Note: This page contains sample records for the topic scintillating guides screen from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

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

2

Laser cutting of plastic scintillator and light guide materials  

Microsoft Academic Search

Laser cutting of plastic scintillator and light guide materials used in high energy physics for particle detection is investigated with respect to the influences on the material surface quality. It has been found that the optical reflection factor R is a reliable measure for evaluating the quality of a cut surface. The cut light guide materials based on pure PMMA

Jürgen Bähr; Hartmut Bärwolff; Adolf-Ernst Schwind; Martin Thiele; Günther Wiedemann

1989-01-01

3

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

4

Absolute charge calibration of scintillating screens for relativistic electron detection  

SciTech Connect

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/mm{sup 2}. The screens showed a linear photon-to-charge dependency over several orders of magnitude. An onset of saturation effects starting around 10-100 pC/mm{sup 2} 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.; Popp, A.; Schmid, K.; Karsch, S.; Krausz, F. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Ludwig-Maximilians-Universitaet Muenchen, Am Coulombwall 1, D-85748 Garching (Germany); Zeil, K.; Jochmann, A.; Kraft, S. D.; Sauerbrey, R.; Cowan, T.; Schramm, U. [Forschungszentrum Dresden Rossendorf, Bautzner Landstrasse 400, D-01328 Dresden (Germany); Hidding, B.; Kudyakov, T. [Institut fuer Laser und Plasmaphysik, Heinrich-Heine-Universitaet Duesseldorf, Universitaetsstrasse 1, D-40225 Duesseldorf (Germany); Sears, C. M. S.; Veisz, L. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Pawelke, J. [Forschungszentrum Dresden Rossendorf, Bautzner Landstrasse 400, D-01328 Dresden (Germany); Oncoray, Technische Universitaet Dresden, Fetscher Strasse 74, D-01307 Dresden (Germany)

2010-03-15

5

New scintillators discovered by high-throughput screening  

NASA Astrophysics Data System (ADS)

We report the scintillation luminosities, decay times, and emission wavelengths for 19 Ce3+ activated scintillators, 18 Eu2+ activated scintillators, and 4 self-activated scintillators. Of these, 18 have not been previously reported either as phosphors or scintillators. Their luminosities range from 40,000 to under 1000 photons/MeV. While these scintillators may not have properties that make them top candidates for widespread use, their data will contribute to a deeper understanding of factors that limit scintillator performance.

Derenzo, Stephen; Bizarri, Gregory; Borade, Ramesh; Bourret-Courchesne, Edith; Boutchko, Rostyslav; Canning, Andrew; Chaudhry, Anurag; Eagleman, Yetta; Gundiah, Gautam; Hanrahan, Stephen; Janecek, Martin; Weber, Marvin

2011-10-01

6

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

2008-05-19

7

Screening Method of Inorganic Scintillators for Photon Counting  

NASA Astrophysics Data System (ADS)

Inorganic scintillators play an important role in detection and visualization of ionizing radiation. A scintillator with both high light yield and fast response has yet to be found. These methods are useful in detector applications for homeland security and nuclear non-proliferation. New scintillators are necessary to improve radiation detectors for detection of fissile materials specifically when shielded. At ORNL, several new inorganic scintillators including various versions of ZnO, and SnO2 are being evaluated to determine light yield and decay times. Crystals are grown here, doped or painted with metals such as Al, Cd, Sn or Ga and measured. The photons emitted from a scintillator from a single incident alpha or neutron can be counted and graphed, allowing the luminosity and decay constants to be determined

Pritchard, M.

2004-10-01

8

Screening Method of New Inorganic Scintillators for Photon Counting  

NASA Astrophysics Data System (ADS)

Inorganic scintillators play an important role in detection and visualization of ionizing radiation. A scintillator with both high light yield and fast response has yet to be found. These methods are useful in detector applications for homeland security and nuclear non-proliferation. New scintillators are necessary to improve radiation detectors for detection of fissile materials specifically when shielded. At ORNL, several new inorganic scintillators including various versions of ZnO, and SnO2 are being evaluated to determine light yield and decay times. Crystals are grown here, doped or painted with metals such as Al, Cd, Sn or Ga and measured. The photons emitted from a scintillator from a single incident alpha or neutron can be counted and graphed, allowing the luminosity and decay constants to be determined. The promising samples are also being evaluated for exact luminosity through spectroscopy.

Pritchard, Megan

2004-10-01

9

Optimization of Screening for Radioactivity in Urine by Liquid Scintillation.  

National Technical Information Service (NTIS)

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 qu...

R. P. Reese R. T. Preston S. T. Shanks

2007-01-01

10

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

11

Estimation of aperture averaged scintillations in weak turbulence regime for annular, sinusoidal and hyperbolic Gaussian beams using random phase screen  

NASA Astrophysics Data System (ADS)

Using the random phase screen method, aperture averaged scintillations for annular, sinusoidal and hyperbolic Gaussian beams are estimated. Prior to this estimation, the designed random phase screen setup is tested against the known results of the existing literature from the aspects of receiver intensity distribution, point-like scintillation index and aperture averaged scintillation of spherical and Gaussian beam waves. Having obtained satisfactory results, we then proceed to estimate aperture averaged scintillations for annular, sinusoidal and hyperbolic Gaussian beams. Our findings indicate that at a fixed aperture radius of 5 cm, sine Gaussian beam exhibits the highest scintillation, annular Gaussian beam has on the other hand has the lowest scintillations. When examined against varying aperture sizes, the scintillation ordering of beams does not change. Furthermore, although larger aperture sizes achieve substantial scintillation reductions, the rate of reductions gradually become smaller.

Eyyubo?lu, Halil T.

2013-11-01

12

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

13

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

14

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 survey of the problem for the

C. Zorn

1993-01-01

15

Multiple phase screen modeling of ionospheric scintillation along radio occultation raypaths  

NASA Astrophysics Data System (ADS)

We present the Radio Occultation Scintillation Simulator (ROSS), which uses the multiple phase screen method (MPS) to simulate the forward scatter of radio waves by irregularities in the equatorial ionosphere during radio occultation experiments. ROSS simulates propagation through equatorial plasma bubbles which are modeled as homogeneous electron density fluctuations modulated by a Chapman profile in altitude and a Gaussian window in the magnetic east-west direction. We adjust the parameters of the density model using electron density profiles derived from the ALTAIR incoherent scatter radar (9.4°N, 167.5°E, 4.3° north dip), and space-to-ground observations of scintillation using VHF and GPS receivers that are colocated with the radar. We compare the simulated occultation scintillation to observations of scintillation from the CORISS instrument onboard the C/NOFS satellite during a radio occultation occurring near ALTAIR on 21 April 2009. The ratio of MPS predicted S4 to CORISS observed S4 throughout the F region altitudes of 240-350 km ranged between 0.86 and 1.14.

Carrano, Charles S.; Groves, Keith M.; Caton, Ronald G.; Rino, Charles L.; Straus, Paul R.

2011-12-01

16

The effect of phase scintillations on the accuracy of phase screen simulation using deterministic screens derived from GPS and ALTAIR measurements  

NASA Astrophysics Data System (ADS)

Radio receivers capable of high-rate sampling such as GPS scintillation monitors and the ALTAIR VHF/UHF tracking radar can measure ionospheric phase fluctuations suitable for scintillation modeling using phase screen techniques. For modeling purposes, the phase variations caused by the refractive effects of electron density irregularities encountered along the propagation path are desired. The phase fluctuations measured by ground-based receivers, however, also include the unwanted effects of diffraction (phase scintillations). In this paper, we investigate the effect of phase scintillations on the accuracy of phase screen simulation when using the phase measured on the ground as a proxy for the ionospheric screen. Using stochastic and deterministic (measured) phase screens, we quantitatively assess the accuracy of this approach by cross-correlating the predicted and measured intensity fluctuations. We find that the intensity cross-correlation is less than unity even in the weak scatter limit, due to the presence of weak phase scintillations. This correlation decreases rapidly with increasing irregularity strength once rapid transitions in the phase (strong phase scintillations) develop. We demonstrate that, when using the measured phase on the ground as a proxy for the ionospheric screen, both the temporal structure of simulated fluctuations and their statistics deviate increasingly from those of the measurements as the turbulence strength increases, especially when strong phase scintillations are present. We also demonstrate that back-propagating the complex signal up to ionospheric altitudes prior to the forward propagation calculation yields improved results, but some errors still remain as a consequence of neglecting amplitude fluctuations which develop inside the random medium.

Carrano, Charles S.; Groves, Keith M.; Caton, Ronald G.

2012-08-01

17

Automated High Throughput Screening for Serine Kinase Inhibitors Using a LEADSeeker™ Scintillation Proximity Assay in the 1536Well Format  

Microsoft Academic Search

High-throughput screening in the 1536-well format has been largely restricted to solution-based and cell-based screens. In this article, we show the feasibility of a completely automated, robust scintillation proximity assay in the 1536-well format that is suitable to identify inhibitors for a serine\\/threonine kinase from a compound library. The introduction of [33P]phosphate into a biotinylated peptide substrate mirrors the activity

Gabriele Sorg; Hans-Dieter Schubert; Frank H. Büttner; Ralf Heilker

2002-01-01

18

New process for screen cutting: water-jet guided laser  

Microsoft Academic Search

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

Delphine Perrottet; Simone Amorosi; Bernold Richerzhagen

2005-01-01

19

Synthesis and Screening of Thin Films in the CeCl3-CeBr3 System for Scintillator Applications  

SciTech Connect

Thin film samples of CeCl3, CeBr3, and combinatorial compositions along the CeCl3-CeBr3 join were produced using thermal evaporation, which is being evaluated as a method for rapid screening of new scintillator materials. The combinatorial thin films were shown to be compositionally reproducible from run-to-run within reasonable limitations. Analytical results suggest a continuous variation in the combinatorial samples in terms of their compositions, crystal structures, and luminescence characteristics.

Matson, Dean W.; Graff, Gordon L.; Male, Jonathan L.; Johnson, Bradley R.; Nie, Zimin; Joly, Alan G.; Olsen, Larry C.

2010-04-02

20

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.

21

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

22

Developmental Screening in Early Childhood: A Guide (5th Edition)  

ERIC Educational Resources Information Center

|This edition covers the basics of screening used to identify which children may have learning problems or disabilities. It offers advice for selecting an appropriate screening instrument and for setting up a screening program. The book contains reviews of current developmental screens, plus an entirely new annotated bibliography. For the first…

Atkins-Burnett, Sally; Meisels, Samuel

2005-01-01

23

Simulation Study of the Role Played by Intensifying or Support Layers in Scintillation Screens  

Microsoft Academic Search

The advantage of using reinforcing substrate layers with phosphor screens is that they increase the phosphor sensitivity and filter the scattered radiation, while providing a mechanical support for the phosphor layer. A simulation model based on the Monte Carlo code Geant4 was developed to study the influence of the substrate properties (material, thickness) on the phosphor screen spatial response. The

S. A. Pistrui-Maximean; N. Freud; J. M. Letang; A. H. Walenta; A. Koch; G. Montarou; D. Babot

2007-01-01

24

Pick up screens for x-ray image intensifier tubes employing evaporated activated scintillator layer  

Microsoft Academic Search

The present invention relates in general to methods for making pick-up screens for x-ray image intensifier tubes and, more particularly, to an improved method wherein the x-ray fluorescent phosphor screen element is formed by evaporation of an alkali metal halide material in vacuum and condensing the evaporated material on an x-ray transparent portion of the x-ray intensifier tube, whereby a

Spicer

1976-01-01

25

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

26

A power law phase screen model for ionospheric scintillation 2. Strong scatter  

Microsoft Academic Search

In this paper the results for the second-order statistics of intensity are extended to accommodate strong scattering. The analysis is based on the formulation of the Gaussian phase screen model developed by Gochelashvily and $hishov [1971], who showed that the intensity spectral density function (SDF) is given by the formula

C. L. Rino

1979-01-01

27

Federal Remediation Technologies Screening Matrix and Reference Guide. Third Edition.  

National Technical Information Service (NTIS)

The purpose of this document is to provide enough information to allow the reader to use the guide, in combination with other references, to efficiently proceed from identifying a contaminated site toward communicating and recommending suitable site remed...

J. Ledbetter J. Van Deuren Z. Wang

1997-01-01

28

RADC (Rome Air Development Center) Guide to Environmental Stress Screening.  

National Technical Information Service (NTIS)

This in-house report (guidebook)provides guidelines and techniques for conducting Environmental Stress Screening (ESS) programs during development and production. ESS is a process whereby environmental stimulii are applied to electronic equipment in order...

E. Fiorentino

1986-01-01

29

A computational screen for methylation guide snoRNAs in yeast.  

PubMed

Small nucleolar RNAs (snoRNAs) are required for ribose 2'-O-methylation of eukaryotic ribosomal RNA. Many of the genes for this snoRNA family have remained unidentified in Saccharomyces cerevisiae, despite the availability of a complete genome sequence. Probabilistic modeling methods akin to those used in speech recognition and computational linguistics were used to computationally screen the yeast genome and identify 22 methylation guide snoRNAs, snR50 to snR71. Gene disruptions and other experimental characterization confirmed their methylation guide function. In total, 51 of the 55 ribose methylated sites in yeast ribosomal RNA were assigned to 41 different guide snoRNAs. PMID:10024243

Lowe, T M; Eddy, S R

1999-02-19

30

A Guide for Developing Standard Operating Job Procedures for the Screening & Grinding Process Wastewater Treatment Facility. SOJP No. 1.  

ERIC Educational Resources Information Center

This guide describes standard operating job procedures for the screening and grinding process of wastewater treatment facilities. The objective of this process is the removal of coarse materials from the raw waste stream for the protection of subsequent equipment and processes. The guide gives step-by-step instructions for safety inspection,…

Deal, Gerald A.; Montgomery, James A.

31

A Guide for Developing Standard Operating Job Procedures for the Screening & Grinding Process Wastewater Treatment Facility. SOJP No. 1.  

ERIC Educational Resources Information Center

|This guide describes standard operating job procedures for the screening and grinding process of wastewater treatment facilities. The objective of this process is the removal of coarse materials from the raw waste stream for the protection of subsequent equipment and processes. The guide gives step-by-step instructions for safety inspection,…

Deal, Gerald A.; Montgomery, James A.

32

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

NASA Astrophysics Data System (ADS)

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

2013-06-01

33

Screening and management of anal dysplasia and anal cancer in HIV-infected patients: a guide for practice.  

PubMed

People living with HIV infection have a significantly higher rate of anal cancer as compared with that of uninfected people. It is believed that high-grade anal dysplasia secondary to human papillomavirus infection is a precursor to anal cancer. Considering this, screening and treatment of high-grade anal dysplasia is a possible means of preventing the development of anal cancer. No national or international guidelines exist to guide practice for screening and management of anal dysplasia. On the basis of a review of research and expert recommendations, a guide to practice for screening and management of anal dysplasia and anal cancer is made for clinicians. PMID:20409734

Moran, Matt G; Barkley, Thomas W; Hughes, Cynthia B

2010-04-21

34

Slot scintillation detector modeling for digital radiography  

NASA Astrophysics Data System (ADS)

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

Alcón, E. P. Q.; Lopes, R. T.

2001-06-01

35

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

36

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

37

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

38

The DSM Guided Cannabis Screen (DSM-G-CS): Description, reliability, factor structure and empirical scoring with a clinical sample  

Microsoft Academic Search

Clinicians need cannabis-specific diagnostic screens compatible with DSM-IV-TR and proposed DSM-5. A clinical sample (n=174) completed the DSM-Guided-Cannabis Screen (DSM-G-CS) 21 and 11 criteria versions and three drug comparison measures. DSM-G-CS descriptive statistics, reliabilities, three factor analyses, and eight ROC and discriminant analyses evaluated construct validity and empirical scoring. DSM-G-CS reliabilities are .88 (21-items) and .85 (11-criteria). Factor analyses (FA)

Dale Alexander; Patrick Leung

2011-01-01

39

Shackleton's Antarctic Adventure: The Greatest Survival Story of All Time. Teacher's Guide To Accompany the Giant-Screen Film.  

ERIC Educational Resources Information Center

|This teacher's guide was developed to accompany the giant-screen film, "Shackleton's Antarctic Adventure". The activities featured use a multidisciplinary approach and target students ages 7 through 14. Teacher pages include background information and student pages include instructions and additional information for understanding the activity.…

Gibb, Reen

40

Taking It to the Pews: A CBPR-Guided HIV Awareness and Screening Project with Black Churches  

ERIC Educational Resources Information Center

|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…

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

2010-01-01

41

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

42

Cost-Effectiveness Analysis of Risk-Factor Guided and Birth-Cohort Screening for Chronic Hepatitis C Infection in the United States  

PubMed Central

Background No consensus exists on screening to detect the estimated 2 million Americans unaware of their chronic hepatitis C infections. Advisory groups differ, recommending birth-cohort screening for baby boomers, screening only high-risk individuals, or no screening. We assessed one-time risk assessment and screening to identify previously undiagnosed 40–74 year-olds given newly available hepatitis C treatments. Methods and Findings A Markov model evaluated alternative risk-factor guided and birth-cohort screening and treatment strategies. Risk factors included drug use history, blood transfusion before 1992, and multiple sexual partners. Analyses of the National Health and Nutrition Examination Survey provided sex-, race-, age-, and risk-factor-specific hepatitis C prevalence and mortality rates. Nine strategies combined screening (no screening, risk-factor guided screening, or birth-cohort screening) and treatment (standard therapy–peginterferon alfa and ribavirin, Interleukin-28B-guided (IL28B) triple-therapy–standard therapy plus a protease inhibitor, or universal triple therapy). Response-guided treatment depended on HCV genotype. Outcomes include discounted lifetime costs (2010 dollars) and quality adjusted life-years (QALYs). Compared to no screening, risk-factor guided and birth-cohort screening for 50 year-olds gained 0.7 to 3.5 quality adjusted life-days and cost $168 to $568 per person. Birth-cohort screening provided more benefit per dollar than risk-factor guided screening and cost $65,749 per QALY if followed by universal triple therapy compared to screening followed by IL28B-guided triple therapy. If only 10% of screen-detected, eligible patients initiate treatment at each opportunity, birth-cohort screening with universal triple therapy costs $241,100 per QALY. Assuming treatment with triple therapy, screening all individuals aged 40–64 years costs less than $100,000 per QALY. Conclusions The cost-effectiveness of one-time birth-cohort hepatitis C screening for 40–64 year olds is comparable to other screening programs, provided that the healthcare system has sufficient capacity to deliver prompt treatment and appropriate follow-on care to many newly screen-detected individuals.

Liu, Shan; Cipriano, Lauren E.; Holodniy, Mark; Goldhaber-Fiebert, Jeremy D.

2013-01-01

43

Generation of an external guide sequence library for a reverse genetic screen in Caenorhabditis elegans  

PubMed Central

Background A method for inhibiting the expression of particular genes using external guide sequences (EGSs) has been developed in bacteria, mammalian cells and maize cells. Results To examine whether EGS technology can be used to down-regulate gene expression in Caenorhabditis elegans (C. elegans), we generated EGS-Ngfp-lacZ and EGS-Mtgfp that are targeted against Ngfp-lacZ and Mtgfp mRNA, respectively. These EGSs were introduced, both separately and together, into the C. elegans strain PD4251, which contains Ngfp-lacZ and Mtgfp. Consequently, the expression levels of Ngfp-lacZ and Mtgfp were affected by EGS-Ngfp-lacZ and EGS-Mtgfp, respectively. We further generated an EGS library that contains a randomized antisense domain of tRNA-derived EGS ("3/4 EGS"). Examination of the composition of the EGS library showed that there was no obvious bias in the cloning of certain EGSs. A subset of EGSs was randomly chosen for screening in the C. elegans strain N2. About 6% of these EGSs induced abnormal phenotypes such as P0 slow postembryonic growth, P0 larval arrest, P0 larval lethality and P0 sterility. Of these, EGS-35 and EGS-83 caused the greatest phenotype changes, and their target mRNAs were identified as ZK858.7 mRNA and Lin-13 mRNA, respectively. Conclusion EGS technology can be used to down-regulate gene expression in C. elegans. The EGS library is a research tool for reverse genetic screening in C. elegans. These observations are potentially of great importance to further our understanding and use of C. elegans genomics.

Yan, Qitao; Zhao, Rui; Zheng, Wenlin; Yin, Changxin; Zhang, Bao; Ma, Wenli

2009-01-01

44

A Guide to Screening for the Early and Periodic Screening, Diagnosis and Treatment Program (EPSDT) Under Medicaid.  

ERIC Educational Resources Information Center

|The manual was designed to help public officials, physicians, nurses, and others to plan and implement an Early and Periodic Screening, Diagnosis and Treatment (EPSDT) program under Medicaid. Procedures for carrying out components of an EPSDT program are recommended. Part 1 discusses organization and administration of screening, diagnosis, and…

Frankenburg, William K.; North, A. Frederick, Jr.

45

An equatorial scintillation model  

NASA Astrophysics Data System (ADS)

Radiowave scintillation in the presence of natural and/or high altitude nuclear disturbances has the potential to disrupt numerous transionospheric radio and radar systems. This report develops a model characterizing the plasma density irregularities that produce scintillation in the naturally disturbed equatorial F layer. The model has been incorporated into Program WBMOD along with subroutines for computing both link geometry and scintillation indices, the latter by means of phase screen diffraction theory. The model is based on similarly extensive analysis of Wideband data from two equatorial stations. It describes irregularities at an effective height of 350 km that are isotropic across the geomagnetic field and elongated by a factor of 50 along the field and whose one dimensional spatial power spectrum obeys a single regime power law with a (negative) spectral index of 1.5. The height-integrated spectral strength of the irregularities is modeled as a function of solar epoch (sunspot number), the angle between the sunset terminator and the geomagnetic field line through the equatorial F layer point in question (a measure of seasonal and longitudinal variation), time after E-layer sunset on that field line, and the F-layer magnetic apex latitude of the point. The report also highlights a factor missing from complete characterization of the joint seasonal/longitudinal variation of scintillation, thought to depend upon thermospheric neutral winds.

Fremouw, E. J.; Robins, R. E.

1985-09-01

46

Synthesis of Potent Dishevelled PDZ Domain Inhibitors Guided by Virtual Screening and NMR Studies  

PubMed Central

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.

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

2011-01-01

47

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.

48

SCINTILLATION SPECTROMETER  

DOEpatents

A portable scintillation spectrometer is described which is especially useful in radio-biological studies for determining the uptake and distribution of gamma -emitting substances in tissue. The spectrometer includes a collimator having a plurality of apertures that are hexagonal in cross section. Two crystals are provided: one is activated to respond to incident rays from the collimator; the other is not activated and shields the first from external radiation.

Bell, P.R.; Francis, J.E.

1960-06-21

49

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

50

Taking It to the Pews: a CBPR-guided HIV awareness and screening project with black churches.  

PubMed

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. PMID:20528130

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

2010-06-01

51

Rapid bioassay-guided screening of toxic substances in vegetable oils that shorten the life of SHRSP rats.  

PubMed

It has been consistently reported that vegetable oils including canola oil have a life shortening effect in Stroke-Prone Spontaneously Hypertensive Rats (SHRSP) and this toxic effect is not due to the fatty acid composition of the oil. Although it is possible that the phytosterol content or type of phytosterol present in vegetable oils may play some role in the life shortening effect observed in SHRSP rats this is still not completely resolved. Furthermore supercritical CO2 fractionation of canola oil with subsequent testing in SHRSP rats identified safe and toxic fractions however, the compounds responsible for life shortening effect were not characterised. The conventional approach to screen toxic substances in oils using rats takes more than six months and involves large number of animals. In this article we describe how rapid bioassay-guided screening could be used to identify toxic substances derived from vegetable oils and/or processed foods fortified with vegetable oils. The technique incorporates sequential fractionation of oils/processed foods and subsequent treatment of human cell lines that can be used in place of animal studies to determine cytotoxicity of the fractions with structural elucidation of compounds of interest determined via HPLC-MS and GC-MS. The rapid bioassay-guided screening proposed would require two weeks to test multiple fractions from oils, compared with six months if animal experiments were used to screen toxic effects. Fractionation of oil before bio-assay enhances the effectiveness of the detection of active compounds as fractionation increases the relative concentration of minor components. PMID:20122175

Ratnayake, Sunil; Lewandowski, Paul

2010-02-02

52

Large volume flow-through scintillating detector  

DOEpatents

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

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

1995-01-01

53

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

54

A protein network-guided screen for cell cycle regulators in Drosophila  

PubMed Central

Background Large-scale RNAi-based screens are playing a critical role in defining sets of genes that regulate specific cellular processes. Numerous screens have been completed and in some cases more than one screen has examined the same cellular process, enabling a direct comparison of the genes identified in separate screens. Surprisingly, the overlap observed between the results of similar screens is low, suggesting that RNAi screens have relatively high levels of false positives, false negatives, or both. Results We re-examined genes that were identified in two previous RNAi-based cell cycle screens to identify potential false positives and false negatives. We were able to confirm many of the originally observed phenotypes and to reveal many likely false positives. To identify potential false negatives from the previous screens, we used protein interaction networks to select genes for re-screening. We demonstrate cell cycle phenotypes for a significant number of these genes and show that the protein interaction network is an efficient predictor of new cell cycle regulators. Combining our results with the results of the previous screens identified a group of validated, high-confidence cell cycle/cell survival regulators. Examination of the subset of genes from this group that regulate the G1/S cell cycle transition revealed the presence of multiple members of three structurally related protein complexes: the eukaryotic translation initiation factor 3 (eIF3) complex, the COP9 signalosome, and the proteasome lid. Using a combinatorial RNAi approach, we show that while all three of these complexes are required for Cdk2/Cyclin E activity, the eIF3 complex is specifically required for some other step that limits the G1/S cell cycle transition. Conclusions Our results show that false positives and false negatives each play a significant role in the lack of overlap that is observed between similar large-scale RNAi-based screens. Our results also show that protein network data can be used to minimize false negatives and false positives and to more efficiently identify comprehensive sets of regulators for a process. Finally, our data provides a high confidence set of genes that are likely to play key roles in regulating the cell cycle or cell survival.

2011-01-01

55

Scintillation counting apparatus  

Microsoft Academic Search

In the measurement of radiation by means of scintillation counters one ; drawback has been the scarcity of radiation counters which efficiently measure ; both gamma and beta radiation. There has also been the problem of scintillation ; counting in the face of external or background radiation. A scintillation ; counting apparatus is provided herein which measures scintillations arising from

Noakes

1975-01-01

56

Discovery of indolotryptoline antiproliferative agents by homology-guided metagenomic screening  

PubMed Central

Natural product discovery by random screening of broth extracts derived from cultured bacteria often suffers from high rates of redundant isolation, making it ever more challenging to identify novel biologically interesting natural products. Here we show that homology-based screening of soil metagenomes can be used to specifically target the discovery of new members of traditionally rare, biomedically relevant natural product families. Phylogenetic analysis of oxy-tryptophan dimerization gene homologs found within a large soil DNA library enabled the identification and recovery of a unique tryptophan dimerization biosynthetic gene cluster, which we have termed the bor cluster. When heterologously expressed in Streptomyces albus, this cluster produced an indolotryptoline antiproliferative agent with CaMKII? kinase inhibitory activity (borregomycin A), along with several dihydroxyindolocarbazole anticancer/antibiotics (borregomycins B–D). Similar homology-based screening of large environmental DNA libraries is likely to permit the directed discovery of new members within other previously rare families of bioactive natural products.

Chang, Fang-Yuan; Brady, Sean F.

