the WTMM method using frequency-domain features exhibits a strong insensitivity to noise and can be used to discriminate neutron and {\\gamma}-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 frequency gradient analysis (FGA) method. It is shown that the characterization of...

yun, Yang; jun, Yang; xiaoliang, Luo

2013-01-01

202

Simulation of the precision limits of plastic scintillation detectors using optimal component selection  

PubMed Central

Purpose: The purpose of this work was threefold: First, to determine which type of charge-coupled device (CCD) would provide the best dosimetric precision for plastic scintillation detectors (PSDs); second, to design a high-photon-efficiency PSD system by optimizing its signal-to-noise ratio (SNR) using off-the-shelf technology; and third, to establish the spatial, temporal, and dose precision limits of such a PSD system. The authors have attempted to design a dosimetric tool suitable for radiotherapy treatment modalities employing small fields or fast temporal modulation of the radiation fields, and to explore the current precision limits of PSD systems. Methods: The authors used an SNR simulation model to design and calculate the dosimetric precision of a PSD employing a fiber taper to couple the optical fiber to the photodetector. The authors also used the SNR simulation model to evaluate the impact of the photodetector performance characteristics on the SNR and to establish the spatial, temporal, and dose precision limits. Results: The authors found that a high-photon-efficiency PSD can provide a precision of 1% in 45 ?s of integration time for a dose rate of 400 cGy?min when a single image is taken, detect a dose of 1 cGy with a detector volume of 0.0007 mm3, and image over 15?000 detectors with a precision of 1% on a 30.7×30.7 mm2 CCD imaging area. Conclusions: These characteristics establish that PSDs theoretically constitute a suitable dosimetric tool for radiotherapy treatment modalities employing small fields or fast temporal modulation of the radiation fields. PMID:20229849

Lacroix, Frederic; Beaulieu, Luc; Archambault, Louis; Beddar, A. Sam

2010-01-01

203

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. PMID:18293571

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

2010-01-01

204

Determination of the energy dependence of the BC-408 plastic scintillation detector in medium energy x-ray beams.  

PubMed

The energy dependence of the response of BC-408 plastic scintillator (PS), an approximately water-equivalent material, has been investigated by employing standardized x-ray beams. IEC RQA and ISO N series x-ray beam qualities, in the range of 40-100?kVp, were calibrated using a PTW-type ionization chamber. The energy response of a thick BC-408 PS detector was measured using the multichannel pulse height analysis method.The response of BC-408 PS increased gradually with increasing energy in the energy range of 40-80?kVp and then showed a flat behavior at about 80 to 120?kVp. This might be due to the self-attenuation of scintillation light by the scintillator itself and may also be partly due to the ionization quenching, leading to a reduction in the intensity of the light output from the scintillator. The results indicated that the sensitivity drop in BC-408 PS material at lower photon energies may be overcome by adding some high-Z elements to its polyvinyltoluene (PVT) base. The material modification may compensate for the drop in the response at lower photon energies. Thus plastic scintillation dosimetry is potentially suitable for applications in diagnostic radiology. PMID:25327627

Yücel, H; Cubukçu, S; Uyar, E; Engin, Y

2014-11-21

205

Determination of the energy dependence of the BC-408 plastic scintillation detector in medium energy x-ray beams  

NASA Astrophysics Data System (ADS)

The energy dependence of the response of BC-408 plastic scintillator (PS), an approximately water-equivalent material, has been investigated by employing standardized x-ray beams. IEC RQA and ISO N series x-ray beam qualities, in the range of 40–100?kVp, were calibrated using a PTW-type ionization chamber. The energy response of a thick BC-408 PS detector was measured using the multichannel pulse height analysis method. The response of BC-408 PS increased gradually with increasing energy in the energy range of 40–80?kVp and then showed a flat behavior at about 80 to 120?kVp. This might be due to the self-attenuation of scintillation light by the scintillator itself and may also be partly due to the ionization quenching, leading to a reduction in the intensity of the light output from the scintillator. The results indicated that the sensitivity drop in BC-408 PS material at lower photon energies may be overcome by adding some high-Z elements to its polyvinyltoluene (PVT) base. The material modification may compensate for the drop in the response at lower photon energies. Thus plastic scintillation dosimetry is potentially suitable for applications in diagnostic radiology.

Yücel, H.; Çubukçu, ?.; Uyar, E.; Engin, Y.

2014-11-01

206

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

207

Neutron Energy Spectra in the Vicinity of a Nuclear Reactor Measured with a Liquid Scintillation Detector with Bismuth Shield  

NASA Astrophysics Data System (ADS)

A liquid scintillation spectrometer whose detector was composed of a NE213 liquid scintillator covered with a bismuth shield was constructed to estimate energy spectra of low intensity and relatively low energy neutrons around a nuclear reactor. A response matrix used for unfolding the pulse-height distributions was obtained from the matrices representing modulations of neutron energy spectra by the bismuth shield and response functions of the liquid scintillation detector. Measurements of reactor neutrons were carried out with the aid of the pulse-shape discrimination method in the vicinity of the Kinki University Reactor, UTR-KINKI. It became clear from the experiments that the pulse-height distributions by fission neutrons could be successfully obtained by the scintillation spectrometer constructed here in spite of the measurements in the low n/?ratio fields around nuclear facility and neutron energy spectra could be determined by the unfolding technique with the response matrix in the energy range from about 1 MeV to tens of MeV.

Urabe, Itsumasa; Sagawa, Hiroyuki; Ogawa, Yoshihiro; Kobayashi, Katsuhei

2003-06-01

208

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

NASA Astrophysics Data System (ADS)

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

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

2003-06-01

209

Comparison of Cadmium Zinc Telluride semiconductor and Yttrium Aluminum Perovskite scintillator as photon detectors for epithermal neutron spectroscopy  

NASA Astrophysics Data System (ADS)

The range of applications of epithermal neutron scattering experiments has been recently extended by the development of the Resonance Detector. In a Resonance Detector, resonant neutron absorption in an analyzer foil results in prompt emission of X- and ?-rays which are detected by a photon counter. Several combinations of analyzer foils and photon detectors have been studied and tested over the years and best results have been obtained with the combination of a natural uranium and (i) Cadmium-Zinc-Telluride (CZT) semiconductor, (ii) Yttrium-Aluminum-Perovskite (YAP) scintillators. Here we compare the performance of the CZT semiconductor and YAP scintillator as Resonance Detector units. Two Resonance Detector prototypes made of natural uranium foil viewed by CZT and YAP were tested on the VESUVIO spectrometer at the ISIS spallation neutron source. The results show that both YAP and CZT can be used to detect epithermal neutrons in the energy range from 1 up to 66 eV. It was found that the signal-to-background ratio of the measurement can significantly be improved by raising the lower level discrimination threshold on the ? energy to about 600 keV. The advantages/disadvantages of the choice of a Resonance Detector based on YAP or CZT are discussed together with some potential applications.

Tardocchi, M.; Pietropaolo, A.; Andreani, C.; Gorini, G.; Imberti, S.; Perelli-Cippo, E.; Senesi, R.; Rhodes, N.; Schooneveld, E. M.

2006-11-01

210

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. PMID:21626947

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

2011-01-01

211

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

212

The multilayer scintillation detector of high-energy charged particles for satellite experiments  

NASA Astrophysics Data System (ADS)

We present the detection system of high-energy charged particle telescope-spectrometer for space experiment, which is scheduled to take place on the outside the Russian segment of The International Space Station (ISS) and other spacecrafts and small satellites. One of the scientific objectives of experiment is to study electron beams propagation in the magnetosphere. Such a beam can form in acceleration electrons by high-altitude electrical discharge and are injected in the magnetosphere. The detection system for this experiment is developed on the basis of the multilayer scintillation detector (MSD). The MSD is made by polystyrene plates viewed photomultipliers. It can detect 3-30 MeV intense electron beams (up to~105 cm-2s-1) of up several milliseconds, can measure time profiles with accuracy ~ 1 microsecond and energy spectra of particles evolution. MSD's main parameters: geometric factor ~40 cm2·sr, trigger system time resolution ~20 ns, energy resolution 5-10%, angular resolution ~ 10 grad.

Batischev, A.; Aleksandrin, S.; Koldashov, S.; Kuznetcov, A.; Loginov, V.

2013-02-01

213

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

214

A large-area two-dimensional scintillator detector with a wavelength-shifting fibre readout for a time-of-flight single-crystal neutron diffractometer  

NASA Astrophysics Data System (ADS)

A two-dimensional scintillator-based neutron detector that has a neutron-sensitive area of 256×256 mm2 with a pixel size of 4 mm was developed. The detector was designed to be compact and modular with the smallest dead area for the SENJU time-of-flight Laue single-crystal diffractometer to be constructed in the Materials and Life Science Experimental Facility at the Japanese Proton Accelerator Research Complex. The detector employed wavelength-shifting (WLS) fibres to collect scintillation light generated in a neutron-sensitive scintillator. The 64 WLS fibres with a diameter of 1 mm were regularly spaced at a pitch of 4 mm both in the x and y directions to produce a detector with a large neutron-sensitive area and a small number of electronics channels. Two ZnS/10B2O3 scintillator screens with an optimised scintillator thickness sandwiched the cross-arranged WLS fibre arrays to ensure a high detection efficiency for thermal neutrons. The prototype detector exhibited a detector efficiency of 40±1%(mean±SD) for 1.6 Å neutrons and a 60Co gamma-ray sensitivity of 6.0±0.1×10-6, which fulfilled the required detector specifications for SENJU.

Nakamura, T.; Kawasaki, T.; Hosoya, T.; Toh, K.; Oikawa, K.; Sakasai, K.; Ebine, M.; Birumachi, A.; Soyama, K.; Katagiri, M.

2012-09-01

215

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

PubMed

Digital silicon photomultiplier (dSiPM) arrays have favorable characteristics for application in monolithic scintillator detectors for time-of-flight positron emission tomography (PET). To fully exploit these benefits, a maximum likelihood interaction time estimation (MLITE) method was developed to derive the time of interaction from the multiple time stamps obtained per scintillation event. MLITE was compared to several deterministic methods. Timing measurements were performed with monolithic scintillator detectors based on novel dSiPM arrays and LSO:Ce,0.2%Ca crystals of 16 × 16 × 10 mm(3), 16 × 16 × 20 mm(3), 24 × 24 × 10 mm(3), and 24 × 24 × 20 mm(3). The best coincidence resolving times (CRTs) for pairs of identical detectors were obtained with MLITE and measured 157 ps, 185 ps, 161 ps, and 184 ps full-width-at-half-maximum (FWHM), respectively. For comparison, a small reference detector, consisting of a 3 × 3 × 5 mm(3) LSO:Ce,0.2%Ca crystal coupled to a single pixel of a dSiPM array, was measured to have a CRT as low as 120 ps FWHM. The results of this work indicate that the influence of the optical transport of the scintillation photons on the timing performance of monolithic scintillator detectors can at least partially be corrected for by utilizing the information contained in the spatio-temporal distribution of the collection of time stamps registered per scintillation event. PMID:23611889

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

2013-05-21

216

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

217

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

218

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

PubMed Central

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. PMID:22957599

Lessard, Francois; Archambault, Louis; Plamondon, Mathieu; Despres, Philippe; Therriault-Proulx, Francois; Beddar, Sam; Beaulieu, Luc

2012-01-01

219

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

220

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

SciTech Connect

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

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

2004-11-01

221

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

222

An artificial neural network based neutron–gamma discrimination and pile-up rejection framework for the BC501 liquid scintillation detector  

Microsoft Academic Search

BC-501 is a liquid scintillation detector sensitive to both neutrons and gamma rays. As these produce slightly different signals in the detector, they can be discriminated based on their pulse shape (Pulse Shape Discrimination, PSD). This paper reports on results obtained with several PSD techniques and compares them with a method based on artificial neural networks (NN) developed for this

E. Ronchi; P.-A. Söderström; J. Nyberg; E. Andersson Sundén; S. Conroy; G. Ericsson; C. Hellesen; M. Gatu Johnson; M. Weiszflog

2009-01-01

223

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

Microsoft Academic Search

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.

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

2011-01-01

224

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

225

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

NASA Astrophysics Data System (ADS)

In recent years, a new generation of high repetition rate (˜10 Hz), high power (˜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 ˜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.; Karsch, L.; Kraft, S. D.; Pawelke, J.; Richter, C.; Schürer, M.; Sobiella, M.; Stiller, N.; Zeil, K.; Schramm, U.

2012-12-01

226

Results of low energy background measurements with the Liquid Scintillation Detector (LSD) of the Mont Blanc Laboratory  

NASA Astrophysics Data System (ADS)

The 90 tons liquid scintillation detector (LSD) is fully running since October 1984, at a depth of 5,200 hg/sq cm of standard rock underground. The main goal is to search for neutrino bursts from collapsing stars. The experiment is very sensitive to detect low energy particles and has a very good signature to gamma-rays from (n,p) reaction which follows the upsilon e + p yields n + e+ neutrino capture. The analysis of data is presented and the preliminary results on low energy measurements are discussed.

Aglietta, M.; Badino, G.; Bologna, G. F.; Castagnoli, C.; Fulgione, W.; Galeotti, P.; Saavedra, O.; Trinchero, G. C.; Vernetto, S.; Dadykin, V. L.

1985-08-01

227

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

Microsoft Academic Search

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

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

2011-01-01

228

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

E-print Network

A novel algorithm for the discrimination of neutron and {\\gamma}-ray 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 performances of most pulse shape discrimination methods in scintillation detection systems using time-domain features of the pulses are affected intensively by noise. However, the WTMM method using frequency-domain features exhibits a strong insensitivity to noise and can be used to discriminate neutron and {\\gamma}-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 frequency gradient analysis (FGA) method. It is shown that the characterization of neutron and gamma achieved by the discrimination method based on WTMM is consistent with that afforded by TOF and better than FGA. Moreover, because the WTMM method is it self presented to eliminate the noise, there is no need to make any pretreatment for the pulses.

Yang yun; Liu guofu; Yang jun; Luo xiaoliang

2013-04-17

229

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

230

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

PubMed Central

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. PMID:21089762

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

2010-01-01

231

Development of cryogenic phonon detectors based on CaMoO4 and ZnWO4 scintillating crystals for direct dark matter search experiments  

E-print Network

This work reports on the development of the first phonon detectors based on CaMoO4 and ZnWO4 scintillating crystals for the CRESST-II experiment. In particular, a novel technique for the production of the ZnWO4 phonon detector with a separate thermometer carrier was investigated. The influence of the thermal and mechanical treatment on the scintillation light output of CaMoO4 and ZnWO4 crystals at room temperature is discussed.

I. Bavykina; G. Angloher; D. Hauff; M. Kiefer; F. Petricca; F. Proebst

2008-11-12

232

The neutron detectors based on oxide scintillators for control of fissionable radioactive substances  

NASA Astrophysics Data System (ADS)

A large-area X-ray CMOS image sensor (LXCIS) is widely used in mammography, non-destructive inspection, and animal CT. For LXCIS, in spite of weakness such as low spatial and energy resolution, a Indirect method using scintillator like CsI(Tl) or Gd2O2S is still well-used because of low cost and easy manufacture. A photo-diode for X-ray imaging has large area about 50 ~ 200 um as compared with vision image sensors. That is because X-ray has feature of straight and very small light emission of a scintillator. Moreover, notwithstanding several structure like columnar, the scintillator still emit a diffusible light. This diffusible light from scintillator can make spatial crosstalk in X-ray photodiode array because of a large incidence angle. Moreover, comparing with vision image sensors, X-ray sensor doesn't have micro lens for gathering the photons to photo-diode. In this study, we simulated the affection of spatial crosstalk in X-ray sensor by comparing optical sensor. Additionally, the chip, which was fabricated in 0.18 um 1P5M process by Hynix in Korea, was tested to know the effect of spatial crosstalk by changing design parameters. From these works, we found out that spatial crosstalk is affected by pixel pitch, incident angle of photons, and micro lens on each pixels.

Ryzhikov, V. D.; Grinyov, B. V.; Onyshchenko, G. M.; Piven, L. A.; Lysetska, O. K.; Opolonin, O. D.; Kostioukevitch, S. A.; Smith, C. F.

2014-09-01

233

Novel CT detector based on an inorganic scintillator working in photon-counting mode  

Microsoft Academic Search

Detectors working in photon counting mode offer an interesting alternative to the common charge integrating detectors for computed tomography (CT), because they can potentially measure the energy of every detected X-ray photons and achieve better image contrast sensitivity for a given dose. Unfortunately, most current X-ray detectors suffer from limited count rate capability, due either to a long charge migration

Philippe Bérard; Jo Riendeau

2006-01-01

234

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

235

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

236

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

237

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

238

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

239

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

Microsoft Academic Search

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

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

1997-01-01

240

SCINTILLATION DETECTORS FOR MEDICAL AND BIOLOGY APPLICATIONS: MATERIALS, DESIGN AND LIGHT COLLECTION CONDITIONS  

Microsoft Academic Search

Ways for the improvement of operation characteristics are considered for the following scintillators: long LSO(Ce) pixels\\u000a for positron emission tomographs; small prism-shaped CdWO4 crystals for X-ray computer tomography; large thin NaI(Tl) plates for medical gammacameras. The optimization process is based\\u000a on the simulation of light collection process, which involves the choice of the crystal shape, the way of the crystal,

Margaryta Globus; Borys Grinyov

241

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

242

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

243

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

PubMed Central

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

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

2013-01-01

244

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

245

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

246

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

247

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

248

Real-time in vivo rectal wall dosimetry using plastic scintillation detectors for patients with prostate cancer  

NASA Astrophysics Data System (ADS)

We designed and constructed an in vivo dosimetry system using plastic scintillation detectors (PSDs) to monitor dose to the rectal wall in patients undergoing intensity-modulated radiation therapy for prostate cancer. Five patients were enrolled in an Institutional Review Board-approved protocol for twice weekly in vivo dose monitoring with our system, resulting in a total of 142 in vivo dose measurements. PSDs were attached to the surface of endorectal balloons used for prostate immobilization to place the PSDs in contact with the rectal wall. Absorbed dose was measured in real time and the total measured dose was compared with the dose calculated by the treatment planning system on the daily computed tomographic image dataset. The mean difference between measured and calculated doses for the entire patient population was -0.4% (standard deviation 2.8%). The mean difference between daily measured and calculated doses for each patient ranged from -3.3% to 3.3% (standard deviation ranged from 5.6% to 7.1% for four patients and was 14.0% for the last, for whom optimal positioning of the detector was difficult owing to the patient's large size). Patients tolerated the detectors well and the treatment workflow was not compromised. Overall, PSDs performed well as in vivo dosimeters, providing excellent accuracy, real-time measurement and reusability.

