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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

Theory of thin screen scintillations for a spherical wave  

NASA Technical Reports Server (NTRS)

A thin screen scintillation theory for a spherical wave is presented under the 'quasi-optical' approximation. We calculate the 'scattering angle', the 'observed angle', the intensity correlation function and the temporal pulse broadening for the random wave. It is found that as the wave propagates outward away from the phase screen, the correlation scale of the intensity fluctuation increases linearly while the 'observed angle' decreases linearly. The calculations are carried out for both Gaussian and power-law spectra of the turbulent medium.

Lee, L. C.

1976-01-01

3

Optimization of screening for radioactivity in urine by liquid scintillation.  

SciTech Connect

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

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

2007-08-01

4

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

SciTech Connect

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

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

2010-10-15

5

Quenching Effect, Signal to Noise, Contrast to Noise Ratios on Scintillator Screens for Proton Beam Dosimetry System  

NASA Astrophysics Data System (ADS)

There has been dosimetry using scintillator screen for proton quality assurance recently. To develop a proton beam dosimetry system using scintillator, we evaluated the dosimetric properties and imaging quality for three kinds of scintillator screens. Proton beam ranges of 6, 9, and 12 g/cm2 were determined in a water phantom using an ion chamber. Beam current was optimized about each scintillator screen at proton beam ranges of 6, 9, and 12 g/cm2. Dose rate was in beam condition of proton treatment. For comparison of the dosimetric properties, the quenching correction factors and standard deviations for the scintillator screens (C6H6, Gd2O2S:Tb, and Gd2O2S) were obtained using the relation between the light yield (scintillator-relative output) and the dose distribution (diode-relative output). The image qualities for the scintillator screens were compared, using the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR), in consideration of the physical properties of the scintillator materials. After correction of the quenching effect, the correction factor for scintillator screen Gd2O2S:Tb was the lowest, at 0.004 g/(cm2 MeV). The standard deviations of the difference between the yields measured by the scintillator screens and the diode detector averaged 1, 1.3, and 1.3, respectively, at all of the ranges from origin to the peak position. The dosimetric properties of scintillator screens were no large difference. The SNRs of the scintillator screens (C6H6, Gd2O2S:Tb, and Gd2O2S) averaged 28.67, 40.18, and 24.56, respectively, at all ranges. The CNRs of the scintillator screens (C6H6, Gd2O2S:Tb, and Gd2O2S) averaged 0.44, 0.33, and 0.42, respectively, at all ranges. The highest SNR and the lowest CNR of scintillator screen Gd2O2S:Tb were more excellent than those of the other scintillator screens. We evaluated the dosimetric properties in terms of the quenching-effect correction factors, standard deviations image qualities in terms of SNR and CNR about scintillator screens. The correction factor and standard deviation for scintillator screens made no large difference. Scintillator screen Gd2O2S:Tb had the highest value of SNR and the lowest value of CNR, and accordingly was considered to be best in proton beam imaging quality.

Kim, Seonkyu; Byeong Lee, Se; Yoo, Seung Hoon; Cho, Sungkoo; Kim, Dong Wook; Shin, Dongho; Park, Sung Yong; Kim, Chan Hyeong; Lee, Sang Hoon

2012-04-01

6

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

7

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

PubMed

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

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

2010-10-01

8

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

9

FIELD SCREENING METHODS CATALOG: USER'S GUIDE  

EPA Science Inventory

The Field Screening Methods Catalog contains a compilation of methods that were identified as being used in EPA Regions. Several methods contain no method performance information, because this information was not available. The Catalog was developed to assist the user in identify...

10

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

E-print Network

Alcohol Screening and Brief Intervention for Youth: A Practitioner's Guide Produced by the National Institute on Alcohol Abuse and Alcoholism In collaboration with the American Academy of Pediatrics October Division of Adolescent Medicine Orton Jackson Endowed Chair in Adolescent Medicine The Children's Hospital

Bandettini, Peter A.

11

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

12

Inverted-conical light guide for crosstalk reduction in tightly-packed scintillator matrix and MAPMT assembly  

NASA Astrophysics Data System (ADS)

In this paper we present the Inverted-Conical light guide designed for optical crosstalk reduction in the scintillator-MAPMT assemblies. The research was motivated by the 30% crosstalk observed in UFFO X-ray telescope, UBAT, during the preliminary calibration with MAPMTs of 64 2.88 × 2.88 mm2 pixels and identically gridded YSO crystal matrices. We began the study with the energy and crosstalk calibrations of the detector, then we constructed a GEANT4 simulation with the customized metallic film model as the MAPMT photocathode. The simulation reproduced more than 70% of the crosstalk and explained it as a consequence of the total reflection produced by the photocathode. The result indicated that the crosstalk mechanism could be a common case in most of the contact-assembled scintillation detectors. The concept of the Inverted-Conical light guide was to suppress the total reflection by contracting the incident angle of the scintillation. We optimized the design in the simulation and fabricated a test sample. The test sample reduced 52% crosstalk with a loss of 6% signal yield. The idea of the Inverted-Conical light guide can be adapted by scintillation detectors multi-pixel, imaging-purpose scintillation detectors such as the ultra-fast GRB observatory UFFO-UBAT, whose performances are sensitive to responding time, image resolution, and geometrical modifications.

Chang, Y.-Y.; Chen, C. R.; Chen, P.; Huang, J.-J.; Huang, M. A.; Liu, T.-C.; Nam, J. W.; Wang, M.-Z.; Bogomolov, V.; Brandt, S.; Budtz-Jørgensen, C.; Castro-Tirado, A. J.; Choi, H. S.; Connell, P. H.; Eyles, C.; Jeong, S.; Kim, J. E.; Kim, M. B.; Kim, S.-W.; Lee, J.; Lim, H.; Min, K. W.; Panasyuk, M. I.; Park, I. H.; Petrov, V.; Reglero, V.; ?ípa, J.; Rodrigo, J. M.; Svertilov, S.; Yashin, I.

2015-01-01

13

Short Interfering RNA Guide Strand Modifiers from Computational Screening  

PubMed Central

Short interfering RNAs (siRNAs) are promising drug candidates for a wide range of targets including those previously considered “undruggable”. However, properties associated with the native RNA structure limit drug development and chemical modifications are necessary. Here we describe the structure-guided discovery of functional modifications for the guide strand 5’ end using computational screening with the high resolution structure of human Ago2, the key nuclease on the RNA interference pathway. Our results indicate the guide strand 5’-end nucleotide need not engage in Watson-Crick (W/C) H-bonding but must fit the general shape of the 5’-end binding site in MID/PIWI domains of hAgo2 for efficient knockdown. 1,2,3-Triazol-4-yl bases formed from the CuAAC reaction of azides and 1-ethynylribose, which is readily incorporated into RNA via the phosphoramidite, perform well at the guide strand 5’-end. In contrast, purine derivatives with modified Hoogsteen faces or N2 substituents are poor choices for 5’-end modifications. Finally, we identified a 1,2,3-triazol-4-yl base incapable of W/C H-bonding that performs well at guide strand position 12, where base pairing to target was expected to be important. This work expands the repertoire of functional nucleotide analogs for siRNAs. PMID:24152142

Onizuka, Kazumitsu; Harrison, Jason G.; Ball-Jones, Alexi A.; Ibarra-Soza, José M.; Zheng, Yuxuan; Ly, Diana; Lam, Walter; Mac, Stephanie; Tantillo, Dean J.; Beal, Peter A.

2013-01-01

14

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

PubMed

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

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

2010-06-21

15

New process for screen cutting: water-jet guided laser  

NASA Astrophysics Data System (ADS)

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

Perrottet, Delphine; Amorosi, Simone; Richerzhagen, Bernold

2005-07-01

16

Screening of alpha- and beta-emitting radionuclides using liquid scintillation counting and monitoring procedures in radiation emergencies.  

PubMed

Urine gross alpha and beta activity analysis was conducted, and an internal contamination screening method was adopted to monitor visitors to Japan after the Fukushima accident. In particular, spot urine samples were used to evaluate internal contamination for 16 mo, and a total of 90 people participated in gross alpha and beta emitter screening. An ultra-low-background liquid scintillation counter was used for measurement, and optimal pulse shape analysis values were determined by measuring alpha- and beta-emitting certified reference materials. Moreover, linearity and reproducibility were assessed to validate the adopted methods, and international intercomparison was conducted using synthetic urine samples by measuring alpha- and beta-emitting radionuclides in multi-contaminated samples. Here, the measurement results of visitors to Japan are discussed, and a screening procedure is established for gross alpha and beta activity analysis during radiation emergencies. PMID:25271927

Yoon, Seokwon; Ha, Wi-Ho; Yoo, Jaeryong; Lee, Seung-Sook

2014-11-01

17

Low noise scintillation detectors with a P-47 thin layer screen for electrons of several keV  

NASA Astrophysics Data System (ADS)

The applicability of a low-noise scintillation detector (ScD) for the registration of electrons of several keV energy has been studied employing photomultipliers (PM) of different types and sizes. With the application of a sedimented P-47 scintillation screen, the values of the low-energy sensitivity limit and those of the light conversion coefficient were determined as about 2.7-4.7 keV and 2.8-6.6 photoelectrons/keV, respectively, for the set of PM's (Philips-Valvo XP 2020, Philips-Valvo XP 2052, Philips-Valvo XP 2972, EMI 9124a) studied. It is concluded that such scintillation detectors might be used advantageously as electron counters in the range of E > 5 keV. Applications below this kinetic energy value are also feasible when applying a floating acceleration of several kV to the ScD — a voltage much lower than the values required for Everhart-Thornley detectors.

Kajcsos, Zs.; Meisel, W.; Griesbach, P.; Gütlich, P.; Sauer, Ch.; Kurz, R.; Hildebrand, K.; Albrecht, R.; Ligtenberg, M. A. C.

1994-09-01

18

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

PubMed Central

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°, 15°, 30°, and 45°) 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. PMID:19994503

Freed, Melanie; Miller, Stuart; Tang, Katherine; Badano, Aldo

2009-01-01

19

Hazard screening application guide. Safety Analysis Report Update Program  

SciTech Connect

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

none,

1992-06-01

20

Evaluation of powder/granular Gd2O2S:Pr scintillator screens in single photon counting mode under 140 keV excitation  

NASA Astrophysics Data System (ADS)

The aim of this paper is the evaluation of an alternative, low cost solution for the gamma detector in planar imaging. It is based on a powder scintillator, well established in X-ray imaging, and could be further exploited in simultaneous bimodal imaging systems. For this purpose, we have examined the performance of Gd2O2S:Pr powder scintillator, in the form of thick granular screens easily produced in the laboratory by commercially available Gd2O2S:Pr powder. The screen was coupled to a round position sensitive photomultiplier tube (R3292 PSPMT). The system's evaluation was performed in photon counting mode under 99mTc excitation. In all measurements, a general purpose hexagonal parallel collimator was used. Different samples of screens with coating thickness varying from 0.1 g/cm2 to 1.2 g/cm2 were tested. The 0.6 g/cm2 screen, corresponding to ~ 2 mm actual thickness, was found most efficient under 140 keV irradiation. The system`s performance with the proposed screen is reported with the modulation transfer function. Moreover sensitivity, spatial and energy resolution as well as the uniformity response using phantoms were measured. The performance of the proposed screen was compared with two CsI:Tl pixellated crystal arrays with 2 × 2 × 3 mm3 and 3 × 3 × 5 mm3pixel size. A spatial resolution, of 3 mm FWHM, for a 99mTc line source, was achieved at zero source to collimator distance. In addition, the Gd2O2S:Pr screen showed a slower degradation of the spatial resolution with increasing source to collimator distance e.g at 20 cm, the Gd2O2S:Pr screen showed aq spatial resolution of 8.4 mm while the spatial resolution of the pixellated crystals was 15 mm. Taking into account its easy production, its flexibility due to powder form, the very low cost and the good spatial resolution properties of the proposed alternative detector, powder scintillators could potentially be used for the construction of flexible detector geometries, such as ring type or gamma probes or as a low cost detector solution in educational photon counting imaging applications, complementary to standard X-ray imaging.

David, S.; Georgiou, M.; Loudos, G.; Michail, C.; Fountos, G.; Kandarakis, I.

2013-01-01

21

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

22

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

23

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

SciTech Connect

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

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

2013-06-15

24

Biomarker-guided screening of Juzen-taiho-to, an oriental herbal formulation for immunostimulation.  

PubMed

Juzen-taiho-to is an immunostimulatory herbal formulation that is clinically used in East Asia for cancer patients undergoing chemotherapy and radiation. The formulation stimulates various leukocytes, including T, B, and NK cells and macrophages. Although Juzen-taiho-to is known to contain numerous compounds with various pharmacological activities, it is not clear which compounds are responsible for the stimulation of individual cell types. Here, we conducted what we call "biomarker-guided screening" to purify compounds responsible for the macrophages stimulatory activity. To this end, gene expression was analyzed by a DNA array for macrophages treated with Juzen-taiho-to and DMSO (vehicle control), which identified intercellular adhesion molecule 1 as a biomarker of macrophage stimulation by Juzen-taiho-to. A quantitative reverse transcription polymerase chain reaction assay of intercellular adhesion molecule 1 was then used to guide the purification of active compounds. The screening resulted in the purification of a glycolipid mixture, containing ?-glucosylceramides. The glycolipid mixture potently stimulated intercellular adhesion molecule 1 expression in primary dendritic cells as well as in primary CD14+ (macrophages) cells. The identification of this glycolipid mixture opens up an opportunity for further studies to understand how plant-derived glycolipids stimulate macrophages and dendritic cells in a safe and effective manner as demonstrated by Juzen-taiho-to. PMID:24549928

Takaoka, Anna; Iacovidou, Maria; Hasson, Tal H; Montenegro, Diego; Li, Xiangming; Tsuji, Moriya; Kawamura, Akira

2014-03-01

25

A Guided Materials Screening Approach for Developing Quantitative Sol-gel Derived Protein Microarrays  

PubMed Central

Microarrays have found use in the development of high-throughput assays for new materials and discovery of small-molecule drug leads. Herein we describe a guided material screening approach to identify sol-gel based materials that are suitable for producing three-dimensional protein microarrays. The approach first identifies materials that can be printed as microarrays, narrows down the number of materials by identifying those that are compatible with a given enzyme assay, and then hones in on optimal materials based on retention of maximum enzyme activity. This approach is applied to develop microarrays suitable for two different enzyme assays, one using acetylcholinesterase and the other using a set of four key kinases involved in cancer. In each case, it was possible to produce microarrays that could be used for quantitative small-molecule screening assays and production of dose-dependent inhibitor response curves. Importantly, the ability to screen many materials produced information on the types of materials that best suited both microarray production and retention of enzyme activity. The materials data provide insight into basic material requirements necessary for tailoring optimal, high-density sol-gel derived microarrays. PMID:24022739

Helka, Blake-Joseph; Brennan, John D.

2013-01-01

26

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

27

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

28

T & I--Graphic Arts, Silk Screen Printing. Kit No. 60. Instructor's Manual [and] Student Learning Activity Guide.  

ERIC Educational Resources Information Center

An instructor's manual and student activity guide on silk screen printing are provided in this set of prevocational education materials which focuses on the vocational area of trade and industry (graphic arts). (This set of materials is one of ninety-two prevocational sets arranged around a cluster of seven vocational offerings: agriculture, home…

Cope, George

29

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.

30

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.

31

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

32

Scintillating Stars  

NSDL National Science Digital Library

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

Riddle, Bob

2003-02-01

33

snoSeeker: an advanced computational package for screening of guide and orphan snoRNA genes in the human genome  

Microsoft Academic Search

Small nucleolar RNAs (snoRNAs) represent an abundant group of non-coding RNAs in eukaryotes. They can be divided into guide and orphan snoRNAs according to the presence or absence of antisense sequence to rRNAs or snRNAs. Current snoRNA- searching programs, which are essentially based on sequence complementarity to rRNAs or snRNAs, exist only for the screening of guide snoRNAs. In this

Jian-Hua Yang; Xiao-Chen Zhang; Zhan-Peng Huang; Hui Zhou; Mian-Bo Huang; Shu Zhang; Yue-Qin Chen; Liang-Hu Qu

2006-01-01

34

Metabolomics guides rational development of a simplified cell culture medium for drug screening against Trypanosoma brucei.  

PubMed

In vitro culture methods underpin many experimental approaches to biology and drug discovery. The modification of established cell culture methods to make them more biologically relevant or to optimize growth is traditionally a laborious task. Emerging metabolomic technology enables the rapid evaluation of intra- and extracellular metabolites and can be applied to the rational development of cell culture media. In this study, untargeted semiquantitative and targeted quantitative metabolomic analyses of fresh and spent media revealed the major nutritional requirements for the growth of bloodstream form Trypanosoma brucei. The standard culture medium (HMI11) contained unnecessarily high concentrations of 32 nutrients that were subsequently removed to make the concentrations more closely resemble those normally found in blood. Our new medium, Creek's minimal medium (CMM), supports in vitro growth equivalent to that in HMI11 and causes no significant perturbation of metabolite levels for 94% of the detected metabolome (<3-fold change; ? = 0.05). Importantly, improved sensitivity was observed for drug activity studies in whole-cell phenotypic screenings and in the metabolomic mode of action assays. Four-hundred-fold 50% inhibitory concentration decreases were observed for pentamidine and methotrexate, suggesting inhibition of activity by nutrients present in HMI11. CMM is suitable for routine cell culture and offers important advantages for metabolomic studies and drug activity screening. PMID:23571546

Creek, Darren J; Nijagal, Brunda; Kim, Dong-Hyun; Rojas, Federico; Matthews, Keith R; Barrett, Michael P

2013-06-01

35

Ceramic-like scintillators  

Microsoft Academic Search

Scintillator bodies comprising fluorescent materials and having high optical translucency with low light absorption and methods of making the scintillator bodies are disclosed. In accordance with one embodiment of the invention, the scintillator bodies are formed by a hot-pressing process. In another embodiment, coldpressing followed by sintering is employed. Another embodiment employs controlled cooling. Another embodiment employs hotforging. The scintillator

D. A. Cusano; F. F. Holub; S. Prochazka

1980-01-01

36

FEDS user`s guide: Facility energy screening. Release 2.10  

SciTech Connect

The Facility Energy Decision Screening (FEDS) Model is under development at Pacific Northwest Laboratory (PNL) for the US DOE Federal Energy Management Program (DOE-FEMP) and the US Army Construction Engineering REsearch Laboratory (USA-CERL). FEDS is a multi-level energy analysis software system designed to provide a comprehensive approach to fuel-neutral, technology-independent, integrated (energy) resource planning and acquisition. The FEDS system includes Level-1, which is a top-down, first-pass energy systems analysis and energy resource acquisition decision software model for buildings and facilities, and the Level-2 software model, which allows specific engineering inputs and provides detailed output. The basic intent of the model is to provide an installation with the information necessary to determine the minimum life-cycle cost (LCC) configuration of the installation`s energy generation and consumption infrastructure. The model has no fuel or technology bias; it simply selects the technologies that will provide an equivalent or superior level of service (e.g., heating, cooling, illumination) at the minimum LCC.

Dirks, J.A.

1995-01-01

37

Expression of Translationally Controlled Tumor Protein (TCTP) Gene of Dirofilaria immitis Guided by Transcriptomic Screening  

PubMed Central

Dirofilaria immitis (heartworm) infections affect domestic dogs, cats, and various wild mammals with increasing incidence in temperate and tropical areas. More sensitive antibody detection methodologies are required to diagnose asymptomatic dirofilariasis with low worm burdens. Applying current transcriptomic technologies would be useful to discover potential diagnostic markers for D. immitis infection. A filarial homologue of the mammalian translationally controlled tumor protein (TCTP) was initially identified by screening the assembled transcriptome of D. immitis (DiTCTP). A BLAST analysis suggested that the DiTCTP gene shared the highest similarity with TCTP from Loa loa at protein level (97%). A histidine-tagged recombinant DiTCTP protein (rDiTCTP) of 40 kDa expressed in Escherichia coli BL21 (DE3) showed immunoreactivity with serum from a dog experimentally infected with heartworms. Localization studies illustrated the ubiquitous presence of rDiTCTP protein in the lateral hypodermal chords, dorsal hypodermal chord, muscle, intestine, and uterus in female adult worms. Further studies on D. immitis-derived TCTP are warranted to assess whether this filarial protein could be used for a diagnostic purpose. PMID:24623877

Fu, Yan; Lan, Jingchao; Wu, Xuhang; Yang, Deying; Zhang, Zhihe; Nie, Huaming; Hou, Rong; Zhang, Runhui; Zheng, Wanpeng; Xie, Yue; Yan, Ning; Yang, Zhi; Wang, Chengdong; Luo, Li; Liu, Li; Gu, Xiaobin; Wang, Shuxian; Peng, Xuerong

2014-01-01

38

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

PubMed Central

Background The global burden of bacterial infections is high and has been further aggravated by increasing resistance to antibiotics. In the search for novel antibacterials, three medicinal plants: Peperomia vulcanica, Peperomia fernandopoioana (Piperaceae) and Scleria striatinux (Cyperaceae), were investigated for antibacterial activity and toxicity. Methods Crude extracts of these plants were tested by the disc diffusion method against six bacterial test organisms followed by bio-assay guided fractionation, isolation and testing of pure compounds. The minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations were measured by the microdilution method. The acute toxicity of the active extracts and cytotoxicity of the active compound were performed in mice and mammalian cells, respectively. Results The diameter of the zones of inhibition (DZI) of the extracts ranged from 7–13?mm on Escherichia coli and Staphylococcus aureus of which the methylene chloride:methanol [1:1] extract of Scleria striatinux recorded the highest activity (DZI?=?13?mm). Twenty-nine pure compounds were screened and one, Okundoperoxide, isolated from S. striatinux, recorded a DZI ranging from 10–19?mm on S. aureus. The MICs and MBCs indicated that the Peperomias had broad-spectrum bacteriostatic activity. Toxicity tests showed that Okundoperoxide may have a low risk of toxicity with an LC50 of 46.88??g/mL. Conclusions The antibacterial activity of these plants supports their use in traditional medicine. The pure compound, Okundoperoxide, may yield new antibacterial lead compounds following medicinal chemistry exploration. PMID:22549052

2012-01-01

39

Relaxation and guided imagery used with 12-year-olds during venipuncture in a school-based screening study.  

PubMed

Needle-related procedures are reported to be problematic for children. In a school-based celiac disease screening, 12-year-olds' experiences with relaxation and guided imagery (R-GI) during venipuncture were investigated. One group tried nurse-led R-GI (n = 60) and another group received standard care (SC; n = 49). A mixed method design was applied using short written narratives, facial affective scale (FAS), and visual analog scale (VAS) for pain intensity. Qualitative content analysis highlighted that diversity and contradictions when facing blood tests. FAS scores were significantly lower in the SC group before (p = 0.01), during (p = 0.01), and after (p = 0.01) venipuncture. VAS scores did not differ between the groups. The blood test was mostly experienced as unproblematic, and GI during venipuncture did not decrease pain or affect. However, the fact that a number of children scored high FAS indicates a need for effective methods to help children cope with needle-related school-based procedures. PMID:23818144

Forsner, Maria; Norström, Fredrik; Nordyke, Katrina; Ivarsson, Anneli; Lindh, Viveca

2014-09-01

40

WGA-coated yttrium oxide beads enable an imaging-based adenosine 2a receptor binding scintillation proximity assay suitable for high throughput screening.  

PubMed

Adenosine receptors belong to the superfamily of G protein-coupled receptors and are involved in a variety of physiologic functions. Traditionally, binding assays to detect adenosine 2a (A2a) antagonists and agonists have used filtration methods that are cumbersome to run and not amenable to HTS. We developed scintillation proximity assays (SPA trade mark ) utilizing HEK293 RBHA2AM cell membranes, either wheat germ agglutinin (WGA)-coated yttrium silicate (YSi) or red-shifted yttrium oxide (YO) beads and the A2a-selective radioligand [(3)H]SCH 58261. Both beads gave windows (total binding/nonspecific binding) of >5 and K(d) values of 2-3 nM for the radioligand, in agreement with results obtained by filtration. In contrast, WGA-polyvinyltoluene as well as other bead types had windows of <3 and significant radioligand binding to the uncoated beads. A 384-well WGA-YO bead SPA was optimized utilizing a LEADseeker imaging system and an automated trituration process for dispensing the dense yttrium-based beads. Signals were stable after 4 h, and Z' values were 0.7-0.8. The LEADseeker imaging assay tolerated 2% dimethyl sulfoxide and generated IC(50) values of 3-5 nM for the A2a antagonist CGS 15943, comparable to that obtained by the filtration method. A number of adenosine and xanthine analogues were identified as hits in the Library of Pharmacologically Active Compounds (LOPAC). This imaging-based A2a SPA enables HTS and is a major improvement over the filtration method. PMID:15285910

Bryant, Robert; McGuinness, Debra; Turek-Etienne, Tammy; Guyer, Deborah; Yu, Liming; Howells, Leighton; Caravano, Joseph; Zhai, Ying; Lachowicz, Jean

2004-06-01

41

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

USGS Publications Warehouse

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 related to the availability of water resources to meet current and future water-use demands. The tool compares water-use information to an initial screening criteria of the 7-day, 10-year low-flow statistic (7Q10) resulting in a screening indicator for influences of net withdrawals (withdrawals minus discharges) on aquatic-resource uses. This report is intended to serve as a guide for using the screening tool. The WAST can display general basin characteristics, water-use information, and screening-indicator information for over 10,000 watersheds in the state. The tool includes 12 primary functions that allow the user to display watershed information, edit water-use and water-supply information, observe effects downstream from edited water-use information, reset edited values to baseline, load new water-use information, save and retrieve scenarios, and save output as a Microsoft Excel spreadsheet.

Stuckey, Marla H.; Kiesler, James L.

2008-01-01

42

Development of the Risk Appraisal Measure (RAM): A Brief Screen to Identify Risk Areas and Guide Interventions for Dementia Caregivers  

PubMed Central

Objectives Family caregivers play a significant role in the health care of patients with dementia yet their needs and health status are often overlooked. This study developed and validated a brief screening measure for use in research, health care and community settings to systematically assess well-being and identify needed areas of support for caregivers of patients with dementia. Design This study used data from Resources for Enhancing Alzheimer’s Caregiver Health (REACH II), a multi-site, randomized, clinical trial of a behavioral intervention designed to improve the quality of life of caregivers in multiple domains. PARTICIPANTS: Two-hundred and twelve Hispanic, 211 Black/African American and 219 White family community dwelling dementia caregiver dyads providing in-home care to patients with dementia. Measurement Based on conceptual and psychometric analyses, a 16-item measure was developed that taps six domains linked to caregiver risk and amenable to intervention: depression, burden, self-care and health behaviors, social support, safety, and patient problem behaviors. The reliability and validity of the instrument was evaluated with 642 dementia caregiver dyads from the REACH II program. Results The measure was found to have acceptable internal consistency for a multi-dimensional scale and similar measurement properties for each of the racial/ethnic groups. Concurrent validity was also demonstrated for the measure. Conclusion The REACH Risk Appraisal Measure (RAM) developed in this study shows promise as an assessment tool that can be used in research, clinical and community settings to guide, prioritize, and target needed areas of support for caregivers of patients with dementia. PMID:19453305

Czaja, Sara J.; Gitlin, Laura N.; Schulz, Richard; Zhang, Song; Burgio, Louis D.; Stevens, Alan B.; Nichols, Linda O.; Gallagher-Thompson, Dolores

2009-01-01

43

Scintillators and applications thereof  

DOEpatents

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

Williams, Richard T.

2014-07-15

44

Scintillator materials for calorimetry  

SciTech Connect

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

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

1994-09-01

45

Scintillator reflective layer coextrusion  

DOEpatents

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

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

2001-01-01

46

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. PMID:23700445

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

47

Recent development in organic scintillators  

NASA Technical Reports Server (NTRS)

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

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

1969-01-01

48

Shifting scintillator neutron detector  

DOEpatents

Provided are sensors and methods for detecting thermal neutrons. Provided is an apparatus having a scintillator for absorbing a neutron, the scintillator having a back side for discharging a scintillation light of a first wavelength in response to the absorbed neutron, an array of wavelength-shifting fibers proximate to the back side of the scintillator for shifting the scintillation light of the first wavelength to light of a second wavelength, the wavelength-shifting fibers being disposed in a two-dimensional pattern and defining a plurality of scattering plane pixels where the wavelength-shifting fibers overlap, a plurality of photomultiplier tubes, in coded optical communication with the wavelength-shifting fibers, for converting the light of the second wavelength to an electronic signal, and a processor for processing the electronic signal to identify one of the plurality of scattering plane pixels as indicative of a position within the scintillator where the neutron was absorbed.

Clonts, Lloyd G; Cooper, Ronald G; Crow, Jr., Morris Lowell; Hannah, Bruce W; Hodges, Jason P; Richards, John D; Riedel, Richard A

2014-03-04

49

Lead carbonate scintillator materials  

DOEpatents

Improved radiation detectors containing lead carbonate or basic lead carbonate as the scintillator element are disclosed. Both of these scintillators have been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to other known scintillator materials. The radiation detectors disclosed are favorably suited for use in general purpose detection and in medical uses. 3 figures.

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

1991-05-14

50

Augmenting on-screen instructions with micro-projected guides: when it works, and when it fails  

Microsoft Academic Search

We present a study that evaluates the effectiveness of augmenting on-screen instructions with micro-projection for manual task guidance unlike prior work, which replaced screen instructions with alternative modalities (e.g., head-mounted displays). In our study, 30 participants completed 10 trials each of 11 manual tasks chosen to represent a set of common task-components (e.g., cutting, folding) found in many everyday activities

Stephanie Rosenthal; Shaun K. Kane; Jacob O. Wobbrock; Daniel Avrahami

2010-01-01

51

Ionizations scintillation detectors  

NASA Astrophysics Data System (ADS)

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

Policarpo, A. J. P. L.

52

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

PubMed Central

Divers are taught some basic physiology during their training. There is therefore some underlying knowledge and understandable concern in the diving community about the presence of a patent foramen ovale (PFO) as a cause of decompression illness (DCI). There is an agreement that PFO screening should not be done routinely on all divers; however, when to screen selected divers is not clear. We present the basic physiology and current existing guidelines for doctors, advice on the management and identify which groups of divers should be referred for consideration of PFO screening. Venous bubbles after diving and right to left shunts are common, but DCI is rare. Why this is the case is not clear, but the divers look to doctors for guidance on PFO screening and closure; both of which are not without risks. Ideally, we should advise and apply guidelines that are consistent and based on best available evidence. We hope this guideline and flow chart helps address these issues with regard to PFOs and diving. PMID:23849539

2013-01-01

53

Scintillating plate calorimeter mechanical design  

Microsoft Academic Search

Progress on designs for compensating scintillator plate calorimeters will be presented. One design includes a lead composite absorber, fiber readout, and radiation hardened scintillator plates, and the second design has depleted uranium absorbers, wave length shifter plate readout, and scintillator plates. The lead absorber is cast with slots to accept the scintillator in the first design, while the depleted uranium

A. Buehring; N. Hill; T. Kirk; J. Nasiatka; E. Petereit; L. Price; J. Proudfoot; H. Spinka; D. Underwood; M. Burke; D. Hackworth; T. Hordubay; D. Marshik; D. Scherbarth; R. Swensrud

1990-01-01

54

Gravitational Interstellar Scintillation  

E-print Network

Gravitation could modulate the interstellar scintillation of pulsars in a way that is analogous to refractive interstellar scintillation (RISS). While RISS occurs when a large ionized cloud crosses the pulsar line-of-sight, gravitational interstellar scintillation (GISS) occurs when a compact gravitational deflector lies very near to that line-of-sight. However, GISS differs from RISS in at least two important respects: It has a very distinctive and highly predictible time signature, and it is non-dispersive. We find two very different astronomical contexts where GISS could cause observable diffraction-pattern distortions: Highly inclined binary pulsars, and the kind of compact interstellar clouds suspected of causing extreme scattering events.

Redouane Al Fakir

2008-05-23

55

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

SciTech Connect

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

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

2012-03-15

56

A mid-latitude scintillation model  

NASA Astrophysics Data System (ADS)

Radiowave scintillation in the presence of ionospheric disturbances has the potential to disrupt numerous transionospheric radio and radar systems. This report describes development of a model characterizing the plasma density irregularities that produce scintillation in the naturally disturbed mid latitude F layer. The model will be incorporated into Program WBMOD, which includes subroutines for computing both link geometry and scintillation indices, the latter by means of phase screen diffraction theory. Earlier versions of WBMOD, were based on extensive analysis of scintillation data collected in the auroral and equatorial zones in Wideband Satellite Mission. The model described herein is based on similarly extensive analysis of Wideband data from one mid latitude station and of data collected from HiLat satellite at another mid latitude station. The model describes irregularities at an effective height of 350 km that are isotropic across the geomagnetic field and elongated by a factor of 10 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 apex latitude of the point. The report highlights a disagreement by a factor of approximately three between irregularity strength inferred from the two satellites in a region of overlap between the two mid-latitude stations.

Robins, Robert E.; Secan, James A.; Fremouw, E. J.

1986-10-01

57

Usefulness of Succinate dehydrogenase B (SDHB) immunohistochemistry in guiding mutational screening among patients with pheochromocytoma-paraganglioma syndromes.  

PubMed

Genetic testing of pheochromocytomas (PCC) and paragangliomas (PGL), although expensive, is gradually becoming a part of the routine laboratory investigation for patients with PCC-PGL syndrome. Recently, Succinate dehydrogenase B (SDHB) immunochemistry has been shown to be an excellent indicator of germline mutations in the SDH genes and could help significantly reduce cost. This study assesses the utility of SDHB immunohistochemical analysis when used to guide genetic analysis, with emphasis on cost benefits it could provide in a resource-limited setting. Forty-four cases of PCC/PGL characterized by genetic analysis were included to determine their SDHB expression pattern by immunohistochemistry. SDHB antibody expression was negative among three cases each, with SDHB and SDHD mutations. Immunohistochemistry results were positive for all three cases of RET, a single case of neurofibromatosis and for two cases with Von Hippel-Lindau (VHL) mutations while the remaining two cases with VHL mutations showed a diffuse 'cytoplasmic blush'. Thirty of the remaining 31 samples demonstrated positive staining and were negative for mutations, while a lone sample that was negative for staining and mutation was not included in the final analysis as the internal control for the sample was not adequately stained. Cost analysis in our settings showed that triaging with SDHB immunohistochemistry could potentially reduce costs by USD 320-500 per patient. SDHB immunohistochemistry, when used as a guide to genetic testing, can significantly reduce the effort, time and costs of testing among patients with PCC-PGL, a huge benefit in resource limited settings. PMID:24735130

Pai, Rekha; Manipadam, Marie Therese; Singh, Pradyumn; Ebenazer, Andrew; Samuel, Prasanna; Rajaratnam, Simon

2014-11-01

58

Equatorial scintillations - A review  

NASA Technical Reports Server (NTRS)

Scintillation observations of equatorial irregularities by techniques such as in situ, radar backscatter, airglow, and total electron content are reviewed, with an emphasis on GHz measurements. New aspects of the spread-F analysis from ionograms are mentioned, followed by a discussion of scintillation morphology, and the longitudinal control of the equatorial scintillations is emphasized. A coordinated multitechnique observation of the equatorial irregularities is described in detail, the study being divided into two parts: (1) an examination of the large field-aligned irregularity structures and their association with discrete patches of scintillation activity, and (2) an investigation of the coexistence of km-scale-irregularities with meter scales and a description of the evolution of the irregularity and scintillation spectra during the various phases of irregularity generation and decay. Unsolved problems are also reviewed, e.g., it is stated that the effects of steep spatial gradients in the electron density structures and their subsequent erosion on both CW and pulse propagation need to be evaluated both from the point of view of theory and experiments.

Basu, S.; Basu, S.

1981-01-01

59

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

60

Laser beam scintillation beyond the turbulent atmosphere A numerical computation  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

61

Scintillator Strip ECAL Optimization  

E-print Network

The CALICE collaboration is developing a granular electromagnetic calorimeter using small scintillator strips for a future linear collider experiment. On developing of ~ 10^7 channel-ECAL in particle flow approach, CALICE is developing a technological prototype with 144 of 5 x 45 x (1 - 2) mm^3 strips on each 180 x 180 mm^2 base board unit in tandem with developing the design of scintillator strip and pixelated photon detector and their coupling after established the physics prototype which has required performance. A method of event reconstruction in such ECAL is also developed.

Katsushige Kotera

2014-04-07

62

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

63

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

64

Scanning type scintillation camera  

SciTech Connect

The effective area of observation of a scanning-type scintillation camera is expanded relative to the actual area scanned by shifting the position of a spatial window back and forth in the direction of scanning so that the sum of the window velocity and the velocity of actual scanning represents a predetermined scanning velocity.

Nagasawa, Y.