2013-01-01

57

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

2013-03-21

58

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

59

Scintillator for radiation detection and process for producing the same  

Microsoft Academic Search

A scintillator for radiation detection obtained by coating a light reflective material in a thickness of 50 to 150 m by a screen printing method on the surface of a solid scintillator material substrate is excellent in uniformity, dimensional accuracy with high light output. When the light reflective material layer is covered with a synthetic resin film, adhesive strength of

M. Ishii; S. Akiyama; H. Ishibashi

1985-01-01

60

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

2012-01-31

61

Study of Organic Scintillators  

Microsoft Academic Search

The scintillation counting behavior of a group of fifty-five pure crystalline organic compounds has been extensively studied. The data obtained have been analyzed with the goal of developing a better understanding of the scintillation process and of scintillator behavior.The materials were carefully purified, and massive crystals were grown. Relative scintillation average-pulse-height efficiencies at 30°C and —70°C for cobalt-60 gamma-ray excitation,

Raymond C. Sangster; John W. Irvine

1956-01-01

62

Extruded Plastic Scintillation Detectors  

Microsoft Academic Search

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

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

1999-01-01

63

Extruded plastic scintillation detectors  

Microsoft Academic Search

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

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

1999-01-01

64

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

65

Scintillator materials for calorimetry  

Microsoft Academic Search

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.

Marvin J. Weber

1994-01-01

66

The scintillating grid illusion is enhanced by binocular viewing  

PubMed Central

The scintillating grid illusion is an intriguing stimulus consisting of a grey grid on a black background, with white discs at the grid intersections. Most viewers perceive illusory “scintillating” black discs within the physical white discs, especially at non-fixated locations. Here, we report for the first time that this scintillation percept is stronger when the stimulus is viewed binocularly than when it is presented to only one eye. Further experiments indicate that this is not simply because two monocular percepts combine linearly, but involves a specifically cyclopean contribution (Schrauf & Spillmann, 2000). However, the scintillation percept does not depend on the absolute disparity of the stimulus relative to the screen. In an intriguing twist, although the basic illusion shows more scintillation when viewed binocularly, when the illusion is weakened by shifting the discs away from the grid intersections, scintillation becomes stronger with monocular viewing.

Read, Jenny C. A.; Robson, Joseph H.; Smith, Christopher L.; Lucas, Andrew D.

2012-01-01

67

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

68

An equatorial scintillation model  

Microsoft Academic Search

Radiowave scintillation in the presence of natural and\\/or high altitude nuclear disturbances has the potential to disrupt numerous transionospheric radio and radar systems. This report develops a model characterizing the plasma density irregularities that produce scintillation in the naturally disturbed equatorial F layer. The model has been incorporated into Program WBMOD along with subroutines for computing both link geometry and

E. J. Fremouw; R. E. Robins

1985-01-01

69

A High Z Scintillator  

Microsoft Academic Search

Thallium Chloride, activated with iodides, has been found to scintillate. Photopeaks for the Cs137 .662 Mev gamma energy have been obtained with several crystals, while many other TICI crystals, prepared with different iodides of varying low concentration show smaller scintillation response. Pulse height varies with the activators used. The consistently largest output to date is measured for TICI(Be,I). A maximum

K. H. Rosette; M. R. Farukhi; Gerald R. Kramer; Carl Swinehart; R. Hofstadter

1970-01-01

70

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

71

Scintillation Properties of High Light Yield Scintillators  

Microsoft Academic Search

The scintillation properties of$ LuI_3: Ce^3+$(pure, 0.5%, 2%, and 5%$ Ce^3+$), a new member of the generation of$ Ce^3+$doped lanthanide trihalide scintillators, are presented. This material has a calculated density of 5.6$ g\\/cm^3$and an atomic number$Z_eff$of 60.2. Under optical and X-ray excitation,$ Ce^3+$emission is observed to peak at 472 and 535 nm. A high light yield of 76 000 photons

M. D. Birowosuto; P. Dorenbos; C. W. E. vanEijk; K. W. Kramer; H. U. Gudel

2005-01-01

72

Design and Construction Elements for Scintillating Fibre Tracking Detectors  

NASA Astrophysics Data System (ADS)

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

Sharpe, Jason Ray

73

Integration of Microfractionation, qNMR and Zebrafish Screening for the In Vivo Bioassay-Guided Isolation and Quantitative Bioactivity Analysis of Natural Products  

PubMed Central

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.

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

74

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

2013-05-21

75

Breast and Cervical Cancer Programs in Your Community: A Guide for Outreach, Screening, and Follow-up Care.  

National Technical Information Service (NTIS)

This guide is designed to help concerned citizens and health care groups in communities across the country reduce illness and death from breast and cervical cancers by helping them achieve three goals; educating women about the importance of routine scree...

1999-01-01

76

Patient selection guidelines in MR-guided focused ultrasound surgery of uterine fibroids: a pictorial guide to relevant findings in screening pelvic MRI  

Microsoft Academic Search

Uterine leiomyomas (fibroids), the most common benign tumor in women of childbearing age, can cause symptoms including dysmenorrhea,\\u000a menorrhagia, urinary symptoms, pain and infertility. Hysterectomy is a common approach to treating uterine fibroids, and less\\u000a invasive surgical approaches such as myomectomy and uterine artery embolization also have been shown to alleviate symptoms.\\u000a Magnetic resonance-guided focused ultrasound surgery (MRgFUS) is the

Sang-Wook Yoon; Chan Lee; Sun Hee Cha; Jeong-Sik Yu; Young-Jeong Na; Kyoung Ah Kim; Sang-Geun Jung; Seung-Jo Kim

2008-01-01

77

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

78

The physics analysis and experiment study of zinc sulphide scintillator for fast neutron radiography  

NASA Astrophysics Data System (ADS)

Fast neutron radiography is a promising application for accelerator based neutron sources. The potential effectiveness of this technique depends on the development of suitable imaging detectors for fast neutrons. Zinc sulphide based scintillators have the largest light output per event in the family of imaging scintillators used so far in fast neutron radiography. This paper investigated different aspects of this scintillator in order to determine the factors which might affect the light output. A mathematical model was established to estimate effectiveness of this scintillator. Zinc sulphide screens were prepared with ZnS particles of different concentrations in polypropylene matrix. A 14 MeV fast neutron source was used in the experiments. The light output was detected using a CCD camera or a film coupled to the scintillator screen. The results showed that the optimum scintillators is around 3 mm in thickness with the weight ratio of 2:1 for ZnS and polypropylene.

Tang, Bin; Wu, Yang; Li, Hang; Sun, Yong; Huo, Heyong; Liu, Bin; Tang, Ke; Yin, Wei; Chao, Chao

2013-11-01

79

Liquid Scintillator Detectors  

NASA Astrophysics Data System (ADS)

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

Oberauer, L.

2013-02-01

80

Scintillation Analysis System.  

National Technical Information Service (NTIS)

The patent application describes a system for the combustion preparation of samples for scintillation analysis comprising a combustion tube containing a combustion catalyst, a chimney tube positioned within the combustion tube and resting on the catalyst ...

J. I. Peterson

1970-01-01

81

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

82

L-Band TEC Measurements and Lower Frequency Scintillation  

NASA Astrophysics Data System (ADS)

Signal amplitude measurements from the GPS satellites are currently limited to L-band frequencies above 1 GHz, which often remain unaffected by conditions causing even severe scintillation at more sensitive lower frequencies. Use of differential carrier phase data from dual frequency receivers to drive phase screen models and estimate scintillation at other frequencies is one potential means of monitoring scintillation over a wider range of frequencies. However, this process is complicated by the presence of a diffractive component in the L-band signal phase which can obscure the true structure in total electron content (TEC) needed as input to phase screen models. Signal amplitudes and phases at L1 and L2 frequencies (1.57 and 1.23 GHz, respectively) are calculated after propagation through one-dimensional power-law phase screens and then the resulting differential carrier phase compared with the initial phase values in the screen. Scintillation at a variety of frequencies is then computed from both the original screen and the simulated differential carrier phase, and the two results compared to examine the effects of the unobservable diffractive phase component contained in observational TEC data. Initial results show an increase of ~10% in S4 index computed at 250 MHz from simulated differential carrier phase compared to the direct phase screen computation. These results suggest that under many conditions L-band TEC observations can be used effectively to estimate VHF and UHF scintillation over a wide range of scintillation levels, and that the differences resulting from use of observed TEC instead of true ionospheric phase can be accounted for by a relatively simple correction factor.

Pedersen, T. R.; Beach, T. L.

2003-12-01

83

Rational design of binary halide scintillators via data mining  

NASA Astrophysics Data System (ADS)

We introduce a new search strategy for the development of novel inorganic scintillators. For designing new scintillation host media having the improved properties, the potential candidate materials were chosen by using a chemical selection scheme based on a multi-dimensional similarity metric. For the quantitative assessment of the chosen materials, predictive models based on informatics were built by correlating a set of key parameters which reflect the features of the host materials with the performance of inorganic scintillators. The resulting design rules generated from the relationships serve as a guide to identify HfI4 and TaI5 as two new host lattices with high light yield. The method we have outlined here serves as a new computational template based statistical learning method to search for new inorganic scintillators with targeted properties.

Kong, Chang Sun; Rajan, Krishna

2012-07-01

84

Scintillation behavior of Airy beam  

NASA Astrophysics Data System (ADS)

We make an analysis on scintillation behavior of Airy beam using the Rytov method. To this end, scintillation index is formulated for a single receiver coordinate location. Area scintillation expressions are also derived. At peaks of receiver intensity, Airy beam is found to offer quite less scintillation at width values of around 1.6cm. Furthermore, smaller values of the exponential truncation factor are also seen to cause less scintillation. When compared to Gaussian beam, on equal source and received power basis, it is observed that Airy beam will generally have less area scintillation.

Eyyubo?lu, Halil T.

2013-04-01

85

Best Practice in Preschool Screening.  

ERIC Educational Resources Information Center

|This brief guide outlines best practices in preschool screening for the presence of possible disabilities. It covers: a definition of screening, its history, the rationale for screening, requirements for effective screening measures (reliability, validity, fairness, utility), models for preschool screening, evaluation of screening procedures, and…

Rosenkoetter, Sharon E.; Wanska, Susan K.

86

Revisiting the Wilson-Jungner criteria: How can supplemental criteria guide public health in the era of genetic screening?  

PubMed

PURPOSE:: Advances in technology have made newborn screening for more than 50 inborn errors of metabolism possible using a dried blood sample. A framework is proposed that public health practitioners may use when considering candidate disorders for newborn screening panels. METHODS:: The framework expands on the 10 Wilson-Jungner criteria with the addition of 11 criteria specific to newborn screening. A calculation, the "pNBS Decision Score," is used to quantify results and rank candidate disorders. RESULTS:: The pNBS Decision Scores that were calculated for phenylketonuria (OMIM# 261600), cystic fibrosis (OMIM# 219700), Pompe disease (OMIM# 232300), and severe combined immunodeficiency (OMIM# 102700) support their inclusion as newborn screening disorders. The pNBS Decision Score suggests that Krabbe disease (OMIM# 245200) is not a candidate disorder for inclusion at this time. CONCLUSION:: The proposed framework adds to the ability of policy makers to quantify an essential portion of the process for adding disorders to newborn screening panels. Other factors such as ethical, legal, and social issues, clinical utility, and advocacy are also part of the policy process. The framework is not intended to replace existing nomination processes but rather to enhance those processes by encouraging iterative review of newborn screening-specific criteria. The use of the framework will provide consistency across a portion of the decision process. The public health community should take the opportunity to revisit the screening determinants of the Wilson-Jungner criteria from a 21st century perspective. The results suggest that this framework provides the public health practitioner with a consistent process for making an evidence-based decision. PMID:21983595

Petros, Michael

2011-10-01

87

Thermally stimulated optical scintillations in preheated plastic scintillators  

Microsoft Academic Search

PVT-based plastic scintillators, irrespective of their radiation history, are found to exhibit thermally stimulated optical scintillations in the temperature interval 40-80°C following a preheat to 200°C or above and cooling to RT. Maximum scintillation activity occurs near 65°C, which is the glass transition temperature Tg of the scintillators. Comparing our results with the literature data of similar work it is

M. S. Jahan; C. Cox; D. R. Ermer; D. W. Jones; D. W. Cooke

1992-01-01

88

Scintillation mechanism and efficiency of ternary scintillator thin films  

Microsoft Academic Search

The scintillation mechanism of ternary plastic scintillators, excited by ions, was studied in order to correlate the scintillation efficiency as a function of the thickness to the energy transfer process between the light emitters embedded in the polymer. A numerical model for describing the energy transfer from the matrix to the primary emitter, and from the primary emitter to the

A. Quaranta; A. Vomiero; G. Della Mea

2002-01-01

89

Scintillation efficiencies of scintillators based on white oils  

Microsoft Academic Search

Some preliminary results on the comparison of scintillation efficiencies of scintillators based on two white oils are described. It is shown that a new solvent, technical white oil, has a better scintillation efficiency than that of medicinal paraffin. A possible reason for this higher efficiency is discussed.

B. M. Jasani

1972-01-01

90

A photon transport model code for use in scintillation detectors  

Microsoft Academic Search

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

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

2004-01-01

91

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

92

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

93

BAM R68: Scintillation Fluid  

Center for Food Safety and Applied Nutrition (CFSAN)

... BAM R68: Scintillation Fluid. January 2001. Bacteriological Analytical Manual. R68 Scintillation Fluid. 2,5 Diphenyloxazole, 5.0 g. ... More results from www.fda.gov/food/foodscienceresearch/laboratorymethods

94

Gamma-ray scintillation detector  

Microsoft Academic Search

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

H. Tatsuta; S. Kumazawa

1977-01-01

95

Ionospheric scintillation: A brief review  

NASA Astrophysics Data System (ADS)

Irregular diffraction of radio signals by the global ionosphere is studied to predict scintillation using easily measured geophysical parameters. Using a network of equatorial stations it was possible to measure and model the average scintillation characteristics and to relate them to geophysical parameters such as solar flux and geomagnetic indices. Typical models for various stations are shown, including the variations of scintillation as predicted and as measured. The scintillation in auroral regions and the phase distortion caused by the ionosphere are also discussed.

Mullen, J. P.; Aarons, J.; MacKenzie, E. M.

96

Introducing the Community Guide's Reviews of Evidence on Interventions to Increase Screening for Breast, Cervical, and Colorectal Cancers  

Microsoft Academic Search

these deaths were due to lung (31%), prostate (10%), and colorectal cancers (10%). Among women, most deaths were from lung (25%), breast (15%), and colorectal cancers (10%), with an additional 1% from cervical cancers. For breast, cervical, and colorectal cancers, routine screening is recommended by the U.S. Preventive Ser- vices Task Force (USPSTF) 3 -6 —an independent panel of experts

Rosalind A. Breslow; Barbara K. Rimer; Roy C. Baron; Ralph J. Coates; Jon Kerner; Katherine M. Wilson; Nancy C. Lee; Patricia Dolan Mullen; Steven S. Coughlin; Peter A. Briss

2008-01-01

97

A Guide to Administration, Diagnosis, and Treatment for the Early and Periodic Screening, Diagnosis, and Treatment Program (EPSDT) Under Medicaid.  

ERIC Educational Resources Information Center

|Provided are guidelines on administration, diagnosis, and treatment in federally funded EPSDT--Early and Periodic Screening, Diagnosis, and Treatment Programs, a system for providing health care services to Medicaid-eligible children. Detailed in part one are factors involved in developing EPSDT programs. Four chapters consider the need for…

Hass, Gerald; Scovell, Melvin

98

Testing Scintillators for Homeland Security  

NASA Astrophysics Data System (ADS)

Scintillating nanoparticles have a bright future in radiation detection, especially in the area of detecting nuclear devices. As part of a UTA nanoparticle scintillator development team funded by the Department of Homeland Security, I have been developing a scintillator test stand using various radioactive sources and a Hamamatsu S3590 photodiode. I will present initial test results.

Bourbeau, James; Brandt, Andrew; Kenarangui, Rasool; Weiss, Alex; Chen, Wei

2011-10-01

99

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

100

Design Rules for Ce-Activated Scintillating Radiation Detection Materials: Compromises Between Luminosity and Stopping Power  

Microsoft Academic Search

This paper presents new development methods for property-screening design rules, using structure-property relationships for two fundamental properties of activated scintillating based gamma radiation detection-luminosity and stopping power. The first and most evident goal in developing screening models of luminosity and stopping power, as indicated by the weight and electron densities, is to obtain new candidate cerium scintillating materials. However, a

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

2008-01-01

101

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

102

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

103

New Lutetium Silicate Scintillators  

Microsoft Academic Search

Cerium-doped lutecium orthosilicate (LSO) is the most promising scintillator discovered in almost five decades. It exhibits a unique combination of important properties for x and gamma-ray spectroscopy: high density, fast decay, and large light yield. However, the practical use of LSO is hindered by difficulties related to its fabrication as a single crystal by the Czochralski method. We report on

Eric Bescher; S. R. Robson; J. D. Mackenzie; B. Patt; J. Iwanczyk; E. J. Hoffman

2000-01-01

104

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

105

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

106

SCINTILLATION EXPOSURE RATE DETECTOR  

DOEpatents

A radiation detector for gamma and x rays is described. The detector comprises a scintillation crystal disposed between a tantalum shield and the input of a photomultiplier tube, the crystal and the shield cooperating so that their combined response to a given quantity of radiation at various energy levels is substantially constant.

Spears, W.G.

1960-11-01

107

Towards two-dimensional brachytherapy dosimetry using plastic scintillator: new highly efficient water equivalent plastic scintillator materials.  

PubMed

Plastic scintillator (PS) has been proposed for both one- and two-dimensional (1D and 2D) dose measurements for radiation therapy applications. For low-energy photon modalities (e.g., brachytherapy), an efficient water equivalent scintillator is needed. To perform 2D measurements, a high localization of the scintillation process is required. Guided by comparison of the mass energy absorption coefficients as a function of energy and of the dose distribution as a function of distance from the radioactive source, as modeled by Monte Carlo photon transport simulation, a small quantity of medium atomic number (Z) atoms (4% Cl) was incorporated in a polyvinyl toluene (PVT) based PS to approximate closely (within 10%) the radiological properties of water in the 20-662 keV energy range. However, the scintillation efficiency of commercial PS mixtures drops as much as 70% when loaded with high atomic number additives. We developed experimental techniques to assess the scintillation efficiency and locality of 15 new PS mixtures. These mixtures differ by the type of the scintillation dyes and the type of compound containing the medium Z atoms (chlorine). To achieve higher material stability, 4-chlorostyrene was used as a loading compound to ensure polymerization with the PVT base. Two of the new PS materials exhibited scintillation efficiencies within 30% of one of the most efficient commercially available products (BC-400), which is not water equivalent at such low energies. These new scintillator materials are promising candidates for the development of an accurate and efficient radiation dosimetry method not only for brachytherapy, but also for superficial and diagnostic applications. PMID:10501051

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

1999-08-01

108

Cerium compounds as scintillators  

SciTech Connect

Stoichiometric Ce-materials with negligible Ce-Ce interactions should have superior scintillator properties. We present two materials: CeF{sub 3} and Ce{sub x}La{sub 1-x}P{sub 5}O{sub 14}. While cerium trifluoride is a known scintillator, pentaphosphate is of a limited usefulness, except as a remarkable model material. We show that quenching in fluoride is responsible for loss of 50% of the light output and is the cause of the, so-called, ultra fast component (2 ns). Light output of fluoride (about 50% of BGO) could be significantly improved. Deeper understanding of Ce-systems is needed to fully exploit their potentials. 10 figs., 6 refs.

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

1991-12-31

109

Cerium compounds as scintillators  

SciTech Connect

Stoichiometric Ce-materials with negligible Ce-Ce interactions should have superior scintillator properties. We present two materials: CeF{sub 3} and Ce{sub x}La{sub 1-x}P{sub 5}O{sub 14}. While cerium trifluoride is a known scintillator, pentaphosphate is of a limited usefulness, except as a remarkable model material. We show that quenching in fluoride is responsible for loss of 50% of the light output and is the cause of the, so-called, ultra fast component (2 ns). Light output of fluoride (about 50% of BGO) could be significantly improved. Deeper understanding of Ce-systems is needed to fully exploit their potentials. 10 figs., 6 refs.

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

1991-01-01

110

Scintillator spent fuel monitor  

SciTech Connect

A monitor for rapidly measuring the gross gamma-ray flux immediately above spent fuel assemblies in underwater storage racks has been developed. It consists of a plastic scintillator, photomultiplier, collimator, and a small battery-powered electronics package. The crosstalk from an isolated fuel assembly to an adjacent void is only about 2%. The mean difference between the measured gamma-ray flux and the flux estimated from the declared burnup and cooling time with a simple formula is 22%.

Moss, C.E.; Nixon, K.V.; Bernard, W.

1980-01-01

111

Lunar components in Lunping scintillations  

SciTech Connect

The authors report on an anlysis of a 14 year data set of ionospheric scintillation data for 136 MHz signals transmitted from a Japanese satellite. They use a lunar age superposition method to analyze this data, breaking the data into blocks by seasons of the year. They observe a number of different scintillation types in the record, as well as impacts of lunar tides on the time record. They attempt to provide an origin for the different scintillation types.

Koster, J.R.; Lue, H.Y.; Wu, Hsi-Shu [Fu Jen Univ., Taipei (Taiwan, Province of China); Huang, Yinn-Nien [Ministry of Transportation and Telecommunications, Taipei (Taiwan, Province of China)

1993-08-01

112

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/cm2. 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 Gd2O2S: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

113

Statistical analysis of scintillation data  

SciTech Connect

The Nakagami-m distribution has traditionally been used successfully to model the probability characteristics of ionospheric scintillations at UHF. This report investigates the distribution properties of scintillation data in the L-band range. Specifically, the appropriateness of the Nakagami-m and lognormal distributions is tested. Briefly the results confirm that the Nakagami-m is appropriate for UHF but not for L-band scintillations. The lognormal provides a better fit to the distribution of L-band scintillations and is an adequate model allowing for an error of + or - 0.1 or smaller in predicted probability with a sample size of 256.

Chua, S.; Noonan, J.P.; Basu, S.

1981-09-01

114

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

115

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

116

Simulating Moving Features in Pulsar Scintillation Arcs  

NASA Astrophysics Data System (ADS)

Pulsar scintillation often shows organized and simple structure in a power spectrum analysis. In particular, the power in the secondary spectrum is frequently organized along parabolas that can be identified with thin scattering screens in the interstellar medium. Hill et al. (2005) showed an example in which substructure moved along a parabolic path in accord with the known motion of the pulsar across the sky and the derived distance to the scattering screen. We report results of a simulation in which coherent electromagnetic waves are propagated through a turbulent phase-changing screen causing interference effects at the observer. The inhomogeneities in the screen are assumed to have a Kolmogorov spectrum and are localized in distinct clouds embedded in the screen. We find movement in the secondary spectrum substructure that is consistent with the observations reported by Hill et al. (2005). We comment on the physical implications of the isolated substructure and its persistence in both the simulation and the observations. This work was supported by the National Science Foundation.

Myers, J. A.; Rudolph, M. L.; Stinebring, D. R.; Coles, W. A.; Rickett, B. J.

2005-12-01

117

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

118

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

PubMed

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

Schauer, Petr

119

DESIGN NOTE: Simulation study for a single TOF scintillator using GEANT4  

NASA Astrophysics Data System (ADS)

A time-of-flight (TOF) detector system based on plastic scintillators will be used in the Beijing spectrometer III (BSE-III) at Beijing Electron Positron Collider. In this note the result of a detailed Monte Carlo simulation for single TOF scintillator modules, based on GEANT4, is presented. The intrinsic time resolution is obtained. Also given is a comparison of two kinds of plastic scintillation material—BC404 and BC408 of different thicknesses, coupling mode with PMT and geometry. These simulation results could serve as an important guide for the BES-III TOF design.

Li-Ming, Zhang; Hai-Ping, Peng; Zi-Ping, Zhang; Hong-Fang, Chen; Ming, Shao; Jian, Wu

2004-07-01

120

Development of intrinsic IPT scintillator  

NASA Astrophysics Data System (ADS)

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 commercial plastic scintillator, NE 110.

Bross, Alan D.

1989-07-01

121

Development of radiation hard scintillators  

NASA Astrophysics Data System (ADS)

The authors have demonstrated that the radiation stability of scintillators made from styrene polymer is very much improved by compounding with pentaphenyl trimethyl trisiloxane (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 from monomer give only 50% to 60% relative to the reference, BC408. When oil modified scintillators using both p-terphenyl and tetra phenyl butadiene 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.; Harmon, J.; Biagtan, E.; Schueneman, G.; Senchishin, V.; Gustfason, H.

1993-11-01

122

Extruding plastic scintillator at Fermilab  

SciTech Connect

An understanding of the costs involved in the production of plastic scintillators and the development of a less expensive material have become necessary with the prospects of building very large plastic scintillation detectors. Several factors contribute to the high cost of plastic scintillating sheets, but the principal reason is the labor-intensive nature of the manufacturing process. In order to significantly lower the costs, the current casting procedures had to be abandoned. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. This concept was tested and high quality extruded plastic scintillator was produced. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. This paper will discuss the characteristics of extruded plastic scintillator and its raw materials, the different manufacturing techniques and the current R&D program at Fermilab.

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

2003-10-31

123

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

124

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

125

Scintillation light transport and detection  

NASA Astrophysics Data System (ADS)

The MORSE neutron gamma-ray transport code has been modified to allow for the transport of scintillation light. This modified code is used to analyze the light collection characteristics of a large liquid scintillator module (18 × 18 × 350 cm3).

Gabriel, T. A.; Lillie, R. A.

1987-08-01

126

Scintillation light transport and detection  

SciTech Connect

The MORSE neutron gamma-ray transport code has been modified to allow for the transport of scintillation light. This modified code is used to analyze the light collection characteristics of a large liquid scintillator module (18 x 18 x 350 cm/sup 3/).

Gabriel, T.A.; Lillie, R.A.

1986-08-01

127

Development of radiation hard scintillators.  

National Technical Information Service (NTIS)

Substantial improvements have been made in the radiation hardness of plastic scintillators. Cylinders of scintillating materials 2.2 cm in diameter and 1 cm thick have been exposed to 10 Mrads of gamma rays at a dose rate of 1 Mrad/h in a nitrogen atmosph...

A. Pla-Dalmau D. Woods F. Markley G. Foster R. Blackburn

1992-01-01

128

Variation of the ionospheric scintillation index with elevation angle of the transmitter  

NASA Astrophysics Data System (ADS)

We have analyzed GPS data from 2007-2011 to determine the nature of variation of scintillation index with elevation of the direction of propagation at an observing point Warsaw, Poland, and Hornsund, Svalbard. To compare with the theory, the intensity scintillation index is simulated as a function of elevation angle, azimuth, magnetic field inclination, and shape of irregularities, using the phase screen model of scintillation as formulated by Rino (1979). Data analysis has been done for the seasonal as well as geomagnetic activity dependence of ionospheric scintillation. Scintillation index is a power-law function of the cosecant of the elevation angle. Results show that the power law strongly depends on the form of irregularities, being larger than in isotropic case for irregularities with dimension along the magnetic field direction smaller than those across the magnetic field. The present work also shows the need to use experimentally derived dependence on elevation.

Priyadarshi, Shishir; Wernik, Andrzej W.

2013-04-01

129

Variation of the ionospheric scintillation index with elevation angle of the transmitter  

NASA Astrophysics Data System (ADS)

We have analyzed GPS data from 2007-2011 to determine the nature of variation of scintillation index with elevation of the direction of propagation at an observing point Warsaw, Poland, and Hornsund, Svalbard. To compare with the theory, the intensity scintillation index is simulated as a function of elevation angle, azimuth, magnetic field inclination, and shape of irregularities, using the phase screen model of scintillation as formulated by Rino (1979). Data analysis has been done for the seasonal as well as geomagnetic activity dependence of ionospheric scintillation. Scintillation index is a power-law function of the cosecant of the elevation angle. Results show that the power law strongly depends on the form of irregularities, being larger than in isotropic case for irregularities with dimension along the magnetic field direction smaller than those across the magnetic field. The present work also shows the need to use experimentally derived dependence on elevation.

Priyadarshi, Shishir; Wernik, Andrzej W.

2013-10-01

130

Scintillations of Laguerre Gaussian beams  

NASA Astrophysics Data System (ADS)

By using the Rytov method, we formulate and numerically evaluate the scintillations of Laguerre Gaussian beams in weak atmospheric turbulence. Our results indicate that at on-axis positions, Laguerre Gaussian beams with zero angular mode number will have less scintillations than fundamental Gaussian beams, where the amount of scintillations will further decrease with rising radial mode number. When off-axis positions are considered, this situation reverses however, and the scintillations of Laguerre Gaussian beams become generally higher than the fundamental Gaussian beam. Plotted against the source size, the on-axis scintillations of Laguerre Gaussian beams fall below the fundamental Gaussian beam, following the same trend as the fundamental Gaussian beam all throughout the source size range examined.

