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1

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

Microsoft Academic Search

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

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

2002-01-01

2

Composite scintillator screen  

DOEpatents

A scintillator screen for an X-ray system includes a substrate of low-Z material and bodies of a high-Z material embedded within the substrate. By preselecting the size of the bodies embedded within the substrate, the spacial separation of the bodies and the thickness of the screen, the sensitivity of the screen to X-rays within a predetermined energy range can be predicted.

Zeman, Herbert D. (1687 Peach St., Memphis, TN 38112)

1994-01-01

3

Screen Study Guides.  

ERIC Educational Resources Information Center

This study guide for Arthur Lipsett's film "Very Nice, Very Nice" is in four parts. First, it describes and evaluates the film, discusses Lipsett's unusual juxtapositions, fast cutting, and fragmented speeches as indications of his satirical intent, and suggests that the only meaningful summation of the film's content is through pattern…

Duncan, Barry

1969-01-01

4

Synthesis Coupled to Scintillation Proximity Affinity Screening  

Microsoft Academic Search

The rapidly changing developments in genomics and combinatorial chemistry, generating new drug targets and large numbers of compounds, are beginning to push the limits of screening efficiently. Thus, there is a need for novel tools and strategies to improve high throughput screening. A novel approach is to couple synthesis and screening on a common platform, rather than to increase the

Zahra Parandoosh; Sue K. Knowles; Xiao-Yi Xiao; Chanfeng Zhao; Gary S. David; Michael P. Nova

1998-01-01

5

Absolute charge calibration of scintillating screens for relativistic electron detection  

NASA Astrophysics Data System (ADS)

We report on new charge calibrations and linearity tests with high-dynamic range for eight different scintillating screens typically used for the detection of relativistic electrons from laser-plasma based acceleration schemes. The absolute charge calibration was done with picosecond electron bunches at the ELBE linear accelerator in Dresden. The lower detection limit in our setup for the most sensitive scintillating screen (KODAK Biomax MS) was 10 fC/mm2. The screens showed a linear photon-to-charge dependency over several orders of magnitude. An onset of saturation effects starting around 10-100 pC/mm2 was found for some of the screens. Additionally, a constant light source was employed as a luminosity reference to simplify the transfer of a one-time absolute calibration to different experimental setups.

Buck, A.; Zeil, K.; Popp, A.; Schmid, K.; Jochmann, A.; Kraft, S. D.; Hidding, B.; Kudyakov, T.; Sears, C. M. S.; Veisz, L.; Karsch, S.; Pawelke, J.; Sauerbrey, R.; Cowan, T.; Krausz, F.; Schramm, U.

2010-03-01

6

Performance of thin foil scintillating screen for transmission electron microscopy.  

PubMed

Scintillating screens made by coating a thin metal foil with a layer of phosphor appear to be attractive for transmission electron microscopy applications. We report here the brightness and resolution in the voltage range of 100-400 kV of such a screen made of a 10 microns layer of P20 phosphor on a 2 microns Al foil. Both brightness and resolution are superior to that of a screen made by coating a glass plate with a similar layer of phosphor. An exciting property of such a device is that its resolution improves slightly at higher voltages. This, combined with its excellent resistivity to radiation damage and stability under the electron beam, makes it a good candidate for high-voltage applications. PMID:7974848

Fan, G Y; Dunkelberger, D G; Ellisman, M H

1994-07-01

7

Optimization of screening for radioactivity in urine by liquid scintillation.  

SciTech Connect

Numerous events have or could have resulted in the inadvertent uptake of radionuclides by fairly large populations. Should a population receive an uptake, valuable information could be obtained by using liquid scintillation counting (LSC) techniques to quickly screen urine from a sample of the affected population. This study investigates such LSC parameters as discrimination, quench, volume, and count time to yield guidelines for analyzing urine in an emergency situation. Through analyzing variations of the volume and their relationships to the minimum detectable activity (MDA), the optimum ratio of sample size to scintillating chemical cocktail was found to be 1:3. Using this optimum volume size, the alpha MDA varied from 2100 pCi/L for a 30-second count time to 35 pCi/L for a 1000-minute count time. The typical count time used by the Sandia National Laboratories Radiation Protection Sample Diagnostics program is 30 minutes, which yields an alpha MDA of 200 pCi/L. Because MDA is inversely proportional to the square root of the count time, count time can be reduced in an emergency situation to achieve the desired MDA or response time. Note that approximately 25% of the response time is used to prepare the samples and complete the associated paperwork. It was also found that if the nuclide of interest is an unknown, pregenerated discriminator settings and efficiency calibrations can be used to produce an activity value within a factor of two, which is acceptable for a screening method.

Shanks, Sonoya Toyoko; Reese, Robert P.; Preston, Rose T. (Technadyne Engineering Consultants, Inc., Albuquerque, NM)

2007-08-01

8

Estimating the amplitude scintillation index from sparsely sampled phase screen data  

Microsoft Academic Search

Phase screen techniques are commonly used to model scintillation of radio signals passing through a disturbed ionosphere, but observational phase or in situ density from both archival and real-time sources is often sampled at rates well below the resolution desired for input to such models. Previous phase screen resolution criteria do not address the computation of the amplitude scintillation index

T. L. Beach; T. R. Pedersen; M. J. Starks; S.-Y. Su

2004-01-01

9

Scintillating screens sensitivity and resolution studies for low energy, low intensity beam diagnostics  

SciTech Connect

In order to investigate the limits of scintillating screens for beam profile monitoring in the ultra-low energy, ultra-low intensity regime, CsI:Tl, YAG:Ce, and a Tb glass-based scintillating fiber optic plate (SFOP) were tested. The screens response to 200 and 50 keV proton beams with intensities ranging from a few picoampere down to the subfemtoampere region was examined. In the following paper, the sensitivity and resolution studies are presented in detail for CsI:Tl and the SFOP, the two most sensitive screens. In addition, a possible use of scintillators for ultra-low energy antiproton beam monitoring is discussed.

Harasimowicz, Janusz; Welsch, Carsten P. [Cockcroft Institute, Warrington WA4 4AD (United Kingdom); Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Cosentino, Luigi; Finocchiaro, Paolo; Pappalardo, Alfio [National Institute of Nuclear Physics INFN-LNS, Catania 95125 (Italy)

2010-10-15

10

Cerenkov-free scintillation dosimetry in external beam radiotherapy with an air core light guide.  

PubMed

Plastic scintillators have many advantages for dosimetry in external beam radiotherapy. The current method of transmitting the scintillation light to a remote detector is through a solid core optical fibre. When exposed in a high energy therapeutic radiotherapy beam this fibre is subject to an unwanted background signal from Cerenkov light which can exceed the scintillation signal at characteristic angles. We have constructed a plastic scintillation dosimeter that uses an air core light guide to transport the light from the scintillator to the light detector. We show that there is sufficient signal propagation in the air core light guide to allow the scintillator signal to be carried outside the primary beam of a radiotherapy linear accelerator and for a dosimeter to be constructed using a scintillator inserted into the end of the light guide. Studies of the background light generated in the air core light guide, as a function of the angle between the beam and the fibre axis, show that there is no characteristic Cerenkov peak generated in the air core. Depth dose measurements using the air core scintillation dosimeter with no correction for Cerenkov are compared to ionization chamber measurements for a 6 MV photon beam and a 9 MeV electron beam. PMID:18490811

Lambert, J; Yin, Y; McKenzie, D R; Law, S; Suchowerska, N

2008-06-01

11

Waste-to-energy screening guide  

SciTech Connect

Waste-to-energy (WTE) involves the combustion of municipal solid waste (MSW) and the production of steam and electricity. It has been, and continues to be, an issue of importance to utilities because WTE projects provide an alternative source of electricity to that being provided by the utility. In fact, utilities purchase most of the energy generated by WTE projects. Furthermore, waste-to-energy projects provide a societal benefit: an alternative to landfill disposal of waste. The Waste-to-Energy Screening Guide contains reference materials and estimating tools to assist utilities in evaluating potential waste-to-energy projects. It was produced as part of the Electric Power Research Institute (EPRI) Waste-to-Energy Screening and Permitting Guide'' project, RP2190-5. The Guide is organized into the following major parts: Introduction to MSW combustion, Technology analyses, Economics Qualitative issues analyses, Software for technology screening. The advantages and disadvantages of the different technologies are described, issues are discussed, and a qualitative evaluation procedure is provided. Performance and environmental data are summarized. Costs and revenues are estimated, and equations and a computer model are provided so that users can screen the technologies on the basis of economics. WTE technologies described in the provide a wide range of viable technologies of interest to utilities considering WTE projects: mass burn, refuse-derived fuel, recycling and material recycling facilities, MSW landfills, and ash processing and disposal, including ash monofills.

Hohman, E.H. (Bechtel Group, Inc., San Francisco, CA (United States))

1992-08-01

12

Development of phase-separated scintillators with light-guiding properties.  

PubMed

Alkali halide systems that function as phase-separated scintillators (PSSs) with light-guiding properties are sucessfully created. Furthermore, it is the matrix phases of the PSSs which display the light-guiding properties. CsI-NaCl:Tl is a practical material pair because of its high pixel light output and good spatial resolution. PMID:22887761

Yasui, Nobuhiro; Ohashi, Yoshihiro; Kobayashi, Tamaki; Den, Tohru

2012-10-23

13

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

SciTech Connect

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

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

2008-05-12

14

Scintillating screens sensitivity and resolution studies for low energy, low intensity beam diagnostics.  

PubMed

In order to investigate the limits of scintillating screens for beam profile monitoring in the ultra-low energy, ultra-low intensity regime, CsI:Tl, YAG:Ce, and a Tb glass-based scintillating fiber optic plate (SFOP) were tested. The screens response to 200 and 50 keV proton beams with intensities ranging from a few picoampere down to the subfemtoampere region was examined. In the following paper, the sensitivity and resolution studies are presented in detail for CsI:Tl and the SFOP, the two most sensitive screens. In addition, a possible use of scintillators for ultra-low energy antiproton beam monitoring is discussed. PMID:21034082

Harasimowicz, Janusz; Cosentino, Luigi; Finocchiaro, Paolo; Pappalardo, Alfio; Welsch, Carsten P

2010-10-01

15

Using Thin Films to Screen Possible Scintillator Materials  

SciTech Connect

The discovery and optimization of new scintillators has traditionally been a rather slow process due to the difficulties of single crystal growth. This paper discusses the production of polycrystalline scintillator thin films (a few microns thick) which were tested in order to determine what characterizations could be made concerning a material’s ultimate potential as a scintillator prior to pursuing crystal growth. Thin films of CaF2(Eu), CeF3, and CeCl3, all known scintillators, were produced by vapor deposition. The hygroscopic CeCl3 was coated with multiple polymer-aluminum oxide bi-layers. Emission spectra peak wavelengths and decay times agreed with single crystal values. The films were too thin to measure gamma photopeaks, but using alpha energy deposition peaks, one could compare the relative photon yield/MeV between materials. The values obtained appear to give a relevant indication of a material’s light yield potential. The technique also appears useful for quickly determining the proper dopant amount for a given material.

Milbrath, Brian D.; Caggiano, Joseph A.; Engelhard, Mark H.; Joly, Alan G.; Matson, Dean W.; Nachimuthu, Ponnusamy; Olsen, Larry C.

2009-06-30

16

A pedestrian's guide to radiation damage in plastic scintillators  

Microsoft Academic Search

The planned construction of new high energy, high luminosity hadron colliders (the SSC in the United States and the LHC in Europe) has renewed an interest in the particle physics community in the design of new scintillation materials that will survive the enhanced radiation environment present at the beam-beam intersections. This is a brief overview of the problem for the

C. Zorn

1993-01-01

17

Scintillating fiber optic screens: a comparison of MTF, light conversion efficiency, and emission angle with Gd2O2S:Tb screens.  

PubMed

The widespread effort in developing digital imaging systems has led to large area high pixel density photodetectors such as charge coupled devices (CCDs), amorphous silicon photodiode arrays, and complementary metal oxide semiconductor (CMOS) imagers. These photodetectors have different capabilities, characteristics, and requirements than conventional silver-halide-based film, and this fact had led to a new generation of exotic scintillators, including fiber optic screens made from scintillating glass. The scintillator performance characteristics of five different scintillating fiber optic screens and two conventional Gd2O2S:Tb screens (one 34 mg/cm2 and the other 60 mg/cm2) were measured and compared. The measurements that were made included the angular dependence of light emission relative to the normal, the modulation transfer function (MTF), and the absolute effective conversion efficiency (light photons per absorbed x-ray photon). It was found that the light emission of scintillating fiber optic screens is markedly forward peaked (depending on the sample) compared to conventional screens or Lambertian emitters. The MTFs of the five scintillating fiber optic screens measured were comparable and fell approximately midway between the two conventional screen MTFs. One of the scintillating fiber optic screens demonstrated light efficiency similar to the thick (60 mg/cm2) conventional screen, another had light output capabilities similar to the thin (34 mg/cm2) conventional screen, and the three others were less efficient than the thin screen. The non-Lambertian characteristics of the fiber optic scintillators will cause errors of up to 75% in lens efficiency calculations if a Lambertian source is assumed. The conventional screens were found to conform within about 5% of an ideal Lambertian emitter. PMID:9048369

Yu, T; Sabol, J M; Seibert, J A; Boone, J M

1997-02-01

18

Screening and Surveillance: A Guide to OSHA Standards.  

National Technical Information Service (NTIS)

The Occupational Safety and Health Administration (OSHA) receives many inquiries about the 'medical surveillance' provisions of its standards. This guide is a quick reference to help you locate and implement the screening and surveillance requirements of ...

1999-01-01

19

Cholesterol Screening: A Practical Guide to Implementation.  

ERIC Educational Resources Information Center

Dry-chemistry cholesterol analysis has made screening feasible in a variety of settings. The article provides practical tips for the implementation of mass cholesterol screening using a portable dry-chemistry analyzer and discusses issues involved in conducting effective cholesterol screening programs from start to finish. (SM)

Kingery, Paul M.

1995-01-01

20

HYDROCARBON SPILL SCREENING MODEL (HSSM) VOLUME 1: USER'S GUIDE  

EPA Science Inventory

This users guide describes the Hydrocarbon Spill Screening Model (HSSM). The model is intended for simulation of subsurface releases of light nonaqueous phase liquids (LNAPLs). The model consists of separate modules for LNAPL flow through the vadose zone, spreading in the capil...

21

Preimplantation Genetic Screening: A Practical Guide  

PubMed Central

The past several decades have seen tremendous advances in the field of medical genetics. The application of genetic technologies to the field of reproductive medicine has ushered in a new era of medicine that is likely to greatly expand in the coming years. Concurrent with an in vitro fertilization (IVF) cycle, it is now possible to obtain a cellular biopsy from a developing embryo and genetically evaluate this sample with increasing sophistication and detail. Preimplantation genetic screening (PGS) is the practice of determining the presence of aneuploidy (either too many or too few chromosomes) in a developing embryo. However, how and in whom PGS should be offered is a topic of much debate.

Brezina, Paul R.; Ke, Raymond W.; Kutteh, William H.

2013-01-01

22

Technology Screening Guide for Treatment of CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act) Soils and Sludges,  

National Technical Information Service (NTIS)

The Technology Screening Guide for Treatment of CERCLA Soils and Sludges is a guide for screening feasible alternative treatment technologies for soils and sludges at Superfund sites. The guide provides a screening methodology to identify treatment techno...

L. D. Galer

1988-01-01

23

Scintillation dosimeter arrays using air core light guides: simulation and experiment.  

PubMed

The performance of a scintillation dosimeter that uses a silvered air core light guide is examined by Monte Carlo (MC) simulations and by experiment to determine its suitability for array dosimetry in external beam radiotherapy. The air core light guide avoids the generation of the Cerenkov background that is produced in a conventional optical fibre. MC simulations using a 6 MV photon beam showed that silver thicknesses of less than 1 microm compensated for the effects of the other material components, to give the dosimeter water equivalence within 0.5%. A second dosimeter located adjacent to the primary dosimeter in any direction affected the dose measurement by less than 1.5%, when the centre-to-centre spacing was 1.3 mm or greater. When the dosimeter array is located perpendicular to the beam central axis, with a spacing of 2.5 mm, the calculated deviation from the dose deposited in water was less than 2%. When the dosimeter array is located parallel to the beam central axis with a spacing of 10 mm, the calculated dose readings deviated from water by less than 2.5%. The simulation results were confirmed with experiment for two neighbouring dosimeters and a small densely packed array. No proximity effects were measured within the experimental error of +/-1.5%. These results confirm the dosimetric accuracy of the air core dosimeter design without the need for correction factors. The dosimeter has excellent potential for use in arrays. PMID:20505222

Naseri, Pourandokht; Suchowerska, Natalka; McKenzie, David R

2010-06-21

24

Monte Carlo and Lambertian light guide models of the light output from scintillation crystals at megavoltage energies  

SciTech Connect

A new model of the light output from single-crystal scintillators in megavoltage energy x-ray beams has been developed, based on the concept of a Lambertian light guide model (LLG). This was evaluated in comparison with a Monte Carlo (MC) model of optical photon transport, previously developed and reported in the literature, which was used as a gold standard. The LLG model was developed to enable optimization of scintillator detector design. In both models the dose deposition and light propagation were decoupled, the scintillators were cuboids, split into a series of cells as a function of depth, with Lambertian side and entrance faces, and a specular exit face. The signal in a sensor placed 1 and 1000 mm beyond the exit face was calculated. Cesium iodide (CSI) crystals of 1.5 and 3 mm square cross section and 1, 5, and 10 mm depth were modeled. Both models were also used to determine detector signal and optical gain factor as a function of CsI scintillator thickness, from 2 to 10 mm. Results showed a variation in light output with position of dose deposition of a factor of up to approximately 5, for long, thin scintillators (such as 10x1.5x1.5 mm{sup 3}). For short, fat scintillators (such as 1x3x3 mm{sup 3}) the light output was more uniform with depth. MC and LLG generally agreed to within 5%. Results for a sensor distance of 1 mm showed an increase in light output the closer the light originates to the exit face, while a distance of 1000 mm showed a decrease in light output the closer the light originates to the exit face. For a sensor distance of 1 mm, the ratio of signal for a 10 mm scintillator to that for a 2 mm scintillator was 1.98, whereas for the 1000 mm distance the ratio was 3.00. The ratio of quantum efficiency (QE) between 10 and 2 mm thicknesses was 4.62. We conclude that these models may be used for detector optimization, with the light guide model suitable for parametric study.

Evans, Philip M.; Mosleh-Shirazi, M. Amin; Harris, Emma J.; Seco, Joao [Joint Physics Department, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Downs Road, Sutton, Surrey, SM2 5PT (United Kingdom)

2006-06-15

25

New process for screen cutting: water-jet guided laser  

NASA Astrophysics Data System (ADS)

Today's OLED manufacturers need high-precision, fast tools to cut the metal screens used to deposit the electroluminescent layers onto the substrate. Conventional methods -tching and dry laser cutting - are not satisfying regarding the demands of high-definition OLED displays. A new micro machining technology, the water jet guided laser - a hybrid of laser and water jet technologies that has been actively used in recent years in the electronic and semiconductor field - is now available to OLED manufacturers. This technology represents a significant improvement in screen, mask and stencil cutting, as it combines high precision and high speed. It is able to cut small apertures with totally clean edges (no dross or slag), as the water jet removes the particles and a thin water film is maintained on the material surface during the process. Because the water jet cools the material between the laser pulses, the cut material is free of any thermal stress. The water jet guided laser is also a very fast process: as an example, rectangular slots can be cut in 30 to 50 microns thick stainless steel or nickel at a rate between 25'000 and 30'000 holes per hour.

Perrottet, Delphine; Amorosi, Simone; Richerzhagen, Bernold

2005-07-01

26

[Radiation screening test for commercial food products and foodstuffs for food services using NaI (Tl) scintillation survey meter].  

PubMed

Screening tests were carried out for radioactive cesium in foods using a NaI (Tl) scintillation survey meter. The screening level was set at 250 Bq/kg, and specimens exceeding this level were scheduled to be sent to an external testing organization, which would conduct further tests using a germanium semiconductor detector. Some specimens that did not reach the screening level were also sent to the same organization. Foodstuffs used in commercial food products circulated in Chiba city were targeted, along with food services provided to schools and day care centers. In all, 495 specimens were tested; however, no specimens exceeded the screening level. The results of verification tests confirmed that no specimen exceeded the tentative regulatory limit. PMID:23676692

Kamimura, Masaru; Takanashi, Yoshimitsu; Kihara, Akiko; Tsutake, Toyoshige; Mitsui, Yoshio

2013-01-01

27

Use and imaging performance of CMOS flat panel imager with LiF/ZnS(Ag) and Gadox scintillation screens for neutron radiography  

NASA Astrophysics Data System (ADS)

In digital neutron radiography system, a thermal neutron imaging detector based on neutron-sensitive scintillating screens with CMOS(complementary metal oxide semiconductor) flat panel imager is introduced for non-destructive testing (NDT) application. Recently, large area CMOS APS (active-pixel sensor) in conjunction with scintillation films has been widely used in many digital X-ray imaging applications. Instead of typical imaging detectors such as image plates, cooled-CCD cameras and amorphous silicon flat panel detectors in combination with scintillation screens, we tried to apply a scintillator-based CMOS APS to neutron imaging detection systems for high resolution neutron radiography. In this work, two major Gd2O2S:Tb and 6LiF/ZnS:Ag scintillation screens with various thickness were fabricated by a screen printing method. These neutron converter screens consist of a dispersion of Gd2O2S:Tb and 6LiF/ZnS:Ag scintillating particles in acrylic binder. These scintillating screens coupled-CMOS flat panel imager with 25x50mm2 active area and 48?m pixel pitch was used for neutron radiography. Thermal neutron flux with 6x106n/cm2/s was utilized at the NRF facility of HANARO in KAERI. The neutron imaging characterization of the used detector was investigated in terms of relative light output, linearity and spatial resolution in detail. The experimental results of scintillating screen-based CMOS flat panel detectors demonstrate possibility of high sensitive and high spatial resolution imaging in neutron radiography system.

Cha, B. K.; kim, J. Y.; Kim, T. J.; Sim, C.; Cho, G.; Lee, D. H.; Seo, C.-W.; Jeon, S.; Huh, Y.

2011-01-01

28

Scintillation Counters  

NASA Astrophysics Data System (ADS)

Scintillators find wide use in radiation detection as the detecting medium for gamma/X-rays, and charged and neutral particles. Since the first notice in 1895 by Roentgen of the production of light by X-rays on a barium platinocyanide screen, and Thomas Edison's work over the following 2 years resulting in the discovery of calcium tungstate as a superior fluoroscopy screen, much research and experimentation have been undertaken to discover and elucidate the properties of new scintillators. Scintillators with high density and high atomic number are prized for the detection of gamma rays above 1 MeV; lower atomic number, lower-density materials find use for detecting beta particles and heavy charged particles; hydrogenous scintillators find use in fast-neutron detection; and boron-, lithium-, and gadolinium-containing scintillators are used for slow-neutron detection. This chapter provides the practitioner with an overview of the general characteristics of scintillators, including the variation of probability of interaction with density and atomic number, the characteristics of the light pulse, a list and characteristics of commonly available scintillators and their approximate cost, and recommendations regarding the choice of material for a few specific applications. This chapter does not pretend to present an exhaustive list of scintillators and applications.

Bell, Zane W.

29

The design of an active pixel sensor test structure optimised for the read out of scintillator screens  

NASA Astrophysics Data System (ADS)

Indirect detection of X-rays using a scintillator coupled to a Solid-state sensor is an application where the CMOS Active Pixel Sensor (APS) can offer improved performance compared with conventional charge coupled device (CCD) based systems. The main advantages that CMOS sensors offer are reduced susceptibility to radiation damage, lower power consumption and increased on chip functionality. We describe the operation of a basic photodiode type pixel and explain how the read-out and sensing arrangement can be optimised for indirect X-ray detection in digital radiography applications. The optimised pixel is designed to have a narrow-band response to visible light generated by a scintillator screen, while at the same time suppressing signal from direct X-ray interaction. We outline a programme that has recently begun at Brunel University and e2v technologies to design, fabricate, and characterise variants of these pixel structures to perform a parametric study of CMOS imager performance.

Greig, Tom; Castelli, Chris; Holland, Andrew; Burt, David

2007-04-01

30

Fabrication and imaging characterization of high sensitive CsI(Tl) and Gd 2O 2S(Tb) scintillator screens for X-ray imaging detectors  

Microsoft Academic Search

Indirect-detection methods consisted of an X-ray converter and photodiode arrays are more widely used in medical diagnosis and industrial fields. Two major scintillation materials such as terbium-doped gadolinium oxysulfide(Gd2O2S:Tb, Gadox) and thallium-doped cesium iodide(CsI:Tl) are commonly used. In this work, Gadox screens were manufactured by particle in binder (PIB) layer method and CsI:Tl scintillator films with columnar structure were also

Bo Kyung Cha; Jong Yul Kim; Tae Joo Kim; Cheulmuu Sim; Gyuseong Cho

2010-01-01

31

X-Ray Image Detector Based on Light Guides and Scintillators  

Microsoft Academic Search

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

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

2009-01-01

32

Infection and blood transfusion: a guide to donor screening  

Microsoft Academic Search

In recent years, blood-component therapy has become more accessible in veterinary practice. As with human medicine, care must be taken to minimize the risk of disease transmission from donor to recipient. Determining the appropriate diseases to screen for is complicated by regional variations in disease incidence, the existence of chronic carrier states for some diseases, the difficulty in screening-test selection,

Nyssa J Reine

2004-01-01

33

Experimental validation of Monte Carlo (MANTIS) simulated x-ray response of columnar CsI scintillator screens  

SciTech Connect

Purpose: MANTIS is a Monte Carlo code developed for the detailed simulation of columnar CsI scintillator screens in x-ray imaging systems. Validation of this code is needed to provide a reliable and valuable tool for system optimization and accurate reconstructions for a variety of x-ray applications. Whereas previous validation efforts have focused on matching of summary statistics, in this work the authors examine the complete point response function (PRF) of the detector system in addition to relative light output values. Methods: Relative light output values and high-resolution PRFs have been experimentally measured with a custom setup. A corresponding set of simulated light output values and PRFs have also been produced, where detailed knowledge of the experimental setup and CsI:Tl screen structures are accounted for in the simulations. Four different screens were investigated with different thicknesses, column tilt angles, and substrate types. A quantitative comparison between the experimental and simulated PRFs was performed for four different incidence angles (0 deg., 15 deg., 30 deg., and 45 deg.) and two different x-ray spectra (40 and 70 kVp). The figure of merit (FOM) used measures the normalized differences between the simulated and experimental data averaged over a region of interest. Results: Experimental relative light output values ranged from 1.456 to 1.650 and were in approximate agreement for aluminum substrates, but poor agreement for graphite substrates. The FOMs for all screen types, incidence angles, and energies ranged from 0.1929 to 0.4775. To put these FOMs in context, the same FOM was computed for 2D symmetric Gaussians fit to the same experimental data. These FOMs ranged from 0.2068 to 0.8029. Our analysis demonstrates that MANTIS reproduces experimental PRFs with higher accuracy than a symmetric 2D Gaussian fit to the experimental data in the majority of cases. Examination of the spatial distribution of differences between the PRFs shows that the main reason for errors between MANTIS and the experimental data is that MANTIS-generated PRFs are sharper than the experimental PRFs. Conclusions: The experimental validation of MANTIS performed in this study demonstrates that MANTIS is able to reliably predict experimental PRFs, especially for thinner screens, and can reproduce the highly asymmetric shape seen in the experimental data. As a result, optimizations and reconstructions carried out using MANTIS should yield results indicative of actual detector performance. Better characterization of screen properties is necessary to reconcile the simulated light output values with experimental data.

Freed, Melanie; Miller, Stuart; Tang, Katherine; Badano, Aldo [CDRH/NIBIB Laboratory for the Assessment of Medical Imaging Systems, Division of Imaging and Applied Mathematics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993-0002 and University of Maryland, College Park, Maryland 20742 (United States); RMD, Inc., 44 Hunt Street, Watertown, Massachusetts 02472 (United States); CDRH/NIBIB Laboratory for the Assessment of Medical Imaging Systems, Division of Imaging and Applied Mathematics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993-0002 (United States)

2009-11-15

34

Alcohol Screening and Brief Intervention for Youth: A Practitioner's Guide.  

National Technical Information Service (NTIS)

With this Guide, the National Institute on Alcohol Abuse and Alcoholism (NIAAA) introduces a simple, quick, empirically derived tool for identifying youth at risk for alcohol-related problems. If you manage the health and well-being of children and adoles...

2011-01-01

35

Hazard screening application guide. Safety Analysis Report Update Program  

SciTech Connect

The basic purpose of hazard screening is to group precesses, facilities, and proposed modifications according to the magnitude of their hazards so as to determine the need for and extent of follow on safety analysis. A hazard is defined as a material, energy source, or operation that has the potential to cause injury or illness in human beings. The purpose of this document is to give guidance and provide standard methods for performing hazard screening. Hazard screening is applied to new and existing facilities and processes as well as to proposed modifications to existing facilities and processes. The hazard screening process evaluates an identified hazards in terms of the effects on people, both on-site and off-site. The process uses bounding analyses with no credit given for mitigation of an accident with the exception of certain containers meeting DOT specifications. The process is restricted to human safety issues only. Environmental effects are addressed by the environmental program. Interfaces with environmental organizations will be established in order to share information.

none,

1992-06-01

36

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

37

Shared decision-making about colorectal cancer screening: A conceptual framework to guide research  

PubMed Central

Objective To develop a conceptual framework to guide research on shared decision-making about colorectal cancer (CRC) screening among persons at average risk and their providers. Methods Based upon a comprehensive review of empirical literature and relevant theories, a conceptual framework was developed that incorporated patient characteristics, cultural beliefs, provider/health care system, health beliefs/stage of adoption, and shared decision-making between patients and providers that may predict behavior. Relationships among concepts in the framework, shared decision-making process and outcomes, and CRC screening behavior were proposed. Directions for future research were presented. Results Many of the concepts in the proposed framework have been examined in prior research. However, these elements have not been combined previously to explain shared decision-making about CRC screening. Conclusion Research is needed to test the proposed relationships and hypotheses and to refine the framework. Practice Implications Findings from future research guided by the proposed framework may inform clinical practice to facilitate shared decision-making about CRC screening.

Christy, Shannon M.; Rawl, Susan M.

2013-01-01

38

Simulating the effects of scintillation on transionospheric signals with a two-way phase screen constructed from ALTAIR phase-derived TEC  

NASA Astrophysics Data System (ADS)

Severe scintillation on transionospheric radio signals caused by small-scale plasma irregularities can greatly disrupt wideband communication, surveillance, and navigation systems. Development of techniques to mitigate the effects of scintillation requires accurate characterization of the ionospheric propagation channel. To achieve this goal, multiple campaigns were conducted as part of the joint U.S. -UK Wideband Ionospheric Distortion Experiment to obtain ionospheric signatures from various instruments located on Kwajalein Atoll. We use tracking data from the VHF/UHF Advanced Research Project Agency Long-Range Tracking and Instrumentation Radar for overflights of passive calibration spheres in low-Earth orbit to demonstrate the validity of a one-dimensional (1-D) phase screen model to represent the propagation channel through a disturbed ionosphere. The 1-D phase screen is constructed from radar phase-derived estimates of the total electron content. We present a detailed comparison of simulated radar cross section after propagation through the phase screen with observed radar returns under both disturbed and quiet ionospheric conditions. Successful reproduction of radar amplitude enhancements and fades adds to our understanding of small-scale plasma irregularities and moves us toward our goal of providing precise predictions of radar system performance. Doing so will allow for the development of better mitigation/compensation algorithms for detrimental ionospheric effects. Result from this study also provide an assessment of the tools required for incorporating in situ density measurements along with phase screen theory into situational awareness products to offer an accurate nowcast/forecast of system impacts to users in the communication, navigation, and surveillance communities.

Caton, R. G.; Carrano, C. S.; Alcala, C. M.; Groves, K. M.; Beach, T.; Sponseller, D.

2009-02-01

39

Ionospheric scintillation  

Microsoft Academic Search

Available observations of ionospheric scintillation are analyzed to evaluate the adequacy of existing models used for the interpretation of scintillation data. The theoretical models are reviewed and the frequency and propagation geometry dependences predicted by the models are compared with the observations. The models were used to construct scintillation occurrence distribution functions which show that scintillation phenomena significantly affect the

R. K. Crane

1977-01-01

40

A 1,536-well [(35)S]GTPgammaS scintillation proximity binding assay for ultra-high-throughput screening of an orphan galphai-coupled GPCR.  

PubMed

Members of the superfamily of seven transmembrane receptors, known as G protein-coupled receptors (GPCRs), are important targets for many therapeutic areas in drug discovery. A homogeneous guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) scintillation proximity assay (SPA) binding assay targeting a Galphai-coupled GPCR recombinantly expressed in membranes of Chinese hamster ovary (CHO) cells was developed and miniaturized into 1,536-well plate format. The primary ultra-high-throughput screen of the entire compound collection was accomplished on the Kalypsys (San Diego, CA) robotic platform at a concentration of 8 muM using the 1,536-well [(35)S]GTPgammaS SPA binding functional assay. The signal-to-noise ratio of the primary screen was approximately 2.1-fold, and the plate coefficient of variation for the compound field was approximately 11%. The hit rate from the primary screen for receptor agonists at >35% activity was approximately 0.3%. Primary hits were cherry-picked, confirmed in triplicate, counterscreened against untransfected CHO cell membranes, and further analyzed in a cyclic AMP functional assay, resulting in 34 leads for optimization. PMID:18537464

Johnson, Eric N; Shi, Xiaoqing; Cassaday, Jason; Ferrer, Marc; Strulovici, Berta; Kunapuli, Priya

2008-06-01

41

Measurement of transmission efficiency for 400 MeV proton beam through collimator at Fermilab MuCool Test Area using Chromox-6 scintillation screen.  

PubMed

The MuCool Test Area (MTA) at Fermilab is a facility to develop the technology required for ionization cooling for a future Muon Collider and?or Neutrino Factory. As part of this research program, feasibility studies of various types of RF cavities in a high magnetic field environment are in progress. As a unique approach, we have tested a RF cavity filled with a high pressure hydrogen gas with a 400 MeV proton beam in an external magnetic field (B = 3 T). Quantitative information about the number of protons passing through this cavity is an essential requirement of the beam test. The MTA is a flammable gas (hydrogen) hazard zone. Due to safety reasons, no active (energized) beam diagnostic instrument can be used. Moreover, when the magnetic field is on, current transformers (toroids) used for beam intensity measurements do not work due to the saturation of the ferrite material of the transformer. Based on these requirements, we have developed a passive beam diagnostic instrumentation using a combination of a Chromox-6 scintillation screen and CCD camera. This paper describes details of the beam profile and position obtained from the CCD image with B = 0 T and B = 3 T, and for high and low intensity proton beams. A comparison is made with beam size obtained from multi-wires detector. Beam transmission efficiency through a collimator with a 4 mm diameter hole is measured by the toroids and CCD image of the scintillation screen. Results show that the transmission efficiency estimated from the CCD image is consistent with the toroid measurement, which enables us to monitor the beam transmission efficiency even in a high magnetic field environment. PMID:23822337

Jana, M R; Chung, M; Freemire, B; Hanlet, P; Leonova, M; Moretti, A; Palmer, M; Schwarz, T; Tollestrup, A; Torun, Y; Yonehara, K

2013-06-01

42

Measurement of transmission efficiency for 400 MeV proton beam through collimator at Fermilab MuCool Test Area using Chromox-6 scintillation screen  

SciTech Connect

The MuCool Test Area (MTA) at Fermilab is a facility to develop the technology required for ionization cooling for a future Muon Collider and/or Neutrino Factory. As part of this research program, feasibility studies of various types of RF cavities in a high magnetic field environment are in progress. As a unique approach, we have tested a RF cavity filled with a high pressure hydrogen gas with a 400 MeV proton beam in an external magnetic field (B = 3 T). Quantitative information about the number of protons passing through this cavity is an essential requirement of the beam test. The MTA is a flammable gas (hydrogen) hazard zone. Due to safety reasons, no active (energized) beam diagnostic instrument can be used. Moreover, when the magnetic field is on, current transformers (toroids) used for beam intensity measurements do not work due to the saturation of the ferrite material of the transformer. Based on these requirements, we have developed a passive beam diagnostic instrumentation using a combination of a Chromox-6 scintillation screen and CCD camera. This paper describes details of the beam profile and position obtained from the CCD image with B = 0 T and B = 3 T, and for high and low intensity proton beams. A comparison is made with beam size obtained from multi-wires detector. Beam transmission efficiency through a collimator with a 4 mm diameter hole is measured by the toroids and CCD image of the scintillation screen. Results show that the transmission efficiency estimated from the CCD image is consistent with the toroid measurement, which enables us to monitor the beam transmission efficiency even in a high magnetic field environment.

Jana, M. R.; Chung, M.; Leonova, M.; Moretti, A.; Palmer, M.; Schwarz, T.; Tollestrup, A.; Yonehara, K. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Freemire, B.; Hanlet, P.; Torun, Y. [Illinois Institute of Technology, Chicago, Illinois 60616 (United States)

2013-06-15

43

Flavonoids and sesquiterpenoids, constituents from Eupatorium capillifolium , found in a screening study guided by cell growth inhibitory activity  

Microsoft Academic Search

Four flavonoids (1-4) and eight sesquiterpenoids (5–12) were isolated from the MeOH extract of Eupatorium capillifolium leaves in a screening study guided by cell growth inhibitory activity. Among the isolated compounds, 5–7 and 11 showed potent inhibitory effects on the growth of HeLa cells.

Samir Kumar Sadhu; Kaori Hirata; Xiaofan Li; Takashi Ohtsuki; Takashi Koyano; Srisomporn Preeprame; Thaworn Kowithayakorn; Masami Ishibashi

2006-01-01

44

Using adverse outcome pathway analysis to guide development of high-throughput screening assays for thyroid-disruptors  

EPA Science Inventory

Using Adverse Outcome Pathway Analysis to Guide Development of High-Throughput Screening Assays for Thyroid-Disruptors Katie B. Paul1,2, Joan M. Hedge2, Daniel M. Rotroff4, Kevin M. Crofton4, Michael W. Hornung3, Steven O. Simmons2 1Oak Ridge Institute for Science Education Post...

45

Peptide ligands for pro-survival protein Bfl-1 from computationally guided library screening  

PubMed Central

Pro-survival members of the Bcl-2 protein family inhibit cell death by binding short helical BH3 motifs in pro-apoptotic proteins. Mammalian pro-survival proteins Bcl-xL, Bcl-2, Bcl-w, Mcl-1 and Bfl-1 bind with varying affinities and specificities to native BH3 motifs, engineered peptides and small molecules. Biophysical studies have determined interaction patterns for these proteins, particularly for the most-studied family members Bcl-xL and Mcl-1. Bfl-1 is a pro-survival protein implicated in preventing apoptosis in leukemia, lymphoma and melanoma. Although Bfl-1 is a promising therapeutic target, relatively little is known about its binding preferences. We explored the binding of Bfl-1 to BH3-like peptides by screening a peptide library that was designed to sample a high degree of relevant sequence diversity. Screening using yeast-surface display led to several novel high-affinity Bfl-1 binders and to thousands of putative binders identified through deep sequencing. Further screening for specificity led to identification of a peptide that bound to Bfl-1 with Kd < 1 nM and very slow dissociation from Bfl-1 compared to other pro-survival Bcl-2 family members. A point mutation in this sequence gave a peptide with ~50 nM affinity for Bfl-1 that was selective for Bfl-1 in equilibrium binding assays. Analysis of engineered Bfl-1 binders deepens our understanding of how the binding profiles of pro-survival proteins differ, and may guide the development of targeted Bfl-1 inhibitors.

Dutta, Sanjib; Chen, T. Scott; Keating, Amy E.

2013-01-01

46

Imaging performance of a thin Lu2O3:Eu nanophosphor scintillating screen coupled to a high resolution CMOS sensor under X-ray radiographic conditions: comparison with Gd2O2S:Eu conventional phosphor screen  

NASA Astrophysics Data System (ADS)

The purpose of the present study was to experimentally evaluate the imaging characteristics of the Lu2O3:Eu nanophosphor thin screen coupled to a high resolution CMOS sensor under radiographic conditions. Parameters such as the Modulation Transfer Function (MTF), the Normalized Noise Power Spectrum (NNPS) and the Detective Quantum Efficiency (DQE) were investigated at 70 kVp under three exposure levels (20 mAs, 63 mAs and 90 mAs). Since Lu2O3:Eu emits light in the red wavelength range, the imaging characteristics of a 33.3 mg/cm2 Gd2O2S:Eu conventional phosphor screen were also evaluated for comparison purposes. The Lu2O3:Eu nanophosphor powder was produced by the combustion synthesis, using urea as fuel. A scintillating screen of 30.2 mg/cm2 was prepared by sedimentation of the nanophosphor powder on a fused silica substrate. The CMOS/Lu2O3:Eu detector`s imaging characteristics were evaluated using an experimental method proposed by the International Electrotechnical Commission (IEC) guidelines. It was found that the CMOS/Lu2O3:Eu nanophosphor system has higher MTF values compared to the CMOS/Gd2O2S:Eu sensor/screen combination in the whole frequency range examined. For low frequencies (0 to 2 cycles/mm) NNPS values of the CMOS/Gd2O2S:Eu system were found 90% higher compared to the NNPS values of the CMOS/Lu2O3:Eu nanophosphor system, whereas from medium to high frequencies (2 to 13 cycles/mm) were found 40% higher. In contrast with the CMOS/ Gd2O2S:Eu system, CMOS/Lu2O3:Eu nanophosphor system appears to retain high DQE values in the whole frequency range examined. Our results indicate that Lu2O3:Eu nanophosphor is a promising scintillator for further research in digital X-ray radiography.