1981-06-16

65

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

66

Scintillation Light from Cosmic-Ray Muons in Liquid Argon  

E-print Network

This paper reports the results of the first experiment to directly measure the properties of the scintillation light generated by minimum ionizing cosmic-ray muons in liquid argon. Scintillation light from these muons is of value to studies of weakly-interacting particles in neutrino experiments and dark matter searches, as well as for particle identification. The experiment was carried out at the TallBo facility at Fermilab using prototype light guides and electronics developed for the Long-Baseline Neutrino Experiment. Analysis of the time-resolved structure of the scintillation light from cosmic-ray muons gives $\\langle \\tau_{\\text{T}}\\rangle = 1.43 \\pm 0.04~\\text{(stat.)} \\pm 0.007~\\text{(sys.)}~\\mu$s for the triplet light decay time constant. The ratio of singlet to triplet light measured using surface-coated light guides is $R = 0.39 \\pm 0.01~\\text{(stat.)} \\pm 0.008~\\text{(sys.)}$. There is some evidence that this value is not consistent with $R$ for minimum ionizing electrons. However, the value for $R$ measured here clearly differs significantly from $R$ found for heavily ionizing particles like alphas. Furthermore, there is no apparent difference in $R$ measured using light guides coated with TPB versus bis-MSB, adding additional evidence that bis-MSB is a promising alternative to TPB for detecting scintillation light in liquid argon.

Denver Whittington; Stuart Mufson

2014-08-08

67

Scintillation detectors based on silicon microfluidic channels  

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

68

Thrombophilia Screening.  

PubMed

Although controversial, screening for thrombophilia has become common. Testing for antiphospholipid antibodies is indicated in order to guide treatment decisions if there is clinical suspicion for antiphospholipid syndrome. The utility of identifying other thrombophilias in symptomatic venous thromboembolism (VTE) is questionable, as the risk of recurrence does not appear to be increased by an appreciable degree with the most common disorders (heterozygosity for factor V Leiden or prothrombin mutation). Although recurrence appears to be increased in those with homozygous or multiple abnormalities and potentially deficiencies in natural anticoagulants, screening to detect these conditions is difficult to justify based on their rarity. The American College of Chest Physicians' current guidelines note the increased risk of recurrence with idiopathic, proximal events regardless of thrombophilia status. They suggest duration of anticoagulation therapy be based on location and provoking factors rather than whether or not the individual has a thrombophilia. Because routine prophylaxis in asymptomatic individuals with thrombophilia is not recommended, screening of asymptomatic family members is difficult to justify. Screening prior to prescribing combination oral contraceptives is not cost effective, may result in unwanted pregnancies, and may have little effect on the overall rate of VTE. PMID:24739279

Hornsby, Lori B; Armstrong, Emily M; Bellone, Jessica M; Treadway, Sarah; Phillippe, Haley M

2014-04-16

69

The Next Generation Scintillator-based Electromagnetic Calorimeter Prototype and Beam Test  

NASA Astrophysics Data System (ADS)

We are studying next generation scintillation detectors for future collider experiments. For precise energy measurement of energetic jets in future experiments, particle flow algorithm with fine granular scintillator strip calorimeter will play an important role. To establish the technology of the calorimeter, we are studying the properties of small plastic scintillator strips with size of (10-5) x 50 x 3 mm, which is a fundamental component of the calorimeter. As a part of this R&D study, small extruded plastic Scintillator of size 10 x 45 x 3 mm and a tungsten plate with 3.5 mm thick are sampled together to Fabricate a Scintillator base electromagnetic calorimeter prototype. Prototype has a stack of 30 layers, having dimension of 20 x 20 cm. Fine Scintillator strips in successive layers aligned in orthogonal to achieve effective 1 x 1 cm segmentation. The total number of channels is 2160 for readout. scintillation light produced in plastic Scintillator strips enters the wavelength shifting (WLS) fiber placed inside the plastic Scintillator are guided to the sensitive photo detector 1600 pixel MPPC (Multi Pixel Photon Counter) with a sensitive region of 1 x 1 mm2. The electromagnetic calorimeter performance has been studied with test beam during summer 2008 and 2009 at Fermilab. We have injected 1-30 GeV electron and 60 GeV Pion beams and measured energy resolution and linearity of response toward input energy. In this presentation we will present obtained performance of the calorimeter prototype.

Khan, Adil; The Calice Collaboration

70

Scintillation proximity assay of arginine methylation.  

PubMed

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

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

2012-02-01

71

Deformation welding on scintillating materials  

SciTech Connect

Experiments on connecting scintillating crystals to form homogeneous pieces by means of plastical deformation are described. Optical transmission, radiation hardness, and scintillation spectra have been used for the evaluation of the quality of the bond. The results of experiments on fluorides of cerium, barium, and lead; and cesium iodide confirm that deformation welding can be used successfully for economic manufacturing of large homogeneous scintillators from several smaller parts.

Bazhenov, A.V.; Egorov, V.K.; Gasparov, L.V.; Klassen, N.V.; Mahonin, S.I.; Shmurak, S.Z.; Shmyt`ko, I.M. [Russian Academy of Sciences, Chernogolovka (Russian Federation). Inst. of Solid State Physics

1994-12-31

72

Comparative Accuracy of Anal and Cervical Cytology in Screening for Moderate to Severe Dysplasia by Magnification Guided Punch Biopsy: A Meta-Analysis  

PubMed Central

Background The accuracy of screening for anal cancer precursors relative to screening for cervical cancer precursors has not been systematically examined. The aim of the current meta-analysis was to compare the relative accuracy of anal cytology to cervical cytology in discriminating between histopathologic high grade and lesser grades of dysplasia when the reference standard biopsy is obtained using colposcope magnification. Methods and Findings The outcome metric of discrimination was the receiver operating characteristic (ROC) curve area. Random effects meta-analysis of eligible studies was performed with examination of sources of heterogeneity that included QUADAS criteria and selected covariates, in meta-regression models. Thirty three cervical and eleven anal screening studies were found to be eligible. The primary meta-analytic comparison suggested that anal cytologic screening is somewhat less discriminating than cervical cytologic screening (ROC area [95% confidence interval (C.I.)]: 0.834 [0.809–0.859] vs. 0.700 [0.664–0.735] for cervical and anal screening, respectively). This finding was robust when examined in meta-regression models of covariates differentially distributed by screening setting (anal, cervical). Conclusions Anal cytologic screening is somewhat less discriminating than cervical cytologic screening. Heterogeneity of estimates within each screening setting suggests that other factors influence estimates of screening accuracy. Among these are sampling and interpretation errors involving both cytology and biopsy as well as operator skill and experience. PMID:21949801

Mathews, Wm. Christopher; Agmas, Wollelaw; Cachay, Edward

2011-01-01

73

Rare earth phosphors and phosphor screens  

DOEpatents

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

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

1981-01-01

74

Lithium-loaded liquid scintillators  

SciTech Connect

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

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

2012-05-15

75

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 cm 3).

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

1987-08-01

76

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

77

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

78

Free liquid scintillation counting bibliography  

SciTech Connect

Packard Instrument Company announces the availability of its newly updated Bibliography of Packard Tri-Carb Liquid Scintillation Analyzers. This unique new booklet lists 628 references in which Packard Tri-Carb{reg_sign} liquid scintillation analyzers have been used in life science, environmental, nuclear power and archaeological measurements. All listings are cross-referenced by radionuclide, specific field of study and author.

NONE

1996-12-31

79

Proceedings of the 1st International Workshop "Radiopure Scintillators for EURECA" (RPScint'2008)  

E-print Network

Workshop RPSCINT'2008 was organized in Kyiv (Ukraine) on 9th and 10th September 2008. The idea was to bring together physicists, chemists, crystal scintillator experts and manufacturers to discuss the requirements of low-count rate experiments, in particular the required radiopurity and scintillation properties; selection and screening of input materials; purification of materials; raw compound preparation; crystal growing, annealing and handling; test of crystals; search for and development of new scintillating materials. Some contributions to the RPSCINT 2008 workshop are presented in these proceedings.

E. Armengau; M. Bauer; I. Bavykina; A. Benoit; A. Bento; J. Blumer; L. Bornschein; A. Broniatowski; G. Burghart; P. Camus; A. Chantelauze; M. Chapellier; G. Chardin; C. Ciemniak; C. Coppi; N. Coron; O. Crauste; F. A. Danevich; E. Daw; X. Defay; M. De Jesus; P. de Marcillac; G. Deuter; J. Domange; P. Di Stefano; G. Drexlin; A. M. Dubovik; L. Dumoulin; K. Eitel; F. von Feilitzsch; D. Filosofov; P. Gandit; E. Garcia; J. Gascon; G. Gerbier; J. Gironnet; V. G. Glebovsky; H. Godfrin; D. Grigoriev; B. V. Grinyov; S. Grohmann; M. Gros; M. Hannewald; D. Hauff; F. Haug; S. Henry; P. Huff; J. Imber; S. Ingleby; C. Isaila; J. Jochum; A. Juillard; M. Kiefer; M. Kimmerle; H. Kluck; V. V. Kobychev; G. P. Kovtun; V. Kozlov; H. Kraus

2009-03-09

80

Complications of transrectal ultrasound-guided systematic sextant biopsies of the prostate: evaluation of complication rates and risk factors within a population-based screening program  

Microsoft Academic Search

Objectives. Screening for prostate cancer to reduce the mortality and morbidity from this disease has become an important issue in recent years. Of all procedures used to diagnose prostate cancer, biopsy of the prostate is the cause of most complications. To evaluate the safety of the screening procedure, we have studied the complications and risk factors for complications within the

John B. W. Rietbergen; Arto E. Boeken Kruger; Ries Kranse; Fritz H. Schröder

1997-01-01

81

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

82

Scintillator materials containing lanthanum fluorides  

DOEpatents

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

Moses, W.W.

1991-05-14

83

Newborn Hearing Screening: Present Scenario  

PubMed Central

In 2009 many countries of the world met to discuss newborn and infant hearing screening current issues and guiding principles for action under World Health Organization (WHO) banner, though most of the countries who had begun this work as universal program or high risk screen do not have exact data and protocol. The developing countries also decided to become part of it and common guideline was proposed. India being part of it included hearing screening as one of the 30 diseases to be screened under Rashtriya Bal Swasthya Karyakram (RBSK). This article discusses all these issues of newborn hearing screening in the world and India. PMID:25657515

Singh, Vishwambhar

2015-01-01

84

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

85

Response of liquid scintillator assemblies as a function of angular orientation  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

86

Scintillation Light from Cosmic-Ray Muons in Liquid Argon  

E-print Network

This paper reports the results of the first experiment to directly measure the properties of the scintillation light generated by minimum ionizing cosmic-ray muons in liquid argon. Scintillation light from these muons is of value to studies of weakly-interacting particles in neutrino experiments and dark matter searches, as well as for particle identification. The experiment was carried out at the TallBo facility at Fermilab using prototype light guides and electronics developed for the Long-Baseline Neutrino Experiment. Analysis of the time-resolved structure of the scintillation light from cosmic-ray muons gives $\\langle \\tau_{\\text{T}}\\rangle = 1.43 \\pm 0.04~\\text{(stat.)} \\pm 0.007~\\text{(sys.)}~\\mu$s for the triplet light decay time constant. The ratio of singlet to triplet light measured using surface-coated light guides is $R = 0.39 \\pm 0.01~\\text{(stat.)} \\pm 0.008~\\text{(sys.)}$. There is some evidence that this value is not consistent with $R$ for minimum ionizing electrons. However, the value for $...

Whittington, Denver

2014-01-01

87

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

PubMed Central

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

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

2011-01-01

88

Statistics of the scintillation output using a combined x-ray/electron/optical Monte Carlo method  

NASA Astrophysics Data System (ADS)

Simulations of digital imaging systems based on scintillator screens usually employ a Poisson model for the phosphor conversion gain. However, the statistics of the scintillation output are determined by complex phenomena that involve many sources of variability including inhomogeneities in the crystalline and screen structure, variations in the deposited energy for each primary quantum available for excitation, variations in the relationship between radiate and non-radiative decay processes, energy dependencies in the conversion gain variance, and spread of secondary quanta. We use a combined x-ray/electron/optical Monte Carlo code to study the statistics of the scintillation output in columnar phosphors. The simulation code is the result of merging the x-ray transport code PENELOPE and the optical transport code DETECT-II. Using an improved geometric model for the columnar structure, we present results concerning pulse-height spectra of the scintillation output (and corresponding Swank factors) as a function of x-ray energy. This study improves our understanding of the underlying causes of conversion gain variations and should facilitate more accurate simulation efforts for the investigation and optimization of image acquisition systems based on scintillator screens.

Badano, Aldo; Sempau, Josep; Jennings, Robert J.

2005-04-01

89

FNAL-NICADD extruded scintillator  

SciTech Connect

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

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

2005-09-01

90

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

91

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

NASA Technical Reports Server (NTRS)

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

Narayan, Ramesh; Hubbard, W. B.

1988-01-01

92

Development of radiation hard scintillators  

SciTech Connect

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 atmosphere. One of the formulations tested showed an immediate decrease in pulse height of only 4% and has remained stable for 12 days while annealing in air. By comparison a commercial PVT scintillator showed an immediate decrease of 58% and after 43 days of annealing in air it improved to a 14% loss. The formulated sample consisted of 70 parts by weight of Dow polystyrene, 30 pbw of pentaphenyltrimethyltrisiloxane (Dow Corning DC 705 oil), 2 pbw of p-terphenyl, 0.2 pbw of tetraphenylbutadiene, and 0.5 pbw of UVASIL299LM from Ferro.

Markley, F.; Woods, D.; Pla-Dalmau, A.; Foster, G. (Fermi National Accelerator Lab., Batavia, IL (United States)); Blackburn, R. (Michigan Univ., Nuclear Reactor Lab., Ann Arbor, MI (United States))

1992-05-01

93

Studies on scintillating fiber response  

NASA Astrophysics Data System (ADS)

Scintillating fibers of type Bicron BCF-12 with 2 × 2 mm 2 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

94

Development of radiation hard scintillators  

NASA Astrophysics Data System (ADS)

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 atmosphere. One of the formulations tested showed an immediate decrease in pulse height of only 4% and has remained stable for 12 days while annealing in air. By comparison a commercial PVT scintillator showed an immediate decrease of 58% and after 43 days of annealing in air it improved to a 14% loss. The formulated sample consisted of 70 parts by weight of Dow polystyrene, 30 pbw of pentaphenyltrimethyltrisiloxane (Dow Corning DC 705 oil), 2 pbw of p-terphenyl, 0.2 pbw of tetraphenylbutadiene, and 0.5 pbw of UVASIL299LM from Ferro.

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

1993-01-01

95

Unitary scintillation detector and system  

DOEpatents

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

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

1994-01-01

96

Review of Ionospheric Scintillation Models and proposing a Novel Model for Characterizing High Latitude Irregularities  

NASA Astrophysics Data System (ADS)

The study of ionospheric scintillations of radio signal involves a problem of electromagnetic (EM) wave propagation in random media and has been a subject of interest for more than last 5 decades. Some of the representative works are by Booker et. al (1950), Ratcliffe (1956), Wernik and Liu (1975), Yeh and Liu (1982), Secan et. al (1995), Costa and Basu (2002), Rino and Carrano (2011). Many of the scintillation models employ a phase screen model introduced by Rino (1979). Beniguel and Hamel (2011) implemented a global ionospheric scintillation model for equatorial regions showing a good agreement of the model with measurements. Implementing these models in the study of ionospheric scintillations of radio signals at high latitudes could be challenging since the path of satellite signal to ground has a variable angle of incidence, in addition to the complicated geometry of magnetic field lines at high latitude and polar regions, and complex magnetosphere-ionosphere coupling mechanisms creating the irregularities. We have developed a high fidelity 3-dimensional Global Positioning System Ionospheric Scintillation Model (3D-GPSISM) which is a full 3D EM wave propagation model to simulate GPS scintillations in high latitude ionosphere. The results from this model can form a basic framework on the use of inverse method to understand the physics of high latitude irregularities using GPS scintillations. We are using our model and an inverse method for selected scintillation observations during 2010 - 2013 from GPS receivers at South Pole, McMurdo and remote stations on Antarctica in conjunction with ancillary observations from SuperDARN, magnetometers, All Sky Imagers etc. We believe that such inverse method can be used to derive certain characteristics of the irregularity causing the scintillations and further achieve an improved understanding of the physics of high latitude irregularities.

Deshpande, K.; Bust, G. S.; Clauer, C. R.

2013-12-01

97

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

98

3D Printing of Scintillating Materials  

E-print Network

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

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

2014-01-01

99

3D Printing of Scintillating Materials  

E-print Network

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

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

2014-06-15

100

Hygroscopicity Evaluation of Halide Scintillators  

SciTech Connect

A collaborative study of relative hygroscopicity of anhydrous halide scintillators grown at various laboratories is presented. We have developed a technique to evaluate moisture sensitivity of both raw materials and grown crystals, in which the moisture absorption rate is measured using a gravimetric analysis. Degradation of the scintillation performance was investigated by recording gamma-ray spectra and monitoring the photopeak position, count rate and energy resolution. The accompanying physical degradation of the samples exposed to ambient atmosphere was photographically recorded as well. The results were compared with ben

Zhuravleva, M [The University of Tennessee] [The University of Tennessee; Stand, L [The University of Tennessee] [The University of Tennessee; Wei, H [The University of Tennessee] [The University of Tennessee; Hobbs, C. L. [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK); Boatner, Lynn A [ORNL] [ORNL; Ramey, Joanne Oxendine [ORNL] [ORNL; Burger, Arnold [Fisk University, Nashville] [Fisk University, Nashville; Rowe, E [Fisk University, Nashville] [Fisk University, Nashville; Bhattacharya, P. [Fisk University, Nashville] [Fisk University, Nashville; Tupitsyn, E [Fisk University, Nashville] [Fisk University, Nashville; Melcher, Charles L [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK)

2014-01-01

101

Characteristics of High Latitude Ionosphere Scintillations  

NASA Astrophysics Data System (ADS)

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

Morton, Y.

2012-12-01

102

Advantages and Problems of Nanocrystalline Scintillators  

Microsoft Academic Search

Our experiments with nanocrystalline scintillating rare earth oxides and rare earth fluorides have shown that in some cases nanoscopic dimensions provide essential improvement of the most important scintillation parameters: light yield, kinetics of scintillations, radiation hardness, etc. We found that in the range from 20 to 100-nm of the oxide and fluoride particles there are 3 types of layered structures:

N. V. Klassen; V. V. Kedrov; V. N. Kurlov; Yu. A. Ossipyan; S. Z. Shmurak; I. M. Shmyt'ko; G. K. Strukova; N. P. Kobelev; E. A. Kudrenko; O. A. Krivko; A. P. Kiselev; A. V. Bazhenov; T. N. Fursova

2008-01-01

103

Composite scintillators for detection of ionizing radiation  

DOEpatents

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

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

2010-12-28

104

Imaging-Based Screening: Understanding the Controversies  

PubMed Central

Objective The goals of this article are to provide an overview of controversial aspects of imaging-based screening and to elucidate potential risks that may offset anticipated benefits. Conclusion Current controversial topics associated with imaging-based screening include false-positive results, incidental findings, overdiagnosis, radiation risks, and costs. Alongside the benefits of screening, radiologists should be prepared to discuss these additional diagnostic consequences with providers and patients to better guide shared decision making regarding imaging-based screening. PMID:25341132

Lam, Diana L.; Pandharipande, Pari V.; Lee, Janie M.; Lehman, Constance D.; Lee, Christoph I.

2014-01-01

105

An improved scintillation beta spectrometer  

E-print Network

AN IYiiROVED SCINTILLATION BETA SPECTROMETER A Thesis Jimmy Fred McClary Submitted to the Graduate College of Tezas AdM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE January 1964. Ma]or Sub...

McClary, Jimmy Fred

1964-01-01

106

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

107

Formula Optimization of the Jiashitang Scar Removal Ointment and Antiinflammatory Compounds Screening by NF-?B Bioactivity-guided Dual-luciferase Reporter Assay System.  

PubMed

Inflammation plays a role in scar formation; therefore, decreasing inflammation benefits scar removal. Jiashitang scar removal ointment (JST) is a commercially available traditional Chinese medicinal formulation. It is composed of extracts from Carthamus tinctorius L. (Car), Rheum officinale Baill. (Rhe), Salvia miltiorrhiza Beg. (Sal), and Panax notoginseng (Burk.) F.?H. Chen (Pan), which are all herbs with potent antiinflammatory activities. Our aims are to optimize the formula of JST and to elucidate its antiinflammatory active components. Response surface methodology was applied to optimize proportions of the four herb extracts. The antiinflammatory effects were evaluated using in vitro and in vivo models. To screen for active components in this formula, a bioactivity-based ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry analysis was performed. After optimization, the antiinflammatory effects of the new formula were significantly superior to the original one. Screening identified 13 active ingredients: a series of saffiomin, emodin, salvianolic acid, tanshinone, and triterpenoid saponin derivatives. These active ingredients were predicted to exert nuclear factor-?B inhibiting effects through MAPK, PI3K/AKT, and NIK-IKK pathways. In conclusion, the original formula was successfully optimized with more potent antiinflammatory activity. These methods can be applied to researches of other formulas. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25363818

Gao, Jie; Tao, Jin; Zhang, Nannan; Liu, Yanjie; Jiang, Min; Hou, Yuanyuan; Wang, Qian; Bai, Gang

2014-11-01

108

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

109

Activity-screening-guided isolation and purification for vasodilative effects compounds from Radix Astragali by high-speed counter-current chromatography using gradient elution.  

PubMed

The animal models were conducted to activity screening of different ethanol fraction from Radix Astragali. Eluted from the macroporous adsorptive resins, the potential active fraction that had vasodilative effects was isolated and purified by high-speed counter-current chromatography (HSCCC) using gradient elution. The solvent system was composed of chloroform-methanol-acetic acid-water (2?:?1?:?1?:?1, v/v/v/v). The flow rate was 1.0?mL?min(-1) initially and changed to 2.0?mL?min(-1) at 300?min. Four flavonoids named calycosin-7-O-?- D -glycoside (a), formononetin-7-O-?- D -glycoside (b), calycosin (c) and formononetin (d) with purity over 94% were obtained and then identified by (1)H NMR and (13)C NMR. PMID:22624991

Feng, Zu-Fei; Chen, Xiao-Fen; Zhang, Jia; Di, Duo-Long

2013-01-01

110

Cosmic ray scintillations. II - General theory of interplanetary scintillations  

NASA Technical Reports Server (NTRS)

The motion of charged particles in a stochastic magnetic field with nonzero mean is considered via a generalized quasi-linear expansion of Liouville's equation. The general result is an equation relating cosmic ray scintillations to magnetic fluctuations and to cosmic ray gradients. The resonant interaction between particles and the random magnetic field is considered in detail, and the effect of nonlinear terms in the equations is considered. The nonlinear terms are important in damping out initial conditions and in determining conditions near cyclotron resonances. The application of the theory to the propagation of cosmic rays during quiet times in interplanetary space is considered. It is concluded that cosmic ray scintillations in interplanetary space may provide useful information about interplanetary particles and fields and also about nonlinear plasma interactions.

Owens, A. J.

1974-01-01

111

Scintillator diagnostics for the detection of laser accelerated ion beams  

NASA Astrophysics Data System (ADS)

Laser plasma interaction with ultraintense pulses present exciting schemes for accelerating ions. One of the advantages conferred by using a gaseous laser and target is the potential for a fast (several Hz) repetition rate. This requires diagnostics which are not only suited for a single shot configuration, but also for repeated use. We consider several scintillators as candidates for an imaging diagnostic for protons accelerated to MeV energies by a CO2 laser focused on a gas jet target. We have measured the response of chromium-doped alumina (chromox) and polyvinyl toluene (PVT) screens to protons in the 2-8 MeV range. We have calibrated the luminescent yield in terms of photons emitted per incident proton for each scintillator. We also discuss how light scattering and material properties affect detector resolution. Furthermore, we consider material damage and the presence of an afterglow under intense exposures. Our analysis reveals a near order of magnitude greater yield from chromox in response to proton beams at > 8 MeV energies, while scattering effects favor PVT-based scintillators at lower energies.

Cook, N.; Tresca, O.; Lefferts, R.

2014-09-01

112

Toxicology screen  

MedlinePLUS

A toxicology screen refers to various tests to determine the type and approximate amount of legal and illegal drugs ... Toxicology screening is most often done using a blood or urine sample. However, it may be done ...

113

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

NASA Astrophysics Data System (ADS)

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

Zentai, George; Ganguly, Arundhuti; Visrshup, Gary

2014-03-01

114

Scintillation Monitoring Using Asymmetry Index  

NASA Astrophysics Data System (ADS)

Variation in electron density can have significant effect on GNSS signals in terms of propagation delay. Ionospheric scintillation can be caused by rapid change of such delay, specifically, when they last for a longer period of time. Ionospheric irregularities that account for scintillation may vary significantly in spatial range and drift with the background plasma at speeds of 45 to 130 m/sec. These patchy irregularities may occur several times during night, e.g. in equatorial region, with the patches move through the ray paths of the GNSS satellite signals. These irregularities are often characterized as either ‘large scale’ (which can be as large as several hundred km in East-West direction and many times that in the North-South direction) or ‘small scale’ (which can be as small as 1m). These small scale irregularities are regarded as the main cause of scintillation [1,2]. In normal solar activity conditions, the mid-latitude ionosphere is not much disturbed. However, during severe magnetic storms, the aurora oval extends towards the equator and the equator anomaly region may stretched towards poles extending the scintillation phenomena more typically associated with those regions into mid-latitudes. In such stormy conditions, the predicted TEC may deviate largely from the true value of the TEC both at low and mid-latitudes due to which GNSS applications may be strongly degraded. This work is an attempt to analyze ionospheric scintillation (S4 index) using ionospheric asymmetry index [3]. The asymmetry index is based on trans-ionospheric propagation between GPS and LEO satellites in a radio occultation (RO) scenario, using background ionospheric data provided by MIDAS [4]. We attempted to simulate one of the recent geomagnetic storms (NOAA scale G4) occurred over low/mid-latitudes. The storm started on 26 September 2011 at UT 18:00 and lasted until early hours of 27 September 2011. The scintillation data for the storm was taken from an ionospheric station in Cairo, Egypt (lat= 29.8641 °, long= 31.3172 °). It was observed that the level of asymmetry was significantly increased during the main phase of the geomagnetic storm. This was due to the changes in ionization, which in turn produced large gradients along occulted ray path in the ionosphere. A very good correlation was found between the evaluated ionospheric asymmetry index and the S4 scintillation index. Additionally, the correlation between evaluated ionospheric asymmetry and errors related to the RO inversion products such as peak electron density (delta NmF2) and Vertical TEC (delta VTEC) estimates also showed promising results. This work is carried out under the framework of the TRANSMIT project (Training Research and Applications Network to Support the Mitigation of Ionospheric Threats - www.transmit-ionosphere.net). [1]Basu Sa. and Basu Su., (1981), ‘Equatorial Scintillation - A Review’, Journal of Atmospheric and Solar-Terrestrial Physics, 43, p. 473. [2]Davies K., (1990), ‘Ionospheric Radio’, IEEE Electromagnetic Waves Series 31, Peter Peregrinus Ltd. [3]Spencer, P., Mitchell, C.N., (2007) ‘Imaging of fast moving electron-density structures in the polar cap’, Annals of Geophysics, vol. 50, no. 3, pp. 427-434. [4]Shaikh, M.M., Notarpietro, R., Nava, B., (2013) ‘The Impact of Spherical Symmetry Assumption on Radio Occultation Data Inversion in the Ionosphere: An Assessment Study’, Advances in Space Research, doi: http://dx.doi.org/10.1016/j.asr.2013.10.025.

Shaikh, Muhammad Mubasshir; Mahrous, Ayman; Abdallah, Amr; Notarpietro, Riccardo

115

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 (2.5 mm 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 590 mm, the inner diameter 161 mm. Geometry and granularity of the hodoscope afford a position resolution of about 1.3 mm. 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.; EDDA Collaboration

1999-07-01

116

Buried plastic scintillator muon telescope  

NASA Astrophysics Data System (ADS)

Muon telescopes can have several applications, ranging from astrophysical to solar-terrestrial interaction studies, and fundamental particle physics. We show the design parameters, characterization and end-to-end simulations of a detector composed by a set of three parallel dual-layer scintillator planes, buried at fix depths ranging from 0.30 m to 3 m. Each layer is 4 m2 and is composed by 50 rectangular pixels of 4cm x 2 m, oriented at a 90 deg angle with respect to its companion layer. The scintillators are MINOS extruded polystyrene strips with two Bicron wavelength shifting fibers mounted on machined grooves. Scintillation light is collected by multi-anode PMTs of 64 pixels, accommodating two fibers per pixel. The front-end electronics has a time resolution of 7.5 nsec. Any strip signal above threshold opens a GPS-tagged 2 micro-seconds data collection window. All data, including signal and background, are saved to hard disk. Separation of extensive air shower signals from secondary cosmic-ray background muons and electrons is done offline using the GPS-tagged threefold coincidence signal from surface water cerenkov detectors located nearby in a triangular array. Cosmic-ray showers above 6 PeV are selected. The data acquisition system is designed to keep both, background and signals from extensive air showers for a detailed offline data.

Sanchez, F.; Medina-Tanco, G. A.; D'Olivo, J. C.; et al.

117

Scintillation correction for astronomical photometry on large and extremely large telescopes with tomographic atmospheric reconstruction  

NASA Astrophysics Data System (ADS)

We describe a new concept to correct for scintillation noise on high-precision photometry in large and extremely large telescopes using telemetry data from adaptive optics (AO) systems. Most wide-field AO systems designed for the current era of very large telescopes and the next generation of extremely large telescopes require several guide stars to probe the turbulent atmosphere in the volume above the telescope. These data can be used to tomographically reconstruct the atmospheric turbulence profile and phase aberrations of the wavefront in order to assist wide-field AO correction. If the wavefront aberrations and altitude of the atmospheric turbulent layers are known from this tomographic model, then the effect of the scintillation can be calculated numerically and used to normalize the photometric light curve. We show through detailed Monte Carlo simulation that for an 8 m telescope with a 16 × 16 AO system we can reduce the scintillation noise by an order of magnitude.

Osborn, J.

2015-01-01

118

Ionospheric scintillations of geostationary satellite radio waves  

Microsoft Academic Search

Observations of the scintillations associated with the major geomagnetic storms occurring on July 14 and September 7, 1982 are described. On July 14, relatively weak and long-lasting scintillations were observed on 136-MHz radio wave from the geostationary satellite, ETS-II. These scintillations have features somewhat different from those under geomagnetically quiet conditions: (1) they appeared at local times between 0 h

H. Kumagai; T. Ogawa; T. Hori

1986-01-01

119

Spacecraft Radio Scintillation and Solar System Exploration  

NASA Technical Reports Server (NTRS)

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

Woo, Richard

1993-01-01

120

Recording of relativistic particles in thin scintillators  

SciTech Connect

Results of investigating an assembly of thin scintillators and silicon photomultipliers for registering relativistic particles with the minimum ionization are presented. A high efficiency of registering relativistic particles using an Ej-212 plastic scintillator, BSF-91A wavelength-shifting fiber (Saint-Gobain), and a silicon photomultiplier (Hamamtsu) is shown. The measurement results are used for creating a scintillation hodoscope of the magnetic spectrometer for registering ? quanta in the GlueX experiment.

Tolstukhin, I A.; Somov, Alexander S. [JLAB; Somov, S. V.; Bolozdynya, A. I.

2014-11-01

121

Neutron position-sensitive scintillation detector  

DOEpatents

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

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

1984-01-01

122

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

PubMed Central

Abstract Drug-induced hepatotoxicity is a leading cause of attrition for candidate pharmaceuticals in development. New preclinical screening methods are crucial to predict drug toxicity prior to human studies. Of all in vitro hepatotoxicity models, primary human hepatocytes are considered as ‘the gold standard.’ However, their use is hindered by limited availability and inter-individual variation. These barriers may be overcome by using primary mouse hepatocytes. We used differential in gel electrophoresis (DIGE) to study large-scale protein expression of primary mouse hepatocytes. These hepatocytes were exposed to three well-defined hepatotoxicants: acetaminophen, amiodarone, and cyclosporin A. Each hepatotoxicant induces a different hepatotoxic phenotype. Based on the DIGE results, the mRNA expression levels of deregulated proteins from cyclosporin A-treated cells were also analyzed. We were able to distinguish cyclosporin A from controls, as well as acetaminophen and amiodarone-treated samples. Cyclosporin A induced endoplasmic reticulum (ER) stress and altered the ER-Golgi transport. Moreover, liver carboxylesterase and bile salt sulfotransferase were differentially expressed. These proteins were associated with a protective adaptive response against cyclosporin A-induced cholestasis. The results of this study are comparable with effects in HepG2 cells. Therefore, we suggest both models can be used to analyze the cholestatic properties of cyclosporin A. Furthermore, this study showed a conserved response between primary mouse hepatocytes and HepG2 cells. These findings collectively lend support for use of omics strategies in preclinical toxicology, and might inform future efforts to better link preclinical and clinical research in rational drug development. PMID:23308384

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

2013-01-01

123

Radio wave scintillations at equatorial regions  

NASA Technical Reports Server (NTRS)

Radio waves, passing through the atmosphere, experience amplitude and phase fluctuations know as scintillations. A characterization of equatorial scintillation, which has resulted from studies of data recorded primarily in South America and equatorial Africa, is presented. Equatorial scintillation phenomena are complex because they appear to vary with time of day (pre-and postmidnight), season (equinoxes), and magnetic activity. A wider and more systematic geographical coverage is needed for both scientific and engineering purposes; therefore, it is recommended that more observations should be made at earth stations (at low-geomagnetic latitudes) to record equatorial scintillation phenomena.

Poularikas, A. D.

1972-01-01

124

Neutron Spectrum Unfolding with Organic Scintillators for  

E-print Network

Neutron Spectrum Unfolding with Organic Scintillators for Arms-control Verification by Christopher of Doctor of Philosophy (Nuclear Engineering and Radiological Sciences) in The University of Michigan 2014

Becchetti, Fred

125

Waveshifters and Scintillators for Ionizing Radiation Detection  

SciTech Connect

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

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

2007-12-11

126

Field Guides  

NSDL National Science Digital Library

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

127

Completion of the L3 e.m. calorimeter with a lead-scintillating fibers spaghetti calorimeter  

NASA Astrophysics Data System (ADS)

We report on the test-beam results for three prototype modules of a lead-scintillating fiber ( spaghetti) calorimeter. We studied linearity, energy resolution and light collection. The results are in agreement with expectations from MC simulation. We also report on the studies for the optimal light guide to be used in the final design.

Basti, G.; Boucham, A.; Campanelli, M.; Cecchi, C.; de Notaristefani, F.; Diemoz, M.; Ferroni, F.; Iaciofano, A.; Janssen, B.; Karyotakis, Y.; Lebeau, M.; Lesueur, J.; Longo, E.; Organtini, G.; Tsipolitis, Y.

1995-11-01

128

Correlation of GPS signal fades due to ionospheric scintillation for aviation applications  

NASA Astrophysics Data System (ADS)

Deep and frequent Global Positioning System (GPS) signal fading due to strong ionospheric scintillation is a major concern for GPS-guided aviation in equatorial areas during high solar activity. A GPS aviation receiver may lose carrier tracking lock under deep fading, and a lost channel cannot be used for position calculation until lock is reestablished. Hence, frequent loss of lock due to frequent fading can significantly reduce the availability of GPS aviation. However, the geometric diversity of the satellites can mitigate scintillation impact on GPS aviation depending on the correlation level of deep fades between satellites. This paper proposes a metric to measure the correlation level of two fading channels from the perspective of GPS aviation. Using this metric, the satellite-to-satellite correlation is studied based on real scintillation data. The low satellite-to-satellite correlation shown in this paper envisions notable availability benefit from the geometric diversity of satellites under strong scintillation. In addition, this paper proposes a way to generate correlated fading processes with arbitrary correlation coefficients. Using this correlated fading process model, the availability of Localizer Performance with Vertical guidance (LPV)-200 under severe scintillation scenarios is analyzed. The result emphasizes the importance of a fast reacquisition capability of an aviation receiver after a brief outage, which is not currently mandated by the aviation receiver performance standards.

Seo, Jiwon; Walter, Todd; Enge, Per

2011-05-01

129

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

130

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

131

Gravitational wave scintillation by a stellar cluster  

E-print Network

The diffraction effects on gravitational waves propagating through a stellar cluster are analyzed in the relevant approximation of Fresnel diffraction limit. We find that a gravitational wave scintillation effect - similar to the radio source scintillation effect - comes out naturally, implying that the gravitational wave intensity changes in a characteristic way as the observer moves.

G. Congedo; F. De Paolis; P. Longo; A. A. Nucita; D. Vetrugno

2006-10-27

132

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

133

The most powerful scintillator supernovae detector: LVD  

Microsoft Academic Search

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

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

1992-01-01

134

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.