Wootton, Landon; Kudchadker, Rajat; Lee, Andrew; Beddar, Sam

2014-02-01

249

Real-time in vivo rectal wall dosimetry using plastic scintillation detectors for patients with prostate cancer.  

PubMed

We designed and constructed an in vivo dosimetry system using plastic scintillation detectors (PSDs) to monitor dose to the rectal wall in patients undergoing intensity-modulated radiation therapy for prostate cancer. Five patients were enrolled in an Institutional Review Board-approved protocol for twice weekly in vivo dose monitoring with our system, resulting in a total of 142 in vivo dose measurements. PSDs were attached to the surface of endorectal balloons used for prostate immobilization to place the PSDs in contact with the rectal wall. Absorbed dose was measured in real time and the total measured dose was compared with the dose calculated by the treatment planning system on the daily computed tomographic image dataset. The mean difference between measured and calculated doses for the entire patient population was -0.4% (standard deviation 2.8%). The mean difference between daily measured and calculated doses for each patient ranged from -3.3% to 3.3% (standard deviation ranged from 5.6% to 7.1% for four patients and was 14.0% for the last, for whom optimal positioning of the detector was difficult owing to the patient's large size). Patients tolerated the detectors well and the treatment workflow was not compromised. Overall, PSDs performed well as in vivo dosimeters, providing excellent accuracy, real-time measurement and reusability. PMID:24434775

Wootton, Landon; Kudchadker, Rajat; Lee, Andrew; Beddar, Sam

2014-02-01

250

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

251

DETECTORS AND EXPERIMENTAL METHODS: Measurement of the neutron spectrum of a Pu-C source with a liquid scintillator  

NASA Astrophysics Data System (ADS)

The neutron response function for a BC501A liquid scintillator (LS) has been measured using a series of monoenergetic neutrons produced by the p-T reaction. The proton energies were chosen such as to produce neutrons in the energy range of 1 to 20 MeV. The principles of the technique of unfolding a neutron energy spectrum by using the measured neutron response function and the measured Pulse Height (PH) spectrum is briefly described. The PH spectrum of neutrons from the Pu-C source, which will be used for the calibration of the reactor antineutrino detectors for the Daya Bay neutrino experiment, was measured and analyzed to get the neutron energy spectrum. Simultaneously the neutron energy spectrum of an Am-Be source was measured and compared with other measurements as a check of the result for the Pu-C source. Finally, an error analysis and a discussion of the results are given.

Wang, Song-Lin; Huang, Han-Xiong; Ruan, Xi-Chao; Li, Xia; Bao, Jie; Nie, Yang-Bo; Zhong, Qi-Ping; Zhou, Zu-Ying; Kong, Xiang-Zhong

2009-05-01

252

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

PubMed

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. PMID:22938315

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

2012-08-01

253

Recent developments in scintillating fiber detection systems in radiation therapy  

NASA Astrophysics Data System (ADS)

Sophisticated radiotherapy techniques lead to more conformal dose distributions but increase treatment complexity. Image guidance allows for varying degrees of accuracy in patient set-up. However, the consequences of inaccurate set-up and/or patient motion during treatment become more serious when treatment doses are increased and treatment margins are decreased. Thus, the need to know if the dose has been delivered as planned has driven the development of plastic scintillation detector systems for accurate measurements in real time with high spatial resolution. We have developed a clinical prototype comprising 29 scintillating fiber detectors 1 mm in diameter and 2 mm in length. The detectors are coupled to clear optical fibers that collect the scintillation photons and transport them to a CCD for detection. Open field profiles and depth-dose profiles in water-equivalent phantoms were compared to ionization chamber measurements in water. The maximum relative in-field difference was 1.6%. With a standard deviation for in-field measurements smaller than 1%, this prototype array was found to be accurate, precise and practical. Monte Carlo simulations were also used to evaluate the response of the scintillation detector to proton beams and to optimize the light collection efficiency. The Monte Carlo code Geant4 was used to simulate dose deposition, the production of scintillation photons and the propagation of those photons inside the scintillation detector. Further development of the system will allow thousands of measurement points distributed in a three-dimensional volume per single irradiation, therefore producing a rapid evaluation of complex dose distributions emanating from these new complex treatment modalities.

Beddar, A. S.; Archambault, L.; Briere, T. M.; Lacroix, F.; Gingras, L.; Beaulieu, L.

2008-03-01

254

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

SciTech Connect

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 {sup 192}Ir 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 [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 and Departement de Physique, de Genie Physique et d'Optique and Centre de Recherche en Cancerologie de l'Universite Laval Universite Laval, Quebec, Quebec G1V 0A6 (Canada); Beddar, Sam [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 and The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030 (United States); Beaulieu, Luc [Departement de Physique, de Genie Physique et d'Optique and Centre de Recherche en Cancerologie de l'Universite Laval Universite Laval, Quebec, Quebec G1V 0A6, Canada and Departement de Radio-Oncologie and Centre de Recherche du CHU de Quebec, CHU de Quebec, Quebec G1R 2J6 (Canada)

2013-06-15

255

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

E-print Network

A cadmium tungstate crystal boule enriched in $^{116}$Cd 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 $^{116}$CdWO$_4$ 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 $^{116}$CdWO$_4$ sample (326 g) was tested with the help of ultra-low background high purity germanium $\\gamma$ detector. Monte Carlo simulations of double $\\beta$ processes in $^{116}$Cd were used to estimate the sensitivity of an experiment to search for double $\\beta$ decay of $^{116}$Cd.

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

2011-08-13

256

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. PMID:23060069

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

2013-01-01

257

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

NASA Astrophysics Data System (ADS)

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. 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. 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. 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. US Patent pending.

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

2012-11-01

258

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

PubMed

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. 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. 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. 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. PMID:23060069

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

2012-11-01

259

Neutron-sensitive ZnS/10B2O3 ceramic scintillator detector as an alternative to a 3He-gas-based detector for a plutonium canister assay system  

NASA Astrophysics Data System (ADS)

A neutron-sensitive ZnS/10B2O3 ceramic scintillator detector was developed as an alternative to a 3He-gas-based detector for use in a plutonium canister assay system. The detector has a modular structure, with a flat ZnS/10B2O3 ceramic scintillator strip that is installed diagonally inside a light-reflecting aluminium case with a square cross-section, and where the scintillation light is detected using two photomultiplier tubes attached at both ends of the case. The prototype detectors, which have a neutron-sensitive area of 30 mm×250 mm, exhibited a sensitivity of 21.7-23.4±0.1 cps/nv (mean±SD) for thermal neutrons, a 137Cs gamma-ray sensitivity of 1.1-1.9±0.2×10-7 and a count variation of less than 6% over the detector length. A trial experiment revealed a temperature coefficient of less than -0.24±0.05%/°C over the temperature range of 20-50 °C. The detector design and the experimental results are presented.

Nakamura, T.; Ohzu, A.; Toh, K.; Sakasai, K.; Suzuki, H.; Honda, K.; Birumachi, A.; Ebine, M.; Yamagishi, H.; Takase, M.; Haruyama, M.; Kureta, M.; Soyama, K.; Nakamura, H.; Seya, M.

2014-11-01

260

Investigation of an in situ position calibration method for continuous crystal-based PET detectors  

NASA Astrophysics Data System (ADS)

The absence of very small crystal pixels in monolithic scintillation detectors has a number of potential advantages such as higher sensitivity, better energy resolution and continuous coordinates. In such detectors, the photon incidence position on the detector surface is derived from the measured scintillation light distribution using artificial neural networks (NNs). To this end, each detector module has to be position-calibrated by training the NNs. An automated procedure to simultaneously obtain the calibration data to train NNs for all detector modules in a fully assembled PET system has been developed and evaluated on a simulator set-up.

Bruyndonckx, Peter; Lemaître, Cedric; Schaart, Dennis; Maas, Marnix; van der Laan, D. J.; Krieguer, Magalie; Devroede, Olivier; Tavernier, Stefaan

2007-02-01

261

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. PMID:23128412

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

2013-01-01

262

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

NASA Astrophysics Data System (ADS)

Plastic scintillation detectors (PSDs) have many advantages over other detectors in small field dosimetry due to their high spatial resolution, excellent water equivalence and instantaneous readout. However, in proton beams, the PSDs undergo a quenching effect which makes the signal level reduced significantly when the detector is close to the 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, ?0.5 mm × 4 mm) 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 the 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.

2012-12-01

263

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

PubMed

Plastic scintillation detectors (PSDs) have many advantages over other detectors in small field dosimetry due to their high spatial resolution, excellent water equivalence and instantaneous readout. However, in proton beams, the PSDs undergo a quenching effect which makes the signal level reduced significantly when the detector is close to the 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, ?0.5 mm × 4 mm) 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 the 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. PMID:23128412

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

2012-12-01

264

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

265

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

266

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

SciTech Connect

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

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

2011-04-15

267

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. PMID:21626951

Therriault-Proulx, Francois; Beddar, Sam; Briere, Tina M.; Archambault, Louis; Beaulieu, Luc

2011-01-01

268

SCINTILLA A European project for the development of scintillation detectors and new technologies for nuclear security  

E-print Network

Europe monitors transits using radiation detectors to prevent illicit trafficking of nuclear materials. The SCINTILLA project aims to develop a toolbox of innovative technologies designed to address different usage cases. This article will review the scope, approach, results of the first benchmark campaign and future plans of the SCINTILLA project.

A. Alemberti; M. Battaglieri; E. Botta; R. De Vita; E. Fanchini; G. Firpo

2014-04-14

269

SCINTILLA A European project for the development of scintillation detectors and new technologies for nuclear security  

E-print Network

Europe monitors transits using radiation detectors to prevent illicit trafficking of nuclear materials. The SCINTILLA project aims to develop a toolbox of innovative technologies designed to address different usage cases. This article will review the scope, approach, results of the first benchmark campaign and future plans of the SCINTILLA project.

Alemberti, A; Botta, E; De Vita, R; Fanchini, E; Firpo, G

2014-01-01

270

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. PMID:21520871

Wang, Lilie L. W.; Beddar, Sam

2011-01-01

271

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

SciTech Connect

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

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

2012-03-15

272

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. PMID:22380355

Archambault, L.; Poenisch, F.; Sahoo, N.; Robertson, D.; Lee, A.; Gillin, M. T.; Mohan, R.; Beddar, S.

2012-01-01

273

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

274

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. PMID:21089789

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

2010-01-01

275

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

PubMed Central

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

Mondal, Nagendra Nath

2009-01-01

276

Achieving a Linear Dose Rate Response in Pulse-Mode Silicon Photodiode Scintillation Detectors Over a Wide Range of Excitations  

NASA Astrophysics Data System (ADS)

We are developing a new dose calibrator for nuclear pharmacies that can measure radioactivity in a vial or syringe without handling it directly or removing it from its transport shield “pig”. The calibrator's detector comprises twin opposing scintillating crystals coupled to Si photodiodes and current-amplifying trans-resistance amplifiers. Such a scheme is inherently linear with respect to dose rate over a wide range of radiation intensities, but accuracy at low activity levels may be impaired, beyond the effects of meager photon statistics, by baseline fluctuation and drift inevitably present in high-gain, current-mode photodiode amplifiers. The work described here is motivated by our desire to enhance accuracy at low excitations while maintaining linearity at high excitations. Thus, we are also evaluating a novel “pulse-mode” analog signal processing scheme that employs a linear threshold discriminator to virtually eliminate baseline fluctuation and drift. We will show the results of a side-by-side comparison of current-mode versus pulse-mode signal processing schemes, including perturbing factors affecting linearity and accuracy at very low and very high excitations. Bench testing over a wide range of excitations is done using a Poisson random pulse generator plus an LED light source to simulate excitations up to ˜106 detected counts per second without the need to handle and store large amounts of radioactive material.

Carroll, Lewis

2014-02-01

277

A design methodology using signal-to-noise ratio for plastic scintillation detectors design and performance optimization  

PubMed Central

Purpose: The design of novel plastic scintillation detectors (PSDs) is impeded by the lack of a suitable framework to simulate and predict their performance. The authors propose to use the signal-to-noise ratio (SNR) to model the performance of PSDs that use charge-coupled devices (CCDs) as photodetectors. Methods: In PSDs using CCDs, the SNR is inversely related to the normalized standard deviation of the dose measurement. Thus, optimizing the SNR directly optimizes the system’s precision. In this work, a model of SNR as a function of the system parameters is derived for optical fiber-based PSD systems. Furthermore, this proposed model is validated using experimental results. A formula for the efficiency of fiber coupling to CCDs is derived and used to simulate the performance of a PSD under varying magnifications. Results: The proposed model is shown to simulate the experimental performance of an actual PSD to a suitable degree of accuracy under various conditions. Conclusions: The SNR constitutes a useful tool to simulate the dosimetric precision of PSDs. Using the SNR model, recommendations for the design and optimization of PSDs are provided. Using the same framework, recommendations for non-fiber-based PSDs are also provided. PMID:19994531

Lacroix, Frederic; Beddar, A. Sam; Guillot, Mathieu; Beaulieu, Luc; Gingras, Luc

2009-01-01

278

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

PubMed Central

Purpose: This work presents the experimental extraction of the overall perturbation factor PQ 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 R50 of approximately 0.4 mm at 6 MeV, 1.0 mm at 12 MeV, and 1.2 mm at 18 MeV. PMID:20879593

Lacroix, Frederic; Guillot, Mathieu; McEwen, Malcolm; Cojocaru, Claudiu; Gingras, Luc; Beddar, A. Sam; Beaulieu, Luc

2010-01-01

279

Upgrade of the POLDI diffractometer with a ZnS(Ag)/6LiF scintillation detector read out with WLS fibers coupled to SiPMs  

NASA Astrophysics Data System (ADS)

A thermal neutron detector based on ZnS(Ag)/6LiF scintillator, wavelength- shifting fibers (WLS) and silicon photomultipliers (SiPM) is under development at the Paul Scherrer Institute (PSI) for upgrading the POLDI instrument, a pulse-overlap diffractometer. The design of the detector is outlined, and the measurements performed on a single channel prototype are presented. An innovative signal processing system based on a photon counting approach is under development. Its principle of operation is described and its performances are evaluated on the basis of a Monte Carlo simulation.

Mosset, J.-B.; Stoykov, A.; Davydov, V.; Hildebrandt, M.; Van Swygenhoven, H.; Wagner, W.

2014-07-01

280

Determination of optimal boundary for algorithmic method of plastic scintillator-based radiation detector against nuclear terrorism  

Microsoft Academic Search

A plastic scintillator-based radiation portal monitoring system has played an important role in preventing and detecting illicit trafficking of nuclear and radioactive materials. The limited spectroscopic information of the plastic scintillator material makes it difficult to discriminate radioactive materials of concern from naturally occurring radioactive materials (NORM) or background radiation. This has an impact on operations and surveillance costs. Various

Sung-Woo Kwak; Sung Soon Jang; Ho-Sik Yoo

2010-01-01

281

Development of a scintillating G-GEM detector for a 6-MeV X-band Linac for medical applications  

NASA Astrophysics Data System (ADS)

We recently developed glass gas electron multipliers (G-GEMs) with an entirely new process using photo-etchable glass. The photo-etchable glass used for the substrate is called PEG3 (Hoya Corporation). Taking advantage of low outgassing material, we have envisioned a medical application of G-GEMs. A two-dimensional position-sensitive dosimetry system based on a scintillating gas detector is being developed for real-time dose distribution monitoring in X-ray radiation therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside of which G-GEM structures are mounted. Photons produced by the excited Ar/CF4 gas molecules during the gas multiplication in the GEM holes are detected by a mirror-lens-CCD-camera system. We found that the intensity distribution of the measured light spot is proportional to the 2D dose distribution. In this work, we report on the first results from a scintillating G-GEM detector for a position-sensitive X-ray beam dosimeter.

Fujiwara, T.; Tanaka, S.; Mitsuya, Y.; Takahashi, H.; Tagi, K.; Kusano, J.; Tanabe, E.; Yamamoto, M.; Nakamura, N.; Dobashi, K.; Tomita, H.; Uesaka, M.

2013-12-01

282

Characterization of the SIDDHARTA-2 second level trigger detector prototype based on scintillators coupled to a prism reflector light guide  

NASA Astrophysics Data System (ADS)

The SIDDHARTA experiment at the DA?NE collider of LNF-INFN performed in 2009 high precision measurements of kaonic hydrogen and kaonic helium atomic transitions. To determine the bar KN isospin dependent scattering lenghts an important measurement, namely the kaonic deuterium one, is, however, still missing. Due to the very low expected yield of the kaonic deuterium K? transition, a major improvement in the signal over background ratio is needed. To achieve a further background reduction, a second level trigger, based on the detection of charged pions produced by the K- absorption on various materials, including the target gas nuclei, is planned to be implemented in the future SIDDHARTA-2 experiment. For shielding-related geometrical limitations, a single side of the scintillators can be accessed; in order to reach a good time resolution and uniform efficiency, a both-end readout was then realized with complex multi-reflection light guides. In this work, the results of the tests made on a detector prototype, performed on the ?M-1 beamline of the Paul Scherrer Institute (Switzerland), are presented. The tests had the goal to determine the efficiency and the time resolution for pions, which should comply with the minimum required values of 90% and 1 ns (FWHM) respectively. The obtained results, 96% efficiency and 750 ps FWHM for 170 MeV/c momentum pions, qualify the prototype as an excellent second level trigger for the SIDDHARTA-2 experiment. Similar results for 170 MeV/c momentum muons and electrons are also presented.

