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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

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

3

Quick Use Guide Workcentre 5655 Touch Screen  

E-print Network

Panel (Touch Screen/User Interface) Document Feeder Door Tray 2 Bypass Tray Tray 4 Offset Catch TrayQuick Use Guide Workcentre 5655 Touch Screen Displays and selects all of the available programming right). 2. Access the Basic Copy Screen ­ If necessary select the [Features] button on the control panel

Petriu, Emil M.

4

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

NASA Astrophysics Data System (ADS)

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

Gopal, Arun

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

Screening and Evaluation Tool (SET) Users Guide  

SciTech Connect

This document is the users guide to using the Screening and Evaluation Tool (SET). SET is a tool for comparing multiple fuel cycle options against a common set of criteria and metrics. It does this using standard multi-attribute utility decision analysis methods.

Layne Pincock

2014-10-01

7

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

8

Characterization of scintillator screens for suprathermal ion detection in fusion devices  

NASA Astrophysics Data System (ADS)

The luminescence of scintillator screens of Y3Al5O12:Ce3+ (P46), Gd2O2S:Tb3+ (P43), Y2O3:Eu3+ (P56) and SrGa2S4:Eu2+ (TG-Green) has been characterized when irradiated with deuterium ions and ?-particles with energies up to 3 MeV. The relative efficiency of the scintillator layers deposited on stainless steel plates has been studied as a function of beam energy and current as well as ion species. The emitted light first increases linearly with beam energy and then saturates. A logarithmic decay of the efficiency with beam current has been observed for all scintillators. Furthermore, the scintillator degradation by high ion dose has been investigated. Among the screens under study, the TG-Green and P46 scintillators are the best suited materials, in terms of relative efficiency and degradation with ion dose, for fast-ion loss detection in fusion devices.

García-Muñoz, M.; Jimenez-Rey, D.; García-Lopez, J.; Zurro, B.; Baciero, A.; Fahrbach, H.-U.; McCarthy, K. J.

2011-04-01

9

Fluorescence-guided OCT for Colon Cancer Screening  

E-print Network

Fluorescence-guided OCT for Colon Cancer Screening A Critical Review of "Fluorescence-guided Optical Coherence Tomography Imaging for Colon Cancer Screening: A Preliminary Mouse Study" - Iftimia et (aka Team Beard) #12;Background · What is the problem? · How do we currently find colon cancer

George, Steven C.

10

Distributed Radiation Sensor with Flexible Light Guide filled with Liquid Organic Scintillator  

Microsoft Academic Search

Position sensitive detectors with optical fibers (e.g. scintillating fiber, normal optical plastic fiber, liquid light guide) have been developed for a long range distributed radiation sensing to monitor nuclear facilities, because they have great advantages like long lengths, flexibility in configuration, immunity to electromagnetic fields. However, there are some problems to apply these detectors in the high-level radiation environments. In

Jun Kawarabayashi; Yusuke Takebe; Norihiro Naoi; Keisuke Asai; Kenichi Watanabe; Tetsuo Iguchi

2006-01-01

11

Multiple phase screen modeling of ionospheric scintillation along radio occultation raypaths  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

12

Intensity Scintillations in Planetary Rings Occultation: Theory  

Microsoft Academic Search

We use the classical diffraction screen approach to develop a theoretical foundation for investigation of the intensity scintillations observed during stellar occultation of the Voyager spacecraft by Saturn's rings (Showalter and Nicholson, Icarus 87, 285-306, 1990). The formulation is guided by procedures developed for analysis of scintillations of stars observed through the turbulent Earth atmosphere and of natural radio sources

Essam A. Marouf

1998-01-01

13

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

EPA Science Inventory

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

14

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

15

On the response of Y 3Al 5O 12: Ce (YAG: Ce) powder scintillating screens to medical imaging X-rays  

Microsoft Academic Search

The aim of this study was to examine Y3Al5O12:Ce (also known as YAG:Ce) powder scintillator under X-ray imaging conditions. This material shows a very fast scintillation decay time and it has never been used in X-ray medical imaging. In the present study various scintillator layers (screens) with coating thickness ranging from 13 to 166mg\\/cm2 were prepared in our laboratory by

I. Kandarakis; D. Cavouras; I. Sianoudis; D. Nikolopoulos; A. Episkopakis; D. Linardatos; D. Margetis; E. Nirgianaki; M. Roussou; P. Melissaropoulos; N. Kalivas; I. Kalatzis; K. Kourkoutas; N. Dimitropoulos; A. Louizi; C. Nomicos; G. Panayiotakis

2005-01-01

16

Preimplantation Genetic Screening: A Practical Guide  

PubMed Central

The past several decades have seen tremendous advances in the field of medical genetics. The application of genetic technologies to the field of reproductive medicine has ushered in a new era of medicine that is likely to greatly expand in the coming years. Concurrent with an in vitro fertilization (IVF) cycle, it is now possible to obtain a cellular biopsy from a developing embryo and genetically evaluate this sample with increasing sophistication and detail. Preimplantation genetic screening (PGS) is the practice of determining the presence of aneuploidy (either too many or too few chromosomes) in a developing embryo. However, how and in whom PGS should be offered is a topic of much debate. PMID:24453517

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

2013-01-01

17

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

18

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

NASA Astrophysics Data System (ADS)

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 µm 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.

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

2010-06-01

19

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

Microsoft Academic Search

Plastic scintillators have many advantages for dosimetry in external beam radiotherapy. The current method of transmitting the scintillation light to a remote detector is through a solid core optical fibre. When exposed in a high energy therapeutic radiotherapy beam this fibre is subject to an unwanted background signal from Cerenkov light which can exceed the scintillation signal at characteristic angles.

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

2008-01-01

20

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

21

Scintillation Counters  

NASA Astrophysics Data System (ADS)

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

Bell, Zane W.

22

Positioning accuracy and precision of a three-degrees-of-freedom manipulator guided by tilting-collimator scintillation camera  

Microsoft Academic Search

In our previous studies we have considered a possible use of a manipulator for biomedical applications guided by the so-called tilting-collimator (TC) scintillation gamma-ray camera. The imaged gamma-ray emitting object is localized exploiting our patented method to determine the camera-to-object distance using a TC camera (patent No RM 2006 A 000216, UIBM Roma). Thus the three coordinates of the object

Nikolay M. Uzunov; Michele Bello; Pasquale Boccaccio; Giuliano Moschini; Dante Bollini; Giuseppe Baldazzi; Roberto Pani

2008-01-01

23

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

SciTech Connect

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

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

2006-06-15

24

On the performance of scintillation screens and radiographic films at the acquisition of images using thermal neutrons and X-rays  

Microsoft Academic Search

The performance of image acquiring systems operating by transmission of thermal neutrons and X-rays have been evaluated and compared. In both systems radiographic films have been used to catch the transmitted images, while that one using a reactor as thermal neutron source utilized also a scintillation screen for the same purpose. Images of several objects have been taken with those

R. T. Lopes; M. I. Silvani; R. Furieri; G. L. de Almeida; M. J. Goncalves

2005-01-01

25

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

Microsoft Academic Search

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

Spicer

1976-01-01

26

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

SciTech Connect

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

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

2009-11-15

27

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

28

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

29

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

ERIC Educational Resources Information Center

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

Deal, Gerald A.; Montgomery, James A.

30

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

31

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

32

Biomarker-guided screening of Juzen-taiho-to, an Oriental herbal formulation for immmunostimulation  

PubMed Central

Juzen-taiho-to (JTT) 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 (M?). Although JTT 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 M? stimulatory activity. To this end, gene expression was analyzed by a DNA array for M? treated with JTT and DMSO (vehicle control), which identified intercellular adhesion molecule 1 (ICAM-1) as a biomarker of M?-stimulation by JTT. A qRT-PCR assay of ICAM-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 ICAM-1 expression in primary dendritic cells (DC) as well as in primary CD14+ (M?) cells. Identification of this glycolipid mixture opens an opportunity for further studies to understand how plant-derived glycolipids stimulate M? and DC in a safe and effective manner as demonstrated by JTT. PMID:24549928

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

2014-01-01

33

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

34

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

35

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

36

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

EPA Science Inventory

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

37

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

38

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

ERIC Educational Resources Information Center

Utilizing a community-based participatory research (CBPR) approach is a potentially effective strategy for exploring the development, implementation, and evaluation of HIV interventions in African American churches. This CBPR-guided study describes a church-based HIV awareness and screening intervention (Taking It to the Pews [TIPS]) that fully…

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

2010-01-01

39

Scintillator material  

DOEpatents

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

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

1992-07-28

40

Scintillator material  

DOEpatents

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

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

1994-06-07

41

Scintillator material  

DOEpatents

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

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

1994-01-01

42

Scintillator material  

DOEpatents

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

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

1992-01-01

43

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.

44

Scintillation Mathematics  

E-print Network

, in particular, when low margin systems are employed. #15; Various models of scintillation have been proposed, with an elevation angle of 40 � . #15; The sampling rate was 18.66 Hz, sufficient for a detailed study of tropospheric scintillation. #15; The data has been divided into rain and non­rain periods by using a radiometer

Baxter, Paul D.

45

An equatorial scintillation model  

NASA Astrophysics Data System (ADS)

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

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

1985-09-01

46

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.

47

Plastic scintillation dosimetry: Optimal selection of scintillating fibers and scintillators  

Microsoft Academic Search

Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for

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

2005-01-01

48

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?

Bob Riddle

2003-02-01

49

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

PubMed Central

Utilizing a community-based participatory research (CBPR) approach is a potentially effective strategy for exploring the development, implementation, and evaluation of HIV interventions in African American churches. This CBPR-guided study describes a church-based HIV awareness and screening intervention (Taking It to the Pews [TIPS]) that fully involved African American church leaders in all phases of the research project. Findings from the implementation and evaluation phases indicated that church leaders delivered TIPS Tool Kit activities on an ongoing basis (about twice a month) over a 9-month period. TIPS church members were highly exposed to TIPS activities (e.g., 91% reported receiving HIV educational brochures, 84% heard a sermon about HIV). Most (87%) believed that the church should talk about HIV, and 77% believed that the church should offer HIV screening. These findings suggest that implementing an HIV intervention in Black church settings is achievable, particularly when a CBPR approach is used. PMID:20528130

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

2014-01-01

50

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

PubMed

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

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

2014-03-01

51

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

PubMed

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

Ratnayake, Sunil; Lewandowski, Paul

2010-01-01

52

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

Cancer.gov

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

53

Scintillation camera  

SciTech Connect

Photomultiplier tubes for converting photons converted from radiant rays by a scintillator into electric signals are severally connected to preamplifiers. The outputs of the preamplifiers are connected to weighting resistors through nonlinear amplifying circuits. The nonlinear amplifying circuit nonlinearly amplifies the output signals of each two adjacent preamplifiers in accordance with the correlation between the output signals of the preamplifiers, thereby producing two output signals.

Tomita, Y.

1981-06-16

54

Screening.  

PubMed

Screening is the only practical approach for improving the management of hepatocellular carcinoma (HCC) patients, as early detection increases the application of curative treatments. A conference of experts from Japan, USA, and Europe (Barcelona 2005) advised surveillance every six months for patients with chronic liver disease at increased risk of HCC with abdominal US. Whether this approach benefits HCC patients in terms of survival is still uncertain, since available data are retrospective and biased by lead-time factors in the calculation of patient survival. Only one randomized controlled study in China showed the benefit of surveillance for HCC; however, in a population-based setting. Today, clinic-based, randomized studies are unfeasible for ethical reasons. In a cohort of 447 Italian patients with compensated cirrhosis, we compared the survival of HCC patients identified along three consecutive quinquennia of surveillance. HCC developed in 112 patients (3.4% per year) and was the prime cause of death. Forty-six patients (41%) had a single tumor with mean sizes of 3.7, 3.0, and 2.2 cm in the three quinquennia (first vs third, P = 0.0147; second vs third, P = 0.02) and 38(44%) underwent radical therapies. Mortality rates in HCC patients fell from 45% in the first quinquennium to 10% in the third (P = 0.0009), in parallel with a reduction in mortality of treated patients (34, 28, and 5%) (first vs third, P = 0.0024). Cirrhotic patients developing HCC during the last five years of surveillance survived longer than previously, as a consequence of improved management of the tumor and complications of cirrhosis. It remains controversial whether HCC screening is cost-effective, i.e. whether the cost of detection, confirmatory studies, and treatment are outbalanced by the number of life-years gained. In a retrospective study of Italian patients with cirrhosis, there was an incremental cost-efficacy ratio of surveillance vs no surveillance to be $USD 112 993 per liver-year saved. The cost of surveillance was increased by surgery applied to 15 patients with HCC detected during surveillance. PMID:17877477

Colombo, Massimo

2007-09-01

55

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

PubMed

Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for four commercial models of scintillating fibers (BCF-12, BCF-60, SCSF-78, SCSF-3HF) and two models of plastic scintillators (BC-400, BC-408). The emission spectra of all six scintillators were obtained by using an optical spectrum analyzer and they were compared with theoretical behavior. For scintillation in the blue region, the signal intensity of a singly clad scintillating fiber (BCF-12) was 120% of that of the plastic scintillator (BC-400). For the multiclad fiber (SCSF-78), the signal reached 144% of that of the plastic scintillator. The intensity of the green scintillating fibers was lower than that of the plastic scintillator: 47% for the singly clad fiber (BCF-60) and 77% for the multiclad fiber (SCSF-3HF). The collected light was studied as a function of the scintillator length and radius for a cylindrical probe. We found that symmetric detectors with nearly the same spatial resolution in each direction (2 mm in diameter by 3 mm in length) could be made with a signal equivalent to those of the more commonly used asymmetric scintillators. With augmentation of the signal-to-noise ratio in consideration, this paper presents a series of comparisons that should provide insight into selection of a scintillator type and volume for development of a medical dosimeter. PMID:16121582

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

2005-07-01

56

Plastic scintillation dosimetry: Optimal selection of scintillating fibers and scintillators  

SciTech Connect

Scintillation dosimetry is a promising avenue for evaluating dose patterns delivered by intensity-modulated radiation therapy plans or for the small fields involved in stereotactic radiosurgery. However, the increase in signal has been the goal for many authors. In this paper, a comparison is made between plastic scintillating fibers and plastic scintillator. The collection of scintillation light was measured experimentally for four commercial models of scintillating fibers (BCF-12, BCF-60, SCSF-78, SCSF-3HF) and two models of plastic scintillators (BC-400, BC-408). The emission spectra of all six scintillators were obtained by using an optical spectrum analyzer and they were compared with theoretical behavior. For scintillation in the blue region, the signal intensity of a singly clad scintillating fiber (BCF-12) was 120% of that of the plastic scintillator (BC-400). For the multiclad fiber (SCSF-78), the signal reached 144% of that of the plastic scintillator. The intensity of the green scintillating fibers was lower than that of the plastic scintillator: 47% for the singly clad fiber (BCF-60) and 77% for the multiclad fiber (SCSF-3HF). The collected light was studied as a function of the scintillator length and radius for a cylindrical probe. We found that symmetric detectors with nearly the same spatial resolution in each direction (2 mm in diameter by 3 mm in length) could be made with a signal equivalent to those of the more commonly used asymmetric scintillators. With augmentation of the signal-to-noise ratio in consideration, this paper presents a series of comparisons that should provide insight into selection of a scintillator type and volume for development of a medical dosimeter.

Archambault, Louis; Arsenault, Jean; Gingras, Luc; Sam Beddar, A.; Roy, Rene; Beaulieu, Luc [Departement de Radio-Oncologie et Centre de Recherche en Cancerologie, Hotel-Dieu de Quebec, 11 cote du palais, Quebec, Quebec G1R 2J6 (Canada) and Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec (Canada); Department of Radiation Physics, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030 (United States); Department de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec (Canada); Departement de Radio-Oncologie et Centre de Recherche en Cancerologie, Hotel-Dieu de Quebec, 11 cote du palais, Quebec, Quebec G1R 2J6 (Canada) and Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec (Canada)

2005-07-15

57

Daily targeting of liver tumors: Screening patients with a mock treatment and using a combination of internal and external fiducials for image-guided respiratory-gated radiotherapy  

SciTech Connect

The feasibility and accuracy of using a mock treatment to screen suitable patients for respiratory-gated image-guided radiotherapy was investigated. Radio-opaque fiducials implanted adjacent to the liver tumor were used for online positioning to minimize the systematic error in patient positioning. The consistency in the degree of correlation between the external and internal fiducials was analyzed during a mock treatment. This technique could screen patients for gated therapy, reduce setup inaccuracy, and possibly individualize treatment margins.

Krishnan, Sunil; Briere, Tina Marie; Dong Lei; Murthy, Ravi; Ng, Chaan; Balter, Peter; Mohan, Radhe; Gillin, Michael T.; Beddar, A. Sam [Department of Radiation Oncology, MD Anderson Cancer Center, Houston, Texas 77030 (United States); Department of Radiation Physics, MD Anderson Cancer Center, Houston, Texas 77030 (United States); Department of Diagnostic Radiology, MD Anderson Cancer Center, Houston, Texas 77030 (United States); Department of Radiation Physics, MD Anderson Cancer Center, Houston, Texas 77030 (United States)

2007-12-15

58

NMR screening in fragment-based drug design: a practical guide.  

PubMed

Fragment-based drug design (FBDD) comprises both fragment-based screening (FBS) to find hits and elaboration of these hits to lead compounds. Typical fragment hits have lower molecular weight (<300-350 Da) and lower initial potency but higher ligand efficiency when compared to those from high-throughput screening. NMR spectroscopy has been widely used for FBDD since it identifies and localizes the binding site of weakly interacting hits on the target protein. Here we describe ligand-based NMR methods for hit identification from fragment libraries and for functional cross-validation of primary hits. PMID:25618347

Kim, Hai-Young; Wyss, Daniel F

2015-01-01

59

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

SciTech Connect

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

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

1993-11-01

60

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

EPA Science Inventory

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

61

Large volume flow-through scintillating detector  

DOEpatents

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

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

1995-01-01

62

Metabolomics Guides Rational Development of a Simplified Cell Culture Medium for Drug Screening against Trypanosoma brucei  

PubMed Central

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.

2013-01-01

63

Polyvinyltoluene scintillators for relative ion dosimetry: An investigation with Helium, Carbon and Neon beams  

Microsoft Academic Search

We present a dosimeter prototype, devoted to ion beam dosimetry, tested with Helium, Carbon and Neon ions having an equivalent range in water of 150mm. A polyvinyltoluene based plastic scintillator is used to convert the deposited energy into scintillation, a measurement probe and a long optical fibre guide the light to a photon counting unit. Using 10–40?m thick scintillators we

David Broggio; Rémi Barillon; Jean-Marc Jung; Nakahiro Yasuda; Tomoya Yamauchi; Hisashi Kitamura; Pierre Bischoff

2007-01-01

64

Further determinations of strong scintillation effects on GNSS signals using the Hybrid Scintillation Propagation Model  

NASA Astrophysics Data System (ADS)

The effect of strong scintillation conditions on GNSS transionospheric paths of propagation is further investigated employing the most recent update of the Hybrid Scintillation Propagation Model (HSPM). The variation of various parameters including spectral indices and other statistical moments of the field is studied as a function of the severity of the signal fluctuations. The correlation time of the complex amplitude of the field is found to rapidly decrease as the scintillation severity increases, but by contrast, the intensity correlation time stays almost constant over a wide range of S4 showing only slight decrease in the model's range of validity. The dependence of the spectral indices of both phase and amplitude on S4 is also determined, and the spectral index of the phase fluctuations tends to 2 for the most severe scintillation, as expected from both experiment and theory. The effect of "canonical fading" is also studied, when, in the conditions of strong scintillation, fast phase changes occur along with deep amplitude fades. The probability of the effect of the "canonical fading" is studied for the conditions of strong scintillation, and the mean time between cycle slips shows a significant decrease as S4 increases. A comparison is also presented between calculated results of S4, spectral indices, and the correlation radii of the complex field and field intensity, utilizing both the HPSM and equivalent phase screen model for both weak and strong scintillation conditions. These show the differences that can occur which can also depend on the equivalent phase screen height.

Zernov, Nikolay N.; Gherm, Vadim E.; Strangeways, Hal J.

2012-04-01

65

Expression of translationally controlled tumor protein (TCTP) gene of Dirofilaria immitis guided by transcriptomic screening.  

PubMed

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; Yang, Guangyou

2014-02-01

66

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

67

Scintillator efficiency study with MeV x-rays  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

68

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

PubMed

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

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

2013-05-01

69

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

PubMed Central

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

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

2013-01-01

70

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

71

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

72

Lead carbonate scintillator materials  

DOEpatents

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

Derenzo, Stephen E. (Pinole, CA); Moses, William W. (Berkeley, CA)

1991-01-01

73

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

74

In search of allosteric modulators of a7-nAChR by solvent density guided virtual screening.  