Irwin Slesnick

2004-01-01

135

Screen Time  

NSDL National Science Digital Library

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

Omsi

2007-01-01

136

Genetic screening  

PubMed Central

Abstract OBJECTIVE To provide a primer for primary care professionals who are increasingly called upon to discuss the growing number of genetic screening services available and to help patients make informed decisions about whether to participate in genetic screening, how to interpret results, and which interventions are most appropriate. QUALITY OF EVIDENCE As part of a larger research program, a wide literature relating to genetic screening was reviewed. PubMed and Internet searches were conducted using broad search terms. Effort was also made to identify the gray literature. MAIN MESSAGE Genetic screening is a type of public health program that is systematically offered to a specified population of asymptomatic individuals with the aim of providing those identified as high risk with prevention, early treatment, or reproductive options. Ensuring an added benefit from screening, as compared with standard clinical care, and preventing unintended harms, such as undue anxiety or stigmatization, depends on the design and implementation of screening programs, including the recruitment methods, education and counseling provided, timing of screening, predictive value of tests, interventions available, and presence of oversight mechanisms and safeguards. There is therefore growing apprehension that economic interests might lead to a market-driven approach to introducing and expanding screening before program effectiveness, acceptability, and feasibility have been demonstrated. As with any medical intervention, there is a moral imperative for genetic screening to do more good than harm, not only from the perspective of individuals and families, but also for the target population and society as a whole. CONCLUSION Primary care professionals have an important role to play in helping their patients navigate the rapidly changing terrain of genetic screening services by informing them about the benefits and risks of new genetic and genomic technologies and empowering them to make more informed choices. PMID:20393090

Andermann, Anne; Blancquaert, Ingeborg

2010-01-01

137

Measurement of imaging properties of scintillating fiber optic plate  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

138

Scintillation Breakdowns in Chip Tantalum Capacitors  

NASA Technical Reports Server (NTRS)

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 dielectric and prevents short-circuit failures. Typically, this type of breakdown has no immediate catastrophic consequences and is often considered as nuisance rather than a failure. Scintillation breakdowns likely do not affect failures of parts under surge current conditions, and so-called "proofing" of tantalum chip capacitors, which is a controllable exposure of the part after soldering to voltages slightly higher than the operating voltage to verify that possible scintillations are self-healed, has been shown to improve the quality of the parts. However, no in-depth studies of the effect of scintillations on reliability of tantalum capacitors have been performed so far. KEMET is using scintillation breakdown testing as a tool for assessing process improvements and to compare quality of different manufacturing lots. Nevertheless, the relationship between failures and scintillation breakdowns is not clear, and this test is not considered as suitable for lot acceptance testing. In this work, scintillation breakdowns in different military-graded and commercial tantalum capacitors were characterized and related to the rated voltages and to life test failures. A model for assessment of times to failure, based on distributions of breakdown voltages, and accelerating factors of life testing are discussed.

Teverovsky, Alexander

2008-01-01

139

Sepsis screening.  

PubMed

NHS Education for Scotland has, in collaboration with the Scottish Patient Safety Programme, made the national early warning score (NEWS) and sepsis screening tool available as a smartphone app. The app provides: a NEWS calculator to alert clinicians to deteriorating patients and acute illness; a sepsis screening tool for the prompt recognition and initiation of treatment of patients with sepsis; an outline of the Sepsis 6 care bundle; and an algorithm to help identify organ dysfunction, severe sepsis, septic shock and when to escalate care. Go to tinyurl.com/sepsis-screening to download the app. PMID:25355121

2014-10-30

140

New Organic Scintillators for Neutron Detection  

NASA Astrophysics Data System (ADS)

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 10B—doped for thermal neutron detection) 3He 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; Szczee?niak, Tomasz

2010-01-01

141

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

142

MRSA Screening  

MedlinePLUS

... Was this page helpful? Formal name: Methicillin resistant Staphylococcus aureus Screening Related tests: Wound Culture At a Glance ... Why Get Tested? To determine your methicillin resistant Staphylococcus aureus (MRSA) carrier status When to Get Tested? When ...

143

TORCH screen  

MedlinePLUS

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

144

Vision Screening  

MedlinePLUS

... regular well care office visits. In addition, many day care programs, churches, schools and health departments offer vision ... addition to vision screening that is offered at day care, school or church. In some states a documented ...

145

Ripcorder Screen  

NSDL National Science Digital Library

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

2012-11-06

146

Ionospheric scintillation in the polar cap  

NASA Astrophysics Data System (ADS)

The state of knowledge of ionospheric scintillation in the polar cap today is compared to the state of knowledge of the equatorial ionosphere a decade ago. Recent airborne measurements made by a team of Avionics Laboratory and Air Force Geophysics Laboratory personnel indicate that the occurrence of scintillation depends on the season and solar flux density. Little dependence of scintillation on magnetic index of day is noted. Nearly simultaneous onsets on scintillation at two aircraft locations 100 km apart indicate a very high ionospheric irregularity velocity in the polar cap. Ionospheric irregularity flow in the polar cap is seen as being away from the noontime auroral oval toward the midnight sector with a two-cell flow back toward the noon sector.

Johnson, A. L.

147

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

148

Scintillation Properties of Praseodymium Activated Single Crystals  

Microsoft Academic Search

Scintillation properties of LuAG:Pr grown by Furukawa Co. Ltd., Japan, have been studied. The best crystals display light outputs up to 19000 ph\\/MeV and an energy resolution of 4.6% at 662 keV. The scintillation yield is found to be a function of size and temperature of the sample; it can be enhanced by 40% upon heating to 450 K. Radioluminescence

Winicjusz Drozdowski; Pieter Dorenbos; J. T. M. de Haas; R. Drozdowska; A. Owens; K. Kamada; K. Tsutsumi; Y. Usuki; T. Yanagida; A. Yoshikawa

2008-01-01

149

Ternary liquid scintillator for optical fiber applications  

DOEpatents

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

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

1982-01-01

150

Real-time volumetric scintillation dosimetry  

NASA Astrophysics Data System (ADS)

The goal of this brief review is to review the current status of real-time 3D scintillation dosimetry and what has been done so far in this area. The basic concept is to use a large volume of a scintillator material (liquid or solid) to measure or image the dose distributions from external radiation therapy (RT) beams in three dimensions. In this configuration, the scintillator material fulfills the dual role of being the detector and the phantom material in which the measurements are being performed. In this case, dose perturbations caused by the introduction of a detector within a phantom will not be at issue. All the detector configurations that have been conceived to date used a Charge-Coupled Device (CCD) camera to measure the light produced within the scintillator. In order to accurately measure the scintillation light, one must correct for various optical artefacts that arise as the light propagates from the scintillating centers through the optical chain to the CCD chip. Quenching, defined in its simplest form as a nonlinear response to high-linear energy transfer (LET) charged particles, is one of the disadvantages when such systems are used to measure the absorbed dose from high-LET particles such protons. However, correction methods that restore the linear dose response through the whole proton range have been proven to be effective for both liquid and plastic scintillators. Volumetric scintillation dosimetry has the potential to provide fast, high-resolution and accurate 3D imaging of RT dose distributions. Further research is warranted to optimize the necessary image reconstruction methods and optical corrections needed to achieve its full potential.

Beddar, S.

2015-01-01

151

Crystal growth and scintillation properties of strontium iodide scintillators  

SciTech Connect

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

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

2009-06-01

152

Development of Novel Polycrystalline Ceramic Scintillators  

SciTech Connect

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

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

2008-01-01

153

GPS phase scintillation correlated with auroral forms  

NASA Astrophysics Data System (ADS)

The disruption of radio wave propagation due to rapid changes in electron density caused by auroral precipitation has been observed for several decades. In a few cases the disruption of GPS signals has been attributed to distinct auroral arcs [Kintner, 2007; Garner, 2011], but surprisingly there has been no systematic study of the characteristics of the auroral forms that cause GPS scintillation. In the Fall of 2012 ASTRA deployed four CASES GPS receivers at UAF observatories in Alaska (Kaktovik, Fort Yukon, Poker Flat and Gakona) specifically to address the effects of auroral activity on the high latitude ionosphere. We have initiated an analysis that compares the phase scintillation, recorded at high cadence, with filtered digital all-sky camera data to determine the auroral morphology and electron precipitation parameters that cause scintillation. From correlation studies from a single site (Poker Flat), we find that scintillation is well correlated with discrete arcs that have high particle energy flux (power per unit area), and not as well correlated with pulsating forms which typically have high characteristic energy, but lower energy flux . This indicates that the scintillation is correlated with the magnitude of the change in total electron density as expected. We will also report on ongoing work where we correlate the scintillation from the Fort Yukon receiver with the all-sky images at Poker Flat to determine the altitude that produces the greatest disturbance. These studies are aimed at a model that can predict the expected local disturbance to navigation due to auroral activity.

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

2013-12-01

154

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

E-print Network

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 \\hbox{$\\approx 10^6$} capillaries with \\hbox{20$-$25 $\\mu$m} diameter and \\hbox{0.9$-$1.8 m} length, have been tested, and a spatial resolution of the order of \\hbox{20$-$40 $\\mu$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 $\\sim$ 8 hits/mm at the readout window, and \\hbox{$\\sim$ 3 ...

Annis, P; Benussi, L; Bruski, N; Buontempo, S; Currat, C; D'Ambrosio, N; Van Dantzig, R; Dupraz, J P; Ereditato, A; Fabre, Jean-Paul; Fanti, V; Feyt, J; Frekers, D; Frenkel, A; Galeazzi, F; Garufi, F; Goldberg, J; Golovkin, S V; Gorin, A M; Grégoire, G; Harrison, K; Höpfner, 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, Yu P; Rondeshagen, D; Siegmund, W P; Tyukov, V E; Van Beek, G; Vasilchenko, V G; Vilain, P; Visschers, J L; Wilquet, G; Winter, Klaus; Wolff, T; Wörtche, H J; Wong, H; Zimyn, K V

2000-01-01

155

Modeling of scintillation camera systems.  

PubMed

Despite their widespread use, the satisfactory modeling of scintillation camera systems has remained difficult. Although the resolving time and deadtime T of a nonparalyzable counter are identical and also invariable, a distinction needs to be made between the fixed resolving time tau0 and the variable deadtime tau of a paralyzable counter. It is shown here that tau = tau0(e(n) - 1)/n, where n = Ntau0 = N/Nmax is the normalized input rate and N the absolute input rate. The normalized output rate, r = Rtau0, where R is the absolute output rate, has a maximum value r(max) = 1/e approximately 0.368 at the input rate n(max) = 1, where tau = tau0(e - 1) approximately 1.718tau0. It is also shown that the response of a system of nonparalyzable and paralyzable components at all input rates is determined by just the dominant nonparalyzable and paralyzable components in the system, the response at any particular input rate being that of the component with the higher of the two deadtimes T or tau. A system can be purely paralyzable (kT = T/tau0 < or = 1), combined paralyzable/nonparalyzable (1 < kT < or = 1.718), or essentially nonparalyzable (kT > 1.718), the combined paralyzable/nonparalyzable system having a lower nonparalyzable (T > tau) and an upper paralyzable (tau > T) operating range separated by a threshold input rate n(t) = ln(1 + kTn(t)) at which tau = T. A highly accurate and explicit expression for n(t) has also been derived. In the essentially nonparalyzable case, the system operates as nonparalyzable all the way up to the system's peak response point, which may occur at or above n(max) = 1. A two-component system with kT > 1 can also be described mathematically as nonparalyzable using r = n/(1 + k(tau)n), where k(tau) = tau/tau0 = kT for n < or = n(t), and k(tau) = (e(n) - 1)/n for n > or = n(t), or as paralyzable using r = ne(-nk0) with k0 = [ln(1 + kTn)]/n for n < or = n(t) and k0 = 1 for n > or = n(t). These alternative descriptions will be of considerable importance in the measurement of T and tau0 for such systems. The model described is able to account fully for the three different operating modes possible with scintillation camera systems. PMID:10435541

Woldeselassie, T

1999-07-01

156

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

157

15-March 2007 1 A Scintillating Fibre TrackerA Scintillating Fibre Tracker  

E-print Network

SFT 1SFT 1 SFT 2SFT 2 Weilin Yu, DPG Frühjahrstagung,Gie�en #12;15-March 2007 11 Scintillating Fibre Tracker(SFT) Built by JLU Giessen 2 cylinders of 2 X 2 layers, 100 stereo angle 1 mm Kuraray fibres Scintillating Fibre Tracker(SFT) Momentum measured in full azimuthal angle and reconstructed by bending 1 Tesla

158

Neutron guide  

DOEpatents

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

Greene, Geoffrey L. (Los Alamos, NM)

1999-01-01

159

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

160

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

161

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

SciTech Connect

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

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

2011-07-01

162

Review on photonic crystal coatings for scintillators  

NASA Astrophysics Data System (ADS)

The amount of light and its time distribution are key factors determining the performance of scintillators when used as radiation detectors. However most inorganic scintillators are made of heavy materials and suffer from a high index of refraction which limits light extraction efficiency. This increases the path length of the photons in the material with the consequence of higher absorption and tails in the time distribution of the extracted light. Photonic crystals are a relatively new way of conquering this light extraction problem. Basically they are a way to produce a smooth and controllable index matching between the scintillator and the output medium through the nanostructuration of a thin layer of optically transparent high index material deposited at the coupling face of the scintillator. Our review paper discusses the theory behind this approach as well as the simulation details. Furthermore the different lithography steps of the production of an actual photonic crystal sample will be explained. Measurement results of LSO scintillator pixels covered with a nanolithography machined photonic crystal surface are presented together with practical tips for the further development and improvement of this technique.

Knapitsch, Arno; Lecoq, Paul

2014-11-01

163

Thallium bromide photodetectors for scintillation detection  

NASA Astrophysics Data System (ADS)

A wide bandgap compound semiconductor, TlBr, has been investigated as a blue sensitive photodetector material for scintillation detection. The TlBr photodetectors have been fabricated from the TlBr crystals grown by the TMZ method using materials purified by many pass zone refining. The performance of the photodetectors has been evaluated by measuring their leakage current, quantum efficiency, spatial uniformity, direct X-ray detection and scintillation detection characteristics. The photodetectors have shown high quantum efficiency for the blue wavelength region and high spatial uniformity for their optical response. In addition, good direct X-ray detection characteristics with an energy resolution of 4.5 keV FWHM for 22 keV X-rays from a 109Cd radioactive source have been obtained. Detection of blue scintillation from GSO and LSO scintillators irradiated with a 22Na radioactive source has been done successfully by using the photodetectors at room temperature. A clear full-energy peak for 511 keV ?-rays has been obtained with the TlBr photodetector coupled to the LSO scintillator with an energy resolution of 40% FWHM.

Hitomi, K.; Muroi, O.; Shoji, T.; Hiratate, Y.; Ishibashi, H.; Ishii, M.

2000-07-01

164

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

PubMed

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

Spanoudaki, V Ch; Levin, C S

2011-02-01

165

Vision Screening  

NASA Technical Reports Server (NTRS)

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

1993-01-01

166

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

167

The Long Wavelength Array (LWA) and Interplanetary Scintillation (IPS)  

E-print Network

The Long Wavelength Array (LWA) and Interplanetary Scintillation (IPS) Patrick C. Crane 12 January scintillation (IPS) is the random fluctuation in the intensity and phase of electromagnetic waves passing

Ellingson, Steven W.

168

Glass and phosphor scintillators for x-ray imaging  

SciTech Connect

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

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

1998-11-09

169

Photovoltaic nanocrystal scintillators hybridized on Si solar cells  

E-print Network

Photovoltaic nanocrystal scintillators hybridized on Si solar cells for enhanced conversion@bilkent.edu.tr Abstract: We propose and demonstrate semiconductor nanocrystal based photovoltaic scintillators integrated on solar cells to enhance photovoltaic device parameters including spectral responsivity, open circuit

Demir, Hilmi Volkan

170

On the scintillation efficiency of carborane-loaded liquid scintillators for thermal neutron detection  

NASA Astrophysics Data System (ADS)

The scintillation efficiency in response to thermal neutrons was studied by loading different concentrations of carborane (0-8.5 wt%) and naphthalene (0 and 100 g/L) in five liquid organic scintillators. The sample was characterized in Pb and Cd shields under the irradiation of the thermal neutrons from a 252Cf source. A method was developed to extract the net neutron response from the pulse-height spectra. It was found that the order of scintillation efficiencies for both ?-rays and thermal neutrons is as follows: diisopropylnaphthalene>toluene (concentrated solutes)>toluene~pseudocumene~m-xylene. The quench constants, obtained by fitting the Stern-Volmer model to the plots of light output versus carborane concentration, are in the range of 0.35-1.4 M-1 for all the scintillators. The Birks factors, estimated using the specific energy loss profiles of the incident particles, are in the range of 9.3-14 mg cm-2 MeV-1 for all the samples. The light outputs are in the range of 63-86 keV electron equivalents (keVee) in response to thermal neutrons. Loading naphthalene generally promotes the scintillation efficiency of the scintillator with a benzene derivative solvent. Among all the scintillators tested, the diisopropylnaphthalene-based scintillator shows the highest scintillation efficiency, lowest Birks factor, and smallest quench constants. These properties are primarily attributed to the double fused benzene-ring structure of the solvent, which is more efficient to populate to the excited singlet state under ionizing radiation and to transfer the excitation energy to the fluorescent solutes.

Chang, Zheng; Okoye, Nkemakonam C.; Urffer, Matthew J.; Green, Alexander D.; Childs, Kyle E.; Miller, Laurence F.

2015-01-01

171

Ytterbium-based compounds as fast and dense inorganic scintillators  

Microsoft Academic Search

The recent observation of UV scintillation in mixed yttrium\\/ytterbium aluminium garnets opened the field of investigation to a new class of scintillating crystals. Their interesting luminescence properties make them very attractive not only for solar neutrino spectroscopy as ytterbium containing detector material, but also for radiation detection in general, as dense, fast and efficient scintillators. Studies of charge transfer luminescence

Rémi Chipaux; Michel Cribier; Christophe Dujardin; Nicolas Garnier; Natacha Guerassimova; Jacques Mallet; Jean-Pierre Meyer; Christian Pédrini; Ashot G. Petrosyan

2001-01-01

172

A high resolution scintillating fiber gamma-ray telescope  

Microsoft Academic Search

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

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

1989-01-01

173

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

174

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

175

Application of the Strong Scatter Theory to the Interpretation of Ionospheric Scintillation Measurements along Geostationary Satellite Links at VHF and L-band  

NASA Astrophysics Data System (ADS)

In a previous work, we demonstrated that ionospheric turbulence parameters may be inferred from amplitude scintillations well into in the strong scatter regime [Carrano et al., International Journal of Geophysics, 2012]. This technique, called Iterative Parameter Estimation (IPE), uses the strong scatter theory and numerical inversion to estimate the parameters of an ionospheric phase screen (turbulent intensity, phase spectral index, and irregularity zonal drift) consistent with the observed scintillations. The optimal screen parameters are determined such that the theoretical intensity spectrum on the ground best matches the measured intensity spectrum in a least squares sense. We use this technique to interpret scintillation measurements collected during a campaign at Ascension Island (7.96°S, 14.41°W) in March 2000, led by Santimay Basu and his collaborators from Air Force Research Laboratory. Geostationary satellites broadcasting radio signals at VHF and L-band were monitored along nearly co-linear links, enabling a multi-frequency analysis of scintillations with the same propagation geometry. The VHF data were acquired using antennas spaced in the magnetic east-west direction, which enabled direct measurement of the zonal irregularity drift. We show that IPE analysis of the VHF and L-Band scintillations, which exhibited very different statistics due to the wide frequency separation, yields similar estimates of the phase screen parameters that specify the disturbed ionospheric medium. This agreement provides confidence in our phase screen parameter estimates. It also suggests a technique for extrapolating scintillation measurements to frequencies other than those observed that is valid in the case of strong scatter. We find that IPE estimates of the zonal irregularity drift, made using scintillation observations along single space-to-ground link, are consistent with those measured independently using the spaced antenna technique. This encouraging result suggests one may measure the zonal irregularity drift at scintillation monitoring stations equipped with only a single channel receiver, so that the spaced-antenna technique cannot be employed. We noted that the scintillation index (S4) at L-band commonly exceeded that at VHF early in the evening when the irregularities were most intense, followed by one or more reversals of this trend at later local times as aging irregularities decayed and newly formed bubbles drifted over the station. We use the strong scatter theory to explain this perhaps counter-intuitive situation (one would normally expect a higher S4 at the lower frequency) in terms of strong refractive focusing.

Carrano, C. S.; Groves, K. M.; Basu, S.; Mackenzie, E.; Sheehan, R. E.

2013-12-01

176

Bird Guide  

NSDL National Science Digital Library

This activity is intended to familiarize learners with native Houston birds, introduce learners to tools biologists use in the field, and to enhance their observation skills. In this activity, learners will create a field guide based on native Houston birds and will use this field guide to identify birds at school and home. The lesson guide includes background information, questions to ask, extensions and resources.

Houston, Children'S M.

2011-01-01

177

Scintillating fiber detector performance, detector geometries, trigger, and electronics issues for scintillating fiber tracking  

SciTech Connect

Scintillating Fiber tracking technology has made great advances and has demonstrated great potential for high speed charged particle tracking and triggering. The small detector sizes and fast scintillation fluors available make them very promising for use at high luminosity experiments at today`s and tomorrow`s colliding and fixed target experiments where high rate capability is essential. This talk will discuss the current state of Scintillating fiber performance and current Visual Light Photon Counter (VLPC) characteristics. The primary topic will be some of the system design and integration issues which should be considered by anyone attempting to design a scintillating fiber tracking system which includes a high speed tracking trigger. Design. constraints placed upon the detector system by the electronics and mechanical sub-systems will be discussed. Seemingly simple and unrelated decisions can have far reaching effects on overall system performance. SDC and DO example system designs will be discussed.

Baumbaugh, A.E.

1994-06-01

178

General considerations for SSC scintillator calorimeters (For the scintillator general subgroup)  

SciTech Connect

The Scintillator Calorimetry group divided into three subgroups: a conventional uranium and plate design ala ZEUS, fiber design, and a group on general considerations. The considerations of the third group are reported here on geometrical and technical issues. 1 fig.

Nodulman, L.

1989-01-01

179

A focusing gas scintillation proportional counter  

NASA Technical Reports Server (NTRS)

An improved large-area gas scintillation proportional counter has been built, suitable for use in X-ray astronomy. This counter employs electron focusing in a drift region to achieve uniform response. It is shown that a window area of 60 sq cm and a spectral resolution of 10% fwhm or better at 5.9 keV can be obtained.

Anderson, D. F.; Bodine, O. H.; Novick, R.; Wolff, R. S.

1977-01-01

180

A mobile antineutrino detector with plastic scintillators  

E-print Network

We propose a new type segmented antineutrino detector made of plastic scintillators for the nuclear safeguard application. A small prototype was built and tested to measure background events. A satisfactory unmanned field operation of the detector system was demonstrated. Besides, a detailed Monte Carlo simulation code was developed to estimate the antineutrino detection efficiency of the detector.

Yasuhiro Kuroda; Shugo Oguri; Yo Kato; Ryoko Nakata; Yoshizumi Inoue; Chikara Ito; Makoto Minowa

2012-06-28

181

Progress in studying scintillator proportionality: Phenomenological model  

SciTech Connect

We present a model to describe the origin of non-proportional dependence of scintillator light yield on the energy of an ionizing particle. The non-proportionality is discussed in terms of energy relaxation channels and their linear and non-linear dependences on the deposited energy. In this approach, the scintillation response is described as a function of the deposited energy deposition and the kinetic rates of each relaxation channel. This mathematical framework allows both a qualitative interpretation and a quantitative fitting representation of scintillation non-proportionality response as function of kinetic rates. This method was successfully applied to thallium doped sodium iodide measured with SLYNCI, a new facility using the Compton coincidence technique. Finally, attention is given to the physical meaning of the dominant relaxation channels, and to the potential causes responsible for the scintillation non-proportionality. We find that thallium doped sodium iodide behaves as if non-proportionality is due to competition between radiative recombinations and non-radiative Auger processes.

Bizarri, Gregory; Cherepy, Nerine; Choong, Woon-Seng; Hull, Giulia; Moses, William; Payne, Sephen; Singh, Jai; Valentine, John; Vasilev, Andrey; Williams, Richard

2009-04-30

182

Performance of Water-based Liquid Scintillator  

NASA Astrophysics Data System (ADS)

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

Beznosko, Dmitriy

2013-04-01

183

Temperature dependence of BCF plastic scintillation detectors  

PubMed Central

We examined temperature dependence in plastic scintillation detectors (PSDs) made of BCF-60 or BCF-12 scintillating fiber coupled to optical fiber with cyanoacrylate. PSDs were subjected to a range of temperatures using a temperature-controlled water bath and irradiated at each temperature while either the dose was measured using a CCD camera or the spectral output was measured using a spectrometer. The spectrometer was used to examine the intensity and spectral distribution of scintillation light emitted by the PSDs, Cerenkov light generated within the PSD, and light transmitted through an isolated optical coupling. BCF-60 PSDs exhibited a 0.50% decrease and BCF-12 PSDs a 0.09% decrease in measured dose per °C increase, relative to dose measured at 22°C. Spectrometry revealed that the total intensity of the light generated by BCF-60 and BCF-12 PSDs decreased by 0.32% and 0.13%, respectively, per °C increase. The spectral distribution of the light changed slightly with temperature for both PSDs, accounting for the disparity between the change in measured dose and total light output. The generation of Cerenkov light was temperature independent. However, light transmitted through optical coupling between the scintillator and the optical fiber also exhibited temperature dependence. PMID:23574889

Wootton, Landon; Beddar, Sam

2013-01-01

184

THE SCINTILLATION COUNTER PHYSICS 359E  

E-print Network

kinetic energy eventually appears as light are fairly complex. No attempt will be made to discuss employ inorganic scintillators which convert the kinetic energy of 15 keV electrons to visible light- cathode, and these electrons are then accelerated through a potential difference of a few hundred volts

Landstreet, John D.

185

Magnetic fields and SDC endcap scintillator performance  

SciTech Connect

Many detectors designed to operate in colliders contain both magnetic fields, usually solenoids, and scintillators. The former is known to influence the operation of the latter. A first look is taken in this note at the implications of that influence for the SDC detector.

Green, D.

1993-01-01

186

Prospects for dense, infrared emitting scintillators  

SciTech Connect

The authors present results from an ongoing search for inorganic scintillators for x- and gamma-ray detection. They measure the scintillation properties (luminous efficiency, decay time, and emission wavelength) of powdered samples excited by brief x-ray pulses. To find scintillators that are compatible with silicon photodetectors, they have tested over 1,100 samples using a photomultiplier tube with a GaAs:Cs photocathode, which is sensitive to 200--950 nm emissions. Optical filters are used to block emissions that are observable with bialkali PMTs. Several lanthanide and transition metal ions, molecular complexes, and II-VI compounds are known to have strong emissions at wavelengths > 500 nm. They find that several compounds exhibit emission intensities comparable to commercial phosphors in the 600--900 nm range, including Eu and Sm doped LuPO{sub 4}, ScPO{sub 4}, and YPO{sub 4}. Significant emissions are also observed from Tb, Dy, Er, Pr, and Tm doped phosphates, as well as several intrinsic compounds, notably Hg{sub 2}Cl{sub 2}. Scintillation characteristics of promising compounds (in powdered or small crystal form) are presented.

Moses, W.W.; Weber, M.J.; Derenzo, S.E.; Perry, D.; Berdahl, P. [Lawrence Berkeley National Lab., CA (United States)] [Lawrence Berkeley National Lab., CA (United States); Boatner, L.A. [Oak Ridge National Lab., TN (United States)] [Oak Ridge National Lab., TN (United States)

1998-06-01

187

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, Fuxi

1999-10-01

188

Development of tracking detectors based on capillaries with liquid scintillator  

NASA Astrophysics Data System (ADS)

Capillaries with a liquid scintillator used for high resolution tracking detectors have been investigated. The highest scintillation efficiency, 1.5 times higher than that of a standard polystyrene scintillator, has been attained for the solution of 1-methylnaphthalene with pyrasoline type dye MDP. The time properties of this liquid scintillator and locality of light emission have been studied. Light attenuations in quartz capillaries of different diameters have been measured. For the optimal concentration of MDP the attenuation lengths for capillaries of 30 and 60 ?m in diameter were 41 cm and 53 cm, respectively. For high resolution tracking detectors capillaries with a liquid scintillator are quite competitive with plastic fibres.

Golovkin, S. V.; Gorin, A. M.; Kulichenko, A. V.; Kushnirenko, A. E.; Peresypkin, A. I.; Pyshchev, A. I.; Rykalin, V. I.; Zaichenko, A. A.

1991-07-01

189

Radioligand binding to nanodisc-reconstituted membrane transporters assessed by the scintillation proximity assay.  

PubMed

The scintillation proximity assay is a powerful technique for measuring radioligand binding to membrane transporters and has become an integral part of high-throughput drug discovery screening efforts. Here we adapt the method for use with purified LeuT, a prokaryotic secondary transporter, reconstituted into phospholipid bilayer nanodiscs. This application surmounts potential challenges with background interference from endogenously expressed proteins, aggregation and loss of binding activity often accompanying detergent solubilization from native cell membranes, and heterogeneity in size and transporter orientation, where at least some ligand binding sites are inaccessible, associated with reconstitution into lipid vesicles. PMID:24344975

Nasr, Mahmoud L; Singh, Satinder K

2014-01-14

190

Radioligand Binding to Nanodisc-reconstituted Membrane Transporters by Scintillation Proximity Assay  

PubMed Central

The scintillation proximity assay (SPA) is a powerful technique for measuring radioligand binding to membrane transporters and has become an integral part of high-throughput drug discovery screening efforts. Here we adapt the method for use with purified LeuT, a prokaryotic secondary transporter, reconstituted into phospholipid bilayer nanodiscs. This application surmounts potential challenges with background interference from endogenously-expressed proteins; aggregation and loss of binding activity often accompanying detergent solubilization from native cell membranes; and heterogeneity in size and transporter orientation, where at least some ligand binding sites are inaccessible, associated with reconstitution into lipid vesicles. PMID:24344975

Nasr, Mahmoud L.; Singh, Satinder K.

2014-01-01

191

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

SciTech Connect

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

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

2013-07-15

192

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

PubMed

Barium fluoride (BaF2) is an inorganic scintillation material used for the detection of X?gamma radiation due to its relatively high density, equivalent atomic number, radiation hardness, and high luminescence. BaF2 has a potential capacity to be used in gamma ray timing experiments due to the prompt decay emission components. It is known that the light output from BaF2 has three decay components: two prompt of those at approximately 195 nm and 220 nm with a decay constant around 600-800 ps and a more intense, slow component at approximately 310 nm with a decay constant around 630 ns which hinders fast timing experiments. We report here the development of a fast radiation detector based on a BaF2 scintillation crystal employing a special optical filter device, a multiple reflection multi-path ultraviolet region short-wavelength pass light guides (MRMP-short pass filter) by using selective reflection technique, for which the intensity of the slow component is reduced to less than 1%. The methods used for this study provide a novel way to design radiation detector by utilizing scintillation crystal with several emission bands. PMID:23902059

Han, Hetong; Zhang, Zichuan; Weng, Xiufeng; Liu, Junhong; Guan, Xingyin; Zhang, Kan; Li, Gang

2013-07-01

193

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

NASA Astrophysics Data System (ADS)

Barium fluoride (BaF2) is an inorganic scintillation material used for the detection of X/gamma radiation due to its relatively high density, equivalent atomic number, radiation hardness, and high luminescence. BaF2 has a potential capacity to be used in gamma ray timing experiments due to the prompt decay emission components. It is known that the light output from BaF2 has three decay components: two prompt of those at approximately 195 nm and 220 nm with a decay constant around 600-800 ps and a more intense, slow component at approximately 310 nm with a decay constant around 630 ns which hinders fast timing experiments. We report here the development of a fast radiation detector based on a BaF2 scintillation crystal employing a special optical filter device, a multiple reflection multi-path ultraviolet region short-wavelength pass light guides (MRMP-short pass filter) by using selective reflection technique, for which the intensity of the slow component is reduced to less than 1%. The methods used for this study provide a novel way to design radiation detector by utilizing scintillation crystal with several emission bands.

Han, Hetong; Zhang, Zichuan; Weng, Xiufeng; Liu, Junhong; Guan, Xingyin; Zhang, Kan; Li, Gang

2013-07-01

194

A Homogeneous Enzyme Fragment Complementation Cyclic AMP Screen for GPCR Agonists  

Microsoft Academic Search

In the new high-throughput screening (HTS) campaign, receptor functional assays, 3?,5?-cyclic adenosine monophosphate (cAMP), intracellular [Ca2+]i, phosphatidylinositol turnover, and reporter-based assays are being used as primary screens as they are now developed as homogeneous and automation-friendly assays. FlashPlate assay and scintillation proximity assay using radiolabeled cAMP have been used for measuring cAMP. A nonradioactive homogeneous HTS assay using HitHunter™ enzyme

Rajasree Golla; Ramakrishna Seethala

2002-01-01

195

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

196

Nonproportionality of Scintillator Detectors: Theory and Experiment  

SciTech Connect

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

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

2009-08-17

197

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

198

A High-Throughput Scintillation Proximity-Based Assay for Human DNA Ligase IV  

PubMed Central

Abstract Ionizing radiation (IR) and certain chemotherapeutic drugs are designed to generate cytotoxic DNA double-strand breaks (DSBs) in cancer cells. Inhibition of the major DSB repair pathway, nonhomologous end joining (NHEJ), will enhance the cytotoxicity of these agents. Screening for inhibitors of the DNA ligase IV (Lig4), which mediates the final ligation step in NHEJ, offers a novel target-based drug discovery opportunity. For this purpose, we have developed an enzymatic assay to identify chemicals that block the transfer of [?-33P]-AMP from the complex Lig4-[?-33P]-AMP onto the 5? end of a double-stranded DNA substrate and adapted it to a scintillation proximity assay (SPA). A screen was performed against a collection of 5,280 compounds. Assay statistics show an average Z? value of 0.73, indicative of a robust assay in this SPA format. Using a threshold of >20% inhibition, 10 compounds were initially scored as positive hits. A follow-up screen confirmed four compounds with IC50 values ranging from 1 to 30??M. Rabeprazole and U73122 were found to specifically block the adenylate transfer step and DNA rejoining; in whole live cell assays, these compounds were found to inhibit the repair of DSBs generated by IR. The ability to screen and identify Lig4 inhibitors suggests that they may have utility as chemo- and radio-sensitizers in combination therapy and provides a rationale for using this screening strategy to identify additional inhibitors. PMID:22192310

Tseng, Hui-Min; Shum, David; Bhinder, Bhavneet; Escobar, Sindy; Veomett, Nicholas J.; Tomkinson, Alan E.; Gin, David Y.

2012-01-01

199

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

200

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

201

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

202

Scintillation detectors of Alborz-I experiment  

NASA Astrophysics Data System (ADS)

A new air shower experiment of the Alborz Observatory, Alborz-I, located at the Sharif University of Technology, Iran, will be constructed in near future. An area of about 30×40 m2 will be covered by 20 plastic scintillation detectors (each with an area of 50×50 cm2). A series of experiments have been performed to optimize the height of light enclosures of the detectors for this array and the results have been compared to an extended code simulation of these detectors. Operational parameters of the detector obtained by this code are cross checked by the Geant4 simulation. There is a good agreement between the extended-code and Geant4 simulations. We also present further discussions on the detector characteristics, which can be applicable for all scintillation detectors with a similar configuration.

Pezeshkian, Yousef; Bahmanabadi, Mahmud; Abbasian Motlagh, Mehdi; Rezaie, Masume

2015-02-01

203

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

204

Interplanetary scintillation and Jovian DAM emission  

NASA Astrophysics Data System (ADS)

The influence of interplanetary scintillations (IPS) on Jovian decametric (DAM) emission (10-40 MHz) is studied on broad-band dynamic spectra, for the whole range of solar elongations. L-bursts are confirmed to be the result of IPS, and it is shown that they are broad-band bursts. This implies that IPS are correlated on the whole frequency range of observation. It is concluded from observations at conjunction that the intrinsic time scale of Jovian emission is either some milliseconds (S-bursts) or some minutes (arcs). On the other hand, when the elongation is about 130 deg east, a clear decrease in scintillation appears, which has already been observed by Erskine (1976). It is shown that this is a permanent feature of IPS. It could be interpreted as an effect of the interplanetary magnetic field in IPS.

Genova, F.; Leblanc, Y.

1981-05-01

205

Plastic fiber scintillator response to fast neutrons.  

PubMed

The Neutron Imaging System at NIF uses an array of plastic scintillator fibers in conjunction with a time-gated imaging system to form an image of the neutron emission from the imploded capsule. By gating on neutrons that have scattered from the 14.1 MeV DT energy to lower energy ranges, an image of the dense, cold fuel around the hotspot is also obtained. An unmoderated spallation neutron beamline at the Weapons Neutron Research facility at Los Alamos was used in conjunction with a time-gated imaging system to measure the yield of a scintillating fiber array over several energy bands ranging from 1 to 15 MeV. The results and comparison to simulation are presented. PMID:25430353

Danly, C R; Sjue, S; Wilde, C H; Merrill, F E; Haight, R C

2014-11-01

206

Plastic fiber scintillator response to fast neutrons  

NASA Astrophysics Data System (ADS)

The Neutron Imaging System at NIF uses an array of plastic scintillator fibers in conjunction with a time-gated imaging system to form an image of the neutron emission from the imploded capsule. By gating on neutrons that have scattered from the 14.1 MeV DT energy to lower energy ranges, an image of the dense, cold fuel around the hotspot is also obtained. An unmoderated spallation neutron beamline at the Weapons Neutron Research facility at Los Alamos was used in conjunction with a time-gated imaging system to measure the yield of a scintillating fiber array over several energy bands ranging from 1 to 15 MeV. The results and comparison to simulation are presented.

