Sample records for gamma spectroscopy measurements

  1. Gamma-ray spectroscopy measurements and simulations for uranium mining

    NASA Astrophysics Data System (ADS)

    Marchais, T.; Pérot, B.; Carasco, C.; Allinei, P.-G.; Chaussonnet, P.; Ma, J.-L.; Toubon, H.

    2018-01-01

    AREVA Mines and the Nuclear Measurement Laboratory of CEA Cadarache are collaborating to improve the sensitivity and precision of uranium concentration evaluation by means of gamma measurements. This paper reports gamma-ray spectra, recorded with a high-purity coaxial germanium detector, on standard cement blocks with increasing uranium content, and the corresponding MCNP simulations. The detailed MCNP model of the detector and experimental setup has been validated by calculation vs. experiment comparisons. An optimization of the detector MCNP model is presented in this paper, as well as a comparison of different nuclear data libraries to explain missing or exceeding peaks in the simulation. Energy shifts observed between the fluorescence X-rays produced by MCNP and atomic data are also investigated. The qualified numerical model will be used in further studies to develop new gamma spectroscopy approaches aiming at reducing acquisition times, especially for ore samples with low uranium content.

  2. Nuclear Forensics using Gamma-ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Norman, E. B.

    2016-09-01

    Much of George Dracoulis's research career was devoted to utilising gamma-ray spectroscopy in fundamental studies in nuclear physics. This same technology is useful in a wide range of applications in the area of nuclear forensics. Over the last several years, our research group has made use of both high- and low-resolution gamma-ray spectrometers to: identify the first sample of plutonium large enough to be weighed; determine the yield of the Trinity nuclear explosion; measure fission fragment yields as a function of target nucleus and neutron energy; and observe fallout in the U. S. from the Fukushima nuclear reactor accident.

  3. Gamma ray spectroscopy in astrophysics. [conferences

    NASA Technical Reports Server (NTRS)

    Cline, T. L. (Editor); Ramaty, R. (Editor)

    1978-01-01

    Experimental and theoretical aspects of gamma ray spectroscopy in high energy astrophysics are discussed. Line spectra from solar, stellar, planetary, and cosmic gamma rays are examined as well as HEAO investigations, the prospects of a gamma ray observatory, and follow-on X-ray experiments in space.

  4. Experimental review of light quark spectroscopy from e/sup +/e/sup -/ production and. gamma gamma. collisions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Toki, W.H.

    1987-07-01

    This is an experimental review of light quark spectroscopy from e/sup +/e/sup -/ production and ..gamma gamma.. collision results presented at the 2nd International Conference on Hadron Spectroscopy at KEK, Japan. The recent results in ..gamma gamma.. production have evidence for the J/sup PC/ = 1/sup + +/, E/f/sub 1/(1420) and D/f/sub 1/(1285), mesons from the TPC and Mark II collaborations and upper limits for pseudoscalar resonances from the Crystal Ball collaboration. The results in J/psi reactions include D/f/sub 1/(1285) meson production in radiative decays and a complete measurement of the hadronic decays into pseudoscalar-vector pairs from the DM2 collaborationmore » and evidence for phi phi production in radiative decays and a study of the iota line shape from the Mark III collaboration. A short review of simple theoretical ideas is presented.« less

  5. Gamma ray spectroscopy monitoring method and apparatus

    DOEpatents

    Stagg, William R; Policke, Timothy A

    2017-05-16

    The present invention relates generally to the field of gamma ray spectroscopy monitoring and a system for accomplishing same to monitor one or more aspects of various isotope production processes. In one embodiment, the present invention relates to a monitoring system, and method of utilizing same, for monitoring one or more aspects of an isotope production process where the monitoring system comprises: (A) at least one sample cell; (B) at least one measuring port; (C) at least one adjustable collimator device; (D) at least one shutter; and (E) at least one high resolution gamma ray spectrometer.

  6. Simultaneous beta and gamma spectroscopy

    DOEpatents

    Farsoni, Abdollah T.; Hamby, David M.

    2010-03-23

    A phoswich radiation detector for simultaneous spectroscopy of beta rays and gamma rays includes three scintillators with different decay time characteristics. Two of the three scintillators are used for beta detection and the third scintillator is used for gamma detection. A pulse induced by an interaction of radiation with the detector is digitally analyzed to classify the type of event as beta, gamma, or unknown. A pulse is classified as a beta event if the pulse originated from just the first scintillator alone or from just the first and the second scintillator. A pulse from just the third scintillator is recorded as gamma event. Other pulses are rejected as unknown events.

  7. The goals of gamma-ray spectroscopy in high energy astrophysics

    NASA Technical Reports Server (NTRS)

    Lingenfelter, Richard E.; Higdon, James C.; Leventhal, Marvin; Ramaty, Reuven; Woosley, Stanford E.

    1990-01-01

    The use of high resolution gamma-ray spectroscopy in astrophysics is discussed with specific attention given to the application of the Nuclear Astrophysics Explorer (NAE). The gamma-ray lines from nuclear transitions in radionucleic decay and positron annihilation permits the study of current sites, rates and models of nucleosynthesis, and galactic structure. Diffuse galactic emission is discussed, and the high-resolution observations of gamma-ray lines from discrete sites are also described. Interstellar mixing and elemental abundances can also be inferred from high-resolution gamma-ray spectroscopy of nucleosynthetic products. Compact objects can also be examined by means of gamma-ray emissions, allowing better understanding of neutron stars and the accreting black hole near the galactic center. Solar physics can also be investigated by examining such features as solar-flare particle acceleration and atmospheric abundances.

  8. Elemental analysis using natural gamma-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Aksoy, A.; Naqvi, A. A.; Khiari, F. Z.; Abujarad, F.; Al-Ohali, M.; Sumani, M.

    1994-12-01

    A gamma-ray spectroscopy setup has been recently established to measure the natural gamma-ray activity from potassium ( 40K), uranium ( 238U), and thorium ( 232Th) isotopes in rock samples of oil well-logs. The setup mainly consists of a shielded 135 cm 3 Hyper Pure Germanium (HPGe) detector, a 5 in. × 5 in. NaT(Tl) detector and a PC based data acquisition system. The core samples, with 70-100 g weight, have cylindrical geometry and are sealed such that radon gas from 238U decay would not escape from the sample. For room background subtraction, pure quartz samples identical to core samples were used. The sample is first counted with the HPGe detector to identify the elements through its characteristics gamma rays. Then the elemental concentration is determined by counting the sample with a NaI detector. In order to determine the absolute concentrations, the sample activity is compared with the activities of standards supplied by NIST and IAEA. The concentration of 238U and 232Th has been determined in ppm range with that of 40K in wt.%.

  9. Quantification of 235U and 238U activity concentrations for undeclared nuclear materials by a digital gamma-gamma coincidence spectroscopy.

    PubMed

    Zhang, Weihua; Yi, Jing; Mekarski, Pawel; Ungar, Kurt; Hauck, Barry; Kramer, Gary H

    2011-06-01

    The purpose of this study is to investigate the possibility of verifying depleted uranium (DU), natural uranium (NU), low enriched uranium (LEU) and high enriched uranium (HEU) by a developed digital gamma-gamma coincidence spectroscopy. The spectroscopy consists of two NaI(Tl) scintillators and XIA LLC Digital Gamma Finder (DGF)/Pixie-4 software and card package. The results demonstrate that the spectroscopy provides an effective method of (235)U and (238)U quantification based on the count rate of their gamma-gamma coincidence counting signatures. The main advantages of this approach over the conventional gamma spectrometry include the facts of low background continuum near coincident signatures of (235)U and (238)U, less interference from other radionuclides by the gamma-gamma coincidence counting, and region-of-interest (ROI) imagine analysis for uranium enrichment determination. Compared to conventional gamma spectrometry, the method offers additional advantage of requiring minimal calibrations for (235)U and (238)U quantification at different sample geometries. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  10. Recoil Distance Method lifetime measurements via gamma-ray and charged-particle spectroscopy at NSCL

    NASA Astrophysics Data System (ADS)

    Voss, Philip Jonathan

    The Recoil Distance Method (RDM) is a well-established technique for measuring lifetimes of electromagnetic transitions. Transition matrix elements derived from the lifetimes provide valuable insight into nuclear structure. Recent RDM investigations at NSCL present a powerful new model-independent tool for the spectroscopy of nuclei with extreme proton-to-neutron ratios that exhibit surprising behavior. Neutron-rich 18C is one such example, where a small B(E2; 2+1 → 0+gs) represented a dramatic shift from the expected inverse relationship between the B(E2) and 2+1 excitation energy. To shed light on the nature of this quadrupole excitation, the RDM lifetime technique was applied with the Koln/NSCL plunger. States in 18C were populated by the one-proton knockout reaction of a 19N secondary beam. De-excitation gamma rays were detected with the Segmented Germanium Array in coincidence with reaction residues at the focal plane of the S800 Magnetic Spectrometer. The deduced B(E2) and excitation energy were both well described by ab initio no-core shell model calculations. In addition, a novel extension of RDM lifetime measurements via charged-particle spectroscopy of exotic proton emitters has been investigated. Substituting the reaction residue degrader of the Koln/NSCL plunger with a thin silicon detector permits the study of short-lived nuclei beyond the proton dripline. A proof of concept measurement of the mean lifetime of the two-proton emitter 19Mg was conducted. The results indicated a sub-picosecond lifetime, one order of magnitude smaller than the published results, and validate this new technique for lifetime measurements of charged-particle emitters.

  11. Gamma ray spectroscopy with Arduino UNO

    NASA Astrophysics Data System (ADS)

    Lavelle, C. M.

    2018-05-01

    We review a simple gamma ray spectrometer constructed on a solderless breadboard. The spectrometer's detector consists of a CsI(Tl) scintillator and silicon photomultiplier (SiPM) and its readout is facilitated by an Arduino UNO. The system is low cost and utilizes a minimum of components while still achieving satisfactory charge linearity and noise levels. This instrument can be used in instructional laboratories to introduce both radiation detection and analog signal processing concepts. We also expect it will be of interest to those seeking to introduce gamma spectroscopy to the expanding ecosystem of Arduino hardware.

  12. First On-Site True Gamma-Ray Imaging-Spectroscopy of Contamination near Fukushima Plant

    PubMed Central

    Tomono, Dai; Mizumoto, Tetsuya; Takada, Atsushi; Komura, Shotaro; Matsuoka, Yoshihiro; Mizumura, Yoshitaka; Oda, Makoto; Tanimori, Toru

    2017-01-01

    We have developed an Electron Tracking Compton Camera (ETCC), which provides a well-defined Point Spread Function (PSF) by reconstructing a direction of each gamma as a point and realizes simultaneous measurement of brightness and spectrum of MeV gamma-rays for the first time. Here, we present the results of our on-site pilot gamma-imaging-spectroscopy with ETCC at three contaminated locations in the vicinity of the Fukushima Daiichi Nuclear Power Plants in Japan in 2014. The obtained distribution of brightness (or emissivity) with remote-sensing observations is unambiguously converted into the dose distribution. We confirm that the dose distribution is consistent with the one taken by conventional mapping measurements with a dosimeter physically placed at each grid point. Furthermore, its imaging spectroscopy, boosted by Compton-edge-free spectra, reveals complex radioactive features in a quantitative manner around each individual target point in the background-dominated environment. Notably, we successfully identify a “micro hot spot” of residual caesium contamination even in an already decontaminated area. These results show that the ETCC performs exactly as the geometrical optics predicts, demonstrates its versatility in the field radiation measurement, and reveals potentials for application in many fields, including the nuclear industry, medical field, and astronomy. PMID:28155883

  13. Positron Annihilation Induced Auger and Gamma Spectroscopy of Catalytically Important Surfaces

    NASA Astrophysics Data System (ADS)

    Weiss, A. H.; Nadesalingam, M. P.; Sundaramoorthy, R.; Mukherjee, S.; Fazleev, N. G.

    2006-10-01

    The annihilation of positrons with core electrons results in unique signatures in the spectra of Auger-electron and annihilation-gamma rays that can be used to make clear chemical identification of atoms at the surface. Because positrons implanted at low energies are trapped with high efficiency in the image-correlation well where they are localized just outside the surface it is possible to use annihilation induced Auger and Gamma signals to probe the surfaces of solids with single atomic layer depth resolution. In this talk we will report recent applications of Positron Annihilation Induced Auger Electron Spectroscopy (PAES) and Auger-Gamma Coincidence Spectroscopy (AGCS) to the study of surface structure and surface chemistry. Our research has demonstrated that PAES spectra can provide new information regarding the composition of the top-most atomic layer. Applications of PAES to the study of catalytically important surfaces of oxides and wide band-gap semiconductors including TiO2, SiO2,Cu2O, and SiC will be presented. We conclude with a discussion of the use of Auger-Gamma and Gamma-Gamma coincidence spectroscopy for the study of surfaces at pressures closer to those found in practical chemical reactors. Research supported by the Welch Foundation Grant Number Y-1100.

  14. Photon-induced positron annihilation lifetime spectroscopy using ultrashort laser-Compton-scattered gamma-ray pulses

    NASA Astrophysics Data System (ADS)

    Taira, Y.; Toyokawa, H.; Kuroda, R.; Yamamoto, N.; Adachi, M.; Tanaka, S.; Katoh, M.

    2013-05-01

    High-energy ultrashort gamma-ray pulses can be generated via laser Compton scattering with 90° collisions at the UVSOR-II electron storage ring. As an applied study of ultrashort gamma-ray pulses, a new photon-induced positron annihilation lifetime spectroscopy approach has been developed. Ultrashort gamma-ray pulses with a maximum energy of 6.6 MeV and pulse width of 2.2 ps created positrons throughout bulk lead via pair production. Annihilation gamma rays were detected by a BaF2 scintillator mounted on a photomultiplier tube. A positron lifetime spectrum was obtained by measuring the time difference between the RF frequency of the electron storage ring and the detection time of the annihilation gamma rays. We calculated the response of the BaF2 scintillator and the time jitter caused by the variation in the total path length of the ultrashort gamma-ray pulses, annihilation gamma rays, and scintillation light using a Monte Carlo simulation code. The positron lifetime for bulk lead was successfully measured.

  15. Solar X-Ray and Gamma-Ray Imaging Spectroscopy

    NASA Astrophysics Data System (ADS)

    Dennis, B. R.; Christe, S. D.; Shih, A. Y.; Holman, G. D.; Emslie, A. G.; Caspi, A.

    2018-02-01

    X-ray and gamma-ray Sun observations from a lunar-based observatory would provide unique information on solar atmosphere thermal and nonthermal processes. EUV and energetic neutral atom imaging spectroscopy would augment the scientific value.

  16. Delayed Gamma-Ray Spectroscopy for Non-Destructive Assay of Nuclear Materials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ludewigt, Bernhard; Mozin, Vladimir; Campbell, Luke

    2015-06-01

    High-­energy, beta-delayed gamma-­ray spectroscopy is a potential, non-­destructive assay techniques for the independent verification of declared quantities of special nuclear materials at key stages of the fuel cycle and for directly assaying nuclear material inventories for spent fuel handling, interim storage, reprocessing facilities, repository sites, and final disposal. Other potential applications include determination of MOX fuel composition, characterization of nuclear waste packages, and challenges in homeland security and arms control verification. Experimental measurements were performed to evaluate fission fragment yields, to test methods for determining isotopic fractions, and to benchmark the modeling code package. Experimental measurement campaigns were carried outmore » at the IAC using a photo-­neutron source and at OSU using a thermal neutron beam from the TRIGA reactor to characterize the emission of high-­energy delayed gamma rays from 235U, 239Pu, and 241Pu targets following neutron induced fission. Data were collected for pure and combined targets for several irradiation/spectroscopy cycle times ranging from 10/10 seconds to 15/30 minutes.The delayed gamma-ray signature of 241Pu, a significant fissile constituent in spent fuel, was measured and compared to 239Pu. The 241Pu/ 239Pu ratios varied between 0.5 and 1.2 for ten prominent lines in the 2700-­3600 keV energy range. Such significant differences in relative peak intensities make it possible to determine relative fractions of these isotopes in a mixed sample. A method for determining fission product yields by fitting the energy and time dependence of the delayed gamma-­ray emission was developed and demonstrated on a limited 235U data set. De-­convolution methods for determining fissile fractions were developed and tested on the experimental data. The use of high count-­rate LaBr 3 detectors was investigated as a potential alternative to HPGe detectors. Modeling capabilities

  17. Exploitation of Geometric Occlusion and Covariance Spectroscopy in a Gamma Sensor Array

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald

    2013-09-01

    The National Security Technologies, LLC, Remote Sensing Laboratory has recently used an array of six small-footprint (1-inch diameter by 3-inch long) cylindrical crystals of thallium-doped sodium iodide scintillators to obtain angular information from discrete gamma ray–emitting point sources. Obtaining angular information in a near-field measurement for a field-deployed gamma sensor is a requirement for radiological emergency work. Three of the sensors sit at the vertices of a 2-inch isosceles triangle, while the other three sit on the circumference of a 3-inch-radius circle centered in this triangle. This configuration exploits occlusion of sensors, correlation from Compton scattering within a detector array,more » and covariance spectroscopy, a spectral coincidence technique. Careful placement and orientation of individual detectors with reference to other detectors in an array can provide improved angular resolution for determining the source position by occlusion mechanism. By evaluating the values of, and the uncertainties in, the photopeak areas, efficiencies, branching ratio, peak area correction factors, and the correlations between these quantities, one can determine the precise activity of a particular radioisotope from a mixture of radioisotopes that have overlapping photopeaks that are ordinarily hard to deconvolve. The spectral coincidence technique, often known as covariance spectroscopy, examines the correlations and fluctuations in data that contain valuable information about radiation sources, transport media, and detection systems. Covariance spectroscopy enhances radionuclide identification techniques, provides directional information, and makes weaker gamma-ray emission—normally undetectable by common spectroscopic analysis—detectable. A series of experimental results using the concept of covariance spectroscopy are presented.« less

  18. Application of neuro-fuzzy methods to gamma spectroscopy

    NASA Astrophysics Data System (ADS)

    Grelle, Austin L.

    Nuclear non-proliferation activities are an essential part of national security activities both domestic and abroad. The safety of the public in densely populated environments such as urban areas or large events can be compromised if devices using special nuclear materials are present. Therefore, the prompt and accurate detection of these materials is an important topic of research, in which the identification of normal conditions is also of importance. With gamma-ray spectroscopy, these conditions are identified as the radiation background, which though being affected by a multitude of factors is ever present. Therefore, in nuclear non-proliferation activities the accurate identification of background is important. With this in mind, a method has been developed to utilize aggregate background data to predict the background of a location through the use of an Artificial Neural Network (ANN). After being trained on background data, the ANN is presented with nearby relevant gamma-ray spectroscopy data---as identified by a Fuzzy Inference System - to create a predicted background spectra to compare to a measured spectra. If a significant deviation exists between the predicted and measured data, the method alerts the user such that a more thorough investigation can take place. Research herein focused on data from an urban setting in which the number of false positives was observed to be 28 out of a total of 987, representing 2.94% error. The method therefore currently shows a high rate of false positives given the current configuration, however there are promising steps that can be taken to further minimize this error. With this in mind, the method stands as a potentially significant tool in urban nuclear nonproliferation activities.

  19. Characterizing near-surface elemental layering on Mars using gamma-ray spectroscopy: A proof-of-principle experiment

    NASA Astrophysics Data System (ADS)

    Peplowski, Patrick N.; Wilson, Jack T.; Beck, Andrew W.; Burks, Morgan; Goldsten, John O.; Lawrence, David J.

    2018-01-01

    Gamma-ray spectroscopy investigations characterize the chemical composition of planetary surfaces by measuring element-characteristic gamma rays with energies of ∼100 keV to ∼9 MeV. Over this energy range, the mean free path of a gamma ray varies from about 1 to 25 cm, therefore gamma-ray measurements sample subsurface composition. Many elements emit gamma rays at multiple, often widely spaced energies, so gamma-ray measurements can in principle also be used to identify depth-dependent variations in subsurface composition. We report results from laboratory measurements and radiation transport modeling designed to demonstrate this capability. The laboratory measurements verified the presence of depth-dependent gamma-ray signatures, and were then used to benchmark radiation transport simulations that were used to model realistic Mars-like scenarios. The models indicate that compositionally distinct subsurface deposits, buried to depths of ∼80 cm (125 g/cm2), can be identified using gamma-ray measurements. Going beyond identification to characterization (burial depth, relative composition of the layers) of the deposits requires knowledge of the vertical and horizontal variability in the water content of the near-surface surface materials, the local Galactic Cosmic Ray environment (magnitude and energy distribution), the depth-dependent neutron flux, gamma-ray production cross sections, and knowledge of the composition and column density of the atmosphere. The results of our experiments and models provided a basis for examining the utility of using orbiter- and lander-based gamma-ray measurements to identify subsurface deposits on Mars.

  20. Applications of LaBr3(Ce) Gamma-ray Spectrometer Arrays for Nuclear Spectroscopy and Radionuclide Assay

    NASA Astrophysics Data System (ADS)

    Regan, PH; Shearman, R.; Daniel, T.; Lorusso, G.; Collins, SM; Judge, SM; Bell; Pearce, AK; Gurgi, LA; Rudigier, M.; Podolyák, Zs; Mărginean, N.; Mărginean, R.; Kisyov, S.

    2016-10-01

    An overview of the use of discrete energy gamma-ray detectors based on cerium- doped LaBr3 scintillators for use in nuclear spectroscopy is presented. This review includes recent applications of such detectors in mixed, 'hybrid' gamma-ray coincidence detection arrays such ROSPHERE at IFIN-HH, Bucharest; EXILL+FATIMA at ILL Grenoble, France; GAMMASPHERE+FATIMA at Argonne National Laboratory, USA; FATIMA + EURICA, at RIKEN, Japan; and the National Nuclear Array (NANA) at the UK's National Physical Laboratory. This conference paper highlights the capabilities and limitations of using these sub-nanosecond 'fast-timing', medium-resolution gamma-ray detectors for both nuclear structure research and radionuclide standardisation. Potential future application of such coincidence scintillator arrays in measurements of civilian nuclear fuel waste evaluation and assay is demonstrated using coincidence spectroscopy of a mixed 134,7Cs source.

  1. A gamma-ray spectroscopy survey of Omani meteorites

    NASA Astrophysics Data System (ADS)

    Weber, Patrick; Hofmann, Beda A.; Tolba, Tamer; Vuilleumier, Jean-Luc

    2017-06-01

    The gamma-ray activities of 33 meteorite samples (30 ordinary chondrites, 1 Mars meteorite, 1 iron, 1 howardite) collected during Omani-Swiss meteorite search campaigns 2001-2008 were nondestructively measured using an ultralow background gamma-ray detector. The results provide several types of information: Potassium and thorium concentrations were found to range within typical values for the meteorite types. Similar mean 26Al activities in groups of ordinary chondrites with (1) weathering degrees W0-1 and low 14C terrestrial age and (2) weathering degree W3-4 and high 14C terrestrial age are mostly consistent with activities observed in recent falls. The older group shows no significant depletion in 26Al. Among the least weathered samples, one meteorite (SaU 424) was found to contain detectable 22Na identifying it as a recent fall close to the year 2000. Based on an estimate of the surface area searched, the corresponding fall rate is 120 events/106 km2*a, consistent with other estimations. Twelve samples from the large JaH 091 strewn field (total mass 4.5 t) show significant variations of 26Al activities, including the highest values measured, consistent with a meteoroid radius of 115 cm. Activities of 238U daughter elements demonstrate terrestrial contamination with 226Ra and possible loss of 222Rn. Recent contamination with small amounts of 137Cs is ubiquitous. We conclude that gamma-ray spectroscopy of a selection of meteorites with low degrees of weathering is particularly useful to detect recent falls among meteorites collected in hot deserts.

  2. A phoswich detector for simultaneous alpha-gamma spectroscopy

    NASA Astrophysics Data System (ADS)

    Moghadam, S. Rajabi; Feghhi, S. A. H.; Safari, M. J.

    2015-11-01

    Phoswich detectors are of value for radiation spectroscopy, especially in cases where a low-cost solution for a mixed radiation field is desired. Meanwhile, simultaneous spectroscopy of alpha particles and gamma-rays has many applications in quantification and distinguishing the alpha-emitting radionuclides which usually occur in the analysis of environmental solid samples. Here, we have developed a system for detection of radioactive actinides (e.g., 241Am) based on the alpha-gamma coincidence technique. The underlying concept, is to assemble two appropriately selected scintillators (i.e., a fast and a slow one) together with a discriminating unit for analysis of their data. Detailed Monte Carlo simulation procedure has been developed using the GEANT4 toolkit to design and find enough knowledge about the response of the system in the studied radiation field. Various comparisons were made between experimental and simulation data which showed appropriate agreement between them. The calibration was performed and the MDA was estimated as 60 mBq for the phoswich system.

  3. A Method to Estimate the Atomic Number and Mass Thickness of Intervening Materials in Uranium and Plutonium Gamma-Ray Spectroscopy Measurements

    NASA Astrophysics Data System (ADS)

    Streicher, Michael; Brown, Steven; Zhu, Yuefeng; Goodman, David; He, Zhong

    2016-10-01

    To accurately characterize shielded special nuclear materials (SNM) using passive gamma-ray spectroscopy measurement techniques, the effective atomic number and the thickness of shielding materials must be measured. Intervening materials between the source and detector may affect the estimated source isotopics (uranium enrichment and plutonium grade) for techniques which rely on raw count rates or photopeak ratios of gamma-ray lines separated in energy. Furthermore, knowledge of the surrounding materials can provide insight regarding the configuration of a device containing SNM. The described method was developed using spectra recorded using high energy resolution CdZnTe detectors, but can be expanded to any gamma-ray spectrometers with energy resolution of better than 1% FWHM at 662 keV. The effective atomic number, Z, and mass thickness of the intervening shielding material are identified by comparing the relative attenuation of different gamma-ray lines and estimating the proportion of Compton scattering interactions to photoelectric absorptions within the shield. While characteristic Kα x-rays can be used to identify shielding materials made of high Z elements, this method can be applied to all shielding materials. This algorithm has adequately estimated the effective atomic number for shields made of iron, aluminum, and polyethylene surrounding uranium samples using experimental data. The mass thicknesses of shielding materials have been estimated with a standard error of less than 1.3 g/cm2 for iron shields up to 2.5 cm thick. The effective atomic number was accurately estimated to 26 ± 5 for all iron thicknesses.

  4. Evaluation of Multi-Channel ADCs for Gamma-Ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Tan, Hui; Hennig, Wolfgang; Walby, Mark D.; Breus, Dimitry; Harris, Jackson

    2013-04-01

    As nuclear physicists increasingly design large scale experiments with hundreds or thousands of detector channels, there are growing needs for high density readout electronics with good timing and energy resolution that at the same time offer lower cost per channel compared to existing commercial solutions. Recent improvements in the design of commercial analog to digital converters (ADCs) have resulted in a variety of multi-channel ADCs that are natural choice for designing such high density readout modules. However, multi-channel ADCs typically are designed for medical imaging/ultrasound applications and therefore are not rated for their spectroscopic characteristics. In this work, we evaluated the gamma-ray spectroscopic performance of several multi-channel ADCs, including their energy resolution, nonlinearity, and timing resolution. Some of these ADCs demonstrated excellent energy resolution, 2.66% FWHM at 662 keV with a LaBr3 or 1.78 keV FWHM at 1332.5 keV with a high purity germanium (HPGe) detector, and sub-nanosecond timing resolution with LaBr 3. We present results from these measurements to illustrate their suitability for gamma-ray spectroscopy.

  5. Digitized detection of gamma-ray signals concentrated in narrow time windows for transient positron annihilation lifetime spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kinomura, A., E-mail: a.kinomura@aist.go.jp; Suzuki, R.; Oshima, N.

    2014-12-15

    A pulsed slow-positron beam generated by an electron linear accelerator was directly used for positron annihilation lifetime spectroscopy without any positron storage devices. A waveform digitizer was introduced to simultaneously capture multiple gamma-ray signals originating from positron annihilation events during a single accelerator pulse. The positron pulse was chopped and bunched with the chopper signals also sent to the waveform digitizer. Time differences between the annihilation gamma-ray and chopper peaks were calculated and accumulated as lifetime spectra in a computer. The developed technique indicated that positron annihilation lifetime spectroscopy can be performed in a 20 μs time window at amore » pulse repetition rate synchronous with the linear accelerator. Lifetime spectra of a Kapton sheet and a thermally grown SiO{sub 2} layer on Si were successfully measured. Synchronization of positron lifetime measurements with pulsed ion irradiation was demonstrated by this technique.« less

  6. Digitized detection of gamma-ray signals concentrated in narrow time windows for transient positron annihilation lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Kinomura, A.; Suzuki, R.; Oshima, N.; O'Rourke, B. E.; Nishijima, T.; Ogawa, H.

    2014-12-01

    A pulsed slow-positron beam generated by an electron linear accelerator was directly used for positron annihilation lifetime spectroscopy without any positron storage devices. A waveform digitizer was introduced to simultaneously capture multiple gamma-ray signals originating from positron annihilation events during a single accelerator pulse. The positron pulse was chopped and bunched with the chopper signals also sent to the waveform digitizer. Time differences between the annihilation gamma-ray and chopper peaks were calculated and accumulated as lifetime spectra in a computer. The developed technique indicated that positron annihilation lifetime spectroscopy can be performed in a 20 μs time window at a pulse repetition rate synchronous with the linear accelerator. Lifetime spectra of a Kapton sheet and a thermally grown SiO2 layer on Si were successfully measured. Synchronization of positron lifetime measurements with pulsed ion irradiation was demonstrated by this technique.

  7. Determination of dosimetric and kinetic features of gamma irradiated solid calcium ascorbate dihydrate using ESR spectroscopy

    NASA Astrophysics Data System (ADS)

    Tuner, H.

    2013-01-01

    Effects of gamma radiation on solid calcium ascorbate dihydrate were studied using electron spin resonance (ESR) spectroscopy. Irradiated samples were found to present two specific ESR lines with shoulder at low and high magnetic field sides. Structural and kinetic features of the radicalic species responsible for experimental ESR spectrum were explored through the variations of the signal intensities with applied microwave power, variable temperature, high-temperature annealing and room temperature storage time studies. Dosimetric potential of the sample was also determined using spectrum area and measured signal intensity measurements. It was concluded that three radicals with different spectroscopic and kinetic features were produced upon gamma irradiation.

  8. Estimation of neutron spectrum in the low-level gamma spectroscopy system using unfolding procedure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Knežević, D., E-mail: david.knezevic@df.uns.ac.rs; Jovančević, N.; Krmar, M.

    2016-03-25

    The radiation resulting from neutron interactions with Ge nuclei in active volume of HPGe detectors is one of the main concerns in low-level gamma spectroscopy measurements [1,2]. It is usually not possible to measure directly spectrum of neutrons which strike detector. This paper explore the possibility of estimation of neutron spectrum using measured activities of certain Ge(n,γ) and Ge(n,n’) reactions (obtained from low-level gamma measurements), available ENDF cross section data and unfolding procedures. In this work HPGe detector with passive shield made from commercial low background lead was used for the measurement. The most important objective of this study wasmore » to reconstruct muon induced neutron spectrum created in the shield of the HPGe detector. MAXED [3] and GRAVEL [4] algorithms for neutron spectra unfolding were used. The results of those two algorithms were compared and we analyzed the sensitivity of the unfolding procedure to the various input parameters.« less

  9. Homogeneity of Gd-based garnet transparent ceramic scintillators for gamma spectroscopy

    NASA Astrophysics Data System (ADS)

    Seeley, Z. M.; Cherepy, N. J.; Payne, S. A.

    2013-09-01

    Transparent polycrystalline ceramic scintillators based on the composition Gd1.49Y1.49Ce0.02Ga2.2Al2.8O12 are being developed for gamma spectroscopy detectors. Scintillator light yield and energy resolution depend on the details of various processing steps, including powder calcination, green body formation, and sintering atmosphere. We have found that gallium sublimation during vacuum sintering creates compositional gradients in the ceramic and can degrade the energy resolution. While sintering in oxygen produces ceramics with uniform composition and little afterglow, light yields are reduced, compared to vacuum sintering. By controlling the atmosphere during the various process steps, we were able to minimize the gallium sublimation, resulting in a more homogeneous composition and improved gamma spectroscopy performance.

  10. In vivo magnetic resonance spectroscopy measurement of gray-matter and white-matter gamma-aminobutyric acid concentration in sensorimotor cortex using a motion-controlled MEGA point-resolved spectroscopy sequence.

    PubMed

    Bhattacharyya, Pallab K; Phillips, Micheal D; Stone, Lael A; Lowe, Mark J

    2011-04-01

    Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the brain. Understanding the GABA concentration, in vivo, is important to understand normal brain function. Using MEGA point-resolved spectroscopy sequence with interleaved water scans to detect subject motion, GABA level of sensorimotor cortex was measured using a voxel identified from a functional magnetic resonance imaging scan. The GABA level in a 20×20×20-mm(3) voxel consisting of 37%±7% gray matter, 52%±12% white matter and 11%±8% cerebrospinal fluid in the sensorimotor region was measured to be 1.43±0.48 mM. In addition, using linear regression analysis, GABA concentrations within gray and white matter were calculated to be 2.87±0.61 and 0.33±0.11 mM, respectively. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Statistical Methods Applied to Gamma-ray Spectroscopy Algorithms in Nuclear Security Missions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fagan, Deborah K.; Robinson, Sean M.; Runkle, Robert C.

    2012-10-01

    In a wide range of nuclear security missions, gamma-ray spectroscopy is a critical research and development priority. One particularly relevant challenge is the interdiction of special nuclear material for which gamma-ray spectroscopy supports the goals of detecting and identifying gamma-ray sources. This manuscript examines the existing set of spectroscopy methods, attempts to categorize them by the statistical methods on which they rely, and identifies methods that have yet to be considered. Our examination shows that current methods effectively estimate the effect of counting uncertainty but in many cases do not address larger sources of decision uncertainty—ones that are significantly moremore » complex. We thus explore the premise that significantly improving algorithm performance requires greater coupling between the problem physics that drives data acquisition and statistical methods that analyze such data. Untapped statistical methods, such as Bayes Modeling Averaging and hierarchical and empirical Bayes methods have the potential to reduce decision uncertainty by more rigorously and comprehensively incorporating all sources of uncertainty. We expect that application of such methods will demonstrate progress in meeting the needs of nuclear security missions by improving on the existing numerical infrastructure for which these analyses have not been conducted.« less

  12. Development of a Small-Sized, Flexible, and Insertable Fiber-Optic Radiation Sensor for Gamma-Ray Spectroscopy

    PubMed Central

    Yoo, Wook Jae; Shin, Sang Hun; Lee, Dong Eun; Jang, Kyoung Won; Cho, Seunghyun; Lee, Bongsoo

    2015-01-01

    We fabricated a small-sized, flexible, and insertable fiber-optic radiation sensor (FORS) that is composed of a sensing probe, a plastic optical fiber (POF), a photomultiplier tube (PMT)-amplifier system, and a multichannel analyzer (MCA) to obtain the energy spectra of radioactive isotopes. As an inorganic scintillator for gamma-ray spectroscopy, a cerium-doped lutetium yttrium orthosilicate (LYSO:Ce) crystal was used and two solid-disc type radioactive isotopes with the same dimensions, cesium-137 (Cs-137) and cobalt-60 (Co-60), were used as gamma-ray emitters. We first determined the length of the LYSO:Ce crystal considering the absorption of charged particle energy and measured the gamma-ray energy spectra using the FORS. The experimental results demonstrated that the proposed FORS can be used to discriminate species of radioactive isotopes by measuring their inherent energy spectra, even when gamma-ray emitters are mixed. The relationship between the measured photon counts of the FORS and the radioactivity of Cs-137 was subsequently obtained. The amount of scintillating light generated from the FORS increased by increasing the radioactivity of Cs-137. Finally, the performance of the fabricated FORS according to the length and diameter of the POF was also evaluated. Based on the results of this study, it is anticipated that a novel FORS can be developed to accurately measure the gamma-ray energy spectrum in inaccessible locations such as narrow areas and holes. PMID:26343667

  13. Particle-Induced Gamma-ray Emission Spectroscopy Over a Broad Range of Elements

    NASA Astrophysics Data System (ADS)

    Olds, Hannah; Wilkinson, John; Tighe, Meghanne; McLallen, Walter; McGuire, Patrick

    2017-09-01

    Ion beam analysis is a common application of nuclear physics that allows elemental and isotopic information about materials to be determined from accelerated light ion beams One of the best know ion beam analysis techniques is Particle-Induced Gamma-ray Emission (PIGE) spectroscopy, which can be used ex vacuo to identify the elements of interest in almost any solid target. The energies of the gamma-rays emitted by excited nuclei will be unique to each element and depend on its nuclear structure. For the most sensitivity, the accelerated ions should exceed the Coulomb barrier of the target, but many isotopes are known to be accessible to PIGE even below the Coulomb barrier. To explore the sensitivity of PIGE across the periodic table, PIGE measurements were made on elements with Z = 5, 9, 11-15, 17, 19-35, 37, 42, 44-48, 53, 56, 60, 62, 73, and 74 using 3.4 MeV protons. These measurements will be compared with literature values and be used as a basis for comparison with higher-energy proton beams available at the University of Notre Dame's St. Andre accelerator when it comes online this Fall. The beam normalization technique of using atmospheric argon and its 1459 keV gamma-ray to better estimate the integrated beam on target will also be discussed. Funded by the NSF REU program and the University of Notre Dame.

  14. ^235U(n,xnγ) Excitation Function Measurements Using Gamma-Ray Spectroscopy at GEANIE

    NASA Astrophysics Data System (ADS)

    Younes, W.; Becker, J. A.; Bernstein, L. A.; Archer, D. E.; Stoyer, M. A.; Hauschild, K.; Drake, D. M.; Johns, G. D.; Nelson, R. O.; Wilburn, S. W.

    1998-04-01

    The ^235U(n,xn) cross sections (where x<=2) have previously been measured at several incident neutron energies. In particular, the ^235U(n,2n) cross section has been measured(J. Frehaut et al.), Nucl. Sci. Eng. 74,29 (1980). reliably up to peak near E_n≈ 11 MeV, but not along the tail which is predicted by some(M.B. Chadwick, private communication.) codes to yield significant (e.g. >= 10% of peak) cross section out to E_n≈ 30 MeV. We have measured gamma-ray spectra resulting from ^235U(n,xn) as a function of neutron energy in the range 1 MeV <~ En <~ 200 MeV using the GEANIE spectrometer at the LANSCE/WNR ``white'' neutron source. We will present excitation functions for the de-excitation gamma rays in ^234,235U compared to predictions from the Hauser-Feshbach-preequilibrium code GNASH(M.B. Chadwick and P.G. Young, Los Alamos Report No. LA-UR-93-104, 1993.).

  15. Ultraviolet-visible and fluorescence spectroscopy can be used as a diagnostic tool for gamma irradiation detection in vivo.

    PubMed

    K-Abdelhalim, Mohamed Anwar; Moussa, Sherif A-Abdelmottaleb

    2016-09-01

    The spectroscopic properties can indicate important features about the nature and severity of the disease. However, no earlier studies have been used the spectroscopic properties as a diagnostic tool for radiation detection. This study was aimed to use ultraviolet-visible and fluorescence spectroscopy as a diagnostic tool for gamma irradiation detection in rats in vivo. Adult male rats were exposed to 25, 50, 75 and 100 Gray as single dose, using Cobalt-60 (Co-60) source with a dose rate of 0.883 centi Gray/sec (cGy/s). Ultraviolet and fluorescence spectroscopy of rat's blood serum were measured. After gamma irradiation of rats in vivo, the blood serum absorbance peaks for 25, 50, 75 and 100 Gray (Gy) decreased and shifted towards the ultra violet wavelength. A maximal change in fluorescence intensity of blood serum at 350 nm was obtained when exciting light at 194 nm after irradiation. The fluorescence intensity also decreased with the dose. The highest radiation gamma dose might be accompanied with the highest oxidative stress. This study suggests that at the above mentioned gamma radiation doses, the blood is highly fragmented; with low aggregation at 25 Gy and with high aggregation at 50-100 Gy.

  16. Distance dependent quenching and gamma-ray spectroscopy in tin-loaded polystyrene scintillators

    DOE PAGES

    Feng, Patrick L; Mengesha, Wondwosen; Anstey, Mitchell R.; ...

    2016-02-01

    In this study, we report the synthesis and inclusion of rationally designed organotin compounds in polystyrene matrices as a route towards plastic scintillators capable of gamma-ray spectroscopy. Tin loading ratios of up to 15% w/w have been incorporated, resulting in photopeak energy resolution values as low as 10.9% for 662 keV gamma-rays. Scintillator constituents were selected based upon a previously reported distance-dependent quenching mechanism. Data obtained using UV-Vis and photoluminescence measurements are consistent with this phenomenon and are correlated with the steric and electronic properties of the respective organotin complexes. We also report fast scintillation decay behavior that is comparablemore » to the quenched scintillators 0.5% trans-stilbene doped bibenzyl and the commercial plastic scintillator BC-422Q-1%. These observations are discussed in the context of practical considerations such as optical transparency, ease-of-preparation/scale-up, and total scintillator cost.« less

  17. Study of gamma spectrometry laboratory measurement in various sediment and vulcanic rocks

    NASA Astrophysics Data System (ADS)

    Nurhandoko, Bagus Endar B.; Kurniadi, Rizal; Rizka Asmara Hadi, Muhammad; Rizal Komara, Insan

    2017-01-01

    Gamma-ray spectroscopy is the quantitative study of the energy spectra of gamma-ray sources. This method is powerful to characterize some minerals, especially to differentiate rocks which contains among Potassium, Uranium, dan Thorium. Rock contains radioactive material which produce gamma rays in various energies and intensities. When these emissions are detected and analyzed with a spectroscopy system, a gamma-ray energy spectrum can be used as indicator for mineral content of rock. Some sediment and vulcanic rock have been collected from East Java Basin. Samples are ranging from Andesite vulcanics, Tuff, Shale, various vulcanic clay and Alluvial clay. We present some unique characteristics of gamma spectrometry in various sedimentar and vulcanic rocks of East Java Basins. Details contents of gamma ray spectra give enrichments to characterize sample of sediment and vulcanic in East Java. Weathered vulcanic clay has lower counting rate of gamma ray than alluvial deltaic clay counting rate. Therefore, gamma spectrometrometry can be used as tool for characterizing the enviroment of clay whether vulcanic or alluvial-deltaic. This phenomena indicates that gamma ray spectrometry can be as tool for characterizing the clay whether it tends to Smectite or Illite

  18. Delayed Gamma-ray Spectroscopy for Safeguards Applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mozin, Vladimir

    The delayed gamma-ray assay technique utilizes an external neutron source (D-D, D-T, or electron accelerator-driven), and high-resolution gamma-ray spectrometers to perform characterization of SNM materials behind shielding and in complex configurations such as a nuclear fuel assembly. High-energy delayed gamma-rays (2.5 MeV and above) observed following the active interrogation, provide a signature for identification of specific fissionable isotopes in a mixed sample, and determine their relative content. Potential safeguards applications of this method are: 1) characterization of fresh and spent nuclear fuel assemblies in wet or dry storage; 2) analysis of uranium enrichment in shielded or non-characterized containers or inmore » the presence of a strong radioactive background and plutonium contamination; 3) characterization of bulk and waste and product streams at SNM processing plants. Extended applications can include warhead confirmation and warhead dismantlement confirmation in the arms control area, as well as SNM diagnostics for the emergency response needs. In FY16 and prior years, the project has demonstrated the delayed gamma-ray measurement technique as a robust SNM assay concept. A series of empirical and modeling studies were conducted to characterize its response sensitivity, develop analysis methodologies, and analyze applications. Extensive experimental tests involving weapons-grade Pu, HEU and depleted uranium samples were completed at the Idaho Accelerator Center and LLNL Dome facilities for various interrogation time regimes and effects of the neutron source parameters. A dedicated delayed gamma-ray response modeling technique was developed and its elements were benchmarked in representative experimental studies, including highresolution gamma-ray measurements of spent fuel at the CLAB facility in Sweden. The objective of the R&D effort in FY17 is to experimentally demonstrate the feasibility of the delayed gamma-ray interrogation of shielded

  19. Gamma Ray Spectroscopy: Some highlights from the past, present and future

    NASA Astrophysics Data System (ADS)

    Beausang, Cornelius

    2007-04-01

    The early implementation stages of the current generation of large scale gamma-ray spectrometers, EUROGAM Phase 1 closely followed by Gammasphere Early Implementation, came online in the early 1990's. Last August the tenth anniversary of the full Gammasphere Array was celebrated. Large arrays of Compton suppressed Ge detectors, such as Gammasphere, Eurogam/Euroball/Jurosphere operated in both stand alone mode and, more recently, when coupled to highly selective and sensitive channel selection devices, such as the Fragment Mass Analyzer or RITU, or auxiliary detectors, such as Microball and Chico, have led to an unprecedented increase in our knowledge of the properties of the atomic nucleus when stressed by the application of high angular momentum, large proton or neutron imbalance, high temperatures etc. Gamma-ray spectroscopy is now routinely carried out at the limits of nuclear existence, either in terms of mass or in nuclei on, or beyond, the drip-lines. This talk will touch upon some of the classic results obtained with such arrays, will review the current state of the art in gamma-ray spectroscopy and consider some potentials for the future of the field with new arrays such as GRETA in the US and AGATA in Europe. This work is supported by the US Department of Energy under grant numbers DE-FG52-06NA26206 and DE-FG02-05ER41379.

  20. Enrichment Meter Dataset from High-Resolution Gamma Spectroscopy Measurements of U3O8 Enrichment Standards and UF6 Cylinder Wall Equivalents

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nicholson, Andrew D.; Croft, Stephen; Shephard, Adam M.

    2015-12-01

    The Enrichment Meter Principle (EMP) is the basis for a commonly used standard test method for the non-destructive assay of 235U enrichment in bulk compounds [1]. The technique involves determining the net count rate in the direct 186 keV peak using medium or high energy gamma-ray spectrometry in a fixed geometry. With suitable correction for wall attenuation, compound type, rate loss (live time), and peaked background (if significant), the atom fraction of 235U may be obtained from the counting rate from a linear relationship through the origin. The widespread use of this method for field verification of enrichment [2,3] togethermore » with the fact that the response function rests on fundamental physics considerations (i.e., is not represented by a convenient but arbitrary form) makes it an interesting example of uncertainty quantification, one in which one can expect a valid measurement model can be applied. When applied using NaI(Tl) and region of interest analysis, the technique is susceptible to both interference error and bias [2-4]. When implemented using high-resolution gamma-ray spectroscopy, the spectrum interpretation is considerable simplified and more robust [5]. However, a practical challenge to studying the uncertainty budget of the EMP method (for example, to test linearity, extract wall corrections and so forth using modern methods) is the availability of quality experimental data that can be referenced and shared. To fill this gap, the research team undertook an experimental campaign [6]. A measurement campaign was conducted to produce high-resolution gamma spectroscopy enrichment meter data comparable to UF 6 cylinder measurements. The purpose of this report is to provide both an introduction to and quality assurance (QA) of the raw data produced. This report is intended for the analyst or researcher who uses the raw data. Unfortunately, the raw data (i.e., the spectra files) are too voluminous to include in this report but can be requested

  1. Measurement of absolute gamma emission probabilities

    NASA Astrophysics Data System (ADS)

    Sumithrarachchi, Chandana S.; Rengan, Krish; Griffin, Henry C.

    2003-06-01

    The energies and emission probabilities (intensities) of gamma-rays emitted in radioactive decays of particular nuclides are the most important characteristics by which to quantify mixtures of radionuclides. Often, quantification is limited by uncertainties in measured intensities. A technique was developed to reduce these uncertainties. The method involves obtaining a pure sample of a nuclide using radiochemical techniques, and using appropriate fractions for beta and gamma measurements. The beta emission rates were measured using a liquid scintillation counter, and the gamma emission rates were measured with a high-purity germanium detector. Results were combined to obtain absolute gamma emission probabilities. All sources of uncertainties greater than 0.1% were examined. The method was tested with 38Cl and 88Rb.

  2. Applications of the low-background gamma spectroscopy to the geographical origin of marine salts and prunes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Perrot, F.

    The low background gamma spectroscopy has been applied to try to sign the geographical origin of the French atlantic marine salts and of the prunes from Agen. Most of the activity measurements have been done using low background Ge spectrometers located in Bordeaux. Results have shown that a clear signature exists in the case of the French atlantic salts using the 40K, 137Cs and 226Ra isotopes but not in the case of the prunes.

  3. EP-DRAFT-1.1 2014-01-19 OSI-GAM-SOP-00x In Situ High-resolution Gamma Spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wimer, N. G.; Kreek, S. A.

    2014-01-27

    The standard operating procedure is described for in situ high-resolution gamma spectroscopy, including operational readiness, planning, preparation, conduct, and reporting. Data analysis of in situ gamma spectrum files will be performed together with those of other gamma assay methods by a dedicated Data Analysis process, documented in companion OSI procedures.

  4. Gamma-ray spectroscopy at MHz counting rates with a compact LaBr3 detector and silicon photomultipliers for fusion plasma applications.

    PubMed

    Nocente, M; Rigamonti, D; Perseo, V; Tardocchi, M; Boltruczyk, G; Broslawski, A; Cremona, A; Croci, G; Gosk, M; Kiptily, V; Korolczuk, S; Mazzocco, M; Muraro, A; Strano, E; Zychor, I; Gorini, G

    2016-11-01

    Gamma-ray spectroscopy measurements at MHz counting rates have been carried out, for the first time, with a compact spectrometer based on a LaBr 3 scintillator and silicon photomultipliers. The instrument, which is also insensitive to magnetic fields, has been developed in view of the upgrade of the gamma-ray camera diagnostic for α particle measurements in deuterium-tritium plasmas of the Joint European Torus. Spectra were measured up to 2.9 MHz with a projected energy resolution of 3%-4% in the 3-5 MeV range, of interest for fast ion physics studies in fusion plasmas. The results reported here pave the way to first time measurements of the confined α particle profile in high power plasmas of the next deuterium-tritium campaign at the Joint European Torus.

  5. Time-resolved gamma spectroscopy of single events

    NASA Astrophysics Data System (ADS)

    Wolszczak, W.; Dorenbos, P.

    2018-04-01

    In this article we present a method of characterizing scintillating materials by digitization of each individual scintillation pulse followed by digital signal processing. With this technique it is possible to measure the pulse shape and the energy of an absorbed gamma photon on an event-by-event basis. In contrast to time-correlated single photon counting technique, the digital approach provides a faster measurement, an active noise suppression, and enables characterization of scintillation pulses simultaneously in two domains: time and energy. We applied this method to study the pulse shape change of a CsI(Tl) scintillator with energy of gamma excitation. We confirmed previously published results and revealed new details of the phenomenon.

  6. Characterization of a tin-loaded liquid scintillator for gamma spectroscopy and neutron detection

    NASA Astrophysics Data System (ADS)

    Wen, Xianfei; Harvey, Taylor; Weinmann-Smith, Robert; Walker, James; Noh, Young; Farley, Richard; Enqvist, Andreas

    2018-07-01

    A tin-loaded liquid scintillator has been developed for gamma spectroscopy and neutron detection. The scintillator was characterized in regard to energy resolution, pulse shape discrimination, neutron light output function, and timing resolution. The loading of tin into scintillators with low effective atomic number was demonstrated to provide photopeaks with acceptable energy resolution. The scintillator was shown to have reasonable neutron/gamma discrimination capability based on the charge comparison method. The effect on the discrimination quality of the total charge integration time and the initial delay time for tail charge integration was studied. To obtain the neutron light output function, the time-of-flight technique was utilized with a 252Cf source. The light output function was validated with the MCNPX-PoliMi code by comparing the measured and simulated pule height spectra. The timing resolution of the developed scintillator was also evaluated. The tin-loading was found to have negligible impact on the scintillation decay times. However, a relatively large degradation of timing resolution was observed due to the reduced light yield.

  7. Camel molar tooth enamel response to gamma rays using EPR spectroscopy.

    PubMed

    El-Faramawy, N A; El-Somany, I; Mansour, A; Maghraby, A M; Eissa, H; Wieser, A

    2018-03-01

    Tooth enamel samples from molar teeth of camel were prepared using a combined procedure of mechanical and chemical tooth treatment. Based on electron paramagnetic resonance (EPR) spectroscopy, the dose response of tooth enamel samples was examined and compared to that of human enamel. The EPR dose response of the tooth enamel samples was obtained through irradiation to gamma doses from 1 Gy up to 100 kGy. It was found that the radiation-induced EPR signal increased linearly with gamma dose for all studied tooth enamel samples, up to about 15 kGy. At higher doses, the dose response curve leveled off. The results revealed that the location of the native signal of camel tooth enamel was similar to that of enamel from human molars at 2.00644, but different from that of enamel from cows and goats. In addition, the peak-to-peak width (ΔH pp ) for human and camel molar teeth was similar. It was also found that the response of camel enamel to gamma radiation was 36% lower than that of human enamel. In conclusion, the results indicate the suitability of camel teeth for retrospective gamma dosimetry.

  8. Measuring the charged pion polarizability in the gamma gamma -> pi+pi- reaction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lawrence, David W.; Miskimen, Rory A.; Mushkarenkov, Alexander Nikolaevich

    2013-08-01

    Development has begun of a new experiment to measure the charged pion polarizabilitymore » $$\\alpha_{\\pi}-\\beta_{\\pi}$$. The charged pion polarizability ranks among the most important tests of low-energy QCD presently unresolved by experiment. Analogous to precision measurements of $$\\pi^{\\circ}\\rightarrow\\gamma\\gamma$$ that test the intrinsic odd-parity (anomalous) sector of QCD, the pion polarizability tests the intrinsic even-parity sector of QCD. The measurement will be performed using the $$\\gamma\\gamma\\rightarrow\\pi^{+{}}\\pi^{-{}}$$ cross section accessed via the Primakoff mechanism on nuclear targets using the GlueX detector in Hall D at Jefferson Lab. The linearly polarized photon source in Hall-D will be utilized to separate the Primakoff cross-section from coherent $$\\rho^{\\circ}$$ production.« less

  9. Testing FLUKA on neutron activation of Si and Ge at nuclear research reactor using gamma spectroscopy

    NASA Astrophysics Data System (ADS)

    Bazo, J.; Rojas, J. M.; Best, S.; Bruna, R.; Endress, E.; Mendoza, P.; Poma, V.; Gago, A. M.

    2018-03-01

    Samples of two characteristic semiconductor sensor materials, silicon and germanium, have been irradiated with neutrons produced at the RP-10 Nuclear Research Reactor at 4.5 MW. Their radionuclides photon spectra have been measured with high resolution gamma spectroscopy, quantifying four radioisotopes (28Al, 29Al for Si and 75Ge and 77Ge for Ge). We have compared the radionuclides production and their emission spectrum data with Monte Carlo simulation results from FLUKA. Thus we have tested FLUKA's low energy neutron library (ENDF/B-VIIR) and decay photon scoring with respect to the activation of these semiconductors. We conclude that FLUKA is capable of predicting relative photon peak amplitudes, with gamma intensities greater than 1%, of produced radionuclides with an average uncertainty of 13%. This work allows us to estimate the corresponding systematic error on neutron activation simulation studies of these sensor materials.

  10. Solid state structural investigations of the bis(chalcone) compound with single crystal X-ray crystallography, DFT, gamma-ray spectroscopy and chemical spectroscopy methods

    NASA Astrophysics Data System (ADS)

    Yakalı, Gül; Biçer, Abdullah; Eke, Canel; Cin, Günseli Turgut

    2018-04-01

    A bis(chalcone), (2E,6E)-2,6-bis((E)-3phenylallidene)cyclohexanone, was characterized by 1H NMR, 13C NMR, FTIR, UV-Vis spectroscopy, gamma-ray spectroscopy and single crystal X- ray structural analysis. The optimized molecular structure of the compound is calculated using DFT/B3LYP with 6-31G (d,p) level. The calculated geometrical parameters are in good agreement with the experimental data obtained from our reported X-ray structure. The powder and single crystal compounds were gama-irradiated using clinical electron linear accelerator and 60Co gamma-ray source, respectively. Spectral studies (1H NMR, 13C NMR, FTIR and UV-Vis) of powder chalcone compound were also investigated before and after irradiation. Depending on the irradiation notable changes were observed in spectral features powder sample. Single crystal X-ray diffraction investigation shows that both unirradiated and irradiated single crystal samples crystallizes in a orthorhombic crystal system in the centrosymmetric space group Pbcn and exhibits an C-H..O intramolecular and intermolecular hydrogen bonds. The crystal packing is stabilised by strong intermolecular bifurcate C-H..O hydrogen bonds and π…π stacking interactions. The asymmetric unit of the title compound contains one-half of a molecule. The other half of the molecule is generated with (1-x,y,-3/2-z) symmetry operator. The molecule is almost planar due to having π conjugated system of chalcones. However, irradiated single crystal compound showed significant changes lattice parameters, crystal volume and density. According to results of gamma-ray spectroscopy, radioactive elements of powder compound which are 123Sb(n,g),124Sb,57Fe(g,p),56Mn, 55Mn(g,n), and 54Mn were determined using photoactivation analysis. However, the most intensive gamma-ray energy signals are 124Sb.

  11. Gamma Ray Spectroscopy and SASSYER

    NASA Astrophysics Data System (ADS)

    Pauerstein, Benjamin; Bonniwell, Cain; Allmond, J. M.; Beausang, C. W.

    2009-10-01

    An experiment was performed to study the Gd and Tb nuclei resulting from a 27 MeV proton beam on a 156Gd target. This was conducted at Lawrence Berkeley National Laboratory using the STARS/LIBERACE array. The main focus of the experiment was on charged particle channels (p,d) into 155Gd and (p,t) into 154Gd. However, the trigger was either gamma-gamma or particle-gamma so new data was also obtained on 155Tb nuclei following fusion evaporation reactions. Preliminary analysis was conducted at Wright Nuclear Structure Lab where RADWARE programs were used to analyze the data and search for unknown gamma rays. A second, separate, experiment was conducted using the SASSYER (a gas-filled separator at Yale). In this experiment, fission fragments from a 252Cf source were focused to a DSSD and a Ge detector was used to search for either gamma-decay from long lived isomers in the fission fragments or to find gammas from recoil-beta-decay tagging on the fission fragments. The data collection seems to have gone smoothly, and the data is currently being sorted for analysis. This work was supported by the US Department of Energy under grant numbers DE-FG02-52NA26206 and DE-FG02-05ER41379.

  12. Coupled multi-group neutron photon transport for the simulation of high-resolution gamma-ray spectroscopy applications

    NASA Astrophysics Data System (ADS)

    Burns, Kimberly Ann

    demonstrates a proof-of-concept of the method for use in RADSAT for coupled neutron-photon problems in high-resolution gamma-ray spectroscopy applications. One of the primary motivators for using the coupled method over pure Monte Carlo method is the potential for significantly lower computational times. For the code-to-code comparison cases, the run times for RADSAT were approximately 25--500 times shorter than for MCNP, as shown in Table 1. This was assuming a 40 mCi 252Cf neutron source and 600 seconds of "real-world" measurement time. The only variance reduction technique implemented in the MCNP calculation was forward biasing of the source toward the sample target. Improved MCNP runtimes could be achieved with the addition of more advanced variance reduction techniques.

  13. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy.

    PubMed

    Ji, J; Colosimo, A M; Anwand, W; Boatner, L A; Wagner, A; Stepanov, P S; Trinh, T T; Liedke, M O; Krause-Rehberg, R; Cowan, T E; Selim, F A

    2016-08-23

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials.

  14. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy

    NASA Astrophysics Data System (ADS)

    Ji, J.; Colosimo, A. M.; Anwand, W.; Boatner, L. A.; Wagner, A.; Stepanov, P. S.; Trinh, T. T.; Liedke, M. O.; Krause-Rehberg, R.; Cowan, T. E.; Selim, F. A.

    2016-08-01

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials.

  15. ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy

    PubMed Central

    Ji, J.; Colosimo, A. M.; Anwand, W.; Boatner, L. A.; Wagner, A.; Stepanov, P. S.; Trinh, T. T.; Liedke, M. O.; Krause-Rehberg, R.; Cowan, T. E.; Selim, F. A.

    2016-01-01

    The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials. PMID:27550235

  16. Lunar occultations for gamma-ray source measurements

    NASA Technical Reports Server (NTRS)

    Koch, David G.; Hughes, E. B.; Nolan, Patrick L.

    1990-01-01

    The unambiguous association of discrete gamma-ray sources with objects radiating at other wavelengths, the separation of discrete sources from the extended emission within the Galaxy, the mapping of gamma-ray emission from nearby galaxies and the measurement of structure within a discrete source cannot presently be accomplished at gamma-ray energies. In the past, the detection processes used in high-energy gamma-ray astronomy have not allowed for good angular resolution. This problem can be overcome by placing gamma-ray detectors on the moon and using the horizon as an occulting edge to achieve arcsec resolution. For purposes of discussion, this concept is examined for gamma rays above 100 MeV for which pair production dominates the detection process and locally-generated nuclear gamma rays do not contribute to the background.

  17. Gamma model and its analysis for phase measuring profilometry.

    PubMed

    Liu, Kai; Wang, Yongchang; Lau, Daniel L; Hao, Qi; Hassebrook, Laurence G

    2010-03-01

    Phase measuring profilometry is a method of structured light illumination whose three-dimensional reconstructions are susceptible to error from nonunitary gamma in the associated optical devices. While the effects of this distortion diminish with an increasing number of employed phase-shifted patterns, gamma distortion may be unavoidable in real-time systems where the number of projected patterns is limited by the presence of target motion. A mathematical model is developed for predicting the effects of nonunitary gamma on phase measuring profilometry, while also introducing an accurate gamma calibration method and two strategies for minimizing gamma's effect on phase determination. These phase correction strategies include phase corrections with and without gamma calibration. With the reduction in noise, for three-step phase measuring profilometry, analysis of the root mean squared error of the corrected phase will show a 60x reduction in phase error when the proposed gamma calibration is performed versus 33x reduction without calibration.

  18. Identification of lunar rock types and search for polar ice by gamma ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Metzger, A. E.; Drake, D. M.

    1990-01-01

    This paper examines the possibility of mapping the surface composition of the moon from an orbiting spin-stabilized spacecraft, using gamma ray spectroscopy and a cooled germanium solid-state device as a detector. A design for accommodating the germanium detector gamma ray spectrometer was devised, and the detection sensitivity was applied to typical lunar-rock compositions. For sets comprising nine highland and 16 mare types, the most useful elements were found to be Mg, Al, K, Ti, Fe, U, and Th. An analysis of the expected instrument response to the gamma ray and neutron fluxes of water ice indicated that a neutron mode added to the spectrometer will be more sensitive than the gamma ray mode to the possible presence of polar ice. It was calculated that, with a pair of selected neutron absorbers and a model which provides that 2.5 percent of the area above 75-deg latitude is occupied by trapping sites, the instrument will provide a 1-yr mission detection limit of 0.056 percent H2O by weight for each polar region.

  19. A Multi-Contact, Low Capacitance HPGe Detector for High Rate Gamma Spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cox, Christopher

    2014-12-04

    The detection, identification and non-destructive assay of special nuclear materials and nuclear fission by-products are critically important activities in support of nuclear non-proliferation programs. Both national and international nuclear safeguard agencies recognize that current accounting methods for spent nuclear fuel are inadequate from a safeguards perspective. Radiation detection and analysis by gamma-ray spectroscopy is a key tool in this field, but no instrument exists that can deliver the required performance (energy resolution and detection sensitivity) in the presence of very high background count rates encountered in the nuclear safeguards arena. The work of this project addresses this critical need bymore » developing a unique gamma-ray detector based on high purity germanium that has the previously unachievable property of operating in the 1 million counts-per-second range while achieving state-of-the-art energy resolution necessary to identify and analyze the isotopes of interest. The technical approach was to design and fabricate a germanium detector with multiple segmented electrodes coupled to multi-channel high rate spectroscopy electronics. Dividing the germanium detector’s signal electrode into smaller sections offers two advantages; firstly, the energy resolution of the detector is potentially improved, and secondly, the detector is able to operate at higher count rates. The design challenges included the following; determining the optimum electrode configuration to meet the stringent energy resolution and count rate requirements; determining the electronic noise (and therefore energy resolution) of the completed system after multiple signals are recombined; designing the germanium crystal housing and vacuum cryostat; and customizing electronics to perform the signal recombination function in real time. In this phase I work, commercial off-the-shelf electrostatic modeling software was used to develop the segmented germanium crystal

  20. Proximal Gamma-Ray Spectroscopy to Predict Soil Properties Using Windows and Full-Spectrum Analysis Methods

    PubMed Central

    Mahmood, Hafiz Sultan; Hoogmoed, Willem B.; van Henten, Eldert J.

    2013-01-01

    Fine-scale spatial information on soil properties is needed to successfully implement precision agriculture. Proximal gamma-ray spectroscopy has recently emerged as a promising tool to collect fine-scale soil information. The objective of this study was to evaluate a proximal gamma-ray spectrometer to predict several soil properties using energy-windows and full-spectrum analysis methods in two differently managed sandy loam fields: conventional and organic. In the conventional field, both methods predicted clay, pH and total nitrogen with a good accuracy (R2 ≥ 0.56) in the top 0–15 cm soil depth, whereas in the organic field, only clay content was predicted with such accuracy. The highest prediction accuracy was found for total nitrogen (R2 = 0.75) in the conventional field in the energy-windows method. Predictions were better in the top 0–15 cm soil depths than in the 15–30 cm soil depths for individual and combined fields. This implies that gamma-ray spectroscopy can generally benefit soil characterisation for annual crops where the condition of the seedbed is important. Small differences in soil structure (conventional vs. organic) cannot be determined. As for the methodology, we conclude that the energy-windows method can establish relations between radionuclide data and soil properties as accurate as the full-spectrum analysis method. PMID:24287541

  1. Gamma-Ray Background Variability in Mobile Detectors

    NASA Astrophysics Data System (ADS)

    Aucott, Timothy John

    Gamma-ray background radiation significantly reduces detection sensitivity when searching for radioactive sources in the field, such as in wide-area searches for homeland security applications. Mobile detector systems in particular must contend with a variable background that is not necessarily known or even measurable a priori. This work will present measurements of the spatial and temporal variability of the background, with the goal of merging gamma-ray detection, spectroscopy, and imaging with contextual information--a "nuclear street view" of the ubiquitous background radiation. The gamma-ray background originates from a variety of sources, both natural and anthropogenic. The dominant sources in the field are the primordial isotopes potassium-40, uranium-238, and thorium-232, as well as their decay daughters. In addition to the natural background, many artificially-created isotopes are used for industrial or medical purposes, and contamination from fission products can be found in many environments. Regardless of origin, these backgrounds will reduce detection sensitivity by adding both statistical as well as systematic uncertainty. In particular, large detector arrays will be limited by the systematic uncertainty in the background and will suffer from a high rate of false alarms. The goal of this work is to provide a comprehensive characterization of the gamma-ray background and its variability in order to improve detection sensitivity and evaluate the performance of mobile detectors in the field. Large quantities of data are measured in order to study their performance at very low false alarm rates. Two different approaches, spectroscopy and imaging, are compared in a controlled study in the presence of this measured background. Furthermore, there is additional information that can be gained by correlating the gamma-ray data with contextual data streams (such as cameras and global positioning systems) in order to reduce the variability in the background

  2. Measurement of the {sup 157}Gd(n,{gamma}) reaction with the DANCE {gamma} calorimeter array

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chyzh, A.; Dashdorj, D.; Lawrence Livermore National Laboratory, Livermore, California 94551

    2011-07-15

    The {sup 157}Gd(n,{gamma}) reaction was measured with the DANCE {gamma} calorimeter (consisting of 160 BaF{sub 2} scintillation detectors) at the Los Alamos Neutron Science Center. The multiplicity distributions of the {gamma} decay were used to determine the resonance spins up to E{sub n}=300 eV. The {gamma}-ray energy spectra for different multiplicities were measured for the s-wave resonances. The shapes of these spectra were compared with simulations based on the use of the DICEBOX statistical model code. Simulations showed that the scissors mode is required not only for the ground-state transitions but also for transitions between excited states.

  3. PING Gamma Ray and Neutron Measurements of a Meter-Sized Carbonaceous Asteroid Analog

    NASA Technical Reports Server (NTRS)

    Bodnarik, J.; Burger, D.; Evans, L.; Floyd, S.; Lim, L.; McClanahan, T.; Namkung, M.; Nowicki, S.; Parsons, A.; Schweitzer, J.; hide

    2011-01-01

    Determining the elemental composition of carbonaceous (spectral type C) asteroids is still one of the basic problems when studying these objects. The only main source of elemental composition information for asteroids is from their optical, NIR and IR properties, which include their spectral reflectance characteristics, albedo, polarization, and the comparison of optical spectroscopy with meteorite groups corresponding to asteroids of every spectral type. Unfortunately, these sources reflect observations from widely contrasting spatial scales that presently yield a void in the continuum of microscopic and macroscopic evidence, a lack of in situ measurement confirmation, and require deeper sensing techniques to discern the nature of these asteroids. The Probing In situ with Neutrons and Gamma rays (PING) instrument is ideally suited to address this problem because it can be used to determine the bulk elemental composition, H and C content, the average atomic weight and density of the surface and subsurface layers of C-type asteroids, and can provide measurements used to determine the difference between and distinguish between different types of asteroids. We are currently developing the PING instrument that combines gamma ray and neutron detectors with a 14 Me V pulsed neutron generator to determine the in-situ bulk elemental abundances and geochemistry of C-type asteroids with a spatial resolution of 1 m down to depths of tens of cm to 1 m. One aspect of the current work includes experimentally testing and optimizing PING on a known meter-sized Columbia River basalt C-type asteroid analog sample that has a similar composition and the same neutron response as that of a C-type asteroid. An important part of this effort focuses on utilizing timing measurements to isolate gamma rays produced by neutron inelastic scattering, neutron capture and delayed activation processes. Separating the gamma ray spectra by nuclear processes results in higher precision and sensitivity

  4. Accurate Wavelength Measurement of High-Energy Gamma Rays from the 35Cl(n,{gamma}) Reactions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Belgya, T.; Molnar, G.L.; Mutti, P.

    2005-05-24

    The energies of eight gamma rays in the 36Cl level scheme have been measured with high precision using the 35Cl(n,{gamma}) reaction and the GAMS4 spectrometer. From these energies, a skeleton decay scheme for 36Cl was constructed, and the binding energy of 36Cl was determined to higher precision than previously. It is shown that using this new information, binding energy determination from Ge detector experiments for other nuclei can also be made with higher precision than now available. The measurement of additional weaker 36Cl gamma rays is continuing.

  5. ICF Gamma-Ray measurements on the NIF

    NASA Astrophysics Data System (ADS)

    Herrmann, Hans; Kim, Y.; Hoffman, N. M.; Batha, S. H.; Stoeffl, W.; Church, J. A.; Sayre, D. B.; Liebman, J. A.; Cerjan, C. J.; Carpenter, A. C.; Grafil, E. M.; Khater, H. Y.; Horsfield, C. J.; Rubery, M.

    2013-10-01

    The primary objective of the NIF Gamma Reaction History (GRH) diagnostic is to provide bang time and burn width information in order to constrain implosion simulation parameters such as shell velocity and confinement time. This is accomplished by measuring DT fusion gamma-rays with energy-thresholded Gas Cherenkov detectors that convert MeV gamma-rays into UV/visible photons for high-bandwidth optical detection. Burn-weighted CH ablator areal density is also inferred based on measurement of the 12C(n,n') gammas emitted at 4.44 MeV from DT neutrons inelastically scattering off carbon nuclei as they pass through the plastic ablator. This requires that the four independent GRH gas cells be set to differing Cherenkov thresholds (e.g., 2.9, 4.5, 8 & 10 MeV) in order to be able to unfold the primary spectral components predicted to be in the gamma ray energy spectrum (i.e., DT γ 27Al & 28Si (n,n') γ from the thermo-mechanical package (TMP); and 12C(n,n' γ from the ablator). The GRH response to 12C(n,n') γ is calibrated in-situ by placing a known areal density of carbon in the form of a puck placed ~6 cm from a DT exploding pusher implosion. Comparisons between inferred gamma fluences and simulations based on the nuclear cross sections databases will be presented. Supported by US DOE NNSA.

  6. Neutron/Gamma-ray discrimination through measures of fit

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Amiri, Moslem; Prenosil, Vaclav; Cvachovec, Frantisek

    2015-07-01

    Statistical tests and their underlying measures of fit can be utilized to separate neutron/gamma-ray pulses in a mixed radiation field. In this article, first the application of a sample statistical test is explained. Fit measurement-based methods require true pulse shapes to be used as reference for discrimination. This requirement makes practical implementation of these methods difficult; typically another discrimination approach should be employed to capture samples of neutrons and gamma-rays before running the fit-based technique. In this article, we also propose a technique to eliminate this requirement. These approaches are applied to several sets of mixed neutron and gamma-ray pulsesmore » obtained through different digitizers using stilbene scintillator in order to analyze them and measure their discrimination quality. (authors)« less

  7. Fission prompt gamma-ray multiplicity distribution measurements and simulations at DANCE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chyzh, A; Wu, C Y; Ullmann, J

    2010-08-24

    The nearly energy independence of the DANCE efficiency and multiplicity response to {gamma} rays makes it possible to measure the prompt {gamma}-ray multiplicity distribution in fission. We demonstrate this unique capability of DANCE through the comparison of {gamma}-ray energy and multiplicity distribution between the measurement and numerical simulation for three radioactive sources {sup 22}Na, {sup 60}Co, and {sup 88}Y. The prospect for measuring the {gamma}-ray multiplicity distribution for both spontaneous and neutron-induced fission is discussed.