Eyyubo?lu, H. T.; Baykal, Y.; Ji, X.

2010-03-01

131

Scintillator based beta batteries  

NASA Astrophysics Data System (ADS)

Some long-term, remote applications do not have access to conventional harvestable energy in the form of solar radiation (or other ambient light), wind, environmental vibration, or wave motion. Radiation Monitoring Devices, Inc. (RMD) is carrying out research to address the most challenging applications that need power for many months or years and which have undependable or no access to environmental energy. Radioisotopes are an attractive candidate for this energy source, as they can offer a very high energy density combined with a long lifetime. Both large scale nuclear power plants and radiothermal generators are based on converting nuclear energy to heat, but do not scale well to small sizes. Furthermore, thermo-mechanical power plants depend on moving parts, and RTG's suffer from low efficiency. To address the need for compact nuclear power devices, RMD is developing a novel beta battery, in which the beta emissions from a radioisotope are converted to visible light in a scintillator and then the visible light is converted to electrical power in a photodiode. By incorporating 90Sr into the scintillator SrI2 and coupling the material to a wavelength-matched solar cell, we will create a scalable, compact power source capable of supplying milliwatts to several watts of power over a period of up to 30 years. We will present the latest results of radiation damage studies and materials processing development efforts, and discuss how these factors interact to set the operating life and energy density of the device.

Rensing, Noa M.; Tiernan, Timothy C.; Shirwadkar, Urmila; O'Dougherty, Patrick; Freed, Sara; Hawrami, Rastgo; Squillante, Michael R.

2013-05-01

132

Development of multi-color scintillator based X-ray image intensifier  

Microsoft Academic Search

A multi-color scintillator based high-sensitive, wide dynamic range and long-life X-ray image intensifier has been developed. An europium activated Y2O2S scintillator, emitting red, green and blue photons of different intensities, is utilized as the output fluorescent screen of the intensifier. By combining this image intensifier with a suitably tuned high sensitive color CCD camera, it is possible for a sensitivity

Koichi Nittoh; Chikara Konagai; Takashi Noji

2004-01-01

133

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

134

Fast, Long-Wavelength Scintillators and Waveshifters  

NASA Astrophysics Data System (ADS)

Studies are presented of new blue-green to red emitting scintillator and waveshifter materials for tracking and calorimetric applications for the detection of ionizing radiation. Materials include plastic scintillators, liquid scintillators, and plastic scintillating and waveshifting fibers. Program goals are to develop faster and more efficient detection media for a variety of experimental applications.

Andert, K.; Baumbaugh, B.; Brothers, A.; David, A.; Gunther, H.; Gurrola, J.; Karmgard, D.; Madlem, T.; Marchant, J.; McGough, P.; McKenna, M.; Ruchti, R.; Thompson, J.; Vigneault, M.; Hernandez, L.; Hurlbut, C.

2006-04-01

135

Interstellar Seeing. I. Superresolution Techniques Using Radio Scintillation  

Microsoft Academic Search

Interstellar scintillation can be used to probe transverse sizes of radio\\u000asources on scales inaccessible to the nominal resolution of any terrestrial\\u000atelescope, e.g. $\\\\lesssim 10^{-6}$ arc sec. Methodology is presented that\\u000aexploits this superresolution phenomenon for both single aperture and\\u000ainterferometer observations. The treatment applies to the saturated\\u000a(strong-scattering) regime and holds for both thin screens and extended media.

J. M. Cordes

2000-01-01

136

Interstellar Seeing. I. Superresolution Techniques Using Radio Scintillation  

Microsoft Academic Search

Interstellar scintillation can be used to probe transverse sizes of radio sources on scales inaccessible to the nominal resolution of any terrestrial telescope, e.g. $\\\\lesssim 10^{-6}$ arc sec. Methodology is presented that exploits this superresolution phenomenon for both single aperture and interferometer observations. The treatment applies to the saturated (strong-scattering) regime and holds for both thin screens and extended media.

J. M. Cordes

2000-01-01

137

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

138

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

139

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

140

LIQUID SCINTILLATION COUNTING OF TRITIUM  

Microsoft Academic Search

The advantages and drawbacks of liquid scintillation counting of tritium ; are enumerated. It is shown how to determine the counting efficiency by using an ; external gamma source, instead of internal standards. (T.F.H.);

Okano

1961-01-01

141

Scintillator fiber optic long counter  

DOEpatents

A flat response position sensitive neutron detector capable of providing neutron spectroscopic data utilizing scintillator fiber optic filaments embedded in a neutron moderating housing having an open end through which neutrons enter to be detected is described. 11 figures.

McCollum, T.; Spector, G.B.

1994-03-29

142

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

143

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

144

Scintillating optical fibers in mammography  

Microsoft Academic Search

Measurements of the MTF and the DQE, on images obtained using a scintillating glass optical fiber system coupled to a mammography film, are displayed in comparison with the measurements obtained by a standard mammography cassette using the same film and the same X-ray dose. The final results are favourable to the scintillating fibers.The use of a CCD read-out in the

G. Gennaro; M. Malvestio; G. Zanella; R. Zannoni

1996-01-01

145

Ionospheric Scintillation Effects on GPS  

NASA Astrophysics Data System (ADS)

. Ionospheric scintillation of Global Positioning System (GPS) signals threatens navigation and military operations by degrading performance or making GPS unavailable. Scintillation is particularly active, although not limited to, a belt encircling the earth within 20 degrees of the geomagnetic equator. As GPS applications and users increases, so does the potential for detrimental impacts from scintillation. We examined amplitude scintillation data spanning seven years from Ascension Island, U.K.; Ancon, Peru; and Antofagasta, Chile in the Atlantic/Americas longitudinal sector at as well as data from Parepare, Indonesia; Marak Parak, Malaysia; Pontianak, Indonesia; Guam; and Diego Garcia, U.K.; in the Pacific longitudinal sector. From these data, we calculate percent probability of occurrence of scintillation at various intensities described by the S4 index. Additionally, we determine Dilution of Precision at one minute resolution. We examine diurnal, seasonal and solar cycle characteristics and make spatial comparisons. In general, activity was greatest during the equinoxes and solar maximum, although scintillation at Antofagasta, Chile was higher during 1998 rather than at solar maximum.

Steenburgh, R. A.; Smithtro, C.; Groves, K.

2007-12-01

146

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

147

Optimisation of nasal swab analysis by liquid scintillation counting.  

PubMed

When responding to an emergency radiological incident, rapid methods are needed to provide the physicians and radiation protection personnel with an early estimation of possible internal dose resulting from the inhalation of radionuclides. This information is needed so that appropriate medical treatment and radiological protection control procedures can be implemented. Nasal swab analysis, which employs swabs swiped inside a nostril followed by liquid scintillation counting of alpha and beta activity on the swab, could provide valuable information to quickly identify contamination of the affected population. In this study, various parameters (such as alpha/beta discrimination, swab materials, counting time and volume of scintillation cocktail etc) were evaluated in order to optimise the effectiveness of the nasal swab analysis method. An improved nasal swab procedure was developed by replacing cotton swabs with polyurethane-tipped swabs. Liquid scintillation counting was performed using a Hidex 300SL counter with alpha/beta pulse shape discrimination capability. Results show that the new method is more reliable than existing methods using cotton swabs and effectively meets the analysis requirements for screening personnel in an emergency situation. This swab analysis procedure is also applicable to wipe tests of surface contamination to minimise the source self-absorption effect on liquid scintillation counting. PMID:22562962

Dai, Xiongxin; Liblong, Aaron; Kramer-Tremblay, Sheila; Priest, Nicholas; Li, Chunsheng

2012-05-04

148

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

2011-02-16

149

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

150

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

151

Challenges of pixelated scintillators in medical X-ray imaging  

NASA Astrophysics Data System (ADS)

In current X-ray detectors, spatial resolution is limited by optical photon diffusion in the scintillator layer. A method to prevent photons from reaching neighboring pixels is the embedding of opaque walls within the scintillator. The realization of a pixelated scintillator faces, several challenges to obtain a good imaging performance, especially a high detective quantum efficiency (DQE). To maintain a high X-ray absorption, a high volume fill-factor is required. Losses of secondary light quanta have to be kept to a minimum to maintain an acceptable gain. Moreover, the signal per primary X-ray quanta should have a low variation with the depth of interaction to avoid a high secondary quantum noise (Swank-noise). Light scatter inside the scintillator causes both enhanced light loss and Swank-noise. For this work, a pixelated scintillator has been built from electrochemically etched silicon pore arrays, which are filled with cesium iodide (CsI:Tl). With a pixel pitch of 50 ?m, wall thicknesses of 6.5 ?m and pore depths of nearly 400 ?m are achieved. The modulation transfer function is 40% at 4 lp/mm and 10-20% at 8 lp/mm. The ability of the pores to transport light quanta from their origin to the photodiode is expressed in a light guiding efficiency, which is determined as 6.5% in the better cases. The maximal DQE(0) is 0.28, while the X-ray absorption with the given thickness and fill-factor is 0.57. The difference is explained by high Swank-noise due to optical scatter inside the CsI-filled pores, in agreement to Monte-Carlo simulations of the photon transport inside the pore array structure.

Simon, Matthias; Engel, Klaus-Jürgen; Menser, Bernd; Badel, Xavier; Linnros, Jan

2008-06-01

152

User's Guide to the Water-Analysis Screening Tool (WAST): A Tool for Assessing Available Water Resources in Relation to Aquatic-Resources Uses.  

National Technical Information Service (NTIS)

A water-analysis screening tool (WAST) was developed by the U.S. Geological Survey, in partnership with the Pennsylvania Department of Environmental Protection, to provide an initial screening of areas in the state where potential problems may exist relat...

J. L. Kiesler M. H. Stuckey

2008-01-01

153

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

154

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

155

Studies on scintillating fiber response  

NASA Astrophysics Data System (ADS)

Scintillating fibers of type Bicron BCF-12 with 2 × 2 mm2 cross section, up to 600 mm length, and PMMA cladding have been tested, in conjunction with the multi-channel photomultiplier Hamamatsu R 4760, with minimum ionizing electrons. The impact of cladding, extramural absorbers and/or wrapping on the light attenuation and photoelectron yield is studied in detail. Fibers have been circularly bent with radii of 171 mm and arranged in two layers to bundles forming granulated scintillator rings. Their performance in the EDDA experiment at COSY for detection of high energy protons revealed typically more than 9 (6) photoelectrons per fiber from bundles with (without) mirror on the rear side, guaranteeing detection efficiencies >99% and full compatibility with corresponding solid scintillator rings. The time resolution of 3.4 ns FWHM per fiber read out is essentially due to the R 4760.

Albers, D.; Bisplinghoff, J.; Bollmann, R.; Büßer, K.; Cloth, P.; Diehl, O.; Dohrmann, F.; Drüke, V.; Engelhardt, H. P.; Ernst, J.; Eversheim, P. D.; Filges, D.; Gasthuber, M.; Gebel, R.; Greiff, J.; Groß, A.; Groß-Hardt, R.; Heine, A.; Heider, S.; Hinterberger, F.; Igelbrink, M.; Jahn, R.; Jeske, M.; Langkau, R.; Lindlein, J.; Maier, R.; Maschuw, R.; Mayer-Kuckuk, T.; Mertler, G.; Metsch, B.; Mosel, F.; Müller, M.; Münstermann, M.; Paetz Gen. Schieck, H.; Petry, H. R.; Prasuhn, D.; Rohdjeß, H.; Rosendaal, D.; Roß, U.; von Rossen, P.; Scheid, H.; Schirm, N.; Schulz-Rojahn, M.; Schwandt, F.; Scobel, W.; Steeg, B.; Sterzenbach, G.; Trelle, H. J.; Wellinghausen, A.; Wiedmann, W.; Woller, K.; Ziegler, R.

1996-02-01

156

Nanophosphor composite scintillator with a liquid matrix  

DOEpatents

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

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

2010-03-16

157

Morphology of auroral zone radio wave scintillation  

Microsoft Academic Search

This paper describes the morphology of midnight sector and morning sector auroral zone scintillation observations made over a two-year period using the Wideband satelite, which is in a sun-synchronous, low-altitude orbit. No definitive seasonal variation was found. The nighttime data showed the highest scintillation ocurrence levels, but significant amounts of morning scintillation were observed. For the most part the scintillation

C. L. Rino; S. J. Matthews

1980-01-01

158

Composite scintillators for detection of ionizing radiation  

SciTech Connect

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

2010-12-28

159

Annular beam scintillations in strong turbulence.  

PubMed

A scintillation index formulation for annular beams in strong turbulence is developed that is also valid in moderate and weak turbulence. In our derivation, a modified Rytov solution is employed to obtain the small-scale and large-scale scintillation indices of annular beams by utilizing the amplitude spatial filtering of the atmospheric spectrum. Our solution yields only the on-axis scintillation index for the annular beam and correctly reduces to the existing strong turbulence results for the Gaussian beam--thus plane and spherical wave scintillation indices--and also correctly yields the existing weak turbulence annular beam scintillations. Compared to collimated Gaussian beam, plane, and spherical wave scintillations, collimated annular beams seem to be advantageous in the weak regime but lose this advantage in strongly turbulent atmosphere. It is observed that the contribution of annular beam scintillations comes mainly from the small-scale effects. At a fixed primary beam size, the scintillations of thinner collimated annular beams compared to thicker collimated annular beams are smaller in moderate turbulence but larger in strong turbulence; however, thinner annular beams of finite focal length have a smaller scintillation index than the thicker annular beams in strong turbulence. Decrease in the focal length decreases the annular beam scintillations in strong turbulence. Examining constant area annular beams, smaller primary sized annular structures have larger scintillations in moderate but smaller scintillations in strong turbulence. PMID:20686588

Gerçekcio?lu, Hamza; Baykal, Yahya; Nakibo?lu, Cem

2010-08-01

160

Damage to plastic scintillators by ionizing radiation  

Microsoft Academic Search

The intensity of the luminescence emission from plastic scintillators in which polystyrene is used as a base material is reduced as the doses of the a- and ß-radiation absorbed by the scintillator are increased. Furthermore, irradiation is characterized by a reduced transmission of the luminescent light of the plastic scintillators which, however, is not sufficient to explain quantitatively the reduction

I. M. Rosman; K. G. Zimmer

1957-01-01

161

Low-cost extruded plastic scintillator  

Microsoft Academic Search

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

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

2001-01-01

162

Principles and practice of plastic scintillator design  

Microsoft Academic Search

Plastic scintillators are used for ionizing radiation detection and measurement. A brief review is given of the standard plastic base materials, typical classes of fluorescent compounds, and some processing methods for producing plastic scintillators. The available parameters that determine the resultant scintillator performance are discussed.

S. W. Moser; W. F. Harder; C. R. Hurlbut; M. R. Kusner

1993-01-01

163

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

164

Magnetic fields and scintillator performance  

SciTech Connect

Experimental data have shown that the light output of a scintillator depends on the magnitude of the externally applied magnetic fields, and that this variation can affect the calorimeter calibration and possibly resolution. The goal of the measurements presented here is to study the light yield of scintillators in high magnetic fields in conditions that are similar to those anticipated for the LHC CMS detector. Two independent measurements were performed, the first at Fermilab and the second at the National High Magnetic Field Laboratory at Florida State University.

Green, D.; Ronzhin, A. [Fermi National Accelerator Lab., Batavia, IL (United States); Hagopian, V. [Florida State Univ., Tallahasse, FL (United States)

1995-06-01

165

Scintillation mechanisms in Ce3+ doped halide scintillators  

NASA Astrophysics Data System (ADS)

Last couple of years witnessed the development of various new Ce3+ doped halide scintillators (LaCl3, LaBr3, LuI3, Cs2LiYCl6, Cs2LiYBr6) that possess excellent gamma ray or thermal neutron detection properties. The scintillation pulse in LaBr3:Ce3+ is 20 times faster than in the most commonly used scintillator NaI:Tl. This, combined with a more then two times better energy resolution and higher gamma ray stopping power, makes it ideally suited for many different applications. In this work the scintillation properties and mechanisms of Ce3+ doped inorganic halide (Cl, Br, I) compounds are reviewed; especially the role of Vk centers and self trapped excitons (STEs) in the energy transfer from the ionization track to Ce3+ is treated. Aspects of the lifetime and thermal stability of the self trapped exciton, the migration speed of Vk centers and STEs, spectral overlap between STE emission and Ce3+ absorption, and the influence of the type of anion (Cl, Br, I) are addressed.

Dorenbos, Pieter

2005-01-01

166

Scintillating lustre induced by radial fins.  

PubMed

Radial lines of Ehrenstein patterns induce illusory scintillating lustre in gray disks inserted into the central gaps (scintillating-lustre effect). We report a novel variant of this illusion by replacing the radial lines with white and black radial fins. Both white and gray disks inserted into the central gaps were perceived as scintillating, if the ratio of the black/white fin width were balanced (ie, close to 1.0). Thus, the grayness of the central disk is not a prerequisite for the scintillation. However, the scintillation was drastically reduced when the ratio was imbalanced. Furthermore, the optimal ratio depended on the color of the center disks. PMID:23145270

Takahashi, Kohske; Fukuda, Haruaki; Watanabe, Katsumi; Ueda, Kazuhiro

2012-02-21

167

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

168

SNO+ Scintillator Purification and Assay  

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

169

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

170

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

171

Mechanoluminescence of plastic scintillation counters  

Microsoft Academic Search

Luminescence has been observed from the mechanical deformation of plastic scintillation materials. The light was recorded by means of a photomultiplier, and observed on a monitor by means of an intensified CCD camera. There is evidence for piezoluminescence as well as triboluminescence.

G. T. Reynolds; R. H. Austin

2000-01-01

172

Heavy Elements in Plastic Scintillators  

Microsoft Academic Search

The objective of this work is to study the possibilities of incorporating into plastic scintillators substantial quantities of heavy element compounds without the introduction of appreciable color or haze. Factors governing the quenching of the light output are considered, and a practical balance is struck between lowered pulse height and the quantity of heavy element introduced. The various components required

M. Jr. Hyman; J. J. Ryan

1958-01-01

173

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

174

Light scintillation in oceanic turbulence  

Microsoft Academic Search

The scintillation index of plane and spherical light waves as well as of a Gaussian beam, propagating in the clear-water weakly turbulent ocean, is revealed. The results are of utmost importance for underwater optical communications and sensing. An analysis of the threshold between the weak and strong regimes of oceanic turbulence is made, with the accent on the contribution from

O. Korotkova; N. Farwell; E. Shchepakina

2012-01-01

175

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

176

Spectra of strong scintillation caused by large-scale anisotropic stratospheric irregularities, in spacecraft-based observations  

NASA Astrophysics Data System (ADS)

Numerical methods are used to investigate one- and two-dimentional spectra of strong scintillation caused by atmospheric irregularities associated with the internal gravity waves. Calculations are based on the model of statistically uniform phase screen. The irregularities possess specific features: their spectra are anisotropic and they are much larger than the size of a Fresnel zone in the observation plane. The conditions are specified under which the theory of small perturbations can be applied to calculate weak-scintillation spectra. It is shown that large-scale part of the scintillation spectra can be appropriately described using the theory of perturbations even for strong scintillation, when the rms value of the relative intensity fluctuations ?0 , calculated with the perturbations method, equals 10. At the same time, the perturbations method is not applicable for the description of the small-scale portion of scintillation spectra even at ?0 >0.3. It was found that the product of 1-D spectral density and a wave number has a "plateau" interval. The level of this plateau depends only on the parameter ?0 , provided that this parameter is smaller than one-third of the squared anisotropy coefficient. Within the interval of large wave numbers, the maximum point of the scintillation spectra is formed, with the value of 0.242. The conditions are formulated for small-scale part of the spectrum to become normal; under these conditions, the scintillation spectrum is equal to that of the squared coherence function on the phase screen.

Fedorova, O. V.; Marakasov, D. A.; Vorob'ev, V. V.

2006-11-01

177

Radioluminescence dosimetry by scintillating fiber optics: the open challenges  

NASA Astrophysics Data System (ADS)

In the last decade, the interest in scintillating fiber optics for ionizing radiation monitoring is constantly increasing. Among the fields of possible applications of these sensors, radiation therapy represents a driving force for the research and development of new devices. In fact, the small dimensions of fiber optics based detectors, together with their realtime response, make these systems extremely promising both in quality assurance measurements of intensity modulated radiotherapy beams, and in in-vivo dosimetry. On the other hand, two specific aspects might represent limiting factors: (i) the "stem effect", that is the spurious luminescence originating as a consequence of the irradiation of the light guide, and (ii) the "memory effect", that is the radioluminescence sensitivity increase during prolonged exposition to ionizing radiation, typical of many scintillating materials. These two issues, representing the main challenges to face for the effective use of scintillating fiber as dosimeters in radiotherapy, were studied considering amorphous silica matrices prepared by sol-gel method and doped with europium. The origin of the stem effect was investigated by means of spectral measurements of the doped fibers irradiated with Xrays and electrons of different energies, field sizes and orientations. New approaches for removing the stem effect on the basis of the radioluminescent spectral analysis are presented and discussed. Furthermore, the causes and phenomenology of the memory effect are described, considering also the effect of dose accumulation with different dose rates and energies of ionizing radiation.

Veronese, Ivan; Cantone, Marie Claire; Chiodini, Norberto; De Mattia, Cristina; Fasoli, Mauro; Mones, Eleonora; Vedda, Anna

2013-09-01

178

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

179

Irradiance scintillation for laser beam propagation in turbulent atmosphere  

Microsoft Academic Search

A new heuristic optical scintillation model developed recently is viewed and it is an available method in investigation on laser beams propagation in turbulent atmosphere. The irradiance scintillation is treated as a modulation of small scale scintillation by large scale scintillation as laser beams propagation in turbulent atmosphere, the irradiance scintillation is investigated for uplink propagation at various receiving heights

Xiwen Qiang; Jingru Liu; Deyan Cheng; Shengyi Xiong; Xisheng Ye

2002-01-01

180

A helical scintillating fiber hodoscope  

NASA Astrophysics Data System (ADS)

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

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

1999-07-01

181

Detecting scintillations in liquid helium  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

182

Silicon photomultipliers for scintillating trackers  

Microsoft Academic Search

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

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

183

Scintillation Forecasting Using NPOESS Data  

NASA Astrophysics Data System (ADS)

We have conducted a theoretical study of the use of NPOESS data for the forecasting of equatorial radio scintillation using knowledge of the equatorial Appleton anomaly, e.g., the peak-to-valley ratio of TEC (Total Electron Content) between the anomaly crests and the magnetic equator. The peak-to-valley ratio can be obtained from the UV (ultraviolet) imagery of the anomaly region that will be provided by the NPOESS sensors. The post-sunset enhancement of the upward drift velocity of the equatorial plasma has been shown, both theoretically and observationally, to be an important determinant of both the onset of scintillation and the strength of the anomaly. The technical approach is to run PBMOD, the AFRL low-latitude ionosphere model, with a range of post-sunset vertical drift velocities to determine the quantitative relationship between the peak-to-valley ratio and the maximum value of the pot-sunset upward drift velocity of equatorial plasma. Once the relationship is validated, it will be used to estimate the maximum value of the drift velocity from the peak-to-valley ratio, which is derived from the UV imagery data provided by NPOESS-like sensor, such as GUVI on TIMED satellite. The drift velocity will then be used in PBMOD to simulate the formation and evolution of equatorial plasma `bubbles' and calculate the distribution of the amplitude scintillation index S4. Results of the study will be discussed.

Basu, B.; Retterer, J.; Demajistre, R.; de La Beaujardiere, O.; Scro, K.

2005-12-01

184

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

185

Weak-scintillation light yield determination  

SciTech Connect

The pulse-height distribution produced by weak scintillations is simulated as a Poisson distribution if the mean number of photoelectrons collected at the first dynode is of the order of one. This method enables one to determine the scintillation yield also when the photomultiplier does not show a peak in the single-electron pulses. Scintillation yields have been determined for some aqueous solutions of sodium salicylate and for aromatic solvents (benzene, toluene, and xylene) on internal irradiation by ..cap alpha.. particles.

Mandzhukov, I.G.; Mandzhukova, B.V.

1987-12-01

186

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

187

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

188

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

189

HiLat scintillation measurements at Spitsbergen  

NASA Astrophysics Data System (ADS)

Since October 1984, the amplitudes of 137 and 413 MHz HiLat radio beacon transmissions have been recorded at the Polish Polar Station at Hornsund, Spitsbergen (Svalbard) (77.00 deg N, 15.55 deg E). Graphs are presented of the magnetic local time dependence of the percentage occurrence of scintillation with SI greater than 0 and 0.3. For Kp = 3, scintillation occurrence is at a minimum at noon; for Kp less than 3, scintillation is at a maximum in the dawn and dusk sectors. The scintillation intensity is found to rapidly decrease on the equatorward side of the auroral oval.

Wernik, A. W.; Gola, M.

190

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

191

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)

1996-06-01

192

Scintillation properties of lead sulfate  

NASA Astrophysics Data System (ADS)

We report on the scintillation properties of lead sulfate (PbSO4), a scintillator that show 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(exp 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 percent pure PbSO4 crystals at room temperature excited by 511 keV annihilation photons, the fluorescence decay lifetime contains significant fast components having 1.8 ns (5 percent) and 19 ns (36 percent) decay times, but with longer components having 95 ns (36 percent) and 425 ns (23 percent) 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 from 3,200 photons/MeV at +45 C to 4,900 photons/MeV at room temperature (+25 C) and 68,500 photons/MeV at -145 C. In an imperfect, 3 mm cube of a naturally occurring mineral form of PbSO4 (anglesite) at room temperature, a 511 keV photopeak is seen with a total light output of 60 percent 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.

Moses, W. W.; Derenzo, S. E.; Shlichta, P. J.