Seferis, I.; Michail, C.; Valais, I.; Zeler, J.; Liaparinos, P.; Kalyvas, N.; Fountos, G.; Zych, E.; Kandarakis, I.; Panayiotakis, G.

2014-03-01

47

Ceramic Scintillators  

NASA Astrophysics Data System (ADS)

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

Greskovich, C.; Duclos, S.

1997-08-01

48

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

49

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

50

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

51

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

52

Synthesis of potent dishevelled PDZ domain inhibitors guided by virtual screening and NMR studies.  

PubMed

Dishevelled (Dvl) PDZ domains transduce Wnt signals from the membrane-bound receptor Frizzled to the downstream. As abnormal Wnt signaling has been implicated in tumorigenesis, the Dvl PDZ domain is a potential target for small-molecule inhibitors that block Wnt signaling at the Dvl level. We expanded our in silico search to examine the chemical space near previously developed PDZ binders and identified nine additional compounds bind to the Dvl PDZ. We then performed a quantitative structure-activity relationship (QSAR) analysis of these compounds and combined these results with structural studies of the PDZ domain in complex with the compounds to design and synthesize a group of new, further optimized compounds. Two rounds of synthesis and testing yielded a total of six compounds that have greatly improved binding affinity to the Dvl PDZ domain and most potent ones competitively displace Dapper peptide from the PDZ domain. In addition to providing more potent Dvl PDZ domain inhibitors, this study demonstrates that virtual screening and structural studies can be powerful tools in guiding the chemical synthesis hit-to-lead optimization stage during the drug discovery process. PMID:22172211

Shan, Jufang; Zhang, Xinxin; Bao, Ju; Cassell, Robert; Zheng, Jie J

2012-04-01

53

Simulating the effects of scintillation on transionospheric signals with a two-way phase screen constructed from ALTAIR phase-derived TEC  

Microsoft Academic Search

Severe scintillation on transionospheric radio signals caused by small-scale plasma irregularities can greatly disrupt wideband communication, surveillance, and navigation systems. Development of techniques to mitigate the effects of scintillation requires accurate characterization of the ionospheric propagation channel. To achieve this goal, multiple campaigns were conducted as part of the joint U.S. -UK Wideband Ionospheric Distortion Experiment to obtain ionospheric signatures

R. G. Caton; C. S. Carrano; C. M. Alcala; K. M. Groves; T. Beach; D. Sponseller

2009-01-01

54

Validity of cognitive screens for HIV-associated neurocognitive disorder: a systematic review and an informed screen selection guide.  

PubMed

Various screening tools have been proposed to identify HIV-Associated Neurocognitive Disorder (HAND). However, there has been no systematic review of their strengths and weaknesses in detecting HAND when compared to gold standard neuropsychological testing. Thirty-five studies assessing HAND screens that were conducted in the era of combination antiretroviral therapy were retrieved using standard search procedures. Of those, 19 (54 %) compared their screen to standard neuropsychological testing. Studies were characterised by a wide variation in criterion validity primarily due to non-standard definition of neurocognitive impairment, and to the demographic and clinical heterogeneity of samples. Assessment of construct validity was lacking, and longitudinal useability was not established. To address these limitations, the current review proposed a summary of the most sensitive and specific studies (>70 %), as well as providing explicit caution regarding their weaknesses, and recommendations for their use in HIV primary care settings. PMID:24072534

Kamminga, Jody; Cysique, Lucette A; Lu, Grace; Batchelor, Jennifer; Brew, Bruce J

2013-12-01

55

Screening of Protein-Protein Interaction Modulators via Sulfo-Click Kinetic Target-Guided Synthesis  

PubMed Central

Kinetic Target-Guided Synthesis (TGS) and in situ click chemistry are among unconventional discovery strategies having the potential to streamline the development of protein-protein interaction modulators (PPIMs). In kinetic TGS and in situ click chemistry, the target is directly involved in the assembly of its own potent, bidentate ligand from a pool of reactive fragments. Herein, we report the use and validation of kinetic TGS based on the sulfo-click reaction between thio acids and sulfonyl azides as a screening and synthesis platform for the identification of high-quality PPIMs. Starting from a randomly designed library consisting of 9 thio acids and 9 sulfonyl azides leading to 81 potential acylsulfonamides, the target protein, Bcl-XL selectively assembled four PPIMs, acylsulfonamides SZ4TA2, SZ7TA2, SZ9TA1, and SZ9TA5, which have been shown to modulate Bcl-XL/BH3 interactions. To further investigate the Bcl-XL templation effect, control experiments were carried out using two mutants of Bcl-XL. In one mutant, phenylalanine Phe131 and aspartic acid Asp133, which are critical for the BH3 domain binding, have been substituted by alanines, while arginine Arg139, a residue identified to play a crucial role in the binding of ABT-737, a BH3 mimetic, has been replaced by an alanine in the other mutant. Incubation of these mutants with the reactive fragments and subsequent LC/MS-SIM analysis confirmed that these building block combinations yield the corresponding acylsulfonamides at the BH3 binding site, the actual “hot spot” of Bcl-XL. These results validate kinetic TGS using the sulfo-click reaction as a valuable tool for the straightforward identification of high-quality PPIMs.

Kulkarni, Sameer S.; Hu, Xiangdong; Doi, Kenichiro; Wang, Hong-Gang

2011-01-01

56

Screening for Usher Syndrome: A Hands-On Guide for School Nurses.  

ERIC Educational Resources Information Center

This manual was written specifically to help school nurses conduct screenings for Usher syndrome, a genetic condition that involves deafness or hearing loss and the progressive loss of vision. It provides information on the step-by-step process of how to conduct a screening, the actual forms needed for a screening, and resources for referring…

Houghton, Joan; Coonts, Teresa; Jordan, Beth; Schafer, Jacqueline, Ed.

57

TAKING IT TO THE PEWS: A CBPR-GUIDED HIV AWARENESS AND SCREENING PROJECT WITH BLACK CHURCHES  

PubMed Central

Utilizing a community-based participatory research (CBPR) approach is a potentially effective strategy for exploring the development, implementation, and evaluation of HIV interventions in African American churches. This CBPR-guided study describes a church-based HIV awareness and screening intervention (Taking It to the Pews [TIPS]) that fully involved African American church leaders in all phases of the research project. Findings from the implementation and evaluation phases indicated that church leaders delivered TIPS Tool Kit activities on an ongoing basis (about twice a month) over a 9-month period. TIPS church members were highly exposed to TIPS activities (e.g., 91% reported receiving HIV educational brochures, 84% heard a sermon about HIV). Most (87%) believed that the church should talk about HIV, and 77% believed that the church should offer HIV screening. These findings suggest that implementing an HIV intervention in Black church settings is achievable, particularly when a CBPR approach is used.

Berkley-Patton, Jannette; Bowe-Thompson, Carole; Bradley-Ewing, Andrea; Hawes, Starlyn; Moore, Erin; Williams, Eric; Martinez, David; Goggin, Kathy

2014-01-01

58

Use of the Nutrition Screening Initiative to Target and Guide Nutrition Education Efforts in Nevada  

Microsoft Academic Search

The goal of the Nutrition Screening Initiative (NSI) is to identify individuals who are at high risk of poor nutritional status - for whom more in-depth assessment\\/intervention is indicated. Implementation of the NSI in Nevada included screening elderly who participate in Senior Nutrition Programs and providing nutrition education to elderly who were at risk for poor nutritional status. Participants of

J. Benedict; D. Wilson; G. Snow; P. Tyler; V. Remig; M. Dodds; C. Leontos; M. Read

1995-01-01

59

Metal Finishing Facility Risk Screening Tool (MFFRST): Technical Documentation and User's Guide (on CD-ROM).  

National Technical Information Service (NTIS)

The Metal Finishing Facility Risk Screening Tool (MFFRST), is a user-friendly tool that enables anyone to perform a screening characterization of health risks to workers and neighbors of metal finishing processes, was developed by the U.S. Environmental P...

2001-01-01

60

IRon Overload ScreeNing tool (IRON): Development of a tool to guide screening in primary care  

PubMed Central

Iron overload is associated with significant morbidity and mortality yet is easily treated. The objective of this study was to create a tool that could be easily adapted to clinical practice that indicates the likelihood of a patient having undetected iron overload. We used the National Health and Nutrition Examination Survey (NHANES) 1999–2002 for US adults aged 20 years and older to build a model (unweighted n=8,779). We chose potential variables for inclusion that could be gathered by self-report or measured without laboratory data and were suggested by past literature on hemochromatosis and iron overload. We computed logistic regressions to create the scores by initially evaluating the variables’ relationship with elevated ferritin and elevated transferrin saturation and then using odds ratios to correspond to scores. The resulting score on the IRon Overload ScreeNing Tool (IRON) was then validated with data on 13,844 adults in the NHANES III, 1988-94. Predictors in the final tool were age, gender, previous diagnoses of liver condition, osteoporosis or thyroid disease. The IRON score yielded an area under the curve (AUC) in the NHANES 1999-02 of 0.720 and an AUC of 0.685 in the NHANES III validation sample. The IRON score is a tool to assist in identification of patients with iron overload that has several qualities that make it attractive for use in clinical practice with an undifferentiated patient population including brevity, easily collected information and predictive ability comparable to other tools that help in directing screening.

Mainous, Arch G.; Diaz, Vanessa A.; Everett, Charles J.; Knoll, Michele E.; Hulihan, Mary M.; Grant, Althea M.; McLaren, Christine E.; McLaren, Gordon D.

2013-01-01

61

Genome-wide recessive genetic screening in mammalian cells with a lentiviral CRISPR-guide RNA library.  

PubMed

Identification of genes influencing a phenotype of interest is frequently achieved through genetic screening by RNA interference (RNAi) or knockouts. However, RNAi may only achieve partial depletion of gene activity, and knockout-based screens are difficult in diploid mammalian cells. Here we took advantage of the efficiency and high throughput of genome editing based on type II, clustered, regularly interspaced, short palindromic repeats (CRISPR)-CRISPR-associated (Cas) systems to introduce genome-wide targeted mutations in mouse embryonic stem cells (ESCs). We designed 87,897 guide RNAs (gRNAs) targeting 19,150 mouse protein-coding genes and used a lentiviral vector to express these gRNAs in ESCs that constitutively express Cas9. Screening the resulting ESC mutant libraries for resistance to either Clostridium septicum alpha-toxin or 6-thioguanine identified 27 known and 4 previously unknown genes implicated in these phenotypes. Our results demonstrate the potential for efficient loss-of-function screening using the CRISPR-Cas9 system. PMID:24535568

Koike-Yusa, Hiroko; Li, Yilong; Tan, E-Pien; Velasco-Herrera, Martin Del Castillo; Yusa, Kosuke

2014-03-01

62

Plastic scintillation dosimetry: Optimal selection of scintillating fibers and scintillators  

Microsoft Academic Search

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

Louis Archambault; Jean Arsenault; Luc Gingras; A. Sam Beddar; Rene? Roy; Luc Beaulieu

2005-01-01

63

A GUIDE TO THE ORNL ECOTOXICOLOGICAL SCREENING BENCHMARKS: BACKGROUND, DEVELOPMENT, AND APPLICATION  

Microsoft Academic Search

ACKNOWLEDGMENTS Funding for development of this guide was provided by the U.S. Department of Energy, Office of EnvironmentalPolicy and Assistance, Air, Water, and Radiation Division (EH-412; Stephen Domotor, Technical Project Manager). We are grateful for the multiple respondents to our request for information concerning,field examples,of use and acceptance,of the ORNL benchmarks. This guide benefitted from reviews by Stephen Domotor (EH-412),

Bradley E. Sample; Glenn W. Suter II; Rebecca A. Efroymson; Daniel S. Jones

64

ICSN - Designing Print Materials: A Communications Guide for Breast Cancer Screening  

Cancer.gov

Skip to Main Content Search International Cancer Screening Network Sponsored by the National Cancer Institute Home | About ICSN | Collaborative Projects | Meetings | Cancer Sites | Publications | Contact Us Publications: Search the Database | Communications

65

A computational screen for mammalian pseudouridylation guide H\\/ACA RNAs  

Microsoft Academic Search

The box H\\/ACA RNA gene family is one of the largest non-protein-coding gene families in eukaryotes and archaea. Recently, we developed snoGPS, a computational screening program for H\\/ACA snoRNAs, and applied it to Saccharomyces cerevisiae .W e report here results of extending our method to screen for H\\/ACA RNAs in multiple large genomes of related species, and apply it to

PETER SCHATTNER; SERGIO BARBERAN-SOLER; TODD M. LOWE

2006-01-01

66

METAL FINISHING FACILITY RISK SCREENING TOOL (MFFRST): TECHNICAL DOCUMENTATION AND USER'S GUIDE  

EPA Science Inventory

The model MFFRST, short for Metal Finishing Facility Risk Screening Tool, is a user-friendly pc-based computer tool which allows an individual to evaluate the potential exposures and health risks to workers and nearby residents from emissions from individual metal finishing facil...

67

EPSDT (Early and Periodic Screening, Diagnosis, and Treatment) - A Guide for Educational Programs.  

National Technical Information Service (NTIS)

The Early and Periodic Screening, Diagnosis, and Treatment (EPSDT) program is the preventive health component of Medicaid which serves the 0-21 year old population. Although created in 1967, EPSDT has never reached the full universe of eligible children a...

S. Leeds R. Heneson-Walling J. Shwab

1980-01-01

68

Walkthrough screening evaluation field guide. Natural phenomena hazards at Department of Energy facilities: Revision 2  

SciTech Connect

The US Department of Energy (DOE) has a large inventory of existing facilities. Many of these facilities were not designed and constructed to current natural phenomena hazard (NPH) criteria. The NPH events include earthquakes, extreme winds and tornadoes, and floods. DOE Order 5480.28 establishes policy and requirements for NPH mitigation for DOE facilities. DOE is conducting a multiyear project to develop evaluation guidelines for assessing the condition and determining the need for upgrades at DOE facilities. One element of the NPH evaluation guidelines` development involves the existing systems and components at DOE facilities. This effort is described in detail in a cited reference. In the interim period prior to availability of the final guidelines, DOE facilities are encouraged to implement an NPH walk through screening evaluation process by which systems and components that need attention can be rapidly identified. Guidelines for conducting the walk through screening evaluations are contained herein. The result of the NPH walk through screening evaluation should be a prioritized list of systems and components that need further action. Simple and inexpensive fixes for items identified in the walk through as marginal or inadequate should be implemented without further study. By implementing an NPH walk through screening evaluation, DOE facilities may realize significant reduction in risk from NPH in the short term.

Eder, S.J. [EQE Engineering Consultants, San Francisco, CA (United States); Eli, M.W. [Lawrence Livermore National Lab., CA (United States); Salmon, M.W. [EQE Engineering Consultants, Irvine, CA (United States)

1993-11-01

69

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

70

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

71

Conformation Guides Molecular Efficacy in Docking Screens of Activated ?-2 Adrenergic G Protein Coupled Receptor  

PubMed Central

A prospective, large library virtual screen against an activated ?2-adrenergic receptor (?2AR) structure returned potent agonists to the exclusion of inverse-agonists, providing the first complement to the previous virtual screening campaigns against inverse-agonist-bound G protein coupled receptor (GPCR) structures, which predicted only inverse-agonists. In addition, two hits recapitulated the signaling profile of the co-crystal ligand with respect to the G protein and arrestin mediated signaling. This functional fidelity has important implications in drug design, as the ability to predict ligands with predefined signaling properties is highly desirable. However, the agonist-bound state provides an uncertain template for modeling the activated conformation of other GPCRs, as a dopamine D2 receptor (DRD2) activated model templated on the activated ?2AR structure returned few hits of only marginal potency.

2013-01-01

72

Conformation guides molecular efficacy in docking screens of activated ?-2 adrenergic G protein coupled receptor.  

PubMed

A prospective, large library virtual screen against an activated ?2-adrenergic receptor (?2AR) structure returned potent agonists to the exclusion of inverse-agonists, providing the first complement to the previous virtual screening campaigns against inverse-agonist-bound G protein coupled receptor (GPCR) structures, which predicted only inverse-agonists. In addition, two hits recapitulated the signaling profile of the co-crystal ligand with respect to the G protein and arrestin mediated signaling. This functional fidelity has important implications in drug design, as the ability to predict ligands with predefined signaling properties is highly desirable. However, the agonist-bound state provides an uncertain template for modeling the activated conformation of other GPCRs, as a dopamine D2 receptor (DRD2) activated model templated on the activated ?2AR structure returned few hits of only marginal potency. PMID:23485065

Weiss, Dahlia R; Ahn, SeungKirl; Sassano, Maria F; Kleist, Andrew; Zhu, Xiao; Strachan, Ryan; Roth, Bryan L; Lefkowitz, Robert J; Shoichet, Brian K

2013-05-17

73

GPS and ionospheric scintillations  

Microsoft Academic Search

Ionospheric scintillations are one of the earliest known effects of space weather. Caused by ionization density irregularities, scintillating signals change phase unexpectedly and vary rapidly in amplitude. GPS signals are vulnerable to ionospheric irregularities and scintillate with amplitude variations exceeding 20 dB. GPS is a weak signal system and scintillations can interrupt or degrade GPS receiver operation. For individual signals,

P. M. Kintner; B. M. Ledvina; E. R. de Paula

2007-01-01

74

Human genetics in rheumatoid arthritis guides a high-throughput drug screen of the CD40 signaling pathway.  

PubMed

Although genetic and non-genetic studies in mouse and human implicate the CD40 pathway in rheumatoid arthritis (RA), there are no approved drugs that inhibit CD40 signaling for clinical care in RA or any other disease. Here, we sought to understand the biological consequences of a CD40 risk variant in RA discovered by a previous genome-wide association study (GWAS) and to perform a high-throughput drug screen for modulators of CD40 signaling based on human genetic findings. First, we fine-map the CD40 risk locus in 7,222 seropositive RA patients and 15,870 controls, together with deep sequencing of CD40 coding exons in 500 RA cases and 650 controls, to identify a single SNP that explains the entire signal of association (rs4810485, P?=?1.4×10(-9)). Second, we demonstrate that subjects homozygous for the RA risk allele have ?33% more CD40 on the surface of primary human CD19+ B lymphocytes than subjects homozygous for the non-risk allele (P?=?10(-9)), a finding corroborated by expression quantitative trait loci (eQTL) analysis in peripheral blood mononuclear cells from 1,469 healthy control individuals. Third, we use retroviral shRNA infection to perturb the amount of CD40 on the surface of a human B lymphocyte cell line (BL2) and observe a direct correlation between amount of CD40 protein and phosphorylation of RelA (p65), a subunit of the NF-?B transcription factor. Finally, we develop a high-throughput NF-?B luciferase reporter assay in BL2 cells activated with trimerized CD40 ligand (tCD40L) and conduct an HTS of 1,982 chemical compounds and FDA-approved drugs. After a series of counter-screens and testing in primary human CD19+ B cells, we identify 2 novel chemical inhibitors not previously implicated in inflammation or CD40-mediated NF-?B signaling. Our study demonstrates proof-of-concept that human genetics can be used to guide the development of phenotype-based, high-throughput small-molecule screens to identify potential novel therapies in complex traits such as RA. PMID:23696745

Li, Gang; Diogo, Dorothée; Wu, Di; Spoonamore, Jim; Dancik, Vlado; Franke, Lude; Kurreeman, Fina; Rossin, Elizabeth J; Duclos, Grant; Hartland, Cathy; Zhou, Xuezhong; Li, Kejie; Liu, Jun; De Jager, Philip L; Siminovitch, Katherine A; Zhernakova, Alexandra; Raychaudhuri, Soumya; Bowes, John; Eyre, Steve; Padyukov, Leonid; Gregersen, Peter K; Worthington, Jane; Gupta, Namrata; Clemons, Paul A; Stahl, Eli; Tolliday, Nicola; Plenge, Robert M

2013-05-01

75

Human Genetics in Rheumatoid Arthritis Guides a High-Throughput Drug Screen of the CD40 Signaling Pathway  

PubMed Central

Although genetic and non-genetic studies in mouse and human implicate the CD40 pathway in rheumatoid arthritis (RA), there are no approved drugs that inhibit CD40 signaling for clinical care in RA or any other disease. Here, we sought to understand the biological consequences of a CD40 risk variant in RA discovered by a previous genome-wide association study (GWAS) and to perform a high-throughput drug screen for modulators of CD40 signaling based on human genetic findings. First, we fine-map the CD40 risk locus in 7,222 seropositive RA patients and 15,870 controls, together with deep sequencing of CD40 coding exons in 500 RA cases and 650 controls, to identify a single SNP that explains the entire signal of association (rs4810485, P?=?1.4×10?9). Second, we demonstrate that subjects homozygous for the RA risk allele have ?33% more CD40 on the surface of primary human CD19+ B lymphocytes than subjects homozygous for the non-risk allele (P?=?10?9), a finding corroborated by expression quantitative trait loci (eQTL) analysis in peripheral blood mononuclear cells from 1,469 healthy control individuals. Third, we use retroviral shRNA infection to perturb the amount of CD40 on the surface of a human B lymphocyte cell line (BL2) and observe a direct correlation between amount of CD40 protein and phosphorylation of RelA (p65), a subunit of the NF-?B transcription factor. Finally, we develop a high-throughput NF-?B luciferase reporter assay in BL2 cells activated with trimerized CD40 ligand (tCD40L) and conduct an HTS of 1,982 chemical compounds and FDA–approved drugs. After a series of counter-screens and testing in primary human CD19+ B cells, we identify 2 novel chemical inhibitors not previously implicated in inflammation or CD40-mediated NF-?B signaling. Our study demonstrates proof-of-concept that human genetics can be used to guide the development of phenotype-based, high-throughput small-molecule screens to identify potential novel therapies in complex traits such as RA.

Li, Gang; Diogo, Dorothee; Wu, Di; Spoonamore, Jim; Dancik, Vlado; Franke, Lude; Kurreeman, Fina; Rossin, Elizabeth J.; Duclos, Grant; Hartland, Cathy; Zhou, Xuezhong; Li, Kejie; Liu, Jun; De Jager, Philip L.; Siminovitch, Katherine A.; Zhernakova, Alexandra; Raychaudhuri, Soumya; Bowes, John; Eyre, Steve; Padyukov, Leonid; Gregersen, Peter K.; Worthington, Jane; Gupta, Namrata; Clemons, Paul A.; Stahl, Eli; Tolliday, Nicola; Plenge, Robert M.

2013-01-01

76

Bioassay-guided discovery of antibacterial agents: in vitro screening of Peperomia vulcanica, Peperomia fernandopoioana and Scleria striatinux  

PubMed Central

Background The global burden of bacterial infections is high and has been further aggravated by increasing resistance to antibiotics. In the search for novel antibacterials, three medicinal plants: Peperomia vulcanica, Peperomia fernandopoioana (Piperaceae) and Scleria striatinux (Cyperaceae), were investigated for antibacterial activity and toxicity. Methods Crude extracts of these plants were tested by the disc diffusion method against six bacterial test organisms followed by bio-assay guided fractionation, isolation and testing of pure compounds. The minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations were measured by the microdilution method. The acute toxicity of the active extracts and cytotoxicity of the active compound were performed in mice and mammalian cells, respectively. Results The diameter of the zones of inhibition (DZI) of the extracts ranged from 7–13?mm on Escherichia coli and Staphylococcus aureus of which the methylene chloride:methanol [1:1] extract of Scleria striatinux recorded the highest activity (DZI?=?13?mm). Twenty-nine pure compounds were screened and one, Okundoperoxide, isolated from S. striatinux, recorded a DZI ranging from 10–19?mm on S. aureus. The MICs and MBCs indicated that the Peperomias had broad-spectrum bacteriostatic activity. Toxicity tests showed that Okundoperoxide may have a low risk of toxicity with an LC50 of 46.88??g/mL. Conclusions The antibacterial activity of these plants supports their use in traditional medicine. The pure compound, Okundoperoxide, may yield new antibacterial lead compounds following medicinal chemistry exploration.

2012-01-01

77

Modelling plastic scintillator response to gamma rays using light transport incorporated FLUKA code.  

PubMed

The response function of NE102 plastic scintillator to gamma rays has been simulated using a joint FLUKA+PHOTRACK Monte Carlo code. The multi-purpose particle transport code, FLUKA, has been responsible for gamma transport whilst the light transport code, PHOTRACK, has simulated the transport of scintillation photons through scintillator and lightguide. The simulation results of plastic scintillator with/without light guides of different surface coverings have been successfully verified with experiments. PMID:22341953

Ranjbar Kohan, M; Etaati, G R; Ghal-Eh, N; Safari, M J; Afarideh, H; Asadi, E

2012-05-01

78

Scintillators and applications thereof  

US Patent & Trademark Office Database

Scintillators of various constructions and methods of making and using the same are provided. In some embodiments, a scintillator comprises at least one radiation absorption region and at least one spatially discrete radiative exciton recombination region.

2014-07-15

79

Scintillator Manufacture at Fermilab.  

National Technical Information Service (NTIS)

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....

K. Mellott A. Pla-Dalmau

1998-01-01

80

Screening of scFv-displaying phages recognizing distinct extracellular domains of EGF receptor by target-guided proximity labeling method.  

PubMed

We recently constructed the scFv-displaying phage library with extremely high repertoire and have successfully utilized for screening scFv antibodies against various proteins, polysaccharides and glyco-lipids. Here, we developed a new screening strategy to isolate scFv antibodies against cell surface EGF receptor (EGFR). For this, we applied two slightly different methods of "target-guided proximity labeling," such as Proximity selection (ProxiMol) method and a new sulfo-SBED labeling method with the aide of monoclonal anti-human EGFR antibody B4G7 as a guide molecule. ProxiMol method relies on the Biotin-labeling of scFv-displaying phages that bound to the target in a vicinity of 100? from the guide molecule, whereas sulfo-SBED method transfers Biotin to scFv-displaying phages, which bound to the target in a distance of 20 ?. After two rounds of panning on the EGFR-overexpressing A431 cells starting from approx. 1 × 10¹² pfu, 47 each of Biotin-labeled scFv-displaying phages were recovered using Streptoavidin-coated magnetic beads, and among them total 11 scFv-phages were found to be definitely positive for binding to A431 cell surface by ELISA assay. Restriction mapping and sequencing analysis of these scFv-phage DNAs revealed that they encode 4 different scFv-nucleotide sequences in total. Immuno-fluorescent microscopy provided evidence that these 4 scFv antibodies bind specifically to EGFR on the A431 cells, showing slightly different staining patterns. Thus, "target-guided proximity labeling" methods were powerful for isolating scFv-displaying phages that recognize distinct extracellular domains of the target receptor. This novel screening strategy could be applicable to many other cell surface antigens and receptors. PMID:21782821

Chang, Chialun; Takayanagi, Atsushi; Yoshida, Tetsuhiko; Shimizu, Nobuyoshi

2011-09-30

81

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

82

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. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)

1998-11-09

83

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

84

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

85

A LIQUID-CONTACT SCINTILLATION ALPHA COUNTER  

Microsoft Academic Search

A protected alpha-sensitive scintillation screen has been developed ; which can be used in direct contact with aqueous or organic liquid process ; streams, yielding a measure of the concentrations of alpha-emitting radioisotopes ; in the stream. Concentrations of 0.05 to 10 grams per liter of plutonium can be ; measured with a precision of about plus or minus 20

U. L. Upson; P. E. Brown

1959-01-01

86

Pulsar scintillation patterns and strangelets  

NASA Astrophysics Data System (ADS)

We propose that interstellar extreme scattering events, usually observed as pulsar scintillations, may be caused by a coherent agent rather than the usually assumed turbulence of H2 clouds. We find that the penetration of a flux of ionizing, positively charged strangelets or quark nuggets into a dense interstellar hydrogen cloud may produce ionization trails. Depending on the specific nature and energy of the incoming droplets, diffusive propagation or even capture in the cloud are possible. As a result, enhanced electron densities may form and constitute a lens-like scattering screen for radio pulsars and possibly for quasars.

Pérez-García, M. Ángeles; Silk, Joseph; Pen, Ue-Li

2013-12-01

87

Integration of Microfractionation, qNMR and zebrafish screening for the in vivo bioassay-guided isolation and quantitative bioactivity analysis of natural products.  

PubMed

Natural products (NPs) are an attractive source of chemical diversity for small-molecule drug discovery. Several challenges nevertheless persist with respect to NP discovery, including the time and effort required for bioassay-guided isolation of bioactive NPs, and the limited biomedical relevance to date of in vitro bioassays used in this context. With regard to bioassays, zebrafish have recently emerged as an effective model system for chemical biology, allowing in vivo high-content screens that are compatible with microgram amounts of compound. For the deconvolution of the complex extracts into their individual constituents, recent progress has been achieved on several fronts as analytical techniques now enable the rapid microfractionation of extracts, and microflow NMR methods have developed to the point of allowing the identification of microgram amounts of NPs. Here we combine advanced analytical methods with high-content screening in zebrafish to create an integrated platform for microgram-scale, in vivo NP discovery. We use this platform for the bioassay-guided fractionation of an East African medicinal plant, Rhynchosia viscosa, resulting in the identification of both known and novel isoflavone derivatives with anti-angiogenic and anti-inflammatory activity. Quantitative microflow NMR is used both to determine the structure of bioactive compounds and to quantify them for direct dose-response experiments at the microgram scale. The key advantages of this approach are (1) the microgram scale at which both biological and analytical experiments can be performed, (2) the speed and the rationality of the bioassay-guided fractionation - generic for NP extracts of diverse origin - that requires only limited sample-specific optimization and (3) the use of microflow NMR for quantification, enabling the identification and dose-response experiments with only tens of micrograms of each compound. This study demonstrates that a complete in vivo bioassay-guided fractionation can be performed with only 20 mg of NP extract within a few days. PMID:23700445

Bohni, Nadine; Cordero-Maldonado, María Lorena; Maes, Jan; Siverio-Mota, Dany; Marcourt, Laurence; Munck, Sebastian; Kamuhabwa, Appolinary R; Moshi, Mainen J; Esguerra, Camila V; de Witte, Peter A M; Crawford, Alexander D; Wolfender, Jean-Luc

2013-01-01

88

Recent development in organic scintillators  

NASA Technical Reports Server (NTRS)

Discussion on recent developments of organic scintillators includes studies of organic compounds that form glass-like masses which scintillate and are stable at room temperature, correlations between molecular structure of organic scintillators and self-quenching, recently developed fast scintillators, and applications of liquid-scintillation counters.

Horrocks, D. L.; Wirth, H. O.

1969-01-01

89

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

90

The Use of Energy Information in Plastic Scintillator Material  

SciTech Connect

Plastic scintillator material is often used for gamma-ray detection in many applications due to its relatively good sensitivity and cost-effectiveness compared to other detection materials. However, due to the dominant Compton scattering interaction mechanism, full energy peaks are not observed in plastic scintillator spectra and isotopic identification is impossible. Typically plastic scintillator detectors are solely gross count detectors. In some safeguards and security applications, such as radiation portal monitors for vehicle screening, naturally-occurring radioactive material (NORM) often triggers radiation alarms and results in innocent or nuisance alarms. The limited energy information from plastic scintillator material can be used to discriminate the NORM from targeted materials and reduce the nuisance alarm rate. An overview of the utilization of the energy information from plastic scintillator material will be presented, with emphasis on the detection capabilities and potential limitations for safeguards and security applications. (PIET-43741-TM-490)

Ely, James H.; Anderson, Kevin K.; Bates, Derrick J.; Kouzes, Richard T.; Lopresti, Charles A.; Runkle, Robert C.; Siciliano, Edward R.; Weier, Dennis R.

2008-06-15

91

Ionizations scintillation detectors  

NASA Astrophysics Data System (ADS)

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

Policarpo, A. J. P. L.

92

Scintillation study at Varanasi  

NASA Astrophysics Data System (ADS)

A scintillation study carried out at Varanasi (geomag. lat., 14 deg 55 min N) using geostationary satellite FLEETSAT signals at 244.168 MHz is reported. A conventional recording system has been used. The time of peak occurrence is found to vary from month to month and is predominant in the premidnight period. The seasonal dependence of nighttime scintillation variation shows a maximum occurrence of 20 percent for equinox at around 2100-2200 hrs IST. The effect of magnetic activity on scintillation occurrence was examined and it is found that there was no scintillation at all in summer on quiet days in the premidnight period. The computed scintillation index also exhibits nighttime variation. These features are compared with available results at low and midlatitude stations.

Singh, R. P.; Singh, U. P.; Singh, A. K.; Singh, R. N.

1993-02-01

93

Patent foramen ovale and scuba diving: a practical guide for physicians on when to refer for screening  

PubMed Central

Divers are taught some basic physiology during their training. There is therefore some underlying knowledge and understandable concern in the diving community about the presence of a patent foramen ovale (PFO) as a cause of decompression illness (DCI). There is an agreement that PFO screening should not be done routinely on all divers; however, when to screen selected divers is not clear. We present the basic physiology and current existing guidelines for doctors, advice on the management and identify which groups of divers should be referred for consideration of PFO screening. Venous bubbles after diving and right to left shunts are common, but DCI is rare. Why this is the case is not clear, but the divers look to doctors for guidance on PFO screening and closure; both of which are not without risks. Ideally, we should advise and apply guidelines that are consistent and based on best available evidence. We hope this guideline and flow chart helps address these issues with regard to PFOs and diving.

2013-01-01

94

Ligand-guided optimization of CXCR4 homology models for virtual screening using a multiple chemotype approach  

Microsoft Academic Search

CXCR4 is a G-protein coupled receptor for CXCL12 that plays an important role in human immunodeficiency virus infection, cancer\\u000a growth and metastasization, immune cell trafficking and WHIM syndrome. In the absence of an X-ray crystal structure, theoretical\\u000a modeling of the CXCR4 receptor remains an important tool for structure–function analysis and to guide the discovery of new\\u000a antagonists with potential clinical

Marco A. C. NevesSergio; Sérgio Simões; M. Luisa Sá e Melo

2010-01-01

95

Detection efficiency loss in a position sensitive scintillator hodoscope neutron detector  

Microsoft Academic Search

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

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

1989-01-01

96

Scintillating fiber tracking techniques  

SciTech Connect

The current status of the field of scintillating fiber detection and tracking is briefly reviewed, and avenues for further work are suggested. Attention is given to the core material, cladding material, and extra-mural absorber to be used in the scintillating fibers, as well as to the properties of attenuation length, radiation resistance, and fiber profile. Some examples are given of successful recording of tracks and interactions. Current developments are mentioned in relation to plastic and glass fibers and liquid capillaries. (LEW)

Ruchti, R.

1986-02-01

97

Condensed xenon scintillators  

Microsoft Academic Search

Liquid and solid xenon were investigated as scintillator media for the detection of charged particles. The LET dependence of the integral light output was studied over a wide range of ionization densities using alpha and beta particles and heavy ions of 1.4 MeV\\/amu. For solid xenon, scintillation decay times were measured by the delayed single-photon method. For liquid xenon, a

W. Baum; S. Gotz; H. Heckwolf; P. Heeg; M. Mutterer; J. P. Theobald

1988-01-01

98

Condensed krypton scintillators  

Microsoft Academic Search

Liquid and solid krypton have been studied as scintillators. Attenuation length for Kr scintillation light was determined to be about 1m, after the Kr was purified by a hot Ca-getter and by a Ti discharge purifier in liquid phase. Two detectors (75 and 51 in size, respectively) were tested as stop-counters in a time-of-flight experiment using 1-2 GeV\\/c particle beams

D. Yu. Akimov; A. I. Bolozdynya; D. L. Churakov; A. V. Koutchenkov; V. F. Kuzichev; V. N. Lebendenko; I. A. Rogovsky; M. Chen; V. Yu. Chepel; V. V. Sushkov

1993-01-01

99

Simulating intergalactic quasar scintillation  

NASA Astrophysics Data System (ADS)

Intergalactic scintillation of distant quasars is sensitive to free electrons and therefore complements Ly? absorption-line experiments probing the neutral intergalactic medium (IGM). We present a new scheme to compute IGM refractive scintillation effects on distant sources in combination with adaptive mesh refinement cosmological simulations. First, we validate our model by reproducing the well-known interstellar scintillation (ISS) of Galactic sources. The simulated cosmic density field is then used to infer the statistical properties of intergalactic scintillation. Contrary to previous claims, we find that the scattering measure of the simulated IGM at z < 2 is = 3.879, i.e. almost 40 times larger than that for the usually assumed smooth IGM. This yields an average modulation index ranging from 0.01 (?s = 5 GHz) up to 0.2 (?s = 50 GHz); above ?s ? 30 GHz the IGM contribution dominates over ISS modulation. We compare our model with data from a 0.3 ? z ? 2 quasar sample observed at ?obs = 8.4 GHz. For this high-frequency (10.92 ? ?s ? 25.2), high-galactic-latitude sample ISS is negligible, and IGM scintillation can reproduce the observed modulation with a 4 per cent accuracy, without invoking intrinsic source variability. We conclude by discussing the possibility of using IGM scintillation as a tool to pinpoint the presence of intervening high-z groups/clusters along the line of sight, thus making it a probe suitably complementing Sunyaev-Zel'dovich data recently obtained by Planck.

Pallottini, A.; Ferrara, A.; Evoli, C.

2013-10-01

100

Efficient screening of fungal cellobiohydrolase class I enzymes for thermostabilizing sequence blocks by SCHEMA structure-guided recombination.  

PubMed

We describe an efficient SCHEMA recombination-based approach for screening homologous enzymes to identify stabilizing amino acid sequence blocks. This approach has been used to generate active, thermostable cellobiohydrolase class I (CBH I) enzymes from the 390 625 possible chimeras that can be made by swapping eight blocks from five fungal homologs. Constructing and characterizing the parent enzymes and just 32 'monomeras' containing a single block from a homologous enzyme allowed stability contributions to be assigned to 36 of the 40 blocks from which the CBH I chimeras can be assembled. Sixteen of 16 predicted thermostable chimeras, with an average of 37 mutations relative to the closest parent, are more thermostable than the most stable parent CBH I, from the thermophilic fungus Talaromyces emersonii. Whereas none of the parent CBH Is were active >65°C, stable CBH I chimeras hydrolyzed solid cellulose at 70°C. In addition to providing a collection of diverse, thermostable CBH Is that can complement previously described stable CBH II chimeras (Heinzelman et al., Proc. Natl Acad. Sci. USA 2009;106:5610-5615) in formulating application-specific cellulase mixtures, the results show the utility of SCHEMA recombination for screening large swaths of natural enzyme sequence space for desirable amino acid blocks. PMID:20847102

Heinzelman, Pete; Komor, Russell; Kanaan, Arvind; Romero, Philip; Yu, Xinlin; Mohler, Shannon; Snow, Christopher; Arnold, Frances

2010-11-01

101

Monte Carlo simulation of a novel water-equivalent electronic portal imaging device using plastic scintillating fibers  

SciTech Connect

Purpose: Most electronic portal imaging devices (EPIDs) developed so far use a thin Cu plate/phosphor screen to convert x-ray energies into light photons, while maintaining a high spatial resolution. This results in a low x-ray absorption and thus a low quantum efficiency (QE) of approximately 2-4% for megavoltage (MV) x-rays. A significant increase of QE is desirable for applications such as MV cone-beam computed tomography (MV-CBCT). Furthermore, the Cu plate/phosphor screen contains high atomic number (high-Z) materials, resulting in an undesirable over-response to low energy x-rays (due to photoelectric effect) as well as high energy x-rays (due to pair production) when used for dosimetric verification. Our goal is to develop a new MV x-ray detector that has a high QE and uses low-Z materials to overcome the obstacles faced by current MV x-ray imaging technologies. Methods: A new high QE and low-Z EPID is proposed. It consists of a matrix of plastic scintillating fibers embedded in a water-equivalent medium and coupled to an optically sensitive 2D active matrix flat panel imager (AMFPI) for image readout. It differs from the previous approach that uses segmented crystalline scintillators made of higher density and higher atomic number materials to detect MV x-rays. The plastic scintillating fibers are focused toward the x-ray source to avoid image blurring due to oblique incidence of off-axis x-rays. When MV x-rays interact with the scintillating fibers in the detector, scintillation light will be produced. The light photons produced in a fiber core and emitted within the acceptance angle of the fiber will be guided toward the AMFPI by total internal reflection. A Monte Carlo simulation has been used to investigate imaging and dosimetric characteristics of the proposed detector under irradiation of MV x-rays. Results: Properties, such as detection efficiency, modulation transfer function, detective quantum efficiency (DQE), energy dependence of detector response, and water-equivalence of dose response have been investigated. It has been found that the zero frequency DQE of the proposed detector can be up to 37% at 6 MV. The detector, also, is water-equivalent with a relatively uniform response to different energy x-rays as compared to current EPIDs. Conclusions: The results of our simulations show that, using plastic scintillating fibers, it is possible to construct a water-equivalent EPID that has a better energy response and a higher detection efficiency than current flat panel based EPIDs.

Teymurazyan, A.; Pang, G. [Imaging Research, Sunnybrook Health Sciences Centre, Department of Medical Biophysics, University of Toronto, Toronto M4N 3M5 (Canada); Imaging Research, Sunnybrook Health Sciences Centre, Department of Medical Biophysics, University of Toronto, Toronto M4N 3M5 (Canada); Odette Cancer Centre, Toronto M4N 3M5 (Canada); Department of Radiation Oncology, University of Toronto, Toronto M5S 3E2 (Canada) and Department of Physics, Ryerson University,Toronto M5B 2K3 (Canada)

2012-03-15

102

Scintillation light emission studies of LSO scintillators  

SciTech Connect

UV and {gamma}-ray excited luminescence and nuclear spectroscopy were used to study the relationship between the scintillation mechanisms of LSO and the spectroscopic characteristics obtained with PMT and APD readouts at room temperature. No correlation was found between scintillation decay time and light output. Like other investigators, the authors observed the existence of two distinct luminescence centers, Ce1 and Ce2, that mainly give rise to short (420 nm) and long (440 nm) emission wavelengths. The measurements showed that different LSO crystals excited by {gamma}-rays have emission spectra with largely different shapes and maxima depending on the relative population and luminescence efficiency of these centers. It was also found that the poor energy resolution of LSO and YSO scintillators is well correlated with the coexistence of the two competing luminescence mechanisms. The prevalence of either Ce1 or Ce2 luminescence tends to reduce the variance of light emission and, thus, to improve energy resolution. Inversely, the coexistence of the two centers increases variance and degrades energy resolution.