  8. Delayed Gamma Measurements in Different Nuclear Research Reactors Bringing Out the Importance of the Delayed Contribution in Gamma Flux Calculations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fourmentel, D.; Radulovic, V.; Barbot, L.

    Neutron and gamma flux levels are key parameters in nuclear research reactors. In Material Testing Reactors, such as the future Jules Horowitz Reactor, under construction at the French Alternative Energies and Atomic Energy Commission (CEA Cadarache, France), the expected gamma flux levels are very high (nuclear heating is of the order of 20 W/g at 100 MWth). As gamma rays deposit their energy in the reactor structures and structural materials it is important to take them into account when designing irradiation devices. There are only a few sensors which allow measurements of the nuclear heating ; a recent development atmore » the CEA Cadarache allows measurements of the gamma flux using a miniature ionization chamber (MIC). The measured MIC response is often compared with calculation using modern Monte Carlo (MC) neutron and photon transport codes, such as TRIPOLI-4 and MCNP6. In these calculations only the production of prompt gamma rays in the reactor is usually modelled thus neglecting the delayed gamma rays. Hence calculations and measurements are usually in better accordance for the neutron flux than for the gamma flux. In this paper we study the contribution of delayed gamma rays to the total MIC signal in order to estimate the systematic error in gamma flux MC calculations. In order to experimentally determine the delayed gamma flux contributions to the MIC response, we performed gamma flux measurements with CEA developed MIC at three different research reactors: the OSIRIS reactor (MTR - 70 MWth at CEA Saclay, France), the TRIGA MARK II reactor (TRIGA - 250 kWth at the Jozef Stefan Institute, Slovenia) and the MARIA reactor (MTR - 30 MWth at the National Center for Nuclear Research, Poland). In order to experimentally assess the delayed gamma flux contribution to the total gamma flux, several reactor shut down (scram) experiments were performed specifically for the purpose of the measurements. Results show that on average about 30 % of the MIC signal is

  9. The alterations in high density polyethylene properties with gamma irradiation

    NASA Astrophysics Data System (ADS)

    Zaki, M. F.; Elshaer, Y. H.; Taha, Doaa. H.

    2017-10-01

    In the present investigation, high density polyethylene (HDPE) polymer has been used to study the alterations in its properties under gamma-irradiation. Physico-chemical properties have been investigated with different spectroscopy techniques, Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), biocompatibility properties, as well as, mechanical properties change. The FT-IR analysis shows the formation of new band at 1716 cm-1 that is attributed to the oxidation of irradiated polymer chains, which is due to the formation of carbonyl groups (C˭O). XRD patterns show that a decrease in the crystallite size and increase in the Full Width at Half Maximum (FWHM). This means that the crystallinity of irradiated samples is decreased with increase in gamma dose. The contact angle measurements show an increase in the surface free energy as the gamma irradiation increases. The measurements of mechanical properties of irradiated HDPE samples were discussed.

  10. Bismuth- and lithium-loaded plastic scintillators for gamma and neutron detection

    NASA Astrophysics Data System (ADS)

    Cherepy, Nerine J.; Sanner, Robert D.; Beck, Patrick R.; Swanberg, Erik L.; Tillotson, Thomas M.; Payne, Stephen A.; Hurlbut, Charles R.

    2015-04-01

    Transparent plastic scintillators based on polyvinyltoluene (PVT) have been fabricated with high loading of bismuth carboxylates for gamma spectroscopy, and with lithium carboxylates for neutron detection. When activated with a combination of standard fluors, 2,5-diphenyloxazole (PPO) and tetraphenylbutadiene (TPB), gamma light yields with 15 wt% bismuth tripivalate of 5000 Ph/MeV are measured. A PVT plastic formulation including 30 wt% lithium pivalate and 30 wt% PPO offers both pulse shape discrimination, and a neutron capture peak at 400 keVee. In another configuration, a bismuth-loaded PVT plastic is coated with ZnS(6Li) paint, permitting simultaneous gamma and neutron detection via pulse shape discrimination with a figure-of-merit of 3.8, while offering gamma spectroscopy with energy resolution of R(662 keV)=15%.

  11. Benchmark Gamma Spectroscopy Measurements of Uranium Hexafluoride in Aluminmum Pipe with a Sodium Iodide Detector

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    March-Leuba, Jose A; Uckan, Taner; Gunning, John E

    2010-01-01

    monitor (FM) and an enrichment monitor (EM). Development of the FM is primarily the responsibility of Oak Ridge National Laboratory, and development of the EM is primarily the responsibility of Los Alamos National Laboratory. The FM will measure {sup 235}U mass flow rate by combining information from measuring the UF{sub 6} volumetric flow rate and the {sup 235}U density. The UF{sub 6} flow rate will be measured using characteristics of the process pumps used in product and tail UF{sub 6} header process lines of many GCEPs, and the {sup 235}U density will be measured using commercially available sodium iodide (NaI) gamma ray scintillation detectors. This report describes the calibration of the portion of the FM that measures the {sup 235}U density. Research has been performed to define a methodology and collect data necessary to perform this calibration without the need for plant declarations. The {sup 235}U density detector is a commercially available system (GammaRad made by Amptek, www.amptek.com) that contains the NaI crystal, photomultiplier tube, signal conditioning electronics, and a multichannel analyzer (MCA). Measurements were made with the detector system installed near four {sup 235}U sources. Two of the sources were made of solid uranium, and the other two were in the form of UF{sub 6} gas in aluminum piping. One of the UF{sub 6} gas sources was located at ORNL and the other at LANL. The ORNL source consisted of two pipe sections (schedule 40 aluminum pipe of 4-inch and 8-inch outside diameter) with 5.36% {sup 235}U enrichment, and the LANL source was a 4-inch schedule 40 aluminum pipe with 3.3% {sup 235}U enrichment. The configurations of the detector on these test sources, as well as on long straight pipe configurations expected to exist at GCEPs, were modeled using the computer code MCNP. The results of the MCNP calculations were used to define geometric correction factors between the test source and the GCEP application. Using these geometric correction

  12. A gamma-gamma coincidence/anticoincidence spectrometer for low-level cosmogenic (22)Na/(7)Be activity ratio measurement.

    PubMed

    Zhang, Weihua; Ungar, Kurt; Stukel, Matthew; Mekarski, Pawel

    2014-04-01

    In this study, a digital gamma-gamma coincidence/anticoincidence spectrometer was developed and examined for low-level cosmogenic (22)Na and (7)Be in air-filter sample monitoring. The spectrometer consists of two bismuth germanate scintillators (BGO) and an XIA LLC Digital Gamma Finder (DGF)/Pixie-4 software and card package. The spectrometer design allows a more selective measurement of (22)Na with a significant background reduction by gamma-gamma coincidence events processing. Hence, the system provides a more sensitive way to quantify trace amounts of (22)Na than normal high resolution gamma spectrometry providing a critical limit of 3 mBq within a 20 h count. The use of a list-mode data acquisition technique enabled simultaneous determination of (22)Na and (7)Be activity concentrations using a single measurement by coincidence and anticoincidence mode respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Simulated and measured neutron/gamma light output distribution for poly-energetic neutron/gamma sources

    NASA Astrophysics Data System (ADS)

    Hosseini, S. A.; Zangian, M.; Aghabozorgi, S.

    2018-03-01

    In the present paper, the light output distribution due to poly-energetic neutron/gamma (neutron or gamma) source was calculated using the developed MCNPX-ESUT-PE (MCNPX-Energy engineering of Sharif University of Technology-Poly Energetic version) computational code. The simulation of light output distribution includes the modeling of the particle transport, the calculation of scintillation photons induced by charged particles, simulation of the scintillation photon transport and considering the light resolution obtained from the experiment. The developed computational code is able to simulate the light output distribution due to any neutron/gamma source. In the experimental step of the present study, the neutron-gamma discrimination based on the light output distribution was performed using the zero crossing method. As a case study, 241Am-9Be source was considered and the simulated and measured neutron/gamma light output distributions were compared. There is an acceptable agreement between the discriminated neutron/gamma light output distributions obtained from the simulation and experiment.

  14. A novel liquid-Xenon detector concept for combined fast-neutrons and gamma imaging and spectroscopy

    NASA Astrophysics Data System (ADS)

    Breskin, A.; Israelashvili, I.; Cortesi, M.; Arazi, L.; Shchemelinin, S.; Chechik, R.; Dangendorf, V.; Bromberger, B.; Vartsky, D.

    2012-06-01

    A new detector concept is presented for combined imaging and spectroscopy of fast-neutrons and gamma rays. It comprises a liquid-Xenon (LXe) converter and scintillator coupled to a UV-sensitive gaseous imaging photomultiplier (GPM). Radiation imaging is obtained by localization of the scintillation-light from LXe with the position-sensitive GPM. The latter comprises a cascade of Thick Gas Electron Multipliers (THGEM), where the first element is coated with a CsI UV-photocathode. We present the concept and provide first model-simulation results of the processes involved and the expected performances of a detector having a LXe-filled capillaries converter. The new detector concept has potential applications in combined fast-neutron and gamma-ray screening of hidden explosives and fissile materials with pulsed sources.

  15. Bismuth- and lithium-loaded plastic scintillators for gamma and neutron detection

    DOE PAGES

    Cherepy, Nerine J.; Sanner, Robert D.; Beck, Patrick R.; ...

    2015-01-09

    In this paper, transparent plastic scintillators based on polyvinyltoluene (PVT) have been fabricated with high loading of bismuth carboxylates for gamma spectroscopy, and with lithium carboxylates for neutron detection. When activated with a combination of standard fluors, 2,5-diphenyloxazole (PPO) and tetraphenylbutadiene (TPB), gamma light yields with 15 wt% bismuth tripivalate of 5000 Ph/MeV are measured. A PVT plastic formulation including 30 wt% lithium pivalate and 30 wt% PPO offers both pulse shape discrimination, and a neutron capture peak at ~400 keVee. Finally, in another configuration, a bismuth-loaded PVT plastic is coated with ZnS( 6Li) paint, permitting simultaneous gamma and neutronmore » detection via pulse shape discrimination with a figure-of-merit of 3.8, while offering gamma spectroscopy with energy resolution of R(662 keV)=15%.« less

  16. A new measurement of the rare decay eta -> pi^0 gamma gamma with the Crystal Ball/TAPS detectors at the Mainz Microtron

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nefkens, B M; Prakhov, S; Aguar-Bartolom��, P

    2014-08-01

    A new measurement of the rare, doubly radiative decay eta->pi^0 gamma gamma was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the dependence of the partial decay width, Gamma(eta->pi^0 gamma gamma), on the two-photon invariant mass squared, m^2(gamma gamma), as well as a new, more precise value for the decay width, Gamma(eta->pi^0 gamma gamma) = (0.33+/-0.03_tot) eV, are based on analysis of 1.2 x 10^3 eta->pi^0 gamma gamma decays from a total of 6 x 10^7 eta mesons produced in the gamma p -> etamore » p reaction. The present results for dGamma(eta->pi^0 gamma gamma)/dm^2(gamma gamma) are in good agreement with previous measurements and recent theoretical calculations for this dependence.« less

  17. Systematic Effects on Duration Measurements of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Koshut, Thomas M.; Paciesas, William S.; Kouveliotou, Chryssa; vanParadijs, Jan; Pendleton, Geoffrey N.; Fishman, Gerald J.; Meegan, Charles A.

    1996-01-01

    The parameters T(sub 90) and T(sub 50) have recently been introduced as a measurement of the duration of gamma-ray bursts. We present here a description of the method of measuring T(sub 90) and T(sub 50) and its application to gamma-ray bursts observed with the Burst and Transient Source Experiment (BATSE) onboard the Compton Gamma-Ray Observatory (CGRO). We use simulated as well as observed time profiles to address some of the possible systematic effects affecting individual T(sub 90) (T(sub 50)) measurements. We show that these systematic effects do not mimic those effects that would result from time dilation if the burst sources are at distances of several Gpc. We discuss the impact of these systematic effects on the T(sub 90) (T(sub 50)) distributions for the gamma-ray bursts observed with BATSE. We distinguish between various types of T(sub 90) (T(sub 50)) distributions, and discuss the ways in which distributions observed with different experiments can vary, even though the measurements for commonly observed bursts may be the same. We then discuss the distributions observed with BATSE and compare them to those observed with other experiments.

  18. Measurement of background gamma radiation in the northern Marshall Islands.

    PubMed

    Bordner, Autumn S; Crosswell, Danielle A; Katz, Ainsley O; Shah, Jill T; Zhang, Catherine R; Nikolic-Hughes, Ivana; Hughes, Emlyn W; Ruderman, Malvin A

    2016-06-21

    We report measurements of background gamma radiation levels on six islands in the northern Marshall Islands (Enewetak, Medren, and Runit onEnewetak Atoll; Bikini and Nam on Bikini Atoll; and Rongelap on Rongelap Atoll). Measurable excess radiation could be expected from the decay of (137)Cs produced by the US nuclear testing program there from 1946 to 1958. These recordings are of relevance to safety of human habitation and resettlement. We find low levels of gamma radiation for the settled island of Enewetak [mean = 7.6 millirem/year (mrem/y) = 0.076 millisievert/year (mSv/y)], larger levels of gamma radiation for the island of Rongelap (mean = 19.8 mrem/y = 0.198 mSv/y), and relatively high gamma radiation on the island of Bikini (mean = 184 mrem/y = 1.84 mSv/y). Distributions of gamma radiation levels are provided, and hot spots are discussed. We provide interpolated maps for four islands (Enewetak, Medren, Bikini, and Rongelap), and make comparisons to control measurements performed on the island of Majuro in the southern Marshall Islands, measurements made in Central Park in New York City, and the standard agreed upon by the United States and the Republic of the Marshall Islands (RMI) governments (100 mrem/y = 1 mSv/y). External gamma radiation levels on Bikini Island significantly exceed this standard (P = <0.01), and external gamma radiation levels on the other islands are below the standard. To determine conclusively whether these islands are safe for habitation, radiation exposure through additional pathways such as food ingestion must be considered.

  19. Measurement of background gamma radiation in the northern Marshall Islands

    PubMed Central

    Bordner, Autumn S.; Crosswell, Danielle A.; Katz, Ainsley O.; Shah, Jill T.; Zhang, Catherine R.; Nikolic-Hughes, Ivana; Hughes, Emlyn W.; Ruderman, Malvin A.

    2016-01-01

    We report measurements of background gamma radiation levels on six islands in the northern Marshall Islands (Enewetak, Medren, and Runit onEnewetak Atoll; Bikini and Nam on Bikini Atoll; and Rongelap on Rongelap Atoll). Measurable excess radiation could be expected from the decay of 137Cs produced by the US nuclear testing program there from 1946 to 1958. These recordings are of relevance to safety of human habitation and resettlement. We find low levels of gamma radiation for the settled island of Enewetak [mean = 7.6 millirem/year (mrem/y) = 0.076 millisievert/year (mSv/y)], larger levels of gamma radiation for the island of Rongelap (mean = 19.8 mrem/y = 0.198 mSv/y), and relatively high gamma radiation on the island of Bikini (mean = 184 mrem/y = 1.84 mSv/y). Distributions of gamma radiation levels are provided, and hot spots are discussed. We provide interpolated maps for four islands (Enewetak, Medren, Bikini, and Rongelap), and make comparisons to control measurements performed on the island of Majuro in the southern Marshall Islands, measurements made in Central Park in New York City, and the standard agreed upon by the United States and the Republic of the Marshall Islands (RMI) governments (100 mrem/y = 1 mSv/y). External gamma radiation levels on Bikini Island significantly exceed this standard (P = <<0.01), and external gamma radiation levels on the other islands are below the standard. To determine conclusively whether these islands are safe for habitation, radiation exposure through additional pathways such as food ingestion must be considered. PMID:27274073

  20. High resolution X- and gamma-ray spectroscopy of solar flares

    NASA Technical Reports Server (NTRS)

    Lin, R. P.

    1984-01-01

    A balloon-borne X- and gamma-ray instrument was developed, fabricated, and flown. This instrument has the highest energy resolution of any instrument flown to date for measurements of solar and cosmic X-ray and gamma-ray emission in the 13 to 600 keV energy range. The purpose of the solar measurements was to study electron acceleration and solar flare energy release processes. The cosmic observations were to search for cyclotron line features from neutron stars and for low energy gamma-ray lines from nucleosynthesis. The instrument consists of four 4 cm diameter, 1.3 cm thick, planar intrinsic germanium detectors cooled by liquid nitrogen and surrounded by CsI and NaI anti-coincidence scintillation crystals. A graded z collimator limited the field of view to 3 deg x 6 deg and a gondola pointing system provided 0.3 deg pointing accuracy. A total of four flights were made with this instrument. Additional funding was obtained from NSF for the last three flights, which had primarily solar objectives. A detailed instrument description is given. The main scientific results and the data analysis are discussed. Current work and indications for future work are summarized. A bibliography of publications resulting from this work is given.

  1. DETECTION OF FREE RADICALS IN FATS IRRADIATED WITH $gamma$-RAYS BY MEANS OF ELECTRON SPIN RESONANCE SPECTROSCOPY (in German)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lueck, H.; Deffner, U.; Kohn, R.

    1963-10-01

    Electron spin resonance (ESR) spectroscopy offers a convenient method for determining the occurrence of free radicals in food products irradiated with gamma rays. Some work has been done on meat and vegetables, but nothing on fats. For this reason, lard, tallow, and cocoa butter were irradiated at --196, --80, 0, and +30 deg C with 1, 2, and 10 Mrad gamma rays at a rate of 0.5 Mrad/hr and measured the ESR spectra at --196, --80 deg C, and at room temperature allowing various times to elapse between irradiation and measurement. The spectra were taken with a Varian V 4500more » spectrometer at a modulation of 100 kHz. In all the examined fats, free radicals were found after irradiation with high doses at very low temperatures. The number of free radicals was very small and their life duration varied at room temperature between fractions of a minute and several weeks. The spectra of the fats investigated were very similar, although their life duration varied depending on the presence of impurities which acted as radical scavengers. When the irradiated fats were stored for some time at room temperature, free peroxide radicals were found. (OID)« less

  2. Monitoring of the interconversion of gamma-butyrolactone (GBL) to gamma hydroxybutyric acid (GHB) by Raman spectroscopy.

    PubMed

    Munshi, Tasnim; Brewster, Victoria L; Edwards, Howell G M; Hargreaves, Michael D; Jilani, Shelina K; Scowen, Ian J

    2013-08-01

    Gamma-hydroxybutyric acid (GHB) is a drug-of-abuse that has recently become associated with drug-facilitated sexual assault, known as date rape. For this reason the drug is commonly found 'spiked' in alcoholic beverages. When GHB is in solution it may undergo conversion into the corresponding lactone, Gamma-butyrolactone (GBL). Studies have been carried out to determine the detection limits of GHB and GBL in various solutions by Raman spectroscopy and to monitor the interconversion of GHB and GBL in solution with different pH conditions and temperature. In this study, a portable Raman spectrometer was used to study the interconversion of GHB and GBL in water and ethanol solutions as a function of pH, time, and temperature. The aim of this was to determine the optimum pH range for conversion in order to relate this to the pH ranges that the drug is likely to be subjected to, first in spiked beverages and secondly after ingestion in the digestive system. The aim was also to identify a timescale for this conversion in relation to possible scenarios, for example if GHB takes a number of hours to convert to GBL, it is likely for the beverage to be ingested before esterification can take place. GHB and GBL were then spiked into a selection of beverages of known pH in order to study the stability of GHB and GBL in real systems. Copyright © 2012 John Wiley & Sons, Ltd.

  3. Consistent Small-Sample Variances for Six Gamma-Family Measures of Ordinal Association

    ERIC Educational Resources Information Center

    Woods, Carol M.

    2009-01-01

    Gamma-family measures are bivariate ordinal correlation measures that form a family because they all reduce to Goodman and Kruskal's gamma in the absence of ties (1954). For several gamma-family indices, more than one variance estimator has been introduced. In previous research, the "consistent" variance estimator described by Cliff and…

  4. Thallium Bromide as an Alternative Material for Room-Temperature Gamma-Ray Spectroscopy and Imaging

    NASA Astrophysics Data System (ADS)

    Koehler, William

    Thallium bromide is an attractive material for room-temperature gamma-ray spectroscopy and imaging because of its high atomic number (Tl: 81, Br: 35), high density (7.56 g/cm3), and a wide bandgap (2.68 eV). In this work, 5 mm thick TlBr detectors achieved 0.94% FWHM at 662 keV for all single-pixel events and 0.72% FWHM at 662 keV from the best pixel and depth using three-dimensional position sensing technology. However, these results were limited to stable operation at -20°C. After days to months of room-temperature operation, ionic conduction caused these devices to fail. Depth-dependent signal analysis was used to isolate room-temperature degradation effects to within 0.5 mm of the anode surface. This was verified by refabricating the detectors after complete failure at room temperature; after refabrication, similar performance and functionality was recovered. As part of this work, the improvement in electron drift velocity and energy resolution during conditioning at -20°C was quantified. A new method was developed to measure the impurity concentration without changing the gamma ray measurement setup. The new method was used to show that detector conditioning was likely the result of charged impurities drifting out of the active volume. This space charge reduction then caused a more stable and uniform electric field. Additionally, new algorithms were developed to remove hole contributions in high-hole-mobility detectors to improve depth reconstruction. These algorithms improved the depth reconstruction (accuracy) without degrading the depth uncertainty (precision). Finally, spectroscopic and imaging performance of new 11 x 11 pixelated-anode TlBr detectors was characterized. The larger detectors were used to show that energy resolution can be improved by identifying photopeak events from their Tl characteristic x-rays.

  5. Lu1-xI3:Cex--A Scintillator for gamma ray spectroscopy and time-of-flight PET

    DOEpatents

    Shah, Kanai S [Newton, MA

    2009-03-17

    The present invention concerns very fast scintillator materials comprising lutetium iodide doped with Cerium Lu.sub.1-xI.sub.3:Ce.sub.x; LuI.sub.3:Ce). The LuI.sub.3 scintillator material has surprisingly good characteristics including high light output, high gamma ray stopping efficiency, fast response, low cost, good proportionality, and minimal afterglow that the material is useful for gamma ray spectroscopy, medical imaging, nuclear and high energy physics research, diffraction, non-destructive testing, nuclear treaty verification and safeguards, and geological exploration. The timing resolution of the scintillators of the present invention provide compositions capable of resolving the position of an annihilation event within a portion of a human body cross-section.

  6. Gamma-Ray Spectroscopy at TRIUMF-ISAC: the New Frontier of Radioactive Ion Beam Research

    NASA Astrophysics Data System (ADS)

    Ball, G. C.; Andreoiu, C.; Austin, R. A. E.; Bandyopadhyay, D.; Becker, J. A.; Bricault, P.; Brown, N.; Chan, S.; Churchman, R.; Colosimo, S.; Coombes, H.; Cross, D.; Demand, G.; Drake, T. E.; Dombsky, M.; Ettenauer, S.; Finlay, P.; Furse, D.; Garnsworthy, A.; Garrett, P. E.; Green, K. L.; Grinyer, G. F.; Hyland, B.; Hackman, G.; Kanungo, R.; Kulp, W. D.; Lassen, J.; Leach, K. G.; Leslie, J. R.; Mattoon, C.; Melconian, D.; Morton, A. C.; Pearson, C. J.; Phillips, A. A.; Rand, E.; Sarazin, F.; Svensson, C. E.; Sumithrarachchi, S.; Schumaker, M. A.; Triambak, S.; Waddington, J. C.; Walker, P. M.; Williams, S. J.; Wood, J. L.; Wong, J.; Zganjar, E. F.

    2009-03-01

    High-resolution gamma-ray spectroscopy is essential to fully exploit the unique scientific opportunities at the next generation radioactive ion beam facilities such as the TRIUMF Isotope Separator and Accelerator (ISAC). At ISAC the 8π spectrometer and its associated auxiliary detectors is optimize for β-decay studies while TIGRESS an array of segmented clover HPGe detectors has been designed for studies with accelerated beams. This paper gives a brief overview of these facilities and also presents recent examples of the diverse experimental program carried out at the 8π spectrometer.

  7. Measurements of the $$\\mathrm{ pp \\to W \\gamma\\gamma }$$ and $$\\mathrm{ pp \\to Z \\gamma\\gamma }$$ cross sections and limits on anomalous quartic gauge couplings at $$\\sqrt{s} =$$ 8 TeV

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sirunyan, A. M.; Tumasyan, A.; Adam, W.

    Here, measurements are presented ofmore » $$ \\mathrm{ W \\gamma\\gamma } $$ and $$ \\mathrm{ Z \\gamma\\gamma } $$ production in proton-proton collisions. Fiducial cross sections are reported based on a data sample corresponding to an integrated luminosity of 19.4 fb$$^{-1}$$ collected with the CMS detector at a center-of-mass energy of 8 TeV. Signal is identified through the $$\\mathrm{ W } \\to \\ell\

  8. Measurements of the $$\\mathrm{ pp \\to W \\gamma\\gamma }$$ and $$\\mathrm{ pp \\to Z \\gamma\\gamma }$$ cross sections and limits on anomalous quartic gauge couplings at $$\\sqrt{s} =$$ 8 TeV

    DOE PAGES

    Sirunyan, A. M.; Tumasyan, A.; Adam, W.; ...

    2017-10-11

    Here, measurements are presented ofmore » $$ \\mathrm{ W \\gamma\\gamma } $$ and $$ \\mathrm{ Z \\gamma\\gamma } $$ production in proton-proton collisions. Fiducial cross sections are reported based on a data sample corresponding to an integrated luminosity of 19.4 fb$$^{-1}$$ collected with the CMS detector at a center-of-mass energy of 8 TeV. Signal is identified through the $$\\mathrm{ W } \\to \\ell\

  9. Moisture effect in prompt gamma measurements from soil samples.

    PubMed

    Naqvi, A A; Khiari, F Z; Liadi, F A; Khateeb-Ur-Rehman; Raashid, M A; Isab, A H

    2016-09-01

    The variation in intensity of 1.78MeV silicon, 6.13MeV oxygen, and 2.22MeV hydrogen prompt gamma rays from soil samples due to the addition of 5.1, 7.4, 9.7, 11.9 and 14.0wt% water was studied for 14MeV incident neutron beams utilizing a LaBr3:Ce gamma ray detector. The intensities of 1.78MeV and 6.13MeV gamma rays from silicon and oxygen, respectively, decreased with increasing sample moisture. The intensity of 2.22MeV hydrogen gamma rays increases with moisture. The decrease in intensity of silicon and oxygen gamma rays with moisture concentration indicates a loss of 14MeV neutron flux, while the increase in intensity of 2.22MeV gamma rays with moisture indicates an increase in thermal neutron flux due to increasing concentration of moisture. The experimental intensities of silicon, oxygen and hydrogen prompt gamma rays, measured as a function of moisture concentration in the soil samples, are in good agreement with the theoretical results obtained through Monte Carlo calculations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Factors influencing in situ gamma-ray measurements

    NASA Astrophysics Data System (ADS)

    Loonstra, E. H.; van Egmond, F. M.

    2009-04-01

    Introduction In situ passive gamma-ray sensors are very well suitable for mapping physical soil properties. In order to make a qualitative sound soil map, high quality input parameters for calibration are required. This paper will focus on the factors that affect the output of in situ passive gamma-ray sensors, the primary source, soil, not taken into account. Factors The gamma-ray spectrum contains information of naturally occurring nuclides 40K, 238U and 232Th and man-made nuclides like 137Cs, as well as the total count rate. Factors that influence the concentration of these nuclides and the count rate can be classified in 3 categories. These are sensor design, environmental conditions and operational circumstances. Sensor design The main elements of an in situ gamma-ray sensor that influence the outcome and quality of the output are the crystal and the spectrum analysis method. Material and size of the crystal determine the energy resolution. Though widely used, NaI crystals are not the most efficient capturer of gamma radiation. Alternatives are BGO and CsI. BGO has a low peak resolution, which prohibits use in cases where man-made nuclides are subject of interest. The material is expensive and prone to temperature instability. CsI is robust compared to NaI and BGO. The density of CsI is higher than NaI, yielding better efficiency, especially for smaller crystal sizes. More volume results in higher energy efficiency. The reduction of the measured spectral information into concentration of radionuclides is mostly done using the Windows analysis method. In Windows, the activities of the nuclides are found by summing the intensities of the spectrum found in a certain interval surrounding a peak. A major flaw of the Windows method is the limited amount of spectral information that is incorporated into the analysis. Another weakness is the inherent use of ‘stripping factors' to account for contributions of radiation from nuclide A into the peak of nuclide B. This

  11. Lu.sub.1-xI.sub.3:Ce.sub.x-a scintillator for gamma-ray spectroscopy and time-of-flight pet

    DOEpatents

    Shah, Kanai S [Newton, MA

    2008-02-12

    The present invention includes very fast scintillator materials including lutetium iodide doped with Cerium (Lu.sub.1-xI.sub.3:Ce.sub.x; LuI.sub.3:Ce). The LuI.sub.3 scintillator material has surprisingly good characteristics including high light output, high gamma-ray stopping efficiency, fast response, low cost, good proportionality, and minimal afterglow that the material is useful for gamma-ray spectroscopy, medical imaging, nuclear and high energy physics research, diffraction, non-destructive testing, nuclear treaty verification and safeguards, and geological exploration.

  12. Neutron and gamma dose and spectra measurements on the Little Boy replica

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hoots, S.; Wadsworth, D.

    1984-06-01

    The radiation-measurement team of the Weapons Engineering Division at Lawrence Livermore National Laboratory (LLNL) measured neutron and gamma dose and spectra on the Little Boy replica at Los Alamos National Laboratory (LANL) in April 1983. This assembly is a replica of the gun-type atomic bomb exploded over Hiroshima in 1945. These measurements support the National Academy of Sciences Program to reassess the radiation doses due to atomic bomb explosions in Japan. Specifically, the following types of information were important: neutron spectra as a function of geometry, gamma to neutron dose ratios out to 1.5 km, and neutron attenuation in themore » atmosphere. We measured neutron and gamma dose/fission from close-in to a kilometer out, and neutron and gamma spectra at 90 and 30/sup 0/ close-in. This paper describes these measurements and the results. 12 references, 13 figures, 5 tables.« less

  13. Modeled Martian subsurface elemental composition measurements with the Probing In situ with Neutron and Gamma ray instrument: Gamma and Neutron Measurements on Mars

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nowicki, Suzanne F.; Evans, Larry G.; Starr, Richard D.

    Here, the Probing In situ with Neutrons and Gamma rays (PING) instrument is an innovative application of active neutron-induced gamma-ray technology. The objective of PING is to measure the elemental composition of the Martian regolith. As part 2 of a two-part submission, this manuscript presents PING's sensitivities as a function of the Martian regolith depth and PING's uncertainties in the measurements as a function of observation time in passive and active mode. Part 1 of our submission models the associated regolith types. The modeled sensitivities show that in PING's active mode, where both a Pulsed Neutron Generator (PNG) and amore » Gamma-Ray Spectrometer (GRS) are used, PING can interrogate the material below the rover to about 20 cm due to the penetrating nature of the high-energy neutrons and the resulting secondary gamma rays observed with the GRS. PING is capable of identifying most major and minor rock-forming elements, including H, O, Na, Mn, Mg, Al, Si, P, S, Cl, Cr, K, Ca, Ti, Fe and Th. The modeled uncertainties show that PING's use of a PNG reduces the required observation times by an order of magnitude over a passive operating mode where the PNG is turned off. While the active mode allows for more complete elemental inventories with higher sensitivity, the gamma-ray signatures of some elements are strong enough to detect in passive mode. We show that PING can detect changes in key marker elements and make thermal neutron measurements in about 1 minute that are sensitive to H and Cl.« less

  14. Modeled Martian subsurface elemental composition measurements with the Probing In situ with Neutron and Gamma ray instrument: Gamma and Neutron Measurements on Mars

    DOE PAGES

    Nowicki, Suzanne F.; Evans, Larry G.; Starr, Richard D.; ...

    2017-02-01

    Here, the Probing In situ with Neutrons and Gamma rays (PING) instrument is an innovative application of active neutron-induced gamma-ray technology. The objective of PING is to measure the elemental composition of the Martian regolith. As part 2 of a two-part submission, this manuscript presents PING's sensitivities as a function of the Martian regolith depth and PING's uncertainties in the measurements as a function of observation time in passive and active mode. Part 1 of our submission models the associated regolith types. The modeled sensitivities show that in PING's active mode, where both a Pulsed Neutron Generator (PNG) and amore » Gamma-Ray Spectrometer (GRS) are used, PING can interrogate the material below the rover to about 20 cm due to the penetrating nature of the high-energy neutrons and the resulting secondary gamma rays observed with the GRS. PING is capable of identifying most major and minor rock-forming elements, including H, O, Na, Mn, Mg, Al, Si, P, S, Cl, Cr, K, Ca, Ti, Fe and Th. The modeled uncertainties show that PING's use of a PNG reduces the required observation times by an order of magnitude over a passive operating mode where the PNG is turned off. While the active mode allows for more complete elemental inventories with higher sensitivity, the gamma-ray signatures of some elements are strong enough to detect in passive mode. We show that PING can detect changes in key marker elements and make thermal neutron measurements in about 1 minute that are sensitive to H and Cl.« less

  15. Measurements of the Martian Gamma/Neutron Spectra with MSL/RAD

    NASA Astrophysics Data System (ADS)

    Kohler, J.; Zeitlin, C. J.; Ehresmann, B.; Wimmer-Schweingruber, R. F.; Hassler, D.; Reitz, G.; Brinza, D.; Weigle, E.; Boettcher, S.; Burmeister, S.; Guo, J.; Martin-Garcia, C.; Boehm, E.; Posner, A.; Rafkin, S. C.; Kortmann, O.

    2013-12-01

    The Radiation Assessment Detector (RAD) onboard Mars Science Laboratory's rover curiosity measures the energetic charged and neutral particle spectra and the radiation dose rate on the Martian surface. An important factor for determining the biological impact of the Martian surface radiation is the specific contribution of neutrons, which possess a high biological effectiveness. In contrast to charged particles, neutrons and gamma rays are generally only measured indirectly. Their measurement is the result of a complex convolution of the incident particle spectrum with the measurement process. We apply an inversion method to calculate the gamma/neutron spectra from the RAD neutral particle measurements. Here we show first measurements of the Martian gamma/neutron spectra and compare them to theoretical predictions. We find that the shape of the gamma spectrum is very similar to the predicted one, but with a ~50% higher intensity. The measured neutron spectrum agrees well with prediction up to ~100 MeV, but shows a considerably increased intensity for higher energies. The measured neutron spectrum translates into a radiation dose rate of 25 μGy/day and a dose equivalent rate of 106 μSv/day. This corresponds to 10% of the total surface dose rate, and 15% of the biological relevant surface dose equivalent rate on Mars. Measuring the Martian neutron spectra is an essential step for determining the mutagenic influences to past or present life at or beneath the Martian surface as well as the radiation hazard for future human exploration, including the shielding design of a potential habitat. The contribution of neutrons to the dose equivalent increases considerably with shielding thickness, so our measurements provide an important figure to mitigate cancer risk.

  16. Isomer-delayed gamma-ray spectroscopy of neutron-rich 166Tb

    NASA Astrophysics Data System (ADS)

    Gurgi, L. A.; Regan, P. H.; Söderström, P.-A.; Watanabe, H.; Walker, P. M.; Podolyák, Zs.; Nishimura, S.; Berry, T. A.; Doornenbal, P.; Lorusso, G.; Isobe, T.; Baba, H.; Xu, Z. Y.; Sakurai, H.; Sumikama, T.; Catford, W. N.; Bruce, A. M.; Browne, F.; Lane, G. J.; Kondev, F. G.; Odahara, A.; Wu, J.; Liu, H. L.; Xu, F. R.; Korkulu, Z.; Lee, P.; Liu, J. J.; Phong, V. H.; Yagi, A.; Zhang, G. X.; Alharbi, T.; Carroll, R. J.; Chae, K. Y.; Dombradi, Zs.; Estrade, A.; Fukuda, N.; Griffin, C.; Ideguchi, E.; Inabe, N.; Kanaoka, H.; Kojouharov, I.; Kubo, T.; Kubono, S.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lee, E. J.; Lee, C. S.; Lotay, G.; Moon, C. B.; Nishizuka, I.; Nita, C. R.; Patel, Z.; Roberts, O. J.; Schaffner, H.; Shand, C. M.; Suzuki, H.; Takeda, H.; Terashima, S.; Vajta, Zs.; Kanaya, S.; Valiente-Dobòn, J. J.

    2017-09-01

    This short paper presents the identification of a metastable, isomeric-state decay in the neutron-rich odd-odd, prolate-deformed nucleus 166Tb. The nucleus of interest was formed using the in-flight fission of a 345 MeV per nucleon 238U primary beam at the RIBF facility, RIKEN, Japan. Gamma-ray transitions decaying from the observed isomeric states in 166Tb were identified using the EURICA gamma-ray spectrometer, positioned at the final focus of the BigRIPS fragments separator. The current work identifies a single discrete gamma-ray transition of energy 119 keV which de-excites an isomeric state in 166Tb with a measured half-life of 3.5(4) μs. The multipolarity assignment for this transition is an electric dipole and is made on the basis internal conversion and decay lifetime arguments. Possible two quasi-particle Nilsson configurations for the initial and final states which are linked by this transition in 166Tb are made on the basis of comparison with Blocked BCS Nilsson calculations, with the predicted ground state configuration for this nucleus arising from the coupling of the v(1-/2)?[521] and ? π(3+/2) Nilsson orbitals.

  17. Comparison of the effect of plasma treatment and gamma ray irradiation on PS-Cu nanocomposite films surface

    NASA Astrophysics Data System (ADS)

    Farag, O. F.

    2018-06-01

    Polystyrene-copper (PS-Cu) nanocomposite films were treated with DC N2 plasma and gamma rays irradiations. The plasma treatment of PS-Cu film surface was carried out at different treatment times, gas pressure 0.4 Torr and the applied power 3.5 W. On the other hand, the treatment with gamma rays irradiation were carried out at irradiation doses 10, 30 and 50 kGy. The induced changes in surface properties of PS-Cu films were investigated with UV-viss spectroscopy, scanning electron microscopy (SEM) and FTIR spectroscopy techniques. In addition, the wettability property, surface free energy, spreading coefficient and surface roughness of the treated samples were studied by measuring the contact angle. The UV-viss spectroscopy analysis revealed that the optical band gap decreases with increasing the treatment time and the irradiation dose for plasma and gamma treatments, respectively. SEM observations showed that the particle size of copper particles was increased with increasing the treatment time and the irradiation dose, but gamma treatment changes the copper particles size from nano scale to micro scale. The contact angle measurements showing that the wettability property, surface free energy, spreading coefficient and surface roughness of the treated PS-Cu samples were increased remarkably with increasing the treatment time and the irradiation dose for plasma and gamma treatments, respectively. The contact angle, surface free energy, spreading coefficient and surface roughness of the treated PS-Cu samples are more influenced by plasma treatment than gamma treatment.

  18. Field gamma-ray spectrometer GS256: measurements stability

    NASA Astrophysics Data System (ADS)

    Mojzeš, Andrej

    2009-01-01

    The stability of in situ readings of the portable gamma-ray spectrometer GS256 during the field season of 2006 was studied. The instrument is an impulse detector of gamma rays based on NaI(Tl) 3" × 3" scintillation unit and 256-channel spectral analyzer which allows simultaneous assessment of up to 8 radioisotopes in rocks. It is commonly used in surface geophysical survey for the measurement of natural 40K, 238U and 232Th but also artificial 137Cs quantities. The statistical evaluation is given of both repeated measurements - in the laboratory and at several field control points in different survey areas. The variability of values shows both the instrument stability and also the relative influence of some meteorological factors, mainly rainfalls. The analysis shows an acceptable level of instrument measurements stability, the necessity to avoid measurement under unfavourable meteorological conditions and to keep detailed field book information about time, position and work conditions.

  19. Fermi Large Area Telescope Measurements of the Diffuse Gamma-Ray Emission at Intermediate Galactic Latitudes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Abdo, A.A.; /Naval Research Lab, Wash., D.C.; Ackermann, M.

    The diffuse galactic {gamma}-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess {gamma}-ray emission {ge}1 GeV relative to diffuse galactic {gamma}-ray emission models consistent with directly measured CR spectra (the so-called 'EGRET GeV excess'). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse {gamma}-ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes 10{sup o}more » {le} |b| {le} 20{sup o}. The LAT spectrum for this region of the sky is well reproduced by a diffuse galactic {gamma}-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.« less

  20. Fermi large area telescope measurements of the diffuse gamma-ray emission at intermediate galactic latitudes.

    PubMed

    Abdo, A A; Ackermann, M; Ajello, M; Anderson, B; Atwood, W B; Axelsson, M; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Baughman, B M; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Burnett, T H; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cecchi, C; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Dereli, H; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; Di Bernardo, G; Dormody, M; do Couto e Silva, E; Drell, P S; Dubois, R; Dumora, D; Edmonds, Y; Farnier, C; Favuzzi, C; Fegan, S J; Focke, W B; Frailis, M; Fukazawa, Y; Funk, S; Fusco, P; Gaggero, D; Gargano, F; Gehrels, N; Germani, S; Giebels, B; Giglietto, N; Giordano, F; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M-H; Grove, J E; Guillemot, L; Guiriec, S; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hughes, R E; Jóhannesson, G; Johnson, A S; Johnson, R P; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kawai, N; Kerr, M; Knödlseder, J; Kocian, M L; Kuehn, F; Kuss, M; Lande, J; Latronico, L; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Mazziotta, M N; McConville, W; McEnery, J E; Meurer, C; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nolan, P L; Nuss, E; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ormes, J F; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Razzano, M; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Rodriguez, A Y; Roth, M; Ryde, F; Sadrozinski, H F-W; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Sellerholm, A; Sgrò, C; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Starck, J-L; Stecker, F W; Striani, E; Strickman, M S; Strong, A W; Suson, D J; Tajima, H; Takahashi, H; Tanaka, T; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Vasileiou, V; Vilchez, N; Vitale, V; Waite, A P; Wang, P; Winer, B L; Wood, K S; Ylinen, T; Ziegler, M

    2009-12-18

    The diffuse galactic gamma-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess gamma-ray emission greater, > or approximately equal to 1 GeV relative to diffuse galactic gamma-ray emission models consistent with directly measured CR spectra (the so-called "EGRET GeV excess"). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse gamma-ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes 10 degrees < or = |b| < or = 20 degrees. The LAT spectrum for this region of the sky is well reproduced by a diffuse galactic gamma-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.

  1. Resonance production in. gamma gamma. collisions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Renard, F.M.

    1983-04-01

    The processes ..gamma gamma.. ..-->.. hadrons can be depicted as follows. One photon creates a q anti q pair which starts to evolve; the other photon can either (A) make its own q anti q pair and the (q anti q q anti q) system continue to evolve or (B) interact with the quarks of the first pair and lead to a modified (q anti q) system in interaction with C = +1 quantum numbers. A review of the recent theoretical activity concerning resonance production and related problems is given under the following headings: hadronic C = +1 spectroscopy (qmore » anti q, qq anti q anti q, q anti q g, gg, ggg bound states and mixing effects); exclusive ..gamma gamma.. processes (generalities, unitarized Born method, VDM and QCD); total cross section (soft and hard contributions); q/sup 2/ dependence of soft processes (soft/hard separation, 1/sup +- +/ resonances); and polarization effects. (WHK)« less

  2. PWR and BWR spent fuel assembly gamma spectra measurements

    NASA Astrophysics Data System (ADS)

    Vaccaro, S.; Tobin, S. J.; Favalli, A.; Grogan, B.; Jansson, P.; Liljenfeldt, H.; Mozin, V.; Hu, J.; Schwalbach, P.; Sjöland, A.; Trellue, H.; Vo, D.

    2016-10-01

    A project to research the application of nondestructive assay (NDA) to spent fuel assemblies is underway. The research team comprises the European Atomic Energy Community (EURATOM), embodied by the European Commission, DG Energy, Directorate EURATOM Safeguards; the Swedish Nuclear Fuel and Waste Management Company (SKB); two universities; and several United States national laboratories. The Next Generation of Safeguards Initiative-Spent Fuel project team is working to achieve the following technical goals more easily and efficiently than in the past using nondestructive assay measurements of spent fuel assemblies: (1) verify the initial enrichment, burnup, and cooling time of facility declaration; (2) detect the diversion or replacement of pins, (3) estimate the plutonium mass, (4) estimate the decay heat, and (5) determine the reactivity of spent fuel assemblies. This study focuses on spectrally resolved gamma-ray measurements performed on a diverse set of 50 assemblies [25 pressurized water reactor (PWR) assemblies and 25 boiling water reactor (BWR) assemblies]; these same 50 assemblies will be measured with neutron-based NDA instruments and a full-length calorimeter. Given that encapsulation/repository and dry storage safeguards are the primarily intended applications, the analysis focused on the dominant gamma-ray lines of 137Cs, 154Eu, and 134Cs because these isotopes will be the primary gamma-ray emitters during the time frames of interest to these applications. This study addresses the impact on the measured passive gamma-ray signals due to the following factors: burnup, initial enrichment, cooling time, assembly type (eight different PWR and six different BWR fuel designs), presence of gadolinium rods, and anomalies in operating history. To compare the measured results with theory, a limited number of ORIGEN-ARP simulations were performed.

  3. PWR and BWR spent fuel assembly gamma spectra measurements

    DOE PAGES

    Vaccaro, S.; Tobin, Stephen J.; Favalli, Andrea; ...

    2016-07-17

    A project to research the application of nondestructive assay (NDA) to spent fuel assemblies is underway. The research team comprises the European Atomic Energy Community (EURATOM), embodied by the European Commission, DG Energy, Directorate EURATOM Safeguards; the Swedish Nuclear Fuel and Waste Management Company (SKB); two universities; and several United States national laboratories. The Next Generation of Safeguards Initiative–Spent Fuel project team is working to achieve the following technical goals more easily and efficiently than in the past using nondestructive assay measurements of spent fuel assemblies: (1) verify the initial enrichment, burnup, and cooling time of facility declaration; (2) detectmore » the diversion or replacement of pins, (3) estimate the plutonium mass, (4) estimate the decay heat, and (5) determine the reactivity of spent fuel assemblies. This study focuses on spectrally resolved gamma-ray measurements performed on a diverse set of 50 assemblies [25 pressurized water reactor (PWR) assemblies and 25 boiling water reactor (BWR) assemblies]; these same 50 assemblies will be measured with neutron-based NDA instruments and a full-length calorimeter. Given that encapsulation/repository and dry storage safeguards are the primarily intended applications, the analysis focused on the dominant gamma-ray lines of 137Cs, 154Eu, and 134Cs because these isotopes will be the primary gamma-ray emitters during the time frames of interest to these applications. This study addresses the impact on the measured passive gamma-ray signals due to the following factors: burnup, initial enrichment, cooling time, assembly type (eight different PWR and six different BWR fuel designs), presence of gadolinium rods, and anomalies in operating history. As a result, to compare the measured results with theory, a limited number of ORIGEN-ARP simulations were performed.« less

  4. PWR and BWR spent fuel assembly gamma spectra measurements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vaccaro, S.; Tobin, Stephen J.; Favalli, Andrea

    A project to research the application of nondestructive assay (NDA) to spent fuel assemblies is underway. The research team comprises the European Atomic Energy Community (EURATOM), embodied by the European Commission, DG Energy, Directorate EURATOM Safeguards; the Swedish Nuclear Fuel and Waste Management Company (SKB); two universities; and several United States national laboratories. The Next Generation of Safeguards Initiative–Spent Fuel project team is working to achieve the following technical goals more easily and efficiently than in the past using nondestructive assay measurements of spent fuel assemblies: (1) verify the initial enrichment, burnup, and cooling time of facility declaration; (2) detectmore » the diversion or replacement of pins, (3) estimate the plutonium mass, (4) estimate the decay heat, and (5) determine the reactivity of spent fuel assemblies. This study focuses on spectrally resolved gamma-ray measurements performed on a diverse set of 50 assemblies [25 pressurized water reactor (PWR) assemblies and 25 boiling water reactor (BWR) assemblies]; these same 50 assemblies will be measured with neutron-based NDA instruments and a full-length calorimeter. Given that encapsulation/repository and dry storage safeguards are the primarily intended applications, the analysis focused on the dominant gamma-ray lines of 137Cs, 154Eu, and 134Cs because these isotopes will be the primary gamma-ray emitters during the time frames of interest to these applications. This study addresses the impact on the measured passive gamma-ray signals due to the following factors: burnup, initial enrichment, cooling time, assembly type (eight different PWR and six different BWR fuel designs), presence of gadolinium rods, and anomalies in operating history. As a result, to compare the measured results with theory, a limited number of ORIGEN-ARP simulations were performed.« less

  5. Continuous versus pulse neutron induced gamma spectroscopy for soil carbon analysis

    USDA-ARS?s Scientific Manuscript database

    Neutron induced gamma spectra analysis (NGA) provides a means of measuring carbon in large soil volumes without destructive sampling. Calibration of the NGA system must account for system background and the interference of other nuclei on the carbon peak at 4.43 MeV. Accounting for these factors pro...

  6. Isomer-delayed gamma-ray spectroscopy of neutron-rich 166Tb

    DOE PAGES

    Gurgi, L. A.; Regan, P. H.; Söderström, P. -A.; ...

    2017-09-13

    Here, this short paper presents the identification of a metastable, isomeric-state decay in the neutron-rich odd-odd, prolate-deformed nucleus 166Tb. The nucleus of interest was formed using the in-flight fission of a 345 MeV per nucleon 238U primary beam at the RIBF facility, RIKEN, Japan. Gamma-ray transitions decaying from the observed isomeric states in 166Tb were identified using the EURICA gamma-ray spectrometer, positioned at the final focus of the BigRIPS fragments separator. The current work identifies a single discrete gamma-ray transition of energy 119 keV which de-excites an isomeric state in 166Tb with a measured half-life of 3.5(4) μs. The multipolaritymore » assignment for this transition is an electric dipole and is made on the basis internal conversion and decay lifetime arguments. Possible two quasi-particle Nilsson configurations for the initial and final states which are linked by this transition in 166Tb are made on the basis of comparison with Blocked BCS Nilsson calculations, with the predicted ground state configuration for this nucleus arising from the coupling of the v(1-/2)[521] and π(3+/2) Nilsson orbitals.« less

  7. The influence of exogenous conditions on mobile measured gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Dierke, C.; Werban, U.; Dietrich, P.

    2012-12-01

    In the past, gamma ray measurements have been used for geological surveys and exploration using airborne and borehole logging systems. For these applications, the relationships between the measured physical parameter - the concentration of natural gamma emitters 40K, 238U and 232Th - and geological origin or sedimentary developments are well described. Based on these applications and knowledge in combination with adjusted sensor systems, gamma ray measurements are used to derive soil parameters to create detailed soil maps e.g., in digital soil mapping (DSM) and monitoring of soils. Therefore, not only qualitative but also quantitative comparability is necessary. Grain size distribution, type of clay minerals and organic matter content are soil parameters which directly influence the gamma ray emitter concentration. Additionally, the measured concentration is influenced by endogenous processes like soil moisture variation due to raining events, foggy weather conditions, or erosion and deposition of material. A time series of gamma ray measurements was used to observe changes in gamma ray concentration on a floodplain area in Central Germany. The study area is characterised by high variations in grain size distribution and occurrence of flooding events. For the survey, we used a 4l NaI(Tl) detector with GPS connection mounted on a sledge, which is towed across the field sites by a four-wheel-vehicle. The comparison of data from different time steps shows similar structures with minor variation between the data ranges and shape of structures. However, the data measured during different soil moisture contents differ in absolute value. An average increase of soil moisture of 36% leads to a decrease of Th (by 20%), K (by 29%), and U (by 41%). These differences can be explained by higher attenuation of radiation during higher soil moisture content. The different changes in nuclide concentration will also lead to varying ratios. We will present our experiences concerning

  8. Using gamma-ray emission to measure areal density of inertial confinement fusion capsulesa)

    NASA Astrophysics Data System (ADS)

    Hoffman, N. M.; Wilson, D. C.; Herrmann, H. W.; Young, C. S.

    2010-10-01

    Fusion neutrons streaming from a burning inertial confinement fusion capsule generate gamma rays via inelastic nuclear scattering in the ablator of the capsule. The intensity of gamma-ray emission is proportional to the product of the ablator areal density (ρR) and the yield of fusion neutrons, so by detecting the gamma rays we can infer the ablator areal density, provided we also have a measurement of the capsule's total neutron yield. In plastic-shell capsules, for example, C12 nuclei emit gamma rays at 4.44 MeV after excitation by 14.1 MeV neutrons from D+T fusion. These gamma rays can be measured by a new gamma-ray detector under development. Analysis of predicted signals is in progress, with results to date indicating that the method promises to be useful for diagnosing imploded capsules.

  9. Exploring atmospheric radon with airborne gamma-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Baldoncini, Marica; Albéri, Matteo; Bottardi, Carlo; Minty, Brian; Raptis, Kassandra G. C.; Strati, Virginia; Mantovani, Fabio

    2017-12-01

    222Rn is a noble radioactive gas produced along the 238U decay chain, which is present in the majority of soils and rocks. As 222Rn is the most relevant source of natural background radiation, understanding its distribution in the environment is of great concern for investigating the health impacts of low-level radioactivity and for supporting regulation of human exposure to ionizing radiation in modern society. At the same time, 222Rn is a widespread atmospheric tracer whose spatial distribution is generally used as a proxy for climate and pollution studies. Airborne gamma-ray spectroscopy (AGRS) always treated 222Rn as a source of background since it affects the indirect estimate of equivalent 238U concentration. In this work the AGRS method is used for the first time for quantifying the presence of 222Rn in the atmosphere and assessing its vertical profile. High statistics radiometric data acquired during an offshore survey are fitted as a superposition of a constant component due to the experimental setup background radioactivity plus a height dependent contribution due to cosmic radiation and atmospheric 222Rn. The refined statistical analysis provides not only a conclusive evidence of AGRS 222Rn detection but also a (0.96 ± 0.07) Bq/m3 222Rn concentration and a (1318 ± 22) m atmospheric layer depth fully compatible with literature data.

  10. Transparent ceramic scintillators for gamma spectroscopy and MeV imaging

    NASA Astrophysics Data System (ADS)

    Cherepy, N. J.; Seeley, Z. M.; Payne, S. A.; Swanberg, E. L.; Beck, P. R.; Schneberk, D. J.; Stone, G.; Perry, R.; Wihl, B.; Fisher, S. E.; Hunter, S. L.; Thelin, P. A.; Thompson, R. R.; Harvey, N. M.; Stefanik, T.; Kindem, J.

    2015-09-01

    We report on the development of two new mechanically rugged, high light yield transparent ceramic scintillators: (1) Ce-doped Gd-garnet for gamma spectroscopy, and (2) Eu-doped Gd-Lu-bixbyite for radiography. GYGAG(Ce) garnet transparent ceramics offer ρ = 5.8g/cm3, Zeff = 48, principal decay of <100 ns, and light yield of 50,000 Ph/MeV. Gdgarnet ceramic scintillators offer the best energy resolution of any oxide scintillator, as good as R(662 keV) = 3% (Si-PD readout) for small sizes and typically R(662 keV) < 5% for cubic inch sizes. For radiography, the bixbyite transparent ceramic scintillator, (Gd,Lu,Eu)2O3, or "GLO," offers excellent x-ray stopping, with ρ = 9.1 g/cm3 and Zeff = 68. Several 10" diameter by 0.1" thickness GLO scintillators have been fabricated. GLO outperforms scintillator glass for high energy radiography, due to higher light yield (55,000 Ph/MeV) and better stopping, while providing spatial resolution of >8 lp/mm.

  11. A triple-crystal phoswich detector with digital pulse shape discrimination for alpha/beta/gamma spectroscopy

    NASA Astrophysics Data System (ADS)

    White, Travis L.; Miller, William H.

    1999-02-01

    Researchers at the University of Missouri - Columbia have developed a three-crystal phoswich detector coupled to a digital pulse shape discrimination system for use in alpha/beta/gamma spectroscopy. Phoswich detectors use a sandwich of scintillators viewed by a single photomultiplier tube to simultaneously detect multiple types of radiation. Separation of radiation types is based upon pulse shape difference among the phosphors, which has historically been performed with analog circuitry. The system uses a GaGe CompuScope 1012, 12 bit, 10 MHz computer-based oscilloscope that digitally captures the pulses from a phoswich detector and subsequently performs pulse shape discrimination with cross-correlation analysis. The detector, based partially on previous phoswich designs by Usuda et al., uses a 10 mg/cm 2 thick layer of ZnS(Ag) for alpha detection, followed by a 0.254 cm CaF 2(Eu) crystal for beta detection, all backed by a 2.54 cm NaI(Tl) crystal for gamma detection. Individual energy spectra and count rate information for all three radiation types are displayed and updated periodically. The system shows excellent charged particle discrimination with an accuracy of greater than 99%. Future development will include a large area beta probe with gamma-ray discrimination, systems for low-energy photon detection (e.g. Bremsstrahlung or keV-range photon emissions), and other health physics instrumentation.

  12. Metallic scattering lifetime measurements with terahertz time-domain spectroscopy

    NASA Astrophysics Data System (ADS)

    Lea, Graham Bryce

    The momentum scattering lifetime is a fundamental parameter of metallic conduction that can be measured with terahertz time-domain spectroscopy. This technique has an important strength over optical reflectance spectroscopy: it is capable of measuring both the phase and the amplitude of the probing radiation. This allows simultaneous, independent measurements of the scattering lifetime and resistivity. Broadly, it is the precision of the phase measurement that determines the precision of scattering lifetime measurements. This thesis describes milliradian-level phase measurement refinements in the experimental technique and measures the conductivity anisotropy in the correlated electron system CaRuO3. These phase measurement refinements translate to femtosecond-level refinements in scattering lifetime measurements of thin metallic films. Keywords: terahertz time-domain spectroscopy, calcium ruthenate, ruthenium oxides, correlated electrons, experimental technique.

  13. Determining the solar-flare photospheric scale height from SMM gamma-ray measurements

    NASA Technical Reports Server (NTRS)

    Lingenfelter, Richard E.

    1991-01-01

    A connected series of Monte Carlo programs was developed to make systematic calculations of the energy, temporal and angular dependences of the gamma-ray line and neutron emission resulting from such accelerated ion interactions. Comparing the results of these calculations with the Solar Maximum Mission/Gamma Ray Spectrometer (SMM/GRS) measurements of gamma-ray line and neutron fluxes, the total number and energy spectrum of the flare-accelerated ions trapped on magnetic loops at the Sun were determined and the angular distribution, pitch angle scattering, and mirroring of the ions on loop fields were constrained. Comparing the calculations with measurements of the time dependence of the neutron capture line emission, a determination of the He-3/H ratio in the photosphere was also made. The diagnostic capabilities of the SMM/GRS measurements were extended by developing a new technique to directly determine the effective photospheric scale height in solar flares from the neutron capture gamma-ray line measurements, and critically test current atmospheric models in the flare region.

  14. A reanalysis of radioisotope measurements of the $^9$Be$$(\\gamma,n)^8$$Be cross-section

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Robinson, Alan E.

    Themore » $^9$Be$$(\\gamma,n)^8$$Be reaction is enhanced by a near threshold $1/2^+$ state. Contradictions between existing measurements of this reaction cross-section affect calculations of astrophysical r-process yields, dark matter detector calibrations, and the theory of the nuclear structure of $^9$Be. Select well-documented radioisotope $^9$Be$$(\\gamma,n)$$ source yield measurements have been reanalyzed, providing a set of high-accuracy independently measured cross sections. A Breit-Wigner fit of these corrected measurements yields $$E_R=1738.8\\pm1.9$$ keV, $$\\Gamma_\\gamma=0.771\\pm0.021$$ eV, and $$\\Gamma_n=268\\pm15$$ keV for the $1/2^+$ state. A virtual $1/2^+$ state is excluded with 99.3\\% confidence.« less

  15. A reanalysis of radioisotope measurements of the $^9$Be$$(\\gamma,n)^8$$Be cross-section

    DOE PAGES

    Robinson, Alan E.

    2016-02-18

    Themore » $^9$Be$$(\\gamma,n)^8$$Be reaction is enhanced by a near threshold $1/2^+$ state. Contradictions between existing measurements of this reaction cross-section affect calculations of astrophysical r-process yields, dark matter detector calibrations, and the theory of the nuclear structure of $^9$Be. Select well-documented radioisotope $^9$Be$$(\\gamma,n)$$ source yield measurements have been reanalyzed, providing a set of high-accuracy independently measured cross sections. A Breit-Wigner fit of these corrected measurements yields $$E_R=1738.8\\pm1.9$$ keV, $$\\Gamma_\\gamma=0.771\\pm0.021$$ eV, and $$\\Gamma_n=268\\pm15$$ keV for the $1/2^+$ state. A virtual $1/2^+$ state is excluded with 99.3\\% confidence.« less

  16. Polycrystalline gamma plutonium's elastic moduli versus temperature

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Migliori, Albert; Betts, J; Trugman, A

    2009-01-01

    Resonant ultrasound spectroscopy was used to measure the elastic properties of pure polycrystalline {sup 239}Pu in the {gamma} phase. Shear and longitudinal elastic moduli were measured simultaneously and the bulk modulus was computed from them. A smooth, linear, and large decrease of all elastic moduli with increasing temperature was observed. They calculated the Poisson ratio and found that it increases from 0.242 at 519 K to 0.252 at 571 K. These measurements on extremely well characterized pure Pu are in agreement with other reported results where overlap occurs.

  17. Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics

    PubMed Central

    Tanimori, Toru; Mizumura, Yoshitaka; Takada, Atsushi; Miyamoto, Shohei; Takemura, Taito; Kishimoto, Tetsuro; Komura, Shotaro; Kubo, Hidetoshi; Kurosawa, Shunsuke; Matsuoka, Yoshihiro; Miuchi, Kentaro; Mizumoto, Tetsuya; Nakamasu, Yuma; Nakamura, Kiseki; Parker, Joseph D.; Sawano, Tatsuya; Sonoda, Shinya; Tomono, Dai; Yoshikawa, Kei

    2017-01-01

    Since the discovery of nuclear gamma-rays, its imaging has been limited to pseudo imaging, such as Compton Camera (CC) and coded mask. Pseudo imaging does not keep physical information (intensity, or brightness in Optics) along a ray, and thus is capable of no more than qualitative imaging of bright objects. To attain quantitative imaging, cameras that realize geometrical optics is essential, which would be, for nuclear MeV gammas, only possible via complete reconstruction of the Compton process. Recently we have revealed that “Electron Tracking Compton Camera” (ETCC) provides a well-defined Point Spread Function (PSF). The information of an incoming gamma is kept along a ray with the PSF and that is equivalent to geometrical optics. Here we present an imaging-spectroscopic measurement with the ETCC. Our results highlight the intrinsic difficulty with CCs in performing accurate imaging, and show that the ETCC surmounts this problem. The imaging capability also helps the ETCC suppress the noise level dramatically by ~3 orders of magnitude without a shielding structure. Furthermore, full reconstruction of Compton process with the ETCC provides spectra free of Compton edges. These results mark the first proper imaging of nuclear gammas based on the genuine geometrical optics. PMID:28155870

  18. Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics.

    PubMed

    Tanimori, Toru; Mizumura, Yoshitaka; Takada, Atsushi; Miyamoto, Shohei; Takemura, Taito; Kishimoto, Tetsuro; Komura, Shotaro; Kubo, Hidetoshi; Kurosawa, Shunsuke; Matsuoka, Yoshihiro; Miuchi, Kentaro; Mizumoto, Tetsuya; Nakamasu, Yuma; Nakamura, Kiseki; Parker, Joseph D; Sawano, Tatsuya; Sonoda, Shinya; Tomono, Dai; Yoshikawa, Kei

    2017-02-03

    Since the discovery of nuclear gamma-rays, its imaging has been limited to pseudo imaging, such as Compton Camera (CC) and coded mask. Pseudo imaging does not keep physical information (intensity, or brightness in Optics) along a ray, and thus is capable of no more than qualitative imaging of bright objects. To attain quantitative imaging, cameras that realize geometrical optics is essential, which would be, for nuclear MeV gammas, only possible via complete reconstruction of the Compton process. Recently we have revealed that "Electron Tracking Compton Camera" (ETCC) provides a well-defined Point Spread Function (PSF). The information of an incoming gamma is kept along a ray with the PSF and that is equivalent to geometrical optics. Here we present an imaging-spectroscopic measurement with the ETCC. Our results highlight the intrinsic difficulty with CCs in performing accurate imaging, and show that the ETCC surmounts this problem. The imaging capability also helps the ETCC suppress the noise level dramatically by ~3 orders of magnitude without a shielding structure. Furthermore, full reconstruction of Compton process with the ETCC provides spectra free of Compton edges. These results mark the first proper imaging of nuclear gammas based on the genuine geometrical optics.

  19. Optimizing a three-stage Compton camera for measuring prompt gamma rays emitted during proton radiotherapy

    PubMed Central

    Peterson, S W; Robertson, D; Polf, J

    2011-01-01

    In this work, we investigate the use of a three-stage Compton camera to measure secondary prompt gamma rays emitted from patients treated with proton beam radiotherapy. The purpose of this study was (1) to develop an optimal three-stage Compton camera specifically designed to measure prompt gamma rays emitted from tissue and (2) to determine the feasibility of using this optimized Compton camera design to measure and image prompt gamma rays emitted during proton beam irradiation. The three-stage Compton camera was modeled in Geant4 as three high-purity germanium detector stages arranged in parallel-plane geometry. Initially, an isotropic gamma source ranging from 0 to 15 MeV was used to determine lateral width and thickness of the detector stages that provided the optimal detection efficiency. Then, the gamma source was replaced by a proton beam irradiating a tissue phantom to calculate the overall efficiency of the optimized camera for detecting emitted prompt gammas. The overall calculated efficiencies varied from ~10−6 to 10−3 prompt gammas detected per proton incident on the tissue phantom for several variations of the optimal camera design studied. Based on the overall efficiency results, we believe it feasible that a three-stage Compton camera could detect a sufficient number of prompt gammas to allow measurement and imaging of prompt gamma emission during proton radiotherapy. PMID:21048295

  20. Nuclear Deexcitation Gamma Ray Lines from Accelerated Particle Interactions

    DTIC Science & Technology

    2002-01-01

    MeV) 10−1 1 10 102 103 104 105 C ou nt s s− 1 M eV −1 neutron capture 12C 56Fe, 24Mg, 20Ne, 28Si 16O 16O, 15N positron annihilation Fig. 1.— Gamma...1996). The results of these efforts have established gamma-ray spectroscopy as an important tool for exploration of high-energy processes in solar...Murphy et al. 1997) is shown in Figure 1. Among the main results of the investigations using gamma-ray spectroscopy are (1) the determination of the

  1. A limit on the diffuse gamma-rays measured with KASCADE-Grande

    NASA Astrophysics Data System (ADS)

    Kang, D.; Apel, W. D.; Arteaga-Velázquez, J. C.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Feng, Z.; Fuhrmann, D.; Gherghel-Lascu, A.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huber, D.; Huege, T.; Kampert, K. H.; Klages, H. O.; Link, K.; Łuczak, P.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Oehlschläger, J.; Ostapchenko, S.; Palmieri, N.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schoo, S.; Schröder, F.; Sima, O.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Weindl, A.; Wochele, J.; Zabierowski, J.

    2015-08-01

    Using data measured by the KASCADE-Grande air shower array, an upper limit to the flux of ultra-high energy gamma-rays in the primary cosmic-ray flux is determined. KASCADE-Grande measures the electromagnetic and muonic components for individual air showers in the energy range from 10 PeV up to 1 EeV. The analysis is performed by selecting air showers with low muon contents. A preliminary result on the 90% C.L. upper limit to the relative intensity of gamma-ray with respect to cosmic ray primaries is presented and compared with limits reported by other measurements.

  2. Beta- and gamma-dose measurements of the Godiva IV critical assembly.

    PubMed

    Hankins, D E

    1984-03-01

    To aid in the re-evaluation of an exposure that occurred in 1963, information was required on the response of film badges to the beta- and gamma-ray doses from a critical assembly. Of particular interest was the beta spectra from the assembly. The techniques used and the results obtained in this study are of interest to health physicists at facilities where exposures to betas occur. The dose rates from the Los Alamos National Laboratory Godiva IV Critical Assembly were measured at numerous distances from the assembly four and 12 days following a burst. Information was obtained on the beta-particle spectra using absorption curve studies. The beta/gamma dose-rate ratio as a function of distance from the assembly was determined. Shielding provided by various metals, gloves and clothing was measured. The beta- and gamma-ray doses measured were compared with a film packet used in the past at the Nevada Test Site with two types of current TLD personnel badges. Measurements made with a commercial thin-window ion chamber instrument are compared with the dose rates obtained using other dosimeters.

  3. Radiation measurement above the lunar surface by Kaguya gamma-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Hasebe, Nobuyuki; Nagaoka, Hiroshi; Kusano, Hiroki; Hareyama, Matoko; Ideguchi, Yusuke; Shimizu, Sota; Shibamura, Eido

    The lunar surface is filled with various ionizing radiations such as high energy galactic particles, albedo particles and secondary radiations of neutrons, gamma rays and other elementary particles. A high-resolution Kaguya Gamma-Ray Spectrometer (KGRS) was carried on the Japan’s lunar explorer SELENE (Kaguya), the largest lunar orbiter since the Apollo missions. The KGRS instrument employed, for the first time in lunar exploration, a high-purity Ge crystal to increase the identification capability of elemental gamma-ray lines. The Ge detector is surrounded by BGO and plastic counters as for anticoincidence shields. The KGRS measured gamma rays in the energy range from 200 keV to 13 MeV with high precision to determine the chemical composition of the lunar surface. It provided data on the abundance of major elements over the entire lunar surface. In addition to the gamma-ray observation by the KGRS, it successfully measured the global distribution of fast neutrons. In the energy spectra of gamma-rays observed by the KGRS, several saw-tooth- peaks of Ge are included, which are formed by the collision interaction of lunar fast neutrons with Ge atoms in the Ge crystal. With these saw-tooth-peaks analysis, global distribution of neutrons emitted from the lunara surface was successfully created, which was compared with the previous results obtained by Lunar Prospector neutron maps. Another anticoincidence counter, the plastic counter with 5 mm thickness, was used to veto radiation events mostly generated by charged particles. A single photomultiplier serves to count scintillation light from the plastic scintillation counter. The global map of counting rates observed by the plastic counter was also created, implying that the radiation counting rate implies the geological distribution, in spite that the plastic counter mostly measures high energy charged particles and energetic neutrons. These results are presented and discussed.

  4. Measurement of the Branching Fraction of the Exclusive Decay B0 --> K*0gamma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Barrera, Barbara

    The b {yields} s{gamma} transition proceeds by a loop penguin diagram. It may be used to measure precisely the couplings of the top quark and to search for the effects of any new particles appearing in the loop. We present a preliminary measurement of the branching fraction of the exclusive decay, B{sup 0} {yields} K*{sup 0}{gamma}. They use 8.6 x 10{sup 6} B{bar B} decays to measure B(B{sup 0} {yields} K*{sup 0}{gamma}) = (5.4 {+-} 0.8 {+-} 0.5) x 10{sup -5}.

  5. Conversion-electron spectroscopy and gamma-gamma angular correlation measurements in 116Sn

    NASA Astrophysics Data System (ADS)

    Cross, D. S.; Pore, J. L.; Andreoiu, C.; Ball, G. C.; Bender, P. C.; Chester, A. S.; Churchman, R.; Demand, G. A.; Diaz Varela, A.; Dunlop, R.; Garnsworthy, A. B.; Garrett, P. E.; Hackman, G.; Hadinia, B.; Jigmeddorj, B.; Laffoley, A. T.; Liblong, A.; Kanungo, R.; Miller, D. T.; Noakes, B.; Petrache, C. M.; Starosta, K.; Svensson, C. E.; Voss, P.; Wang, Z.-M.; Wilson, J. M.; Wood, J. L.; Yates, S. W.

    2017-11-01

    The 116Sn nucleus was studied via the β- decay of 116In utilizing the 8π spectrometer and its auxiliary detectors at TRIUMF-ISAC. The resulting K-shell conversion coefficients, K/L ratios, and multipole mixing ratios are presented. The 23+ → 21+ 931 keV and 22+ → 21+ 819 keV transition mixing ratios were re-measured and found to be δ = +1.8_{-0.5}^{+0.7} and -1.83(8), respectively. Newly measured mixing ratios for transitions among the low-lying I^{π} = 4+ states in 116Sn, when combined with γ-ray intensity data, suggest that the 2529 keV 42+ state possesses a neutron broken-pair admixture in addition to its dominant proton 2p-2h component.

  6. GABA level, gamma oscillation, and working memory performance in schizophrenia

    PubMed Central

    Chen, Chi-Ming A.; Stanford, Arielle D.; Mao, Xiangling; Abi-Dargham, Anissa; Shungu, Dikoma C.; Lisanby, Sarah H.; Schroeder, Charles E.; Kegeles, Lawrence S.

