These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Absolute charge calibration of scintillating screens for relativistic electron detection  

SciTech Connect

We report on new charge calibrations and linearity tests with high-dynamic range for eight different scintillating screens typically used for the detection of relativistic electrons from laser-plasma based acceleration schemes. The absolute charge calibration was done with picosecond electron bunches at the ELBE linear accelerator in Dresden. The lower detection limit in our setup for the most sensitive scintillating screen (KODAK Biomax MS) was 10 fC/mm{sup 2}. The screens showed a linear photon-to-charge dependency over several orders of magnitude. An onset of saturation effects starting around 10-100 pC/mm{sup 2} was found for some of the screens. Additionally, a constant light source was employed as a luminosity reference to simplify the transfer of a one-time absolute calibration to different experimental setups.

Buck, A.; Popp, A.; Schmid, K.; Karsch, S.; Krausz, F. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Ludwig-Maximilians-Universitaet Muenchen, Am Coulombwall 1, D-85748 Garching (Germany); Zeil, K.; Jochmann, A.; Kraft, S. D.; Sauerbrey, R.; Cowan, T.; Schramm, U. [Forschungszentrum Dresden Rossendorf, Bautzner Landstrasse 400, D-01328 Dresden (Germany); Hidding, B.; Kudyakov, T. [Institut fuer Laser und Plasmaphysik, Heinrich-Heine-Universitaet Duesseldorf, Universitaetsstrasse 1, D-40225 Duesseldorf (Germany); Sears, C. M. S.; Veisz, L. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Pawelke, J. [Forschungszentrum Dresden Rossendorf, Bautzner Landstrasse 400, D-01328 Dresden (Germany); Oncoray, Technische Universitaet Dresden, Fetscher Strasse 74, D-01307 Dresden (Germany)

2010-03-15

2

Theory of thin screen scintillations for a spherical wave  

NASA Technical Reports Server (NTRS)

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

Lee, L. C.

1976-01-01

3

Optimization of screening for radioactivity in urine by liquid scintillation.  

SciTech Connect

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

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

2007-08-01

4

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

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

PubMed

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

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

2010-10-01

6

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.

7

Measurement and Monte Carlo modeling of the spatial response of scintillation screens  

NASA Astrophysics Data System (ADS)

In this article, we propose a detailed protocol to carry out measurements of the spatial response of scintillation screens and to assess the agreement with simulated results. The experimental measurements have been carried out using a practical implementation of the slit method. A Monte Carlo simulation model of scintillator screens, implemented with the toolkit Geant4, has been used to study the influence of the acquisition setup parameters and to compare with the experimental results. An algorithm of global stochastic optimization based on a localized random search method has been implemented to adjust the optical parameters (optical scattering and absorption coefficients). The algorithm has been tested for different X-ray tube voltages (40, 70 and 100 kV). A satisfactory convergence between the results simulated with the optimized model and the experimental measurements is obtained.

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

2007-11-01

8

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

9

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...

10

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

11

Student Information System Screen and Website Guide Lite Version  

E-print Network

.................................................................................................... 8 RSU1 Screen .................................................................................................... 9 RSU2 Screen

12

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

SciTech Connect

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

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

2010-04-02

13

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

NASA Astrophysics Data System (ADS)

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

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

2011-01-01

14

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

15

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

16

Use of a laser guide to reduce screening time for the dynamic hip screw  

Microsoft Academic Search

A prospective, randomized study was used to evaluate a laser guide to aim the image intensifier during the treatment of 52 patients with intertrochanteric fractures of the proximal femur using a dynamic hip screw. The laser guide reduces the fluoroscopic screening time by 40 per cent (P < 0.05). We conclude that laser aiming of the image intensifier has a

A. H. N. Robinson; M. Moiz; J. P. Hallett

1996-01-01

17

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

18

TimeClock Plus 6.0 On-Screen TimeC1ock Essentials Usability Guide  

E-print Network

TimeClock Plus 6.0 On-Screen TimeC1ock Essentials Usability Guide Opening On-Screen TimeClock 1. 2. Launch On-Screen TimeClock (Start > Programs/All Programs > TimeClock Plus 6.0 > On-Screen Time and click OK. 5. Click OK on the successful message. On-Screen TimeClock Essentials Usability Guide © Data

Long, Nicholas

19

A Guide for Vision Screening in California Public Schools.  

ERIC Educational Resources Information Center

This manual for district and school health personnel contains guidelines to facilitate the planning and implementation of vision screening programs in California public schools so that all students may benefit from optimal use of their sense of sight. The major program objectives, the legal basis, minimum requirements, and authorized personnel are

California State Dept. of Education, Sacramento. Office of Curriculum Services.

20

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

21

Algorithmic guided screening of drug combinations of arbitrary size for activity against cancer cells  

E-print Network

Algorithmic guided screening of drug combinations of arbitrary size for activity against cancer Imaging, and 3 Systems Biology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas; 4 Institute, Santa Fe, New Mexico Abstract The standard treatment for most advanced cancers is multidrug

Popova, Elmira

22

A simple laser guide to reduce the screening time during the insertion of dynamic hip screws  

Microsoft Academic Search

A simple laser pointer can be used to guide the radiographer to position the image intensifier during the insertion of a dynamic hip screw in the treatment of fractures of the trochanteric area of the proximal femur. This significantly reduces the screening time and, by implication, the amount of radiation for the theatre staff and patient.

K. S. Conn; J. P. Hallett

1998-01-01

23

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

24

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

25

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

26

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

PubMed Central

Pro-survival members of the Bcl-2 protein family inhibit cell death by binding short helical BH3 motifs in pro-apoptotic proteins. Mammalian pro-survival proteins Bcl-xL, Bcl-2, Bcl-w, Mcl-1 and Bfl-1 bind with varying affinities and specificities to native BH3 motifs, engineered peptides and small molecules. Biophysical studies have determined interaction patterns for these proteins, particularly for the most-studied family members Bcl-xL and Mcl-1. Bfl-1 is a pro-survival protein implicated in preventing apoptosis in leukemia, lymphoma and melanoma. Although Bfl-1 is a promising therapeutic target, relatively little is known about its binding preferences. We explored the binding of Bfl-1 to BH3-like peptides by screening a peptide library that was designed to sample a high degree of relevant sequence diversity. Screening using yeast-surface display led to several novel high-affinity Bfl-1 binders and to thousands of putative binders identified through deep sequencing. Further screening for specificity led to identification of a peptide that bound to Bfl-1 with Kd < 1 nM and very slow dissociation from Bfl-1 compared to other pro-survival Bcl-2 family members. A point mutation in this sequence gave a peptide with ~50 nM affinity for Bfl-1 that was selective for Bfl-1 in equilibrium binding assays. Analysis of engineered Bfl-1 binders deepens our understanding of how the binding profiles of pro-survival proteins differ, and may guide the development of targeted Bfl-1 inhibitors. PMID:23363053

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

2013-01-01

27

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

PubMed

Pro-survival members of the Bcl-2 protein family inhibit cell death by binding short helical BH3 motifs in pro-apoptotic proteins. Mammalian pro-survival proteins Bcl-x(L), Bcl-2, Bcl-w, Mcl-1, and Bfl-1 bind with varying affinities and specificities to native BH3 motifs, engineered peptides, and small molecules. Biophysical studies have determined interaction patterns for these proteins, particularly for the most-studied family members Bcl-x(L) and Mcl-1. Bfl-1 is a pro-survival protein implicated in preventing apoptosis in leukemia, lymphoma, and melanoma. Although Bfl-1 is a promising therapeutic target, relatively little is known about its binding preferences. We explored the binding of Bfl-1 to BH3-like peptides by screening a peptide library that was designed to sample a high degree of relevant sequence diversity. Screening using yeast-surface display led to several novel high-affinity Bfl-1 binders and to thousands of putative binders identified through deep sequencing. Further screening for specificity led to identification of a peptide that bound to Bfl-1 with K(d) < 1 nM and very slow dissociation from Bfl-1 compared to other pro-survival Bcl-2 family members. A point mutation in this sequence gave a peptide with ~50 nM affinity for Bfl-1 that was selective for Bfl-1 in equilibrium binding assays. Analysis of engineered Bfl-1 binders deepens our understanding of how the binding profiles of pro-survival proteins differ and may guide the development of targeted Bfl-1 inhibitors. PMID:23363053

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

2013-04-19

28

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...

29

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

30

Halide Scintillators  

Microsoft Academic Search

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

E. V. D. Van Loef

2003-01-01

31

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

32

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

33

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

34

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

35

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.

36

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

PubMed Central

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

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

2011-01-01

37

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

Microsoft Academic Search

BackgroundLarge-scale RNAi-based screens are playing a critical role in defining sets of genes that regulate specific cellular processes.\\u000a Numerous screens have been completed and in some cases more than one screen has examined the same cellular process, enabling\\u000a a direct comparison of the genes identified in separate screens. Surprisingly, the overlap observed between the results of\\u000a similar screens is low,

Stephen T Guest; Jingkai Yu; Dongmei Liu; Julie A Hines; Maria A Kashat; Russell L Finley Jr

2011-01-01

38

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

PubMed Central

Kinetic Target-Guided Synthesis (TGS) and in situ click chemistry are among unconventional discovery strategies having the potential to streamline the development of protein-protein interaction modulators (PPIMs). In kinetic TGS and in situ click chemistry, the target is directly involved in the assembly of its own potent, bidentate ligand from a pool of reactive fragments. Herein, we report the use and validation of kinetic TGS based on the sulfo-click reaction between thio acids and sulfonyl azides as a screening and synthesis platform for the identification of high-quality PPIMs. Starting from a randomly designed library consisting of 9 thio acids and 9 sulfonyl azides leading to 81 potential acylsulfonamides, the target protein, Bcl-XL selectively assembled four PPIMs, acylsulfonamides SZ4TA2, SZ7TA2, SZ9TA1, and SZ9TA5, which have been shown to modulate Bcl-XL/BH3 interactions. To further investigate the Bcl-XL templation effect, control experiments were carried out using two mutants of Bcl-XL. In one mutant, phenylalanine Phe131 and aspartic acid Asp133, which are critical for the BH3 domain binding, have been substituted by alanines, while arginine Arg139, a residue identified to play a crucial role in the binding of ABT-737, a BH3 mimetic, has been replaced by an alanine in the other mutant. Incubation of these mutants with the reactive fragments and subsequent LC/MS-SIM analysis confirmed that these building block combinations yield the corresponding acylsulfonamides at the BH3 binding site, the actual hot spot of Bcl-XL. These results validate kinetic TGS using the sulfo-click reaction as a valuable tool for the straightforward identification of high-quality PPIMs. PMID:21506574

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

2011-01-01

39

Scintillating Stars  

NSDL National Science Digital Library

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

Riddle, Bob

2003-02-01

40

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

41

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

PubMed Central

Background Large-scale RNAi-based screens are playing a critical role in defining sets of genes that regulate specific cellular processes. Numerous screens have been completed and in some cases more than one screen has examined the same cellular process, enabling a direct comparison of the genes identified in separate screens. Surprisingly, the overlap observed between the results of similar screens is low, suggesting that RNAi screens have relatively high levels of false positives, false negatives, or both. Results We re-examined genes that were identified in two previous RNAi-based cell cycle screens to identify potential false positives and false negatives. We were able to confirm many of the originally observed phenotypes and to reveal many likely false positives. To identify potential false negatives from the previous screens, we used protein interaction networks to select genes for re-screening. We demonstrate cell cycle phenotypes for a significant number of these genes and show that the protein interaction network is an efficient predictor of new cell cycle regulators. Combining our results with the results of the previous screens identified a group of validated, high-confidence cell cycle/cell survival regulators. Examination of the subset of genes from this group that regulate the G1/S cell cycle transition revealed the presence of multiple members of three structurally related protein complexes: the eukaryotic translation initiation factor 3 (eIF3) complex, the COP9 signalosome, and the proteasome lid. Using a combinatorial RNAi approach, we show that while all three of these complexes are required for Cdk2/Cyclin E activity, the eIF3 complex is specifically required for some other step that limits the G1/S cell cycle transition. Conclusions Our results show that false positives and false negatives each play a significant role in the lack of overlap that is observed between similar large-scale RNAi-based screens. Our results also show that protein network data can be used to minimize false negatives and false positives and to more efficiently identify comprehensive sets of regulators for a process. Finally, our data provides a high confidence set of genes that are likely to play key roles in regulating the cell cycle or cell survival. PMID:21548953

2011-01-01

42

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

Microsoft Academic Search

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

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

2006-01-01

43

Discovery of indolotryptoline antiproliferative agents by homology-guided metagenomic screening  

PubMed Central

Natural product discovery by random screening of broth extracts derived from cultured bacteria often suffers from high rates of redundant isolation, making it ever more challenging to identify novel biologically interesting natural products. Here we show that homology-based screening of soil metagenomes can be used to specifically target the discovery of new members of traditionally rare, biomedically relevant natural product families. Phylogenetic analysis of oxy-tryptophan dimerization gene homologs found within a large soil DNA library enabled the identification and recovery of a unique tryptophan dimerization biosynthetic gene cluster, which we have termed the bor cluster. When heterologously expressed in Streptomyces albus, this cluster produced an indolotryptoline antiproliferative agent with CaMKII? kinase inhibitory activity (borregomycin A), along with several dihydroxyindolocarbazole anticancer/antibiotics (borregomycins BD). Similar homology-based screening of large environmental DNA libraries is likely to permit the directed discovery of new members within other previously rare families of bioactive natural products. PMID:23302687

Chang, Fang-Yuan; Brady, Sean F.

2013-01-01

44

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

45

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, Ren; Beaulieu, Luc

2005-07-01

46

Baseline for a Nordtest method. Reliability stress screening of components. A guide for component users  

NASA Astrophysics Data System (ADS)

A method for reliability stress screening (RSS) of components has been developed and is proposed to form a baseline for a Nordtest-method. Before issuance as a Nordtest-method, it is proposed to supplement this report regarding possible failure modes and to make some editorial changes. The development work has been done in cooperation between the Swedish National Testing and Research Institute (SP) and Elektronikcentralen (EC) and was financed by Nordtest. The method makes use of methods described in IEC standard 1163. It is complementary to Nordtest-method NT ELEC 018 which defines a method for RSS of printed wiring assemblies. The purpose of the method is to give guidance to the component user and equipment manufacturer for the specification and the performance of screening for different cases. Five cases based on the users' different aims for the screening are defined in the method. Examples of the design of a screening program are given for 4 different component generic families. These are chosen as being the component families with the highest rate of early failures as defined by a questionnaire performed during the work with the Nordtest-method NT ELEC 018.

Boerjesson, Arne; Loll, Valter; Kristensen, Allan Moller

47

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.  

PubMed

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. PMID:18196785

Krishnan, Sunil; Briere, Tina Marie; Dong, Lei; Murthy, Ravi; Ng, Chaan; Balter, Peter; Mohan, Radhe; Gillin, Michael T; Beddar, A Sam

2007-12-01

48

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

Microsoft Academic Search

The Facility Energy Decision Screening (FEDS) Model is under development at Pacific Northwest Laboratory (PNL) for the US DOE Federal Energy Management Program (DOE-FEMP) and the US Army Construction Engineering REsearch Laboratory (USA-CERL). FEDS is a multi-level energy analysis software system designed to provide a comprehensive approach to fuel-neutral, technology-independent, integrated (energy) resource planning and acquisition. The FEDS system includes

1995-01-01

49

Accelerated discovery of novel benzodiazepine ligands by experiment-guided virtual screening.  

PubMed

High throughput discovery of ligand scaffolds for target proteins can accelerate development of leads and drug candidates enormously. Here we describe an innovative workflow for the discovery of high affinity ligands for the benzodiazepine-binding site on the so far not crystallized mammalian GABAA receptors. The procedure includes chemical biology techniques that may be generally applied to other proteins. Prerequisites are a ligand that can be chemically modified with cysteine-reactive groups, knowledge of amino acid residues contributing to the drug-binding pocket, and crystal structures either of proteins homologous to the target protein or, better, of the target itself. Part of the protocol is virtual screening that without additional rounds of optimization in many cases results only in low affinity ligands, even when a target protein has been crystallized. Here we show how the integration of functional data into structure-based screening dramatically improves the performance of the virtual screening. Thus, lead compounds with 14 different scaffolds were identified on the basis of an updated structural model of the diazepam-bound state of the GABAA receptor. Some of these compounds show considerable preference for the ?3?2?2 GABAA receptor subtype. PMID:24960548

Middendorp, Simon J; Puthenkalam, Roshan; Baur, Roland; Ernst, Margot; Sigel, Erwin

2014-08-15

50

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

51

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

52

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 713?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 1019?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

53

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

54

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

PubMed

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

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

2012-05-01

55

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

56

Scintillator materials for calorimetry  

SciTech Connect

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

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

1994-09-01

57

Scintillator manufacture at Fermilab  

SciTech Connect

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

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

1998-08-01

58

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

59

Multi-PSPMT scintillation camera  

SciTech Connect

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

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

1999-06-01

60

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

61

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

62

Scintillator and CMOS APS Imager for Radiography Conditions  

Microsoft Academic Search

We evaluated X-ray image performance for several scintillators and a CMOS APS imager by both diagnostic radiography and mammography conditions. Commercially available scintillators such as Lanex screen, needle structured CsI (Tl), and fiber optic structured CsI (Tl) were coupled with a CMOS APS imager. The X-ray machines used in this study were fixed tube voltage of 80 kVp and variable

Kwang Hyun Kim; Young Soo Kim

2008-01-01

63

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

E-print Network

the journey's launch at Lee's Ferry to the world-famous Lava Falls rapids, from the turquoise waters of Havasu O D U C T I O N #12;2 TEACHER'S GUIDE I am the lakes and the oceans. I am the clouds and the rain. I

Mathis, Wayne N.

64

What ethical and legal principles should guide the genotyping of children as part of a personalised screening programme for common cancer?  