Danly, C. R.; Sjue, S.; Wilde, C. H.; Merrill, F. E.; Haight, R. C.

2014-11-01

207

GOOGLE EARTH QUICK GUIDE (1)Google Earth Features  

E-print Network

GOOGLE EARTH QUICK GUIDE (1)Google Earth Features The Google Earth of the Google Earth window. Often when opening up the Google Earth program, the view screen will be a view of the entire Earth from space. Navigation bar

Smith-Konter, Bridget

208

Implementation Guide  

Cancer.gov

IMPLEMENTATION GUIDE Partnership for Health Using a Research-tested Intervention Program (RTIP) to develop a process model for program delivery in the practice setting Note: Refer to “Using What Works: Adapting Evidence-Based Programs To Fit

209

Scintillating LXe\\/LKr electromagnetic calorimeter  

Microsoft Academic Search

A scintillating LXe\\/LKr electromagnetic calorimeter has been built at the ITEP and tested at the BATES (MIT) accelerator. The detector consists of PMT matrix and 45 light collecting cells made of aluminized 50 microns Mylar partially covered with p-terphenyle as a wavelength-shifter (WLS). Each pyramidal cell has (2.1×2.1)×40×(4.15×4.15) cm dimensions and is viewed by FEU-85 glass-window photomultiplier. The detector has

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

1994-01-01

210

Scintillating LXe\\/LKr electromagnetic calorimeter  

Microsoft Academic Search

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

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

1995-01-01

211

Nanophosphor composite scintillators comprising a polymer matrix  

DOEpatents

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

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

2010-11-16

212

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

213

The Oriented Scintillation Spectrometer Experiment - Instrument description  

Microsoft Academic Search

The Oriented Scintillation Spectrometer Experiment on the Arthur Holly Compton Gamma Ray Observatory satellite uses four actively shielded NaI (Tl)-CsI(Na) phoswich detectors to provide gamma-ray line and continuum detection capability in the 0.05-10 MeV energy range. The instrument includes secondary capabilities for gamma-ray and neutron detection between 10 and 250 MeV. The detectors have 3.8 deg x 11.04 deg (FWHM)

W. N. Johnson; R. L. Kinzer; J. D. Kurfess; M. S. Strickman; W. R. Purcell; D. A. Grabelsky; M. P. Ulmer; D. A. Hillis; G. V. Jung; R. A. Cameron

1993-01-01

214

Scintillation of liquid xenon and its application to nuclear radiation detectors  

Microsoft Academic Search

To understand the superiority of liquid xenon as detector medium, at first, the scintillation mechanism of liquid rare gases is explained and the absolute scintillation yield in liquid xenon is estimated and then the decay shapes of scintillation lights from liquid xenon, which are faster than those of scintillation lights from crystal scintillators recently developed, are summarized. In addition, only

T. Doke

2005-01-01

215

Scintillation of liquid xenon and its application to nuclear radiation detectors  

Microsoft Academic Search

We review the scintillation mechanism of liquid rare gases and estimate the absolute scintillation yield of liquid xenon in order to understand the superiority of liquid xenon as a detector medium. The decays of scintillation light from liquid xenon, which are faster than those of scintillation light from crystal scintillators, are summarized. New photomultipliers with high quantum efficiency that can

Tadayoshi Doke

2006-01-01

216

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

217

Health Screenings and Immunizations  

MedlinePLUS

... your primary doctor. Blood Tests – A Common Screening Method (Source: National Heart, Lung, and Blood Institute) Click ... tests, see What Are Blood Tests? Other Screening Methods Doctors can't screen for all diseases and ...

218

Screen time and children  

MedlinePLUS

"Screen time" is a term used for activities done in front of a screen, such as watching TV, working on a computer, or playing video games. Screen time is sedentary activity, meaning you are being physically ...

219

Calorimetry using organic scintillators, 'a sideways perspective'.  

SciTech Connect

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

Proudfoot, J.

1999-09-10

220

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

221

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

222

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

PubMed Central

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, factors related to obtaining Pap tests were examined using cross-sectional data from 345 Appalachian Kentucky women. Bivariate and multivariate analyses were conducted to identify predictors of screening. Results Thirty-four percent of participants were rarely- or never-screened. In multiple logistic regression analyses, several factors increased those odds, including belief that cervical cancer has symptoms, and not having a regular source of medical care. Conclusion The findings from this study may lead to the development of effective intervention and policies that increase cervical cancer screening in this population. PMID:21317514

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

2011-01-01

223

Climatology of GPS scintillations over Antarctica under solar minimum conditions  

NASA Astrophysics Data System (ADS)

We analyse GNSS ionospheric scintillation data recorded in Antarctica to investigate the conditions of the near-Earth environment leading to scintillation scenarios, producing a "scintillation climatology" over a large geomagnetic quiet period. Within this scope we realize maps of scintillation occurrence as a function of the magnetic local time (MLT) and of the altitude adjusted corrected geomagnetic coordinates (AACGM). The maps are realized merging observations of two GISTMs (GPS Ionospheric Scintillation and TEC Monitor) located at Mario Zucchelli Station (74.7°S, 164.1°E) and Concordia Station (75.1°S, 123.2°E) in Antarctica during 2008. The results highlight the possibility to investigate the impact of ionospheric irregularities on the phase and amplitude of GNSS signals, evidencing the cusp/cap and auroral contributions. This works aims to contribute to the development of nowcasting and forecasting tools for GNSS ionospheric scintillation.

Spogli, Luca; Alfonsi, Lucilla; Romano, Vincenzo; de Franceschi, Giorgiana; Mitchell, Cathryn N.

2010-05-01

224

Measurements of proportional scintillation in liquid xenon using thin wires  

E-print Network

Proportional scintillation in liquid xenon has a promising application in the field of direct dark matter detection, potentially allowing for simpler, more sensitive detectors. However, knowledge of the basic properties of the phenomenon as well as guidelines for its practical use are currently limited. We report here on measurements of proportional scintillation light emitted in liquid xenon around thin wires. The maximum proportional scintillation gain of $287^{+97}_{-75}$ photons per drift electron was obtained using 10 $\\mu$m diameter gold plated tungsten wire. The thresholds for electron multiplication and proportional scintillation are measured as $725^{+48}_{-139}$ and $412^{+10}_{-133}$ kV/cm, respectively. The threshold for proportional scintillation is in good agreement with a previously published result, while the electron multiplication threshold represents a novel measurement. A complete set of parameters for the practical use of the electron multiplication and proportional scintillation processe...

Aprile, E; Goetzke, L W; Fernandez, A J Melgarejo; Messina, M; Naganoma, J; Plante, G; Rizzo, A; Shagin, P; Wall, R

2014-01-01

225

The scintillation process in gas proportional scintillation detectors with uniform electric fields  

NASA Astrophysics Data System (ADS)

A model is developed to describe the formation of the secondary scintillation in a gas proportional scintillation detector having a uniform electric field. A simple expression is obtained for the instantaneous rate of emission of photons from the scintallator, assuming that the dominant excitation process in the gas is excitation by electron impact. The results of an experimental investigation of the photon emission from xenon following ionization of the gas by ?-particles are presented. Our observations at various gas pressures and electric intensities are shown, with the aid of the model, to be consistent with those which have been obtained by other workers using parallel plate gas proportional scintillation detectors of significantly different design and mode of operation and exposed to X-rays as well as ?-particles.

Cumpstey, D. E.; Vass, D. G.

1980-05-01

226

Application of a plastic scintillating fiber array for low-energy x-ray imaging.  

PubMed

Interest in digital imaging has led to the development of new detectors in the form of large-area displays. Most of the recent improvements are based on charge-coupled devices, a:Si photodiodes arrays, and so on. Some of these photodetectors must be coupled to scintillating screens to convert the ionizing radiation into light. Fiber-optic screens offer an advantage for achieving this interface because the length (thickness) of the interaction medium does not contribute too much to the degradation of the spatial resolution. We discuss the possibility of using a plastic scintillating fiber (PSF) array for x-ray detection and imaging in the 10-keV range. Modulation-transfer-function (MTF) measurements of the PSF array are compared with the optics MTF of the imaging system (without the sample); cross talk in the fiber array is negligible, even though the fiber array thickness is 20 mm. The optimal thickness of the array is estimated experimentally. PMID:18301701

Ikhlef, A; Skowronek, M

1998-12-01

227

Cliqbook Guides Cliqbook User Guide  

E-print Network

online. This guide provides information on: · setting up and editing your travel profile · booking flight, car rental, limo and/or hotel reservations online · finding helpful travel information Not every ....................................................................... 5 Travel Profile...................................................................6 Additional

228

Measurement of scintillation efficiency for nuclear recoils in liquid argon  

E-print Network

The scintillation light yield of liquid argon from nuclear recoils relative to electronic recoils has been measured as a function of recoil energy from 10 keVr up to 250 keVr. The scintillation efficiency, defined as the ratio of the nuclear recoil scintillation response to the electronic recoil response, is 0.25 \\pm 0.01 + 0.01(correlated) above 20 keVr.

D. Gastler; E. Kearns; A. Hime; L. C. Stonehill; S. Seibert; J. Klein; W. H. Lippincott; D. N. McKinsey; J. A. Nikkel

2012-05-08

229

Ionospheric scintillation in Brazil: Analyses and Effects on GNSS Positioning  

NASA Astrophysics Data System (ADS)

Ionosphere has a great influence on GNSS (Global Navigation Satellite System) signals and its behavior depends on several variables: local time, geographic location, seasons and solar activity. Besides, there are ionospheric irregularities that also affect the GNSS signal propagation, as the ionospheric scintillation. The ionospheric scintillation can be described as a fast change in phase and amplitude of GNSS signal, caused by irregularities of electron density. Scintillation can degrade or cause the GNSS signal lost. Due to these described factors, one can say that the ionosphere can cause important effects on GNSS positioning. It can degrade the coordinate accuracy obtained by GNSS positioning methods. In this paper the goal is to evaluate the ionospheric effect, in special the ionospheric scintillation in different regions of Brazil, and its effects on GNSS Point Positioning. In order to evaluate the days where the scintillation was more significant it is used a database (http://200.145.185.118/cigala/index.php) from CIGALA (Concept for Ionospheric Scintillation Mitigation for Professional GNSS in Latin America) project (http://cigala.galileoic.org/). Using these data it is possible to obtain information about ionospheric scintillation in different GNSS stations in Brazil. It is possible to correlate the data according to time, season and other factors that can contribute to scintillation analysis. In 2013 must occur an intense solar activity, which can intensify the ionospheric effects, and consequently ionospheric scintillation, mainly in Brazil region, where the scintillation index is already intense. Preliminary evaluations, showed larger values of S4 (scintillation index) in Brazil. For example, in October 2012, it was obtained S4 values larger than 1 in several epochs. This causes severe effects in GNSS Positioning. In this paper, the results of GNSS positioning under ionosphere scintillation effects in different regions of Brazil will be presented.

Alves, D. B.; Souza, J. S.; Silva, H. D.

2013-05-01

230

Measurement of tritium with high efficiency by using liquid scintillation counter with plastic scintillator.  

PubMed

The detection efficiencies of tritium samples by using liquid scintillation counter with hydrophilic plastic scintillator (PS) was approximately 48% when the sample of 20 ?L was held between 2 PS sheets treated by plasma. The activity and count rates showed a good relationship between 400 Bq to 410 KBq mL(-1). The calculated detection limit of 2 min measurement by the PS was 13 Bq mL(-1) when a confidence was 95%. The plasma method for PS produces no radioactive waste. PMID:24815096

Furuta, Etsuko; Ohyama, Ryu-ichiro; Yokota, Shigeaki; Nakajo, Toshiya; Yamada, Yuka; Kawano, Takao; Uda, Tatsuhiko; Watanabe, Yasuo

2014-11-01

231

Plasmonic light yield enhancement of a liquid scintillator  

SciTech Connect

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

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

2013-05-27

232

Phase and coherence of longitudinally separated equatorial ionospheric scintillation  

NASA Astrophysics Data System (ADS)

This paper presents the first calculation of phase and coherence of cross-wavelet transform applied on longitudinally separated VHF and L-band equatorial ionospheric scintillation. The cross-wavelet analysis has utilized scintillation observations made over equatorial South America and Christmas Island. Part of the results of this study has been reported recently in the Geophysical Research Letters by Shume and Mannucci (2013). The phase and coherence analysis were employed on pairs of scintillation observations separated by longitudes thereby to develop VHF and L-band scintillation (and equatorial spread F) forecast tools west of observation sites.

Shume, E. B.; Mannucci, A. J.

2013-12-01

233

Development of polystyrene-based scintillation materials and its mechanisms  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

234

Effects of geomagnetic storm on GPS ionospheric scintillations at Sanya  

NASA Astrophysics Data System (ADS)

The effects of geomagnetic storm on GPS ionospheric scintillations are studied here using GPS scintillation data recorded at Sanya (18.3°N, 109.5°E; geomagnetic: 7.6°N, 180.8°E), the southmost station in the Chinese longitude region. GPS scintillation/TEC and DMSP data are utilized to show the development of irregularities during the period year 2005 (solar minimum). Statistical analysis of K planetary index (Kp) and amplitude scintillation index (S4) indicates that most storms of the year did not trigger the scintillation occurrence at Sanya. However, cases of scintillation occurring during moderate and strong storm (Dst<-100) periods show clearly that the development of irregularities producing scintillations can be triggered by geomagnetic storms during the low scintillation occurrence season. The effects (trigger or not trigger/inhibit) depend on the maximum dDst/dt determined local time sector, and can be explained by the response of the equatorial vertical drift velocities to magnetospheric and ionospheric disturbance electric fields. For station Sanya, the maximum dDst/dt determined local time is near the noon (or post-midnight) sector for most storms of the year 2005, which inhibited (or did not trigger) the post-sunset (or post-midnight) scintillation occurrence and then led to the phenomena that the statistical results presented.

Li, Guozhu; Ning, Baiqi; Zhao, Biqiang; Liu, Libo; Liu, J. Y.; Yumoto, K.

2008-05-01

235

Liquid-helium scintillation detection with germanium photodiodes  

SciTech Connect

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

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

1982-05-01

236

GPS phase scintillation and proxy index at high latitudes during a moderate geomagnetic storm  

E-print Network

The amplitude and phase scintillation indices are customarily obtained by specialised GPS Ionospheric Scintillation and TEC Monitors (GISTMs) from L1 signal recorded at the rate of 50 Hz. The scintillation indices S[subscript ...

Prikryl, P.

237

Data Quality Screening Service  

NASA Technical Reports Server (NTRS)

A report describes the Data Quality Screening Service (DQSS), which is designed to help automate the filtering of remote sensing data on behalf of science users. Whereas this process often involves much research through quality documents followed by laborious coding, the DQSS is a Web Service that provides data users with data pre-filtered to their particular criteria, while at the same time guiding the user with filtering recommendations of the cognizant data experts. The DQSS design is based on a formal semantic Web ontology that describes data fields and the quality fields for applying quality control within a data product. The accompanying code base handles several remote sensing datasets and quality control schemes for data products stored in Hierarchical Data Format (HDF), a common format for NASA remote sensing data. Together, the ontology and code support a variety of quality control schemes through the implementation of the Boolean expression with simple, reusable conditional expressions as operands. Additional datasets are added to the DQSS simply by registering instances in the ontology if they follow a quality scheme that is already modeled in the ontology. New quality schemes are added by extending the ontology and adding code for each new scheme.

Strub, Richard; Lynnes, Christopher; Hearty, Thomas; Won, Young-In; Fox, Peter; Zednik, Stephan

2013-01-01

238

Art Guide  

NSDL National Science Digital Library

Developed by Cognitive Applications Limited, Art Guide is a comprehensive guide to the art collections of Great Britain and Ireland. The site is divided into three main sections, allowing users to browse for exhibits by artist, museum, or geographic location. The Art Guide database currently contains over 1,900 artists, more than 650 museums, and over 4,500 individual listings. Each artist listing features a list of works on display and their location; each museum listing describes the highlights of its collection, and provides an address and phone number, a link to its website (where available) and links to other museums in that region. Additional site features include a separate listing of museums with web sites and kid-friendly destinations, a comprehensive exhibition listing, and a visitors discussion forum.

239

Cervical Cancer Screening  

MedlinePLUS

What is cervical cancer screening? Cervical cancer screening is used to find changes in the cells of the cervix that could lead to ... the FAQ Human Papillomavirus [HPV] Infection). How is cervical cancer screening done? Cervical cancer screening is simple and fast. ...

240

Breast Cancer Screening  

MedlinePLUS

... ongoing clinical trials is available from the NCI Web site . Three tests are used by health care providers to screen ... ongoing clinical trials is available from the NCI Web site . Risks of Breast Cancer Screening Screening tests have risks. Decisions about screening tests can be ...

241

Destination Guide  

NSDL National Science Digital Library

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

242

Medicare Preventive and Screening Services  

MedlinePLUS

... management training Glaucoma tests HIV screening Mammograms (screening) Nutrition therapy services Obesity screenings & counseling One-time “Welcome to Medicare” preventive visit Prostate cancer screenings Sexually transmitted infections screening & counseling Shots: Flu ...

243

Plasma Screen Floating Mount  

DOEpatents

A mounting system for a flat display screen, particularly a plasma display screen, suspends the screen separately in each of the x-, y- and z-directions. A series of frames located by linear bearings and isolated by springs and dampers allows separate controlled movement in each axis. The system enables the use of relatively larger display screens in vehicles in which plasma screen are subject to damage from vibration.

Eakle, Robert F. (New Ellenton, SC); Pak, Donald J. (Martine, GA)

2004-10-26

244

Emergency Guide Tuscarawas Campus  

E-print Network

.................................................................................7 Biological Threat........................................................................... 11Emergency Guide Tuscarawas Campus Kent State University Prepared by: Kent State University Police;Emergency Guide Using the Emergency Guide The Tuscarawas Campus Emergency Guide is a companion document

Khan, Javed I.

245

Scintillating ribbon x-ray detector  

SciTech Connect

A patent in the early 1970`s by Aerojet Corporation in Sacramento, CA put forth the idea of using an array of scintillating fibers for x-ray detection and imaging. In about 1975, Pratt and Whitney Aircraft in East Hartford, CT designed and manufactured an imaging system based on the patent. The device was 1.75 in thick in the direction of the x-ray beam and about 4 in. by 4 in. square. The device was used with a 8 MeV x-ray source to image and measure internal clearances within operating aircraft, gas turbines engines. There are significant advantages of fiber optic detectors in x-ray detection. However, the advantages are often outweighed by the disadvantages. Two of the advantages of scintillating fiber optic x-ray detectors are: (1) high limiting spatial frequency -- between 20 and 25 lp/mm; and (2) excellent x-ray stopping power -- they can be made thick and retain spatial resolution. In traditional fiber optic detectors the x-rays are oriented parallel to the long axis of the fiber. For the scintillating ribbon x-ray sensor, the x-rays are oriented normal to the fiber long axis. This ribbon sensor technique has a number of advantages over the two current radiographic techniques digital x-radiography and x-ray film: The main advantage the ribbon has is size and shape. It can be as thin as 0.05 in., virtually any width or length, and flexible. Once positioned in a given location, 20 to 100 square inches of the object being inspected can be imaged with a single x-ray beam sweep. It is clear that conventional digital cameras do not lend themselves to placement between walls of aircraft structures or similar items requiring x-ray inspections. A prototype scintillating ribbon x-ray sensor has been fabricated and tested by Synergistic Detector Designs. Images were acquired on corrosion test panels of aluminum fabricated by Iowa State University.

Kinchen, B.E. [BK Science and Engineering, Fremont, CA (United States); Rogers, A. [Synergistic Detector Designs, Sunnyvale, CA (United States)

1995-12-31

246

Fundamental limits of scintillation detector timing precision.  

PubMed

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

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

2014-07-01

247

Measurement of Scintillation and Ionization Yield and Scintillation Pulse Shape from Nuclear Recoils in Liquid Argon  

E-print Network

We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase Liquid Argon Time Projection Chamber (LAr-TPC) to a low energy pulsed narrowband neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.2 keV and for applied electric fields from 0 to 1000 V/cm. For the ionization yields, we report measurements from 16.9 to 57.2 keV and for electric fields from 50 to 500 V/cm. We also report the observation of an anti-correlation between scintillation and ionization from nuclear recoils, which is similar to the anti-correlation between scintillation and ionization from electron recoils. Assuming that the energy partition in excitons and ion pairs of $^{83m}$Kr internal conversion electrons is comparable to that of $^{207}$Bi conversion electrons, we obtained the numbers of excitons ($N_{\\rm ex}$) and ion pairs ($N_{\\rm i}$) and their ratio ($N_{\\rm ex}$/$N_{\\rm i}$) produced by nuclear recoils from 16.9 to 57.2 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.

H. Cao; T. Alexander; A. Aprahamian; R. Avetisyan; H. O. Back; A. G. Cocco; F. DeJongh; G. Fiorillo; C. Galbiati; L. Grandi; Y. Guardincerri; C. Kendziora; W. H. Lippincott; C. Love; S. Lyons; L. Manenti; C. J. Martoff; Y. Meng; D. Montanari; P. Mosteiro; D. Olvitt; S. Pordes; H. Qian; B. Rossi; R. Saldanha; S. Sangiorgio; K. Siegl; S. Y. Strauss; W. Tan; J. Tatarowicz; S. Walker; H. Wang; A. W. Watson; S. Westerdale; J. Yoo

2014-07-16

248

VIP How-to Guide Personal Section  

E-print Network

. You will be able to list your top choices for on- campus housing, search for and select a roommate to the next page. #12;VIP How-to Guide 3 8 - Your name and address will be entered on this screen based the "Next" button to proceed. 9 - You are required to enter at least one Emergency Contact. You can also

Almor, Amit

249

A Guide to Audiovisual Resources about ERIC.  

ERIC Educational Resources Information Center

The currently available audiovisual products about ERIC reviewed in this guide have been developed to meet the needs of a variety of users with varying familiarity with the system. Materials to be included were screened on the basis of availability, currency, and technical quality. The remaining products were then reviewed using five criteria: (1)…

Ely, Donald P.

250

Optimization of the performance of segmented scintillators for radiotherapy imaging through novel binning techniques.  

PubMed

Thick, segmented crystalline scintillators have shown increasing promise as replacement x-ray converters for the phosphor screens currently used in active matrix flat-panel imagers (AMFPIs) in radiotherapy, by virtue of providing over an order of magnitude improvement in the detective quantum efficiency (DQE). However, element-to-element misalignment in current segmented scintillator prototypes creates a challenge for optimal registration with underlying AMFPI arrays, resulting in degradation of spatial resolution. To overcome this challenge, a methodology involving the use of a relatively high resolution AMFPI array in combination with novel binning techniques is presented. The array, which has a pixel pitch of 0.127 mm, was coupled to prototype segmented scintillators based on BGO, LYSO and CsI:Tl materials, each having a nominal element-to-element pitch of 1.016 mm and thickness of ? 1 cm. The AMFPI systems incorporating these prototypes were characterized at a radiotherapy energy of 6 MV in terms of modulation transfer function, noise power spectrum, DQE, and reconstructed images of a resolution phantom acquired using a cone-beam CT geometry. For each prototype, the application of 8 × 8 pixel binning to achieve a sampling pitch of 1.016 mm was optimized through use of an alignment metric which minimized misregistration and thereby improved spatial resolution. In addition, the application of alternative binning techniques that exclude the collection of signal near septal walls resulted in further significant improvement in spatial resolution for the BGO and LYSO prototypes, though not for the CsI:Tl prototype due to the large amount of optical cross-talk resulting from significant light spread between scintillator elements in that device. The efficacy of these techniques for improving spatial resolution appears to be enhanced for scintillator materials that exhibit mechanical hardness, high density and high refractive index, such as BGO. Moreover, materials that exhibit these properties as well as offer significantly higher light output than BGO, such as CdWO4, should provide the additional benefit of preserving DQE performance. PMID:24487347

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

2014-02-21

251

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

252

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

253

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.

254

Reflection Guides  

NSDL National Science Digital Library

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

2012-01-01

255

Polymers Guide  

NSDL National Science Digital Library

This 21 page document contains an instructor guide for the polymers module from Nano-Link. The activity requires a background in eight grade science. The document includes background information on polymers, a hands-on learning activity, questions to check understanding, links to multimedia resources, and further readings. Visitors must complete a quick and free registration to access the materials.

256

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...

257

Semiconductor scintillator based on photon recycling Serge Luryi n  

E-print Network

Semiconductor scintillator based on photon recycling Serge Luryi n , Arsen V. Subashiev University efficiency a b s t r a c t Direct-bandgap semiconductor with high quantum radiative efficiency can operate of photoreceivers on both sides of the semiconductor scintillator wafer is desirable. & 2011 Elsevier B.V. All

Luryi, Serge

258

Avalanche Photodiode for liquid xenon scintillation: quantum efficiency and gain  

Microsoft Academic Search

We report on measurements with a large area, silicon Avalanche Photodiode (APD) as photodetector for the ultraviolet scintillation light of liquid xenon (LXe) at temperatures between 167 and 188 K. The maximum gain of the APD for the scintillation light from a 210Po alpha-source in LXe was 5.3 × 103. Based on the geometry of the setup, the quantum efficiency

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

2009-01-01

259

Purification of KamLAND-Zen liquid scintillator  

SciTech Connect

KamLAND-Zen is neutrino-less double-beta decay search experiment using enriched 300 kg of {sup 136}Xe dissolved in pure liquid scintillator. This report is purification work of liquid scintillator for KamLAND-Zen experiment before installation in the inner-balloon and background rejection processes after installation.

Ikeda, Haruo [Research Center for Neutrino Science, Tohoku University, Sendai 980-8578 (Japan)] [Research Center for Neutrino Science, Tohoku University, Sendai 980-8578 (Japan)

2013-08-08

260

Ionospheric scintillation effects on VHF-UHF communication systems  

Microsoft Academic Search

Periods of intense ionospheric scintillations were analyzed in order to provide information for the design and evaluation of the performance of satellite communication links. Scintillation data were available for the auroral and equatorial regions. The amplitude fluctuations are described by cumulative amplitude distributions and show good agreement with the Nakagami m-distribution. A Rayleigh distribution appears to describe the worst case

H. E. Whitney

1976-01-01

261

Time and position distributions in large volume spherical scintillation detectors  

Microsoft Academic Search

Large spherical scintillation detectors are playing an increasingly important role in experimental neutrino physics studies. From the instrumental point of view, the primary signal response of these set-ups is constituted by the time and amplitude of the anode pulses delivered by each individual phototube following a particle interaction in the scintillator. In this work, under some approximate assumptions, we derive

Paolo Lombardi; Gioacchino Ranucci

2007-01-01

262

Restoration of continuous turbulence profile from lunar scintillation A. Tokovinin  

E-print Network

Restoration of continuous turbulence profile from lunar scintillation A. Tokovinin Version 1.1. June 11, 2008 [prj/atm/moon/doc/restor3.tex] 1 Introduction Optical turbulence near the ground can be measured by a suitable analysis of lunar or solar scintillation. However, the problem of restoring

Tokovinin, Andrei A.

263

Statistics of ionospheric scintillation occurrence over European high latitudes  

NASA Astrophysics Data System (ADS)

Rapid fluctuation in the amplitude and phase of transionospheric radio signals caused by small scale ionospheric plasma density irregularities is known as scintillation. Over the high latitudes, irregularities causing scintillation are associated with large scale plasma structures and scintillation occurrence is mainly enhanced during geomagnetic storms. This paper presents a statistical analysis of scintillation occurrence on GPS L1C/A signal at a high latitude station located in Bronnoysund (geographic latitude 65.5°N, geographic longitude 12.2°E; corrected geomagnetic (CGM) latitude 62.77°N), Norway, during the periods around the peaks of solar cycles 23 (2002-2003) and 24 (2011-2013). The analysis revealed that the scintillation occurrence at Bronnoysund during both the solar maximum periods maximises close to the midnight magnetic local time (MLT) sector. A higher occurrence of scintillation is observed on geomagnetically active days during both the solar maximum periods. The seasonal pattern of scintillation occurrence indicated peaks during the summer and equinoctial months. A comparison with the interplanetary magnetic field (IMF) components By and Bz showed an association of scintillation occurrence with the southward IMF Bz conditions.

Sreeja, V.; Aquino, M.

2014-12-01

264

Recent observations of equatorial and high latitude scintillations  

Microsoft Academic Search

At equatorial latitudes, combined airborne and ground measurements of radar backscatter, electron density profiles, scintillations, airglow at 6300 A, and total electron content yielded data on the development and decay of the irregularity patches containing the hundred meter irregularities responsible for amplitude and phase scintillation. The use of airglow measurements from aircraft allowed the form of the patch to be

J. Aarons; H. E. Whitney

1980-01-01

265

TOF-PET detector concept based on organic scintillators  

E-print Network

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

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

2013-01-01

266

Microprocessor-based single particle calibration of scintillation counter  

NASA Astrophysics Data System (ADS)

A microprocessor-base set-up is fabricated and tested for the single particle calibration of the plastic scintillator. The single particle response of the scintillator is digitized by an A/D converter, and a 8085 A based microprocessor stores the pulse heights. The digitized information is printed. Facilities for CRT display and cassette storing and recalling are also made available.

Mazumdar, G. K. D.; Pathak, K. M.

1985-08-01

267

A Scintillating Fibre Tracker for the LHCb Upgrade  

NASA Astrophysics Data System (ADS)

A scintillating fibre tracker with multichannel silicon photomultiplier readout is an option for the LHCb upgrade. The radiation hardness of the scintillating fibres and silicon photomultipliers has been studied. Production methods and machines to build 5m long modules with an accuracy of 50 ?m have been designed and built. All developments are well on track for the technical design report in March 2014.

Ekelhof, Robert

2014-06-01

268

Scintillation of electromagnetic beams generated by quasi-homogeneous sources  

NASA Astrophysics Data System (ADS)

We derive an expression for the far-zone scintillation index of electromagnetic beams that are generated by quasi-homogeneous sources. By examining different types of sources, we find conditions under which this index reaches its minimum or its maximum value. It is demonstrated that under certain circumstances two sources with different spectral densities can produce beams with identical scintillation indices.

Friberg, Ari T.; Visser, Taco D.

2015-01-01

269

Measurement of ortho-positronium properties in liquid scintillators  

NASA Astrophysics Data System (ADS)

Pulse shape discrimination in liquid scintillator detectors is a well-established technique for the discrimination of heavy particles from light particles. Nonetheless, it is not efficient in the separation of electrons and positrons, as they give rise to indistinguishable scintillator responses. This inefficiency can be overtaken through the exploitation of the formation of ortho-Positronium (o-Ps), which alters the time profile of light pulses induced by positrons. We characterized the o-Ps properties in the most commonly used liquid scintillators, i.e. PC, PXE, LAB, OIL and PC + PPO. In addition, we studied the effects of scintillator doping on the o-Ps properties for dopants currently used in neutrino experiments, Gd and Nd. Further measurements for Li-loaded and Tl-loaded liquid scintillators are foreseen. We found that the o-Ps properties are suitable for enhancing the electron-positron discrimination.

Perasso, S.; Consolati, G.; Franco, D.; Hans, S.; Jollet, C.; Meregaglia, A.; Tonazzo, A.; Yeh, M.

2013-08-01

270

Measurement of ortho-Positronium Properties in Liquid Scintillators  

E-print Network

Pulse shape discrimination in liquid scintillator detectors is a well-established technique for the discrimination of heavy particles from light particles. Nonetheless, it is not efficient in the separation of electrons and positrons, as they give rise to indistinguishable scintillator responses. This inefficiency can be overtaken through the exploitation of the formation of ortho-Positronium (o-Ps), which alters the time profile of light pulses induced by positrons. We characterized the o-Ps properties in the most commonly used liquid scintillators, i.e. PC, PXE, LAB, OIL and PC + PPO. In addition, we studied the effects of scintillator doping on the o-Ps properties for dopants currently used in neutrino experiments, Gd and Nd. Further measurements for Li-loaded and Tl-loaded liquid scintillators are foreseen. We found that the o-Ps properties are suitable for enhancing the electron-positron discrimination.

S. Perasso; G. Consolati; D. Franco; S. Hans; C. Jollet; A. Meregaglia; A. Tonazzo; M. Yeh

2013-06-25

271

Measurement of ortho-Positronium Properties in Liquid Scintillators  

E-print Network

Pulse shape discrimination in liquid scintillator detectors is a well-established technique for the discrimination of heavy particles from light particles. Nonetheless, it is not efficient in the separation of electrons and positrons, as they give rise to indistinguishable scintillator responses. This inefficiency can be overtaken through the exploitation of the formation of ortho-Positronium (o-Ps), which alters the time profile of light pulses induced by positrons. We characterized the o-Ps properties in the most commonly used liquid scintillators, i.e. PC, PXE, LAB, OIL and PC + PPO. In addition, we studied the effects of scintillator doping on the o-Ps properties for dopants currently used in neutrino experiments, Gd and Nd. Further measurements for Li-loaded and Tl-loaded liquid scintillators are foreseen. We found that the o-Ps properties are suitable for enhancing the electron-positron discrimination.

Perasso, S; Franco, D; Hans, S; Jollet, C; Meregaglia, A; Tonazzo, A; Yeh, M

2013-01-01

272

Optimization of light collection from crystal scintillators for cryogenic experiments  

E-print Network

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

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

2014-02-10

273

Kinetic Monte Carlo simulations of scintillation processes in NaI(Tl)  

SciTech Connect

Developing a comprehensive understanding of the processes that govern the scintillation behavior of inorganic scintillators provides a pathway to optimize current scintillators and allows for the science-driven search for new scintillator materials. Recent experimental data on the excitation density dependence of the light yield of inorganic scintillators presents an opportunity to incorporate parameterized interactions between excitations in scintillation models and thus enable more realistic simulations of the nonproportionality of inorganic scintillators. Therefore, a kinetic Monte Carlo (KMC) model of elementary scintillation processes in NaI(Tl) is developed in this work to simulate the kinetics of scintillation for a range of temperatures and Tl concentrations as well as the scintillation efficiency as a function of excitation density. The ability of the KMC model to reproduce available experimental data allows for elucidating the elementary processes that give rise to the kinetics and efficiency of scintillation observed experimentally for a range of conditions.

Kerisit, Sebastien N.; Wang, Zhiguo; Williams, Richard; Grim, Joel; Gao, Fei

2014-04-26

274

[Lung cancer screening].  

PubMed

Lung cancer is a very important disease, curable in early stages. There have been trials trying to show the utility of chest x-ray or computed tomography in Lung Cancer Screening for decades. In 2011, National Lung Screening Trial results were published, showing a 20% reduction in lung cancer mortality in patients with low dose computed tomography screened for three years. These results are very promising and several scientific societies have included lung cancer screening in their guidelines. Nevertheless we have to be aware of lung cancer screening risks, such as: overdiagnosis, radiation and false positive results. Moreover, there are many issues to be solved, including choosing the appropriate group to be screened, the duration of the screening program, intervals between screening and its cost-effectiveness. Ongoing trials will probably answer some of these questions. This article reviews the current evidence on lung cancer screening. PMID:23830728

Sánchez González, M

2014-01-01

275

Liquid scintillation detectors for high energy neutrinos  

NASA Astrophysics Data System (ADS)

Large liquid scintillation detectors have been generally used for low energy neutrino measurements, in the MeV energy region. We describe the potential employment of large detectors (>1 kiloton) for studies of higher energy neutrino interactions, such as cosmic rays and long baseline experiments. When considering the physics potential of new large instruments the possibility of doing useful measurements with higher energy neutrino interactions has been overlooked. Here we take into account Fermat’s principle, which states that the first light to reach each PMT will follow the shortest path between that PMT and the point of origin. We describe the geometry of this process, and the resulting wavefront, which we call the “Fermat surface”, and discuss methods of using this surface to extract directional track information and particle identification. This capability may be demonstrated in the new long baseline neutrino beam from Jaeri accelerator to the KamLAND detector in Japan. Other exciting applications include the use of Hanohano as a movable long baseline detector in this same beam, and LENA in Europe for future long baseline neutrino beams from CERN. Also, this methodology opens up the question as to whether a large liquid scintillator detector should be given consideration for use in a future long baseline experiment from Fermilab to the DUSEL underground laboratory at Homestake.

Smith, Stefanie N.; Learned, John G.

2010-04-01

276

Liquid Scintillation Detectors for High Energy Neutrinos  

SciTech Connect

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

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

2010-03-30

277

Liquid Scintillation Detectors for High Energy Neutrinos  

NASA Astrophysics Data System (ADS)

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

Smith, Stefanie N.; Learned, John G.