    2014-01-01

    A relationship between working memory impairment, disordered neuronal oscillations, and abnormal prefrontal GABA function has been hypothesized in schizophrenia; however, in vivo GABA measurements and gamma band neural synchrony have not yet been compared in schizophrenia. This case–control pilot study (N = 24) compared baseline and working memory task-induced neuronal oscillations acquired with high-density electroencephalograms (EEGs) to GABA levels measured in vivo with magnetic resonance spectroscopy. Working memory performance, baseline GABA level in the left dorsolateral prefrontal cortex (DLPFC), and measures of gamma oscillations from EEGs at baseline and during a working memory task were obtained. A major limitation of this study is a relatively small sample size for several analyses due to the integration of diverse methodologies and participant compliance. Working memory performance was significantly lower for patients than for controls. During the working memory task, patients (n = 7) had significantly lower amplitudes in gamma oscillations than controls (n = 9). However, both at rest and across working memory stages, there were significant correlations between gamma oscillation amplitude and left DLPFC GABA level. Peak gamma frequency during the encoding stage of the working memory task (n = 16) significantly correlated with GABA level and working memory performance. Despite gamma band amplitude deficits in patients across working memory stages, both baseline and working memory-induced gamma oscillations showed strong dependence on baseline GABA levels in patients and controls. These findings suggest a critical role for GABA function in gamma band oscillations, even under conditions of system and cognitive impairments as seen in schizophrenia. PMID:24749063

  7. GABA level, gamma oscillation, and working memory performance in schizophrenia.

    PubMed

    Chen, Chi-Ming A; Stanford, Arielle D; Mao, Xiangling; Abi-Dargham, Anissa; Shungu, Dikoma C; Lisanby, Sarah H; Schroeder, Charles E; Kegeles, Lawrence S

    2014-01-01

    A relationship between working memory impairment, disordered neuronal oscillations, and abnormal prefrontal GABA function has been hypothesized in schizophrenia; however, in vivo GABA measurements and gamma band neural synchrony have not yet been compared in schizophrenia. This case-control pilot study (N = 24) compared baseline and working memory task-induced neuronal oscillations acquired with high-density electroencephalograms (EEGs) to GABA levels measured in vivo with magnetic resonance spectroscopy. Working memory performance, baseline GABA level in the left dorsolateral prefrontal cortex (DLPFC), and measures of gamma oscillations from EEGs at baseline and during a working memory task were obtained. A major limitation of this study is a relatively small sample size for several analyses due to the integration of diverse methodologies and participant compliance. Working memory performance was significantly lower for patients than for controls. During the working memory task, patients (n = 7) had significantly lower amplitudes in gamma oscillations than controls (n = 9). However, both at rest and across working memory stages, there were significant correlations between gamma oscillation amplitude and left DLPFC GABA level. Peak gamma frequency during the encoding stage of the working memory task (n = 16) significantly correlated with GABA level and working memory performance. Despite gamma band amplitude deficits in patients across working memory stages, both baseline and working memory-induced gamma oscillations showed strong dependence on baseline GABA levels in patients and controls. These findings suggest a critical role for GABA function in gamma band oscillations, even under conditions of system and cognitive impairments as seen in schizophrenia.

  8. The possibility of gamma-ray astronomy measurements on the Russian segment of the International Space Station.

    NASA Astrophysics Data System (ADS)

    Fradkin, M. I.; Gorchakov, E. V.; Kaplin, V. A.; Kaplin, D. V.; Kurnosova, L. V.; Labenskij, A. G.; Runtso, M. F.; Topchiev, N. P.

    The conditions required for gamma-ray astronomy measurements at energies of 10 - 1000 GeV by a gamma-ray telescope on the International Space Station are discussed. It is shown that the properties of the detected gamma rays can be determined accurately at 30 - 1000 GeV, even if the space station solar arrays fall in the aperture of the gamma-ray telescope. Measurements of the secondary gamma-ray spectrum using a ground-based model of the gamma-ray telescope have been carried out, and the resulting spectrum at energies of 1 - 100 GeV is presented.

  9. Coherent Raman spectroscopy for supersonic flow measurments

    NASA Technical Reports Server (NTRS)

    She, C. Y.

    1986-01-01

    In collaboration with NASA/Langley Research Center, a truly nonintrusive and nonseeding method for measuring supersonic molecular flow parameters was proposed and developed at Colorado State University. The feasibility of this Raman Doppler Velocimetry (RDV), currently operated in a scanning mode, was demonstrated not only in a laboratory environment at Colorado State University, but also in a major wind tunnel at NASA/Langley Research Center. The research progress of the RDV development is summarized. In addition, methods of coherent Rayleigh-Brillouin spectroscopy and single-pulse coherent Raman spectroscopy are investigated, respectively, for measurements of high-pressure and turbulent flows.

  10. Insights into electron and ion acceleration and transport from x-ray and gamma-ray imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Hurford, Gordon J.; Krucker, Samuel

    The previous solar maximum has featured high resolution imaging/spectroscopy observations at hard x-ray and gamma-ray energies by the Reuven Ramaty High Energy Solar/Spectroscopic Imager (RHESSI). Highlights of these observations will be reviewed, along with their impli-cations for our understanding of ion and electron acceleration and transport processes. The results to date have included new insights into the location of the acceleration region and the thick target model, a new appreciation of the significance of x-ray albedo, observation of coronal gamma-ray sources and their implications for electron trapping, and indications of differences in the acceleration and transport between electrons and ions. The role of RHESSI's observational strengths and weaknesses in determining the character of its scientific results will also be discussed and used to identify what aspects of the acceleration and transport processes must await the next generation of instrumentation. The extent to which new instrumentation now under development, such as Solar Orbiter/STIX, GRIPS, and FOXSI, can address these open issues will be outlined.

  11. Thermally stimulated capacitance in gamma irradiated epitaxial 4H-SiC Schottky barrier diodes

    NASA Astrophysics Data System (ADS)

    Vigneshwara Raja, P.; Narasimha Murty, N. V. L.

    2018-04-01

    Deep level defects in 4H-SiC Schottky barrier diodes (SBDs) fabricated on n-type epitaxial 4H-SiC have been identified by thermally stimulated capacitance (TSCAP) spectroscopy prior to and after 60Co-gamma irradiation. The TSCAP measurements on the non-irradiated SBDs reveal two electron traps at Ec-0.63 eV (˜250 K) and Ec-1.13 eV (˜525 K), whereas only one trap at Ec-0.63 eV is identified by conventional thermally stimulated current (TSC) measurements. Hence, TSCAP spectroscopy is more effective in identifying deep level defects in epitaxial 4 H-SiC SBDs as compared to the TSC spectroscopy. Upon exposure to 60Co-gamma rays up to a dose of 100 Mrad, significant changes in the concentration of the traps at Ec-0.63 eV, Ec-1.13 eV, and one new trap at Ec-0.89 eV (˜420 K) are observed. The electrical characteristics of the SBDs are considerably changed after gamma irradiation. The dominant mechanisms responsible for the irradiation induced changes in the SBD electrical characteristics are analyzed by incorporating the trap signatures in the commercial Silvaco® TCAD device simulator. The extracted trap parameters of the irradiated SBDs may be helpful in predicting the survival of 4H-SiC SBD detectors at higher irradiation levels.

  12. New concepts for HgI2 scintillator gamma ray spectroscopy

    NASA Technical Reports Server (NTRS)

    Iwanczyk, Jan S.

    1994-01-01

    The primary goals of this project are development of the technology for HgI2 photodetectors (PD's), development of a HgI2/scintillator gamma detector, development of electronics, and development of a prototype gamma spectrometer. Work on the HgI2 PD's involved HgI2 purification and crystal growth, detector surface and electrical contact studies, PD structure optimization, encapsulation and packaging, and testing. Work on the HgI2/scintillator gamma detector involved a study of the optical - mechanical coupling for the optimization of CsI(Tl)/HgI2 gamma ray detectors and determination of the relationship between resolution versus scintillator type and size. The development of the electronics focused on low noise amplification circuits using different preamp input FET's and the use of a coincidence technique to maximize the signal, minimize the noise contribution in the gamma spectra, and improve the overall system resolution.

  13. Lu.sub.1-xI.sub.3:Ce.sub.x--a scintillator for gamma ray spectroscopy and time-of-flight PET

    DOEpatents

    Shah, Kanai S.

    2007-02-06

    The present invention concerns very fast scintillator materials comprising lutetium iodide doped with Cerium (Lu.sub.1-xI.sub.3:Ce.sub.x; LuI.sub.3:Ce). The LuI.sub.3 scintillator material has surprisingly good characteristics including high light output, high gamma ray stopping efficiency, fast response, low cost, good proportionality, and minimal afterglow that the material is useful for gamma ray spectroscopy, medical imaging, nuclear and high energy physics research, diffraction, non-destructive testing, nuclear treaty verification and safeguards, and geological exploration. The timing resolution of the scintillators of the present invention provide compositions capable of resolving the position of an annihilation event within a portion of a human body cross-section.

  14. Collimated prompt gamma TOF measurements with multi-slit multi-detector configurations

    NASA Astrophysics Data System (ADS)

    Krimmer, J.; Chevallier, M.; Constanzo, J.; Dauvergne, D.; De Rydt, M.; Dedes, G.; Freud, N.; Henriquet, P.; La Tessa, C.; Létang, J. M.; Pleskač, R.; Pinto, M.; Ray, C.; Reithinger, V.; Richard, M. H.; Rinaldi, I.; Roellinghoff, F.; Schuy, C.; Testa, E.; Testa, M.

    2015-01-01

    Longitudinal prompt-gamma ray profiles have been measured with a multi-slit multi-detector configuration at a 75 MeV/u 13C beam and with a PMMA target. Selections in time-of-flight and energy have been applied in order to discriminate prompt-gamma rays produced in the target from background events. The ion ranges which have been extracted from each individual detector module agree amongst each other and are consistent with theoretical expectations. In a separate dedicated experiment with 200 MeV/u 12C ions the fraction of inter-detector scattering has been determined to be on the 10%-level via a combination of experimental results and simulations. At the same experiment different collimator configurations have been tested and the shielding properties of tungsten and lead for prompt-gamma rays have been measured.

  15. High-Resolution Gamma-Ray Imaging Measurements Using Externally Segmented Germanium Detectors

    NASA Technical Reports Server (NTRS)

    Callas, J.; Mahoney, W.; Skelton, R.; Varnell, L.; Wheaton, W.

    1994-01-01

    Fully two-dimensional gamma-ray imaging with simultaneous high-resolution spectroscopy has been demonstrated using an externally segmented germanium sensor. The system employs a single high-purity coaxial detector with its outer electrode segmented into 5 distinct charge collection regions and a lead coded aperture with a uniformly redundant array (URA) pattern. A series of one-dimensional responses was collected around 511 keV while the system was rotated in steps through 180 degrees. A non-negative, linear least-squares algorithm was then employed to reconstruct a 2-dimensional image. Corrections for multiple scattering in the detector, and the finite distance of source and detector are made in the reconstruction process.

  16. Measurement of gastric emptying by intragastric gamma scintigraphy.

    PubMed

    Malbert, C H; Mathis, C; Bobillier, E; Laplace, J P; Horowitz, M

    1997-09-01

    Gastric emptying is usually measured in animals and humans by dilution/sampling or external scintigraphy. These methods are either time consuming or require expensive equipment. The capacity of a miniature gamma counter positioned in the stomach to measure emptying of liquid and solid meals was evaluated. In eight conscious pigs fitted with gastric and duodenal cannulae, gastric emptying of saline (500 mL), dextrose (20%, 500 mL), porridge (300 g) and scrambled eggs (300 g), all labelled with 3.5 MBq 99mTC, was evaluated. When positioned in the antrum the probe was unable to quantify gastric emptying. In contrast, measurements of the fractional emptying of saline over 4-min periods by the probe positioned in the corpus and quantification of radioactivity in the duodenal effluent correlated closely (r = 0.88, P < 0.05). Gastric emptying (50% emptying time) of saline and both solid meals measured by the probe was not significantly different from quantification of the duodenal effluent volume. No difference was observed also for the dextrose meal but only while gastric acid secretion was suppressed by omeprazole. We conclude that an intragastric gamma counter permits measurement of gastric emptying of homogeneous meals provided meal stimulation of gastric secretion was not extensive. This was possible probably by monitoring emptying from the proximal stomach.

  17. Measurement of the branching ratio of a rare decay {eta}{yields}{pi}{sup 0}{gamma}{gamma} with WASA-at-COSY

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lalwani, Kavita

    2011-10-24

    In this paper we present the preliminary results on the measurement of the branching ratio of a rare decay {eta}{yields}{pi}{sup 0}{gamma}{gamma} with the WASA Detector at COSY. We have used a sample of 10{sup 7}{eta} mesons produced at the COSY ring using the pd{yields}{sup 3}He{eta} reaction close to threshold. We detail the intricate extraction of the signal, which has about 360{+-}70(stat){eta}{yields}{pi}{sup 0}{gamma}{gamma} events, from the overwhelming background channels for example {eta}{yields}3{pi}{sup 0}, pd{yields}{sup 3}He 3{pi}{sup 0} and pd{yields}{sup 3}He 2{pi}{sup 0}.

  18. Gamma-ray dosimetry measurements of the Little Boy replica

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Plassmann, E.A.; Pederson, R.A.

    1984-01-01

    We present the current status of our gamma-ray dosimetry results for the Little Boy replica. Both Geiger-Mueller and thermoluminescent detectors were used in the measurements. Future work is needed to test assumptions made in data analysis.

  19. Gamma irradiation effect on the chemical composition and the antioxidant activity of Ipomoea batatas L.

    NASA Astrophysics Data System (ADS)

    Tahir, D.; Halide, H.; Wahab, A. W.; Kurniawan, D.

    2014-09-01

    The chemical composition and antioxidant activity of Ipomoea batatas L. (sweet potato) were studied by x-ray fluorescence (XRF) spectroscopy, Fourier transform infrared spectroscopy, and by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity. The irradiation treatment was performed by using Cs-137 as a gamma sources in experimental equipment. Treatment by irradiation emerges as a possible conservation technique that has been tested successfully in several food products. The amount of chemical composition was changed and resulting new chemical for absorbed dose 40 mSv. Interestingly, it was found that gamma irradiation significantly increased the antioxidant activity, as measured by DPPH radical scavenging capacity. The antioxidant activity of Ipomoea batatas L. extract was dramatically increased in the non-irradiated sample to the sample irradiated at 40 mSv. These results indicate that gamma irradiation of Ipomoea batatas L. extract can enhance its antioxidant activity through the formation of a new chemical compound. Based on these results, increased antioxidant activity of Ipomoea batatas L. extracts by gamma rays can be applied to various industries, especially cosmetics, foodstuffs, and pharmaceuticals.

  20. Fission products detection in irradiated TRIGA fuel by means of gamma spectroscopy and MCNP calculation.

    PubMed

    Cagnazzo, M; Borio di Tigliole, A; Böck, H; Villa, M

    2018-05-01

    Aim of this work was the detection of fission products activity distribution along the axial dimension of irradiated fuel elements (FEs) at the TRIGA Mark II research reactor of the Technische Universität (TU) Wien. The activity distribution was measured by means of a customized fuel gamma scanning device, which includes a vertical lifting system to move the fuel rod along its vertical axis. For each investigated FE, a gamma spectrum measurement was performed along the vertical axis, with steps of 1 cm, in order to determine the axial distribution of the fission products. After the fuel elements underwent a relatively short cooling down period, different fission products were detected. The activity concentration was determined by calibrating the gamma detector with a standard calibration source of known activity and by MCNP6 simulations for the evaluation of self-absorption and geometric effects. Given the specific TRIGA fuel composition, a correction procedure is developed and used in this work for the measurement of the fission product Zr 95 . This measurement campaign is part of a more extended project aiming at the modelling of the TU Wien TRIGA reactor by means of different calculation codes (MCNP6, Serpent): the experimental results presented in this paper will be subsequently used for the benchmark of the models developed with the calculation codes. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. About cosmic gamma ray lines

    NASA Astrophysics Data System (ADS)

    Diehl, Roland

    2017-06-01

    Gamma ray lines from cosmic sources convey the action of nuclear reactions in cosmic sites and their impacts on astrophysical objects. Gamma rays at characteristic energies result from nuclear transitions following radioactive decays or high-energy collisions with excitation of nuclei. The gamma-ray line from the annihilation of positrons at 511 keV falls into the same energy window, although of different origin. We present here the concepts of cosmic gamma ray spectrometry and the corresponding instruments and missions, followed by a discussion of recent results and the challenges and open issues for the future. Among the lessons learned are the diffuse radioactive afterglow of massive-star nucleosynthesis in 26Al and 60Fe gamma rays, which is now being exploited towards the cycle of matter driven by massive stars and their supernovae; large interstellar cavities and superbubbles have been recognised to be of key importance here. Also, constraints on the complex processes making stars explode as either thermonuclear or core-collapse supernovae are being illuminated by gamma-ray lines, in this case from shortlived radioactivities from 56Ni and 44Ti decays. In particular, the three-dimensionality and asphericities that have recently been recognised as important are enlightened in different ways through such gamma-ray line spectroscopy. Finally, the distribution of positron annihilation gamma ray emission with its puzzling bulge-dominated intensity disctribution is measured through spatially-resolved spectra, which indicate that annihilation conditions may differ in different parts of our Galaxy. But it is now understood that a variety of sources may feed positrons into the interstellar medium, and their characteristics largely get lost during slowing down and propagation of positrons before annihilation; a recent microquasar flare was caught as an opportunity to see positrons annihilate at a source.

  2. Improved detector for the measurement of gamma radiation

    NASA Astrophysics Data System (ADS)

    Zelt, F. B.

    1985-07-01

    The present invention lies in the field of gamma ray spectrometry of geologic deposits and other materials, such as building materials (cement, asphalt, etc.) More specifically, the invention is an improved device for the gamma ray spetcrometery of gelogical deposits as a tool for petroleum exploration, geologic research and monitoring of radio-active materials such as in uranium mill tailings and the like. Improvement consists in enlarging the area of the receptor face and without any necessarily substantial increase in the volume of the receptor crystal over the current cylindrical shapes. The invention also provides, as a corollary of the increase in area receptor crystal face, a reduction in the weight of the amount of material necessary to provide effective shielding of the crystal from atmospheric radiation and radiation from deposits not under examination. The area of the receptor crystal face is increased by forming the crystal as a truncated cone with the shielding shaped as a hollow frustrum of a cone. A photomultiplier device is secured to the smaller face of the crystal. The improved detector shape can also be used in scintillometers which measure total gamma radiation.

  3. Ultra-High Rate Measurements of Spent Fuel Gamma-Ray Emissions

    NASA Astrophysics Data System (ADS)

    Rodriguez, Douglas; Vandevender, Brent; Wood, Lynn; Glasgow, Brian; Taubman, Matthew; Wright, Michael; Dion, Michael; Pitts, Karl; Runkle, Robert; Campbell, Luke; Fast, James

    2014-03-01

    Presently there are over 200,000 irradiated spent nuclear fuel (SNF) assemblies in the world, each containing a concerning amount of weapons-usable material. Both facility operators and safeguards inspectors want to improve composition determination. Current measurements are expensive and difficult so new methods are developed through models. Passive measurements are limited since a few specific decay products and the associated down-scatter overwhelm the gamma rays of interest. Active interrogation methods produce gamma rays beyond 3 MeV, minimizing the impact of the passive emissions that drop off sharply above this energy. New devices like the Ultra-High Rate Germanium (UHRGe) detector are being developed to advance these novel measurement methods. Designed for reasonable resolution at 106 s-1 output rates (compared to ~ 1 - 10 e 3 s-1 standards), SNF samples were directly measured using UHRGe and compared to models. Model verification further enables using Los Alamos National Laboratory SNF assembly models, developed under the Next Generation Safeguards Initiative, to determine emission and signal expectations. Measurement results and future application requirements for UHRGe will be discussed.

  4. Measurements of neutron distribution in neutrons-gamma-rays mixed field using imaging plate for neutron capture therapy.

    PubMed

    Tanaka, Kenichi; Endo, Satoru; Hoshi, Masaharu

    2010-01-01

    The imaging plate (IP) technique is tried to be used as a handy method to measure the spatial neutron distribution via the (157)Gd(n,gamma)(158)Gd reaction for neutron capture therapy (NCT). For this purpose, IP is set in a water phantom and irradiated in a mixed field of neutrons and gamma-rays. The Hiroshima University Radiobiological Research Accelerator is utilized for this experiment. The neutrons are moderated with 20-cm-thick D(2)O to obtain suitable neutron field for NCT. The signal for IP doped with Gd as a neutron-response enhancer is subtracted with its contribution by gamma-rays, which was estimated using IP without Gd. The gamma-ray response of Gd-doped IP to non-Gd IP is set at 1.34, the value measured for (60)Co gamma-rays, in estimating the gamma-ray contribution to Gd-doped IP signal. Then measured distribution of the (157)Gd(n,gamma)(158)Gd reaction rate agrees within 10% with the calculated value based on the method that has already been validated for its reproducibility of Au activation. However, the evaluated distribution of the (157)Gd(n,gamma)(158)Gd reaction rate is so sensitive to gamma-ray energy, e.g. the discrepancy of the (157)Gd(n,gamma)(158)Gd reaction rate between measurement and calculation becomes 30% for the photon energy change from 33keV to 1.253MeV.

  5. Statistical measurement of the gamma-ray source-count distribution as a function of energy

    NASA Astrophysics Data System (ADS)

    Zechlin, H.-S.; Cuoco, A.; Donato, F.; Fornengo, N.; Regis, M.

    2017-01-01

    Photon counts statistics have recently been proven to provide a sensitive observable for characterizing gamma-ray source populations and for measuring the composition of the gamma-ray sky. In this work, we generalize the use of the standard 1-point probability distribution function (1pPDF) to decompose the high-latitude gamma-ray emission observed with Fermi-LAT into: (i) point-source contributions, (ii) the Galactic foreground contribution, and (iii) a diffuse isotropic background contribution. We analyze gamma-ray data in five adjacent energy bands between 1 and 171 GeV. We measure the source-count distribution dN/dS as a function of energy, and demonstrate that our results extend current measurements from source catalogs to the regime of so far undetected sources. Our method improves the sensitivity for resolving point-source populations by about one order of magnitude in flux. The dN/dS distribution as a function of flux is found to be compatible with a broken power law. We derive upper limits on further possible breaks as well as the angular power of unresolved sources. We discuss the composition of the gamma-ray sky and capabilities of the 1pPDF method.

  6. (p,$gamma$) ANGULAR DISTRIBUTION MEASUREMENTS ON F$sup 19$(p,$alpha$$gamma$)O$sup 16$ AT 340, 598, AND 669 kev (in German)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Retz-Schmidt, Th.

    1958-10-01

    Experimental envestigations of the behavior of the 6.14-Mev radiation in the F/sup 19/(p, alpha gamma )O/sup 16/ reaction gave the following angular distributions: I gamma (669) ~ isotrop, I gamma (598) ~ 1 + 0.17 cos/sup 2/ THETA , and I gamma (340) ~ 1-0.035 cos/sup 2/ THETA . The result in the last case which deviates from earlier measurements is in better agreement with the basic assumption that in addition to the s-protons approximately 1% d-protons participate in the reaction at E/sub p/ = 340 kev. (tr-auth)

  7. Gamma Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    2000-01-01

    The project has progressed successfully during this period of performance. The highlights of the Gamma Ray Astronomy teams efforts are: (1) Support daily BATSE data operations, including receipt, archival and dissemination of data, quick-look science analysis, rapid gamma-ray burst and transient monitoring and response efforts, instrument state-of-health monitoring, and instrument commanding and configuration; (2) On-going scientific analysis, including production and maintenance of gamma-ray burst, pulsed source and occultation source catalogs, gamma-ray burst spectroscopy, studies of the properties of pulsars and black holes, and long-term monitoring of hard x-ray sources; (3) Maintenance and continuous improvement of BATSE instrument response and calibration data bases; (4) Investigation of the use of solid state detectors for eventual application and instrument to perform all sky monitoring of X-Ray and Gamma sources with high sensitivity; and (5) Support of BATSE outreach activities, including seminars, colloquia and World Wide Web pages. The highlights of this efforts can be summarized in the publications and presentation list.

  8. Gamma-Ray Dose Measurement with Radio-Photoluminescence Glass Dosimeter in Mixed Radiation Field for BNCT

    NASA Astrophysics Data System (ADS)

    Hiramatsu, K.; Yoshihashi, S.; Kusaka, S.; Sato, F.; Hoashi, E.; Murata, I.

    2017-09-01

    Accelerator based neutron sources (ABNS) are being developed as the next generation neutron irradiation system for BNCT. From the ABNS, unnecessary gamma-rays will be generated by neutron capture reactions, as well as fast neutrons. To control the whole-body radiation dose to the patient, measurement of gamma-ray dose in the irradiation room is necessary. In this study, the objective is to establish a method to measure gamma-ray dose separately in a neutron/gamma mixed field by using RPL glass dosimeter. For this purpose, we proposed a lead filter method which uses a pair of RPL glasses with and without a lead filter outside. In order to realize this method, the basic characteristics of glass dosimeter was verified in the gamma-ray field, before adapting it in the mixture field. From the result of the experiment using the lead filter, the simulation result especially for the case with a lead filter overestimated the absorbed does obtained from measurement. We concluded that the reason of the discrepancy is caused by existence of gradient of the dose distribution in the glass, and the difference of sensitivity to low-energy photon between measurement and theory.

  9. Experimental setup for radon exposure and first diffusion studies using gamma spectroscopy

    NASA Astrophysics Data System (ADS)

    Maier, Andreas; van Beek, Patrick; Hellmund, Johannes; Durante, Marco; Schardt, Dieter; Kraft, Gerhard; Fournier, Claudia

    2015-11-01

    In order to measure the uptake and diffusion of 222Rn in biological material, an exposure chamber was constructed where cell cultures, biological tissues and mice can be exposed to 222Rn-activities similar to therapy conditions. After exposure, the material is transferred to a gamma spectrometer and the decay of 214Pb and 214Bi is analyzed. From the time kinetics of these decays the total amount of the initial 222Rn concentration can be calculated. In this paper the design and construction as well as first test measurements are reported.

  10. Gamma ray spectroscopy in astrophysics: Solar gamma ray astronomy on solar maximum mission. [experimental design

    NASA Technical Reports Server (NTRS)

    Forrest, D. J.

    1978-01-01

    The SMM gamma ray experiment and the important scientific capabilities of the instrument are discussed. The flare size detectable as a function of spectrum integration time was studied. A preliminary estimate indicates that a solar gamma ray line at 4.4 MeV one-fifth the intensity of that believed to have been emitted on 4 August 1972 can be detected in approximately 1000 sec with a confidence level of 99%.

  11. Neutron and gamma-ray energy reconstruction for characterization of special nuclear material

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Clarke, Shaun D.; Hamel, Michael C.; Di fulvio, Angela

    Characterization of special nuclear material may be performed using energy spectroscopy of either the neutron or gamma-ray emissions from the sample. Gamma-ray spectroscopy can be performed relatively easily using high-resolution semiconductors such as high-purity germanium. Neutron spectroscopy, by contrast, is a complex inverse problem. Here, results are presented for 252Cf and PuBe energy spectra unfolded using a single EJ309 organic scintillator; excellent agreement is observed with the reference spectra. Neutron energy spectroscopy is also possible using a two-plane detector array, whereby time-offlight kinematics can be used. With this system, energy spectra can also be obtained as a function of position.more » Finally, spatial-dependent energy spectra are presented for neutron and gamma-ray sources that are in excellent agreement with expectations.« less

  12. Neutron and gamma-ray energy reconstruction for characterization of special nuclear material

    DOE PAGES

    Clarke, Shaun D.; Hamel, Michael C.; Di fulvio, Angela; ...

    2017-06-30

    Characterization of special nuclear material may be performed using energy spectroscopy of either the neutron or gamma-ray emissions from the sample. Gamma-ray spectroscopy can be performed relatively easily using high-resolution semiconductors such as high-purity germanium. Neutron spectroscopy, by contrast, is a complex inverse problem. Here, results are presented for 252Cf and PuBe energy spectra unfolded using a single EJ309 organic scintillator; excellent agreement is observed with the reference spectra. Neutron energy spectroscopy is also possible using a two-plane detector array, whereby time-offlight kinematics can be used. With this system, energy spectra can also be obtained as a function of position.more » Finally, spatial-dependent energy spectra are presented for neutron and gamma-ray sources that are in excellent agreement with expectations.« less

  13. Cosmic-ray effects on diffuse gamma-ray measurements.

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.

    1972-01-01

    Evaluation of calculations and experimental evidence from 600-MeV proton irradiation indicating that cosmic-ray-induced radioactivity in detectors used to measure the diffuse gamma-ray background produces a significant counting rate in the energy region around 1 MeV. It is concluded that these counts may be responsible for the observed flattening of the diffuse photon spectrum at this energy.

  14. Gamma-ray imaging system for real-time measurements in nuclear waste characterisation

    NASA Astrophysics Data System (ADS)

    Caballero, L.; Albiol Colomer, F.; Corbi Bellot, A.; Domingo-Pardo, C.; Leganés Nieto, J. L.; Agramunt Ros, J.; Contreras, P.; Monserrate, M.; Olleros Rodríguez, P.; Pérez Magán, D. L.

    2018-03-01

    A compact, portable and large field-of-view gamma camera that is able to identify, locate and quantify gamma-ray emitting radioisotopes in real-time has been developed. The device delivers spectroscopic and imaging capabilities that enable its use it in a variety of nuclear waste characterisation scenarios, such as radioactivity monitoring in nuclear power plants and more specifically for the decommissioning of nuclear facilities. The technical development of this apparatus and some examples of its application in field measurements are reported in this article. The performance of the presented gamma-camera is also benchmarked against other conventional techniques.

  15. Aerosol and gamma background measurements at Basic Environmental Observatory Moussala

    NASA Astrophysics Data System (ADS)

    Angelov, Christo; Arsov, Todor; Penev, Ilia; Nikolova, Nina; Kalapov, Ivo; Georgiev, Stefan

    2016-03-01

    Trans boundary and local pollution, global climate changes and cosmic rays are the main areas of research performed at the regional Global Atmospheric Watch (GAW) station Moussala BEO (2925 m a.s.l., 42°10'45'' N, 23°35'07'' E). Real time measurements and observations are performed in the field of atmospheric chemistry and physics. Complex information about the aerosol is obtained by using a threewavelength integrating Nephelometer for measuring the scattering and backscattering coefficients, a continuous light absorption photometer and a scanning mobile particle sizer. The system for measuring radioactivity and heavy metals in aerosols allows us to monitor a large scale radioactive aerosol transport. The measurements of the gamma background and the gamma-rays spectrum in the air near Moussala peak are carried out in real time. The HYSPLIT back trajectory model is used to determine the origin of the data registered. DREAM code calculations [2] are used to forecast the air mass trajectory. The information obtained combined with a full set of corresponding meteorological parameters is transmitted via a high frequency radio telecommunication system to the Internet.

  16. Gamma-ray burst spectroscopy capabilities of the BATSE/GRO experiment

    NASA Technical Reports Server (NTRS)

    Matteson, J. L.; Fishman, G. J.; Meegan, C. A.; Parnell, T. A.; Wilson, R. B.; Paciesas, W.; Cline, T. L.; Teegarden, B. J.

    1985-01-01

    A scintillation spectrometer is included in each of the eight BATSE/GRO detector modules, resulting in all-sky coverage for gamma-ray bursts. The scientific motivation, design and capabilities of these spectrometers for performing spectral observations over a wide range of gamma-ray energies and burst intensities are described.

  17. Measurement of U-235 Fission Neutron Spectra Using a Multiple Gamma Coincidence Technique

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ji Chuncheng; Kegel, G.H.R.; Egan, J.J.

    2005-05-24

    The Los Alamos Model of Madland and Nix predicts the shape of the fission neutron energy spectrum for incident primary neutrons of different energies. Verifications of the model normally are limited to measurements of the fission neutron spectra for energies higher than that of the primary neutrons because the low-energy spectrum is distorted by the admixture of elastically and inelastically scattered neutrons. This situation can be remedied by using a measuring technique that separates fission from scattering events. One solution consists of using a fissile sample so thin that fission fragments can be observed indicating the occurrence of a fissionmore » event. A different approach is considered in this paper. It has been established that a fission event is accompanied by the emission of between seven and eight gamma rays, while in a scattering interaction, between zero and two gammas are emitted, so that a gamma multiplicity detector should supply a datum to distinguish a fission event from a scattering event. We proceed as follows: A subnanosecond pulsed and bunched proton beam from the UML Van de Graaff generates nearly mono-energetic neutrons by irradiating a thin metallic lithium target. The neutrons irradiate a 235U sample. Emerging neutron energies are measured with a time-of-flight spectrometer. A set of four BaF2 detectors is located close to the 235U sample. These detectors together with their electronic components identify five different events for each neutron detected, i.e., whether four, three, two, one, or none of the BaF2 detectors received one (or more) gamma rays. We present work, preliminary to the final measurements, involving feasibility considerations based on gamma-ray coincidence measurements with four BaF2 detectors, and the design of a Fission-Scattering Discriminator under construction.« less

  18. Infrared Spectroscopy of Explosives Residues: Measurement Techniques and Spectral Analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Phillips, Mark C.; Bernacki, Bruce E.

    2015-03-11

    Infrared laser spectroscopy of explosives is a promising technique for standoff and non-contact detection applications. However, the interpretation of spectra obtained in typical standoff measurement configurations presents numerous challenges. Understanding the variability in observed spectra from explosives residues and particles is crucial for design and implementation of detection algorithms with high detection confidence and low false alarm probability. We discuss a series of infrared spectroscopic techniques applied toward measuring and interpreting the reflectance spectra obtained from explosives particles and residues. These techniques utilize the high spectral radiance, broad tuning range, rapid wavelength tuning, high scan reproducibility, and low noise ofmore » an external cavity quantum cascade laser (ECQCL) system developed at Pacific Northwest National Laboratory. The ECQCL source permits measurements in configurations which would be either impractical or overly time-consuming with broadband, incoherent infrared sources, and enables a combination of rapid measurement speed and high detection sensitivity. The spectroscopic methods employed include standoff hyperspectral reflectance imaging, quantitative measurements of diffuse reflectance spectra, reflection-absorption infrared spectroscopy, microscopic imaging and spectroscopy, and nano-scale imaging and spectroscopy. Measurements of explosives particles and residues reveal important factors affecting observed reflectance spectra, including measurement geometry, substrate on which the explosives are deposited, and morphological effects such as particle shape, size, orientation, and crystal structure.« less

  19. The Z {yields} cc-bar {yields} {gamma}{gamma}*, Z {yields} bb-bar {yields} {gamma}{gamma}* triangle diagrams and the Z {yields} {gamma}{psi}, Z {yields} {gamma}Y decays

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Achasov, N. N., E-mail: achasov@math.nsc.ru

    2011-03-15

    The approach to the Z {yields} {gamma}{psi} and Z {yields} {gamma}Y decay study is presented in detail, based on the sum rules for the Z {yields} cc-bar {yields} {gamma}{gamma}* and Z {yields} bb-bar {yields} {gamma}{gamma}* amplitudes and their derivatives. The branching ratios of the Z {yields} {gamma}{psi} and Z {yields} {gamma}Y decays are calculated for different hypotheses on saturation of the sum rules. The lower bounds of {Sigma}{sub {psi}} BR(Z {yields} {gamma}{psi}) = 1.95 Multiplication-Sign 10{sup -7} and {Sigma}{sub {upsilon}} BR(Z {yields} {gamma}Y) = 7.23 Multiplication-Sign 10{sup -7} are found. Deviations from the lower bounds are discussed, including the possibilitymore » of BR(Z {yields} {gamma}J/{psi}(1S)) {approx} BR(Z {yields} {gamma}Y(1S)) {approx} 10{sup -6}, that could be probably measured in LHC. The angular distributions in the Z {yields} {gamma}{psi} and Z {yields} {gamma}Y decays are also calculated.« less

  20. Determination of the measurement threshold in gamma-ray spectrometry.

    PubMed

    Korun, M; Vodenik, B; Zorko, B

    2017-03-01

    In gamma-ray spectrometry the measurement threshold describes the lover boundary of the interval of peak areas originating in the response of the spectrometer to gamma-rays from the sample measured. In this sense it presents a generalization of the net indication corresponding to the decision threshold, which is the measurement threshold at the quantity value zero for a predetermined probability for making errors of the first kind. Measurement thresholds were determined for peaks appearing in the spectra of radon daughters 214 Pb and 214 Bi by measuring the spectrum 35 times under repeatable conditions. For the calculation of the measurement threshold the probability for detection of the peaks and the mean relative uncertainty of the peak area were used. The relative measurement thresholds, the ratios between the measurement threshold and the mean peak area uncertainty, were determined for 54 peaks where the probability for detection varied between some percent and about 95% and the relative peak area uncertainty between 30% and 80%. The relative measurement thresholds vary considerably from peak to peak, although the nominal value of the sensitivity parameter defining the sensitivity for locating peaks was equal for all peaks. At the value of the sensitivity parameter used, the peak analysis does not locate peaks corresponding to the decision threshold with the probability in excess of 50%. This implies that peaks in the spectrum may not be located, although the true value of the measurand exceeds the decision threshold. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Prospects for Dark Matter Measurements with the Advanced Gamma Ray Imaging System (AGIS)

    NASA Astrophysics Data System (ADS)

    Buckley, James

    2009-05-01

    AGIS, a concept for a future gamma-ray observatory consisting of an array of 50 atmospheric Cherenkov telescopes, would provide a powerful new tool for determining the nature of dark matter and its role in structure formation in the universe. The advent of more sensitive direct detection experiments, the launch of Fermi and the startup of the LHC make the near future an exciting time for dark matter searches. Indirect measurements of cosmic-ray electrons may already provide a hint of dark matter in our local halo. However, gamma-ray measurements will provide the only means for mapping the dark matter in the halo of our galaxy and other galaxies. In addition, the spectrum of gamma-rays (either direct annihilation to lines or continuum emission from other annihilation channels) will be imprinted with the mass of the dark matter particle, and the particular annihilation channels providing key measurements needed to identify the dark matter particle. While current gamma-ray instruments fall short of the generic sensitivity required to measure the dark matter signal from any sources other than the (confused) region around the Galactic center, we show that the planned AGIS array will have the angular resolution, energy resolution, low threshold energy and large effective area required to detect emission from dark matter annihilation in Galactic substructure or nearby Dwarf spheroidal galaxies.

  2. Application of gamma imaging techniques for the characterisation of position sensitive gamma detectors

    NASA Astrophysics Data System (ADS)

    Habermann, T.; Didierjean, F.; Duchêne, G.; Filliger, M.; Gerl, J.; Kojouharov, I.; Li, G.; Pietralla, N.; Schaffner, H.; Sigward, M.-H.

    2017-11-01

    A device to characterize position-sensitive germanium detectors has been implemented at GSI. The main component of this so called scanning table is a gamma camera that is capable of producing online 2D images of the scanned detector by means of a PET technique. To calibrate the gamma camera Compton imaging is employed. The 2D data can be processed further offline to obtain depth information. Of main interest is the response of the scanned detector in terms of the digitized pulse shapes from the preamplifier. This is an important input for pulse-shape analysis algorithms as they are in use for gamma tracking arrays in gamma spectroscopy. To validate the scanning table, a comparison of its results with a second scanning table implemented at the IPHC Strasbourg is envisaged. For this purpose a pixelated germanium detector has been scanned.

  3. High resolution X- and gamma-ray spectroscopy of cosmic X-ray sources

    NASA Technical Reports Server (NTRS)

    Lin, R. P.

    1983-01-01

    A high resolution X-ray spectrometer and large area phoswich detector were designed and co-aligned in a common elevation mounting in order to measure solar and cosmic X-ray and gamma ray emission in the 13 to 600 KeV energy range from a balloon. The instrument is described and results obtained for the Crab Nebula, the supernova remnant Cas A, and the Sun are discussed and analyzed.

  4. Study of the Nuclear Structure of 39P Using Beta-Delayed Gamma Spectroscopy

    NASA Astrophysics Data System (ADS)

    Abromeit, Brittany; NSCL Experiment E14063 Team Team

    2016-03-01

    Investigation of nuclei with neutron and proton imbalance is at the forefront of nuclear physics research today. This is driven by the fact that the structure in these regimes may vary with that seen near the valley of stability. With eight neutrons more than the stable isotope of phosphorous, 39P is a neutron-rich exotic nucleus that has very limited information on it: previous studies of 39P produce only three known energy levels and gamma rays. The fragmentation of a 48Ca primary beam on a 564mg/cm2 thick Be target at the National Superconducting Cyclotron Laboratory (NSCL) was used to produce exotic 39Si. Using the NSCL Beta Counting System (BCS), consisting of a thick planner germanium double-sided strip detector (GeDSSD) and 16 High-purity germanium detectors in an array, SeGA, the beta-gamma coincidences from the decay of 39Si to 39P were analyzed. The resulting level scheme of 39P, including over 12 new gamma rays and energy states, confirmation of the previously measured half-life, and first-time logft values will be presented. This work was supported by the NSF under Grant No. 1401574.

  5. Airborne gamma radiation soil moisture measurements over short flight lines

    NASA Technical Reports Server (NTRS)

    Peck, Eugene L.; Carrol, Thomas R.; Lipinski, Daniel M.

    1990-01-01

    Results are presented on airborne gamma radiation measurements of soil moisture condition, carried out along short flight lines as part of the First International Satellite Land Surface Climatology Project Field Experiment (FIFE). Data were collected over an area in Kansas during the summers of 1987 and 1989. The airborne surveys, together with ground measurements, provide the most comprehensive set of airborne and ground truth data available in the U.S. for calibrating and evaluating airborne gamma flight lines. Analysis showed that, using standard National Weather Service weights for the K, Tl, and Gc radiation windows, the airborne soil moisture estimates for the FIFE lines had a root mean square error of no greater than 3.0 percent soil moisture. The soil moisture estimates for sections having acquisition time of at least 15 sec were found to be reliable.

  6. 241Am (n,gamma) isomer ratio measurement

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bond, Evelyn M; Vieira, David J; Moody, Walter A

    The objective of this project is to improve the accuracy of the {sup 242}Cm/{sup 241}Am radiochemistry ratio. We have performed an activation experiment to measure the {sup 241}Am(n,{gamma}) cross section leading to either the ground state of {sup 242g}Am (t{sub 1/2} = 16 hr) which decays to {sup 242}Cm (t{sub 1/2} = 163 d) or the long-lived isomer {sup 242m}Am (t{sub 1/2} = 141 yr). This experiment will develop a new set of americium cross section evaluations that can be used with a measured {sup 242}Cm/{sup 241}Am radiochemical measurement for nuclear forensic purposes. This measurement is necessary to interpret themore » {sup 242}Cm/{sup 241}Am ratio because a good measurement of this neutron capture isomer ratio for {sup 241}Am does not exist. The targets were prepared in 2007 from {sup 241}Am purified from LANL stocks. Gold was added to the purified {sup 241}Am as an internal neutron fluence monitor. These targets were placed into a holder, packaged, and shipped to Forschungszentrum Karlsruhe, where they were irradiated at their Van de Graff facility in February 2008. One target was irradiated with {approx}25 keV quasimonoenergetic neutrons produced by the {sup 7}Li(p,n) reaction for 3 days and a second target was also irradiated for 3 days with {approx}500 keV neutrons. Because it will be necessary to separate the {sup 242}Cm from the {sup 241}Am in order to measure the amount of {sup 242}Cm by alpha spectrometry, research into methods for americium/curium separations were conducted concurrently. We found that anion exchange chromatography in methanol/nitric acid solutions produced good separations that could be completed in one day resulting in a sample with no residue. The samples were returned from Germany in July 2009 and were counted by gamma spectrometry. Chemical separations have commenced on the blank sample. Each sample will be spiked with {sup 244}Cm, dissolved and digested in nitric acid solutions. One third of each sample will be processed at a

  7. The gamma irradiation effects on structural and optical properties of silk fibroin/HPMC blend films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shetty, G. Rajesha; Rao, B. Lakshmeesha; Gowda, Mahadeva

    In this paper the structural, chemical and optical properties of gamma irradiated silk fibroin/Hydroxypropyl methyl cellulose (SF-HPMC) blend films were studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-visible spectroscopy. The results indicate that the gamma radiation did not affect significantly the primary structure of polypeptide arrangement in the blend films. But the optical properties of the blends changed with gamma irradiation dosage.

  8. Gamma-ray spectroscopy of 131Sn81 via the (9Be, 8Be γ) reaction

    NASA Astrophysics Data System (ADS)

    Burcher, Sean; Bey, A.; Jones, K.; Ahn, S. H.; Ayres, A.; Schmitt, K. T.; Allmond, J.; Galindo-Urribari, A.; Radford, D. C.; Liang, J. F.; Neseraja, C. D.; Pain, S. D.; Pittman, S. T.; Smith, M. S.; Stracener, D. W.; Varner, R. L.; Bardayan, D. W.; O'Malley, P. D.; Cizewski, J. A.; Howard, M. E.; Manning, B. M.; Garcia Ruiz, R. F.; Kozub, R. L.; Matos, M.; Padilla-Rodal, E.

    2016-09-01

    Nuclear data in the region of the doubly-magic nucleus 132Sn82 is useful for benchmarking nuclear structure theories due to the clean single-particle nature of the nuclear wavefunction near the closed shells. At the Holifield Radioactive Ion Beam Facility (HRIBF) neutron-rich beams in the 132Sn82 region were produced via proton-induced fission of a Uranium-Carbide target. The CLARION array of HPGe detectors was coupled with the HyBall array of CsI detectors to allow for particle-gamma coincidence measurements. The gamma-ray de-excitation of the four lowest lying single-neutron states has been observed for the first time via the (9Be,8Be γ) reaction. The excitation energy of these states have been measured to higher precision than was possible with the previous charged particle measurement. This work was supported in part by the U.S. Department of Energy and the National Science Foundation.

  9. Anisotropies in the Diffuse Gamma-Ray Background Measured by the Fermi LAT

    NASA Technical Reports Server (NTRS)

    Ferrara, E. C.; McEnery, J. E.; Troja, E.

    2012-01-01

    The contribution of unresolved sources to the diffuse gamma-ray background could induce anisotropies in this emission on small angular scales. We analyze the angular power spectrum of the diffuse emission measured by the Fermi LAT at Galactic latitudes absolute value of b > 30 deg in four energy bins spanning 1 to 50 GeV. At multipoles l >= 155, corresponding to angular scales approx < 2 deg, angular power above the photon noise level is detected at > 99.99% CL in the 1-2 GeV, 2- 5 GeV, and 5- 10 GeV energy bins, and at > 99% CL at 10-50 GeV. Within each energy bin the measured angular power takes approximately the same value at all multipoles l >= 155, suggesting that it originates from the contribution of one or more unclustered source populations. The amplitude of the angular power normalized to the mean intensity in each energy bin is consistent with a constant value at all energies, C(sub p) / (I)(exp 2) = 9.05 +/- 0.84 x 10(exp -6) sr, while the energy dependence of C(sub p) is consistent with the anisotropy arising from one or more source populations with power-law photon spectra with spectral index Gamma (sub s) = 2.40 +/- 0.07. We discuss the implications of the measured angular power for gamma-ray source populations that may provide a contribution to the diffuse gamma-ray background.

  10. Si Lattice, Avogadro Constant, and X- and Gamma-Ray Measurements: Contributions by R.D. Deslattes

    NASA Astrophysics Data System (ADS)

    Kessler, Jr.

    2002-04-01

    The achievement of x-ray interferometry in 1965 opened the possibility of more accurately measuring the lattice spacing of a diffraction crystal on a scale directly tied to the SI system of units. The road from the possible to reality required moving objects and measuring translations with sub-atomic accuracy. The improved crystal lattice spacing determinations had a significant impact on two fundamental measurement areas: 1) the amount of substance (the mole and the associated Avogadro Constant), and 2) short wavelengths (the x- and gamma-ray regions). Progress in both areas required additional metrological advances: density and isotopic abundance measurements are needed for the Avogadro constant and small angle measurements are required for the determination of short wavelengths. The x- and gamma-ray measurements have led to more accurate wavelength standards and neutron binding energy measurements that connect gamma-ray measurements to precision atomic mass measurements, particularly the neutron mass. Richard D. Deslattes devoted much of his scientific career to this measurement program. His outstanding contributions and insights will be reviewed.

  11. Measurement of the {sup 12}C({alpha},{gamma}){sup 16}O reaction at TRIAC

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Makii, H.; Miyatake, H.; Wakabayashi, Y.

    2012-11-12

    We have measured the {gamma}-ray angular distribution of the {sup 12}C({alpha},{gamma}){sup 16}O reaction at TRIAC (Tokai Radioactive Ion Accelerator Complex) to accurately determine the E1 and E2 cross sections. In this experiment, we used high efficiency anti-Compton NaI(T1) spectrometers to detect a {gamma}-ray from the reaction with large S/N ratio, intense pulsed {alpha}-beams to discriminate true event from background events due to neutrons from {sup 13}C({alpha},n){sup 16}O reaction with a time-of-flight (TOF) method. We succeeded in removing a background events due to neutrons and clearly detected {gamma}-ray from the {sup 12}C({alpha}{gamma}){sup 16}O reaction with high statistics.

  12. Measured neutron and gamma spectra from californium-252 in a tissue-equivalent medium.

    PubMed

    Elson, H R; Stupar, T A; Shapiro, A; Kereiakes, J G

    1979-01-01

    A method of experimentally obtaining both neutron and gamma-ray spectra in a scattering medium is described. The method utilizes a liquid-organic scintillator (NE-213) coupled with a pulse-shape discrimination circuit. This allows the separation of the neutron-induced pulse-height data from the gamma-ray pulse-height data. Using mathematical unfolding techniques, the two sets of pulse-height data were transformed to obtain the neutron and gamma-ray energy spectra. A small spherical detector was designed and constructed to reduce the errors incurred by attempting spectral measurements in a scattering medium. Demonstration of the utility of the system to obtain the neutron and gamma-ray spectra in a scattering medium was performed by characterizing the neutron and gamma-ray spectra at various sites about a 3.7-microgram (1.5 cm active length) californium-252 source in a tissue-equivalent medium.

  13. Coherent Raman spectroscopies for measuring molecular flow velocity

    NASA Technical Reports Server (NTRS)

    She, C. Y.

    1982-01-01

    Various types of coherent Raman spectroscopy are characterized and their application to molecular flow velocity and direction measurement and species concentration and temperature determination is discussed.

  14. Radiation detection system for portable gamma-ray spectroscopy

    DOEpatents

    Rowland, Mark S [Alamo, CA; Howard, Douglas E [Livermore, CA; Wong, James L [Dublin, CA; Jessup, James L [Tracy, CA; Bianchini, Greg M [Livermore, CA; Miller, Wayne O [Livermore, CA

    2006-06-20

    A portable gamma ray detection apparatus having a gamma ray detector encapsulated by a compact isolation structure having at least two volumetrically-nested enclosures where at least one is a thermal shield. The enclosures are suspension-mounted to each other to successively encapsulate the detector without structural penetrations through the thermal shields. A low power cooler is also provided capable of cooling the detector to cryogenic temperatures without consuming cryogens, due to the heat load reduction by the isolation structure and the reduction in the power requirements of the cooler. The apparatus also includes a lightweight portable power source for supplying power to the apparatus, including to the cooler and the processing means, and reducing the weight of the apparatus to enable handheld operation or toting on a user's person.

  15. The Probing In-Situ With Neutron and Gamma Rays (PING) Instrument for Planetary Composition Measurements

    NASA Technical Reports Server (NTRS)

    Parsons, A.; Bodnarik, J.; Evans, L.; McClanahan, T.; Namkung, M.; Nowicki, S.; Schweitzer, J.; Starr, R.

    2012-01-01

    The Probing In situ with Neutrons and Gamma rays (PING) instrument (formerly named PNG-GRAND) [I] experiment is an innovative application of the active neutron-gamma ray technology successfully used in oil field well logging and mineral exploration on Earth over many decades. The objective of our active neutron-gamma ray technology program at NASA Goddard Space Flight Center (NASA/GSFC) is to bring PING to the point where it can be flown on a variety of surface lander or rover missions to the Moon, Mars, Venus, asteroids, comets and the satellites of the outer planets and measure their bulk surface and subsurface elemental composition without the need to drill into the surface. Gamma-Ray Spectrometers (GRS) have been incorporated into numerous orbital planetary science missions. While orbital measurements can map a planet, they have low spatial and elemental sensitivity due to the low surface gamma ray emission rates reSUlting from using cosmic rays as an excitation source, PING overcomes this limitation in situ by incorporating a powerful neutron excitation source that permits significantly higher elemental sensitivity elemental composition measurements. PING combines a 14 MeV deuterium-tritium Pulsed Neutron Generator (PNG) with a gamma ray spectrometer and two neutron detectors to produce a landed instrument that can determine the elemental composition of a planet down to 30 - 50 cm below the planet's surface, The penetrating nature of .5 - 10 MeV gamma rays and 14 MeV neutrons allows such sub-surface composition measurements to be made without the need to drill into or otherwise disturb the planetary surface, thus greatly simplifying the lander design, We are cun'ently testing a PING prototype at a unique outdoor neutron instrumentation test facility at NASA/GSFC that provides two large (1.8 m x 1.8 m x ,9 m) granite and basalt test formations placed outdoors in an empty field, Since an independent trace elemental analysis has been performed on both these

  16. Diode laser spectroscopy: precise spectral line shape measurements

    NASA Astrophysics Data System (ADS)

    Nadezhdinskii, A. I.

    1996-07-01

    When one speaks about modern trends in tunable diode laser spectroscopy (TDLS) one should mention that precise line shape measurements have become one of the most promising applications of diode lasers in high resolution molecular spectroscopy. Accuracy limitations of TDL spectrometers are considered in this paper, proving the ability to measure spectral line profile with precision better than 1%. A four parameter Voigt profile is used to fit the experimental spectrum, and the possibility of line shift measurements with an accuracy of 2 × 10 -5 cm -1 is shown. Test experiments demonstrate the error line intensity ratios to be less than 0.3% for the proposed approach. Differences between "soft" and "hard" models of line shape have been observed experimentally for the first time. Some observed resonance effects are considered with respect to collision adiabacity.

  17. Precision Gamma-Ray Branching Ratios for Long-Lived Radioactive Nuclei

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tonchev, Anton

    Many properties of the high-energy-density environments in nuclear weapons tests, advanced laser-fusion experiments, the interior of stars, and other astrophysical bodies must be inferred from the resulting long-lived radioactive nuclei that are produced. These radioactive nuclei are most easily and sensitively identified by studying the characteristic gamma rays emitted during decay. Measuring a number of decays via detection of the characteristic gamma-rays emitted during the gamma-decay (the gamma-ray branching ratio) of the long-lived fission products is one of the most straightforward and reliable ways to determine the number of fissions that occurred in a nuclear weapon test. The fission productsmore » 147Nd, 144Ce, 156Eu, and certain other long-lived isotopes play a crucial role in science-based stockpile stewardship, however, the large uncertainties (about 8%) on the branching ratios measured for these isotopes are currently limiting the usefulness of the existing data [1,2]. We performed highly accurate gamma-ray branching-ratio measurements for a group of high-atomic-number rare earth isotopes to greatly improve the precision and reliability with which the fission yield and reaction products in high-energy-density environments can be determined. We have developed techniques that take advantage of new radioactive-beam facilities, such as DOE's CARIBU located at Argonne National Laboratory, to produce radioactive samples and perform decay spectroscopy measurements. The absolute gamma-ray branching ratios for 147Nd and 144Ce are reduced <2% precision. In addition, high-energy monoenergetic neutron beams from the FN Tandem accelerator in TUNL at Duke University was used to produce 167Tm using the 169Tm(n,3n) reaction. Fourtime improved branching ratio of 167Tm is used now to measure reaction-in-flight (RIF) neutrons from a burning DT capsule at NIF [10]. This represents the first measurement of RIF neutrons in any laboratory fusion system, and the magnitude

  18. Technical Note: PRESAGE three-dimensional dosimetry accurately measures Gamma Knife output factors

    PubMed Central

    Klawikowski, Slade J.; Yang, James N.; Adamovics, John; Ibbott, Geoffrey S.

    2014-01-01

    Small-field output factor measurements are traditionally very difficult because of steep dose gradients, loss of lateral electronic equilibrium, and dose volume averaging in finitely sized detectors. Three-dimensional (3D) dosimetry is ideal for measuring small output factors and avoids many of these potential challenges of point and two-dimensional detectors. PRESAGE 3D polymer dosimeters were used to measure the output factors for the 4 mm and 8 mm collimators of the Leksell Perfexion Gamma Knife radiosurgery treatment system. Discrepancies between the planned and measured distance between shot centers were also investigated. A Gamma Knife head frame was mounted onto an anthropomorphic head phantom. Special inserts were machined to hold 60 mm diameter, 70 mm tall cylindrical PRESAGE dosimeters. The phantom was irradiated with one 16 mm shot and either one 4 mm or one 8 mm shot, to a prescribed dose of either 3 Gy or 4 Gy to the 50% isodose line. The two shots were spaced between 30 mm and 60 mm apart and aligned along the central axis of the cylinder. The Presage dosimeters were measured using the DMOS-RPC optical CT scanning system. Five independent 4 mm output factor measurements fell within 2% of the manufacturer’s Monte Carlo simulation-derived nominal value, as did two independent 8 mm output factor measurements. The measured distances between shot centers varied by ± 0.8 mm with respect to the planned shot displacements. On the basis of these results, we conclude that PRESAGE dosimetry is excellently suited to quantify the difficult-to-measure Gamma Knife output factors. PMID:25368961

  19. Optical study of gamma irradiated sodium metaphosphate glasses containing divalent metal oxide MO (ZnO or CdO)

    NASA Astrophysics Data System (ADS)

    Nabhan, E.; Abd-Allah, W. M.; Ezz-El-Din, F. M.

    Sodium metaphosphate glasses containing divalent metal oxide, ZnO or CdO with composition 50 P2O5 - (50 - x) Na2O - x MO (ZnO, or CdO) where x = 0, 10, 20 (mol%) were prepared by conventional melt method. UV/visible spectroscopy and FTIR spectroscopy are measured before and after exposing to successive gamma irradiation doses (5-80 kGy). The optical absorption spectra results of the samples before irradiation reveal a strong UV absorption band at (∼230 nm) which is related to unavoided iron impurities. The effects of gamma irradiation on the optical spectral properties of the various glasses have been compared. From the optical absorption spectral data, the optical band gap is evaluated. The main structural groups and the influence of both divalent metal oxide and gamma irradiation effect on the structural vibrational groups are realized through IR spectroscopy. The FTIR spectra of γ-irradiated samples are characterized by the stability of the number and position for the main characteristic band of phosphate groups. To better understood the structural changes during γ-irradiation, a deconvolution of FTIR spectra in the range 650-1450 cm-1 is made. The FTIR deconvolution results found evidence that, the changes occurring after gamma irradiation have been related to irradiation induced structural defects and compositional changes.

  20. High-resolution gamma ray attenuation density measurements on mining exploration drill cores, including cut cores

    NASA Astrophysics Data System (ADS)

    Ross, P.-S.; Bourke, A.

    2017-01-01

    Physical property measurements are increasingly important in mining exploration. For density determinations on rocks, one method applicable on exploration drill cores relies on gamma ray attenuation. This non-destructive method is ideal because each measurement takes only 10 s, making it suitable for high-resolution logging. However calibration has been problematic. In this paper we present new empirical, site-specific correction equations for whole NQ and BQ cores. The corrections force back the gamma densities to the "true" values established by the immersion method. For the NQ core caliber, the density range extends to high values (massive pyrite, 5 g/cm3) and the correction is thought to be very robust. We also present additional empirical correction factors for cut cores which take into account the missing material. These "cut core correction factors", which are not site-specific, were established by making gamma density measurements on truncated aluminum cylinders of various residual thicknesses. Finally we show two examples of application for the Abitibi Greenstone Belt in Canada. The gamma ray attenuation measurement system is part of a multi-sensor core logger which also determines magnetic susceptibility, geochemistry and mineralogy on rock cores, and performs line-scan imaging.

  1. Assessment of Gamma-Ray-Spectra Analysis Method Utilizing the Fireworks Algorithm for Various Error Measures

    DOE PAGES

    Alamaniotis, Miltiadis; Tsoukalas, Lefteri H.

    2018-01-01

    The analysis of measured data plays a significant role in enhancing nuclear nonproliferation mainly by inferring the presence of patterns associated with special nuclear materials. Among various types of measurements, gamma-ray spectra is the widest utilized type of data in nonproliferation applications. In this paper, a method that employs the fireworks algorithm (FWA) for analyzing gamma-ray spectra aiming at detecting gamma signatures is presented. In particular, FWA is utilized to fit a set of known signatures to a measured spectrum by optimizing an objective function, where non-zero coefficients express the detected signatures. FWA is tested on a set of experimentallymore » obtained measurements optimizing various objective functions—MSE, RMSE, Theil-2, MAE, MAPE, MAP—with results exhibiting its potential in providing highly accurate and precise signature detection. Finally and furthermore, FWA is benchmarked against genetic algorithms and multiple linear regression, showing its superiority over those algorithms regarding precision with respect to MAE, MAPE, and MAP measures.« less

  2. Measurements of Soil Carbon by Neutron-Gamma Analysis in Static and Scanning Modes.

    PubMed

    Yakubova, Galina; Kavetskiy, Aleksandr; Prior, Stephen A; Torbert, H Allen

    2017-08-24

    The herein described application of the inelastic neutron scattering (INS) method for soil carbon analysis is based on the registration and analysis of gamma rays created when neutrons interact with soil elements. The main parts of the INS system are a pulsed neutron generator, NaI(Tl) gamma detectors, split electronics to separate gamma spectra due to INS and thermo-neutron capture (TNC) processes, and software for gamma spectra acquisition and data processing. This method has several advantages over other methods in that it is a non-destructive in situ method that measures the average carbon content in large soil volumes, is negligibly impacted by local sharp changes in soil carbon, and can be used in stationary or scanning modes. The result of the INS method is the carbon content from a site with a footprint of ~2.5 - 3 m 2 in the stationary regime, or the average carbon content of the traversed area in the scanning regime. The measurement range of the current INS system is >1.5 carbon weight % (standard deviation ± 0.3 w%) in the upper 10 cm soil layer for a 1 hmeasurement.

  3. Real-Time Airborne Gamma-Ray Background Estimation Using NASVD with MLE and Radiation Transport for Calibration

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kulisek, Jonathan A.; Schweppe, John E.; Stave, Sean C.

    2015-06-01

    Helicopter-mounted gamma-ray detectors can provide law enforcement officials the means to quickly and accurately detect, identify, and locate radiological threats over a wide geographical area. The ability to accurately distinguish radiological threat-generated gamma-ray signatures from background gamma radiation in real time is essential in order to realize this potential. This problem is non-trivial, especially in urban environments for which the background may change very rapidly during flight. This exacerbates the challenge of estimating background due to the poor counting statistics inherent in real-time airborne gamma-ray spectroscopy measurements. To address this, we have developed a new technique for real-time estimation ofmore » background gamma radiation from aerial measurements. This method is built upon on the noise-adjusted singular value decomposition (NASVD) technique that was previously developed for estimating the potassium (K), uranium (U), and thorium (T) concentrations in soil post-flight. The method can be calibrated using K, U, and T spectra determined from radiation transport simulations along with basis functions, which may be determined empirically by applying maximum likelihood estimation (MLE) to previously measured airborne gamma-ray spectra. The method was applied to both measured and simulated airborne gamma-ray spectra, with and without man-made radiological source injections. Compared to schemes based on simple averaging, this technique was less sensitive to background contamination from the injected man-made sources and may be particularly useful when the gamma-ray background frequently changes during the course of the flight.« less

  4. Development of a digital method for neutron/gamma-ray discrimination based on matched filtering

    NASA Astrophysics Data System (ADS)

    Korolczuk, S.; Linczuk, M.; Romaniuk, R.; Zychor, I.

    2016-09-01

    Neutron/gamma-ray discrimination is crucial for measurements with detectors sensitive to both neutron and gamma-ray radiation. Different techniques to discriminate between neutrons and gamma-rays based on pulse shape analysis are widely used in many applications, e.g., homeland security, radiation dosimetry, environmental monitoring, fusion experiments, nuclear spectroscopy. A common requirement is to improve a radiation detection level with a high detection reliability. Modern electronic components, such as high speed analog to digital converters and powerful programmable digital circuits for signal processing, allow us to develop a fully digital measurement system. With this solution it is possible to optimize digital signal processing algorithms without changing any electronic components in an acquisition signal path. We report on results obtained with a digital acquisition system DNG@NCBJ designed at the National Centre for Nuclear Research. A 2'' × 2'' EJ309 liquid scintillator was used to register mixed neutron and gamma-ray radiation from PuBe sources. A dedicated algorithm for pulse shape discrimination, based on real-time filtering, was developed and implemented in hardware.

  5. Measurement of natural radionuclides in phosphgypsum using an anti-cosmic gamma-ray spectrometer.

    PubMed

    Ferreux, Laurent; Moutard, Gérard; Branger, Thierry

    2009-05-01

    Gamma-ray spectrometry measurements have been carried out to determine the activity of natural radionuclides in a phosphogypsum sample included in a specific tight container. The gamma spectrometer includes an N-type coaxial high-purity germanium (HPGe) detector equipped with an anti-cosmic system. This measurement required the determination of linear attenuation coefficients of phosphogypsum to calculate self-absorption correction between efficiency calibration conditions and measurement ones. The results are given for the three natural chains and for (40)K, in term of specific activity/g of dry material, ranging from a few Bq kg(-1) to a few hundreds Bq kg(-1). The equilibrium within the different families and the (235)U/(238)U ratio are discussed.

  6. Development and application of marine gamma-ray measurements: a review.

    PubMed

    Jones, D G

    2001-01-01

    The development of instruments to measure gamma radiation in the marine environment, particularly on the sea floor, and the range of uses to which they have been put is reviewed. Since the first steps in the late 1950s, systems have been developed in at least 10 countries with the main thrust occurring in the 1970s. Development has continued up to the present, primarily in Europe and the USA. Marine gamma-ray spectrometers have been used for a range of applications including the mapping of rocks and unconsolidated sediments, mineral exploration (mainly for heavy minerals and phosphorites), sediment transport studies and investigations in relation to discharged and dumped nuclear wastes and at nuclear weapon test sites.

  7. Effects of gamma-sterilization on the physicochemical properties of natural sediments

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bank, Tracy L; Madden, Andrew; Baldwin, Mark E

    2008-06-01

    Batch U(VI) sorption/reduction experiments were completed on sterilized and non-sterilized sediment samples to elucidate biological and geochemical reduction mechanisms. Results from X-ray absorption near-edge structure (XANES) spectroscopy revealed that {gamma}-sterilized sediments were actually better sorbents of U(VI), despite the absence of any measurable biological activity. These results indicate that {gamma}-irradiation induced significant physico-chemical changes in the sediment which is contrary to numerous other studies identifying {gamma}-sterilization as an effective and minimally invasive technique. To identify the extent and method of alteration of the soil as a result of {gamma}-sterilization, untreated soil samples, physically separated size fractions, and chemically extracted fractionsmore » of the soil were analyzed pre- and post-sterilization. The effects of sterilization on mineralogy, pH, natural organic matter (NOM), cation exchange capacity (CEC), and iron oxidation state were determined. Results indicated that major mineralogy of the clay and whole sediment samples was unchanged. Sediment pH decreased only slightly with {gamma}-irradiation; however, irradiation produced a significant decrease in CEC of the untreated sediments and affected both the organic and inorganic fractions. Moessbauer spectra of non-sterile and {gamma}-sterilized sediments measured more reduced iron present in {gamma}-sterilized sediments compared to non-sterile samples. Our results suggest that sterilization by {gamma}-irradiation induced iron reduction that may have increased the sorption and/or reduction of U(VI) onto these sediments. However, Moessbauer and batch sorption data are somewhat contradictory, the former indicates that the iron oxide or iron hydroxide minerals are more significantly reduced while the later indicates that reduced clay minerals account for greater sorption of U(VI).« less

  8. Quantitative fiber-optic Raman spectroscopy for tissue Raman measurements

    NASA Astrophysics Data System (ADS)

    Duraipandian, Shiyamala; Bergholt, Mads; Zheng, Wei; Huang, Zhiwei

    2014-03-01

    Molecular profiling of tissue using near-infrared (NIR) Raman spectroscopy has shown great promise for in vivo detection and prognostication of cancer. The Raman spectra measured from the tissue generally contain fundamental information about the absolute biomolecular concentrations in tissue and its changes associated with disease transformation. However, producing analogues tissue Raman spectra present a great technical challenge. In this preliminary study, we propose a method to ensure the reproducible tissue Raman measurements and validated with the in vivo Raman spectra (n=150) of inner lip acquired using different laser powers (i.e., 30 and 60 mW). A rapid Raman spectroscopy system coupled with a ball-lens fiber-optic Raman probe was utilized for tissue Raman measurements. The investigational results showed that the variations between the spectra measured with different laser powers are almost negligible, facilitating the quantitative analysis of tissue Raman measurements in vivo.

  9. Study of Vis/NIR spectroscopy measurement on acidity of yogurt

    NASA Astrophysics Data System (ADS)

    He, Yong; Feng, Shuijuan; Wu, Di; Li, Xiaoli

    2006-09-01

    A fast measurement of pH of yogurt using Vis/NIR-spectroscopy techniques was established in order to measuring the acidity of yogurt rapidly. 27 samples selected separately from five different brands of yogurt were measured by Vis/NIR-spectroscopy. The pH of yogurt on positions scanned by spectrum was measured by a pH meter. The mathematical model between pH and Vis/NIR spectral measurements was established and developed based on partial least squares (PLS) by using Unscramble V9.2. Then 25 unknown samples from 5 different brands were predicted based on the mathematical model. The result shows that The correlation coefficient of pH based on PLS model is more than 0.890, and standard error of calibration (SEC) is 0.037, standard error of prediction (SEP) is 0.043. Through predicting the pH of 25 samples of yogurt from 5 different brands, the correlation coefficient between predictive value and measured value of those samples is more than 0918. The results show the good to excellent prediction performances. The Vis/NIR spectroscopy technique had a significant greater accuracy for determining the value of pH. It was concluded that the VisINIRS measurement technique can be used to measure pH of yogurt fast and accurately, and a new method for the measurement of pH of yogurt was established.

  10. Operando Positron Annihilation Gamma Spectrometer (OPAGS)

    NASA Astrophysics Data System (ADS)

    Satyal, S.; Shastry, K.; Mukherjee, S.; Weiss, A. H.

    2009-03-01

    Surface properties measured under UHV conditions cannot be extended to surfaces interacting with gases under realistic pressures due to surface reconstruction and other strong perturbations of the surface. Surface probing techniques require UHV conditions to perform efficiently and avoid data loss due to scattering of outgoing particles. This poster describes the design of an Operando Positron Annihilation Gamma Spectrometer (OPAGS) currently under construction at the University of Texas at Arlington. The new system will be capable of obtaining surface and defect specific chemical and charge state information from surfaces under realistic pressures. Differential pumping will be used to maintain the sample in a gas environment while the rest of the beam is under UHV. Elemental content of the surface interacting with the gas environment will be determined from the Doppler broadened gamma spectra. This system will also include a time of flight (TOF) Auger spectrometer which correlates with the results of the Doppler measurements at lower pressures. By employing the unique capabilities of OPAGS together with those of the TOF PAES spectroscopy the charge transfer mechanisms at the surface in catalytic systems can be understood.

  11. Venus Measurements by the MESSENGER Gamma-Ray and X-Ray Spectrometers

    NASA Astrophysics Data System (ADS)

    Rhodes, E. A.; Starr, R. D.; Goldsten, J. O.; Schlemm, C. E.; Boynton, W. V.

    2007-12-01

    The Gamma-Ray Spectrometer (GRS), which is a part of the Gamma-Ray and Neutron Spectrometer Instrument, and the X-Ray Spectrometer (XRS) on the MESSENGER spacecraft made calibration measurements during the Venus flyby on June 5, 2007. The purpose of these instruments is to determine elemental abundances on the surface of Mercury. The GRS measures gamma-rays emitted from element interactions with cosmic rays impinging on the surface, while the XRS measures X-ray emissions induced on the surface by the incident solar flux. The GRS sensor is a high-resolution high-purity Ge detector cooled by a Stirling cryocooler, surrounded by a borated-plastic anticoincidence shield. The GRS is sensitive to gamma-rays up to ~10 MeV and can identify most major elements, sampling down to depths of about ten centimeters. Only the shield was powered on for this flyby in order to conserve cooler lifetime. Gamma-rays were observed coming from Venus as well as from the spacecraft. Although the Venus gamma-rays originate from its thick atmosphere rather than its surface, the GRS data from this encounter will provide useful calibration data from a source of known composition. In particular, the data will be useful for determining GRS sensitivity and pointing options for the Mercury flybys, the first of which will be in January 2008. The X-ray spectrum of a planetary surface is dominated by a combination of the fluorescence and scattered solar X-rays. The most prominent fluorescent lines are the Kα lines from the major elements Mg, Al, Si, S, Ca, Ti, and Fe (1-10 keV). The sampling depth is less than 100 u m. The XRS is similar in design to experiments flown on Apollo 15 and 16 and the NEAR-Shoemaker mission. Three large-area gas-proportional counters view the planet, and a small Si-PIN detector mounted on the spacecraft sunshade monitors the Sun. The energy resolution of the gas proportional counters (~850 eV at 5.9 keV) is sufficient to resolve the X-ray lines above 2 keV, but Al and Mg

  12. Gamma-based Measurement of ``Dark Mix'' in ICF Capsules

    NASA Astrophysics Data System (ADS)

    Meaney, Kevin; Herrmann, H.; Kim, Yh; Zylstra, Ab; Geppert-Kleinrath, H.; Hoffman, Nm; Yi, As

    2017-10-01

    Mix of capsule ablator material into the fusion fuel is a source of yield degradation in inertial confinement fusion. Jetting or chunk mix, such as the elusive ``meteors'' that have been observed at NIF, can be difficult to diagnose because the chunks may not get hot enough to excite dopant x-rays, nor atomized enough for separated-reactants to fuse. Using the gamma reaction history (GRH-6m) diagnostic, (n,n') gammas from strategically placed carbon layer within a beryllium capsule gives a measure of the time-resolved areal density of this carbon during the burn and hence an indication of the compression and spatial distribution of this layer. As the carbon moves further from the fuel, the areal density nominally decreases as 1/r2 for unablated material. However, mix of this carbon into the cold dense fuel layer or hot spot will have a significant effect on the carbon gamma signal. Different types of mix (e.g., jetting, Rayleigh-Taylor fingers, diffusive, ...) as well as features that can seed this mix (eg., tents, fill,...) will be discussed along with their expected effect on the carbon signal. The design for upcoming OMEGA shots, which will demonstrate this technique, and the potential for use on the NIF will be presented.