PubMed

Increased knowledge of the gene-disease associations contributing to common cancer development raises the prospect of population stratification by genotype and other risk factors. Individual risk assessments could be used to target interventions such as screening, treatment and health education. Genotyping neonates, infants or young children as part of a systematic programme would improve coverage and uptake, and facilitate a screening package that maximises potential benefits and minimises harms including overdiagnosis. This paper explores the potential justifications and risks of genotyping children for genetic variants associated with common cancer development within a personalised screening programme. It identifies the ethical and legal principles that might guide population genotyping where the predictive value of the testing is modest and associated risks might arise in the future, and considers the standards required by population screening programme validity measures (such as the Wilson and Jungner criteria including cost-effectiveness and equitable access). These are distinguished from the normative principles underpinning predictive genetic testing of children for adult-onset diseases-namely, to make best-interests judgements and to preserve autonomy. While the case for population-based genotyping of neonates or young children has not yet been made, the justifications for this approach are likely to become increasingly compelling. A modified evaluative and normative framework should be developed, capturing elements from individualistic and population-based approaches. This should emphasise proper communication and genuine parental consent or informed choice, while recognising the challenges associated with making unsolicited approaches to an asymptomatic group. Such a framework would be strengthened by complementary empirical research. PMID:23454719

Hall, Alison Elizabeth; Chowdhury, Susmita; Pashayan, Nora; Hallowell, Nina; Pharoah, Paul; Burton, Hilary

2014-03-01

65

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

66

Recent developments in scintillator research  

SciTech Connect

Some results of recent scintillator research are presented. A description of the scintillation mechanisms of BaF/sub 2/, and of the influence of Pb/sup 2/ and La/sup 3/+ doping on the scintillation characteristics is given. Furthermore, the UV scintillation properties of LaF/sub 3/:Nd/sup 3/+ are discussed. Scintillation light (lambda=173 nm) emitted by this crystal can be detected in a photosensitive MWPC. The decay time of the emission is 6 ns.

Schotanus, P.; Dorenbos, P.; Von Eijk, C.W.E.; Hollander, R.W.

1989-02-01

67

Liquid scintillator sampling calorimetry  

E-print Network

LIQUID SCINTILLATOR SAMPLING CALORIMETRY A Thesis by R. GREG DUDGEON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1994 Major... Subject: Physics LIQUID SCINTILLATOR SAMPLING CALORIMETRY A Thesis by R. GREG DUDGEON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved...

Dudgeon, R. Greg

2012-06-07

68

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

69

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

PubMed

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

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

2014-11-01

70

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

71

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, Frdric; Beddar, A Sam; Beaulieu, Luc

2006-09-01

72

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

73

Liquid Scintillation Counting Technique  

Microsoft Academic Search

3 INCDIE ICPE- CA, 313 Splaiul Unirii, 030138, Bucharest, Romania The method applied to the evaluation of radiation activities implies sample preparation, liquid scintillation cocktail choosing, quench standard curve constructing and implementation, and results verification. We have constructed the quench curve using interpolation method by polynomial spline functions of three degree. In order to evaluate the measurement efficiencies of tritium

MAGDALENA DIANU; CORNELIU PODINA; TRAIAN ZAHARESCU

74

Scintillator Waveguide For Sensing Radiation  

DOEpatents

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

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

2003-04-22

75

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

76

Toxicology screen  

MedlinePLUS

... Analgesics - screen; Antidepressants - screen; Narcotics - screen; Phenothiazines - screen; Drug abuse screen; Blood alcohol test ... poisoning) Complicated alcohol abstinence (delirium tremens) Delirium ... Fetal alcohol syndrome Intentional overdose Seizures Stroke ...

77

Scintillation detectors based on silicon microfluidic channels  

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

78

Fabrication of fiber-optic radiation sensor tips with inorganic scintillator for remote sensing of X or ?-ray  

Microsoft Academic Search

In this study, fiber-optic radiation sensor tips are fabricated for remote sensing of X or ?-ray with inorganic scintillators and plastic optical fiber. The visible range of light from the inorganic scintillator that is generated by radiation source is guided by the plastic optical fiber and is measured by optical detector and power-meter. Two kinds of sensor tips are designed

B. S. Lee; Y. M. Hwang; H. S. Cho; S. Kim; S. Cho

2004-01-01

79

Scintillations of Laguerre Gaussian beams  

Microsoft Academic Search

By using the Rytov method, we formulate and numerically evaluate the scintillations of Laguerre Gaussian beams in weak atmospheric\\u000a turbulence. Our results indicate that at on-axis positions, Laguerre Gaussian beams with zero angular mode number will have\\u000a less scintillations than fundamental Gaussian beams, where the amount of scintillations will further decrease with rising\\u000a radial mode number. When off-axis positions are

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

2010-01-01

80

Investigation of radiation absorption and X-ray fluorescence properties of medical imaging scintillators by Monte Carlo methods  

NASA Astrophysics Data System (ADS)

X-ray absorption and X-ray fluorescence properties of medical imaging scintillating screens were studied by Monte Carlo methods as a function of the incident photon energy and screen-coating thickness. The scintillating materials examined were Gd 2O 2S, (GOS) Gd 2SiO 5 (GSO) YAlO 3 (YAP), Y 3Al 5O 12 (YAG), LuSiO 5 (LSO), LuAlO 3 (LuAP) and ZnS. Monoenergetic photon exposures were modeled in the range from 10 to 100 keV. The corresponding ranges of coating thicknesses of the investigated scintillating screens ranged up to 200 mg cm -2. Results indicated that X-ray absorption and X-ray fluorescence are affected by the incident photon energy and the screen's coating thickness. Regarding incident photon energy, this X-ray absorption and fluorescence was found to exhibit very intense changes near the corresponding K edge of the heaviest element in the screen's scintillating material. Regarding coating thickness, thicker screens exhibited higher X-ray absorption and X-ray fluorescence. Results also indicated that a significant fraction of the generated X-ray fluorescent quanta escape from the scintillating screen. This fraction was found to increase with screen's coating thickness. At the energy range studied, most of the incident photons were found to be absorbed via one-hit photoelectric effect. As a result, the reabsorption of scattered radiation was found to be of rather minor importance; nevertheless this was found to increase with the screen's coating thickness. Differences in X-ray absorption and X-ray fluorescence were found among the various scintillators studied. LSO scintillator was found to be the most attractive material for use in many X-ray imaging applications, exhibiting the best absorption properties in the largest part of the energy range studied. Y-based scintillators were also found to be of significant absorption performance within the low energy ranges.

Nikolopoulos, D.; Kandarakis, I.; Cavouras, D.; Valais, I.; Linardatos, D.; Michail, C.; David, S.; Gaitanis, A.; Nomicos, C.; Louizi, A.

2006-09-01

81

Liquid xenon scintillation spectrometer  

NASA Astrophysics Data System (ADS)

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

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

1987-02-01

82

Development of radiation hard scintillators  

SciTech Connect

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

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

1993-11-01

83

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

84

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

85

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

86

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

87

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.; Gorbea, D.; Ferrero, A.; De La Vega, G.; Lucero, A.; Suarez, F.; Videla, M.; Wainberg, O.; Etchegoyen, A.

2011-06-01

88

Encapsulated scintillation detector  

SciTech Connect

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

Toepke, I.L.

1983-05-10

89

Scintillation Light from Cosmic-Ray Muons in Liquid Argon  

E-print Network

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

Whittington, Denver

2014-01-01

90

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

91

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

92

An imaging technique for detection and absolute calibration of scintillation light  

SciTech Connect

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

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

2010-03-15

93

Combination of preparative HPLC and HSCCC methods to separate phosphodiesterase inhibitors from Eucommia ulmoides bark guided by ultrafiltration-based ligand screening.  

PubMed

Phosphodiesterase (PDE) inhibitors are widely used because of their various pharmacological properties, and natural products are considered the most productive source of PDE inhibitors. In this work, a new ultrafiltration-high-performance liquid chromatography (HPLC)-diode-array detection-mass spectrometry based ligand screening was developed for the first screening of PDE inhibitors from Eucommia ulmoides bark, and then the target bioactive compounds were prepared by combination of stepwise preparative HPLC and high-speed countercurrent chromatography (HSCCC) methods. Experiments were conducted to optimize the parameters in ultrafiltration, stepwise preparative HPLC, and HSCCC to allow rapid and effective screening and isolation of active compounds from complex mixtures. Seven lignans with purity over 97 % were isolated and identified by their UV, electrospray ionization mass spectrometry, and NMR data as (+)-pinoresinol-4,4'-di-O-?-D-glucopyranoside (1), (+)-pinoresinol-4-O-?-D-glucopyranosyl(1 ? 6)-?-D-glucopyranoside (2), (+)-medioresinol-4,4'-di-O-?-D-glucopyranoside (3), (+)-syringaresinol-4,4'-di-O- ?-D-glucopyranoside (4), (-)-olivil-4'-O-?-D-glucopyranoside (5), (-)-olivil-4-O-?-D- glucopyranoside (6), and (+)-pinoresinol-4-O-?-D-glucopyranoside (7). Compound 2 was first isolated from the genus Eucommia. Lignan diglucopyranosides (compounds 1-4) shower a greater inhibitory effect than lignan monoglucopyranosides (compounds 5-7). The method developed could be widely applied for high-throughput screening and preparative isolation of PDE inhibitors from natural products. PMID:23404133

Shi, Shu-Yun; Peng, Mi-Jun; Zhang, Yu-Ping; Peng, Sheng

2013-05-01

94

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

95

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

96

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

97

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

98

Characterization of liquid scintillation detectors  

NASA Astrophysics Data System (ADS)

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

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

2002-01-01

99

Scintillator Cosmic Ray Super Telescope  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

100

Composite scintillators for detection of ionizing radiation  

SciTech Connect

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

Dai, Sheng (Knoxville, TN) [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

101

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.; Bagn, H.; Tarancn, A.; Garcia, J. F.

2013-01-01

102

Potential image quality in scintillator-CCD-based x-ray imaging systems for digital radiography and digital mammography  

Microsoft Academic Search

The purpose of this work is to investigate the potential image quality of scintillator\\/CCD-based direct digital medical x-ray imaging systems. The x-ray detector is composed of a scintillating screen to convert x-ray photons into lower energy radiation (UV\\/visible\\/NIR) that is then collected by a lens or a fiberoptic taper and converted to an electrical signal by a CCD. The DQE

Shahram Hejazi; David P. Trauernicht

1996-01-01

103

SNO+ Scintillator Purification and Assay  

NASA Astrophysics Data System (ADS)

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

Ford, R.; Chen, M.; Chkvorets, O.; Hallman, D.; Vzquez-Juregui, E.

2011-04-01

104

An interplanetary scintillation activity index  

Microsoft Academic Search

Using interplanetary scintillation (IPS) data obtained from the Cambridge 81.5 MHz array, an activity index is developed in which it is possible to identify (1) discrete structures, most likely relating to transient density enhancements, and (2) periodic activity, relating to corotating interplanetary structure. Significant, yet weak correlations are found between the index and geomagnetic activity. Results suggest that the pursuit

R. A. Harrison; M. A. Hapgood; V. Moore; E. A. Lucek

1992-01-01

105

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

106

SNO+ Scintillator Purification and Assay  

SciTech Connect

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

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

2011-04-27

107

Method of making a scintillator waveguide  

DOEpatents

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

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

2000-01-01

108

Cosmic ray scintillations. II - General theory of interplanetary scintillations  

NASA Technical Reports Server (NTRS)

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

Owens, A. J.

1974-01-01

109

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

110

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

111

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

PubMed

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

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

2013-01-01

112

Pixel-structured scintillators for digital x-ray imaging  

NASA Astrophysics Data System (ADS)

We exploit the development of a pixel-structured scintillator that would match the readout pixel array, such as a photodiode array. This combination may become an indirect-conversion detector having high x-ray sensitivity without sacrificing the inherent resolving power defined by the pixel geometry of the photodiodes, because the scintillation material has a relatively high atomic number and density compared with the photoconductors, and the pixel-structured design may provide a band-limited modulation-transfer function (MTF) characteristic even with a thicker scintillator. For the realization of pixel-structured scintillators, two-dimensional (2D) array of pixel-structured wells with a depth of 100?m was prepared by using a deep reactive ion etching (DRIE) process on a silicon wafer. Then, Gd2O2S:Tb phosphor powders with organic binders were filled within the well array by using a sedimentation method. Three different pixel designs of 50, 100 and 200 ?m with a wall (or septum) thickness of 10 ?m were considered. Each sample size was 20 30 mm2 considering intra-oral imaging. The samples were coupled to the CMOS photodiode array with a pixel pitch of 48 ?m and the imaging performances were evaluated in terms of MTF, NPS (noise-power spectrum) and DQE (detective quantum efficiency) at intra-oral imaging conditions. From the measurement results, the sensitivities of the samples with 50, 100 and 200 ?m pitch designs were about 12, 25 and 41% of that of the reference commercial phosphor screen (MinR-2000). Hence the DQE performances at 0.2 lp/mm were about 3.7, 9.6, 22.7% of the reference screen. According to the Monte Carlo simulations, the lower sensitivity was due to the loss of optical photons in silicon walls. However, the MTF performance was mainly determined by the designed pixel apertures. If we make pixel-structured scintillators with a deeper depth and provide reflectance on walls, much enhanced DQE performance is expected.

Yun, Seung Man; Lim, Chang Hwy; Kim, Tae Woo; Kim, Ho Kyung

2009-02-01

113

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

114

Detecting scintillations in liquid helium  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

115

The Virtual Desktop User's Guide  

E-print Network

The Virtual Desktop User's Guide Version 1.0 · 18 April, 2000 #12;Table of contents 1. Registration.......................................................................................................... 16 The Virtual Desktop · User's Guide Page 1 #12;1. Registration If you are a new user, this is your at the Virtual Desktop system for the first time, you will be presented with the screen in Figure 1 (the main

Riabov, Vladimir V.

116

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

117

Imaging-based screening: understanding the controversies.  

PubMed

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

2014-11-01

118

Coorelation between VHF scintillation and spread F  

NASA Astrophysics Data System (ADS)

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

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

2003-04-01

119

Low-cost extruded plastic scintillator  

NASA Astrophysics Data System (ADS)

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

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

2001-07-01

120

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

121

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

122

OVERCOMING IONOSPHERIC SCINTILLATION FOR WORLDWIDE GPS AVIATION  

E-print Network

in the equatorial area, including Brazil and India, is ionospheric scintillation. Due to electron density irregularities inside the ionosphere, transionospheric radio waves interfere constructively and de- structively

Stanford University

123

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

124

Modernized GPS Signals and Ionospheric Scintillation  

NASA Astrophysics Data System (ADS)

One of the major threats to accurate and reliable navigation, positioning, and timing (PNT) using the L1 CA code is scintillation produced by ionospheric irregularities. The introduction of new civilian PRN codes on L2 and L5 promise more accurate and reliable PNT, but these new signals are also vulnerable to scintillation. Recently we have developed GPS software receivers for examining the details of amplitude and phase scintillations on L1 and L2. These software receivers demonstrate that on L1, amplitude and phase scintillations are not independent and are strongly correlated. That is, the fastest phase shifts occur during the deepest fades. This leads to a similar question, are scintillations independent on L1 and L2? An experiment to address this question was conducted in January 2007. Signals were collected from the L1CA code and the L2C code during moderate scintillations using a software receiver located at Natal, Brazil. The answer to the question is that scintillations are strongly correlated between L1 and L2 for this example. The consequence of this strong correlation is that tracking will be unable to switch between the L1 and L2 signals when one of the signals is challenged by a fade for at least moderate scintillation levels. Earlier experiments at L band frequencies suggest that during strong scintillation fading may be less well correlated between L1 and L2. We present simulations to examine this hypothesis.

Kintner, P. M.; Cerruti, A.; O'Hanlon, B.; Humphreys, T.; Psiaki, M.

2008-12-01

125

SPA Non-Exempt Time Capture Employees TIM Reference Guide  

E-print Network

-Exempt Time Capture Reference Guide Page 5 Record a Time Stamp 1. The Time Stamp screen appears when a SPA Non to record a time in or out. 2. The Time Stamp Results screen appears with the recorded time. #12;SPA Non-Exempt Time Capture Reference Guide Page 6 Open My Timecard 1. The Time Stamp screen appears when a SPA Non

Crews, Stephen

126

Health Screening  

MedlinePLUS

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

127

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

PubMed Central

Background Large-scale annotation efforts have improved our ability to coarsely predict regulatory elements throughout vertebrate genomes. However, it is unclear how complex spatiotemporal patterns of gene expression driven by these elements emerge from the activity of short, transcription factor binding sequences. Results We describe a comprehensive promoter extension assay in which the regulatory potential of all 6 base-pair (bp) sequences was tested in the context of a minimal promoter. To enable this large-scale screen, we developed algorithms that use a reverse-complement aware decomposition of the de Bruijn graph to design a library of DNA oligomers incorporating every 6-bp sequence exactly once. Our library multiplexes all 4,096 unique 6-mers into 184 double-stranded 15-bp oligomers, which is sufficiently compact for in vivo testing. We injected each multiplexed construct into zebrafish embryos and scored GFP expression in 15 tissues at two developmental time points. Twenty-seven constructs produced consistent expression patterns, with the majority doing so in only one tissue. Functional sequences are enriched near biologically relevant genes, match motifs for developmental transcription factors, and are required for enhancer activity. By concatenating tissue-specific functional sequences, we generated completely synthetic enhancers for the notochord, epidermis, spinal cord, forebrain and otic lateral line, and show that short regulatory sequences do not always function modularly. Conclusions This work introduces a unique in vivo catalog of short, functional regulatory sequences and demonstrates several important principles of regulatory element organization. Furthermore, we provide resources for designing compact, reverse-complement aware k-mer libraries. PMID:23867016

2013-01-01

128

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.

129

Scintillation properties of lead sulfate  

SciTech Connect

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

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

1991-11-01

130

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

SciTech Connect

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

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

1996-06-01

131

On the Relation between Auroral ``Scintillation'' and ``Phase Without Amplitude'' Scintillation: Initial Investigations  

NASA Astrophysics Data System (ADS)

The ionosphere, being a plasma, affects any radio signal passing through it by introducing a phase advance and a group delay in the signal. Occasionally, due to electron density irregularities in the ionosphere, the radio signal can experience rapid amplitude and phase fluctuations called scintillation. Scintillation can sometimes be intense enough to cause a Global Positioning System (GPS) receiver to lose lock on a signal, thus making it a significant aspect to consider in GPS-based positioning, navigation, and timing systems. Quantitative information about scintillation is usually obtained from parameters called the scintillation indices. The most commonly used GPS scintillation indices are S _{4} and sigma{phi} that quantify scintillation in power and phase of the GPS signal, respectively. Recent studies have shown that at high latitudes, the probability of occurrence of phase scintillation is greater than amplitude scintillation. These events are called phase without amplitude scintillation. In this study, the relation between these events and auroral scintillation is analyzed. As an initial step, data from the Canadian High Arctic Ionospheric Network and 10 more GPS stations located in Canada was used simultaneously along with data from 11 Canadian THEMIS all-sky imagers. Preliminary investigations reveal that phase fluctuations associated with aurora can be the main reason behind phase without amplitude scintillation. Spectral studies of differential-carrier-phase TEC were also performed.