2010-03-01

278

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

279

SDC conceptual design: Scintillating fiber outer tracker  

SciTech Connect

The authors propose an all-scintillating fiber detector for the purpose of outer tracking for the SDC. The objectives of this tracking system are to: (1) provide a first level trigger for {vert_bar}{eta}{vert_bar} < 2.3 with sharp p{sub T} threshold with the ability to resolve individual beam crossings; (2) provide pattern recognition capability and momentum resolution which complements and extends the capabilities of the inner silicon tracking system; (3) provide three dimensional linkage with outer detection systems including the shower maximum detector, muon detectors, and calorimetry; (4) provide robust tracking and track-triggering at the highest luminosities expected at the SSC. The many attractive features of a fiber tracker include good position resolution, low occupancy, low mass in the active volume, and excellent resistance to radiation damage. An additional important feature, especially at the SSC, is the intrinsically prompt response time of a scintillating fiber. This property is exploited in the construction of a level 1 trigger sensitive to individual beam crossings.

Adams, D. [Rice Univ., Houston, TX (United States); Baumbaugh, A. [Fermi National Accelerator Lab., Batavia, IL (United States); Bird, F. [ed.] [Superconducting Super Collider Lab., TX (United States)] [and others; SDC Collaboration

1992-01-22

280

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

281

A Job Seeker's Guide About this Guide  

E-print Network

. Included in this guide are many helpful tips that you can use throughout your job search process letters. These websites can be accessed by using a search engine such as www.google.com. Key words to useA Job Seeker's Guide About this Guide This guide is designed to assist you in your job search

Butler, Laurie J.

282

Oral Cancer Screening  

MedlinePLUS

... available from the NCI Web site . There is no standard or routine screening test for oral cancer. ... other areas by the time they are found. No studies have shown that screening would decrease the ...

283

Screening for Gestational Diabetes  

MedlinePLUS

... Grade B), it is because it has more potential benefits than potential harms. When there is not enough evidence to ... information on screening in this population to determine potential benefits and harms. 1 2 Getting Screened for ...

284

Breast Cancer Screening  

MedlinePLUS Videos and Cool Tools

... the lower right-hand corner of the player. Breast Cancer Screening HealthDay December 3, 2014 Related MedlinePlus Pages Breast Cancer Mammography Women's Health Transcript Mammography screening strategies based ...

285

Screening for Birth Defects  

MedlinePLUS

... extra chromosome. A common trisomy is trisomy 21 (Down syndrome) . Other trisomies include trisomy 13 (Patau syndrome) and ... Test Test Type What Does It Screen for? Down Syndrome Detection Rate Combined firsttrimester screening Blood test for ...

286

National Lung Screening Trial  

Cancer.gov

Information about the National Lung Screening Trial (NLST), a research study sponsored by the National Cancer Institute that used low-dose helical CT scans or chest X-ray to screen men and women at risk for lung cancer.

287

Periodic Screening Evaluation  

Cancer.gov

Statistical Software Periodic Screening Evaluation (Written by Stuart G. Baker) New Approach (Simplified Approximation): See Baker SG. Evaluating periodic cancer screening without a randomized control group: a simplified design and analysis. In: Duffy

288

Screening for Cervical Cancer  

MedlinePLUS

... in women age 21 to 65 years with cytology (Pap smear) every 3 years or, for women ... the screening interval, screening with a combination of cytology and human papillomavirus (HPV) testing every 5 years. ...

289

Video Screen Capture Basics  

ERIC Educational Resources Information Center

This article is an introduction to video screen capture. Basic information of two software programs, QuickTime for Mac and BlueBerry Flashback Express for PC, are also discussed. Practical applications for video screen capture are given.

Dunbar, Laura

2014-01-01

290

Cervical Cancer Screening  

MedlinePLUS

... Cancer found early may be easier to treat. Cervical cancer screening is usually part of a woman's health ... may do more tests, such as a biopsy. Cervical cancer screening has risks. The results can sometimes be ...

291

International Cancer Screening Network  

Cancer.gov

Skip to Main Content Search International Cancer Screening Network Sponsored by the National Cancer Institute Working Together to Evaluate Cancer Screening and Improve Outcomes Internationally About the ICSN Overview Participating Countries Contact

292

Quasiperiodic scintillation and data interpretation: Nongeophysical GPS amplitude fluctuations due to intersatellite interference  

NASA Astrophysics Data System (ADS)

Spectrograms of high-rate Global Positioning System (GPS) power data at the L1 frequency (1.57542 GHz) commonly show patterns of fluctuation frequency with respect to time that resemble quasiperiodic scintillation observations. These fluctuation patterns have probably not been noted in the past because of the low sampling frequencies and coarse quantization of power measurements in most GPS receivers. We demonstrate that the source of these fluctuations is usually not edge-type diffraction from steep ionospheric gradients, as is often hypothesized for quasiperiodic scintillation, despite some features consistent with ionospheric generation. Instead, in most cases these spectrogram patterns derive from intersatellite signal interference between pairs of coarse/acquisition (C/A) codes broadcast on L1. As evidence of this mechanism, we show that most spectrogram features appear on pairs of satellite tracking channels and that the patterns can be reproduced using a multisatellite GPS simulator. We also model the spectrogram patterns, both with regard to the basic GPS C/A code correlation process and the differential Doppler shift conditions that cause the fluctuations. In this latter respect, the GPS quasiperiodic scintillation observations bear resemblance to a mechanism discussed by L. A. Hajkowicz for traditional satellite beacons. Despite the complex nature of the intersatellite interference phenomenon, we can model when the spectrogram patterns are expected to appear. Thus one can screen out these time-varying interference patterns to find potential occurrences of actual ionospheric edge diffraction in spectrograms. The intersatellite interference phenomenon is also of general interest to GPS radio engineering.

Beach, Theodore L.; Baragona, Curtis A.

2007-06-01

293

Higher order moments used in ionospheric scintillation description  

NASA Astrophysics Data System (ADS)

Ionospheric scintillations, caused by small scale fluctuations in the electron density structure, presents one of the most influential factor in transionospheric radio wave propagation and important topic for the mitigation of its effects. Initiating disturbances and distortion in phase and amplitude of the propagating signal, scintillation can significantly affect the GNSS accuracy and cause serious problems to commercial navigation systems. Decades of investigations of the probability distribution of the scintillating signals brought a lot of possible solutions, several of them are widely adopted and are in use this days. Solutions like joint Gaussian distribution of complex signal and Rytov solution seems to work for weak scintillating signals, but still there is not an easy way to derive satisfactory results, leading to need for further investigations [Yeh and Liu, 1982]. The focus of this paper is on the statistical analysis of ionospheric scintillation. We analyze various probability distribution functions of scintillating signals using simulated and real data. The analysis results are presented through higher order moments, dependent on various parameters (scintillation index, phase variance, season, time of the day and solar/magnetic activity). Implementation of higher order moments, skewness and kurtosis, could give more information about the ionospheric irregularities influence on the propagating signal and relation to the time delay of the signal.

Stevanovic, D.; Wernik, A. W.

2013-12-01

294

Electronic Structure Engineering of Elpasolites for Brighter and Faster Scintillators  

NASA Astrophysics Data System (ADS)

Utilization of scintillator materials is one of the primary methods for radiation detection. Elpasolites are a large family of quaternary halides that have attracted considerable interest for their potential applications as ?-ray and neutron scintillators. However, many elpasolite scintillator materials currently under development suffer from low light yield and long scintillation decay time. The low light yield is partially due to a large band gap while the long scintillation decay time is a result of slow carrier transport to Ce dopants, where electrons and holes recombine to emit photons. We suggest that these problems may be mitigated by optimizing the band gap and carrier mobility by selecting constituent elements of proper electronegativity. For example, cations with lower electronegativity may lower the conduction band and increase the conduction band dispersion simultaneously, resulting in higher light yield and faster scintillation. First-principles calculations of electronic structure, small polarons, and Ce dopants in Cs2LiYCl6 and Cs2AgYCl6 compounds show that the strategy of manipulating electronegativity can lead to brighter and faster elpasolite-based scintillators. This work was supported by the U.S. DOE Office of Nonproliferation Research and Development NA22.

Du, Mao-Hua; Biswas, Koushik

2013-03-01

295

Cost-effective segmented scintillating converters for hard x rays  

NASA Astrophysics Data System (ADS)

Thick segmented scintillating converters coupled to optical imaging detectors offer the advantage of large area, high stopping power sensors for high energy x-ray digital imaging. The recent advent of high resolution and solid state optical sensors such as amorphous silicon arrays and CCD optical imaging detectors makes it feasible to build large, cost effective imaging arrays. This technology, however, shifts the sensor cost burden to the segmented scintillators needed for imaging. The required labor intensive fabrication of high resolution, large area hard x- ray converters results in high cost and questionable manufacturability on a large scale. We report on recent research of a new segmented x-ray imaging converter. This converter is fabricated using vacuum injection and crystal growth methods to induce defect free, high density scintillating fibers into a collimator matrix. This method has the potential to fabricate large area, thick segmented scintillators. Spatial resolution calculations of these scintillator injected collimators show that the optical light spreading is significantly reduced compared to single crystalline scintillators and sub-millimeter resolution x- ray images acquired with the segmented converter coupled to a cooled CCD camera provided the resolution to characterize the converter efficiency and noise. The proposed concept overcomes the above mentioned limitations by producing a cost-effective technique of fabricating large area x-ray scintillator converters with high stopping power and high spatial resolution. This technology will readily benefit diverse fields such as particle physics, astronomy, medicine, as well as industrial nuclear and non-destructive testing.

Vasile, Stefan A.; Gordon, Jeffrey S.; Klugerman, Mikhail; Nagarkar, Vivek V.; Squillante, Michael R.; Entine, Gerald; Watson, Scott; Kauppila, Todd J.

1996-07-01

296

Statistical study of UHF scintillations conducted between 1994 and 2013  

NASA Astrophysics Data System (ADS)

A spaced-antenna scintillation system was installed at Ancon, Peru in May 1994 to measure amplitude fluctuations of 250-MHz signals from a geostationary satellite located 100° W using three antennas spaced in the magnetic east-west direction. The system also included a receiver of L-band signals from the GOES satellite and a second baseline was added in November 1996 consisting of 2 spaced-antennas receiving UHF signals from a satellite at 25° W. This system also called the MISETA scintillation system was designed and built under supervision of Dr. Santimay Basu. The MISETA measurements have provided the climatology of amplitude scintillation and zonal irregularity drifts during almost 2 solar cycles. In addition to these statistical results, The MISETA system has been used to study in detail scintillation onset, duration, recurrence, and S4 intensity during special atmospheric processes such as stratospheric sudden warming (SSW) events. It was found that during SSW events scintillations occurred less frequently and appeared at later local times. Our conclusions are also compared with measurements from other scintillation/equatorial spread F sensors that exist in the Peruvian region. Digisonde and VIPIR ionosondes, coherent radars, imagers, and GPS receivers from the LISN network in South America, provide additional information on the characteristics of the disturbed environment and endorse the UHF scintillation results.

Valladares, C. E.; Sheehan, R. E.

2013-12-01

297

Screening for Lung Cancer  

PubMed Central

Background: Lung cancer is by far the major cause of cancer deaths largely because in the majority of patients it is at an advanced stage at the time it is discovered, when curative treatment is no longer feasible. This article examines the data regarding the ability of screening to decrease the number of lung cancer deaths. Methods: A systematic review was conducted of controlled studies that address the effectiveness of methods of screening for lung cancer. Results: Several large randomized controlled trials (RCTs), including a recent one, have demonstrated that screening for lung cancer using a chest radiograph does not reduce the number of deaths from lung cancer. One large RCT involving low-dose CT (LDCT) screening demonstrated a significant reduction in lung cancer deaths, with few harms to individuals at elevated risk when done in the context of a structured program of selection, screening, evaluation, and management of the relatively high number of benign abnormalities. Whether other RCTs involving LDCT screening are consistent is unclear because data are limited or not yet mature. Conclusions: Screening is a complex interplay of selection (a population with sufficient risk and few serious comorbidities), the value of the screening test, the interval between screening tests, the availability of effective treatment, the risk of complications or harms as a result of screening, and the degree with which the screened individuals comply with screening and treatment recommendations. Screening with LDCT of appropriate individuals in the context of a structured process is associated with a significant reduction in the number of lung cancer deaths in the screened population. Given the complex interplay of factors inherent in screening, many questions remain on how to effectively implement screening on a broader scale. PMID:23649455

Mazzone, Peter J.; Naidich, David P.; Bach, Peter B.

2013-01-01

298

Gene Expression Changes in Developing Zebrafish as Potential Markers for Rapid Developmental Neurotoxicity Screening  

EPA Science Inventory

Sparse information exists on many chemicals to guide developmental neurotoxicity (DNT) risk assessments. As DNT testing using rodents is laborious and expensive, alternative species such as zebrafish are being adapted for toxicity screening. Assessing the DNT potential of chem...

299

Lanthanum halide scintillators for time-of-flight 3-D pet  

DOEpatents

A Lanthanum Halide scintillator (for example LaCl.sub.3 and LaBr.sub.3) with fast decay time and good timing resolution, as well as high light output and good energy resolution, is used in the design of a PET scanner. The PET scanner includes a cavity for accepting a patient and a plurality of PET detector modules arranged in an approximately cylindrical configuration about the cavity. Each PET detector includes a Lanthanum Halide scintillator having a plurality of Lanthanum Halide crystals, a light guide, and a plurality of photomultiplier tubes arranged respectively peripherally around the cavity. The good timing resolution enables a time-of-flight (TOF) PET scanner to be developed that exhibits a reduction in noise propagation during image reconstruction and a gain in the signal-to-noise ratio. Such a PET scanner includes a time stamp circuit that records the time of receipt of gamma rays by respective PET detectors and provides timing data outputs that are provided to a processor that, in turn, calculates time-of-flight (TOF) of gamma rays through a patient in the cavity and uses the TOF of gamma rays in the reconstruction of images of the patient.

Karp, Joel S. (Glenside, PA); Surti, Suleman (Philadelphia, PA)

2008-06-03

300

Development of scintillating fiber detector technology for high rate particle tracking  

E-print Network

The performance of a scintillating fiber detector prototype for tracking under high rate conditions is investigated. A spatial resolution of about100 micron is aimed for the detector. Further demands are low occupancy and radiation hardness up to 1 Mrad/year. Fibers with different radii and different wavelengths of the scintillation light from different producers have been extensively tested concerning light output, attenuation length and radiation hardness, with and without coupling them to light guides of different length and diameter. In a testrun at a 3 GeV electron beam the space dependent efficiency and spatial resolution of fiber bundels were measured by means of two external reference detectors with a precision of 50 micron. The light output profile across fiber roads has been determined with the same accuracy. Different technologies were adopted for the construction of tracker modules consisting of 14 layers of 0.5 mm fibers and 0.7 mm pitch. A winding technology provides reliable results to produce later fiber modules of about 25 cm x 25 cm area. We conclude that on the basis of these results a fiber tracker for high rate conditions can be built.

E. C. Aschenauer; J. Baehr; V. Gapienko; B. Hoffmann; A. Kharchilava; H. Luedecke; R. Nahnhauer; R. Shanidze

1997-10-02

301

Breast cancer screening  

Microsoft Academic Search

Radiographic imaging of the breast began in the early years of the twentieth century. Continuous advances in film quality, energy sources, targets, grids, and filters have all contributed to superior image resolution. Federal quality standards now regulate screening mammography, and mass screening for breast cancer has become widely accepted in the United States. Wider application of screening has resulted in

Kathleen M. Harris; Victor G. Vogel

1997-01-01

302

OFFSET: Optical Fiber Folded Scintillating Extended Tracker  

NASA Astrophysics Data System (ADS)

The OFFSET collaboration aims at the development of a novel system for tracking charged particles, designed to achieve real-time imaging, large detection areas, and a high spatial resolution especially suitable for use in medical diagnostics. This paper presents the first prototype of this tracker, having a 20×20 cm2 sensitive area made by two crossed ribbons of 500 ?m square scintillating fibers. The track position information is extracted in real time using a reduced number of read-out channels to obtain very large detection area at moderate cost and complexity. The performance of the tracker was investigated using ? sources, cosmic rays and a 62 MeV proton beam.

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

2014-02-01

303

SSPM scintillator readout for gamma radiation detection  

NASA Astrophysics Data System (ADS)

Silicon-based photodetectors offer several benefits relative to photomultiplier tube-based scintillator systems. Solid-state photomultipliers (SSPM) can realize the gain of a photomultiplier tube (PMT) with the quantum efficiency of silicon. The advantages of the solid-state approach must be balanced with adverse trade-offs, for example from increased dark current, to optimize radiation detection sensitivity. We are designing a custom SSPM that will be optimized for green emission of thallium-doped cesium iodide (CsI(Tl)). A typical field gamma radiation detector incorporates thallium doped sodium iodide (NaI(Tl)) and a radiation converter with a PMT. A PMT's sensitivity peaks in the blue wavelengths and is well matched to NaI(Tl). This paper presents results of photomultiplier sensitivity relative to conventional SSPMs and discusses model design improvements. Prototype fabrications are in progress.

Baker, Stuart A.; Stapels, Christopher; Green, J. Andrew; Guise, Ronald E.; Young, Jason A.; Franks, Larry; Stokes, Britany; Wendelberger, Elizabeth

2011-09-01

304

The Oriented Scintillation Spectrometer Experiment - Instrument description  

NASA Technical Reports Server (NTRS)

The Oriented Scintillation Spectrometer Experiment on the Arthur Holly Compton Gamma Ray Observatory satellite uses four actively shielded NaI (Tl)-CsI(Na) phoswich detectors to provide gamma-ray line and continuum detection capability in the 0.05-10 MeV energy range. The instrument includes secondary capabilities for gamma-ray and neutron detection between 10 and 250 MeV. The detectors have 3.8 deg x 11.04 deg (FWHM) fields of view defined by tungsten collimators. Each detector has an independent, single-axis orientation system which permits offset pointing from the spacecraft Z-axis for background measurements and multitarget observations. The instrument, and its calibration and performance, are described.

Johnson, W. N.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.; Purcell, W. R.; Grabelsky, D. A.; Ulmer, M. P.; Hillis, D. A.; Jung, G. V.; Cameron, R. A.

1993-01-01

305

The Oriented Scintillation Spectrometer Experiment - Instrument description  

NASA Astrophysics Data System (ADS)

The Oriented Scintillation Spectrometer Experiment on the Arthur Holly Compton Gamma Ray Observatory satellite uses four actively shielded NaI (Tl)-CsI(Na) phoswich detectors to provide gamma-ray line and continuum detection capability in the 0.05-10 MeV energy range. The instrument includes secondary capabilities for gamma-ray and neutron detection between 10 and 250 MeV. The detectors have 3.8 deg x 11.04 deg (FWHM) fields of view defined by tungsten collimators. Each detector has an independent, single-axis orientation system which permits offset pointing from the spacecraft Z-axis for background measurements and multitarget observations. The instrument, and its calibration and performance, are described.

Johnson, W. N.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.; Purcell, W. R.; Grabelsky, D. A.; Ulmer, M. P.; Hillis, D. A.; Jung, G. V.; Cameron, R. A.

1993-06-01

306

Intensity Scintillation and Astronomical Quantum Observation  

E-print Network

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 include phased array,CCD, digital signal processing and supercomputer can achieve that digital and computer holography from radio to X-ray astronomy. This means we can use it to image the universe and beyond the limited of telescope for cosmos provide much coherent light from pulsar,maser, black hole to 21cm recombination line. It gives a probe to the medium of near the black hole et al. From those coherent light sources in the sky, we can uncover one different universe that through astronomical quantum observation which use intensity interference.

Jiang Dong

2008-12-14

307

Cancer Screening: How Do Screening Tests Become Standard Tests?  

MedlinePLUS

... cancer symptoms. There are different kinds of screening tests. Screening tests include the following: Physical exam and ... are linked to some types of cancer. Screening tests have risks. Not all screening tests are helpful ...

308

Improvement in Screening Radiologists' Performance in an Organized Screening Program  

Cancer.gov

Improvement in Screening Radiologists’ Performance in an Organized Screening Program Nancy A. T. Wadden, MD, FRCPC Gregory Doyle, BSc, MBA Breast Screening Program for Newfoundland and Labrador Canada Background • Breast Screening Program for Newfoundland

309

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

310

The UA2 scintillating fibre detector  

NASA Astrophysics Data System (ADS)

The UA2 experiment at CERN is currently upgrading its apparatus to take advantage of the higher accelerator luminosity to be provided from November 1987. The first large particle tracking detector using scintillating optical fibres will form a major part of this upgrade. The detector is built by the Cambridge, CERN and Saclay groups. The Scintillating Fibre Detector is a cylinder of radius 38 to 44 cm, composed of 60000 plastic optical fibres of length over 2 m. The 1 mm diameter fibres are optically clad and aluminised, and are arranged in 24 layers. The detector will be used to track charged particles produced in pp interactions, and also contains a lead converter to cause neutral and charged electromagnetic particles to shower. The signals from the fibres are amplified, multiplexed and digitised by 32 readout chains. These consist of: —A large aperture, de-magnifying image intensifier, providing a gain of ˜ 40000. Extremely fast phosphors are employed for the three stages, to match the short time (4 ps) between particle interactions; —Charge-coupled devices (CCDs) converting the optical image into a single train of electrical pulses for 2000 fibres. A novel use of the anti-blooming electrode of the CCD enables unwanted images to be cleared in <1 ps; —A Fastbus digitiser, which processes the video signal, providing a large degree of data reduction. A full-scale prototype of 960 fibres with readout has been tested in a particle beam. It has demonstrated a good spatial resolution of the tracks (< 0.20 mm), and an excellent discrimination between electrons and hadrons based on the light detected after the converter.

Ansorge, R. E.; Anrouet, C.; Bareyre, P.; Bonamy, P.; Booth, C. N.; Bouchard, M.; Bourdinaud, M.; Cordier, M.; Crittenden, J.; Dewolf, R. S.; Dupont, J.; Dupraz, J.; Einsweiler, K.; Engster, C.; Fabre, J.-P.; Gaillard, J.-M.; Garavel, J.-L.; Hultqvist, K.; Jeanney, C.; Katvars, S. G.; Lefebvre, M.; Linssen, L.; McCluskey, B.; Merkel, B.; Meyer, J.-P.; Munday, D. J.; Nappey, P.; Pentney, J. M.; Reynaud, S.; Rushbrooke, J. G.; Thevenin, J.-C.; Tsang, W. Y.; Weidberg, A. R.; Wells, P. S.; Wotton, S. A.; White, T. O.; Zaccone, H.

1988-12-01

311

Ionization and scintillation of nuclear recoils in gaseous xenon  

E-print Network

Ionization and scintillation produced by nuclear recoils in gaseous xenon at approximately 14 bar have been simultaneously observed in an electroluminescent time projection chamber. Neutrons from radioisotope $\\alpha$-Be neutron sources were used to induce xenon nuclear recoils, and the observed recoil spectra were compared to a detailed Monte Carlo employing estimated ionization and scintillation yields for nuclear recoils. The ability to discriminate between electronic and nuclear recoils using the ratio of ionization to primary scintillation is demonstrated. These results encourage further investigation on the use of xenon in the gas phase as a detector medium in dark matter direct detection experiments.

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

2014-09-09

312

Reduction of scintillation in optical modulating retro-reflector links.  

PubMed

Optical modulating retro-reflectors enable free-space optical links that have greatly reduced pointing requirements and do not require a laser at one end of the link. However, these types of links can exhibit very high optical scintillation due to the double passage of the beam through the atmosphere. This high scintillation causes fades and surges that can lead to packet errors in the link. It is shown that scintillation can be greatly reduced through a combination of techniques including retro-reflector diversity, aperture averaging and bistatic optical interrogation. Improvements of 20 dB in link performance are demonstrated. PMID:25402097

Rabinovich, W S; Mahon, R; Ferraro, M; Goetz, P G; Murphy, J L

2014-11-17

313

Ionization and scintillation of nuclear recoils in gaseous xenon  

E-print Network

Ionization and scintillation produced by nuclear recoils in gaseous xenon at approximately 14 bar have been simultaneously observed in an electroluminescent time projection chamber. Neutrons from radioisotope $\\alpha$-Be neutron sources were used to induce xenon nuclear recoils, and the observed recoil spectra were compared to a detailed Monte Carlo employing estimated ionization and scintillation yields for nuclear recoils. The ability to discriminate between electronic and nuclear recoils using the ratio of ionization to primary scintillation is demonstrated. These results encourage further investigation on the use of xenon in the gas phase as a detector medium in dark matter direct detection experiments.

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

2014-01-01

314

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

315

Trigger and electronics issues for scintillating fiber tracking  

SciTech Connect

Scintillating Fiber technology has made great advances and has demonstrated great promise for high speed charged particle tracking and triggering. The small detector sizes and fast scintillation floors available, make them very promising for use at high luminosity experiments at today`s and tomorrow`s colliding and fixed target experiments where high rate capability is essential. This paper will discuss some of the system aspects which should be considered by anyone attempting to design a scintillating fiber tracking system and high speed tracking trigger. As the reader will see, seemingly simple decisions can have far reaching effects on overall system performance.

Baumbaugh, A.E.

1994-01-01

316

Comparison of scintillators for single shot imaging of laser accelerated proton beams  

NASA Astrophysics Data System (ADS)

The application of intense laser pulses incident on specialized targets provides exciting new means for generating energetic beams of protons and ions. Recent work has demonstrated the utility of these beams of particles in a variety of applications, from inertial confinement fusion to radiation therapy. These applications require precise control, and subsequently precise feedback from the beam. Imaging techniques can provide the necessary shot-to-shot characterization to be effective as diagnostics. However, the utility of imaging methods scales with the capability of scintillating materials to emit well characterized and consistent radiation upon irradiance by a charged particle beam. We will discuss three candidates for an ideal diagnostic for MeV range protons and light ions. CsI:Tl^+ and Al2O3:Cr^3+ are two inorganic scintillators which exhibit excellent response to hadrons in this energy range. They are compared with the combination diagnostic micro-channel plate with a P43 phosphor screen, which offers advantages in refresh rate and resolution over direct exposure methods. Ultimately we will determine which candidate performs optimally as part of a robust, inexpensive diagnostic for laser accelerated protons and light ions.

Cook, Nathan

2012-03-01

317

Development of a fast scintillator based beam phase measurement system for compact superconducting cyclotrons  

SciTech Connect

In an isochronous cyclotron, measurements of central phase of the ion beam with respect to rf and the phase width provide a way to tune the cyclotron for maximum energy gain per turn and efficient extraction. We report here the development of a phase measurement system and the measurements carried out at the Variable Energy Cyclotron Centre's (VECC's) K= 500 superconducting cyclotron. The technique comprises detecting prompt {gamma}-rays resulting from the interaction of cyclotron ion beam with an aluminium target mounted on a radial probe in coincidence with cyclotron rf. An assembly comprising a fast scintillator and a liquid light-guide inserted inside the cyclotron was used to detect the {gamma}-rays and to transfer the light signal outside the cyclotron where a matching photo-multiplier tube was used for light to electrical signal conversion. The typical beam intensity for this measurement was a few times 10{sup 11} pps.

Bhattacharjee, Tanushyam; Kanti Dey, Malay; Dhara, Partha; Roy, Suvodeep; Debnath, Jayanta; Balakrishna Bhole, Rajendra; Dutta, Atanu; Pradhan, Jedidiah; Pal, Sarbajit; Pal, Gautam; Roy, Amitava; Chakrabarti, Alok [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata 700064 (India)

2013-05-15

318

Development of a fast scintillator based beam phase measurement system for compact superconducting cyclotrons.  

PubMed

In an isochronous cyclotron, measurements of central phase of the ion beam with respect to rf and the phase width provide a way to tune the cyclotron for maximum energy gain per turn and efficient extraction. We report here the development of a phase measurement system and the measurements carried out at the Variable Energy Cyclotron Centre's (VECC's) K = 500 superconducting cyclotron. The technique comprises detecting prompt ?-rays resulting from the interaction of cyclotron ion beam with an aluminium target mounted on a radial probe in coincidence with cyclotron rf. An assembly comprising a fast scintillator and a liquid light-guide inserted inside the cyclotron was used to detect the ?-rays and to transfer the light signal outside the cyclotron where a matching photo-multiplier tube was used for light to electrical signal conversion. The typical beam intensity for this measurement was a few times 10(11) pps. PMID:23742541

Bhattacharjee, Tanushyam; Kanti Dey, Malay; Dhara, Partha; Roy, Suvodeep; Debnath, Jayanta; Balakrishna Bhole, Rajendra; Dutta, Atanu; Pradhan, Jedidiah; Pal, Sarbajit; Pal, Gautam; Roy, Amitava; Chakrabarti, Alok

2013-05-01

319

Time and position sensitive single photon detector for scintillator read-out  

E-print Network

We have developed a photon counting detector system for combined neutron and gamma radiography which can determine position, time and intensity of a secondary photon flash created by a high-energy particle or photon within a scintillator screen. The system is based on a micro-channel plate photomultiplier concept utilizing image charge coupling to a position- and time-sensitive read-out anode placed outside the vacuum tube in air, aided by a standard photomultiplier and very fast pulse-height analyzing electronics. Due to the low dead time of all system components it can cope with the high throughput demands of a proposed combined fast neutron and dual discrete energy gamma radiography method (FNDDER). We show tests with different types of delay-line read-out anodes and present a novel pulse-height-to-time converter circuit with its potential to discriminate gamma energies for the projected FNDDER devices for an automated cargo container inspection system (ACCIS).

Sven Schössler; Benjamin Bromberger; Michal Brandis; Lothar Ph. H. Schmidt; Kai Tittelmeier; Achim Czasch; Volker Dangendorf; Ottmar Jagutzki

2012-02-10

320

Time profile of the scintillation from liquid and gaseous xenon  

NASA Astrophysics Data System (ADS)

The decay time profile of vacuum ultraviolet scintillation induced by electronic recoils has been studied for liquid and gaseous xenon. The scintillation light from xenon excited by a gamma source was measured by using two vacuum ultraviolet sensitive photomultipliers, one for detecting scintillation and the other for counting photons of weak monochromatic light. The analysis results based on the time-correlated single photon counting method show that the time profile in the 176 nm scintillation decay curve for liquid xenon is consistent with a single exponential component and the decay time constant is 31.5±1.3 ns. This constant does not change significantly for pressure ranges between 90 kPa and 130 kPa. There is no emission wavelength dependence of the decay constant. The result corresponds to an average on electronic recoil energies up to 1.3 MeV.

Murayama, Ikuko; Nakamura, Shogo

2014-11-01

321

Novel radiation hard microfabricated scintillation detectors with high spatial resolution  

E-print Network

of a single channel with a serpentine geometry. The operation of such a device is very simple as it has only one inlet and one outlet. Once filled with liquid scintillator it comes to be a densely packed array

Dalang, Robert C.

322

The response of scintillators to heavy ions: 1, Plastics  

SciTech Connect

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

McMahan, M.A.

1987-10-01

323

Bismuth germanate scintillators: applications in nuclear safeguards and health physics  

SciTech Connect

Bismuth germanate (BGO) scintillators are preferable to NaI(Tl) scintillators or germanium detectors for some applications in nuclear safeguards and health physics. The first system, which consists of eight scintillators and a computer-based data acquisition system, is very efficient. The second, which consists of one scintillator and a small analyzer, is less efficient but portable. A computer code that uses measured response functions and photopeak efficiencies, unfolds the BGO distributions measured with these systems to determine gamma-ray flux spectra and dose rates. One application of these systems is the accurate determination of flux spectra and dose rates from containers of uranium or plutonium. A second application determined these quantities from a replica of Little Boy, the device exploded over Hiroshima. 7 refs., 6 figs.

Moss, C.E.; Dowdy, E.J.; Lucas, M.C.

1985-05-01

324

Scintillation properties of ceramics based on zinc oxide  

E-print Network

Ceramics ZnO:Zn of 20mm diameter and 1.6mm thickness with an optical transparency up to 0.33 in the visible region have been prepared by hot pressing technique. Scintillating and luminescent characteristics such as emission spectra, decay time, yield, and TSL glow curve have been measured under X-ray excitation. Two emission bands peaking at 500 and 380 nm were detected, the light output was about 80% of that for standard BGO scintillator, main decay constant was 10.4 +/- 0.1 ns. The obtained data allow us to consider the ZnO:Zn ceramics as a perspective scintillator. Finally, the investigation shows that other ZnO-based fast scintillators can be fabricated in the form of optical ceramics.

V. A. Demidenko; E. I. Gorokhova; I. V. Khodyuk; O. A. Khristich; S. B. Mikhrin; P. A. Rodnyi

2010-09-07

325

Scintillation properties of ceramics based on zinc oxide  

E-print Network

Ceramics ZnO:Zn of 20mm diameter and 1.6mm thickness with an optical transparency up to 0.33 in the visible region have been prepared by hot pressing technique. Scintillating and luminescent characteristics such as emission spectra, decay time, yield, and TSL glow curve have been measured under X-ray excitation. Two emission bands peaking at 500 and 380 nm were detected, the light output was about 80% of that for standard BGO scintillator, main decay constant was 10.4 ± 0.1 ns. The obtained data allow us to consider the ZnO:Zn ceramics as a perspective scintillator. Finally, the investigation shows that other ZnO-based fast scintillators can be fabricated in the form of optical ceramics.

Demidenko, V A; Khodyuk, I V; Khristich, O A; Mikhrin, S B; Rodnyi, P A

2010-01-01

326

Measurement of Propagation Time Dispersion in a Scintillator  

E-print Network

One contribution to the time resolution of a scintillation detector is the signal time spread due to path length variations of the detected photons from a point source. In an experimental study a rectangular scintillator was excited by means of a fast pulsed ultraviolet laser at different positions along its longitudinal axis. Timing measurements with a photomultiplier tube in a detection plane displaced from the scintillator end face showed a correlation between signal time and tube position indicating only a small distortion of photon angles during transmission. The data is in good agreement with a Monte Carlo simulation used to compute the average photon angle with respect to the detection plane and the average propagation time. Limitations on timing performance that arise from propagation time dispersion are expected for long and thin scintillators used in future particle identification systems.

P. Achenbach; C. Ayerbe Gayoso; J. Bernauer; R. Böhm; M. O. Distler; L. Doria; J. Friedrich; H. Merkel; U. Müller; L. Nungesser; J. Pochodzalla; S. Sánchez Majos; S. Schlimme; Th. Walcher; M. Weinriefer

2007-02-25

327

CaF2(Eu): an ``old'' scintillator revisited  

NASA Astrophysics Data System (ADS)

Homeland security applications demand performant two-plane Compton-camera systems, with high detector efficiency, good nuclide identification and able to perform in-field conditions. A low-Z scintillator has been proposed and studied as a promising candidate for use in the scattering plane of a scintillator-based Compton camera: CaF2(Eu) [1]. All the relevant properties for the application of this scintillator in a mobile Compton camera system, have been addressed: the energy resolution and the non-proportionality at room temperature and in the temperature range of -20°C to +55°C, the photoelectron yield and the relative light yield in the relevant temperature range. A new method of inferring the relative light output of scintillators has been proposed.

Plettner, C.; Pausch, G.; Scherwinski, F.; Herbach, C. M.; Lentering, R.; Kong, Y.; Römer, K.; Grodzicka, M.; Szcze?niak, T.; Iwanowska, J.; Moszy?ski, M.

2013-06-01

328

21 CFR 892.1100 - Scintillation (gamma) camera.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1100 Scintillation (gamma) camera. (a) Identification. A...

2013-04-01

329

21 CFR 892.1100 - Scintillation (gamma) camera.  

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1100 Scintillation (gamma) camera. (a) Identification. A...

2014-04-01

330

21 CFR 892.1100 - Scintillation (gamma) camera.  

Code of Federal Regulations, 2012 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1100 Scintillation (gamma) camera. (a) Identification. A...

2012-04-01

331

21 CFR 892.1100 - Scintillation (gamma) camera.  

Code of Federal Regulations, 2010 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1100 Scintillation (gamma) camera. (a) Identification. A...

2010-04-01

332

21 CFR 892.1100 - Scintillation (gamma) camera.  

Code of Federal Regulations, 2011 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1100 Scintillation (gamma) camera. (a) Identification. A...

2011-04-01

333

AARHUS UNIVERSITET INVENTOR'S GUIDE  

E-print Network

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Case Story: Commercializing a diagnostic Technology Gave Added Benefits to ResearchersAARHUS UNIVERSITET INVENTOR'S GUIDE TO TECHNOLOGY TRANSFER AT AARHUS UNIVERSITY #12;#12;AARHUS UNIVERSITY INVENTOR'S GUIdE 3 The Technology Transfer Process

334

Scintillation response of liquid xenon to low energy nuclear recoils  

Microsoft Academic Search

Liquid Xenon (LXe) is expected to be an excellent target and detection medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). We have measured the scintillation efficiency of nuclear recoils with kinetic energy between 10.4 and 56.5 keV relative to that of 122 keV gamma rays from C57o. The scintillation yield of 56.5 keV

E. Aprile; K. L. Giboni; P. Majewski; K. Ni; M. Yamashita; R. Hasty; A. Manzur; D. N. McKinsey

2005-01-01

335

Li-containing scintillating bolometers for low background physics  

NASA Astrophysics Data System (ADS)

We present the performances of Li-based compounds used as scintillating bolometer for rare decay studies such as double-beta decay and direct dark matter investigations. The compounds are tested in a dilution refrigerator installed in the underground laboratory of Laboratori Nazionali del Gran Sasso (Italy). Low temperature scintillating properties are investigated by means of different radioactive sources, and the radio-purity level for internal contaminations are estimated for possible employment for next generation experiments.