PubMed

Nicotinic acetylcholine receptors (nAChR) are pentameric ligand gated ion channels whose activity can be modulated by endogenous neurotransmitters as well as by synthetic ligands that bind the same or distinct sites from the natural ligand. The subtype of ?7 nAChR has been considered as a potenial therapeutic target for Alzheimer's disease, schizophrenia and other neurological and psychiatric disorders. Here we have developed a homology model of ?7 nAChR based on two high resolution crystal structures with Brookhaven Protein Data Bank (PDB) codes 2QC1 and 2WN9 for threading on one monomer and then for building a pentamer, respectively. A number of small molecule binding sites are identified using Pocket Finder (J. An, M. Tortov, and R. Abagyan, Molecular & Cellular Proteomics, 4.6, 752-761 (2005)) of Internal Coordinate Mechanics (ICM). Remarkably, these computer-identified sites match perfectly with ordered solvent densities found in the high-resolution crystal structure of ?1 nAChR, suggesting that the surface cavities in the ?7 nAChR model are likely binding sites of small molecules. A high throughput virtual screening by flexible ligand docking of 5008 small molecule compounds was performed at three potential allosteric modulator (AM) binding sites of ?7 nAChR using Molsoft ICM software (R. Abagyan, M. Tortov and D. Kuznetsov, J Comput Chem 15, 488-506, (1994)). Some experimentally verified allosteric modulators of ?7 like CCMI comp-6, LY 7082101, 5-HI, TQS, PNU-120596, genistein, and NS-1738 ranked among top 100 compounds, while the rest of the compounds in the list could guide further search for new allosteric modulators. PMID:21294583

Dey, Raja; Chen, Lin

2011-04-01

75

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

76

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

77

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

78

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

79

The Use of Energy Information in Plastic Scintillator Material  

SciTech Connect

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

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

2008-06-15

80

GPS and ionospheric scintillations  

NASA Astrophysics Data System (ADS)

Ionospheric scintillations are one of the earliest known effects of space weather. Caused by ionization density irregularities, scintillating signals change phase unexpectedly and vary rapidly in amplitude. GPS signals are vulnerable to ionospheric irregularities and scintillate with amplitude variations exceeding 20 dB. GPS is a weak signal system and scintillations can interrupt or degrade GPS receiver operation. For individual signals, interruption is caused by fading of the in-phase and quadrature signals, making the determination of phase by a tracking loop impossible. Degradation occurs when phase scintillations introduce ranging errors or when loss of tracking and failure to acquire signals increases the dilution of precision. GPS scintillations occur most often near the magnetic equator during solar maximum, but they can occur anywhere on Earth during any phase of the solar cycle. In this article we review the subject of GPS and ionospheric scintillations for scientists interested in space weather and engineers interested in the impact of scintillations on GPS receiver design and use.

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

2007-09-01

81

An equatorial scintillation model  

Microsoft Academic Search

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

E. J. Fremouw; R. E. Robins

1985-01-01

82

Toxic chemical release inventory risk screening guide (Version 1. 0). Volume 1. The process. Volume 2. Appendices. Final report  

SciTech Connect

The guide describes some of the challenges raised by the Toxic Release Inventory (TRI) data and to suggest ways of approaching them. The guide suggests steps that can be taken to answer two key issues of concern: setting risk-based priorities for followup investigation of the TRI facilities and chemicals within geographic area of interest, and identifying data needs and approaches for collecting information necessary to respond to health and ecological questions from the public. The guide is directed at those individuals who are involved in interpreting and explaining environmental pollution, exposures, and health risks to the general public, especially at the local or sub-State level. Many users of the guide will already be well versed in evaluating risk and/or in helping members of the public understand and deal with toxic chemicals, but Title 111 - particularly, the Section 313 release data - presents new challenges for everyone.

Klauder, D.; Saunders, L.

1989-07-01

83

Boron-Loaded Liquid Scintillation Neutron Detectors  

Microsoft Academic Search

The general problems involved in constructing boron-loaded liquid scintillation neutron detectors are considered. The characteristics of particular counters which have been successfully used in neutron transmission measurements by the time-of-flight method are then described. The design of these counters was guided by the results of a Monte Carlo study of neutron capture in a boron-poisoned medium. This calculation gives the

Lowell M. Bollinger; George E. Thomas

1957-01-01

84

Characterization of one-dimensional fiber-optic scintillating detector for electron beam therapy dosimetry  

Microsoft Academic Search

In this study, a one-dimensional fiber-optic scintillating detector is developed for electron beam therapy dosimetry. Each fiber-optic detector has an organic scintillator as a sensitive volume and it is embedded and arrayed in the plastic phantom to measure one-dimensional high energy electron beam profile of clinical linear accelerator (CLINAC). The scintillating lights generated from each detector probe are guided by

Bongsoo Lee; Dong Hyun Cho; Kyoung Won Jang; Wook Jae Yoo; Sang Hoon Shin; Gye-Rae Tack; Sin Kim; Hyosung Cho

2007-01-01

85

Characterization of One-Dimensional Fiber-Optic Scintillating Detectors for Electron-Beam Therapy Dosimetry  

Microsoft Academic Search

In this study, a one-dimensional fiber-optic scintillating detector was developed for electron-beam therapy dosimetry. Each fiber-optic detector contains an organic scintillator as a sensitive volume and it is embedded and arrayed in a plastic phantom to measure one-dimensional high-energy electron-beam profiles of clinical linear accelerators. Plastic optical fibers guide the scintillating light which each detector probe generates to a photodiode

Bongsoo Lee; Kyoung Won Jang; Dong Hyun Cho; Wook Jae Yoo; Sang Hun Shin; Gye-Rae Tack; Soon-Cheol Chung; Sin Kim; Hyosung Cho; Byung Gi Park; Joo Hyun Moon; Siyong Kim

2008-01-01

86

An Educational Resource for Teachers The giant screen film, GRAND CANYON ADVENTURE: RIVER AT RISK, and thisTeacher's Guide  

E-print Network

ADVENTURE: RIVER AT RISK is the captivating story of the worldwide water crisis and the great drought now plaguing the American Southwest. Audiences will join a team of explorers on an exhilarating Colorado River#12;An Educational Resource for Teachers The giant screen film, GRAND CANYON ADVENTURE: RIVER

Mathis, Wayne N.

87

OPTIMAL WELL LOCATOR (OWL): A SCREENING TOOL FOR EVALUATING LOCATIONS OF MONITORING WELLS: USER'S GUIDE VERSION 1.2  

EPA Science Inventory

The Optimal Well Locator ( OWL) program was designed and developed by USEPA to be a screening tool to evaluate and optimize the placement of wells in long term monitoring networks at small sites. The first objective of the OWL program is to allow the user to visualize the change ...

88

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

89

Simulating intergalactic quasar scintillation  

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

90

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

91

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

92

Study of scintillation in natural and synthetic quartz and methacrylate  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

93

Study of scintillation in natural and synthetic quartz and methacrylate  

E-print Network

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

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

2014-01-01

94

Study of scintillation in natural and synthetic quartz and methacrylate  

E-print Network

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

J. Amare; S. Borjabad; S. Cebrian; C. Cuesta; D. Fortuno; E. Garcia; C. Ginestra; H. Gomez; D. C. Herrera; M. Martinez; M. A. Olivan; Y. Ortigoza; A. Ortiz de Solorzano; C. Pobes; J. Puimedon; M. L. Sarsa; J. A. Villar; P. Villar

2014-03-27

95

Neutron scintillators using wavelength shifting fibers  

SciTech Connect

A proposed design for an optically-based, one-dimension scintillation detector to replace the gas-filled position-sensitive proportional counter currently used for a wide-angle neutron detector (WAND) at the high-Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) is presented. The scintillator, consisting of a mixture of {sup 6}LiF and ZnS(Ag) powders in an epoxy binder, is coupled to an array of wavelength shifting optical fibers which provide position resolution. The wide-angle neutron detector is designed to cover a 120 degree arc with a 75 cm radius of curvature. The final detector design provides for 600 optical fibers coupled to the scintillator screen with an angular resolution of 0.2 degrees. Each individual pixel of the detector will be capable of operating at count rates exceeding 1 MHz. Results are presented from the measurement of neutron conversion efficiencies for several screen compositions, gamma-ray sensitivity, and spatial resolution of a 16 element one-dimensional array prototype.

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

1995-06-01

96

Modeling of ionospheric scintillation at low-latitude  

NASA Astrophysics Data System (ADS)

The presence and movement of plasma density fluctuations in the F-region of the ionosphere are studied by monitoring phase and amplitude of radio waves propagating through the region. In this paper, we have used weak scattering theory and assumed the plasma density fluctuations to behave like phase changing diffraction screen. Appropriate relations for scintillation index S4, and phase variance ?? are derived and computed for different parameters of the plasma density irregularities of the ionosphere. SROSS-C2 satellite in situ measurements of plasma density fluctuations, which provide direct information about the structure and morphology of irregularities that are responsible for scintillation of radio waves, were used first time to develop a scintillation model for low latitude. It is observed that the scintillation index S4 and phase variance ?? depends on the strength of the plasma turbulence. Finally, the results obtained from modeling are compared and discussed with the available recent results.

Patel, K.; Singh, Ashutosh K.; Subrahmanyam, P.; Singh, A. K.

2011-02-01

97

Discrimination of Naturally Occurring Radioactive Material in Plastic Scintillator Material  

SciTech Connect

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

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

2003-08-19

98

Breast Cancer Detection with Short-Interval Follow-up Compared with Return to Annual Screening in Patients with Benign Stereotactic or US-guided Breast Biopsy Results.  

PubMed

Purpose To compare the cancer detection rate and stage after benign stereotactic or ultrasonography (US)-guided core breast biopsy between patients with short-interval follow-up (SIFU) and those who return to annual screening. Materials and Methods The Breast Cancer Surveillance Consortium (BCSC) registry and the BCSC Statistical Coordinating Center received institutional review board approval for active and passive consent processes and a waiver of consent. All procedures were HIPAA compliant. BCSC data for 1994-2010 were used to compare ipsilateral breast cancer detection rates and tumor characteristics for diagnoses within 3 months after SIFU (3-8 months) versus return to annual screening (RTAS) mammography (9-18 months) after receiving a benign pathology result from image-guided breast biopsy. Results In total, 17 631 biopsies with benign findings were identified with SIFU or RTAS imaging. In the SIFU group, 27 ipsilateral breast cancers were diagnosed in 10 715 mammographic examinations (2.5 cancers per 1000 examinations) compared with 16 cancers in 6916 mammographic examinations in the RTAS group (2.3 cancers per 1000 examinations) (P = .88). Sixteen cancers after SIFU (59%; 95% confidence interval [CI]: 39%, 78%) were invasive versus 12 after RTAS (75%; 95% CI: 48%, 93%). The invasive cancer rate was 1.5 per 1000 examinations after SIFU (95% CI: 0.9, 2.4) and 1.7 per 1000 examinations (95% CI: 0.9, 3.0) after RTAS (P = .70). Among invasive cancers, 25% were late stage (stage 2B, 3, or 4) in the SIFU group (95% CI: 7%, 52%) versus 27% in the RTAS group (95% CI: 6%, 61%). Positive lymph nodes were found in seven (44%; 95% CI: 20%, 70%) invasive cancers after SIFU and in three (25%; 95% CI: 5%, 57%) invasive cancers after RTAS. Conclusion Similar rates of cancer detection were found between SIFU and RTAS after benign breast biopsy with no significant differences in stage, tumor size, or nodal status, although the present study was limited by sample size. These findings suggest that patients with benign radiologic-pathologic-concordant percutaneous breast biopsy results could return to annual screening. PMID:25423143

Johnson, Jason M; Johnson, Alisa K; O'Meara, Ellen S; Miglioretti, Diana L; Geller, Berta M; Hotaling, Elise N; Herschorn, Sally D

2015-04-01

99

Surface preparation and coupling in plastic scintillator dosimetry.  

PubMed

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

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

2006-09-01

100

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

101

Liquid Scintillator Purification  

SciTech Connect

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

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

2005-09-08

102

Geomagnetic Control of Satellite Scintillations  

Microsoft Academic Search

Satellite scintillations may be divided into three basic types- (1) low-angle scintil- lations of both tropospheric and ionospheric origin; (2) clouds or patches of ionization con- raining irregularities iiicluding sporadic E; and (3) precipitation scintillation occurring for the most part at heights of 300 to 500 kin. The third type is discin detail; the hypothesis is advanced that this basic

J. Aarons; J. Mullen; Sunanda Basu

1963-01-01

103

Position Reconstruction in Scintillation Detectors  

E-print Network

Chapter 5 Position Reconstruction in Scintillation Detectors Borexino is one of a new generation of position reconstruction for scintillator-based, unsegmented detectors, and the spatial resolutions that may the 201 #12;Chapter 5. Position Reconstruction in Scintillation Detectors 202 detector [55, 63

104

Boron loaded scintillator  

DOEpatents

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

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

2009-10-20

105

New Lutetium Silicate Scintillators  

Microsoft Academic Search

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

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

2000-01-01

106

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

107

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

108

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

109

Bioactivity-guided fast screen and identification of cancer metastasis chemopreventive components from raw extracts of Murraya exotica.  

PubMed

Murraya exotica is a traditional Chinese medicine (TCM) widely grown in southeast China. We herein proposed a fast strategy for separation and identification of active components of cancer metastatic chemopreventives from the root, leaf, twig and stem bark extracts that were obtained by reflux in 80% acidic ethanol and then liquid-liquid extraction. High performance liquid chromatography (HPLC) analysis showed that the extract mixtures from leaf, bark and twig were similar, while the root extract contained a characteristic component (CM1). Bioactivity assays revealed that the root extract contained some active components that significantly inhibited cancer cell viability and migration. Ultra performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (UPLC-DAD-ESI-MS) analysis indicated the existence of coumarins in the root and leaf extracts. Semi-preparative chromatographic separation and physicochemical characterization indicated that CM1 was a novel coumarin derivative that warrants further chemopreventive studies on cancer metastasis. The present phytochemical and phytopharmacological studies exemplify a fast strategy for screening and identifying active component(s) from raw extracts of phytomedicines. PMID:25645338

Jiang, Zhou; Yang, Jina; Pang, Yaqiong; Yang, Xintian; Yu, Suhong; Jia, Lee

2015-03-25

110

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

111

Scintillating fiber optics and their application in radiographic systems  

SciTech Connect

This presents research to evaluate scintillating fiber optics (SFO's) as x-ray radiation imaging detectors. Currently, phosphor screens are used in radiographic x-ray systems. To enhance their detection efficiency requires thicker screens, which inevitably results in degradation of spatial resolution from lateral light dispersion. Scintillating fiber optics combine scintillating material with a dielectric waveguide. This configuration permits an increase in thickness of the scintillating material without significant dispersion of light, therefore, preserving spatial resolution with increased detection efficiency. This characteristic is advantageous for imaging of high-energy x-rays. A model, based on the basic physics of SFO's and the Monte Carlo modeling of radiation, was developed. The model provides a basis for analysis of the performance characteristics of SFO's which are important to their applications as radiation image detectors. An experimental evaluation of the performance of SFO's as radiation imaging detectors is reported. In this study, two types of Tb{sub 2}O{sub 3{minus}} based SFO's were studied using monoenergetic gamma rays, and both low- and high-energy x-ray sources. The study evaluated the overall detector efficiency by combining experimental measurements and analytical Monte Carlo methods. It was found that the detector efficiency was low when compared to phosphor screen. This, however, was due to low light production and not radiation efficiency. Therefore, through the use of light amplification, low detector efficiency was compensated for without affecting spatial resolution.

Shao, H.; Miller, D.W.; Pearsall, C.R. (Ohio State Univ., Columbus, OH (United States). Dept. of Nuclear Engineering)

1991-04-01

112

A computer model of high-latitude scintillation  

NASA Astrophysics Data System (ADS)

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

Fremouw, E. J.

1982-01-01

113

Computer model of high-latitude scintillation. [WBMOD program  

SciTech Connect

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

Fremouw, E.J.

1982-01-01

114

Scintillation Proximity Assay of Arginine Methylation  

PubMed Central

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

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

2011-01-01

115

The Origin of Radio Scintillation In the Local Interstellar Medium  

E-print Network

We study three quasar radio sources (B1257-326, B1519-273, and J1819+385) that show large amplitude intraday and annual scintillation variability produced by the Earth's motion relative to turbulent-scattering screens located within a few parsecs of the Sun. We find that the lines of sight to these sources pass through the edges of partially ionized warm interstellar clouds where two or more clouds may interact. From the gas flow vectors of these clouds, we find that the relative radial and transverse velocities of these clouds are large and could generate the turbulence that is responsible for the observed scintillation. For all three sight lines the flow velocities of nearby warm local interstellar clouds are consistent with the fits to the transverse flows of the radio scintillation signals.

Jeffrey L. Linsky; Barney J. Rickett; Seth Redfield

2007-11-07

116

Investigation of scintillator and fibre light in plastic scintillation dosimetry  

Microsoft Academic Search

Plastic scintillation dosimetry is a new and promising method of measuring dose in a radiation therapy beam. In this dosimetry system, the light signal produced in a miniature scintillator is transmitted to a photomultiplier tube via fiber optic cables. This system offers many advantages over conventional dosimetry methods, but an undesired radiation induced light signal is produced in the optical

Steven Francis Deboer

1993-01-01

117

Characteristics of ionospheric scintillation measured using GPS receivers onboard the COSMIC satellites  

NASA Astrophysics Data System (ADS)

GPS radio occultation and orbit determination receivers onboard six COSMIC satellites have been enabled to measure amplitude scintillation of the L-band signals. The measurements fill large gaps of spatial coverage, particularly over oceans, and significantly augment our capacity of measuring ionospheric irregularities from space. This paper presents an analysis of the scintillation data collected under low solar activity conditions during last few years. The long-term data collection over the globe helps to draw interesting characteristics, which are partially consistent with the known morphology of ionospheric scintillation obtained from ground-based measurements in different regions, but also different in many aspects. The differences are examined in detail to address ionospheric scintillation and irregularities measured from space compared with ground-based measurements. It is attempted in this analysis to derive a guide line to distinguish spaceborne and ground-based measurements of ionospheric scintillation.

Pi, X.; Mannucci, A. J.

2010-12-01

118

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

NASA Astrophysics Data System (ADS)

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

Priyadarshi, Shishir; Wernik, Andrzej W.

2013-10-01

119

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

SciTech Connect

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

Winter, B.; King, S. J.; Vallance, C., E-mail: claire.vallance@chem.ox.ac.uk [Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Rd, Oxford OX1 3TA (United Kingdom); Brouard, M., E-mail: mark.brouard@chem.ox.ac.uk [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Rd, Oxford OX1 3QZ (United Kingdom)

2014-02-15

120

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

121

An Air Core Scintillation Dosimeter for Megavoltage External Beam Dosimetry: Experimental Results  

Microsoft Academic Search

A plastic scintillation dosimeter, using an air core light guide to transport the scintillation signal, has been shown to\\u000a be free of the unwanted Cerenkov background signal that usually results from exposure of fibre optics to megavoltage photon\\u000a and electron radiation beams. We report the performance of the air core dosimeter in 6 MV and 18 MV photon beams and

J. Lambert; Y. Yin; D. R. McKenzie; S. Law; A. Ralston; N. Suchowerska

122

RECENT ADVANCES IN SCINTILLATION COUNTERS  

Microsoft Academic Search

Scintillation counters have allowed since the beginning a great variety ; of measurements due to the flexibility of their use. Numerous improvements have ; been made and they have presently a prominent place among radiation detectors. ; It is shown how, by technical improvements, in both laboratory and industry, the ; scintillation counter has become an instrument currently used in

Koechlin

1959-01-01

123

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

124

Lithium-loaded liquid scintillators  

DOEpatents

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

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

2012-05-15

125

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

126

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

127

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

128

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

Microsoft Academic Search

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

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

1996-01-01

129

Newborn Screening  

MedlinePLUS

... participate in the community. Home > Baby > Newborn screening Newborn screening Newborn screening checks for serious but rare ... been added to your dashboard . All babies get newborn screening Your baby gets newborn screening tests before ...

130

Computer model of high-latitude scintillation. [WBMOD program  

Microsoft Academic Search

The DNA Wideband satellite experiment provided extensive data on scintillation produced in high-altitude structured plasmas. A computer program, WBMOD, is being developed to summarize those data in an applications-oriented way. The program contains the phase-screen scattering theory of Rino and a morphological description of ionospheric irregularities (thus far only at auroral latitudes) based on Wideband observations. It permits a user

Fremouw

1982-01-01

131

A computer model of high-latitude scintillation  

Microsoft Academic Search

The DNA Wideband satellite experiment provided extensive data on scintillation produced in high-altitude structured plasmas. A computer program, WBMOD, is being developed to summarize those data in an applications-oriented way. The program contains the phase-screen scattering theory of Rino and a morphological description of ionospheric irregularities (thus far only at auroral latitudes) based on Wideband observations. It permits a user

E. J. Fremouw

1982-01-01

132

Empirical modelling of equatorial ionospheric scintillation  

Microsoft Academic Search

A computer-based model of ionospheric scintillations has been developed by Fremouw (socalled the WBMOD model) to give a mean scintillation index for a given set of observing conditions. The WBMOD model incorporates some of the scintillation observations made with the DNA wideband satellite. A comparison is made between the scintillation morphology observed at an equatorial station Ooty with the one

P. K. Pasricha; B. M. Reddy

1986-01-01

133

Proton recoil scintillator neutron rem meter  

DOEpatents

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

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

2003-01-01

134

Ionospheric scintillation studies  

NASA Technical Reports Server (NTRS)

The diffracted field of a monochromatic plane wave was characterized by two complex correlation functions. For a Gaussian complex field, these quantities suffice to completely define the statistics of the field. Thus, one can in principle calculate the statistics of any measurable quantity in terms of the model parameters. The best data fits were achieved for intensity statistics derived under the Gaussian statistics hypothesis. The signal structure that achieved the best fit was nearly invariant with scintillation level and irregularity source (ionosphere or solar wind). It was characterized by the fact that more than 80% of the scattered signal power is in phase quadrature with the undeviated or coherent signal component. Thus, the Gaussian-statistics hypothesis is both convenient and accurate for channel modeling work.

Rino, C. L.; Freemouw, E. J.

1973-01-01

135

Properties of scintillator solutes  

SciTech Connect

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

Fluornoy, J.M.

1998-06-01

136

Scintillator materials containing lanthanum fluorides  

DOEpatents

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

Moses, William W. (Berkeley, CA)

1991-01-01

137

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

138

Scintillator fiber optic long counter  

DOEpatents

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

McCollum, T.; Spector, G.B.