Mushini, Sajan; Spanswick, Emma; Jayachandran, Thayyil; Donovan, Eric; Langley, R.; Prikryl, Paul

132

Binderless composite scintillator for neutron detection  

DOEpatents

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

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

2009-03-10

133

Scintillation is an indicator of astrometric stability  

NASA Astrophysics Data System (ADS)

We examine the relationship between astrometric stability and astrophysical properties in flat-spectrum radio-loud quasars making up the celestial reference frame. We use position determinations from geodetic very long baseline interferometry measurements and develop a new metric for source position stability. We then compare this quantity to two measures of source compactness: structure index, which probes structure on milliarcsecond scales and the presence of interstellar scintillation associated with the quasar, which probes scales of tens of ?as. We find that persistent scintillators have greater position stability than episodic scintillators, which are in turn more stable than non-scintillators. Scintillators are also more likely to be compact on milliarcsecond scales, as measured by the structure index. Persistent scintillators are therefore excellent candidates for inclusion in any future realization of the celestial reference frame. A list of these sources is presented in Appendix A. We find that slow (characteristic time-scale >3 d) scintillators have more stable positions than rapid scintillators, suggesting that they are more compact. High-cadence, long-term monitoring is therefore required to identify other members of this population of compact, high brightness temperature quasars.

Schaap, R. G.; Shabala, S. S.; Ellingsen, S. P.; Titov, O. A.; Lovell, J. E. J.

2013-09-01

134

Wind effects on scintillation decorrelation times  

Microsoft Academic Search

The effects of wind on scintillation decorrelation times are well known only for winds transverse to the propagation path. Therefore, we have investigated such effects using laser scintillation and sonic anemometer data obtained at an outdoor test site at DRDC-Valcartier. The data were taken during both day and night periods in May and June 2003. Meteorological data were also taken

Guy Potvin; Denis Dion Jr.; J. L. Forand

2005-01-01

135

Luminescence and Scintillation Properties at the Nanoscale  

Microsoft Academic Search

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

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

2010-01-01

136

The most powerful scintillator supernovae detector: LVD  

Microsoft Academic Search

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

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

1992-01-01

137

Extruded scintillator for the Calorimetry applications  

SciTech Connect

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

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

2006-10-27

138

Genetic Screening  

PubMed Central

Current approaches to genetic screening include newborn screening to identify infants who would benefit from early treatment, reproductive genetic screening to assist reproductive decision making, and family history assessment to identify individuals who would benefit from additional prevention measures. Although the traditional goal of screening is to identify early disease or risk in order to implement preventive therapy, genetic screening has always included an atypical elementinformation relevant to reproductive decisions. New technologies offer increasingly comprehensive identification of genetic conditions and susceptibilities. Tests based on these technologies are generating a different approach to screening that seeks to inform individuals about all of their genetic traits and susceptibilities for purposes that incorporate rapid diagnosis, family planning, and expediting of research, as well as the traditional screening goal of improving prevention. Use of these tests in population screening will increase the challenges already encountered in genetic screening programs, including false-positive and ambiguous test results, overdiagnosis, and incidental findings. Whether this approach is desirable requires further empiric research, but it also requires careful deliberation on the part of all concerned, including genomic researchers, clinicians, public health officials, health care payers, and especially those who will be the recipients of this novel screening approach. PMID:21709145

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

2011-01-01

139

Scintillation proximity assay using polymeric membranes  

SciTech Connect

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

Mansfield, R.K.

1992-01-01

140

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

Microsoft Academic Search

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

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

2011-01-01

141

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

NASA Astrophysics Data System (ADS)

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

Roux, Filippus S.

2014-05-01

142

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

143

Cerium oxidation state in LSO:Ce scintillators  

Microsoft Academic Search

Trivalent cerium ions form the luminescence centers in several important families of scintillation materials including the rare earth oxyorthosilicates, pyrosilicates, and aluminates. When comparing the experimentally determined scintillation properties of cerium-doped scintillators to theoretical models of scintillation mechanisms, there is often speculation regarding the fraction of the total cerium that exists in the radiative trivalent charge state (Ce3+) rather than

Charles L. Melcher; Stephan Friedrich; Stephen P. Cramer; Merry A. Spurrier; Piotr Szupryczynski; Ron Nutt

2005-01-01

144

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

145

Some results of night-time scintillations at low latitude  

NASA Astrophysics Data System (ADS)

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

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

1993-06-01

146

The Borexino scintillator and solvent procurement  

NASA Astrophysics Data System (ADS)

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

Giammarchi, Marco

2014-05-01

147

Scintillation of rare earth doped fluoride nanoparticles  

SciTech Connect

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

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

2011-09-12

148

Genetic Screening  

NSDL National Science Digital Library

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

Slesnick, Irwin

2004-01-01

149

Screen Time  

NSDL National Science Digital Library

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

Omsi

2007-01-01

150

New observations of scintillation climatology from the Scintillation Network Decision Aid (SCINDA)  

NASA Astrophysics Data System (ADS)

The Scintillation Network Decision Aid (SCINDA) was established with three ground sites in the mid-1990's by the Air Force Research Laboratory and has continued to grow into a global scintillation observation network. This system consists of an array of VHF and GPS receivers which continually measure scintillation in the equatorial region. In the past few years, the extended network of ground stations has expanded into the African sector. Initial results from yearly scintillation data obtained from two VHF receivers in Narobi, Kenya and Bahir Dar, Ethiopia in 2011 indicate the presence of scintillation activity throughout the June-July -August (northern summer) season which is inconsistent with current state-of-the-art ionospheric climatology models. It is well known that seasonal equatorial scintillation patterns vary with longitude based on geographical location. For example, the scintillation activity at VHF frequencies are absent in the Pacific sector during the months of November to February while observations from South America show nearly continuous scintillation during this same time period. With little to no ground-based observations, the scintillation climatology over the African region has not been well understood. In the paper, we will present S4 measurements various longitudinal sectors, including the first look at solar maximum type conditions over the African sector, and provide comparisons with output from a global climatology model.

Su, Y.; Caton, R. G.; Wiens, K.; Groves, K. M.

2012-12-01

151

Colon cancer screening  

MedlinePLUS

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

152

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

153

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

NASA Astrophysics Data System (ADS)

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

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

2008-09-01

154

Inorganic scintillators in direct dark matter investigation  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

155

Liquid scintillators for optical fiber applications  

DOEpatents

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

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

1982-01-01

156

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

157

Scintillation properties of YAP:Ce  

Microsoft Academic Search

Yttrium aluminium perovskite activated by cerium (formula YAlO3:Ce, abbreviated YAP:Ce) is systematically investigated in view of its use as efficient scintillator for various applications. The basic physical and chemical properties of YAP:Ce monocrystals are summarized in this paper. The luminescence, scintillation and absorption characteristics, the ?-ray detection capability, energy resolution in the range of 30600 keV, light yield and radiation

S. Baccaro; F de Notaristefani; P Maly; J. A Mares; R. Pani; R. Pellegrini; A. Soluri

1995-01-01

158

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

159

Sepsis screening.  

PubMed

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

2014-10-30

160

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

161

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.

162

Hypertension screening  

NASA Technical Reports Server (NTRS)

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

Foulke, J. M.

1975-01-01

163

TORCH screen  

MedlinePLUS

... a newborn. TORCH stands for toxoplasmosis , rubella , cytomegalovirus, herpes simplex, and HIV, but it can also include other ... screen infants for infections such as toxoplasmosis, cytomegalovirus, herpes simplex, syphilis and others. These infections may lead to ...

164

Vision Screening  

MedlinePLUS

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

165

Ripcorder Screen  

NSDL National Science Digital Library

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

2012-11-06

166

Preparation of paper scintillator for detecting 3H contaminant.  

PubMed

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

Miyoshi, Hirokazu; Ikeda, Toshiji

2013-09-01

167

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

E-print Network

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

168

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

NASA Astrophysics Data System (ADS)

Detecting the scintillation light coming from a thin sheet of plastic scintillator (PS) provides a promising fast and precise tissue equivalent method for radiation dose measurements in two dimensions. The successful implementation of such technique requires high efficiency, dosimetric tissue equivalence and high localization of the scintillation process. The last is needed to assure that the light photons originating from a pixel of the scintillator sheet correspond to energy deposited in the same pixel. Since no such information is available for PS material with standard or modified chemical composition we have developed two experimental methods for assessing the scintillation locality by measuring the optical spectra and the scintillation light profile (SLP) of PS samples with different thickness. The results of the two types of measurements are consistent with each other and with a simple theoretical model of the energy conversion process. We have demonstrated that comparing the relative intensities of the primary and secondary photon peaks in the optical spectra of the scintillator is a sensitive approach to determine the delocalization of the secondary photon emission. The ratio of the number of primary to secondary photons shows strong dependence on PS dye composition. Two types of plastic scintillator materials were tested and the advantages of one of them for radiation dosimetry are demonstrated.

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

2000-01-01

169

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.

170

Screening for cancer  

SciTech Connect

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

Miller, A.B.

1985-01-01

171

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

172

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

PubMed

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. PMID:18777928

Lacroix, Frderic; Archambault, Louis; Gingras, Luc; Guillot, Mathieu; Beddar, A Sam; Beaulieu, Luc

2008-08-01

173

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

174

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

175

Photovoltaic nanocrystal scintillators hybridized on Si solar cells  

E-print Network

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

Demir, Hilmi Volkan

176

Development of nanocomposite scintillators R. E. Del Sesto  

E-print Network

ew scintillator materials are in high demand to assist in non-proliferation and counter-proliferation- tion of nuclear materials. In order to create a new class of scintillator materials that combines good

177

Analysis of atmospheric effects on stellar scintillation  

NASA Astrophysics Data System (ADS)

Atmospheric effects on normalized stellar irradiance fluctuations for the weak fluctuation regime are examined. Both monochromatic and polychromatic effects are considered. Calculations are performed using a Rytov theory which explicitly includes refractive effects arising from the polychromatic stellar source. The atmospheric turbulence along the path is specified in a spherical shell or `onion- skin' model using a vertical profile specified by either the Clear 1 model or actual thermosonde measurements. Finite optical bandwidth, receiver aperture size, and variable turbulent inner scale are also included. Good agreement is found between ground-based measurements and model results in the weak scintillation regime. It is also shown that refraction effects can significantly alter the wavelength dependence of scintillation as well as produce a leveling off and decrease of scintillation with increasing zenith angle that could be misinterpreted as saturation.

Beland, Robert R.; Roadcap, John R.

2000-07-01

178

Current trends in scintillator detectors and materials  

SciTech Connect

The last decade has seen a renaissance in inorganic scintillator development for gamma ray detection. Lead tungstate (PbWO4) has been developed for high energy physics experiments, and possesses exceptionally high density and radiation hardness, albeit with low luminous efficiency. Lutetium orthosilicate or LSO (Lu2SiO5:Ce) possesses a unique combination of high luminous efficiency, high density, and reasonably short decay time, and is now incorporated in commercial positron emission tomography (PET) cameras. There have been advances in understanding the fundamental mechanisms that limit energy resolution, and several recently discovered materials (such as LaBr3:Ce) possess energy resolution that approaches that of direct solid state detectors. Finally, there are indications that a neglected class of scintillator materials that exhibit near band-edge fluorescence could provide scintillators with sub-nanosecond decay times and high luminescent efficiency.

Moses, William W.

2001-10-23

179

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

180

Hearing Screening  

ERIC Educational Resources Information Center

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

Johnson-Curiskis, Nanette

2012-01-01

181

SCREENING TECHNOLOGIES  

EPA Science Inventory

Field screening methods are used to determine whether a characteristic of interest is present or absent, above and below a predetermined threshold at a given site, or in a concentration within a predetermined range of interest. or the U.S. EPA and the regulated community much emp...

182

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

PubMed Central

The use of thick segmented scintillators in electronic portal imagers offers the potential for significant improvement in x-ray detection efficiency compared to conventional phosphor screens. Such improvement substantially increases the detective quantum efficiency (DQE), leading to the possibility of achieving soft-tissue visualization at clinically-practical (i.e. low) doses using megavoltage (MV) cone-beam computed tomography. While these DQE increases are greatest at zero spatial frequency, they are diminished at higher frequencies as a result of degradation of spatial resolution due to lateral spreading of secondary radiation within the scintillator an effect that is more pronounced for thicker scintillators. The extent of this spreading is even more accentuated for radiation impinging the scintillator at oblique angles of incidence due to beam divergence. In this paper, Monte Carlo simulations of radiation transport, performed to investigate and quantify the effects of beam divergence on the imaging performance of MV imagers based on two promising scintillators (BGO and CsI:T1), are reported. In these studies, 10 40 mm thick scintillators, incorporating low-density polymer, or high-density tungsten septal walls were examined for incident angles corresponding to that encountered at locations up to ~15 cm from the central beam axis (for an imager located 130 cm from a radiotherapy x-ray source). The simulations demonstrate progressively more severe spatial resolution degradation (quantified in terms of the effect on modulation transfer function) as a function of increasing angle of incidence (as well as of scintillator thickness). Since the noise power behavior was found to be largely independent of incident angle, the dependence of the DQE on incident angle is therefore primarily determined by the spatial resolution. The observed DQE degradation suggests that 10 mm thick scintillators are not strongly affected by beam divergence for detector areas up to ~30 30 cm2. For thicker scintillators, the area that is relatively unaffected is significantly reduced, requiring a focused scintillator geometry in order to preserve spatial resolution, and thus DQE. PMID:20526032

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

2010-01-01

183

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

SciTech Connect

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

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

1995-04-01

184

Neutrino tracking calorimetry with plastic scintillator bars  

NASA Astrophysics Data System (ADS)

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

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

2001-10-01

185

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

186

New liquid scintillators for fiber-optic applications  

SciTech Connect

New long-wavelength-emitting, high-speed, liquid scintillators have been developed and tailored specifically for plasma diagnostic experiments employing fiber optics. These scintillators offer significant advantages over commercially available plastic scintillators in terms of sensitivity and bandwidth. FWHM response times as fast as 350 ps have been measured. Emission spectra, time response data, and relative sensitivity information are presented.

Lutz, S.S.; Franks, L.A.; Flournoy, J.M.; Lyons, P.B.

1981-01-01

187

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

188

Development and use of a GPS ionospheric scintillation monitor  

Microsoft Academic Search

Global Positioning System (GPS) satellite signals provide convenient radio beacons for ionospheric studies. Among other propagation phenomena, the ionosphere affects GPS signal propagation through amplitude scintillations that develop after radio waves propagate through ionospheric electron density irregularities. This paper outlines the design, testing, and operation of a specialized GPS receiver to monitor L-band amplitude scintillations: the Cornell scintillation monitor. The

Theodore L. Beach; Paul M. Kintner

2001-01-01

189

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

Microsoft Academic Search

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

J. A. Sanchez-Cabeza; Ll. Pujol

1995-01-01

190

Bird Guide  

NSDL National Science Digital Library

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

Houston, Children'S M.

2011-01-01

191

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

SciTech Connect

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

Nodulman, L.

1989-01-01

192

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 (7.96S, 14.41W) 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

193

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

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

2013-01-01

194

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

195

IMPROVED RESULTS USING HIGHER RATIOS OF SCINTILLATOR SOLUTION TO BENZENE IN LIQUID SCINTILLATION SPECTROMETRY  

Microsoft Academic Search

Practical effects of the volumetric or weight ratio of scintillator solution to sample benzene in liquid scintilla- tion spectrometry were examined here for radiocarbon dating. It is concluded, using a LKB-Wallac Quantulus 1220 and Teflon -copper 3 mL vials with scintillator of toluene-based PPO and POPOP, that solutions containing the same concen- trations of the same ratio, 1.3 or more,

Motoharu Koba

196

The homestake surface-underground scintillations: Description  

Microsoft Academic Search

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

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

1985-01-01

197

Scintillation Materials Research Center Annual Report  

E-print Network

their experience with luminescence and thin film combinatorial techniques to build libraries of new scintillation Synthesis 7 Characterization 9 Personnel Staff 13 Students 13 Collaborators 13 Laboratory relocation 19 office: 301 Science and Engineering Research Facility (SERF) Characterization Lab: 302 SERF Synthesis Lab

Tennessee, University of

198

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

199

Wind effects on scintillation decorrelation times  

NASA Astrophysics Data System (ADS)

The effects of wind on scintillation decorrelation times are well known only for winds transverse to the propagation path. Therefore, we have investigated such effects using laser scintillation and sonic anemometer data obtained at an outdoor test site at DRDC-Valcartier. The data were taken during both day and night periods in May and June 2003. Meteorological data were also taken over these periods. Scintillation decorrelation times were then compared with the times deduced using the sonic anemometer wind data and Clifford's theory, which only uses the wind component transverse to the propagation path of the laser. Substantial differences were observed, because Clifford's theory does not take into account the effects of the wind's longitudinal component. A simple theoretical model has been developed to include the longitudinal wind. The model includes a free parameter that must be fitted to the data. Once this is done, the model allows us to predict, with reasonable accuracy, the scintillation decorrelation time scale given the inner scale and the wind at any angle. Residual discrepancies may be due to the internal evolution of the turbulence, which has not been included in our model and causes a decorrelation independent of the wind.

Potvin, Guy; Dion, Denis, Jr.; Forand, J. L.

2005-01-01

200

Scintillator Replacement Option for BaBar  

SciTech Connect

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

Lometti, m

2004-02-05

201

Light transport in long, plastic scintillators  

NASA Astrophysics Data System (ADS)

As a form of the input into the collaboration the group from the Andrzej So?tan Institute for Nuclear Studies undertook a task of investigating the validity of the design of a compact detector for Gamma Ray Bursts photon polarization measurements, known as POLAR. The authors focused at the scintillation and light transport properties of (20066) mm3 BC400 plastic bars as well as of other samples of BC408 plastic in the attempt to determine whether the assembled instrument is going to achieve the performance criteria bestowed upon it by the project. The investigation revealed a strong dependence between the amplitude of a signal and distance between the precursor interaction in a scintillator and the photodetector. Accordingly to this finding an attempt has been made to determine the influence of the surface polishing quality on the overall scintillator performance. The authors consider that proper machining of scintillator pieces, adequate choice of their packaging, and proper software analysis may overcome the revealed disadvantages.