  13. Gamma radiation effects on polydimethylsiloxane rubber foams under different radiation conditions

    NASA Astrophysics Data System (ADS)

    Sui, H. L.; Liu, X. Y.; Zhong, F. C.; Li, X. Y.; Wang, L.; Ju, X.

    2013-07-01

    Polydimethylsiloxane rubber foams were irradiated by gamma ray under different radiation conditions designed by orthogonal design method. Compression set measurement, infrared attenuated total reflectance spectroscopy (ATR) and X-ray induced photoelectron spectroscopy (XPS) were used. Three aging factors' influence effects on the mechanical property and chemical structure were studied. It was found that among the three factors and the chosen levels, both properties were affected most by radiation dose, while radiation dose rate had no obvious influence on both properties. The stiffening of the rubber foams was caused by cross-linking reactions in the Si-CH3. At the same radiation dose, the rigidity of the foams irradiated in air was lower than that in nitrogen. When polydimethylsiloxane was irradiated at a high dose in sealed nitrogen atmosphere, carbon element distribution would be changed. Hydrocarbons produced by gamma ray in the sealed tube would make the carbon content in the skin-deep higher than that in the middle, which indicated that polydimethylsiloxane rubber foams storing in a sealed atmosphere filled with enough hydrocarbons should be helpful to extend the service life.

  14. HEAO C-1 gamma-ray spectrometer. [experimental design

    NASA Technical Reports Server (NTRS)

    Mahoney, W. A.; Ling, J. C.; Willett, J. B.; Jacobson, A. S.

    1978-01-01

    The gamma-ray spectroscopy experiment to be launched on the third High Energy Astronomy Observatory (HEAO C) will perform a complete sky search for narrow gamma-ray line emission to the level of about 00001 photons/sq cm -sec for steady point sources. The design of this experiment and its performance based on testing and calibration to date are discussed.

  15. Fermi Large Area Telescope Measurements of the Diffuse Gamma-Ray Emission at Intermediate Galactic Latitudes

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2009-12-16

    We report that the diffuse galactic γ-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess γ-ray emission ≳1 GeV relative to diffuse galactic γ-ray emission models consistent with directly measured CR spectra (the so-called “EGRET GeV excess”). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse γ -ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV andmore » galactic latitudes 10° ≤ | b | ≤ 20°. Finally, the LAT spectrum for this region of the sky is well reproduced by a diffuse galactic γ-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.« less

  16. Effects of gamma oryzanol supplementation on anthropometric measurements & muscular strength in healthy males following chronic resistance training.

    PubMed

    Eslami, Saghar; Esa, Norhaizan Mohd; Marandi, Seyed Mohammad; Ghasemi, Gholamali; Eslami, Sepehr

    2014-06-01

    Enhanced muscle strength is seen when resistance exercise is combined with the consumption of nutritional supplements. Although there is a limited number of studies available about the efficacy of gamma oryzanol supplementation with resistance exercise in humans, but its usage as a nutritional supplement for strength is common in athletes. The aim of this study was to determine the effects of gamma oryzanol supplementation during 9-week resistance training on muscular strength and anthropometric measurements of young healthy males. In this double-blind clinical trial, changes of anthropometric measurements and muscular strength were studied after chronic resistance exercise and gamma oryzanol supplementation in 30 healthy volunteers (16 in supplement and 14 in placebo). Each day, gamma oryzanol supplement (600 mg) and placebo (the same amount of lactose) were consumed after training. The participants exercised with 80 per cent 1-Repetition Maximum (1-RM), for one hour and four days/week. Anthropometric measurements and subjects' 1-RM for muscular strength were determined at the commencement and end of the 9-week study. There was no significant difference between the baseline characteristics and target variables at baseline between the two groups. After gamma oryzanol supplementation, there was no significant difference in the means of anthropometric and skin fold measurements between the supplement and placebo groups. However, there were significant differences between the supplement and placebo groups for 1-RM of bench press and leg curl, which showed that gamma oryzanol improved muscle strength following resistance training. Our findings indicated that 600 mg/day gamma oryzanol supplementation during the 9-week resistance training did not change anthropometric and body measurements, but it increased muscular strength in young healthy males. Further, studies need to be done in trained athletes, women, and in patients who suffer from muscular fatigue.

  17. Effects of gamma oryzanol supplementation on anthropometric measurements & muscular strength in healthy males following chronic resistance training

    PubMed Central

    Eslami, Saghar; Esa, Norhaizan Mohd; Marandi, Seyed Mohammad; Ghasemi, Gholamali; Eslami, Sepehr

    2014-01-01

    Background & objectives: Enhanced muscle strength is seen when resistance exercise is combined with the consumption of nutritional supplements. Although there is a limited number of studies available about the efficacy of gamma oryzanol supplementation with resistance exercise in humans, but its usage as a nutritional supplement for strength is common in athletes. The aim of this study was to determine the effects of gamma oryzanol supplementation during 9-week resistance training on muscular strength and anthropometric measurements of young healthy males. Methods: In this double-blind clinical trial, changes of anthropometric measurements and muscular strength were studied after chronic resistance exercise and gamma oryzanol supplementation in 30 healthy volunteers (16 in supplement and 14 in placebo). Each day, gamma oryzanol supplement (600 mg) and placebo (the same amount of lactose) were consumed after training. The participants exercised with 80 per cent 1-Repetition Maximum (1-RM), for one hour and four days/week. Anthropometric measurements and subjects’ 1-RM for muscular strength were determined at the commencement and end of the 9-week study. Results: There was no significant difference between the baseline characteristics and target variables at baseline between the two groups. After gamma oryzanol supplementation, there was no significant difference in the means of anthropometric and skin fold measurements between the supplement and placebo groups. However, there were significant differences between the supplement and placebo groups for 1-RM of bench press and leg curl, which showed that gamma oryzanol improved muscle strength following resistance training. Interpretation & conclusions: Our findings indicated that 600 mg/day gamma oryzanol supplementation during the 9-week resistance training did not change anthropometric and body measurements, but it increased muscular strength in young healthy males. Further, studies need to be done in trained

  18. Total absorption γ -ray spectroscopy of the β -delayed neutron emitters Br 87 , Br 88 , and Rb 94

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Valencia, E.; Tain, J. L.; Algora, A.

    2017-02-01

    We investigate the decay of Br-87,Br-88 and Rb-94 using total absorption gamma-ray spectroscopy. These important fission products are beta-delayed neutron emitters. Our data show considerable beta gamma intensity, so far unobserved in high-resolution gamma-ray spectroscopy, from states at high excitation energy. We also find significant differences with the beta intensity that can be deduced from existing measurements of the beta spectrum. We evaluate the impact of the present data on reactor decay heat using summation calculations. Although the effect is relatively small it helps to reduce the discrepancy between calculations and integral measurements of the photon component for U-235 fissionmore » at cooling times in the range 1-100 s. We also use summation calculations to evaluate the impact of present data on reactor antineutrino spectra. We find a significant effect at antineutrino energies in the range of 5 to 9 MeV. In addition, we observe an unexpected strong probability for. emission from neutron unbound states populated in the daughter nucleus. The. branching is compared to Hauser-Feshbach calculations, which allow one to explain the large value for bromine isotopes as due to nuclear structure. However the branching for Rb-94, although much smaller, hints of the need to increase the radiative width gamma by one order of magnitude. This increase in gamma would lead to a similar increase in the calculated (n, gamma) cross section for this very neutron-rich nucleus with a potential impact on r process abundance calculations.« less

  19. Gamma-Ray Attenuation Measurements as a Laboratory Experiment: Some Remarks

    ERIC Educational Resources Information Center

    Adamides, E.; Koutroubas, S. K.; Moshonas, N.; Yiasemides, K.

    2011-01-01

    In this article we make some significant remarks on the experimental study of the absorption of gamma radiation passing through matter. These remarks have to do with the seemingly unexpected trend of the measured intensity of radiation versus the thickness of the absorber, which puzzles students and its explanation eludes many laboratory…

  20. Characterization of uranium bearing material using x-ray fluorescence and direct gamma-rays measurement techniques

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mujaini, M., E-mail: madihah@uniten.edu.my; Chankow, N.; Yusoff, M. Z.

    2016-01-22

    Uranium ore can be easily detected due to various gamma-ray energies emitted from uranium daughters particularly from {sup 238}U daughters such as {sup 214}Bi, {sup 214}Pb and {sup 226}Ra. After uranium is extracted from uranium ore, only low energy gamma-rays emitted from {sup 235}U may be detected if the detector is placed in close contact to the specimen. In this research, identification and characterization of uranium bearing materials is experimentally investigated using direct measurement of gamma-rays from {sup 235}U in combination with the x-ray fluorescence (XRF) technique. Measurement of gamma-rays can be conducted by using high purity germanium (HPGe) detectormore » or cadmium telluride (CdTe) detector while a {sup 57}Coradioisotope-excited XRF spectrometer using CdTe detector is used for elemental analysis. The proposed technique was tested with various uranium bearing specimens containing natural, depleted and enriched uranium in both metallic and powder forms.« less

  1. MEASUREMENTS OF GAMMA-RAY DOSES OF DIFFERENT RADIOISOTOPES BY THE TEST-FILM METHOD (in German)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Domanus, J.; Halski, L.

    The test-film method seems to be most suitable for systematic, periodical measurements of individual doses of ionizing radiation. Persons handling radioisotopes are irradiated with gamma rays of different energies. The energy of gamma radiation lies within much broader limits than is the case with x rays. Therefore it was necessary to check whether the test-film method is suitable for measuring doses of gamma-rays of such different energies and to choose the proper combination of film and screen to reach the necessary measuring range. Polish films, Foton Rentgen and Foton Rentgen Super and films from the German Democratic Republic, Agfa Texomore » R and Agfa Texo S were tested. Expositions were made without intensifying screens as well as with lead and fluorescent screens. The investigations showed that for dosimetric purposes the Foton Rentgen Super films are most suitable. However, not one of the film-screen combinations gave satisfactory results for radioisotopes with radiation of different energies. In such a case the test-film method gives only approximate results. If, on the contrary, gamma energies do not differ greatly, the test- film method proves to be quite good. (auth)« less

  2. Investigation of gamma radiation induced changes in local structure of borosilicate glass by TDPAC and EXAFS

    NASA Astrophysics Data System (ADS)

    Kumar, Ashwani; Nayak, C.; Rajput, P.; Mishra, R. K.; Bhattacharyya, D.; Kaushik, C. P.; Tomar, B. S.

    2016-12-01

    Gamma radiation induced changes in local structure around the probe atom (Hafnium) were investigated in sodium barium borosilicate (NBS) glass, used for immobilization of high level liquid waste generated from the reprocessing plant at Trombay, Mumbai. The (NBS) glass was doped with 181Hf as a probe for time differential perturbed angular correlation (TDPAC) spectroscopy studies, while for studies using extended X-ray absorption fine structure (EXAFS) spectroscopy, the same was doped with 0.5 and 2 % (mole %) hafnium oxide. The irradiated as well as un-irradiated glass samples were studied by TDPAC and EXAFS techniques to obtain information about the changes (if any) around the probe atom due to gamma irradiation. TDPAC spectra of unirradiated and irradiated glasses were similar and reminescent of amorphous materials, indicating negligible effect of gamma radiation on the microstructure around Hafnium probe atom, though the quaqdrupole interaction frequency ( ω Q) and asymmetry parameter ( η) did show a marginal decrease in the irradiated glass compared to that in the unirradiated glass. EXAFS measurements showed a slight decrease in the Hf-O bond distance upon gamma irradiation of Hf doped NBS glass indicating densification of the glass matrix, while the cordination number around hafnium remains unchanged.

  3. Gamma-ray Full Spectrum Analysis for Environmental Radioactivity by HPGe Detector

    NASA Astrophysics Data System (ADS)

    Jeong, Meeyoung; Lee, Kyeong Beom; Kim, Kyeong Ja; Lee, Min-Kie; Han, Ju-Bong

    2014-12-01

    Odyssey, one of the NASA¡¯s Mars exploration program and SELENE (Kaguya), a Japanese lunar orbiting spacecraft have a payload of Gamma-Ray Spectrometer (GRS) for analyzing radioactive chemical elements of the atmosphere and the surface. In these days, gamma-ray spectroscopy with a High-Purity Germanium (HPGe) detector has been widely used for the activity measurements of natural radionuclides contained in the soil of the Earth. The energy spectra obtained by the HPGe detectors have been generally analyzed by means of the Window Analysis (WA) method. In this method, activity concentrations are determined by using the net counts of energy window around individual peaks. Meanwhile, an alternative method, the so-called Full Spectrum Analysis (FSA) method uses count numbers not only from full-absorption peaks but from the contributions of Compton scattering due to gamma-rays. Consequently, while it takes a substantial time to obtain a statistically significant result in the WA method, the FSA method requires a much shorter time to reach the same level of the statistical significance. This study shows the validation results of FSA method. We have compared the concentration of radioactivity of 40K, 232Th and 238U in the soil measured by the WA method and the FSA method, respectively. The gamma-ray spectrum of reference materials (RGU and RGTh, KCl) and soil samples were measured by the 120% HPGe detector with cosmic muon veto detector. According to the comparison result of activity concentrations between the FSA and the WA, we could conclude that FSA method is validated against the WA method. This study implies that the FSA method can be used in a harsh measurement environment, such as the gamma-ray measurement in the Moon, in which the level of statistical significance is usually required in a much shorter data acquisition time than the WA method.

  4. Measurement of the 235U Induced Fission Gamma-ray Spectrum as an Active Non-destructive Assay of Fresh Nucleear Fuel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sarnoski, Sarah E.; Fast, James E.; Fulsom, Bryan G.

    2017-07-17

    Non-destructive assay is a powerful tool the International Atomic Energy Agency (IAEA) employs to verify adherence to safeguards agreements. Current IAEA veri- cation techniques for fresh nuclear fuel include passive gamma-ray spectroscopy to determine fuel enrichment. This technique suers from self-shielding and lakes the percision to detect diversion of central fuel rods. The aim of this research is to develop a new, more capable non-destructive analysis technique using active neutron interroga- tion of fuel assemblies and determining the yields of short-lived ssion products from high-resolution gamma-ray spectroscopy using high-purity germanium (HPGe). This paper reports results from irradiation of a onemore » meter tall mock fresh fuel assembly with low enriched uranium (LEU) or depleted uranium (DU) rods using a down-scattered deuterium-tritium (D-T) neutron source. Both prompt and delayed gamma-ray spec- tra were collected as time-stamped list-mode data in a coax detector and without list mode data in a planar strip detector. No dierentiating signatures were observed in the prompt spectra in either detector; however, both detectors observed several short-lived ssion product signatures in LEU and not DU fuel, indicating that this technique has potential for determination of enrichment of fresh fuel assemblies. There were eight unique ssion products observed in the LEU spectra with the coax detector spectra, and three ssion products were observed in the LEU spectra with the strip detector.« less

  5. Real-time airborne gamma-ray background estimation using NASVD with MLE and radiation transport for calibration

    NASA Astrophysics Data System (ADS)

    Kulisek, J. A.; Schweppe, J. E.; Stave, S. C.; Bernacki, B. E.; Jordan, D. V.; Stewart, T. N.; Seifert, C. E.; Kernan, W. J.

    2015-06-01

    Helicopter-mounted gamma-ray detectors can provide law enforcement officials the means to quickly and accurately detect, identify, and locate radiological threats over a wide geographical area. The ability to accurately distinguish radiological threat-generated gamma-ray signatures from background gamma radiation in real time is essential in order to realize this potential. This problem is non-trivial, especially in urban environments for which the background may change very rapidly during flight. This exacerbates the challenge of estimating background due to the poor counting statistics inherent in real-time airborne gamma-ray spectroscopy measurements. To address this challenge, we have developed a new technique for real-time estimation of background gamma radiation from aerial measurements without the need for human analyst intervention. The method can be calibrated using radiation transport simulations along with data from previous flights over areas for which the isotopic composition need not be known. Over the examined measured and simulated data sets, the method generated accurate background estimates even in the presence of a strong, 60Co source. The potential to track large and abrupt changes in background spectral shape and magnitude was demonstrated. The method can be implemented fairly easily in most modern computing languages and environments.

  6. Moessbauer spectroscopy study on the corrosion resistance of plasma nitrided ASTM F138 stainless steel in chloride solution

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Souza, S.D. de; Olzon-Dionysio, M., E-mail: dmod@df.ufscar.br; Basso, R.L.O.

    2010-10-15

    Plasma nitriding of ASTM F138 stainless steel samples has been carried out using dc glow discharge under 80% H{sub 2}-20% N{sub 2} gas mixture, at 673 K, and 2, 4, and 7 h time intervals, in order to investigate the influence of treatment time on the microstructure and the corrosion resistance properties. The samples were characterized by scanning electron microscopy, glancing angle X-ray diffraction and conversion electron Moessbauer spectroscopy, besides electrochemical tests in NaCl aerated solution. A modified layer of about 6 {mu}m was observed for all the nitrided samples, independent of nitriding time. The X-ray diffraction analysis shows broadmore » {gamma}{sub N} phase peaks, signifying a great degree of nitrogen supersaturation. Besides {gamma}{sub N,} the Moessbauer spectroscopy results indicated the occurrence of {gamma}' and {epsilon} phases, as well as some other less important phases. Corrosion measurements demonstrate that the plasma nitriding time affects the corrosion resistance and the best performance is reached at 4 h treatment. It seems that the {epsilon}/{gamma}' fraction ratio plays an important role on the resistance corrosion. Additionally, the Moessbauer spectroscopy was decisive in this study, since it was able to identify and quantify the iron phases that influence the corrosion resistance of plasma nitrided ASTM F138 samples.« less

  7. Tests and foreseen developments of fibered-OSLD gamma heating measurements in low-power reactors

    NASA Astrophysics Data System (ADS)

    Gruel, A.; Guillou, M. Le; Blaise, P.; Destouches, C.; Magne, S.

    2018-01-01

    In this paper are presented test measurements of a fibered-OSLD system performed during a dedicated experimental phase in EOLE zero-power reactor. The measurement setup consists of an OSLD crystal connected onto the extremity of an optical fiber and a laser stimulation system, manufactured by the CEA/LIST in Saclay. The OSL sensor is remotely stimulated via an optical fiber using a diode-pumped solid-state laser. The OSL light is collected and guided back along the same fiber to a photomultiplier tube. Results obtained using this system are compared to usual gamma heating measurement protocol using OSLD pellets. The presence of induced radio-luminescence in the OSLD during the irradiation was also observed and could be used to monitor the gamma flux. The feasibility of remote measurements is achieved, whereas further developments could be conducted to improve this technique since the readout procedure still requires to withdraw the OSLD off the gamma flux (hence from the core) on account of the dose rate (around a few Gy.h-1), and the readout time remains quite long for on-line applications. Several improvements are foreseen, and will be tested in the forthcoming years.

  8. Optimal measurement counting time and statistics in gamma spectrometry analysis: The time balance

    NASA Astrophysics Data System (ADS)

    Joel, Guembou Shouop Cebastien; Penabei, Samafou; Maurice, Ndontchueng Moyo; Gregoire, Chene; Jilbert, Nguelem Mekontso Eric; Didier, Takoukam Serge; Werner, Volker; David, Strivay

    2017-01-01

    The optimal measurement counting time for gamma-ray spectrometry analysis using HPGe detectors was determined in our laboratory by comparing twelve hours measurement counting time at day and twelve hours measurement counting time at night. The day spectrum does not fully cover the night spectrum for the same sample. It is observed that the perturbation come to the sun-light. After several investigations became clearer: to remove all effects of radiation from outside (earth, the sun, and universe) our system, it is necessary to measure the background for 24, 48 or 72 hours. In the same way, the samples have to be measured for 24, 48 or 72 hours to be safe to be purified the measurement (equality of day and night measurement). It is also possible to not use the background of the winter in summer. Depend on to the energy of radionuclide we seek, it is clear that the most important steps of a gamma spectrometry measurement are the preparation of the sample and the calibration of the detector.

  9. A system for the measurement of delayed neutrons and gammas from special nuclear materials

    DOE PAGES

    Andrews, M. T.; Corcoran, E. C.; Goorley, J. T.; ...

    2014-11-27

    The delayed neutron counting (DNC) system at the Royal Military College of Canada has been upgraded to accommodate concurrent delayed neutron and gamma measurements. This delayed neutron and gamma counting (DNGC) system uses a SLOWPOKE-2 reactor to irradiate fissile materials before their transfer to a counting arrangement consisting of six ³He and one HPGe detector. The application of this system is demonstrated in an example where delayed neutron and gamma emissions are used in complement to examine ²³³U content and determine fissile mass with an average relative error and accuracy of -2.2 and 1.5 %, respectively.

  10. Neutron and gamma-ray dose measurements at various distances from the Little Boy replica

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Huntzinger, C.J.; Hankins, D.E.

    We measured neutron and gamma-ray dose rates at various distances from the Little Boy-Comet Critical Assembly at Los Alamos National Laboratory (LANL) in April of 1983. The Little Boy-Comet Assembly is a replica of the atomic weapon detonated over Hiroshima, designed to be operated at various steady-state power levels. The selected distances for measurement ranged from 107 m to 567 m. Gamma-ray measurements were made with a Reuter-Stokes environmental ionization chamber which has a sensitivity of 1.0 ..mu..R/hour. Neutron measurements were made with a pulsed-source remmeter which has a sensitivity of 0.1 ..mu..rem/hour, designed and built at Lawrence Livermore Nationalmore » Laboratory (LLNL). 12 references, 7 figures, 6 tables.« less

  11. Flow velocity measurements with stimulated Rayleigh-Brillouin-gain spectroscopy

    NASA Technical Reports Server (NTRS)

    Herring, G. C.; Moosmueller, H.; Lee, S. A.; She, C. Y.

    1983-01-01

    Using stimulated Rayleigh-Brillouin-gain spectroscopy, velocity measurements in an atmospheric-pressure subsonic nitrogen flow with 10 percent uncertainty have been conducted. It is shown that the accuracy of the velocity measurements increases with gas pressure, making this spectroscopic technique ideal for measuring velocity and other parameters of high-pressure (greater than 1-atm) atomic or molecular flows.

  12. Constraints on cosmological dark matter annihilation from the Fermi-LAT isotropic diffuse gamma-ray measurement

    DOE PAGES

    Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

    2010-04-01

    The first published Fermi large area telescope (Fermi-LAT) measurement of the isotropic diffuse gamma-ray emission is in good agreement with a single power law, and is not showing any signature of a dominant contribution from dark matter sources in the energy range from 20 to 100 GeV. Here, we use the absolute size and spectral shape of this measured flux to derive cross section limits on three types of generic dark matter candidates: annihilating into quarks, charged leptons and monochromatic photons. Predicted gamma-ray fluxes from annihilating dark matter are strongly affected by the underlying distribution of dark matter, and bymore » using different available results of matter structure formation we assess these uncertainties. We also quantify how the dark matter constraints depend on the assumed conventional backgrounds and on the Universe's transparency to high-energy gamma-rays. In reasonable background and dark matter structure scenarios (but not in all scenarios we consider) it is possible to exclude models proposed to explain the excess of electrons and positrons measured by the Fermi-LAT and PAMELA experiments. Derived limits also start to probe cross sections expected from thermally produced relics (e.g. in minimal supersymmetry models) annihilating predominantly into quarks. Finally, for the monochromatic gamma-ray signature, the current measurement constrains only dark matter scenarios with very strong signals.« less

  13. Measurement of beta-plus emitters by gamma-ray spectrometry.

    PubMed

    Lépy, Marie-Christine; Cassette, Philippe; Ferreux, Laurent

    2010-01-01

    The activity measurement of beta-plus emitters by gamma-ray spectrometry is studied. Experimental measurements are performed with (22)Na, (65)Zn and (64)Cu with sources included in a lead container. For these nuclides, the activity can be derived both from one photon emission peak and from the 511 keV annihilation peak, including annihilation in-flight correction and geometry correction computed by Monte Carlo simulation. The activity values obtained using the two types of peaks show satisfying agreement. The extension of the method to volume sources is discussed. Copyright 2009 Elsevier Ltd. All rights reserved.

  14. Investigation of Martian H2O and CO2 via orbital gamma ray spectroscopy

    NASA Technical Reports Server (NTRS)

    Evans, Larry G.; Squyres, Steven W.

    1987-01-01

    The capability of an orbital gamma ray spectrometer to address presently unanswered questions concerning H2O and CO2 on Mars is investigated. The gamma ray signal produced by the Martian atmosphere and by several simple models of Martian surface materials is calculated. Results are reported for: (1) the production of neutrons in the atmosphere and in the subsurface material by cosmic ray interactions, (2) the scattering of neutrons and the resultant neutron energy spectrum and spatial distributions, (3) the reproduction of gamma rays by neutron prompt capture and nonelastic scatter reactions, (4) the production of gamma rays by natural radionuclides, (5) the attenuation of the gamma ray signal by passage through surface materials and the Martian atmosphere, (6) the production of the gamma ray continuum background, and (7) the uncertainty in gamma ray line strengths that results from the combined signal and background observed by the detector.

  15. Measurement of atmospheric ozone by cavity ring-down spectroscopy.

    PubMed

    Washenfelder, R A; Wagner, N L; Dube, W P; Brown, S S

    2011-04-01

    Ozone plays a key role in both the Earth's radiative budget and photochemistry. Accurate, robust analytical techniques for measuring its atmospheric abundance are of critical importance. Cavity ring-down spectroscopy has been successfully used for sensitive and accurate measurements of many atmospheric species. However, this technique has not been used for atmospheric measurements of ozone, because the strongest ozone absorption bands occur in the ultraviolet spectral region, where Rayleigh and Mie scattering cause significant cavity losses and dielectric mirror reflectivities are limited. Here, we describe a compact instrument that measures O3 by chemical conversion to NO2 in excess NO, with subsequent detection by cavity ring-down spectroscopy. This method provides a simple, accurate, and high-precision measurement of atmospheric ozone. The instrument consists of two channels. The sum of NO2 and converted O3 (defined as Ox) is measured in the first channel, while NO2 alone is measured in the second channel. NO2 is directly detected in each channel by cavity ring-down spectroscopy with a laser diode light source at 404 nm. The limit of detection for O3 is 26 pptv (2 sigma precision) at 1 s time resolution. The accuracy of the measurement is ±2.2%, with the largest uncertainty being the effective NO2 absorption cross-section. The linear dynamic range of the instrument has been verified from the detection limit to above 200 ppbv (r2>99.99%). The observed precision on signal (2 sigma) with 41 ppbv O3 is 130 pptv in 1 s. Comparison of this instrument to UV absorbance instruments for ambient O3 concentrations shows linear agreement (r2=99.1%) with slope of 1.012±0.002.

  16. Estimating irradiated nuclear fuel characteristics by nonlinear multivariate regression of simulated gamma-ray emissions

    NASA Astrophysics Data System (ADS)

    Åberg Lindell, M.; Andersson, P.; Grape, S.; Håkansson, A.; Thulin, M.

    2018-07-01

    In addition to verifying operator declared parameters of spent nuclear fuel, the ability to experimentally infer such parameters with a minimum of intrusiveness is of great interest and has been long-sought after in the nuclear safeguards community. It can also be anticipated that such ability would be of interest for quality assurance in e.g. recycling facilities in future Generation IV nuclear fuel cycles. One way to obtain information regarding spent nuclear fuel is to measure various gamma-ray intensities using high-resolution gamma-ray spectroscopy. While intensities from a few isotopes obtained from such measurements have traditionally been used pairwise, the approach in this work is to simultaneously analyze correlations between all available isotopes, using multivariate analysis techniques. Based on this approach, a methodology for inferring burnup, cooling time, and initial fissile content of PWR fuels using passive gamma-ray spectroscopy data has been investigated. PWR nuclear fuels, of UOX and MOX type, and their gamma-ray emissions, were simulated using the Monte Carlo code Serpent. Data comprising relative isotope activities was analyzed with decision trees and support vector machines, for predicting fuel parameters and their associated uncertainties. From this work it may be concluded that up to a cooling time of twenty years, the 95% prediction intervals of burnup, cooling time and initial fissile content could be inferred to within approximately 7 MWd/kgHM, 8 months, and 1.4 percentage points, respectively. An attempt aiming to estimate the plutonium content in spent UOX fuel, using the developed multivariate analysis model, is also presented. The results for Pu mass estimation are promising and call for further studies.

  17. Unfolding the fission prompt gamma-ray energy and multiplicity distribution measured by DANCE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chyzh, A; Wu, C Y; Bredeweg, T

    2010-10-16

    The nearly energy independence of the {gamma}-ray efficiency and multiplicity response for the DANCE array, the unusual characteristic elucidated in our early technical report (LLNL-TR-452298), gives one a unique opportunity to derive the true prompt {gamma}-ray energy and multiplicity distribution in fission from the measurement. This unfolding procedure for the experimental data will be described in details and examples will be given to demonstrate the feasibility of reconstruction of the true distribution.

  18. Analysis and recent advances in gamma heating measurements in MINERVE facility by using TLD and OSLD techniques

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Amharrak, H.; Di Salvo, J.; Lyoussi, A.

    2011-07-01

    The objective of this study is to develop nuclear heating measurement methods in Zero Power experimental reactors. This paper presents the analysis of Thermo-Luminescent Detector (TLD) and Optically Stimulated Luminescent Detectors (OSLD) experiments in the UO{sub 2} core of the MINERVE research reactor at the CEA Cadarache. The experimental sources of uncertainties on the gamma dose have been reduced by improving the conditions, as well as the repeatability, of the calibration step for each individual TLD. The interpretation of these measurements needs to take into account calculation of cavity correction factors, related to calibration and irradiation configurations, as well asmore » neutron corrections calculations. These calculations are based on Monte Carlo simulations of neutron-gamma and gamma-electron transport coupled particles. TLD and OSLD are positioned inside aluminum pillboxes. The comparison between calculated and measured integral gamma-ray absorbed doses using TLD, shows that calculation slightly overestimates the measurement with a C/E value equal to 1.05 {+-} 5.3 % (k = 2). By using OSLD, the calculation slightly underestimates the measurement with a C/E value equal to 0.96 {+-} 7.0% (k = 2. (authors)« less

  19. Assessment of Gamma-Ray Spectra Analysis Method Utilizing the Fireworks Algorithm for various Error Measures

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Alamaniotis, Miltiadis; Tsoukalas, Lefteri H.

    2018-01-01

    Significant role in enhancing nuclear nonproliferation plays the analysis of obtained data and the inference of the presence or not of special nuclear materials in them. Among various types of measurements, gamma-ray spectra is the widest used type of data utilized for analysis in nonproliferation. In this chapter, a method that employs the fireworks algorithm (FWA) for analyzing gamma-ray spectra aiming at detecting gamma signatures is presented. In particular FWA is utilized to fit a set of known signatures to a measured spectrum by optimizing an objective function, with non-zero coefficients expressing the detected signatures. FWA is tested on amore » set of experimentally obtained measurements and various objective functions -MSE, RMSE, Theil-2, MAE, MAPE, MAP- with results exhibiting its potential in providing high accuracy and high precision of detected signatures. Furthermore, FWA is benchmarked against genetic algorithms, and multiple linear regression with results exhibiting its superiority over the rest tested algorithms with respect to precision for MAE, MAPE and MAP measures.« less

  20. Measurement of 0.511-MeV gamma rays with a balloon-borne Ge/Li/ spectrometer

    NASA Technical Reports Server (NTRS)

    Ling, J. C.; Mahoney, W. A.; Willett, J. B.; Jacobson, A. S.

    1977-01-01

    A collimated high-resolution gamma ray spectrometer was flown on a balloon over Palestine, Texas, on June 10, 1974, to obtain measurements of the terrestrial and extraterrestrial 0.511-MeV gamma rays. The spectrometer consists of four 40-cu-cm Ge(Li) crystals operating in the energy range 0.06-10 MeV; this cluster of detectors is surrounded by a CsI(Na) anticoincidence shield. This system is used primarily to allow measurements of the two escape peaks associated with high-energy gamma ray lines. It also allows a measurement of the background component of the 0.511-MeV flux produced by beta(+) decays in materials inside the CsI(Na) shield. It is shown that the measurements of the atmospheric fluxes are consistent with earlier results after allowance is made for an additional component of the background due to beta(+) decays produced by neutron- and proton-initiated interactions with materials in and near the detector. Results of the extraterrestrial flux require an extensive detailed analysis of the time-varying background because of activation buildup and balloon spatial drifts.

  1. Low energy proton capture study of the 14N(p, gamma)15O reaction

    NASA Astrophysics Data System (ADS)

    Daigle, Stephen Michael

    The 14N(p,gamma)15O reaction regulates the rate of energy production for stars slightly more massive than the sun throughout stable hydrogen burning on the main sequence. The 14N(p,gamma)15O reaction rate also determines the luminosity for all stars after leaving the main sequence when their cores have exhausted hydrogen fuel, and later when they become red giant stars. The significant role that this reaction plays in stellar evolution has far-reaching consequences, from neutrino production in our Sun, to age estimates of globular clusters in our Galaxy. The weak cross section and inherent coincidence summing in the 15O gamma-ray decay scheme make a precision measurement of the astrophysical S-factor especially challenging, particularly for the ground-state transition. The present study, performed in the Laboratory for Experimental Nuclear Astrophysics (LENA), was aimed at measuring the ground-state transition at low energy by utilizing a new 24-element, position-sensitive, NaI(Tl) detector array. Because the array is highly segmented, the 14N( p,gamma)15O S-factor was evaluated for transitions to the ground, 5.18, 6.18, and 6.79 MeV states without the need for coincidence summing corrections. Additionally, the position-sensitivity of the detector was exploited to measure the angular correlation of the two-photon cascades. Software cuts were made to the data in order to identify single and coincident gamma-ray events and a fraction fit analysis technique was used to extract the characteristic 15O peaks from the composite gamma-ray spectrum. The results from the current work demonstrated a new approach to measuring weak nuclear cross sections near astrophysically relevant energies that, with refinements, has broader applications in gamma-ray spectroscopy.

  2. Gamma-Ray Imager With High Spatial And Spectral Resolution

    NASA Technical Reports Server (NTRS)

    Callas, John L.; Varnell, Larry S.; Wheaton, William A.; Mahoney, William A.

    1996-01-01

    Gamma-ray instrument developed to enable both two-dimensional imaging at relatively high spatial resolution and spectroscopy at fractional-photon-energy resolution of about 10 to the negative 3rd power in photon-energy range from 10 keV to greater than 10 MeV. In its spectroscopic aspect, instrument enables identification of both narrow and weak gamma-ray spectral peaks.

  3. Modeling the Martian neutron and gamma-ray leakage fluxes using Geant4

    NASA Astrophysics Data System (ADS)

    Pirard, Benoit; Desorgher, Laurent; Diez, Benedicte; Gasnault, Olivier

    A new evaluation of the Martian neutron and gamma-ray (continuum and line) leakage fluxes has been performed using the Geant4 code. Even if numerous studies have recently been carried out with Monte Carlo methods to characterize planetary radiation environments, only a few however have been able to reproduce in detail the neutron and gamma-ray spectra observed in orbit. We report on the efforts performed to adapt and validate the Geant4-based PLAN- ETOCOSMICS code for use in planetary neutron and gamma-ray spectroscopy data analysis. Beside the advantage of high transparency and modularity common to Geant4 applications, the new code uses reviewed nuclear cross section data, realistic atmospheric profiles and soil layering, as well as specific effects such as gravity acceleration for low energy neutrons. Results from first simulations are presented for some Martian reference compositions and show a high consistency with corresponding neutron and gamma-ray spectra measured on board Mars Odyssey. Finally we discuss the advantages and perspectives of the improved code for precise simulation of planetary radiation environments.

  4. Measurement and analysis of gamma-rays emitted from spent nuclear fuel above 3 MeV.

    PubMed

    Rodriguez, Douglas C; Anderson, Elaina; Anderson, Kevin K; Campbell, Luke W; Fast, James E; Jarman, Kenneth; Kulisek, Jonathan; Orton, Christopher R; Runkle, Robert C; Stave, Sean

    2013-12-01

    The gamma-ray spectrum of spent nuclear fuel in the 3-6 MeV energy range is important for active interrogation since gamma rays emitted from nuclear decay are not expected to interfere with measurements in this energy region. There is, unfortunately, a dearth of empirical measurements from spent nuclear fuel in this region. This work is an initial attempt to partially fill this gap by presenting an analysis of gamma-ray spectra collected from a set of spent nuclear fuel sources using a high-purity germanium detector array. This multi-crystal array possesses a large collection volume, providing high energy resolution up to 16 MeV. The results of these measurements establish the continuum count-rate in the energy region between 3 and 6 MeV. Also assessed is the potential for peaks from passive emissions to interfere with peak measurements resulting from active interrogation delayed emissions. As one of the first documented empirical measurements of passive emissions from spent fuel for energies above 3 MeV, this work provides a foundation for active interrogation model validation and detector development. © 2013 Elsevier Ltd. All rights reserved.

  5. [Study on physical deviation factors on laser induced breakdown spectroscopy measurement].

    PubMed

    Wan, Xiong; Wang, Peng; Wang, Qi; Zhang, Qing; Zhang, Zhi-Min; Zhang, Hua-Ming

    2013-10-01

    In order to eliminate the deviation between the measured LIBS spectral line and the standard LIBS spectral line, and improve the accuracy of elements measurement, a research of physical deviation factors in laser induced breakdown spectroscopy technology was proposed. Under the same experimental conditions, the relationship of ablated hole effect and spectral wavelength was tested, the Stark broadening data of Mg plasma laser induced breakdown spectroscopy with sampling time-delay from 1.00 to 3.00 micros was also studied, thus the physical deviation influences such as ablated hole effect and Stark broadening could be obtained while collecting the spectrum. The results and the method of the research and analysis can also be applied to other laser induced breakdown spectroscopy experiment system, which is of great significance to improve the accuracy of LIBS elements measuring and is also important to the research on the optimum sampling time-delay of LIBS.

  6. Optical gamma thermometer

    DOEpatents

    Koster, Glen Peter; Xia, Hua; Lee, Boon Kwee

    2013-08-06

    An optical gamma thermometer includes a metal mass having a temperature proportional to a gamma flux within a core of a nuclear reactor, and an optical fiber cable for measuring the temperature of the heated metal mass. The temperature of the heated mass may be measured by using one or more fiber grating structures and/or by using scattering techniques, such as Raman, Brillouin, and the like. The optical gamma thermometer may be used in conjunction with a conventional reactor heat balance to calibrate the local power range monitors over their useful in-service life. The optical gamma thermometer occupies much less space within the in-core instrument tube and costs much less than the conventional gamma thermometer.

  7. A Modular Pipelined Processor for High Resolution Gamma-Ray Spectroscopy

    NASA Astrophysics Data System (ADS)

    Veiga, Alejandro; Grunfeld, Christian

    2016-02-01

    The design of a digital signal processor for gamma-ray applications is presented in which a single ADC input can simultaneously provide temporal and energy characterization of gamma radiation for a wide range of applications. Applying pipelining techniques, the processor is able to manage and synchronize very large volumes of streamed real-time data. Its modular user interface provides a flexible environment for experimental design. The processor can fit in a medium-sized FPGA device operating at ADC sampling frequency, providing an efficient solution for multi-channel applications. Two experiments are presented in order to characterize its temporal and energy resolution.

  8. Line Narrowing Parameter Measurement by Modulation Spectroscopy

    NASA Technical Reports Server (NTRS)

    Dharamsi, Amin N.

    1998-01-01

    Accurate Characterization of Oxygen A-Band Line Parameters by Wavelength Modulation Spectroscopy with tunable diode lasers is an ongoing research at Old Dominion University, under sponsorship from NASA Langley research Center. The work proposed here will be undertaken under the guidance of Dr. William Chu and Dr. Lamont Poole of the Aerosol Research Branch at NASA Langley-Research Center in Hampton, Virginia. The research was started about two years ago and utilizes wavelength modulation absorption spectroscopy with higher harmonic detection, a technique that we developed at Old Dominion University, to obtain the absorption line characteristics of the Oxygen A-band rovibronic lines. Accurate characterization of this absorption band is needed for processing of data that will be obtained in experiments such as the NASA Stratospheric Aerosol and Gas Experiment III (SAGE III) as part of the US Mission to Planet Earth. The research work for Summer Fellowship undertook a measurement of the Dicke line-narrowing parameters of the Oxygen A-Band lines by using wavelength modulation spectroscopy. Our previous theoretical results had indicated that such a measurement could be done sensitively and in a convenient fashion by using this type of spectroscopy. In particular, theoretical results had indicated that the signal magnitude would depend on pressure in a manner that was very sensitive to the narrowing parameter. One of the major tasks undertaken during the summer of 1998 was to establish experimentally that these theoretical predictions were correct. This was done successfully and the results of the work are being prepared for publication. Experimental Results were obtained in which the magnitude of the signal was measured as a function of pressure, for various harmonic detection orders (N = 1, 2, 3, 4, 5). A comparison with theoretical results was made, and it was shown that the agreement between theory and experiment was very good. More importantly, however, it was shown

  9. Design and Performance of the GAMMA-400 Gamma-Ray Telescope for Dark Matter Searches

    NASA Technical Reports Server (NTRS)

    Galper, A.M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A.I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu. V.; hide

    2012-01-01

    The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma-rays and cosmic-ray electrons + positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma-rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is approx. 0.01 deg (E(sub gamma) > 100 GeV), the energy resolution approx. 1% (E(sub gamma) > 10 GeV), and the proton rejection factor approx 10(exp 6). GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

  10. Comparison of electrical capacitance tomography & gamma densitometer measurement in viscous oil-gas flows

    NASA Astrophysics Data System (ADS)

    Archibong Eso, A.; Zhao, Yabin; Yeung, Hoi

    2014-04-01

    Multiphase flow is a common occurrence in industries such as nuclear, process, oil & gas, food and chemical. A prior knowledge of its features and characteristics is essential in the design, control and management of such processes due to its complex nature. Electrical Capacitance Tomography (ECT) and Gamma Densitometer (Gamma) are two promising approaches for multiphase visualization and characterization in process industries. In two phase oil & gas flow, ECT and Gamma are used in multiphase flow monitoring techniques due to their inherent simplicity, robustness, and an ability to withstand wide range of operational temperatures and pressures. High viscous oil (viscosity > 100 cP) is of interest because of its huge reserves, technological advances in its production and unlike conventional oil (oil viscosity < 100 cP) and gas flows where ECT and Gamma have been previously used, high viscous oil and gas flows comes with certain associated concerns which include; increased entrainment of gas bubbles dispersed in oil, shorter and more frequent slugs as well as oil film coatings on the walls of flowing conduits. This study aims to determine the suitability of both devices in the visualization and characterization of high-viscous oil and gas flow. Static tests are performed with both devices and liquid holdup measurements are obtained. Dynamic experiments were also conducted in a 1 & 3 inch facility at Cranfield University with a range of nominal viscosities (1000, 3000 & 7500 cP). Plug, slug and wavy annular flow patterns were identified by means of Probability Mass Function and time series analysis of the data acquired from Gamma and ECT devices with high speed camera used to validate the results. Measured Liquid holdups for both devices were also compared.

  11. Pulsed laser diffusion of thin hole-barrier contacts in high purity germanium for gamma radiation detectors

    NASA Astrophysics Data System (ADS)

    Maggioni, G.; Carturan, S.; Raniero, W.; Riccetto, S.; Sgarbossa, F.; Boldrini, V.; Milazzo, R.; Napoli, D. R.; Scarpa, D.; Andrighetto, A.; Napolitani, E.; De Salvador, D.

    2018-03-01

    A new method for the formation of hole-barrier contacts in high purity germanium (HPGe) is described, which consists in the sputter deposition of a Sb film on HPGe, followed by Sb diffusion produced through laser annealing of the Ge surface in the melting regime. This process gives rise to a very thin ( ≤ 100 nm) n-doped layer, as determined by SIMS measurement, while preserving the defect-free morphology of HPGe surface. A small prototype of gamma ray detector with a Sb laser-diffused contact was produced and characterized, showing low leakage currents and good spectroscopy data with different gamma ray sources.

  12. Effects of gamma irradiations on reactive pulsed laser deposited vanadium dioxide thin films

    NASA Astrophysics Data System (ADS)

    Madiba, I. G.; Émond, N.; Chaker, M.; Thema, F. T.; Tadadjeu, S. I.; Muller, U.; Zolliker, P.; Braun, A.; Kotsedi, L.; Maaza, M.

    2017-07-01

    Vanadium oxide films are considered suitable coatings for various applications such as thermal protective coating of small spacecrafts because of their thermochromic properties. While in outer space, such coating will be exposed to cosmic radiations which include γ-rays. To study the effect of these γ-rays on the coating properties, we have deposited vanadium dioxide (VO2) films on silicon substrates and subjected them to extensive γ-irradiations with typical doses encountered in space missions. The prevalent crystallographic phase after irradiation remains the monoclinic VO2 phase but the films preferential orientation shifts to lower angles due to the presence of disordered regions caused by radiations. Raman spectroscopy measurements also evidences that the VO2 structure is slightly affected by gamma irradiation. Indeed, increasing the gamma rays dose locally alters the crystalline and electronic structures of the films by modifying the V-V inter-dimer distance, which in turns favours the presence of the VO2 metallic phase. From the XPS measurements of V2p and O1s core level spectra, an oxidation of vanadium from V4+ towards V5+ is revealed. The data also reveal a hydroxylation upon irradiation which is corroborated by the vanishing of a low oxidation state peak near the Fermi energy in the valence band. Our observations suggest that gamma radiations induce the formation of Frenkel pairs. Moreover, THz transmission measurements show that the long range structure of VO2 remains intact after irradiation whilst the electrical measurements evidence that the coating resistivity decreases with gamma irradiation and that their transition temperature is slightly reduced for high gamma ray doses. Even though gamma rays are only one of the sources of radiations that are encountered in space environment, these results are very promising with regards to the potential of integration of such VO2 films as a protective coating for spacecrafts.

  13. High resolution gamma-ray spectrometry of culverts containing transuranic waste at the Savannah River Site

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hofstetter, K.J.; Sigg, R.

    1990-12-31

    A number of concrete culverts used to retrievably store drummed, dry, radioactive waste at the Savannah River Site (SRS), were suspected of containing ambiguous quantities of transuranic (TRU) nuclides. These culverts were assayed in place for Pu-239 content using thermal and fast neutron counting techniques. High resolution gamma-ray spectroscopy on 17 culverts, having neutron emission rates several times higher than expected, showed characteristic gamma-ray signatures of neutron emitters other than Pu-239 (e.g., Pu-238, Pu/Be, or Am/Be neutron sources). This study confirmed the Pu-239 content of the culverts with anomalous neutron rates and established limits on the Pu-239 mass in eachmore » of the 17 suspect culverts by in-field, non-intrusive gamma-ray measurements.« less

  14. High resolution gamma-ray spectrometry of culverts containing transuranic waste at the Savannah River Site

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hofstetter, K.J.; Sigg, R.

    1990-01-01

    A number of concrete culverts used to retrievably store drummed, dry, radioactive waste at the Savannah River Site (SRS), were suspected of containing ambiguous quantities of transuranic (TRU) nuclides. These culverts were assayed in place for Pu-239 content using thermal and fast neutron counting techniques. High resolution gamma-ray spectroscopy on 17 culverts, having neutron emission rates several times higher than expected, showed characteristic gamma-ray signatures of neutron emitters other than Pu-239 (e.g., Pu-238, Pu/Be, or Am/Be neutron sources). This study confirmed the Pu-239 content of the culverts with anomalous neutron rates and established limits on the Pu-239 mass in eachmore » of the 17 suspect culverts by in-field, non-intrusive gamma-ray measurements.« less

  15. Lactoferrin-Immobilized Surfaces onto Functionalized PLA Assisted by the Gamma-Rays and Nitrogen Plasma to Create Materials with Multifunctional Properties.

    PubMed

    Stoleru, Elena; Zaharescu, Traian; Hitruc, Elena Gabriela; Vesel, Alenka; Ioanid, Emil G; Coroaba, Adina; Safrany, Agnes; Pricope, Gina; Lungu, Maria; Schick, Christoph; Vasile, Cornelia

    2016-11-23

    Both cold nitrogen radiofrequency plasma and gamma irradiation have been applied to activate and functionalize the polylactic acid (PLA) surface and the subsequent lactoferrin immobilization. Modified films were comparatively characterized with respect to the procedure of activation and also with unmodified sample by water contact angle measurements, mass loss, X-ray photoelectron spectroscopy (XPS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), and chemiluminescence measurements. All modified samples exhibit enhanced surface properties mainly those concerning biocompatibility, antimicrobial, and antioxidant properties, and furthermore, they are biodegradable and environmentally friendly. Lactoferrin deposited layer by covalent coupling using carbodiimide chemistry showed a good stability. It was found that the lactoferrin-modified PLA materials present significantly increased oxidative stability. Gamma-irradiated samples and lactoferrin-functionalized samples show higher antioxidant, antimicrobial, and cell proliferation activity than plasma-activated and lactoferrin-functionalized ones. The multifunctional materials thus obtained could find application as biomaterials or as bioactive packaging films.

  16. Gamma ray astrophysics to the year 2000. Report of the NASA Gamma Ray Program Working Group

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Important developments in gamma-ray astrophysics up to energies of 100 GeV during the last decade are reviewed. Also, the report seeks to define the major current scientific goals of the field and proposes a vigorous program to pursue them, extending to the year 2000. The goals of gamma-ray astronomy include the study of gamma rays which provide the most direct means of studying many important problems in high energy astrophysics including explosive nucleosynthesis, accelerated particle interactions and sources, and high-energy processes around compact objects. The current research program in gamma-ray astronomy in the U.S. including the space program, balloon program and foreign programs in gamma-ray astronomy is described. The high priority recommendations for future study include an Explorer-class high resolution gamma-ray spectroscopy mission and a Get Away Special cannister (GAS-can) or Scout class multiwavelength experiment for the study of gamma-ray bursts. Continuing programs include an extended Gamma Ray Observatory mission, continuation of the vigorous program of balloon observations of the nearby Supernova 1987A, augmentation of the balloon program to provide for new instruments and rapid scientific results, and continuation of support for theoretical research. Long term recommendations include new space missions using advanced detectors to better study gamma-ray sources, the development of these detectors, continued study for the assembly of large detectors in space, collaboration with the gamma-ray astronomy missions initiated by other countries, and consideration of the Space Station attached payloads for gamma-ray experiments.

  17. TRANSISTORIZED RADIATION MEASURING APPARATUS FOR $gamma$-RAYS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Beug, L.; Rudack, G.

    1961-06-24

    It is often necessary to measure the content of containers which for various reasons cannot be opened or inspected visually, but the gamma rays emitted by certain radioisotopes can be used for these measuring purposes because they can penetrate iron walls of from 2 to 100 mm thickness. A level gage is described which consists of a measuring table, a radiation source, a radiation detector, a transformer which converts the incident rays in electric current, a discriminator, a recording device, and an adequate current supply. In principle, there are 2 different measuring methods: one uses 2 counting tubes and determinesmore » the level by the difference method, while the other uses only one tube which has been calibrated with a standard source. Several circuit diagrams used in the construction of the devices are discussed. The use of transistors instead of electron tubes is advantageous because they are more compact, sturdier, less dependent on temperature, have a longer life time, and are more economical. A table shows the characteristic properties of one radiation measuring device: 100 pulses/sec, 200 mu amp, -20 deg -+50 deg C, 500-5000 OMEGA , 12w, counting duration 10/sup 10/ pulses. (OID)« less

  18. Test results of a new detector system for gamma ray isotopic measurements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Malcom, J.E.; Bonner, C.A.; Hurd, J.R.

    1993-08-01

    A new type of gamma-ray detector system for isotopic measurements has been developed. This new system, a ``Duo detector`` array, consists of two intrinsic germanium detectors, a planar followed by a coaxial mounted on the same axis within a single cryostat assembly. This configuration allows the isotopic analysis system to take advantage of spectral data results that are collected simultaneously from different gamma-ray energy regimes. Princeton Gamma Tech (PGT) produced several prototypes of this Duo detector array which were then tested by Rocky Flats personnel until the design was optimized. An application for this detector design is in automated, roboticizedmore » NDA systems such as those being developed at the Los Alamos TA-55 Plutonium Facility. The Duo detector design reduces the space necessary for the isotopic instrument by a factor of two (only one liquid nitrogen dewar is needed), and also reduces the complexity of the mechanical systems and controlling software. Data will be presented on measurements of nuclear material with a Duo detector for a wide variety of matrices. Results indicate that the maximum count rate can be increased up to 100,000 counts per second yet maintaining excellent resolution and energy rate product.« less

  19. Design and Performance of the GAMMA-400 Gamma-Ray Telescope for Dark Matter Searches

    NASA Technical Reports Server (NTRS)

    Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu V.; hide

    2012-01-01

    The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma-rays and cosmic-ray electrons (+) positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma-rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is approximately 0.01deg (E(sub gamma) greater than 100 GeV), the energy resolution approximately 1% (E(sub gamma) greater than 10 GeV), and the proton rejection factor approximately 10(exp 6). GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

  20. Gamma-ray spectroscopy: The diffuse galactic glow

    NASA Technical Reports Server (NTRS)

    Hartmann, Dieter H.

    1991-01-01

    The goal of this project is the development of a numerical code that provides statistical models of the sky distribution of gamma-ray lines due to the production of radioactive isotopes by ongoing Galactic nucleosynthesis. We are particularly interested in quasi-steady emission from novae, supernovae, and stellar winds, but continuum radiation and transient sources must also be considered. We have made significant progress during the first half period of this project and expect the timely completion of a code that can be applied to Oriented Scintillation Spectrometer Experiment (OSSE) Galactic plane survey data.

  1. Measuring Gravitation Using Polarization Spectroscopy

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey; Yu, Nan; Maleki, Lute

    2004-01-01

    A proposed method of measuring gravitational acceleration would involve the application of polarization spectroscopy to an ultracold, vertically moving cloud of atoms (an atomic fountain). A related proposed method involving measurements of absorption of light pulses like those used in conventional atomic interferometry would yield an estimate of the number of atoms participating in the interferometric interaction. The basis of the first-mentioned proposed method is that the rotation of polarization of light is affected by the acceleration of atoms along the path of propagation of the light. The rotation of polarization is associated with a phase shift: When an atom moving in a laboratory reference interacts with an electromagnetic wave, the energy levels of the atom are Doppler-shifted, relative to where they would be if the atom were stationary. The Doppler shift gives rise to changes in the detuning of the light from the corresponding atomic transitions. This detuning, in turn, causes the electromagnetic wave to undergo a phase shift that can be measured by conventional means. One would infer the gravitational acceleration and/or the gradient of the gravitational acceleration from the phase measurements.

  2. A New Optical Design for Imaging Spectroscopy

    NASA Astrophysics Data System (ADS)

    Thompson, K. L.

    2002-05-01

    We present an optical design concept for imaging spectroscopy, with some advantages over current systems. The system projects monochromatic images onto the 2-D array detector(s). Faint object and crowded field spectroscopy can be reduced first using image processing techniques, then building the spectrum, unlike integral field units where one must first extract the spectra, build data cubes from these, then reconstruct the target's integrated spectral flux. Like integral field units, all photons are detected simultaneously, unlike tunable filters which must be scanned through the wavelength range of interest and therefore pay a sensitivity pentalty. Several sample designs are presented, including an instrument optimized for measuring intermediate redshift galaxy cluster velocity dispersions, one designed for near-infrared ground-based adaptive optics, and one intended for space-based rapid follow-up of transient point sources such as supernovae and gamma ray bursts.

  3. Design and performance of the GAMMA-400 gamma-ray telescope for dark matter searches

    NASA Astrophysics Data System (ADS)

    Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu. V.; Kaplin, V. A.; Kachanov, V. A.; Kheymits, M. D.; Leonov, A. A.; Longo, F.; Mazets, E. P.; Maestro, P.; Marrocchesi, P.; Mereminskiy, I. A.; Mikhailov, V. V.; Moiseev, A. A.; Mocchiutti, E.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu.; Papini, P.; Picozza, P.; Rodin, V. G.; Runtso, M. F.; Sparvoli, R.; Spillantini, P.; Suchkov, S. I.; Tavani, M.; Topchiev, N. P.; Vacchi, A.; Vannuccini, E.; Yurkin, Yu. T.; Zampa, N.; Zverev, V. G.; Zirakashvili, V. N.

    2013-02-01

    The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma-rays and cosmic-ray electrons + positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma-rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is ~0.01° (Eγ > 100 GeV), the energy resolution ~1% (Eγ > 10 GeV), and the proton rejection factor ~106. GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

  4. An industrial radiography exposure device based on measurement of transmitted gamma-ray intensity

    NASA Astrophysics Data System (ADS)

    Polee, C.; Chankow, N.; Srisatit, S.; Thong-Aram, D.

    2015-05-01

    In film radiography, underexposure and overexposure may happen particularly when lacking information of specimen material and hollowness. This paper describes a method and a device for determining exposure in industrial gamma-ray radiography based on quick measurement of transmitted gamma-ray intensity with a small detector. Application software was developed for Android mobile phone to remotely control the device and to display counting data via Bluetooth communication. Prior to film exposure, the device is placed behind a specimen to measure transmitted intensity which is inversely proportional to the exposure. Unlike in using the conventional exposure curve, correction factors for source decay, source-to- film distance, specimen thickness and kind of material are not needed. The developed technique and device make radiographic process economic, convenient and more reliable.

  5. High Resolution Gamma Ray Spectroscopy at MHz Counting Rates With LaBr3 Scintillators for Fusion Plasma Applications

    NASA Astrophysics Data System (ADS)

    Nocente, M.; Tardocchi, M.; Olariu, A.; Olariu, S.; Pereira, R. C.; Chugunov, I. N.; Fernandes, A.; Gin, D. B.; Grosso, G.; Kiptily, V. G.; Neto, A.; Shevelev, A. E.; Silva, M.; Sousa, J.; Gorini, G.

    2013-04-01

    High resolution γ-ray spectroscopy measurements at MHz counting rates were carried out at nuclear accelerators, combining a LaBr 3(Ce) detector with dedicated hardware and software solutions based on digitization and off-line analysis. Spectra were measured at counting rates up to 4 MHz, with little or no degradation of the energy resolution, adopting a pile up rejection algorithm. The reported results represent a step forward towards the final goal of high resolution γ-ray spectroscopy measurements on a burning plasma device.

  6. 7T Proton Magnetic Resonance Spectroscopy of Gamma-Aminobutyric Acid, Glutamate, and Glutamine Reveals Altered Concentrations in Patients With Schizophrenia and Healthy Siblings.

    PubMed

    Thakkar, Katharine N; Rösler, Lara; Wijnen, Jannie P; Boer, Vincent O; Klomp, Dennis W J; Cahn, Wiepke; Kahn, René S; Neggers, Sebastiaan F W

    2017-03-15

    The N-methyl-D-aspartate receptor hypofunction model of schizophrenia predicts dysfunction in both glutamatergic and gamma-aminobutyric acidergic (GABAergic) transmission. We addressed this hypothesis by measuring GABA, glutamate, glutamine, and the sum of glutamine plus glutamate concentrations in vivo in patients with schizophrenia using proton magnetic resonance spectroscopy at 7T, which allows separation of metabolites that would otherwise overlap at lower field strengths. In addition, we investigated whether altered levels of GABA, glutamate, glutamine, and the sum of glutamine plus glutamate reflect genetic vulnerability to schizophrenia by including healthy first-degree relatives. Proton magnetic resonance spectroscopy at 7T was performed in 21 patients with chronic schizophrenia who were taking medication, 23 healthy first-degree relatives of patients with schizophrenia, and 24 healthy nonrelatives. Glutamate, glutamine, and GABA were measured cortically and subcortically in bilateral basal ganglia and occipital cortex. Patients with schizophrenia had reduced cortical GABA compared with healthy relatives and the combined sample of healthy relatives and healthy nonrelatives, suggesting that altered GABAergic systems in schizophrenia are associated with either disease state or medication effects. Reduced cortical glutamine relative to healthy control subjects was observed in patients with schizophrenia and the combined sample of healthy relatives and patients with schizophrenia, suggesting that altered glutamatergic metabolite levels are associated with illness liability. No group differences were found in the basal ganglia. Taken together, these findings are consistent with alterations in GABAergic and glutamatergic systems in patients with schizophrenia and provide novel insights into these systems in healthy relatives. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  7. Gamma-ray luminosity and photon index evolution of FSRQ blazars and contribution to the gamma-ray background

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Singal, J.; Ko, A.; Petrosian, V., E-mail: jsingal@richmond.edu

    We present the redshift evolutions and distributions of the gamma-ray luminosity and photon spectral index of flat spectrum radio quasar (FSRQ) type blazars, using non-parametric methods to obtain the evolutions and distributions directly from the data. The sample we use for analysis consists of almost all FSRQs observed with a greater than approximately 7σ detection threshold in the first-year catalog of the Fermi Gamma-ray Space Telescope's Large Area Telescope, with redshifts as determined from optical spectroscopy by Shaw et al. We find that FSQRs undergo rapid gamma-ray luminosity evolution, but negligible photon index evolution, with redshift. With these evolutions accountedmore » for we determine the density evolution and luminosity function of FSRQs and calculate their total contribution to the extragalactic gamma-ray background radiation, resolved and unresolved, which is found to be 16(+10/–4)%, in agreement with previous studies.« less

  8. Increase in neutrophil Fc gamma receptor I expression following interferon gamma treatment in rheumatoid arthritis.

    PubMed Central

    Goulding, N J; Knight, S M; Godolphin, J L; Guyre, P M

    1992-01-01

    The therapeutic potential of interferon gamma (IFN gamma) in a number of disease states is still being explored, but progress is hampered by the lack of a suitable measure of in vivo biological activity. To assess the in vivo biological effects of recombinant human IFN gamma (rhIFN gamma), 14 patients were studied in a randomised, prospective, double blind, placebo controlled trial of this cytokine for the treatment of rheumatoid arthritis. The levels of Fc gamma receptors on peripheral blood neutrophils were measured at baseline and after 21 days of once daily, subcutaneous injections of rhIFN gamma or placebo. An induction of neutrophil Fc gamma receptor type I (Fc gamma RI) was seen in the group of patients receiving recombinant human rhIFN gamma but not in those receiving placebo. No change in the expression of Fc gamma RII or Fc gamma RIII was detected. The amount of induction of Fc gamma RI detected on the neutrophils of patients receiving rhIFN gamma did not correlate with clinical measures of response at either 21 days or at the end of the study (24 weeks). No significant clinical responses were observed in the rhIFN gamma group at these times. These data confirm that the reported in vitro effect of IFN gamma on human neutrophil Fc receptor expression can be reproduced in vivo. PMID:1534001

  9. Increase in neutrophil Fc gamma receptor I expression following interferon gamma treatment in rheumatoid arthritis.

    PubMed

    Goulding, N J; Knight, S M; Godolphin, J L; Guyre, P M

    1992-04-01

    The therapeutic potential of interferon gamma (IFN gamma) in a number of disease states is still being explored, but progress is hampered by the lack of a suitable measure of in vivo biological activity. To assess the in vivo biological effects of recombinant human IFN gamma (rhIFN gamma), 14 patients were studied in a randomised, prospective, double blind, placebo controlled trial of this cytokine for the treatment of rheumatoid arthritis. The levels of Fc gamma receptors on peripheral blood neutrophils were measured at baseline and after 21 days of once daily, subcutaneous injections of rhIFN gamma or placebo. An induction of neutrophil Fc gamma receptor type I (Fc gamma RI) was seen in the group of patients receiving recombinant human rhIFN gamma but not in those receiving placebo. No change in the expression of Fc gamma RII or Fc gamma RIII was detected. The amount of induction of Fc gamma RI detected on the neutrophils of patients receiving rhIFN gamma did not correlate with clinical measures of response at either 21 days or at the end of the study (24 weeks). No significant clinical responses were observed in the rhIFN gamma group at these times. These data confirm that the reported in vitro effect of IFN gamma on human neutrophil Fc receptor expression can be reproduced in vivo.

  10. OPTIMIZATION OF VIRTUAL FRISCH-GRID CdZnTe DETECTOR DESIGNS FOR IMAGING AND SPECTROSCOPY OF GAMMA RAYS.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    BOLOTNIKOV,A.E.; ABDUL-JABBAR, N.M.; BABALOLA, S.

    2007-08-21

    In the past, various virtual Frisch-grid designs have been proposed for cadmium zinc telluride (CZT) and other compound semiconductor detectors. These include three-terminal, semi-spherical, CAPture, Frisch-ring, capacitive Frisch-grid and pixel devices (along with their modifications). Among them, the Frisch-grid design employing a non-contacting ring extended over the entire side surfaces of parallelepiped-shaped CZT crystals is the most promising. The defect-free parallelepiped-shaped crystals with typical dimensions of 5x5{approx}12 mm3 are easy to produce and can be arranged into large arrays used for imaging and gamma-ray spectroscopy. In this paper, we report on further advances of the virtual Frisch-grid detector design formore » the parallelepiped-shaped CZT crystals. Both the experimental testing and modeling results are described.« less

  11. Measurements of the gamma-quanta angular distributions emitted from neutron inelastic scattering on 28Si

    NASA Astrophysics Data System (ADS)

    Fedorov, N. A.; Grozdanov, D. N.; Bystritskiy, V. M.; Kopach, Yu. N.; Ruskov, I. N.; Skoy, V. R.; Tretyakova, T. Yu.; Zamyatin, N. I.; Wang, D.; Aliev, F. A.; Hramco, C.; Gandhi, A.; Kumar, A.; Dabylova, S.; Bogolubov, E. P.; Barmakov, Yu. N.

    2018-04-01

    The characteristic gamma radiation from the interaction of 14.1 MeV neutrons with a natural silicon sample is investigated with Tagged Neutron Method (TNM). The anisotropy of gamma-ray emission of 1.779 MeV was measured at 11 azimuth angles with a step of ∠15°. The present results are in good agreement with some recent experimental data.

  12. Investigation of radiosterilization feasibility of sulfamethoxazole by ESR spectroscopy

    NASA Astrophysics Data System (ADS)

    Çolak, Şeyda

    2017-12-01

    In the present study, the spectroscopic features of the radiolytic intermediates that were produced in gamma-irradiated (5, 10, 25 and 50 kGy) sulfamethoxazole (SMX) have been investigated by electron spin resonance (ESR) spectroscopy and the radiation sterilization feasibility of SMX by ionizing radiation was examined. Gamma-irradiated SMX exhibited a complex ESR spectrum consisting of 13 resonance lines where spectral parameters for the central resonance line were found to be g = 2.0062 and ΔHpp = 0.6 mT. The radiation yield of SMX was calculated to be relatively low (G = 0.1) by ESR spectroscopy and no meaningful difference was observed in the comparison of unirradiated and 50 kGy gamma irradiated SMX by the Fourier transform infrared (FT-IR) technique, confirming that SMX is a radioresistive material. Although SMX could not be accepted to be a good dosimetric material, the identification of irradiated SMX from the unirradiated sample was possible even for the low absorbed radiation doses and for a relatively long time (three months) after the irradiation process. Decay activation energy of the radical species, which is mostly responsible for the central intense resonance line, is calculated to be 45.15 kJ/mol by using the signal intensity decay data derived from annealing studies. Four radical species with different spectroscopic properties were accepted to be responsible for the ESR spectra of gamma-irradiated SMX, by simulation calculations. It is concluded that SMX and SMX-containing drugs can be sterilized by gamma radiation and ESR spectroscopy is an appropriate technique for the characterization of these induced radical intermediates during the gamma irradiation process of SMX. Toxicology tests should also be done for its safe usage.

  13. Integral measurements of neutron and gamma-ray leakage fluxes from the Little Boy replica

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Muckenthaler, F.J.

    This report presents integral measurements of neutron and gamma-ray leakage fluxes from a critical mockup of the Hiroshima bomb Little Boy at Los Alamos National Laobratory with detector systems developed by Oak Ridge National Laboratory. Bonner ball detectors were used to map the neutron fluxes in the horizontal midplane at various distances from the mockup and for selected polar angles, keeping the source-detector separation constant. Gamma-ray energy deposition measurements were made with thermoluminescent detectors at several locations on the iron shell of the source mockup. The measurements were performed as part of a larger progam to provide benchmark data formore » testing the methods used to calculate the radiation released from the Little Boy bomb over Hiroshima. 3 references, 10 figures.« less

  14. Design of high-linear CMOS circuit using a constant transconductance method for gamma-ray spectroscopy system

    NASA Astrophysics Data System (ADS)

    Jung, I. I.; Lee, J. H.; Lee, C. S.; Choi, Y.-W.

    2011-02-01

    We propose a novel circuit to be applied to the front-end integrated circuits of gamma-ray spectroscopy systems. Our circuit is designed as a type of current conveyor (ICON) employing a constant- gm (transconductance) method which can significantly improve the linearity in the amplified signals by using a large time constant and the time-invariant characteristics of an amplifier. The constant- gm method is obtained by a feedback control which keeps the transconductance of the input transistor constant. To verify the performance of the propose circuit, the time constant variations for the channel resistances are simulated with the TSMC 0.18 μm transistor parameters using HSPICE, and then compared with those of a conventional ICON. As a result, the proposed ICON shows only 0.02% output linearity variation and 0.19% time constant variation for the input amplitude up to 100 mV. These are significantly small values compared to a conventional ICON's 1.39% and 19.43%, respectively, for the same conditions.

  15. Solubility Enhancement of Steviol Glycosides and Characterization of Their Inclusion Complexes with Gamma-Cyclodextrin

    PubMed Central

    Upreti, Mani; Strassburger, Ken; Chen, You L.; Wu, Shaoxiong; Prakash, Indra

    2011-01-01

    Steviol glycosidesrebaudioside (reb) A, C and D have low aqueous solubilities. To improve their aqueous solubilities, inclusion complex of steviol glycosides, reb A, C and D and gamma cyclodextrin were prepared by freeze drying method and further characterized by means of differential scanning calorimetry, Fourier transform infrared spectroscopy and Raman spectroscopy. The effect of gamma cyclodextrin on chemical shifts of the steviol glycosides was also studied in proton NMR experiments as well as in solid state 13C CP/MAS NMR experiments. These results indicated that the steviol glycosides were clearly in inclusion complex formation with the gamma cyclodextrin which also results in solubility enhancement of these steviol glycosides. Phase solubility studies showed that amounts of soluble reb A, C and D increased with increasing amounts of gamma cyclodextrin indicating formation of 1:1 stoichiometric and higher order inclusion complexes. PMID:22174615

  16. Anisotropies in the diffuse gamma-ray background measured by the Fermi LAT

    DOE PAGES

    Ackermann, M.; Ajello, M.; Albert, A.; ...

    2012-04-23

    The contribution of unresolved sources to the diffuse gamma-ray background could induce anisotropies in this emission on small angular scales. Here, we analyze the angular power spectrum of the diffuse emission measured by the Fermi Large Area Telescope at Galactic latitudes | b | > 30 ° in four energy bins spanning 1–50 GeV. At multipoles ℓ ≥ 155 , corresponding to angular scales ≲ 2 ° , angular power above the photon noise level is detected at > 99.99 % confidence level in the 1–2 GeV, 2–5 GeV, and 5–10 GeV energy bins, and at > 99 % confidencemore » level at 10–50 GeV. Within each energy bin the measured angular power takes approximately the same value at all multipoles ℓ ≥ 155 , suggesting that it originates from the contribution of one or more unclustered source populations. Furthermore, the amplitude of the angular power normalized to the mean intensity in each energy bin is consistent with a constant value at all energies, C P / < I > 2 = 9.05 ± 0.84 × 10 - 6 sr , while the energy dependence of C P is consistent with the anisotropy arising from one or more source populations with power-law photon spectra with spectral index Γ s = 2.40 ± 0.07 . We also discuss the implications of the measured angular power for gamma-ray source populations that may provide a contribution to the diffuse gamma-ray background.« less

  17. Differential sensitivity of Chironomus and human hemoglobin to gamma radiation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gaikwad, Pallavi S.; Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085; Panicker, Lata

    Chironomus ramosus is known to tolerate high doses of gamma radiation exposure. Larvae of this insect possess more than 95% of hemoglobin (Hb) in its circulatory hemolymph. This is a comparative study to see effect of gamma radiation on Hb of Chironomus and humans, two evolutionarily diverse organisms one having extracellular and the other intracellular Hb respectively. Stability and integrity of Chironomus and human Hb to gamma radiation was compared using biophysical techniques like Dynamic Light Scattering (DLS), UV-visible spectroscopy, fluorescence spectrometry and CD spectroscopy after exposure of whole larvae, larval hemolymph, human peripheral blood, purified Chironomus and human Hb.more » Sequence- and structure-based bioinformatics methods were used to analyze the sequence and structural similarities or differences in the heme pockets of respective Hbs. Resistivity of Chironomus Hb to gamma radiation is remarkably higher than human Hb. Human Hb exhibited loss of heme iron at a relatively low dose of gamma radiation exposure as compared to Chironomus Hb. Unlike human Hb, the heme pocket of Chironomus Hb is rich in aromatic amino acids. Higher hydophobicity around heme pocket confers stability of Chironomus Hb compared to human Hb. Previously reported gamma radiation tolerance of Chironomus can be largely attributed to its evolutionarily ancient form of extracellular Hb as evident from the present study. -- Highlights: •Comparison of radiation tolerant Chironomus Hb and radiation sensitive Human Hb. •Amino acid composition of midge and human heme confer differential hydrophobicity. •Heme pocket of evolutionarily ancient midge Hb provide gamma radiation resistivity.« less

  18. Predicting diffusion paths and interface motion in gamma/gamma + beta, Ni-Cr-Al diffusion couples

    NASA Technical Reports Server (NTRS)

    Nesbitt, J. A.; Heckel, R. W.