Saoudi, A.; Pepin, C.; Houde, D.; Lecomte, R.

1999-12-01

103

Study of scintillation in natural and synthetic quartz and methacrylate  

NASA Astrophysics Data System (ADS)

Samples from different materials typically used as optical windows or light guides in scintillation detectors were studied in a very low background environment, at the Canfranc Underground Laboratory, searching for scintillation. A positive result can be confirmed for natural quartz: two distinct scintillation components have been identified, not being excited by an external gamma source. Although similar effect has not been observed neither for synthetic quartz nor for methacrylate, a fast light emission excited by intense gamma flux is evidenced for all the samples in our measurements. These results could affect the use of these materials in low energy applications of scintillation detectors requiring low radioactive background conditions, as they entail a source of background.

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

2014-06-01

104

Equatorial scintillation predictions from C\\/NOFS Planar Langmuir Probe electron density fluctuation data  

Microsoft Academic Search

Data from the Planar Langmuir Probe onboard Communication\\/ Navigation Outage Forecasting System will be combined with coherent scatter radar and scintillation measurements to analyze the performance of different propagation models of satellite signals. This work will characterize: (i) the prediction capability of a purely spacebased phase-screen scintillation model in comparison with another that represents the variation of the irregularity strength

Emanoel Costa; Eurico R. de Paula; L. F. C. de Rezende; Keith M. Groves; Patrick A. Roddy

2011-01-01

105

Adrenal suppression: A practical guide to the screening and management of this under-recognized complication of inhaled corticosteroid therapy  

PubMed Central

Inhaled corticosteroids (ICSs) are the most effective anti-inflammatory agents available for the treatment of asthma and represent the mainstay of therapy for most patients with the disease. Although these medications are considered safe at low-to-moderate doses, safety concerns with prolonged use of high ICS doses remain; among these concerns is the risk of adrenal suppression (AS). AS is a condition characterized by the inability to produce adequate amounts of the glucocorticoid, cortisol, which is critical during periods of physiological stress. It is a proven, yet under-recognized, complication of most forms of glucocorticoid therapy that can persist for up to 1 year after cessation of corticosteroid treatment. If left unnoticed, AS can lead to significant morbidity and even mortality. More than 60 recent cases of AS have been described in the literature and almost all cases have involved children being treated with ?500 ?g/day of fluticasone. The risk for AS can be minimized through increased awareness and early recognition of at-risk patients, regular patient follow-up to ensure that the lowest effective ICS doses are being utilized to control asthma symptoms, and by choosing an ICS medication with minimal adrenal effects. Screening for AS should be considered in any child with symptoms of AS, children using high ICS doses, or those with a history of prolonged oral corticosteroid use. Cases of AS should be managed in consultation with a pediatric endocrinologist whenever possible. In patients with proven AS, stress steroid dosing during times of illness or surgery is needed to simulate the protective endogenous elevations in cortisol levels that occur with physiological stress. This article provides an overview of current literature on AS as well as practical recommendations for the prevention, screening and management of this serious complication of ICS therapy.

2011-01-01

106

Discrimination of Naturally Occurring Radioactive Material in Plastic Scintillator Material  

SciTech Connect

Plastic scintillator material is used in many applications for the detection of gamma-rays from radioactive material, primarily due to the sensitivity per unit cost compared to other detection materials. However, the resolution and lack of full-energy peaks in the plastic scintillator material prohibits detailed spectroscopy. Therefore, other materials such as doped sodium iodide are used for spectroscopic applications. The limited spectroscopic information can however be exploited in plastic scintillator materials to provide some discrimination. The discrimination between man-made and naturally occurring sources would be useful in reducing alarm screening for radiation detection applications which target man-made sources. The results of applying the limited energy information from plastic scintillator material for radiation portal monitors are discussed.

Ely, James H.; Kouzes, Richard T.; Geelhood, Bruce D.; Schweppe, John E.; Warner, Ray A.

2003-08-19

107

Surface preparation and coupling in plastic scintillator dosimetry.  

PubMed

One way to improve the performance of scintillation dosimeters is to increase the light-collection efficiency at the coupling interfaces of the detector system. We performed a detailed study of surface preparation of scintillating fibers and their coupling with clear optical fibers to minimize light loss and increase the amount of light collected. We analyzed fiber-surface polishing with aluminum oxide sheets, coating fibers with magnesium oxide, and the use of eight different coupling agents (air, three optical gels, an optical curing agent, ultraviolet light, cyanoacrylate glue, and acetone). We prepared 10 scintillating fiber and clear optical fiber light guide samples to test different coupling methods. To test the coupling, we first cut both the scintillating fiber and the clear optical fiber. Then, we cleaned and polished both ends of both fibers. Finally, we coupled the scintillating fiber with the clear optical fiber in either a polyethylene jacket or a V-grooved support depending on the coupling agent used. To produce more light, we used an ultraviolet lamp to stimulate scintillation. A typical series of similar couplings showed a standard deviation in light-collection efficiency of 10%. This can be explained by differences in the surface preparation quality and alignment of the scintillating fiber with the clear optical fiber. Absence of surface polishing reduced the light collection by approximately 40%, and application of magnesium oxide on the proximal end of the scintillating fiber increased the amount of light collected from the optical fiber by approximately 39%. Of the coupling agents, we obtained the best results using one of the optical gels. Because a large amount of the light produced inside a scintillator is usually lost, better light-collection efficiency will result in improved sensitivity. PMID:17022248

Ayotte, Guylaine; Archambault, Louis; Gingras, Luc; Lacroix, Frédéric; Beddar, A Sam; Beaulieu, Luc

2006-09-01

108

Surface preparation and coupling in plastic scintillator dosimetry  

SciTech Connect

One way to improve the performance of scintillation dosimeters is to increase the light-collection efficiency at the coupling interfaces of the detector system. We performed a detailed study of surface preparation of scintillating fibers and their coupling with clear optical fibers to minimize light loss and increase the amount of light collected. We analyzed fiber-surface polishing with aluminum oxide sheets, coating fibers with magnesium oxide, and the use of eight different coupling agents (air, three optical gels, an optical curing agent, ultraviolet light, cyanoacrylate glue, and acetone). We prepared 10 scintillating fiber and clear optical fiber light guide samples to test different coupling methods. To test the coupling, we first cut both the scintillating fiber and the clear optical fiber. Then, we cleaned and polished both ends of both fibers. Finally, we coupled the scintillating fiber with the clear optical fiber in either a polyethylene jacket or a V-grooved support depending on the coupling agent used. To produce more light, we used an ultraviolet lamp to stimulate scintillation. A typical series of similar couplings showed a standard deviation in light-collection efficiency of 10%. This can be explained by differences in the surface preparation quality and alignment of the scintillating fiber with the clear optical fiber. Absence of surface polishing reduced the light collection by approximately 40%, and application of magnesium oxide on the proximal end of the scintillating fiber increased the amount of light collected from the optical fiber by approximately 39%. Of the coupling agents, we obtained the best results using one of the optical gels. Because a large amount of the light produced inside a scintillator is usually lost, better light-collection efficiency will result in improved sensitivity.

Ayotte, Guylaine; Archambault, Louis; Gingras, Luc; Lacroix, Frederic; Beddar, A. Sam; Beaulieu, Luc [Departement de physique, de genie physique et d'optique, Universite Laval, Quebec City, Quebec, G1K7P4 (Canada) and Departement de Radio-Oncologie, Hotel Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec City, Quebec, G1R2J6 (Canada); Departement de physique, de genie physique et d'optique, Universite Laval, Quebec City, Quebec, G1K7P4 (Canada) and Department de Radio-Oncologie, Hotel Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec City, Quebec, G1R2J6 (Canada) and Department of Radiation Physics, Division of Radiation Oncology, 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 City, Quebec, G1K7P4 (Canada) and Department de Radio-Oncologie, Hotel Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec City, Quebec, G1R2J6 (Canada); Department of Radiation Physics, Division of Radiation Oncology, 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 City, Quebec, G1K7P4 (Canada) and Department de Radio-Oncologie, Hotel Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec City, Quebec, G1R2J6 (Canada)

2006-09-15

109

Development of radiation hard scintillators.  

National Technical Information Service (NTIS)

The authors have demonstrated that the radiation stability of scintillators made from styrene polymer is very much improved by compounding with pentaphenyltrimethyltrisiloxane (DC 705 vacuum pump oil). The resulting scintillators are softer than desired, ...

F. Markley M. Davidson J. Keller G. Foster A. Pla-Dalmau

1993-01-01

110

Scintillator plate calorimetry  

SciTech Connect

Calorimetry using scintillator plates or tiles alternated with sheets of (usually heavy) passive absorber has been proven over multiple generations of collider detectors. Recent detectors including UA1, CDF, and ZEUS have shown good results from such calorimeters. The advantages offered by scintillator calorimetry for the SSC environment, in particular, are speed (<10 nsec), excellent energy resolution, low noise, and ease of achieving compensation and hence linearity. On the negative side of the ledger can be placed the historical sensitivity of plastic scintillators to radiation damage, the possibility of nonuniform response because of light attenuation, and the presence of cracks for light collection via wavelength shifting plastic (traditionally in sheet form). This approach to calorimetry is being investigated for SSC use by a collaboration of Ames Laboratory/Iowa State University, Argonne National Laboratory, Bicron Corporation, Florida State University, Louisiana State University, University of Mississippi, Oak Ridge National Laboratory, Virginia Polytechnic Institute and State University, Westinghouse Electric Corporation, and University of Wisconsin.

Price, L.E.

1990-01-01

111

Liquid Scintillator Purification  

SciTech Connect

The KamLAND collaboration has studied background requirements and purification methods needed to observe the 7Be neutrino from the sun. First we will discuss the present background situation in KamLAND where it is found that the main background components are 210Pb and 85Kr. It is then described how to purify the liquid scintillator. The present status and results on how to remove 210Pb from the liquid scintillator are discussed. Specifically, the detailed analysis of the effects of distillation and adsorption techniques are presented.

Kishimoto, Y. [Research Center for Neutrino Science, Tohoku University (Japan)

2005-09-08

112

Extruding plastic scintillator at Fermilab  

Microsoft Academic Search

An understanding of the costs involved in the production of plastic scintillators and the development of a less expensive material have become necessary with the prospects of building very large plastic scintillation detectors. Several factors contribute to the high cost of plastic scintillating sheets, but the principal reason is the labor-intensive nature of the manufacturing process. In order to significantly

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

2003-01-01

113

Radiation damage in scintillating crystals  

Microsoft Academic Search

Crystal Calorimetry in future high-energy physics experiments faces a new challenge to maintain its precision in a hostile radiation environment. This paper discusses the effects of radiation damage in scintillating crystals, and concludes that the predominant radiation damage effect in crystal scintillators is the radiation-induced absorption, or color center formation, not the loss of scintillation light yield. The importance of

Ren-yuan Zhu

1998-01-01

114

Laser beam scintillation beyond the turbulent atmosphere A numerical computation  

NASA Technical Reports Server (NTRS)

The extended Huygens-Fresnel formulation for propagation through turbulence is used to examine scintillation of a finite laser beam. The method is demonstrated analytically for propagation beyond a weak Gaussian phase screen. A numerical integration technique is used to extend the results to a more realistic turbulence model. Results are compared with existing Gaussian beam propagation theory.

Bufton, J. L.; Taylor, L. S.

1976-01-01

115

Intrinsic Scintillator Resolution  

Microsoft Academic Search

Measurements of spectrometer resolution using an electron gun and phosphor type of light source yield values considerably better than those obtained from scintillations in a phosphor. Line widths of about 3.4 per cent have been obtained at a pulse height equivalent to 661 kev in NaI. An investigation is being made to determine the causes of this difference. A number

G. G. Kelley; P. R. Bell; R. C. Davis; N. H. Lazar

1956-01-01

116

Polysiloxane scintillator composition  

DOEpatents

A plastic scintillator useful for detecting ionizing radiation comprising a matrix which comprises an optically transparent polysiloxane having incorporated therein at least one ionizing radiation-hard fluor capable of converting electromagnetic energy produced in the polysiloxane upon absorption of ionizing radiation to detectable light.

Walker, J.K.

1992-05-05

117

Study of Equatorial Scintillations.  

National Technical Information Service (NTIS)

Observations of the amplitude scintillations produced by the F-region in equatorial areas are presented. The equipment used for conducting the observations is described. The use of transmissions from the ATS-1, ATS-3, and ATS-5 for obtaining data is descr...

J. Pomalaza R. Woodman G. Tisnado E. Nakasone

1972-01-01

118

Polysiloxane scintillator composition  

DOEpatents

A plastic scintillator useful for detecting ionizing radiation comprising a matrix which comprises an optically transparent polysiloxane having incorporated therein at least one ionizing radiation-hard fluor capable of converting electromagnetic energy produced in the polysiloxane upon absorption of ionizing radiation to detectable light.

Walker, James K. (Gainesville, FL)

1992-01-01

119

Boron loaded scintillator  

DOEpatents

A scintillating composition for detecting neutrons and other radiation comprises a phenyl containing silicone rubber with carborane units and at least one phosphor molecule. The carbonate units can either be a carborane molecule dispersed in the rubber with the aid of a compatibilization agent or can be covalently bound to the silicone.

Bell, Zane William (Oak Ridge, TN) [Oak Ridge, TN; Brown, Gilbert Morris (Knoxville, TN) [Knoxville, TN; Maya, Leon (Knoxville, TN) [Knoxville, TN; Sloop, Jr., Frederick Victor (Oak Ridge, TN); Sloop, Jr., Frederick Victor [Oak Ridge, TN

2009-10-20

120

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

121

Scintillator requirements for medical imaging  

SciTech Connect

Scintillating materials are used in a variety of medical imaging devices. This paper presents a description of four medical imaging modalities that make extensive use of scintillators: planar x-ray imaging, x-ray computed tomography (x-ray CT), SPECT (single photon emission computed tomography) and PET (positron emission tomography). The discussion concentrates on a description of the underlying physical principles by which the four modalities operate. The scintillator requirements for these systems are enumerated and the compromises that are made in order to maximize imaging performance utilizing existing scintillating materials are discussed, as is the potential for improving imaging performance by improving scintillator properties.

Moses, William W.

1999-09-01

122

Coherence properties of wideband satellite signals caused by ionospheric scintillation  

NASA Technical Reports Server (NTRS)

Radio scintillation on satellite signals caused by small-scale irregularities in F-region ionospheric electron density can be an important limitation on earth-satellite communication and navigation systems. Scintillation imposes distortion in both amplitude and phase on wideband signals. In the present work, the shallow-modulated phase screen theory is developed in terms of coherence bandwidth including a model based on a turbulent-like power-law description of the irregularities. The model results usually show a greater coherence bandwidth in the signal phase than in the signal amplitude. Therefore, systems that require phase coherence over a large bandwidth should be less affected than those requiring amplitude coherence.

Rufenach, C. L.

1975-01-01

123

A computer model of high-latitude scintillation  

NASA Astrophysics Data System (ADS)

The DNA Wideband satellite experiment provided extensive data on scintillation produced in high-altitude structured plasmas. A computer program, WBMOD, is being developed to summarize those data in an applications-oriented way. The program contains the phase-screen scattering theory of Rino and a morphological description of ionospheric irregularities (thus far only at auroral latitudes) based on Wideband observations. It permits a user to compute scintillation indices for both phase and intensity as a function of system operating parameters and solar-ionospheric disturbance level. Correction is made for multiple scatter, and the user may choose either one-way (communication) or two-way (radar) propagation.

Fremouw, E. J.

1982-01-01

124

Liquid capillary scintillation detectors  

SciTech Connect

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

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

1990-04-01

125

The effect of scintillator response on signal difference to noise ratio in X-ray medical imaging  

NASA Astrophysics Data System (ADS)

The aim of the present study was to examine the effect of scintillator material properties on the signal difference to noise ratio ( SdNR) under X-ray imaging conditions. To this aim, SdNR was modelled in terms of scintillator material properties such as the quantum detection efficiency (QDE), the intrinsic energy conversion efficiency (ICE) and the light transmission efficiency (LTE). Scintillators were assumed to be in the form of scintillator layers (phosphor screens) with various thicknesses ranging from 70 to 110 mg/cm 2. Data on the X-ray absorption and optical properties of the scintillators were either calculated from tabulated data, i.e. X-ray attenuation coefficients for QDE estimation, or were obtained from previous experimental studies. It was found that in a wide range of X-ray tube voltages the Gd 2O 2S:Tb scintillator produced higher SdNR values, while the CsI:Tl scintillator was better at lower voltages (below 65 kVp). It was additionally verified that, in the range of X-ray diagnostic energies, SdNR increases with the thickness of the scintillator layer screen. In conclusion, SdNR may be critically affected by scintillator properties and, hence, it may be significantly improved by appropriately selecting the type and thickness of the phosphor screen to be integrated into an imaging system.

Ninos, K.; Cavouras, D.; Fountos, G.; Kandarakis, I.

2010-10-01

126

Calculations of equatorial scintillations at VHF and gigahertz frequencies based on a new model of the disturbed equatorial ionosphere  

Microsoft Academic Search

The weak scattering, thin screen theory of scintillation of radio stars and satellites has been applied, in a mathematically rigorous way, to the observations of the plasma density structure deduced from rocket and radar measurements during equatorial spread F conditions. It is shown that bottomside spread F is capable of producing moderate scintillation at VHF, but not at gigahertz frequencies.

Emanoel Costa; M. C. Kelly

1976-01-01

127

Scintillation Proximity Assay of Arginine Methylation  

PubMed Central

Methylation of arginine residues, catalyzed by protein arginine methyltransferases (PRMTs), is one important protein post-translational modification involved in epigenetic regulation of gene expression. A fast and effective assay for PRMT can provide valuable information for dissecting the biological functions of PRMTs, as well as for screening small-molecule inhibitors of arginine methylation. Currently, among the methods used for PRMT activity measurement, many contain laborious separation procedures, which restrict the applications of these assays for high-throughput screening (HTS) in drug discovery. The authors report here a mix-and-measure method to measure PRMT activity based on the principle of scintillation proximity assay (SPA). In this assay, 3H-AdoMet was used as methyl donor, and biotin-modified histone H4 peptide served as a methylation substrate. Following the methylation reaction catalyzed by PRMTs, streptavidin-coated SPA beads were added to the reaction solution, and SPA signals were detected by a MicroBeta scintillation counter. No separation step is needed, which simplifies the assay procedure and greatly enhances the assay speed. Particularly, the miniaturization and robustness suggest that this method is suited for HTS of PRMT inhibitors.

Wu, Jiang; Xie, Nan; Feng, You; Zheng, Y. George

2011-01-01

128

Scintillation proximity assay of arginine methylation.  

PubMed

Methylation of arginine residues, catalyzed by protein arginine methyltransferases (PRMTs), is one important protein posttranslational modification involved in epigenetic regulation of gene expression. A fast and effective assay for PRMT can provide valuable information for dissecting the biological functions of PRMTs, as well as for screening small-molecule inhibitors of arginine methylation. Currently, among the methods used for PRMT activity measurement, many contain laborious separation procedures, which restrict the applications of these assays for high-throughput screening (HTS) in drug discovery. The authors report here a mix-and-measure method to measure PRMT activity based on the principle of scintillation proximity assay (SPA). In this assay, (3)H-AdoMet was used as methyl donor, and biotin-modified histone H4 peptide served as a methylation substrate. Following the methylation reaction catalyzed by PRMTs, streptavidin-coated SPA beads were added to the reaction solution, and SPA signals were detected by a MicroBeta scintillation counter. No separation step is needed, which simplifies the assay procedure and greatly enhances the assay speed. Particularly, the miniaturization and robustness suggest that this method is suited for HTS of PRMT inhibitors. PMID:21821785

Wu, Jiang; Xie, Nan; Feng, You; Zheng, Y George

2012-02-01

129

Extruded Plastic Scintillator for the Minos Calorimeters.  

National Technical Information Service (NTIS)

MINOS is a long-baseline, neutrino-oscillation experiment. Two iron- and scintillator-calorimeters will be built, requiring almost 300 tons of finished plastic scintillator. In order to lower the scintillator costs, MINOS will use an extruded rectangular ...

A. Pla-Dalmau

2001-01-01

130

The Monte-Carlo simulation on a scintillator neutron detector  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

131

Properties of new scintillation glasses and scintillating fibers  

SciTech Connect

The authors present data on the light output and optical properties of new scintillation glasses. Data on light (rho approx. = 2.6g/cm/sup 3/) and heavy (rho > 3.4g/cm/sup 3/) glasses are presented. In addition, the performance of scintillating glass fibers fabricated using a new light glass is discussed.

Bross, A.D.

1986-02-01

132

Properties of New Scintillation Glasses and Scintillating Fibers  

Microsoft Academic Search

We present data on the light output and optical properties of new scintillation glasses. Data on light (¿ ¿ 2.6g\\/cm3) and heavy (¿ > 3.4g\\/cm3) glasses are presented. In addition, the performance of scintillating glass fibers fabricated using a new light glass is discussed.

Alan D. Bross

1986-01-01

133

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

Microsoft Academic Search

A clinical prototype of a scintillating fiber dosimeter array for quality assurance applications is presented. The array consists of a linear array of 29 plastic scintillation detectors embedded in a water-equivalent plastic sheet coupled to optical fibers used to guide optical photons to a charge coupled device (CCD) camera. The CCD is packaged in a light-tight, radiation-shielded housing designed for

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

2008-01-01

134

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

Microsoft Academic Search

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

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

1967-01-01

135

Well-type scintillation assembly  

Microsoft Academic Search

A scintillation detector assembly is described which employs a scintillation phosphor such as a thallium activated sodium iodide crystal, wherein a blind hole is machined in the crystal to improve the efficiency of measuring the degradation rate of a radioactive material placed therein. The performance of the assembly is defined by the energy resolution of the radiation emanating from the

M. R. Farukhi; G. A. Mataraza; O. D. Wimer

1978-01-01

136

New Cerium Activated Scintillating Glasses  

Microsoft Academic Search

The synthesis of cerium activated scintillating glasses is being continued, and two new types have been developed. One of these, a magnesium aluminum borate, is similar to the alkali borate glasses reported previously and was made in an effort to provide a scintillating glass with the highest possible boron content in which a reasonable pulse height could be retained. Its

Robert J. Ginther

1960-01-01

137

STUDY ON SOME SCINTILLATING GLASSES  

Microsoft Academic Search

Scintillation properties of lithium borosilicate cerium activated ; glasses are considered. Measurements of transmittance, excitation, fluorescence ; spectra, and pulse height distribution under thermal neutron irradiation are ; reported along with some considerations on the influence of BâOâ ; content on the scintillation properties. (auth);

G. Bertozzi; C. Coeceva; S. Pizzini

1962-01-01

138

Scintillation detector for carbon-14  

NASA Technical Reports Server (NTRS)

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

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

1971-01-01

139

Lithium-loaded liquid scintillators  

DOEpatents

The invention is directed to a liquid scintillating composition containing (i) one or more non-polar organic solvents; (ii) (lithium-6)-containing nanoparticles having a size of up to 10 nm and surface-capped by hydrophobic molecules; and (iii) one or more fluorophores. The invention is also directed to a liquid scintillator containing the above composition.

Dai, Sheng (Knoxville, TN); Kesanli, Banu (Mersin, TR); Neal, John S. (Knoxville, TN)

2012-05-15

140

Equatorial scintillation and systems support  

Microsoft Academic Search

The need to nowcast and forecast scintillation for the support of operational systems has been recently identified by the interagency National Space Weather Program. This issue is addressed in the present paper in the context of nighttime irregularities in the equatorial ionosphere that cause intense amplitude and phase scintillations of satellite signals in the VHF\\/UHF range of frequencies and impact

S. Basu; E. J. Weber; M. Smitham; H. Kuenzler; C. E. Valladares; R. Sheehan; E. MacKenzie; J. A. Secan; P. Ning; W. J. McNeill; D. W. Moonan; M. J. Kendra

1997-01-01

141

Development of radiation hard scintillators  

SciTech Connect

The authors have demonstrated that the radiation stability of scintillators made from styrene polymer is very much improved by compounding with pentaphenyltrimethyltrisiloxane (DC 705 vacuum pump oil). The resulting scintillators are softer than desired, so they decided to make the scintillators directly from monomer where the base resin could be easily crosslinked to improve the mechanical properties. They can now demonstrate that scintillators made directly from the monomer, using both styrene and 4-methyl styrene, are also much more radiation resistant when modified with DC705 oil. In fact, they retain from 92% to 95% of their original light output after gamma irradiation to 10 Mrads in nitrogen with air annealing. When these scintillators made directly from monomer are compared with scintillators of the same composition made from polymer the latter have much higher light outputs. They commonly reach 83% while those made form monomer give only 50% to 60% relative to the reference, BC408. When oil modified scintillators using both p-terphenyl and tetraphenylbutadiene are compared with identical scintillators except that they use 3 hydroxy-flavone as the only luminophore the radiation stability is the same. However the 3HF system gives only 30% as much light as BC408 instead of 83% when both are measured with a green extended Phillips XP2081B phototube.

Markley, F.; Davidson, M.; Keller, J.; Foster, G.; Pla-Dalmau, A. [Fermi National Accelerator Lab., Batavia, IL (United States); Harmon, J.; Biagtan, E.; Schueneman, G. [Univ. of Florida, Gainesville, FL (United States). Physics Dept.; Senchishin, V. [Inst. for Single Crystals, Kharkov (Ukraine); Gustfason, H.; Rivard, M. [Univ. of Michigan, Ann Arbor, MI (United States)

1993-11-01

142

EISCAT measurements of interplanetary scintillation  

Microsoft Academic Search

EISCAT has been used to make three types of measurement of the characteristics of the solar wind in the range 10–120 solar radii. The rms fluctuation in the total power received from a single source can be measured to provide a `scintillation index'. The cross-correlation of the scintillations observed at two sites can be used to measure the velocity of

A. R. Breen; W. A. Coles; R. Grall; U.-P. Levhaug; J. Markkanen; H. Misawas; P. J. S. Williams

1996-01-01

143

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

PubMed

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

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

2014-02-01

144

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

Microsoft Academic Search

Digital X-ray imaging detectors designed for soft X-rays (1 to 50 keV) are significant for medical mammography, dental radiography, microradiography, and microtomography. Detector designs involve either direct absorption of X-rays in solid state devices or thin scintillator screens optically coupled to solid state sensors. Well designed scintillator systems produce 10 or more electrons per detected X-ray and, used with charge

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

1995-01-01

145

Rare earth phosphors and phosphor screens  

DOEpatents

This invention relates to rare earth phosphor screens for converting image carrying incident radiation to image carrying visible or near-visible radiation and to the rare earth phosphor materials utilized in such screens. The invention further relates to methods for converting image carrying charged particles to image carrying radiation principally in the blue and near-ultraviolet region of the spectrum and to stabilized rare earth phosphors characterized by having a continuous surface layer of the phosphors of the invention. More particularly, the phosphors of the invention are oxychlorides and oxybromides of yttrium, lanthanum and gadolinium activated with trivalent cerium and the conversion screens are of the type illustratively including x-ray conversion screens, image amplifier tube screens, neutron imaging screens, cathode ray tube screens, high energy gamma ray screens, scintillation detector screens and screens for real-time translation of image carrying high energy radiation to image carrying visible or near-visible radiation.

Buchanan, Robert A. (Palo Alto, CA); Maple, T. Grant (Sunnyvale, CA); Sklensky, Alden F. (Sunnyvale, CA)

1981-01-01

146

Scintillating optical fiber trajectory detectors  

NASA Astrophysics Data System (ADS)

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

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

1989-03-01

147

Proton recoil scintillator neutron rem meter  

DOEpatents

A neutron rem meter utilizing proton recoil and thermal neutron scintillators to provide neutron detection and dose measurement. In using both fast scintillators and a thermal neutron scintillator the meter provides a wide range of sensitivity, uniform directional response, and uniform dose response. The scintillators output light to a photomultiplier tube that produces an electrical signal to an external neutron counter.

Olsher, Richard H. (Los Alamos, NM); Seagraves, David T. (Los Alamos, NM)

2003-01-01

148

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

149

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

150

Properties of scintillator solutes  

SciTech Connect

This special report summarizes measurements of the spectroscopic and other properties of the solutes that were used in the preparation of several new liquid scintillators developed at EG and G/Energy Measurements/Santa Barbara Operations (the precursor to Bechtel Nevada/Special Technologies Laboratory) on the radiation-to-light converter program. The data on the individual compounds are presented in a form similar to that used by Prof. Isadore Berlman in his classic handbook of fluorescence spectra. The temporal properties and relative efficiencies of the new scintillators are presented in Table 1, and the efficiencies as a function of wavelength are presented graphically in Figure 1. In addition, there is a descriptive glossary of the abbreviations used herein. Figure 2 illustrates the basic structures of some of the compounds and of the four solvents reported in this summary. The emission spectra generally exhibit more structure than the absorption spectra, with the result that the peak emission wavelength for a given compound may lie several nm away from the wavelength, {lambda}{sub avg}, at the geometric center of the emission spectrum. Therefore, the author has chosen to list absorption peaks, {lambda}{sub max}, and emission {lambda}{sub avg} values in Figures 3--30, as being most illustrative of the differences between the compounds. The compounds, BHTP, BTPB, ADBT, and DPTPB were all developed on this program. P-terphenyl, PBD, and TPB are commercially available blue emitters. C-480 and the other longer-wavelength emitters are laser dyes available commercially from Exciton Corporation. 1 ref., 30 figs.

Fluornoy, J.M.

1998-06-01

151

Refractive interstellar scintillation effects in pulsar observations  

SciTech Connect

Propagation of radio waves through the interstellar medium (ISM) produces fluctuations in the obsered intensity of a source because of the scattering caused by the irregular electron density distribution in the interstellar plasma. Under conditions of strong scintillations, the intensity fluctuations produced exhibit two predominant scales - the small scale (diffractive) fluctuations which are modulated by the large scale (refractive) fluctuations. Several aspects of the effect of refractive interstellar scintillation (RISS) in pulsar data are investigated. The results help to constrain the power spectrum of electron density fluctuations in the ISM. Some of these aspects of RISS are tested using numerical simulations of the scattering from a thin screen, for moderate ({approx}20) values of strength of scattering (U). The refractive models are not found to work as well as for the real data. Long-term fluctuations of nine pulsars were observed for fourteen months at 74 MHz using the Fallbrook antenna. The inferred modulation indices (or lower bounds thereof) for many of these pulsars are found to be higher than those predicted by the simple Kolmogorov spectrum, supporting an inner scale of the order of 10{sup 7} - 10{sup 8} m.

Gupta, Y.

1990-01-01

152

Guide for Conducting Treatability Studies under CERCLA.  

National Technical Information Service (NTIS)

The guide describes an approach for conducting treatability studies that consists of laboratory screening, bench-scale testing, and pilot-scale testing. The guide also presents a stepwise approach or protocol for conducting treatability studies for determ...

1989-01-01

153

Probability Distribution of Irradiance Scintillation.  

National Technical Information Service (NTIS)

We calculated the probability distribution function (PDF) from simulations. The simulations were of an initially spherical wave propagated through homogeneous atmospheric turbulence. The onset of strong scintillation was calculated. The simulations' PDFs ...

R. J. Hill R. G. Frehlich W. D. Otto

1997-01-01

154

Scintillating glass fiber neutron sensors.  

National Technical Information Service (NTIS)

Cerium-doped lithium-silicate glass fibers have been developed at Pacific Northwest Laboratory (PNL) for use as thermal neutron detectors. By using highly-enriched (sup 6) Li , these fibers efficiently capture thermal neutrons and produce scintillation li...

K. H. Abel R. J. Arthur M. Bliss

1994-01-01

155

Development of intrinsic IPT scintillator.  

National Technical Information Service (NTIS)

We report on the development of a new polystyrene based plastic scintillator. Optical absorption, fluorescence and light output measurements are presented. Preliminary results of radiation damage effects are also given and compared to the effects on a com...

A. D. Bross

1989-01-01

156

Scintillator fiber optic long counter  

DOEpatents

A flat response position sensitive neutron detector capable of providing neutron spectroscopic data utilizing scintillator fiber optic filaments embedded in a neutron moderating housing having an open end through which neutrons enter to be detected.

McCollum, Tom (Sterling, VA); Spector, Garry B. (Fairfax, VA)

1994-01-01

157

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

SciTech Connect

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

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

2007-07-01

158

About NICADD extruded scintillating strips  

SciTech Connect

The results of control measurements of extruded scintillating strip responses to a radioactive source Sr-90 are provided, and details of strip choice, preparation, and method of measurement are included. About four hundred one meter long extruded scintillating strips were measured at four different points. These results were essential for prototyping a tail catcher and muon tracker for a future international electron positron linear collider detector.

Dyshkant, A.; Beznosko, D.; Blazey, G.; Chakraborty, D.; Francis, K.; Kubik, D.; Lima, J.G.; Rykalin, V.; Zutshi, v.; /Northern Illinois U.; Baldina, E.; Bross, A.; Deering, P.; Nebel, T.; Pla-Dalmau, A.; Schellpfeffer, J.; Serritella, C.; Zimmerman, J.; /Fermilab

2005-04-01

159

Scintillating glass fiber neutron senors  

Microsoft Academic Search

Cerium-doped lithium-silicate glass fibers have been developed at Pacific Northwest Laboratory (PNL) for use as thermal neutron detectors. By using highly-enriched ⁶ Li , these fibers efficiently capture thermal neutrons and produce scintillation light that can be detected at the ends of the fibers. Advantages of scintillating fibers over ³He or BFâ proportional tubes include flexibility in geometric configuration, ruggedness

K. H. Abel; R. J. Arthur; M. Bliss; D BRITE; R BRODZINSKI; R CRAIG; B GEELHOOD; D GOLDMAN; J GRIFFIN; R PERKINS

1994-01-01

160

New low cost acrylic scintillators  

NASA Astrophysics Data System (ADS)

We have developed a variety of new acrylic scintillators. One of them is to be used in calorimetry in combination with the wavelength shifter bar technique and the others in a more classical way, directly coupled to photomulitpliers. Their common characteristic is a high light output together with a low cost. We present the mechanical and opitcal properties of these scintillators and compare them with some commonly used existing ones.

Aurouet, C.; Blumenfeld, H.; Bosc, G.; Bourdinaud, M.; Evrard, P.; Jeanney, C.; Lafond, C.

1980-02-01

161

Razdelenie ehlektronov i adronov v yacheistom ehlektromagnitnom kalorimetre tipa sehdwich svinets-stsintillyator. (Electron and hadron discrimination in cell electromagnetic calorimeter of lead-scintillator sandwich type).  

National Technical Information Service (NTIS)

Additional light-guide-shifter which collects light only from scintillation plates arranged in maximum of electromagnetic shower is suggested to use to improve efficiency of electron and hadron separation in the module of hodoscopic detector GEPARD. Using...

Y. Ivanyushkin E. Kistenev V. M. Kubik Y. Pishchal'nikov A. G. Kholodenko

1988-01-01

162

Lunar components in Lunping scintillations  

NASA Astrophysics Data System (ADS)

Fourteen consecutive years of 15-min scintillation index values observed in Lunping, Taiwan have been analyzed by the lunar age superposition method. Analysis covers 24 hrs/day and is performed separately for each of the four seasons. Statistically significant first and second lunar harmonics have been found at all seasons, but the largest and most significant occur in the summertime data. During the daytime the probability of scintillations at Lunping is significantly correlated with f(0)E(s). We conclude that our lunar harmonics probably result from the modulation, in the E region, of neutral winds of solar thermal origin by upward propagating lunar tides. The nighttime scintillations are larger and tidal neutral air velocities seem to play a role in the production mechanism(s). There is clear evidence for both the summertime temperate latitude type of scintillations observed in Japan and the scintillations, mainly equinoctial, arising from the equatorial bubble mechanism. Four distinct statistically significant summertime scintillation periods are found, plus one each in the autumnal and winter data. An attempt is made to identify the production mechanism associated with each.

Koster, John R.; Huang, Yinn-Nien; Lue, H. Y.; Wu, Hsi-Shu

1993-08-01

163

Evaluation of a high-density scintillating glass for portal imaging.  

PubMed

One of the main factors that limits the performance of T.V. camera-based portal imaging systems is the poor light-collection efficiency of the lens and T.V. camera. An x-ray detector that produces more light per incident x ray would help overcome this limitation. We have been evaluating a high-density (3.8 g/cm3), thick (12 mm) glass scintillator for its suitability as an x-ray detector for T.V. camera-based portal imaging systems. The light output and spatial resolution of the glass scintillator has been compared to that of a copper plate/phosphor screen detector using radiographic film and the T.V. camera of our portal imaging system. The film measurements show that the light output of the glass scintillator is 82% of that of the copper plate/phosphor screen, while the T.V. camera measurements show that this value is 48%. A theoretical model of light transport described in this paper suggests that this discrepancy is due to refraction at the glass-air interface. Our measurements of the modulation transfer function (MTF) show that the spatial resolution obtained with the glass scintillator is similar to that obtained with the copper plate phosphor screen. However, the spatial resolution obtained with the glass scintillator decreases as the angle of x-ray incidence increase; this decrease, which is not observed for the copper plate/phosphor screen detector, is due to the large thickness of the glass scintillator. Due to the limited light output and the variable spatial resolution, the transparent glass scintillator, in its current form, is not suitable for portal imaging. PMID:8815383

Bissonnette, J P; Munro, P

1996-03-01

164

Response of liquid scintillator assemblies as a function of angular orientation  

NASA Astrophysics Data System (ADS)

Liquid scintillator detector assemblies contain an inert nitrogen expansion volume to allow for expansion of the liquid with changing temperature. Measurements and Geant4 Monte Carlo simulations are performed to study the dependence of pulse height distribution shapes as a function of detector angle for two liquid scintillators assemblies filled with 97% organic-liquid cocktail and a 3% expansion volume. A 12.7-cm diameter by 12.7-cm long and a 7.6-cm diameter by 9.1-cm long EJ-309 liquid scintillator assemblies are investigated using a 137Cs gamma-ray source. Aside from the differences in dimensions, the detector assemblies also differed in the design of the active detector volume: there is no light guide in the 12.7-cm-diameter detector assembly, whereas the 7.6-cm-diameter detector contains a BK7 light guide between the scintillation liquid and optical coupling to the photomultiplier tube. Results for the 12.7-cm-diameter detector show a decrease in the position of the Compton edge ranges from 4% to 40% at detector orientations where the expansion volume exists between scintillating medium and the photomultiplier tube. Results for the 7.6-cm-diameter detector show that the position of the Compton edge is relatively unaffected at all detector orientations due to the presence of light guide.

Naeem, S. F.; Scarpelli, M.; Miller, E.; Clarke, S. D.; Pozzi, S. A.

2014-06-01

165

A theoretical model evaluating the angular distribution of luminescence emission in X-ray scintillating screens I. Kandarakisa,, D. Cavourasa, D. Nikolopoulosa, A. Episkopakisa, N. Kalivasb, P. Liaparinosc, I. Valaisa, G. Kagadisc, K. Kourkoutasd, I. Sianoudisd, N. Dimitropoulose, C. Nomicosf, G. Panayiotakisc  

Microsoft Academic Search

The aim of this study was to examine the angular distribution of the light emitted from radiation-excited scintillators in medical imaging detectors. This distribution diverges from Lambert's cosine law and affects the light emission efficiency of scintillators, hence it also affects the dose burden to the patient. In the present study, the angular distribution was theoretically modeled and was used

Agiou Spyridonos

166

Dealing with Cerenkov radiation generated in organic scintillator dosimeters by bremsstrahlung beams  

NASA Astrophysics Data System (ADS)

An organic scintillator detector system has been developed for radiotherapy bremsstrahlung dosimetry. The scintillators are connected to photodiodes by light pipes as the photodiodes must be removed and shielded from the incident radiation. The photodiodes see visible and near-visible light emissions from the scintillator as well as Cerenkov and fluorescence radiation that has been generated and trapped in the scintillator and light pipe. The Cerenkov and fluorescence radiation limits the accuracy of the dosimeter. This work examines a range of methods for diminishing the signal contribution of Cerenkov and fluorescence radiation while optimizing the scintillator signal. Three methods of achieving these goals have been used. They are: reflective coatings on the scintillator, long-wavelength-emitting scintillators used in conjunction with the photodiode, and absorptive filters placed between the light guide and photodiode. The contribution of the Cerenkov radiation to the light seen by the photodiode has been modelled and the model predictions have been tested using bremsstrahlung beams of peak energy between 13 and 20 MV, showing agreement with measurement.

Clift, M. A.; Sutton, R. A.; Webb, D. V.

2000-05-01

167

Dealing with Cerenkov radiation generated in organic scintillator dosimeters by bremsstrahlung beams.  

PubMed

An organic scintillator detector system has been developed for radiotherapy bremsstrahlung dosimetry. The scintillators are connected to photodiodes by light pipes as the photodiodes must be removed and shielded from the incident radiation. The photodiodes see visible and near-visible light emissions from the scintillator as well as Cerenkov and fluorescence radiation that has been generated and trapped in the scintillator and light pipe. The Cerenkov and fluorescence radiation limits the accuracy of the dosimeter. This work examines a range of methods for diminishing the signal contribution of Cerenkov and fluorescence radiation while optimizing the scintillator signal. Three methods of achieving these goals have been used. They are: reflective coatings on the scintillator, long-wavelength-emitting scintillators used in conjunction with the photodiode, and absorptive filters placed between the light guide and photodiode. The contribution of the Cerenkov radiation to the light seen by the photodiode has been modelled and the model predictions have been tested using bremsstrahlung beams of peak energy between 13 and 20 MV, showing agreement with measurement. PMID:10843098

Clift, M A; Sutton, R A; Webb, D V

2000-05-01

168

Structural design of a high energy particle detector using liquid scintillator  

SciTech Connect

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

Berg, Timothy John; /Minnesota U.

