Science.gov

Sample records for gamma spectrum analysis

  1. Frequency spectrum analysis for spectrum stabilization in airborne gamma-ray spectrometer.

    PubMed

    Zeng, Guoqiang; Tan, Chengjun; Ge, Liangquan; Zhang, Qingxian; Gu, Yi

    2014-02-01

    Abnormal multi-crystal spectral drifts often can be observed when power on the airborne gamma-ray spectrometer. Currently, these spectral drifts of each crystal are generally eliminated through manual adjustment, which is time-consuming and labor-ineffective. To realize this quick automatic spectrum stabilization of multi-crystal, a frequency spectrum analysis method for natural gamma-ray background spectrum is put forward in this paper to replace traditional spectrum stabilization method used characteristic peak. Based on the polynomial fitting of high harmonics in frequency spectrum and gamma-ray spectral drift, it calculates overall spectral drift of natural gamma-ray spectrum and adjusts the gain of spectrometer by this spectral drift value, thus completing quick spectrum stabilization in the power on stage of spectrometer. This method requires no manual intervention and can obtain the overall spectral drift value automatically under no time-domain pre-processing to the natural gamma-ray spectra. The spectral drift value calculated by this method has an absolute error less than five channels (1024 resolution) and a relative error smaller than 0.80%, which can satisfy the quick automatic spectrum stabilization requirement when power on the airborne gamma-ray spectrometer instead of manual operation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Gamma-ray pulse height spectrum analysis on systems with multiple Ge detectors using spectrum summing

    SciTech Connect

    Killian, E.W.

    1997-11-01

    A technique has been developed at the Idaho National Engineering Laboratory to sum high resolution gamma-ray pulse spectra from systems with multiple Ge detectors. Lockheed Martin Idaho Technologies Company operates a multi-detector spectrometer configuration at the Stored Waste Examination Pilot Plant facility which is used to characterize the radionuclide contents in waste drums destined for shipment to Waste Isolation Pilot Plant. This summing technique was developed to increase the sensitivity of the system, reduce the count times required to properly quantify the radio-nuclides and provide a more consistent methodology for combining data collected from multiple detectors. In spectrometer systems with multiple detectors looking at non homogeneous waste forms it is often difficult to combine individual spectrum analysis results from each detector to obtain a meaningful result for the total waste container. This is particularly true when the counting statistics in each individual spectrum are poor. The spectrum summing technique adds the spectra collected by each detector into a single spectrum which has better counting statistics than each individual spectrum. A normal spectral analysis program can then be used to analyze the sum spectrum to obtain radio-nuclide values which have smaller errors and do not have to be further manipulated to obtain results for the total waste container. 2 refs., 2 figs.

  3. Full-spectrum analysis of natural gamma-ray spectra.

    PubMed

    Hendriks, P H; Limburg, J; de Meijer, R J

    2001-01-01

    In this paper, a new system to measure natural gamma-radiation in situ will be presented. This system combines a high-efficiency BGO scintillation detector with full-spectrum data analysis (FSA). This technique uses the (nearly) full spectral shape and the so-called 'standard spectra' to calculate the activity concentrations of 40K, 232Th and 238U present in a geological matrix (sediment, rock, etc.). We describe the FSA and the determination of the standard spectra. Standard spectra are constructed for various geometries and a comparison in intensity and shape will be made. The performance of such a system has been compared to a more traditional system, consisting of a NaI detector in combination with the 'windows' analysis. For count rates typically encountered in field experiments, the same accuracy is obtained 10-20 times faster using the new system. This allows for shorter integration times and hence shorter measurements or a better spatial resolution. The applicability of such a system will be illustrated via an example of an airborne experiment in which the new system produced results comparable to those of much larger traditional systems. This paper will conclude with a discussion of the current status of the system and an outlook for future research.

  4. TPASS: a gamma-ray spectrum analysis and isotope identification computer code

    SciTech Connect

    Dickens, J.K.

    1981-03-01

    The gamma-ray spectral data-reduction and analysis computer code TPASS is described. This computer code is used to analyze complex Ge(Li) gamma-ray spectra to obtain peak areas corrected for detector efficiencies, from which are determined gamma-ray yields. These yields are compared with an isotope gamma-ray data file to determine the contributions to the observed spectrum from decay of specific radionuclides. A complete FORTRAN listing of the code and a complex test case are given.

  5. A de-noising algorithm to improve SNR of segmented gamma scanner for spectrum analysis

    NASA Astrophysics Data System (ADS)

    Li, Huailiang; Tuo, Xianguo; Shi, Rui; Zhang, Jinzhao; Henderson, Mark Julian; Courtois, Jérémie; Yan, Minhao

    2016-05-01

    An improved threshold shift-invariant wavelet transform de-noising algorithm for high-resolution gamma-ray spectroscopy is proposed to optimize the threshold function of wavelet transforms and reduce signal resulting from pseudo-Gibbs artificial fluctuations. This algorithm was applied to a segmented gamma scanning system with large samples in which high continuum levels caused by Compton scattering are routinely encountered. De-noising data from the gamma ray spectrum measured by segmented gamma scanning system with improved, shift-invariant and traditional wavelet transform algorithms were all evaluated. The improved wavelet transform method generated significantly enhanced performance of the figure of merit, the root mean square error, the peak area, and the sample attenuation correction in the segmented gamma scanning system assays. We also found that the gamma energy spectrum can be viewed as a low frequency signal as well as high frequency noise superposition by the spectrum analysis. Moreover, a smoothed spectrum can be appropriate for straightforward automated quantitative analysis.

  6. Gamma-ray pulse height spectrum analysis on systems with multiple Ge detectors using a spectrum summing

    SciTech Connect

    Killian, E.W.

    1997-05-01

    A technique has been developed at the Idaho National Engineering Laboratory to sum high resolution gamma-ray pulse spectra from systems with multiple Ge detectors. Lockheed Martin Idaho Technologies Company operates a multi-detector spectrometer configuration at the Stored Waste Examination Pilot Plant facility which is used to characterize the radio nuclide contents in waste drums destined for shipment to Waste Isolation Pilot Plant. This summing technique was developed to increase the sensitivity of the system, reduce the count times required to properly quantify the radionuclides and provide a more consistent methodology for combining data collected from multiple detectors. In spectrometer systems with multiple detectors looking at non homogenous waste forms it is often difficult to combine individual spectrum analysis results from each detector to obtain a meaningful result for the total waste container. This is particularly true when the counting statistics in each individual spectrum are poor. The spectrum summing technique adds the spectra collected by each detector into a single spectrum which has better counting statistics than each individual spectrum. A normal spectral analysis program can then be used to analyze the sum spectrum to obtain radio nuclide values which have smaller errors and do not have to be further manipulated to obtain results for the total waste container.

  7. Design of a program in Matlab environment for gamma spectrum analysis of geological samples

    NASA Astrophysics Data System (ADS)

    Rojas, M.; Correa, R.

    2016-05-01

    In this work we present the analysis of gamma ray spectra Ammonites found in different places. One of the fossils was found near the city of Cusco (Perú) and the other in “Cajón del Maipo” in Santiago (Chile). Spectra were taken with a hyperpure germanium detector (HPGe) in an environment cooled with liquid nitrogen, with the technique of high-resolution gamma spectroscopy. A program for automatic detection and classifying of the samples was developed in Matlab. It program has the advantage of being able to make direct interventions or generalize it even more, or make it automate for specific spectra and make comparison between them. For example it can calibrate the spectrum automatically, only by giving the calibration spectrum, without the necessity of putting them. Finally, it also erases the external noise.

  8. Spectrum shape-analysis techniques applied to the Hanford Tank Farms spectral gamma logs

    SciTech Connect

    Wilson, R.D.

    1997-05-01

    Gamma-ray spectra acquired with high-energy resolution by the spectral gamma logging systems (SGLSs) at the U.S. Department of Energy Hanford Tank Farms, Richland, Washington, are being analyzed for spectral shape characteristics. These spectral shapes, together with a conventional peak-area analysis, enable an analyst not only to identify the gamma-emitting species but also to determine in many instances its spatial distribution around a borehole and to identify the presence of the bremsstrahlung-producing contaminant {sup 90}Sr. The analysis relies primarily on the results of computer simulations of gamma spectra from the predominant radionuclide {sup 137}Cs for various spatial distributions. This log analysis methodology has evolved through an examination of spectral features from spectral logs taken at the SX, BY, and U Tank Farms at the Hanford Site. Initial results determined with this technique show it is possible, in most cases, to distinguish between concentrations of {sup 137}Cs. Work is continuing by experimentally measuring shape factors, incorporating spectrum shape processing in routine log analysis, and extending the techniques to additional radionuclides.

  9. 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.

  10. Spectrum Roentgen Gamma

    NASA Astrophysics Data System (ADS)

    Predehl, P.; Pavlinsky, M.

    2014-07-01

    Spectrum Roentgen Gamma (SRG) is an X-ray astrophysical observatory, developed by Russia in collaboration with Germany. The mission will be launched in 2016 into a 6-month-period halo orbit around L2. The mission lifetime is planned to be more than seven years. While the first four years of the mission are devoted to an all sky survey, the rest of the mssion will be used for pointed observations. The payload consists of two X-ray telescopes, eROSITA and ART-XC. The eROSITA sky survey will be about 30 times more sensitive than ROSAT at energies between 0.5 and 2 keV, while in the hard band (2-8 keV) it will provide the first ever true imaging survey of the sky. The design driving science is the detection of large samples of galaxy clusters out to redshifts z>1 in order to study the large scale structure in the universe and test cosmological models including Dark Energy. ART-XC's role is to extend the energy range of eROSITA alone, thereby doubling the effective area in the critical 4-7 keV range. The harder response of ART-XC also facilitates the x-ray detection of obscured AGN. Both instruments are currently in the flight model and calibration phase.

  11. 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

  12. Proximal gamma-ray spectroscopy to predict soil properties using windows and full-spectrum analysis methods.

    PubMed

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

    2013-11-27

    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.

  13. Does the Blazar Gamma-ray Spectrum Harden with Increasing Flux? - Analysis of Nine Years of EGRET Data

    NASA Technical Reports Server (NTRS)

    Nandikotkur, Giridhar; Jahoda, Keith M.; Hartman, R. C.; Mukherjee, R.; Sreekumar, P.; Boettcher, M.

    2007-01-01

    The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) discovered gamma-ray emission from more than 67 blazars during its nine-year lifetime. We conducted an exhaustive search of the EGRET archives and selected all the blazars that were observed multiple times and were bright enough to enable a spectral analysis using standard powerlaw models. The sample consists of 18 flat-spectrum radio quasars (FSRQs), 6 low-frequency-peaked BL Lacs (LBLs) and 2 high-frequency-peaked BL Lacs (HBLs). We do not detect any clear pattern in'the variation of spectral index with flux. Some of the blazars do not show any statistical evidence for spectral variability. The spectrum hardens with increasing flux in a few cases. There is also evidence for a flux-hardness anticorrelation at lo\\v fluxes in five blazars. The well observed blazars (3C 279,3C 273, PKS 0528-i-134, PKS 1622-297, PKS 0208- 512) do not show any overall trend in the long-term spectral dependence on flux, but the sample shows a mixture of hard and soft states. We observed spectral hysteresis at weekly timescales in all the three FSRQs for which data from flares lasting for 3 approx. 4 weeks were available. All three sources show a counterclockwise rotation despite the widely different flux profiles. Hysteresis in the spectral index vs. flux space has never been observed in FSRQs in gamma-rays at weekly timescales. itre analyze the observed spectral behavior in the context of various inverse-Compton mechanisms believed to be responsible for emission in the EGRET energy range. Our analysis uses the EGRET skymaps that were regenerated to include the changes in performance during the mission.

  14. MGA (Multi-Group Analysis): A gamma-ray spectrum analysis code for determining plutonium isotopic abundances

    SciTech Connect

    Gunnink, R

    1990-04-03

    Nondestructive measurements of x-ray and gamma-ray emissions can be used to analyze a sample for plutonium. This report describes the methods and algorithms we have developed for analyzing gamma-ray spectra obtained by using a germanium detector system to accurately determine the relative abundances of various actinide isotopes in a sample. Our methodology requires no calibrations and can be used to measure virtually any size and type of plutonium sample. Measurement times can be as short as a few minutes; measurements are frequently accurate to within 1%. Our methods have been programmed into a computerized analysis code called MGA (Multi-Group Analysis). Our current versions can be run on personal computers (IBM type) and on the DEC VAX microcomputer. Spectral analysis times are usually far less than a minute. 28 refs., 26 figs., 1 tab.

  15. Atypical Laterality of Resting Gamma Oscillations in Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Maxwell, Christina R.; Villalobos, Michele E.; Schultz, Robert T.; Herpertz-Dahlmann, Beate; Konrad, Kerstin; Kohls, Gregor

    2015-01-01

    Abnormal brain oscillatory activity has been found in autism spectrum disorders (ASD) and proposed as a potential biomarker. While several studies have investigated gamma oscillations in ASD, none have examined resting gamma power across multiple brain regions. This study investigated resting gamma power using EEG in 15 boys with ASD and 18 age…

  16. Atypical Laterality of Resting Gamma Oscillations in Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Maxwell, Christina R.; Villalobos, Michele E.; Schultz, Robert T.; Herpertz-Dahlmann, Beate; Konrad, Kerstin; Kohls, Gregor

    2015-01-01

    Abnormal brain oscillatory activity has been found in autism spectrum disorders (ASD) and proposed as a potential biomarker. While several studies have investigated gamma oscillations in ASD, none have examined resting gamma power across multiple brain regions. This study investigated resting gamma power using EEG in 15 boys with ASD and 18 age…

  17. The energy spectrum for stochastic eddies with gamma distribution

    NASA Astrophysics Data System (ADS)

    Kara, Rukiye; Caglar, Mine

    2012-09-01

    Lundgren (1982) showed that strained spiral vortex model for turbulent fine structure has exponential Kolmogorov energy spectrum form. Caglar (2007) has generalized Cinlar velocity field which defined a similar structure with Lundgren vortex and computed the energy spectrum. In this study, we investigate the energy spectrum of the stochastic velocity field using Gamma distribution for small scale eddies.

  18. Full spectrum analysis in environmental monitoring.

    PubMed

    Reinhardt, Sascha

    2014-08-01

    In environmental radiation monitoring, the time-variable natural gamma radiation background complicates the nuclide identification and analysis of a gamma spectrum. A full spectrum analysis based on the noise adjusted singular value decomposition method for the description of the time-variable background and adjustment calculations is a possible analysis method, which may provide advantages compared with a peak-based analysis, if applied to a time series of gamma spectra. An analysis example is shown and discussed with a measured time series of gamma spectra obtained from a spectroscopic gamma detector with a NaI(Tl) scintillator as it is used in the environmental radiation monitoring. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Atypical laterality of resting gamma oscillations in autism spectrum disorders.

    PubMed

    Maxwell, Christina R; Villalobos, Michele E; Schultz, Robert T; Herpertz-Dahlmann, Beate; Konrad, Kerstin; Kohls, Gregor

    2015-02-01

    Abnormal brain oscillatory activity has been found in autism spectrum disorders (ASD) and proposed as a potential biomarker. While several studies have investigated gamma oscillations in ASD, none have examined resting gamma power across multiple brain regions. This study investigated resting gamma power using EEG in 15 boys with ASD and 18 age and intelligence quotient matched typically developing controls. We found a decrease in resting gamma power at right lateral electrodes in ASD. We further explored associations between gamma and ASD severity as measured by the Social Responsiveness Scale (SRS) and found a negative correlation between SRS and gamma power. We believe that our findings give further support of gamma oscillations as a potential biomarker for ASD.

  20. Gamma-band abnormalities as markers of autism spectrum disorders

    PubMed Central

    Rojas, Donald C.; Wilson, Lisa B.

    2014-01-01

    Summary Autism is a behaviorally diagnosed neurodevelopmental disorder with no current biomarkers with high specificity and sensitivity. Gamma-band abnormalities have been reported in many studies of autism spectrum disorders. Gamma-band activity is associated with perceptual and cognitive functions that are compromised in autism. Some gamma-band deficits have also been seen in unaffected first-degree relatives, suggesting heritability of these findings. This review covers the published literature on gamma abnormalities in autism, the proposed mechanisms underlying the deficits, and the potential for translation into new treatments. Although the utility of gamma-band metrics as diagnostic biomarkers is currently limited, such changes in autism are also useful as endophenotypes, for evaluating potential neural mechanisms, and for use as surrogate markers of treatment response to interventions. PMID:24712425

  1. Gravity in the gamma ray spectrum

    NASA Astrophysics Data System (ADS)

    Kozicki, Janek

    References K. Fruechte, ,,The gravitational force may be the result of gamma ray energy exchange", http://www.fruechtetheory.com/full.html, Fairmont, Minnesota, USA, 2007. E. Podkletnov, R. Nieminen, ,,A possibility of gravitational force shielding by bulk Y Ba2 Cu3 O7 Superconductor", Physica C, Vol. 203, p. 441, 1992. H. Yoshiki, K. Sakai, M. Ogura, T. Kawai, Y. Masuda, T. Nakajima, T. Takayama, S. Tanaka and A. Yamaguchi, ,,Observation of ultracold-neutron production by 9-˚ cold neutrons in A superfluid helium", Physical review letters, Vol. 68, No. 9, pp. 1323-1326, 1992 F.C. Witteborn, W.M. Fairbank, ,,Experimental comparison of the gravitational force on freely falling electrons and metallic electrons", Physical review letters, Vol. 19, No. 18, 1967.

  2. Dynamic spectrum of airborne gamma-rays.

    PubMed

    Minato, S

    1990-04-01

    This note describes a method of direct measurement of airborne gamma-rays primarily from 222Rn daughters using a NaI(Tl) scintillation spectrometer with lead shields. This method has the advantage of being able to maintain the system easily compared to other usual systems including a pump. The pulse-height distributions are successively fed to a floppy disk in a personal computer every unit time. The gain shifts can be corrected automatically by a computer program. This technique would be applicable to the estimation of 222Rn daughters concentration and to examination of disequilibrium between 214Pb(RaB) and 214Bi(RaC) and of those height distribution up to about 200 m. The accuracy for estimating the concentration is as good as that of the filter method.

  3. Gamma Ray Spectrum Catalogs from Idaho National Laboratory (INL)

    DOE Data Explorer

    Heath, R. L.

    Gamma-ray spectrometry is widely applied as a tool for the assay of radioactive source material to identify the isotopes present and characterize radiation fields. Beginning with the startup of the world's first high-flux beam reactor, Materials Test Reactor (MTR), INL has pioneered the development of x-ray spectrometry for use in basic nuclear research and a variety of disciplines using radioisotopes and other radiation sources. Beginning in the early 1950s, a program was instituted to make the technique a precise laboratory tool. Standards were established for detectors and nuclear electronics to promote the production of commercial laboratory spectrometers. It was also necessary to produce a comprehensive collection of standard detector response functions for individual radio nuclides to permit the use of gamma-ray spectrometers for identification of radioisotopes present in radiation sources. This led to the publication of standard measurement methodology and a set of Gamma-Ray Spectrum Catalogues. These publications, which established standards for detector systems, experimental methods and reference spectra for both NaI (Tl) scintillation detectors and Ge(Li) - Si( Li) semiconductor devices, became standard reference works, distributed worldwide. Over 40,000 copies have been distributed by the Office of Science and Technical Information (OSTI). Unfortunately, although they are still very much in demand, they are all out of print at this time. The INL is converting this large volume of data to a format which is consistent with current information technology and meets the needs of the scientific community. Three are available online with the longest being more than 800 pages in length. Plotted spectra and decay data have been converted to digital formats and updated, including decay scheme graphics. These online catalogs are: • Ge(Li)-Si(Li) Gamma Spectrum Catalog (Published 3-29-1999) • NaI(Tl) Gamma Spectrum Catalog (Published 4-1-1997) • Gamma

  4. MGA: A gamma-ray spectrum analysis code for determining plutonium isotopic abundances. Volume 3, FORTRAN listing of the GA code

    SciTech Connect

    Gunnink, R

    1991-09-01

    Nondestructive measurements of x-ray and gamma-ray emissions can be used to determine the abundances of various actinides in a sample. Volume 1 of this report describes the methods and algorithms we have developed to determine the relative isotopic abundances of actinides in a sample, by analyzing gamma-ray spectra obtained using germanium detector systems. Volume 2 is a guide to using the MGA (Multiple Group Analysis) computer program we have written to perform plutonium isotopic analyses. This report contains a listing of the FORTRAN instructions of the code.

  5. Monte Carlo simulation of pulse pile-up effect in gamma spectrum of a PGNAA system

    NASA Astrophysics Data System (ADS)

    Mowlavi, Ali Asghar; Hadizadeh Yazdi, Mohammad Hadi

    2011-12-01

    We have applied a pile-up Monte Carlo simulation code on gamma spectrum of a prompt gamma neutron activation analysis (PGNAA) system. The code has been run in nonparalyzable mode for a specific geometry of a PGNAA system with 241Am-9Be source and NaI(Tl) detector to obtain the distortion due to “pile-up” in the pulse height of gamma spectrum. The results show that the main background in the nitrogen region of interest (ROI) is due to two pile-ups. We have also evaluated the variation of count rate and total photon sampling over the Monte Carlo spectra. At high count rates, not only the nitrogen ROI but also carbon ROI, and hydrogen peak are disturbed strongly. Comparison between the results of simulations and the experimental spectra has shown a good agreement. The code could be used for other source setups and different gamma detection systems.

  6. 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.

  7. Spectrum-Roentgen-Gamma astrophysical mission

    NASA Astrophysics Data System (ADS)

    Pavlinsky, M.; Sunyaev, R.; Churazov, E.; Gilfanov, M.; Vikhlinin, A.; Hasinger, G.; Predehl, P.; Mitsuda, K.; Kelley, R.; McCammon, D.; Ohashi, T.; den Herder, J. W.; Ramsey, B.; Gubarev, M.; O'Dell, S.; Fujimoto, R.

    2008-07-01

    The Spectrum-RG (SRG) mission, to be launched in 2011, will conduct the first all-sky survey in the 0.1-15 keV band via two imaging telescope systems, eROSITA and ART-XC. These will enable the detection of about 100 thousand clusters of galaxies and the mapping of the large scale structure of the Universe. They will also discover all obscured accreting Black Holes in nearby galaxies and about >=3 million new, distant AGNs. In the course of the survey mode two sky regions around the celestial polar zones will be observed with much higher sensitivity. Then, selected sources and dedicated sky regions will be observed in a pointing mode with high sensitivity in order to investigate the nature of dark matter and dark energy. An X-Ray Calorimeter, the SXC experiment, will permit observations of the brightest clusters of galaxies with record energy resolution in pointing mode and mapping of the hot intergalactic medium in the survey mode.

  8. Gamma-ray spectrum from gravitino dark matter decay.

    PubMed

    Ibarra, Alejandro; Tran, David

    2008-02-15

    Gravitinos are very promising candidates for the cold dark matter of the Universe. Interestingly, to achieve a sufficiently long gravitino lifetime, R parity conservation is not required, thus preventing any dangerous cosmological influence of the next-to-lightest supersymmetric particle. When R parity is violated, gravitinos decay into photons and other particles with a lifetime much longer than the age of the Universe, producing a diffuse gamma-ray flux with a characteristic spectrum that could be measured in future experiments, such as GLAST or AMS-02. In this Letter we compute the energy spectrum of photons from gravitino decay and discuss its main qualitative features.

  9. Gamma ray cosmology: The extra galactic gamma spectrum and methods to detect the underlying source

    NASA Technical Reports Server (NTRS)

    Cline, David B.

    1990-01-01

    The possible sources of extragalactic gamma rays and methods to distinguish the different sources are discussed. The sources considered are early universe decays and annihilation of Particles, active galactic nuclei (AGN) sources, and baryon-antibaryon annihilation in a baryon symmetric cosmology. The energy spectrum and possible angular fluctuations due to these sources are described.

  10. A COMPREHENSIVE ANALYSIS OF FERMI GAMMA-RAY BURST DATA. II. E{sub p} EVOLUTION PATTERNS AND IMPLICATIONS FOR THE OBSERVED SPECTRUM-LUMINOSITY RELATIONS

    SciTech Connect

    Lu Ruijing; Wei Junjie; Liang Enwei; Lue Lianzhong; Zhang Binbin; Lue Houjun; Zhang Bing; Lei Weihua E-mail: zhang@physics.unlv.edu

    2012-09-10

    We present a time-resolved spectral analysis of 51 long and 11 short bright gamma-ray bursts (GRBs) observed with the Fermi/Gamma-Ray Burst Monitor, paying special attention to E{sub p} evolution within each burst. Among eight single-pulse long GRBs, five show an evolution from hard to soft, while three show intensity tracking. The multi-pulse long GRBs have more complicated patterns. Statistically, the hard-to-soft evolution pulses tend to be more asymmetric than the intensity-tracking ones, with a steeper rising wing than the falling wing. Short GRBs have E{sub p} tracking intensity exclusively with the 16 ms time-resolution analysis. We performed a simulation analysis and suggest that for at least some bursts, the late intensity-tracking pulses could be a consequence of overlapping hard-to-soft pulses. However, the fact that the intensity-tracking pattern exists in the first pulse of the multi-pulse long GRBs and some single-pulse GRBs, suggests that intensity tracking is an independent component, which may operate in some late pulses as well. For the GRBs with measured redshifts, we present a time-resolved E{sub p} - L{sub {gamma},iso} correlation analysis and show that the scatter of the correlation is comparable to that of the global Amati/Yonetoku relation. We discuss the predictions of various radiation models regarding E{sub p} evolution, as well as the possibility of a precessing jet in GRBs. The data pose a great challenge to each of these models, and hold the key to unveiling the physics behind GRB prompt emission.

  11. Analysis of rocking curve measurements of LiF flight crystals for the objective crystal spectrometer on SPECTRUM-X-GAMMA

    NASA Astrophysics Data System (ADS)

    Halm, Ingolf; Wiebicke, Hans-Joachim; Geppert, U. R.; Christensen, Finn E.; Abdali, Salim; Schnopper, Herbert W.

    1993-11-01

    The Objective Crystal Spectrometer on the SPECTRUM-X-GAMMA satellite will use three types of natural crystals LiF(220), Si(111), RAP(001), and a multilayer structure providing high-resolution X-ray spectroscopy of Fe, S, O, and C line regions of bright cosmic X-ray sources. 330 - 360 LiF(220) crystals of dimensions approximately 23 X 63 mm(superscript 2) are required to cover one side of a large (1000 X 600 mm(superscript 2)) panel, which is to be mounted in front of one of two high throughput X-ray telescopes. Rocking curves of 441 LiF(220) crystals measured by using an expanded Cu - K(alpha) (subscript 2) beam were analyzed to select the best ones for the flight model. An important parameter is the non-parallelity of the crystal lattice planes with respect to the rear side of the crystals, since it is of the same order of magnitude as the rocking curve width. By lapping the rear side to diminish the non- parallelity and selection the main parameters of the rocking curve averaged over all crystals can be improved at least by a factor of 1.6 both in full width half maximum and peak reflectivity.

  12. Gamma spectrum following neutron capture in {sup 167}Er

    SciTech Connect

    Visser, D.; Khoo, T.L.; Lister, C.J.

    1995-08-01

    Statistical decay from a highly excited state samples all the lower-lying states and, hence, provides a sensitive measure of the level density. Pairing has a major impact on the level density, e.g. creating a pair gap between the 0- and 2-quasiparticle configurations. Hence the shape of the statistical spectrum contains information on pairing, and can be used to provide information on the reduction of pairing with thermal excitation energy. For this reason, we measured the complete spectrum of {gamma}rays following thermal neutron capture in {sup 167}Er. The experiment was performed at the Brookhaven reactor using Compton-suppressed Ge detectors from TESSA. The spectrum, which was corrected for detector response and efficiency, reveals primary (first-step, high-energy) transitions up to nearly 8 MeV, secondary (last-step, lower-energy) transitions, as we as a continuous statistical component. Effort was expanded to identify all lines from contaminant sources and an upper limit of 5% was tentatively set for their contributions. The spectral shape of the statistical spectrum will be compared with theoretical spectra obtained from a calculation of pairing which accounts for a stepwise reduction of the pair correlations as the number of quasiparticles increases. The primary lines which decay directly to the near-yrast states will also be used to deduce the level densities.

  13. Production spectrum of gamma rays in interstellar space through neutral pion decay

    NASA Technical Reports Server (NTRS)

    Stephens, S. A.; Badhwar, G. D.

    1981-01-01

    A simple representation is obtained of the observed invariant cross section for the production of neutral pions in proton-proton collisions. Using this representation, the differential and integral production spectra of gamma rays in the galaxy are calculated from interactions of cosmic ray nuclei with interstellar gas. It is shown that the uncertainties in deducing interstellar proton spectrum by demodulating the observed spectrum have only a limited effect on the gamma ray spectrum. Also determined is the gamma ray production spectrum through bremsstrahlung process for a typical interstellar electron spectrum derived from the radio spectrum in the galaxy.

  14. EGRET/COMPTEL Observations of an Unusual, Steep-Spectrum Gamma-Ray Source

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Bertsch, D. L.; Hartman, R. C.; Collmar, W.; Johnson, W. N.

    1999-01-01

    During analysis of sources below the threshold of the third EGRET catalog, we have discovered a source, named GRO J1400-3956 based on the best position, with a remarkably steep spectrum. Archival analysis of COMPTEL data shows that the spectrum must have a strong turn-over in the energy range between COMPTEL and EGRET. The EGRET data show some evidence of time variability, suggesting an AGN, but the spectral change of slope is larger than that seen for most gamma-ray blazars. The sharp cutoff resembles the high-energy spectral breaks seen in some gamma-ray pulsars. There have as yet been no OSSE observations of this source.

  15. On the omnipresent background gamma radiation of the continuous spectrum

    NASA Astrophysics Data System (ADS)

    Banjanac, R.; Maletić, D.; Joković, D.; Veselinović, N.; Dragić, A.; Udovičić, V.; Aničin, I.

    2014-05-01

    The background spectrum of a germanium detector, shielded from the radiations arriving from the lower and open for the radiations arriving from the upper hemisphere, is studied by means of absorption measurements, both in a ground level and in an underground laboratory. The low-energy continuous portion of this background spectrum that peaks at around 100 keV, which is its most intense component, is found to be of very similar shape at the two locations. It is established that it is mostly due to the radiations of the real continuous spectrum, which is quite similar to the instrumental one. The intensity of this radiation is in our cases estimated to about 8000 photons/(m2s·2π·srad) in the ground level laboratory, and to about 5000 photons/(m2s·2π·srad) in the underground laboratory, at the depth of 25 m.w.e. Simulations by GEANT4 and CORSIKA demonstrate that this radiation is predominantly of terrestrial origin, due to environmental gamma radiations scattered off the materials that surround the detector (the "skyshine radiation"), and to a far less extent to cosmic rays of degraded energy.

  16. Superfine resolution acoustooptic spectrum analysis

    NASA Technical Reports Server (NTRS)

    Ansari, Homayoon; Lesh, James R.

    1991-01-01

    High resolution spectrum analysis of RF signals is required in applications such as the search for extraterrestrial intelligence, RF interference monitoring, or general purpose decomposition of signals. Sub-Hertz resolution in three-dimensional acoustooptic spectrum analysis is theoretically and experimentally demonstrated. The operation of a two-dimensional acoustooptic spectrum analyzer is extended to include time integration over a sequence of CCD frames.

  17. Superfine resolution acoustooptic spectrum analysis

    NASA Technical Reports Server (NTRS)

    Ansari, Homayoon; Lesh, James R.

    1991-01-01

    High resolution spectrum analysis of RF signals is required in applications such as the search for extraterrestrial intelligence, RF interference monitoring, or general purpose decomposition of signals. Sub-Hertz resolution in three-dimensional acoustooptic spectrum analysis is theoretically and experimentally demonstrated. The operation of a two-dimensional acoustooptic spectrum analyzer is extended to include time integration over a sequence of CCD frames.

  18. Prompt-Gamma Activation Analysis.

    PubMed

    Lindstrom, Richard M

    1993-01-01

    A permanent, full-time instrument for prompt-gamma activation analysis is nearing completion as part of the Cold Neutron Research Facility (CNRF). The design of the analytical system has been optimized for high gamma detection efficiency and low background, particularly for hydrogen. Because of the purity of the neutron beam, shielding requirements are modest and the scatter-capture background is low. As a result of a compact sample-detector geometry, the sensitivity (counting rate per gram of analyte) is a factor of four better than the existing Maryland-NIST thermal-neutron instrument at this reactor. Hydrogen backgrounds of a few micrograms have already been achieved, which promises to be of value in numerous applications where quantitative nondestructive analysis of small quantities of hydrogen in materials is necessary.

  19. Interstellar absorption lines in the spectrum of Gamma Velorum

    NASA Technical Reports Server (NTRS)

    Morton, D. C.; Bhavsar, S. P.

    1979-01-01

    Copernicus scans of selected interstellar absorption lines in the UV spectrum of Gamma Vel are analyzed, together with ground-based data, to obtain column densities for various ion states of C, N, O, Na, Mg, Al, Si, P, S, Cl, Ar, Ca, Mn, Fe, and CO. N I and O I are fitted to a single empirical curve of growth with a velocity parameter (b) of 8 km/s; Mg II, Si II, P II, S II, Mn II, and Fe II are fitted to another curve with b between 3 and 9 km/s. Abundance determinations relative to H I show that: (1) C, N, P, S, and Ar are probably close to their solar values; (2) O may be depleted by about a factor of 2; (3) Mg, Al, Si, Cl, Mn, and Fe are depleted by a factor of 4 or more: (4) Al is depleted by at least a factor of 10 in the H II region; and (5) both N V and O VI are present, but not C IV. The N V/O VI ratio implies that the electron temperature in the H II region is about 275,000 K.

  20. Towards an amplitude analysis of exclusive. gamma gamma. processes

    SciTech Connect

    Pennington, M.R.

    1988-06-01

    The potential of two photon processes to shed light on the parton content of resonances, we maintain, can only be realized in practice by moving towards an Amplitude Analysis of experimental data. By using the process ..gamma gamma.. ..-->.. ..pi pi.. as an example, the way to do this is discussed. Presently claimed uncertainties in the ..gamma gamma.. width of even the well-known f/sub 2/ (1270) are shown to be over-optimistic and the fitted couplings of the overlapping scalar states in the 1 GeV region meaningless. Only the use of Amplitude Analysis techniques on the new higher statistics data from SLAC and DESY can resolve these uncertainties and lead to definite and significant results. 37 refs., 18 figs.

  1. Primary cosmic ray energy spectrum in terms of the GAMMA muon data

    NASA Astrophysics Data System (ADS)

    Garyaka, A. P.; Martirosov, R. M.; Ter-Antonyan, S. V.; Erlykin, A. D.; Nikolskaya, N. M.; Gallant, Y. A.; Jones, L. W.; Procureur, J.

    2009-12-01

    The energy spectrum of the primary cosmic rays is obtained by conversion from the truncated muon size spectrum of EAS studied with the GAMMA array. The previously observed dependence of E on Nμtr at various zenith angles is used. It is shown that the present spectrum has the same structure (“bump”) as the spectrum determined by another independent multi-parametric energy estimation method confirming that the “bump” structure is not produced by uncertainties in our methods.

  2. Estimates of the DT Fusion Gamma Spectrum Using an Energy Thresholding Gas Cherenkov Detector

    NASA Astrophysics Data System (ADS)

    Horsfield, Colin; Rubery, Michael; Hans, Herrmann; Mack, Joseph; Young, Carl; Caldwell, Steven; Scott, Evans; Sedillo, Thomas; Kim, Yongho; Hale, Gerry; Shah, Rahul; Kirk, Miller; Wolfgang, Stoefll

    2011-10-01

    In addition to alphas and neutrons, the DT fusion reaction also produces gamma rays from the intermediate excited 5He nucleus with a small branching ratio 10E-5 gamma/n. The very small branching ratio of the gamma-rays are mitigated by the very large yields that are expected on NIF (10E+19). The excited 5He can produce gamma-rays by decay to the ground state, emitting a 16.75 MeV gamma-ray (width 0.5 MeV), or to a broad first excited state emitting a 12 MeV gamma ray (width 5 MeV). Knowledge of the relative gamma-ray BR of these two states, from which we infer the DT gamma ray spectrum, is important to making absolutely calibrated measurements on a variety of experiments. We have carried out an energy thresh-holding experiment for DT ICF implosions on the Omega laser using a Gas Cherenkov Detector, and compared the relative intensities at various thresholds with theoretical gamma spectra folded with detector response as calculated by ACCEPT and GEANT4 codes. We present recent results from this experiment, our estimate of the precision of the DT fusion gamma spectrum and the implications for the future determination of the DT gamma/n BR.

  3. Hard-spectrum gamma-ray flare from PKS 0507+17

    NASA Astrophysics Data System (ADS)

    Kreter, M.; Buson, S.

    2016-11-01

    The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux and an unusually hard gamma-ray spectrum from a source positionally consistent with PKS 0507+17 (R.A.= 05h10m02.3691s, Dec.= +18d00m41.582s, J2000.0, Johnston et al. 1995, AJ, 110, 880).

  4. Gamma-rays and neutrons as a probe of the proton spectrum during the solar flare of 1988 December 16

    NASA Technical Reports Server (NTRS)

    Dunphy, P. P.; Chupp, E. L.

    1992-01-01

    We have previously reported on high-energy gamma-rays and neutrons from the flare of 1988 December 16 detected by the Gamma-Ray Spectrometer on the SMM satellite. In this paper, we present results on gamma-ray lines seen by the same detector during this flare. Together, these measurements constitute a powerful probe of the proton spectrum that produces the flare neutrals. Analysis of the data suggests a Bessel-function proton spectrum with a shape parameter (alpha T) of 0.054 +/- 0.004 and the number of protons above 30 MeV equal to (9.0 +/- 0.9) x 10 exp 32. The number of neutrons detected from this flare is much smaller than what is predicted from an isotropic distribution of the protons, indicating that the distribution may be nonisotropic.

  5. Muon spectrum in air showers initiated by gamma rays

    NASA Technical Reports Server (NTRS)

    Stephens, S. A.; Streitmatter, R. E.

    1985-01-01

    An analytic representation for the invariant cross-section for the production of charged pions in gamma P interactions was derived by using the available cross-sections. Using this the abundance of muons in a gamma ray initiated air shower is calculated.

  6. Fermi-LAT detection of hard spectrum gamma-ray activity from the FSRQ PKS 1532+01

    NASA Astrophysics Data System (ADS)

    Ciprini, S.; Cheung, C. C.

    2015-03-01

    The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux and an unusually hard gamma-ray spectrum from a source positionally consistent with the flat spectrum radio quasar (FSRQ) PKS 1532+01 (also known as 3FGL J1534.5+0128, Acero et al.

  7. Measuring the activity of a 51Cr neutrino source based on the gamma-radiation spectrum

    NASA Astrophysics Data System (ADS)

    Gorbachev, V. V.; Gavrin, V. N.; Ibragimova, T. V.; Kalikhov, A. V.; Malyshkin, Yu. M.; Shikhin, A. A.

    2015-12-01

    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 51Cr is presented.

  8. Fermi Large Area Telescope detection of a break in the gamma-ray spectrum of the supernova remnant Cassiopeia A [Fermi-LAT detection of a break in the gamma-ray spectrum of the supernova remnant Cassiopeia A

    DOE PAGES

    Yuan, Yajie; Funk, Stefan; Jóhannesson, Gülauger; ...

    2013-12-02

    Here, we report on observations of the supernova remnant Cassiopeia A in the energy range from 100 MeV to 100 GeV using 44 months of observations from the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope. We perform a detailed spectral analysis of this source and report on a low-energy break in the spectrum atmore » $$1.72^{+1.35}_{-0.89}$$ GeV. By comparing the results with models for the gamma-ray emission, we find that hadronic emission is preferred for the GeV energy range.« less

  9. Spectrum analysis in beam diagnostics

    SciTech Connect

    Zhang, S.Y.; Weng, W.T.

    1993-04-23

    In this article, we discuss fundamentals of the spectrum analysis in beam diagnostics, where several important particle motions in a circular accelerator are considered. The properties of the Fourier transform are presented. Then the coasting and the bunched beam motion in both longitudinal and transverse are studied. The discussions are separated for the signal particle, multiple particle, and the Schottky noise cases. To demonstrate the interesting properties of the beam motion spectrum, time domain functions are generated, and then the associated spectra are calculated and plotted. In order to show the whole picture in a single plot, some data have been scaled, therefore they may not be realistic in an accelerator.

  10. Fermi large area telescope detection of a break in the gamma-ray spectrum of the supernova remnant Cassiopeia A

    SciTech Connect

    Yuan, Yajie; Funk, Stefan; Lande, Joshua; Tibaldo, Luigi; Jóhannesson, Gülauger; Uchiyama, Yasunobu E-mail: funk@slac.stanford.edu E-mail: uchiyama@slac.stanford.edu

    2013-12-20

    We report on observations of the supernova remnant Cassiopeia A in the energy range from 100 MeV to 100 GeV using 44 months of observations from the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope. We perform a detailed spectral analysis of this source and report on a low-energy break in the spectrum at 1.72{sub −0.89}{sup +1.35} GeV. By comparing the results with models for the gamma-ray emission, we find that hadronic emission is preferred for the GeV energy range.

  11. Design Spectrum Analysis in NASTRAN

    NASA Technical Reports Server (NTRS)

    Butler, T. G.

    1984-01-01

    The utility of Design Spectrum Analysis is to give a mode by mode characterization of the behavior of a design under a given loading. The theory of design spectrum is discussed after operations are explained. User instructions are taken up here in three parts: Transient Preface, Maximum Envelope Spectrum, and RMS Average Spectrum followed by a Summary Table. A single DMAP ALTER packet will provide for all parts of the design spectrum operations. The starting point for getting a modal break-down of the response to acceleration loading is the Modal Transient rigid format. After eigenvalue extraction, modal vectors need to be isolated in the full set of physical coordinates (P-sized as opposed to the D-sized vectors in RF 12). After integration for transient response the results are scanned over the solution time interval for the peak values and for the times that they occur. A module called SCAN was written to do this job, that organizes these maxima into a diagonal output matrix. The maximum amplifier in each mode is applied to the eigenvector of each mode which then reveals the maximum displacements, stresses, forces and boundary reactions that the structure will experience for a load history, mode by mode. The standard NASTRAN output processors have been modified for this task. It is required that modes be normalized to mass.

  12. Energy spectrum of extragalactic gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Protheroe, R. J.

    1985-01-01

    The result of Monte Carlo electron photon cascade calculations for propagation of gamma rays through regions of extragalactic space containing no magnetic field are given. These calculations then provide upper limits to the expected flux from extragalactic sources. Since gamma rays in the 10 to the 14th power eV to 10 to the 17th power eV energy range are of interest, interactions of electrons and photons with the 3 K microwave background radiation are considered. To obtain an upper limit to the expected gamma ray flux from sources, the intergalactic field is assumed to be so low that it can be ignored. Interactions with photons of the near-infrared background radiation are not considered here although these will have important implications for gamma rays below 10 to the 14th power eV if the near infrared background radiation is universal. Interaction lengths of electrons and photons in the microwave background radiation at a temperature of 2.96 K were calculated and are given.

  13. Fermi LAT Search for Dark Matter in Gamma-Ray Lines and the Inclusive Photon Spectrum

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Albert, A.; Baldini, L.; Barbiellini, G.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Brigida, M.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Moiseev, Alexander A.

    2012-01-01

    Dark matter particle annihilation or decay can produce monochromatic gamma-ray lines and contribute to the diffuse gamma-ray background. Flux upper limits are presented for gamma-ray spectral lines from 7 to 200 GeV and for the diffuse gamma-ray background from 4.8 GeV to 264 GeV obtained from two years of Fermi Large Area Telescope data integrated over most of the sky. We give cross section upper limits and decay lifetime lower limits for dark matter models that produce gamma-ray lines or contribute to the diffuse spectrum, including models proposed as explanations of the PAMELA and Fermi cosmic-ray data.

  14. Fermi LAT search for dark matter in gamma-ray lines and the inclusive photon spectrum

    SciTech Connect

    Ackermann, M.

    2012-07-05

    Dark matter particle annihilation or decay can produce monochromatic gamma-ray lines and contribute to the diffuse gamma-ray background. Furthermore, we present the flux upper limits for gamma-ray spectral lines from 7 to 200 GeV and for the diffuse gamma-ray background from 4.8 GeV to 264 GeV obtained from two years of Fermi Large Area Telescope data integrated over most of the sky. Here, we give cross-section upper limits and decay lifetime lower limits for dark matter models that produce gamma-ray lines or contribute to the diffuse spectrum, including models proposed as explanations of the PAMELA and Fermi cosmic-ray data.

  15. Spectrum of [gamma] rays connecting superdeformed and normal states in [sup 192]Hg

    SciTech Connect

    Henry, R.G.; Lauritsen, T.; Khoo, T.L.; Ahmad, I.; Carpenter, M.P.; Crowell, B.; Dossing, T.; Janssens, R.V.F.; Hannachi, F.; Korichi, A.; Schuck, C.; Azaiez, F.; Beausang, C.W.; Beraud, R.; Bourgeois, C.; Clark, R.M.; Deloncle, I.; Duprat, J.; Gall, B.; Hubel, H.; Joyce, M.J.; Kaci, M.; Lecoz, Y.; Meyer, M.; Paul, E.S.; Perrin, N.; Poffe, N.; Porquet, M.G.; Redon, N.; Sergolle, H.; Sharpey-Schafer, J.F.; Simpson, J.; Smith, A.G.; Wadsworth, R.; Willsau, P. Centre de Spectrometrie Nucleaire et de Spectrometrie, Institut National de Physique Nucleaire et de Physiques des Particules, Centre National de la Recherche Scientifique, F-91405 Orsay Institut de Physique Nucleaire, Institut National de Physique Nucleaire et de Physiques des Particules, Centre National de la Recherche Scientifique, F-91406 Orsay University of Liverpool, Liverpool L69 3BX Institut de Physique Nucleaire Lyon, I

    1994-08-08

    The complete spectrum of [gamma] rays following the decay of superdeformed (SD) states in [sup 192]Hg has been extracted. The spectrum, which comprises a quasicontinuous component and sharp lines, reveals the decay mechanism and defines the excitation energies of the SD band. The decay of SD states results from the coupling between a cold, ordered SD system with a hot, chaotic one with normal deformation.

  16. Fermi LAT Detection of a Hard Spectrum Gamma-ray Flare from the FSRQ S4 0954+65

    NASA Astrophysics Data System (ADS)

    Ojha, Roopesh; Carpenter, Bryce; Tanaka, Yasuyuki

    2015-02-01

    The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope has observed an unusually hard spectrum gamma-ray flare from the flat spectrum radio quasar (FSRQ) S4 0954+65 (3FGL J0958.6+6534; RA: 149.696855, Dec: +65.565227, J2000, Johnston et al. 1995, AJ, 110, 880).

  17. Progress report for the Monte-Carlo gamma-ray spectrum simulation program BSIMUL

    NASA Technical Reports Server (NTRS)

    Haywood, S. E.; Rester, A. C., Jr.

    1996-01-01

    The progress made during 1995 on the Monte-Carlo gamma-ray spectrum simulation program BSIMUL is discussed. Several features have been added, including the ability to model shields that are tapered cylinders. Several simulations were made on the Near Earth Asteroid Rendezvous detector.

  18. A measurement of the gamma-ray spectrum from the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Lizarazo, Juan Fernando

    CACTUS is a ground-based Air Cherenkov Telescope located at the Solar 2 facility in the Southern California Mojave desert. It uses an array of 168 heliostats and a camera with 80 photomultiplier tubes to detect Cherenkov radiation produced by air showers. CACTUS incorporates fast electronics together with novel techniques of time projection imaging and pattern triggering, thus improving upon the first generation sampling ACTs. Multiplexing of PMTS and heliostats allow us to collect up to 300 independent samples of a Cherenkov light front-wave. With the capability of detecting gamma rays with energies from 50 GeV up, CACTUS is poised to provide insight into very exciting new physics. In particular, measuring the Crab nebula spectrum in the energy range between 20 to 200 GeV, will allow us to define an appropriate model for the Inverse Compton lump, together with constraints on model parameters. A full analysis of the data set collected during the winter of 2005 provided us with a Crab nebula spectrum that starts under 100 GeV and goes up to a few TeV. Implications of this will be talked about.

  19. Gamma-ray spectrum of the galactic center region

    SciTech Connect

    Riegler, G.R.; Ling, J.C.; Mahoney, W.A.; Wheaton, W.A.; Jacobson, A.S.

    1985-07-01

    The Galactic center region was observed with the HEAO 3 High Resolution Gamma-Ray Spectrometer during the fall of 1979 and the spring of 1980. Between these epochs we observed (1) a statistically significant decrease in the high-energy (511 keV to approx.3 MeV) luminosity (2) a decrease in the positron annihilation line intensity, reported previously, and (3) a low positronium annihilation fraction f = 0.38 +- 0.19 during the fall of 1979. If positrons are generated by photon-photon collisions of high-energy photons, then the absence of a detected flux above 511 keV in the spring of 1980 may indicate a time delay between positron production and annihilation.

  20. An Overview of the XGAM Code and Related Software for Gamma-ray Analysis

    SciTech Connect

    Younes, W.

    2014-11-13

    The XGAM spectrum-fitting code and associated software were developed specifically to analyze the complex gamma-ray spectra that can result from neutron-induced reactions. The XGAM code is designed to fit a spectrum over the entire available gamma-ray energy range as a single entity, in contrast to the more traditional piecewise approaches. This global-fit philosophy enforces background continuity as well as consistency between local and global behavior throughout the spectrum, and in a natural way. This report presents XGAM and the suite of programs built around it with an emphasis on how they fit into an overall analysis methodology for complex gamma-ray data. An application to the analysis of time-dependent delayed gamma-ray yields from 235U fission is shown in order to showcase the codes and how they interact.

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

    SciTech Connect

    Knežević, D. 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 was 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.

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

    NASA Astrophysics Data System (ADS)

    Knežević, D.; Jovančević, N.; Krmar, M.

    2016-03-01

    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 was 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.

  3. Reproducibility of (n,γ) gamma ray spectrum in Pb under different ENDF/B releases

    NASA Astrophysics Data System (ADS)

    Kebwaro, J. M.; He, C. H.; Zhao, Y. L.

    2016-04-01

    Radiative capture reactions are of interest in shielding design and other fundamental research. In this study the reproducibility of (n,γ) reactions in Pb when cross-section data from different ENDF/B releases are used in the Monte-Carlo code, MCNP, was investigated. Pb was selected for this study because it is widely used in shielding applications where capture reactions are likely to occur. Four different neutron spectra were declared as source in the MCNP model which consisted of a simple spherical geometry. The gamma ray spectra due to the capture reactions were recorded at 10 cm from the center of the sphere. The results reveal that the gamma ray spectrum produced by ENDF/B-V is in reasonable agreement with that produced when ENDF/B-VI.6 is used. However the spectrum produced by ENDF/B-VII does not reveal any primary gamma rays in the higher energy region (E > 3 MeV). It is further observed that the intensities of the capture gamma rays produced when various releases are used differ by a some margin showing that the results are not reproducible. The generated spectra also vary with the spectrum of the source neutrons. The discrepancies observed among various ENDF/B releases could raise concerns to end users and need to be addressed properly during benchmarking calculations before the next release. The evaluation from ENDF to ACE format that is supplied with MCNP should also be examined because errors might have arisen during the evaluation.

  4. The ultraviolet spectrum of noncoronal late-type stars - The Gamma Crucis (M3.4 III) reference spectrum

    NASA Technical Reports Server (NTRS)

    Carpenter, Kenneth G.; Pesce, Joseph E.; Stencel, Robert E.; Brown, Alexander; Johansson, Sveneric

    1988-01-01

    A guide is presented to the UV spectrum of M-type giants and supergiants whose outer atmospheres contain warm chromospheres but not coronae. The M3 giant Gamma Crucis is taken as the archetype of the cooler, oxygen-rich, noncoronal stars. Line identifications and integrated line flux measurements of the chromospheric emission features seen in the 1200-3200 A range of IUE high-resolution spectra are presented. The major fluorescence processes operating in the outer atmosphere of Gamma Crucis, including eight previously unknown pumping processes and 21 new fluorescent line products, are summarized, and the enhancements of selected line strengths by 'line leakage' is discussed. A set of absorption features toward the longer wavelength end of this range is identified which can be used to characterize the radial velocity of the stellar photospheres. The applicability of the results to the spectra of noncoronal stars with different effective temperatures and gravities is discussed.

  5. Simulation of energy absorption spectrum in NaI crystal detector for multiple gamma energy using Monte Carlo method

    SciTech Connect

    Wirawan, Rahadi; Waris, Abdul; Djamal, Mitra; Handayani, Gunawan

    2015-04-16

    The spectrum of gamma energy absorption in the NaI crystal (scintillation detector) is the interaction result of gamma photon with NaI crystal, and it’s associated with the photon gamma energy incoming to the detector. Through a simulation approach, we can perform an early observation of gamma energy absorption spectrum in a scintillator crystal detector (NaI) before the experiment conducted. In this paper, we present a simulation model result of gamma energy absorption spectrum for energy 100-700 keV (i.e. 297 keV, 400 keV and 662 keV). This simulation developed based on the concept of photon beam point source distribution and photon cross section interaction with the Monte Carlo method. Our computational code has been successfully predicting the multiple energy peaks absorption spectrum, which derived from multiple photon energy sources.

  6. Multivariate analysis of gamma spectra to characterize used nuclear fuel

    NASA Astrophysics Data System (ADS)

    Coble, Jamie; Orton, Christopher; Schwantes, Jon

    2017-04-01

    The Multi-Isotope Process (MIP) Monitor provides an efficient means to monitor the process conditions in used nuclear fuel reprocessing facilities to support process verification and validation. The MIP Monitor applies multivariate analysis to gamma spectroscopy of key stages in the reprocessing stream in order to detect small changes in the gamma spectrum, which may indicate changes in process conditions. This research extends the MIP Monitor by characterizing a used fuel sample after initial dissolution according to the type of reactor of origin (pressurized or boiling water reactor; PWR and BWR, respectively), initial enrichment, burn up, and cooling time. Simulated gamma spectra were used to develop and test three fuel characterization algorithms. The classification and estimation models employed are based on the partial least squares regression (PLS) algorithm. A PLS discriminate analysis model was developed which perfectly classified reactor type for the three PWR and three BWR reactor designs studied. Locally weighted PLS models were fitted on-the-fly to estimate the remaining fuel characteristics. For the simulated gamma spectra considered, burn up was predicted with 0.1% root mean squared percent error (RMSPE) and both cooling time and initial enrichment with approximately 2% RMSPE. This approach to automated fuel characterization can be used to independently verify operator declarations of used fuel characteristics and to inform the MIP Monitor anomaly detection routines at later stages of the fuel reprocessing stream to improve sensitivity to changes in operational parameters that may indicate issues with operational control or malicious activities.

  7. Injection Locking Techniques for Spectrum Analysis

    NASA Astrophysics Data System (ADS)

    Gathma, Timothy D.; Buckwalter, James F.

    2011-04-01

    Wideband spectrum analysis supports future communication systems that reconfigure and adapt to the capacity of the spectral environment. While test equipment manufacturers offer wideband spectrum analyzers with excellent sensitivity and resolution, these spectrum analyzers typically cannot offer acceptable size, weight, and power (SWAP). CMOS integrated circuits offer the potential to fully integrate spectrum analysis capability with analog front-end circuitry and digital signal processing on a single chip. Unfortunately, CMOS lacks high-Q passives and wideband resonator tunability that is necessary for heterodyne implementations of spectrum analyzers. As an alternative to the heterodyne receiver architectures, two nonlinear methods for performing wideband, low-power spectrum analysis are presented. The first method involves injecting the spectrum of interest into an array of injection-locked oscillators. The second method employs the closed loop dynamics of both injection locking and phase locking to independently estimate the injected frequency and power.

  8. Injection Locking Techniques for Spectrum Analysis

    SciTech Connect

    Gathma, Timothy D.; Buckwalter, James F.

    2011-04-19

    Wideband spectrum analysis supports future communication systems that reconfigure and adapt to the capacity of the spectral environment. While test equipment manufacturers offer wideband spectrum analyzers with excellent sensitivity and resolution, these spectrum analyzers typically cannot offer acceptable size, weight, and power (SWAP). CMOS integrated circuits offer the potential to fully integrate spectrum analysis capability with analog front-end circuitry and digital signal processing on a single chip. Unfortunately, CMOS lacks high-Q passives and wideband resonator tunability that is necessary for heterodyne implementations of spectrum analyzers. As an alternative to the heterodyne receiver architectures, two nonlinear methods for performing wideband, low-power spectrum analysis are presented. The first method involves injecting the spectrum of interest into an array of injection-locked oscillators. The second method employs the closed loop dynamics of both injection locking and phase locking to independently estimate the injected frequency and power.

  9. MOXE: An X-ray all-sky monitor for Soviet Spectrum-X-Gamma Mission

    NASA Technical Reports Server (NTRS)

    Priedhorsky, W.; Fenimore, E. E.; Moss, C. E.; Kelley, R. L.; Holt, S. S.

    1989-01-01

    A Monitoring Monitoring X-Ray Equipment (MOXE) is being developed for the Soviet Spectrum-X-Gamma Mission. MOXE is an X-ray all-sky monitor based on array of pinhole cameras, to be provided via a collaboration between Goddard Space Flight Center and Los Alamos National Laboratory. The objectives are to alert other observers on Spectrum-X-Gamma and other platforms of interesting transient activity, and to synoptically monitor the X-ray sky and study long-term changes in X-ray binaries. MOXE will be sensitive to sources as faint as 2 milliCrab (5 sigma) in 1 day, and cover the 2 to 20 KeV band.

  10. COMPUTER ANALYSIS OF PLANAR GAMMA CAMERA IMAGES

    EPA Science Inventory



    COMPUTER ANALYSIS OF PLANAR GAMMA CAMERA IMAGES

    T Martonen1 and J Schroeter2

    1Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. EPA, Research Triangle Park, NC 27711 USA and 2Curriculum in Toxicology, Unive...

  11. The Angular Power Spectrum of BATSE 3B Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Tegmark, Max; Hartmann, Dieter H.; Briggs, Michael S.; Meegan, Charles A.

    1996-01-01

    We compute the angular power spectrum C(sub l) from the BATSE 3B catalog of 1122 gamma-ray bursts and find no evidence for clustering on any scale. These constraints bridge the entire range from small scales (which probe source clustering and burst repetition) to the largest scales (which constrain possible anisotropics from the Galactic halo or from nearby cosmological large-scale structures). We develop an analysis technique that takes the angular position errors into account. For specific clustering or repetition models, strong upper limits can be obtained down to scales l approx. equal to 30, corresponding to a couple of degrees on the sky. The minimum-variance burst weighting that we employ is visualized graphically as an all-sky map in which each burst is smeared out by an amount corresponding to its position uncertainty. We also present separate bandpass-filtered sky maps for the quadrupole term and for the multipole ranges l = 3-10 and l = 11-30, so that the fluctuations on different angular scales can be inspected separately for visual features such as localized 'hot spots' or structures aligned with the Galactic plane. These filtered maps reveal no apparent deviations from isotropy.

  12. Alpha-to-gamma phase-amplitude coupling methods and application to autism spectrum disorder.

    PubMed

    Berman, Jeffrey I; Liu, Song; Bloy, Luke; Blaskey, Lisa; Roberts, Timothy P L; Edgar, J Christopher

    2015-03-01

    Adult studies have shown that a basic property of resting-state (RS) brain activity is the coupling of posterior alpha oscillations (alpha phase) to posterior gamma oscillations (gamma amplitude). The present study examined whether this basic RS process is present in children. Given reports of abnormal parietal-occipital RS alpha in children with autism spectrum disorder (ASD), the present study examined whether RS alpha-to-gamma phase-amplitude coupling (PAC) is disrupted in ASD. Simulations presented in this study showed limitations with traditional PAC analyses. In particular, to avoid false-positive PAC findings, simulations showed the need to use a unilateral passband to filter the upper frequency band as well as the need for longer epochs of data. For the human study, eyes-closed RS magnetoencephalography data were analyzed from 25 children with ASD and 18 typically developing (TD) children with at least 60 sec of artifact-free data. Source modeling provided continuous time course data at a midline parietal-occipital source for PAC analyses. Greater alpha-to-gamma PAC was observed in ASD than TD (p<0.005). Although children with ASD had higher PAC values, in both groups gamma activity increased at the peak of the alpha oscillation. In addition, an association between alpha power and alpha-to-gamma PAC was observed in both groups, although this relationship was stronger in ASD than TD (p<0.05). Present results demonstrated that although alpha-to-gamma PAC is present in children, this basic RS process is abnormal in children with ASD. Finally, simulations and the human data highlighted the need to consider the interplay between alpha power, epoch length, and choice of signal processing methods on PAC estimates.

  13. The solar gamma ray spectrum between 4 and 8 MeV

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Kozlovsky, B.; Suri, A. N.