Gierlik, M.; Batsch, T.; Marcinkowski, R.; Moszy?ski, M.; Sworobowicz, T.

2008-08-01

202

Temperature dependence of BCF plastic scintillation detectors.  

PubMed

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

Wootton, Landon; Beddar, Sam

2013-05-01

203

Temperature dependence of BCF plastic scintillation detectors  

NASA Astrophysics Data System (ADS)

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

Wootton, Landon; Beddar, Sam

2013-05-01

204

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 22C. 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

205

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

206

Quality control of liquid scintillation counters  

Microsoft Academic Search

Liquid scintillation counting (LSC) is widely used at LNHB for primary standardization of radionuclides (TDCR method), for secondary calibration and also for source stability studies or radioactive purity measurements. A total of five LSC counters are used for these purposes: two locally developed 3-photodetector counters for the implementation of the TDCR method, two Wallac 1414 counters and one Wallac 1220

F. Jaubert; I. Tarts; P. Cassette

2006-01-01

207

Performance of Water-based Liquid Scintillator  

NASA Astrophysics Data System (ADS)

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

Beznosko, Dmitriy

2013-04-01

208

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

Microsoft Academic Search

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

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

2003-01-01

209

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

Microsoft Academic Search

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

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

2003-01-01

210

RADTRAN 5 user guide.  

SciTech Connect

This User Guide for the RADTRAN 5 computer code for transportation risk analysis describes basic risk concepts and provides the user with step-by-step directions for creating input files by means of either the RADDOG input file generator software or a text editor. It also contains information on how to interpret RADTRAN 5 output, how to obtain and use several types of important input data, and how to select appropriate analysis methods. Appendices include a glossary of terms, a listing of error messages, data-plotting information, images of RADDOG screens, and a table of all data in the internal radionuclide library.

Kanipe, Frances L.; Neuhauser, Karen Sieglinde

2003-07-01

211

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 ...

212

discussion guide 2 discussion guide  

E-print Network

discussion guide #12;2 discussion guide AcKnoWLedgeMenTs Reconciling Injustices in a Pluralistic in part through funding from Citizenship and Immigration Canada. About Simon Fraser University's Centre to explore critical issues that impact the social, economic, environmental, and cultural well-being of our

213

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

214

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

215

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

216

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

217

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

218

Plastic fiber scintillator response to fast neutronsa)  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

219

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

220

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

221

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

222

Reflectance of polytetrafluoroethylene for xenon scintillation light  

SciTech Connect

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

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

2010-03-15

223

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 and ionization yields for nuclear recoils with energies from 10.3 to 57.2 keV and for applied electric fields from 0 to 1000 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. A comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field yielded a first evidence of sensitivity to direct...

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

2014-01-01

224

Investigation of radiation absorption and X-ray fluorescence properties of medical imaging scintillators by Monte Carlo methods D. Nikolopoulosa, I. Kandarakisa,, D. Cavourasa, I. Valaisa, D. Linardatosa, C. Michaila  

Microsoft Academic Search

X-ray absorption and X-ray fluorescence properties of medical imaging scintillating screens were studied by Monte Carlo methods as a function of the incident photon energy and screen-coating thickness. The scintillating materials examined were Gd2O2S, (GOS) Gd2SiO5 (GSO) YAlO3 (YAP), Y3Al5O12 (YAG), LuSiO5 (LSO), LuAlO3 (LuAP) and ZnS. Monoenergetic photon exposures were modeled in the range from 10 to 100 keV.

Agiou Spiridonos

225

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

226

A SCINTILLATION NUCLEAR INCIDENT ALARM MONITOR  

Microsoft Academic Search

The design of a scintillation nuclear incident alarming gamma field ; intensity from one mr\\/hr to greater than ten r\\/hr is described. Aa inexpensive ; high-voltage supply, an inexpensive terphenyl-in-Wlyvinyltoluene crystal, a ; multiplier phototube, and a meter relay are the basic components. An addenda two-; transistor booster amplifler can be used if necessary for very low-level ; triggering. The

1959-01-01

227

Thin GSO scintillator for neutron detection  

Microsoft Academic Search

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

P REEDER

1994-01-01

228

Properties of the YAG:Ce scintillator  

Microsoft Academic Search

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

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

1994-01-01

229

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

230

Liquid scintillator calorimetry for the LHC  

NASA Astrophysics Data System (ADS)

We report on the beam tests of full scale liquid scintillator modules designed for a very forward calorimeter for an experiment at the CERN Large Hadron Collider (LHC). Tests were performed in the electron beams of the SPS at CERN within the 20 and 150 GeV energy range. The response as a function of the beam impact point and incidence angle was measured.

Artamonov, A.; Buontempo, S.; Epstein, V.; Ereditato, A.; Fiorillo, G.; Garufi, F.; Golovkin, S.; Gorbunov, P.; Jemanov, V.; Khovansky, V.; Kruchinin, S.; Maslennikov, A.; Medvedkov, A.; Vasilchenko, V.; Zaitsev, V.; Zuckerman, I.

1995-02-01

231

Dark Matter Search with Direction Sensitive Scintillators  

E-print Network

We have carried out the dark matter search with a 116g direction-sensitive stilbene crystal in Kamioka Observatory. With the crystal fixed to the earth, we searched the modulation of thelight output. No modulation signal was found due to the small size of the detector crystal and the higher background rate yet to be eliminated. However, it demonstrated the effectiveness of the method of direction sensitive search for the dark matter with an implementation of the anisotropic organic scintillation crystal.

H. Sekiya; M. Mionwa; Y. Shimizu; W. Suganuma; Y. Inoue

2004-11-09

232

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

233

Beta spectra deconvolution for liquid scintillation counting  

Microsoft Academic Search

This study presents the first results of a deconvolution method for Liquid Scintillation complex spectra. The method has been\\u000a developed by means of the software MATLAB and is based on the utilization of Fourier Transforms. Its main target is to obtain\\u000a a fast calculation procedure capable to unfold complex spectra without requiring any preliminary knowledge of the peak shapes\\u000a of

Romolo Remetti; Alessandro Sessa

2011-01-01

234

Radiocarbon measurements by liquid scintillation spectrometry  

Microsoft Academic Search

Radiocarbon measurements by ultra low background scintillation spectrometer have been performed at the underground laboratory of Gran Sasso and radiocarbon laboratory of E.N.E.A.-Bologna to study the efficiency and background variations related to measurement sites. The data indicates a background reduction of approximtely 65% at the under- ground laboratory compared to surface one, with no differences in the efficiency. The cosmic

F. Bella; P. Bartolomei

235

a Subminiature Scintillation Detector for Catheter Operation  

NASA Astrophysics Data System (ADS)

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

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

2006-04-01

236

Making Movies: From Script to Screen.  

ERIC Educational Resources Information Center

This book is a guide to the making of films. It covers preparation (scripting, storyboarding, budgeting, casting, and crew selection), filming (directing, camera operating, and sound recording), and postproduction (editing, sound dubbing, laboratory processing, and trial screening). Distribution of films is discussed in detail. Possible careers in

Bobker, Lee R.

237

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

238

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

PubMed

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

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

2006-01-01

239

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 mm 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

240

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

241

Liquid-scintillation alpha-detection techniques  

SciTech Connect

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

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

1983-01-01

242

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

243

Scintillation-Induced Intermittency in SETI  

E-print Network

We consider interstellar scintillations as a cause of intermittency in radio signals from extraterrestrial intelligence (ETI). We demonstrate that scintillations are very likely to allow initial detections of narrowband signals from distant sources (> 100 pc), while making redetections improbable. We consider three models in order to assess the non-repeating, narrowband events found in recent SETI and to analyze large surveys in general: (I) Radiometer noise; (II) A population of constant Galactic sources undergoing interstellar scintillation,; and (III) Real, transient signals (or hardware errors) of either terrestrial or ET origin. We apply likelihood and Bayesian tests of the models to The Planetary Society/Harvard META data. We find that Models II and III are both highly preferred to Model I, but that Models II and III are about equally likely. Ruling out Model II in favor of Model III requires many more reobservations than were conducted in META *or* the reobservation threshold must be much lower than was used in META. *We cannot rule out the possibility that META events are real, intrinsically steady ETI signals.* We recommend that future surveys use thresholds far below the typical false-alarm threshold to lessen the effects of intermittency. The threshold level is best defined in terms of the recording and computational technology that is available at a cost commensurate with other survey costs.

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

1997-07-02

244

Multiple phase-screen simulation of oceanic beam propagation  

NASA Astrophysics Data System (ADS)

Oceanic turbulence is simulated with the help of a series of 2D phase-screens and used to investigate beam propagation in the ocean. Individual phase screens are created from a model for the spatial power spectrum of oceanic turbulence that includes both temperature and salinity fluctuations. Numerical simulation is compared with the experiment and with previous results in the literature. Intensity profiles as well as scintillation data is explored for several different turbulence parameters as well as for several propagation distances to examine a wide range of naturally occurring situations.

Farwell, Nathan H.; Korotkova, Olga

2014-10-01

245

Probing the gamma-scintillation process in semiconductor nanomaterials using ultrafast transient cathodoluminescence  

NASA Astrophysics Data System (ADS)

Energy-resolving gamma-ray detectors are of particular interest for the detection of illicit radioactive materials at border crossings and other portals because they offer fast, contactless screening that can discriminate between dangerous and benign materials. Among detector classes, scintillators offer an intriguing balance between cost and performance, but current technologies rely on single-crystal materials that are not scalable to portal-relevant detector sizes. Thus, there is a recognized need for novel, processible, high-performance scintillating materials or composites. Composites based on semiconductor nanocrystal quantum dots (QDs) are of interest because of their potentially high gamma-stopping power, high emission quantum yields, and low-cost solution synthesis and processing. Yet the performance of these and other granular nanomaterials has not met expectations. We suggest that this is due to the general lack of insight into the gamma-to-photons transduction process within these inherently more complex materials, which reduces the development and refinement of candidates to simple trial-and-error. Here, we describe the development of ultrafast transient cathodoluminescence as a unique spectroscopic tool for probing the population of excited states formed within a material during scintillation, and thus determining the major sources of energy loss. Our analysis shows that in the case of CdSe/ZnS core/shell QDs, any efficiency loss due to previously blamed factors of low-stopping power and high reabsorptive losses are likely dwarfed by the losses attributable to efficient, non-radiative Auger recombination. We examine how we reached this conclusion, and how this insight defines the characteristics needed in the next generation of scintillating QD composites.

Pietryga, Jeffrey M.; Padilha, Lazaro A.; Bae, Wan Ki; Klimov, Victor I.; Schaller, Richard D.

2013-05-01

246

Long-term Scintillation Observations of Five Pulsars at 1540 MHz  

E-print Network

From 2001 January to 2002 June, we monitored PSRs B0329+54, B0823+26, B1929+10, B2020+28 and B2021+51 using the Nanshan 25-m radio telescope of Urumqi Observatory to study their diffractive interstellar scintillation (DISS). The average interval between observations was about 9 days and the observation duration ranged between 2 and 6 hours depending on the pulsar. Wide variations in the DISS parameters were observed over the 18-month data span. Despite this, the average scintillation velocities are in excellent agreement with the proper motion velocities. The average two-dimensional autocorrelation function for PSR B0329+54 is well described by a thin-screen Kolmogorov model, at least along the time and frequency axes. Observed modulation indices for the DISS time scale and bandwidth and the pulsar flux density are greater than values predicted for a Kolmogorov spectrum of electron density fluctuations. Correlated variations over times long compared to the nominal refractive scintillation time are observed, suggesting that larger-scale density fluctuations are important. For these pulsars, the scintillation bandwidth as a function of frequency has a power-law index (~3.6) much less than expected for Kolmogorov turbulence (~4.4). Sloping fringes are commonly observed in the dynamic spectra, especially for PSR B0329+54. The detected range of fringe slopes are limited by our observing resolution. Our observations are sensitive to larger-scale fringes and hence smaller refractive angles, corresponding to the central part of the scattering disk.

N. Wang; R. N. Manchester; S. Johnston; B. Rickett; J. Zhang; A. Yusup; M. Chen

2005-01-12

247

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

248

Cosmic ray scintillations. III - The low-frequency limit and observations of interplanetary scintillations  

NASA Technical Reports Server (NTRS)

Statistically significant broad-band fluctuations, or 'scintillations', in the high-energy (about 1 GeV) cosmic ray intensity observed by neutron monitors are interpreted. The scintillations are caused by fluctuations in the interplanetary magnetic field. The theory of the scintillations is presented for the low-frequency limit, below .0001 Hz, including the effects of the earth's rotation on the fluxes observed by the neutron monitors. The observations and the theory are in good agreement. The shapes and amplitudes of the observed spectra and, in particular, a broad enhancement in the power spectrum of the Deep River neutron monitor flux near 1 cpd are related to the interplanetary magnetic field power spectrum and the cosmic ray anisotropy.

Owens, A. J.; Jokipii, J. R.

1974-01-01

249

Climatology of GPS scintillations over Antarctica under solar minimum conditions  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

250

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

251

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

SciTech Connect

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

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

2012-02-15

252

Analysis of the scintillation pattern of the pulsar PSR B0329+54 based on VLBI data at 1650 MHz  

NASA Astrophysics Data System (ADS)

The velocity of motion of the diffraction pattern of the pulsar PSR B0329+54 at 1.6 GHz has been measured. Using a specialized method for the amplitude calibration of the VLBI data, scintillation curves were obtained for the ten ground antennas that took part in the experiment jointly with the orbiting antenna HALCA. The session lasted 12 hours. Our analysis shows that the pulsar has two timescales, 20 and 1 min. The velocity of the scintillation pattern was determined by measuring the shift of the maximum of the scintillation-curve cross-correlation function relative to zero. It turned out that the scintillation spots move independently from each other: there is no ordered motion of the diffraction pattern as a whole. The measured drift velocities are from 25 to 40 km/s; the average magnitude of the drift velocity is 3915 km/s, whereas the magnitude precalculated from the pulsar proper motion taking into account the Earth's motion around the Sun and the Sun's motion with respect to the Local Standard of Rest is 122 km/s. A thin-screen model is unable to provide an adequate description of this behavior.

Semenkov, K. V.; Soglasnov, V. A.; Popov, M. V.

2004-06-01

253

Optical scintillation measurements in a desert environment II: retroreflector links  

NASA Astrophysics Data System (ADS)

The NRL Transportable Atmospheric Testing Suite (TATS) system was used to measure time resolved scintillation over a variety of different ranges at China Lake in December 2010. In this paper an analysis of scintillation effects on retro-reflector links is presented. Scintillation index, power spectral density and probability distribution functions are deduced from the measured irradiance fluctuations. Effects of aperture averaging using multiple retro-reflectors is examined as well as the contribution to the irradiance fluctuations due to enhanced backscatter.

Rabinovich, W. S.; Mahon, R.; Moore, C. I.; Ferraro, M. S.; Suite, M. R.; Burris, H. R., Jr.; Thomas, L. M.

2011-09-01

254

Ionospheric scintillation in Brazil: Analyses and Effects on GNSS Positioning  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

255

Wavelength dependence of radio scintillation: ionosphere and interplanetary irregularities  

Microsoft Academic Search

Recent in situ measurements and scintillation spectra suggest a power law irregularity spectrum in the F region ionosphere with a large outer-scale dimension (100 km). This result is consistent with the 'near-field' scintillation approximation, since Fresnel filtering attenuates irregularity structure larger than (rXz) v2, about 1 km. Consequently, the observed scintillation scale ( 1 km) is much smaller than the

Clifford L. Rufenach

1974-01-01

256

Scintillation-induced Intermittency in SETI  

NASA Astrophysics Data System (ADS)

We use scattering theory, simulations, and empirical constraints on interstellar scintillations to discuss the intermittency of radio signals from extraterrestrial intelligence (ETI). The number of ETI sources in the Galaxy has a direct influence on the expected dynamic range of fluxes in a survey, through inverse square-law effects and, equally importantly, by the number of independent statistical trials made on modulations caused by interstellar scintillations. We demonstrate that scintillations are very likely to allow initial detections of narrowband signals, while making redetections extremely improbable, a result that follows from the skewed, exponential distribution of the modulation. This conclusion holds for relatively distant sources but does not apply to radio SETI toward nearby stars (<~100 pc). Recent SETI has found nonrepeating, narrowband events that are largely unexplained. We consider three models in order to assess these events and to analyze large surveys in general: (model I) radiometer noise fluctuations; (model II) a population of constant Galactic sources that undergo deep fading and amplification due to interstellar scintillation, consistent with ETI transmissions; and (model III) real, transient signals (or hardware errors) of either terrestrial or extraterrestrial origin. We derive likelihood and Bayesian tests of the models for individual events and globally on entire surveys. Applying them to The Planetary Society/Harvard META data, we find that models II and III are both highly preferred to model I, but that models II and III are about equally likely. In the context of model II, the likelihood analysis indicates that candidate events above threshold (~32 ?) are combinations of large amplitude noise fluctuations and scintillation gains, making it highly probable that events seen once will only very rarely be seen again. Ruling out model II in favor of model III is difficult--to do so, many more reobservations (e.g., thousands) are needed than were conducted in META (hundreds) or the reobservation threshold must be much lower than was used in META. We cannot, therefore, rule out the possibility that META events are real, intrinsically steady ETI signals. Our formalism can be used to analyze any SETI program. We estimate the number of reobservations required to rule out model II in favor of model III, taking into account that reobservations made promptly sample the same scintillation gain as in the original detection, while delayed reobservations sample a decorrelated scintillation modulation. The required number is a strong function of the thresholds used in the original survey and in reobservations. We assess optimal methods for applying statistical tests in future SETI programs that use multiple site and multiple beam observations as well as single site observations. We recommend that results be recorded on many more events than have been made to date. In particular, we suggest that surveys use thresholds that are far below the false-alarm threshold that is usually set to yield a small number of noise-induced ``detections'' in a massive survey. Instead, large numbers of events should be recorded in order to (1) demonstrate that background noise conforms to the distribution expected for it; and (2) investigate departures from the expected noise distribution as due to interference or to celestial signals. In this way, celestial signals can be investigated at levels much smaller than the false-alarm threshold. The threshold level for archiving candidate intensities and their corresponding sky positions is best defined in terms of the recording and computational technology that is available at a cost commensurate with other survey costs.