1994-03-29

139

Scintillator fiber optic long counter  

DOEpatents

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

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

1994-01-01

140

SNO+ Scintillator Purification and Assay  

Microsoft Academic Search

We describe the R&D on the scintillator purification and assay methods and technology for the SNO+ neutrino and double-beta decay experiment. The SNO+ experiment is a replacement of the SNO heavy water with liquid scintillator comprised of 2 g\\/L PPO in linear alkylbenzene (LAB). During filling the LAB will be transported underground by rail car and purified by multi-stage distillation

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

2011-01-01

141

SNO+ Scintillator Purification and Assay  

Microsoft Academic Search

We describe the R&D on the scintillator purification and assay methods and technology for the SNO+ neutrino and double-beta decay experiment. The SNO+ experiment is a replacement of the SNO heavy water with liquid scintillator comprised of 2 g?L PPO in linear alkylbenzene (LAB). During filling the LAB will be transported underground by rail car and purified by multi-stage distillation

R. Ford; M. Chen; O. Chkvorets; D. Hallman; E. Va´zquez-Ja´uregui

2011-01-01

142

AMIGA at the Auger Observatory: the scintillator module testing system  

NASA Astrophysics Data System (ADS)

AMIGA is an extension of the Pierre Auger Observatory that will consist of 85 detector pairs each one composed of a surface water-Cherenkov detector and a buried muon counter. Each muon counter has an area of 30 m2 and is made of scintillator strips with doped optical fibers glued to them, which guide the light to 64 pixels photomultiplier tubes. The detector pairs are arranged at 433 m and 750 m array spacings. In this paper we present the testing and initial calibration system for the scintillator modules that constitute each muon counter of AMIGA. The scintillator modules are tested with a "scanner" that consists of an x-y positioning system that moves a 5 mCi 137Cs radioactive source over the module taking data at fixed locations. The scanner both tests the module for possible fabrication defects and stores the light-attenuation curve parameters. A complete scanning process of a 64 strip scintillator module has been performed and results are presented. Also, attenuation curves obtained with scanner and with background muons are compared with satisfactory results.

Platino, M.; Hampel, M. R.; Almela, A.; Krieger, A.; Gorbeña, D.; Ferrero, A.; De La Vega, G.; Lucero, A.; Suarez, F.; Videla, M.; Wainberg, O.; Etchegoyen, A.

2011-06-01

143

Extruded plastic scintillator including inorganic powders  

DOEpatents

A method for producing a plastic scintillator is disclosed. A plurality of nano-sized particles and one or more dopants can be combined with a plastic material for the formation of a plastic scintillator thereof. The nano-sized particles, the dopant and the plastic material can be combined within the dry inert atmosphere of an extruder to produce a reaction that results in the formation of a plastic scintillator thereof and the deposition of energy within the plastic scintillator, such that the plastic scintillator produces light signifying the detection of a radiative element. The nano-sized particles can be treated with an inert gas prior to processing the nano-sized particles, the dopant and the plastic material utilizing the extruder. The plastic scintillator can be a neutron-sensitive scintillator, x-ray sensitive scintillator and/or a scintillator for the detection of minimum ionizing particles.

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

2006-06-27

144

Optimisation of nasal swab analysis by liquid scintillation counting.  

PubMed

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

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

2012-06-01

145

Scintillation light produced by low-energy beams of highly-charged ions  

E-print Network

Measurements have been performed of scintillation light intensities emitted from various inorganic scintillators irradiated with low-energy beams of highly-charged ions from an electron beam ion source (EBIS) and an electron cyclotron resonance ion source (ECRIS). Beams of xenon ions Xe$^{q+}$ with various charge states between $q$=2 and $q$=18 have been used at energies between 5 keV and 17.5 keV per charge generated by the ECRIS. The intensity of the beam was typically varied between 1 and 100 nA. Beams of highly charged residual gas ions have been produced by the EBIS at 4.5 keV per charge and with low intensities down to 100 pA. The scintillator materials used are flat screens of P46 YAG and P43 phosphor. In all cases, scintillation light emitted from the screen surface was detected by a CCD camera. The scintillation light intensity has been found to depend linearly on the kinetic ion energy per time deposited into the scintillator, while up to $q$=18 no significant contribution from the ions' potential e...

Vogel, M; Ernst, H; Zimmermann, H; Kester, O

2008-01-01

146

Scintillation light produced by low-energy beams of highly-charged ions  

NASA Astrophysics Data System (ADS)

Measurements have been performed of scintillation light intensities emitted from various inorganic scintillators irradiated with low-energy beams of highly-charged ions from an electron beam ion source (EBIS) and an electron cyclotron resonance ion source (ECRIS). Beams of xenon ions Xe q+ with various charge states between q = 2 and q = 18 have been used at energies between 5 and 17.5 keV per charge generated by the ECRIS. The intensity of the beam was typically varied between 1 and 100 nA. Beams of highly charged residual gas ions have been produced by the EBIS at 4.5 keV per charge and with low intensities down to 100 pA. The scintillator materials used are flat screens of P46 YAG and P43 phosphor. In all cases, scintillation light emitted from the screen surface was detected by a CCD camera. The scintillation light intensity has been found to depend linearly on the kinetic ion energy per time deposited into the scintillator, while up to q = 18 no significant contribution from the ions' potential energy was found. We discuss the results on the background of a possible use as beam diagnostics, e.g. for the new HITRAP facility at GSI, Germany.

Vogel, M.; Winters, D. F. A.; Ernst, H.; Zimmermann, H.; Kester, O.

2007-10-01

147

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

148

PMT calibration of a scintillation detector using primary scintillation  

NASA Astrophysics Data System (ADS)

We have studied the calibration of PMTs in scintillation detectors, inducing single electron response on the PMT from primary scintillation produced by x-ray interaction. The results agree with those obtained by the commonly used single electron response (SER) method, which uses LED light pulses to induce the PMT SER. The use of the primary scintillation for PMT calibration will be convenient in situations where the PMT is already in situ, when it becomes difficult or even impossible to apply the SER method, e.g. in commercial sealed scintillator/PMT devices. Furthermore, we have experimentally investigated the possibility of fitting the high-charge tail of the PMT SER pulse-height distribution to an exponential function, inferring the PMT gain from the inverse of the exponent. The results of the exponential fit method agree with those obtained by the SER method for pulse-height distributions resulting from an average number of around 1.0 photoelectrons reaching the first dynode per light/scintillation pulse. The SER method has higher precision and, therefore, is used in a larger number of applications. Nevertheless, the exponential fit method will be useful in situations where the single photoelectron peak is under the background or noise peak and it may present an alternative, simple way, for relative gain calibration of PMT arrays as well as for monitoring the PMT gain variations.

Freitas, E. D. C.; Fernandes, L. M. P.; Yahlali, N.; Pérez, J.; Álvarez, V.; Borges, F. I. G.; Camargo, M.; Cárcel, S.; Cebrián, S.; Cervera, A.; Conde, C. A. N.; Dafni, T.; Díaz, J.; Esteve, R.; Ferrario, P.; Ferreira, A. L.; Gehman, V. M.; Goldschmidt, A.; Gómez, H.; Gómez-Cadenas, J. J.; González Díaz, D.; Gutiérrez, R. M.; Hauptman, J.; Hernando Morata, J. A.; Herrera, D. C.; Irastorza, I. G.; Labarga, L.; Laing, A.; Liubarsky, I.; Lopez-March, N.; Lorca, D.; Losada, M.; Luzón, G.; Marí, A.; Martín-Albo, J.; Martínez, A.; Martínez Lema, G.; Miller, T.; Monrabal, F.; Monserrate, M.; Mora, F. J.; Moutinho, L. M.; Muñoz Vidal, J.; Nebot Guinot, M.; Nygren, D.; Oliveira, C. A. B.; Pérez, J.; Pérez Aparicio, J. L.; Querol, M.; Renner, J.; Ripoll, L.; Rodríguez, A.; Rodríguez, J.; Santos, F. P.; Dos Santos, J. M. F.; Seguí, L.; Serra, L.; Shuman, D.; Simón, A.; Sofka, C.; Sorel, M.; Toledo, J. F.; Torrent, J.; Tsamalaidze, Z.; Veloso, J. F. C. A.; Villar, J. A.; Webb, R.; White, J.; Monteiro, C. M. B.

2015-02-01

149

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

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

150

Structural design of a high energy particle detector using liquid scintillator  

SciTech Connect

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

Berg, Timothy John; /Minnesota U.

1997-02-01

151

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

152

Comprehensive renal scintillation procedures in spinal cord injury: comparison with excretory urography  

SciTech Connect

A /sup 131/iodine orthoiodohippurate comprehensive renal scintillation procedure was performed and compared to results of excretory urography in 200 spinal cord injury patients. No severe urographic abnormalities were undetected by the comprehensive renal scintillation procedure. Only 1.4 per cent of renal units had greater than minimal pyelocaliectasis or ureterectasis in the presence of a normal radionuclide examination. A relatively large number of abnormalities were detected on the renal scintillation procedure when the excretory urogram was normal. Serial followup will be required to determine the significance of these findings but present data suggest that a comprehensive renal scintillation procedure and a plain film of the kidneys, ureters and bladder may be used for screening upper urinary tract abnormalities in lieu of an excretory urogram. This is particularly advantageous for the spinal cord injury population, since there have been no toxic or allergic reactions reported, no bowel preparation or dehydration is required and there is relatively low radiation exposure.

Lloyd, L.K.; Dubovsky, E.V.; Bueschen, A.J.; Witten, D.M.; Scott, J.W.; Kuhlemeier, K.; Stover, S.L.

1981-07-01

153

CORISS Observations of Ionospheric Scintillation  

NASA Astrophysics Data System (ADS)

Rapid fluctuations in radio occultation (RO) signal to noise ratios and phase can signify the presence of fine scale ionospheric density irregularities along the occultation ray path. While such signatures are clearly identifiable in 1 Hz observations that are typically made at ionospheric tangent altitudes, high-rate (50 Hz) data is required to sample the full range of irregularity scale sizes responsible for L-band scintillation. At times the presence of intermediate-scale ionospheric structures can also be inferred from RO limb TEC and inverted electron density profiles, even when amplitude scintillations are not present. We present results of scintillation analysis of the first year of data from the CORISS instrument on the C/NOFS satellite, together with preliminary comparisons to scintillation data from overflights of the Air Force Research Laboratory’s ground-based SCINDA receivers that illustrate the characteristics of equatorial irregularities. Differences between scintillation indices derived from 1 Hz and 50 Hz observations will be discussed.

Straus, P. R.; Bishop, R. L.; Caton, R. G.; Groves, K. M.; Carrano, C. S.

2009-12-01

154

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

155

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

156

Scintillation at two optical frequencies.  

PubMed

Stellar scintillation data were obtained on a single night at a variety of zenith distances and azimuths, using a photon-counting photometer recording at 100 Hz simultaneously at wavelengths of 0.475 microm and 0.870 microm. Orientable apertures of 42-cm diam separated by 1 m were used to establish the average upper atmosphere wind direction and velocity. Dispersion in the earth's atmosphere separate the average optical paths at the two wavelengths, permitting a reconstruction of the spatial cross-correlation function for scintillations, independent of assumptions about differential fluid motions. Although there is clear evidence of a complicated velocity field, scintillation power was predominantly produced by levels at pressures of 130 +/- 30 mbar. The data are not grossly inconsistent with layers of isotropic Kolmogorov turbulence, but there is some evidence for deviation from the Kolmogorov spectral index and/or anisotropy. PMID:20333125

Hubbard, W B; Reitsema, H J

1981-09-15

157

Unitary scintillation detector and system  

DOEpatents

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

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

1994-05-31

158

Interstellar scintillations of pulsar radiation.  

PubMed

Time fluctuations in the intensity of pulsed radiation from CP 0834, CP 1133, AP 1237, and CP 1919 have been investigated. Power spectra, modulation indices, frequency distributions, and decorrelation frequencies are consistent with scintillation theory. If it is assumed that these scintillations are due to irregularities in the interstellar medium that travel at a velocity of 20 kilometers per second, the irregularities have a scale size on the order of 10(4) kilometers and a distance from the earth of approximately 70 parsecs. These interstellar scintillations would not have been observed if the apparent angular diameters of the pulsars were larger than 0.3 X 10(-5) second of arc, and they would cause even a point radio source to have an apparent angular diameter of approximately 10(-3) second of arc at 318 megahertz. PMID:17744967

Lang, K R

1969-12-12

159

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

160

Fracture-resistant lanthanide scintillators  

DOEpatents

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

Doty, F. Patrick (Livermore, CA)

2011-01-04

161

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

162

Artistic screening  

Microsoft Academic Search

Artistic screening is a new image reproduction technique incorpo- rating freely created artistic screen elements for generating halftones. Fixed predefined dot contours associated with given intensity lev- els determine the screen dot shape's growing behavior. Screen dot contours associated with each intensity level are obtained by inter- polation between the fixed predefined dot contours. A user-defined mapping transforms screen elements

Victor Ostromoukhov; Roger D. Hersch

1995-01-01

163

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

164

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

165

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

166

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

167

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

168

THE ORIGIN OF RADIO SCINTILLATION IN THE LOCAL INTERSTELLAR MEDIUM Jeffrey L. Linsky,1  

E-print Network

and annual scintillation variability produced by the Earth's motion relative to turbulent-scattering screens flow vectors of these clouds, we find that the relative radial and transverse velocities. For all three sight lines the flow velocities of nearby warm local interstellar clouds are consistent

Royer, Dana

169

LSO-Based Single Crystal Film Scintillator for Synchrotron-Based Hard X-Ray Micro-Imaging  

Microsoft Academic Search

X-ray detector systems are powerful tools: in combination with tomographic methods they provide volumetric data of samples in a non-destructive manner which is of high interest for, e.g., biology, medicine or materials research. The detector able to provide images with submicrometer spatial resolution frequently consists of a scintillator screen, light microscopy optics and a digital camera. Here, the scintillator converts

Thierry Martin; Paul-Antoine Douissard; Maurice Couchaud; Angelica Cecilia; Tilo Baumbach; Klaus Dupre; Alexander Rack

2009-01-01

170

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

171

A mid-latitude scintillation model  

Microsoft Academic Search

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

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

1986-01-01

172

Ionospheric scintillations at L & C bands  

Microsoft Academic Search

This paper addresses the problem of ionospheric scintillations at L and C bands. The results of a L band scintillation measurement campaign are presented. The receivers used during this campaign were located in the five regions of the globe allowing to exhibit latitudinal and longitudinal dependence. Comparison with modeling has been done concurrently. The results presented for C band scintillations

Yannick Béniguel; J.-P. Adam; R. Prieto-Cerdeira; B. Arbesser-Rastburg

2009-01-01

173

Synthesis of plastic scintillation microspheres: Evaluation of scintillators  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

174

Scintillating fiber ribbon --- tungsten calorimeter  

SciTech Connect

We describe an ultra-high density scintillating fiber and tungsten calorimeter used as an active beam-dump for electrons. Data showing the calorimeter response to electrons with momenta between 50 and 350 GeV/c are presented. 9 figs.

Bross, A.; Crisler, M.; Kross, B.; Wrbanek, J.

1989-07-14

175

Photodetectors for scintillator proportionality measurement  

Microsoft Academic Search

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

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

2009-01-01

176

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

177

Extruded plastic scintillator for MINERvA  

SciTech Connect

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

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

2005-11-01

178

Speeding up Directed Evolution: Combining the Advantages of Solid-Phase Combinatorial Gene Synthesis with Statistically Guided Reduction of Screening Effort.  

PubMed

Efficient and economic methods in directed evolution at the protein, metabolic, and genome level are needed for biocatalyst development and the success of synthetic biology. In contrast to random strategies, semirational approaches such as saturation mutagenesis explore the sequence space in a focused manner. Although several combinatorial libraries based on saturation mutagenesis have been reported using solid-phase gene synthesis, direct comparison with traditional PCR-based methods is currently lacking. In this work, we compare combinatorial protein libraries created in-house via PCR versus those generated by commercial solid-phase gene synthesis. Using descriptive statistics and probabilistic distributions on amino acid occurrence frequencies, the quality of the libraries was assessed and compared, revealing that the outsourced libraries are characterized by less bias and outliers than the PCR-based ones. Afterward, we screened all libraries following a traditional algorithm for almost complete library coverage and compared this approach with an emergent statistical concept suggesting screening a lower portion of the protein sequence space. Upon analyzing the biocatalytic landscapes and best hits of all combinatorial libraries, we show that the screening effort could have been reduced in all cases by more than 50%, while still finding at least one of the best mutants. PMID:24921161

Hoebenreich, Sabrina; Zilly, Felipe E; Acevedo-Rocha, Carlos G; Zilly, Matías; Reetz, Manfred T

2015-03-20

179

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

180

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

181

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

182

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

183

Boron layer scintillation neutron detectors  

Microsoft Academic Search

Summary  Neutron detection with layers of crystalline powder mixtures of a boron compound and of a scintillator, used in connection\\u000a with a photomultiplier, has been studied. Efficiency of 6% for incident thermal neutrons and almost complete insensitivity\\u000a to ? and cosmic rays is reached. Detector's geometry approaches that of an infinitely thin sheet. Pulses may be shaped so\\u000a as to have

E. Gatti; E. Germagnoli; A. Persano; E. Zimmer

1952-01-01

184

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

2015-02-01

185

A Review of Ionospheric Scintillation Models  

NASA Astrophysics Data System (ADS)

This is a general review of the existing climatological models of ionospheric radio scintillation for high and equatorial latitudes. Trans-ionospheric communication of radio waves from transmitter to user is affected by the ionosphere which is highly variable and dynamic in both time and space. Scintillation is the term given to irregular amplitude and phase fluctuations of the received signals and related to the electron density irregularities in the ionosphere. Key sources of ionospheric irregularities are plasma instabilities; every irregularities model is based on the theory of radio wave propagation in random media. It is important to understand scintillation phenomena and the approach of different theories. Therefore, we have briefly discussed the theories that are used to interpret ionospheric scintillation data. The global morphology of ionospheric scintillation is also discussed briefly. The most important (in our opinion) analytical and physical models of scintillation are reviewed here.

Priyadarshi, S.

2015-01-01

186

A Review of Ionospheric Scintillation Models  

NASA Astrophysics Data System (ADS)

This is a general review of the existing climatological models of ionospheric radio scintillation for high and equatorial latitudes. Trans-ionospheric communication of radio waves from transmitter to user is affected by the ionosphere which is highly variable and dynamic in both time and space. Scintillation is the term given to irregular amplitude and phase fluctuations of the received signals and related to the electron density irregularities in the ionosphere. Key sources of ionospheric irregularities are plasma instabilities; every irregularities model is based on the theory of radio wave propagation in random media. It is important to understand scintillation phenomena and the approach of different theories. Therefore, we have briefly discussed the theories that are used to interpret ionospheric scintillation data. The global morphology of ionospheric scintillation is also discussed briefly. The most important (in our opinion) analytical and physical models of scintillation are reviewed here.

Priyadarshi, S.

2015-03-01

187

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

188

Longitudinal correlation of equatorial ionospheric scintillation  

Microsoft Academic Search

Studies at the Air Force Research Laboratory are investigating methods for the incorporation of expected data sets from the Communication\\/Navigation Outage Forecast System (C\\/NOFS) satellite into existing scintillation specification models for an improved knowledge of the regional scintillation environment. Results from this research will form the basis for ground-based empirical scintillation forecast algorithms. One such study involves a determination of

Ron Caton; Keith Groves

2006-01-01

189

Structure-guided design of fluorescent S-adenosylmethionine analogs for a high-throughput screen to target SAM-I riboswitch RNAs  

PubMed Central

Summary Many classes of S-adenosylmethionine (SAM)-binding RNAs and proteins are of interest as potential drug targets in diverse therapeutic areas, from infectious diseases to cancer. In the former case, the SAM-I riboswitch is an attractive target because this structured RNA element is found only in bacterial mRNAs and regulates multiple genes in several human pathogens. Here we describe the synthesis of stable and fluorescent analogs of SAM in which the fluorophore is introduced through a functionalizable linker to the ribose. A Cy5-labeled SAM analog was shown to bind several SAM-I riboswitches via in-line probing and fluorescence polarization (FP) assays, including one from Staphylococcus aureus that controls the expression of SAM synthetase in this organism. A fluorescent ligand displacement assay was developed and validated for high-throughput screening of compounds to target the SAM-I riboswitch class. PMID:24560607

Hickey, Scott F.; Hammond, Ming C.

2014-01-01

190

Divalent fluoride doped cerium fluoride scintillator  

DOEpatents

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

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

1991-01-01

191

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

192

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

193

Health Screening  

MedlinePLUS

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

194

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 ...

195

21 CFR 892.1100 - Scintillation (gamma) camera.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Scintillation (gamma) camera. 892.1100 Section 892.1100 Food... § 892.1100 Scintillation (gamma) camera. (a) Identification. A scintillation (gamma) camera is a device intended to image...

2010-04-01

196

Chemical compatibility screening test results  

SciTech Connect

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

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

1997-12-01

197

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

198

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

199

Separation and purification of ?-glucosidase inhibitors from Polygonatum odoratum by stepwise high-speed counter-current chromatography combined with Sephadex LH-20 chromatography target-guided by ultrafiltration-HPLC screening.  