    1976-01-01

    The properties of nuclear gamma ray emission in the 4 to 8 MeV range were evaluated. This emission consists of broad and narrow lines resulting from nuclear reactions of energetic H, He, C and O nuclei with ambient matter. Calculations were compared with observations of the 1972, August 4 flare and show that: (1) essentially all the observed radiation in the 4 to 8 MeV region is to the superposition of broad and narrow lines of nuclear origin with almost no contribution from other mechanisms; (2) the accelerated particles in the energy region from about 10 to 100 MeV/amu have a relatively flat Energy spectrum; (3) the calculated gamma ray spectrum, obtained from an isotropic distribution of accelerated particles, fits the observed spectrum better than the spectrum derived from an anisotropic distribution for which the particles' velocity vectors point towards the photosphere; and (4) it is possible to set a stringent upper limit on the ratio of relativistic electrons to protons in flares, consistent with the small, but finite, electron-to-proton ratio in galactic cosmic rays.

  14. Radioisotope identification method for poorly resolved gamma-ray spectrum of nuclear security concern

    NASA Astrophysics Data System (ADS)

    Ninh, Giang Nguyen; Phongphaeth, Pengvanich; Nares, Chankow; Hao, Quang Nguyen

    2016-01-01

    Gamma-ray signal can be used as a fingerprint for radioisotope identification. In the context of radioactive and nuclear materials security at the border control point, the detection task can present a significant challenge due to various constraints such as the limited measurement time, the shielding conditions, and the noise interference. This study proposes a novel method to identify the signal of one or several radioisotopes from a poorly resolved gamma-ray spectrum. In this method, the noise component in the raw spectrum is reduced by the wavelet decomposition approach, and the removal of the continuum background is performed using the baseline determination algorithm. Finally, the identification of radioisotope is completed using the matrix linear regression method. The proposed method has been verified by experiments using the poorly resolved gamma-ray signals from various scenarios including single source, mixing of natural uranium with five of the most common industrial radioactive sources (57Co, 60Co, 133Ba, 137Cs, and 241Am). The preliminary results show that the proposed algorithm is comparable with the commercial method.

  15. A US Coordination Facility for the Spectrum-X-Gamma Observatory

    NASA Technical Reports Server (NTRS)

    Forman, William R.

    1999-01-01

    Spectrum-X Gamma (SXG) is a world-class, orbiting astronomical observatory, with capabilities for all-sky monitoring, polarimetry, and high resolution spectroscopy, and wavelength coverage extending from the ultraviolet (TAUVEX and FUVITA), through the x-ray (SODART and JET-X), to the hard x-ray (MART), and gamma-ray (SPIN) regimes. SXG is a multi-national mission developed under the sponsorship of the Russian Academy of Sciences, with participation from several European countries and the U.S. The U.S. involvement in SXG includes both instrumentation and data rights. The U.S. Spectrum X Gamma Coordination Facility (SXGCF) supports U.S. observers in proposing for SXG SODART observations, analyzing SXG data, and conducting archival research. The SXGCF also has the responsibility for organizing the U.S. archive of SXG data, which will eventually include approximately half of the data from most SXG instruments. This report summarizes the activities of the SXGCF scientific and technical staff during the period from Feb. 1 through July 31, 1999.

  16. Radioisotope identification method for poorly resolved gamma-ray spectrum of nuclear security concern

    SciTech Connect

    Ninh, Giang Nguyen; Phongphaeth, Pengvanich Nares, Chankow; Hao, Quang Nguyen

    2016-01-22

    Gamma-ray signal can be used as a fingerprint for radioisotope identification. In the context of radioactive and nuclear materials security at the border control point, the detection task can present a significant challenge due to various constraints such as the limited measurement time, the shielding conditions, and the noise interference. This study proposes a novel method to identify the signal of one or several radioisotopes from a poorly resolved gamma-ray spectrum. In this method, the noise component in the raw spectrum is reduced by the wavelet decomposition approach, and the removal of the continuum background is performed using the baseline determination algorithm. Finally, the identification of radioisotope is completed using the matrix linear regression method. The proposed method has been verified by experiments using the poorly resolved gamma-ray signals from various scenarios including single source, mixing of natural uranium with five of the most common industrial radioactive sources (57Co, 60Co, 133Ba, 137Cs, and 241Am). The preliminary results show that the proposed algorithm is comparable with the commercial method.

  17. Spline-based Study of the Extragalactic Background Light Spectrum using Gamma-Ray Observations

    NASA Astrophysics Data System (ADS)

    Bose, Anoushka; Rathmann-Bloch, Julia; Biteau, Jonathan; Williams, David A.

    2016-01-01

    The extragalactic background light (EBL) is made of all the light emitted by stars and galaxies throughout cosmic history. Expanding on the work of Biteau & Williams 2015, we develop a novel natural cubic spline model of the local EBL spectrum and constrain its parameters using the gamma-ray spectra of 38 blazars measured in the high-energy (HE, 0.1 to 100 GeV) and very-high-energy (VHE, 0.1 to 20 TeV) bands. Starting from this best-fit model, we then study the so-called "delta gamma" (ΔΓ) observable, defined as the difference between the VHE and HE photon indices. This second study is focused on a subset of nine BL Lac objects. The application of a scaling factor to the cosmic optical background (0.1 - 10 nm) significantly impacts the predicted ΔΓ as a function of redshift, whereas a similar modification of the cosmic infrared background (10 - 1000 nm) has no impact. We conclude that the simple delta gamma approach can only constrain part of the EBL spectrum, while a detailed study of the spectra, such as presented in the first part of this research, is needed to constrain the cosmic infrared background.

  18. Detectors for on-line prompt gamma neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Proctor, Ray; Yusuf, Siaka; Miller, Jim; Scott, Clark

    1999-02-01

    The uncertainty of the elemental analysis is one of the major factors governing the utility of on-line prompt gamma neutron activation analysis (PGNAA) in the blending and sorting of bulk materials. In this paper, a method for quantifying the relative uncertainty from full spectrum analysis on complex materials is presented. The method was applied to three different detector types, NaI, HPGe, and BGO. The results show that the 5-10 times higher detection efficiency of a large size scintillation detector can often outweigh the resolution superiority of a HPGe detector for simple to medium complex bulk materials. The better detector resolution of sodium iodide gave a significantly lower analysis uncertainty than BGO for equal efficiency detectors.

  19. Fermi-LAT detection of hard spectrum gamma-ray flare from FSRQ S4 1800+44

    NASA Astrophysics Data System (ADS)

    Gasparrini, D.; Buson, S.

    2016-03-01

    The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux and an unusually hard gamma-ray spectrum from a source positionally consistent with the flat spectrum radio quasar (FSRQ) S4 1800+44 (also known as 3FGL J1801.5+4403, Acero et al. 2015, ApJS, 218, 23) with radio counterpart coordinates (J2000.0), R.A. = 270.3846454 deg, Dec. = 44.0727500 deg (Johnston et al. 1995, AJ, 110, 880).

  20. Technical Note: Monte Carlo study of (106) Ru/(106) Rh ophthalmic plaques including the (106) Rh gamma spectrum.

    PubMed

    Hermida-López, Marcelino; Brualla, Lorenzo

    2017-06-01

    To assess the influence of the (106) Rh gamma spectrum on the Monte Carlo simulation of (106) Ru/(106) Rh ophthalmic plaques, which has been neglected without a quantitative estimation in all previous publications. Simulations were run with the penelope 2014 Monte Carlo code for radiation transport. Depth-dose distributions in water were simulated for the plaque models CCA, CCC, CCX and CIA. In addition to the (106) Rh beta spectrum, all gamma components from the (106) Rh gamma spectrum were included in the simulations. Depth-dose curves were compared with those obtained without considering the (106) Rh gamma spectrum. Moreover, half-value (HVL) and tenth-value layers (TVL) were estimated for the (106) Rh gamma spectrum in water, PMMA, stainless steel and lead. Some practical radiation protection applications were discussed. Parallel computing was implemented to reduce computing time. The contribution of the (106) Rh gamma spectrum on the depth-dose curves is negligible at depths of clinical interest. The HVL and TVL of the (106) Rh gamma spectrum were found to be similar to those of (137) Cs. The air-kerma rate at 1 m for a CCA plaque in typical clinical conditions was about 0.4μGym2h-1, resulting in equivalent doses at that point elow 0.05 mSv during a treatment. The air-kerma rate would be underestimated by a factor of 5 if the (106) Rh gamma spectrum were not considered. Also, a freely available software tool was developed to ease parallelization of penelope 2014 simulations that use penmain as steering main program. The influence of the (106) Rh gamma spectrum is not relevant for clinical purposes, thus validating the common assumption from the literature. However, for simulations at large distances from the plaques, such as for radiation shielding assessment and estimation of dose to personnel, the gamma spectrum from (106) Rh must be taken into account to obtain accurate results. © 2017 American Association of Physicists in Medicine.

  1. Diffuse gamma radiation. [intensity, energy spectrum and spatial distribution from SAS 2 observations

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

    1978-01-01

    Results are reported for an investigation of the intensity, energy spectrum, and spatial distribution of the diffuse gamma radiation detected by SAS 2 away from the galactic plane in the energy range above 35 MeV. The gamma-ray data are compared with relevant data obtained at other wavelengths, including 21-cm emission, radio continuum radiation, and the limited UV and radio information on local molecular hydrogen. It is found that there are two quite distinct components to the diffuse radiation, one of which shows a good correlation with the galactic matter distribution and continuum radiation, while the other has a much steeper energy spectrum and appears to be isotropic at least on a coarse scale. The galactic component is interpreted in terms of its implications for both local and more distant regions of the Galaxy. The apparently isotropic radiation is discussed partly with regard to the constraints placed on possible models by the steep energy spectrum, the observed intensity, and an upper limit on the anisotropy.

  2. Measuring the activity of a {sup 51}Cr neutrino source based on the gamma-radiation spectrum

    SciTech Connect

    Gorbachev, V. V. Gavrin, V. N.; Ibragimova, T. V.; Kalikhov, A. V.; Malyshkin, Yu. M.; Shikhin, A. A.

    2015-12-15

    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.

  3. Exclusive Measurements of the b to s gamma Transition Rate and Photon Energy Spectrum

    SciTech Connect

    Lees, J.P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Stugu, B.; Brown, David Nathan; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; Koch, H.; Schroeder, T.; Asgeirsson, D.J.; Hearty, C.; Mattison, T.S.; McKenna, J.A.; Khan, A.; Blinov, V.E.; Buzykaev, A.R.; /more authors..

    2012-08-30

    We use 429 fb{sup -1} of e{sup +}e{sup -} collision data collected at the {Upsilon}(4S) resonance with the BABAR detector to measure the radiative transition rate of b {yields} s{gamma} with a sum of 38 exclusive final states. The inclusive branching fraction with a minimum photon energy of 1.9 GeV is found to be {Beta}({bar B} {yields} Xs{gamma}) = (3.29 {+-} 0.19 {+-} 0.48) x 10{sup -4} where the first uncertainty is statistical and the second is systematic. We also measure the first and second moments of the photon energy spectrum and extract the best fit values for the heavy-quark parameters, m{sub b} and {mu}{sub {pi}}{sup 2}, in the kinetic and shape function models.

  4. Experiences with area specific spectrum stripping of NaI(Tl) gamma spectra.

    PubMed

    Aage, H K; Korsbech, U; Bargholz, K; Bystöm, S; Wedmark, M; Thorshaug, S

    2006-01-01

    Processing of airborne and carborne gamma-ray spectra (AGS and CGS) often includes the stripping (elimination) of the signals from natural radioactivity. Hereby the net result becomes the signals from man-made radioactivity or other radiation anomalies. The parameters needed for spectrum stripping are dependent on detector size and quality as well as on the energy windows. In addition they depend on the environmental geometry including the vehicle carrying the detector. For AGS the altitude also influences the parameters. In general the stripping parameters are determined from tedious laboratory or field measurements with known sources of natural radioactivity. Stripping parameters may, however, often be calculated from the actual survey data or from data from a similar area. Both post-processing and real-time processing are possible. The technique is useful for gamma source search, for detection of radiation anomalies and for mapping of contamination levels. The use of the technique is illustrated with field exercise data.

  5. The Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived From First-Year Fermi Large Area Telescope Data

    SciTech Connect

    Abdo, A. A.

    2011-08-19

    We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called 'extra-galactic' diffuse {gamma}-ray emission (EGB). This component of the diffuse {gamma}-ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modelling of the bright foreground diffuse Galactic {gamma}-ray emission (DGE), the detected LAT sources and the solar {gamma}-ray emission. We find the spectrum of the EGB is consistent with a power law with differential spectral index {gamma} = 2.41 {+-} 0.05 and intensity, I(> 100 MeV) = (1.03 {+-} 0.17) x 10{sup -5} cm{sup -2} s{sup -1} sr{sup -1}, where the error is systematics dominated. Our EGB spectrum is featureless, less intense, and softer than that derived from EGRET data.

  6. THE {gamma}-RAY SPECTRUM OF GEMINGA AND THE INVERSE COMPTON MODEL OF PULSAR HIGH-ENERGY EMISSION

    SciTech Connect

    Lyutikov, Maxim

    2012-09-20

    We reanalyze the Fermi spectra of the Geminga and Vela pulsars. We find that the spectrum of Geminga above the break is well approximated by a simple power law without the exponential cutoff, making Geminga's spectrum similar to that of Crab. Vela's broadband {gamma}-ray spectrum is equally well fit with both the exponential cutoff and the double power-law shapes. In the broadband double power-law fits, for a typical Fermi spectrum of a bright {gamma}-ray pulsar, most of the errors accumulate due to the arbitrary parameterization of the spectral roll-off. In addition, a power law with an exponential cutoff gives an acceptable fit for the underlying double power-law spectrum for a very broad range of parameters, making such fitting procedures insensitive to the underlying Fermi photon spectrum. Our results have important implications for the mechanism of pulsar high-energy emission. A number of observed properties of {gamma}-ray pulsars-i.e., the broken power-law spectra without exponential cutoffs and stretching in the case of Crab beyond the maximal curvature limit, spectral breaks close to or exceeding the maximal breaks due to curvature emission, patterns of the relative intensities of the leading and trailing pulses in the Crab repeated in the X-ray and {gamma}-ray regions, presence of profile peaks at lower energies aligned with {gamma}-ray peaks-all point to the inverse Compton origin of the high-energy emission from majority of pulsars.

  7. RADSAT Benchmarks for Prompt Gamma Neutron Activation Analysis Measurements

    SciTech Connect

    Burns, Kimberly A.; Gesh, Christopher J.

    2011-07-01

    The accurate and efficient simulation of coupled neutron-photon problems is necessary for several important radiation detection applications. Examples include the detection of nuclear threats concealed in cargo containers and prompt gamma neutron activation analysis for nondestructive determination of elemental composition of unknown samples. High-resolution gamma-ray spectrometers are used in these applications to measure the spectrum of the emitted photon flux, which consists of both continuum and characteristic gamma rays with discrete energies. Monte Carlo transport is the most commonly used simulation tool for this type of problem, but computational times can be prohibitively long. This work explores the use of multi-group deterministic methods for the simulation of coupled neutron-photon problems. The main purpose of this work is to benchmark several problems modeled with RADSAT and MCNP to experimental data. Additionally, the cross section libraries for RADSAT are updated to include ENDF/B-VII cross sections. Preliminary findings show promising results when compared to MCNP and experimental data, but also areas where additional inquiry and testing are needed. The potential benefits and shortcomings of the multi-group-based approach are discussed in terms of accuracy and computational efficiency.

  8. Status of the Stellar X-Ray Polarimeter for the Spectrum-X-Gamma mission

    NASA Technical Reports Server (NTRS)

    Kaaret, P.; Novick, R.; Shaw, P.; Hanany, S.; Liu, Y.; Fleischman, J. R.; Siuniaev, R.; Lapshov, I.; Weisskopf, M. C.; Elsner, R. F.

    1991-01-01

    The Stellar X-Ray Polarimeter (SXRP) uses the polarization sensitivity of a graphite Bragg crystal and a lithium Thomsom scattering target to measure the polarization of X-rays from astrophysical sources. The SXRP is a focal plane detector for the Soviet-Danish SODART telescopes which will be launched on the Soviet Spectrum-X-Gamma mission. The SXRP will be the third orbiting stellar X-ray polarimeter, and should provide an order of magnitude increase in polarization sensitivity over its predecessors.

  9. Very high energy gamma-rays from flat spectrum radio quasars

    NASA Astrophysics Data System (ADS)

    Lindfors, Elina

    2015-03-01

    The detection of Flat Spectrum Radio Quasars (FSRQs) in the Very High Energy (VHE, E>100 GeV) range is challenging, mainly because of their steep soft spectra and distance. Nevertheless four FSRQs are now known to be VHE emitters. The detection of the VHE γ-rays has challenged the emission models of these sources. The sources are also found to exhibit very different behavior. I will give an overview of what is known about the VHE emission of these sources and about the multiwavelength signatures that are connected to the VHE gamma-ray emission.

  10. Development and Calibration of the ART-XC Mirror Modules for the Spectrum Rontgen Gamma Mission

    NASA Technical Reports Server (NTRS)

    Ramsey, B.; Gubarev, M.; Elsner, R.; Kolodziejczak, J.; Odell, S.; Swartz, D.; Pavlinsky, M.; Tkachenko, A.; Lapshov, I.

    2013-01-01

    The Spectrum-Röntgen-Gamma (SRG) mission is a Russian-lead X-ray astrophysical observatory that carries two co-aligned X-ray telescope systems. The primary instrument is the German-led extended ROentgen Survey with an Imaging Telescope Array (eROSITA), a 7-module X-ray telescope system that covers the energy range from 0.2-12 keV. The complementary instrument is the Astronomical Roentgen Telescope -- X-ray Concentrator (ART-XC or ART), a 7-module Xray telescope system that provides higher energy coverage, up to 30 keV.

  11. Derivative based sensitivity analysis of gamma index

    PubMed Central

    Sarkar, Biplab; Pradhan, Anirudh; Ganesh, T.

    2015-01-01

    Originally developed as a tool for patient-specific quality assurance in advanced treatment delivery methods to compare between measured and calculated dose distributions, the gamma index (γ) concept was later extended to compare between any two dose distributions. It takes into effect both the dose difference (DD) and distance-to-agreement (DTA) measurements in the comparison. Its strength lies in its capability to give a quantitative value for the analysis, unlike other methods. For every point on the reference curve, if there is at least one point in the evaluated curve that satisfies the pass criteria (e.g., δDD = 1%, δDTA = 1 mm), the point is included in the quantitative score as “pass.” Gamma analysis does not account for the gradient of the evaluated curve - it looks at only the minimum gamma value, and if it is <1, then the point passes, no matter what the gradient of evaluated curve is. In this work, an attempt has been made to present a derivative-based method for the identification of dose gradient. A mathematically derived reference profile (RP) representing the penumbral region of 6 MV 10 cm × 10 cm field was generated from an error function. A general test profile (GTP) was created from this RP by introducing 1 mm distance error and 1% dose error at each point. This was considered as the first of the two evaluated curves. By its nature, this curve is a smooth curve and would satisfy the pass criteria for all points in it. The second evaluated profile was generated as a sawtooth test profile (STTP) which again would satisfy the pass criteria for every point on the RP. However, being a sawtooth curve, it is not a smooth one and would be obviously poor when compared with the smooth profile. Considering the smooth GTP as an acceptable profile when it passed the gamma pass criteria (1% DD and 1 mm DTA) against the RP, the first and second order derivatives of the DDs (δD’, δD”) between these two curves were derived and used as the boundary

  12. Spectrum Monitoring Using SpectrumAnalysis LabVIEW Software, Nanoceptors, and Various Digitizing Solutions

    DTIC Science & Technology

    2015-02-01

    Spectrum Monitoring Using SpectrumAnalysis LabVIEW Software, Nanoceptors, and Various Digitizing Solutions by Joshua Smith ARL-TR-7217...1138 ARL-TR-7217 February 2015 Spectrum Monitoring Using SpectrumAnalysis LabVIEW Software, Nanoceptors, and Various Digitizing Solutions...REPORT TYPE Final 3. DATES COVERED (From - To) 06/2014–07/2014 4. TITLE AND SUBTITLE Spectrum Monitoring Using Spectrum Analysis LabVIEW

  13. Extragalactic gamma-ray signal from dark matter annihilation: a power spectrum based computation

    NASA Astrophysics Data System (ADS)

    Serpico, P. D.; Sefusatti, E.; Gustafsson, M.; Zaharijas, G.

    2012-03-01

    We revisit the computation of the extragalactic gamma-ray signal from cosmological dark matter annihilations. The prediction of this signal is notoriously model-dependent, due to different descriptions of the clumpiness of the dark matter distribution at small scales, responsible for an enhancement with respect to the smoothly distributed case. We show how a direct computation of this 'flux multiplier' in terms of the non-linear power spectrum offers a conceptually simpler approach and may ease some problems, such as the extrapolation issue. In fact, very simple analytical recipes to construct the power spectrum yield results similar to the popular Halo Model expectations, with a straightforward alternative estimate of errors. For this specific application, one also obviates the need of identifying (often literature-dependent) concepts entering the Halo Model, to compare different simulations.

  14. A new code for spectrometric analysis for environmental radiological surveillance on monitors focused on gamma radioactivity on aerosols

    SciTech Connect

    De Blas, Alfredo; Tapia, Carlos; Riego, Albert; Garcia, Roger; Dies, Javier; Diaz, Pedro; Toral, Juan; Batalla, Enric

    2015-07-01

    pGamma is a code developed by the NERG group of the Technical University of Catalonia - Barcelona Tech for the analysis of gamma spectra generated by the Equipment for the Continuous Measurement and Identification of Gamma Radioactivity on Aerosols with Paper Filter developed for our group and Raditel Servies company. Nowadays the code is in the process of adaptation for the monitors of the Environmental Radiological Surveillance Network of the Local Government of Catalonia (Generalitat of Catalonia), Spain. The code is a Spectrum Analysis System, it identifies the gamma emitters on the spectrum, determines its Concentration of Activity, generates alarms depending on the Activity of the emitters and generates a report. The Spectrum Analysis System includes a library with emitters of interest, NORM and artificial. The code is being used on the three stations with the aerosol monitor of the Network (Asco and Vandellos, near both Nuclear Power Plants and Barcelona). (authors)

  15. GammaLib: A New Framework for the Analysis of Astronomical Gamma-Ray Data

    NASA Astrophysics Data System (ADS)

    Knödlseder, J.

    2012-09-01

    With the advent of a new generation of telescopes (INTEGRAL, Fermi, H.E.S.S., MAGIC, VERITAS, MILAGRO) and the prospects of planned observatories such as CTA or HAWC, gamma-ray astronomy is becoming an integral part of modern astrophysical research. Analysing gamma-ray data is still a major challenge, and today relies on a large diversity of tools and software frameworks that were specifically developed for each instrument. With the goal of facilitating and unifying the analysis of gamma-ray data, we are currently developing an innovative data analysis toolbox, called the GammaLib, that enables gamma-ray data analysis in an instrument independent way. We will present the basic ideas that are behind the GammaLib, and describe its architecture and usage.

  16. Superior orientation discrimination and increased peak gamma frequency in autism spectrum conditions.

    PubMed

    Dickinson, Abigail; Bruyns-Haylett, Michael; Smith, Richard; Jones, Myles; Milne, Elizabeth

    2016-04-01

    While perception is recognized as being atypical in individuals with autism spectrum conditions (ASC), the underlying mechanisms for such atypicality are unclear. Here we test the hypothesis that individuals with ASC will show enhanced orientation discrimination compared with neurotypical observers. This prediction is based both on anecdotal report of superior discriminatory skills in ASC and also on evidence in the auditory domain that some individuals with ASC have superior pitch discrimination. In order to establish whether atypical perception might be mediated by an imbalance in the ratio of neural excitation and inhibition (E:I ratio), we also measured peak gamma frequency, which provides an indication of neural inhibition levels. Using a rigorous thresholding method, we found that orientation discrimination thresholds for obliquely oriented stimuli were significantly lower in participants with ASC. Using EEG to measure the visually induced gamma band response, we also found that peak gamma frequency was higher in participants with ASC, relative to a well-matched control group. These novel results suggest that neural inhibition may be increased in the occipital cortex of individuals with ASC. Implications for existing theories of an imbalance in the E:I ratio of ASC are discussed.

  17. Measurement of the Cosmic Diffuse Gamma-Ray Spectrum from 800 KEV to 30 Mev

    NASA Astrophysics Data System (ADS)

    Kappadath, Srinivas Cheenu

    The Cosmic Diffuse Gamma-Ray (CDG) spectrum between 800 keV and 30 MeV has been measured with the Imaging Compton telescope COMPTEL, aboard the Compton Gamma Ray Observatory. COMPTEL is well suited to measure the CDG flux because of its large detection area, wide field-of-view (~1.5 sr), low background and long exposure times. The major difficulty in measuring the CDG radiation at MeV energies is the intense instrumental background. The instrumental background in COMPTEL is created mainly in the surrounding material. The striking feature of the pre-COMPTEL CDG spectrum was an apparent flattening between 1 and 10 MeV. A simple power law extrapolation from the X-ray regime showed the presence of an excess, referred to as the MeV bump, in the 1 to 10 MeV range. These CDG flux measurements in the 1 to 10 MeV range are about 5 to 10 times lower than the pre-COMPTEL estimates. They show no evidence of a MeV bump in the 1 to 10 MeV range. The measured CDG emission between 0.8 and 30 MeV is well described by a power-law photon spectrum with an index of -2.4 ± 0.2 and a flux normalization of (1.05 ± 0.2) × 10-4 photons/cm2-s-sr-MeV at 5 MeV. No statistically significant deviations from isotropy is observed in the 4.2 to 30 MeV CDG emission when comparing the spectrum from the Virgo and the South Galactic Pole directions. The CDG spectrum was measured using COMPTEL data by first measuring the count rate of gamma rays from high galactic latitudes, during periods when the Earth was outside the COMPTEL field-of-view. Special data selections were applied to suppress the prompt and delayed background components. Above 4.2 MeV, in the absence of long-lived background, the count rates were extrapolated to zero cosmic-ray intensity to eliminate the prompt background and arrive at the CDG count rates. The delayed emission from long-lived radioactivity, present only below 4.2 MeV, was determined by fitting the energy spectrum. Below 4.2 MeV, their contributions were subtracted

  18. Monte Carlo models and analysis of galactic disk gamma-ray burst distributions

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon

    1989-01-01

    Gamma-ray bursts are transient astronomical phenomena which have no quiescent counterparts in any region of the electromagnetic spectrum. Although temporal and spectral properties indicate that these events are likely energetic, their unknown spatial distribution complicates astrophysical interpretation. Monte Carlo samples of gamma-ray burst sources are created which belong to Galactic disk populations. Spatial analysis techniques are used to compare these samples to the observed distribution. From this, both quantitative and qualitative conclusions are drawn concerning allowed luminosity and spatial distributions of the actual sample. Although the Burst and Transient Source Experiment (BATSE) experiment on Gamma Ray Observatory (GRO) will significantly improve knowledge of the gamma-ray burst source spatial characteristics within only a few months of launch, the analysis techniques described herein will not be superceded. Rather, they may be used with BATSE results to obtain detailed information about both the luminosity and spatial distributions of the sources.

  19. Quantitative comparison of 3D and 2.5D gamma analysis: introducing gamma angle histograms

    NASA Astrophysics Data System (ADS)

    Sa'd, M. Al; Graham, J.; Liney, G. P.; Moore, C. J.

    2013-04-01

    Comparison of dose distributions using the 3D gamma method is anticipated to provide better indicators for the quality assurance process than the 2.5D (stacked 2D slice-by-slice) gamma calculation, especially for advanced radiotherapy technologies. This study compares the accuracy of the 3D and 2.5D gamma calculation methods. 3D and 2.5D gamma calculations were carried out on four reference/evaluation 3D dose sample pairs. A number of analysis methods were used, including average gamma and gamma volume histograms. We introduce the concept of gamma-angle histograms. Noise sensitivity tests were also performed using two different noise models. The advantage of the 3D gamma method showed up as a higher proportion of points passing the tolerance criteria of 3% dose difference and 3 mm distance-to-agreement (DTA), with considerably lower average gamma values, a lower influence of the DTA criterion, and a higher noise tolerance. The 3D gamma approach is more reliable than the 2.5D approach in terms of providing comprehensive quantitative results, which are needed in quality assurance procedures for advanced radiotherapy methods.

  20. Gamma-ray Background Spectrum and Annihilation Rate in the Baryon-symmetric Big-bang Cosmology

    NASA Technical Reports Server (NTRS)

    Puget, J. L.

    1973-01-01

    An attempt was made to acquire experimental information on the problem of baryon symmetry on a large cosmological scale by observing the annihilation products. Data cover absorption cross sections and background radiation due to other sources for the two main products of annihilation, gamma rays and neutrinos. Test results show that the best direct experimental test for the presence of large scale antimatter lies in the gamma ray background spectrum between 1 and 70 MeV.

  1. Gamma-ray Background Spectrum and Annihilation Rate in the Baryon-symmetric Big-bang Cosmology

    NASA Technical Reports Server (NTRS)

    Puget, J. L.

    1973-01-01

    An attempt was made to acquire experimental information on the problem of baryon symmetry on a large cosmological scale by observing the annihilation products. Data cover absorption cross sections and background radiation due to other sources for the two main products of annihilation, gamma rays and neutrinos. Test results show that the best direct experimental test for the presence of large scale antimatter lies in the gamma ray background spectrum between 1 and 70 MeV.

  2. Development of Monte Carlo code for coincidence prompt gamma-ray neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Han, Xiaogang

    Prompt Gamma-Ray Neutron Activation Analysis (PGNAA) offers a non-destructive, relatively rapid on-line method for determination of elemental composition of bulk and other samples. However, PGNAA has an inherently large background. These backgrounds are primarily due to the presence of the neutron excitation source. It also includes neutron activation of the detector and the prompt gamma rays from the structure materials of PGNAA devices. These large backgrounds limit the sensitivity and accuracy of PGNAA. Since most of the prompt gamma rays from the same element are emitted in coincidence, a possible approach for further improvement is to change the traditional PGNAA measurement technique and introduce the gamma-gamma coincidence technique. It is well known that the coincidence techniques can eliminate most of the interference backgrounds and improve the signal-to-noise ratio. A new Monte Carlo code, CEARCPG has been developed at CEAR to simulate gamma-gamma coincidence spectra in PGNAA experiment. Compared to the other existing Monte Carlo code CEARPGA I and CEARPGA II, a new algorithm of sampling the prompt gamma rays produced from neutron capture reaction and neutron inelastic scattering reaction, is developed in this work. All the prompt gamma rays are taken into account by using this new algorithm. Before this work, the commonly used method is to interpolate the prompt gamma rays from the pre-calculated gamma-ray table. This technique works fine for the single spectrum. However it limits the capability to simulate the coincidence spectrum. The new algorithm samples the prompt gamma rays from the nucleus excitation scheme. The primary nuclear data library used to sample the prompt gamma rays comes from ENSDF library. Three cases are simulated and the simulated results are benchmarked with experiments. The first case is the prototype for ETI PGNAA application. This case is designed to check the capability of CEARCPG for single spectrum simulation. The second

  3. A sensitive continuum analysis method for gamma ray spectra

    NASA Technical Reports Server (NTRS)

    Thakur, Alakh N.; Arnold, James R.

    1993-01-01

    In this work we examine ways to improve the sensitivity of the analysis procedure for gamma ray spectra with respect to small differences in the continuum (Compton) spectra. The method developed is applied to analyze gamma ray spectra obtained from planetary mapping by the Mars Observer spacecraft launched in September 1992. Calculated Mars simulation spectra and actual thick target bombardment spectra have been taken as test cases. The principle of the method rests on the extraction of continuum information from Fourier transforms of the spectra. We study how a better estimate of the spectrum from larger regions of the Mars surface will improve the analysis for smaller regions with poorer statistics. Estimation of signal within the continuum is done in the frequency domain which enables efficient and sensitive discrimination of subtle differences between two spectra. The process is compared to other methods for the extraction of information from the continuum. Finally we explore briefly the possible uses of this technique in other applications of continuum spectra.

  4. Multivariate analysis of gamma spectra to characterize used nuclear fuel

    DOE PAGES

    Coble, Jamie; Orton, Christopher; Schwantes, Jon

    2017-01-17

    The Multi-Isotope Process (MIP) Monitor provides an efficient means to monitor the process conditions in used nuclear fuel reprocessing facilities to support process verification and validation. The MIP Monitor applies multivariate analysis to gamma spectroscopy of key stages in the reprocessing stream in order to detect small changes in the gamma spectrum, which may indicate changes in process conditions. This research extends the MIP Monitor by characterizing a used fuel sample after initial dissolution according to the type of reactor of origin (pressurized or boiling water reactor; PWR and BWR, respectively), initial enrichment, burn up, and cooling time. Simulated gammamore » spectra were used in this paper to develop and test three fuel characterization algorithms. The classification and estimation models employed are based on the partial least squares regression (PLS) algorithm. A PLS discriminate analysis model was developed which perfectly classified reactor type for the three PWR and three BWR reactor designs studied. Locally weighted PLS models were fitted on-the-fly to estimate the remaining fuel characteristics. For the simulated gamma spectra considered, burn up was predicted with 0.1% root mean squared percent error (RMSPE) and both cooling time and initial enrichment with approximately 2% RMSPE. Finally, this approach to automated fuel characterization can be used to independently verify operator declarations of used fuel characteristics and to inform the MIP Monitor anomaly detection routines at later stages of the fuel reprocessing stream to improve sensitivity to changes in operational parameters that may indicate issues with operational control or malicious activities.« less

  5. Gamma Detector Response and Analysis Software - Light

    SciTech Connect

    Mitchell, Dean J.

    2004-06-14

    GADRAS is used to analyze gamma-ray spectra, which may be augmented by neutron count rate information. The fundamental capabilities of GADRAS are imparted by physics-based detector response functions for a variety of gamma ray and neufron detectors. The software has provisions for characterizing detector response parameters so that specta can be computed accurately over the range 30keV key to II MeV. Associated neutron detector count rates can also be computed for characterized detectors. GADRAS incorporates a variety of analysis algorithms that utilize the computed spectra. The full version of GADRAS incorporates support for computation of radiation leakages from complex source models, but this capability is not supported by GADRAS-LT. GADRAS has been and will continue to be disseminated free of charge to government agencies and National Laboratories as OUO software. GADRAS-LT is a limited software version that was prepared for exclusive use of our Technology Transfer parnter Thermo Electron (TE). TE will use the software to characterize and test radiation detectors that are fabricated under the terms of our partnership. The development of these sensors has been defined as a National Security priority by our sponsor, NNSA/NA-20, by DHS/S&T, and by SNL president Paul Robinson. Although GADRAS-LT is OUO, features that are not essential to the detector development have been removed. TE will not be licensed to commercialize GADRAS-LT or to distribute it to third parties.

  6. The Spectrum of Isotropic Diffuse Gamma-Ray Emission Between 100 Mev and 820 Gev

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Brandt, T. J.; Hays, E.; Perkins, J. S.

    2014-01-01

    The gamma-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse gamma-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission, and a longer data accumulation of 50 months, allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature, and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 plus or minus 0.02 and a break energy of (279 plus or minus 52) GeV using our baseline diffuse Galactic emission model. The total intensity attributed to the IGRB is (7.2 plus or minus 0.6) x 10(exp -6) cm(exp -2) s(exp -1) sr(exp -1) above 100 MeV, with an additional +15%/-30% systematic uncertainty due to the Galactic diffuse foregrounds.

  7. Angular spectrum analysis in heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Llanes-Estrada, Felipe J.; Muñoz Martínez, Jose L.

    2017-01-01

    Heavy Ion Collisions serve to study some features of early-universe cosmology. In this contribution we adapt data analysis frequently used to understand the Cosmic Microwave Background anisotropies (such as the Mollweide projection and the angular power spectrum) to heavy ion collisions at the LHC. We examine a few publicly available events of the ALICE collaboration under this light. Because the ALICE time projection chamber has limited coverage in rapidity and some blind angles in the transverse plane, the angular spectrum seems very influenced by the detector's acceptance.

  8. Fermi Large Area Telescope detection of a break in the gamma-ray spectrum of the supernova remnant Cassiopeia A [Fermi-LAT detection of a break in the gamma-ray spectrum of the supernova remnant Cassiopeia A

    SciTech Connect

    Yuan, Yajie; Funk, Stefan; Jóhannesson, Gülauger; Lande, Joshua; Tibaldo, Luigi; Uchiyama, Yasunobu

    2013-12-02

    Here, we report on observations of the supernova remnant Cassiopeia A in the energy range from 100 MeV to 100 GeV using 44 months of observations from the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope. We perform a detailed spectral analysis of this source and report on a low-energy break in the spectrum at $1.72^{+1.35}_{-0.89}$ GeV. By comparing the results with models for the gamma-ray emission, we find that hadronic emission is preferred for the GeV energy range.

  9. Development of low level 226Ra analysis for live fish using gamma-ray spectrometry

    NASA Astrophysics Data System (ADS)

    Chandani, Z.; Prestwich, W. V.; Byun, S. H.

    2017-06-01

    A low level 226Ra analysis method for live fish was developed using a 4π NaI(Tl) gamma-ray spectrometer. In order to find out the best algorithm for accomplishing the lowest detection limit, the gamma-ray spectrum from a 226Ra point was collected and nine different methods were attempted for spectral analysis. The lowest detection limit of 0.99 Bq for an hour counting occurred when the spectrum was integrated in the energy region of 50-2520 keV. To extend 226Ra analysis to live fish, a Monte Carlo simulation model with a cylindrical fish in a water container was built using the MCNP code. From simulation results, the spatial distribution of the efficiency and the efficiency correction factor for the live fish model were determined. The MCNP model will be able to be conveniently modified when a different fish or container geometry is employed as fish grow up in real experiments.

  10. A HIGH SIGNAL-TO-NOISE RATIO COMPOSITE SPECTRUM OF GAMMA-RAY BURST AFTERGLOWS

    SciTech Connect

    Christensen, L.; Fynbo, J. P. U.; Prochaska, J. X.; Jakobsson, P.

    2011-02-01

    We present a composite spectrum of 60 long duration gamma-ray burst (GRB) afterglows with redshifts in the range 0.35 < z < 6.7 observed with low-resolution optical spectra. The composite spectrum covers the wavelength range 700-6600 A in the rest frame and has a mean signal-to-noise ratio of 150 per 1 A pixel and reaches a maximum of {approx}300 in the range 2500-3500 A. Equivalent widths are measured from metal absorption lines from the Ly{alpha} line to {approx}5200 A, and associated metal and hydrogen lines are identified between the Lyman break and Ly{alpha} line. The average transmission within the Lyman forest is consistent with that found along quasar lines of sight. We find a temporal variation in fine-structure lines when dividing the sample into bursts observed within 2 hr from their trigger and those observed later. Other lines in the predominantly neutral gas show variations too, but this is most likely a random effect caused by weighting of individual strong absorption lines and which mimics a temporal variation. Bursts characterized with high- or low-prompt GRB energy release produce afterglows with similar absorption line strengths, and likewise for bursts with bright or faint optical afterglows. Bursts defined as dark from their optical to X-ray spectral index have stronger absorption lines relative to the optically bright bursts. The composite spectrum has strong Ca II and Mg II absorption lines as commonly found in dusty galaxies, however, we find no evidence for dust or a significant molecular content based on the non-detection of diffuse interstellar bands. Compared to starburst galaxy spectra, the GRB composite has much stronger fine-structure lines, while metal absorption lines are weaker.

  11. Gamma Detector Response and Analysis Software (GADRAS) v. 16.0

    SciTech Connect

    Mitchell, Dean; & Mattingly, John

    2009-12-24

    GADRAS is a general purpose application for the modeling and analysis of radiation detector responses, primarily gamma spectroscopic instruments and neutron detectors based on proportional counters. It employs radiation source and detector response models to predict the response of user-defined detectors to user-defined sources. It implements methods to identify radiation sources from their measured signatures, primarily the measured gamma spectrum and neutron count rate. Radiation source emissions are calculated using analytical and numerical radiation transport models. Detector responses are calculated using point models of the detector material, dimensions, collimation, and scattering environment. Analytical methods are implemented using linear and nonlinear regression techniques.

  12. Energy spectrum and flux of 3- to 20-Mev neutrons and 1- to 10-Mev gamma rays in the atmosphere

    NASA Technical Reports Server (NTRS)

    Klumpar, D. M.; Lockwood, J. A.; Saint Onge, R. N.; Friling, L. A.

    1973-01-01

    An experiment is described which was designed to measure the neutron and gamma ray energy spectrums and fluxes in the energy intervals 3 to 20 MeV and 1 to 10 MeV, respectively. In addition, from the 3 to 20-MeV proton recoil spectrums it is possible to infer the shape of the neutron energy spectrum from 20 to 50 MeV. The detecting system utilized a separate charged particle rejection scheme and a two-parameter display system for the output from the pulse shape discrimination which separated gamma rays from neutrons (n). Two long-duration flights were made with this detector in 1970 at Palestine, Tex. (P sub c = 4.6 Gv) and at Ft. Churchill, Canada (P sub c = 0.3 Gv).

  13. Gamma-ray spectral analysis algorithm library

    SciTech Connect

    Egger, A. E.

    2013-05-06

    The routines of the Gauss Algorithms library are used to implement special purpose products that need to analyze gamma-ray spectra from Ge semiconductor detectors as a part of their function. These routines provide the ability to calibrate energy, calibrate peakwidth, search for peaks, search for regions, and fit the spectral data in a given region to locate gamma rays.

  14. [Laser Raman spectrum analysis of carbendazim pesticide].

    PubMed

    Wang, Xiao-bin; Wu, Rui-mei; Liu, Mu-hua; Zhang, Lu-ling; Lin, Lei; Yan, Lin-yuan

    2014-06-01

    Raman signal of solid and liquid carbendazim pesticide was collected by laser Raman spectrometer. The acquired Raman spectrum signal of solid carbendazim was preprocessed by wavelet analysis method, and the optimal combination of wavelet denoising parameter was selected through mixed orthogonal test. The results showed that the best effect was got with signal to noise ratio (SNR) being 62.483 when db2 wavelet function was used, decomposition level was 2, the threshold option scheme was 'rigisure' and reset mode was 'sln'. According to the vibration mode of different functional groups, the de-noised Raman bands could be divided into 3 areas: 1 400-2 000, 700-1 400 and 200-700 cm(-1). And the de-noised Raman bands were assigned with and analyzed. The characteristic vibrational modes were gained in different ranges of wavenumbers. Strong Raman signals were observed in the Raman spectrum at 619, 725, 964, 1 022, 1 265, 1 274 and 1 478 cm(-1), respectively. These characteristic vibrational modes are characteristic Raman peaks of solid carbendazim pesticide. Find characteristic Raman peaks at 629, 727, 1 001, 1 219, 1 258 and 1 365 cm(-1) in Raman spectrum signal of liquid carbendazim. These characteristic peaks were basically tallies with the solid carbendazim. The results can provide basis for the rapid screening of pesticide residue in food and agricultural products based on Raman spectrum.

  15. GRABGAM Analysis of Ultra-Low-Level HPGe Gamma Spectra

    SciTech Connect

    Winn, W.G.

    1999-07-28

    The GRABGAM code has been used successfully for ultra-low level HPGe gamma spectrometry analysis since its development in 1985 at Savannah River Technology Center (SRTC). Although numerous gamma analysis codes existed at that time, reviews of institutional and commercial codes indicated that none addressed all features that were desired by SRTC. Furthermore, it was recognized that development of an in-house code would better facilitate future evolution of the code to address SRTC needs based on experience with low-level spectra. GRABGAM derives its name from Gamma Ray Analysis BASIC Generated At MCA/PC.

  16. A US coordination Facility for the Spectrum-X-Gamma Observatory

    NASA Technical Reports Server (NTRS)

    Forman, W.; West, Donald (Technical Monitor)

    2001-01-01

    We have completed our efforts in support of the Spectrum X Gamma mission under a NASA grant. These activities have included direct support to the mission, developing unifying tools applicable to SXG and other X-ray astronomy missions, and X-ray astronomy research to maintain our understanding of the importance and relevance of SXG to the field. SXG provides: 1) Simultaneous Multiwavelength Capability; 2) Large Field of View High Resolution Imaging Spectroscopy; 3) Sensitive Polarimetry with SXRP (Stellar X-Ray Polarimeter). These capabilities will ensure the fulfillment of the following objectives: understanding the accretion dynamics and the importance of reprocessing, upscattering, and disk viscosity around black holes; studying cluster mergers; spatially resolving cluster cooling flows to detect cooling gas; detecting cool gas in cluster outskirts in absorption; mapping gas in filaments around clusters; finding the 'missing' baryons in the Universe; determining the activity history of the black hole in the Galactic Center of our own central black hole; determining pulsar beam geometry; searching for the Lense-Thirring effect in black hole sources; constraining emission mechanisms and accretion geometry in AGN.

  17. Objective Crystal Spectrometer (OXS) for the Spectrum-X-Gamma satellite

    NASA Astrophysics Data System (ADS)

    Christensen, F. E.; Byrnak, B. P.; Hornstrup, A.; Schnopper, H. W.; Shou-Hua, Z.

    1990-11-01

    The status of the Objective Crystal Spectrometer (OXS) to be flown on the Soviet Spectrum-X-Gamma satellite together with the X-ray investigation of two of the three natural crystals (LiF(220), Ge(111) and RAP(001) which are chosen as the baseline option are presented. An important result of this study is the approximately 50 percent higher resolution obtained by polishing the LiF(220) surface. The measured X-ray data has been used to determine the OXS specifications. A simulation of the performance of the OXS for the LiF(220)-case are presented. A novel design in which multilayers are coated on the LiF(220) and Ge(111) surfaces is presented. This design allows simultaneous spectroscopy in two energy bands each centered on cosmically interesting line emission regions. X-ray reflectivity measurements demonstrate that the crystal surface can be made sufficiently smooth for the application of the multilayer coating. The first X-ray reflectivity data of multilayers deposited on these surfaces are also reported.

  18. On the determination of the cosmic infrared background radiation from the high-energy spectrum of extragalactic gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Dwek, Eli; Slavin, Jonathan

    1994-01-01

    In a recent paper Stecker, De Jager, & Salamon have suggested using the observed approximately MeV to TeV spectra of extragalactic gamma-ray sources as probes of the local density of the cosmic infrared background radiation (CIBR) and have subsequently claimed a first possible measurement of the CIBR from the analysis of the gamma-ray spectrum of Mrk 421 (De Jager, Stecker, & Salamon). The CIBR from normal galaxies consists of two components: a stellar emission component (CIBRs), and a thermal dust emission component (CIBRd). Photons with energies in the approximately 0.1-2 TeV range interact primarily with the CIBRs, whereas interactions with CIBRd dominate the absorption of photons in the approximately 2-100 TeV energy range. SDS 92 and DSS94 considered only the interaction of the gamma-rays with the dust emission component of the CIBR. We present here an improved analysis of the absorption of extragalactic TeV gamma rays by the CIBR, taking the dual nature of its origin into account. Applying the analysis to the observed gamma-ray spectrum of Mrk 421, a BL Lac object at z = 0.031, we find agreement with DSS94 tentative evidence for absorption by the CINRs. Our analysis therefore limits the detection of the CIBR to the approximately 15-40 micron wavelength regime which, considering the uncertainties in the highest energy (greater than 4 TeV) data and ion the possibility of absorption inside the source, many turn out to be an upper limit on its energy density. At shorter wavelengths (lambda approximately = 1-15 microns), where the gamma-ray interactions are dominated by the CIBRs, our analysis definitely yields only an upper limit on the energy density of the CIBR. In contrast, DSS94 have claimed a possible first measurement of the CIBR over the entire 1-120 micron wavelength region. The upper limit on the CIBRs and tentative detection of the CIBRd are consistent with normal galaxies contributing most of the energy to the CIBR, and constrain the contribution of

  19. On the determination of the cosmic infrared background radiation from the high-energy spectrum of extragalactic gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Dwek, Eli; Slavin, Jonathan

    1994-01-01

    In a recent paper Stecker, De Jager, & Salamon have suggested using the observed approximately MeV to TeV spectra of extragalactic gamma-ray sources as probes of the local density of the cosmic infrared background radiation (CIBR) and have subsequently claimed a first possible measurement of the CIBR from the analysis of the gamma-ray spectrum of Mrk 421 (De Jager, Stecker, & Salamon). The CIBR from normal galaxies consists of two components: a stellar emission component (CIBRs), and a thermal dust emission component (CIBRd). Photons with energies in the approximately 0.1-2 TeV range interact primarily with the CIBRs, whereas interactions with CIBRd dominate the absorption of photons in the approximately 2-100 TeV energy range. SDS 92 and DSS94 considered only the interaction of the gamma-rays with the dust emission component of the CIBR. We present here an improved analysis of the absorption of extragalactic TeV gamma rays by the CIBR, taking the dual nature of its origin into account. Applying the analysis to the observed gamma-ray spectrum of Mrk 421, a BL Lac object at z = 0.031, we find agreement with DSS94 tentative evidence for absorption by the CINRs. Our analysis therefore limits the detection of the CIBR to the approximately 15-40 micron wavelength regime which, considering the uncertainties in the highest energy (greater than 4 TeV) data and ion the possibility of absorption inside the source, many turn out to be an upper limit on its energy density. At shorter wavelengths (lambda approximately = 1-15 microns), where the gamma-ray interactions are dominated by the CIBRs, our analysis definitely yields only an upper limit on the energy density of the CIBR. In contrast, DSS94 have claimed a possible first measurement of the CIBR over the entire 1-120 micron wavelength region. The upper limit on the CIBRs and tentative detection of the CIBRd are consistent with normal galaxies contributing most of the energy to the CIBR, and constrain the contribution of

  20. Fermi-LAT Detection of an Unusual Hard Spectrum and Enhanced Gamma-ray Emission from the FSRQ PKS B1035-281

    NASA Astrophysics Data System (ADS)

    Carpenter, Bryce; Ojha, Roopesh

    2016-02-01

    The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope has observed increasing gamma-ray flux and an unusually hard spectrum from a source positionally consistent with the flat spectrum radio quasar PKS B1035-281 (also known as 3FGL J1037.5-2821, Acero et al. 2015, ApJS, 218, 23) with radio coordinates R.A.: 159.4269058 deg, Dec: -28.3844750 deg (J2000, Beasley et al. 2002, ApJS, 141, 13) at redshift z=1.066 (Shaw et al. 2012, ApJ, 748, 49). Preliminary analysis indicates that on 24 February 2016 this source was in a high-flux state, with a daily averaged gamma-ray flux (E > 100MeV) of (0.7+/-0.1) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only) corresponding to a flux increase of a factor of about 30 over its four-year average flux (3FGL J1037.5-2821).

  1. Analysis of the 237Np-233Pa photon spectrum using the full response function method.

    PubMed

    Shchukin, G; Iakovlev, K; Morel, J

    2004-01-01

    A study has been made of X- and gamma-ray emission from 237Np in equilibrium with 233Pa using the full response function method. This analysis process is characterised by photon spectrometry in which the entire spectrum is modelled in a pseudo-empirical way by means of elementary functions describing the total absorption and escape peaks, the Compton diffusion internal and external to the detector and the peaks resulting from detection of internal conversion electrons. This method has been applied to determine the L X-, K X- and gamma-rays emission probabilities in 237Np and 233Pa decay studies.

  2. Radiative-neutron-capture gamma-ray analysis by a linear combination technique

    USGS Publications Warehouse

    Tanner, A.B.; Bhargava, R.C.; Senftle, F.E.; Brinkerhoff, J.M.

    1972-01-01

    The linear combination technique, when applied to a gamma-ray spectrum, gives a single number indicative of the extent to which the spectral lines of a sought element are present in a complex spectrum. Spectra are taken of the sought element and of various other substances whose spectra interfere with that of the sought element. A weighting function is then computed for application to spectra of unknown materials. The technique was used to determine calcium by radiative-neutron-capture gamma-ray analysis in the presence of interfering elements, notably titanium, and the results were compared with those for two popular methods of peak area integration. Although linearity of response was similar for the methods, the linear combination technique was much better at rejecting interferences. For analyses involving mixtures of unknown composition the technique consequently offers improved sensitivity. ?? 1972.

  3. MOXE - An X-ray all-sky monitor for the Soviet Spectrum-X-Gamma mission

    NASA Technical Reports Server (NTRS)

    Priedhorsky, W.; Fenimore, E. E.; Moss, C. E.; Kelley, R. L.; Holt, S. S.

    1989-01-01

    A Monitoring X-Ray Equipment (MOXE) is being developed for the Soviet Spectrum-X-Gamma Mission. MOXE is an X-ray all-sky monitor based on array of pinhole cameras, to be provided via a collaboration between Goddard Space Flight Center and Los Alamos National Laboratory. The objectives are to alert other observers on Spectrum-X-Gamma and other platforms of interesting transient activity, and to synoptically monitor the X-ray sky and study long-term changes in X-ray binaries. MOXE will be sensitive to source as faint as 2 milliCrab (5 sigma) in 1 day, and cover the 2 to 20 KeV band.

  4. Effects of p-wave annihilation on the angular power spectrum of extragalactic gamma-rays from dark matter annihilation

    NASA Astrophysics Data System (ADS)

    Campbell, Sheldon; Dutta, Bhaskar

    2011-10-01

    We present a formalism for estimating the angular power spectrum of extragalactic gamma-rays produced by dark matter annihilating with any general velocity-dependent cross section. The relevant density and velocity distribution of dark matter is modeled as an ensemble of smooth, universal, rigid, disjoint, spherical halos with distribution and universal properties constrained by simulation data. We apply this formalism to theories of dark matter with p-wave annihilation, for which the relative-velocity-weighted annihilation cross section is σv=a+bv2. We determine that this significantly increases the gamma-ray power if b/a≳106. The effect of p-wave annihilation on the angular power spectrum is very similar for the sample of particle physics models we explored, suggesting that the important effect for a given b/a is largely determined by the cosmic dark matter distribution. If the dark matter relic from strong p-wave theories is thermally produced, the intensities of annihilation gamma-rays are strongly p-wave suppressed, making them difficult to observe. If an angular power spectrum consistent with a strong p wave were to be observed, it would likely indicate nonthermal production of dark matter in the early Universe.

  5. The design of a source to simulate the gamma-ray spectrum emitted by a radioisotope thermoelectric generator

    NASA Technical Reports Server (NTRS)

    Reier, M.

    1972-01-01

    A simulated source was designed to duplicate the gamma spectrum of a uniform cylindrical 2200-watt Pu02 radioisotope thermoelectric generator containing 81% Pu-238 and 1.2 ppm Pu-236. Gamma rays from the decay of Pu-238, Am-241, Pu-239, and the 0-18(alpha,n)Ne-21 reaction were catalogued in broad energy groups. Two 46- and one 22-mc Th-228 sources provided simulation at various times in the life of the fuel capsule up to 18 years, which covers the time span of an outer planet mission. Emission from Th-228 represents the overwhelming contribution of the gamma spectrum after the first few years. The sources, in the form of 13-inch rods, were placed in a concentric hole in a cylinder of depleted uranium, which provided shielding equivalent to the self-shielding of the fuel capsule. The thickness of the U-238 cylinder (0.55cm) was determined by Monte Carlo calculations to insure that the spectrum emerging from the simulated source matched that of the fuel capsule.

  6. Elemental PGNAA analysis using gamma-gamma coincidence counting with the library least-squares approach

    NASA Astrophysics Data System (ADS)

    Metwally, Walid A.; Gardner, Robin P.; Mayo, Charles W.

    2004-01-01

    An accurate method for determining elemental analysis using gamma-gamma coincidence counting is presented. To demonstrate the feasibility of this method for PGNAA, a system of three radioisotopes (Na-24, Co-60 and Cs-134) that emit coincident gamma rays was used. Two HPGe detectors were connected to a system that allowed both singles and coincidences to be collected simultaneously. A known mixture of the three radioisotopes was used and data was deliberately collected at relatively high counting rates to determine the effect of pulse pile-up distortion. The results obtained, with the library least-squares analysis, of both the normal and coincidence counting are presented and compared to the known amounts. The coincidence results are shown to give much better accuracy. It appears that in addition to the expected advantage of reduced background, the coincidence approach is considerably more resistant to pulse pile-up distortion.

  7. Perceptual Integration Deficits in Autism Spectrum Disorders Are Associated with Reduced Interhemispheric Gamma-Band Coherence.

    PubMed

    Peiker, Ina; David, Nicole; Schneider, Till R; Nolte, Guido; Schöttle, Daniel; Engel, Andreas K

    2015-12-16

    The integration of visual details into a holistic percept is essential for object recognition. This integration has been reported as a key deficit in patients with autism spectrum disorders (ASDs). The weak central coherence account posits an altered disposition to integrate features into a coherent whole in ASD. Here, we test the hypothesis that such weak perceptual coherence may be reflected in weak neural coherence across different cortical sites. We recorded magnetoencephalography from 20 adult human participants with ASD and 20 matched controls, who performed a slit-viewing paradigm, in which objects gradually passed behind a vertical or horizontal slit so that only fragments of the object were visible at any given moment. Object recognition thus required perceptual integration over time and, in case of the horizontal slit, also across visual hemifields. ASD participants were selectively impaired in the horizontal slit condition, indicating specific difficulties in long-range synchronization between the hemispheres. Specifically, the ASD group failed to show condition-related enhancement of imaginary coherence between the posterior superior temporal sulci in both hemispheres during horizontal slit-viewing in contrast to controls. Moreover, local synchronization reflected in occipitocerebellar beta-band power was selectively reduced for horizontal compared with vertical slit-viewing in ASD. Furthermore, we found disturbed connectivity between right posterior superior temporal sulcus and left cerebellum. Together, our results suggest that perceptual integration deficits co-occur with specific patterns of abnormal global and local synchronization in ASD. The weak central coherence account proposes a tendency of individuals with autism spectrum disorders (ASDs) to focus on details at the cost of an integrated coherent whole. Here, we provide evidence, at the behavioral and the neural level, that visual integration in object recognition is impaired in ASD, when

  8. Hard x-ray telescope concentrator for astrophysical mission Spectrum-X-Gamma

    NASA Astrophysics Data System (ADS)

    Pavlinsky, M.; Arefiev, V.; Churazov, E.; Gilfanov, M.; Grigorovich, S.; Litvin, D.; Lapshov, I.; Levin, V.; Akimov, V.; Semena, N.; Tkachenko, A.; Vikhlinin, A.; Sunyaev, R.; Ramsey, B. D.; Gubarev, M. V.; Elsner, R. F.; O'Dell, S. L.; Weisskopf, M. C.

    2007-09-01

    The hard X-ray telescope-concentrator ART-XC on board the Spectrum-X-Gamma X-ray astrophysical observatory (launching in 2011) is one of the main instruments of the mission. The instrument will be used for an all-sky survey and then for pointed observations which are planned for the first four and the next three years of the Mission, respectively. ART-XC will be sensitive in the 4-30 keV energy range and will have an effective area of several hundred square centimeters at 10 keV. It will have a field of view of about ~28 arcmin, angular resolution better than 1 arcmin and will be an order of magnitude more sensitive than the current generation of collimated instruments and coded mask telescopes in the survey mode and a two or three orders of magnitude more sensitive in the pointing mode. With its high sensitivity in the hard X-ray band and good imaging capabilities, ART-XC will extend the operating energy range of the observatory (complementing the capabilities of the primary science instrument eROSITA), thus significantly enhancing the mission both in the all-sky survey over the energy band 4-10 keV and, especially, in pointed observations over the energy band 4-30 keV. During the 4-year survey, this ART-XC would detect more than ~10 4 sources over 4-10 keV. For a 10 5 second pointed observation, the telescope will provide better than 10 microCrab sensitivity in the 4-20 keV energy range.

  9. Application of spectrum shifting methodology to restore NaI(Tl)-recorded gamma spectra, shifted due to temperature variations in the environment.

    PubMed

    Mitra, Pratip; Roy, Arup Singha; Verma, Amit K; Pant, Amar D; Prakasha, M S; Anilkumar, S; Kumar, A Vinod

    2016-01-01

    A method has been standardized for restoring a shifted differential pulse height spectrum from a scintillator based gamma ray spectrometer recorded at measurement temperature, to the position of a desired spectrum, recorded at a reference temperature. The method is based on the assumption that the spectrum obtained at measurement temperature represents the same statistical distribution as that at reference temperature but with different energy scales. A computer program has been developed for calculation of the transformation between the energy scales and for the restoration of the shifted spectrum. The method developed has been successfully applied for the restoration of gamma spectra measured at different temperatures.

  10. MOOG: LTE line analysis and spectrum synthesis

    NASA Astrophysics Data System (ADS)

    Sneden, Chris; Bean, Jacob; Ivans, Inese; Lucatello, Sara; Sobeck, Jennifer

    2012-02-01

    MOOG performs a variety of LTE line analysis and spectrum synthesis tasks. The typical use of MOOG is to assist in the determination of the chemical composition of a star. The basic equations of LTE stellar line analysis are followed. The coding is in various subroutines that are called from a few driver routines; these routines are written in standard FORTRAN. The standard MOOG version has been developed on unix, linux and macintosh computers. One of the chief assets of MOOG is its ability to do on-line graphics. The plotting commands are given within the FORTRAN code. MOOG uses the graphics package SM, chosen for its ease of implementation in FORTRAN codes. Plotting calls are concentrated in just a few routines, and it should be possible for users of other graphics packages to substitute other appropriate FORTRAN commands.