1997-02-01

169

Plastic scintillation dosimetry: comparison of three solutions for the Cerenkov challenge.  

PubMed

In scintillation dosimetry, a Cerenkov background signal is generated when a conventional fibre optic is exposed to radiation produced by a megavoltage linear accelerator. Three methods of measuring dose in the presence of Cerenkov background are compared. In the first method, a second background fibre is used to estimate the Cerenkov signal in the signal fibre. In the second method, a colour camera is used to measure the combined scintillation and Cerenkov light in two wavelength ranges and a mathematical process is used to extract the scintillation signal. In the third method, a hollow air core light guide is used to carry the scintillation signal through the primary radiation field. In this paper, the strengths and weaknesses of each dosimetry system are identified and recommendations for the optimum method for common clinical dosimetry situations are made. PMID:21846934

Liu, P Z Y; Suchowerska, N; Lambert, J; Abolfathi, P; McKenzie, D R

2011-09-21

170

Low-Dose Megavoltage Cone-Beam CT imaging using Thick, Segmented Scintillators  

PubMed Central

Megavoltage, cone-beam computed tomography (MV CBCT) employing an electronic portal imaging device (EPID) is a highly promising technique for providing soft-tissue visualization in image-guided radiotherapy. However, current EPIDs based on active matrix flat-panel imagers (AMFPIs), which are regarded as the gold standard for portal imaging and referred to as conventional MV AMFPIs, require high radiation doses to achieve this goal due to poor x-ray detection efficiency (~2% at 6 MV). To overcome this limitation, the incorporation of thick, segmented, crystalline scintillators, as a replacement for the phosphor screens used in these AMFPIs, has been shown to significantly improve the DQE performance, leading to improved image quality for projection imaging at low dose. Toward the realization of practical AMFPIs capable of low dose, soft-tissue visualization using MV CBCT imaging, two prototype AMFPIs incorporating segmented scintillators with ~11 mm thick CsI:Tl and BGO crystals were evaluated. Each scintillator consists of 120 × 60 crystalline elements separated by reflective septal walls, with an element-to-element pitch of 1.016 mm. The prototypes were evaluated using a bench-top CBCT system, allowing the acquisition of 180 projection, 360° tomographic scans with a 6 MV radiotherapy photon beam. Reconstructed images of a spatial resolution phantom, as well as of a water-equivalent phantom, embedded with tissue equivalent objects having electron densities (relative to water) varying from ~0.28 to ~1.70, were obtained down to one beam pulse per projection image, corresponding to a scan dose of ~4 cGy – a dose similar to that required for a single portal image obtained from a conventional MV AMFPI. By virtue of their significantly improved DQE, the prototypes provided low contrast visualization, allowing clear delineation of an object with an electron density difference of ~2.76%. Results of contrast, noise and contrast-to-noise ratio are presented as a function of dose and compared to those from a conventional MV AMFPI.

El-Mohri, Youcef; Antonuk, Larry E.; Zhao, Qihua; Choroszucha, Richard B.; Jiang, Hao; Liu, Langechuan

2011-01-01

171

Low-dose megavoltage cone-beam CT imaging using thick, segmented scintillators.  

PubMed

Megavoltage, cone-beam computed tomography (MV CBCT) employing an electronic portal imaging device (EPID) is a highly promising technique for providing soft-tissue visualization in image-guided radiotherapy. However, current EPIDs based on active matrix flat-panel imagers (AMFPIs), which are regarded as the gold standard for portal imaging and referred to as conventional MV AMFPIs, require high radiation doses to achieve this goal due to poor x-ray detection efficiency (?2% at 6 MV). To overcome this limitation, the incorporation of thick, segmented, crystalline scintillators, as a replacement for the phosphor screens used in these AMFPIs, has been shown to significantly improve the detective quantum efficiency (DQE) performance, leading to improved image quality for projection imaging at low dose. Toward the realization of practical AMFPIs capable of low dose, soft-tissue visualization using MV CBCT imaging, two prototype AMFPIs incorporating segmented scintillators with ?11 mm thick CsI:Tl and Bi(4)Ge(3)O(12) (BGO) crystals were evaluated. Each scintillator consists of 120 × 60 crystalline elements separated by reflective septal walls, with an element-to-element pitch of 1.016 mm. The prototypes were evaluated using a bench-top CBCT system, allowing the acquisition of 180 projection, 360° tomographic scans with a 6 MV radiotherapy photon beam. Reconstructed images of a spatial resolution phantom, as well as of a water-equivalent phantom, embedded with tissue equivalent objects having electron densities (relative to water) varying from ?0.28 to ?1.70, were obtained down to one beam pulse per projection image, corresponding to a scan dose of ?4 cGy--a dose similar to that required for a single portal image obtained from a conventional MV AMFPI. By virtue of their significantly improved DQE, the prototypes provided low contrast visualization, allowing clear delineation of an object with an electron density difference of ?2.76%. Results of contrast, noise and contrast-to-noise ratio are presented as a function of dose and compared to those from a conventional MV AMFPI. PMID:21325709

El-Mohri, Youcef; Antonuk, Larry E; Zhao, Qihua; Choroszucha, Richard B; Jiang, Hao; Liu, Langechuan

2011-03-21

172

High resolution time-of-flight measurements in small and large scintillation counters  

NASA Astrophysics Data System (ADS)

In a test run, the experimental time-of-flight resolution was measured for several different scintillation counters of small (10 × 5 cm 2) and large (100 × 15 cm 2 and 75 × 25 cm 2) area. The design characteristics were decided on the basis of theoretical Monte Carlo calculations. We report results using twisted, fish-tail, and rectangular light-guides and different types of scintillator (NE114 and PILOT U). Time resolution up to ˜130-150 ps fwhm for the small counters and up to ˜280-300 ps fwhm for the large counters were obtained. The spatial resolution from time measurements in the large counters is also reported. The results of Monte Carlo calculations on the type of scintillator, the shape and dimensions of the light-guides, and the nature of the external wrapping surfaces — to be used in order to optimize the time resolution — are also summarized.

D'Agostini, G.; Marini, G.; Martellotti, G.; Massa, F.; Rambaldi, A.; Sciubba, A.

173

VHF scintillations as a diagnostic tool for the study of ionospheric irregularities  

NASA Astrophysics Data System (ADS)

In this paper we present the results of observations of the scintillations of radio beacon on 250.351 MHz from geostationary satellite FLEETSAT (73 deg E) recorded at Bombay on April 9-10, 1992 during night hours. The scintillation index, S(sub 4), is used to describe the strength of the scintillations. The variation of scintillation index with local time shows a maxima of 0.589 at 02:55 India Standard Time (IST). This scintillation activity is linked with the spread F-irregularities. A brief description of the scintillation theories like phase screen theory and theory for weak scintillations -- Rytov solution is given. These theories provide an integral measure of the fluctuations in terms of phase and amplitude fluctuations imposed on VHF signals while traversing through the ionosphere. Power spectrum analysis for the log-amplitude and phase departure and cross spectrum between them have also been carried out. Using spectral index p = 1, we have shown that the scale sizes for the ionospheric irregularities are greater than 1 km.

Ahmad, Altaf; Ahmad, M. M.; Pathan, B. M.

1994-01-01

174

An imaging technique for detection and absolute calibration of scintillation light  

SciTech Connect

Triggered by the need of a detection system to be used in experiments of nuclear fusion in laser-generated plasmas, we developed an imaging technique for the measurement and calibration of the scintillation light yield of scintillating materials. As in such experiments, all the reaction products are generated in an ultrashort time frame, the event-by-event data acquisition scheme is not feasible. As an alternative to the emulsion technique (or the equivalent CR39 sheets) we propose a scintillating screen readout by means of a high performance charge coupled device camera. Even though it is not strictly required in the particular application, this technique allows the absolute calibration of the scintillation light yield.

Pappalardo, Alfio; Cosentino, Luigi; Finocchiaro, Paolo [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, 95125 Catania (Italy)

2010-03-15

175

An imaging technique for detection and absolute calibration of scintillation light.  

PubMed

Triggered by the need of a detection system to be used in experiments of nuclear fusion in laser-generated plasmas, we developed an imaging technique for the measurement and calibration of the scintillation light yield of scintillating materials. As in such experiments, all the reaction products are generated in an ultrashort time frame, the event-by-event data acquisition scheme is not feasible. As an alternative to the emulsion technique (or the equivalent CR39 sheets) we propose a scintillating screen readout by means of a high performance charge coupled device camera. Even though it is not strictly required in the particular application, this technique allows the absolute calibration of the scintillation light yield. PMID:20370171

Pappalardo, Alfio; Cosentino, Luigi; Finocchiaro, Paolo

2010-03-01

176

Application of small inexpensive side-on (side-window) photomultiplier tubes for scintillating fiber readout  

Microsoft Academic Search

Small inexpensive side-on photomultiplier tubes (PMTs) with excellent characteristics were tested for scintillating fiber readout. The location of the photocathode and nonuniform response of the photomultiplier poses problems in fiber or light guide readout. To overcome these problems the authors have devised and tested a fiber to PMT coupling technique which partially collimates the cone of light exciting a fiber

Andrew Weisenberger; Brian Kross; Stan Majewski; Randy Wojcik; Carl Zorn

1992-01-01

177

FNAL-NICADD extruded scintillator  

SciTech Connect

The possibility to produce a scintillator that satisfies the demands of physicists from different science areas has emerged with the installation of an extrusion line at Fermi National Accelerator Laboratory (FNAL). The extruder is the product of the fruitful collaboration between FNAL and Northern Illinois Center for Accelerator and Detector Development (NICADD) at Northern Illinois University (NIU). The results from the light output, light attenuation length and mechanical tolerance indicate that FNAL-NICADD scintillator is of high quality. Improvements in the extrusion die will yield better scintillator profiles and decrease the time needed for initial tuning. This paper will present the characteristics of the FNAL-NICADD scintillator based on the measurements performed. They include the response to MIPs from cosmic rays for individual extruded strips and irradiation studies where extruded samples were irradiated up to 1 Mrad. We will also discuss the results achieved with a new die design. The attractive perspective of using the extruded scintillator with MRS (Metal Resistive Semiconductor) photodetector readout will also be shown.

Beznosko, D.; /Northern Illinois U.; Bross, A.; /Fermilab; Dyshkant, A.; /Northern Illinois U.; Pla-Dalmau, A.; /Fermilab; Rykalin, V.; /Northern Illinois U.

2005-09-01

178

Scintillating glass fiber neutron senors  

SciTech Connect

Cerium-doped lithium-silicate glass fibers have been developed at Pacific Northwest Laboratory (PNL) for use as thermal neutron detectors. By using highly-enriched {sup 6} Li , these fibers efficiently capture thermal neutrons and produce scintillation light that can be detected at the ends of the fibers. Advantages of scintillating fibers over {sup 3}He or BF{sub 3} proportional tubes include flexibility in geometric configuration, ruggedness in high-vibration environments, and less detector weight for the same neutron sensitivity. This paper describes the performance of these scintillating fibers with regard to count rates, pulse height spectra, absolute efficiencies, and neutron/gamma discrimination. Fibers with light transmission lengths (1/e) of greater than 2 m have been produced at PNL. Neutron sensors in fiber form allow development of a variety of neutron detectors packaged in previously unavailable configurations. Brief descriptions of some of the devices already produced are included to illustrate these possibilities.

Abel, K.H.; Arthur, R.J.; Bliss, M.

1994-04-01

179

Unitary scintillation detector and system  

DOEpatents

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

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

1994-01-01

180

Unitary scintillation detector and system  

DOEpatents

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

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

1994-05-31

181

Fracture-resistant lanthanide scintillators  

DOEpatents

Lanthanide halide alloys have recently enabled scintillating gamma ray spectrometers comparable to room temperature semiconductors (<3% FWHM energy resolutions at 662 keV). However brittle fracture of these materials upon cooling hinders the growth of large volume crystals. Efforts to improve the strength through non-lanthanide alloy substitution, while preserving scintillation, have been demonstrated. Isovalent alloys having nominal compositions of comprising Al, Ga, Sc, Y, and In dopants as well as aliovalent alloys comprising Ca, Sr, Zr, Hf, Zn, and Pb dopants were prepared. All of these alloys exhibit bright fluorescence under UV excitation, with varying shifts in the spectral peaks and intensities relative to pure CeBr.sub.3. Further, these alloys scintillate when coupled to a photomultiplier tube (PMT) and exposed to .sup.137Cs gamma rays.

Doty, F. Patrick (Livermore, CA)

2011-01-04

182

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

2010-03-16

183

Distributed feedback lasing of commercial liquid scintillators.  

PubMed

It is shown that lasing can be achieved in commercial organic liquid scintillators. Using a dynamic grating induced by an interference pattern in the scintillator volume, distributed feedback lasing is shown to occur in four out of five commercial liquid scintillators that have been investigated. Although these scintillators are not designed for lasing application, their purpose being to measure radioactivity, induction of a laser effect, furthermore with a tuning range of approximately 30 nm, has been attained. PMID:24322244

Michel, Maugan; Rocha, Licinio; Hamel, Matthieu; Normand, Stéphane; Angélique, Jean-Claude

2013-12-15

184

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

185

Theory of anisotropic refractive scintillation - Application to stellar occultations by Neptune  

NASA Technical Reports Server (NTRS)

A theory of refractive scintillation due to a thin phase-changing screen with an anisotropic power-law spectrum of phase fluctuations is presented. Scintillation theory for an isotropic medium is discussed, and anisotropy of the mean density and anisotropy in the scattering are discussed. The theory of refractive scintillation in an anisotropic medium is developed, deriving a general expression for the cross-correlation of flux variations at two points on the 'observer screen'. From this, estimates of the coherence lengths and amplitudes of flux variations are obtained for important parameter regimes. The application of the theory to the analysis of two occultations by Neptune is addressed. The projected dimensions of the occulting stars, a normalization constant to describe the phase fluctuations, and an anisotropy parameter are determined, and the theory is shown to agree well with observation. The significance of the theory for understanding of the physics of Neptune's atmosphere is discussed.

Narayan, Ramesh; Hubbard, W. B.

1988-01-01

186

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

187

Ionospheric scintillation effects on single frequency GPS  

Microsoft Academic Search

Ionospheric scintillation of Global Positioning System (GPS) signals threatens navigation and military operations by degrading performance or making GPS unavailable. Scintillation is particularly active within, although not limited to, a belt encircling the Earth within 20 degrees of the geomagnetic equator. As GPS applications and users increase, so does the potential for degraded precision and availability from scintillation. We examined

R. A. Steenburgh; C. G. Smithtro; K. M. Groves

2008-01-01

188

Characteristics of High Latitude Ionosphere Scintillations  

NASA Astrophysics Data System (ADS)

As we enter a new solar maximum period, global navigation satellite systems (GNSS) receivers, especially the ones operating in high latitude and equatorial regions, are facing an increasing threat from ionosphere scintillations. The increased solar activities, however, also offer a great opportunity to collect scintillation data to characterize scintillation signal parameters and ionosphere irregularities. While there are numerous GPS receivers deployed around the globe to monitor ionosphere scintillations, most of them are commercial receivers whose signal processing mechanisms are not designed to operate under ionosphere scintillation. As a result, they may distort scintillation signal parameters or lose lock of satellite signals under strong scintillations. Since 2008, we have established and continuously improved a unique GNSS receiver array at HAARP, Alaska. The array contains high ends commercial receivers and custom RF front ends which can be automatically triggered to collect high quality GPS and GLONASS satellite signals during controlled heating experiments and natural scintillation events. Custom designed receiver signal tracking algorithms aim to preserve true scintillation signatures are used to process the raw RF samples. Signal strength, carrier phase, and relative TEC measurements generated by the receiver array since its inception have been analyzed to characterize high latitude scintillation phenomena. Daily, seasonal, and solar events dependency of scintillation occurrence, spectral contents of scintillation activities, and plasma drifts derived from these measurements will be presented. These interesting results demonstrate the feasibility and effectiveness of our experimental data collection system in providing insightful details of ionosphere responses to active perturbations and natural disturbances.

Morton, Y.

2012-12-01

189

Composite scintillators for detection of ionizing radiation  

DOEpatents

Applicant's present invention is a composite scintillator having enhanced transparency for detecting ionizing radiation comprising a material having optical transparency wherein said material comprises nano-sized objects having a size in at least one dimension that is less than the wavelength of light emitted by the composite scintillator wherein the composite scintillator is designed to have selected properties suitable for a particular application.

Dai, Sheng (Knoxville, TN) [Knoxville, TN; Stephan, Andrew Curtis (Knoxville, TN) [Knoxville, TN; Brown, Suree S. (Knoxville, TN) [Knoxville, TN; Wallace, Steven A. (Knoxville, TN) [Knoxville, TN; Rondinone, Adam J [Knoxville, TN

2010-12-28

190

Synthesis of plastic scintillation microspheres: Evaluation of scintillators  

NASA Astrophysics Data System (ADS)

The use of plastic scintillation microspheres (PSm) appear to be an alternative to liquid scintillation for the quantification of alpha and beta emitters because it does not generate mixed wastes after the measurement (organic and radioactive). In addition to routine radionuclide determinations, PSm can be used for further applications, e.g. for usage in a continuous monitoring equipment, for measurements of samples with a high salt concentration and for an extractive scintillation support which permits the separation, pre-concentration and measurement of the radionuclides without additional steps of elution and sample preparation. However, only a few manufacturers provide PSm, and the low number of regular suppliers reduces its availability and restricts the compositions and sizes available. In this article, a synthesis method based on the extraction/evaporation methodology has been developed and successfully used for the synthesis of plastic scintillation microspheres. Seven different compositions of plastic scintillation microspheres have been synthesised; PSm1 with polystyrene, PSm2 with 2,5-Diphenyloxazol(PPO), PSm3 with p-terphenyl (pT), PSm4 with PPO and 1,4-bis(5-phenyloxazol-2-yl) (POPOP), PSm5 pT and (1,4-bis [2-methylstyryl] benzene) (Bis-MSB), PSm6 with PPO, POPOP and naphthalene and PSm7 with pT, Bis-MSB and naphthalene. The synthesised plastic scintillation microspheres have been characterised in terms of their morphology, detection capabilities and alpha/beta separation capacity. The microspheres had a median diameter of approximately 130 ?m. Maximum detection efficiency values were obtained for the PSm4 composition as follows 1.18% for 3H, 51.2% for 14C, 180.6% for 90Sr/90Y and 76.7% for 241Am. Values of the SQP(E) parameter were approximately 790 for PSm4 and PSm5. These values show that the synthesised PSm exhibit good scintillation properties and that the spectra are at channel numbers higher than in commercial PSm. Finally, the addition of naphthalene modifies the shape of the pulses produced by alpha and beta particles leading to better alpha/beta separation.

Santiago, L. M.; Bagán, H.; Tarancón, A.; Garcia, J. F.

2013-01-01

191

Spatial resolution in X-ray imaging with scintillating glass optical fiber plates  

Microsoft Academic Search

Some scintillating optical fiber plates, fabricated with terbium glasses are tested for their intrinsic spatial resolution under X-ray irradiation and the result is compared with a typical phosphor screen. The spatial resolution (CTF and MTF) is measured as a function of spatial frequency and the standard deviation of the corresponding Gaussian PSF is derived.

P. Pavan; G. Zanella; R. Zannoni; A. Marigo

1993-01-01

192

Boron Doped Plastic Scintillator Efficiency  

NASA Astrophysics Data System (ADS)

This talk will describe the progress made in an interdisciplinary development project aimed at cost-effective, neutron sensitive, plastic scintillator. Colorado School of Mines researchers with backgrounds in Physics, Chemistry, and Chemical Engineering have worked on the incorporation of ^10B in plastics through extrusion. First results on transparent samples using fluorescent spectroscopy and beta excitation will be presented.

Mahl, Adam; Chouinard-Dussault, Pascale; Pecinovsky, Cory; Potter, Andrew; Remedes, Tyler; Dorgan, John; Greife, Uwe

2013-04-01

193

A Solid State Scintillation Detector  

Microsoft Academic Search

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

George E. Wilcox

1967-01-01

194

Time response of plastic scintillators  

Microsoft Academic Search

Time-response characteristics of eight commercial plastic scintillators ; have been studied. Samples were excited by 50 ps electron or bremsstrahlung ; pulses. Sampling techniques were used to record the signal from a fast vacuum ; photodiode. Effects of surface preparation on time response were studied. The ; observed fwhm (in ns) for the three fastest plastics was 1.5, 2.0, and

P. B. Lyons; J. Stevens

1974-01-01

195

Radiation damage of plastic scintillators  

Microsoft Academic Search

Degradation and annealing mechanisms in polystyrene were studied in order to account for the losses in transmittance and light yield observed in polystyrene-based plastic scintillators. Special emphasis was put on irradiations in oxygen and on the oxygen annealing process. These experiments indicated that: (a) irradiations in which oxygen was continuously available throughout the bulk of the polystyrene sample were the

A. D. Bross; A. Pla-Dalmau

1992-01-01

196

Cerium doped elpasolite halide scintillators.  

SciTech Connect

Low-cost, high-performance gamma-ray spectrometers are urgently needed for proliferation detection and homeland security. The cost and availability of large scintillators used in the spectrometer generally hinge on their mechanical property and crystal symmetry. Low symmetry, intrinsically brittle crystals, such as these emerging lanthanide halide scintillators, are particularly difficult to grow in large sizes due to the development of large anisotropic thermomechanical stresses during solidification process. Isotropic cubic scintillators, such as alkali halides, while affordable and can be produced in large sizes, are poor spectrometers due to severe nonproportional response and modest light yield. This work investigates and compares four new elpasolite based lanthanide halides, including Cs2LiLaBr6, Cs2NaLaBr6, Cs2LiLaI6, and Cs2NaLaI6, in terms of their crystal symmetry, characteristics of photoluminescence and optical quantum efficiency. The mechanical property and thermal expansion behavior of the cubic Cs2LiLaBr6 will be reported. The isotropic nature of this material has potential for scaled-up crystal growth, as well as the possibility of low-cost polycrystalline ceramic processing. In addition, the proportional response with gamma-ray energy of directionally solidified Cs2LiLaBr6 will be compared with workhorse alkali halide scintillators. The processing challenges associated with hot forged polycrystalline elpasolite based lanthanide halides will also be discussed.

Doty, F. Patrick (Sandia National Laboratories, Livermore, CA); Shah, Kanai Subodhbhai (Radiation Monitoring Devices, Watertown, MA); Noda, Frank T.; Yang, Pin; Zhou, Xiao Wang (Sandia National Laboratories, Livermore, CA)

2010-05-01

197

VHF radio scintillations at Bombay  

NASA Astrophysics Data System (ADS)

The simultaneous recordings of the amplitude scintillations of VHF radio signals from nearby geostationary satellites Fleetsat (at 73 deg E long.) and Sirio (at 65 deg E) received at Bombay (geog. lat. 19 deg N, geog. long. 73 deg E, mag. lat. 15 deg N) have revealed systematic time shifts in the starting and the ending of the individual scintillation events. The ionosphere crossover points of the two transmission paths were separated by only 80 km in the east-west direction, which was smaller than the average size of the irregularity patches. Scintillations normally started after 1930 h, reached a maximum at 2200 h, and slowly decreased until 1000 h, after which no scintillations were observed. The speed of the irregularity patches computed from the time shifts of these events was about 150 m/s in the early hours of the night, decreasing to about 100 m/s by midnight and showing much lower velocities in the post-midnight hours.

Koparkar, P. V.; Rastogi, R. G.

1985-10-01

198

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

199

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

200

Extruded plastic scintillator for MINERvA  

SciTech Connect

An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. A new experiment at Fermilab is pursuing the use of extruded plastic scintillator. A new plastic scintillator strip is being tested and its properties characterized. The initial results are presented here.

Pla-Dalmau, Anna; Bross, Alan D.; /Fermilab; Rykalin, Victor V.; Wood, Brian M.; /NICADD, DeKalb

2005-11-01

201

Field Guides  

NSDL National Science Digital Library

This reference includes individual titles of note along with the most popular field guide series. For each guide, the author, publisher, and publication date are given. The diverse list has 17 individual titles, which cover everything from wildflowers in the Colorado mountains and insects north of Mexico to the natural history of vacant lots. There are detailed descriptions of four of the most popular field guide series: Audubon Society Guides, Golden Guides, Peterson Guides, and Stokes Nature Guide Series.

202

High Efficiency, Low Cost Scintillators for PET  

SciTech Connect

Inorganic scintillation detectors coupled to PMTs are an important element of medical imaging applications such as positron emission tomography (PET). Performance as well as cost of these systems is limited by the properties of the scintillation detectors available at present. The Phase I project was aimed at demonstrating the feasibility of producing high performance scintillators using a low cost fabrication approach. Samples of these scintillators were produced and their performance was evaluated. Overall, the Phase I effort was very successful. The Phase II project will be aimed at advancing the new scintillation technology for PET. Large samples of the new scintillators will be produced and their performance will be evaluated. PET modules based on the new scintillators will also be built and characterized.

Kanai Shah

2007-03-06

203

Optical properties of halide and oxide scintillators  

SciTech Connect

Knowledge of optical properties of scintillators is important both for the optimization of scintillator systems and the development of new materials particularly ceramic scintillators. Recent theoretical developments, especially new density functionals that enable accurate prediction of band gaps, have made it possible to perform quantitative calculations of the optical properties of scintillator materials. We used these techniques to obtain optical properties of a large number of high light output halide scintillators. These calculations showed that many halide scintillators have remarkably little optical anisotropy and may be good candidates for development as ceramic scintillators. These include materials such as CaI{sub 2}:Eu{sup 2+} that have very high light output and other favorable properties but are difficult to develop due to crystal growth issues. We review some of our recent results and present new results for CeCl{sub 3}.

Singh, David J [ORNL

2011-01-01

204

Newborn Screening  

MedlinePLUS

... When and How Babies are Screened Ten Significant Public Health Achievements ? United States, 2001-2010: Newborn Screening Improvements ... for any medical condition as soon as possible. Public Health Stories Meet the people behind newborn screening at ...

205

Effect of beam wander on the scintillation characterization for multiple beams  

NASA Astrophysics Data System (ADS)

An 4km optical link was established to examine the effect of beam wander on the scintillation characterization for multiple focus beams. Multiple beams that sample different portions of the atmosphere reduce the scintillation if the atmospheric turbulence each beam traverses is independent. How much the beam wander affects scintillation is determined by the number of the beams and the size of the beam wander variance. The number of mutually incoherent beams was 1, 3 or 6. Individual laser was launched from a separate region of the transmitter and focused on the flat screen with the horizontal distance of 4km by 350mm telescope. We recorded the illuminated flat screen with a CCD camera operating at 1kHz. We calculated the scintillation index of the illuminated area with the size of 8x8cm on the condition of untracked and tracked beams. A tracked beam generally refers to the situation in which the beam is tilt-corrected. However, There was no tilt-corrected in the experiment. Instead, the rms beam centroid of the area was aligned with the optical axis at each frame. Experimental results show that the scintillation index in tracked beam was larger than in the untracked beam case when the size of the Rytov variance ?2R is the same for one beam case, but for three and six beams, the scintillation values are almost. It is the reason that the root mean square variance of wander angle decreases as the number of beams increases. So the effect of beam wander is not evident for three and six beams. And increasing the number of beams on the condition of untracked and tracked cases does reduce the scintillation index as predicted.

Wu, Wu-ming; Sun, Quan; Ren, Guang-sen; Ning, Yu; Du, Rui; Wu, Yi

2013-08-01

206

Solid scintillators for receptor assays: an environmentally safe alternative to liquid scintillation cocktails.  

PubMed

Scintillation counting of tritiated ligands is widespread in receptor assays and has necessitated the use of scintillation cocktails containing environmentally damaging solvents that pose health hazards to their users. A safer mode of dry scintillation counting, based on the solid scintillator Xtalscint, was evaluated in whole-cell and membrane receptor assays. The results compared favorably with those obtained with glass-fiber filters and conventional liquid counting methods. It is concluded that solid scintillators may be used as an environmentally safer alternative to liquid scintillation in these assays. PMID:1653356

Hawkins, E F

1991-01-01

207

Ionospheric scintillation by a random phase screen: Spectral approach  

Microsoft Academic Search

relation function, is extended to a spectral description specified as a continuous function of spatial wavenumber with an intrinsic outer scale as would be expected from a turbulent medium. Two spectral forms were selected for comparison: (1) a power-law variation in wavenumber with a constant three-dimensional equal to 4, and (2) gaussian spectral variation. The results are applied to the

Clifford L. Rufenach

1975-01-01

208

Studies of long scintillation counters  

NASA Astrophysics Data System (ADS)

Current research in elementary particle physics requires particle detectors operating at the highest possible energy such as DO at the Tevatron at Fermilab, Atlas at the Large Hadron Collider (LHC), and the International Large Detector at the proposed International Large Collider (ILC). Research and development is ongoing for the detector technologies to use at the ILC. One of these efforts is the study of scintillation counters using silicon photomultiplier (SiPM) photodetectors for muon experiments. In particular, multipixelated photon detectors (MPPCs) are being developed as an attractive choice for photodetection. In connection with this, a test beam study (T995) occurred at the Meson Test Beam Facility (MTBF) at Fermilab in 2010. My thesis concerns that work, specifically calibration of the silicon photomultipliers that are attached at the end of fiber-optic wires embedded in scintillation material used in the T995 test beam study.

Shea, Robert J.

209

Silicon photomultipliers for scintillating trackers  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

210

Preparation and properties of scintillating glass doped with organic activators  

Microsoft Academic Search

A series of scintillating glasses were developed by doping organic activators into low melting temperature glasses according to different ratios. The fluorescence spectra and the transmission spectra of some scintillating glasses were explored and the actual concentration organic in scintillating glass was estimated. The results show that it is feasible to prepare the scintillating glass by doing organic scintillating activators

Dong-mei ZHU; Fa LUO; Hong-sheng ZHAO; Wan-cheng ZHOU

2006-01-01

211

Scintillation mechanisms in cerium fluoride  

Microsoft Academic Search

Ultraviolet photoelectron spectroscopy, optical transmission, fluorescence excitation spectroscopy, and time-resolved fluorescence spectroscopy are used to investigate the scintillation mechanisms of cerium fluoride (CeF 3) and of lanthanum fluoride doped with cerium in concentration s between 0.01% and 50% mole fraction cerium. In LaF 3:Ce the absorption of either optical or ionizing radiation directly or indirectly results in excitation of the

W. W. Moses; S. E. Derenzo; M. J. Weber; A. K. Ray-Chaudhuri; F. Cerrina

1994-01-01

212

Scintillation properties of lead sulfate  

SciTech Connect

In this paper the authors report on the scintillation properties of lead sulfate (PbSO[sub 4]), a scintillator that shows promise as a high energy photon detector. Its physical properties are well suited for gamma detection, as it has a density of 6.4 gm/cm[sup 3], a 1/e attenuation length for 511 keV photons of 1.2 cm, is not affected by air or moisture, and is cut and polished easily. In 99.998% pure PbSO[sub 4] crystals at room temperature excited by 511 keV annihilation photons, the fluorescence decay lifetime contains significant fast components having 1.8 ns (5%) and 19 ns (36%) decay times, but with longer components having 95 ns (36%) and 425 ns (23%) decay times. The peak emission wavelength is 335 nm, which is transmitted by borosilicate glass windowed photomultiplier tubes. The total scintillation light output increases with decreasing temperature from 3,200 photons/MeV at +45[degrees] C to 4,900 photons/MeV at room temperature (+25[degrees] C) and 68,500 photons/MeV at [minus] 145[degrees] C.

Moses, W.W.; Derenzo, S.E. (Lawrence Berkeley Lab., CA (United States)); Schlichta, P.J. (Crystal Research, San Pedro, CA (United States))

1992-10-01

213

Behaviour of HILAT scintillation over Spitsbergen  

NASA Astrophysics Data System (ADS)

Results of the amplitude scintillation morphology of the HILAT satellite 137 MHz beacon transmission as measured at the Polish Polar Station at Hornsund, Spitsbergen (Lambda = 73.4 deg) are presented. Seasonal, diurnal and latitudinal dependencies of scintillation intensity on magnetic activity were analyzed from over 2250 satellite passes recorded at solar minimum between April 1985 and March 1986. Regions with strong scintillation intensity appear to follow the auroral oval expansion and to move sunward with increasing level of magnetic activity. Maximum amplitude scintillation region coincides with the dayside cusp/cleft position during high magnetic activity. The dawn-dusk asymmetry in scintillation intensity is more distinct in winter than other months. The estimated summer/winter ratio of scintillation intensity is 1.4:1. Numerical simulations compared with the observational results indicate that high latitude irregularities under 1 km are field-aligned and rodlike rather than sheetlike.

Gola, M.; Wernik, A. W.; Franke, S. J.; Liu, C. H.; Yeh, K. C.

1992-09-01

214

Coorelation between VHF scintillation and spread F  

NASA Astrophysics Data System (ADS)

The VHF scintillation observed over Bhopal, a station near the northern crest of the equatorial anomaly region, using the 244 MHz radio signal from FLEETSAT (730). The data use to study the occurrence characteristics of scintillation are recorded from March to April 2001 and then September to October 2001. The occurrences of scintillation are compared with the occurrence of spread-F over Delhi as observed by the modern digital ionosonde. The scintillation events are closely associated with the range type spread-F. In this paper the parameters of geomagnetic activity like Kp and Ap are used to study the association of the amplitude scintillation and spread-F. It is observed that an increase in magnetic activity suppressed the occurrence of scintillation and spread-F.

Smita, S.; Rashmi, R.; Gwal, G.

2003-04-01

215

Evaluation of different scintillators for 1MV NDE x-ray imaging  

NASA Astrophysics Data System (ADS)

X-ray radiography is an important and frequently used NDE method of testing metal structures, such as tube welding quality, cracks and voids in cast iron or other metals. It gives fast and visible answer for structural defects. The Varian high energy portal imagers on Clinacs used in cancer treatment were tested for this purpose. We compared the traditional Gadox (LANEX) screen with and without a 1mm Cu buildup plate as used clinically. We also tested different hybrid scintillators, which consisted of different phosphor layers deposited onto fiberoptic plates. The last screen tested was a 2cm thick fiberoptic plate which contained scintillating fibers. The sensitivity (ADU = number of digital counts per a given X-ray dose), the resolution (MTF - modulation transfer function) and the DQE (detective quantum efficiency) were compared, with a 1 MV source, for these X-ray conversion screens. We found that the additional 1mm Cu plate, which improves the absorption and the contrast at 6 or higher energy MeV imaging, does not improve the image quality at 1MV. Rather it attenuates the X-rays, resulting in lower sensitivity and a lower DQE(0) of 2.2% with the additional Cu plate compared to DQE(0) of ~4% without the Cu plate. The hybrid scintillators with evaporated phosphors on fiberoptic plates tested were too thin resulting in low sensitivity. The best results were obtained from the thick scintillating fiberoptic screens, which provided the best DQE and high resolution with the 1MV X-ray beam. Further optimization is planned by changing the thickness of the scintillating fiber optic plate.

Zentai, George; Ganguly, Arundhuti; Visrshup, Gary

2014-03-01

216

Screening for Drug-Induced Hepatotoxicity in Primary Mouse Hepatocytes Using Acetaminophen, Amiodarone, and Cyclosporin A as Model Compounds: An Omics-Guided Approach  

PubMed Central

Abstract Drug-induced hepatotoxicity is a leading cause of attrition for candidate pharmaceuticals in development. New preclinical screening methods are crucial to predict drug toxicity prior to human studies. Of all in vitro hepatotoxicity models, primary human hepatocytes are considered as ‘the gold standard.’ However, their use is hindered by limited availability and inter-individual variation. These barriers may be overcome by using primary mouse hepatocytes. We used differential in gel electrophoresis (DIGE) to study large-scale protein expression of primary mouse hepatocytes. These hepatocytes were exposed to three well-defined hepatotoxicants: acetaminophen, amiodarone, and cyclosporin A. Each hepatotoxicant induces a different hepatotoxic phenotype. Based on the DIGE results, the mRNA expression levels of deregulated proteins from cyclosporin A-treated cells were also analyzed. We were able to distinguish cyclosporin A from controls, as well as acetaminophen and amiodarone-treated samples. Cyclosporin A induced endoplasmic reticulum (ER) stress and altered the ER-Golgi transport. Moreover, liver carboxylesterase and bile salt sulfotransferase were differentially expressed. These proteins were associated with a protective adaptive response against cyclosporin A-induced cholestasis. The results of this study are comparable with effects in HepG2 cells. Therefore, we suggest both models can be used to analyze the cholestatic properties of cyclosporin A. Furthermore, this study showed a conserved response between primary mouse hepatocytes and HepG2 cells. These findings collectively lend support for use of omics strategies in preclinical toxicology, and might inform future efforts to better link preclinical and clinical research in rational drug development.

Van Summeren, Anke; Renes, Johan; Lizarraga, Daneida; Bouwman, Freek G.; Noben, Jean-Paul; van Delft, Joost H. M.; Kleinjans, Jos C. S.

2013-01-01

217

A compact, in vivo screen of all 6-mers reveals drivers of tissue-specific expression and guides synthetic regulatory element design  

PubMed Central

Background Large-scale annotation efforts have improved our ability to coarsely predict regulatory elements throughout vertebrate genomes. However, it is unclear how complex spatiotemporal patterns of gene expression driven by these elements emerge from the activity of short, transcription factor binding sequences. Results We describe a comprehensive promoter extension assay in which the regulatory potential of all 6 base-pair (bp) sequences was tested in the context of a minimal promoter. To enable this large-scale screen, we developed algorithms that use a reverse-complement aware decomposition of the de Bruijn graph to design a library of DNA oligomers incorporating every 6-bp sequence exactly once. Our library multiplexes all 4,096 unique 6-mers into 184 double-stranded 15-bp oligomers, which is sufficiently compact for in vivo testing. We injected each multiplexed construct into zebrafish embryos and scored GFP expression in 15 tissues at two developmental time points. Twenty-seven constructs produced consistent expression patterns, with the majority doing so in only one tissue. Functional sequences are enriched near biologically relevant genes, match motifs for developmental transcription factors, and are required for enhancer activity. By concatenating tissue-specific functional sequences, we generated completely synthetic enhancers for the notochord, epidermis, spinal cord, forebrain and otic lateral line, and show that short regulatory sequences do not always function modularly. Conclusions This work introduces a unique in vivo catalog of short, functional regulatory sequences and demonstrates several important principles of regulatory element organization. Furthermore, we provide resources for designing compact, reverse-complement aware k-mer libraries.

2013-01-01

218

Clinical Neuropathology practice guide 6-2013: morphology and an appropriate immunohistochemical screening panel aid in the identification of synovial sarcoma by neuropathologists  

PubMed Central

Aims: Pathologists are under increasing pressure to accurately subclassify sarcomas, yet neuropathologists have limited collective experience with rare sarcoma types such as synovial sarcoma. We reviewed 9 synovial sarcomas affecting peripheral nerve diagnosed by neuropathologists and explored the morphologic and immunohistochemical differences between these and MPNST. Our goal was to make practical recommendations for neuropathologists regarding which spindle cell tumors affecting nerve should be sent for SYT-SSX testing. Methods: Clinical records and genetics were reviewed retrospectively and central pathology review of 9 synovial sarcomas and 6 MPNST included immunohistochemistry for SOX10, S100, BAF47, CK (lmw, pan, CK7, CK19), EMA, CD34, bcl2, CD99, and neurofilament. Results: Common synovial sarcoma sites were brachial plexus, spinal and femoral nerve, none were “intra-neural”, all had the SYT-SSX1 translocation, and 6/9 were monophasic with myxoid stroma and distinct collagen. Half of the monophasic synovial sarcomas expressed CK7, CK19 or panCK in a “rare positive cells pattern”, 8/9 (89%) expressed EMA, and all were SOX10 immunonegative with reduced but variable BAF47 expression. Conclusions: We recommend that upon encountering a cellular spindle cell tumor affecting nerve neuropathologists consider the following: 1) SYT-SSX testing should be performed on any case with morphology suspicious for monophasic synovial sarcoma including wiry or thick bands of collagen and relatively monomorphous nuclei; 2) neuropathologists should employ a screening immunohistochemical panel including one of CK7, panCK or CK19, plus EMA, S100 and SOX10, and 3) SYT-SSX testing should be performed on any spindle cell tumor with CK and/or EMA immunopositivity if SOX10 immunostaining is negative or only labels entrapped nerve elements.

Keith, Julia Lee; Bilbao, Juan; Croul, Sidney; Ang, Lee Cyn; Guiot, Marie-Christine; Rossiter, John; Ghorab, Zeina; Hawkins, Cynthia; Karamchandani, Jason

2013-01-01

219

Scintillation materials for neutron imaging detectors  

Microsoft Academic Search

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

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

2004-01-01

220

Neutron position-sensitive scintillation detector  

DOEpatents

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

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

1984-01-01

221

Physical characteristics of polymethylmethacrylate scintillator SOFG-120  

NASA Astrophysics Data System (ADS)

Characteristics of the polimethylmetacrylate scintillator which is used for the fast scintillating trigger in the liquid argon neutrino detector of the Tagged Neutrino Facility are studied. Scintillator SOFG-120 consists of PMMA-85%, naphtalene-14%, PPO-0.8%, and POPOP-0.08%. As main characteristics, spectral emission, light output (50% NE-110), time resolution 4.8 ns, and attenuation length (for sheet 1265x333x22 mm(exp 3)) lambda approximately = m were obtained.

Belikov, S. V.; Gurzhiev, S. N.; Dyachkov, A. P.