1991-11-01

193

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

194

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

195

Radiation damage effects on liquid scintillating fibers  

Microsoft Academic Search

The effects of radiation on liquid scintillating fibers composed of borosilicate glass (Pyrex) tubing in combination with a high refractive index liquid scintillator are investigated. The fiber components (tubes, liquids and liquids in tubes), were irradiated in a nuclear reactor with doses exceeding 100 megarads. It was found that the discoloration of the glass tubing does not degrade the optical

Mei Gui; F. R. Huson; Tina Ostrovsky; Dan Reese; Dan Suson; J. T. White

1993-01-01

196

Glass-liquid scintillating fibers for calorimetry  

Microsoft Academic Search

An interesting calorimeter technology for possible use in high radiation and high rate applications is the liquid scintillating fiber spaghetti calorimeter. Once a leading candidate for use at the SSC, a considerable amount of research was done to find liquid scintillating fibers with properties (light output, attenuation length and radiation resistance) satisfying the requirements for use in this application. In

M. Gui; F. R. Huson; J. T. White; D. Suson

1996-01-01

197

Behaviour of HILAT scintillation over Spitsbergen  

Microsoft Academic Search

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

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

1992-01-01

198

CONICAL PLASTIC SCINTILLATORS SHOW TOTAL GAMMA ABSORPTION  

Microsoft Academic Search

Total photon absorption, at least with low energy gamma and x rays, ; was observed in plastic scintillators. The best results were obtained with lead-; loaded, conically-shaped scintillators surrounded by aluminuru oxide as a ; reflector. Low energy photons gave better absorption curves even poorer ; resolution than the higher energy photons. The best stintillation size for total ; absorption

G. J. Hine; J. A. Cardarelli

1960-01-01

199

Polyimide-based scintillating thin films  

Microsoft Academic Search

The production procedure and the scintillation characteristics of thin polyimide films containing rhodamine B are reported. Fluorinated polyimide has been chosen as host matrix for its well known radiation hardness, in order to improve the lifetime of detector systems based on plastic thin film scintillators, 6FDA (4,4'-hertafluoroisopropylidene diphthalic anhydride) and DAB (diaminobenzophenone) have been used as polyimide precursor monomers. The

A. Quaranta; S. Carturan; G. Maggioni; P. M. Milazzo; U. Abbondanno; G. Della Mea; F. Gramegna; U. Pieri

2001-01-01

200

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

201

Ionospheric scintillation effects on UHF satellite communications  

Microsoft Academic Search

Naturally induced high altitude ionization will cause signal scintillation effects that are of great importance to the design and deployment of military satellite systems employing frequencies below 1 GHz. The scintillation will result in Rician or Rayleigh signal fading with finite signal decorrelation time and limited coherent bandwidth of the transmission channel

P. A. Kullstam; M. J. Keskinen

2000-01-01

202

Scintillation Decay Times of Organic Crystals  

Microsoft Academic Search

A new experimental technique is described for measuring scintillation decay times in the millimicrosecond region. The method developed uses the fact that a pulsed current, as delivered by the photomultiplier scintillation counter produces a far greater power dissipation in a resistive load than does the same mean steady current. By measuring the power dissipated the pulse duration, and hence the

G T Wright

1956-01-01

203

Liquid scintillation counting in nuclear medicine  

Microsoft Academic Search

Many of the radionuclides used in nuclear medicine can be measured by ; liquid scintillation (LS) counting, and the technique is the only practical ; approach to counting low-energy BETA emissions. The capabilities of LS ; counting and of some precautions that should be observed are reviewed. Because ; most scintillation solvents will tolerate only minimal amounts of aqueous samples

Bransome; E. D. Jr

1973-01-01

204

Scintillation Counting in Experiments on Parity Conservation  

Microsoft Academic Search

The scintillation counter has played a key role in many of the recent experiments pertaining to the conservation of parity and other symmetry principles in weak interactions. Although in many instances the development of the techniques of scintillation counting, per se, has been limited, the applications to which these techniques have been put are sufficiently novel to warrant a general

R. W. Hayward; D. D. Hoppes

1958-01-01

205

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

PubMed

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

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

2005-10-01

206

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

207

The improved scintillation crystal lead tungstate scintillation for PET  

NASA Astrophysics Data System (ADS)

As a valuable material for the detecting of ?-ray, PbWO4 and BaF2:PbWO4 crystals were grown by a novel multi-crucible temperature gradient system developed by ourselves. Utilizing a topical partial heating method, this system can form a topical partial high temperature in its hearth. Thus this system could melt raw materials in step by step as requirement. The advantage of this method is that there would be solid obstruct left on the melt in the procedure of the crystal growing up. The left obstruct could prevent the volatilization of the component in the melt. Hence it is helpful for the composition homogenization in the crystal. The system also offers a sustaining device for multi-crucibles and thus it can grow many crystals simultaneity. The optical properties and scintillation properties of the crystals were studied. The results reveal that the ions doping improves the scintillation properties of the crystal. The transmittance spectra show that the transmittance of BaF2:PbWO4 crystals are better than that of PbWO4 crystals. For the PbWO4 crystals, their absorption edge is at 325nm, and their maximum transmittance is 68%. For the BaF2:PbWO4 crystals, their absorption edge is at 325nm and their maximum transmittance is upto76%. The X-ray excited luminescence spectra shows that the luminescence peak is at 420nm for the samples of PbWO4 crystal while the peak is at 430nm for the samples of BaF2:PbWO4 crystal respectively. The luminescence intensity of the samples of BaF2:PbWO4 crystal is about two times than that of PbWO4 crystal. And their peak shape is different for the two kind of crystal. The light yield of BaF2:PbWO4 crystals is about 2.9 times than that of PbWO4 crystal Analyzing these scintillation properties, we find that the VPb 3+ and VO- defects do harm for the optical properties of the crystal. Ions doping method could reduce the defect concentration and improving its illumination performance of the crystal. Specially, the doped F- ions in O2- site can induce the aberrance of the [WO4]2- tetrahedron and form [WO3F]- tetrahedron which has more active blue light yield, thus improve the light yield of the crystal. The improved light yield of BaF2:PbWO4 crystals is valuable for the medical diagnosing instrument PET and CT with high resolving power

Wan, Youbao; Wu, Rurong; Xiao, Linrong; Zhang, Jianxin; Yang, Peizhi; Yan, Hui

2009-07-01

208

Design Rules for Ce-activated scintillating radiation detection materials: Compromises between Luminosity and stopping power  

SciTech Connect

In recent years, the scintillation properties of many specific cerium-doped scintillators (such as LSO and BaBr3) have been extensively studied. This paper presents new development methods for property-screening design rules ,using structure-property relationships for two fundamental target detector properties--luminosity and stopping power. The first and most evident goal in developing screening models of luminosity and stopping power is to obtain new candidate cerium scintillating materials. However, a second and more strategic goal is to extract design rules, which define the structural limitations on materials consistent with desirable detector properties. The design rules are based on our capability to predict the luminescence and stopping power of a material from a set of structural descriptors. These models are generated using statistical multiple linear regression techniques over a large set of 24 descriptors. We find that within a set of ten cerium-doped scintillator materials that we can quantitatively predict luminosity and stopping power with a correlation coefficient of ~0.99 based on 6 of the 24 descriptors. Furthermore, we show that in this circumstance the luminosity and stopping power are nominally related and only share one common descriptor in the developed models. In particular luminosity depends largely on matrix valence electron properties and their coupling to activator sites—properties that do not require high atomic masses per se, a requirement for high stopping power.

Webb-Robertson, Bobbie-Jo M.; Ferris, Kim F.; Jones, Dumont M.

2008-06-01

209

Guided-mode launching in a slab waveguide by way of diffraction at the edge of a conducting screen residing on one surface of the slab  

NASA Astrophysics Data System (ADS)

The behavior of electromagnetic fields in the presence of a dielectric waveguide or in the presence of a perfectly electrically conducting (p.e.c.) half plane constitute two general classes of problems in the study of electromagnetics. In this report we consider the case of a p.e.c. half plane residing on one surface of a dielectric slab waveguide in a homogeneous, lossless medium. A transverse magnetic plane wave impinges on the waveguide from the side of the slab on which the half plane resides. The boundary conditions for the electric field tangential to the half plane are cast in a form amenable to a Wiener-Hopf solution, from which the scattered electric field in the interior of the slab waveguide is obtained in terms of a radiation integral. This integral is evaluated using the method of steepest descents, and the resulting electric field is separated into a geometrical optics contribution, a contribution from diffraction at the edge of the half plane, a contribution from refraction by the waveguide, and guided-mode contributions.

Farris, T. H.; Pearson, L. W.

1985-03-01

210

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

Microsoft Academic Search

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

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

2011-01-01

211

Application of refractive scintillation theory to radio transmission through the ionosphere and the solar wind, and to reflection from a rough ocean  

Microsoft Academic Search

The theory of diffractive scattering by small-scale irregularities is combined with the results of Booker and MajidiAhi (1981) concerning refractive scattering by large-scale irregularities in a phase-changing screen, in a study of three intensity scintillation phenomena: (1) the reflection of radio and optical waves from an ocean surface disturbed by a spectrum of water waves; (2) the scintillation of VHF,

H. G. Booker

1981-01-01

212

Scintillation Breakdowns and Reliability of Solid Tantalum Capacitors  

Microsoft Academic Search

Scintillations are momentarily local breakdowns in tantalum capacitors, which are often considered as nuisances rather than failures. However, this paper shows that scintillations are damaging for more than 30% of part types and up to 100% for some lots. Scintillations can be observed after many hours of operation, and the probability of repeat scintillations is higher than of the initial

Alexander Teverovsky

2009-01-01

213

INCREASING THE LIGHT COLLECTION EFFICIENCY OF SCINTILLATION COUNTERS  

Microsoft Academic Search

A systematic study was made of methods of increasing the light ; collection efficiency of scintillation counters. Various reflectors, surface ; treatment of the scintillator, relative geometries of scintillator and ; photodiode, and light pipes were tried, using plastic scintillator cubes. 3 and ; 6 in. on a side, and right circular cylinders, 3 in. in dia. by 3 in.

C. M. Ankenbrandt; E. M. Lent

1962-01-01

214

Increasing the Light Collection Efficiency of Scintillation Counters  

Microsoft Academic Search

A systematic study was made of methods of increasing the light collection efficiency of scintillation counters. Various reflectors, surface treatment of the scintillator, relative geometries of scintillator and photodiode, and light pipes were tried, using plastic scintillator cubes, 3 and 6 in. on a side, and right circular cylinders, 3 in. in diameter by 3 in. in length and 6

C. M. Ankenbrandt; E. M. Lent

1963-01-01

215

Increasing the Light Collection Efficiency of Scintillation Counters  

Microsoft Academic Search

A systematic study was made of methods of increasing the light ; collection efficiency of scintillation counters. Various reflectors, surface ; treatment of the scintillator, relative geometries of scintillator and ; photodiode, and light pipes were tried, using plastic scintillator cubes, 3 and 6 ; in. on a side, and right circular cylinders, 3 in. in diameter by 3 in.

C. M. Ankenbrandt; E. M. Lent

1963-01-01

216

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

217

Spectra of strong scintillation caused by large-scale anisotropic stratospheric irregularities, in spacecraft-based observations  

Microsoft Academic Search

Numerical methods are used to investigate one- and two-dimentional spectra of strong scintillation caused by atmospheric irregularities associated with the internal gravity waves. Calculations are based on the model of statistically uniform phase screen. The irregularities possess specific features: their spectra are anisotropic and they are much larger than the size of a Fresnel zone in the observation plane. The

O. V. Fedorova; D. A. Marakasov; V. V. Vorob'ev

2006-01-01

218

Pulse shaping analysis with LAB-based liquid scintillators  

NASA Astrophysics Data System (ADS)

We report on a pulse shaping analysis for alpha-beta discrimination using a linear alkylbenzene (LAB)-based liquid scintillator developed for reactor neutrino experiments. The scintillation properties are measured with an internal alpha source diluted in the same scintillator and an external gamma source. The comparison of the fast and the slow parts in the signal waveforms provide clear separations of alpha and gamma events in the liquid scintillator. The discrimination power is compared between the LAB-based liquid scintillator and other commercially available liquid scintillators. The potential use of this scintillator when loaded with 6Li is discussed with regard to neutron measurements.

Lee, J. S.; Kim, Y. H.; Lee, K. B.; Lee, M. K.; Ma, K. J.; Jeon, E. J.; Kim, J. Y.; Kim, N. Y.; Kim, Y. D.; Lee, J. Y.

2012-02-01

219

On Rapid Interstellar Scintillation of Quasars: PKS 1257-326 Revisited  

NASA Astrophysics Data System (ADS)

The line of sight towards the compact, radio loud quasar PKS 1257-326 passes through a patch of scattering plasma in the local Galactic ISM that causes large and rapid, intra-hour variations in the received flux density at centimetre wavelengths. This rapid interstellar scintillation (SS) has been occurring for at least 15 years, implying that the scattering ``screen'' is at least 100 AU in physical extent. Through observations of the ISS we have measured microarcsecond-scale ``core shifts'' in PKS 1257-326, corresponding to changing opacity during an intrinsic outburst. Recent analysis of VLA data of a sample of 128 quasars found 6 sources scintillating with a characteristic time-scale of < 2 hours, suggesting that nearby scattering screens in the ISM may have a covering fraction of a few percent. That is an important consideration for proposed surveys of the transient and variable radio sky.

Bignall, Hayley E.; Hodgson, Jeffrey A.

2012-04-01

220

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

221

Scintillation of rare earth doped fluoride nanoparticles  

SciTech Connect

The scintillation response of rare earth (RE) doped core/undoped (multi-)shell fluoride nanoparticles was investigated under x-ray and alpha particle irradiation. A significant enhancement of the scintillation response was observed with increasing shells due: (i) to the passivation of surface quenching defects together with the activation of the REs on the surface of the core nanoparticle after the growth of a shell, and (ii) to the increase of the volume of the nanoparticles. These results are expected to reflect a general aspect of the scintillation process in nanoparticles, and to impact radiation sensing technologies that make use of nanoparticles.

Jacobsohn, L. G.; McPherson, C. L.; Sprinkle, K. B.; Ballato, J. [Center for Optical Materials Science and Engineering Technologies (COMSET), and School of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States); Yukihara, E. G. [Physics Department, Oklahoma State University, Stillwater, Oklahoma 74078-3072 (United States); DeVol, T. A. [Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, South Carolina 29634-0905 (United States)

2011-09-12

222

Scintillation Light, Ionization Yield and Scintillation Decay Times in High Pressure Xenon and Xenon Methane  

Microsoft Academic Search

Scintillation light, ionization yield and scintillation decay times have been measured in xenon and in its mixture with a 0.05% concentration of methane as a function of the reduced electric field (E\\/N)-the ratio of the electric field strength to the number density of gas-at a pressure of 21 atm. The measurements of scintillation decay times in the xenon-methane mixture have

K. N. Pushkin; D. Y. Akimov; A. A. Burenkov; V. V. Dmitrenko; A. G. Kovalenko; V. N. Lebedenko; I. S. Kuznetsov; V. N. Stekhanov; C. Tezuka; S. E. Ulin; Z. M. Uteshev; K. F. Vlasik

2007-01-01

223

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

Microsoft Academic Search

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

Koichi Nittoh; Takeshi Takahara; Tadashi Yoshida; Toshiyuki Tamura

1999-01-01

224

Image transfer characteristics of europium activated scintillators for medical imaging applications  

Microsoft Academic Search

Image transfer characteristics (MTF, DQE) of Y2O2 S:Eu, Y2O3:Eu, and YVO4:Eu image receptors were evaluated. These materials were used in the form of laboratory prepared screens. MTF was experimentally determined by the square wave response method and theoretically evaluated by a diffusion equation model. DQE was calculated using experimentally determined optical data of the scintillators. Light spectra were measured and

D. Cavouras; I. Kandarakis; I. Theocharakis; G. Panayiotakis; C. Nomicos

1996-01-01

225

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

226

Ball valve safety screen  

SciTech Connect

A device for preventing unwanted objects from entering the ball assembly of a float collar or float shoe and otherwise damaging or plugging the valve mechanism therein is disclosed. The device comprises a screen constructed of expanded metal and rigidly affixed to the interior of the float collar or float shoe above the ball valve assembly. The screen portion is either mounted to the interior surface of the float collar sleeve by an annular structural member or mounted to a structural band which is partially embedded in the concrete portion of the float collar or casing guide shoe.

Bolding, B.H.

1981-09-01

227

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

228

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

PubMed

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

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

2011-11-28

229

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

230

Thermal Quenching of Some Liquid Scintillators.  

National Technical Information Service (NTIS)

Heating organic liquid scintillator solutions has proven to be an efficient way to improve the time response in some cases. Higher temperatures increase the rates of diffusion-controlled energy transfer processes in dilute solutions and in solutions with ...

S. S. Lutz C. B. Ashford J. M. Flournoy L. A. Franks P. B. Lyons

1983-01-01

231

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

232

Coping with Plastic Scintillators in Nuclear Safeguards.  

National Technical Information Service (NTIS)

Plastic scintillators offer several advantages for nuclear safeguards research and technology to those who design, assemble, encapsulate, and calibrate detectors from raw materials that are commercially available. These large, inexpensive detectors have g...

P. E. Fehlau G. S. Brunson

1982-01-01

233

Scintillation Breakdowns in Chip Tantalum Capacitors.  

National Technical Information Service (NTIS)

Scintillations in solid tantalum capacitors are momentarily local breakdowns terminated by a self-healing or conversion to a high-resistive state of the manganese oxide cathode. This conversion effectively caps the defective area of the tantalum pentoxide...

A. Teverovsky

2008-01-01

234

Scintillation Selector for Low Energy Charged Particles.  

National Technical Information Service (NTIS)

A proportional multiplier is coupled with a scintillation counting device in appropriate combination to detect and count low-energy charged subatomic particles, such as beta particles. The proportional multiplier portion of the combination imposes across ...

K. F. Sinclair

1966-01-01

235

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

236

Neutron scintillators using wavelength shifting fibers  

Microsoft Academic Search

A proposed design for an optically-based, one-dimension scintillation detector to replace the gas-filled position-sensitive proportional counter currently used for a wide-angle neutron detector (WAND) at the high-Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) is presented. The scintillator, consisting of a mixture of ⁶LiF and ZnS(Ag) powders in an epoxy binder, is coupled to an array of

D. P. Hutchinson; V. C. Miller; J. A. Ramsey

1995-01-01

237

Factors determining radiation stability of plastic scintillators  

Microsoft Academic Search

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

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

1995-01-01

238

Space Radiation Effects in Scintillating Material  

Microsoft Academic Search

A series of tests was conducted in a space environment chamber to determine experimentally the space radiation effects in ZnCdS, CaWO4 and CsI. The scintillating materials were exposed to electron and proton beams of varying energy and flux to determine techniques for reducing space radiation induced light emission to a minimum. The objective was to determine whether scintillating materials could

D. B. Ebeoglu; P. J. Doody; C. Lowman; M. Bender; J. F. Long

1970-01-01

239

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

240

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

241

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

242

Specific luminescence studies in plastic scintillators  

Microsoft Academic Search

Using a thin-film scintillator detector direct measurements of relative specific luminescence (DeltaL Deltax) and luminescence efficiency (DeltaL DeltaE) values have been obtained for an organic scintillator exposed to transiting light and heavy ions. These experimentally obtained luminescence data are presented as a function of ion energy, velocity, and stopping power for a wide variety of transiting ions (Z=1,2,8,17,18,35,53). The data

L. Muga; G. Griffith

1974-01-01

243

Factors determining radiation stability of plastic scintillators  

Microsoft Academic Search

Polystyrene (PS) and polyvinylxylene (PVX) are the base materials for plastic scintillators. u.v.-Vis spectrophotometry, luminescence and ESR spectroscopy were performed on irradiated samples of PS and PVX with the p-terphenyl (TP) as the primary luminophore and 1,4-di-2(5-phenyloxazolyl-1,3)benzene (POPOP) as the secondary one. Dependence of the radioluminescence intensity of the scintillators on the concentration of the macroradicals formed by irradiation was

N. N. Barashkov; O. A. Gunder; N. I. Voronkina; V. K. Milinchuk

1996-01-01

244

A new radiation-resistant plastic scintillator  

SciTech Connect

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 /sup 60/Co gamma radiation for doses of 10 megarad.

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

1989-02-01

245

GNSS station characterisation for ionospheric scintillation applications  

NASA Astrophysics Data System (ADS)

Ionospheric scintillations are fluctuations in the phase and amplitude of the signals from GNSS (Global Navigation Satellite Systems) occurring when they cross regions of electron density irregularities in the ionosphere. Such disturbances can cause serious degradation of several aspects of GNSS system performance, including integrity, accuracy and availability. The two indices adopted worldwide to characterise ionospheric scintillations are: the amplitude scintillation index, S4, which is the standard deviation of the received power normalised by its mean value, and the phase scintillation index, ??, which is the standard deviation of the de-trended carrier phase. Collaborative work between NGI and INGV supports a permanent network of GISTM (GPS Ionospheric Scintillation and TEC Monitor) receivers that covers a wide range of latitudes in the northern European sector. Data from this network has contributed significantly to several papers during the past few years (see e.g. De Franceschi et al., 2008; Aquino et al., 2009; Spogli et al., 2009, 2010; Alfonsi et al., 2011). In these investigations multipath effects and noise that contaminate the scintillation measurements are largely filtered by applying an elevation angle threshold. A deeper analysis of the data quality and the development of a more complex filtering technique can improve the results obtained so far. The structures in the environment of each receiver in the network which contaminate scintillation measurements should be identified in order to improve the quality of the scintillation and TEC data by removing error sources due to the local environment. The analysis in this paper considers a data set characterised by quiet ionospheric conditions of the mid-latitude station located in Nottingham (UK), followed by a case study of the severe geomagnetic storm, which occurred in late 2003, known generally as the "Halloween Storm".

Romano, Vincenzo; Spogli, Luca; Aquino, Marcio; Dodson, Alan; Hancock, Craig; Forte, Biagio

2013-10-01

246

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

PubMed Central

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 Iopt), 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 Iopt and zero-frequency DQE for segmented CsI:Tl and BGO detectors at different thicknesses and element-to-element pitches. For these detectors, Iopt 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 Iopt 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 ?29% and 42%, corresponding to improvement by factors of ?29 and 42, respectively, compared to that of conventional MV AMFPIs.

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

2009-01-01

247

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

PubMed

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(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(opt) and zero-frequency DQE for segmented CsI:Tl and BGO detectors at different thicknesses and element-to-element pitches. For these detectors, I(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(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 approximately 29% and 42%, corresponding to improvement by factors of approximately 29 and 42, respectively, compared to that of conventional MV AMFPIs. PMID:19673222

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

2009-07-01

248

Ionospheric scintillation effects on single frequency GPS  

NASA Astrophysics Data System (ADS)

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 amplitude scintillation data spanning 7 years from Ascension Island, U.K.; Ancon, Peru; and Antofagasta, Chile in the Atlantic/American longitudinal sector as well as data from Parepare, Indonesia; Marak Parak, Malaysia; Pontianak, Indonesia; Guam; and Diego Garcia, U.K. in the Pacific longitudinal sector. From these data, we calculate percent probability of occurrence of scintillation at various intensities described by the S4 index. Additionally, we determine Dilution of Precision at 1 min resolution. We examine diurnal, seasonal, and solar cycle characteristics and make spatial comparisons. In general, activity was greatest during the equinoxes and solar maximum, although scintillation at Antofagasta, Chile was higher during 1998 rather than at solar maximum.

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

2008-04-01

249

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

250

High-resolution tracking using large capillary bundles filled with liquid scintillator  

NASA Astrophysics Data System (ADS)

We have developed large high-resolution tracking detectors based on glass capillaries filled with organic liquid scintillator of high refractive index. These liquid-core scintillating optical fibres act simultaneously as detectors of charged particles and as image guides. Track images projected onto the readout end of a capillary bundle are visualized by an optoelectronic chain consisting of a set of image-intensifier tubes followed by a photosensitive CCD or by an EBCCD camera. Two prototype detectors, each composed of ~106 capillaries with 20-25?m diameter and 0.9-1.8 m length, have been tested, and a spatial resolution of the order of 20-40?m has been attained. A high scintillation efficiency and a large light-attenuation length, in excess of 3 m, was achieved through special purification of the liquid scintillator. Along the tracks of minimum-ionizing particles, the hit densities obtained were ~8hits/mm at the readout window, and ~3hits/mm at ~1m away. The level of radiation resistance of the prototype detectors is at least an order of magnitude higher than that of other tracking devices of comparable performance.

Annis, P.; Bay, A.; Benussi, L.; Bruski, N.; Buontempo, S.; Currat, C.; D'Ambrosio, N.; van Dantzig, R.; Dupraz, J.; Ereditato, A.; Fabre, J. P.; Fanti, V.; Feyt, J.; Frekers, D.; Frenkel, A.; Galeazzi, F.; Garufi, F.; Goldberg, J.; Golovkin, S. V.; Gorin, A. M.; Grégoire, G.; Harrison, K.; Hoepfner, K.; Holtz, K.; Konijn, J.; Kozarenko, E. N.; Kreslo, I. E.; Kushnirenko, A. E.; Liberti, B.; Martellotti, G.; Medvedkov, A. M.; Michel, L.; Migliozzi, P.; Mommaert, C.; Mondardini, M. R.; Panman, J.; Penso, G.; Petukhov, Y. P.; Rondeshagen, D.; Siegmund, W. P.; Tyukov, V.; Beek, G. V.; Vasil'chenko, V. G.; Vilain, P.; Visschers, J. L.; Wilquet, G.; Winter, K.; Wolff, T.; Wörtche, H. J.; Wong, H.; Zimyn, K. V.

2000-07-01

251

Cancer screening  

Microsoft Academic Search

Cancer screening is a complicated science. Each screening intervention must be carefully assessed before it is widely implemented. A screening test can falsely appear useful as it finds disease at an early stage and leads to intervention and cure. Such a test can be harmful to the population screened if it commonly finds disease that fulfills the pathologic criteria of

Otis W Brawley

2004-01-01

252

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

SciTech Connect

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

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

1984-01-01

253

Guided imagery  

Microsoft Academic Search

PURPOSE: Guided imagery uses the power of thought to influence psychologic and physiologic states. Some studies have shown that guided imagery can decrease anxiety, analgesic requirements, and length of stay for surgical patients. This study was designed to determine whether guided imagery in the perioperative period could improve the outcome of colorectal surgery patients. METHODS: We conducted a prospective, randomized

Diane L. Tusek; James M. Church; Scott A. Strong; Jeffrey A. Grass; Victor W. Fazio

1997-01-01

254

Atomistic models for scintillator discovery.  

SciTech Connect

A2BLnX6 elpasolites (A, B: alkali; Ln: lanthanide; X: halogen), LaBr3 lanthanum bromide, and AX alkali halides are three classes of the ionic compound crystals being explored for {gamma}-ray detection applications. Elpasolites are attractive because they can be optimized from combinations of four different elements. One design goal is to create cubic crystals that have isotropic optical properties and can be grown into large crystals at lower costs. Unfortunately, many elpasolites do not have cubic crystals and the experimental trial-and-error approach to find the cubic elpasolites has been prolonged and inefficient. LaBr3 is attractive due to its established good scintillation properties. The problem is that this brittle material is not only prone to fracture during services, but also difficult to grow into large crystals resulting in high production cost. Unfortunately, it is not always clear how to strengthen LaBr3 due to the lack of understanding of its fracture mechanisms. The problem with alkali halides is that their properties decay rapidly over time especially under harsh environment. Here we describe our recent progress on the development of atomistic models that may begin to enable the prediction of crystal structures and the study of fracture mechanisms of multi-element compounds.

Doty, F. Patrick; Yang, Pin (Sandia National Laboratories, Albuquerque, NM); Zhou, Xiao Wang

2010-07-01

255

Imaging performance and light emission efficiency of Lu 2 SiO 5 :Ce (LSO:Ce) powder scintillator under X-ray mammographic conditions  

Microsoft Academic Search

The aim of the present study was to measure the imaging transfer characteristics and the luminescence efficiency (XLE) of\\u000a a Lu2SiO5:Ce (LSO:Ce) powder scintillator for use in X-ray mammography detectors. An LSO:Ce powder scintillating screen, with a coating\\u000a thickness of 25 mg\\/cm2, was prepared in our laboratory. The imaging performance of the screen was assessed by experimental determination of the\\u000a modulation

C. Michail; A. Toutountzis; S. David; N. Kalyvas; I. Valais; I. Kandarakis; G. S. Panayiotakis

2009-01-01

256

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

SciTech Connect

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

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

1996-08-01

257

Chemical compatibility screening test results  

SciTech Connect

A program for evaluating packaging components that may be used in transporting mixed-waste forms has been developed and the first phase has been completed. This effort involved the screening of ten plastic materials in four simulant mixed-waste types. These plastics were butadiene-acrylonitrile copolymer rubber, cross-linked polyethylene (XLPE), epichlorohydrin rubber, ethylene-propylene rubber (EPDM), fluorocarbon (Viton or Kel-F), polytetrafluoroethylene, high-density polyethylene (HDPE), isobutylene-isoprene copolymer rubber (butyl), polypropylene, and styrene-butadiene rubber (SBR). The selected simulant mixed wastes were (1) an aqueous alkaline mixture of sodium nitrate and sodium nitrite; (2) a chlorinated hydrocarbon mixture; (3) a simulant liquid scintillation fluid; and (4) a mixture of ketones. The testing protocol involved exposing the respective materials to 286,000 rads of gamma radiation followed by 14-day exposures to the waste types at 60{degrees}C. The seal materials were tested using vapor transport rate (VTR) measurements while the liner materials were tested using specific gravity as a metric. For these tests, a screening criterion of 0.9 g/hr/m{sup 2} for VTR and a specific gravity change of 10% was used. Based on this work, it was concluded that while all seal materials passed exposure to the aqueous simulant mixed waste, EPDM and SBR had the lowest VTRs. In the chlorinated hydrocarbon simulant mixed waste, only Viton passed the screening tests. In both the simulant scintillation fluid mixed waste and the ketone mixture simulant mixed waste, none of the seal materials met the screening criteria. For specific gravity testing of liner materials, the data showed that while all materials with the exception of polypropylene passed the screening criteria, Kel-F, HDPE, and XLPE offered the greatest resistance to the combination of radiation and chemicals.