  11. Total Gamma Count Rate Analysis Method for Nondestructive Assay Characterization

    SciTech Connect

    Cecilia R. Hoffman; Yale D. Harker

    2006-03-01

    A new approach to nondestructively characterize waste for disposal, based on total gamma response, has been developed at the Idaho Cleanup Project by CH2M-WG Idaho, LLC and Idaho State University, and is called the total gamma count rate analysis method. The total gamma count rate analysis method measures gamma interactions that produce energetic electrons or positrons in a detector. Based on previous experience with waste assays, the radionuclide content of the waste container is then determined. This approach potentially can yield minimum detection limits of less than 10 nCi/g. The importance of this method is twofold. First, determination of transuranic activity can be made for waste containers that are below the traditional minimum detection limits. Second, waste above 10 nCi/g and below 100 nCi/g can be identified, and a potential path for disposal resolved.

  12. A mass spectrometric analysis of {gamma}-GPS films

    SciTech Connect

    Dillingham, R.G.; Boerio, F.J.; Bertelsen, C.; Savina, M.R.; Lykke, K.R.; Calaway, W.F.

    1996-06-01

    {gamma}-glycidoxypropyltrimethoxysilane ({gamma}-GPS) is used for pre-treatment of grit-blasted aluminum before adhesive bonding. This paper discusses analysis of non-reflective grit-blasted surfaces using mass spectrometry of species that were either sputtered off using an ion beam or thermally desorbed as neutrals using a pulsed laser and then post-ionized using a secondary laser. Results show that fragmentation is excessive and structural information is difficult to obtain from the spectra.

  13. Singular Spectrum Analysis in Astrometry and Geodynamics

    NASA Astrophysics Data System (ADS)

    Vityazev, V. V.; Miller, N. O.; Prudnikova, E. Ja.

    2010-10-01

    The paper presents the possibilities of the Singular Spectrum Analyses on the examples of its application to several astrometric and geodynamic time series. The comparisons of results obtained by other often used methods (Fourier transform, Wavelet Transform, different filter methods) are given. The Singular Spectrum Analyses method was used for the investigation of the Chandler wobble (CW), which was extracted from the IERS Pole coordinates and latitude variations at Pulkovo. The CW amplitude and phase variations were examined by means of the Hilbert transform. The main conclusion which can be made from this study is: we have found two epochs of deep CW amplitude decreases near 1850 and 2005, which are also accompanied by a large phase jump, similar to well known event in 1920s. The investigation of first latitude observations at Pulkovo (1840-1855) was executed with the aim to gain and analyse the sum of Chandler and annual components from very small quantity of very noisy observations. The SSA is applied for investigation of the zenith troposphere delay time-series derived from observations of several VLBI stations. Combined IVS time-series of the zenith wet and total troposphere delays obtained in IGG were used for analysis. For all stations under consideration the non-linear trends and the seasonal components with annual and semiannual periods were found. Some interesting peculiarities were found to be individual for every stations. Comparison of the trends with meteorological parameters is also presented.

  14. Prompt Gamma Ray Analysis of Soil Samples

    SciTech Connect

    Naqvi, A.A.; Khiari, F.Z.; Haseeb, S.M.A.; Hussein, Tanvir; Khateeb-ur-Rehman; Isab, A.H.

    2015-07-01

    Neutron moderation effects were measured in bulk soil samples through prompt gamma ray measurements from water and benzene contaminated soil samples using 14 MeV neutron inelastic scattering. The prompt gamma rays were measured using a cylindrical 76 mm x 76 mm (diameter x height) LaBr{sub 3}:Ce detector. Since neutron moderation effects strongly depend upon hydrogen concentration of the sample, for comparison purposes, moderation effects were studied from samples containing different hydrogen concentrations. The soil samples with different hydrogen concentration were prepared by mixing soil with water as well as benzene in different weight proportions. Then, the effects of increasing water and benzene concentrations on the yields of hydrogen, carbon and silicon prompt gamma rays were measured. Moderation effects are more pronounced in soil samples mixed with water as compared to those from soil samples mixed with benzene. This is due to the fact that benzene contaminated soil samples have about 30% less hydrogen concentration by weight than the water contaminated soil samples. Results of the study will be presented. (authors)

  15. The stealth spectrum analysis (SSA) of the electronic systems

    NASA Astrophysics Data System (ADS)

    Wang, Dequan

    Stealth spectrum analysis is discussed for assessing total system stability in aircraft communications and navigation equipment by evaluating the stealth circuit. The general frequency response and convolution are calculated for the entire frequency spectrum in both the frequency and time domains. The general energy-density spectrum and the general equivalent noise bandwidth can be computed to analyze problems with stealth technologies.

  16. Determining the isotopic concentration of uranium from vector representation of the gamma spectrum

    NASA Astrophysics Data System (ADS)

    White, Tristan Glover

    Gamma emissions from Uranium-235 in a source of interest were compared to gamma emissions from Protactinium-234m (which is in equilibrium with Uranium-238) in order to determine the isotopic composition of the source. The 144 keV gamma ray from U-235 was compared with 1001 keV gamma ray from Pa-234m. Two analytical methods were compared: the relative activity method and the vector representation method. The relative activity method is similar to the (standard) relative intensity method, but accounts for more variables. Calculations were performed using both methods in order to evaluate precision and accuracy. Relative activity compares the number of counts under one gamma-ray peak from a reference source to the number of counts under another peak from an unknown source. This method is sensitive to systematic errors in the efficiency calibration of the detector when two different peaks with different energies are used. Vector representation compares the count ratio of two gamma-ray peaks from one source to the count ratio of the same two gamma-ray peaks from another source. Vector representation was found to be practical for analyzing depleted uranium, but not highly enriched uranium (HEU), due to different branching ratios and detector efficiency.

  17. Study of the very high energy gamma-ray spectrum from the Galactic Center and future prospects

    NASA Astrophysics Data System (ADS)

    Belikov, Alexander V.; Moulin, Emmanuel; Silk, Joseph

    2016-11-01

    Ground-based gamma-ray observations of the Galactic Center region have revealed a high energy gamma-ray source spatially coincident with the gravitational centroid of our Galaxy. The pointlike emission detected by HESS exhibits an energy cutoff at about 10 TeV. We identify the parameters of the best fit of the exponential and the superexponential cutoff models to the spectrum of the pointlike source and find that the superexponential one provides a similar quality of fit to the spectrum of the pointlike source as the best-fit exponential cutoff model, while a dark matter interpretation does not provide as good a fit in the whole energy range of the signal. Based on the magnitude of the flux we derive constraints in the plane of the slope of the density profile γ and the critical radius, below which the density is assumed to be constant, rc. Motivated by recent results on the spectrum and morphology from HESS and by the possible observation of a superexponential cutoff, we forecast the observations of superexponential versus exponential cutoffs by the upcoming Cherenkov Telescope Array. We derive a formula for J -factor in the small-angle approximation and propose approximate morphological constraints on the central source.

  18. An optical spectrum of the afterglow of a gamma-ray burst at a redshift of z = 6.295.

    PubMed

    Kawai, N; Kosugi, G; Aoki, K; Yamada, T; Totani, T; Ohta, K; Iye, M; Hattori, T; Aoki, W; Furusawa, H; Hurley, K; Kawabata, K S; Kobayashi, N; Komiyama, Y; Mizumoto, Y; Nomoto, K; Noumaru, J; Ogasawara, R; Sato, R; Sekiguchi, K; Shirasaki, Y; Suzuki, M; Takata, T; Tamagawa, T; Terada, H; Watanabe, J; Yatsu, Y; Yoshida, A

    2006-03-09

    The prompt gamma-ray emission from gamma-ray bursts (GRBs) should be detectable out to distances of z > 10 (ref. 1), and should therefore provide an excellent probe of the evolution of cosmic star formation, reionization of the intergalactic medium, and the metal enrichment history of the Universe. Hitherto, the highest measured redshift for a GRB has been z = 4.50 (ref. 5). Here we report the optical spectrum of the afterglow of GRB 050904 obtained 3.4 days after the burst; the spectrum shows a clear continuum at the long-wavelength end of the spectrum with a sharp cut-off at around 9,000 A due to Lyman alpha absorption at z approximately 6.3 (with a damping wing). A system of absorption lines of heavy elements at z = 6.295 +/- 0.002 was also detected, yielding the precise measurement of the redshift. The Si ii fine-structure lines suggest a dense, metal-enriched environment around the progenitor of the GRB.

  19. A celestial gamma-ray foreground due to the albedo of small solar system bodies and a remote probe of the interstellar cosmic ray spectrum

    SciTech Connect

    Moskalenko, Igor V.; Porter, Troy A.; Digel, Seth W.; Michelson, Peter F.; Ormes, Jonathan F.

    2007-12-17

    We calculate the {gamma}-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the {gamma}-ray albedo for the Main Belt and Kuiper Belt strongly depends on the small-body mass spectrum of each system and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). The orbits of the Main Belt asteroids and KBOs are distributed near the ecliptic, which passes through the Galactic center and high Galactic latitudes. If detected, the {gamma}-ray emission by the Main Belt and Kuiper Belt has to be taken into account when analyzing weak {gamma}-ray sources close to the ecliptic, especially near the Galactic center and for signals at high Galactic latitudes, such as the extragalactic {gamma}-ray emission. Additionally, it can be used to probe the spectrum of CR nuclei at close-to-interstellar conditions, and the mass spectrum of small bodies in the Main Belt and Kuiper Belt. The asteroid albedo spectrum also exhibits a 511 keV line due to secondary positrons annihilating in the rock. This may be an important and previously unrecognized celestial foreground for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observations of the Galactic 511 keV line emission including the direction of the Galactic center.

  20. The optimization of gamma spectra processing in prompt gamma neutron activation analysis (PGNAA)

    NASA Astrophysics Data System (ADS)

    Pinault, Jean-Louis; Solis, Jose

    2009-04-01

    The uncertainty of the elemental analysis is one of the major factors governing the utility of on-line Prompt Gamma Neutron Activation Analysis (PGNAA) in the blending and sorting of bulk materials. In this paper, a general method applicable to Gamma spectra processing is presented and applied to PGNAA in mineral industry. Based on the Fourier transform of spectra and their de-correlation in the Fourier space (the improvement of the conditioning of the correlation matrix), processing of overlapping of characteristic peaks minimizes the propagation of random errors, which optimizes the accuracy and decreases the detection limits of elemental analyses. In comparison with classical methods based on the linear combinations of relevant regions of spectra the improvement may be considerable, especially when several elements are interfering. The method is applied to four case stories covering both borehole logging and on-line analysis on conveyor belt of raw materials.

  1. On the high energy cut-off in the gamma-ray spectrum from Cygnus X-3

    NASA Astrophysics Data System (ADS)

    Stephens, S. A.; Verma, R. P.

    The effect of magnetic pair production on the high energy gamma-rays from Cygnus X-3 is examined, while traversing the field associated with the radio emitting region of this source. It is shown that such a process would result in a sharp steepening of the gamma-ray spectrum beyond about 10 to the 15th eV. Using the observed spectral steepening, a field strength of 0.7 gauss in the region about 10 to the 14th cms is derived, where most of the observed radio emission takes place. The observed light curve shows only one significant peak at a phase of about 0.2 from the X-ray minimum. This could result from the magnetic bending of the charged particles from the pulsar before interacting with the enshrouded matter. It is predicted that the relative contribution of steady flux would increase beyond 10 to the 16th eV.

  2. Gamma bang time analysis at OMEGA.

    PubMed

    McEvoy, A M; Herrmann, H W; Horsfield, C J; Young, C S; Miller, E K; Mack, J M; Kim, Y; Stoeffl, W; Rubery, M; Evans, S; Sedillo, T; Ali, Z A

    2010-10-01

    Absolute bang time measurements with the gas Cherenkov detector (GCD) and gamma reaction history (GRH) diagnostic have been performed to high precision at the OMEGA laser facility at the University of Rochester with bang time values for the two diagnostics agreeing to within 5 ps on average. X-ray timing measurements of laser-target coupling were used to calibrate a facility-generated laser timing fiducial with rms spreads in the measured coupling times of 9 ps for both GCD and GRH. Increased fusion yields at the National Ignition Facility (NIF) will allow for improved measurement precision with the GRH easily exceeding NIF system design requirements.

  3. Gamma bang time analysis at OMEGAa)

    NASA Astrophysics Data System (ADS)

    McEvoy, A. M.; Herrmann, H. W.; Horsfield, C. J.; Young, C. S.; Miller, E. K.; Mack, J. M.; Kim, Y.; Stoeffl, W.; Rubery, M.; Evans, S.; Sedillo, T.; Ali, Z. A.

    2010-10-01

    Absolute bang time measurements with the gas Cherenkov detector (GCD) and gamma reaction history (GRH) diagnostic have been performed to high precision at the OMEGA laser facility at the University of Rochester with bang time values for the two diagnostics agreeing to within 5 ps on average. X-ray timing measurements of laser-target coupling were used to calibrate a facility-generated laser timing fiducial with rms spreads in the measured coupling times of 9 ps for both GCD and GRH. Increased fusion yields at the National Ignition Facility (NIF) will allow for improved measurement precision with the GRH easily exceeding NIF system design requirements.

  4. Covariance Analysis of Gamma Ray Spectra

    SciTech Connect

    Trainham, R.; Tinsley, J.

    2013-01-01

    The covariance method exploits fluctuations in signals to recover information encoded in correlations which are usually lost when signal averaging occurs. In nuclear spectroscopy it can be regarded as a generalization of the coincidence technique. The method can be used to extract signal from uncorrelated noise, to separate overlapping spectral peaks, to identify escape peaks, to reconstruct spectra from Compton continua, and to generate secondary spectral fingerprints. We discuss a few statistical considerations of the covariance method and present experimental examples of its use in gamma spectroscopy.

  5. Covariance analysis of gamma ray spectra

    SciTech Connect

    Trainham, R.; Tinsley, J.

    2013-01-15

    The covariance method exploits fluctuations in signals to recover information encoded in correlations which are usually lost when signal averaging occurs. In nuclear spectroscopy it can be regarded as a generalization of the coincidence technique. The method can be used to extract signal from uncorrelated noise, to separate overlapping spectral peaks, to identify escape peaks, to reconstruct spectra from Compton continua, and to generate secondary spectral fingerprints. We discuss a few statistical considerations of the covariance method and present experimental examples of its use in gamma spectroscopy.

  6. On the assignment of the room temperature ESR spectrum of gamma irradiated poly(ethylene glycol dimethacrylate)

    NASA Astrophysics Data System (ADS)

    Brown, L.; Carswell-Pomerantz, T. G.; Hill, D. J. T.; Pomery, P. J.

    1996-11-01

    The ESR spectrum of poly(ethylene glycol dimethacrylate) observed at room temperature following gamma radiolysis is characterized by an eleven-line spectrum. Some authors have assigned the outer lines in this spectrum to the presence of formyl radicals which have been stabilized at the prevailing temperature by the cross linked network. In this paper we re-evaluate this assignment and show that a more likely explanation of the spectrum is that there is that there are three conformations of the propagating radicals present, corresponding to the three possible rotational conformers which can be formed about the β-methylene group. It is suggested that the third conformer, which is not found for poly(methyl methacrylate) and most other methacrylate polymers, is stabilized by the cross linked structure of this polymer. A similar explanation is suggested as an explanation for the eleven-line ESR spectrum observed for poly(methacrylic acid) following irradiation at room temperature, where the stabilization is suggested to occur due to hydrogen bond through the carboxyl groups.

  7. Passive Gamma Analysis of the Boiling-Water-Reactor Assemblies

    SciTech Connect

    Vo, Duc Ta; Favalli, Andrea

    2016-03-31

    Passive gamma analysis can be used to determine BU and CT of BWR assembly. The analysis is somewhat more complicated and less effective than similar method for PWR assemblies. From the measurements along the lengths of the BWR1 and BWR9 assemblies, there are hints that we may be able to use their information to help improve the model functions for better results.

  8. Anomaly Detection in Gamma-Ray Vehicle Spectra with Principal Components Analysis and Mahalanobis Distances

    SciTech Connect

    Tardiff, Mark F.; Runkle, Robert C.; Anderson, K. K.; Smith, L. E.

    2006-01-23

    The goal of primary radiation monitoring in support of routine screening and emergency response is to detect characteristics in vehicle radiation signatures that indicate the presence of potential threats. Two conceptual approaches to analyzing gamma-ray spectra for threat detection are isotope identification and anomaly detection. While isotope identification is the time-honored method, an emerging technique is anomaly detection that uses benign vehicle gamma ray signatures to define an expectation of the radiation signature for vehicles that do not pose a threat. Newly acquired spectra are then compared to this expectation using statistical criteria that reflect acceptable false alarm rates and probabilities of detection. The gamma-ray spectra analyzed here were collected at a U.S. land Port of Entry (POE) using a NaI-based radiation portal monitor (RPM). The raw data were analyzed to develop a benign vehicle expectation by decimating the original pulse-height channels to 35 energy bins, extracting composite variables via principal components analysis (PCA), and estimating statistically weighted distances from the mean vehicle spectrum with the mahalanobis distance (MD) metric. This paper reviews the methods used to establish the anomaly identification criteria and presents a systematic analysis of the response of the combined PCA and MD algorithm to modeled mono-energetic gamma-ray sources.

  9. Development of Mirror Modules for the ART-XC Instrument aboard the Spectrum-Roentgen-Gamma Mission

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail V.; Ramsey, Brian; O'Dell, Stephen L.; Elsner, Ronald F.; Kilaru, Kiranmayee; Atkins, Carolyn; Pavlinskiy, Mikhail N.; Tkachenko, Alexey V.; Lapshov, Igor Y.

    2013-01-01

    The Marshall Space Flight Center (MSFC) is developing x-ray mirror modules for the Astronomical Roengen Telescope- X-ray Concentrator (ART-XC) instrument on board the Spectrum-Roentgen-Gamma Mission. ART-XC will consist of seven co-aligned x-ray mirror modules with seven corresponding CdTe focal plane detectors. Each module provides an effective area of 65 sq cm at 8 keV, response out to 30 keV, and an angular resolution of 45 arcsec or better HPD. We will present a status of the ART x-ray module development at MSFC.

  10. An Analysis of Spectrum Research on Teaching

    ERIC Educational Resources Information Center

    Chatoupis, Constantine

    2010-01-01

    Spectrum research on teaching has been conducted since 1970s. The purpose of this study was to identify, categorize, and analyze research in this area. Fifty three Spectrum studies conducted between 1970 and 2008 were included in this study. Each paper was coded for (a) decade the study was published, (b) publication outlet/dissertation research,…

  11. Electrical spectrum analysis of operating Hydro Electric machines

    NASA Astrophysics Data System (ADS)

    Timperley, J. E.

    1981-12-01

    The electrical spectrum analysis of the operation of five pumped storage machines is discussed. It was found that machines without electrical problems produced little radio noise, although all machines produced some noise. Severe problems produced severe radio noise. If stator deterioration increases, the noise level increases. Similar machines produce similar electrical spectrum signatures. The general source of discharges can be located. A likelihood of failure can be calculated from spectrum analysis.

  12. Method and apparatus for frequency spectrum analysis

    NASA Technical Reports Server (NTRS)

    Cole, Steven W. (Inventor)

    1992-01-01

    A method for frequency spectrum analysis of an unknown signal in real-time is discussed. The method is based upon integration of 1-bit samples of signal voltage amplitude corresponding to sine or cosine phases of a controlled center frequency clock which is changed after each integration interval to sweep the frequency range of interest in steps. Integration of samples during each interval is carried out over a number of cycles of the center frequency clock spanning a number of cycles of an input signal to be analyzed. The invention may be used to detect the frequency of at least two signals simultaneously. By using a reference signal of known frequency and voltage amplitude (added to the two signals for parallel processing in the same way, but in a different channel with a sampling at the known frequency and phases of the reference signal), the absolute voltage amplitude of the other two signals may be determined by squaring the sine and cosine integrals of each channel and summing the squares to obtain relative power measurements in all three channels and, from the known voltage amplitude of the reference signal, obtaining an absolute voltage measurement for the other two signals by multiplying the known voltage of the reference signal with the ratio of the relative power of each of the other two signals to the relative power of the reference signal.

  13. Energy spectrum and mass composition of primary cosmic radiation in the region above the knee from the GAMMA experiment

    NASA Astrophysics Data System (ADS)

    Martirosov, Romen

    The energy spectrum of the primary cosmic radiation in the energy range 1 - 100 PeV and the extensive air shower (EAS) characteristics obtained on the basis of the expanded data bank of the GAMMA experiment (Mt. Aragats, Armenia) are presented. With increased statistics we confirm our previous results on the energy spectrum. The spectral index above the knee is about -3.1, but at energies beyond 20 PeV a flattening of the spectrum is observed. The existence of the 'bump' at about 70 PeV is confirmed with a significance of more than 4{\\sigma}. In the energy range of 10 - 100 PeV the shower age becomes energy independent and we observe a direct proportionality of the EAS size to the primary energy. This suggests an approximately constant depth of the EAS maximum in this energy range. This is evidence in favour of an increasing average mass of primary particles at energies above 20 PeV. The additional source scenario, which is a possible explanation of the 'bump' in the spectrum, also leads to the conclusion of increasing mass of the primary cosmic rays. A comparison with the data of other experiments is presented.

  14. A High-Sensitivity Measurement of the MeV Gamma-Ray Spectrum of Cygnus X-1

    NASA Astrophysics Data System (ADS)

    McConnell, M. L.; Ryan, J. M.; Collmar, W.; Schönfelder, V.; Steinle, H.; Strong, A. W.; Bloemen, H.; Hermsen, W.; Kuiper, L.; Bennett, K.; Phlips, B. F.; Ling, J. C.

    2000-11-01

    The Compton Gamma Ray Observatory (CGRO) has observed the Cygnus region on several occasions since its launch in 1991. The data collected by the COMPTEL experiment on CGRO represent the most sensitive observations to date of Cygnus X-1 in the 0.75-30 MeV range. A spectrum accumulated by COMPTEL over 10 weeks of observation time shows significant evidence for emission extending out to several MeV. We have combined these data with contemporaneous data from both BATSE and OSSE to produce a broadband γ-ray spectrum, corresponding to the low X-ray state of Cygnus X-1, extending from 50 keV up to ~5 MeV. Although there is no evidence for any broad-line-like emissions in the MeV region, these data further confirm the presence of a hard tail at energies above several hundred keV. In particular, the spectrum at MeV energies can be described as a power law with a photon spectral index of α=-3.2, with no evidence for a cutoff at high energies. For the 200 keV-5 MeV spectrum, we provide a quantitative description of the underlying electron spectrum, in the context of a hybrid thermal/nonthermal model for the emission. The electron spectrum can be described by a thermal Maxwellian with a temperature of kTe=86 keV and a nonthermal power-law component with a spectral index of pe=4.5. The spectral data presented here should provide a useful basis for further theoretical modeling.

  15. Energy spectrum of medium energy gamma-rays from the galactic center region. [experimental design

    NASA Technical Reports Server (NTRS)

    Palmeira, R. A. R.; Ramanujarao, K.; Dutra, S. L. G.; Bertsch, D. L.; Kniffen, D. A.; Morris, D. J.

    1978-01-01

    A balloon-borne magnetic core digitized spark chamber with two assemblies of spark-chambers above and below the scintillation counters was used to measure the medium energy gamma ray flux from the galactic center region. Gamma ray calculations are based on the multiple scattering of the pair electrons in 15 aluminum plates interleaved in the spark chamber modules. Counting rates determined during ascent and at ceiling indicate the presence of diffuse component in this energy range. Preliminary results give an integral flux between 15 and 70 MeV compared to the differential points in other results.

  16. Decision Analysis of Dynamic Spectrum Access Rules

    SciTech Connect

    Juan D. Deaton; Luiz A. DaSilva; Christian Wernz

    2011-12-01

    A current trend in spectrum regulation is to incorporate spectrum sharing through the design of spectrum access rules that support Dynamic Spectrum Access (DSA). This paper develops a decision-theoretic framework for regulators to assess the impacts of different decision rules on both primary and secondary operators. We analyze access rules based on sensing and exclusion areas, which in practice can be enforced through geolocation databases. Our results show that receiver-only sensing provides insufficient protection for primary and co-existing secondary users and overall low social welfare. On the other hand, using sensing information between the transmitter and receiver of a communication link, provides dramatic increases in system performance. The performance of using these link end points is relatively close to that of using many cooperative sensing nodes associated to the same access point and large link exclusion areas. These results are useful to regulators and network developers in understanding in developing rules for future DSA regulation.

  17. The development of a new edition of the gamma-ray spectrum catalogues designed for presentation in electronic format

    SciTech Connect

    Heath, R.L.

    1997-11-01

    New editions of the original Gamma-ray Spectrum Catalogues are being prepared for publication in electronic format. The objective of this program is to produce versions of the Catalogues in CD-ROM format and as an Internet resource. Additions to the original content of the Catalogues will include integrated decay scheme drawings, tables of related decay data, and updated text on the techniques of gamma-ray spectrometry. Related decay data from the Evaluated Nuclear Structure Data File (ENSDF) are then added, and all data converted to the Adobe Acrobat (PDF) format for CD-ROM production and availability on the large-volume Ge detectors, alpha-particle spectra, prompt neutron capture and inelastic scattering gamma-ray spectra, and gross fission product spectra characteristic of fuel cycle waste materials. Characterization of radioactivity in materials is a requirement in many phases of radioactive waste management. Movement, shipping, treatment, all activities which involve handling of mixed waste or TRU categories of waste at all DOE sites will require that measurements and assessment documentation utilize basic nuclear data which are tracable to internationally accepted standard values. This program will involve the identification of data needs unique to the development and application of specialized detector systems for radioactive waste characterization. 8 refs., 8 figs.

  18. The development of a new edition of the gamma-ray spectrum catalogues designed for presentation in electronic format

    SciTech Connect

    Heath, R.L.

    1997-05-01

    New editions of the original Gamma-ray Spectrum Catalogues are being prepared for publication in electronic format. The objective of this program is to produce versions of the Catalogues in CD-ROM format and as an Internet resource. Additions to the original content of the Catalogues will include integrated decay scheme drawings, tables of related decay data, and updated text on the techniques of gamma-ray spectrometry. Related decay data from the Evaluated Nuclear Structure Data File (ENSDF) are then added, and all data converted to the Adobe Acrobat (PDF) format for CD-ROM production and availability on the Internet. At a later date the catalogues will be expanded to include spectra representing the response of large-volume Ge detectors, alpha-particle spectra, prompt neutron capture and inelastic scattering gamma-ray spectra, and gross fission product spectra characteristic of fuel cycle waste materials. Characterization of radioactivity in materials is a requirement in many phases of radioactive waste management. Movement, shipping, treatment, all activities which involve handling of mixed waste or TRU categories of waste at all DOE sites will require that measurements and assessment documentation utilize basic nuclear data which are tracable to internationally accepted standard values. This program will involve the identification of data needs unique to the development and application of specialized detector systems for radioactive waste characterization.

  19. Gamma ray pulsar analysis from photon probability maps

    NASA Technical Reports Server (NTRS)

    Brown, Lawrence E.; Clayton, Donald D.; Hartmann, Dieter H.

    1992-01-01

    A new method is presented of analyzing skymap-type gamma ray data. Each photon event is replaced by a probability distribution on the sky corresponding to the observing instrument's point spread function. The skymap produced by this process may be used for source detection or identification. Most important, the use of these photon weights for pulsar analysis promises significant improvement over traditional techniques.

  20. Formation of very hard electron and gamma-ray spectra of flat-spectrum radio quasars in the fast-cooling regime

    NASA Astrophysics Data System (ADS)

    Yan, Dahai; Zhang, Li; Zhang, Shuang-Nan

    2016-07-01

    In the external Compton scenario, we investigate the formation of a very hard electron spectrum in the fast-cooling regime, using a time-dependent emission model. It is shown that a very hard electron distribution, N^' }_e({γ ^' })∝ {γ ^' }^{-p}, with spectral index p ˜ 1.3 is formed below the minimum energy of injection electrons when inverse Compton scattering takes place in the Klein-Nishina regime, i.e. inverse Compton scattering of relativistic electrons on broad-line region radiation in flat-spectrum radio quasars. This produces a very hard gamma-ray spectrum and can explain in reasonable fashion the very hard Fermi-Large Area Telescope (LAT) spectrum of the flat-spectrum radio quasar 3C 279 during the extreme gamma-ray flare in 2013 December.

  1. A gamma-ray spectrometry analysis software environment.

    PubMed

    Lutter, G; Hult, M; Marissens, G; Stroh, H; Tzika, F

    2017-06-30

    At the JRC-Geel's RadioNuclide Metrology sector, a Monte Carlo code based on EGSnrc, and a general purpose calculation sheet implemented in Microsoft Excel(®), have been developed to make the quantitative gamma-ray spectrometry analysis of samples simpler and more robust. The further aim is that the software can be used by non-experts in gamma-ray spectrometry e.g. external researchers using JRC-Geel's facilities through the EUFRAT transnational access scheme. This paper presents the developed Monte Carlo software and the functionality included in the calculation sheet. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. A comparative analysis of gamma and hadron families at the superhigh energies recorded in experiment Pamir

    NASA Technical Reports Server (NTRS)

    Azimov, S. A.; Mulladjanov, E. J.; Nosov, A. N.; Nuritdinov, H.; Talipov, D. A.; Halilov, D. A.; Yuldashbaev, T. S.

    1985-01-01

    A comparative analysis of hadron and gamma families which have undergone the decascading procedure is made. Results are compared with different models of interactions. In hadron families with energies Summary E sub H sup gamma 20 TeV as well as in gamma families with energies Summary E sub gamma 70 TeV, increasing azimuthal anisotropy is observed.

  3. IMPLEMENTING THE STANDARD SPECTRUM METHOD FOR ANALYSIS OF β-γ COINCIDENCE SPECTRA

    SciTech Connect

    Biegalski, S.; Flory, Adam E.; Schrom, Brian T.; Ely, James H.; Haas, Derek A.; Bowyer, Ted W.; Hayes, James C.

    2011-09-14

    The standard deconvolution analysis tool (SDAT) algorithms were developed and tested at the University of Texas at Austin. These algorithms utilize the standard spectrum technique for spectral analysis of {beta}-{gamma} coincidence spectra for nuclear explosion monitoring. Work has been conducted under this contract to implement these algorithms into a useable scientific software package with a graphical user interface. Improvements include the ability to read in PHD formatted data, gain matching, and data visualization. New auto-calibration algorithms were developed and implemented based on 137Cs spectra for assessment of the energy vs. channel calibrations. Details on the user tool and testing are included.

  4. ENERGY-DEPENDENT GAMMA-RAY BURST PULSE WIDTH DUE TO THE CURVATURE EFFECT AND INTRINSIC BAND SPECTRUM

    SciTech Connect

    Peng, Z. Y.; Ma, L.; Zhao, X. H.; Yin, Y.; Bao, Y. Y.

    2012-06-20

    Previous studies have found that the width of the gamma-ray burst (GRB) pulse is energy dependent and that it decreases as a power-law function with increasing photon energy. In this work we have investigated the relation between the energy dependence of the pulse and the so-called Band spectrum by using a sample including 51 well-separated fast rise and exponential decay long-duration GRB pulses observed by BATSE (Burst and Transient Source Experiment on the Compton Gamma Ray Observatory). We first decompose these pulses into rise and decay phases and find that the rise widths and the decay widths also behave as a power-law function with photon energy. Then we investigate statistically the relations between the three power-law indices of the rise, decay, and total width of the pulse (denoted as {delta}{sub r}, {delta}{sub d}, and {delta}{sub w}, respectively) and the three Band spectral parameters, high-energy index ({alpha}), low-energy index ({beta}), and peak energy (E{sub p} ). It is found that (1) {alpha} is strongly correlated with {delta}{sub w} and {delta}{sub d} but seems uncorrelated with {delta}{sub r}; (2) {beta} is weakly correlated with the three power-law indices, and (3) E{sub p} does not show evident correlations with the three power-law indices. We further investigate the origin of {delta}{sub d}-{alpha} and {delta}{sub w}-{alpha}. We show that the curvature effect and the intrinsic Band spectrum could naturally lead to the energy dependence of the GRB pulse width and also the {delta}{sub d}-{alpha} and {delta}{sub w}-{alpha} correlations. Our results hold so long as the shell emitting gamma rays has a curved surface and the intrinsic spectrum is a Band spectrum or broken power law. The strong {delta}{sub d}-{alpha} correlation and inapparent correlations between {delta}{sub r} and the three Band spectral parameters also suggest that the rise and decay phases of the GRB pulses have different origins.

  5. Analysis of Data from the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Kniffen, Donald A.; Elliott, William W.

    1999-01-01

    The final report consists of summaries of work proposed, work accomplished, papers and presentations published and continuing work regarding the cooperative agreement. The work under the agreement is based on high energy gamma ray source data analysis collected from the Energetic Gamma-Ray Experiment Telescope (EGRET).

  6. Prompt gamma analysis of chlorine in concrete for corrosion study.

    PubMed

    Naqvi, A A; Nagadi, M M; Al-Amoudi, O S B

    2006-02-01

    Measurement of chlorine in concrete is very important for studying of corrosion of reinforcing steel in concrete. Corrosion of reinforcing steel is primarily ascribed to the penetration of chloride ions to the steel surface. Preventive measures for avoiding concrete structure reinforcement corrosion requires monitoring the chloride ion concentration in concrete so that its concentration does not exceed a threshold limit to initiate reinforcement concrete corrosion. An accelerator based prompt gamma neutron activation analysis (PGNAA) setup has been developed for non-destructive analysis of elemental composition of concrete samples. The setup has been used to measure chlorine concentration in concrete samples over a 1-3 wt% concentration range. Although a strong interference has been observed between the chlorine gamma-rays and calcium gamma-rays from concrete, the chlorine concentration in concrete samples has been successfully measured using the 1.164 and 7.643 MeV chlorine gamma-rays. The experimental data were compared with the results of the Monte Carlo simulations. An excellent agreement has been achieved between the experimental data and results of Monte Carlo simulations. The study has demonstrated the successful use of the accelerator-based PGNAA setup in non-destructive analysis of chlorine in concrete samples.

  7. 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.

  8. GammaLib and ctools. A software framework for the analysis of astronomical gamma-ray data

    NASA Astrophysics Data System (ADS)

    Knödlseder, J.; Mayer, M.; Deil, C.; Cayrou, J.-B.; Owen, E.; Kelley-Hoskins, N.; Lu, C.-C.; Buehler, R.; Forest, F.; Louge, T.; Siejkowski, H.; Kosack, K.; Gerard, L.; Schulz, A.; Martin, P.; Sanchez, D.; Ohm, S.; Hassan, T.; Brau-Nogué, S.

    2016-08-01

    The field of gamma-ray astronomy has seen important progress during the last decade, yet to date no common software framework has been developed for the scientific analysis of gamma-ray telescope data. We propose to fill this gap by means of the GammaLib software, a generic library that we have developed to support the analysis of gamma-ray event data. GammaLib was written in C++ and all functionality is available in Python through an extension module. Based on this framework we have developed the ctools software package, a suite of software tools that enables flexible workflows to be built for the analysis of Imaging Air Cherenkov Telescope event data. The ctools are inspired by science analysis software available for existing high-energy astronomy instruments, and they follow the modular ftools model developed by the High Energy Astrophysics Science Archive Research Center. The ctools were written in Python and C++, and can be either used from the command line via shell scripts or directly from Python. In this paper we present the GammaLib and ctools software versions 1.0 that were released at the end of 2015. GammaLib and ctools are ready for the science analysis of Imaging Air Cherenkov Telescope event data, and also support the analysis of Fermi-LAT data and the exploitation of the COMPTEL legacy data archive. We propose using ctools as the science tools software for the Cherenkov Telescope Array Observatory.

  9. Reanalysis of the Apollo cosmic gamma-ray spectrum in the 0.3 to 10 MeV energy region

    NASA Technical Reports Server (NTRS)

    Trombka, J. I.; Dyer, C. S.; Evans, L. G.; Bielefeld, M. J.; Seltzer, S. M.; Metzger, A. E.

    1976-01-01

    Additional data obtained from the Apollo-16 and -17 missions, together with collateral calculations on background radiation effects, have enabled an improved subtraction of unwanted backgrounds from the diffuse cosmic gamma-ray data previously reported from Apollo-15. As a result, the 1- to 10-MeV spectrum is lowered significantly and connects smoothly with recent data at other energies. The inflection reported previously is much less pronounced and has no more than a 1.5-sigma significance. Sky occultation by the Apollo-16 spacecraft shows the bulk of the 0.3- to 1-MeV radiation to be diffuse. The analysis of spurious backgrounds points to important improvements for future experiments designed for this spectral region.

  10. An upper limit on interstellar C IV in the spectrum of gamma-2 Velorum

    NASA Technical Reports Server (NTRS)

    Lengyel-Frey, D.; Stecher, T. P.; West, D. K.

    1975-01-01

    An upper limit on the column density of C IV along the line of sight to gamma-2 Vel is derived from upper limits placed on the equivalent widths of the interstellar C IV doublet with rest wavelengths at 1548.20 A and 1550.77 A. A lower limit of 250,000 K is calculated for the electron temperature of O VI emitting regions by combining the C IV results with a measurement of the column density of interstellar O VI for the same star and using calculations for the relative ionization of some abundant elements as a function of electron temperature in a low-density plasma. Since gamma-2 Vel is in the central part of the Gum Nebula, the high temperature suggested by these results is shown to support the idea that a high-temperature phase of the interstellar medium, possibly maintained by supernova explosions, may exist.-

  11. Spectrum of {gamma} rays connecting superdeformed and normal states in {sup 192}Hg

    SciTech Connect

    Henry, R.G.; Lauritsen, T.; Khoo, T.L.

    1995-08-01

    Almost a hundred superdeformed bands were found in the mass 150 and 190 regions. Nevertheless, the energies and spins of the SD levels are still not measured (with one possible exception). Many attempts were made to decipher the highly-fragmented pathways connecting SD and normal states, but with hitherto no success. We adopted a new approach that consists of characterizing the overall spectral shape of the {gamma} rays linking SD and normal states.

  12. High-energy gamma-ray emission from solar flares: Constraining the accelerated proton spectrum

    NASA Technical Reports Server (NTRS)

    Alexander, David; Dunphy, Philip P.; Mackinnon, Alexander L.

    1994-01-01

    Using a multi-component model to describe the gamma-ray emission, we investigate the flares of December 16, 1988 and March 6, 1989 which exhibited unambiguous evidence of neutral pion decay. The observations are then combined with theoretical calculations of pion production to constrain the accelerated proton spectra. The detection of pi(sup 0) emission alone can indicate much about the energy distribution and spectral variation of the protons accelerated to pion producing energies. Here both the intensity and detailed spectral shape of the Doppler-broadened pi(sup 0) decay feature are used to determine the spectral form of the accelerated proton energy distribution. The Doppler width of this gamma-ray emission provides a unique diagnostic of the spectral shape at high energies, independent of any normalisation. To our knowledge, this is the first time that this diagnostic has been used to constrain the proton spectra. The form of the energetic proton distribution is found to be severely limited by the observed intensity and Doppler width of the pi(sup 0) decay emission, demonstrating effectively the diagnostic capabilities of the pi(sup 0) decay gamma-rays. The spectral index derived from the gamma-ray intensity is found to be much harder than that derived from the Doppler width. To reconcile this apparent discrepancy we investigate the effects of introducing a high-energy cut-off in the accelerated proton distribution. With cut-off energies of around 0.5-0.8 GeV and relatively hard spectra, the observed intensities and broadening can be reproduced with a single energetic proton distribution above the pion production threshold.

  13. Experience with a General Gamma-Ray Isotopic Analysis Approach

    SciTech Connect

    Ruhter, W D

    2003-06-18

    The gamma-ray data analysis methodology originally developed for the MGA code to determine the relative detection efficiency curve may also be used to determine the relative amounts of the isotopes being measured. This analysis approach is based on the fact that the intensity of any given gamma ray from a sample is determined by the amount of the emitting isotope present in the sample, the emission probability for the gamma ray being measured, the sample self attenuation, the attenuation due to absorbers between the sample and detector, and the detector efficiency. An equation can be written that describes a measured gamma-ray peak intensity in terms of these parameters. By selecting appropriate gamma-ray peaks from the isotopes of interest, we can solve a set of equations for the values of the parameters in any particular measurement including the relative amounts of the selected isotopes. The equations representing the peak intensities are very nonlinear and require an iterative least squares method to solve. We have developed software to ensure that during the iterative process the parameters stay within their appropriate ranges and converge properly in solving the set of equations under various measurement conditions. We have utilized and reported on this approach for determining the plutonium isotopic abundances in samples enriched in Pu-238 and to determine the U-235 enrichment of uranium samples in thick-walled containers. Recently, we have used this approach to determine the plutonium isotopic abundances of plutonium samples in thick-walled containers. We will report on this most recent application, and how this general approach can be adapted quickly to any isotopic analysis problem.

  14. [Backscattering spectrum analysis of nonspheroid soot particle].

    PubMed

    Xing, Jian; Sun, Xiao-gang; Yuan, Gui-bin; Qi, Xu; Tang, Hong

    2010-08-01

    In the process of measuring soot concentration and grain diameter, the backscattering spectrum of soot particle model was calculated to ascertain and analyze main effective factor of backscattering intensity. In the present paper, ellipsoid, column and generalized Chebyshev, three nonspheroid models, were selected according to micrograph of practical soot particle, which aims to simulate practical soot particle with equivalent diameter of about 1 microm. T-matrix method was used to calculate backscattering spectrum of the three nonspheriod models, and the main effective factor curves of intensity were obtained, too. Both numerical computer simulations and experimental results illustrate that nonspheroid particle backscattering intensity is stronger than that of spheroid particle in the visible/infrared spectrum band, especially for generalized Chebyshev model, whose backscattering intensity can be even 3.5 times higher than that of forward scattering. Meanwhile, the absorbency non-spheroid particle (complex refractive index m = 1.57 - 0.56i) backscattering intensity is stronger than that of non-absorbency nonspheriod particle (complex refractive index m = 1.57 - 0.001i). Furthermore, with the increase in particle equivalent radius, the light source wavelength also needs to be increase to obtain more light intensity information. The backscattering light spectrum information provides a reasonable basis for selecting light source and measure angle.

  15. Spectrum analysis for introductory musical acoustics

    NASA Astrophysics Data System (ADS)

    Smedley, John E.

    1998-02-01

    A "real time" fast Fourier transform spectrum analyzer facilitates several experiments for an introductory course in musical acoustics. With its rapidly updated display, the time-dependent vibrations of an aluminum bar are easily studied. Using longer time acquisitions and correspondingly higher resolution facilitates the study of string inharmonicities, resonant energy transfer, and sound radiation patterns in guitar acoustics.

  16. Angular Signatures of Dark Matter in the Diffuse Gamma Ray Spectrum

    SciTech Connect

    Hooper, Dan; Serpico, Pasquale D.; /Fermilab

    2007-02-01

    Dark matter annihilating in our Galaxy's halo and elsewhere in the universe is expected to generate a diffuse flux of gamma rays, potentially observable with next generation satellite-based experiments, such as GLAST. In this article, we study the signatures of dark matter in the angular distribution of this radiation. Pertaining to the extragalactic contribution, we discuss the effect of the motion of the solar system with respect to the cosmological rest frame, and anisotropies due to the structure of our local universe. For the gamma ray flux from dark matter in our own Galactic halo, we discuss the effects of the offset position of the solar system, the Compton-Getting effect, the asphericity of the Milky Way halo, and the signatures of nearby substructure. We explore the prospects for the detection of these features by the GLAST satellite and find that, if {approx} 10% or more of the diffuse gamma ray background observed by EGRET is the result of dark matter annihilations, then GLAST should be sensitive to anisotropies down to the 0.1% level. Such precision would be sufficient to detect many, if not all, of the signatures discussed in this paper.

  17. [Measurement and analysis of absorption spectrum of human blood].

    PubMed

    Zhao, Zhi-Min; Xin, Yu-Jun; Wang, Le-Xin; Zhu, Wei-Hua; Zheng, Min; Guo, Xin

    2008-01-01

    The present paper puts forward a method of disease diagnosis by using the technology of spectrum analysis of human blood serum. The generation mechanism of absorption spectrum is explained and the absorption spectra of the normal blood serum and the sick blood serum are listed from the experiments of absorption spectrometry. Though the value of absorbency of the sick blood serum is almost equal to that of the normal blood serum in the most absorption spectra, there are some differences around 278 nm in the absorption spectrum. The absorbency of the blood serum with hyperglycemia is greater than that of the normal blood serum at 285 nm in the spectrum, and besides, there comes a peak shift of absorption with hyperglycemia. In the absorption spectrum of the blood serum with hypercholesterolemia, there is a clear absorption peak at 414 nm. However there is not any peak at that wavelength in the absorption spectrum of the normal blood serum. Through comparing the characters of the spectrum, we can judge if the blood sample is or not, and this blood analysis is a new method for the diagnosis of disease. Compared with other methods of blood measurements, the method of absorption spectrum analysis of blood serum presented in this paper, is more convenient for measurement, simpler for analysis, and easier to popularize.

  18. Nuclear fuel microsphere gamma analyzer

    DOEpatents

    Valentine, Kenneth H.; Long, Jr., Ernest L.; Willey, Melvin G.

    1977-01-01

    A gamma analyzer system is provided for the analysis of nuclear fuel microspheres and other radioactive particles. The system consists of an analysis turntable with means for loading, in sequence, a plurality of stations within the turntable; a gamma ray detector for determining the spectrum of a sample in one section; means for analyzing the spectrum; and a receiver turntable to collect the analyzed material in stations according to the spectrum analysis. Accordingly, particles may be sorted according to their quality; e.g., fuel particles with fractured coatings may be separated from those that are not fractured, or according to other properties.

  19. Analysis of data from the energetic gamma-ray experiment of the Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Kniffen, Donald A.

    1995-01-01

    The work under the Grant has involved continued participation with the Compton Gamma Ray Observatory Energetic Gamma-Ray Experiment Telescope (EGRET) Team in the analysis of data obtained during instrument operations and the preparation of scientific papers and proposals for future observations. The EGRET team continues to submit IAU Astronomical telegrams and present many papers at scientific meetings. The EGRET Team was also successful on many proposals for the Cycle 4 portion of the mission, including long high galactic latitude studies of the diffuse extragalactic radiation in both the Northern and Southern Galactic Sky. These studies will be used in an effort to establish whether this radiation is truly diffuse or the sum of radiation from unresolved discrete sources such as radio-loud quasars. Data analysis is complete for papers on behalf of the EGRET Team by the author on general sources in the anticenter region of the galaxy, with galactic latitudes from 125 to 220 deg. A paper on this subject is in preparation for publication in the Astrophysical Journal. Another is being prepared on EGRET observations of the COS-B source 2CG135. Work is in progress for a third on the contribution of unresolved pulsars to the galactic diffuse radiations; two other papers are in analysis phase. A number of papers have been published in the last reporting period, and several others are in press currently. A summary of the publications is described.

  20. Prompt Gamma-Ray Neutron Activation Analysis (PGNAA) for Elemental Analysis

    SciTech Connect

    Robin P. Gardner

    2006-04-11

    This research project was to improve the prompt gamma-ray neutron activation analysis (PGNAA) measurement approach for bulk analysis, oil well logging, and small sample thermal enutron bean applications.

  1. Analysis of relaxation in terahertz spectrum

    NASA Astrophysics Data System (ADS)

    Wang, Jia-chun; Lu, Yu-min; Shi, Min; Zhao, Da-peng; Xu, Bo; Chen, Zong-sheng

    2011-08-01

    There is a close correlation between dielectric loss and complex dielectric constant of non-magnetism medium, and the former is the macroscopical representation for the later. Relaxation is one of important cause of the dielectric loss. This paper educes the complex dielectric constant and complex refractive index of non-magnetism medium in Terahertz spectrum on the base of initial Drude Model, analyzing their characteristics; it also calculates the Argand Picture of Drude Model, comparing with the counterpoint of Debye Model.

  2. Analysis of Data from the Energetic Gamma-ray Experiment on the Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Kniffen, Donald A.

    1996-01-01

    The work under the Grant has involved participation with the Compton Gamma Ray Observatory Energetic Gamma-Ray Experiment Telescope (EGRET) Team in the analysis of data obtained during instrument operations and the preparation of scientific papers and proposals for future observations. The Principal Investigator (PI) has been a co-author on a total of 90 papers published in refereed professional journals since the beginning of 1991, plus many other non-refereed publications, and contributed and invited papers at professional meetings and IAU telegrams. On seven of these papers he was the lead author. The EGRET team continues to submit IAU Astronomical telegrams and present many papers at scientific meetings. The effort by the PI has involved working remotely by internet connection on the Goddard Space Flight Center Computers where the EGRET data are archived. Students have monitored instrument performance, performed Viewing Period Analyses and analyzed data remotely. The PI has completed the detailed analysis of over 20 viewing periods to search for point sources and this work has been used in developing the first and second EGRET catalog of sources, published in Supplements to the Astrophysical Journal.

  3. Analysis of data from the energetic gamma-ray experiment on the gamma ray observatory

    NASA Technical Reports Server (NTRS)

    Kniffen, Donald A.

    1993-01-01

    The work under the Grant has involved continued participation with the Compton Gamma Ray Observatory Energetic Gamma-Ray Experiment Telescope (EGRET) Team in the analysis of data obtained during instrument operations and the preparation of scientific papers and proposals for future observations. The EGRET team was also successful on many proposals for the Phase 3 portion of the mission, including long high galactic latitude studies of the diffuse extragalactic radiation. These studies will be used in a effort to establish whether this radiation is truly diffuse or the sum of radiation from unresolved discrete sources such as radio-loud quasars. The effort involved working remotely by internet connection on the Goddard Space Flight Center Computers where the EGRET data are archived. Students have monitored instrument performance and analyzed data remotely and will continue to do so. The PI has completed the detailed analysis of five viewing periods to search for point sources and this work has been used in developing the first EGRET catalog of sources, soon to be released.

  4. CISAPS: Complex Informational Spectrum for the Analysis of Protein Sequences.

    PubMed

    Chrysostomou, Charalambos; Seker, Huseyin; Aydin, Nizamettin

    2015-01-01

    Complex informational spectrum analysis for protein sequences (CISAPS) and its web-based server are developed and presented. As recent studies show, only the use of the absolute spectrum in the analysis of protein sequences using the informational spectrum analysis is proven to be insufficient. Therefore, CISAPS is developed to consider and provide results in three forms including absolute, real, and imaginary spectrum. Biologically related features to the analysis of influenza A subtypes as presented as a case study in this study can also appear individually either in the real or imaginary spectrum. As the results presented, protein classes can present similarities or differences according to the features extracted from CISAPS web server. These associations are probable to be related with the protein feature that the specific amino acid index represents. In addition, various technical issues such as zero-padding and windowing that may affect the analysis are also addressed. CISAPS uses an expanded list of 611 unique amino acid indices where each one represents a different property to perform the analysis. This web-based server enables researchers with little knowledge of signal processing methods to apply and include complex informational spectrum analysis to their work.

  5. CISAPS: Complex Informational Spectrum for the Analysis of Protein Sequences

    PubMed Central

    Seker, Huseyin; Aydin, Nizamettin

    2015-01-01

    Complex informational spectrum analysis for protein sequences (CISAPS) and its web-based server are developed and presented. As recent studies show, only the use of the absolute spectrum in the analysis of protein sequences using the informational spectrum analysis is proven to be insufficient. Therefore, CISAPS is developed to consider and provide results in three forms including absolute, real, and imaginary spectrum. Biologically related features to the analysis of influenza A subtypes as presented as a case study in this study can also appear individually either in the real or imaginary spectrum. As the results presented, protein classes can present similarities or differences according to the features extracted from CISAPS web server. These associations are probable to be related with the protein feature that the specific amino acid index represents. In addition, various technical issues such as zero-padding and windowing that may affect the analysis are also addressed. CISAPS uses an expanded list of 611 unique amino acid indices where each one represents a different property to perform the analysis. This web-based server enables researchers with little knowledge of signal processing methods to apply and include complex informational spectrum analysis to their work. PMID:25632276

  6. A Sensitivity Analysis of the Logarithmic-Poisson-Gamma Distribution.

    DTIC Science & Technology

    1981-12-01

    NUMBER 2. GOVT ACCE ION NO. RECIPIENT’S CATALOG NUMBER 4. TITLE (ond Suabtie) S . TYPE OF REPORT & PERIOD COVERED A Sensitivity Analysis of Logarithmic...Poisson NEM Gamma DistributionINEM 6. PERFORMING 01G. REPORT NUMBER ____________________________________ WP-81 -05 7. AUTHOR(.) S . CONTACT OR GRANT...NuMBER( s ) W. Steven Denuiy, and Steven Nahmias F33600-8O-C-0530 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK( AREA

  7. Analyses of Oxyanion Materials by Prompt Gamma Activation Analysis

    SciTech Connect

    Firestone, Richard B; Perry, D.L.; English, G.A.; Firestone, R.B.; Leung, K.-N.; Garabedian, G.; Molnar, G.L.; Revay, Zs.

    2008-03-24

    Prompt gamma activation analysis (PGAA) has been used to analyze metal ion oxyanion materials that have multiple applications, including medicine, materials, catalysts, and electronics. The significance for the need for accurate, highly sensitive analyses for the materials is discussed in the context of quality control of end products containing the parent element in each material. Applications of the analytical data for input to models and theoretical calculations related to the electronic and other properties of the materials are discussed.

  8. Calculation of the spectrum of {gamma} rays connecting superdeformed and normally deformed nuclear states

    SciTech Connect

    Dossing, T.; Khoo, T.L.; Lauritsen, T.

    1995-08-01

    The decay out of superdeformed states occurs by coupling to compound nuclear states of normal deformation. The coupling is very weak, resulting in mixing of the SD state with one or two normal compound states. With a high energy available for decay, a statistical spectrum ensues. The shape of this statistical spectrum contains information on the level densities of the excited states below the SD level. The level densities are sensitively affected by the pair correlations. Thus decay-out of a SD state (which presents us with a means to start a statistical cascade from a highly-excited sharp state) provides a method for investigating the reduction of pairing with increasing thermal excitation energy.

  9. Lunar elemental analysis obtained from the Apollo gamma-ray and X-ray remote sensing experiment

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    Gamma ray and X-ray spectrometers carried in the service module of the Apollo 15 and 16 spacecraft were employed for compositional mapping of the lunar surface. The measurements involved the observation of the intensity and characteristics energy distribution of gamma rays and X-rays emitted from the lunar surface. A large scale compositional map of over 10 percent of the lunar surface was obtained from an analysis of the observed spectra. The objective of the X-ray experiment was to measure the K spectral lines from Mg, Al, and Si. Spectra were obtained and the data were reduced to Al/Si and Mg/Si intensity ratios and ultimately to chemical ratios. The objective of the gamma-ray experiment was to measure the natural and cosmic ray induced activity emission spectrum. At this time, the elemental abundances for Th, U, K, Fe, Ti, Si, and O have been determined over a number of major lunar regions.

  10. Spectrum Analysis of Some Kinetic Equations

    NASA Astrophysics Data System (ADS)

    Yang, Tong; Yu, Hongjun

    2016-11-01

    We analyze the spectrum structure of some kinetic equations qualitatively by using semigroup theory and linear operator perturbation theory. The models include the classical Boltzmann equation for hard potentials with or without angular cutoff and the Landau equation with {γ≥q-2}. As an application, we show that the solutions to these two fundamental equations are asymptotically equivalent (mod time decay rate {t^{-5/4}}) as {tto∞} to that of the compressible Navier-Stokes equations for initial data around an equilibrium state.

  11. 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.

  12. [Infrared absorption spectrum analysis and its application to blood].

    PubMed

    Wang, Le-xin; Zhao, Zhi-min; Yao, Hong-bing; Chen, Yu-ming; Shi, Lei; Gao, Yong

    2002-12-01

    The technology of infrared absorption spectrum is a branch of optical ment measurement technology, and the research on the application of infrared spectrum plays an important role in the development of technology of optical measurement. In this paper, the analysis technology of blood infrared absorption spectrum is presented. By comparison, the difference of the spectra between normal and abnormal blood samples was obtained. The infrared absorption spectra of normal blood sample and abnormal blood sample were detected, and the differences between the spectra are presented. And the analysis results of the infrared absorption spectra of normal whole blood, serum and hyperglycemia are presented also. All of these provide an experimental basis for the diagnosis of diseases, which is valuable for application. This technology features easy operation, convenient analysis and suitability for advanced experiment. The work offers a new way in the research on the application of infrared absorption spectrum.

  13. Bayesian Block Analysis of Terrestrial Gamma-ray Flashes Detected by the Gamma-ray Burst Monitor

    NASA Astrophysics Data System (ADS)

    Roberts, O.; Fitzpatrick, G.; McBreen, S.; Briggs, M. S.

    2014-12-01

    The Gamma-ray Burst Monitor (GBM) is one of two instruments aboard the Fermi Gamma-ray Space Telescope. Since the launch of the spacecraft in 2008, a sequence of flight software enhancements and new observing modes have resulted in the detection of over 2500 Terrestrial Gamma-ray Flashes (TGFs) by GBM. As a result, a catalogue of TGFs will be published and released online to provide the community with information on the most important characteristics of these TGFs. We will present a Bayesian Block analysis of the TGFs of this catalogue, obtaining for this large sample size the durations, peak times, hardness ratios, and delays between soft and hard counts.

  14. Scintillation gamma spectrometer for analysis of hydraulic fracturing waste products.

    PubMed

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

    2015-01-01

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

  15. 78 FR 31568 - Proposed Collection; 60-day Comment Request: Autism Spectrum Disorder Research Portfolio Analysis

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-24

    ... Collection; 60-day Comment Request: Autism Spectrum Disorder Research Portfolio Analysis SUMMARY: In... this publication. Proposed Collection: Autism Spectrum Disorder (ASD) Research Portfolio Analysis,...

  16. Spectrum analysis with quantum dynamical systems

    NASA Astrophysics Data System (ADS)

    Ng, Shilin; Ang, Shan Zheng; Wheatley, Trevor A.; Yonezawa, Hidehiro; Furusawa, Akira; Huntington, Elanor H.; Tsang, Mankei

    2016-04-01

    Measuring the power spectral density of a stochastic process, such as a stochastic force or magnetic field, is a fundamental task in many sensing applications. Quantum noise is becoming a major limiting factor to such a task in future technology, especially in optomechanics for temperature, stochastic gravitational wave, and decoherence measurements. Motivated by this concern, here we prove a measurement-independent quantum limit to the accuracy of estimating the spectrum parameters of a classical stochastic process coupled to a quantum dynamical system. We demonstrate our results by analyzing the data from a continuous-optical-phase-estimation experiment and showing that the experimental performance with homodyne detection is close to the quantum limit. We further propose a spectral photon-counting method that can attain quantum-optimal performance for weak modulation and a coherent-state input, with an error scaling superior to that of homodyne detection at low signal-to-noise ratios.

  17. Baryon Spectrum Analysis using Covariant Constraint Dynamics

    NASA Astrophysics Data System (ADS)

    Whitney, Joshua; Crater, Horace

    2012-03-01

    The energy spectrum of the baryons is determined by treating each of them as a three-body system with the interacting forces coming from a set of two-body potentials that depend on both the distance between the quarks and the spin and orbital angular momentum coupling terms. The Two Body Dirac equations of constraint dynamics derived by Crater and Van Alstine, matched with the quasipotential formalism of Todorov as the underlying two-body formalism are used, as well as the three-body constraint formalism of Sazdjian to integrate the three two-body equations into a single relativistically covariant three body equation for the bound state energies. The results are analyzed and compared to experiment using a best fit method and several different algorithms, including a gradient approach, and Monte Carlo method. Results for all well-known baryons are presented and compared to experiment, with good accuracy.

  18. Terahertz wave spectrum analysis of microstrip structure

    NASA Astrophysics Data System (ADS)

    Song, Mei-jing; Li, Jiu-sheng

    2012-03-01

    Terahertz wave is a kind of electromagnetic wave ranging from 0.1~10THz, between microwave and infrared, which occupies a special place in the electromagnetic spectrum. Terahertz radiation has a strong penetration for many media materials and nonpolar substance, for example, dielectric material, plastic, paper carton and cloth. In recent years, researchers around the world have paid great attention on terahertz technology, such as safety inspection, chemical biology, medical diagnosis and terahertz wave imaging, etc. Transmission properties of two-dimensional metal microstrip structures in the terahertz regime are presented and tested. Resonant terahertz transmission was demonstrated in four different arrays of subwavelength microstrip structure patterned on semiconductor. The effects of microstrip microstrip structure shape were investigated by using terahertz time-domain spectroscopy system. The resonant terahertz transmission has center frequency of 2.05 THz, transmission of 70%.

  19. Terahertz wave spectrum analysis of microstrip structure

    NASA Astrophysics Data System (ADS)

    Song, Mei-jing; Li, Jiu-sheng

    2011-11-01

    Terahertz wave is a kind of electromagnetic wave ranging from 0.1~10THz, between microwave and infrared, which occupies a special place in the electromagnetic spectrum. Terahertz radiation has a strong penetration for many media materials and nonpolar substance, for example, dielectric material, plastic, paper carton and cloth. In recent years, researchers around the world have paid great attention on terahertz technology, such as safety inspection, chemical biology, medical diagnosis and terahertz wave imaging, etc. Transmission properties of two-dimensional metal microstrip structures in the terahertz regime are presented and tested. Resonant terahertz transmission was demonstrated in four different arrays of subwavelength microstrip structure patterned on semiconductor. The effects of microstrip microstrip structure shape were investigated by using terahertz time-domain spectroscopy system. The resonant terahertz transmission has center frequency of 2.05 THz, transmission of 70%.