Cordes, James M.; Lazio, Joseph W.; Sagan, Carl

1997-10-01

257

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

PubMed

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

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

2014-11-01

258

Development of polystyrene-based scintillation materials and its mechanisms  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

259

Application of accelerators for the research and development of scintillators  

NASA Astrophysics Data System (ADS)

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

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

2007-08-01

260

Thermostable cocktail for the liquid scintillation counting of heterogeneous media  

SciTech Connect

Considerable analytical errors arise in the liquid scintillation counting of heterogeneous media as a consequence of gel instability. With large sample numbers, a major causative factor of this instability is temperature changes during the counting period. An emulsifier-scintillation cocktail has been designed to provide stable counting conditions for heterogeneous media over a temperature range of 10-30/sup 0/C, i.e., the wide range of temperature likely to be encountered in liquid scintillation counters lacking sample cooling facilities. A comparison was made with a conventional commercially available emulsifier-scintillator.

Noble, R.C. (Hannah Research Inst., Ayr, Scotland); Shand, J.H.; Wagstaff, H.F.

1982-05-01

261

Optics: general-purpose scintillator light response simulation code  

E-print Network

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

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

2000-06-27

262

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

263

Liquid-helium scintillation detection with germanium photodiodes  

SciTech Connect

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

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

1982-05-01

264

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

E-print Network

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

Prikryl, P.

265

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

266

Screening Tests for Women  

MedlinePLUS

... information in Spanish ( en espaol ) Screening tests for women Print a chart of this information Screening tests ... to top More information on Screening tests for women Read more from womenshealth.gov Chlamydia Fact Sheet - ...

267

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.

268

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

269

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

270

Fundamental limits of scintillation detector timing precision  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

271

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

272

Quality control of liquid scintillation counters.  

PubMed

Liquid scintillation counting (LSC) is widely used at LNHB for primary standardization of radionuclides (TDCR method), for secondary calibration and also for source stability studies or radioactive purity measurements. A total of five LSC counters are used for these purposes: two locally developed 3-photodetector counters for the implementation of the TDCR method, two Wallac 1414 counters and one Wallac 1220 Quantulus counter. The quality of the LSC measurements relies on the correct operation of these counters and their traceability to the frequency and time units. PMID:16621583

Jaubert, F; Tarts, I; Cassette, P

2006-01-01

273

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

2014-06-18

274

Cytomegalovirus in pregnancy: to screen or not to screen  

PubMed Central

Background Cytomegalovirus (CMV) infection is now the commonest congenital form of infective neurological handicap, recognized by the Institute of Medicine as the leading priority for the developed world in congenital infection. In the absence of an effective vaccine, universal screening for CMV in pregnancy has been proposed, in order that primary infection could be diagnosed and- potentially- the burden of disability due to congenital CMV prevented. Discussion Universal screening for CMV to identify seronegative women at the beginning of pregnancy could potentially reduce the burden of congenital CMV in one of three ways. The risk of acquiring the infection during pregnancy has been shown to be reduced by institution of simple hygiene measures (primary prevention). Among women who seroconvert during pregnancy, CMV hyperimmune globulin (CMV HIG) shows promise in reducing the risk of perinatal transmission (secondary prevention), and CMV HIG and/ or antivirals may be effective in reducing the risk of clinical sequelae among those known to be infected (tertiary prevention). The reports from these studies have re-ignited interest in universal screening for CMV, but against the potential benefit of these exciting therapies needs to be weighed the challenges associated with the implementation of any universal screening in pregnancy. These include; the optimal test, and timing of screening, to maximize detection; an approach to the management of equivocal results, and the cost effectiveness of the proposed screening program. In this article, we provide an overview of current knowledge and ongoing trials in the prevention, diagnosis and management of congenital CMV. Recognising that CMV screening is already being offered to many patients on an ad hoc basis, we also provide a management algorithm to guide clinicians and assist in counseling patients. Summary We suggest that- on the basis of current data- the criteria necessary to recommend universal screening for CMV are not yet met, but this position is likely to change if trials currently underway confirm that CMV HIG and/ or antivirals are effective in reducing the burden of congenital CMV disease. PMID:23594714

2013-01-01

275

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.

2014-09-09

276

Reflection Guides  

NSDL National Science Digital Library

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

2012-01-01

277

Coatings Guide  

EPA Science Inventory

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

278

TOF-PET detector concept based on organic scintillators  

E-print Network

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

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

2013-05-23

279

TOF-PET detector concept based on organic scintillators  

E-print Network

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

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

2013-01-01

280

Amplitude scintillation studies in the polar region on 250 MHz  

Microsoft Academic Search

In April, July and September 1975 twelve C-141 flights (28 hours of data) were conducted to measure amplitude scintillations on VHF satellite transmissions in the polar region, under auroral conditions. A second aircraft, a KC-135, instrumented for ionospheric\\/auroral research, monitored the conditions of the auroral ionosphere in the ray path to relate scintillation events to auroral conditions in the April

J. Buchau; J. Aarons; J. P. Mullen; E. J. Weber; J. A. Whalen; H. E. Whitney; E. E. Crampton Jr.

1978-01-01

281

Detection of energetic particles and gamma rays Scintillation detectors  

E-print Network

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

Peletier, Reynier

282

Discrimination of naturally occurring radioactive material in plastic scintillator material  

Microsoft Academic Search

Plastic scintillator material is used in many applications for the detection of gamma rays from radioactive material, primarily due to the sensitivity per unit cost compared to other detection materials. However, the resolution and lack of full-energy peaks in the plastic scintillator material prohibits detailed spectroscopy. Therefore, other materials such as doped sodium iodide are used for spectroscopic applications. The

J. H. Ely; R. T. Kouzes; B. D. Geelhood; J. E. Schweppe; R. A. Warner

2004-01-01

283

Gamma spectrometry and plastic-scintillator inherent background  

Microsoft Academic Search

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

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

1988-01-01

284

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

285

Some studies of avalanche photodiode readout of fast scintillators  

SciTech Connect

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

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

1995-08-01

286

Semiconductor scintillator based on photon recycling Serge Luryi n  

E-print Network

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

Luryi, Serge

287

On-line scintillation counting on Meltilex TM basis  

Microsoft Academic Search

A detection system is described for monitoring on-line radioactive process solutions by solid scintillation counting. The system consists of a flow cell with perspex windows coated with the plastic scintillator MeltilexTM. The cell is confined in a chamber welded to a La Calhne container. Thus the detection device is easily attached to, detached from and transported between glove boxes, and

U. Wenzel

1996-01-01

288

Thorium determination by liquid scintillation counting using an extractive cocktail  

Microsoft Academic Search

A simple procedure was developed for the determination of thorium in excretion samples for evaluating Th intakes. After coprecipitation and purification of Th by extraction into an organic phase and backextraction with HCl, the solution was taken to dryness and the residue dissolved in dilute sulfuric acid. Then, Th was extracted into a scintillation cocktail and measured by liquid scintillation

Gabriele Wallner

1996-01-01

289

Measurement of 14C activity by liquid scintillation counting  

Microsoft Academic Search

Measurement of 14C activity in various types of samples has been performed in the Zagreb Radiocarbon Laboratory since 1968 by proportional counting technique and since 2001 by liquid scintillation counting (LSC) technique by using LSC Quantulus 1220. We either prepare benzene or absorb CO2 obtained from the sample in a scintillation cocktail. Various measurement protocols were developed for different types

I. Krajcar Broni?; N. Horvatin?i?; J. Barei?; B. Obeli?

2009-01-01

290

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 65.5N, geographic longitude 12.2E; corrected geomagnetic (CGM) latitude 62.77N), 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

291

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

292

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

293

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

NASA Astrophysics Data System (ADS)

A two-dimensional scintillator-based neutron detector that has a neutron-sensitive area of 256256 mm2 with a pixel size of 4 mm was developed. The detector was designed to be compact and modular with the smallest dead area for the SENJU time-of-flight Laue single-crystal diffractometer to be constructed in the Materials and Life Science Experimental Facility at the Japanese Proton Accelerator Research Complex. The detector employed wavelength-shifting (WLS) fibres to collect scintillation light generated in a neutron-sensitive scintillator. The 64 WLS fibres with a diameter of 1 mm were regularly spaced at a pitch of 4 mm both in the x and y directions to produce a detector with a large neutron-sensitive area and a small number of electronics channels. Two ZnS/10B2O3 scintillator screens with an optimised scintillator thickness sandwiched the cross-arranged WLS fibre arrays to ensure a high detection efficiency for thermal neutrons. The prototype detector exhibited a detector efficiency of 401%(meanSD) for 1.6 neutrons and a 60Co gamma-ray sensitivity of 6.00.110-6, which fulfilled the required detector specifications for SENJU.

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

2012-09-01

294

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

295

Optimization of light collection from crystal scintillators for cryogenic experiments  

E-print Network

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

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

2014-01-01

296

Optimization of light collection from crystal scintillators for cryogenic experiments  

E-print Network

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

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

2014-02-10

297

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

298

Ionospheric irregularities causing scintillation of GHz frequency radio signals  

NASA Technical Reports Server (NTRS)

Consideration of the recently observed phenomenon of scintillation of satellite signals at GHz frequency range. Based on the scintillation data and results from in situ measurements, several ionospheric irregularity models with different power spectra are studied. Scintillation index is computed for the various models and compared with observed results. Both magnitude and frequency dependence of the scintillation index are investigated. It is found that a thick irregularity slab of the order of 200 km with an electron density fluctuation of about 20 per cent of its background value and with a nonmonotonic power spectrum may account for the maximum observed values of the scintillation index as well as its frequency dependence. Some future observations and measurements are suggested.

Wernik, A. W.; Liu, C. H.

1974-01-01

299

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

300

Measuring scintillation light using Visible Light  

NASA Astrophysics Data System (ADS)

A new search for the neutron electric dipole moment (EDM) using ultra cold neutrons proposes an improvement on the neutron EDM by two orders of magnitude over the current limit (to 10-28 e*cm). Detection of scintillation light in superfluid ^4He is at the heart of this experiment. One possible scheme to detect this light is to use wavelength-shifting fibers in the superfluid ^4He to collect the scintillation light and transport it out of the measuring cell. The fiber terminates in a visible light photon counter (VLPC). VLPCs are doped, silicon based, solid state photomultipliers with high quantum efficiency (up to 80%) and high gain ( 40000 electrons per converted photon). Moreover, they are insensitive to magnetic fields and operate at temperatures of 6.5K. A test setup has been assembled at Duke University using acrylic cells wrapped in wavelength-shifting fibers that terminate on VLPCs. This setup is being used to evaluate the feasibility of this light detection scheme. The results obtained in multiple experiments done over the past summer (2006) and the current status of the project will be presented at the conference.Reference:A New Search for the Neutron Electric Dipole Moment, funding pre-proposal by the EDM collaboration; R. Golub and S. Lamoreaux, Phys. Rep. 237, 1 (1994).

Chavarria, Alvaro

2006-11-01

301

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

302

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

303

Plasma Screen Floating Mount  

DOEpatents

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

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

2004-10-26

304

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 (62.39N, 145.15W) 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

305

Extended ionospheric amplitude scintillation model for GPS receivers  

NASA Astrophysics Data System (ADS)

scintillation is a phenomenon that occurs after sunset, especially in the low-latitude region, affecting radio signals that propagate through the ionosphere. Depending on geophysical conditions, ionospheric scintillation may cause availability and precision problems to Global Navigation Satellite System users. The present work is concerned with the development of an extended model for describing the effects of the amplitude ionospheric scintillation on GPS receivers. Using the ?-? probabilistic model, introduced by previous authors in different contexts, the variance of GPS receiver tracking loop error may be estimated more realistically. The proposed model is developed with basis on the ?-? parameters and also considering correlation between amplitude and phase scintillation. Its results are interpreted to explain how a receiver may experience different error values under the influence of ionospheric conditions leading to a fixed scintillation level S4. The model is applied to a large experimental data set obtained at So Jos dos Campos, Brazil, near the peak of the equatorial anomaly during high solar flux conditions, between December 2001 and January 2002. The results from the proposed model show that depending on the ?-? pair, moderate scintillation (0.5 ? S4 ? 0.7) may be an issue for the receiver performance. When S4 > 0.7, the results indicate that the effects of scintillation are serious, leading to a reduction in the receiver availability for providing positioning solutions in approximately 50% of the cases.

Oliveira Moraes, Alison; Costa, Emanoel; Paula, Eurico Rodrigues; Perrella, Waldecir Joo.; Monico, Joo. Francisco Galera

2014-05-01

306

Development of scintillation materials for medical imaging and other applications  

SciTech Connect

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. [Scintillation Materials Research Center, University of Tennessee (United States)

2013-02-05

307

Low/Mid-latitude Ionospheric irregularities and scintillation climatology  

NASA Astrophysics Data System (ADS)

Ionospheric scintillation occur when radio signals propagate through an irregular ionosphere (e.g., plasma bubbles). Since plasma bubbles are regions of depleted ion and electron densities, a plasma bubble located on the satellite-to-ground signal path will cause radio signals to fluctuate in phase and amplitude. Ionospheric scintillation data were analyzed in the magnetic latitudinal field-of-view 29 N -13.4 N, observed by a stand-alone SCINDA (Scintillation Network Decision Aid) - GPS receiver at Helwan, Egypt (29.86 N, 31.32 E). A minimum 20 elevation cut off angle has been set in order to minimize the multipath effect. During the enhancing phase of the current solar cycle 24 (years 2010, 2011, 2012 and 2013), the behaviour of the scintillation occurrence were characterized. The seasonal, annual and solar cycle variation of scintillation occurrence is investigated together with the Total Electron Content (TEC), to put in evidence the relation between the electron density gradients and the ionospheric irregularities causing scintillation. This study considers a first step to develop a scintillation climatology over Northern Africa.

Abdallah, Amr; Groves, K. M.; Mahrous, Ayman; Hussein, Fayrouz

308

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

309

Cost-effective segmented scintillating converters for hard x rays  

NASA Astrophysics Data System (ADS)

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

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

1996-07-01

310

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

311

Induced activity in scintillation detectors in space  

NASA Astrophysics Data System (ADS)

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

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

1991-05-01

312

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 310-5.

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

313

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 photodetectorsSilicon 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.; Gttlicher, P.; Markin, O.; Reinecke, M.; Tarkovsky, E.; Calice Collaboration

2010-11-01

314

High-Z organic-scintillation solution  

SciTech Connect

In the present experiment, an attempt is made to raise the average Z of a scintillation solution with as little attendant quenching as possible. Since high-Z atoms quench by means of a close encounter, such encounters are minimized by the use of alkyl groups substituted on the solvent, solute, and heavy atoms. The aromatic compound 1,2,4-trimethylbenzene (pseudocumene) is used as the solvent; 4,4''-di(5-tridecyl)-p-terphenyl (SC-180) as the solute; and tetrabutyltin as the high-Z material. To establish the validity of our ideas, various experiments have been performed with less protected solvents, and heavy atoms. These include benzene, toluene, p-terphenyl, bromobutane, and bromobenzene.

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

1983-01-01

315

Scintillating glass fiber-optic neutron sensors  

SciTech Connect

Pacific Northwest Laboratory (PNL) has fabricated cerium-activated lithium silicate scintillating fibers via a hot-downdraw process. These fibers, which, as produced, typically have a transmission length (e{sup {minus}1} length) of greater than 2 meters, are found to undergo aging when subjected to room air. The aging, which is complete in a few weeks, reduces the transmission length to the order of 0.5 meter. Because of the high alkali content of the glass (on the order of 20--30 mole % lithia), we have attributed this aging to aqueous corrosion oat the polymer cladding/glass interface. changes in transmission with chemical treatment of the surface support the corrosion model. Fiber transmission performance has been preserved by modifying the hot-downdraw to a double crucible to produce glass-on-glass waveguides.

Abel, K.H.; Arthur, R.J.; Bliss, M. [and others

1994-04-01

316

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; lvarez, V; Borges, F I G; Crcel, S; Castel, J; Cebrin, S; Cervera, A; Conde, C A N; Dafni, T; Dias, T H V T; Daz, J; Esteve, R; Evtoukhovitch, P; Fernandes, L M P; Ferrario, P; Ferreira, A L; Freitas, E D C; Gil, A; Gmez, H; Gmez-Cadenas, J J; Gonzlez-Daz, D; Gutirrez, 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; Luzn, G; Mar, A; Martn-Albo, J; Martnez, A; Moiseenko, A; Monrabal, F; Monserrate, M; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Muoz; da Luz, H Natal; Navarro, G; Nebot-Guinot, M; Palma, R; Prez, J; Aparicio, J L Prez; Ripoll, L; Rodrguez, A; Rodrguez, J; Santos, F P; Santos, J M F dos; Segu, L; Serra, L; Simn, A; Sofka, C; Sorel, M; Toledo, J F; Toms, A; Torrent, J; Tsamalaidze, Z; Veloso, J F C A; Villar, J A; Webb, R C; White, J; Yahlali, N

2014-01-01

317

Measurement of the liquid scintillator nonlinear energy response to electron  

E-print Network

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 in laboratory the nonlinearity of the Linear Alkyl Benzene based liquid scintillator, which is used in Daya Bay and will be used in JUNO, via 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 $\\theta_{13}$, $\\Delta m^2$, and reactor neutrino spectrum measurements at Daya Bay.

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

2014-03-12

318

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. lvarez; F. I. G. Borges; S. Crcel; J. Castel; S. Cebrin; A. Cervera; C. A. N. Conde; T. Dafni; T. H. V. T. Dias; J. Daz; R. Esteve; P. Evtoukhovitch; L. M. P. Fernandes; P. Ferrario; A. L. Ferreira; E. D. C. Freitas; A. Gil; H. Gmez; J. J. Gmez-Cadenas; D. Gonzlez-Daz; R. M. Gutirrez; 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. Luzn; A. Mar; J. Martn-Albo; A. Martnez; A. Moiseenko; F. Monrabal; M. Monserrate; C. M. B. Monteiro; F. J. Mora; L. M. Moutinho; J. Muoz Vidal; H. Natal da Luz; G. Navarro; M. Nebot-Guinot; R. Palma; J. Prez; J. L. Prez Aparicio; L. Ripoll; A. Rodrguez; J. Rodrguez; F. P. Santos; J. M. F. dos Santos; L. Segu; L. Serra; A. Simn; C. Sofka; M. Sorel; J. F. Toledo; A. Toms; J. Torrent; Z. Tsamalaidze; J. F. C. A. Veloso; J. A. Villar; R. C. Webb; J. White; N. Yahlali

2014-09-09

319

Light output of EJ228 scintillation neutron detectors.  