Nigrey, P.J.; Dickens, T.G.

1997-12-01

258

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

259

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

260

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

NASA Astrophysics Data System (ADS)

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

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

2001-03-01

261

Electronic Structure Study of Cerium Doped Scintillators  

NASA Astrophysics Data System (ADS)

The interest shown in recent years related to cerium doped lanthanum halides, such as LaCl3, LaBr3, and LaI3, is mainly due to their potential applicability as gamma ray scintillation detectors. We have performed a comprehensive theoretical study of these materials to better understand the scintillation process and define the nature of the self trapped exciton (STE) associated with thermally dependent scintillation process. The present work focuses on the study of the luminescence properties of cerium doped lanthanum halide scintillators from the point view of solid state band structure calculations. Our calculated band structures are in good agreement with experimental values. For example, LaCl3 band gap is calculated to be 6.85 eV as compared to approximately 7.0 eV for the experimentally determined value. The theoretically calculated excitation spectra are also compared with the experimental spectra. We find that scintillation efficiencies are dependent on the location of the of Ce^3+ ground 4f and excited 5d levels with respect to the fundamental band gap of the host materials.

Gao, Da; McIlwain, Michael

2008-03-01

262

Percolation Processes in Scintillation of Organic Crystals  

NASA Astrophysics Data System (ADS)

The use of organic crystals as scintillators that can discriminate between incident neutrons and gamma rays is gaining interest, particularly for applications in nonproliferation and diagnostics. Discrimination is achieved by measuring the delay of scintillation from neutrons, which arises from the predominant generation of triplet excited states that must diffuse and undergo a bimolecular Auger process to produce excited singlets before luminescence occurs. To understand this delayed scintillation process, we have studied triplet migration in two organic crystals: trans-stilbene (TS) and diphenylacetylene (DPAC). Both TS and DPAC show delayed neutron scintillation when pure, but the effect is quenched in DPAC if small amounts of TS impurity are present. We find that the first triplet excited state of TS is 0.3 eV lower than that of DPAC, creating a triplet trap in the impure DPAC crystals. Percolation theory is applied to predict a critical concentration of the mixed crystal to restore delayed scintillation, which compares favorably to experiments. We compute the triplet migration rate in different directions in the crystals and discuss the transport anisotropy in view of our percolation model.

Lordi, Vincenzo; Hamel, Sebastien; Carman, Leslie; Payne, Stephen; Zaitseva, Natalia

2010-03-01

263

Light scattering and distribution model for scintillation cameras  

NASA Astrophysics Data System (ADS)

Light distribution in a standard scintillation camera is a complex process. The photons come across many different optical materials and many types of specular and rough optical surfaces. Complexity is further added to the model when the spatial and angular sensitivities of the detection components--the photomultipliers--are considered. To be able to correctly predict the PSF of a gamma camera, we developed a Monte-Carlo ray-tracing model which was subsequently compared to data measured on an existing gamma camera head (PRISM 3000 from Picker International Inc.). The experimental configuration was first replicated: geometry, optical properties of the crystal, light guide, photomultiplier tube window and photocathode, index matching fluid and gamma ray energy. Several other parameters, such as back mirror reflectivity and border reflectivity, were the optimized. Finally an a posteriori modelization of the scattered refracted and reflected fields at the rough interface between the crystal and the light guide was obtained by fitting simulation results to experimental data.

Rioux, Sylvain; Gagnon, Daniel; Lexa, Roger; Valentino, Frank C.

1993-12-01

264

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

265

Amplitude Scintillation at Randle Cliff Derived from Ats-1 Transmissions.  

National Technical Information Service (NTIS)

An amplitude scintillation analysis of vhf radiowave transmissions from the geostationary satellite ATS-1 has been conducted. It has been found that the amplitude scintillation activity is generally less intense during the day than during nocturnal hours....

J. M. Goodman J. E. Blundy

1969-01-01

266

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, ...

267

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

268

Gamma cameras with SDDs coupled to scintillators  

NASA Astrophysics Data System (ADS)

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

Fiorini, Carlo; Longoni, Antonio; Perotti, Francesco; Labanti, Claudio; Kemmer, Josef; Lechner, Peter; Leutenegger, Paolo; Strueder, Lothar

2000-07-01

269

Tracking with capillaries and liquid scintillator  

NASA Astrophysics Data System (ADS)

The technique of glass capillaries filled with liquid scintillator allows the reconstruction of ionizing particle tracks with high spatial resolution. Detectors based on this technique consist of coherent arrays of capillaries having diameters of the order of 20?m. Light signals are amplified by an optoelectronic chain composed of a series of image intensifiers: the readout is performed through a CCD. The ongoing research in the field of liquid scintillators has led to excellent results in terms of information density (>=5hits/mm) and radiation resistance (order of 1MGy). In this paper new results about the effect of ageing and purification of liquid scintillators will be presented. The RD46 collaboration has developed a completely new detector having a readout chain composed of only one image intensifier followed by a new device: a Megapixel Electron Bombarded CCD. First images of neutrino interactions will be shown, together with preliminary measurements of the resolution of the detector.

Annis, P.; Bay, A.; Bonekämper, D.; Buontempo, S.; Chiodi, G.; Ereditato, A.; Fabre, J. P.; Fiorillo, G.; Frekers, D.; Frenkel, A.; Galeazzi, F.; Garufi, F.; Goldberg, J.; Golovkin, S. V.; Hoepfner, K.; Konijn, J.; Kozarenko, E.; Kreslo, I.; Liberti, B.; Martellotti, G.; Medvedkov, A.; Panman, J.; Penso, G.; Petukhov, Yu.; Rondeshagen, D.; Solovjov, A.; Tyukov, V.; Vasil'Chenko, V.; Vilain, P.; Visschers, J. L.; Wilquet, G.; Winter, K.; Wolff, T.; Wong, H.

1997-02-01

270

Monte Carlo study of spatial resolution of the scintillation camera  

Microsoft Academic Search

The aim of this study was to evaluate the influence of different entrance surface treatments of the scintillator on the intrinsic\\u000a spatial resolution of a scintillation camera. The primary scintillation light reflection on the entrance surface of a scintillator\\u000a may be affected by the optical coating of the entrance surface, resulting in either spatial resolution or system detection\\u000a efficiency degradation.

Jie Zhu; XiaoPing Ouyang; Da Chen

2011-01-01

271

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

272

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

273

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

274

Screen optics effects on detective quantum efficiency in digital radiography: Zero-frequency effects  

Microsoft Academic Search

Indirect flat panel imagers have been developed for digital radiography, fluoroscopy and mammography, and are now in clinical use. Screens made from columnar structured cesium iodide (CsI) scintillators doped with thallium have been used extensively in these detectors. The purpose of this article is to investigate the effect of screen optics, e.g., light escape efficiency versus depth, on gain fluctuation

A. R. Lubinsky; Zhao Wei; Goran Ristic; J. A. Rowlands

2006-01-01

275

Fireplace screen  

Microsoft Academic Search

A fireplace screen arrangement is disclosed which includes a frame upon which a pair of mesh screen doors are pivotally mounted for movement between closed and open positions with respect to the fireplace. A damper assembly is provided for regulating the amount of air which is admitted to the fireplace through the screen arrangement. In order to provide convenient opening

Larkins

1985-01-01

276

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

PubMed

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:Tl), 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 approximately 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 the modulation transfer function) as a function of increasing angle of incidence (as well as of the scintillator thickness). Since the noise power behavior was found to be largely independent of the incident angle, the dependence of the DQE on the 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 approximately 30x30 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. PMID:20526032

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

2010-06-04

277

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

NASA Astrophysics Data System (ADS)

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:Tl), 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 the modulation transfer function) as a function of increasing angle of incidence (as well as of the scintillator thickness). Since the noise power behavior was found to be largely independent of the incident angle, the dependence of the DQE on the 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

2010-07-01

278

High-throughput scintillation proximity assay for stearoyl-CoA desaturase-1.  

PubMed

Stearoyl-CoA desaturase (SCD) catalyzes the synthesis of monounsaturated fatty acids and has been implicated in a number of disease states, including obesity and diabetes. To find small-molecule inhibitor leads, a high-throughput scintillation proximity assay (SPA) was developed using the hydrophobic binding characteristics of a glass microsphere scintillant bead to capture SCD1 from a crude lysate of recombinant SCD1 in Sf9 lysate coupled with the strong binding characteristics of an azetidine compound ([(3)H]AZE). The SPA assay was stable over 24 h and could detect compounds with micromolar to nanomolar potencies. A robust 1536-well high-throughput screening assay was developed with good signal-to-noise ratio (10:1) and excellent Z' factor (0.8). A screening collection of 1.6 million compounds was screened at 11 µM, and approximately 7700 compounds were identified as initial hits, exhibiting at least 35% inhibition of [(3)H]AZE binding. Further screening and confirmation with an SCD enzyme activity assay led to a number of new structural leads for inhibition of the enzyme. The SPA assay complements the enzyme activity assay for SCD1 as a tool for the discovery of novel leads in drug discovery. PMID:21406617

Tawa, Paul; Falgueyret, Jean-Pierre; Guiral, Sebastien; Isabel, Elise; Powell, David A; Zuck, Paul; Skorey, Kathryn

2011-03-15

279

A study of the performance of elongated scintillation detectors  

Microsoft Academic Search

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

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

1976-01-01

280

Atmospheric Intensity Scintillation of Stars. II. Dependence on Optical Wavelength  

Microsoft Academic Search

Atmospheric intensity scintillation of stars on milli- and microsecond time scales was extensively measured at the astronomical observatory on La Palma (Canary Island). Scintillation statistics and temporal changes were discussed in Paper I, while this paper shows how scintillation depends on optical wavelength. Such effects originate from the changing refractive index of air, and from wavelength-dependent diffraction in atmospheric inhomogeneities.

D. Dravins; L. Lindegren; E. Mezey; A. T. Young

1997-01-01

281

A fast scintillation detector for analytical X-ray instruments  

Microsoft Academic Search

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

J. L. Radtke

1990-01-01

282

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

283

A new particle detector based on processed plastic scintillating fiber  

Microsoft Academic Search

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

Yongjian Xu; Chundong Hu; Jun Li

2010-01-01

284

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.

S. Normand; B. Mouanda; S. Haan; M. Louvel

2000-01-01

285

Study of a new boron loaded plastic scintillator (revised)  

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

286

Upconverting nanoparticles for optimizing scintillator based detection systems  

DOEpatents

An upconverting device for a scintillation detection system is provided. The detection system comprises a scintillator material, a sensor, a light transmission path between the scintillator material and the sensor, and a plurality of upconverting nanoparticles particles positioned in the light transmission path.

Kross, Brian; McKisson, John E; McKisson, John; Weisenberger, Andrew; Xi, Wenze; Zom, Carl

2013-09-17

287

Radio wave phase scintillation and precision Doppler tracking of spacecraft  

Microsoft Academic Search

Phase scintillation caused by propagation through solar wind, ionospheric, and tropospheric irregularities is a noise process for many spacecraft radio science experiments. In precision Doppler tracking observations, scintillation can be the dominant noise process. Scintillation statistics are necessary for experiment planning and in design of signal processing procedures. Here high-precision tracking data taken with operational spacecraft (Mars Observer, Galileo, and

J. W. Armstrong

1998-01-01

288

Prediction of tropospheric scintillation on satellite links from radiosonde data  

Microsoft Academic Search

On the basis of radiosonde data, a new method is proposed for predicting tropospheric scintillation effects on slant paths. It stems from a rigorous statistical development and consists of two steps. First, statistical features of tropospheric turbulence responsible for scintillation are extracted from the analysis of a large amount of radiosonde ascents. Second, long-term scintillation statistics are inferred from these

Hugues Vasseur

1999-01-01

289

Availability Impact on GPS Aviation due to Strong Ionospheric Scintillation  

Microsoft Academic Search

Strong ionospheric scintillation due to electron density irregularities inside the ionosphere is commonly observed in the equatorial region during solar maxima. Strong amplitude scintillation causes deep and frequent Global Positioning System (GPS) signal fading. Since GPS receivers lose carrier tracking lock at deep signal fading and the lost channel cannot be used for the position solution until reacquired, ionospheric scintillation

Jiwon Seo; Todd Walter; Per Enge

2011-01-01

290

Full-absorption scintillation spectrometer for neutrons  

NASA Astrophysics Data System (ADS)

A full-absorption scintillation spectrometer for neutrons (volume of scintillator = 24 1) has been developed and employed in investigations of muon catalysed processes. Its application allows: (a) considerably increasing the rate of accumulation of events; (b) efficiently using muon catalysis multiplicity for fuller and more reliable determination of its parameters; (c) significantly reducing uncertainty in the calculated and experimentally found values of neutron detection efficiency. The device combines good spectrometric properties for neutron energies En = 1-6 MeV and reliable n-? separation (the degree of separation for a Pu-Be source <~ 10-3 starting from an electron energy of 50 keV).

Dzhelepov, V. P.; Filchenkov, V. V.; Konin, A. D.; Rudenko, A. I.; Solovieva, G. M.; Zinov, V. G.

1988-06-01

291

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

292

Effects of radiation on scintillating fiber performance  

SciTech Connect

Continued rapid improvements in formulations for scintillating fibers require the ability to parameterize and predict effects of radiation on detector performance. Experimental techniques necessary to obtain desired information and calculational procedures used in performing predictions for hadron scintillating fiber calorimetry in the Superconducting Supercollider environment are described. The experimental techniques involve control of the testing environment, consideration of dose rate effects, and other factors. The calculations involve the behavior of particle showers in the detector, expected levels of radiation, and parameterization of the radiation effects. A summary of significant work is also presented.

Young, K.G.; Bauer, M.L.; Cohn, H.; Efremenko, Yu.; Gordeev, A.; Kamyshkov, Yu.; Onopienko, D.; Savin, S.; Shmakov, K.; Tarkovsky, E. (Oak Ridge National Lab., TN (United States)); Carey, R.; Rothman, M.; Sulak, L.; Worstell, W. (Boston Univ., MA (United States)); Paar, H. (Univ. of California, San Diego, La Jolla, CA (United States))

1993-08-01

293

Effects of radiation on scintillating fiber performance  

SciTech Connect

Continued rapid improvements in formulations for scintillating fibers require the ability to parameterize and predict effects of radiation on detector performance. Experimental techniques necessary to obtain needed information and calculational procedures used in performing predications for hadron scintillating fiber calorimetry in the Superconducting Supercollider environment are described. The experimental techniques involve control of the testing environment, consideration of dose rate effects, and other factors. These calculations involve the behavior of particle showers in the detector, expected levels of radiation, and parameterization of the radiation effects. A summary of significant work is also presented.

Bauer, M.L.; Cohn, H.; Efremenko, Yu.; Gordeev, A.; Kamyshkov, Yu.; Onopienko, D.; Savin, S.; Shmakov, K.; Tarkovsky, E.; Young, K.G. [Oak Ridge National Lab., TN (United States); Carey, R.; Rothman, M.; Sulak, L.; Worstell, W. [Boston Univ., MA (United States); Parr, H. [California Univ., San Diego, La Jolla, CA (United States)

1992-12-31

294

Detection of charged particles and X-rays by scintillator layers coupled to amorphous silicon photodiode arrays  

SciTech Connect

Hydrogenated amorphous silicon (a-Si:H) p-i-n diodes with transparent metallic contacts are shown to be suitable for detecting charged particles, electrons, and X-rays. When coupled to a suitable scintillator using CsI(Tl) as the scintillator we show a capability to detect minimum ionizing particles with S/N {approximately}20. We demonstrate such an arrangement by operating a p-i-n diode in photovoltaic mode (reverse bias). Moreover, we show that a p-i-n diode can also work as a photoconductor under forward bias and produces a gain yield of 3-8 higher light sensitivity for shaping times of 1 {mu}s. n-i-n devices have similar optical gain as the p-i-n photoconductor for short integrating times ( < 10{mu}s). However, n-i-n devices exhibit much higher gain for a long term integration (10ms) than the p-i-n ones. High sensitivity photosensors are very desirable for X-ray medical imaging because radiation exposure dose can be reduced significantly. The scintillator CsI layers we made have higher spatial resolution than the Kodak commercial scintillator screens due to their internal columnar structure which can collimate the scintillation light. Evaporated CsI layers are shown to be more resistant to radiation damage than the crystalline bulk CsI(Tl).

Jing, T.; Drewery, J.; Hong, W.S.; Lee, H.; Kaplan, S.N.; Perez-Mendez, V. [Lawrence Berkeley Lab., CA (United States); Goodman, C.A.; Wildermuth, D. [Air Techniques, Inc. Hicksville, NY (United States)

1995-04-01

295

Attention Guiding in Multimedia Learning  

ERIC Educational Resources Information Center

Comprehension of an illustrated document can involve complex visual scanning in order to locate the relevant information on the screen when this is evoked in spoken explanations. The present study examined the effects of two types of attention-guiding means (color change or step-by-step presentation of diagram elements synchronized with a spoken…

Jamet, Eric; Gavota, Monica; Quaireau, Christophe

2008-01-01

296

Guided Wave Training and Certification  

Microsoft Academic Search

Long range guided wave inspection technology which was patented by Imperial College London in 1997 has been extensively applied in the petrochemical industry to screen long lengths of pipe from a single location. The initial technology was used only for a limited number of applications; this subsequently was improved to be used in different industries and operational environments. The experience

A. DEMMA; M. EVANS; D. ALLEYNE; B. PAVLAKOVIC; J. FONG; T. VOGT

297

Satellite guide  

NASA Astrophysics Data System (ADS)

The University of Rhode Island's Sea Grant Program has published what it calls the first user's guide to environmental satellite data. Written by Peter Cornillon, an oceanographer at Rhode Island, the guide spells out which agencies distribute information from 14 environmental satellites. For those unfamiliar with remote-sensing techniques, the guide also delineates the various sensors the satellites carry and the types of information they produce. The heart of the looseleaf-formatted guide is an overview of the characteristics and objectives of each satellite and the characteristics of the data available.

298

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

299

Simulation of GPS Scintillation and TEC Using Rocket Borne Ionospheric Density Measurements  

NASA Astrophysics Data System (ADS)

Scintillations in trans-ionospheric radio signals arise as the signal propagates through naturally occurring plasma irregularities. If the receiver, satellite, or ionospheric irregularities are in motion, a time series of signal fading and phase fluctuations will occur at the receiver. It is well known that diffraction of the radio phase front produces amplitude and phase fluctuations even at GPS frequencies. Significant progress in scintillation modeling has been made since the dawn of the space age, with most of the efforts focused on statistically characterizing the plasma structure and radio wave fluctuations. In an attempt to better relate measured scintillations to the physical processes that cause them, we present results from modeling scintillation using a standard phase-screen approach but with electron density distributions measured from rocket borne Langmuir probes as input to model. The result of our model is simulated GPS phase and amplitude for a receiver on the ground, which we compare to actual GPS measurements from the Italian INGV network in the region. The ICI-2 Rocket was launched into moderate cusp irregularities on Dec 5, 2008, and measured three regions of F-region density fluctuation that appear consistent with the F-region gradient drift instability. These fluctuations caused modeled S4 of 0.2 and sigma phi of 0.1 consistent with nearby GPS measurements. One of the unexpected results of this work is that we find that the weak scintillations can cause non-physical fluctuations in TEC that peak at values as high as 2 TECU (~20 cm range error) and appear as TEC micropulsations, when indeed they are merely differenced diffraction patterns from two frequencies. This finding will be of interest to both practical GPS applications and scientists interested in using GPS to measure physical micropulsations.

Dyrud, L.; Murr, D.; Moen, J. I.; Alfonsi, L.

2010-12-01

300

Selective screening for chlamydial infection: which criteria to use?  

Microsoft Academic Search

Background: Screening sexually active women for Chlamydia trachomatis is necessary to detect asymptomatic infections. Selective screening is a common strategy because universal screening is too costly in many settings. In order to guide local programs in the choice of selective screening criteria, we examined the performance of previously proposed screening criteria for C trachomatis.Methods: A clinic-based, cross-sectional study was conducted

William C Miller; Irving F Hoffman; Judy Owen-O’Dowd; J. Todd McPherson; April Privette; John L Schmitz; Gina Woodlief; Peter A Leone

2000-01-01

301

Rapid screening of 90Sr activity in water and milk samples using Cherenkov radiation  

Microsoft Academic Search

A method for screening 90Sr in milk samples is proposed. This method is based on a liquid scintillation technique taking advantage of Cherenkov radiation, which is produced in a liquid medium and then detected by the photomultipliers of a Liquid Scintillation Counter (LSC).Twenty millilitres of water and milk samples spiked with various concentrations of 90Sr\\/90Y in equilibrium were added in

K. C. Stamoulis; K. G. Ioannides; D. T. Karamanis; D. C. Patiris

2007-01-01

302

Comparison of WBMOD scintillation predictions with GPS scintillation observations during solar maximum conditions  

Microsoft Academic Search

In this paper we investigate the performance of the global scintillation model WBMOD in the southeast Asian region during the sunspot maximum year 2000. We compare model predictions of scintillation with GPS obser- vations from ve of our stations in the region over the entire year. The comparisons are made at S4 thresholds of 0.3 and 0.6 which represent the

M. A. Cervera; R. M. Thomas; K. M. Groves; A. Ghaar bin Ramli; W. Salwa Hassan

303

Scintillating luminescence of cerium-doped dense oxide glass  

NASA Astrophysics Data System (ADS)

New dense oxide glass scintillator has been discovered in the system: B2O3-SiO2-Al2O3- Gd2O3 doped with trivalence cerium. This scintillator has a unique combination of properties including high scintillating light output, high density and desirable emission wavelength, large radiation hardness, short radiation length, and easy to produce in large size and low price. Here we compare the properties with those of the two recently developed dense scintillators: Ce3+-doped fluorophosphate glass and Ce3+-doped fluorohafnate glass, and with those of the three most widely used scintillating crystals Ce:YAP,CeF3 and BGO.

Jiang, Chun; Zhang, Junzhou; Gan, Fu-Xi

1999-10-01

304

Scintillation of pseudo-Bessel correlated beams in atmospheric turbulence.  

PubMed

The concept of pseudo-Bessel correlated beams is introduced, and their scintillation properties on propagation through turbulence are investigated. By using the Rytov approximation, the scintillation index of pseudo-Bessel correlated beams is formulated in weak turbulence. The study of scintillation is extended into strong turbulence by numeric simulations. It is shown that by choosing an appropriate coherence parameter, pseudo-Bessel correlated beams have lower scintillation than comparable fully coherent beams in both weak and strong turbulence. In addition, the configuration of pseudo-Bessel correlated beams is modified by adding a horizontal beamlet; the scintillation properties of these modified beams are also discussed. PMID:21119747

Gu, Yalong; Gbur, Greg

2010-12-01

305

Laguerre-Gaussian beam scintillation on slant paths  

NASA Astrophysics Data System (ADS)

Scintillation evaluations for Laguerre-Gaussian (LG) beams for slant paths are made using Rytov approximation. On- and off-axis scintillation is formulated and calculated up to several tens of kilometers of slant distances for different zenith angles. Scintillation index variations against radial receiver point and different source sizes are also investigated. In all cases evaluated, it is found that LG beams with higher radial mode numbers result in less scintillation than Gaussian beam. Kolmogorov spectrum function is utilized in the scintillation calculations.

Yüceer, Mehmet; Eyyubo?lu, Halil T.

2012-11-01

306

Neutron/gamma discrimination properties of composite scintillation detectors  

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

307

Plastic scintillators with efficient neutron/gamma pulse shape discrimination  

NASA Astrophysics Data System (ADS)

A possibility of manufacturing plastic scintillators with efficient neutron/gamma pulse shape discrimination (PSD) is demonstrated using a system of a polyvinyltoluene (PVT) polymer matrix loaded with a scintillating dye, 2,5-diphenyloxazole (PPO). Similarities and differences of conditions leading to the rise of PSD in liquid and solid organic scintillators are discussed based on the classical model of excited state interaction and delayed light formation. First characterization results are presented to show that PSD in plastic scintillators can be of the similar magnitude or even higher than in standard commercial liquid scintillators.

Zaitseva, Natalia; Rupert, Benjamin L.; Pawe?czak, Iwona; Glenn, Andrew; Martinez, H. Paul; Carman, Leslie; Faust, Michelle; Cherepy, Nerine; Payne, Stephen

2012-03-01

308

Cancer screening.  

PubMed

Cancer screening is a complicated science. Each screening intervention must be carefully assessed before it is widely implemented. A screening test can falsely appear useful as it finds disease at an early stage and leads to intervention and cure. Such a test can be harmful to the population screened if it commonly finds disease that fulfills the pathologic criteria of cancer but behaves indolently (meaning it would never harm the host). Such "pseudo-disease" or "overdiagnosed disease" has been demonstrated in many malignancies including cancers of the lung, breast, and especially the prostate. The nature of each specific screening test and each disease is such that some screened patients may receive unnecessary treatment with all its complications and risk. Alternatively, some screening technologies have been proven useful providing net benefit to the population screened. Often these beneficial technologies are underused. These screening technologies if widely implemented have the potential of saving countless lives. Many available screening tests have tremendous potential in terms of benefit, but have yet to be fully assessed. At the minimum, patients should be informed of what is known, what is not known, and what is believed about these tests. PMID:15124134

Brawley, Otis W

2004-04-01

309

Genetic Screening  

PubMed Central

Current approaches to genetic screening include newborn screening to identify infants who would benefit from early treatment, reproductive genetic screening to assist reproductive decision making, and family history assessment to identify individuals who would benefit from additional prevention measures. Although the traditional goal of screening is to identify early disease or risk in order to implement preventive therapy, genetic screening has always included an atypical element—information relevant to reproductive decisions. New technologies offer increasingly comprehensive identification of genetic conditions and susceptibilities. Tests based on these technologies are generating a different approach to screening that seeks to inform individuals about all of their genetic traits and susceptibilities for purposes that incorporate rapid diagnosis, family planning, and expediting of research, as well as the traditional screening goal of improving prevention. Use of these tests in population screening will increase the challenges already encountered in genetic screening programs, including false-positive and ambiguous test results, overdiagnosis, and incidental findings. Whether this approach is desirable requires further empiric research, but it also requires careful deliberation on the part of all concerned, including genomic researchers, clinicians, public health officials, health care payers, and especially those who will be the recipients of this novel screening approach.

Burke, Wylie; Tarini, Beth; Press, Nancy A.; Evans, James P.

2011-01-01

310

Thin GSO scintillator for neutron detection.  

National Technical Information Service (NTIS)

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(Tl). The enormous cross section of Gd for capture of.thermal neutrons makes GSO a candidate for novel types of neut...

P. L. Reeder

1994-01-01

311

Waveshifting fiber readout of lanthanum halide scintillators  

NASA Astrophysics Data System (ADS)

Newly developed high-light-yield inorganic scintillators coupled to waveshifting optical fibers provide the capability of efficient X-ray detection and millimeter scale position resolution suitable for high-energy cosmic ray instruments, hard X-ray/gamma ray astronomy telescopes and applications to national security. The CASTER design for NASA's proposed Black Hole Finder Probe mission, in particular, calls for a 6 8 m2 hard X-ray coded aperture imaging telescope operating in the 20 600 keV energy band, putting significant constraints on cost and readout complexity. The development of new inorganic scintillator materials (e.g., cerium-doped LaBr3 and LaCl3) provides improved energy resolution and timing performance that is well suited to the requirements for national security and astrophysics applications. LaBr3 or LaCl3 detector arrays coupled with waveshifting fiber optic readout represent a significant advance in the performance capabilities of scintillator-based gamma cameras and provide the potential for a feasible approach to affordable, large area, extremely sensitive detectors. We describe some of the applications and present laboratory test results demonstrating the expected scintillator performance.

Case, G. L.; Cherry, M. L.; Stacy, J. G.

2006-07-01

312

High-Z Organic-Scintillation Solution.  