  20. Spectrum and variation of gamma-ray emission from the galactic center region

    NASA Technical Reports Server (NTRS)

    Riegler, G. R.; Ling, J. C.; Mahoney, W. A.; Wheaton, W. A.; Jacobson, A. S.

    1982-01-01

    Continuum emission at 60-300 keV from the galactic center region was observed to decrease in intensity by 45 percent and to show a spectrum steepening between fall 1979 and spring 1980. At the same time 511 keV positron annihilation radiation decreased by a comparable fraction. No variations over shorter time scales were detected. The observations are consistent with a model where positrons and hard X-rays are produced in an electromagnetic cascade near a massive black hole.

  1. Spectrum and variation of gamma-ray emission from the galactic center region

    NASA Technical Reports Server (NTRS)

    Riegler, G. R.; Ling, J. C.; Mahoney, W. A.; Wheaton, W. A.; Jacobson, A. S.

    1982-01-01

    Continuum emission at 60-300 keV from the galactic center region was observed to decrease in intensity by 45 percent and to show a spectrum steepening between fall 1979 and spring 1980. At the same time 511 keV positron annihilation radiation decreased by a comparable fraction. No variations over shorter time scales were detected. The observations are consistent with a model where positrons and hard X-rays are produced in an electromagnetic cascade near a massive black hole.

  2. Heart Sound Biometric System Based on Marginal Spectrum Analysis

    PubMed Central

    Zhao, Zhidong; Shen, Qinqin; Ren, Fangqin

    2013-01-01

    This work presents a heart sound biometric system based on marginal spectrum analysis, which is a new feature extraction technique for identification purposes. This heart sound identification system is comprised of signal acquisition, pre-processing, feature extraction, training, and identification. Experiments on the selection of the optimal values for the system parameters are conducted. The results indicate that the new spectrum coefficients result in a significant increase in the recognition rate of 94.40% compared with that of the traditional Fourier spectrum (84.32%) based on a database of 280 heart sounds from 40 participants. PMID:23429515

  3. Heart sound biometric system based on marginal spectrum analysis.

    PubMed

    Zhao, Zhidong; Shen, Qinqin; Ren, Fangqin

    2013-02-18

    This work presents a heart sound biometric system based on marginal spectrum analysis, which is a new feature extraction technique for identification purposes. This heart sound identification system is comprised of signal acquisition, pre-processing, feature extraction, training, and identification. Experiments on the selection of the optimal values for the system parameters are conducted. The results indicate that the new spectrum coefficients result in a significant increase in the recognition rate of 94.40% compared with that of the traditional Fourier spectrum (84.32%) based on a database of 280 heart sounds from 40 participants. 

  4. Spectrum of {gamma} rays from the decay of SD to normal states in {sup 191}Hg

    SciTech Connect

    Gassmann, D.; Khoo, T.L.; Lauritsen, T.

    1995-08-01

    In B.a.7. we propose that the statistical spectrum emitted from a sharp single excited state serves as a probe of pairing in excited states. A specific test of this proposal is the comparison of the spectra from even-even and odd-even nuclei. Whereas a pair gap exists in an even-even nucleus, it gets filled in an odd-even nucleus. Consequently, low-energy transitions can arise in the latter case, whereas they are calculated to be absent in the former case because very few levels exist in the cold gap region. In addition, transitions between 1.4 - 2.2 MeV, which {open_quotes}jump{close_quotes} across the gap, are predicted to have lower yield in the odd-even nuclei. Serendipitously, decay from a superdeformed state serves as a good initial excited sharp state. We extracted the spectrum pairwise-coincident with SD lines in {sup 191}Hg from Gammasphere data and compared it with the equivalent spectra from the even-even nuclei {sup 192,194}Hg. The differences that are predicted to occur are indeed observed. Thus, the data support our proposal that the reduction of pairing with thermal excitation energy can be probed with statistical decay spectra.

  5. Toward a fractal spectrum approach for neutron and gamma pulse shape discrimination

    NASA Astrophysics Data System (ADS)

    Liu, Ming-Zhe; Liu, Bing-Qi; Zuo, Zhuo; Wang, Lei; Zan, Gui-Bin; Tuo, Xian-Guo

    2016-06-01

    Accurately selecting neutron signals and discriminating γ signals from a mixed radiation field is a key research issue in neutron detection. This paper proposes a fractal spectrum discrimination approach by means of different spectral characteristics of neutrons and γ rays. Figure of merit and average discriminant error ratio are used together to evaluate the discrimination effects. Different neutron and γ signals with various noise and pulse pile-up are simulated according to real data in the literature. The proposed approach is compared with the digital charge integration and pulse gradient methods. It is found that the fractal approach exhibits the best discrimination performance, followed by the digital charge integration method and the pulse gradient method, respectively. The fractal spectrum approach is not sensitive to high frequency noise and pulse pile-up. This means that the proposed approach has superior performance for effective and efficient anti-noise and high discrimination in neutron detection. Supported by the National Natural Science Foundation of China (41274109), Sichuan Youth Science and Technology Innovation Research Team (2015TD0020), Scientific and Technological Support Program of Sichuan Province (2013FZ0022), and the Creative Team Program of Chengdu University of Technology.

  6. The X-Ray Time Variability and Spectrum of Gamma-Cassiopeiae X:0053+604

    NASA Astrophysics Data System (ADS)

    Parmar, A. N.; Israel, G. L.; Stella, L.; White, N. E.

    1993-08-01

    A 30 h duration EXOSAT observation made in 1985 December is used to examine the X-ray time variability and spectrum of the Be star γ Cassiopeiae (X 0053+604). We find that the X-ray lightcurve is dominated by irregular energy-independent flaring on time-scales ≳ 100 s. This flaring markedly decreases the sensitivity to any periodic signals. We find no evidence for the 6000 5 oscillations reported by Frontera et al. (1987) from an earlier EXOSAT observation. We suggest that these arise from statistical fluctuations in the red noise power. The X-ray spectrum of γ Cas can either be modeled by thermal emission from an optically thin plasma with a temperature of 12 keV, or by a cut-off power-law model with a narrow iron line at an energy of 6.67 keV. The origin of the X-ray emission in this system remains open since its spectral and temporal properties are consistent with both an acereting neutron star and a white dwarf while its high temperature argues against a coronal mechanism.

  7. Reference MWA EoR Power Spectrum analysis

    NASA Astrophysics Data System (ADS)

    Hazelton, Bryna; Pober, Jonathan; Beardsley, Adam; Morales, Miguel F.; Sullivan, Ian S.; MWA Collaboration

    2015-01-01

    Observations of the Epoch of Reionization using redshifted 21cm HI emission promise to provide sensitive new cosmological constraints in the next few years. The current generation of HI EoR telescopes are targeting a statistical detection of the EoR in the power spectrum of the 21cm emission. The principal challenge lies in extracting the faint cosmological signal in the face of bright foregrounds and instrumental systematics that threaten to overwhelm it.We present the UW EoR power spectrum code, the reference code for the MWA and the first power spectrum analysis to analytically propagate the error bars through the full data analysis pipeline. We demonstrate the sensitivity of the power spectrum as a diagnostic tool for identifying subtle systematics and show power spectra of the first season of MWA observations.

  8. Energy spectrum analysis - A model of echolocation processing. [in animals

    NASA Technical Reports Server (NTRS)

    Johnson, R. A.; Titlebaum, E. L.

    1976-01-01

    The paper proposes a frequency domain approach based on energy spectrum analysis of the combination of a signal and its echoes as the processing mechanism for the echolocation process used by bats and other animals. The mechanism is a generalized wide-band one and can account for the large diversity of wide-band signals used for orientation. The coherency in the spectrum of the signal-echo combination is shown to be equivalent to correlation.

  9. Energy spectrum analysis - A model of echolocation processing. [in animals

    NASA Technical Reports Server (NTRS)

    Johnson, R. A.; Titlebaum, E. L.

    1976-01-01

    The paper proposes a frequency domain approach based on energy spectrum analysis of the combination of a signal and its echoes as the processing mechanism for the echolocation process used by bats and other animals. The mechanism is a generalized wide-band one and can account for the large diversity of wide-band signals used for orientation. The coherency in the spectrum of the signal-echo combination is shown to be equivalent to correlation.

  10. {eta} Prime {yields}{pi}{sup 0}{gamma}{gamma} and {eta} Prime {yields}{eta}{gamma}{gamma}: A primer analysis

    SciTech Connect

    Escribano, Rafel

    2012-10-23

    The electromagnetic rare decays {eta} Prime {yields}{pi}{sup 0}{gamma}{gamma} and {eta} Prime {yields}{pi}{sup 0}{gamma}{gamma} are analysed for the first time and their predicted branching ratios given. The vector meson exchange dominant contribution is treated using Vector Meson Dominance and the scalar component is estimated by means of the Linear Sigma Model. The agreement between our calculation and the measurement of the related process {eta} Prime {yields}{pi}{sup 0}{gamma}{gamma} is a check of the procedure. Scalar meson effects are seen to be irrelevant for {eta} Prime {yields}{pi}{sup 0}{gamma}{gamma}, while a significant scalar contribution due to the {sigma}(500) resonance seems to emerge in the case of {eta} Prime {yields}{pi}{sup 0}{gamma}{gamma}. Future measurements coming from KLOE-2, Crystal Ball, WASA, and BES-III will elucidate if any of these processes carry an important scalar contribution or they are simply driven by the exchange of vector mesons.

  11. A pseudo-spectrum analysis of galaxy-galaxy lensing

    NASA Astrophysics Data System (ADS)

    Hikage, Chiaki; Oguri, Masamune

    2016-10-01

    We present the application of the pseudo-spectrum method to galaxy-galaxy lensing. We derive explicit expressions for the pseudo-spectrum analysis of the galaxy-shear cross-spectrum, which is the Fourier space counterpart of the stacked galaxy-galaxy lensing profile. The pseudo-spectrum method corrects observational issues such as the survey geometry, masks of bright stars and their spikes, and inhomogeneous noise, which distort the spectrum and also mix the E-mode and the B-mode signals. Using ray-tracing simulations in N-body simulations including realistic masks, we confirm that the pseudo-spectrum method successfully recovers the input galaxy-shear cross-spectrum. We also show that the galaxy-shear cross-spectrum has an excess covariance relative to the Gaussian covariance at small scales (k ≳ 1h Mpc-1) where the shot noise is dominated in the Gaussian approximation. We find that the excess is consistent with the expectation from the halo sample variance (HSV), which originates from the matter fluctuations at scales larger than the survey area. We apply the pseudo-spectrum method to the observational data of Canada-France-Hawaii Telescope Lensing survey shear catalogue and three different spectroscopic samples of Sloan Digital Sky Survey Luminous Red Galaxy, and Baryon Oscillation Spectroscopic Survey CMASS and LOWZ galaxies. The galaxy-shear cross-spectra are significantly detected at the level of 7-10σ using the analytic covariance with the HSV contribution included. We also confirm that the observed spectra are consistent with the halo model predictions with the halo occupation distribution parameters estimated from previous work. This work demonstrates the viability of galaxy-galaxy lensing analysis in the Fourier space.

  12. Optimisation of beryllium-7 gamma analysis following BCR sequential extraction.

    PubMed

    Taylor, A; Blake, W H; Keith-Roach, M J

    2012-03-30

    The application of cosmogenic (7)Be as a sediment tracer at the catchment-scale requires an understanding of its geochemical associations in soil to underpin the assumption of irreversible adsorption. Sequential extractions offer a readily accessible means of determining the associations of (7)Be with operationally defined soil phases. However, the subdivision of the low activity concentrations of fallout (7)Be in soils into geochemical fractions can introduce high gamma counting uncertainties. Extending analysis time significantly is not always an option for batches of samples, owing to the on-going decay of (7)Be (t(1/2)=53.3 days). Here, three different methods of preparing and quantifying (7)Be extracted using the optimised BCR three-step scheme have been evaluated and compared with a focus on reducing analytical uncertainties. The optimal method involved carrying out the BCR extraction in triplicate, sub-sampling each set of triplicates for stable Be analysis before combining each set and coprecipitating the (7)Be with metal oxyhydroxides to produce a thin source for gamma analysis. This method was applied to BCR extractions of natural (7)Be in four agricultural soils. The approach gave good counting statistics from a 24 h analysis period (~10% (2σ) where extract activity >40% of total activity) and generated statistically useful sequential extraction profiles. Total recoveries of (7)Be fell between 84 and 112%. The stable Be data demonstrated that the extraction procedure had a high reproducibility (<1% RSD), thus gamma counting uncertainties dominated the overall uncertainty. In addition, extractions of soil equilibrated with stable Be at a concentration below the Cation Exchange Capacity (CEC) of the soil demonstrated that doubling the soil:solution ratio to enhance the mass of soil used in a sequential extraction scheme affects the apparent distribution of approximately 10% of the total Be. At high concentration, stable Be was found to be a poor proxy for

  13. The effects of temperature on ESR spectrum of gamma-irradiated ammonium tartrate

    NASA Astrophysics Data System (ADS)

    Polat, Mustafa; Korkmaz, Mustafa

    2009-11-01

    Unirradiated ammonium tartrate (AT) samples do not exhibit any ESR signal. However, irradiation produces an unresolved singlet at g=2.0034±0.0006 with two shoulders at g1=2.0093±0.0006 and g2=2.0048±0.0006. The dose-response curve was found to increase linearly with the applied radiation doses in the range of 0.1-2.0 kGy and the slope of this curve was increased as the modulation amplitude increased. The activation energy value Ea=69.0±1.2 kJ/mol was calculated from Arrhenius plot for the radical species responsible from ESR spectrum of irradiated AT.

  14. The energy spectrum of anomalous X-ray pulsars and soft gamma-ray repeaters

    NASA Astrophysics Data System (ADS)

    Trümper, J. E.; Zezas, A.; Ertan, Ü.; Kylafis, N. D.

    2010-07-01

    Context. Anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) exhibit characteristic X-ray luminosities (both soft and hard) of around 1035 erg s-1 and characteristic power-law, hard X-ray spectra extending to about 200 keV. Two AXPs also exhibit pulsed radio emission. Aims: Assuming that AXPs and SGRs accrete matter from a fallback disk, we attempt to explain both the soft and the hard X-ray emission as the result of the accretion process. We also attempt to explain their radio emission or the lack of it. Methods: We test the hypothesis that the power-law, hard X-ray spectra are produced in the accretion flow mainly by bulk-motion Comptonization of soft photons emitted at the neutron star surface. Fallback disk models invoke surface dipole magnetic fields of 1012 - 1013 G, which is what we assume here. Results: Unlike normal X-ray pulsars, for which the accretion rate is highly super-Eddington, the accretion rate is approximately Eddington in AXPs and SGRs and thus the bulk-motion Comptonization operates efficiently. As an illustrative example we reproduce both the hard and the soft X-ray spectra of AXP 4U 0142+61 well using the XSPEC package compTB. Conclusions: Our model seems to explain both the hard and the soft X-ray spectra of AXPs and SGRs, as well as their radio emission or the lack of it, in a natural way. It might also explain the short bursts observed in these sources. On the other hand, it cannot explain the giant X-ray outbursts observed in SGRs, which may result from the conversion of magnetic energy in local multipole fields.

  15. Angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its dark matter interpretation

    SciTech Connect

    Fornasa, Mattia; Cuoco, Alessandro; Zavala, Jesús; Gaskins, Jennifer M.; Sánchez-Conde, Miguel A.; Gomez-Vargas, German; Komatsu, Eiichiro; Linden, Tim; Prada, Francisco; Zandanel, Fabio; Morselli, Aldo

    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 months 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.

  16. 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

  17. Angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its dark matter interpretation

    NASA Astrophysics Data System (ADS)

    Fornasa, Mattia; Cuoco, Alessandro; Zavala, Jesús; Gaskins, Jennifer M.; Sánchez-Conde, Miguel A.; Gomez-Vargas, German; Komatsu, Eiichiro; Linden, Tim; Prada, Francisco; Zandanel, Fabio; Morselli, Aldo

    2016-12-01

    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. We analyze energies between 0.5 and 500 GeV, extending the range considered in the previous measurement based on 22 months of data. We also compute, for the first time, the cross-correlation angular power spectrum between different energy bins. We find that the derived angular spectra are compatible with being Poissonian, i.e. constant in multipole. Moreover, 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.

  18. Acoustic spectrum analysis for gyro bearings

    NASA Astrophysics Data System (ADS)

    Heitzman, C. E.

    1981-08-01

    An acoustic system analyzer has been developed that will be an aid in bearing analysis for displacement gyros. The phenomenon of the Fourier Transform has made possible the development of an optical processor that operates by the interaction of light from a light emitting diode array sweeping across a binary frequency mask and through lenses onto a vidicon tube. This arrangement performs the Fourier Transform of large time samples of sound in a parallel process, preserving amplitude, frequency and phase information. The resultant information can then be entered into a computer for programmed analysis or displayed for visual analysis of the condition of gyro-bearings.

  19. Surface roughness monitoring by singular spectrum analysis of vibration signals

    NASA Astrophysics Data System (ADS)

    García Plaza, E.; Núñez López, P. J.

    2017-02-01

    This study assessed two methods for enhanced surface roughness (Ra) monitoring based on the application of singular spectrum analysis (SSA) to vibrations signals generated in workpiece-cutting tool interaction in CNC finish turning operations i.e., the individual analysis of principal components (I-SSA), and the grouping analysis of correlated principal components (G-SSA). Singular spectrum analysis is a non-parametric technique of time series analysis that decomposes a signal into a set of independent additive time series referred to as principal components. A number of experiments with different cutting conditions were performed to assess surface roughness monitoring using both of these methods. The results show that singular spectrum analysis of vibration signal processing discriminated the frequency ranges effective for predicting surface roughness. Grouping analysis of correlated principal components (G-SSA) proved to be the most efficient method for monitoring surface roughness, with optimum prediction and reliability results at a lower analytical-computational cost. Finally, the results show that singular spectrum analysis is an ideal method for analyzing vibration signals applied to the on-line monitoring of surface roughness.

  20. Singular spectrum analysis for time series with missing data

    USGS Publications Warehouse

    Schoellhamer, D.H.

    2001-01-01

    Geophysical time series often contain missing data, which prevents analysis with many signal processing and multivariate tools. A modification of singular spectrum analysis for time series with missing data is developed and successfully tested with synthetic and actual incomplete time series of suspended-sediment concentration from San Francisco Bay. This method also can be used to low pass filter incomplete time series.

  1. The Murchison Widefield Array 21 cm Power Spectrum Analysis Methodology

    NASA Astrophysics Data System (ADS)

    Jacobs, Daniel C.; Hazelton, B. J.; Trott, C. M.; Dillon, Joshua S.; Pindor, B.; Sullivan, I. S.; Pober, J. C.; Barry, N.; Beardsley, A. P.; Bernardi, G.; Bowman, Judd D.; Briggs, F.; Cappallo, R. J.; Carroll, P.; Corey, B. E.; de Oliveira-Costa, A.; Emrich, D.; Ewall-Wice, A.; Feng, L.; Gaensler, B. M.; Goeke, R.; Greenhill, L. J.; Hewitt, J. N.; Hurley-Walker, N.; Johnston-Hollitt, M.; Kaplan, D. L.; Kasper, J. C.; Kim, HS; Kratzenberg, E.; Lenc, E.; Line, J.; Loeb, A.; Lonsdale, C. J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Neben, A. R.; Thyagarajan, N.; Oberoi, D.; Offringa, A. R.; Ord, S. M.; Paul, S.; Prabu, T.; Procopio, P.; Riding, J.; Rogers, A. E. E.; Roshi, A.; Udaya Shankar, N.; Sethi, Shiv K.; Srivani, K. S.; Subrahmanyan, R.; Tegmark, M.; Tingay, S. J.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wu, C.; Wyithe, J. S. B.

    2016-07-01

    We present the 21 cm power spectrum analysis approach of the Murchison Widefield Array Epoch of Reionization project. In this paper, we compare the outputs of multiple pipelines for the purpose of validating statistical limits cosmological hydrogen at redshifts between 6 and 12. Multiple independent data calibration and reduction pipelines are used to make power spectrum limits on a fiducial night of data. Comparing the outputs of imaging and power spectrum stages highlights differences in calibration, foreground subtraction, and power spectrum calculation. The power spectra found using these different methods span a space defined by the various tradeoffs between speed, accuracy, and systematic control. Lessons learned from comparing the pipelines range from the algorithmic to the prosaically mundane; all demonstrate the many pitfalls of neglecting reproducibility. We briefly discuss the way these different methods attempt to handle the question of evaluating a significant detection in the presence of foregrounds.

  2. The REFLEX II galaxy cluster survey: power spectrum analysis

    NASA Astrophysics Data System (ADS)

    Balaguera-Antolínez, A.; Sánchez, Ariel G.; Böhringer, H.; Collins, C.; Guzzo, L.; Phleps, S.

    2011-05-01

    We present the power spectrum of galaxy clusters measured from the new ROSAT-ESO Flux-Limited X-Ray (REFLEX II) galaxy cluster catalogue. This new sample extends the flux limit of the original REFLEX catalogue to 1.8 × 10-12 erg s-1 cm-2, yielding a total of 911 clusters with ≥94 per cent completeness in redshift follow-up. The analysis of the data is improved by creating a set of 100 REFLEX II-catalogue-like mock galaxy cluster catalogues built from a suite of large-volume Λ cold dark matter (ΛCDM) N-body simulations (L-BASICC II). The measured power spectrum is in agreement with the predictions from a ΛCDM cosmological model. The measurements show the expected increase in the amplitude of the power spectrum with increasing X-ray luminosity. On large scales, we show that the shape of the measured power spectrum is compatible with a scale-independent bias and provide a model for the amplitude that allows us to connect our measurements with a cosmological model. By implementing a luminosity-dependent power-spectrum estimator, we observe that the power spectrum measured from the REFLEX II sample is weakly affected by flux-selection effects. The shape of the measured power spectrum is compatible with a featureless power spectrum on scales k > 0.01 h Mpc-1 and hence no statistically significant signal of baryonic acoustic oscillations can be detected. We show that the measured REFLEX II power spectrum displays signatures of non-linear evolution.

  3. Fermi LAT detection of renewed GeV gamma-ray activity associated with the flat-spectrum radio source PKS 2247-131

    NASA Astrophysics Data System (ADS)

    Gasparrini, D.

    2016-10-01

    The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed a renewed strong gamma-ray activity from a source positionally consistent with the flat-spectrum radio source PKS 2247-131 with coordinates RA=342.4983854 deg, Dec=-12.8546736 deg (J2000; Beasley et al. 2002, ApJS, 141, 13). Fermi-LAT already reported a flare on ATel #9285 but this source is not in any published LAT catalog and was not detected by AGILE or EGRET.

  4. Fermi-LAT detection of hard spectrum and highest-level gamma-ray outburst from the distant blazar PKS 1502+106

    NASA Astrophysics Data System (ADS)

    Ciprini, Stefano; Fermi Large Area Telescope Collaboration

    2015-07-01

    The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed flaring gamma rays from a source positionally consistent with the flat spectrum radio quasar PKS 1502+106 (also known as OR 103, S3 1502+10 and 3FGL J1504.4+1029, Acero et al. 2015, ApJS 218, 23), with radio coordinates, (J2000.0), R.A.: 226.10408 deg, Dec: 10.49422 deg (Johnston et al. 1995, AJ, 110, 880). This blazar has a redshift of z=1.8383 (Hewett & Wild 2010, MNRAS, 405, 2302).

  5. Fermi-LAT detection of hard spectrum and high-level gamma-ray flare from the blazar PKS 1954-388

    NASA Astrophysics Data System (ADS)

    Cutini, Sara; Ciprini, Stefano; Fermi Large Area Telescope Collaboration

    2015-09-01

    The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed flaring gamma rays from a source positionally consistent with the flat spectrum radio quasar PKS 1954-388 (also known as MRC 1954-388, RX J1958.0-3845, and 3FGL J1958.0-3847, Acero et al. 2015, ApJS 218, 23), with radio coordinates, (J2000.0), R.A.: 299.499247 deg, Dec.: -38.751766 deg, (Ma et. al. 1998, AJ, 116, 516).

  6. Fermi-LAT Detection of a Hard Spectrum and Enhanced Gamma-ray Emission from the Blazar PMN J2052-5533

    NASA Astrophysics Data System (ADS)

    Carpenter, Bryce; Magill, Jeff; Ojha, Roopesh

    2015-09-01

    The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope has observed an unusually hard spectrum gamma-ray flare from a source positionally consistent with the blazar PMN J2052-5533 (3FGL J2051.8-5535; Acero et al. 2015, ApJS 218, 23), with coordinates RA: 20h52m13.68s, Dec: -55d33m10.0s, J2000, (Healey et al. 2007, ApJS, 171, 61). There is no redshift reported for this source in the literature.

  7. [The spectrum characteristic analysis of mammoth ivory].

    PubMed

    Yin, Zuo-wei; Luo, Qin-feng; Zheng, Chen; Bao, De-qing; Li, Xiao-lu; Li, Yu-ling; Chen, Quan-li

    2013-09-01

    Due to the similarities between mammoth ivory ornaments and modern elephant ivory ones in the market, the spectral properties of the two kinds of ivories were analyzed and compared in the present paper through the gemological tests, infrared spectrum and X-ray powder diffraction, etc. The research found that the refractive index and specific gravity of the two ivories are very similar. The refractive index of mammoth ivory is 1.52-1.53 whereas that of elephant ivory is 1.54-1.55. The specific gravity of mammoth ivory is 1.77 and that of elephant ivory is 1.72. It should be careful that Schreger angles are used to distinguish the two kinds of ivories, because the angles of inner and middle layers in the two kinds of tusks are similar except the angles of elephant tusk out-layers are larger than those of mammoth (The Schreger angle of the sample mammoth ivory belonging to out-layer tusks is 100 degrees nd that of elephant ivory is 115 degrees). In addition, the out-layer Schreger angles of Asian elephants are normally less than 120 degrees, while those of Africa elephants are bigger than 120 degrees (This can be used to identify Asian and Africa elephant ivories). The infrared spectroscopy test shows that the water-molecule-related absorption peaks of 3319, 1642 and 1557 cm(-1) are more obvious in the modern elephant ivory samples than in the mammoth ivory samples; the collagen-related absorption peaks of 2927and 2855 cm(-1) are obvious in the modern elephant ivory but extremely weak in the mammoth ivory. The results indicate that collagen and crystallized water in mammoth ivory reduced to a very low level after having been buried for a long period. X-ray powder diffraction results show that the diffraction peak splits of mammoth ivories are more obvious and sharp than that of elephant ivories, which means hydroxyapatites crystallized better despite being buried for thousands of years. Hence, it is an important reference for identifying the two kinds of ivories that

  8. Evidence for Enhanced 3He in Flare-accelerated Particles Based on New Calculations of the Gamma-Ray Line Spectrum

    NASA Astrophysics Data System (ADS)

    Murphy, R. J.; Kozlovsky, B.; Share, G. H.

    2016-12-01

    The 3He abundance in impulsive solar energetic particle (SEP) events is enhanced up to several orders of magnitude compared to its photospheric value of [3He]/[4He] = 1-3 × 10-4. Interplanetary magnetic field and timing observations suggest that these events are related to solar flares. Observations of 3He in flare-accelerated ions would clarify the relationship between these two phenomena. Energetic 3He 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 3He. Gamma-ray spectroscopy can, therefore, reveal enhanced levels of accelerated 3He. In this paper, we identify all significant deexcitation lines produced by 3He interactions in the solar atmosphere. We evaluate their production cross sections and incorporate them into our nuclear deexcitation-line code. We find that enhanced 3He can affect the entire gamma-ray spectrum. We identify gamma-ray line features for which the yield ratios depend dramatically on the 3He abundance. We determine the accelerated 3He/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 3He, confirming earlier suggestions. The 3He/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 × 10-3 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 3He-rich SEPs.

  9. Hardening anisotropy of {gamma}/{gamma}{prime} superalloy single crystals. 2: Numerical analysis of heterogeneity effects

    SciTech Connect

    Estevez, R.; Hoinard, G.; Franciosi, P.

    1997-04-01

    In the first part of this study, the {gamma}/{gamma}{prime} superalloy single crystals yield stress and hardening anisotropy were experimentally estimated at 650 C, assuming homogeneous plasticity, G. Hoinard, R. Estevez and P. Franciosi, Acta Metall. 43, 1593 (1995). Here alloy morphology is regarded in two different ways: first as a two-phase anisotropic material with a uniform {gamma} matrix, describing the {gamma}{prime} precipitates arrangement with the help of an elementary pattern of inclusions; then treating the {gamma} matrix as a three (geometrical) phase medium, i.e., the three families of orthogonal {gamma} layers separating the precipitates, to estimate the matrix behavior heterogeneity in a 4-phase modelling of the alloy. Both {gamma} and {gamma}{prime} phases are treated as elastic-plastic crystalline media deforming by octahedral and cubic slip, and the models are based on the self consistent approximation. The alloy elasticity limit, internal stresses and hardening anisotropy are discussed with regard to the chosen behavior description for each phase, and behavior simulations are compared to experimental information.

  10. Observation of parity nonconservation in the integrated. gamma. spectrum from (n,. gamma. ) reactions in Cl, Br, Cd, Sn, and La nuclei

    SciTech Connect

    Vesna, V.A.; Kolomenskii, E.A.; Lobashev, V.M.; Nazarenko, V.A.; Pirozhkov, A.N.; Smotritskii, L.M.; Sobolev, Y.V.; Titov, N.A.

    1982-09-05

    A P-odd asymmetry has been observed in the emission of ..gamma.. rays upon the capture of polarized thermal neutrons by Cl, Br, and La nuclei. A circular polarization of the ..gamma.. rays has been observed during the capture of unpolarized neutrons by Cl, Br, Sn, and La nuclei.

  11. Discerning the Gamma-Ray-emitting Region in the Flat Spectrum Radio Quasars

    NASA Astrophysics Data System (ADS)

    Zheng, Y. G.; Yang, C. Y.; Zhang, L.; Wang, J. C.

    2017-01-01

    A model-dependent method is proposed to determine the location of the γ-ray-emitting region for a given flat spectrum radio quasar (FSRQ). In the model, the extra-relativistic electrons are injected at the base of the jet and non-thermal photons are produced by both synchrotron radiation and inverse-Compton (IC) scattering in the energy dissipation region. The target photons dominating IC scattering originate from both synchrotron photons and external ambient photon fields, and the energy density of external radiation field is a function of the distance between the position of the dissipation region and a central supermassive black hole, and their spectra are seen in the comoving frame. Moreover, the energy dissipation region could be determined by the model parameter through reproducing the γ-ray spectra. Such a model is applied to reproduce the quasi-simultaneous multi-wavelength observed data for 36 FSRQs. In order to define the width of the broad-line region (BLR) shell and dusty molecular torus (MT) shell, a simple numerical constraint is used to determine the outer boundary of the BLR and dusty MT. Our results show that (1) the γ-ray-emitting regions are located at the range from 0.1 to 10 pc; (2) the γ-ray-emitting regions are located outside the BLRs and within the dusty molecular tori; and (3) the γ-ray-emitting regions are located closer to the dusty MT ranges than the BLRs. Therefore, it may be concluded that direct evidence for the far site scenario could be obtained on the basis of the model results.

  12. Qualification study of LiF flight crystals for the Objective Crystal Spectrometer on the SPECTRUM-X-GAMMA satellite

    NASA Astrophysics Data System (ADS)

    Christensen, F. E.; Rasmussen, I.; Schnopper, H. W.; Wiebicke, H.; Halm, I.; Geppert, U.; Borozdin, K.

    1992-10-01

    The Objective Crystal Spectrometer (OXS) on the SPECTRUM-X-GAMMA satellite will carry three types of natural crystals LiF(220), Ge(111) and RAP(001). They will be used to study, among others, the H- and the He-like emission from the cosmically important elements Fe, S, Ar and O. More than 300 LiF-crystals of dimension about 23 x 63 sq mm are required to cover one side of a large (about 1000 x 600 sq mm) panel which is to be mounted in front of one of the high throughput X-ray telescopes. A qualification study examined a large sample of LiF(220) crystals at Cu-K-(alpha)2 (8.0278 keV). Data from 124 flight crystals yields an average FWHM of rocking curves of 2.3 arcmin with a standard deviation of 0.4 arcmin. For more than 80 percent of the crystals, angular deviation of the (220) planes from the actual crystal surface is less than 1.5 arcmin. These data will be used to select the best crystals for the flight panel and will determine precisely the orientation of the crystals mounted on the OXS. Eight crystals were glued onto a small test panel of the OXS and for only one crystal was there measured a significant deviation of the crystal properties, including alignment relative to the others.

  13. Development of Mirror Modules for the ART-XC Instrument aboard the Spectrum-Roentgen-Gamma Mission

    NASA Technical Reports Server (NTRS)

    Gubarev, M; Ramsey, B.; O'Dell, S. L.; Elsner, R.; Kilaru, K.; McCracken, J.; Pavlinsky, M.; Tkachenko, A.; Lapshov, I.; Atkins, C.; Zavlin, V.

    2013-01-01

    The Marshall Space Flight Center (MSFC) is developing x-ray mirror modules for the ART-XC instrument on board the Spectrum-Roentgen Gamma Mission. Four of those modules are being fabricated under a Reimbursable Agreement between NASA and the Russian Space Research Institute (IKI.) An additional three flight modules and one spare for the ART-XC Instrument are produced under a Cooperative Agreement between NASA and IKI. The instrument will consist of seven co-aligned x-ray mirror modules with seven corresponding CdTe focal plane detectors. Each module consists of 28 nested thin Ni/Co shells giving an effective area of 65 cm2 at 8 keV, response out to 30 keV, and an angular resolution of 45 arcsec or better HPD. Delivery of the first four modules is scheduled for November 2013, while the remaining three modules will be delivered to IKI in January 2014. We present a status of the ART x-ray module development at MSFC.

  14. Gamma-Ray background spectrum and annihilation rate in the baryon-symmetric big-bang cosmology

    NASA Technical Reports Server (NTRS)

    Puget, J. L.

    1973-01-01

    An attempt was made to extract experimental data on baryon symmetry by observing annihilation products. Specifically, gamma rays and neutrons with long mean free paths were analyzed. Data cover absorption cross sections and radiation background of the 0.511 MeV gamma rays from positron annihilations and the 70 MeV gamma rays from neutral pion decay.

  15. Gamma-Ray background spectrum and annihilation rate in the baryon-symmetric big-bang cosmology

    NASA Technical Reports Server (NTRS)

    Puget, J. L.

    1973-01-01

    An attempt was made to extract experimental data on baryon symmetry by observing annihilation products. Specifically, gamma rays and neutrons with long mean free paths were analyzed. Data cover absorption cross sections and radiation background of the 0.511 MeV gamma rays from positron annihilations and the 70 MeV gamma rays from neutral pion decay.

  16. Spectrum Gamma Ray bore hole logging while tripping with the sea floor drill rig MARUM-MeBo

    NASA Astrophysics Data System (ADS)

    Freudenthal, Tim; Steinke, Stephan; Mohtadi, Mahyar; Hebbeln, Dierk; Wefer, Gerold

    2013-04-01

    The robotic Sea Floor Drill Rig MARUM-MeBo developed at the MARUM Center for Marine Environmental Sciences at the University of Bremen was used to retrieve long sediment cores at two sites in the northern South China Sea. Both sites are located in about 1000 m water depth in southeasterly and southwesterly direction of the Pearl River mouth, respectively. South East Asian Monsoon variability controls terrigenous material transport by rivers into the South China Sea. The Pearl River is one of the largest rivers of the region that discharges into the northern South China Sea. The terrigenous fraction of marine sediments of the northern South China Sea therefore provides an excellent archive for reconstructing past variability of the South East Asian Monsoon system. In analogy to the drilling strategy within the Integrated Ocean Drilling Program IODP multiple holes were drilled in order to generate continuous spliced records at both sites. Overall the MARUM-MeBo drilled 374 m during 5 deployments with a maximum drilling depth of 80.85 m and an average core recovery of 94 %. Here we present first results of bore hole logging conducted during 4 of the 5 deployments with a spectrum gamma ray (SGR) probe adapted for the use with MARUM-MeBo. This probe is an autonomous slim hole probe that is used in the logging while tripping mode. This method is especially favorable for remote controlled drilling and logging operation. The probe is equipped with its own energy source and data storage. The probe is lowered into the drill string after the target wire-line coring depth is reached and after the last inner core barrel has been retrieved. When the probe has landed on the shoulder ring at the bottom of the hole, the drill string is pulled out and disassembled. The probe, while being raised with the drill string, continuously measures the geophysical properties of the in situ sediments and rocks. Since the bore hole is stabilized during the tripping process by the drill string

  17. Power spectrum analysis of astronomical photographs digitised with small apertures.

    NASA Astrophysics Data System (ADS)

    Stobie, R. S.; Okamura, S.; Davenhall, A. C.; MacGillivray, H. T.

    A total of 8 UK Schmidt Telescope plates, 2 Anglo-Australian Telescope prime focus plates and 2 Palomar Observatory Sky Survey (POSS) copies were measured with a scanning aperture of 11 μm and a pixel spacing of 16 μm. Power spectrum analysis of the resulting data shows the plate noise (with the exception of the POSS plates) to correspond to almost white noise over the frequency range 0.1 - 60 cycles mm-1. The signal-to-noise power spectrum is shown to be a useful tool for measuring the information content of an astronomical photograph. A comparison was made of the information content of a survey quality UKST IIIaJ plate and atlas quality copies on very fine-grained emulsion. Power spectrum analysis of exactly the same area on the original plate and copies showed no significant degradation in either emulsion noise or image content of the copy relative to the original.

  18. Spectrum analysis on quality requirements consideration in software design documents.

    PubMed

    Kaiya, Haruhiko; Umemura, Masahiro; Ogata, Shinpei; Kaijiri, Kenji

    2013-12-01

    Software quality requirements defined in the requirements analysis stage should be implemented in the final products, such as source codes and system deployment. To guarantee this meta-requirement, quality requirements should be considered in the intermediate stages, such as the design stage or the architectural definition stage. We propose a novel method for checking whether quality requirements are considered in the design stage. In this method, a technique called "spectrum analysis for quality requirements" is applied not only to requirements specifications but also to design documents. The technique enables us to derive the spectrum of a document, and quality requirements considerations in the document are numerically represented in the spectrum. We can thus objectively identify whether the considerations of quality requirements in a requirements document are adapted to its design document. To validate the method, we applied it to commercial software systems with the help of a supporting tool, and we confirmed that the method worked well.

  19. Elemental composition of the lunar surface: Analysis of gamma ray spectroscopy data from Lunar Prospector

    NASA Astrophysics Data System (ADS)

    Prettyman, T. H.; Hagerty, J. J.; Elphic, R. C.; Feldman, W. C.; Lawrence, D. J.; McKinney, G. W.; Vaniman, D. T.

    2006-12-01

    Gamma ray spectroscopy data acquired by Lunar Prospector are used to determine global maps of the elemental composition of the lunar surface. Maps of the abundance of major oxides, MgO, Al2O3, SiO2, CaO, TiO2, and FeO, and trace incompatible elements, K and Th, are presented along with their geochemical interpretation. Linear spectral mixing is used to model the observed gamma ray spectrum for each map pixel. The spectral shape for each elemental constituent is determined by a Monte Carlo radiation transport calculation. Linearization of the mixing model is accomplished by scaling the spectral shapes with lunar surface parameters determined by neutron spectroscopy, including the number density of neutrons slowing down within the surface and the effective atomic mass of the surface materials. The association of the highlands with the feldspathic lunar meteorites is used to calibrate the mixing model and to determine backgrounds. A linear least squares approach is used to unmix measured spectra to determine the composition of each map pixel. The present analysis uses new gamma ray production cross sections for neutron interactions, resulting in improved accuracy compared to results previously submitted to the Planetary Data System. Systematic variations in lunar composition determined by the spectral unmixing analysis are compared with the lunar soil sample and meteorite collections. Significant results include improved accuracy for the abundance of Th and K in the highlands; identification of large regions, including western Procellarum, that are not well represented by the sample collection; and the association of relatively high concentrations of Mg with KREEP-rich regions on the lunar nearside, which may have implications for the concept of an early magma ocean.

  20. Nuclear gamma rays from solar flares. [analysis of theory of gamma ray line emission from solar flares

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1973-01-01

    The theory of gamma-ray line emission from solar flares is reviewed and revised. It is shown that the line emissions at 0.5, 2.2, 4.4, and 6.1 MeV are due to positron annihilation, deuterium deexcitation following neutron capture on hydrogen, and the deexcitation of excited states in carbon and oxygen. From the observed relative line intensities it is possible to determine the spectrum of accelerated protons in the flare region. This spectrum is found to be very similar to that of charged particles from the flare observed near earth. The total number of protons at the sun is deduced from the observed absolute line intensities for various interaction models.

  1. A dynamic spectrum analysis solution for the characterization of the UHF spectrum

    NASA Astrophysics Data System (ADS)

    Pooler, Richard K.; Narayanan, Ram M.; Sherbondy, Kelly D.; Martone, Anthony F.; Gallagher, Kyle A.

    2016-05-01

    The Spectral Analysis Solution (SAS), under development, is a multichannel superheterodyne signal analyzer with the intended applications of radio frequency (RF) research, radar verification, and general purpose spectrum sensing, primarily in the ultra-wideband (UWB) range from ultra high frequency (UHF) to the S-band. The SAS features a wideband channel operating from 100 kHz to 1.8 GHz and eight narrowband channels having adjustable instantaneous bandwidths ranging from 1 MHz to 100 MHz. The wideband channel provides a large picture of the RF spectrum while the narrowband channels allow for high resolution, low noise floor, and high spurious free dynamic range (SFDR) capabilities. An adaptive graphic user interface (GUI) has been implemented for the system that actively pulls and processes the system data in real time. This paper outlines the motivation and theory behind the system along with system validation and implementation results.

  2. 2009 Autism Spectrum Disorder Research: Portfolio Analysis Report

    ERIC Educational Resources Information Center

    Interagency Autism Coordinating Committee, 2011

    2011-01-01

    In 2010, the Office of Autism Research Coordination (OARC) and Acclaro Research Solutions, Inc., on behalf of the Interagency Autism Coordinating Committee (IACC), conducted a comprehensive analysis of the 2009 autism spectrum disorder (ASD) research portfolio of major Federal agencies and private organizations. This is the second annual analysis…

  3. FFT-Based Spectrum Analysis Using a Digital Signal Processor

    DTIC Science & Technology

    2007-11-02

    Thesis Advisor: Herschel H. Loomis, Jr. Second Reader: Jon Butler Approved for public release; distribution is unlimited. Report Documentation Page...Guide, Texas Instruments, 1999. 8. Gardner, William A., Statistical Spectrum Analysis, Prentice-Hall, 1988. 9. Gutman, Ron. “Algorithm Alley,” Dr...California 3. Loomis, Herschel H., Code EC/Lm. . . . . . . . . . . . . . . . . . . . . . 1 Naval Postgraduate School Monterey, California 4. Butler

  4. Analysis of the Absorption Spectrum of Ruby at High Pressures

    DTIC Science & Technology

    1988-12-01

    8217- Analysis of the absorption spectrum of ruby at high pressures Surinder M. Sharma and Y.M. Gupta Shock Dynamics Laboratory Department of Physics...Elements de Transition et des Elements Lourds Daus Les Solides, Lyon, France, p. 51 (1976). 20. Surinder M. Sharma and Y.M. Gupta, Appl. Phys. Lett. 54, 84

  5. Gamma self-shielding correction factors calculation for aqueous bulk sample analysis by PGNAA technique.

    PubMed

    Nasrabadi, M N; Mohammadi, A; Jalali, M

    2009-01-01

    In this paper bulk sample prompt gamma neutron activation analysis (BSPGNAA) was applied to aqueous sample analysis using a relative method. For elemental analysis of an unknown bulk sample, gamma self-shielding coefficient was required. Gamma self-shielding coefficient of unknown samples was estimated by an experimental method and also by MCNP code calculation. The proposed methodology can be used for the determination of the elemental concentration of unknown aqueous samples by BSPGNAA where knowledge of the gamma self-shielding within the sample volume is required.

  6. Monte Carlo investigation and optimization of coincidence prompt gamma-ray neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Wang, Jiaxin; Calderon, Adan; Peeples, Cody R.; Ai, Xianyun; Gardner, Robin P.

    2011-10-01

    Normal Prompt Gamma-Ray Neutron Activation Analysis (PGNAA) suffers from a large inherent noise or background. The coincidence PGNAA approach is being investigated for eliminating almost all of the interfering backgrounds and thereby significantly improving the signal-to-noise ratio (SNR). This can be done since almost all of the prompt gamma rays from elements of interest are emitted in coincidence except hydrogen. However, it has been found previously that while the use of two normal NaI detectors greatly reduces the background, the signal is also greatly reduced so that very little improvement in standard deviation is obtained. With the help of MCNP5, the general-purpose Monte Carlo N-Particle code, and CEARCPG, the specific purpose Monte Carlo code for Coincidence PGNAA, further optimization of the proposed coincidence system is being accomplished. The idea pursued here is the use of a large area plastic scintillation detector as the trigger for coincidence events together with a normal large NaI detector. In this approach the detection solid angle is increased greatly, which directly increases the probability of coincidence detection. The 2D-coincidence spectrum obtained can then be projected to the axis representing the NaI detector to overcome the drawback of low energy resolution and photopeak intensity of the plastic scintillation detector and utilize the overall higher coincidence counting rate. To reach the best coincidence detection, the placement of detectors, sample, and the moderator of the neutron source have been optimized through Monte Carlo simulation.

  7. [EMD Time-Frequency Analysis of Raman Spectrum and NIR].

    PubMed

    Zhao, Xiao-yu; Fang, Yi-ming; Tan, Feng; Tong, Liang; Zhai, Zhe

    2016-02-01

    This paper analyzes the Raman spectrum and Near Infrared Spectrum (NIR) with time-frequency method. The empirical mode decomposition spectrum becomes intrinsic mode functions, which the proportion calculation reveals the Raman spectral energy is uniform distributed in each component, while the NIR's low order intrinsic mode functions only undertakes fewer primary spectroscopic effective information. Both the real spectrum and numerical experiments show that the empirical mode decomposition (EMD) regard Raman spectrum as the amplitude-modulated signal, which possessed with high frequency adsorption property; and EMD regards NIR as the frequency-modulated signal, which could be preferably realized high frequency narrow-band demodulation during first-order intrinsic mode functions. The first-order intrinsic mode functions Hilbert transform reveals that during the period of empirical mode decomposes Raman spectrum, modal aliasing happened. Through further analysis of corn leaf's NIR in time-frequency domain, after EMD, the first and second orders components of low energy are cut off, and reconstruct spectral signal by using the remaining intrinsic mode functions, the root-mean-square error is 1.001 1, and the correlation coefficient is 0.981 3, both of these two indexes indicated higher accuracy in re-construction; the decomposition trend term indicates the absorbency is ascending along with the decreasing to wave length in the near-infrared light wave band; and the Hilbert transform of characteristic modal component displays, 657 cm⁻¹ is the specific frequency by the corn leaf stress spectrum, which could be regarded as characteristic frequency for identification.

  8. Advanced concepts for gamma-ray isotopic analysis and instrumentation

    SciTech Connect

    Buckley, W.M.; Carlson, J.B.

    1994-07-01

    The Safeguards Technology Program at the Lawrence Livermore National Laboratory is developing actinide isotopic analysis technologies in response to needs that address issues of flexibility of analysis, robustness of analysis, ease-of-use, automation and portability. Recent developments such as the Intelligent Actinide Analysis System (IAAS), begin to address these issues. We are continuing to develop enhancements on this and other instruments that improve ease-of-use, automation and portability. Requests to analyze samples with unusual isotopics, contamination, or containers have made us aware of the need for more flexible and robust analysis. We have modified the MGA program to extend its plutonium isotopic analysis capability to samples with greater {sup 241}Am content or U isotopics. We are looking at methods for dealing with tantalum or lead contamination and contamination with high-energy gamma emitters, such as {sup 233}U. We are looking at ways to allow the program to use additional information about the sample to further extend the domain of analyzable samples. These unusual analyses will come from the domain of samples that need to be measured because of complex reconfiguration or environmental cleanup.

  9. Passive gamma analysis of the boiling-water-reactor assemblies

    SciTech Connect

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

    2016-09-01

    This research focused on the analysis of a set of stationary passive gamma measurements taken on the spent nuclear fuel assemblies from a boiling water reactor (BWR) using pulse height analysis data acquisition. The measurements were performed on 25 different BWR assemblies in 2014 at Sweden’s Central Interim Storage Facility for Spent Nuclear Fuel (Clab). This study was performed as part of the Next Generation of Safeguards Initiative–Spent Fuel project to research the application of nondestructive assay (NDA) to spent fuel assemblies. The NGSI–SF team is working to achieve the following technical goals more easily and efficiently than in the past using nondestructive assay (NDA) 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. The final objective of this project is to quantify the capability of several integrated NDA instruments to meet the aforementioned goals using the combined signatures of neutrons, gamma rays, and heat. This report presents a selection of the measured data and summarizes an analysis of the results. Specifically, trends in the count rates measured for spectral lines from the following isotopes were analyzed as a function of the declared burnup and cooling time: 137Cs, 154Eu, 134Cs, and to a lesser extent, 106Ru and 144Ce. From these measured count rates, predictive algorithms were developed to enable the estimation of the burnup and cooling time. Furthermore, these algorithms were benchmarked on a set of assemblies not included in the standard assemblies set used by this research team.

  10. Passive gamma analysis of the boiling-water-reactor assemblies

    DOE PAGES

    Vo, D.; Favalli, A.; Grogan, B.; ...

    2016-09-01

    This research focused on the analysis of a set of stationary passive gamma measurements taken on the spent nuclear fuel assemblies from a boiling water reactor (BWR) using pulse height analysis data acquisition. The measurements were performed on 25 different BWR assemblies in 2014 at Sweden’s Central Interim Storage Facility for Spent Nuclear Fuel (Clab). This study was performed as part of the Next Generation of Safeguards Initiative–Spent Fuel project to research the application of nondestructive assay (NDA) to spent fuel assemblies. The NGSI–SF team is working to achieve the following technical goals more easily and efficiently than in themore » past using nondestructive assay (NDA) 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. The final objective of this project is to quantify the capability of several integrated NDA instruments to meet the aforementioned goals using the combined signatures of neutrons, gamma rays, and heat. This report presents a selection of the measured data and summarizes an analysis of the results. Specifically, trends in the count rates measured for spectral lines from the following isotopes were analyzed as a function of the declared burnup and cooling time: 137Cs, 154Eu, 134Cs, and to a lesser extent, 106Ru and 144Ce. From these measured count rates, predictive algorithms were developed to enable the estimation of the burnup and cooling time. Furthermore, these algorithms were benchmarked on a set of assemblies not included in the standard assemblies set used by this research team.« less

  11. Passive gamma analysis of the boiling-water-reactor assemblies

    SciTech Connect

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

    2016-09-01

    This research focused on the analysis of a set of stationary passive gamma measurements taken on the spent nuclear fuel assemblies from a boiling water reactor (BWR) using pulse height analysis data acquisition. The measurements were performed on 25 different BWR assemblies in 2014 at Sweden’s Central Interim Storage Facility for Spent Nuclear Fuel (Clab). This study was performed as part of the Next Generation of Safeguards Initiative–Spent Fuel project to research the application of nondestructive assay (NDA) to spent fuel assemblies. The NGSI–SF team is working to achieve the following technical goals more easily and efficiently than in the past using nondestructive assay (NDA) 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. The final objective of this project is to quantify the capability of several integrated NDA instruments to meet the aforementioned goals using the combined signatures of neutrons, gamma rays, and heat. This report presents a selection of the measured data and summarizes an analysis of the results. Specifically, trends in the count rates measured for spectral lines from the following isotopes were analyzed as a function of the declared burnup and cooling time: 137Cs, 154Eu, 134Cs, and to a lesser extent, 106Ru and 144Ce. From these measured count rates, predictive algorithms were developed to enable the estimation of the burnup and cooling time. Furthermore, these algorithms were benchmarked on a set of assemblies not included in the standard assemblies set used by this research team.

  12. Passive gamma analysis of the boiling-water-reactor assemblies

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    This research focused on the analysis of a set of stationary passive gamma measurements taken on the spent nuclear fuel assemblies from a boiling water reactor (BWR) using pulse height analysis data acquisition. The measurements were performed on 25 different BWR assemblies in 2014 at Sweden's Central Interim Storage Facility for Spent Nuclear Fuel (Clab). This study was performed as part of the Next Generation of Safeguards Initiative-Spent Fuel project to research the application of nondestructive assay (NDA) to spent fuel assemblies. The NGSI-SF team is working to achieve the following technical goals more easily and efficiently than in the past using nondestructive assay (NDA) 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. The final objective of this project is to quantify the capability of several integrated NDA instruments to meet the aforementioned goals using the combined signatures of neutrons, gamma rays, and heat. This report presents a selection of the measured data and summarizes an analysis of the results. Specifically, trends in the count rates measured for spectral lines from the following isotopes were analyzed as a function of the declared burnup and cooling time: 137Cs, 154Eu, 134Cs, and to a lesser extent, 106Ru and 144Ce. From these measured count rates, predictive algorithms were developed to enable the estimation of the burnup and cooling time. Furthermore, these algorithms were benchmarked on a set of assemblies not included in the standard assemblies set used by this research team.

  13. Inferred Cosmic-Ray Spectrum from Fermi-LAT Gamma-Ray Observations of the Earths Limb

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Brandt, T. J.; Hewitt, J.W.; Perkins, J. S.; Thompson, D. J.

    2014-01-01

    Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly-discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the -ray emission from the Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range approx. 90 GeV-6 TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68 +/- 0.04 and 2.61 +/- 0.08 above approx. 200 GeV, respectively.

  14. The Second Catalog of Flaring Gamma-Ray Sources from the Fermi All-sky Variability Analysis

    NASA Astrophysics Data System (ADS)

    Abdollahi, S.; Ackermann, M.; Ajello, M.; Albert, A.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Becerra Gonzalez, J.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonino, R.; Bottacini, E.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Chekhtman, A.; Cheung, C. C.; Chiaro, G.; Ciprini, S.; Conrad, J.; Costantin, D.; Costanza, F.; Cutini, S.; D’Ammando, F.; de Palma, F.; Desai, A.; Desiante, R.; Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Donaggio, B.; Drell, P. S.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giomi, M.; Giordano, F.; Giroletti, M.; Glanzman, T.; Green, D.; Grenier, I. A.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hays, E.; Horan, D.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Kocevski, D.; Kuss, M.; La Mura, G.; Larsson, S.; Latronico, L.; Li, J.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Magill, J. D.; Maldera, S.; Manfreda, A.; Mayer, M.; Mazziotta, M. N.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Negro, M.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Paliya, V. S.; Paneque, D.; Perkins, J. S.; Persic, M.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Porter, T. A.; Principe, G.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Stawarz, L.; Suson, D. J.; Takahashi, M.; Tanaka, K.; Thayer, J. B.; Thompson, D. J.; Torres, D. F.; Torresi, E.; Tosti, G.; Troja, E.; Vianello, G.; Wood, K. S.

    2017-09-01

    We present the second catalog of flaring gamma-ray sources (2FAV) detected with the Fermi All-sky Variability Analysis (FAVA), a tool that blindly searches for transients over the entire sky observed by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. With respect to the first FAVA catalog, this catalog benefits from a larger data set, the latest LAT data release (Pass 8), as well as from an improved analysis that includes likelihood techniques for a more precise localization of the transients. Applying this analysis to the first 7.4 years of Fermi observations, and in two separate energy bands 0.1–0.8 GeV and 0.8–300 GeV, a total of 4547 flares were detected with significance greater than 6σ (before trials), on the timescale of one week. Through spatial clustering of these flares, 518 variable gamma-ray sources were identified. Based on positional coincidence, likely counterparts have been found for 441 sources, mostly among the blazar class of active galactic nuclei. For 77 2FAV sources, no likely gamma-ray counterpart has been found. For each source in the catalog, we provide the time, location, and spectrum of each flaring episode. Studying the spectra of the flares, we observe a harder-when-brighter behavior for flares associated with blazars, with the exception of BL Lac flares detected in the low-energy band. The photon indexes of the flares are never significantly smaller than 1.5. For a leptonic model, and under the assumption of isotropy, this limit suggests that the spectrum of freshly accelerated electrons is never harder than p∼ 2.

  15. Understanding Doppler Broadening of Gamma Rays

    SciTech Connect

    Rawool-Sullivan, Mohini; Sullivan, John P.

    2014-07-03

    Doppler-broadened gamma ray peaks are observed routinely in the collection and analysis of gamma-ray spectra. If not recognized and understood, the appearance of Doppler broadening can complicate the interpretation of a spectrum and the correct identification of the gamma ray-emitting material. We have conducted a study using a simulation code to demonstrate how Doppler broadening arises and provide a real-world example in which Doppler broadening is found. This report describes that study and its results.

  16. Condensing Raman spectrum for single-cell phenotype analysis.

    PubMed

    Sun, Shiwei; Wang, Xuetao; Gao, Xin; Ren, Lihui; Su, Xiaoquan; Bu, Dongbo; Ning, Kang

    2015-01-01

    In recent years, high throughput and non-invasive Raman spectrometry technique has matured as an effective approach to identification of individual cells by species, even in complex, mixed populations. Raman profiling is an appealing optical microscopic method to achieve this. To fully utilize Raman proling for single-cell analysis, an extensive understanding of Raman spectra is necessary to answer questions such as which filtering methodologies are effective for pre-processing of Raman spectra, what strains can be distinguished by Raman spectra, and what features serve best as Raman-based biomarkers for single-cells, etc. In this work, we have proposed an approach called rDisc to discretize the original Raman spectrum into only a few (usually less than 20) representative peaks (Raman shifts). The approach has advantages in removing noises, and condensing the original spectrum. In particular, effective signal processing procedures were designed to eliminate noise, utilising wavelet transform denoising, baseline correction, and signal normalization. In the discretizing process, representative peaks were selected to signicantly decrease the Raman data size. More importantly, the selected peaks are chosen as suitable to serve as key biological markers to differentiate species and other cellular features. Additionally, the classication performance of discretized spectra was found to be comparable to full spectrum having more than 1000 Raman shifts. Overall, the discretized spectrum needs about 5storage space of a full spectrum and the processing speed is considerably faster. This makes rDisc clearly superior to other methods for single-cell classication.

  17. Isotopic ratio of 129I/127I in seaweed measured by neutron activation analysis with gamma-gamma coincidence.

    PubMed

    Toh, Y; Hatsukawa, Y; Oshima, M; Shinohara, N; Hayakawa, T; Kushita, K; Ueno, T

    2002-07-01

    129I is a long-lived (1.6 x 10(7) y) radionuclide that is produced in nature as the result of spontaneous fission of heavy elements and reaction of xenon with cosmic rays. Recently, however, artificial sources from nuclear power plants and nuclear test explosions have become a significant component of environmental radioactive iodine. Coincidence gamma-ray detection using Ge detectors makes it possible to simultaneously resolve the numerous gamma-rays produced by neutron activation. In this study, the coincidence gamma-ray detection technique was combined with neutron activation analysis to determine the radioactive iodine composition of seaweed. The ratio of 129I/127I in this common Japanese food item collected from the Ibaraki prefecture has been derived without the need for radiochemical purification. The isotopic ratio of 129I/127I in Kajime algae is 3.5(5) x 10(-10).

  18. Spectral mixture analysis of EELS spectrum-images.

    PubMed

    Dobigeon, Nicolas; Brun, Nathalie

    2012-09-01

    Recent advances in detectors and computer science have enabled the acquisition and the processing of multidimensional datasets, in particular in the field of spectral imaging. Benefiting from these new developments, Earth scientists try to recover the reflectance spectra of macroscopic materials (e.g., water, grass, mineral types…) present in an observed scene and to estimate their respective proportions in each mixed pixel of the acquired image. This task is usually referred to as spectral mixture analysis or spectral unmixing (SU). SU aims at decomposing the measured pixel spectrum into a collection of constituent spectra, called endmembers, and a set of corresponding fractions (abundances) that indicate the proportion of each endmember present in the pixel. Similarly, when processing spectrum-images, microscopists usually try to map elemental, physical and chemical state information of a given material. This paper reports how a SU algorithm dedicated to remote sensing hyperspectral images can be successfully applied to analyze spectrum-image resulting from electron energy-loss spectroscopy (EELS). SU generally overcomes standard limitations inherent to other multivariate statistical analysis methods, such as principal component analysis (PCA) or independent component analysis (ICA), that have been previously used to analyze EELS maps. Indeed, ICA and PCA may perform poorly for linear spectral mixture analysis due to the strong dependence between the abundances of the different materials. One example is presented here to demonstrate the potential of this technique for EELS analysis. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Prompt Gamma Activation Analysis (PGAA): Technique of choice for nondestructive bulk analysis of returned comet samples

    NASA Technical Reports Server (NTRS)

    Lindstrom, David J.; Lindstrom, Richard M.

    1989-01-01

    Prompt gamma activation analysis (PGAA) is a well-developed analytical technique. The technique involves irradiation of samples in an external neutron beam from a nuclear reactor, with simultaneous counting of gamma rays produced in the sample by neutron capture. Capture of neutrons leads to excited nuclei which decay immediately with the emission of energetic gamma rays to the ground state. PGAA has several advantages over other techniques for the analysis of cometary materials: (1) It is nondestructive; (2) It can be used to determine abundances of a wide variety of elements, including most major and minor elements (Na, Mg, Al, Si, P, K, Ca, Ti, Cr, Mn, Fe, Co, Ni), volatiles (H, C, N, F, Cl, S), and some trace elements (those with high neutron capture cross sections, including B, Cd, Nd, Sm, and Gd); and (3) It is a true bulk analysis technique. Recent developments should improve the technique's sensitivity and accuracy considerably.