PubMed

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

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

2011-02-01

320

Scintillation of liquid helium for low-energy nuclear recoils  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

321

Scintillations of optical vortex in randomly inhomogeneous medium  

E-print Network

The comparative numerical and analytical analysis of scintillation indices of the vortex Laguerre-Gaussian beam and the non-vortex doughnut hole and Gaussian beams propagating in the randomly inhomogeneous atmosphere has been performed. It has been found that the dependence of the scintillation index at the axis of the optical vortex on the turbulence intensity at the path has the form of a unit step. It has been shown that the behavior of scintillations in the cross sections of vortex and non-vortex beams differs widely.

Aksenov, Valerii P

2014-01-01

322

Calibration of Small Plastic Scintillators for Imaging Applications  

SciTech Connect

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

Pozzi, S.

2005-01-19

323

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

324

Articulation Disorders: A Guide to Program Administration and Case Management for Speech Clinicians in Public Schools.  

ERIC Educational Resources Information Center

Intended to assist speech clinicians in the public schools, the guide provides information on establishing accountability for services to children with articulation disorders. Described are procedures involved in initial screening (such as teacher referral and rapid screening), assessment (including audiometric screening and oral peripheral

Ginn, Mary E.

325

Frequency dependence of ionospheric scintillations and its application to spectral estimation of electron density irregularities  

Microsoft Academic Search

Analytical results of simultaneous observations of 136 MHz and 1.7 GHz ionospheric scintillations at midlatitudes during summer are presented. The causal relation between scintillation occurrence and ionospheric condition is discussed to examine the influences of spread-F and sporadic-E on the scintillation. The diurnal variations of scintillation occurrences show that the time of maximum occurrence for the nighttime scintillation depends on

M. Fujita; K. Sinno; T. Ogawa

1982-01-01

326

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

327

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

328

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

329

Science: Kindergarten. Interim Guide.  

ERIC Educational Resources Information Center

This guide is one of a set of 10 science guides, each covering a separate grade in Manitoba, together covering kindergarten through grade 9. The guides have been designed to provide a framework for building scientific concepts and developing the learning of process skills. They replace an earlier set of guides dated 1979. Each guide is essentially

Manitoba Dept. of Education and Training, Winnipeg.

330

The response of scintillators to heavy ions: 1, Plastics  

SciTech Connect

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

McMahan, M.A.

1987-10-01

331

Time profile of the scintillation from liquid and gaseous xenon  

NASA Astrophysics Data System (ADS)

The decay time profile of vacuum ultraviolet scintillation induced by electronic recoils has been studied for liquid and gaseous xenon. The scintillation light from xenon excited by a gamma source was measured by using two vacuum ultraviolet sensitive photomultipliers, one for detecting scintillation and the other for counting photons of weak monochromatic light. The analysis results based on the time-correlated single photon counting method show that the time profile in the 176 nm scintillation decay curve for liquid xenon is consistent with a single exponential component and the decay time constant is 31.51.3 ns. This constant does not change significantly for pressure ranges between 90 kPa and 130 kPa. There is no emission wavelength dependence of the decay constant. The result corresponds to an average on electronic recoil energies up to 1.3 MeV.

Murayama, Ikuko; Nakamura, Shogo

2014-11-01

332

0 m 5 10 15 20 W/Pb scintillator  

E-print Network

0 m 5 10 15 20 W/Pb scintillator sandwich, shash- lik WLS readout with PMTs; energy-cluster pre-trigger Electromagnetic Calorimeter7 superlayers of honeycomb drift chambers, 5 and 10mm cells Outer Tracker High rate

333

Photonic Crystals: Enhancing the Light Output of Scintillation Based Detectors  

E-print Network

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

Knapitsch, Arno Richard

334

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 the plastic scintillators to fast neutrons.

Abbott, David

2012-03-01

335

Investigation of Plastic Scintillator Detector Configurations for Neutron Studies  

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

336

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 the plastic scintillator to fast neutrons.

Abbott, David

2012-03-01

337

Encapsulated scintillators monitor /sup 3/H-solute concentrations  

SciTech Connect

The short range of the /sup 3/H beta allows shielding of microbeds of scintillator by a several um thick coating of a water based gel. Gels may be used which are permeable to a wide variety of tritiated molecules. Thus, the light output of a mixture of the coated beads and a solution of the tritiated compound is proportional to the solution concentration of the tritiated substance. The mixture may also contain particles to which the gel is impermeable, such as cells, vesicles, large proteins, etc., but which can alter the concentration of the tritiated compound by uptake or release. In this case, the light output monitors the fractional uptake of the tritiated material. The design criteria for encapsulating the scintillators and dynamically monitoring the scintillation output are discussed. A simple method for encapsulating plastic scintillator microbeads, suitable for monitoring slow concentration changes, is described and tested.

Kirk, G.; Gruner, S.

1982-02-01

338

Multistation analysis of VHF radio wave scintillations at low latitudes  

NASA Astrophysics Data System (ADS)

Simultaneous observations of VHF-ionospheric scintillations at Bhopal, Varanasi and Agra, during the period (January 1991-December 1991) have been reported. Nocturnal variation of occurrence of scintillations is found to be higher at Bhopal as compared to that at Varanasi and Agra. Under the geomagnetic disturbances the scintillations are suppressed in pre-midnight period at all the three stations. Severity of suppression is found to be more at Bhopal. The storms with the D(sub st) value below -100nT, reaching in local nighttime or in very early morning hours are found to be most effective in giving rise to the scintillations in post-midnight period. The results have been interpreted in terms of (1) F-region irregularities associated with spread-F and (2) coupling of high latitude and magnetospheric current systems with equatorial electric field.

Kumar, Sushil; Singh, A. K.; Chauhan, Pawan; Gwal, A. K.; Singh, Birbal; Singh, R. P.

1993-08-01

339

The effects of dissolved methane upon liquid argon scintillation light  

E-print Network

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 ...

Alexander, T

340

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 Committee ...

341

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

342

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

343

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

344

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

345

Cervical Cancer Screening  

MedlinePLUS

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

346

Breast Cancer Screening  

MedlinePLUS

... cancer screening: Cancer Screening Overview General Information About Breast Cancer Breast cancer is a disease in which malignant (cancer) cells ... Cancer Treatment Genetics of Breast and Ovarian Cancer Breast cancer is the second leading cause of death from ...

347

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

NASA Technical Reports Server (NTRS)

Three observations of radio star intensity fluctuations at UHF are reported for HF ionospheric modification experiments carried out at the Arecibo Observatory. Two observations at 430 MHz and one at 1400 MHz suggest that the the thin phase screen theory is a good approximation to the observed power spectra. It is noted, however, that the theory has to be extended to include antenna filtering. This type of filtering is important for UHF radio star scintillations since the antenna usually has a narrow beamwidth. HF power densities of less than 37 microwatts/sq m incident on the ionosphere give rise to electron density irregularities larger than 13% of the ambient density (at 260 km) having scale sizes of approximately 510 m perpendicular to the geomagnetic field. The irregularities are found to form within 20-25 s after the HF power is turned on. The drift velocities of the irregularities can be estimated from the observed power spectra.

Frey, A.; Gordon, W. E.

1982-01-01

348

Light collection in scintillation detector composites for neutron detection  

Microsoft Academic Search

With the goal of developing neutron detectors of high detection efficiency and fast response, the authors have been investigating the heterogeneous combination of neutron-conversion materials in a plastic or liquid scintillation matrix. One such combination consists of thin-wall glass microspheres filled with high pressure ³He gas dispersed in plastic scintillator. The authors have now developed glass formulations that are capable

G. F. Knoll; T. F. Knoll; T. M. Henderson

1988-01-01

349

Hadronic shower development in Iron-Scintillator Tile Calorimetry  

Microsoft Academic Search

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

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

2000-01-01

350

Monitoring the solar-terrestrial environment using interplanetary scintillation  

NASA Astrophysics Data System (ADS)

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

Daly, N.

351

A new X-ray scintillator for digital radiography  

Microsoft Academic Search

We report a new scintillator based on a transparent ceramic of Lu2O3:Eu. The material has an extremely high density of 9.4 g\\/cm3 and a light output comparable to CsI:Tl. Its narrow band emission at 610 nm perfectly matches the spectral response of CCDs. To enhance the spatial and contrast resolution, we have developed a special process to pixelate the scintillator

V. V. Nagarkar; S. V. Tipnis; S. R. Miller; A. Lempicki; C. Brecher; P. Szupryczynski; H. Lingertat

2001-01-01

352

Large area silicon avalanche photodiodes for scintillation detectors  

NASA Astrophysics Data System (ADS)

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

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

1990-03-01

353

Large area silicon avalanche photodiodes for scintillation detectors  

Microsoft Academic Search

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

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

1990-01-01

354

Plastic scintillator bar with WLS fiber calorimeter for neutrino physics  

NASA Astrophysics Data System (ADS)

A calorimeter with 180 plastic scintillator bars interleaved with 180 iron bars has been built and tested with pion and electron beams at CERN. The plastic scintillator bars, coupled to wavelength shifting fibers, are read with multi-anode PMTs and Amplitude-Time-Pattern self-triggering digitizing electronics. This type of calorimeter could be well suited for the construction of large, many kton detectors for neutrino oscillation experiments on the CERN to Gran Sasso CNGS beam or for the neutrino factory.

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

2001-04-01

355

Status report on dark matter search with low activity scintillators  

NASA Astrophysics Data System (ADS)

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

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

1994-05-01

356

Radiation damage in plastic scintillators and optical fibers  

Microsoft Academic Search

The paper presents experimental results on a radiation damage study of some plastic scintillators BC-400, BC-404, BC-408, NE-102a, NE-110 (on the base of polyvinyltoluene) in comparison with polystyrene-based ones and some wavelength shifting fibers-Y-7, BCF-92a, RK-27, RR-26. Our measurements show that scintillators based on granulated PSM-115 polystyrene and RK-27 fibers were the most radiation resistant among those investigated.

Yu. M. Protopopov; V. G. Vasil'chenko

1995-01-01

357

Analysis of the response of capture-gated organic scintillators  

Microsoft Academic Search

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

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

2005-01-01

358

Analysis of the response of capture-gated organic scintillators  

Microsoft Academic Search

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

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

2004-01-01

359

Measurement of 14C activity by liquid scintillation counting.  

PubMed

Measurement of (14)C activity in various types of samples has been performed in the Zagreb Radiocarbon Laboratory since 1968 by proportional counting technique and since 2001 by liquid scintillation counting (LSC) technique by using LSC Quantulus 1220. We either prepare benzene or absorb CO(2) obtained from the sample in a scintillation cocktail. Various measurement protocols were developed for different types of vials. Examples of environmental (14)C activities in atmospheric CO(2) and in biological samples are presented. PMID:19243962

Krajcar Broni?, I; Horvatinci?, N; Baresi?, J; Obeli?, B

2009-05-01

360

Fluorescence decay-time constants in organic liquid scintillators.  

PubMed

The fluorescence decay-time constants have been measured for several scintillator mixtures based on phenyl-o-xylylethane (PXE) and linear alkylbenzene (LAB) solvents. The resulting values are of relevance for the physics performance of the proposed large-volume liquid scintillator detector Low Energy Neutrino Astronomy (LENA). In particular, the impact of the measured values to the search for proton decay via p-->K(+)nu is evaluated in this work. PMID:19405650

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

2009-04-01

361

Theory of the field-controlled scintillation detector  

Microsoft Academic Search

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

M. I. Ryazanov

1999-01-01

362

Decay time and light yield measurements for plastic scintillating fibers  

Microsoft Academic Search

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

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

1990-01-01

363

Colorectal cancer screening.  

PubMed

Mortality from colorectal cancer can be reduced by early diagnosis and by cancer prevention through polypectomy. These NCCN Guidelines for Colorectal Cancer Screening describe various colorectal screening modalities and recommended screening schedules for patients at average or increased risk of developing colorectal cancer. In addition, the guidelines provide recommendations for the management of patients with high-risk colorectal cancer syndromes, including Lynch syndrome. Screening approaches for Lynch syndrome are also described. PMID:24335688

Burt, Randall W; Cannon, Jamie A; David, Donald S; Early, Dayna S; Ford, James M; Giardiello, Francis M; Halverson, Amy L; Hamilton, Stanley R; Hampel, Heather; Ismail, Mohammad K; Jasperson, Kory; Klapman, Jason B; Lazenby, Audrey J; Lynch, Patrick M; Mayer, Robert J; Ness, Reid M; Provenzale, Dawn; Rao, M Sambasiva; Shike, Moshe; Steinbach, Gideon; Terdiman, Jonathan P; Weinberg, David; Dwyer, Mary; Freedman-Cass, Deborah

2013-12-01

364

Screening for Lung Cancer  

PubMed Central

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

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

2013-01-01

365

Response of plastic scintillators to low-energy photons  

NASA Astrophysics Data System (ADS)

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

Peralta, Luis; Rgo, Florbela

2014-08-01

366

A study of GPS ionospheric scintillations observed at Shenzhen  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

367

Fast Neutron Detection with 6Li-loaded Liquid Scintillator  

E-print Network

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

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

2011-06-22

368

RNA interference screening demystified  

Microsoft Academic Search

Genetic screens, where the effects of modifying gene function on cell behaviour are assessed in a systematic fashion, have for some time provided useful information to those interested in disease pathogenesis and treatment. Genetic screens exploiting the phenomenon of RNA interference (RNAi) are now becoming commonplace. This article explains the different RNAi screen formats and describes some of the applications

C J Lord; S A Martin; A Ashworth

2009-01-01

369

First Trimester Screening  

Microsoft Academic Search

Screening for aneuploidy has traditionally been reserved for women of advanced maternal age. More recent advances in serum screening and ultrasound technology have allowed women of all ages to be offered screening in the second and even first trimester. These methods and their effectiveness are discussed.

Sarah C. Ellestad; Steven R. Wells; Jeffrey A. Kuller

2005-01-01

370

Breast cancer screening  

Microsoft Academic Search

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

Kathleen M. Harris; Victor G. Vogel

1997-01-01

371

Mental Health Screening and Assessment in Juvenile Justice  

Microsoft Academic Search

Citation: Grisso, T., Vincent, G., & Seagrave, D. (eds.) (2005). Handbook of mental health screening and assessment in juvenile justice. New York: Guilford Press. ISBN 1593851324, 9781593851323.\\u000aSummary: A complete, authoritative guide for professionals charged with identifying the mental health needs of juveniles in the justice system, this volume offers a practical primer on screening and assessment together with in-depth

Thomas Grisso; Gina M. Vincent; Daniel Seagrave

2005-01-01

372

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

SciTech Connect

The capture and transmission of light from an event through a scintillating fiber is somewhat different than in conventional optical waveguide applications. A theoretical all-ray model that depends on surface and bulk loss factors is developed for this transmission. The capture fraction can be significantly greater than that predicted on the basis of meridional rays alone and the gross loss is nonexponential for short distances (less than or of the order of one 1/e distance). The latter phenomenon occurs because high-angle and skew rays are more rapidly attenuated than meridional rays.

Abel, K.H.; Arthur, R.J.; Bliss, M. [and others

1993-10-01

373

Screening and preventable illness.  

PubMed

If an agent does not discount the future at a constant rate, as in some forms of myopia, her optimal strategy is unattainable without some commitment device. We apply this familiar idea to a model of screening and disease prevention, and explore how financial incentives can correct suboptimal health choices. In general, myopia need not imply under-screening. While the optimal intervention for prevention effort is a state-invariant subsidy, the optimal intervention for screening may involve a tax or a subsidy. When screening and prevention are coincident, a simple and practical subsidy equal to one minus the discount factor to both screening and intervention is indicated. PMID:11758049

Byrne, M M; Thompson, P

2001-11-01

374

Screening for Proteinuria and Chronic Kidney Disease Risk Factors in Kinshasa: A World Kidney Day 2007 Study  

Microsoft Academic Search

Background: Although screening programs for chronic kidney disease (CKD) may be of great value, these programs are not yet implemented in the Democratic Republic of Congo. This study focused on proteinuria and examined its prevalence in terms of the number needed to screen for the different risk factors of CKD. Such knowledge would guide the utility of population screening to

Ernest K. Sumaili; Nazaire M. Nseka; Franois B. Lepira; Jean Marie Krzesinski; Jean Robert R. Makulo; Justine B. Bukabau; Jose B. Nkoy; Vieux M. Mokoli; Murielle M. Longokolo; Julie A. Owandjalola; Patrick K. Kayembe

2008-01-01

375

Excitonic effects in oxyhalide scintillating host compounds  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

376

Progress with the MICE scintillating fiber trackers  

NASA Astrophysics Data System (ADS)

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

Overton, Edward

2013-12-01

377

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

PubMed Central

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

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

2010-01-01

378

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

SciTech Connect

The radiological examination of water requires a rapid screening technique that permits the determination of the gross alpha and beta activities of each sample in order to decide if further radiological analyses are necessary. In this work, the use of a low background liquid scintillation system (Quantulus 1220) is proposed to simultaneously determine the gross activities in water samples. Liquid scintillation is compared to more conventional techniques used in most monitoring laboratories. In order to determine the best counting configuration of the system, pulse shape discrimination was optimized for 6 scintillant/vial combinations. It was concluded that the best counting configuration was obtained with the scintillation cocktail Optiphase Hisafe 3 in Zinsser low diffusion vials. The detection limits achieved were 0.012 Bq L{sup -1} and 0.14 Bq L{sup {minus}1} for gross alpha and beta activity respectively, after a 1:10 concentration process by simple evaporation and for a counting time of only 360 min. The proposed technique is rapid, gives spectral information, and is adequate to determine gross activities according to the World Health Organization (WMO) guideline values.