National Technical Information Service (NTIS)

In the present experiment, an attempt is made to raise the average Z of a scintillation solution with as little attendant quenching as possible. Since high-Z atoms quench by means of a close encounter, such encounters are minimized by the use of alkyl gro...

I. B. Berlman J. M. Fluornoy C. B. Ashford P. B. Lyons

1983-01-01

313

Fluorescent compounds for plastic scintillation applications  

NASA Astrophysics Data System (ADS)

Several 2-(2'-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 C-60 source have also been performed.

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

1994-04-01

314

Intensity Scintillation and Astronomical Quantum Observation  

Microsoft Academic Search

Holography is 3D imaging which can record intensity and phase at the same time. The importance of construct hologram is holographic recording and wavefront reconstruction. It is surprised that holography be discovered in study interstellar scintillation for pulsar provide a coherent light source recently. I think that is speckle hologram and speckle interference(i.e. intensity interference), and use modern technique which

Jiang Dong

2008-01-01

315

Use of Stilbene Scintillator for gamma Spectrometry.  

National Technical Information Service (NTIS)

This report deals with the set-up and calibration of a scintillation gamma spectrometer with a single stilbene crystal, for measuring gamma spectra in the energy range from 0.5-10-MeV. The spectrometer discriminates between the measured gamma rays and the...

A. S. Makarious R. Megahid R. M. A. Maayouf

1978-01-01

316

Light attenuators for plastic scintillation detectors  

Microsoft Academic Search

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

Tretyakova; Ch. A

1987-01-01

317

Fabrication and measurements of plastic scintillating fibers  

Microsoft Academic Search

Sixty kilometers of plastic scintillating fibers, 1mm in diameter, have been manufactured using a preform\\/tube technology. The fibers consist of a polystyrene core surrounded by a polymethylmethacrylate cladding. The fabrication method is described and evaluated both qualitatively and quantitatively. A great effort has been made in order to measure the optical properties of the polymer at the different steps of

P. P. Rebourgeard; F. Rondeaux; J. P Baton; G. Besnard; H. Blumenfeld; M. Bourdinaud; J. Calvet; J.-C Cavan; R. Chipaux; A. Giganon; J. Heitzmann; C. Jeanney; P. Micolon; M. Neveu; T. Pedrol; D. Pierrepont; J.-C Thévenin

1999-01-01

318

Refractive scintillation in the interstellar medium  

Microsoft Academic Search

It is shown here that the large-scale component of interstellar scintillation which causes the slow variation in the apparent intensity of pulsars on time scales of days to months can be greatly enhanced when the turbulence spectrum has a limiting inner scale of the order 10 to the 9th m. This solution is extended to the spherical diverging geometry appropriate

W. A. Coles; B. J. Rickett; J. L. Codona; R. G. Frehlich

1987-01-01

319

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

320

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

321

LET effects of neutron irradiated plastic scintillators  

Microsoft Academic Search

The induced optical absorptions of polymers polystyrene (PS), polymethylmethacrylate (PMMA) and polyvinyltoluene (PVT), irradiated by neutrons and in ? fields, were measured for equal doses. The polymers are the most important bases for the use as plastic scintillators. The permanent damage in PS and PVT after recovery in air is larger for neutron than for ? irradiation. Electron spin resonance

B. Bodmann; S. Göb; U. Holm

2003-01-01

322

Gammaradiation damage effects on plastic scintillators  

Microsoft Academic Search

The effect of radiation damage on a number of different scintillating materials has been investigated by measuring the apparent maximum energy change represented by the shift in the beta-spectrum end-point obtained from Tl. The damage curves have been shown to be represented by the equation y = A(1 - e ) where y is the percentage apparent energy change, x

G. Oldham; A. R. Ware

1975-01-01

323

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

324

Scintillating fibre hodoscopes for COSY-TOF  

SciTech Connect

At the cooler synchrotron COSY (Forschungszentrum Juelich, Germany) detector arrays of scintillating fibres are used in different experiments. In this contribution we mainly report on the experience with scintillating fibre hodoscopes in the COSY Time-of-Flight (TOF) spectrometer. One of the physical topics in this experiment is the study of the associated strangeness production in the reactions pp{yields}K{sup +}{lambda}p, K{sigma}{sup +}n, K{sup +}{sigma}{sup 0}p and K{sup 0}{sigma}{sup +}p. The apparatus consists of an inner start detector system close to the target and an outer stop detector system both mounted inside a vacuum vessel. For the inner detector system apart from microstrip components arrays of scintillating fibres are used to measure particle tracks and the decay vertices of the hyperons, thus allowing to identify and reconstruct the events of interest. Furthermore, scintillating fibre hodoscopes are installed for the online measurement of profiles and intensity of the proton beam at COSY-TOF. In both mentioned detector systems squared fibers are in operation together with multianode photomultipliers.

Eyrich, W.; Fritsch, M.; Hauffe, J.; Metzger, A.; Stinzing, F.; Wagner, M.; Wirth, S. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, D-91058 Erlangen (Germany)

1998-11-09

325

Scintillation counter with rotatable light seal  

Microsoft Academic Search

A light seal for the counting chamber of a scintillation counter comprises a ring shutter mounted in the shielded housing which forms the counting chamber. The ring shutter is mounted for rotation between an open position where an aperture in the ring shutter is aligned with an opening into the shielding housing to permit transfer of sample vials in and

Johnson

1980-01-01

326

Quench determination in liquid scintillation counting systems  

Microsoft Academic Search

A method and apparatus for measuring the degree of quench in a liquid scintillation sample by irradiating the sample with a standard source, such as a cesium-137 gamma source, to produce a Compton scattered electron distribution exhibiting a Compton edge configuration as the leading edge are described. For increasing the quench levels in the sample, the Compton edge shifts to

1978-01-01

327

Optimization of Shielded Scintillator for Neutron Detection  

NASA Astrophysics Data System (ADS)

The High Energy Density Physics group is interested in the basic science of creating a neutron and gamma ray source. The neutrons and gamma rays are produced by accelerating ions via a laser into a target and creating fusion neutrons and gamma rays. A scintillator and photomultiplier tube will be used to detect these neutrons. Neutrons and photons produce ionizing radiation in the scintillator which then activates metastable states. These metastable states have both short and long decay rates. The initial photon count is orders of magnitude higher than the neutron count and poses problems for accurately detecting the neutrons due to the long decay state that is activated by the photons. The effects of adding lead shielding on the temporal response and signal level of the neutron detector will be studied in an effort to minimize the photon count without significant reduction to the temporal resolution of the detector. MCNP5 will be used to find the temporal response and energy deposition into the scintillator by adding lead shielding. Results from the simulations will be shown. Optimization of our scintillator neutron detection system is needed to resolve the neutron energies and neutron count of a novel neutron and gamma ray source.

Belancourt, Patrick; Morrison, John; Akli, Kramer; Freeman, Richard

2011-11-01

328

Scintillating fiber calorimeters with cast absorbers  

Microsoft Academic Search

The technology to construct cast lead-eutectic scintillating fiber calorimeters for measuring the energy of hadron and electromagnetic showers is discussed. The lead eutectic injection process, mold construction and release equipment, and fiber preform are described, along with beam test results on prototypes. Novel extensions of the technique include liquid fiber forward calorimeters, and shot-loading of the molten eutectic to achieve

D. Brown; R. Carey; S. T. Dye; E. Hazen; D. Higby; J. P. Miller; B. L. Roberts; L. Sulak; C. Wang; W. Worstell; D. Boccuzzi; D. Scrofani; K. Segall; D. Wall; D. R. Winn; C. Bromberg; J. Huston; R. Miller; C. Yosef; A. David; N. Diaczenko; S. Zaman; A. Sanzgiri; R. Webb; D. Acosta; J. Branson; B. Ong; H. Paar; M. Sivertz; D. Thomas; F. Ayer; C. Elder; D. Sullivan

1991-01-01

329

Scintillation Properties of Unactivated Calcium Fluoride Crystal  

NASA Astrophysics Data System (ADS)

This paper presents scintillation properties of unactivated calcium fluoride exposed to X-rays and ?-rays from 6 keV to 662 keV. The relative pulse heights and linearity response have been measured. The photoelectron yields have been obtained. A clear full energy photopeak for Cs137 (662 keV) ?-rays has been observed.

Zhu, Y. C.; Lu, J. G.; You, K.; Shao, Y. Y.; Sun, H. S.; Zheng, Z. P.; Ye, M. H.; Cui, F. Z.; Yu, C. J.; Jiang, G. J.

330

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

331

A rapid method for the simultaneous determination of gross alpha and beta activities in water samples using a low background liquid scintillation counter  

Microsoft Academic Search

The radiological examination of water requires a rapid screening technique that permits the determination of the gross alpha and beta activities of each sample in order to decide if further radiological analyses are necessary. In this work, the use of a low background liquid scintillation system (Quantulus 1220) is proposed to simultaneously determine the gross activities in water samples. Liquid

J. A. Sanchez-Cabeza; Ll. Pujol

1995-01-01

332

Optimization of a Scintillator for the Measurement of Positrons from Trapped, Polarized ^37K  

NASA Astrophysics Data System (ADS)

Precision beta decay experiments can be used to test the Standard Model via their value of correlation parameters. The TRINAT collaboration is performing such an experiment using a source of polarized ^37K from a magneto optical trap. The momentum of an emitted positron will be detected using a Silicon strip detector backed by a plastic scintillator. The goal of my research was to optimize the readout of the scintillator by testing different experimental setups. The front face and sides of the scintillator and light guide were wrapped with various reflective materials to find which maximized the light output. We found that one layer of Teflon tape on the front face with a loose wrapping of 3M-ESR (Enhanced Spectral Reflector) on the sides was optimal. We then tested the position dependence of this detector by moving a collimated source of betas across the front face, showing only a (5.9 ± 0.5)% reduction in light collection at the edge compared to the center. The product of this work will be used in the upcoming TRINAT experiment measuring the beta asymmetry of ^37K.

France, Erin; Melconian, Dan

2011-10-01

333

Cancer screening.  

PubMed

Table 3 provides a summary of key recommendations for each cancer site discussed in this chapter. One of the unifying principles of cancer screening is that every clinician or group practice needs to define an explicit screening policy. Resources must then be devoted to implementing this policy, evaluating adherence, and improving performance. PMID:12529905

Wender, Richard C; Smith, Robert; Harper, Diane

2002-09-01

334

Genetic Screening  

NSDL National Science Digital Library

Many genetic disorders can be detected with tests of blood and chromosomes. Genetic screening is the large-scale use of these tests as part of the public health program. Different members of society, worldwide, have advocated genetic screening to achieve different goals. This chapter provides a critical analysis of this controversial issue.

Slesnick, Irwin

2004-01-01

335

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

336

Correlation of In-Situ Plasma Irregularities with Ground-Based Scintillation Measurements  

NASA Astrophysics Data System (ADS)

The Planar Langmuir Probe (PLP) instrument on the C/NOFS satellite measures in-situ ion number density fluctuations at frequencies up to 1024 Hz. These measurements are used to construct phase screen representations of the effect of the ionosphere on trans-ionospheric radiowave propagation. Since its initialization in May, 2008, PLP has detected large numbers of highly structured ionospheric regions in the equatorial belt. We will present an overview of the measurements and will examine the relationships between the observation of in-situ irregularities and measurements of UHF and GPS scintillation from SCINDA sites beneath the satellite orbital track.

Hunton, D. E.; Roddy, P. A.; Ballenthin, J. O.; Bonito, N.; Groves, K.

2008-12-01

337

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

338

Predictors of Cervical Cancer Screening for Rarely or Never Screened Rural Appalachian Women  

Microsoft Academic Search

:Background and Purpose. Women who have not had a Papanicolaou test in five years or more have increased risk of developing invasive cervical cancer. This study compares Appalachian women whose last screening was more than one year ago but less than five years ago with those not screened for the previous five years or more.Methods. Using PRECEDE\\/PROCEED as a guide,

Mark B. Dignan; Nancy E. Schoenberg; Christina R. Studts; Jennifer Hatcher; Lisa M. Turner

2011-01-01

339

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

340

Transparent Ceramic Scintillator Fabrication, Properties and Applications  

SciTech Connect

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

2008-08-24

341

Neutron detection with single crystal organic scintillators  

NASA Astrophysics Data System (ADS)

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, Natalia P.; Newby, Jason; Hamel, Sebastien; Carman, Leslie; Faust, Michelle; Lordi, Vincenzo; Cherepy, Nerine J.; Stoeffl, Wolfgang; Payne, Stephen A.

2009-08-01

342

Scintillating 99Tc Selective Ion Exchange Resins  

SciTech Connect

Scintillating technetium (99Tc) selective ion exchange resins have been developed and evaluated for equilibrium capacities and detection efficiencies. These resins can be utilized for the in-situ concentration and detection of low levels of pertechnetate anions (99TcO4-) in natural waters. Three different polystyrene type resin support materials were impregnated with varying amounts of tricaprylmethylammonium chloride (Aliquat 336) extractant, several different scintillating fluors and wavelength shifters. The prepared resins were contacted batch-wise to equilibrium over a wide range of 99TcO4- concentrations in natural water. The measured capacities were used to develop Langmuir adsorption isotherms for each resin. 99Tc detection efficiencies were determined and up to 71.4 ± 2.6% was achieved with some resins. The results demonstrate that a low level detection limit for 99TcO4- in natural waters can be realized.

Mitchell Greenhalgh; Richard D. Tillotson

2012-07-01

343

Radiation damage effects on liquid scintillating fibers  

NASA Astrophysics Data System (ADS)

The effects of radiation on liquid scintillating fibers composed of borosilicate glass (Pyrex) tubing in combination with a high refractive index liquid scintillator are investigated. The fiber components (tubes, liquids and liquids in tubes), were irradiated in a nuclear reactor with doses exceeding 100 megarads. It was found that the discoloration of the glass tubing does not degrade the optical properties of the fibers - in fact, the attenuation length of fibers using irradiated tubes are longer than those using non irradiated tubes. The attenuation lengths of the liquids in this study appeared to be shortened by the radiation. However, it was found that no deposits or other surface damage occurred on the surfaces of the tubes containing the liquids so the irradiated fibers could be rejuvenated by simply adding fresh liquid.

Gui, Mei; Huson, F. R.; Ostrovsky, Tina; Reese, Dan; Suson, Dan; White, J. T.

1993-01-01

344

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

345

Small inorganic scintillators as neutron detectors  

SciTech Connect

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

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

1998-12-01

346

Discrimination of recoil backgrounds in scintillating calorimeters  

NASA Astrophysics Data System (ADS)

The alpha decay of 210Po is a dangerous background to rare event searches. Here, we describe observations related to this alpha decay in the Cryogenic Rare Event Search with Superconducting Thermometers (CRESST). We find that lead nuclei show a scintillation light yield in our CaWO crystals of 0.0142±0.0013 relative to electrons of the same energy. We describe a way to discriminate this source of nuclear recoil background by means of a scintillating foil, and demonstrate its effectiveness. This leads to an observable difference in the pulse shape of the light detector, which can be used to tag these events. Differences in pulse shape of the phonon detector between lead and electron recoils are also extracted, opening the window to future additional background suppression techniques based on pulse shape discrimination in such experiments.

Lang, R. F.; Angloher, G.; Bauer, M.; Bavykina, I.; Bento, A.; Brown, A.; Bucci, C.; Ciemniak, C.; Coppi, C.; Deuter, G.; von Feilitzsch, F.; Hauff, D.; Henry, S.; Huff, P.; Imber, J.; Ingleby, S.; Isaila, C.; Jochum, J.; Kiefer, M.; Kimmerle, M.; Kraus, H.; Lanfranchi, J.-C.; Malek, M.; McGowan, R.; Mikhailik, V. B.; Pantic, E.; Petricca, F.; Pfister, S.; Potzel, W.; Pröbst, F.; Roth, S.; Rottler, K.; Sailer, C.; Schäffner, K.; Schmaler, J.; Scholl, S.; Seidel, W.; Stodolsky, L.; Tolhurst, A. J. B.; Usherov, I.; Westphal, W.

2010-02-01

347

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

348

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

NASA Astrophysics Data System (ADS)

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 network currently consists of sixteen stations distributed around the globe and the data have been used to conduct numerous studies on the characteristics and climatology of equatorial scintillation. The present study focuses on COSMIC RO and SCINDA data during the three COSMIC campaigns in 2006. Radio occultation events are selected by requiring that ionospheric scintillation was detected by the SCINDA VHF scintillation monitor at Kwajalein, and that the occultation ray path intersected the Kwajalein longitude below the satellite altitude, which varied from 500 to 800 km for the six FORMOSAT-3 satellites. In order to exclude tropospheric effects, only GPS signal amplitudes from FORMOSAT-3 with ray path tangent altitudes above 100 km are considered. Locations of ionospheric scintillation are estimated by triangulation using the satellites and the SCINDA ground station. Airglow images at Kwajalein are also used to confirm occurrence of equatorial ionospheric scintillations. For the selected events, large amplitude L1 and L2 scintillations tend to occur at altitudes below 200 km at frequencies around 0.5 Hz. The results are discussed as a potential path toward better specifying the occurrence of equatorial scintillations.

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

2007-05-01

349

Testing of a scintillating fiber PET system  

NASA Astrophysics Data System (ADS)

We are continuing the characterization of a PET module using plastic scintillating fibers coupled to position sensitive photomultipliers. The sensitivity in air and the resolution in air and water are tabulated for a source positioned at nine locations within the detector field of view. The full width half maximum resolution for a 0.5 mm diameter Na-22 source in air and water is approximately 2.5 m. The sensitivity is 19 c.p.s./(mu) Ci.

Nelson, Gregory S.; Chaney, Roy C.; Fenyves, Ervin J.; Hammack, H.; Hudson, Cheri; Antich, Peter P.; Anderson, Jon A.

1993-10-01

350

a Subminiature Scintillation Detector for Catheter Operation  

NASA Astrophysics Data System (ADS)

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

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

2006-04-01

351

A readout system for plastic scintillating fibers  

Microsoft Academic Search

A readout system for plastic scintillating fibers has been developed using a multi-anode microchannel photomultiplier tube operated in a 5 kG magnetic field and the CMOS MX4 microplexer chip. The microchannel photomultiplier tube with an anode array of 10×10 is coupled to an array of fibers using a precise alignment procedure. Each readout unit is capable of sampling signals from

H. Akbari; J. Bao; C.-Y. Chien; H. Fenker; R. Fitzgerald; P. Fisher; M. Glaubman; A. Grimes; H. Hofer; I. Horvath; D. Kaplan; K. Lanius; I. Leedom; M. MacDermott; J. Mnich; D. Newman; J. Orndorff; A. Pevsner; S. Reucroft; J. Rose; J. Spangler; C. Spartiotis; F. Tonisch; G. Viertel; S. Waldmeier; L. Zehnder

1991-01-01

352

Interplanetary Scintillation Pushchino Survey II (Kopylov+, 2004)  

Microsoft Academic Search

We present the results of optical identification of 248 interplanetary scintillating (IPS) radio sources from the Pushchino Survey (PS) in the area of 0.11sr with the center at RA=10h28m, DE=+41{deg}. All 260 counterparts of IPS radio sources from the 7C and FIRST catalogues, which had been found in Paper I (Cat. ), were considered. We used USNO-B1.0 catalogue (limiting magnitude

A. I. Kopylov; V. S. Artyukh; F. G. Kopylova

2005-01-01

353

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

354

Mercuric Iodide Photodetectors for Scintillation Spectroscopy.  

National Technical Information Service (NTIS)

We have measured the responses to sup 137 Cs (662 keV) of both a 1-inch-diam by 2-inch-thick NaI(Tl) scintillator optically coupled to a 1-inch-diam by 800- mu m-thick mercuric iodide (HgI sub 2 ) photodetector, and a 1-cm-diam by 1-cm-thick CaWO sub 4 sc...

J. Markakis C. Ortale W. Schnepple J. Iwanczyk A. Dabrowski

1984-01-01

355

Optical transducers for scintillating fiber readout  

SciTech Connect

Characteristics of optical-to-electronic transducers which are currently on the market or which will soon be available are discussed in the context of particle detectors using scintillating and wavelength-shifting fibers. It is shown that the most promising avenue for progress in detector development is via the use of solid state transducers, and that these would benefit from the development of long-wavelength light emitters.

Fenker, H.

1992-05-01

356

Statistics of Radar Cross Section Scintillations  

Microsoft Academic Search

The appropriateness of the two-parameter beta distribution as a characterization of RCS scintillation for a complex target is developed and discussed with particular attention to evidence afforded by experimental data. Distributions of measured data supplied to the authors by the Boeing Corporation for the 727-100C aircraft and by Dynalectron Corporation for the RATSCAT-measured drone are compared with Rayleigh, chi-square. log-normal,

J. W. Follin Jr; F. C. Paddison; A. L. Maffett

1984-01-01

357

Observations of interplanetary scintillation in China  

NASA Astrophysics Data System (ADS)

The Sun affects the Earth in multiple ways. In particular, the material in interplanetary space comes from coronal expansion in the form of solar wind, which is the primary source of the interplanetary medium. Ground-based Interplanetary Scintillation (IPS) observations are an important and effective method for measuring solar wind speed and the structures of small diameter radio sources. In this paper we will discuss the IPS observations in China.

Liu, Li-Jia; Peng, Bo

2013-07-01

358

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

359

Scintillation-Induced Intermittency in SETI  

Microsoft Academic Search

We consider interstellar scintillations as a cause of intermittency in radio\\u000asignals from extraterrestrial intelligence (ETI). We demonstrate that\\u000ascintillations are very likely to allow initial detections of narrowband\\u000asignals from distant sources (> 100 pc), while making redetections improbable.\\u000aWe consider three models in order to assess the non-repeating, narrowband\\u000aevents found in recent SETI and to analyze large

James M. Cordes; T. Joseph; W. Lazio

1997-01-01

360

Cerium-containing glasses for fast scintillators  

Microsoft Academic Search

Electromagnetic calorimetry requires fast and dense scintillators, such as CeF3. Glasses offer an attractive alternative because their synthesis is easier. Glass formation has been investigated in NaPO3–CeF3–MF2 (M=Zn, Cd, Ba, Pb) ternary systems. CeF3 concentration could reach 35 mol.%, but this content should be smaller to obtain large bulk samples free of crystals. The influence of composition on glass stability

Jia Jiang; Guoyin Zhang; Marcel Poulain

1998-01-01

361

Liquid-scintillation alpha-detection techniques  

Microsoft Academic Search

Accurate, quantitative determinations of alpha-emitting nuclides by conventional plate-counting methods are difficult because of sample self-absorption problems in counting and because of non-reproducible losses in conventional sample separation methods. Liquid scintillation alpha spectrometry offers an attractive with no sample self-absorption or geometry problems and with 100% counting efficiency. Sample preparation may include extraction of the alpha emitter of interest by

J. W. McKlveen; W. J. McDowell

1983-01-01

362

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

363

Forecasting scintillations, the CNOFS satellite challenge  

NASA Astrophysics Data System (ADS)

This paper describes the science issues associated with the Communication / Navigation Outage Forecasting System (C/NOFS) Mission of the Air Force Research Laboratory. The primary purpose of C/NOFS is to forecast ionospheric irregularities that adversely impact communication and navigation systems. A satellite, scheduled for launch in January 2004 into a low inclination (13^o), elliptical (˜400 × 700 km) orbit, is the main component of the C/NOFS Mission. Complementary ground-based measurements are also part of the Mission. Difficulties in predicting the presence of scintillation-producing irregularities may be organized into three categories: (1) understand physical processes active in the background ionosphere and thermosphere, in order to nowcast and forecast the equatorial ionosphere; (2) identify mechanisms that trigger or quench the plasma irregularities; and (3) determine how irregularity spectra evolve. C/NOFS is the first satellite solely dedicated to forecasting ionospheric irregularities and radio wave scintillations. Its sensors will measure the following parameters: ambient and fluctuating electron densities; ion and electron temperatures; AC and DC electric fields; magnetic fields; neutral winds; ionospheric scintillations; and electron content along the lines of sight between the C/NOFS and GPS satellites. Forecasting will be based on both ground and space data. Significant international participation in pursuing C/NOFS science goals is desired and anticipated.

de La Beaujardiere, O.; Retterer, J.; Groves, K.; Burke, W.; Rich, F.; Basu, B.; Decker, D.; Jeong, L.

2003-04-01

364

GPS scintillations over Vietnam on April 2006  

NASA Astrophysics Data System (ADS)

In Vietnam, at Hue (16.4°N, 107.6°E) and Hoc Mon (10.9°N, 106.6°E), are located two GPS receivers specially modified for recording, at a sampling rate of 50 Hz, the phase and the amplitude of the L1 signal and the Total Electron Content (TEC) from L1 and L2. In April 2006 both the receivers have observed post-sunset scintillation inhibition when moderate magnetic storms occurred. These measurements together with a 3D plus time imaging of the ionosphere produced by the Multi-Instrument Data Analysis System (MIDAS) have revealed interesting features that will be described in the present paper. In particular, the results confirm the role of the ring current on the generation of the equatorial F layer irregularities of scale size from less than a hundred meters to a few kilometers, highlighting also its important role in inhibiting scintillation during the storm. The characterization of the different conditions of the Interplanetary Magnetic Field (IMF) will be illustrated, as well, to attempt a description of the scintillation effects over a region scarcely investigated in the open literature.

Alfonsi, Lucilla; Spogli, Luca; Tong, Jenna R.; de Franceschi, Giorgiana; Romano, Vincenzo; Bourdillon, Alain; Le Huy, Minh; Mitchell, Cathryn N.

2010-05-01

365

Growth and characterization of strontium metaborate scintillators  

NASA Astrophysics Data System (ADS)

The undoped and 0.5% Ce3+-doped strontium metaborate SrB2O4 single crystals has been grown successfully by micro-pulling down method with radio frequency (RF) heating system, and scintillation characteristics including optical properties and radiation response were studied for these crystals. The Ce3+-doped SrB2O4 crystal showed absorption band around 240-320 nm, which is corresponding to the 4f-5d transition of Ce3+. Intense emission band at 375 nm due to the Ce3+ 5d-4f transition was observed under 241Am 5.5 MeV ?-ray excitation. The scintillation decay time showed fast (50 ns) and slow (1430 ns) components ascribed to the Ce3+ 5d-4f transition and lattice defect in the crystal, respectively. The scintillation light yield of Ce3+-doped SrB2O4 was calculated to be about 1000 ph/n under 252Cf irradiation.

Fujimoto, Yutaka; Yanagida, Takayuki; Yokota, Yuui; Kawaguchi, Noriaki; Fukuda, Kentaro; Totsuka, Daisuke; Watanabe, Kenichi; Yamazaki, Atsushi; Yoshikawa, Akira

2011-12-01

366

Theoretical solutions for particulate scintillation monitors  

NASA Astrophysics Data System (ADS)

Theoretical analysis for recently developed particulate scintillation monitoring technique is presented. The technique makes use of a light beam passing through a stack to the opposite detector. The detector measures not only the average light intensity, but also the temporal variation in the light intensity, which is different from conventional opacity systems. The significant advantage of scintillation monitors is their insensitivity to lens contamination. However, until now theories relevant to the technique have not been found in the literature. In this article, it is first assumed that the number of particles in a light beam passing through stack airflow is a Poisson random variable. Then, by use of Mie's theory and stochastic process theory, a mathematical model for output light intensity, the mathematical expectation and the variance of output light intensity are derived. Finally, an equation for calculating particulate mass concentration is obtained. Theoretical analysis shows that scintillation monitors are insensitive to lens contamination but dependent on particle size distribution. Experiments verified the theoretical results.

Chen, Anshi; Hao, Jiming; Zhou, Zhongping; Zu, Jing

1999-08-01

367

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

368

Liquid Scintillator Response at Low-Energy  

NASA Astrophysics Data System (ADS)

The brightest source of neutrinos in our solar system is the sun. Neutrinos from the sun are especially hard to detect because they arrive to the Earth with energies less than 15MeV. KamLAND, a sensitive one-kiloton liquid scintillator detector allocated in a deep underground mine in central Japan, is preparing to detect solar neutrinos. To do this we must better understand the detectors response at the low energy region. Low energy particles have a different response because when traveling inside liquid scintillator at low energies they have a lower probability of emitting Cherenkov light. It is important to understand the amount of energy produced from these Cherenkov emissions and how this will affect neutrino energy reconstruction. This group has built a high precision Compton Spectrometer designed to study the response of the KamLAND liquid scintillator to the Cherenkov light. The spectrometer has high precision amplitude and time measurements by a data acquisition system based on the VME standard of electronics. The analysis of this data will be important for the future use of the KamLAND detector in detecting solar neutrinos.