222

Spacecraft Radio Scintillation and Solar System Exploration  

NASA Technical Reports Server (NTRS)

When a wave propagates through a turbulent medium, scattering by the random refractive index inhomogeneities can lead to a wide variety of phenomena that have been the subject of extensive study. The observed scattering effects include amplitude or intensity scintillation, phase scintillation, angular broadening, and spectral broadening, among others. In this paper, I will refer to these scattering effects collectively as scintillation. Although the most familiar example is probably the twinkling of stars (light wave intensity scintillation by turbulence in the Earth's atmosphere), scintillation has been encountered and investigated in such diverse fields as ionospheric physics, oceanography, radio astronomy, and radio and optical communications. Ever since planetary spacecraft began exploring the solar system, scintillation has appeared during the propagation of spacecraft radio signals through planetary atmospheres, planetary ionospheres, and the solar wind. Early studies of these phenomena were motivated by the potential adverse effects on communications and navigation, and on experiments that use the radio link to conduct scientific investigations. Examples of the latter are radio occultation measurements (described below) of planetary atmospheres to deduce temperature profiles, and the search for gravitational waves. However,these concerns soon gave way to the emergence of spacecraft radio scintillation as a new scientific tool for exploring small-scale dynamics in planetary atmospheres and structure in the solar wind, complementing in situ and other remote sensing spacecraft measurements, as well as scintillation measurements using natural (celestial) radio sources. The purpose of this paper is to briefly describe and review the solar system spacecraft radio scintillation observations, to summarize the salient features of wave propagation analyses employed in interpreting them, to underscore the unique remote sensing capabilities and scientific relevance of the scintillation measurements, and to highlight some of the scientific results obtained to date. Special emphasis is placed on comparing the remote sensing features of planetary and terrestrial scintillation measurements, and on contrasting spacecraft and natural radio source scintillation measurements. I will first discuss planetary atmospheres and ionospheres, and then the solar wind.

Woo, Richard

1993-01-01

223

Designing an optimally proportional inorganic scintillator  

NASA Astrophysics Data System (ADS)

The nonproportionality observed in the light yield of inorganic scintillators is studied theoretically as a function of the rates of bimolecular and Auger quenching processes occurring within the electron track initiated by a gamma- or X-ray photon incident on a scintillator. Assuming a cylindrical track, the influence of the track radius and concentration of excitations created within the track on the scintillator light yield is also studied. Analysing the calculated light yield a guideline for inventing an optimally proportional scintillator with optimal energy resolution is presented.

Singh, Jai; Koblov, Alexander

2012-09-01

224

Scintillating optical fibers in astrophysics research  

NASA Astrophysics Data System (ADS)

This work reports on the use of scintillating optical fibers in two experiments being prepared for space flight. The Advanced Composition Explorer (ACE) [1], to be launched in August 1997, includes the Cosmic Ray Isotope Spectrometer (CRIS) which uses a Scintillating Optical Fiber Trajectory detector (SOFT) for trajectory information. The Scintillating Fiber Telescope for Energetic Radiation (SIFTER) is currently being developed as a high energy gamma ray telescope for a future space mission. It uses scintillating optical fibers distributed throughout the converter material to allow detailed study of the development of the electromagnetic cascade produced by gamma rays.

Klarmann, J.; Binns, W. R.; Hink, P. L.; Israel, M. H.; Fishman, G. J.; Parnell, T. A.; Pendleton, G. N.

1997-02-01

225

Divalent fluoride doped cerium fluoride scintillator  

DOEpatents

The use of divalent fluoride dopants in scintillator materials comprising cerium fluoride is disclosed. The preferred divalent fluoride dopants are calcium fluoride, strontium fluoride, and barium fluoride. The preferred amount of divalent fluoride dopant is less than about two percent by weight of the total scintillator. Cerium fluoride scintillator crystals grown with the addition of a divalent fluoride have exhibited better transmissions and higher light outputs than crystals grown without the addition of such dopants. These scintillators are useful in radiation detection and monitoring applications, and are particularly well suited for high-rate applications such as positron emission tomography (PET).

Anderson, David F. (630 Sylvan Pl., Batavia, IL 60510); Sparrow, Robert W. (28 Woodlawn Dr., Sturbridge, MA 01566)

1991-01-01

226

Waveshifters and Scintillators for Ionizing Radiation Detection  

SciTech Connect

Scintillation and waveshifter materials have been developed for the detection of ionizing radiation in an STTR program between Ludlum Measurements, Inc. and the University of Notre Dame. Several new waveshifter materials have been developed which are comparable in efficiency and faster in fluorescence decay than the standard material Y11 (K27) used in particle physics for several decades. Additionally, new scintillation materials useful for fiber tracking have been developed which have been compared to 3HF. Lastly, work was done on developing liquid scintillators and paint-on scintillators and waveshifters for high radiation environments.

B.Baumgaugh; J.Bishop; D.Karmgard; J.Marchant; M.McKenna; R.Ruchti; M.Vigneault; L.Hernandez; C.Hurlbut

2007-12-11

227

Divalent fluoride doped cerium fluoride scintillator  

SciTech Connect

The use of divalent fluoride dopants in scintillator materials comprising cerium fluoride is disclosed. The preferred divalent fluoride dopants are calcium fluoride, strontium fluoride, and barium fluoride. The preferred amount of divalent fluoride dopant is less than about two percent by weight of the total scintillator. Cerium fluoride scintillator crystals grown with the addition of a divalent fluoride have exhibited better transmissions and higher light outputs than crystals grown without the addition of such dopants. These scintillators are useful in radiation detection and monitoring applications, and are particularly well suited for high-rate applications such as positron emission tomography.

Anderson, D.F.; Sparrow, R.W.

1992-01-01

228

Towards two-dimensional brachytherapy dosimetry using plastic scintillator: localization of the scintillation process  

Microsoft Academic Search

Detecting the scintillation light coming from a thin sheet of plastic scintillator (PS) provides a promising fast and precise tissue equivalent method for radiation dose measurements in two dimensions. The successful implementation of such technique requires high efficiency, dosimetric tissue equivalence and high localization of the scintillation process. The last is needed to assure that the light photons originating from

A. S Kirov; W. R Binns; J. F Dempsey; J. W Epstein; P. F Dowkontt; S Shrinivas; C Hurlbut; J. F Williamson

2000-01-01

229

Optimizing light collection from thin scintillators used in a beta-ray camera for surgical use  

SciTech Connect

The authors are developing a 1--2 cm{sup 2} area camera for imaging the distribution of beta-emitting radiopharmaceuticals at the surface of tissue exposed during surgery. The front end consists of a very thin continuous or segmented scintillator sensitive to betas (positrons or electrons) of a few hundred keV, yet insensitive to gamma rays. The light from the scintillator is piped through clear fibers to the photon detector (PD). This approach requires that a sufficient number of scintillation photons be transported from the scintillator, through the fibers to the PD. The scintillator, reflector, surface treatments, geometry, fiber light guides, and optical couplings must be optimized. The authors report here on efforts made to optimize the light collection from <3 mm thick plastic and CaF{sub 2}(Eu) disk coupled to a 5 cm long bundle of clear optical fibers, on average, {approximately}250 photoelectrons are produced at a PMT photocathode for a {sup 204}Tl beta flood source (E{sub max} = 763 keV). This corresponds to a sufficient number of photoelectrons for <1 mm resolution imaging capabilities for the proposed camera.

Levin, C.S.; MacDonald, L.R.; Tornai, M.P.; Hoffman, E.J.; Park, J. [Univ. of California, Los Angeles, CA (United States)] [Univ. of California, Los Angeles, CA (United States)

1996-06-01

230

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

SciTech Connect

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

Sawant, Amit; Antonuk, Larry E.; El-Mohri, Youcef; Zhao Qihua; Li Yixin; Su Zhong; Wang Yi; Yamamoto, Jin; Du Hong; Cunningham, Ian; Klugerman, Misha; Shah, Kanai [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48105 (United States); Imaging Research Laboratories, Robarts Research Institute, London, Ontario N6A 5C1 (Canada); Radiation Monitoring Devices, Watertown, Massachusetts 02472 (United States)

2005-10-15

231

Scintillation properties of lead sulfate  

SciTech Connect

We report on the scintillation properties of lead sulfate (PbSO{sub 4}), a scintillator that show promise as a high energy photon detector. It physical properties are well suited for gamma detection, as its has a density of 6.4 gm/cm{sup 3}, a 1/e attenuation length for 511 keV photons of 1.2 cm, is not affected by air or moisture, and is cut and polished easily. In 99.998% pure PbSO{sub 4} crystals at room temperature excited by 511 keV annihilation photons, the fluorescence decay lifetime contains significant fast components having 1.8 ns (5%) and 19 ns (36%) decay times, but with longer components having 95 ns (36%) and 425 ns (23%) decays times. The peak emission wavelength is 335 nm, which is transmitted by borosilicate glass windowed photomultiplier tubes. The total scintillation light output increases with decreasing temperature fro 3,200 photons/MeV at +45{degrees}C to 4, 900 photons/MeV at room temperature (+25{degrees}C) and 68,500 photons/MeV at {minus}145{degrees}C. In an imperfect, 3 mm cube of a naturally occurring mineral form of PbSO{sub 4} (anglesite) at room temperature, a 511 keV photopeak is seen with a total light output of 60% that BGO. There are significant sample to sample variations of the light output among anglesite samples, so the light output of lead sulfate may improve when large synthetic crystals become available. 10 refs.

Moses, W.W.; Derenzo, S.E. (Lawrence Berkeley Lab., CA (United States)); Shlichta, P.J. (Crystal Research, San Pedro, CA (United States))

1991-11-01

232

Liquid-krypton scintillation calorimeter  

SciTech Connect

An electromagnetic scintillation calorimeter using liquid krypton or xenon as the working medium has been built. The calorimeter consists of 45 tapered light-collecting cells with dimensions of (2.1 X 2.1) X 40 X (4.15 X 4.15) cm made from aluminum-coated mylar film 50 {mu}m thick. The light from each cell is detected by photomultipliers. The calorimeter filled with liquid krypton was exposed to a beam of secondary particles with a momentum of 400 MeV/c from the ITEP accelerator. The results of the first test are given.

Akimov, D.Yu.; Afonas`ev, V.N.; Bolozdynya, A.I. [Institute of Experimental and Theoretical Physics, Moscow (Russian Federation)

1995-01-01

233

Photodetectors for Scintillator Proportionality Measurement  

SciTech Connect

We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high ({approx}50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.

Moses, William W.; Choong, Woon-Seng; Hull, Giulia; Payne, Steve; Cherepy, Nerine; Valentine, J.D.

2010-10-18

234

Single-Crystal Scintillation Materials  

Microsoft Academic Search

\\u000a \\u000a Scintillation materials are \\u000a \\u000a employed to detect x-ray and ?-ray photons or accelerated particles. Wide-bandgap semiconductor or insulator materials with a high degree of structural\\u000a perfection are suitable for this purpose. They must accomplish fast and efficient transformation of incoming high-energy photon\\/particles\\u000a to a number of electron–hole pairs collected in the conduction and valence bands, respectively, and their radiative recombination\\u000a at suitable luminescence

Martin Nikl; Anna Vedda; Valentin V. Laguta

2010-01-01

235

Scintillation modeling using in situ data  

Microsoft Academic Search

Satellite in situ measurements of plasma (electron) density fluctuations provide direct information about the structure and morphology of irregularities that are responsible for scintillation of radio waves on transionospheric links. When supplemented with the ionosphere model and irregularity anisotropy model, they can be applied to model morphology of scintillation provided a suitable propagation model is used. In this paper we

A. W. Wernik; L. Alfonsi; M. Materassi

2007-01-01

236

Binderless composite scintillator for neutron detection  

DOEpatents

Composite scintillator material consisting of a binderless sintered mixture of a Lithium (Li) compound containing .sup.6Li as the neutron converter and Y.sub.2SiO.sub.5:Ce as the scintillation phosphor, and the use of this material as a method for neutron detection. Other embodiments of the invention include various other Li compounds.

Hodges, Jason P [Knoxville, TN; Crow, Jr; Lowell, M [Oak Ridge, TN; Cooper, Ronald G [Oak Ridge, TN

2009-03-10

237

A new radiation stable plastic scintillator  

Microsoft Academic Search

The influence of various components of a plastic scintillator (high concentrations of primary dopant, secondary fluor, diffusion enhancer and stabilizer) on its radiation hardness has been experimentally determined. The diffusion enhancing technique was shown to be the most powerful tool for improving radiation hardness. A new polystyrene scintillator that decreases its light output by only 4% after 2.8 Mrad irradiation

V. G. Senchishin; F. Markley; V. N. Lebedev; V. E. Kovtun; V. S. Koba; A. V. Kuznichenko; V. D. Tizkaja; J. A. Budagov; G. Bellettini; V. P. Seminozhenko; I. I. Zalubovsky; I. E. Chirikov-Zorin

1995-01-01

238

Internet access to data for scintillation compounds.  

National Technical Information Service (NTIS)

The LBL Pulsed X-Ray Facility has scintillation data on a large variety of inorganic scintillators. We offer this information on all compounds that we have tested. The only restrictions/favors that we ask users of this data are: (1) The data is intended f...

W. W. Moses A. C. West S. E. Derenzo

1995-01-01

239

Epoxy resins produce improved plastic scintillators  

NASA Technical Reports Server (NTRS)

Plastic scintillator produced by the substitution of epoxy resins for the commonly used polystyrene is easy to cast, stable at room temperature, and has the desirable properties of a thermoset or cross-linked system. Such scintillators can be immersed directly in strong solvents, an advantage in many chemical and biological experiments.

Markley, F. W.

1967-01-01

240

Scintillator handbook with emphasis on cesium iodide  

NASA Technical Reports Server (NTRS)

This report provides a background of reasonable depth and reference material on scintillators in general. Particular attention is paid to the cesium iodide scintillators as used in the High Energy Astronomy Observatory (HEAO) experiments. It is intended especially for use by persons such as laboratory test personnel who need to obtain a working knowledge of these materials and their characteristics in a short time.

Tidd, J. L.; Dabbs, J. R.; Levine, N.

1973-01-01

241

Luminescence and Scintillation Properties at the Nanoscale  

Microsoft Academic Search

This contribution is a review of the luminescence and scintillation properties of nanoparticles (NP), particularly doped insulators. Luminescence spectroscopy is an appropriate tool to probe matter at the nanoscale. Luminescence is also the last stage of the scintillation process. Specific surface and structural effects occurring in NP are reported. Their consequences on the NP luminescence properties are discussed. Parts of

Christophe Dujardin; David Amans; Andrei Belsky; Frederic Chaput; Gilles Ledoux; Anne Pillonnet

2010-01-01

242

Electromagnetic Calorimetry Using Scintillating Plastic Fibres.  

National Technical Information Service (NTIS)

When used in lead-scintillator sandwich calorimetry, scintillating optical fibers offer a new way to achieve fine grain sampling and hereby to improve the energy and spatial resolution of a technique still unbeaten for timing and compactness. A small calo...

H. Burmeister P. Sonderegger J. M. Gago A. Maio M. Pimenta

1983-01-01

243

Making the most of aging scintillator  

Microsoft Academic Search

Large-area scintillation counters used for triggering on muons at collider detectors can involve long transmission lengths which make the collection of an adequate amount of light difficult. This is a problem which aggravates as scintillator properties deteriorate with time and\\/or absorbed radiation. Inspired by the technique presently being applied to the construction of its new muon counters, a solution has

S. Cabrera; D. Cauz; D. Dreossi; K. Ebina; M. Iori; M. Incagli; G. Introzzi; A. Menzione; G. Pauletta; T. Ogawa; A. Penzo; L. Santi; G. Velev; I. Vila; K. Yorita

2000-01-01

244

Health Screening  

MedlinePLUS

Screenings are tests that look for diseases before you have symptoms. Screening tests can find diseases early, when they're easier ... pressure High cholesterol Osteoporosis Overweight and obesity Which tests you need depends on your age, your sex, ...

245

Application of small inexpensive side-on (side-window) photomultiplier tubes for scintillating fiber readout  

Microsoft Academic Search

Small inexpensive side-on photomultiplier tubes (PMTs) with excellent characteristics were tested for scintillating fiber readout. The location of the photocathode and nonuniform response of the photomultiplier pose problems in fiber or light-guide readout. To overcome these problems, a fiber-to-PMT coupling technique has been devised and tested which partially collimates the cone of light exiting a fiber by using small spherical

A. G. Weisenberger; B. Kross; S. Majewski; R. Wojcik; C. Zorn

1991-01-01

246

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

247

GPS phase scintillation caused by conjugate auroras  

NASA Astrophysics Data System (ADS)

Auroral ionospheric irregularities produced by energetic particle precipitation are known to cause scintillation of transionospheric radio signals. The data obtained by the GPS Ionospheric Scintillation and TEC Monitors (GISTMs) operated in the Arctic and Antarctica are used in an inter-hemispheric study of GPS phase scintillation. The Canadian High Arctic Ionospheric Network (CHAIN) includes two GPS receivers in Iqaluit and Qikiqtarjuaq that are approximately conjugate with South Pole station. An all-sky imager is presently located at South Pole and the Arctic sites are equipped with riometers sensitive to energetic particle precipitation causing ionospheric density enhancements. GPS phase scintillation events closely associated with auroral brightenings and substorms were observed during ionospheric disturbances caused by high-speed solar wind streams. Instances of simultaneity of scintillation and the associated auroral events at conjugate locations are reported.

Jayachandran, P. T.; Prikryl, P.; Mitchell, C. N.; Ebihara, Y.; Weatherwax, A. T.; Danskin, D. W.; Spogli, L.

2011-12-01

248

Scintillation materials for medical applications  

SciTech Connect

This report covers the first seven months of the first year of our work under the above Grant. As such, it is rather preliminary. We shall describe the concrete steps taken to implement the program. In Section 2 we shall describe the progress towards the development of the instrumentation and facilities needed to conduct the work and the materials which have been acquired. In Section 3 we shall give an account on preliminary measurements which have already been made as well as some calculations aimed at interpreting experimental results. Additionally we have undertaken to expand our general way of thinking about the problem of improving scintillator materials. This subject is covered in the Appendix Scintillator Research, which is an evolving document, not to be regarded as finished. In fact the last section cannot be finished in time for this Report. We believe it serves the dual purpose of articulating the research goals and priorities for our own purposes and at the same time to communicating them to our sponsor. 6 refs., 14 figs., 5 tabs.

Lempicki, A.; Wojtowicz, A.J.; Berman, E.

1991-01-01

249

Simulation of optical interstellar scintillation  

NASA Astrophysics Data System (ADS)

Aims: Stars twinkle because their light propagates through the atmosphere. The same phenomenon is expected on a longer time scale when the light of remote stars crosses an interstellar turbulent molecular cloud, but it has never been observed at optical wavelengths. The aim of the study described in this paper is to fully simulate the scintillation process, starting from the molecular cloud description as a fractal object, ending with the simulations of fluctuating stellar light curves. Methods: Fast Fourier transforms are first used to simulate fractal clouds. Then, the illumination pattern resulting from the crossing of background star light through these refractive clouds is calculated from a Fresnel integral that also uses fast Fourier transform techniques. Regularisation procedure and computing limitations are discussed, along with the effect of spatial and temporal coherency (source size and wavelength passband). Results: We quantify the expected modulation index of stellar light curves as a function of the turbulence strength - characterised by the diffraction radius Rdiff - and the projected source size, introduce the timing aspects, and establish connections between the light curve observables and the refractive cloud. We extend our discussion to clouds with different structure functions from Kolmogorov-type turbulence. Conclusions: Our study confirms that current telescopes of ~4 m with fast-readout, wide-field detectors have the capability of discovering the first interstellar optical scintillation effects. We also show that this effect should be unambiguously distinguished from any other type of variability through the observation of desynchronised light curves, simultaneously measured by two distant telescopes.

Habibi, F.; Moniez, M.; Ansari, R.; Rahvar, S.

2013-04-01

250

Atmospheric scintillations and laser safety  

NASA Astrophysics Data System (ADS)

Laser devices are currently in widespread use in particular by armed forces for different tasks. Electro-optical sensors as well as unprotected human eyes are extremely sensitive to laser radiation and can be permanently damaged from direct or reflected beams. Laser damage depends on the interaction between the laser beam and the atmosphere in which it traverses. The atmospheric conditions, including the range, terrain features, turbulence, and atmospheric particulates, may alter the laser's effect on different electro-optical devices and systems. When a laser beam passes through the atmosphere the optical turbulence affects the beam. As a result, temporal intensity fluctuations (scintillations) or spatial variations in intensity within a beam cross-section occur. Atmospheric scintillations pose a safety problem because an observer or sensor can be subjected to the risk of a localized irradiance (local focusing effect) much greater than that which would occur in a non-turbulent medium. In the present work, the influence of the atmospheric channel on laser safety is investigated by use of experimental data of laser beam propagation statistics for different atmospheric conditions. The results can be important in the area of laser remote sensing, wireless optical communications, and active imaging.

Zilberman, Arkadi; Golbraikh, Ephim; Kopeika, Norman S.

2011-09-01

251

Scintillation proximity assay using polymeric membranes  

SciTech Connect

Liquid scintillation counting (LSC) is typically used to quantify electron emitting isotopes. In LSC, radioactive samples are dissolved in an organic fluor solution (scintillation cocktail) to ensure that the label is close enough to the fluor molecules to be detected. Although efficient, scintillation cocktail is neither specific or selective for samples labeled with the same radioisotope. Scintillation cocktail is flammable posing significant health risks to the user and is expensive to purchase and discard. Scintillation Proximity Assay (SPA) is a radioanalytical technique where only those radiochemical entities (RCE's) bound to fluor containing matrices are detected. Only bound RCE's are in close enough proximity the entrapped fluor molecules to induce scintillations. Unbound radioligands are too far removed from the fluor molecules to be detected. The research in this dissertation focused on the development and evaluation of fluor-containing membranes (scintillation proximity membranes, SP membranes) to be used for specific radioanalytical techniques without using scintillation cocktail. Polysulfone and PVC SP membranes prepared in our laboratory were investigated for radioimmunossay (RIA) where only bound radioligand is detected, thereby eliminating the separation step impeding the automation of RIA. These SP membranes performed RIA where the results were nearly identical to commercial SP microbeads. SP membranes functionalized with quaternary ammonium hydroxide moieties were able to trap and quantify [sup 14]CO[sub 2] without using liquid scintillation cocktail. RCE's bound in the pore structure of SP membranes are intimate with the entrapped fluor providing the geometry needed for high detection efficiencies. Absorbent SP membranes were used in radiation surveys and were shown to be as effective as conventional survey techniques using filter paper and scintillation cocktail.

Mansfield, R.K.

1992-01-01

252

Scintillation Effects on Space Shuttle GPS Data  

NASA Technical Reports Server (NTRS)

Irregularities in ionospheric electron density result in variation in amplitude and phase of Global Positioning System (GPS) signals, or scintillation. GPS receivers tracking scintillated signals may lose carrier phase or frequency lock in the case of phase sc intillation. Amplitude scintillation can cause "enhancement" or "fading" of GPS signals and result in loss of lock. Scintillation can occur over the equatorial and polar regions and is a function of location, time of day, season, and solar and geomagnetic activity. Mid latitude regions are affected only very rarely, resulting from highly disturbed auroral events. In the spring of 1998, due to increasing concern about scintillation of GPS signals during the upcoming solar maximum, the Space Shuttle Program began to assess the impact of scintillation on Collins Miniaturized Airborne GPS Receiver (MAGR) units that are to replace Tactical Air Control and Navigation (TACAN) units on the Space Shuttle orbiters. The Shuttle Program must determine if scintillation effects pose a threat to safety of flight and mission success or require procedural and flight rule changes. Flight controllers in Mission Control must understand scintillation effects on GPS to properly diagnose "off nominal" GPS receiver performance. GPS data from recent Space Shuttle missions indicate that the signals tracked by the Shuttle MAGR manifest scintillation. Scintillation is observed as anomalous noise in velocity measurements lasting for up to 20 minutes on Shuttle orbit passes and are not accounted for in the error budget of the MAGR accuracy parameters. These events are typically coincident with latitude and local time occurrence of previously identified equatorial spread F within about 20 degrees of the magnetic equator. The geographic and seasonal history of these events from ground-based observations and a simple theoretical model, which have potential for predicting events for operational purposes, are reviewed.

Goodman, John L.; Kramer, Leonard

2001-01-01

253

A temporal method of avoiding the Cerenkov radiation generated in organic scintillator dosimeters by pulsed mega-voltage electron and photon beams.  

PubMed

The output signal of an organic scintillator probe consists of a scintillation signal and Cerenkov and fluorescence radiation (CFR) signal when the probe is exposed to a mega-voltage photon or electron beam. The CFR signal is usually unwanted because it comes from both the scintillator and light guide and so it is not proportional to the absorbed dose in the scintillator. A new organic scintillator detector system has been constructed for absorbed dose measurement in pulsed mega-voltage electron and photon beams that are commonly used in radiotherapy treatment, eliminating most of the CFR signal. The new detector system uses a long decay constant BC-444G (Bicron, Newbury, OH, USA) scintillator which gives a signal that can be time resolved from the prompt CFR signal so that the measured contribution of prompt signal is negligible. The response of the new scintillator detector system was compared with the measurements from a plastic scintillator detector that were corrected for the signal contribution from the CFR, and to appropriately corrected ion chamber measurements showing agreement in the 16 MeV electron beam used. PMID:12030564

Clift, M A; Johnston, P N; Webb, D V

2002-04-21

254

Assessment of drinking water radioactivity content by liquid scintillation counting: set up of high sensitivity and emergency procedures  

Microsoft Academic Search

In our institute, different procedures have been developed to measure the radioactivity content of drinking water both in normal and in emergency situations, such as those arising from accidental and terrorist events. A single radiometric technique, namely low level liquid scintillation counting (LSC), has been used. In emergency situations a gross activity screening is carried out without any sample treatment

R. Rusconi; A. Azzellino; S. Bellinzona; M. Forte; R. Gallini; G. Sgorbati

2004-01-01

255

The Lindblad equation for the decay of entanglement due to atmospheric scintillation  

NASA Astrophysics Data System (ADS)

The quantum state for the spatial degrees of freedom of photons propagating through turbulence is analyzed. The turbulent medium is modeled by a single phase screen for weak scintillation conditions and by multiple phase screens for general scintillation conditions. In the former case the process is represented by an operator product expansion, leading to an integral expression that is consistent with current models. In the latter case the evolution of the density operator is described by a first-order differential equation with respect to the propagation distance. It is shown that this differential equation has the form of a Lindblad master equation. Additionally, it is shown that this differential equation can take on the form of the infinitesimal propagation equation.

Roux, Filippus S.

2014-05-01

256

Neutron guide  

DOEpatents

A neutron guide in which lengths of cylindrical glass tubing have rectangular glass plates properly dimensioned to allow insertion into the cylindrical glass tubing so that a sealed geometrically precise polygonal cross-section is formed in the cylindrical glass tubing. The neutron guide provides easier alignment between adjacent sections than do the neutron guides of the prior art.

Greene, Geoffrey L. (Los Alamos, NM)

1999-01-01

257

A Pixelated CsI (Tl) Scintillator for CMOS-based X-ray Image Sensor  

Microsoft Academic Search

Direct and indirect imaging detectors for digital radiography have been developed during the past a few years. Among scintillators, columnar CsI(Tl) screens are used for indirect digital X-ray imaging for industrial and medical radiography. By the help of recent developments CMOS (Complementary Metal Oxide Semiconductor) is replacing the CCD (Charge Coupled Devices) in X-ray image sensor because of low operating

Bo Kyung Cha; Byoung-Jik Kim; Gyuseong Cho; Sung Chae Jeon; Jun Hyung Bae; Yong Ki Chi; Gyu-Ho Lim; Young-Hee Kim

2006-01-01

258

A scintillation counter with neutron and gamma-ray discriminators  

Microsoft Academic Search

Certain organic scintillators, notably anthracene, stilbene and ; quaterphenyl crystals and oxygen-free liquid scintillators, show an effectively ; longer scintillation decay time for heavily ionizing particles such as alpha-; particles or protons than for electrons. A scintillation counter is described ; which distinguishes fast neutrons from gammaa-rays by means of the different ; decay times of recoil proton and Compton

F. Brooks

1959-01-01

259

optics: general-purpose scintillator light response simulation code  

Microsoft Academic Search

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

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

2001-01-01

260

Some results of night-time scintillations at low latitude  

NASA Astrophysics Data System (ADS)

Ionospheric scintillation observations of VHF radio signals from FLEETSAT satellite (73 deg E longitude) at Bhopal from January 1990 to December 1990 are used to study the characteristic variations of scintillation activity. It is found that scintillation occurrence is essentially a nighttime phenomenon and daytime scintillations are very rare. Annual average nocturnal variation of percentage occurrence of scintillations shows maximum at around 2100-2200 h LT. Seasonally, scintillations are most prominent during equinoxes and least during summer. Geomagnetic disturbances tend to decrease the occurrence of scintillations in the pre-midnight period.

Kumar, Sushil; Vijay, S. K.; Gwal, A. K.

1993-06-01

261

Measurement of imaging properties of scintillating fiber optic plate  

NASA Astrophysics Data System (ADS)

Scintillating Fiber Optic Plates (SFOP) or Fiber Optic Scintillator (FOS) made with scintillating fiber-glass, were investigated for x-ray imaging. Two different samples (T x W x L = 2cm x 5cm x 5cm) were used; Sample A: 10?m fibers, Sample B: 50?m fibers both with statistically randomized light absorbing fibers placed in the matrix. A customized holder was used to place the samples in close contact with photodiodes in an amorphous silicon flat panel detector (AS1000, Varian), typically used for portal imaging. The detector has a 392?m pixel pitch and in the standard configuration uses a gadolinium oxy-sulphide (GOS) screen behind a copper plate. X-ray measurements were performed at 120kV (RQA 9 spectrum), 1MeV (5mm Al filtration) and 6MeV (Flattening Filter Free) for Sample A and the latter 2 spectra for Sample B. A machined edge was used for MTF measurements. The measurements showed the MTF degraded with increased X-ray energies because of the increase in Compton scattering. However, at the Nyquist frequency of 1.3lp/mm, the MTF is still high (FOS value vs. Cu+GOS): (a) 37% and 21% at 120kVp for the 10?m FOS and the Cu+GOS arrays, (b) 31%, 20% and 20% at 1MeV and (c) 17%, 11% and 14% at 6MeV for the 10?m FOS, 50?m FOS and the Cu+GOS arrays. The DQE(0) value comparison were (a) at 120kV ~24% and ~13 % for the 10?m FOS and the Cu+GOS arrays (b) at 1MV 10%, 10% and 7% and (c) at 6MV 12%, ~19% and 1.6% for the 10?m FOS , 50?m FOS and Cu+GOS arrays.

Zentai, George; Ganguly, Arundhuti; Star-Lack, Josh; Virshup, Gary; Hirsh, Hayley; Shedlock, Daniel; Humber, David

2014-03-01

262

Measurement of light emission in scintillation vials  

SciTech Connect

The efficiency and energy resolution of liquid scintillation counting (LSC) systems are strongly dependent on the optical characteristics of scintillators, vials, and reflectors. This article presents the results of measurements of the light-emission profile of scintillation vials. Two measurement techniques, autoradiographs and direct measurements with a photomultiplier tube, have been used to obtain light-emission distribution for standard vials of glass, etched glass and polyethylene. Results obtained with both techniques are in good agreement. For the first time, the effect of the meniscus in terms of light contribution has been numerically estimated. These results can help design LSC systems that are more efficient in terms of light collection.

Duran Ramiro, M. Teresa; Garcia-Torano, Eduardo [Laboratorio de Metrologia de Radiaciones Ionizantes, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avenida Complutense 22, 28040 Madrid (Spain)

2005-09-15

263

Fast scintillation counters with WLS bars  

SciTech Connect

The Doe collaboration is building 4608 scintillation counters to upgrade forward muon system for the next Fermilab Collider run. Each counter consists of 12.7 mm thick scintillator plate with two WLS bars along two sides for the light collection. With average 10{sup 2} photoelectrons from mip particle the counters provide time resolution below 1ns and have good energy resolution. Results of Bicron 404A scintillator and Kumarin 30 WLS aging under irradiation up to 3Mrad are presented. With specially designed magnetic shielding counters can operate in magnetic filed up to 500G.

Bezzubov, V.; Denisov, S.; Dyshkant, A.; Evdokimov, V.; Galyaev, A.; Goncharov, P.; Gurzhiev, S.; Kostritsky, A.; Kozelov, A.; Stoianova, D. [Institute for High Energy Physics, Protvino 142284 (Russian Federation); Denisov, D.; Diehl, H. T.; Ito, A. S. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States); Johns, K. [University of Arizona, Tucson, Arizona 85721 (United States)

1998-11-09

264

Cosmic-ray cascades photographed in scintillator  

NASA Technical Reports Server (NTRS)

Light produced by nuclear-electromagnetic cascades in a plastic scintillator can be photographed, and the resulting images on film used to measure both the energy content of the cascades and also the positions at which the cascades passed through the scintillator. The energy content of a cascade can be measured to 20% and its position determined to plus or minus 0.8 cm in each scintillator. Techniques for photographing the cascades and analyzing the film are described. Sample data are presented and discussed.

Barrowes, S. C.; Huggett, R. W.; Levit, L. B.; Porter, L. G.

1974-01-01

265

Imaging neutron beams with scintillating fiber faceplates  

NASA Astrophysics Data System (ADS)

An imaging system for neutron beams based on scintillating fiber faceplates is described. The scintillating fibers are made from lithium silicate glass doped with Ce 3+ using isotopically enriched 6Li. Several faceplates ranging in thickness from 1.3 to 3.2 mm have been tested using a position-sensitive photomultiplier or a Charge Injection Device camera as the photodetector. Advantages of scintillating fiber faceplates include high neutron capture efficiency, good position resolution, and the possibility of low-cost, large-area detectors.

Reeder, P. L.; Peurrung, A. J.; Richey, W. C.; Chen-Mayer, H. H.; Sharov, V. A.; Fokin, V.; Mildner, D. F. R.

1998-02-01

266

New Organic Scintillators for Neutron Detection  

SciTech Connect

This paper present the current work on neutron detection in Soltan Institute for Nuclear Studies. Lately, we have focused our research on the development of new organic scintillators including liquid scintillators for neutron detection and associated measurements. We measured liquid scintillators (also {sup 10}B-doped for thermal neutron detection){sup 3}He tubes, composites, etc. Response of the following detectors on thermal neutrons, fast neutrons and gamma radiation - the pulse shape discrimination (PSD)- has been mainly performed by means of a zero-crossing (ZC) method.

Iwanowska, Joanna; Szczeniak, Tomasz [Soltan Institute for Nuclear Studies, PL 05-400 Otwock-Swierk (Poland)

2010-01-05

267

The Borexino scintillator and solvent procurement  

NASA Astrophysics Data System (ADS)

The Borexino experiment for solar neutrino physics and other rare phenomena requires an extremely low radioactive background to disentangle the very few events due to neutrino interactions. Therefore, the Borexino scintillator has to satisfy the most stringent radiopurity requirements, being about eight orders of magnitude less radioactive than an ordinary material. This was achieved by means of scintillator purification techniques and of a special care during all the production, handling and procurement of the scintillator solvent. This paper describes the methodology and the quality control procedures that were employed during the production, handling and shipping of the solvent.

Giammarchi, Marco

2014-05-01

268

Factors determining radiation stability of plastic scintillators  

NASA Astrophysics Data System (ADS)

Polystyrene (PS) and polyvinylxylene (PVX) are the base materials for plastic scintillators. UV-Vis spectrophotometry, luminescence and EPR spectroscopy were performed on irradiated samples of PS and PVX with the p-terphenyl (TP) as primary luminophore and 1,4-di-2(5-phenyloxazolyl-1,3)benzene (POPOP) as secondary one. Dependence of the radioluminescence intensity of the scintillators on the concentration of the macroradicals formed in them in the process of irradiation was investigated. Dose dependence of the radiation stability of scintillators is discussed.

Gunder, O. A.; Voronkina, N. I.; Barashkov, N. N.; Milinchuk, V. K.; Jdanov, G. S.

1995-07-01

269

Single crystal scintillator plates used for light weight material X-ray radiography  

NASA Astrophysics Data System (ADS)

Very thin scintillator imaging plates have recently become of great interest. In high resolution X-ray projection imaging, very thin scintillators of about 5-20 micrometres are used to achieve high spatial resolution. Such thin screens are mainly used in micro-CT and nano-CT systems with either micro-focus X-ray tubes or with synchrotron sources. This work deals with a high resolution CCD camera in connection with an optical system and different single crystal scintillators in application for low energy X-ray micro-radiography. The thin screens used were prepared by mechanical polishing from Y3Al5O12 or Lu3Al5O12 single crystals. The screens can be used in equipment for the detection of different kinds of radiation and particles (UV, VUV, electrons or ions or their beams, X- or gamma-rays). A high resolution open type micro-focus X-ray tube was used to achieve the high resolution. The results show that the single crystal plates exhibit high spatial resolution and high sensitivity to low energy X-rays resulting in high image contrast. The use of the plates is highly suitable for light weight (low Z) material X-ray radiography. The resolution achieved is demonstrated using a test grid. Several light weight objects are imaged using the thin plates.

Tous, J.; Blazek, K.; Nikl, M.; Mares, J. A.

2013-03-01

270

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

PubMed

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

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

2012-06-01

271

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

SciTech Connect

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

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

2011-01-01

272

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

273

Screening Jews and genes: a consideration of the ethics of genetic screening within the Jewish community: challenges and responses.  

PubMed

Screening for genetic disorders, particularly Tay-Sachs Disease, has been traditionally welcome by the Jewish community. I review the history of genetic screening among Jews and the views from the Jewish tradition on the subject, and then discuss ethical challenges of screening and the impact of historical memories upon future acceptance of screening programs. Some rational principles to guide future design of genetic screening programs among Jews are proposed. PMID:10464669

Levin, M

1999-01-01

274

The Beginning Filmmaker's Guide to Directing.  

ERIC Educational Resources Information Center

This guide, intended as a manual for the beginning director, educational filmmaker, or film school student, provides instruction for attending to the progressive elements of cinematographic craft, from the initial idea to the screen. The guide examines the structure of the script, aspects of acting and working with actors, music and sound, camera…

Harmon, Renee

275

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

276

A Monte Carlo investigation of Swank noise for thick, segmented, crystalline scintillators for radiotherapy imaging  

SciTech Connect

Thick, segmented scintillating detectors, consisting of 2D matrices of scintillator crystals separated by optically opaque septal walls, hold considerable potential for significantly improving the performance of megavoltage (MV) active matrix, flat-panel imagers (AMFPIs). Initial simulation studies of the radiation transport properties of segmented detectors have indicated the possibility of significant improvement in DQE compared to conventional MV AMFPIs based on phosphor screen detectors. It is therefore interesting to investigate how the generation and transport of secondary optical photons affect the DQE performance of such segmented detectors. One effect that can degrade DQE performance is optical Swank noise (quantified by the optical Swank factor I{sub opt}), which is induced by depth-dependent variations in optical gain. In this study, Monte Carlo simulations of radiation and optical transport have been used to examine I{sub opt} and zero-frequency DQE for segmented CsI:Tl and BGO detectors at different thicknesses and element-to-element pitches. For these detectors, I{sub opt} and DQE were studied as a function of various optical parameters, including absorption and scattering in the scintillator, absorption at the top reflector and septal walls, as well as scattering at the side surfaces of the scintillator crystals. The results indicate that I{sub opt} and DQE are only weakly affected by absorption and scattering in the scintillator, as well as by absorption at the top reflector. However, in some cases, these metrics were found to be significantly degraded by absorption at the septal walls and scattering at the scintillator side surfaces. Moreover, such degradations are more significant for detectors with greater thickness or smaller element pitch. At 1.016 mm pitch and with optimized optical properties, 40 mm thick segmented CsI:Tl and BGO detectors are predicted to provide DQE values of {approx}29% and 42%, corresponding to improvement by factors of {approx}29 and 42, respectively, compared to that of conventional MV AMFPIs.

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

2009-07-15

277

High-Selectivity Scintillation Spectrometer of Antineutrinos.  

National Technical Information Service (NTIS)

A new design principle for a spectrometer of reactor antineutrinos nu -tilde/sub e/ using reverse beta -decay reaction on proton is proposed. The detector consists of alternating plates of solid organic and heavy inorganic scintillators. Reaction positron...

V. I. Kopejkin L. A. Mikaehlyan

1987-01-01

278

Scintillating glass fiber-optic neutron sensors.  

National Technical Information Service (NTIS)

Pacific Northwest Laboratory (PNL) has fabricated cerium-activated lithium silicate scintillating fibers via a hot-downdraw process. These fibers, which, as produced, typically have a transmission length (e(sup (minus)1) length) of greater than 2 meters, ...

K. H. Abel R. J. Arthur M. Bliss

1994-01-01

279

Radiation damage and annealing of scintillating glasses  

Microsoft Academic Search

Measurements of the radiation hardness, of cerium and terbium doped scintillating glasses, are reported in this work. Annealing tests have demonstrated the efficacy of violet-blue light in the repairing of radiation damage.

P. Pavan; G. Zanella; R. Zannoni; P. Polato

1991-01-01

280

Extruded Plastic Scintillator for MINERvA.  

National Technical Information Service (NTIS)

An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. Since po...

A. Pla-Dalmau A. D. Bross V. V. Rykalin B. M. Wood

2005-01-01

281

The Scintillating Optical Fiber Isotope Experiment  

NASA Technical Reports Server (NTRS)

This paper describes the Scintillating Optical Fiber Isotope Experiment (SOFIE) which is being developed by Washington University and the University of New Hampshire to study the abundances of cosmic ray isotopes in the iron charge region. This detector system is a Cerenkov-Range-dE/dx experiment and utilizes range and trajectory detectors made of scintillating optical fibers, a fused silica Cerenkov counter, and plastic scintillator dE/dx counters to determine the charge and mass of cosmic ray nuclei. A brief description of the balloon flight instrument presently being developed will be given followed by initial results of an engineering model calibration at the LBL Bevalac heavy ion accelerator. In addition a brief discussion of the potential of scintillating fiber trajectory detectors for use in experiments requiring precise trajectory determination such as those being planned for the NASA Particle Astrophysics Magnet Facility (Astromag) program is presented.