Bazzi, M.; Berucci, C.; Curceanu, C.; d'Uffizi, A.; Iliescu, M.; Sbardella, E.; Scordo, A.; Shi, H.; Sirghi, F.; Tatsuno, H.; Tucakovic, I.

2013-11-01

283

Investigation of crystal surface finish and geometry on single LYSO scintillator detector performance for depth-of-interaction measurement with silicon photomultipliers  

NASA Astrophysics Data System (ADS)

Depth of Interaction (DOI) information can improve quality of reconstructed images acquired from Positron Emission Tomography (PET), especially in high resolution and compact scanners dedicated for breast, brain, or small animal imaging applications. Additionally, clinical scanners with time of flight capability can also benefit from DOI information. One of the most promising methods of determining DOI in a crystal involves reading the signal from two ends of a scintillation crystal, and calculating the signal ratio between the two detectors. This method is known to deliver a better DOI resolution with rough crystals compared to highly polished crystals. However, what is still not well studied is how much of a tradeoff is involved between spatial, energy, temporal, and DOI resolutions as a function of the crystal surface treatment and geometry with the use of Silicon Photomultipliers (SiPM) as the photo detectors. This study investigates the effects of different crystal surface finishes and geometries on energy, timing and DOI resolutions at different crystal depths. The results show that for LYSO scintillators of 1.5×1.5×20 mm3 and 2×2×20 mm3 with their surfaces finished from 0.5 to 30 ?m roughness, almost the same energy and coincidence timing resolutions were maintained, around 15% and 2.4 ns, respectively across different crystal depths, while the DOI resolutions were steadily improved from worse than 5 mm to better than 2 mm. They demonstrate that crystal roughness, with proper surface preparing, does not have a significant effect on the energy and coincidence timing resolutions in the crystals examined, and there does not appear to be a tradeoff between improving DOI resolution and degrading other detector performances. These results will be valuable to guide the selection of crystal surface conditions for developing a DOI measurable PET detector with a full array of LYSO scintillators coupled to SiPM arrays.

Bircher, Chad; Shao, Yiping

2012-11-01

284

Results from the SPI Imaging Test Setup  

NASA Astrophysics Data System (ADS)

The SPI Imaging Test Setup (SPITS) was built at MPE to allow experimental verification of the imaging properties of the Spectrometer onboard INTEGRAL (SPI). Of special importance is the possibility to validate simulations which are needed for SPI image reconstruction with laboratory measurements. SPITS consists of a coded mask and two Germanium detectors. The coded mask is based on a SPI mask development model, has the same Tungsten-alloy HURA mask coding as SPI, and is made of SPI flight model materials. The two hexagonal Ge-detectors in their Al caps (each 6 cm sideto-side and 7 cm long) are from the same manufacturing line as the SPI flight detectors. They are housed in a common Al end cap and cooled with liquid nitrogen. Mounted on an XY-table, they can be moved to cover the 19 Ge detector positions of the SPI camera. The SPI plastic scintillator anticoincidence is replaced by a plexiglass sheet, and no BGO anticoincidence system is used. We have measured the response of SPITS to radioactive sources (60 keV to 1.8 MeV) at a distance of 9 m from the detector plane. We use both image deconvolution algorithms foreseen for SPI data analysis (spiros and spiskymax) for our analysis. In addition, accelerator tests are planned for May 2001. Photons from (p,?)-reactions (up to 9 MeV) will be used to test SPITS imaging capabilites. We present our findings for the angular resolution and the point-source-location capability of SPITS as a function of energy and for different source geometries relative to the mask coding. Thus SPITS results complement the calibration performed with the flight model of SPI.

Wunderer, C. B.; Diehl, R.; Georgii, R.; Kienlin, A. V.; Lichti, G. G.; Schoenfelder, V.; Strong, A.; Connell, P.; Hammer, J. W.; Sanchez, F.; Vedrenne, G.

2001-08-01

285

Taheri-Saramad x-ray detector (TSXD): A novel high spatial resolution x-ray imager based on ZnO nano scintillator wires in polycarbonate membrane  

NASA Astrophysics Data System (ADS)

A novel x-ray imager based on ZnO nanowires is designed and fabricated. The proposed architecture is based on scintillation properties of ZnO nanostructures in a polycarbonate track-etched membrane. Because of higher refractive index of ZnO nanowire compared to the membrane, the nanowire acts as an optical fiber that prevents the generated optical photons to spread inside the detector. This effect improves the spatial resolution of the imager. The detection quantum efficiency and spatial resolution of the fabricated imager are 11% and <6.8 ?m, respectively.

Taheri, A.; Saramad, S.; Ghalenoei, S.; Setayeshi, S.

2014-01-01

286

Prompt ? radiation measured with a Nal scintillation detector: a beam monitor for neutron scattering instruments which needs no space in the beam  

NASA Astrophysics Data System (ADS)

We investigate the possibility of using the prompt ? rays emitted by aluminum windows in order to monitor the neutron flux of the beam. A Nal scintillation detector is used to detect the prompt ? rays. No additional material apart from the unavoidable Al windows along the flight path is placed in the beam. The performance of the monitor is compared to that of a standard BF3-monitor placed in the beam. Influences of a magnetic field on the photomultiplier of the Nal monitor is discussed, as well as the influence of activation gammas. At an instrument using a beam chopper the time behaviour is discussed.

Holderer, O.; Zamponi, M.; Monkenbusch, M.; Engels, R.

2014-07-01

287

Evaluation of a setup for pNRA at LIBAF for applications in geosciences  

NASA Astrophysics Data System (ADS)

A new setup for photon tagged nuclear reaction analysis pNRA is being developed at Lund's ion beam analysis facility LIBAF. Particle induced gamma ray emission PIGE and nuclear reaction analysis NRA are two methods that have been extensively used for light isotope measurement in ion beam analysis IBA. There is an abundance of nuclear reactions between light elements and MeV protons, deuterons and alpha particles. This means that in principle all elements from lithium all the way up to chlorine can be analyzed using those techniques. Detection limits can be improved for some elements, if those two methods are fused together into pNRA. The new setup for pNRA will benefit from advances in detector technology that occurred during the last 20 years. A LaBr3 scintillator detector and an annular double sided silicon strip detector DSSSD are used in coincidence to detect a gamma and a charged particle respectively. Both detectors are connected to a VME based data acquisition system. Of primary interest in this work is the analysis of isotopic ratios of light elements in geological samples, which are usually thick with a complex matrix. This setup can be for instance used to measure isotopic fractionation of oxygen and boron. We will present the setup and discuss its capabilities.

Borysiuk, M.; Kristiansson, P.; Ros, L.; Abdel, N.; Elfman, M.; Nilsson, E. J. C.; Pallon, J.

2014-08-01

288

Measurements of high energy neutrons penetrated through iron shields using the Self-TOF detector and an NE213 organic liquid scintillator  

NASA Astrophysics Data System (ADS)

Neutron energy spectra penetrated through iron shields were measured using the Self-TOF detector and an NE213 organic liquid scintillator which have been newly developed by our group at the Heavy-Ion Medical Accelerator in Chiba (HIMAC) of National Institute of Radiological Sciences (NIRS), Japan. Neutrons were generated by bombarding 400 MeV/nucleon C ion on a thick (stopping-length) copper target. The neutron spectra in the energy range from 20 to 800 MeV were obtained through the FORIST unfolding code with their response functions and compared with the MCNPX calculations combined with the LA150 cross section library. The neutron fluence measured by the NE213 detector was simulated by the track length estimator in the MCNPX, and evaluated the contribution of the room-scattered neutrons. The calculations are in fairly good agreement with the measurements. Neutron fluence attenuation lengths were obtained from the experimental results and the calculation.

Sasaki, M.; Nakao, N.; Nunomiya, T.; Nakamura, T.; Fukumura, A.; Takada, M.

2002-11-01

289

An artificial neural network based neutron-gamma discrimination and pile-up rejection framework for the BC-501 liquid scintillation detector  

NASA Astrophysics Data System (ADS)

BC-501 is a liquid scintillation detector sensitive to both neutrons and gamma rays. As these produce slightly different signals in the detector, they can be discriminated based on their pulse shape (Pulse Shape Discrimination, PSD). This paper reports on results obtained with several PSD techniques and compares them with a method based on artificial neural networks (NN) developed for this application. Results indicated a large performance advantage of NN especially in the region of small deposited energy which typically contains the majority of the events. NN were also applied for discrimination of pile-up events with good results. This framework can be implemented on some of the most recent programmable data acquisition cards and it is suitable for real-time application.

Ronchi, E.; Söderström, P.-A.; Nyberg, J.; Andersson Sundén, E.; Conroy, S.; Ericsson, G.; Hellesen, C.; Gatu Johnson, M.; Weiszflog, M.

2009-11-01

290

3D Printing of Scintillating Materials  

E-print Network

We demonstrate, for the first time, the applicability of 3D printing technique to the manufacture of scintillation detectors. We report of a formulation, usable in stereolithographic printing, that exhibits scintillation efficiency on the order of 30\\% of that of commercial polystyrene based scintillators. We discuss the applicability of these techniques and propose future enhancements that will allow tailoring the printed scintillation detectors to various application.

Y. Mishnayot; M. Layani; I. Cooperstein; S. Magdassi; G. Ron

2014-06-15

291

3D Printing of Scintillating Materials  

E-print Network

We demonstrate, for the first time, the applicability of 3D printing technique to the manufacture of scintillation detectors. We report of a formulation, usable in stereolithographic printing, that exhibits scintillation efficiency on the order of 30\\% of that of commercial polystyrene based scintillators. We discuss the applicability of these techniques and propose future enhancements that will allow tailoring the printed scintillation detectors to various application.

Mishnayot, Y; Cooperstein, I; Magdassi, S; Ron, G

2014-01-01

292

Scintillator Waveguide For Sensing Radiation  

DOEpatents

The present invention is an apparatus for detecting ionizing radiation, having: a waveguide having a first end and a second end, the waveguide formed of a scintillator material wherein the therapeutic ionizing radiation isotropically generates scintillation light signals within the waveguide. This apparatus provides a measure of radiation dose. The apparatus may be modified to permit making a measure of location of radiation dose. Specifically, the scintillation material is segmented into a plurality of segments; and a connecting cable for each of the plurality of segments is used for conducting scintillation signals to a scintillation detector.

Bliss, Mary (West Richland, WA); Craig, Richard A. (West Richland, WA); Reeder; Paul L. (Richland, WA)

2003-04-22

293

A direct method for evaluating the concentration of boric acid in a fuel pool using scintillation detectors for joint-multiplicity measurements  

NASA Astrophysics Data System (ADS)

The present investigations are aimed at the development of a direct passive non-intrusive method for determining the concentration of boric acid in a spent fuel pool using scintillation detectors with the purpose of correcting joint-multiplicity measurement results. The method utilizes a modified relation between two gamma lines with energy of 480 keV and 2.23 MeV, respectively. The gamma line at 480 keV belongs to the thermal neutron capture in boron. The 2.23 MeV gamma line characterizes the capture of thermal neutrons in hydrogen. Thus, the relation between them can reveal the concentration of the boron in the fuel pool. In order to test this method, first MCNPX and MCNP-PoliMi simulations were performed. Then, based on the results of Monte Carlo simulations, the method was verified by an experimental study with a 241Am-Be source and EJ-309 scintillation detectors. The concentration of boron in water varied from 1550 ppm to 4000 ppm. The results of these tests are provided in the paper and they show that the spectral ratio between these two lines can in principle be used to determine the boron content.

Chernikova, Dina; Axell, Kåre; Pázsit, Imre; Nordlund, Anders; Sarwar, Rashed

2013-06-01

294

Direct Deposition of Microcolumnar Scintillator on CMOS SSPM Array: Toward a Photon Counting Detector for X-Ray/Gamma Ray Imaging  

SciTech Connect

We are developing a modular, low-cost, photon-counting detector based on a scintillator coupled to a solid-state photodetector. A working prototype was successfully developed by depositing CsI:Tl directly onto a CMOS SSPM array designed by RMD and custom-fabricated by a commercial foundry. The device comprised a 6x6 array of 1.5x1.5 mm{sup 2} macro-pixels, each containing a 36x36 array of resistively coupled micro-pixels, that was subjected to vapor deposition of columnar CsI:Tl. Direct deposition eliminates the gap between the scintillator and SSPM and creates a better optical bond than does index-matching grease. This paper compares the performance of SSPMs with directly deposited CsI:Tl, in terms of signal-to-noise ratio and light spread, against devices using monolithic single crystals or pixelated single crystals coupled to the SSPM. Due to the reduction in light scattering and optical losses in the interface, the directly deposited CsI:Tl demonstrated significantly better position sensitivity, with at least a factor of 2 increase in SNR compared to a single crystal. These data indicate that a photodetector with substantially smaller macro-pixel dimensions than used here could be used to implement a low-energy X-ray/gamma-ray imaging and spectroscopy detector, particularly for applications where high resolution is of prime importance.

Prekas, G.; Breen, M.; Sabet, H.; Bhandari, H.; Derderian, G.; Robertson, F. Jr; Stapels, C. J.; Christian, J.; Cool, S.; Nagarkar, V. V. [Radiation Monitoring Devices, Inc., 44 Hunt Street, Watertown, Massachusetts 02472 (United States)

2011-12-13

295

Photofraction of a 5 cm x 2 cm BGO scintillator. [bismuth germanate crystal for use in cosmic gamma ray detector  

NASA Technical Reports Server (NTRS)

The photofraction of a 5.1 cm x 2.0 cm bismuth germanate (BGO) scintillator was measured over a gamma-ray energy range of 0.2 to 6.1 MeV. Several methods, used to minimize the effect of room scattering on the measurement, are discussed. These include a gamma-gamma coincidence technique, a beta-gamma coincidence technique, and the use of sources calibrated with a standard 7.6 cm x 7.6 cm sodium iodide scintillator.

Dunphy, P. P.; Forrest, D. J.

1985-01-01

296

Comparison of Cadmium–Zinc–Telluride semiconductor and Yttrium–Aluminum–Perovskite scintillator as photon detectors for epithermal neutron spectroscopy  

Microsoft Academic Search

The range of applications of epithermal neutron scattering experiments has been recently extended by the development of the Resonance Detector. In a Resonance Detector, resonant neutron absorption in an analyzer foil results in prompt emission of X- and ?-rays which are detected by a photon counter. Several combinations of analyzer foils and photon detectors have been studied and tested over

M. Tardocchi; A. Pietropaolo; C. Andreani; G. Gorini; S. Imberti; E. Perelli-Cippo; R. Senesi; N. Rhodes; E. M. Schooneveld

2006-01-01

297

A semi-empirical Monte Carlo based model of the Detector Optical Gain of Nuclear Imaging scintillators  

NASA Astrophysics Data System (ADS)

This paper reports a theoretical model of the optical gain of single-crystal scintillators of Nuclear Imaging. The model described the generation, propagation and escape of scintillation light as function of thickness and absorbed gamma ray energy. The latter was calculated via Monte Carlo methods at various crystal depths. The energies of 140 keV, 364 keV and 512 keV were investigated. The adopted thickness and energy values cover the range utilized in nuclear medicine imaging. For the semi-empirical approach, theoretical results were compared to experimental data for photon energies of 140 keV and 364 keV and the model's optical parameters were determined by the trial and error method. The results rendered the calculation of the optimum crystal thickness per investigated gamma ray energy. The presented results could be useful in designing nuclear medicine imaging systems.

Nikolopoulos, D.; Kalyvas, N.; Valais, I.; Argyriou, X.; Vlamakis, E.; Sevvos, T.; Kandarakis, I.

2012-11-01

298

DETECTORS AND EXPERIMENTAL METHODS: Measurement of the response function and the detection efficiency of an organic liquid scintillator for neutrons between 1 and 30 MeV  

NASA Astrophysics Data System (ADS)

The light output function of a varphi50.8 mm × 50.8 mm BC501A scintillation detector was measured in the neutron energy region of 1 to 30 MeV by fitting the pulse height (PH) spectra for neutrons with the simulations from the NRESP code at the edge range. Using the new light output function, the neutron detection efficiency was determined with two Monte-Carlo codes, NEFF and SCINFUL. The calculated efficiency was corrected by comparing the simulated PH spectra with the measured ones. The determined efficiency was verified at the near threshold region and normalized with a Proton-Recoil-Telescope (PRT) at the 8-14 MeV energy region.

Huang, Han-Xiong; Ruan, Xi-Chao; Chen, Guo-Chang; Zhou, Zu-Ying; Li, Xia; Bao, Jie; Nie, Yang-Bo; Zhong, Qi-Ping

2009-08-01

299

Response of NE213 liquid scintillation detectors to high-energy photons (7 MeV < E? < 20 MeV)  

NASA Astrophysics Data System (ADS)

Two NE213 liquid scintillation detectors of 206 and 412 cm 3 in volume were calibrated in high-energy photon fields ( E? > 7 MeV) at the PTB accelerator facility. The measured pulse height spectra are in excellent agreement with the response functions simulated with the EGS4 Monte Carlo code. The generally assumed linear dependence of the electron light output on the energy deposited does not hold for electron energies above 1.6 MeV. The nonlinear electron light output function was therefore included in the calculation of the response functions. The production of high-energy electrons and positrons in the target assembly and in the air was also taken into consideration.

Novotny, T.; Büermann, L.; Guldbakke, S.; Klein, H.

1997-02-01

300

Assessment of photon detectors for a handheld gamma-ray and neutron spectrometer using Cs2LiYCl6:Ce (CLYC) scintillator  

NASA Astrophysics Data System (ADS)

The coupling of Cs2LiYCl6:Ce (CLYC) scintillator to silicon photon converters has been evaluated with the goal of investigating replacements for the traditional photomultiplier tube (PMT) in small handheld spectrometers. Energy spectra produced under irradiation by a range of gamma-ray and neutron sources were collected with CLYC mounted to several avalanche photodiodes, PIN photodiodes, and silicon photomultipliers. The performance for both gamma rays and neutrons was compared to that obtained by coupling CLYC to PMTs. None of the silicon devices evaluated provide comparable performance to that of a PMT with CLYC. This is attributed to the photon-detection efficiency of the silicon detectors over the wavelength range of CLYC emissions, as well as the noise characteristics of the devices.