  20. The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV

    DOE PAGES

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

    2015-01-19

    We present that the γ-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse γ-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy rangemore » between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission (DGE), and a longer data accumulation of 50 months allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 ± 0.02 and a break energy of (279 ± 52) GeV using our baseline DGE model. In conclusion, the total intensity attributed to the IGRB is (7.2 ± 0.6) × 10–6 cm–2 s–1 sr–1 above 100 MeV, with an additional +15%/–30% systematic uncertainty due to the Galactic diffuse foregrounds.« less

  1. The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV

    SciTech Connect

    Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cuoco, A.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Digel, S. W.; do Couto e Silva, E.; Drell, P. S.; Favuzzi, C.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hayashi, K.; Hays, E.; Hewitt, J. W.; Ippoliti, P.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Manfreda, A.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Romani, R. W.; Sánchez-Conde, M.; Schaal, M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vianello, G.; Werner, M.; Winer, B. L.; Wood, K. S.; Wood, M.; Zaharijas, G.; Zimmer, S.

    2015-01-19

    We present that the γ-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse γ-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission (DGE), and a longer data accumulation of 50 months allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 ± 0.02 and a break energy of (279 ± 52) GeV using our baseline DGE model. In conclusion, the total intensity attributed to the IGRB is (7.2 ± 0.6) × 10–6 cm–2 s–1 sr–1 above 100 MeV, with an additional +15%/–30% systematic uncertainty due to the Galactic diffuse foregrounds.

  2. The Spectrum of Isotropic Diffuse Gamma-Ray Emission between 100 MeV and 820 GeV

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bottacini, E.; Brandt, T. J.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cuoco, A.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Favuzzi, C.; Ferrara, E. C.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Godfrey, G.; Gomez-Vargas, G. A.; Grenier, I. A.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hayashi, K.; Hays, E.; Hewitt, J. W.; Ippoliti, P.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Madejski, G. M.; Manfreda, A.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Romani, R. W.; Sánchez-Conde, M.; Schaal, M.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Strong, A. W.; Suson, D. J.; Takahashi, H.; Thayer, J. G.; Thayer, J. B.; Tibaldo, L.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vianello, G.; Werner, M.; Winer, B. L.; Wood, K. S.; Wood, M.; Zaharijas, G.; Zimmer, S.

    2015-01-01

    The γ-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse γ-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission (DGE), and a longer data accumulation of 50 months allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 ± 0.02 and a break energy of (279 ± 52) GeV using our baseline DGE model. The total intensity attributed to the IGRB is (7.2 ± 0.6) × 10-6 cm-2 s-1 sr-1 above 100 MeV, with an additional +15%/-30% systematic uncertainty due to the Galactic diffuse foregrounds.

  3. Towards new analysis of Gamma-Ray sources at HImalayan Gamma-Ray Observatory (HIGRO) in northern India

    NASA Astrophysics Data System (ADS)

    Britto, R. J.; Acharya, B. S.; Anupama, G. C.; Bhatt, N.; Bhattacharjee, P.; Bhattacharya, S.; Chitnis, V. R.; Cowsik, R.; Dorji, N.; Duhan, S. K.; Gothe, K. S.; Kamath, P. U.; Koul, R.; Mahesh, P. K.; Mitra, A.; Nagesh, B. K.; Parmar, N. K.; Prabhu, T. P.; Rannot, R. C.; Rao, S. K.; Saha, L.; Saleem, F.; Saxena, A. K.; Sharma, S. K.; Shukla, A.; Singh, B. B.; Srinivasan, R.; Srinivasulu, G.; Sudersanan, P. V.; Tickoo, A. K.; Tsewang, D.; Upadhya, S. S.; Vishwanath, P. R.; Yadav, K. K.

    2010-12-01

    The High Altitude GAmma-Ray (HAGAR) array is a wavefront sampling array of 7 telescopes, set-up at Hanle, at 4270 m a.s.l., in the Ladakh region of the Himalayas (North India). It constitutes the first phase of the HImalayan Gamma-Ray Observatory (HIGRO) project. HAGAR is the first array of atmospheric Cherenkov telescopes established at a so high altitude, and was designed to reach a relatively low threshold (currently around 200 GeV) with quite a low mirror area (31 m^2). Data are acquired using the On-source/Off-source tracking mode, and by comparing these sky regions the strength of the gamma-ray signal is estimated. Regular source observations are running since Sept. 2008 and preliminary results on Crab nebula were reported by 2009. Improvements of our analysis method are still going on, like estimation of arrival direction and estimation of night sky background. New softwares are under development for analysis of flash ADC modules, which provide more information from the incoming Cherenkov light wavefront. We report and discuss our new estimation of the systematics through dark region studies, and present new perspectives in the analysis of gamma-ray sources in this paper.

  4. Monte Carlo simulation of a PhosWatch detector using Geant4 for xenon isotope beta-gamma coincidence spectrum profile and detection efficiency calculations.

    PubMed

    Mekarski, P; Zhang, W; Ungar, K; Bean, M; Korpach, E

    2009-10-01

    A simulation tool has been developed using the Geant4 Toolkit to simulate a PhosWatch single channel beta-gamma coincidence detection system consisting of a CsI(Tl)/BC404 Phoswich well detector and pulse shape analysis algorithms implemented digital signal processor. The tool can be used to simulate the detector's response for all the gamma rays and beta particles emitted from (135)Xe, (133m)Xe, (133)Xe, (131m)Xe and (214)Pb. Two- and three-dimensional beta-gamma coincidence spectra from the PhosWatch detector can be produced using the simulation tool. The accurately simulated spectra could be used to calculate system coincidence detection efficiency for each xenon isotope, the corrections for the interference from the various spectral components from radon and xenon isotopes, and system gain calibration. Also, it can generate two- and three-dimensional xenon reference spectra to test beta-gamma coincidence spectral deconvolution analysis software.

  5. Measurements of soil carbon by neutron-gamma analysis in static and scanning modes

    USDA-ARS?s Scientific Manuscript database

    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 detecto...

  6. Spectral saliency via automatic adaptive amplitude spectrum analysis

    NASA Astrophysics Data System (ADS)

    Wang, Xiaodong; Dai, Jialun; Zhu, Yafei; Zheng, Haiyong; Qiao, Xiaoyan

    2016-03-01

    Suppressing nonsalient patterns by smoothing the amplitude spectrum at an appropriate scale has been shown to effectively detect the visual saliency in the frequency domain. Different filter scales are required for different types of salient objects. We observe that the optimal scale for smoothing amplitude spectrum shares a specific relation with the size of the salient region. Based on this observation and the bottom-up saliency detection characterized by spectrum scale-space analysis for natural images, we propose to detect visual saliency, especially with salient objects of different sizes and locations via automatic adaptive amplitude spectrum analysis. We not only provide a new criterion for automatic optimal scale selection but also reserve the saliency maps corresponding to different salient objects with meaningful saliency information by adaptive weighted combination. The performance of quantitative and qualitative comparisons is evaluated by three different kinds of metrics on the four most widely used datasets and one up-to-date large-scale dataset. The experimental results validate that our method outperforms the existing state-of-the-art saliency models for predicting human eye fixations in terms of accuracy and robustness.

  7. New Mexico Play Fairway Analysis: Gamma Ray Logs and Heat Generation Calculations for SW New Mexico

    SciTech Connect

    Shari Kelley

    2015-10-23

    For the New Mexico Play fairway Analysis project, gamma ray geophysical well logs from oil wells penetrating the Proterozoic basement in southwestern New Mexico were digitized. Only the portion of the log in the basement was digitized. The gamma ray logs are converted to heat production using the equation (Bucker and Rybach, 1996) : A[µW/m3] = 0.0158 (Gamma Ray [API] – 0.8).

  8. Galactic plane gamma-radiation

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Fichtel, C. E.; Ogelman, H. B.; Tumer, T.; Ozel, M. E.

    1979-01-01

    Analysis of the SAS 2 data together with the COS B results shows that the distribution of galactic gamma-radiation has several similarities to that of other large-scale tracers of galactic structure. The radiation is primarily confined to a thin disc which exhibits offsets from b = 0 degrees similar to warping at radio frequencies. The principal distinction of the gamma-radiation is a stronger contrast in intensity between the region from 310 to 45 degrees in longitude and the regions away from the center that can be attributed to a variation in cosmic-ray density as a function of position in Galaxy. The diffuse galactic gamma-ray energy spectrum shows no significant variation in direction, and the spectrum seen along the plane is the same as that for the galactic component of the gamma-radiation at high altitudes. The uniformity of the galactic gamma-ray spectrum, the smooth decrease in intensity as a function of altitude, and the absence of any galactic gamma-ray sources at high altitudes indicate a diffuse origin for bulk of the galactic gamma-radiation rather than a collection of localized sources.

  9. A revised analysis of gamma-ray bursts' prompt efficiencies

    NASA Astrophysics Data System (ADS)

    Beniamini, Paz; Nava, Lara; Piran, Tsvi

    2016-09-01

    The prompt gamma-ray bursts' (GRBs) efficiency is an important clue on the emission mechanism producing the γ-rays. Previous estimates of the kinetic energy of the blast waves, based on the X-ray afterglow luminosity LX, suggested that this efficiency is large, with values above 90 per cent in some cases. This poses a problem to emission mechanisms and in particular to the internal shocks model. These estimates are based, however, on the assumption that the X-ray emitting electrons are fast cooling and that their Inverse Compton (IC) losses are negligible. The observed correlations between LX (and hence the blast wave energy) and Eγ, iso, the isotropic equivalent energy in the prompt emission, has been considered as observational evidence supporting this analysis. It is reasonable that the prompt gamma-ray energy and the blast wave kinetic energy are correlated and the observed correlation corroborates, therefore, the notion LX is indeed a valid proxy for the latter. Recent findings suggest that the magnetic field in the afterglow shocks is significantly weaker than was earlier thought and its equipartition fraction, ɛB, could be as low as 10-4 or even lower. Motivated by these findings we reconsider the problem, taking now IC cooling into account. We find that the observed LX - Eγ, iso correlation is recovered also when IC losses are significant. For small ɛB values the blast wave must be more energetic and we find that the corresponding prompt efficiency is significantly smaller than previously thought. For example, for ɛB ˜ 10-4 we infer a typical prompt efficiency of ˜15 per cent.

  10. EGAF: Measurement and Analysis of Gamma-ray Cross Sections

    NASA Astrophysics Data System (ADS)

    Firestone, R. B.; Abusaleem, K.; Basunia, M. S.; Bečvář, F.; Belgya, T.; Bernstein, L. A.; Choi, H. D.; Escher, J. E.; Genreith, C.; Hurst, A. M.; Krtička, M.; Renne, P. R.; Révay, Zs.; Rogers, A. M.; Rossbach, M.; Siem, S.; Sleaford, B.; Summers, N. C.; Szentmiklosi, L.; van Bibber, K.; Wiedeking, M.

    2014-05-01

    The Evaluated Gamma-ray Activation File (EGAF) is the result of a 2000-2007 IAEA Coordinated Research Project to develop a database of thermal, prompt γ-ray cross sections, σγ, for all elemental and selected radioactive targets. No previous database of this kind had existed. EGAF was originally based on measurements using guided neutron beams from the Budapest Reactor on all elemental targets from Z=1-82, 90 and 92, except for He and Pm. The EGAF σγ data were published in the Database of Prompt Gamma Rays from Slow Neutron Capture for Elemental Analysis [1]. An international collaboration has formed to continue the EGAF measurements with isotopically enriched targets, derive total radiative thermal neutron cross sections, σ0, extend the σγ data from thermal to 20 MeV neutrons, compile a completed activation data file, improve sections of the Reference Input Parameter Library (RIPL) with more complete and up to date level and γ-ray data, evaluate statistical γ-ray data from reaction studies, and determine recommended neutron separations energies, Sn, for atomic mass evaluations. A new guided neutron beam facility has become available at the Garching (Munich) FRM II Reactor, and high energy neutron experimental facilities are being developed by a Berkeley area collaboration where 5-33 MeV neutron beams are available at the LBNL 88” cyclotron, 2.5 and 14 MeV beams at the University of California, Berkeley neutron generator laboratory, and high flux, 10 nṡcmṡ-2 s-1, neutron pulses available from the LLNL National Ignition Facility (NIF).

  11. A mass spectroscopic analysis of {gamma}-GPS films

    SciTech Connect

    Dillingham, R.G.; Boerio, F.J.; Bertelsen, C.; Savina, M.R.; Lykke, K.; Calaway, W.

    1996-12-31

    Preparation of substrates for painting or adhesive bonding frequently includes roughening through sanding, chemical etching, or gritblasting. Increased roughness can improve interfacial strength and durability due to increased mechanical interlocking, increased surface area, and improved wettability of the substrate. The chemical reactivity of the surface with the organic phase may be affected as well, perhaps related to the strain energy stored in the surface regions through the intense plastic deformation that occurs. Unfortunately, the chemistry of interactions taking place near a surface that has been roughened is difficult to access analytically by some of the more useful techniques such as infrared spectroscopy. This paper discusses analysis of nonreflective grit-blasted surfaces using mass spectroscopy of species which were either sputtered off using an ion beam (Static Secondary Ion Mass Spectroscopy, or SSIMS) or thermally desorbed as neutrals using a pulsed laser and then post-ionized using a secondary laser (Laser Desorption-Laser Ionization Mass Spectroscopy, or LDLIMS). Both of these techniques exhibit sub-nanometer sensitivity and provide significant information as to the chemistry and structure of the surface regions. In a current application of {gamma}-glycidoxypropyltrimethoxysilane ({gamma}-GPS) for the pre-treatment of grit-blasted aluminum before adhesive bonding, certain factors related to the handling of the primer solution and to the application technique were found to significantly affect the performance of the adhesive bond under long-term aging conditions including stress and humidity. To understand why these parameters are important and to potentially improve the pretreatment process even further, the authors have been investigating how the structure and reactivity of these silane films are related to the application techniques.

  12. Whether the Autism Spectrum Quotient Consists of Two Different Subgroups? Cluster Analysis of the Autism Spectrum Quotient in General Population

    ERIC Educational Resources Information Center

    Kitazoe, Noriko; Fujita, Naofumi; Izumoto, Yuji; Terada, Shin-ichi; Hatakenaka, Yuhei

    2017-01-01

    The purpose of this study was to investigate whether the individuals in the general population with high scores on the Autism Spectrum Quotient constituted a single homogeneous group or not. A cohort of university students (n = 4901) was investigated by cluster analysis based on the original five subscales of the Autism Spectrum Quotient. Based on…

  13. Power spectrum analysis of astronomical photographs digitised with small apertures

    NASA Astrophysics Data System (ADS)

    Stobie, R. S.; Okamura, S.; Davenhall, A. C.; MacGillivray, H. T.

    1984-04-01

    Noise characteristics of images on 8 UK Schmidt Telescope plates, 2 Anglo-Australian Telescope prime focus plates, and 2 Palomar Observatory Sky Survey (POSS) copies (comprising 3 different emulsion types) were measured with a scanning aperture of 11 microns and a pixel spacing of 16 microns. Power spectrum analysis shows plate noise (except POSS plates) to correspond to almost white noise over the frequency range 0.1 to 60 cycles/mm. The signal-to-noise power spectrum is shown to be a useful tool for measuring the information content of an astronomical photograph. Macronoise computed over 8 x 8 mm regions on the plates varies as the minus half power of the aperture area. Information content of a survey quality IIIa-J plate and atlas quality copies on very fine-grained emulsion were compared. Analysis shows no significant degradation in emulsion noise or image content of the copy relative to the original.

  14. Spectral Analysis Of Digital Wave Data Computer Program: SPECTRUM

    DTIC Science & Technology

    1987-06-01

    spectrum and time series analysis may be found in Bendat and Piersol (L97L), Borgman (1972), Borgman (1973), Lund (1986), and Welch (1967). The...Including Procedures Based on the Fast Fourier Transform Algorithm", STL #2008, University of Wyoming, Laramie, WY. Lund , Robert B. "A Mathematical Model...Engineering Research Center, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. Rye, Henrik . 1977. "The Stability of Some Currently Used Wave

  15. Blind Extraction and Security Analysis of Spread Spectrum Hidden Watermarks

    DTIC Science & Technology

    2012-04-01

    DATES COVERED (From - To) JAN 2009 – DEC 2010 4. TITLE AND SUBTITLE BLIND EXTRACTION AND SECURITY ANALYSIS OF SPREAD SPECTRUM HIDDEN WATERMARKS ...Multi Signature Embedding, Watermarking , DSSS. 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 15 19a... watermarks John A. Marsh*a,b, and Gerard F. Wohlrabc aSUNY Institute of Technology, 100 Seymour Dr., Utica, NY 13502; bAssured Information

  16. [Research of Identify Spatial Object Using Spectrum Analysis Technique].

    PubMed

    Song, Wei; Feng, Shi-qi; Shi, Jing; Xu, Rong; Wang, Gong-chang; Li, Bin-yu; Liu, Yu; Li, Shuang; Cao Rui; Cai, Hong-xing; Zhang, Xi-he; Tan, Yong

    2015-06-01

    The high precision scattering spectrum of spatial fragment with the minimum brightness of 4.2 and the resolution of 0.5 nm has been observed using spectrum detection technology on the ground. The obvious differences for different types of objects are obtained by the normalizing and discrete rate analysis of the spectral data. Each of normalized multi-frame scattering spectral line shape for rocket debris is identical. However, that is different for lapsed satellites. The discrete rate of the single frame spectrum of normalized space debris for rocket debris ranges from 0.978% to 3.067%, and the difference of oscillation and average value is small. The discrete rate for lapsed satellites ranges from 3.118 4% to 19.472 7%, and the difference of oscillation and average value relatively large. The reason is that the composition of rocket debris is single, while that of the lapsed satellites is complex. Therefore, the spectrum detection technology on the ground can be used to the classification of the spatial fragment.

  17. Low-Frequency Repetitive Transcranial Magnetic Stimulation (rTMS) Modulates Evoked-Gamma Frequency Oscillations in Autism Spectrum Disorder (ASD)

    PubMed Central

    Baruth, Joshua M.; Casanova, Manuel F.; El-Baz, Ayman; Horrell, Tim; Mathai, Grace; Sears, Lonnie; Sokhadze, Estate

    2010-01-01

    Introduction It has been reported that individuals with Autism Spectrum Disorder (ASD) have abnormal reactions to the sensory environment and visuo-perceptual abnormalities. Electrophysiological research has provided evidence that gamma band activity (30-80 Hz) is a physiological indicator of the co-activation of cortical cells engaged in processing visual stimuli and integrating different features of a stimulus. A number of studies have found augmented and indiscriminative gamma band power at early stages of visual processing in ASD; this may be related to decreased inhibitory processing and an increase in the ratio of cortical excitation to inhibition. Low frequency or ‘slow’ (≤1HZ) repetitive transcranial magnetic stimulation (rTMS) has been shown to increase inhibition of stimulated cortex by the activation of inhibitory circuits. Methods We wanted to test the hypothesis of gamma band abnormalities at early stages of visual processing in ASD by investigating relative evoked (i.e. ~ 100 ms) gamma power in 25 subjects with ASD and 20 age-matched controls using Kanizsa illusory figures. Additionally, we wanted to assess the effects of 12 sessions of bilateral ‘slow’ rTMS to the dorsolateral prefrontal cortex (DLPFC) on evoked gamma activity using a randomized controlled design. Results In individuals with ASD evoked gamma activity was not discriminative of stimulus type, whereas in controls early gamma power differences between target and non-target stimuli were highly significant. Following rTMS individuals with ASD showed significant improvement in discriminatory gamma activity between relevant and irrelevant visual stimuli. We also found significant improvement in the responses on behavioral questionnaires (i.e., irritability, repetitive behavior) as a result of rTMS. Conclusion We proposed that ‘slow’ rTMS may have increased cortical inhibitory tone which improved discriminatory gamma activity at early stages of visual processing. rTMS has the

  18. Spectral analysis of shielded gamma ray sources using precalculated library data

    NASA Astrophysics Data System (ADS)

    Holmes, Thomas Wesley; Gardner, Robin P.

    2015-11-01

    In this work, an approach has been developed for determining the intensity of a shielded source by first determining the thicknesses of three different shielding materials from a passively collected gamma-ray spectrum by making comparisons with predetermined shielded spectra. These evaluations are dependent on the accuracy and validity of the predetermined library spectra which were created by changing the thicknesses of the three chosen materials lead, aluminum and wood that are used to simulate any actual shielding. Each of the spectra produced was generated using MCNP5 with a sufficiently large number of histories to ensure a low relative error at each channel. The materials were held in the same respective order from source to detector, where each material consisted of three individual thicknesses and a null condition. This then produced two separate data sets of 27 total shielding material situations and subsequent predetermined libraries that were created for each radionuclide source used. The technique used to calculate the thicknesses of the materials implements a Levenberg-Marquardt nonlinear search that employs a tri-linear interpolation with the respective predetermined libraries within each channel for the supplied input unknown spectrum. Given that the nonlinear parameters require an initial guess for the calculations, the approach demonstrates first that when the correct values are input, the correct thicknesses are found. It then demonstrates that when multiple trials of random values are input for each of the nonlinear parameters, the average of the calculated solutions that successfully converges also produced the correct thicknesses. Under situations with sufficient information known about the detection situation at hand, the method was shown to behave in a manner that produces reasonable results and can serve as a good preliminary solution. This technique has the capability to be used in a variety of full spectrum inverse analysis problems

  19. Condensing Raman spectrum for single-cell phenotype analysis

    PubMed Central

    2015-01-01

    Background In recent years, high throughput and non-invasive Raman spectrometry technique has matured as an effective approach to identification of individual cells by species, even in complex, mixed populations. Raman profiling is an appealing optical microscopic method to achieve this. To fully utilize Raman proling for single-cell analysis, an extensive understanding of Raman spectra is necessary to answer questions such as which filtering methodologies are effective for pre-processing of Raman spectra, what strains can be distinguished by Raman spectra, and what features serve best as Raman-based biomarkers for single-cells, etc. Results In this work, we have proposed an approach called rDisc to discretize the original Raman spectrum into only a few (usually less than 20) representative peaks (Raman shifts). The approach has advantages in removing noises, and condensing the original spectrum. In particular, effective signal processing procedures were designed to eliminate noise, utilising wavelet transform denoising, baseline correction, and signal normalization. In the discretizing process, representative peaks were selected to signicantly decrease the Raman data size. More importantly, the selected peaks are chosen as suitable to serve as key biological markers to differentiate species and other cellular features. Additionally, the classication performance of discretized spectra was found to be comparable to full spectrum having more than 1000 Raman shifts. Overall, the discretized spectrum needs about 5storage space of a full spectrum and the processing speed is considerably faster. This makes rDisc clearly superior to other methods for single-cell classication. PMID:26681607

  20. Coincidence Prompt Gamma-Ray Neutron Activation Analysis

    SciTech Connect

    R.P. gandner; C.W. Mayo; W.A. Metwally; W. Zhang; W. Guo; A. Shehata

    2002-11-10

    The normal prompt gamma-ray neutron activation analysis for either bulk or small beam samples inherently has a small signal-to-noise (S/N) ratio due primarily to the neutron source being present while the sample signal is being obtained. Coincidence counting offers the possibility of greatly reducing or eliminating the noise generated by the neutron source. The present report presents our results to date on implementing the coincidence counting PGNAA approach. We conclude that coincidence PGNAA yields: (1) a larger signal-to-noise (S/N) ratio, (2) more information (and therefore better accuracy) from essentially the same experiment when sophisticated coincidence electronics are used that can yield singles and coincidences simultaneously, and (3) a reduced (one or two orders of magnitude) signal from essentially the same experiment. In future work we will concentrate on: (1) modifying the existing CEARPGS Monte Carlo code to incorporate coincidence counting, (2) obtaining coincidence schemes for 18 or 20 of the common elements in coal and cement, and (3) optimizing the design of a PGNAA coincidence system for the bulk analysis of coal.

  1. Can the cosmic x ray and gamma ray background be due to reflection of a steep power law spectrum and Compton scattering by relativistic electrons?

    NASA Technical Reports Server (NTRS)

    Zycki, Piotr T.; Zdziarski, Andrzej A.; Svensson, Roland

    1991-01-01

    We reconsider the recent model for the origin in the cosmic X-ray and gamma-ray background by Rogers and Field. The background in the model is due to an unresolved population of AGNs. An individual AGN spectrum contains three components: a power law with the energy index of alpha = 1.1, an enhanced reflection component, and a component from Compton scattering by relativistic electrons with a low energy cutoff at some minimum Lorentz factor, gamma(sub min) much greater than 1. The MeV bump seen in the gamma-ray background is then explained by inverse Compton emission by the electrons. We show that the model does not reproduce the shape of the observed X-ray and gamma-ray background below 10 MeV and that it overproduces the background at larger energies. Furthermore, we find the assumptions made for the Compton component to be physically inconsistent. Relaxing the inconsistent assumptions leads to model spectra even more different from that of the observed cosmic background. Thus, we can reject the hypothesis that the high-energy cosmic background is due to the described model.

  2. SPECTRAL ANALYSIS AND INTERPRETATION OF THE {gamma}-RAY EMISSION FROM THE STARBURST GALAXY NGC 253

    SciTech Connect

    Abramowski, A.; Acero, F.; Akhperjanian, A. G.; Anton, G.; Balzer, A.; Brucker, J.; Barnacka, A.; Becherini, Y.; Birsin, E.; Biteau, J.; Brun, F.; Bolmont, J.; Brun, P.; Collaboration: H.E.S.S. Collaboration; and others

    2012-10-01

    Very high energy (VHE; E {>=} 100 GeV) and high-energy (HE; 100 MeV {<=} E {<=} 100 GeV) data from {gamma}-ray observations performed with the H.E.S.S. telescope array and the Fermi-LAT instrument, respectively, are analyzed in order to investigate the non-thermal processes in the starburst galaxy NGC 253. The VHE {gamma}-ray data can be described by a power law in energy with differential photon index {Gamma} = 2.14 {+-} 0.18{sub stat} {+-} 0.30{sub sys} and differential flux normalization at 1 TeV of F{sub 0} = (9.6 {+-} 1.5{sub stat}(+ 5.7, -2.9){sub sys}) Multiplication-Sign 10{sup -14} TeV{sup -1} cm{sup -2} s{sup -1}. A power-law fit to the differential HE {gamma}-ray spectrum reveals a photon index of {Gamma} 2.24 {+-} 0.14{sub stat} {+-} 0.03{sub sys} and an integral flux between 200 MeV and 200 GeV of F(0.2-200 GeV) = (4.9 {+-} 1.0{sub stat} {+-} 0.3{sub sys}) Multiplication-Sign 10{sup -9} cm{sup -2} s{sup -1}. No evidence for a spectral break or turnover is found over the dynamic range of both the LAT instrument and the H.E.S.S. experiment: a combined fit of a power law to the HE and VHE {gamma}-ray data results in a differential photon index {Gamma} = 2.34 {+-} 0.03 with a p-value of 30%. The {gamma}-ray observations indicate that at least about 20% of the energy of the cosmic rays (CRs) capable of producing hadronic interactions is channeled into pion production. The smooth alignment between the spectra in the HE and VHE {gamma}-ray domain suggests that the same transport processes dominate in the entire energy range. Advection is most likely responsible for charged particle removal from the starburst nucleus from GeV to multiple TeV energies. In a hadronic scenario for the {gamma}-ray production, the single overall power-law spectrum observed would therefore correspond to the mean energy spectrum produced by the ensemble of CR sources in the starburst region.

  3. Spectrum-based network visualization for topology analysis.

    PubMed

    Hu, Xianlin; Lu, Aidong; Wu, Xintao

    2013-01-01

    Network visualization techniques have been widely used to explore social networks, which are crucial to many application domains. A proposed visual-analytics approach provides functions that were previously hard to obtain. Based on recent achievements in spectrum-based analysis, it uses the features of node distribution and coordinates in the high-dimensional spectral space. Specifically, three-stage node projection and dispersion on a k-dimensional sphere in the spectral space determines the network layout. To assist interactive exploration of network topologies, network visualization and interactive analysis let users filter nodes and edges in a way that's meaningful to the global topology structure.

  4. Multivariate statistical analysis of low-voltage EDS spectrum images

    SciTech Connect

    Anderson, I.M.

    1998-03-01

    Whereas energy-dispersive X-ray spectrometry (EDS) has been used for compositional analysis in the scanning electron microscope for 30 years, the benefits of using low operating voltages for such analyses have been explored only during the last few years. This paper couples low-voltage EDS with two other emerging areas of characterization: spectrum imaging and multivariate statistical analysis. The specimen analyzed for this study was a finished Intel Pentium processor, with the polyimide protective coating stripped off to expose the final active layers.

  5. A tool to include gamma analysis software into a quality assurance program.

    PubMed

    Agnew, Christina E; McGarry, Conor K

    2016-03-01

    To provide a tool to enable gamma analysis software algorithms to be included in a quality assurance (QA) program. Four image sets were created comprising two geometric images to independently test the distance to agreement (DTA) and dose difference (DD) elements of the gamma algorithm, a clinical step and shoot IMRT field and a clinical VMAT arc. The images were analysed using global and local gamma analysis with 2 in-house and 8 commercially available software encompassing 15 software versions. The effect of image resolution on gamma pass rates was also investigated. All but one software accurately calculated the gamma passing rate for the geometric images. Variation in global gamma passing rates of 1% at 3%/3mm and over 2% at 1%/1mm was measured between software and software versions with analysis of appropriately sampled images. This study provides a suite of test images and the gamma pass rates achieved for a selection of commercially available software. This image suite will enable validation of gamma analysis software within a QA program and provide a frame of reference by which to compare results reported in the literature from various manufacturers and software versions. Copyright © 2015. Published by Elsevier Ireland Ltd.

  6. Underground fluid composition analysis based on the near infrared spectrum

    NASA Astrophysics Data System (ADS)

    Li, Wenxi; Liao, Yanbiao; Zhang, Min

    2011-11-01

    The near-infrared spectrum is very practical for real-time analyzing in the field of industry. This paper describes the structure of optical system, which is a part of the well logging instruments. The optical system is designed to analyze the composition of underground fluid, using the differences between oil and water in near-infrared absorption. Using Beer- Lambert law, the article analyzes the light intensity when broad-spectrum light passes through the liquid. According to the results of analysis, a group of wavelength including center wavelength and bandwidth can be selected. With each selected wavelength, light intensity changes significantly as the concentration of liquid changes. By measuring the light intensity, the system can analyse the composition of underground fluid.

  7. Eigenvalue spectrum of the spheroidal harmonics: A uniform asymptotic analysis

    NASA Astrophysics Data System (ADS)

    Hod, Shahar

    2015-06-01

    The spheroidal harmonics Slm (θ ; c) have attracted the attention of both physicists and mathematicians over the years. These special functions play a central role in the mathematical description of diverse physical phenomena, including black-hole perturbation theory and wave scattering by nonspherical objects. The asymptotic eigenvalues {Alm (c) } of these functions have been determined by many authors. However, it should be emphasized that all the previous asymptotic analyzes were restricted either to the regime m → ∞ with a fixed value of c, or to the complementary regime | c | → ∞ with a fixed value of m. A fuller understanding of the asymptotic behavior of the eigenvalue spectrum requires an analysis which is asymptotically uniform in both m and c. In this paper we analyze the asymptotic eigenvalue spectrum of these important functions in the double limit m → ∞ and | c | → ∞ with a fixed m / c ratio.

  8. DMD mutation spectrum analysis in 613 Chinese patients with dystrophinopathy.

    PubMed

    Guo, Ruolan; Zhu, Guosheng; Zhu, Huimin; Ma, Ruiyu; Peng, Ying; Liang, Desheng; Wu, Lingqian

    2015-08-01

    Dystrophinopathy is a group of inherited diseases caused by mutations in the DMD gene. Within the dystrophinopathy spectrum, Duchenne and Becker muscular dystrophies are common X-linked recessive disorders that mainly feature striated muscle necrosis. We combined multiplex ligation-dependent probe amplification with Sanger sequencing to detect large deletions/duplications and point mutations in the DMD gene in 613 Chinese patients. A total of 571 (93.1%) patients were diagnosed, including 428 (69.8%) with large deletions/duplications and 143 (23.3%) with point mutations. Deletion/duplication breakpoints gathered mostly in introns 44-55. Reading frame rules could explain 88.6% of deletion mutations. We identified seventy novel point mutations that had not been previously reported. Spectrum expansion and genotype-phenotype analysis of DMD mutations on such a large sample size in Han Chinese population would provide new insights into the pathogenic mechanism underlying dystrophinopathies.

  9. Spectrum analysis of speech recognition via discrete Tchebichef transform

    NASA Astrophysics Data System (ADS)

    Ernawan, Ferda; Abu, Nur Azman; Suryana, Nanna

    2011-10-01

    Speech recognition is still a growing field. It carries strong potential in the near future as computing power grows. Spectrum analysis is an elementary operation in speech recognition. Fast Fourier Transform (FFT) is the traditional technique to analyze frequency spectrum of the signal in speech recognition. Speech recognition operation requires heavy computation due to large samples per window. In addition, FFT consists of complex field computing. This paper proposes an approach based on discrete orthonormal Tchebichef polynomials to analyze a vowel and a consonant in spectral frequency for speech recognition. The Discrete Tchebichef Transform (DTT) is used instead of popular FFT. The preliminary experimental results show that DTT has the potential to be a simpler and faster transformation for speech recognition.

  10. Spatiotemporal analysis of the appearance of gamma-band Microstates in resting state MEG.

    PubMed

    Kelsey, Matthew; Prior, Fred W; Larson-Prior, Linda J

    2015-01-01

    Spatiotemporal analysis of EEG signal has revealed a rich set of methods to quantify neuronal activity using spatially global topographic templates, called Microstates. These methods complement more traditional spectral analysis, which uses band limited source data to determine defining differences in band power and peak characteristics. The high sampling rate and increased resistance to high frequency noise of MEG data offers an opportunity to explore the utility of spatiotemporal analysis over a wider spectrum than in EEG. In this work, we explore the utility of representing band limited MEG source data using established microstate techniques, especially in gamma frequency bands - a range yet unexplored using these techniques. We develop methods for gauging the goodness-of-fit achieved by resultant microstate templates and demonstrate sensor-level dispersion characteristics across wide-band signals as well as across signals filtered by canonical bands. These analyses reveal that, while high-frequency-band derived microstate templates are visually lawful, they fail to exhibit important explained variance and dispersion characteristics present in low- and full-band data necessary to meet the requirements of a microstate model.

  11. Gamma radiation shielding analysis of lead-flyash concretes.

    PubMed

    Singh, Kanwaldeep; Singh, Sukhpal; Dhaliwal, A S; Singh, Gurmel

    2014-11-04

    Six samples of lead-flyash concrete were prepared with lead as an admixture and by varying flyash content - 0%, 20%, 30%, 40%, 50% and 60% (by weight) by replacing cement and keeping constant w/c ratio. Different gamma radiation interaction parameters used for radiation shielding design were computed theoretically and measured experimentally at 662keV, 1173keV and 1332keV gamma radiation energy using narrow transmission geometry. The obtained results were compared with ordinary-flyash concretes. The radiation exposure rate of gamma radiation sources used was determined with and without lead-flyash concretes.

  12. Multiplex polymerase chain reaction-based deletion analysis of spontaneous, gamma ray- and alpha-induced hprt mutants of CHO-K1 cells.

    PubMed

    Schwartz, J L; Rotmensch, J; Sun, J; An, J; Xu, Z; Yu, Y; Hsie, A W

    1994-11-01

    Independent Chinese hamster ovary (CHO)-K1 cell mutants at the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus were isolated from untreated, 60Co gamma ray- and 212Bi alpha-exposed cells and the genetic changes underlying the mutation determined by multiplex polymerase chain reaction (PCR)-based exon deletion analysis. In the 71 spontaneous mutants analyzed, 77.5% of the clones showed no change in exon number or size, 15.5% showed a loss of a single exon, 4.2% showed a loss of 2-8 exons, and 2.8% showed loss of all nine hprt exons (total gene deletion). Exposure to 6 Gy of gamma rays, which reduced survival levels to 10%, produced a significantly different deletion spectrum that was shifted toward deletions with 45% of the 20 mutants analyzed showing a loss of a single exon and 30% showing a loss of all nine exons. Exposure to 2 Gy alpha radiation from 212Bi, a 220Rn daughter, a dose which also reduced survival levels to about 10%, resulted in a deletion spectrum similar to the gamma-ray spectrum in that more than 75% of the 49 mutants analyzed were deletions. The alpha spectrum, however, was significantly different from both the spontaneous and gamma spectra with 55.1% of the alpha mutants showing a loss of all nine exons, 10.2% showing loss of a single exon, and 14.3% showing loss of 2-8 exons. Thus, alpha-radiation appears to produce larger intragenic deletions than gamma radiation. The results suggest that intragenic deletion size should be considered when low- and high linear energy transfer (LET) mutation spectra are compared.

  13. Polymerase chain reaction-deletion analysis of spontaneous, gamma ray-, and alpha-induced hprt mutants of CHO-K1 cells.

    SciTech Connect

    Schwartz, J. L.; Rotmensch, J.; Sun, J.; An, J.; Xu, Z.; Yu, Y.; Hsie, A. W.; Center for Mechanistic Biology and Biotechnology; Univ. of Chicago; Univ. of Texas Medical Branch

    1994-01-01

    Independent Chinese hamster ovary (CHO)-K1 cell mutants at the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus were isolated from untreated, {sup 60}Co {gamma} ray-and {sup 212}Bi {alpha}-exposed cells and the genetic changes underlying the mutation determined by multiplex polymerase chain reaction (PCR)-based exon deletion analysis. In the 71 spontaneous mutants analyzed, 77.5% of the clones showed no change in exon number or size, 15.5% showed a loss of a single exon, 4.2% showed a loss of 2-8 exons, and 2.8% showed loss of all nine hprt exons (total gene deletion). Exposure to 6 Gy of {gamma} rays, which reduced survival levels to 10%, produced a significantly different deletion spectrum that was shifted toward deletions with 45% of the 20 mutants analyzed showing a loss of a single exon and 30% showing a loss of all nine exons. Exposure to 2 Gy {alpha} radiation from 212Bi, a 220Rn daughter, a dose which also reduced survival levels to about 10%, resulted in a deletion spectrum similar to the {gamma}-ray spectrum in that more than 75% of the 49 mutants analyzed were deletions. The {alpha} spectrum, however, was significantly different from both the spontaneous and {gamma} spectra with 55.1% of the {alpha} mutants showing a loss of all nine exons, 10.2% showing loss of a single exon, and 14.3% showing loss of 2-8 exons. Thus, {alpha}-radiation appears to produce larger intragenic deletions than {gamma} radiation. The results suggest that intragenic deletion size should be considered when low- and high linear energy transfer (LET) mutation spectra are compared.

  14. Mixed Spectrum Analysis on fMRI Time-Series.

    PubMed

    Kumar, Arun; Lin, Feng; Rajapakse, Jagath C

    2016-06-01

    Temporal autocorrelation present in functional magnetic resonance image (fMRI) data poses challenges to its analysis. The existing approaches handling autocorrelation in fMRI time-series often presume a specific model of autocorrelation such as an auto-regressive model. The main limitation here is that the correlation structure of voxels is generally unknown and varies in different brain regions because of different levels of neurogenic noises and pulsatile effects. Enforcing a universal model on all brain regions leads to bias and loss of efficiency in the analysis. In this paper, we propose the mixed spectrum analysis of the voxel time-series to separate the discrete component corresponding to input stimuli and the continuous component carrying temporal autocorrelation. A mixed spectral analysis technique based on M-spectral estimator is proposed, which effectively removes autocorrelation effects from voxel time-series and identify significant peaks of the spectrum. As the proposed method does not assume any prior model for the autocorrelation effect in voxel time-series, varying correlation structure among the brain regions does not affect its performance. We have modified the standard M-spectral method for an application on a spatial set of time-series by incorporating the contextual information related to the continuous spectrum of neighborhood voxels, thus reducing considerably the computation cost. Likelihood of the activation is predicted by comparing the amplitude of discrete component at stimulus frequency of voxels across the brain by using normal distribution and modeling spatial correlations among the likelihood with a conditional random field. We also demonstrate the application of the proposed method in detecting other desired frequencies.

  15. The Soft Gamma-Ray Spectrum of A0535+26: Detection of an Absorption Feature at 110 keV by OSSE

    DTIC Science & Technology

    1995-01-01

    keV corresponds to a magnetic eld strength at the surface of the neutron star of 1 1013 G ( 5 1012 G if the rst harmonic is at 55 keV). Subject...headings: gamma rays: observation | line identi cation | stars : individual (A0535+26) | stars : magnetic elds | stars : neutron | X-rays: stars { 3... neutron - star paradigm for the hard-spectrum -ray bursts do show signi cant lling-in of the rst harmonic by two- decay of the second excited state

  16. Linearized spectrum correlation analysis for line emission measurements

    NASA Astrophysics Data System (ADS)

    Nishizawa, T.; Nornberg, M. D.; Den Hartog, D. J.; Sarff, J. S.

    2017-08-01

    A new spectral analysis method, Linearized Spectrum Correlation Analysis (LSCA), for charge exchange and passive ion Doppler spectroscopy is introduced to provide a means of measuring fast spectral line shape changes associated with ion-scale micro-instabilities. This analysis method is designed to resolve the fluctuations in the emission line shape from a stationary ion-scale wave. The method linearizes the fluctuations around a time-averaged line shape (e.g., Gaussian) and subdivides the spectral output channels into two sets to reduce contributions from uncorrelated fluctuations without averaging over the fast time dynamics. In principle, small fluctuations in the parameters used for a line shape model can be measured by evaluating the cross spectrum between different channel groupings to isolate a particular fluctuating quantity. High-frequency ion velocity measurements (100-200 kHz) were made by using this method. We also conducted simulations to compare LSCA with a moment analysis technique under a low photon count condition. Both experimental and synthetic measurements demonstrate the effectiveness of LSCA.

  17. The Spectrum of LSST Data Analysis Challenges: Kiloscale to Petascale

    NASA Astrophysics Data System (ADS)

    Loredo, Thomas J.; Babu, G. J.; Borne, K. D.; Feigelson, E. D.; Gray, A. G.; Informatics, LSST; Statistics Science Collaboration proposed

    2010-01-01

    The unprecedented science opportunities enabled by LSST's wide-fast-deep mode of operation are accompanied by equally unprecedented data analysis challenges, due to the huge size and synoptic scope of LSST data products. While the most obvious challenges are those due to the petabyte scale of fundamental LSST databases, new and difficult data analysis problems that span a broad range of sizes, types, and complexity, and require a matching breadth of methodological research, must also be addressed. Some smaller-scale LSST data products, such as multicolor light curves for individual objects, will present challenging statistics problems; e.g., requiring multivariate time series methods capable of handling nonuniform, non-simultaneous sampling with measurement errors. Very large-scale LSST data products, such as comprehensive catalogs of stars or galaxies, will require significant informatics/data mining innovation; e.g., to enable accurate classification or photo-z estimation for huge samples. These scales mark the boundaries of a broad spectrum of LSST data analysis problems; research-level informatics and statistics challenges arise in various combinations across this whole spectrum. We survey the diversity of forthcoming LSST data analysis problems and opportunities, highlighting representative problems that address compelling astronomical science and present significant methodological challenges involving both astrostatistics and astroinformatics.

  18. Spectrum properties analysis of different soil moisture content

    NASA Astrophysics Data System (ADS)

    Fang, Shenghui; Hu, Bo; Lin, Fan

    2009-10-01

    Soil moisture content is one of the most important factors in soil business. The basic of detecting soil moisture content using remote sensing technology is to analyze the relationship between soil moisture content and emissivity. In this paper, based on the analysis of spectrum collection and processing by a portable spectrometer, a set of measure schemes were first established which can accurately measure the reflectivity and emissivity of soil spectrum with different moisture content in near-infrared and thermal infrared bands. Then we selected different bare soil areas as the areas for survey, and studied the relationship of different moisture content and the spectrum curve in the soil both of the same kind and of different kind (like the soil whose structure has been modified caused by the change of organic matter contents or soil particle size). Finally, we emphasized on the quantitative relationship between soil reflectivity & emissivity and soil moisture content using the test data, and establish a model depicting the quantitative relationship above in near-infrared and thermal infrared bands.

  19. SER Analysis of MPPM-Coded MIMO-FSO System over Uncorrelated and Correlated Gamma-Gamma Atmospheric Turbulence Channels

    NASA Astrophysics Data System (ADS)

    Khallaf, Haitham S.; Garrido-Balsells, José M.; Shalaby, Hossam M. H.; Sampei, Seiichi

    2015-12-01

    The performance of multiple-input multiple-output free space optical (MIMO-FSO) communication systems, that adopt multipulse pulse position modulation (MPPM) techniques, is analyzed. Both exact and approximate symbol-error rates (SERs) are derived for both cases of uncorrelated and correlated channels. The effects of background noise, receiver shot-noise, and atmospheric turbulence are taken into consideration in our analysis. The random fluctuations of the received optical irradiance, produced by the atmospheric turbulence, is modeled by the widely used gamma-gamma statistical distribution. Uncorrelated MIMO channels are modeled by the α-μ distribution. A closed-form expression for the probability density function of the optical received irradiance is derived for the case of correlated MIMO channels. Using our analytical expressions, the degradation of the system performance with the increment of the correlation coefficients between MIMO channels is corroborated.

  20. Produced water characterization by prompt gamma-ray neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Meric, Ilker; Johansen, Geir A.; Holstad, Marie B.; Wang, Jiaxin; Gardner, Robin P.

    2011-12-01

    Multiphase gas/oil/water measurement has been and still is a challenging task within the petroleum industry. The requirements of measurement efficiency and accuracy have been continuously increasing at the same time as the trend is to use subsea installations. As a response, the design of the SOFA (Subsea Online Fluid Analyser) concept was initiated by Christian Michelsen Research in cooperation with the University of Bergen. The final design of the analyser is yet to be completed. The ultimate goal of this design is the development of a permanently installed subsea metering station which is capable of characterizing all of the components that can be found in multiphase flow. One of the key challenges in this design is the detailed characterization of produced water samples which includes the identification of salt ions in the sample and their weight percentages. In this work, use of prompt gamma-ray neutron activation analysis (PGNAA) in conjunction with the so-called Monte Carlo library least-squares (MCLLS) approach is considered for characterization of the produced water component. A relatively simple produced water sample was prepared and the prompt gamma-ray spectrum of the sample was recorded using a large 6" × 6" NaI(Tl) scintillation detector. A specific purpose Monte Carlo code named CEARCPG was used to generate the pertinent elemental libraries that are required in the MCLLS approach. The results of this feasibility study have shown that the PGNAA in conjunction with the MCLLS approach would be feasible for determining the amounts of salt ions that can be found in produced water samples.

  1. Application of Multidimensional Spectrum Analysis for Analytical Chemistry

    SciTech Connect

    Hatsukawa, Yuichi; Hayakawa, Takehito; Toh, Yosuke; Shinohara, Nobuo; Oshima, Masumi

    1999-12-31

    Feasibility of application of the multidimensional {gamma} ray spectroscopy for analytical chemistry was examined. Two reference igneous rock (JP-1, JB-1a) samples issued by the Geological Survey of Japan (GSJ) were irradiated at a research reactor with thermal neutrons, and {gamma} rays from the radioisotopes produced by neutron capture reactions were measured using a {gamma}-ray detector array. Simultaneously 27 elements were observed with no chemical separation.

  2. Application of multidimensional spectrum analysis for analytical chemistry

    SciTech Connect

    Hatsukawa, Yuichi; Hayakawa, Takehito; Toh, Yosuke; Shinohara, Nobuo; Oshima, Masumi

    1999-11-16

    Feasibility of application of the multidimensional {gamma} ray spectroscopy for analytical chemistry was examined. Two reference igneous rock (JP-1, JB-1a) samples issued by the Geological Survey of Japan (GSJ) were irradiated at a research reactor with thermal neutrons, and {gamma} rays from the radioisotopes produced by neutron capture reactions were measured using a {gamma}-ray detector array. Simultaneously 27 elements were observed with no chemical separation.

  3. In situ characterization of hazardous contaminants using prompt gamma neutron activation analysis

    SciTech Connect

    Ruddy, F.H.; Congedo, T.V.; Seidel, J.G.; Gonzalez, J.L.; Weigle, D.H.

    1993-12-31

    Prompt Gamma Neutron Activation Analysis (PGNAA) has been developed for real-time, in situ measurements of contaminant elements in soil. Pulsed neutron activation coupled with state-of-the-art high count rate throughput electronics and time-sequenced gamma ray energy analysis have been used to obtain sensitivities at the trace level for uranium in soil. The results of detailed neutron dosimetry and prompt neutron-induced gamma ray transport measurements carried out using a soil test matrix will be reported. Initial field deployment of the PGNAA system at a former solution uranium mine in Bruni, Texas will also be described.

  4. Lunar elemental analysis obtained from the Apollo gamma-ray and X-ray remote sensing experiment

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    Gamma-ray and X-ray spectrometers carried in the service modules of the Apollo 15 and Apollo 16 spacecraft were employed for compositional mapping of the lunar surface. The measurements involved the observation of the intensity and characteristic energy distribution of gamma rays and X-rays emitted from the lunar surface. A large-scale compositional map of over 10 percent of the lunar surface was obtained from an analysis of the observed spectra. The objective of the X-ray experiment was to measure the K spectral lines from Mg, Al, and Si. Spectra were obtained and the data were reduced to Al/Si and Mg/Si intensity ratios and ultimately to chemical ratios. Analyses of the results have indicated (1) that the Al/Si ratios are highest in the lunar highlands and considerably lower in the maria, and (2) that the Mg/Si concentrations generally show the opposite relationship. The objective of the gamma-ray experiment was to measure the natural and cosmic-ray-induced activity emission spectrum. At this time, the elemental abundances for Th, U, K, Fe, Ti, Si, and O have been determined over a number of major lunar regions. Regions of relatively high natural radioactivity were found in the Mare Imbrium and Oceanus Procellarum regions.

  5. Measurement and Analysis of Gamma-Rays Emitted From Spent Nuclear Fuel Above 3 MeV

    SciTech Connect

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

    2013-12-01

    The gamma-ray spectrum of spent nuclear fuel in the 3- to 6-MeV energy range is important for active interrogation since emitted 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 ll 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.

  6. Improving the gamma analysis comparison using an unbinned multivariate test

    NASA Astrophysics Data System (ADS)

    Ramos Garcia, Luis Isaac; Pérez Azorín, José Fernando; Aguilar-Redondo, Pedro-Borja; Moran-Velasco, Verónica

    2017-09-01

    In this study, we present a new procedure for the comparison of two dose matrices by means of a statistical test. A statistical distance is proposed to decide whether the difference between the two matrices is statistically significant. This statistical test is based on the square difference between the experimental and expected gamma matrix results. The expected gamma matrix is calculated by simulating the measurement process. For comparison purposes, the significance level of the test was chosen to give the same statistical significance as 90% of gamma-pass rate. The performance of the statistical distance is checked against 53 VMAT. The power of the presented test was compared using simulations with the 90% gamma-pass rate criteria for two cases in which intentional errors are introduced. In both cases, the test is uniformly more powerful. According to the test, two of the measured plans have a significant difference with calculated matrices, although the gamma pass rate measured was always greater than 90%.

  7. Improving the gamma analysis comparison using an unbinned multivariate test.

    PubMed

    Ramos Garcia, Luis Isaac; Pérez Azorín, José Fernando; Aguilar-Redondo, Pedro-Borja; Moran-Velasco, Verónica

    2017-09-01

    In this study, we present a new procedure for the comparison of two dose matrices by means of a statistical test. A statistical distance is proposed to decide whether the difference between the two matrices is statistically significant. This statistical test is based on the square difference between the experimental and expected gamma matrix results. The expected gamma matrix is calculated by simulating the measurement process. For comparison purposes, the significance level of the test was chosen to give the same statistical significance as 90% of gamma-pass rate. The performance of the statistical distance is checked against 53 VMAT. The power of the presented test was compared using simulations with the 90% gamma-pass rate criteria for two cases in which intentional errors are introduced. In both cases, the test is uniformly more powerful. According to the test, two of the measured plans have a significant difference with calculated matrices, although the gamma pass rate measured was always greater than 90%.

  8. Graphical model based multivariate analysis (GAMMA): an open-source, cross-platform neuroimaging data analysis software package.

    PubMed

    Chen, Rong; Herskovits, Edward H

    2012-04-01

    The GAMMA suite is an open-source, cross-platform data-mining software package designed to analyze neuroimaging data. Analyzing brain image volumes is a very challenging problem, due to undersampling and the potential for multivariate nonlinear interactions among variables. The GAMMA suite provides a set of tools to facilitate the analysis of neuroimaging data.

  9. Lead foil wrapping of the plastic scintillators for the gamma ray detection: optical reflector or spectrum intensifier?

    NASA Astrophysics Data System (ADS)

    Taheri, A.; Askari, M.; Taghan Sasanpour, M.

    2017-08-01

    This paper studies the effect of lead wrapping on the response of the plastic scintillators as gamma detectors. Experimental tests and Geant4 simulations showed that lead wrapping cannot increase the gamma absorption efficiency of the detector but, as a reflector, it can improve the optical properties of the detector. The reflectivity of the lead foil as an optical reflector was determined equal to 66% using an experimental-simulation combined method. Based on the obtained results, the optical collection efficiency of the detector was also increased about 4% after employing the lead reflector.

  10. The soft gamma-ray spectrum of A0535+26: Detection of an absorption feature at 110 keV by OSSE

    NASA Technical Reports Server (NTRS)

    Grove, J. E.; Strickman, M. S.; Johnson, W. N.; Kurfess, J. D.; Kinzer, R. L.; Starr, C. H.; Jung, G. V.; Kendziorra, E.; Maisack, M.; Staubert, R.

    1995-01-01

    We present soft gamma-ray observations by the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory (GRO) of the transient X-ray binary pulsar A0535+26. The observations were made 1994 February 8-17, immediately prior to the peak of a giant outburst. The phase averaged spectrum is complex and cannot be described by a single-component model. We find that structure in the spectrum above 100 keV can best be modeled by an absorption feature near 110 keV, which we interepret as the signature of cyclotron resonant scattering. Because of OSSE's 45 keV threshold, we are unable to make a definitive statement on the presence of a 55 keV absorption line; however, we can conclude that if this line does exist, it must have a smaller optical depth than the line at 110 keV. A first harmonic (=fundamental) cyclotron resonance at 110 keV corresponds to a magnetic field strength at the surface of the neutron star of approximately 1 x 10(exp 13) G (approximately 5 x 10(exp 12) G if the first harmonic is at 55 keV).

  11. Disentangling Hadronic and Leptonic Cascade Scenarios from the Very-High-Energy Gamma-Ray Emission of Distant Hard-Spectrum Blazars

    DOE PAGES

    Takami, Hajime; Murase, Kohta; Dermer, Charles D.

    2013-06-26

    We show that recent data from the Fermi Large Area Telescope have revealed about a dozen distant hard-spectrum blazars that have very-high-energy (VHE; ≳ 100 eV) photons associated with them, but most of them have not yet been detected by imaging atmospheric Cherenkov Telescopes. Most of these high-energy gamma-ray spectra, like those of other extreme high-frequency peaked BL Lac objects, can be well explained either by gamma rays emitted at the source or by cascades induced by ultra-high-energy cosmic rays, as we show specifically for KUV 00311–1938. We consider the prospects for detection of the VHE sources by the plannedmore » Cherenkov Telescope Array (CTA) and show how it can distinguish the two scenarios by measuring the integrated flux above ~500 GeV (depending on source redshift) for several luminous sources with z ≲ 1 in the sample. Strong evidence for the origin of ultra-high-energy cosmic rays could be obtained from VHE observations with CTA. Depending on redshift, if the often quoted redshift of KUV 00311–1938 (z = 0.61) is believed, then preliminary H.E.S.S. data favor cascades induced by ultra-high-energy cosmic rays. Lastly, accurate redshift measurements of hard-spectrum blazars are essential for this study.« less

  12. DISENTANGLING HADRONIC AND LEPTONIC CASCADE SCENARIOS FROM THE VERY-HIGH-ENERGY GAMMA-RAY EMISSION OF DISTANT HARD-SPECTRUM BLAZARS

    SciTech Connect

    Takami, Hajime; Murase, Kohta; Dermer, Charles D. E-mail: murase@ias.edu

    2013-07-10

    Recent data from the Fermi Large Area Telescope have revealed about a dozen distant hard-spectrum blazars that have very-high-energy (VHE; {approx}> 100 GeV) photons associated with them, but most of them have not yet been detected by imaging atmospheric Cherenkov Telescopes. Most of these high-energy gamma-ray spectra, like those of other extreme high-frequency peaked BL Lac objects, can be well explained either by gamma rays emitted at the source or by cascades induced by ultra-high-energy cosmic rays, as we show specifically for KUV 00311-1938. We consider the prospects for detection of the VHE sources by the planned Cherenkov Telescope Array (CTA) and show how it can distinguish the two scenarios by measuring the integrated flux above {approx}500 GeV (depending on source redshift) for several luminous sources with z {approx}< 1 in the sample. Strong evidence for the origin of ultra-high-energy cosmic rays could be obtained from VHE observations with CTA. Depending on redshift, if the often quoted redshift of KUV 00311-1938 (z = 0.61) is believed, then preliminary H.E.S.S. data favor cascades induced by ultra-high-energy cosmic rays. Accurate redshift measurements of hard-spectrum blazars are essential for this study.

  13. Disentangling Hadronic and Leptonic Cascade Scenarios from the Very-High-Energy Gamma-Ray Emission of Distant Hard-Spectrum Blazars

    SciTech Connect

    Takami, Hajime; Murase, Kohta; Dermer, Charles D.

    2013-06-26

    We show that recent data from the Fermi Large Area Telescope have revealed about a dozen distant hard-spectrum blazars that have very-high-energy (VHE; ≳ 100 eV) photons associated with them, but most of them have not yet been detected by imaging atmospheric Cherenkov Telescopes. Most of these high-energy gamma-ray spectra, like those of other extreme high-frequency peaked BL Lac objects, can be well explained either by gamma rays emitted at the source or by cascades induced by ultra-high-energy cosmic rays, as we show specifically for KUV 00311–1938. We consider the prospects for detection of the VHE sources by the planned Cherenkov Telescope Array (CTA) and show how it can distinguish the two scenarios by measuring the integrated flux above ~500 GeV (depending on source redshift) for several luminous sources with z ≲ 1 in the sample. Strong evidence for the origin of ultra-high-energy cosmic rays could be obtained from VHE observations with CTA. Depending on redshift, if the often quoted redshift of KUV 00311–1938 (z = 0.61) is believed, then preliminary H.E.S.S. data favor cascades induced by ultra-high-energy cosmic rays. Lastly, accurate redshift measurements of hard-spectrum blazars are essential for this study.

  14. Impaired gamma-band activity during perceptual organization in adults with autism spectrum disorders: evidence for dysfunctional network activity in frontal-posterior cortices.

    PubMed

    Sun, Limin; Grützner, Christine; Bölte, Sven; Wibral, Michael; Tozman, Tahmine; Schlitt, Sabine; Poustka, Fritz; Singer, Wolf; Freitag, Christine M; Uhlhaas, Peter J

    2012-07-11

    Current theories of the pathophysiology of autism spectrum disorders (ASD) have focused on abnormal temporal coordination of neural activity in cortical circuits as a core impairment of the disorder. In the current study, we examined the possibility that gamma-band activity may be crucially involved in aberrant brain functioning in ASD. Magneto-encephalographic (MEG) data were recorded from 13 adult human participants with ASD and 16 controls during the presentation of Mooney faces. MEG data were analyzed in the 25-150 Hz frequency range and a beamforming approach was used to identify the sources of spectral power. Participants with ASD showed elevated reaction times and reduced detection rates during the perception of upright Mooney faces, while responses to inverted stimuli were in the normal range. Impaired perceptual organization in the ASD group was accompanied by a reduction in both the amplitude and phase locking of gamma-band activity. A beamforming approach identified distinct networks during perceptual organization in controls and participants with ASD. In controls, perceptual organization of Mooney faces involved increased 60-120 Hz activity in a frontoparietal network, while in the ASD group stronger activation was found in visual regions. These findings highlight the contribution of impaired gamma-band activity toward complex visual processing in ASD, suggesting atypical modulation of high-frequency power in frontoposterior networks.

  15. Multicomponent analysis of total COS-B gamma-ray data at intermediate lattitudes

    NASA Technical Reports Server (NTRS)

    Strong, A. W.; Bloemen, J. B. G. M.; Hemsen, W.; Mayer-Hasselwander, H. A.

    1985-01-01

    The final COS-B database was used to study the gamma ray emission in the latitude range 10 deg /b/ 20 deg in terms of a four component model. The emissivity spectrum of the local interstellar medium is derived and compared with that found in previous studies. The intensity-Compton component is determined from the fitting procedure and is in good agreement with theoretical values.

  16. Analysis of gamma ray spectra measured by Mars Odyssey

    NASA Astrophysics Data System (ADS)

    Evans, Larry G.; Reedy, Robert C.; Starr, Richard D.; Kerry, Kristopher E.; Boynton, William V.