    1987-01-01

    A simplified model has been developed to predict Beta recession and diffusion paths in ternary gamma/gamma + beta diffusion couples (gamma:fcc, beta: NiAl structure). The model was tested by predicting beta recession and diffusion paths for four gamma/gamma + beta, Ni-Cr-Al couples annealed for 100 hours at 1200 C. The model predicted beta recession within 20 percent of that measured for each of the couples. The model also predicted shifts in the concentration of the gamma phase at the gamma/gamma + beta interface within 2 at. pct Al and 6 at. pct Cr of that measured in each of the couples. A qualitative explanation based on simple kinetic and mass balance arguments has been given which demonstrates the necessity for diffusion in the two-phase region of certain gamma/gamma + beta, Ni-Cr-Al couples.

  19. Xe isotope detection and discrimination using beta spectroscopy with coincident gamma spectroscopy

    NASA Astrophysics Data System (ADS)

    Reeder, P. L.; Bowyer, T. W.

    1998-02-01

    Beta spectroscopic techniques show promise of significant improvements for a beta-gamma coincidence counter that is part of a system for analyzing Xe automatically separated from air. The previously developed counting system for 131mXe, 133mXe, 133gXe, and 135gXe can be enhanced to give additional discrimination between these Xe isotopes by using the plastic scintillation sample cell as a beta spectrometer to resolve the conversion electron peaks. The automated system will be a key factor in monitoring the Comprehensive Test Ban Treaty.

  20. Gamma-ray spectroscopy and pulse shape discrimination with a plastic scintillator

    NASA Astrophysics Data System (ADS)

    van Loef, E.; Markosyan, G.; Shirwadkar, U.; McClish, M.; Shah, K.

    2015-07-01

    The scintillation properties of a novel plastic scintillator loaded with an organolead compound are presented. Under X-ray and gamma-ray excitation, emission is observed peaking at 435 nm. The scintillation light output is 9000 ph/MeV. An energy resolution (full width at half maximum over the peak position) of about 16% was observed for the 662 keV full absorption peak. Excellent pulse shape discrimination between neutrons and gamma-rays with a Figure of Merit of 2.6 at 1 MeVee was observed.

  1. DSC studies on gamma irradiated poly(vinylidene fluoride) applied to high gamma dose dosimetry

    NASA Astrophysics Data System (ADS)

    Batista, Adriana S. M.; Faria, Luiz O.

    2017-11-01

    Poly(vinylidene fluoride) homopolymer (PVDF) was investigated for use on high gamma dose dosimetry. Samples were irradiated with gamma doses ranging from 100 kGy to 3000 kGy. Differential scanning calorimetry (DSC) was used to construct an unambiguous relationship between the melting transition latent heat (LM) and the absorbed dose (D). DSC thermograms were taken immediately, 1, 2 and 8 months after the irradiation process revealing that the LMx D relationship presented no change for doses ranging from 100 to 2750 kGy. FTIR and UV-Vis spectroscopy data revealed the radio-induction of C˭O and C˭C bonds. These radio-induced bonds were responsible by the chain stiffening and chain oxidation, respectively. SEM microscopy demonstrates that the spherulitic large crystalline structures present in pristine PVDF are destroyed with doses as low as 100 kGy. The DRX analysis revealed that the main effect of high gamma doses in the crystalline structure of PVDF is to provoke a change from the pristine PVDF α-phase to the γ-phase. Both the ability to detect gamma doses in a large dose range and the low fading features make PVDF homopolymers good candidates to be investigated as high gamma dose dosimeters.

  2. Inverse Analysis of Irradiated NuclearMaterial Gamma Spectra via Nonlinear Optimization

    NASA Astrophysics Data System (ADS)

    Dean, Garrett James

    Nuclear forensics is the collection of technical methods used to identify the provenance of nuclear material interdicted outside of regulatory control. Techniques employed in nuclear forensics include optical microscopy, gas chromatography, mass spectrometry, and alpha, beta, and gamma spectrometry. This dissertation focuses on the application of inverse analysis to gamma spectroscopy to estimate the history of pulse irradiated nuclear material. Previous work in this area has (1) utilized destructive analysis techniques to supplement the nondestructive gamma measurements, and (2) been applied to samples composed of spent nuclear fuel with long irradiation and cooling times. Previous analyses have employed local nonlinear solvers, simple empirical models of gamma spectral features, and simple detector models of gamma spectral features. The algorithm described in this dissertation uses a forward model of the irradiation and measurement process within a global nonlinear optimizer to estimate the unknown irradiation history of pulse irradiated nuclear material. The forward model includes a detector response function for photopeaks only. The algorithm uses a novel hybrid global and local search algorithm to quickly estimate the irradiation parameters, including neutron fluence, cooling time and original composition. Sequential, time correlated series of measurements are used to reduce the uncertainty in the estimated irradiation parameters. This algorithm allows for in situ measurements of interdicted irradiated material. The increase in analysis speed comes with a decrease in information that can be determined, but the sample fluence, cooling time, and composition can be determined within minutes of a measurement. Furthermore, pulse irradiated nuclear material has a characteristic feature that irradiation time and flux cannot be independently estimated. The algorithm has been tested against pulse irradiated samples of pure special nuclear material with cooling times of

  3. Neutrons and gamma-rays spectroscopy of Mercury surface: global mapping from ESA MPO-BepiColombo spacecraft by MGNS instrument.

    NASA Astrophysics Data System (ADS)

    Kozyrev, A. S.; Gurvits, L. I.; Litvak, M. L.; Malakhov, A. A.; Mokrousov, M. I.; Mitrofanov, I. G.; Rogozhin, A. A.; Sanin, A. B.; Owens, A.; Schvetsov, V. N.

    2009-04-01

    For analyse chemistry composition of Mercury subsurface we will apply method of as-called remote sensing of neutrons. This method can be use for study celestial body of Solar system without thick atmospheres, like Moon, Mars, Phobos, Mercury etc. by the analysis of induced nuclear gamma-rays and neutron emission. These gamma-rays and neutrons are produced by energetic galactic cosmic rays colliding with nuclei of regolith within a 1-2 meter layer of subsurface. Mercury Planetary Orbiter of BepiColombo mission includes the nuclear instrument MGNS (Mercury Gamma-rays and Neutrons Spectrometers), which consists of gamma-rays spectrometer for detection of gamma-ray lines and neutron spectrometer for measurement of the neutron leakage flux. To test know theoretical models of Mercury composition, MGNS will provide the data for the set of gamma-ray lines, which are necessary and sufficient to discriminate between the models. Neutron data are known to be very sensitive for the presence of hydrogen within heavy soil-constituting elements. Mapping measurements of epithermal neutrons and 2.2 MeV line will allow us to study the content of hydrogen over the surface of Mercury and to test the presence of water ice deposits in the cold traps of permanently shadowed polar craters of this planet. There are also three natural radioactive elements, K, Th and U, which contents in the soil of a celestial body characterizes the physical condition of its formation in the proto-planetary cloud. The data from gamma-spectrometer will allow to compare the origin of Mercury with evolution of Earth, Moon and Mars. Three sensors for thermal and epithermal neutrons are made with similar 3He proportional counters, but have different polyethylene enclosures and cadmium shielding for different sensitivity of thermal and epithermal neutrons at different energy ranges. The fourth neutron sensor for high energy neutrons 1-10 MeV contains the scintillation crystal of stylbene with cylindrical shape of

  4. Dosimetric evaluation of lithium carbonate (Li2CO3) as a dosemeter for gamma-radiation dose measurements.

    PubMed

    Popoca, R; Ureña-Núñez, F

    2009-06-01

    This work reports the possibility of using lithium carbonate as a dosimetric material for gamma-radiation measurements. Carboxi-radical ions, CO(2)(-) and CO(3)(-), arise from the gamma irradiation of Li(2)CO(3), and these radical ions can be quantified by electron paramagnetic resonance (EPR) spectrometry. The EPR-signal response of gamma-irradiated lithium carbonate has been investigated to determine some dosimetric characteristics such as: peak-to-peak signal intensity versus gamma dose received, zero-dose response, signal fading, signal repeatability, batch homogeneity, dose rate effect and stability at different environmental conditions. Using the conventional peak-to-peak method of stable ion radicals, it is concluded that lithium carbonate could be used as a gamma dosemeter in the range of 3-100 Gy.

  5. High resolution gamma-ray spectroscopy and the fascinating angular momentum realm of the atomic nucleus

    NASA Astrophysics Data System (ADS)

    Riley, M. A.; Simpson, J.; Paul, E. S.

    2016-12-01

    In 1974 Aage Bohr and Ben Mottelson predicted the different ‘phases’ that may be expected in deformed nuclei as a function of increasing angular momentum and excitation energy all the way up to the fission limit. While admitting their picture was highly conjectural they confidently stated ‘...with the ingenious experimental approaches that are being developed, we may look forward with excitement to the detailed spectroscopic studies that will illuminate the behaviour of the spinning quantised nucleus’. High resolution gamma-ray spectroscopy has indeed been a major tool in studying the structure of atomic nuclei and has witnessed numerous significant advances over the last four decades. This article will select highlights from investigations at the Niels Bohr Institute, Denmark, and Daresbury Laboratory, UK, in the late 1970s and early 1980s, some of which have continued at other national laboratories in Europe and the USA to the present day. These studies illustrate the remarkable diversity of phenomena and symmetries exhibited by nuclei in the angular momentum-excitation energy plane that continue to surprise and fascinate scientists.

  6. Oxygen measurement by multimode diode lasers employing gas correlation spectroscopy.

    PubMed

    Lou, Xiutao; Somesfalean, Gabriel; Chen, Bin; Zhang, Zhiguo

    2009-02-10

    Multimode diode laser (MDL)-based correlation spectroscopy (COSPEC) was used to measure oxygen in ambient air, thereby employing a diode laser (DL) having an emission spectrum that overlaps the oxygen absorption lines of the A band. A sensitivity of 700 ppm m was achieved with good accuracy (2%) and linearity (R(2)=0.999). For comparison, measurements of ambient oxygen were also performed by tunable DL absorption spectroscopy (TDLAS) technique employing a vertical cavity surface emitting laser. We demonstrate that, despite slightly degraded sensitivity, the MDL-based COSPEC-based oxygen sensor has the advantages of high stability, low cost, ease-of-use, and relaxed requirements in component selection and instrument buildup compared with the TDLAS-based instrument.

  7. Radionuclide concentrations in soil and lifetime cancer risk due to gamma radioactivity in Kirklareli, Turkey.

    PubMed

    Taskin, H; Karavus, M; Ay, P; Topuzoglu, A; Hidiroglu, S; Karahan, G

    2009-01-01

    The objective of this study is to evaluate and map soil radionuclides' activity concentrations and environmental outdoor gamma dose rates (terrestrial and cosmic) in Kirklareli, Turkey. The excess lifetime cancer risks are also calculated. Outdoor gamma dose rates were determined in 230 sampling stations and soil samples were taken from 177 locations. The coordinates of the readings were determined by the Global Positioning System (GPS). The outdoor gamma dose rates were determined by Eberline smart portable device (ESP-2) and measurements were taken in air for two minutes at 1m from the ground. The average outdoor gamma dose rate was 118+/-34nGyh(-1). Annual effective gamma dose of Kirklareli was 144microSv and the excess lifetime cancer risk of 5.0x10(-4). Soil samples were analyzed by gamma spectroscopy. The average 226Ra, 238U, 232Th, 137Cs, and 40K activities were 37+/-18Bqkg(-1), 28+/-13Bqkg(-1), 40+/-18Bqkg(-1), 8+/-5Bqkg(-1) and 667+/-281Bqkg(-1), respectively. The average soil radionuclides' concentrations of Kirklareli were within the worldwide range although some extreme values had been determined. Annual effective gamma doses and the excess lifetime risks of cancer were higher than the world's average.

  8. A 3D simulation look-up library for real-time airborne gamma-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Kulisek, Jonathan A.; Wittman, Richard S.; Miller, Erin A.; Kernan, Warnick J.; McCall, Jonathon D.; McConn, Ron J.; Schweppe, John E.; Seifert, Carolyn E.; Stave, Sean C.; Stewart, Trevor N.

    2018-01-01

    A three-dimensional look-up library consisting of simulated gamma-ray spectra was developed to leverage, in real-time, the abundance of data provided by a helicopter-mounted gamma-ray detection system consisting of 92 CsI-based radiation sensors and exhibiting a highly angular-dependent response. We have demonstrated how this library can be used to help effectively estimate the terrestrial gamma-ray background, develop simulated flight scenarios, and to localize radiological sources. Source localization accuracy was significantly improved, particularly for weak sources, by estimating the entire gamma-ray spectra while accounting for scattering in the air, and especially off the ground.

  9. The effect of gamma irradiation on rice protein aqueous solution

    NASA Astrophysics Data System (ADS)

    Baccaro, Stefania; Bal, Oya; Cemmi, Alessia; Di Sarcina, Ilaria

    2018-05-01

    The use of proteins as natural biopolymers are sensibly increasing in several application fields such as food industry, packaging and environment protection. In particular, rice proteins (RP) present good nutritional, hypoallergenic and healthful properties very interesting for human consumption. Since ionizing radiation can be successfully applied on protein containing systems involved in different industrial processes, this work aims to determine the effect of gamma radiation on 5 wt%-7.5 wt% RP aqueous solutions in a wide range of absorbed doses up to around 40 kGy. The changes of RP secondary and tertiary structures and their chemical composition were followed by UV-VIS absorbance spectroscopy, luminescence analysis and pH measurements. The experimental data showed the occurrence of the unfolding of RP chains with the increase of the absorbed dose and the formation of new molecules, due to the reaction among tryptophane and tyrosine amino acids and the radical species induced by gamma radiation. The results are also confirmed by the modification of the pH values measured for the irradiated solutions.

  10. PhD Dissertation Proposal - Introduction to Dark Mix Concept: Gamma Measurements of Capsule Mixture

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Meaney, Kevin Daniel

    Presentation slides: Intro to Inertial Confinement Fusion; Types of Mixture in ICF capsules; Previous mixture experiments; Dark Mix Concept; Measuring Dark Mix with Gamma Cherenkov Detector; Dissertation Outline.

  11. Levels of naturally occurring gamma radiation measured in British homes and their prediction in particular residences.

    PubMed

    Kendall, G M; Wakeford, R; Athanson, M; Vincent, T J; Carter, E J; McColl, N P; Little, M P

    2016-03-01

    Gamma radiation from natural sources (including directly ionising cosmic rays) is an important component of background radiation. In the present paper, indoor measurements of naturally occurring gamma rays that were undertaken as part of the UK Childhood Cancer Study are summarised, and it is shown that these are broadly compatible with an earlier UK National Survey. The distribution of indoor gamma-ray dose rates in Great Britain is approximately normal with mean 96 nGy/h and standard deviation 23 nGy/h. Directly ionising cosmic rays contribute about one-third of the total. The expanded dataset allows a more detailed description than previously of indoor gamma-ray exposures and in particular their geographical variation. Various strategies for predicting indoor natural background gamma-ray dose rates were explored. In the first of these, a geostatistical model was fitted, which assumes an underlying geologically determined spatial variation, superimposed on which is a Gaussian stochastic process with Matérn correlation structure that models the observed tendency of dose rates in neighbouring houses to correlate. In the second approach, a number of dose-rate interpolation measures were first derived, based on averages over geologically or administratively defined areas or using distance-weighted averages of measurements at nearest-neighbour points. Linear regression was then used to derive an optimal linear combination of these interpolation measures. The predictive performances of the two models were compared via cross-validation, using a randomly selected 70 % of the data to fit the models and the remaining 30 % to test them. The mean square error (MSE) of the linear-regression model was lower than that of the Gaussian-Matérn model (MSE 378 and 411, respectively). The predictive performance of the two candidate models was also evaluated via simulation; the OLS model performs significantly better than the Gaussian-Matérn model.

  12. Gamma-Ray Pulse Tube Cooler Development and Testing

    NASA Technical Reports Server (NTRS)

    Ross, R.; Johnson, D.; Kotsubo, V.; Evtimov, B.; Olson, J.; Nast, T.; Rawlings, R.

    2000-01-01

    For a variety of space-science applications, such as gamma-ray spectroscopy, the introduction of cryogenic cooling via a cryocooler can greatly increase the potential science return by allowing the use of more sensitive and lower noise detectors.

  13. Measuring the radium quartet (228Ra, 226Ra, 224Ra, 223Ra) in seawater samples using gamma spectrometry.

    PubMed

    van Beek, P; Souhaut, M; Reyss, J-L

    2010-07-01

    Radium isotopes are widely used in marine studies (eg. to trace water masses, to quantify mixing processes or to study submarine groundwater discharge). While 228Ra and 226Ra are usually measured using gamma spectrometry, short-lived Ra isotopes (224Ra and 223Ra) are usually measured using a Radium Delayed Coincidence Counter (RaDeCC). Here we show that the four radium isotopes can be analyzed using gamma spectrometry. We report 226Ra, 228Ra, 224Ra, 223Ra activities measured using low-background gamma spectrometry in standard samples, in water samples collected in the vicinity of our laboratory (La Palme and Vaccarès lagoons, France) but also in seawater samples collected in the plume of the Amazon river, off French Guyana (AMANDES project). The 223Ra and 224Ra activities determined in these samples using gamma spectrometry were compared to the activities determined using RaDeCC. Activities determined using the two techniques are in good agreement. Uncertainties associated with the 224Ra activities are similar for the two techniques. RaDeCC is more sensitive for the detection of low 223Ra activities. Gamma spectrometry thus constitutes an alternate method for the determination of short-lived Ra isotopes. 2009 Elsevier Ltd. All rights reserved.

  14. Fermi GBM Observations of Terrestrial Gamma Flashes

    NASA Technical Reports Server (NTRS)

    Wilson-Hodge, Colleen A.; Briggs, M. S.; Connaughton, V.; Fishman, G. J.; Bhat, P. N.; Paciesas, W. S.; Preece, R. D.; Kippen, R. M.; vonKienlin, A.; Dwyer, J. R.; hide

    2010-01-01

    In its first two years of operation, the Fermi Gamma Ray Burst Monitor (GBM) has observed 79 Terrestrial Gamma Flashes (TGFs). The thick Bismuth Germanate (BGO) detectors are excellent for TGF spectroscopy, having a high probability of recording the full energy of an incident photon, spanning a broad energy range from 150 keV to 40 MeV, and recording a large number of photons per TGF. Correlations between GBM TGF triggers and lightning sferics detected with the World-Wide Lightning Location Network indicate that TGFs and lightning are simultaneous to within tens of microseconds.

  15. Monte-Carlo Simulation and Measurements of Electrons, Positrons, And Gamma-Rays Generated by Laser-Solid Interactions

    NASA Astrophysics Data System (ADS)

    Henderson, Alexander Hastings

    Lasers have grown more powerful in recent years, opening up new frontiers in physics. From early intensities of less than 1010 W/cm 2, lasers can now achieve intensities over 1021 W/cm 2. Ultraintense laser can become powerful new tools to produce relativistic electrons, positron-electron pairs, and gamma-rays. The pair production efficiency is equal to or greater than that of linear accelerators, the most common method of antimatter generation in the past. The gamma-rays and electrons produced can be highly collimated, making these interactions of interest for beam generation. Monte-Carlo particle transport simulation has long been used in physics for simulating various particle and radiation processes, and is well-suited to simulating both electromagnetic cascades resulting from laser-solid interactions and the response of electron/positron spectrometers and gamma-ray detectors. We have used GEANT4 Monte-Carlo particle transport simulation to design and calibrate charged-particle spectrometers using permanent magnets as well as a Forward Compton Electron Spectrometer to measure gamma-rays of higher energies than have previously been achieved. We have had some success simulating and measuring high positron and gamma-rays yields from laser-solid interactions using gold target at the Texas Petawatt Laser (TPW). While similar spectrometers have been developed in the past, we are to our knowledge the first to successfully use permanent magnet spectrometers to detect positrons originating from laser-solid interactions in this energy range. We believe we are also the first to successfully detect multi-MeV gamma rays using a permanent magnet Forward Compton Electron Spectrometer. Monte-Carlo particle transport simulation has been used by other groups to model positron production from laser-solid ineraction, but at the time that we began we were, as far as we know, the first to have a significant amount of empirical data to work with. We were thus at liberty to estimate

  16. Preliminary design and performance of an advanced gamma ray spectrometer for future orbiter missions. [composition and evolution of planets

    NASA Technical Reports Server (NTRS)

    Metzger, A. E.; Parker, R. H.; Arnold, J. R.; Reedy, R. C.; Trombka, J. I.

    1975-01-01

    A knowledge of the composition of planets, satellites, and asteroids is of primary importance in understanding the formation and evolution of the solar system. Gamma-ray spectroscopy is capable of measuring the composition of meter-depth surface material from orbit around any body possessing little or no atmosphere. Measurement sensitivity is determined by detector efficiency and resolution, counting time, and the background flux while the effective spatial resolution depends upon the field-of-view and counting time together with the regional contrast in composition. The advantages of using germanium as a detector of gamma rays in space are illustrated experimentally and a compact instrument cooled by passive thermal radiation is described. Calculations of the expected sensitivity of this instrument at the Moon and Mars show that at least a dozen elements will be detected, twice the number which have been isolated in the Apollo gamma-ray data.

  17. New concepts for scintillator/HgI[sub 2] gamma ray spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Y.J.; Iwanczyk, J.S.; Patt, B.E.

    The construction of a high energy resolution gamma ray detector consisting of a scintillator/mercuric iodide photodetector combination has been investigated. Several HgI[sub 2] photodetectors have been fabricated and tested with standard NIM electronics. The energy resolution of a scintillator/HgI[sub 2] pair was found to be 4.75%, full width at half maximum, for 662 keV [sup 137]Cs gamma ray photons. Of five detectors fabricated with the new technique, all produced resolutions better than 5.6% FWHM. This technology makes it possible to reliably produce high quality HgI[sub 2] photodetectors. New design concepts for the HgI[sub 2] photocell, including the transparent entrance electrode,more » detector geometry, and detector packaging, are described in the paper. Advantages of gamma ray spectrometers based upon crystal scintillators optically coupled to HgI[sub 2] photodetectors (in contrast to coupling the scintillators to the more conventional light sensors, i.e., photomultiplier tubes (PMTs)) include greater ruggedness, improved energy resolution, markedly smaller size and weight, reduced power, and insensitivity to magnetic field perturbations.« less

  18. ESR identification of gamma-irradiated albendazole

    NASA Astrophysics Data System (ADS)

    Çolak, Seyda

    2010-01-01

    The use of ionizing radiation for sterilization of pharmaceuticals is a well-established technology. In the present work, the spectroscopic and kinetic features of the radicals induced in gamma-irradiated solid albendazole samples is investigated at different temperatures in the dose range of 3-34 kGy by electron spin resonance (ESR) spectroscopy. Irradiation with gamma radiation produced two different radical species in albendazole. They were fairly stable at room temperature but relatively unstable above room temperature, giving rise to an unresolved ESR spectrum consisting of three resonance peaks centered at g=2.0057. Decay activation energies of the contributing radical species were calculated to be 47.8 (±13.5) and 50.5 (±9.7) kJ/mol using the signal intensity decay data derived from annealing studies performed at high temperatures. A linear function of the applied dose was found to best describe the experimental dose-response data. Albendazole does not present the characteristics of good dosimetric materials. However, the discrimination of irradiated albendazole from its unirradiated form was possible even 6 months after storage in normal conditions. Based on these findings, it is concluded that albendazole and albendazole-containing drugs can be safely sterilized by gamma radiation and that ESR spectroscopy could be successfully used as a potential technique for monitoring their radiosterilization.

  19. Measurements of environmental terrestrial gamma radiation dose rate in three mountainous locations in the western region of Saudi Arabia

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Al-Ghorabie, Fayez H.H.

    2005-06-01

    This paper describes measurements of external gamma radiation dose rate from terrestrial gamma-rays 1 m above the ground in three different mountainous locations in the western region of the Kingdom of Saudi Arabia. These locations are At-Taif city, Al-Hada village, and Ash-Shafa village. CaSO{sub 4}:Dy (TLD-900) thermoluminescent dosimeters were used for the detection of terrestrial gamma radiation at 40 different places in the three locations. The values of terrestrial gamma radiation dose rate measured ranged between 14 and 279 nGy h{sup -1} for the time interval from June 2001 to June 2002. The measured dose rate varied with the seasonmore » of the year. The average gamma radiation dose rates were 468, 541, and 781 {mu}Gy y{sup -1} for At-Taif city, Al-Hada village, and Ash-Shafa village, respectively. The corresponding average absorbed doses to the population of the three locations were 328, 379, and 547 {mu}Sv y{sup -1}, respectively. The quality factor of 0.7 Sv Gy{sup -1} was applied in the calculations of the absorbed dose to humans.« less

  20. Measurement of the Effective Weak Mixing Angle in $$p\\bar{p}\\rightarrow Z/\\gamma^* \\rightarrow \\ell^+\\ell^-$$ Events

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Abazov, Victor Mukhamedovich; et al.

    2017-10-11

    We present a measurement of the effective weak mixing angle parametermore » $$\\sin^2\\theta_\\text{eff}^{\\ell}$$, in $$p\\bar{p}\\rightarrow Z/\\gamma^* \\rightarrow \\mu^+\\mu^-$$ events at a center of mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron Collider and corresponding to 8.6 fb$$^{-1}$$ of integrated luminosity. The measured value of $$\\sin^2\\theta_\\text{eff}^{\\ell}[\\mu\\mu]=0.23016 \\pm 0.00064$$ is further combined with the result from the D0 measurement in $$p\\bar{p}\\rightarrow Z/\\gamma^{*}\\rightarrow e^{+} e^{-}$$ events, resulting in $$\\sin^2\\theta_\\text{eff}^{\\ell} [\\text{comb.}]=0.23095 \\pm 0.00040$$. This combined result is the most precise measurement from a single experiment at a hadron collider and is the most precise determination using the coupling of the $$Z/\\gamma^*$$ to light quarks.« less

  1. Modeled Martian subsurface elemental composition measurements with the Probing In situ with Neutron and Gamma ray instrument

    NASA Astrophysics Data System (ADS)

    Nowicki, Suzanne F.; Evans, Larry G.; Starr, Richard D.; Schweitzer, Jeffrey S.; Karunatillake, Suniti; McClanahan, Timothy P.; Moersch, Jeffrey E.; Parsons, Ann M.; Tate, Christopher G.

    2017-02-01

    The Probing In situ with Neutron and Gamma ray (PING) instrument is an innovative application of active neutron-induced gamma ray technology. The objective of PING is to measure the elemental composition of the Martian regolith. This manuscript presents PING's sensitivities as a function of the Martian regolith depth and PING's uncertainties in the measurements as a function of observation time in passive and active mode. The modeled sensitivities show that in PING's active mode, where both a pulsed neutron generator (PNG) and a gamma ray spectrometer (GRS) are used, PING can interrogate the material below the rover to about 20 cm due to the penetrating nature of the high-energy neutrons and the resulting secondary gamma rays observed with the GRS. PING is capable of identifying most major and minor rock-forming elements, including H, O, Na, Mn, Mg, Al, Si, P, S, Cl, Cr, K, Ca, Ti, Fe, and Th. The modeled uncertainties show that PING's use of a PNG reduces the required observation times by an order of magnitude over a passive operating mode where the PNG is turned off. While the active mode allows for more complete elemental inventories with higher sensitivity, the gamma ray signatures of some elements are strong enough to detect in passive mode. We show that PING can detect changes in key marker elements and make thermal neutron measurements in about 1 min that are sensitive to H and Cl.

  2. EVIDENCE FOR ENHANCED {sup 3}HE IN FLARE-ACCELERATED PARTICLES BASED ON NEW CALCULATIONS OF THE GAMMA-RAY LINE SPECTRUM

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Murphy, R. J.; Kozlovsky, B.; Share, G. H., E-mail: murphy@ssd5.nrl.navy.mil, E-mail: benz@wise.tau.ac.il, E-mail: share@astro.umd.edu

    2016-12-20

    The {sup 3}He abundance in impulsive solar energetic particle (SEP) events is enhanced up to several orders of magnitude compared to its photospheric value of [{sup 3}He]/[{sup 4}He] = 1–3 × 10{sup −4}. Interplanetary magnetic field and timing observations suggest that these events are related to solar flares. Observations of {sup 3}He in flare-accelerated ions would clarify the relationship between these two phenomena. Energetic {sup 3}He interactions in the solar atmosphere produce gamma-ray nuclear-deexcitation lines, both lines that are also produced by protons and α particles and lines that are essentially unique to {sup 3}He. Gamma-ray spectroscopy can, therefore, reveal enhanced levelsmore » of accelerated {sup 3}He. In this paper, we identify all significant deexcitation lines produced by {sup 3}He interactions in the solar atmosphere. We evaluate their production cross sections and incorporate them into our nuclear deexcitation-line code. We find that enhanced {sup 3}He can affect the entire gamma-ray spectrum. We identify gamma-ray line features for which the yield ratios depend dramatically on the {sup 3}He abundance. We determine the accelerated {sup 3}He/ α ratio by comparing these ratios with flux ratios measured previously from the gamma-ray spectrum obtained by summing the 19 strongest flares observed with the Solar Maximum Mission Gamma-Ray Spectrometer. All six flux ratios investigated show enhanced {sup 3}He, confirming earlier suggestions. The {sup 3}He/ α weighted mean of these new measurements ranges from 0.05 to 0.3 (depending on the assumed accelerated α /proton ratio) and has a <1 × 10{sup −3} probability of being consistent with the photospheric value. With the improved code, we can now exploit the full potential of gamma-ray spectroscopy to establish the relationship between flare-accelerated ions and {sup 3}He-rich SEPs.« less

  3. Currie detection limits in gamma-ray spectroscopy.

    PubMed

    De Geer, Lars-Erik

    2004-01-01

    Currie Hypothesis testing is applied to gamma-ray spectral data, where an optimum part of the peak is used and the background is considered well known from nearby channels. With this, the risk of making Type I errors is about 100 times lower than commonly assumed. A programme, PeakMaker, produces random peaks with given characteristics on the screen and calculations are done to facilitate a full use of Poisson statistics in spectrum analyses. SHORT TECHNICAL NOTE SUMMARY: The Currie decision limit concept applied to spectral data is reinterpreted, which gives better consistency between the selected error risk and the observed error rates. A PeakMaker program is described and the few count problem is analyzed.

  4. Comparison of electrical capacitance tomography and gamma densitometer measurement in viscous oil-gas flows

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Archibong Eso, A.; Zhao, Yabin; Yeung, Hoi

    2014-04-11

    Multiphase flow is a common occurrence in industries such as nuclear, process, oil and gas, food and chemical. A prior knowledge of its features and characteristics is essential in the design, control and management of such processes due to its complex nature. Electrical Capacitance Tomography (ECT) and Gamma Densitometer (Gamma) are two promising approaches for multiphase visualization and characterization in process industries. In two phase oil and gas flow, ECT and Gamma are used in multiphase flow monitoring techniques due to their inherent simplicity, robustness, and an ability to withstand wide range of operational temperatures and pressures. High viscous oilmore » (viscosity > 100 cP) is of interest because of its huge reserves, technological advances in its production and unlike conventional oil (oil viscosity < 100 cP) and gas flows where ECT and Gamma have been previously used, high viscous oil and gas flows comes with certain associated concerns which include; increased entrainment of gas bubbles dispersed in oil, shorter and more frequent slugs as well as oil film coatings on the walls of flowing conduits. This study aims to determine the suitability of both devices in the visualization and characterization of high-viscous oil and gas flow. Static tests are performed with both devices and liquid holdup measurements are obtained. Dynamic experiments were also conducted in a 1 and 3 inch facility at Cranfield University with a range of nominal viscosities (1000, 3000 and 7500 cP). Plug, slug and wavy annular flow patterns were identified by means of Probability Mass Function and time series analysis of the data acquired from Gamma and ECT devices with high speed camera used to validate the results. Measured Liquid holdups for both devices were also compared.« less

  5. A study of interdiffusion in beta + gamma/gamma + gamma prime Ni-Cr-Al. M.S. Thesis. Final Report

    NASA Technical Reports Server (NTRS)

    Carol, L. A.

    1985-01-01

    Ternary diffusion in the NiCrAl system at 1200 C was studied with beta + gamma/gamma + gamma prime infinite diffusion couples. Interdiffusion resulted in the formation of complex, multiphase diffusion zones. Concentration/distance profiles for Cr and Al in the phases present in the diffusion zone were measured after 200 hr. The Ni-rich portion of the NiCrAl phase diagram (1200 C) was also determined. From these data, bulk Cr and Al profiles were calculated and translated to diffusion paths on the ternary isotherm. Growth layer kinetics of the layers present in the diffusion zone were also measured.

  6. Measurement of angularly dependent spectra of betatron gamma-rays from a laser plasma accelerator with quadrant-sectored range filters

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jeon, Jong Ho, E-mail: jhjeon07@ibs.re.kr; Nakajima, Kazuhisa, E-mail: naka115@dia-net.ne.jp; Rhee, Yong Joo

    Measurement of angularly dependent spectra of betatron gamma-rays radiated by GeV electron beams from laser wakefield accelerators (LWFAs) are presented. The angle-resolved spectrum of betatron radiation was deconvolved from the position dependent data measured for a single laser shot with a broadband gamma-ray spectrometer comprising four-quadrant sectored range filters and an unfolding algorithm, based on the Monte Carlo code GEANT4. The unfolded gamma-ray spectra in the photon energy range of 0.1–10 MeV revealed an approximately isotropic angular dependence of the peak photon energy and photon energy-integrated fluence. As expected by the analysis of betatron radiation from LWFAs, the results indicate thatmore » unpolarized gamma-rays are emitted by electrons undergoing betatron motion in isotropically distributed orbit planes.« less

  7. Measuring B to S Gamma, B to D Gamma and |V(Td)/V(Ts)| at BaBar

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bard, Deborah; /SLAC

    2012-06-01

    Using a sample of 471 million B{bar B} events collected with the BaBar detector, we study the sum of seven exclusive final states b {yields} X{sub s(d)}{gamma}, where X{sub s(d)} is a strange (non-strange) hadronic system with a mass of up to 2.0 Gev/c{sup 2}. After correcting for unobserved decay modes, we obtain a branching fraction for b {yields} d{gamma} of (9.2 {+-} 2.0(stat.) {+-} 2.3(syst.)) x 10{sup -6} in this mass range, and a branching fraction for b {yields} s{gamma} of (23.0 {+-} 0.8(stat.) {+-} 3.0(syst.)) x 10{sup -5} in the same mass range. We find BF(b {yields} d{gamma})/BF(bmore » {yields} s{gamma}) = 0.040 {+-} 0.009(stat.) {+-} 0.010(syst.), from which we determine |V{sub td}/V{sub ts}| = 0.199 {+-} 0.022(stat.) {+-} 0.024(syst.) {+-} 0.002(th.).« less

  8. A Correlated Optical and Gamma Emission from GRB 081126A

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gendre, B.; Klotz, A.; CESR, Observatoire Midi-Pyrenees, CNRS, Universite de Toulouse, BP 4346, F-31028-Toulouse Cedex 04

    2010-10-15

    We present an analysis of time-resolved optical emissions observed from the gamma-ray burst GRB 081126 during the prompt phase. The analysis employed time-resolved photometry using optical data obtained by the TAROT telescope, BAT data from the Swift spacecraft and time-resolved spectroscopy at high energies from the GBM instrument onboard the Fermi spacecraft. The optical emission of GRB 081126 is found to be compatible with the second gamma emission pulse shifted by a positive time-lag of 8.4{+-}3.9 sec. This is the first well resolved observation of a time lag between optical and gamma emissions during a gamma-ray burst. Our observations couldmore » potentially provide new constraints on the fireball model for gamma ray burst early emissions. Furthermore, observations of time-lags between optical and gamma ray photons provides an exciting opportunity to constrain quantum gravity theories.« less

  9. BiI 3 Crystals for High Energy Resolution Gamma-Ray Spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nino, Juan C.; Baciak, James; Johns, Paul

    2017-04-12

    BiI 3 had been investigated for its unique properties as a layered compound semiconductor for many decades. However, despite the exceptional atomic, physical, and electronic properties of this material, good resolution gamma ray spectra had never been reported for BiI 3. The shortcomings that previously prevented BiI 3 from reaching success as a gamma ray sensor were, through this project, identified and suppressed to unlock the performance of this promising compound. Included in this work were studies on a number of methods which have, for the first time, enabled BiI 3 to exhibit spectral performance rivaling many other candidate semiconductorsmore » for room temperature gamma ray sensors. New approaches to crystal growth were explored that allow BiI 3 spectrometers to be fabricated with up to 2.2% spectral resolution at 662 keV. Fundamental studies on trap states, dopant incorporation, and polarization were performed to enhance performance of this compound. Additionally, advanced detection techniques were applied to display the capabilities of high quality BiI 3 spectrometers. Overall, through this work, BiI 3 has been revealed as a potentially transformative material for nuclear security and radiation detection sciences.« less

  10. Validation of gamma-ray detection techniques for safeguards monitoring at natural uranium conversion facilities

    DOE PAGES

    Dewji, Shaheen A.; Lee, Denise L.; Croft, Stephen; ...

    2016-03-28

    Recent IAEA circulars and policy papers have sought to implement safeguards when any purified aqueous uranium solution or uranium oxides suitable for isotopic enrichment or fuel fabrication exists. Under the revised policy, IAEA Policy Paper 18, the starting point for nuclear material under safeguards was reinterpreted, suggesting that purified uranium compounds should be subject to safeguards procedures no later than the first point in the conversion process. In response to this technical need, a combination of simulation models and experimental measurements were employed to develop and validate concepts of nondestructive assay monitoring systems in a natural uranium conversion plant (NUCP).more » In particular, uranyl nitrate (UO 2(NO 3) 2) solution exiting solvent extraction was identified as a key measurement point (KMP), where gamma-ray spectroscopy was selected as the process monitoring tool. The Uranyl Nitrate Calibration Loop Equipment (UNCLE) facility at Oak Ridge National Laboratory was employed to simulate the full-scale operating conditions of a purified uranium-bearing aqueous stream exiting the solvent extraction process in an NUCP. Nondestructive assay techniques using gamma-ray spectroscopy were evaluated to determine their viability as a technical means for drawing safeguards conclusions at NUCPs, and if the IAEA detection requirements of 1 significant quantity (SQ) can be met in a timely way. This work investigated gamma-ray signatures of uranyl nitrate circulating in the UNCLE facility and evaluated various gamma-ray detector sensitivities to uranyl nitrate. These detector validation activities include assessing detector responses to the uranyl nitrate gamma-ray signatures for spectrometers based on sodium iodide, lanthanum bromide, and high-purity germanium detectors. The results of measurements under static and dynamic operating conditions at concentrations ranging from 10–90 g U/L of natural uranyl nitrate are presented. A range of gamma

  11. Validation of gamma-ray detection techniques for safeguards monitoring at natural uranium conversion facilities

    NASA Astrophysics Data System (ADS)

    Dewji, S. A.; Lee, D. L.; Croft, S.; Hertel, N. E.; Chapman, J. A.; McElroy, R. D.; Cleveland, S.

    2016-07-01

    Recent IAEA circulars and policy papers have sought to implement safeguards when any purified aqueous uranium solution or uranium oxides suitable for isotopic enrichment or fuel fabrication exists. Under the revised policy, IAEA Policy Paper 18, the starting point for nuclear material under safeguards was reinterpreted, suggesting that purified uranium compounds should be subject to safeguards procedures no later than the first point in the conversion process. In response to this technical need, a combination of simulation models and experimental measurements were employed to develop and validate concepts of nondestructive assay monitoring systems in a natural uranium conversion plant (NUCP). In particular, uranyl nitrate (UO2(NO3)2) solution exiting solvent extraction was identified as a key measurement point (KMP), where gamma-ray spectroscopy was selected as the process monitoring tool. The Uranyl Nitrate Calibration Loop Equipment (UNCLE) facility at Oak Ridge National Laboratory was employed to simulate the full-scale operating conditions of a purified uranium-bearing aqueous stream exiting the solvent extraction process in an NUCP. Nondestructive assay techniques using gamma-ray spectroscopy were evaluated to determine their viability as a technical means for drawing safeguards conclusions at NUCPs, and if the IAEA detection requirements of 1 significant quantity (SQ) can be met in a timely way. This work investigated gamma-ray signatures of uranyl nitrate circulating in the UNCLE facility and evaluated various gamma-ray detector sensitivities to uranyl nitrate. These detector validation activities include assessing detector responses to the uranyl nitrate gamma-ray signatures for spectrometers based on sodium iodide, lanthanum bromide, and high-purity germanium detectors. The results of measurements under static and dynamic operating conditions at concentrations ranging from 10-90 g U/L of natural uranyl nitrate are presented. A range of gamma-ray lines is

  12. One-dimensional Spatial Distributions of Gamma-ray Emitting Contaminants in Field Lysimeters Using a Collimated Gamma-ray Spectroscopy System.

    PubMed

    Erdmann, Bryan J; Powell, Brian A; Kaplan, Daniel I; DeVol, Timothy A

    2018-05-01

    One-dimensional scans of gamma-ray emitting contaminants were conducted on lysimeters from the RadFLEX facility at the Savannah River Nationals Laboratory (SRNL). The lysimeters each contained a contamination source that was buried in SRNL soil. A source consisted of Cs, Co, Ba, and Eu incorporated either into a solid waste form (Portland cement and reducing grout) or applied to a filter paper for direct soil exposure. The lysimeters were exposed to natural environmental conditions for 3 to 4 y. The initial contaminant activities range from 4.0 to 9.0 MBq for the solid wasteforms and 0.25 to 0.47 MBq for the soil-incorporated source. The measurements were performed using a collimated high-purity germanium gamma-ray spectrometer with a spatial resolution of 2.5 mm. These scans showed downward mobility of Co and Ba when the radionuclides were incorporated directly into the SRNL soil. When radionuclides were incorporated into the solid waste forms positioned in the SRNL soil, Cs exhibited both upward and downward dispersion while the other radionuclides showed no movement. This dispersion was more significant for the Portland cement than the reducing grout wasteform. Europium-152 was the only radionuclide of those studied that showed no movement within the spatial resolution of the scanner from the original placement within the lysimeter. Understanding radionuclide movement in the environment is important for developing strategies for waste management and disposal.

  13. A deep-level transient spectroscopy study of gamma-ray irradiation on the passivation properties of silicon nitride layer on silicon

    NASA Astrophysics Data System (ADS)

    Dong, Peng; Yu, Xuegong; Ma, Yao; Xie, Meng; Li, Yun; Huang, Chunlai; Li, Mo; Dai, Gang; Zhang, Jian

    2017-08-01

    Plasma-enhanced chemical vapor deposited silicon nitride (SiNx) films are extensively used as passivation material in the solar cell industry. Such SiNx passivation layers are the most sensitive part to gamma-ray irradiation in solar cells. In this work, deep-level transient spectroscopy has been applied to analyse the influence of gamma-ray irradiation on the passivation properties of SiNx layer on silicon. It is shown that the effective carrier lifetime decreases with the irradiation dose. At the same time, the interface state density is significantly increased after irradiation, and its energy distribution is broadened and shifts deeper with respect to the conduction band edge, which makes the interface states becoming more efficient recombination centers for carriers. Besides, C-V characteristics show a progressive negative shift with increasing dose, indicating the generation of effective positive charges in SiNx films. Such positive charges are beneficial for shielding holes from the n-type silicon substrates, i. e. the field-effect passivation. However, based on the reduced carrier lifetime after irradiation, it can be inferred that the irradiation induced interface defects play a dominant role over the trapped positive charges, and therefore lead to the degradation of passivation properties of SiNx on silicon.

  14. Observational techniques for solar flare gamma-rays, hard X-rays, and neutrons

    NASA Technical Reports Server (NTRS)

    Lin, Robert P.

    1989-01-01

    The development of new instrumentation and techniques for solar hard X-ray, gamma ray and neutron observations from spacecraft and/or balloon-borne platforms is examined. The principal accomplishments are: (1) the development of a two segment germanium detector which is near ideal for solar hard X-ray and gamma ray spectroscopy; (2) the development of long duration balloon flight techniques and associated instrumentation; and (3) the development of innovative new position sensitive detectors for hard X-ray and gamma rays.

  15. Microstructure and Mechanical Properties in Gamma(face-centered cubic) + Gamma Prime(L12) Precipitation-Strengthened Cobalt-based Superalloys

    NASA Astrophysics Data System (ADS)

    Bocchini, Peter J.

    -ray spectroscopy (EDS) in alloys with coarse microstructures. High-temperature mechanical properties are determined with compression creep at 850 °C and flow stress tests conducted between room temperature and 900 °C. gamma'(L12)-solvus temperature, as well as solidus and liquidus temperatures, are measured with differential thermal analysis (DTA). B and Zr strongly segregate to GBs in Co-Al-W-B-Zr alloys. B additions of 0.05 at. % result in micron-sized GB-precipitates that improve creep strength by two orders of magnitude. Segregation of B or Zr in amounts where GB-precipitates do not form, have no effect on creep strength over a ternary Co-Al-W alloy. The concurrent addition of B and Zr improves creep strength, though to a lesser degree than in alloys containing GB-borides. Ti is an effective substitute for W and Al in Co-Ni-Al-W alloys where density is decreased by 9 % and solvus is increased to 1137 °C in a Co-10Ni-5Al-5W-8Ti at. % alloy compared to 982 °C in a Co-10Ni-9Al-9W at. % alloy. Further investigation of reducing W in a Co-10Ni-6Al-xW-6Ti at. % (x=6, 4, 2, 0) alloys ascertain that, with the addition of Ti, gamma'(L12)-precipitates can form in a wider composition range than in ternary Co-Al-W alloys. 2-D dislocation dynamics simulations are in good agreement with experimental measurements for binary Ni-Al and ternary Co-Al-W alloys. General trends in strengthening are captured for higher order Ni-Al-Cr and Ni-Al-Cr-W alloys.

  16. Numerical study on determining formation porosity using a boron capture gamma ray technique and MCNP.

    PubMed

    Liu, Juntao; Zhang, Feng; Wang, Xinguang; Han, Fei; Yuan, Zhelong

    2014-12-01

    Formation porosity can be determined using the boron capture gamma ray counting ratio with a near to far detector in a pulsed neutron-gamma element logging tool. The thermal neutron distribution, boron capture gamma spectroscopy and porosity response for formations with different water salinity and wellbore diameter characteristics were simulated using the Monte Carlo method. We found that a boron lining improves the signal-to-noise ratio and that the boron capture gamma ray counting ratio has a higher sensitivity for determining porosity than total capture gamma. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Dynamic cerebral autoregulation measured with coherent hemodynamics spectroscopy (CHS)

    NASA Astrophysics Data System (ADS)

    Kainerstorfer, Jana M.; Sassaroli, Angelo; Tgavalekos, Kristen T.; Fantini, Sergio

    2015-03-01

    Coherent Hemodynamics Spectroscopy (CHS) is a novel technique for non-invasive measurements of local microcirculation quantities such as the capillary blood transit times and dynamic autoregulation. The basis of CHS is to measure, for instance with near-infrared spectroscopy (NIRS), peripheral coherent hemodynamic changes that are induced by controlled perturbations in the systemic mean arterial pressure (MAP). In this study, the MAP perturbation was induced by the fast release of two pneumatic cuffs placed around the subject's thighs after they were kept inflated (at 200 mmHg) for two minutes. The resulting transient changes in cerebral oxy- (O) and deoxy- (D) hemoglobin concentrations measured with NIRS on the prefrontal cortex are then described by a novel hemodynamic model, from which quantifiable parameters such as the capillary blood transit time and a cutoff frequency for cerebral autoregulation are obtained. We present results on eleven healthy volunteers in a protocol involving measurements during normal breathing and during hyperventilation, which is known to cause a hypocapnia-induced increase in cerebral autoregulation. The measured capillary transit time was unaffected by hyperventilation (normal breathing: 1.1±0.1 s; hyperventilation: 1.1±0.1 s), whereas the cutoff frequency of autoregulation, which increases for higher autoregulation efficiency, was indeed found to be significantly greater during hyperventilation (normal breathing: 0.017±0.002 Hz; hyperventilation: 0.034±0.005 Hz). These results provide a validation of local cerebral autoregulation measurements with the new technique of CHS.

  18. Real time method and computer system for identifying radioactive materials from HPGe gamma-ray spectroscopy

    DOEpatents

    Rowland, Mark S.; Howard, Douglas E.; Wong, James L.; Jessup, James L.; Bianchini, Greg M.; Miller, Wayne O.

    2007-10-23

    A real-time method and computer system for identifying radioactive materials which collects gamma count rates from a HPGe gamma-radiation detector to produce a high-resolution gamma-ray energy spectrum. A library of nuclear material definitions ("library definitions") is provided, with each uniquely associated with a nuclide or isotope material and each comprising at least one logic condition associated with a spectral parameter of a gamma-ray energy spectrum. The method determines whether the spectral parameters of said high-resolution gamma-ray energy spectrum satisfy all the logic conditions of any one of the library definitions, and subsequently uniquely identifies the material type as that nuclide or isotope material associated with the satisfied library definition. The method is iteratively repeated to update the spectrum and identification in real time.

  19. In vivo gamma-aminobutyric acid and glutamate levels in people with first-episode schizophrenia: A proton magnetic resonance spectroscopy study.

    PubMed

    Chiu, P W; Lui, Simon S Y; Hung, Karen S Y; Chan, Raymond C K; Chan, Queenie; Sham, P C; Cheung, Eric F C; Mak, Henry K F

    2018-03-01

    Gamma-aminobutyric acid (GABA) dysfunction and its consequent imbalance are implicated in the pathophysiology of schizophrenia. Reduced GABA production would lead to a disinhibition of glutamatergic neurons and subsequently cause a disruption of the modulation between GABAergic interneurons and glutamatergic neurons. In this study, levels of GABA, Glx (summation of glutamate and glutamine), and other metabolites in the anterior cingulate cortex were measured and compared between first-episode schizophrenia subjects and healthy controls (HC). Diagnostic potential of GABA and Glx as upstream biomarkers for schizophrenia was explored. Nineteen first-episode schizophrenia subjects and fourteen HC participated in this study. Severity of clinical symptoms of patients was measured with Positive and Negative Syndrome Scale (PANSS). Metabolites were measured using proton magnetic resonance spectroscopy, and quantified using internal water as reference. First-episode schizophrenia subjects revealed reduced GABA and myo-inositol (mI), and increased Glx and choline (Cho), compared to HC. No significant correlation was found between metabolite levels and PANSS scores. Receiver operator characteristics analyses showed Glx had higher sensitivity and specificity (84.2%, 92.9%) compared to GABA (73.7%, 64.3%) for differentiating schizophrenia patients from HC. Combined model of both GABA and Glx revealed the best sensitivity and specificity (89.5%, 100%). This study simultaneously showed reduction in GABA and elevation in Glx in first-episode schizophrenia subjects, and this might provide insights on explaining the disruption of modulation between GABAergic interneurons and glutamatergic neurons. Elevated Cho might indicate increased membrane turnover; whereas reduced mI might reflect dysfunction of the signal transduction pathway. In vivo Glx and GABA revealed their diagnostic potential for schizophrenia. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. A method to describe inelastic gamma field distribution in neutron gamma density logging.

    PubMed

    Zhang, Feng; Zhang, Quanying; Liu, Juntao; Wang, Xinguang; Wu, He; Jia, Wenbao; Ti, Yongzhou; Qiu, Fei; Zhang, Xiaoyang

    2017-11-01

    Pulsed neutron gamma density logging (NGD) is of great significance for radioprotection and density measurement in LWD, however, the current methods have difficulty in quantitative calculation and single factor analysis for the inelastic gamma field distribution. In order to clarify the NGD mechanism, a new method is developed to describe the inelastic gamma field distribution. Based on the fast-neutron scattering and gamma attenuation, the inelastic gamma field distribution is characterized by the inelastic scattering cross section, fast-neutron scattering free path, formation density and other parameters. And the contribution of formation parameters on the field distribution is quantitatively analyzed. The results shows the contribution of density attenuation is opposite to that of inelastic scattering cross section and fast-neutron scattering free path. And as the detector-spacing increases, the density attenuation gradually plays a dominant role in the gamma field distribution, which means large detector-spacing is more favorable for the density measurement. Besides, the relationship of density sensitivity and detector spacing was studied according to this gamma field distribution, therefore, the spacing of near and far gamma ray detector is determined. The research provides theoretical guidance for the tool parameter design and density determination of pulsed neutron gamma density logging technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Statistical Measurement of the Gamma-Ray Source-count Distribution as a Function of Energy

    NASA Astrophysics Data System (ADS)

    Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza; Fornengo, Nicolao; Regis, Marco

    2016-08-01

    Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. We employ the 1-point probability distribution function of six years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy. To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 and 171 GeV. It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of ˜50 GeV. The index below the break is between 1.95 and 2.0. For higher energies, a simple power-law fits the data, with an index of {2.2}-0.3+0.7 in the energy band between 50 and 171 GeV. Upper limits on further possible breaks as well as the angular power of unresolved sources are derived. We find that point-source populations probed by this method can explain {83}-13+7% ({81}-19+52%) of the extragalactic gamma-ray background between 1.04 and 1.99 GeV (50 and 171 GeV). The method has excellent capabilities for constraining the gamma-ray luminosity function and the spectra of unresolved blazars.

  2. Investigating the anisotropic scintillation response in anthracene through neutron, gamma-ray, and muon measurements

    DOE PAGES

    Schuster, Patricia; Brubaker, Erik

    2016-05-05

    Our paper reports a series of measurements that characterize the directional dependence of the scintillation response of crystalline anthracene to incident DT neutrons, DD neutrons, 137Cs gamma rays, and, for the first time, cosmic ray muons. Moreover, the neutron measurements give the amplitude and pulse shape dependence on the proton recoil direction over one hemisphere of the crystal, confirming and extending previous results in the literature. In similar measurements using incident gamma rays, no directional effect is evident, and any anisotropy with respect to the electron recoil direction is constrained to have a magnitude of less than a tenth ofmore » that present in the proton recoil events. Cosmic muons are measured at two directions, and no anisotropy is observed. Our set of observations indicates that high dE/dx is necessary for an anisotropy to be present for a given type of scintillation event, which in turn could be used to discriminate among different hypotheses for the underlying causes of the anisotropy, which are not well understood.« less

  3. Voxel-based measurement sensitivity of spatially resolved near-infrared spectroscopy in layered tissues

    NASA Astrophysics Data System (ADS)

    Niwayama, Masatsugu

    2018-03-01

    We quantitatively investigated the measurement sensitivity of spatially resolved spectroscopy (SRS) across six tissue models: cerebral tissue, a small animal brain, the forehead of a fetus, an adult brain, forearm muscle, and thigh muscle. The optical path length in the voxel of the model was analyzed using Monte Carlo simulations. It was found that the measurement sensitivity can be represented as the product of the change in the absorption coefficient and the difference in optical path length in two states with different source-detector distances. The results clarified the sensitivity ratio between the surface layer and the deep layer at each source-detector distance for each model and identified changes in the deep measurement area when one of the detectors was close to the light source. A comparison was made with the results from continuous-wave spectroscopy. The study also identified measurement challenges that arise when the surface layer is inhomogeneous. Findings on the measurement sensitivity of SRS at each voxel and in each layer can support the correct interpretation of measured values when near-infrared oximetry or functional near-infrared spectroscopy is used to investigate different tissue structures.

  4. Measurement of Environmental NO2 by Photoacoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Gaoxuan; Yi, Hongming; Fertein, Eric; Sigrist, Markus W.; Chen, Weidong

    2016-04-01

    The most widely used technique for the measurements of nitrogen dioxide (NO2) is the chemiluminescence technique. However this indirect NO2 measurement method is affected by positive or negative interferences due to the use of non selective catalyzer molybdenum or photolytic converter [1]. Photoacoustic spectroscopy (PAS) offers the capability of interference-free direct NO2 measurement without any sample preparation or/and chemical conversion [2,3]. In this paper, we report on the development and applications of a photoacoustic spectroscopy-based NO2 sensor for continuous measurement of NO2 in air with a sensitivity of about 0.5 ppb (SNR=1) and 1 min time resolution. Time series measurements of environmental NO2 concentrations were carried out and compared with side-by-side measurements by a NOx analyzer (AC-31 M). Good agreement has been observed. Experimental detail and preliminary results will be presented. Acknowledgements The authors acknowledge financial supports from the CaPPA project (ANR-10-LABX-005) and the CPER CLIMIBIO program. G. W. thanks the "Pôle Métropolitain de la Côte d'Opale" (PMCO) and the Région Nord Pas de Calais for the PhD fellowship support. References [1] G. Villena, I. Bejan, R. Kurtenbach, P. Wiesen, J. Kleffmann, "Interferences of Commercial NO2 instruments in the urban atmosphere and in a smog chamber", Atmos. Meas. Tech. 5 (2012) 149. [2] M. Lassen, D. B. Clsusen, A. Brusch, J. C. Petersen, "A versatil integrating sphere based photoacoustic sensor for trace gas monitoring", Opt. Express 22 (2014) 11660. [3] C. Haisch, R. Niessner, "Photoacoustic analyzer for the artifact-free parallel detection of soot and NO2 in engin exhaut", Anal. Chem. 84 (2012) 7292.

  5. Sample preparation for the determination of 241Am in sediments utilizing gamma-spectroscopy.

    PubMed

    Ristic, M; Degetto, S; Ast, T; Cantallupi, C

    2002-01-01

    This paper describes a procedure developed to separate americium-241 from the bulk of a sample by coprecipitation followed by high sensitivity gamma-counting of the concentrate in a well-type detector. It enables the measurement of 241Am at low concentrations, e.g. fallout levels in soils and sediments, or where large sample sizes are not available. The method is much faster and more reliable than those involving separation from other alpha-emitters, electroplating and alpha-spectrometry. A number of tracer experiments was performed in order to optimize the conditions for coprecipitation of 241Am from sediment leachates. The general outline of the determination of americium is also given.

  6. High-gamma band fronto-temporal coherence as a measure of functional connectivity in speech motor control.

    PubMed

    Kingyon, J; Behroozmand, R; Kelley, R; Oya, H; Kawasaki, H; Narayanan, N S; Greenlee, J D W

    2015-10-01

    The neural basis of human speech is unclear. Intracranial electrophysiological recordings have revealed that high-gamma band oscillations (70-150Hz) are observed in the frontal lobe during speech production and in the temporal lobe during speech perception. Here, we tested the hypothesis that the frontal and temporal brain regions had high-gamma coherence during speech. We recorded electrocorticography (ECoG) from the frontal and temporal cortices of five humans who underwent surgery for medically intractable epilepsy, and studied coherence between the frontal and temporal cortex during vocalization and playback of vocalization. We report two novel results. First, we observed high-gamma band as well as theta (4-8Hz) coherence between frontal and temporal lobes. Second, both high-gamma and theta coherence were stronger when subjects were actively vocalizing as compared to playback of the same vocalizations. These findings provide evidence that coupling between sensory-motor networks measured by high-gamma coherence plays a key role in feedback-based monitoring and control of vocal output for human vocalization. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  7. On the accuracy of gamma spectrometric isotope ratio measurements of uranium

    NASA Astrophysics Data System (ADS)

    Ramebäck, H.; Lagerkvist, P.; Holmgren, S.; Jonsson, S.; Sandström, B.; Tovedal, A.; Vesterlund, A.; Vidmar, T.; Kastlander, J.

    2016-04-01

    The isotopic composition of uranium was measured using high resolution gamma spectrometry. Two acid solutions and two samples in the form of UO2 pellets were measured. The measurements were done in close geometries, i.e. directly on the endcap of the high purity germanium detector (HPGe). Applying no corrections for count losses due to true coincidence summing (TCS) resulted in up to about 40% deviation in the abundance of 235U from the results obtained with mass spectrometry. However, after correction for TCS, excellent agreement was achieved between the results obtained using two different measurement methods, or a certified value. Moreover, after corrections, the fitted relative response curves correlated excellently with simulated responses, for the different geometries, of the HPGe detector.

  8. {gamma}-ray spectroscopy study of states in {sup 27}Si relevant for the {sup 26}Al{sup m}(p,{gamma}){sup 27}Si reaction in novae and supernovae

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lotay, G.; Woods, P. J.; Seweryniak, D.

    2009-11-15

    The heavy-ion, fusion-evaporation reaction {sup 12}C({sup 16}O,n) was used to identify {gamma}-decay transitions from excited states in {sup 27}Si above the proton threshold. The precise level energy measurements, J{sup {pi}} assignments, and lifetime measurements of astrophysically important {sup 26}Al{sup m}+p resonances have allowed an evaluation of the {sup 26}Al{sup m}(p,{gamma}){sup 27}Si reaction rate. An l{sub p}=0 resonance has been newly identified at a center-of-mass energy in the {sup 26}Al{sup m}+p system of 146.3(3) keV and is expected to dominate the rate for low stellar temperatures. In addition, an l{sub p}=1 resonance has been identified at 378.3(30) keV and is likelymore » to dominate the rate at high astrophysical temperatures, such as those found in oxygen-neon novae and core-collapse supernovae.« less

  9. Analyzing Space-Based Interferometric Measurements of Stars and Network Measurements of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Taff, L. G.

    1998-01-01

    Since the announcement of the discovery of sources of bursts of gamma-ray radiation in 1973, hundreds more reports of such bursts have now been published. Numerous artificial satellites have been equipped with gamma-ray detectors including the very successful Compton Gamma Ray Observatory BATSE instrument. Unfortunately, we have made no progress in identifying the source(s) of this high energy radiation. We suspected that this was a consequence of the method used to define gamma-ray burst source "error boxes." An alternative procedure to compute gamma-ray burst source positions, with a purely physical underpinning, was proposed in 1988 by Taff. Since then we have also made significant progress in understanding the analytical nature of the triangulation problem and in computing actual gamma-ray burst positions and their corresponding error boxes. For the former, we can now mathematically illustrate the crucial role of the area occupied by the detectors, while for the latter, the Atteia et al. (1987) catalog has been completely re-reduced. There are very few discrepancies in locations between our results and those of the customary "time difference of arrival" procedure. Thus, we have numerically demonstrated that the end result, for the positions, of these two very different-looking procedures is the same. Finally, for the first time, we provide a sample of realistic "error boxes" whose non-simple shapes vividly portray the difficulty of burst source localization.

  10. Gamma Spectroscopy by Artificial Neural Network Coupled with MCNP

    NASA Astrophysics Data System (ADS)

    Sahiner, Huseyin

    While neutron activation analysis is widely used in many areas, sensitivity of the analysis depends on how the analysis is conducted. Even though the sensitivity of the techniques carries error, compared to chemical analysis, its range is in parts per million or sometimes billion. Due to this sensitivity, the use of neutron activation analysis becomes important when analyzing bio-samples. Artificial neural network is an attractive technique for complex systems. Although there are neural network applications on spectral analysis, training by simulated data to analyze experimental data has not been made. This study offers an improvement on spectral analysis and optimization on neural network for the purpose. The work considers five elements that are considered as trace elements for bio-samples. However, the system is not limited to five elements. The only limitation of the study comes from data library availability on MCNP. A perceptron network was employed to identify five elements from gamma spectra. In quantitative analysis, better results were obtained when the neural fitting tool in MATLAB was used. As a training function, Levenberg-Marquardt algorithm was used with 23 neurons in the hidden layer with 259 gamma spectra in the input. Because the interest of the study deals with five elements, five neurons representing peak counts of five isotopes in the input layer were used. Five output neurons revealed mass information of these elements from irradiated kidney stones. Results showing max error of 17.9% in APA, 24.9% in UA, 28.2% in COM, 27.9% in STRU type showed the success of neural network approach in analyzing gamma spectra. This high error was attributed to Zn that has a very long decay half-life compared to the other elements. The simulation and experiments were made under certain experimental setup (3 hours irradiation, 96 hours decay time, 8 hours counting time). Nevertheless, the approach is subject to be generalized for different setups.

  11. Mass measurement of 80Y by β-γ coincidence spectroscopy

    NASA Astrophysics Data System (ADS)

    Barton, C. J.; Brenner, D. S.; Zamfir, N. V.; Caprio, M. A.; Aprahamian, A.; Wiescher, M. C.; Beausang, C. W.; Berant, Z.; Casten, R. F.; Cooper, J. R.; Gill, R. L.; Krücken, R.; Novak, J. R.; Pietralla, N.; Shawcross, M.; Teymurazyan, A.; Wolf, A.

    2003-03-01

    The QEC value of 80Y has been measured by β-γ coincidence spectroscopy to be ⩾8929(83) keV. Combining this result with the adopted mass excess of the daughter 80Sr gives a mass excess for 80Y of ⩾-61 376(83) keV. Results are compared with other measurements, with Audi-Wapstra systematics, and with predictions of mass formulas. Implications of this measurement are considered for the rp process.

  12. EPR Investigation of Gamma-Irradiated Rapana Thomasiana (Gastropoda, Muricidae) Shell

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Seletchi, Emilia Dana; Duliu, Octavian G.; Georgescu, Rodica

    2007-04-23

    The shell of Rapana Thomasiana snail, a carnivorous gastropod collected from the coasts of the Black Sea (Romania) was investigated by using Electron Paramagnetic Resonance (EPR) spectroscopy. The samples in powder form were irradiated with a 60Co gamma-ray source at ambient temperature in the dose range between 1.06 and 11.3 kGy. The measurements showed that the EPR signal intensity enhanced following saturation exponential with the absorbed dose. The estimated EPR parameters: g1 = 1.9976, g2 = 2.0006, g3 = 2.0015, g4 = 2.0030 and g5 = 2.0043 revealed a complex spectrum consisting of CO{sub 2}{sup -}, CO{sub 3}{sup 3-} andmore » CO{sub 3}{sup -} species. A very weak signal at g6 = 2.0057 was associated to SO{sub 2}{sup -} electron center. All EPR signals of gamma-irradiated samples decreased with various rate with the of 100 deg. C isothermal annealing time.« less

  13. A method to measure neutron polarization using P-even asymmetry of {gamma}-quantum emission in the neutron-nuclear interaction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gledenov, Yu. M.; Nesvizhevsky, V. V.; Sedyshev, P. V.

    2012-07-15

    A new method to measure polarization of cold/thermal neutrons using P-even asymmetry in nuclear reactions induced by polarized neutrons is proposed. A scheme profiting from a large correlation of the neutron spin and the circular {gamma}-quantum polarization in the reaction (n, {gamma}) of polarized neutrons with nuclei is analyzed. This method could be used, for instance, to measure the neutron-beam polarization in experiments with frequently varying configuration. We show that high accuracy and reliability of measurements could be expected.

  14. Detection system for high-resolution gamma radiation spectroscopy with neutron time-of-flight filtering

    DOEpatents

    Dioszegi, Istvan; Salwen, Cynthia; Vanier, Peter

    2014-12-30

    A .gamma.-radiation detection system that includes at least one semiconductor detector such as HPGe-Detector, a position-sensitive .alpha.-Detector, a TOF Controller, and a Digitizer/Integrator. The Digitizer/Integrator starts to process the energy signals of a .gamma.-radiation sent from the HPGe-Detector instantly when the HPGe-Detector detects the .gamma.-radiation. Subsequently, it is determined whether a coincidence exists between the .alpha.-particles and .gamma.-radiation signal, based on a determination of the time-of-flight of neutrons obtained from the .alpha.-Detector and the HPGe-Detector. If it is determined that the time-of-flight falls within a predetermined coincidence window, the Digitizer/Integrator is allowed to continue and complete the energy signal processing. If, however, there is no coincidence, the Digitizer/Integrator is instructed to be clear and reset its operation instantly.

  15. Field spectroscopy sampling strategies for improved measurement of Earth surface reflectance

    NASA Astrophysics Data System (ADS)

    Mac Arthur, A.; Alonso, L.; Malthus, T. J.; Moreno, J. F.

    2013-12-01

    Over the last two decades extensive networks of research sites have been established to measure the flux of carbon compounds and water vapour between the Earth's surface and the atmosphere using eddy covariance (EC) techniques. However, contributing Earth surface components cannot be determined and (as the ';footprints' are spatially constrained) these measurements cannot be extrapolated to regional cover using this technique. At many of these EC sites researchers have been integrating spectral measurements with EC and ancillary data to better understand light use efficiency and carbon dioxide flux. These spectroscopic measurements could also be used to assess contributing components and provide support for imaging spectroscopy, from airborne or satellite platforms, which can provide unconstrained spatial cover. Furthermore, there is an increasing interest in ';smart' database and information retrieval systems such as that proposed by EcoSIS and OPTIMISE to store, analyse, QA and merge spectral and biophysical measurements and provide information to end users. However, as Earth surfaces are spectrally heterogeneous and imaging and field spectrometers sample different spatial extents appropriate field sampling strategies require to be adopted. To sample Earth surfaces spectroscopists adopt either single; random; regular grid; transect; or 'swiping' point sampling strategies, although little comparative work has been carried out to determine the most appropriate approach; the work by Goetz (2012) is a limited exception. Mac Arthur et al (2012) demonstrated that, for two full wavelength (400 nm to 2,500 nm) field spectroradiometers, the measurement area sampled is defined by each spectroradiometer/fore optic system's directional response function (DRF) rather than the field-of-view (FOV) specified by instrument manufacturers. Mac Arthur et al (2012) also demonstrated that each reflecting element within the sampled area was not weighted equally in the integrated

  16. 137 Ba Double Gamma Decay Measurement with GAMMASPHERE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Merchán, E.; Moran, K.; Lister, C. J.

    2015-05-28

    The study of the electromagnetic moments (EM), and decay probability, provides detailed information about nuclear wave functions. The well-know properties of EM interactions are good for extracting information about the motion of nucleons. Higher order EM processes always occur, but are usually too weak to be measured. In the case of a 0 + → 0 + transitions, where a single gamma transition is forbidden, the simultaneous emission of two γ-rays has been studied. An interesting opportunity to further investigate 2-photon emission phenomena is by using a standard 137Cs source populating, via β-decay, the J π = 11/2 - isomericmore » state at 662 keV in 137Ba. In this case, two photon process can have contributions from quadrupole-quadrupole or dipole-octupole multipolarities in direct competition with the high multipolarity M4 decay. Since the yield of the double gamma decay is around six orders of magnitude less than the first order transition, very good statistics are needed in order to observe the phenomena and great care must be taken to suppress the first-order decay. The Gammasphere array is ideal since its configuration allows a good coverage of the angular distribution and the Compton events can be suppressed. Nevertheless the process to understand and eliminate the Compton background is a challenge. Geant4 simulations were carried out to help understand and correct for those factors.« less

  17. Enhanced Analysis Techniques for an Imaging Neutron and Gamma Ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Madden, Amanda C.

    The presence of gamma rays and neutrons is a strong indicator of the presence of Special Nuclear Material (SNM). The imaging Neutron and gamma ray SPECTrometer (NSPECT) developed by the University of New Hampshire and Michigan Aerospace corporation detects the fast neutrons and prompt gamma rays from fissile material, and the gamma rays from radioactive material. The instrument operates as a double scatter device, requiring a neutron or a gamma ray to interact twice in the instrument. While this detection requirement decreases the efficiency of the instrument, it offers superior background rejection and the ability to measure the energy and momentum of the incident particle. These measurements create energy spectra and images of the emitting source for source identification and localization. The dual species instrument provides superior detection than a single species alone. In realistic detection scenarios, few particles are detected from a potential threat due to source shielding, detection at a distance, high background, and weak sources. This contributes to a small signal to noise ratio, and threat detection becomes difficult. To address these difficulties, several enhanced data analysis tools were developed. A Receiver Operating Characteristic Curve (ROC) helps set instrumental alarm thresholds as well as to identify the presence of a source. Analysis of a dual-species ROC curve provides superior detection capabilities. Bayesian analysis helps to detect and identify the presence of a source through model comparisons, and helps create a background corrected count spectra for enhanced spectroscopy. Development of an instrument response using simulations and numerical analyses will help perform spectra and image deconvolution. This thesis will outline the principles of operation of the NSPECT instrument using the double scatter technology, traditional analysis techniques, and enhanced analysis techniques as applied to data from the NSPECT instrument, and an

  18. The performance of the γ-ray tracking array GRETINA for γ-ray spectroscopy with fast beams of rare isotopes

    DOE PAGES

    Weisshaar, D.; Bazin, D.; Bender, P. C.; ...

    2016-12-03

    The gamma-ray tracking array GRETINA was coupled to the S800 magnetic spectrometer for spectroscopy with fast beams of rare isotopes at the National Superconducting Cyclotron Laboratory on the campus of Michigan State University. We describe the technical details of this powerful setup and report on GRETINA's performance achieved with source and in-beam measurements. The gamma-ray multiplicity encountered in experiments with fast beams is usually low, allowing for a simplified and efficient treatment of the data in the gamma-ray analysis in terms of Doppler reconstruction and spectral quality. Finally, the results reported in this work were obtained from GRETINA consisting ofmore » 8 detector modules hosting four high-purity germanium crystals each. Currently, GRETINA consists of 10 detector modules.« less

  19. Impact of gamma radiation on the eruption rate of rat incisors

    NASA Astrophysics Data System (ADS)

    El-Faramawy, Nabil; El-Haddad, Khaled; Ali, Mohamed; Talaat, Mona

    2015-09-01

    The present work aims to test the effect of gamma radiation on the rate of eruption of rat incisors. One hundred and five adult male albino rats were used and irradiated at different gamma doses. The effects of irradiation were investigated by numerical measurements of eruption rate, histological investigation using light microscope and spectral analysis using Fourier Transform Infra-Red (FTIR). No detectable changes were observed in the groups with smaller radiation doses. There was a significant decrease in the eruption rate starting from the 4 Gy radiation dose. The observation of histological sections revealed disturbance in cellular elements responsible for eruption as well as periodontal disturbance in the samples irradiated with 4 and 6 Gy. FTIR Spectroscopy of control group and the group irradiated by 0.5 Gy showed similar absorption bands with minor differences. However, samples irradiated by 1 Gy showed significant changes in both molecular structure and conformation related to carbonates and hydroxyl groups. From the previous results, it could be concluded that gamma irradiation negatively affects the eruption rate of the rat incisors especially with higher doses.