Binns, W. Robert

1988-01-01

282

Study of rare-earth-doped scintillators  

NASA Astrophysics Data System (ADS)

Scintillators are widely used in radiation detection applications in basic science and industry. Scintillators are generally solids and consist of an emission center and a host lattice. Especially in medical applications that detect high-energy photons, the emission centers are rare-earth (RE) ions, mostly Ce3+. However, recently Pr3+ also exhibited fast 5d-4f emission and became an alternative to Ce3+. In X-ray computed tomography, a scintillation decay time on the order of microseconds is acceptable, and other rare-earth ions such as Nd3+, Eu2+, Ho3+, Er3+, and Tm3+ are candidates for the emission center. The characteristics of these inorganic materials and their advantages and disadvantages for scintillators will be discussed.

Yanagida, Takayuki

2013-09-01

283

F Layer Scintillations and the Aurora.  

National Technical Information Service (NTIS)

Defense Meteorological Satellite Program photographs of the aurora are correlated with the scintillation of radio signals from both low-altitude and synchronous satellites. Measurements from several stations ranging from subauroral to auroral locations sh...

E. Martin J. Aarons

1975-01-01

284

Coping with plastic scintillators in nuclear safeguards  

SciTech Connect

Plastic scintillators offer several advantages for nuclear safeguards research and technology to those who design, assemble, encapsulate, and calibrate detectors from raw materials that are commercially available. These large, inexpensive detectors have good spatial uniformity and good high-energy gamma-ray response. Uniform light collection is obtained with a light pipe attached to a polished scintillator wrapped with aluminum foil. Best low-energy response is obtained by applying a variance analyzer to select the low-energy bias level.

Fehlau, P.E.; Brunson, G.S.

1982-01-01

285

Scintillating-glass-fiber neutron sensors  

Microsoft Academic Search

Cerium-doped lithium-silicate glass fibers have been developed at Pacific Northwest Laboratory (PNL) for use as thermal neutron detectors. By using highly-enriched 6Li, these fibers efficiently capture thermal neutrons and produce scintillation light that can be detected at the ends of the fibers. Advantages of scintillating fibers over 3He or BF3 proportional tubes include flexibility in geometric configuration, ruggedness in high-vibration

K. H. Abel; R. J. Arthur; M. Bliss; D. W. Brite; R. L. Brodzinski; R. A. Craig; B. D. Geelhood; D. S. Goldman; J. W. Griffin; R. W. Perkins; P. L. Reeder; W. R. Richey; K. A. Stahl; D. S. Sunberg; R. A. Warner; N. A. Wogman; M. J. Weber

1994-01-01

286

The Response of Plastic Scintillators to Protons  

Microsoft Academic Search

Plastic scintillators were found to obey the formula (dS\\/dr) = (A dE\\/dr)\\/; (l + kB dE\\/dr) quite accurately. An NE.102 type plastic scintillator, 2 in. in ; diameter and 1\\/2 in. thick, was used. The values obtained for the constant kB ; were found to agree quite well with values of kB obtained bv Boreli and Grimeland. ; (C.J.G.);

H. C. Evans; E. H. Bellamy

1959-01-01

287

Coping with plastic scintillators in nuclear safeguards  

Microsoft Academic Search

Plastic scintillators offer several advantages for nuclear safeguards research and technology to those who design, assemble, encapsulate, and calibrate detectors from raw materials that are commercially available. These large, inexpensive detectors have good spatial uniformity and good high-energy gamma-ray response. Uniform light collection is obtained with a light pipe attached to a polished scintillator wrapped with aluminum foil. Best low-energy

P. E. Fehlau; G. S. Brunson

1983-01-01

288

A new radiation-resistant plastic scintillator  

Microsoft Academic Search

A radiation-resistant plastic scintillator has been developed to withstand the high radiation dose regions that will be present in the proposed SSC and LHC accelerators. The base is a highly transparent and radiation resistant polysiloxane plastic. This has been doped with a variety of radiation resistant fluors. The resultant scintillators have been shown to be highly resistant to ⁶°Co gamma

M. Bowen; S. Majewski; D. Pettey; J. Walker; R. Wojcik; C. Zorn

1989-01-01

289

Ternary liquid scintillator for optical fiber applications  

DOEpatents

A multicomponent liquid scintillator solution for use as a radiation-to-light converter in conjunction with a fiber optic transmission system. The scintillator includes a quantity of 5-amino-9-diethylaminobenz (a) phenoxazonium nitrate (Nile Blue Nitrate) as a solute in a fluor solvent such as benzyl alcohol. The use of PPD as an additional solute is also disclosed. The system is controllable by addition of a suitable quenching agent, such as phenol.

Franks, Larry A. (Santa Barbara, CA); Lutz, Stephen S. (Santa Barbara, CA)

1982-01-01

290

Liquid scintillators for optical fiber applications  

DOEpatents

A multicomponent liquid scintillator solution for use as a radiation-to-light converter in conjunction with a fiber optic transmission system. The scintillator includes a quantity of 1, 2, 4, 5, 3H, 6H, 1 OH, tetrahydro-8-trifluoromethyl (1) benzopyrano (9, 9a, 1-gh) quinolizin-10-one (Coumarin) as a solute in a fluor solvent such as benzyl alcohol or pseudo-cumene. The use of BIBUQ as an additional or primary solute is also disclosed.

Franks, Larry A. (Santa Barbara, CA); Lutz, Stephen S. (Santa Barbara, CA)

1982-01-01

291

Liquid scintillators for optical-fiber applications  

DOEpatents

A multicomponent liquid scintillator solution for use as a radiation-to-light converter in conjunction with a fiber optic transmission system. The scintillator includes a quantity of 1, 2, 4, 5, 3H, 6H, 1 OH, tetrahydro-8-trifluoromethyl (1) benzopyrano (9, 9a, 1-gh) quinolizin-10-one (Coumarin) as a solute in a fluor solvent such as benzyl alcohol or pseudo-cumene. The use of BIBUQ as an additional or primary solute is also disclosed.

Franks, L.A.; Lutz, S.S.

1981-06-01

292

Crystal growth and scintillation properties of strontium iodide scintillators  

SciTech Connect

Single crystals of SrI{sub 2}:Eu and SrI{sub 2}:Ce/Na were grown from anhydrous iodides by the vertical Bridgman technique in evacuated silica ampoules. Growth rates were of the order of 5-30 mm/day. Radioluminescence spectra of SrI{sub 2}:Eu and SrI{sub 2}:Ce/Na exhibit a broad band due to Eu{sup 2+} and Ce{sup 3+} emission, respectively. The maximum in the luminescence spectrum of SrI{sub 2}:Eu is found at 435 nm. The spectrum of SrI{sub 2}:Ce/Na exhibits a doublet peaking at 404 and 435 nm attributed to Ce{sup 3+} emission, while additional impurity - or defected - related emission is present at approximately 525 nm. The strontium iodide scintillators show very high light yields of up to 120,000 photons/MeV, have energy resolutions down to 3% at 662 keV (Full Width Half Maximum) and exhibit excellent light yield proportionality with a standard deviation of less than 5% between 6 and 460 keV.

van Loef, Edgar; Wilson, Cody; Cherepy, Nerine; Payne, Steven; Choong, Woon-Seng; Moses, William W.; Shah, Kanai

2009-06-01

293

A Guide to Desktop Videoconferencing.  

ERIC Educational Resources Information Center

This document presents a step-by-step guide to using three desktop videoconferencing applications: CU-SeeMe, iVisit, and NetMeeting. First, hardware and software recommendations for PC-based and Macintosh systems are provided. Illustrations of sample screens accompany the text for each application. The following additional considerations for…

Maring, Gerald H.; Levy, Erik W.

294

Scintillation Hole Observed by FORMOSAT-3/COSMIC  

NASA Astrophysics Data System (ADS)

Ionospheric scintillations can significantly disturb satellite positioning, navigation, and communication. FORMOSAT-3/COSMIC provides the first 3-D global observation by solo instrument (radio occultation experiment, GOX). The GPS L-band amplitude fluctuation from 50Hz signal is received and recorded by F3/C GOX to calculate S4-index from 50-800km altitude. The global F3/C S4 index are subdivided and examined in various latitudes, longitudes, altitudes, and seasons during 2007-2012. The F-region scintillations in the equatorial and low-latitude ionosphere start around post-sunset period and often persist till post-midnight hours (0300 MLT, magnetic local time) during the March and September equinox as well as December Solstice seasons. The E-region scintillations reveal a clear solar zenith effect and yield pronounced intensities in mid-latitudes during the Summer Solstice seasons, which are well correlated with occurrences of the sporadic E-layer. It is interesting to find there is no scintillation, which is termed "scintillation hole", in the E region ranging from 80 to 130km altitude over the South Africa region, and become the most pronounced in November-January (December Solstice seasons or summer months). Other space-borne and ground based observations are use to confirm the existence of the scintillation hole.

Chen, Shih Ping; Yenq Liu, Jann; Krishnanunni Rajesh, Panthalingal

2013-04-01

295

Development of Novel Polycrystalline Ceramic Scintillators  

SciTech Connect

For several decades most of the efforts to develop new scintillator materials have concentrated on high-light-yield inorganic single-crystals while polycrystalline ceramic scintillators, since their inception in the early 1980 s, have received relatively little attention. Nevertheless, transparent ceramics offer a promising approach to the fabrication of relatively inexpensive scintillators via a simple mechanical compaction and annealing process that eliminates single-crystal growth. Until recently, commonly accepted concepts restricted the polycrystalline ceramic approach to materials exhibiting a cubic crystal structure. Here, we report our results on the development of two novel ceramic scintillators based on the non-cubic crystalline materials: Lu SiO:Ce (LSO:Ce) and LaBr:Ce. While no evidence for texturing has been found in their ceramic microstructures, our LSO:Ce ceramics exhibit a surprisingly high level of transparency/ translucency and very good scintillation characteristics. The LSO:Ce ceramic scintillation reaches a light yield level of about 86% of that of a good LSO:Ce single crystal, and its decay time is even faster than in single crystals. Research on LaBr:Ce shows that translucent ceramics of the high-light-yield rare-earth halides can also be synthesized. Our LaBr:Ce ceramics have light yields above 42 000 photons/MeV (i.e., 70%of the single-crystal light yield).

Wisniewska, Monika [ORNL; Boatner, Lynn A [ORNL; Neal, John S [ORNL; Jellison Jr, Gerald Earle [ORNL; Ramey, Joanne Oxendine [ORNL; North, Andrea L [ORNL; Wisniewski, Monica [Oak Ridge National Laboratory (ORNL); Payzant, E Andrew [ORNL; Howe, Jane Y [ORNL; Lempicki, Aleksander [ALEM Associates, Boston; Brecher, Charlie [ALEM Associates, Boston; Glodo, J. [Radiation Monitoring Devices, Watertown, MA

2008-01-01

296

Screen Time  

NSDL National Science Digital Library

This game asks you a series of questions about how much time you spend in front of a screen, not being active. It begins by pointing out that since we spend a lot of time in front of computer screens at work or school, additional time at home can really affect how healthy we are. It asks how much time you spend watching TV, playing computer games, and using the computer each day. It then adds up the total amount of screen time you spend every day, and calculates how many hours you spend a year in front of a screen. It also tells you if that's a healthy amount, and suggests ways to stay active while in front of screens.

Omsi

2007-01-01

297

Genetic screening  

PubMed Central

Abstract OBJECTIVE To provide a primer for primary care professionals who are increasingly called upon to discuss the growing number of genetic screening services available and to help patients make informed decisions about whether to participate in genetic screening, how to interpret results, and which interventions are most appropriate. QUALITY OF EVIDENCE As part of a larger research program, a wide literature relating to genetic screening was reviewed. PubMed and Internet searches were conducted using broad search terms. Effort was also made to identify the gray literature. MAIN MESSAGE Genetic screening is a type of public health program that is systematically offered to a specified population of asymptomatic individuals with the aim of providing those identified as high risk with prevention, early treatment, or reproductive options. Ensuring an added benefit from screening, as compared with standard clinical care, and preventing unintended harms, such as undue anxiety or stigmatization, depends on the design and implementation of screening programs, including the recruitment methods, education and counseling provided, timing of screening, predictive value of tests, interventions available, and presence of oversight mechanisms and safeguards. There is therefore growing apprehension that economic interests might lead to a market-driven approach to introducing and expanding screening before program effectiveness, acceptability, and feasibility have been demonstrated. As with any medical intervention, there is a moral imperative for genetic screening to do more good than harm, not only from the perspective of individuals and families, but also for the target population and society as a whole. CONCLUSION Primary care professionals have an important role to play in helping their patients navigate the rapidly changing terrain of genetic screening services by informing them about the benefits and risks of new genetic and genomic technologies and empowering them to make more informed choices.

Andermann, Anne; Blancquaert, Ingeborg

2010-01-01

298

Preparation of paper scintillator for detecting 3H contaminant.  

PubMed

Liquid scintillator (LS)-encapsulated silica was prepared by the sol-gel method and then was added dropwise onto a wipe paper to form a paper scintillator. First, the efficiencies of wipe were determined for both the paper scintillator and the wipe paper using a liquid scintillation counter (LSC). The efficiencies of wipe using the paper scintillator and the wipe paper were 88 and 36 %, respectively. The detection efficiencies were 5.5 % for the paper scintillator, 46 % for the wipe paper using an LS and 0.08 % for the (3)H/(14)C survey meter, respectively, compared with that of a melt-on scintillator of 47 %. Second, an (3)H contaminant on the paper scintillator was successfully detected using a photomultiplier without an LSC or an (3)H/(14)C survey meter. Finally, the paper scintillator was able to detect beta rays of the (3)H contaminant easily without an LS. PMID:23554426

Miyoshi, Hirokazu; Ikeda, Toshiji

2013-09-01

299

Colon cancer screening  

MedlinePLUS

Screening for colon cancer; Colonoscopy - screening; Sigmoidoscopy - screening; Virtual colonoscopy - screening ... Colon cancer screening can detect polyps and early cancers in the intestines. This type of screening can find ...

300

The equatorial ionospheric scintillations during geomagnetic storms  

NASA Astrophysics Data System (ADS)

Geomagnetic storms and disturbances are thought to play an important role for initiation of the ionospheric scintillations. Scintillation manifest itself in rapid fluctuation of the phase and intensity of a radio signal that has passed through the Earth's ionosphere, typically on a satellite-to-ground propagation channel. Mechanisms of ionospheric scintillation are better understood than its morphology and serious efforts were made to find the empirical relationships in terms of different geomagnetic indices for their forcasting. Such relationships can help to avoid blackouts and distortions in VLF communication due to ionospheric irregularities. We used the different geomagnetic indices, the ionospheric parameters, and the Bz-component of the interplanetary magnetic field (IMF) to study scintillation activity at the dip latitudes. The relationship between the equatorial ionospheric scintillations and the IMF Bz, Dst, Kp, AU, and AL indices is demonstrated. It is shown that in parallel with much used of Dst- index other indices are also suitable for study of scintillation activity. For example, Kp as planetary index carries information about auroral electrojets also and we can see that no scintillation activity when Kp decreases during positive IMF Bz. This means that the auroral electrojets depicted by the AU, and AL-indices and connected with the field-aligned currents (FAC) are decreased and moved to pole ward. The positive IMF Bz is likely to be the factor that inhibits the equator ward penetration of the high latitude electric field. The negative IMF Bz enhances the auroral electric fields and they can penetrate to the equatorial ionosphere. The examples presented in our study allow us to assume that the southward IMF Bz by the Region 1 FAC can form an additional eastward current system at the equatorial ionosphere. Under these conditions the virtual height h'F rises to high altitudes and when it drops the scintillations can be generated. It may be safely suggested that source of this phenomenon is the solar wind electric field responcible for the auroral and equatorial ionosphere coupling. Other processes such as tides, earthquakes etc. can change the ionospheric height also and may play a role in the generation of the ionospheric scintillations. From a practical point of view, the relationships between the solar wind and the ionospheric parameters can be used for the prediction of scintillations, if one takes into account the time delay between the IMF Bz and the equatorial ionospheric data.

Biktash, L.

301

Evaluation of characteristics of x-ray phosphors and hybrid scintillators  

SciTech Connect

Glass x-ray scintillators produce very high resolution images but suffer diminished brightness at x-ray energies below about 150 kV. This produces a loss in effective imaging due to the very low light flux, just at energies where many high resolution applications require the maximum image fidelity. Many phosphors produce substantially more light at these energy levels, but lack the resolution needed for critical industrial applications. A family of hybrid scintillators consisting of a scintillating fiber-optic base coupled to a thin coating of a high resolution phosphor is being developed. To facilitate evaluation of these hybrids and to measure their performance compared to other alternatives, a specialized real time x-ray imaging system was constructed and integrated with a microfocus x-ray source. This imaging system is described, and the results of a program to evaluate the brightness, resolution, and contrast sensitivity of a number of glass scintillators, phosphors, and hybrid imaging screens is presented.

Winter, John M. Jr. [Center for Nondestructive Evaluation, Johns Hopkins University, Baltimore, Md., 21218 (United States); Jones, Thomas S. [Industrial Quality, Inc., 640 E. Diamond Ave, Suite C, Gaithersburg, Md., 20877 (United States)

1999-12-02

302

Numbers of scintillation photons produced in NaI(Tl) and plastic scintillator by gamma rays  

SciTech Connect

The W[sub s]-value, which is defined as an average energy expended per scintillation photon, was determined to be 17.2 [+-] 0.40 eV for a NaI(Tl) phosphor and 60.8 [+-] 4.3 eV for a plastic scintillator (NE-102A). Those were obtained from the numbers of photoelectrons measured with several combinations of a photomultiplier tube and a NaI(Tl) or a NE-102A scintillator. The number of photoelectrons, which was measured by the photomultiplier tube as a vacuum photodiode, was converted to the number of scintillation photons by using an averaged quantum efficiency (Q[sub e]) of each photomultiplier photocathode and a calculated collection efficiency (f[sub c]) of the scintillation photons at the photocathode. However, the above values do not include the uncertainties due to the not known exact emission spectra and the photomultiplier response curves.

Miyajima, M.; Sasaki, S.; Tawara, H. (National Lab. for High Energy Physics, Tsukuba (Japan))

1993-08-01

303

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

SciTech Connect

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

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

2011-07-01

304

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

SciTech Connect

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

Lacroix, Frederic; Archambault, Louis; Gingras, Luc; Guillot, Mathieu; Beddar, A. Sam; Beaulieu, Luc [Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec, G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec, Quebec G1R2J6 (Canada); Department of Radiation Physics, University of Texas M. D. 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, Quebec G1R2J6 (Canada); Department of Radiation Physics, University of Texas M. D. 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, Quebec G1R2J6 (Canada)

2008-08-15

305

TORCH screen  

MedlinePLUS

... different infections in a newborn. TORCH stands for toxoplasmosis , rubella , cytomegalovirus, herpes simplex, and HIV, but it ... used to screen infants for infections such as toxoplasmosis, cytomegalovirus, herpes simplex, syphilis and others. These infections ...

306

Hypertension screening  

NASA Technical Reports Server (NTRS)

An attempt was made to measure the response to an announcement of hypertension screening at the Goddard Space Center, to compare the results to those of previous statistics. Education and patient awareness of the problem were stressed.

Foulke, J. M.

1975-01-01

307

Vision Screening  

MedlinePLUS

... office. Some community screenings use this method. Corneal light reflex testing This simple test can be performed ... focuses on a penlight, the position of the light reflection from the front surface (cornea) of the ...

308

Airport Screening  

MedlinePLUS

... Available at http:// www.radiationanswers.org/radiation-blog/Airport_xray_scanners.html . Accessed 7 January 2011. Health Physics Society. Use of ionizing radiation for security screening individuals [online]. Health Physics Society Position Statement. ...

309

Ripcorder Screen  

NSDL National Science Digital Library

The Ripcorder Screen application allows users to create movies from their Macs' on-screen activities. The application will capture whatever is played on the display and transform it into a QuickTime movie. This can be most useful for users who would like to share information with colleagues or friends seeking to learn more about a particular computer operation or process. This version is compatible with all operating systems running Mac OS X 10.7 and newer.

2012-11-06

310

Prenatal screening  

Microsoft Academic Search

This report discusses the role of prenatal screening in preventing congenital abnormalities or, when prevention is not possible,\\u000a in avoiding the conception or the birth of those who would have untreatable abnormalities. Women who are found by screening\\u000a not to be immune to rubella can be safely vaccinated prior to pregnancy; those found to be at risk of having children

Neil A. Holtzman

1990-01-01

311

Radar detection during scintillation. Technical report  

SciTech Connect

Electromagnetic signals that propagate through a disturbed region of the ionosphere can experience scattering which can cause fluctuations in the received amplitude, phase, and angle-of-arrival. This report considers the performance of a radar that must operate through a disturbed propagation environment such as might occur during strong equatorial scintillation, during a barium release experiment or after a high altitude nuclear detonation. The severity of the channel disturbance is taken to range from weak scattering where the signal quadrature components are uncorrelated Gaussian variates. The detection performance of noncoherent combining is compared to that of double threshold (M out of N) combining under various levels of scintillation disturbance. Results are given for detection sensitivity as a function of the scintillation index and the ratio of the radar hopping bandwidth to the channel bandwidth. It is shown that both types of combining can provide mitigation of fading, and that noncoherent combining generally enjoys an advantage in detection sensitivity of about 2 dB. This work serves as a quantitative guideline to the advantages and disadvantages of certain types of detection strategies during scintillation and is, therefore, useful in the radar design process. However, a detailed simulation of the radar detection algorithms is necessary to evaluate a radar design strategy to predict performance under scintillation conditions.

Knepp, D.L.; Reinking, J.T.

1990-04-01

312

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

313

Investigating the temporal resolution limits of scintillation detection from pixellated elements: comparison between experiment and simulation.  

PubMed

This study investigates the physical limitations involved in the extraction of accurate timing information from pixellated scintillation detectors for positron emission tomography (PET). Accurate physical modeling of the scintillation detection process, from scintillation light generation through detection, is devised and performed for varying detector attributes, such as the crystal element length, light yield, decay time and surface treatment. The dependence of light output and time resolution on these attributes, as well as on the photon interaction depth (DoI) of the annihilation quanta within the crystal volume, is studied and compared with experimental results. A theoretical background which highlights the importance of different time blurring factors for instantaneous ('ideal') and exponential ('realistic') scintillation decay is developed and compared with simulated data. For the case of a realistic scintillator, our experimental and simulation findings suggest that dependence of detector performance on DoI is more evident for crystal elements with rough ('as cut') compared to polished surfaces (maximum observed difference of 64% (25%) and 22% (19%) in simulation (measurement) for light output and time resolution, respectively). Furthermore we observe distinct trends of the detector performance dependence on detector element length and surface treatment. For short crystals (3 × 3 × 5 mm(3)) an improvement in light output and time resolution for 'as cut' compared to polished crystals is observed (3% (7%) and 9% (9%) for simulation (measurement), respectively). The trend is reversed for longer crystals (3 × 3 × 20 mm(3)) and an improvement in light output and time uncertainty for polished compared to 'as cut' crystals is observed (36% (6%) and 40% (20%) for simulation (measurement), respectively). The results of this study are used to guide the design of PET detectors with combined time of flight (ToF) and DoI features. PMID:21239845

Spanoudaki, V Ch; Levin, C S

2011-02-01

314

Glass and phosphor scintillators for x-ray imaging  

SciTech Connect

In x-ray imaging, many combinations of scintillators and detectors are used for a variety of reasons. This paper reviews several scintillators currently used in x-ray imaging systems in medical and non-destructive testing (NDT) applications.

Ellis, John [Collimated Holes, Inc., 460 Division Street, Campbell, California 95008 (United States)

1998-11-09

315

Isotopic response with small scintillator based gamma-ray spectrometers  

DOEpatents

The intrinsic background of a gamma ray spectrometer is significantly reduced by surrounding the scintillator with a second scintillator. This second (external) scintillator surrounds the first scintillator and has an opening of approximately the same diameter as the smaller central scintillator in the forward direction. The second scintillator is selected to have a higher atomic number, and thus has a larger probability for a Compton scattering interaction than within the inner region. Scattering events that are essentially simultaneous in coincidence to the first and second scintillators, from an electronics perspective, are precluded electronically from the data stream. Thus, only gamma-rays that are wholly contained in the smaller central scintillator are used for analytic purposes.

Madden, Norman W. (Sparks, NV); Goulding, Frederick S. (Lafayette, CA); Asztalos, Stephen J. (Oakland, CA)

2012-01-24

316

Radiation effects on organic scintillators: Studies of color center annealing.  

National Technical Information Service (NTIS)

The interaction of ionizing radiation with organic, polymer-based scintillators results in the discoloration of the material, which reduces the scintillation efficiency. This phenomenon can be described in terms of two types of color centers: annealable a...

R. L. Clough J. S. Wallace

1990-01-01

317

Ruggedized ZnS(Ag)/epoxy alpha scintillation detector.  

National Technical Information Service (NTIS)

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

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

1990-01-01

318

Fiber-Optical Light Collection from Scintillation Calorimeters.  

National Technical Information Service (NTIS)

A method is described for collecting light from scintillation counter calorimeters by means of an optical fiber connected to a wave length shifter, covering the edge of a scintillation plate. The optical fiber passes between continuous metallic plates and...

V. I. Kryshkin A. I. Ronzhin

1985-01-01

319

The MICE scintillating-fibre tracker  

NASA Astrophysics Data System (ADS)

The international Muon Ionization Cooling Experiment (MICE) collaboration will carry out a systematic investigation of the ionization cooling of a muon beam. An ionization cooling channel is required to compress the phase-space volume occupied by the muon beam prior to acceleration in the baseline conceptual designs for both the Neutrino Factory and the Muon Collider. Muons entering and leaving the cooling channel will be measured in two solenoidal spectrometers, each of which is instrumented with a scintillating-fibre tracker. Each tracker is composed of five planar scintillating fibre stations, each station being composed of three planar layers of 350 micron scintillating fibres. The devices will be read out using the Visible Light Photon Counters (VLPCs) developed for use in the D0 experiment at the Tevatron. The design of the system will be presented along with the status of the tracker-construction project. The expected performance of prototypes of the full tracker will be summarised.

Matsushita, T.

2008-06-01

320

Nanocrystal-based Scintillators for Radiation Detection  

NASA Astrophysics Data System (ADS)

Several metal chalcogenides (e.g., ZnS, CdSe/ZnS) are known to be highly efficient scintillators. Concerns related to the use of these commercially available inorganic compounds (particle size: ?m) include their low solubilities in organic and polymeric matrices. Their preparation in inorganic matrices, such as sol-gels, results in non-transparent gels, thus lowering their efficiency as scintillating devices. By reducing their particle sizes from commonly used micrometer- into nanometer-size regimes, their optical properties and solubilities in both polar and nonpolar solvents can be controlled. The combination of sol-gel technique and the chemistry of inorganic nanocrystalline quantum dots will be demonstrated as a powerful method in preparing scintillating devices.

Dai, Sheng; Saengkerdsub, Suree; Im, Hee-Jung; Stephan, Andrew C.; Mahurin, Shannon M.

2002-10-01

321

Monte Carlo investigations of the effect of beam divergence on thick, segmented crystalline scintillators for radiotherapy imaging  

PubMed Central

The use of thick segmented scintillators in electronic portal imagers offers the potential for significant improvement in x-ray detection efficiency compared to conventional phosphor screens. Such improvement substantially increases the detective quantum efficiency (DQE), leading to the possibility of achieving soft-tissue visualization at clinically-practical (i.e. low) doses using megavoltage (MV) cone-beam computed tomography. While these DQE increases are greatest at zero spatial frequency, they are diminished at higher frequencies as a result of degradation of spatial resolution due to lateral spreading of secondary radiation within the scintillator – an effect that is more pronounced for thicker scintillators. The extent of this spreading is even more accentuated for radiation impinging the scintillator at oblique angles of incidence due to beam divergence. In this paper, Monte Carlo simulations of radiation transport, performed to investigate and quantify the effects of beam divergence on the imaging performance of MV imagers based on two promising scintillators (BGO and CsI:T1), are reported. In these studies, 10 – 40 mm thick scintillators, incorporating low-density polymer, or high-density tungsten septal walls were examined for incident angles corresponding to that encountered at locations up to ~15 cm from the central beam axis (for an imager located 130 cm from a radiotherapy x-ray source). The simulations demonstrate progressively more severe spatial resolution degradation (quantified in terms of the effect on modulation transfer function) as a function of increasing angle of incidence (as well as of scintillator thickness). Since the noise power behavior was found to be largely independent of incident angle, the dependence of the DQE on incident angle is therefore primarily determined by the spatial resolution. The observed DQE degradation suggests that 10 mm thick scintillators are not strongly affected by beam divergence for detector areas up to ~30 × 30 cm2. For thicker scintillators, the area that is relatively unaffected is significantly reduced, requiring a focused scintillator geometry in order to preserve spatial resolution, and thus DQE.

Wang, Yi; El-Mohri, Youcef; Antonuk, Larry E.; Zhao, Qihua

2010-01-01

322

New results on radiation damage studies of plastic scintillators  

Microsoft Academic Search

This article presents a comparative study of scintillation and radiation characteristics for a series of new and known plastic scintillators. About 70 new scintillators have been measured. Polystyrene scintillators containing 20% 1-methylnaphthalene + 2% pTP + 0.05% POPOP and 20% 1-methylnaphthalene + 2% pTP + 0.05% POPOP + 0.02% K-27 revealed the maximum radiation resistance, about 7–9 Mrad.

V. G. Vasil'chenko; V. G. Lapshin; A. I. Peresypkin; A. A. Konstantinchenko; A. I. Pyshchev; V. M. Shershukov; B. V. Semenov; A. S. Solov'ev

1996-01-01

323

The Relative Performances of Large Volume Plastic and Liquid Scintillators  

Microsoft Academic Search

The performances are compared of similar large volumes (20 in.×10 in.×6 in.) of (1) a plastic scintillator (NE 101), (2) a conventional liquid scintillator (PPO plus POPOP in toluene), and (3) a lead-loaded liquid scintillator (NE 314). A description is given of the aluminium-casting oval test unit in which scintillations are viewed by two 5 in. diameter photomultipliers, the output

P. M. Bird; P. R. J. Burch

1958-01-01

324

A new plastic scintillator with large stokes shift  

Microsoft Academic Search

We have developed a new plastic scintillator with the novel characteristic of highly localized light emission; scintillation and wavelength shifting take place within a few tens of micrometers of the primary ionization. The new scintillator consists of a scintillating polymer base [polyvinyl toluene (PVT) or polystyrene (PS)] doped with a single wavelength shifter, 1-phenyl-3-mesityl-2-pyrazoline (PMP), which has an exceptionally large

P. Destruel; M. Taufer; C. D'Ambrosio; C. da Via; J. P. Fabre; J. Kirkby; H. Leutz

1989-01-01

325

Let dependence of scintillation yields in liquid argon  

Microsoft Academic Search

Scintillation yields (scintillation intensity per unit absorbed energy) in liquid argon for ionizing particles are reviewed as a function of LET for the particles. The maximum scintillation yield, which is obtained for relativistic heavy ions from Ne to La, is about 1.2 times larger than that for gamma rays in NaI(Tl) crystal. In the low LET region, the scintillation yields

Tadayoshi Doke; Henry J. Crawford; Akira Hitachi; Jun Kikuchi; Peter J. Lindstrom; Kimiaki Masuda; Eido Shibamura; Tan Takahashi

1988-01-01

326

New results on radiation damage studies of plastic scintillators  

NASA Astrophysics Data System (ADS)

This article presents a comparative study of scintillation and radiation characteristics for a series of new and known plastic scintillators. About 70 new scintillators have been measured. Polystyrene scintillators containing 20% 1-methylnaphthalene + 2% pTP + 0.05% POPOP and 20% 1-methylnaphthalene + 2% pTP + 0.05% POPOP + 0.02% K-27 revealed the maximum radiation resistance, about 7-9 Mrad.

Vasil'chenko, V. G.; Lapshin, V. G.; Peresypkin, A. I.; Konstantinchenko, A. A.; Pyshchev, A. I.; Shershukov, V. M.; Semenov, B. V.; Solov'ev, A. S.

1996-02-01

327

Analysis of GNSS receiver signal processing modification of scintillation parameters  

NASA Astrophysics Data System (ADS)

GNSS receivers have gained tremendous popularity in ionosphere and space weather monitoring. The output of GNSS receivers and resulting ionosphere scintillation indicators, however, are only convoluted scintillation signals and the receiver system function. This presentation will discuss different receiver signal processing algorithms impact on scintillation signal parameters. Scintillation signals from simulations and real data collected at high latitude and equatorial will be used to illustrate the receiver processing effects.

Morton, Y.

2013-12-01

328

Equatorial scintillation calculations based on coherent scatter radar and C/NOFS data  

NASA Astrophysics Data System (ADS)

During its transit through a region of equatorial ionospheric irregularities, sensors on board the Communication/Navigation Outage Forecasting System (C/NOFS) satellite provide a one-dimensional description of the medium, which can be extended to two dimensions if the structures are assumed to be elongated in the direction of the magnetic field lines. The C/NOFS scintillation calculation approach assumes that the medium is equivalent to a diffracting screen with random phase fluctuations that are proportional to the irregularities in the total electron content, specified through the product of the directly measured electron density by an estimated extent of the irregularity layer along the raypaths. Within the international collaborative effort anticipated by the C/NOFS Science Definition Team, the present work takes the vertical structure of the irregularities into more detailed consideration, which could lead to improved predictions of scintillation. Initially, it describes a flexible model for the power spectral density of the equatorial ionospheric irregularities, estimates its shape parameters from C/NOFS in situ data and uses the signal-to-noise ratio S/N measurements by the São Luís coherent scatter radar to estimate the mean square electron density fluctuation within the corresponding sampled volume. Next, it presents an algorithm for the wave propagation through a three-dimensional irregularity layer which considers the variations of along the propagation paths according to observations by the radar. Data corresponding to several range-time-intensity maps from the radar is used to predict time variations of the scintillation index S4 at the L1 Global Positioning System (GPS) frequency (1575.42 MHz). The results from the scintillation calculations are compared with corresponding measurements by the colocated São Luís GPS scintillation monitor for an assessment of the prediction capability of the present formulation.

Costa, Emanoel; de Paula, Eurico R.; Rezende, L. F. C.; Groves, Keith M.; Roddy, Patrick A.; Dao, Eugene V.; Kelley, Michael C.

2011-04-01

329

GEANT4 simulation of plastic scintillator strips with embedded optical fibers for a prototype of tomographic system  

NASA Astrophysics Data System (ADS)

The response to cosmic muons of plastic scintillator strips, with and without wavelength shifter fibers embedded, read out at both edges by photomultipliers has been studied through detailed GEANT4 simulations, with the aim of studying the light collection at the module ends under different conditions. The performed simulations, validated and tuned with data coming from a module prototype, could serve as an important guide for the design of a tomographic system based on cosmic ray muons.

Riggi, S.; La Rocca, P.; Leonora, E.; Lo Presti, D.; Pappalardo, G. S.; Riggi, F.; Russo, G. V.

2010-12-01

330

The evolution of scintillating medical detectors  

NASA Astrophysics Data System (ADS)

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

Hell, E.; Knüpfer, W.; Mattern, D.

2000-11-01

331

Statistics of time averaged atmospheric scintillation  

SciTech Connect

A formulation has been constructed to recover the statistics of the moving average of the scintillation Strehl from a discrete set of measurements. A program of airborne atmospheric propagation measurements was analyzed to find the correlation function of the relative intensity over displaced propagation paths. The variance in continuous moving averages of the relative intensity was then found in terms of the correlation functions. An empirical formulation of the variance of the continuous moving average of the scintillation Strehl has been constructed. The resulting characterization of the variance of the finite time averaged Strehl ratios is being used to assess the performance of an airborne laser system.

Stroud, P.

1994-02-01

332

Utilization of Optical Filters in a Scintillation Detector  

Microsoft Academic Search

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

Elihu Boldt; Costa Tsipis

1961-01-01

333

Study of a new boron loaded plastic scintillator  

Microsoft Academic Search

Neutron detection research using plastic scintillators has recently led to instrument development for several applications and particularly for nuclear material characterization. In particular, plastic scintillators exhibit a fast time response and a high efficiency for fast neutrons spectrometry. The use of boron loaded plastic scintillators has been also proposed in order to reduce dead time for fission neutron coincidence counting.

Stéphane Normand; Brigitte Mouanda; Serge Haan; Michel Louvel

2002-01-01

334

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

Microsoft Academic Search

An alpha scintillation survey instrument has been developed which is more rugged and efficient than conventional alpha scintillation detectors that use aluminized Mylar **** Mylar is a trademark of E.I. du Pont de Nemours & Co., Inc., Wilmington, DE, USA. radiation entrance windows. This new detector consists of a mixture of ZnS(Ag) phosphor and optically transparent epoxy. The scintillator mixture

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

1990-01-01

335

Nanocomposite scintillators for radiation detection and nuclear spectroscopy  

Microsoft Academic Search

A novel class of scintillating materials, which are nanocomposites of known scintillators, is described. These nanocomposite materials are expected to have improved properties with respect to the properties of the bulk scintillators from which they are derived. Improvements include enhanced light output, reduced cost and greater size scalability. Optical properties of the nanocomposite phosphor components are described, with emphasis on

Edward A. McKigney; Rico E. Del Sesto; Luiz G. Jacobsohn; Peter A. Santi; Ross E. Muenchausen; Kevin C. Ott; T. Mark McCleskey; Bryan L. Bennett; James F. Smith; D. Wayne Cooke

2007-01-01

336

optics: general-purpose scintillator light response simulation code  

Microsoft Academic Search

We present the program optics that simulates the light response of an ar- bitrarily 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 scintilla- tor lead to specific volume and temporal light

E. Frleÿz; B. K. Wright; D. Poÿcanic

337

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

NASA Astrophysics Data System (ADS)

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

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

1999-05-01

338

Cities Guide  

NSDL National Science Digital Library

From The Economist, their Cities Guide offers practical information ranging from accommodations to insider tips on getting around various US and world cities. A very nice touch are areas like the City Briefing section (top news stories, history pieces, and other tidbits) and the Being There area (subtopics include how to kill an hour and gifts to take home). City Guide also contains sections on cultural events, shopping, history, facts, and much more. [REB].

2001-01-01

339

Screening for cancer  

SciTech Connect

This book contains three sections: Fundamentals of Screening, Screening Tests, and Screening for Specific Cancer Sites. Each section consists of several chapters. Some of the chapter titles are: Principles of Screening and of the Evaluation of Screening Programs; Economic Aspects of Screening; Cervical Cytology; Screening Tests for Bladder Cancer; Fecal Occult Blood Testing; Screening for Cancer of the Cervix; Screening for Gastric Cancer; and Screening for Oral Cancer.

Miller, A.B.

1985-01-01

340

Mathematic model analysis of Gaussian beam propagation through an arbitrary thickness random phase screen.  

PubMed

In order to research the statistical properties of Gaussian beam propagation through an arbitrary thickness random phase screen for adaptive optics and laser communication application in the laboratory, we establish mathematic models of statistical quantities, which are based on the Rytov method and the thin phase screen model, involved in the propagation process. And the analytic results are developed for an arbitrary thickness phase screen based on the Kolmogorov power spectrum. The comparison between the arbitrary thickness phase screen and the thin phase screen shows that it is more suitable for our results to describe the generalized case, especially the scintillation index. PMID:21935188

Tian, Yuzhen; Guo, Jin; Wang, Rui; Wang, Tingfeng

2011-09-12

341

A Campaign Study of Ionospheric Scintillations Using Simultaneous Formosat-3\\/COSMIC Radio Occultation Observations and AFRL SCINDA Ground Scintillation Measurements  

Microsoft Academic Search

We report preliminary results from a campaign study of ionospheric scintillations using ionospheric radio occultation measurements by Formosat-3\\/COSMIC satellites and ground scintillation measurements by the Scintillation Network Decision Aid (SCINDA) network. Under the SCINDA project, scientists at the Air Force Research Laboratory (AFRL) have developed a sensor network for the purpose of monitoring low-latitude ionospheric total electron content (TEC) and

C. S. Lin; M. J. Starks; Y. Chu; S. Syndergarrd; K. M. Groves; S. Basu

2006-01-01

342

Development of scintillator plates with high energy resolution for alpha particles made of GPS scintillator grains  

NASA Astrophysics Data System (ADS)

A scintillator plate with high energy resolution was developed to produce an alpha particle monitor used in nuclear fuel reprocessing plants and mixed plutonium-uranium oxide (MOX) fuel plants. Grains of a Gd2Si2O7 (GPS) scintillator of several 10 to 550 ?m were fixed on a glass substrate and were then mechanically polished. By increasing the size of scintillator grains and removing fine powders, the collected light yield and energy resolution for alpha particles were drastically improved. Energy resolution of 9.3% was achieved using average grain size of 91 ?m. Furthermore, the ratios between counts in a peak and total counts were improved by more than 60% by the further increase of grain size and adoption of mechanically polished surfaces on both sides. Beta and gamma ray influences were suppressed sufficiently by the thin 100 ?m scintillator plates.