Smith, M. B.; McClish, M.; Achtzehn, T.; Andrews, H. R.; Baginski, M. J.; Best, D. J.; Budden, B. S.; Clifford, E. T. H.; Dallmann, N. A.; Dathy, C.; Frank, J. M.; Graham, S. A.; Ing, H.; Stonehill, L. C.

2013-07-01

301

A scintillator-based detector with sub-100-?m spatial resolution comprising a fibre-optic taper with wavelength-shifting fibre readout for time-of-flight neutron imaging  

NASA Astrophysics Data System (ADS)

A scintillator-based neutron-counting imaging detector with a sub-100-?m spatial resolution was developed for energy-selective neutron imaging. The detector head of the detector comprised a thin ZnS/6LiF scintillator screen, a fibre-optic taper and crossed wavelength-shifting (WLS) fibre arrays. A high spatial resolution was achieved by constructing the scintillator with a thickness of 100 ?m and placing it in contact with the fibre-optic taper at a magnification ratio of 3.1:1. WLS fibres with a diameter of 100±5 ?m (mean±SD) were specially made, and their dye content was optimized for use in crossed WLS-fibre arrays. The developed detector had a pixel size of 34 ?m×34 ?m, and exhibited spatial FWHM resolutions of 80±7 ?m and 61±6 ?m in the x and y directions, respectively. A small prototype detector demonstrated the capability of neutron imaging using Bragg edges of a Cu/Fe sample when using the pulsed-neutron source in the Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex.

Nakamura, T.; Toh, K.; Kawasaki, T.; Honda, K.; Suzuki, H.; Ebine, M.; Birumachi, A.; Sakasai, K.; Soyama, K.; Katagiri, M.

2014-02-01

302

Nanophosphor composite scintillator with a liquid matrix  

DOEpatents

An improved nanophosphor scintillator liquid comprises nanophosphor particles in a liquid matrix. The nanophosphor particles are optionally surface modified with an organic ligand. The surface modified nanophosphor particle is essentially surface charge neutral, thereby preventing agglomeration of the nanophosphor particles during dispersion in a liquid scintillator matrix. The improved nanophosphor scintillator liquid may be used in any conventional liquid scintillator application, including in a radiation detector.

McKigney, Edward Allen (Los Alamos, NM); Burrell, Anthony Keiran (Los Alamos, NM); Bennett, Bryan L. (Los Alamos, NM); Cooke, David Wayne (Santa Fe, NM); Ott, Kevin Curtis (Los Alamos, NM); Bacrania, Minesh Kantilal (Los Alamos, NM); Del Sesto, Rico Emilio (Los Alamos, NM); Gilbertson, Robert David (Los Alamos, NM); Muenchausen, Ross Edward (Los Alamos, NM); McCleskey, Thomas Mark (Los Alamos, NM)

2010-03-16

303

Scintillator materials containing lanthanum fluorides  

DOEpatents

An improved radiation detector containing a crystalline mixture of LaF[sub 3] and CeF[sub 3] as the scintillator element is disclosed. Scintillators made with from 25% to 99.5% LaF[sub 3] and the remainder CeF[sub 3] have been found to provide a balance of good stopping power, high light yield and short decay constant that is equal to or superior to other known scintillator materials, and which may be processed from natural starting materials containing both rare earth elements. The radiation detectors disclosed are favorably suited for use in general purpose detection and in positron emission tomography. 2 figures.

Moses, W.W.

1991-05-14

304

Scintillator materials containing lanthanum fluorides  

DOEpatents

An improved radiation detector containing a crystalline mixture of LaF.sub.3 and CeF.sub.3 as the scintillator element is disclosed. Scintillators made with from 25% to 99.5% LaF.sub.3 and the remainder CeF.sub.3 have been found to provide a balance of good stopping power, high light yield and short decay constant that is equal to or superior to other known scintillator materials, and which may be processed from natural starting materials containing both rare earth elements. The radiation detectors disclosed are favorably suited for use in general purpose detection and in positron emission tomography.

Moses, William W. (Berkeley, CA)

1991-01-01

305

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

SciTech Connect

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

Guillot, Mathieu; Beaulieu, Luc; Archambault, Louis; Beddar, Sam; Gingras, 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 MD 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, Quebec G1R 2J6 (Canada)

2011-12-15

306

A technique for verifying the input response function of neutron time-of-flight scintillation detectors using cosmic raysa)  

NASA Astrophysics Data System (ADS)

An accurate interpretation of DD or DT fusion neutron time-of-flight (nTOF) signals from current mode detectors employed at the Z-facility at Sandia National Laboratories requires that the instrument response functions (IRF's) be deconvolved from the measured nTOF signals. A calibration facility that produces detectable sub-ns radiation pulses is typically used to measure the IRF of such detectors. This work, however, reports on a simple method that utilizes cosmic radiation to measure the IRF of nTOF detectors, operated in pulse-counting mode. The characterizing metrics reported here are the throughput delay and full-width-at-half-maximum. This simple approach yields consistent IRF results with the same detectors calibrated in 2007 at a LINAC bremsstrahlung accelerator (Idaho State University). In particular, the IRF metrics from these two approaches and their dependence on the photomultipliers bias agree to within a few per cent. This information may thus be used to verify if the IRF for a given nTOF detector employed at Z has changed since its original current-mode calibration and warrants re-measurement.

Bonura, M. A.; Ruiz, C. L.; Fehl, D. L.; Cooper, G. W.; Chandler, G.; Hahn, K. D.; Nelson, A. J.; Styron, J. D.; Torres, J. A.

2014-11-01

307

A new experimental setup established for low-energy nuclear astrophysics studies  

NASA Astrophysics Data System (ADS)

An experimental setup for low-energy nuclear astrophysics studies has been recently established at the Institute of Modern Physics (IMP), Lanzhou, China. The driver machine is a 320 kV high voltage platform, which can provide intense currents of proton, alpha and many heavy ion beams. The energy of a proton beam was calibrated against the nominal platform high voltage by using a well-known resonant reaction of 11B(p,?)12C and a non-resonant reaction 12C(p,?)13N. The accuracy was achieved to be better than ±0.5 keV. The detection system consists of a Clover-type high-purity germanium detector, a silicon detector and a plastic scintillator. The performance of the detectors was tested by several experiments. The astrophysical S-factors of the 7Li(p,?)8Be and 7Li(p,?)3He reactions were measured with this new setup, and our data agree with the values found in the literature. In addition, the upgrade of our driver machine and experimental setup has been discussed. As a future goal, a fascinating National Deep Underground Laboratory in China, the deepest underground laboratory all over the world, is prospected.

Chen, S. Z.; Xu, S. W.; He, J. J.; Hu, J.; Rolfs, C. E.; Zhang, N. T.; Ma, S. B.; Zhang, L. Y.; Hou, S. Q.; Yu, X. Q.; Ma, X. W.

2014-01-01

308

Indirect flat-panel detector with avalanche gain: Fundamental feasibility investigation for SHARP-AMFPI (scintillator HARP active matrix flat panel imager)  

SciTech Connect

An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The final electronic image is read out using an active matrix array of thin film transistors (TFT). We call the proposed detector SHARP-AMFPI (scintillator HARP active matrix flat panel imager). The advantage of the SHARP-AMFPI is its programmable gain, which can be turned on during low dose fluoroscopy to overcome electronic noise, and turned off during high dose radiography to avoid pixel saturation. The purpose of this paper is to investigate the important design considerations for SHARP-AMFPI such as avalanche gain, which depends on both the thickness d{sub Se} and the applied electric field E{sub Se} of the HARP layer. To determine the optimal design parameter and operational conditions for HARP, we measured the E{sub Se} dependence of both avalanche gain and optical quantum efficiency of an 8 {mu}m HARP layer. The results were used in a physical model of HARP as well as a linear cascaded model of the FPI to determine the following x-ray imaging properties in both the avalanche and nonavalanche modes as a function of E{sub Se}: (1) total gain (which is the product of avalanche gain and optical quantum efficiency); (2) linearity; (3) dynamic range; (4) gain nonuniformity resulting from thickness nonuniformity; and (5) effects of direct x-ray interaction in HARP. Our results showed that a HARP layer thickness of 8 {mu}m can provide adequate avalanche gain and sufficient dynamic range for x-ray imaging applications to permit quantum limited operation over the range of exposures needed for radiography and fluoroscopy.

Zhao Wei; Li Dan; Reznik, Alla; Lui, B.J.M.; Hunt, D.C.; Rowlands, J.A.; Ohkawa, Yuji; Tanioka, Kenkichi [Department of Radiology, State University of New York at Stony Brook, L-4, 120 Health Sciences Center Stony Brook, New York 11793-8460 (United States); Imaging Research, Sunnybrook and Women's Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5 (Canada); Advanced Imaging Devices Research Division, Science and Technical Research Laboratories, Japan Broadcasting Corporation, 1-10-11 Kinuta, Setagaya-ku, Tokyo 157-8510 (Japan)

2005-09-15

309

A compact and high sensitivity positron detector using dual-layer thin GSO scintillators for a small animal PET blood sampling system.  

PubMed

For quantitative measurements of small animals such as mice or rats, a compact and high sensitivity continuous blood sampling detector is required because their blood sampling volume is limited. For this purpose we have developed and tested a new positron detector. The positron detector uses a pair of dual-layer thin gadolinium orthosilicate (GSO) scintillators with different decay times. The front layer detects the positron and the background gamma photons, and the back layer detects the background gamma photons. By subtracting the count rate of the latter from that of the former, the count rate of the positrons can be estimated. The GSO for the front layer has a Ce concentration of 1.5 mol% (decay time of 35 ns), and that for the back layer has a Ce concentration of 0.5 mol% (decay time of 60 ns). By using the pulse shape analysis, the count rate of these two GSOs can be discriminated. The thickness is 0.5 mm, which is thick enough to detect positrons while minimizing the detection of the background gamma photons. These two types of thin GSOs were optically coupled to each other and connected to a metal photomultiplier tube (PMT) through triangular light guides. The signal from the PMT was digitized by 100 MHz free-running A-D converters in the data acquisition system and digitally integrated at two different integration times for the pulse shape analysis. We obtained good separation of the pulse shape distributions of these two GSOs. The energy threshold level was decreased to 80 keV, increasing the sensitivity of the detector. The sensitivity of a small diameter plastic tube was 8.6% and 24% for the F-18 and C-11 positrons, respectively. The count rate performance was linear up to approximately 50 kcps. The background counts from the gamma photons could be precisely corrected. The time-activity curve (TAC) of the rat artery blood was successfully obtained and showed a good correlation with that measured using a well counter. With these results, we confirmed that the developed blood sampling detector is promising for quantitative measurement for an animal positron emission tomography system. PMID:20551500

Yamamoto, Seiichi; Imaizumi, Masao; Shimosegawa, Eku; Kanai, Yasukazu; Sakamoto, Yusuke; Minato, Kotaro; Shimizu, Keiji; Senda, Michio; Hatazawa, Jun

2010-07-01

310

A compact and high sensitivity positron detector using dual-layer thin GSO scintillators for a small animal PET blood sampling system  

NASA Astrophysics Data System (ADS)

For quantitative measurements of small animals such as mice or rats, a compact and high sensitivity continuous blood sampling detector is required because their blood sampling volume is limited. For this purpose we have developed and tested a new positron detector. The positron detector uses a pair of dual-layer thin gadolinium orthosilicate (GSO) scintillators with different decay times. The front layer detects the positron and the background gamma photons, and the back layer detects the background gamma photons. By subtracting the count rate of the latter from that of the former, the count rate of the positrons can be estimated. The GSO for the front layer has a Ce concentration of 1.5 mol% (decay time of 35 ns), and that for the back layer has a Ce concentration of 0.5 mol% (decay time of 60 ns). By using the pulse shape analysis, the count rate of these two GSOs can be discriminated. The thickness is 0.5 mm, which is thick enough to detect positrons while minimizing the detection of the background gamma photons. These two types of thin GSOs were optically coupled to each other and connected to a metal photomultiplier tube (PMT) through triangular light guides. The signal from the PMT was digitized by 100 MHz free-running A-D converters in the data acquisition system and digitally integrated at two different integration times for the pulse shape analysis. We obtained good separation of the pulse shape distributions of these two GSOs. The energy threshold level was decreased to 80 keV, increasing the sensitivity of the detector. The sensitivity of a small diameter plastic tube was 8.6% and 24% for the F-18 and C-11 positrons, respectively. The count rate performance was linear up to ~50 kcps. The background counts from the gamma photons could be precisely corrected. The time-activity curve (TAC) of the rat artery blood was successfully obtained and showed a good correlation with that measured using a well counter. With these results, we confirmed that the developed blood sampling detector is promising for quantitative measurement for an animal positron emission tomography system.

Yamamoto, Seiichi; Imaizumi, Masao; Shimosegawa, Eku; Kanai, Yasukazu; Sakamoto, Yusuke; Minato, Kotaro; Shimizu, Keiji; Senda, Michio; Hatazawa, Jun

2010-07-01

311

Composite CaWO{sub 4} Detectors for the CRESST-II Experiment  

SciTech Connect

CRESST-II, standing for Cryogenic Rare Events Search with Superconducting Thermometers phase II, is an experiment searching for Dark Matter. In the LNGS facility in Gran Sasso, Italy, a cryogenic detector setup is operated in order to detect WIMPs by elastic scattering off nuclei, generating phononic lattice excitations and scintillation light. The thermometers used in the experiment consist of a tungsten thin-film structure evaporated onto the CaWO{sub 4} absorber crystal. The process of evaporation causes a decrease in the scintillation light output. This, together with the need of a big-scale detector production for the upcoming EURECA experiment lead to investigations for producing thermometers on smaller crystals which are glued onto the absorber crystal. In our Run 31 we tested composite detectors for the first time in the Gran Sasso setup. They seem to produce higher light yields as hoped and could provide an additional time based discrimination mechanism for low light yield clamp events.

Kiefer, M.; Angloher, G.; Bavykina, I.; Hauff, D.; Huff, P.; Lang, R. F.; Pantic, E.; Petricca, F.; Proebst, F.; Schaeffner, K.; Schmaler, J.; Seidel, W.; Stodolsky, L. [Max-Planck-Institut fuer Physik, Foehringer Ring 6, D-80805 Muenchen (Germany); Bauer, M.; Deuter, G.; Jochum, J.; Kimmerle, M.; Rottler, K.; Sailer, C.; Scholl, S. [Eberhard-Karls-Universitaet Tuebingen, D-72076 Tuebingen (Germany)] (and others)

2009-12-16

312

Evaluation the nonlinear response function of a 3×3 in NaI scintillation detector for PGNAA applications  

Microsoft Academic Search

Response functions of the 3×3in NaI detector, which is mainly used in PGNAA applications, have been calculated by using MCNP-4C code. Calculated results are compared with measured data by using standard ?-ray sources and prompt ?-rays from pure element samples to check their accuracy. Prompt ?-rays from pure element samples were used for this determination in the range from 1.942

Hashem Miri Hakimabad; Hamed Panjeh; Alireza Vejdani-Noghreiyan

2007-01-01

313

Halide Scintillators  

Microsoft Academic Search

Scintillators have been used for decades to make ionising radiation visible. Either by direct observation of the light flash produced by the material when it is exposed to radiation, or indirect by use of a photomultiplier tube or photodiode.\\u000aDespite the enormous amount of commercially available scintillators, the ideal scintillator that combines a high light yield, a high density, a

E. V. D. Van Loef

2003-01-01

314

Scintillator material  

DOEpatents

An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography. 4 figs.

Anderson, D.F.; Kross, B.J.

1992-07-28

315

Scintillator material  

DOEpatents

An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography.

Anderson, David F. (Batavia, IL); Kross, Brian J. (Aurora, IL)

1992-01-01

316

Scintillator material  

DOEpatents

An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography.

Anderson, David F. (Batavia, IL); Kross, Brian J. (Aurora, IL)

1994-01-01

317

Scintillator material  

DOEpatents

An improved scintillator material comprising cerium fluoride is disclosed. Cerium fluoride has been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to known scintillator materials such as thallium-doped sodium iodide, barium fluoride and bismuth germanate. As a result, cerium fluoride is favorably suited for use as a scintillator material in positron emission tomography. 4 figs.

Anderson, D.F.; Kross, B.J.

1994-06-07

318

Separation and quantification of 238U, 232Th and rare earths in monazite samples by ion chromatography coupled with on-line flow scintillation detector.  

PubMed

An alternative procedure has been described for efficient separation and quantitative determination of uranium (U), thorium (Th) and rare earth elements (REEs) in monazite mineral by high performance ion chromatographic system (IC). Different variables affecting the distribution coefficient, the retention and hence separation efficiency such as eluent flow rate and concentrations of HCI and ammonium sulfate (NH4)2SO4 containing the mobile phase were studied. The developed separation protocol of U, Th and REEs was optimized using an Ion Pac CS5 separation column followed by post-column derivatization reaction with Arsenaso III and UV-VIS spectrophotometric detection. Comparative evaluation of U, Th and REEs concentration in monazite mineral was demonstrated using two different on-line detection modes including flow through cell scintillation detector (FSD) and UV-VIS spectrophotometer. Response of the FSD was found to be linear over the full range of activities investigated (4-100 Bq). The lower limits of detection (LLD) for the investigated radionuclides were 3.0+0.1 Bq for 238U and 6.0 +/- 0.1 Bq for 232Th. The detection of 238U and 232Th by FSD shows good agreement with the corresponding determination by UV-VIS spectrophotometer. The content of ThO2 and U3O8 in monazite sample were found to be 4.7 +/- 0.1% and 0.42 +/- 0.04% using UV-VIS detector and 4.3 +/- 0.1% and 0.45 +/- 0.1% using FSD, respectively. PMID:12361323

Borai, E H; Mady, A S

2002-10-01

319

A measurement of the response of an SCG1-C scintillation glass shower detector to 2 17.5 GeV positrons  

NASA Astrophysics Data System (ADS)

We have measured 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. We have measured the energy resolution of this 18.4 radiation length detector plus its attendant SF5 lead glass shower counter array to be ?/ E = (1.64±0.14)%+(1.13±0.33)%/? E with the constant term dominated by variations in the variations in the conversion point of the positron and shower leakage. We found this counter to be linear over the energy range examined. We have also measured the light output of the SCG1-C counter relative to light output of the SF5 lead glass guard blocks using 17.5 GeV positrons. We find that the SCG1-C counter produces 5.10±0.30 more light at the phototube than the SF5 lead glass counters.