PubMed

Although Polygonatum odoratum has been widely used as medicinal plant and food supplement for treating diabetes, little is known regarding its bioactive components. In this study, ultrafiltration-HPLC based ligand screening was developed to screen ?-glucosidase inhibitors from P. odoratum for the first time. Then bioactive components were target-guided separated by combining stepwise high-speed counter-current chromatography (HSCCC) using petroleum ether-ethyl acetate-methanol-water (1:4:0.8:4.2, v/v/v/v), (1:4:1.8:3.2, v/v/v/v) and (1:4:2.3:2.7, v/v/v/v) as solvent systems with Sephadex LH-20 chromatography eluted by MeCN-MeOH (1:1, v/v). Five phenethyl cinnamides, N-cis-feruloyloctopamine (1); N-trans-p-coumaroyloctopamine (2), N-trans-feruloyloctopamine (3), N-trans-p-coumaroyltyramine (4) and N-trans-feruloyltyramine (5), and four homoisoflavanones, (3R)-5,7-dihydroxyl-3-(2',4'-dihydroxylbenzyl)-chroman-4-one (6), (3R)-5,7-dihydroxyl-6-methyl-3-(4'-hydroxylbenzyl)-chroman-4-one (7), (3R)-5,7-dihydroxyl-6-methyl-8-methoxyl-3-(4'-hydroxylbenzyl)-chroman-4-one (8); and (3R)-5,7-dihydroxyl-6,8-dimethyl-3-(4'-hydroxylbenzyl)-chroman-4-one) (9), with purity over 98.5% were purified, and their structures were identified by UV, MS, and (1)H NMR. Notably, compounds 2 and 4 were first reported in genus Polygonatum, while compound 1 was first obtained from family Liliaceae. In addition, ?-glucosidase inhibitory activities of compounds 1-9 were evaluated, and compounds 2 and 4 exhibited stronger ?-glucosidase inhibitory activity with IC50 values of 2.3 and 2.7?M. The results suggested the potential medicinal use of P. odoratum, and the technology could be widely applied for rapid screening and preparative separation of a group of bioactive compounds from complex matrix. PMID:25682336

Zhou, Xiaoling; Liang, Junsheng; Zhang, Yi; Zhao, Huading; Guo, Ying; Shi, Shuyun

2015-03-15

200

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

201

A homogeneous scintillation proximity assay for acetyl coenzyme A carboxylase coupled to fatty acid synthase.  

PubMed

We have devised a rapid and sensitive homogeneous assay for acetyl CoA carboxylase (ACC) in a scintillation proximity assay format suitable for high-throughput screening. In this assay, ACC is coupled to fatty acid synthase (FAS). Malonyl CoA, the product of the ACC reaction, and acetyl CoA serve as substrates for FAS to synthesize palmitic acid. When [(3)H]acetyl CoA is used in the ACC/FAS coupled system, [(3)H]palmitic acid, the final product, is readily detected by scintillation proximity in a FlashPlate or Image FlashPlate coated with phospholipid. The [(3)H]palmitic acid binds to the coated phospholipid through hydrophobic interaction which brings it into close proximity of the scintillant on the FlashPlate or the Image FlashPlate, yielding photons that are read in a TopCount or LeadSeeker, respectively. The current assay consists of simple reagent addition, incubation, and detection of signal. The signal is approximately 30-fold over the background and the Z' value is approximately 0.80, suggesting that this assay is robust and highly reproducible. To our knowledge this ACC/FAS coupled scintillation proximity assay is the only assay format that is compatible with high-throughput screening for systematic search of inhibitors against mammalian ACC. PMID:16996019

Seethala, Ramakrishna; Ma, Zhengping; Golla, Rajasree; Cheng, Dong

2006-11-15

202

Scintillator handbook with emphasis on cesium iodide  

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

203

Ionosphere scintillation effects on navigation systems  

NASA Astrophysics Data System (ADS)

This article deals with the impact of ionospheric electron density inhomogeneities on the functionality of global navigation satellite systems emphasizing positioning errors. The scintillation characteristics of transmitted signals have been obtained using data gathered in measurement campaigns. The effects on a standard receiver are then presented. Positioning errors due to scintillations were shown to be greater than 10 meters in the worst case.

Béniguel, Yannick; Adam, Jean-Pierre; Bourdillon, Alain; Lassudrie-Duchesne, P.

2011-03-01

204

Optimum scintillator thickness for beta dosimetry  

Microsoft Academic Search

Beta particle counting by plastic scintillation counter is a convenient method of determining the beta dose rate from the natural radioactivity in soils, as required for example in the process of luminescence dating of sediments or sherds. Data is presented to establish the optimum thickness of plastic scintillator for such beta dosimetry, found to be about 6 mm.

R. B. Galloway

1994-01-01

205

Scintillation modeling using in situ data  

Microsoft Academic Search

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

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

2007-01-01

206

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

207

A study of scintillation beta microprobes  

Microsoft Academic Search

Several types of scintillation microprobes have recently been developed to directly measure positron activity from radiotracers in live animals. These probes consist of either a small lutetium oxyorthosilicate (LSO) crystal or plastic scintillator coupled to an optical fiber that is read out with a photomultiplier tube operated in a single photon counting mode. In this paper, a comparison is made

C. L. Woody; S. P. Stoll; D. J. Schlyer; M. Gerasimov; P. Vaska; S. Shokouhi; N. Volkow; J. S. Fowler; S. L. Dewey

2002-01-01

208

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

PubMed Central

Aims: Pathologists are under increasing pressure to accurately subclassify sarcomas, yet neuropathologists have limited collective experience with rare sarcoma types such as synovial sarcoma. We reviewed 9 synovial sarcomas affecting peripheral nerve diagnosed by neuropathologists and explored the morphologic and immunohistochemical differences between these and MPNST. Our goal was to make practical recommendations for neuropathologists regarding which spindle cell tumors affecting nerve should be sent for SYT-SSX testing. Methods: Clinical records and genetics were reviewed retrospectively and central pathology review of 9 synovial sarcomas and 6 MPNST included immunohistochemistry for SOX10, S100, BAF47, CK (lmw, pan, CK7, CK19), EMA, CD34, bcl2, CD99, and neurofilament. Results: Common synovial sarcoma sites were brachial plexus, spinal and femoral nerve, none were “intra-neural”, all had the SYT-SSX1 translocation, and 6/9 were monophasic with myxoid stroma and distinct collagen. Half of the monophasic synovial sarcomas expressed CK7, CK19 or panCK in a “rare positive cells pattern”, 8/9 (89%) expressed EMA, and all were SOX10 immunonegative with reduced but variable BAF47 expression. Conclusions: We recommend that upon encountering a cellular spindle cell tumor affecting nerve neuropathologists consider the following: 1) SYT-SSX testing should be performed on any case with morphology suspicious for monophasic synovial sarcoma including wiry or thick bands of collagen and relatively monomorphous nuclei; 2) neuropathologists should employ a screening immunohistochemical panel including one of CK7, panCK or CK19, plus EMA, S100 and SOX10, and 3) SYT-SSX testing should be performed on any spindle cell tumor with CK and/or EMA immunopositivity if SOX10 immunostaining is negative or only labels entrapped nerve elements. PMID:24131748

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

2013-01-01

209

Interstellar scattering of pulsar radiation. 1: Scintillation  

NASA Technical Reports Server (NTRS)

An investigation of the intensity fluctuations of 28 pulsars near 0.4 GHz indicates that scintillation spectra have a Gaussian shape, scintillation indices are near unity, and the scintillation bandwidth depends linearly on dispersion measure. Observations near 2.5 GHz suggest a strong dependence of the frequency at which scintillation indices fall below unity on dispersion measure. Multistation measurements of scintillation provide values or limits for the scale size of the scattering diffraction pattern. The dependences of scattering parameters on dispersion measure is discussed in terms of the current models. It is suggested that any line of sight through the galaxy encounters increasingly rare, increasingly large deviations of thermal electron density on the scale of 10 to the 11th power cm.

Backer, D. C.

1974-01-01

210

Empirical modelling of equatorial ionospheric scintillation  

NASA Astrophysics Data System (ADS)

A computer-based model of ionospheric scintillations has been developed by Fremouw (socalled the WBMOD model) to give a mean scintillation index for a given set of observing conditions. The WBMOD model incorporates some of the scintillation observations made with the DNA wideband satellite. A comparison is made between the scintillation morphology observed at an equatorial station Ooty with the one evolved with the WBMOD model. Morphological features at other stations in the equatorial region are briefly described. The WBMOD model predicts the pre-midnight maximum seen at the Indian longitudes. The seasonal pattern reproduced by the model incorporates longitudinal variability. The solar activity dependence in the model seems to be rather high. Empirical expressions giving the dependence of scintillation index on morphological parameters are obtained

Pasricha, P. K.; Reddy, B. M.

1986-06-01

211

Scintillation Effects on Space Shuttle GPS Data  

NASA Technical Reports Server (NTRS)

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

Goodman, John L.; Kramer, Leonard

2001-01-01

212

Lindblad equation for the decay of entanglement due to atmospheric scintillation  

E-print Network

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

Filippus S. Roux

2014-04-08

213

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.

214

Effects of ionospheric scintillation on Transit satellite measurement of total electron content  

Microsoft Academic Search

Ionospheric scintillation can affect not only satellite communications but also satellite measurements of the ionosphere, such as the measurements of total electron content (TEC) made using Transit-like signal transmissions. In this work a numerical phase-screen propagation simulation is applied to study the accuracy of the measurement of TEC made with Transit-like signals. To measure TEC, the phase from coherently related

D. L. Knepp

2004-01-01

215

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

SciTech Connect

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

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

2011-01-01

216

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

217

Scintillating fiber camera for neutron dosimetry in spacecraft  

Microsoft Academic Search

A scintillating fiber camera for three-dimensional imaging was newly developed for radiation dosimetry in spacecraft. The camera consists of a scintillating fiber stack, an image intensifier unit and photomultipliers for triggering events. The scintillating fiber stack has 100 scintillating fiber layers. The layers are alternatively stacked up to be perpendicular to each other. The stack is coupled to a two-stage

K. Terasawa; T. Doke; N. Hasebe; J. Kikuchi; K. Kudo; T. Murakami; N. Takeda; T. Tamura; S. Torii; M. Yamashita; E. Yoshihira

2001-01-01

218

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

219

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

220

Newborn screening.  

PubMed

The aim of newborn screening is to detect newborns with serious, treatable disorders so as to facilitate appropriate interventions to avoid or ameliorate adverse outcomes. Mass biochemical testing of newborn babies was pioneered in the 1960s with the introduction of screening for phenylketonuria, a rare inborn error of metabolism, tested by using a dried blood spot sample. The next disorder introduced into screening programs was congenital hypothyroidism and a few more much rarer disorders were gradually included. Two recent advances have greatly changed the pace: modification of tandem mass spectrometry and DNA extraction and analysis from newborn screening dried blood spot. These two technologies make the future possibilities of newborn screening seem almost unlimited. Newborn screening tests are usually carried out on a dried blood spot sample, for which there are special analytical considerations. Dried blood spot calibrators and controls, prepared on the same lot number of filter paper, are needed. Methods have a co-efficient of variation of about 10% due to the increased variability of a dried filter paper sample compared with other biochemical samples. The haematocrit is an additional variable not able to be measured. Also of importance is obtaining a balance between the sensitivity and specificity of each assay. Fixing cut-off points for action needs consideration of what is an acceptable percentage of the population to recall for further testing. Few assays are 100% discriminatory. Programs in Australasia currently screen for at least 30 disorders. Detection of these requires not only the assay of a primary marker but often determination of a ratio of that marker with another, or possibly an alternative assay, for example a DNA mutation. The most important disorders screened for are described briefly: phenylketonuria, primary congenital hypothyroidism, cystic fibrosis, the galactosaemias, medium-chain acyl-CoA dehydrogenase deficiency, glutaryl-CoA dehydrogenase deficiency and congenital adrenal hyperplasia, together with several other disorders detectable by tandem mass spectrometry. Newborn screening deals with rare disorders and benefit cannot be shown easily without very large pilot studies. There have been randomised controlled trials of screening for cystic fibrosis, and now several studies are beginning to establish the benefit of tandem mass spectrometry screening for disorders of fatty acid and amino acid metabolism. Two things will influence the new directions for newborn screening: the development of effective treatments for hitherto untreatable disorders, and advancing technology, enabling new testing strategies to be developed. There are novel treatments on the horizon for many discrete disorders. Susceptibility testing has recently been considered for newborn screening application, but is more controversial. Newborn screening has entered a new and exciting phase, with an explosion of new treatments, new technologies, and, possibly in the future, new preventive strategies. PMID:18203033

Wilcken, Bridget; Wiley, Veronica

2008-02-01

221

A computer model for high-latitude phase scintillation based on wideband satellite data from Poker Flat  

NASA Astrophysics Data System (ADS)

A mathematical model has been developed for describing plasma-density irregularities responsible for radiowave scintillation produced in the auroral ionosphere, and the model has been committed to an applications-oriented computer code, WBMOD. The model characterizes the three-dimensional configuration, gradient sharpness, and height-integrated strength of irregularities represented by a power-law spatial spectrum as functions of geomagnetic latitude, time of day, sunspot number, and planetary geomagnetic activity index. Program WBMOD permits calculation of the power-law index and spectral strength (at a fluctuation frequency of 1 Hz) of phase scintillation, together with scintillation indices (variances) for phase and intensity, using a phase-screen scattering theory. The model has been calibrated and iteratively tested against phase-scintillation data from the DNA Wideband Satellite Experiment, collected at Poker Flat, Alaska. It does not account for seasonal variations in high-latitude scintillation observed in other longitude sectors. The program contains a model for middle-latitude and equatorial irregularities as well as for auroral latitudes, but only the latter has been tested extensively against high-quality scintillation data.

Fremouw, E. J.; Lansinger, J. M.

1981-02-01

222

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.

2012-06-26

223

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

224

Long wavelength scintillators for fiber-optic applications  

SciTech Connect

The use of fiber optics in plasma diagnostics has spurred the development of long wavelength scintillators with fast temporal characteristics. In this paper we describe several new liquid scintillator systems with fluorescent emissions maxima up to 730 nm. Subnanosecond scintillator FWHM response times have been obtained by the operation of liquid scintillators at elevated temperatures. Data on fiber system sensitivity versus fiber length and scintillator emission wavelength will be presented.

Lyons, P.B.; Franks, L.; Lutz, S.; Flournoy, J.; Fullman, E.

1980-01-01

225

Touchplates: Low-Cost Tactile Overlays for Visually Impaired Touch Screen Users  

E-print Network

designed tactile guides that provide tactile feedback for touch screens in the form of physical guidesTouchplates: Low-Cost Tactile Overlays for Visually Impaired Touch Screen Users Shaun K. Kane UMBC feedback to touch screens can improve their accessibility to blind users, but prior approaches

Kane, Shaun K.

226

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

PubMed

A two-dimensional position sensitive dosimetry system based on a scintillating gas detector has been developed for pre-treatment verification of dose distributions in hadron therapy. The dosimetry system consists of a chamber filled with an Ar/CF4 scintillating gas mixture, inside which two cascaded gas electron multipliers (GEMs) are mounted. A GEM is a thin kapton foil with copper cladding structured with a regular pattern of sub-mm holes. The primary electrons, created in the detector's sensitive volume by the incoming beam, drift in an electric field towards the GEMs and undergo gas multiplication in the GEM holes. During this process, photons are emitted by the excited Ar/CF4 gas molecules and detected by a mirror-lens-CCD camera system. Since the amount of emitted light is proportional to the dose deposited in the sensitive volume of the detector by the incoming beam, the intensity distribution of the measured light spot is proportional to the 2D hadron dose distribution. For a measurement of a 3D dose distribution, the scintillating gas detector is mounted at the beam exit side of a water-bellows phantom, whose thickness can be varied in steps. In this work, the energy dependence of the output signal of the scintillating gas detector has been verified in a 250 MeV/u clinical 12C ion beam by means of a depth-dose curve measurement. The underestimation of the measured signal at the Bragg peak depth is only 9% with respect to an air-filled ionization chamber. This is much smaller than the underestimation found for a scintillating Gd2O2S:Tb ('Lanex') screen under the same measurement conditions (43%). Consequently, the scintillating gas detector is a promising device for verifying dose distributions in high LET beams, for example to check hadron therapy treatment plans which comprise beams with different energies. PMID:18695295

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

2008-09-01

227

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

PubMed Central

Thick, segmented scintillating detectors, consisting of 2D matrices of scintillator crystals separated by optically opaque septal walls, hold considerable potential for significantly improving the performance of megavoltage (MV) active matrix, flat-panel imagers (AMFPIs). Initial simulation studies of the radiation transport properties of segmented detectors have indicated the possibility of significant improvement in DQE compared to conventional MV AMFPIs based on phosphor screen detectors. It is therefore interesting to investigate how the generation and transport of secondary optical photons affect the DQE performance of such segmented detectors. One effect that can degrade DQE performance is optical Swank noise (quantified by the optical Swank factor Iopt), which is induced by depth-dependent variations in optical gain. In this study, Monte Carlo simulations of radiation and optical transport have been used to examine Iopt and zero-frequency DQE for segmented CsI:Tl and BGO detectors at different thicknesses and element-to-element pitches. For these detectors, Iopt and DQE were studied as a function of various optical parameters, including absorption and scattering in the scintillator, absorption at the top reflector and septal walls, as well as scattering at the side surfaces of the scintillator crystals. The results indicate that Iopt and DQE are only weakly affected by absorption and scattering in the scintillator, as well as by absorption at the top reflector. However, in some cases, these metrics were found to be significantly degraded by absorption at the septal walls and scattering at the scintillator side surfaces. Moreover, such degradations are more significant for detectors with greater thickness or smaller element pitch. At 1.016 mm pitch and with optimized optical properties, 40 mm thick segmented CsI:Tl and BGO detectors are predicted to provide DQE values of ?29% and 42%, corresponding to improvement by factors of ?29 and 42, respectively, compared to that of conventional MV AMFPIs. PMID:19673222

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

2009-01-01

228

Scintillation gamma spectrometer for analysis of hydraulic fracturing waste products.  

PubMed

Flowback and produced wastewaters from unconventional hydraulic fracturing during oil and gas explorations typically brings to the surface Naturally Occurring Radioactive Materials (NORM), predominantly radioisotopes from the U238 and Th232 decay chains. Traditionally, radiological sampling are performed by sending collected small samples for laboratory tests either by radiochemical analysis or measurements by a high-resolution High-Purity Germanium (HPGe) gamma spectrometer. One of the main isotopes of concern is Ra226 which requires an extended 21-days quantification period to allow for full secular equilibrium to be established for the alpha counting of its progeny daughter Rn222. Field trials of a sodium iodide (NaI) scintillation detector offers a more economic solution for rapid screenings of radiological samples. To achieve the quantification accuracy, this gamma spectrometer must be efficiency calibrated with known standard sources prior to field deployments to analyze the radioactivity concentrations in hydraulic fracturing waste products. PMID:25734826

Ying, Leong; O'Connor, Frank; Stolz, John F

2015-04-16

229

Liquid Scintillator Time Projection Chamber Concept  

E-print Network

Results are presented from a small-scale experiment to investigate the use of room temperature organic liquid scintillators as the active medium for a time projection chamber (TPC). The optical properties of liquid scintillators have long been known, but their ability to transport charge has remained, until now, largely untested. The idea of using room temperature liquids as an active medium for an ionisation chamber was first presented in \\cite{EnglerTMS}. Since then the range of liquid scintillators available has been greatly developed. We present successful transport of ionization charges in a selection of both, pure organic liquid solvents and liquid scintillator cocktails over 20$\\,$mm using a variety of electric drift field strengths. The target of this research is to offer a cost effective alternative to liquid noble gas detectors in neutrino physics.

McConkey, N

2012-01-01

230

Study of rare-earth-doped scintillators  

NASA Astrophysics Data System (ADS)

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

Yanagida, Takayuki

2013-09-01

231

The Calice Scintillator HCAL Testbeam Prototype  

NASA Astrophysics Data System (ADS)

A highly-granular, 38-layer, analog scintillator-tile hadron calorimeter prototype is under construction by members of the Calice collaboration in order to study hadronic shower shapes and to test the calorimetric aspects of particle-flow.

Eigen, Gerald

2006-10-01

232

Liquid scintillators for optical fiber applications  

SciTech Connect

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

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

1982-01-01

233

Liquid scintillators for optical fiber applications  

SciTech Connect

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

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

1982-11-16

234

EAS transient effect in thick scintillators  

NASA Astrophysics Data System (ADS)

The transient effect in extensive air showers was investigated using the thick (30 cm) liquid scintillators of the Kover device at the Baksan neutrino observatory. The data were interpreted in the light of the total transient effect, consisting in the ratio of the density of particles recorded in the scintillator to the density of particles above the concrete roof of the facility. The results are compared with those of a computer-simulation program for electron-photon cascades.

Lidvanskii, A. S.; Navarra, Dzh.; Cherniaev, A. B.

1985-07-01

235

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

236

Evaluation of clad scintillating light pipes  

NASA Technical Reports Server (NTRS)

Arrays of fibers made of scintillating material were used as position-sensitive detectors or hodoscopes for beam-finding at ion accelerators. Experiments were made with alpha's from an Am241 source incident upon one end of the fiber, the other end being viewed with a photomultiplier tube. The scintillation light was not detected in any of the fibers tested beyond about 5 cm. The effective useful lengths for detection of relativistic heavy ions were given.

1976-01-01

237

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

238

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

239

Cerium fluoride, a new fast, heavy scintillator  

Microsoft Academic Search

The authors describe the scintillation properties of Cerium Fluoride (CeFâ), a newly discovered, heavy (6.16 g\\/cm³), inorganic scintillator. Its fluorescence decay lifetime, measured with the delayed coincidence method, is described by a single exponential with a 27 +- 1 ns time constant. The emission spectrum peaks at a wavelength of 340 nm, and drops to less than 10% of its

W. W. Moses; S. E. Derenzo

1989-01-01

240

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

241

A gamma-ray discriminating neutron scintillator  

SciTech Connect

A neutron scintillator has been developed at Pacific Northwest Laboratory which responds directly to as little as 10 mrem/hour dose equivalent rate fast neutron fields. The scintillator is composed of CaF{sub 2}:Eu or of NaI grains within a silicone rubber or polystyrene matrix, respectively. Neutrons colliding with the plastic matrix provide knockon protons, which in turn deposit energy within the grains of phosphor to produce pulses of light. Neutron interactions are discriminated from gamma-ray events on the basis of pulse height. Unlike NE-213 liquid scintillators, this solid scintillator requires no pulseshape discrimination and therefore requires less hardware. Neutron events are anywhere from two to three times larger than the gamma-ray exposures are compared to 0.7 MeV gamma-ray exposures. The CaF{sub 2}:Eu/silicone rubber scintillator is nearly optically transparent, and can be made into a very sizable detector (4 cm x 1.5 cm) without degrading pulse height. This CaF{sub 2}:Eu scintillator has been observed to have an absolute efficiency of 0.1% when exposed to 5-MeV accelerator-generated neutrons (where the absolute efficiency is the ratio of observed neutron events divided by the number of fast neutrons striking the detector).