Shimaoka, Takehiro; Kaneko, Junichi H.; Izaki, Kenji; Tsubota, Youichi; Higuchi, Mikio; Nishiyama, Shusuke

2014-01-01

343

A High Throughput Scintillation Proximity Imaging Assay for Protein Methyltransferases  

PubMed Central

Protein methyltransferases (PMTs) orchestrate epigenetic modifications through post-translational methylation of various protein substrates including histones. Since dysregulation of this process is widely implicated in many cancers, it is of pertinent interest to screen inhibitors of PMTs, as they offer novel target-based opportunities to discover small molecules with potential chemotherapeutic use. We have thus developed an enzymatic screening strategy, which can be adapted to scintillation proximity imaging assay (SPIA) format, to identify these inhibitors. We took advantage of S-adenosyl-L-[3H-methyl]-methionine availability and monitored the enzymatically catalyzed [3H]-methyl addition on lysine residues of biotinylated peptide substrates. The radiolabeled peptides were subsequently captured by streptavidin coated SPA imaging PS beads. We applied this strategy to four PMTs: SET7/9, SET8, SETD2, and EuHMTase1, and optimized assay conditions to achieve Z? values ranging from 0.48 to 0.91. The robust performance of this SPIA for the four PMTs was validated in a pilot screen of approximately 7,000 compounds. We identified 80 cumulative hits across the four targets. NF279, a suramin analogue found to specifically inhibit SET7/9 and SETD2 with IC50 values of 1.9 and 1.1 ?M, respectively. Another identified compound, Merbromin, a topical antiseptic, was classified as a pan-active inhibitor of the four PMTs. These findings demonstrate that our proposed SPIA strategy is generic for multiple PMTs and can be successfully implemented to identify novel and specific inhibitors of PMTs. The specific PMT inhibitors may constitute a new class of anti-proliferative agents for potential therapeutic use.

Ibanez, Glorymar; Shum, David; Blum, Gil; Bhinder, Bhavneet; Radu, Constantin; Antczak, Christophe; Luo, Minkui; Djaballah, Hakim

2013-01-01

344

Hard X-ray polarimetry using scintillators  

Microsoft Academic Search

The linear polarization of the radiation from celestial sources can be investigated by studying the angular distribution of Compton scattered photons in a detection device. The authors present the design of a Compton polarimeter based on the technology of fiber-shaped scintillators. A total geometric area of 1000 cm2 or more could be obtained by repeating a basic polarimeter composed by

M. Feroci; M. N. Cinti; E. Costa; G. Matt; M. Rapisarda

1997-01-01

345

Testing of the scintillation sandwich prototype  

SciTech Connect

The 3 m{sup 2} prototype of the surface detector using optical fiber readout was completely prepared for testing measurements in February 1995 at Fermilab. Two 25 mm thick, 3 m{sup 2} acrylic scintillation plates (1.2 {times} 2.5 m{sup 2}) are used for light collection in the upper (above the 25 mm steel plate) and lower (below the steel) counters of the sandwich. The light is collected with the help of 1 mm diameter wavelength shifter fiber loops 3 m long inserted in the grooves on the top surface of the scintillator, 3 fibers per groove. We used Kurary Y11, 200 ppm of shifter dye, and double clad fibers. 1.5 m of clear fibers spliced to each end of the shifter fiber transport the light to the phototube. Spacing between the grooves is 5 cm. The counter`s edges were painted with BICRON (BC620) white reflective paint. The scintillation plates were wrapped with Dupont Tyvek. The glued bundle of fibers is connected to an EMI-9902KB 38 mm phototube through the simple light mixer bar. Used PM has a ``green extended`` rubidium bialkali photocathode. The report contains information on the testing of the scintillation sandwich.

Vashkevich, V. [Moscow State Univ. (Russian Federation). Inst. of Nuclear Physics

1995-06-01

346

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

347

LIQUID SCINTILLATION COUNTING WITH GLASS FIBER PAPER  

Microsoft Academic Search

The efficiency of counting C¹⁴ on cellulose paper was compared ; with that of glass fiber paper. It was observed that cellulose paper is only ; about 60% as efficient as glass fiber paper. Identical amounts of fucose-1-C\\/sup ; 14\\/ were placed on each type of paper and the disks were counted in a nonpolar ; scintillation fluid. The proportionality

K. G. Pinter; J. G. Hamilton; O. N. Miller

1963-01-01

348

A Ceramic Version of the LSO Scintillator  

Microsoft Academic Search

Although LSO is one of the most successful scintillator developments for medical diagnostics in the last two decades, good single crystals are not commercially available in any quantity. Consequently, we explored the feasibility of developing a ceramic version of the material, which requires a considerably lower temperature to consolidate the material to essentially crystalline density. Consolidation of the ceramic was

A. Lempicki; C. Brecher; H. Lingertat; S. R. Miller; J. Glodo; V. K. Sarin

2008-01-01

349

Experimental Study of Uranium Plastic Scintillator Calorimeters,  

National Technical Information Service (NTIS)

As preparation for the ZEUS high resolution calorimeter, sampling calorimeters made from 3.2 mm plates of depleted uranium read out by plastic scintillator of 3 mm and 5 mm thickness have been built. The response of hadrons, electrons and muons has been m...

G. d'Agostini A. Bamberger F. Barreiro E. Bernardi K. Dierks

1988-01-01

350

Two plastic scintillator measuring system HBG-2.  

National Technical Information Service (NTIS)

The beta-gamma measuring system HBG-2 is described. It consist of: 1. Two 40mm (Phi) x 3mm plastic scintillators, a beta-filter, a shielded cell, and a coincidence circuit; 2. Four counting channels in which one is reversible. A device is capable of measu...

T. M. Tran T. T. Nguyen

1992-01-01

351

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

352

Fast Scintillators for High Radiation Levels.  

National Technical Information Service (NTIS)

This article is a review of ongoing developmental work to make scintillators a viable and important element of the next generation of high energy physics detector systems. Although the key problem is that of radiation tolerance, attention has to be paid t...

S. Majewski C. Zorn

2000-01-01

353

An improved model of equatorial scintillation  

Microsoft Academic Search

One of the main limitations of the modeling work that went into the equatorial section of the Wideband ionospheric scintillation model (WBMOD) was that the data set used in the modeling was limited to two stations near the dip equator (Ancon, Peru, and Kwajalein Island, in the North Pacific Ocean) at two fixed local times (nominally 1000 and 2200). Over

J. A. Secan; R. M. Bussey; E. J. Fremouw; Sa. Basu

1995-01-01

354

ANALYSIS OF THREE-STATION INTERPLANETARY SCINTILLATION  

Microsoft Academic Search

Statistical models used in the analysis of drifting random patterns are discussed. A new method of estimating the drift velocity with minimal a priori assumptions is presented. It is shown that all the models which allow for pattern rearrangement, including the new method, can be highly sensitive to systematic errors. These techniques are applied to recent observations of interplanetary scintillation

J. W. Armstrong; W. A. Coles

1972-01-01

355

Temperature dependence of BCF plastic scintillation detectors  

PubMed Central

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

Wootton, Landon; Beddar, Sam

2013-01-01

356

Nonproportionality of Scintillator Detectors: Theory and Experiment  

Microsoft Academic Search

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

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

2009-01-01

357

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

358

Scintillation mechanism in stoichiometric cerium compounds.  

National Technical Information Service (NTIS)

These materials constitute a new class of scintillator media, with high speed and high light output. This is illustrated using CeF(sub 3), and CeP(sub 5)O(sub l4). While speed, being limited by a radiative lifetime of an allowed d-f transition on the Ce(s...

A. J. Wojtowicz A. Lempicki E. Berman

1992-01-01

359

Multistation VHF scintillation studies at low latitudes  

NASA Astrophysics Data System (ADS)

Amplitude scintillations data at 244 MHz (FLEETSAT, 73 E) recorded from a network of three stations at Waltair (177°N, 83.3°E), Nuzvid (16.8°N, 80.8°E) and Payyanur (12°N, 75.8°E) from August 1991 to April 1993 are used to study the characteristics of ionospheric irregularities at low and near-equatorial latitudes in the Indian sector. The occurrence and patch durations are found to be higher at the near-equatorial station Payyanur, when compared to the occurrence at the other two low latitude stations. Equinoctial maxima are seen at all three stations followed by secondary maxima in winter. However during summer, significant scintillations were present at Payyanur, while the occurrence is much reduced at the other two low latitude stations. Seintillations are also inhibited during magnetically disturbed days. The scintillation patches recorded at the two nearby low latitude stations (Waltair and Nuzvid) show similarities during post-sunset hours, while their characteristics are found to differ after midnight. From a comparison of similar patches simultaneously recorded at the above two nearby stations, the velocity components of the drift of ionospheric irregularities are found to show predominent eastward movements with velocities varying between 80 and 280 ms -1. The occurretice of daytime scintillations is found to be higher in summer months.

Rama Rao, P. V. S.; Sri Ram, P.; Jayachandran, P. T.; Prasad, D. S. V. V. D.

1996-10-01

360

Laptop Screens  

NSDL National Science Digital Library

This Physics 2000 page, from the University of Colorado, offers an introductory explanation of how the flat screens used in laptop computers work. The discussion included a discussion of polarization, twisted cells, the used of electrical field to control twisted cells, liquid crystal displays, and how we view colors.

Goldman, Martin

2011-01-03

361

Hearing Screening  

ERIC Educational Resources Information Center

Hearing levels are threatened by modern life--headsets for music, rock concerts, traffic noises, etc. It is crucial we know our hearing levels so that we can draw attention to potential problems. This exercise requires that students receive a hearing screening for their benefit as well as for making the connection of hearing to listening.

Johnson-Curiskis, Nanette

2012-01-01

362

Classroom Screening.  

ERIC Educational Resources Information Center

This classroom screening device was developed by the Circle Preschool First Chance Project, a government-funded program to integrate handicapped children into regular classroom activities, for use in preschools, nursery schools, Head Start centers and other agencies working with young children. It is designed to give a gross measure of a child's…

Alpha Plus Corp., Piedmont, CA.

363

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

Microsoft Academic Search

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

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

2010-01-01

364

Scintillation mechanism in stoichiometric cerium compounds  

SciTech Connect

These materials constitute a new class of scintillator media, with high speed and high light output. This is illustrated using CeF{sub 3}, and CeP{sub 5}O{sub l4}. While speed, being limited by a radiative lifetime of an allowed d-f transition on the Ce{sup +3} ion, cannot be improved (without loss of the light output), the light output in both cases falls significantly below the estimated theoretical limit. To explain this we propose a mechanism of scintillation process, in which transfer of excitation energy from the lattice to the d-f electronic structure of Ce{sup +3} ions is absent and the light output of the scintillator is limited to the excitation energy directly intercepted by Ce ions. The efficiency depends, therefore, on the competition for holes between Ce{sup +3} ions and anions, determining the share of the total energy deposited by a high energy particle, which can be transformed into scintillation photons. The mechanism requires that the Ce ion has a stable 4+ charge state. Ionization of Ce{sup +3} is followed by capturing of an electron and creation of the Ce bound exciton. In the next step the energy of the bound exciton is transferred to the d-f structure of the Ce ion and, in the final step, a scintillation photon is emitted. The relatively high light output characteristic of these materials is due to the high concentration of Ce ions. The reasons for the lack of efficient energy transfer from the lattice may reside in large relaxation energies of lattice excitations. We use this model to discuss potential improvements in the light output of CeF{sub 3}.

Wojtowicz, A.J.; Lempicki, A.; Berman, E. [Boston Univ., MA (United States). Dept. of Chemistry

1992-12-31

365

Eu-activated fluorochlorozirconate glass-ceramic scintillators  

SciTech Connect

Rare-earth-doped fluorochlorozirconate (FCZ) glass-ceramic materials have been developed as scintillators and their properties investigated as a function of dopant level. The paper presents the relative scintillation efficiency in comparison to single-crystal cadmium tungstate, the scintillation intensity as a function of x-ray intensity and x-ray energy, and the spatial resolution (modulation transfer function). Images obtained with the FCZ glass-ceramic scintillator and with cadmium tungstate are also presented. Comparison shows that the image quality obtained using the glass ceramic is close to that from cadmium tungstate. Therefore, the glass-ceramic scintillator could be used as an alternative material for image formation resulting from scintillation. Other inorganic scintillators such as single crystals or polycrystalline films have limitations in resolution or size, but the transparent glass-ceramic can be scaled to any shape or size with excellent resolution.

Johnson, J. A.; Schweizer, S.; Henke, B.; Chen, G.; Woodford, J.; Newman, P. J.; MacFarlane, D. R. [Energy Technology Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Energy Technology Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 and Department of Physics, Faculty of Science, University of Paderborn, Warburger Str. 100, D-33095 Paderborn (Germany); Department of Physics, Faculty of Science, University of Paderborn, Warburger Str. 100, D-33095 Paderborn (Germany); Energy Technology Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Australian Centre for Electromaterials Science and School of Chemistry, Monash University, Clayton, Victoria 3800 (Australia)

2006-08-01

366

Functional approach to lead tungstate (PWO) scintillators in development of their fabrication technology  

NASA Astrophysics Data System (ADS)

The problem of fabrication of lead tungstate (PWO) scintillation crystals with reproducible characteristics is approached by distinguishing two main functions of the scintillator: (i) conversion of the high-energy irradiation to light photons, and (ii) guiding of the light through the crystal to the detector. Optical transmittivity and, thus, the lightguiding capability of the crystal are mainly influenced by inclusions of W 1-yL yO 3-x. Variation of tungsten valency in the inclusions under irradiation or thermal treatment influences the transmittivity and, thus, the external light yield. The efficiency of radiation conversion into light is mainly governed by crystal structure. Radiative recombination in scheelite-type PbWO 4 results in emission in the blue region. The green luminescence component is shown to be caused by tungstenite-type regions, which occur in the surface layer under certain conditions of thermal treatment. The influence of the surface modification on the lightguiding properties of PWO scintillators is also discussed.

Burachas, S.; Beloglovsky, S.; Elizarov, D.; Makov, I.; Saveliev, Yu.; Vassilieva, N.; Ippolitov, M.; Manko, V.; Nikulin, S.; Nyanin, A.; Vasiliev, A.; Apanasenko, A.; Tamulaitis, G.

2005-01-01

367

Destination Guide  

NSDL National Science Digital Library

Summer is the traveling season, and this new site from National Geographic may well come in handy. The site offers informative briefs on a number of popular tourist destinations in the US and Canada, including national parks and major cities. These are selected via geographic pull-down menus or alphabetical/ state listings. Each guide offers an overview of the park or city, highlights, driving tours, bird-watching tips, nearby attractions, the best time to go, lodging and travel tips, and statistics, among other information. At present the Destination Guide covers about 30 spots, but more will be added on a continual basis.

368

Vision Screening  

NASA Technical Reports Server (NTRS)

The Visi Screen OSS-C, marketed by Vision Research Corporation, incorporates image processing technology originally developed by Marshall Space Flight Center. Its advantage in eye screening is speed. Because it requires no response from a subject, it can be used to detect eye problems in very young children. An electronic flash from a 35 millimeter camera sends light into a child's eyes, which is reflected back to the camera lens. The photorefractor then analyzes the retinal reflexes generated and produces an image of the child's eyes, which enables a trained observer to identify any defects. The device is used by pediatricians, day care centers and civic organizations that concentrate on children with special needs.

1993-01-01

369

Transparent screens.  

PubMed

There is a kind of transitional phenomenon found among certain borderline patients which is quite distinct from Winnicott's transitional object. These are patients who are preoccupied with maintaining proper physical distance from their objects, in order to regulate anxieties about isolation on the one hand, and identity-annihilating closeness on the other. Since they believe the activity of looking to be intrusive and devouring, hence dangerous, transparent screens are interposed between self and other, and serve as protective barriers. These screens function intrapsychically as well, to split off or hide those aspects of the self felt to be unacceptable. The analyst may witness the failure of the screen in several ways: it may create too great a distance, isolating the individual and keeping him from life; it may become contaminated by projections and turn into a persecutor, or trap the individual, a state of intolerable claustrophobia; most dramatically, it may suddenly shatter. The latter is associated with psychosis and death, and its appearance may be a harbinger of suicide. PMID:3403907

Rosenthal, R J

1988-01-01

370

Real-time Scintillation Monitoring in Alaska from a Longitudinal Chain of ASTRA's SM-211 GPS TEC and Scintillation Receivers  

NASA Astrophysics Data System (ADS)

Amplitude and phase scintillation can cause serious difficulties for GPS receivers. Intense scintillation can cause loss of lock. High latitude studies generally show that phase scintillation can be severe, but the amplitude scintillation tends to be small. The reason for this is not yet understood. Furthermore, the actual causes of the ionospheric irregularities that produce high latitude scintillation are not well understood. While the gradient drift instability is thought to be important in the F-region, there may be other structures present in either the E- or F-regions. The role of particle precipitation is also not well understood. Four of ASTRA's CASES GPS receivers were deployed in Alaska to demonstrate our ability to map scintillation in realtime, to provide space weather services to GPS users, and to initiate a detailed investigation of these effects. These dual-frequency GPS receivers measure total electron content (TEC) and scintillation. The scintillation monitors were deployed in a longitudinal chain at sites in Kaktovic, Fort Yukon, Poker Flat, and Gakona. Scintillation statistics show phase scintillations to be largest at Kaktovic and smallest at Gakona. We present GPS phase scintillation and auroral emission results from the Alaska chain to characterize the correspondence between scintillation and auroral features, and to investigate the role of high latitude auroral features in driving the phase scintillations. We will also present data showing how phase scintillation can cause other GPS receivers to lose lock. The data and results are particularly valuable because they illustrate some of the challenges of using GPS systems for positioning and navigation in an auroral region like Alaska. These challenges for snowplough drivers were recently highlighted, along with the CASES SM-211 space weather monitor, in a special video in which ASTRA and three other small businesses were presented with an entrepreneurial award from William Shatner (http://youtu.be/bIVKEQH_YPk).

Crowley, G.; Azeem, S. I.; Reynolds, A.; Santana, J.; Hampton, D. L.

2013-12-01

371

In situ irregularity identification and scintillation estimation using wavelets and CINDI on C/NOFS  

NASA Astrophysics Data System (ADS)

Wavelets are a time-domain method that is able to extract both time and frequency information from a signal. The Morlet wavelet is used here to characterize the magnitude of ionospheric irregularities using measurements of the total ion density from the Coupled Ion Neutral Dynamics Investigation package onboard the Communications/Navigation Outage Forecasting System spacecraft. The power in ionospheric irregularities at scale sizes less than 128 km is used to generate an irregularity amplitude index. This index is used with a phase screen analysis to form an estimate of scintillation at the satellite location. The temporal information retained in a wavelet analysis also allows for an accurate power spectrum calculation even when used on short segments of data which is useful for real-time processing of irregularity detection onboard a satellite or for analyzing the long data sets produced by a satellite. To validate the process, a comparison of the in situ scintillation estimate and Scintillation Network and Decision Aid measurements of the S4 index is presented.

Stoneback, R. A.; Heelis, R. A.; Caton, R. G.; Su, Y.-J.; Groves, K. M.

2013-07-01

372

Reflection Guides  

NSDL National Science Digital Library

This webpage provides links to professional development resources based on NCTM journal articles and other publications. Written by members of NCTM's Professional Development Services Committee, the Guides include implementation suggestions for professional development activities, discussion questions, extensions and links to other related publications. They cover a wide range of topics, both mathematical and pedagogical.

2012-01-01

373

Persuasion Guide.  

ERIC Educational Resources Information Center

In this teacher's guide to the textbook called "Persuasion" the emphasis is on assisting the teacher to develop in his students the skills of critical and creative thinking. Each instructional unit moves from the experience of persuasive techniques, through critical analysis, to the creative practice of the technique in question. Essays on…

1971

374

Monitoring and Forecasting Ionospheric Scintillation at High Latitudes (Invited)  

NASA Astrophysics Data System (ADS)

Ionospheric scintillation (rapid signal amplitude fading and phase fluctuation) poses a threat to reliable and safe operation of modern technology that relies on Global Navigation Satellite Systems (GNSS). Ionospheric scintillation of GNSS signal severely degrades positional accuracy, causes cycle slips leading to loss of lock that affects performance of radio communication and navigation systems. At high latitudes, the scintillation is caused by ionospheric irregularities produced through coupling between solar wind plasma and the magnetosphere. Climatology of GPS scintillation at high latitudes in both hemispheres shows that phase scintillation occurs predominantly on the dayside in the cusp and in the nightside auroral oval. Solar wind disturbances, in particular the co-rotating interaction regions (CIR) on the leading edge of high-speed streams (HSS) and interplanetary coronal mass ejections (ICME), have been closely correlated with the occurrence of scintillation at high latitudes. These results demonstrated a technique of probabilistic forecast of high-latitude phase scintillation occurrence relative to arrival times of HSS and ICME. The Canadian High Arctic Ionospheric Network (CHAIN) has been monitoring GPS ionospheric scintillation and total electron content (TEC) since November 2007. One-minute amplitude and phase scintillation indices from L1 GPS signals and TEC from L1 and L2 GPS signals are computed from amplitude and phase data sampled at 50 Hz. Since 2012, significant expansion of CHAIN has begun with installation of new receivers, each capable of tracking up to 30 satellites including GLONASS and Galileo. The receivers log the raw phase and amplitude of the signal up to a 100-Hz rate for scintillation measurements. We briefly review observations of ionospheric scintillation and highlight new results from CHAIN, including the climatology of scintillation occurrence, collocation with aurora and HF radar backscatter, correlation with CIRs and ICMEs, and the method of probabilistic forecasting of phase scintillation at high latitudes.

Prikryl, P.; Jayachandran, P. T.; Chadwick, R.; Kelly, T.

2013-12-01

375

Measurement accuracy and Cerenkov removal for high performance, high spatial resolution scintillation dosimetry  

SciTech Connect

With highly conformal radiation therapy techniques such as intensity-modulated radiation therapy, radiosurgery, and tomotherapy becoming more common in clinical practice, the use of these narrow beams requires a higher level of precision in quality assurance and dosimetry. Plastic scintillators with their water equivalence, energy independence, and dose rate linearity have been shown to possess excellent qualities that suit the most complex and demanding radiation therapy treatment plans. The primary disadvantage of plastic scintillators is the presence of Cerenkov radiation generated in the light guide, which results in an undesired stem effect. Several techniques have been proposed to minimize this effect. In this study, we compared three such techniques--background subtraction, simple filtering, and chromatic removal--in terms of reproducibility and dose accuracy as gauges of their ability to remove the Cerenkov stem effect from the dose signal. The dosimeter used in this study comprised a 6-mm{sup 3} plastic scintillating fiber probe, an optical fiber, and a color charge-coupled device camera. The whole system was shown to be linear and the total light collected by the camera was reproducible to within 0.31% for 5-s integration time. Background subtraction and chromatic removal were both found to be suitable for precise dose evaluation, with average absolute dose discrepancies of 0.52% and 0.67%, respectively, from ion chamber values. Background subtraction required two optical fibers, but chromatic removal used only one, thereby preventing possible measurement artifacts when a strong dose gradient was perpendicular to the optical fiber. Our findings showed that a plastic scintillation dosimeter could be made free of the effect of Cerenkov radiation.

Archambault, Louis; Beddar, A. Sam; Gingras, Luc [Departement de Radio-Oncologie et Centre de Recherche en Cancerologie, Hotel-Dieu de Quebec, 11 Cote du Palais, Quebec, QC G1R 2J6 (Canada)] (and others)

2006-01-15

376

Measurement accuracy and cerenkov removal for high performance, high spatial resolution scintillation dosimetry.  

PubMed

With highly conformal radiation therapy techniques such as intensity-modulated radiation therapy, radiosurgery, and tomotherapy becoming more common in clinical practice, the use of these narrow beams requires a higher level of precision in quality assurance and dosimetry. Plastic scintillators with their water equivalence, energy independence, and dose rate linearity have been shown to possess excellent qualities that suit the most complex and demanding radiation therapy treatment plans. The primary disadvantage of plastic scintillators is the presence of Cerenkov radiation generated in the light guide, which results in an undesired stem effect. Several techniques have been proposed to minimize this effect. In this study, we compared three such techniques-background subtraction, simple filtering, and chromatic removal-in terms of reproducibility and dose accuracy as gauges of their ability to remove the Cerenkov stem effect from the dose signal. The dosimeter used in this study comprised a 6-mm(3) plastic scintillating fiber probe, an optical fiber, and a color charge-coupled device camera. The whole system was shown to be linear and the total light collected by the camera was reproducible to within 0.31% for 5-s integration time. Background subtraction and chromatic removal were both found to be suitable for precise dose evaluation, with average absolute dose discrepancies of 0.52% and 0.67%, respectively, from ion chamber values. Background subtraction required two optical fibers, but chromatic removal used only one, thereby preventing possible measurement artifacts when a strong dose gradient was perpendicular to the optical fiber. Our findings showed that a plastic scintillation dosimeter could be made free of the effect of Cerenkov radiation. PMID:16485419

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

2006-01-01

377

Predicting the timing properties of phosphor-coated scintillators using Monte Carlo light transport simulation  

NASA Astrophysics Data System (ADS)

Current developments in positron emission tomography focus on improving timing performance for scanners with time-of-flight (TOF) capability, and incorporating depth-of-interaction (DOI) information. Recent studies have shown that incorporating DOI correction in TOF detectors can improve timing resolution, and that DOI also becomes more important in long axial field-of-view scanners. We have previously reported the development of DOI-encoding detectors using phosphor-coated scintillation crystals; here we study the timing properties of those crystals to assess the feasibility of providing some level of DOI information without significantly degrading the timing performance. We used Monte Carlo simulations to provide a detailed understanding of light transport in phosphor-coated crystals which cannot be fully characterized experimentally. Our simulations used a custom reflectance model based on 3D crystal surface measurements. Lutetium oxyorthosilicate crystals were simulated with a phosphor coating in contact with the scintillator surfaces and an external diffuse reflector (teflon). Light output, energy resolution, and pulse shape showed excellent agreement with experimental data obtained on 3 × 3 × 10 mm3 crystals coupled to a photomultiplier tube. Scintillator intrinsic timing resolution was simulated with head-on and side-on configurations, confirming the trends observed experimentally. These results indicate that the model may be used to predict timing properties in phosphor-coated crystals and guide the coating for optimal DOI resolution/timing performance trade-off for a given crystal geometry. Simulation data suggested that a time stamp generated from early photoelectrons minimizes degradation of the timing resolution, thus making this method potentially more useful for TOF-DOI detectors than our initial experiments suggested. Finally, this approach could easily be extended to the study of timing properties in other scintillation crystals, with a range of treatments and materials attached to the surface.

Roncali, Emilie; Schmall, Jeffrey P.; Viswanath, Varsha; Berg, Eric; Cherry, Simon R.

2014-04-01

378

Predicting the timing properties of phosphor-coated scintillators using Monte Carlo light transport simulation.  

PubMed

Current developments in positron emission tomography focus on improving timing performance for scanners with time-of-flight (TOF) capability, and incorporating depth-of-interaction (DOI) information. Recent studies have shown that incorporating DOI correction in TOF detectors can improve timing resolution, and that DOI also becomes more important in long axial field-of-view scanners. We have previously reported the development of DOI-encoding detectors using phosphor-coated scintillation crystals; here we study the timing properties of those crystals to assess the feasibility of providing some level of DOI information without significantly degrading the timing performance. We used Monte Carlo simulations to provide a detailed understanding of light transport in phosphor-coated crystals which cannot be fully characterized experimentally. Our simulations used a custom reflectance model based on 3D crystal surface measurements. Lutetium oxyorthosilicate crystals were simulated with a phosphor coating in contact with the scintillator surfaces and an external diffuse reflector (teflon). Light output, energy resolution, and pulse shape showed excellent agreement with experimental data obtained on 3 × 3 × 10 mm³ crystals coupled to a photomultiplier tube. Scintillator intrinsic timing resolution was simulated with head-on and side-on configurations, confirming the trends observed experimentally. These results indicate that the model may be used to predict timing properties in phosphor-coated crystals and guide the coating for optimal DOI resolution/timing performance trade-off for a given crystal geometry. Simulation data suggested that a time stamp generated from early photoelectrons minimizes degradation of the timing resolution, thus making this method potentially more useful for TOF-DOI detectors than our initial experiments suggested. Finally, this approach could easily be extended to the study of timing properties in other scintillation crystals, with a range of treatments and materials attached to the surface. PMID:24694727

Roncali, Emilie; Schmall, Jeffrey P; Viswanath, Varsha; Berg, Eric; Cherry, Simon R

2014-04-21

379

Quadruple screen test  

MedlinePLUS

... screen; Multiple marker screening; AFP plus; Triple screen test; AFP maternal; MSAFP; 4-marker screen ... This test is usually performed between the 15th and 22nd weeks of the pregnancy, but it is most accurate ...

380

Screening for Specific Phobias  

MedlinePLUS

... Treatment GAD vs. General Anxiety About the Economy Obsessive-Compulsive Disorder (OCD) Symptoms Treatment Hoarding: The Basics Staging an ... Screening for Generalized Anxiety Disorder (GAD) Screening for Obsessive-Compulsive Disorder (OCD) Screening for Panic Disorder Screening for Posttraumatic ...

381

Reflectance of polytetrafluoroethylene for xenon scintillation light  

SciTech Connect

Gaseous and liquid xenon particle detectors are being used in a number of applications including dark matter search and neutrino-less double beta decay experiments. Polytetrafluoroethylene (PTFE) is often used in these detectors both as electrical insulator and as a light reflector to improve the efficiency of detection of scintillation photons. However, xenon emits in the vacuum ultraviolet (VUV) wavelength region ({lambda}{approx_equal}175 nm) where the reflecting properties of PTFE are not sufficiently known. In this work, we report on measurements of PTFE reflectance, including its angular distribution, for the xenon scintillation light. Various samples of PTFE, manufactured by different processes (extruded, expanded, skived, and pressed) have been studied. The data were interpreted with a physical model comprising both specular and diffuse reflections. The reflectance obtained for these samples ranges from about 47% to 66% for VUV light. Other fluoropolymers, namely, ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), and perfluoro-alkoxyalkane (PFA) were also measured.

Silva, C.; Pinto da Cunha, J.; Pereira, A.; Chepel, V.; Lopes, M. I.; Solovov, V.; Neves, F. [Department of Physics, LIP-Coimbra, University of Coimbra, P-3004 516 Coimbra (Portugal)

2010-03-15

382

Internet access to data for scintillation compounds  

SciTech Connect

The LBL Pulsed X-Ray Facility has scintillation data on a large variety of inorganic scintillators. We offer this information on all compounds that we have tested. The only restrictions/favors that we ask users of this data are: (1) The data is intended for research use and may not be sold; (2) If any portion of the data is used in a publication, that the following text appear somewhere in the publication: {open_quotes}This work was supported in part by the Director, Office of Energy Research, Office of Health and Environmental Research, Medical Applications and Biophysical Research Division of the U.S. Department of Energy under contract No. DE-AC03-76SF00098, and in part by Public Health Service Grant No. R01 CA48002 awarded by the National Cancer Institutes, Department of Health and Human Services.{close_quotes}.

Moses, W.W.; West, A.C.; Derenzo, S.E. [and others

1995-09-01

383

Hybrid photodiodes in scintillation counter applications  

NASA Astrophysics Data System (ADS)

This paper describes the results obtained from various scintillators when viewed by a Hybrid PhotoDiode (HPD) with several different scintillation crystals. The energy loss spectra produced by gamma-ray photons having energies in the range of 20 to 662 keV were measured using a commercially available HPD. An excellent single photo-electron response was measured using a low-noise preamplifier. Measurements of the number of photo-electrons produced and the energy resolution of the full-energy peak as a function of the gamma-ray energy and the acceleration voltage were made. Finally, optical Monte Carlo simulations were used to estimate the light loss in the entrance window and to optimise its geometry. The potential advantage of incorporating a BGO entrance window for some applications was also explored.

Datema, C. P.; Pleasants, I. B.; Ramsden, D.

1997-02-01

384

Neutron detection with single crystal organic scintillators  

SciTech Connect

Detection of high-energy neutrons in the presence of gamma radiation background utilizes pulse-shape discrimination (PSD) phenomena in organics studied previously only with limited number of materials, mostly liquid scintillators and single crystal stilbene. The current paper presents the results obtained with broader varieties of luminescent organic single crystals. The studies involve experimental tools of crystal growth and material characterization in combination with the advanced computer modeling, with the final goal of better understanding the relevance between the nature of the organic materials and their PSD properties. Special consideration is given to the factors that may diminish or even completely obscure the PSD properties in scintillating crystals. Among such factors are molecular and crystallographic structures that determine exchange coupling and exciton mobility in organic materials and the impurity effect discussed on the examples of trans-stilbene, bibenzyl, 9,10-diphenylanthracene and diphenylacetylene.

Zaitseva, N; Newby, J; Hamel, S; Carman, L; Faust, M; Lordi, V; Cherepy, N; Stoeffl, W; Payne, S

2009-07-15

385

Transparent ceramic scintillator fabrication, properties, and applications  

NASA Astrophysics Data System (ADS)

Transparent ceramics offer an alternative to single crystals for scintillator applications such as gamma ray spectroscopy and radiography. We have developed a versatile, scaleable fabrication method, using Flame Spray Pyrolysis (FSP) to produce feedstock which is readily converted into phase-pure transparent ceramics. We measure integral light yields in excess of 80,000 Ph/MeV with Cerium-doped Garnets, and excellent optical quality. Avalanche photodiode readout of Garnets provides resolution near 6%. For radiography applications, Lutetium Oxide offers a high performance metric and is formable by ceramics processing. Scatter in transparent ceramics due to secondary phases is the principal limitation to optical quality, and afterglow issues that affect the scintillation performance are presently being addressed.

Cherepy, N. J.; Kuntz, J. D.; Roberts, J. J.; Hurst, T. A.; Drury, O. B.; Sanner, R. D.; Tillotson, T. M.; Payne, S. A.

2008-08-01

386

Reflectance of polytetrafluoroethylene for xenon scintillation light  

NASA Astrophysics Data System (ADS)

Gaseous and liquid xenon particle detectors are being used in a number of applications including dark matter search and neutrino-less double beta decay experiments. Polytetrafluoroethylene (PTFE) is often used in these detectors both as electrical insulator and as a light reflector to improve the efficiency of detection of scintillation photons. However, xenon emits in the vacuum ultraviolet (VUV) wavelength region (?~=175 nm) where the reflecting properties of PTFE are not sufficiently known. In this work, we report on measurements of PTFE reflectance, including its angular distribution, for the xenon scintillation light. Various samples of PTFE, manufactured by different processes (extruded, expanded, skived, and pressed) have been studied. The data were interpreted with a physical model comprising both specular and diffuse reflections. The reflectance obtained for these samples ranges from about 47% to 66% for VUV light. Other fluoropolymers, namely, ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), and perfluoro-alkoxyalkane (PFA) were also measured.

Silva, C.; Pinto da Cunha, J.; Pereira, A.; Chepel, V.; Lopes, M. I.; Solovov, V.; Neves, F.

2010-03-01

387

PAC studies with LSO scintillation crystals  

NASA Astrophysics Data System (ADS)

The LSO (lutetium oxyorthosilicate, Lu 2SiO 5) scintillation crystal has been shown to improve the efficiency of positron emission tomographs considerably due to its large average atomic number. This makes LSO also interesting for perturbed angular correlation since today's solid state studies require appropriate probes for specific purposes, like 77Br, 187W or 172Lu, with more complex energy spectra. We investigated the applicability of this new scintillator for perturbed angular correlation studies especially in experiments where the improvement of energy resolution as compared to BaF 2 is important without loosing time resolution. From these improvements we expect a larger effective anisotropy. Further, due to the high average atomic number of LSO its photopeak efficiency is considerably higher. We present here test measurements with 172Lu in thulium and a comparison with measurements on a BaF 2 setup.

Valentini, Riccardo; Vianden, Reiner

2010-11-01

388

A scintillator hodoscope at the Tevatron collider  

Microsoft Academic Search

A plastic scintillator hodoscope for an experiment at the Fermilab Tevatron proton-antiproton collider is described. The hodoscope is used on-line to form a charged multiplicity trigger and off-line to study charged particle multiplicity distributions. The hodoscope consists of 240 counters covering the pseudorapidity range of +\\/-3.25. It is designed to survive a radiation dose of up to 100 krad over

E. W. Anderson; C. S. Lindsey; C. H. Wang; C. Hojvat; D. Reeves; F. Turkot

1990-01-01

389

Effects of hadron irradiation on scintillating fibers  

Microsoft Academic Search

Trackers based on scintillating-fiber technology are being considered by the Solenoidal Detector Collaboration at SSC and the DO collaboration at Fermilab. Some 600 fibers in the Fermilab Tevatron CO area were irradiated, thereby obtaining a hadronic irradiation at realistic rates. Four-meter-long samples of ten Bicron polystyrene-based fibre types, maintained in air, dry nitrogen, argon, and vacuum atmospheres within stainless-steel tubes,

B. Abbott; D. Adams; T. Armstrong; M. Atac; A. Baumbaugh; B. Baumbaugh; M. Binkley; S. Bird; J. Bishop; N. Biswas; A. D. Bross; C. Buchanan; N. Cason; R. Chaney; D. Chrisman; M. Chung; D. Cline; G. Collins; M. Corcoran; D. Davis; R. Davies; J. Elias; H. Fenker; E. Fenyves; D. Finley; G. W. Foster; H. Goldberg; H. Hammack; A. Hasan; S. Heppelmann; J. Jaques; R. Jesik; J. Kauffman; R. Kehoe; C. Kelley; M. Keely; V. Kenney; R. Kephart; C. Kim; D. Koltick; J. Kolonko; J. Kubic; R. A. Lewis; J. Losecco; B. Lowery; J. Marchant; R. McIlwain; S. Margulies; H. Mendez; H. Miettenen; R. Moore; B. Oh; J. Orgeron; J. Passaneau; A. Pla-Dalmau; C. Rivetta; R. Ruchti; R. Scalise; J. Schmitz; W. Shephard; E. Shibata; J. Skeens; G. A. Smith; J. Solomon; J. Thomas; S. Tkaczyk; W. Toothacker; F. Vaca; D. Vandergriff; R. Wagner; J. Warchol; M. Wayne; J. Whitmore

1993-01-01

390

Microwave equatorial scintillation intensity during solar maximum  

Microsoft Academic Search

Scintillation levels at 1.5 GHz from the Appleton anomaly region of the magnetic equator and electrojet latitudes are compared, and show increased F-region irregularity intensity over the anomaly region during years with a high number of sunspots. Peak-to-peak fading greater than 27 dB is observed from Ascension Island, although only 7-9 dB is observed from Natal, Brazil, and Huancayo, Peru.

Jules Aarons; H. E. Whitney; Eileen MacKenzie; Santimay Basu

1981-01-01

391

Studies of NICADD Extruded Scintillator Strips  

SciTech Connect

About four hundred one meter long, 10 cm wide and 5 mm thick extruded scintillating strips were measured at four different points. The results of measurements strip responses to a radioactive source {sup 90}Sr are provided, and details of strip choice, preparation, and method of measurement are included. This work was essential for prototyping a tail catcher and muon tracker for a future international electron positron linear collider detector.

Dychkant, Alexandre; et al.

2005-03-01

392

Scintillating LXe\\/LKr electromagnetic calorimeter  

Microsoft Academic Search

A scintillating LXe\\/LKr electromagnetic calorimeter has been built at the ITEP and tested at the BATES (MIT) accelerator. The detector consists of a PMT matrix and 45 light collecting cells made of aluminized Mylar partially covered with p-terphenyl as a wavelength-shifter (WLS). Each pyramidal cell has (2.1×2.1)×40×(4.15×4.15) cm dimensions and is viewed by an FEU-85 glass-window photomultiplier. The detector has

D. Yu. Akimov; A. J. Bolozdynya; D. L. Churakov; V. N. Afonasyev; S. G. Belogurov; A. D. Brastilov; A. A. Burenkov; L. N. Gusev; V. F. Kuzichev; V. N. Lebedenko; T. A. Osipova; I. A. Rogovsky; A. Safronov; A. Simonychev; V. N. Solovov; V. S. Sopov; G. N. Smirnov; V. P. Tchernyshev; M. Chen; M. M. Smolin; W. Turchinetz; R. A. Minakova; V. M. Shershukov; V. H. Dodohov

1995-01-01

393

A scintillating optical fiber track imaging detector  

Microsoft Academic Search

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

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

1986-01-01

394

Position Sensitive Photomultiplier Tubes for Scintillation Imaging  

Microsoft Academic Search

The Position Sensitive Photomultiplier Tube (PMT) was developed mainly for scintillation imaging in the field of high energy physics and medical applications. This PMT consists of a proximity-type photocathode and 11 staged mesh dynodes. For performing two-dimensional detection, two sets of wire anodes arranged in perpendicular with each other performs a read-out of the secondary electrons emitted from the last

Hidehiro Kume; Shinichi Muramatsu; Masahiro Iida

1986-01-01

395

Current trends in scintillator detectors and materials  

Microsoft Academic Search

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

William W. Moses

2002-01-01

396

Large Volume Scintillation Chamber for Radon Counting  

Microsoft Academic Search

A 450-cc cylindrical Lucite chamber covered internally with ZnS(Ag) and viewed at each end by 5-in. photo-multiplier tubes with summed outputs has been used routinely as a low background (?0.8 counts per min for a new chamber) Rn scintillation counter. The counter is simple to construct and has operated reliably for about two years. The counting efficiency for Rn in

Hobart W. Kraner; Gerald L. Schroeder; Anthony R. Lewis; Robley D. Evans

1964-01-01

397

Improved Neutron Scintillators Based on Nanomaterials  

SciTech Connect

The development work conducted in this SBIR has so far not supported the premise that using nano-particles in LiFZnS:Ag foils improves their transparency to 420 (or other frequency) light. This conclusion is based solely on the light absorption properties of LiFZnS foils fabricated from nano- and from micro-particles. Furthermore, even for the case of the Gd{sub 2}O{sub 3} foils, the transmission of 420 nm light gained by using nano-particles all but disappears as the foil thickness is increased beyond about 0.2 mm, a practical scintillator thickness. This was not immediately apparent from the preliminary study since no foils thicker than about 0.04 mm were produced. Initially it was believed that the failure to see an improvement by using nano-particles for the LiFZnS foils was caused by the clumping of the particles in Toluene due to the polarity of the ZnS particles. However, we found, much to our surprise, that nano-particle ZnS alone in polystyrene, and in Epoxy, had worse light transmission properties than the micro-particle foils for equivalent thickness and density foils. The neutron detection measurements, while disappointing, are attributable to our inability to procure or fabricate Bulk Doped ZnS nanoparticles. The cause for the failure of nano-particles to improve the scintillation light, and hence improved neutron detection efficiency, is a fundamental one of light scattering within the scintillator. A consequence of PartTec's documentation of this is that several concepts for the fabrication of improved {sup 6}LiFZnS scintillators were formulated that will be the subject of a future SBIR submission.