  20. Measurement of sulfur isotope compositions by tunable laser spectroscopy of SO2.

    PubMed

    Christensen, Lance E; Brunner, Benjamin; Truong, Kasey N; Mielke, Randall E; Webster, Christopher R; Coleman, Max

    2007-12-15

    Sulfur isotope measurements offer comprehensive information on the origin and history of natural materials. Tunable laser spectroscopy is a powerful analytical technique for isotope analysis that has proven itself readily adaptable for in situ terrestrial and planetary measurements. Measurements of delta(34)S in SO2 were made using tunable laser spectroscopy of combusted gas samples from six sulfur-bearing solids with delta(34)S ranging from -34 to +22 per thousand (also measured with mass spectrometry). Standard deviation between laser and mass spectrometer measurements was 3.7 per thousand for sample sizes of 200 +/- 75 nmol SO(2). Although SO(2)(g) decreased 9% over 15 min upon entrainment in the analysis cell from wall uptake, observed fractionation was insignificant (+0.2 +/- 0.6 per thousand). We also describe a strong, distinct (33)SO(2) rovibrational transition in the same spectral region, which may enable simultaneous delta(34)S and Delta(33)S measurements.

  1. EFFECTS OF GAMMA IRRADIATION ON EPDM ELASTOMERS (REVISION 1)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Clark, E.

    Two formulations of EPDM elastomer, one substituting a UV stabilizer for the normal antioxidant in this polymer, and the other the normal formulation, were synthesized and samples of each were exposed to gamma irradiation in initially pure deuterium gas to compare their radiation stability. Stainless steel containers having rupture disks were designed for this task. After 130 MRad dose of cobalt-60 radiation in the SRNL Gamma Irradiation Facility, a significant amount of gas was created by radiolysis; however the composition indicated by mass spectroscopy indicated an unexpected increase in the total amount deuterium in both formulations. The irradiated samples retainedmore » their ductility in a bend test. No change of sample weight, dimensions, or density was observed. No change of the glass transition temperature as measured by dynamic mechanical analysis was observed, and most of the other dynamic mechanical properties remained unchanged. There appeared to be an increase in the storage modulus of the irradiated samples containing the UV stabilizer above the glass transition, which may indicate hardening of the material by radiation damage. Revision 1 adds a comparison with results of a study of tritium exposed EPDM. The amount of gas produced by the gamma irradiation was found to be equivalent to about 280 days exposure to initially pure tritium gas at one atmosphere. The glass transition temperature of the tritium exposed EPDM rose about 10°C. over 280 days, while no glass transition temperature change was observed for gamma irradiated EPDM. This means that gamma irradiation in deuterium cannot be used as a surrogate for tritium exposure.« less

  2. Precision Spectroscopy, Diode Lasers, and Optical Frequency Measurement Technology

    NASA Technical Reports Server (NTRS)

    Hollberg, Leo (Editor); Fox, Richard (Editor); Waltman, Steve (Editor); Robinson, Hugh

    1998-01-01

    This compilation is a selected set of reprints from the Optical Frequency Measurement Group of the Time and Frequency Division of the National Institute of Standards and Technology, and consists of work published between 1987 and 1997. The two main programs represented here are (1) development of tunable diode-laser technology for scientific applications and precision measurements, and (2) research toward the goal of realizing optical-frequency measurements and synthesis. The papers are organized chronologically in five, somewhat arbitrarily chosen categories: Diode Laser Technology, Tunable Laser Systems, Laser Spectroscopy, Optical Synthesis and Extended Wavelength Coverage, and Multi-Photon Interactions and Optical Coherences.

  3. Measurement of Radon in Indoor Air.

    ERIC Educational Resources Information Center

    Downey, Daniel M.; Simolunas, Glenn

    1988-01-01

    Describes a laboratory experiment to teach the principles of air sampling, gamma ray spectroscopy, nuclear decay, and radioactive equilibrium. Analyzes radon by carbon adsorption and gamma ray counting. Provides methodology and rate of decay equations. (MVL)

  4. Measuring Rocket Engine Temperatures with Hydrogen Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Wehrmeyer, Joseph A.; Osborne, Robin J.; Trinh, Huu P.; Turner, James (Technical Monitor)

    2001-01-01

    Optically accessible, high pressure, hot fire test articles are available at NASA Marshall for use in development of advanced rocket engine propellant injectors. Single laser-pulse ultraviolet (UV) Raman spectroscopy has been used in the past in these devices for analysis of high pressure H2- and CH4-fueled combustion, but relies on an independent pressure measurement in order to provide temperature information. A variation of UV Raman (High Resolution Hydrogen Raman Spectroscopy) is under development and will allow temperature measurement without the need for an independent pressure measurement, useful for flows where local pressure may not be accurately known. The technique involves the use of a spectrometer with good spectral resolution, requiring a small entrance slit for the spectrometer. The H2 Raman spectrum, when created by a narrow linewidth laser source and obtained from a good spectral resolution spectrograph, has a spectral shape related to temperature. By best-fit matching an experimental spectrum to theoretical spectra at various temperatures, a temperature measurement is obtained. The spectral model accounts for collisional narrowing, collisional broadening, Doppler broadening, and collisional line shifting of each Raman line making up the H2 Stokes vibrational Q-branch spectrum. At pressures from atmospheric up to those associated with advanced preburner components (5500 psia), collisional broadening though present does not cause significant overlap of the Raman lines, allowing high resolution H2 Raman to be used for temperature measurements in plumes and in high pressure test articles. Experimental demonstrations of the technique are performed for rich H2-air flames at atmospheric pressure and for high pressure, 300 K H2-He mixtures. Spectrometer imaging quality is identified as being critical for successful implementation of technique.

  5. Statistical measurement of the gamma-ray source-count distribution as a function of energy

    DOE PAGES

    Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza; ...

    2016-07-29

    Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. Here, we employ the 1-point probability distribution function of six years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy. To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 and 171 GeV. It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of ~50 GeV. Furthermore, the index below the break is between 1.95 and 2.0. For higher energies, a simple power-law fits the data, with an index ofmore » $${2.2}_{-0.3}^{+0.7}$$ in the energy band between 50 and 171 GeV. Upper limits on further possible breaks as well as the angular power of unresolved sources are derived. We find that point-source populations probed by this method can explain $${83}_{-13}^{+7}$$% ($${81}_{-19}^{+52}$$%) of the extragalactic gamma-ray background between 1.04 and 1.99 GeV (50 and 171 GeV). Our method has excellent capabilities for constraining the gamma-ray luminosity function and the spectra of unresolved blazars.« less

  6. Statistical measurement of the gamma-ray source-count distribution as a function of energy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza

    Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. Here, we employ the 1-point probability distribution function of six years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy. To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 and 171 GeV. It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of ~50 GeV. Furthermore, the index below the break is between 1.95 and 2.0. For higher energies, a simple power-law fits the data, with an index ofmore » $${2.2}_{-0.3}^{+0.7}$$ in the energy band between 50 and 171 GeV. Upper limits on further possible breaks as well as the angular power of unresolved sources are derived. We find that point-source populations probed by this method can explain $${83}_{-13}^{+7}$$% ($${81}_{-19}^{+52}$$%) of the extragalactic gamma-ray background between 1.04 and 1.99 GeV (50 and 171 GeV). Our method has excellent capabilities for constraining the gamma-ray luminosity function and the spectra of unresolved blazars.« less

  7. PARTICULATE MATTER MEASUREMENTS USING OPEN-PATH FOURIER TRANSFORM INFRARED SPECTROSCOPY

    EPA Science Inventory

    Open-path Fourier transform infrared (OP-FT1R) spectroscopy is an accepted technology for measuring gaseous air contaminants. OP-FT1R absorbance spectra acquired during changing aerosols conditions reveal related changes in very broad baseline features. Usually, this shearing of ...

  8. Method of incident low-energy gamma-ray direction reconstruction in the GAMMA-400 gamma-ray space telescope

    NASA Astrophysics Data System (ADS)

    Kheymits, M. D.; Leonov, A. A.; Zverev, V. G.; Galper, A. M.; Arkhangelskaya, I. V.; Arkhangelskiy, A. I.; Suchkov, S. I.; Topchiev, N. P.; Yurkin, Yu T.; Bakaldin, A. V.; Dalkarov, O. D.

    2016-02-01

    The GAMMA-400 gamma-ray space-based telescope has as its main goals to measure cosmic γ-ray fluxes and the electron-positron cosmic-ray component produced, theoretically, in dark-matter-particles decay or annihilation processes, to search for discrete γ-ray sources and study them in detail, to examine the energy spectra of diffuse γ-rays — both galactic and extragalactic — and to study gamma-ray bursts (GRBs) and γ-rays from the active Sun. Scientific goals of GAMMA-400 telescope require fine angular resolution. The telescope is of a pair-production type. In the converter-tracker, the incident gamma-ray photon converts into electron-positron pair in the tungsten layer and then the tracks are detected by silicon- strip position-sensitive detectors. Multiple scattering processes become a significant obstacle in the incident-gamma direction reconstruction for energies below several gigaelectronvolts. The method of utilising this process to improve the resolution is proposed in the presented work.

  9. Neutron monitoring systems including gamma thermometers and methods of calibrating nuclear instruments using gamma thermometers

    DOEpatents

    Moen, Stephan Craig; Meyers, Craig Glenn; Petzen, John Alexander; Foard, Adam Muhling

    2012-08-07

    A method of calibrating a nuclear instrument using a gamma thermometer may include: measuring, in the instrument, local neutron flux; generating, from the instrument, a first signal proportional to the neutron flux; measuring, in the gamma thermometer, local gamma flux; generating, from the gamma thermometer, a second signal proportional to the gamma flux; compensating the second signal; and calibrating a gain of the instrument based on the compensated second signal. Compensating the second signal may include: calculating selected yield fractions for specific groups of delayed gamma sources; calculating time constants for the specific groups; calculating a third signal that corresponds to delayed local gamma flux based on the selected yield fractions and time constants; and calculating the compensated second signal by subtracting the third signal from the second signal. The specific groups may have decay time constants greater than 5.times.10.sup.-1 seconds and less than 5.times.10.sup.5 seconds.

  10. Indoor radon measurements in south west England explained by topsoil and stream sediment geochemistry, airborne gamma-ray spectroscopy and geology.

    PubMed

    Ferreira, Antonio; Daraktchieva, Zornitza; Beamish, David; Kirkwood, Charles; Lister, T Robert; Cave, Mark; Wragg, Joanna; Lee, Kathryn

    2018-01-01

    Predictive mapping of indoor radon potential often requires the use of additional datasets. A range of geological, geochemical and geophysical data may be considered, either individually or in combination. The present work is an evaluation of how much of the indoor radon variation in south west England can be explained by four different datasets: a) the geology (G), b) the airborne gamma-ray spectroscopy (AGR), c) the geochemistry of topsoil (TSG) and d) the geochemistry of stream sediments (SSG). The study area was chosen since it provides a large (197,464) indoor radon dataset in association with the above information. Geology provides information on the distribution of the materials that may contribute to radon release while the latter three items provide more direct observations on the distributions of the radionuclide elements uranium (U), thorium (Th) and potassium (K). In addition, (c) and (d) provide multi-element assessments of geochemistry which are also included in this study. The effectiveness of datasets for predicting the existing indoor radon data is assessed through the level (the higher the better) of explained variation (% of variance or ANOVA) obtained from the tested models. A multiple linear regression using a compositional data (CODA) approach is carried out to obtain the required measure of determination for each analysis. Results show that, amongst the four tested datasets, the soil geochemistry (TSG, i.e. including all the available 41 elements, 10 major - Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Ti - plus 31 trace) provides the highest explained variation of indoor radon (about 40%); more than double the value provided by U alone (ca. 15%), or the sub composition U, Th, K (ca. 16%) from the same TSG data. The remaining three datasets provide values ranging from about 27% to 32.5%. The enhanced prediction of the AGR model relative to the U, Th, K in soils suggests that the AGR signal captures more than just the U, Th and K content in the soil. The

  11. Copper doping of ZnO crystals by transmutation of 64Zn to 65Cu: An electron paramagnetic resonance and gamma spectroscopy study

    NASA Astrophysics Data System (ADS)

    Recker, M. C.; McClory, J. W.; Holston, M. S.; Golden, E. M.; Giles, N. C.; Halliburton, L. E.

    2014-06-01

    Transmutation of 64Zn to 65Cu has been observed in a ZnO crystal irradiated with neutrons. The crystal was characterized with electron paramagnetic resonance (EPR) before and after the irradiation and with gamma spectroscopy after the irradiation. Major features in the gamma spectrum of the neutron-irradiated crystal included the primary 1115.5 keV gamma ray from the 65Zn decay and the positron annihilation peak at 511 keV. Their presence confirmed the successful transmutation of 64Zn nuclei to 65Cu. Additional direct evidence for transmutation was obtained from the EPR of Cu2+ ions (where 63Cu and 65Cu hyperfine lines are easily resolved). A spectrum from isolated Cu2+ (3d9) ions acquired after the neutron irradiation showed only hyperfine lines from 65Cu nuclei. The absence of 63Cu lines in this Cu2+ spectrum left no doubt that the observed 65Cu signals were due to transmuted 65Cu nuclei created as a result of the neutron irradiation. Small concentrations of copper, in the form of Cu+-H complexes, were inadvertently present in our as-grown ZnO crystal. These Cu+-H complexes are not affected by the neutron irradiation, but they dissociate when a crystal is heated to 900 °C. This behavior allowed EPR to distinguish between the copper initially in the crystal and the copper subsequently produced by the neutron irradiation. In addition to transmutation, a second major effect of the neutron irradiation was the formation of zinc and oxygen vacancies by displacement. These vacancies were observed with EPR.

  12. Measuring the activity of a {sup 51}Cr neutrino source based on the gamma-radiation spectrum

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gorbachev, V. V., E-mail: vvgor-gfb1@mail.ru; Gavrin, V. N.; Ibragimova, T. V.

    A technique for the measurement of activities of intense β sources by measuring the continuous gamma-radiation (internal bremsstrahlung) spectra is developed. A method for reconstructing the spectrum recorded by a germanium semiconductor detector is described. A method for the absolute measurement of the internal bremsstrahlung spectrum of {sup 51}Cr is presented.

  13. Study on fast measurement of sugar content of yogurt using Vis/NIR spectroscopy techniques

    NASA Astrophysics Data System (ADS)

    He, Yong; Feng, Shuijuan; Wu, Di; Li, Xiaoli

    2006-09-01

    In order to measuring the sugar content of yogurt rapidly, a fast measurement of sugar content of yogurt using Vis/NIR-spectroscopy techniques was established. 25 samples selected separately from five different brands of yogurt were measured by Vis/NIR-spectroscopy. The sugar content of yogurt on positions scanned by spectrum were measured by a sugar content meter. The mathematical model between sugar content and Vis/NIR spectral measurements was established and developed based on partial least squares (PLS). The correlation coefficient of sugar content based on PLS model is more than 0.894, and standard error of calibration (SEC) is 0.356, standard error of prediction (SEP) is 0.389. Through predicting the sugar content quantitatively of 35 samples of yogurt from 5 different brands, the correlation coefficient between predictive value and measured value of those samples is more than 0.934. The results show the good to excellent prediction performance. The Vis/NIR spectroscopy technique had significantly greater accuracy for determining the sugar content. It was concluded that the Vis/NIRS measurement technique seems reliable to assess the fast measurement of sugar content of yogurt, and a new method for the measurement of sugar content of yogurt was established.

  14. The BATSE experiment on the Gamma Ray Observatory: Solar flare hard x ray and gamma-ray capabilities

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.; Meegan, C. A.; Wilson, R. B.; Parnell, T. A.; Paciesas, W. S.; Pendleton, G. N.; Hudson, H. S.; Matteson, J. L.; Peterson, L. E.; Cline, T. L.

    1989-01-01

    The Burst and Transient Source Experiment (BATSE) for the Gamma Ray Observatory (GRO) consists of eight detector modules that provide full-sky coverage for gamma-ray bursts and other transient phenomena such as solar flares. Each detector module has a thin, large-area scintillation detector (2025 sq cm) for high time-resolution studies, and a thicker spectroscopy detector (125 sq cm) to extend the energy range and provide better spectral resolution. The total energy range of the system is 15 keV to 100 MeV. These 16 detectors and the associated onboard data system should provide unprecedented capabilities for observing rapid spectral changes and gamma-ray lines from solar flares. The presence of a solar flare can be detected in real-time by BATSE; a trigger signal is sent to two other experiments on the GRO. The launch of the GRO is scheduled for June 1990, so that BATSE can be an important component of the Max '91 campaign.

  15. Transcutaneous Measurement of Blood Analyte Concentration Using Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Barman, Ishan; Singh, Gajendra P.; Dasari, Ramachandra R.; Feld, Michael S.

    2008-11-01

    Diabetes mellitus is a chronic disorder, affecting nearly 200 million people worldwide. Acute complications, such as hypoglycemia, cardiovascular disease and retinal damage, may occur if the disease is not adequately controlled. As diabetes has no known cure, tight control of glucose levels is critical for the prevention of such complications. Given the necessity for regular monitoring of blood glucose, development of non-invasive glucose detection devices is essential to improve the quality of life in diabetic patients. The commercially available glucose sensors measure the interstitial fluid glucose by electrochemical detection. However, these sensors have severe limitations, primarily related to their invasive nature and lack of stability. This necessitates the development of a truly non-invasive glucose detection technique. NIR Raman Spectroscopy, which combines the substantial penetration depth of NIR light with the excellent chemical specificity of Raman spectroscopy, provides an excellent tool to meet the challenges involved. Additionally, it enables simultaneous determination of multiple blood analytes. Our laboratory has pioneered the use of Raman spectroscopy for blood analytes' detection in biological media. The preliminary success of our non-invasive glucose measurements both in vitro (such as in serum and blood) and in vivo has provided the foundation for the development of feasible clinical systems. However, successful application of this technology still faces a few hurdles, highlighted by the problems of tissue luminescence and selection of appropriate reference concentration. In this article we explore possible avenues to overcome these challenges so that prospective prediction accuracy of blood analytes can be brought to clinically acceptable levels.

  16. Mass Measurement of 80Y by β-γ Coincidence Spectroscopy

    NASA Astrophysics Data System (ADS)

    Brenner, D. S.; Barton, C. J.; Zamfir, N. V.; Caprio, M. A.; Aprahamian, A.; Beausang, C. W.; Berant, Z.; Casten, R. F.; Cooper, J. R.; Gill, R. L.; Kruecken, R.; Novak, J. R.; Pietralla, N.; Shawcross, M.; Teymurazyan, A.; Wolf, A.; Wiescher, M.

    2003-06-01

    The QEC value of 80Y has been measured by β-γ coincidence spectroscopy to be ≥8929(83) keV. Combing this result with the adopted mass excess of the daughter 80Sr gives a mass excess for 80Y of ≥ -61376(83) keV. Results are compared with other measurements, with Audi-Wapstra systematics, and with predictions of mass formulas. Implications for rp-process simulations are considered.

  17. The U.S. Spectrum X Gamma Coordination Facility

    NASA Astrophysics Data System (ADS)

    Forman, William R.

    1999-08-01

    Spectrum-X-Gamma (SXG) provides for US participation in a first-class international x-ray mission. Despite launch delays, SXG will provide unique scientific opportunities due to its capability for all-sky monitoring, polarimetry, high resolution spectroscopy, and broad wavelength range-from the ultraviolet (TAUVEX and FUVITA), through the x-ray (SODART and JET-X), to the hard x-ray (MART), and gamma-ray burst detectors. Before describing our completed work, we review the unique properties of SXG and provide some examples of the scientific importance of SXG in the Chandra, XMM, and ASTRO-E era.

  18. The U.S. Spectrum X Gamma Coordination Facility

    NASA Technical Reports Server (NTRS)

    Forman, William R.

    1999-01-01

    Spectrum-X-Gamma (SXG) provides for US participation in a first-class international x-ray mission. Despite launch delays, SXG will provide unique scientific opportunities due to its capability for all-sky monitoring, polarimetry, high resolution spectroscopy, and broad wavelength range-from the ultraviolet (TAUVEX and FUVITA), through the x-ray (SODART and JET-X), to the hard x-ray (MART), and gamma-ray burst detectors. Before describing our completed work, we review the unique properties of SXG and provide some examples of the scientific importance of SXG in the Chandra, XMM, and ASTRO-E era.

  19. ELEVATED GAMMA-AMINOBUTYRIC ACID LEVELS IN CHRONIC SCHIZOPHRENIA

    PubMed Central

    Öngür, Dost; Prescot, Andrew P.; McCarthy, Julie; Cohen, Bruce M.; Renshaw, Perry F.

    2010-01-01

    Background Despite widely-replicated abnormalities of gamma-aminobutyric acid (GABA) neurons in schizophrenia postmortem, few studies have measured tissue GABA levels in vivo. We used proton magnetic resonance spectroscopy to measure tissue GABA levels in participants with schizophrenia and healthy controls in the anterior cingulate cortex (ACC) and parieto-occipital cortex (POC). Methods 21 schizophrenia participants effectively treated on a stable medication regimen (mean age 39.0, 14 male) and 19 healthy controls (mean age 36.3, 12 male) underwent a proton magnetic resonance spectroscopy scan using GABA-selective editing at 4 Tesla after providing informed consent. Data were collected from two 16.7cc voxels and analyzed using LCModel. Results We found elevations in GABA/Cr in the schizophrenia group compared with controls (F(1,65)=4.149, p=0.046) in both brain areas (15.5% elevation in ACC, 11.9% in POC). We also found a positive correlation between GABA/Cr and Glu/Cr which was not accounted for by %GM or brain region. Conclusions We found elevated GABA/Cr in participants with chronically treated schizophrenia. Postmortem studies report evidence for dysfunctional GABAergic neurotransmission in schizophrenia. Elevated GABA levels, whether primary to illness or compensatory to another process, may be associated with dysfunctional GABAergic neurotransmission in chronic schizophrenia. PMID:20598290

  20. Fusion gamma diagnostics

    NASA Astrophysics Data System (ADS)

    Medley, S. S.; Cecil, F. E.; Cole, D.; Conway, M. A.; Wilkinson, F. J., III

    1985-05-01

    Nuclear reactions of interest in fusion research often possess a branch yielding prompt emission of gamma radiation in excess of 15 MeV which can be exploited to provide a new fusion reaction diagnostic having applications similar to conventional neutron emission measurements. Conceptual aspects of fusion gamma diagnostics are discussed with emphasis on application to the Tokamak Fusion Test Reactor (TFTR) during deuterium neutral beam heating of D-T and D-3He plasmas. Recent measurements of the D (T, γ)5He, D(3He, γ)5Li, and D(D, γ)4He branching ratios at low center-of-mass energy (30-100 keV) and of the response of a large volume Ne226 detector for gamma detection in high neutron backgrounds are presented. Using a well-shielded Ne226 detector during 20 MW-120 kV deuterium beam heating of a tritium plasma in TFTR, the D(T, γ)5He gamma signal level is estimated to be 3.5×105 cps.

  1. NOTE: Total body-calcium measurements: comparison of two delayed-gamma neutron activation facilities

    NASA Astrophysics Data System (ADS)

    Ma, R.; Ellis, K. J.; Yasumura, S.; Shypailo, R. J.; Pierson, R. N., Jr.

    1999-06-01

    This study compares two independently calibrated delayed-gamma neutron activation (DGNA) facilities, one at the Brookhaven National Laboratory (BNL), Upton, New York, and the other at the Children's Nutrition Research Center (CNRC), Houston, Texas that measure total body calcium (TBCa). A set of BNL phantoms was sent to CNRC for neutron activation analysis, and a set of CNRC phantoms was measured at BNL. Both facilities showed high precision (<2%), and the results were in good agreement, within 5%.

  2. Measuring and imaging diffusion with multiple scan speed image correlation spectroscopy.

    PubMed

    Gröner, Nadine; Capoulade, Jérémie; Cremer, Christoph; Wachsmuth, Malte

    2010-09-27

    The intracellular mobility of biomolecules is determined by transport and diffusion as well as molecular interactions and is crucial for many processes in living cells. Methods of fluorescence microscopy like confocal laser scanning microscopy (CLSM) can be used to characterize the intracellular distribution of fluorescently labeled biomolecules. Fluorescence correlation spectroscopy (FCS) is used to describe diffusion, transport and photo-physical processes quantitatively. As an alternative to FCS, spatially resolved measurements of mobilities can be implemented using a CLSM by utilizing the spatio-temporal information inscribed into the image by the scan process, referred to as raster image correlation spectroscopy (RICS). Here we present and discuss an extended approach, multiple scan speed image correlation spectroscopy (msICS), which benefits from the advantages of RICS, i.e. the use of widely available instrumentation and the extraction of spatially resolved mobility information, without the need of a priori knowledge of diffusion properties. In addition, msICS covers a broad dynamic range, generates correlation data comparable to FCS measurements, and allows to derive two-dimensional maps of diffusion coefficients. We show the applicability of msICS to fluorophores in solution and to free EGFP in living cells.

  3. Gamma-ray Output Spectra from 239 Pu Fission

    DOE PAGES

    Ullmann, John

    2015-05-25

    The gamma-ray multiplicities, individual gamma-ray energy spectra, and total gamma energy spectra following neutron-induced fission of 239Pu were measured using the DANCE detector at Los Alamos. Corrections for detector response were made using a forward-modeling technique based on propagating sets of gamma rays generated from a paramaterized model through a GEANT model of the DANCE array and adjusting the parameters for best fit to the measured spectra. The results for the gamma-ray spectrum and multiplicity are in general agreement with previous results, but the measured total gamma-ray energy is about 10% higher. We found that a dependence of the gamma-raymore » spectrum on the gamma-ray multplicity was also observed. Finally, global model calculations of the multiplicity and gamma energy distributions are in good agreement with the data, but predict a slightly softer total-energy distribution.« less

  4. Gamma-ray spectroscopy in the decay of (83)Se to levels of (83)Br.

    PubMed

    Krane, K S

    2015-03-01

    High-resolution γ ray spectroscopy experiments have been done to study the emissions from the radioactive decay of 22-min (83g)Se produced from neutron capture using samples of enriched (82)Se. Energy and intensity values have been obtained to roughly an order of magnitude greater precision than in previous studies. Based on energy sums, 2 new levels are proposed in the daughter (83)Br and one previously proposed level is shown to be doubtful. Some 25 new transitions appear to decay with the (83)Se halflife, about half of which can be accommodated among the previous or newly proposed levels. Several previous γ ray placements are shown to be inconsistent with the new determinations of the (83)Br energy levels, but cannot be accommodated anywhere else among the known levels. As a result of the missing γ ray placements, some of the β branchings in the decay to levels of (83)Br appear to be negative. Gamma rays from the 2.4-h decay of the daughter (83)Br to levels of (83)Kr have also been observed, along with decays of (81g)(,m)Se present as a small impurity in the enriched samples and also as a strong component in irradiated samples of natural Se. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Radionuclidic purity measurements for cyclotron-produced 99mTc via 100Mo(p,2n) at 18 MeV

    NASA Astrophysics Data System (ADS)

    Buckley, K.; Tanguay, J.; Hou, X.; Stothers, L.; Vuckovic, M.; Frantzen, K.; Cockburn, N.; Corsaut, J.; Dodd, M.; Goodbody, A.; Hanemaayer, V.; Hook, B.; Klug, J.; Kovacs, M.; Kumlin, J.; McDiarmid, S.; McEwan, J.; Prato, F.; Ruddock, P.; Valiant, J.; Zeisler, S.; Ruth, T.; Celler, A.; Benard, F.; Schaffer, P.

    2017-05-01

    The radionuclidic purity of cyclotron-produced 99mTc has been measured by gamma ray spectroscopy and compared to the results of a quick release test modeled after the molybdenum breakthrough test performed on generator-derived 99mTc. Excellent radionuclidic purity is reported for samples produced at BCCA during our clinical trial. The quick release test results agree well with the gamma ray analysis.

  6. Measurement of sigma chi c2 B(chi c2-->J/psi gamma)/sigma chi c1 B(chi c1 -->J/psi gamma) in pp collisions at square root s=1.96 TeV.

    PubMed

    Abulencia, A; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Ambrose, D; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arguin, J-F; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Bedeschi, F; Behari, S; Belforte, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Budroni, S; Burkett, K; Busetto, G; Bussey, P; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carillo, S; Carlsmith, D; Carosi, R; Carron, S; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciljak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; Cyr, D; DaRonco, S; Datta, M; D'Auria, S; Davies, T; D'Onofrio, M; Dagenhart, D; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; Dell'Orso, M; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; DiTuro, P; Dörr, C; Donati, S; Donega, M; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Foland, A; Forrester, S; Foster, G W; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, A; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Griffiths, M; Grinstein, S; Grosso-Pilcher, C; Group, R C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ishizawa, Y; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jensen, H; Jeon, E J; Jindariani, S; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kovalev, A; Kraan, A C; Kraus, J; Kravchenko, I; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Loverre, P; Lu, R-S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Manca, G; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Nachtman, J; Nagano, A; Naganoma, J; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nigmanov, T; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ranjan, N; Rappoccio, S; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Sabik, S; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Saltzberg, D; Sánchez, C; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Sjolin, J; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Takikawa, K; Tanaka, M; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuchiya, R; Tsuno, S; Turini, N; Ukegawa, F; Unverhau, T; Uozumi, S; Usynin, D; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Veramendi, G; Veszpremi, V; Vidal, R; Vila, I; Vilar, R; Vine, T; Vollrath, I; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, J; Wagner, W; Wallny, R; Wang, S M; Warburton, A; Waschke, S; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zhou, J; Zucchelli, S

    2007-06-08

    We measure the ratio of cross section times branching fraction, Rp=sigma chi c2 B(chi c2-->J/psi gamma)/sigma chi c1 B(chi c1-->J/psi gamma), in 1.1 fb(-1) of pp collisions at square root s=1.96 TeV. This measurement covers the kinematic range pT(J/psi)>4.0 GeV/c, |eta(J/psi)<1.0, and pT(gamma)>1.0 GeV/c. For events due to prompt processes, we find Rp=0.395+/-0.016(stat)+/-0.015(syst). This result represents a significant improvement in precision over previous measurements of prompt chi c1,2 hadro production.

  7. Correlation between near infrared spectroscopy and electrical techniques in measuring skin moisture content

    NASA Astrophysics Data System (ADS)

    Mohamad, M.; Sabbri, A. R. M.; Mat Jafri, M. Z.; Omar, A. F.

    2014-11-01

    Near infrared (NIR) spectroscopy technique serves as an important tool for the measurement of moisture content of skin owing to the advantages it has over the other techniques. The purpose of the study is to develop a correlation between NIR spectrometer with electrical conventional techniques for skin moisture measurement. A non-invasive measurement of moisture content of skin was performed on different part of human face and hand under control environment (temperature 21 ± 1 °C, relative humidity 45 ± 5 %). Ten healthy volunteers age between 21-25 (male and female) participated in this study. The moisture content of skin was measured using DermaLab® USB Moisture Module, Scalar Moisture Checker and NIR spectroscopy (NIRQuest). Higher correlation was observed between NIRQuest and Dermalab moisture probe with a coefficient of determination (R2) above 70 % for all the subjects. However, the value of R2 between NIRQuest and Moisture Checker was observed to be lower with the R2 values ranges from 51.6 to 94.4 %. The correlation of NIR spectroscopy technique successfully developed for measuring moisture content of the skin. The analysis of this correlation can help to establish novel instruments based on an optical system in clinical used especially in the dermatology field.

  8. Measurement of Fission Neutron Spectrum and Multiplicity using a Gamma Tag Double Time-of-flight Setup

    NASA Astrophysics Data System (ADS)

    Blain, E.; Daskalakis, A.; Danon, Y.

    2014-05-01

    Recent efforts have been made to improve the prompt fission neutron spectrum and nu-bar measurements for Uranium and Plutonium isotopes particularly in the keV region. A system has been designed at Rensselaer Polytechnic Institute (RPI) utilizing an array of EJ-301 liquid scintillators as well as lithium glass and plastic scintillators to experimentally determine these values. An array of BaF2 detectors was recently obtained from Oak Ridge National Laboratory to be used in conjunction with the neutron detectors. The system uses a novel gamma tagging method for fission which can offer an improvement over conventional fission chambers due to increased sample mass. A coincidence requirement on the gamma detectors from prompt fission gammas is used as the fission tag for the system as opposed to fission fragments in a conventional fission chamber. The system utilizes pulse digitization using Acqiris 8 bit digitizer boards which allow for gamma/neutron pulse height discrimination on the liquid scintillators during post processing. Additionally, a 252Cf fission chamber was designed and constructed at RPI which allowed for optimization and testing of the system without the need for an external neutron source. The characteristics of the gamma tagging method such as false detection rate and detection efficiency were determined using this fission chamber and verified using MCNP Polimi modeling. Prompt fission neutron spectrum data has been taken using the fission chamber focusing on the minimum detectable neutron energy for each of the various detectors. Plastic scintillators were found to offer a significant improvement over traditional liquid scintillators allowing energy measurements down to 50 keV. Background was also characterized for all detectors and will be discussed.

  9. Formation of gamma'-Ni3Al via the Peritectoid Reaction: gamma plus beta (+Al2O3) equals gamma'(+Al2O3)

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2008-01-01

    The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8 - 32 at.%Al and temperature range T = 1400 - 1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma'-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3) = gamma + beta (+ Al2O3), at 1640 plus or minus 1 K and a liquid composition of 24.8 plus or minus 0.2 at.%Al (at an unknown oxygen content). The {gamma + beta + Al2O3} phase field is stable over the temperature range 1633 - 1640 K, and gamma'-Ni3Al forms via the peritectiod, gamma + beta (+ Al2O3) = gamma'(+ Al2O3), at 1633 plus or minus 1 K. This behavior is inconsistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma'-Ni3Al phase field.

  10. Hard gamma radiation background from coding collimator of gamma telescope under space experiment conditions

    NASA Astrophysics Data System (ADS)

    Aleksandrov, A. P.; Berezovoy, A. N.; Galper, A. M.; Grachev, V. M.; Dmitrenko, V. V.; Kirillov-Ugryumov, V. G.; Lebedev, V. V.; Lyakhov, V. A.; Moiseyev, A. A.; Ulin, S. Y.

    1985-09-01

    Coding collimators are used to improve the angular resolution of gamma-ray telescopes at energies above 50 MeV. However, the interaction of cosmic rays with the collimation material can lead to the appearance of a gamma-ray background flux which can have a deleterious effect on measurement efficiency. An experiment was performed on the Salyut-6-Soyuz spacecraft system with the Elena-F small-scale gamma-ray telescope in order to measure the magnitude of this background. It is shown that, even at a zenith angle of approximately zero degrees (the angle at which the gamma-ray observations are made), the coding collimator has only an insignificant effect on the background conditions.

  11. Hard X-ray and low-energy gamma-ray spectrometers

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Crannell, C. J.; Orwig, L. E.; Forrest, D. J.; Lin, R. P.; Starr, R.

    1988-01-01

    Basic principles of operation and characteristics of scintillation and semi-conductor detectors used for solar hard X-ray and gamma-ray spectrometers are presented. Scintillation materials such as NaI offer high stopping power for incident gamma rays, modest energy resolution, and relatively simple operation. They are, to date, the most often used detector in solar gamma-ray spectroscopy. The scintillator BGO has higher stopping power than NaI, but poorer energy resolution. The primary advantage of semi-conductor materials such as Ge is their high-energy resolution. Monte-Carlo simulations of the response of NaI and Ge detectors to model solar flare inputs show the benefit of high resoluton for studying spectral lines. No semi-conductor material besides Ge is currently available with adequate combined size and purity to make general-use hard X-ray and gamma-ray detectors for solar studies.

  12. GRB 080517: a local, low-luminosity gamma-ray burst in a dusty galaxy at z = 0.09

    NASA Astrophysics Data System (ADS)

    Stanway, Elizabeth R.; Levan, Andrew J.; Tanvir, Nial; Wiersema, Klaas; van der Horst, Alexander; Mundell, Carole G.; Guidorzi, Cristiano

    2015-02-01

    We present an analysis of the photometry and spectroscopy of the host galaxy of Swift-detected GRB 080517. From our optical spectroscopy, we identify a redshift of z = 0.089 ± 0.003, based on strong emission lines, making this a rare example of a very local, low-luminosity, long gamma-ray burst. The galaxy is detected in the radio with a flux density of S4.5 GHz = 0.22 ± 0.04 mJy - one of relatively few known gamma-ray bursts hosts with a securely measured radio flux. Both optical emission lines and a strong detection at 22 μm suggest that the host galaxy is forming stars rapidly, with an inferred star formation rate ˜16 M⊙ yr-1 and a high dust obscuration (E(B - V) > 1, based on sightlines to the nebular emission regions). The presence of a companion galaxy within a projected distance of 25 kpc, and almost identical in redshift, suggests that star formation may have been triggered by galaxy-galaxy interaction. However, fitting of the remarkably flat spectral energy distribution from the ultraviolet through to the infrared suggests that an older, 500 Myr post-starburst stellar population is present along with the ongoing star formation. We conclude that the host galaxy of GRB 080517 is a valuable addition to the still very small sample of well-studied local gamma-ray burst hosts.

  13. Multi-fiber strains measured by micro-Raman spectroscopy: Principles and experiments

    NASA Astrophysics Data System (ADS)

    Lei, Zhenkun; Wang, Yunfeng; Qin, Fuyong; Qiu, Wei; Bai, Ruixiang; Chen, Xiaogang

    2016-02-01

    Based on widely used axial strain measurement method of Kevlar single fiber, an original theoretical model and measurement principle of application of micro-Raman spectroscopy to multi-fiber strains in a fiber bundle were established. The relationship between the nominal Raman shift of fiber bundle and the multi-fiber strains was deduced. The proposed principle for multi-fiber strains measurement is consistent with two special cases: single fiber deformation and multi-fiber deformation under equal strain. It is found experimentally that the distribution of Raman scattering intensity of a Kevlar 49 fiber as a function of distance between a fiber and the laser spot center follows a Gaussian function. Combining the Raman-shift/strain relationship of the Kevlar 49 single fiber and the uniaxial tension measured by micro-Raman spectroscopy, the Raman shift as a function of strain was obtained. Then the Raman peak at 1610 cm-1 for the Kevlar 49 fiber was fitted to a Lorentzian function and the FWHM showed a quadratic increase with the fiber strain. Finally, a dual-fiber tensile experiment was performed to verify the adequacy of the Raman technique for the measurement of multi-fiber strains.

  14. Continuous Wave Ring-Down Spectroscopy for Velocity Distribution Measurements in Plasma

    NASA Astrophysics Data System (ADS)

    McCarren, Dustin W.

    Cavity Ring-Down Spectroscopy CRDS is a proven, ultra-sensitive, cavity enhanced absorption spectroscopy technique. When combined with a continuous wavelength (CW) diode laser that has a sufficiently narrow line width, the Doppler broadened absorption line, i.e., the velocity distribution functions (VDFs) of the absorbing species, can be measured. Measurements of VDFs can be made using established techniques such as laser induced fluorescence (LIF). However, LIF suffers from the requirement that the initial state of the LIF sequence have a substantial density and that the excitation scheme fluoresces at an easily detectable wavelength. This usually limits LIF to ions and atoms with large metastable state densities for the given plasma conditions. CW-CRDS is considerably more sensitive than LIF and can potentially be applied to much lower density populations of ion and atom states. Also, as a direct absorption technique, CW-CRDS measurements only need to be concerned with the species' absorption wavelength and provide an absolute measure of the line integrated initial state density. Presented in this work are measurements of argon ion and neutral VDFs in a helicon plasma using CW-CRDS and LIF.

  15. A Team Approach to the Development of Gamma Ray and x Ray Remote Sensing and in Situ Spectroscopy for Planetary Exploration Missions

    NASA Technical Reports Server (NTRS)

    Trombka, J. I.; Floyd, S.; Ruitberg, A.; Evans, L.; Starr, R.; Metzger, A.; Reedy, R.; Drake, D.; Moss, C.; Edwards, B.

    1993-01-01

    An important part of the investigation of planetary origin and evolution is the determination of the surface composition of planets, comets, and asteroids. Measurements of discrete line X-ray and gamma ray emissions from condensed bodies in space can be used to obtain both qualitative and quantitative elemental composition information. The Planetary Instrumentation Definition and Development Program (PIDDP) X-Ray/Gamma Ray Team has been established to develop remote sensing and in situ technologies for future planetary exploration missions.

  16. Arcsec source location measurements in gamma-ray astronomy from a lunar observatory

    NASA Astrophysics Data System (ADS)

    Koch, D. G.; Hughes, B. E.

    1990-03-01

    The physical processes typically used in the detection of high energy gamma-rays do not permit good angular resolution, which makes difficult the unambiguous association of discrete gamma-ray sources with objects emitting at other wavelengths. This problem can be overcome by placing gamma-ray detectors on the moon and using the horizon as an occulting edge to achieve arcsec resolution. For the purpose of discussion, this concept is examined for gamma rays above about 20 MeV for which pair production dominates the detection process and locally-generated nuclear gamma rays do not contribute to the background.

  17. Uranium, radium and thorium in soils with high-resolution gamma spectroscopy, MCNP-generated efficiencies, and VRF non-linear full-spectrum nuclide shape fitting

    NASA Astrophysics Data System (ADS)

    Metzger, Robert; Riper, Kenneth Van; Lasche, George

    2017-09-01

    A new method for analysis of uranium and radium in soils by gamma spectroscopy has been developed using VRF ("Visual RobFit") which, unlike traditional peak-search techniques, fits full-spectrum nuclide shapes with non-linear least-squares minimization of the chi-squared statistic. Gamma efficiency curves were developed for a 500 mL Marinelli beaker geometry as a function of soil density using MCNP. Collected spectra were then analyzed using the MCNP-generated efficiency curves and VRF to deconvolute the 90 keV peak complex of uranium and obtain 238U and 235U activities. 226Ra activity was determined either from the radon daughters if the equilibrium status is known, or directly from the deconvoluted 186 keV line. 228Ra values were determined from the 228Ac daughter activity. The method was validated by analysis of radium, thorium and uranium soil standards and by inter-comparison with other methods for radium in soils. The method allows for a rapid determination of whether a sample has been impacted by a man-made activity by comparison of the uranium and radium concentrations to those that would be expected from a natural equilibrium state.

  18. Strontium iodide scintillators for high energy resolution gamma ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Wilson, Cody M.; van Loef, Edgar V.; Glodo, Jarek; Cherepy, Nerine; Hull, Giulia; Payne, Stephen; Choong, Woon-Seng; Moses, William; Shah, Kanai S.

    2008-08-01

    Recently SrI2, a scintillator patented by Hofstadter in 1968, has been rediscovered and shown to possess remarkable scintillation properties. The light output of SrI2:Eu2+ has been measured to be even higher than previously observed and exceeds 120,000 photons/MeV, making it one of the brightest scintillators in existence. The crystal also has excellent energy resolution of less than 3% at 662 keV. The response is highly linear over a wide range of gamma ray energies. The emission of SrI2:Eu2+ and SrI2:Ce3+/Na+ is well-matched to both photomultiplier tubes and blue-enhanced silicon photodiodes. While SrI2:Eu2+ is relatively slow, SrI2:Ce3+/Na+ has a fast response. SrI2 crystals with many different dopant concentrations have been grown and characterized. In this presentation, crystal growth techniques as well as the effects of dopant concentration on the scintillation properties of SrI2, over the range 0.5% to 8% Eu2+ and 0.5% to 2% Ce3+/Na+, will be discussed in detail.

  19. Accuracy and stability of measuring GABA, glutamate, and glutamine by proton magnetic resonance spectroscopy: A phantom study at 4 Tesla

    PubMed Central

    Henry, Michael E.; Lauriat, Tara L.; Shanahan, Meghan; Renshaw, Perry F.; Jensen, J. Eric

    2015-01-01

    Proton magnetic resonance spectroscopy has the potential to provide valuable information about alterations in gamma-aminobutyric acid (GABA), glutamate (Glu), and glutamine (Gln) in psychiatric and neurological disorders. In order to use this technique effectively, it is important to establish the accuracy and reproducibility of the methodology. In this study, phantoms with known metabolite concentrations were used to compare the accuracy of 2D J-resolved MRS, single-echo 30 ms PRESS, and GABA-edited MEGA-PRESS for measuring all three aforementioned neurochemicals simultaneously. The phantoms included metabolite concentrations above and below the physiological range and scans were performed at baseline, 1 week, and 1 month time-points. For GABA measurement, MEGA-PRESS proved optimal with a measured-to-target correlation of R2 = 0.999, with J-resolved providing R2 = 0.973 for GABA. All three methods proved effective in measuring Glu with R2 = 0.987 (30 ms PRESS), R2 = 0.996 (J-resolved) and R2 = 0.910 (MEGA-PRESS). J-resolved and MEGA-PRESS yielded good results for Gln measures with respective R2 = 0.855 (J-resolved) and R2 = 0.815 (MEGA-PRESS). The 30 ms PRESS method proved ineffective in measuring GABA and Gln. When measurement stability at in vivo concentration was assessed as a function of varying spectral quality, J-resolved proved the most stable and immune to signal-to-noise and linewidth fluctuation compared to MEGA-PRESS and 30 ms PRESS. PMID:21130670

  20. Accuracy and stability of measuring GABA, glutamate, and glutamine by proton magnetic resonance spectroscopy: A phantom study at 4 Tesla

    NASA Astrophysics Data System (ADS)

    Henry, Michael E.; Lauriat, Tara L.; Shanahan, Meghan; Renshaw, Perry F.; Jensen, J. Eric

    2011-02-01

    Proton magnetic resonance spectroscopy has the potential to provide valuable information about alterations in gamma-aminobutyric acid (GABA), glutamate (Glu), and glutamine (Gln) in psychiatric and neurological disorders. In order to use this technique effectively, it is important to establish the accuracy and reproducibility of the methodology. In this study, phantoms with known metabolite concentrations were used to compare the accuracy of 2D J-resolved MRS, single-echo 30 ms PRESS, and GABA-edited MEGA-PRESS for measuring all three aforementioned neurochemicals simultaneously. The phantoms included metabolite concentrations above and below the physiological range and scans were performed at baseline, 1 week, and 1 month time-points. For GABA measurement, MEGA-PRESS proved optimal with a measured-to-target correlation of R2 = 0.999, with J-resolved providing R2 = 0.973 for GABA. All three methods proved effective in measuring Glu with R2 = 0.987 (30 ms PRESS), R2 = 0.996 (J-resolved) and R2 = 0.910 (MEGA-PRESS). J-resolved and MEGA-PRESS yielded good results for Gln measures with respective R2 = 0.855 (J-resolved) and R2 = 0.815 (MEGA-PRESS). The 30 ms PRESS method proved ineffective in measuring GABA and Gln. When measurement stability at in vivo concentration was assessed as a function of varying spectral quality, J-resolved proved the most stable and immune to signal-to-noise and linewidth fluctuation compared to MEGA-PRESS and 30 ms PRESS.

  1. Natural radioactivity investigation in Dam sediments of northeast Algeria using gamma spectroscopy

    NASA Astrophysics Data System (ADS)

    Benrachi, Fatima; Bouhila, Ghania; Saadi, Asma; Ramdhane, Mourad

    2017-09-01

    Current research paper intends to estimate the natural radioactivity levels in sediments samples collected from Beni Haroun Dam in the northeast Algeria, using high resolution HPGe detector. The mean activity concentrations values measured for the radionuclides 232Th, 226Ra and 40K are 18.9 ± 1.9, 37.3 ± 2.7 and 149.9 ± 5.5 Bq/kg, respectively. The 137Cs anthropogenic radionuclide has been observed with maximum activity concentration value of 0.8 ± 0.4 Bq/kg, which is considered an insignificant amount. In order to assess the radiological threat of gamma radiations emitted by these radionuclides on the health of the population, absorbed dose rate, annual effective dose equivalent and radiation hazard indices were had been calculated. The obtained values are compared with the world wide average ones.

  2. Performance of the prototype LaBr3 spectrometer developed for the JET gamma-ray camera upgrade.

    PubMed

    Rigamonti, D; Muraro, A; Nocente, M; Perseo, V; Boltruczyk, G; Fernandes, A; Figueiredo, J; Giacomelli, L; Gorini, G; Gosk, M; Kiptily, V; Korolczuk, S; Mianowski, S; Murari, A; Pereira, R C; Cippo, E P; Zychor, I; Tardocchi, M

    2016-11-01

    In this work, we describe the solution developed by the gamma ray camera upgrade enhancement project to improve the spectroscopic properties of the existing JET γ-ray camera. Aim of the project is to enable gamma-ray spectroscopy in JET deuterium-tritium plasmas. A dedicated pilot spectrometer based on a LaBr 3 crystal coupled to a silicon photo-multiplier has been developed. A proper pole zero cancellation network able to shorten the output signal to a length of 120 ns has been implemented allowing for spectroscopy at MHz count rates. The system has been characterized in the laboratory and shows an energy resolution of 5.5% at E γ = 0.662 MeV, which extrapolates favorably in the energy range of interest for gamma-ray emission from fast ions in fusion plasmas.

  3. Coupling between gamma-band power and cerebral blood volume during recurrent acute neocortical seizures.

    PubMed

    Harris, Sam; Ma, Hongtao; Zhao, Mingrui; Boorman, Luke; Zheng, Ying; Kennerley, Aneurin; Bruyns-Haylett, Michael; Overton, Paul G; Berwick, Jason; Schwartz, Theodore H

    2014-08-15

    Characterization of neural and hemodynamic biomarkers of epileptic activity that can be measured using non-invasive techniques is fundamental to the accurate identification of the epileptogenic zone (EZ) in the clinical setting. Recently, oscillations at gamma-band frequencies and above (>30 Hz) have been suggested to provide valuable localizing information of the EZ and track cortical activation associated with epileptogenic processes. Although a tight coupling between gamma-band activity and hemodynamic-based signals has been consistently demonstrated in non-pathological conditions, very little is known about whether such a relationship is maintained in epilepsy and the laminar etiology of these signals. Confirmation of this relationship may elucidate the underpinnings of perfusion-based signals in epilepsy and the potential value of localizing the EZ using hemodynamic correlates of pathological rhythms. Here, we use concurrent multi-depth electrophysiology and 2-dimensional optical imaging spectroscopy to examine the coupling between multi-band neural activity and cerebral blood volume (CBV) during recurrent acute focal neocortical seizures in the urethane-anesthetized rat. We show a powerful correlation between gamma-band power (25-90 Hz) and CBV across cortical laminae, in particular layer 5, and a close association between gamma measures and multi-unit activity (MUA). Our findings provide insights into the laminar electrophysiological basis of perfusion-based imaging signals in the epileptic state and may have implications for further research using non-invasive multi-modal techniques to localize epileptogenic tissue. Copyright © 2014. Published by Elsevier Inc.

  4. Measurement of the branching fraction of Gamma(4S) --> B0B0.

    PubMed

    Aubert, B; Barate, R; Boutigny, D; Couderc, F; Karyotakis, Y; Lees, J P; Poireau, V; Tisserand, V; Zghiche, A; Grauges-Pous, E; Palano, A; Pappagallo, M; Pompili, A; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Ofte, I; Stugu, B; Abrams, G S; Borgland, A W; Breon, A B; Brown, D N; Button-Shafer, J; Cahn, R N; Charles, E; Day, C T; Gill, M S; Gritsan, A V; Groysman, Y; Jacobsen, R G; Kadel, R W; Kadyk, J; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Lynch, G; Mir, L M; Oddone, P J; Orimoto, T J; Pripstein, M; Roe, N A; Ronan, M T; Wenzel, W A; Barrett, M; Ford, K E; Harrison, T J; Hart, A J; Hawkes, C M; Morgan, S E; Watson, A T; Fritsch, M; Goetzen, K; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Peters, K; Schroeder, T; Steinke, M; Boyd, J T; Burke, J P; Chevalier, N; Cottingham, W N; Kelly, M P; Cuhadar-Donszelmann, T; Hearty, C; Knecht, N S; Mattison, T S; McKenna, J A; Thiessen, D; Khan, A; Kyberd, P; Teodorescu, L; Blinov, A E; Blinov, V E; Bukin, A D; Druzhinin, V P; Golubev, V B; Ivanchenko, V N; Kravchenko, E A; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Yushkov, A N; Best, D; Bondioli, M; Bruinsma, M; Chao, M; Eschrich, I; Kirkby, D; Lankford, A J; Mandelkern, M; Mommsen, R K; Roethel, W; Stoker, D P; Buchanan, C; Hartfiel, B L; Weinstein, A J R; Foulkes, S D; Gary, J W; Long, O; Shen, B C; Wang, K; Zhang, L; Del Re, D; Hadavand, H K; Hill, E J; MacFarlane, D B; Paar, H P; Rahatlou, Sh; Sharma, V; Berryhill, J W; Campagnari, C; Cunha, A; Dahmes, B; Hong, T M; Lu, A; Mazur, M A; Richman, J D; Verkerke, W; Beck, T W; Eisner, A M; Flacco, C J; Heusch, C A; Kroseberg, J; Lockman, W S; Nesom, G; Schalk, T; Schumm, B A; Seiden, A; Spradlin, P; Williams, D C; Wilson, M G; Albert, J; Chen, E; Dubois-Felsmann, G P; Dvoretskii, A; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Ryd, A; Samuel, A; Yang, S; Jayatilleke, S; Mancinelli, G; Meadows, B T; Sokoloff, M D; Blanc, F; Bloom, P; Chen, S; Ford, W T; Nauenberg, U; Olivas, A; Rankin, P; Ruddick, W O; Smith, J G; Ulmer, K A; Zhang, J; Chen, A; Eckhart, E A; Harton, J L; Soffer, A; Toki, W H; Wilson, R J; Zeng, Q; Spaan, B; Altenburg, D; Brandt, T; Brose, J; Dickopp, M; Feltresi, E; Hauke, A; Lacker, H M; Maly, E; Nogowski, R; Otto, S; Petzold, A; Schott, G; Schubert, J; Schubert, K R; Schwierz, R; Sundermann, J E; Bernard, D; Bonneaud, G R; Grenier, P; Schrenk, S; Thiebaux, Ch; Vasileiadis, G; Verderi, M; Bard, D J; Clark, P J; Gradl, W; Muheim, F; Playfer, S; Xie, Y; Andreotti, M; Azzolini, V; Bettoni, D; Bozzi, C; Calabrese, R; Cibinetto, G; Luppi, E; Negrini, M; Piemontese, L; Sarti, A; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Finocchiaro, G; Patteri, P; Peruzzi, I M; Piccolo, M; Zallo, A; Buzzo, A; Capra, R; Contri, R; Lo Vetere, M; Macri, M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Bailey, S; Brandenburg, G; Chaisanguanthum, K S; Morii, M; Won, E; Dubitzky, R S; Langenegger, U; Marks, J; Uwer, U; Bhimji, W; Bowerman, D A; Dauncey, P D; Egede, U; Gaillard, J R; Morton, G W; Nash, J A; Nikolich, M B; Taylor, G P; Charles, M J; Grenier, G J; Mallik, U; Cochran, J; Crawley, H B; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Yi, J; Arnaud, N; Davier, M; Giroux, X; Grosdidier, G; Höcker, A; Le Diberder, F; Lepeltier, V; Lutz, A M; Petersen, T C; Pierini, M; Plaszczynski, S; Rodier, S; Roudeau, P; Schune, M H; Stocchi, A; Wormser, G; Cheng, C H; Lange, D J; Simani, M C; Wright, D M; Bevan, A J; Chavez, C A; Coleman, J P; Forster, I J; Fry, J R; Gabathuler, E; Gamet, R; George, K A; Hutchcroft, D E; Parry, R J; Payne, D J; Touramanis, C; Cormack, C M; Di Lodovico, F; Brown, C L; Cowan, G; Flack, R L; Flaecher, H U; Green, M G; Jackson, P S; McMahon, T R; Ricciardi, S; Salvatore, F; Winter, M A; Brown, D; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Hodgkinson, M C; Lafferty, G D; Naisbit, M T; Williams, J C; Chen, C; Farbin, A; Hulsbergen, W D; Jawahery, A; Kovalskyi, D; Lae, C K; Lillard, V; Roberts, D A; Blaylock, G; Dallapiccola, C; Hertzbach, S S; Kofler, R; Koptchev, V B; Moore, T B; Saremi, S; Staengle, H; Willocq, S; Cowan, R; Koeneke, K; Sciolla, G; Sekula, S J; Taylor, F; Yamamoto, R K; Patel, P M; Robertson, S H; Lazzaro, A; Lombardo, V; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Reidy, J; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Taras, P; Nicholson, H; Cavallo, N; De Nardo, G; Fabozzi, F; Gatto, C; Lista, L; Monorchio, D; Paolucci, P; Piccolo, D; Sciacca, C; Baak, M; Bulten, H; Raven, G; Snoek, H L; Wilden, L; Jessop, C P; Losecco, J M; Allmendinger, T; Benelli, G; Gan, K K; Honscheid, K; Hufnagel, D; Kagan, H; Kass, R; Pulliam, T; Rahimi, A M; Ter-Antonyan, R; Wong, Q K; Brau, J; Frey, R; Igonkina, O; Lu, M; Potter, C T; Sinev, N B; Strom, D; Torrence, E; Colecchia, F; Dorigo, A; Galeazzi, F; Margoni, M; Morandin, M; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; Benayoun, M; Briand, H; Chauveau, J; David, P; Del Buono, L; de la Vaissière, Ch; Hamon, O; John, M J J; Leruste, Ph; Malclès, J; Ocariz, J; Roos, L; Therin, G; Behera, P K; Gladney, L; Guo, Q H; Panetta, J; Biasini, M; Covarelli, R; Pioppi, M; Angelini, C; Batignani, G; Bettarini, S; Bucci, F; Calderini, G; Carpinelli, M; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Morganti, M; Neri, N; Paoloni, E; Rama, M; Rizzo, G; Simi, G; Walsh, J; Haire, M; Judd, D; Paick, K; Wagoner, D E; Danielson, N; Elmer, P; Lau, Y P; Lu, C; Olsen, J; Smith, A J S; Telnov, A V; Bellini, F; Cavoto, G; D'Orazio, A; Di Marco, E; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Li Gioi, L; Mazzoni, M A; Morganti, S; Piredda, G; Polci, F; Tehrani, F Safai; Voena, C; Christ, S; Schröder, H; Wagner, G; Waldi, R; Adye, T; De Groot, N; Franek, B; Gopal, G P; Olaiya, E O; Wilson, F F; Aleksan, R; Emery, S; Gaidot, A; Ganzhur, S F; Giraud, P-F; Graziani, G; de Monchenault, G Hamel; Kozanecki, W; Legendre, M; London, G W; Mayer, B; Vasseur, G; Yèche, Ch; Zito, M; Purohit, M V; Weidemann, A W; Wilson, J R; Yumiceva, F X; Abe, T; Allen, M; Aston, D; Bartoldus, R; Berger, N; Boyarski, A M; Buchmueller, O L; Claus, R; Convery, M R; Cristinziani, M; Dingfelder, J C; Dong, D; Dorfan, J; Dujmic, D; Dunwoodie, W; Fan, S; Field, R C; Glanzman, T; Gowdy, S J; Hadig, T; Halyo, V; Hast, C; Hryn'ova, T; Innes, W R; Kelsey, M H; Kim, P; Kocian, M L; Leith, D W G S; Libby, J; Luitz, S; Luth, V; Lynch, H L; Marsiske, H; Messner, R; Mohapatra, A K; Muller, D R; O'Grady, C P; Ozcan, V E; Perazzo, A; Perl, M; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Snyder, A; Soha, A; Stelzer, J; Strube, J; Su, D; Sullivan, M K; Thompson, J; Va'vra, J; Wagner, S R; Weaver, M; Wisniewski, W J; Wittgen, M; Wright, D H; Yarritu, A K; Young, C C; Burchat, P R; Edwards, A J; Majewski, S A; Petersen, B A; Roat, C; Ahmed, M; Ahmed, S; Alam, M S; Ernst, J A; Saeed, M A; Saleem, M; Wappler, F R; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Kim, H; Ritchie, J L; Satpathy, A; Schwitters, R F; Izen, J M; Kitayama, I; Lou, X C; Ye, S; Bianchi, F; Bona, M; Gallo, F; Gamba, D; Bomben, M; Bosisio, L; Cartaro, C; Cossutti, F; Ricca, G Della; Dittongo, S; Grancagnolo, S; Lanceri, L; Poropat, P; Vitale, L; Vuagnin, G; Martinez-Vidal, F; Panvini, R S; Banerjee, Sw; Bhuyan, B; Brown, C M; Fortin, D; Hamano, K; Jackson, P D; Kowalewski, R; Roney, J M; Sobie, R J; Back, J J; Harrison, P F; Latham, T E; Mohanty, G B; Band, H R; Chen, X; Cheng, B; Dasu, S; Datta, M; Eichenbaum, A M; Flood, K T; Graham, M; Hollar, J J; Johnson, J R; Kutter, P E; Li, H; Liu, R; Mellado, B; Mihalyi, A; Pan, Y; Prepost, R; Tan, P; von Wimmersperg-Toeller, J H; Wu, J; Wu, S L; Yu, Z; Greene, M G; Neal, H

    2005-07-22

    We report the first measurement of the branching fraction f(00) for Gamma(4S) --> B(0)B(0). The data sample consists of 81.7 fb(-1) collected at the Gamma(4S) resonance with the BABAR detector at the SLAC PEP-II asymmetric-energy e(+)e(-) storage ring. Using partial reconstruction of the decay B(0) --> D(*+) l(-)nu(l) in which only the charged lepton and the soft pion from the decay D(*+) --> D(0)pi(+) are reconstructed, we obtain f(00) = 0.487 +/- 0.010(stat) +/- 0.008(syst). Our result does not depend on the branching fractions of B(0) --> D(*+)l(-)nu(l) and D(*+) --> D(0)pi(+) decays, on the ratio of the charged and neutral B meson lifetimes, nor on the assumption of isospin symmetry.

  5. Status of the nuclear measurement stations for the process control of spent fuel reprocessing at AREVA NC/La Hague

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Eleon, Cyrille; Passard, Christian; Hupont, Nicolas

    2015-07-01

    Nuclear measurements are used at AREVA NC/La Hague for the monitoring of spent fuel reprocessing. The process control is based on gamma-ray spectroscopy, passive neutron counting and active neutron interrogation, and gamma transmission measurements. The main objectives are criticality and safety, online process monitoring, and the determination of the residual fissile mass and activities in the metallic waste remained after fuel shearing and dissolution (empty hulls, grids, end pieces), which are put in radioactive waste drums before compaction. The whole monitoring system is composed of eight measurement stations which will be described in this paper. The main measurement stations no.more » 1, 3 and 7 are needed for criticality control. Before fuel element shearing for dissolution, station no. 1 allows determining the burn-up of the irradiated fuel by gamma-ray spectroscopy with HP Ge (high purity germanium) detectors. The burn-up is correlated to the {sup 137}Cs and {sup 134}Cs gamma emission rates. The fuel maximal mass which can be loaded in one bucket of the dissolver is estimated from the lowest burn-up fraction of the fuel element. Station no. 3 is dedicated to the control of the correct fuel dissolution, which is performed with a {sup 137}Cs gamma ray measurement with a HP Ge detector. Station no. 7 allows estimating the residual fissile mass in the drums filled with the metallic residues, especially in the hulls, from passive neutron counting (spontaneous fission and alpha-n reactions) and active interrogation (fission prompt neutrons induced by a pulsed neutron generator) with proportional {sup 3}He detectors. The measurement stations have been validated for the reprocessing of Uranium Oxide (UOX) fuels with a burn-up rate up to 60 GWd/t. This paper presents a brief overview of the current status of the nuclear measurement stations. (authors)« less

  6. Gamma-400 Science Objectives Built on the Current HE Gamma-Ray and CR Results

    NASA Technical Reports Server (NTRS)

    Moiseev, Alexander; Mitchell, John; Thompson, David

    2012-01-01

    The main scientific interest of the Russian Gamma-400 team: Observe gamma-rays above approximately 50 GeV with excellent energy and angular resolution with the goals of: (1) Studying the fine spectral structure of the isotropic high-energy gamma-radiation, (2) Attempting to identify the many still-unidentified Fermi-LAT gamma-ray sources. Gamma-400 will likely be the only space-based gamma-ray observatory operating at the end of the decade. In our proposed Gamma-400-LE version, it will substantially improve upon the capabilities of Fermi LAT and AGILE in both LE and HE energy range. Measuring gamma-rays from approx 20 MeV to approx 1 TeV for at least 7 years, Gamma-400-LE will address the topics of dark matter, cosmic ray origin and propagation, neutron stars, flaring pulsars, black holes, AGNs, GRBs, and actively participate in multiwavelength campaigns.

  7. Simultaneous measurement of unfrozen water content and ice content in frozen soil using gamma ray attenuation and TDR

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaohai; Zhou, Jian; Kinzelbach, Wolfgang; Stauffer, Fritz

    2014-12-01

    The freezing temperature of water in soil is not constant but varies over a range determined by soil texture. Consequently, the amounts of unfrozen water and ice change with temperature in frozen soil, which in turn affects hydraulic, thermal, and mechanical properties of frozen soil. In this paper, an Am-241 gamma ray source and time-domain reflectometry (TDR) were combined to measure unfrozen water content and ice content in frozen soil simultaneously. The gamma ray attenuation was used to determine total water content. The TDR was used to determine the dielectric constant of the frozen soil. Based on a four-phase mixing model, the amount of unfrozen water content in the frozen soil could be determined. The ice content was inferred by the difference between total water content and unfrozen water content. The gamma ray attenuation and the TDR were both calibrated by a gravimetric method. Water contents measured by gamma ray attenuation and TDR in an unfrozen silt column under infiltration were compared and showed that the two methods have the same accuracy and response to changes of water content. Unidirectional column freezing experiments were performed to apply the combined method of gamma ray attenuation and TDR for measuring unfrozen water content and ice content. The measurement error of the gamma ray attenuation and TDR was around 0.02 and 0.01 m3/m3, respectively. The overestimation of unfrozen water in frozen soil by TDR alone was quantified and found to depend on the amount of ice content. The higher the ice content, the larger the overestimation. The study confirmed that the combined method could accurately determine unfrozen water content and ice content in frozen soil. The results of soil column freezing experiments indicate that total water content distribution is affected by available pore space and the freezing front advance rate. It was found that there is similarity between the soil water characteristic and the soil freezing characteristic of

  8. Observation of psi(3770) --> pi pi J/psi and measurement of Gamma ee[psi(2S)].

    PubMed

    Adam, N E; Alexander, J P; Berkelman, K; Cassel, D G; Crede, V; Duboscq, J E; Ecklund, K M; Ehrlich, R; Fields, L; Galik, R S; Gibbons, L; Gittelman, B; Gray, R; Gray, S W; Hartill, D L; Heltsley, B K; Hertz, D; Jones, C D; Kandaswamy, J; Kreinick, D L; Kuznetsov, V E; Mahlke-Krüger, H; Meyer, T O; Onyisi, P U E; Patterson, J R; Peterson, D; Phillips, E A; Pivarski, J; Riley, D; Ryd, A; Sadoff, A J; Schwarthoff, H; Shi, X; Shepherd, M R; Stroiney, S; Sun, W M; Urner, D; Wilksen, T; Weaver, K M; Weinberger, M; Athar, S B; Avery, P; Breva-Newell, L; Patel, R; Potlia, V; Stoeck, H; Yelton, J; Rubin, P; Cawlfield, C; Eisenstein, B I; Gollin, G D; Karliner, I; Kim, D; Lowrey, N; Naik, P; Sedlack, C; Selen, M; White, E J; Williams, J; Wiss, J; Asner, D M; Edwards, K W; Besson, D; Pedlar, T K; Cronin-Hennessy, D; Gao, K Y; Gong, D T; Hietala, J; Kubota, Y; Klein, T; Lang, B W; Li, S Z; Poling, R; Scott, A W; Smith, A; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A; Zweber, P; Ernst, J; Severini, H; Dytman, S A; Love, W; Mehrabyan, S; Mueller, J A; Savinov, V; Li, Z; Lopez, A; Mendez, H; Ramirez, J; Huang, G S; Miller, D H; Pavlunin, V; Sanghi, B; Shipsey, I P J; Adams, G S; Anderson, M; Cummings, J P; Danko, I; Napolitano, J; He, Q; Muramatsu, H; Park, C S; Thorndike, E H; Coan, T E; Gao, Y S; Liu, F; Artuso, M; Boulahouache, C; Blusk, S; Butt, J; Dorjkhaidav, O; Li, J; Menaa, N; Mountain, R; Nandakumar, R; Randrianarivony, K; Redjimi, R; Sia, R; Skwarnicki, T; Stone, S; Wang, J C; Zhang, K; Csorna, S E; Bonvicini, G; Cinabro, D; Dubrovin, M; Briere, R A; Chen, G P; Chen, J; Ferguson, T; Tatishvili, G; Vogel, H; Watkins, M E; Rosner, J L

    2006-03-03

    We observe signals for the decays psi(3770) --> XJ/psi from data acquired with the CLEO detector operating at the CESR e+ e- collider with square root of s = 3773 MeV. We measure the following branching fractions Beta(psi(3770) --> XJ/psi and significances: (189 +/- 20 +/- 20) x 10(-5) (11.6sigma) for X = pi+ pi-, (80 +/- 25 +/- 16) x 10(-5) (3.4sigma) for X = pi0 pi0, and (87 +/- 33 +/- 22) x 10(-5) (3.5sigma) for X = eta, where the errors are statistical and systematic, respectively. The radiative return process e+ e- --> gamma psi(2S) populates the same event sample and is used to measure Gamma ee[psi(2S)] = (2.54 +/- 0.03 +/- 0.11) keV.

  9. Absolute prompt-gamma yield measurements for ion beam therapy monitoring

    NASA Astrophysics Data System (ADS)

    Pinto, M.; Bajard, M.; Brons, S.; Chevallier, M.; Dauvergne, D.; Dedes, G.; De Rydt, M.; Freud, N.; Krimmer, J.; La Tessa, C.; Létang, J. M.; Parodi, K.; Pleskač, R.; Prieels, D.; Ray, C.; Rinaldi, I.; Roellinghoff, F.; Schardt, D.; Testa, E.; Testa, M.

    2015-01-01

    Prompt-gamma emission detection is a promising technique for hadrontherapy monitoring purposes. In this regard, obtaining prompt-gamma yields that can be used to develop monitoring systems based on this principle is of utmost importance since any camera design must cope with the available signal. Herein, a comprehensive study of the data from ten single-slit experiments is presented, five consisting in the irradiation of either PMMA or water targets with lower and higher energy carbon ions, and another five experiments using PMMA targets and proton beams. Analysis techniques such as background subtraction methods, geometrical normalization, and systematic uncertainty estimation were applied to the data in order to obtain absolute prompt-gamma yields in units of prompt-gamma counts per incident ion, unit of field of view, and unit of solid angle. At the entrance of a PMMA target, where the contribution of secondary nuclear reactions is negligible, prompt-gamma counts per incident ion, per millimetre and per steradian equal to (124 ± 0.7stat ± 30sys) × 10-6 for 95 MeV u-1 carbon ions, (79 ± 2stat ± 23sys) × 10-6 for 310 MeV u-1 carbon ions, and (16 ± 0.07stat ± 1sys) × 10-6 for 160 MeV protons were found for prompt gammas with energies higher than 1 MeV. This shows a factor 5 between the yields of two different ions species with the same range in water (160 MeV protons and 310 MeV u-1 carbon ions). The target composition was also found to influence the prompt-gamma yield since, for 300/310 MeV u-1 carbon ions, a 42% greater yield ((112 ± 1stat ± 22sys) × 10-6 counts ion-1 mm-1 sr-1) was obtained with a water target compared to a PMMA one.

  10. Using Nuclear Magnetic Resonance Spectroscopy for Measuring Ternary Phase Diagrams

    ERIC Educational Resources Information Center

    Woodworth, Jennifer K.; Terrance, Jacob C.; Hoffmann, Markus M.

    2006-01-01

    A laboratory experiment is presented for the upper-level undergraduate physical chemistry curriculum in which the ternary phase diagram of water, 1-propanol and n-heptane is measured using proton nuclear magnetic resonance (NMR) spectroscopy. The experiment builds upon basic concepts of NMR spectral analysis, typically taught in the undergraduate…

  11. Spatially-Scanned Dual Comb Spectroscopy for Atmospheric Measurements

    NASA Astrophysics Data System (ADS)

    Cossel, K.; Waxman, E.; Giorgetta, F.; Cermak, M.; Coddington, I.; Hesselius, D.; Ruben, S.; Swann, W.; Rieker, G. B.; Newbury, N.