Pattavina, L.

2014-01-01

336

Recent developments in avalanche photodiodes for scintillating fiber applications  

NASA Astrophysics Data System (ADS)

Research is ongoing to tailor proportional mode avalanche photodiodes (APDs) for use in nuclear radiation environments and for scintillating fiber readout. We report progress on APD design modifications directed toward minimizing signals from ionizing particle interactions and also toward producing APD arrays for scintillating fiber readout. In addition, we present results for very high gain APDs fabricated using a new planar process which shows great promise for lower production costs of both APD arrays and discrete devices.

Farrell, Richard; Vanderpuye, Kofi; Vasile, Stefan; Gordon, Jeffrey S.; Gothoskar, Prakash

1998-11-01

337

Monitoring the solar-terrestrial environment using interplanetary scintillation  

NASA Astrophysics Data System (ADS)

Before being detected on Earth, radio waves from a celestial source pass through the interplanetary medium, where they undergo diffraction by plasma density variations in the solar wind, making them appear to scintillate. The amount of scintillation observed can be used to infer the electron density along the line-of-sight to the source. Therefore, when observing many sources across the sky, the solar wind can be mapped out daily. Observations taken over a 5 year period (1990-94) with the Cambridge IPS array are now being analysed at Glasgow. Man-made interference, from sources such as domestic appliances and car engines, is a significant problem in much of these data. Obviously, to get the most out of the data, this noise must be dealt with properly. Another problem is caused by scintillation in the ionosphere. We must be able to distinguish between scintillation caused by the ionosphere, and that caused by the interplanetary medium. Using a model for the expected scintillation profile and timescale for each radio source, it is possible to cut out noise, and to identify periods of ionospheric scintillation in the data. The fitting procedure returns an estimate of both the scintillating power of the source, and the scintillation frequency, which can in turn be used to measure both the density and speed of the solar wind over the whole sky. From this, it's possible to track transient events in the interplanetary medium, such as Coronal Mass Ejections. This whole-sky picture has several advantages over a localised measurement given by an in-situ spacecraft.

Daly, N.

338

Liquid scintillators and composites in fast neutron detection  

NASA Astrophysics Data System (ADS)

Helium-3 world crisis requires a development of new methods of neutron detection to replace commonly used 3He proportional counters. One of the option is application of liquid scintillators widely used in detection of fast neutrons, mostly in physics experiments, especially in applications where large volumes are required. Moreover, recently studied 10B loaded liquid scintillators cover detection of neutrons down to thermal energy. The several years' studies of liquid scintillators in our laboratory, brought us a knowledge about their efficiency to neutron detection, gamma sensitivity, etc. We have also tested composite scintillators, which are an alternative to organic single crystals, used in the 70's last century. In the report, we will present the results of the study of several liquid scintillators, also 10B loaded, as well as high flashpoint ones. We also show the neutron detection properties of some samples of composite scintillators. Composites are based on small grains of p-terphenyl or stilbene, introduced into a polymer matrix, which acts as a diffuser. The composite is encapsulated in a housing made of organic glass. P-terphenyl and stilbene are organic scintillators, which were commonly used in the seventies last century. They are characterized by good neutron/gamma discrimination properties. The present studies covers neutron/gamma discrimination by the zero-crossing method, a comparison of detection efficiency of liquid scintillators to 3He detectors and methods to reduce their gamma-ray sensitivity. In conclusion, a detection system, based on several small liquid cells of 2'' × 2'', is preferred, with pulse shape discrimination circuit equipped with the pile-up rejection circuit (PUR), as well as lead and tin shielding.

Iwanowska, J.; Swiderski, L.; Moszynski, M.

2012-04-01

339

Investigation of lanthanum scintillators for 3-D PET  

Microsoft Academic Search

The main thrust for this work is the investigation and design of a positron emission tomography (PET) scanner based on new Lanthanum Halide scintillators. In three-dimensional (3-D) PET the major limitations are scanner dead-time and ability to reject randoms and scatter. Therefore, to reach the full potential of 3-D PET requires a scintillator with good timing resolution and good energy

S. Surti; J. S. Karp; G. Muehllehner; P. S. Raby

2003-01-01

340

Lanthanum Halide Nanoparticle Scintillators for Nuclear Radiation Detection  

SciTech Connect

Nanoparticles with sizes <10 nm were fabricated and characterized for their nanocomposite radiation detector properties. This work investigated the properties of several nanostructured radiation scintillators, in order to determine the viability of using scintillators employing nanostructured lanthanum tribromide, lanthanum trifluoride, or cerium tribromide. Preliminary results of this investigation are consistent with the idea that these materials have an intrinsic response to nuclear radiation that may be correlated to the energy of the incident radiation.

Guss, P. P., Guise, R., Yuan, D., Mukhopadhyay, S., O'Brien, R., Lowe, D.

2013-02-01

341

A comparison of TEC fluctuations and scintillations at Ascension Island  

Microsoft Academic Search

With increasing reliance on space-based platforms for global navigation and communication, concerns about the impact of ionospheric scintillation on these systems have become a high priority. Recently, the Air Force Research Laboratory (AFRL) performed amplitude scintillation measurements of L1 (1.575 MHz) signals from GPS satellites at Ascension Island (14.45° W, 7.95° S; magnetic latitude 16° S) during February–April, 1998, to compare

S Basu; K. M Groves; J. M Quinn; P Doherty

1999-01-01

342

Lanthanum halide nanoparticle scintillators for nuclear radiation detection  

SciTech Connect

Nanoparticles with sizes <10 nm were fabricated and characterized for their nanocomposite radiation detector properties. This work investigated the properties of several nanostructured radiation scintillators, in order to determine the viability of using scintillators employing nanostructured lanthanum trifluoride. Preliminary results of this investigation are consistent with the idea that these materials have an intrinsic response to nuclear radiation that may be correlated to the energy of the incident radiation.

Guss, Paul; Guise, Ronald [Remote Sensing Laboratory, P.O. Box 98521, M/S RSL-48, Las Vegas, Nevada 89193 (United States); Yuan Ding [National Security Technologies, LLC, Los Alamos Operations, P.O. Box 809, M/S LAO/C320, Los Alamos, New Mexico 87544 (United States); Mukhopadhyay, Sanjoy [Remote Sensing Laboratory-Andrews, Building 1783, Arnold Avenue Andrews AFB, Maryland 20762 (United States); O'Brien, Robert; Lowe, Daniel [University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, Nevada 89154 (United States); Kang Zhitao; Menkara, Hisham [Georgia Tech Research Institute, 925 Dalney St., Atlanta, Georgia 30332 (United States); Nagarkar, Vivek V. [RMD, Inc., 44 Hunt Street, Watertown, Massachusetts 02472 (United States)

2013-02-14

343

Decay time and light yield measurements for plastic scintillating fibers  

Microsoft Academic Search

We have studied light production and propagation in three different samplesof plastic scintillating fibers manufactured by Kyowa Gas Co.: SCSF-81, SCSF-38 and SCSF-38 with afquenching additive. The emissio time distribution is described phenomenologically by a fast two-step scintillation process and an additional slow component, the time constants of which are determined. The light yield from the fibers is measured as

C. M. Hawkes; M. Kuhlen; B. Milliken; R. Stroynowski; E. Wicklund; T. Shimizu; O. Shinji

1990-01-01

344

Fluorescence decay-time constants in organic liquid scintillators  

SciTech Connect

The fluorescence decay-time constants have been measured for several scintillator mixtures based on phenyl-o-xylylethane (PXE) and linear alkylbenzene (LAB) solvents. The resulting values are of relevance for the physics performance of the proposed large-volume liquid scintillator detector Low Energy Neutrino Astronomy (LENA). In particular, the impact of the measured values to the search for proton decay via p{yields}K{sup +}{nu} is evaluated in this work.

Marrodan Undagoitia, T. [Physik-Department, Technische Universitaet Muenchen, James-Franck-Str., 85748 Garching (Germany); Physik-Institut, Universitaet Zuerich, Winterthurerstr. 190, 8057 Zuerich (Switzerland); Feilitzsch, F. von; Oberauer, L.; Potzel, W.; Ulrich, A.; Winter, J.; Wurm, M. [Physik-Department, Technische Universitaet Muenchen, James-Franck-Str., 85748 Garching (Germany)

2009-04-15

345

Fluorescence decay-time constants in organic liquid scintillators  

E-print Network

The fluorescence decay-time constants have been measured for several scintillator mixtures based on phenyl-o-xylylethane (PXE) and linear alkylbenzene (LAB) solvents. The resulting values are of relevance for the physics performance of the proposed large-volume liquid scintillator detector LENA (Low Energy Neutrino Astronomy). In particular, the impact of the measured values to the search for proton decay via p -> K+ antineutrino is evaluated in this work.

Undagoitia, T Marrodan; Oberauer, L; Potzel, W; Ulrich, A; Winter, J; Wurm, M; 10.1063/1.3112609

2009-01-01

346

Fluorescence decay-time constants in organic liquid scintillators  

NASA Astrophysics Data System (ADS)

The fluorescence decay-time constants have been measured for several scintillator mixtures based on phenyl-o-xylylethane (PXE) and linear alkylbenzene (LAB) solvents. The resulting values are of relevance for the physics performance of the proposed large-volume liquid scintillator detector Low Energy Neutrino Astronomy (LENA). In particular, the impact of the measured values to the search for proton decay via p ?K+?¯ is evaluated in this work.

Marrodán Undagoitia, T.; von Feilitzsch, F.; Oberauer, L.; Potzel, W.; Ulrich, A.; Winter, J.; Wurm, M.

2009-04-01

347

High effective atomic number polymer scintillators for gamma ray spectroscopy  

DOEpatents

A scintillator material according to one embodiment includes a bismuth-loaded aromatic polymer having an energy resolution at 662 keV of less than about 10%. A scintillator material according to another embodiment includes a bismuth-loaded aromatic polymer having a fluor incorporated therewith and an energy resolution at 662 keV of less than about 10%. Additional systems and methods are also presented.

Cherepy, Nerine Jane; Sanner, Robert Dean; Payne, Stephen Anthony; Rupert, Benjamin Lee; Sturm, Benjamin Walter

2014-04-15

348

Hadronic shower development in Iron-Scintillator Tile Calorimetry  

Microsoft Academic Search

The lateral and longitudinal profiles of hadronic showers detected by a prototype of the ATLAS Iron-Scintillator Tile Hadron Calorimeter have been investigated. This calorimeter presents a unique longitudinal configuration of scintillator tiles. Using a fine-grained pion beam scan at 100GeV, a detailed picture of transverse shower behaviour is obtained. The underlying radial energy densities for the four depth segments and

P. Amaral; A. Amorim; K. Anderson; G. Barreira; R. Benetta; S. Berglund; C. Biscarat; G. Blanchot; E. Blucher; A A Bogush; C. Bohm; V. Boldea; O. Borisov; M. Bosman; C. Bromberg; J. Budagov; S. Burdin; L. Caloba; J. Carvalho; P. Casado; M. V. Castillo; M. Cavalli-Sforza; V. Cavasinni; R. Chadelas; I E Chirikov-Zorin; G. Chlachidze; M. Cobal; F. Cogswell; F. Colaço; S. Cologna; S. Constantinescu; D. Costanzo; M. Crouau; F. Daudon; J. David; M. David; T. Davidek; J. Dawson; K. De; T. Del Prete; A. De Santo; B. Di Girolamo; S. Dita; J. Dolejsi; Z. Dolezal; R. Downing; I. Efthymiopoulos; M. Engström; D. Errede; S. Errede; H. Evans; A. Fenyuk; A. Ferrer; V. Flaminio; E. Gallas; M. Gaspar; I. Gil; O. Gildemeister; V. Glagolev; A. Gomes; V. Gonzalez; S. González De La Hoz; V Grabskii; E Graugès-Pous; P. Grenier; H H Hakopian; M. Haney; M. Hansen; S. Hellman; A. Henriques; C. Hebrard; E. Higon; S O Holmgren; J. Huston; Yu M Ivanyushenkov; A. Juste; S. Kakurin; G V Karapetian; A N Karyukhin; S. Kopikov; V. Kukhtin; Y. Kulchitsky; W. Kurzbauer; M. Kuzmin; S. Lami; V. Lapin; C. Lazzeroni; A. Lebedev; R. Leitner; J. Li; Yu F Lomakin; O V Lomakina; M. Lokajicek; J. M. Lopez Amengual; A. Maio; S. Malyukov; F. Marroquin; J. P. Martins; E. Mazzoni; F S Merritt; R. Miller; I A Minashvili; Ll. Miralles; G. Montarou; A. Munar; S. Nemecek; Marzio Nessi; A. Onofre; S. Orteu; I. C. Park; D. Pallin; D. Pantea; R. Paoletti; J. Patriarca; A. Pereira; J. A. Perlas; P. Petit; J E Pilcher; L. Poggioli; L. Price; J. Proudfoot; O. Pukhov; G. Reinmuth; G. Renzoni; R. Richards; C. Roda; J. B. Romance; V. Romanov; B. Ronceux; P. Rosnet; V. Rumyantsev; N. Russakovich; E. Sanchis; H. Sanders; C. Santoni; J. Santos; L. Sawyer; L.-P. Says; J. M. Seixas; B. Selldèn; A. Semenov; A S Shchelchkov; M. Shochet; V. Simaitis; A N Sissakian; A. Solodkov; O. Solovianov; P. Sonderegger; M. Sosebee; K. Soustruznik; F. Spanó; R. Stanek; E A Starchenko; R. Stephens; M. Suk; F. Tang; P. Tas; J. Thaler; S. Tokar; N. Topilin; Z. Trka; A S Turcot; M. Turcotte; S. Valkar; M. J. Varandas; A H Vartapetian; F. Vazeille; I. Vichou; V. Vinogradov; S B Vorozhtsov; D. Wagner; A. White; H. Wolters; N. Yamdagni; G. Yarygin; C. Yosef; A. Zaitsev; M. Zdrazil

2000-01-01

349

Machining of scintillator tiles for the SDC calorimeter  

Microsoft Academic Search

This research and development on the grooving methods for the scintillating tiles of the SDC calorimeter was done to maximize the light output of scintillator plates and improve the uniformity among tiles through machining procedures. Grooves for wavelength shifting fibers in SCSN-81 can be machined from 10,000 to 60,000 RPM with a feed rate of more than 30 cm\\/min if

M. Bertoldi; E. Bartosz; C. Davis; V. Hagopian; E. Hernandez; K. Hu; C. Immer; J. Thomaston

1993-01-01

350

Broadband meter-wavelength observations of ionospheric scintillation  

NASA Astrophysics Data System (ADS)

Intensity scintillations of cosmic radio sources are used to study astrophysical plasmas like the ionosphere, the solar wind, and the interstellar medium. Normally, these observations are relatively narrow band. With Low-Frequency Array (LOFAR) technology at the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) station in northern Finland we have observed scintillations over a three-octave bandwidth. "Parabolic arcs," which were discovered in interstellar scintillations of pulsars, can provide precise estimates of the distance and velocity of the scattering plasma. Here we report the first observations of such arcs in the ionosphere and the first broadband observations of arcs anywhere, raising hopes that study of the phenomenon may similarly improve the analysis of ionospheric scintillations. These observations were made of the strong natural radio source Cygnus-A and covered the entire 30-250 MHz band of KAIRA. Well-defined parabolic arcs were seen early in the observations, before transit, and disappeared after transit although scintillations continued to be obvious during the entire observation. We show that this can be attributed to the structure of Cygnus-A. Initial results from modeling these scintillation arcs are consistent with simultaneous ionospheric soundings taken with other instruments and indicate that scattering is most likely to be associated more with the topside ionosphere than the F region peak altitude. Further modeling and possible extension to interferometric observations, using international LOFAR stations, are discussed.

Fallows, R. A.; Coles, W. A.; McKay-Bukowski, D.; Vierinen, J.; Virtanen, I. I.; Postila, M.; Ulich, Th.; Enell, C.-F.; Kero, A.; Iinatti, T.; Lehtinen, M.; Orispää, M.; Raita, T.; Roininen, L.; Turunen, E.; Brentjens, M.; Ebbendorf, N.; Gerbers, M.; Grit, T.; Gruppen, P.; Meulman, H.; Norden, M. J.; de Reijer, J.-P.; Schoenmakers, A.; Stuurwold, K.

2014-12-01

351

Observations of GPS scintillation during an isolated auroral substorm  

NASA Astrophysics Data System (ADS)

This paper reports simultaneous observations of ionospheric scintillation during an auroral substorm that were made using an all-sky full-color digital single-lens reflex (DSLR) camera (ASC) and a Global Positioning System (GPS) ionospheric scintillation and total electron content monitor (GISTM) in Tromsø (69.60 N, 19.20 E), Norway. On the night of November 19, 2009, a small substorm occurred in northern Scandinavia. The ASC captured its temporal evolution from the beginning of the growth phase to the end of the recovery phase. The amplitude scintillation, as monitored by the S4 index from the GISTM, did not increase in any substorm phase. By contrast, phase scintillation, as measured by the ? ? index, occurred when discrete auroral arcs appeared on the GPS signal path. In particular, the phase scintillation was significantly enhanced for a few minutes immediately after the onset of the expansion phase. During this period, bright and discrete auroral forms covered the entire sky, which implies that structured precipitation on the scale of a few kilometers to a few tens of kilometers dominated the electron density distribution in the E region. Such inhomogeneous ionization structures probably produced significant changes in the refractive index and eventually resulted in the enhancement of the phase scintillation.

Hosokawa, Keisuke; Otsuka, Yuichi; Ogawa, Yasunobu; Tsugawa, Takuya

2014-12-01

352

Effects of atmospheric scintillation in Ka-band satellite communications  

NASA Astrophysics Data System (ADS)

This research is motivated by the need to characterize the effects of atmospheric scintillation on Ka-band satellite communications. The builders of satellite communications systems are planning to utilize Ka-band in more than a dozen systems that have been proposed for launch in the next decade. The NASA ACTS (Advanced Communication Technology Satellite) program has provided a means to investigate the problems associated with Ka-band satellite transmissions. Experimental measurements have been conducted using a very small aperture terminal (VSAT) to evaluate the effects of scintillation on narrowband and wideband signals. The theoretical background of scintillation theory is presented, noting especially the additional performance degradation predicted for wideband Ka-band systems using VSATs. Experimental measurements of the amplitude and phase variations in received narrowband carrier signals were performed, using beacon signals transmitted by ACTS and carrier signals which are relayed through the satellite. Measured amplitude and phase spectra have been compared with theoretical models to establish the presence of scintillation. Measurements have also been performed on wideband spread spectrum signals which are relayed through ACTS to determine the bit-error rate degradation of the digital signal resulting from scintillation effects. The theory and measurements presented for the geostationary ACTS have then been applied to a low-earth orbiting satellite system, by extrapolating the effects of the moving propagation path on scintillation.

Borgsmiller, Scott A.

353

Fast neutron detection with 6Li-loaded liquid scintillator  

NASA Astrophysics Data System (ADS)

We report on the development of a fast neutron detector using a liquid scintillator doped with enriched 6Li. The lithium was introduced in the form of an aqueous LiCl micro-emulsion with a di-isopropylnaphthalene-based liquid scintillator. A 6Li concentration of 0.15% by weight was obtained. A 125 mL glass cell was filled with the scintillator and irradiated with fission-source neutrons. Fast neutrons may produce recoil protons in the scintillator, and those neutrons that thermalize within the detector volume can be captured on the 6Li. The energy of the neutron may be determined by the light output from recoiling protons, and the capture of the delayed thermal neutron reduces background events. In this paper, we discuss the development of this 6Li-loaded liquid scintillator, demonstrate the operation of it in a detector, and compare its efficiency and capture lifetime with Monte Carlo simulations. Data from a boron-loaded plastic scintillator were acquired for comparison. We also present a pulse-shape discrimination method for differentiating between electronic and nuclear recoil events based on the Matusita distance between a normalized observed waveform and nuclear and electronic recoil template waveforms. The details of the measurements are discussed along with specifics of the data analysis and its comparison with the Monte Carlo simulation.

Fisher, B. M.; Abdurashitov, J. N.; Coakley, K. J.; Gavrin, V. N.; Gilliam, D. M.; Nico, J. S.; Shikhin, A. A.; Thompson, A. K.; Vecchia, D. F.; Yants, V. E.

2011-08-01

354

High energy resolution with transparent ceramic garnet scintillators  

NASA Astrophysics Data System (ADS)

Breakthrough energy resolution, R(662keV) < 4%, has been achieved with an oxide scintillator, Cerium-doped Gadolinium Yttrium Gallium Aluminum Garnet, or GYGAG(Ce). Transparent ceramic GYGAG(Ce), has a peak emission wavelength of 550 nm that is better matched to Silicon photodetectors than to standard PMTs. We are therefore developing a spectrometer based on pixelated GYGAG(Ce) on a Silicon photodiode array that can provide R(662 keV) = 3.6%. In comparison, with large 1-2 in3 size GYGAG(Ce) ceramics we obtain R(662 keV) = 4.6% with PMT readout. We find that ceramic GYGAG(Ce) of a given stoichiometric chemical composition can exhibit very different scintillation properties, depending on sintering conditions and post-anneal treatments. Among the characteristics of transparent ceramic garnet scintillators that can be controlled by fabrication conditions are: scintillation decay components and their amplitudes, intensity and duration of afterglow, thermoluminescence glow curve peak positions and amplitudes, integrated light yield, light yield non-proportionality - as measured in the Scintillator Light Yield Non-Proportionality Characterization Instrument (SLYNCI), and energy resolution for gamma spectroscopy. Garnet samples exhibiting a significant fraction of Cerium dopant in the tetravalent valence also exhibit: faster overall scintillation decay, very low afterglow, high light yield, but poor light yield proportionality and degraded energy resolution.

Cherepy, N. J.; Seeley, Z. M.; Payne, S. A.; Beck, P. R.; Swanberg, E. L.; Hunter, S.; Ahle, L.; Fisher, S. E.; Melcher, C.; Wei, H.; Stefanik, T.; Chung, Y.-S.; Kindem, J.

2014-09-01

355

Infrared scintillation yield in gaseous and liquid argon  

E-print Network

The study of primary and secondary scintillations in noble gases and liquids is of paramount importance to rare-event experiments using noble gas media. In the present work, the scintillation yield in gaseous and liquid Ar has for the first time been measured in the near infrared (NIR) and visible region, both for primary and secondary (proportional) scintillations, using Geiger-mode avalanche photodiodes (G-APDs) and pulsed X-ray irradiation. The primary scintillation yield of the fast component was measured to be 17000 photon/MeV in gaseous Ar in the NIR, in the range of 690-1000 nm, and 510 photon/MeV in liquid Ar, in the range of 400-1000 nm. Proportional NIR scintillations (electroluminescence) in gaseous Ar have been also observed; their amplification parameter at 163 K was measured to be 13 photons per drifting electron per kV. Possible applications of NIR scintillations in high energy physics experiments are discussed.

A. Buzulutskov; A. Bondar; A. Grebenuk

2011-04-19

356

Response of plastic scintillators to low-energy photons  

NASA Astrophysics Data System (ADS)

Diagnostic radiology typically uses x-ray beams between 25 and 150?kVp. Plastic scintillation detectors (PSDs) are potentially successful candidates as field dosimeters but careful selection of the scintillator is crucial. It has been demonstrated that they can suffer from energy dependence in the low-energy region, an undesirable dosimeter characteristic. This dependence is partially due to the nonlinear light yield of the scintillator to the low-energy electrons set in motion by the photon beam. In this work, PSDs made of PMMA, PVT or polystyrene were studied for the x-ray beam range 25 to 100?kVp. For each kVp data has been acquired for additional aluminium filtrations of 0.5, 1.0, 2.0 and 4.0?mm. Absolute dose in the point of measurement was obtained with an ionization chamber calibrated to dose in water. From the collected data, detector sensitivities were obtained as function of the beam kVp and additional filtration. Using Monte Carlo simulations relative scintillator sensitivities were computed. For some of the scintillators these sensitivities show strong energy-dependence for beam average energy below 35?keV for each additional filtration but fair constancy above. One of the scintillators (BC-404) has smaller energy-dependence at low photon average energy and could be considered a candidate for applications (like mammography) where beam energy has small span.

Peralta, Luis; Rêgo, Florbela

2014-08-01

357

A study of GPS ionospheric scintillations observed at Shenzhen  

NASA Astrophysics Data System (ADS)

Ionospheric scintillation variations are studied using GPS measurements at the low latitude station of Shenzhen (22.59°N, 113.97°E), situated under the northern crest of the equatorial anomaly region, from the Chinese Meridian Project. The results are presented for data collected during the current phase of rising solar activity (low to high solar activity) from December 2010 to April 2014. The results show that GPS scintillation events were largely a nighttime phenomenon during the whole observation period. Scintillation events mainly occurred along the inner edge of the northern crest of the equatorial anomaly in China. The occurrence of scintillations in different sectors of the sky was also investigated, and the results revealed that it is more likely for the scintillations to be observed in the west sector of the sky above Shenzhen. During the present period of study, a total number of 512 total electron content (TEC) depletions and 460 lock loss events were observed. In addition, both of these events are likely to increase during periods of high solar activity, especially because the strong scintillations are often simultaneously accompanied by TEC depletions and lock losses by GPS receivers.

Huang, Linfeng; Wang, Jinsong; Jiang, Yong; Chen, Zhou; Zhao, Kai

2014-12-01

358

Characterization of water-based liquid scintillator response to gammas and neutrons at varying scintillator-surfactant concentrations  

E-print Network

Large scale solar neutron and neutrino flux experiments require many tons of bulk liquid organic scintillator to take spectroscopic data of these energetic particles. However, material and chemical concerns make such ...

Chilton, Lauren (Lauren M.)

2012-01-01

359

Developing a Culturally Responsive Breast Cancer Screening Promotion with Native Hawaiian Women in Churches  

ERIC Educational Resources Information Center

This article presents findings from research to develop the promotional component of a breast cancer screening program for Native Hawaiian women associated with historically Hawaiian churches in medically underserved communities. The literature on adherence to health recommendations and health promotions marketing guided inquiry on screening…

Kaopua, Lana Sue

2008-01-01

360

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

PubMed

Megavoltage cone-beam computed tomography (MV CBCT) is a highly promising technique for providing volumetric patient position information in the radiation treatment room. Such information has the potential to greatly assist in registering the patient to the planned treatment position, helping to ensure accurate delivery of the high energy therapy beam to the tumor volume while sparing the surrounding normal tissues. Presently, CBCT systems using conventional MV active matrix flat-panel imagers (AMFPIs), which are commonly used in portal imaging, require a relatively large amount of dose to create images that are clinically useful. This is due to the fact that the phosphor screen detector employed in conventional MV AMFPIs utilizes only approximately 2% of the incident radiation (for a 6 MV x-ray spectrum). Fortunately, thick segmented scintillating detectors can overcome this limitation, and the first prototype imager has demonstrated highly promising performance for projection imaging at low doses. It is therefore of definite interest to examine the potential performance of such thick, segmented scintillating detectors for MV CBCT. In this study, Monte Carlo simulations of radiation energy deposition were used to examine reconstructed images of cylindrical CT contrast phantoms, embedded with tissue-equivalent objects. The phantoms were scanned at 6 MV using segmented detectors having various design parameters (i.e., detector thickness as well as scintillator and septal wall materials). Due to constraints imposed by the nature of this study, the size of the phantoms was limited to approximately 6 cm. For such phantoms, the simulation results suggest that a 40 mm thick, segmented CsI detector with low density septal walls can delineate electron density differences of approximately 2.3% and 1.3% at doses of 1.54 and 3.08 cGy, respectively. In addition, it was found that segmented detectors with greater thickness, higher density scintillator material, or lower density septal walls exhibit higher contrast-to-noise performance. Finally, the performance of various segmented detectors obtained at a relatively low dose (1.54 cGy) was compared with that of a phosphor screen similar to that employed in conventional MV AMFPIs. This comparison indicates that for a phosphor screen to achieve the same contrast-to-noise performance as the segmented detectors approximately 18 to 59 times more dose is required, depending on the configuration of the segmented detectors. PMID:18293571

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

2008-01-01

361

Progress on high-resolution tracking with scintillating fibres: a new detector based on capillaries filled with liquid scintillator  

NASA Astrophysics Data System (ADS)

The capabilities of a new detector based on capillaries filled with liquid scintillator have been investigated. Tests have been performed using various scintillating cocktails and readout systems. With the best combinations, and for light propagation over a few centimetres, the hit density is as high as 5 hits/mm. For propagation over distances greater than 10 cm, an attenuation length of ˜95 cm is measured. A spatial resolution of ? ? 12 ?m is obtained with capillaries of 20 ?m bore.

Adinolfi, M.; Angelini, C.; Cardini, A.; Cianfarani, C.; Da Vià, C.; Duane, A.; Fabre, J.-P.; Flaminio, V.; Frenkel, A.; Golovkin, S. V.; Gorin, A. M.; Gruwé, M.; Harrison, K.; Kanerva, M.; Kozarenko, E. N.; Kushnirenko, A. E.; Martellotti, G.; McEwen, J. G.; Morrison, D. R. O.; Penso, G.; Peresypkin, A. I.; Roda, C.; Websdale, D. M.; Wilquet, G.; Zaichenko, A. A.

1992-05-01

362

COATING ALTERNATIVES GUIDE (CAGE) USER'S GUIDE  

EPA Science Inventory

The guide provides instructions for using the Coating Alternatives GuidE (CAGE) software program, version 1.0. It assumes that the user is familiar with the fundamentals of operating an IBM-compatible personal computer (PC) under the Microsoft disk operating system (MS-DOS). CAGE...

363

Behavioral economics: "nudging" underserved populations to be screened for cancer.  

PubMed

Persistent disparities in cancer screening by race/ethnicity and socioeconomic status require innovative prevention tools and techniques. Behavioral economics provides tools to potentially reduce disparities by informing strategies and systems to increase prevention of breast, cervical, and colorectal cancers. With an emphasis on the predictable, but sometimes flawed, mental shortcuts (heuristics) people use to make decisions, behavioral economics offers insights that practitioners can use to enhance evidence-based cancer screening interventions that rely on judgments about the probability of developing and detecting cancer, decisions about competing screening options, and the optimal presentation of complex choices (choice architecture). In the area of judgment, we describe ways practitioners can use the availability and representativeness of heuristics and the tendency toward unrealistic optimism to increase perceptions of risk and highlight benefits of screening. We describe how several behavioral economic principles involved in decision-making can influence screening attitudes, including how framing and context effects can be manipulated to highlight personally salient features of cancer screening tests. Finally, we offer suggestions about ways practitioners can apply principles related to choice architecture to health care systems in which cancer screening takes place. These recommendations include the use of incentives to increase screening, introduction of default options, appropriate feedback throughout the decision-making and behavior completion process, and clear presentation of complex choices, particularly in the context of colorectal cancer screening. We conclude by noting gaps in knowledge and propose future research questions to guide this promising area of research and practice. PMID:25590600

Purnell, Jason Q; Thompson, Tess; Kreuter, Matthew W; McBride, Timothy D

2015-01-01

364

Behavioral Economics: “Nudging” Underserved Populations to Be Screened for Cancer  

PubMed Central

Persistent disparities in cancer screening by race/ethnicity and socioeconomic status require innovative prevention tools and techniques. Behavioral economics provides tools to potentially reduce disparities by informing strategies and systems to increase prevention of breast, cervical, and colorectal cancers. With an emphasis on the predictable, but sometimes flawed, mental shortcuts (heuristics) people use to make decisions, behavioral economics offers insights that practitioners can use to enhance evidence-based cancer screening interventions that rely on judgments about the probability of developing and detecting cancer, decisions about competing screening options, and the optimal presentation of complex choices (choice architecture). In the area of judgment, we describe ways practitioners can use the availability and representativeness of heuristics and the tendency toward unrealistic optimism to increase perceptions of risk and highlight benefits of screening. We describe how several behavioral economic principles involved in decision-making can influence screening attitudes, including how framing and context effects can be manipulated to highlight personally salient features of cancer screening tests. Finally, we offer suggestions about ways practitioners can apply principles related to choice architecture to health care systems in which cancer screening takes place. These recommendations include the use of incentives to increase screening, introduction of default options, appropriate feedback throughout the decision-making and behavior completion process, and clear presentation of complex choices, particularly in the context of colorectal cancer screening. We conclude by noting gaps in knowledge and propose future research questions to guide this promising area of research and practice. PMID:25590600

Thompson, Tess; Kreuter, Matthew W.; McBride, Timothy D.

2015-01-01

365

ScreenFlow  

NSDL National Science Digital Library

Capturing images and screen shots can be tricky, and it's nice to hear about new applications that can help out with such tasks. ScreenFlow allows users to create screen recordings and it also includes an array of editing options. Visitors should note that this is a trial version, and that the full-featured version costs $99. This version is compatible with computers running Mac OS X 10.5 Leopard.

2008-01-01

366

Scintillating LXe/LKr electromagnetic calorimeter  

SciTech Connect

A scintillating LXe/LKr electromagnetic calorimeter has been built at the ITEP and tested at the BATES (MIT) accelerator. The detector consists of a PMT matrix and 45 light collecting cells made of aluminized Mylar partially covered with p-terphenyl as a wavelength-shifter (WLS). Each pyramidal cell has (2.1 x 2.1) x 40 x (4.15 x 4.15) cm dimensions and is viewed by an FEU-85 glass-window photomultiplier. The detector has been exposed to the 106--348 MeV electron beam. The energy resolution is {sigma}{sub E}/E {approx_equal} 5%/{radical}E at 100--350 MeV range in LXe; the coordinate resolution is {sigma}{sub X} {approx_equal} 0.7 cm; the time resolution is {sigma}{sub {tau}} {approx_equal} 0.6 ns for a single cell. Possible ways to improve energy resolution are discussed.

Akimov, D.Yu.; Bolozdynya, A.J.; Churakov, D.L. [ITEP, Moscow (Russian Federation)] [and others] [ITEP, Moscow (Russian Federation); and others

1995-12-01

367

Excitonic effects in oxyhalide scintillating host compounds  

NASA Astrophysics Data System (ADS)

Ab-initio calculations based on density functional theory have been performed to study the electronic, optical, mechanical, and vibrational properties of scintillator host compounds YOX (X = F, Cl, Br, and I). Semiempirical dispersion correction schemes are used to find the effect of van der Waals forces on these layered compounds and we found this effect to be negligible except for YOBr. Calculations of phonons and elastic constants showed that all the compounds studied here are both dynamically and mechanically stable. YOF and YOI are found to be indirect band gap insulators while YOCl and YOBr are direct band gap insulators. The band gap is found to decrease as we move from fluorine to iodine, while the calculated refractive index shows the opposite trend. As the band gap decreases on going down the periodic table from YOF to YOI, the luminescence increases. The excitonic binding energy calculated, within the effective mass approximation, is found to be more for YOF than the remaining compounds, suggesting that the excitonic effect to be more in YOF than the other compounds. The optical properties are calculated within the Time-Dependent Density Functional Theory (TDDFT) and compared with results obtained within the random phase approximation. The TDDFT calculations, using the newly developed bootstrap exchange-correlation kernel, showed significant excitonic effects in all the compounds studied here.

Shwetha, G.; Kanchana, V.; Valsakumar, M. C.

2014-10-01

368

Progress with the MICE scintillating fiber trackers  

NASA Astrophysics Data System (ADS)

The International Muon Ionization Cooling Experiment (MICE) is a proof of principle demonstration of ionization cooling, for application in a future neutrino factory or muon collider. MICE is under construction at the Rutherford Appleton Laboratory (UK), where a dedicated beam line has been commissioned to transport particles produced inside the ISIS accelerator facility. The beam emittance will be measured using two scintillating fiber trackers on each side of the cooling channel, which will be mounted inside a 4 T solenoid. As particles pass through the tracker, their position will be measured at 5 stations, each of which provides a position resolution of less than 0.5 mm. The fiber trackers have been validated using cosmic ray tests, which have allowed the light yield to be found. In addition, a spare tracking station was exposed to the MICE beam, which has enabled the tracker readout to be integrated with the MICE DAQ for the first time. This test required the integration gate on the D0 AFE-IIt readout boards to be synchronized with particle arrival by using diagnostic signals from the ISIS accelerator.