Dennis Friesel, PhD

2008-06-30

398

Nanophosphor composite scintillators comprising a polymer matrix  

DOEpatents

An improved nanophosphor composite comprises surface modified nanophosphor particles in a solid matrix. The nanophosphor particle surface is modified with an organic ligand, or by covalently bonding a polymeric or polymeric precursor material. The surface modified nanophosphor particle is essentially charge neutral, thereby preventing agglomeration of the nanophosphor particles during formation of the composite material. The improved nanophosphor composite may be used in any conventional scintillator application, including in a radiation detector.

Muenchausen, Ross Edward (Los Alamos, NM); Mckigney, Edward Allen (Los Alamos, NM); Gilbertson, Robert David (Los Alamos, NM)

2010-11-16

399

Properties of the YAG:Ce scintillator  

Microsoft Academic Search

Light yield, light pulse shape due to gamma-rays and alpha-particles, energy resolution and time resolution of the new YAG:Ce scintillator were studied using a light readout by means of the XP2020Q photomultiplier and the S3590-03 photodiode. The light yield of 20 300 +\\/- 2000 photons\\/MeV was determined using three independent methods. The light pulse produced by gamma-rays consists of two

M. Moszynski; T. Ludziejewski; D. Wolski; W. Klamra; L. O. Norlin

1994-01-01

400

Thin GSO scintillator for neutron detection  

Microsoft Academic Search

The new scintillator cerium-doped gadolinium orthosilicate (GSO -- GdâSiOâ:Ce) has a light output that is about 20% that of NaI(T1). The enormous cross section of Gd for capture of.thermal neutrons makes GSO a candidate for novel types of neutron.detectors. The characteristic radiations from neutron capture in Gd can be stopped in about 75 μm of GSO. Data obtained from a

P REEDER

1994-01-01

401

Thin GSO scintillator for neutron detection  

Microsoft Academic Search

The new scintillator cerium-doped gadolinium orthosilicate (GSO - Gd2SiO5:Ce) has a light output that is about 20 percent that of NaI(Tl). The enormous cross section of Gd for capture of thermal neutrons makes GSO a candidate for novel types of neutron detectors. The characteristic radiations from neutron capture in Gd can be stopped in about 75 (mu)m of GSO. Data

P. L. Reeder

1994-01-01

402

Thin GSO scintillator for neutron detection  

Microsoft Academic Search

The new scintillator cerium-doped gadolinium orthosilicate (GSO-Gd2SiO5:Ce) has a light output that is about 20% that of NaI(Tl). The enormous cross section of Gd for capture of thermal neutrons makes GSO a candidate for novel types of neutron detectors. The characteristic radiations from neutron capture in Gd can be stopped in about 75 mum of GSO. Data obtained from a

P. L. Reeder

1994-01-01

403

Fast inorganic scintillators - status and outlook  

NASA Astrophysics Data System (ADS)

Scintillation detectors based on inorganic materials represent one of the most widely applied instrumentation techniques in the fields of nuclear and high-energy physics as well as medical or industrial applications. Driven by experimental requirements the research has focused onto a faster response, shorter decay times and higher compactness implementing high-Z ions. The discovery of the fast core-valence luminescence in BaF2, the allowed electric dipole transitions in Ce3+, and the short radiation lengths of BGO and PbWO4 have set important milestones. However, excellent time resolution is affected as well by the density of photoelectrons produced at the early stage of the signal generation and the integral light output. The paper will give a detailed overview of the present status on fast inorganic scintillators, their performance and the theoretical limitations on achievable energy and time resolutions. The results are illustrated by various applications in research. The state of the art scintillator material will be discussed based on new materials such as LaBr3 or LaCl3, which were doped with rare earth ions such as Ce3+-centers to reach decay times between 20 and 40ns, respectively.

Novotny, Rainer W.

2013-06-01

404

Boron-Loaded Silicone Rubber Scintillators  

SciTech Connect

Silicone rubber received attention as an alternative to polyvinyltoluene in applications in which the scintillator is exposed to high doses because of the increased resistance of the rubber to the formation of blue-absorbing color centers. Work by Bowen, et al., and Harmon, et al., demonstrated their properties under gamma/x-ray irradiation, and Bell, et al. have shown their response to thermal neutrons. This last work, however, provided an example of a silicone in which both the boron and the scintillator were contained in the rubber as solutes, a formulation which led to the precipitation of solids and sublimation of the boron component. In the present work we describe a scintillator in which the boron is chemically bonded to the siloxane and so avoids the problem of precipitation and loss of boron to sublimation. Material containing up to 18% boron, by weight, was prepared, mounted on photomultipliers, and exposed to both neutron and gamma fluxes. Pulse height spectra showing the neutron and photon response were obtained, and although the light output was found to be much poorer than from samples in which boron was dissolved, the higher boron concentrations enabled essentially 100% neutron absorption in only a few millimeters' thickness of rubber.

Bell, Z.W.; Maya, L.; Brown, G.M.; Sloop, F.V.Jr

2003-05-12

405

Scintillators with potential to supersede lanthanum bromide  

SciTech Connect

New scintillators for high-resolution gamma ray spectroscopy have been identified, grown and characterized. Our development efforts have focused on two classes of high light yield materials: Europium-doped alkaline earth halides and Cerium-doped garnets. Of the halide single crystals we have grown by the Bridgman method - SrI{sub 2}, CaI{sub 2}, SrBr{sub 2}, BaI{sub 2} and BaBr{sub 2} - SrI{sub 2} is the most promising. SrI{sub 2}(Eu) emits into the Eu{sup 2+} band, centered at 435 nm, with a decay time of 1.2 {micro}s and a light yield of up to 115,000 photons/MeV. It offers energy resolution better than 3% FWHM at 662 keV, and exhibits excellent light yield proportionality. Transparent ceramics fabrication allows production of Gadolinium- and Terbium-based garnets which are not growable by melt techniques due to phase instabilities. While scintillation light yields of Cerium-doped ceramic garnets are high, light yield non-proportionality and slow decay components appear to limit their prospects for high energy resolution. We are developing an understanding of the mechanisms underlying energy dependent scintillation light yield non-proportionality and how it affects energy resolution. We have also identified aspects of optical design that can be optimized to enhance energy resolution.

Cherepy, Nerine; Payne, Steven; Aszatlos, Steve; Hull, Giulia; Kuntz, J.; Niedermayr, Tom; Pimputkar, S.; Roberts, J.; Sanner, R.; Tillotson, T.; van Loef, Edger; Wilson, Cody; Shah, Kanai; Roy, U.; Hawrami, R.; Burger, Arnold; Boatner, Lynn; Choong, Woon-Seng; Moses, William

2009-06-01

406

Calorimetry using organic scintillators, 'a sideways perspective'.  

SciTech Connect

Over the last two decades, calorimetry baaed on organic scintillators has developed into an excellent technology for many experimental situations in high energy physics. The primary difficulty, that of extracting the light signals, has benefited from two milestone innovations. The first was the use of wavelength-shifting bars to allow light to be efficiently collected from large areas of scintillator and then readily piped to a readout device. The second of these was the extension of this approach to plastic wavelength-shifting optical fibers whose great flexibility and small diameter allowed a minimum of detector volume to be compromised by the read-out. These two innovations coupled with inventiveness have produced many varied and successful calorimeters. Equal response to both hadronic and electromagnetic showers can be realized in scintillator-based calorimeters. However, in general this is not the case and it is likely that in the search for greater performance, in the future, combined tracking and calorimeter systems will be required.

Proudfoot, J.

1999-09-10

407

Light collection from scintillation counters using WLS fibers and bars  

SciTech Connect

Several methods of collecting light on scintillation counters using WLS fibers and WLS bars were studied. Nearly 20 prototype counters with different designs and with sizes ranging from 14x11x1.3 cm{sup 3} to 105x60x1.3 cm{sup 3} have been tested using cosmic muons and radioactive source. The efficiency of light collection on number of photoelectrons, uniformity of response, and time resolution have been measured. Test results for two new designs of light collection from scintillator based on WLS fibers around perimeter of scintillator plate and WLS fibers placed in machined on scintillator plate deep grooves are presented. Two out of the studied designs have been chosen as the basic options for the Doe muon system upgrade: light collection using two WLS bars for the forward muon scintillation counters and light collection using WLS fibers in deep grooves on scintillator for central area muon counters.

Evdokimov, V. [Institute for High Energy Physics, Protvino, Russia 142284 (Russian Federation)

1998-11-09

408

Light collection from scintillation counters using WLS fibers and bars  

SciTech Connect

Several methods of collecting light on scintillation counters using WLS fibers and WLS bars were studied. Nearly 20 prototype counters with different designs and with sizes ranging from 14{times}11{times}1.3cm{sup 3} to 105{times}60{times}1.3cm{sup 3} have been tested using cosmic muons and radioactive source. The efficiency of light collection on number of photoelectrons, uniformity of response, and time resolution have been measured. Test results for two new designs of light collection from scintillator based on WLS fibers around perimeter of scintillator plate and WLS fibers placed in machined on scintillator plate deep grooves are presented. Two out of the studied designs have been chosen as the basic options for the D0 muon system upgrade: light collection using two WLS bars for the forward muon scintillation counters and light collection using WLS fibers in deep grooves on scintillator for central area muon counters.

Evdokimov, V.

1998-01-01

409

Methods for the continuous production of plastic scintillator materials  

SciTech Connect

Methods are disclosed for producing plastic scintillating material employing either two major steps (tumble-mix) or a single major step (inline-coloring or inline-doping). Using the two step method, the polymer pellets are mixed with silicone oil, and the mixture is then tumble mixed with the dopants necessary to yield the proper response from the scintillator material. The mixture is then placed in a compounder and compounded in an inert gas atmosphere. The resultant scintillator material is then extruded and pelletized or formed. When only a single step is employed, the polymer pellets and dopants are metered into an inline-coloring extruding system. The mixture is then processed under a inert gas atmosphere, usually argon or nitrogen, to form plastic scintillator material in the form of either scintillator pellets, for subsequent processing, or as material in the direct formation of the final scintillator shape or form.

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

1999-10-19

410

Methods for the continuous production of plastic scintillator materials  

DOEpatents

Methods for producing plastic scintillating material employing either two major steps (tumble-mix) or a single major step (inline-coloring or inline-doping). Using the two step method, the polymer pellets are mixed with silicone oil, and the mixture is then tumble mixed with the dopants necessary to yield the proper response from the scintillator material. The mixture is then placed in a compounder and compounded in an inert gas atmosphere. The resultant scintillator material is then extruded and pelletized or formed. When only a single step is employed, the polymer pellets and dopants are metered into an inline-coloring extruding system. The mixture is then processed under a inert gas atmosphere, usually argon or nitrogen, to form plastic scintillator material in the form of either scintillator pellets, for subsequent processing, or as material in the direct formation of the final scintillator shape or form.

Bross, Alan (Downers Grove, IL); Pla-Dalmau, Anna (Naperville, IL); Mellott, Kerry (Malta, IL)

1999-10-19

411

WLS R&D for the detection of noble gas scintillation at LBL: seeing the light from neutrinos, to dark matter, to double beta decay  

NASA Astrophysics Data System (ADS)

Radiation detectors with noble gasses as the active medium are becoming increasingly common in experimental programs searching for physics beyond the standard model. Nearly all of these experiments rely to some degree on collecting scintillation light from noble gasses. The VUV wavelengths associated with noble gas scintillation mean that most of these experiments use a fluorescent material to shift the direct scintillation light into the visible or near UV band. We present an overview of the R&D program at LBL related to noble gas detectors for neutrino physics, double beta decay, and dark matter. This program ranges from precise measurements of the fluorescence behavior of wavelength shifting films, to the prototyping of large are VUV sensitive light guides for multi-kiloton detectors.

Gehman, V. M.

2013-09-01

412

Light pulses to photomultiplier tubes from extended scintillators  

Microsoft Academic Search

Light pulses seen by photomultiplier tubes (PMTs) after propagation within long scintillator slats or rods, or large disc-shaped scintillators are investigated and compared with those from point-like scintillators. Results of experimental tests for the disc-shaped configuration, performed with the single photon counting technique, are presented and compared with numerical calculations. These calculations were performed describing the light pulse shape by

S. Albergo; D. Boemi; Z. Caccia; S. Costa; A. Insolia; S. Panebianco; R. Potenza; N. Randazzo; S. Reito; J. Romanski; G. V. Russo; C. Tuvé

1995-01-01

413

Seasonal modulation of GPS performance due to equatorial scintillation  

Microsoft Academic Search

Evening scintillation is an aspect of space weather occurring primarily in the equatorial region due to scattering of satellite signals by ionospheric F-region irregularities. In order to quantify scintillation-related performance degradation in GPS (Global Positioning System), we operated single frequency (L1) Ionospheric Scintillation Monitors (ISM), sampling at 50 Hz, at 6 sites in the South East Asia\\/Oceania region during the

R. M. Thomas; M. A. Cervera; A. Ghaffar Ramli; Effendy; P. Totarong; K. M. Groves; P. J. Wilkinson

2004-01-01

414

Scintillating glass for the detection of slow neutrons  

Microsoft Academic Search

A scintillating glass was prepared and investigated. The glass, with the composition Li2O. 2SiO2(Ce) may be used for the detection of slow neutrons. The scintillation efficiency of the glass relative to NaI(Tl) under electron excitement, was 1.4%. The ratio of the scintillation yields for electrons and a-particles was 3.8–4. The de-excitation time constant was ~0.15µ sec. The efficiency of glass

V. K. Voitovetskii; N. S. Tolmacheva; M. I. Arsaev

1960-01-01

415

Paraffin scintillator for radioassay of solid support samples.  

PubMed

A new paraffin scintillator used for solid support sample counting has been proposed, and its composition and various characteristics are described. The solid support sample treated with this scintillator can be easily handled because of rigid sample conditions. This technique provides great advantages such as the elimination of a large volume of scintillator and little radioactive waste material by using an economical polyethylene bag instead of the conventional counting vial. PMID:2551847

Fujii, H; Takiue, M

1989-01-01

416

Plastic scintillator investigations for relative dosimetry in proton-therapy  

Microsoft Academic Search

Plastic organic scintillators, polyvinyltoluene based, can be used with high sensitivity to detect 1–60 MeV proton beams. Thin scintillators can be applied to proton-therapy field as relative dosimeter thanks to their water-equivalent nature, high energy–light conversion efficiency, low dimensions and good proportionality to the absorbed dose at low stopping powers. Unfortunately, the quenching effect limits the use of the scintillators

L. Torrisi

2000-01-01

417

A plastic scintillation dosimeter for high dose rate brachytherapy  

Microsoft Academic Search

In vivo dose verification in brachytherapy requires a small insertable dosimeter with a real-time readout capability. Fibre optic scintillation dosimeters, consisting of a plastic scintillator coupled to an optical fibre, are one of the most promising dosimeters for this application. We have developed two sizes of the BrachyFOD™ scintillation dosimeter which have external diameters of 2.2 mm and 1 mm

J. Lambert; D. R. McKenzie; S. Law; J. Elsey; N. Suchowerska

2006-01-01

418

Rise time of BC422 plastic scintillator < 20 ps  

Microsoft Academic Search

The rise time of the plastic scintillator BC-422 has been determined to be less than 20 ps. To make the measurement, scintillator excitation was produced by X-ray pulses generated by focusing 20-ps, 2.5-TW laser pulses onto gold targets. Scintillator output was recorded with an optical streak camera whose response is 15 ps. This fast rise time identifies BC-422 as a

R. A. Lerche; D. W. Phillion

1991-01-01

419

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

Microsoft Academic Search

An alpha scintillation survey instrument has been developed which is more rugged and efficient than conventional alpha scintillation detectors that use aluminized Mylar{dagger} radiation entrance windows. This new detector consists of a mixture of ZnS(Ag) phosphor and optically transparent epoxy. The scintillator mixture is poured into a preformed mold to provide a thin layer of phosphor after the particles settle

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

1990-01-01

420

Equatorial scintillation of satellite signals and some drift characteristics of the scintillation  

NASA Astrophysics Data System (ADS)

VHF/UHF satellite signals from the Pacific FLEETSAT have been monitored in Guam from April 1982 through 1 May 1983 to study the drift characteristics of equatorial scintillation. Two receivers spaced 1500 feet (457 meters) apart in an east-west direction were used. In addition, one receiver was used to monitor the L-band signals from the Pacific MARISAT. Occurrence and intensity of equatorial scintillation are compared to drift velocities and geomagnetic and solar activity. Drift velocities and geomagnetic activity are also compared.

Paulson, M. R.

1983-10-01

421

Quick Guide to ERIC Tools for the Graduate Student.  

ERIC Educational Resources Information Center

This collection serves as a quick guide to Educational Resources Information Center (ERIC) tools graduate students may find useful. The guide contains example screens and information on each of these: (1) ACCESS ERIC Home Page, the hub of the ERIC system, which links to all Clearinghouses and support components; (2) the ERIC system slide show home…

ERIC Clearinghouse on Higher Education, Washington, DC.

422

Development of polystyrene-based scintillation materials and its mechanisms  

NASA Astrophysics Data System (ADS)

Scintillation materials based on polystyrene (PS) have been investigated. Para-terphenyl was employed as a fluorescent molecule (fluor) that functions as a wavelength shifter. A clear increase in photon yield of the scintillation materials relative to the pure PS was observed, which cannot be explained by the conventional theory of scintillation mechanism. Furthermore, the photon yield increased with flour concentration in accordance with a power-law. Here we reveal the emergence of a luminescence of PS-based scintillation materials and demonstrate that their photon yields can be controlled by the fluor concentration.

Nakamura, Hidehito; Kitamura, Hisashi; Shinji, Osamu; Saito, Katashi; Shirakawa, Yoshiyuki; Takahashi, Sentaro

2012-12-01

423

A ruggedized ZnS(Ag)/epoxy alpha scintillation detector  

SciTech Connect

An alpha scintillation survey instrument has been developed which is more rugged and efficient than conventional alpha scintillation detectors that use aluminized Mylar{dagger} radiation entrance windows. This new detector consists of a mixture of ZnS(Ag) phosphor and optically transparent epoxy. The scintillator mixture is poured into a preformed mold to provide a thin layer of phosphor after the particles settle to the clear epoxy surface. After partial curing, an optically transparent light pipe is coupled to the ZnS(Ag)/epoxy film by using an additional thin epoxy layer, forming a monolithic scintillator assembly. 2 refs., 3 figs., 2 tabs.

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

1990-01-01

424

Plasmonic light yield enhancement of a liquid scintillator  

SciTech Connect

We demonstrate modifications to the light yield properties of an organic liquid scintillator due to the localization of the tertiary fluorophore component to the surface of Ag-core silica-shell nanoparticles. We attribute this enhancement to the near-field interaction of Ag nanoparticle plasmons with these fluor molecules. The scintillation light yield enhancement is shown to be equal to the fluorescence enhancement within measurement uncertainties. With a suitable choice of plasmon energy and scintillation fluor, this effect may be used to engineer scintillators with enhanced light yields for radiation detection applications.

Bignell, Lindsey J.; Jackson, Timothy W. [Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234 (Australia)] [Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234 (Australia); Mume, Eskender [Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234 (Australia) [Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234 (Australia); Center of Excellence in Anti-matter Matter Studies, Research School of Physics and Engineering, The Australian National University, Canberra (Australia); Lee, George P. [Department of Materials Engineering, Monash University, Melbourne (Australia)] [Department of Materials Engineering, Monash University, Melbourne (Australia)

2013-05-27

425

Plasmonic light yield enhancement of a liquid scintillator  

NASA Astrophysics Data System (ADS)

We demonstrate modifications to the light yield properties of an organic liquid scintillator due to the localization of the tertiary fluorophore component to the surface of Ag-core silica-shell nanoparticles. We attribute this enhancement to the near-field interaction of Ag nanoparticle plasmons with these fluor molecules. The scintillation light yield enhancement is shown to be equal to the fluorescence enhancement within measurement uncertainties. With a suitable choice of plasmon energy and scintillation fluor, this effect may be used to engineer scintillators with enhanced light yields for radiation detection applications.

Bignell, Lindsey J.; Mume, Eskender; Jackson, Timothy W.; Lee, George P.

2013-05-01

426

Application of accelerators for the research and development of scintillators.  

PubMed

We introduce experimental systems which use accelerators to evaluate scintillation properties such as scintillation intensity, wavelength, and lifetime. A single crystal of good optical quality is often unavailable during early stages in the research and development (R&D) of new scintillator materials. Because of their beams' high excitation power and/or low penetration depth, accelerators facilitate estimation of the properties of early samples which may only be available as powders, thin films, and very small crystals. We constructed a scintillation spectrum measurement system that uses a Van de Graaff accelerator and an optical multichannel analyzer to estimate the relative scintillation intensity. In addition, we constructed a scintillation time profile measurement system that uses an electron linear accelerator and a femtosecond streak camera or a microchannel plate photomultiplier tube followed by a digital oscilloscope to determine the scintillation lifetimes. The time resolution is approximately 10 ps. The scintillation spectra or time profiles can be obtained in a significantly shorter acquisition time in comparison with that required by conventional measuring systems. The advantages of the systems described in this study can significantly promote the R&D of novel scintillator materials. PMID:17764319

Shibuya, Kengo; Koshimizu, Masanori; Asai, Keisuke; Muroya, Yusa; Katsumura, Yosuke; Inadama, Naoko; Yoshida, Eiji; Nishikido, Fumihiko; Yamaya, Taiga; Murayama, Hideo

2007-08-01

427

Note: Absolute calibration of two DRZ phosphor screens using ultrashort electron bunch  

SciTech Connect

This article gives the absolute calibration of two types phosphor screens (DRZ) that were used to detect and characterize electron bunches driven by laser-plasma accelerator. The test was performed with picoseconds electron bunch at a radio frequency linear electron accelerator in Tsinghua University. The photons emitted from DRZ screens showed good linear responses to the charge of incident electron bunch and cosine angular distribution in space. An energy conversional efficiency of effective scintillant matter was also calculated.

Wu, Y. C.; Zhu, B.; Dong, K. G.; Yan, Y. H.; Gu, Y. Q. [Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, CAEP, P.O.Box 919-986-6, Mianyang 621900 (China)

2012-02-15

428

Untersuchung der Lichtausbeute von Plastikszintillatoren. (Study on the response of plastic scintillators).  

National Technical Information Service (NTIS)

Minimally ionizing protons were used to study the response of curved and flat plastic scintillators of the 'Juelich Quirl', a scintillator hodoscope type developed by the IKP at Juelich. The response variation measured for the curved scintillator type was...

J. Thimmel

1993-01-01

429

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

National Technical Information Service (NTIS)

We describe the application of scintillating optical fiber in instrumentation for high energy particle physics. The basic physics of the scintillation process in polymers is discussed first and then we outline the fundamentals of scintillating fiber techn...

A. D. Bross

1991-01-01

430

Characterization of Ionospheric Scintillation Using Simultaneous Formosat-3\\/COSMIC Radio Occultation Observations and AFRL SCINDA Ground Scintillation Measurements  

Microsoft Academic Search

Ionospheric scintillation at low latitudes has been studied using ionospheric radio occultation (RO) measurements by the FORMOSAT-3\\/COSMIC micro-satellites in conjunction with ground-based data from the Scintillation Network Decision Aid (SCINDA) station at Kwajalein Atoll. The Air Force Research Laboratory has developed the SCINDA network for monitoring low-latitude ionospheric total electron content (TEC) and scintillation associated with equatorial spread F. The

M. J. Starks; C. S. Lin; K. M. Groves; T. R. Pedersen; S. Basu; S. Syndergaard; C. Rocken

2007-01-01

431

Florida's "Reading First" Assessment: Principal's Guide, 2005  

ERIC Educational Resources Information Center

Anyone who has worked as a teacher or principal in an elementary school understands the value of reliable and valid assessments of early reading progress. In order to implement an effective reading program, schools should have a coordinated plan for using screening, progress monitoring, diagnostics and outcome measures to guide instruction and to…

Howard, Patricia

2005-01-01

432

Forecasting low-latitude radio scintillation with 3-D ionospheric plume models: 2. Scintillation calculation  

Microsoft Academic Search

A three-dimensional model has been developed for the plasma plumes caused by interchange instabilities in the low-latitude ionosphere to describe the structure and extent of the radio scintillation generated by turbulence around and within the plumes. With the inclusion of the processes that determine the transport of plasma parallel to the geomagnetic field lines as well as transverse to them,

J. M. Retterer

2010-01-01

433

Computer automated data acquisition and control for measurement of scintillation materials and scintillating fibers  

SciTech Connect

Scintillation materials, and scintillating fibers are being developed for potential use as tracking detectors at the SSC (Superconducting Super Collider). These fibers will need high scintillation efficiency, short decay time constants, and good transmission characteristics. This paper discusses the combined use of the Apple Macintosh family of microcomputers and custom built and commercially available hardware and software used to aid in determining suitable materials production characteristics for long scintillating fibers or capillaries. This system includes the use of a Hitachi model F-2000 fluorescence spectrophotometer, LeCroy model 3001 qVt multichannel analyzer, LeCroy 8901A CAMAC to GPIB (general purpose interface bus) interface, LeCroy 4604 scaler, and a Centent CN0170 Micro-Stepping motor controller. The software for the system is written primarily in Microsoft QuickBASIC, and is discussed in detail. The potential use of a DigiKrom 240 monochromator for understanding attenuation as a function of wavelength and for reflection coefficient measurements is discussed.

Baumbaugh, B.W.; Bose, A.; Ditmire, T.; Kennedy, C.; Puseljic, D.; Ruchti, R.; Ryan, J. (Notre Dame Univ., IN (USA). Dept. of Physics); Baumbaugh, A.; Knickerbocker, K. (Fermi National Accelerator Lab., Batavia, IL (USA))

1990-04-01

434

Scintillating glass fiber neutron sensors: 2, Light transmission in scintillating fibers.  

National Technical Information Service (NTIS)

The capture and transmission of light from an event through a scintillating fiber is somewhat different than in conventional optical waveguide applications. A theoretical all-ray model that depends on surface and bulk loss factors is developed for this tr...

K. H. Abel R. J. Arthur M. Bliss

1993-01-01

435

Scintillating glass fiber neutron sensors: 3, Photon economy in scintillating fibers.  

National Technical Information Service (NTIS)

In an optical detector such as those constructed from scintillating glass fibers, the photons represent information. This study of the flow of information in a system of devices using PNL glass fibers was undertaken in order to resolve the conflict betwee...

K. H. Abel R. J. Arthur M. Bliss

1993-01-01

436

Equatorial Scintillation of Satellite Signals and some Drift Characteristics of the Scintillation.  

National Technical Information Service (NTIS)

Vhf/uhf satellite signals from the Pacific FleetSat have been monitored in Guam from April 1982 through 1 May 1983 to study the drift characteristics of equatorial scintillation. Two receivers spaced 1500 feet (457 metres) apart in an east-west direction ...

M. R. Paulson

1983-01-01

437

Lutetium aluminate: Spectroscopic and scintillation properties  

SciTech Connect

The present status of the LuAlO{sub 3}:Ce (LuAP) scintillator is reviewed and its performance compared to that of YAlO{sub 3}:Ce (YAP). The light output of LuAP, at this stage of development, appears to be limited by two factors: insufficient Ce concentration and the presence of a parasitic absorption. Both LuAP and YAP show a dependence of light output on thickness, indicating that YAP also suffers from parasitic absorption. Measurements on undoped material offer a clue to the identity of the parasite.

Lempicki, A.; Brecher, C. [Boston Univ., MA (United States). Dept. of Chemistry] [Boston Univ., MA (United States). Dept. of Chemistry; Wisniewski, D.; Wojtowicz, A.J. [Boston Univ., MA (United States). Dept. of Chemistry] [Boston Univ., MA (United States). Dept. of Chemistry; [N. Copernicus Univ., Torun (Poland). Inst. of Physics; Zych, E. [Boston Univ., MA (United States)] [Boston Univ., MA (United States); [Wroclaw Univ. (Poland). Dept. of Chemistry

1996-06-01

438

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

439

Terbium-activated heavy scintillating glasses  

Microsoft Academic Search

Tb-activated scintillating glasses with Ln2O3 (Ln=Y, Gd, Lu) concentrations up to 40mol% have been prepared. The effects of Ln3+ ions on the density, thermal properties, transmission, and luminescence properties under both UV and X-ray excitation have been investigated. Glasses containing Gd2O3 or Lu2O3 exhibit a density of more than 6.0g\\/cm3. Energy transfer from Gd3+ to Tb3+ takes place in Gd-containing

Jie Fu; Masaaki Kobayashi; John M. Parker

2008-01-01

440

Eu 3+-activated heavy scintillating glasses  

Microsoft Academic Search

Eu3+-activated scintillating glasses with molar compositions of 35SiO2–15B2O3–30Ln2O3–20AlF3 (Ln=Y, La, Gd, Lu) have been prepared. The effects of Ln3+ ions on the density, transmission, photoluminescence and radioluminescence have been studied. The glasses have high density, ranging from 4.0 to 6.1g\\/cm3 in the order of Y

J. Fu; M. Kobayashi; S. Sugimoto; J. M. Parker

2008-01-01

441

Neutron Detection using Lithium Glass Scintillator  

NASA Astrophysics Data System (ADS)

We have developed a neutron detector using a thin sheet of lithium-6 glass scintillator. Lithium-6 has a high capture cross-section for neutrons, giving high neutron detection efficiency. One of the difficulties of neutron detection is discriminating between neutron and gamma radiation. We have measured the gamma sensitivity of our detector to be one in 10,000. For nuclear non-proliferation applications, radioactive sources may be shielded. Unlike most neutron detectors, lithium glass detectors are more efficient at detecting neutrons if the source is shielded. We are testing different configurations to optimize the detector's neutron capture efficiency.

Wallace, Adam; Rees, Lawrence; Czirr, Bart

2011-10-01

442

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

443

Scintillators With Potential to Supersede Lanthanum Bromide  

Microsoft Academic Search

New scintillators for high-resolution gamma ray spectroscopy have been identified, grown and characterized. Our development efforts have focused on two classes of high-light-yield materials: europium-doped alkaline earth halides and cerium-doped garnets. Of the halide single crystals we have grown by the Bridgman method-SrI2, CaI2, SrBr2, BaI2 and BaBr2-SrI2 is the most promising. SrI2(Eu) emits into the Eu2+ band, centered at

Nerine J. Cherepy; Steve A. Payne; Stephen J. Asztalos; Giulia Hull; Joshua D. Kuntz; Thomas Niedermayr; Siddha Pimputkar; Jeffery J. Roberts; Robert D. Sanner; Thomas M. Tillotson; Edger van Loef; Cody M. Wilson; Kanai S. Shah; Utpal N. Roy; Rastgo Hawrami; Arnold Burger; Lynn A. Boatner; Woon-Seng Choong; William W. Moses

2009-01-01

444

Thin GSO scintillator for neutron detection  

NASA Astrophysics Data System (ADS)

The new scintillator cerium-doped gadolinium orthosilicate (GSO-Gd 2SiO 5:Ce) has a light output that is about 20% that of NaI(Tl). The enormous cross section of Gd for capture of thermal neutrons makes GSO a candidate for novel types of neutron detectors. The characteristic radiations from neutron capture in Gd can be stopped in about 75 ?m of GSO. Data obtained from a GSO detector that was about 0.6-mm thick demonstrated that thermal neutrons could easily be detected and that higher energy gamma rays caused minimal interference.

Reeder, P. L.

1994-12-01

445

Thin GSO scintillator for neutron detection  

NASA Astrophysics Data System (ADS)

The new scintillator cerium-doped gadolinium orthosilicate (GSO - Gd2SiO5:Ce) has a light output that is about 20 percent that of NaI(Tl). The enormous cross section of Gd for capture of thermal neutrons makes GSO a candidate for novel types of neutron detectors. The characteristic radiations from neutron capture in Gd can be stopped in about 75 (mu)m of GSO. Data obtained from a GSO detector that was about 0.6-mm thick demonstrated that thermal neutrons could easily be detected and that higher energy gamma rays caused minimal interference.

Reeder, P. L.

1994-05-01

446

Thin GSO scintillator for neutron detection  

SciTech Connect

The new scintillator cerium-doped gadolinium orthosilicate (GSO -- Gd{sub 2}SiO{sub 5}:Ce) has a light output that is about 20% that of NaI(T1). The enormous cross section of Gd for capture of.thermal neutrons makes GSO a candidate for novel types of neutron.detectors. The characteristic radiations from neutron capture in Gd can be stopped in about 75 {mu}m of GSO. Data obtained from a GSO detector that was about 0.6-mm thick demonstrated that thermal neutrons could easily be detected and that higher energy gamma rays caused minimal interference.

Reeder, P.L.

1994-05-01

447

Comparison of Luminescence ADP Production Assay and Radiometric Scintillation Proximity Assay for Cdc7 Kinase  

PubMed Central

Several assay technologies have been successfully adapted and used in HTS to screen for protein kinase inhibitors; however, emerging comparative analysis studies report very low hit overlap between the different technologies, which challenges the working assumption that hit identification is not dependent on the assay method of choice. To help address this issue, we performed two screens on the cancer target, Cdc7-Dbf4 heterodimeric protein kinase, using a direct assay detection method measuring [33P]-phosphate incorporation into the substrate and an indirect method measuring residual ADP production using luminescence. We conducted the two screens under similar conditions, where in one, we measured [33P]-phosphate incorporation using scintillation proximity assay (SPA), and in the other, we detected luminescence signal of the ATP-dependent luciferase after regenerating ATP from residual ADP (LUM). Surprisingly, little or no correlation were observed between the positives identified by the two methods; at a threshold of 30% inhibition, 25 positives were identified in the LUM screen whereas the SPA screen only identified two positives, Tannic acid and Gentian violet, with Tannic acid being common to both. We tested 20 out of the 25 positive compounds in secondary confirmatory study and confirmed 12 compounds including Tannic acid as Cdc7-Dbf4 kinase inhibitors. Gentian violet, which was only positive in the SPA screen, inhibited luminescence detection and categorized as a false positive. This report demonstrates the strong impact in detection format on the success of a screening campaign and the importance of carefully designed confirmatory assays to eliminate those compounds that target the detection part of the assay.

Takagi, Toshimitsu; Shum, David; Parisi, Monika; Santos, Ruth E.; Radu, Constantin; Calder, Paul; Rizvi, Zahra; Frattini, Mark G.; Djaballah, Hakim

2013-01-01

448

Designing and Implementing an Early Literacy Screening Protocol: Suggestions for the Speech-Language Pathologist.  

ERIC Educational Resources Information Center

This article provides a rationale for incorporating early literacy screening into speech language services for young children with communication impairments. Recommendations concern identifying which children and what areas of literacy should be targeted for screening. Guidelines for interpreting findings and for using screening to guide early…

Justice, Laura M.; Invernizzi, Marcia A.; Meier, Joanne D.

2002-01-01

449

The temporal structure of intensity scintillations near the magnetic equator  

Microsoft Academic Search

The temporal structure of weak and strong intensity scintillations observed with a geostationary satellite at 249 MHz near the magnetic equator is investigated. Results show that the power spectra for weak intensity scintillations exhibit an asymptote immediately beyond the Fresnel frequency, which denotes a power law variation of power spectral density with frequency yielding spectral indices ranging between -3 and

Santimay Basu; H. E. Whitney

1983-01-01

450

Pulse shape discrimination with new single crystal organic scintillators  

Microsoft Academic Search

Pulse shape discrimination in organic single crystal and liquid scintillators provides a means of identifying fission energy neutrons with high specificity. We present the results of a broad survey of over one hundred single crystal organic scintillators produced from low-temperature solution growth technique. Each crystal was evaluated for light yield and pulse shape discrimination performance. The pulse shape dependence on

Jason Newby; Natalia Zaitseva; Stephen Payne; Nerine Cherepy; Leslie Carman; Giulia Hull

2009-01-01

451

New Scintillating Glass for High Energy Physics Applications.  

National Technical Information Service (NTIS)

A new scintillating glass has been developed containing Cerium (3+) oxide in an aluminate host glass. In this material the scintillation emission spectrum is red-shifted relative to that observed for Ce sup 3+ in silicate glasses. Additionally emission an...

B. Baumbaugh D. Puseljic J. Bishop J. Busenitz N. Cason

1987-01-01

452

A new scintillating glass for high energy physics applications  

Microsoft Academic Search

A new scintillating glass has been developed containing Cerium (3+) oxide in an aluminate host glass. In this material the scintillation emission spectrum is red-shifted relative to that observed for Ce\\/sup 3+\\/ in silicate glasses. Additionally, emission and absorption spectra are more widely separated in the aluminate composition, suggesting that such glasses might have improved light transmission properties. The refractive

D. Puseljic; B. Baumbaugh; J. Bishop; J. Busenitz; N. Cason; J. Cunningham; R. Gardner; C. Kennedy; E. Mannel; R. Ruchti; W. Shephard; M. Zanabria; A. Baumbaugh; K. Knickerbocker; A. Rogers; B. Kinchen; C. G. A. Hill

1988-01-01

453

Development of Gd2O3 based dense scintillating glass  

Microsoft Academic Search

Combined electromagnetic and hadron calorimeter based on a total absorption principle using scintillating crystals has been proposed recently for the future ILC. Advances in low level photon counting technology, including the silicon photo-multipliers, make such kind of calorimeters possible. Searching for a suitable calorimeter media that is dense and inexpensive is critical-Scintillating glass is an attractive option for the total

Yunlong Zhang; Xiaolian Wang; Zizong Xu; Yuepin Zhang; Haiping Xia; Yifang Wang; Tianchi Zhao

2009-01-01

454

Laser and Electric Arc Synthesis of Nanocrystalline Scintillators  

Microsoft Academic Search

Two new methods of preparation of nanocrystalline scintillators are described. Laser ablation of microscopic powders immersed in optically transparent liquid was used to produce spherical nanoparticles, which preserved the initial compositions. Electric arc discharge between electrodes of definite metals immersed in water solutions of different salts produces a vast variety of scintillating compounds with nanoscopic dimensions and morphologies having crystallographic

Nikolay V. Klassen; Oksana A. Krivko; Victor V. Kedrov; Semen Z. Shmurak; Aleksander P. Kiselev; Ivan M. Shmyt'ko; Elena A. Kudrenko; Aleksander A. Shekhtman; Anatoliy V. Bazhenov; Tatiana N. Fursova; Vladimir O. Abramov; Nikolay A. Bulychev; Eduard V. Kisterev

2010-01-01

455

Surface preparation and coupling in plastic scintillator dosimetry  

Microsoft Academic Search

One way to improve the performance of scintillation dosimeters is to increase the light-collection efficiency at the coupling interfaces of the detector system. We performed a detailed study of surface preparation of scintillating fibers and their coupling with clear optical fibers to minimize light loss and increase the amount of light collected. We analyzed fiber-surface polishing with aluminum oxide sheets,

Guylaine Ayotte; Louis Archambault; Luc Gingras; Fre?de?ric Lacroix; A. Sam Beddar; Luc Beaulieu

2006-01-01

456

Large Plastic Scintillation Detectors for the Nuclear Materials Identification System  

Microsoft Academic Search

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

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

2004-01-01

457

Discrimination of naturally occurring radioactive material in plastic scintillator material  

Microsoft Academic Search

Plastic scintillator material is used in many applications for the detection of gamma rays from radioactive material, primarily due to the sensitivity per unit cost compared to other detection materials. However, the resolution and lack of full-energy peaks in the plastic scintillator material prohibits detailed spectroscopy. Therefore, other materials such as doped sodium iodide are used for spectroscopic applications. The

J. H. Ely; R. T. Kouzes; B. D. Geelhood; J. E. Schweppe; R. A. Warner

2004-01-01

458

Photomultiplier Tubes for BaF2\\/BGO Crystal Scintillators  

Microsoft Academic Search

BGO\\/BaFâ crystals have been widely employed as scintillation detectors for radioactive sources and charged particles. Photomultiplier Tubes (PMT) are conventionally used on the detector with these scintillators. For these applications, the PMT with rectangular and dual photocathode (to be coupled with BGO crystal) was developed in order to reduce the dead space among PMTs in assembling them together as a

Hidehiro Kune; Takashi Watanabe; Masahiro Iida; Teruhiko Matsushita; Seiji Suzuki

1986-01-01

459

Purification of KamLAND-Zen liquid scintillator  

SciTech Connect

KamLAND-Zen is neutrino-less double-beta decay search experiment using enriched 300 kg of {sup 136}Xe dissolved in pure liquid scintillator. This report is purification work of liquid scintillator for KamLAND-Zen experiment before installation in the inner-balloon and background rejection processes after installation.

Ikeda, Haruo [Research Center for Neutrino Science, Tohoku University, Sendai 980-8578 (Japan)] [Research Center for Neutrino Science, Tohoku University, Sendai 980-8578 (Japan)

2013-08-08

460

Cerium doped silica scintillating fiber sensor for ? radiation measurement  

NASA Astrophysics Data System (ADS)

Remote optical fiber sensors for radiation measurement are very useful in high radiation fields. In this paper, we fabricated scintillating optical fiber by using a cerium-doped silica rod. In the drawing process, we obtained different fiber samples by changing the drawing temperature and speed. The drawing temperature is from 1900 to 2200 °C and the speed is from 1 to 10 m/min. The experimental results showed that the optical rod physical properties such as viscosity, tension and scintillating efficiency can be controlled by the parameters of temperature and speed. The optical properties and chemical composition of the scintillating optical fiber have been analyzed by Raman spectra and X-ray fluorescence spectrometer (XRF-1800, SHIMADZU). The concentration of the doped cerium is 0.55%. Moreover, a test system is proposed to measure the scintillating performa