Eschbach, P.A.; Miller, S.D.; Cole, M.C. [Pacific Northwest Lab., Richland, WA (United States)] [and others

1994-12-31

242

Airport Screening  

MedlinePLUS

... cannot become radioactive from this procedure. However, some photographic film may need to be hand-screened because ... professional organization whose mission is excellence in the science and practice of radiation safety. Formed in 1956, ...

243

MRSA Screening  

MedlinePLUS

... in a molecular test, but the specimen is analyzed for the genetic markers to identify S. aureus and ... Skin Infections In the News: MRSA Prevention Strategies Analyzed, Screening Policies Challenged (2013) Elsewhere On The Web ...

244

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 ...

245

Developmental Screening  

MedlinePLUS

Developmental Screening FACT SHEET What is child development? A child’s growth is more than just physical. Children grow, develop, and learn throughout their lives, starting at birth. A child’s development can be followed ...

246

Mid-latitude scintillation model. Technical report, 1 November 1985-31 October 1986  

SciTech Connect

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, R.E.; Secan, J.A.; Fremouw, E.J.

1986-10-31

247

Equatorial scintillation model. Technical report, 1 February 1983-30 April 1985  

SciTech Connect

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 is 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.

1985-09-30

248

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

E-print Network

SFT 1SFT 1 SFT 2SFT 2 Weilin Yu, DPG Frühjahrstagung,Gießen #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

249

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

SciTech Connect

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

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

1984-01-01

250

Career Guide to Industries  

NSDL National Science Digital Library

A companion to the Occupational Outlook Handbook 2000-2001 (See the April 14, 2000 Scout Report), the Career Guide to Industries "provides information on available careers by industry, including the nature of the industry, working conditions, employment, occupations in the industry, training and advancement, earnings and benefits, employment outlook, and lists of organizations that can provide additional information." While the Occupational Outlook Handbook focuses on specific careers, this guide considers industries in a broader scope, examining 47 industries. The industries are broken into seven sectors, each containing several overviews. Each career guide includes the same sections: Significant Points, Nature of the Industry, Working Conditions, Employment Occupations in the Industry, Training and Advancement, Earnings Outlook, and Sources of Additional Information. Users may search for a specific industry using the key word search feature on the top right of the screen.

251

Electron Screening  

NASA Astrophysics Data System (ADS)

Understanding the electron screening effect in the laboratory is critical for a correct interpretation of low-energy nuclear reactions in stars. The theory of electron screening in a stellar plasma is still based on the physics model introduced in 1954 by Salpeter, although the mathematical treatments have been improved significatly in the meantime. Extensive studies of the electron screening effect in different nuclear reactions have shown always the same discrepancy, i.e. the experimental U_egg adiabatic U_e. In the recent years extensive studies of the elctron screening effect in deuterated metals (54 metals and 4 insulators) and other environments have been carried out in Bochum. Experimental results of anomalous enhancements have been interpreted in terms of the Debye plasma model, applied to quasi-free metallic electrons. Within this model, the deduced number of valence electrons per metallic atom also agrees with the corresponding number from the Hall coefficient. The expected temperature dependence of the screening potential has been verified together with the expected Zt scaling (with the metallic host) of the Debye radius.

Raiola, F.

252

Simulating the impacts of ionospheric scintillation on L band SAR image formation  

NASA Astrophysics Data System (ADS)

We develop a phase screen model called the Synthetic Aperture Radar (SAR) Scintillation Simulator (SAR-SS) for predicting the impacts of ionospheric scintillation on SAR image formation. SAR-SS consists of a phase screen generator and a propagator. The screen generator creates a 2-D random realization of spatial phase fluctuations resulting from the traversal of small-scale field-aligned irregularities in the ionosphere. It accounts for the motion of the radar platform, the drift of the ionospheric irregularities, and the oblique angle of propagation, all of which determine the scale sizes of the irregularities sampled by the radar beam. The propagator solves the 3-D parabolic wave equation using the split step technique to compute the ionospheric transfer function for two-way propagation. This ionospheric transfer function is used to modulate the SAR signal due to terrestrial features in order to assess the ionospheric impact on SAR image formation in the small target approximation. We compare simulated and observed PALSAR imagery over Brazil during disturbed ionospheric conditions. We demonstrate that SAR-SS can reproduce the field-aligned streaks in PALSAR imagery caused by irregularities in the equatorial ionosphere that have been observed by previous authors. The field-aligned streaks exhibited a dominant wavelength larger than the Fresnel break scale, which suggests that refractive scatter was dominant over diffraction as the physical mechanism responsible for the scintillation of the radar signal in this case. The spectral index of phase fluctuations in the screen was quite large (9.0), suggesting that these irregularities were possibly associated with bottomside sinudoidal irregularities rather than equatorial plasma bubbles.

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

2012-01-01

253

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

254

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

SciTech Connect

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

Lacroix, Frederic; Archambault, Louis; Gingras, Luc; Guillot, Mathieu; Beddar, A. Sam; Beaulieu, Luc [Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec, G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec, Quebec G1R2J6 (Canada); Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030 (United States); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec, Quebec G1R2J6 (Canada); Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030 (United States); Departement de Physique, de Genie Physique et d'Optique, Universite Laval, Quebec, Quebec, G1K 7P4 (Canada) and Departement de Radio-Oncologie, Hotel-Dieu de Quebec, Centre Hospitalier Universitaire de Quebec, Quebec, Quebec G1R2J6 (Canada)

2008-08-15

255

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

256

Primary and secondary scintillation measurements in a xenon Gas Proportional Scintillation Counter  

E-print Network

NEXT is a new experiment to search for neutrinoless double beta decay using a 100 kg radio-pure high-pressure gaseous xenon TPC. The detector requires excellent energy resolution, which can be achieved in a Xe TPC with electroluminescence readout. Hamamatsu R8520-06SEL photomultipliers are good candidates for the scintillation readout. The performance of this photomultiplier, used as VUV photosensor in a gas proportional scintillation counter, was investigated. Initial results for the detection of primary and secondary scintillation produced as a result of the interaction of 5.9 keV X-rays in gaseous xenon, at room temperature and at pressures up to 3 bar, are presented. An energy resolution of 8.0% was obtained for secondary scintillation produced by 5.9 keV X-rays. No significant variation of the primary scintillation was observed for different pressures (1, 2 and 3 bar) and for electric fields up to 0.8 V cm-1 torr-1 in the drift region, demonstrating negligible recombination luminescence. A primary scintillation yield of 81 \\pm 7 photons was obtained for 5.9 keV X-rays, corresponding to a mean energy of 72 \\pm 6 eV to produce a primary scintillation photon in xenon.

L. M. P. Fernandes; E. D. C. Freitas; M. Ball; J. J. Gómez-Cadenas; C. M. B. Monteiro; N. Yahlali; D. Nygren; J. M. F. dos Santos

2010-09-15

257

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

258

Photovoltaic nanocrystal scintillators hybridized on Si solar cells  

E-print Network

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

Demir, Hilmi Volkan

259

Interstellar scattering of pulsar radiation. I - Scintillation  

NASA Technical Reports Server (NTRS)

An investigation of the intensity fluctuations of 28 pulsars near 0.4 GHz indicates that spectra of interstellar scintillation are consistent with a Gaussian shape, that scintillation indices are near unity, and that the scintillation bandwidth depends linearly on dispersion measure. Observations at cm wavelengths show that the observer is in the near field of the scattering medium for objects with the lowest dispersion measures, and confirm the steep dependence of correlation bandwidth on dispersion measure found by Sutton (1971). The variations of scattering parameters with dispersion measure may indicate that the rms deviation of thermal electron density on the scale of 10 to the 11th cm grows with path length through the galaxy.

Backer, D. C.

1975-01-01

260

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

261

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

262

Get Screened  

MedlinePLUS

... Also, many screening tests are covered under the Affordable Care Act , the health care reform law passed in 2010. Depending on ... Find out which services are covered by the Affordable Care Act . Find out which ... health center near you to learn more . Pages: 1 ...

263

Screen Animals  

E-print Network

Screen animals – Introduction Laura McMahon From the protocinematic sequencing of Eadweard Muybridge’s horse and Etienne-Jules Marey’s cat to the proliferation of animal images on video-sharing platforms such as YouTube, the ontologies...

McMahon, Laura

2014-01-01

264

Sonoluminescence and high-pressure gas scintillators  

SciTech Connect

We point out striking similarities between the light emitted in single-bubble sonoluminescence and high-pressure gas scintillators. This observation can account for important and largely unexplained phenomena surrounding sonoluminescence. Especially, it explains the observed dramatic effects of the noble gas content on the spectral density of the light emitted from a sonoluminescence bubble in water. Based on studies with high-pressure gas scintillators, we also propose an alternative explanation for the extreme temperature sensitivity of sonoluminescence. {copyright} {ital 1996 The American Physical Society.}

Tornow, W. [Department of Physics, Duke University, Durham, North Carolina 27708 (United States)] [Department of Physics, Duke University, Durham, North Carolina 27708 (United States); [Triangle Universities Nuclear Laboratory, Duke Station, Durham, North Carolina 27708 (United States)

1996-05-01

265

Statistics of time averaged atmospheric scintillation  

SciTech Connect

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

Stroud, P.

1994-02-01

266

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

NASA Astrophysics Data System (ADS)

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

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

1999-05-01

267

Scintillations of cos-Gaussian and annular beams  

Microsoft Academic Search

Based on the generalized beam formulation, we derive the scintillation index and selectively evaluate it for cos-Gaussian and annular beams propagating in weak atmospheric turbulence. Dependence of the scintillation index on propagation length, focusing and displacement parameters, wavelength of operation, and source size are individually investigated. From our graphical outputs, it is observed that a cos-Gaussian beam exhibits lower scintillations

Halil T. Eyyuboglu; Yahya Baykal

2007-01-01

268

Novel radiation hard microfabricated scintillation detectors with high spatial resolution  

E-print Network

Novel radiation hard microfabricated scintillation detectors with high spatial resolution A, Switzerland a r t i c l e i n f o Available online 4 July 2009 Keywords: Scintillation detectors Microfabrication Microfluidics a b s t r a c t A novel liquid scintillation detector with high spatial resolution

Dalang, Robert C.

269

THE POSSIBILITY OF USING CERTAIN ORGANIC SCINTILLATORS FOR DOSIMETRY  

Microsoft Academic Search

The scintillators investigated are sindilar in composition to biological ; tissue. The dependence of the fast neutron absorption dose rate on neutron ; energy for these scintillators is similar to Snyder's curve for biological tissue. ; The results of investigations show that both the plastic and liquid scintillators ; can be used for fast neutron dosimetry. The dependence of the

Yu. A. Egorov; V. A. Kucheryaev

1961-01-01

270

Comparative Study of Plastic Scintillators for Dosimetric Applications  

Microsoft Academic Search

Plastic scintillators are widely studied for radiotherapy dosimetry because of their very interesting properties and especially their water equivalence. Nevertheless, to ensure accurate dose measurements, the properties of the scintillators must be very well known and adapted to this application. We studied six plastic scintillators manufactured by two different companies (Bicron and Amcrys-H) in terms of emission spectrum, light yield,

Anne-Marie Frelin; Jean-Marc Fontbonne; Gilles Ban; Jean Colin; Marc Labalme

2008-01-01

271

Design of tissue equivalent scintillators for precise dosimetry purposes  

Microsoft Academic Search

A tissue equivalent plastic scintillator containing Chlorine has been designed through Monte Carlo simulations and mass energy transfer coefficient calculations, searching for the optimum concentration of that element whose role is to make the value of the absorbed radiation energy equal in tissue and plastic scintillators. The plastic is obtained by mixing the base component of most current plastic scintillators,

Raúl T. Mainardi; Edgardo V. Bonzi; Victor Delgado Martinez

1997-01-01

272

Upconverting nanoparticles for optimizing scintillator based detection systems  

DOEpatents

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

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

2013-09-17

273

Robust GPS carrier tracking under ionospheric scintillation  

NASA Astrophysics Data System (ADS)

Small scale irregularities present in the ionosphere can induce fast and unpredictable fluctuations of Radio Frequency (RF) signal phase and amplitude. This phenomenon, known as scintillation, can degrade the performance of a GPS receiver leading to cycle slips, increasing the tracking error and also producing a complete loss of lock. In the most severe scenarios, if the tracking of multiple satellites links is prevented, outages in the GPS service can also occur. In order to render a GPS receiver more robust under scintillation, particular attention should be dedicated to the design of the carrier tracking stage, that is the receiver's part most sensitive to these types of phenomenon. This paper exploits the reconfigurability and flexibility of a GPS software receiver to develop a tracking algorithm that is more robust under ionospheric scintillation. For this purpose, first of all, the scintillation level is monitored in real time. Indeed the carrier phase and the post correlation terms obtained by the PLL (Phase Locked Loop) are used to estimate phi60 and S4 [1], the scintillation indices traditionally used to quantify the level of phase and amplitude scintillations, as well as p and T, the spectral parameters of the fluctuations PSD. The effectiveness of the scintillation parameter computation is confirmed by comparing the values obtained by the software receiver and the ones provided by a commercial scintillation monitoring, i.e. the Septentrio PolarxS receiver [2]. Then the above scintillation parameters and the signal carrier to noise density are exploited to tune the carrier tracking algorithm. In case of very weak signals the FLL (Frequency Locked Loop) scheme is selected in order to maintain the signal lock. Otherwise an adaptive bandwidth Phase Locked Loop (PLL) scheme is adopted. The optimum bandwidth for the specific scintillation scenario is evaluated in real time by exploiting the Conker formula [1] for the tracking jitter estimation. The performance of the proposed tracking scheme is assessed by using both simulated and real data. Real data have been collected in Vietnam by using a USRP (Universal Software Radio Peripheral) N210 front end connected to a rubidium oscillator. Selected events are exploited in order to challenge the algorithm with strong phase and amplitude variations. Moreover, simulated data have been collected by using the prototype of a digital front end developed by Novatel, namely the 'Firehose'. Since the latter includes a TCXO oscillator, the proposed tracking scheme is also opportunely modified to take in account the clock error contribution. References 1. R.S., Conker, M. B. El-Arini, C. J. Hegarty, and T. Hsiao, Modelling the effects of ionospheric scintillation on GPS/satellite-based augmentation system availability. Radio Sci., 38, 1, 1001, doi: 10.1029/2000RS002604, 2003. 2. B. Bougard et al, 'CIGALA: Challenging the Solar Maximum in Brazil with PolaRxS,' ION GNSS, Portland, Sept. 2011.

Susi, M.; Andreotti, M.; Aquino, M. H.; Dodson, A.

2013-12-01

274

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

275

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

276

A high throughput scintillation proximity imaging assay for protein methyltransferases.  

PubMed

Protein methyltransferases (PMTs) orchestrate epigenetic modifications through post-translational methylation of various protein substrates including histones. Since dysregulation of this process is widely implicated in many cancers, it is of pertinent interest to screen inhibitors of PMTs, as they offer novel target-based opportunities to discover small molecules with potential chemotherapeutic use. We have thus developed an enzymatic screening strategy, which can be adapted to scintillation proximity imaging assay (SPIA) format, to identify these inhibitors. We took advantage of S-adenosyl-L-[3H-methyl]-methionine availability and monitored the enzymatically catalyzed [3H]-methyl addition on lysine residues of biotinylated peptide substrates. The radiolabeled peptides were subsequently captured by streptavidin coated SPA imaging PS beads. We applied this strategy to four PMTs: SET7/9, SET8, SETD2, and EuHMTase1, and optimized assay conditions to achieve Z' values ranging from 0.48 to 0.91. The robust performance of this SPIA for the four PMTs was validated in a pilot screen of approximately 7,000 compounds. We identified 80 cumulative hits across the four targets. NF279, a suramin analogue, was found to specifically inhibit SET7/9 and SETD2 with IC50 values of 1.9 and 1.1 ?M, respectively. Another identified compound, Merbromin, a topical antiseptic, was classified as a pan-active inhibitor of the four PMTs. These findings demonstrate that our proposed SPIA strategy is generic for multiple PMTs and can be successfully implemented to identify novel and specific inhibitors of PMTs. The specific PMT inhibitors may constitute a new class of anti-proliferative agents for potential therapeutic use. PMID:22256970

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

2012-06-01

277

A High Throughput Scintillation Proximity Imaging Assay for Protein Methyltransferases  

PubMed Central

Protein methyltransferases (PMTs) orchestrate epigenetic modifications through post-translational methylation of various protein substrates including histones. Since dysregulation of this process is widely implicated in many cancers, it is of pertinent interest to screen inhibitors of PMTs, as they offer novel target-based opportunities to discover small molecules with potential chemotherapeutic use. We have thus developed an enzymatic screening strategy, which can be adapted to scintillation proximity imaging assay (SPIA) format, to identify these inhibitors. We took advantage of S-adenosyl-L-[3H-methyl]-methionine availability and monitored the enzymatically catalyzed [3H]-methyl addition on lysine residues of biotinylated peptide substrates. The radiolabeled peptides were subsequently captured by streptavidin coated SPA imaging PS beads. We applied this strategy to four PMTs: SET7/9, SET8, SETD2, and EuHMTase1, and optimized assay conditions to achieve Z? values ranging from 0.48 to 0.91. The robust performance of this SPIA for the four PMTs was validated in a pilot screen of approximately 7,000 compounds. We identified 80 cumulative hits across the four targets. NF279, a suramin analogue found to specifically inhibit SET7/9 and SETD2 with IC50 values of 1.9 and 1.1 ?M, respectively. Another identified compound, Merbromin, a topical antiseptic, was classified as a pan-active inhibitor of the four PMTs. These findings demonstrate that our proposed SPIA strategy is generic for multiple PMTs and can be successfully implemented to identify novel and specific inhibitors of PMTs. The specific PMT inhibitors may constitute a new class of anti-proliferative agents for potential therapeutic use. PMID:22256970

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

2013-01-01

278

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

Microsoft Academic Search

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

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

2006-01-01

279

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

Microsoft Academic Search

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

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

2010-01-01

280

Newborn Screening  

NSDL National Science Digital Library

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

American Association for the Advancement of Science (; )

2005-03-07

281

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

282

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

Microsoft Academic Search

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

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

283

High resolution scintillation detector with semiconductor readout  

DOEpatents

A novel high resolution scintillation detector array for use in radiation imaging such as high resolution Positron Emission Tomography (PET) which comprises one or more parallelepiped crystals with at least one long surface of each crystal being in intimate contact with a semiconductor photodetector such that photons generated within each crystal by gamma radiation passing therethrough is detected by the photodetector paired therewith.

Levin, Craig S. (Santa Monica, CA); Hoffman, Edward J. (Los Angeles, CA)

2000-01-01

284

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

285

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

286

Waveshifting fiber readout of lanthanum halide scintillators  

NASA Astrophysics Data System (ADS)

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

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

2006-07-01

287

Fluorescent compounds for plastic scintillation applications  

SciTech Connect

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

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

1994-04-01

288

Imaging of gamma emitters using scintillation cameras  

Microsoft Academic Search

Since their introduction by Hal Anger in the late 1950s, the gamma cameras have been widely used in the field of nuclear medicine. The original concept is based on the association of a large field of view scintillator optically coupled with an array of photomultiplier tubes (PMTs), in order to locate the position of interactions inside the crystal. Using a

Marcel Ricard

2004-01-01

289

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

290

Plastic scintillator dosimetry in radiology applications  

Microsoft Academic Search

Plastics have attractive characteristics that can be exploit in dosimetry. Nevertheless their application with low-energy photon beam is still limited. We aim to a better understanding of their capabilities at the radiology regime. A study of the characteristics of a polystyrene scintillator dosimeter, coupled to a WLS fiber is made in this work. The energy dependence for this detector is

Carmen H. Oliveira; Florbela Rego; Luis Peralta; Maria C. Abreu

2011-01-01

291

Low background liquid scintillation analyzer circuit design  

Microsoft Academic Search

Liquid scintillation technique was developed from the early fifties as an effective way to measure the low energy radiation. It can detect more than half of the periodic table of elements. And it is widely used in industry, agriculture, biology, chemistry, medicine, geology, hydrology, archeology, environmental protection and other fields. When measuring on low energy p-ray and low penetration a-ray

Guangxiang Wang; Liangxun Shuo; Juguang Li

2011-01-01

292

Modeling and scientific application of scintillation results  

Microsoft Academic Search

Efforts continue to update and improve empirical models of the mean morphological behavior of ionospherically produced scintillation. While often intended for engineering application, these models also can be scientifically useful to the extent that they describe not only the signal fluctuations but also the plasma density irregularities that cause them. Such a model is contained in the computer code called

E. J. Frernouw; J. A. Secan

1984-01-01

293

An improved model of equatorial scintillation  

Microsoft Academic Search

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

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

1995-01-01

294

An improved model of equatorial scintillation  

NASA Astrophysics Data System (ADS)

One of the main limitations of the modeling work that went into the equatorial section of the Wideband ionospheric scintillation model (WBMOD) was that the data set used in the modeling was limited to two stations near the dip equator (Ancon, Peru, and Kwajalein Island, in the North Pacific Ocean) at two fixed local times (nominally 1000 and 2200). Over the past year this section of the WBMOD model has been replaced by a model developed using data from three additional stations (Ascension Island, in the South Atlantic Ocean, Huancayo, Peru, and Manila, Phillipines; data collected under the auspices of the USAF Phillips Laboratory Geophysics Directorate) which provide a greater diversity in both latitude and longitude, as well as cover the entire day. The new model includes variations with latitude, local time, longitude, season, solar epoch, and geomagnetic activity levels. The way in which the irregularity strength parameter CkL is modeled has also been changed. The new model provides the variation of the full probability distribution function (PDF) of log (CkL) rather than simply the average of log (CkL). This permits the user to specify a threshold on scintillation level, and the model will calculate the percent of the time that scintillation will exceed that level in the user-specified scenario. It will also permit calculation of scintillation levels at a user-specified percentile. A final improvement to the WBMOD model is the implementation of a new theory for calculating S4 on a two-way channel.