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

1984-02-01

320

A measurement of the response of an SCG1-C scintillation glass shower detector to 2-17.5 GeV positrons  

NASA Astrophysics Data System (ADS)

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)% + (1.13 plus or minus 0.33)%/, square root of E with the constant term dominated by variations in the conversion point of the positron and shower leakage. This counter was found to be linear over the energy range examined. Also measured was the light output of the SCG1-C counter relative to light output of the SF5 lead glass guard blocks using 17.5 GeV positrons. It was found that the sOG1-C counter produces 5.10 plus or minus 0.30 more light at the phototube than the SF5 lead glass counters.

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

1983-04-01

321

Method of making a scintillator waveguide  

DOEpatents

The present invention is an apparatus for detecting ionizing radiation, having: a waveguide having a first end and a second end, the waveguide formed of a scintillator material wherein the therapeutic ionizing radiation isotropically generates scintillation light signals within the waveguide. This apparatus provides a measure of radiation dose. The apparatus may be modified to permit making a measure of location of radiation dose. Specifically, the scintillation material is segmented into a plurality of segments; and a connecting cable for each of the plurality of segments is used for conducting scintillation signals to a scintillation detector.

Bliss, Mary (West Richland, WA); Craig, Richard A. (West Richland, WA); Reeder, Paul L. (Richland, WA)

2000-01-01

322

A comparative study of small field total scatter factors and dose profiles using plastic scintillation detectors and other stereotactic dosimeters: The case of the CyberKnife  

SciTech Connect

Purpose: Small-field dosimetry is challenging, and the main limitations of most dosimeters are insufficient spatial resolution, water nonequivalence, and energy dependence. The purpose of this study was to compare plastic scintillation detectors (PSDs) to several commercial stereotactic dosimeters by measuring total scatter factors and dose profiles on a CyberKnife system. Methods: Two PSDs were developed, having sensitive volumes of 0.196 and 0.785 mm{sup 3}, and compared with other detectors. The spectral discrimination method was applied to subtract Cerenkov light from the signal. Both PSDs were compared to four commercial stereotactic dosimeters by measuring total scatter factors, namely, an IBA dosimetry stereotactic field diode (SFD), a PTW 60008 silicon diode, a PTW 60012 silicon diode, and a microLion. The measured total scatter factors were further compared with those of two independent Monte Carlo studies. For the dose profiles, two commercial detectors were used for the comparison, i.e., a PTW 60012 silicon diode and Gafchromics EBT2. Total scatter factors for a CyberKnife system were measured in circular fields with diameters from 5 to 60 mm. Dose profiles were measured for the 5- and 60-mm cones. The measurements were performed in a water tank at a 1.5-cm depth and an 80-cm source-axis distance. Results: The total scatter factors measured using all the detectors agreed within 1% with the Monte Carlo values for cones of 20 mm or greater in diameter. For cones of 10-20 mm in diameter, the PTW 60008 silicon diode was the only dosimeter whose measurements did not agree within 1% with the Monte Carlo values. For smaller fields (<10 mm), each dosimeter type showed different behaviors. The silicon diodes over-responded because of their water nonequivalence; the microLion and 1.0-mm PSD under-responded because of a volume-averaging effect; and the 0.5-mm PSD was the only detector within the uncertainties of the Monte Carlo simulations for all the cones. The PSDs, the PTW 60012 silicon diode, and the Gafchromics EBT2 agreed within 2% and 0.2 mm (gamma evaluation) for the measured dose profiles except in the tail of the 60-mm cone. Conclusions: Silicon diodes can be used to accurately measure small-field dose profiles but not to measure total scatter factors, whereas PSDs can be used to accurately measure both. The authors' measurements show that the use of a 1.0-mm PSD resulted in a negligible volume-averaging effect (under-response of Almost-Equal-To 1%) down to a field size of 5 mm. Therefore, PSDs are strong candidates to become reference radiosurgery detectors for beam characterization and quality assurance measurements.

Morin, J.; Beliveau-Nadeau, D.; Chung, E.; Seuntjens, J.; Theriault, D.; Archambault, L.; Beddar, S.; Beaulieu, L. [Departement de Physique, Universite Laval, Quebec (Canada)

2013-01-15

323

A phantom study of an in vivo dosimetry system using plastic scintillation detectors for real-time verification of 192Ir HDR brachytherapy  

PubMed Central

Purpose: The goal of the present work was to evaluate the accuracy of a plastic scintillation detector (PSD) system to perform in-phantom dosimetry during 192Ir high dose rate (HDR) brachytherapy treatments. Methods: A PSD system capable of stem effect removal was built. A red–green–blue photodiode connected to a dual-channel electrometer was used to detect the scintillation light emitted from a green scintillation component and transmitted along a plastic optical fiber. A clinically relevant prostate treatment plan was built using the HDR brachytherapy treatment planning system. An in-house fabricated template was used for accurate positioning of the catheters, and treatment delivery was performed in a water phantom. Eleven catheters were inserted and used for dose delivery from 192Ir radioactive source, while two others were used to mimic dosimetry at the rectum wall and in the urethra using a PSD. The measured dose and dose rate data were compared to the expected values from the planning system. The importance of removing stem effects from in vivo dosimetry using a PSD during 192Ir HDR brachytherapy treatments was assessed. Applications for dwell position error detection and temporal verification of the treatment delivery were also investigated. Results: In-phantom dosimetry measurements of the treatment plan led to a ratio to the expected dose of 1.003?±?0.004 with the PSD at different positions in the urethra and 1.043?±?0.003 with the PSD inserted in the rectum. Verification for the urethra of dose delivered within each catheter and at specific dwell positions led to average measured to expected ratios of 1.015?±?0.019 and 1.014?±?0.020, respectively. These values at the rectum wall were 1.059?±?0.045 within each catheter and 1.025?±?0.028 for specific dwell positions. The ability to detect positioning errors of the source depended of the tolerance on the difference to the expected value. A 5-mm displacement of the source was detected by the PSD system from 78% to 100% of the time depending on the acceptable range value. The implementation of a stem effect removal technique was shown to be necessary, particularly when calculating doses at specific dwell positions, and allowed decreasing the number of false-error detections—the detection of an error when it should not be the case—from 19 to 1 for a 5% threshold out of 43 measurements. The use of the PSD system to perform temporal verification of elapsed time by the source in each catheter—generally on the order of minutes—was shown to be in agreement within a couple of seconds with the treatment plan. Conclusions: We showed that the PSD system used in this study, which was capable of stem effect removal, can perform accurate dosimetry during 192Ir HDR brachytherapy treatment in a water phantom. The system presented here shows some clear advantages over previously proposed dosimetry systems for HDR brachytherapy, and it has the potential for various online verifications of treatment delivery quality. PMID:21776789

Therriault-Proulx, Francois; Briere, Tina M.; Mourtada, Firas; Aubin, Sylviane; Beddar, Sam; Beaulieu, Luc

2011-01-01

324

Reconstruction algorithm for point source neutron imaging through finite thickness scintillator  

NASA Astrophysics Data System (ADS)

A new inversion algorithm based on the maximum entropy method (MEM) is proposed to remove unwanted effects in fast neutron imaging which result from an uncollimated source interacting with a finitely thick scintillator. The algorithm takes as an input the image from the thick scintillator (TS) and the radiography setup geometry. The algorithm then outputs a restored image which appears as if taken with an infinitesimally thin scintillator (ITS). The inversion is accomplished by numerically generating a probabilistic model relating the ITS image to the TS image and then inverting this model on the TS image through MEM. Algorithm details as well as numerical results using MCNP simulated images are presented. This reconstruction technique can reduce the exposure time or the required source intensity without undesirable object blurring on the image by allowing the use of both thicker scintillators with higher efficiencies and closer source-to-detector distances to maximize incident radiation flux. The technique should also be applicable to high energy gamma or x-ray radiography using thick scintillators.

Wang, H.; Tang, V.; McCarrick, J.; Moran, S.

2012-11-01

325

Liquid xenon scintillation spectrometer  

NASA Astrophysics Data System (ADS)

A liquid xenon scintillation detector has been worked out. Liquid xenon fills up a volume 27 mm diameter by 12-30 mm long inside a quartz cylinder with a teflon reflector. Both ends of the cylinder are sealed with photomultipliers with quartz windows. The energy resolution of the detector was found to be of the same order of magnitude as NaI(Tl) crystals for the energy 120 KeV. However, the resolution increases for the higher energies and comes up to 15% for 662 KeV. The reasons of such deterioration of resolution with increasing energy are discussed.

Barabanov, I. R.; Gavrin, V. N.; Pshukov, A. M.

1987-02-01

326

Low-cost extruded plastic scintillator  

NASA Astrophysics Data System (ADS)

Motivated by a need for lower cost plastic scintillation detectors, we have tested commercially available polystyrene pellets in order to produce scintillating materials that can be extruded into various shapes. Selection of the raw materials is discussed. Two techniques are described that add wavelength shifting dopants to polystyrene pellets and extrude plastic scintillating bars using these materials. Data on light yield and transmittance are presented.

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

2001-07-01

327

LORA: A scintillator array for LOFAR to measure extensive air showers  

E-print Network

The measurement of the radio emission from extensive air showers, induced by high-energy cosmic rays is one of the key science projects of the LOFAR radio telescope. The LOfar Radboud air shower Array (LORA) has been installed in the core of LOFAR in the Netherlands. The main purpose of LORA is to measure the properties of air showers and to trigger the read-out of the LOFAR radio antennas to register extensive air showers. The experimental set-up of the array of scintillation detectors and its performance are described.

S. Thoudam; S. Buitink; A. Corstanje; J. E. Enriquez; H. Falcke; W. Frieswijk; J. R. Hörandel; A. Horneffer; M. Krause; A. Nelles; P. Schellart; O. Scholten; S. ter Veen; M. van den Akker

2014-08-19

328

LORA: A scintillator array for LOFAR to measure extensive air showers  

E-print Network

The measurement of the radio emission from extensive air showers, induced by high-energy cosmic rays is one of the key science projects of the LOFAR radio telescope. The LOfar Radboud air shower Array (LORA) has been installed in the core of LOFAR in the Netherlands. The main purpose of LORA is to measure the properties of air showers and to trigger the read-out of the LOFAR radio antennas to register extensive air showers. The experimental set-up of the array of scintillation detectors and its performance are described.

Thoudam, S; Corstanje, A; Enriquez, J E; Falcke, H; Frieswijk, W; Hörandel, J R; Horneffer, A; Krause, M; Nelles, A; Schellart, P; Scholten, O; ter Veen, S; Akker, M van den

2014-01-01

329

LORA: A scintillator array for LOFAR to measure extensive air showers  

NASA Astrophysics Data System (ADS)

The measurement of the radio emission from extensive air showers, induced by high-energy cosmic rays, is one of the key science projects of the LOFAR radio telescope. The LOfar Radboud air shower Array (LORA) has been installed in the core of LOFAR in the Netherlands. The main purpose of LORA is to measure the properties of air showers and to trigger the read-out of the LOFAR radio antennas to register extensive air showers. The experimental set-up of the array of scintillation detectors and its performance are described.

Thoudam, S.; Buitink, S.; Corstanje, A.; Enriquez, J. E.; Falcke, H.; Frieswijk, W.; Hörandel, J. R.; Horneffer, A.; Krause, M.; Nelles, A.; Schellart, P.; Scholten, O.; ter Veen, S.; van den Akker, M.

2014-12-01

330

First results of the experiment to search for double beta decay of 106Cd with 106CdWO4 crystal scintillator in coincidence with four crystals HPGe detector  

E-print Network

An experiment to search for double beta processes in 106Cd by using cadmium tungstate crystal scintillator enriched in 106Cd (106CdWO4) in coincidence with the four crystals HPGe detector GeMulti is in progress at the STELLA facility of the Gran Sasso underground laboratory of INFN (Italy). The 106CdWO4 scintillator is viewed by a low-background photomultiplier tube through a lead tungstate crystal light-guide produced from deeply purified archaeological lead to suppress gamma quanta from the photomultiplier tube. Here we report the first results of the experiment after 3233 hours of the data taking. A few new improved limits on double beta processes in 106Cd are obtained, in particular T1/2(2nuECb+) > 8.4e20 yr at 90% C.L.

V. I. Tretyak; P. Belli; R. Bernabei; V. B. Brudanin; F. Cappella; V. Caracciolo; R. Cerulli; D. M. Chernyak; F. A. Danevich; S. d'Angelo; A. Incicchitti; M. Laubenstein; V. M. Mokina; D. V. Poda; O. G. Polischuk; R. B. Podviyanuk; I. A. Tupitsyna

2013-12-19

331

AMoRE: Collaboration for searches for the neutrinoless double-beta decay of the isotope of {sup 100}Mo with the aid of {sup 40}Ca{sup 100}MoO{sub 4} as a cryogenic scintillation detector  

SciTech Connect

The AMoRE (Advanced Mo based Rare process Experiment) Collaboration is planning to employ {sup 40}Ca{sup 100}MoO{sub 4} single crystals as a cryogenic Scintillation detector for studying the neutrinoless double-beta decay of the isotope {sup 100}Mo. A simultaneous readout of phonon and scintillation signals is performed in order to suppress the intrinsic background. The planned sensitivity of the experiment that would employ 100 kg of {sup 40}Ca{sup 100}MoO{sub 4} over five years of data accumulation would be T{sub 1/2}{sup 0{nu}} = 3 Multiplication-Sign 10{sup 26} yr, which corresponds to values of the effective Majorana neutrino mass in the range of Left-Pointing-Angle-Bracket m{sub {nu}} Right-Pointing-Angle-Bracket {approx} 0.02-0.06 eV.

Khanbekov, N. D., E-mail: xanbekov@gmail.com [Institute of Theoretical and Experimental Physics (Russian Federation)

2013-09-15

332

Detectors  

DOEpatents

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

Orr, Christopher Henry (Calderbridge, GB); Luff, Craig Janson (Calderbridge, GB); Dockray, Thomas (Calderbridge, GB); Macarthur, Duncan Whittemore (Los Alamos, NM); Bounds, John Alan (Los Alamos, NM); Allander, Krag (Los Alamos, NM)

2002-01-01

333

Use of Silicon Photomultipliers in ZnS:6LiF scintillation neutron detectors: signal extraction in presence of high dark count rates  

NASA Astrophysics Data System (ADS)

We report on the possibility of using Silicon Photomultipliers (SiPMs) to detect the scintillation light from neutron conversion in ZnS:6LiF scintillators. The light is collected by wavelength-shifting fibers embedded into the scintillator. The difficulty of extracting neutron signals in the presence of high dark count rates of the SiPMs is addressed by applying a dedicated processing algorithm to analyze the temporal distribution of the SiPM pulses. With a single-channel prototype detection unit we demonstrate a very good neutron signal extraction at SiPM dark count rates of about 1 MHz.

Stoykov, A.; Mosset, J.-B.; Greuter, U.; Hildebrandt, M.; Schlumpf, N.

2014-06-01

334

The Time Structure of Hadronic Showers in Calorimeters with Scintillator and with Gas Readout  

NASA Astrophysics Data System (ADS)

The time structure of hadronic showers is characterized by a prompt component from relativistic particles and by late components predominantly connected to neutrons in the cascade. The sensitivity to this late component thus depends on the choice of the active medium for hadronic calorimeters. The time structure and the differences originating from different readout technologies in a calorimeter with tungsten absorbers are studied with two dedicated setups using scintillator tiles read out with SiPMs and glass RPCs. In both cases, a radial strip of 15 cells with a size of 3 × 3 cm2 each is read out with fast digitizers with deep buffers, providing detailed information on the time structure of the recorded signals over a long sampling window. We will discuss the technical aspects of these systems, and present results on the time structure measurements, which demonstrate sizeable differences in the response of scintillator and gaseous detectors to the neutron components of the hadronic cascade.

Szalay, Marco

2014-06-01

335

A high resolution scintillating fiber tracker with SiPM readout  

NASA Astrophysics Data System (ADS)

A novel modular high-resolution charged-particle tracking detector design using 250 ?m diameter, round, scintillating fibers and SiPM arrays for readout is presented. The fiber modules consist of eight layers of 128 fibers, mechanically stabilized by a carbon fiber/Rohacell foam structure. A prototype using scintillating fibers with a diameter of 300 ?m and two types of silicon photomultipliers has been tested in a 10 GeV proton beam in late October 2006 at the T9 PS-beamline, CERN. We present the measured spatial resolution, efficiency and signal-over-noise for this setup. The advantage of this tracker concept is a compact and modular design with low material budget and only little or no cooling requirements depending on the quality of the silicon photomultiplieres.

Gast, Henning; Kirn, Thomas; Roper Yearwood, Gregorio; Schael, Stefan

2007-10-01

336

500 MHz neutron detector  

SciTech Connect

A {sup 10}B-loaded scintillation detector was built for neutron transmission measurements at the Los Alamos Neutron Scattering Center. The efficiency of the detector is nearly 100% for neutron energies from 0 to 1 keV. The neutron moderation time in the scintillator is about 250 ns and is energy independent. The detector and data processing system are designed to handle an instantaneous rate as high as 500 MHz. The active area of the detector is 40 cm in diameter.

Yen, Yi-Fen; Bowman, J.D. [Los Alamos National Lab., NM (United States); Matsuda, Y. [Kyoto Univ. (Japan). Dept. of Physics

1993-12-01

337

Scintillating Stars  

NSDL National Science Digital Library

Often, a bright planet that is visible over the horizon will be mistaken for a star. Some believe they can tell the difference between a star and a planet because stars twinkle, or scintillate , and planets do not. In actuality however, both will twinkle because any light that passes through our atmosphere, whether it be reflected from a planet or generated by a star, will be interfered with by the atmospheric elements. This month's column sheds light on this "scintillating" subject and engages students in a research activity that revolves around the question: Is Pluto a planet?