    2006-12-01

    Gamma ray spectra measured by the Mars Odyssey gamma ray spectrometer while in orbit around Mars were analyzed to identify the sources of 334 observed peaks and features. Most peaks were of a standard Gaussian shape with a low-energy tail. However, Doppler-broadened and sawtooth-shaped peaks were also observed in the spectra. The sources of most peaks were identified. Many peaks come from the gamma ray detector material or materials around the detector, particularly Ti and Mg. Identifications were often confirmed by analyzing other spectra, such as those measured during the cruise to Mars, before and after the boom deployment, at the end of solar particle events, and over thick frozen CO2 polar caps during winters.

  17. Gamma radiological surveys of the Oak Ridge Reservation, Paducah Gaseous Diffusion Plant, and Portsmouth Gaseous Diffusion Plant, 1990-1993, and overview of data processing and analysis by the Environmental Restoration Remote Sensing Program, Fiscal Year 1995

    SciTech Connect

    Smyre, J.L.; Moll, B.W.; King, A.L.

    1996-06-01

    Three gamma radiological surveys have been conducted under auspices of the ER Remote Sensing Program: (1) Oak Ridge Reservation (ORR) (1992), (2) Clinch River (1992), and (3) Portsmouth Gaseous Diffusion Plant (PORTS) (1993). In addition, the Remote Sensing Program has acquired the results of earlier surveys at Paducah Gaseous Diffusion Plant (PGDP) (1990) and PORTS (1990). These radiological surveys provide data for characterization and long-term monitoring of U.S. Department of Energy (DOE) contamination areas since many of the radioactive materials processed or handled on the ORR, PGDP, and PORTS are direct gamma radiation emitters or have gamma emitting daughter radionuclides. High resolution airborne gamma radiation surveys require a helicopter outfitted with one or two detector pods, a computer-based data acquisition system, and an accurate navigational positioning system for relating collected data to ground location. Sensors measure the ground-level gamma energy spectrum in the 38 to 3,026 KeV range. Analysis can provide gamma emission strength in counts per second for either gross or total man-made gamma emissions. Gross count gamma radiation includes natural background radiation from terrestrial sources (radionuclides present in small amounts in the earth`s soil and bedrock), from radon gas, and from cosmic rays from outer space as well as radiation from man-made radionuclides. Man-made count gamma data include only the portion of the gross count that can be directly attributed to gamma rays from man-made radionuclides. Interpretation of the gamma energy spectra can make possible the determination of which specific radioisotopes contribute to the observed man-made gamma radiation, either as direct or as indirect (i.e., daughter) gamma energy from specific radionuclides (e.g., cesium-137, cobalt-60, uranium-238).

  18. Digital discrimination of neutrons and gamma-rays in organic scintillation detectors using moment analysis.

    PubMed

    Xie, Xufei; Zhang, Xing; Yuan, Xi; Chen, Jinxiang; Li, Xiangqing; Zhang, Guohui; Fan, Tieshuan; Yuan, Guoliang; Yang, Jinwei; Yang, Qingwei

    2012-09-01

    Digital discrimination of neutron and gamma-ray events in an organic scintillator has been investigated by moment analysis. Signals induced by an americium-beryllium (Am/Be) isotropic neutron source in a stilbene crystal detector have been sampled with a flash analogue-to-digital converter (ADC) of 1 GSamples/s sampling rate and 10-bit vertical resolution. Neutrons and gamma-rays have been successfully discriminated with a threshold corresponding to gamma-ray energy about 217 keV. Moment analysis has also been verified against the results assessed by a time-of-flight (TOF) measurement. It is shown that the classification of neutrons and gamma-rays afforded by moment analysis is consistent with that achieved by digital TOF measurement. This method has been applied to analyze the data acquired from the stilbene crystal detector in mixed radiation field of the HL-2A tokamak deuterium plasma discharges and the results are described.

  19. Digital discrimination of neutrons and gamma-rays in organic scintillation detectors using moment analysis

    SciTech Connect

    Xie Xufei; Zhang Xing; Yuan Xi; Chen Jinxiang; Li Xiangqing; Zhang Guohui; Fan Tieshuan; Yuan Guoliang; Yang Jinwei; Yang Qingwei

    2012-09-15

    Digital discrimination of neutron and gamma-ray events in an organic scintillator has been investigated by moment analysis. Signals induced by an americium-beryllium (Am/Be) isotropic neutron source in a stilbene crystal detector have been sampled with a flash analogue-to-digital converter (ADC) of 1 GSamples/s sampling rate and 10-bit vertical resolution. Neutrons and gamma-rays have been successfully discriminated with a threshold corresponding to gamma-ray energy about 217 keV. Moment analysis has also been verified against the results assessed by a time-of-flight (TOF) measurement. It is shown that the classification of neutrons and gamma-rays afforded by moment analysis is consistent with that achieved by digital TOF measurement. This method has been applied to analyze the data acquired from the stilbene crystal detector in mixed radiation field of the HL-2A tokamak deuterium plasma discharges and the results are described.

  20. Digital discrimination of neutrons and gamma-rays in organic scintillation detectors using moment analysis

    NASA Astrophysics Data System (ADS)

    Xie, Xufei; Zhang, Xing; Yuan, Xi; Chen, Jinxiang; Li, Xiangqing; Zhang, Guohui; Fan, Tieshuan; Yuan, Guoliang; Yang, Jinwei; Yang, Qingwei

    2012-09-01

    Digital discrimination of neutron and gamma-ray events in an organic scintillator has been investigated by moment analysis. Signals induced by an americium-beryllium (Am/Be) isotropic neutron source in a stilbene crystal detector have been sampled with a flash analogue-to-digital converter (ADC) of 1 GSamples/s sampling rate and 10-bit vertical resolution. Neutrons and gamma-rays have been successfully discriminated with a threshold corresponding to gamma-ray energy about 217 keV. Moment analysis has also been verified against the results assessed by a time-of-flight (TOF) measurement. It is shown that the classification of neutrons and gamma-rays afforded by moment analysis is consistent with that achieved by digital TOF measurement. This method has been applied to analyze the data acquired from the stilbene crystal detector in mixed radiation field of the HL-2A tokamak deuterium plasma discharges and the results are described.

  1. Improved neutron-gamma discrimination for a 6Li-glass neutron detector using digital signal analysis methods

    DOE PAGES

    Wang, Cai -Lin; Riedel, Richard A.

    2016-01-14

    A 6Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at SNS. Traditional pulse-height analysis (PHA) for neutron-gamma discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 104. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, five digital signal analysis methods of individual waveforms from PMTs were proposed using: i). pulse-amplitude histogram; ii). power spectrum analysis combined with the maximum pulse amplitude; iii). two event parameters (a1, b0) obtained from Wiener filter; iv). an effective amplitude (m)more » obtained from an adaptive least-mean-square (LMS) filter; and v). a cross-correlation (CC) coefficient between an individual waveform and a reference. The NGD ratios can be 1-102 times those from traditional PHA method. A brighter scintillator GS2 has better NGD ratio than GS20, but lower neutron detection efficiency. The ultimate NGD ratio is related to the ambient, high-energy background events. Moreover, our results indicate the NGD capability of neutron Anger cameras can be improved using digital signal analysis methods and brighter neutron scintillators.« less

  2. Improved neutron-gamma discrimination for a 6Li-glass neutron detector using digital signal analysis methods

    SciTech Connect

    Wang, Cai -Lin; Riedel, Richard A.

    2016-01-14

    A 6Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at SNS. Traditional pulse-height analysis (PHA) for neutron-gamma discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 104. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, five digital signal analysis methods of individual waveforms from PMTs were proposed using: i). pulse-amplitude histogram; ii). power spectrum analysis combined with the maximum pulse amplitude; iii). two event parameters (a1, b0) obtained from Wiener filter; iv). an effective amplitude (m) obtained from an adaptive least-mean-square (LMS) filter; and v). a cross-correlation (CC) coefficient between an individual waveform and a reference. The NGD ratios can be 1-102 times those from traditional PHA method. A brighter scintillator GS2 has better NGD ratio than GS20, but lower neutron detection efficiency. The ultimate NGD ratio is related to the ambient, high-energy background events. Moreover, our results indicate the NGD capability of neutron Anger cameras can be improved using digital signal analysis methods and brighter neutron scintillators.

  3. Improved neutron-gamma discrimination for a {sup 6}Li-glass neutron detector using digital signal analysis methods

    SciTech Connect

    Wang, C. L. Riedel, R. A.

    2016-01-15

    A {sup 6}Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at Spallation Neutron Source. Traditional Pulse-Height Analysis (PHA) for Neutron-Gamma Discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 10{sup 4}. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, six digital signal analysis methods of individual waveforms acquired from photomultiplier tubes were proposed using (i) charge integration, (ii) pulse-amplitude histograms, (iii) power spectrum analysis combined with the maximum pulse-amplitude, (iv) two event parameters (a{sub 1}, b{sub 0}) obtained from a Wiener filter, (v) an effective amplitude (m) obtained from an adaptive least-mean-square filter, and (vi) a cross-correlation coefficient between individual and reference waveforms. The NGD ratios are about 70 times those from the traditional PHA method. Our results indicate the NGD capabilities of neutron Anger cameras based on GS20 scintillators can be significantly improved with digital signal analysis methods.

  4. Improved neutron-gamma discrimination for a 6Li-glass neutron detector using digital signal analysis methods

    NASA Astrophysics Data System (ADS)

    Wang, C. L.; Riedel, R. A.

    2016-01-01

    A 6Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at Spallation Neutron Source. Traditional Pulse-Height Analysis (PHA) for Neutron-Gamma Discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 104. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, six digital signal analysis methods of individual waveforms acquired from photomultiplier tubes were proposed using (i) charge integration, (ii) pulse-amplitude histograms, (iii) power spectrum analysis combined with the maximum pulse-amplitude, (iv) two event parameters (a1, b0) obtained from a Wiener filter, (v) an effective amplitude (m) obtained from an adaptive least-mean-square filter, and (vi) a cross-correlation coefficient between individual and reference waveforms. The NGD ratios are about 70 times those from the traditional PHA method. Our results indicate the NGD capabilities of neutron Anger cameras based on GS20 scintillators can be significantly improved with digital signal analysis methods.

  5. Prompt gamma neutron activation analysis for multi-element measurement with series samples

    NASA Astrophysics Data System (ADS)

    Yang, J. B.; Yang, Y. G.; Li, Y. J.; Tuo, X. G.; Li, Z.; Cheng, Y.; Mou, Y. F.; Huang, W. Q.

    2013-05-01

    The on-line prompt gamma neutron activation analysis (PGNAA) system is used to measure a series of prepared experimental samples to obtain the prompt characteristic γ-rays of the elements Ca, Fe, Si, Al, Mg and S in the examples of SiO2, Al2O3, MgO, CaO (powder), CaO (block), CaCO3, Fe2O3, Fe3O4 and S. The γ-ray energies are: Si, 3.54 or 4.93 MeV Ca, 4.42 or 6.42 MeV S, 5.42 MeV Fe, 5.92 or 7.63 MeV. Meanwhile, the prompt γ-rays of the main elements are measured in an experiment in which SiO2, Al2O3, MgO, CaO (powder), CaO (block), CaCO3, Fe2O3, Fe3O4 and S are blended to constitute a cement sample. The prompt γ-rays of S will contribute more with increase in S mass, as known from the experiment concerning the prompt γ-ray spectrum for different masses of S.

  6. Impact of gamma analysis parameters on dose evaluation using Gafchromic EBT2 films

    NASA Astrophysics Data System (ADS)

    Lee, Seu-Ran; Park, Ji-Yeon; Suh, Tae-Suk; Park, Hae-Jin; Lee, Jeong-Woo; Jung, Won-Gyun

    2012-10-01

    To recommend optimal gamma analysis parameters (grid size and search range) for detecting dose errors, we evaluated the impact of gamma models and parameters on dose verification in volumetric modulated fields. Delivered doses were verified under open, 45° wedged, and volumetric modulated fields for prostate, anal, head and neck, and brain cancer by using Gafchromic EBT2 films for gamma evaluation. Two gamma models (a conventional method and a modified method to compensate for unintended dose errors caused by misalignments between reference and evaluated matrixes) were employed. The variation in the detected dose errors was evaluated in each gamma model for different grid sizes (0.5, 1, and 2 mm) and search ranges (1, 2, and 4 mm) applied to determine distant-to-agreement. The dose discrepancy of each evaluation was qualitatively and quantitatively evaluated using a pass ratio in analysis software developed in-house. The modified gamma model with a small search range and grid size showed a higher pass ratio than the conventional model in volumetric modulated arc therapy. The pass ratio for 2 mm grid size decreased by over 40% as compared to that for 1 mm grid size. The pass ratio decreased by more than 30% as the search range was increased from 1 mm to 4 mm. Therefore, 1 mm grid size and 1 mm search range may be appropriate to evaluate dose errors in modulated fields after using the modified gamma model.

  7. Interferon-gamma of the giant panda (Ailuropoda melanoleuca): complementary DNA cloning, expression, and phylogenetic analysis.

    PubMed

    Tao, Yaqiong; Zeng, Bo; Xu, Liu; Yue, Bisong; Yang, Dong; Zou, Fangdong

    2010-01-01

    Interferon-gamma (IFN-gamma) is the only member of type II IFN and is vital in the regulation of immune and inflammatory responses. Herein we report the cloning, expression, and sequence analysis of IFN-gamma from the giant panda (Ailuropoda melanoleuca). The open reading frame of this gene is 501 base pair in length and encodes a polypeptide consisting of 166 amino acids. All conserved N-linked glycosylation sites and cysteine residues among carnivores were found in the predicted amino acid sequence of the giant panda. Recombinant giant panda IFN-gamma with a V5 epitope and polyhistidine tag was expressed in HEK293 host cells and confirmed by Western blotting. Phylogenetic analysis of mammalian IFN-gamma-coding sequences indicated that the giant panda IFN-gamma was closest to that of carnivores, then to ungulates and dolphin, and shared a distant relationship with mouse and human. These results represent a first step into the study of IFN-gamma in giant panda.

  8. Neutron-stimulated gamma ray analysis of soil

    USDA-ARS?s Scientific Manuscript database

    The chapter will discuss methods to use gamma rays to measure elements in soil. In regard to land management, there is a need to develop a non-destructive, non-contact, in-situ method of determining soil elements distributed in a soil volume or on soil surface. A unique method having all of above ...

  9. Code System for Isotope Identification by Gamma-Ray Analysis

    SciTech Connect

    1996-01-01

    For a set of a priori given nuclides taken from a work library, DIMEN uses median estimates of the peak areas and estimates of their errors to produce a list of possible nuclides matching a gamma-ray line and some measure of the reliability of this assignment.

  10. Bayesian Angular Power Spectrum Analysis of Interferometric Data

    NASA Astrophysics Data System (ADS)

    Sutter, P. M.; Wandelt, Benjamin D.; Malu, Siddarth S.

    2012-09-01

    We present a Bayesian angular power spectrum and signal map inference engine which can be adapted to interferometric observations of anisotropies in the cosmic microwave background (CMB), 21 cm emission line mapping of galactic brightness fluctuations, or 21 cm absorption line mapping of neutral hydrogen in the dark ages. The method uses Gibbs sampling to generate a sampled representation of the angular power spectrum posterior and the posterior of signal maps given a set of measured visibilities in the uv-plane. We use a mock interferometric CMB observation to demonstrate the validity of this method in the flat-sky approximation when adapted to take into account arbitrary coverage of the uv-plane, mode-mode correlations due to observations on a finite patch, and heteroschedastic visibility errors. The computational requirements scale as {O}(n_p log n_p) where np measures the ratio of the size of the detector array to the inter-detector spacing, meaning that Gibbs sampling is a promising technique for meeting the data analysis requirements of future cosmology missions.

  11. BAYESIAN ANGULAR POWER SPECTRUM ANALYSIS OF INTERFEROMETRIC DATA

    SciTech Connect

    Sutter, P. M.; Wandelt, Benjamin D.; Malu, Siddarth S.

    2012-09-15

    We present a Bayesian angular power spectrum and signal map inference engine which can be adapted to interferometric observations of anisotropies in the cosmic microwave background (CMB), 21 cm emission line mapping of galactic brightness fluctuations, or 21 cm absorption line mapping of neutral hydrogen in the dark ages. The method uses Gibbs sampling to generate a sampled representation of the angular power spectrum posterior and the posterior of signal maps given a set of measured visibilities in the uv-plane. We use a mock interferometric CMB observation to demonstrate the validity of this method in the flat-sky approximation when adapted to take into account arbitrary coverage of the uv-plane, mode-mode correlations due to observations on a finite patch, and heteroschedastic visibility errors. The computational requirements scale as O(n{sub p} log n{sub p}) where n{sub p} measures the ratio of the size of the detector array to the inter-detector spacing, meaning that Gibbs sampling is a promising technique for meeting the data analysis requirements of future cosmology missions.

  12. The pulse spectrum analysis at three stages of pregnancy.

    PubMed

    Liao, Yin-Tzu; Chen, Huey-Yi; Huang, Chin-Ming; Ho, Ming; Lin, Jaung-Geng; Chiu, Chun-Chien; Wang, Hong-Song; Chen, Fun-jou

    2012-04-01

    This study is the first to detect the radial pulses of the three diagnosis positions (inch, bar, and cubit) in both wrists (six positions) by pulse spectrum analysis. The purpose of this study was to identify the difference among pulses of the six positions at three stages of pregnancy and to examine whether the results of this study agree with the theory of Traditional Chinese Medicine (TCM), which states that the cubit pulse shows unique changes for an expectant woman and that the pulse changes coincide with the progression of gestation. One hundred and fifty (150) healthy pregnant women were divided into three groups according to gestational age (9-14 weeks, 20-28 weeks, and 32-37 weeks of gestation) and 50 healthy nonpregnant women were used as controls. A pulse analyzer was used to detect the six positions of the radial pulses and to calculate the 10 relative energy values of the spectrum's harmonics of the six positions. Results show that most of the 10 relative spectral energy values of the right and left cubits are statistically (p<0.01) higher than those of the inch for the pregnant women as compared with the nonpregnant women. In addition, the 10 relative spectral energy values of the six positions are not identical at the three stages of pregnancy. The cubit pulse is unique for pregnant women, which is consistent with the theory of TCM. In addition, the pulse conditions at the three stages of pregnancy are dissimilar.

  13. Investigations on neutron-induced prompt gamma ray analysis of bulk samples.

    PubMed

    Dokhale, P A; Csikai, J; Oláh, L

    2001-06-01

    A systematic investigation was carried out for the improvement of the prompt gamma interrogation method used for contraband detection by the pulsed fast/thermal neutron analysis (PFTNA) technique. Optimizations of source detector shielding and geometry, role of the type and dimension of the gamma detector, attenuation of neutrons and gamma rays in bulky samples were also studied. Results obtained for both the shielding materials and elemental content of cocaine simulants have been compared with the values calculated by the MCNP-4A code.

  14. Analysis of the gamma spectra of the uranium, actinium, and thorium decay series

    SciTech Connect

    Momeni, M.H.

    1981-09-01

    This report describes the identification of radionuclides in the uranium, actinium, and thorium series by analysis of gamma spectra in the energy range of 40 to 1400 keV. Energies and absolute efficiencies for each gamma line were measured by means of a high-resolution germanium detector and compared with those in the literature. A gamma spectroscopy method, which utilizes an on-line computer for deconvolution of spectra, search and identification of each line, and estimation of activity for each radionuclide, was used to analyze soil and uranium tailings, and ore.

  15. Analysis of the COS B data for evidence of linear polarization of Vela pulsar gamma rays

    NASA Technical Reports Server (NTRS)

    Mattox, John R.; Mayer-Hasselwander, Hans A.; Strong, Andy W.

    1990-01-01

    The COS B spark chamber telescope observations of the Vela pulsar were analyzed for gamma-ray polarization. No significant quadrupole moment is found in the azimuthal distribution of the electron-positron pair production planes. However, analysis of the sensitivity indicates that even 100-percent polarization would not be detected. Therefore, the null result does not constrain the polarization of the Vela pulsar gamma-ray emission. This result contradicts the report of Caraveo et al. (1988) of possible evidence for polarization of the Vela pulsar gamma rays.

  16. Analysis of the COS B data for evidence of linear polarization of Vela pulsar gamma rays

    NASA Technical Reports Server (NTRS)

    Mattox, John R.; Mayer-Hasselwander, Hans A.; Strong, Andy W.

    1990-01-01

    The COS B spark chamber telescope observations of the Vela pulsar were analyzed for gamma-ray polarization. No significant quadrupole moment is found in the azimuthal distribution of the electron-positron pair production planes. However, analysis of the sensitivity indicates that even 100-percent polarization would not be detected. Therefore, the null result does not constrain the polarization of the Vela pulsar gamma-ray emission. This result contradicts the report of Caraveo et al. (1988) of possible evidence for polarization of the Vela pulsar gamma rays.

  17. [The applications for Fourier transform infrared spectrum analysis technique in preventive medicine field].

    PubMed

    Yang, Jiao-lan; Luo, Tian

    2002-08-01

    This paper expatriated the applications for Fourier transform infrared spectrum analysis technique in preventive medicine field from four aspects of environmental pollution, life science, and the latest infrared analysis methods and near infrared analysis technique. In the environmental pollution field, it mainly described the advantages, the limitations and the solutions of the combined applications for gas chromatograph and Fourier transform infrared spectrum. In the life science field, it described the application for Fourier transform infrared spectrum analysis technique on protein secondary structure, membrane protein, phospholipid, nucleic acid, cell, tissue. In addition, it also introduced a few latest infrared analysis methods and the applications for near infrared spectrum analysis technique in food, cosmetic, drug.

  18. Analysis of Data from the Transient Gamma-Ray Spectrometer Experiment on the GGS/Wind Spacecraft

    NASA Technical Reports Server (NTRS)

    Hurley, K.

    1997-01-01

    The data analysis from the TGRS experiment is continuing, although the UC Berkeley PI, K. Hurley, is no longer funded for this effort. This experiment has been returning data on the energy spectra and time histories of cosmic gamma-ray bursts since November 1994, and continues to operate in good health. Over a 3 year period ending in November 1997, 41 bursts have been detected simultaneously by TGRS and Dr. Hurley's Ulysses gamma-ray burst experiment. By comparing the times of arrival of a burst at Ulysses and TGRS, we can obtain an annulus of arrival directions for the event. Typical 3sigma annulus widths range from several arcminutes to tens of arcminutes. Because the WIND spacecraft is as far as several light-seconds from Earth, it is sometimes possible to obtain a second annulus using the Burst and Transient Source Experiment (BATSE) aboard the GRO spacecraft. 23 of the 41 bursts were also observed by this experiment. Generally, the two annuli intersect at grazing incidence, leading to a long, narrow error box which reduces somewhat the error circles obtained from BATSE alone. Table 1 summarizes the burst data from TGRS. We plan to defer the publication of these locations until a larger number of events has been accumulated. Measuring the energy spectra of cosmic gamma-ray bursts to search for line emission is one of the prime objectives of this experiment. However, an intense gamma-ray burst is required, or the statistics become too weak to draw meaningful conclusions. One such event has occurred to date, on August 22, 1995, and we have examined it in detail. The spectrum shows no evidence for lines, however.

  19. Modeling daily realized futures volatility with singular spectrum analysis

    NASA Astrophysics Data System (ADS)

    Thomakos, Dimitrios D.; Wang, Tao; Wille, Luc T.

    2002-09-01

    Using singular spectrum analysis (SSA), we model the realized volatility and logarithmic standard deviations of two important futures return series. The realized volatility and logarithmic standard deviations are constructed following the methodology of Andersen et al. [J. Am. Stat. Ass. 96 (2001) 42-55] using intra-day transaction data. We find that SSA decomposes the volatility series quite well and effectively captures both the market trend (accounting for about 34-38% of the total variance in the series) and, more importantly, a number of underlying market periodicities. Reliable identification of any periodicities is extremely important for options pricing and risk management and we believe that SSA can be a useful addition to the financial practitioners’ toolbox.

  20. Performance analysis of spread spectrum modulation in data hiding

    NASA Astrophysics Data System (ADS)

    Gang, Litao; Akansu, Ali N.; Ramkumar, Mahalingam

    2001-12-01

    Watermarking or steganography technology provides a possible solution in digital multimedia copyright protection and pirate tracking. Most of the current data hiding schemes are based on spread spectrum modulation. A small value watermark signal is embedded into the content signal in some watermark domain. The information bits can be extracted via correlation. The schemes are applied both in escrow and oblivious cases. This paper reveals, through analysis and simulation, that in oblivious applications where the original signal is not available, the commonly used correlation detection is not optimal. Its maximum likelihood detection is analyzed and a feasible suboptimal detector is derived. Its performance is explored and compared with the correlation detector. Subsequently a linear embedding scheme is proposed and studied. Experiments with image data hiding demonstrates its effectiveness in applications.

  1. Mutational Spectrum Analysis of Neurodegenerative Diseases and Its Pathogenic Implication.

    PubMed

    Shen, Liang; Ji, Hong-Fang

    2015-10-14

    One of the most conspicuous features of neurodegenerative diseases (NDs) is the occurrence of dramatic conformation change of individual proteins. We performed a mutational spectrum analysis of disease-causing missense mutations in seven types of NDs at nucleotide and amino acid levels, and compared the results with those of non-NDs. The main findings included: (i) The higher mutation ratio of G:C→T:A transversion to G:C→A:T transition was observed in NDs than in non-NDs, interpreting the excessive guanine-specific oxidative DNA damage in NDs; (ii) glycine and proline had highest mutability in NDs than in non-NDs, which favor the protein conformation change in NDs; (iii) surprisingly low mutation frequency of arginine was observed in NDs. These findings help to understand how mutations may cause NDs.

  2. Singular Spectrum Analysis Based on L1-Norm

    NASA Astrophysics Data System (ADS)

    Kalantari, Mahdi; Yarmohammadi, Masoud; Hassani, Hossein

    2016-03-01

    In recent years, the singular spectrum analysis (SSA) technique has been further developed and increasingly applied to solve many practical problems. The aim of this research is to introduce a new version of SSA based on L1-norm. The performance of the proposed approach is assessed by applying it to various real and simulated time series, especially with outliers. The results are compared with those obtained using the basic version of SSA which is based on the Frobenius norm or L2-norm. Different criteria are also examined including reconstruction errors and forecasting performances. The theoretical and empirical results confirm that SSA based on L1-norm can provide better reconstruction and forecasts in comparison to basic SSA when faced with time series which are polluted by outliers.

  3. Reduction of S-parameter errors using singular spectrum analysis

    NASA Astrophysics Data System (ADS)

    Ozturk, Turgut; Uluer, Ihsan; Ünal, Ilhami

    2016-07-01

    A free space measurement method, which consists of two horn antennas, a network analyzer, two frequency extenders, and a sample holder, is used to measure transmission (S21) coefficients in 75-110 GHz (W-Band) frequency range. Singular spectrum analysis method is presented to eliminate the error and noise of raw S21 data after calibration and measurement processes. The proposed model can be applied easily to remove the repeated calibration process for each sample measurement. Hence, smooth, reliable, and accurate data are obtained to determine the dielectric properties of materials. In addition, the dielectric constant of materials (paper, polyvinylchloride-PVC, Ultralam® 3850HT, and glass) is calculated by thin sheet approximation and Newton-Raphson extracting techniques using a filtered S21 transmission parameter.

  4. Reduction of S-parameter errors using singular spectrum analysis.

    PubMed

    Ozturk, Turgut; Uluer, İhsan; Ünal, İlhami

    2016-07-01

    A free space measurement method, which consists of two horn antennas, a network analyzer, two frequency extenders, and a sample holder, is used to measure transmission (S21) coefficients in 75-110 GHz (W-Band) frequency range. Singular spectrum analysis method is presented to eliminate the error and noise of raw S21 data after calibration and measurement processes. The proposed model can be applied easily to remove the repeated calibration process for each sample measurement. Hence, smooth, reliable, and accurate data are obtained to determine the dielectric properties of materials. In addition, the dielectric constant of materials (paper, polyvinylchloride-PVC, Ultralam® 3850HT, and glass) is calculated by thin sheet approximation and Newton-Raphson extracting techniques using a filtered S21 transmission parameter.

  5. Terahertz Spectrum Analysis Based on Empirical Mode Decomposition

    NASA Astrophysics Data System (ADS)

    Su, Yunpeng; Zheng, Xiaoping; Deng, Xiaojiao

    2017-08-01

    Precise identification of terahertz absorption peaks for materials with low concentration and high attenuation still remains a challenge. Empirical mode decomposition was applied to terahertz spectrum analysis in order to improve the performance on spectral fingerprints identification. We conducted experiments on water vapor and carbon monoxide respectively with terahertz time domain spectroscopy. By comparing their absorption spectra before and after empirical mode decomposition, we demonstrated that the first-order intrinsic mode function shows absorption peaks clearly in high-frequency range. By comparing the frequency spectra of the sample signals and their intrinsic mode functions, we proved that the first-order function contains most of the original signal's energy and frequency information so that it cannot be left out or replaced by high-order functions in spectral fingerprints detection. Empirical mode decomposition not only acts as an effective supplementary means to terahertz time-domain spectroscopy but also shows great potential in discrimination of materials and prediction of their concentrations.

  6. The expected high-energy to ultra-high-energy gamma-ray spectrum of the Crab Nebula

    NASA Technical Reports Server (NTRS)

    De Jager, O. C.; Harding, A. K.

    1992-01-01

    The inverse Compton scattering model for the unpulsed TeV emission from the Crab Nebula is reexamined using the magnetic field distribution derived from MHD flow models of the nebula. It is shown that the observed flux can be explained if the average nebular field is indeed about 0.0003, as is predicted by the spectral break between radio and optical. The brightness distribution of the TeV gamma-ray signal is expected to extend out to about 1.5 arcmin from the pulsar. The present estimates predict a steady flux of unpulsed ultrahigh-energy gamma-rays due to the inverse Compton scattering of soft photons by shock-accelerated electrons and/or positrons in the vicinity of the shock.

  7. The expected high-energy to ultra-high-energy gamma-ray spectrum of the Crab Nebula

    NASA Technical Reports Server (NTRS)

    De Jager, O. C.; Harding, A. K.

    1992-01-01

    The inverse Compton scattering model for the unpulsed TeV emission from the Crab Nebula is reexamined using the magnetic field distribution derived from MHD flow models of the nebula. It is shown that the observed flux can be explained if the average nebular field is indeed about 0.0003, as is predicted by the spectral break between radio and optical. The brightness distribution of the TeV gamma-ray signal is expected to extend out to about 1.5 arcmin from the pulsar. The present estimates predict a steady flux of unpulsed ultrahigh-energy gamma-rays due to the inverse Compton scattering of soft photons by shock-accelerated electrons and/or positrons in the vicinity of the shock.

  8. Report on Ultra-high Resolution Gamma- / X-ray Analysis of Uranium Skull Oxide

    SciTech Connect

    Friedrich, S; Velazquez, M; Drury, O; Salaymeh, S

    2009-11-02

    We have utilized the high energy resolution and high peak-to-background ratio of superconducting TES {gamma}-detectors at very low energies for non-destructive analysis of a skull oxide derived from reprocessed nuclear fuel. Specifically, we demonstrate that superconducting detectors can separate and analyze the strong actinide emission lines in the spectral region below 60 keV that are often obscured in {gamma}-measurements with conventional Ge detectors.

  9. Wind speed power spectrum analysis for Bushland, Texas

    SciTech Connect

    Eggleston, E.D.

    1996-12-31

    Numerous papers and publications on wind turbulence have referenced the wind speed spectrum presented by Isaac Van der Hoven in his article entitled Power Spectrum of Horizontal Wind Speed Spectrum in the Frequency Range from 0.0007 to 900 Cycles per Hour. Van der Hoven used data measured at different heights between 91 and 125 meters above the ground, and represented the high frequency end of the spectrum with data from the peak hour of hurricane Connie. These facts suggest we should question the use of his power spectrum in the wind industry. During the USDA - Agricultural Research Service`s investigation of wind/diesel system power storage, using the appropriate wind speed power spectrum became a significant issue. We developed a power spectrum from 13 years of hourly average data, 1 year of 5 minute average data, and 2 particularly gusty day`s 1 second average data all collected at a height of 10 meters. While the general shape is similar to the Van der Hoven spectrum, few of his peaks were found in the Bushland spectrum. While higher average wind speeds tend to suggest higher amplitudes in the high frequency end of the spectrum, this is not always true. Also, the high frequency end of the spectrum is not accurately described by simple wind statistics such as standard deviation and turbulence intensity. 2 refs., 5 figs., 1 tab.

  10. Enhanced lines and box-shaped features in the gamma-ray spectrum from annihilating dark matter in the NMSSM

    SciTech Connect

    Cerdeño, D.G.; Peiró, M.; Robles, S. E-mail: miguel.peiro@uam.es

    2016-04-01

    We study spectral features in the gamma-ray emission from dark matter (DM) annihilation in the Next-to-Minimal Supersymmetric Standard Model (NMSSM), with either neutralino or right-handed (RH) sneutrino DM . We perform a series of scans over the NMSSM parameter space, compute the DM annihilation cross section into two photons and the contribution of box-shaped features, and compare them with the limits derived from the Fermi-LAT search for gamma-ray lines using the latest Pass 8 data. We implement the LHC bounds on the Higgs sector and on the masses of supersymmetric particles as well as the constraints on low-energy observables. We also consider the recent upper limits from the Fermi-LAT satellite on the continuum gamma-ray emission from dwarf spheroidal galaxies (dSphs). We show that in the case of the RH sneutrino the constraint on gamma-ray spectral features can be more stringent than the dSph bounds. This is due to the Breit-Wigner enhancement near the ubiquitous resonances with a CP even Higgs and the contribution of scalar and pseudoscalar Higgs final states to box-shaped features. By contrast, for neutralino DM, the di-photon final state is only enhanced in the resonance with a Z boson and box-shaped features are even more suppressed. Therefore, the observation of spectral features could constitute a discriminating factor between both models. In addition, we compare our results with direct DM searches, including the SuperCDMS and LUX limits on the elastic DM-nucleus scattering cross section and show that some of these scenarios would be accessible to next generation experiments. Thus, our findings strengthen the idea of complementarity among distinct DM search strategies.

  11. Quantification of tissue texture with photoacoustic spectrum analysis

    NASA Astrophysics Data System (ADS)

    Wang, Xueding; Xu, Guan; Meng, Zhuo-Xian; Lin, Jiandie; Carson, Paul

    2014-05-01

    Photoacoustic (PA) imaging is an emerging technology that could map the functional contrasts in deep biological tissues in high resolution by "listening" to the laser induced thermoelastic waves. Almost all of the current studies in PA imaging are focused on the intensity of the PA signals as an indication of the optical absorbance of the biological tissues. Our group has for the first time demonstrated that the frequency domain power distribution of the broadband PA signals encode the texture information within the regions-of-interest (ROI). Following the similar method of ultrasound spectral analysis (USSA), photoacoustic spectrum analysis (PASA) could evaluate the relative concentrations and, more importantly, the dimensions of microstructures of the optically absorbing materials in biological tissues, including lipid, collagen, water and hemoglobin. By providing valuable insights into tissue pathology, PASA should benefit basic research and clinical management of many diseases, and may help achieve eventual "noninvasive biopsy". In this work, taking advantage of the optical absorption contrasts contributed by lipid and hemoglobin at 1200-nm and 532-nm wavelengths respectively, we investigated the capability of PASA in identifying histological changes corresponding to fat accumulation livers through the study on ex vivo and in situ mouse models. The PA signals from the mouse livers were acquired using our PA and US dual-modality imaging system, and analyzed in the frequency domain. After quantifying the power spectrum by fitting it to a first order model, three spectral parameters, including the intercept, the midband fit and the slope, were extracted and used to differentiate fatty livers from normal livers. The comparison between the PASA parameters from the normal and the fatty livers supports our hypotheses that PASA can quantitatively identify the microstructure changes in liver tissues for differentiating normal and fatty livers.

  12. Matrix effects in compositional analysis of bulk materials by PGNAA (prompt gamma/neutron activation analysis). Final report

    SciTech Connect

    Rogers, V.C.; Sandquist, G.M.; Merrell, G.B.; Gozani, T.

    1984-08-01

    This feasibility study has identified and evaluated the influence of important matrix effects which arise in the commercial application of prompt gamma/neutron activation analysis (PGNAA) methods to bulk-coal analysis as follows: neutron moderation and absorption changes; gamma-ray attenuation in the sample; sample density and volume changes. The neutron-induced capture gamma spectra were found to vary in a similar, predictable manner for all neutron absorbers found in coal such as hydrogen, boron, nitrogen, chlorine, and sulfur. Three different models have been proposed from this study to analyze coal by PGNAA methods and account for the significant matrix effects arising from hydrogen variation and other system perturbations.

  13. The Hadronic Origin of the Hard Gamma-Ray Spectrum from Blazar 1ES 1101-232

    NASA Astrophysics Data System (ADS)

    Cao, Gang; Wang, Jiancheng

    2014-03-01

    The very hard γ-ray spectrum from distant blazars challenges the traditional synchrotron self-Compton (SSC) model, which may indicate that there is a contribution from an additional high-energy component beyond the SSC emission. In this paper, we study the possible origin of the hard γ-ray spectrum from distant blazars. We develop a model to explain the hard γ-ray spectrum from blazar 1ES 1101-232. In the model, the optical and X-ray radiation would come from the synchrotron radiation of primary electrons and secondary pairs and the GeV emission would be produced by the SSC process, however, the hard γ-ray spectrum would originate from the decay of neutral pion produced through proton-photon interactions with the synchrotron radiation photons within the jet. Our model can explain the observed spectral energy distribution of 1ES 1101-232 well, especially the very hard γ-ray spectrum. However, our model requires a very large proton power to efficiently produce the γ-ray through proton-photon interactions.

  14. The hadronic origin of the hard gamma-ray spectrum from blazar 1ES 1101-232

    SciTech Connect

    Cao, Gang; Wang, Jiancheng E-mail: jcwang@ynao.ac.cn

    2014-03-10

    The very hard γ-ray spectrum from distant blazars challenges the traditional synchrotron self-Compton (SSC) model, which may indicate that there is a contribution from an additional high-energy component beyond the SSC emission. In this paper, we study the possible origin of the hard γ-ray spectrum from distant blazars. We develop a model to explain the hard γ-ray spectrum from blazar 1ES 1101-232. In the model, the optical and X-ray radiation would come from the synchrotron radiation of primary electrons and secondary pairs and the GeV emission would be produced by the SSC process, however, the hard γ-ray spectrum would originate from the decay of neutral pion produced through proton-photon interactions with the synchrotron radiation photons within the jet. Our model can explain the observed spectral energy distribution of 1ES 1101-232 well, especially the very hard γ-ray spectrum. However, our model requires a very large proton power to efficiently produce the γ-ray through proton-photon interactions.

  15. Phenomenology of prompt gamma neutron activation analysis in the detection of mines and near-surface ordnance

    NASA Astrophysics Data System (ADS)

    Sparrow, David A.; Porter, Lisa J.; Broach, J. Thomas; Mehta-Sherbondy, Roshni J.

    1998-09-01

    Prompt gamma neutron activation analysis (PGNAA) has been proposed for confirming the presence of energetic materials as part of a mine or unexploded ordnance detection system. Ancore Corporation (previously SAIC Advanced Nucleonics Division), funded through Night Vision Electro Sciences Directorate by Environmental Security Test Certification Program, has carried out proof-of-concept demonstrations of PGNAA in this confirmatory role at Socorro, NM, and Yuma, AZ. In this, the first part of a two-part paper addressing the use of PGNAA in the detection of surface and near-surface UXO, we explore the phenomenology of PGNAA signals from surface or near-surface ordnance in soil to gain insight into the results of those demonstrations. PGNAA uses the high-energy gamma ray (10.8 MeV) from capture on N14 as a signature of the presence of nitrogen. This is one of the highest energy gamma rays resulting from neutron capture, and nitrogen is a major constituent of explosives, but a small portion of soil. Thus, PGNAA might be effective at confirming the presence of explosives. The phenomenology of dry soil is dominated by the two most common elements, oxygen and silicon. Neutrons injected into the soil elastically scatter from nuclei (predominantly oxygen), losing energy and propagating in a random walk fashion. Once slowed, neutron capture on soil elements produces a broad gamma-ray spectrum. Capture on Si29 produces a 10.6 MeV gamma, which is not resolvable from the nitrogen signal of interest using scintillation detectors. Thus, PGNAA will need either good resolution detectors, or robust background subtraction to estimate the silicon contribution. For any system unable to resolve the Si29 (10.6 MeV) and N14(10.8 MeV) gammas there is an inherently low signal to background, resulting primarily from the silicon in the soil. After background subtraction, there remains a challenging signal to noise level, where the noise is partly due to counting statistics and partly due to the

  16. Prompt gamma ray evaluation for chlorine analysis in blended cement concrete.

    PubMed

    Naqvi, A A; Maslehuddin, M; Kalakada, Zameer; Al-Amoudi, O S B

    2014-12-01

    Single prompt gamma ray energy has been evaluated to measure chlorine concentration in fly ash (FA), Super-Pozz (SPZ) and blast furnace slag (BFS) cement concrete specimens using a portable neutron generator-based Prompt Gamma Neutron Activation (PGNAA) setup. The gamma ray yield data from chloride concentration measurement in FA, SPZ and BFS cement concretes for 2.86-3.10, 5.72 and 6.11MeV chlorine gamma rays were analyzed to identify a gamma ray with common slope (gamma ray yield/Cl conc. wt%) for the FA, BFS and SPZ cement concretes. The gamma ray yield data for FA and SPZ cement concretes with varying chloride concentration were measured previously using a portable neutron generator-based PGNAA setup. In the current study, new data have been measured for chlorine detection in the BFS cement concrete using a portable neutron generator-based PGNAA setup for 2.86-3.10, 5.72, and 6.11MeV chlorine gamma rays. The minimum detection limit of chlorine in BFS cement concrete (MDC) was found to be 0.034±0.010, 0.032±0.010, 0.033±0.010 for 2.86-3.10, 5.72 and 6.11MeV gamma ray, respectively. The new BFS cement concrete data, along with the previous measurements for FA and SPZ cement concretes, have been utilized to identify a gamma ray with a common slope to analyze the Cl concentration in all of these blended cement concretes. It has been observed that the 6.11MeV chlorine gamma ray has a common slope of 5295±265 gamma rays/wt % Cl concentration for the portable neutron generator-based PGNAA setup. The minimum detectable concentration (MDC) of chlorine in blended cement concrete was measured to be 0.033±0.010wt % for the portable neutron generator-based PGNAA. Thus, the 6.11MeV chlorine gamma ray can be used for chlorine analysis of blended cement concretes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Analysis of the Swift Gamma-Ray Bursts duration

    SciTech Connect

    Horvath, I.; Veres, P.; Balazs, L. G.; Kelemen, J.; Bagoly, Z.

    2008-10-22

    Two classes of gamma-ray bursts have been identified in the BATSE catalogs characterized by durations shorter and longer than about 2 seconds. There are, however, some indications for the existence of a third type of burst. Swift satellite detectors have different spectral sensitivity than pre-Swift ones for gamma-ray bursts. Therefore it is worth to reanalyze the durations and their distribution and also the classification of GRBs. Using The First BAT Catalog the maximum likelihood estimation was used to analyzed the duration distribution of GRBs. The three log-normal fit is significantly (99.54% probability) better than the two for the duration distribution. Monte-Carlo simulations also confirm this probability (99.2%)

  18. Gamma Detector Response and Analysis Software - Detector Response Function

    SciTech Connect

    2014-05-13

    GADRAS-DRF uses a Detector Response Function (DRF) to compute the response of gamma-ray detectors incident radiation. The application includes provision for plotting measured and computed spectra and for characterizing detector response parameters based on measurements of a series of calibration sources (e.g., Ba-133, Cs-137, Co-60, and Th-228). An application program interface enables other programs to access the dynamic-link library that is used to compute spectra.

  19. c-GAMMA:Comparative Genome Analysis of Molecular Markers

    NASA Astrophysics Data System (ADS)

    Peterlongo, Pierre; Nicolas, Jacques; Lavenier, Dominique; Vorc'h, Raoul; Querellou, Joël

    Discovery of molecular markers for efficient identification of living organisms remains a challenge of high interest. The diversity of species can now be observed in details with low cost genomic sequences produced by new generation of sequencers. A method, called c-GAMMA, is proposed. It formalizes the design of new markers for such data. It is based on a series of filters on forbidden pairs of words, followed by an optimization step on the discriminative power of candidate markers.

  20. Corrections for volume hydrogen content in coal analysis by prompt gamma neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Salgado, J.; Oliveira, C.

    1992-05-01

    Prompt gamma neutron activation analysis, PGNAA, is a useful technique to determine the elemental composition of bulk samples in on-line measurements. Monte Carlo simulation studies performed in bulk coals of different compositions for given sample size and geometry have shown that both the gamma count rate for hydrogen and the gamma count rate per percent by weight for an arbitrary element due to (n, γ) reactions depend on the volume hydrogen content, being independent of coal composition. Experimental results using a 252Cf neutron source surrounded by a lead cylinder were obtained for nine different coal types. These show that the γ-peak originated by (n, n' γ) reactions in the lead shield depends on the sample density. Assuming that the source intensity is constant, this result enables the measurement of the coal bulk density. Taking into account the results just described, the present paper shows how the γ-peak intensities can be corrected for volume hydrogen content in order to obtain the percent by weight contents of the coal. The density is necessary to convert the volume hydrogen in percent by weight content and to calculate the bulk sample weight.

  1. Frequency spectrum analysis of finger photoplethysmographic waveform variability during haemodialysis.

    PubMed

    Javed, Faizan; Middleton, Paul M; Malouf, Philip; Chan, Gregory S H; Savkin, Andrey V; Lovell, Nigel H; Steel, Elizabeth; Mackie, James

    2010-09-01

    This study investigates the peripheral circulatory and autonomic response to volume withdrawal in haemodialysis based on spectral analysis of photoplethysmographic waveform variability (PPGV). Frequency spectrum analysis was performed on the baseline and pulse amplitude variabilities of the finger infrared photoplethysmographic (PPG) waveform and on heart rate variability extracted from the ECG signal collected from 18 kidney failure patients undergoing haemodialysis. Spectral powers were calculated from the low frequency (LF, 0.04-0.145 Hz) and high frequency (HF, 0.145-0.45 Hz) bands. In eight stable fluid overloaded patients (fluid removal of >2 L) not on alpha blockers, progressive reduction in relative blood volume during haemodialysis resulted in significant increase in LF and HF powers of PPG baseline and amplitude variability (P < 0.01), when expressed in mean-scaled units. The augmentation of LF powers in PPGV during haemodialysis may indicate the recovery and possibly further enhancement of peripheral sympathetic vascular modulation subsequent to volume unloading, whilst the increase in respiratory HF power in PPGV is most likely a sign of preload reduction. Spectral analysis of finger PPGV may provide valuable information on the autonomic vascular response to blood volume reduction in haemodialysis, and can be potentially utilized as a non-invasive tool for assessing peripheral circulatory control during routine dialysis procedure.

  2. Blind Extraction of an Exoplanetary Spectrum through Independent Component Analysis

    NASA Astrophysics Data System (ADS)

    Waldmann, I. P.; Tinetti, G.; Deroo, P.; Hollis, M. D. J.; Yurchenko, S. N.; Tennyson, J.

    2013-03-01

    Blind-source separation techniques are used to extract the transmission spectrum of the hot-Jupiter HD189733b recorded by the Hubble/NICMOS instrument. Such a "blind" analysis of the data is based on the concept of independent component analysis. The detrending of Hubble/NICMOS data using the sole assumption that nongaussian systematic noise is statistically independent from the desired light-curve signals is presented. By not assuming any prior or auxiliary information but the data themselves, it is shown that spectroscopic errors only about 10%-30% larger than parametric methods can be obtained for 11 spectral bins with bin sizes of ~0.09 μm. This represents a reasonable trade-off between a higher degree of objectivity for the non-parametric methods and smaller standard errors for the parametric de-trending. Results are discussed in light of previous analyses published in the literature. The fact that three very different analysis techniques yield comparable spectra is a strong indication of the stability of these results.

  3. Evaluating Acupuncture Point and Nonacupuncture Point Stimulation with EEG: A High-Frequency Power Spectrum Analysis

    PubMed Central

    Choi, Kwang-Ho; Cho, Seong Jin; Kang, Suk-Yun; Ahn, Seong Hun

    2016-01-01

    To identify physical and sensory responses to acupuncture point stimulation (APS), nonacupuncture point stimulation (NAPS) and no stimulation (NS), changes in the high-frequency power spectrum before and after stimulation were evaluated with electroencephalography (EEG). A total of 37 healthy subjects received APS at the LI4 point, NAPS, or NS with their eyes closed. Background brain waves were measured before, during, and after stimulation using 8 channels. Changes in the power spectra of gamma waves and high beta waves before, during, and after stimulation were comparatively analyzed. After NAPS, absolute high beta power (AHBP), relative high beta power (RHBP), absolute gamma power (AGP), and relative gamma power (RGP) tended to increase in all channels. But no consistent notable changes were found for APS and NS. NAPS is believed to cause temporary reactions to stress, tension, and sensory responses of the human body, while APS responds stably compared to stimulation of other parts of the body. PMID:27818695

  4. Analysis of gamma prime shape changes in a single crystal Ni-base superalloy

    NASA Technical Reports Server (NTRS)

    Gayda, J.; Mackay, R. A.

    1989-01-01

    The microstructural evolution of a commercial single crystal superalloy, NASAIR 100, is analyzed using the existing high-temperature lattice mismatch data and high-temperature moduli obtained from tests on single crystals of gamma and gamma prime. A multiparticle analysis of the microstructural evolution is performed using a novel microstructural lattice simulation technique, MCFET. Under a uniaxial stress, a regular array of gamma prime particles in the simulated microstructure is predicted to coalesce and form a plate morphology, with the broad faces of the plates and stress axis perpendicular in tension but parallel in compression. These results are consistent with changes in gamma prime shape observed in NASAIR 100 following creep testing at 1000 C.

  5. The Monte Carlo code CEARCPG for coincidence prompt gamma-ray neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Han, Xiaogang; Gardner, Robin P.

    2007-10-01

    Prompt gamma-ray neutron activation analysis (PGNAA) is widely used to determine the elemental composition of bulk samples. The detection sensitivities of PGNAA are often restricted by the inherent poor signal-to-noise ratio (SNR). There are many sources of noise (background) including the natural background, neutron activation of the detector, gamma-rays associated with the neutron source and prompt gamma-rays from the structural materials of the analyzer. Results of the prompt gamma-ray coincidence technique show that it could greatly improve the SNR by removing almost all of the background interferences. The first specific Monte Carlo code (CEARCPG) for coincidence PGNAA has been developed at the Center for Engineering Application of Radioisotopes (CEAR) to explore the capabilities of this technique. Benchmark bulk sample experiments have been performed with coal, sulfur, and mercury samples and indicate that the code is accurate and will be very useful in the design of coincidence PGNAA devices.

  6. A new gamma-ray detector, 3-dimension, fast scanning table for pulse-shape analysis

    SciTech Connect

    Ginsz, M.; Duchene, G.; Didierjean, F.; Filliger, M.; Sigward, M.-H.; Pirard, B.

    2015-07-01

    The state-of-the art gamma-ray spectrometers such as AGATA and GRETA are using position sensitive multi-segmented HPGe crystals. Pulse-shape analysis (PSA) allows to retrieve the localisation of the gamma interactions and to perform gamma-ray tracking within germanium. The precision of the localisation depends on the quality of the pulse-shape database used for comparison. The IPHC laboratory developed a new fast scanning table allowing to measure experimental pulse shapes in the whole volume of any crystal. The results of the scan of an AGATA 36-fold segmented tapered coaxial detector are shown here, 48580 experimental pulse shapes are extracted within 2 weeks of scanning. These data will contribute to AGATA PSA performances, but have also applications for gamma cameras or Compton-suppressed detectors. (authors)

  7. The Marshall Space Flight Center Development of Mirror Modules for the ART-XC Instrument aboard the Spectrum-Roentgen-Gamma Mission

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail V.; Ramsey, B.; ODell, S. L.; Elsner, R.; Kilaru, K.; McCracken, J.; Pavlinsky, M.; Tkachenko, A.; Lapshov, I.

    2012-01-01

    The Marshall Space Flight Center (MSFC) is developing x-ray mirror modules for the ART-XC instrument on board the Spectrum-Roentgen Gamma Mission under a Reimbursable Agreement between NASA and the Russian Space Research Institute (IKI.) ART-XC will consist of seven co-aligned x-ray mirror modules with seven corresponding CdTe focal plane detectors. Currently, four of the modules are being fabricated by the Marshall Space Flight Center (MSFC.) Each MSFC module consist of 28 nested Ni/Co thin shells giving an effective area of 65 sq cm at 8 keV, response out to 30 keV, and an angular resolution of 45 arcsec or better HPD. Delivery of these modules to the IKI is scheduled for summer 2013. We present a status of the ART x-ray modules development at the MSFC.

  8. The Marshall Space Flight Center Development of Mirror Modules for the ART-XC Ins1rument Aboard the Spectrum-Roentgen-Gamma Mission

    NASA Technical Reports Server (NTRS)

    Gubarev, M.; Ramsey, B.; ODell, S. L.; Elsner, R.; Kilaru, K.; McCracken, J.; Pavlinsky, M.; Tkachenko, A.; Lapshov, I.

    2012-01-01

    The Spectrum-Rontgen-Gamma (SRG) mission is a Russian-German X-ray astrophysical observatory that carries two co-aligned and complementary X-ray telescope systems. The primary instrument is the German-led extended ROentgen Survey with an Imaging Telescope Array (eROSITA), a 7-module X-ray telescope system that covers the energy range from 0.2-12 keV. The complementary instrument is the Russian-led Astronomical Roentgen Telescope -- X-ray Concentrator (ART-XC or ART), a 7-module X-ray telescope system that provides higher energy coverage, up to 30 keV (with limited sensitivity above 12 keV).

  9. The Marshall Space Flight Center development of mirror modules for the ART-XC instrument aboard the Spectrum-Roentgen-Gamma mission

    NASA Astrophysics Data System (ADS)

    Gubarev, M.; Ramsey, B.; O'Dell, S. L.; Elsner, R.; Kilaru, K.; McCracken, J.; Pavlinsky, M.; Tkachenko, A.; Lapshov, I.

    2012-09-01

    The Marshall Space Flight Center (MSFC) is developing x-ray mirror modules for the ART-XC instrument on board the Spectrum-Roentgen-Gamma Mission under a Reimbursable Agreement between NASA and the Russian Space Research Institute (IKI.) ART-XC will consist of seven co-aligned x-ray mirror modules with seven corresponding CdTe focal plane detectors. Currently, four of the modules are being fabricated by the Marshall Space Flight Center (MSFC.) Each MSFC module consist of 28 nested Ni/Co thin shells giving an effective area of 65 cm2 at 8 keV, response out to 30 keV, and an angular resolution of 45 arcsec or better HPD. Delivery of these modules to the IKI is scheduled for summer 2013. We present a status of the ART x-ray modules development at the MSFC.

  10. Power spectrum analysis for defect screening in integrated circuit devices

    DOEpatents

    Tangyunyong, Paiboon; Cole Jr., Edward I.; Stein, David J.

    2011-12-01

    A device sample is screened for defects using its power spectrum in response to a dynamic stimulus. The device sample receives a time-varying electrical signal. The power spectrum of the device sample is measured at one of the pins of the device sample. A defect in the device sample can be identified based on results of comparing the power spectrum with one or more power spectra of the device that have a known defect status.

  11. Analysis of Data from the Balloon Borne Gamma RAy Polarimeter Experiment (GRAPE)

    NASA Astrophysics Data System (ADS)

    Wasti, Sambid K.; Bloser, Peter F.; Legere, Jason S.; McConnell, Mark L.; Ryan, James M.

    2016-04-01

    The Gamma Ray Polarimeter Experiment (GRAPE), a balloon borne polarimeter for 50~300 keV gamma rays, successfully flew in 2011 and 2014. The main goal of these balloon flights was to measure the gamma ray polarization of the Crab Nebula. Analysis of data from the first two balloon flights of GRAPE has been challenging due to significant changes in the background level during each flight. We have developed a technique based on the Principle Component Analysis (PCA) to estimate the background for the Crab observation. We found that the background depended mostly on the atmospheric depth, pointing zenith angle and instrument temperatures. Incorporating Anti-coincidence shield data (which served as a surrogate for the background) was also found to improve the analysis. Here, we present the calibration data and describe the analysis done on the GRAPE 2014 flight data.

  12. GAMMA: a code for the analysis of component failure rates with a compound Poisson-gamma model. Final technical report

    SciTech Connect

    Shultis, J.K.; Johnson, D.E.; Milliken, G.A.; Eckhoff, N.D.

    1981-12-01

    The theory is summarized for the homogeneous Poisson and the compound gamma-Poisson probability models which can be used to analyze failure rate attribute data consisting of the number of failures in specified test times for normally operating components or systems. A computer code based on this theory is described, and instructions for its use together with a sample problem and a complete code listing are presented. For the compound model, used in a Bayesian analysis of failure rate data, values of the parameters for the prior gamma distribution, chosen a priori, are estimated from observed failure data by three methods: (1) matching the data moments to those of the prior distribution, (2) matching the data moments to those of the marginal distribution, and (3) the marginal maximum likelihood method. Many program options are available including variance estimates for the prior parameter estimators, posteriori analyses for each component, various statistical comparisons between the homogeneous and compound models, and generalized chi-square and Kolmogorov-Smirnov goodness-of-fit tests for determining how well the failure models describe the observed data.

  13. Performance analysis of free space optical system with spatial modulation and diversity combiners over the Gamma Gamma atmospheric turbulence

    NASA Astrophysics Data System (ADS)

    Odeyemi, Kehinde O.; Owolawi, Pius A.; Srivastava, Viranjay M.

    2017-01-01

    Atmospheric turbulence is a major impairment that degrades the performance of free space optical (FSO) communication systems. Spatial modulation (SM) with receive spatial diversity is considered as a powerful technique to mitigate the fading effect induced by atmospheric turbulence. In this paper, the performance of free space optical spatial modulation (FSO-SM) system under Gamma-Gamma atmospheric turbulence is presented. We studied the Average Bit Error Rate (ABER) for the system by employing spatial diversity combiners such Maximum Ratio Combining (MRC) and Equal Gain Combining (EGC) at the receiving end. In particular, we provide a theoretical framework for the system error by deriving Average Pairwise Error Probability (APEP) expression using a generalized infinite power series expansion approach and union bounding technique is applied to obtain the ABER for each combiner. Based on this study, it was found that spatial diversity combiner significantly improved the system error rate where MRC outperforms the EGC. The performance of this system is also compared with other well established diversity combiner systems. The proposed system performance is further improved by convolutional coding technique and our analysis confirmed that the system performance of MRC coded system is enhanced by approximately 20 dB while EGC falls within 17 dB.

  14. Theoretical analysis of spectrum flattening in fiber laser oscillator

    NASA Astrophysics Data System (ADS)

    Shi, Chen; Wang, Xiaolin; Zhou, Pu; Wang, Zefeng; Xu, Xiaojun; Lu, Qisheng

    2017-01-01

    The flatness of laser spectrum is important in many applications. In this manuscript, a method of acquiring flattened spectrum directly from a fiber oscillator by optimizing the reflective spectrum of Fiber Bragg Gratings (FBG) was demonstrated and optimized result at wavelength around 1064 nm and 1080 nm was presented. An optimization path to alter the reflectivity of FBGs using greedy algorithm was interpreted by analyzing the single-trip gain inside the resonant cavity. Our method has a guiding significance of controlling the output spectrum of laser oscillator using FBGs.

  15. Features in the primordial spectrum from WMAP: A wavelet analysis

    SciTech Connect

    Shafieloo, Arman; Souradeep, Tarun; Manimaran, P.; Panigrahi, Prasanta K.; Rangarajan, Raghavan

    2007-06-15

    Precise measurements of the anisotropies in the cosmic microwave background enable us to do an accurate study on the form of the primordial power spectrum for a given set of cosmological parameters. In a previous paper [A. Shafieloo and T. Souradeep, Phys. Rev. D 70, 043523 (2004).], we implemented an improved (error sensitive) Richardson-Lucy deconvolution algorithm on the measured angular power spectrum from the first year of WMAP data to determine the primordial power spectrum assuming a concordance cosmological model. This recovered spectrum has a likelihood far better than a scale invariant, or, 'best fit' scale free spectra ({delta}lnL{approx_equal}25 with respect to the Harrison-Zeldovich spectrum, and, {delta}lnL{approx_equal}11 with respect to the power law spectrum with n{sub s}=0.95). In this paper we use the discrete wavelet transform (DWT) to decompose the local features of the recovered spectrum individually to study their effect and significance on the recovered angular power spectrum and hence the likelihood. We show that besides the infrared cutoff at the horizon scale, the associated features of the primordial power spectrum around the horizon have a significant effect on improving the likelihood. The strong features are localized at the horizon scale.