    2017-12-01

    Measuring trace gas emissions from sources that are spatially complex and temporally variable, such as leaking natural gas infrastructure, is challenging with current measurement systems. Here, we present a new technique that provides the path-integrated concentrations of multiple gas species between a ground station and a retroreflector mounted on a small quadcopter. Such a system could provide the ability to quantify small area emissions sources as well measure vertical mixing within the boundary layer. The system is based on a near-infrared dual frequency-comb spectroscopy system (DCS) covering 1.58-1.7 microns, which enables rapid, accurate measurements of CO2, CH4, H2O, and HDO. The eye-safe laser light is launched from a telescope on a fast azimuth, elevation gimbal to a small quadcopter carrying a lightweight retroreflector as well as a high-precision real-time kinematic GPS receiver (for real-time cm-level path length measurements) and pressure, temperature and humidity sensors. Here, we show the results of test measurements from controlled releases of CH4 as well as from test vertical profiles.

  12. Low gamma counting for measuring NORM/TENORM with a radon reducing system

    NASA Astrophysics Data System (ADS)

    Paschoa, Anselmo S.

    2001-06-01

    A detection system for counting low levels of gamma radiation was built by upgrading an existing rectangular chamber made of 18 metric tonne of steel fabricated before World War II. The internal walls, the ceiling, and the floor of the chamber are covered with copper sheets. The new detection system consists of a stainless steel hollow cylinder with variable circular apertures in the cylindrical wall and in the base, to allow introduction of a NaI (Tl) crystal, or alternatively, a HPGe detector in its interior. This counting system is mounted inside the larger chamber, which in turn is located in a subsurface air-conditioned room. The access to the subsurface room is made from a larger entrance room through a tunnel plus a glass anteroom to decrease the air-exchange rate. Both sample and detector are housed inside the stainless steel cylinder. This cylinder is filled with hyper pure nitrogen gas, before counting a sample, to prevent radon coming into contact with the detector surface. As a consequence, the contribution of the 214Bi photopeaks to the background gamma spectra is minimized. The reduction of the gamma radiation background near the detector facilitates measurement of naturally occurring radioactive materials (NORM), and/or technologically enhanced NORM (TENORM), which are usually at concentration levels only slightly higher than those typically found in the natural radioactive background.

  13. Some gamma-ray shielding measurements made at altitudes greater than 115000 feet using large Ge(Li) detectors

    NASA Technical Reports Server (NTRS)

    Chapman, G. T.; Cumby, R. P.; Gibbons, J. H.; Macklin, R. L.; Parker, H. W.

    1972-01-01

    A series of balloon-flight experiments at altitudes greater than 115,000 feet were conducted to gain information relative to the use of composite shields (passive and/or active) for shielding large-volume, lithium-drifted, germanium (Ge(Li)) detectors used in gamma-ray spectrometers. Data showing the pulse-height spectra of the environmental gamma radiation as measured at 5.3 and 3.8 gms sq cm residual atmosphere with an unshielded diode detector are also presented.

  14. Influence of gamma irradiation on carbon nanotube-reinforced polypropylene.

    PubMed

    Castell, P; Medel, F J; Martinez, M T; Puértolas, J A

    2009-10-01

    Single walled carbon nanotubes (SWNT) have been incorporated into a polypropylene (PP) matrix in different concentrations (range: 0.25-2.5 wt%). The nanotubes were blended with PP particles (approximately 500 microm in size) before mixing in an extruder. Finally, rectangular plates were obtained by compression moulding. PP-SWNT composites were gamma irradiated at different doses, 10 and 20 kGy, to promote crosslinking in the matrix and potentially enhance the interaction between nanotubes and PP. Extensive thermal, structural and mechanical characterization was conducted by means of DSC, X-ray diffraction, Raman spectroscopy, uniaxial tensile tests and dynamic mechanical thermal (DMTA) techniques. DSC thermograms reflected higher crystallinity with increasing nanotube concentration. XRD analysis confirmed the only presence of a monoclinic crystals and proved unambiguously that CNTs generated a preferred orientation. Raman spectroscopy confirmed that the intercalation of the polymer between bundles is favored at low CNTs contents. Elastic modulus results confirmed the reinforcement of the polypropylene matrix with increasing SWNT concentration, although stiffness saturation was observed at the highest concentration. Loss tangent DMTA curves showed three transitions for raw polypropylene. While gamma relaxation remained practically unchanged in all the samples, beta relaxation temperatures showed an increase with increasing CNT content due to the reduced mobility of the system. Gamma-irradiated PP exhibited an increase in the beta relaxation temperature, associated with changes in glass transition due to radiation-induced crosslinking. On the contrary, gamma-irradiated nanocomposites did not show this effect probably due to the reaction of radiative free radicals with CNTs.

  15. Statistical Analysis of Bending Rigidity Coefficient Determined Using Fluorescence-Based Flicker-Noise Spectroscopy.

    PubMed

    Doskocz, Joanna; Drabik, Dominik; Chodaczek, Grzegorz; Przybyło, Magdalena; Langner, Marek

    2018-06-01

    Bending rigidity coefficient describes propensity of a lipid bilayer to deform. In order to measure the parameter experimentally using flickering noise spectroscopy, the microscopic imaging is required, which necessitates the application of giant unilamellar vesicles (GUV) lipid bilayer model. The major difficulty associated with the application of the model is the statistical character of GUV population with respect to their size and the homogeneity of lipid bilayer composition, if a mixture of lipids is used. In the paper, the bending rigidity coefficient was measured using the fluorescence-enhanced flicker-noise spectroscopy. In the paper, the bending rigidity coefficient was determined for large populations of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine vesicles. The quantity of obtained experimental data allows to perform statistical analysis aiming at the identification of the distribution, which is the most appropriate for the calculation of the value of the membrane bending rigidity coefficient. It has been demonstrated that the bending rigidity coefficient is characterized by an asymmetrical distribution, which is well approximated with the gamma distribution. Since there are no biophysical reasons for that we propose to use the difference between normal and gamma fits as a measure of the homogeneity of vesicle population. In addition, the effect of a fluorescent label and types of instrumental setups on determined values has been tested. Obtained results show that the value of the bending rigidity coefficient does not depend on the type of a fluorescent label nor on the type of microscope used.

  16. Comparison of modeled and measured performance of a GSO crystal as gamma detector

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Parno, Diana Syemour; Friend, Megan Lynn; Mamyan, Vahe

    2013-11-01

    We have modeled, tested, and installed a large, cerium-activated Gd{sub 2}SiO{sub 5} crystal scintillator for use as a detector of gamma rays. We present the measured detector response to two types of incident photons: nearly monochromatic photons up to 40 MeV, and photons from a continuous Compton backscattering spectrum up to 200 MeV. Our GEANT4 simulations, developed to determine the analyzing power of the Compton polarimeter in Hall A of Jefferson Lab, reproduce the measured spectra well.

  17. Impact of Image Noise on Gamma Index Calculation

    NASA Astrophysics Data System (ADS)

    Chen, M.; Mo, X.; Parnell, D.; Olivera, G.; Galmarini, D.; Lu, W.

    2014-03-01

    Purpose: The Gamma Index defines an asymmetric metric between the evaluated image and the reference image. It provides a quantitative comparison that can be used to indicate sample-wised pass/fail on the agreement of the two images. The Gamma passing/failing rate has become an important clinical evaluation tool. However, the presence of noise in the evaluated and/or reference images may change the Gamma Index, hence the passing/failing rate, and further, clinical decisions. In this work, we systematically studied the impact of the image noise on the Gamma Index calculation. Methods: We used both analytic formulation and numerical calculations in our study. The numerical calculations included simulations and clinical images. Three different noise scenarios were studied in simulations: noise in reference images only, in evaluated images only, and in both. Both white and spatially correlated noises of various magnitudes were simulated. For clinical images of various noise levels, the Gamma Index of measurement against calculation, calculation against measurement, and measurement against measurement, were evaluated. Results: Numerical calculations for both the simulation and clinical data agreed with the analytic formulations, and the clinical data agreed with the simulations. For the Gamma Index of measurement against calculation, its distribution has an increased mean and an increased standard deviation as the noise increases. On the contrary, for the Gamma index of calculation against measurement, its distribution has a decreased mean and stabilized standard deviation as the noise increases. White noise has greater impact on the Gamma Index than spatially correlated noise. Conclusions: The noise has significant impact on the Gamma Index calculation and the impact is asymmetric. The Gamma Index should be reported along with the noise levels in both reference and evaluated images. Reporting of the Gamma Index with switched roles of the images as reference and

  18. Z{gamma}{gamma}{gamma} {yields} 0 Processes in SANC

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bardin, D. Yu., E-mail: bardin@nu.jinr.ru; Kalinovskaya, L. V., E-mail: kalinov@nu.jinr.ru; Uglov, E. D., E-mail: corner@nu.jinr.ru

    2013-11-15

    We describe the analytic and numerical evaluation of the {gamma}{gamma} {yields} {gamma}Z process cross section and the Z {yields} {gamma}{gamma}{gamma} decay rate within the SANC system multi-channel approach at the one-loop accuracy level with all masses taken into account. The corresponding package for numeric calculations is presented. For checking of the results' correctness we make a comparison with the other independent calculations.

  19. Formation of gamma(sup prime)-Ni3Al via the Peritectoid Reaction: gamma + beta (+ Al2O3)=gamma(sup prime)(+ Al2O3)

    NASA Technical Reports Server (NTRS)

    Copeland, Evan

    2008-01-01

    The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8-32 at.%Al and temperature range T=1400-1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma(sup prime)-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3)=gamma + Beta(+ Al2O3), at 1640 +/- 1 K and a liquid composition of 24.8 +/- 0.2 at.%al (at an unknown oxygen content). The {gamma + Beta (+Al2O3} phase field is stable over the temperature range 1633-1640 K, and gamma(sup prime)-Ni3Al forms via the peritectoid, gamma + Beta (+ Al2O3)=gamma(sup prime) (+ Al2O3), at 1633 +/- 1 K. This behavior is consistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady-state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma(sup prime)-Ni2Al phase field.

  20. Sneaky Gamma-Rays: Using Gravitational Lensing to Avoid Gamma-Gamma-Absorption

    NASA Astrophysics Data System (ADS)

    Boettcher, Markus; Barnacka, Anna

    2014-08-01

    It has recently been suggested that gravitational lensing studies of gamma-ray blazars might be a promising avenue to probe the location of the gamma-ray emitting region in blazars. Motivated by these prospects, we have investigated potential gamma-gamma absorption signatures of intervening lenses in the very-high-energy gamma-ray emission from lensedblazars. We considered intervening galaxies and individual stars within these galaxies. We find that the collective radiation field of galaxies acting as sources of macrolensing are not expected to lead to significant gamma-gamma absorption. Individual stars within intervening galaxies could, in principle, cause a significant opacity to gamma-gamma absorption for VHE gamma-rays if the impact parameter (the distance of closest approach of the gamma-ray to the center of the star) is small enough. However, we find that the curvature of the photon path due to gravitational lensing will cause gamma-ray photons to maintain a sufficiently large distance from such stars to avoid significant gamma-gamma absorption. This re-inforces the prospect of gravitational-lensing studies of gamma-ray blazars without interference due to gamma-gamma absorption due to the lensing objects.

  1. High-resolution imaging gamma-ray spectroscopy with externally segmented germanium detectors

    NASA Technical Reports Server (NTRS)

    Callas, J. L.; Mahoney, W. A.; Varnell, L. S.; Wheaton, W. A.

    1993-01-01

    Externally segmented germanium detectors promise a breakthrough in gamma-ray imaging capabilities while retaining the superb energy resolution of germanium spectrometers. An angular resolution of 0.2 deg becomes practical by combining position-sensitive germanium detectors having a segment thickness of a few millimeters with a one-dimensional coded aperture located about a meter from the detectors. Correspondingly higher angular resolutions are possible with larger separations between the detectors and the coded aperture. Two-dimensional images can be obtained by rotating the instrument. Although the basic concept is similar to optical or X-ray coded-aperture imaging techniques, several complicating effects arise because of the penetrating nature of gamma rays. The complications include partial transmission through the coded aperture elements, Compton scattering in the germanium detectors, and high background count rates. Extensive electron-photon Monte Carlo modeling of a realistic detector/coded-aperture/collimator system has been performed. Results show that these complicating effects can be characterized and accounted for with no significant loss in instrument sensitivity.

  2. A novel fibrinogen variant--Praha I: hypofibrinogenemia associated with gamma Gly351Ser substitution.

    PubMed

    Kotlín, Roman; Chytilová, Martina; Suttnar, Jirí; Salaj, Peter; Riedel, Tomás; Santrůcek, Jirí; Klener, Pavel; Dyr, Jan Evangelista

    2007-05-01

    A 25-yr-old man from Prague had abnormal bleeding after several surgical operations with low fibrinogen level and hypofibrinogenemia was suspected. The patient, 25 yr-old male had a low fibrinogen concentration as determined by the thrombin time and immunoturbidimetrical method. His 48-yr-old mother presented with normal coagulation tests, normal fibrinogen level and reported no history of bleeding. To identify the genetic mutation responsible for this hypofibrinogen, genomic DNA extracted from the blood was analyzed. Fibrin polymerization measurement, kinetics of fibrinopeptide release, fibrinogen clottability measurement, mass spectroscopy, and scanning electron microscopy were performed. DNA sequencing showed heterogeneous fibrinogen gammaG351S mutation in the propositus. The mutant chain was found not to be expressed to the circulation by matrix-assisted laser desorption/ionization time of flight mass spectrometry. Scanning electron micrographs of the patient's fibrin clot as well as kinetics of fibrinopeptide release and fibrin polymerization were found to be normal. A case of hypofibrinogenemia gammaG351S was found by routine coagulation testing and was genetically identified.

  3. 102Pd(n, {gamma}) Cross Section Measurement Using DANCE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hatarik, R.; Alpizar-Vicente, A. M.; Los Alamos National Laboratory, Los Alamos, NM 87545

    2006-03-13

    The neutron capture cross section of the proton rich nucleus 102Pd was measured with the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center. The target was a 2 mg Pd foil with 78% enriched 102Pd. It was held by a 0.9 {mu}m thick Mylar bag which was selected after comparing different thicknesses of Kapton and Mylar for their scattering background. To identify the contribution of the other Pd isotopes the data of a natural Pd sample was compared to the data of the 102Pd enriched sample. A 12C sample was used to determine themore » scattering background. The 102Pd(n, {gamma}) rate is of importance for the p-process nucleosynthesis.« less

  4. Light Source Effects on Aerosol Photoacoustic Spectroscopy Measurements

    PubMed Central

    Radney, James G.; Zangmeister, Christopher D.

    2016-01-01

    Photoacoustic spectroscopy measurements of flame-generated soot aerosol coated with small amounts of water yielded absorption enhancements that were dependent on the laser used: quasi-continuous wave (Q-CW, ≈ 650 ps pulse duration and 78 MHz repetition rate) versus continuous wave (CW). Water coating thickness was controlled by exposing the aerosol to a set relative humidity (RH). At ≈ 85 % RH, the mass of the soot particles increased by an amount comparable to a monolayer of water being deposited and enhanced the measured absorption by 36 % and 15 % for the Q-CW and CW lasers, respectively. Extinction measurements were also performed using a cavity ring-down spectrometer (extinction equals the sum of absorption and scattering) with a CW laser and negligible enhancement was observed at all RH. These findings demonstrate that source choice can impact measurements of aerosols with volatile coatings and that the absorption enhancements at high RH previously measured by Radney and Zangmeister (2015) [1] are the result of laser source used (Q-CW) and not from an increase in the particle absorption cross section. PMID:28066027

  5. Comparison of gamma densitometry and electrical capacitance measurements applied to hold-up prediction of oil–water flow patterns in horizontal and slightly inclined pipes

    NASA Astrophysics Data System (ADS)

    Perera, Kshanthi; Kumara, W. A. S.; Hansen, Fredrik; Mylvaganam, Saba; Time, Rune W.

    2018-06-01

    Measurement techniques are vital for the control and operation of multiphase oil–water flow in pipes. The development of such techniques depends on laboratory experiments involving flow visualization, liquid fraction (‘hold-up’), phase slip and pressure drop measurements. They provide valuable information by revealing the physics, spatial and temporal structures of complex multiphase flow phenomena. This paper presents the hold-up measurement of oil–water flow in pipelines using gamma densitometry and electrical capacitance tomography (ECT) sensors. The experiments were carried out with different pipe inclinations from  ‑5° to  +6° for selected mixture velocities (0.2–1.5 m s‑1), and at selected watercuts (0.05–0.95). Mineral oil (Exxsol D60) and water were used as test fluids. Nine flow patterns were identified including a new pattern called stratified wavy and mixed interface flow. As a third direct method, visual observations and high-speed videos were used for the flow regime and interface identification. ECT and gamma densitometry hold-up measurements show similar trends for changes in pipeline inclinations. Changing the pipe inclination affected the flow mostly at lower mixture velocities and caused a change of flow patterns, allowing the highest change of hold-up. ECT hold-up measurements overpredict the gamma densitometry measurements at higher input water cuts and underpredict at intermediate water cuts. Gamma hold-up results showed good agreement with the literature results, having a maximum deviation of 6%, while it was as high as 22% for ECT in comparison to gamma densitometry. Uncertainty analysis of the measurement techniques was carried out with single-phase oil flow. This shows that the measurement error associated with gamma densitometry is approximately 3.2%, which includes 1.3% statistical error and 2.9% error identified as electromagnetically induced noise in electronics. Thus, gamma densitometry can predict hold

  6. First neutron spectroscopy measurements with a pixelated diamond detector at JET

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Muraro, A., E-mail: muraro@ifp.cnr.it; Giacomelli, L.; Grosso, G.

    2016-11-15

    A prototype Single crystal Diamond Detector (SDD) was installed at the Joint European Torus (JET) in 2013 along an oblique line of sight and demonstrated the possibility to carry out neutron spectroscopy measurements with good energy resolution and detector stability in discharges heated by neutral beam injection and radio-frequency waves. Starting from these positive results, within the Vertical Neutron Spectrometer project of the Joint European Torus, we have developed a pixelated instrument consisting of a matrix of 12 independent SDDs, called the Diamond Vertical Neutron Spectrometer (DVNS), which boosts the detection efficiency of a single SDD by an order ofmore » magnitude. In this paper we describe the main features of the DVNS, including the detector design, energy resolution, and data acquisition system for on-line processing. Preliminary spectroscopy measurements of 2.5 MeV neutrons from the present deuterium plasma at JET are finally presented.« less

  7. First neutron spectroscopy measurements with a pixelated diamond detector at JET.

    PubMed

    Muraro, A; Giacomelli, L; Nocente, M; Rebai, M; Rigamonti, D; Belli, F; Calvani, P; Figueiredo, J; Girolami, M; Gorini, G; Grosso, G; Murari, A; Popovichev, S; Trucchi, D M; Tardocchi, M

    2016-11-01

    A prototype Single crystal Diamond Detector (SDD) was installed at the Joint European Torus (JET) in 2013 along an oblique line of sight and demonstrated the possibility to carry out neutron spectroscopy measurements with good energy resolution and detector stability in discharges heated by neutral beam injection and radio-frequency waves. Starting from these positive results, within the Vertical Neutron Spectrometer project of the Joint European Torus, we have developed a pixelated instrument consisting of a matrix of 12 independent SDDs, called the Diamond Vertical Neutron Spectrometer (DVNS), which boosts the detection efficiency of a single SDD by an order of magnitude. In this paper we describe the main features of the DVNS, including the detector design, energy resolution, and data acquisition system for on-line processing. Preliminary spectroscopy measurements of 2.5 MeV neutrons from the present deuterium plasma at JET are finally presented.

  8. Scientific prospects for spectroscopy of the gamma-ray burst prompt emission with SVOM

    NASA Astrophysics Data System (ADS)

    Bernardini, M. G.; Xie, F.; Sizun, P.; Piron, F.; Dong, Y.; Atteia, J.-L.; Antier, S.; Daigne, F.; Godet, O.; Cordier, B.; Wei, J.

    2017-10-01

    SVOM (Space-based multi-band astronomical Variable Objects Monitor) is a Sino-French space mission dedicated to the study of Gamma-Ray Bursts (GRBs) in the next decade, capable to detect and localise the GRB emission, and to follow its evolution in the high-energy and X-ray domains, and in the visible and NIR bands. The satellite carries two wide-field high-energy instruments: a coded-mask gamma-ray imager (ECLAIRs; 4-150 keV), and a gamma-ray spectrometer (GRM; 15-5500 keV) that, together, will characterise the GRB prompt emission spectrum over a wide energy range. In this paper we describe the performances of the ECLAIRs and GRM system with different populations of GRBs from existing catalogues, from the classical ones to those with a possible thermal component superimposed to their non-thermal emission. The combination of ECLAIRs and the GRM will provide new insights also on other GRB properties, as for example the spectral characterisation of the subclass of short GRBs showing an extended emission after the initial spike.

  9. A Gamma Polarimeter for Neutron Polarization Measurement in a Liquid Deuterium Target for Parity Violation in Polarized Neutron Capture on Deuterium.

    PubMed

    Komives, A; Sint, A K; Bowers, M; Snow, M

    2005-01-01

    A measurement of the parity-violating gamma asymmetry in n-D capture would yield information on N-N parity violation independent of the n-p system. Since cold neutrons will depolarize in a liquid deuterium target in which the scattering cross section is much larger than the absorption cross section, it will be necessary to quantify the loss of polarization before capture. One way to do this is to use the large circular polarization of the gamma from n-D capture and analyze the circular polarization of the gamma in a gamma polarimeter. We describe the design of this polarimeter.

  10. Use of carborne measured gamma-ray K/Th ratio for estimation of texture at different field sites across Europe

    NASA Astrophysics Data System (ADS)

    Dierke, C.; Werban, U.; Dietrich, P.

    2011-12-01

    In the past gamma-ray measurements were used for geological survey from aircraft and in borehole logging for deposit exploration and geological survey. For these applications the relationships between the physical measured parameter - the concentration of natural gamma emitter 40K, 238U and 232Th - and geological origin or sedimentary developments are described well. Based on these applications and knowledge in combination with adjusted sensor systems, gamma-ray measurements seem to be also a useful and fast tool for soil characterization. The measured isotope concentration in soils depends on different soil parameters, which are the result of composition and properties of parent rock and processes during soil geneses under different climatic conditions. Grain size distribution, type of clay minerals and organic matter are soil parameters which influence the gamma-ray concentration directly. Many applications of gamma-ray measurements for soil characterisation and digital soil mapping (DSM) are known from e.g. Australia and during the last years there are attempts to use that method in Europe as well. One main influencing factor for nuclide concentration in soils is the grain size. Megumi (1977) found with decreasing particle size an increase in nuclide concentration, which can be explained by higher specific surface and resulting higher surface adsorption for smaller particles. We did systematic measurements at different field sites across Central Europe to investigate the relationship between concentration of gamma emitter and the grain size distribution of top soil. For the measurements we choose field sites with different pedogenesis and range in clay content. For survey we used a 4l NaI(Tl) detector, which is mounted on a sledge an can be towed by a four-wheel-vehicle across the agricultural used field sites. The measured nuclide concentrations were compared with grain size distribution data of fine soil (< 2 mm). For interpretation we used single nuclide

  11. System of Programmed Modules for Measuring Photographs with a Gamma-Telescope

    NASA Technical Reports Server (NTRS)

    Averin, S. A.; Veselova, G. V.; Navasardyan, G. V.

    1978-01-01

    Physical experiments using tracking cameras resulted in hundreds of thousands of stereo photographs of events being received. To process such a large volume of information, automatic and semiautomatic measuring systems are required. At the Institute of Space Research of the Academy of Science of the USSR, a system for processing film information from the spark gamma-telescope was developed. The system is based on a BPS-75 projector in line with the minicomputer Elektronika 1001. The report describes this system. The various computer programs available to the operators are discussed.

  12. TL detectors for gamma ray dose measurements in criticality accidents.

    PubMed

    Miljanić, Saveta; Zorko, Benjamin; Gregori, Beatriz; Knezević, Zeljka

    2007-01-01

    Determination of gamma ray dose in mixed neutron+gamma ray fields is still a demanding task. Dosemeters used for gamma ray dosimetry are usually in some extent sensitive to neutrons and their response variations depend on neutron energy i.e., on neutron spectra. Besides, it is necessary to take into account the energy dependence of dosemeter responses to gamma rays. In this work, several types of thermoluminescent detectors (TLD) placed in different holders used for gamma ray dose determination in the mixed fields were examined. Dosemeters were from three different institutions: Ruder Bosković Institute (RBI), Croatia, JoZef Stefan Institute (JSI), Slovenia and Autoridad Regulatoria Nuclear (ARN), Argentina. All dosemeters were irradiated during the International Intercomparison of Criticality Accident Dosimetry Systems at the SILENE Reactor, Valduc, June 2002. Three accidental scenarios were reproduced and in each irradiation the dosemeters were exposed placed on the front of phantom and 'free in air'. Following types of TLDs were used: 7LiF (TLD-700), CaF2:Mn and Al2O3:Mg,Y-all from RBI; CaF2:Mn from JSI and 7LiF (TLD-700) from ARN. Reported doses were compared with the reference values as well as with the values obtained from the results of all participants. The results show satisfactory agreement with other dosimetry systems used in the Intercomparison. The influence of different types of holders and applied corrections of dosemeters' readings are discussed.

  13. Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.

    1992-01-01

    The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1,2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

  14. First results of electron temperature measurements by the use of multi-pass Thomson scattering system in GAMMA 10

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yoshikawa, M., E-mail: yosikawa@prc.tsukuba.ac.jp; Nagasu, K.; Shimamura, Y.

    2014-11-15

    A multi-pass Thomson scattering (TS) has the advantage of enhancing scattered signals. We constructed a multi-pass TS system for a polarisation-based system and an image relaying system modelled on the GAMMA 10 TS system. We undertook Raman scattering experiments both for the multi-pass setting and for checking the optical components. Moreover, we applied the system to the electron temperature measurements in the GAMMA 10 plasma for the first time. The integrated scattering signal was magnified by approximately three times by using the multi-pass TS system with four passes. The electron temperature measurement accuracy is improved by using this multi-pass system.

  15. First results of electron temperature measurements by the use of multi-pass Thomson scattering system in GAMMA 10.

    PubMed

    Yoshikawa, M; Yasuhara, R; Nagasu, K; Shimamura, Y; Shima, Y; Kohagura, J; Sakamoto, M; Nakashima, Y; Imai, T; Ichimura, M; Yamada, I; Funaba, H; Kawahata, K; Minami, T

    2014-11-01

    A multi-pass Thomson scattering (TS) has the advantage of enhancing scattered signals. We constructed a multi-pass TS system for a polarisation-based system and an image relaying system modelled on the GAMMA 10 TS system. We undertook Raman scattering experiments both for the multi-pass setting and for checking the optical components. Moreover, we applied the system to the electron temperature measurements in the GAMMA 10 plasma for the first time. The integrated scattering signal was magnified by approximately three times by using the multi-pass TS system with four passes. The electron temperature measurement accuracy is improved by using this multi-pass system.

  16. Kosmos 856 and Kosmos 914 measurements of high-energy diffuse gamma rays

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kalinkin, L.F.; Nagornykh, Y.I.

    1982-09-01

    The measurements by the Kosmos 856 and Kosmos 914 satellites of diffuse cosmic ..gamma.. rays with photon energies above 100 MeV are discussed. Integrated energy spectra for the 100--4000 MeV energy range are given for galactic lattitudes Vertical BarbVertical Bar< or =30/sup 0/ and Vertical BarbVertical Bar>30/sup 0/. The form of the spectra suggests that at high lattitudes there may still be some contribution from the galactic component.

  17. Elevated gamma-aminobutyric acid levels in chronic schizophrenia.

    PubMed

    Ongür, Dost; Prescot, Andrew P; McCarthy, Julie; Cohen, Bruce M; Renshaw, Perry F

    2010-10-01

    Despite widely replicated abnormalities of gamma-aminobutyric acid (GABA) neurons in schizophrenia postmortem, few studies have measured tissue GABA levels in vivo. We used proton magnetic resonance spectroscopy to measure tissue GABA levels in participants with schizophrenia and healthy control subjects in the anterior cingulate cortex and parieto-occipital cortex. Twenty-one schizophrenia participants effectively treated on a stable medication regimen (mean age 39.0, 14 male) and 19 healthy control subjects (mean age 36.3, 12 male) underwent a proton magnetic resonance spectroscopy scan using GABA-selective editing at 4 Tesla after providing informed consent. Data were collected from two 16.7-mL voxels and analyzed using LCModel. We found elevations in GABA/creatine in the schizophrenia group compared with control subjects [F(1,65) = 4.149, p = .046] in both brain areas (15.5% elevation in anterior cingulate cortex, 11.9% in parieto-occipital cortex). We also found a positive correlation between GABA/creatine and glutamate/creatine, which was not accounted for by % GM or brain region. We found elevated GABA/creatinine in participants with chronically treated schizophrenia. Postmortem studies report evidence for dysfunctional GABAergic neurotransmission in schizophrenia. Elevated GABA levels, whether primary to illness or compensatory to another process, may be associated with dysfunctional GABAergic neurotransmission in chronic schizophrenia. Copyright © 2010 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  18. Monte Carlo simulation of gamma-ray interactions in an over-square high-purity germanium detector for in-vivo measurements

    NASA Astrophysics Data System (ADS)

    Saizu, Mirela Angela

    2016-09-01

    The developments of high-purity germanium detectors match very well the requirements of the in-vivo human body measurements regarding the gamma energy ranges of the radionuclides intended to be measured, the shape of the extended radioactive sources, and the measurement geometries. The Whole Body Counter (WBC) from IFIN-HH is based on an “over-square” high-purity germanium detector (HPGe) to perform accurate measurements of the incorporated radionuclides emitting X and gamma rays in the energy range of 10 keV-1500 keV, under conditions of good shielding, suitable collimation, and calibration. As an alternative to the experimental efficiency calibration method consisting of using reference calibration sources with gamma energy lines that cover all the considered energy range, it is proposed to use the Monte Carlo method for the efficiency calibration of the WBC using the radiation transport code MCNP5. The HPGe detector was modelled and the gamma energy lines of 241Am, 57Co, 133Ba, 137Cs, 60Co, and 152Eu were simulated in order to obtain the virtual efficiency calibration curve of the WBC. The Monte Carlo method was validated by comparing the simulated results with the experimental measurements using point-like sources. For their optimum matching, the impact of the variation of the front dead layer thickness and of the detector photon absorbing layers materials on the HPGe detector efficiency was studied, and the detector’s model was refined. In order to perform the WBC efficiency calibration for realistic people monitoring, more numerical calculations were generated simulating extended sources of specific shape according to the standard man characteristics.

  19. Effects of Correlated and Uncorrelated Gamma Rays on Neutron Multiplicity Counting

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cowles, Christian C.; Behling, Richard S.; Imel, George R.

    Neutron multiplicity counting relies on time correlation between neutron events to assay the fissile mass, (α,n) to spontaneous fission neutron ratio, and neutron self-multiplication of samples. Gamma-ray sensitive neutron multiplicity counters may misidentify gamma rays as neutrons and therefore miscalculate sample characteristics. Time correlated and uncorrelated gamma-ray-like signals were added into gamma-ray free neutron multiplicity counter data to examine the effects of gamma ray signals being misidentified as neutron signals on assaying sample characteristics. Multiplicity counter measurements with and without gamma-ray-like signals were compared to determine the assay error associated with gamma-ray-like signals at various gamma-ray and neutron rates. Correlatedmore » and uncorrelated gamma-ray signals each produced consistent but different measurement errors. Correlated gamma-ray signals most strongly led to fissile mass overestimates, whereas uncorrelated gamma-ray signals most strongly lead to (α,n) neutron overestimates. Gamma-ray sensitive neutron multiplicity counters may be able to account for the effects of gamma-rays on measurements to mitigate measurement uncertainties.« less

  20. Atmospheric Measurements by Cavity Enhanced Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yi, Hongming; Wu, Tao; Coeur-Tourneur, Cécile; Fertein, Eric; Gao, Xiaoming; Zhao, Weixiong; Zhang, Weijun; Chen, Weidong

    2015-04-01

    Since the last decade, atmospheric environmental monitoring has benefited from the development of novel spectroscopic measurement techniques owing to the significant breakthroughs in photonic technology from the UV to the infrared spectral domain [1]. In this presentation, we will overview our recent development and applications of cavity enhanced absorption spectroscopy techniques for in situ optical monitoring of chemically reactive atmospheric species (such as HONO, NO3, NO2, N2O5) in intensive campaigns [2] and/or in smog chamber studies [3]. These field deployments demonstrated that modern photonic technologies (newly emergent light sources combined with high sensitivity spectroscopic techniques) can provide a useful tool to improve our understanding of tropospheric chemical processes which affect climate, air quality, and the spread of pollution. Experimental detail and preliminary results will be presented. Acknowledgements. The financial support from the French Agence Nationale de la Recherche (ANR) under the NexCILAS (ANR-11-NS09-0002) and the CaPPA (ANR-10-LABX-005) contracts is acknowledged. References [1] X. Cui, C. Lengignon, T. Wu, W. Zhao, G. Wysocki, E. Fertein, C. Coeur, A. Cassez,L. Croisé, W. Chen, et al., "Photonic Sensing of the Atmosphere by absorption spectroscopy", J. Quant. Spectrosc. Rad. Transfer 113 (2012) 1300-1316 [2] T. Wu, Q. Zha, W. Chen, Z. XU, T. Wang, X. He, "Development and deployment of a cavity enhanced UV-LED spectrometer for measurements of atmospheric HONO and NO2 in Hong Kong", Atmos. Environ. 95 (2014) 544-551 [3] T. Wu, C. Coeur-Tourneur, G. Dhont,A. Cassez, E. Fertein, X. He, W. Chen,"Application of IBBCEAS to kinetic study of NO3 radical formation from O3 + NO2 reaction in an atmospheric simulation chamber", J. Quant. Spectrosc. Rad. Transfer 133 (2014)199-205

  1. Fermi GBM Observations of Terrestrial Gamma Flashes

    NASA Technical Reports Server (NTRS)

    Wilson-Hodge, Colleen A.; Briggs, M. S.; Fishman, G. J.; Bhat, P. N.; Paciesas, W. S.; Preece, R.; Kippen, R. M.; von Kienlin, A.; Dwyer, J. R.; Smith, D. M.; hide

    2010-01-01

    In its first two years of operation, the Fermi Gamma Ray Burst Monitor (GBM) has observed more than 77 Terrestrial Gamma Flashes (TGFs). The thick Bismuth Germanate (BGO) detectors are excellent for TGF spectroscopy, having a high probability of recording the full energy of an incident photon, spanning a broad energy range from 150 keV to 40 MeV, and recording a large number of photons per TGF. Correlations between GBM TGF triggers and lightning sferics detected with the World-Wide Lightning Location Network indicate that TGFs and lightning are simultaneous to within tens of microseconds. The energy spectra of some TGFs have strong 511 keV positron annihilation lines, indicating that these TGFs contain a large fraction of positrons

  2. Measuring the Earth System in a Time of Global Environmental Change with Image Spectroscopy

    NASA Technical Reports Server (NTRS)

    Green, Robert O.

    2005-01-01

    Measuring the Earth system in a time of global environmental change. Imaging Spectroscopy enables remote measurement. Remote Measurement determination of the properties of the Earth's surface and atmosphere through the physics, chemistry and biology of the interaction of electromagnetic energy with matter.

  3. Performance of the prototype LaBr{sub 3} spectrometer developed for the JET gamma-ray camera upgrade

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rigamonti, D., E-mail: davide.rigamonti@mib.infn.it; Nocente, M.; Gorini, G.

    2016-11-15

    In this work, we describe the solution developed by the gamma ray camera upgrade enhancement project to improve the spectroscopic properties of the existing JET γ-ray camera. Aim of the project is to enable gamma-ray spectroscopy in JET deuterium-tritium plasmas. A dedicated pilot spectrometer based on a LaBr{sub 3} crystal coupled to a silicon photo-multiplier has been developed. A proper pole zero cancellation network able to shorten the output signal to a length of 120 ns has been implemented allowing for spectroscopy at MHz count rates. The system has been characterized in the laboratory and shows an energy resolution ofmore » 5.5% at E{sub γ} = 0.662 MeV, which extrapolates favorably in the energy range of interest for gamma-ray emission from fast ions in fusion plasmas.« less

  4. Assessment of ambient gamma dose rate around a prospective uranium mining area of South India - A comparative study of dose by direct methods and soil radioactivity measurements

    NASA Astrophysics Data System (ADS)

    Karunakara, N.; Yashodhara, I.; Sudeep Kumara, K.; Tripathi, R. M.; Menon, S. N.; Kadam, S.; Chougaonkar, M. P.

    Indoor and outdoor gamma dose rates were evaluated around a prospective uranium mining region - Gogi, South India through (i) direct measurements using a GM based gamma dose survey meter, (ii) integrated measurement days using CaSO4:Dy based thermo luminescent dosimeters (TLDs), and (iii) analyses of 273 soil samples for 226Ra, 232Th, and 40K activity concentration using HPGe gamma spectrometry. The geometric mean values of indoor and outdoor gamma dose rates were 104 nGy h-1 and 97 nGy h-1, respectively with an indoor to outdoor dose ratio of 1.09. The gamma dose rates and activity concentrations of 226Ra, 232Th, and 40K varied significantly within a small area due to the highly localized mineralization of the elements. Correlation study showed that the dose estimated from the soil radioactivity is better correlated with that measured directly using the portable survey meter, when compared to that obtained from TLDs. This study showed that in a region having localized mineralization in situ measurements using dose survey meter provide better representative values of gamma dose rates.

  5. Measurements of {Gamma}(Z{sup O} {yields} b{bar b})/{Gamma}(Z{sup O} {yields} hadrons) using the SLD

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Neal, H.A. Jr. II

    1995-07-01

    The quantity R{sub b} = {Gamma}(Z{sup o} {yields}b{bar b})/{Gamma}(Z{sup o} {yields} hadrons) is a sensitive measure of corrections to the Zbb vertex. The precision necessary to observe the top quark mass dependent corrections is close to being achieved. LEP is already observing a 1.8{sigma} deviation from the Standard Model prediction. Knowledge of the top quark mass combined with the observation of deviations from the Standard Model prediction would indicate new physics. Models which include charged Higgs or light SUSY particles yield predictions for R{sub b} appreciably different from the Standard Model. In this thesis two independent methods are used tomore » measure R{sub b}. One uses a general event tag which determines R{sub b} from the rate at which events are tagged as Z{sup o} {yields} b{bar b} in data and the estimated rates at which various flavors of events are tagged from the Monte Carlo. The second method reduces the reliance on the Monte Carlo by separately tagging each hemisphere as containing a b-decay. The rates of single hemisphere tagged events and both hemisphere tagged events are used to determine the tagging efficiency for b-quarks directly from the data thus eliminating the main sources of systematic error present in the event tag. Both measurements take advantage of the unique environment provided by the SLAC Linear Collider (SLC) and the SLAC Large Detector (SLD). From the event tag a result of R{sub b} = 0.230{plus_minus}0.004{sub statistical}{plus_minus}0.013{sub systematic} is obtained. The higher precision hemisphere tag result obtained is R{sub b} = 0.218{plus_minus}0.004{sub statistical}{plus_minus}0.004{sub systematic}{plus_minus}0.003{sub Rc}.« less

  6. Spectral measurements of direct and scattered gamma radiation at a boiling-water reactor site

    NASA Astrophysics Data System (ADS)

    Block, R. C.; Preiss, I. L.; Ryan, R. M.; Vargo, G. J.

    1990-12-01

    Quantitative surveys of direct and scattered gamma radiation emitted from the steam-power conversion systems of a boiling-water reactor and other on-site radiation sources were made using a directionally shielded HPGe gamma spectrometry system. The purpose of this study was to obtain data on the relative contributions and energy distributions of direct and scattered gamma radiation in the site environs. The principal radionuclide of concern in this study is 16N produced by the 16O(n,p) 16N reaction in the reactor coolant. Due to changes in facility operation resulting from the implementation of hydrogen water chemistry (HWC), the amount of 16N transported from the reactor to the main steam system under full power operation is excepted to increase by a factor of 1.2 to 5.0. This increase in the 16N source term in the nuclear steam must be considered in the design of new facilities to be constructed on site as well as the evaluation of existing facilities with repect to ALARA (As Low As Reasonably Achievable) dose limits in unrestricted areas. This study consisted of base-line measurements taken under normal BWR chemistry conditions in October, 1987 and a corresponding set taken under HWC conditions in July, 1988. Ground-level and elevated measurements, corresponding to second-story building height, were obtained. The primary conclusion of this study is that direct radiation from the steam-power conversion system is the predominant source of radiation in the site environs of this reactor and that air scattering (i.e. skyshine) does not appear to be significant.

  7. Measurement of temperature profiles in flames by emission-absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Simmons, F. S.; Arnold, C. B.; Lindquist, G. H.

    1972-01-01

    An investigation was conducted to explore the use of infrared and ultraviolet emission-absorption spectroscopy for determination of temperature profiles in flames. Spectral radiances and absorptances were measured in the 2.7-micron H2O band and the 3064-A OH band in H2/O2 flames for several temperature profiles which were directly measured by a sodium line-reversal technique. The temperature profiles, determined by inversion of the infrared and ultraviolet spectra, showed an average disagreement with line-reversal measurements of 50 K for the infrared and 200 K for the ultraviolet at a temperature of 2600 K. The reasons for these discrepancies are discussed in some detail.

  8. Synthetic Pulse Dilation - PMT Model for high bandwidth gamma measurements

    NASA Astrophysics Data System (ADS)

    Geppert-Kleinrath, H.; Herrmann, H. W.; Kim, Y. H.; Zylstra, A. B.; Meaney, K. D.; Lopez, F. E.; Khater, H.; Horsfield, C. J.; Gales, S.; Leatherland, A.; Hilsabeck, T.; Kilkenny, J. D.; Hares, J. D.; Dymoke-Bradshaw, T.; Milnes, J.

    2017-10-01

    The Cherenkov mechanism used in Gas Cherenkov Detectors (GCD) is exceptionally fast. However, the temporal resolution of GCDs, such as the Gamma Reaction History diagnostic (GRH), is limited by the current state-of-the-art photomultiplier tube (PMT) to 100 ps. The new pulse dilation - PMT (PD-PMT) for NIF allows for a temporal resolution comparable to that of the gas cell, or of 10ps. Enhanced resolution will contribute to the quest for ignition in a crucial way through precision measurement of reaction history and areal density (ρ R) history, leading to better constrained models. Features such as onset of alpha heating, shock reverberations and burn truncation due to dynamically evolving failure modes will become visible for the first time. PD-PMT will be deployed on GCD-3 at NIF in 2018. Our synthetic PD-PMT model evaluates the capabilities of these future measurements, as well as minimum yield requirements for measurements performed in a well at 3.9 m from target chamber center (TCC), and within a diagnostic inserter at 0.2m from TCC.

  9. Radon survey and soil gamma doses in primary schools of Batman, Turkey.

    PubMed

    Damla, Nevzat; Aldemir, Kamuran

    2014-06-01

    A survey was conducted to evaluate levels of indoor radon and gamma doses in 42 primary schools located in Batman, southeastern Anatolia, Turkey. Indoor radon measurements were carried out using CR-39 solid-state nuclear track detector-based radon dosimeters. The overall mean annual (222)Rn activity in the surveyed area was found to be 49 Bq m(-3) (equivalent to an annual effective dose of 0.25 mSv). However, in one of the districts (Besiri) the maximum radon value turned out to be 307 Bq m(-3). The estimated annual effective doses are less than the recommended action level (3-10 mSv). It is found that the radon concentration decreases with increasing floor number. The concentrations of natural and artificial radioisotopes were determined using gamma-ray spectroscopy for soil samples collected in close vicinity of the studied schools. The mean gamma activity concentrations in the soil samples were 31, 25, 329 and 12 Bq kg(-1) for (226)Ra, (232)Th, (40)K and (137)Cs, respectively. The radiological parameters such as the absorbed dose rate in air and the annual effective dose equivalent were calculated. These radiological parameters were evaluated and compared with the internationally recommended values.

  10. Measurement of electron paramagnetic resonance using terahertz time-domain spectroscopy.

    PubMed

    Kozuki, Kohei; Nagashima, Takeshi; Hangyo, Masanori

    2011-12-05

    We present a frequency-domain electron spin resonance (ESR) measurement system using terahertz time-domain spectroscopy. A crossed polarizer technique is utilized to increase the sensitivity in detecting weak ESR signals of paramagnets caused by magnetic dipole transitions between magnetic sublevels. We demonstrate the measurements of ESR signal of paramagnetic copper(II) sulfate pentahydrate with uniaxial anisotropy of the g-factor under magnetic fields up to 10 T. The lineshape of the obtained ESR signals agrees well with the theoretical predictions for a powder sample with the uniaxial anisotropy.

  11. Is bone mineral density measurement using dual-energy X-ray absorptiometry affected by gamma rays?

    PubMed

    Xie, Liang-Jun; Li, Jian-Fang; Zeng, Feng-Wei; Jiang, Hang; Cheng, Mu-Hua; Chen, Yi

    2013-01-01

    The objective of this study was to determine whether the gamma rays emitted from the radionuclide effect bone mineral density (BMD) measurement. Nine subjects (mean age: 56 ± 17.96 yr) scheduled for bone scanning underwent BMD measurement using dual-energy X-ray absorptiometry (DXA) (Hologic/Discovery A) before and 1, 2, and 4 h after injection of technetium-99m-methylene diphosphonate (99mTc-MDP). Ten subjects (mean age: 41 ± 15.47 yr) scheduled for therapy of differentiated thyroid carcinoma with iodine-131 underwent BMD measurement before and 2 h after therapeutic radionuclide administration. All patients were given whole body BMD measurement, including head, arm, ribs, lumbar spine, pelvis, and leg sites. Besides, patients who referred to radioiodine therapy were given total hip and femoral neck BMD measurement as well. No statistically significant changes in BMD values were detected after 99mTc-MDP and iodine-131 administration for all measurement sites (p > 0.05), and individual difference of BMD before and after radionuclide imaging or therapy was less than the least significant change in lumbar spine, total hip, and femoral neck. In conclusion, BMD measurements are not influenced by the gamma rays emitted from technetium-99m and iodine-131. DXA bone densitometry may be performed simultaneously with bone scanning and radioiodine therapy. Copyright © 2013 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.

  12. Removing respiratory artefacts from transthoracic bioimpedance spectroscopy measurements

    NASA Astrophysics Data System (ADS)

    Cuba-Gyllensten, I.; Abtahi, F.; Bonomi, A. G.; Lindecrantz, K.; Seoane, F.; Amft, O.

    2013-04-01

    Transthoracic impedance spectroscopy (TIS) measurements from wearable textile electrodes provide a tool to remotely and non-invasively monitor patient health. However, breathing and cardiac processes inevitably affect TIS measurements, since they are sensitive to changes in geometry and air or fluid volumes in the thorax. This study aimed at investigating the effect of respiration on Cole parameters extracted from TIS measurements and developing a method to suppress artifacts. TIS data were collected from 10 participants at 16 frequencies (range: 10 kHz - 1 MHz) using a textile electrode system (Philips Technologie Gmbh). Simultaneously, breathing volumes and frequency were logged using an electronic spirometer augmented with data from a breathing belt. The effect of respiration on TIS measurements was studied at paced (10 and 16 bpm) deep and shallow breathing. These measurements were repeated for each subject in three different postures (lying down, reclining and sitting). Cole parameter estimation was improved by assessing the tidal expiration point thus removing breathing artifacts. This leads to lower intra-subject variability between sessions and a need for less measurements points to accurately assess the spectra. Future work should explore algorithmic artifacts compensation models using breathing and posture or patient contextual information to improve ambulatory transthoracic impedance measurements.

  13. Real-time specific surface area measurements via laser-induced breakdown spectroscopy

    USGS Publications Warehouse

    Washburn, Kathryn E.; Birdwell, Justin E.; Howard, James E.

    2017-01-01

    From healthcare to cosmetics to environmental science, the specific surface area (SSA) of micro- and mesoporous materials or products can greatly affect their chemical and physical properties. SSA results are also widely used to examine source rocks in conventional and unconventional petroleum resource plays. Despite its importance, current methods to measure SSA are often cumbersome, time-consuming, or require cryogenic consumables (e.g., liquid nitrogen). These methods are not amenable to high-throughput environments, have stringent sample preparation requirements, and are not practical for use in the field. We present a new application of laser-induced breakdown spectroscopy for rapid measurement of SSA. This study evaluates geological samples, specifically organic-rich oil shales, but the approach is expected to be applicable to many other types of materials. The method uses optical emission spectroscopy to examine laser-generated plasma and quantify the amount of argon adsorbed to a sample during an inert gas purge. The technique can accommodate a wide range of sample sizes and geometries and has the potential for field use. These advantages for SSA measurement combined with the simultaneous acquisition of composition information make this a promising new approach for characterizing geologic samples and other materials.

  14. Free radicals properties of gamma-irradiated penicillin-derived antibiotics: piperacillin, ampicillin, and crystalline penicillin.

    PubMed

    Wilczyński, Sławomir; Pilawa, Barbara; Koprowski, Robert; Wróbel, Zygmunt; Ptaszkiewicz, Marta; Swakoń, Jan; Olko, Paweł

    2014-03-01

    The aim of this work was to determine the concentrations and properties of free radicals in piperacillin, ampicillin, and crystalline penicillin after gamma irradiation. The radicals were studied by electron paramagnetic resonance (EPR) spectroscopy using an X-band spectrometer (9.3 GHz). Gamma irradiation was performed at a dose of 25 kGy. One- and two-exponential functions were fitted to the experimental data, in order to assess the influence of the antibiotics' storage time on the measured EPR lines. After gamma irradiation, complex EPR lines were recorded confirming the presence of a large number of free radicals formed during the irradiation. For all tested antibiotics, concentrations of free radicals and parameters of EPR spectra changed with storage time. The results obtained demonstrate that concentration of free radicals and other spectroscopic parameters can be used to select the optimal parameters of radiation sterilization of β-lactam antibiotics. The most important parameters are the constants τ (τ (1(A),(I)) and τ (2(A),(I))) and K (K (0(A),(I)), K (1(A),(I)), K (2(A),(I))) of the exponential functions that describe free radicals decay during samples storage.

  15. Spatially-resolved HPGe Gamma-ray Spectroscopy of Swipe Samples

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McDonald, Benjamin S.; VanDevender, Brent A.; Wood, Lynn S.

    Measurement of swipe samples is a critical element of the National Technical Nuclear Forensics (NTNF) mission. A unique, portable, germanium gamma imager (GeGI-s) from PHDS Co may provide complementary information to current techniques for swipe sample screening. The GeGI-s is a modified version of the commercial GeGI-4, a planar HPGe detector, capable of several million counts per second across the whole detector. The GeGI-s detector is a prototype of a commercial off-the-shelf high rate GeGI. The high rate capability allows high-activity samples be placed directly on the face of the detector. Utilizing the high energy resolution and pixelization of themore » detector, the GeGI-s can generate isotope specific spatial maps of the materials on the swipe sample. To prove this technology is viable for such mapping, the GeGI-s detector response to spatially distributed events must be well characterized. The detection efficiency as a function of location has been characterized to understand the non-uniformities presented as a collimated photon beam was rastered vertically and horizontally across the face of the detector. The detection efficiency as a function of location has been characterized to understand the non-uniformities presented as a collimated photon beam was rastered vertically and horizontally across the face of the detector. The response was found to be primarily uniform and symmetric, however two causes of non-uniformity were found. Both of these causes can ultimately be corrected for in off-line data analysis.« less

  16. FEASIBILITY STUDY TO DEMONSTRATE APPLICABILITY OF TUNABLE INFRARED LASER EMISSION SPECTROSCOPY TECHNOLOGY TO MEASURE AIR POLLUTION

    EPA Science Inventory

    This project involves the real-time measurement of air quality using open-path IR spectroscopy. A prototype open-path tunable laser absorption spectroscopy instrument was designed, built, and successfully operated for several hundred hours between October and December 2000. The...

  17. Measurement of magnetic field gradients using Raman spectroscopy in a fountain

    NASA Astrophysics Data System (ADS)

    Srinivasan, Arvind; Zimmermann, Matthias; Efremov, Maxim A.; Davis, Jon P.; Narducci, Frank A.

    2017-02-01

    In many experiments involving cold atoms, it is crucial to know the strength of the magnetic field and/or the magnetic field gradient at the precise location of a measurement. While auxiliary sensors can provide some of this information, the sensors are usually not perfectly co-located with the atoms and so can only provide an approximation to the magnetic field strength. In this article, we describe a technique to measure the magnetic field, based on Raman spectroscopy, using the same atomic fountain source that will be used in future magnetically sensitive measurements.

  18. Measuring atmospheric visibility cavity attenuated phase shift spectroscopy

    NASA Astrophysics Data System (ADS)

    Jie, Guo; Ye, Shan-Shan; Yang, Xiao; Han, Ye-Xing; Tang, Huai-Wu; Yu, Zhi-Wei

    2016-10-01

    In the paper, an accurate and sensitive cavity attenuated phase shift spectroscopy (CAPS) system was used to monitor the atmospheric visibility coefficient in urban areas. The CAPS system, which detects the atmospheric visibility within a 10 nm bandpass centered at 532 nm, comprises a green LED with center wavelength in 532nm, a resonant optical cavity (36 cm length), a Photo Multiplier Tube detector and a lock in amplifier. The performance of the CAPS system was evaluated by measuring of the stability and response of the system. The minima ( 0.06 Mm-1) in the Allan plots show the optimum average time( 80s) for optimum detection performance of the CAPS system. The 2L/min flow rate, the CAPS system rise and fall response time is about 15 s, so as to realize the fast measurement of visibility. By comparing the forward scatter visibility meter measurement results, the CAPS system measurement results are verified reliably, and have high precision measurement. These figures indicate that this method has the potential to become one of the most sensitive on-line analytical techniques for atmospheric visibility detection.

  19. Feasibility of Bioelectrical Impedance Spectroscopy Measurement before and after Thoracentesis

    PubMed Central

    Weyer, Sören; Pauly, Karolin; Napp, Andreas; Dreher, Michael; Leonhardt, Steffen; Marx, Nikolaus; Schauerte, Patrick; Mischke, Karl

    2015-01-01

    Background. Bioelectrical impedance spectroscopy is applied to measure changes in tissue composition. The aim of this study was to evaluate its feasibility in measuring the fluid shift after thoracentesis in patients with pleural effusion. Methods. 45 participants (21 with pleural effusion and 24 healthy subjects) were included. Bioelectrical impedance was analyzed for “Transthoracic,” “Foot to Foot,” “Foot to Hand,” and “Hand to Hand” vectors in low and high frequency domain before and after thoracentesis. Healthy subjects were measured at a single time point. Results. The mean volume of removed pleural effusion was 1169 ± 513 mL. The “Foot to Foot,” “Hand to Hand,” and “Foot to Hand” vector indicated a trend for increased bioelectrical impedance after thoracentesis. Values for the low frequency domain in the “Transthoracic” vector increased significantly (P < 0.001). A moderate correlation was observed between the amount of removed fluid and impedance change in the low frequency domain using the “Foot to Hand” vector (r = −0.7). Conclusion. Bioelectrical impedance changes in correlation with the thoracic fluid level. It was feasible to monitor significant fluid shifts and loss after thoracentesis in the “Transthoracic” vector by means of bioelectrical impedance spectroscopy. The trial is registered with Registration Numbers IRB EK206/11 and NCT01778270. PMID:25861647

  20. Direct measurement of 235U in spent fuel rods with Gamma-ray mirrors

    NASA Astrophysics Data System (ADS)

    Ruz, J.; Brejnholt, N. F.; Alameda, J. B.; Decker, T. A.; Descalle, M. A.; Fernandez-Perea, M.; Hill, R. M.; Kisner, R. A.; Melin, A. M.; Patton, B. W.; Soufli, R.; Ziock, K.; Pivovaroff, M. J.

    2015-03-01

    Direct measurement of plutonium and uranium X-rays and gamma-rays is a highly desirable non-destructive analysis method for the use in reprocessing fuel environments. The high background and intense radiation from spent fuel make direct measurements difficult to implement since the relatively low activity of uranium and plutonium is masked by the high activity from fission products. To overcome this problem, we make use of a grazing incidence optic to selectively reflect Kα and Kβ fluorescence of Special Nuclear Materials (SNM) into a high-purity position-sensitive germanium detector and obtain their relative ratios.

  1. Improvement of sensitivity in PIGE analysis of steels by neutron-gamma coincidences measurement

    NASA Astrophysics Data System (ADS)

    Ene, Antoaneta

    2004-07-01

    In this work the sensitivities of minor elements in a standard steel sample EURONORM-CRM No. 085-1 irradiated with beams of 5.5 MeV protons and 5 MeV deuterons have been determined both by regular proton- (p-PIGE) and deuteron-induced prompt gamma-ray emission (d-PIGE) methods and with the selection of the (p, n) and (d, n) reaction channels, measuring the neutron-gamma coincidences. A check on the elemental composition of the steel standard has also been carried out using combined INAA and PIXE and quantitative determinations have been done for some elements whose concentrations were not specified by the manufacturer, such as Al, As, Cr, Mo, Na, Ni, W. This complex study has resulted in a significant improvement of the sensitivities for some minor elements in steel by reducing the background and increasing the peak-to-background ratio in the coincident prompt gamma-rays spectra as a result of the elimination of the competing nuclear reactions originating from isotopes of the adjacent elements in the periodic table, present in the steel target. This extension of the PIGE method could be adapted by any analyst with the necessary equipment for the analysis of a wide variety of matrices that are refractory enough to withstand the heating effect of the bombarding beam, taking into account that this type of experiment requires longer irradiation times.

  2. Measurement of the 238U neutron-capture cross section and gamma-emission spectra from 10 eV to 100 keV using the DANCE detector at LANSCE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ullmann, John L; Couture, A J; Keksis, A L

    2010-01-01

    A careful new measurement of the {sup 238}U(n,{gamma}) cross section from 10 eV to 100 keV has been made using the DANCE detector at LANSCE. DANCE is a 4{pi} calorimetric scintillator array consisting of 160 BaF{sub 2} crystals. Measurements were made on a 48 mg/cm{sup 2} depleted uranium target. The cross sections are in general good agreement with previous measurements. The gamma-ray emission spectra, as a function of gamma multiplicity, were also measured and compared to model calculations.

  3. Thermodynamic confinement and alpha-helix persistence length in poly(gamma-benzyl-L-glutamate)-b-poly(dimethyl siloxane)-b-poly(gamma-benzyl-L-glutamate) triblock copolymers.

    PubMed

    Papadopoulos, P; Floudas, G; Schnell, I; Lieberwirth, I; Nguyen, T Q; Klok, H-A

    2006-02-01

    The structure and the associated dynamics of a series of poly(gamma-benzyl-L-glutamate)-b-poly(dimethyl siloxane)-b-poly(gamma-benzyl-L-glutamate) (PBLG-b-PDMS-b-PBLG) triblock copolymers were investigated using small- and wide-angle X-ray scattering, NMR, transmission electron microscopy, and dielectric spectroscopy, respectively. The structural analysis revealed phase separation in the case of the longer blocks with defected alpha-helical segments embedded within the block copolymer nanodomains. The alpha-helical persistence length was found to depend on the degree of segregation; thermodynamic confinement and chain stretching results in the partial annihilation of helical defects.

  4. Measurement of the High-Energy Gamma-Ray Emission from the Moon with the Fermi Large Area Telescope

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; hide

    2016-01-01

    We have measured the gamma-ray emission spectrum of the Moon using the data collected by the Large Area Telescope onboard the Fermi satellite during its first seven years of operation, in the energy range from 30 MeV up to a few GeV. We have also studied the time evolution of the flux, finding a correlation with the solar activity. We have developed a full Monte Carlo simulation describing the interactions of cosmic rays with the lunar surface. The results of the present analysis can be explained in the framework of this model, where the production of gamma rays is due to the interactions of cosmic-ray proton and helium nuclei with the surface of the Moon. Finally, we have used our simulation to derive the cosmic-ray proton and helium spectra near Earth from the Moon gamma-ray data.

  5. Neutron flux and gamma dose measurement in the BNCT irradiation facility at the TRIGA reactor of the University of Pavia

    NASA Astrophysics Data System (ADS)

    Bortolussi, S.; Protti, N.; Ferrari, M.; Postuma, I.; Fatemi, S.; Prata, M.; Ballarini, F.; Carante, M. P.; Farias, R.; González, S. J.; Marrale, M.; Gallo, S.; Bartolotta, A.; Iacoviello, G.; Nigg, D.; Altieri, S.

    2018-01-01

    University of Pavia is equipped with a TRIGA Mark II research nuclear reactor, operating at a maximum steady state power of 250 kW. It has been used for many years to support Boron Neutron Capture Therapy (BNCT) research. An irradiation facility was constructed inside the thermal column of the reactor to produce a sufficient thermal neutron flux with low epithermal and fast neutron components, and low gamma dose. In this irradiation position, the liver of two patients affected by hepatic metastases from colon carcinoma were irradiated after borated drug administration. The facility is currently used for cell cultures and small animal irradiation. Measurements campaigns have been carried out, aimed at characterizing the neutron spectrum and the gamma dose component. The neutron spectrum has been measured by means of multifoil neutron activation spectrometry and a least squares unfolding algorithm; gamma dose was measured using alanine dosimeters. Results show that in a reference position the thermal neutron flux is (1.20 ± 0.03) ×1010 cm-2 s-1 when the reactor is working at the maximum power of 250 kW, with the epithermal and fast components, respectively, 2 and 3 orders of magnitude lower than the thermal component. The ratio of the gamma dose with respect to the thermal neutron fluence is 1.2 ×10-13 Gy/(n/cm2).

  6. Measurement of radon/thoron exhalation rates and gamma-ray dose rate in granite areas in Japan.

    PubMed

    Prasad, G; Ishikawa, T; Hosoda, M; Sahoo, S K; Kavasi, N; Sorimachi, A; Tokonami, S; Uchida, S

    2012-11-01

    Radon and thoron exhalation rates and gamma-ray dose rate in different places in Hiroshima Prefecture were measured. Exhalation rates were measured using an accumulation chamber method. The radon exhalation rate was found to vary from 3 to 37 mBq m(-2) s(-1), while the thoron exhalation rate ranged from 40 to 3330 mBq m(-2) s(-1). The highest radon exhalation rate (37 mBq m(-2) s(-1)) and gamma-ray dose rate (92 nGy h(-1)) were found in the same city (Kure City). In Kure City, indoor radon and thoron concentrations were previously measured at nine selected houses using a radon-thoron discriminative detector (Raduet). The indoor radon concentrations varied from 16 to 78 Bq m(-3), which was higher than the average value in Japan (15.5 Bq m(-3)). The indoor thoron concentration ranged from ND (not detected: below a detection limit of approximately 10 Bq m(-3)) to 314 Bq m(-3). The results suggest that radon exhalation rate from the ground is an influential factor for indoor radon concentration.

  7. Status of the GAMMA-400 Project

    NASA Technical Reports Server (NTRS)

    Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Gusakov, Yu. V.; Farber, M. O.; hide

    2013-01-01

    The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100 MeV-3 TeV is presented. The angular resolution of the instrument, 1-2 deg at E(gamma) approximately 100 MeV and approximately 0.01 at E(gamma) greater than 100 GeV, its energy resolution is approximately 1% at E(gamma) greater than 100 GeV, and the proton rejection factor is approximately 10(exp 6) are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.

  8. Simultaneous measurement of (n,{gamma}) and (n,fission) cross sections with the DANCE 4{pi} BaF2 array

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bredeweg, T. A.; Fowler, M. M.; Bond, E. M.

    2006-03-13

    Neutron capture cross section measurements on many of the actinides are complicated by low-energy neutron-induced fission, which competes with neutron capture to varying degrees depending on the nuclide of interest. Measurements of neutron capture on 235U using the Detector for Advanced Neutron Capture Experiments (DANCE) have shown that we can partially resolve capture from fission events based on total photon calorimetry (i.e. total {gamma}-ray energy and {gamma}-ray multiplicity per event). The addition of a fission-tagging detector to the DANCE array will greatly improve our ability to separate these two competing processes so that improved neutron capture and (n,{gamma})/(n,fission) cross sectionmore » ratio measurements can be obtained. The addition of a fission-tagging detector to the DANCE array will also provide a means to study several important issues associated with neutron-induced fission, including (n,fission) cross sections as a function of incident neutron energy, and total energy and multiplicity of prompt fission photons. We have focused on two detector designs with complementary capabilities, a parallel-plate avalanche counter and an array of solar cells.« less

  9. Measurement of the 21Na(p,{gamma})22Mg Reaction with the Dragon Facility at TRIUMF-ISAC

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, A.A.; Bishop, S.; D'Auria, J.M.

    2003-08-26

    The DRAGON recoil separator facility, designed to measure the rates of radiative proton and alpha capture reactions important for nuclear astrophysics, is now operational at the TRIUMF-ISAC radioactive beam facility in Vancouver, Canada. We report on first measurements of the 21Na(p,{gamma})22Mg reaction rate with radioactive beams of 21Na.

  10. A high-resolution gamma-ray and hard X-ray spectrometer for solar flare observations in Max 1991

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Curtis, D. W.; Harvey, P.; Hurley, K.; Primbsch, J. H.; Smith, D. M.; Pelling, R. M.; Duttweiler, F.

    1988-01-01

    A long duration balloon flight instrument for Max 1991 designed to study the acceleration of greater than 10 MeV ions and greater than 15 keV electrons in solar flares through high resolution spectroscopy of the gamma ray lines and hard X-ray and gamma ray continuum is described. The instrument, HIREGS, consists of an array of high-purity, n-type coaxial germanium detectors (HPGe) cooled to less than 90 K and surrounded by a bismuth germanate (BGO) anticoincidence shield. It will cover the energy range 15 keV to 20 MeV with keV spectral resolution, sufficient for accurate measurement of all parameters of the expected gamma ray lines with the exception of the neutron capture deuterium line. Electrical segmentation of the HPGe detector into a thin front segment and a thick rear segment, together with pulse-shape discrimination, provides optimal dynamic range and signal-to-background characteristics for flare measurements. Neutrons and gamma rays up to approximately 0.1 to 1 GeV can be detected and identified with the combination of the HPGe detectors and rear BGO shield. The HIREGS is planned for long duration balloon flights (LDBF) for solar flare studies during Max 1991. The two exploratory LDBFs carried out at mid-latitudes in 1987 to 1988 are described, and the LDBFs in Antarctica, which could in principle provide 24 hour/day solar coverage and very long flight durations (20 to 30 days) because of minimal ballast requirements are discussed.

  11. Polarization-direction correlation measurement --- Experimental test of the PDCO methods

    NASA Astrophysics Data System (ADS)

    Starosta, K.; Morek, T.; Droste, Ch.; Rohoziński, S. G.; Srebrny, J.; Bergstrem, M.; Herskind, B.

    1998-04-01

    Information about spins and parities of excited states is crucial for nuclear structure studies. In ``in-beam" gamma ray spectroscopy the directional correlation (DCO) or angular distribution measurements are widely used tools for multipolarity assignment; although, it is known that neither of these methods is sensitive to electric or magnetic character of gamma radiation. Multipolarity of gamma rays may be determined when the results of the DCO analysis are combined with the results of linear polarization measurements. The large total efficiency of modern multidetector arrays allows one to carry out coincidence measurements between the polarimeter and the remaining detectors. The aim of the present study was to test experimentally the possibility of polarization-direction correlation measurements using the EUROGAM II array. The studied nucleus was ^164Yb produced in the ^138Ba(^30Si,4n) reaction at beam energies of 150 and 155 MeV. The angular correlation, linear polarization and direction-polarization correlation were measured for the strong transitions in yrast and non yrast cascades. Application of the PDCO analysis to a transition connecting a side band with the yrast band allowed one to rule out most of the ambiguities in multipolarity assignment occuring if one used angular correlations only.

  12. Gamma irradiation assisted fungal degradation of the polypropylene/biomass composites

    NASA Astrophysics Data System (ADS)

    Butnaru, Elena; Darie-Niţă, Raluca Nicoleta; Zaharescu, Traian; Balaeş, Tiberius; Tănase, Cătălin; Hitruc, Gabriela; Doroftei, Florica; Vasile, Cornelia

    2016-08-01

    White-rot fungus Bjerkandera adusta has been tested for its ability to degrade some biocomposites materials based on polypropylene and biomass (Eucalyptus globulus, pine cones, and Brassica rapa). γ-irradiation was applied to initiate the degradation of relatively inert polypropylene matrix. The degradation process has been studied by scanning electron microscopy, atomic force microscopy, infrared spectroscopy, contact angle measurements, rheological and chemiluminescence tests. These analyses showed that the polypropylene/biomass composites properties are worsen under the action of the selected microorganism. The formation of cracks and scrap particles over the entire matrix surface and the decrease of the complex viscosity values, as well as the dynamic moduli of gamma irradiated PP/biomass composite and exposed to Bjerkandera adusta fungus, indicate fungal efficiency in composite degradation.

  13. The solar gamma ray and neutron capabilities of COMPTEL on the Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Ryan, James M.; Lockwood, John A.

    1989-01-01

    The imaging Compton telescope COMPTEL on the Gamma Ray Observatory (GRO) has unusual spectroscopic capabilities for measuring solar gamma-ray and neutron emission. The launch of the GRO is scheduled for June 1990 near the peak of the sunspot cycle. With a 30 to 40 percent probability for the Sun being in the COMPTEL field-of-view during the sunlit part of an orbit, a large number of flares will be observed above the 800 keV gamma-ray threshold of the telescope. The telescope energy range extends to 30 MeV with high time resolution burst spectra available from 0.1 to 10 MeV. Strong Compton tail suppression of instrumental gamma-ray interactions will facilitate improved spectral analysis of solar flare emissions. In addition, the high signal to noise ratio for neutron detection and measurement will provide new neutron spectroscopic capabilities. Specifically, a flare similar to that of 3 June 1982 will provide spectroscopic data on greater than 1500 individual neutrons, enough to construct an unambiguous spectrum in the energy range of 20 to 200 MeV. Details of the instrument and its response to solar gamma-rays and neutrons will be presented.

  14. Evidence for Direct CP Violation in the Measurement of the Cabibbo-Kobayashi-Maskawa Angle gamma with B-+ to D(*) K(*)-+ Decays

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    del Amo Sanchez, P.; Lees, J.P.; Poireau, V.

    2011-08-19

    We report the measurement of the Cabibbo-Kobayashi-Maskawa CP-violating angle {gamma} through a Dalitz plot analysis of neutral D meson decays to K{sub S}{sup 0}{pi}{sup +}{pi}{sup -} and K{sub S}{sup 0} K{sup +}K{sup -} produced in the processes B{sup {-+}} {yields} DK{sup {-+}}, B{sup {-+}} {yields} D* K{sup {-+}} with D* {yields} D{pi}{sup 0}, D{gamma}, and B{sup {-+}} {yields} DK*{sup {-+}} with K*{sup {-+}} {yields} K{sub S}{sup 0}{pi}{sup {-+}}, using 468 million B{bar B} pairs collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC. We measure {gamma} = (68 {+-} 14 {+-} 4 {+-} 3){supmore » o} (modulo 180{sup o}), where the first error is statistical, the second is the experimental systematic uncertainty and the third reflects the uncertainty in the description of the neutral D decay amplitudes. This result is inconsistent with {gamma} = 0 (no direct CP violation) with a significance of 3.5 standard deviations.« less

  15. Low-background gamma spectroscopy at the Boulby Underground Laboratory

    NASA Astrophysics Data System (ADS)

    Scovell, P. R.; Meehan, E.; Araújo, H. M.; Dobson, J.; Ghag, C.; Kraus, H.; Kudryavtsev, V. A.; Liu, X.-. R.; Majewski, P.; Paling, S. M.; Preece, R. M.; Saakyan, R.; Tomás, A.; Toth, C.; Yeoman, L. M.

    2018-01-01

    The Boulby Underground Germanium Suite (BUGS) comprises three low-background, high-purity germanium detectors operating in the Boulby Underground Laboratory, located 1.1 km underground in the north-east of England, UK. BUGS utilises three types of detector to facilitate a high-sensitivity, high-throughput radio-assay programme to support the development of rare-event search experiments. A Broad Energy Germanium (BEGe) detector delivers sensitivity to low-energy gamma-rays such as those emitted by 210Pb and 234Th. A Small Anode Germanium (SAGe) well-type detector is employed for efficient screening of small samples. Finally, a standard p-type coaxial detector provides fast screening of standard samples. This paper presents the steps used to characterise the performance of these detectors for a variety of sample geometries, including the corrections applied to account for cascade summing effects. For low-density materials, BUGS is able to radio-assay to specific activities down to 3.6mBqkg-1 for 234Th and 6.6mBqkg-1 for 210Pb both of which have uncovered some significant equilibrium breaks in the 238U chain. In denser materials, where gamma-ray self-absorption increases, sensitivity is demonstrated to specific activities of 0.9mBqkg-1 for 226Ra, 1.1mBqkg-1 for 228Ra, 0.3mBqkg-1 for 224Ra, and 8.6mBqkg-1 for 40K with all upper limits at a 90% confidence level. These meet the requirements of most screening campaigns presently under way for rare-event search experiments, such as the LUX-ZEPLIN (LZ) dark matter experiment. We also highlight the ability of the BEGe detector to probe the X-ray fluorescence region which can be important to identify the presence of radioisotopes associated with neutron production; this is of particular relevance in experiments sensitive to nuclear recoils.