Riddle, Bob

2003-02-01

338

Optics: general-purpose scintillator light response simulation code  

E-print Network

We present the program optics that simulates the light response of an arbitrarily shaped scintillation particle detector. Predicted light responses of pure CsI polygonal detectors, plastic scintillator staves, cylindrical plastic target scintillators and a Plexiglas light-distribution plate are illustrated. We demonstrate how different bulk and surface optical properties of a scintillator lead to specific volume and temporal light collection probability distributions. High-statistics optics simulations are calibrated against the detector responses measured in a custom-made cosmic muon tomography apparatus. The presented code can also be used to track particles intersecting complex geometrical objects.

E. Frlez; B. K. Wright; D. Pocanic

2000-06-27

339

Setup in the surfzone  

E-print Network

Surfzone wave height transformation and wave-breaking-driven increases in the mean sea level (setup) are examined on alongshore-uniform beaches with alongshore homogeneous and inhomogeneous wave forcing. While previously ...

Apotsos, Alex

2007-01-01

340

Use of Silicon Photomultipliers in ZnS:6LiF scintillation neutron detectors: signal extraction in presence of high dark count rates  

E-print Network

We report on the possibility of using Silicon Photomultipliers (SiPMs) to detect the scintillation light from neutron conversion in ZnS:6LiF scintillators. The light is collected by wavelength-shifting fibers and adapted to the sensitivity range of the SiPMs. The difficulty of extracting neutron signals in presence of high dark count rates of the SiPMs is addressed by applying a dedicated processing algorithm to analyze the temporal distribution of the SiPM pulses. With a single-channel prototype detection unit we demonstrate a very good neutron signal extraction at SiPM dark count rates of about 1 MHz.

Stoykov, A; Greuter, U; Hildebrandt, M; Schlumpf, N

2014-01-01

341

Scintillator Cosmic Ray Super Telescope  

NASA Astrophysics Data System (ADS)

The Scintillator Cosmic Ray Super Telescope (SciCRST) is a new experiment to detect solar neutrons, and also it is expected to work as a muon and cosmic ray detector. The SciCRST consist of 14,848 plastic scintillator bars, and it will be installed at the top of Sierra Negra volcano, Mexico, 4580 m.a.s.l. We use a prototype, called as miniSciBar, to test the hardware and software of the final experiment. In this paper, we present the status and details of the experiment, and results of the prototype.

González, L. X.; Valdés-Galicia, J. F.; Matsubara, Y.; Nagai, Y.; Itow, Y.; Sako, T.; López, D.; Mitsuka, G.; Munakata, K.; Kato, C.; Yasue, S.; Kosai, M.; Tsurusashi, M.; Nakamo, Y.; Shibata, S.; Takamaru, H.; Kojima, H.; Tsuchiya, H.; Watanabe, K.; Koi, T.; Fragoso, E.; Hurtado, A.; Musalem, O.

2013-04-01

342

The homestake surface-underground scintillations: Description  

Microsoft Academic Search

Two new detectors are currently under construction at the Homestake Gold Mine. Underground, the Large Area Scintillation Detector will be used to (1) search for slow, massive magnetic monopoles; (2) study the zenith angle distribution of neutrino-induced and penetrating muons; (3) search for neutrino bursts from stellar collapse events in the Galaxy; and (4) serve as a prototype for a

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

1985-01-01

343

Indirect flat-panel detector with avalanche gain: Fundamental feasibility investigation for SHARP-AMFPI (scintillator HARP active matrix flat panel imager)  

Microsoft Academic Search

An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The final electronic image is read out using an active matrix array of thin film transistors (TFT). We call the proposed

Wei Zhao; Li Dan; Alla Reznik; B. J. M. Lui; D. C. Hunt; J. A. Rowlands; Yuji Ohkawa; Kenkichi Tanioka

2005-01-01

344

Optimization of light collection from crystal scintillators for cryogenic experiments  

E-print Network

High light collection efficiency is an important requirement in any application of scintillation detectors. The purpose of this study is to investigate the possibility for improving this parameter in cryogenic scintillation bolometers, which can be considered as a promising detectors in experiments investigating neutrinoless double beta decay and dark matter. Energy resolutions and relative pulse amplitudes of scintillation detectors using ZnWO4 scintillation crystals of different shapes (cylinder 20 mm in dimater by 20 mm and hexagonal prism with diagonal 20 mm and height 20 mm), reflector materials and shapes, optical contact and surface properties (polished and diffused) were measured at room temperature. Propagation of optical photons in these experimental conditions was simulated using Geant4 and ZEMAX codes. The results of the simulations are found to be in good agreement with each other and with direct measurements of the crystals. This could be applied to optimize the geometry of scintillation detectors used in the cryogenic experiments.

F. A. Danevich; R. V. Kobychev; V. V. Kobychev; H. Kraus; V. B. Mikhailik; V. M. Mokina

2014-02-10

345

Extruded scintillator for the Calorimetry applications  

SciTech Connect

An extrusion line has been installed and successfully operated at FNAL (Fermi National Accelerator Laboratory) in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new Facility will serve to further develop and improve extruded plastic scintillator. Recently progress has been made in producing co-extruded plastic scintillator, thus increasing the potential HEP applications of this Facility. The current R and D work with extruded and co-extruded plastic scintillator for a potential ALICE upgrade, the ILC calorimetry program and the MINERvA experiment show the attractiveness of the chosen strategy for future experiments and calorimetry. We extensively discuss extruded and co-extruded plastic scintillator in calorimetry in synergy with new Solid State Photomultipliers. The characteristics of extruded and co-extruded plastic scintillator will be presented here as well as results with non-traditional photo read-out.

Dyshkant, A.; Rykalin, V.; Pla-Dalmau, A.; Beznosko, D. [Northern Illinois Center for Accelerator and Detector Development (NICADD), Northern Illinois University, DeKalb, IL 60115 (United States); Fermi Nationa Acceleratorl Laboratory, Batavia, IL 60510 (United States); State University of New York at Stony Brook, Stony Brook, NY 11790 (United States)

2006-10-27

346

SNO+ Scintillator Purification and Assay  

NASA Astrophysics Data System (ADS)

We describe the R&D on the scintillator purification and assay methods and technology for the SNO+ neutrino and double-beta decay experiment. The SNO+ experiment is a replacement of the SNO heavy water with liquid scintillator comprised of 2 g/L PPO in linear alkylbenzene (LAB). During filling the LAB will be transported underground by rail car and purified by multi-stage distillation and steam stripping at a flow rate of 19 LPM. While the detector is operational the scintillator can be recirculated at 150 LPM (full detector volume in 4 days) to provide repurification as necessary by either water extraction (for Ra, K, Bi) or by functional metal scavenger columns (for Pb, Ra, Bi, Ac, Th) followed by steam stripping to remove noble gases and oxygen (Rn, O2, Kr, Ar). The metal scavenger columns also provide a method for scintillator assay for ex-situ measurement of the U and Th chain radioactivity. We have developed "natural" radioactive spikes of Pb and Ra in LAB and use these for purification testing. Lastly, we present the planned operating modes and purification strategies and the plant specifications and design.

Ford, R.; Chen, M.; Chkvorets, O.; Hallman, D.; Vázquez-Jáuregui, E.

2011-04-01

347

SNO+ Scintillator Purification and Assay  

SciTech Connect

We describe the R and D on the scintillator purification and assay methods and technology for the SNO+ neutrino and double-beta decay experiment. The SNO+ experiment is a replacement of the SNO heavy water with liquid scintillator comprised of 2 g/L PPO in linear alkylbenzene (LAB). During filling the LAB will be transported underground by rail car and purified by multi-stage distillation and steam stripping at a flow rate of 19 LPM. While the detector is operational the scintillator can be recirculated at 150 LPM (full detector volume in 4 days) to provide repurification as necessary by either water extraction (for Ra, K, Bi) or by functional metal scavenger columns (for Pb, Ra, Bi, Ac, Th) followed by steam stripping to remove noble gases and oxygen (Rn, O{sub 2}, Kr, Ar). The metal scavenger columns also provide a method for scintillator assay for ex-situ measurement of the U and Th chain radioactivity. We have developed ''natural'' radioactive spikes of Pb and Ra in LAB and use these for purification testing. Lastly, we present the planned operating modes and purification strategies and the plant specifications and design.

Ford, R.; Vazquez-Jauregui, E. [SNOLAB, Creighton Mine, Lively, P3Y 1N2 (Canada); Chen, M. [Department of Physics, Queen's University, Kingston, K7L 3N6 (Canada); Chkvorets, O.; Hallman, D. [Department of Physics, Laurentian University, Sudbury, P3E 2C6 (Canada)

2011-04-27

348

Inorganic scintillators in direct dark matter investigation  

NASA Astrophysics Data System (ADS)

The discoveries, the developments and the studies that have been performed in the research of new materials and purification techniques, nowadays allow us a wide choice among inorganic scintillators for a variety of uses. In this paper the application of the inorganic crystal scintillators to direct dark matter investigation will be considered in more detail. The present framework of the detectors used at low energy for direct dark matter investigation also offers useful hints for further corollary developments.

Belli, P.; Incicchitti, A.; Cappella, F.

2014-07-01

349

CARMA Correlator Graphical Setup  

Microsoft Academic Search

CARMA Correlator Graphical Setup (CGS) is a Java tool to help users of the Combined Array for Research in Millimeter-wave Astronomy (CARMA) plan observations. It allows users to visualize the correlator bands overlaid on frequency space and view spectral lines within each band. Bands can be click-dragged to anywhere in frequency and can have their properties (e.g., bandwidth, quantization level,

D. We; B. Shaya; M. W. Pound

2011-01-01

350

Automated Calibration Procedures for an Array of Position-resolving NaI-Detectors  

NASA Astrophysics Data System (ADS)

Recently, a new experimental setup called uc(stripsi) was constructed at Florida State University's superconducting accelerator laboratory. It consists of two annular, double--sided Silicon strip detectors and an array of 24 position--resolving NaI(Tl) scintillation detectors. In a first experiment performed in July 2002, the setup was used to detect ???? coincidence events from the ^12C(^16O,?) ^24Mg reaction, with the aim of measuring the quadruple angular correlations and, thus, determine spins of high-lying states in ^24Mg. In this experiment, the 24 NaI-- detectors measure both energies and positions of the ?--rays emitted from the nuclear reaction. In order to accomplish that, each detector possesses two photomultiplier tubes attached to the opposite ends of a cylindrical crystal. Since the scintillation light is attenuated as it travels through the crystal, the relative light output on both sides can be used to reconstruct the position of the ? ray along the cylinder axis. This presentation focuses on the calibration and data analysis methods employed in the analysis of signals from these detectors. We tested two different hypotheses in the reconstruction of ?--ray energy and position. The first method assumes exponential light attenuation, the second a linear attenuation. We will compare the merits of both approaches. We developed software tools to automatically determine compensation for electronic gain drifts which occurred during the experiment.

Lee, Yik-Kheng; Diffenderfer, Eric; Fridmann, Joel; Wiedenhoever, Ingo

2002-10-01

351

CARMA Correlator Graphical Setup  

NASA Astrophysics Data System (ADS)

CARMA Correlator Graphical Setup (CGS) is a Java tool to help users of the Combined Array for Research in Millimeter-wave Astronomy (CARMA) plan observations. It allows users to visualize the correlator bands overlaid on frequency space and view spectral lines within each band. Bands can be click-dragged to anywhere in frequency and can have their properties (e.g., bandwidth, quantization level, rest frequency) changed interactively. Spectral lines can be filtered from the view by expected line strength to reduce visual clutter. Once the user is happy with the setup, a button click generates the Python commands needed to configure the correlator within the observing script. CGS can also read Python configurations from an observing script and reproduce the correlator setup that was used. Because the correlator hardware description is defined in an XML file, the tool can be rapidly reconfigured for changing hardware. This has been quite useful as CARMA has recently commissioned a new correlator. The tool was written in Java by high school summer interns working in UMD's Laboratory for Millimeter Astronomy and has become an essential planning tool for CARMA PIs.

Wu, D.; Shaya, B.; Pound, M. W.

2011-07-01

352

HERACLES-II setup at TRIUMF  

NASA Astrophysics Data System (ADS)

The HERACLES-II multidetector is an array composed of several types of detectors and is used to study heavy ion reactions at intermediate energies. The original version was designed to detect fragments produced by collisions between 20 and 100 A MeV. In order to use the radioactive beams accelerated by ISAC-II (Eproj?15 A MeV), the matrix was moved to TRIUMF and underwent an overhaul. The detector thresholds were lowered and the first rings (low angle) were replaced. Tests at 9.2 A MeV allowed us to evaluate the efficiency of the new setup at low beam energy.

Gauthier, J.; Roy, R.; Wallace, B.; St-Onge, P.; Frégeau, M. O.; Gagnon-Moisan, F.; Boisjoli, M.; St-Pierre, C.

2013-07-01

353

Detecting scintillations in liquid helium  

NASA Astrophysics Data System (ADS)

We review our work in developing a tetraphenyl butadiene (TPB)-based detection system for a measurement of the neutron lifetime using magnetically confined ultracold neutrons (UCN). As part of the development of the detection system for this experiment, we studied the scintillation properties of liquid helium itself, characterized the fluorescent efficiencies of different fluors, and built and tested three detector geometries. We provide an overview of the results from these studies as well as references for additional information.

Huffman, P. R.; McKinsey, D. N.

2013-09-01

354

An LED, Fiber-Optic, Gain Monitoring System for a Segmented Scintillator Array  

E-print Network

with a segmented, liquid scintillator neutron detector array. The system is designed to track neutron detector cell of tracking the gains of individual detector cells to the design accuracy of 3%. Key words: Scintillator, Gain Intensity Gamma Source (HIGS) at the Duke University Free-Electron Laser Facility to make precision

Saskatchewan, University of

355

Gamma ray detector shield  

DOEpatents

A gamma ray detector shield comprised of a rigid, lead, cylindrical-shaped vessel having upper and lower portions with an pneumatically driven, sliding top assembly. Disposed inside the lead shield is a gamma ray scintillation crystal detector. Access to the gamma detector is through the sliding top assembly.

Ohlinger, R.D.; Humphrey, H.W.

1985-08-26

356

Calibration of Small Plastic Scintillators for Imaging Applications  

SciTech Connect

This report presents the results of measurements and simulations performed with 12 small plastic scintillation detectors manufactured by Scionix for imaging applications. The scintillator is equivalent to a Bicron BC-420 plastic scintillator. A gamma calibration is presented to determine the voltage to be applied on each detector to ensure uniform detector operation. Time of flight measurements performed with a Cf-252 source are also presented. Comparisons between experimental data and data from the Monte Carlo simulations show good agreement for time lags of 0 to 70 ns.

Pozzi, S.

2005-01-19

357

Optimization of light collection from crystal scintillators for cryogenic experiments  

E-print Network

High light collection efficiency is an important requirement in any application of scintillation detectors. The purpose of this study is to investigate the possibility for improving this parameter in cryogenic scintillation bolometers, which can be considered as a promising detectors in experiments investigating neutrinoless double beta decay and dark matter. Energy resolutions and relative pulse amplitudes of scintillation detectors using ZnWO4 scintillation crystals of different shapes (cylinder 20 mm in dimater by 20 mm and hexagonal prism with diagonal 20 mm and height 20 mm), reflector materials and shapes, optical contact and surface properties (polished and diffused) were measured at room temperature. Propagation of optical photons in these experimental conditions was simulated using Geant4 and ZEMAX codes. The results of the simulations are found to be in good agreement with each other and with direct measurements of the crystals. This could be applied to optimize the geometry of scintillation detecto...

Danevich, F A; Kobychev, V V; Kraus, H; Mikhailik, V B; Mokina, V M

2014-01-01

358

Energy resolution of gamma-ray spectroscopy of JET plasmas with a LaBr{sub 3} scintillator detector and digital data acquisition  

SciTech Connect

A new high efficiency, high resolution, fast {gamma}-ray spectrometer was recently installed at the JET tokamak. The spectrometer is based on a LaBr{sub 3}(Ce) scintillator coupled to a photomultiplier tube. A digital data acquisition system is used to allow spectrometry with event rates in excess of 1 MHz expected in future JET DT plasmas. However, at the lower rates typical of present day experiments, digitization can degrade the energy resolution of the system, depending on the algorithms used for extracting pulse height information from the digitized pulses. In this paper, the digital and analog spectrometry methods were compared for different experimental conditions. An algorithm based on pulse shape fitting was developed, providing energy resolution equivalent to the traditional analog spectrometry method.

Nocente, M.; Tardocchi, M.; Grosso, G.; Perelli Cippo, E.; Pietropaolo, A.; Proverbio, I.; Gorini, G. [Dipartimento di Fisica, Universita degli Studi di Milano-Bicocca and Istituto di Fisica del Plasma, Associazione EURATOM-ENEA-CNR, 20125 Milano (Italy); Chugunov, I.; Gin, D.; Shevelev, A. [A. F. Ioffe Physico-Technical Institute, St. Petersburg 194021 (Russian Federation); Pereira, R. C.; Fernandes, A. M.; Neto, A.; Sousa, J. [Associacao EURATOM/IST Centro de Fusao Nuclear, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal); Edlington, T.; Kiptily, V.; Syme, B. [Culham Centre for Fusion Energy, Culham OX143DB (United Kingdom); Murari, A. [Consorzio RFX, 35127 Padova (Italy); Collaboration: JET-EFDA Contributors

2010-10-15

359

Detection of high frequency intensity oscillations at RESEDA using the CASCADE detector  

NASA Astrophysics Data System (ADS)

We have explored the technological potential of combining neutron resonance spin echo (NRSE) with the time-of-flight method in quasielastic neutron scattering (QENS) experiments. For these test measurements at the new NRSE instrument RESEDA (FRM II, Munich), we have employed CASCADE, one of the fastest neutron detectors in the world, developed at the University of Heidelberg. Conventionally, scintillation detectors are used, in order to detect neutron intensities with high time resolution. In contrast, we used the new CASCADE detector converting neutrons in thin 10B layers being capable of resolving neutron intensity modulations up to the megahertz regime. This fast detector allows us to abandon the last resonance flip coil of a standard NRSE setup. The classical spin echo signal is replaced by a time-modulated signal. In this setup, fast intensity modulations are present at the detector position. In order to demonstrate, that NRSE-CASCADE operates well up to detector frequencies of 10 MHz, we performed elastic polarization test measurements on a standard sample. The CASCADE detector is a multidetector accumulating counts in 128 × 128 pixels on a surface of 200 mm × 200 mm. We have analyzed the signal in 600 pixels, providing information about the spin phase reaching the detector and about the resolution function of this new variant tested at RESEDA.