Sanchez-Cabeza, J.A.; Pujol, Ll. [Universitat Autonoma de Barcelona, Bellaterra (Spain)

1995-05-01

379

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

PubMed

The radiological examination of water requires a rapid screening technique that permits the determination of the gross alpha and beta activities of each sample in order to decide if further radiological analyses are necessary. In this work, the use of a low background liquid scintillation system (Quantulus 1220) is proposed to simultaneously determine the gross activities in water samples. Liquid scintillation is compared to more conventional techniques used in most monitoring laboratories. In order to determine the best counting configuration of the system, pulse shape discrimination was optimized for 6 scintillant/vial combinations. It was concluded that the best counting configuration was obtained with the scintillation cocktail Optiphase Hisafe 3 in Zinsser low diffusion vials. The detection limits achieved were 0.012 Bq L-1 and 0.14 Bq L-1 for gross alpha and beta activity respectively, after a 1:10 concentration process by simple evaporation and for a counting time of only 360 min. The proposed technique is rapid, gives spectral information, and is adequate to determine gross activities according to the World Health Organization (WHO) guideline values. PMID:7730064

Sanchez-Cabeza, J A; Pujol, L

1995-05-01

380

A capability for monitoring effluent tritium with liquid scintillation/robotics  

SciTech Connect

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

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

1993-01-01

381

Cost Utility Analysis of Radiographic Screening for an Orbital Foreign Body before MR Imaging  

Microsoft Academic Search

BACKGROUND AND PURPOSE:Our purpose was to evaluate the cost-effectiveness of clin- ical versus radiographic screening for an orbital foreign body before MR imaging. METHODS: Costs of screening were determined on the basis of published reports, disability rating guides, and a practice survey. Base case estimates were derived from published guide- lines. A single-state change model was constructed using social cost

David J. Seidenwurm; Charles H. McDonnell; Narasimhachari Raghavan; Jonathan Breslau

2000-01-01

382

Intimate Partner Violence Screening Tools  

Microsoft Academic Search

Context: Intimate partner violence (IPV) screening remains controversial. Major medical organiza- tions mandate screening, whereas the U.S. Preventive Services Task Force (USPSTF) cautions that there is insufficient evidence to recommend for or against screening. An effective IPV screening program must include a screening tool with sound psychometric properties. A systematic review was conducted to summarize IPV screening tools tested in

Rebecca F. Rabin; Jacky M. Jennings; Jacquelyn C. Campbell; Megan H. Bair-Merritt

2009-01-01

383

Covariance Assisted Screening and Estimation  

E-print Network

Consider a linear model regression model, where the regression coefficient vector is unknown and it is of interest to separate its nonzero coordinates from the zero ones (i.e., variable selection). Motivated by examples in long-memory time series and change-point problem, we are primarily interested in the case where the Gram matrix is non-sparse but is sparsifiable by a finite order linear filter. We focus on the regime where signals are both rare and weak so that successful variable selection is very challenging but is still possible. We approach the problem by a new procedure called the Covariance Assisted Screening and Estimation (CASE). CASE first uses a linear filtering to reduce the original setting to a new regression model where the corresponding Gram (covariance) matrix is sparse. The new covariance matrix induces a sparse graph, which guides us to screen variables without visiting all the submodels. By interacting with the signal sparsity, the graph enables us to decompose the original problem into...

Ke, Tracy; Fan, Jianqing

2012-01-01

384

Automated Groundwater Screening  

SciTech Connect

The Automated Intruder Analysis has been extended to include an Automated Ground Water Screening option. This option screens 825 radionuclides while rigorously applying the National Council on Radiation Protection (NCRP) methodology. An extension to that methodology is presented to give a more realistic screening factor for those radionuclides which have significant daughters. The extension has the promise of reducing the number of radionuclides which must be tracked by the customer. By combining the Automated Intruder Analysis with the Automated Groundwater Screening a consistent set of assumptions and databases is used. A method is proposed to eliminate trigger values by performing rigorous calculation of the screening factor thereby reducing the number of radionuclides sent to further analysis. Using the same problem definitions as in previous groundwater screenings, the automated groundwater screening found one additional nuclide, Ge-68, which failed the screening. It also found that 18 of the 57 radionuclides contained in NCRP Table 3.1 failed the screening. This report describes the automated groundwater screening computer application.

Taylor, Glenn A.; Collard, Leonard, B.

2005-10-31

385

A scintillating fission detector for neutron flux measurements  

SciTech Connect

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

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

2010-01-01

386

Screening of colorectal cancer.  

PubMed

Cost-effectiveness analyses have shown that the cost per year of life saved by screening with any of the tests recommended is reasonable by US standards. Although the specific results vary among analyses, in general the marginal cost-effectiveness of this screening is less than $25,000 per year of life saved. Screening for CRC was among the highest ranked services in an analysis of the value of preventive services based on the burden of disease prevented and cost-effectiveness. Although the up-front costs vary by screening modality, the long-term cost-effectiveness is similar across screening tests, so that decisions about which options to include--in the long run and from the perspective of society--do not need to be affected heavily by costs. Costs increase out of proportion to benefits with shorter intervals between screening examinations. Screening has provided great opportunities. Screening can prevent CRC by polypectomy and find early-stage cancers for treatment with less morbidity. Screening can reduce the burden of treating advanced cancers and can identify families at increased risk. Screening also has provided a better understanding of the biology of CRC. Screening for CRC should be part of a complete prevention program that includes a healthy lifestyle and familial risk assessment. Individuals with increased familial risk require special screening approaches, whereas individuals with average risk can have more standard screening. The average-risk individuals can be stratified further into persons who require intensive follow-up and persons who require less intensive or no follow-up at all. We are beginning to learn how to apply screening and surveillance approaches based on risk stratification for a more cost-effective approach to conserve resources and reduce complications and costs. Chemoprevention can be added to the program when substantial benefit of agents has been demonstrated. We have a better understanding of the biology of CRC and the technology to intervene in that biology to make a difference in the lives of many people. We have the concepts and technology to reduce substantially the mortality for CRC and even prevent it entirely. Newer screening tests or others yet to be developed may, with time, replace the modern options. Screening should take place with the tests currently available and not wait until something better comes along. In this way, needless suffering and loss of life can be avoided for this leading cause of cancer death. Screening may become even more successful if the promise of new technologies is confirmed and they enter clinical practice. In the last analysis, the best test is the one that gets done and gets done immediately. PMID:16226687

Winawer, Sidney J

2005-10-01

387

Emergency Guide Tuscarawas Campus  

E-print Network

Services & Tuscarawas Business Affairs & Operations Updated January 1, 2014 Contact: JFuto@kent.edu #12, this guide is a template for the individual response by students, faculty and staff at the Tuscarawas Campus of the Emergency Guide The purpose of the guide is to: Serve as a quick reference guide for students, faculty

Khan, Javed I.

388

Indium-111-Photofrin-II scintillation scan  

SciTech Connect

Photodynamic therapy is under intense investigation as an adjuvant treatment for malignant glial tumors of the central nervous system. Photofrin-II (HpD-II) is currently the most actively investigated photosensitizing agent. A crucial issue regarding the safe and efficacious usage of HpD-II-based photodynamic therapy is the individual in vivo kinetics of tumor uptake and retention, compared with normal brain clearance. The optimal time for photoactivation of sensitized tumor must be known to ensure a high target-to-nontarget ratio, resulting in the maximal tumor destruction while preserving normal brain. Our laboratory developed a radionuclide scan based on 111indium (111In)-labeled HpD-II to evaluate HpD-II localization and clearance noninvasively within a canine model of intracerebral gliosarcoma. Synthesis of the 111In-HpD-II complex in greater than 90% yield is achieved by a simple, rapid labeling method. Radiochemical purity and stability were verified by high-performance liquid chromatography. Using the canine model of intracerebral gliosarcoma, we followed the uptake of 111In-HpD-II in tumors with serial scintillation scanning. Localization of the tumor by 111In-HpD-II has been verified by contrast-enhanced computed tomographic scan followed by gross and histological examination of the enhancing brain region. Total body biodistribution of 111In-HpD-II at various times after injection has been evaluated. The ratio of uptake in tumor compared with surrounding brain peaked at 72 hours after injection. The knowledge of regional distribution and concentration of a photosensitizing agent within a tumor mass and surrounding brain allows for the most efficacious timing and localization of a photoactivating source.

Origitano, T.C.; Karesh, S.M.; Reichman, O.H.; Henkin, R.E.; Caron, M.J.

1989-04-01

389

Transmission and scintillation measurements for a summertime desert environment  

NASA Astrophysics Data System (ADS)

An infrared (IR) or optical signal propagating along a 'line-of-sight' horizontal or slant path near the earth's surface can encounter substantial perturbations. These perturbations result in refractive distortions (low-frequency modulations that can amplify or reduce a signal) and scintillation (a higher frequency fluctuation in signal intensity). In an effort to elucidate the above issues a field test was conducted at the Naval Air Warfare Center (NAWC) at China Lake, CA, during July 2001. Transmission and scintillation measurements were made along slant, near-surface paths over land at 1280 m and 3850 m with a SSC (SPAWAR Systems Center) San Diego transmissometer that operated in the IR regime and in an almost aerosol-free environment. The field test has revealed that slow-scale refractive effects can create pronounced changes in the recorded one-minute average intensity of the IR source. Scintillation can also generate signal changes by a factor of 5 to 10 over very short time scales. In this paper we explore the relation between the refractive changes and scintillation, as well as models developed to describe and predict transmission and scintillation effects. Models include the exploitation of the propagation factor (a multiplicative factor defined from the local refractive field and geometry of the measuring system) and the use of wavelets as IR signal processors.

Tsintikidis, Dimitris; Doss-Hammel, Stephen M.

2003-03-01

390

Amplitude and phase scintillation measurements using the Global Positioning System  

NASA Astrophysics Data System (ADS)

The Global Positioning System (GPS) will ultimately include 18 to 24 satellites in 12-hour orbits, such that at least four satellites are simultaneously visible from any point on the earth. The satellites transmit a 10.23 MHz code with a period of exactly one week for precise time-of-arrival measurements. The system operates at L-band to minimize ionospheric effects. Nonetheless, an appropriately designed receiver can Doppler track and reconstruct the compressed carrier with adequate sensitivity to extract phase scintillation data. The phase data can be processed to predict the scintillation at lower frequencies where the perturbations are much more severe. Thus, the global coverage of the GPS system can be exploited for scintillation monitoring. A dual-frequency, Doppler-tracking GPS receiver with a specially designed interface for scintillation measurements has been developed. Preliminary results from operations at the Pacific and Atlantic equatorial stations are presented, and the potential of the GPS system for global scintillation monitoring is discussed.

Rino, C. L.; Cousins, M. D.; Klobuchar, J. A.

391

On the second order statistics for GPS ionospheric scintillation modeling  

NASA Astrophysics Data System (ADS)

ionospheric scintillation is a phenomenon that occurs frequently, typically during nighttime, affecting radio signals that propagate through the ionosphere. Depending on the temporal and spatial distribution, ionospheric scintillation can represent a problem in the availability and precision for the Global Navigation Satellite System's users. This work is concerned with the statistical evaluation of the amplitude ionospheric scintillation fading events, namely, level crossing rate (LCR) and average fading duration (AFD). Using ?-? model, the LCR and AFD are validated against experimental data obtained in So Jos dos Campos (23.1S; 45.8W; dip latitude 17.3S), Brazil, a station located near the southern crest of the ionospheric equatorial ionization anomaly. The amplitude scintillation data were collected between December 2001 and January 2002, a period of high solar flux conditions. The obtained results with the proposed model fitted quite well with the experimental data and performed better when compared to the widely used Nakagami-m model. Additionally, this work discusses the estimation of ? and ? parameters, and the best fading coefficients found in this analysis are related to scintillation severity. Finally, for theoretical situations in which no set of experimental data are available, this work also presents parameterized equations to describe these fading statistics properly.

Oliveira Moraes, Alison; Paula, Eurico Rodrigues; Assis Honorato Muella, Marcio Tadeu; Perrella, Waldecir Joo.

2014-02-01

392

Study of the Sensitivity of Plastic Scintillators 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 together, in series, in front of a deuterium-deuterium neutron generator, which produced fast neutrons of approximately 2.8MeV, in order to study the sensitivity of the plastic scintillators to fast neutrons. 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 reason for the investigation, in order to understand the sensitivity of the plastic scintillators to fast neutrons.

Abbott, David

2011-10-01

393

Miniature scintillating detector for small field radiation therapy.  

PubMed

In planning stereotactic radiosurgery treatments, depth dose curves, profiles, and dose rate of treatment beams are difficult to obtain with conventional detectors because of loss of lateral electronic equilibrium and volume averaging. A scintillating detector with high spatial resolution and good reliability has been developed to overcome this problem. The miniature dosimeter consists of two identical radiation-resistant 10 m long silica optical fibers, each connected to an independent silicon photodiode. A small cylindrical polystyrene scintillator (3.9 mm3) is optically glued to the detection fiber. The light seen by the photodiode connected to this fiber arises from fluorescence of the scintillator and from the Cerenkov effect produced in silica. The reference signal produced by the fiber without scintillator is used to subtract the Cerenkov light contribution from the raw detector response. The sensitive volume of the scintillating detector is nearly water-equivalent and thus minimizes dose distribution perturbation in water. The miniature dosimeter has a spatial resolution comparable to the film-densitometer system. Profiles of 1 cm diam, 6 MV photon beam measured with both systems show very similar shapes. Furthermore, the use of photodiodes instead of photomultiplier tubes gives a better stability response and offers the possibility to perform absolute dosimetry. PMID:10619239

Ltourneau, D; Pouliot, J; Roy, R

1999-12-01

394

Plastic scintillators: a powerful tool to reduce mixed waste  

SciTech Connect

Wastes containing radioactive and organic compounds (mixed wastes) are difficult to dispose because of the regulations established for nuclear and hazardous wastes. Mixed wastes originate mainly in the emulsions generated in beta emitter determinations by Liquid Scintillation techniques. The use of plastic scintillators instead of liquid cocktails may facilitate the segregation, after measurement, of sample and scintillator without introducing additional wastes in the measurement step. In this study, we compare the capability of Plastic Scintillation (PS) versus Liquid Scintillation (LS) and Cerenkov (C) techniques to determine beta emitters in routine measurements. Results obtained show that high and medium energy beta emitters (Sr-90/Y-90 and C-14) can be quantified in aqueous samples by using PS with similar relative errors (< 5%) as those obtained by LS or C, for any activity level considered. For low energy emitters (H-3), best results using PS are achieved for medium activity levels. Additionally, measurements performed in solutions including alpha (Pu-238) and beta-gamma (Cs-134) emitters confirm the capability of PS to extent the application of this technique to the determination of these types of isotopes. (authors)

Tarancon, A.; Bagan, H.; Garcia, J.F.; Rauret, G. [Departament de Quimica Analitica. Facultat de Quimica. Universitat de Barcelona (Spain)

2008-07-01

395

Screening in Pregnancy  

PubMed Central

Over the past 20 years, traditional elements of antenatal care have been supplemented by complex biochemical and biophysical investigations. With his/her knowledge of the patient and awareness of the principles of screening, the family physician is ideally placed to assess potential problems in pregnancy. This article reviews the rationale for screening for certain disorders in pregnancy. Genetic disorders, infectious diseases, and other specific conditions are considered. Some of the more recent controversies in prenatal screening are highlighted. PMID:21253226

Biringer, Anne

1988-01-01

396

ScreenFlow  

NSDL National Science Digital Library

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

2008-01-01

397

Opportunities to improve colorectal and breast cancer screening in Connecticut.  

PubMed

Colorectal and breast cancer represent serious and common public-health problems in the United States. While effective screening tests exist for both types of cancer, Connecticut lacks a consistent source of data about screening rates to guide improvement efforts. Beginning in 2011, the Connecticut Department of Public Health commissioned Qualidigm, the state's Medicare Quality Improvement Organization, to conduct an analysis of the most recent fee-for-service Medicare claims data to determine screening rates for colorectal cancer (2000-2009) and breast cancer (2008-2009). This article highlights key findings of this analysis in order to increase awareness of opportunities for improvement in colorectal and breast cancer screening. The article also offers recommendations about next steps that primary care clinicians can consider to improve cancer screening among their patient populations. PMID:23427366

Van Hoof, Thomas J; Ho, Shih-Yieh; Kelvey-Albert, Michele; Wright, Ches Donette; Meehan, Thomas P

2013-01-01

398

AMG All Music Guide  

NSDL National Science Digital Library

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

399

Screening for Heart Murmurs. What's Normal and What's Not.  

ERIC Educational Resources Information Center

A step-by-step guide to auscultating young athletes helps physicians identify normal heart murmurs as well as sounds that might signify underlying cardiac pathology. Rapid, thorough preparticipation screening can help differentiate athletes who may require treatment or activity restriction from those with normal murmurs who can remain active. (SM)

Pflieger, Kurt L.; Strong, William B.

1992-01-01

400

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

SciTech Connect

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

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

2012-02-15

401

Silicon Photomultiplier Choice for the Scintillating Fiber Tracker in Second Generation Proton Computed Tomography Scanner.  

National Technical Information Service (NTIS)

Scintillating fibers are capable of charged particle tracking with high position resolution, as demonstrated by the central fiber tracker of the D0 experiment. The charged particles will deposit less energy in the polystyrene scintillating fibers as oppos...

A. Gearhart, A. Ronzhin, E. Johnson, P. Rubinov, V. Medvedev, V. Rykalin, V. Sleptcov

2012-01-01

402

Development of Scintillating Bolometers for Dark Matter Searches  

NASA Astrophysics Data System (ADS)

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

Martnez, M.; Cuesta, C.; Garca, E.; Ginestra, C.; de Solrzano, A. Ortiz; Ortigoza, Y.; Pobes, C.; Puimedn, J.; Roln, T.; Sarsa, M. L.; Villar, J. A.; Coron, N.; Gironnet, J.; Leblanc, J.; de Marcillac, P.; Redon, T.; Torres, L.; Veber, P.; Velzquez, M.

403

Hadronic Shower Development in Iron-Scintillator Tile Calorimetry  

E-print Network

The lateral and longitudinal profiles of hadronic showers detected by a prototype of the ATLAS Iron-Scintillator Tile Hadron Calorimeter have been investigated. This calorimeter uses a unique longitudinal configuration of scintillator tiles. Using a fine-grained pion beam scan at 100 GeV, a detailed picture of transverse shower behavior is obtained. The underlying radial energy densities for four depth segments and for the entire calorimeter have been reconstructed. A three-dimensional hadronic shower parametrization has been developed. The results presented here are useful for understanding the performance of iron-scintillator calorimeters, for developing fast simulations of hadronic showers, for many calorimetry problems requiring the integration of a shower energy deposition in a volume and for future calorimeter design.