Passmore, Daniel

2005-04-01

369

New Scintillating Crystals for PET Scanners  

NASA Astrophysics Data System (ADS)

Systematic R&D on basic mechanism in inorganic scintillators, initiated by the Crystal Clear Collaboration at CERN 10 years ago, has contributed not to a small amount, to the development of new materials for a new generation of medical imaging devices with increased resolution and sensitivity. The first important requirement for a scintillator to be used in medical imaging devices is the stopping power for the given energy range of X and ? rays to be considered, and more precisely the conversion efficiency. A high light yield is also mandatory to improve the energy resolution, which is essentially limited by the photostatistics and the electronic noise at these energies. A short scintillation decay time allows to reduce the dead time and therefore to increase the limiting counting rate. When all these requirements are fulfilled the sensitivity and image contrast are increased for a given patient dose, or the dose can be reduced. Examples of new materials under development by the Crystal Clear Collaboration will be given with an emphasis on the major breakthrough they can bring in medical imaging, as compared to present equipments.

Lecoq, Paul

2002-01-01

370

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

371

Liquid-scintillation alpha-detection techniques  

SciTech Connect

Accurate, quantitative determinations of alpha-emitting nuclides by conventional plate-counting methods are difficult because of sample self-absorption problems in counting and because of non-reproducible losses in conventional sample separation methods. Liquid scintillation alpha spectrometry offers an attractive with no sample self-absorption or geometry problems and with 100% counting efficiency. Sample preparation may include extraction of the alpha emitter of interest by a specific organic-phase-soluble compound directly into the liquid scintillation counting medium. Detection electronics use energy and pulse-shape discrimination to yield alpha spectra without beta and gamma background interference. Specific procedures have been developed for gross alpha, uranium, plutonium, thorium, and polonium assay. Possibilities for a large number of other applications exist. Accuracy and reproducibility are typically in the 1% range. Backgrounds on the order of 0.01 cpm are readily achievable. The paper will present an overview of liquid scintillation alpha counting techniques and some of the results achieved for specific applications.

McKlveen, J.W.; McDowell, W.J.

1983-01-01

372

Ionospheric response to October 2003 storm through GPS scintillation data.  

NASA Astrophysics Data System (ADS)

Transionospheric radiowaves scintillation is caused by small-scale irregularities in the electron density distribution at E and F region altitudes. These small-scale irregularities have a turbulent spatial spectral behaviour and stem from different mechanisms at low and high magnetic latitudes. Using GPS derived scintillation information, an analysis on spatial and temporal distributions of small-scale plasma irregularities is carried out, during last October 2003 storm. GPS derived scintillation indices are pointed out by means of three GPS scintillation monitors located at Calgary, Yellowknife, and Athabasca (Canada). These monitors provide for intensity and phase scintillation indices as well as information on TEC and TEC fluctuations. Moreover, the relationship between small-scale irregularities producing scintillation and plasma irregularities responsible for TEC fluctuations is investigated, by means of some GPS geodetic receivers available in the same area. Here, preliminary results are presented and discussed.

Forte, B.; Skone, S.; Hoyle, V.

373

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

374

New scintillator: cerium-doped dense oxide glass  

NASA Astrophysics Data System (ADS)

The properties of high rare-earth-containing borosilicate glass have been investigated to assess the potential for using this material to construct electromagnetic calorimeters for particle physics. We report here on measurements of scintillation yield, transmission and decay time, on large blocks of Ce3+-doped Gd2O3-based glasses, the samples were excited by a high energy X-ray beam and the associated scintillation yield and decay time were measured. The optical transmission of the samples was measured. It was observed that scintillation yield of present scintillation glass is 10 - 20% of BGO scintillation yield, decay time is in range of 60 - 80 ns, glass density is 5.40 g/cm(superscript 3$. It was concluded that higher density and availability and low cost makes this glass become promising candidate for cerium doped dense scintillator.

Jiang, Chun; Zeng, Qingji; Gan, Fuxi

2000-10-01

375

Scintillation properties of cerium-doped germanate glass  

NASA Astrophysics Data System (ADS)

The properties of high rare-earth-containing germanate glass have been investigated to assess the potential for using this material to construct electromagnetic calorimeters for particle physics. We report here on measurements of scintillation yield, transmission and decay time, on large blocks of Ce3+-doped Gd2O3-based glasses, the samples were excited by a high energy X-ray beam and the associated scintillation yield and decay time was measured. The optical transmission of the samples was measured. It was observed that scintillation yield of present scintillation glass is 20 - 30% of BGO scintillation yield, decay time is in range of 60 - 90 ns, glass density is 5.75 g/cm3. It was concluded that higher density and availability and low cost make this glass become promising candidate for cerium doped dense scintillator.

Jiang, Chun; Zeng, Qingji; Gan, Fuxi

2000-11-01

376

Temperature Dependence of Scintillation Properties of Bright Oxide Scintillators for Well-Logging  

NASA Astrophysics Data System (ADS)

Scintillation characteristics such as the pulse height, energy resolution, and decay time of single crystals of Tl-doped NaI (Tl:NaI), Ce-doped Lu2SiO5 (Ce:LSO), Ce-doped YAlO3 (Ce:YAP), Ce-doped Gd3(Al,Ga)5O12 (Ce:GAGG), Pr-doped Lu3Al5O12 (Pr:LuAG), undoped LuAG, and Ce-doped Y3Al5O12 (Ce:YAG) transparent ceramics were compared at 25--150 °C to simulate well logging conditions. For increasing temperature, the light output of the scintillators decreased, mostly because of thermal quenching. Among these samples, Pr:LuAG demonstrated the highest scintillation performance at 150 °C.

Yanagida, Takayuki; Fujimoto, Yutaka; Kurosawa, Shunsuke; Kamada, Kei; Takahashi, Hiromitsu; Fukazawa, Yasushi; Nikl, Martin; Chani, Valery

2013-07-01

377

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

378

Properties of the high-density scintillator cerium fluoride  

Microsoft Academic Search

A new radiation-hard scintillator, CeFâ, has been found. It has a density of 6.16 g\\/cm³ and a radiation length of 1.7 cm. Two scintillation decay constants have been detected with time constants of approx. 2 ns and 31 ns peaking at 310 nm and 340 nm, respectively. The amount of scintillation light from our present samples is about 50% that

D. F. Anderson

1989-01-01

379

Systematic studies of small scintillators for new sampling calorimeter  

NASA Astrophysics Data System (ADS)

A new sampling calorimeter using very thin scintillators and the multi-pixel photon counter (MPPC) has been proposed to produce better position resolution for the international linear collider (ILC) experiment. As part of this R&D study, small plastic scintillators of different sizes, thickness and wrapping reflectors are systematically studied. The scintillation light due to beta rays from a collimated ^{90}Sr source are collected from the scintillator by wavelength-shifting (WLS) fiber and converted into electrical signals at the PMT. The wrapped scintillator that gives the best light yield is determined by comparing the measured pulse height of each 10 × 40 × 2 mm strip scintillator covered with 3M reflective mirror film, teflon, white paint, black tape, gold, aluminum and white paint+teflon. The pulse height dependence on position, length and thickness of the 3M reflective mirror film and teflon wrapped scintillators are measured. Results show that the 3M radiant mirror film-wrapped scintillator has the greatest light yield with an average of 9.2 photoelectrons. It is observed that light yield slightly increases with scintillator length, but increases to about 100% when WLS fiber diameter is increased from 1.0 mm to 1.6 mm. The position dependence measurement along the strip scintillator showed the uniformity of light transmission from the sensor to the PMT. A dip across the strip is observed which is 40% of the maximum pulse height. The block type scintillator pulse height, on the other hand, is found to be almost proportional to scintillator thickness.

Jacosalem, E. P.; Iba, S.; Nakajima, N.; Ono, H.; Sanchez, A. L. C.; Bacala, A. M.; Miyata, H.

2007-12-01

380

Systematic studies of small scintillators for new sampling calorimeter  

Microsoft Academic Search

A new sampling calorimeter using very thin scintillators and the multi-pixel photon counter (MPPC) has been proposed to produce\\u000a better position resolution for the international linear collider (ILC) experiment. As part of this R&D study, small plastic\\u000a scintillators of different sizes, thickness and wrapping reflectors are systematically studied. The scintillation light due\\u000a to beta rays from a collimated 90Sr source

E. P. Jacosalem; S. Iba; N. Nakajima; H. Ono; A. L. C. Sanchez; A. M. Bacala; H. Miyata

2007-01-01

381

Plastic scintillator with phosphorescent dopants for alpha-particles registration  

Microsoft Academic Search

In the present work we try to study the difference between the conventional scintillator and the scintillator with Eu-organic complexes in response to alpha-particle of 239Pu source. It is shown that polystyrene-based scintillator film with 4 wt% of Eu-organic complex have 5650 photons\\/MeV light output for alpha-particle of 5.4 MeV energy. This is 7 times higher than light output of

A. F. Adadurov; P. N. Zhmurin; V. N. Lebedev; V. V. Kovalenko

2010-01-01

382

Plastic scintillator with phosphorescent dopants for ?-particles registration  

Microsoft Academic Search

In the present work we try to study the difference between the conventional scintillator and the scintillator with Eu-organic complexes in response to ?-particle of 239Pu source. It is shown that polystyrene-based scintillator film with 4wt% of Eu-organic complex have 5650 photons\\/MeV light output for ?-particle of 5.4MeV energy. This is 7 times higher than light output of the conventional

A. F. Adadurov; P. N. Zhmurin; V. N. Lebedev; V. V. Kovalenko

2010-01-01

383

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

384

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

385

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

386

Energy response and reaction losses in plastic scintillators  

Microsoft Academic Search

The energy dependence of the scintillation response (light output) of plastic scintillator BC400 has been investigated for protons in the energy region of 60 to 220 MeV. In this region the scintillation exhibits a linear response, as well as a noticeable difference in the light output between stopping and passing-through (transmission) protons. A comparison between our results and theoretical calculations

Z. Papandreou; G. J. Lolos; G. M. Huber; J. C. Cormier; S. I. H. Naqvi; E. L. Mathie; D. F. Ottewell; P. L. Walden; G. Jones; R. P. Trelle; X. Aslanoglou; S. Orfanakos

1988-01-01

387

The use of energy information in plastic scintillator material  

Microsoft Academic Search

Plastic scintillator material is often used for gamma-ray detection in many applications due to its relatively good sensitivity\\u000a and cost-effectiveness compared to other detection materials. However, due to the dominant Compton scattering interaction\\u000a mechanism, full energy peaks are not observed in plastic scintillator spectra and isotopic identification is impossible. Typically\\u000a plastic scintillator detectors are solely gross count detectors. In some

James H. Ely; Kevin K. Anderson; Derrick J. Bates; Richard T. Kouzes; C. Lo Presti; Robert C. Runkle; Edward R. Siciliano; Dennis R. Weier

2008-01-01

388

Advanced Large Area Plastic Scintillator Project (ALPS): Final Report  

Microsoft Academic Search

The advanced Large-Area Plastic Scintillator (ALPS) Project at Pacific Northwest National Laboratory investigated possible technological avenues for substantially advancing the state-of-the-art in gamma-ray detection via large-area plastic scintillators. The three predominant themes of these investigations comprised the following: * Maximizing light collection efficiency from a single large-area sheet of plastic scintillator, and optimizing hardware event trigger definition to retain detection

David V. Jordan; Paul L. Reeder; Lindsay C. Todd; Glen A. Warren; Kathleen R. McCormick; Daniel L. Stephens; Bruce D. Geelhood; James M. Alzheimer; Shannon L. Crowell; William A. Sliger

2008-01-01

389

New scintillating media based on liquid crystals for particle detectors  

Microsoft Academic Search

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

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

2000-01-01

390

New scintillating media based on liquid crystals for particle detectors  

Microsoft Academic Search

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

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

2000-01-01

391

Silicon photodiodes as photomultiplier replacements in industrial scintillation counters  

Microsoft Academic Search

PIN silicon photodiodes used with low-noise preamplifiers are an attractive alternative to photomultipliers in some industrial scintillation counters. They are compact, robust, stable and insensitive to magnetic fields. A high-voltage supply is not required and the photodiode and preamplifier may be battery operated. The energy resolution of a scintillation counter comprising a 10*10*20 mm3 CsI (Tl) scintillator coupled to a

M. Asghar; D. C. Imrie

1989-01-01

392

Scintillating luminescence of cerium-doped dense oxide glass  

Microsoft Academic Search

New dense oxide glass scintillator has been discovered in the system: B2O3-SiO2-Al2O3- Gd2O3 doped with trivalence cerium. This scintillator has a unique combination of properties including high scintillating light output, high density and desirable emission wavelength, large radiation hardness, short radiation length, and easy to produce in large size and low price. Here we compare the properties with those of

Chun Jiang; Junzhou Zhang; Fu-Xi Gan

1999-01-01

393

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

394

Newborn Screening  

MedlinePLUS Videos and Cool Tools

... as poor growth or mental retardation, or even death. Newborn screening commonly may include either a blood ... Once diagnosed, treatment can save the baby from death or lifelong health problems. This reference summary explains ...

395

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

396

Report on radiation exposure of lead-scintillator stack  

SciTech Connect

A stack of lead and scintillator was placed in a neutral beam obtained from targeting 800 GeV protons. Small pieces of film containing radiochromic dye were placed adjacent to the layers of scintillator for the purpose of measuring the radiation dose to the scintillator. Our motivation was to calibrate the radiation dose obtainable in this manner for future tests of scintillator for SSC experiments and to relate dose to flux to check absolute normalization for calculations. We also observed several other radiation effects which should be considered for both damage and compensation in a calorimeter.

Underwood, D.G.

1990-11-08

397

Daytime equatorial VHF radiowave scintillations and sporadic-E layer  

NASA Astrophysics Data System (ADS)

Daytime VHF radiowave scintillations at Trivandrum are compared with the E-region irregularities at Kodaikanal. It is shown that daytime scintillations at Trivandrum are basically of two categories. One type of scintillations is associated with the q type of sporadic-E occurrence during normal electrojet condition and is weak with peak-to-peak fluctuations of 1-2 dB. The other type of scintillations is associated with blanketing type of sporadic-E occurrence during counter electrojet condition with magnitude greater than 5 dB.

Koparkar, P. V.; Rastogi, R. G.; Sastri, J. H.

1989-08-01

398

Portable screen  

US Patent & Trademark Office Database

A portable privacy screen is provided, which enables a user to quickly and easily create a zone of personal space where cosmetics may be applied, clothes put on and adjusted, and changes and improvements in appearance made. The screen is constructed from a plurality of individual, smaller panels and is foldable into a compact and easily carried configuration. The screen may also have a mirror and can carry advertising messages or other printing. The portable screen is arranged in the general form of a triptych, preferably including an upper and a lower array of panels. Each individual array is also in the general form of a triptych. A carrying bag, which is dimensioned to snugly contain the portable screen in disassembled form and itself is sufficiently configured to be carried over the shoulder of a user like a duffle bag, is also provided. The lower array, is reversibly interconnected to the upper array and is held in spaced-apart relation therefrom. The privacy screen further includes at least one preferably battery powered fluorescent light removably attached by hook and loop fastener to the front surface of the central upper panel, at least one mirror, and support members for hanging various articles such as clothes therefrom.

Fremont; Donna A. (Port Orange, FL)

2001-09-25

399

Internet Guide  

NSDL National Science Digital Library

The Internet Guide is a no-nonsense site intended for Internet newbies. It consists of several short articles that discuss the basics of Internet navigation, common terms and phrases, Netiquette, and much more. Some specific technologies are also mentioned, such as Telnet and newsgroups. The Guide occasionally refers to various products or services; however, it does not endorse any particular company, instead offering a list of several potential choices. A particularly enlightening section defines twelve common Internet error messages, which are often confusing to both novices and seasoned users.

2002-01-01

400

HF produced ionospheric electron density irregularities diagnosed by UHF radio star scintillations  

SciTech Connect

HF-waves incident on an overdense (HF-frequency < penetration frequency) ionosphere are known to produce large scale electron density irregularities. It is predicted that similar irregularities are formed during underdense HF-modification. The propagation of UHF radio waves originating from radio stars will be affected by such irregularities in the ionosphere. The interest in a scintillation experiment is twofold. One may obtain information on the electron density irregularies and one may learn about the propagation of radio waves through such a perturbed medium. A thin screen (diffractive) theory is derived which allows to draw conclusons on the electron density irregularities from the intensity fluctuations measured on the ground if the phase perturbations are much less than one radian. Since radio stars suitable for scintillation measurements at UHF are very faint an antenna with a large collection area is required. The observations reported in this dissertation were performed with the 300m diameter spherical reflector of the Arecibo Observatory. Successful observations were performed at 430 MHz and at 1400 MHz. Intensity fluctuations at such high frequencies measured with a large antenna suffer severe filtering in the thin phase screen regime. The theory presented in this dissertation includes these filtering effects. Many observations agree with the predictions of that theory. Some observations indicate that refraction effects have to be included to explain the data. HF-induced electron density irregularities were only observed during overdense heating.

Alfred, F.

1982-01-01

401

A radio wave scattering algorithm and irregularity model for scintillation predictions  

NASA Astrophysics Data System (ADS)

An algorithm for calculations of phase and amplitude scintillation of satellite signals in the equatorial region will be described in detail. The algorithm will be developed by initially transforming the discrete version of the Huygens-Fresnel integral into a convolution involving a series of coefficients with decreasing amplitudes. Next, the Fourier transform of the corresponding series of coefficients is stored for all the frequencies of interest, and the fast Fourier transform algorithm is used to evaluate discrete convolutions. Two phase screen models will be described. The first assumes that the phase fluctuations of the wave front emerging from the bottom of the irregularity layer are proportional to electron density fluctuations directly obtained from satellite in situ measurements. The second assumes that the same phase fluctuations can be obtained from their power spectral densities and phase spectra, represented by analytical functions with parameters provided by physics-based or morphological models of ionospheric irregularities. The propagation algorithm will be applied to both phase screen models, assuming five frequencies in the high-VHF to low-SHF band (suffering strong to weak scattering), to display its potential in the prediction of phase and amplitude scintillation of satellite signals.

Costa, Emanoel; Basu, Santimay

2002-06-01

402

Medication Guide  

Center for Drug Evaluation (CDER)

Text VersionPage 1. DX-88 (ecallantide) 27 November 2009 1. I 4.1.3 Draft Label - KALBITOR Medication Guide KALBITOR&J (KAL-bi-tor) ( ecallan tide) ... More results from www.fda.gov/downloads/drugs/drugsafety

403

Coatings Guide  

EPA Science Inventory

The Coatings Guide is a free online information resource that focuses on alternative, low-emission coatings for metal, plastic, and architectural substrates. Developed cooperatively by the U.S. EPA's Office of Research and Development and Research Triangle Institute (RTI) Interna...

404

Homebuyer's Guide.  

ERIC Educational Resources Information Center

Designed to assist prospective buyers in making such important decisions as whether to buy a new or older home and within what price range, the guide provides information on the purchase process. Discussion of the purchase process covers the life-cycle costs (recurring homeownership costs that must be met every month); selection of a home;…

Sindt, Roger P.; Harris, Jack

405

Teachers Guide.  

ERIC Educational Resources Information Center

This guide provides teachers with copies of the materials given to students participating in the oceanography program of the Orange County Floating Laboratory Program and provides information concerning colleges and universities offering courses in oceanography and marine science, source of films, and sources of publications concerning the Navy's…

Linsky, Ronald B.; Schnitger, Ronald L.

406

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

407

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; Wisniewski, D.; Wojtowicz, A.J. [Boston Univ., MA (United States). Dept. of Chemistry]|[N. Copernicus Univ., Torun (Poland). Inst. of Physics; Zych, E. [Boston Univ., MA (United States)]|[Wroclaw Univ. (Poland). Dept. of Chemistry

1996-06-01

408

Multiimage formatting: effect on scintillation image quality  

SciTech Connect

Multiimage formatters designed for use with scintillation cameras allow convenient presentation of as many as 90 images on a single film. Three different multiimagers (Searle Microdot 3132, Toshiba Gamma Imager GMI-04A, and Matrix Multi-imager 4) were evaluated with phantoms. Image quality was not equivalent in all positions on the resultant film, and was unacceptable in some cases. Individual laboratories should be aware of the potential loss of diagnostic information when using multiimage formatters and should evaluate their devices for this potential problem.

Fajman, W.A.; Sarper, R.

1982-10-01

409

Scintillator quenching effects observed in the AMS-1 TOF data  

NASA Astrophysics Data System (ADS)

An analytical expression for the light output response of plastic scintillators as a function of the energy and the z identity of the incident ion is proposed. The effect of the ? rays is considered in the calculation of the scintillation efficiency. .

Esquivel, O.; Reyes, T.; Menchaca-Rocha, A.

2001-05-01

410

A Model of Nuclear Recoil Scintillation Efficiency in Noble Liquids  

NASA Astrophysics Data System (ADS)

Scintillation efficiency of low-energy nuclear recoils in noble liquids plays a crucial role in interpreting results from some direct searches for Weakly Interacting Massive Particle (WIMP) dark matter. However, the cause of a reduced scintillation efficiency relative to electronic recoils in noble liquids remains unclear at the moment. We attribute such a reduction of scintillation efficiency to two major mechanisms: 1) energy loss and 2) scintillation quenching. The former is commonly described by Lindhard's theory and the latter by Birk's saturation law. We propose to combine these two to explain the observed reduction of scintillation yield for nuclear recoils in noble liquids. Birk's constants kB for argon, neon and xenon determined from existing data are used to predict noble liquid scintillator's response to low-energy nuclear recoils and low-energy electrons. We find that energy loss due to nuclear stopping power that contributes little to ionization and excitation is the dominant reduction mechanism in scintillation efficiency for nuclear recoils, but that significant additional quenching results from the nonlinear response of scintillation to the ionization density.

Mei, Dongming; Yin, Zhongbao; Stonehill, Laura; Hime, Andrew

2008-10-01

411

A model of nuclear recoil scintillation efficiency in noble liquids  

NASA Astrophysics Data System (ADS)

Scintillation efficiency of low-energy nuclear recoils in noble liquids plays a crucial role in interpreting results from some direct searches for weakly interacting massive particle (WIMP) dark matter. However, the cause of a reduced scintillation efficiency relative to electronic recoils in noble liquids remains unclear at the moment. We attribute such a reduction of scintillation efficiency to two major mechanisms: (1) energy loss and (2) scintillation quenching. The former is commonly described by Lindhard's theory and the latter by Birk's saturation law. We propose to combine these two to explain the observed reduction of scintillation yield for nuclear recoils in noble liquids. Birk's constants kB for argon, neon and xenon determined from experimental data are used to predict noble liquid scintillator's response to low-energy nuclear recoils and low-energy electrons. We find that energy loss due to nuclear stopping power that contributes little to ionization and excitation is the dominant reduction mechanism in scintillation efficiency for nuclear recoils, but that significant additional quenching results from the nonlinear response of scintillation to the ionization density.

Mei, D.-M.; Yin, Z.-B.; Stonehill, L. C.; Hime, A.

2008-08-01

412

Light transport contribution to the timing characteristics of scintillation detectors  

Microsoft Academic Search

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

N. Ghal-Eh

2011-01-01

413

On the necessity of light transport simulation in scintillators  

Microsoft Academic Search

In this study, the light transport simulation in scintillators is introduced, the wavelength-dependencies in the process are taken into account, the effect of different shapes\\/lengths of lightguides on the response of the scintillation detectors are investigated and finally the need for such a simulation in addition to the particle transport simulation in a perfect response function predicting code is explained.

N. Ghaleh; G. R. Etaati

2009-01-01

414

Total-Absorption Scintillation Counter for High-Energy Photons  

Microsoft Academic Search

A total-absorption scintillation counter for high-energy photons is ; developed with plus or minus % energy spread for 130-Mev photons. The counter ; is built of enough plastic scintillator to contain most of the energy and ; maintain a high detection efficiency. The technique of observing a statistical ; sampling of light from an integrating volume is used. The integrating

William C. Bowman; Jim B. Carroll; John A. Poirier

1962-01-01

415

Dual scintillation detector for determining grade of uranium ore  

Microsoft Academic Search

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

R. Brown; P. A. Proulx

1981-01-01

416

Polysilylene copolymers for ultrafast scintillator applications. 2. Thin film formulations  

Microsoft Academic Search

Ultrafast scintillator fluors based on poly(silylene) copolymers have been developed in our laboratory for use in fast counting applications. The absorption and fluorescence spectra of this copolymer are quite sharp compared with most aromatic fluors and result in severe reabsorption problems. This reabsorption limits the usefulness of these materials in typical host solvents for liquid or plastic scintillator formulations. However,

Jan-Michael Gosau; Larry A Harrah; Andrea E Hoyt

2001-01-01

417

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

418

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

419

Gadolinium loaded plastic scintillators for high efficiency neutron detection  

Microsoft Academic Search

Gadolinium has the highest thermal neutron absorption cross section of any naturally occurring element, and emits conversion electrons as well as atomic X-rays in over 50% of its neutron captures, which makes it a useful dopant in scintillators for detecting thermal neutrons. Gadolinium isopropoxide was studied as a possible dopant for styrene-based plastic scintillators as a convenient and inexpensive method

Lena Ovechkina; Kent Riley; Stuart Miller; Zane Bell; Vivek Nagarkar

2009-01-01

420

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

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

2003-01-01

421

Investigation of Plastic Scintillator Detector Configurations for Neutron Studies  

Microsoft Academic Search

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

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

2007-01-01

422

Fission fragment response characteristics of thin film plastic scintillators  

Microsoft Academic Search

Results are presented of measurements of the energy loss response of thin film plastic scintillators using fission fragments for a range of film thicknesses from 0.8 to 6 mum. Previously reported anomalous response behaviour of the thin film plastic scintillators of 4-5 mum thickness was not observed. The improved understanding of the light response characteristics of TFPS makes possible their

C. B. Franklyn

1988-01-01

423

New scintillation materials for fiber tracking and calorimetry  

Microsoft Academic Search

Radiation damage studies were performed on new polystyrene-based plastic scintillators. Several samples of different multicomponent systems containing new fluorescent compounds were irradiated with a 60Co source to a 10 Mrad dose. After irradiation, the samples were annealed for ten days in oxygen and three days in air. Scintillation light output, fluorescence, and transmittance spectra were recorded at three different stages;

A. D. Bross; A. Pla-Dalmau; B. Baumbaugh; J. Godfrey; J. Jacques; J. Marchant; J. Piekarz; R. Ruchti

1991-01-01

424

Modeling and Optimization of Scintillator Arrays for PET Detectors  

Microsoft Academic Search

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

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

2010-01-01

425

GPS receiver performance characterization under realistic ionospheric phase scintillation environments  

Microsoft Academic Search

It is well known that ionospheric scintillation has the potential to affect all types of GPS receivers, even dual-frequency military precise-positioning service versions. In a previous effort the degree of degradation to Wide Area Augmentation System (WAAS) operation caused by scintillation, on the basis of simulated data input to an actual WAAS reference receiver under carefully controlled laboratory conditions at

Thomas N. Morrissey; Karl W. Shallberg; A. J. Van Dierendonck; Matthew J. Nicholson

2004-01-01

426

Present status in the field of precision liquid scintillation counting  

Microsoft Academic Search

First, a short review of some general aspects, e.g., basic mechanisms, ; scintillators, instrumental developments, and source preparation is given. Then, ; the applicability and the attainable accuracy of the liquid scintillation method ; for absolute measurements of the activity of BETA -emitters of different energy, ; alpha -emitters, and EC-nuclides are discussed. The different techniques used ; are described:

R. Vaninbroukx; I. Stanef

1973-01-01

427

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

428

Mechanical deformation effect on CsI(Tl) scintillators efficiency  

Microsoft Academic Search

Due to the technological limitations in scintillation crystal growth and machining afterwards, crystals always contain certain internal defects and nonuniform distribution of intrinsic stresses. This work is directed to study the effect of CsI(Tl) mechanical deformation on their scintillation efficiency. It is shown that light output changes depend on the type of deformation (shock, steady deformation) and crystallographic orientation of

V. Gayshan; A. Boyarintsev; A. Gektin; D. Zosim

2003-01-01

429

Timing resolution of 'Shisk-Kebab' lead scintillator sandwich calorimeters.  