Häussler, W.; Böni, P.; Klein, M.; Schmidt, C. J.; Schmidt, U.; Groitl, F.; Kindervater, J.

2011-04-01

360

Gamma spectrometry and plastic-scintillator inherent background  

Microsoft Academic Search

The authors measured the energy resolution for a linear dependence of light yield on gamma radiation energy of gamma spectrometers based on plastic scintillation detectors for several plastic scintillators. If there were several gamma lines from the source the line with the highest energy was used to eliminate distortion due to overlap from the Compton background from gamma radiation of

V. V. Pomerantsev; I. B. Gagauz; L. I. Mitsai; V. S. Pilipenko; V. M. Solomonov; V. V. Chernikov; Y. A. Tsirlin

1988-01-01

361

Some studies of avalanche photodiode readout of fast scintillators  

SciTech Connect

Photomultipliers (PMs) are the classical readout element for scintillation detectors in high energy particle physics, nuclear physics, medical physics, industrial radiation monitors etc. Here, large area avalanche photodiodes with high performance, narrow operation tolerances and high reliability have recently become available. The authors report on some tests of their performance in the readout of fast scintillators.

Holl, I.; Lorenz, E. [Max-Planck-Inst. fuer Physik, Muenchen (Germany)] [Max-Planck-Inst. fuer Physik, Muenchen (Germany); Natkaniez, S. [Inst. of Nuclear Physics, Krakow (Poland)] [Inst. of Nuclear Physics, Krakow (Poland); Renker, D. [Paul Scherrer Inst., Villigen (Switzerland)] [Paul Scherrer Inst., Villigen (Switzerland); Schmelz, C. [Max-Planck-Inst. fuer Physik, Muenchen (Germany)] [Max-Planck-Inst. fuer Physik, Muenchen (Germany); [Technische Univ. Muenchen (Germany). Nuklearmedizinische Klinik Rechts der Isar; Schwartz, B. [Budger Institute of Nuclear Physics, Novosibirsk (Russian Federation)] [Budger Institute of Nuclear Physics, Novosibirsk (Russian Federation)

1995-08-01

362

The COMPASS Setup for Physics with Hadron Beams  

E-print Network

The main characteristics of the COMPASS experimental setup for physics with hadron beams are described. This setup was designed to perform exclusive measurements of processes with several charged and/or neutral particles in the final state. Making use of a large part of the apparatus that was previously built for spin structure studies with a muon beam, it also features a new target system as well as new or upgraded detectors. The hadron setup is able to operate at the high incident hadron flux available at CERN. It is characterised by large angular and momentum coverages, large and nearly flat acceptances, and good two and three-particle mass resolutions. In 2008 and 2009 it was successfully used with positive and negative hadron beams and with liquid hydrogen and solid nuclear targets. This article describes the new and upgraded detectors and auxiliary equipment, outlines the reconstruction procedures used, and summarises the general performance of the setup.

Abbon, Ph.; The COMPASS collaboration; Akhunzyanov, R.; Alexandrov, Yu.; Alexeev, M.G.; Alexeev, G.D.; Amoroso, A.; Andrieux, V.; Anosov, V.; Austregesilo, A.; Badelek, B.; Balestra, F.; Barth, J.; Baum, G.; Beck, R.; Bedfer, Y.; Berlin, A.; Bernhard, J.; Bicker, K.; Bielert, E.R.; Bieling, J.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Buechele, M.; Burtin, E.; Capozza, L.; Ciliberti, P.; Chiosso, M.; Chung, S.U.; Cicuttin, A.; Colantoni, M.; Cotte, D.; Crespo, M.L.; Curiel, Q.; Dafni, T.; Dalla Torre, S.; Dasgupta, S.S.; Dasgupta, S.; Denisov, O.Yu.; Desforge, D.; Dinkelbach, A.M.; Donskov, S.V.; Doshita, N.; Duic, V.; Duennweber, W.; Durand, D.; Dziewiecki, M.; Efremov, A.; Elia, C.; Eversheim, P.D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Finger, M.; Finger jr., M.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J.M.; Frolov, V.; Gatignon, L.; Gautheron, F.; Gavrichtchouk, O.P.; Gerassimov, S.; Geyer, R.; Giganon, A.; Gnesi, I.; Gobbo, B.; Goertz, S.; Gorzellik, M.; Grabmueller, S.; Grasso, A.; Gregori, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; von Harrach, D.; Hahne, D.; Hashimoto, R.; Heinsius, F.H.; Herrmann, F.; Hinterberger, F.; Hoeppner, Ch.; Horikawa, N.; d'Hose, N.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Jasinski, P.; Joerg, P.; Joosten, R.; Kabuss, E.; Ketzer, B.; Khaustov, G.V.; Khokhlov, Yu.A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J.H.; Kolosov, V.N.; Kondo, K.; Koenigsmann, K.; Konorov, I.; Konstantinov, V.F.; Kotzinian, A.M.; Kouznetsov, O.; Kraemer, M.; Kroumchtein, Z.V.; Kuchinski, N.; Kuhn, R.; Kunne, F.; Kurek, K.; Kurjata, R.P.; Lednev, A.A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lichtenstadt, J.; Maggiora, A.; Magnon, A.; Makke, N.; Mallot, G.K.; Marchand, C.; Marroncle, J.; Martin, A.; Marzec, J.; Matousek, J.; Matsuda, H.; Matsuda, T.; Menon, G.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Yu.V.; Miyachi, Y.; Moinester, M.A.; Nagaytsev, A.; Nagel, T.; Nerling, F.; Neubert, S.; Neyret, D.; Nikolaenko, V.I.; Novy, J.; Nowak, W.-D.; Nunes, A.S.; Olshevsky, A.G.; Orlov, I.; Ostrick, M.; Panknin, R.; Panzieri, D.; Parsamyan, B.; Paul, S.; Pesaro, G.; Pesaro, V.; Peshekhonov, D.V.; Pires, C.; Platchkov, S.; Pochodzalla, J.; Polyakov, V.A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Reymond, J-M.; Rocco, E.; Rossiyskaya, N.S.; Rousse, J.-Y.; Ryabchikov, D.I.; Rychter, A.; Samartsev, A.; Samoylenko, V.D.; Sandacz, A.; Sarkar, S.; Savin, I.A.; Sbrizzai, G.; Schiavon, P.; Schill, C.; Schlueter, T.; Schmidt, K.; Schmieden, H.; Schoenning, K.; Schopferer, S.; Schott, M.; Shevchenko, O.Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Sosio, S.; Sozzi, F.; Srnka, A.; Steiger, L.; Stolarski, M.; Sulc, M.; Sulej, R.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; ter Wolbeek, J.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Tskhay, V.; Uhl, S.; Uman, I.; Virius, M.; Wang, L.; Weisrock, T.; Weitzel, Q.; Wilfert, M.; Windmolders, R.; Wollny, H.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zink, A.

2014-01-01

363

Scintillator efficiency study with MeV x-rays  

NASA Astrophysics Data System (ADS)

We have investigated scintillator efficiency for MeV radiographic imaging. This paper discusses the modeled detection efficiency and measured brightness of a number of scintillator materials. An optical imaging camera records images of scintillator emission excited by a pulsed x-ray machine. The efficiency of various thicknesses of monolithic LYSO:Ce (cerium-doped lutetium yttrium orthosilicate) are being studied to understand brightness and resolution trade-offs compared with a range of micro-columnar CsI:Tl (thallium-doped cesium iodide) scintillator screens. The micro-columnar scintillator structure apparently provides an optical gain mechanism that results in brighter signals from thinner samples. The trade-offs for brightness versus resolution in monolithic scintillators is straightforward. For higher-energy x-rays, thicker materials generally produce brighter signal due to x-ray absorption and the optical emission properties of the material. However, as scintillator thickness is increased, detector blur begins to dominate imaging system resolution due to the volume image generated in the scintillator thickness and the depth of field of the imaging system. We employ a telecentric optical relay lens to image the scintillator onto a recording CCD camera. The telecentric lens helps provide sharp focus through thicker-volume emitting scintillators. Stray light from scintillator emission can also affect the image scene contrast. We have applied an optical light scatter model to the imaging system to minimize scatter sources and maximize scene contrasts.

Baker, Stuart; Brown, Kristina; Curtis, Alden; Lutz, Stephen S.; Howe, Russell; Malone, Robert; Mitchell, Stephen; Danielson, Jeremy; Haines, Todd; Kwiatkowski, Kris

2014-09-01

364

Status report on dark matter search with low activity scintillators  

NASA Astrophysics Data System (ADS)

The BPRS experiment is dedicated to particle Dark Matter search with low activity scintillators. Preliminary results on Weakly Interacting Massive Particles (WIMPs) have been already obtained with NaI(Tl) and CaF 2(Eu) target-detectors. New detector developments are in progress. A new search for Strongly Interacting Massive Particles (SIMPs) with NaI(Tl) scintillators have been also performed.

Bacci, C.; Belli, P.; Bernabei, R.; Dai, C.; Di Nicolantonio, W.; Ding, L. K.; Gaillard-Lecanu, E.; Giraud-Heraud, Y.; Kuang, H. H.; Incicchitti, A.; Mallet, J.; Mosca, L.; Prosperi, D.; Tao, C.; Chambon, B.; Chazal, V.; De Jésus, M.; Drain, D.; Messous, Y.; Pastor, C.; BPRS (Beijing, Paris, Roma, Saclay) Collaboration

1994-05-01

365

Analysis of the response of capture-gated organic scintillators  

Microsoft Academic Search

Recent efforts have been aimed at investigating neutron detectors based on the combined signal from capture-gated organic scintillators. We present a Monte Carlo approach that is based on the simulation of the neutron detector response on an event-by-event basis. Detection efficiency, scintillator pulse height, and time-to-capture are among the quantities that can be estimated by the Monte Carlo technique

Sara A. Pozzi; Richard B. Oberer; John S. Neal

2005-01-01

366

Analysis of the response of capture-gated organic scintillators  

Microsoft Academic Search

Recent efforts have been aimed at investigating neutron detectors based on the combined signal from capture-gated organic scintillators. We present a Monte Carlo approach that is based on the simulation of the neutron detector response on an event-by-event basis. Detection efficiency, scintillator pulse height, and time-to-capture are among the quantities that can be estimated by the Monte Carlo technique.

Sara A. Pozzi; Richard B. Oberer; John S. Neal

2004-01-01

367

Liquid-helium scintillation detection with germanium photodiodes  

SciTech Connect

Special high-purity germanium photodiodes have been developed for the direct detection of vacuum ultraviolet scintillations in liquid helium. The photodiodes are immersed in the liquid helium, and scintillations are detected through one of the bare sides of the photodiodes. Test results with scintillation photons produced by 5.3-MeV ..cap alpha.. particles are presented. The use of these photodiodes as liquid-helium scintillation detectors may offer substantial improvements over the alternate detection method requiring the use of wavelength shifters and photomultiplier tubes.

Luke, P.N.; Haller, E.E.; Steiner, H.M.

1982-05-01

368

Results from the HERMES Recoil Detector Sergey Yaschenko  

E-print Network

Scintillating Fiber Tracker (SFT) 2 barrels of scintillation fibers with 2 parallel and 2 stereo layers Lepton Scintillating Fiber Tracker (SFT) 2 cylinders: ­ 2 layers parallel to the beam axis ­ 2 stereo layers at 10 Detector Status All sub-detectors are calibrated ­ SFT and PD with positively and negatively charged pions

369

Improved event positioning in a gamma ray detector using an iterative position-weighted centre-of-gravity algorithm  

NASA Astrophysics Data System (ADS)

An iterative position-weighted centre-of-gravity algorithm was developed and tested for positioning events in a silicon photomultiplier (SiPM)-based scintillation detector for positron emission tomography. The algorithm used a Gaussian-based weighting function centred at the current estimate of the event location. The algorithm was applied to the signals from a 4 × 4 array of SiPM detectors that used individual channel readout and a LYSO:Ce scintillator array. Three scintillator array configurations were tested: single layer with 3.17 mm crystal pitch, matched to the SiPM size; single layer with 1.5 mm crystal pitch; and dual layer with 1.67 mm crystal pitch and a ½ crystal offset in the X and Y directions between the two layers. The flood histograms generated by this algorithm were shown to be superior to those generated by the standard centre of gravity. The width of the Gaussian weighting function of the algorithm was optimized for different scintillator array setups. The optimal width of the Gaussian curve was found to depend on the amount of light spread. The algorithm required less than 20 iterations to calculate the position of an event. The rapid convergence of this algorithm will readily allow for implementation on a front-end detector processing field programmable gate array for use in improved real-time event positioning and identification.

Liu, Chen-Yi; Goertzen, Andrew L.

2013-07-01

370

Improved event positioning in a gamma ray detector using an iterative position-weighted centre-of-gravity algorithm.  

PubMed

An iterative position-weighted centre-of-gravity algorithm was developed and tested for positioning events in a silicon photomultiplier (SiPM)-based scintillation detector for positron emission tomography. The algorithm used a Gaussian-based weighting function centred at the current estimate of the event location. The algorithm was applied to the signals from a 4 × 4 array of SiPM detectors that used individual channel readout and a LYSO:Ce scintillator array. Three scintillator array configurations were tested: single layer with 3.17 mm crystal pitch, matched to the SiPM size; single layer with 1.5 mm crystal pitch; and dual layer with 1.67 mm crystal pitch and a ½ crystal offset in the X and Y directions between the two layers. The flood histograms generated by this algorithm were shown to be superior to those generated by the standard centre of gravity. The width of the Gaussian weighting function of the algorithm was optimized for different scintillator array setups. The optimal width of the Gaussian curve was found to depend on the amount of light spread. The algorithm required less than 20 iterations to calculate the position of an event. The rapid convergence of this algorithm will readily allow for implementation on a front-end detector processing field programmable gate array for use in improved real-time event positioning and identification. PMID:23798644

Liu, Chen-Yi; Goertzen, Andrew L

2013-07-21

371

Neutrino Detectors: Challenges and Opportunities  

SciTech Connect

This paper covers possible detector options suitable at future neutrino facilities, such as Neutrino Factories, Super Beams and Beta Beams. The Magnetised Iron Neutrino Detector (MIND), which is the baseline detector at a Neutrino Factory, will be described and a new analysis which improves the efficiency of this detector at low energies will be shown. Other detectors covered include the Totally Active Scintillating Detectors (TASD), particularly relevant for a low energy Neutrino Factory, emulsion detectors for tau detection, liquid argon detectors and megaton scale water Cherenkov detectors. Finally the requirements of near detectors for long-baseline neutrino experiments will be demonstrated.

Soler, F. J. P. [School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

2011-10-06

372

Scintillator Replacement Option for BaBar  

SciTech Connect

A replacement technology for the muon detection system in BaBar using scintillator bars with Wavelength Shifting (WLS) fibers and Avalanche Photo Diodes (APDs). APDs must be used in BaBar due to the high magnetic fields that disrupt the electron multiplying effects of Photo Multiplier Tubes (PMTs). Muons passing through scintillator cause fluors in the scintillator to emit photons, which are captured by WLS fibers and then re-emitted at the ends of the fibers to awaiting APDs. The detector configuration that will produce the largest Light Yield (LY) and produce a clear APD signal that will be larger than background noise is the main goal of the study. Bar dimensions, number of WLS fibers, and placement of fibers are parameters that may be adjusted to produce the largest LY. Additionally, good timing resolution is needed to determine where a muon passed through the detector along the long direction of the bar. A scintillator bar 2cm x 4cm in x-y with four round lmm fibers produced the largest LY out of four different configurations with a timing resolution of 25cm. A Monte Carlo simulation confirmed the relative LY compared to other detectors. This detector was able to produce a 40mV pulse from the APD that was easily discernable above the 2-SmV background noise. Refinement of the fabrication process could produced higher LYs and better timing resolutions, while a redesign of the electronics may increase the signal to noise ratio.

Lometti, m

2004-02-05

373

Fluorescent compounds for plastic scintillation applications  

SciTech Connect

Several 2-(2{prime}-hydroxyphenyl)benzothiazole, -benzoxazole, and -benzimidazole derivatives have been prepared. Transmittance, fluorescence, light yield, and decay time characteristics of these compounds have been studied in a polystyrene matrix and evaluated for use in plastic scintillation detectors. Radiation damage studies utilizing a {sup 60}C source have also been performed.

Pla-Dalmau, A.; Bross, A.D.

1994-04-01

374

Scintillator materials for calorimetry  

SciTech Connect

Requirements for fast, dense scintillator materials for calorimetry in high energy physics and approaches to satisfying these requirements are reviewed with respect to possible hosts and luminescent species. Special attention is given to cerium-activated crystals, core-valence luminescence, and glass scintillators. The present state of the art, limitations, and suggestions for possible new scintillator materials are presented.

Weber, M.J. [Lawrence Berkeley Lab., CA (United States). Life Sciences Div.

1994-09-01

375

Scintillator manufacture at Fermilab  

SciTech Connect

A decade of research into plastic scintillation materials at Fermilab is reviewed. Early work with plastic optical fiber fabrication is revisited and recent experiments with large-scale commercial methods for production of bulk scintillator are discussed. Costs for various forms of scintillator are examined and new development goals including cost reduction methods and quality improvement techniques are suggested.

Mellott, K.; Bross, A.; Pla-Dalmau, A.

1998-08-01

376

Investigation of LaBr3:Ce scintillator with excellent property  

NASA Astrophysics Data System (ADS)

In order to satisfy high precision requirement for the modern nuclear physics experiment detectors and radiologic imaging technology equipments, we do some researches in improving the resolution of the detector with LaBr3:Ce scintillator.