  16. Future Prospects for Space-Based Gamma Ray Astronomy

    NASA Astrophysics Data System (ADS)

    McConnell, Mark

    2015-04-01

    The gamma-ray sky offers a unique view into broad range of astrophysical phenomena, from nearby solar flares, to galactic pulsars, to gamma-ray bursts at the furthest reaches of the Universe. The Fermi mission has dramatically demonstrated the broad range of topics that can be addressed by gamma-ray observations. The full range of gamma-ray energies is quite broad, covering the electromagnetic spectrum at energies above about 100 keV. The energy range below several hundred GeV is the domain of space-based gamma-ray observatories, a range that is not completely covered by the Fermi LAT instrument. The gamma ray community has recently embarked on an effort to define the next steps for space-based gamma ray astronomy. These discussions are being facilitated through the Gamma-ray Science Interest Group (GammaSIG), which exists to provide community input to NASA in regards to current and future needs of the gamma-ray astrophysics community. The GammaSIG, as a part of the Physics of the Cosmos Program Analysis Group, provides a forum open to all members of the gamma-ray community. The GammaSIG is currently working to bring the community together with a common vision that will be expressed in the form of a community roadmap. This talk will summarize some of the latest results from active gamma ray observatories, including both Fermi and INTEGRAL, and will summarize the status of the community roadmap effort.

  17. A LINGERING NON-THERMAL COMPONENT IN THE GAMMA-RAY BURST PROMPT EMISSION: PREDICTING GeV EMISSION FROM THE MeV SPECTRUM

    SciTech Connect

    Basak, Rupal; Rao, A. R. E-mail: arrao@tifr.res.in

    2013-09-20

    The high-energy GeV emission of gamma-ray bursts (GRBs) detected by Fermi/LAT has a significantly different morphology compared to the lower energy MeV emission detected by Fermi/GBM. Though the late-time GeV emission is believed to be synchrotron radiation produced via an external shock, this emission as early as the prompt phase is puzzling. A meaningful connection between these two emissions can be drawn only by an accurate description of the prompt MeV spectrum. We perform a time-resolved spectroscopy of the Gamma-ray Burst Monitor (GBM) data of long GRBs with significant GeV emission, using a model consisting of two blackbodies and a power law. We examine in detail the evolution of the spectral components and find that GRBs with high GeV emission (GRB 090902B and GRB 090926A) have a delayed onset of the power-law component in the GBM spectrum, which lingers at the later part of the prompt emission. This behavior mimics the flux evolution in the Large Area Telescope (LAT). In contrast, bright GBM GRBs with an order of magnitude lower GeV emission (GRB 100724B and GRB 091003) show a coupled variability of the total and the power-law flux. Further, by analyzing the data for a set of 17 GRBs, we find a strong correlation between the power-law fluence in the MeV and the LAT fluence (Pearson correlation: r = 0.88 and Spearman correlation: ρ = 0.81). We demonstrate that this correlation is not influenced by the correlation between the total and the power-law fluences at a confidence level of 2.3σ. We speculate the possible radiation mechanisms responsible for the correlation.

  18. A Lingering Non-thermal Component in the Gamma-Ray Burst Prompt Emission: Predicting GeV Emission from the MeV Spectrum

    NASA Astrophysics Data System (ADS)

    Basak, Rupal; Rao, A. R.

    2013-09-01

    The high-energy GeV emission of gamma-ray bursts (GRBs) detected by Fermi/LAT has a significantly different morphology compared to the lower energy MeV emission detected by Fermi/GBM. Though the late-time GeV emission is believed to be synchrotron radiation produced via an external shock, this emission as early as the prompt phase is puzzling. A meaningful connection between these two emissions can be drawn only by an accurate description of the prompt MeV spectrum. We perform a time-resolved spectroscopy of the Gamma-ray Burst Monitor (GBM) data of long GRBs with significant GeV emission, using a model consisting of two blackbodies and a power law. We examine in detail the evolution of the spectral components and find that GRBs with high GeV emission (GRB 090902B and GRB 090926A) have a delayed onset of the power-law component in the GBM spectrum, which lingers at the later part of the prompt emission. This behavior mimics the flux evolution in the Large Area Telescope (LAT). In contrast, bright GBM GRBs with an order of magnitude lower GeV emission (GRB 100724B and GRB 091003) show a coupled variability of the total and the power-law flux. Further, by analyzing the data for a set of 17 GRBs, we find a strong correlation between the power-law fluence in the MeV and the LAT fluence (Pearson correlation: r = 0.88 and Spearman correlation: ρ = 0.81). We demonstrate that this correlation is not influenced by the correlation between the total and the power-law fluences at a confidence level of 2.3σ. We speculate the possible radiation mechanisms responsible for the correlation.

  19. Temporal Evolution of the Gamma-ray Burst Afterglow Spectrum for an Observer: GeV-TeV Synchrotron Self-Compton Light Curve

    NASA Astrophysics Data System (ADS)

    Fukushima, Takuma; To, Sho; Asano, Katsuaki; Fujita, Yutaka

    2017-08-01

    We numerically simulate the gamma-ray burst (GRB) afterglow emission with a one-zone time-dependent code. The temporal evolutions of the decelerating shocked shell and energy distributions of electrons and photons are consistently calculated. The photon spectrum and light curves for an observer are obtained taking into account the relativistic propagation of the shocked shell and the curvature of the emission surface. We find that the onset time of the afterglow is significantly earlier than the previous analytical estimate. The analytical formulae of the shock propagation and light curve for the radiative case are also different from our results. Our results show that even if the emission mechanism is switching from synchrotron to synchrotron self-Compton, the gamma-ray light curves can be a smooth power law, which agrees with the observed light curve and the late detection of a 32 GeV photon in GRB 130427A. The uncertainty of the model parameters obtained with the analytical formula is discussed, especially in connection with the closure relation between spectral index and decay index.

  20. Improved singular spectrum analysis for time series with missing data

    NASA Astrophysics Data System (ADS)

    Shen, Y.; Peng, F.; Li, B.

    2015-07-01

    Singular spectrum analysis (SSA) is a powerful technique for time series analysis. Based on the property that the original time series can be reproduced from its principal components, this contribution develops an improved SSA (ISSA) for processing the incomplete time series and the modified SSA (SSAM) of Schoellhamer (2001) is its special case. The approach is evaluated with the synthetic and real incomplete time series data of suspended-sediment concentration from San Francisco Bay. The result from the synthetic time series with missing data shows that the relative errors of the principal components reconstructed by ISSA are much smaller than those reconstructed by SSAM. Moreover, when the percentage of the missing data over the whole time series reaches 60 %, the improvements of relative errors are up to 19.64, 41.34, 23.27 and 50.30 % for the first four principal components, respectively. Both the mean absolute error and mean root mean squared error of the reconstructed time series by ISSA are also smaller than those by SSAM. The respective improvements are 34.45 and 33.91 % when the missing data accounts for 60 %. The results from real incomplete time series also show that the standard deviation (SD) derived by ISSA is 12.27 mg L-1, smaller than the 13.48 mg L-1 derived by SSAM.

  1. Improved singular spectrum analysis for time series with missing data

    NASA Astrophysics Data System (ADS)

    Shen, Y.; Peng, F.; Li, B.

    2014-12-01

    Singular spectrum analysis (SSA) is a powerful technique for time series analysis. Based on the property that the original time series can be reproduced from its principal components, this contribution will develop an improved SSA (ISSA) for processing the incomplete time series and the modified SSA (SSAM) of Schoellhamer (2001) is its special case. The approach was evaluated with the synthetic and real incomplete time series data of suspended-sediment concentration from San Francisco Bay. The result from the synthetic time series with missing data shows that the relative errors of the principal components reconstructed by ISSA are much smaller than those reconstructed by SSAM. Moreover, when the percentage of the missing data over the whole time series reaches 60%, the improvements of relative errors are up to 19.64, 41.34, 23.27 and 50.30% for the first four principal components, respectively. Besides, both the mean absolute errors and mean root mean squared errors of the reconstructed time series by ISSA are also much smaller than those by SSAM. The respective improvements are 34.45 and 33.91% when the missing data accounts for 60%. The results from real incomplete time series also show that the SD derived by ISSA is 12.27 mg L-1, smaller than 13.48 mg L-1 derived by SSAM.

  2. Characterization of bone microstructure using photoacoustic spectrum analysis

    NASA Astrophysics Data System (ADS)

    Feng, Ting; Kozloff, Kenneth M.; Xu, Guan; Du, Sidan; Yuan, Jie; Deng, Cheri X.; Wang, Xueding

    2015-03-01

    Osteoporosis is a progressive bone disease that is characterized by a decrease in bone mass and deterioration in microarchitecture. This study investigates the feasibility of characterizing bone microstructure by analyzing the frequency spectrum of the photoacoustic signals from the bone. Modeling and numerical simulation of photoacoustic signals and their frequency-domain analysis were performed on trabecular bones with different mineral densities. The resulting quasilinear photoacoustic spectra were fit by linear regression, from which spectral parameter slope can be quantified. The modeling demonstrates that, at an optical wavelength of 685 nm, bone specimens with lower mineral densities have higher slope. Preliminary experiment on osteoporosis rat tibia bones with different mineral contents has also been conducted. The finding from the experiment has a good agreement with the modeling, both demonstrating that the frequency-domain analysis of photoacoustic signals can provide objective assessment of bone microstructure and deterioration. Considering that photoacoustic measurement is non-ionizing, non-invasive, and has sufficient penetration in both calcified and noncalcified tissues, this new technology holds unique potential for clinical translation.

  3. Characterization of bone microstructure using photoacoustic spectrum analysis

    PubMed Central

    Feng, Ting; Perosky, Joseph E.; Kozloff, Kenneth M.; Xu, Guan; Cheng, Qian; Du, Sidan; Yuan, Jie; Deng, Cheri X.; Wang, Xueding

    2015-01-01

    Osteoporosis is a progressive bone disease that is characterized by a decrease in bone mass and the deterioration in bone microarchitecture. This study investigates the feasibility of characterizing bone microstructure by analyzing the frequency spectrum of the photoacoustic (PA) signal from the bone. Modeling and numerical simulation of PA signal were performed on trabecular bone simulations and CT scans with different trabecular thicknesses. The resulting quasi-linear photoacoustic spectra were fittted by linear regression, from which the spectral parameter slope was quantified. The simulation based on two different models both demonstrate that bone specimens with thinner trabecular thicknesses have higher slope. Experiment on osteoporotic rat femoral heads with different mineral content was conducted. The finding from the experiment was in good agreement with the simulation, demonstrating that the frequency-domain analysis of PA signals can provide an objective assessment of bone microstructure and deterioration. Considering that PA measurement is non-ionizing, non-invasive, and has sufficient penetration in both calcified and non-calcified tissues, this new bone evaluation method based on photoacoustic spectral analysis holds potential for clinical management of osteoporosis and other bone diseases. PMID:26406719

  4. Localizing Microaneurysms in Fundus Images Through Singular Spectrum Analysis.

    PubMed

    Wang, Su; Tang, Hongying Lilian; Al Turk, Lutfiah Ismail; Hu, Yin; Sanei, Saeid; Saleh, George Michael; Peto, Tunde

    2017-05-01

    Reliable recognition of microaneurysms (MAs) is an essential task when developing an automated analysis system for diabetic retinopathy (DR) detection. In this study, we propose an integrated approach for automated MA detection with high accuracy. Candidate objects are first located by applying a dark object filtering process. Their cross-section profiles along multiple directions are processed through singular spectrum analysis. The correlation coefficient between each processed profile and a typical MA profile is measured and used as a scale factor to adjust the shape of the candidate profile. This is to increase the difference in their profiles between true MAs and other non-MA candidates. A set of statistical features of those profiles is then extracted for a K-nearest neighbor classifier. Experiments show that by applying this process, MAs can be separated well from the retinal background, the most common interfering objects and artifacts. The results have demonstrated the robustness of the approach when testing on large scale datasets with clinically acceptable sensitivity and specificity. The approach proposed in the evaluated system has great potential when used in an automated DR screening tool or for large scale eye epidemiology studies.

  5. Characterization of bone microstructure using photoacoustic spectrum analysis.

    PubMed

    Feng, Ting; Perosky, Joseph E; Kozloff, Kenneth M; Xu, Guan; Cheng, Qian; Du, Sidan; Yuan, Jie; Deng, Cheri X; Wang, Xueding

    2015-09-21

    Osteoporosis is a progressive bone disease that is characterized by a decrease in bone mass and the deterioration in bone microarchitecture. This study investigates the feasibility of characterizing bone microstructure by analyzing the frequency spectrum of the photoacoustic (PA) signal from the bone. Modeling and numerical simulation of PA signal were performed on trabecular bone simulations and CT scans with different trabecular thicknesses. The resulting quasi-linear photoacoustic spectra were fittted by linear regression, from which the spectral parameter slope was quantified. The simulation based on two different models both demonstrate that bone specimens with thinner trabecular thicknesses have higher slope. Experiment on osteoporotic rat femoral heads with different mineral content was conducted. The finding from the experiment was in good agreement with the simulation, demonstrating that the frequency-domain analysis of PA signals can provide an objective assessment of bone microstructure and deterioration. Considering that PA measurement is non-ionizing, non-invasive, and has sufficient penetration in both calcified and non-calcified tissues, this new bone evaluation method based on photoacoustic spectral analysis holds potential for clinical management of osteoporosis and other bone diseases.

  6. Localizing heart sounds in respiratory signals using singular spectrum analysis.

    PubMed

    Ghaderi, Foad; Mohseni, Hamid R; Sanei, Saeid

    2011-12-01

    Respiratory sounds are always contaminated by heart sound interference. An essential preprocessing step in some of the heart sound cancellation methods is localizing primary heart sound components. Singular spectrum analysis (SSA), a powerful time series analysis technique, is used in this paper. Despite the frequency overlap of the heart and lung sound components, two different trends in the eigenvalue spectra are recognizable, which leads to find a subspace that contains more information about the underlying heart sound. Artificially mixed and real respiratory signals are used for evaluating the performance of the method. Selecting the appropriate length for the SSA window results in good decomposition quality and low computational cost for the algorithm. The results of the proposed method are compared with those of well-established methods, which use the wavelet transform and entropy of the signal to detect the heart sound components. The proposed method outperforms the wavelet-based method in terms of false detection and also correlation with the underlying heart sounds. Performance of the proposed method is slightly better than that of the entropy-based method. Moreover, the execution time of the former is significantly lower than that of the latter.

  7. Development and analysis for core power gamma thermometer adaptation

    SciTech Connect

    Ren-Tai Chiang; Leong, T.

    1996-12-31

    The gamma thermometer (GT) has gained increasing interest to replace the local power range monitor (LPRM) and the traversing in-core probe (TIP) as the core monitoring device in new boiling water reactor (BWR) designs. The number of GTs is designed between the number of LPRMs, 4, and the number of TIPs, 24, per string, but its optimal number is yet to be determined. The authors have modified the BWR core Simulator PANACEA for analyzing the core power GT adaptation and have compared the axial core-averaged relative power distributions and two thermal limits of the GT 8- and 12-point adaptations against those of the TIP 24-point adaptation.

  8. Analysis of gamma-ray burst spectra with cyclotron lines

    NASA Technical Reports Server (NTRS)

    Kargatis, Vincent; Liang, Edison P.

    1992-01-01

    Motivated by the recent developments in the cyclotron resonance upscattering of soft photons or CUSP model of Gamma Ray Burst (GBR) continuum spectra, we revisit a select database of GRBs with credible cyclotron absorption features. We measure the break energy of the continuum, the slope below the break and deduce the soft photon energy or the electron beam Lorentz factor cutoff. We study the correlation (or lack of) between various parameters in the context of the CUSP model. One surprise result is that there appears to be marginal correlation between the break energy and the spectral index below the break.

  9. VizieR Online Data Catalog: The cosmic TeV gamma-ray background spectrum (Inoue+, 2016)

    NASA Astrophysics Data System (ADS)

    Inoue, Y.; Tanaka, Y. T.

    2016-05-01

    We select 35 known extragalactic TeV sources which are located at Galactic latitude |b|>=10° and whose low activity state flux is available, since our aim is to give conservative constraints on the total cosmic gamma-ray background (CGB) in the TeV band. For each source, we select the lowest fluxes among several TeV measurements by modern imaging atmospheric Cherenkov telescopes (IACTs; H.E.S.S., MAGIC, and VERITAS) and further restrict samples showing no significant variability in the TeV band during observations. The sample contains 30 blazars, 3 radio galaxies, and 2 starburst galaxies from the default TeVcat catalog (Wakely & Horan 2008ICRC....3.1341W) which include published sources only. We also include the Fermi third source (3FGL) catalog data (Acero et al. 2015, J/ApJS/218/23) to cover GeV gamma-ray spectra. The 3FGL catalog is based on its first 48 months of survey data. All of our sample have counterparts in the 3FGL catalog. (2 data files).

  10. Lines and boxes: Unmasking Dynamical Dark Matter through correlations in the MeV gamma-ray spectrum

    NASA Astrophysics Data System (ADS)

    Boddy, Kimberly K.; Dienes, Keith R.; Kim, Doojin; Kumar, Jason; Park, Jong-Chul; Thomas, Brooks

    2016-11-01

    Identifying signatures of dark matter at indirect-detection experiments is generally more challenging for scenarios involving nonminimal dark sectors such as Dynamical Dark Matter (DDM) than for scenarios involving a single dark particle. This additional difficulty arises because the partitioning of the total dark-matter abundance across an ensemble of different constituent particles with different masses tends to "smear" the injection spectra of photons and other cosmic-ray particles that are produced via dark-matter annihilation or decay. As a result, the imprints of the dark sector on these cosmic-ray flux spectra typically take the form of continuum features rather than sharp peaks or lines. In this paper, however, we identify an unambiguous signature of nonminimal dark sectors such as DDM which can overcome these issues and potentially be observed at gamma-ray telescopes operating in the MeV range. We discuss the specific situations in which this signature can arise, and demonstrate that this signature can be exploited in order to significantly enhance our ability to resolve the unique spectral features of DDM and other nonminimal dark sectors at future gamma-ray facilities.

  11. The analysis of C 60 and C 70 fullerenes by prompt gamma neutron activation

    NASA Astrophysics Data System (ADS)

    Révay, Zs.; Belgya, T.; Molnár, G. L.; Rausch, H.; Braun, T.

    2006-06-01

    The capabilities of prompt gamma neutron activation analysis (PGAA) are examined for fullerene samples. As shown PGAA is a promising instrumental technique for the determination of the light elements of the periodic table. These elements (C, H, O, N and B) were inaccessible by instrumental neutron activation analysis (INAA) as done by the authors in previous publications.

  12. Data analysis of the COMPTEL instrument on the NASA gamma ray observatory

    NASA Technical Reports Server (NTRS)

    Diehl, R.; Bennett, K.; Collmar, W.; Connors, A.; Denherder, J. W.; Hermsen, W.; Lichti, G. G.; Lockwood, J. A.; Macri, J.; Mcconnell, M.

    1992-01-01

    The Compton imaging telescope (COMPTEL) on the Gamma Ray Observatory (GRO) is a wide field of view instrument. The coincidence measurement technique in two scintillation detector layers requires specific analysis methods. Straightforward event projection into the sky is impossible. Therefore, detector events are analyzed in a multi-dimensional dataspace using a gamma ray sky hypothesis convolved with the point spread function of the instrument in this dataspace. Background suppression and analysis techniques have important implications on the gamma ray source results for this background limited telescope. The COMPTEL collaboration applies a software system of analysis utilities, organized around a database management system. The use of this system for the assistance of guest investigators at the various collaboration sites and external sites is foreseen and allows different detail levels of cooperation with the COMPTEL institutes, dependent on the type of data to be studied.

  13. Spectrum image analysis tool - A flexible MATLAB solution to analyze EEL and CL spectrum images.

    PubMed

    Schmidt, Franz-Philipp; Hofer, Ferdinand; Krenn, Joachim R

    2017-02-01

    Spectrum imaging techniques, gaining simultaneously structural (image) and spectroscopic data, require appropriate and careful processing to extract information of the dataset. In this article we introduce a MATLAB based software that uses three dimensional data (EEL/CL spectrum image in dm3 format (Gatan Inc.'s DigitalMicrograph(®))) as input. A graphical user interface enables a fast and easy mapping of spectral dependent images and position dependent spectra. First, data processing such as background subtraction, deconvolution and denoising, second, multiple display options including an EEL/CL moviemaker and, third, the applicability on a large amount of data sets with a small work load makes this program an interesting tool to visualize otherwise hidden details. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Sparsity analysis of DS spread spectrum signals via theoretical analysis and dictionary learning

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Wu, Bin; Wang, Bo

    2017-04-01

    For the purpose of solving the problem of high sampling rate and massive data processing brought by high bandwidth in the field of Aerospace Communication, researchers applied CS theory to spread spectrum signal processing. Sparsity analysis is the prerequisite for the application of CS theory. This paper studies the sparsity of the DS spread spectrum signals, which is the most common kind of signal in the current TT&C systems. Based on the theoretical analysis we get the sparse dictionary, then the dictionary is optimized by K-SVD dictionary learning algorithm. The simulation results show that the two signals have strong sparsity in the constructed sparse base dictionary, which lays a theoretical foundation for the TT&C spread spectrum signal processing based on CS theory.

  15. Correlation Analysis of Prompt Emission from Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Pothapragada, Sriharsha

    Prompt emission from gamma-ray bursts (GRBs) exhibits very rapid, complicated temporal and spectral evolution. This diverse variability in the light-curves reflects the complicated nature of the underlying physics, in which inter-penetrating relativistic shells in the outflow are believed to generate strong magnetic fields that vary over very small scales. We use the theory of jitter radiation to model the emission from such regions and the resulting overall prompt gamma ray emission from a series of relativistic collisionless shocks. We present simulated GRB light-curves developed as a series of "pulses" corresponding to instantaneously illuminated "thin-shell" regions emitting via the jitter radiation mechanism. The effects of various geometries, viewing angles, and bulk Lorentz factor profiles of the radiating outflow jets on the spectral features and evolution of these light-curves are explored. Our results demonstrate how an anisotropic jitter radiation pattern, in conjunction with relativistic shock kinematics, can produce certain features observed in the GRB prompt emission spectra, such as the occurrence of hard, synchrotron violating spectra, the "tracking" of observed flux with spectral parameters, and spectral softening below peak energy within individual episodes of the light curve. We highlight predictions in the light of recent advances in the observational sphere of GRBs.

  16. Multivariate singular spectrum analysis and the road to phase synchronization

    NASA Astrophysics Data System (ADS)

    Groth, Andreas; Ghil, Michael

    2010-05-01

    Singular spectrum analysis (SSA) and multivariate SSA (M-SSA) are based on the classical work of Kosambi (1943), Loeve (1945) and Karhunen (1946) and are closely related to principal component analysis. They have been introduced into information theory by Bertero, Pike and co-workers (1982, 1984) and into dynamical systems analysis by Broomhead and King (1986a,b). Ghil, Vautard and associates have applied SSA and M-SSA to the temporal and spatio-temporal analysis of short and noisy time series in climate dynamics and other fields in the geosciences since the late 1980s. M-SSA provides insight into the unknown or partially known dynamics of the underlying system by decomposing the delay-coordinate phase space of a given multivariate time series into a set of data-adaptive orthonormal components. These components can be classified essentially into trends, oscillatory patterns and noise, and allow one to reconstruct a robust "skeleton" of the dynamical system's structure. For an overview we refer to Ghil et al. (Rev. Geophys., 2002). In this talk, we present M-SSA in the context of synchronization analysis and illustrate its ability to unveil information about the mechanisms behind the adjustment of rhythms in coupled dynamical systems. The focus of the talk is on the special case of phase synchronization between coupled chaotic oscillators (Rosenblum et al., PRL, 1996). Several ways of measuring phase synchronization are in use, and the robust definition of a reasonable phase for each oscillator is critical in each of them. We illustrate here the advantages of M-SSA in the automatic identification of oscillatory modes and in drawing conclusions about the transition to phase synchronization. Without using any a priori definition of a suitable phase, we show that M-SSA is able to detect phase synchronization in a chain of coupled chaotic oscillators (Osipov et al., PRE, 1996). Recently, Muller et al. (PRE, 2005) and Allefeld et al. (Intl. J. Bif. Chaos, 2007) have

  17. Analysis of Multi-band Photometry of Violently Variable Gamma-Ray Sources

    NASA Astrophysics Data System (ADS)

    Kadowaki, Jennifer; Malkan, M. A.

    2013-01-01

    We studied the relationship between rapid variations in the jet intensities and changes in accretion disk activity of blazar subtype, Flat Spectrum Radio Quasar (FSRQ). Fifteen known FSRQs were specifically chosen for their prominent big blue bumps with redshifts near z=1, in order for the rest-frame UV to be redshifted into the blue-band pass. Flux changes for these 15 FSRQs were monitored for 15 observational nights in BVRI-bands and 20 nights in JHK-bands over a 12 month period using NASA's Fermi Gamma-ray Space Telescope, Lick Observatory's Nickel Telescope, and Kitt Peak National Observatory's 2.1 m Telescope. With 6.3’ x 6.3’ field of view for Nickel’s Direct Imaging Camera and 20’ x 20’ for Flamingos IR Imaging Spectrometer, approximately a half dozen, bright and non-variable stars were available to compare the concurrent changes in each of the quasar’s brightness. This process of differential photometry yielded photometric measurements of quasar brightness with 1-2% level precision. Light curves were then created for these 15 monitored quasars in optical, infrared, and gamma-ray energy bands. Dominating the redder emission spectrum due to non-thermal, synchrotron radiation and compton scattering of gamma-rays off high energy electrons, jet activity was compared to bluer spectral regions having strong accretion disk component with rest frame of approximately 2000 Angstroms. Most of the targeted FSRQs varied significantly over the 12 month monitoring period, with varying levels of fluctuations for each observed wavelength. Some correlations between gamma-ray and optical wavelengths were also present, which will be further discussed in the poster.

  18. M-BAND Analysis of Chromosome Aberration In Human Epithelial Cells exposed to Gamma-ray and Secondary Neutrons of Low Dose Rate

    NASA Technical Reports Server (NTRS)

    Hada, M.; Saganti, P. B.; Gersey, B.; Wilkins, R.; Cucinotta, F. A.; Wu, H.

    2007-01-01

    High-energy secondary neutrons, produced by the interaction of galactic cosmic rays with the atmosphere, spacecraft structure and planetary surfaces, contribute to a significant fraction to the dose equivalent in crew members and passengers during commercial aviation travel, and astronauts in space missions. The Los Alamos Nuclear Science Center (LANSCE) neutron facility's "30L" beam line is known to generate neutrons that simulate the secondary neutron spectrum of the Earth's atmosphere at high altitude. The neutron spectrum is also similar to that measured onboard spacecraft like the MIR and the International Space Station (ISS). To evaluate the biological damage, we exposed human epithelial cells in vitro to the LANSCE neutron beams at an entrance dose rate of 2.5 cGy/hr or gamma-ray at 1.7cGy/hr, and assessed the induction of chromosome aberrations that were identified with mBAND. With this technique, individually painted chromosomal bands on one chromosome allowed the identification of inter-chromosomal aberrations (translocation to unpainted chromosomes) and intra-chromosomal aberrations (inversions and deletions within a single painted chromosome). Compared to our previous results for gamma-rays and 600 MeV/nucleon Fe ions of high dose rate, the neutron data showed a higher frequency of chromosome aberrations. However, detailed analysis of the inversion type revealed that all of the three radiation types in the study induced a low incidence of simple inversions. The low dose rate gamma-rays induced a lower frequency of chromosome aberrations than high dose rate gamma-rays, but the inversion spectrum was similar for the same cytotoxic effect. The distribution of damage sites on chromosome 3 for different radiation types will also be discussed.

  19. M-BAND Analysis of Chromosome Aberration In Human Epithelial Cells exposed to Gamma-ray and Secondary Neutrons of Low Dose Rate

    NASA Technical Reports Server (NTRS)

    Hada, M.; Saganti, P. B.; Gersey, B.; Wilkins, R.; Cucinotta, F. A.; Wu, H.

    2007-01-01

    High-energy secondary neutrons, produced by the interaction of galactic cosmic rays with the atmosphere, spacecraft structure and planetary surfaces, contribute to a significant fraction to the dose equivalent in crew members and passengers during commercial aviation travel, and astronauts in space missions. The Los Alamos Nuclear Science Center (LANSCE) neutron facility's "30L" beam line is known to generate neutrons that simulate the secondary neutron spectrum of the Earth's atmosphere at high altitude. The neutron spectrum is also similar to that measured onboard spacecraft like the MIR and the International Space Station (ISS). To evaluate the biological damage, we exposed human epithelial cells in vitro to the LANSCE neutron beams at an entrance dose rate of 2.5 cGy/hr or gamma-ray at 1.7cGy/hr, and assessed the induction of chromosome aberrations that were identified with mBAND. With this technique, individually painted chromosomal bands on one chromosome allowed the identification of inter-chromosomal aberrations (translocation to unpainted chromosomes) and intra-chromosomal aberrations (inversions and deletions within a single painted chromosome). Compared to our previous results for gamma-rays and 600 MeV/nucleon Fe ions of high dose rate, the neutron data showed a higher frequency of chromosome aberrations. However, detailed analysis of the inversion type revealed that all of the three radiation types in the study induced a low incidence of simple inversions. The low dose rate gamma-rays induced a lower frequency of chromosome aberrations than high dose rate gamma-rays, but the inversion spectrum was similar for the same cytotoxic effect. The distribution of damage sites on chromosome 3 for different radiation types will also be discussed.

  20. Measurement of the Shape of the Optical-IR Spectrum of Prompt Emission from Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Grossan, Bruce; Kistubayev, 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

  1. A low, adaptive dose of gamma-rays reduced the number and altered the spectrum of S1- mutants in human-hamster hybrid AL cells

    NASA Technical Reports Server (NTRS)

    Ueno, A. M.; Vannais, D. B.; Gustafson, D. L.; Wong, J. C.; Waldren, C. A.

    1996-01-01

    We examined the effects of a low, adaptive dose of 137Cs-gamma-irradiation (0.04 Gy) on the number and kinds of mutants induced in AL human-hamster hybrid cells by a later challenge dose of 4 Gy. The yield of S1- mutants was significantly less (by 53%) after exposure to both the adaptive and challenge doses compared to the challenge dose alone. The yield of hprt- mutants was similarly decreased. Incubation with cycloheximide (CX) or 3-aminobenzamide largely negated the decrease in mutant yield. The adaptive dose did not perturb the cell cycle, was not cytotoxic, and did not of itself increase the mutant yield above background. The adaptive dose did, however, alter the spectrum of S1- mutants from populations exposed only to the adaptive dose, as well as affecting the spectrum of S1- mutants generated by the challenge dose. The major change in both cases was a significant increase in the proportion of complex mutations compared to small mutations and simple deletions.

  2. A low, adaptive dose of gamma-rays reduced the number and altered the spectrum of S1- mutants in human-hamster hybrid AL cells

    NASA Technical Reports Server (NTRS)

    Ueno, A. M.; Vannais, D. B.; Gustafson, D. L.; Wong, J. C.; Waldren, C. A.

    1996-01-01

    We examined the effects of a low, adaptive dose of 137Cs-gamma-irradiation (0.04 Gy) on the number and kinds of mutants induced in AL human-hamster hybrid cells by a later challenge dose of 4 Gy. The yield of S1- mutants was significantly less (by 53%) after exposure to both the adaptive and challenge doses compared to the challenge dose alone. The yield of hprt- mutants was similarly decreased. Incubation with cycloheximide (CX) or 3-aminobenzamide largely negated the decrease in mutant yield. The adaptive dose did not perturb the cell cycle, was not cytotoxic, and did not of itself increase the mutant yield above background. The adaptive dose did, however, alter the spectrum of S1- mutants from populations exposed only to the adaptive dose, as well as affecting the spectrum of S1- mutants generated by the challenge dose. The major change in both cases was a significant increase in the proportion of complex mutations compared to small mutations and simple deletions.

  3. Whether the Autism Spectrum Quotient consists of two different subgroups? Cluster analysis of the Autism Spectrum Quotient in general population.

    PubMed

    Kitazoe, Noriko; Fujita, Naofumi; Izumoto, Yuji; Terada, Shin-Ichi; Hatakenaka, Yuhei

    2017-04-01

    The purpose of this study was to investigate whether the individuals in the general population with high scores on the Autism Spectrum Quotient constituted a single homogeneous group or not. A cohort of university students (n = 4901) was investigated by cluster analysis based on the original five subscales of the Autism Spectrum Quotient. Based on the results of the analysis, the students could be divided into six clusters: the first with low scores on all the five subscales, the second with high scores on only the 'attention to detail' subscale, the third and fourth with intermediate scores on all the subscales, the fifth with high scores on four of the five subscales but low scores on the 'attention to detail' subscale and the sixth with high scores on all the five subscales. The students with high total Autism Spectrum Quotient scores (n = 166) were divided into two groups: one with high scores on four subscales but low scores on the 'attention to detail' subscale and the other with high scores on all the five subscales. The results of this study suggested that individuals from the general population with high Autism Spectrum Quotient scores may consist of two qualitatively different groups.

  4. Multiple spectrum analysis and evaluation for optical constants of HfO2 thin films

    NASA Astrophysics Data System (ADS)

    Liu, Dandan; Liu, Huasong; Jiang, Chenghui; Jiang, Yugang; Wang, Lishuan; Zhao, Zhihong; Ji, Yiqin

    2014-08-01

    HfO2 thin films were deposited on ZS1 silica by Ion Beam Sputtering (IBS) technique. Optical constants of HfO2 thin films were obtained by multiple spectrum analysis method, which combined the transmittance spectrum and ellipsometry spectrum of the film. The refractive index and extinction coiefficient of HfO2 thin films were evaluated by etching experiments of the film. The analysis spectral range was between 250nm and 850nm.

  5. Roller element bearing fault diagnosis using singular spectrum analysis

    NASA Astrophysics Data System (ADS)

    Muruganatham, Bubathi; Sanjith, M. A.; Krishnakumar, B.; Satya Murty, S. A. V.

    2013-02-01

    Most of the existing time series methods of feature extraction involve complex algorithm and the extracted features are affected by sample size and noise. In this paper, a simple time series method for bearing fault feature extraction using singular spectrum analysis (SSA) of the vibration signal is proposed. The method is easy to implement and fault feature is noise immune. SSA is used for the decomposition of the acquired signals into an additive set of principal components. A new approach for the selection of the principal components is also presented. Two methods of feature extraction based on SSA are implemented. In first method, the singular values (SV) of the selected SV number are adopted as the fault features, and in second method, the energy of the principal components corresponding to the selected SV numbers are used as features. An artificial neural network (ANN) is used for fault diagnosis. The algorithms were evaluated using two experimental datasets—one from a motor bearing subjected to different fault severity levels at various loads, with and without noise, and the other with bearing vibration data obtained in the presence of a gearbox. The effect of sample size, fault size and load on the fault feature is studied. The advantages of the proposed method over the exiting time series method are discussed. The experimental results demonstrate that the proposed bearing fault diagnosis method is simple, noise tolerant and efficient.

  6. The Spectrum and Term Analysis of V II

    NASA Astrophysics Data System (ADS)

    Thorne, A. P.; Pickering, J. C.; Semeniuk, J. I.

    2013-07-01

    The spectrum and extended term analysis of V II are presented. Fourier transform spectrometry was used to record high resolution spectra of singly ionized vanadium in the region 1492-5800 Å (67020-17260 cm-1) with vanadium-neon and vanadium-argon hollow cathode lamps as sources. The wavenumber uncertainty for the center of gravity of the strongest lines is typically 0.002 cm-1, an improvement of an order of magnitude over previous measurements. Most of the lines exhibit partly resolved hyperfine structure. The V II energy levels in the 1985 compilation of Sugar and Corliss have been confirmed and revised, with the exception of the high-lying 4f levels and eight of the lower levels. Thirty-nine of the additional eighty-five high levels published by Iglesias et al. have also been confirmed and revised, and three of their missing levels have been found. The energy uncertainty of the revised levels has been reduced by about an order of magnitude. In total, 176 even levels and 233 odd levels are presented. Wavenumbers and classifications are given for 1242 V II lines.

  7. THE SPECTRUM AND TERM ANALYSIS OF V II

    SciTech Connect

    Thorne, A. P.; Pickering, J. C.; Semeniuk, J. I.

    2013-07-15

    The spectrum and extended term analysis of V II are presented. Fourier transform spectrometry was used to record high resolution spectra of singly ionized vanadium in the region 1492-5800 A (67020-17260 cm{sup -1}) with vanadium-neon and vanadium-argon hollow cathode lamps as sources. The wavenumber uncertainty for the center of gravity of the strongest lines is typically 0.002 cm{sup -1}, an improvement of an order of magnitude over previous measurements. Most of the lines exhibit partly resolved hyperfine structure. The V II energy levels in the 1985 compilation of Sugar and Corliss have been confirmed and revised, with the exception of the high-lying 4f levels and eight of the lower levels. Thirty-nine of the additional eighty-five high levels published by Iglesias et al. have also been confirmed and revised, and three of their missing levels have been found. The energy uncertainty of the revised levels has been reduced by about an order of magnitude. In total, 176 even levels and 233 odd levels are presented. Wavenumbers and classifications are given for 1242 V II lines.

  8. Study of medical isotope production facility stack emissions and noble gas isotopic signature using automatic gamma-spectra analysis platform

    NASA Astrophysics Data System (ADS)

    Zhang, Weihua; Hoffmann, Emmy; Ungar, Kurt; Dolinar, George; Miley, Harry; Mekarski, Pawel; Schrom, Brian; Hoffman, Ian; Lawrie, Ryan; Loosz, Tom

    2013-04-01

    The nuclear industry emissions of the four CTBT (Comprehensive Nuclear-Test-Ban Treaty) relevant radioxenon isotopes are unavoidably detected by the IMS along with possible treaty violations. Another civil source of radioxenon emissions which contributes to the global background is radiopharmaceutical production companies. To better understand the source terms of these background emissions, a joint project between HC, ANSTO, PNNL and CRL was formed to install real-time detection systems to support 135Xe, 133Xe, 131mXe and 133mXe measurements at the ANSTO and CRL 99Mo production facility stacks as well as the CANDU (CANada Deuterium Uranium) primary coolant monitoring system at CRL. At each site, high resolution gamma spectra were collected every 15 minutes using a HPGe detector to continuously monitor a bypass feed from the stack or CANDU primary coolant system as it passed through a sampling cell. HC also conducted atmospheric monitoring for radioxenon at approximately 200 km distant from CRL. A program was written to transfer each spectrum into a text file format suitable for the automatic gamma-spectra analysis platform and then email the file to a server. Once the email was received by the server, it was automatically analysed with the gamma-spectrum software UniSampo/Shaman to perform radionuclide identification and activity calculation for a large number of gamma-spectra in a short period of time (less than 10 seconds per spectrum). The results of nuclide activity together with other spectrum parameters were saved into the Linssi database. This database contains a large amount of radionuclide information which is a valuable resource for the analysis of radionuclide distribution within the noble gas fission product emissions. The results could be useful to identify the specific mechanisms of the activity release. The isotopic signatures of the various radioxenon species can be determined as a function of release time. Comparison of 133mXe and 133Xe activity

  9. Mapping Upper Mantle Seismic Discontinuities Using Singular Spectrum Analysis

    NASA Astrophysics Data System (ADS)

    Gu, Y. J.; Dokht, R.; Sacchi, M. D.

    2015-12-01

    Seismic discontinuities are fundamental to the understanding of mantle composition and dynamics. Their depth and impedance are generally determined using secondary seismic phases, most commonly SS precursors and P-to-S converted waves. However, the analysis and interpretation using these approaches often suffer from incomplete data coverage, high noise levels and interfering seismic phases, especially near tectonically complex regions such as subduction zones and continental margins. To overcome these pitfalls, we apply Singular Spectrum Analysis (SSA) to remove random noise, reconstruct missing traces and enhance the robustness of SS precursors and P-to-S conversions from seismic discontinuities. Our method takes advantage of the predictability of time series in frequency-space domain and performs a rank reduction using a singular value decomposition of the trajectory matrix. We apply SSA to synthetic record sections as well as observations of 1) SS precursors beneath the northwestern Pacific subduction zones, and 2) P-to-S converted waves from the Western Canada Sedimentary Basin (WCSB). In comparison with raw or interpolated data, the SSA enhanced reflectivity maps show a greater resolution and a stronger negative correlation between the depths of the 410 and 660 km discontinuities. These effects can be attributed to the suppression of incoherent noise, which tends to reduce the signal amplitude during normal averaging procedures, through rank reduction and the emphasis of principle singular values. Our new results suggest a more laterally coherent 520 km reflection in the western Pacific regions. Similar improvements in data imaging are achieved in western Canada, where strong lateral variations in discontinuity topography are observed in the craton-Cordillera boundary zone. Improvements from SSA relative to conventional approaches are most notable in under-sampled regions.

  10. An analysis of gamma ray burst time histories

    NASA Technical Reports Server (NTRS)

    Lestrade, John Patrick; Karr, Gerald R.

    1994-01-01

    Gamma ray burst time histories, ranging in durations from milliseconds to thousands of seconds, are as varied as the number of bursts. They show a wide array of structures from those that are very smooth to those that contain a seemingly uncountable number of spikes riding on top of other spikes. These profiles have tantalized researchers for years - they obviously hold important information on the nature of GRB's, but to date no one has been successful in analyzing them. For the past year the author has been working on algorithms to analyze these data. Two approaches have been followed in this investigation. The first is an attempt to quantify the amount of structure, or spikiness, in a profile. The second involves applying the latest theorems on chaos and fractals with the aim of extracting useful information from what seems to be a random collection of shot noise.

  11. Analysis of the p p-bar mass spectrum in J/Psi

    SciTech Connect

    J. Haidenbauer; S. Krewald; U.-G. Meissner; A. Sibirtsev; A. W. Thomas

    2005-05-16

    The near-threshold enhancement in the p p-bar invariant mass spectrum of the reaction J/Psi --> gamma p p-bar, observed in an experiment by the BES Collaboration, is analysed. It is shown, within the Watson-Migdal approach to final state interactions, that the mass dependence of the p p-bar spectrum close to the threshold can be reproduced by the S-wave p p-bar interaction of the Jülich N N-bar model in the isospin I=1 state. Difficulties in the consistent interpretation of the p invariant mass spectrum of the reaction J/Psi --> pi^0 p p-bar, where there are no obvious signs for a final state interaction, are discussed.

  12. A bulk analysis system using the prompt gamma neutron activation method and neural network

    NASA Astrophysics Data System (ADS)

    Taheri, Ali; Heidary, Saeed; Gholipour Peyvandi, Reza

    2017-06-01

    In this work, an on-line and bulk analysis system based on the prompt gamma neutron activation method and neural network is introduced. Using a setup that includes a 252Cf source and a BGO scintillator detector, a set of semi-experimental data obtained from cement raw materials is produced to train an optimized neural network. The neural network is trained based on a back-propagation algorithm with 100 experimental prompt gamma-ray spectra. The elements existing in the different cement samples are specified. With a good precision compared to the least square analysis, the ANN (Artificial Neural Network) could identify elements. One of the key points in this work is that more than 100 different prompt gamma spectra of neutron activated samples were produced without the need for different cement samples or Monte Carlo simulations.

  13. Monte-carlo simulation of the prompt gamma neutron activation analysis system with a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Shim, Hyunha; Hong, Byungsik; Lee, Kyong-Sei; Lee, Sungman; Cha, Hyungki

    2012-09-01

    The prompt gamma neutron activation analysis (PGNAA) system is a useful tool to detect the concentrations of the various composite elements of a sample by measuring the prompt gammas that are activated by neutrons. The composition in terms of the constituent elements is essential information for the identification of the material species of any unknown object. A PGNAA system initiated by a high-power laser has been designed and optimized by using a Monte-Carlo simulation. In order to improve the signal-to-background ratio, we designed an improved neutron-shielding structure and imposed a proper time window in the analysis. In particular, the yield ratio of nitrogen to carbon in a TNT sample was investigated in detail. These simulation results demonstrate that the gamma rays from an explosive sample under a vast level of background can indeed be identified.

  14. Feasibility study of plutonium isotopic analysis of resin beads by nondestructive gamma-ray spectroscopy

    SciTech Connect

    Li, T.K.

    1985-01-01

    We have initiated a feasibility study on the use of nondestructive low-energy gamma-ray spectroscopy for plutonium isotopic analysis on resin beads. Seven resin bead samples were measured, with each sample containing an average of 9 ..mu..g of plutonium; the isotopic compositions of the samples varied over a wide range. The gamma-ray spectroscopy results, obtained from 4-h counting-time measurements, were compared with mass spectrometry results. The average ratios of gamma-ray spectroscopy to mass spectrometry were 1.014 +- 0.025 for /sup 238/Pu//sup 239/Pu, 0.996 +- 0.018 for /sup 240/Pu//sup 239/Pu, and 0.980 +- 0.038 for /sup 241/Pu//sup 239/Pu. The rapid, automated, and accurate nondestructive isotopic analysis of resin beads may be very useful to process technicians and International Atomic Energy Agency inspectors. 3 refs., 1 fig., 3 tabs.

  15. A compact neutron beam generator system designed for prompt gamma nuclear activation analysis.

    PubMed

    Ghassoun, J; Mostacci, D

    2011-08-01

    In this work a compact system was designed for bulk sample analysis using the technique of PGNAA. The system consists of (252)Cf fission neutron source, a moderator/reflector/filter assembly, and a suitable enclosure to delimit the resulting neutron beam. The moderator/reflector/filter arrangement has been optimised to maximise the thermal neutron component useful for samples analysis with a suitably low level of beam contamination. The neutron beam delivered by this compact system is used to irradiate the sample and the prompt gamma rays produced by neutron reactions within the sample elements are detected by appropriate gamma rays detector. Neutron and gamma rays transport calculations have been performed using the Monte Carlo N-Particle transport code (MCNP5).

  16. Isotopic composition analysis and age dating of uranium samples by high resolution gamma ray spectrometry

    NASA Astrophysics Data System (ADS)

    Apostol, A. I.; Pantelica, A.; Sima, O.; Fugaru, V.

    2016-09-01

    Non-destructive methods were applied to determine the isotopic composition and the time elapsed since last chemical purification of nine uranium samples. The applied methods are based on measuring gamma and X radiations of uranium samples by high resolution low energy gamma spectrometric system with planar high purity germanium detector and low background gamma spectrometric system with coaxial high purity germanium detector. The ;Multigroup γ-ray Analysis Method for Uranium; (MGAU) code was used for the precise determination of samples' isotopic composition. The age of the samples was determined from the isotopic ratio 214Bi/234U. This ratio was calculated from the analyzed spectra of each uranium sample, using relative detection efficiency. Special attention is paid to the coincidence summing corrections that have to be taken into account when performing this type of analysis. In addition, an alternative approach for the age determination using full energy peak efficiencies obtained by Monte Carlo simulations with the GESPECOR code is described.

  17. Development of a correction method for the time-of-flight prompt gamma-ray analysis

    NASA Astrophysics Data System (ADS)

    Huang, M.; Toh, Y.; Ebihara, M.; Kimura, A.; Nakamura, S.

    2017-03-01

    A new analytical technique, time-of-flight prompt gamma-ray analysis, has been developed at the Japan Proton Accelerator Research Complex. In order to apply it to accurate elemental analysis, a set of Fe and Au reference samples were measured to examine the several factors which affect the number of detected events. It was found that major contributing factors included attenuations of neutrons and gamma rays in the sample, live-time fraction and signal pile-up correction. A simulation model was built for the estimation of neutron and gamma-ray attenuations. A simple empirical formula was proposed to calculate the signal pile-up correction factor. The whole correction method has proven to be accurate and reliable.

  18. Monte Carlo simulations of plutonium gamma-ray spectra

    SciTech Connect

    Koenig, Z.M.; Carlson, J.B.; Wang, Tzu-Fang; Ruhter, W.D.

    1993-07-16

    Monte Carlo calculations were investigated as a means of simulating the gamma-ray spectra of Pu. These simulated spectra will be used to develop and evaluate gamma-ray analysis techniques for various nondestructive measurements. Simulated spectra of calculational standards can be used for code intercomparisons, to understand systematic biases and to estimate minimum detection levels of existing and proposed nondestructive analysis instruments. The capability to simulate gamma-ray spectra from HPGe detectors could significantly reduce the costs of preparing large numbers of real reference materials. MCNP was used for the Monte Carlo transport of the photons. Results from the MCNP calculations were folded in with a detector response function for a realistic spectrum. Plutonium spectrum peaks were produced with Lorentzian shapes, for the x-rays, and Gaussian distributions. The MGA code determined the Pu isotopes and specific power of this calculated spectrum and compared it to a similar analysis on a measured spectrum.

  19. [A Composition Analysis Method of Mixed Pigments Based on Spectrum Expression and Independent Component Analysis].

    PubMed

    Wang, Gong-ming; Liu, Zhi-yong

    2015-06-01

    Reflectance spectrometry is a common method in composition analysis of mixed pigments. In this method, similarity is used to determine the type of basic pigments that constitute the mixed pigments. But its result may be inaccurate because it is easily influenced by a variety of basic pigments. In this study, a composition analysis method of mixed pigments based on spectrum expression and independent component analysis is proposed, and the composition of mixed pigments can be calculated accurately. First of all, the spectral information of mixed pigments is obtained with spectrometer, and is expressed as the discrete signal. After that, the spectral information of basic pigments is deduced with independent component analysis. Then, the types of basic pigments are determined by calculating the spectrum similarity between the basic pigments and known pigments. Finally, the ratios of basic pigments are obtained by solving the Kubelka-Munk equation system. In addition, the simulated spectrum data of Munsell color card is used to validate this method. The compositions of mixed pigments from three basic pigments are determined under the circumstance of normality and disturbance. And the compositions of mixture from several pigments within the set of eight basic pigments are deduced successfully. The curves of separated pigment spectrums are very similar to the curves of original pigment spectrums. The average similarity is 97.72%, and the maximum one can reach to 99.95%. The calculated ratios of basic pigments close to the original one. It can be seen that this method is suitable for composition analysis of mixed pigments.

  20. Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived from First-Year Fermi Large Area Telescope Data

    DOE PAGES

    Abdo, A. A.

    2010-03-08

    Here, we report on the first Fermi Large Area Telescope (LAT) measurements of the so-called “extragalactic” diffuse γ -ray emission (EGB). This component of the diffuse γ -ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modeling of the bright foreground diffuse Galactic γ -ray emission, the detected LAT sources, and the solar γ -ray emission. We also find the spectrum of the EGB is consistent with a power law with a differential spectral index γ =more » 2.41 ± 0.05 and intensity I ( > 100 MeV ) = ( 1.03 ± 0.17 ) × 10 - 5 cm -2 s - 1 sr - 1 , where the error is systematics dominated. The EGB spectrum, presented here, is featureless, less intense, and softer than that derived from EGRET data.« less

  1. Spectrum analysis techniques for personnel detection using seismic sensors

    NASA Astrophysics Data System (ADS)

    Houston, Kenneth M.; McGaffigan, Daniel P.

    2003-09-01

    There is a general need for improved detection range and false alarm performance for seismic sensors used for personnel detection. In this paper we describe a novel footstep detection algorithm which was developed and run on seismic footstep data collected at the Aberdeen Proving Ground in December 2000. The initial focus was an assessment of achievable detection range. The conventional approach to footstep detection is to detect transients corresponding to individual footfalls. We feel this is an error-prone approach. Because many real-world signals unrelated to human locomotion look like transients, transient-based footstep detection will inevitably either suffer from high false alarm rates or will be insensitive. Instead, we examined the use of spectrum analysis on envelope-detected seismic signals and have found the general method to be quite promising, not only for detection, but also for discrimination against other types of seismic sources. In particular, gait patterns and their corresponding signatures may help discriminate between human intruders and animals. In the APG data set, mean detection ranges of 64 meters (at PD=50%) were observed for normal walking, significantly improving on ranges previously reported. For running, mean detection ranges of 84 meters were observed. However, stealthy walking (creeping) remains a considerable problem. Even at short ranges (10 meters), in some cases the detection rate was less than 50%. In future efforts, additional data sets for a range of geologic and environmental conditions should be acquired and analyzed. Improvements to the detection algorithms are possible, including estimation of direction of travel and the number of intruders.

  2. Functional connectivity between brain areas estimated by analysis of gamma waves.

    PubMed

    Kheiri, Farshad; Bragin, Anatol; Engel, Jerome

    2013-04-15

    The goal of this study is to investigate functional connectivity between different brain regions by analyzing the temporal relationship of the maxima of gamma waves recorded in multiple brain areas. Local field potentials were recorded from motor cortex, hippocampus, entorhinal cortex and piriform cortex of rats. Gamma activity was filtered and separated into two bands; high (65-90Hz) and low (30-55Hz) gamma. Maxima for gamma activity waves were detected and functional connectivity between different brain regions was determined using Shannon entropy for perievent histograms for each pair channels. Significant Shannon entropy values were reported as connectivity factors. We defined a connectivity matrix based the connectivity factors between different regions. We found that maxima of low and high frequency gamma occur in strong temporal relationship between some brain areas, indicating the existence of functional connections between these areas. The spatial pattern of functional connections between brain areas was different for slow wave sleep and waking states. However for each behavioral state in the same animal the pattern of functional connections was stable over time within 30min of continuous analysis and over a 5 day period. With the same electrode montage the pattern of functional connectivity varied from one subject to another. Analysis of the temporal relationship of maxima of gamma waves between various brain areas could be a useful tool for investigation of functional connections between these brain areas. This approach could be applied for analysis of functional alterations occurring in these connections during different behavioral tasks and during processes related to learning and memory. The specificity in the connectivity pattern from one subject to another can be explained by the existence of unique functional networks for each subject. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. HESS J1427-608: An Unusual Hard, Unbroken Gamma-Ray Spectrum in a Very Wide Energy Range

    NASA Astrophysics Data System (ADS)

    Guo, Xiao-Lei; Xin, Yu-Liang; Liao, Neng-Hui; Yuan, Qiang; Gao, Wei-Hong; He, Hao-Ning; Fan, Yi-Zhong; Liu, Si-Ming

    2017-01-01

    We report the detection of a GeV γ-ray source that spatially overlaps and is thus very likely associated with the unidentified very high energy (VHE) γ-ray source HESS J1427‑608 with the Pass 8 data recorded by the Fermi Large Area Telescope. The photon spectrum of this source is best described by a power law with an index of 1.85 ± 0.17 in the energy range of 3–500 GeV, and the measured flux connects smoothly with that of HESS J1427‑608 at a few hundred gigaelectronvolts. This source shows no significant extension and time variation. The broadband GeV to TeV emission over four decades of energies can be well fitted by a single power-law function with an index of 2.0, without obvious indication of spectral cutoff toward high energies. Such a result implies that HESS J1427‑608 may be a PeV particle accelerator. We discuss the possible nature of HESS J1427‑608 according to the multiwavelength spectral fittings. Given the relatively large errors, either a leptonic or a hadronic model can explain the multiwavelength data from radio to VHE γ-rays. The inferred magnetic field strength is a few micro-Gauss, which is smaller than the typical values of supernova remnants (SNRs) and is consistent with some pulsar wind nebulae (PWNe). On the other hand, the flat γ-ray spectrum is slightly different from typical PWNe but is similar to that of some known SNRs.

  4. 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...

  5. Dosimetric comparison of tools for intensity modulated radiation therapy with gamma analysis: a phantom study

    NASA Astrophysics Data System (ADS)

    Akbas, Ugur; Okutan, Murat; Demir, Bayram; Koksal, Canan

    2015-07-01

    Dosimetry of the Intensity Modulated Radiation Therapy (IMRT) is very important because of the complex dose distributions. Diode arrays are the most common and practical measurement tools for clinical usage for IMRT. Phantom selection is critical for QA process. IMRT treatment plans are recalculated for the phantom irradiation in QA. Phantoms are made in different geometrical shapes to measure the doses of different types of irradiation techniques. Comparison of measured and calculated dose distributions for IMRT can be made by using gamma analysis. In this study, 10 head-and-neck IMRT QA plans were created with Varian Eclipse 8.9 treatment planning system. Water equivalent RW3-slab phantoms, Octavius-2 phantom and PTW Seven29 2D-array were used for QA measurements. Gantry, collimator and couch positions set to 00 and QA plans were delivered to RW3 and Octavius phantoms. Then the positions set to original angles and QA plans irradiated again. Measured and calculated fluence maps were evaluated with gamma analysis for different DD and DTA criteria. The effect of different set-up conditions for RW3 and Octavius phantoms in QA plan delivery evaluated by gamma analysis. Results of gamma analysis show that using RW3-slab phantoms with setting parameters to 00 is more appropriate for IMRT QA.

  6. Imaging of heterogeneous materials by prompt gamma-ray neutron activation analysis

    SciTech Connect

    Staples, P.; Prettyman, T.; Lestone, J.

    1998-12-01

    The authors have used a tomographic gamma scanner (TGS) to produce tomographic prompt gamma-ray neutron activation analysis imaging (PGNAA) of heterogeneous matrices. The TGS was modified by the addition of graphite reflectors that contain isotopic neutron sources for sample interrogation. The authors are in the process of developing the analysis methodology necessary for a quantitative assay of large containers of heterogeneous material. This nondestructive analysis (NDA) technique can be used for material characterization and the determination of neutron assay correction factors. The most difficult question to be answered is the determination of the source-to-sample coupling term. To assist in the determination of the coupling term, the authors have obtained images for a range of sample that are very well characterized, such as, homogenous pseudo one-dimensional samples to three-dimensional heterogeneous samples. They then compare the measurements to MCNP calculations. For an accurate quantitative measurement, it is also necessary to determine the sample gamma-ray self attenuation at higher gamma-ray energies, namely pair production should be incorporated into the analysis codes.

  7. GC-MS Analysis of [gamma]-Hydroxybutyric Acid Analogs: A Forensic Chemistry Experiment

    ERIC Educational Resources Information Center

    Henck, Colin; Nally, Luke

    2007-01-01

    An upper-division forensic chemistry experiment is described. It involves using glycolic acid and sodium glycolate as analogs of [gamma]-hydroxybutyric acid and its sodium salt. The experiment shows the use of silylation in GC-MS analysis and gives students the opportunity to work with a commonly used silylating reagent,…

  8. Documentation of the data analysis system for the gamma ray monitor aboard OSO-H

    NASA Technical Reports Server (NTRS)

    Croteau, S.; Buck, A.; Higbie, P.; Kantauskis, J.; Foss, S.; Chupp, D.; Forrest, D. J.; Suri, A.; Gleske, I.

    1973-01-01

    The programming system is presented which was developed to prepare the data from the gamma ray monitor on OSO-7 for scientific analysis. The detector, data, and objectives are described in detail. Programs presented include; FEEDER, PASS-1, CAL1, CAL2, PASS-3, Van Allen Belt Predict Program, Computation Center Plot Routine, and Response Function Programs.

  9. GC-MS Analysis of [gamma]-Hydroxybutyric Acid Analogs: A Forensic Chemistry Experiment

    ERIC Educational Resources Information Center

    Henck, Colin; Nally, Luke

    2007-01-01

    An upper-division forensic chemistry experiment is described. It involves using glycolic acid and sodium glycolate as analogs of [gamma]-hydroxybutyric acid and its sodium salt. The experiment shows the use of silylation in GC-MS analysis and gives students the opportunity to work with a commonly used silylating reagent,…

  10. Gamma Detector Response and Analysis Software%u2013Detector Response Function

    SciTech Connect

    2015-04-01

    Version 00 GADRAS-DRF contains a suite of capabilities related to radiation detection. Its primary function is the simulation of gamma-ray and neutron detector signals to radiation sources. It also contains limited analysis functionality. GADRAS-DRF is the public version of the full version of GADRAS with capabilities such as radiation transport and advanced analyses removed.

  11. High Resolution Gamma Ray Analysis of Medical Isotopes

    NASA Astrophysics Data System (ADS)

    Chillery, Thomas

    2015-10-01

    Compton-suppressed high-purity Germanium detectors at the University of Massachusetts Lowell have been used to study medical radioisotopes produced at Brookhaven Linac Isotope Producer (BLIP), in particular isotopes such as Pt-191 used for cancer therapy in patients. The ability to precisely analyze the concentrations of such radio-isotopes is essential for both production facilities such as Brookhaven and consumer hospitals across the U.S. Without accurate knowledge of the quantities and strengths of these isotopes, it is possible for doctors to administer incorrect dosages to patients, thus leading to undesired results. Samples have been produced at Brookhaven and shipped to UML, and the advanced electronics and data acquisition capabilities at UML have been used to extract peak areas in the gamma decay spectra. Levels of Pt isotopes in diluted samples have been quantified, and reaction cross-sections deduced from the irradiation parameters. These provide both cross checks with published work, as well as a rigorous quantitative framework with high quality state-of-the-art detection apparatus in use in the experimental nuclear physics community.

  12. An Analysis Methodology for the Gamma-ray Large Area Space Telescope

    NASA Technical Reports Server (NTRS)

    Morris, Robin D.; Cohen-Tanugi, Johann

    2004-01-01

    The Large Area Telescope (LAT) instrument on the Gamma Ray Large Area Space Telescope (GLAST) has been designed to detect high-energy gamma rays and determine their direction of incidence and energy. We propose a reconstruction algorithm based on recent advances in statistical methodology. This method, alternative to the standard event analysis inherited from high energy collider physics experiments, incorporates more accurately the physical processes occurring in the detector, and makes full use of the statistical information available. It could thus provide a better estimate of the direction and energy of the primary photon.

  13. Detection and depth profiling of hazardous elements using N-SCAN prompt gamma neutron activation analysis

    SciTech Connect

    Ruddy, F.H.; Congedo, T.V.; Dulloo, A.R.