National Technical Information Service (NTIS)

We have constructed lead scintillator sandwich calorimeters with 1/4 (chi)(sub o) sampling frequency and total thickness (approximately)16(chi)(sub o). The 4 mm thick scintillator plates are read out by wavelength shifter fibers 1 mm in diameter which pas...

E. Kistenev S. White Y. Pischalnikov Y. Protopopov V. Rykalin

1992-01-01

430

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

431

A high resolution scintillating fiber gamma-ray telescope.  

NASA Astrophysics Data System (ADS)

Scintillating fibers coupled to position sensitive photomultipliers have good angular precision and good energy resolution in detecting gamma-rays. Scintillating fibers stacked up into scintillating fiber planes U, V and W that are rotated by 60° angle relative to each other and coupled to position sensitive photomultipliers can be used as high resolution imaging gamma-ray detectors. With this arrangement the Compton electron or pair production point can be determined by the scintillation photons reaching the photomultipliers. A 3-dimensional conversion point accuracy is expected to be ?rms ? 1 mm. The authors are presenting the design of a large area gamma-ray detector with high angular and energy resolution for space based experiments, using scintillating fibers and recently developed position sensitive photomultiplier tubes.

Atac, M.; Cline, D. B.; Park, J.; Fenyves, E. J.; Chaney, R. C.; Hammack, H.

432

Turbulence profiles from the scintillation of Stars, Planets, and Moon  

NASA Astrophysics Data System (ADS)

Atmospheric turbulence can be characterized by the scintillation of astronomical sources. The physics of weak and strong scintillation is briefly recalled. The Multi-Aperture Scintillation Sensor, MASS, uses spatial properties of the scintillation produced by single stars to reconstruct low-resolution turbulence profiles. A description of the combined MASS-DIMM instrument is given and the accuracy of this method is evaluated. By replacing a single star with a planet, we can sense turbulence at few hundred meters above the site, and such an experiment is described. However, of greater importance is to measure the turbulence in the immediate vicinity of a telescope or site monitor. Here, lunar scintillation is the method of choice. A simple lunar scintillometer, LuSci, is under development at CTIO. A new method to interpred its data and the results of first tests are presented.

Tokovinin, A.

2007-10-01

433

Analysis of GPS ionospheric scintillation measurements at high latitudes  

NASA Astrophysics Data System (ADS)

Transionospheric radio signals may experience fluctuations in their amplitude and phase due to irregularity in the spatial electron density distribution, referred to as scintillation. Ionospheric scintillation is responsible for transionospheric signal degradation that can affect the performance of satellite based navigation systems. Usually, the scintillation activity is measured by means of indices such as the normalised standard deviation of the received intensity and the standard deviation of the received phase. Statistical analyses on the use of an additional index are carried out based on 50 Hz GPS measurements recorded at Dirigibile Italia Station (Ny-Alesund, Svalbard). The usefulness of such an additional parameter for the characterization of the phase scintillation activity is discussed and advanced. Also, the understanding of the signal dynamics due to ionospheric electron density irregularities is attempted by using such a new estimate for the phase scintillation.

Forte, B.; Materassi, M.; Alfonsi, L.; Romano, V.; Spalla, P.; de Franceschi, G.

2009-04-01

434

Ionospheric scintillations by sporadic-E irregularities over low latitude  

NASA Astrophysics Data System (ADS)

The observations of daytime ionospheric scintillation are attributed to E-region irregularities at high and equatorial latitudes. In this paper, VHF amplitude scintillations recorded during the daytime period from 1991 to 1999 at low latitude station Varanasi (geomag. lat. = 14° 55' N, long. = 154^0 E) are analyzed to study the behaviour of sporadic-E irregularities during the active solar and magnetic periods. The daytime digital scintillation data have been analyzed to study some important parameters of scintillation producing sporadic-E irregularities like auto-correlation function, power spectral densities, signal de-correlation time etc. We report the behaviour of these parameters under weak and strong scintillation conditions. The results are also discussed in the light of recent works.

Patel, Kalpana; Singh, A. K.; Patel, R. P.; Singh, R. P.

2007-12-01

435

Investigation of the effect of the scintillator material on the overall X-ray detection system performance by application of analytical models  

NASA Astrophysics Data System (ADS)

The purpose of the present work was to model a modern X-ray detection system and to investigate the effect of the scintillator material on the detector's output signal. The scintillators were used in the form of screens. The parameters investigated were the Modulation Transfer Function (MTF), the Detective Quantum Efficiency (DQE) and the Energy Absorption Efficiency (EAE). The results for some well-known scintillators (Y3Al5O12:Ce, Y2O3:Eu, ZnSCdS:Ag, Lu3Al5O7, CdWO4) are presented. Typical radiographic conditions were considered as input parameters. For simulation purposes, the intrinsic conversion efficiency (?c), the total number of optical photons produced per incident X-ray (m0), the attenuation coefficients and other optical parameters of the scintillator materials, were taken as input data. The complete simulation procedure was performed in a specially designed Graphical User Interface (GUI). The results showed that the Y2O3:Eu scintillator presented similar behavior to that of ZnSCdS:Ag, exhibiting higher DQE at zero spatial frequencies. For higher frequencies, however, the DQE values of Lu3Al5O7 and CdWO4 prevailed.

Efthimiou, N.; Kalivas, N.; Patatoukas, G.; Konstantinidis, A.; Valais, I.; Nikolopoulos, D.; Gaitanis, A.; David, S.; Michail, C.; Loudos, G.; Cavouras, D.; Panayiotakis, G.; Kandarakis, I.

2007-02-01

436

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

437

Genetic screening.  

PubMed

The family planning nurse practitioner may be the client's only link to genetic screening, education, and counseling. The principles of genetics, the types of genetic defects and their causes are presented. Clients at risk and the nurse practitioner's role in providing education, support, counseling, and referrals are discussed. PMID:6562263

Worthington, S

438

Laser Screen.  

National Technical Information Service (NTIS)

The patent describes a light screen device for measuring the velocity of a projectile, comprising a laser disposed opposite to one end of a first plane reflecting mirror and inclined with respect thereto to cause a laser beam to strike the first plane ref...

J. Kuchmas G. E. Bubb

1978-01-01

439

Spin Screening.  

National Technical Information Service (NTIS)

It is shown that the flavor singlet contribution of the constituents of the nucleon to the first moment of the spin structure function is suppressed in the deep inelastic limit, due to a nonperturbative screening mechanism catalyzed by the axial anomaly. ...

R. D. Ball

1991-01-01

440

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

441

The dependence of the energy resolution of gas proportional scintillation counters on the scintillation region to photomultiplier distance  

Microsoft Academic Search

The energy resolution for broad X-ray beams of gas proportional scintillation counters with medium to large size windows, parallel grids and no focusing system is discussed. The variation of the pulse amplitude with the radial distance is calculated for several distances d taken from the bottom of the scintillation region to the photomultiplier's photocathode (in the 0 to 50 mm

J. M. F. Dos Santos; A. C. S. S. M. Bento; C. A. N. Conde

1992-01-01

442

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

NASA Astrophysics Data System (ADS)

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

Jing, Tao

1995-01-01

443

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

PubMed

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

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

1998-10-01

444

Lanthanum halide scintillators: Properties and applications  

NASA Astrophysics Data System (ADS)

BrilLanCe®-350 and BrilLanCe®-380, Saint-Gobain Crystals’ trade-names for LaCl3:Ce and LaBr3:Ce are being brought to market under exclusive license to Delft and Bern Universities. We are reporting the properties of crystals produced with commercially viable processes and find they match others’ observations. These scintillators are bright (60,000 photons/MeV for LaBr3:Ce) and have very linear response, a combination that leads to very good energy resolution (<3% at 662 keV and about 6% at 122 keV for LaBr3:Ce). The materials also have fast scintillation decay times (<30 ns) which supports counting applications at very high rate. These fast light output properties also lead to very fast timing (<300 ps coincidence resolving time on 30 mm long pieces of LaBr3:Ce). These excellent properties are retained at high temperature with only moderate light loss (<10%) at 175 °C in both materials. The detectors carry natural background in La138 and Ac227, the latter having been substantially reduced in recent processing. BrilLanCe®-350 is now available in detectors up to 51 mm diameter while 38 mm diameter is available for BrilLanCe®-380. Larger sizes are expected.

Iltis, Alain; Mayhugh, M. R.; Menge, P.; Rozsa, C. M.; Selles, O.; Solovyev, V.

2006-07-01

445

Characterization of cerium fluoride nanocomposite scintillators  

SciTech Connect

Measurement of the neutron capture cross-sections of a number of short-lived isotopes would advance both pure and applied scientific research. These cross-sections are needed for calculation of criticality and waste production estimates for the Advanced Fuel Cycle Initiative, for analysis of data from nuclear weapons tests, and to improve understanding of nucleosynthesis. However, measurement of these cross-sections would require a detector with a faster signal decay time than those used in existing neutron capture experiments. Crystals of faster detector materials are not available in sufficient sizes and quantities to supply these large-scale experiments. Instead, we propose to use nanocomposite detectors, consisting of nanoscale particles of a scintillating material dispersed in a matrix material. We have successfully fabricated cerium fluoride (CeF{sub 3}) nanoparticles and dispersed them in a liquid matrix. We have characterized this scintillator and have measured its response to neutron capture. Results of the optical, structural, and radiation characterization will be presented.

Stange, Sy [Los Alamos National Laboratory; Esch, Ernst I [Los Alamos National Laboratory; Brown, Leif O [Los Alamos National Laboratory; Couture, Aaron J [Los Alamos National Laboratory; Mckigney, Edward A [Los Alamos National Laboratory; Muenchausen, Ross E [Los Alamos National Laboratory; Del Sesto, Rico E [Los Alamos National Laboratory; Gilbertson, Robert D [Los Alamos National Laboratory; Mccleskey, T Mark [Los Alamos National Laboratory; Reifarth, Rene [Los Alamos National Laboratory

2009-01-01

446

Imaging of gamma emitters using scintillation cameras  

NASA Astrophysics Data System (ADS)

Since their introduction by Hal Anger in the late 1950s, the gamma cameras have been widely used in the field of nuclear medicine. The original concept is based on the association of a large field of view scintillator optically coupled with an array of photomultiplier tubes (PMTs), in order to locate the position of interactions inside the crystal. Using a dedicated accessory, like a parallel hole collimator, to focus the field of view toward a predefined direction, it is possible to built up an image of the radioactive distribution. In terms of imaging performances, three main characteristics are commonly considered: uniformity, spatial resolution and energy resolution. Major improvements were mainly due to progress in terms of industrial process regarding analogical electronic, crystal growing or PMTs manufacturing. Today's gamma camera is highly digital, from the PMTs to the display. All the corrections are applied ``on the fly'' using up to date signal processing techniques. At the same time some significant progresses have been achieved in the field of collimators. Finally, two new technologies have been implemented, solid detectors like CdTe or CdZnTe, and pixellized scintillators plus photodiodes or position sensitive photomultiplier tubes. These solutions are particularly well adapted to build dedicated gamma camera for breast or intraoperative imaging.

Ricard, Marcel

2004-07-01

447

Scintillating Bolometers for Double Beta Decay Search  

NASA Astrophysics Data System (ADS)

In the field of Double Beta Decay searches the possibility to have high resolution detectors in which a very large part of the natural background can be discriminated with respect to the tiny expected signal, results very appealing. This very interesting possibility can be fulfilled in the case of a scintillating crystal bolometer containing a DBD emitter whose transition energy exceeds the one of the natural 2615 keV gamma line of 208Tl. We present the results achieved in the development of bolometric light detectors for double beta searches. The detectors are 1 mm thick germanium disk coated with a layer of SiO2 in order to increase the light collection. The adopted temperature sensors are NTD Ge thermistors optimized to work at temperatures between 9 and 13 mK. A light detector with a considerable large area (35 cm2) was constructed and run in a test measurement. A 140 g CdWO4 crystal (116Cd has a DBD transition energy of 2802 keV) was operated as bolometer and the scintillation light was read by the light detector. The excellent results combined with extreme easy light detector assembly represent the first tangible proof demonstrating the feasibility of this kind of technique.

Gorla, P.; Arnaboldi, C.; Beeman, J.; Capelli, S.; Giachero, A.; Gironi, L.; Pavan, M.; Pessina, G.; Pirro, S.; Previtali, E.

2008-05-01

448

The scintillating optical fiber calorimeter (SOFCAL) instrument  

NASA Astrophysics Data System (ADS)

A hybrid detector system is being developed for measuring the cosmic ray elemental composition and energy spectra above approximately GeV/nucleon. This system employs both a conventional 'passive' emulsion chamber and an 'active' ionization calorimeter incorporating scintillating fibers. Emulsion chambers have a proton energy threshold approximately greater than 5 TeV for detectable dark spots in the x-ray films which are used as a visual 'trigger.' The central element of this hybrid system is a calorimeter which has 10 x-y hodoscopic layers of 0.5 mm scintillating fibers interspersed with 4 mm lead plates. The fibers sample the hadronic and electromagnetic showers (cascades) initiated by interactions in the overlying emulsion chamber. The cascades are recorded by two image-intensified charge-coupled device (CCD) cameras which view the ends of the fibers to present orthogonal views. These showers are located and traced with microscopes in the emulsion chamber to provide an energy calibration through standard emulsion chamber methods, and an independent confirmation of the primary particle's charge (which is also measured with a Cerenkov counter above the emulsion chamber). The hybrid system will be used this fall for a balloon-borne measurement of the cosmic ray proton and helium spectra from approximately 400 GeV/n to approximately 10 TeV/n. An 8-hour test flight was performed in September 1995. Details of the detector system and sample results from the test flight are presented.

Christl, Mark J.; Fountain, W. F.; Parnell, Thomas A.; Roberts, F. E.; Benson, C.; Berry, Fred A.; Gregory, J. C.; Takahashi, Yoshiyuki

1996-10-01

449

Risk Perceptions Among Participants Undergoing Lung Cancer Screening: Baseline Results from the National Lung Screening Trial  

Microsoft Academic Search

Background  Lung cancer screening could present a “teachable moment” for promoting smoking cessation and relapse prevention. Understanding\\u000a the risk perceptions of older individuals who undergo screening will guide these efforts.\\u000a \\u000a \\u000a \\u000a Purpose  This paper examines National Lung Screening Trial (NLST) participants' perceptions of risk for lung cancer and other smoking-related\\u000a diseases. We investigated (1) whether risk perceptions of lung cancer screening participants differed

Elyse R. Park; Jamie S. Ostroff; William Rakowski; Ilana F. Gareen; Michael A. Diefenbach; Sandra Feibelmann; Nancy A. Rigotti

2009-01-01

450

Cytomegalovirus in pregnancy: to screen or not to screen  

PubMed Central

Background Cytomegalovirus (CMV) infection is now the commonest congenital form of infective neurological handicap, recognized by the Institute of Medicine as the leading priority for the developed world in congenital infection. In the absence of an effective vaccine, universal screening for CMV in pregnancy has been proposed, in order that primary infection could be diagnosed and- potentially- the burden of disability due to congenital CMV prevented. Discussion Universal screening for CMV to identify seronegative women at the beginning of pregnancy could potentially reduce the burden of congenital CMV in one of three ways. The risk of acquiring the infection during pregnancy has been shown to be reduced by institution of simple hygiene measures (primary prevention). Among women who seroconvert during pregnancy, CMV hyperimmune globulin (CMV HIG) shows promise in reducing the risk of perinatal transmission (secondary prevention), and CMV HIG and/ or antivirals may be effective in reducing the risk of clinical sequelae among those known to be infected (tertiary prevention). The reports from these studies have re-ignited interest in universal screening for CMV, but against the potential benefit of these exciting therapies needs to be weighed the challenges associated with the implementation of any universal screening in pregnancy. These include; the optimal test, and timing of screening, to maximize detection; an approach to the management of equivocal results, and the cost effectiveness of the proposed screening program. In this article, we provide an overview of current knowledge and ongoing trials in the prevention, diagnosis and management of congenital CMV. Recognising that CMV screening is already being offered to many patients on an ad hoc basis, we also provide a management algorithm to guide clinicians and assist in counseling patients. Summary We suggest that- on the basis of current data- the criteria necessary to recommend universal screening for CMV are not yet met, but this position is likely to change if trials currently underway confirm that CMV HIG and/ or antivirals are effective in reducing the burden of congenital CMV disease.

2013-01-01

451

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

452

Fiscal Officer Training, 1999-2000. Participant's Guide.  

ERIC Educational Resources Information Center

|This guide is intended for use by participants (college fiscal officers, business officers, bursars, loan managers, etc.) in a two-day workshop on Title IV of the reauthorized Higher Education Act. The guide includes copies of the visual displays used in the workshop, space for individual notes, sample forms, sample computer screens, quizzes, and…

Department of Education, Washington, DC.

453

Some features of ionizing radiation energy losses in organic polycrystalline and composite scintillators  

Microsoft Academic Search

New types of organic scintillators (polycrystals and composite scintillators) have been developed and compared with organic single crystals. Polycrystals and composite scintillators were prepared from different grain size fractions obtained by grinding a single crystal with high structural perfection at low temperature followed by sieving. Composite scintillators were prepared by adding specific grain size fractions of stilbene to an optically

Nikolai Z. Galunov; Natalya L. Karavaeva; Jong Kyung Kim; Yong Kyun Kim; Oleg A. Tarasenko; Eugenia V. Martynenko; Sergey V. Budakovsky

2007-01-01

454

Absolute Scintillation Yields in Liquid Argon and Xenon for Various Particles  

Microsoft Academic Search

For the determination of the absolute scintillation yields ---the number of scintillation photons per unit absorbed energy--- for a variety of particles in liquid argon, a series of simultaneous ionization and scintillation measurements were performed. The results verified that scintillation yields for relativistic heavy particles from Ne to La are constant despite their extensive range of linear energy transfer. Such

Tadayoshi Doke; Akira Hitachi; Jun Kikuchi; Kimiaki Masuda; Hiroyuki Okada; Eido Shibamura

2002-01-01

455

Newborn Screening  

NSDL National Science Digital Library

There's been a lot of talk recently about national testing standards for students. But now, some doctors are calling for national testing standards for newborns. In some states, every newborn baby gets a blood test that can detect more than thirty serious diseases. But in other states, it's a very different story. According to geneticist Piero Rinaldo of the Mayo Clinic, just having a state senator with an affected child could make the difference. Now, he and dozens of other experts have developed uniform standards for newborn screening. And they're calling on the federal government to adopt them. This Science update details many of the obstacles by which individual states and the U.S. government face when challenged with newborn screening practices. Additional links for further inquiry are provided.

American Association for the Advancement of Science (;)

2005-03-07

456

Scintillations of partially coherent multiple Gaussian beams in turbulence.  

PubMed

For an incidence composed of partially coherent multiple Gaussian beams, Huygens-Fresnel principle-based on-axis scintillation index is formulated in a weakly turbulent homogeneous horizontal atmospheric path. Our general formulation is applied to two examples of partially coherent annular and partially coherent flat-topped Gaussian beams. Compared to partially coherent single Gaussian beam scintillations, annular beam scintillations seem to possess higher values for all partial coherence levels, whereas flat-topped Gaussian beam intensity fluctuations are slightly larger, especially at lower coherence levels and at larger source sizes. At the same source partial coherence, annular beams exhibit smaller scintillations for larger ring sizes. For flat-topped Gaussian beams, except for very small and very large source sizes, as the number of Gaussian beams forming the flatness increases, intensity fluctuations also increase, a trend applicable for different degrees of coherence. A trend valid for both single and multiple Gaussian incidence, except for certain annular beams of large primary beam sizes, is that the scintillations decrease as the source becomes less coherent. Being applicable for all degrees of source coherences, for both beams examined, scintillations increase steadily as the Rytov plane wave scintillation index increases. PMID:19340150

Baykal, Yahya; Eyyubo?lu, Halil T; Cai, Yangjian

2009-04-01

457

Novel polysiloxane-based scintillators for neutron detection.  

PubMed

Polysiloxane-based scintillators are promising for employment in harsh environments, owing to their outstanding radiation resistance and thermal properties over the traditional plastics (polyvinyltoluene and polystyrene). In this work, cross-linked polydimethyl-co-diphenylsiloxane (PMPS) scintillators with 22% molar percentage of diphenylsiloxane units have been synthesised. 2,5-Diphenyloxazole and Lumogen Violet (BASF) were employed as primary and secondary fluor, respectively. Thermal neutrons sensitivity was achieved through the addition of 3% wt of ortho-carborane. Scintillation yield measurements were made by exciting with (241)Am alpha source samples with different concentrations of dye molecules. PMPS-based scintillators with ?50% light yield as compared with the commercial plastic scintillator EJ212 were produced. The scintillation yield of the B-loaded samples under thermal neutrons was tested with a moderated Am-Be source and compared with the commercially available EJ254 (5% wt B). 2.2 MeV neutrons were produced by irradiating with a 4.0 MeV proton beam an LiF target, thus exploiting the reaction (7)Li(p,n)(7)Be. Time-of-flight measurements were performed to distinguish pulses due to neutrons or gamma. A similar test was performed with an EJ254 commercial scintillator for comparison. Using the same set-up, polyethylene bricks were used as a moderator to produce low-energy neutrons for testing B-loaded samples. PMID:21112884

Carturan, S; Quaranta, A; Marchi, T; Gramegna, F; Degerlier, M; Cinausero, M; Kravchuk, V L; Poggi, M

2010-11-25

458

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

459

11C Background in Liquid Scintillator Detectors  

SciTech Connect

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

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

2005-09-08

460

Fiber optic thermal/fast neutron and gamma ray scintillation detector  

DOEpatents

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

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

2007-10-30

461

Characteristics of quasi-periodic scintillations observed at low latitude  

NASA Astrophysics Data System (ADS)

Quasi-periodic scintillations are characterized as primary deep fadeout in field strength, associated with regular ringing patterns before and after it. In this paper, observations of quasi-periodic scintillations using geostationary satellite (FLEETSAT) transmissions operating at frequency 250 MHz at low-latitude ground station, Varanasi (geomagnetic latitude 14°55'N, longitude 153°59'E), are reported. The results indicate that the quasi-periodic scintillations are most likely produced by plasma blobs/bubbles present in the E and F regions of the ionosphere which are helpful in identifying the generation mechanism of the associated irregularities. The various characteristic features of the different types of quasi-periodic scintillations observed at low latitude are discussed for the first time in detail based on a highly comprehensive analysis of longer data sets using autocorrelation, power spectrum, and scintillation index analysis. The computed horizontal scale size of the quasi-periodic scintillations producing irregularity varies from 100 to 1300 m which shows that the irregularities are of intermediate-scale sizes. The spectral index obtained from the slopes of power spectrum varies from -2 to -8. All of these observed results are important for identifying the generation mechanism of ionospheric irregularities associated with quasi-periodic scintillations. The observed fading patterns, especially the modulation of the diffraction patterns (fading envelopes), can be explained by considering an obstacle called radio lens in the ionosphere elongated in one direction. For the first time, we have successfully simulated the amplitude versus time plots of almost all types of quasi-periodic scintillation patches and found that our modeled and observed characteristics of quasi-periodic scintillation patches compare well with each other.

Patel, Kalpana; Singh, Ashutosh K.; Singh, A. K.; Singh, R. P.

2009-12-01

462

Scintillation of liquid helium for low-energy nuclear recoils  

NASA Astrophysics Data System (ADS)

The scintillation properties of liquid helium upon the recoil of a low-energy helium atom are discussed in the context of the possible use of this medium as a detector of dark matter. It is found that the prompt scintillation yield in the range of recoil energies from a few keV to 100 keV is somewhat higher than that obtained by a linear extrapolation from the measured yield for a 5-MeV ? particle. A comparison is made of both the scintillation yield and the charge separation by an electric field for nuclear recoils and for electrons stopped in helium.

Ito, T. M.; Seidel, G. M.

2013-08-01

463

Deuterated plastic scintillator for proton detection in a neutron background  

NASA Astrophysics Data System (ADS)

Deuterated scintillators are proposed as detectors in neutron spectrometers based on the proton recoil method as a means to reduce the interference from background. Specifically, the use of a deuterated scintillator hodoscope in the focal plane of a magnetic proton recoil spectrometer is considered. The response of the hodoscope to signal protons and background neutrons is determined with Monte Carlo simulations and measurements with a 239Pu-Be source. The results are discussed relative to the use of regular hydrogen based scintillators with an assessment of the expected gain in a focal plane detector for fusion neutron applications.

Frenje, J.; Conroy, S.; Ericsson, G.; Källne, J.; Renberg, P.-U.; Traneus, E.

1996-02-01

464

Scintillating micro fibers with polymethylphenylsiloxane core and silica cladding  

NASA Astrophysics Data System (ADS)

We have developed a new method to produce bundles of scintillating micro fibers. It consists in filling a glass capillary with a viscous polymer which is chemically cross-linked to obtain a hard core. Using a polymethylphenylsiloxane (Toshiba XE 5844) doped with a single wavelength shifter, 1-p-anisyl-3-mesityl-2-pyrazolin (PMP 450) at a concentration of 0.006 mol l-1, we obtained an attenuation length of 70 cm. The scintillation efficiency is similar to a good quality commercial plastic scintillator.

Llop, X.; Farenc, J.; Destruel, P.; Teyssié, D.; Boileau, S.

1994-08-01

465

Light output of EJ228 scintillation neutron detectors.  

PubMed

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

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

2010-10-29

466

Calibration of Small Plastic Scintillators for Imaging Applications  

SciTech Connect

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

Pozzi, S.

2005-01-19

467

A 2-phase liquid scintillation assay for glycolipid synthetases  

SciTech Connect

Glycolipid synthetases can be assayed conveniently by incubating the lipid substrate with the radiosugar-labeled nucleotide in a small plastic scintillation vial. At the end of the incubation period, water and perchloric acid are added, then n-butanol, then a toluene-based scintillation cocktail. The radioactive lipid partitions into the scintillation fluid, leaving excess sugar nucleotide in the aqueous phase. Only a small fraction of the total radioactivity in the aqueous layer is detectable. This method is illustrated for ceramide:UDP-glucose glucosyltransferase. The approach should be applicable to other lipid synthetases that can be assayed with radioactive hydrophilic substrate.

Hospattankar, A.V.; Radin, N.S.

1981-10-01

468

Fast neutron detection with pressurized 4He scintillation detectors  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

469

Screening for EGFR mutations in lung cancer.  

PubMed

Certain mutations in the epidermal growth factor receptor (EGFR) gene confer hypersensitivity to the tyrosine kinase inhibitors gefitinib and erlotinib in patients with advanced non-small cell lung cancer. Large-scale screening for EGFR mutations in such patients is feasible for predicting response to TKIs and thus guiding treatment. PMID:20040267

Molina-Vila, Miguel A; Bertran-Alamillo, Jordi; Mayo, Clara; Rosell, Rafael

2009-12-01

470

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

471

Uranium scintillator calorimeter at the CERN ISR  

SciTech Connect

The design, Monte Carlo studies and test beam results of a uranium/scintillator calorimeter to be installed in the Intersecting Storage Ring (ISR) at CERN are described. In its final stage the calorimeter will cover the full azimuth over a polar region of 45/sup 0/ < theta < 135/sup 0/. The full calorimeter is built in a modular way from 128 stacks, with each stack internally subdivided into six cells of 20 x 20 cm/sup 2/ cross section. The readout is by wavelength shifting (WLS) plates with a separate readout of the front part of the calorimeter (first ten plates) to allow electromagnetic/hadronic separation. Since the