Chen, Jin-da; Hu, Zheng-guo; Zhang, Xiu-ling; Chen, Ze; Yuan, Xiao-hua; Sun, Zhi-yu; Guo, Zhong-yan; Xu, Hu-shan

2014-04-01

377

Scintillator reflective layer coextrusion  

DOEpatents

A polymeric scintillator has a reflective layer adhered to the exterior surface thereof. The reflective layer comprises a reflective pigment and an adhesive binder. The adhesive binder includes polymeric material from which the scintillator is formed. A method of forming the polymeric scintillator having a reflective layer adhered to the exterior surface thereof is also provided. The method includes the steps of (a) extruding an inner core member from a first amount of polymeric scintillator material, and (b) coextruding an outer reflective layer on the exterior surface of the inner core member. The outer reflective layer comprises a reflective pigment and a second amount of the polymeric scintillator material.

Yun, Jae-Chul (Naperville, IL); Para, Adam (St. Charles, IL)

2001-01-01

378

Simulations and developments of the Low Energy Neutron detector Array LENA  

NASA Astrophysics Data System (ADS)

Prototypes of the Low Energy Neutron detector Array (LENA) have been tested and compared with detailed GEANT simulations. LENA will consist of plastic scintillation bars with the dimensions 1000×45×10 mm3. The tests have been performed with ?-ray sources and neutrons originating from the neutron-induced fission of 235U. The simulations agreed very well with the measured response and were therefore used to simulate the response to mono-energetic neutrons with different detection thresholds. LENA will be used to detect low-energy neutrons from (p,n)-type reactions with low momentum transfer foreseen at the R3B and EXL setups at FAIR, Darmstadt.

Langer, C.; Algora, A.; Couture, A.; Csatlós, M.; Gulyás, J.; Heil, M.; Krasznahorkay, A.; O'Donnell, J. M.; Plag, R.; Reifarth, R.; Stuhl, L.; Sonnabend, K.; Tornyi, T.; Tovesson, F.

2011-12-01

379

Majorana Thermosyphon Prototype Experimental Setup  

SciTech Connect

This report presents the experimental setup of Pacific Northwest National Laboratory’s MAJORANA DEMONSTRATOR thermosyphon prototype cooling system. A nitrogen thermosyphon prototype of such a system has been built and tested at PNNL. This document presents the experimental setup of the prototype that successfully demonstrated the heat transfer performance of the system.

Reid, Douglas J.; Guzman, Anthony D.; Munley, John T.

2011-08-01

380

Multi-PSPMT scintillation camera  

SciTech Connect

Gamma ray imaging is usually accomplished by the use of a relatively large scintillating crystal coupled to either a number of photomultipliers (PMTs) (Anger Camera) or to a single large Position Sensitive PMT (PSPMT). Recently the development of new diagnostic techniques, such as scintimammography and radio-guided surgery, have highlighted a number of significant limitations of the Anger camera in such imaging procedures. In this paper a dedicated gamma camera is proposed for clinical applications with the aim of improving image quality by utilizing detectors with an appropriate size and shape for the part of the body under examination. This novel scintillation camera is based upon an array of PSPMTs (Hamamatsu R5900-C8). The basic concept of this camera is identical to the Anger Camera with the exception of the substitution of PSPMTs for the PMTs. In this configuration it is possible to use the high resolution of the PSPMTs and still correctly position events lying between PSPMTs. In this work the test configuration is a 2 by 2 array of PSPMTs. Some advantages of this camera are: spatial resolution less than 2 mm FWHM, good linearity, thickness less than 3 cm, light weight, lower cost than equivalent area PSPMT, large detection area when coupled to scintillating arrays, small dead boundary zone (< 3 mm) and flexibility in the shape of the camera.

Pani, R.; Pellegrini, R.; Trotta, G.; Scopinaro, F. [Univ. of Rome (Italy). Dept. of Experimental Medicine] [Univ. of Rome (Italy). Dept. of Experimental Medicine; Soluri, A.; Vincentis, G. de [CNR (Italy). Inst. of Biomedical Technologies] [CNR (Italy). Inst. of Biomedical Technologies; Scafe, R. [ENEA-INN, Rome (Italy)] [ENEA-INN, Rome (Italy); Pergola, A. [PSDD, Rome (Italy)] [PSDD, Rome (Italy)

1999-06-01

381

Novel method for hit-position reconstruction using voltage signals in plastic scintillators and its application to Positron Emission Tomography  

E-print Network

Currently inorganic scintillator detectors are used in all commercial Time of Flight Positron Emission Tomograph (TOF-PET) devices. The J-PET collaboration investigates a possibility of construction of a PET scanner from plastic scintillators which would allow for single bed imaging of the whole human body. This paper describes a novel method of hit-position reconstruction based on sampled signals and an example of an application of the method for a single module with a 30 cm long plastic strip, read out on both ends by Hamamatsu R4998 photomultipliers. The sampling scheme to generate a vector with samples of a PET event waveform with respect to four user-defined amplitudes is introduced. The experimental setup provides irradiation of a chosen position in the plastic scintillator strip with an annihilation gamma quanta of energy 511~keV. The statistical test for a multivariate normal (MVN) distribution of measured vectors at a given position is developed, and it is shown that signals sampled at four threshold...

Raczynski, L; Kowalski, P; Wislicki, W; Bednarski, T; Bialas, P; Czerwinski, E; Kaplon, L; Kochanowski, A; Korcyl, G; Kowal, J; Kozik, T; Krzemien, W; Kubicz, E; Molenda, M; Moskal, I; Niedzwiecki, Sz; Palka, M; Pawlik-Niedzwiecka, M; Rudy, Z; Salabura, P; Sharma, N G; Silarski, M; Slomski, A; Smyrski, J; Strzelecki, A; Wieczorek, A; Zielinski, M; Zon, N

2014-01-01

382

Novel method for hit-position reconstruction using voltage signals in plastic scintillators and its application to Positron Emission Tomography  

E-print Network

Currently inorganic scintillator detectors are used in all commercial Time of Flight Positron Emission Tomograph (TOF-PET) devices. The J-PET collaboration investigates a possibility of construction of a PET scanner from plastic scintillators which would allow for single bed imaging of the whole human body. This paper describes a novel method of hit-position reconstruction based on sampled signals and an example of an application of the method for a single module with a 30 cm long plastic strip, read out on both ends by Hamamatsu R4998 photomultipliers. The sampling scheme to generate a vector with samples of a PET event waveform with respect to four user-defined amplitudes is introduced. The experimental setup provides irradiation of a chosen position in the plastic scintillator strip with an annihilation gamma quanta of energy 511~keV. The statistical test for a multivariate normal (MVN) distribution of measured vectors at a given position is developed, and it is shown that signals sampled at four thresholds in a voltage domain are approximately normally distributed variables. With the presented method of a vector analysis made out of waveform samples acquired with four thresholds, we obtain a spatial resolution of about 1 cm and a timing resolution of about 80 ps

L. Raczynski; P. Moskal; P. Kowalski; W. Wislicki; T. Bednarski; P. Bialas; E. Czerwinski; L . Kaplon; A. Kochanowski; G. Korcyl; J. Kowal; T. Kozik; W. Krzemien; E. Kubicz; M. Molenda; I. Moskal; Sz. Niedzwiecki; M. Palka; M. Pawlik-Niedzwiecka; Z. Rudy; P. Salabura; N. G. Sharma; M. Silarski; A. Slomski; J. Smyrski; A. Strzelecki; A. Wieczorek; M. Zielinski; N. Zon

2014-07-31

383

Novel method for hit-position reconstruction using voltage signals in plastic scintillators and its application to Positron Emission Tomography  

NASA Astrophysics Data System (ADS)

Currently inorganic scintillator detectors are used in all commercial Time of Flight Positron Emission Tomograph (TOF-PET) devices. The J-PET collaboration investigates a possibility of construction of a PET scanner from plastic scintillators which would allow for single bed imaging of the whole human body. This paper describes a novel method of hit-position reconstruction based on sampled signals and an example of an application of the method for a single module with a 30 cm long plastic strip, read out on both ends by Hamamatsu R4998 photomultipliers. The sampling scheme to generate a vector with samples of a PET event waveform with respect to four user-defined amplitudes is introduced. The experimental setup provides irradiation of a chosen position in the plastic scintillator strip with an annihilation gamma quanta of energy 511 keV. The statistical test for a multivariate normal (MVN) distribution of measured vectors at a given position is developed, and it is shown that signals sampled at four thresholds in a voltage domain are approximately normally distributed variables. With the presented method of a vector analysis made out of waveform samples acquired with four thresholds, we obtain a spatial resolution of about 1 cm and a timing resolution of about 80 ps (?).

Raczy?ski, L.; Moskal, P.; Kowalski, P.; Wi?licki, W.; Bednarski, T.; Bia?as, P.; Czerwi?ski, E.; Kap?on, ?.; Kochanowski, A.; Korcyl, G.; Kowal, J.; Kozik, T.; Krzemie?, W.; Kubicz, E.; Molenda, M.; Moskal, I.; Nied?wiecki, Sz.; Pa?ka, M.; Pawlik-Nied?wiecka, M.; Rudy, Z.; Salabura, P.; Sharma, N. G.; Silarski, M.; S?omski, A.; Smyrski, J.; Strzelecki, A.; Wieczorek, A.; Zieli?ski, M.; Zo?, N.

2014-11-01

384

Neutrino tracking calorimetry with plastic scintillator bars  

NASA Astrophysics Data System (ADS)

The technique of plastic scintillator bars coupled to wavelength shifting fibers is proposed for neutrino tracking calorimeters, in the context of very large, massive detectors for experiments on the neutrino factory beam. A prototype has been built with 180 scintillator bars interleaved with an equal number of iron bars. The light from the fibers is collected by multi-anode PMTs and converted with Amplitude-Time-Pattern self-triggering digitizing electronics. The prototype has been tested with electron and pion beams at CERN.

Giannini, Gianrossano; Santin, Giovanni; Spinetti, Mario; Votano, Lucia; Hoepfner, Kerstin

2001-10-01

385

Adaptive spatially resolving detector for the extreme ultraviolet with absolute measuring capability  

SciTech Connect

A spatially resolving detector for the extreme ultraviolet (XUV) and soft x-ray spectral region is presented. Principle of operation is conversion of XUV radiation to visible light by a scintillator crystal. Luminescence is detected using charge coupled device camera and imaging optics. Single layer and multilayer coatings are applied to match the system to different spectral regions of interest. Field of view and spatial resolution can be adapted to the application. Calibration of the system enables to absolutely measure in-band radiation flux on the scintillator. The setup is designed for the characterization and optimization of XUV sources and XUV optical systems. Measurements, carried out to characterize the focus in a soft x-ray microscope, are presented as an application example.

Benk, Markus; Bergmann, Klaus [Fraunhofer Institute for Laser Technology, Steinbachstrasse 15, D-52074 Aachen (Germany)

2009-03-15

386

New electronically black neutron detectors  

SciTech Connect

Two neutron detectors are described that can function in a continuous radiation background. Both detectors identify neutrons by recording a proton recoil pulse followed by a characteristic capture pulse. This peculiar signature indicates that the neutron has lost all its energy in the scintillator. Resolutions and efficiencies have been measured for both detectors.

Drake, D.M.; Feldman, W.C.; Hurlbut, C.

1986-03-01

387

Counterintuitive MCNPX Results for Scintillator Surface Roughness Effect  

SciTech Connect

We have reported on our recent MCNPX simulation results of energy deposition for a group of 8 scintillation detectors, coupled with various rough surface patterns. The MCNPX results generally favored the detectors with various rough surface patterns. The observed MCNPX results are not fully explained by this work.

None

2012-08-12

388

Flexible composite radiation detector  

DOEpatents

A flexible composite scintillator was prepared by mixing fast, bright, dense rare-earth doped powdered oxyorthosilicate (such as LSO:Ce, LSO:Sm, and GSO:Ce) scintillator with a polymer binder. The binder is transparent to the scintillator emission. The composite is seamless and can be made large and in a wide variety of shapes. Importantly, the composite can be tailored to emit light in a spectral region that matches the optimum response of photomultipliers (about 400 nanometers) or photodiodes (about 600 nanometers), which maximizes the overall detector efficiency.

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

2006-12-05

389

Neutron Scattering Facility for Characterization of CRESST and EURECA Detectors at mK Temperatures  

E-print Network

CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) is an experiment located at the Gran Sasso underground laboratory and aimed at the direct detection of dark matter in the form of WIMPs. The setup has just completed a one year commissioning run in 2007 and is presently starting a physics run with an increased target mass. Scintillating $\\mathrm{CaWO_4}$ single crystals, operated at temperatures of a few millikelvin, are used as target to detect the tiny nuclear recoil induced by a WIMP. The powerful background identification and rejection of $\\alpha$, e$^{-}$ and $\\gamma$ events is realized via the simultaneous measurement of a phonon and a scintillation signal generated in the $\\mathrm{CaWO_4}$ crystal. However, neutrons could still be misidentified as a WIMP signature. Therefore, a detailed understanding of the individual recoil behaviour in terms of phonon generation and scintillation light emission due to scattering on Ca, O or W nuclei, respectively, is mandatory. The only setup which allows to perform such measurements at the operating temperature of the CRESST detectors has been installed at the Maier-Leibnitz-Accelerator Laboratory in Garching and is presently being commissioned. The design of this neutron scattering facility is such that it can also be used for other target materials, e.g. $\\mathrm{ZnWO_4}$, $\\mathrm{PbWO_4}$ and others as foreseen in the framework of the future multitarget tonne-scale experiment EURECA (European Underground Rare Event Calorimeter Array).

J. -C. Lanfranchi; C. Ciemniak; C. Coppi; F. von Feilitzsch; A. Gütlein; H. Hagn; C. Isaila; J. Jochum; M. Kimmerle; S. Pfister; W. Potzel; W. Rau; S. Roth; K. Rottler; C. Sailer; S. Scholl; I. Usherov; W. Westphal

2008-10-01

390

Calibration of the Thick and Thin Scintillators for the NSCL/FSU Sweeper Magnet System  

NASA Astrophysics Data System (ADS)

The MoNA (Modular Neutron Array) Sweeper-magnet setup at the NSCL is designed to measure neutron unbound states by full kinematic reconstruction of the neutrons and the decay fragments. One crucial aspect of these coincidence experiments is the particle identification of the charged fragments in the focal plane detectors following the sweeper magnet. The particle ID is achieved by the measurement of the energy-loss and total kinetic energy in large thin and thick plastic scintillation detectors, respectively. The pulse-height of the signals from these detectors is strongly position dependent. In order to achieve accurate Delta-E/E-identification for the fragments it is thus necessary to correct for these position dependencies. A procedure was developed to implement this correction quickly and efficiently for the on-line analysis. The procedure is based on Tcl-scripts sourced in the analysis program SpecTcl in combination with fitting routines in Excel. The performance of this procedure will be presented with data from experiment 05124, which studied neutron unbound states close to the neutron dripline.

Hayes, Anne

2006-10-01

391

Collider shot setup for Run 2 observations and suggestions  

SciTech Connect

This note is intended to provoke discussion on Collider Run II shot setup. We hope this is a start of activities that will converge on a functional description of what is needed for shot setups in Collider Run II. We will draw on observations of the present shot setup to raise questions and make suggestions for the next Collider run. It is assumed that the reader has some familiarity with the Collider operational issues. Shot setup is defined to be the time between the end of a store and the time the Main Control Room declares colliding beams. This is the time between Tevatron clock events SCE and SCB. This definition does not consider the time experiments use to turn on their detectors. This analysis was suggested by David Finley. The operational scenarios for Run II will require higher levels of reliability and speed for shot setup. See Appendix I and II. For example, we estimate that a loss of 3 pb{sup {minus}1}/week (with 8 hour stores) will occur if shot setups take 90 minutes instead of 30 minutes. In other words: If you do 12 shots for one week and accept an added delay of one minute in each shot, you will loose more than 60 nb{sup {minus}1} for that week alone (based on a normal shot setup of 30 minutes). These demands should lead us to be much more pedantic about all the factors that affect shot setups. Shot setup will be viewed as a distinct process that is composed of several inter- dependent `components`: procedures, hardware, controls, and sociology. These components don`t directly align with the different Accelerator Division departments, but are topical groupings of the needed accelerator functions. Defining these components, and categorizing our suggestions within them, are part of the goal of this document. Of course, some suggestions span several of these components.

Annala, J.; Joshel, B.

1996-01-31

392

The response of scintillators to heavy ions: 1, Plastics  

SciTech Connect

The response of various scintillator detectors to ions of A = 1-84 and energies E/A = 5 to 30 MeV have been measured, and are found to be linear above an energy of 100 MeV. Results are presented for a typical organic plastic scintillator including parametrizations of the data as a function of Z, A, and energy. These results can be used by anyone using scintillators as heavy ion detectors, with one calibration point giving a normalization that allows use of the whole set of curves. The response functions are compared to previous parametrizations at lower energies and discussed in terms of the theory of delta-ray formation in the scintillator.

McMahan, M.A.

1987-10-01

393

Performance of Water-based Liquid Scintillator  

NASA Astrophysics Data System (ADS)

Water-based detectors can only see the Cherenkov light from the fast moving charged particles, thus missing all the particles below the Cherenkov threshold. Detecting these below-threshold particles is important for various applications like the mobile detectors for the nuclear reactor monitoring, the search of the proton decay, and reconstruction of the neutrino energy and the reaction type by observing the vertex activity for both long and short baseline experiments. This detection can be achieved by using the Water-based Liquid Scintillator (WbLS), currently under development. It is based on the idea of dissolving the organic scintillator in water using special surfactants. This new material strives to achieve the novel detection techniques by combining the Cherenkov rings and scintillation light, as well as the total cost reduction compared to pure liquid scintillator (LS). We will present light yield measurements for the proton beam energies of 210MeV, 475MeV and 2000MeV for water, two different WbLS formulations (1% and 4%) and pure LS. These beam energies were chosen to study the contribution of the Cherenkov light to the total output.