Overton, Edward

2013-12-01

369

Excitonic effects in oxyhalide scintillating host compounds  

SciTech Connect

Ab-initio calculations based on density functional theory have been performed to study the electronic, optical, mechanical, and vibrational properties of scintillator host compounds YOX (X?=?F, Cl, Br, and I). Semiempirical dispersion correction schemes are used to find the effect of van der Waals forces on these layered compounds and we found this effect to be negligible except for YOBr. Calculations of phonons and elastic constants showed that all the compounds studied here are both dynamically and mechanically stable. YOF and YOI are found to be indirect band gap insulators while YOCl and YOBr are direct band gap insulators. The band gap is found to decrease as we move from fluorine to iodine, while the calculated refractive index shows the opposite trend. As the band gap decreases on going down the periodic table from YOF to YOI, the luminescence increases. The excitonic binding energy calculated, within the effective mass approximation, is found to be more for YOF than the remaining compounds, suggesting that the excitonic effect to be more in YOF than the other compounds. The optical properties are calculated within the Time-Dependent Density Functional Theory (TDDFT) and compared with results obtained within the random phase approximation. The TDDFT calculations, using the newly developed bootstrap exchange-correlation kernel, showed significant excitonic effects in all the compounds studied here.

Shwetha, G.; Kanchana, V., E-mail: kanchana@iith.ac.in [Department of Physics, Indian Institute of Technology Hyderabad, Ordnance Factory Estate, Yeddumailaram 502 205, Telangana (India); Valsakumar, M. C. [School of Engineering Sciences and Technology (SEST), University of Hyderabad, Prof. C. R. Rao Road, Gachibowli, Hyderabad 500 046, Telangana (India)

2014-10-07

370

Breast Screening Revisited  

PubMed Central

Breast screening is the medical screening of asymptomatic, apparently healthy women for breast lump in an attempt to achieve an earlier diagnosis. The assumption is that the early detection will improve outcomes. In western countries, breast screening programs have led to a significant reduction in mortality and improved prognosis of patients with breast cancer. However in India, although the number of breast cancer are on the rise there is no such organized program. This article emphasizes on the importance of breast screening and protocol to be followed in our country where it can have significant impact on the prognosis.

Agrawal, Alka; Tripathi, Prem; Sahu, Abhinav; Daftary, Jalpa

2014-01-01

371

Characterization of 4 × 4ch MPPC array in scintillation spectrometry  

NASA Astrophysics Data System (ADS)

The aim of this work is an evaluation of MPPC array characteristics in application for scintillation light readout in gamma-ray spectrometry. Hamamatsu MPPC array of 4 × 4 channels format and total area of 12 × 12 mm2 was used as a light readout device with CsI:Tl, BGO, LSO, LaBr3, NaI:Tl, CsI:Na, LaCl3, CaF2:Eu, and CdWO4 scintillators. The measurements presented in this work covered: measurements of the breakdown voltage for each channel of the MPPC array, selection of the optimum operating voltage, evaluation of the linearity range of MPPC response for each of the used crystals, measurements of the number of photoelectrons per MeV and measurements of the energy resolution for 661.6 keV ?-rays from 137Cs. The results of the energy resolution and number of photoelectrons obtained with the tested MPPC and nine scintillators were compared to those obtained for the same scintillators with XP2020Q and XP5212 PMTs. The energy resolution data for 661.6 keV ?-rays, obtained with 12 × 12 × 12 mm3 CsI:Tl, LSO and BGO scintillators coupled to the tested MPPC are equal to: 6.4%, 9.4% and 9.5%, respectively, and are close to the results obtained for the same scintillators coupled to the XP2020Q PMT (6.6%, 9.4% and 10.5%, respectively). The study showed that light readout by means of an MPPC array produces comparable or even slightly better (in the case of a proper match of the MPPC and the scintillator optical surface) results than the XP2020Q PMT readout.

Grodzicka, M.; Moszy?ski, M.; Szcz??niak, T.; Szaw?owski, M.; Baszak, J.

2013-09-01

372

A capability for monitoring effluent tritium with liquid scintillation/robotics  

SciTech Connect

Strong interest persists in developing real-time tritium effluent monitoring. At the Savannah River site, this interest was intensified following a release from a K reactor heat exchanger in December 1991. Follow-up research and development resulted in adapting a flow-through tritium monitor based on scintillation beads and developing a similar system that mixes liquid scintillant into the sample stream. The bead system has the advantage of consuming little scintillant material, while the liquid scintillation method affords much better sensitivity. This study examines a method based on liquid scintillation and robotics, which can provide sensitivity and scintillant requirements that are intermediate to the foregoing.

Winn, W.G. (Westinghouse Savannah River Co., Aiken, SC (United States))

1993-01-01

373

COVARIANCE ASSISTED SCREENING AND ESTIMATION  

PubMed Central

Consider a linear model Y = X ? + z, where X = Xn,p and z ~ N(0, In). The vector ? is unknown and it is of interest to separate its nonzero coordinates from the zero ones (i.e., variable selection). Motivated by examples in long-memory time series (Fan and Yao, 2003) and the change-point problem (Bhattacharya, 1994), we are primarily interested in the case where the Gram matrix G = X?X is non-sparse but sparsifiable by a finite order linear filter. We focus on the regime where signals are both rare and weak so that successful variable selection is very challenging but is still possible. We approach this problem by a new procedure called the Covariance Assisted Screening and Estimation (CASE). CASE first uses a linear filtering to reduce the original setting to a new regression model where the corresponding Gram (covariance) matrix is sparse. The new covariance matrix induces a sparse graph, which guides us to conduct multivariate screening without visiting all the submodels. By interacting with the signal sparsity, the graph enables us to decompose the original problem into many separated small-size subproblems (if only we know where they are!). Linear filtering also induces a so-called problem of information leakage, which can be overcome by the newly introduced patching technique. Together, these give rise to CASE, which is a two-stage Screen and Clean (Fan and Song, 2010; Wasserman and Roeder, 2009) procedure, where we first identify candidates of these submodels by patching and screening, and then re-examine each candidate to remove false positives. For any procedure ?? for variable selection, we measure the performance by the minimax Hamming distance between the sign vectors of ?? and ?. We show that in a broad class of situations where the Gram matrix is non-sparse but sparsifiable, CASE achieves the optimal rate of convergence. The results are successfully applied to long-memory time series and the change-point model. PMID:25541567

Ke, By Tracy; Jin, Jiashun; Fan, Jianqing

2014-01-01

374

Lung cancer screening.  

PubMed

The United States Preventive Services Task Force recommends lung cancer screening with low-dose computed tomography (LDCT) in adults of age 55 to 80 years who have a 30 pack-year smoking history and are currently smoking or have quit within the past 15 years. This recommendation is largely based on the findings of the National Lung Screening Trial. Both policy-level and clinical decision-making about LDCT screening must consider the potential benefits of screening (reduced mortality from lung cancer) and possible harms. Effective screening requires an appreciation that screening should be limited to individuals at high risk of death from lung cancer, and that the risk of harm related to false positive findings, overdiagnosis, and unnecessary invasive testing is real. A comprehensive understanding of these aspects of screening will inform appropriate implementation, with the objective that an evidence-based and systematic approach to screening will help to reduce the enormous mortality burden of lung cancer. PMID:25369325

Tanoue, Lynn T; Tanner, Nichole T; Gould, Michael K; Silvestri, Gerard A

2015-01-01

375

Screening for dementia in \\  

Microsoft Academic Search

Among elderly people who do not present with complaints of memory impairment, dementia is often missed by physicians, and time-consuming screening tests requiring expertise to administer and interpret are rarely done. Easily administered, reliable and cost effective dementia screening tests are needed for elderly individuals. The \\

Joan M. Swearer; David A. Drachman; Lynn Li; Kevin J. Kane; Brian Dessureau; Patricia Tabloski

2002-01-01

376

Screening for School Entry.  

ERIC Educational Resources Information Center

Screening programs are now widely used with children who are age-eligible for school entry. Screening is used to identify children who may be at risk of future difficulty in school (e.g., inability to meet academic expectations) and those who may have special needs in learning (e.g., extraordinary abilities and talents or handicapping conditions).…

Hills, Tynette Wilson

377

Scoliosis Screening in Schools.  

ERIC Educational Resources Information Center

The booklet outlines New York state school policy and procedures for screening students for scoliosis, lateral curvature of the spine. It is explained that screening is designed to discover spinal deformities early enough to prevent surgery. Planning aspects, including organizing a planning team for the school district, are discussed. Among…

New York State Education Dept., Albany. Div. of Pupil Personnel Services.

378

Film Screening and Conversation  

E-print Network

Film Screening and Conversation 2011 6-9pm Smithsonian Asian Paci c American Program Rasmuson Director John Sayles Film Run Time: 124 minutes Closest Metro: L'Enfant Plaza Related Traveling Exhibition, the Smithsonian Asian Pacific American Program presents a screening of the film Amigo and a conversation

Mathis, Wayne N.

379

Breast cancer screening.  

PubMed

Mammography remains the primary technique for breast cancer screening. Women with dense breast tissue may benefit from digital mammography and tomosynthesis, and women at high risk may benefit from magnetic resonance imaging. However, false-positive results are problematic. The North Carolina breast density law necessitates education about screening options for women with dense breasts. PMID:24663133

Freimanis, Rita I; Yacobozzi, Margaret

2014-01-01

380

AMG All Music Guide  

NSDL National Science Digital Library

The AMG All Music Guide website is designed to complement a line of books that provide extensive reviews of thousands of music recordings, organized by genre, such as blues, jazz, rock, and so on. This website is particularly helpful as it provides all of this material at no cost, and is relatively easy to navigate as well. Using the search box at the top of the screen visitors can look for various artists, albums, songs, styles, or labels. After returning results, visitors can browse through the material, and click on any number of available hyperlinks in order to make their way to related material, such as genre, related artists and the like. For example, if one were to search for Duke Ellington, the search would return a brief essay about his work, a complete list of his recordings (with reviews), as well as additional information, such as Billboard chart information, Grammy nominations, and artists who he influenced. The site is rounded out by a series of short essays on a plethora of musical styles, including garage rock, acoustic blues, and zydeco.

381

A scintillating fission detector for neutron flux measurements  

SciTech Connect

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

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

2010-01-01

382

The uniformity and imaging properties of some new ceramic scintillators  

NASA Astrophysics Data System (ADS)

Results are presented of investigations into the composition, uniformity and gamma-ray imaging performance of new ceramic scintillators with synthetic garnet structure. The ceramic scintillators were produced by a process that uses flame pyrolysis to make nanoparticles which are sintered into a ceramic and then compacted by hot isostatic compression into a transparent material. There is concern that the resulting ceramic scintillator might not have the uniformity of composition necessary for use in gamma-ray spectroscopy and gamma-ray imaging. The compositional uniformity of four samples of three ceramic scintillator types (GYGAG:Ce, GLuGAG:Ce and LuAG:Pr) was tested using an electron microprobe. It was found that all samples were uniform in elemental composition to the limit of sensitivity of the microprobe (few tenths of a percent atomic) over distance scales from ~ 1 cm to ~ 1 um. The light yield and energy resolution of all ceramic scintillator samples were mapped with a highly collimated 57Co source (122 keV) and performance was uniform at mapping scale of 0.25 mm. Good imaging performance with single gamma-ray photon detection was demonstrated for all samples using a BazookaSPECT system, and the imaging spatial resolution, measured as the FWHM of a LSF was 150 um.

Chac, George T. L.; Miller, Brian W.; Shah, Kanai; Baldoni, Gary; Domanik, Kenneth J.; Bora, Vaibhav; Cherepy, Nerine J.; Seeley, Zachary; Barber, H. Bradford

2012-10-01

383

Tests of Multibeam Scintillation Mitigation on Laser Uplinks  

NASA Technical Reports Server (NTRS)

A report presents additional details about parts of the program of research and development that is the topic of the immediately preceding article. The report emphasizes those aspects of the program that pertain to the use of multiple uplink laser beams in a ground-to-spacecraft optical communication system to reduce (relative to the case of a single uplink laser beam) the depth and frequency of occurrence of fades in the uplink signal received at the spacecraft. The underlying multibeam scintillation-mitigation concept was described in "Multiple-Beam Transmission for Optical Communication" (NPO-20384), NASA Tech Briefs, Vol. 22, No. 11 (November 1998), page 56. The report discusses the need for mitigating uplink scintillation; briefly describes the Optical Communications Telescope Laboratory and its role as the ground station in the research; summarizes prior experiments in uplink scintillation and multibeam mitigation of scintillation in ground-to-spacecraft laser communications; and describes key experiments planned to be performed in the next five years. The report then elaborates somewhat on the initial experiments, which are to be dedicated to understanding and perfecting the multibeam scintillation-mitigation strategy.

Wilson, Keith

2004-01-01

384

Measurement of ortho-positronium properties in liquid scintillators  

NASA Astrophysics Data System (ADS)

Pulse shape discrimination is a well-established technique for background rejection in liquid scintillator detectors. It is particularly effective in separating heavy particles from light particles, but not in distinguishing electrons from positrons. This inefficiency can be overtaken by exploiting the formation of ortho-positronium (o-Ps), which alters the time profile of light pulses induced by positrons. We characterized the o-Ps properties in the most commonly used liquid scintillators, i.e. PC, PXE, LAB, OIL and PC + PPO. In addition, we studied the effects of scintillator doping on the o-Ps properties for dopants used in neutrino-less double beta decay experiments (Nd and Te) and in anti-neutrino and neutron detection (Gd and Li respectively). We found that the o-Ps properties are similar in all the tested scintillators, with a lifetime around 3 ns and a formation probability of about 50%. This result indicates that an o-Ps-enhanced pulse shape discrimination can be applied in liquid scintillator detectors for neutrino and anti-neutrino detection and for neutrino-less double beta decay search.

Perasso, S.; Consolati, G.; Franco, D.; Jollet, C.; Meregaglia, A.; Tonazzo, A.; Yeh, M.

2014-03-01

385

Scintillation luminescence for high-pressure xenon gas  

NASA Astrophysics Data System (ADS)

Scintillation and ionization yields in xenon gas for 5.49MeV alpha-particles were measured in the range of pressure from 0.35 to 3.7MPa and the electric field strength (E) over the number density of xenon atoms (N), E/N from 0 to 5×10-18Vcm2. When our data are normalized at the data point measured by Saito et al., the number of scintillation photons is 2.3×105 while the number of ionization electrons is 2.0×105 at 2.6MPa and at 3.7×10-18Vcm2. The scintillation and ionization yields of xenon doped with 0.2% hydrogen, High-Pressure Xenon gas[H2-0.2%], at 2.6MPa was also measured. Scintillation yield of the Xe-H2 mixture gas is 80% as high as that of pure xenon. It is found that the scintillation yield is luminous enough to generate a trigger pulse of the high-pressure xenon time projection chamber, which is expected as a promising MeV Compton gamma-ray camera.

Kobayashi, S.; Hasebe, N.; Igarashi, T.; Kobayashi, M.-N.; Miyachi, T.; Miyajima, M.; Okada, H.; Okudaira, O.; Tezuka, C.; Yokoyama, E.; Doke, T.; Shibamura, E.; Dmitrenko, V. V.; Ulin, S. E.; Vlasik, K. F.

2004-09-01

386

A Forecasting Ionospheric Real-time Scintillation Tool (FIRST)  

NASA Astrophysics Data System (ADS)

Transionospheric radio waves propagating through an irregular ionosphere with plasma depletions, or "bubbles," are subject to sporadic enhancement and fading commonly referred to as scintillation. Knowledge of the current ionospheric condition allows system operators to distinguish between compromises due to the radio environment and system induced failures, while a forecast of the same provides the opportunity for operators to take appropriate actions to mitigate the effects and optimize service. This paper describes a technique that uses the readily accessible ionospheric characteristic h'F from ground-based ionospheric sounder data near the geomagnetic equator to forecast the occurrence or nonoccurrence of low-latitude scintillation activity in VHF/UHF bands. We illustrate the development of the Forecasting Ionospheric Real-time Scintillation Tool and its real-time capability for forecasting scintillation activity. Finally, we have found that there exists a threshold in the h'F value at 1930 LT that corresponds to the onset of scintillation activity in the Peruvian longitude sector, which is found to decrease with decreasing F10.7 cm fluxes in a linear manner.

Redmon, Robert J.; Anderson, David; Caton, Ron; Bullett, Terence

2010-12-01

387

Guide to treatment technology for contaminated soils  

SciTech Connect

This document is a guide for the screening of alternative treatment technologies for contaminated soils. The contents of this guide are organized into: 1. Introduction, II. Utilizing the table, III. Tables: Contamination Versus Technology, TV. Contaminant Waste Groups, and V. References. The four Contaminations Versus Technology tables are designed to identify the effectiveness and/or potential applicability of technologies to some or all compounds within specific waste groups. The tables also present limitations and special use considerations for the particular treatment technology. The phase of development of the technology is also included in the table. The phases are: Available, Innovative, and Emerging technologies. The technologies presented in this guide are organized according to the method of treatment. The four (4) treatment methods are Biological, Solidification/Stabilization, Thermal, and Chemical/Physical Treatment. There are several processing methods; some are well developed and proven, and others are in the development stage.

Tran, H.; Aylward, R.

1992-08-04

388

Sensors Based on Spectroscopy of Guided Waves  

NASA Astrophysics Data System (ADS)

The last two decades have witnessed remarkable progress in the develpment of affinity biosensors and their applications in areas such as environmental protection, biotechnology, medical diagnostics, drug screening, food safety, and security. An affinity biosensor consists of a transducer and a biological recognition element which is able to interact with a selected analyte. Various optical methods have been exploited in biosensors including fluorescence spectroscopy, interferometry (reflectometric white light interferometry, modal interferometry in optical waveguide structures), and spectroscopy of guided modes of optical waveguides. Optical biosensors based on spectroscopy of guided modes of optical waveguides - grating coupler, resonant mirror, and surface plasmon resonance (SPR) - rely on the measurement of binding-induced refractive index changes and thus are label-free technologies. This paper reviews fundamentals of optical sensors based on spectroscopy of guided modes of optical waveguides and their applications.

Homola, Ji?í

389

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

SciTech Connect

Purpose: Positron emission tomography (PET) detectors that use a dual-ended-scintillator readout to measure depth-of-interaction (DOI) must have an accurate DOI function to provide the relationship between DOI and signal ratios to be used for detector calibration and recalibration. In a previous study, the authors used a novel and simple method to accurately and quickly measure DOI function by irradiating the detector with an external uniform flood source; however, as a practical concern, implementing external uniform flood sources in an assembled PET system is technically challenging and expensive. In the current study, therefore, the authors investigated whether the same method could be used to acquire DOI function from scintillator-generated (i.e., internal) radiation. The authors also developed a method for calibrating the energy scale necessary to select the events within the desired energy window. Methods: The authors measured the DOI function of a PET detector with lutetium yttrium orthosilicate (LYSO) scintillators. Radiation events originating from the scintillators' internal Lu-176 beta decay were used to measure DOI functions which were then compared with those measured from both an external uniform flood source and an electronically collimated external point source. The authors conducted these studies with several scintillators of differing geometries (1.5 x 1.5 and 2.0 x 2.0 mm{sup 2} cross-section area and 20, 30, and 40 mm length) and various surface finishes (mirror-finishing, saw-cut rough, and other finishes in between), and in a prototype array. Results: All measured results using internal and external radiation sources showed excellent agreement in DOI function measurement. The mean difference among DOI values for all scintillators measured from internal and external radiation sources was less than 1.0 mm for different scintillator geometries and various surface finishes. Conclusions: The internal radioactivity of LYSO scintillators can be used to accurately measure DOI function in PET detectors, regardless of scintillator geometry or surface finish. Because an external radiation source is not needed, this method of DOI function measurement can be practically applied to individual PET detectors as well as assembled systems.

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

2012-02-15

390

Photoelectron anticorrelations and sub-Poisson statistics in scintillation detectors  

PubMed Central

The performance of scintillation detectors for x rays and gamma rays is limited fundamentally by the statistics of the scintillation light and the resulting photoelectrons. This paper presents a new experimental approach to studying these statistics by observing correlations in the signals from two photodetectors. It is shown that the Fano factors (ratios of variance to mean), both for the number the photoelectrons produced on the photocathode of the photomultiplier and for the underlying number of scintillation photons, can be deduced from these correlations. For LaBr3(Ce) and 662 keV gamma rays, the photopeak signals obtained by photomultipliers on opposite faces of a thin sample are negatively correlated, and the Fano factor for the photoelectrons is significantly less than one. The inferred Fano factor for the optical photons is very small, indistinguishable from zero within experimental error. PMID:20725609

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

2010-01-01

391

Scintillation Properties of Eu2+-Activated Barium Fluoroiodide  

SciTech Connect

The scintillation properties of powders and single-crystals of BaFI doped with Eu2+ are presented. Single crystals were grown by the vertical Bridgman technique. Under optical and X-ray excitation, the samples exhibit a narrow E2+ 5d-4f transition emission centered at 405 nm. The scintillation light output is estimated to be 55,000+-5,000 photons/MeV at 662 keV with 85percent of the light decaying within 600 ns. An energyresolution of 8.5percent full width at half maximum (FWHM) has been achieved using this scintillator for 662 keV excitation (137Cs source) at room temperature.

Gundiah, Gautam; Bourret-Courchesne, Edith; Bizarri, Gregory; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew; Moses, William W.; Derenzo, Stephen E.

2009-11-18

392

Radiation-damage measurements on PVT-based plastic scintillators  

NASA Astrophysics Data System (ADS)

Samples of PVT-based plastic scintillators produced by Nuclear Enterprise Technology Ltd. (NET) were irradiated up to 9 kGy, both with a gamma source and within a typical accelerator radiation field (CERN PS ACOL Irradiation Facility). The consequent reduction of scintillating efficiency and light transmission were measured, as well as subsequent recovery, over a period of several months. The main results show that irradiation affects more the light transmission than the light emission. The radiation type does not affect either the amount of transmission reduction or the recovery. Observations were also made by means of polarized light. Non-uniformities and internal stresses were observed in scintillator bulks which were polymerized too quickly. These defects influence the light transmission.

Ilie, S.; Schönbacher, H.; Tavlet, M.

1993-05-01

393

Pulse shape discrimination with lithium-containing organic scintillators  

NASA Astrophysics Data System (ADS)

6Li-containing organic scintillators have been prepared and characterized as a new type of transparent, single-phase materials with pulse shape discrimination (PSD) properties for simultaneous detection of thermal and fast neutrons discriminated from gamma radiation. Tests conducted with recently developed PSD-capable plastic scintillators showed that incorporation of 6Li into the aromatic matrix with fast-neutron/gamma discrimination properties offers the additional sensitivity to thermal neutrons, substantially increasing efficiency and the energy range of neutron detection. Comparative analyses of 6Li-loaded plastic, liquid and single crystal organic scintillators provide evidence that, in addition to neutron/gamma discrimination, these novel materials have the ability for discrimination between the signatures of fast and thermal neutrons.

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

2013-11-01

394

Scintillation Response of Liquid Xenon to Low Energy Nuclear Recoils  

E-print Network

Liquid Xenon (LXe) is expected to be an excellent target and detector medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). Knowledge of LXe ionization and scintillation response to low energy nuclear recoils expected from the scattering of WIMPs by Xe nuclei is important for determining the sensitivity of LXe direct detection experiments. Here we report on new measurements of the scintillation yield of Xe recoils with kinetic energy as low as 10 keV. The dependence of the scintillation yield on applied electric field was also measured in the range of 0 to 4 kV/cm. Results are in good agreement with recent theoretical predictions that take into account the effect of biexcitonic collisions in addition to the nuclear quenching effect.

Aprile, E; Majewski, P; Yamashita, M; Hasty, R; Manzur, A; McKinsey, D N

2005-01-01

395

Avalanche Photodiode for liquid xenon scintillation: quantum efficiency and gain  

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

396

Lanthanum Chloride Scintillator for X-ray Detection  

NASA Astrophysics Data System (ADS)

In this presentation we describe the testing of a new cerium doped Lanthanum Chloride crystal (LaCl3:Ce), which makes an excellent scintillation material for X-ray counting applications. Detailed measurements were taken to determine the properties of the scintillator over an energy range of 5 to 60KeV; the results demonstrate that, when used with an appropriate PMT, the crystal sustains high count rates, minimal dead time and good energy resolution. For example an energy resolution of 35% (FWHM) was achieved at 22KeV and count rates of up to 1MHz are possible without dead-time correction. A comparison of LaCl3:Ce with two conventional scintillation materials, YAP:Ce and NaI(Tl) is also presented, which shows that that LaCl3:Ce offers a good balance of performance parameters for X-ray experiments.

Martin, T.; Allier, C.; Bernard, F.

2007-01-01

397

Scintillation Response of Liquid Xenon to Low Energy Nuclear Recoils  

E-print Network

Liquid Xenon (LXe) is expected to be an excellent target and detector medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). Knowledge of LXe ionization and scintillation response to low energy nuclear recoils expected from the scattering of WIMPs by Xe nuclei is important for determining the sensitivity of LXe direct detection experiments. Here we report on new measurements of the scintillation yield of Xe recoils with kinetic energy as low as 10 keV. The dependence of the scintillation yield on applied electric field was also measured in the range of 0 to 4 kV/cm. Results are in good agreement with recent theoretical predictions that take into account the effect of biexcitonic collisions in addition to the nuclear quenching effect.

E. Aprile; K. L. Giboni; P. Majewski; K. Ni; M. Yamashita; R. Hasty; A. Manzur; D. N. McKinsey

2005-03-29

398

Recent observations of equatorial and high latitude scintillations  

NASA Astrophysics Data System (ADS)

At equatorial latitudes, combined airborne and ground measurements of radar backscatter, electron density profiles, scintillations, airglow at 6300 A, and total electron content yielded data on the development and decay of the irregularity patches containing the hundred meter irregularities responsible for amplitude and phase scintillation. The use of airglow measurements from aircraft allowed the form of the patch to be deduced. At auroral latitudes, sheets of irregularities were observed at Poker Flat, Alaska and at Goose Bay, Labrador using phase fluctuations of the WIDEBAND signals. WIDEBAND phase and amplitude deviations when correlated with DMSP photographs show intense activity over diffuse and discrete aurora. The increase of intensity of scintillation activity at equatorial and polar latitudes was noted during 1979 and 1980 when very high solar flux levels were recorded. These increases take place even under quiet magnetic conditions when solar flux is high and take place during the increased number of magnetic storms.

Aarons, J.; Whitney, H. E.

1980-08-01

399

Scintillating bolometers for fast neutron spectroscopy in rare events searches  

NASA Astrophysics Data System (ADS)

Neutrons are a relevant background in rare events physics. Detectors based on fast neutron-induced nuclear reactions are commonly used for fast neutron spectroscopy. In this subject, scintillating bolometers provide an excellent energy resolution and particle discrimination by the simultaneous measurement of the heat and emitted light. Our group has constructed several 6Li and 10B based massive scintillating bolometers (LiF, Li6Eu(BO3)3, Li6Gd(BO3)3), with energy resolutions ranging from 16 to 200 keV. First results of a 32 gr 6LiF scintillating bolometer enriched at 95% in 6Li operated at 20 mK are presented. The use of this material in a multi-target cryogenic dark matter experiment, like EURECA, would allow monitoring the incident neutron flux in the detector during the data-taking.

Martínez, M.; Coron, N.; Ginestra, C.; Gironnet, J.; Gressier, V.; Leblanc, J.; de Marcillac, P.; Redon, T.; Di Stefano, P.; Torres, L.; Veber, P.; Velazquez, M.; Viraphong, O.

2012-07-01

400

Development of Scintillating Bolometers for Dark Matter Searches  

NASA Astrophysics Data System (ADS)

Scintillating bolometers, in which the simultaneous detection of light and heat allows to discriminate the nature of the interacting particle, are one of the most promising detectors for Dark Matter (DM) searches. One main advantage is the wide range of materials that can be used as target, that could provide a key for WIMP identification. The EURECA (European Underground Rare Event Calorimeter Array) project aims to install 1 ton of cryogenic detectors (Ge and solid state scintillators) to explore the spin independent (SI) scalar cross sections down to the 10-46 cm2 region. In this frame, the ROSEBUD collaboration is developing low temperature scintillating materials to be installed at the Canfranc Underground Laboratory. Work on 6Li and 10B based targets, that could allow to monitor the thermal and fast neutron flux within the experiments, is also presented.

Martínez, M.; Cuesta, C.; García, E.; Ginestra, C.; de Solórzano, A. Ortiz; Ortigoza, Y.; Pobes, C.; Puimedón, J.; Rolón, T.; Sarsa, M. L.; Villar, J. A.; Coron, N.; Gironnet, J.; Leblanc, J.; de Marcillac, P.; Redon, T.; Torres, L.; Veber, P.; Velázquez, M.

401

Minimum Bias Trigger Scintillators in ATLAS Run II  

NASA Astrophysics Data System (ADS)

The Minimum Bias Trigger Scintillators (MBTS) delivered the primary triggers for selecting events from real LHC collisions with the smallest bias for the low luminosity LHC RunI fills from 2009-2013 (proton-proton, lead-lead and lead-proton collisions). Similarly, for the next RunII of LHC (2015-2018) MBTS will provide key ingredients for the first physics measurements at larger LHC collisions energy (charge multiplicity, proton-proton cross section, rapidity gap measurements, ... ) and in general for low luminosity LHC fills. After more than 25 fb-1 of proton-proton collisions delivered during RunI, MBTS detectors have been substantially upgraded in preparation of RunII. The upgrade strategy is presented including the scintillator replacement, the modified read out scheme, the optical measurements on RunI scintillators assessing the degradation due to the dose received.

Sidoti, A.

2014-10-01

402

Quenching correction for volumetric scintillation dosimetry of proton beams  

PubMed Central

Purpose Volumetric scintillation dosimetry has the potential to provide fast, high-resolution, three-dimensional radiation dosimetry. However, scintillators exhibit a nonlinear response at the high linear energy transfer (LET) values characteristic of proton Bragg peaks. The purpose of this study was to develop a quenching correction method for volumetric scintillation dosimetry of proton beams. Methods Scintillation light from a miniature liquid scintillator detector was measured along the central axis of a 161.6-MeV proton pencil beam. Three-dimensional dose and LET distributions were calculated for 85.6-, 100.9-, 144.9-, and 161.6-MeV beams using a validated Monte Carlo model. LET values were also calculated using an analytical formula. A least-squares fit to the data established the empirical parameters of a quenching correction model. The light distribution in a tank of liquid scintillator was measured with a CCD camera at all four beam energies. The quenching model and LET data were used to correct the measured light distribution. Results The calculated and measured Bragg peak heights agreed within ±3% for all energies except 85.6 MeV, where the agreement was within ±10%. The quality of the quenching correction was poorer for sharp low-energy Bragg peaks because of blurring and detector size effects. The corrections performed using analytical LET values resulted in doses within 1% of those obtained using Monte Carlo LET values. Conclusion The proposed method can correct for quenching with sufficient accuracy for dosimetric purposes. The required LET values may be computed effectively using Monte Carlo or analytical methods. Future detectors should improve blurring correction methods and optimize the pixel size to improve accuracy for low-energy Bragg peaks. PMID:23257200

Robertson, Daniel; Mirkovic, Dragan; Sahoo, Narayan; Beddar, Sam

2013-01-01

403

Smaller, Lower-Power Fast-Neutron Scintillation Detectors  

NASA Technical Reports Server (NTRS)

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

Patel, Jagdish; Blaes, Brent

2008-01-01

404

A prototype scintillation dosimeter customized for small and dynamic megavoltage radiation fields.  

PubMed

A prototype plastic scintillation dosimeter has been developed with a small sensitive volume, rapid response and good dosimetric performance. The novelty of this design is the use of an air core light guide to transport the scintillation signal out of the primary radiation field. The significance of this innovation is that it eliminates the Cerenkov background signal that is generated in conventional optical fibres. The dosimeter performance was compared to existing commercial dosimeters in 6 MV and 18 MV photon beams and 6 MeV and 20 MeV electron beams, in both static and dynamic fields. The dosimeter was tested in small static fields and in dynamically delivered fields where the detector volume is shielded, while the stem is irradiated. The depth dose measurements for the photon beams agreed with ionization chamber measurements to within 1.6%, except in the build-up region due to positional uncertainty. For the 6 MeV and 20 MeV electron beams, the percentage depth dose measurements agreed with the ionization chamber measurements to within 3.6% and 4.5%, respectively. For field sizes of 1 cm x 1 cm and greater, the air core dosimeter readings agreed with diamond detector readings to within 1.2%. The air core dosimeter was accurate in dynamically delivered fields and had no measurable stem effect. The air core dosimeter was accurate over a range of field sizes, energies and dose rates, confirming that it is a sensitive and accurate dosimeter with high spatial resolution suitable for use in megavoltage photon and electron beams. PMID:20107251

Lambert, Jamil; Yin, Yongbai; McKenzie, David R; Law, Susan H; Ralston, Anna; Suchowerska, Natalka

2010-02-21

405

Properties of an imaging gas scintillation proportional counter  

NASA Technical Reports Server (NTRS)

An instrument which combines the improved energy resolution offered by the gas scintillation proportional counter (GSPC) with the submillimeter imaging capabilities of the multiwire proportional counter (MWPC) is described. The imaging gas scintillation proportional counter detects the centroid of the UV light excited by X-ray photons interacting in the noble gas of the GSPC with a UV sensitive gas in the MWPC. The prototype counter yields a measured performance of 9% (FWHM) energy resolution and 0.9 mm (FWHM) spatial resolution at 6 keV. Further design refinements should achieve 18% (FWHM) energy resolution and 0.6 mm (FWHM) spatial resolution at 1 keV.

Ku, W. H.-M.; Hailey, C. J.

1981-01-01

406

Polystyrene-based scintillator with pulse-shape discrimination capability  

NASA Astrophysics Data System (ADS)

Polystyrene-based scintillators with 2-phenyl-5-(4-tert-butylephenyl)-1,3,4-oxadiazole (tert-BuPPD) or 2,5-di-(3-methylphenyl)-1,3,4 oxadiazole (m-DMePPD) are proposed for pulse-shape n/?-discrimination. These scintillators have improved mechanical properties, long operational time and high n/? discrimination parameter - figure of merit (1.49 and 1.81 in a wide energy region), so they can be used as detectors of fast neutrons in the presence of gamma radiation background.

Zhmurin, P. N.; Lebedev, V. N.; Titskaya, V. D.; Adadurov, A. F.; Elyseev, D. A.; Pereymak, V. N.

2014-10-01

407

Long-term control of solar activity on equatorial scintillations  

NASA Astrophysics Data System (ADS)

The Sun has a tremendous influence on the Earth's upper atmosphere. It is not only a source of ionizing radiation but also produces severe disturbances like geomagnetic storms. The 11-year cycle in the variation of behavior and energy output of the Sun influences the generation of equatorial F-region irregularities, which produce scintillations of satellite signals. The phenomenon of scintillations particularly in the L-band has received considerable attention in recent years because of its detrimental effects on communication and navigational systems like GPS. Amplitude scintillations induce signal fading and when the depth of fading exceeds the fade margin of a receiving system, message errors in satellite communication systems are introduced. In GPS, amplitude scintillation may cause degradation of position fixing by standalone GPS receivers, data loss and cycle slips. Severe phase scintillations may stress phase-locked loops in GPS receivers and give rise to loss of phase lock. Scintillation is not a transient phenomenon like the geomagnetic storms but is prevalent mostly during magnetically quiet periods in the pre-midnight hours of equinoctial months of high sunspot number years for a station like Calcutta located near the northern crest of the equatorial anomaly. Amplitude scintillations at L-band (1.5 GHz) and VHF (244 MHz) have been recorded at Calcutta (22.58oN, 88.38oE geographic; 32oN magnetic dip) for more than a solar cycle from geostationary satellites INMARSAT and FLEETSATCOM respectively. The signal-to-noise ratios of GPS L1 (1575.42 MHz) have also been recorded at the same station since 1994. This paper presents a study of L-band scintillations for nearly half a solar cycle (1996-2000) from Calcutta, which is located under the northern anomaly crest in the Indian longitude sector. The variations of occurrence with local time, season, solar and magnetic activity have been discussed to show that solar activity has a very prominent control over development of ionospheric F-region irregularities unlike the transient phenomenon associated with disturbed Sun and geomagnetic storms.

Dasgupta, A.

408

Silicon photomultiplier characterization with a scintillating bar detector  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

409

Scintillator Evaluation for High-Energy X-Ray Diagnostics  

SciTech Connect

This report presents results derived from a digital radiography study performed using x-rays from a 2.3 MeV, rod-pinch diode. Detailed is a parameter study of cerium-doped lutetium ortho-silicate (LSO) scintillator thickness, as it relates to system resolution and detection quantum efficiency (DQE). Additionally, the detection statistics of LSO were compared with that of CsI(Tl). As a result of this study we found the LSO scintillator with a thickness of 3 mm to yield the highest system DQE over the range of spatial frequencies from 0.75 to 2.5 mm{sup -1}.

S. S. Lutz; S. A. Baker

2001-09-01

410

A decametric wavelength radio telescope for interplanetary scintillation observations  

NASA Technical Reports Server (NTRS)

A phased array, electrically steerable radio telescope (with a total collecting area of 18 acres), constructed for the purpose of remotely sensing electron density irregularity structure in the solar wind, is presented. The radio telescope is able to locate, map, and track large scale features of the solar wind, such as streams and blast waves, by monitoring a large grid of natural radio sources subject to rapid intensity fluctuation (interplanetary scintillation) caused by the irregularity structure. Observations verify the performance of the array, the receiver, and the scintillation signal processing circuitry of the telescope.