Tilecal Atlas Collaboration

1999-04-29

404

Hadronic Shower Development in Tile Iron-Scintillator Calorimetry  

E-print Network

The lateral and longitudinal profiles of hadronic showers detected by a prototype of the ATLAS Iron-Scintillator Tile Hadron Calorimeter have been investigated. This calorimeter uses a unique longitudinal configuration of scintillator tiles. Using a fine-grained pion beam scan at 100 GeV, a detailed picture of transverse shower behavior is obtained. The underlying radial energy densities for four depth segments and for the entire calorimeter have been reconstructed. A three-dimensional hadronic shower parametrization has been developed. The results presented here are useful for understanding the performance of iron-scintillator calorimeters, for developing fast simulations of hadronic showers, for many calorimetry problems requiring the integration of a shower energy deposition in a volume and for future calorimeter design.

Yuri A. Kulchitsky

1999-10-07

405

Hadronic shower development in Iron-Scintillator Tile Calorimetry  

NASA Astrophysics Data System (ADS)

The lateral and longitudinal profiles of hadronic showers detected by a prototype of the ATLAS Iron-Scintillator Tile Hadron Calorimeter have been investigated. This calorimeter presents a unique longitudinal configuration of scintillator tiles. Using a fine-grained pion beam scan at 100 GeV, a detailed picture of transverse shower behaviour is obtained. The underlying radial energy densities for the four depth segments and for the entire calorimeter have been reconstructed. A three-dimensional hadronic shower parametrisation has been developed. The results presented here are useful for understanding the performance of iron-scintillator calorimeters, for developing fast simulations of hadronic showers, for many calorimetry problems requiring the integration of a shower energy deposition in a volume and for future calorimeters design.

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

2000-03-01

406

Scintillation Properties of Eu2+-Activated Barium Fluoroiodide  

SciTech Connect

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

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

2009-11-18

407

Working with some of the newer high-Z scintillators  

SciTech Connect

We have performed simple laboratory studies of several of the newer high-Z inorganic scintillators, with a primary goal of evaluating their relative merits as sensors for space-borne instruments. It is appropriate to consider using one of these materials when light output can be exchanged for some other beneficial property, such as higher stopping power (bismuth germanate), superior resistance to radiation damage (barium fluoride), or fast decay time (barium fluoride and pure cesium iodide). Our work has revealed or confirmed important characteristics -- both favorable and unfavorable -- of these newer scintillators. For example, the temperature dependence and particle species dependence of the fast and slow scintillation output of barium fluoride and pure cesium iodide will be described. 6 refs.

Laros, J.G.

1989-01-01

408

Scintillator-fiber charged particle track-imaging detector  

NASA Technical Reports Server (NTRS)

A scintillator-fiber charged-particle track-imaging detector was developed using a bundle of square cross section plastic scintillator fiber optics, proximity focused onto an image intensified charge injection device (CID) camera. The tracks of charged particle penetrating into the scintillator fiber bundle are projected onto the CID camera and the imaging information is read out in video format. The detector was exposed to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei and images of their tracks were obtained. Details of the detector technique, properties of the tracks obtained, and preliminary range measurements of 15 MeV protons stopping in the fiber bundle are presented.

Binns, W. R.; Israel, M. H.; Klarmann, J.

1983-01-01

409

Water equivalent plastic scintillation detectors in radiation therapy.  

PubMed

A review of the dosimetric characteristics and properties of plastic scintillation detectors for use in radiation therapy is presented. The detectors show many desirable qualities when exposed to megavoltage photon and electron beams, including water equivalence, energy independence, reproducibility, dose linearity, resistance to radiation damage and near temperature independence. These detectors do not require the usual conversion and/or correction factors used to convert the readings from common dosemeters to absorbed dose. Due to their small detecting volume, plastic scintillation detectors exhibit excellent spatial resolution. Detector performance, in certain specific cases, can be affected by radiation-induced light arising in the optical fibres that carry the scintillator signal to a photodetector. While this effect is negligible for photon beams, it may not be ignored for electron beams and needs to be accounted for. PMID:16882685

Beddar, A S

2006-01-01

410

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

SciTech Connect

We have constructed lead scintillator sandwich calorimeters with 1/4 [chi][sub o] sampling frequency and total thickness [approximately]16[chi][sub o]. The 4 mm thick scintillator plates are read out by wavelength shifter fibers 1 mm in diameter which pass through holes penetrating the plates on a .95 cm [times] .95 cm grid (Shish-Kebab geometry). We tested these modules in the A2 test beam at Brookhaven using low energy electrons and hadrons. Results are here presented on electron energy and time-of-flight resolution obtained with various combinations of scintillators and wavelength shifters. We also describe results on e/[pi] separation obtained with a new technique for the longitudinal segmentation.

Kistenev, E.; White, S. (Brookhaven National Lab., Upton, NY (United States)); Pischalnikov, Y.; Protopopov, Y.; Rykalin, V. (Institut Fiziki Vysokikh Ehnergij, Protvino (Russian Federation))

1992-01-01

411

Timing resolution of ``Shisk-Kebab`` lead scintillator sandwich calorimeters  

SciTech Connect

We have constructed lead scintillator sandwich calorimeters with 1/4 {chi}{sub o} sampling frequency and total thickness {approximately}16{chi}{sub o}. The 4 mm thick scintillator plates are read out by wavelength shifter fibers 1 mm in diameter which pass through holes penetrating the plates on a .95 cm {times} .95 cm grid (Shish-Kebab geometry). We tested these modules in the A2 test beam at Brookhaven using low energy electrons and hadrons. Results are here presented on electron energy and time-of-flight resolution obtained with various combinations of scintillators and wavelength shifters. We also describe results on e/{pi} separation obtained with a new technique for the longitudinal segmentation.

Kistenev, E.; White, S. [Brookhaven National Lab., Upton, NY (United States); Pischalnikov, Y.; Protopopov, Y.; Rykalin, V. [Institut Fiziki Vysokikh Ehnergij, Protvino (Russian Federation)

1992-12-31

412

Scintillation Response of Liquid Xenon to Low Energy Nuclear Recoils  

E-print Network

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

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

2005-03-29

413

Stellar scintillations as a remote atmospheric wave-front sensor.  

PubMed

Stellar scintillations are considered noise in adaptive-optics sensors and are measured for calibration purposes only. We propose to use scintillations to provide direct instantaneous information about the structure of the atmosphere. As a result it will be possible to increase the field of view provided by adaptive optics. The scintillation pattern is created when stellar light is diffracted by high-altitude turbulence. Alternatively, this pattern can be viewed as a Laplacian of this turbulence and can thus be inverted to estimate it. The measurement is limited by the intensity and the angular size of the reference star, by the height distribution of the atmospheric turbulence, and by the detector resolution and spectral response. PMID:19865430

Ribak, E N; Gershnik, E; Cheselka, M

1996-03-15

414

Gasolines as primary solvents in liquid scintillation counting  

SciTech Connect

Gasolines from several commercial sources have been used as primary solvents in liquid scintillation counting of dry and aqueous samples of either /sup 3/H- or /sup 14/C-labeled compounds. Dry samples can be counted only by the addition of fluors to the gasolines, and compared to a standard liquid scintillator, efficiencies of around 75% were attained. For the counting of aqueous samples, gasolines must also be supplemented with secondary solvents (i.e., 10% naphthalene, 5% Triton X-100, or 10% methanol). Simply with Triton X-100, efficiencies similar to those obtained with a dioxane-based liquid scintillator were observed in the case of some gasolines. Drawbacks to gasoline are the higher toxicity and the variation of efficiency, probably depending on the presence of color markers. On the positive side is the low price of the gasolines, compared with either toluene or dioxane, and the facility of purchasing.

Fernandez, A.; Ma Pinto, R.; Sillero, A.

1986-11-01

415

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

ERIC Educational Resources Information Center

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

Kaopua, Lana Sue

2008-01-01

416

Final Report on Actinide Glass Scintillators for Fast Neutron Detection  

SciTech Connect

This is the final report of an experimental investigation of actinide glass scintillators for fast-neutron detection. It covers work performed during FY2012. This supplements a previous report, PNNL-20854 Initial Characterization of Thorium-loaded Glasses for Fast Neutron Detection (October 2011). The work in FY2012 was done with funding remaining from FY2011. As noted in PNNL-20854, the glasses tested prior to July 2011 were erroneously identified as scintillators. The decision was then made to start from scratch with a literature survey and some test melts with a non-radioactive glass composition that could later be fabricated with select actinides, most likely thorium. The normal stand-in for thorium in radioactive waste glasses is cerium in the same oxidation state. Since cerium in the 3+ state is used as the light emitter in many scintillating glasses, the next most common substitute was used: hafnium. Three hafnium glasses were melted. Two melts were colored amber and a third was clear. It barely scintillated when exposed to alpha particles. The uses and applications for a scintillating fast neutron detector are important enough that the search for such a material should not be totally abandoned. This current effort focused on actinides that have very high neutron capture energy releases but low neutron capture cross sections. This results in very long counting times and poor signal to noise when working with sealed sources. These materials are best for high flux applications and access to neutron generators or reactors would enable better test scenarios. The total energy of the neutron capture reaction is not the only factor to focus on in isotope selection. Many neutron capture reactions result in energetic gamma rays that require large volumes or high densities to detect. If the scintillator is to separate neutrons from gamma rays, the capture reactions should produce heavy particles and few gamma rays. This would improve the detection of a signal for fast neutron capture.

Bliss, Mary; Stave, Jean A.

2012-10-01

417

A fluorocarbon plastic scintillator for neutron detection: Proof of concept  

NASA Astrophysics Data System (ADS)

The fast neutron nuclear reactions, such as 19F(n, ?)16N and 19F(n, p)19O, can be used to detect highly energetic neutrons due to their energy thresholds above which these activation reactions can occur. This was recently shown (Gozani et al., 2011 [2]) as a means to detect concealed nuclear materials via the detection of the high energy (?3 MeV) prompt neutrons emitted during the photofission process. Fluorine-loaded scintillation detectors, such as inorganic BaF2 and CaF2, and non-hydrogenous fluorocarbon (FC) liquid scintillators, such as Saint-Gobain BC-509 and Eljen Technology EJ-313, are possible candidates. The latter was selected and implemented in the above mentioned reference. In our paper, we propose a new pentafluorostyrene-based plastic scintillator (F-plastic) which can be a good alternative to the abovementioned scintillators. The fluorine content of F-plastic is equal to 3.731022 atoms/cm3, and the F/H ratio is 1.66. The fluorescence and radioluminescence spectra of the F-plastic display an emission maximum centered approximately at 420 nm. The light output measured for gamma rays is 3100300 photons/MeV, which is approximately 30% of the light output of the standard EJ-200 plastic scintillator and is similar to EJ-313. The response of the F-plastic to neutrons and gamma rays is presented and compared to the EJ-200 scintillator. Additionally, the n/? pulse shape discrimination (PSD) was measured and showed improvement of the discrimination at neutron energies as high as 3 MeV.

Hamel, Matthieu; Sibczynski, Pawel; Blanc, Pauline; Iwanowska, Joanna; Carrel, Frdrick; Syntfeld-Ka?uch, Agnieszka; Normand, Stphane

2014-12-01

418

Smaller, Lower-Power Fast-Neutron Scintillation Detectors  

NASA Technical Reports Server (NTRS)

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

Patel, Jagdish; Blaes, Brent

2008-01-01

419

Flux tube analysis of L-band ionospheric scintillation  

NASA Astrophysics Data System (ADS)

This manuscript presents magnetic flux tube analysis of L-band signal scintillation in the nighttime equatorial and low-latitude ionosphere. Residues of the scintillation index S4 estimated from the L-band signals received from Geostationary Earth Orbit (GEO) satellites are employed in the analysis. The S4 estimates have been shown to be associated with simultaneous GPS VTEC variations derived from JPL's GIPSY-GIM package. We have applied the wavelet decomposition technique simultaneously on the S4 time series in a flux tube over the equatorial and low-latitude regions. The technique decomposes the S4 signal to identify the dominant mode of variabilities and the temporal variations of scintillation-producing irregularities in the context of a flux tube. Statistically significant regions of the wavelet power spectra considered in our study have mainly shown that (a) dominant plasma irregularities associated with S4 variabilities in a flux tube have periods of about 4 to 15 minutes (horizontal irregularity scales of about 24 to 90 km). These periods match short period gravity waves, (b) scintillation-producing irregularities are anisotropic along the flux tube and in the east-west direction, and (c) the occurrences of scintillation-producing irregularities along the flux tube indicate that the entire flux tube became unstable. However, plasma instability occurrences were not simultaneous in most cases along the flux tube, there were time delays of various orders. Understanding the attributes of L-band scintillation-producing irregularities could be important for developing measures to mitigate L-band signal degradation.

Shume, E. B.; Mannucci, A. J.; Butala, M. D.; Pi, X.; Valladares, C. E.

2013-06-01

420

Quenching correction for volumetric scintillation dosimetry of proton beams  

PubMed Central

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

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

2013-01-01

421

Quenching correction for volumetric scintillation dosimetry of proton beams  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

422

Recent developments in scintillating fiber detection systems in radiation therapy  

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

423

Quenching correction for volumetric scintillation dosimetry of proton beams.  

PubMed

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

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

2013-01-21

424

A Unified Low-Elevation-Angle Scintillation Model  

NASA Astrophysics Data System (ADS)

Enabling communications at very low elevation angles can lengthen the duration of a tracking pass between a satellite and a ground station, which in turn can increase the amount of data return and possibly reduce the number of required supporting ground station tracking passes. Link performance, especially at very low angles and high frequencies, depends heavily on terrain, atmosphere, and weather conditions. Among the different contributions to attenuation, scintillation fading plays a very significant role and can impair the performance of the link. It is therefore necessary to accurately model the overall impact to the link due to scintillation fading. The current International Telecommunication Union ITU-R P.618-10 Recommendation describes three scintillation loss models as a function of elevation angle and percentage of time for which the loss exceeds a certain threshold. Implementation of the recommendation resulted in the uncovering of several issues. Particularly, it was identified that (i) iterative solutions to an implicit nonlinear exponential model, in some cases, are not guaranteed to exist, (ii) there is a discontinuity in fading values between models at the cross-over elevation angle, (iii) at certain low elevation angles scintillation from the shallow fade model generates unrealistically small losses, and (iv) for elevation angles lying between 4 and 5 deg, there are two applicable scintillation models that yield conflicting values. In this article, we develop a new approach to unify the different fading models within the current ITU recommendation and fully remove the discrepancies. We further validated our models with ITU-adopted scintillation data measured at Goonhilly, Great Britain, and data from several recent NASA Space Shuttle launches. This improved model was provisionally approved at the ITU International Meeting in Italy, November 2010, and is being evaluated by the ITU members for adoption into the next-version ITU Recommendation.

Lee, C. H.; Cheung, K.-M.; Ho, C.

2011-05-01

425

Production of a gadolinium-loaded liquid scintillator for the Daya Bay reactor neutrino experiment  

NASA Astrophysics Data System (ADS)

We report on the production and characterization of liquid scintillators for the detection of electron antineutrinos by the Daya Bay reactor neutrino experiment. A 185 tons of gadolinium-loaded (0.1% by mass) liquid scintillator (Gd-LS) and a 200 tons of unloaded liquid scintillator (LS) were successfully produced from a linear-alkylbenzene (LAB) solvent in 6 months. The scintillator properties, the production and purification systems, and the quality assurance and control (QA/QC) procedures are described.

Beriguete, Wanda; Cao, Jun; Ding, Yayun; Hans, Sunej; Heeger, Karsten M.; Hu, Liangming; Huang, Aizhong; Luk, Kam-Biu; Nemchenok, Igor; Qi, Ming; Rosero, Richard; Sun, Hansheng; Wang, Ruiguang; Wang, Yifang; Wen, Liangjian; Yang, Yi; Yeh, Minfang; Zhang, Zhiyong; Zhou, Li

2014-11-01

426

Scintillation spectra of stars and planets and dependence of their characteristics on meteorological conditions  

NASA Technical Reports Server (NTRS)

Scintillation spectra of stars and planets were obtained at Goloseyevo. The dependence was studied of the scintillation spectral density and of the amplitude and frequency characteristics on zenith distances and aerological parameters. The differences in the scintillation spectra amplitude characteristics for white and red stars were found. The increase in the limiting frequency of the planet scintillation spectrum (as the wind becomes stronger) was studied along with the dependence of spectral characteristics on wind and star azimuth differences.

Filippov, Y. K.

1974-01-01

427

Polystyrene-based scintillator with pulse-shape discrimination capability  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

428

Methods of alleviation of ionospheric scintillation effects on digital communications  

NASA Technical Reports Server (NTRS)

The degradation of the performance of digital communication systems because of ionospheric scintillation effects can be reduced either by diversity techniques or by coding. The effectiveness of traditional space-diversity, frequency-diversity and time-diversity techniques is reviewed and design considerations isolated. Time-diversity signaling is then treated as an extremely simple form of coding. More advanced coding methods, such as diffuse threshold decoding and burst-trapping decoding, which appear attractive in combatting scintillation effects are discussed and design considerations noted. Finally, adaptive coding techniques appropriate when the general state of the channel is known are discussed.

Massey, J. L.

1974-01-01

429

A decametric wavelength radio telescope for interplanetary scintillation observations  

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

430

Silica scintillating materials prepared by sol-gel methods  

SciTech Connect

Silica was investigated as a rad-hard alternative to organic polymer hosts for organic scintillators. Silica sol-gels were prepared by hydrolysis of tetramethoxysilane in alcohol solutions. organic dyes were incorporated into the gels by dissolving in methanol at the sol stage of gel formation. The silica sol-gel matrix is very rad-hard. The radiation stability of silica scintillators prepared by this method is dye-limited. Transient radioluminescence was measured following excitation with 30 ps pulses of 20 MeV electrons.

Werst, D.W.; Sauer, M.C. Jr.; Cromack, K.R.; Lin, Y.; Tartakovsky, E.A.; Trifunac, A.D.

1993-12-31

431

Single-photoelectron noise reduction in scintillation detectors  

SciTech Connect

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

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

1995-10-01

432

Properties of an imaging gas scintillation proportional counter  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

433

Radiographic intensifying screen  

SciTech Connect

A radiographic intensifying screen comprising a substrate and a fluorescent layer provided thereon and consisting essentially of a binder and a radioluminescent phosphor dispersed therein. The binder comprises linear polyester resin or linear polyester resin crosslinked with a crosslinking agent. The screen exhibits improved physical properties.

Ochiai, T.

1985-02-26

434

Sintered metal sand screen  

SciTech Connect

This patent describes a well screen fo