    1995-12-31

    A low-background method of prompt gamma neutron activation analysis (PGNAA) has been developed and demonstrated. This method employs a pulsed electronic neutron generator, a high resolution, high purity germanium detector, and microsecond coordination of neutron pulsing and gamma detection through a computer-controlled acquisition interface module. The system has been used to detect trace amounts of hazardous elements in concretes and soils to provide depth profiles of contaminant burden down to nearly 1 ft in packed soil, and also to perform rapid identification of the contents of munitions bearing simulants of chemical weapons agents.

  14. [Chlorophyll fluorescence spectrum analysis of greenhouse cucumber disease and insect damage].

    PubMed

    Sui, Yuan-yuan; Yu, Hai-ye; Zhang, Lei; Luo, Han; Ren, Shun; Zhao, Guo-gang

    2012-05-01

    The present paper is based on chlorophyll fluorescence spectrum analysis. The wavelength 685 nm was determined as the primary characteristic point for the analysis of healthy or disease and insect damaged leaf by spectrum configuration. Dimensionality reduction of the spectrum was achieved by combining simple intercorrelation bands selection and principal component analysis (PCA). The principal component factor was reduced from 10 to 5 while the spectrum information was kept reaching 99.999%. By comparing and analysing three modeling methods, namely the partial least square regression (PLSR), BP neural network (BP) and least square support vector machine regression (LSSVMR), regarding correlation coefficient of true value and predicted value as evaluation criterion, eventually, LSSVMR was confirmed as the appropriate method for modeling of greenhouse cucumber disease and insect damage chlorophyll fluorescence spectrum analysis.

  15. Channelized broadband signal spectrum analysis based on weighted overlap-add structure.

    PubMed

    Guo, Lianping; Jiang, Jun; Tan, Feng; Pan, Huiqing; Zhang, Peng; Zeng, Hao; Bai, Lihong

    2016-10-01

    The digital channelization technology has been applied in many electronic areas, and the real-time broadband spectrum analysis has been the research hotspot in the area of signal processing. This paper introduces the channelized broadband signal spectrum analysis method. Based on the weighted overlap-add (WOLA) structure, this method divides the input broadband signal into several sub-bands or channels, and then downconverts and decimates the sub-band signals to obtain the baseband signals with a low sampling rate. The spectrum analysis results of the input broadband signal are achieved by conducting further decimation, fast Fourier transform and spectrum splicing to the baseband signals. The Matlab simulation results verify the correctness of the WOLA structure, and finally, an experimental platform is designed in detail to verify the practicability of this broadband spectrum analysis method.

  16. Channelized broadband signal spectrum analysis based on weighted overlap-add structure

    NASA Astrophysics Data System (ADS)

    Guo, Lianping; Jiang, Jun; Tan, Feng; Pan, Huiqing; Zhang, Peng; Zeng, Hao; Bai, Lihong

    2016-10-01

    The digital channelization technology has been applied in many electronic areas, and the real-time broadband spectrum analysis has been the research hotspot in the area of signal processing. This paper introduces the channelized broadband signal spectrum analysis method. Based on the weighted overlap-add (WOLA) structure, this method divides the input broadband signal into several sub-bands or channels, and then downconverts and decimates the sub-band signals to obtain the baseband signals with a low sampling rate. The spectrum analysis results of the input broadband signal are achieved by conducting further decimation, fast Fourier transform and spectrum splicing to the baseband signals. The Matlab simulation results verify the correctness of the WOLA structure, and finally, an experimental platform is designed in detail to verify the practicability of this broadband spectrum analysis method.

  17. Analysis of Gamma-Band Activity from Human EEG Using Empirical Mode Decomposition

    PubMed Central

    Amo, Carlos; de Santiago, Luis; Barea, Rafael; López-Dorado, Almudena; Boquete, Luciano

    2017-01-01

    The purpose of this paper is to determine whether gamma-band activity detection is improved when a filter, based on empirical mode decomposition (EMD), is added to the pre-processing block of single-channel electroencephalography (EEG) signals. EMD decomposes the original signal into a finite number of intrinsic mode functions (IMFs). EEGs from 25 control subjects were registered in basal and motor activity (hand movements) using only one EEG channel. Over the basic signal, IMF signals are computed. Gamma-band activity is computed using power spectrum density in the 30–60 Hz range. Event-related synchronization (ERS) was defined as the ratio of motor and basal activity. To evaluate the performance of the new EMD based method, ERS was computed from the basic and IMF signals. The ERS obtained using IMFs improves, from 31.00% to 73.86%, on the original ERS for the right hand, and from 22.17% to 47.69% for the left hand. As EEG processing is improved, the clinical applications of gamma-band activity will expand. PMID:28468250

  18. Analysis of Gamma-Band Activity from Human EEG Using Empirical Mode Decomposition.

    PubMed

    Amo, Carlos; de Santiago, Luis; Barea, Rafael; López-Dorado, Almudena; Boquete, Luciano

    2017-04-29

    The purpose of this paper is to determine whether gamma-band activity detection is improved when a filter, based on empirical mode decomposition (EMD), is added to the pre-processing block of single-channel electroencephalography (EEG) signals. EMD decomposes the original signal into a finite number of intrinsic mode functions (IMFs). EEGs from 25 control subjects were registered in basal and motor activity (hand movements) using only one EEG channel. Over the basic signal, IMF signals are computed. Gamma-band activity is computed using power spectrum density in the 30-60 Hz range. Event-related synchronization (ERS) was defined as the ratio of motor and basal activity. To evaluate the performance of the new EMD based method, ERS was computed from the basic and IMF signals. The ERS obtained using IMFs improves, from 31.00% to 73.86%, on the original ERS for the right hand, and from 22.17% to 47.69% for the left hand. As EEG processing is improved, the clinical applications of gamma-band activity will expand.

  19. Performance of lanthanide-halide scintillation detectors in prompt gamma analysis of bulk samples

    NASA Astrophysics Data System (ADS)

    Al-Anezi, Mohammad Saleh

    Performance tests of cylindrical 3" x 3" (LaBr3:Ce and LaCl3:Ce) and 5" x 5" (BGO) detectors were carried out to detect low energy prompt gamma-rays from boron contaminated water samples using a newly designed portable neutron generator-based Prompt Gamma Neutron Activation Analysis (PGNAA) setup. Prompt gamma-rays were measured from water samples contaminated with 0.031 to 0.5 wt% boron. The experimental yield of boron prompt gamma-rays measured with LaBr3:Ce, LaCl3:Ce and BGO detectors based PGNAA setup were compared. An excellent agreement has been observed between the experimental and calculated yield of boron prompt gamma ray from water samples. Minimum detection concentrations (MDC)s of boron in water samples for LaBr3:Ce, LaCl3:Ce and BGO detectors were determined to be: 30 ± 9.3, 45 ± 16.4, 28 ± 8 (ppm) respecteviley which agree with each other within statistical uncertainty.

  20. Southern Analysis of Genomic Alterations in Gamma-Ray-Induced Aprt- Hamster Cell Mutants

    PubMed Central

    Grosovsky, Andrew J.; Drobetsky, Elliot A.; deJong, Pieter J.; Glickman, Barry W.

    1986-01-01

    The role of genomic alterations in mutagenesis induced by ionizing radiation has been the subject of considerable speculation. By Southern blotting analysis we show here that 9 of 55 (approximately 1/6) gamma-ray-induced mutants at the adenine phosphoribosyl transferase (aprt) locus of Chinese hamster ovary (CHO) cells have a detectable genomic rearrangement. These fall into two classes: intragenic deletions and chromosomal rearrangements. In contrast, no major genomic alterations were detected among 67 spontaneous mutants, although two restriction site loss events were observed. Three gamma-ray-induced mutants were found to be intragenic deletions; all may have identical break-points. The remaining six gamma-ray-induced mutants demonstrating a genomic alteration appear to be the result of chromosomal rearrangements, possibly translocation or inversion events. None of the remaining gamma-ray-induced mutants showed any observable alteration in blotting pattern indicating a substantial role for point mutation in gamma-ray-induced mutagenesis at the aprt locus. PMID:3013724

  1. Analysis of gamma-ray dosimetry experiments in the zero power MINERVE facility

    SciTech Connect

    Amharrak, H.; Di Salvo, J.; Lyoussi, A.; Roche, A.; Masson-Fauchier, M.; Bosq, J. C.; Carette, M.

    2011-07-01

    The objective of this study is to develop nuclear heating measurement methods in zero power experimental reactors. These developments contribute to the qualification of photonics calculation schemes for the assessment of gamma heating in the future Jules Horowitz Material Testing Reactor. This paper presents the analysis of thermoluminescent detector (TLD) experiments in the UO{sub 2} core of the MINERVE Research Reactor at the French Alternative Energies and Atomic Energy Commission center in Cadarache. The experimental sources of uncertainty in the gamma dose have been reduced by improving the measurement conditions and the repeatability of the calibration step for each individual TLD. The interpretation of these measurements needs to take into account the calculation of cavity correction factors related to calibration and irradiation configurations, as well as neutron correction calculations. These calculations are based on Monte Carlo simulations of neutron-gamma and gamma-electron transport coupled particles. The comparison between calculated and measured integral gamma-ray absorbed doses in the aluminum material surrounding the TLD shows that calculations slightly overestimate the measurement, with a calculated versus experimental ratio equal to 1.04 {+-} 5.7 % (k=2). (authors)

  2. Analysis of Neutron Induced Gamma Activity in Lowbackground Ge - Spectroscopy Systems

    NASA Astrophysics Data System (ADS)

    Jovančević, Nikola; Krmar, Midrag

    Neutron interactions with materials of Ge-spectroscopy systems are one of the main sources of background radiation in low-level gamma spectroscopy measurements. Because of that detailed analysis of neutron induced gamma activity in low-background Ge-spectroscopy systems was done. Two HPGe detectors which were located in two different passive shields: one in pre-WW II made iron and the second in commercial low background lead were used in the experiment. Gamma lines emitted after neutron capture, as well as after inelastic scattering on the germanium crystal and shield materials (lead, iron, hydrogen, NaI) were detected and then analyzed. The thermal and fast neutron fluxes were calculated and their values were compared for the two different kinds of detector shield. The relative intensities of several gamma lines emitted after the inelastic scattering of neutrons (created by cosmic muons) in 56Fe were report. These relative intensities of detected gamma lines of 56Fe are compared with the results collected in the same iron shield by the use of the 252Cf neutrons.

  3. Prompt gamma-ray analysis of chlorine in superpozz cement concrete

    NASA Astrophysics Data System (ADS)

    Naqvi, A. A.; Kalakada, Zameer; Al-Matouq, Faris A.; Maslehuddin, M.; Al-Amoudi, O. S. B.; ur-Rehman, Khateeb

    2012-11-01

    The chlorine concentration in Superpozz (SPZ) cement concrete was analyzed using a newly designed prompt gamma-ray neutron activation (PGNAA) setup utilizing a portable neutron generator. The setup, which mainly consists of a neutron source along with its moderator placed side by side with a shielded gamma-ray detector, allows determining chloride concentration in a concrete structure from one side. The setup has been tested through chlorine detection in chloride-contaminated Superpozz (SPZ) cement concrete specimens using 6.11 and 2.86±3.10 MeV chlorine prompt gamma-rays. The optimum 0.032±0.012 wt% value of Minimum Detectable Concentration (MDC) of chlorine in SPZ cement concrete measured in this study shows a successful application of a portable neutron generator in chloride analysis of concrete structure for corrosion studies.

  4. A new method of intracranial pressure monitoring by EEG power spectrum analysis.

    PubMed

    Chen, Hui; Wang, Jian; Mao, Sizhong; Dong, Weiwei; Yang, Hao

    2012-07-01

    To investigate the feasibility of Electroencephalogram (EEG) power spectrum analysis as a noninvasive method for monitoring intracranial pressure (ICP). The EEG signals were recorded in 62 patients (70 cases) with central nervous system (CNS) disorders in our hospital. By using self-designed software, EEG power spectrum analysis was conducted and pressure index (PI) was calculated automatically. Intracranial pressure was measured by lumbar puncture (LP). We found a significant negative correlation between PI and ICP (r = -0.849, p < 0.01). The PI obtained from EEG analysis is correlated with ICP. Analysis of specific parameters from EEG power spectrum might reflect the ICP.

  5. Analysis of the backscatter spectrum in an ionospheric modification experiment

    NASA Technical Reports Server (NTRS)

    Kim, H.

    1973-01-01

    Predictions of the backscatter spectrum are compared, including effects of ionospheric inhomogeneity with experimental observations of incoherent backscatter from an artificially heated region. Calculations show that the strongest backscatter echo received is not, in fact, from the reflection level, but from a region some distance below (about 0.5 km for an experiment carried out at Arecibo), where the pump wave from a HF transmitter approximately 100 kW) is below the threshold for parametric amplification. By taking the standing wave pattern of the pump into account, asymmetry is explained of the up-shifted and down-shifted plasma lines in the backscatter spectrum, and the several peaks typically observed in the region of the spectrum near the HF transmitter frequency.

  6. Improvement of the edge rotation diagnostic spectrum analysis via simulation.

    PubMed

    Luo, J; Zhuang, G; Cheng, Z F; Zhang, X L; Hou, S Y; Cheng, C

    2014-11-01

    The edge rotation diagnostic (ERD) system has been developed on the Joint Texas Experimental Tokamak to measure the edge toroidal rotation velocity by observing the shifted wavelength of carbon V (C V 227.09 nm). Since the measured spectrum is an integrated result along the viewing line from the plasma core to the edge, a method via simulation has been developed to analyze the ERD spectrum. With the necessary parameters such as C V radiation profile and the ion temperature profile, a local rotation profile at the normalized minor radius of 0.5-1 is obtained.

  7. Improvement of the edge rotation diagnostic spectrum analysis via simulation

    SciTech Connect

    Luo, J.; Zhuang, G. Cheng, Z. F.; Zhang, X. L.; Hou, S. Y.; Cheng, C.

    2014-11-15

    The edge rotation diagnostic (ERD) system has been developed on the Joint Texas Experimental Tokamak to measure the edge toroidal rotation velocity by observing the shifted wavelength of carbon V (C V 227.09 nm). Since the measured spectrum is an integrated result along the viewing line from the plasma core to the edge, a method via simulation has been developed to analyze the ERD spectrum. With the necessary parameters such as C V radiation profile and the ion temperature profile, a local rotation profile at the normalized minor radius of 0.5-1 is obtained.

  8. Prevalence of Schizophrenia Spectrum Disorders in Average-IQ Adults with Autism Spectrum Disorders: A Meta-analysis.

    PubMed

    Lugo Marín, Jorge; Alviani Rodríguez-Franco, Montserrat; Mahtani Chugani, Vinita; Magán Maganto, María; Díez Villoria, Emiliano; Canal Bedia, Ricardo

    2017-10-04

    Since their separation as independent diagnostics, autism spectrum disorders (ASD) and schizophrenia spectrum disorders (SSD) have been conceptualized as mutually exclusive disorders. Similarities between both disorders can lead to misdiagnosis, especially when it comes to average-IQ adults who were not identified during childhood. The aim of this review was to examine the occurrence of SSD in average-IQ adults with ASD. Electronic and manual searches identified a total of 278 references, of which 10 were included in a meta-analysis. The pooled prevalence of SSD in the total ASD sample was close to 6%, pointing to a high co-occurrence of the two conditions. Further research is needed to determine the factors that predispose members of this population to the emergence of psychotic disorders.

  9. 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

  10. The gamma ray spectrometer for the Solar Maximum Mission

    NASA Technical Reports Server (NTRS)

    Forrest, D. J.; Chupp, E. L.; Ryan, J. M.; Cherry, M. L.; Gleske, I. U.; Reppin, C.; Pinkau, K.; Rieger, E.; Kanbach, G.; Kinzer, R. L.

    1980-01-01

    The paper describes an actively shielded, multicrystal scintillation spectrometer for measurement of the solar gamma ray flux used by the Solar Maximum Mission Gamma Ray Experiment. The instrument provides a 476-channel pulse height spectrum every 16.38 s over the 0.3-9 MeV energy range; the gamma ray spectral analysis can be extended to at least 15 MeV on command. The instrument is designed to measure the intensity, energy, and Doppler shift of narrow gamma ray lines, the intensity of extremely broadened lines, and the photon continuum.

  11. ART-XC: A Medium-energy X-ray Telescope System for the Spectrum-R-Gamma Mission

    NASA Technical Reports Server (NTRS)

    Arefiev, V.; Pavlinsky, M.; Lapshov, I.; Thachenko, A.; Sazonov, S.; Revnivtsev, M.; Semena, N.; Buntov,M.; Vikhlinin, A.; Gubarev, M.; hide

    2008-01-01

    The ART-XC instrument is an X-ray grazing-incidence telescope system in an ABRIXAS-type optical configuration optimized for the survey observational mode of the Spectrum-RG astrophysical mission which is scheduled to be launched in 2011. ART-XC has two units, each equipped with four identical X-ray multi-shell mirror modules. The optical axes of the individual mirror modules are not parallel but are separated by several degrees to permit the four modules to share a single CCD focal plane detector, 1/4 of the area each. The 450-micron-thick pnCCD (similar to the adjacent eROSITA telescope detector) will allow detection of X-ray photons up to 15 keV. The field of view of the individual mirror module is about 18 x 18 arcminutes(exp 2) and the sensitivity of the ART-XC system for 4 years of survey will be better than 10(exp -12) erg s(exp -1) cm(exp -2) over the 4-12 keV energy band. This will allow the ART-XC instrument to discover several thousand new AGNs.

  12. ART-XC: a medium-energy x-ray telescope system for the Spectrum-R-Gamma mission

    NASA Astrophysics Data System (ADS)

    Arefiev, V.; Pavlinsky, M.; Lapshov, I.; Tkachenko, A.; Sazonov, S.; Revnivtsev, M.; Semena, N.; Buntov, M.; Vikhlinin, A.; Gubarev, M.; O'Dell, S.; Ramsey, B.; Romaine, S.; Swartz, D.; Weisskopf, M.; Hasinger, G.; Predehl, P.; Grigorovich, S.; Litvin, D.; Meidinger, N.; Strüder, L. W.

    2008-07-01

    The ART-XC instrument is an X-ray grazing-incidence telescope system in an ABRIXAS-type optical configuration optimized for the survey observational mode of the Spectrum-RG astrophysical mission which is scheduled to be launched in 2011. ART-XC has two units, each equipped with four identical X-ray multi-shell mirror modules. The optical axes of the individual mirror modules are not parallel but are separated by several degrees to permit the four modules to share a single CCD focal plane detector, 1/4 of the area each. The 450-micron-thick pnCCD (similar to the adjacent eROSITA telescope detector) will allow the detection of X-ray photons up to 15 keV. The field of view of the individual mirror module is about 18×18 arcminutes2 and the sensitivity of the ART-XC system for 4 years of survey will be better than 10-12 erg s-1 cm-2 over the 4-12 keV energy band. This will allow the ART-XC instrument to discover several thousands new AGNs.

  13. The 235U(n,2n(gamma)) Yrast Partial Gamma-Ray Cross Sections: A Report on the 1998 -- 1999 GEANIE Data and Analysis Techniques

    SciTech Connect

    Younes, W; Becker, J A; Bernstein, L A; Garret, P E; McGrath, C A; McNabb, D P; Nelson, R O; Devlin, M; Fotiades, N; Johns, G D

    2000-09-01

    Measurements of partial {sup 235}U(n,2n{gamma}) {gamma}-ray cross sections have been carried out as a function of incident neutron energy using the GEANIE spectrometer at LANSCE/WNR. The yields of {gamma} rays resulting from the population of discrete levels in the residual nucleus {sup 234}U have been measured at incident neutron energies in the 1-20-MeV range. These data provide, with the aid of nuclear reaction modeling, a measurement of the {sup 235}U(n,2n) reaction cross section and serve as a proof of principle of the y-ray technique for the parallel 23gPu(n,2n) measurement [l]. This paper presents the analysis of the {gamma}-ray data and the extraction of partial {gamma}-ray cross sections as a function of incident neutron energy. Uncertainties associated with the spectroscopic analysis of the data and validation of the results are discussed in detail.

  14. VRF ("Visual RobFit") — nuclear spectral analysis with non-linear full-spectrum nuclide shape fitting

    NASA Astrophysics Data System (ADS)

    Lasche, George; Coldwell, Robert; Metzger, Robert

    2017-09-01

    A new application (known as "VRF", or "Visual RobFit") for analysis of high-resolution gamma-ray spectra has been developed using non-linear fitting techniques to fit full-spectrum nuclide shapes. In contrast to conventional methods based on the results of an initial peak-search, the VRF analysis method forms, at each of many automated iterations, a spectrum-wide shape for each nuclide and, also at each iteration, it adjusts the activities of each nuclide, as well as user-enabled parameters of energy calibration, attenuation by up to three intervening or self-absorbing materials, peak width as a function of energy, full-energy peak efficiency, and coincidence summing until no better fit to the data can be obtained. This approach, which employs a new and significantly advanced underlying fitting engine especially adapted to nuclear spectra, allows identification of minor peaks that are masked by larger, overlapping peaks that would not otherwise be possible. The application and method are briefly described and two examples are presented.

  15. DoD Spectrum Management: A Critical Analysis

    DTIC Science & Technology

    2008-06-01

    29  13. IRAC Council...Administration (NTIA) Interdepartmental Radio Advisory Committee ( IRAC ). Each nation manages its own spectrum bands in a similar manner since the...Services continue to work with NTIA and the IRAC Frequency Assignment Subcommittee (FAS) to reduce the processing times. Figure 4 Frequency

  16. Factor Analysis of the Autism Spectrum Screening Questionnaire

    ERIC Educational Resources Information Center

    Posserud, Britt; Lundervold, Astri J.; Steijnen, Maaike C.; Verhoeven, Sophie; Stormark, Kjell Morten; Gillberg, Christopher

    2008-01-01

    The present study investigated the factor structure of parent and teacher Autism Spectrum Screening Questionnaire (ASSQ) in a population of 7-9 years old children. For validation purposes, factors derived were correlated with results on the Strengths and Difficulties Questionnaire (SDQ). A three-factor solution was identified on both parent and…

  17. Dream Content Analysis in Persons with an Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Daoust, Anne-Marie; Lusignan, Felix-Antoine; Braun, Claude M. J.; Mottron, Laurent; Godbout, Roger

    2008-01-01

    Dream questionnaires were completed by 28 young adults with autism spectrum disorder (ASD) participants. Seventy-nine typically developed individual served as the control group. In a subset of 17 persons with ASD and 11 controls matched for verbal IQ, dream narratives were obtained following REM sleep awakenings in a sleep laboratory.…

  18. Dream Content Analysis in Persons with an Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Daoust, Anne-Marie; Lusignan, Felix-Antoine; Braun, Claude M. J.; Mottron, Laurent; Godbout, Roger

    2008-01-01

    Dream questionnaires were completed by 28 young adults with autism spectrum disorder (ASD) participants. Seventy-nine typically developed individual served as the control group. In a subset of 17 persons with ASD and 11 controls matched for verbal IQ, dream narratives were obtained following REM sleep awakenings in a sleep laboratory.…

  19. Three-dimensional acousto-optic spectrum analysis

    NASA Technical Reports Server (NTRS)

    Ansari, Homayoon; Metscher, Brian; Lesh, James R.

    1990-01-01

    A three-dimensional acoustooptic spectrum analyzer with subhertz resolution is demonstrated experimentally. The first and second dimensions are the two spatial dimensions of the output detector array, and the third dimension is time as sampled by the detector array frame rate. A superfine resolution of 0.12 Hz has been achieved.

  20. Analysis and Interpretation of Gamma-Ray Burst Continuum Spectral Evolution with BATSE Data

    NASA Astrophysics Data System (ADS)

    Crider, Anthony Wayne

    1999-10-01

    Once a day, a flash of gamma-rays erupts somewhere in space and is detected by an international fleet of satellites. Since their first detection over a quarter century ago, these gamma-ray bursts have puzzled researchers who could not determine their distance, emission mechanism, or progenitor. Much of this confusion arose as theorists attempted to create a single model to explain what we now believe are at least two, and probably more, populations of gamma-ray transients. Within the past two years, thanks largely to the Dutch-Italian satellite BeppoSAX, astronomers discovered that bursts have multiwavelength fading afterglows. This helped them determine that most gamma-ray bursts are from distant galaxies. However, it did not answer the questions regarding the emission mechanism or the progenitor. We place constraints on the emission mechanism by closely examining the spectral evolution of gamma-ray bursts observed by the American instrument BATSE. From a sample of 41 distinct pulses in 26 bright gamma-ray bursts, we have determined that the pulses appear to be radiatively cooling. We also studied the evolving spectral shape in 79 bursts. In particular, we found that both the range and evolution of the spectral index below the spectral break conflict with the predictions of a popular synchrotron shock model. They instead suggest inverse Comptonization in a hybrid thermal plus nonthermal plasma as the emission mechanism. With our Monte Carlo codes, we have begun the generation of a library of inverse Compton spectra. Using them, we have made preliminary fits to two bursts with prompt multiwavelength data. The characteristic "terrace-shaped" Compton spectrum is evident in both using BATSE data alone. This shape appears to be confirmed for the January 1, 1997 burst using BeppoSAX X-ray data and for the January 23, 1999 burst using optical data from the ground-based robotic telescope, ROTSE. Both bursts appear to be enshrouded in a material with a high initial Thomson

  1. Rotational Doppler shift for electromagnetic waves carrying orbital angular momentum based on spectrum analysis

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Wang, Gang

    2017-03-01

    We investigate the rotational Doppler effect for the electromagnetic wave carrying orbital angular momentum (OAM) with a method based on spectrum analysis, which is appropriate for both optics and free-space radio cases. We find that the frequency spectrum received is the convolution of emission spectrum and a discrete spectrum about OAM states, and verify it in the numerical simulations as well. This discovery makes it possible to distinguish the linear and rotational Doppler shift, and is helpful to developments of remote sensing and velocimetry in radar.

  2. Feasibility study for the quantification of total protein content by multiple prompt gamma-ray analysis.

    PubMed

    Toh, Y; Murakami, Y; Furutaka, K; Kimura, A; Koizumi, M; Hara, K; Kin, T; Nakamura, S; Harada, H

    2012-06-01

    Protein is an important nutrient in foods. The classical nitrogen analysis method is the Kjeldahl technique, which is time-consuming and inconvenient. As a convenient method to quantify protein content in biological samples, the feasibility of application of multiple prompt gamma-ray analysis (MPGA) to the quantification was studied. Results for protein content are reported for several reference materials and prove the method to be reliable.

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

    PubMed

    Kavetskiy, A; Yakubova, G; Torbert, H A; Prior, S A

    2015-02-01

    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 produced measurements in agreement with theoretical considerations. The continuous NGA mode was twice as fast and just as accurate as the pulse mode, thus this mode was preferable for routine soil carbon analysis.

  4. [Research on the method of copper converting process determination based on emission spectrum analysis].

    PubMed

    Li, Xian-xin; Liu, Wen-qing; Zhang, Yu-jun; Si, Fu-qi; Dou, Ke; Wang, Feng-ping; Huang, Shu-hua; Fang, Wu; Wang, Wei-qiang; Huang, Yong-feng

    2012-05-01

    A method of copper converting process determination based on PbO/PbS emission spectrum analysis was described. According to the known emission spectrum of gas molecules, the existence of PbO and PbS was confirmed in the measured spectrum. Through the field experiment it was determined that the main emission spectrum of the slag stage was from PbS, and the main emission spectrum of the copper stage was from PbO. The relative changes in PbO/PbS emission spectrum provide the method of copper converting process determination. Through using the relative intensity in PbO/PbS emission spectrum the copper smelting process can be divided into two different stages, i.e., the slag stage (S phase) and the copper stage (B phase). In a complete copper smelting cycle, a receiving telescope of appropriate view angle aiming at the converter flame, after noise filtering on the PbO/PbS emission spectrum, the process determination agrees with the actual production. Both the theory and experiment prove that the method of copper converting process determination based on emission spectrum analysis is feasible.

  5. Molecular diagnosis of A gamma hereditary persistence of fetal hemoglobin using polymerase chain reaction and oligonucleotide analysis.

    PubMed

    Gottardi, E; Alfarano, A; Serra, A; Sciarratta, G; Bertero, M T; Saglio, G; Camaschella, C

    1990-01-01

    By combining the polymerase chain reaction (PCR) of the gamma globin gene promoters with synthetic oligonucleotide analysis we have diagnosed the -196 C----T and the -117 G----A substitutions in heterozygous carriers of non deletional A gamma HPFH from two unrelated Italian families. The identification of the beta-thalassemic defect in a compound heterozygote for -196 A gamma HPFH/beta thalassemia allows us to discuss the effect of this gamma promoter mutation on the globin chain synthetic pattern, and to make a comparison with the mutation at the -117 position.

  6. Soft x-ray calibration of the Co/C multilayer mirrors for the Objective Crystal Spectrometer on the Spectrum Roentgen-Gamma satellite

    NASA Astrophysics Data System (ADS)

    Abdali, Salim; Tarrio, Charles; Christensen, Finn E.; Schnopper, Herbert W.

    1996-07-01

    The objective crystal spectrometer (OXS) on the forthcoming Spectrum-Roentgen-Gamma satellite is designed to carry three kinds of crystals: LiF(220), Si(111) and RAP(001), placed in front of the SODART telescope. Thirty six super polished (RMS roughness < 0.1nm) Si(111) substrates were coated with 65-80 periods of Co/C multilayers using electron beam evaporation deposition combined with ion polishing for the metal layers. These crystals are to be used in the energy band immediately below the C-K absorption edge of 0.284 keV. Because the crystals are to be assembled as one crystal on the OXS, the reflectivity performance as a function of energy and angle of incidence of all crystals has been measured using line radiation from an x-ray tube which provides 1.487 keV and 0.277 keV and using synchrotron radiation from 0.16 keV to 0.28 keV at the Synchrotron Ultraviolet Radiation electron storage ring a t the National Institute of Standards and Technology. The results from these measurements are discussed.

  7. Non-Destructive Bulk Soil Analysis for a Chlorinated Compound using Prompt Gamma-Ray Neutron Activation Analysis

    SciTech Connect

    Sigg, R.A.

    1999-04-19

    A prompt gamma-ray neutron activation analysis (PGNAA) system was evaluated for the quantification of chlorinated compounds in soil. The system evaluation was divided into two phases. In phase one, the response of an n-type HPGe detector (20 percent relative efficiency) to point sources of 60Co and 152Eu was determined experimentally and used to calibrate an MCNP4a model of the detector. The refined MCNP4a detector model can predict the absolute peak detection efficiency within 7 percent in the energy range of 120 - 1400 keV. In phase two, a PGNAA system consisting of a light-water moderated 252Cf (1.06 mg) neutron source, and the shielded and collimated HPGe detector was used to collect prompt gamma-ray spectra from Savannah River Site (SRS) soil spiked with chlorine. The experimental system response was used to calculate the minimum detectable concentration of chlorine in the SRS soil for a 1800 sec. irradiation as 2200 mg/g based on the analysis of the 788 keV gamma-ray. MCNP4a was used to predict the PGNAA system response, which was accomplished by analyzing the neutron and gamma ray transport components separately. In the energy range of 788 to 6110 keV, the MCNP4a predictions were generally within 60 percent of the calculated probability of detection of a prompt gamma ray based on the experimental data.

  8. 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.

  9. 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

  10. Gamma Ray Observatory (GRO) OBC attitude error analysis

    NASA Technical Reports Server (NTRS)

    Harman, R. R.

    1990-01-01

    This analysis involves an in-depth look into the onboard computer (OBC) attitude determination algorithm. A review of TRW error analysis and necessary ground simulations to understand the onboard attitude determination process are performed. In addition, a plan is generated for the in-flight calibration and validation of OBC computed attitudes. Pre-mission expected accuracies are summarized and sensitivity of onboard algorithms to sensor anomalies and filter tuning parameters are addressed.

  11. Extended analysis of fifth spectrum of bromine: Br V

    NASA Astrophysics Data System (ADS)

    Riyaz, A.; Tauheed, A.; Rahimullah, K.

    2014-11-01

    The fifth spectrum of bromine (Br V) has been studied in the 200-2400 Å wavelength region. The spectrum was photographed on a 3-m normal incidence vacuum spectrograph at the St. Francis Xavier University, Antigonish (Canada) and 6.65-m grazing incidence spectrograph at the Zeeman laboratory (Amsterdam). The light sources used were a triggered spark and sliding spark. The ground configuration of Br V is 4s24p. The excited configurations 4s4p2+4s2(4d+5d+5s+6s+7s+5g+6g)+4s4p(5p+4f)+4p24d in the even parity system and the 4p3+4s2(5p+6p+7p+4f)+4s4p4d+4s4p5s configurations in the odd parity system have been studied. Relativistic Hartree-Fock (HFR) and least squares fitted (LSF) parametric calculations have been used to interpret the observed spectrum. 99 levels of Br V have now been established, 43 being new. Among 394 classified spectral lines, 181 are newly classified. The level 4s27s 2S1/2 is revised. We estimate the accuracy of our measured wavelengths for sharp and unblended lines to be±0.005 Å. The ionization limit is determined as 479,657±200 cm-1 (59.470±0.025 eV).

  12. Analysis of neutron and gamma-ray streaming along the maze of NRCAM thallium production target room.

    PubMed

    Raisali, G; Hajiloo, N; Hamidi, S; Aslani, G

    2006-08-01

    Study of the shield performance of a thallium-203 production target room has been investigated in this work. Neutron and gamma-ray equivalent dose rates at various points of the maze are calculated by simulating the transport of streaming neutrons, and photons using Monte Carlo method. For determination of neutron and gamma-ray source intensities and their energy spectrum, we have applied SRIM 2003 and ALICE91 computer codes to Tl target and its Cu substrate for a 145 microA of 28.5 MeV protons beam. The MCNP/4C code has been applied with neutron source term in mode n p to consider both prompt neutrons and secondary gamma-rays. Then the code is applied for the prompt gamma-rays as the source term. The neutron-flux energy spectrum and equivalent dose rates for neutron and gamma-rays in various positions in the maze have been calculated. It has been found that the deviation between calculated and measured dose values along the maze is less than 20%.

  13. Diffuse galactic continuum emission measured by COMPTEL and the cosmic-ray electron spectrum

    NASA Technical Reports Server (NTRS)

    Strong, A. W.; Diehl, R.; Schoenfelder, V.; Varendorff, M.; Youssefi, G.; Bloemen, H.; Hermsen, W.; De Vries, C.; Morris, D.; Stacy, J. G.

    1994-01-01

    Diffuse galactic continuum gamma-ray emission in the 0.75-30 MeV range from the inner Galaxy has been studied using data from COMPTEL on the Compton Gamma-Ray Observatory. Observations of the inner Galaxy from the Sky Survey have been used. The imaging properties of COMPTEL enable spatial analysis of the gamma-ray distribution using model fitting. A model based on atomic and molecular gas distributions in the Galaxy has been used to derive the emissivity spectrum of the gamma-ray emission and this spectrum is compared with theoretical estimates of bremsstrahlung emission from cosmic-ray electrons.

  14. Analysis method for Thomson scattering diagnostics in GAMMA 10/PDX

    NASA Astrophysics Data System (ADS)

    Ohta, K.; Yoshikawa, M.; Yasuhara, R.; Chikatsu, M.; Shima, Y.; Kohagura, J.; Sakamoto, M.; Nakasima, Y.; Imai, T.; Ichimura, M.; Yamada, I.; Funaba, H.; Minami, T.

    2016-11-01

    We have developed an analysis method to improve the accuracies of electron temperature measurement by employing a fitting technique for the raw Thomson scattering (TS) signals. Least square fitting of the raw TS signals enabled reduction of the error in the electron temperature measurement. We applied the analysis method to a multi-pass (MP) TS system. Because the interval between the MPTS signals is very short, it is difficult to separately analyze each Thomson scattering signal intensity by using the raw signals. We used the fitting method to obtain the original TS scattering signals from the measured raw MPTS signals to obtain the electron temperatures in each pass.

  15. Non destructive multi elemental analysis using prompt gamma neutron activation analysis techniques: Preliminary results for concrete sample

    SciTech Connect

    Dahing, Lahasen Normanshah; Yahya, Redzuan; Yahya, Roslan; Hassan, Hearie

    2014-09-03

    In this study, principle of prompt gamma neutron activation analysis has been used as a technique to determine the elements in the sample. The system consists of collimated isotopic neutron source, Cf-252 with HPGe detector and Multichannel Analysis (MCA). Concrete with size of 10×10×10 cm{sup 3} and 15×15×15 cm{sup 3} were analysed as sample. When neutrons enter and interact with elements in the concrete, the neutron capture reaction will occur and produce characteristic prompt gamma ray of the elements. The preliminary result of this study demonstrate the major element in the concrete was determined such as Si, Mg, Ca, Al, Fe and H as well as others element, such as Cl by analysis the gamma ray lines respectively. The results obtained were compared with NAA and XRF techniques as a part of reference and validation. The potential and the capability of neutron induced prompt gamma as tool for multi elemental analysis qualitatively to identify the elements present in the concrete sample discussed.

  16. Soil carbon analysis using gamma rays induced by neutrons

    USDA-ARS?s Scientific Manuscript database

    Agronomy is a research field where various physics concepts and experimental methods are widely used, particularly in agro-chemistry and soil elemental analysis. The evolution of methodology and instrumentation of nuclear physics combined with the availability of not highly expensive commercial prod...

  17. Photoacoustic spectrum analysis for microstructure characterization in biological tissue: A feasibility study

    NASA Astrophysics Data System (ADS)

    Xu, Guan; Dar, Irfaan A.; Tao, Chao; Liu, Xiaojun; Deng, Cheri X.; Wang, Xueding

    2012-11-01

    This study investigates the feasibility of characterizing the microstructures within a biological tissue by analyzing the frequency spectrum of the photoacoustic signal from the tissue. Hypotheses are derived from theoretical analyses on the relationships between the dimensions/concentrations of the photoacoustic sources within the region-of-interest and the linear model fitted to the power spectra of photoacoustic signals. The hypotheses are validated, following the procedures of ultrasound spectrum analysis, by simulations and experiments with phantoms fabricated by embedding the polyethylene microspheres in porcine gelatin, indicating that photoacoustic spectrum analysis could be a potential tool for characterizing microstructures in biological samples.

  18. Photoacoustic spectrum analysis for microstructure characterization in biological tissue: A feasibility study

    PubMed Central

    Xu, Guan; Dar, Irfaan A.; Tao, Chao; Liu, Xiaojun; Deng, Cheri X.; Wang, Xueding

    2012-01-01

    This study investigates the feasibility of characterizing the microstructures within a biological tissue by analyzing the frequency spectrum of the photoacoustic signal from the tissue. Hypotheses are derived from theoretical analyses on the relationships between the dimensions/concentrations of the photoacoustic sources within the region-of-interest and the linear model fitted to the power spectra of photoacoustic signals. The hypotheses are validated, following the procedures of ultrasound spectrum analysis, by simulations and experiments with phantoms fabricated by embedding the polyethylene microspheres in porcine gelatin, indicating that photoacoustic spectrum analysis could be a potential tool for characterizing microstructures in biological samples. PMID:23284178

  19. Photoacoustic spectrum analysis for microstructure characterization in biological tissue: A feasibility study.

    PubMed

    Xu, Guan; Dar, Irfaan A; Tao, Chao; Liu, Xiaojun; Deng, Cheri X; Wang, Xueding

    2012-11-26

    This study investigates the feasibility of characterizing the microstructures within a biological tissue by analyzing the frequency spectrum of the photoacoustic signal from the tissue. Hypotheses are derived from theoretical analyses on the relationships between the dimensions/concentrations of the photoacoustic sources within the region-of-interest and the linear model fitted to the power spectra of photoacoustic signals. The hypotheses are validated, following the procedures of ultrasound spectrum analysis, by simulations and experiments with phantoms fabricated by embedding the polyethylene microspheres in porcine gelatin, indicating that photoacoustic spectrum analysis could be a potential tool for characterizing microstructures in biological samples.

  20. Analysis of high resolution satellite data for cosmic gamma ray bursts

    NASA Technical Reports Server (NTRS)

    Imhof, W. L.; Nakano, G. H.; Reagan, J. B.

    1976-01-01

    Cosmic gamma ray bursts detected a germanium spectrometer on the low altitude satellite 1972-076B were surveyed. Several bursts with durations ranging from approximately 0.032 to 15 seconds were found and are tabulated. The frequency of occurrence/intensity distribution of these events was compared with the S to the -3/2 power curve of confirmed events. The longer duration events fall above the S to the -3/2 power curve of confirmed events, suggesting they are perhaps not all true cosmic gamma-ray bursts. The narrow duration events fall closely on the S to the -3/2 power curve. The survey also revealed several counting rate spikes, with durations comparable to confirmed gamma-ray bursts, which were shown to be of magnetospheric origin. Confirmation that energetic electrons were responsible for these bursts was achieved from analysis of all data from the complete payload of gamma-ray and energetic particle detectors on board the satellite. The analyses also revealed that the narrowness of the spikes was primarily spatial rather than temporal in character.

  1. 2-D Acousto-Optic Signal Processors for Simultaneous Spectrum Analysis and Direction Finding

    DTIC Science & Technology

    1990-11-01

    National Dfense Defence nationale 2-D ACOUSTO - OPTIC SIGNAL PROCESSORS FOR SIMULTANEOUS SPECTRUM ANALYSIS 00 AND DIRECTION FINDING (U) by NM Jim P.Y...Wr pdft .1w I0~1111191 3 05089 National DIfense Defence nationale 2-D ACOUSTO - OPTIC SIGNAL PROCESSORS FOR SIMULTANEOUS SPECTRUM ANALYSIS AND DIRECTION...Processing, J.T. Tippet et al., Eds., Chapter 38, pp. 715-748, MIT Press, Cambridge 1965. [6] A.E. Spezio," Acousto - optics for Electronic Warfare

  2. SPRT Analysis of Anomalies in Tritium Beta Decay Spectrum

    NASA Astrophysics Data System (ADS)

    Goldman, T.; Stephenson, G. J., Jr.

    1997-10-01

    The experimentally observed deviations from the Kurie plot near the endpoint of Tritium beta decay are opposite to those expected for the case of massive neutrinos. We reexamine(O. Kofoed-Hansen, Phil. Mag. 42), 1448 (1951). the possibility that these deviations are due to new hypoweak interactions. We find that enhancement above the massless neutrino beta spectrum does occur for all cases (scalar, pseudoscalar, tensor or right-handed currents), although it apparently cannot be large enough to explain the data and be consistent with other experimental constraints. Bounds on the strength of these non-standard model interactions are derived.

  3. Nuclear quadrupole resonance studies project. [spectrometer design and spectrum analysis

    NASA Technical Reports Server (NTRS)

    Murty, A. N.

    1978-01-01

    The participation of undergraduates in nuclear quadrupole resonance research at Grambling University was made possible by NASA grants. Expanded laboratory capabilities include (1) facilities for high and low temperature generation and measurement; (2) facilities for radio frequency generation and measurement with the modern spectrum analyzers, precision frequency counters and standard signal generators; (3) vacuum and glass blowing facilities; and (4) miscellaneous electronic and machine shop facilities. Experiments carried out over a five year period are described and their results analyzed. Theoretical studies on solid state crystalline electrostatic fields, field gradients, and antishielding factors are included.

  4. Search of a prompt gamma ray for chlorine analysis in a Portland cement sample

    NASA Astrophysics Data System (ADS)

    Naqvi, A. A.; Nagadi, M. M.; Kidwai, S.; Khateeb-ur-Rehman; Maslehuddin, M.

    2004-11-01

    Prompt Gamma Ray analysis of chlorine contaminated Portland cement samples have been carried out using an accelerator-based Prompt Gamma ray Neutron Activation Analysis setup. The chlorine concentration was measured over a range of 0.25-4 wt% using 1.165 MeV capture γ-rays from chlorine. The experimental results were compared with the results of Monte Carlo simulations and an excellent agreement was observed between the two results. Further theoretical study has shown that yield of the 1.165 MeV prompt γ-rays from chlorine is not very sensitive to variation in moisture contents of the Portland sample. An order of magnitude increase in sample moisture content resulted in only 16-20% increase in yield of 1.165 MeV prompt γ-rays.

  5. Stabilization of prompt gamma-ray neutron activation analysis (PGNAA) spectra from NaI detectors

    NASA Astrophysics Data System (ADS)

    Metwally, W. A.; Gardner, R. P.

    2004-06-01

    NaI detectors are still used frequently in industrial Prompt Gamma-Ray Neutron Activation Analysis applications such as in bulk material analysis. They have the advantages of being efficient for high-energy gamma rays, being relatively rugged, and being able to be used without cooling. When using NaI detectors, and consequently photomultiplier tubes, the quality of the data can drastically deteriorate through gain and zero shifts that result in spectral smearing due to temperature and/or counting rate changes. A new offline approach is presented to stabilize the NaI spectral drift. The approach is not sensitive to the cause of the drift and takes into account the NaI and ADC non-linearities. Peak resolution is improved substantially when this approach is used in the presence of spectral drift.

  6. Prompt-gamma neutron activation analysis facility for in vivo body composition studies in small animals.

    PubMed

    Stamatelatos, I E; Kasviki, K; Green, S; Gainey, M; Kalef-Ezra, J; Beddoe, A

    2004-05-01

    The design, calibration, dosimetry and performance evaluation of a prompt-gamma neutron activation analysis facility for in vivo body composition studies in small animals (i.e. rats or rabbits) is discussed. The system design was guided by Monte Carlo transport calculations using MCNP-4C code. A system was built and performance evaluation was made using a 185-GBq Pu-Be neutron source. Prompt-gamma rays produced by neutron capture reactions were detected by a combination of a NaI(Tl) scintillation and a HPGe semiconductor detectors. Nitrogen and chlorine were quantified by analysis of the 10.83-MeV and 6.11-MeV peaks, respectively. Appropriate corrections for the animal body size were determined. The facility described allows the in vivo determination of protein and extracellular space in sets of experimental animals.

  7. Determination of the optimum-size californium-252 neutron source for borehole capture gamma-ray analysis

    USGS Publications Warehouse

    Senftle, F.E.; Macy, R.J.; Mikesell, J.L.

    1979-01-01

    The fast- and thermal-neutron fluence rates from a 3.7 ??g 252Cf neutron source in a simulated borehole have been measured as a function of the source-to-detector distance using air, water, coal, iron ore-concrete mix, and dry sand as borehole media. Gamma-ray intensity measurements were made for specific spectral lines at low and high energies for the same range of source-to-detector distances in the iron ore-concrete mix and in coal. Integral gamma-ray counts across the entire spectrum were also made at each source-to-detector distance. From these data, the specific neutron-damage rate, and the critical count-rate criteria, we show that in an iron ore-concrete mix (low hydrogen concentration), 252Cf neutron sources of 2-40 ??g are suitable. The source size required for optimum gamma-ray sensitivity depends on the energy of the gamma ray being measured. In a hydrogeneous medium such as coal, similar measurements were made. The results show that sources from 2 to 20 ??g are suitable to obtain the highest gamma-ray sensitivity, again depending on the energy of the gamma ray being measured. In a hydrogeneous medium, significant improvement in sensitivity can be achieved by using faster electronics; in iron ore, it cannot. ?? 1979 North-Holland Publishing Co.

  8. Data acquisition and analysis software for gamma coincidence spectrometry

    PubMed Central

    Shetty, Martin; Şahin, Dağıstan

    2016-01-01

    Coincidence counting in neutron activation analysis has well-known advantages, most importantly improvement of detection limits. One obstacle to the wider use of this technique is the complexity of the data acquisition and reduction systems that it requires. The usual approaches to multi-detector data acquisition incur significant dead-time, involve redundant work in repeatedly developing limited tools and risk potential errors in low-level code. The paper describes progress made in developing a software framework to address these shortcomings. PMID:27325905

  9. Spectrum analysis of rectangular pulse in the atmospheric turbulence propagation

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Ni, Xiaolong; Jiang, Huilin; Wang, Junran; Liu, Zhi

    2016-11-01

    Atmospheric turbulence has a great influence on the performance of the atmospheric laser communication system reducing the signal to noise ratio (SNR) and increasing the bit error rate (BER). However, there is rarely study on the effect of atmospheric turbulence on the power spectrum of the rectangular pulse. In this paper, a spectral analyzing method is used to analyze the influence of atmospheric turbulence on the signal. An experiment of laser beam propagation characteristic is carried out on a 6km horizontal atmospheric link, the wavelength is 808 nm. The signal is 100MHz rectangular pulse. The waveform of the rectangular pulse is collected by the oscilloscope, and the power spectral density of the signal is calculated and analyzed by the method of periodogram. Experimental results show that the response and noise characteristics of the laser and photoelectric detector have a great influence on the signal power spectrum distribution which can increase the noise component in the 10^6 Hz frequency range. After the atmospheric turbulence propagation, the signal power decreases in the whole frequency range. However, as the existence of atmospheric turbulence, the signal power increases in the atmospheric turbulence characteristic frequency (tens to hundreds of Hz). The noise power increases in the high frequency range (10^7 10^8 Hz).

  10. Analysis of the Sub-Millimeter Rotational Spectrum of Urea

    NASA Astrophysics Data System (ADS)

    Thomas, Jessica R.; Fosnight, Alyssa M.; Medvedev, Ivan R.

    2013-06-01

    Urea, ((NH_{2})_{2}CO), has broad presence in biological species. As a byproduct of human metabolism, this molecule is commonly tested for in blood to diagnose different pathologies. Furthermore, urea is seen in interstellar medium and its detection could yield valuable insight into the mechanisms governing star formation. Despite the prevalence of urea, an absence exists in recorded frequencies of this molecule. The new generation of the sub-millimeter telescopes, such as ALMA, HERSCHEL, and SOFIA, allows detection of interstellar molecular spectra at unprecedented spatial and spectral resolutions. The knowledge of the precise frequencies of spectra transitions present in interstellar molecular clouds would alleviate the problem of spectral congestion and aid in molecular identification. This paper reports the most recent investigation of the submillimeter/terahertz gas phase spectrum of urea. Up until now, only the microwave laboratory spectrum of urea's vibrational ground state has been available. This paper reports the high-resolution spectra of urea in the sub-millimeter range, and extends the spectroscopic assignment of the rotational transitions in the vibrational ground state. Additionally, the assignment of the first vibrational state and tentative assignments of two additional vibrational states have been made.

  11. The clinical spectrum of phaeochromocytoma: analysis of 115 patients.

    PubMed

    Safwat, Ahmed S; Bissada, Nabil K; Seyam, Raouf M; Al Sobhi, Saif; Hanash, Kamal A

    2008-06-01

    To analyse the presentation, manifestations and outcome in consecutive patients with phaeochromocytoma, as this disease has a wide range of pathological and clinical expressions. The records of 115 patients with phaeochromocytoma were analysed retrospectively, recording the patients' age, sex, presenting symptoms and clinical signs, chemical, radiological and pathological findings and associated conditions. Of the 115 patients, 90 had adrenal tumours, 18 extra-adrenal and seven combined adrenal and extra-adrenal tumours. Ten patients had malignant and 105 had benign phaeochromocytoma. Eighty-six patients had sporadic and 29 had familial phaeochromocytoma, comprising eight with von Hippel-Lindau (VHL) disease, 17 with multiple endocrine neoplasia type II (MEN II) and four with von Recklinghausen disease. Two patients with sporadic phaeochromocytoma had Grave's disease. Ten patients (8.7%) had malignant phaeochromocytoma, of whom two had MEN II. A pregnant woman required prolonged intensive-care management before adrenalectomy and lost a fetus. Phaeochromocytoma is an interesting clinical entity with a wide spectrum of pathological and clinical manifestations. The diagnosis of phaeochromocytoma is confirmed by chemical methods, and located using imaging techniques, with computed tomography, magnetic resonance imaging and (131)I-meta-iodobenzyl guanidine radioisotope scanning being the most common. This series reflects the pathological and clinical spectrum of phaeochromocytoma. The presence of other manifestations of familial phaeochromocytoma influenced the presentation and prognosis of these patients.

  12. Primordial power spectrum: a complete analysis with the WMAP nine-year data

    SciTech Connect

    Hazra, Dhiraj Kumar; Shafieloo, Arman; Souradeep, Tarun E-mail: arman@apctp.org

    2013-07-01

    We have improved further the error sensitive Richardson-Lucy deconvolution algorithm making it applicable directly on the un-binned measured angular power spectrum of Cosmic Microwave Background observations to reconstruct the form of the primordial power spectrum. This improvement makes the application of the method significantly more straight forward by removing some intermediate stages of analysis allowing a reconstruction of the primordial spectrum with higher efficiency and precision and with lower computational expenses. Applying the modified algorithm we fit the WMAP 9 year data using the optimized reconstructed form of the primordial spectrum with more than 300 improvement in χ{sup 2}{sub eff} with respect to the best fit power-law. This is clearly beyond the reach of other alternative approaches and reflects the efficiency of the proposed method in the reconstruction process and allow us to look for any possible feature in the primordial spectrum projected in the CMB data. Though the proposed method allow us to look at various possibilities for the form of the primordial spectrum, all having good fit to the data, proper error-analysis is needed to test for consistency of theoretical models since, along with possible physical artefacts, most of the features in the reconstructed spectrum might be arising from fitting noises in the CMB data. Reconstructed error-band for the form of the primordial spectrum using many realizations of the data, all bootstrapped and based on WMAP 9 year data, shows proper consistency of power-law form of the primordial spectrum with the WMAP 9 data at all wave numbers. Including WMAP polarization data in to the analysis have not improved much our results due to its low quality but we expect Planck data will allow us to make a full analysis on CMB observations on both temperature and polarization separately and in combination.

  13. [Application of the racial algorithm in energy dispersive X-ray fluorescence overlapped spectrum analysis].

    PubMed

    Zeng, Guo-Qiang; Luo, Yao-Yao; Ge, Liang-Quan; Zhang, Qing-Xian; Gu, Yi; Cheng, Feng

    2014-02-01

    In the energy dispersive X-ray fluorescence spectrum analysis, scintillation detector such as NaI (Tl) detector usually has a low energy resolution at around 8%. The low energy resolution causes problems in spectral data analysis especially in the high background and low counts condition, it is very limited to strip the overlapped spectrum, and the more overlapping the peaks are, the more difficult to peel the peaks, and the qualitative and quantitative analysis can't be carried out because we can't recognize the peak address and peak area. Based on genetic algorithm and immune algorithm, we build a new racial algorithm which uses the Euclidean distance as the judgment of evolution, the maximum relative error as the iterative criterion to be put into overlapped spectrum analysis, then we use the Gaussian function to simulate different overlapping degrees of the spectrum, and the racial algorithm is used in overlapped peak separation and full spectrum simulation, the peak address deviation is in +/- 3 channels, the peak area deviation is no more than 5%, and it is proven that this method has a good effect in energy dispersive X-ray fluorescence overlapped spectrum analysis.

  14. Online Analysis of {gamma}-ray Sources with H.E.S.S

    SciTech Connect

    Fuessling, M.; Dalton, M.; Kerschhaggl, M.; Schwanke, U.; Jung, I.; Stegmann, C.

    2008-12-24

    Some of the {gamma}-ray sources detected by the H.E.S.S. experiment display irregular, often flare-like emission behaviour. A method to detect these outbursts as fast as possible is highly desirable. At H.E.S.S., first results from an offline analysis of pre-calibrated data can be obtained on-site approximately one hour after run end. We present a development and implementation of online analysis software that performs calibration and analysis of data at the time they are being taken allowing for a fast confirmation of observational results and appropriate reaction by the on-site shift crew.

  15. EPR investigation of some gamma-irradiated excipients

    NASA Astrophysics Data System (ADS)

    Aleksieva, Katerina; Yordanov, Nicola D.

    2012-09-01

    The results of electron paramagnetic resonance (EPR) studies on some excipients: lactose, microcrystalline cellulose (avicel), starch, dioxosilane (aerosil), talc and magnesium stearate before and after gamma-irradiation are reported. Before irradiation, all samples are EPR silent except talc. After gamma-irradiation, they show complex spectra except magnesium stearate, which is EPR silent. Studies show the influence of gamma-irradiation on EPR spectra and stability of gamma-induced radicals. Analysis of the EPR spectrum of gamma-irradiated talc shows that this material is radiation insensitive. Only lactose forms stable-free radicals upon gamma sterilization and can be used for identification of radiation processing for a long time period thereafter.

  16. THE SPECTRUM OF ISOTROPIC DIFFUSE GAMMA-RAY EMISSION BETWEEN 100 MeV AND 820 GeV

    SciTech Connect

    Ackermann, M.; Buehler, R.; Ajello, M.; Albert, A.; Blandford, R. D.; Bloom, E. D.; Bottacini, E.; Caliandro, G. A.; Atwood, W. B.; Baldini, L.; Bellazzini, R.; Ballet, J.; Bastieri, D.; Buson, S.; Bechtol, K.; Bissaldi, E.; Brandt, T. J.; Bregeon, J. [Laboratoire Univers et Particules de Montpellier, Université Montpellier 2, CNRS Bruel, P. E-mail: bechtol@kicp.uchicago.edu [Laboratoire Leprince-Ringuet, École Polytechnique, CNRS and others

    2015-01-20

    The γ-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse γ-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission (DGE), and a longer data accumulation of 50 months allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 ± 0.02 and a break energy of (279 ± 52) GeV using our baseline DGE model. The total intensity attributed to the IGRB is (7.2 ± 0.6) × 10{sup –6} cm{sup –2} s{sup –1} sr{sup –1} above 100 MeV, with an additional +15%/–30% systematic uncertainty due to the Galactic diffuse foregrounds.

  17. N-SAP and G-SAP neutron and gamma ray albedo model scatter shield analysis program

    NASA Technical Reports Server (NTRS)

    Sapovchak, B. J.; Stephenson, L. D.

    1967-01-01

    Computer program calculates neutron or gamma ray first order scattering from a plane or cylindrical surface to a detector point. The SAP Codes, G-SAP and N-SAP, constitute a multiple scatter albedo model shield analysis.

  18. Soft X-ray emission lines in the afterglow spectrum of GRB 011211: A detailed XMM-Newton analysis

    NASA Astrophysics Data System (ADS)

    Reeves, J. N.; Watson, D.; Osborne, J. P.; Pounds, K. A.; O'Brien, P. T.

    2003-05-01

    We report on an XMM-Newton observation of the X-ray afterglow of the Gamma Ray Burst GRB 011211, originally detected by Beppo-SAX on 11th December 2001. The early afterglow spectrum obtained by XMM-Newton, observed 11 hours after the initial burst, appeared to reveal decaying H-like Kalpha emission lines of Mg, Si, S, Ar and Ca, arising in enriched material with an outflow velocity of order 0.1c (Reeves et al. \\cite{Reeves2002}). This was attributed to matter ejected from a massive stellar progenitor occurring shortly before the burst itself. Here, we present a detailed re-analysis of the XMM-Newton EPIC observations of GRB 011211. In particular, we show that the detection of the soft X-ray line emission appears robust, regardless of detector background, calibration, spectral binning, or the spectral model that is assumed. We demonstrate that thermal emission, from an optically thin plasma, is the most plausible model that can account for the soft X-ray emission, which appears to be the case for at least two burst afterglow spectra observed by XMM-Newton. The X-ray spectrum of GRB 011211 appears to evolve with time after the first 10 ks of the XMM-Newton observation as the Si and S emission lines are only detected during the first 10 ks of observation. The observations suggest that thermal emission is present during the early afterglow spectrum, whilst a power-law component dominates the latter stages. Finally we estimate the mass of the ejected material in GRB 011211 to be of the order 4-20 solar masses.

  19. Normal mode and experimental analysis of TNT Raman spectrum

    NASA Astrophysics Data System (ADS)

    Liu, Yuemin; Perkins, Richard; Liu, Yucheng; Tzeng, Nianfeng

    2017-04-01

    In this study, a Raman spectrum of TNT was characterized through experiments and simulated using 22 hybrid density functional theory (DFT) methods. Among the different hybrid DFT methods, it was found that the most accurate simulation results of the Raman shift frequency were calculated by the O3LYP method. However, the deviations of the calculated Raman frequencies from the experimental value showed no dependency on the abilities of the DFT methods in recovering the correlation energy. The accuracies of the DFT methods in predicting the Raman bands are probably determined by the numerical grid and convergence criteria for optimizations of each DFT method. It was also decided that the prominent Raman shift 1362 cm-1 is mainly caused by symmetric stretching of the 4-nitro groups. Findings of this study can facilitate futuristic development of more effective surface enhanced Raman spectroscopy/scattering (SERS) substrates for explosive characterization and detection.

  20. Factor analysis of the Autism Spectrum Screening Questionnaire.

    PubMed

    Posserud, Britt; Lundervold, Astri J; Steijnen, Maaike C; Verhoeven, Sophie; Stormark, Kjell Morten; Gillberg, Christopher

    2008-01-01

    The present study investigated the factor structure of parent and teacher Autism Spectrum Screening Questionnaire (ASSQ) in a population of 7-9 years old children. For validation purposes, factors derived were correlated with results on the Strengths and Difficulties Questionnaire (SDQ). A three-factor solution was identified on both parent and teacher ASSQ. Most of the variance was explained by one factor including measures of social function, validated by a high correlation with the SDQ peer problems scale. The second factor included measures of autism-associated problems. The items allocated to the third factor were more specific for a cognitive style typically found in high-functioning individuals with autism/Asperger syndrome. This factor did not correlate highly with any of the SDQ subscales. The results indicated that the screening efficiency of ASSQ could be increased by closer examination of the individual profile of factor scores.