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

1995-05-01

295

Modeling and scientific application of scintillation results  

Microsoft Academic Search

At many locations around the world, observations have been made of ionospherically imposed radio wave scintillations. There is, therefore, a need for an orderly means to assemble the data. Computer-based models intended for application to transionospheric communication systems provide such a scientifically useful repository of information. The present study is concerned with an attempt to illustrate such models with the

E. J. Fremouw; J. A. Secan

1984-01-01

296

Quadruple screen test  

MedlinePLUS

... screen; Multiple marker screening; AFP plus; Triple screen test; AFP maternal; MSAFP; 4-marker screen ... This test is most often done between the 15th and 22nd weeks of the pregnancy. It is most accurate ...

297

Liquid scintillator production for the NOvA experiment  

E-print Network

The NOvA collaboration blended and delivered 8.8 kt (2.72M gal) of liquid scintillator to its detectors as its active detector medium. The composition of the scintillator was developed to meet the requirements of the experiment. The scintillator was shipped to the NOvA near and far detectors using dedicated stainless steel tanker trailers. A rigorous set of quality control procedures were put in place to assure that the liquid scintillator was blended to satisfy the transparency, light yield, and conductivity requirements. The incoming components, the blended scintillator, and the scintillator in the transport tanker trailers were all qualified with these procedures, which ensured that the NOvA scintillator was high quality and met its performance requirements.

S. Mufson; B. Baugh; C. Bower; T. Coan; J. Cooper; L. Corwin; J. Karty; P. Mason; A. Pla-Dalmau; M. Proudfoot

2015-04-15

298

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

299

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

300

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

301

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

302

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

303

Screening for EGFR mutations in lung cancer.  

PubMed

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

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

2009-12-01

304

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.

Children's Museum of Houston

2011-01-01

305

Ionospheric scintillation monitoring and mitigation using a software GPS receiver  

NASA Astrophysics Data System (ADS)

Scintillations are caused by ionospheric irregularities and affect the amplitude, phase, dispersion, and related parameters of GPS signals. Both L1 and L2 are affected in a somewhat uncorrelated fashion. Adequate understanding of the effects that ionospheric scintillation has on GPS signals is essential in order to produce a GPS receiver that is immune to the degradation of signal caused by these scintillation-related effects. Access to the internal workings of commercial GPS receivers is not provided to users. However, in order to understand, control, and mitigate scintillation effects, it is necessary to have access to tracking loops and associated components such as local oscillator. The software GPS receiver developed by the Center for Remote Sensing, Inc. allows the user to access its internal workings; hence facilitating advanced development of GPS receivers under different conditions. In this paper we present the results of analysis of GPS signals under scintillating conditions. Raw signals under conditions of ionospheric scintillation at Ascension Island have been processed using our software GPS receiver in order to derive the scintillation parameters. The receiver has been configured to provide stable operation during scintillation. We describe the receiver architecture, particularly the portion involving the tracking filters and related components, and demonstrate their performances under scintillating conditions. The software-based approach used by us allows receiver implementations which are suitable for ionospheric monitoring as well as for reliable operation during scintillating conditions. The improved architecture may be used for several other applications.

Ganguly, Suman; Jovancevic, Aleksandar; Brown, Andrew; Kirchner, Michael; Zigic, Slavisa; Beach, Theodore; Groves, Keith M.

2004-02-01

306

Monitoring and Forecasting Ionospheric Scintillation at High Latitudes (Invited)  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

307

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

308

PAC studies with LSO scintillation crystals  

NASA Astrophysics Data System (ADS)

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

Valentini, Riccardo; Vianden, Reiner

2010-11-01

309

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

310

Reflectance of polytetrafluoroethylene for xenon scintillation light  

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

311

Codoped direct-gap semiconductor scintillators  

DOEpatents

Fast, bright inorganic scintillators at room temperature are based on radiative electron-hole recombination in direct-gap semiconductors, e.g. CdS and ZnO. The direct-gap semiconductor is codoped with two different impurity atoms to convert the semiconductor to a fast, high luminosity scintillator. The codopant scheme is based on dopant band to dopant trap recombination. One dopant provides a significant concentration of carriers of one type (electrons or holes) and the other dopant traps carriers of the other type. Examples include CdS:In,Te; CdS:In,Ag; CdS:In,Na; ZnO:Ga,P; ZnO:Ga,N; ZnO:Ga,S; and GaN:Ge,Mg.

Derenzo, Stephen E.; Bourret-Courchesne, Edith; Weber, Marvin J.; Klintenberg, Mattias K.

2006-05-23

312

Scintillating 99Tc Selective Ion Exchange Resins  

SciTech Connect

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

Mitchell Greenhalgh; Richard D. Tillotson

2012-07-01

313

Development of High-Resolution Scintillator Systems  

SciTech Connect

Mercuric iodide (HgI2) is a well known material for the direct detection of gamma-rays; however, the largest volume achievable is limited by the thickness of the detector which needs to be a small fraction of the average trapping length for electrons. We report results of using HgI2 crystals to fabricate photocells used in the readout of scintillators. The optical spectral response and efficiency of these photocells were measured and will be reported. Nuclear response from an HgI2 photocell that was optically matched to a cerium-activated scintillator is presented and discussed. Further improvements can be expected by optimizing the transparent contact technology.

Larry A. Franks; Warnick J. Kernan

2007-09-01

314

Hard X-ray polarimetry using scintillators.  

NASA Astrophysics Data System (ADS)

The linear polarization of the radiation from celestial sources can be investigated by studying the angular distribution of Compton scattered photons in a detection device. The authors present the design of a Compton polarimeter based on the technology of fiber-shaped scintillators. A total geometric area of 1000 cm2 or more could be obtained by repeating a basic polarimeter composed by several fiber-like scintillators, some of them of low Z, acting as active scatterers, and others of high Z, acting as detectors. Polarimetric measurements can thus be carried out by searching for coincidences between a scatterer fiber and an absorber one. Monte Carlo simulations of the performances of such a device, when employed onboard a stratospheric balloon, are compared with other kinds of X-ray polarimeters.

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

1997-10-01

315

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

316

Plastic fiber scintillator response to fast neutrons  

SciTech Connect

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. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

2014-11-15

317

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

SciTech Connect

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

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

2006-01-15

318

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

PubMed

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

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

2014-04-21

319

A scintillation counter for nuclear research  

E-print Network

. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 23 10 Integral Curve for Thorium. . . . . . . . . . . . . ~ ~ . . ~ . . ~. . . . ~ . 27 ll Differential Curve for Thorium. 12 Integral Curves fox' Radium. . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 3C 13 Diffsxential Cux'ves fer Radium...'fer Power Supply Pulse-Height Selector and Scalar CALIBRATING THE SPECTROMETER TH QH IUN RADIUM GAL I ENATION CONCLUSION BIBLIOGRAPHY 19 19 19 22 D 22 25 25 29 32 34 36 AB~THAGT A scintillation spectrometer using a napht? alene crystal...

Trail, Carroll Clark

1951-01-01

320

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

321

Lutetium aluminate: spectroscopic and scintillation properties  

Microsoft Academic Search

The present status of the LuAlO3:Ce (LuAP) scintillator is reviewed and its performance compared to that of YAlO3:Ce (YAP). The light output of LuAP, at this stage of development, appears to be limited by two factors: insufficient Ce concentration and the presence of a parasitic absorption, Both LuAP and YAP show a dependence of light output on thickness, indicating that

A. Lempicki; C. Brecher; D. Wisniewski; E. Zych; A. J. Wojtowicz

1996-01-01

322

LIQUID SCINTILLATION COUNTING OF NICKEL63  

Microsoft Academic Search

Liquid scintillation systems based on gels, ether, and toluene are ; investigated for counting nickel-63. A nickel complex of n-caproic acid ; dissolved in a solution of toluene containing 1,4-bis(2-(5-phenloxazolyl)-; benzene(POPOP) and 2,5-diphenyloxazole (PPO) is found to be prefterable with ; respect to reproducibility, ease of preparation, and interpretation. The ; addition of a small quantity of ethyl alcohol produces

C. E. Gleit; J. Dumot

1961-01-01

323

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

324

Current trends in scintillator detectors and materials  

Microsoft Academic Search

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

Moses; William W

2001-01-01

325

Current trends in scintillator detectors and materials  

Microsoft Academic Search

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

William W. Moses

2002-01-01

326

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

327

Semiconductor high-energy radiation scintillation detector  

Microsoft Academic Search

We propose a new scintillation-type detector in which high-energy radiation generates electron–hole pairs in a direct-gap semiconductor material that subsequently recombine producing infrared light to be registered by a photo-detector. The key issue is how to make the semiconductor essentially transparent to its own infrared light, so that photons generated deep inside the semiconductor could reach its surface without tangible

A. Kastalsky; S. Luryi; B. Spivak

2006-01-01

328

Studies of NICADD Extruded Scintillator Strips  

SciTech Connect

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

Dychkant, Alexandre; et al.

2005-03-01

329

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

330

Newborn Screening  

PubMed Central

Early detection of many disorders, mainly inherited, is feasible with population-wide analysis of newborn dried blood spot samples. Phenylketonuria was the prototype disorder for newborn screening (NBS) and early dietary treatment has resulted in vastly improved outcomes for this disorder. Testing for primary hypothyroidism and cystic fibrosis (CF) was later added to NBS programs following the development of robust immunoassays and molecular testing. Current CF testing usually relies on a combined immunoreactive trypsin/mutation detection strategy. Multiplex testing for approximately 25 inborn errors of metabolism using tandem mass spectrometry is a relatively recent addition to NBS. The simultaneous introduction of many disorders has caused some re-evaluation of the traditional guidelines for NBS, because very rare disorders or disorders without good treatments can be included with minimal effort. NBS tests for many other disorders have been developed, but these are less uniformly applied or are currently considered developmental. This review focuses on Australasian NBS practices. PMID:20498829

Pitt, James J

2010-01-01

331

Boron-Loaded Silicone Rubber Scintillators  

SciTech Connect

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

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

2003-05-12

332

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

333

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

334

Scintillation theory of eclipse shadow bands  

SciTech Connect

The results of a theoretical investigation of solar eclipse shadow bands are presented. The study provides both quantitative and qualitative insight into the factors governing the visibility of shadow bands. Using only standard, weak-scattering scintillation theory and standard models for atmospheric turbulence, all of the salient features of the shadow bands are explained. The contrast is found to be greater for shorter wavelengths and the band spacing to scale like the square-root of the wavelength very near totality. For times greater than about 20 seconds before (or after) totality the band spacing becomes frequency-independent and the scintillations are dominated by turbulence near the ground. The turbulence mainly responsible for shadow bands is found to be below two kilometers in altitude. Turbulence at the tropopause is found to have no impact on shadow bands until 2-3 seconds from totality. Longer eclipes are expected to show bands with greater contrast and linearity. Intensity correlation scales are typically less than 10cm within 30 seconds of totality. The scintillation theory predictions for shadow band structure motion, and evolution are found to be in agreement with both visual and photoelectric observations.

Codona, J.L.

1986-01-01

335

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

NASA Astrophysics Data System (ADS)

Ionospheric scintillation at low latitudes has been studied using ionospheric radio occultation (RO) measurements by the FORMOSAT-3/COSMIC micro-satellites in conjunction with ground-based data from the Scintillation Network Decision Aid (SCINDA) station at Kwajalein Atoll. The Air Force Research Laboratory has developed the SCINDA network for monitoring low-latitude ionospheric total electron content (TEC) and scintillation associated with equatorial spread F. The network currently consists of sixteen stations distributed around the globe and the data have been used to conduct numerous studies on the characteristics and climatology of equatorial scintillation. The present study focuses on COSMIC RO and SCINDA data during the three COSMIC campaigns in 2006. Radio occultation events are selected by requiring that ionospheric scintillation was detected by the SCINDA VHF scintillation monitor at Kwajalein, and that the occultation ray path intersected the Kwajalein longitude below the satellite altitude, which varied from 500 to 800 km for the six FORMOSAT-3 satellites. In order to exclude tropospheric effects, only GPS signal amplitudes from FORMOSAT-3 with ray path tangent altitudes above 100 km are considered. Locations of ionospheric scintillation are estimated by triangulation using the satellites and the SCINDA ground station. Airglow images at Kwajalein are also used to confirm occurrence of equatorial ionospheric scintillations. For the selected events, large amplitude L1 and L2 scintillations tend to occur at altitudes below 200 km at frequencies around 0.5 Hz. The results are discussed as a potential path toward better specifying the occurrence of equatorial scintillations.

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

2007-05-01

336

Residence Guide 1760 Residence Guide  

E-print Network

Pets Pool Table Rooftops Restricted Areas Security Signage Smoking Solicitation Sports Storage Threats and Violence Vandalism Windows GENERAL SAFETY INFORMATION #12;1760 Residence Guide 3 STUDENTS' RIGHTS

Qiu, Weigang

337

Product Guide  

Microsoft Academic Search

This guide identifies manufacturers and suppliers serving the fields of air and waste management. It enables the reader to select a firm based on the products supplied and geographical proximity. To use this guide: 1. Identify the product you need from the following lists.2. Identify the firms that provide that product in the “List of Companies by Product3. Check the

1994-01-01

338

Phase and coherence analysis of VHF scintillation over Christmas Island  

NASA Astrophysics Data System (ADS)

This short paper presents phase and coherence data from the cross-wavelet transform applied on longitudinally separated very high frequency (VHF) equatorial ionospheric scintillation observations over Christmas Island. The phase and coherence analyses were employed on a pair of scintillation observations, namely, the east-looking and west-looking VHF scintillation monitors at Christmas Island. Our analysis includes 3 years of peak season scintillation data from 2008, 2009 (low solar activity), and 2011 (moderate solar activity). In statistically significant and high spectral coherence regions of the cross-wavelet transform, scintillation observations from the east-looking monitor lead those from the west-looking monitor by about 20 to 60 (40 ± 20) min (most frequent lead times). Using several years (seasons and solar cycle) of lead (or lag) and coherence information of the cross-wavelet transform, we envisage construction of a probability model for forecasting scintillation in the nighttime equatorial ionosphere.

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

2014-03-01

339

New scintillator: cerium-doped dense oxide glass  

NASA Astrophysics Data System (ADS)

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

Jiang, Chun; Zeng, Qingji; Gan, Fuxi

2000-10-01

340

Methods for the continuous production of plastic scintillator materials  

DOEpatents

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

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

1999-10-19

341

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

342

Optical scintillation measurements in a desert environment IV: simulated effects of scintillation on communications links  

NASA Astrophysics Data System (ADS)

Optical scintillation is an effect that limits the performance of many optical systems including imagers and free space optical communication links. The Naval Research Laboratory is undertaking a series of measurement campaigns of optical scintillation in a variety of environments. In December of 2010 measurements were made over a one week period in the desert at China Lake, CA. The NRL TATS system was used to measure time resolved scintillation over a variety of different ranges and terrains. This data has been used to determine fade rate and duration as a function of weather and link margin. Temporal correlation of fades has also been calculated. This data allows simulation of a variety of communication protocols and the effects of those protocols on link throughput. In this paper we present a comparison of different protocols for both direct and retroreflector links.

Suite, Michele; Rabinovich, W. S.; Mahon, Rita; Moore, Christopher; Ferraro, Mike; Burris, H. R., Jr.; Thomas, L. M.

2011-09-01

343

Rational screening strategies.  

PubMed

Screening for disease can significantly improve both individual and public health. Many different screening interventions have been proposed for a wide range of conditions. This article reviews the elements that make up an effective clinical screening test and discusses what it means to effectively detect and treat a condition, risks and benefits of screening and the measurement of outcomes from screening. PMID:21117518

Huntington, Mark K; Thanel, Fredric H

2010-11-01

344

Systematic studies of small scintillators for new sampling calorimeter  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

345

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

346

Plastic scintillator investigations for relative dosimetry in proton-therapy  

Microsoft Academic Search

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

L. Torrisi

2000-01-01

347

The Scintillator Purification System for the Borexino Solar Neutrino Detector  

E-print Network

Purification of the 278 tons of liquid scintillator and 889 tons of buffer shielding for the Borexino solar neutrino detector was performed with a system that combined distillation, water extraction, gas stripping and filtration. The purification of the scintillator achieved unprecedented low backgrounds for the large scale liquid scintillation detector. This paper describes the principles of operation, design, construction and commissioning of the purification system, and reviews the requirements and methods to achieve system cleanliness and leak-tightness.

Benziger, J; Cadonati, L; Calaprice, F; Chen, M; Corsi, A; Cubaiu, A; Dalnoki-Veress, F; Di Pietro, G; Fernholz, R; Ford, R; Galbiati, C; Gazzana, S; Goretti, A; Harding, E; Ianni, Aldo; Ianni, Andrea; Kidner, S; Korga, G; Leung, M; Löser, F; Lombardi, P; McCarty, K; McKinsey, D; Montanari, D; Nelson, A; Orsini, M; Papp, L; Parmeggiano, S; Pocar, A; Salvo, C; Schimizzi, D; Shutt, T; Sonnenschein, A; Soricelli, F; Suvorov, Y

2007-01-01

348

Properties of the high-density scintillator cerium fluoride  

Microsoft Academic Search

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

D. F. Anderson

1989-01-01

349

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

350

Composite solid-state scintillators for neutron detection  

DOEpatents

Applicant's present invention is a composite scintillator for neutron detection comprising a matrix material fabricated from an inorganic sol-gel precursor solution homogeneously doped with a liquid scintillating material and a neutron absorbing material. The neutron absorbing material yields at least one of an electron, a proton, a triton, an alpha particle or a fission fragment when the neutron absorbing material absorbs a neutron. The composite scintillator further comprises a liquid scintillating material in a self-assembled micelle formation homogeneously doped in the matrix material through the formation of surfactant-silica composites. The scintillating material is provided to scintillate when traversed by at least one of an electron, a proton, a triton, an alpha particle or a fission fragment. The scintillating material is configured such that the matrix material surrounds the micelle formation of the scintillating material. The composite scintillator is fabricated and applied as a thin film on substrate surfaces, a coating on optical fibers or as a glass material.

Dai, Sheng; Im, Hee-Jung; Pawel, Michelle D.

2006-09-12

351

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

352

GPS proxy model for real-time UHF satellite communications scintillation maps from the Scintillation Network Decision Aid (SCINDA)  

Microsoft Academic Search

In order to provide a more reliable situational awareness of scintillation impacts on users of space-based communication\\/navigation systems, L-band scintillation measurements from GPS satellites are ingested, in real time, to the Scintillation Network Decision Aid (SCINDA) model. SCINDA is a real-time, data-driven communication outage forecast and alert system developed by the Air Force Research Laboratory at Hanscom Air Force Base

R. G. Caton; W. J. McNeil; K. M. Groves; S. Basu

2004-01-01

353

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

Microsoft Academic Search

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

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

2007-01-01

354

Skin Cancer Screening  

MedlinePLUS

... Dictionary Search for Clinical Trials NCI Publications Español Skin Cancer Screening (PDQ®) Skin Cancer Screening Key Points for This Section Tests ... trials is available from the NCI Web site . Skin exams are used to screen for skin cancer. ...

355

Mental Health Screening Center  

MedlinePLUS

Mental Health Screening Center These online screening tools are not a substitute for consultation with a health professional. ... you have any concerns, see your doctor or mental health professional. Depression This screening form was developed from ...

356

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 ...

357

Lung Cancer Screening  

MedlinePLUS

Lung Cancer Screening Key Points for This Section Tests are used to screen for different types of cancer. ... if they decrease the risk of dying from lung cancer. The following screening tests have been studied to ...

358

Colorectal Cancer Screening  

MedlinePLUS

... colonoscopy DNA stool test Tests are used to screen for different types of cancer. Some screening tests ... from the disease. Four tests are used to screen for colorectal cancer: Fecal occult blood test A ...