  16. Measuring cloud thermodynamic phase with shortwave infrared imaging spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Thompson, David R.; McCubbin, Ian; Gao, Bo Cai

    Shortwave Infrared imaging spectroscopy enables accurate remote mapping of cloud thermodynamic phase at high spatial resolution. We describe a measurement strategy to exploit signatures of liquid and ice absorption in cloud top apparent reflectance spectra from 1.4 to 1.8 μm. This signal is generally insensitive to confounding factors such as solar angles, view angles, and surface albedo. We first evaluate the approach in simulation and then apply it to airborne data acquired in the Calwater-2/ACAPEX campaign of Winter 2015. Here NASA’s “Classic” Airborne Visible Infrared Imaging Spectrometer (AVIRIS-C) remotely observed diverse cloud formations while the U.S. Department of Energy ARMmore » Aerial Facility G-1 aircraft measured cloud integral and microphysical properties in situ. Finally, the coincident measurements demonstrate good separation of the thermodynamic phases for relatively homogeneous clouds.« less

  17. Technical Note: Relationships between gamma criteria and action levels: Results of a multicenter audit of gamma agreement index results.

    PubMed

    Crowe, Scott B; Sutherland, Bess; Wilks, Rachael; Seshadri, Venkatakrishnan; Sylvander, Steven; Trapp, Jamie V; Kairn, Tanya

    2016-03-01

    The aim of this work was to use a multicenter audit of modulated radiotherapy quality assurance (QA) data to provide a practical examination of gamma evaluation criteria and action level selection. The use of the gamma evaluation method for patient-specific pretreatment QA is widespread, with most commercial solutions implementing the method. Gamma agreement indices were calculated using the criteria 1%/1 mm, 2%/2 mm, 2%/3 mm, 3%/2 mm, 3%/3 mm, and 5%/3 mm for 1265 pretreatment QA measurements, planned at seven treatment centers, using four different treatment planning systems, delivered using three different delivery systems (intensity-modulated radiation therapy, volumetric-modulated arc therapy, and helical tomotherapy) and measured using three different dose measurement systems. The sensitivity of each pair of gamma criteria was evaluated relative to the gamma agreement indices calculated using 3%/3 mm. A linear relationship was observed for 2%/2 mm, 2%/3 mm, and 3%/2 mm. This result implies that most beams failing at 3%/3 mm would also fail for those criteria, if the action level was adjusted appropriately. Some borderline plans might be passed or failed depending on the relative priority (tighter tolerance) used for dose difference or distance to agreement evaluation. Dosimeter resolution and treatment modality were found to have a smaller effect on the results of QA measurements than the number of dimensions (2D or 3D) over which the gamma evaluation was calculated. This work provides a method (and a large sample of results) for calculating equivalent action levels for different gamma evaluation criteria. This work constitutes a valuable guide for clinical decision making and a means to compare published gamma evaluation results from studies using different evaluation criteria. More generally, the data provided by this work support the recommendation that gamma criteria that specifically prioritize the property of greatest clinical importance for each

  18. Measurement of total-body cobalt-57 vitamin B12 absorption with a gamma camera.

    PubMed

    Cardarelli, J A; Slingerland, D W; Burrows, B A; Miller, A

    1985-08-01

    Previously described techniques for the measurement of the absorption of [57Co]vitamin B12 by total-body counting have required an iron room equipped with scanning or multiple detectors. The present study uses simplifying modifications which make the technique more available and include the use of static geometry, the measurement of body thickness to correct for attenuation, a simple formula to convert the capsule-in-air count to a 100% absorption count, and finally the use of an adequately shielded gamma camera obviating the need of an iron room.

  19. Electrode placement in bioimpedance spectroscopy: evaluation of alternative positioning of electrodes when measuring relative dehydration in athletes.

    PubMed

    Birkemose, M; Møller, A J; Madsen, M L; Brantlov, S; Sørensen, H; Overgaard, K; Johansen, P

    2013-01-01

    In order to maintain a homeostatic environment in human cells, the balance between absorption and separation of water must be retained. Imbalance will have consequences on both the cellular and organ levels. Studies performed on athletes have shown coherence between their hydration status and ability to perform. A dehydration of 2-7% of total body weight resulted in a marked decrease in performance. Measurement and monitoring of hydration status may be used to optimize athlete performance. Therefore, in this current study bioimpedance spectroscopy is used to determine the hydration status of athletes. Trials were made to investigate alternative ways of electrode placement when performing bioimpedance spectroscopy in order to measure relative dehydration. A total of 14 test subjects underwent measurements before, during, and after a cycle test of 3×25min. Electrodes where placed to measure body impedance in three different ways: wrist-ankle (recommended method), wrist-wrist, and transthoracic. Furthermore, the relative loss in weight of the subjects during the trial was registered. The study showed no relation between relative weight loss and the wrist-wrist and transthoracic placement method, using bioimpedance spectroscopy to measure relative dehydration. The inability of the method to detect such relative changes in hydration may be due to the bioimpedance spectroscopy technology being extremely sensitive to changes in skin temperature, movement artifacts, thoroughness in placing the electrodes, and the physiological impact on the human body when performing exercise. Therefore, further research into the area of bioimpedance spectroscopy is needed before this methodology can be applied in monitoring active athletes. Hence, a simple weight measurement still seems a more useful way of determining a relative change of hydration in an active setting.

  20. Light trapping in thin-film solar cells measured by Raman spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ledinský, M., E-mail: ledinsky@fzu.cz; Photovoltaics and Thin Film Electronics Laboratory, Institute of Microengineering; Moulin, E.

    2014-09-15

    In this study, Raman spectroscopy is used as a tool to determine the light-trapping capability of textured ZnO front electrodes implemented in microcrystalline silicon (μc-Si:H) solar cells. Microcrystalline silicon films deposited on superstrates of various roughnesses are characterized by Raman micro-spectroscopy at excitation wavelengths of 442 nm, 514 nm, 633 nm, and 785 nm, respectively. The way to measure quantitatively and with a high level of reproducibility the Raman intensity is described in details. By varying the superstrate texture and with it the light trapping in the μc-Si:H absorber layer, we find significant differences in the absolute Raman intensity measured in the near infraredmore » wavelength region (where light trapping is relevant). A good agreement between the absolute Raman intensity and the external quantum efficiency of the μc-Si:H solar cells is obtained, demonstrating the validity of the introduced method. Applications to thin-film solar cells, in general, and other optoelectronic devices are discussed.« less

  1. Sky and Elemental Planetary Mapping Via Gamma Ray Emissions

    NASA Technical Reports Server (NTRS)

    Roland, John M.

    2011-01-01

    Low-energy gamma ray emissions ((is) approximately 30keV to (is) approximately 30MeV) are significant to astrophysics because many interesting objects emit their primary energy in this regime. As such, there has been increasing demand for a complete map of the gamma ray sky, but many experiments to do so have encountered obstacles. Using an innovative method of applying the Radon Transform to data from BATSE (the Burst And Transient Source Experiment) on NASA's CGRO (Compton Gamma-Ray Observatory) mission, we have circumvented many of these issues and successfully localized many known sources to 0.5 - 1 deg accuracy. Our method, which is based on a simple 2-dimensional planar back-projection approximation of the inverse Radon transform (familiar from medical CAT-scan technology), can thus be used to image the entire sky and locate new gamma ray sources, specifically in energy bands between 200keV and 2MeV which have not been well surveyed to date. Samples of these results will be presented. This same technique can also be applied to elemental planetary surface mapping via gamma ray spectroscopy. Due to our method's simplicity and power, it could potentially improve a current map's resolution by a significant factor.

  2. Measurement of the high-energy gamma-ray emission from the Moon with the Fermi Large Area Telescope

    DOE PAGES

    Ackermann, M.; Ajello, M.; Albert, A.; ...

    2016-04-08

    We have measured the gamma-ray emission spectrum of the Moon using the data collected by the Large Area Telescope onboard the Fermi satellite during its first seven years of operation, in the energy range from 30 MeV up to a few GeV. We have also studied the time evolution of the flux, finding a correlation with the solar activity. We have developed a full Monte Carlo simulation describing the interactions of cosmic rays with the lunar surface. The results of the present analysis can be explained in the framework of this model, where the production of gamma rays is duemore » to the interactions of cosmic-ray proton and helium nuclei with the surface of the Moon. Lastly, we have used our simulation to derive the cosmic-ray proton and helium spectra near Earth from the Moon gamma-ray data.« less

  3. A burst of energetic gamma rays. [measured by balloon-borne instruments

    NASA Technical Reports Server (NTRS)

    Koga, R.; Simnett, G.; White, R. S.

    1974-01-01

    A burst of gamma rays with energies greater than 1 MeV occurring on May 14, 1972, at 201247 UT (151247 local time) was detected during a balloon flight from Palestine, Texas, at a float altitude of 4g/sq cm residual atmosphere. The detector was a tank of liquid scintillator 1m x 0.5 m x 15 cm surrounded by a 0.6 cm plastic scintillator in anticoincidence. The signal was 60 standard deviations above a steady background of 600 counts/sec. The flux was 0.12 (+0.07 or -0.04) gamma/sq cm, and the time integrated flux 20(+11 or -7) gamma/sq cm. Only one such event was seen during the 8 hours of observation in the daytime on May 14 and 15. Two sub-flares in H alpha occurred during the burst, but not coincident with the start time. A detector on the Solrad satellite observed X-rays on all channels 2 minutes after the gamma ray start time. This event is similar to three earlier reported events.

  4. Novel synthesis of cobalt/poly vinyl alcohol/gamma alumina nanocomposite for catalytic application

    NASA Astrophysics Data System (ADS)

    Hatamie, Shadie; Ahadian, Mohammad Mahdi; Rashidi, Alimoradeh; Karimi, Ali; Akhavan, Omid

    2017-05-01

    In this manuscript, synthesis of cobalt/poly vinyl alcohol (PVA)/gamma alumina nanocomposite via a simple room temperature, as well as its catalyst performance were explored. Brunauer-Emmett-Teller analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy were conducted. The surface area of the polymeric composite was obtained to be 280 m2/g. The cobalt loading on the nanocomposite was measured using inductivity couple plasma. Transmission electron microscopy analysis showed that the size of cobalt crystalline encapsulate inside the polymer was confined to 5 nm. Magnetic property analysis, using vibrating sample magnetometer, confirmed ferromagnetic nature of the composite. Thermo-gravimetric analyses were employed to explain the degradation process for the polymeric base nanocomposite. Temperature-programmed reduction was used to evaluate the structural form of cobalt oxide in nanocomposite. The catalysis activity was determined by Fischer-Tropsch synthesize, which showed a high catalyst selectivity to C2-C4 hydrocarbons.

  5. Mössbauer study of the effect of gamma irradiation on the removal of pyrite from Colombian coals

    NASA Astrophysics Data System (ADS)

    Mejía, J. A.; Reyes Caballero, F.; Palacio, C. A.; de Grave, E.; Olaya Dávila, H.; Martínez Ovalle, S. A.

    2014-04-01

    The removal of sulfur from the coals is necessary before using it. It is due to the environmental and technological problems that it causes. In this work, the results of the study by Mössbauer spectroscopy of the gamma-irradiation effect on the pyrite in three Colombian coals are analyzed. They were exposed to different gamma-irradiation doses using a 60Co source.

  6. Measurement of the Shape of the Optical-IR Spectrum of Prompt Emission from Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Grossan, Bruce; Kistaubayev, M.; Smoot, G.; Scherr, L.

    2017-06-01

    While the afterglow phase of gamma-ray bursts (GRBs) has been extensively measured, detections of prompt emission (i.e. during bright X-gamma emission) are more limited. Some prompt optical measurements are regularly made, but these are typically in a single wide band, with limited time resolution, and no measurement of spectral shape. Some models predict a synchrotron self-absorption spectral break somewhere in the IR-optical region. Measurement of the absorption frequency would give extensive information on each burst, including the electron Lorentz factor, the radius of emission, and more (Shen & Zhang 2008). Thus far the best prompt observations have been explained invoking a variety of models, but often with a non-unique interpretation. To understand this apparently heterogeneous behavior, and to reduce the number of possible models, it is critical to add data on the optical - IR spectral shape.Long GRB prompt X-gamma emission typically lasts ~40-80 s. The Swift BAT instrument rapidly measures GRB positions to within a few arc minutes and communicates them via the internet within a few seconds. We have measured the time for a fast-moving D=700 mm telescope to point and settle to be less than 9 s anywhere on the observable sky. Therefore, the majority of prompt optical-IR emission can be measured responding to BAT positions with this telescope. In this presentation, we describe our observing and science programs, and give our design for the Burst Simultaneous Three-channel Instrument (BSTI), which uses dichroics to send eparate bands to 3 cameras. Two EMCCD cameras, give high-time resolution in B and V; a third camera with a HgCdTe sensor covers H band, allowing us to study extinguished bursts. For a total exposure time of 10 s, we find a 5 sigma sensitivity of 21.3 and 20.3 mag in B and R for 1" seeing and Kitt Peak sky brightness, much fainter than typical previous prompt detections. We estimate 5 sigma H-band sensitivity for an IR optimized telescope to be

  7. Rapid measurement of meat spoilage using fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Wu, Binlin; Dahlberg, Kevin; Gao, Xin; Smith, Jason; Bailin, Jacob

    2017-02-01

    Food spoilage is mainly caused by microorganisms, such as bacteria. In this study, we measure the autofluorescence in meat samples longitudinally over a week in an attempt to develop a method to rapidly detect meat spoilage using fluorescence spectroscopy. Meat food is a biological tissue, which contains intrinsic fluorophores, such as tryptophan, collagen, nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) etc. As meat spoils, it undergoes various morphological and chemical changes. The concentrations of the native fluorophores present in a sample may change. In particular, the changes in NADH and FAD are associated with microbial metabolism, which is the most important process of the bacteria in food spoilage. Such changes may be revealed by fluorescence spectroscopy and used to indicate the status of meat spoilage. Therefore, such native fluorophores may be unique, reliable and nonsubjective indicators for detection of spoiled meat. The results of the study show that the relative concentrations of all above fluorophores change as the meat samples kept in room temperature ( 19° C) spoil. The changes become more rapidly after about two days. For the meat samples kept in a freezer ( -12° C), the changes are much less or even unnoticeable over a-week-long storage.

  8. [Ways to improve measurement accuracy of blood glucose sensing by mid-infrared spectroscopy].

    PubMed

    Wang, Yan; Li, Ning; Xu, Kexin

    2006-06-01

    Mid-infrared (MIR) spectroscopy is applicable to blood glucose sensing without using any reagent, however, due to a result of inadequate accuracy, till now this method has not been used in clinical detection. The principle and key technologies of blood glucose sensing by MIR spectroscopy are presented in this paper. Along with our experimental results, the paper analyzes ways to enhance measurement accuracy and prediction accuracy by the following four methods: selection of optimized spectral region; application of spectra data processing method; elimination of the interference with other components in the blood, and promotion in system hardware. According to these four improving methods, we designed four experiments, i.e., strict determination of the region where glucose concentration changes most sensitively in MIR, application of genetic algorithm for wavelength selection, normalization of spectra for the purpose of enhancing measuring reproduction, and utilization of CO2 laser as light source. The results show that the measurement accuracy of blood glucose concentration is enhanced almost to a clinical detection level.

  9. Special Nuclear Material Gamma-Ray Signatures for Reachback Analysts

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Karpius, Peter Joseph; Myers, Steven Charles

    2016-08-29

    These are slides on special nuclear material gamma-ray signatures for reachback analysts for an LSS Spectroscopy course. The closing thoughts for this presentation are the following: SNM materials have definite spectral signatures that should be readily recognizable to analysts in both bare and shielded configurations. One can estimate burnup of plutonium using certain pairs of peaks that are a few keV apart. In most cases, one cannot reliably estimate uranium enrichment in an analogous way to the estimation of plutonium burnup. The origin of the most intense peaks from some SNM items may be indirect and from ‘associated nuclides.' Indirectmore » SNM signatures sometimes have commonalities with the natural gamma-ray background.« less

  10. Wetting characteristics and blood clotting on surfaces of copoly(gamma-Benzyl-L-glutamate, gamma-hydroxyethyl-L-glutamine).

    PubMed

    Yano, E; Komai, T; Kawasaki, T; Kaifu, K; Atsuta, T; Kubo, Y; Fujiwara, Y

    1985-09-01

    The film surface of poly(gamma-benzyl-L-glutamate) (PBLG) was modified with 2-aminoethanol to enhance its hydrophilicity. Controlling the reaction conditions of PBLG and 2-aminoethanol, various types of copoly(gamma-benzyl-L-glutamate, gamma-hydroxyethyl-L-glutamine) film surfaces were obtained. Surface free energy (gamma sv), the dispersive component of gamma sv (gamma dsv), the nondispersive component of gamma sv (gamma psv), and the interfacial free energy of polymer surface with water (gamma sw), which were obtained by using the contact angle measurement and calculation method proposed by Andrade et al., were changed remarkably by the aminolysis. The gamma sv value increased after 2 h of aminolysis from 48.2 (PBLG) to 65.3 dyn/cm and gradually increased to around 70 dyn/cm after 12 h reaction. (gamma dsv) and (gamma psv) changed from 31.0 and 17.2 dyn/cm (PBLG) to 26.5 and 44.3 dyn/cm, respectively. These parameters of the material surfaces, modified over 12 h reaction, were found to be similar to those of the surfaces of canine aorta, vein, and human fibrin membrane. Blood clotting times on these polymer surfaces were comparatively longer than on siliconized glass surfaces.

  11. Fourier transform infrared spectroscopic study of gamma irradiated SiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Huseynov, Elchin; Garibov, Adil; Mehdiyeva, Ravan; Huseynova, Efsane

    2018-03-01

    In the present work, nano SiO2 particles are investigated before and after gamma irradiation (25, 50, 75, 100 and 200 kGy) using Fourier transform infrared (FTIR) spectroscopy method for the wavenumber between 400-4000 cm-1. It is found that as a result of spectroscopic analysis, five new peaks have appeared after gamma radiation. Two of new obtained peaks (which are located at 687 cm-1 and 2357 cm-1 of wavenumber) were formed as a result of gamma radiation interaction with Si-O bonds. Another three new peaks (peaks appropriate to 941, 2052 and 2357 cm-1 values of wavenumber) appear as a result of interaction of water with nano SiO2 particles after gamma irradiation. It has been defined as asymmetrical bending vibration, symmetrical bending vibration, symmetrical stretching vibration and asymmetrical stretching vibration of Si-O bonds appropriate to peaks.

  12. The temperature measurement research for high-speed flow based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Di, Yue; Jin, Yi; Jiang, Hong-liang; Zhai, Chao

    2013-09-01

    Due to the particularity of the high-speed flow, in order to accurately obtain its' temperature, the measurement system should has some characteristics of not interfereing with the flow, non-contact measurement and high time resolution. The traditional measurement method cannot meet the above requirements, however the measurement method based on tunable diode laser absorption spectroscopy (TDLAS) technology can meet the requirements for high-speed flow temperature measurement. When the near-infared light of a specific frequency is through the media to be measured, it will be absorbed by the water vapor molecules and then the transmission light intensity is detected by the detector. The temperature of the water vapor which is also the high-speed flow temperature, can be accurately obtained by the Beer-Lambert law. This paper focused on the research of absorption spectrum method for high speed flow temperature measurement with the scope of 250K-500K. Firstly, spectral line selection method for low temperature measurement of high-speed flow is discussed. Selected absorption lines should be isolated and have a high peak absorption within the range of 250-500K, at the same time the interference of the other lines should be avoided, so that a high measurement accuracy can be obtained. According to the near-infrared absorption spectra characteristics of water vapor, four absorption lines at the near 1395 nm and 1409 nm are selected. Secondly, a system for the temperature measurement of the water vapor in the high-speed flow is established. Room temperature are measured through two methods, direct absorption spectroscopy (DAS) and wavelength modulation spectroscopy (WMS) ,the results show that this system can realize on-line measurement of the temperature and the measurement error is about 3%. Finally, the system will be used for temperature measurement of the high-speed flow in the shock tunnel, its feasibility of measurement is analyzed.

  13. OPERATIONAL CHARACTERISTICS OF THE ARMOUR FISSION GAS GAMMA FACILITY

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Terrell, C.W.; McElroy, W.N.

    1958-10-31

    As the reactor power level is changed frequently, the radiation levels in the gamma facility fluctuate. Data are presented to show the power dependency of the gamma dose rate and the manner of growth and decay. Additional data show the dependercy of the equilibrium gamma activity on the foel temperature and total system pressure. The final phase of the work is directed toward determining an average gamma energy by attenuation measurements with various thicknesses of several materials. The neutrou flux associated with the gas phase activity is determined by foil measurement. From the measurements of dose rate and average gammamore » energy, calculations to determine the number of curies of gas phase decay gamma activity per watt of reactor power are presented. (auth)« less

  14. SeHCAT retention values as measured with a collimated and an uncollimated gamma camera: a method comparison study.

    PubMed

    Wright, James W; Lovell, Lesley A; Gemmell, Howard G; McKiddie, Fergus; Staff, Roger T

    2013-07-01

    TauroH-23-(Se) selena-25-homocholic acid retention values are used in the diagnosis of bile acid malabsorption. The standard method for measuring values is with an uncollimated gamma camera, which can create some logistic difficulties, with other background sources of activity, which are irrelevant when a collimator is used, becoming significant. In this study we compare the retention values obtained with a collimated and an uncollimated gamma camera in phantoms and in 23 patients. Bland-Altman plots were created using the data, which showed a mean bias in retention of 0.10% in the phantom study and 0.55% in the patient study between methods. A Wilcoxon signed-rank test with the null hypothesis of zero median difference between uncollimated and collimated methods was not statistically significant to P values less than 0.05 in the patient and phantom studies. In the patient study, on using a fixed boundary of retention (10%) between positive and negative status, the status of one patient was changed from negative (12%) to positive (9%). We conclude that measurement of retention with a collimated gamma camera is similar but not identical to that of uncollimated values. The clinical significance of this shift is unclear, as the threshold of significance and the method of integrating this measure with other clinical factors into management remain unclear.

  15. Sub-nanosecond Half-life Measurement of the Yrast I{sup π}=5{sup −} State in the N=78 Nucleus {sup 136}{sub 58}Ce using Fast-timing Coincident Gamma-ray Spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Alharbi, T.; Department of Physics, Faculty of Science in Zulfi, Almajmaah University, P.O. Box 1712, 11932; Regan, P.H., E-mail: p.regan@surrey.ac.uk

    2014-06-15

    We report on the measurement of the half-life of the yrast I{sup π}=5{sup −} state in the transitional nucleus {sup 136}Ce using a combined HPGe-LaBr3(Ce) scintillator gamma-ray detection array. The measured value for the E1 decay is approximately half a nanosecond, which corresponds to an E1 decay strength of approximately 2×10{sup −6} Wu. This value is in line with single-particle type E1 decays in this mass region and suggests no sign of additional K-hindrance associated with axially symmetric quadrupole deformations observed for lighter cerium isotopes.

  16. Self-absorption theory applied to rocket measurements of the nitric oxide (1, 0) gamma band in the daytime thermosphere

    NASA Technical Reports Server (NTRS)

    Eparvier, F. G.; Barth, C. A.

    1992-01-01

    Observations of the UV fluorescent emissions of the NO (1, 0) and (0, 1) gamma bands in the lower-thermospheric dayglow, made with a sounding rocket launched on March 7, 1989 from Poker Flat, Alaska, were analyzed. The resonant (1, 0) gamma band was found to be attenuated below an altitude of about 120 km. A self-absorption model based on Holstein transmission functions was developed for the resonant (1, 0) gamma band under varying conditions of slant column density and temperature and was applied for the conditions of the rocket flight. The results of the model agreed with the measured attenuation of the band, indicating the necessity of including self-absorption theory in the analysis of satellite and rocket limb data of NO.

  17. Optimal Shape of a Gamma-ray Collimator: single vs double knife edge

    NASA Astrophysics Data System (ADS)

    Metz, Albert; Hogenbirk, Alfred

    2017-09-01

    Gamma-ray collimators in nuclear waste scanners are used for selecting a narrow vertical segment in activity measurements of waste vessels. The system that is used by NRG uses tapered slit collimators of both the single and double knife edge type. The properties of these collimators were investigated by means of Monte Carlo simulations. We found that single knife edge collimators are highly preferable for a conservative estimate of the activity of the waste vessels. These collimators show much less dependence on the angle of incidence of the radiation than double knife edge collimators. This conclusion also applies to cylindrical collimators of the single knife edge type, that are generally used in medical imaging spectroscopy.

  18. Gamma ray energy tracking in GRETINA

    NASA Astrophysics Data System (ADS)

    Lee, I. Y.

    2011-10-01

    The next generation of stable and exotic beam accelerators will provide physics opportunities to study nuclei farther away from the line of stability. However, these experiments will be more demanding on instrumentation performance. These come from the lower production rate for more exotic beams, worse beam impurities, and large beam velocity from the fragmentation and inverse reactions. Gamma-ray spectroscopy will be one of the most effective tools to study exotic nuclei. However, to fully exploit the physics reach provided by these new facilities, better gamma-ray detector will be needed. In the last 10 years, a new concept, gamma-ray energy tracking array, was developed. Tracking arrays will increase the detection sensitivity by factors of several hundred compared to current arrays used in nuclear physics research. Particularly, the capability of reconstructing the position of the interaction with millimeters resolution is needed to correct the Doppler broadening of gamma rays emitted from high velocity nuclei. GRETINA is a gamma-ray tracking array which uses 28 Ge crystals, each with 36 segments, to cover ¼ of the 4 π of the 4 π solid angle. The gamma ray tracking technique requires detailed pulse shape information from each of the segments. These pulses are digitized using 14-bit 100 MHz flash ADCs, and digital signal analysis algorithms implemented in the on-board FPGAs provides energy, time and selection of pulse traces. A digital trigger system, provided flexible trigger functions including a fast trigger output, and also allows complicated trigger decisions to be made up to 20 microseconds. Further analyzed, carried out in a computer cluster, determine the energy, time, and three-dimensional positions of all gamma-ray interactions in the array. This information is then utilized, together with the characteristics of Compton scattering and pair-production processes, to track the scattering sequences of the gamma rays. GRETINA construction is completed in

  19. Investigation of Martian H2O and CO2 via gamma-ray spectroscopy

    NASA Technical Reports Server (NTRS)

    Squyres, Steven W.; Evans, Larry G.

    1987-01-01

    The evolution and present state of water and carbon dioxide on Mars are discussed. Researchers wished to determine how effectively questions regarding the distribution of water and carbon dioxide on Mars may be addressed with orbital gamma ray spectrometer data. Several simple, multi-layer models of the Martian surface were formulated to address problems such as the ice/dust ratio of layered deposits; the distribution, depth and concentration of ground ice; the thickness of north polar perennial ice; the thickness of the carbon dioxide layer over the south polar cap; the thickness of the seasonal carbon dioxide frost cap; and the water content of the seasonal frost cap. The results indicate that the Mars Observer gamma ray spectrometer will be a powerful tool for investigating the distribution and stratigraphy of volatiles on Mars.

  20. In-Plane Impedance Spectroscopy measurements in Vanadium Dioxide thin films

    NASA Astrophysics Data System (ADS)

    Ramirez, Juan; Patino, Edgar; Schmidt, Rainer; Sharoni, Amos; Gomez, Maria; Schuller, Ivan

    2012-02-01

    In plane Impedance Spectroscopy measurements have been done in Vanadium Dioxide thin films in the range of 100 Hz to 1 MHz. Our measurements allows distinguishing between the resistive and capacitive response of the Vanadium Dioxide films across the metal-insulator transition. A non ideal RC behavior was found in our thin films from room temperature up to 334 K. Around the MIT, an increase of the total capacitance is observed. A capacitor-network model is able to reproduce the capacitance changes across the MIT. Above the MIT, the system behaves like a metal as expected, and a modified equivalent circuit is necessary to describe the impedance data adequately.

  1. Towards a standard for the dynamic measurement of pressure based on laser absorption spectroscopy

    PubMed Central

    Douglass, K O; Olson, D A

    2016-01-01

    We describe an approach for creating a standard for the dynamic measurement of pressure based on the measurement of fundamental quantum properties of molecular systems. From the linewidth and intensities of ro-vibrational transitions we plan on making an accurate determination of pressure and temperature. The goal is to achieve an absolute uncertainty for time-varying pressure of 5 % with a measurement rate of 100 kHz, which will in the future serve as a method for the traceable calibration of pressure sensors used in transient processes. To illustrate this concept we have used wavelength modulation spectroscopy (WMS), due to inherent advantages over direct absorption spectroscopy, to perform rapid measurements of carbon dioxide in order to determine the pressure. The system records the full lineshape profile of a single ro-vibrational transition of CO2 at a repetition rate of 4 kHz and with a systematic measurement uncertainty of 12 % for the linewidth measurement. A series of pressures were measured at a rate of 400 Hz (10 averages) and from these measurements the linewidth was determined with a relative uncertainty of about 0.5 % on average. The pressures measured using WMS have an average difference of 0.6 % from the absolute pressure measured with a capacitance diaphragm sensor. PMID:27881884

  2. Static and Dynamic Measurement of Dopamine Adsorption in Carbon Fiber Microelectrodes Using Electrochemical Impedance Spectroscopy.

    PubMed

    Rivera-Serrano, Nilka; Pagan, Miraida; Colón-Rodríguez, Joanisse; Fuster, Christian; Vélez, Román; Almodovar-Faria, Jose; Jiménez-Rivera, Carlos; Cunci, Lisandro

    2018-02-06

    In this study, electrochemical impedance spectroscopy was used for the first time to study the adsorption of dopamine in carbon fiber microelectrodes. In order to show a proof-of-concept, static and dynamic measurements were taken at potentials ranging from -0.4 to 0.8 V versus Ag|AgCl to demonstrate the versatility of this technique to study dopamine without the need of its oxidation. We used electrochemical impedance spectroscopy and single frequency electrochemical impedance to measure different concentrations of dopamine as low as 1 nM. Moreover, the capacitance of the microelectrodes surface was found to decrease due to dopamine adsorption, which is dependent on its concentration. The effect of dissolved oxygen and electrochemical oxidation of the surface in the detection of dopamine was also studied. Nonoxidized and oxidized carbon fiber microelectrodes were prepared and characterized by optical microscopy, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Optimum working parameters of the electrodes, such as frequency and voltage, were obtained for better measurement. Electrochemical impedance of dopamine was determined at different concentration, voltages, and frequencies. Finally, dynamic experiments were conducted using a flow cell and single frequency impedance in order to study continuous and real-time measurements of dopamine.

  3. Assessment of Annual Effective Dose for Natural Radioactivity of Gamma Emitters in Biscuit Samples in Iraq.

    PubMed

    Abojassim, Ali Abid; Al-Alasadi, Lubna A; Shitake, Ahmed R; Al-Tememie, Faeq A; Husain, Afnan A

    2015-09-01

    Biscuits are an important type of food, widely consumed by babies in Iraq and other countries. This work uses gamma spectroscopy to measure the natural radioactivity due to long-lived gamma emitters in children's biscuits; it also estimates radiation hazard indices, that is, the radium equivalent activity, the representative of gamma level index, the internal hazard index, and the annual effective dose in children. Ten samples were collected from the Iraqi market from different countries of origin. The average specific activities for (226)Ra, (232)Th, and (40)K were 9.390, 3.1213, and 214.969 Bq/kg, respectively, but the average of the radium equivalent activity and the internal hazard index were 33.101 Bq/kg and 0.107, respectively. The total average annual effective dose from consumption by adults, children, and infants is estimated to be 0.655, 1.009, and 0.875 mSv, respectively. The values found for specific activity, radiation hazard indices, and annual effective dose in all samples in this study were lower than worldwide median values for all groups; therefore, these values are found to be safe.

  4. SU-E-I-79: Source Geometry Dependence of Gamma Well-Counter Measurements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Park, M; Belanger, A; Kijewski, M

    Purpose: To determine the effect of liquid sample volume and geometry on counting efficiency in a gamma well-counter, and to assess the relative contributions of sample geometry and self-attenuation. Gamma wellcounters are standard equipment in clinical and preclinical studies, for measuring patient blood radioactivity and quantifying animal tissue uptake for tracer development and other purposes. Accurate measurements are crucial. Methods: Count rates were measured for aqueous solutions of 99m- Tc at four liquid volume values in a 1-cm-diam tube and at six volume values in a 2.2-cm-diam vial. Total activity was constant for all volumes, and data were corrected formore » decay. Count rates from a point source in air, supported by a filter paper, were measured at seven heights between 1.3 and 5.7 cm from the bottom of a tube. Results: Sample volume effects were larger for the tube than for the vial. For the tube, count efficiency relative to a 1-cc volume ranged from 1.05 at 0.05 cc to 0.84 at 3 cc. For the vial, relative count efficiency ranged from 1.02 at 0.05 cc to 0.87 at 15 cc. For the point source, count efficiency relative to 1.3 cm from the tube bottom ranged from 0.98 at 1.8 cm to 0.34 at 5.7 cm. The relative efficiency of a 3-cc liquid sample in a tube compared to a 1-cc sample is 0.84; the average relative efficiency for the solid sample in air between heights in the tube corresponding to the surfaces of those volumes (1.3 and 4.8 cm) is 0.81, implying that the major contribution to efficiency loss is geometry, rather than attenuation. Conclusion: Volume-dependent correction factors should be used for accurate quantitation radioactive of liquid samples. Solid samples should be positioned at the bottom of the tube for maximum count efficiency.« less

  5. Gamma-ray burster recurrence timescales

    NASA Technical Reports Server (NTRS)

    Schaefer, B. E.; Cline, T. L.

    1984-01-01

    Three optical transients have been found which are associated with gamma-ray bursters (GRBs). The deduced recurrence timescale for these optical transients (tau sub opt) will depend on the minimum brightness for which a flash would be detected. A detailed analysis using all available data of tau sub opt as a function of E(gamma)/E(opt) is given. For flashes similar to those found in the Harvard archives, the best estimate of tau sub opt is 0.74 years, with a 99% confidence interval from 0.23 years to 4.7 years. It is currently unclear whether the optical transients from GRBs also give rise to gamma-ray events. One way to test this association is to measure the recurrence timescale of gamma-ray events tau sub gamma. A total of 210 gamma-ray error boxes were examined and it was found that the number of observed overlaps is not significantly different from the number expected from chance coincidence. This observation can be used to place limits on tau sub gamma for an assumed luminosity function. It was found that tau sub gamma is approx. 10 yr if bursts are monoenergetic. However, if GRBs have a power law luminosity function with a wide dynamic range, then the limit is tau sub gamma 0.5 yr. Hence, the gamma-ray data do not require tau sub gamma and tau sub opt to be different.

  6. Gamma-gamma coincidence performance of LaBr 3:Ce scintillation detectors vs HPGe detectors in high count-rate scenarios

    DOE PAGES

    Drescher, A.; Yoho, M.; Landsberger, S.; ...

    2017-01-15

    In this study, a radiation detection system consisting of two cerium doped lanthanum bromide (LaBr 3:Ce) scintillation detectors in a gamma-gamma coincidence configuration has been used to demonstrate the advantages that coincident detection provides relative to a single detector, and the advantages that LaBr 3:Ce detectors provide relative to high purity germanium (HPGe) detectors. Signal to noise ratios of select photopeak pairs for these detectors have been compared to high-purity germanium (HPGe) detectors in both single and coincident detector configurations in order to quantify the performance of each detector configuration. The efficiency and energy resolution of LaBr 3:Ce detectors havemore » been determined and compared to HPGe detectors. Coincident gamma-ray pairs from the radionuclides 152Eu and 133Ba have been identified in a sample that is dominated by 137Cs. Gamma-gamma coincidence successfully reduced the Compton continuum from the large 137Cs peak, revealed several coincident gamma energies characteristic of these nuclides, and improved the signal-to-noise ratio relative to single detector measurements. LaBr 3:Ce detectors performed at count rates multiple times higher than can be achieved with HPGe detectors. The standard background spectrum consisting of peaks associated with transitions within the LaBr 3:Ce crystal has also been significantly reduced. Finally, it is shown that LaBr 3:Ce detectors have the unique capability to perform gamma-gamma coincidence measurements in very high count rate scenarios, which can potentially benefit nuclear safeguards in situ measurements of spent nuclear fuel.« less

  7. Gamma-gamma coincidence performance of LaBr 3:Ce scintillation detectors vs HPGe detectors in high count-rate scenarios

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Drescher, A.; Yoho, M.; Landsberger, S.

    In this study, a radiation detection system consisting of two cerium doped lanthanum bromide (LaBr 3:Ce) scintillation detectors in a gamma-gamma coincidence configuration has been used to demonstrate the advantages that coincident detection provides relative to a single detector, and the advantages that LaBr 3:Ce detectors provide relative to high purity germanium (HPGe) detectors. Signal to noise ratios of select photopeak pairs for these detectors have been compared to high-purity germanium (HPGe) detectors in both single and coincident detector configurations in order to quantify the performance of each detector configuration. The efficiency and energy resolution of LaBr 3:Ce detectors havemore » been determined and compared to HPGe detectors. Coincident gamma-ray pairs from the radionuclides 152Eu and 133Ba have been identified in a sample that is dominated by 137Cs. Gamma-gamma coincidence successfully reduced the Compton continuum from the large 137Cs peak, revealed several coincident gamma energies characteristic of these nuclides, and improved the signal-to-noise ratio relative to single detector measurements. LaBr 3:Ce detectors performed at count rates multiple times higher than can be achieved with HPGe detectors. The standard background spectrum consisting of peaks associated with transitions within the LaBr 3:Ce crystal has also been significantly reduced. Finally, it is shown that LaBr 3:Ce detectors have the unique capability to perform gamma-gamma coincidence measurements in very high count rate scenarios, which can potentially benefit nuclear safeguards in situ measurements of spent nuclear fuel.« less

  8. Performance measurement of HARPO: A time projection chamber as a gamma-ray telescope and polarimeter

    NASA Astrophysics Data System (ADS)

    Gros, P.; Amano, S.; Attié, D.; Baron, P.; Baudin, D.; Bernard, D.; Bruel, P.; Calvet, D.; Colas, P.; Daté, S.; Delbart, A.; Frotin, M.; Geerebaert, Y.; Giebels, B.; Götz, D.; Hashimoto, S.; Horan, D.; Kotaka, T.; Louzir, M.; Magniette, F.; Minamiyama, Y.; Miyamoto, S.; Ohkuma, H.; Poilleux, P.; Semeniouk, I.; Sizun, P.; Takemoto, A.; Yamaguchi, M.; Yonamine, R.; Wang, S.

    2018-01-01

    We analyse the performance of a gas time projection chamber (TPC) as a high-performance gamma-ray telescope and polarimeter in the e+e- pair-creation regime. We use data collected at a gamma-ray beam of known polarisation. The TPC provides two orthogonal projections (x, z) and (y, z) of the tracks induced by each conversion in the gas volume. We use a simple vertex finder in which vertices and pseudo-tracks exiting from them are identified. We study the various contributions to the single-photon angular resolution using Monte Carlo simulations, compare them with the experimental data and find that they are in excellent agreement. The distribution of the azimuthal angle of pair conversions shows a bias due to the non-cylindrical-symmetric structure of the detector. This bias would average out for a long duration exposure on a space mission, but for this pencil-beam characterisation we have ensured its accurate simulation by a double systematics-control scheme, data taking with the detector rotated at several angles with respect to the beam polarisation direction and systematics control with a non-polarised beam. We measure, for the first time, the polarisation asymmetry of a linearly polarised gamma-ray beam in the low energy pair-creation regime. This sub-GeV energy range is critical for cosmic sources as their spectra are power laws which fall quickly as a function of increasing energy. This work could pave the way to extending polarised gamma-ray astronomy beyond the MeV energy regime.

  9. Spectroscopy of luminous infrared galaxies at 2 microns: 1. The ultraluminous galaxies (L(sub IR) approximately greater than 10 (exp 12) solar luminosity)

    NASA Technical Reports Server (NTRS)

    Goldader, Jeffrey D.; Joseph, R. D.; Doyon, Rene; Sanders, D. B.

    1995-01-01

    coming from volumes optically thick even at 2 micrometers, and obscured in such a fashion that the extinctions measured using optical spectroscopy do not properly measure the true optical depths. If this is the case, then even near-infrared spectroscopy may be unable to exclude the presence of undetected powerful active galactive nuclei in the ultraluminous galaxies.

  10. Gamma signatures of the C-BORD Tagged Neutron Inspection System

    NASA Astrophysics Data System (ADS)

    Sardet, A.; Pérot, B.; Carasco, C.; Sannié, G.; Moretto, S.; Nebbia, G.; Fontana, C.; Pino, F.; Iovene, A.; Tintori, C.

    2018-01-01

    In the frame of C-BORD project (H2020 program of the EU), a Rapidly relocatable Tagged Neutron Inspection System (RRTNIS) is being developed to non-intrusively detect explosives, chemical threats, and other illicit goods in cargo containers. Material identification is performed through gamma spectroscopy, using twenty NaI detectors and four LaBr3 detectors, to determine the different elements composing the inspected item from their specific gamma signatures induced by fast neutrons. This is performed using an unfolding algorithm to decompose the energy spectrum of a suspect item, selected by X-ray radiography and on which the RRTNIS inspection is focused, on a database of pure element gamma signatures. This paper reports on simulated signatures for the NaI and LaBr3 detectors, constructed using the MCNP6 code. First experimental spectra of a few elements of interest are also presented.

  11. [A method of temperature measurement for hot forging with surface oxide based on infrared spectroscopy].

    PubMed

    Zhang, Yu-cun; Qi, Yan-de; Fu, Xian-bin

    2012-05-01

    High temperature large forging is covered with a thick oxide during forging. It leads to a big measurement data error. In this paper, a method of measuring temperature based on infrared spectroscopy is presented. It can effectively eliminate the influence of surface oxide on the measurement of temperature. The method can measure the surface temperature and emissivity of the oxide directly using the infrared spectrum. The infrared spectrum is radiated from surface oxide of forging. Then it can derive the real temperature of hot forging covered with the oxide using the heat exchange equation. In order to greatly restrain interference spectroscopy through included in the received infrared radiation spectrum, three interference filter system was proposed, and a group of optimal gap parameter values using spectral simulation were obtained. The precision of temperature measurement was improved. The experimental results show that the method can accurately measure the surface temperature of high temperature forging covered with oxide. It meets the requirements of measurement accuracy, and the temperature measurement method is feasible according to the experiment result.

  12. Measurement of the ambient gamma dose equivalent and kerma from the small 252Cf source at 1 meter and the small 60Co source at 2 meters

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Carl, W. F.

    NASA Langley Research Center requested a measurement and determination of the ambient gamma dose equivalent rate and kerma at 100 cm from the 252Cf source and determination of the ambient gamma dose equivalent rate and kerma at 200 cm from the 60Co source for the Radiation Budget Instrument Experiment (Rad-X). An Exradin A6 ion chamber with Shonka air-equivalent plastic walls in combination with a Supermax electrometer were used to measure the exposure rate and free-in-air kerma rate of the two sources at the requested distances. The measured gamma exposure, kerma, and dose equivalent rates are tabulated.

  13. Effect of gamma irradiation on the structural, mechanical and optical properties of polytetrafluoroethylene sheet

    NASA Astrophysics Data System (ADS)

    Mohammadian-Kohol, M.; Asgari, M.; Shakur, H. R.

    2018-04-01

    In this study, the effects of gamma radiation on the chemical structure, mechanical and optical properties of polytetrafluoroethylene (PTFE) sheet were investigated with various doses up to 12 kGy. The chemical changes in the structure were studied by FTIR spectroscopy. Also, effects of radiation on the different mechanical parameters such as Young's modulus, toughness, strain, and stress were studied at the maximum tolerable force and the fracture points. Furthermore, changing the various optical parameters such as absorption coefficient, Urbach energy, optical band gaps, refractive index, optical dispersion parameters and plasma resonance frequency were studied by UV-visible spectroscopy. Formation of a band at 1594 cm-1, which was belonged to double carbon bonds, indicated that chain-scission was occurred at 12 kGy gamma irradiation dose. As well, the mechanical results showed an increase in the elastic behavior of PTFE sheets and a decrease in the plastic behavior of it with absorbed dose increasing. Moreover, the results showed that gamma irradiation can effectively change the various optical properties of PTFE sheets due to different phenomena such as degradation of the main chains, occurring chain-scission, formation of free radicals and cross-linking in the polymer structure.

  14. Elpasolite Planetary Ice and Composition Spectrometer (EPICS): A Low-Resource Combined Gamma-Ray and Neutron Spectrometer for Planetary Science

    NASA Astrophysics Data System (ADS)

    Stonehill, L. C.; Coupland, D. D. S.; Dallmann, N. A.; Feldman, W. C.; Mesick, K.; Nowicki, S.; Storms, S.

    2017-12-01

    The Elpasolite Planetary Ice and Composition Spectrometer (EPICS) is an innovative, low-resource gamma-ray and neutron spectrometer for planetary science missions, enabled by new scintillator and photodetector technologies. Neutrons and gamma rays are produced by cosmic ray interactions with planetary bodies and their subsequent interactions with the near-surface materials produce distinctive energy spectra. Measuring these spectra reveals details of the planetary near-surface composition that are not accessible through any other phenomenology. EPICS will be the first planetary science instrument to fully integrate the neutron and gamma-ray spectrometers. This integration is enabled by the elpasolite family of scintillators that offer gamma-ray spectroscopy energy resolutions as good as 3% FWHM at 662 keV, thermal neutron sensitivity, and the ability to distinguish gamma-ray and neutron signals via pulse shape differences. This new detection technology will significantly reduce size, weight, and power (SWaP) while providing similar neutron performance and improved gamma energy resolution compared to previous scintillator instruments, and the ability to monitor the cosmic-ray source term. EPICS will detect scintillation light with silicon photomultipliers rather than traditional photomultiplier tubes, offering dramatic additional SWaP reduction. EPICS is under development with Los Alamos National Laboratory internal research and development funding. Here we report on the EPICS design, provide an update on the current status of the EPICS development, and discuss the expected sensitivity and performance of EPICS in several potential missions to airless bodies.

  15. IR observations in gamma-ray blazars

    NASA Technical Reports Server (NTRS)

    Mahoney, W. A.; Gautier, T. N.; Ressler, M. E.; Wallyn, P.; Durouchoux, P.; Higdon, J. C.

    1997-01-01

    The infrared photometric and spectral observation of five gamma ray blazars in coordination with the energetic gamma ray experiment telescope (EGRET) onboard the Compton Gamma Ray Observatory is reported. The infrared measurements were made with a Cassegrain infrared camera and the mid-infrared large well imager at the Mt. Palomar 5 m telescope. The emphasis is on the three blazars observed simultaneously by EGRET and the ground-based telescope during viewing period 519. In addition to the acquisition of broadband spectral measurements for direct correlation with the 100 MeV EGRET observations, near infrared images were obtained, enabling a search for intra-day variability to be carried out.

  16. Gamma astrometric measurement experiment -science and implementation

    NASA Astrophysics Data System (ADS)

    Gai, Mario; Vecchiato, Alberto; Lattanzi, Mario G.; Ligori, Sebastiano; Loreggia, Davide; Fineschi, Silvano

    GAME (Gamma Astrometric Measurement Experiment) is a mission concept taking advantage of astronomical techniques for high precision measurements of interest to Fundamental Physics, and in particular the γ parameter of the Parameterized Post-Newtonian formulation of gravi-tation theories modifying the General Relativity. A space based telescope, looking close to the Solar limb thanks to coronagraphic techniques, may implement astrometric measurements sim-ilar to those performed in the solar eclipse of 1919, when Dyson, Eddington and collaborators measured for the first time the gravitational bending of light. Simulations show that the final accuracy of GAME can reach the 10-7 level. GAME will be a decisive experiment for the understanding of gravity physics, cosmology and the Universe evolution. The observations leading to Dark Matter (e.g. galaxy rotation curves) and Dark Energy (accelerated expansion of the Universe) might be explained with a modified version of General Relativity, e.g. in which the curvature invariant R is no longer constant as in Einstein's equations, i.e. the f (R) gravity theories. A 10-7 level determination of γ will provide stringent constraints on acceptable theories. Also, high precision astrometry makes accessible other appealing measurements, e.g. the light deflection induced by the quadrupole moment of giant planets, like Jupiter or Saturn, and, by high precision determination of the orbits of Mercury and high elongation asteroids, the PPN parameter β. GAME may also carry out measurements on selected astrophysical targets, e.g. nearby, bright stars known to host companions with minimum masses in the planetary/brown dwarf regime, and orbital radii in the 3-7 AU range, which are observed by no other present or planned campaigns. GAME, also thanks to high-cadence, high-precision photometry on transit-ing exoplanet systems, will thus improve on our understanding of the actual mass distribution and multiplicity of sub-stellar companions

  17. Neutron and gamma-ray measurements on the LANL Little Boy Comet Assembly

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hankins, D.E.

    1983-09-01

    We measured the neutron and gamma-ray dose rates at various distances from the Little Boy Comet Assembly at Los Alamos National Laboratory (LANL), Los Alamos, New Mexico on April 28 and 29, 1983. The distances selected varied from 350 ft to 1860 ft from the assembly, with the latter point being located at the edge of the mesa overlooking Pajarito Canyon. We varied the power levels for the various runs but we have normalized all of them to a single power-level. We also made corrections for the variations in the power-level indicators of the assembly using data provided by LANL.

  18. QUASI-STAR JETS AS UNIDENTIFIED GAMMA-RAY SOURCES

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Czerny, Bozena; Sikora, Marek; Janiuk, Agnieszka

    2012-08-10

    Gamma-ray catalogs contain a considerable amount of unidentified sources. Many of these are located out of the Galactic plane and therefore may have extragalactic origin. Here we assume that the formation of massive black holes in galactic nuclei proceeds through a quasi-star stage and consider the possibility of jet production by such objects. Those jets would be the sources of collimated synchrotron and Compton emission, extending from radio to gamma rays. The expected lifetimes of quasi-stars are of the order of million of years while the jet luminosities, somewhat smaller than that of quasar jets, are sufficient to account formore » the unidentified gamma-ray sources. The jet emission dominates over the thermal emission of a quasi-star in all energy bands, except when the jet is not directed toward an observer. The predicted synchrotron emission peaks in the IR band, with the flux close to the limits of the available IR all sky surveys. The ratio of the gamma-ray flux to the IR flux is found to be very large ({approx}60), much larger than in BL Lac objects but reached by some radio-loud quasars. On the other hand, radio-loud quasars show broad emission lines while no such lines are expected from quasi-stars. Therefore, the differentiation between various scenarios accounting for the unidentified gamma-ray sources will be possible at the basis of the photometry and spectroscopy of the IR/optical counterparts.« less

  19. Diffuse correlation spectroscopy for non-invasive, micro-vascular cerebral blood flow measurement

    PubMed Central

    Durduran, Turgut; Yodh, Arjun G.

    2013-01-01

    Diffuse correlation spectroscopy (DCS) uses the temporal fluctuations of near-infrared (NIR) light to measure cerebral blood flow (CBF) non-invasively. Here, we provide a brief history of DCS applications in brain with an emphasis on the underlying physical ideas, common instrumentation and validation. Then we describe recent clinical research that employs DCS-measured CBF as a biomarker of patient well-being, and as an indicator of hemodynamic and metabolic response to functional stimuli. PMID:23770408

  20. Measurement of Proton-induced Radiation in Animal Tissue

    NASA Astrophysics Data System (ADS)

    Sękowski, P.; Skwira-Chalot, I.; Matulewicz, T.

    Hadron therapy, because of the dosimetric and radiobiological advantages, is more and more often used in tumour treatment. This treatment method leads also to the radioactive effects induced by energetic protons on nuclei. Nuclear reactions may lead to the production of radioactive isotopes. In the present experiment, two animal (human-like) tissue samples were irradiated with 60 MeV protons. Gamma-ray spectroscopy and lifetime measurements allowed identifying isotopes produced during the irradiation, e.g. $^{18}$F and $^{34m}$Cl.

  1. Compact, multi-exposure speckle contrast optical spectroscopy (SCOS) device for measuring deep tissue blood flow

    PubMed Central

    Dragojević, Tanja; Hollmann, Joseph L.; Tamborini, Davide; Portaluppi, Davide; Buttafava, Mauro; Culver, Joseph P.; Villa, Federica; Durduran, Turgut

    2017-01-01

    Speckle contrast optical spectroscopy (SCOS) measures absolute blood flow in deep tissue, by taking advantage of multi-distance (previously reported in the literature) or multi-exposure (reported here) approach. This method promises to use inexpensive detectors to obtain good signal-to-noise ratio, but it has not yet been implemented in a suitable manner for a mass production. Here we present a new, compact, low power consumption, 32 by 2 single photon avalanche diode (SPAD) array that has no readout noise, low dead time and has high sensitivity in low light conditions, such as in vivo measurements. To demonstrate the capability to measure blood flow in deep tissue, healthy volunteers were measured, showing no significant differences from the diffuse correlation spectroscopy. In the future, this array can be miniaturized to a low-cost, robust, battery operated wireless device paving the way for measuring blood flow in a wide-range of applications from sport injury recovery and training to, on-field concussion detection to wearables. PMID:29359106

  2. Measurement and simulation of a Compton suppression system for safeguards application

    NASA Astrophysics Data System (ADS)

    Lee, Seung Kyu; Seo, Hee; Won, Byung-Hee; Lee, Chaehun; Shin, Hee-Sung; Na, Sang-Ho; Song, Dae-Yong; Kim, Ho-Dong; Park, Geun-Il; Park, Se-Hwan

    2015-11-01

    Plutonium (Pu) contents in spent nuclear fuels, recovered uranium (U) or uranium/transuranium (U/TRU) products must be measured in order to secure the safeguardability of a pyroprocessing facility. Self-induced X-Ray fluorescence (XRF) and gamma-ray spectroscopy are useful techniques for determining Pu-to-U ratios and Pu isotope ratios of spent fuel. Photon measurements of spent nuclear fuel by using high-resolution spectrometers such as high-purity germanium (HPGe) detectors show a large continuum background in the low-energy region, which is due in large part to Compton scattering of energetic gamma rays. This paper proposes a Compton suppression system for reducing of the Compton continuum background. In the present study, the system was configured by using an HPGe main detector and a BGO (bismuth germanate: Bi4Ge3O12) guard detector. The system performances for gamma-ray measurement and XRF were evaluated by means of Monte Carlo simulations and measurements of the radiation source. The Monte Carlo N-Particle eXtended (MCNPX) simulations were performed using the same geometry as for the experiments, and considered, for exact results, the production of secondary electrons and photons. As a performance test of the Compton suppression system, the peak-to-Compton ratio, which is a figure of merit to evaluate the gamma-ray detection, was enhanced by a factor of three or more when the Compton suppression system was used.

  3. Anticonvulsant properties of alpha, gamma, and alpha, gamma-substituted gamma-butyrolactones.

    PubMed

    Klunk, W E; Covey, D F; Ferrendelli, J A

    1982-09-01

    Derivatives of gamma-butyrolactone (GBL) substituted on the alpha- and/or gamma-positions were synthesized and tested for their effects on behavior in mice, on the electroencephalographs and blood pressure of paralyzed-ventilated guinea pigs, and on electrical activity of incubated hippocampal slices. Several compounds, including alpha-ethyl-alpha-methyl GBL (alpha-EMGBL), alpha, alpha-dimethyl GBL, alpha, gamma-diethyl-alpha, gamma-dimethyl GBL, and gamma-ethyl-gamma-methyl GBL, prevented seizures induced by pentylenetetrazol, beta-ethyl-beta-methyl-gamma-butyrolactone (beta-EMGBL), picrotoxin, or all three compounds in mice and guinea pigs but had no effect on seizures induced by maximal electroshock or bicuculline. Neither gamma-hydroxybutyrate (GHB) nor alpha-isopropylidine GBL had any anticonvulsant activity. The anticonvulsant alpha-substituted compounds had a potent hypotensive effect and antagonized the hypertensive effect of beta-EMGBL, alpha-EMGBL was tested in incubated hippocampal slices and was found to depress basal activity and antagonize excitation induced by beta-EMGBL. These results demonstrate that alpha-alkyl-substituted GBL and, to a lesser extent, gamma-substituted derivatives are anticonvulsant agents and that their effects are strikingly different from those of GHB or beta-alkyl-substituted GBLs, which are epileptogenic. Possibly beta- and alpha-substituted GBLs act at the same site as agonists and antagonists, respectively.

  4. Conceptual design of the radial gamma ray spectrometers system for α particle and runaway electron measurements at ITER

    NASA Astrophysics Data System (ADS)

    Nocente, M.; Tardocchi, M.; Barnsley, R.; Bertalot, L.; Brichard, B.; Croci, G.; Brolatti, G.; Di Pace, L.; Fernandes, A.; Giacomelli, L.; Lengar, I.; Moszynski, M.; Krasilnikov, V.; Muraro, A.; Pereira, R. C.; Perelli Cippo, E.; Rigamonti, D.; Rebai, M.; Rzadkiewicz, J.; Salewski, M.; Santosh, P.; Sousa, J.; Zychor, I.; Gorini, G.

    2017-07-01

    We here present the principles and main physics capabilities behind the design of the radial gamma ray spectrometers (RGRS) system for alpha particle and runaway electron measurements at ITER. The diagnostic benefits from recent advances in gamma-ray spectrometry for tokamak plasmas and combines space and high energy resolution in a single device. The RGRS system as designed can provide information on α ~ particles on a time scale of 1/10 of the slowing down time for the ITER 500 MW full power DT scenario. Spectral observations of the 3.21 and 4.44 MeV peaks from the 9\\text{Be}≤ft(α,nγ \\right){{}12}\\text{C} reaction make the measurements sensitive to α ~ particles at characteristic resonant energies and to possible anisotropies of their slowing down distribution function. An independent assessment of the neutron rate by gamma-ray emission is also feasible. In case of runaway electrons born in disruptions with a typical duration of 100 ms, a time resolution of at least 10 ms for runaway electron studies can be achieved depending on the scenario and down to a current of 40 kA by use of external gas injection. We find that the bremsstrahlung spectrum in the MeV range from confined runaways is sensitive to the electron velocity space up to E≈ 30 -40 MeV, which allows for measurements of the energy distribution of the runaway electrons at ITER.

  5. In-beam measurement of the hydrogen hyperfine splitting and prospects for antihydrogen spectroscopy

    NASA Astrophysics Data System (ADS)

    Diermaier, M.; Jepsen, C. B.; Kolbinger, B.; Malbrunot, C.; Massiczek, O.; Sauerzopf, C.; Simon, M. C.; Zmeskal, J.; Widmann, E.

    2017-06-01

    Antihydrogen, the lightest atom consisting purely of antimatter, is an ideal laboratory to study the CPT symmetry by comparison with hydrogen. With respect to absolute precision, transitions within the ground-state hyperfine structure (GS-HFS) are most appealing by virtue of their small energy separation. ASACUSA proposed employing a beam of cold antihydrogen atoms in a Rabi-type experiment, to determine the GS-HFS in a field-free region. Here we present a measurement of the zero-field hydrogen GS-HFS using the spectroscopy apparatus of ASACUSA's antihydrogen experiment. The measured value of νHF=1,420,405,748.4(3.4) (1.6) Hz with a relative precision of 2.7 × 10-9 constitutes the most precise determination of this quantity in a beam and verifies the developed spectroscopy methods for the antihydrogen HFS experiment to the p.p.b. level. Together with the recently presented observation of antihydrogen atoms 2.7 m downstream of the production region, the prerequisites for a measurement with antihydrogen are now available within the ASACUSA collaboration.

  6. In-beam measurement of the hydrogen hyperfine splitting and prospects for antihydrogen spectroscopy.

    PubMed

    Diermaier, M; Jepsen, C B; Kolbinger, B; Malbrunot, C; Massiczek, O; Sauerzopf, C; Simon, M C; Zmeskal, J; Widmann, E

    2017-06-12

    Antihydrogen, the lightest atom consisting purely of antimatter, is an ideal laboratory to study the CPT symmetry by comparison with hydrogen. With respect to absolute precision, transitions within the ground-state hyperfine structure (GS-HFS) are most appealing by virtue of their small energy separation. ASACUSA proposed employing a beam of cold antihydrogen atoms in a Rabi-type experiment, to determine the GS-HFS in a field-free region. Here we present a measurement of the zero-field hydrogen GS-HFS using the spectroscopy apparatus of ASACUSA's antihydrogen experiment. The measured value of ν HF =1,420,405,748.4(3.4) (1.6) Hz with a relative precision of 2.7 × 10 -9 constitutes the most precise determination of this quantity in a beam and verifies the developed spectroscopy methods for the antihydrogen HFS experiment to the p.p.b. level. Together with the recently presented observation of antihydrogen atoms 2.7 m downstream of the production region, the prerequisites for a measurement with antihydrogen are now available within the ASACUSA collaboration.

  7. In-beam measurement of the hydrogen hyperfine splitting and prospects for antihydrogen spectroscopy

    PubMed Central

    Diermaier, M.; Jepsen, C. B.; Kolbinger, B.; Malbrunot, C.; Massiczek, O.; Sauerzopf, C.; Simon, M. C.; Zmeskal, J.; Widmann, E.

    2017-01-01

    Antihydrogen, the lightest atom consisting purely of antimatter, is an ideal laboratory to study the CPT symmetry by comparison with hydrogen. With respect to absolute precision, transitions within the ground-state hyperfine structure (GS-HFS) are most appealing by virtue of their small energy separation. ASACUSA proposed employing a beam of cold antihydrogen atoms in a Rabi-type experiment, to determine the GS-HFS in a field-free region. Here we present a measurement of the zero-field hydrogen GS-HFS using the spectroscopy apparatus of ASACUSA's antihydrogen experiment. The measured value of νHF=1,420,405,748.4(3.4) (1.6) Hz with a relative precision of 2.7 × 10−9 constitutes the most precise determination of this quantity in a beam and verifies the developed spectroscopy methods for the antihydrogen HFS experiment to the p.p.b. level. Together with the recently presented observation of antihydrogen atoms 2.7 m downstream of the production region, the prerequisites for a measurement with antihydrogen are now available within the ASACUSA collaboration. PMID:28604657

  8. Angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its dark matter interpretation

    DOE PAGES

    Fornasa, Mattia; Cuoco, Alessandro; Zavala, Jesús; ...

    2016-12-09

    The isotropic gamma-ray background arises from the contribution of unresolved sources, including members of confirmed source classes and proposed gamma-ray emitters such as the radiation induced by dark matter annihilation and decay. Clues about the properties of the contributing sources are imprinted in the anisotropy characteristics of the gamma-ray background. We use 81 months of Pass 7 Reprocessed data from the Fermi Large Area Telescope to perform a measurement of the anisotropy angular power spectrum of the gamma-ray background. Here, we analyze energies between 0.5 and 500 GeV, extending the range considered in the previous measurement based on 22 monthsmore » of data. We also compute, for the first time, the cross-correlation angular power spectrum between different energy bins. The derived angular spectra are compatible with being Poissonian, i.e. constant in multipole. Furthermore, the energy dependence of the anisotropy suggests that the signal is due to two populations of sources, contributing, respectively, below and above ~ 2 GeV . Finally, using data from state-of-the-art numerical simulations to model the dark matter distribution, we constrain the contribution from dark matter annihilation and decay in Galactic and extra-Galactic structures to the measured anisotropy. These constraints are competitive with those that can be derived from the average intensity of the isotropic gamma-ray background.« less

  9. Proposal for the measuring molecular velocity vector with single-pulse coherent Raman spectroscopy

    NASA Technical Reports Server (NTRS)

    She, C. Y.

    1983-01-01

    Methods for simultaneous measurements of more than one flow velocity component using coherent Raman spectroscopy are proposed. It is demonstrated that using a kilowatt broad-band probe pulse (3-30 GHz) along with a megawatt narrow-band pump pulse (approximately 100 MHz), coherent Raman signal resulting from a single laser pulse is sufficient to produce a high-resolution Raman spectrum for a velocity measurement.

  10. Unfolding the prompt gamma ray spectra measured in a Lanthanum Bromide detector using GRAVEL method

    NASA Astrophysics Data System (ADS)

    De, S.; Thomas, R. G.; Rout, P. C.; Suryanarayana, S. V.; Nayak, B. K.; Saxena, A.

    2018-02-01

    Prompt fission Upsilon -ray energy spectra in spontaneous fission of 252Cf has been measured using a 6'' LaBr3(Ce) detector. Unfolding of the measured Upsilon -ray energy spectra has been carried out using GRAVEL method. The response matrix of the detector has been simulated using GEANT4 and the unfolding of Upsilon -ray energy spectra for 60Co and 137Cs sources have been validated. This unfolding technique has then been applied to the prompt gamma spectra obtained from the spontaneous fission of 252Cf.

  11. Simulation and Measurement of Absorbed Dose from 137 Cs Gammas Using a Si Timepix Detector

    NASA Technical Reports Server (NTRS)

    Stoffle, Nicholas; Pinsky, Lawrence; Empl, Anton; Semones, Edward

    2011-01-01

    The TimePix readout chip is a hybrid pixel detector with over 65k independent pixel elements. Each pixel contains its own circuitry for charge collection, counting logic, and readout. When coupled with a Silicon detector layer, the Timepix chip is capable of measuring the charge, and thus energy, deposited in the Silicon. Measurements using a NIST traceable 137Cs gamma source have been made at Johnson Space Center using such a Si Timepix detector, and this data is compared to simulations of energy deposition in the Si layer carried out using FLUKA.

  12. Gamma ray irradiated silicon nanowires: An effective model to investigate defects at the interface of Si/SiOx

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yin, Kui; Zhao, Yi; Liu, Liangbin

    2014-01-20

    The effect of gamma ray irradiation on silicon nanowires was investigated. Here, an additional defect emerged in the gamma-ray-irradiated silicon nanowires and was confirmed with electron spin resonance spectra. {sup 29}Si nuclear magnetic resonance spectroscopy showed that irradiation doses had influence on the Q{sup 4} unit structure. This phenomenon indicated that the unique core/shell structure of silicon nanowires might contribute to induce metastable defects under gamma ray irradiation, which served as a satisfactory model to investigate defects at the interface of Si/SiOx.

  13. Liverpool Telescope Spectroscopy of the Nova Eruption from V392 Persei

    NASA Astrophysics Data System (ADS)

    Darnley, M. J.; Copperwheat, C. M.; Harvey, E. J.; Healy, M. W.

    2018-05-01

    Here we report Liverpool Telescope (LT; Steele et al. 2004) spectroscopy of the recent nova eruption (ATel #11588) from the known dwarf nova system V392 Per. A Fermi & gamma;-ray detection of the eruption has also been reported (ATel #11590) along with additional photometry (ATel #11594).

  14. Ex vivo measurement of postmortem tissue changes in the crystalline lens by Brillouin spectroscopy and confocal reflectance microscopy.

    PubMed

    Reiss, Stephan; Sperlich, K; Hovakimyan, M; Martius, P; Guthoff, R F; Stolz, H; Stachs, O

    2012-08-01

    Use of Brillouin spectroscopy in ophthalmology enables noninvasive, spatially resolved determination of the rheological properties of crystalline lens tissue. Furthermore, the Brillouin shift correlates with the protein concentration inside the lens. In vitro measurements on extracted porcine lenses demonstrate that results obtained with Brillouin spectroscopy depend strongly on time after death. The intensity of the Brillouin signal decreases significantly as early as 5 h postmortem. Moreover, the fluctuation of the Brillouin frequency shift inside the lens increases with postmortem time. Images of lens tissue taken with a confocal reflectance microscope between measurements reveal a degenerative aging process. These tissue changes correlate with our results from Brillouin spectroscopy. It is concluded that only in vivo measurements appropriately reflect the rheological properties of the eye lens and its protein concentration.

  15. Assessment of the associated particle prompt gamma neutron activation technique for total body nitrogen measurement in vivo

    USDA-ARS?s Scientific Manuscript database

    Total Body Nitrogen (TBN) can be used to estimate Total Body Protein (TBP), an important body composition component at the molecular level. A system using the associated particle technique in conjunction with prompt gamma neutron activation analysis has been developed for the measurement of TBN in ...

  16. Applications of broadband cavity enhanced spectroscopy for measurements of trace gases and aerosols

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Attwood, A. R.; Brock, C. A.; Brown, S. S.; Dube, W. P.; Flores, J. M.; Langford, A. O.; Min, K. E.; Rudich, Y.; Stutz, J.; Wagner, N.; Young, C.; Zarzana, K. J.

    2015-12-01

    Broadband cavity enhanced spectroscopy (BBCES) uses a broadband light source, optical cavity, and multichannel detector to measure light extinction with high sensitivity. This method differs from cavity ringdown spectroscopy, because it uses an inexpensive, incoherent light source and allows optical extinction to be determined simultaneously across a broad wavelength region.Spectral fitting methods can be used to retrieve multiple absorbers across the observed wavelength region. We have successfully used this method to measure glyoxal (CHOCHO), nitrous acid (HONO), and nitrogen dioxide (NO2) from ground-based and aircraft-based sampling platforms. The detection limit (2-sigma) in 5 s for retrievals of CHOCHO, HONO and NO2 is 32, 250 and 80 parts per trillion (pptv).Alternatively, gas-phase absorbers can be chemically removed to allow the accurate determination of aerosol extinction. In the laboratory, we have used the aerosol extinction measurements to determine scattering and absorption as a function of wavelength. We have deployed a ground-based field instrument to measure aerosol extinction, with a detection limit of approximately 0.2 Mm-1 in 1 min.BBCES methods are most widely used in the near-ultraviolet and visible spectral region. Recently, we have demonstrated measurements at 315-350 nm for formaldehyde (CH2O) and NO2. Extending the technique further into the ultraviolet spectral region will allow important additional measurements of trace gas species and aerosol extinction.

  17. Measurement of gamma' precipitates in a nickel-based superalloy using energy-filtered transmission electron microscopy coupled with automated segmenting techniques.

    PubMed

    Tiley, J S; Viswanathan, G B; Shiveley, A; Tschopp, M; Srinivasan, R; Banerjee, R; Fraser, H L

    2010-08-01

    Precipitates of the ordered L1(2) gamma' phase (dispersed in the face-centered cubic or FCC gamma matrix) were imaged in Rene 88 DT, a commercial multicomponent Ni-based superalloy, using energy-filtered transmission electron microscopy (EFTEM). Imaging was performed using the Cr, Co, Ni, Ti and Al elemental L-absorption edges in the energy loss spectrum. Manual and automated segmentation procedures were utilized for identification of precipitate boundaries and measurement of precipitate sizes. The automated region growing technique for precipitate identification in images was determined to measure accurately precipitate diameters. In addition, the region growing technique provided a repeatable method for optimizing segmentation techniques for varying EFTEM conditions. (c) 2010 Elsevier Ltd. All rights reserved.

  18. In situ temperature measurement of. alpha. -mercuric iodide by reflection spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nason, D.; Burger, A.

    1991-12-30

    Crystal face temperatures of single crystals of {alpha}-HgI{sub 2} growing in transparent ampules by physical vapor transport have been measured, {ital in} {ital situ}, by a novel, noncontact method which may be called reflectance spectroscopy thermometry. The method is based on the temperature dependence of the energy of the free-exciton peak as detected with a low-energy reflected beam. As presently configured, the accuracy is {plus minus}1.5 {degree}C for a slowly varying surface temperature. The method has potential for noncontact temperature measurement in some systems for which pyrometry is unsatisfactory.

  19. Preliminary Results from Outcrop-Based Spectral Gamma-Ray Measurements on the Lower Silurian Longmaxi Shale, in Chongqing and Its Adjacent Areas

    NASA Astrophysics Data System (ADS)

    Zou, C.; Nie, X.; Qiao, L.; Pan, L.; Hou, S.

    2013-12-01

    The Longmaxi Shale in the Lower Silurian has been recognized as a favorable target of shale gas exploration in Sichuan basin, China. One important feature of shale gas reservoirs is of high total organic carbon (TOC). Many studies have shown that the spectral gamma-ray measurements are positively correlated to the TOC contents. In this study, the spectral gamma ray responses of five shale outcrop profiles are measured in Chongqing and its adjacent areas, Sichuan basin. Three of the five profiles are located in Qijiang, Qianjiang and Changning in Chongqing, and the other two are located in Qilong and Houtan in Guizhou. The main lithologies of the profiles include mainly black shale, gray shale and silty shale. The spectral gamma-ray measurements provide the contents of potassium (K), uranium (U), and thorium (Th). The result of the five profiles shows that the K and Th contents of gray shale are close to the ones of black shale, while the U contents in the black shale are significantly higher than that in the other rocks. The TOC contents are estimated by using the outcrop-based measurements with an empirical formula. The result shows that the TOC contents are the highest in black shale of Changning profile. It indicates that there is a most promising exploration potential for shale gas in this area. In the future, the outcrop data will be used to construct detailed lithofacies profiles and establish relationships between lithofacies both in outcrop and the subsurface gamma-ray logs. Acknowledgment: We acknowledge the financial support of the National Natural Science Foundation of China (41274185) and the Fundamental Research Funds for the Central Universities.

  20. Gamma dosimetric parameters in some skeletal muscle relaxants

    NASA Astrophysics Data System (ADS)

    Manjunatha, H. C.

    2017-09-01

    We have studied the attenuation of gamma radiation of energy ranging from 84 keV to 1330 keV (^{170}Tm, ^{22}Na,^{137}Cs, and ^{60}Co) in some commonly used skeletal muscle relaxants such as tubocurarine chloride, gallamine triethiodide, pancuronium bromide, suxamethonium bromide and mephenesin. The mass attenuation coefficient is measured from the attenuation experiment. In the present work, we have also proposed the direct relation between mass attenuation coefficient (μ /ρ ) and mass energy absorption coefficient (μ _{en}/ρ ) based on the nonlinear fitting procedure. The gamma dosimetric parameters such as mass energy absorption coefficient (μ _{en}/ρ ), effective atomic number (Z_{eff}), effective electron density (N_{el}), specific γ-ray constant, air kerma strength and dose rate are evaluated from the measured mass attentuation coefficient. These measured gamma dosimetric parameters are compared with the theoretical values. The measured values agree with the theoretical values. The studied gamma dosimetric values for the relaxants are useful in medical physics and radiation medicine.