Cronyn, W. M.; Shawhan, S. D.

1975-01-01

411

Relationship between microstructure and efficiency of scintillating glasses  

SciTech Connect

Prior work has shown that there is a correlation between trap densities and scintillation efficiency of cerium-activated, lithium-aluminosilicate glasses. Raman spectroscopy has strongly suggested that phase separation may be playing an important role in governing the scintillation efficiency. This study, relates the thermoluminescence glow-curve data and microstructural analysis for a compositional series. The thermoluminescence data provide information about the traps in the neighborhood of the activator (Ce{sup 3+}). The microscopy and crystallization of the glasses provide direct evidence of activator partitioning.

Bliss, M.; Craig, R.A.; Reeder, P.L.; Sunberg, D.S. [Pacific Northwest Lab., Richland, WA (United States); Weber, M.J. [Lawrence Livermore National Lab., CA (United States)

1994-04-01

412

Bismuth germanate as a potential scintillation detector in positron cameras.  

PubMed

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

Cho, Z H; Farukhi, M R

1977-08-01

413

Interventions to Promote Colorectal Cancer Screening: An Integrative Review  

PubMed Central

Behavior change interventions to promote colorectal cancer (CRC) screening have targeted people in community and primary care settings, health care providers, and health systems. Randomized controlled trials provide the strongest evidence of intervention efficacy. The purpose of this integrative review was to evaluate trials of CRC screening interventions published between 1997 and 2007 and to identify knowledge gaps and future directions for research. Thirty-three randomized trials that met inclusion criteria were evaluated using a modified version of the TREND criteria. Significant intervention effects were reported in six out of ten trials focused on increasing fecal occult blood testing, four of seven trials focused on sigmoidoscopy or colonoscopy completion, and nine of 16 focused on completion of any screening test. Several effective interventions to promote CRC screening were identified. Future trials need to use theory to guide interventions, examine moderators and mediators, consistently report results, and use comparable outcome measures. PMID:22261002

Rawl, Susan M.; Menon, Usha; Burness, Allison; Breslau, Erica S.

2012-01-01

414

A USERS GUIDE TO THE DISPLAY SCREEN EQUIPMENT REGULATIONS 1992  

E-print Network

, wrists, arms, neck and back. It is essential that if you have any pain or discomfort when using DSE............................................................................................ 3 4. PAIN AND DISCOMFORT the eye care scheme. 4. PAIN AND DISCOMFORT One of the risks associated with DSE use is work related upper

415

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

SciTech Connect

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 noise, expressed as the Swank factor. Our goal is to obtain results useful in optimizing screens for digital radiography systems. Experimental measurements from structured CsI samples were used to derive their screen optics properties, and the same methods can also be applied to powder screens. CsI screens, all of the same thickness but with different optical designs and manufacturing techniques, were obtained from Hamamatsu Photonics Corporation. The pulse height spectra (PHS) of the screens were measured at different x-ray energies. A theoretical model was developed for the light escape efficiency and a method for deriving light escape efficiency versus depth from experimental PHS measurements was implemented and applied to the CsI screens. The results showed that the light escape efficiency varies essentially linearly as a function of depth in the CsI samples, and that the magnitude of variation is relatively small, leading to a high Swank factor.

Lubinsky, A.R.; Zhao Wei; Ristic, Goran; Rowlands, J.A. [Department of Radiology, State University of New York at Stony Brook Stony Brook, New York 11794-8460 (United States); Imaging Research, Sunnybrook and Women's College Health Sciences Center Toronto, Ontario M4N 3M5 (Canada)

2006-05-15

416

Simulation of light transport in scintillators based on 3D characterization of crystal surfaces  

PubMed Central

In the development of positron emission tomography (PET) detectors, understanding and optimizing scintillator light collection is critical for achieving high performance, particularly when the design incorporates depth-of-interaction (DOI) encoding or time-of-flight information. Monte-Carlo simulations play an important role in guiding research in detector designs and popular software such as GATE now include models of light transport in scintillators. Although current simulation toolkits are able to provide accurate models of perfectly polished surfaces, they do not successfully predict light output for other surface finishes, for example those often used in DOI-encoding detectors. The lack of accuracy of those models mainly originates from a simplified description of rough surfaces as an ensemble of micro-facets determined by the distribution of their normal, typically a Gaussian distribution. The user can specify the standard deviation of this distribution, but this parameter does not provide a full description of the surface reflectance properties. We propose a different approach based on 3D measurements of the surface using atomic force microscopy (AFM). Polished and rough (unpolished) crystals were scanned to compute the surface reflectance properties. The angular distributions of reflectance and reflected rays were computed and stored in look-up tables (LUTs). The LUTs account for the effect of incidence angle and were integrated in a light transport model. Crystals of different sizes were simulated with and without reflector. The simulated maximum light output and the light output as a function of DOI showed very good agreement with experimental characterization of the crystals, indicating that our approach provides an accurate model of polished and rough surfaces and could be used to predict light collection in scintillators. This model is based on a true 3D representation of the surface, makes no assumption about the surface and provides insight on the optical behaviour of rough crystals that can play a critical role in optimizing the design of PET detectors. This approach is also compatible with existing simulation toolkits and next steps include the implementation in GATE. PMID:23475145

Cherry, Simon R.

2013-01-01

417

Simulation of light transport in scintillators based on 3D characterization of crystal surfaces.  

PubMed

In the development of positron emission tomography (PET) detectors, understanding and optimizing scintillator light collection is critical for achieving high performance, particularly when the design incorporates depth-of-interaction (DOI) encoding or time-of-flight information. Monte-Carlo simulations play an important role in guiding research in detector designs and popular software such as GATE now include models of light transport in scintillators. Although current simulation toolkits are able to provide accurate models of perfectly polished surfaces, they do not successfully predict light output for other surface finishes, for example those often used in DOI-encoding detectors. The lack of accuracy of those models mainly originates from a simplified description of rough surfaces as an ensemble of micro-facets determined by the distribution of their normal, typically a gaussian distribution. The user can specify the standard deviation of this distribution, but this parameter does not provide a full description of the surface reflectance properties. We propose a different approach based on 3D measurements of the surface using atomic force microscopy. Polished and rough (unpolished) crystals were scanned to compute the surface reflectance properties. The angular distributions of reflectance and reflected rays were computed and stored in look-up tables (LUTs). The LUTs account for the effect of incidence angle and were integrated in a light transport model. Crystals of different sizes were simulated with and without reflector. The simulated maximum light output and the light output as a function of DOI showed very good agreement with experimental characterization of the crystals, indicating that our approach provides an accurate model of polished and rough surfaces and could be used to predict light collection in scintillators. This model is based on a true 3D representation of the surface, makes no assumption about the surface and provides insight on the optical behaviour of rough crystals that can play a critical role in optimizing the design of PET detectors. This approach is also compatible with existing simulation toolkits and next steps include the implementation in GATE. PMID:23475145

Roncali, Emilie; Cherry, Simon R

2013-04-01

418

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

Microsoft Academic Search

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

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

2008-01-01

419

Supermirror neutron guide  

NASA Astrophysics Data System (ADS)

We present the results of investigations by grazing incidence neutron reflectometry of supermirrors NiC/Ti. Their effective critical angle is 1.9 times the critical angle of natural nickel. With these supermirrors, a curve neutron guide has been installed in the neutron guide hall of the ORPHEE reactor. This guide, called G5bis, has a radius of 155 m. The total flux measured at the guide exit is 1.22 109 n.cm-2.s-1. the layout and performances of the new guide are compared to the guide G5 and to a classical multichannel bender.

Ballot, Benedicte; Samuel, Francois J.; Farnoux, Bernard

1992-11-01

420

UK HealthCare Volunteer Orientation Guide 1 Updated August 2013  

E-print Network

UK HealthCare Volunteer Orientation Guide 1 Updated August 2013 UK HealthCare Volunteer Orientation Guide Welcome to the UK HealthCare Volunteer Program! Please review the following information and sign and drug screens for UK HealthCare volunteer positions. Please note that failing to successfully complete

MacAdam, Keith

421

Synthesis and scintillation properties of nano Gd 2O 3(Eu) scintillator for high resolution X-ray imaging applications  

NASA Astrophysics Data System (ADS)

Gd 2O 3:Eu scintillators with nano-crystalline structures were successfully synthesized through a precipitation method and subsequent calcination treatment as a converter for X-ray imaging detectors. In this work, a simple precipitation process was carried out using diethanolamine (DEA) as a precipitant to prepare nano-crystalline Eu-doped Gd 2O 3 powders. Scintillation properties such as luminescent spectra, light intensity and decay time were measured by varying the calcination temperature in heat-treatment of the synthesized powder. The sample prepared at 1200 °C calcination temperature showed the highest light intensity. And the scintillator emitted a strong red light at near 611 nm under photo- and X-ray luminescence for its potential X-ray imaging detector applications.

Cha, Bo Kyung; Lee, Seoung Jun; Muralidharan, P.; Kim, Jong Yul; Kim, Do Kyung; Lee, Dong Hyoung; Yun, Jong Il; Cho, Gyuseong

2010-07-01

422

Improved Prevention, Screening & Treatment  

Cancer.gov

Cancers develop through a complex interplay between genetic and environmental factors. By identifying and understanding this process, we can often develop preventive interventions or use tailored screening and treatment approaches for individuals at increased risk of developing cancer.

423

Human Papillomavirus (HPV) Screening  

MedlinePLUS

... Search The CDC Cancel Submit Search The CDC Human Papillomavirus (HPV) Note: Javascript is disabled or is ... Associated Cancers Gynecologic Cancers HPV Screening Share Compartir Human papillomavirus (HPV) causes genital warts and cancers, such ...

424

Endometrial Cancer Screening  

MedlinePLUS

... colon cancer , experts suggest yearly screening with transvaginal ultrasound, beginning as early as age 25. The use of tamoxifen to treat or prevent breast cancer increases the risk of endometrial cancer. TVU ...

425

Cervical Cancer Screening Programs  

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 Cervical Cancer: Mortality Rates | Organization

426

Cervical Cancer Screening Programs  

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 Cervical Cancer (Archived Tables): Home Organization

427

Colorectal Cancer Screenings (Coverage)  

MedlinePLUS

... you're 50 or older. Multi-target stool DNA test (like Cologuard™): Medicare covers this test once ... you pay nothing for a multi-target stool DNA test (like Cologuard™). If a screening colonoscopy or ...

428

Genetic Screening Debate  

MedlinePLUS Videos and Cool Tools

... the lower right-hand corner of the player. Genetic Screening Debate HealthDay November 13, 2014 Related MedlinePlus Pages Cancer Genetic Testing Transcript As genetic testing becomes more widely ...

429

What Is Carrier Screening?  

MedlinePLUS

... Financial Planning Who Should I Tell? Genetic Testing & Counseling Compensation for Genetic Testing Whole Genome Sequencing Screening vs. Testing What Is Genetic Counseling? Participating in Research Disease Research Patient Privacy Clinical ...

430

Methods of Fabricating Scintillators with Radioisotopes for Beta Battery Applications  

NASA Technical Reports Server (NTRS)

Technology has been developed for a class of self-contained, long-duration power sources called beta batteries, which harvest the energy contained in the radioactive emissions from beta decay isotopes. The new battery is a significant improvement over the conventional phosphor/solar cell concept for converting this energy in three ways. First, the thin phosphor is replaced with a thick scintillator that is transparent to its own emissions. By using a scintillator sufficiently thick to completely stop all the beta particles, efficiency is greatly improved. Second, since the energy of the beta particles is absorbed in the scintillator, the semiconductor photodetector is shielded from radiation damage that presently limits the performance and lifetime of traditional phosphor converters. Finally, instead of a thin film of beta-emitting material, the isotopes are incorporated into the entire volume of the thick scintillator crystal allowing more activity to be included in the converter without self-absorption. There is no chemical difference between radioactive and stable strontium beta emitters such as Sr-90, so the beta emitter can be uniformly distributed throughout a strontium based scintillator crystal. When beta emitter material is applied as a foil or thin film to the surface of a solar cell or even to the surface of a scintillator, much of the radiation escapes due to the geometry, and some is absorbed within the layer itself, leading to inefficient harvesting of the energy. In contrast, if the emitting atoms are incorporated within the scintillator, the geometry allows for the capture and efficient conversion of the energy of particles emitted in any direction. Any gamma rays associated with secondary decays or Bremsstrahlung photons may also be absorbed within the scintillator, and converted to lower energy photons, which will in turn be captured by the photocell or photodiode. Some energy will be lost in this two-stage conversion process (high-energy particle to low-energy photons to electric current). The geometric advantage partially offsets this as well, since the absorption depth of high-energy beta radiation is much larger than the depth of a p-n junction. Thus, in a p-n junction device, much of the radiation is absorbed far away from the junction, and the electron- hole pairs are not all effectively collected. In contrast, with a transparent scintillator the radiation can be converted to light in a larger volume, and all of the light can be collected in the active region of the photodiode. Finally, the new device is more practical because it can be used at much higher power levels without unduly shortening its lifetime. While the crystal structure of scintillators is also subject to radiation damage, their performance is far more tolerant of defects than that of semiconductor junctions. This allows the scintillator- based approach to use both higher energy isotopes and larger quantities of the isotopes. It is projected that this technology has the potential to produce a radioisotope battery with up to twice the efficiency of presently used systems.

Rensing, Noa M.; Squillante, Michael R.; Tieman, Timothy C.; Higgins, William; Shiriwadkar, Urmila

2013-01-01

431

Screening of Breast Cancer  

Microsoft Academic Search

\\u000a In the randomized controlled trials carried out in the late 1970s and the 1980s, mammographic screening was demonstrated to\\u000a have an impact in decreasing mortality from breast cancer. The evaluation of mammographic service screening programmes implemented\\u000a in several Western European countries in the late 1980s and the 1990s demonstrated that these programmes may have an even\\u000a higher effect on breast

Per Skaane

432

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

SciTech Connect

In this paper, 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 50mm range and compared with experimental results. It is shown that for a 2 inch photomultiplier d distances from 10 to 20mm, commonly used in the detector designs, represent a worst case situation.

Dos Santos, J.M.F.; Bento, A.C.S.S.M.; Conde, C.A.N. (Physics Dept., Univ. of Coimbra, P-3000, Coimbra (Portugal))

1992-08-01

433

Screening of solar cells  

NASA Technical Reports Server (NTRS)

Because solar cells in a production batch are not identical, screening is performed to obtain similar cells for aggregation into arrays. A common technique for screening is based on a single operating point of the I-V characteristic of the cell, usually the maximum power point. As a result, inferior cell matching may occur at the actual operating points. Screening solar cells based on the entire I-V characteristic will inherently result in more similar cells in the array. An array consisting of more similar cells is likely to have better overall characteristics and more predictable performance. Solar cell screening methods and cell ranking are discussed. The concept of a mean cell is defined as a cell 'best' representing all the cells in the production batch. The screening and ranking of all cells are performed with respect to the mean cell. The comparative results of different screening methods are illustrated on a batch of 50 silicon cells of the Space Station Freedom.

Appelbaum, J.; Chait, A.; Thompson, D. A.

1993-01-01

434

MDA ALS Caregiver's Guide  

MedlinePLUS

... emotional strategies for being an effective caregiver. The MDA ALS Caregiver’s Guide is meant to give guidance, ... strength and finding help. It frequently refers to MDA’s Everyday Life with ALS: A Practical Guide . Everyone ...

435

Fast scintillation counter preamplifier for the observation of Linsley effect  

Microsoft Academic Search

A fast preamplifier circuit has been designed and thoroughly tested for the purpose of observing the air shower arrival directions including the Linsley effect. The circuit intends to eliminate the time jitter due to variation of scintillation counter signal amplitudes. It assumes that the output signals from one counter system have the same rise time. On this basis, error arising

L. K. Ng

1985-01-01

436

Scintillation response of liquid xenon to low energy nuclear recoils  

NASA Astrophysics Data System (ADS)

Liquid Xenon (LXe) is expected to be an excellent target and detection medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). We have measured the scintillation efficiency of nuclear recoils with kinetic energy between 10.4 and 56.5 keV relative to that of 122 keV gamma rays from C57o. The scintillation yield of 56.5 keV recoils was also measured as a function of applied electric field, and compared to that of gamma rays and alpha particles. The Xe recoils were produced by elastic scattering of 2.4 MeV neutrons in liquid xenon at a variety of scattering angles. The relative scintillation efficiency is 0.130±0.024 and 0.227±0.016 for the lowest and highest energy recoils, respectively. This is about 15% less than the value predicted by Lindhard, based on nuclear quenching. Our results are in good agreement with more recent theoretical predictions that consider the additional reduction of scintillation yield due to biexcitonic collisions in LXe.

Aprile, E.; Giboni, K. L.; Majewski, P.; Ni, K.; Yamashita, M.; Hasty, R.; Manzur, A.; McKinsey, D. N.

2005-10-01

437

Liquid Xe scintillation calorimetry and Xe optical properties  

Microsoft Academic Search

The optical properties of LXe in the vacuum ultra violet (VUV), determining the performance of a scintillation calorimeter, are discussed in detail. The available data, measured in a wider spectral region from visible to UV light, and in a large range of Xe densities, from gas to liquid, are examined. It is shown that this information can be used for

A. Baldini; C. Bemporad; F. Cei; T. Doke; M. Grassi; T. Haruyama; S. Mihara; T. Mori; D. Nicolò; H. Nishiguchi; W. Ootani; K. Ozone; A. Papa; R. Pazzi; R. Sawada; F. Sergiampietri; G. Signorelli; S. Suzuki; K. Terasawa

2004-01-01

438

Scintillation efficiency of nuclear recoil in liquid xenon  

Microsoft Academic Search

We present the results of a test done with a Liquid Xenon (LXe) detector for “Dark Matter” search, exposed to a neutron beam to produce nuclear recoil events simulating those which would be generated by WIMP's elastic scattering. The aim of the experiment was to measure directly the scintillation efficiency of nuclear recoil. The nuclear recoil considered in the test

F. Arneodo; B. Baiboussinov; A. Badertscher; P. Benetti; E. Bernardini; A. Bettini; A Borio di Tiogliole; R. Brunetti; A. Bueno; E. Calligarich; M. Campanelli; C. Carpanese; D. Cavalli; F. Cavanna; P. Cennini; S. Centro; A. Cesana; D. Cline; I De Mitri; R. Dolfini; A. Ferrari; A Gigli Berzolari; C. Matthey; F. Mauri; D. Mazza; L. Mazzone; G. Meng; C. Montanari; G. Nurzia; S. Otwinowski; O. Palamara; D. Pascoli; A. Pepato; S. Petrera; L. Periale; G Piano Mortari; A. Piazzoli; P. Picchi; F. Pietropaolo; T. Rancati; A. Rappoldi; G. L Raselli; D. Rebuzzi; J. P Revo; J. Rico; M. Rossella; C. Rossi; A. Rubbia; C. Rubbia; P. Sala; D. Scannicchio; F. Sergiampietri; S. Suzuki; M. Terrani; W. Tian; S. Ventura; C. Vignoli; H. Wang; J. Woo; Z. Xu

2000-01-01

439

Scintillation e$ciency of nuclear recoil in liquid xenon  

Microsoft Academic Search

We present the results of a test done with a Liquid Xenon (LXe) detector for 'Dark Mattera search, exposed to a neutron beam to produce nuclear recoil events simulating those which would be generated by WIMP's elastic scattering. The aim of the experiment was to measure directly the scintillation e$ciency of nuclear recoil. The nuclear recoil considered in the test

F. Arneodo; B. Baiboussinov; A. Badertscher; P. Benetti; E. Bernardini; A. Bettini; A. Borio; R. Brunetti; A. Bueno; E. Calligarich; M. Campanelli; C. Carpanese; D. Cavalli; F. Cavanna; P. Cennini; A. Cesana; D. Cline; I. De Mitri; R. Dol; A. Ferrari; A. Gigli Berzolari; C. Matthey; F. Mauri; D. Mazza; L. Mazzone; G. Meng; C. Montanari; G. Nurzia; S. Otwinowski; O. Palamara; D. Pascoli; A. Pepato; S. Petrera; L. Periale; G. Piano Mortari; A. Piazzoli; P. Picchi; F. Pietropaolo; T. Rancati; A. Rappoldi; G. L. Raselli; D. Rebuzzi; J. Rico; M. Rossella; C. Rossi; A. Rubbia; C. Rubbia; P. Sala; D. Scannicchio; F. Sergiampietri; S. Suzuki; M. Terrani; W. Tian; S. Ventura; C. Vignoli; H. Wang; J. Woo; Z. Xu

440

Scintillation response of liquid xenon to low energy nuclear recoils  

SciTech Connect

Liquid Xenon (LXe) is expected to be an excellent target and detection medium to search for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). We have measured the scintillation efficiency of nuclear recoils with kinetic energy between 10.4 and 56.5 keV relative to that of 122 keV gamma rays from {sup 57}Co. The scintillation yield of 56.5 keV recoils was also measured as a function of applied electric field, and compared to that of gamma rays and alpha particles. The Xe recoils were produced by elastic scattering of 2.4 MeV neutrons in liquid xenon at a variety of scattering angles. The relative scintillation efficiency is 0.130{+-}0.024 and 0.227{+-}0.016 for the lowest and highest energy recoils, respectively. This is about 15% less than the value predicted by Lindhard, based on nuclear quenching. Our results are in good agreement with more recent theoretical predictions that consider the additional reduction of scintillation yield due to biexcitonic collisions in LXe.

Aprile, E.; Giboni, K.L.; Majewski, P.; Ni, K.; Yamashita, M.; Hasty, R.; Manzur, A.; McKinsey, D.N. [Physics Department and Astrophysics Laboratory, Columbia University, New York, New York 10027 (United States); Department of Physics, Yale University, P.O. Box 208120, New Haven, Connecticut 06520 (United States)

2005-10-01

441

Liquid xenon scintillation calorimetry and Xe optical properties  

Microsoft Academic Search

The optical properties of liquid xenon (LXe) in the vacuum ultra violet (VUV), determining the performance of a scintillation calorimeter, are discussed in detail. The available data, measured in a wider spectral region from visible to UV light, and in a large range of Xe densities, from gas to liquid, are examined. It is shown that this information can be

A. Baldini; C. Bemporad; F. Cei; T. Doke; M. Grassi; T. Haruyama; S. Mihara; T. Mori; D. Nicolo; H. Nishiguchi; W. Ootani; K. Ozone; A. Papa; R. Pazzi; R. Sawada; F. Sergiampietri; G. Signorelli; S. Suzuki; K. Terasawa

2006-01-01

442

MgWO 4-A new crystal scintillator  

NASA Astrophysics Data System (ADS)

Magnesium tungstate (MgWO 4) crystals of ~1 cm 3 volume were obtained for the first time using a flux growth technique. The crystal was subjected to comprehensive characterisation that included room-temperature measurements of the transmittance, X-ray luminescence spectra, afterglow under X-ray excitation, relative photoelectron output, energy resolution, non-proportionality of scintillation response to ?-quanta, response to ?-particles, and pulse shape for ?-quanta and ?-particles. The light output and decay kinetics of MgWO 4 were studied over the temperature range 7-305 K. Under X-ray excitation the crystal exhibits an intense luminescence band peaking at a wavelength of 470 nm; the intensity of afterglow after 20 ms is 0.035%. An energy resolution of 9.1% for 662 keV ?-quanta of 137Cs was measured with a small (?0.9 g) sample of the MgWO 4 crystal. The photoelectron output of the MgWO 4 crystal scintillator is 35% that of CdWO 4 and 27% that of NaI(Tl). The detector showed pulse-shape discrimination ability in measurements with ?-particles and ?-quanta, which enabled us to assess the radioactive contamination of the scintillator. The results of these studies demonstrate the prospect of this material for a variety of scintillation applications, including rare event searches.

Danevich, F. A.; Chernyak, D. M.; Dubovik, A. M.; Grinyov, B. V.; Henry, S.; Kraus, H.; Kudovbenko, V. M.; Mikhailik, V. B.; Nagornaya, L. L.; Podviyanuk, R. B.; Polischuk, O. G.; Tupitsyna, I. A.; Vostretsov, Yu. Ya.

2009-09-01

443

Direct determination of lead-210 by liquid-scintillation counting  

NASA Technical Reports Server (NTRS)

Soft betas, the internal conversion electrons, and unconverted gamma rays from lead-210 are efficiently detected in a liquid scintillation counting system with efficiency of 97 percent. The counter is interfaced with a multichannel pulse height analyzer. The spectra obtained is stored on paper tape and plotted on an x-y plotter.

Fairman, W. D.; Sedlet, J.

1969-01-01

444

High Resolution Scintillating Fiber Gamma Ray Detectors For Medical Imaging  

Microsoft Academic Search

High spatial and time resolution gamma ray detectors have been developed using plastic 'scintillating fibers coupled to position sensitive vacuum photomultipliers under development. These detectors can significantly improve the spatial resolution, time resolution, and efficiency of both SPECT and PET, extend the application of these technologies into new fields of medical research, and improve currently existing methods of medical diagnosis.

M. Atac; D. B. Cline; R. C. Chancy; E. J. Fenyves; G. Hademenos; P. P. Antich; M. D. Petroff

1990-01-01

445

Counterintuitive MCNPX Results for Scintillator Surface Roughness Effect  

SciTech Connect

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

None

2012-08-12

446

The time resolution of bismuth germanate scintillation detectors  

NASA Astrophysics Data System (ADS)

The time resolution of a bismuth germanate scintillation detector was measured as a function of ?-ray energy from 1 MeV to 24 MeV. The measured time resolution of the 60Co cascade is (2.1±0.2)ns. The time resolution improves at higher ?-ray energies and is (890±60) ps at around 20 MeV.

Wender, S. A.; Auchampaugh, G. F.; Hill, N. W.

1982-06-01

447

Scintillation-Induced Circular Polarization in Pulsars and Quasars  

E-print Network

We present a physical interpretation for the generation of circular polarization resulting from the propagation of radiation through a magnetized plasma in terms of a rotation measure gradient, or `Faraday wedges'. Criteria for the observability of scintillation-induced circular polarization are identified. Application of the theory to the circular polarization in pulsars and compact extragalactic sources is discussed.

J. -P. Macquart; D. B. Melrose

2000-07-28

448

DETERMINATION OF DIAMINE OXIDASE ACTIVITY BY LIQUID SCINTILLATION COUNTING  

Microsoft Academic Search

A rapid method for diamine oxidase assay is described. The method is ; based on the formation of radioactive toluene-extractable end product(s) from the ; actlon of dlamlne oxidase on cadaverine-C¹⁴. The end products are ; extracted directly into toluene and assayed in a liquid scintillation ; spectrometer. The method is applicable using radioactive putrescine as ; substrate, but does

T. Okuyama; Y. Kobayashi

1961-01-01

449

High energy resolution scintillators for nuclear nonproliferation applications  

NASA Astrophysics Data System (ADS)

The detection of ionizing radiation is important in numerous applications related to national security ranging from the detection and identification of fissile materials to the imaging of cargo containers. A key performance criterion is the ability to reliably identify the specific gamma-ray signatures of radioactive elements, and energy resolution approaching 2% at 662 keV is required for this task. In this work, we present discovery and development of new high energy resolution scintillators for gamma-ray detection. The new ternary halide scintillators belong to the following compositional families: AM2X5:Eu, AMX3, and A2MX4:Eu (A = Cs, K; M = Ca, Sr, Ba; X = Br, I) as well as mixed elpasolites Cs2NaREBr3I3:Ce (RE = La, Y). Using thermal analysis, we confirmed their congruent melting and determined crystallization and melting points. Using the Bridgman technique, we grew 6, 12 and 22 mm diameter single crystals and optimized the Eu concentration to obtain the best scintillation performance. Pulse-height spectra under gamma-ray excitation were recorded in order to measure scintillation light output, energy resolution and light output nonproportionality. The KSr2I5:Eu 4% showed the best combination of excellent crystal quality obtained at fast pulling rates and high light output of ~95,000 photons/MeV with energy resolution of 2.4% at 662 keV.

Zhuravleva, M.; Melcher, C. L.; Stand, L.; Lindsey, A.; Wei, H.; Hobbs, C.; Koschan, M.

2014-09-01

450

Peak asymmetry understanding in ? liquid scintillation with ?\\/? rejection  

Microsoft Academic Search

The alpha liquid scintillation with ?\\/? discrimination is an analytical method of interest for the determination of ? emitters at the trace level. Several authors already suggested its utilization for the detection of radioactivity in environmental samples due to its high sensitivity and a fast sample preparation. Nevertheless, whatever the apparatus used, it suffers a dramatic lack of resolution in

Jean Auplais; Nicolas Dacheux

2000-01-01

451

Restoration of turbulence profile from lunar scintillation A. Tokovinin  

E-print Network

Restoration of turbulence profile from lunar scintillation A. Tokovinin Version 2.1 January 23, 2007 [restoration.tex] 1 Introduction A robust method to evaluate quantitatively ground solar SHABAR ­ in [4]. Profile restoration is also discussed by Kaiser [2]. 2 Weighting functions 36 9

Tokovinin, Andrei A.

452

Optical artefact characterization and correction in volumetric scintillation dosimetry.  

PubMed

The goals of this study were (1) to characterize the optical artefacts affecting measurement accuracy in a volumetric liquid scintillator detector, and (2) to develop methods to correct for these artefacts. The optical artefacts addressed were photon scattering, refraction, camera perspective, vignetting, lens distortion, the lens point spread function, stray radiation, and noise in the camera. These artefacts were evaluated by theoretical and experimental means, and specific correction strategies were developed for each artefact. The effectiveness of the correction methods was evaluated by comparing raw and corrected images of the scintillation light from proton pencil beams against validated Monte Carlo calculations. Blurring due to the lens and refraction at the scintillator tank-air interface were found to have the largest effect on the measured light distribution, and lens aberrations and vignetting were important primarily at the image edges. Photon scatter in the scintillator was not found to be a significant source of artefacts. The correction methods effectively mitigated the artefacts, increasing the average gamma analysis pass rate from 66% to 98% for gamma criteria of 2% dose difference and 2 mm distance to agreement. We conclude that optical artefacts cause clinically meaningful errors in the measured light distribution, and we have demonstrated effective strategies for correcting these optical artefacts. PMID:24321820

Robertson, Daniel; Hui, Cheukkai; Archambault, Louis; Mohan, Radhe; Beddar, Sam

2014-01-01

453

Scintillation, Afterglow and Thermoluminescence of L A Kappers1  

E-print Network

Scintillation, Afterglow and Thermoluminescence of CsI:Tl,Sm L A Kappers1 , R H Bartram1 , D and thermoluminescence on single-crystal samples of CsI:Tl and CsI:Tl,Sm, recorded sequentially at adjusted gain settings, and combined radioluminescence, afterglow and thermoluminescence experiments on single-crystal samples of Cs

Hamilton, Douglas S.

454

Scintillation properties of CsI:In single crystals  

NASA Astrophysics Data System (ADS)

Scintillation properties of CsI:In single crystals have been investigated. Scintillation yield of CsI:In measured with the 24 ?s integration time is around 27,000 ph/MeV, reaching the saturation at 0.005 mol% of the activator. However, luminescence yield of CsI:In is close to CsI:Tl scintillation crystals, which is around 60,000 ph/MeV. This difference is explained by the presence of an ultra-long afterglow in CsI:In scintillation pulse. Thermoluminescence studies revealed a stable trap around 240 K that is supposed to be related to millisecond decay components. The best measured energy resolution of (8.5±0.3)% was achieved at 24 ?s peaking time for a CsI sample doped with 0.01 mol% of In. Temperature stability of CsI:In radioluminescence intensity was found to be remarkably high. Its X-ray luminescence yield remains stable up to 600 K, whereafter thermal quenching occurs. The latter property gives CsI:In a potential to be used in well logging applications.

Gridin, S.; Belsky, A.; Moszynski, M.; Syntfeld-Kazuch, A.; Shiran, N.; Gektin, A.

2014-10-01

455

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

SciTech Connect

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 efficiency while exploiting the power of coincidence to suppress single-PMT "dark current" background; * Utilizing anti-Compton vetoing and supplementary spectral information from a co-located secondary, or "Back" detector, to both (1) minimize Compton background in the low-energy portion of the "Front" scintillator's pulse-height spectrum, and (2) sharpen the statistical accuracy of the front detector's low-energy response prediction as impelmented in suitable energy-windowing algorithms; and * Investigating alternative materials to enhance the intrinsic gamma-ray detection efficiency of plastic-based sensors.

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

2008-02-05

456

Lithium-free scintillation glasses for fast-neutron detection  

NASA Astrophysics Data System (ADS)

In this article, we present observed characteristics of new lithium-free scintillation glasses which have been developed to make time-resolved measurements of the 14-MeV neutron flux from deuterium plasmas. These measurements will yield information on the burnup of tritons in today's deuterium plasmas and are needed to better predict the confinement and slowdown of alpha particles in future D-T burning plasmas. The new glasses were formulated to have good detection efficiency for 14-MeV neutrons, and yet be insensitive to 2.5-MeV and lower-energy neutrons. The glass response to alpha, gamma, and neutron radiation is shown. The intrinsic neutron detection efficiency of the scintillation glass is seen to increase significantly as a function of neutron energy, providing the necessary discrimination against low-energy neutrons. We discuss the reactions which determine the glass neutron response and suggest that this response is dominated at higher neutron energies by gamma rays created by neutrons inelastically scattering from oxygen present in the glass. For high-energy neutron detection in the presence of excessive background gamma radiation, we discuss a new coincidence configuration of lithium-free scintillation glass with NE213 liquid scintillator.

Smith, J. R.; Fisher, R. K.; Leffler, J. S.

1987-10-01

457

A study of liquid scintillator and fiber materials for use in a fiber calorimeter  

SciTech Connect

This reports an investigation into the performance of selected scintillation oils and fiber materials to test their applicability in high energy, liquid scintillator calorimetry. Two scintillating oils, Bicron BC-517 and an oil mixed for the MACRO experiment, and two fiber materials, Teflon and GlassClad PS-252, were tested for the following properties: light yield, attenuation length and internal reflection angle. The results of these tests indicated that the scintillation oils and the fiber materials had an overall good performance with lower energies and would meet the requirements of liquid scintillator detection at SSC energies. 6 refs.

Altice, P.P. Jr.

1990-04-01

458

Guide for Developing an Adaptive Physical Education Curriculum. K-6.  

ERIC Educational Resources Information Center

Methods and techniques for implementing an adapted physical education program are provided in this guide for elementary physical education teachers. The recommended screening test, "Revised Motor Activity Scale," consists of observable items which are not scored and performance items in three categories which are scored: (1) body awareness and…

Hess, Jack, Comp.; And Others

459

ChemTracker 4.0 Inventory Management User Guide  

E-print Network

ChemTracker 4.0 Inventory Management User Guide Part 2: Add Inventory, Add Templates 10 & Household Items · Barcodes · Add Inventory Templates #12;Add Inventory Required Fields © 2013 Stanford University 2 Press Add at the top of the screen to start. 10/11/2013 You will only be able to add inventory

460

Growth and characterization of polycrystalline lanthanide halide scintillators  

NASA Astrophysics Data System (ADS)

We are exploring a novel time- and cost-efficient approach to produce robust, large-volume polycrystalline lanthanide halide scintillators using a hot wall evaporation (HWE) technique. To date, we have fabricated LaBr 3:Ce and LaCl 3:Ce films (slabs) measuring up to 7 cm in diameter and 7+ mm in thickness (20-25 cm 3 in volume) on quartz substrates. These polycrystalline scintillators exhibit very bright emissions approaching those exhibited by their melt-grown crystal counterparts. Scanning electron micrographs (SEMs) and X-ray diffraction analysis confirm polycrystalline growth with columnar structures, both of which help in light piping, thereby contributing to the observed high light yields. The new scintillators also exhibit good energy resolution for ?-rays over the tested range of 60 keV ( 241Am) to 662 keV ( 137Cs), although they have not yet reached that of the corresponding crystals. The measured response linearity over the same energy range is comparable for both our HWE synthesized films and melt-grown commercially-available reference crystals. Similar consistency in response is also observed in terms of their decay time and afterglow behaviors. The data collected so far demonstrate that our HWE technique permits the rapid creation of scintillators with desired structural and compositional characteristics, without the introduction of appreciable defects, and yields material performance equivalent to or approaching that of crystals. Consequently, the deposition parameters may be manipulated to tailor the physical and scintillation performance of the resulting structures, while achieving a cost per unit volume that is substantially lower than that of crystals. In turn, this promises to allow the use of these novel scintillation materials in such applications as SPECT, PET, room-temperature radioisotope identification and homeland security, where large volumes of materials in a wide variety of shapes and sizes are needed. This paper describes our growth and testing of polycrystalline LaBr 3:Ce scintillators and provides comparative characterizations of their performance with crystals.

Nagarkar, V. V.; Miller, S. R.; Gelfandbein, V.; Shirwadkar, U.; Gaysinskiy, V.

2011-10-01