359

Comparison of Luminescence ADP Production Assay and Radiometric Scintillation Proximity Assay for Cdc7 Kinase  

PubMed Central

Several assay technologies have been successfully adapted and used in HTS to screen for protein kinase inhibitors; however, emerging comparative analysis studies report very low hit overlap between the different technologies, which challenges the working assumption that hit identification is not dependent on the assay method of choice. To help address this issue, we performed two screens on the cancer target, Cdc7-Dbf4 heterodimeric protein kinase, using a direct assay detection method measuring [33P]-phosphate incorporation into the substrate and an indirect method measuring residual ADP production using luminescence. We conducted the two screens under similar conditions, where in one, we measured [33P]-phosphate incorporation using scintillation proximity assay (SPA), and in the other, we detected luminescence signal of the ATP-dependent luciferase after regenerating ATP from residual ADP (LUM). Surprisingly, little or no correlation were observed between the positives identified by the two methods; at a threshold of 30% inhibition, 25 positives were identified in the LUM screen whereas the SPA screen only identified two positives, Tannic acid and Gentian violet, with Tannic acid being common to both. We tested 20 out of the 25 positive compounds in secondary confirmatory study and confirmed 12 compounds including Tannic acid as Cdc7-Dbf4 kinase inhibitors. Gentian violet, which was only positive in the SPA screen, inhibited luminescence detection and categorized as a false positive. This report demonstrates the strong impact in detection format on the success of a screening campaign and the importance of carefully designed confirmatory assays to eliminate those compounds that target the detection part of the assay. PMID:21564015

Takagi, Toshimitsu; Shum, David; Parisi, Monika; Santos, Ruth E.; Radu, Constantin; Calder, Paul; Rizvi, Zahra; Frattini, Mark G.; Djaballah, Hakim

2013-01-01

360

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

361

Bipolar climatology of GPS ionospheric scintillation at solar minimum  

NASA Astrophysics Data System (ADS)

High-rate sampling data of Global Navigation Satellite Systems ionospheric scintillation acquired by a network of GPS Ionospheric Scintillation and TEC Monitor receivers located in the Svalbard Islands, in Norway and in Antarctica have been analyzed. The aim is to describe the “scintillation climatology” of the high-latitude ionosphere over both the poles under quiet conditions of the near-Earth environment. For climatology we mean to assess the general recurrent features of the ionospheric irregularities dynamics and temporal evolution on long data series, trying to catch eventual correspondences with scintillation occurrence. In spite of the fact that the sites are not geomagnetically conjugate, long series of data recorded by the same kind of receivers provide a rare opportunity to draw a picture of the ionospheric features characterizing the scintillation conditions over high latitudes. The method adopted is the Ground Based Scintillation Climatology, which produces maps of scintillation occurrence and of total electron content relative variation to investigate ionospheric scintillations scenario in terms of geomagnetic and geographic coordinates, interplanetary magnetic field conditions and seasonal variability. By means of such a novel and original description of the ionospheric irregularities, our work provides insights to speculate on the cause-effect mechanisms producing scintillations, suggesting the roles of the high-latitude ionospheric trough, of the auroral boundaries and of the polar cap ionosphere in hosting those irregularities causing scintillations over both the hemispheres at high latitude. The method can constitute a first step toward the development of new algorithms to forecast the scintillations during space weather events.

Alfonsi, Lucilla; Spogli, Luca; De Franceschi, Giorgiana; Romano, Vincenzo; Aquino, Marcio; Dodson, Alan; Mitchell, Cathryn N.

2011-06-01

362

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

Microsoft Academic Search

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

J. M. Retterer

2010-01-01

363

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

364

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].

365

Cherenkov and Scintillation Properties of Cubic Zirconium  

NASA Technical Reports Server (NTRS)

Cubic zirconium (CZ) is a high index of refraction (n =2.17) material that we have investigated for Cherenkov counter applications. Laboratory and proton accelerator tests of an 18cc sample of CZ show that the expected fast Cherenkov response is accompanied by a longer scintillation component that can be separated by pulse shaping. This presents the possibility of novel particle spectrometers which exploits both properties of CZ. Other high index materials being examined for Cherenkov applications will be discussed. Results from laboratory tests and an accelerator exposure will be presented and a potential application in solar energetic particle instruments will be discussed

Christl, M.J.; Adams, J.H.; Parnell, T.A.; Kuznetsov, E.N.

2008-01-01

366

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

367

Modeling and scientific application of scintillation results  

NASA Astrophysics Data System (ADS)

At many locations around the world, observations have been made of ionospherically imposed radio wave scintillations. There is, therefore, a need for an orderly means to assemble the data. Computer-based models intended for application to transionospheric communication systems provide such a scientifically useful repository of information. The present study is concerned with an attempt to illustrate such models with the aid of a particular model which was developed during a period of several years. This model resides now in a computer code called WBMOD. Attention is given to the elements of a scientifically useful model, the employed modelling approach, and the characteristics of the current model.

Fremouw, E. J.; Secan, J. A.

1984-06-01

368

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

369

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

370

Extremely long baseline interplanetary scintillation measurements of solar wind velocity  

Microsoft Academic Search

We present results of observations of interplanetary scintillation (IPS) made using the telescopes of the MERLIN and EISCAT networks in which the beam separation approached 2000 km, much larger than in any previous IPS experiments. Significant correlation between the scintillation patterns was observed at time lags of up to 8 s and fast and slow streams of solar wind were

A. R. Breen; R. A. Fallows; M. M. Bisi; P. Thomasson; C. A. Jordan; G. Wannberg; R. A. Jones

2006-01-01

371

WORK WITH A NOBLE GAS SCINTILLATION COUNTER (thesis)  

Microsoft Academic Search

Submitted to United States Naval Postgraduate School Monterey, Calif. ; More than 1450 runs were made and analyzed with a noble gas scintillation counter ; and its associated equip ment. The counter itself consists of a special ; photomultiplier tube looking into a scintillation chamber, and is used in ; conjunction with a vacuum and filling system, an output-pulse amplification

1958-01-01

372

Migraine aura and related phenomena: beyond scotomata and scintillations  

E-print Network

Migraine aura and related phenomena: beyond scotomata and scintillations MB Vincent1 & N Hadjikhani MB & Hadjikhani N. Migraine aura and related phenomena: beyond scotomata and scintillations. Cephalalgia 2007. London. ISSN 0333-1024 Migraine affects the cortical physiology and may induce dysfunction

Hadjikhani, Nouchine

373

A study of GPS ionospheric scintillations observed at Guilin  

NASA Astrophysics Data System (ADS)

The occurrence of strong ionospheric scintillations with S4>=0.2 was studied using global positioning system (GPS) measurements at Guilin (25.29°N, 110.33°E; geomagnetic: 15.04°N, 181.98°E), a station located near the northern crest of equatorial anomaly in China. The results are presented for data collected from January 2007 to December 2008. The results show that amplitude scintillations occurred only during the first five months of the considered years. Nighttime amplitude scintillations, observed mainly in the south of Guilin, always occurred with phase scintillations, total electron content (TEC) depletions, and Rate Of change of TEC (ROT) fluctuations. However, TEC depletions and ROT fluctuations were weak during daytime amplitude scintillations, and daytime amplitude scintillations usually occurred in most of the azimuth directions. GPS scintillation/TEC observations recorded at Guilin and signal-to-noise-ratio measurements obtained from GPS-COSMIC radio occultation indicate that nighttime and daytime scintillations are very likely caused by ionospheric F region irregularities and sporadic E, respectively.

Zou, Yuhua; Wang, Dongli

2009-12-01

374

Radiation imaging from multiple readout of a monolithic scintillator  

Microsoft Academic Search

A monolithic scintillator has advantages over segmented scintillators due to their reduced dead area and straightforward implementation. Previous methods have used a nearest neighbor approach to match multiple photodetector responses to entries in a predetermined look-up table (LUT). We extend this technique by introducing various inverse interpolation techniques, namely kriging, inverse distance weighting, and nonnegative least squares. These interpolation schemes

P. Barton; D. K. Wehe

2010-01-01

375

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

376

Miniature scintillating detector for small field radiation therapy D. Letourneaua)  

E-print Network

Miniature scintillating detector for small field radiation therapy D. Le´tourneaua) Centre curves, profiles, and dose rate of treatment beams are difficult to obtain with conventional detectors because of loss of lateral elec- tronic equilibrium and volume averaging. A scintillating detector

Pouliot, Jean

377

Performance comparison of scintillators for alpha particle detectors  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

378

Cerium doped silica scintillating fiber sensor for ? radiation measurement  

NASA Astrophysics Data System (ADS)

Remote optical fiber sensors for radiation measurement are very useful in high radiation fields. In this paper, we fabricated scintillating optical fiber by using a cerium-doped silica rod. In the drawing process, we obtained different fiber samples by changing the drawing temperature and speed. The drawing temperature is from 1900 to 2200 °C and the speed is from 1 to 10 m/min. The experimental results showed that the optical rod physical properties such as viscosity, tension and scintillating efficiency can be controlled by the parameters of temperature and speed. The optical properties and chemical composition of the scintillating optical fiber have been analyzed by Raman spectra and X-ray fluorescence spectrometer (XRF-1800, SHIMADZU). The concentration of the doped cerium is 0.55%. Moreover, a test system is proposed to measure the scintillating performance of the fabricated optical fibers. For the scintillating properties, the effect of fiber length, the number of fiber bundle and the detection angle were analyzed. Experimental results showed that the optimal length of the cerium doped fiber is ~15 cm. The scintillating light intensity increases linearly with the number of the fiber bundle. With two low intensity 60Co (0.2784 ?Ci) and 137Cs (1.0865 ?Ci) gamma radiation sources, the scintillating light can be detected the gamma sources by using the scintillating fiber sensor which is connected a MMF.

Guo, Qiang; Lin, Shiyang; Huang, Yi; Pang, Fufei; Chen, Zhenyi; Shang, Yana; Wang, Tingyun

2013-12-01

379

Statistical characteristics of low-latitude ionospheric scintillation over China  

NASA Astrophysics Data System (ADS)

The Global Positioning System (GPS) L-band ionospheric scintillation produced by electron density irregularities in the ionospheric E- and F-regions, is mainly a low- and high-latitude phenomenon. In this study, the statistical behavior of GPS ionospheric scintillation over a Chinese low-latitude station Sanya (18.3°N, 109.6°E; dip lat: 12.8°N) has been investigated. A detailed study on the seasonal and solar activity dependence of scintillation occurrence during July 2004-December 2012 show that the amplitude scintillation pattern, with a maximum occurrence during equinox of solar maximum, agrees with plasma bubble observations by in situ satellites in this longitude. A few daytime periodic scintillation events are found during June solstice months of solar minimum. Interestingly, a significant equinoctial asymmetry of scintillation onset time is found in 2011-2012. The initiation of scintillation during September-October is on average earlier than that of March-April about 25 min. Meanwhile, the zonal drifts of irregularities estimated using two spatially separated GPS receivers over Sanya show a similar behavior during the two equinoxes, slowly decreasing from 150 m/s at post-sunset to 50 m/s near midnight. The possible mechanisms responsible for the occurrence characteristics of GPS scintillation over Sanya, and relevant aspects of the zonal drifts of the irregularities are discussed.

Liu, Kangkang; Li, Guozhu; Ning, Baiqi; Hu, Lianhuan; Li, Hongke

2015-03-01

380

Surface preparation and coupling in plastic scintillator dosimetry  

Microsoft Academic Search

One way to improve the performance of scintillation dosimeters is to increase the light-collection efficiency at the coupling interfaces of the detector system. We performed a detailed study of surface preparation of scintillating fibers and their coupling with clear optical fibers to minimize light loss and increase the amount of light collected. We analyzed fiber-surface polishing with aluminum oxide sheets,

Guylaine Ayotte; Louis Archambault; Luc Gingras; Fre?de?ric Lacroix; A. Sam Beddar; Luc Beaulieu

2006-01-01

381

Modeling the Effects of Ionospheric Scintillations on LEO Satellite Communications  

Microsoft Academic Search

The fading statistics of the received signal caused by ionospheric scintillations for a given Earth station in low-Earth orbit (LEO) satellite communication network are studied using the recently available scintillation model. The path distribution from the Earth station to the satellite and the fading statistics of each path are considered. This time-varying channel model allows engineers to understand the effects

Sheng-Yi Li; C. H. Liu

2004-01-01

382

Results of the CALICE scintillator ECAL beamtest at DESY  

NASA Astrophysics Data System (ADS)

A prototype ILC scintillator-Tungsten electromagnetic calorimeter was constructed, with active layers consisting of scintillator strips, individually read out by MPPC devices. This prototype was exposed to positron beams at DESY in March 2007. Preliminary results of the analysis of the collected data are presented.

Jeans, Daniel; CALICE Collaboration

2009-04-01

383

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

384

Optimization of the Performance of Segmented Scintillators for Radiotherapy Imaging through Novel Binning Techniques  

PubMed Central

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 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 MTF, NPS, 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

2014-01-01

385

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

386

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

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

387

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

388

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

389

Measurement of ortho-positronium properties in liquid scintillators  

SciTech Connect

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.; Tonazzo, A. [Laboratoire AstroParticule et Cosmologie, Paris (France)] [Laboratoire AstroParticule et Cosmologie, Paris (France); Consolati, G. [Department of Aerospace Science and Technology, Politecnico di Milano (Italy)] [Department of Aerospace Science and Technology, Politecnico di Milano (Italy); Hans, S.; Yeh, M. [Brookhaven National Laboratory (United States)] [Brookhaven National Laboratory (United States); Jollet, C.; Meregaglia, A. [IPHC, Université de Strasbourg (France)] [IPHC, Université de Strasbourg (France)

2013-08-08

390

Comparison and analysis of tropospheric scintillation models for Northern Malaysia  

NASA Astrophysics Data System (ADS)

This paper presents the results of a study on tropospheric scintillation on satellite link that has been performed at University Sains Malaysia (USM) to obtain statistics of scintillation from the 12.255 GHz Superbird-C satellite with an elevation angle of 40.1°. Comparison of existing tropospheric scintillation models, namely the International Telecommunication Union (ITU), Direct Physical-Statistical Prediction (DPSP), Modeled Physical-Statistical Prediction (MPSP), Kamp-Tervonen-Salonen (KVS), and Karasawa were done for the measurement site. Then, cumulative distributions of measured scintillation intensity compared to the result of the prediction models for tropospheric scintillation were plotted and analyzed. ITU-R model gave the best prediction of 5.8% of error at 0.1% of fading time, compared with the other models.

Mandeep, J. S.; Yee, Anthony Cheng Chen; Abdullah, M.; Tariqul, M.

2011-07-01

391

Comparison of tropospheric scintillation prediction models of the Indonesian climate  

NASA Astrophysics Data System (ADS)

Tropospheric scintillation is a phenomenon that will cause signal degradation in satellite communication with low fade margin. Few studies of scintillation have been conducted in tropical regions. To analyze tropospheric scintillation, we obtain data from a satellite link installed at Bandung, Indonesia, at an elevation angle of 64.7° and a frequency of 12.247 GHz from 1999 to 2000. The data are processed and compared with the predictions of several well-known scintillation prediction models. From the analysis, we found that the ITU-R model gives the lowest error rate when predicting the scintillation intensity for fade at 4.68%. However, the model should be further tested using data from higher-frequency bands, such as the K and Ka bands, to verify the accuracy of the model.

Chen, Cheng Yee; Singh, Mandeep Jit

2014-12-01

392

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

393

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

394

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

395

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

396

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

397

Imaging of gamma emitters using scintillation cameras  

NASA Astrophysics Data System (ADS)

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

Ricard, Marcel

2004-07-01

398

Intermittency of laser scintillation over sea  

NASA Astrophysics Data System (ADS)

The intermittency in optical scintillation was theoretically studied and experimentally observed by laser propagation through the turbulent atmosphere over sea surface. It is found that the intermittent characteristics of the atmospheric turbulence repeat itself in optical irradiance fluctuations, then a method of the singularity measurement analysis was introduced and the intermittency index was presented to quantitatively evaluate the intermittency strength. Experiment results show that the intermittency index in laser scintillation is around 0.1 and varies a little compared with the significant variation of the turbulence strength, which had been approximately estimated at two orders of magnitude in a whole day. The dependence of the intermittency on the wavelength was further studied and the relationship was obtained using a multi-wavelength scintillometer. Generally, the intermittency indices display some differences at the different optical wavelengths, especially in strong turbulence. However, the wavelength dependence is not so notable that the intermittency indices are assumed to be equal within less than 10%, even the maximum error is no more than 20%. Moreover, some statistical results of the intermittency strength are also obtained from a long-term plan of laser propagating in coastal surroundings.

Zhu, Wenyue; Huang, Honghua; Rao, Ruizhong

2005-10-01

399

[Screening for diabetic retinopathy  

Microsoft Academic Search

Concurrent with the increasing incidence of diabetes mellitus, the incidence of diabetic retinopathy is also rising. Timely recognition with the aid of screening, followed by laser therapy, can prevent the greater part of the resulting visual impairment and blindness. However, many patients with diabetes are not screened or not screened adequately. The necessary screening frequency is annually or biannually, depending

W. W. Hartstra; F. Holleman; J. B. Hoekstra; R. O. Schlingemann

2007-01-01

400

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

ERIC Educational Resources Information Center

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

Department of Education, Washington, DC.

401

Risks of Cervical Cancer Screening  

MedlinePLUS

... Trials NCI Publications Español Cervical Cancer Screening (PDQ®) Risks of Cervical Cancer Screening Key Points for This ... your need for screening tests. Screening tests have risks. Decisions about screening tests can be difficult. Not ...

402

Plasma Screen Floating Mount  

SciTech Connect

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

403

Development and application of a novel nanophosphor scintillator for a low-dose, high-resolution digital X-ray imaging system  

Microsoft Academic Search

The recent development of a novel nanophosphor screen technology by Bhargava RN and associates (Nanocrystal technology, Briarcliff Manor, NY) started the exciting new phase of digital nanocrystal X-ray technology and its applications to the continually changing field of digital radiology. Charge-Coupled Devices (CCD) and Complimentary Metal Oxide Semiconductors (CMOS) traditionally use scintillators for conversion of X-ray photons to visible light,

Muralidhar Mupparapu; Rameshwar N. Bhargava; Satish Mullick; Steven R. Singer; Nikhil Taskar; Aleksey Yekimov

2005-01-01

404

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.

405

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.

406

CASTER - A Scintillator-Based Black Hole Finder Probe Based on Lanthanum Halide Scintillator  

NASA Astrophysics Data System (ADS)

The Black Hole Finder Probe is designed to survey the local Universe for black holes as part of NASA's Beyond Einstein program. CASTER (Coded Aperture Survey Telescope for Energetic Radiation) is a concept for a hard X-ray coded aperture imaging instrument operating in the 10-600 keV energy band with wide field of view and approximately 10 minute of arc angular resolution. With a detector area of approximately 6 m2, CASTER will obtain a 5? narrow line sensitivity at 511 keV approaching 10-7 photons cm-2sec-1. In order to fit a 6 m2 detector array into the constraints of a medium-sized ($400-600M) Beyond Einstein probe mission, CASTER uses newly developed lanthanum halide scintillator planes. We describe the CASTER design, demonstrate the sensitivity and resolution measured with cerium-doped lanthanum bromide and lanthanum chloride scintillators, and discuss the results expected from a CASTER mission.

Cherry, Michael; Bloser, P. F.; Budden, B. S.; Case, G. L.; Cravens, J. P.; Guzik, T. G.; Hurley, K. C.; Kippen, R. M.; Macri, J. R.; McConnell, M. L.; Miller, R. S.; Paciesas, W. S.; Ryan, J. M.; Schaefer, B. E.; Stacy, J. G.; Vestrand, W. T.; Wefel, J. P.

2006-09-01

407

Development of scintillation materials for medical imaging and other applications  

NASA Astrophysics Data System (ADS)

Scintillation materials that produce pulses of visible light in response to the absorption of energetic photons, neutrons, and charged particles, are widely used in various applications that require the detection of radiation. The discovery and development of new scintillators has accelerated in recent years, due in large part to their importance in medical imaging as well as in security and high energy physics applications. Better understanding of fundamental scintillation mechanisms as well as the roles played by defects and impurities have aided the development of new high performance scintillators for both gamma-ray and neutron detection. Although single crystals continue to dominate gamma-ray based imaging techniques, composite materials and transparent optical ceramics potentially offer advantages in terms of both synthesis processes and scintillation performance. A number of promising scintillator candidates have been identified during the last few years, and several are currently being actively developed for commercial production. Purification and control of raw materials and cost effective crystal growth processes can present significant challenges to the development of practical new scintillation materials.

Melcher, C. L.

2013-02-01

408

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

409

Tackling ionospheric scintillation threat to GNSS in Latin America  

NASA Astrophysics Data System (ADS)

Scintillations are rapid fluctuations in the phase and amplitude of transionospheric radio signals which are caused by small-scale plasma density irregularities in the ionosphere. In the case of the Global Navigation Satellite System (GNSS) receivers, scintillation can cause cycle slips, degrade the positioning accuracy and, when severe enough, can even lead to a complete loss of signal lock. Thus, the required levels of availability, accuracy, integrity and reliability for the GNSS applications may not be met during scintillation occurrence; this poses a major threat to a large number of modern-day GNSS-based applications. The whole of Latin America, Brazil in particular, is located in one of the regions most affected by scintillations. These effects will be exacerbated during solar maxima, the next predicted for 2013. This paper presents initial results from a research work aimed to tackle ionospheric scintillation effects for GNSS users in Latin America. This research is a part of the CIGALA (Concept for Ionospheric Scintillation Mitigation for Professional GNSS in Latin America) project, co-funded by the EC Seventh Framework Program and supervised by the GNSS Supervisory Authority (GSA), which aims to develop and test ionospheric scintillation countermeasures to be implemented in multi-frequency, multi-constellation GNSS receivers.

Veettil Sreeja, Vadakke; Aquino, Marcio; Forte, Biagio; Elmas, Zeynep; Hancock, Craig; de Franceschi, Giorgiana; Alfonsi, Lucilla; Spogli, Luca; Romano, Vincenzo; Bougard, Bruno; Francisco Galera Monico, Joao; Wernik, Andrzej W.; Sleewaegen, Jean-Marie; Cantó, Andrea; Ferreira da Silva, Elcia

2011-11-01

410

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

411

Characterization of high-latitude ionospheric scintillation of GPS signals  

NASA Astrophysics Data System (ADS)

paper presents statistical analysis of arctic auroral oval ionospheric scintillation events during the current solar maximum based on high-rate Global Positioning System data collected in Gakona, Alaska (62.39°N, 145.15°W) from August 2010 to March 2013. The objective is to gain a better understanding of the climatology and morphology of ionospheric scintillation in high-latitude regions. A scintillation event filter, multipath identification procedures, and other processes are applied to exclude nonscintillation related signal intensity and phase fluctuation and to extract scintillation events with S4 index above 0.12 and phase sigma above 6° from over 657 days of data. A total of over 5800 scintillation events were identified; most of them show phase fluctuations, only 10% of the phase fluctuations are accompanied by weak amplitude scintillation. Based on the occurrence time, signal direction of arrival, intensity, and duration of these scintillation events and the solar and geomagnetic activities associated with these events, diurnal, seasonal, spatial, and solar activity dependencies are derived and presented in the paper.

Jiao, Yu; Morton, Yu T.; Taylor, Steven; Pelgrum, Wouter

2013-11-01

412

Scintillation modeling for GPS-Wide Area Augmentation System receivers  

NASA Astrophysics Data System (ADS)

A scintillation signal model and a Global Positioning System (GPS)-Wide Area Augmentation System (WAAS) receiver model are developed. The scintillation signal model is based on a Nakagami-m distribution for intensity and a Gaussian distribution with zero mean for phase. The GPS-WAAS receiver model includes Link 1 (L1) GPS and WAAS carrier-and C/A-code-tracking loops, as well as semicodeless Link 2 (L2) carrier and Y-code tracking capabilities. The results show that noncoherent delay locked loops (DLLs) typically used for code tracking are very robust to both amplitude and phase scintillation. Carrier-phase-tracking loops are much more susceptible to scintillation, and the signal-to-noise threshold for reliable carrier tracking is very dependent on the scintillation strength. Fortunately, it appears that the worst case scintillation encountered at midlatitudes, including the United States, does not significantly impact L1 carrier-tracking performance. Semicodeless tracking of the L2 carrier is shown to be very fragile. Even weak scintillation can cause loss of L2 carrier lock for low-elevation satellites.

Hegarty, Christopher; El-Arini, M. Bakry; Kim, Taehwan; Ericson, Swen

2001-09-01

413

A Generic Receiver Tracking Model for GPS Ionospheric Amplitude Scintillation  

NASA Astrophysics Data System (ADS)

Ionospheric scintillations result in rapid variations in phase and amplitude of the radio signal, which propagates through the ionosphere. Depending on the temporal and spatial situation, the scintillation can represent a problem in the availability and precision of the Global Navigation Satellite Systems (GNSS). Scintillations affect the receiver performance, specially the tracking loop level. Depending on the scintillation level, the receiver might increase the measurement errors or even can lead to a loss of lock of the carrier and code loops. In extreme cases, the scintillation can result in full disrupting of the receiver. In this work we introduce a generic model to evaluate the effects of ionospheric amplitude scintillation on GPS receiver tracking loops. This model is based on ?-? distribution, which can be seen as a generalized fading model, that includes a variety of distributions such as Gamma, Nakagami-m, Exponential, Weibull, one-sided Gaussian and Rayleigh. Differently from the model based only on Nakagami-m, this one is not limited to S4< 0,71 which allows using it to predict amplitude scintillation effects for stronger scenarios. The estimation of ?-? coefficients, the empirical parameterization based on field measurements and the typical values estimated based on observations made during the last solar maximum are presented and discussed.

Paula, E. R.; Moraes, A. D.; Perrella, W. J.; Galera Monico, J. F.

2012-12-01

414

Novel polysiloxane-based scintillators for neutron detection.  

PubMed

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

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

2011-02-01

415

Global analysis of scintillation variance: Indication of gravity wave breaking in the polar winter upper stratosphere  

Microsoft Academic Search

Stellar scintillations observed through the Earth atmosphere are caused by air density irregularities generated mainly by internal gravity waves and turbulence. We present global analysis of scintillation variance in two seasons of year 2003 based on GOMOS\\/Envisat fast photometer measurements. Scintillation variance can serve as a qualitative indicator of intensity of small-scale processes in the stratosphere. Strong increase of scintillation

V. F. Sofieva; E. Kyrölä; S. Hassinen; L. Backman; J. Tamminen; A. Seppälä; L. Thölix; A. S. Gurvich; V. Kan; F. Dalaudier; A. Hauchecorne; J.-L. Bertaux; D. Fussen; F. Vanhellemont; O. Fanton d' Andon; G. Barrot; A. Mangin; M. Guirlet; T. Fehr; P. Snoeij; L. Saavedra; R. Koopman; R. Fraisse

2007-01-01

416

Digital Measures screen changes 1 Digital Measures screen changes 2  

E-print Network

Digital Measures screen changes 1 #12; Digital Measures screen changes 2 #12; Digital Measures screen changes 3 #12; Digital Measures screen changes 4 #12; Digital Measures screen changes 5 #12; Digital Measures screen changes 6 #12; Digital Measures screen changes 7 #12

Barrash, Warren

417

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

ERIC Educational Resources Information Center

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

Howard, Patricia

2005-01-01

418

FERPA Training Guide FERPA Training Steps  

E-print Network

FERPA Training Guide 1 FERPA Training Steps Graduate committee chairs and co-chairs are encouraged-time FERPA training via TrainTraq (if not previously completed). When trying to access the Graduate Committee Degree Evaluation too, the following screen will display if you have not completed FERPA training

419

Syllabus Information Depiction System (SIDS) user's guide  

SciTech Connect

The Syllabus Information Depiction System (SIDS) is an automated tool designed to track the aircrew training syllabi of the Marine Corps. This report is the User's Manual for this data base system, providing users with instructions to help them use the system more efficiently. This document contains printed screen layouts that will guide the user step-by-step through the written instructions.

Waterman, D.K.; Skinner, N.L.

1987-10-01

420

Sound and Light from Fractures in Scintillators  

NASA Astrophysics Data System (ADS)

Prompted by intriguing events observed in certain particle-physics searches for rare events, we study light and acoustic emission simultaneously in some inorganic scintillators subject to mechanical stress. We observe mechanoluminescence in Bi4Ge3O12, CdWO4, and ZnWO4, in various mechanical configurations at room temperature and ambient pressure. We analyze the temporal and amplitude correlations between the light emission and the acoustic emission during fracture. A novel application of the precise energy calibration of Bi4Ge3O12 provided by radioactive sources allows us to deduce that the fraction of elastic energy converted to light is at least 3×10-5.

Tantot, A.; Santucci, S.; Ramos, O.; Deschanel, S.; Verdier, M.-A.; Mony, E.; Wei, Y.; Ciliberto, S.; Vanel, L.; Di Stefano, P. C. F.

2013-10-01

421

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

422

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

423

Prompt Fission ?-rays Measured Using Liquid Scintillators  

NASA Astrophysics Data System (ADS)

The prompt ?-ray spectra from 235U(n,f) at incident energies of 1 to 20 MeV and for 235Cf(s.f.) were measured up to 4 MeV in coincidence with two parallel plate avalanche counters and the liquid scintillator array FIGARO. The unfolded ?-ray spectra from 1-4 MeV using the single value decomposition and iterative Bayesian techniques for the incident neutron energy regions corresponding to the first, second and third chance fissions were found to nearly identical and similar to the distribution from the spontaneous fission of 252Cf. General agreement with the ?-ray distributions from fission was also found with previous measurements.

Kwan, E.; Wu, C. Y.; Haight, R. C.; Lee, H. Y.; Bredeweg, T. A.; Chyzh, A.; Devlin, M.; Fotiades, N.; Gostic, J. M.; Henderson, R. A.; Jandel, M.; Laptev, A.; Nelson, R. O.; O'Donnell, J. M.; Perdue, B. A.; Taddeucci, T. N.; Ullmann, J. L.; Wender, S. A.

2014-05-01

424

Uranium scintillator calorimeter at the CERN ISR  

SciTech Connect

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

Gordon, H; Killian, T; Ludlam, T

1980-01-01

425

The CALICE hadron scintillator tile calorimeter prototype  

NASA Astrophysics Data System (ADS)

The CALICE Collaboration develops high granularity calorimeters to achieve excellent energy resolution at ILC. One type is a four million channel scintillator tile Hadron Calorimeter (AHCAL) read out with novel photodetectors—Silicon PhotoMultipliers (SiPM). A 1 m 3 prototype with 7608 channels was built in order to test the Particle Flow concept and to gain experience with the novel techniques. The prototype and MEPhI/Pulsar SiPMs have demonstrated excellent performance and stability during several months of testing at CERN and FNAL in 2006-2008. Less than 0.08% of SiPMs are broken. The SiPM calibration and monitoring procedures have been developed. Improved SiPMs have been developed by CPTA for the next engineering prototype and their properties are discussed. This prototype will have very slim sensitive planes with electronics inside. It addresses all engineering issues relevant to the real calorimeter at ILC.

Buanes, T.; Danilov, M.; Eigen, G.; Göttlicher, P.; Markin, O.; Reinecke, M.; Tarkovsky, E.; Calice Collaboration

2010-11-01

426

Scintillating Ceramics Based on Zinc Oxide  

NASA Astrophysics Data System (ADS)

Optical transparent ceramics were manufactured from different ZnO powders by uniaxial hot pressing method. Structural, optical and scintillating characteristics of the ceramics have been studied. For all samples, an increase in grain size by one or two decimal order in ceramics as compared to that of the initial powder was observed. Undoped ZnO ceramics shows a high light output 28 500 ± 800 photons/MeV, decay constant ~ 1 ?s, a very low afterglow, optical transparency closed to that for single crystal and a linearity of the relative light output in range 35-652 keV. Introduction of Li in ZnO decreases decay time constant of the ceramics. ZnO:Ga ceramics show an ultrafast decay, 0.7 ns, not high light output: ~ 1000 photons/MeV, and a low optical transparency.

Rodnyi, P. A.; Gorokhova, E. I.; Chernenko, K. A.; Khoduk, I. V.

2012-08-01

427

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

428

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.

429

Measurement of the liquid scintillator nonlinear energy response to electron  

NASA Astrophysics Data System (ADS)

Nonlinearity of the liquid scintillator energy response is a key to measuring the neutrino energy spectrum in reactor neutrino experiments such as Daya Bay and JUNO. We measured the nonlinearity of the linear alkyl benzene based liquid scintillator in the laboratory, which is used in Daya Bay and will be used in JUNO, via the Compton scattering process. By tagging the scattered gamma from the liquid scintillator sample simultaneously at seven angles, the instability of the system was largely cancelled. The accurately measured nonlinearity will improve the precision of the ?13, ?m2, and reactor neutrino spectrum measurements at Daya Bay.

Zhang, Fei-Hong; Yu, Bo-Xiang; Hu, Wei; Yang, Ma-Sheng; Cao, Guo-Fu; Cao, Jun; Zhou, Li

2015-01-01

430

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

431

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

432

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

433

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

434

Prototype of scintillating fibre vertex detector with CCD readout  

NASA Astrophysics Data System (ADS)

A prototype of a vertex detector with polystyrene scintillating fibres and cells with liquid scintillator using CCD readout has been studied. For the polystyrene fibres of 150 ?m diameter the number of clusters per unit track length is n0 = 3.17 mm -1 with a straight-line rms residual ? p ? 70 ? m and a track impact parameter precision ? p ? 35 ? m. For the detector with the cells with liquid scintillator n0 is obtained to be 3.10 mm -1 and ? liq ? 68 ? m, ? liq ? 33 ? m. The two-track resolution is 110 ?m.

Bamburov, N. S.; Denisov, A. G.; Golovkin, S. V.; Gorin, A. M.; Govorun, V. N.; Kaimachnikov, S. V.; Kazakov, P. N.; Kozarenko, E. N.; Manuilov, I. V.; Medvedkov, A. M.; Petrenko, S. V.; Rykalin, V. I.; Ryazantsev, A. V.; Sakharov, V. P.; Vasil'chenko, V. G.

1990-04-01

435

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

436

Border Screening for SARS  

PubMed Central

With the rapid international spread of severe acute respiratory syndrome (SARS) from March through May 2003, Canada introduced various measures to screen airplane passengers at selected airports for symptoms and signs of SARS. The World Health Organization requested that all affected areas screen departing passengers for SARS symptoms. In spite of intensive screening, no SARS cases were detected. SARS has an extremely low prevalence, and the positive predictive value of screening is essentially zero. Canadian screening results raise questions about the effectiveness of available screening measures for SARS at international borders. PMID:15705315

King, Arlene; de Jong, Dick; Bodie-Collins, Margaret; Squires, Susan G.; Tam, Theresa WS

2005-01-01

437

Investigating the response of scintillators for the detection of laser accelerated protons  

NASA Astrophysics Data System (ADS)

Radiation pressure acceleration with ultraintense laser pulses presents an exciting new scheme for obtaining energetic protons from a gas jet target. One of the advantages conferred by using a gaseous laser and target is the potential for a fast (1 Hz) repetition rate. This requires diagnostics which are not only comprehensive for a single shot, but also capable of 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), CsI:Tl, and a polyvinyl toluene (PVT) screen to protons in the 2-12 MeV range using a CCD camera. We have calibrated the luminescent yield in terms of photons emitted per incident proton for each scintillator. We also discuss photon scattering in each and determine its impact on their respective resolutions. In addition, we consider the impact of radiation intensity on the materials, including radiation damage and the presence of an afterglow. Our analysis reveals a near order of magnitude greater yield from Chromox in response to proton beams in this energy range. Moreover, Chromox displays improved radiation resistance, making it the best choice for a flexible diagnostic tool

Cook, Nathan; Tresca, Olivier; Yakimenko, Vitaly

2013-04-01

438

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

439

Breast cancer screening: The role of attachment.  

PubMed

Attachment style is the dispositional way in which a person relates to others, and differences in attachment characteristics may offer insight into why many women do not adhere to breast screening guidelines. While mammograms involve contact with medical professionals, breast self-examination (BSE) does not, and may be preferable for women who dislike interpersonal vulnerability. As such, differences in the attachment characteristics that predict mammography versus BSE utilisation may indicate whether attachment related motivations are relevant to both interpersonal examinations and independent self-care behaviours. The current report examined how attachment dimensions predicted the frequency of mammography and BSE in a sample of 1204 ethnically diverse women from Brooklyn, New York. Participants completed measures of mammography and BSE frequency, and attachment, together with demographic, health care context and emotional predictors of screening. Multiple regressions showed that attachment dimensions predicted both mammography and BSE screening even when controlling for established predictors and emotion relevant variables. As hypothesised, fearful avoidance predicted fewer mammograms and BSEs, while preoccupation predicted more frequent BSEs. Consistent with some prior work in male cancer screening, greater attachment security also predicted fewer mammograms while degree of dismissiveness was not associated with screening frequencies. Understanding the psychosocial predictors of screening may help identify low screeners, and guide the development of targeted interventions that are better suited to the interpersonal preferences of older women. PMID:25192017

Tuck, Natalie L; Consedine, Nathan S

2015-06-01

440

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

NASA Astrophysics Data System (ADS)

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 1011 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

2013-05-01

441

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

442

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

443

Comparison of Plastic and NaI(Tl) Scintillators for Vehicle Portal Monitor Applications  

SciTech Connect

Experimental data and computer simulations are presented for gamma-ray detection by vehicle portal monitors for homeland security applications at international borders. The experiments and simulations use spectral processing of gamma rays from various sources (241Am, 57Co, 133Ba, 137Cs, 60Co) and background to provide data for comparing plastic and NaI(Tl) detectors. The effects of gamma-ray scattering in cargo are also examined. Plastic scintillators are well suited for primary screening of gamma-ray sources because of their large size and low cost. Sodium iodide is preferable to plastic for applications of isotope identification based on gamma-ray spectrometry. Some applications may benefit from integrating features from both types of detectors.

Stromswold, David C.; Siciliano, Edward R.; Schweppe, John E.; Ely, James H.; Milbrath, Brian D.; Kouzes, Richard T.; Geelhood, Bruce D.

2003-10-31

444

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.

445

Stretching Screens and Imaginations.  

ERIC Educational Resources Information Center

Secondary students utilize a simplified technique to make silk screen prints, which can be printed onto T-shirts. The only materials needed from art suppliers are a few squeegees and a few yards of polyester screen mesh. (RM)

Douthwaite, Shelaugh

1983-01-01

446

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

447

Lung Cancer Screening  

PubMed Central

Lung cancer is the leading cause of cancer death. Although smoking prevention and cessation programs have decreased lung cancer mortality, there remains a large at-risk population. Dismal long-term survival rates persist despite improvements in diagnosis, staging, and treatment. Early efforts to identify an effective screening test have been unsuccessful. Recent advances in multidetector computed tomography have allowed screening studies using low-dose computed tomography (LDCT) to be performed. This set the stage for the National Lung Screening Trial that found that annual LDCT screening benefits individuals at high risk for lung cancer. An understanding of the harmful effects of lung cancer screening is required to help maximize the benefits and decrease the risks of a lung cancer screening program. Although many questions remain regarding LDCT screening, a comprehensive lung cancer screening program of high-risk individuals will increase detection of preclinical and potentially curable disease, creating a new model of lung cancer surveillance and management. PMID:24436526

Gutierrez, Antonio; Suh, Robert; Abtin, Fereidoun; Genshaft, Scott; Brown, Kathleen

2013-01-01

448

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

449

Screening for Prostate Cancer  

MedlinePLUS

Screening for Prostate Cancer: A Guidance Statement From the Clinical Guidelines Committee of the American College of Physicians The full report is titled “Screening for Prostate Cancer: A Guidance Statement From the Clinical Guidelines ...

450

Prostate Cancer Screening  

MedlinePLUS

The prostate is the gland below a man's bladder that produces fluid for semen. Cancer screening is looking for ... treat. There is no standard screening test for prostate cancer. Researchers are studying different tests to find ...

451

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

452

Newborn screening tests  

MedlinePLUS

... March of Dimes and the American College of Medical Genetics suggest more than two dozen additional tests. The ... Saunders Elsevier; 2011:chap 707. American College of Medical Genetics Newborn Screening Expert Group. Newborn screening: toward a ...

453

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

454

The effects of dissolved methane upon liquid argon scintillation light  

NASA Astrophysics Data System (ADS)

In this paper we report on measurements of the effects of dissolved methane upon argon scintillation light. We monitor the light yield from an alpha source held 20 cm from a cryogenic photomultiplier tube (PMT) assembly as methane is injected into a high-purity liquid argon volume. We observe significant suppression of the scintillation light yield by dissolved methane at the 10 part per billion (ppb) level. By examining the late scintillation light time constant, we determine that this loss is caused by an absorption process and also see some evidence of methane-induced scintillation quenching at higher concentrations (50-100 ppb). Using a second PMT assembly we look for visible re-emission features from the dissolved methane which have been reported in gas-phase argon methane mixtures, and we find no evidence of visible re-emission from liquid-phase argon methane mixtures at concentrations between 10 ppb and 0.1%.

Jones, B. J. P.; Alexander, T.; Back, H. O.; Collin, G.; Conrad, J. M.; Greene, A.; Katori, T.; Pordes, S.; Toups, M.

2013-12-01

455

Experimental efforts and results in finding new heavy scintillators  

SciTech Connect

New heavy scintillators are being discovered with increasing frequency. In recent years NaI(Tl) (with its high light output and energy resolution) has been joined by BGO (with its high stopping power), BaF{sub 2} (with its excellent timing resolution), and CeF{sub 3} (with its speed and short Moliere radius). More than 10 potentially useful scintillators have been under development in the past five years, such as PbSO{sub 4} and Lu{sub 2}SiO{sub 5}(Ce). We tabulate the characteristics of these and other scintillators, including wavelength, luminous efficiency, decay time, and initial intensity. We describe a search strategy and the prospects for finding the ``ideal`` heavy scintillator, which would combine the light output of NaI(Tl) and CsI(Tl), the stopping power of BGO, and the speed of BaF{sub 2} and ZnO(Ga).

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

1992-09-01

456

21 CFR 892.1100 - Scintillation (gamma) camera.  

Code of Federal Regulations, 2012 CFR

...scintillation (gamma) camera is a device intended to image the distribution of radionuclides in the body by means of a photon radiation detector. This generic type of device may include signal analysis and display equipment, patient and equipment...

2012-04-01

457

21 CFR 892.1100 - Scintillation (gamma) camera.  

Code of Federal Regulations, 2011 CFR

...scintillation (gamma) camera is a device intended to image the distribution of radionuclides in the body by means of a photon radiation detector. This generic type of device may include signal analysis and display equipment, patient and equipment...

2011-04-01

458

21 CFR 892.1100 - Scintillation (gamma) camera.  

Code of Federal Regulations, 2013 CFR

...scintillation (gamma) camera is a device intended to image the distribution of radionuclides in the body by means of a photon radiation detector. This generic type of device may include signal analysis and display equipment, patient and equipment...

2013-04-01

459

21 CFR 892.1100 - Scintillation (gamma) camera.  

Code of Federal Regulations, 2014 CFR

...scintillation (gamma) camera is a device intended to image the distribution of radionuclides in the body by means of a photon radiation detector. This generic type of device may include signal analysis and display equipment, patient and equipment...

2014-04-01

460

Study of the Sensitivity of Plastic Scintillator to Fast Neutrons  

NASA Astrophysics Data System (ADS)

The Mu2e experiment at Fermilab plans to use a two-out-of-three coincident requirement in a plastic scintillator based detector to veto cosmic ray events. This veto system must operate efficiently in a high-radiation environment. In this investigation, three plastic scintillator bars containing wavelength-shifting fibers represent the veto system. These bars were placed in series in front of a deuterium-deuterium neutron generator, which produced fast neutrons of approximately 2.8MeV. Multi-anode photomultiplier tubes read out the light from the fibers. The collected data was analyzed to determine the rate of interaction, approximate amount of energy deposited, and numerous other aspects of the neutrons' interactions. The rate of coincidental and correlated hits in multiple scintillator bars was the primary investigation, in order to further understand the sensitivity of